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is
from the blanking die quite ragged; but a burnishing
operation leaves an edge that was quite comparable
with an expensive machining operation.
Another type of flat work is a reinforcement plate
for holding an automobile hood latch in place. This
part is used in the construction of a popular make of
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FIG. 4—Progressive die used for piercing, countersinking
and blanking.
automobile and is required in large quantities. A compound
type of die is used, this being one that blanks
the piece and pierces all the holes in one operation—a
finished piece being produced with each stroke of the
press.
In Fig. 3 showing the complete die, the upper portion
contains a cutting edge A, which corresponds to
the outline of the blank allowing clearance as in the
plain type of blanking die. The punches B for the
small holes are also in this portion of the die and
after being properly located are held in place by the
punch holder. This punch holder may be readily removed
so that duplicate punches may be inserted as
wear and breakage occur.
FIG. 5—Forming die. In addition to shaping the part, it
shears off part of the stock to give a sharp knife-like edge.
The lower portion consists of the shoe D on which
is mounted the plug E which serves as a punch for the
blank and in addition is the die for the small punches
above. The stripper F removes the strip from the
punch as the press ascends and the knock-out pad G
removes the stamping from the small punches.
Forging- Stamping - Heat Treating
February, 1925
This is a very practical type of die for quantity
production for it is capable of producing upwards of
15,000 pieces daily. To operate satisfactorily the small
holes should be located far enough away from the
edge of the blank — at least once and one-half metal
thickness — so that the die construction will not be
weakened.
Another type of small stamping is the little plate
that serves as the catch for an automobile door lock.
The countersinking required for the wood screws
eliminates the possibility of using the compound type
of die previously described, so that a progressive or
step type is used as shown in Fig. 4. The material,
hot rolled strip steel, is fed into the first operation die
from right to left in strips wide enough for the blank
and allowing sufficient stock on the sides to hold the
strip together after the blank is cut. Otherwise, small
pieces of scrap falling off the strip would clog up the
die and slow up production. A and B are indexing
gauges used in starting the strip which is handled to
the best advantage in eight to 10 foot lengths. A is
held in place on the first stroke of the press, locating
the material for the first step, the piercing of the two
small holes by the punches C. A is then released
and the stop B locates for the countersinking on the
next stroke of the press by the punches D. Then in
the next stroke the blank is cut with the punch E,
roughly gauging from a stop at F and accurately locating
the stock with little pins in the punch which
fit into the countersunk holes before the blank G is
actually cut. At each successive stroke thereafter one
blank is cut, falling through the die and out of the
way, and the piercing and countersinking are performed
on two other portions of the strip.
To finish the plate it is put through another tool
shown in Fig. 5. This is known as a forming die and
in addition to shaping the part actually pinches off a
bit of the stock to give the sharp knife edge required.
After the stamping is formed it is carried up with the
punch on the up stroke of the press and is removed by
a striper plate not shown in the sketch. The press
being inclined the stamping falls away from the tool
of its own accord in time to permit the insertion of
the next blank. A set of tools of this type is suitable
for large production on a very economical basis. The
first operation is capable of producing approximately
20,000 pieces in a 10-hour day and the second operation
approximately 12,000, at a combined cost of considerably
under a cent per piece including material.
(Continued next month.)
Stamping Plant Starts Operations
The Geometric Appliance Corporation, 27 Sixth
fr. ' • Vrooklyn, N. Y., incorporated August 20,
1924, with a capital of $200,000. The company started
business January 2, 1925, and will specialize in the
scientific heat treatment of metals by a special process,
and the manufacture of patented hair curlers,
can openers, surgical instruments and other metal
stamping and die work. Thomas H. Ross, president,
has patented several products to be manufactured,
and has developed the new heat treating process after
-5 years of experimentation. George Macaulay is vice
president, and George E. Nace, secretary-treasurer.