Patent GB-1215370-A (GB)
Title: Improvements in or relating to the copying of relief patterns
IPC: B29C39/00
Filed: 1968-11-18
Abstract: 1,215,370. Moulding embossing cylinders; seaming non-metallic sheet material. KLEINEWEFERS GRAVUREN G.m.b.H. 18 Nov., 1968 [8 March, 1968], No. 54553/68. Headings B5A and B5K. A mould for casting an embossing cylinder is produced by (1) forming a sleeve from a fabric strip with a relief pattern on one side by bringing the ends of the strip together, and joining them, in end-on abutting contact, to form the sleeve with the pattern on the outside, removing irregularities in the pattern of the joint by adjusting the alignment and/or touching up, (2) turning the sleeve inside out, (3) supporting the sleeve internally in a cylindrical configuration, and building up the outside surface of the sleeve with a thermosetting plastics material to form a rigid cylindrical mould with the relief pattern on its inside surface. The outside of the sleeve may be covered with a web before the application of the building up plastics so as to prevent the penetration of the plastic into the pattern supporting fabric. The ends of the fabric strip may be joined by attaching a joining strip to a first one of said ends on the side opposite to the pattern, supporting both strips by their joined portions, placing the other end of the strip in position abutting said first end over said joining strip and applying heat to the joining strip along its length under the other end of the fabric to fuse the strips together. In an embodiment of the invention, the cylindrical mould is closed at both ends by means of plastics closure discs 14, as shown in Fig. 4. The closure discs have grooves 15 which not only centre the mould cylinder but also prevent moulding material from running out when introduced into the cylinder. The closure discs have also bores 16 for a core tube 17. A funnel 20 is arranged on the upper closure disc through which liquid plastics which later forms the rigid embossing roll cylinder 18 is poured. After hardening the plastics inside the sleeve the outer mould cylinder 13 is removed and the tubular plastic cylinder 18 is slid on a steel mandrel which passes through the core tube of the cylinder to form the embossing cylinder. It is also possible to cast the cylinder directly on the steel mandrel. To facilitate the detaching of the mould, the latter is sprayed on its inside surface before the casting process with, e.g. a silicon oil. In Fig. 2 a piece of patterned fabric 1 is converted into the sleeve by sticking a free edge of the pattern on the free surface of joining strip 2 using a heating device. This device consists of timber beam 4 with a channel section 7 bolted to it and a heat plate 8 which can be reciprocated longitudinally inside channel section 7 by means of a threaded spindle 9 or a cable arrangement. Sticking of the strip 2 to one edge of the patterned fabric can be effected by adhesives or by welding the fabric to strip 2 comprising a plastics film. The patterned fabric is then placed on table top 5 and arranged to form a sleeve with a heating bar on its inside. The edge of the patterned fabric with adhesive strip 2 attached is fixed by means of clumping rods or drawing pins 6 to timber beam 4, the free half of the joining strip 2 being placed over the channel section 7. The opposite free end of the pattern is then placed over the free part of the joining strip 2 and pushed close to the inner edge of the patterned fabric. The heating plate is then pushed against the joining strip and along its entire length. The sleeve is then turned inside out and pulled over an ancillary collapsible cylinder or over a metal tube which is of the same diameter as the embossing cylinder to be made. The outside of the sleeve is then built up by means of a spreader with a thermosetting plastics.