US3731623A

US3731623A - Glider press

Info

Publication number: US3731623A
Application number: US00083800A
Authority: US
Inventors: H Bubley; C Oltra
Original assignee: American Screen Printing Equipment Co
Current assignee: American Screen Printing Equipment Co
Priority date: 1970-10-26
Filing date: 1970-10-26
Publication date: 1973-05-08
Anticipated expiration: 1990-05-08

Abstract

A stencil screen printing press is illustrated having a peeling means which elevates the screen from the surface being printed immediately behind the squeegee for ''''off-contact'''' printing. The peeling means elevates the screen faster when the squeegee is at the center of the screen than when the squeegee is at either end to compensate for stretching of the fabric. A novel registration means operating in conjunction with the peeling means is also illustrated. A simplified mechanical drive arrangement permits the press to be of universal design, allowing it to be scaled up or down in width and length to any desired size. A novel carriage assembly to support the squeegee and flood bar is also shown, having a captivated cam arrangement which shifts the squeegee and flood bar at the end of the stroke. Quick change from flood to non-flood condition is also provided.

Description

[ 51 May 8, 1973 [54] GLIDER PRESS [75] Inventors: Henry J. Bubley, Deerfield; Claude 11. Ohm, Chicago, both of 111.

[73] Assignee: American Screen Process Equipment Company, Chicago, Ill.

[22] Filed: Oct. 26, 1970 [21] Appl. No.: 83,800

[52] US. Cl. ..101/114, 101/123 [51] Int. Cl. ..B4li 15/00 [58] Field of Search ..101/114, 121-124,

[56] References Cited UNITED STATES PATENTS 1,102,884 7/1914 Delevil ..101/114 1,898,406 2/1933 Tate et al.. ..l0l/l23 2,018,989 10/1935 Wulf ..101/123 X 2,581,775 l/l952 Wade ..101/123 2,704,510 3/1955 Walsh, Jr... ..101/126 X 2,936,705 5/1960 I-Iall ..101/123 2,963,964 12/1960 Klump... ..101/126 X 2,975,705 3/1961 Gilman...... ..101/123 3,101,665 8/1963 Hall ..101/123 3,166,011 1/1965 Landesman.. ..l0l/l23 3,263,603 8/1966 Fuchs ..101/123 FOREIGN PATENTS OR APPLICATIONS 702,297 3/1966 Italy ..101/123 702,298 3/1966 Italy ..101/123 1,207,836 2/1960 France ..lOl/123 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Eugene l-I. Eickholt Attorney-Robert E. Wagner 5 7 ABSTRACT A stencil screen printing press is illustrated having a peeling means which elevates the screen from the surface being printed immediately behind the squeegee for off-contact printing. The peeling means elevates the screen faster when the squeegee is at the center of the screen than when the squeegee is at either end to compensate for stretching of the fabric. A novel registration means operating in conjunction with the peeling means is also illustrated. A simplified mechanical drive arrangement permits the press to be of universal design, allowing it to be scaled up or down in width and length to any desired size. A novel carriage assembly to support the squeegee and flood bar is also shown, having a captivated cam arrangement which shifts the squeegee and flood bar at the end of the stroke. Quick change from flood to non-flood condition is also provided.

20 Claims, 13 Drawing Figures PATENTEURAY' 81m 3.731.623

SHEET 1 OF 4 INVENTORS HENRY J. BUBLEY CLAUDE H. OLTRA BY ATT'Y PATENTEDHAY' 8191s SHEET 2 OF 4 I INVENTORS HENRY J. BUBLEY CLAUDE H. OLTRA W ATT'Y.

PATENTEDHAY 8W 3.731.623

SHEU H []F 4 ll'lh IN VENTORS HENRY J. BUBLEY CL AUDE H OLTRA ATT'Y.

GLIDER PRESS This invention relates to stencil screen printing apparatus in general and, more specifically, to a new and improved stencil screen printer having various novel features which improve its performance and promote economy in manufacture.

In known types of stencil screen printing apparatus, the screen frame is raised and lowered to permit insertion and removal of the stock to be printed. In many instances, this may be a paper sheet, piece of hardboard, plywood or the like. When the stencil screen is in the lowered position, a squeegee is pushed over the stencil screen to force ink through the screen and onto the sheet to print the intelligence pattern formed on the screen. After the print stroke, the squeegee is raised and a flood bar is lowered into engagement with the screen to push the ink across the screen to the starting point of the print stroke. During the return, the screen is in the elevated condition to permit the printed stock to be removed and an unprinted piece inserted.

In some printing techniques, the flood bar and squeegee cooperate with each other in a non-flood" condition to form a carrier to carry the ink pool to the starting point of the printing stroke where the squeegee alone will force it through the stencil screen to perform the printing function.

It is highly desirable, especially inthe larger screen sizes, to have the screen elevated or peeled away from the work immediately behind the squeegee without permanently distorting the screen in order to obtain the sharpest print. This is referred to in the trade as offcontact printing. In the past, this has been accomplished through a spring mechanism which exerted a constant upward force on the chase or screen frame with some means such as a roller or the like acting in opposition on the chase or screen frame to positively hold the screen frame in the down position. The roller moved along with the squeegee, permitting the screen to be elevated at a uniform rate. This technique left something to be desired when consideration is given to the fidelity of the resulting print.

