GB1581725A

GB1581725A - Appliances having cooperating working jaws

Info

Publication number: GB1581725A
Application number: GB5236676A
Authority: GB
Original assignee: Pressmaster AB
Current assignee: Pressmaster AB
Priority date: 1976-12-15
Filing date: 1976-12-15
Publication date: 1980-12-17
Also published as: JPS5377400A; FR2374142B1; DE2755482C2; JPS6246315B2; FR2374142A1; DE2755482A1

Description

(54) IMPROVEMENTS RELATING TO APPLIANCES HAVING COOPERATING WORKING JAWS (71) We, PRESSMASTER AB of Sergels Torg 12, Stockholm, Sweden, a Swedish company do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an appliance comprising two working jaws, each carried by a respective limb member, the limb members being by driving means movable between a first end position for maximum opening of the jaws and a second end position for maximum closing of the jaws, each limb member forming, or being part of, a respective force transmitting path.

An appliance according to the invention is an appliance for handling (e.g. gripping or holding) or performing an operation (e.g.

pressing, crimping, incising or cutting) on an article accommodated between the working jaws of the appliance, the limb members of which are movable relative to each other by a pivoting movement (tong-type appliance), such an appliance being hereinafter called an "appliance of the kind specified". Tongs, pliers, clamps, and the like are all examples of an appliance of the kind specified. The second end position is the position in which the jaws maximally grasp the article or bear one against the other.

The drive means may be e.g. a handle.

By "working jaw" is meant that particular part which is adapted for the desired operation, e.g. by being provided with operative means such as dies or grooves, whereas by "limb member" is meant the part which carries the working jaw. By a "force transmitting path" of the appliance is to be understood that chain of interacting and interconnected structural parts of the appliance which are situated between a force inlet part (such as one handle) and a force outlet part (such as a jaw associated with said handle) and adapted to transmit, and in use transmitting, force from the force inlet part to the force outlet part.

It will be readily understood that it is generally desirable to have the facility to treat in a given appliance articles within as large a range of dimensions as possible, thus obviating the need to procure appliances in several sizes, for treating articles with widely differing dimensions. It will be appreciated that the said range is defined by the difference between the maximum and minimum opening of the working jaws.

In some instances, i.e. with the crimping of so-called terminal ferrules onto the ends of electrical conductors, it is further desirable that greater force is applied to larger articles than to smaller ones, but it will be appreciated that such a demand also may arise in other appliances of the kind specified; e.g. a vice should squeeze harder a larger - and probably heavier - article than a smaller one.

In conventional appliances of the kind specified this however is not the case, and substantially identical squeezing force is applied both to large and small articles.

One aim of the present invention is to provide an appliance of the kind specified which is improved in the sense that the effective force which is applied to the article when the driving means approaches its second end position for closed jaws is greater in the case of a large article than when a smaller article is handled.

The invention provides a tong-like appliance of the kind specified comprising two working jaws, each provided with a plurality of spaced apart support plates positioned one behind the other in axial direction of an article to be handled between the jaws, so as to provide gaps, the width of each gap being equal to at least the thickness of one said support plate, each support plate having one strip-shaped engagement face and substantially half of said engagement faces on each jaw being contained in a first surface and inclined to a plane of symmetry of the respective jaw from a first side thereof, and the remainder of the said engagement faces on the respective jaw being contained in a second surface and inclined to said plane of symmetry from a second side thereof, there being for each engagement face on one jaw an associated opposite engagement face on the other jaw, the arrangement being such that in the course of mutual approach move mcnt of the jaws the support plates of one jaw penetrate into said gaps between the support plates of the other jaw, each working jaw being carried by a respective limb member forming, or being part of, a respective force transmitting path at least one of the limb members being by driving means movable in a plane of mutual approach of the working jaws between a first end position for maximum opening of the working jaws and a second end position for maximum closing of the working jaws, wherein at least one of the working jaws is pivotally connected to the associated limb member so that the support plates on the working jaws, after first engagement with each other, automatically align themselves and the two working jaws as the limb members are moved closer together allowing the working jaws to get aligned substantially parallel to each other before the second end position is reached.

