Metal working – Method of mechanical manufacture – Work holding
Patent
1995-04-20
1998-01-20
Jones, Eugenia
Metal working
Method of mechanical manufacture
Work holding
83 29, 83451, 83941, 269 21, B26D 701
Patent
active
057090238
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method and apparatus for reducing the working surface area on the cutting table of an automatic machine for cutting a stack of sheet material.
BACKGROUND OF THE INVENTION
Machines for automatic cutting of sheet material (cloth, skins, paper, . . . ), generally comprise a working table on which material to be cut is stacked, a film that is impervious to air covers the stack of material, suction means holds the stack of material down on the table by suction, and a moving cutting tool moves over the stack. For optimization purposes, the working table may itself be constituted by a conveyor that is also designed to transfer the stack.
It happens that some users of such machines need to cut sheets of width that is smaller than the working width of the cutting machine, or sheets that are of standard width but folded in two. During such cutting, a large portion of the cutting table is not covered in material, however the impervious film must nevertheless cover the entire cutting zone in order to provide the sealing necessary for the stack-holding suction. By proceeding in this way, half of the impervious film is used up needlessly, and that is quite wasteful.
An object of the present invention is to solve these drawbacks in satisfactory manner.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved by means of apparatus for reducing the working area for cutting on a cutting machine for cutting a stack of sheet material, the machine being provided with an automatic moving cutting tool and with suction means for holding said stack covered in air-impervious film down on a cutting table, the apparatus being characterized in that it comprises an air-impervious removable mask designed to cover a portion of the table and held in a determined position by fixing and positioning means, together with detection means for detecting the position of said mask on said table and participating in the control of the cutting tool in such a manner as to prevent said mask being cut.
According to an advantageous characteristic of the invention, the fixing and positioning means comprise at least one strip provided with fixing and positioning orifices and secured to the end edge of the mask, and an abutment ensuring that said strip is held in place while the stack is being transferred.
According to another characteristic, the mask includes a porous strip that extends parallel to the boundary edge of the mask with the working surface of the table and said boundary edge is inclined relative to the longitudinal direction in which the stack is transferred.
According to yet another characteristic, the mask is made of a material that is sufficiently flexible to be rolled up in and paid out optionally from a roll disposed on one side of the table.
In a first embodiment, said strip is made in the form of an angle strip fixed to the leading edge of the cutting table relative to the advance direction of the stack, the vertical length of the angle strip forming said abutment.
In a particular embodiment, the detection means comprise sensors that detect the position of the mask and mechanical abutments associated with said sensors to avoid displacements of the cutting tool, thereby avoiding cutting said mask.
In another embodiment, said strip comprises two portions: a first portion secured to a first length of mask and designed to be fixed to the edge of the cutting table; and a second portion secured to a second length of the mask and movable in translation relative to said first portion, being suitable for locking in a position such that said first and second lengths of mask overlap, and said second portion of the strip carries said abutment.
The invention also provides a method of automatic cutting by means of a cutting machine provided with a moving cutting tool for cutting a stack of sheet material that is covered by a film which is impervious to air and that is held down on a working portion of a cutting table by means of suction apparatus, the remaining portion of
REFERENCES:
patent: 3598006 (1971-08-01), Gerber et al.
patent: 3742802 (1973-07-01), Maerz
patent: 3815221 (1974-06-01), Pearl
patent: 4205835 (1980-06-01), Gerber
patent: 4434691 (1984-03-01), LeBlond
patent: 4452113 (1984-06-01), Pearl
patent: 5289748 (1994-03-01), Kuchta et al.
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