US1956647A - Attachment for pneumatic feed printing presses - Google Patents

Description

May 1, 1934. H. T. MccoY ATTACHMENT FOR PNEUMATIC FEED PRINTING PRESSES Filed July l1. 1932 2 Sheets-Sheet l Inventor mg/ YjYcCQy A ttomeys May 1,119.34. H, T, McCOY 1,956,647

ATTACHMENT FOR PNEUMATIC FEED PRINTING PRESSES Filed July 11, 1952 2 sheets-sheet 2 6) 1,/ .fz l

/ k W l Inventor Hzzzy Y/VcCgy I l I )ZZ/y' WOW/wg Attorneys Patented May l, 193% erster ATTACHMENT FOR PNEUMATIC FEED PRENTINC.- PRESSES e Claims.

ri-his invention relates to attachments for printing presses and particularly small job presses employing a suction shoe on a movable feeder arm for picking up a single sheet of paper stock from a stack and feeding it to the press.

Pneumatic or suction feed presses of this type are in general use throughout the world and are very satisfactory for some classes of printing. However, it has been found that when printing from a type set-up of large black letters or from plates having a large expanse of solid inlring surface, insucient ink is applied to the printing surface in the normal operation of the press. Operators have,lin such instances, been forced to manually control the press to cause it to feed a sheet of stock only every other printing cycle, thus permitting the inking rollers to pass over the printing face twice for each sheet printed and thereby properly distribute sufficient ink to the printing surfaces for satisfactory results. The method is open to the objection that it requires the constant attention of an operator to manually trip the machine whereby it prints only on alternate cycles of operation.

A broad object of the present invention is to provide an attachment for machines of the type described, which attachment automatically trips the feeding mechanism on alternate cycles and thereby makes the press function completely automatically.

As has been previously indicated, presses of the type to which this invention relates employ a suction shoe energized by a vacuum pump for lifting the top sheet from a stack of stock and feeding it to the press. A suction line containing an automatic valve mechanism connects the feeder shoe to the vacuum pump, the automatic valve opening and closing at such times in the cycle of operation as to cause the shoe to grip a sheet on the stack of stock, carry the sheet into the press, and then release it in a desired position relative to the printing cylinder. The feeder shoe then returns to the stack to pick up another sheet in the same manner as just described. In accordance with the present invention, I prevent the feeder suction plate from picking up a sheet eX- cept on alternate cycles of operation, by inserting an auxiliary valve in the suction line and automatically closing this valve on alternate cycles by a mechanical movement operated by the normal movement of the feeder mechanism itself.

A full understanding of the invention and its mode of operation may be had from the following detailed description when read in connection with the accompanying drawings, in which:

(c1. zii- 56) Fig. 1 is a highly schematic diagram showing so much of the mechanism of a printing press as is necessary for an understanding of myinvention. Fig. 2 is an enlarged detailed View of the cylinder of the press shown in Fig. 1.

Fig. 3 is a pian View, partly in section, of my attachment, this view being taken in the plane I-III of Fig. 3.

Fig. e is a detailed plan view of a portion of my attachment in a different portion of the cycle of operation.

Fig. 5 is a plan view of a portion of the mechanism shown in Fig. 3 instill another phase of the cycle of operation.

Fig. 6 is a detailed vertical sectional view taken in the plane V-VI of Fig. 3.

Fig. 7 is a detailed vertical sectional View taken in the plane Vil- VII of Fig. 6.

Fig. 8 is a detailed vertical section View taken in the plane VH1- VIII of Fig. 3.

Referring to Fig. 1, a press'of the type to which my invention is applicable comprises a chase of type or a printing 'plate 1 and an inking plate 2 mounted on a frame 3 which is reciprocable vertically in guides 4 in a frame designated generally at 5. The frame 3 is reciprocated continually up and down during the operation of the press by a connecting rod 6 driven from a crank (not shown). An upper inking roller '7 is mounted in front of the frame 3 and a lower inizing roller 8 mounted therebelow. The inking roller Sis provided with a reservoir 9 containing ink, into which the roller dips.

In Fig. 1 the frame 3 is shown in its uppermost position, in which position the lower edge of the inking plate 2 is juxtapositioned to the inking roller 7. Upon downward movement of the frame 3, inlring roller 7 is first traversed by the inking plate 2 and then by the print'- ing plate 1, the upper edge of the area of printing plate 1 being juxtapositioned to the roller 7 in the lowermost position of the frame 3. As the inking plate 2 moves downwardly past roller 7, it comes in contact with the primary inking roller 8 and ink is transferred from the reservoir 9 onto the inking plate 2 by the roller S during this phase of the operation. On the succeeding upward movement of the frame 3, the inking plate 2 moves upwardly past roller 3, receiving additional ink during this process, and then moves upward past roller 7, transferring ink to roller Y during this operation. Ink is then transferred from the secondary inking roller 7 to the printing plate 1 as the latter moves downwardV and upward past roller 7.

