GB1574908A - Printing apparatus - Google Patents

Description

(54) PRINTING APPARATUS (71) We, PLASTOTYPE LIMITED, a British company of 56 Stamford Street, London SE1 9LX do hereby declare the invention, for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to printing apparatus, and particularly to a method of attaching a printing plate to a plate cylinder of a rotary printing press or to a base of a fiat-bed printing press.

In conventional rotary letterpress and fiexographic printing, printing plates which can be curved to the periphery of cylinders of various diameters are attached to a plate cylinder, and paper or similar material is continuously fed between the plate cylinder and an impression cylinder.

The printing plates are adhered to the cylinder using an adhesive or a double-sided adhesive tape. This method of attaching the printing plates is acceptable if the plates do not have to be changed very frequently, but if frequent plate changes are required during a printing run, such method is clearly unsatisfactory because of the time wasted in detaching a printing plate and substituting another. A far more satisfactory method would be to use permanently magnetised printing plates on plate cylinders which will accept magnetic attraction. However, because of the need to minimise the weight of the rotating cylinder, plate cylinders are almost exclusively formed of alloys, particularly aluminium alloys, which are non-magnetic. This has previously precluded the use of magnetised printing plates. A similar problem occurs in the attachment of printing plates to nonmagnetic bases of flat-bed presses.

It is an obejct of the present invention to provide a method of attaching a magnetised printing plate to a non-magnetic plate cylinder or flat-bed base.

According to one aspect of the invention, therefore, a method of attaching a magnetised printing plate to a non-magnetic printing plate cylinder or to a non-magnetic base of a flatbed printing press comprises adhering to the plate cylinder or base a laminate comprising a support layer and a layer of magnetically attractable material thereon, and positioning the printing plate over at least part of the laminate so that the printing plate is magnetically attracted to the layer of magnetically attractable material.

It is a further object of the present invention to provide printing apparatus in which a magnetised printing plate can be magnetically attached to a basically non-magnetic plate cylinder or base.

According to another aspect of the present invention, printing apparatus comprises a non-magnetic printing plate cylinder or a nonmagnetic base of a flat-bed printing press; and a laminate adhered to the plate cylinder or base and comprising a support layer and a layer of magnetically attractable material thereon, to which laminate a magnetised printing plate will adhere, in use of the apparatus, by magnetic attraction to the magnetically attractable layer.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a pictorial view of a printing plate cylinder with printing plates attached thereto by the method in accordance with the invention, and Fig. 2 is a sectional detail of Fig. 1.

Referring to the drawing, a non-magnetic printing plate cylinder 1 has adhered thereto a laminated sheet 2 comprising a support layer 3 and a magnetically attractable layer 4.

The support layer is preferably formed of polyester. This provides a very strong backing for the layer 4 and is very resistant to kinking. The support layer is preferably .004 inch thick. The layer 4 is an iron foil, preferably of .002 inch thickness.

The laminate 2 is adhered to the cylinder 1 by means of a double-sided adhesive tape 5, which may be .002 to .010 inch thick, and is preferably .004 inch thick, giving an overall laminate/adhesive thickness of .010 inch. It is preferable to locate the adhesive tape 5 on the cylinder 1 and then apply the laminate 2 to the tape. This avoids the crinkling of the laminate which might occur if the tape 5 were first applied to the flat laminate 2 and the laminate with the tape attached were then bent round the cylinder.

Since the laminate is flexible, it can be wound round a plate cylinder of even quite small diameter, and the whole or any part of the cylinder may be covered with the laminate.

When the laminate has been affixed to the plate cylinder, a magnetised printing plate 6 can be readily attached to the cylinder by magnetic attraction. This provides sufficient adhesion for the printing process to be properly effected, whilst allowing the plate to be easily and instantly removed for substitution of another plate.

Clearly, various modifications can be made without departing from the scope of the invention.

For example, the support layer 3 might be formed of other materials, such as paper. It is not essential for the layer 4 to be formed of iron foil. Other magnetically attractable materials could be used, provided that a strong flexible laminate results.

In place of the double-sided adhesive tape for attaching the laminate to the plate cylinder, a layer of any suitable adhesive applied to the laminate or the cylinder could be used.

Although the invention is described above as applied to a printing plate cylinder, it could also be used in respect of flat-bed presses.

Using the method in accordance with the invention, the conventional non-magnetic plate cylinders and flat-bed bases may be easily converted for use with magnetised printing plates. In the case of a plate cylinder, it may be necessary to reduce the overall thickness of the printing plate by an amount equal to the combined thickness of the laminate and the adhesive, so that the original spacing between the plate cylinder and the impression cylinder can remain unaltered.

