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WO2008007961A2 - Hoisting device with overload detection - Google Patents

Hoisting device with overload detection Download PDF

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Publication number
WO2008007961A2
WO2008007961A2 PCT/NL2007/050345 NL2007050345W WO2008007961A2 WO 2008007961 A2 WO2008007961 A2 WO 2008007961A2 NL 2007050345 W NL2007050345 W NL 2007050345W WO 2008007961 A2 WO2008007961 A2 WO 2008007961A2
Authority
WO
WIPO (PCT)
Prior art keywords
hoisting
hoist
indicator
force
hoisting device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/NL2007/050345
Other languages
French (fr)
Other versions
WO2008007961A3 (en
Inventor
Peter Paul Alexander Berk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
PARTNERS VOOR STRATEGIE EN MANAGEMENT ZWOLLE BV
Original Assignee
PARTNERS VOOR STRATEGIE EN MANAGEMENT ZWOLLE BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by PARTNERS VOOR STRATEGIE EN MANAGEMENT ZWOLLE BV filed Critical PARTNERS VOOR STRATEGIE EN MANAGEMENT ZWOLLE BV
Publication of WO2008007961A2 publication Critical patent/WO2008007961A2/en
Publication of WO2008007961A3 publication Critical patent/WO2008007961A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C1/00—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles
    • B66C1/10—Load-engaging elements or devices attached to lifting or lowering gear of cranes or adapted for connection therewith for transmitting lifting forces to articles or groups of articles by mechanical means
    • B66C1/22—Rigid members, e.g. L-shaped members, with parts engaging the under surface of the loads; Crane hooks
    • B66C1/34—Crane hooks
    • B66C1/40—Crane hooks formed or fitted with load measuring or indicating devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR
    • F16G13/00—Chains
    • F16G13/12—Hauling- or hoisting-chains so called ornamental chains
    • F16G13/14—Hauling- or hoisting-chains so called ornamental chains built up from readily-separable links
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/04—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring tension in flexible members, e.g. ropes, cables, wires, threads, belts or bands
    • G01L5/047—Specific indicating or recording arrangements, e.g. for remote indication, for indicating overload or underload

