US2722416A - Separation of sheets of paper or the like from the top of a pile - Google Patents

Description

Nov. 1, 1955 BACKHOUSE 2,722,416 SEPARATION OF SHEETS OF PAPER OR THE LIKE FROM THE TOP OF A FILE 3 Sheets-Sheet 1 Filed May 8, 1951 r A ltom e ys Inventor N v- 1955 H. T. BACKHOUSE SEPARATION 2,722,416 OF SHEETS OF PAPER OR THE LIKE FROM THE TOP OF A FILE 3 Sheets-Sheet 2 Filed May 8, 1951 Inventor Q4 ram Attorney;

Nov. 1, 1955 H. T. BACKHOUSE SEPARATION OF SHEETS OF PAPER OR THE LIKE FROM, THE TOP OF A FILE 3 Sheets-Sheet 3 Filed May 8, 1951 Attorney:

r 0 t n e v n I M TJMMMW United States Patent SEPARATION OF SHEETS OF PAPER OR THE LIKE FROM THE TOP OF A PILE The invention relates to machines for separating sheets of paper, card or other mateiialone at a time from the top of a pile and is concerned withlmachines of the kind in which a suction gripper is lowered ontoeach uppermost sheet in turn and is employed to grip and elevate a portion of the sheet and which comprises a co-operating piston and cylinder (or equivalent bellows or diaphragm and chamber) arranged for suction operation to effect elevation of the gripper, the machine having open connection betweeri'the mouth of the suction gripper and the cylinder when the gripper is lowered to engage a sheet and being so arranged that closing of the mouth of the gripper by engagement with the sheet serves'as a valve sealing the cylinder from the atmosphere and enables suction, usually already applied to the cylinder, to effect relative move ment between the piston and cylinder to raise the gripper with the gripped portion of the sheet. h

' Machines of the above kind are normally used in conjunction with means'for removing the separated sheets from thepile. The removing means may comprise a conveyor and the suction grippermay be arranged, after it has raised a portion of the uppermost sheet of the pile, to rnove in a directionover the top of the pile for the purpose of forwarding the sheet or assisting in the forwarding of the sheet to the conveyor. The conveyor may be arranged to forward the sheets singly or in the form of a stream of partly overlapping or partly underlapping sheets. Machines of the above kind may be employed to feed the sheets to a printing or other machine operating on individual sheets.

In machines of the above kind as at present constructed the suction gripper is carried on the end of a piston rod attached to thepiston and the arrangement is that the suction effects the lifting of the gripper against the reaction of a return spring or other restoring forces.

According to the present invention, the suction gripper in a machine of the above kind is carried on a lever and the piston and cylinder arearranged to rock the lever to efiiect'the liftingof the gripper.

The machine according to the invention has the advantage that a single cylinder may be employed to elevate two or more grippers supported from the lever at spaced positions and the inventionincludes an arrangement in which two or more grippers are elevated in this way.

Further the movement of the gripper may be magnified in relation to themove'ment of the piston and cylinder.'-

In machines of the kind described as at present constructed, it is necessary to eflfect bodily movements of the cylinder with the gripper when it is required to move the gripper over the pile to forward thesheets'. If a cylinder is employed which is made large enough to give a'high rate of lift and asufiicient stroke the weight of such a cylinder introduces considerable inertia forces resisting movement and it is a feature of the present invention that this disadvantage may be overcome or reduced by arranging that the gripper may be moved over the pile independently of the cylinder. For example, the

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gripper may be carried on the end of an arm dependent from the lever aforesaid and means may be provided for imparting a swinging movement to the arm.

It is a further object of a preferred form of the present invention to provide a machine of the above kind having improved mechanism whereby the suction gripper may be lowered to engage and grip a portion of a sheet which has been elevated, by combing, flufiing or other means, from the top of a pile without pressing the sheet back on to the pile and then to move upwardly further to elevate the gripped portion of the sheet.

