US3929069A - Gripper control for sheet-fed rotary printing presses - Google Patents

Abstract

A gripper control for a sheet-fed printing press includes a shaft on which an impression cylinder is mounted. A cam is mounted on the shaft and the cam operates an actuating means to provide an oscillating motion to a gripper means for feeding sheets to the press in synchronism with the rotation of the shaft. Spring means are provided to apply a biasing force to the oscillating motion of the gripper means, and control means are provided to control the spring force dependent on the rotation of the shaft.

Description

United States Patent 1 Jahn [ Dec. 30, 1975 GRIPPER CONTROL FOR SHEET-FED ROTARY PRINTING PRESSES [75] Inventor: Hans-Georg Jahn,Wieslock,

Germany [73] Assignee: Heidelberger Druckmaschinen AG,

Heidelberg, Germany [22] Filed: May 23, 1973 [21] Appl. No.: 363,043

[30] Foreign Application Priority Data May 23, 1972 Germany 2224732 [52] US. Cl. 101/232; 101/408; 271/277 [51] Int. C1. B65H 5/10 [58] Field of Search 271/268, 277; 101/408-412, 232, 246

[56] References Cited UNITED STATES PATENTS 834,107 3/1952 Kolland 101/409 2,767,653 10/1956 Babicz 101/409 2,776,136 1/1957 Dietrich.... 101/408 2,926,909 3/1960 Jantzen 271/268 2,991,072 7/1961 Dietrich 101/409 3,151,552 l0/1964 101/246 3,257,109 6/1966 271/268 3,385,597 5/1968 101/411 3,412,995 11/1968 271/268 3,463,484 8/1969 Rudolph 101/409 FOREIGN PATENTS OR APPLICATIONS 1/1963 Canada 271/268 Primary Examiner.1. Reed Fisher Attorney, Agent, or Firm-Herbert L. Lerner [57] ABSTRACT A gripper control for a sheet-fed printing press includes a shaft on which an impression cylinder is mounted. A cam is mounted on the shaft and the cam operates an actuating means to provide an oscillating motion to a gripper means for feeding sheets to the press in synchronism with the rotation of the shaft. Spring means are provided to apply a biasing force to the oscillating motion of the gripper means, and control means are provided to control the spring force dependent on the rotation of the shaft.

2 Claims, 6 Drawing Figures U.S. Patent Dec. 30, 1975 'Sheet1of2 3,929,069

US. Patent Dec. 30, 1975 Sheet 2 of2 3,929,069

F'ig. h

Fig.5

Fig.6

GRIPPER CONTROL FOR SHEET-FED ROTARY PRINTING PRESSES This invention relates to a gripper control for sheetfed, rotary printing presses. More particulary the invention relates to a gripper control of the type in which a cam is mounted on a shaft and drives a hollow shaft supporting the gripper mechanism in an oscillating manner by means of a cam roller and a drive linkage. A pretensioned torsion spring which biases the cam roller against the cam by means of the drive linkage is accommodated in the hollow shaft.

Cam-controlled gripper drives are known in which the grippers are swung or operated in a form-locking manner by means of auxiliary cams. However, these known drives are very expensive and are justifiable only for printing presses handling large sheet sizes.

Cam-controlled gripper drives are also known in which a cam roller is held in positive engagement with a cam by means of a spring. These known drives have the disadvantage that due to the large angle of oscillation of the grippers, large spring excursions or expansion are produced which result in spring forces that have an unfavorable effect on the drive mechanism. The maximum speed of the printing press as well as its proneness or tendency to produce striping are strongly influenced by the above-mentioned characteristic of the spring forces.

In other known gripper drives, attempts have been made to correct the above-mentioned disadvantages and shortcomings by providing particularly long, soft springs which requires less applied forces to effect contraction and expansion. However, due to space limitations, such long springs cannot be accommodated in all printing machines. Although gripper drives are also known which operate with short, strong springs, such known drives must co-control the spring engagement point by means of a second cam so that the spring forces do not rise excessively. The additionally required cam mechanism for controlling the spring forces requires a considerable expenditure.

Accordingly, it is an object of the present invention to overcome the disadvantages of the aforementioned prior art arrangements and to provide for keeping the spring forces within a range favorable for the functioning of the gripper drive by utilizing means which are not large and which require little space.

The aforementioned object is achieved by providing a torsion spring having one end which is fastened to a bearing shaft and which is rotatably disposed in a hollow shaft. The bearing shaft protrudes from the hollow shaft and is provided with an eccentric cam. A chain is connected to the curve segment of the eccentric cam closest to the axis of symmetry of the bearing shaft. The chain is connected to a crank mounted on a shaft in such a manner that the chain is wound onto or unwound from the eccentric cam during each back and forth rotation of the hollow shaft.

By providing the eccentric cam on the bearing shaft, a rise in the tension of the torsion spring during the back and forth movement of the grippers can be avoided almost completely. As a result it is possible to increase the transporting speed of the gripper substantially.