Definitions

  • This invention relates to a hoisting device comprising a hoist part with an indicator part, in particular for overload detection.
  • Hoist parts of this type may be, inter alia, a link of a chain, the end of a cable, the end of a hoisting belt, a coupling link, a hoisting hook or a hoisting eye.
  • GB- 1.366.108 discloses an overload indication for a chain which is based on the deformation of a round link.
  • this round link is provided with a plastic body which breaks when the round link deforms under stress. At that stage, the link already deforms to a considerable extend.
  • US-5.745.042 discloses an overload indicator based on an electrical circuit.
  • the indicator uses strain gauges or a coil-based device.
  • an isolation element is provided between two links which should keep these links electrically isolated from each other.
  • an additional measuring circuit is provided. This insulator is clearly not designed to break or deform permanently.
  • US-4.409.841 discloses a fatigue damage indicator which includes a thin plate mounted between or integral with two members to which a stress is to be applied, the disposition of the two members being such that the thin plate is stressed in shear. Slots extending in the direction of the applied stress may be provided to ensure that cracks formed by fatigue stress propagate in a desired direction and the crack propagation is designed to ensure that a part of the plate becomes detached or is bent substantially away.
  • US-4.578.941 discloses an overload detection and safety arrangement for a load carrying link chain, including a fuse link having link plates connected by a fuse bar of a tensile strength less than the tensile strength of the remainder of the load carrying chain, the fuse link being laced into the remainder of the chain.
  • the fuse bar is designed to break under predetermined overload conditions, but is positioned and arranged to carry normal tensile loads on the device.
  • a safety link offset from but substantially parallel to the line of tension through the fuse bar, connects the link plates.
  • the safety link has a tensile strength greater than the tensile strength of the fuse bar and at least substantially equal to the tensile strength of the remainder of the chain, the safety link holding the load when the fuse bar breaks due to overload conditions.
  • EP1232991 describes a hoisting device which has wear indicator parts. The parts are exposed to the effect of wear and the state of the indicator part gives an idea of the remaining life of the hoisting device.
  • DE4408562 describes cams provided in a hoisting element to prevent the load sliding on the hoisting element.
  • the present invention has the aim of solving some of the outlined problems and providing a simple, safe or controlled overload indication for a hoisting device.
  • the invention has the further aim of providing a feature which gives a warning of wrong usage, both to a user and to a supplier.
  • the invention provides a hoisting device comprising a first hoist part and a second hoist part which engage in one another for transmitting a hoisting force and is provided with an indicator part, wherein the indicator part is permanently deformable by a pressure force applied by the transmitted hoisting force onto it by the first and second hoisting part, is located between the first and second hoist parts when the hoisting force is being transmitted, is designed to permanently deform by a pressure force generated by a transmitted hoisting force which is greater than a minimum limit force, preferably a hoisting force greater than a working load limit for at least one of the hoist parts, and provides a visual indication of the application of a hoisting force above the minimum limit force.
  • deformation by pressure force it is possible to obtain an indicator which gives an indication of possible incorrect use without actual or permanent damage of the hoist part occurring.
  • This pressure force results from the hoisting force.
  • deformation by pressure proves to be easier to adjust and easier to control.
  • an indicator working on pressure force makes it possible to use the indicator at places on a hoist part other than the usual ones and a multiplicity of new designs proves possible. Furthermore, it can be accurate without disrupting the hoisting process.
  • the response of the indicator in an embodiment is designed to have a discrete deformation range. When an load situation above the predefined limit occurs, this indicator has a direct response and deform.
  • the overload is preferably detected independently of the visible deformation of the hoist part itself, because this is the very thing that needs to be prevented, and, for controllable detection of overload, use is made in this case of a pressure force, greater than the maximum hoisting force, which leads to plastic deformation of an indicator part instead of to fracture or deformation by tensile strain.
  • the overload indicator of the invention can in a very simple manner provide a visual indication of the use of a hoisting part beyond its indicated load limits. In fact, it is even possible to provide such an indication even before the hoisting part (or, for that matter any other part in the hoisting chain of elements) gets (elastically) deformed.
  • Maximum hoisting force is in this context understood as the maximum permitted hoisting load as prescribed in the specifications for a particular hoisting element. This is in fact also indicated as WLL which stands for "workload limit".
  • Set or design force is in this context understood as the hoisting force at which the indicator part is substantially plastically deformed, while at the same time the hoist part is substantially elastically deformed and there is consequently an indication to the user as to whether he is employing the hoist part in a safe manner during the operations.
  • the hoisting part can be a shackle, a threading eye, a link, a crane hook or hoisting eye.
  • the indicator part is permanently deformable by a pressure force generated by a transmitted hoisting force which is greater than a minimum limit force, preferably greater than the maximum prescribed hoisting force for the hoist part.
  • the hoisting device has a further, second hoist part which cooperates with the first hoist part, in particular the first and second hoist parts engage in one another, wherein the first hoist part and second hoist part transmit the hoisting force and the indicator part is located between the first and second hoist parts while the hoisting force is being transmitted.
  • the indicator part will be mounted between the first and second hoist parts. Because of this the hoisting force is transmitted from the first to the second hoist part by the indicator part.
  • the indicator part is designed to deform plastically by a pressure force generated by a transmitted hoisting force which is smaller than a maximum limit force, preferably by a pressure force generated by a transmitted hoisting force which is smaller than the hoisting force which substantially permanently deforms the first hoist part.
  • the indicator part is designed to deform plastically by means of a pressure force generated by a transmitted hoisting force which is smaller than the hoisting force which substantially elastically deforms the first hoist part.
  • the first and second hoist parts are looped or hitches parts
  • the indicator part comprises a cam on the first indicator part with at least part of its cam surface, in use, experiencing the pressure force from the second hoist part.
  • a cam provides a well-defined and high point concentrated load. This makes it possible to engineer the cam to allow it to deform plastically under a set load level. In particular, it may deform before the structural integrity of one of the parts is endangered. In fact, it can deform even before elastic deformation occurs of one of the parts.
  • the indicator part is an expendable part.
  • An advantage of this embodiment is that it is possible to design the indicator part to give an indication of the event of a load which is for instance below a load which elastically deforms the hoisting element, or below a load which starts plastic deformation of the hoisting part. In such an event, the hoisting element can still be used, and the indicator part can be replaced. This could for instance serve as a guarantee.
  • the indicator part is partially hardened.
  • the indicator part is surface-hardened at least at the point where the pressure force is exerted during use. In this way, when there is a pressure force the underlying softer material will be pressed in, while the indicator part still has great wear resistance.
  • the indicator part comprises a rim which extends from the first hoist part.
  • the indicator part comprises a bendable element, a crumple zone, a kinkable element or a combination thereof.
  • Each of these possibilities has its own advantages. All of these embodiment provide a visual indication of a load which is beyond a designed limit:
  • the indicator parts are designed to show deformation of to break above a design limit which me well be below the actual workload limit of the hoisting element. It may even be possible to used various possibilities together which all fail at a different design limit.
  • the indictor part is crushable by pressure force greater than a design force to be set or a designed load limit.
  • the indicator part is placed on the first hoist part as removably insertable.
  • the figures reproduce i.a. possible embodiments thereof. This may be a ring which has to be pressed into an eye or a (resilient) part which extends along a part of the inner circumference of an eye or link and clamps therein.
  • the indicator part is identifiable. In other words, an indication is applied therein or thereon, which is detectable or perceptible.
  • the indicator part comprises a hollow pipe.
  • the indicator part comprises a thin-walled open profile.
  • the indicator part is weakened by local removal of material.
  • the weakening is preferably at the point where the pressure force is exerted.
  • the indicator part consists of two or more parts.
  • the second hoist part is provided with a second indicator part and the first and second indicator parts exert the pressure force on one another when transmitting the hoisting force.
  • the second indicator part is designed not to deform when the first indicator part plastically deforms.
  • first and second indicator parts by cooperation of first and second indicator parts the surface pressure between them is intensified.
  • the second indicator part is hardened in its entirety.
  • the second indicator part comprises a rim or border which extends from the second hoist part.
