Metal deforming – By application of fluent medium – or energy field – Using fixed die
Reexamination Certificate
2000-11-14
2001-08-14
Jones, David (Department: 3725)
Metal deforming
By application of fluent medium, or energy field
Using fixed die
C072S709000
Reexamination Certificate
active
06272894
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to molding techniques, and more particularly to a technique for blow molding a tubular metal part to cause the part to assume a desired shape along at least a portion of the length of the part.
2. Discussion
Various molding techniques are used in a wide variety of applications to form various components, most typically from plastics. One common technique is known in the art as injection molding. With injection molding, a quantity of molten plastic is injected into a mold under pressure. The molten plastic is then allowed to cool. When removed from the mold, the plastic will have assumed the shape of the cavity of the mold.
While molding techniques such as injection molding have proved to be valuable in forming a wide variety of components, until the present time there has been no means for modifying the shape of existing tubular components through conventional molding techniques. Accordingly, up until the present time it has not been possible to take, for example, a tubular, extruded length of metal such as aluminum and form a portion of the metal into an enlarged shape. More specifically, it has not been possible to take a tubular, extruded length of aluminum, which is to form a component of a vehicle article carrier, and to mold the aluminum via the use of a heated molding tool and a pressurized gas such that a portion is enlarged in the shape of an end support. Such a process would permit elongated, tubular lengths of metal such as aluminum to be molded into various complex shapes.
It is therefore a principal object of the present invention to provide a molding process by which a tubular length of material such as aluminum can be modified such that one or more portions of the length of aluminum are formed into a desired, complex shape.
It is still another object of the present invention to provide a method of molding by which a length of tubular metal material such as aluminum may have one or more portions of its length modified to a desired complex shape, without affecting other portions of the length of material which do not need to be modified in shape.
It is still another object of the present invention to provide a method of molding by which a length of elongated, metal material may be quickly and easily inserted into a molding tool which causes one or more portions of the length of material to be enlarged into a desired shape without the need to perform numerous steps in the molding process.
SUMMARY OF THE INVENTION
The above and other objects are provided by a preferred method for blow molding metal parts. The method involves providing a molding tool having first and second portions. Each of the first and second portions includes an access opening in communication with a cavity portion. When the first and second molding portions are placed together, they cooperatively form an access passageway in communication with an internal molding cavity. The internal molding cavity forms a desired shape, such as the outer contour of an end support for a side rail of a vehicle article carrier.
A length of tubular metal material is inserted through the access passageway and into the internal molding cavity of the molding tool. The ends of the metal part are capped or otherwise sealed. The molding tool, having been pre-heated to a relatively high temperature for a predetermined length of time, heats the portion of the metal part residing within the internal molding cavity. A gas under pressure is then injected into the tubular metal part which causes the portion of the part residing within the internal molding cavity to expand and conform to the contour of the internal molding cavity. The molding tool is then allowed to cool before separating the first and second portions thereof and removing the metal part. The finished metal part has a portion which assumes the shape of the internal molding cavity.
In the preferred embodiment the molding tool is heated to a temperature between about 1000° F. and 1200° F., and more preferably to a temperature of about 1130° F. The heating may be accomplished by any suitable means, but is preferably through direct induction heating techniques or electromagnetic induction heating techniques. The gas injected into the tubular part is preferably nitrogen gas under a pressure of between about 400 psi-500 psi.
In an alternative preferred method the first and second portions of the molding tool each include a pair of access openings which both communicate with the molding cavity. When the first and second portions of the molding tool are placed together, a pair of access passageways are formed through which a portion of a metal part may be extended. In this manner a portion of the metal part intermediate the two extreme ends of the part can be molded to assume a desired shape.
The preferred method of the present invention provides a quick, easy and economical means for molding tubular metal parts to assume complex shapes. In particular, the method of the present invention is particularly well suited for molding the end support portions of a side rail of a vehicle article carrier.
REFERENCES:
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patent: 5273707 (1993-12-01), Carroll
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patent: 5960658 (1999-10-01), Hudson et al.
Hudson John
Prichard David Lee
Harness Dickey & Pierce PLC
JAC Products Inc.
Jones David
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