US2341521A

US2341521A - Sheet feeding apparatus

Info

Publication number: US2341521A
Application number: US381646A
Authority: US
Inventors: Baker Leonard; Leo C Williams
Original assignee: Dexter Folder Co
Current assignee: Dexter Folder Co
Priority date: 1941-03-04
Filing date: 1941-03-04
Publication date: 1944-02-15
Anticipated expiration: 1961-02-15

Description

Feb. 15,1944. l.. BAKER ETAL SHEET FEEDING APPARATUS Y Filed March 4, 1941 l INVENTORS LEONARD BAKER LEO C. WILLIAMS AGENT Patented Feb. 15,` 1944 UNITEDASTATES PATENT oFFici-z SHEET FEEDING APPARATUS Leonard Baker, Hillsdale, N. J., -andi'ieo C. Williams, Pearl River, N. Y., assignors to Dexter" Folder Company, Pearl River, N. Y., a corporation of New York Application March 4, 1941, Serial No. 381,646

23 Claims. A(Cl. 271-26) This Ainvention relates to sheet feeders and more particularly to sheet handling devices thereof comprised by suction sheet separators and forwarders.

One object, of the present invention is to pro- Y, vide improved vacuum operated suction sheet handling? devices of the telescoping type which,

while capable of acting on paper, cardboard, thin metal and other relatively light sheets, are particularly adapted for acting on thick metal, fibre board, plywood, pressed wood and other relatively heavy sheets.

Another object vof the present invention is to provide a sheet feeder having improved vacuum operated suction devicesv of the telescoping type which are capable of separating and forwarding thick metal, fibre board, plywood, pressed wood and other relatively heavy sheets from a pile or supply thereof.

Another object of the present invention is to provide improved vacuum operated suction sheet handling devices of the telescoping type which are relatively small in size and yet capable through the provision of novel means incorpo.

rated therein of lifting thick metal, ibreboard,

plywood, pressed wood and other relatively heavyv sheets from a pile or supply thereof.

Another object of the present invention is to substantially increase the power of a vacuum operated suction sheet handling device without 4 an increase in the size of the piston.

showing said parts in the positions they occupy after a sheet has been lifted and vacuum is broken in the device.

Referring to the drawing, wherein like reference characters designate like parts throughout the several4 views, 5 indicates a frame comprised at opposite sides of the feeder by front 'uprights 6 and rear uprights i connected together by side members 8. A pileV board 9 and pile of metal or other sheets I ar supported in the feeder on a pile elevator (not shown) which is of well known construction and operation and needs no detail description herein except to say that as sheets are fed ofi the top of the pile, the elevator 'and pile board 9 are intermittently raised in the usual manner to keep the top of said pile at a proper level for separation and feeding of sheets therefrom.

The sheets of pile Il) are separated one after another from the top and rear thereof by separating devices located ladjacent the rear corners of the pile and actuated inV opposite directions by vacuum to engage and lift the vrear portion of the topmost sheet. The separating devices, indicated broadly at II. are carried by brackets I2 which are mounted on, and slidable along, a rear cross member I3. This cross member I3 forms part of an auxiliary frame I4 which includes side members I5. The auxiliary frame I4 is pivotally mounted at opposite sides ofthe feeder, as at I6, on brackets I1 which are bolted or otherwise suitably secured to the vside members 8. The auxv illary frame Il is supported at the rear thereof to the accompanying drawing which illustrates one embodiment thereof.

In said drawing `Fig. 1 is a `fragmentary vertical longitudinal sectional view of a sheet feeder embodying the present invention;

Figs. 2 and 3 are enlarged llongitudinal sectional views of one of the vacuum operated telescoplng suction sheet handling devices illustrated in Fig. 1, and showing certain parts thereof in the positions they occupy when a sheet is engaged and lifted from the top of the pile; and

Fig. 4 is a viewl similar to Figs. 2 and 3 v but by pins I8 secured in any suitable manner in the rear uprlghts 1.

