CA2169658A1

CA2169658A1 - Method and manufacturing a rotary die cutting machine, and part of such a machine

Info

Publication number: CA2169658A1
Application number: CA 2169658
Authority: CA
Inventors: Per-Olof Ronngard
Original assignee: Individual
Current assignee: STALLINJESTANS LASERFORM AB
Priority date: 1993-08-18
Filing date: 1994-08-18
Publication date: 1995-02-23
Also published as: NO960555D0; SE9302667D0; DE4496063T1; AU7511094A; SE503327C2; SE9302667L; NO960555L; DK171785B1; WO1995005264A1; DK12696A

Abstract

A drum half of wood destined to form part of a wooden drum for a rotary die cutting machine is disclosed. The cutting pattern (3) of the drum half (1) is produced by means of laser beam cutting, and the laser-beam-cut grooves (6) extending in the circumferential direction of the drum half is formed of chain bridges (8) adjacent to the edges of the drum half. In a method of manufacturing a rotary die cutting machine laser beam cutting is used to produce the chain bridges in which 4-mm-long wooden bridges (9) alternate with 4mm-long cuts (10).

Description

-~ W095/05264 PCT/SE9~/00752 21~6~8 fflETHOD OF MANUFACTURING A ROTARY DIE ~U~l~G MACHINE, AND PART OF SUCH A MACHINE

This invention relates to a method of manufacturing a rotary die cutting machine, as well as part of such a machine.
Ba~kylo~d of the Invention In a prior-art method of manufacturing a rotary die cutting r~hine destined to cut e.g. package blanks, a reduced drawing illustrating the design of the package is glued onto a wooden drum. The contours of the drawing are then followed and sawn by hand. However, this method is old-fashioned in many respects, and is neither accurate nor reliable. For instance, the prebored holes, which are needed for introducing the saw blade, prevent the inserted cutting rules from being firmly ret~in~.
In recent years, laser has instead been used for cutting the groove pattern in the wooden drum, such grooves providing a much better grip for the cutting rule.
All cardboard cutting m~.hi n~.~., flat die as well as rotary die cutting ma~h; n~.s, are manufactured with a bridge system, the size of the bridges and their posi-tions on the drum being determin~ when the cutting machines are constructed. This is done in order to eli-minate the "jig-saw-puzzle effect", i.e. to make all the pieces of the drum stick together. The bridges have a length of 8-lO mm.
Problem of the Invention The wooden drum is usually composed of two semi-cylindrical parts. It has, however, been found that not even laser-beam-cut grooves adjacent to the joint between these two parts are able to retain in reliable fashion the cutting rules ext~n~ing in the circumferen-tial direction of the drum, probably because the stresses in the cut drum may act freely at the joint-defining WO95/05264 ~ PCT/SE94/00752 edges of the drum parts. Thus, the cutting rules have shown a tendency to straighten out at the end of the groove curvature adjacent to these edges.
Object of the Invention The object of the invention is to solve the above-mentioned problem.
Sl -~y of the Invention According to the invention, this problem is solved by means of the chain bridges defined in the appended claims and the following description, which replace the prior-art circumferential groove portions adjacent to the joint between the drum halves.
Description of an Embodiment of the Invention An embodiment of the invention is illustrated in the ~c~ompanying drawings, in which Fig. 1 is a plan view of two drum halves, Fig. 2 is a perspective partial view of a drum half which is partly provided with cutting rules, and Figs 2A and 2B are enlarged views of the components framed by ~he~ lines in Fig. 2.
Fig. 1 shows a wooden drum consisting of two drum halves 1. The joint between the drum halves is designated 2. The drum halves 1 are provided with a laser-beam-cut groove pattern 3 for cutting and scoring blanks for two four-point-glued trays of corrugated cardboard. The groove pattern 3 is conventionally produced, such that 8-mm-long bridges 4 remain between the cuts or slits 5.
Cutting steel rules, which have been provided with recesses for straddling the bridges 4, are inserted in the grooves 6 consisting of the bridges 4 and the cuts 5.
According to the invention, those parts of the cir-cumferential grooves 6 that are located adjacent to the drum-half edges defining the joint 2 are broken, i.e.
consist of a chain bridge 8 of 4-mm-long bridges 9 alter-nating with 4-mm-long cuts or slits 10, one such bridge 9 defining the edge of the drum halves.

~ W095/05264 2 1 ~ 9 ~ 5 8 PCTtSE94/00752 At the top of Fig. 2A, an arcuately bent cutting rule ll is completely inserted in a circumferential groove 6, and at the bottom of Fig. 2A, such a cutting rule 12 is but partly inserted in a circumferential groove 6. It is evident from the Figure that the cut-ting rules ll, 12 are recessed at regular 4-mm intervals in the longitudinal direction so as to fit in the chain bridges 8. The chain bridges 8 have a length of about 70-80 mm, but they may have any optional length, depend-. lO ing on the design of the package and its placement on thedie.

Claims

1. A method of manufacturing a rotary die cutting machine with a wooden drum that consists of two semi-cylindrical drum halves, wherein the drum halves (1) are provided with the desired pattern (3) by means of laser beam cutting, and cutting rules (11, 12) are inserted in the cut grooves (6), c h a r a c t e r i s e d in that the grooves (6) to be cut in the circumferential direc-tion of the wooden drum are provided adjacent to the lon-gitudinal edges of the drum halves with such interrup-tions as to produce a chain bridge (8) with wooden bridges (9) of a length of about 4 mm alternating with cuts (10) of a length of about 4 mm, said drum edge being formed of such a bridge (9), and the chain bridge (8) corresponding to the toothing of a cutting rule.

2. A method as set forth in claim 1, c h a r a c -t e r i s e d in that the chain bridges have a length of about 70-80 mm.

3. A drum half of wood destined to form part of a wooden drum for a rotary die cutting machine, c h a r -a c t e r i s e d in that the cutting pattern (3) of the drum half (1) is produced by means of laser beam cutting, and that the laser-beam-cut grooves (6) extending in the circumferential direction of the drum half is, adjacent to the edges of the drum half, formed of chain bridges (8) with wooden bridges (9) of a length of about 4 mm alternating with cuts (10) of a length of about 4 mm.