GB2116910A

GB2116910A - Impression cylinders for rotary presses

Info

Publication number: GB2116910A
Application number: GB08305979A
Authority: GB
Inventors: Erwin Schwarz
Original assignee: Sulzer Escher Wyss AG
Current assignee: Sulzer Escher Wyss AG
Priority date: 1982-03-25
Filing date: 1983-03-04
Publication date: 1983-10-05
Also published as: IT8320228A0; DE3302091A1; JPS58173660A; GB8305979D0; IT1160823B; IT8320228A1

Abstract

The impression cylinder of a rotary press has a flexible shell (3) consisting of an elastomeric material with high electrical resistance, in which an electrically conductive insert (6) of wire (5) is embedded. The insert (6) is connected to a voltage source (12). The insert may alternatively be in the form of a metal tube and the shell may have an inner layer (7) or an outer layer of insulating elastomeric material. Preferably the shell is supported on hydrostatic bearing elements (8). <IMAGE>

Description

SPECIFICATION Impression cylinders for rotary presses This invention relates to an impression cylinder for a rotary press, the cylinder comprising a flexible roller shelf of elastomeric material supported on support elements; such support elements may be hydrostatic support elements, the cylinder constituting a controlled deflection roll. An impression cylinder of this construction is described in German Patent 25 22 657. The present invention relates to a further development of the described impression cylinder in order further to improve ink transfers during printing.

According to the present invention, an impression cylinder for a rotary press comprises a flexible roller shell of elastomeric material supported on support elements and having an electrically conductive zone beneath the outer surface of the cylinder, the elastomeric material having a high electrical resistance and the zone being connected to a voltage source.

It is already known from UK Patent 604012 and Swiss Patent 470 259 to improve the ink transfer in intaglio printing by providing the impression cylinder with an elastomeric covering of a semiconductor, i.e. a material having high electrical resistance, and electrically charging the covering in a suitable way. The charge may be carried out with DC or AC. According to the invention, the supply of the charge to the elastomeric material of the shell is greatly simplified by using for this purpose a conductive zone in the cylinder which may, in fact, be a component already present for a different purpose in the previously described impression cylinders referred to above. The zone may, for example, be afforded by wire embedded in the elastomeric material of the shell.

Preferably the inside of the cylinder has an electrically insulating layer of an elastomeric material. In such cases the electrical charge is restricted to the shell itself. Alternatively, the electrically insulating layer may be dispensed with and the entire cylinder together with its metal parts can be supported so as to be electrically insulated.

The shell may be provided with an outer layer of electrically insulating elastomeric material. In this case the impression cylinder is suitable for charging with AC, the ink transfer being produced not by direct current flow, but by induction currents.

The invention may be carried into practice in various ways but three impression cylinders embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa section of the first impression cylinder; Figure 2 is a partial section to an enlarged scale of the shell of an impression cylinder similarto that shown in Figure 1 but with a modification; and Figure 3 is a partial section similar to Figure 2 of the shell of a third impression cylinder with a further modification.

The impression cylinder shown in section in Figure 1 comprises a stationary beam 1 which is secured at its ends in a machine frame 2 so as to be non-rotatable. A shell 3 is rotatable about the beam 1 and comprises a layer 4 of an elastomeric material having a high electrical resistance, e.g. 104-106Q, i.e. a semiconductor. A wire 5 is embedded in the layer 4 and is wound helically to form an electrically conductive zone 6 which radially reinforces the shell 3 while its flexibility is retained axially. The inside of the shell 3 shown in Figure 1 is provided with a layer 7 of an electrically insulating and elastomeric material. As will be seen from Figure 1, the shell 3 is supported on hydrostatic support elements 8 after the style of the controlled deflection rolls described in U.S.Patent 3802044. At the ends, the shell is provided with elongate guides 10 which are similar to those described in U.S. Patent 3 885 283.and which allow a rotary movement of the shell 3 about its axis and, at the same time, allow its movement in the pressing plane, i.e. towards or away from a co-acting roller 11, in response to the piston-like support elements 8.

A voltage generator 12 used to charge the shell with a voltage is connected, as shown by arrow 13, to the wire 6. The connection may, for example, be via a slip-ring 14 and a sliding contact co-operating therewith.

The shell 3' shown to an enlarged scale in Figure 2 differs from the shell 3 of Figure 1 only in that it additionally has an outer layer 15 consisting of an electrically insulating elastomeric material.

In the case of the shell 3" shown in Figure 3, the electrically conductive zone 6 is formed by a thinwalled metal tube 16 which is sufficiently stiff in the peripheral direction but is resilient as required in the axial direction.