WHAT WE CLAIM IS:- 1. A method of attaching a magnetised printing plate to a non-magnetic printing plate cylinder or to a non-magnetic base of a flatbed printing press, comprising adhering to the plate cylinder or base a laminate comprising a support layer and a layer of magnetically attractable material thereon, and positioning the printing plate over at least part of the laminate so that the printing plate is magnetically attracted to the layer of magnetically attractable material.

2. A method as claimed in Claim 1, wherein the laminate is adhered to the cylinder by interposing a double-sided adhesive tape between the cylinder and the laminate.

3. Printing apparatus, comprising a nonmagnetic printing plate cylinder or a nonmagnetic base of a flat-bed printing press; and a laminate adhered to the plate cylinder or base and comprising a support layer and a layer of magnetically attractable material thereon, to which laminate a magnetised printing plate will adhere, in use of the apparatus, by magnetic attraction to the magnetically attractable layer.

4. Printing apparatus as olaimed in Claim 3, wherein the support layer is formed of polyester.

5. Printing apparatus as claimed in Claim 3 or Claim 4, wherein the layer of magnetically attractable material is an iron foil.

6. Printing apparatus as claimed in any one of Claims 3-5, including a double-sided adhesive tape adhering the laminate to the plate cylinder or base.

7. A method as claimed in Claim 1 and substantially as hereinbefore described with reference to the accompanying drawing.

8. Printing apparatus as claimed in Claim 3 and substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. is preferable to locate the adhesive tape 5 on the cylinder 1 and then apply the laminate 2 to the tape. This avoids the crinkling of the laminate which might occur if the tape 5 were first applied to the flat laminate 2 and the laminate with the tape attached were then bent round the cylinder. Since the laminate is flexible, it can be wound round a plate cylinder of even quite small diameter, and the whole or any part of the cylinder may be covered with the laminate. When the laminate has been affixed to the plate cylinder, a magnetised printing plate 6 can be readily attached to the cylinder by magnetic attraction. This provides sufficient adhesion for the printing process to be properly effected, whilst allowing the plate to be easily and instantly removed for substitution of another plate. Clearly, various modifications can be made without departing from the scope of the invention. For example, the support layer 3 might be formed of other materials, such as paper. It is not essential for the layer 4 to be formed of iron foil. Other magnetically attractable materials could be used, provided that a strong flexible laminate results. In place of the double-sided adhesive tape for attaching the laminate to the plate cylinder, a layer of any suitable adhesive applied to the laminate or the cylinder could be used. Although the invention is described above as applied to a printing plate cylinder, it could also be used in respect of flat-bed presses. Using the method in accordance with the invention, the conventional non-magnetic plate cylinders and flat-bed bases may be easily converted for use with magnetised printing plates. In the case of a plate cylinder, it may be necessary to reduce the overall thickness of the printing plate by an amount equal to the combined thickness of the laminate and the adhesive, so that the original spacing between the plate cylinder and the impression cylinder can remain unaltered. WHAT WE CLAIM IS:-

1. A method of attaching a magnetised printing plate to a non-magnetic printing plate cylinder or to a non-magnetic base of a flatbed printing press, comprising adhering to the plate cylinder or base a laminate comprising a support layer and a layer of magnetically attractable material thereon, and positioning the printing plate over at least part of the laminate so that the printing plate is magnetically attracted to the layer of magnetically attractable material.

2. A method as claimed in Claim 1, wherein the laminate is adhered to the cylinder by interposing a double-sided adhesive tape between the cylinder and the laminate.

3. Printing apparatus, comprising a nonmagnetic printing plate cylinder or a nonmagnetic base of a flat-bed printing press; and a laminate adhered to the plate cylinder or base and comprising a support layer and a layer of magnetically attractable material thereon, to which laminate a magnetised printing plate will adhere, in use of the apparatus, by magnetic attraction to the magnetically attractable layer.

4. Printing apparatus as olaimed in Claim 3, wherein the support layer is formed of polyester.

5. Printing apparatus as claimed in Claim 3 or Claim 4, wherein the layer of magnetically attractable material is an iron foil.

6. Printing apparatus as claimed in any one of Claims 3-5, including a double-sided adhesive tape adhering the laminate to the plate cylinder or base.

7. A method as claimed in Claim 1 and substantially as hereinbefore described with reference to the accompanying drawing.

8. Printing apparatus as claimed in Claim 3 and substantially as hereinbefore described with reference to the accompanying drawing.