It has now been found that the best results in off-contact printing can be obtained by having the peeling mechanism positively actuated with resistance to the elevating force supplied solely by the squeegee. Through the novel peeling mechanism of the present invention, the rate of peeling follows a harmonic motion pattern in that it peels faster at the center of the screen that at either end, thereby compensating for the natural tendency of the screen material to stretch. This assures that the print will be sharp in all areas printed.

A novel carriage assembly is provided having a novel shuttle mechanism with captivated cams to shift the squeegee and flood bar from the print condition to the flood condition on the return stroke. The carriage assembly also includes a novel change-over arrangement which permits the rapid conversion from the conventional flood bar arrangement to a non-flood scoop. This is accomplished by shifting a pivot pin in each of the carriage assemblies and substituting a non-flood scoop for a flood bar. t i

The present invention is a simplified design providing a novel adjustment which allows the print stroke to be varied, The print stroke is always initiated at the front of the press and the length of stroke determined by a simple adjustment on the drive mechanism. Moreover, in conjunction with the novel peeling means described above, a unique guide is provided which assures accurate registration on each printing stroke even in offcontact printing.

Because of the simplicity of the novel design, the press may be scaled up or down, depending upon requirements, with the general basic design used for both large and small press sizes. Only the strength of the materials utilized limits the maximum size of the press. This feature is derived as a result of the location of the drive arms outside the drive frame but inside the chase and bed. The unique drive arrangement is also located so that the bed and chase on any given press may be scaled up or down since there is nothing to prevent either from being increased or decreased in over-all size. Moreover, the underside of the bed is free of obstruction, permitting the use of mechanical-type feeds such as a vacuum belt feed and takeoff as is described in co-pending application Ser. No. 49,828, filed June 25, 1970 and entitled Vacuum Belt". Other advantages of the novel press design will become apparent upon consideration of the objects and following description.

It is a principal object of this invention to provide a new and improved printing press of the stencil screen type.

It is a further object of this invention to provide a new and improved printing press having a novel peeling means which elevates the screen from the surface being printed immediately behind the squeegee.

It is a still further object of this invention to provide a stencil screen printing press having a novel peeling means which peels at a faster rate at the center of the screen than at either the forward or rearward ends.

It is a still further object of this invention to provide a new and improved stencil screen printing press having a novel peeling means and guide means which functions to assure accurate registration.

It is a still further object of this invention to provide a stencil screen printing press of uncomplicated design having a novel drive arrangement permitting the press to be manufactured in various sizes through merely increasing the size of the components.

It is a still further object of this invention to provide a stencil screen printing press having novel carriage assemblies supporting the squeegee and flood bar, said carriage assemblies including a unique shuttle arrangement which permits the rapid conversion from flood to non-flood.

It is a still further object of this invention to provide a stencil screen printing press including un'ique carriage assemblies to support the squeegee and flood bar, which carriage assemblies include captivated cams to shift the flood bar and squeegee in timed relation to the press movement.

Other objects and advantages of the present invention will become apparent upon consideration of the accompanying drawings and attendant description.

IN THE DRAWINGS FIG. 1 is a perspective view of the printing press of the present invention;

FIG. 2 is an enlarged fragmentary side elevation of the printing press shown in FIG. 1 with the screen in the lowered or printing position;

FIG. 3 is a front elevational view of the press shown in FIG. 2 with the carriage assembly omitted for clarity and parts broken away to show the registration pins;

FIG. 4 is a schematic side elevational view of the press shown in FIGS. 1-3 with dotted lines to show the position of the drive arms at the end of the printing stroke;

FIGS. 5A, 5B and 5C are schematic side elevational views to illustrate the operation of the novel peeling arrangement in relation to squeegee movement during off-contact printing;

FIG. 6 is a rear elevational view of the press shown in FIGS. 1-4 with the screen in the down or print position;

FIG. 7 is a top plan view of the squeegee and flood bar carriage assembly with the support arms shown fragmentarily;

FIG. 8 is a side elevational view of the carriage assembly taken along the line 8-8 of FIG. 7 with the squeegee and flood bar in the condition assumed during the printing stroke;

FIG. 9 is a view similar to FIG. 8 with the carriage assembly in the position assumed on the return stroke;

FIG. 10 is a view similar to FIG. 9 with a non-flood scoop attached and the carriage assembly converted to the non-flood scoop condition; and

FIG. 11 is a graph to illustrate the rate of elevation of the screen of the present invention contrasted with one of known prior art type.

Referring now to FIG. 1, reference character 10 generally indicates the improved press of the present invention. The press 10 includes a frame 11 having an operating console 12 located at the lower front which permits the operator to control the operation of the press. A drive housing 13 is disposed at the rear of the frame 11 and houses the motor and drive elements which will be described in greater detail hereinafter with respect to FIG. 6.

