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September, 1925
large hammers the surface speed of the rolls has
necessarily been decreased, while the diameter of
the rolls has been increased, so that the rpm. of the
rolls is much less on large hammers than on small
ones. It is not practicable to increase the diameter
of the pulleys as they would be out of all proportion
to the rest of the hammer, and consequently the belt
speed is much cut down on larger hammers. The belt
tension, particularly at the time of picking up the ram
from a standstill, has exceeded what would be recommended
by belting manufacturers, and this has resulted
in high maintenance cost for the belt By increasing
the belt speed in the manner described in the
new hammer, the effective belt pull is reduced and
the belt can be run at a considerable lower initial tension,
and will not have to be tightened up so frequently,
nor be replaced so often.
Hammer of Massive Construction.
The massive construction of the whole machine
can be readily seen from Fig. 2 better than it can
be described. The new type of hammer has been
brought out by a firm which has a quarter of a century's
experience in building forge shop machinery.
and it is to be expected that they would be familiar
with the fact that this class of equipment is subjected
to abuse and that many of the parts have to resist
stresses which it is practically impossible to compute.
The hammer is design with a liberal factor of safety
and with a further factor of ignorance, to take care of
this condition. Even beyond this, however, the designers
have had in mind that the introduction of the
new type of hammer was an opportunity to design a
machine which could be pointed to for some time to
come as an example of what hammer construction
should be. The castings used are principally of steel.
The shafts, forged parts, gears, etc.. are, for the most
part, alloy or special analysis steel. All rotating bearings
are bushed with fine bearing bronze, cast from
virgin steel. Special attention has been paid to convenient
means of oiling to assure the ample lubrication
and consequent long life of the moving parts.
As will be seen from the photograph, the hammer
has been furnished with box section type frames similar
to those used on steam drop hammers, instead of
the usual I-beam section frames of board drop hammers.
The box section frame is more difficult to make
and more expensive than the I-beam type, but no one
has ever questioned that it is superior since the box
section is the ideal one to resist the strains which, is
the case of a hammer frame, come against it in all
directions.
Novel Guide Construction.
The guides in which the ram operates, Fig. 3, are
of novel design. Drop forgers have expressed the
opinion that this construction could be used to advantage
on all board drop hammers, small as well as
large, ar.d it is expected that this may be developed
in the near future. On the upper half of the frames
there is a single V guide cast integral with the frame.
The bottom half of the guide is a separate piece held
in a pocket in the frame. In the case of the 5000-lb.
hammer, the renewable part of the guide has three Vs
so as to provide ample bearing area. The cross section
of the guide is very heavy in order to prevent
breakage. In this case it is approximately 8 in. square.
Moreover, the guide is strongly reinforced by the
forging-Sfamping - Heaf Treating
331
heavy frame as it is supported in the pocket in the
frame on five sides. The guide is designed to serve
as a renewable wearing piece and, therefore, no adjustment
is provided in the guide itself. As the guide
wears, or after it has been planed down, means are
provided for bringing it out to the proper location by
putting liners back of the guide, between it and the
FIG. 2—Hammer is of the box type construction similar to
that used on steam drop hammers.
frame. The guides are interchangeable from one
frame to another, and can be turned end for end in
the pocket in the frame so that if wear occurs only
at one point, it is possible to change the guides around
until all the available surface has been worn, before
it is necessary to take the guide out and have it
planed.
The ram can be lifted by the rolls in the usual
manner up above the level of the top of the renewable
section of the guide and after the ram has been blocked