US3926118A

US3926118A - Rotary printing press impression cylinder having clamping and sheet gripping devices

Info

Publication number: US3926118A
Application number: US497723A
Authority: US
Inventors: Friedrich Preuss
Original assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Current assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Priority date: 1973-08-16
Filing date: 1974-08-15
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16
Also published as: FR2240817A1; DE2341326A1; GB1435245A; DE2341326B2; FR2240817B1

Abstract

A printing press of the lithographic type having a pair of blanket cylinders and a cooperating impression cylinder. At least one of the blanket cylinders has, adheringly mounted thereon, a perforation strip presenting a line of regularly spaced perforation projections extending to a constant shallow height from the surface of the blanket. The impression cylinder is provided with a resilient, perforation-inducing covering layer for cooperating with the projections so that when the cylinders rotate together a sheet held by the impression cylinder is penetrated with a line of perforations. In the preferred embodiment of the invention the two blanket cylinders cooperating with the impression cylinder each have perforation strips, extending respectively at right angles to one another, and which successively engage the sheet on the impression cylinder, so that intersecting lines of perforations are produced in the sheet. In accordance with one of the aspects of the invention the impression cylinder is formed with a longitudinal gap or groove having a well defined edge and a recess extending continuously thereunder. The resilient covering layer has a mounting bar at one end which is clamped in the recess, with the covering layer being drawn over the edge of the groove in a tight bend. Mounted at the edge of the groove, adjacent the bend, is a gripper pad bar having a cooperating cyclically operated set of grippers for gripping the leading edges of successive paper sheets. The set of grippers and the gripper pad bar are both mounted in such a way as to permit temporary retraction away from the edge of the groove thereby to provide a radial clearance path for easy removal of the mounting bar and its associated covering layer when the mounting bar is unclamped. This permits rapid substitution of a conventional non-resilient impression blanket upon detatchment of the perforation strips to reestablish the normal printing function of the blanket cylinders.

Description

United States Patent 1191 Preuss Dec. 16, 1975 ROTARY PRINTING PRESS IMPRESSION CYLINDER HAVING CLAMPING AND SHEET GRIPPING DEVICES [75] Inventor: Friedrich Preuss, Sprendlingen,

Germany [73] Assignee: Roland Oifsetmaschinenfabrik Faber & Schleicher, Germany [22] Filed: Aug. 15, 1974 [21] Appl. No.: 497,723

[30] Foreign Application Priority Data Aug. 16, 1973 Germany 2341326 [52] U.S. Cl. 101/246; 101/136; 101/409; 101/415.1 [51] Int. Cl. B41F 21/04; B41F 29/04; B41F 7/10 [58] Field of Search 101/409, 410, 411, 246, 101/226, 227, 224, 415.1; 83/343-659, 679, 495, 698

[56] References Cited UNITED STATES PATENTS 1,545,791 7/1925 Owen 10l/415.1 1,579,180 3/1926 Thayer 1 l0l/227 X 1,579,182 3/1926 Thayer 1 lOl/227 X 1,582,390 4/1926 Evans l0l/4l5.l 1,686,065 10/1928 Blaine l0l/4l5.l 2,089,225 8/1937 Polachek 101/226 2,118,238 5/1938 Smith 101/177 2,599,776 6/1952 Peyrebrune 101/409 3,302,490 2/1967 Bishop 83/665 x 3,384,014 5/1968 Berg 101/415.1 3,430,560 3/1969 Nettleman 83/659 x 3,431,847 3/1969 Smith 61 al 101/226 x 3,587,382 6/1971 Boyd 83/698 Primary Examiner-J. Reed Fisher Attorney, Agent, or FirmWolfe, Hubbard, Leydig, Voit & Osann, Ltd.

