Metal working – Method of mechanical manufacture – Shaping by direct application of fluent pressure
Reexamination Certificate
2000-10-26
2002-09-03
Bryant, David P. (Department: 3726)
Metal working
Method of mechanical manufacture
Shaping by direct application of fluent pressure
C029S432000, C072S055000
Reexamination Certificate
active
06442820
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to hydroforming a tube and, more particularly, to a forming such a tube with an article inserted therein.
BACKGROUND OF THE INVENTION
Hydroforming is well known for its ability to form an integral hollow beam with a complex shape, something which would otherwise have to be fabricated from several pieces and/or bent to shape. Typically, a round tubular blank is inserted between a pair of dies which have an internal cavity in the form of the desired exterior shape of the final part. Then the ends of the tube are plugged and the interior chamber of the tubular blank is pressurized, generally with water or hydraulic fluid, to force it into the shape of the die cavity. The completed part is then de-pressurized and removed.
The hydroformed part often, in its final application, will require that one or more holes or openings to be provided in it, a task which is sometimes accomplished by cutting or drilling after the tube is formed. It is also known, however, to pierce or cut the holes while the tube is still pressurized and held in the die or mold. For example, U.S. Pat. No. 4,989,482 to Mason discloses punching the wall of an internally pressurized tube. Similarly, U.S. Pat. No. 5,666,840 to Shah et al. discloses piercing two aligned holes in a hydroformed tube.
Once the holes are punched, functional elements such as bushings or threaded nuts often must be inserted to permit, say, a fastener to attach to the hydroformed part. Other articles may be required to be inserted. In all cases, however, once the hole(s) have been pierced (or cut, etc.), after the part is removed from the die cartridge, the bushing, etc. is inserted and then welded to the hydroformed part. While other methods of attachment are known, each method requires a separate operation after the part is hydroformed and the hole is cut. Not only do such additional cutting, fitting and welding steps add process cost and time, but also have a tendency to introduce errors such as additional dimensional variation or missed process steps, both of which can be detrimental to the function and economics of the part.
Accordingly, there is a need for an improved method and apparatus for inserting articles into hydroformed tubes which can decrease process cost and time, as well as increase the accuracy and repeatability with which mass manufactured parts are fabricated.
SUMMARY OF THE INVENTION
In a first aspect, the present invention provides 1.A method for hydroforming a tubular member comprising the steps of providing a die having a cavity therein, the cavity having an internal surface corresponding to a configuration of a desired final tubular member, providing a tubular blank; the tubular blank having an internal chamber, confining the tubular blank in the cavity, sealing the internal chamber, pressurizing the internal chamber to cause the blank to conform to the internal surface of the cavity to create the tubular member having a wall, making a hole in the wall of the tubular member while the tubular member is in the die; and inserting an article into the hole while the tubular member is in the die.
In a second aspect, the present invention provides an improved method of hydroforming a tube, the method having the steps of providing a die having a cavity therein, providing a blank having an internal chamber, confining the blank in the cavity, sealing the chamber and pressurizing the chamber to create a hydroformed tube, the tube having a wall, an improvement comprising the steps of, making a hole in the wall while the tube is confined in the die, and inserting an article at least partially into the hole while the tube is confined in the die.
In a third aspect, the present invention provides an apparatus for hydroforming a tubular member comprising a die having a cavity therein for confining a tubular member, pressurizing means for internally pressurizing the tubular member to a desired pressure, a hole-making member for making a hole in a wall of the tubular member and an article insertion member for inserting an article at least partially into the hole wherein the hole-making member is disposed in a passageway in the die, the passageway communicating with the cavity to provide the hole-making member access to the wall of a tubular member confined in the cavity, and wherein the article insertion member is disposed in a passageway in the die, the passageway communicating with the cavity to provide the article insertion member access to a hole in the tubular member while the tubular member is confined in the cavity.
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Bereskin & Parr
Bryant David P.
F & P Mfg., Inc.
Omgba Essama
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