A printing bed 14 is.located on the top of the frame 11 and may be of any suitable type with or without vacuum means to hold the stock to be printed during the printing operation. In the preferred form of the invention, the bed 14 consists of a vacuum base of the type described in US. Pat. No. 3,429,544 to Williams, issued Feb. 25, 1969 for AIR TABLE. Vacuum to the base is supplied through a flexible tube l5joined to a vacuum source indicated generally at 16 and supported on the frame 11 in the drive housing 13. The air flow through the tube may be reversed to provide a blow-back release of the stock being printedv Because of the unique drive arrangement, this sequence is easily selected or modified.

A screen press printing head is indicated generally at 20 and is disposed for pivoting movement away from and toward the press bed 14 in a manner well known. When the printing head 20 is in the condition shown in FIG. 1, the stock previously printed may be removed and unprinted stock inserted. Such stock may be ofany desired type such as paper, cardboard, hardboard, plywood, cloth or the like.

A pair of

arms

21 and 22 serve to support a screen assembly indicated generally at 23. The screen assembly 23 consists ofa master frame or chase 24 which serves to mount a stencil screen 25 of known type. The stencil screen consists of frame and screen fabric which may be formed of polyester, nylon, stainless steel or the like. The stencil screen 25 is held in the chase 24 by clamps 26 or the equivalent acting against its frame. These are chosen to facilitate ease in replacement of the screen.

As seen in FIG. 2, the master chase 24 is pivoted as indicated at 27 to permit movement relative to

arms

22 and 23. The chase 24 is supported beneath

arms

22 and 23 for movement relative to the arms in a manner to be described hereinafter.

The

arms

22 and 23 are formed from box-like or hollow members which are supported at the rear of the press for pivoting movement on opposite ends of a shaft 28 received in

bearings

30 and 31 on opposite sides of the frame. A transverse brace 32 also connects the arms at their rearward portions to provide the requisite rigidity. At the forward end of the arms are provided

vertical braces

33 and 34 which are joined at their lower ends by a transverse brace or head tie bar 35 to provide lateral rigidity.

As best seen in FIG. 3, the head tie bar 35 has a vertical guide 36 attached for positioning between pairs of rollers 37 and 38 which are mounted on the master chase. This assures that the chase will be guided in its vertical movement during the peeling operation which will be described in greater detail hereinafter.

As seen in the right-hand portion of FIG. 3, at the lower end of the brace 33 is a frusto conical opening 18 to receive the frusto conical pin 19 carried on the frame 11. A similar pin 19' is received in the brace 32. This assures that the forward part of the

arms

22 and 23 will be properly positioned before the printing stroke commences and will maintain registration throughout the stroke.

Disposed on each of the

arms

22 and 23 is a carriage assembly of the type shown at 40 in FIG. 2 and 41 in FIG. 7. The

carriage assemblies

40 and 41 are of identical but reverse construction, one being a mirror image of the other. In the interest of brevity, specific description will be limited to the carriage assembly 41 which is mounted on the arm 23 and shown in greater detail in FIGS. 7-10.

In FIGS. 7-10, the carriage assembly 41 is illustrated in various modes of operation. As can be seen, the carriage assembly 41 is carried on the arms 23 and includes a housing 42 which has a U-shaped portion closed off by a side plate 43 bolted or attached by equivalent means to the U-shaped portion. Nylon pads or guides (not shown) are provided within the housing 42 to assure smooth and friction-free movement of the carriage along the arm 23 although lateral forces are minimal in operation. A brake pad 160 of nylon or the equivalent is located between the top of the respective arm and housing supporting the ends of the squeegee. A set screw 161 permits adjustment of the spring force applied to the pad 160 to whatever degree is desired. A. pair of

rods

44 and 45 join the

carriage assemblies

40 and 41 to assure unitary movement.

Ashuttle 46 is interposed between the side plate 43 and the outer surface of the arm 23. The shuttle 46 is held captive in the carriage housing 42 and is provided with a pair of oppositely-directed cam tracks 50 and 51 which are mirror images of each other and function to shift the flood bar and squeegee, respectively. Due to the resistance to movement by the brake pad 160, the shuttle is assured of being actuated with each change in direction of movement.

On the outside of the housing 42 is a scissors-type squeegee and flood bar support which includes a squeegee supporting lever 52 mounted to pivot about a bearing bolt 53 threaded into the carriage housing 42. The opposite end of the lever 52 contains a cam follower 54 extending through an opening in the plate 43 into the cam track 51. The cam follower may be a roller bearing or the like and is held captive in the cam tracks 51 functioning to move the arms 52 about the pivot 53 in response to linear movement of the shuttle 46. Quieter operation of the shuttle is achieved by driving the squeegee and flood bar from the shuttle 46 directly. An elongated slot 164 is formed in the shuttle 46 (FIGS. 8-10) and a nylon roller 165 is positioned in the slot and supported by the plate 43. Thus, the driving force is transmitted directly from the shuttle 46 to the plate 43, reducing noise and avoiding wear on the cam tracks 50 and 51 and their respective followers.

The squeegee support lever 52 is provided with a squeegee assembly supported by a threaded rod 61 bolted or attached to a flange 62 formed on the lower end of the support arm 52. A squeegee clamp 63 is carried at the lower end of the threaded rod 61 to removably mount a squeegee 64 of conventional design.

