US3584577A

US3584577A - Rotary printing cylinders having engaged friction rollers to dampen vibration

Info

Publication number: US3584577A
Application number: US830758A
Authority: US
Inventors: Willi Jeschke
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1968-06-08
Filing date: 1969-06-05
Publication date: 1971-06-15
Anticipated expiration: 1988-06-15
Also published as: NL6908618A

Abstract

Rotary printing press includes a pair of parallel shafts surmounted respectively by a plate cylinder and a blanket cylinder, at least one travel ring acting as a Schmitz ring carried by each of the shafts and having a diameter equal at most to the diameter of the cylinder mounted on the respective shaft, at least one transmission located between the shafts and comprising two mutually peripherally engaging friction wheels, the friction wheels also peripherally engaging the travel ring respectively on the shaft adjacent thereto, the friction rollers being adjustably mounted so that frictional contact between the respective rollers and the travel rings and between the rollers themselves is maintained when the spacing between the shafts is varied.

Description

United States Patent ROTARY PRINTING CYLINDERS HAVING ENGAGED FRICTION ROLLERS TO DAMPEN VIBRATION 7 Claims, 3 Drawing Figs.

Int. Cl 841i 13/20 Field of Search 101/216- [56] References Cited UNITED STATES PATENTS 8/1948 Stempel 6/1967 Sarka ABSTRACT: Rotary printing press includes a pair of parallel shafts surmounted respectively by a plate cylinder and a blanket cylinder, at least one travel ring acting as a Schmitz ring carried by each of the shafts and having a diameter equal at most to the diameter of the cylinder mounted on the respec tive shaft. at least one transmission located between the shafts and comprising two mutually peripherally engaging friction wheels. the friction wheels also peripherally engaging the travel ring respectively on the shaft adjacent thereto, the friction rollers being adjustably mounted so that frictional contact between the respective rollers and the travel rings and between the rollers themselves is maintained when the spacing between the shafts is varied.

ROTARY PRINTING CYLINDERS HAVING ENGAGED FRICTION ROLLERS TO DAMPEN VIBRATION My invention relates to rotary printing press and more particularly to rotary printing press for offset printing having cylinders with axes adjustably spaced from one another.

Rotary printing presses for offset printing are known wherein the spacing between the axes of adjacent cylinders are adjustable, for example because of differences in thickness of the respective paper to be imprinted. In order to maintain a rotation of the cylinders that is angularly true and vibrationfree, especially flawless toothing is provided on the cylinder wheels, and the bearings of the cylinder journals are adjusted free of play by special means, such as tightly adjustable roller bearings, for example. In spite of such adjusting means, a vibration-free transmission of the rotary motion from one cylinder to another cylinder is not possible in every case. The slightest jolts as well as irregularities in the rotation of one of the cylinders or adjacent parts are transmitted to the other cylinder and cause load change or load variations on the flanks of the teeth provided on the cylinder wheels. This is sufficient to permit the production of disturbances in the form, for example, of streaks on printing (parallel to the cylinder axis). Such jolts and irregularities are produced, for example, by the running of the channels of the cylinder past the adjacent cylinder, by the running of the dampening or ink rollers up on and off the respective cylinders, and by the opening as well as closing of the paper grippers. 1n the heretofore known rotary printing presses, in fact, springy corunning devices or segments are provided at the transmission wheels for preventing play thereof so that the aforementioned jolts and irregularities cannot have any effect on the travel or operation of the cylinder and thereby also on the printing by the press. Means, in the form of resilient abutments, have also become known for eliminating, for example, the heretofore unavoidable jolts produced by the cams for the opening and closing movements of the grippers. However, such measures are very expensive and do not always lead to salutary results.

In other heretofore known rotary printing presses for offset printing, so-called Schmitz rings are provided on the plate cylinder and the blanket or rubber-covered offset cylinder. The Schmitz rings produce the following three effects.

I. The Schmitz rings have a constant friction fit and thereby have a damping effect on all types of vibrations.

2. The Schmitz rings can be given such dimension that a constant contact with the drive flanks of the cylinder wheels is afforded. The particular dimensioning calls for the Schmitz ring of the driving cylinder to have a slightly smaller diameter, for example 0.02 or 0.03 mm., than the Schmitz ring of the driven cylinder.