Other featurcswhichare considered as characteristic not intended to be limited to the details shown, since variousmodifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a schematic representation illustrating the operation of a gripper drive according to one embodiment of the invention.

FIG. 2 is a top view, partly in section, of the gripper drive represented in FIG. 1.

FIG. 3 is an elevational view of the spring compensation arrangement of the gripper drive.

FIG. 4 is a time-travel diagram or graph in which the degrees of arc are plotted on the abscissa and the angle of rotation of the drive lever and bearing shaft are plotted on the ordinate.

for the invention are set forth intlie appended claims?- Although the invention is illustrated and described in relationship to specific embodiments, it is nevertheless FIG. 5 is a diagram or graph representing the difference between the angles of rotation of the drive lever and the bearing shaft.

7 FIG. 6 is a diagram or graph representing the spring characteristics of the torsion spring.

Referring to the drawing, there is shown in FIG. 2 a single-revolution shaft 1 of an impression cylinder 2. A control cam 4 is provided on the drive side of the printing press in front of a drive gear 3 for driving a gripper mechanism. The shaft 1 of the impression cylinder 2 is supported in sleeve bearings 5 and 6 in the side walls 7 and 8 respectively, of the printing press. A cam roller 9, which is rotatably mounted on a roller lever 10, runs on or follows the control cam 4. The roller lever 10 is fulcrumed at a bearing post 11 which is supported on the side wall 7. The roller lever 10 is attached or operatively connected to a drive lever 13 by means of a link 12. The drive lever 13 is firmly connected to a plug 14 which closes off the longitudinal end of a hollow shaft 15 and is firmly connected with the shaft 15.

The hollow shaft 15 carries a gripper bar 16 by means of two fulcrumed levers 17 and 18 and is supported in the side walls 7 and 8 by sleeve bearings 19 and 20 respectively. Inside the hollow shaft 15 there extends a torsion spring 21, one end of which is attached to the previously mentioned plug 14 and the other end of which is firmly connected with a bearing shaft member 22. This bearing shaft 22 is arranged rotatably in needle bearings 23 at that end of the hollow shaft 15 which faces away from the plug 14. The free end of the bearing shaft 22, which protrudes from the hollow shaft 15, is equipped with an eccentric circular cam 24 as best may be seen in FIG. 3. The cam 24 is arranged eccentrically to the axis of symmetry 25 of the bearing shaft 22. In the part of the curve of the cam 24 which is closest to the axis of symmetry 25, there is fastened a chain 26. The chain 26 is fastened in such a manner that it is wound up and down on the curved and eccentric surface 27 of the circular cam 24 when the bearing shaft 22 rotates or rocks back and forth. The other end of the chain 26 is connected with a crank 28 which is secured or pinned to the end of the shaft 1 of the impression cylinder 2 which protrudes from the center of the bearing of-thesidewalls 8 as shown in FIG n I During one revolution of the impression cylinder 2,

the roller lever 10 and thereby also the drive lever 13 is swung, due to the design of the cam 4, from the solid to the dashed position (FIG. 1) and back again. In this process the gripper bar 16 executes a movement toward a non-illustrated feed table and then moves back again to the impression cylinder 2 with a gripped sheet. The torsion spring 21 is pretensioned and therefore causes the cam roller 9 to be always pressed or biased against the running or operating surface of the control cam 4 by means of the drive lever 13, the link 12, and the roller lever 10. The crank 28 which also rotates with the impression cylinder 2 causes rotation of the bearing shaft 22 via the chain 26 in such a manner that the pretension of the torsion spring 21 changes only little, or not at all, during the stroke of the gripper bars 16.

The change of the pretension of the torsion spring 21 during the operating cycle can be varied as desired by appropriate design of the curved surface 27 of the cam 24. The possibility exists furthermore to adjust the pretension of the torsion spring 21 by adjusting the cam 24 on the bearing shaft 22.

The manner of operation of the gripper drive with gripper compensation, according to the invention, will now be explained with reference to FIGS. 4 to 6.

FIG. 4 shows a time-travel diagram in which the time t in degrees of arc is plotted on the abscissa and the rotation angles or of the drive lever 13 and B of the bearing shaft 22, respectively, are plotted on the ordinate.

The angle of rotation travelled by the drive lever 13 per unit time is shown by the curve c, while the curvef represents the angle of rotation of the bearing shaft 22. At the time t,, for example, the drive lever 13 has travelled through the angle of rotation a, while at the same time, the bearing shaft 22 has been rotated through the angle [3,. At this instance, the difference of the angles of rotation is therefore a, B 7 that is, the pretension of the torsion spring 21 has increased slightly, as the drive lever 13 leads the bearing shaft 22. When the gripper bars 16 swing back, however, the bearing shaft 22 leads, so that again a slight increase of the pretension of the torsion spring 21 occurs. Only at the reversal points, that is, when the sheet is taken over or passed on by the grippers, does the pretension correspond approximately to the predetermined magnitude. This continuous increase and decrease of the angle 7, the difference between the angles of rotation of the drive lever 13 and the bearing shaft 22, is shown in FIG. 5.