A second lever is pivotally mounted by a bearing bolt 71 fastened into the squeegee support lever 52 and forms the support for the flood bar. A threaded rod 73 is attached at one end to a flange 74 on the lower end of the lever 70, while the opposite end supports an L- shaped bracket 75 for mounting a flood bar 76 of conventional design. A cam follower 77, identical to the cam follower 54 on the lever 52, is carried on the end of the lever 70 and extends through an opening in the plate 43 into the cam track 50. As is evident from the foregoing description, reciprocation of the shuttle 46 in a linear direction lifts the squeegee and lowers the flood bar and vice versa with a scissors-type action.

The shuttle 46 is driven in its linear movement by a connecting rod 80 joined at its opposite end to a drive arm 83 mounted on a main drive shaft (FIG. 6). A drive arm 82 of the same generally L-shaped configuration as the drive arm 83 is mounted for angular movement on the opposite end of the main drive shaft 85. As seen in FIGS. 1 and 2, the drive arm 82 drives the shuttle of the carriage assembly 40 through a drive rod 84 identical to drive rod 80. While a drive rod is shown, it is contemplated that a cable, chain or other drive means may be used, depending on the final press configuration.

The press drive arrangement is best illustrated in FIGS. 4 and 6 and includes a motor mounted on a movable motor support 101. A threaded shaft 106 cooperates with threads in the motor support and permits adjustment of the motor 100 relative to the frame 1 1. Suitable guides are provided to assure proper movement of the motor 100 during speed adjustment. If desired, a mechanical drive arrangement such as a chain or worm drive may be provided to permit adjustment of the press speed by the operator while standing at the console.

A variable speed drive pulley 102 is mounted on the motor 100 and through a belt 103 drives a pulley 104 mounted on the input shaft 109 of a reduction gear arrangement located in the housing 105. The reduction gear arrangement is of known type having an output shaft 106 disposed at right angles to the input shaft 109 and extending from opposite sides of the reduction gear housing 105. On one end of the output shaft 106 is a main drive arm 110 while on the opposite end is a press lift cam 108 and a plurality of

cams

111, 112 and 113 which cooperate with

switches

114, 115 and 116. Cams 111-113 are angularly adjustable on the shaft 106 to time the actuation of the cooperating switches 1 14-1 16 to perform various functions in the printing cycle, e.g., energize the vacuum bed, apply the blow-back and energize the vacuum take-off. Obviously, additional switches can be provided for any other accessories which might be added to the press. Timing of the switch operation is easily adjusted because of the convenient location of the drive unit, permitting the relationship to the lifting cam 108 to be visually observed.

The press drive arm 110 is connected through a second arm to an arm 121 which is generally L- shaped, having the arm 122 joined to the shaft 85. The drive arm 121 is provided with an arcuate slot 123 which permits the rod 122 to be angularly adjusted, thereby selecting the length of stroke of the press. The arm 120 moves through approximately 90, imparting movement to the shaft 85 which, in turn, moves the

arms

82 and 83 and drives the

carriage assemblies

40 and 41 in a manner to be described more fully in connection with the description of the operation of the press.

As seen in FIG. 2, the press lift cam 108 cooperates with a follower which is rigidly connected by arm 131 to the brace 32 across the rear of the

press arms

22 and 23. When the high side of the cam 108 is engaged with the follower 130, the arm 131 is moved down, elevating the press head to the condition shown in FIG. 1. When the low side of the cam 108 engages the follower 130, the weight of the press head 20 causes it to be lowered to the print position shown in FIGS. 2-4. The dwell of the press in either condition is easily built into the cam design to permit it to remain a certain percentage of a full cycle in the elevated and lowered positions. The actual duration of dwell in any cycle may be adjusted by speeding up or slowing down the press through moving the motor 100 on the guides which automatically adjusts variable pulley 102 and is limited only by the speed with which Stock to be printed can be placed on the bed and removed after printing is complete.

As seen in FIGS. 2-4, the novel design of the drive for the press permits it to be located within the sides of the bed 14 and chase 24 (FIG. 3). This drive arrangement allows stroke length to be shortened from the rear of the press toward the front assuring that no appreciable movementof the squeegee will occur when the press head 20 is elevated. As best seen in FIG. 2, the bed 14 is unobstructed by the

drive arms

82 and 83 when the squeegee is in position to start the printing stroke. This arrangement permits mechanical feeds, conveyors and the like to be used with the press or the press used as an adjunct to an existing conveyor line.

As described briefly above, all of the drive elements are located at the rear of the press to provide smooth operation, simplify the design, minimize cost, maximize ease of servicing and permit the press to be scaled up or down with no appreciable change in the press drive required. In part, these advantages are attributable to mechanical drive arrangement as is best shown in FIG. 4. The axis about which the press head pivots is coextensive with the geometric axis of the shaft 28. The drive arm axis is coextensive with the geometric axis of the shaft 85. These two axes are located in vertical alignment with the drive shaft of the gear box disposed below the upper axis and above the lower axis and the axes forming a triangular pattern. The press stroke can be shortened or lengthened by moving the end of the arm 120 in the slot 123 and the

carriage assemblies

40 and 41 will remain substantially fixed relative to the

arms

21 and 22 when the press head 20 is elevated. As is evident, movement of the

carriage assemblies

40 and 41 relative to the

arms

21 and 22 when the press head is elevated is undesirable because of the possible damage to the work through ink splatter, dropping, smearing or the like.