Each sheet separated by the separating devices II is advanced from the pile by forwarding devices located adjacent the front of said pile and actuated in both directions by vacuum to engage and lift the front portion of the separated sheet. The forwarding devices, indicated broadly at I9. have swinging movement to advance the separated sheets, and for this purpose said devices are secured to arms 20 fixed on a rock shaft 2| Awhich extends transversely of the feeder and is journalled in suitable bearings in the brackets I1. The sheet forwarding devices I9 are rocked rearwardly by a spring (not shown) and forwardly by a cam 22 xed on a. cam shaft 23 which extends transversely of the feeder and is journalled in suitable bearings in the front uprights 6. The cam shaft 23 is driven in any suitable manner by any suitable source of power, as for example, the printing press or other machine with which the feeder is associated. The cam 22 engages a roller 24 iournalled on a cam strap 25 extending over the cam shaft 23 and connected with an arm 26 which is fixed on the rock shaft 2|.

Each sheet separated from the pile by the sheet separating devices is 'taken by -the sheet forwarding devices I3 and delivered thereby to a conveyor comprised by` a driven feed roller 21 which extends transversely of the feeder and is journalled in suitable bearings in the front uprights 6. roller 21 .are drop rollers 23 journalled on arms 23 which are fixed on a rock shaft 35. The rock shaft 35 extends transversely ofthe feeder and is iournalled at opposite ends thereof in suitable bearings in plates 3| which are bolted or otherwise suitably secured to the front uprights 3. 'I'he drop rollers 28 are raised and lowered in the usual manner once during each cycle of operation of the feeder to receive each forwarded sheet delivered between said rollers and the feed roller 21 and thereafter assist feeding of the sheet by the feed roller toward the machine or instrumentality to be fed.

The suction sheet separating devices and thel suction sheet forwarding devices i8 are identical as respects their construction and sheet engaging and lifting operation and a description of one of said devices will therefore be suiiicient for all of the same. These suction devices are, in accordance with thev present invention, each preferably constructed and operated as follows. Referring now more particularly to Figs. 2, 3 and 4, each suction device includes a cylinder 32 which is relatively small in diameter and'closed at its upper and lower ends by

caps

33, 34. respectively, secured in any suitable manner in said cylinder. Slidably mounted in the lower cap 34 of the cylinder 32 is a hollow piston stem 35 which is open at both ends and projects through said cap beyond the same. Fixed on the projecting end of the hollow piston stem 35 exteriorly of the cylinder 32 is a rubber suction cup 36 provided with a duct 31 connecting said cup and said hollow stem through the lower open end oi' the latter.

Blidably mounted in the cylinder 32 and secured to or formed integrally with the hollow piston stem 35 at the other end thereof is a piston head 38 provided with a skirt 38. Surroimding the hollow piston stem 35 and interposed between the piston head 38 and the cap 34 is ya light compression spring 46 adapted to hold said head, said stem and the suction cup 35 in their normal full line positions shown in Figs. 1 and 4 when no vacuum is created in the cylinder 32. In order to prevent the piston head 38 from becoming air bound at the top of the cylinder 32, a boss 4| extends slightly above lsisligid head and is provided with slots 42 or the The cylinder 32 is provided longitudinally thereof with a chamber or connection 43 the lowerend of which has a port 44 for establishing communication between said chamber and the interior of said cylinder beneath the piston head 38. The upper end of the chamber 43 communicates with a port 45 which is formed in the upper cap alinement with said chamber. 'I'his port 45, in turn, opens into a cylindrical bore or valve chamber 46 which is preferably formed in, and extends horizontally through. the cap 33. The cylindrical bore 46 in cap 33 is closed at one end thereof by a cover plate 41 and at-its opposite` end by a cover plate 48 which ispro-r Cooperating with the feed 33 and disposed in vertical' vsaid valve element.

vided with a relief port 48 in communication with said bore and opening outwardly to atmosphere. The

cover plates

41 and 48 are secured to the 'cap 33 by machine screws 50 or the like. The cap 33'has alsov formed therein a port 5| which is spaced from the port 45 and establishes -communication between the bore 46 in said cap' and the interior of the cylinder 32 above the piston head 38. Connected lwith the cap 33 and communicating with the bore 46 therein is one end of a flexible conduit 52 the opposite end of which is connected with a vacuum pump (not shown) or other suitable source` of vacuum through a suitable valve mechanism (not shown) which controls the making and breaking of -vacuum in the cylinder 32 at predetermined intervals.

