Apparatus For Transferring Sheet Material

Abstract

Apparatus for transferring glass sheets comprises a sequence of drive rollers above the transfer path and suction means arranged to draw the sheets against the rollers so that the sheets are advanced by the rollers. In order to release a sheet onto a stack, when the sheet has reached a predetermined position along the path, suction release means may be provided or mechanical means may be provided to force the sheet away from the rollers.

Description

BACKGROUND OF THE INVENTION

This invention relates to the transferring of sheet material, for example glass sheets from a first location to a second location. More especially the invention relates to the stacking of sheets which are being fed in succession along a conveyor to a stacking station, or to the unstacking of a stack of sheets one-by-one and transferring those sheets to a conveyor by which they are transferred to a further treatment.

It is a main object of the present invention to provide an improved apparatus and method for transferring sheet material by a suction arrangement in which sheets are lifted and conveyed by suction applied to the upper surface of the sheets. The invention also relates to means for releasing the suction when required to lower a sheet onto a stack of sheets.

SUMMARY

The invention provides an advance in the automatic transfer of glass sheets from one location to another. A succession of drive members are arranged above the transfer path and suction means is provided above the transfer path and arranged to operate so that suction is applied between the drive members to draw the sheets against the drive members. In this way the sheets are advanced by the drive members while suctionally held against the lower surfaces of the drive members. This enables improved selective stacking of the sheets when the transfer path passes over one or more stacking stations. If a sheet is to be stacked, means is provided to release the sheet from the drive members when in a required position so that the sheet falls onto the stack. The means for releasing the sheet may comprise means for terminating the suction effect adjacent the drive members holding the sheet. Alternatively a mechanical device may be provided to force the sheet away from the drive members.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation of one embodiment of apparatus according to the invention for transferring glass sheets from a first conveyor to a second conveyor,

FIG. 2 is a front elevation of the apparatus of FIG. 1,

FIG. 3 is an underneath view of the suction arrangements of the apparatus of FIGS. 1 and 2,

FIG. 4 is a view similar to FIG. 3 of a modification of the apparatus of FIGS. 1 to 3,

FIG. 5 is a side elevation partly in section of another embodiment according to the invention of apparatus for transferring glass sheets from one conveyor to a second conveyor,

FIG. 6 is a front elevation of the apparatus of FIG. 5,

FIG. 7 is a sectional side elevation of yet another apparatus according to the invention for transferring glass sheets,

FIG. 8 is a side elevation partly in section of yet another apparatus according to the invention for transferring glass sheets,

FIG. 9 illustrates the application of one embodiment of suction apparatus according to the invention for transferring glass sheets to a stacking location,

FIG. 10 is a plan view of the apparatus of FIG. 9,

FIG. 11 is a view similar to FIG. 9 of yet another apparatus for transferring glass sheets to a stacking station,

FIG. 12 is a side elevation showing another embodiment of the invention as applied to the selective stacking of sheets at a plurality of stacking stations,

FIG. 13 is a side elevation of part of another embodiment of the invention which may be used with a stacking arrangement of the type shown in FIG. 12,

FIG. 14 is a half plan view of the part of the embodiment shown in FIG. 13,

FIG. 15 is a diagrammatic view of control apparatus used with the embodiment shown in FIGS. 13 and 14,

FIG. 16 is a side elevation of another embodiment of the invention for use in stacking glass sheets,

FIG. 17 is a side elevation of yet another embodiment of the invention for use in stacking glass sheets,

FIG. 18 is a perspective view of part of the apparatus shown in FIG. 17, and

FIG. 19 shows an alternative construction for part of the apparatus shown in FIG. 17.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawings like references indicate the same or similar parts.

Referring to FIGS. 1 and 2 of the drawings there is shown a conveyor for glass sheets comprising a series of rotatable rollers which are driven in known manner and by known means to feed glass sheets supported thereon horizontally to a transfer station generally indicated at 2. The last rollers 1 constitute a first location from which glass sheets are to be transferred to a second location constituted by the first rollers indicated at 14 of a further conveyor. The conveyor rollers 1 and 14 are carried by a common bed 13. The rollers 14 are also driven so as to convey a sheet when transferred to those rollers rapidly away from the transfer station. A vertically adjustable stacking table or the like may be located below the transfer station 2 so that glass sheets may, when desired, be transferred from the conveyor rollers 1 to the stack or taken from the stack and transferred to the conveyor rollers 14.

