GB2195618A - Separating sheet material - Google Patents

Abstract

Sheet material 1 is separated from a stack 2 by apparatus comprising a body member A which includes the needle carrier 4 having a front face which in use overlies sheet 1 to be picked up. Needles 6 may be mounted on a common needle support head 10 driven reciprocally by a vacuum source connected to opening 23. When vacuum is applied, the head 10 moves downwardly so as to drive the needle at an inclined angle into the sheet 1. The body member A can then be raised to transport the sheet to another location. The sheet 1 may be released from the needles by disconnecting the vacuum source so that spring 20 causes the needles to retract from the sheet. Suction cups may be provided in addition to the needles. The needles may be driven electrically rather than by vacuum. <IMAGE>

Description

SPECIFICATION Apparatus for selectively engaging sheet material This invention relates to apparatus for selectively engaging sheet material and has particular but not exclusive application to apparatus for separating one sheet or a predetermined greater number of sheets of material, from a multiplicity of sheets.

it is known in the art to separate or lift off sheets of material by picking them up with suction cups or utilising needles pushed on a perpendicular path into the sheets. Suction cups are unreliable or ineffective for this purpose if the material is porous e.g. cloth or some types of paper, or if the sheet surface is uneven. Needles, as used in the prior art, are -unreliable because of the difficulty of determining and controlling the depth of penetration required to ensure reliable lifting of a single sheet or the desired number of sheets.

Also, the needles may part from the sheet(s) without producing a lifting action, or may require barbed ends in order to be effective, which may damage the sheets.

With a view to overcoming these difficulties, the present invention provides apparatus for selectively engaging sheet material comprising a body member, a needle movably mounted on the body member, and actuator means for moving the needle to cause inward and outward movement thereof relative to the body member such that upon said outward movement the needle enters the sheet to be engaged along a path that is inclined to the plane of the sheet so as to grip the sheet for transport, and upon said inward movement the sheet is released from the needle.

Preferably, a plurality of needles are provided, the tips of which move away from one another upon said outward movement thereof.

The actuator means can be arranged to operate to drive the needles outwardly by an amount suitable to pick up a single sheet from a pile thereof. Thus, in use, the body member may be positioned over a pile of sheets, the actuator means operated to cause said outward movement of the needles. so that they are driven into the uppermost sheet only. The body member can then be moved from this pick up station to a depositing station at which the actuator means causes said inward movement of the needles so as to release the picked up sheet.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 illustrates diagrammatically elements of a first embodiment of the invention and their directions of motion; Figure 2 is a schematic partially sectioned side view of the first embodiment of apparatus according to the invention; Figure 3 is a schematic vertical section of a second embodiment of apparatus according to the invention; and Figure 4 is an end view of the second embodiment, in partial section.

Referring firstly to Figure 1, a sheet 1 is to be separated from a plurality of sheets 2 in a pile and lifted in direction 3. The apparatus according to the invention includes a body member indicated generally by reference A and includes a carrier 4 having a face 5 which abuts against sheet 1. The carrier 4 acts as a guide for needles 6 which can be caused to make outward movement in direction 7 into the sheet 1, as shown in Figure 1. This results in the sheet 1 being gripped by the needles for transport. The needles can also be removed in direction 8 to release and deposit the sheet 1. The body member A can be moved in the direction 9 so that after sheet 1 has been picked up at a pick up station as illustrated in Figure 1, the body member A can be moved to a depositing station (not shown) at which the needles 6 are withdrawn to release the sheet.It will be appreciated that the body member A can be moved in a direction transverse to the plane of the sheet 1 (Figure 1) in addition to the perpendicular direction 9 shown.

In Figure 2, the structure of the apparatus is shown in more detail. The needles 6 are mounted on a common needle support or head 10 which is mounted for reciprocal movement on a rod extension 12 of the carrier 4. The needles 6 terminate in resilient capsules 13 which are mounted in screw adjusters 14 so that the tips 15 of the needles can be set so as to be flush with or below the face 5 of the carrier 4 when the needles are in their retracted position. The needles 6 are slidably mounted in guide slots 16 in the carrier 4 and pass over a curved heel 17.

