Creasing device and corresponding method

Abstract

A creasing device (10) for a work unit (11) of a machine (12) for at least creasing and possibly cutting a sheet made of a relatively rigid material, such as corrugated cardboard for packaging, fed in a determinate work direction (F), comprises a first creasing member (32) mounted rotatable with its first axis of rotation transverse to the work direction (F). The device (10) also comprises pre-creasing means (41) disposed upstream of the first creasing member (32) in the work direction (F), and configured to carry out a pre-creasing which progressively deforms the material of the sheet to be worked before it is subjected to the creasing operation proper.

Description

FIELD OF THE INVENTION[0001]The present invention concerns a creasing device, the machine comprising said device and the corresponding creasing method, to carry out at least a creasing operation on a sheet made of a relatively rigid material, such as cardboard, plastic or materials having similar rigidity.[0002]The present invention is preferentially but not exclusively applied to compact machines which, compared to industrial machines, have medium-low productivity and high flexibility above all in managing and working different shapes and sizes of the sheet.[0003]In particular, with the present invention it is possible to make, with the same device, both a blind or continuous creasing and a through or segmented creasing. Here and hereafter in the description, by blind creasing we mean a shaping made with deformation through pressure on the thickness of the material, while by through creasing we mean a shaping in which at least a segment cut through on the thickness is provided.[000...

AI Technical Summary

Benefits of technology

[0023]The present invention causes a more progressive deformation of the internal layers of the creased sheet, particularly in the case of longitudinal creasing where the corrugations are transverse to the work direction, preventing or in any case limiting the explosion of the material. This is also advantageous, however, in transverse creasing, that is, both in a direction parallel to the ridge of the corrugated cardboard, and also in a transverse direction.

Problems solved by technology

One disadvantage of known creasing devices is found particularly in working corrugated cardboard and especially in small-size machines, that is, for small productions, but with great flexibility in working different formats.

Typically, the cardboard is fed with the corrugations transverse to the work direction, also called machine direction, and hence this disadvantage mainly occurs in longitudinal creasing operations, that is, where the axis of rotation of the creasing discs is transverse to the work direction.

In industrial machines, which have much bigger costs, bulk and weight, this phenomenon is limited because large creasing discs are able to perform a progressive creasing and to prevent, or at least reduce, the explosion of the material.

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