571 ABSTRACT A printing press of the lithographic type having a pair of blanket cylinders and a cooperating impression cylinder. At least one of the blanket cylinders has, adheringly mounted thereon, a perforation strip presenting a line of regularly spaced perforation projections extending to a constant shallow height from the surface of the blanket. The impression cylinder is provided with a resilient, perforation-inducing covering layer for cooperating with the projections so that when the cylinders rotate together a sheet held by the impression cylinder is penetrated with a line of perforations. In the preferred embodiment of the invention the two blanket cylinders cooperating with the impression cylinder each have perforation strips, extending respectively at right angles to one another, and which successively engage the sheet on the impression cylinder, so that intersecting lines of perforations are produced in the sheet. In accordance with one of the aspects of the invention the impression cylinder is formed with a longitudinal gap or groove having a well defined edge and a recess extending continuously thereunder. The resilient covering layer has a mounting bar at one end which is clamped in the recess, with the covering layer being drawn over the edge of the groove in a tight bend. Mounted at the edge of the groove, adjacent the bend, is a gripper pad bar having a cooperating cyclically operated set of grippers for gripping the leading edges of successive paper sheets. The set of grippers and the gripper pad bar are both mounted in such a way as to permit temporary retraction away from the edge of the groove thereby to provide a radial clearance path for easy removal of the mounting bar and its associated covering layer when the mounting bar is unclamped. This permits rapid substitution of a conventional non-resilient impression blanket upon detatchment of the perforation strips to reestablish the normal printing function of the blanket cylinders.

1 Claim, 11 Drawing Figures U.S. Patent Dc.16,1975 Sheet10f3 3,926,118

US. Patent Dec. 16, 1975 Sheet 2 of3 3,926,118

U.S. Patent Dec.16,1975 Sheet3of3 3,926,118

ROTARY PRINTING PRESS IMPRESSION QYLINDER HAVING CLAMPING AND SHEET GRIPPING DEVICES As shown in US. Pat. No. 3,224,367, it is known to make a line of perforations in a sheet by means of a perforation wheel positioned opposite the impression cylinder of a lithograph press. It is also known to mount a perforation strip, presenting regularly spaced perforating projections, upon an impression cylinder for working against the resilient blanket of a blanket cylinder. However, because of the fact that a perforation strip requires a backing of substantial width for anchoring purposes, it is impossible, in this way, to secure intersecting lines of perforations. Moreover, the impression cylinder, upon which the perforation strips are secured, is often not readily accessible or demountable, and it is difficult to position the perforation strips precisely thereon.

It is the primary object of the present invention to provide a perforation system for a multi-color printing press which involves use of perforation strips, preferably extending at right angles, on respective blanket cylinders and which cooperate with a special resilient, perforation inducing covering layer on the impression cylinder. It is a related object of the invention to provide a novel construction of impression cylinder which includes provision for clamping a covering layer, having a mounting bar, in place and which in addition includes a gripper pad bar and set of cooperating cyclically operated grippers for gripping the leading edges of successive sheets of paper, with novel provision for retracting both the grippers and gripper pad bar well away from the covering layer and mounting bar to provide clearance for prompt removal of the mounting bar and covering layer from the cylinder, thereby to permit rapid substitution of a covering layer having different characteristics for use when the perforation strips are removed from the blanket cylinder for restoration of the printing function.

It is an object of the present invention in one of its aspects to provide an impression cylinder construction which has a provision for taut clamping of a covering layer as well as provision for cyclical gripping of successive paper sheets, for transport, and in which the clamping and gripping means are nested in the same groove in the cylinder without interference between their respective functions, and with novel provision for rapid substitution of covering layer.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIG. 1 is a schematic view multi-color sheet fed rotary printing press, the last printing unit of which is equipped for making of perforations.

FIG. 2 shows the blanket cylinders and cooperating impression cylinder of the last printing unit.

FIG. 3 is a developed view showing the blanket on the upper blanket cylinder of FIG. 2.

FIG. 4 is a developed view showing the blanket on the lower blanket cylinder of FIG. 2.

FIG. 4a shows, in face view, a fragment of the perforation strip used in FIGS. 3 and 4.

FIG. 4b is an enlarged section looking along the line 4b-4b in FIG. 4a.

FIG. 4c is an enlarged cross section looking along the line 4c-4c in FIG. 4a.

