Metal deforming – By plural tool-couples
Patent
1999-04-22
1999-12-21
Crane, Daniel C.
Metal deforming
By plural tool-couples
72364, 72348, 7240506, 723421, B21D 2230, B21D 3716
Patent
active
060033592
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to deep drawing apparatus used for deep drawing sheet stock, such as a steel sheet, into cup-shaped or bottomed hollow tubular products, and more particularly to index-feed deep drawing apparatus for sequentially deep drawing a long-sized work piece, wound in a hoop, in the longitudinal direction.
BACKGROUND ART
Deep drawing means are publicly known as means for forming cup-shaped containers, for example, from sheet metal. FIG. 4 is a partially cutaway perspective view of a typical process for forming cup-shaped containers using a press mold. In FIG. 4, numeral 101 refers to a punch formed into a cylindrical shape, for example, and vertically movably fitted to a press ram. Numeral 102 refers to a die formed into a hollow disc shape or a hollow cylindrical shape and fitted to a press table in a coaxial manner with respect to the punch 101. Numeral 103 refers to a blank holding pad formed into a hollow disc shape for pressing and releasing a work piece 104 onto and from a die 102 before and after the actuation of a punch 101.
With the above arrangement, a disc-shaped work piece 104 having an initial diameter, D.sub.O, for example, is positioned on the die 102 and forced onto the die 102 with a pushing force, Q, with the blank holding pad 103. As the punch 101 is then forced onto the work piece 104 with a drawing force, P, the work piece 104 is deep drawn into a cup-shaped container having a flange diameter, D. In this way, a metal forming process involving radial drawing of the work piece flange part 104a is called deep drawing. Deep drawing is a useful metal forming process for forming products having small wall thicknesses, such as cup-shaped containers, without generating a large amount of cutting chips as generated in machine working.
FIG. 5 is a longitudinal sectional view illustrating examples of products formed with deep drawing; (a) being a bottomed hollow tubular product, (b) a hollow tubular one with a through hole on the bottom, and (c) a hollow tubular one. The cross-sectional shape of the product may be a quadrangular, hexagonal, or other shape, in addition to a circular shape. The cross-sectional shape and dimensions may be varied at different locations in the axial direction.
DISCLOSURE OF INVENTION
As noted above, deep drawing is a useful metal forming process having an advantage that a long-sized product, having a large axial length size compared with the cross-sectional size, can be formed. When forming such a long-sized product with a single drawing process, however, abnormal local stresses tend to occur at various portions of a work piece 104, causing wrinkles and/or cracks. It is therefore a common practice to carry out deep drawing in multiple steps. Carrying out deep drawing in multiple steps, on the other hand, could accumulate work hardening, depending on the type of material used for the work piece 104, leading to failure of predetermined deep drawing. To cope with this, it has been necessary to anneal the work piece 104 in the middle of the deep drawing.
In deep drawing involving multiple steps, multiple pairs of molds are usually needed; it has heretofore been a common practice that work pieces of a rectangular or disc shape blanked in advance in a separate process are individually charged on the mold manually, and the molded products are also discharged from the mold manually. This involves troublesome and dangerous operations, making it difficult to improve working efficiency. For products of a small size, the complexity of forming operations would increase, leading to increased manufacturing cost.
Furthermore, annealing treatment to reduce or eliminate the aforementioned work hardening would have to be carried out in batches, increasing the amount of work-in-process in manufacturing processes. This would result in complicated process control and increased manufacturing cost.
It is therefore an object of this invention to provide index-feed deep drawing apparatus that can solve the aforementioned problems inherent in the prior art, a
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Futamura Shoji
Murata Chikara
Crane Daniel C.
Institute of Technology & Precision Electrical Discharge Work's
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