GB1582684A

GB1582684A - Screens

Info

Publication number: GB1582684A
Application number: GB11558/78A
Authority: GB
Original assignee: N Greening Ltd
Current assignee: N Greening Ltd
Priority date: 1978-03-23
Filing date: 1978-03-23
Publication date: 1981-01-14
Also published as: ZA791226B

Description

(54) IMPROVEMENTS IN OR RELATING TO SCREENS (71) We, N. GREENING LIMITED, A British Company of Britannia Works, Bewsey Road, Warrington, WA5 SJX, 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 invention relates to screens such as are used for screening aggregates and is particularly applicable to screen panels of the kind formed by a plurality of looped wires secured side-by-side to define the apertures.

It is known to provide such a screen panel by forming loops in individual lengths of wire and then threading them onto tie rods extending through the loops. Deformation of each loop to a predetermined small misalignment of inter-loop parts produces a "joggle" at each loop and sets the widths of slits or apertures between adjacent wires.

The width of such slits can be accurately determined by pressing the sides of the loop toegther, before of after assembly onto the tie rods. Often, such a screen panel will have ferrules rivetted onto free ends of the rods. A suitable rubber or like strip attached to the ends of the tie rods, with or without ferrules, may be preferred in fitting the panel to be vibrated in a conventional screening machine.

Although such panels afford very accurate initial aperture sizing, problems arise because adjacent wires may be subject to relative movement and wear due at least partly to flexing of the screen when it is vibrated in use. The flexing is higher if the unsupported span of the screen is large unless steps are taken to adjust its resistance to flexing. In this respect it should be noted that it is known to increase the screen stiffness by using larger cross-sections of or reduced spacings between the tie rods. Such measures are often unsatisfactory because of the consequent increase in vibratory mass due to the extra weight of the tie rods and its negating effect on intended improvement.

An object of the present invention is to provide an apertured panel of the kind referred to and in which the above mentioned problems are mitigated or eliminated.

According to one aspect of the present invention an apertured panel comprises a plurality of wire members having loops at intervals along their lengths and spaced, preferably by the configuration of their loop portions, so as to define slit apertures between adjacent wires, the wires being connected together to form a panel by tie rods, tubes or the like extending through their aligned loops, outer parts of at least some of said aligned loops being secured to a rib member or members extending externally thereof and transversely to the wires, usually, but not necessarily, the rib member which may be solid, will lie parallel to the tie rod.

For wedge-section wire, upper parts of the adjacent loops are preferably in contact one with another.

Reinforcingly interconnecting the bottoms of the loops has the effect of limiting any relative movement of the loops so reducing chafing and also increasing the resistance to flexing, forming as it were the lower span of a beam. Any increase in weight due to the addition of the rib yields a much greater increase in resistance to flexing than the equivalent weight increase involved in merely increasing the size or number of tie rods.

Furthermore, the depth and/or section of the rib can be selected according to particular applications and desired unsupported spans. Although a rectangular section is preferred an inverted T-section might be employed or other suitable sections.

According to a second aspect of the invention a method of making an apertured panel of the first aspect comprises assembling a plurality of wires having loops at intervals along their lengths onto tie rods, tubes or the like extending through aligned loops such that the parts of the wires between the loops are spaced to define desired slit apertures, aligning a rib member with the loops and securing mating portions of the rib member and loops together by application of mutual pressure and/or heat.

In preferred embodiments the rib is welded to the loops, conveniently electrically pressure welded. However, it has been found that satisfactory results can be achieved where, due to the combination of heat and pressure, the material of the rib and loops is merely compounded or forged, usually with complimentary deformation of mating parts thereof.

The rib need not extend across the whole width of the screen or panel, but it is envisaged that in some embodiments the rib will extend at least to the end of the screen and be secured, perhaps welded to the projecting end of the tie rod and/or to any sleeve or fermle located thereupon. Where the rib is to be secured directly to the rod, it may be bent or stepped as required, any rubber strip being corresponding recessed as required to accommodate the rib/and rod end.

