Textiles: fiber preparation – Liberating – Ginning
Reexamination Certificate
1999-07-30
2001-02-06
Worrell, Danny (Department: 3741)
Textiles: fiber preparation
Liberating
Ginning
C019S000620, C083S913000
Reexamination Certificate
active
06182332
ABSTRACT:
APPLICABILITY OF THE INVENTION
This invention relates to a method of forming discrete length fibers, and in particular to a method of forming discrete length reinforcement fibers suitable for use in reinforcement mats, reinforcement preforms, and other types of reinforcement structures.
BACKGROUND OF THE INVENTION
Discrete length reinforcement fibers are useful in the manufacture of many different types of reinforcement structures. For example, the fibers can be used in reinforcement mats for reinforcing articles such as roofing shingles. The reinforcement mats can be made with a single type of fiber, with commingled fibers of different types (e.g., carbon fibers and thermoplastic fibers), or with layers of different types of fibers.
The discrete length reinforcement fibers can also be used in reinforcement preforms. Structural composites and other reinforced molded articles are commonly made by resin transfer molding or structural resin injection molding. These molding processes have been made more efficient by first creating a reinforcement fiber preform that is the approximate shape and size of the molded article, inserting the preform into the mold, and injecting the resin into the mold around the preform.
Discrete length fibers for reinforcement structures are typically formed by cutting a continuous fiber of reinforcement material into discrete lengths. An apparatus for cutting and dispensing discrete length reinforcement fibers is commonly known as a “chopper”. The chopper usually includes a mechanism for feeding the continuous fiber, multiple cutting blades for cutting the fiber into discrete lengths, and a mechanism for dispensing the discrete length fibers. Some choppers allow a change in the length of the discrete length fibers during the cutting operation by changing the speed of the cutting blades relative to the feed rate of the continuous fiber.
A problem commonly associated with choppers is that the cutting blades wear out relatively quickly and must be replaced. This problem is made worse when the speed of the cutting blades is changed relative to the feed rate of the continuous fiber during the cutting operation, because slippage between the accelerating or decelerating cutting blades and the continuous fiber causes increased wear on the cutting blades.
The prior art does not address this problem. For example, published international patent applications WO 95/01939 and WO 96/02475, both assigned to Applicator System AB, disclose choppers in which a continuous fiber is cut between a support roller and a rotary cutter having multiple cutting blades. There is no disclosure of a cutting structure that could reduce the wear on the cutting blades.
Accordingly, it would be desirable to provide a method of forming discrete length fibers that prolongs the lifetime of the cutting blades used in the method. It would particularly be desirable to be able to change the length of the discrete length fibers during the cutting operation without causing increased wear on the cutting blades.
SUMMARY OF THE INVENTION
The above objects as well as other objects not specifically enumerated are achieved by a method of forming discrete length fibers according to the invention. In the method, a first engagement member is moved in orbit relative to a second engagement member. Preferably, the first engagement member is a cutter and the second engagement member is a ring. A continuous fiber is positioned between the first and second engagement members. The continuous fiber is engaged between the first and second engagement members to cut it into discrete length fibers. In a preferred embodiment, the method uses a plurality of first engagement members in cooperation with a second engagement member to form the discrete length fibers.
In another embodiment of the method, a second engagement member is moved in orbit relative to a plurality of first engagement members. A continuous fiber is positioned between the second engagement member and the first engagement members. The continuous fiber is engaged between the second engagement member and the first engagement members to cut it into discrete length fibers.
Various objects and advantages of this invention will become apparent to is those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.
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Eckert Inger H.
Owens Corning Composites SPRL
Welch Gary L.
Worrell Danny
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