Fitted for reciprocation in the cylindrical bore or valve chamber 46 is a valve member 53 provided at one end thereof-with a reduced portion 54, and intermediate its ends with a re- 'duced portion 55 which forms spaced

valve elements

56 and 51. The valve element 56 is provided near its periphery with a port 58 which preferably is somewhat smaller in diameter than the port 45 and extends horizontally through This port 58 establishes communication between the iiexible conduit 52 and the upper end of the cylinder 32 through the reduced portion 55 of valve member 53, the bore 46 and the port 5|. A light compression spring 53, encircling the reduced portion 54 of valve member 53 and interposed between the latter and the cover plate 41, normally tends to move the valve member toward the right (Figs. 2, 3 and 4) so that the relief port 49 in cover plate 48 is normally closed by the valve element 51 and the port 45 in cap 33 is normally in communication with the flexible conduit or source of vacuum 52 through the bore 46 and the reduced portion 55 of said valve member as shown in Fig. 4 of the drawing.

Any suitable means may be provided for adjusting the size of the connection between the atmosphere and the lower end of the cylinder 32 whereby the speed of the lift of the piston head 38 may' be controlled. The' means particularly illustrated for accomplishing this result will now be described. Movement of the valve member 53 toward the left (Figs. 2, 3 and' 4) by vacuum as hereinafter described, is limited by a stop member preferably in the form of a, machine screw 60 which is threaded in the cover plate 41 and adapted to be engaged by the reduced portion 54 of said valve member. By turning the stop member 60 in opposite directions the extent of movement of the valve member 53 in the bore 46 as aforesaid may be varied so that more or less of the port 45 in cap 33 is covered or uncovered by the valve element 51 as shown in Fig. 3 of the drawing, thereby controlling the speed of upward movement of the piston head 35. The stop member 60 may "be locked in adjusted positions by a lock nut 6|. 'I'he operation of the suction device which has just been described is as follows. When vacuum is created in the flexible conduit 52, and with the parts of the suction device in their normal positions shown in Fig. 4, vacuum is likewise created in the lower endl of the cylinder 32 through the cylindrical bore 45. the reduced portion 55 of valve member 53, the port 45, the chamber 43 and the port 44. Vacuum so created in the lower end of the cylinder 32 and beneath the piston head 3l causes said head, the piston stem 35 and the sucasentar tion cup 36 to move downwardly, compressing the spring 40, until the suction cup engages the top sheet of the pile l as shown in Fig. 2 of the drawing. The vacuum in the conduit 52 also draws air through the port 58 in the valve element 55, port l, cylinder 32, hollow stem 35 and duct 3l in the suction cup 36. However, the port 58 is small enough so that this air infiltration does not. reduce the vacuum pressure materially and hence suicient vacuum pressure is created upon the lower side of the piston head 33 so that it and the suction means move downwardly, as described, against the pressure of the compression spring 40. No vacuum or substantially no vacuum is created over the top of the piston head 38 and to the left of the valve element 55 because the duct 3l' in the suction cup 36 is open to atmospherc. However, when the suction cup 35 engages the top sheet of the pile, it is sealed thereby and a vacuum is then created in the suction cup so that the top sheet is held thereby. Immediately upon sealing of the suction cup 35 by the top sheet of the pile, vacuum will also be created in the upper end of the cylinder 32 and in the piston stem 35 and suction cup 36 through the bore t6, the reduced portion 55 of valve member 55, and the ports 5B and 5l in the valve element 55 and cap 53, respectively.

