Roll Formed Flexible Die Plate For Rotary Cutting Tool

Abstract

A method of making a rotary cutting tool for cutting a web of material comprises the steps of roll forming a first flexible die plate into a cylindrical shape, mounting the cylindrically shaped die plate onto a cylindrically shaped fixture, and machining cutting elements onto the roll formed die plate. The roll formed die plate may then be removed from the fixture and attached to a cylinder. The first die plate can cooperate with a second die plate attached to a second cylinder to cut the thin web of material.

Description

RELATED APPLICATION[0001]This application is a 35 U.S.C. §371 national phase application of PCT / US2007 / 060262, filed Jan. 9, 2007, which claims priority benefit of U.S. provisional patent application No. 60 / 757,799 filed on Jan. 10, 2006.FIELD OF THE INVENTION[0002]This invention relates to improvements in rotary cutting tools and more particularly to improvements in flexible die plates for rotary cutting tools.BACKGROUND OF THE INVENTION[0003]Rotary cutting tools are useful for manufacture of carton blanks and other workpieces from sheets or webs of material. In particular, rotary die cutting tools are used in high speed cutting of a moving sheet or web of paper, paperboard, plastics or composite materials. As one example, rotary die cutting machines are used for the high speed mass production of paperboard carton blanks that are subsequently folded into the shape of cartons or boxes such as cereal and cracker boxes, etc. Rotary cutting tools include solid rotary dies, where the cu...

AI Technical Summary

Benefits of technology

[0007]In accordance with a first aspect, a method of making a rotary cutting tool for cutting a web of material comprises the steps of roll forming a first flexible die plate into a cylindrical shape, mounting the cylindrically shaped die plate onto a cylindrically shaped fixture, and machining cutting elements onto the roll formed die plate. The roll formed die plate may then be removed from the fixture and attached to a cylinder. The first die plate can cooperate with a second die plate attached to a second cylinder to cut the thin web of material. Optionally the die plate may be roll formed a second time with a radius generally equal to a...

Problems solved by technology

However, such a design greatly increases the costs of the die cylinders for several reasons, including the cost of the magnets, the cost of machining holes into the cylinders to receive the magnets, and the difficulty in assembly.

There are numerous limitations in the chemical etching process, both in terms of limitations in the properties of the die pates made by the process and difficulties in the process for assembling the die plates to the cylinders.

For example, tool steels (steels with large amounts of non-ferrite alloys) are more difficult to chemically etch.

Chemical etching works better with carbon steels, but carbon steels are relatively brittle and not ideal for forming, bending and other operations.

Also, some geometries such as undercuts are difficult to make.

With regards to the process, use of magnets requires extensive machining of cylinders, thereby making such cylinders quite expensive.

Further, both magnets and welding die plates to the cylinder require extensive changeover time when switching die plates, undesirably increasing downtime for printing.

Known chemically etched flexible die plates are awkward to assemble with the cylinder.

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