It is further envisaged that the rib may be stopped short of the end of the panel say where it is required for the rubber support strip to overlap the edge of the panel.

An embodiment of the invention will now be described by way of example only and with reference to the accompaning drawings in which: Figure 1 is a perspective view of a screen fromed from a plurality of looped wires.

Figure 2 is a side view of the looped wire.

Figure 3 is a plan view corresponding to Figure 2, and Figure 4 is a side view of an end portion of the screen showing a modification.

Figure 1 shows a portion of screen comprising a plurality of looped wedge-section wires 10, secured together side-by-side by tie bars 11 extending through depending loops 12 of the individual wires. Apertures or slits 13 are provided between the adjacent wires due to predetermined small misalignment of inter-loop parts giving spacing of the remainder of the wire when the loops are in contact. The width of the slits 13 is accurately determined by deformation of the loots producing a "joggle" at each loop.

Figures 2 and 3 illustrate suitably deformed wires.

When a required number of wires 10 have been assembled for a desired screen size, a ferrule or sleeve 14 is secured upon the end of the tie bar, e.g. by rivetting or peening over the end of the tie bar, so as to clamp the wires together.

A rib 15, shown as being of rectangular section, is then placed along the lowermost edges of the loops, extending parallel to the tie bar and is secured to the loops, typically but not necessarily by welding. It has been found that a satisfactory joint between the rib and loops is achieved using an electrical/ resistance heating technique with simultaneous application of mutual pressure to the loops and rib. Although it is preferable to weld the rib to the loops in this way it is possible that a satisfactory bond will be achieved with the parts being merely forged or compounded.

In order to reduce the possibility of distortion of the screen and misalignment of the rib relative to the loops, it is convenient to lay the screen with its usually uppermost surface lying on a plate electrode of the electrical/resistance heating apparatus, align the rib above the loops using a suitable jig, and then apply pressure and the required electrical current to the rib by means of a strip-like second electrode of the machine.

It is envisaged however that improved resistance to flexing of the screen and/or relative displacement of the wires would be achieved by securing, say welding or forging the interior portions of the loops to the tie bar in addition to securing their outer portions to the rib. This might conveniently be achieved by using the tie bar as the first electrode instead of the plate on which the screen is laid.

It will be appreciated that the rib need not be provided at every tie bar/loop location and also that it need not extend across the entire width of the screen. In particular, where the rubber support strip must overlap the edge of the screening surface the rib will usually end short of the edge of the screen. Alterantively, the rubber support strip might be recessed to accommodate the rib in addition to any tie bar extension and/ or ferrule.

Figure 4 illustrates a modification in which the rib 15 not only extends beyond the edge of the screen, but is joined, e.g. welded or forged, to the ferrule for extra strength, the rubber support strip 16 being suitably recessed. In this case the end of the rib is stepped to allow for the difference in diameter of the loops and ferrule.

It will be appreciated that such stepping could permit the rib to be secured directly to the tie bar so dispensing with the ferrule.

Furthermore the rib may be secured to any intermediate reinforcement strips, often provided parallel to the strips and located on the tie bars, and the ribs may serve directly as, or carry, a superstructure e.g.

for a rapping device.

Advantages of a rib secured to the loops as hereinbefore described are that, firstly, the loops are secured firmly together at a position remote from the upper screen surface, so giving a beam-like construction with consequent improved bending moment, which can be improved still further by increasing the depth of the rib or varying its cross-section to give a greater cross-sectional area at a position as far below the screen surface as possible e.g. an inverted T or bottom bead. If the loops were merely welded together say with a weld run across their lower portions, when the plate was flattened again the welds be weakened and liable to fracture in service. The ribs, on the other hand, will, themselves bend and thus reduce any tendency to weld fracture.