1. An impression cylinder for a rotary press, the cylinder comprising a flexible roller shell ofelas- tomeric material supported on support elements and having an electrically conductive zone beneath the outer surface of the cylinder, the elastomeric material having a high electrical resistance and the zone being connected to a voltage source.

2. An impression cylinder as claimed in Claim 1 in which the zone is afforded by wire embedded in the elastomeric material of the shell.

3. An impression cylinder as claimed in Claim 1 in which the zone is afforded by a metal tube.

4. An impression cylinder as claimed in Claim 1 or Claim 2 or Claim 3 in which the inside of the shell has an electrically insulating layer of an elastomeric material.

5. An impression cylinder as claimed in any of the preceding claims in which the shell has an outer layer of electrically insulating elastomeric material.

6. An impression cylinder as claimed in any of the preceding claims in which the support elements are hydrostatic support elements and the cylinder constitutes a controlled deflection roll.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Impression cylinders for rotary presses This invention relates to an impression cylinder for a rotary press, the cylinder comprising a flexible roller shelf of elastomeric material supported on support elements; such support elements may be hydrostatic support elements, the cylinder constituting a controlled deflection roll. An impression cylinder of this construction is described in German Patent 25 22 657. The present invention relates to a further development of the described impression cylinder in order further to improve ink transfers during printing. According to the present invention, an impression cylinder for a rotary press comprises a flexible roller shell of elastomeric material supported on support elements and having an electrically conductive zone beneath the outer surface of the cylinder, the elastomeric material having a high electrical resistance and the zone being connected to a voltage source. It is already known from UK Patent 604012 and Swiss Patent 470 259 to improve the ink transfer in intaglio printing by providing the impression cylinder with an elastomeric covering of a semiconductor, i.e. a material having high electrical resistance, and electrically charging the covering in a suitable way. The charge may be carried out with DC or AC. According to the invention, the supply of the charge to the elastomeric material of the shell is greatly simplified by using for this purpose a conductive zone in the cylinder which may, in fact, be a component already present for a different purpose in the previously described impression cylinders referred to above. The zone may, for example, be afforded by wire embedded in the elastomeric material of the shell. Preferably the inside of the cylinder has an electrically insulating layer of an elastomeric material. In such cases the electrical charge is restricted to the shell itself. Alternatively, the electrically insulating layer may be dispensed with and the entire cylinder together with its metal parts can be supported so as to be electrically insulated. The shell may be provided with an outer layer of electrically insulating elastomeric material. In this case the impression cylinder is suitable for charging with AC, the ink transfer being produced not by direct current flow, but by induction currents. The invention may be carried into practice in various ways but three impression cylinders embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure lisa section of the first impression cylinder; Figure 2 is a partial section to an enlarged scale of the shell of an impression cylinder similarto that shown in Figure 1 but with a modification; and Figure 3 is a partial section similar to Figure 2 of the shell of a third impression cylinder with a further modification. The impression cylinder shown in section in Figure 1 comprises a stationary beam 1 which is secured at its ends in a machine frame 2 so as to be non-rotatable. A shell 3 is rotatable about the beam 1 and comprises a layer 4 of an elastomeric material having a high electrical resistance, e.g. 104-106Q, i.e. a semiconductor. A wire 5 is embedded in the layer 4 and is wound helically to form an electrically conductive zone 6 which radially reinforces the shell 3 while its flexibility is retained axially. The inside of the shell 3 shown in Figure 1 is provided with a layer 7 of an electrically insulating and elastomeric material. As will be seen from Figure 1, the shell 3 is supported on hydrostatic support elements 8 after the style of the controlled deflection rolls described in U.S.Patent 3802044. At the ends, the shell is provided with elongate guides 10 which are similar to those described in U.S. Patent 3 885 283.and which allow a rotary movement of the shell 3 about its axis and, at the same time, allow its movement in the pressing plane, i.e. towards or away from a co-acting roller 11, in response to the piston-like support elements 8. A voltage generator 12 used to charge the shell with a voltage is connected, as shown by arrow 13, to the wire 6. The connection may, for example, be via a slip-ring 14 and a sliding contact co-operating therewith. The shell 3' shown to an enlarged scale in Figure 2 differs from the shell 3 of Figure 1 only in that it additionally has an outer layer 15 consisting of an electrically insulating elastomeric material. In the case of the shell 3" shown in Figure 3, the electrically conductive zone 6 is formed by a thinwalled metal tube 16 which is sufficiently stiff in the peripheral direction but is resilient as required in the axial direction. CLAIMS

7. An impression cylinder substantially as described herein with reference to Figure 1 or Figure 2 or Figure 3 of the accompanying drawings.