Method of producing a stamped item

Details Method of producing a stamped item Method of producing a stamped item

2000-04-14

2001-07-03

Crane, Daniel C. (Department: 3725)

Metal deforming

With cutting

By shearing tool-couple

C072S333000, C072S348000

Reexamination Certificate

active

06253594

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to the stamping of metal products, and more particularly to deep-drawn stamping.
There is a demand for metallic items or parts that are bullet-shaped and hollow, and that include one or more holes in the normally closed end. For example, one such item is a spark plug ground shield
10
(
FIGS. 31-32
) incorporated into a spark plug
20
(FIG.
3
). The ground shield is essentially bullet-shaped and hollow, having a cylindrical side wall
12
and a strap
14
. The strap is integral with the side wall and extends diametrically across the normally closed end of the ground shield
10
.
Typically, the ground shield
10
is fabricated by, first, stamping a metal blank into a bullet shape and, second, machining the closed end to create the strap
14
arcing away from the remainder of the piece. This process is undesirably labor-intensive and therefore expensive and prone to quality and consistency issues.
While at first blush, the ground shield
10
appears to be capable of manufacture using deep-drawn stamping exclusively (i.e. no machining), such manufacture is not possible. Specifically if the strap
14
were formed by piercing the piece, the strap could not thereafter be pulled away from, or arced away from, the remainder of the piece because insufficient metal is left in the strap to withstand such forces.
SUMMARY OF THE INVENTION
The aforementioned problems are overcome in the present invention wherein an elongated, hollow piece having one or more straps over the normally closed end is produced solely using deep-drawn stamping. The process includes the steps of drawing a metal blank into a cup, piercing the bottom of the cup to create a strap in place of the bottom, and reducing the width of the cup without reducing the length of the strap so that the strap arcs away from the remainder of the piece. In the preferred embodiment, the initial forming step is a series of draws and/or redraws to create the cup. And, after the bottom is pierced, the item is reduced in width through a series of push reductions.
Each of the deep-drawn steps is individually known to those skilled in the deep-drawn stamping art. However, the process of the present invention is novel sequence of the steps, enabling the deep-drawn manufacture of a wide variety of parts nor previously possible.
The present invention eliminates the need to machine the pieces following stamping. Consequently, the pieces are produced with less labor and therefore are less expensive. Further, the quality and consistency of pieces is improved.
These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.


REFERENCES:
patent: 1040567 (1912-10-01), Newell
patent: 1712076 (1929-05-01), Hughes
patent: 2086488 (1937-07-01), Batie
patent: 4291567 (1981-09-01), Murayama
patent: 5761949 (1998-06-01), Dalessandro

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