GB2172572A - Improvements in or relating to apparatus for carrying glass sheets - Google Patents

Abstract

Apparatus for carrying a pack of vertical glass sheets has upper holding arms (72) movable away from and towards lower support feet (62) so that the pack can be located and held between them. Flexible wires (202) attached to the upper holding arms (72) can be secured by releasable clamps (203, 204, 205) to prevent upward movement of the arms, which might release the pack, but to permit downward movement of the arms so as to accommodate bowing of the pack. <IMAGE>

Description

SPECIFICATION Improvements in or relating to apparatus for car- rying glass sheets This invention concerns improvements in or relating to apparatus for carrying glass sheets and relates more particularly to apparatus for carrying a pack of glass sheets in substantially vertical disposition, i.e. with the faces of adjacent sheets substantially vertical and in contact with one another.

Such apparatus, sometimes referred to as a 'grab', is used for example to transport packs of glass to and from storage locations in a warehouse. The apparatus commonly comprises lower support means, usually in the form of a pair of feet, on which the bottom edges of the sheets rest, and upper holding means, usually in the form of a pair of arms, which engage over the top edges of the sheets and behind the top of the back sheet.

The upper holding means or arms are normally freely slidable along substantially vertical bars, so that they can be moved in a direction away from the lower support means, i.e. raised, to permit loading of a pack onto the lower support means, and then moved towards the lower support means, i.e. lowered, to engage over the top of the pack and hold it in place, the upper holding means or arms being urged downwardly by gravity under their own weight. The apparatus or grab can then be moved, for example by a crane hoist, to transport the pack of glass held thereon to a desired location for unloading where the upper support means are again raised to release the glass for removal. An example of such apparatus is disclosed in European Patent Application No. 82305497.8 Publication Number 0080264.

It will be understood that safe holding of the glass on the apparatus or grab during transport of the pack is highly important, not only because of risk of glass wastage through breakage, but also because glass falling from the apparatus or grab represents a real hazard to personnel and equipment in the vicinity. Such risks can be aggravated by the presence of one or more breaking or broken sheets in the pack, and falling of a complete pack must be viewed as a very serious mishap.

According to the present invention there is provided apparatus for carrying a packof glass sheets in substantially vertical disposition having lower support means for the bottom of the pack and upper holding means for the top of the pack, the upper holding means being movable away from and towards the lower support means to enable the pack to be located and held between them, characterised by releasable securing means for the upper holding means which prevent upward movement of the upper holding means away from the top of a held pack but permit downward movement of the upper holding means towards the lower support means.

The provision of such securing means, which can be released as a pack is being loaded on or unloaded from the apparatus, can improve the safe carrying of the glass. It has been found that if a sheet of glass in the pack is broken or breaks, e.g.

along a central generally vertical vent, the parts of the broken sheet can tend to fall outwardly in a manner such that their upper edges urge the upper holding means upwardly. If these means are forced to move upwardly to an extent such that they no longer hold the top of the pack, the whole load can fall with consequential glass wastage and danger to personnel and equipment as mentioned previously. By preventing movement of the upper holding means when the pack is held its loss through this cause can be avoided. However, if the upper holding means is totally prevented from movement when the pack is held, it has been found that the sheets of glass in the pack can bow, particularly when relatively large sheets of thin glass are involved.Such bowing effectively lessens the height of the pack so that the top of some or all of the sheets may slip from the hold of the fixed upper holding means and fall, again with the consequence of glass wastage and danger. By providing, in accordance with the present invention, securing means which, when a pack is held, prevent upward, but still permit downward, movement of the upper holding means relative to the'lower support means, the upper holding means are stopped from being forced upwardly so as to release the top of the pack but are still able to move downwardly to retain a hold on the top of the pack if it distorts through bowing.

The releasable securing means preferably comprise a flexible tie element, such as a stranded wire, and releasable means, such as a clamp, for example having a cam lever, for securing the tie element. Where the upper holding means comprises a plurality of holding members, for example two holding arms, there may be provided a separate releasable securing means for each holding member.

In order that the invention may be better understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a grab apparatus, and Figure 2 is a detail of part of the apparatus of Figure 1 drawn to a different scale.

The basic apparatus shown in the drawing is essentially the same as that shown in Figure 8 of the above mentioned European Patent Application Publication Number 0080264 and is fully described in that specification, the relevant teachings of which are incorporated herein by reference. For present purposes it is sufficient to note that it has (using the same reference numerals as in that European Application) a pair of feet 62 providing lower support means, a pair of parallel substantially vertical bars 70 extending between horizontal cross pieces 66 and 68, and a pair of upper holding members in the form of substantially horizontal arms 72 having respective depending plates 76 at their ends remote from the bars 70, the arms 72 being mounted on respective collars 74 which are basically freely slidable under gravity along the bars 70.

