Metal deforming – By application of fluent medium – or energy field – With actuated tool engaging work
Reexamination Certificate
1999-02-16
2001-08-28
Jones, David (Department: 3725)
Metal deforming
By application of fluent medium, or energy field
With actuated tool engaging work
C072S061000, C029S421100
Reexamination Certificate
active
06279364
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and apparatus especially although not exclusively for use in hydroforming a tubular member. In particular, this invention relates to a method and apparatus for sealing the end of a tube to be hydroformed.
BACKGROUND OF THE INVENTION
The hydroforming process has application in various manufacturing and industrial processes for manufacturing parts used, for example, in automotive manufacturing, in the aerospace industry, and furniture manufacturing and in other instances where a tubular product formed to very precise dimensions and usually possessing properties of strength and lightness is desired.
A conventional hydroforming press apparatus is taught by Bowman et al. in U.S. Pat. No. 5,233,854. However, such a press apparatus is deficient in that burrs on the edges of the starting material tube can damage the O-rings used for sealing, causing the seal unit to leak. Secondly, the portion of the starting tube material extending from the ends of the dies does not usually form part of the finished product, and accordingly must be trimmed away as scrap material. As a result, the cost of manufacturing increases both in terms of the additional materials cost and the time and equipment required to trim away the excess material.
U.S. Pat. No. 5,235,836 to Klages et al. teaches a seal head for tube expansion having elastomeric rings which are protected against damage from burrs. However, as in the Bowman patent, the sealable portion of the tube extending adjacent the seal head may not match the desired shape of the final hydroformed product and must generally be trimmed away as scrap. Furthermore, the elastomeric rings periodically need to be replaced, thereby increasing manufacturing costs.
U.S. Pat. No. 4,761,982 to Snyder teaches a method and apparatus for forming a tube which eliminates the need for elastomeric rings. In the Snyder patent, a widely flaring bell section is formed in each end of the tube that generally must be trimmed away as scrap.
U.S. Pat. No. 5,475,911 to Wells et al. also describes a hydroforming tool which eliminates the need for elastomeric rings and provides wide outward flares on the workpiece outer wall. However, unless it is desired for the outer wall of the ends of the workpiece to be flared outwards, the ends of the workpiece must still be trimmed away as scrap.
Accordingly, there remains a need for a sealing apparatus which can be applied to an end of a workpiece without the need for using elastomeric rings, and that is adapted to be tailored to match a desired shape of the end portion of the product, and that can seal the net shape or desired shape of the final product, thereby eliminating or minimizing the amount of scrap material which must be trimmed away from the ends of the workpiece for a wide range of end shapes.
SUMMARY OF THE INVENTION
In a first embodiment of the present invention, there is provided a method and apparatus for sealing an end of a tubular workpiece without the need for elastomeric rings, by mechanically conforming the end of the workpiece to the desired shape of the end of the final hydroformed product or as closely as possible to that shape.
In accordance with a first aspect of the invention there is provided a method of sealing an end of a tubular workpiece having an initial transverse cross-section, a wall thickness, an inner surface, an interior region bounded by the inner surface, and a pair of opposite ends, the method comprising the steps of:
providing a sealing tool comprising a neck, and a coining portion comprising a shoulder extending outwardly from said neck;
deforming one of said opposite ends to provide a deformed end portion having a deformed transverse cross-section different from said initial transverse cross-section; and
coining said workpiece by axially pressing said sealing tool into said deformed end portion while pressing said one opposite end laterally inwardly and thereby sealing said deformed end portion.
In accordance with a further aspect the invention provides apparatus for sealing an end of a tubular workpiece having an initial transverse cross-section, a longitudinal axis, a wall thickness, an inner surface, an interior region bounded by said inner surface, and a pair of opposite ends, the apparatus comprising:
a sealing tool including a neck and a coining portion, said coining portion comprising a shoulder extending outwardly from said neck;
an end forming member disposed transversely to said longitudinal axis and including a cavity having a transverse cross-section different from said initial transverse cross-section;
first positioning means coupled to said sealing tool for moving said sealing tool along an axis parallel to said longitudinal axis and for performing a sealing step; and
second positioning means associated with said end forming member for performing a deformation step;
and wherein said deformation step comprises laterally inwardly pressing said end forming member toward one of said opposite ends to define a deformed end portion having a deformed transverse cross-section different from said initial cross-section, and said sealing step comprising coining said workpiece by axially pressing the sealing tool into said deformed end portion while laterally inwardly pressing said deformed end portion.
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Abstract of SU-653-006 Dnepr Metal Inst. “Die for hollow metal blank expansion device” Mar. 28, 1979.
Bestard Thomas E.
Marks Larry D.
Morphy Gary E.
Jones David
Ridout & Maybee
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