According to this preferred form of the invention mechanical means are provided which are subject to the overriding control of the suction elevating means, for rocking the lever to lower the gripper at a controlled rate into engagement with a sheet, the arrangement permitting the suction operated piston and cylinder to lift the gripper independently of the lowering means. With this arrangement the gripper may be lowered under accurate control on to the sheet and immediately the sheet is engaged the sealing of the gripper mouth automatically causes the suction means to elevate the sheet.

Preferably the area of the piston and the source of suction are such as to provide a rapid upward movement of the gripper (e. g., faster than it is lowered mechanically).

The mechanical means for lowering the gripper may comprise a cam with a follower on the lever which follower is free to be lifted off the cam when the suction lifting means become operative.

The machine may include means for moving the gripper in a direction over the top of the pile while gripping the lifted sheet thereby to forward or assist in forwarding the sheet to conveying means to remove the sheet from the pile and then to return the gripper and also a valve which, at the end of the forward movement, opens the gripper to atmosphere thereby releasing the sheet without opening the cylinder and at the end of the return movement opens the cylinder to atmosphere through the gripper. The valve may be arranged and operate in the manner described in my co-pending U. S. application Ser. No. 88,861, filed April 24, 1949, now Patent No. 2,591,116, and my British application No. 11098/48, filed April 22, 1948, now Patent No. 674,843.

One specific construction of a machine according to the invention and the method of operation of the machine will now be described by way of example of the invention and with reference to the drawings in which:

' Figure 1 is a side view, partly in section of the machine;

Figure 2 is a plan view of the machine;

Figure 3 is a section on the line III-III in Figure 1, and

'Figure 4 is a section on the line IV-IV in Fi ure 1.

The machine constituting this example is arranged to separate sheets of paper one at a time from the top of a pile 1 and to deliver the sheets on to a conveyor (not shown) where they form a continuous stream of partly overlapping sheets to be delivered to a rotary printing press. The machine embodies a single lifting and forwarding mechanism with suction grippers spaced apart across the width of the pile adjacent the rear edge thereof (i. e., the rear edge considered in relation to the direction of the forwarding movement of the sheets to the conveyor). The mechanism is supported from two bars 2, 3 extending transversely across the pile.

Depending from the above-mentioned bars there is a supporting housing 4 which is clamped to the bars for sliding adjustment along the length thereof. The dependent portion of the housing is forked and embraced within the arms of the fork there is a cylinder 5 having its mouth open and directed downwardly. The cylinder which is of substantial diameter, contains a piston 6 which is urged downwardly by the weight of the mechanism connected thereto as about to be described. A spring may, if desired, be provided to assist in urging the piston downwardly. The piston has a rod 7 which extends upwardly through a guide and at its upper end the rod is provided with a cross-head 8 connected to the two parts, 9, 10 of the bifurcated arm of a bell-crank lever, the two parts embracing the guide and the piston rod. The arm of the bell-crank lever extends approximately horizontally forwardly from the fulcrum 11 of the lever which is behind the guide to, and beyond, the piston rod 7. The fulcrum is provided by a short shaft supported in the two arms of the fork of the housing 4. The other arm 12 of the bell-crank extends downwardly and is provided at its lower end with a follower 13 engageable with a cam 14 which is carried for rotation on a shaft 15 passing through the arms of the bracket and across the pile parallel to the aforesaid supporting rods. To reduce frictional resistance the piston 6 is a loose fit in the cylinder and is guided by the rod 7 in its guide. The arrangement ensures a rapid and substantial lift of the gripper without the need of undue weight movable with the gripper over the pile. Further, by the use of a large diameter cylinder sufficient power is easily made available to provide a rapid stroke even when mechanical multiplication of the movement is employed, thereby allowing the use of a short cylinder with consequent saving in weight. To avoid loss of suction when the piston 6 is at the top of its stroke, a rubber sealing ring 6A is provided on top of the piston and makes sealing engage- I ment with a seat 6B on the cylinder head.