A resilient member may be interposed in the force transmitting path (as hereinbefore defined) to at least one of the working jaws.

It may be positioned for instance between a limb member and the associated working jaw or between a limb member and an associated driving means, or between a limb member and an associated stationary part of the appliance supporting the respective limb member.

In the prior art tong-type appliances the working jaws approach one another in inclined disposition. If the treated article accommodated between the jaws prevents the jaws from contacting one other in the second end position, which is often the case in practice, the jaws keep a certain mutual inclination even in the second end position.

This makes the co-operation of operative means on the respective jaws difficult, if these operative means in their working position have to be aligned in some predetermined way, because the degree of inclination of the jaws in the second end position varies with the dimension of the article which is accommodated between the jaws. Consequently, the more complex and more expensive vice-type appliances with translatorial, i.e. parallel motion of the jaws must be used in many cases.

The applicant has in the British published patent application No. 1,523,160 divulged working jaws of a noval type, which will be described in more detail in connection with the following description of exemplary embodiments, and which can be used in vice-type or tong-type appliances, but in the latter case call for greater spacing between the elements defining their operative means.

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figures la to id demonstrate the principle of the invention: Figure 2, is a diagram showing the development of the effective force in the resilient member; Figure 3 is a front elevation of a pair of crimping pliers adapted according to the present invention; Figure 4 shows in greater detail the working jaws of the pliers according to Figure 3, and Figure 5 shows one limb member of pliers according to Figure 3 in greater detail and in a slightly modified execution.

In Figures la to id a vice-like appliance is diagrammatically shown which has two working jaws 10, 20, of which the jaw 20 is movable with a translatory movement towards and away from the stationary jaw 10. This translatory movement is controlled in a way knownperse by a driving means 30, such as a handle pivotable about a pivot 35, between a first end position for the maximum opening of the jaws 10, 20 second end position for the maximum closing of the jaws 10, 20 (Figure ib, lid). The driving means may also be partially pivoted into any intermediate position, (Figure la, inc). The stationary jaw 10 is by means of a limb member 13, which in this instance represents the force receiving member, or at least a substantial part thereof, anchored on a stationary part of the appliance, such as, the stationary handle 11 of the pliers-like appliance shown in Figure 3.

In Figure la there is between the jaws 10, 20 shown a first object A which is assumed to be just so large as to occupy the space between the jaws 10 and 20 without any compression of a spring 32 interposed between the jaw 20 and a push rod 33, when the driving means 30, which in a known manner, not shown in the drawing, controls the movements of the push rod 33, has been moved from its first end position (assumed vertical in the drawing) by a small angle a and has in its turn moved the push rod 33 through a small distance e. The force transmitting path of the jaw 20 is in this instance the spring 32, the push rod 33 and the driving means 30.

The spring 32 has a natural length a. By moving the driving means 30 to its second end position for maximally closed jaws, as shown in Figure ib, the spring 32 is maximally compressed by a distance b and assumes its shortest length c in this instance and acts with its maximum force in this instance on the object A.

According to Figure ic a smaller object B is placed between the jaws 10, 20. To achieve now any engagement at all, the push rod 33 has first to be moved through a further distance d which obviously is the difference between the diameters of articles A and B.

This is achieved by more extensive actuation of the driving means 30 (swinging it through an angle ss). When the driving means 30 is further swing into its second end position (Figure lid), the push rod 33 advances through a further distance b which obviously is smaller than the distance b in Figure ib; and the spring 32 is compressed to a lengthy which is greater than the length c in Figure ib. Consequently, the smaller article B is compressed with a weaker force than the larger article Pc.and A.

In Figures ic and id there is further diag- rammatically shown one way (of a number of other possible ways) of prestressing the spring 32. The spring 32, which now is supposed to have a somewhat greater free length than a, is slipped over a guide rod 34 which has a first end stop 34A (embedded in the jaw 20) and a second end stop 34b. The guide rod 34 passes through an opening in the front face of the push rod 33, and the second end stop 34B is disposed in a hollow space 33A in the push rod 33. The free length of the guide rod 34 in relation to the somewhat longer free length of the spring 32 defines the degree of pre-stressing of the latter.