The rod extension 12 acts as a piston 18 in the head 10. The rod extension 12 is partially bored out at 19. A compression spring 20 acts against the piston 18 in a recess 21 in the head 10, the head being held in place by a threaded locking ring 22 secured to a correspondingly threaded end portion of the rod extension 12.

A vacuum source (not shown) is connected to open end 23 of the bore 19. Transverse bores 24 communicate the vacuum to the cylinder defined by recess 21 and piston 18.

Gaskets 25, 26 are provided to seal the evacuated recess 21 from atmospheric pressure.

It will be seen that the needles extend to diametrically opposed positions on the carrier 4, the needles being inclined to the plane of the carrier face 5 and extending through an aperture 27 in the rod extension 12.

Prior to use, i.e. when no vacuum is applied to opening 23, the screw adjusters 14 for the needles are operated to bring the tips 15 of the needles flush or recessed behind the car rier face 5. The body member A is then positioned over sheet 1, as shown in Figure 2. At this time, no vacuum is applied to opening 23 and as a result the compression spring 20 urges the head 10 against the locking ring 22.

The vacuum source is then switched on which causes the head 10 to move downwardly against the force of the compression spring 20 so that the tips 15 of the needles are driven into the sheet 1. The presetting of the screw adjusters 14 is so arranged that the tips are driven solely into sheet 1, i.e. not into sheet 2. It will be seen that the needles move outwardly along a path which is inclined to the plane of the sheet 1 and also the plane of carrier face 5. It will be seen that the tips of the needles 6 move away from one another as a result of this outward movement which causes the sheet 1 to be gripped positively by the needles such that it cannot readily fall off when the body member is subsequently lifted in direction 9.

The body member can then be moved to a depositing station at which the vacuum source is disconnected to cause the needles 6 to be withdrawn inwardly of the carrier 4. As a result, the sheet 1 is released and allowed to fall free from the carrier 4.

Whilst the arrangement has been described picking up a single sheet 1,' it will be appreciated that the screw adjusters 14 could be set to pick up a predetermined multiple number of sheets if desired.

We have found that in the action just described, the tips 15 of the needles 6 follow a slightly curved path. This can be advantageous to the process. If desired, the needles 6 may be made curved near the tips 15 so as to follow their path more precisely.

Figures 3 and 4 show a more practical embodiment of the invention. This second embodiment is operated by positive pneumatic pressure rather than a vacuum as in Figures 1 and 2. The body member B shown in Figures 3 and 4 consists of a generally cylindrical housing portion 28 with a conical needle guide surface 29, to which is attached a circular face plate 30. Needles 6 are each attached at one end to a common support member in the form of a cylindrical plunger 31 slidably received for reciprocation on a fixed tubular post 32 upstanding from the face plate 30.

The needles 6 each have a main portion 6a extending generally parallel to the axis of the plunger 31 and a splayed portion 6b which is inclined to the exterior plane surface of face plate 30.

The splayed portion 6b is arranged slidably to engage an inclined guide surface 30a on the side edge of the face plate 30.

A rubber diaphragm 33 is sealingly clamped between the cylindrical housing portion 28 and a generally circular closure portion 34 that defines a plenum communicating with bore 35 in a-mounting shaft 36. The bore 35 is connected to a pneumatic pump through a control valve (not shown). Normally, the diaphragm 33 remains flat as shown in the drawing but upon application of pneumatic pressure through bore 35, is biassed downwardly thereby pushing the plunger 31 downwardly and hence moving the needles generally downwardly such that the splayed ends 6b slide against the inclined surface 30a, causing the needle tips to move downwardly and also outwardly relative to one another, to protrude from the body member B. A compression spring 37 maintains the plunger 31 in contact with the diaphragm 33 and hence withdraws the needles into the body member B when the pneumatic source is switched off.

The stroke of the plunger 31 is controlled by means of an axial post 38 which is adjustably threadingly engaged in the face plate 30.

The post 38 is provided with a screw driver slot 39 and a locking nut 40, which enables the axial extent of the post to be adjusted.