3. Due to the mutual prestressing of the Schmitz rings, any play of the cylinder bearing is stopped or forced into one direction.

Thus, with the aid of the Schmitz rings all jolts and irregularities in the rotary motion of the cylinders can be eliminated. The use of Schmitz rings for offset printing plants produces the disadvantage, however, that a constant spacing between plate cylinder and blanket cylinder must always be maintained due to the fact that the Schmitz rings will roll off under a given pressure. If it is then necessary to change the diameter of the plate cylinder, for example to attain an exactly predetermined running length of printing, the diameter of the blanket cylinder must be correspondingly changed while maintaining the Schmitz'ring pressure. This additional work expenditure has been felt to be burdensome by many printers. The same additional work of the just-described type must also be undertaken by the printer to maintain the Schmitz ring pressure when, for example, instead of paper of normal thickness, relatively thick cardboard is to be imprinted in the next printing operation and a specific running length of printing is prescribed therefor.

It is accordingly an object of my invention to provide rotary printing press which avoids the aforementioned disadvantages of the heretofore known rotary printing presses.

It is a further object of my invention to provide rotary printing press with simplified equipment for avoiding jolts as well as irregularities in the rotation of the cylinders of the printing press.

It is also an object'of my invention to provide rotary printing press in which the cylinders will have as much freedom from vibration without having to maintain the pressure of the Schmitz rings as is provided by maintaining constant pressure of the Schmitz rings.

With the foregoing and other objects in view, I provide in accordance with my invention, rotary printing press comprising a pair of parallel shafts, means for varying the spacing between the shafts, a plate cylinder and a blanket cylinder respectively mounted on the shafts, at least one travel ring or race acting as a Schmitz ring peripherally carried by each of the shafts and having a diameter at most equal to the diameter of the cylinder mounted on the respective shaft, at least one friction wheel transmission located between the shafts of the cylinders, the transmission comprising two friction wheels mutually engaging at the peripheries thereof one of the friction wheels peripherally engaging the travel ring on one of the shafts, and the other of the wheels peripherally engaging the travel ring on the other of the shafts, the friction rollers being adjustably mounted so that frictional contact between the respective friction rollers and the travel rings and between the friction rollers themselves is maintained when the spacing between the shafts is varied.

Due to the constant frictional coupling of both cylinders, jolts or deviations from uniform rotation of the cylinders are prevented from having any disadvantageous effects on the printing quality of the press. In accordance with a further feature of my invention, the travel ring mounted on the shaft on which the driving cylinder is mounted has a slightly smaller diameter than the travel ring mounted on the shaft on which the driven cylinder is mounted.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in rotary printing press, it is nevertheless not intended to be limited to the details shown, since various modifications 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 diagrammatic view of part of an offset printing press showing one embodiment of my invention wherein Schmitz rings are mounted peripherally on the plate and blanket cylinders and two friction wheel transmissions are located between the cylinder shafts;

FIG. 2 is another view similar to that of FIG. 1 showing a second embodiment of the invention wherein travel rings are peripherally mounted on the shafts carrying the plate and blanket cylinders, and a pivotally mounted friction wheel transmission is provided between the travel rings; and

FIG. 3 is yet another view similar to those of FIGS. 1 and 2 showing a third embodiment of the invention wherein travel rings are peripherally mounted on the: shafts carrying the plate and blanket cylinders, and a friction wheel transmission located between the travel rings and having two friction wheels, each being mounted so as to be pivotable independently of the other.

Referring now to the drawings and first particularly to FIG. I thereof, so-called Schmitz rings are provided at the axial ends of the plate cylinder 1, the blanket or rubber-covered offset cylinder 2 as well as the impression cylinder 3 of an offset printing press of otherwise conventional construction. The

Schmitz ring 4 of the plate cylinder 1 is about 0.02 mm. greater in diameter than the Schmitz ring 5 of the blanket cylinder 2. Both Schmitz

rings

4 and 5 are raised slightly from one another by displacing the shafts on which the plate cylinder 1 and the blanket cylinder 2 are respectively mounted. The drive for the offset printing press is effected through the impression cylinder 3 in the illustrated embodiment but may, of course, be effected through either of the other two

cylinders

1 and 2.