It is obvious that the pre-stressing is advisable in particular for the smaller articles B, as is clearly evident from the diagram in Figure 2, where on the axis X movements or distances and on the axis Y the power effects of the resilient member are plotted. For identical magnitudes, identical reference symbols as in Figures la to id are used, even if the scale is not exactly the same. The full lines IB, ID refer to the situations according to Figures ib and id, respectively, when no pre-stressing of the spring 32 is assumed, and the dashed lines I'B, I'D refer to the same situations, when the spring 32 is prestressed by a force S, plotted on the axis Y. The development of the power effect of the resilient member is for the sake of simplicity assumed to be linear (straight lines IB, ID etc.). At I"B is shown how the force development takes place in case of a stepwise working resilient member where L1, at the intersection of the axes X, Y denotes the first, and L2, on the axis X, the second end position of the driving means 30. It will be appreciated that the spring 32, with the same effect, can be interposed between the stationary jaw 10 and its support, and of course also that both jaws 10, 20 can be arranged in such a manner.

In Figure 3 a pair of crimping pliers is shown with a stationary handle 11 and a pivotal handle 21 which is the driving means of the appliance. The movement of the handle 21 is with the aid of a cam-and-camfollower-mechanism 21B, 31B, the construction of which lies outside the scope of the invention, transferred to a movable limb member 22 which by means of a pivot pin 50 is pivoted to a body 40 of the tool, to which the stationary handle 11 is rigidly attached.

Although in the drawing a pair of pliers with a variable force transmission ratio between the handle 21 and the limb member 22, in accordance with appliant's British published patent specification 1,500,101 is shown it will be understood that the present invention is by no means restricted to this specific type of tool. Also pivotally mounted on the pivot pin 50 is a limb member 51 which carries a working jaw 110. A co-operating working jaw 120 is mounted on the limb member 22.

Between the limb member 51 and the body 40 there is interposed a block 41 of elastomeric material, such as natural or synthetic rubber, or polyurethane. A slot 52 (Figure 5) in the limb member 51, co-operating with a pin 53 on the body 40, limits the pivotal movement of the limb member 51 relative to the body 40 or the handle 11 and defines the mutual relationship of these parts in the unoperative condition of the appliance, i.e.

when no stress is put on the limb member 51.

It will be readily understood that the amount of a possible pre-stressing of the block 41 is defined by appropriately selecting the dimensions of the block 41 relative to the dimensions of the space between the body 40 and the limb member 51 into which the block 41 is fitted. The movable handle 21 and the limb member 22 are in phantom shown in their first end positions 21', 22' for maximally open jaws.

Figure 5 shows means for selective application of a closing force and/or of a prepressing force on the elastomeric block 41. A movable plate 54 is interposed between the body 40 of the tool and the elastomeric block 41. An adjustment screw 55 is arranged in the hollow interior of the body 40 in a stationary nut element (not shown). By moving the plate 54 in upward direction in Figure 5, pre-tension is applied to or increased in the elastomeric block 41, as the abutment of the pin 53 on the one end of the slot 52 prevents such a movement of the plate 54 to be translated to a swing of the limb member 51 in the direction towards the limb 22.

The working jaws 110, 120 are shown to a larger scale and in more detail in Figure 4.

Each of the jaws has two groups of engagement faces 111, 121, respectively. The engagement faces in each group are mutually parallel and also parallel to the engagement faces in the group which is oppositely dis posed on the other working jaw. Jaws of this kind are described in more detail in applicant's earlier mentioned British published patent specification 1,523,160. Between two adjacent support plates such as 11 1A which carry the engagement faces (gaps) such as 112, 122 are provided the width of which is at least as large as the thickness of the support plates. In appliances where the jaws are rigidly connected to their limbs the actual width of the gaps 112, 122 depends on whether the two jaws 110, 120 perform a tong-like pivotal movement (as according to Figure 3) or a vice-like parallel movement (as according to Figures la to lid).