  • the first indicator part comprises a rim which extends from the second hoist part and the second indicator part comprises a rim which extends from the second hoist part, wherein during the hoisting force the rims are crossed over one another. This reduces the contact surface, increasing the local pressure force such, that almost a point load occurs. Because of this the first indicator part will quickly and visibly collapse in the event of overloading.
  • the second indicator part comprises a spring, the bias of which is adjustable.
  • the hoisting device comprises a converter which provides a further easily perceptible indication.
  • the converter comprises a light source or a sound source, or else a further source for emitting a sensually perceptible signal.
  • a circuit On collapse, a circuit can be closed and a light or sound signal emitted. A coloured part, for example, may also become visible as a warning.
  • the converter can be switched on and off, for example by the deformation in or of the indicator part.
  • the first hoist part has been chosen from the group consisting of the end of a chain, the end of a cable, the end of a hoisting belt, a coupling link, a hoisting hook and a hoisting eye.
  • the hoisting force puts the first indicator part under shear load, whereby said indicator part deforms or breaks.
  • the first or second indicator part is provided with a mark, preferably a unique mark such as a serial code.
  • the first and/or second hoist part is provided with a mark, preferably a unique mark, such as a serial code, wherein the indicator part mark and the hoist part mark have a mutual connection.
  • a mark preferably a unique mark, such as a serial code
  • the indicator part mark and the hoist part mark have a mutual connection.
  • the invention furthermore relates to a hoisting device comprising first and second hoist parts which transmit a hoisting force, wherein the hoist parts are mutually connected by means of at least one breaking element which, put under tensile strain by the pressure force, deforms or breaks, and the hoist parts are mutually connected by means of a connecting part which remains intact on deformation or breaking of the breaking element.
  • the load-bearing function of the hoist parts therefore remains intact while visually incorrect use or overloading can be made visible.
  • the invention furthermore relates to a hoisting device comprising a hoist part for transmitting a hoisting force and provided with an indicator part, wherein the indicator part shatters at least at the point of the pressure force because of a pressure force applied by the transmitted hoisting force.
  • the invention furthermore relates to a hoist part, known to be suitable and intended as a hoist part for a hoisting device as described or shown in this description.
  • the invention furthermore relates to an indicator part, known to be suitable and intended as indicator part for a hoisting device as described or shown in this description.
  • the overload indicator which has a replaceable part, such as the ring for instance, may become part of an inspection routine.
  • a part of the periodic inspection will be the replacement of the replaceable part or parts of the overload indicator.
  • the replaced part will be inspected to see if the warranty can be extended for another period.
  • the parts, to that end, may have the authentication mark described above.
  • the overload indicator provides evidence of the use within or without certified limits. This will give certainty to both the manufacturer and the user.
  • Figures Ia- Id show several views of a first embodiment of a hoisting device according to the invention
  • Figures 2a-2c show several views of a second embodiment of the hoisting device
  • Figures 3a-3c show several views of a third embodiment of the hoisting device
  • Figures 4a-4d show several views of a fourth embodiment of the hoisting device
  • Figures 5a-5c show a variant of the embodiment of Figures 4a-4a;
  • Figures 6a-6c likewise show a variant of the embodiment of Figures 4a-4d;
  • Figures 7a-7d show several views of a fifth embodiment of the hoisting device
  • Figures 8a-8c show a combination of the embodiments in Figures 5a-5c and 6a-6c.
  • Figures 9a- 9b show an embodiment of an alternative overload indicator.
  • Figures 10a- 10b show the overload indicator from Figures 9a- 9b doubly embodied in a hoisting eye.
  • Figures 1 Ia-I Ic show a variant of the overload indicator from Figures. 10a- 10b.
  • Figures 12a- 12b show the overload indicator from Figures 1 Ia-I Ic in a single embodiment.
  • Figures 13a-13b show views of a sixth embodiment of the hoisting device
  • Figures 14a-14e show several views of a seventh embodiment of the hoisting device
  • Figures 15a-15d show an indicator part as a ceramic rim or ring
  • Figures 16a-16d show an indicator part provided with a crumple zone
  • Figures 17a- 17c show an indicator part provided with a kinkable element
  • Figures 18a-18d an indicator part provided with bendable lips
  • Figures 19a- 19b show a further embodiment of an overload indicator.
  • Figure Ia shows a hoist part 1 provided with a first indicator part 2, circumferentially extending as a narrow raised rim along the inner circumference of hoist part 1.
  • the first indicator part 2 is further embodied as a closed ring 6 with supports 7 at regular intervals, as shown in Figure Ic, in which an enlarged reproduction of part of Figure Ia is reproduced.
  • the indicator part 2 of hoist part 1 cooperates with indicator part 3.
  • Indicator part 3 is provided on a hoist part 4 and is here embodied as a narrow raised rim extending along the inner circumference of hoist part 4. This means that the hoisting force applied to hoist part 1 is transmitted via the indicator parts 2 and 3 to hoist part 4.
  • a hoisting force applied to hoist part 1 is greater than or equal to a set value, in other words a design value on which both parts are mutually designed, the surface pressure between indicator parts 2 and 3 ensures plastic deformation of indicator part 2.
  • a set value in other words a design value on which both parts are mutually designed
  • the surface pressure between indicator parts 2 and 3 ensures plastic deformation of indicator part 2.
  • Said part can be placed in hoist part 1 as a separately insertable part which is clamped into hoist part 1 by means of pressing, for example.
  • the indicator part 2 has a circumferential ring 6 of material which preferably does not wear under the influence of the circumferential cam or rim 3 of hoist part 4.
  • deformation parts 7 are provided on the ring 6.
  • deformation parts 7 are designed such that if the force transmitted to these deformation parts via ring 6 is greater than a set value, the material of deformation part 7 will plastically deform. In the case of visual detection this deformation will be immediately visible.
  • a deformation part 7 may be a further ring between ring 6 and hoist part 1.
  • the deformation parts 7 are a series of separate parts with a gap, as reproduced in the side view of Figure Ic.
  • Figure 2a shows a hoist part 11 provided with a first indicator part 12 which circumferentially extends as a U-profile along part of the inner circumference of hoist part 11 and wherein the shape of the profile matches hoist part 11, with the exception of upper edge 16 which lies clear with a gap 17.
  • Upper edge 16 of indicator part 12 cooperates with indicator part 13 which is provided on a hoist part 14 and extends along the inner circumference of hoist part 14.
  • the hoisting force applied to hoist part 11 is transmitted via the indicator parts 12, 13 to hoist part 14. If a hoisting force is greater than or equal to a set value, the hoisting force between indicator parts 12, 13 ensures a plastic deformation of upper edge 16 of indicator part 12.
  • Figure 2b shows the embodiment of Figure 2b in section along line Hb-IIb.
  • Figure 2c shows a detail of the part indicated in Figure 2b.
  • indicator part 12 and indicator part 13 are chosen such that they do not, or hardly, wear down on one another during use.
  • indicator part 12 fits against the inner surface of hoist part 11, by, for example, bringing both legs of indicator part 12 towards one another, making it relatively easy to fit or replace.
  • Figure 3 a shows an embodiment which is similar to that of Figure 2a, wherein, once a set design value has been exceeded, i.e. after detection, the first indicator part 22 likewise deforms in the direction of hoist part 21.
  • Indicator part 22 is reproduced in detail in Figure 3c.
  • First indicator part 22 partially circumferentially extends as a U-profile along the inner circumference of hoist part 21.
  • the profile 22 is joined to hoist part 21 by the rims 27, 28, wherein indicator part 22 cooperates with indicator part 23 which is provided on a hoist part 24 and extends along the inner circumference of hoist part 24.
  • the hoisting force applied to hoist part 21 is in this case transmitted via the indicator parts 22, 23 to hoist part 24.
  • Indicator part 22 is furthermore provided with a weakening 26 by local removal of material at the top of the U-profile, where the force is chiefly transmitted. If a hoisting force is greater than or equal to the set design force, the hoisting force between indicator parts 22, 23 ensures deformation chiefly at the point of the weakening 26.
  • Figures 4a-4d show an embodiment of the present invention comprising a hoist part 31 provided with a relatively soft first indicator part 32, which circumferentially extends as a narrow raised rim along the inner circumference of hoist part 31.
  • Indicator part 32 is again embodied as a closed ring.
  • Indicator part 32 here cooperates with hardened second indicator part 33, which is provided on a hoist part 34 and is embodied as a narrow raised rim or circumferential cam 33 extending along the inner circumference of hoist part 34.
  • the hoisting force applied to hoist part 31 is in this case transmitted via the indicator parts 32, 33 to hoist part 34.
  • indicator part 32 here a ring 32 placeable in hoist part 31, is provided on the side facing away from hoist part 31 with a circumferential cam or rim. In the event of overload the cam will plastically deform at the point where it abuts against (hardened) cam 33 of hoist part 34.
  • the indicator parts 32, 33 are hardened such that wear is avoided.
  • indicator part 33 is fully hardened, while indicator part 32 is hardened chiefly on the surface and is otherwise relatively soft.
  • the indicator part is made of steel with a yield point of approximately 210 MPa.
  • the hardened layer has attained a yield point of approximately 1800 MPa.
  • the cam 33 is made of hardened steel with a yield point of approximately 400 MPa. These figures are indicative.
  • the indicator parts for most embodiments will often be made of carbon steel.
  • a surface hardening such as laser hardening, induction hardening or nitriding will be applied to the indicator part.
  • the second indicator part is usually hardened through at the point where the pressure force is exerted on the first indicator part, the contact surface, in a manner known by the person skilled in the art.