A pair of friction wheel transmissions 6 and 6' are pressed from both sides respectively into the nip between the plate cylinder 1 and the blanket cylinder 2. One of the transmissions 6 is made up of a compression spring 7 abutting at one end thereof against a stationary bracket 8 secured to the frame of the offset printing press and at the other end thereof against a bearing block 9 on which a pair of friction rollers 10 and 11 are rotatably mounted in mutual engagement at the peripheries thereof, so as to press the rollers 10 and 11 respectively against the Schmitz ring 4 of the plate cylinder 1 and the Schmitz ring 5 of the blanket cylinder 2. The biasing force of the spring 7 can be suitably varied by conventional adjusting means, such as a tensioning screw of the like. The lower friction roller 11, as viewed in FIG. 1, is formed with a diametrically extending elongated bore 12 for mounting the roller 11 on the pivot pin thereof so that it is displaceable thereby toward the upper friction roller 10. Of course, the pivot pin of the friction roller 11 can also suitably be displaceably mounted within a slot formed in the bearing block 9, in which case the bore of the friction roller 11 can be of conventional circular shape as the bore of the roller 10. As can be seen from FIG. 1, the upper friction roller 10 is constantly urged against the Schmitz ring 4 by the spring 7, and the lower friction roller 11 is similarly always pressed against the Schmitz ring 5. Moreover, both friction rollers 10 and 11 are always self-adjustingly in frictional contact with one another at the peripheral surfaces thereof for any change in the spacing between the parallel shafts carrying the plate cylinder 1 and the blanket cylinder 2, respectively.

The Schmitz ring 4 of the driven plate cylinder 1 has a slightly larger diameter than the Schmitz ring 5 of the blanket cylinder 2 which drives the plate cylinder l with the energy transmitted to the blanket cylinder 2 by the driving impression cylinder 3. A slight slippage is accordingly produced between the cylinders l and 2 during rotation thereof, which in turn exerts a force that continuously maintains the working tooth surfaces of the conventional nonillustrated gear wheels or transmission of both cylinders l and 2 in abutment with one another.

The other of the friction wheel transmissions 6' includes a pair of friction rollers 10 and 11' that are mounted independently of one another. The upper friction roller 10', as viewed in FIG. I, is subjected to the biasing force ofa spring 7 in a manner similar to that effected by the spring 7 of the transmission 6, and is pressed at a suitable angle into the nip between the

cylinders

1 and 2 against the Schmitz ring 4 and the friction roller 11 which is rotatably mounted at one end of a bracket pivotable about a fixed pivot pin at the other end thereof. Due to the specific construction of the transmission 6, the spring 7' thereof can be of smaller design as to size and spring force value than the spring 7.

In the embodiment of the rotary printing press shown in FIG. 2, instead of Schmitz rings mounted on the

cylinders

1 and 2, there are provided travel rings or

races

13 and 14 which are fixedly mounted directly on the shafts whereon the cylinders l and 2 are respectively mounted. The travel ring 13 on the shaft for the plate cylinder 1 also has a diameter somewhat larger than that of the travel ring 14 disposed on the shaft for the blanket cylinder 2. The travel rings proper have a diameter that is substantially half as great as the diameter of the

cylinders

1 and 2. A friction wheel transmission 15 is located in the space between the

travel rings

13 and 14. The friction roller transmission 15 is made up of two

friction rollers

16 and 17, whose axes are located in a plane that is inclined with respect to the vertical, as shown in FIG. 2, and are rotatably mounted on a common bearing block 18. The upper friction roller 17 is formed with a longitudinal slot 19 through which a pivot pin fixed to the bearing block 18 extends, so that the upper roller 17 is displaceable in a direction toward the lower friction roller 16.