FIG. 5 is a fragmentary transverse section taken through the impression cylinder and looking along the line 55 in FIG. 6.

FIG. 6 is a fragmentary face view corresponding to FIG. 5.

FIG. 7 is an end view of the cam follower mechanism looking along the line 7-7 in FIG. 6.

FIG. 8 is a fragmentary view looking along the line 8--8 in FIG. 7.

While the invention has been described in connection with a preferred embodiment, it will be understood that I do not intend to be limited to the particular embodiment shown but intend, on the contrary, to cover the various alternative and equivalent forms of the invention included within the spirit and scope of the appended claims.

Turning now to FIG. 1 of the drawings there is shown a typical printing press 10

havingthree printing units

11, 12, 13 of the five-cylinder type having interconnecting

conveyors

14, 15, 16 and terminating in a delivery mechanism 17, the conveyors and delivery mechanism being conventional and not part of the present invention. Taking the printing unit 13 as typical, it includes an impression cylinder 20 (FIG. 2) having cooperating

blanket cylinders

21, 22 which, in turn, have

respective plate cylinders

23, 24. The means for inking and dampening the plates on the plate cylinders are not shown and will be understood to be conventional. The resilient blankets on the

blanket cylinders

21, 22 are indicated at 31, 32, the blankets being held in place by conventional mounting and tensioning means 33, 34. The blankets are shown in developed form, that is, laid out flat, in FIGS. 3 and 4.

When using the press 10 for conventional printing a paper sheet, fed into the unit 11, is printed in two colors, then passes to unit 12 for printing in two additional colors. Following this the sheet is transferred to unit 13 where it is printed in two more colors, making a total of six.

In accordance with the present invention the third press unit 13 are quickly and easily adapted for perforating the sheet, instead of performing a printing function, using perforation strips secured to the

blankets

31, 32 of the blanket cylinders and with the normal, relatively hard, covering of the impression cylinder being replaced by a special resilient, perforation-inducing covering for cooperating with the perforating projections on the blankets and with the sheet being acted upon successively by the latter.

Thus in carrying out the invention the blanket 31 of the blanket cylinder 21, and which is shown in FIG. 3, has cemented to it a set of perforation strips 40 arranged in parallel relation. Similarly the blanket 32 on cylinder 22, shown in FIG. 4, has a set of perforation strips 41 arranged at right angles to the first set; for example, where the perforation strips are peripheral on blanket 31, they are axially arranged on blanket 32.

To understand the construction of an individual perforation strip 40, reference is made to FIGS. 4a-4c. The strip includes a metal member 43 of hard metal but of light flexible construction, in inverted T shape, having a mounting portion 44 and series of spaced, upwardly extending projections 45 o shallow height. The length and spacing of the individual projections 45 depends upon the desired length and spacing of the perforations. To hold the perforating element 43 in 3 place upon the rubber blanket 31, it is secured on the underside of a strip of tape 46, with the projections 45 projecting through along the center line of the tape, and with the tape being backed by an adhesive layer 47 of a type capable of sticking to the surface of the rubber blanket.

In accordance with one of the important aspects of the present invention the impression cylinder 20, instead of having the usual, relatively stiff covering, or impression blanket, utilized for back up purposes in lithograph printing, and which may be typically made of copper or hard rubber, the impression cylinder is provided with a resilient perforation-inducing covering 50 which may be formed of rubber or a resilient plastic having rubber-like characteristics and of such durometer rating as to accommodatingly receive the tips of the perforation projections 45 on the blanket cylinders thereby to cause the projections to cleanly break through the thickness of the supported sheet of paper S to form crisp and well defined lines of perforation or weakening. Further in accordance with the invention the perforation-inducing layer 50 is provided at one end with a longitudinally-extending mounting, or reinforcing, bar 51 for purposes of anchoring the covering 50 tautly in place.