  • both indicator parts 32, 33 comprise rims which are pressed onto one another when a load is applied, and the rims are at an angle with respect to one another, a high point concentrated load will exist between both rims. Thus, it is be possible to cause a plastic deformation in one of the rims before causing structural weakening of the hoist parts.
  • Figure 5a shows the embodiment of Figure 4a with the difference that now the first indicator part 32 is embodied identically to part 33 as an integral part of hoist parts 31 and 34 respectively.
  • the indicator parts can be produced using techniques such as forging and milling, following which (partial) hardening subsequently takes place. Again, as in the embodiment of figs 4, a high point concentrated load will develop.
  • Figure 6a shows the embodiment of Figure 5a with the difference that now the second indicator part 33 is embodied as a hardened part of hoist part 34 and not formed by a protruding part.
  • FIGS 7a-7d show the embodiment of Figure Id with the difference that now the first indicator part 2 on hoist part 1 is embodied as a part which is weakened by local removal of material.
  • Indicator part 2 here comprises a ring 2 with an inner surface 8 which forms a surface which is adjacent to cam or rim 3 of hoist part 4.
  • Indicator part 2 furthermore has an outer surface 9 which is adjacent to hoist part 1.
  • Ring 2 is provided with removed parts 10, consecutive in an axial direction. If there is a load greater than the set design value, i.e. the working load limit (WLL), in general twice the nominal load (WLL) (i.e.
  • WLL working load limit
  • FIGS 8a-8c show the embodiment of Figure 4a-d with the difference that now both the first indicator part 32 is embodied as an integral soft part of hoist part 31 and the second indicator part 33 is embodied as a hardened part of hoist part 34 and is not formed by a protruding part or rim. In most cases, the surface will be hardened, as indicated above.
  • Figures 9a- 9b show an embodiment of an alternative overload indicator.
  • a first indicator part 90 comprising a breaking element 91, is fastened to a first hoisting eye 92 and a second hoisting eye 93.
  • Breaking element 91 comprises a cover (or sleeve or casing) 91 with two cover halves 94, 95. These parts can for instance be screwed together.
  • Eyes 92, 93 have extensions 98, 99 which extend into the cover 91.
  • the extensions 98, 99 are mutually connected in cover 91 by means of a fracture element 97. Fracture element 97 can be accommodated in cover 91, placed as freely movable along its longitudinal axis.
  • Fracture element 97 comprises a first fracture part 100, a second fracture part 101 and a breaking part 102.
  • fracture element 97 cannot slide inside cover 91.
  • breaking part 102 will first constrict and then break in accordance with its design. Fracture part 101 will then be pulled up by eye 93 until it is retained by the top of cover 91.
  • the inside of cover halve 95 may be tapered or it may have a cam or groove corresponding with a groove or cam of the fracture part 101. Retaining will provide a permanent indication. This means that coloured part 96 of the extension 99 will now stick out of the cover 91 so that overload is immediately visible.
  • both cover parts 94, 95 are to be screwed together.
  • a disadvantage in comparison to the previous embodiments based on pressure is that in most cases the overload indicator based on tensile strain will snap or at least elongate. This, when snapping, it will put an extra load on the indicator.
  • Figures 10a- 10b show an alternative embodiment of the alternative indication as shown in Figures 9a-9b with the difference that this embodiment has two breaking elements 90 in a hoisting eye as reproduced in Figures 9a- 9b. Both legs 103, 104 of a hoisting eye 105 are here provided with a breaking element.
  • Figures 1 Ia-I Ic show a further alternative indicator of the kind also reproduced in Figures 10a- 10b and 9a- 9b, based on tensile strain.
  • Figure 1 Ib is a section XIb-XIb of Figure 11a
  • Figure 1 Ic is a section XIc-XIc of Figure 11a.
  • the fracture elements 119 are embodied as rings 119, locally weakened by the removal of material, whereby lips 123 remain which are loaded under shear load.
  • one set of cover parts 111, 112 is integrally formed at one end of each leg of eye 110.
  • the other ends 113 are provided with a ring 119.
  • the ring is mounted as removable/replaceable by means of a nut 120, for example.
  • One end 113 extends in axial direction in a cover part 118.
  • the fracture element 119 is in this case a ring 119 provided with an inner ring 121 and an outer ring 122, mutually concentrically connected by means of breaking parts 123. If the breaking parts fracture, the diameter of the fracture element will decrease, whereby the ends 113 can move axially in the cover (or sleeve part) 118 and a (possibly clamped) part of end 113 which was originally inside the cover 118 becomes visible.
  • the two cover parts 111 and 118 can mutually form an accommodation space between them, in which the edge of the ring 119 is to be accommodated, so that axial movement of end 113 is prevented until fracture parts 123 break.
  • Figures 12a- 12c show an embodiment of the present invention as in Figures 1 Ia-I Ic with the difference that in this case it relates to a single embodiment instead of a double one.
  • Figures 13 a- 13b show a hoisting eye 41 provided with a first indicator part 42 as a U in a part of the inner circumference of hoist part 41 and wherein the shape of the profile fits against hoist part 41 with the exception of upper edge 46 which lies clear from the surface of hoisting eye 41 and wherein upper edge 46 of indicator part 42 cooperates with indicator part 43 which is provided on a hoist part 44 and wherein the hoisting force applied to hoisting eye 41 is transmitted to hoist part 44 via the indicator parts 42, 43.
  • At least a part of the inner surface of hoisting eye 41 can be hardened. If a hoisting force applied to hoisting eye 41 is greater than or equal to a set value, the hoisting force between indicator parts 42, 43 ensures fracture of upper edge 46 of indicator part 42. Indicator part 42 can have a weakening 49 to ensure deformation at the right place.
  • FIGs 14a-14e show a hoisting device an overload indicator based on pressure force causing deformation.
  • Hoist part 51 comprises a borehole 58 with a seating with, placed thereon, a first indicator part 52 which in this embodiment is embodied like fracture element 119 from Figures 11 and 12.
  • Indicator part 52 cooperates with pin 53 in engagement with hoisting eye 54.
  • a U-profile which at least partially circumferentially extends along the inner circumference of hoist part 51 and cooperates therewith to hold pin 53 in the outlined position with borehole 58.
  • pin 53 will exert a pushing force on indicator part 52 of such a dimension that the fracture parts 60 break and the pin 53 can penetrate into hole 58. This is easily perceptible visually.
  • This embodiment is based on pressure force, and provides an easily replaceable deforming element. In this embodiment, the element fractures.
  • Figures 15a-15d show the embodiment of Figure Ia with the difference that now the first indicator part 2 is embodied on hoist part 1 as a ceramic rim or cam 2 which circumferentially extends along the inner circumference of hoist part 1.
  • indicator part 2 will pulverise at the point of engagement with indicator part 3. This makes wrong usage or loading above the maximum hoisting force easy to perceive.
  • Figures 16a-16d shows the embodiment of Figure Ia with the difference that now the first indicator part 2 is embodied on hoist part 1 as a cam or rim 2 which circumferentially extends along the inner circumference of hoist part 1 and wherein indicator part 2 comprises a crumple zone as made clear in Figure 16d.
  • the rim 2 which is at an angle with respect to the indicator part 2 provides a relative small contact service, providing a high point concentrated load which is clearly defined.
  • Figures 17a- 17c shows the embodiment of Figure Ia with the difference that now the first indicator part 2 on hoist part 1 is a kinkable or snapable element 2, embodied as a cam or rim which circumferentially extends along the inner circumference of hoist part 1 and wherein kinkable element 2 is here weakened by a notch 5.
  • a load greater than the set design value the kinkable element 2 will buckle outwards. This kinking or bending can also be promoted or stimulated by a small bend in stead of notch 5.
  • Figures 18a-18d shows the embodiment of Figure Ia with the difference that now the first indicator part 2 on hoist part 1 is embodied as a bendable part 2 with a bendable lip or bendable lips 180 as shown in Figure 18d.
  • Bendable part 2 circumferentially extends on the inner circumference of hoist part 1. In the event of load greater than the set design value the bendable lip or bendable lips 180 will bend outwards.
  • Figures 19a- 19b show an embodiment of the invention in which the hoist part 1 has an indicator part 2 which extends over part of the inner circumference of hoist part 1.
  • the indicator part 2 is insertable in the interior of link 1, but in this embodiment, the indicator part 2 is clamped between blocking parts 190.
  • the indicator part 3 has two sharp cutting edges 191. In order to prevent damage of the cutting edges during use, it has a small radius between the cutting edges, at the contact surface 193.
  • this contact surface will exert a pressure force on the lips 193 of indicator part 2.
  • the lips 192 will start to bend when a hoisting force is exerted.
  • the cutting edges will come in contact with the surface of the lips 192.
  • these cutting edges 191 will cut through the surface of the lips 192 and the indicator part 2 will deform very rapidly.
  • a cutting edge will come in contact after a first deformation, it will then cut through a surface layer of material, and the indicator will deform completely.
  • the first deformation may be an elastic deformation.
  • an advantage of this particular embodiment is that the indicator part will have a very sharp response. As soon as a load above a designed indication level occurs, the indicator will give a visual indication.
  • the cutting edges are first protected by a contact surface and will only get in contact with the indicator surface when a load passes a set level.
  • the design of the indicator part is such that this only occurs at a set level.
  • the surface properties, especially local hardening, is such that the cutting edges cut through the surface above this set level.
  • the lips are engineered in such a way that after cutting though the surface layer, they will bend completely, giving a visual indication of overload above the set level.

