US3618516A

US3618516A - Support for offset cylinders of printing machines

Info

Publication number: US3618516A
Application number: US847083A
Authority: US
Inventors: Josef Jurny
Original assignee: Adamovske Strojirny AS
Current assignee: Adamovske Strojirny AS
Priority date: 1969-08-04
Filing date: 1969-08-04
Publication date: 1971-11-09
Anticipated expiration: 1988-11-09

Abstract

Offset cylinders of printing cylinders are mounted rotatably on a shaft, provided at both ends with formed discs with equally shaped circumferences. The shaft is supported in the sidewalls of the machine by sets of adjustable rollers bearing against said formed discs. At one end of said shaft is fixed a sleeve and mounted pivotably a lever provided with means for adjustment of their relative position. Control cam means are provided, acting on said lever pivotably mounted on the shaft, adjusting the position of said formed discs with respect to their supporting rollers and thus also the position of the offset cylinder with respect to the form cylinder and pressure cylinder.

Description

United States Patent [72] Inventor Josef Jurny Sebranice, Czechoslovakia [21] Appl. No. 847,083 [22] Filed Aug. 4, 1969 [45] Patented Nov. 9, 1971 [73] Assignee Adamovske Strojirny, narodni podnik Adamov, Czechoslovakia [54] SUPPORT FOR OFFSET CYLINDERS 0F PRlNTlNG MACHINES 8 Claims, 5 Drawing Figs.

[52] U.S.Cl 101/218 [51] Int. Cl 134117/04, 1341f 13/36 [50] Field nISearch 101/137, 139, 140, 143, 144, 182, 184,218,248, 247, 217

[56] Relerences Cited UNITED STATES PATENTS 2,615,393 10/1952 Albrecht 101/184 Primary Examiner-.1. Reed Fisher Arlorney-Richard Low ABSTRACT: Offset cylinders of printing cylinders are mounted rotatably on a shaft, provided at both ends with formed discs with equally shaped circumferences. The shaft is supported in the sidewalls of the machine by sets of adjustable rollers bearing against said formed discs. At one end of said shaft is fixed a sleeve and mounted pivotably a lever provided with means for adjustment of their relative position, Control cam means are provided, acting on said lever pivotably mounted on the shaft, adjusting the position of said formed discs with respect to their supporting rollers and thus also the position of the offset cylinder with respect to the form cylinder and pressure cylinder.

PATENTEDNDV sum 3,618,51

saw 1 or a INVENTOR 7553f far/1 PATENTEI] NOV 9 IBYI SHEET 8 0F 4 INVENTOR J55 a ar/1y BY SUPPORT FOR OFFSET CYLINDERS OF PRINTING MACHINES BACKGROUND OF THE INVENTION This invention relates to the mounting of the shaft of an offset cylinder of printing machines and to a method for its pressure engagement with other cylinders.

The offset cylinder of a printing machine, in addition to its main function which is the transmission of a picture by means of the offset rubber coating, has to be arranged so as to enable a subsequent mutual pressure engagement with the form cylinder and with the pressure cylinder in predetermined cycles.

Known offset printing machines have the shaft of the offset cylinder mounted by means of its hearings in twin eccentric sleeves which by their relative turning cause the shaft and thus also the offset cylinder to approach to the pressure cylinder.

In lighter printing machines the offset cylinder is generally mounted rotatably on a shaft, both extremities of which are eccentric and are provided with bearings, supported between three eccentric bolts, by means of which the pressure with respect to the form and pressure cylinder is adjusted together with the adjustment of the printing machine. The turning of the eccentric shaft causes the movement of the offset cylinder to engage first with the form cylinder and then by further turning also with the pressure cylinder. Other arrangements comprise differently shaped discs maintained on each end of the shaft between three rollers and supporting rotatably the shaft of the offset cylinder. By turning the shaped discs, the offset cylinder is moved into engagement with the form cylinder and later also with the pressure cylinder. The adjustment of the pressure according to the thickness of the paper is accomplished by turning the eccentric bolts ofa couple ofsupporting rollers.

A drawback of the first mentioned arrangement is the sliding support of the shaft and of the eccentric sleeves which requires some device for lubricating the sliding surfaces. A further drawback is the mounting of the shaft of the offset cylinder by means of three elements so that even in case of a maximum accuracy the rigidity of the offset cylinder is influenced by the necessity of providing three mounting clearances.

