JPS6333457B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blanket cylinder for a sheet-fed offset printing press, of the type having a device arranged in the cylinder groove for tensioning a rubber blanket.

In an offset rotary printing press, a rubber cylinder is used to transfer a printed image from a plate stretched on a plate cylinder to a substrate, such as a sheet of paper, and a rubber blanket is stretched around this rubber cylinder to carry the printed image. There is. In the conventional format, the diameters of the printing cylinder and the blanket cylinder are the same size, and both the printing plate and the rubber blanket are wrapped around almost the entire circumference of each cylinder (Wolfgang Wurenski).
Page 95 of “Introduction to Offset Printing (Einfu¨hrung den Offsetdruck)” by John Walenski,
FIG. 118] Furthermore, an offset rotary printing press is already available in which a corresponding number of rubber blankets are arranged divided around the blanket cylinder in order to transfer a plurality of separate printing images onto the blanket cylinder. It has become publicly known. It is obvious that in this case a corresponding tensioning device is required in the barrel groove for each rubber blanket. An offset rotary printing press of this type is described in Swiss Patent No. 502,897.

The problem of the present invention is also when transferring at least two printed images separated by a non-applied area.
To configure the blanket cylinder of an offset printing machine in such a way that only one rubber blanket can be used that can be stretched on the blanket cylinder, and the tensioning tension of the rubber blanket is approximately equal over the entire winding range. It is in.

This problem is solved by the features of the first claim of the invention.

Due to the arrangement according to the invention of the additional groove with the rubber blanket tensioning device, it is possible to equalize the tension of the rubber blanket both in the central region and at the ends with a relatively simple device. Adjustment is possible, thereby reducing the risk of wrinkle formation due to the uniform tension, among other things.
When contrasted with previously known rubber cylinders which are lined with several circumferential rubber blankets, the rubber cylinder according to the invention offers economic advantages. This is because, instead of the conventional barrel groove, only an additional groove is required under the non-printing area of the rubber blanket, with a simply configured rubber blanket tensioning device; This is because the width of this groove may be smaller than the width of the body groove depending on the case.

Next, embodiments of the present invention will be described with reference to the drawings.

The rubber cylinder 1 is stretched with a rubber blanket 2, which is stretched at its beginning and end by tensioning devices 4 and 5, for example tensioning rods, arranged in the cylinder groove 3. Retained. Additionally, a groove 6 is provided diametrically with respect to this barrel groove 3. Through this groove 6 extends the non-printing area of the rubber blanket 2, which supports two separate printed images A and B. This additional groove 6
A roller 7 is arranged therein, preferably rotatably, which serves as a rubber blanket tensioning device. This roller 7 extends axially through the groove 6 and at both ends of the roller 7 via an axle neck 8.
It is supported by a support portion 9 fixed to the end face side of the rubber cylinder 1. The slot-shaped design of this bearing holder makes it possible to displace the rollers 7 in the radial direction, thereby facilitating the retraction of the rubber blanket and making it possible to vary its tension. The upper part 10 of the bearing 9, which is designed, for example, as a sliding bearing, is removable so that the roller 7 can be lifted out of the groove 6.

If necessary, several rollers can be arranged in the groove 6 instead of only one roller 7, so that the guidance of the rubber blanket 2 can be adjusted in the desired manner and the following can be achieved. It is thus obtained that the tension in the two halves of the rubber blanket supporting the printed images A and B is evenly distributed over the entire circumference of the blanket cylinder 1. A more advantageous configuration is
This occurs because the rollers are held in an additional groove 6 with a spring effect, so that variations occurring in the length of the rubber blanket can be compensated for.

[Brief explanation of the drawing]

The drawing is a schematic side view showing an embodiment of a blanket cylinder of an offset rotary printing press according to the present invention. 1...Rubber cylinder, 2...Rubber blanket, 3...
...Body groove, 4, 5...Tensioning device, 6...Groove, 7...
Rubber blanket tensioning device, 8... shaft neck, 9...
Support part, 10... Upper part, A, B... Printed surface,

Claims (1)

[Scope of Claim] A blanket cylinder for a sheet-fed offset printing machine, comprising:
In a type having a device arranged in the barrel groove for tensioning the rubber blanket, at least two printed surfaces A and B separated by respective non-printing areas in the circumferential direction of the barrel are provided. An additional groove 6 is provided below each non-printing area for tensioning the rubber blanket 2 having an axially extending rubber blanket tensioning device 7. is provided, and the rubber blanket 2 is placed under this rubber blanket tensioning device.
A blanket cylinder of a sheet-fed offset printing press, characterized in that the cylinder extends through an additional groove 6. 2. A blanket cylinder for a sheet-fed offset printing machine according to claim 1, wherein the rubber blanket having two printing surfaces A and B is wrapped around the blanket cylinder 1 in a substantially circumferential direction. . 3. A blanket cylinder of a sheet-fed offset printing press according to claim 2, in which the cylinder groove 3 with the tensioning devices 4, 5 is arranged diametrically with respect to the additional groove 6. . 4. The rubber blanket tensioning device 7 is rotatable and consists of at least one roller arranged axially in an additional groove 6, which roller is fixed on the end side of the blanket cylinder 1. A blanket cylinder of a sheet-fed offset printing press according to claim 1, wherein the blanket cylinder is supported on a bearing part 9 which is attached to the support part 9. 5. The support portion 9 is slidable in the radial direction.
A blanket cylinder for a sheet-fed offset printing machine according to claim 4. 6. A blanket cylinder for a sheet-fed offset printing press according to claim 4, wherein the upper part 10 is removable on the support 9.