At the transfer station there is mounted a series of driven horizontal rollers 3 which are mounted in bearings depending from a bracket 4 so that the lower faces of the rollers 3 are spaced along and above the path of travel of the glass sheets. All the rollers 1, 3 and 14 may be of known form, being generally cylindrical with spaced projecting rings of a suitable material for example rubber which engage the glass sheets being fed. The peripheries of the rollers which contact the glass sheets are thus the peripheries of the projecting rings. The rollers may be of plain cylindrical form however.

At the transfer station in the space between each pair of successive driven rollers 3 is a suction chamber 5 the lower end of which is shaped as shown in FIG. 1 to fit closely to but not to be in contact with the periphery of the rollers 3. The lower end of each suction chamber has spread hood-like form as shown in FIG. 2. Each suction chamber has a bottom wall formed by horizontal plates 6, shown in FIG. 3 having holes 7. The bottom surface of each plate is at a level slightly above, for example 1.2 mms. above the level of the lowermost point of the peripheries of the rollers 3. The suction chambers 5 communicate through respective ducts 8 to a common suction manifold connected by a duct 10 to a fan unit, not shown.

The rollers 3 are driven to rotate in any convenient manner. For example there may be a chain drive connection between the rollers 3, the rollers carrying suitable sprockets 11, FIG. 2, to provide the common drive connection while one of the rollers has a projecting drive shaft carrying a drive gear 12. The bracket 4 is supported from the bed 13 by support struts which have been omitted for the sake of clarity.

Glass sheets are fed in spaced succession on the driven roller conveyor 1 to the transfer station. Suction applied to the suction chambers 5 causes a glass sheet S as it travels beneath the rollers 3 at the first location constituted by the end rollers 1 of the driven conveyor, to be suctionally held with its upper face in engagement with the peripheries of the rollers 3. The presence of the sheet near the bottom faces of the suction chambers provides a restriction to air flow offered by the restricted gaps between the glass sheet and the bottom of the first suction chamber, so that a reduced pressure is created over the sheet causing the sheet to be lifted onto the first roller and thereafter to be held against the rollers 3 which are driven to transfer that sheet to be deposited on the rollers 14 at the second location as the sheet moves beyond the effective range of the applied suction and falls under gravity onto the surfaces of the rollers 14. Alternatively, when the sheet is immediately below the transfer station, the suction may be temporarily stopped to release the sheet onto a stacking table.

The height of the lower surfaces of the rollers 3 above the level of the rollers 1 is dependent on the application to which the apparatus is to be put. If the apparatus is required merely to transfer glass sheets of one set thickness the difference in level between the uppermost points of the peripheries of the rollers 1 and the lowermost points of the peripheries of the rollers 3 is theoretically only the sheet thickness but in practice slightly greater than the sheet thickness. If the apparatus is to transfer sheets of different thicknesses without adjusting the level of the rollers 3 for each thickness then the difference in level is slightly greater than the thickness of the thickest sheets which are to be transferred. If the apparatus is to effect a predetermined lift of the sheet it transfers for example to carry it over an obstacle then the difference in level is set accordingly.

Where the difference in level is not excessive the suction applied to the glass sheet is normally sufficient to effect the initial lifting of the sheet into engagement with the driven rollers 3. If the level difference is too great however to permit the suction to effect the initial lifting, means may be provided for initially lifting the sheet into effective range of suction action, that is sufficiently close to the lower surfaces of the suction chamber to provide the necessary reduced pressure to draw the sheet into engagement with the rollers 3. For example the downstream roller or rollers of the conveyor 1 may be mounted for vertical movement to lift a sheet supported thereon into the ambience of the suction at the transfer station as the leading edge of the sheet moves beneath the first of the suction chambers.

The disengagement of the sheet from the rollers 3 may be effected solely by gravity as the sheet moves out of the effective range of the applied suction and falls under its own weight for example onto the rollers 14. Alternatively the deposition of the sheet may be assisted mechanically for example by means of a roller or rollers mounted at the end of the transfer station adjacent the second position slightly below the level of the rollers 3 so that it prises the sheet away from the suction action and removes the restriction to air flow thus breaking the suction action. Such a downstream roller or rollers may be fixed to the bracket 4 slightly below the level of the rollers 3 or may be mounted on a subsidiary frame which can be moved vertically relative to the brackets 4 to lower those rollers thereby prising the sheet away from the rollers 3. The movement of such a subsidiary frame may be actuated by a limit switch tripped by a leading edge, or released by the clearing edge of the sheet being transferred as it moves beyond the downstream end of the transfer station. Alternatively the suction may be cut off from at least the downstream suction chamber or chambers when the sheet is beneath those chambers. This cutting off of the suction can be controlled for example by a limit switch actuated by the travelling sheet and operative to open the chamber or chambers to atmosphere. In another method of operation the deposition of a sheet may be pneumatically assisted by a suitably placed air blowing nozzle or nozzles or even by reversing the air flow through at least the downstream chamber or chambers 5 so that air is blown through the bottom of those chambers to break the suction and thereby permit the sheet to fall. This air flow from these chambers would also assist in pushing the sheet downwardly onto the rollers 14 at the second location.