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  • General Engineering & Computer Science (AREA)
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Abstract

The invention pertains to a hoisting device comprising a first hoist part and a second hoist part which engage in one another for transmitting a hoisting force and which is provided with an indicator part, wherein the indicator part is permanently deformable by a pressure force applied by the transmitted hoisting force onto it by the first and second hoisting part, is located between the first and second hoist parts when the hoisting force is being transmitted, is designed to permanently deform by a pressure force generated by a transmitted hoisting force which is greater than a minimum limit force, preferably a hoisting force greater than a working load limit for at least one of the hoist parts, and provides a visual indication of the application of a hoisting force above the minimum limit force.

Description

Hoisting device with overload detection
Background of the invention
This invention relates to a hoisting device comprising a hoist part with an indicator part, in particular for overload detection.
Hoist parts of this type may be, inter alia, a link of a chain, the end of a cable, the end of a hoisting belt, a coupling link, a hoisting hook or a hoisting eye.
Known from the state of the art is, inter alia, overload detection using markings on the hoisting element; from patent US5452679, for example, where use is made of markings on both sides of the hook, whereby deformations of the hook are easily perceptible visually. The disadvantage of this method is that overload detection takes place only where there is visible, possibly already irreversible deformation of the hook, whereby the hook is no longer usable.
Further known from the state of the art is overload detection on the basis of tensile force. US4578941, for instance, shows a hoisting chain with a detection rod placed parallel to a link of the chain. If a certain tensile strain is exceeded, the detection rod will break. The disadvantage of this method is that the breaking of the detection rod is a relatively uncontrolled process and that it is in this case possible for permanent deformation of the chain to occur due to impact load.
GB- 1.366.108 discloses an overload indication for a chain which is based on the deformation of a round link. In an embodiment shown in fig. 9, this round link is provided with a plastic body which breaks when the round link deforms under stress. At that stage, the link already deforms to a considerable extend.
US-5.745.042 discloses an overload indicator based on an electrical circuit. The indicator uses strain gauges or a coil-based device. In order to prevent electrical overload of the circuit or the strain gauges in case of contacting a power line or lightning, an isolation element is provided between two links which should keep these links electrically isolated from each other. To check the electrical condition of the insulator an additional measuring circuit is provided. This insulator is clearly not designed to break or deform permanently.
US-4.409.841 discloses a fatigue damage indicator which includes a thin plate mounted between or integral with two members to which a stress is to be applied, the disposition of the two members being such that the thin plate is stressed in shear. Slots extending in the direction of the applied stress may be provided to ensure that cracks formed by fatigue stress propagate in a desired direction and the crack propagation is designed to ensure that a part of the plate becomes detached or is bent substantially away.
US-4.578.941 discloses an overload detection and safety arrangement for a load carrying link chain, including a fuse link having link plates connected by a fuse bar of a tensile strength less than the tensile strength of the remainder of the load carrying chain, the fuse link being laced into the remainder of the chain. The fuse bar is designed to break under predetermined overload conditions, but is positioned and arranged to carry normal tensile loads on the device. A safety link, offset from but substantially parallel to the line of tension through the fuse bar, connects the link plates. The safety link has a tensile strength greater than the tensile strength of the fuse bar and at least substantially equal to the tensile strength of the remainder of the chain, the safety link holding the load when the fuse bar breaks due to overload conditions.
Also known from the state of the art are hoisting devices provided with wear indicators. EP1232991 describes a hoisting device which has wear indicator parts. The parts are exposed to the effect of wear and the state of the indicator part gives an idea of the remaining life of the hoisting device. Finally, DE4408562 describes cams provided in a hoisting element to prevent the load sliding on the hoisting element.
Summary of the invention
The present invention has the aim of solving some of the outlined problems and providing a simple, safe or controlled overload indication for a hoisting device.
The invention has the further aim of providing a feature which gives a warning of wrong usage, both to a user and to a supplier.
To this end, the invention provides a hoisting device comprising a first hoist part and a second hoist part which engage in one another for transmitting a hoisting force and is provided with an indicator part, wherein the indicator part is permanently deformable by a pressure force applied by the transmitted hoisting force onto it by the first and second hoisting part, is located between the first and second hoist parts when the hoisting force is being transmitted, is designed to permanently deform by a pressure force generated by a transmitted hoisting force which is greater than a minimum limit force, preferably a hoisting force greater than a working load limit for at least one of the hoist parts, and provides a visual indication of the application of a hoisting force above the minimum limit force. Using deformation by pressure force it is possible to obtain an indicator which gives an indication of possible incorrect use without actual or permanent damage of the hoist part occurring. This pressure force results from the hoisting force. Moreover, deformation by pressure proves to be easier to adjust and easier to control. Furthermore, an indicator working on pressure force makes it possible to use the indicator at places on a hoist part other than the usual ones and a multiplicity of new designs proves possible. Furthermore, it can be accurate without disrupting the hoisting process.
In order to provide a clear indication of an overload situation or a load above a certain predefined limit, which may be any preset limit, the response of the indicator in an embodiment is designed to have a discrete deformation range. When an load situation above the predefined limit occurs, this indicator has a direct response and deform.
The overload is preferably detected independently of the visible deformation of the hoist part itself, because this is the very thing that needs to be prevented, and, for controllable detection of overload, use is made in this case of a pressure force, greater than the maximum hoisting force, which leads to plastic deformation of an indicator part instead of to fracture or deformation by tensile strain. The overload indicator of the invention, can in a very simple manner provide a visual indication of the use of a hoisting part beyond its indicated load limits. In fact, it is even possible to provide such an indication even before the hoisting part (or, for that matter any other part in the hoisting chain of elements) gets (elastically) deformed. Maximum hoisting force is in this context understood as the maximum permitted hoisting load as prescribed in the specifications for a particular hoisting element. This is in fact also indicated as WLL which stands for "workload limit".
Set or design force is in this context understood as the hoisting force at which the indicator part is substantially plastically deformed, while at the same time the hoist part is substantially elastically deformed and there is consequently an indication to the user as to whether he is employing the hoist part in a safe manner during the operations.
The above-mentioned safety requirements are described, inter alia, in EN 13155:2003(E), for example, in paragraph 5.1.1 thereof. This specific standard applies to so-called vice clamps, but is similar for other hoist parts, such as hooks, hoisting eyes and the like. The maximum static load or loading to be withstood will mostly be a maximum of 2-3 times the working load limit.
In this invention, as already mentioned above, the hoisting part can be a shackle, a threading eye, a link, a crane hook or hoisting eye.
In one embodiment the indicator part is permanently deformable by a pressure force generated by a transmitted hoisting force which is greater than a minimum limit force, preferably greater than the maximum prescribed hoisting force for the hoist part. In one embodiment the hoisting device has a further, second hoist part which cooperates with the first hoist part, in particular the first and second hoist parts engage in one another, wherein the first hoist part and second hoist part transmit the hoisting force and the indicator part is located between the first and second hoist parts while the hoisting force is being transmitted. In one embodiment the indicator part will be mounted between the first and second hoist parts. Because of this the hoisting force is transmitted from the first to the second hoist part by the indicator part.
In one embodiment the indicator part is designed to deform plastically by a pressure force generated by a transmitted hoisting force which is smaller than a maximum limit force, preferably by a pressure force generated by a transmitted hoisting force which is smaller than the hoisting force which substantially permanently deforms the first hoist part. In one embodiment the indicator part is designed to deform plastically by means of a pressure force generated by a transmitted hoisting force which is smaller than the hoisting force which substantially elastically deforms the first hoist part.
In an embodiment, the first and second hoist parts are looped or hitches parts, and the indicator part comprises a cam on the first indicator part with at least part of its cam surface, in use, experiencing the pressure force from the second hoist part. Using a cam provides a well-defined and high point concentrated load. This makes it possible to engineer the cam to allow it to deform plastically under a set load level. In particular, it may deform before the structural integrity of one of the parts is endangered. In fact, it can deform even before elastic deformation occurs of one of the parts. In one embodiment the indicator part is an expendable part. An advantage of this embodiment is that it is possible to design the indicator part to give an indication of the event of a load which is for instance below a load which elastically deforms the hoisting element, or below a load which starts plastic deformation of the hoisting part. In such an event, the hoisting element can still be used, and the indicator part can be replaced. This could for instance serve as a guarantee.
In one embodiment the indicator part is partially hardened.
In one embodiment the indicator part is surface-hardened at least at the point where the pressure force is exerted during use. In this way, when there is a pressure force the underlying softer material will be pressed in, while the indicator part still has great wear resistance.
In one embodiment the indicator part comprises a rim which extends from the first hoist part. In one embodiment the indicator part comprises a bendable element, a crumple zone, a kinkable element or a combination thereof. Each of these possibilities has its own advantages. All of these embodiment provide a visual indication of a load which is beyond a designed limit: The indicator parts are designed to show deformation of to break above a design limit which me well be below the actual workload limit of the hoisting element. It may even be possible to used various possibilities together which all fail at a different design limit.
In one embodiment the indictor part is crushable by pressure force greater than a design force to be set or a designed load limit.
In one embodiment the indicator part is placed on the first hoist part as removably insertable. The figures reproduce i.a. possible embodiments thereof. This may be a ring which has to be pressed into an eye or a (resilient) part which extends along a part of the inner circumference of an eye or link and clamps therein.