As shown in Fig. 3, when vacuum is created in the upper end of the ,cylinder 32 and in the cylindrical bore or valve chamber 55 because of the sealing of the suction cup 36 by the sheet, atrnosn pheric air pressure through the relief port e9 acts on the right face of the valve element 5l and pushes the valve member 53 toward the left until the reduced portion 55 of said valve member engages the stop member Bil. Under these conditions, the valve element 5l is moved away from the relief port @d in cover plate 158 and beyond the port 55 in cap 33 thus breaking the connection between the source of vacuum 52 and the lower end of the cylinder 32 and at the same time establishing communication between said ports and opening the lower end of the cylinder to atmosphere through the port M, the chamber d5, the port 55, the bore t5 andthe relief port de. Even though the valve member 55 has moved and opened atmospheric pressure to the lower side of the piston head 38, the vacuum connection between conduit 52 and the top of the cylinder 32 remains connected to apply vacuum therein. A. condition exists then in which the top of the piston head 38 has vacuum applied thereto and air pressure is'applied to the piston area surround' ing the piston stem 35 upon the underside thereof by virtue of the atmospheric connection through the relief port 59. Since atmospheric pressure already exists upon the area of the piston stem 35 exterior of the cylinder 32 and is now applied also to the area upon the underside of the piston head 38 within the cylinder, the effective area upon which atmospheric pressure is applied is now equal to the piston area in the upper end of the cylinder upon which vacuum is applied. The

power in the return stroke is also augmented somewhat by the compression spring 50( Heretofore, the power in the return stroke was represented by the atmospheric pressure on the. piston stern alone, augmented, of course,.by the com pression spring, because vacuum was retained within the lower portion of the cylinder or under the piston head. The return power of the piston head 35 has been increased, therefore, by the diderence between atmospheric pressure and vacuurn pressure applied upon the underside of the piston head over that portion of the piston area around the piston stem 35.

Whenl vacuum has been created in the upper end of the cylinder 32 as herenbefore described, the piston head 33, the piston stem 35, and the suction cup 35 are raised and the top sheet which is heldto the suction cup by vacuum is lifted from the pile I0, as shown in dotted lines in Fig. 3, which lift is aided by strength of the spring lili. The sheet handling device will function under the vacuum and atmospheric pressure applied to the piston head 33 regardless of the spring dll which assures the piston head remaining at itsrup position when no vacuum is created in the cylinder 32. Vacuum is broken in the flexible conduit 52 to release the lifted separated and/or forwarded sheet from the suction cup 36 whereupon. the spring 59 in the valve chamber or cylindrical bore 55 acts through expansion thereof to return the valve member 53 to its original position shown in Fig. 4 so that the suction device can be again operated by vacuum, as described, during the next cycle of operation of the feeder.

The speed of upward movement of the piston head 38 `as hereinfore described, is controlled by the size of the opening for admi-tting air into the lower end of the cylinder 32 through the port l5 when communication is established between said port and the relief port 59 through movement of the valve member 53. Any suitable means may be utilized for controlling the size of the connection between atmosphere and the lower end of the l cylinder 32 and hence the speed of lift of the piston head 35. In the construction illustrated, the port 55 may be completely uncovered bythe valve element 5l in which case thepiston head 38 will move upwardly at maximum speed, and when the port l5 is more or less covered by the valve element 5l the speed of upward movement of the piston head 33 will be accordingly slower. The speed at which the piston head 38 is to operateis governed by the weight and condition of the sheet material to be lifted by the suction cup 35, and may be varied, as desired, to suit various conditions by loosening the lock nut 6I and adjusting the stop member 60 toward or away from the valve member 53, thereby varying the extent offmovement of said valve member in the cylindrical bore 43 so that more or less of the port i5 is covered or uncovered by the valve element 5l.