Positioned slightly above the secondary inking roller 7 and juxtapositioned to the frame 3 is a printing cylinder designated generally at 10. The printing cylinder 10 comprises a padded surface 11 extending a little more than half way around its circumference, as shown, and is provided with a suction shoev12 along one edge of the surface 11 for gripping a sheet of stock 13 lying on a transfer table 14. The cylinder 10 is provided on one end with a gear 15 which meshes with a rack 16 secured to the frame 3.

Gear 15 is normally not attached to the cylinder 10; therefore as the frame 3 and the rack 16 reciprocate up and down, the gear 15 rotates but the cylinder 10 remains stationary. However, by a pneumatic interlock, the cylinder 10 is locked to the gear wheel 15 when a sheet of stock is fed to the transfer table 14. This interlock mechanism comprises a diaphragm chamber 17 (referring now to Fig. 2) having as one wall a flexible diaphragm 18 which is attached by a link 19 to a pawl 20, the end of which engages a ratchet 21 rigidly secured to a shaft 22, which, in turn, is secured to a pawl 23 positioned to engage in a notch 24 in the outer edge of a shoulder 25 on the gear wheel 15. The pawl 23 is normally rotated out of engagement with the notch 24 by a spring 26. The diaphragm chamber 17 is connected through a tube 27 to the suction shoe 12 and through a second tube 28 to a continuously operated vacuum pump, not shown.

When a sheet of stock 13 is deposited upon the transfer table 14, its innermost edge lies over the suction shoe 12 and prevents the admission of air therethrough. As a result, the aforementioned continuously operating vacuum pump exhausts the air from the diaphragm chamber 17 through the tube 28, thus forcing the diaphragm 18 to the left and rotating the ratchet 21, shaft 22 and pawl 23 in counterclockwise direction to engage the pawl 23 in the notch 24 in the gear 15. Thereafter as gear 15 is rotated in clockwise direction by downward movement of the rack 16, the cylinder 10 is rotated and the suction shoe 12 draws the sheet of stock 13 around the cylinder and into engagement with the printing plate 1 as the latter moves downward past the cylinder. After the sheet has been printed, as described, by contact with the printing plate 1, it is automatically discharged from the cylinder 10 but since the mechanism for this purpose is of no interest in connection with the present invention, it has not been shown.

It will be observed from the foregoing description that if sheets of stock are supplied to the transfer table 14 continuously, the cylinder 10 will rotate with the gear 15 upon each downward movement of the frame 3 and a sheet will be drawn about the cylinder 10 and printed during each cycle of operation of the frame 3.

Sheets are supplied to the transfer table 14 from a stack of stock 29 by a feeder mechanism comprising a feeder shoe 30 mounted for oscillatory movement upon a feeder arm 31. Feeder shoe 31 is normally oscillated from a position above the stack 29 to a position above theA transfer table 14 once during each cycle of operation of the printing cylinder 10, the arm 31 being mechanically coupled to the rest of the press mechanism by links, not shown. Feeder shoe 30, like the suction shoe l2, is provided with suction means for gripping the upper sheet of stack 29, the suction being produced by the vacuum pump previously mentioned, to which the feeder shoe 30 is connected by a hose 32 which extends from the shoe through hollow arm 31, through my automatic cut-off valve designated generally at 33, and thence to the vacuum pump through tube 34.

Assuming that the valve 33 between tubes 32 and 34 is always open, suction will be applied to the shoe 30 as it moves into position above stack 29, to grip the top sheet. This suction is maintained until the shoe 30 is moved to a point above the transfer table 14, when it is cut-off by a valve (not shown) to discharge the sheet onto the transfer table 14. Therefore, in normal operation of the press, the shoe 30 carries the upper sheet from stack 29 to the transfer table 14 during each cycle of operation of the cylinder 1G and the frame 3, thus feeding a sheet of paper through the press during each cycle of opera-tion of the frame 3.

In accordance with the present invention, the valve 33 is inserted in the suction line to feeder shoe 30 and closes upon alternate cycles of operation of the shoe 30 to cut off the suction to shoe 30 and thereby prevent it from gripping the top sheet of stack 29 and transferring it to the transfer table 14. Accordingly, when the valve 33 is closed and the feeder shoe 30 fails to transfer a sheet to the transfer table 14, the printing cylinder 10 remains stationary but the frame 3 on its downward and upward movement causes the transfer of ink from roller 7 to the printing plate l. Thus an additional inking operation is provided for each sheet printed.