A drawback of the second arrangement is that the offset cylinder is mounted rotatably on a shaft, which is in turn mounted by its eccentric extremities in bearings, usually roller bearings, which are by means of their external rings mounted between two eccentric bolts, the eccentricity of which is required for the adjustment of pressure with respect to printing cylinders. This double mounting of the off cylinder requiring clearance in the bearings also unduly influences its rigidity. Another drawback shows up in the course of disengagement of the offset cylinder from the form cylinder where by turning the eccentric shaft the axial distance of the offset and printing cylinder and thus also the distance of their toothed driving wheels is large. During operation of the machine when no printing is performed, the transmission gears are rather noisy. The increased axial distance influences also unfavorably the shape of the evolute of the toothed driving wheels of the printing cylinders.

The arrangement with differently shaped discs has the drawback, that their control has to be solved independently in both sidewalls of the machine and also the adjustment of the pressure in dependence on the thickness of the printed paper has to be performed by means of an auxiliary tool individually on both sides of the printing machine. The mechanism for turning the shaped discs has to be very rigid and due to the shape of the circumferential curves of said discs a considerable force is required for their turning. Due to the rigidity of the offset cylinder a substantial pressure on the pressure cylinder has to be maintained.

SUMMARY OF THE INVENTION It is an object of this invention to provide a support of the offset cylinder, which would enable an easy adjustment of the position of the offset cylinder.

It is a further object of this invention to enable an easy adjustment of the offset cylinder for printing of paper of different thickness.

It is still another object to significantly limit the influence of wear on all clearances.

Bearing these and other objects in mind the supporting structure of the offset cylinder comprises a shaft on which the offset cylinder is rotatably mounted by roller bearings, with formed discs with equally shaped circumference fixed on both ends of said shaft. The shaft is supported in the sidewalls of the printing machine by sets of three adjustable rollers, bearing against said formed discs. On one end of the shaft is fixed a sleeve and a pivotal lever with means for adjustment of their relative position. A control cam acting by way of said lever on said sleeve adjusts the position of the formed disc with respect to its supporting rollers and thus also the position of the offset cylinder with respect to the form cylinder and the pressure cylinder respectively. The circumference of the formed discs is shaped so as to approach first the offset cylinder to the form cylinder and subsequently to the pressure cylinder.

The arrangement of the support of the offset cylinder ac cording to this invention has the advantage, that the maximum rigidity of mounting is achieved, whereby any clearance of mounting of the shaft of the offset cylinder is eliminated by the use of a spring-loaded pressure roller. The formed discs fixed on the ends of the shaft of the offset cylinder enable the ap' proach and removal of the offset cylinder with respect to the form cylinder and pressure cylinder to the required distance so that the axial distance of the driving gears is negligibly changed. The circumference of the formed discs causes the offset cylinder to approach in pressure engagement with the form cylinder and with the pressure cylinder according to a predetermined time table. Another advantage of this arrange ment is that the pressure between the offset and pressure cylinder can be easily adjusted according to the thickness of the printed paper without affecting the pressure with respect to the fonn cylinder by manual operation of a single adjusting screw with reference to a scale. Another advantage arises from the circumstance that both formed discs are fixed directly on the shaft of the offset cylinder. The individual control systems for the formed disc on both ends of the shaft are not required and the whole control is accomplished by merely turning the shaft by means of a lever. The offset cylinder can be easily disassembled by retracting the levers supporting the supporting rollers. As the formed disc has a shape which is complementary with respect to the supporting rollers, the turning of the shaft with the formed discs is easy and the spring of the spring-loaded supporting roller eliminates inaccuracies in manufacture, contrary to known arrangements where this spring is completely engaged in relieving pressure of the formed discs.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the object of this invention is shown in the accompanying drawings where FIG. 1 is an elevation of the mounting of the offset cylinder with parts shown in section FIG. 2 is a side view in a section taken along the plan A-A as indicated in FIG. 1, with positions I and II of the offset cylinder FIG. 3 is a similar view with position III and IIIA of the offset cylinder FIG. 4 is the same view with the turned-down pivoting lever and FIG. 5 shows in enlarged scale the circumference of the formed disc as in FIG. 2 in the individual positions.

DESCRIPTION OF PREFERRED EMBODIMENT The arrangement according to this invention consists of an offset cylinder I mounted by means of bearings 2 rotatably on a shaft 3. Formed discs are fixed by means of set screws 4 at both ends of the shaft 3, each of said formed discs 5 mounted between

rings

6 and 34 respectively. which are themselves supported on

eccentric bolts

7 and 33, fixed in the sidewalls 8 of the machine and between a roller 9 rotatably supported on the bolt 10, fixed on a pivotable lever ll. The pivotable levers are located on both sides of the offset cylinder pivotably and are supported on bolts 12, fixed in the sidewalls 8. Adjusting screws 35 are provided on each of the pivotable levers l1, and have springs 13, resting with their other ends against sleeves I4, fixed to the sidewalls 8, bearing against said adjusting screws 35. Additional adjusting screws located in the sidewalls 8 bear against the faces of the shaft 3 of the offset cylinder 1. A sleeve 16 is fixed on one end of the shaft 3 and a lever 17 is pivotably mounted at this end. The sleeve 16 is provided with an adjusting screw I8 bearing against the lever 17. A scale 19 is provided on the face ofthe lever 17. A pointer 20 and a bolt 21 is fixed on the sleeve 16. A spring 22 is suspended with one end on the bolt 21 and with its other end on a bolt 23 fixed in the sidewall 8 of the printing machine.