FIG. 4 illustrates a modified form of base plate for the suction chambers. Instead of being provided with equi-spaced holes 7, the base plate of each chamber is formed with a slot 15 extending parallel to the rollers 3. FIG. 4 also illustrates additional rollers 16 mounted within the suction chambers 5 with their peripheries projecting slightly through the slots 15 so that the lowermost points of the peripheries of the rollers 16 are level with the lowermost points of the rollers 3. The additional rollers 16 are in some applications desirable to assist in preventing contact between the upper surface of a glass sheet being transferred and the suction chamber 5, particularly when the sheets are relatively thin and therefore flexible. The rollers 16 are driven from the same drive as the rollers 3 or may be idler rollers. When these rollers 16 are idler rollers a better drive of the glass sheet can usually be achieved if the rollers 16 are set with their lowermost points of their peripheries at a level very slightly above that of the lowermost points of the peripheries of the rollers 3.

FIGS. 5 and 6 show another embodiment of transfer apparatus according to the invention comprising a series of rollers 17 similar to the rollers 3 and mounted to be driven together in a series of suction chambers 18 of generally hood-like form. Each roller 17 is mounted in its own suction chamber at a level such that the peripheries of the rollers project slightly through openings 19 in the bases of these suction chambers. The suction chambers are separated in the hood from each other by partitions 18a and the projecting rings of the rollers project through the base openings of the suction chamber.

The rollers are driven by a suitable chain drive connecting round sprockets 20 on the roller shafts which sprockets are mounted outside the suction hood. One shaft carries a drive gear 21 for connection to an external drive.

The suction chambers 18 communicate with a common canopy 22 leading to a suction duct 23, and the roof of each of the individual suction chambers 18 is formed with a flow restrictor slot 24 of suitable value to prevent unduly high air flow when no glass sheet is present beneath the suction chambers. When a sheet is present the application of suction to the duct 23 creates a reduced pressure around the rollers 17 so that the sheet is suctionally held against those rollers and is moved forward thereby to the second location.

FIG. 7 shows another embodiment of transfer apparatus similar to that of FIGS. 5 and 6. The individual suction chambers are dispensed with and the driven rollers 17 are housed in a common suction hood 18b which forms the downward extension of a canopy 22 leading to the suction duct 23. In this embodiment the rollers 17 are plain cylindrical rollers and are closely spaced with the outer drive rollers adjacent the end walls of the suction hood. The restricted gap between adjacent rollers 17 and between the outer rollers and the end walls of the suction hood act to restrict air flow and thereby prevent undesirably high air flow when no sheet is present beneath the rollers 17. The gaps between the peripheries of adjacent rollers 17 and between those rollers and the end walls of the hood are of a size such that the restriction to air flow afforded thereby is of the same order as that afforded by the gap between the upper surface of a glass sheet being transferred and the lower edges of the walls of the suction hood 18. The rollers 17 may project from the bottom of the suction hood by a distance of about 1.2 mms. When a glass sheet is beneath a part of the hood and effectively bridges a space between adjacent rollers a reduced pressure is created in the space bounded by the rollers and the glass sheet and the sheet is suctionally held against the rollers 17.

FIG. 8 shows how the simplified apparatus of FIG. 7 may be modified to provide more individual suction connection to the spaces between adjacent rollers. An air flow restrictor plate 24 is provided having restrictor holes 24a formed so as to be positioned over the spaces between adjacent rollers and between the end rollers and the end walls of the hood 18. A plurality of flexible flaps 24b are provided mounted on and depending from the plate 24 so as to rest on the drive rollers 17. In this way the spaces between adjacent rollers 17 and between the upstream and downstream rollers and the adjacent end walls of the hood 18 are effectively isolated from each other. The flaps 24b are sufficiently stiff to prevent undue air flow between each flap and the roller on which it rests.

