Cutting – Processes – During movement of work past flying cutter
Reexamination Certificate
1999-12-22
2001-06-26
Ashley, Boyer (Department: 3724)
Cutting
Processes
During movement of work past flying cutter
C083S698410, C083S346000, C083S669000, C083S331000
Reexamination Certificate
active
06250189
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a rotary die cutter. In one aspect, this invention relates to a die cutting insert for a rotary die cutter and to the die itself. In one aspect, this invention relates to a replaceable or interchangeable die cutting insert or combination replaceable and interchangeable die cutting insert for a rotary die used for cutting absorbent articles from a web of material.
2. Background
Rotary die cutters are used in different industries to cut different types of material. For example, rotary die cutters are used to cut paper, cardboard, plastic, laminates formed of two or more layers, absorbent materials such as wood pulp fluff, webs formed from natural or synthetic fibers, cellulose fluff, tissue, cotton, rayon, and various other types of woven and nonwoven materials.
A rotary die cutter includes a rotatable anvil roll cooperating with a rotatable knife shaft assembly. The knife shaft assembly has an outer circumference and at least one die cutter in the outer circumference of the knife shaft assembly. The knife shaft assembly cooperates with the anvil roll to form a nip through which a web of material can pass. As the web of material passes between the nip, the die cutter cuts the material into a predetermined shape.
INTRODUCTION TO THE INVENTION
Rotary die cutters employ a small nip dimension between the anvil roll and the knife shaft assembly of the rotary die cutter. Because the dimension of the nip between the anvil roll and the knife shaft assembly is very small, the anvil roll and the knife shaft assembly are manufactured to very close tolerances. Because of the close tolerances, most rotary die cutters utilize a solid die shaft having the die cutters integrally formed in the die shaft.
When replaceable die cutting inserts are mounted onto the circumference of a rotatable die shaft, it has been found that it becomes difficult to maintain the required close tolerances. Further, it is difficult to attach the die cutting inserts without also introducing additional forces which cause the inserts to flex under load.
Until now, to assure that the nip dimension remained constant, it was necessary to regrind the die cutting inserts after they were mounted on the knife shaft assembly to assure an accurate nip dimension. The regrinding was particularly necessary when two or more die cutting inserts were mounted about the outer periphery of a die shaft.
Rotary die cutters are used in cutting a plurality of layers of different material assembled to form an absorbent article such as a sanitary napkin or a pantiliner. The absorbent article products are constructed in layers, from top to bottom, of a liquid-permeable cover sheet, one or more absorbent layers, a liquid-impermeable baffle, a layer of garment attachment adhesive, and a removable peel strip. The various layers are bonded together by a construction adhesive, and the article has a total thickness of between about 0.1 inches (2.5 mm) to about 1.0 inch (2.5 cm).
It is an object of the present invention to provide a rotary die cutter apparatus and method providing a rotatable anvil and a rotatable knife shaft assembly with one or more replaceable die cutting inserts mounted to the outer circumference of a die shaft.
It is another object of the present invention to provide apparatus and method including a replaceable or interchangeable die cutting insert or combination replaceable and interchangeable die cutting insert for a rotary die used for cutting absorbent articles from a web of material.
It is yet another object of the present invention to provide a knife shaft assembly and method including a replaceable and/or interchangeable die cutting insert attached to the knife shaft assembly wherein the replaceable and/or interchangeable die cutting insert can be removed from the knife shaft assembly without requiring the inserts to be reground to obtain an accurate clearance nip between the anvil roll and the knife shaft assembly.
A further object of the present invention is to provide apparatus and method providing a replaceable and/or interchangeable die cutting insert which can be removed quickly and easily and/or attached to a die shaft.
Still another object of the present invention is to provide apparatus and method providing a replaceable and/or interchangeable die cutting insert which can be secured easily and properly to a die shaft at a predetermined torque value.
Still further, an object of the present invention is to provide a rotary die cutter apparatus and method providing a rotatable anvil roll mating with a rotatable knife shaft assembly to form a nip between the rotatable anvil roll and the rotatable knife shaft assembly and having one or more replaceable and/or interchangeable die cutting inserts mounted about an outer circumference of the knife shaft for cutting layered absorbent products in large numbers.
Other objects and advantages of the present invention will become more apparent in view of the following detailed description and the accompanying figures of the drawings.
SUMMARY OF THE INVENTION
The present invention provides novel apparatus and method for cutting an article from a sheet material using a rotary die cutter, including providing a die shaft having an outer circumference with at least two die shaft bores, each die shaft bore having a die shaft outer periphery counterbore coaxially formed in the die shaft and respectfully aligned with the die shaft bores. The die shaft outer periphery counterbores are located at the outer circumference of the die shaft. The die shaft outer periphery counterbores relieve stresses in the die shaft imposed by a die cutting insert mounted to the die shaft.
The die cutting insert has an outside periphery, an inside periphery, and first and second spaced apart ends. A knife formed about the outside periphery has a cutting edge and first and second side walls aligned at an angle of at least 15 degrees relative to one another. The die cutting insert is removably attached at the inside periphery to the outer circumference of the die shaft. At least one die cutting insert aperture is formed adjacent to each of the first and second ends and extends completely through the die cutting insert. At least two threaded bolts are sized to mate with the die cutting insert apertures and to secure the die cutting insert to the die shaft bores formed in the die shaft.
The apparatus and method of the present invention preferably include a specified die shaft counterbore depth and structure.
The die shaft counterbores formed on the outer circumference of a rotary die cutter's die shaft and aligned with each die shaft bore formed in the die shaft empirically have been found to relieve stresses in the internal metal of the die shaft as each insert is mounted, interchangeably and repeatedly, to the die shaft in the process of cutting large numbers of layered absorbent articles.
The rotary die cutter apparatus and method of the present invention provide solution for difficulties associated with multiple replacement of cutting die inserts on a die shaft without the need for machining all of the die surfaces to keep the nip constant.
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Ashley Boyer
Connelly Thomas J.
Glantz Douglas G.
Kimberly--Clark Worldwide, Inc.
Parker Thomas M.
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