The peeling arrangement can be seen in FIGS. 4 and 6 and is identified generally by

references

140 and 141. The peeling arrangement is identical on each side of the press and, therefore, specific description will b limited to that shown in FIG. 6.

A cable 142 is connected as at 143 to the master chase 24. Quickly releasable connections are provided to permit the press arms to be elevated independently of the chase, thereby facilitating screen insertion and removal. In this condition, the squeegee and flood bars may also be removed for cleaning and the like without affecting their adjustment. The cable 142 extends over a pulley 144 which is housed within the front of the press arm 23 and through the press arm 23 and over a pulley 145 located at the rear of the press arm 23. The cable terminates at a turnbuckle assembly 146 after having been wrapped slightly more than 90 around the pulley 145.

The turnbuckle assembly is of known type andv is connected through an arm 147 to a collar 148 which is mounted for rotation with the shaft 85 and serves to permit easy adjustment of the tension on the cable. When the press is in the down position and the

carriage assemblies

40 and 41 are located at the initiation of the printing stroke, the collar I48 and connecting link 147 are in the condition shown. As the shaft 85 rotates in response to movement of the arm 110, a pulling force is exerted on the cable, lifting the master chase 24 in opposition to the downward pressure exerted by the squeegee 64 on the screen S.

The sequence of events is illustrated in FIGS. A, 5B and 5C, demonstrating the various conditions of peeling of the screen S in the master chase 24 in schematic form with the degree of peel exaggerated. In FIG. 5A, the carriage assembly 41 has just commenced its rearward movement, at which time the elevation of the master chase 24 is progressing at a fairly slow rate. As the carriage assembly 41 approaches the mid-position shown in FIG. 5B, the master chase 24 is being elevated at a faster rate. As the squeegee approaches the rear or end of the print stroke, the master chase 24 assumes the general condition shown in FIG. 5C and the rate of elevation is decreasing.

The peeling function during off-contact printing is according to harmonic pattern which is graphically demonstrated in FIG. 11 where A represents the peeling curve of a known type of press with curve B representing the curve of peeling of the press of the present invention. The ordinate of the graph is when screen lift or rise is plotted against squeegee movement for a full cycle. This is highly desirable because it is in the central region of the screen that the most stretch is experienced regardless of the tension on the screen, while little or no stretch is experienced in the final stages of the print stroke. Moreover, the pressure can be kept quite uniform because the sole opposition to the elevating movement is provided by the flexibility of the squeegee. Accordingly, off-contact printing producing an excellent finished product is possible through the present design.

If the operator does not desire off-contact printing, he can loosen the cables at their rearward ends by the tum-buckles provided with very little effort. It is to be appreciated that off-contact printing may not be necessary when the screen material does not have any appreciable stretch and, thus, the peeling function would become unnecessary. Stainless steel fabrics and the like would fall in the little or no stretch category. It should be noted that the cables for the peeling means are located within the press arms where they are free from interference with the press operation.

The conversion from flood to non-flood scoop is quickly accomplished by the novel design of the carriage assembly of the present invention. The scissors arrangement formed by the levers 52 and supporting the squeegee and floor bar assemblies, respectively, shifts in the manner shown in FIGS. 8 and 9 on the print and flood strokes, respectively. On the flood stroke, as shown in FIG. 9, the pool of ink is pushed across the screen S on the return stroke while the screen is in the elevated condition shown in FIG. 1. If it becomes desirable to convert to a non-flood scoop because of printing requirements, the cables are disconnected from the chase 24 and the press arms raised as shown in FIG. 1. The flood bar clamp is then released and a non-flood scoop of the type indicated at 727 in FIG. 10 is attached. The pivot pin or bearing bolt 71 is moved from the opening to the opening 131, passing through the same opening in the lever 52. Effectively, this shortens the length of the flood bar lever 70 and locates the scoop 79 to cooperate with the squeegee as shown on the return stroke. A similar change-over on the carriage assembly 40 is effected, the press head lowered, the cables reconnected to the chase 24 and the press is now ready for non-flood printing.

In printing fabrics and the like, the flood bar or scoop 79 may be replaced with a second squeegee to permit printing in both directions. In such event, the cam 108 will be timed to lower the press head 20 before the movement of the carriage is commenced. As noted above, the quick release of the chase 24 from the cable ends permits the operator to have access to the screen and squeegee and flood bars.

From the foregoing, it can be appreciated that conversion of the press from flood to non-flood for off-contact printing can be rapidly accomplished with little effort and no special skill required. The simplicity of the mechanism assures proper non-flood and flood functioning at all times, as the scissors action of the levers 52 and 70 is automatically actuated at every change in direction of the press. With the chase 24 in the down position and press head elevated, the squeegee and flood bar areeasily removed, cleaned or replaced.