Thus, in use, the body member B is positioned with the face plate 30 overlying sheets of material to be picked up, in the manner generally shown in Figure 2 and the pneumatic source is switched on so as to deform the diaphram 33 downwardly, so as to urge the plunger 31 downwardly, thereby causing the splayed ends 6b of the needles to move outwardly of the body member along the inclined paths into the sheet of material to be picked up. The depth of penetration can be adjusted by prior adjustment of the post 38.

Control means (not shown) can be used to move the body member B from a pick up station to a depositing station at which the pneumatic source is switched off such that the diaphragm 33 returns to its unextended position thereby withdrawing the needles and releasing the sheet.

Many modifications and variations falling within the scope of the claimed invention will be apparent to those skilled in the art. For example where the nature of the sheet material makes it advantageous, suction cup or cups may be provided in addition to the needles. Such an arrangement may be advantageous with the embodiment described with reference to Figures 1 and 2 since the vacuum supply can be used for both actuating the needles and the suction cup.

In another modification, the needles are driven electrically rather than by means of a pressure differential.

The described embodiments of the invention have particular application to fabric handling machines but also can be used for handling other types of sheet material.

Claims (23)

1. Apparatus for selectively engaging sheet material, comprising a body member, a needle movably mounted on the body member, an actuator means for moving the needle to cause inward and outward movement thereof relative to the body member such that upon said outward movement the needle enters the sheet to be engaged along a path that is inclined to the plane of the sheet so as to grip the sheet for transport, and upon said inward movement the sheet is released from the needle.

2. Apparatus according to claim 1 including a plurality of said needles each for movement along a respective said inclined path.

3. Apparatus according to claim 2 wherein the tips of the needles move away from one another upon said outward movement.

4. Apparatus according to claim 3 wherein the tips each move along a respective curved path.

5. Apparatus according to claim 2, 3 or 4 wherein said body member includes needle guide means providing a plurality of needle guides which receive the needles respectively, a common support member on which said needles are mounted, and said actuator means includes means for driving the common support member towards and away from the needle guide means whereby to move the needles collectively.

6. Apparatus according to claim 5 wherein said actuator means includes means responsive to an applied pressure differential for moving said support member in a first direction relative to the needle guide means, and spring means urging the common support member in a second, opposite direction relative to the needle guide means.

7. Apparatus according to claim 6 wherein said first and said second directions are toward and away from the needle guide means respectively.

8. Apparatus according to claim 6 or 7 wherein said pressure responsive means comprises a piston and cylinder assembly.

9. Apparatus according to claim 6 or 7 wherein said pressure responsive means comprises a resiliently deformable diaphragm which acts upon said common support member.

10. Apparatus according to any of claims 2 to 9 wherein said body member presents a face for abutting said sheet material, and said needle means are movable from a position wherein the tips thereof do not protrude beyond the face so as to release the sheet material, to a position protruding from the face for engaging the sheet material.

11. Apparatus according to claim 10 wherein said- needles are arranged in a ring around said face.

12. Apparatus according to any one of claims 2 to 11 including adjustment means for adjusting the outward movement effected by the needle means.

13. Apparatus according to claim 12 when appendant to claim 5 wherein the adjustment means comprises an adjustable stop to limit movement of the common support member.

14. Apparatus according to claim 12 wherein the adjustment means comprises adjustable mountings for the needles respectively whereby the needles can be adjusted individually.

15. Apparatus according to any preceding claim including a pick up station to receive a pile of sheets to be separated, a depositing station for the sheets, and control means for moving the body member between said stations and operating said actuating means in such a manner as to pick up a sheet at the pick up station and then release the sheet at the depositing station.

16. Apparatus according to claim 15 and so arranged as to pick up a single sheet from the pick up station.

17. Apparatus according to claim 15 and arranged to pick up a predetermined plurality of sheets.

18. Apparatus according to any preceding claim wherein the needles have curved ends.

19. Apparatus for selectively engaging sheet material, substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.

20. Apparatus for selectively engaging sheet material, substantially as herein described with reference to Figure 3 and 4 of the accompanying drawings.

21. A method of picking up sheet material with apparatus according to any preceding claim, including moving the needle outwardly of the body member into a sheet of material, transporting the body member whereby to transport the sheet, and thereafter withdrawing the needle into the body member to release the sheet.

22. A method of picking up sheet material substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.

23. A method of picking up sheet material substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.