Coaxially to the rotary axis 20 of the lower friction roller 16, the bearing block 18 is guided in a stationary guide 21, fixed for example to the printing press frame. The bearing block 18 is pivotable about the axis 20 within the guide 21 and is also displaceable in the guide 21 in a direction substantially parallel to the plane in which the axes of the shafts supporting the plate cylinder 1 and the blanket cylinder 2 are disposed. Furthermore, the bearing block 18 is provided with an adjusting arm 22 which is subjected to the biasing force of a suitably mounted compression spring 23. The compression spring 23 tends to urge the bearing block 18 to rotate clockwise, as viewed in FIG. 2, about the pivot pin 20 within the guide 21 which, as seen from the direction of the compression spring 23 is located on the distant side of the plane within which the axes of the shafts for the cylinders I and 2 are disposed. Consequently, the lower friction roller 16 is pressed against the travel ring 14 on the shaft of the blanket cylinder 2, and the upper friction roller 17 against the travel ring 13 on the shaft of the plate cylinder 1. Because of the longitudinally extending slot 19, the friction roller 17 moreover always abuts the friction roller 16 force-lockingly. An arresting device 22 in the form of a set screw is located in the vicinity of the adjusting arm 22'for limiting the lift of the arm 22 resulting from the biasing action of the spring 23. The friction roller transmission 15 is thereby capable of being held in operating position when the cylinders l and 2 have been greatly separated from one another or one of the cylinders l and 2 has been removed from the illustrated assembly.

Also in the embodiment of FIG. 2, as in the embodiment of FIG. I, the friction roller transmission 15 effects a constant abutment of the working flanks of the nonillustrated gears conventionally provided at the ends of the shafts on which the cylinders l and 2 are respectively mounted.

The embodiment of the offset printing press shown in FIG. 3 is a modification of the embodiment shown in FIG. 2. The travel ring 13 on the shaft for the plate cylinder 1 with which the inking mechanism, represented diagrammatically by the inking rollers 25, cooperates, is also of slightly larger diameter than that of the travel ring 14 on the shaft for the blanket cylinder 2. A friction wheel transmission 26 according to my invention is located in the space between the two travel rings 13 and 14, and includes a pair of friction rollers 27 and 28 located above one another and having pivot axis disposed in a plane inclined to the vertical. The lower friction roller 28 always abuts the travel ring 14 of the blanket cylinder 2 and is mounted at one end ofa lever 29 which is pivotable by gravity force about a stationary pivot at the other end of the lever 29 in a direction toward the blanket cylinder 2.

The upper friction roller 27 is carried at one end ofa double lever 30, the opposite end of the double lever 30 being pivotable about a pivot fixed for example to the printing press frame. The intermediate ends of the double lever are pivotally connected to one another. The double lever 30 permits the friction roller 27 to pivot in a direction toward the travel ring 13 mounted on the same shaft as the one on which the plate cylinder 1 is mounted, and also permits linear displacement of the friction roller 27 into the space between both travel rings 13 and 14. An adjusting device 31 in the form of a set screw, for example, acts on the double lever 30 and forces the upper friction roller 27 of the transmission 26 both against the travel ring 13 as well as against the lower friction roller 28 which is, in turn, thereby pressed against the travel ring 14, Instead of the illustrated adjusting device 31, a compression spring, for example, can also suitably be employed.

When the spacing between the axes of the shafts on which the two

cylinders

1 and 2 are respectively mounted is varied, the desired frictional force must be again produced with the aid of the adjusting device 31.

The friction wheel transmissions as well as the travel rings can be provided on the shafts whereon the cylinders l and 2 are respectively mounted, either inside or outside the sidewalls of the printing press.

The use of my inventive transmission is not limited only to the plate and blanket cylinders. In a manner similar to that hereinbefore described and illustrated, the friction roller transmission of my invention can be located between the blan' ket cylinder and the impression cylinder or between any other cylinder pair that is provided for advancing sheets that are to be imprinted. In every case, all the advantageous results of applying pressure to the Schmitz rings are capable of being achieved by the friction roller transmission of my invention, even when there is a change in the spacing between the axes of the shafts on which the respective cylinders are mounted.

Schmitz rings are otherwise known as bearers or cylinder bearers. As aforementioned, they are located at the axial ends of the plate, blanket and impression cylinders. They can be made integral with the drums of the respective cylinders but can also be screwed or bolted to the end faces thereof. Depending upon the compressive load, the Schmitz rings or cylinder bearers are formed of cast iron or hardened steel. For further details regarding the construction and installation of Schmitz rings or cylinder bearers and the operation thereof, reference can be had for example, to U.S. Pat. No. 3,049,996 ofR. H. Downie.