FIGS. 9 and 10 illustrate the stacking of sheets employing apparatus according to the invention. Glass sheets are conveyed along a roller conveyor 25 to a position beneath transfer apparatus according to the invention which is generally indicated at 26. This transfer apparatus has the construction illustrated in FIGS. 1 to 3. At the first location on the conveyor 25 beneath the transfer apparatus 26 glass sheets are sucked against the rollers 3 and are transferred thereby in a direction normal to their direction of travel on the conveyor 25 to a second location constituted as a stacking station generally indicated at 27.

At the stacking station 27 there is a receiving table 28 above which the end rollers 3 are mounted on a vertically movable frame 29 which may be moved by an actuating mechanism so that the rollers 3 on the frame 29 project below the level of the lowermost point of the peripheries of the other rollers 3. As a glass sheet is transferred in the direction of the arrow towards the stacking station its leading edge engages beneath the rollers on the frame 29 which mechanically prise it from the suction action of the transfer apparatus thus breaking the suction and permitting the sheet to fall towards the receiving table. A fixed stop 30 which has a rubber facing is positioned to be engaged by the leading edge of the sheet being deposited onto the table. This arrests the sheets momentum and to some extent ensures that the sheets are lined up in the stack on the stacking table. The driving connections for the rollers on the frame 29 are arranged to accommodate the vertical movement of the frame.

Instead of using rollers on the frame 29 other arrangements may be provided to break the suction. The sheets may be deposited by breaking the suction supply to the downstream suction chambers.

In operation glass sheets are fed in succession along the conveyor 25 to the first location beneath the transfer apparatus 26 where a limit switch 40 engaged by the leading edge of each sheet stops the drive to the conveyor 25. Suction is then applied to the transfer apparatus 26 so that the sheet is lifted and suctionally held in engagement with the rollers 3 which are then driven to transfer the sheet to the second location at the stacking station. The sheets fall in turn onto the receiving table 28 and as each sheet is deposited the conveyor 25 is restarted to bring the next beneath the suction transfer apparatus. As each sheet falls onto the receiving table, the table is lowered in known stepwise manner by the thickness of one sheet at a time so that each sheet deposited from the transfer apparatus falls only a short distance and a stack of sheets is gradually built up on the table. When a stack is complete it is removed from the table for packing or warehousing and the table is raised to its uppermost position for the formation of a further stack. In addition to the stop 30 other devices for example air jets may be provided to align successive sheets correctly as they are formed into a stack and if desired a separating material for example wood flour may be blown onto the surface of each sheet as it is stacked so as to avoid abrasive friction between successive sheets. The conveyor 25 may feed single sheets in succession or may feed batches of sheets placed side-by-side on the conveyor, each batch comprising a plurality of sheets. In this case the transfer apparatus simultaneously picks up all the sheets of a batch and transfers those sheets in succession to the stacking station.

FIG. 11 illustrates a stacking arrangement in which the conveyor 25 is in line with the transfer apparatus and the stacking station. With this arrangement the conveyor 25 is continuously operable and suction is continuously applied to the transfer apparatus which is arranged so that its rollers 3 feed the sheets forwardly at the same speed as the speed of the sheets on the conveyor 25.

FIG. 12 illustrates a selective stacking arrangement in which the transfer apparatus 26 extends over a plurality of stacking stations indicated at 31, 32 and 33 at which the sheets are selectively deposited on a size basis. Each station has a detecting device 34 which detects the size of a sheet being fed by the transfer apparatus 26 by engagement of the leading and trailing edges of the sheet. Each detecting device is connected to a control station whose output is connected to means for operating a vertically movable frame 35 carrying the end rollers 3 above each station so that those rollers are movable from a raised position in line with the rest of the transfer rollers 3 to a depressed position below the level of the lowermost points of the peripheries of the other transfer rollers 3. When a detector device 34 detects that the sheet being transferred is of a size destined for its associated stacking station the control means to which it is connected depresses the associated frame 35 so that the sheet is prised from the suction over the stacking station and deposited at that station.

Other arrangements as previously described may be utilised for depositing a sheet at the appropriate stacking station.

This station selective deposition of sheets may be automatically controlled or may be controlled by an operator from a control panel. One of the stacking stations may be reserved for faulty or damaged sheets and automatic inspecting means may be embodied in the transfer apparatus to detect such sheets and to control the apparatus so that such sheets are deposited at the reserve station.

It is usual to deposit the sheets at appropriate stations on a size selective basis. There are preferably at least two stacking stations for each sheet size so that the sheets of a given size can continue to be fed to one station shile a stack of sheets of that size is being removed from the other station.

The transfer apparatus 26 in FIGS. 9 and 10 may take any of the forms illustrated in FIGS. 1 to 3 or FIGS. 1, 2 and 4 or FIGS. 5 and 6 or FIG. 7 or FIG. 8.

