GB2235140A

GB2235140A - Parallel-wire screen

Info

Publication number: GB2235140A
Application number: GB9018008A
Authority: GB
Inventors: Frank Mcmahon
Original assignee: Powerscreen International Distribution Ltd
Current assignee: Powerscreen International Distribution Ltd
Priority date: 1989-08-23
Filing date: 1990-08-16
Publication date: 1991-02-27
Anticipated expiration: 2010-08-16
Also published as: GB2235140B; GB8919204D0; GB9018008D0

Abstract

A screening has a series of parallel wires (10) extending across a top opening between two longitudinally opposed ends of a box frame having one or more transverse support bars (18). A support bar capping member (20) is provided for the or each support bar (18). The capping member (20) is of inverted 'U' cross-section and has wire support means formed of a series, equal in number to the series of parallel wires (10), of transverse cuts (22) through the web (24) and impinging into the limbs (26) each cut (22) being to receive a wire (10). Two straps (28) are provided to be located along the inside of the web (24) with a respective wire (10) to be trapped therebetween. One or more capping members (20) can be pre-fitted to a quick-fit screen. <IMAGE>

Description

SCREENING APPARATUS.

This invention relates to screening apparatus of the type having a box frame open at the top and at the bottom, and particularly relates to replacable parallel wire screens to be secured across, and mask the opening of, the top of the box frame. Such screening apparatus is normally, but not necessarily, mountable on an outer second frame and connected thereto through vibration dampening elements, the box frame being adapted through vibratory, reciprocatory or oscillatory means to move and thereby sift discrete material placed on top of the screen thereby to size-classify the material into different grades. A disadvantage of parallel wire screens for such screening apparatus is that the wires wear out through use due mainly to the impact of the material onto the screen.To overcome the time delay involved in replacement screens being fitted, quick clamp replacable screens have been proposed. Such quick clamp screens comprise two spaced clamping brackets to be mounted one at each end of longitudinally opposed ends of a screen box frame and between which brackets a series of parallel wires are secured. Two or more support bars, which can be removable, extend transversely of the top opening of the box frame and wire spacer means are provided longitudinally along the top face of each bar to hold the wires in a determined parallel spaced relationship.While such quick fit screens have been beneficial in time saved ie. less time involved in the screening apparatus being out of commission, a further disadvantage has been discovered, namely with movement of the wires, on impact of material thereon, relative to the bars (they are of metal and/or are each provided with a metal capping member), the wires are wearing quicker than hitherto.

It is an object of the present invention to obviate or mitigate this latter disadvantage.

Accordingly, one aspect of the present invention is in or for a screening apparatus of the type stated having'a series of parallel wires extending across a top opening between two opposed ends of a box frame having one or more transverse support bars, a support bar capping member for the or each support bar, the capping member being of inverted 'U' cross-section and having wire support means formed of a series, equal in number to the series of parallel wires, of transverse cuts through the web and impinging into the limbs, each cut being to receive a wire, and two straps being provided to be located along the inside of the web with a respective wire to be trapped therebetween.

Also accordingly, a second aspect of the present invention is a quick-fit screen for fitting over a top opening of a box frame, having one or more transverse support bars, of a screening apparatus of the type stated, the screen comprising two clamping brackets securable to two opposed ends of the box frame with a series of parallel wires therebetween, characterised in that one or more support bar capping members is provided for fitment over the or each support bar provided on the box frame, each capping member being of inverted 'U' cross-section and having wire spacer means formed by a series, equal in number to the series of parallel wires, of transverse cuts through the web and impinging into the limbs, each cut being to receive a wire, and two straps being provided to be located along the inside of the web with a respective wire trapped therebetween.

Preferably, the straps are of aluminium, but may be of hard wearing plastics material.

Preferably also, locating means are provided in the inside faces of the limbs of the member to hold the web remote strap in place.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a screening apparatus according to the present invention; Fig. 2 is a cross-sectional view of the apparatus along the line II-II of Fig. 1 to a larger scale; and Fig. 3 is a detailed perspective view of one end of a support bar having a capping member thereon with parallel wires engaged therewith.