In one embodiment the indicator part is identifiable. In other words, an indication is applied therein or thereon, which is detectable or perceptible. In one embodiment the indicator part comprises a hollow pipe.
In one embodiment the indicator part comprises a thin-walled open profile.
In one embodiment the indicator part is weakened by local removal of material. The weakening is preferably at the point where the pressure force is exerted.
In one embodiment, once the set pressure force has been exceeded the indicator part consists of two or more parts.
In one embodiment the second hoist part is provided with a second indicator part and the first and second indicator parts exert the pressure force on one another when transmitting the hoisting force. In one embodiment the second indicator part is designed not to deform when the first indicator part plastically deforms.
In one embodiment by cooperation of first and second indicator parts the surface pressure between them is intensified. In one embodiment the second indicator part is hardened in its entirety.
In one embodiment the second indicator part comprises a rim or border which extends from the second hoist part.
In one embodiment the first indicator part comprises a rim which extends from the second hoist part and the second indicator part comprises a rim which extends from the second hoist part, wherein during the hoisting force the rims are crossed over one another. This reduces the contact surface, increasing the local pressure force such, that almost a point load occurs. Because of this the first indicator part will quickly and visibly collapse in the event of overloading.
In one embodiment the second indicator part comprises a spring, the bias of which is adjustable.
In one embodiment the hoisting device comprises a converter which provides a further easily perceptible indication.
In one embodiment the converter comprises a light source or a sound source, or else a further source for emitting a sensually perceptible signal. On collapse, a circuit can be closed and a light or sound signal emitted. A coloured part, for example, may also become visible as a warning.
In one embodiment the converter can be switched on and off, for example by the deformation in or of the indicator part.
In one embodiment the first hoist part has been chosen from the group consisting of the end of a chain, the end of a cable, the end of a hoisting belt, a coupling link, a hoisting hook and a hoisting eye.
In one embodiment the hoisting force puts the first indicator part under shear load, whereby said indicator part deforms or breaks.
In one embodiment the first or second indicator part is provided with a mark, preferably a unique mark such as a serial code.
In one embodiment the first and/or second hoist part is provided with a mark, preferably a unique mark, such as a serial code, wherein the indicator part mark and the hoist part mark have a mutual connection. This can make it clear whether an indicator part and a hoist part belong together. This gives a supplier, for example, an indication of whether the indicator part is authentic.
The invention furthermore relates to a hoisting device comprising first and second hoist parts which transmit a hoisting force, wherein the hoist parts are mutually connected by means of at least one breaking element which, put under tensile strain by the pressure force, deforms or breaks, and the hoist parts are mutually connected by means of a connecting part which remains intact on deformation or breaking of the breaking element. The load-bearing function of the hoist parts therefore remains intact while visually incorrect use or overloading can be made visible. The invention furthermore relates to a hoisting device comprising a hoist part for transmitting a hoisting force and provided with an indicator part, wherein the indicator part shatters at least at the point of the pressure force because of a pressure force applied by the transmitted hoisting force.
The invention furthermore relates to a hoist part, known to be suitable and intended as a hoist part for a hoisting device as described or shown in this description.
The invention furthermore relates to an indicator part, known to be suitable and intended as indicator part for a hoisting device as described or shown in this description.
The overload indicator which has a replaceable part, such as the ring for instance, may become part of an inspection routine. A part of the periodic inspection will be the replacement of the replaceable part or parts of the overload indicator. In such a procedure, the replaced part will be inspected to see if the warranty can be extended for another period. The parts, to that end, may have the authentication mark described above.
Furthermore, in case of failure or damage, the overload indicator provides evidence of the use within or without certified limits. This will give certainty to both the manufacturer and the user.
Further aspects of the invention are described in the dependent claims and in the description of the figures below. The various aspects described therein can each be part of divisional patent applications from this patent application and can be mutually combined.
Brief description of the drawings
The invention will now be explained in more detail with reference to the appended figures in which: Figures Ia- Id show several views of a first embodiment of a hoisting device according to the invention;
Figures 2a-2c show several views of a second embodiment of the hoisting device;
Figures 3a-3c show several views of a third embodiment of the hoisting device; Figures 4a-4d show several views of a fourth embodiment of the hoisting device;
Figures 5a-5c show a variant of the embodiment of Figures 4a-4a;
Figures 6a-6c likewise show a variant of the embodiment of Figures 4a-4d;
Figures 7a-7d show several views of a fifth embodiment of the hoisting device;
Figures 8a-8c show a combination of the embodiments in Figures 5a-5c and 6a-6c. Figures 9a- 9b show an embodiment of an alternative overload indicator.
Figures 10a- 10b show the overload indicator from Figures 9a- 9b doubly embodied in a hoisting eye.
Figures 1 Ia-I Ic show a variant of the overload indicator from Figures. 10a- 10b.
Figures 12a- 12b show the overload indicator from Figures 1 Ia-I Ic in a single embodiment.
Figures 13a-13b show views of a sixth embodiment of the hoisting device;
Figures 14a-14e show several views of a seventh embodiment of the hoisting device;
Figures 15a-15d show an indicator part as a ceramic rim or ring;
Figures 16a-16d show an indicator part provided with a crumple zone; Figures 17a- 17c show an indicator part provided with a kinkable element;
Figures 18a-18d an indicator part provided with bendable lips;
Figures 19a- 19b show a further embodiment of an overload indicator.
Detailed description of embodiments
Figure Ia shows a hoist part 1 provided with a first indicator part 2, circumferentially extending as a narrow raised rim along the inner circumference of hoist part 1. The first indicator part 2 is further embodied as a closed ring 6 with supports 7 at regular intervals, as shown in Figure Ic, in which an enlarged reproduction of part of Figure Ia is reproduced. The indicator part 2 of hoist part 1 cooperates with indicator part 3. Indicator part 3 is provided on a hoist part 4 and is here embodied as a narrow raised rim extending along the inner circumference of hoist part 4. This means that the hoisting force applied to hoist part 1 is transmitted via the indicator parts 2 and 3 to hoist part 4. If a hoisting force applied to hoist part 1 is greater than or equal to a set value, in other words a design value on which both parts are mutually designed, the surface pressure between indicator parts 2 and 3 ensures plastic deformation of indicator part 2. In Figures Ic-Id indicator part 2 is reproduced in detail. Said part can be placed in hoist part 1 as a separately insertable part which is clamped into hoist part 1 by means of pressing, for example. The indicator part 2 has a circumferential ring 6 of material which preferably does not wear under the influence of the circumferential cam or rim 3 of hoist part 4. In this embodiment, deformation parts 7 are provided on the ring 6. These deformation parts 7 are designed such that if the force transmitted to these deformation parts via ring 6 is greater than a set value, the material of deformation part 7 will plastically deform. In the case of visual detection this deformation will be immediately visible. In one embodiment a deformation part 7 may be a further ring between ring 6 and hoist part 1. Preferably, above all to make visual inspection simple, the deformation parts 7 are a series of separate parts with a gap, as reproduced in the side view of Figure Ic. Figure 2a shows a hoist part 11 provided with a first indicator part 12 which circumferentially extends as a U-profile along part of the inner circumference of hoist part 11 and wherein the shape of the profile matches hoist part 11, with the exception of upper edge 16 which lies clear with a gap 17. Upper edge 16 of indicator part 12 cooperates with indicator part 13 which is provided on a hoist part 14 and extends along the inner circumference of hoist part 14. The hoisting force applied to hoist part 11 is transmitted via the indicator parts 12, 13 to hoist part 14. If a hoisting force is greater than or equal to a set value, the hoisting force between indicator parts 12, 13 ensures a plastic deformation of upper edge 16 of indicator part 12. This plastic deformation will lead to the gap 17 being pressed shut and indicator part 12 coming to lie fully against the inner surface of hoist part 11. This will make wrong usage or loading above the maximum hoisting force visually easy to perceive. Figure 2b shows the embodiment of Figure 2b in section along line Hb-IIb. Figure 2c shows a detail of the part indicated in Figure 2b.
As far as choice of material is concerned, indicator part 12 and indicator part 13 (the inner surface of hoist part 14) are chosen such that they do not, or hardly, wear down on one another during use. In the position indicated by number 18, indicator part 12 fits against the inner surface of hoist part 11, by, for example, bringing both legs of indicator part 12 towards one another, making it relatively easy to fit or replace.
Figure 3 a shows an embodiment which is similar to that of Figure 2a, wherein, once a set design value has been exceeded, i.e. after detection, the first indicator part 22 likewise deforms in the direction of hoist part 21. Indicator part 22 is reproduced in detail in Figure 3c. First indicator part 22 partially circumferentially extends as a U-profile along the inner circumference of hoist part 21. The profile 22 is joined to hoist part 21 by the rims 27, 28, wherein indicator part 22 cooperates with indicator part 23 which is provided on a hoist part 24 and extends along the inner circumference of hoist part 24. The hoisting force applied to hoist part 21 is in this case transmitted via the indicator parts 22, 23 to hoist part 24. Indicator part 22 is furthermore provided with a weakening 26 by local removal of material at the top of the U-profile, where the force is chiefly transmitted. If a hoisting force is greater than or equal to the set design force, the hoisting force between indicator parts 22, 23 ensures deformation chiefly at the point of the weakening 26.
Figures 4a-4d show an embodiment of the present invention comprising a hoist part 31 provided with a relatively soft first indicator part 32, which circumferentially extends as a narrow raised rim along the inner circumference of hoist part 31. Indicator part 32 is again embodied as a closed ring. Indicator part 32 here cooperates with hardened second indicator part 33, which is provided on a hoist part 34 and is embodied as a narrow raised rim or circumferential cam 33 extending along the inner circumference of hoist part 34. The hoisting force applied to hoist part 31 is in this case transmitted via the indicator parts 32, 33 to hoist part 34. If a hoisting force is greater than or equal to the set value, the surface pressure between indicator parts 32, 33 ensures a plastic deformation of indicator part 32. Indicator part 32, here a ring 32 placeable in hoist part 31, is provided on the side facing away from hoist part 31 with a circumferential cam or rim. In the event of overload the cam will plastically deform at the point where it abuts against (hardened) cam 33 of hoist part 34. The indicator parts 32, 33 are hardened such that wear is avoided. Preferably indicator part 33 is fully hardened, while indicator part 32 is hardened chiefly on the surface and is otherwise relatively soft. In a specific design the indicator part is made of steel with a yield point of approximately 210 MPa. Surface-hardening is applied to this steel. The hardened layer has attained a yield point of approximately 1800 MPa. The cam 33 is made of hardened steel with a yield point of approximately 400 MPa. These figures are indicative. The indicator parts for most embodiments will often be made of carbon steel. For example, a surface hardening such as laser hardening, induction hardening or nitriding will be applied to the indicator part. The second indicator part is usually hardened through at the point where the pressure force is exerted on the first indicator part, the contact surface, in a manner known by the person skilled in the art. As both indicator parts 32, 33 comprise rims which are pressed onto one another when a load is applied, and the rims are at an angle with respect to one another, a high point concentrated load will exist between both rims. Thus, it is be possible to cause a plastic deformation in one of the rims before causing structural weakening of the hoist parts.
