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9,500, 13,000 ami 18,000 lb. respectively. l*or convenience
m manufacturing and transporting, presses
with greater capacities were of the built-up type that
consisted of a base, a frame and an upper housing;
these were secured with four large tie-rods, as shown
in Fig. 6. The latter classification includes machines
having 800, 1000, 1200. 1500 and 2000-ton capacity.
FIG. 6—The built-up frame that made its appearance about
five years ago. The demand for prsses capable of exerting
a greater pressure than the one-piece frame type shown in
Fig. 5 and easy of construction and transportation resulted
in this development. This type of press consisted of a
base, a frame and an upper housing, fastened together by
four large tie-rods. The range of these presses was from
600 to 1,000 tons pressure, the largest machine weighing
65,000 lbs.
The 2000-ton press of the type shown in Fig. 7 weighs
235.000 lb. The modern machine has been renamed
the "squeezing press" due to its varied adaptability
to all classes of work within its range.
Ruggedness of Construction.
These presses are very rugged in construction and
have the appearance of a plain-type punch-press, except
for the knuckle that operates the ram. This
knuckle is coupled to a crank by means of a connecting-rod
or link. As the crank revolves, it straightens
the knuckle. The pressure transmitted to the ram is
many times greater than that which could be produced
through a single-acting direct-connected crank-operated
type of machine. An additional advantage of the
knuckle movement is the application of pressure at
the end of the downward stroke. The position of the
ram at the end of the stroke is controlled by a screwactuated
wedge. This is illustrated in Fig. 8. which
shows the ram in both up and down positions.
Fbrging-Stamping - Heat Treating
May, 1025
Speeding-Up Production.
Increased schedules made equipment for milling or
spot-facing forged arms and levers inadequate. This
need was particularly manifested in brake and equalizer
mechanisms. To meet the increased production,
two ideas naturally presented themselves; first, to increase
the number of the same machines used for the
purpose, and, second, to change the method.
Data relating to coin-press methods were secured.
Some of the heat-treated forgings, made from S. A. E.
Xo. 1045 steel having a Brinell hardness of 197, were
tested under an ( Hsen universal testing machine. This
test determined the load necessary to compress the
part to the desired dimension. The average pressure
required was 163,000 lb. per sq. in. of area. Other
forgings, of S A. F. Xo. 1025 steel having an average
Brinell hardness of 137. required a load of 100.000 Ih.
per sq. in. of area. This gives some idea of the tremendous
force necessary to coin-press parts when the
affected area is of considerable extent.
It was concluded that one press could easily squeeze
to size all of the parts and release the various machines
FIG. 7—A later development of the built-up type of press.
The pressure range of this design is from 800 to 2,000 tons,
the largest machine weighing 235,000 lbs.
on hand for other work. The largest part had an area
of 2-3/16 sq. in. on which a squeezing operation was
necessary. A 400-ton coining-press, having the knuckle
action previously explained, was installed. The finish
allowance required for cutting on each surface was
reduced from 1/16 to 1/32 in. This was found advisable
under the squeezing method. With parts having