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Full text of "Modern Mechanical Engineering Vol-I"

226

THE  MACHINE-SHOP

powerful Cincinnati " manufacturing " machine. The rigidity afforded by
the overhanging arm alone steadies the cutter sufficiently without using the
front brace.

Vertical-spindle Machines.—These (fig. 59) in their broad outlines
suggest the common drilling machines. They have a column, arched above
to carry the vertical spindle, which receives edge or face cutters in its nose,
and is frequently belt-driven. A knee adjustable vertically carries the
work table and slides. Numerous variations occur in the details of these
machines, one of the most valuable being that of adaptation to profiling.

Piano-millers or Slabbing Machines.—These were the latest to
be developed, but they are being employed increasingly. They are built
on the planer model, with a long bed and work table, flanked by vertical
housings, carrying an adjustable cross-rail, with spindle heads. They often
successfully rival the planers, since a single cut is taken over a wide face
during the table travel, instead of requiring a large number of reciprocating
movements. Their utilities are enhanced by the fitting of horizontal
spindles on one or both sides in addition to those on the cross-slide,
sometimes also provided with angular settings, while some machines have
circular tables on the one that reciprocates. The sphere of these machines
lies chiefly in massive work, much of which is arranged in tandem, fre-
quently with the help of fixtures. Edge and face milling are both done,
and a large proportion of gang milling.

Continuous Milling.—This, the last development in this kind of
machining, includes that done on piano-millers, but it is generally understood
to refer to that performed on the rotary tables of vertical-spindle machines,
and is nearly invariably associated with the employment of fixtures. Fig. 60
illustrates a Becker machine machining the inside faces of yoke pieces, em-
ploying two y-in. inserted tooth cutters. Thirty-six pieces are held in the
fixture, and the production is 160 pieces per hour. Connecting-rod ends are
milled on their faces, with pairs of inserted tooth cutters, on a double-spindle
machine. They are set diagonally in place in the fixture to lessen the space
left for " cutting wind ".

DIVISION VI

Reciprocating Machine-tools.—These include the following tools:
(i) The standard planing machine with bed, work-holding table, housings,
and cross-rail, and tool-boxes; the derived machines are: the open-side
planers, pit planers, well planers, portable machines, and key grooving and
broaching machines. (2) The shaping machines having single or double
rams, and tool-heads. The portable shapers are a small group. Gear-tooth
planers are shaping machines of short stroke. (3) The slotting machines, in
which the tools reciprocate vertically, one or two tools being carried in the
ram. The tables are simple, with rectilinear movements, or compound,
to include a circular motion for circular slotting.

Widely though these machines differ, they are properly grouped as

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