In the drawings FIGS. 9, 10, 11 and 12 show mechanical arrangements for breaking the suction to release a sheet. However, FIGS. 13, 14 and 15 show a preferred arrangement in which the deposit of a glass sheet is effected by controlling the suction applied to the sheet. FIG. 13 shows part of a transfer apparatus for use in a selective stacking arrangement of the type shown in FIG. 12 in which a plurality of stacking stations are provided. The part of the apparatus shown in FIG. 13 is for use above one of the stacking stations, similar transfer apparatus being provided above each of the other stacking stations. In use a succession of glass sheets are moved in the direction of the arrow by the driven transfer rollers 3. The sheets are held against the lower peripheries of the rollers 3 by suction. The rollers 3 are mounted within a suction chamber having a roof 50. Openings 51 and 52 are provided in the roof above the rollers and suction is applied to the openings from a hood (not shown) similar to that used in FIGS. 7 and 8. The rollers 3 are closely spaced so that the gaps between the rollers provide restrictions to the flow of air when there is no glass sheet below the rollers. Mounted on the underside of the roof 50 are a number of flaps 53 pivotally mounted on shafts 49 which may be selectively rotated and held in position by spring plungers 54 (FIG. 14) so that one flap is lowered, as indicated at 53a, to lie closely adjacent the roller beneath it and thereby effectively seal off a portion of the suction chamber between the flap 53a and a fixed sealing flap 54 located at the end of the suction chamber closely above one of the rollers 3. The flap 53 which is lowered is selected in accordance with the length of glass being used so that the distance between the flaps 54 and 53a is approximately equal to one sheet length. As a glass sheet travels beneath the rollers 3 it is held against the rollers by suction which exists on both sides of the flap 53a due to the two openings 51 and 52. As the sheet moves forward, its leading edge trips a limit switch 55 (FIG. 15) which actuates a pneumatic cylinder controlling a rotatable damper 56 located in the opening 51. The damper 56 moves so as to cut off the application of suction through the opening 51 and air then flows past the sheet and between the rollers 3 to release the vacuum in the portion of the suction chamber between the flaps 53a and 54. The limit switch 55 is positioned so that the vacuum is released when the sheet lies immediately below the portion of the suction chamber between the flaps 53a and 54. In this way successive sheets may be dropped accurately in position onto a stacking table or trolley 57 so as to form a stack of sheets 58 with the leading edges of the sheets against a stop 30 as indicated in FIG. 15.

When the vacuum between the flaps 53a and 54 is released the air flow into that part of the suction chamber is very rapid and has the effect of pushing the sheet downwardly. The purpose of splitting the suction chamber into two parts by lowering one of the flaps 53 is that when the suction is released in the part of the suction chamber to the left of the lowered flap, the suction is maintained in the chamber to the right of the lowered flap due to the opening 52. Consequently, while one sheet is being dropped onto the stack, other sheets to the right of the lowered flap are still held against the rollers by suction. If a sheet moving past the rollers is not required on that stack, the damper 56 is not moved to release the suction so that the sheet continues to be suctionally supported and moves on to a similar transfer apparatus above the next stacking station.

As is shown in the plan view of FIG. 14, the apparatus includes a number of horizontal channels arranged side by side in one integral unit, each channel being as shown in FIG. 13. FIG. 14 shows only half the width of the entire apparatus and this half includes four channels 60, 61, 62 and 63. Vertical partitions 64, 65 and 66 extend horizontally and provide separate suction chambers for the various channels. The dampers 56 for each channel are mounted on a common shaft and the shafts 49 for the pivoted flaps 53 extend across all the channels. In this way the position of the dampers 56 and flaps 53 is always the same in each channel. By subdividing the suction area into a number of separate narrow channels, different widths of glass sheet can be handled. The spacing between the partitions 64, 65 and 66 is one half the narrowest sheet width to be handled so that for all sheets used, at least half the sheet area is subject to the suction action.

FIG. 15 shows mechanical pushers 70 arranged to be moved by double acting pneumatic cylinders 71. The pushers 70 engage the rear edge of each sheet as it is dropped onto the stack 58 so as to overcome any bounce back from the fixed stop 30. The cylinders 71 are supplied by air pipes 72 connected to a four way solenoid valve 73. The solenoid valve 73 is connected to an air supply by pipes 74 via a filter 75, regulator 76 and lubricator 77. The limit switch 55 is connected to a control unit 78 connected to a D.C. electrical supply via terminals 79. The control unit 78 provides one output at terminals 80 for connection to a solenoid valve controlling the operation of the dampers 56 in dependance on the operation of the switch 55. A second delayed output is provided at terminals 81 connected to the solenoid valve 73 to control operation of the pneumatic cylinders 71.