The lever 17 is supported by a roller 24'rotatably supported on a bolt 25 fixed to a two-arm lever 26, itself pivotably supported on a bolt 27 fixed to the sidewall 8. A roller 29 is rotatably supported on a bolt 28 on the other end of the twoarm lever 26, said roller 29 being in engagement with the circumference ofa cam 32 of a not shown mechanism, causing a deviation of the cam 32 and thus also the bringing of the offset cylinder 1 in pressure engagement with the form cylinder 30 and with the pressure cylinder 30 and with the pressure cylinder 31 respectively.

The shape of the formed discs 5 is more exactly shown in FIG. 5. The roller 34 is substantially situated at the connecting line of the centers of the offset cylinder 1 and of the pressure cylinder 31, the roller 6 at the connecting line of the ofi'set cylinder 1 and the form cylinder 30, and the roller 9 is situated substantially opposite to both said

rollers

6 and 34. The disc 5 is divided into a series of corresponding sectors I, II, III; I, II', III, and; I", II", III" associated respectively with each of the

rollers

6, 34 and 9. The shaft 3 with the discs 5 is during operation of the printing machine turned for an angle indicated for instance between positions] and III. The shape of the circumference of the discs 5 between position I and II is circular, passing between positions II and III into a spiral-shaped depression. The shape of the parts between position I' and II is a convex depression passing between positions 11' and III into a circular shape. The shape of the discs 5 between position I" and II" is determined by the shape of the circular part between position land II and by the shape of the part between positions I and II' in order to meet the condition, that all three

rollers

6, 34 and 9 remain stable in the course of turning the shaft 3. The shape of the part between positions II" and III" is equally complementary to the shape of parts between positions II and III and the circular part between positions II and III'.

The described structure operates as follows:

In the position I as indicated in FIG. 2 the offset cylinder 1 is removed from the form cylinder 30 and from the pressure cylinder 31 whereby no printing is performed. At the beginning of printing, it is necessary to bring the offset cylinder 1 first in engagement for one revolution with the form cylinder 30 in order to transmit ink to the printing plate. By turning the cam 32, along which the roller 29 of the two arm lever 26 is rolling, the movement of lever 26 is transmitted by way of the roller 24 to the lever I7. By this means the lever 17 is turned, the turning of which caused the formed discs 5 and thus also the shaft 3 of the offset cylinder 1 to be displaced from position 1 to position 11 with respect to the roller 34 and correspondingly with respect to the

other rollers

6 and 9. The

formed discs 5 allows the offset cylinder 1 to move towards the form cylinder 30 until engagement occurs as seen in FIG. 2 by the dotted outline of cylinder shown by numeral II. As the circumference of the formed discs 5 corresponding to places between position I and II is exactly circular, the axial distance between the ofiset cylinder 1 and the pressure cylinder 31 remains the same. The circumferential shape of the formed discs 5 has however, between positions I and II the shape of a convex curve, which causes the offset cylinder 1 to approach towards the form cylinder 30. Further turning of the cam 32 by means of the not shown mechanism causes the formed discs 5 to be turned from position 11 to position Ill and as the circumferential curve has between positions II and III is a spiral shape. the offset cylinder 1 is moved towards the pressure cylinder 31 until engagement occurs, as seen in the dotted outline of cylinder 1 shown by numerals III. The pressure between the offset cylinder I and the form cylinder 30 does not change in course of this operations as the circumference of the formed discs 5 at places corresponding to positions between II and III is exactly circular. Reversing the direction at which the lever 17 is turned will trip off the offset cylinder and reverse the operation. Thus the sequential engagement of the form cylinder 30 and the pressure cylinder 31 by the offset cylinder 1 is obtained by oscillation of the discs 5 between the limits set by movement of lever 17. The shape of cam 32 or its proper movement can control lever 17 to effect cyclical movement. The adjustment according to the thickness of the paper is accomplished by means of the adjusting screw I8. By turning the adjusting screw 18 pressure is generated on the lever 17 which turns the shaft 3 and the formed discs 5 from position III into position IIIA as indicated in FIG. 3. The turning of the formed discs 5 between positions III and IIIA causes due to the spiral shape of the circumferential curve a pressing or removal of the offset cylinder 1 with respect to the pressure cylinder 31 according to the thickness of the printed paper sheets. The formed discs 5 fixed on both ends of the shaft 3 are pressed by rollers 9 mounted on the pivotable levers l1 and is biased by springs 13 between the two