The valve means 53 described normally connects the flexible conduit 52, which is adapted to be connected to a source of vacuum,V with the lower end of the cylinder 32. When vacuum -is ,created in the upper end of the cylinder 32, in the suction means 35, 35 and in a vacuum 'chamber at the left of the valve element 56 by a sheet sealing the suction means', the valve means 53 is then operatedto the left (Fig. 3) to disconnect the lower end of the cylinder from the source of vacuum 52 and connect the same with atmosphere or atmospheric pressure through the relief port 55. The valve means 53 is retained in operated position so long as vacuum exists in the suction means 35, 55j When vacuum is broken or disconnected at the desired time to release the sheet from the suction cup 3G, the valve means 55 is restored to its normal position in any suitable fashion, such as by the spring 59, and the device is ready for a second cycle of operation` Although the valve element 5l performs the double function described above, it is-clear that other means may be provided to perform these two functions.

The sheet handling device described herein opy crates by applying diierential pneumatic pressures to the opposite sides of the piston head 38. For example, the piston head 38 is moved downwardly by creating a higher pneumatic' pressure upon the top thereof under the control of valve means connected with the inlet conduit 52.

When the suction means or cup 36 is sealed by a sheet, the vacuum created therein operates the valve means 53 in the cap 33 to create or secure a higher pneumatic pressure in the lower end of the cylinder 32, whereupon the piston head 38 moves upwardly to raise the suction means and the sheet carried thereby.

'I'he head 33 with its valve means 53 constitutes a new article of manufacture which can be mounted upon an existing cylinder andl piston type suction means to convert the same into a more powerful sheet handling device, as described herein Because of the `increased power of the piston or motor described herein, thick-metal, iiberboard, plywood, pressed wood and other relatively heavy sheets can be lifted from a pile or supply thereof.

The present description and accompany drawing set forth with more or less particularity one embodiment of the present invention, but it is to be expressly understood that said invention is not limited to said embodiment or otherwise than by the terms of the appended claims.

What we claim is:

l. In a sheet handling device of the type having suction means which is reciprocated by .a piston operating in a cylinder which is adapted to be connected with a source of differential pneu- A matic pressures to reciprocate the suction means to engage and lift a sheet: the improvement comprising means controlled by the sheet sealing the suction means and actuated by the vacuum created therein for applying a differential pneumatic pressure in the lower end of the cylinder as compared to the pneiunaticpressure in the upper end of the cylinder whereupon lifting of said suction means and the sheet engaged thereby is effected.

2. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising means controlled by the sheet sealing the suction means for opening the lower end of the cylinder to atmosphere whereupon lifting of said means carried by the piston stem, the piston being vacuum reciprocated to cause the suction means to engage and lift a sheet: the improvement comprising means operated when the suction means v engages the sheet for closing the connection between the vacuum supply and the lower end of the cylinder yand opening the same to atmosphere and remaining in operated position so long as vacuum is supplied to the device. l

6. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvementl comprising means controlled by the sheet sealing the suction means forr closing the connection between the vacuum supply and the lower end of the cylinder and opening the same to atmosphere and remaining in operated position so long as vac, uum is supplied to the device.

7. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated' to engage and lift a sheet: the improvement comprising means controlled by the sheet sealing the suction means for closing the connection between the vacuum supply and the lower end of the cylinder and opening the latter to atmosphere whereupon lifting of said suction means and the sheet engaged thereby is effected.

.8. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement com-- prising means actuated by the vacuum created when the sheet seals the suction means for closing thev connection between the vacuum supply 1 and the lower end of the cylinder and opening the suction means and the sheet engaged thereby is effected.

3. In a sheet handling device of the type havy ing a cylinder and piston type suctlon'means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising vacuum actuated means controlled by the sheet sealing the suction means for opening the lower end of the cylinder to atmosphere whereupon lifting of said suction means and the sheet engaged thereby is eiected.

4. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising means controlled by the sheet sealing the suction means for opening the lower end of the cylinder to atmosphere whereupon lifting of the suction means and the sheet engaged thereby is effected, said means also controlling the speed of upward movement of the suction means.

latter to atmosphere whereupon lifting of said suction means and the sheet engaged thereby is effected.