The example shown in FIG. 16 is basically similar to that shown in FIG. 8. Each roller 3 in the hood, except the first roller 3a, has associated with it a flexible felt flap 80 engaging the periphery of the roller so as to provide a separate suction chamber with a separate suction aperture for each roller. The first roller 3a is a driven roller but it is narrow and is tyred. Above the roller 3a is an opening 81 providing very low restriction to air flow. In operation, as a glass sheet travels beneath the rollers in the direction of the arrow A, it bridges the gap between the first roller 3a and the next roller 3, and thereby provides a restriction to air flow so that suction is applied over all the rollers and the sheet is suctionally held thereto. When the trailing edge of the sheet travels past the first roller 3a and ceases to provide such restriction to air flow, the low restriction opening 81 permits a high air flow so as to reduce the vacuum over the other rollers and the glass sheet drops onto the stack 58. Size adjustment flaps 53 are provided for the same reason as previously described with reference to FIG. 13. Each flap 53 is housed in a separate chamber and when lowered block off a hole in the side wall of the chamber. In this way suction is not released for rollers supporting a sheet to the right of the lowered flap. An adjustable restrictor 82 is provided above the low restriction opening 81 so that the required air flow can be adjusted. A damper 56 is provided in the opening 81 so that when it is required that a sheet pass on without depositing on the stack 58, the damper 56 may be moved by a pneumatic cylinder to restrict the opening 81. The drop-off effect previously described will not then occur. FIG. 16 also shows air nozzles 83 for directing air between the top of the stack 58 and the next sheet dropping onto the stack.

FIG. 17 shows a further embodiment in which the suction is released by passage of the trailing edge of the sheet over the first roller in the suction chamber. The operation is generally similar to that described with reference to FIG. 16. In this case the damper is provided on the first roller 3b which is shown more clearly in FIG. 18. The roller 3b comprises two freely rotatable discs 85 and 86 with the valve damper plate 87 located between them. A pneumatic cylinder 88 and crank connection is provided to move the plate 87 between open and closed positions. An adjustable low restriction opening 90 is provided above the first roller 3b. With the damper 87 open, air flows past the plate 87 when the trailing edge of a sheet clears it, thereby releasing the vaccum over the rollers 3 and permitting the sheet to drop onto the stack. When the damper is closed, or nearly closed, a high restriction to air flow is provided and the sheet does not drop off. In this case, the previously described size adjusting flaps 53 are replaced by an adjustment rod 91 carrying a baffle 92 at one end. The rod is moved axially to locate the baffle 92 at the required position depending on the length of sheet being used. The baffle 92 thereby separates the suction chamber into two parts. One part has the aperture 90 and the second part has an adjustable suction aperture 93 on the opposite side of the baffle 92. Suction is not released in the second part of the suction chamber when the sheet drops off onto the stack.

In the arrangement shown in FIGS. 17 and 18, the first roller 3b is not driven. In an alternative construction, the roller 3b of FIGS. 17 and 18 may be replaced by the arrangement shown in FIG. 19. In this case the first roller 3c is driven and is a smooth cylinder the same as the other rollers 3. However it is spaced from the next roller by a distance sufficient to provide a low restriction to air flow and the damper valve plate 94 is located between the first and second rollers so that it can be operated to increase the restriction to air flow when a sheet is to be transferred and not deposited. The operation of the modification shown in FIG. 19 is otherwise the same as already described with reference to FIG. 17.

It will be understood that the examples of FIGS. 16-19 may be used in selective stacking arrangements with a plurality of stacking stations of the type shown in FIG. 12. Furthermore, in each case, the complete apparatus includes a number of parallel channels with partitions providing separate suction chambers spaced across the conveyor, as is described with reference to FIG. 14.

The invention thus provides an improved glass sheet transferring apparatus for particular application in automatic warehousing for the selection and stacking of glass sheets on a size selective basis.