The construction of jaws according to Figure 4 results in the two jaws forming a closed channel when approaching one another, which channel has a varying cross-section and thus is able to accommodate articles of different dimensions, and to contact them from all four sides.

In Figure 3 a particularly advantageous mounting of the jaws 110, 120 is shown.

Each jaw is, by means of a respective lug 11 0A, 1 20A (Figure 4) mounted on a respective pivot pin 22A, 51A. The lug 120A is located essentially in the central region of the breadth of the jaw 120 and its thickness is smaller than this breadth, so that on both sides of the lug 1 20A portions of the rear face 120C of the jaw 120 lie free. In the limb members 22, 51 recesses are arranged for accommodating the lugs, also essentially in the central region of the breadth of the respective limb member, and having themselves such a breadth dimension that their side walls encompass the lug from both sides and guide it. In the said side walls and in the lug itself aligned holes are provided for the pivot pin 22A, 51A. It will be understood, however, that a pivotal connection between a jaw and a limb member can also be achieved in some other manner known per se, particularly when the respective limb member is composed of two halves, e.g. by means of at least one circular or arcuate groove, say in the said side wall, and a corresponding ridge on the lug, or vice versa. Thus the two jaws 110, 120 and their support plates, such as iliA, can align themselves automatically, when, after a first engagement shown in Figure 3, the limb members 22, 51 are moved closer together. The gaps 112, 122 may therefore, even in the case of a tong-like movement, be narrower than when the jaws 110, 120 are mounted fast on the respective limb members. It will be appreciated that making the said gaps rather narrow, tKe support plates on each jaw, after first contact in the position illustrated in Figure 3, will effectuate an aligning of the jaws as the flanks of the support plates will glide along each other when the jaws are further closed from the position shown in Figure 3.

The pivotal mounting is therefore specially profitable when used in connection with the above described resilient member arrangement, which is another advantage resulting from the combination of the two aspects of the present invention. Such a mounting, or the pivotal mounting of at least one of the working jaws, allows furthermore, disregarding the actual type of the working jaws, to compensate for the pivotal movement of the limb about the pivot pin 50, to relieve the said pivots 22A, 51A from too high a stress.

surfaces 22E, 51E of the limb members 22, 51 which define outward edges of the said side walls are curved at a radius centered at the respective pivot pin 22A, 51A, and the openings 110B, 120B for these pivots 22A, 51A in the lugs 110A, 120A are disposed from the rear faces 110C, 120C of the respective working jaw 110, 120 at a distance equal to said radius. Thus the said rear faces 110C, 120C bear against said curved surfaces 22E, 5 lE in each position of the working jaws 110, 120. The surfaces 51F of the limb member 51 of the embodiment shown in Figure 5 are roof-shaped, with one "slope" 51F' preferably giving support along its entire length to the jaw 110 in the position where the two limb members 22, 51 are completely closed one upon another.

In crimping pliers and similar appliances it is customary to provide a pawl-and-ratchet mechanism which does not permit opening of the jaws before the compressing operation performed by the tool has been completely finished. A mechanism of this kind is in more detail described in applicants' earlier and mentioned published British patent specification 1,500,101 comprises a ratchet 24 and a pawl 34, shown in phantom in Figure 3. It will be appreciated that the present invention is particularly applicable to tools provided with a mechanism with the above stated function (disregarding the actual construction of such a mechanism), because thus the driving means is always actuated until it reaches its second end position and consequently articles of mutually identical dimensions are always subjected to identical compressing forces.

It will be understood that although the invention has been described in connection with a pair of crimping pliers, it is in no way limited to such a tool, but can with advantage be applied to other appliances having two working jaws, such as pliers or clamps.

It will also be appreciated that the mounting of the working jaws 110, 120 on the pivot pins 22A, 5 IA and possibly supported on the curved surfaces 22E, 5 lE provides the same advantage, i.e. the possibility to make the gaps 112, 122 narrower, also in tools not provided with a resilient block 41, but having working jaws of this kind moved pivotally instead of parallel to each other, or in tools where the resilient member is interposed in the power transmitting path in a different location, where it does not affect the mutual position of the two working jaws. From inspection of Figure 3 it will be apparent that the intended function of the resilient member is also achieved if this is placed e.g.

in either of the locations L, M on one or both of the handles 11, 21 (the pivot pin 50 being placed nearer the outer periphery of the respective handle). It will also be appreciated from Figure 3 that the resilient block 41, or any other resilient member, can also be placed on the limb member 22 e.g. by turning the shown disposition through approximately 1800 around the pivot 50.

