Cutting – Processes – With preparatory or simultaneous ancillary treatment of work
Patent
1989-06-19
1991-09-24
Phan, Hien H.
Cutting
Processes
With preparatory or simultaneous ancillary treatment of work
83170, 83171, 83102, 264160, 425289, 425384, B26D 710, B26D 727
Patent
active
050504690
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
Applicant under 35 USC 120 and 35 USC 365(c) claims the benefit of the filing date of International Application PCT/AU88/00409, filed 19 October 1988 and naming the United States as one of the designated states. The present application is a continuation of said International Application.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to effecting cutting or slitting of thermoplastics sheet or foil.
2. Description of the Related Art
SUMMARY OF THE INVENTION
The problem to which this invention is directed relates to a difficulty associated with providing a continuous cutting or slitting of a sheet or sheets of thermoplastics material where such sheet or foil is required to be separate for whatever purpose.
Such purpose might occur, for instance, where the thermoplastics material in sheet form is welded to other sheets and is formed in a plurality of adjacent conduits having integrated water resistant outlet channels integrated therein.
There are efficiencies in forming such channels as a multiple number of channels in adjacent relationship but it then becomes necessary to separate by slitting such conduits one from the other.
There are, accordingly, three sheets of the appropriate thermoplastics material which are welded together and which have to be slit.
It would appear at first sight that all that would be necessary would be to insert a sharp blade at a slitting station and this would be sufficient to effect the slitting as the foil is moved through the slitting station.
Unfortunately, the problem is somewhat more difficult.
A first problem is that any sharpened blade very quickly becomes blunt.
Self-evidently, this is solved by replacing the blade or providing a mechanism by which the blade is replaced on a regular basis but there are costs involved to provide such blades on such a continuing replacement basis and there is furthermore a necessity that the mechanism should be reliable to effect such replacement.
There is, however, a further difficulty in the mere use of a blade.
Because the sheet plastics material can be formed by an extruding process in which the polymer chains may only be approximately aligned in a longitudinal direction, it is found that when a blade is caused to cut on a continuing basis through such sheet, there can be a side tracking effect which can cause substantial misalignment of the slitting location and also can cause undue strain on other parts of an apparatus causing the plastic to pass the slitting station.
Both the life of the cutting blade and the tracking effect can be overcome by providing that the blade, while still sharp, is nonetheless caused to be heated and kept at a temperature so that the cutting effect is combined with a melting effect as the tape engages the blade.
This implicity implies that the blade is made from a thermally conducting material and is heated to such a temperature that such elevated temperature can be rapidly transferred to the approaching plastics material.
One further problem arises, however, in that with a melting of the plastics material, it is found that this causes a substantial build up of material which while partially melted or adhering to parts of the blade, nonetheless accumulate immediately subsequent to the blade and can reach retained quantities that it is necessary, from time to time, to manually clean such materials away from the location.
Apart from the inconvenience from having to constantly monitor such build up, there is the decided difficulty that if it is overlooked at any time such a build up can interfere eventually with the cutting process and can eventually cause a blockage resisting further passage of foil through a slitting station.
According to this invention then, it is proposed that there be located adjacent but behind the first slitting blade, a cooling means whereby to cause resolidification of the plastics material very soon after the slitting action.
The result of this action is to cause such a previously melted plastics material to s
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patent: 3251252 (1966-05-01), Lefevre
patent: 4008720 (1977-02-01), Brinckmann et al.
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patent: 4489630 (1984-12-01), Okada et al.
patent: 4539467 (1985-09-01), Wenger
patent: 4679474 (1987-07-01), Lambrecht
patent: 4783983 (1988-11-01), Narasimhan
patent: 4921563 (1990-05-01), Schwertner et al.
Peterson Kenneth E.
Phan Hien H.
Vinidex Tubemakers Pty. Limited
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