I claim:

1. Rotary printing press comprising a pair of parallel shaft means, each respective shaft means including a rotary printing press cylinder, means for varying the spacing between said shaft means, at least one travel ring carried by each of said shaft means and having a diameter equal at most to the diameter of the cylinder of said respective shaft means, at least one friction wheel transmission located between said shaft means and comprising two friction rollers mutually engaging at the peripheries thereof, one of said friction rollers also peripherally engaging the travel ring carried by one of said shaft means and the other of said friction rollers also peripherally engaging the travel ring carried by the other of said shaft means, and means for adjustably mounting said friction rollers so that frictional contact between the respective friction rollers and said travel rings and between said friction rollers proper is maintained when the spacing between said pair of shaft means is varied.

2. Rotary printing press according to claim I, wherein one of said shaft means comprises a first shaft and a first printing press cylinder mounted on said first shaft, and the other of said shaft means comprises a second shaft disposed parallel to said first shaft and a 'second printing press cylinder mounted on said second shaft.

3. Rotary printing press according to claim 2, wherein said first cylinder is a plate cylinder and said second cylinder is a blanket cylinder.

4. Rotary printing press according to claim 2, wherein said travel rings are substantially peripherally mounted at the ends of said cylinders and are in the form of bearer rings, said friction roller transmission being spring-forced into the nip between said cylinders, said friction rollers being rotatably mounted on a common bearing block, at least one of said friction rollers being mounted with an elongated slot and pin connection for displacement in direction toward the other friction roller.

5. Rotary printing press according to claim 2, wherein said travel rings are substantially peripherally mounted at the ends of said cylinders and are in the form of bearer rings, said friction rollers of said transmission being separately mounted, and including spring means for pressing one of said friction rollers at a give angle into the nip between said cylinders and against the bearer ring on one of said cylinders and against the other of said friction rollers, whereby said other of said friction rol lers is pressed against the bearer ring on the other of said cylinders.

6. Rotary printing press according to claim 2, wherein said travel rings are mounted directly on said first and second shafts respectively above one another and have a diameter substantially half as large as that of said cylinders, said friction rollers of said transmission being disposed above one another with their axes extending into the space between said travel rings in a plane inclined to the vertical, said transmission including a bearing block on which the lower one of said friction rollers is rotatably mounted and the upper one of said friction rollers is mounted both rotatably and displaceably relative to said lower friction roller, fixed guide means wherein said bearing block is rotatable coaxially to said lower friction roller and is displaceable in direction substantially parallel to a plane in which the axes of said cylinders are disposed, and spring means for biasing said bearing block in a clockwise direction about said guide means for pressing said upper friction roller against the upper travel rings, said lower friction roller against the lower travel ring and both said friction rollers against one another.

7. Rotary printing press according to claim 2, wherein said travel rings are mounted directly on said first and second shafts respectively and have a diameter smaller than that of said cylinders so that said travel rings are spaced from one another, said transmission comprising two friction rollers disposed in the space between said travel rings, one of said rollers being mounted on a lever pivotable in a direction toward one of said shafts, and the other of said rollers being mounted on a double lever pivotable in a direction toward the travel ring of the other of said shafts and linearly displaceable into the space between said travel rings, and adjusting means for adjusting said double lever for pressing the respective friction rollers against said travel rings and against one another.

Claims

2. Rotary printing press according to claim 1, wherein one of said shaft means comprises a first shaft and a first printing press cylinder mounted on said first shaft, and the other of said shaft means comprises a second shaft disposed parallel to said first shaft and a second printing press cylinder mounted on said second shaft.

5. Rotary printing press according to claim 2, wherein said travel rings are substantially peripherally mounted at the ends of said cylinders and are in the form of bearer rings, said friction rollers of said transmission being separately mounted, and including spring means for pressing one of said friction rollers at a give angle into the nip between said cylinders and against the bearer ring on one of said cylinders and against the other of said friction rollers, whereby said other of said friction rollers is pressed against the bearer ring on the other of said cylinders.