It is also obvious that a resilient member may be simultaneously interposed or incorporated in each of the force transmitting paths.

It will further be understood from the preceding explanation that at the beginning of a squeezing operation of the jaws, large and small articles alike will be influenced substantially equally because at that stage the compression of the resilient member begins.

In the case of small articles, the point of this beginning lies close to the second end position of the drive means, so that only a relatively moderate increase in the compression of the resilient member will be achieved before the driving means definitively stops.

In the case of larger articles, the first engagement between the jaws and the article will take place already when the driving means still is relatively remote from its second end position and is in or close to its first end position. The compression of the resilient member will continue during the travel of the driving means and reaches a higher degree than in the former case, before the driving means is finally stopped in the second end position.

The resilient member can preferably have a predetermined non-linear operating characteristic and e.g. comprise or consist of a bundle of leaf springs of which the individual members are successively engaged, as the compression of the bundle proceeds (step-wise working resilient member).

Conveniently, the resilient member can be pre-stressed in its initial position so that its starting effect lies already above the zerovalue and even the smallest article receives a predetermined minimum compression. The present invention is particularly suitable for use in connection with working jaws accord ing to our above-mentioned published Brit ish patent application No. 1,523,160 and in an appliance provided with a mechanism compelling the driving means to completely finish each stroke, as e.g. described in our British published patent application No.

1,500,101 and 1,523,160.

WHAT WE CLAIM IS:1. A tong-like appliance of the kind specified comprising two working jaws, each provided with a plurality of spaced apart support plates positioned one behind the other in axial direction of an article to be handled between the jaws, so as to provide gaps, the width of each gap being equal to at least the thickness of one said support plate, each support plate having one strip-shaped engagement face and substantially half of said engagement faces on each jaw being contained in a first surface and inclined to a plane of symmetry of the respective jaw from a first side thereof, and the remainder of the said engagement faces on the respective jaw being contained in a second surface and inclined to said plane of symmetry from a second side thereof, there being for each engagement face on one jaw an associated opposite engagement face on the other jaw, the arrangement being such that in the course of mutual approach movement of the jaws the support plates of one jaw penetrate into said gaps between the support plates of the other jaw, each working jaw being carried by a respective limb member forming, or being part of, a respective force transmitting path, at least one of the limb members being by driving means movable in a plane of mutual approach of the working jaws between a first end position for maximum opening of the working jaws and a second end position for maximum closing of the working jaws, wherein at least one of the working jaws is pivotally connected to the associated limb member so that the support plates on the working jaws, after first engagement with each other, automatically align themselves and the two working jaws as the limb members are moved closer together allowing the working jaws to get aligned substantially parallel to each other before the second end position is reached.

2. An appliance according to Claim 1, wherein on the limb member bearing the pivotable working jaw at least one bearing face, facing the adjacent rear face of the said working jaw, is curved or has two planar surfaces extending at an obtuse angle to each other, the arrangement being such that said rear face at least in the said second end position of the respective working jaw bears against said bearing face on the limb member, whereby said pivotal connection is relieved from too high stresses.

3. An appliance according to Claim 1 or 2, wherein a lug protrudes from the rear face of the pivotal working jaw, the thickness of the lug being smaller than the breadth of the said rear face, the lug being located substantially in the central zone of said breadth.