9. In a sheet handling device of the type having -a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising means controlled by the sheet sealing the suction means for closing the connection between` the vacuum supply and the lower end of the cylinder and opening the latter to atmosphere whereupon lifting of the suction means and the sheet engaged thereby is eected, said Imeans also controlling the speed of upward movement of the suction means.

l0. In a sheet handling device of the type having a cylinder and .piston type suction means 5. In a sheet handling device ofthe type havin said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising means actuated by the vacuum created in the cylinder when a sheet seals the suction means for closing the connection between the vacuum supply and the lower end of the 'cylinder and opening the latter to atmosphere and for controlling the speed of upward movement of said suction means whereupon lifting of the latter and the sheet engaged thereby is eifected and at a desired speed.

11. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated' to engage and lift a sheet: the improvement comprising a valv controlled by the sheet sealing the suction means and movable in one direction for closing the connection between the vacuum supply and the lower end of the cylinder and opening the latter to atmosphere whereupon the piston lifts said suction means and the sheet -to be connected with a source of vacuum which latter is connected to and disconnected from the device at desired intervals, and a second connection between the other end of the cylinder and the vacuum inlet port aforesaid: the improvement comprising valve means in the second connection and controlled by the vacuum created in the suction means'and the end of they cylinder connected therewith when a sheet seals the suction means for disconnecting the second connection from the vacuum port and opening said other end of the cylinder to atmosphere, said valve means returning to its normal position upon release of the vacuum.

13. In a sheet handling device adapted to engage and move a sheet and having a cylindena piston reciprocal therein, a piston stem, suction means upon the end of the piston stem and connected with the upperend of the cylinder, a restricted connection betweenthe upper end of the cylinder and a vacuum inlet port adapted to be connected with a source of vacuum which latter is connected to and disconnected from the device at desired intervals, and a second connection between the lower end of the cylinder and the source of vacuum: the improvement comprising valve means in the second connection and controlled by the vacuum created in the suction means and upper end of the cylinder when a sheet seals the suction means for disconnecting the second connection from the vacuum source and opening the lower end of the cylinder to atmosphere; and means to restore said valve means to its normal position upon release of the vacuum.

14. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising a valve controlled by the sheet sealing the suction means and movable in one direction when vacuum is created upon one yside thereof for closing the connection between thevacuum supply and the lower end ofthe cylinder and opening the latter to atmosphere whereupon the piston lifts said suction means and the sheet engaged thereby; and .a spring for moving' said valve in the opposite direction upon release of vacuum to normally close the cylinder to atmosphere and enable another operation of said suction means.

15. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising a cap on the upper end of the cylinder having a relief port therein opening outwardly to atmosphere through one side thereof and two spaced ports for establishing communication between a source of vacuum and the upper and lower ends of said cylinder respectively; and a ported valve in said cap normally closing the relief port therein and enabling creation of vacuum in the cylinder through said spaced ports,

said valve being actuated by vacuum upon sealing of the suction means by the sheet to close the connection between the source of vacuum and the lower end of the cylinder and to open the relief port and connect the latter with one 0f the spaced ports whereby the lower end of the cylinder is opened to atmosphere whereupon lifting 0f the suction means and the sheet engaged thereby takes place.

16. In a sheet handling deviceof the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprislng a cap on the upper end of the cylinder having a relief port therein opening outwardly to atmosphere through one side thereof and two spaced ports for establishing communication between a source of vacuum and the upper and lower ends of said cylinder respectively; a ported valve in said cap normally closing the relief port therein and enabling creation of vacuum in the cylinder through said spaced ports, said valve being actuated in one direction by vacuum upon sealing of the/suction means by the sheet to close the connection between the source of vacuum and the lower end of the cylinder and to open the relief port and connect the latter with one of the spaced ports whereby the lower end of the cylinder is opened to atmosphere whereupon lifting of the suction means and the sheet engaged thereby takes place; and a spring for moving the valve in the opposite direction to close the relief port and enable operation of the suction means.