In FIG. 6 the spring characteristic h of the torsion spring 21 is shown wherein the torque is represented as a function of the spring excursion or twist, that is, the angle of rotation or angle of torsion of the torsion spring 21. a is the twist of the torsion spring 21 for the pretension torque M If the bearing shaft 22 did not co-rotate during the operating cycle, further torsion of the torsion spring 21 by the angle of rotation 01 would result in addition to the pretension. Accordingly, the torque produced by the torsion spring 21 would increase to M However, because the bearing shaft 22 does co-rotate through the crank 28 and the chain 4 26, only a slight additional torsion by an angle 'y occurs, so that the torque actually produced by the torsion spring 21 increases maximally only to M Due to the gripper motion and the co-rotation of the bearing shaft 22 via the supplementary drive 26, 28, 24, there results at the points of greater acceleration or deceleration, a slight increase of the pretension of the torsion spring 21, as the diagrams according to FIGS. 4 to 6 shown, while at those points where the acceleration and deceleration corresponds approximately to the value 0, practically only the preset pretension is effective. As a consequence of the above in the acceleration and deceleration phases, the lifting of the cam roller 9 from the control cam 4 is prevented by the slight increase of the torsion forces. This fact, as well as the avoidance of a larger rise of the torsion forces, permits substantially higher transport speeds of the gripper drive than would be the case without the spring compensation according to the invention. Because of the approximately uniform stress of the torsion rod or rods, the margin of safety against breakage is considerably increased.

I claim:

1. Gripper control means for sheet-fed printing presses, comprising a shaft on which an impression cylinder is mounted, oscillatably mounted gripper means for feeding sheets to the printing press, a cam mounted on said shaft, actuating means operatively connected between said cam and said gripper means to oscillate said gripper means by said cam and said actuating means upon rotation of said shaft, spring means connected to said actuating means to apply a spring force to the oscillating motion of said gripper means, and control means connected to said spring for controlling said spring force, said control means being connected to said shaft, wherein said gripper means includes a hollow shaft, said acutating means including a lever arrangement operable by said cam for oscillating said hollow shaft, and said spring means comprises a torsion spring extending in said hollow shaft, a bearing shaft member oscillatably mounted in said hollow shaft, said torsion spring having one end thereof attached to said bearing shaft member, said control means including a mechanical connection between said bearing shaft member and said impression cylinder shaft, said mechanical connection comprising a crank mounted on said shaft, a chain attached to said crank, an eccentric cam mounted on said bearing shaft member, said chain being attached to said cam at the curved segment of the latter closest to the axis of symmetry of said bearing shaft member, said chain being arranged on said cam in such a manner that the chain is wound on and off of said eccentric cam for each oscillation of said bearing shaft.

2. A gripper control according to claim 1 including bearing means rotatably supporting said bearing shaft member in said hollow shaft, said bearing shaft protruding from the end of said hollow shaft, said eccentric cam being mounted on said protruding end of said bearing shaft member.

UNITED sTATEs PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENTNO.: 29,069 DATED 1 December 30, 1975 mvrzmorars) HANS-GEORG JAHN it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the printed specificatien with respect to Foreign Applicatien Priority Data at line 10,

"May 23, 1972 Germany........222 r732", should read 23, o I a q I o c Signed and Scaled this A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Patents and Trademarks

Claims (2)

1. Gripper control means for sheet-fed printing presses, comprising a shaft on which an impression cylinder is mounted, oscillatably mounted gripper means for feeding sheets to the printing press, a cam mounted on said shaft, actuating means operatively connected between said cam and said gripper means to oscillate said gripper means by said cam and said actuating means upon rotation of said shaft, spring means connected to said actuating means to apply a spring force to the oscillating motion of said gripper means, and control means connected to said spring for controlling said spring force, said control means being connected to said shaft, wherein said gripper means includes a hollow shaft, said acutating means including a lever arrangement operable by said cam for oscillating said hollow shaft, and said spring means comprises a torsion spring extending in said hollow shaft, a bearing shaft member oscillatably mounted in said hollow shaft, said torsion spring having one end thereof attached to said bearing shaft member, said control means including a mechanical connection between said bearing shaft member and said impression cylinder shaft, said mechanical connection comprising a crank mounted on said shaft, a chain attached to said crank, an eccentric cam mounted on said bearing shaft member, said chain being attached to said cam at the curved segment of the latter closest to the axis of symmetry of said bearing shaft member, said chain being arranged on said cam in such a manner that the chain is wound on and off of said eccentric cam for each oscillation of said bearing shaft.

2. A gripper control according to claim 1 including bearing means rotatably supporting said bearing shaft member in said hollow shaft, said bearing shaft protruding from the end of said hollow shaft, said eccentric cam being mounted on said protruding end of said bearing shaft member.

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