Referring to the drawings, a screening apparatus of the type stated has a series of parallel wires 10 extending across a top opening between two longitudinally opposed ends 12, 14 of a box frame 16 having three transverse support bars 18. A support bar capping member 20 for each support bar 18 is provided with the capping member 20 being of metal and of inverted 'U' cross-section as shown. Wire spacer means formed of a series, equal in number to the series of parallel wires 10, of transverse cuts 22 are made through the web 24 and impinging into the limbs 26. Each cut 22 is to receive a wire 10. Two straps 28 are provided to be located along the inside of the web 24 as shown with a respective wire 10 trapped therebetween.

The straps 28 are of aluminium, but may be of hard wearing plastics material.

A support bar capping member 20 can be fitted over each existing support bar 18 when the worn wires are being replaced, or alternatively one or more capping members 20 can be pre-fitted to a quick-fit screen for fitting over the top opening of a box frame 16 having one or more transverse support bars 18 (three shown in Figs. 1 and 2) of a screening apparatus. The screen as shown comprises two clamping brackets 30 securable to two opposed ends 12, 14 of the box frame 16 with a series of parallel wires 10 therebetween. Three support bar capping members 20 are provided for fitment, one over each support bar 18 provided on the box frame 16.

Each capping member 20 is held onto the quick-fit screen by the wires 10 being trapped between the two straps 28.

Locating means (not shown), such as inwardlydirected ribs, flanges or a series of inwardly-directed protrusions, are provided in the inside faces of the limbs 26 of the member 20 to hold the web remote strap 28 in place.

The capping members 20 can slide along the wires 10 and therefore can be positioned over the support bars 18 whatever the distance is between adjacent bars 18.

Also, the capping members can be slide, when not in use, against one of the clamping brackets to facilitate ease of packing, transporting and storage.

For fitment of a quick-fit screen, the existing screen is removed and the new screen is laid over the top opening of the box frame 16. One clamping bracket 30 is placed around a clamping member 32 and the individual capping members 20 are fitted over respective support bars 18. The other clamping bracket 30 is then placed around a second clamping member 32 and the two clamping members 32 are moved relatively apart to tension the wires 10.

Claims

CLAIMS:

1. In or for a screening apparatus of the type stated having a series of parallel wires extending across a top opening between two opposed ends of a box frame having one or more transverse support bars, a support bar capping member for the or each support bar, the capping member being of inverted 'U' cross-section and having wire support means formed of a series, equal in number to the series of parallel wires, of transverse cuts through the web and impinging into the limbs, each cut being to receive a wire, and two straps being provided to be located along the inside of the web with a respective wire to be trapped therebetween.

2. In or for a screening apparatus of the type stated, a quick-fit screen for fitting over a top opening of a box frame, having one or more transverse support bars, the screen comprising two clamping brackets securable to two opposed ends of the box frame with a series of parallel wires therebetween, characterised in that one or more support bar capping members is provided for fitment over the or each support bar provided on the box frame, each capping member being of inverted 'U' cross-section and having wire spacer means formed by a series, equal in number to the series of parallel wires, of transverse cuts through the web and impinging into the limbs, each cut being to receive a wire, and two straps being provided to be located along the inside of the web with a respective wire trapped therebetween.

3. A support bar capping member as claimed in Claim 1 or 2, wherein the straps are of aluminium.

4. A support bar capping member as claimed in Claim 1 or 2, wherein the straps are of hard wearing plastics material.

5. A support bar capping member as claimed in any one of Claims 1, 2, 3 or 4, wherein locating means are provided in the inside faces of the limbs of the member to hold the web remote strap in place.

6. A support bar capping member substantially as hereinbefore described with reference to the accompanying drawings.

7. A quick-fit screen substantially as hereinbefore described with reference to the accompanying drawings.