17. In a sheet handling` device of the type having acylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising a cap on the upper end of the cylinder' having a relief port therein opening outwardly to atmosphere through one side thereof and two spaced ports for establishing communication between a source of vacuum and the upper and. lower ends of said cylinder respectively; a ported valve in said cap normally closing the relief port therein and enabling creation of vacuumv in the cylinder through said spaced ports, said valve being actuated by vacuum upon sealing of the suction means by the sheet away from the relief port and beyond one of the spaced ports to connect said ports and open the lower end of the cylinder to atmosphere whereupon lifting of the suction means and the sheet engaged thereby is effected; and an adjustable stop `member for varying the movement of the valve and opening of the cylinder to atmosphere to control the speed of upward movement of the suction means.

18. In a sheet handling device of the type having a cylinder and piston type suction means in said cylinder which is vacuum reciprocated to engage and lift a sheet: the improvement comprising a cap on the upper end of the cylinder having a relief port therein opening outwardly to atmosphere through one side thereof and two spaced ports for establishing communication between a source of vacuum and the upper and lower ends of said cylinder respectively; a ported valve in said cap normally closing the relief port therein and enabling creation of vacuum in the cylinder through said spaced ports, said valve being actuated in one direction by vacuum upon closing of the suction means by the sheet away from the relief port 4and beyond one of the 1 sheet engaged thereby is effected; an adjustable stop member for varying the movement of the valve and opening of the cylinder to atmosphere to control the speed of upward movement of the suction means ;A and a spring for moving the valve in the opposite direction to close the relief port and enable operation of the suction means.

19. A valve means for connection with a sheet handling device adapted to engage and move a sheet and having a cylinder, a piston reciprocal therein, and suction means carried by the piston comprising a valve housing having a vacuum inlet port, an open port adapted to be connected to one end of the cylinder, and a relief port opening to atmosphere; a restricted connection extending from the vacuum inlet port and adapted to be connected with the other end of the cylinder; and valve means in the housing normally connecting the vacuum inlet port with the open port, the valve means being operable to disconnect the vacuum inlet port from the open port and connect the open port with the relief port when vacuum is created in the suction means when a sheet seals Vthe same, said valve means returning to its normal position upon release oi' the vacuum.

2o. A valve means for connection with a sheet handling device adapted to engage and move a sheet and having a cylinder, a piston reciprocal therein, and suction means carried by the piston comprising a valve housing having a vacuum inlet port, an open port adapted to be connected to one end ofthe cylinder, a second port adapted to be connected with the other end of the cylinder, and a relief port opening to atmosphere; and valve means in the housing normally connecting the vacuum inlet port with the open port and operable to disconnect the same and connect the open port with the relief port when vacuum is created in the suction means upon a sheet sealing the same, the valve means having a restricted load in an upper position.

port connecting the vacuum inlet port with the second port, said valve means returning to its normal position upon release of the vacuum.

21. A suction head in a transfer mechanism of the class described, having a vacuum cup adapted to be moved into engagement with articles to be lifted serially, a fluid pressure device to raise and lower said suction head with and without the load, and means acting to govern the lifting oper. ation under control of said'vacuum cup, whereby said vacuum cup is adapted to accommodate itself to engagement with articles of different di mensions, and each lifting operation supervenes only upon completion of a vacuum sealed joint between said cup and the load adequate to enable said cup to sustain the load.

22. In a transfer mechanism having a iiuid pressure cylinder provided with a piston and spaces above and below said piston adapted to be connected through suitable ductswith a source of suction; and a pneumatic automatic valve mounted movably in a valve chamber associated structurally with said cylinder, and adapted to move in a pneumatic control circuit for regulating connections between said ducts and the cylinder spaces, said valve being movable lto a position in which it shuts oil suction from the space below said piston while maintaining above said piston adequate suction to hold the same at an elevated position; and a plunger, suction head and load sustained by said piston.

23. A cylinder with a pneumatic automatic con'- -,tro1 valve having the features claimed in claim 22 wherein said valve is adapted to cause the admission of atmospheric pressure in the space below said piston, thereby to aid in holding the LEONARD BAKER. LEO C. WILLIAMS.