4. An appliance according to Claim 3 when appended to Claim 2, wherein said bearing face is defined by an edge of the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. where the resilient member is interposed in the power transmitting path in a different location, where it does not affect the mutual position of the two working jaws. From inspection of Figure 3 it will be apparent that the intended function of the resilient member is also achieved if this is placed e.g. in either of the locations L, M on one or both of the handles 11, 21 (the pivot pin 50 being placed nearer the outer periphery of the respective handle). It will also be appreciated from Figure 3 that the resilient block 41, or any other resilient member, can also be placed on the limb member 22 e.g. by turning the shown disposition through approximately 1800 around the pivot 50. It is also obvious that a resilient member may be simultaneously interposed or incorporated in each of the force transmitting paths. It will further be understood from the preceding explanation that at the beginning of a squeezing operation of the jaws, large and small articles alike will be influenced substantially equally because at that stage the compression of the resilient member begins. In the case of small articles, the point of this beginning lies close to the second end position of the drive means, so that only a relatively moderate increase in the compression of the resilient member will be achieved before the driving means definitively stops. In the case of larger articles, the first engagement between the jaws and the article will take place already when the driving means still is relatively remote from its second end position and is in or close to its first end position. The compression of the resilient member will continue during the travel of the driving means and reaches a higher degree than in the former case, before the driving means is finally stopped in the second end position. The resilient member can preferably have a predetermined non-linear operating characteristic and e.g. comprise or consist of a bundle of leaf springs of which the individual members are successively engaged, as the compression of the bundle proceeds (step-wise working resilient member). Conveniently, the resilient member can be pre-stressed in its initial position so that its starting effect lies already above the zerovalue and even the smallest article receives a predetermined minimum compression. The present invention is particularly suitable for use in connection with working jaws accord ing to our above-mentioned published Brit ish patent application No. 1,523,160 and in an appliance provided with a mechanism compelling the driving means to completely finish each stroke, as e.g. described in our British published patent application No.

1,500,101 and 1,523,160.

respective limb member adjacent said lug, and said lug is pivotally counter-sunk into said limb member.

5. An appliance according to Claim 4 wherein said pivotal connection is provided by a pivot pin passing through aligned holes in said lug and the associated limb member.

6. An appliance according to any one of the preceding claims wherein a resilient member is interposed in the force transmitting path (as hereinbefore defined) to at least one of the working jaws.

7. An appliance according to Claim 6 wherein the resilient member is positioned between a limb member and the associated working jaw, or between a limb member and an associated driving means, or between a limb member and an associated stationary part of the appliance supporting the respective limb member.

8. An appliance according to Claim 6 or 7 wherein the resilient member is a spring or a block of elastomeric material.

9. An appliance according to Claim 8 wherein the elastomeric material is natural or synthetic rubber or polyurethane.

10. An appliance according to any one of Claims 6 to 9 wherein the resilient member has predetermined non-linear operating characteristics.

11. An appliance according to Claim 10 wherein the resilient member is a step-wise working resilient member.

12. An appliance according to Claim 11 wherein the resilient member is a bundle of leaf springs of which the individual members are engaged successively as the compression of the bundle procecds.

13. An appliance according to any one of Claims 6 to 12 wherein the resilient member is prestressed in its initial position so that its starting effect lies already above the zero value.

14. An appliance according to any one of Claims 6 to 13 including means for adjustable prestressing of the resilient member.

15. An appliance according to any one of Claims 6 to 14 provided with a pawl-andratchet mechanism which does not permit opening of the jaws before the compressing operation performed has been completely finished.

16. An appliance according to any one of Claims 7 to 15, wherein the first limb member bearing the first working jaw is drivable by a pivotable first handle between the said two end positions, the second limb member bearing the second working jaw is associated with a second stationary handle and the resilient member is arranged between the second limb member and the stationary handle.

17. An appliance according to Claim 16 wherein both limb members and the stationary handle are attached to a common pivot element.

18. An appliance according to Claim 16 or 17 wherein on the second limb member and on the stationary handle co-operating stop means are provided which means define the mutual relationship between these two elements in an operative condition.

19. An appliance according to any one of the preceding claims with a tong-like approaching movement of the two limb members, wherein said gaps between said support plates are narrower than in an appliance of the kind specified and with a tong-like movement of limb members with rigidly mounted working jaws thereon.

20. An appliance of the kind specified, constructed, arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in Figure 3, Figure 3 and 4, Figure 3 and 5 or Figure 3, 4 and 5 of the accompanying drawings.