Claims

We claim:

1. Apparatus for transferring sheets of glass across an open space defining a transfer path from a first location to a to a second location comprising:

suction means mounted above the transfer path and extending between those locations;

a series of driven rollers mounted in the suction means at a level to project below the bottom of the suction means and each extending transversely of the transfer path, the extent of which projection is such that when a sheet is drawn by suction against the driven rollers the gap between the upper face of the sheet and the bottom of the suction means constitutes an air flow restrictor which creates reduced pressure over the sheet to suctionally hold the sheet against the rollers;

air flow restriction means in the suction means to restrict the flow of air drawn between said driven rollers in the absence of a sheet;

said suction means comprising a suction hood in the bottom of which said series of driven rollers are housed, the hood having an open bottom through which the driven rollers project;

division means in the hood defining a separate release chamber adjacent the second location;

suction control means operable to cut off the suction when a sheet has been transferred to a required second location so that the sheet drops away from the drive elements at that location;

actuating means arranged to be actuated by movement of a sheet to the second location; and

valve means controlled by the actuating means for cutting off the suction in only a part of the suction hood associated with the second location so as to release the sheet when it has reached the second location.

2. Apparatus for transferring sheet material from a first location to a second location comprising:

a suction hood mounted above the transfer path between those locations which hood has an open bottom,

a series of driven rollers mounted in the open bottom of the suction hood and projecting through that open bottom each roller extending transversely of the transfer path,

a suction duct connected to the suction hood for applying suction to the hood to create a reduced pressure over a sheet and thereby draw the sheet against the driven rollers for advancement along the transfer path,

division means in the hood defining a separate release chamber adjacent the second location,

a damper member located in an aperture connecting said release chamber to the main part of the suction hood, and

suction release actuating means connected to the damper means and including a switch device positioned in the transfer path for operation by a sheet as it advances to the second location to cause the actuating means to close the damper member thereby cutting off the suction only in the release chamber so as to release the sheet when it has reached the second location.

3. Apparatus for transferring sheet material from a first location to a second location comprising:

1. a suction hood mounted above the transfer path between those locations which hood has an open bottom,

2. a suction duct connected to the suction hood for applying suction to the hood to create a reduced pressure over a sheet,

3. a series of cylindrical driven rollers mounted in the open bottom of the suction hood and projecting through that open bottom each roller extending transversely of the transfer path, against which rollers a sheet to be transferred is drawn by suction in the hood,

a. the rollers being mounted in closely spaced relationship with the outer driven rollers adjacent the end walls of the hood, and

b. restricted gaps defined between the closely spaced rollers and between the outer driven rollers and the end walls of the hood acting to restrict air flow and prevent undesirably high air flow when no sheet is present beneath the driven rollers,

4. a low resistance air flow passage defined adjacent one driven roller at the beginning of the transfer path so that suction is applied when a sheet bridges that passage and is released when the trailing edge of the sheet passes said one roller thereby depositing the sheet at the second location, and

5. a selectively operable restricting device mounted to restrict said passage when it is required to transfer a sheet past the second location.

4. Apparatus according to claim 3 in which the said one roller in the suction hood comprises two spaced disc members together with an adjustable damper member between them, the damper being adjustable to alter the restriction of the air flow passage between the disc members.

5. Apparatus according to claim 3 in which the gap between the said one roller and the next roller in the suction hood is substantially larger than the gap between other rollers in the hood and an adjustable damper member is located in the larger gap.

6. Apparatus for transferring sheet material from a first location to a second location comprising:

1. an open-bottomed suction hood mounted above the transfer path between those locations,

2. a series of driven rollers mounted in the suction hood and projecting through the open bottom of the hood each roller extending transversely of the transfer path,

3. a suction duct connected to the suction hood to create a reduced pressure over a sheet and thereby draw the sheet against the driven rollers for advancing thereby along the transfer path, and

4. suction control means to release the suction when a sheet has been transferred to a required second location so that the sheet drops away from the driven rollers at that location, including

a. a plate mounted across the hood above the rollers which plate has formed therein at spaced intervals suction paths to the chamber thereby defined in the hood below the plate,

b. a plurality of baffle flaps each pivoted to the plate above one of the rollers, which flaps are selectively movable to close the space between the plate and the roller above which it is pivoted, and thereby subdivide said chamber, the flap moved to the closed position being selected so that the part of said chamber in which suction is released is of length dependent on the length of the sheet being transferred.

7. Apparatus for transferring sheet material from a first location to a second location comprising:

1. an open-bottomed suction hood mounted above the transfer path between those locations.

2. a series of driven rollers mounted in the suction hood and projecting through the open bottom of the hood each roller extending transversely of the transfer path,

3. a suction duct connected to the suction hood to create a reduced pressure over a sheet and thereby draw the sheet against the driven rollers for advancing thereby along the transfer path, and

4. suction control means to release the suction when a sheet has been transferred to a required second location so that the sheet drops away from the driven rollers at that location, including

a. a plate mounted across the hood above the rollers which plate has formed therein at spaced intervals suction paths to the chamber thereby defined in the head below the plate,

b. a slidable baffle member located between the tops of the rollers and said plate and adjustable in position along the succession of rollers to subdivide said chamber so that the part of said chamber in which suction is released is of length dependent on the length of the sheet being transferred.