Figure 5a shows the embodiment of Figure 4a with the difference that now the first indicator part 32 is embodied identically to part 33 as an integral part of hoist parts 31 and 34 respectively. The indicator parts can be produced using techniques such as forging and milling, following which (partial) hardening subsequently takes place. Again, as in the embodiment of figs 4, a high point concentrated load will develop.
Figure 6a shows the embodiment of Figure 5a with the difference that now the second indicator part 33 is embodied as a hardened part of hoist part 34 and not formed by a protruding part.
Figures 7a-7d show the embodiment of Figure Id with the difference that now the first indicator part 2 on hoist part 1 is embodied as a part which is weakened by local removal of material. Indicator part 2 here comprises a ring 2 with an inner surface 8 which forms a surface which is adjacent to cam or rim 3 of hoist part 4. Indicator part 2 furthermore has an outer surface 9 which is adjacent to hoist part 1. Ring 2 is provided with removed parts 10, consecutive in an axial direction. If there is a load greater than the set design value, i.e. the working load limit (WLL), in general twice the nominal load (WLL) (i.e. a hoisting force wherein the hoist part is elastically deformed but not yet plastically deformed), the removed parts 10 will be pressed shut by plastic deformation of the material of the ring 2. This will make wrong use or loading above the maximum hoisting force easy to perceive visually, while again no structural weakening will occur. Figures 8a-8c show the embodiment of Figure 4a-d with the difference that now both the first indicator part 32 is embodied as an integral soft part of hoist part 31 and the second indicator part 33 is embodied as a hardened part of hoist part 34 and is not formed by a protruding part or rim. In most cases, the surface will be hardened, as indicated above. Figures 9a- 9b show an embodiment of an alternative overload indicator. The operation is based on tensile strain in stead of pressure force. A first indicator part 90, comprising a breaking element 91, is fastened to a first hoisting eye 92 and a second hoisting eye 93. Breaking element 91 comprises a cover (or sleeve or casing) 91 with two cover halves 94, 95. These parts can for instance be screwed together. Eyes 92, 93 have extensions 98, 99 which extend into the cover 91. The extensions 98, 99 are mutually connected in cover 91 by means of a fracture element 97. Fracture element 97 can be accommodated in cover 91, placed as freely movable along its longitudinal axis. Fracture element 97 comprises a first fracture part 100, a second fracture part 101 and a breaking part 102. In a preferred embodiment, fracture element 97 cannot slide inside cover 91. In the event of overload, breaking part 102 will first constrict and then break in accordance with its design. Fracture part 101 will then be pulled up by eye 93 until it is retained by the top of cover 91. In order to retain fracture part 101, the inside of cover halve 95 may be tapered or it may have a cam or groove corresponding with a groove or cam of the fracture part 101. Retaining will provide a permanent indication. This means that coloured part 96 of the extension 99 will now stick out of the cover 91 so that overload is immediately visible. Preferably ends of screws of extension 98, 99 have been screwed into the fracture element 97. In one embodiment both cover parts 94, 95 are to be screwed together. A disadvantage in comparison to the previous embodiments based on pressure is that in most cases the overload indicator based on tensile strain will snap or at least elongate. This, when snapping, it will put an extra load on the indicator.
Figures 10a- 10b show an alternative embodiment of the alternative indication as shown in Figures 9a-9b with the difference that this embodiment has two breaking elements 90 in a hoisting eye as reproduced in Figures 9a- 9b. Both legs 103, 104 of a hoisting eye 105 are here provided with a breaking element.
Figures 1 Ia-I Ic show a further alternative indicator of the kind also reproduced in Figures 10a- 10b and 9a- 9b, based on tensile strain. Figure 1 Ib is a section XIb-XIb of Figure 11a and Figure 1 Ic is a section XIc-XIc of Figure 11a. Here the fracture elements 119 are embodied as rings 119, locally weakened by the removal of material, whereby lips 123 remain which are loaded under shear load. In this embodiment one set of cover parts 111, 112 is integrally formed at one end of each leg of eye 110. The other ends 113 are provided with a ring 119. Here the ring is mounted as removable/replaceable by means of a nut 120, for example. One end 113 extends in axial direction in a cover part 118. The fracture element 119 is in this case a ring 119 provided with an inner ring 121 and an outer ring 122, mutually concentrically connected by means of breaking parts 123. If the breaking parts fracture, the diameter of the fracture element will decrease, whereby the ends 113 can move axially in the cover (or sleeve part) 118 and a (possibly clamped) part of end 113 which was originally inside the cover 118 becomes visible. The two cover parts 111 and 118 can mutually form an accommodation space between them, in which the edge of the ring 119 is to be accommodated, so that axial movement of end 113 is prevented until fracture parts 123 break.
Figures 12a- 12c show an embodiment of the present invention as in Figures 1 Ia-I Ic with the difference that in this case it relates to a single embodiment instead of a double one. Figures 13 a- 13b show a hoisting eye 41 provided with a first indicator part 42 as a U in a part of the inner circumference of hoist part 41 and wherein the shape of the profile fits against hoist part 41 with the exception of upper edge 46 which lies clear from the surface of hoisting eye 41 and wherein upper edge 46 of indicator part 42 cooperates with indicator part 43 which is provided on a hoist part 44 and wherein the hoisting force applied to hoisting eye 41 is transmitted to hoist part 44 via the indicator parts 42, 43. At least a part of the inner surface of hoisting eye 41 can be hardened. If a hoisting force applied to hoisting eye 41 is greater than or equal to a set value, the hoisting force between indicator parts 42, 43 ensures fracture of upper edge 46 of indicator part 42. Indicator part 42 can have a weakening 49 to ensure deformation at the right place.
Figures 14a-14e show a hoisting device an overload indicator based on pressure force causing deformation. Hoist part 51 comprises a borehole 58 with a seating with, placed thereon, a first indicator part 52 which in this embodiment is embodied like fracture element 119 from Figures 11 and 12. Indicator part 52 cooperates with pin 53 in engagement with hoisting eye 54. Provided on pin 53 is a U-profile which at least partially circumferentially extends along the inner circumference of hoist part 51 and cooperates therewith to hold pin 53 in the outlined position with borehole 58. In the event of a load greater than a design limit, pin 53 will exert a pushing force on indicator part 52 of such a dimension that the fracture parts 60 break and the pin 53 can penetrate into hole 58. This is easily perceptible visually. This embodiment is based on pressure force, and provides an easily replaceable deforming element. In this embodiment, the element fractures.
Figures 15a-15d show the embodiment of Figure Ia with the difference that now the first indicator part 2 is embodied on hoist part 1 as a ceramic rim or cam 2 which circumferentially extends along the inner circumference of hoist part 1. In the event of a load greater than the set design value, indicator part 2 will pulverise at the point of engagement with indicator part 3. This makes wrong usage or loading above the maximum hoisting force easy to perceive.
Figures 16a-16d shows the embodiment of Figure Ia with the difference that now the first indicator part 2 is embodied on hoist part 1 as a cam or rim 2 which circumferentially extends along the inner circumference of hoist part 1 and wherein indicator part 2 comprises a crumple zone as made clear in Figure 16d. Again, the rim 2 which is at an angle with respect to the indicator part 2 provides a relative small contact service, providing a high point concentrated load which is clearly defined.
Figures 17a- 17c shows the embodiment of Figure Ia with the difference that now the first indicator part 2 on hoist part 1 is a kinkable or snapable element 2, embodied as a cam or rim which circumferentially extends along the inner circumference of hoist part 1 and wherein kinkable element 2 is here weakened by a notch 5. In the event of a load greater than the set design value the kinkable element 2 will buckle outwards. This kinking or bending can also be promoted or stimulated by a small bend in stead of notch 5.
Figures 18a-18d shows the embodiment of Figure Ia with the difference that now the first indicator part 2 on hoist part 1 is embodied as a bendable part 2 with a bendable lip or bendable lips 180 as shown in Figure 18d. Bendable part 2 circumferentially extends on the inner circumference of hoist part 1. In the event of load greater than the set design value the bendable lip or bendable lips 180 will bend outwards.
Figures 19a- 19b show an embodiment of the invention in which the hoist part 1 has an indicator part 2 which extends over part of the inner circumference of hoist part 1. In this embodiment, like the embodiment of figures 18a-18d, the indicator part 2 is insertable in the interior of link 1, but in this embodiment, the indicator part 2 is clamped between blocking parts 190. In this particular embodiment, the indicator part 3 has two sharp cutting edges 191. In order to prevent damage of the cutting edges during use, it has a small radius between the cutting edges, at the contact surface 193.
In operation, this contact surface will exert a pressure force on the lips 193 of indicator part 2. The lips 192 will start to bend when a hoisting force is exerted. When the load passes a certain design limit, the cutting edges will come in contact with the surface of the lips 192. When the load will get a little higher, these cutting edges 191 will cut through the surface of the lips 192 and the indicator part 2 will deform very rapidly.
In this embodiment, a cutting edge will come in contact after a first deformation, it will then cut through a surface layer of material, and the indicator will deform completely. The first deformation may be an elastic deformation.
An advantage of this particular embodiment is that the indicator part will have a very sharp response. As soon as a load above a designed indication level occurs, the indicator will give a visual indication.
Furthermore, in this embodiment the cutting edges are first protected by a contact surface and will only get in contact with the indicator surface when a load passes a set level. The design of the indicator part is such that this only occurs at a set level. The surface properties, especially local hardening, is such that the cutting edges cut through the surface above this set level.
Furthermore, the lips are engineered in such a way that after cutting though the surface layer, they will bend completely, giving a visual indication of overload above the set level. It should clear that the above description is adopted to illustrate the working of embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation, many variations will be evident to a person skilled in the art which come within the spirit and the scope of the present invention.