The valve mechanism 33 and its operation wll now be described with reference to Figs. 3 to 8 inclusive, The valve proper comprises a member 35 containing a U-shaped passage 36 which is connected at opposite ends to hose 34 and 32 respec tively. Slidably mounted in member 35 for transverse movement is a gate 37 containing an aperture 38. Gate 37 ts snugly in the chamber 35 so that when moved to the position shown in Fig. 3, it effectively seals the passage 36. However, when moved to the position shown in Fig. 5, the aperture 38 is juxtaposltioned to the passage 36 and permits free passage of air therethrough.r

Member 35 is conveniently manufactured in two sections as shown in Fig. 6, these sections being secured together by screws 39 and secured to a base plate 40 by screws 41. The base plate 40 is secured to the frame 5 of the printing press by bolts 42.

Also attached to the plate 40 and positioned to one side of member 35 are two guide members 43, which slidably support a carriage 44. Carriage 44 is pivotally connected at one end by a link 45 to the feeder arm 31.

Thus a plate 46 (referring for the moment to Fig. 1) is bolted to the arm 3l and carries a pin 47 which passes through an aperture in the end of link 45. By virtue of the connecting link 45, the carriage 44 is reciprocated back and forth in guides 43 during each movement of the feeder arm 31.

Pivotally mounted for horizontal oscillation upon the top of carriage 44, is a cam plate 48 shaped as shown in Fig. 3; thus, it is relatively thick adjacent the pivot 49 and is provided with outwardly extending shoulders 50 and 51 respectively and a rearwardly projecting shoulder 52, whereas the opposite end is gradually tapered forwardly to a point 53. The outer end of the gate 37 is extended to a point substantially over the path of movement of the carriage 44 and is provided with a downwardly projecting cam-follower 54 which projects into the path of movemen of the cam plate 48. Secured to the upper face of the carriage 44, slightly in advance of the forward end 53 of cam plate 48, are two stationary cam plates 55 and 56, which project substantially the same distance above the carriage as does the oscillatable cani plate 48.

The operation of the device will now be dcscribed. Assuming that on the last movement of feeder shoe from stack 29 to the transfer table 14, the valve 33 was closed, the feeder shoe 30 did not transfer a sheet to the transfer table and the valve 33 will be in the position shown in Fig. 4, that is, the gate 37 will be in such a position as to throw Vthe aperture 38 out of alignment with t; e passage 36 and the oscillatable cam plate 48 'will have its tip 53 deflected toward the member 35. As the feeder arm 3l moves'back toward the stack 29, the carriage 44 will be reciprocated to the left by link 45. Therefore the tip 53 of cam plate 48 will pass to the left of cam-follower 54 (referring for the reference direction to Fig. 7), thus moving the cam-follower 54 and the gate 37 to the left until aperture 38 is juxtaposed to the passage 36, in which position the suction is applied through tube 34, valve 33 and tube 32 to the suction shoe 3), so that it grips the top sheet on stack 29 and on its subsequent feeding movement carries this sheet to the transfer table 14.

As the carriage 44 moves into its extreme left position, as shown in Fig. 5, the cam-follower 54 encounters the shoulder 50 on cam plate 48, and rotates the cam to throw the point 53 away from the member 35. Accordingly, on the subsequent rearward movement of carriage 44 with the feeder arm 3l, cam 48 is left in the position shown in Fig. 5 and cam-follower 54 and the gate 37 remain in their extreme left positions (referring again to Fig. 7 for direction reference). 'As carriage 44 moves to its extreme rearward position, the stationary cam plate 56 engages the camfollower 54 and shifts it slightly to the right but not far enough to move the aperture 18 out of registration with the passage 36. This movement of cam-follower 54 by cam plate 56 is sufficient, however, to cause the cam-follower 54 on the subsequent forward movement of carriage 44, to engage the opposite face of the cam plate 48 and be moved thereby into its extreme right position (with reference again to Fig. 7), in which the aperture 38 is out of registration with the passage 36. As carriage 48 completes its forward movement, the cam-follower 54 then engages with shoulder 51 on cam plate 48 and oscillates it back into its original position as shown in Fig. 3.

It will be apparent from the foregoing description that I have provided a valve mechanism which opens on one forward movement of the arm 31 and closes on the succeeding forward movement of this arm, so that during alternate feeder movements of arm 31 and feeder shoe 30, suction is applied to shoe 30 to feed a sheet to the transfer table 14, and on the intervening alternate cycles, suction to shoe 30 is cut off by valve 33 so that no sheet is transferred. As a result, I provide a mechanism for attachment to a pneumatic feed press which will automatically cause the press to print only on alternate cycles of operation while inking on every cycle.