WHAT WE CLAIM IS: 1. An apertured panel comprising a plurality of wire members having loops at intervals along their lengths and spaced so as to define slit apertures between adjacent wires, the wires being connected together as a panel by tie rods, tubes or the like extending through aligned loops thereof, outer parts of at least some of said aligned loops being secured to a rib member or members extending externally thereof and transversely to the wires.

2. An apertured panel as claimed in claim 1, wherein the spacing between wires is determined by cooperating loop portion configurations.

3. An apertured panel as claimed in claim 1 or 2, wherein upper wider parts of the loop portions of adjacent wire members are in contact.

4. An apertured panel as claimed in claim 1, 2 or 3, wherein the rib member is welded to said loop parts.

5. An apertured panel as claimed in claim 1, 2 or 3, wherein the rib member is compounded with the said loop parts with complementary deformation of mating parts thereof.

6. An apertured panel as claimed in any preceding claim, wherein loop parts of at least some of the wires are secured to the tie rod, tube or the like extending therethrough.

7. An apertured panel as claimed in claim 6, wherein the loop parts are secured to the tie rod, tube or the like by welding or compounding.

8. An apertured panel as claimed in any preceding claim, wherein the or each rib member extends at least to an edge of the panel.

9. An apertured panel as claimed in claim 8, wherein an end portion of a rib member extends beyond the edge of the panel and is secured to an end portion of the tie rod, tube or the like extending through the loop parts to which the rib member is secured.

10. An apertured panel as claimed in claim 9, wherein the rib member end portion is secured directly to the end portion of the tie rod, tube or the like.

11. An apertured panel as claimed in claim 9, wherein the rib member end portion is secured to a sleeve or ferrule which is itself secured to the end portion of the tie rod, tube or the like.

12. An apertured panel as claimed in any preceding claim, wherein the rib member is of rectangular section of depth substantially greater than width.

13. An apertured panel for use in screening substantially as described herein with reference to and as shown in the accompanying drawings.

14. A method of making an apertured panel as claimed in claim 1, comprising assembling a plurality of wires having loops at intervals along their lengths onto tie rods, tubes or the like extending through aligned loops such that the parts of the wires between the loops are spaced to define desired slit apertures, aligning a rib member with the loops and securing mating portions of the rib member and loops together by application of mutual pressure and/or heat.

15. A method as claimed in claim 14, wherein the heat and/or pressure is sufficient to forge the mating portions together.

16. A method as claimed in claim 14, wherein the heat and/or pressure is sufficient to weld the mating portions together.

17. A method as claimed in claim 14, 15 or 16, including connecting the wires and rib member to opposite electrodes of electrical resistance heating apparatus so that when the rib member and loops are brought together current flows between them to generate the required heat.

18. A method as claimed in claim 14, 15 or 16, wherein the loops are simultaneously secured to the rib member and interiorly to the tie rod, tube or the like.

19. A method as claimed in claim 18, wherein the tie rod, tube or the like and rib member are connected to opposite elec

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. position remote from the upper screen surface, so giving a beam-like construction with consequent improved bending moment, which can be improved still further by increasing the depth of the rib or varying its cross-section to give a greater cross-sectional area at a position as far below the screen surface as possible e.g. an inverted T or bottom bead. If the loops were merely welded together say with a weld run across their lower portions, when the plate was flattened again the welds be weakened and liable to fracture in service. The ribs, on the other hand, will, themselves bend and thus reduce any tendency to weld fracture. WHAT WE CLAIM IS:

1. An apertured panel comprising a plurality of wire members having loops at intervals along their lengths and spaced so as to define slit apertures between adjacent wires, the wires being connected together as a panel by tie rods, tubes or the like extending through aligned loops thereof, outer parts of at least some of said aligned loops being secured to a rib member or members extending externally thereof and transversely to the wires.

trodes of electrical resistance heating apparatus so that when the rib member is brought into contact with the loops current flows through tie rod, tube or the like, the loops and the rib member to generate the required heat.

20. A method of making an apertured panel as claimed in claim 14 and substantially as described herein.