Still further in accordance with the invention a groove is formed longitudinally in the surface of the cylinder for accommodating spaced clamping devices for clamping the reinforcing bar in place and for accommodating a gripper pad bar as well as a set of cooperating grippers for holding a sheet on the surface of the cylinder and with provision for simultaneous retraction, to a clearance position, of both the grippers and the gripper pad bar so that, upon release of the clamping devices, the reinforcing bar and its associated covering layer may be conveniently and quickly removed, and a conventional impression blanket substituted, so that, upon removal of the perforation strips, normal printing may be resumed. The three types of mechanism, and the supporting means therefor, are mounted in a longitudinally extending groove 60 formed in the impression cylinder having a well defined edge 61 and a floor 62. Extending longitudinally under the edge, and at floor level, is a continuous corner recess 63 which receives the mounting bar 51.

For the purpose of clamping the mounting bar in place a plurality of clamping devices 70 are provided at spaced positions within the groove, but only one of which is shown in FIG. 6. The illustrated device which may be referred to as a clamping dog is of L cross section having a first, or clamping, leg 71 and a second, or supporting, leg 72, with the end of the clamping leg 71 projecting over the edge of the mounting bar 51 as shown in FIG. 5. The clamping leg 71 is penetrated by a clamping screw 73, the lower end of which is threaded into the cylinder body. For raising the clamping member away from the reinforcing bar when the screw is loosened, is a leaf spring 74, of C shape, nested against the floor 62.

By providing a plurality of clamping devices 70 at spaced intervals along the groove 60, the intervening space may be utilized for installation of sheet gripping mechanism, to be discussed.

At its opposite end the covering layer 50 engages a tensioning bar 75 having a clamping strip 76 held by screws 77. Tension is applied in non-retrograde fashion by a worm wheel 78 rotated by a worm 79 (FIG. 6).

Thus in carrying out the present invention there is provided adjacent the wall-defined edge 61 of the groove, and the resilient layer 50 which is tightly bent over such edge, a gripper pad bar 80. The bar is supported upon a series of mounts 81, only one of which is shown in FIG. 6. Such mount is of L shape having a radially projecting portion 82, which carries the bar at its outer end, and projection 83 extending at right angles thereto. For pivoting the mount, a pivot pin 84 is provided near the junction of the portions 82, 8.3, the ends of the pin being received in alined apertures in the lateral portions of a mounting block 85 which is secured to the floor of the groove by means of screws 86.

The projection 83 of the mount is threadedly engaged by an actuating screw 86. Turning the screw in a clockwise direction causes the tip of the screw to react against the bottom of the groove, thus rotating the mount 81 clockwise to bring the gripper pad bar 80 into an operating position, illustrated in FIG. 5, closely adjacent the bend in the covering layer 50.

In order to prevent the gripper pad bar from being advanced too far, which would run the risk of crushing the layer 50, a limit stop in the form of a set screw 87 is provided in a bracket 88. Thus the separate actuating screws 86 in each of the mounts 81 may be turned until tightening occurs which indicates that the projections 83 have bottomed against the respective set screws 87.

For the purpose of cooperating with the gripper pad bar 80, a gripper assembly is provided having a gripper shaft 90 mounting individual grippers of which four are indicated at 91-94. The gripper shaft is journaled in bores 95 formed in end members 96, only one of which is shown (FIG. 6). For the purpose of cyclically rocking the gripper shaft 90, a rocking mechanism is provided at the end of the shaft in the form of a two-part cam follower device including a follower lever 101 and a cooperating adjusting arm 102. The follower lever carries, at its tip, a follower roller 103 which rides against a generally circular cam surface 104 on the associated stationary frame structure (FIG. 7). The cam surface is so formed as to rock the cam follower lever 101, and hence the gripper shaft, on a cyclical basis for opening and closing the grippers.

To understand the details of the rocking mechanism 100, reference is made to FIGS. 6-8.,I-Iere it will be noted that the followerlever 101 is releaseably clamped to the shaft 90 by means of a clamp 105 while the adjusting arm 102 is permanently pinned to the shaft by means of a pin 106. Threaded into the arm is an adjusting screw 107 having a tip which engages the end 108 of the lever 101. For biasing the grippers toward open position, a spring 109 is secured by a pin 110 to the adjusting arm 102, the other end of the spring being anchored to the cylinder by means not shown. The cam surface 104 is faced to work against the spring and to provide positive closure of the grippers against the leading edge of the sheet S.