The operation of the press will now be described. When the press is in the condition shown in FIG. 1, stock to be printed may be placed on the bed 14. A start button on the operating console 12 is actuated, energizing the motor 100 and causing the shaft to rotate. Through the main press drive linkage, the

drive arms

82 and 83 are moved to the forward position to bring the

carriage assemblies

40 and 41 to the front of the press. The condition of each carriage assembly during the forward or non-print stroke is illustrated in FIG. 9 for the flood-type operation while FIG. illustrates the condition assumed if a non-flood scoop is used. In either event, the'ink pool is moved to the front of the screen.

As the shaft 106 continues its rotation, the direction of the

main drive arms

82 and 83 reverses, causing the shuttle mechanism in each of the

respective carriage assemblies

40 and 41 to reverse, elevating the flood bar and lowering the squeegee into engagement with the screen S, such condition being illustrated in FIG. 8 and schematicallY in FIG. 5A. Just before the

arms

82 and 83 reverse direction, the press lift cam 108 reaches its low side and the press head is lowered to the condition shown in FlG..2. As the direction of the

drive arms

82 and 83 is reversed, the shuttle mechanisms are shifted to the condition Shown in FIGS. 8 and 5A which is illustrative of the initiation of the print stroke. The

main drive arms

82 and 83 continue to be rotated by the shaft 85 in a rearward direction to pull the squeegee across the screen S. In off-contact printing, as the shaft 85 moves, the peeling mechanism functions in the sequence shown in FIGS. 5A, 5B and 5C.- In oncontact printing, no elevation of the screen is ex perienced.

When the

main drive arms

82 and 83 reach the condition shown in dotted lines for the arm 83 in FIG. 4, the

respective carriage assemblies

40 and 41 are at the rear of the

respective press arms

22 and 23. At this time, the press lift cam 108 approaches the high side or rise condition to elevate the

arms

22 and 23, elevating the press head 20 to the condition shown in FIG. 1. The press will either dwell or stop in this condition, depending On the mode of operation selected. The desired mode of operation can be selected at the console 12, enabling the press to be operated at single stroke or continuously with a period of dwell at the elevated condition to permit removal of the printed stock and insertion of the unprinted stock. Single-cycle manual operation is also possible.

From the foregoing, it can been seen that the drive for the squeegee is directly From the arms and shifting of the squeegee and flood bar is simultaneous with the reversal of stroke, regardless of stroke length, and thereby eliminating the need for stops or the like with the undesirable noise and adjustment problems. The present design of press permits the stroke length to be shortened or lengthened from the front to back with one simple adjustment of the end of the arm 120 in the angular slot 123. This is made possible since the reversal of direction automatically actuates the shuttle mechanisms to shift the squeegee and flood bar rather than fixed stops of the prior art. Moreover, the novel squeegee and flood bar arrangement permits the rapid conversion from flood to non-flood scoop with a minimum of effort and without requiring excessive cost in press construction.

It is to be appreciated that the press of the present invention through its novel features is of rugged design which is quite economical to manufacture. Moreover, the press is of universal design, permitting it to be scaled up or down to meet particular customer requirements. The adjustments provided give great flexibility in its use.

Upon a consideration of the foregoing, it will become obvious to those skilled in the art that various modifications may be made without departing from the invention embodied herein. Therefore, only such limitations should be imposed as are indicated by the spirit and scope of the appended claims.

We claim:

1. In a screen-type printing press wherein a stencil screen is held against a surface to be printed and a squeegee is moved across said screen from front to back to force ink therethrough onto said surface to be printed, the improvement comprising peeling means connected to said stencil screen for elevating said stencil screen from said surface to be printed after said squeegee has passed over said screen, and to elevate said screen at a faster rate when said squeegee is centrally of said stencil screen than when said squeegee is at either said front or back of saId stencil screen.

2. The improvement in screen-type printing presses as defined in claim 1 wherein said peeling means is attached to a drive means, said drive means being operatively connected to said squeegee for moving said squeegee from front to back.

3. The improvement in screen-type printing presses as defined in claim 1 wherein said peeling means is substantially opposed in its elevating movement solely by the downward force exerted by said squeegee on said screen.

4. The improvement in screen-type printing presses as defined in claim 2 wherein said drive means for moving said squeegee from front to back includes a carriage assembly, lever means mounting said squeegee and a flood bar on said carriage assembly, shuttle means in cluding a pair of cam tracks engaged by cam follower means on said lever means, said shuttle means thereby shifting said lever means, to shift said squeegee and said flood bar relative to each other, said shuttle means being connected to said drive means such that said shifting of said squeegee and said flood bar will automatically occur on change of direction of said drive means.

5. The improvement in screentype printing presses as defined in claim 4 wherein means is provided in said drive means to shorten the length of the print stroke as measured from the front of the press.