The horizontal arm 9, 10 of the bell-crank lever carries at its front end a dependent parallelogram of links. The parallelogram is pivoted at its top rear corner to the end of the arm. The two downward links 16, 17 are of I double form (one part to each side of the top and bottom links) and at the lower end of the dependent links there is a carrier 18 for a pair of suction grippers 19, the carrier also constituting the bottom link. The top link 20, which extends in a generally horizontal direction forwardly from the pivotal attachment to the bell-crank, also has a downwardly extending arm 21 which is bent forwardly at its lower end to constitute an abutment cooperating with a stop 22 extending between the two parts of the front downward link, thereby to limit collapsing of the parallelogram. A spring 23 extending across the corner between the top link and the stop 22 aforesaid serves to hold the stop against the abutment and to retain the system in a fixed condition during the raising and lowering of the bell-crank arm. This arrangement in conjunction with the cam and push rod later described ensures that the links and grippers are in a defined backward position during the raising and lowering. When the bell-crank is raised, the top link 20 makes contact with the adjustable stop 25 on the supporting bracket, thereby to hold the link during the swinging movement of the downward links and to ensure that the grippers are given a parallel movement as later described.

The two grippers 19 are respectively dependent from the two ends of a cross tube 26 held by the carrier 18 and extending cross-wise of the pile. The cross tube 26 is attached to a slide 27 which may be adjusted in position on the carrier to move the tube 26 in the fore and aft direction of the pile. The arrangement of the carrier and parallel links is that, as the links swing to move the grippers over the pile, the axes of the grippers remain at a substantially constant angle to the top of the pile. The carrier embodies a shuttle valve 30 which is constructed as described in my U. S. Patent No. 2,591,116 and has two positions in which the suction grippers are open to the atmosphere and to a source of suction respectively. The shuttle valve 30 co-operates with stops 31, 32 in the supporting bracket which are positioned respectively for engagement by the shuttle at th mit of the forward swing of the carrier to move the valve to open the grippers to atmosphere while maintaining suction in the cylinder, and for engagement by the shuttle valve 30 at the end of the backward movement to open the grippers to the suction, thereby to admit air to the cylinder and to allow the piston to fall under the control of the cam. As is later described the extent of the swing of the gripper carrier is variable and to accommodate the variations the stops 31 and 32 just described are spring loaded or made adjustable in position and the valve shuttle is arranged to have some latitude of movement.

Pivoted to an arm 34 movable with the rear downward link 16 of the parallelogram about its pivotal support 35 to the bell-crank arm there is a push rod 36 which extends rearwardly and at its rear end is forked to embrace the cam shaft 15. The rod 36 carries a follower 38 co-operating with a further cam 39 on the shaft to effect reciprocatory movements of the rod 36 and consequential swinging movements of the downward links and gripper carrier against the action of a return spring.

The effective length of the arm 34 is adjustable to vary the extent of swing of the gripper carrier. This feature forms the subject of a British application No. 4181/50.

The cylinder 5 is constantly open through a restricted passage 40, pipe 47 and tube 3 to a source of suction, and there is a communication from the cylinder through passageways 42 and the tubular piston rod 7 to the suction grippers 19 to constitute the suction supply to the grippers.

Close behind and between the grippers are two flips 50 at a fixed height (e. g., half an inch) above the pile at the rear edge, but preferably adjustable to the extent to which they extend over the pile. The flips 50 are of springy steel strip and are located between the two grippers and are supported from the bracket 4. The flips prevent the sheets being fiuffed up to the foot (later described) when the foot is fully raised. Two further flips are positioned over the rear corners of the pile respectively to control the sheets immediately beneath the sheet being separated.

There is a second pair of parallel links 60, 61 which are each pivoted to the support bracket 4 at a position behind and above the rear edge of the pile, and which extend forwardly and approximately horizontally one above the other from their pivotal attachments. At their forward ends the links and 61 carry a pressure foot 62 and a pair of dependent air-blast nozzles 63 located one on either side of the foot and behind the top of the pile. The foot has an upward extension 62A which connects to two links. The parallel links ensure that the foot and nozzles may be raised and lowered without change in their angular relations to the pile. A spring 64 urges the foot downward. Attached to the upper link 61 at about the centre of its length there is a vertically extending operating rod 65 formed at its upper end with a yoke surrounding the cam shaft 15. A follower 66 on the rod cooperates with a third cam 67 on the shaft.