In accordance with the present invention means are provided for retracting both the gripper pad bar 80 and the grippers 91-94 to a clearance position to provide radial access for the reinforcing bar 51 at the end of the cover 50. In the case of the grippers, this is accomplished by releasing the clamp 105 which secures the lever 101 to shaft 90. Following this, the gripper adjusting screw 107 is unscrewed with respect to the arm 102 so that the arm may rock with respect to the lever 101 under the influence of the spring 109, thereby to rotate the shaft 90 in a direction ,to well clear of the gripperpad bar 80.

Subsequently, the actuating screws 86 in the respective bar mounts'S'l are u'riscrewed causing the mounts to rock counterclockwise as viewdin FlGuS, thereby retracting the gripper pad bar80 .well away from the bend of the cover member 50 and providing a clear radial path for the entry and exit of mounting bar 51.

Consequently, upon unscrewing the screws 73, the springs 74 expand, loosening the clamping members 70 so that the mounting bar 51 is free to be withdrawn outwardly through the aforementioned radial clearance passage.

This permits prompt and easy substitution of a conventional impression cylinder blanket having a similar mounting bar. At the opposite or tensioning end the resilient covering layer is disengaged by loosening the clamping screws 77 on bar 75, and the end of the new swing the grippers 9 l 94 blanket is substituted. With a new mounting bar recessed in corner 63, the clamping screws 73 are retightened to hold it securely in place. The bar 75, at the other end, with the new blanket attached, is rotated to the extent necessary to put the blanket under tension.

Following this, the screws 86 on the bar mounting members 81 are turned tight, causing the gripper pad bar 80 to swing broadwise in a clockwise direction to the operating position shown in FIG. 5.

Finally, the adjusting screw 107 forming a part of the cam follower assembly is screwed inwardly with the reaction against lever 101 causing gripper shaft 90 to rotate against the force of the spring 109, thereby advancing all of the grippers 91-94 into normal operating position. Such position can be accurately reestablished by calibrating the screw 107 as indicated in FIG. 8 and by providing an arm 107a on the screw which cooperates with a fixed, but removable stop 107b. The clamp 105 is then tightened to hold the lever 101 in place on the shaft.

This completes restoration of the impression cylinder to the printing mode. Subsequently, when it is desired to perforate the printed product, the procedure is reversed: Perforation strips 40, 41 are secured to the rubber blankets 31, 32. The gripper shaft is backed off by loosening clamp 105 and by unscrewing the adjusting screw 107. The gripper pad bar 80 is similarly backed off by unscrewing the actuating screws 86. Finally, the clamping screws 73 are unscrewed to release the clamping members 70 to permit substitution of mounting bars; clamping screws 73 are then tightened, followed by tightening of actuating screws 86 and advancement of adjusting screw 107.

It will be apparent that the device satisfies the objects of the invention. By providing two sets of perforation strips at relative right angles to one another on two different blanket cylinders cooperating with the same impression cylinder, intersecting perforations of high quality can be readily achieved. By contrast it is not possible to provide intersecting perforations where perforating strips extend in rectangular directions on the same cylinder because of the problems of overlapping strips at 90, the problem being worsened by the fact that the strips are quite wide, because of the attachment area, so that one strip tends to mask the other at the region of intersection. Mounting the strips on the respective blanket cylinders is a relatively easy matter since the blanket cylinders are, in most press designs, readily accessible. By contrast, the impression cylinder is usually difficult of access. However, notwithstanding 6 this, the present invention provides for easy and quick substitution of a resilient perforation-inducing. blanket for the relatively non-yielding surface used inthe printing mode The turning of a few screws between loose andtight positions is virtually all that is required to substitute a covering layer for perforation purposes,

and this may be done quickly and easily even though the impression cylinder may not be readily accessible.

