GB2032537A

GB2032537A - Printing press cylinder bearings

Info

Publication number: GB2032537A
Application number: GB7929971A
Authority: GB
Original assignee: MAN Roland Druckmaschinen AG
Current assignee: Manroland AG
Priority date: 1978-08-29
Filing date: 1979-08-29
Publication date: 1980-05-08
Also published as: BR7905533A; SE7907162L; GB2032537B; JPS5559966A; CH641092A5

Abstract

In a printing press, between an eccentrically bored cylinder bearing bushing (2) and the surface of a bore in the press side frame (4) of a further bushing (2') mounted therein, an intermediate element (5) is interposed, which affords play-free journalling for the bushing in the frame. This intermediate element (5) partly surrounds the cylinder bearing bushing (2) under initial tension and is in the form of a flat tape. Element 5 is made of a highly resistant, extremely wear-proof material having self- lubrication qualities and good sliding characteristics, such as a composition based on polytetrafluoroethylene. <IMAGE>

Description

SPECIFICATION Journalling of eccesntrically bored cylinder bearing bushings of a printing press cylinder This invention relates to the journalling of eccentrically bored cylinder bearing bushings of a printing press cylinder which, for the purpose of changing the position of the cylinder, are so journalled in the side frame of the printing press that they can be rotated to throw in and throw out the cylinder relative to other parts of the press.

In order to be able to print stock of different thicknesses, it is necessary to make the distance between the impression cylinder and the blanket cylinder in offset printing presses variable. For this purpose eccentric journalling of the blanket cylinder is made use of. By throwing the cylinder bearing bushing of the blanket cylinder in or out the distance between the blanket cylinder and the impression cylinder can be varied. The throwing in and throwing out of the bearings may be accomplished in known fashion using a lever or a cam drive.

Journalling of this kind, however, requires a high degree of manufacturing precision, for the journalling of the cylinder bearing bushing in the side frame should be of a construction that is, as far as possible, free of play. For this purpose the blanket cylinder bearings in some machine types are journalled in needle-type roller bearings. This kind of journalling has the advantage that a minimum of play can be achieved, but the limits in this case are determined by the thermal expansion of the bearing. With the tolerances being very close, a temperature change of only a few degrees centigrade may lead to blocking of the blanket cylinder bearing and thus to breaking of the "throwing-off" mechanism.

Needle-type bearings, however, have disadvantages as compared with solid-type bearings, such as small damping, so that for the journalling of printing press cylinders nevertheless solid-type bearings are generally used.

The invention provides ways of journalling the eccentric cylinder bearing bushing in such a manner that play-free journalling between the cylinder bearing bushing and the side frame is obtained, while still enabling the bushing to be turned easily, even if it is actuated only rarely and despite temperature changes.

In accordance with the present invention, there is provided a printing press having a cylinder set on eccentrically bored cylinder bearing bushings journalled in a side frame of the printing press, wherein rotation of the bushings changes the position of the cylinder, and wherein between the bearing surfaces which rotate relative to one another when the cylinder is rotated there is provided an intermediate member in the form of a hollow slit cylinder which extends less than 3600 round the cylinder axis in a plane transverse to that axis.

Journalling of the cylinder bearing bushing in the side frame offers various advantages. Thus, for instance, absolutely play-free journalling of cylinder bearing bushings in the side frame is possible. Changes in the torque caused by the influence of thermal expansion do not exist.

By suitable selection of the material for the intermediate element a shock-dampening effect at the start of printing can be obtained, and stick-slip effects during running can be avoided. Also, there is a minimum of friction, as well as self-lubrication, so the necessity of constant servicing is reduced.

The intermediate member may be located in a number of different positions. For example, it may be on the cylinder shaft and run in an eccentrically bored bearing bushing in turn set in the side frame. Alternatively it may be between two bearing bushings, one of which at least is eccentrically bored, set one inside the other between the shaft and the machine frame.

Alternatively it may be between the bearing bushing(s) and the side frame. It would also be conceivable that the spindle of the plate cylinder would revolve directly in a bearing provided with a coating of material, which coating constitutes the intermediate member.

The invention is illustrated by way of example with reference to the accompanying drawings in which: Figure 1 -shows the journalling of a cylinder bearing bushing in the side frame of a printing press, in section; and Figure 2 is a section view along lines a-a in Figure 1 of the bushing shown in Figure 1.

As can be seen from Figure 1, a blanket cylinder spindle 1 is journalled in eccentrically bored bearing bushings 2 and 2'. The eccentrically bored bearing bushing 2' is journalled in a bore 3 in a press side frame 4. Between the outer surface of bushing 2 and the inner surface of bushing 2' is an intermediate element 5.

The intermediate element 5 is so fabricated that it has a predetermined thickness. This thickness is so determined from the dimensions of bushings 2 and 2' that play-free journalling of the bushing 2 in the bore of bushing 2', is obtained.

The intermediate element 5 surrounds the cylinder bearing bushing 2 only partly, leaving a gap 6 (seen in Figure 2) between its ends, which serves to allow space for the thermal expansion of the intermediate element 5. To facilitate mounting, the intermediate element 5 is chamfered at its ends forming opposed edges of the gap 6 and along its edge facing the cylinder (as seen in Figure 1).

Preferably the intermediate element is so designed that in the region of the gap the cylinder bearing bears with 75 percent of its length upon the intermediate element. This is accomplished by making the gap run obliquely in relation to the cylinder axis.

As material for the intermediate element is highly resistant, extremely wear-proof material with self-lubrication qualities and the ability of very easy sliding is used. This may be, for instance, polytetrafluorethylene with certain admixtures.

In a variant of the embodiment illustrated, the bushing 2' is bored concentrically and only bushing 2 bored eccentrically. In a further variant, bushing 2 is omitted and the intermediate element 5 is interposed between the outer surface of bushing 2, which is eccentrically bored, andthe inner surface of bore 3 in the side frame 4.

Claims

1. A printing press having a cylinder set on eccentrically bored cylinder bearing bushings journalled in a side frame of the printing press, wherein rotation of the bushings changes the position of the cylinder, and wherein between the bearings surfaces which rotate relative to one another when the cylinder is rotated there is provided an intermediate member in the form of a hollow slit cylinder which extends less than 3600 round the cylinder axis in a plane transverse to that axis.

2. A printing press according to claim 1, wherein the intermediate member is located between a single eccentrically bored cylinder bearing bushing and the surface of a bore in the side frame.

3. A printing press according to claim 1, wherein the intermediate member is located between a first cylinder bearing bushing and the surface of a concentric or eccentric bore of a second bearing bushing which is journalled in a bore of the side frame.

4. A printing press according to claim 1, wherein the intermediate member is located between an axial cylinder shaft and an eccentrically bored bearing bushing journalled in the side frame of the press.

5. A printing press according to any one of claims 1 to 4, wherein the intermediate element is under uniform radial compression.

6. A printing press according to any one of claims 1 to 5, wherein the intermediate element is formed of a highly resistant, extremely wear-proof material having self-lubrication qualities and lowfriction surfaces.

7. A printing press having a cylinder journalling arrangement substantially as hereinbefore described with reference to the accompanying drawings.