In the claims I have specified a pneumaticfeed printing press and it is to be understood that I refer to a press in which sheets of stock are transferred one at a time from a stack to the printing mechanism, by a feeder mechanism having asuction feeder shoe connected through a suction line with a vacuum pump, the feeder shoe moving periodically to carry a sheet from the stack to the printing mechanism and the suction line containing a valve that is automatically periodically opened and closed during each cycle to cause the feeder shoe to pick up a sheet from the stack and subsequently discharge itinto the press. o

I claim: f v

l. An attachment for a pneumatic-feed printing press comprising a valve insertable in the feeder shoe suction line of the press, and means operable by movement of the feeder shoe for closing said valve during alternate feeding movements of said shoe and opening said valve during the intervening feeding movements whereby f the feeder shoe feeds a sheet only on alternate feeding movements, said valve comprising a member having a passage therethrough insertable into said suction line, a gate reciprocable between two positions to open and close said passage, a carriage, guides slidably supporting said carriage for movement laterally with respect to the path ofY reciprocation of said gate, means for linking said carriage to the feeder shoe of the press whereby it reciprocates in unison with the feeder shoe, an oscillatable cam plate pivotally mounted upon said carriage, said plate being relatively wide at its pivotal mounting and diminishing in width away from said pivotal mounting to a narrow end, means for limiting oscillation of the narrow end of said cam plate to equal arcs on either side of the path of movement of said pivot, a cam-follower on said gate engageable with one side of said cam plate as the latter is moved in one direction by movement of said carriage, whereby said gate is moved into its opposite position, and a shoulder on said cam plate engaging with said cam-follower near the end of the stroke to oscillate said cam plate into its opposite position, whereby on the next succeeding stroke in the same direction, the cam-follower encounters the opposite side of said cam plate and is thereby moved, together with said valve gate, into its opposite p0- sition.

2. An automatic cut-olf valve for insertion in the feeder shoe suction line of a pneumatic-feed printing press for cutting off suction to the feeder shoe on alternate cycles of operation, comprising a carriage mounted in guides for reciprocable movement and adapted to be linked to the feeder arm of the press, whereby it reciprocates in unison with the feeder arm, a cam plate pivotally attached to said carriage and having laterally opposed cam faces spaced apart adjacent said pivot point and tapering to a common point at the forward end, means on said carriage engageable with portions of said cam plate for limiting lateral movement of the forward end of the plate in each direction to two extreme positions, in each of which one of said respective cam faces is substantially parallel to the path of movement of said carriage, a valve having an actuating member laterally movable with respect to the path of movement of said cam and comprising a camfollower in the path of movement of said cam plate, whereby upon forward movement of said carriage, said cam-follower is engaged by one of said cam faces and shifted laterally to open said cam face is parallel with the path of movement of said carriage, and means on said carriage ahead of the forward end of said cam plate for shifting said cam-follower slightly away from the extreme position into which it was last moved by said cam plate, whereby on the succeeding forward movement of said carriage, said cam-follower is engaged by the opposite cam face and shifted by the latter into its other extreme position.

3. In an attachment for a pneumatic-feed printing press, an air valve insertable in the feeder shoe suction line of the press, a cam follower secured to said valve for opening and closing the valve, a cam reciprocable longitudinally between two positions, a portion of said cam being movable laterally Awhereby upon reciprocation of said cam in one laterally deflected position it contacts said cam follower with one cam face and moves said cam follower into one position, and upon reciprocation with said cam in the opposite deflected position it contacts said cam follower with a different cam face and moves the follower into its original position, and means for deflecting said cam into its opposite lateral position at the completion of each reciprocation.

4. An attachment for a printing press having an oscillating feeding arm and a suction feed mechanism on the arm, said attachment comprising a longitudinal reciprocable carriage, a cam having two converging cam faces and mounted for lateral movement on said carriage, means for limiting lateral movement of said cam, a cam follower slidably supported for lateral movement with respect to the path of movement of said carriage and positioned to intercept one or the other of said two converging cam faces, a pair of shoulders on said cam adapted to be alternately contacted by said cam follower on alternate movement of said carraige to shift said cam from one lateral position to the other, whereby said cam follower is shifted laterally in opposite directions on successive strokes of said carriage, a valve connected to said cam follower for closing and opening the feeder shoe suction line of the press in the respective extreme positions of movement of said cam follower, and means for linking said carriage to the oscillating feeder shoe mechanism of the press for movement in synchronism therewith.

HENRY T. MCCOY.

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