The operation of the machine to separate a sheet from the top of the pile is as follows. Initially the foot 62 rests on the top of the pile adjacent to the rear edge thereof. The fiufiing air-blast, which is adjustable in strength to suit different types of stock, is turned on to the nozzles 63 and at the same time the foot 62 and air nozzles are raised by means of the associated cam 67. During the upward movement of the foot 62 the air blasts fluff the uppermost sheets of the pile so that their rear edges tend to rise up to or towards the flips 50 as indicated .in chain lines in Figure l. The foot 62 comes to rest after it has been raised a short distance above the flips (i. e., in the chain line position shown in Figure 1). The suction grippers 19, which are open to suction through the cylinder, are then lowered by the cam 14 engaging the follower on the bell-crank lever to engage the grippers with the portion of the uppermost sheet which has been raised by the air blast (i. e., as shown. in chain lines inFigure 1). Prior to this engagement the cylinder has been open to atmospheric pressure through the grippers and the weight of the parts assisted by a spring has lowered the piston in the cylinder under the control of the cam. Immediately the gripper mouths are sealed by engagement with the sheet, the suction builds up in the cylinder and causes the piston rapidly to rise thereby immediately to lift the grippers even though the operation of the cam may still tend to continue their down movement. This reversal of the movement of the grippers 19 on engagement with the sheet ensures that the sheet is not pressed by the grippers downwardly on to the underlying sheets. The upward movement of the grippers 19 which is at a rate greater than the rate of lowering lifts the sheet and carries it with a bending or breaking action up past the flips 50 which assists in the separation of the sheet from the underlying one.

The grippers 19 engage the sheet a short distance from the rear edge (e. g. the part of the grippers engaging the sheet nearest to the edge may be about one inch from the edge) and the flips 50 extend over the edge a somewhat smaller distance (e. g. about A to of an inch).

After the sheet has been separated in this way the foot 62 is lowered on to the top of the pile and engages the pile under pressure derived from the spring to clamp the remaining sheets against movement. After the sheets have been clamped, an air blast is emitted from the foot and is directed between the partially lifted sheet and the remainder of the pile to complete the separation of the sheet. The grippers 19 are then moved forwardly, carrying the top sheet, by a swinging movement of the parallel links 16, 17 derived from the cam 39 through the push rod 36. When the grippers 19 reach the end of their forward movement the shuttle valve 30 is operated to open the grippers to atmospheric pressure and to close the connection between the grippers and the cylinder 5 thereby to retain the reduced pressure in the cylinder. As a consequence the sheet is released by the grippers 19 to be taken by nipper rolls or other mechanism associated with the conveyor and the grippers are retained in their raised position. The grippers 19 are then swung rearwardly and at the end of this movement the shuttle valve 30 is operated to open the grippers to the cylinder thereby applying suction to the grippers and substantially destroying the reduced pressure in the cylinder. The piston is now free to fall, but the falling movement of the piston and the grippers is controlled by the cam 14 operating on the bell-crank lever so that the grippers 19 are lowered comparatively slowly into engagement with the next sheet which has in the meantime been fluffed-up ready for separation as described above.

The timing of the operations of the two air blasts is approximately as follows: The air blast against the rear edge of the pile to fiufi the sheets operates during the rearward swing of the grippers 19 for a total period corresponding to 60 to 70 of the revolution of the press cylinder and ceases as soon as the top sheet has been gripped. The remainder of the sheets then fall back on to the pile and are clamped by the foot 62. The separating blast from the foot 62 operates from the time that the foot has been lowered on to the sheets, or a little before, for about 60 before the forwarding starts and until the sheet is released by the grippers 19.