Claims

1. Hoisting device comprising a first hoist part and a second hoist part which engage in one another for transmitting a hoisting force and which is provided with an indicator part, wherein the indicator part:
- is permanently deformable by a pressure force applied by the transmitted hoisting force onto it by the first and second hoisting part,
- is located between the first and second hoist parts when the hoisting force is being transmitted, - is designed to permanently deform by a pressure force generated by a transmitted hoisting force which is greater than a minimum limit force, preferably a hoisting force greater than a working load limit for at least one of the hoist parts, and
- provides a visual indication of the application of a hoisting force above the minimum limit force.
2. Hoisting device according to claim 1, wherein the indicator part is designed to deform plastically by a pressure force generated by a transmitted hoisting force which is smaller than a maximum limit force, preferably by a pressure force generated by a transmitted hoisting force which is smaller than the hoisting force which substantially permanently deforms the first hoist part.
3. Hoisting device according to claim 1 or 2, wherein the first and second hoist parts are looped or hitches parts, and the indicator part comprises a cam on the first indicator part with at least part of its cam surface, in use, experiencing the pressure force from the second hoist part.
4. Hoisting device according to one of the preceding claims, wherein the indicator part is designed to deform plastically by a pressure force generated by a transmitted hoisting force which is smaller than the hoisting force which substantially elastically deforms the first hoist part.
5. Hoisting device according to one or more of the preceding claims, wherein the indicator part is an expendable part.
6. Hoisting device according to one or more of the preceding claims, wherein the indicator part is partially hardened.
7. Hoisting device according to one or more of the preceding claims, wherein the indicator part is surface-hardened at least at the point where the pressure force is exerted during use.
8. Hoisting device according to one or more of the preceding claims, wherein the indicator part comprises a rim which extends from the first hoist part.
9. Hoisting device according to one or more of the preceding claims, wherein the indicator part is a bendable element.
10. Hoisting device according to one or more of the preceding claims, wherein the indicator part is a crumple zone.
11. Hoisting device according to one or more of the preceding claims, wherein the indicator part is a kinkable element.
12. Hoisting device according to one or more of the preceding claims, wherein the indicator part is crushable by pressure force greater than a design force to be set.
13. Hoisting device according to one or more of the preceding claims, wherein the indicator part is placed on the first hoist part as removably insertable.
14. Hoisting device according to one or more of the preceding claims, wherein the indicator part is identifiable.
15. Hoisting device according to one or more of the preceding claims, wherein the indicator part comprises a hollow pipe.
16. Hoisting device according to one or more of the preceding claims, wherein the indicator part comprises a thin-walled open profile.
17. Hoisting device according to one or more of the preceding claims, wherein the indicator part is weakened by local removal of material.
18. Hoisting device according to one or more of the preceding claims, wherein, once the set pressure force has been exceeded, the indicator part consists of two or more parts.
19. Hoisting device according to one of the preceding claims, wherein the second hoist part is provided with a second indicator part and the first and second indicator parts exert the pressure force on one another when transmitting the hoisting force.
20. Hoisting device according to one of the preceding claims, wherein the second indicator part is designed not to deform when the first indicator part plastically deforms.
21. Hoisting device according to one or more of the preceding claims, wherein by cooperation of the first and second indicator parts the surface pressure between them is amplified.
22. Hoisting device according to one or more of the preceding claims, wherein the second indicator part is hardened in its entirety.
23. Hoisting device according to one or more of the preceding claims, wherein the second indicator part comprises a rim which extends from the second hoist part.
24. Hoisting device according to one or more of the preceding claims, wherein the first indicator part comprises a rim which extends from the second hoist part and the second indicator part comprises a rim which extends from the second hoist part, wherein during the hoisting force the rims are crossed over one another.
25. Hoisting device according to one or more of the preceding claims, wherein the second indicator part comprises a spring, the bias of which is settable.
26. Hoisting device according to one or more of the preceding claims, comprising a converter which provides a further easily perceptible indication.
27. Hoisting device according to claim 26, wherein the converter comprises a light source or a sound source, or else comprises a further source for emitting a sensually perceptible signal.
28. Hoisting device according to preceding claims 26 or 27, wherein the converter can be switched on and off.
29. Hoisting device according to one or more of the preceding claims, wherein the first hoist part has been chosen from the group consisting of the end of a chain, the end of a cable, the end of a hoisting belt, a coupling link, a hoisting hook and a hoisting eye.
30. Hoisting device according to one or more of the preceding claims, wherein the hoisting force puts the first indicator part under shear load, whereby said indicator part deforms or breaks.
31. Hoisting device according to one or more of the preceding claims, wherein the first or second indicator part is provided with a mark, preferably a unique mark such as a serial code.
32. Hoisting device according to claim 31, wherein the first and/or second hoist part is provided with a mark, preferably a unique mark such as a serial code, wherein the indicator part mark and the hoist part mark have a mutual connection.
33. Hoisting device comprising first and second hoist parts which transmit a hoisting force, wherein the hoist parts are mutually connected by means of at least one breaking element which, under tensile load by the hoisting force, deforms or breaks, and the hoist parts are mutually connected by means of a connecting part which remains intact when the breaking element deforms or breaks.
34. Hoisting device comprising a hoist part for transmitting a hoisting force and which is provided with an indicator part, wherein the indicator part shatters at least at the point of the pressure force due to a pressure force applied by the transmitted hoisting force.
35. Hoisting device comprising a hoist part for transmitting a hoisting force and which is provided with an indicator part, wherein the indicator part is permanently deformable by a pressure force applied by the transmitted hoisting force.
36. Hoist part, obviously suitable and intended as hoist part for a hoisting device according to one of the preceding claims.
37. Indicator part, obviously suitable and intended as first indicator part for a hoisting device according to one of the preceding claims.
38. Hoist part provided with one or more of the characterising measures described in the appended description and/or shown in the appended drawings.
-o-o-o-o-o-o-
PCT/NL2007/050345 2006-07-11 2007-07-11 Hoisting device with overload detection Ceased WO2008007961A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL2000139A NL2000139C2 (en) 2006-07-11 2006-07-11 Hoisting device with overload detection.
NL2000139 2006-07-11

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WO2008007961A3 WO2008007961A3 (en) 2008-03-13

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9067766B1 (en) 2013-09-16 2015-06-30 Jergens, Inc. Hoisting device and system and method for using the same
EP3263505A1 (en) 2016-06-30 2018-01-03 Intelprop S.A. Load control device, in particular for a lifting ring
WO2019023742A1 (en) * 2017-07-31 2019-02-07 Mitchell Lee Lewis Safety overload link
WO2020167147A1 (en) * 2019-02-14 2020-08-20 Łasżkiewicz Grzegorz Fall indicator
FR3144012A1 (en) * 2022-12-23 2024-06-28 Tractel Sas Hanging loop with fall arrest indicator

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US3033033A (en) * 1958-11-24 1962-05-08 W C Dillon & Company Inc Force measuring apparatus
DE2055253C3 (en) * 1970-11-03 1979-02-01 Rud-Kettenfabrik Rieger & Dietz Gmbh U. Co, 7080 Aalen Lashing or sling chain
DE2901936A1 (en) * 1979-01-19 1980-07-31 Autoflug Gmbh LOAD INDICATOR FOR SEAT BELTS
JPS56142439A (en) * 1980-01-03 1981-11-06 Esu Tee Aa Esu Soc Tech Dasets Fatigue stress indicator
US4578941A (en) * 1984-08-27 1986-04-01 Emerson Electric Co. Load carrying device
GB2274899B (en) * 1993-02-03 1997-06-04 Hugh Michael Oppen Pratt Load insulator

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9067766B1 (en) 2013-09-16 2015-06-30 Jergens, Inc. Hoisting device and system and method for using the same
US9302889B2 (en) 2013-09-16 2016-04-05 Jergens, Inc. Hoisting device and system and method for using the same
EP3263505A1 (en) 2016-06-30 2018-01-03 Intelprop S.A. Load control device, in particular for a lifting ring
WO2018002136A1 (en) 2016-06-30 2018-01-04 Intelprop S.A. Load indication device, in particular for a lifting ring
WO2019023742A1 (en) * 2017-07-31 2019-02-07 Mitchell Lee Lewis Safety overload link
US11731861B2 (en) 2017-07-31 2023-08-22 Mitchell Lee Lewis Safely overload link
AU2018310750B2 (en) * 2017-07-31 2023-10-26 Mitchell Lee Lewis Safety overload link
WO2020167147A1 (en) * 2019-02-14 2020-08-20 Łasżkiewicz Grzegorz Fall indicator
FR3144012A1 (en) * 2022-12-23 2024-06-28 Tractel Sas Hanging loop with fall arrest indicator

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Publication number Publication date
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NL2000139C2 (en) 2008-01-14

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