The invention disclosed andclaimed herein has general application to multi-color printing presses of the lithographic type both with respect to new presses and, by modification and substitution of impression cylinder, presses which are already in the field.

While the invention is primarily concerned with establishing a line, or lines, of perforations in a printed sheet, the invention is equally applicable to forming grooves in a sheet, and in particular intersecting grooves. This may be accomplished by making the perforation projections 45 (see especially FIG. 4b) continuous and of slightly less height than required for perforation; consequently the term perforation projections should be understood to include this possibility. Also while the invention contemplates interchanged substitution of the regular impression blanket by a resilient covering layer, the invention is not limited thereto and the regular relatively non-resilient impression blanket may if desired be permanently mounted on the impression cylinder. In such event the perforationinducing layer 50 may simply be superimposed, and held in place by its mounting bar 51 when the perforation function is employed, the blanket cylinders under such circumstances being approximately backed off the amount necessary to accommodate the added thickness.

The term rubber as used herein denotes any tough, resilient, rubber-like material.

It is one of the features of the present construction that the perforating strip, in accomplishing perforation, is mounted upon a first resilient layer, namely, the rubber blanket on the blanket cylinder with the perforating projections thereof working against a second resilient layer, namely, the covering layer on the impression cylinder. This is found to provide an improved result compared to the usual situation where the perforating strip is mounted upon a relatively hard and unyielding surface as, for example, the surface of the conventional impression cylinder blanket.

What I claim is:

1. In an impression cylinder for a lithograph printing press, the combination comprising a body having a gap in the form of a longitudinally extending groove having a well-defined longitudinal edge and a recess extending continuously thereunder, a covering layer having a rigid mounting bar at one end, clamping means for clamping the mounting bar in the recess, means recessed in the cylinder for tensioning the opposite end of the covering layer so that the layer is drawn into a tight bend over the edge of the groove and thence over the surface of the cylinder, a gripper pad bar extending continuously along the edge of the groove, spaced mounts seated in the groove for mounting the gripper pad bar and for releasably holding it in a normal position in which it is snugly adjacent the bend in the covering layer, each mount being of L shape having a radial portion supportively engaging the gripper pad bar and having a projecting arm portion at right angles thereto with a pivot at the bend of the L, a gripper shaft in the groove having a set of grippers cooperating the gripper pad bar from its normal position to a position separated from the bend of the covering layer to provide a clear radial path so that upon loosening of the clamping means the mounting bar and covering layer may be removed from the recess clear of the cylinder for replacement by an alternate mounting bar and covering layer.

Claims

1. In an impression cylinder for a lithograph printing press, the combination comprising a body having a gap in the form of a longitudinally extending groove having a well-defined longitudinal edge and a recess extending continuously thereunder, a covering layer having a rigid mounting bar at one end, clamping means for clamping the mounting bar in the recess, means recessed in the cylinder for tensioning the opposite end of the covering layer so that the layer is drawn into a tight bend over the edge of the groove and thence over the surface of the cylinder, a gripper pad bar extending continuously along the edge of the groove, spaced mounts seated in the groove for mounting the gripper pad bar and for releasably holding it in a normal position in which it is snugly adjacent the bend in the covering layer, each mount being of ''''L'''' shape having a radial portion supportively engaging the gripper pad bar and having a projecting arm portion at right angles thereto with a pivot at the bend of the ''''L'''', a gripper shaft in the groove having a set of grippers cooperating with the gripper pad bar, means including a cam follower on the shaft for engaging a relatively fixEd cam surface adjacent the cylinder for cyclical operation of the grippers for engaging the leading edges of successive sheets, means for disengaging the gripper shaft from the cam follower so that the grippers may be retracted well away from the gripper pad bar, the projecting arm portion having a limit stop to define the normal position and having screw means for retracting the gripper pad bar from its normal position to a position separated from the bend of the covering layer to provide a clear radial path so that upon loosening of the clamping means the mounting bar and covering layer may be removed from the recess clear of the cylinder for replacement by an alternate mounting bar and covering layer.