It is to be-understood that the invention is not restricted to the constructional details set forth in the above example. For instance, the machine described in the above example is intended for use with sheets of comparatively narrow width. If it is desired to operate on larger sheets the tube 26 may be lengthened (e. g. from about inches up to two or three feet) and there may be two pairs of grippers, one pair at each end of the tube with a separation of about 2 to 2 inches between the grippers of each pair. With this arrangement there will be a flip between each pair of grippers in addition to the two flips one on each side of the foot as described above. The additional flips may be supported from the bars 2 and 3. Alterna-' tively for use in separating large sheets there may be two devices as described above spaced apart across the rear of the pile. Again the fiuifing nozzles may be arranged to direct air obliquely on to the rear of the pile to increase the spread of the air and/or the nozzles may be further distributed over the rear of the pile. Further, it is within the invention so to modify the above example that the two parts of the double parallel links carrying the grippers are spaced apart outside the side edges of the sheets respectively and are carried for swinging movement near the side frames of the machine. With this arrangement, the grippers may be carried on a cross-link extending over the top of the pile from one link part on one side frame to the other link part in the other side frame, the suction cylinders remaining at the centre of the width of the pile and being connected by a cross-member to the links.

The above example relates to a machine and conveyor arranged to produce, on the conveyor, a continuous stream of sheets. The arrangement may, however, be varied (e. g. by increasing the speed of the conveyor) so that the sheets are conveyed individually.

I claim:

1. A machine for separating sheets from the top of a pile, comprising a frame, a suction gripper for gripping each uppermost sheet in turn, and means for elevating the gripper while gripping a sheet; said means comprising a lever pivoted to the frame, means attaching the gripper to the lever at one position spaced apart from the pivot, and a suction operated contracting device connecting the lever to the frame at another position on the lever spaced from the pivot to rock the lever to lift the gripper on contraction of the device by building up of suction therein, the said device being arranged for continuous connection to a source of suction and having a connection to atmosphere through the gripper whereby sealing of the gripper by a sheet causes suction to be applied to the device to contract the device, and means for releasing the suction in the device.

2. A machine as claimed in claim 1, in which the lever is pivoted to the frame at one end of the lever, the gripper is attached to the other end of the lever and the contracting device is connected to the lever intermediate between the ends thereof.

3. A machine as claimed in claim 1, in which the contracting device is a suction operated piston and cylinder.

4. A machine as claimed in claim 1, in which the attachment means for the gripper to the lever permit movement of the gripper over the pile independently of the lever and contracting device and in which means are provided for effecting such movements of the gripper.

5. A machine as claimed in claim 1, in which the gripper is carried on the lower end of an arm dependent from the lever and in which means are provided for imparting swinging movements to the arm thereby to move the gripper over the pile independently of the lever and contracting device.

6. A machine as claimed in claim 1, in which the lever is impositively urged in the direction to lower the gripper onto the pile and in which mechanical means for controlling the rate of descent are provided.

7. A machine as claimed in claim 6, in which the mechanical means for controlling the rate of descent of the gripper comprise a cam with a follower on the lever, which follower is free to be lifted off the cam when the contracting device becomes operative to lift the gripper.

8. A machine for separating sheets in turn from the top of a pile comprising, a frame, a lever pivotally supported by said frame for movement about a substantially horizontal axis, a suction gripper for gripping each uppermost sheet in turn, pivoted link means attaching the gripper to the lever at one position spaced therealong from the pivot, the lever being urged to rotate about its pivot in a direction to lower the gripper, abutment means abutting against the lever to limit rotation of the lever about its pivot in said direction, means for moving said abutment means to permit controlled movement of the lever about its pivot in said direction, thereby to lower the gripper towards the uppermost sheet of the pile, a suctionoperable lifting device connecting the lever to the frame at a second position spaced along the lever from the pivot, whereby on operation of said device the lever is rotated about its pivot in the opposite direction away from the abutment means thereby to raise the gripper, the device being arranged for continuous connection to a source of suction and having a connection to atmosphere through the gripper whereby sealing of the gripper by a sheet causes suction to be applied to said device to operate said device, whereupon the sheet is lifted by raising of the gripper as aforesaid, means for moving the gripper relative to the lever across the pile to feed the sheet there- References Cited in the file of this patent UNITED STATES PATENTS 2,085,612 Spiess June 29, 1937 2,215,458 Backhouse Sept. 24, 1940 2,341,521 Baker Feb. 15, 1944 2,591,116 Backhouse Apr. 1, 1952

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