rings

6 and 34 supported on the

eccentric bolts

7 and 33. The formed discs 5 have their circumference extended at places of engagement of the rollers 9 to such an extent that a minimum of force is required for turning of the formed discs 5. All clearances of the

rings

6, 34 and of the rollers 9 are removed by the force of the springs 13, so that the rigidity of the offset cylinder 1 is solely determined by the clearance of the bearings 2.

Iclaim:

I. In an offset printing machine having a rotatable offset cylinder mounted on a shaft and being shiftable into engagement with a form cylinder and a pressure cylinder respectively, a support for said offset cylinder comprising a frame having a pair of spaced walls, a shaped disc fixed to said shaft at each end of said cylinder, a plurality of rollers mounted in each of said sidewalls of said frame to bear against the circumference of said disc and to support the same, a sleeve fixed to at least one end of said shaft, a lever freely mounted about said shaft in proximity of said sleeve and extending radially outward therefrom, means for fastening said lever to said sleeve and means for angularly displacing said lever to rotate said shaft and change the relative position of said discs with respect to the supporting rollers, said discs being formed with cooperating surfaces adapted to engage with said rollers to cause said offset cylinder to selectively move into and out of engagement with said form and pressure cylinders respectively, on displacement of said lever.

2. The support according to claim 1 including means for mounting said support rollers on said wall for adjustable radial movement with respect to the shaft of said offset cylinders.

3. The support according to claim 2 wherein said rollers are spaced about the periphery of said shaft, at least one of said rollers being provided with biasing means for resiliently urging said rollers against said shaped discs and thereby against said other rollers.

4. The support according to claim 3 wherein said biased roller is mounted on a pivotal crank supported by the wall of said frame and provided with spring means for normally biasing said crank to cause said roller to engage said disc.

5. The support according to claim 1 wherein said means for fastening said lever to said sleeve is adjustable.

6. The support means according to claim 1 wherein said rollers comprise three in number, the first roller determining together with the shaped disc the position of the offset cylinder with respect to the form cylinder, the second roller determining together with said shaped disc the position of the offset cylinder with respect to the pressure cylinder, the third roller urging against said disc so as to maintain contact of said rollers with said disc, said discs being formed with predetermined sectors having circumferential contours corresponding to each of said rollers, said sectors being arranged so that engagement of said disc causes cooperation between said discs and rollers to effect sequential operation with said offset cylinder, said disc causing said first roller to move said offset cylinder to engage said form cylinder and subsequently to cause said first and second rollers to simultaneously move said offset cylinder to simultaneously engage said form and pressure cylinders.

7. The support according to claim 6 wherein the disc sectors corresponding to the first roller have a circumference comprising a circular portion and a depressed portion and wherein the sectors of the disc corresponding to said second roller comprises a depressed portion and a circular portion, the circular portion corresponding with said first roller and the depressed portion corresponding to said second roller causing engagement of said offset cylinder with said form cylinder only and the depressed portion corresponding with said first roller and the circular portion corresponding with said second roller causing engagement of the offset cylinder with both said form and pressure cylinders simultaneously, and the sectors corresponding to said third roller having a circumference comprising an extending curved portion adapted to maintain the disc and engagement under uniform pressure against said first and second rollers during rotation of said disc.

8. The support means according to claim 7, wherein said third roller is pivotally mounted and provided with resilient biasing means for urging said roller against said disc.

Claims

1. In an offset printing machine having a rotatable offset cylinder mounted on a shaft and being shiftable into engagement with a form cylinder and a pressure cylinder respectively, a support for said offset cylinder comprising a frame having a pair of spaced walls, a shaped disc fixed to said shaft at each end of said cylinder, a plurality of rollers mounted in each of said sidewalls of said frame to bear against the circumference of said disc and to support the same, a sleeve fixed to at least one end of said shaft, a lever freely mounted about said shaft in proximity of said sleeve and extending radially outward therefrom, means for fastening said lever to said sleeve and means for angularly displacing said lever to rotate said shaft and change the relative position of said discs with respect to the supporting rollers, said discs being formed with cooperating surfaces adapted to engage with said rollers to cause said offset cylinder to selectively move into and out of engagement with said form and pressure cylinders respectively, on displacement of said lever.