AU2001256416B2 - Blanket device with two juxtaposed blankets - Google Patents

Abstract

The invention concerns a blanket device, in particular for a printing machine. Said device consists of two blankets (2, 3) mounted juxtaposed on an impression cylinder. The invention is characterised in that it comprises means for supporting the printing paper in the junction zone of the two juxtaposed blankets (2, 3). The invention is applicable to printing machines.

Description

BLANKET DEVICE WITH TWO JUXTAPOSED BLANKETS The invention concerns a blanket device, in particular for a printing machine of 00 the type with two blankets mounted side by side on an impression cylinder.

In these machines, the blankets are attached at both ends in the gaps made in the peripheral face of the cylinders. In many machines, the gaps are offset by 1800 or 900 in order to minimize the flutter created by passage of the gaps.

n Machines of this type have the advantage of being of simple construction, thus making it possible to have a press manufacturing cost that is lower than for satellite presses. However, they have the great disadvantage that the paper is not held continuously, as it is on the counter cylinder of a satellite press. This can result in a longitudinal fold of the paper, which can cause the paper to break or cause difficulties in folding it, especially if several webs of paper are going into the same folding machine.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

According to a first aspect the present invention provides a blanket device, in particular for a printing machine of the type with two blankets mounted side by side on an impression cylinder, characterized in that it comprises means for supporting the printing paper in the junction zone of the two juxtaposed blankets and in that the adjacent lateral ends of the two blankets are cut along a line that is not parallel to the direction of movement of the paper and in that the cut ends of the two blankets are parallel to each other.

Embodiments of the present invention may provide a blanket device that alleviates the above-mentioned disadvantages.

The invention will be better understood, and other purposes, characteristics, details and advantages thereof will appear more clearly in the following explanatory description, with reference to the WO 01/83235 PCT/FR01/01283 2 appended diagrammatic drawings provided solely by way of example, illustrating several forms of embodiment of the invention, and in which: Figure 1 is a diagrammatic top view of a blanket device according to the invention, and Figures 2 and 5 are more elaborate top views of other forms of embodiment of a blanket device according to the invention.

In figure 1, the reference numbers 1, 2 and 3 designate respectively a web of printing paper and two axially juxtaposed blankets of a printing machine, double width, for example, with a configuration of blanket-to-blanket printing and eight inking units per turn.

The two blankets 2, 3 are mounted side by side on an impression cylinder not represented. The two ends of each blanket are attached in a gap made in the outer peripheral surface of the print cylinder, in a known manner. The gaps are referenced as 4.

The two gaps 4 for attaching the two blankets 2, 3 are angularly offset by 180' or 90' so as to minimize the flapping created by the passage of the gaps.

According to the invention, in order to prevent the web of printing paper 1 from not being held at the junction zone of the two juxtaposed blankets 2, 3, the adjacent lateral ends 6, 7 of the two blankets are cut along a line that is not parallel to the direction of movement of the paper, indicated by the arrow F.

This shape of the lateral ends of the blankets can be obtained in various ways, some of which are represented.

Thus figures 2 and 3 show trapezoidal or double trapezoidal shapes of the adjacent ends of the blankets. In figure 4, the cut line is broken, while figure 5 shows an undulating cut line.

WO 01/83235 PCT/FR01/01283 3 Common to all of the methods of making the cuts of the adjacent ends of the blankets 2, 3 is that the junction zone indicated at 8, in which the paper 1 is not supported by the blankets 2, 3, is relatively small compared to the periphery of the blankets.

The cut of the blankets can be accomplished easily by means of a computercontrolled cutting table. The cutting table ensures perfect parallelism of the cuts of both adjacent edges of the two blankets.

Of course, the cutting of the two blankets will take into account the angular offset of the cylinder gaps for the blankets, while the edges must be assembled so as to constitute a constant space between the two blankets mounted on the same cylinder.

By way of example, in the double trapezoid form of embodiment represented in figure 3, the difference in width of the two sides of the trapezoid could be between I1 and mm, and preferably on the order of 7 mm.

It should be noted that the invention is particularly and appropriately applicable to Journal printing machines in blanket-to-blanket configuration.

It should also be noted that, to improve still more the support effect of the printing paper at the junction of the two blankets, the blanket anchoring gaps made in the cylinder do not extend all the way to the cut end of the blanket, that is, in general they are shorter than shown in figure 1.

Claims (8)

1. Blanket device, in particular for a printing machine of the type with two 00 blankets mounted side by side on an impression cylinder, characterized in that it comprises means for supporting the printing paper in the junction zone of the two juxtaposed blankets and in that the adjacent lateral ends of the two blankets are cut along a line that is not parallel to the direction of movement of the paper and in that the Scut ends of the two blankets are parallel to each other. N

2. Device according to claim 1, characterized in that the cut line has a trapezoidal O 10 or double trapezoid shape. ,I

3. Device according to claim 1 or claim 2, characterized in that the cut line is broken.

4. Device according to claim 1, characterized in that the cut line is undulating.

Impression cylinder for printing machine of the type with two blankets mounted side by side, characterized in that it comprises a blanket device according to any of claims 1 to 4.

6. Impression cylinder according to claim 5, having gaps for attaching blankets to the peripheral surface of the cylinder, characterized in that the gaps do not extend to the junction of the two axially juxtaposed blankets.

7. A blanket device substantially as herein described and with reference to the accompanying drawings.

8. An impression cylinder for a printing machine substantially as herein described and with reference to the accompanying drawings. Dated this eighteenth day of February 2005 MacDermid Graphic Arts S.A. Patent Attorneys for the Applicant: F B RICE CO