Manufacturing container or tube from paper; or other manufacturi – With cutting – breaking – tearing – or abrading – And with bending
Patent
1991-07-05
1993-01-05
Yost, Frank T.
Manufacturing container or tube from paper; or other manufacturi
With cutting, breaking, tearing, or abrading
And with bending
83 55, 83862, B26F 100, B31B 114
Patent
active
051766132
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The present invention relates to a process and an apparatus for die-cutting and scoring by means of cutting knives and/or scoring rules, of at least substantially flat packaging material which, when being die-cut and scored, has a tendency to crack in the direction of its plane at or near the places where the cutting knives and/or the scoring rules are brought into contact with the packaging material. In the context of the present invention, the term "packaging material" should be broadly interpreted to comprise also display material, for instance, the invention is especially concerned with sheet or strip material, preferably of the type corrugated paperboard or cardboard, and especially laminated material.
TECHNICAL BACKGROUND
In conventional die-cutting and scoring of packaging material, cutting knives and/or scoring rules disposed in a punch are thrust at high speed directly against the unprotected packaging material which is squeezed between the die-cutting/scoring tools and an anvil consisting of either a flat plate (planar die-cutting and scoring) or a rotating cylinder (rotary cutting and scoring). In the latter case, also the cutting/scoring tools are disposed on a rotating cylinder. The cutting knives produce a complete penetration of the packaging material, i.e. a division thereof, whereas the scoring rules which do not penetrate the packaging material completely, produce a permanent deformation and a weakening of the flexural rigidity, i.e. fold lines. Crack-producing forces arise in the packaging material in the direction of its plane, both where complete and incomplete penetration occurs. With present-day technique, these forces often are the cause of an annoying formation of cracks, so that higher grammage, greater strength or thickness of the packaging material is required than would otherwise be necessary. The risk of crack formation increases production costs and restricts the construction possibilities of the packages. In extreme cases, die-cutting and scoring techniques cannot be used at all.
OBJECT OF THE INVENTION
The object of the present invention is to improve upon prior art technique in a simple and inexpensive fashion, such that crack formation, at least to a substantial degree, is prevented.
SUMMARY OF THE INVENTION
According to the invention, this is achieved by a process and an apparatus having the distinctive features stated in the appended claims.
The invention is based on the insight that crack-producing forces which arise to a critical degree the moment the cutting knives and/or the scoring rules come into contact with the packaging material, i.e. when the deformation begins, and in other words impact energy can be absorbed by an intermediate material, such that a crack-reducing effect is obtained in that the packaging material is relieved in the direction of its plane. The crack-reducing material will have the direct contact with the cutting knives and/or scoring rules and thus eliminate the risk that dangerous stress concentrations are produced in the packaging material. It has been found that practically all formation of cracks in the packaging material can be prevented in this way.
It has been found that the choice of crack-reducing material is not critical, the main thing being that the material has such properties that it can absorb impact energy and forces in the direction of its plane, i.e. take up impacts in this plane, at the same time as it does not adversely affect the requisite deformation. The material should be in sheet form and have a certain amount of tensile stiffness and flexural rigidity, and it may advantageously be comparatively thin (foil or film) and thus inexpensive. Usable materials are, for example, paper, plastic and woven material.
Practical tests have now surprisingly shown that the crack-reducing effect is not to any substantial degree impaired if a cutting knife, when executing a cutting movement, passes through a slit in the material, made by a previous cutting movement. This means that one and the same crack-reducin
REFERENCES:
patent: 1080759 (1913-12-01), Gruenberg
patent: 1082985 (1913-12-01), Wilder
patent: 2586744 (1952-02-01), Truth
patent: 3020809 (1962-02-01), Guyer et al.
patent: 3735674 (1973-05-01), Haddock
patent: 4856393 (1989-08-01), Braddon
Cavlin Soren
Edholm Birger
Jones Eugenia A.
Yost Frank T.
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