6. A printing press having a frame, a bed supported on said frame and having an upwardly facing surface to receive work to be printed, a pair of spaced-apart arms mounted for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said arms to facilitate replacement of said screen and to allow movement of said chase with respect to said arms during off-contact printing and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said arms, drive means on said frame connected to said carriage assemblies to move said carriage assemblies from a rear portion of said arms to a forward portion of said arms and return, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to said positioning of said screen over said bed on said chase, said squeegee being brought into contact with said screen when said screen is in engagement with said work by said means supporting said squeegee and flood bar, said means shifting said squeegee and flood bar relative to each other to automatically and properly position the same during movement on said arms.

7. The printing press of claim 6 wherein said printing press is provided with registration means mounted thereon for locating said forward portion of said arms relative to said bed.

8. The printing press of claim 7 wherein said chase is provided with guide means at a forward end thereof to maintain registration as said chase is lifted from said bed relative to said arms to accomplish off-contact printing.

9. The printing press of claim 6 wherein said means for shifting said squeegee and flood bar includes first and second levers, said first lever being mounted on I said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and indepen dent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar.

10. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart arms mounted for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said arms, drive means on said frame connected to said carriage assemblies to move said carriage assemblies from a rear portion of said arms to a forward portion of said arms and return, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting .an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to said positioning of said screen over said bed on said chase, said squeegee being brought into contact with said screen when said screen in is engagement with said work by said means supporting said squeegee and flood bar, said means shifting said squeegee and flood bar relative to each other to automatically and properly position the same during movement on said arms and including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, and a shuttle having oppositely-directed cam tracks therein, and cam follower means on each of said first and second levers cooperating with said oppositely-directed earn tracks in said shuttle, whereby movement of said shuttle causing shifting of said squeegee and flood bar.

H. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart arms mounted for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said arms and adapted for positioning over said work said bed, a carriage assembly mounted on each of said arms, drive means on said frame connected to said carriage assemblies to move said carriage assemblies from a rear portion of said arms to a forward portion of said arms and return, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and flood bar mounted on said carriage assemblies by means on each of said' carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to said positioning of said screen over said bed on said chase, said squeegee being brought into contact with said screen when said screen is in engagement with said work by said means supporting said squeegee and flood bar, said means shifting said squeegee and flood bar relative to each other to automatically and properly position the same during movement on said arms and including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, and having means on one of said levers to permit the pivot for the other of said levers to be moved relative to said one lever to convert said carriage to a non-flood scoop printing operation.

12. The printing press of claim 6 wherein said drive means mounted on said frame includes a drive arm disposed outside each of said arms supporting said carriage assemblies, to permit scaling in size of said press, each of said drive arms being joined to said means for shifting said squeegee and flood bar relative to each other.

13. A'printing press having a frame, a bed supported on said frame and having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said support arms, drive means mounted on said frame and connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion of each of said support arms to a forward portion thereof and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable abouta common axis for shifting said carriage assemblies on said support arms, said support arms being disposed on an axis which is in substantial vertical alignment with said axis of said L- shaped arms to facilitate adjustment of the length of the print stroke and to reduce the size of the press and the space required for its operation.

14. The printing press of claim 13 wherein said drive means includes a power drive shaft, adjustable linkage means to impart motion from said power drive shaft to said L-shaped arms, said power drive shaft being disposed on an axis below said axis of said support arms and above the axis of said drive means, thereby to permit adjustment of the length of stroke of said carriage.

15. A printing press as defined in claim 13 wherein each of said carriage assemblies includes a carriage housing supported on each of said arms, a squeegee and a flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, said means on said carriage housing being responsive to changes in direction of said L-shaped arms to shift said squeegee and flood bar relative to each other, thereby to automatically and properly position the same during movement on said arms.

16. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each-of said support arms, each of said carriage assemblies including a carriage housing supported on each of said arms,

a squeegee and a flood bar mounted on said carriage assemblies by means on each of said carriagehousings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, drive means mounted on said frame connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion each of said support arms to a forward portion of each of said support arms and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said means on said carriage housings being responsive to changes in direction of said L-shaped arms to shift said squeegee and flood bar relative to each other thereby to automatically and properly position the same during movement on said arms, each of said carriage assemblies including brake means to assure shifting of said squeegee and flood bar on reversal of direction of said carriage movement.

17. The printing press of claim 15 wherein said means for shifting said squeegee and flood bar includes first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar.

.a squeegee and a flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, said means including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement rela tive to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, said means shiftin g said squeegee and flood bar also including a shuttle having oppositely-directed cam tracks therein, and cam follower means on each of said first and second levers cooperating with said oppositely-directed cam tracks in said shuttle, whereby movement of said shuttle causes shifting of said squeegee and flood bar, and drive means mounted on said frame connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion of each of said support arms to a forward portion of each of said support arms and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said means on said carriage housings being responsive to changes in direction of said L-shaped arms to shift said squeegee and flood bar relative to each other thereby to automatically and properly position the same during movement of said arms.

19. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement tward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said support arms, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and a flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, said means including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, and including means on one of said levers to permit the pivot for the other of said levers to be moved relative to said one lever to convert said carriage to a non-flood scoop printing operation, and drive means mounted on said frame connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion of each of said support arms to a forward portion of each of said support arms and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said means on said

Claims

4. The improvement in screen-type printing presses as defined in claim 2 wherein said drive means for moving said squeegee from front to back includes a carriage assembly, lever means mounting said squeegee and a flood bar on said carriage assembly, shuttle means including a pair of cam tracks engaged by cam follower means on said lever means, said shuttle means thereby shifting said lever means, to shift said squeegee and said flood bar relative to each other, said shuttle means being connected to said drive means such that said shifting of said squeegee and said flood bar will automatically occur on change of direction of said drive means.

5. The improvement in screen-type printing presses as defined in claim 4 wherein means is provided in said drive means to shorten the length of the print stroke as measured from the front of the press.

9. The printing press of claim 6 wherein said means for shifting said squeegee and flood bar includes first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar.

10. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart arms mounted for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said arms, drive means on said frame connected to said carriage assemblies to move said carriage assemblies from a rear portion of said arms to a forward portion of said arms and return, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to said positioning of said screen over said bed on said chase, said squeegee being brought into contact with said screen when said screen in is engagement with said work by said means supporting said squeegee and flood bar, said means shifting said squeegee and flood bar relative to each other to automatically and properly position the same during movement on said arms and including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, and a shuttle having oppositely-directed cam tracks therein, and cam follower means on each of said first and second levers cooperating with said oppositely-directed cam tracks in said shuttle, whereby movement of said shuttle causing shifting of said squeegee and flood bar.

11. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart arms mounted for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said arms and adapted for positioning over said work said bed, a carriage assembly mounted on each of said arms, drive means on said frame connected to said carriage assemblies to move said carriage assemblies from a rear portion of said arms to a forward portion of said arms and return, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed rElation to said positioning of said screen over said bed on said chase, said squeegee being brought into contact with said screen when said screen is in engagement with said work by said means supporting said squeegee and flood bar, said means shifting said squeegee and flood bar relative to each other to automatically and properly position the same during movement on said arms and including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, and having means on one of said levers to permit the pivot for the other of said levers to be moved relative to said one lever to convert said carriage to a non-flood scoop printing operation.

13. A printing press having a frame, a bed supported on said frame and having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said support arms, drive means mounted on said frame and connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion of each of said support arms to a forward portion thereof and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said support arms being disposed on an axis which is in substantial vertical alignment with said axis of said L-shaped arms to facilitate adjustment of the length of the print stroke and to reduce the size of the press and the space required for its operation.

16. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said support arms, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegeE and a flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, drive means mounted on said frame connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion each of said support arms to a forward portion of each of said support arms and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said means on said carriage housings being responsive to changes in direction of said L-shaped arms to shift said squeegee and flood bar relative to each other thereby to automatically and properly position the same during movement on said arms, each of said carriage assemblies including brake means to assure shifting of said squeegee and flood bar on reversal of direction of said carriage movement.

18. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement toward and away from said bed, a screen removably mounted on a chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said support arms, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and a flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, said means including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, said means shifting said squeegee and flood bar also including a shuttle having oppositely-directed cam tracks therein, and cam follower means on each of said first and second levers cooperating with said oppositely-directed cam tracks in said shuttle, whereby movement of said shuttle causes shifting of said squeegee and flood bar, and drive means mounted on said frame connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion of each of said support arms to a forward portion of each of said support arms and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said means on said carriage housings being responsive to changes in direction of said L-shaped arms to shift said squeegee and flood bar relative to each other thereby to automatically and properly position the same during movement of said arms.

19. A printing press having a frame, a bed supported on said frame having an upwardly facing surface to receive work to be printed, a pair of spaced-apart support arms mounted on said frame for pivoting movement toward and away from said bed, a screen removably mounted on a Chase, said chase being mounted for pivoting movement beneath said support arms and adapted for positioning over said work on said bed, a carriage assembly mounted on each of said support arms, each of said carriage assemblies including a carriage housing supported on each of said arms, a squeegee and a flood bar mounted on said carriage assemblies by means on each of said carriage housings for supporting an end of said squeegee and flood bar for pivoting movement relative to each other in timed relation to movement of said screen over said bed, said means including first and second levers, said first lever being mounted on said housing for pivoting movement relative thereto, said second lever being mounted directly on said first lever for pivoting movement relative to and independent of said first lever and said housing, and clamp means on the end of said levers for supporting said squeegee and flood bar, and including means on one of said levers to permit the pivot for the other of said levers to be moved relative to said one lever to convert said carriage to a non-flood scoop printing operation, and drive means mounted on said frame connected to said carriage assemblies for reciprocating each of said carriage assemblies from a rear portion of each of said support arms to a forward portion of each of said support arms and return, said drive means being disposed within the side margins of said chase and including a pair of rigid L-shaped arms movable about a common axis for shifting said carriage assemblies on said support arms, said means on said carriage housings being responsive to changes in direction of said L-shaped arms to shift said squeegee and flood bar relative to each other thereby to automatically and properly position the same during movement on said arms.

20. The printing press of claim 18 wherein said L-shaped drive arms are disposed outside each of said arms supporting said carriage assemblies and each of said L-shaped drive arms has means for joining it to said shuttle for shifting said squeegee and flood bar relative to each other.