In accordance with the present invention, however, releasable securing means are provided in association with the upper holding means constituted by the arms 72 which can prevent their upward movement but still permit their downward movement along the bars 70. Specifically, each of the collars 74 has connected thereto by means of a ferrule 201 a flexible tie element in the form of a stranded wire 202. This wire passes through releasable means in the form of a clamp comprising a box 203 housing a cam 204 with a bent handled lever 205 and mounted on the cross piece 68. The cam lever arrangement is shown in detail in Figure 2 and is anguiarly movable on a shaft 209 about an axis 0 to alter the spacing between a suitably shaped cam surface 206 and a guide surface 207 in the box.Thus, by moving the lever 205 downwardly from its position shown in Figure 2 the gap between the cam and guide surfaces 206 and 207 is reduced to an extent such that the wire 202 is firmly gripped between these surfaces. With the wire thus securely clamped, the collar 74 to which it is connected is prevented from moving upwardly, i.e. in a direction away from the support feet 62, beyond the position permitted by the length of wire between the collar and the clamp.

The collar 74 can, however, still move downwardly, i.e. in a direction towards the support feet 62, from that position, the wire between the collar and the clamp then flexing as necessary. To release the clamped wire, the lever 205 is moved upwardly back to the position shown in Figure 2 thereby opening up the gap between the surfaces 206 and 207 sufficiently to permit substantially free passage of the wire. At the free end of the wire there is a cap 208 to prevent fraying and to prevent inadvertent removal of the wire from the passage between surfaces 206 and 207.

Operation of the arrangement is briefly-as follows. To load a pack of glass sheets onto the apparatus, the wires 202 are released, i.e. unclamped, and the collars 74 are moved upwardly and held at or towards the top of the bars 70 so that the arms 72 are well clear of the level of the top of the pack.

The apparatus is then moved to position the feet 62 beneath the pack on a suitable raised support and is then lifted sufficiently to bring the feet 62 into engagement with the bottom edges of the substantially vertical sheets in the pack. The collars 74 are then lowered along the bars 70 to a position at which the arms 72 engage the top edges of the sheets and the plates 76 engage behind the top of the back sheet in the pack. During such downward movement of the collars 74 the wires 202 run through the respective opened passages between the clamping surfaces 206 and 207 so that, when the collars are at the position where the arms 72 are against the top of the pack, the length of wire between the clamp and the collar is correct for preventing upward movement of the collar from that position. The levers 205 are then turned by an operator to clamp the wires.The pack is now held between the feet 62 and the arms 72 with the latter secured against upward movement from their holding position but able to move downwardly if needs be. The apparatus can then be hoisted to transport the pack to a required location. If a sheet in the pack should break or be broken it cannot force the arms 72 upwardly with the consequential risks because the collars 74 are tied to prevent it.

However, if the pack should distort by bowing of the sheets so that their top edges move downwardly, the collars 74 can move downwardly also under gravity and the arms 72 will maintain en gagement with the top edges of the sheets and so retain a hold on the top of the pack. When the ap paratus is at the required unloading location it is lowered to deposit the pack on a suitable raised support, the levers 205 are operated to unclamp the wires 202 and the collars 74 are moved upwardly along the bars 70 to take and hold the arms 72 well clear of the top of the pack. During this upward movement of the collars 74 the released wires 202 run through the respective passages in the clamping boxes 203. The apparatus can then be lowered slightly to clear the feet 62 from the bottom of the pack, and then withdrawn.

It will be appreciated that, with the collars 74 slidable along the bars 70, any height of pack within the possible range of movement of the arms 72 can be accommodated and secured since the collars 74 can occupy any position along the bars 70 and the wires 202 can be clamped with the collars at any such position to prevent their upward movement therefrom.

It will further be appreciated that the particular embodiment of apparatus or grab shown and specifically described is given by way of illustration and example and the invention is applicable to other forms of apparatus or grabs having lower support means and movable upper holding means for carrying a pack of glass sheets. It will also be appreciated that, while the described form of securing means is a preferred arrangement, other forms may be devised within the scope of the invention.

Claims (8)

1. Apparatus for carrying a pack of glass sheets in substantially vertical disposition having lower support means for the bottom of the pack and upper holding means for the top of the pack, the upper holding means being movable away from and towards the lower support means to enable the pack to be located and held between them, characterised by releasable securing means for the upper holding means which prevent upward movement of the upper holding means away from the top of a held pack but permit downward movement of the upper holding means towards the lower support means.

2. Apparatus according to Claim 1 in which the releasable securing means comprise a flexible tie element and releasable means for securing the tie element.

3. Apparatus according to Claim 2 in which the flexible tie element is a stranded wire.

4. Apparatus according to Claim 2 or Claim 3 in which the releasable means is a clamp.

5. Apparatus according to Claim 4 in which the clamp has a cam lever.

6. Apparatus according to any preceding claim in which the upper holding means comprises a plurality of holding members and having a separate releasable securing means for each holding member.

7. Apparatus according to Claim 6 comprising two upper holding members.

8. Apparatus for carrying glass sheets substantially as described herein with reference to the accompanying drawings.