8. Apparatus for transferring sheet material from a first location to a seocnd location comprising:

1. a suction hood mounted above the transfer path between those locations which hood has an open bottom,

2. a series of driven rollers mounted in the open bottom of a suction hood and projecting through that open bottom each roller extending transversely of the transfer path,

3. a suction duct connected to the suction hood for applying suction to the hood to create a reduced pressure over a sheet and thereby draw the sheet against the driven rollers for advancing thereby along the transfer path,

4. means mounting the last drive roller at the second location for vertical movement to a level below that of the other drive rollers, and

5. actuating means connected to said means for vertically moving the last drive roller arranged in the transfer path to be tripped by a sheet being transferred towards the second location to initiate the lowering of said last drive roller so that the sheet is deposited at the second location.

9. Apparatus for transferring sheets of glass across an open space defining a transfer path from a first location to a second location comprising:

a suction hood mounted above the transfer path between those locations, which hood has an open bottom;

a series of driven rollers mounted in the open bottom of the suction hood and projecting through that open bottom, each roller extending transversely of the transfer path;

a suction duct connected to the suction hood for applying suction to the hood to create a reduced pressure over a sheet and thereby draw the sheet against the driven rollers for advancement along the transfer path;

division means in the hood defining a separate release chamber adjacent to the second location;

actuating means arranged to be actuated by movement of a sheet to the second location; and

valve means controlled by the actuating means and associated with said separate release chamber for cutting off the suction in in the release chamber to release a sheet which thereby drops away from the driven rollers at the second location.

10. Apparatus according to claim 9 wherein the suction hood comprises a plurality of suction chambers each having an open bottom which embraces a driven roller which is thereby housed within its suction chamber and projects through the open bottom of its chamber, each chamber being roofed by an apertured plate which comprises air flow restriction means.

11. Apparatus for transferring sheet material from a first location to a second location comprising:

a suction hood mounted above the transfer path between those locations, which hood has an open bottom;

roller means including a series of driven rollers mounted in the open bottom of the suction hood and projecting through that open bottom, each roller extending transversely of the transfer path;

a suction duct connected to the suction hood for applying suction to the hood to create a reduced pressure over a sheet and thereby draw the sheet against the driven rollers for advancement along the transfer path; and

suction control means, icluding a low resistance suction air flow passage adjacent an end roller, the low resistance air flow passage cooperable with the suction hood, and responsive to the position of a sheet for selectively creating and releasing suction in a portion of the suction hood, and the suction control means being operable during continuous application of suction to the hood by the suction duct.

12. Apparatus according to claim 11 wherein the driven rollers are cylindrical rollers mounted in closely spaced relationship with the outer driven rollers adjacent the end walls of the suction hood, the restricted gaps between adjacent driven rollers and between the outer driven rollers and the end walls of the hood acting to restrict air flow and prevent undesirably high air flow when no sheet is present beneath the driven rollers.

13. Apparatus as claimed in claim 12 in which a low resistance air flow passage is provided adjacent one driven roller at the beginning of the path through the suction hood so that suction is applied when a sheet bridges the low resistance passage adjacent the said one roller but is released when the trailing edge of the sheet passes the said one roller, thereby depositing the sheet at the second location.

14. Apparatus according to claim 11, including an apertured air flow restrictor plate mounted across the hood above the rollers and a plurality of flexible flaps depending from the restrictor plate onto the driven rollers to isolate the space between adjacent driven rollers from each other, the restrictor plate being formed with apertures associated with each isolated space.

15. Apparatus according to claim 14 in which a low resistance air flow passage is provided adjacent one roller at the beginning of the path through the hood so that suction is applied when a sheet bridges the low resistance passage but is released when the trailing edge of the sheet passes the said one roller.

16. Apparatus according to claim 11, wherein said suction control means is operable to cut off the suction when a sheet has been transferred to a required second location so that the sheet drops away from the driven rollers at that location.

17. Apparatus according to claim 16 in which a plate is mounted across the hood above the rollers, suction paths being provided at spaced positions to the chamber below the plate, and baffle means being interposable between a selected roller and the plate between the said suction paths so as to subdivide the suction chamber below the plate and prevent suction being released in one part of the chamber when suction is released in the other part of the chamber.