The machine shown in Figs. 1, 2, and 3 has been devised by Messrs.
Junker & Ruh, of Carlsruhe, for cutting internally-toothed gear-wheels.
The progress of the work is such that the wheel is pushed toward the
tool by a piece, n, provided with a curve guide, and that the tool is
raised and separated from the wheel after a tooth has been cut, in order
to allow the wheel to revolve one division further.
The tool is placed in a support, b, which is fixed to the upright,
d, in such away that it may revolve; and this support is connected to
the frame, a, of the machine. A strong flat spring, f, constantly
presses the tool-carrier, b, toward the upright, d, as much as the
screw, g, will permit; and this pressure and the tension of the belt
draw the tool downward. The screws, g, determine the depth of the cut,
and compensate for the differences in the diameter of the tool.
[Illustration: MACHINE FOR CUTTING ANNULAR WHEELS.]
The wheels to be cut are set by pressure into a wrought iron ring, with
which they are placed in a sleeve or support, h. The connection
between the two is assured by means of a nut, c. The axle of the
support, h, is held in the upright of the carriage, k, which
receives from a piece, l, placed on the driving-shaft, n, a slow
forward motion toward the tool, and a rapid motion backward. The
trajectory curve or groove of special form of the piece, l, in which
moves the conducting roller, o, of the carriage, is not closed
everywhere on the two sides, in that the guides that limit it extend
only on the part strictly necessary. This arrangement permits of the
roller being made to leave the trajectory in order that the carriage may
be drawn back to a sufficient distance from the tool when the wheel is
finished, so as to replace the latter by another.
One hollow is cut during each forward travel of the carriage; and, when
such travel is finished, a cam-disk, p, placed on the shaft, n,
lifts the tool-carrier, b, and thus draws the cutting-tool out of the
hollow cut by it, so that the carriage cam can then move back without
restraint. In the interim, the sleeve, h, which supports the wheel,
revolves one tooth through the following arrangement: On the axis, e,
of this sleeve there are two ratchet-wheels, r and s, the number of
whose teeth is equal to that of the teeth to be cut in the wheel. The
wheel, r, produces the rotation of the sleeve, h, and the wheel,
s, keeps the shaft stationary during the operation. The two wheels are
set in motion by a lever, t, or by its click, this lever being raised
at the desired moment on the free extremity of the driving shaft, n,
by a wedge, u. The short arm of the lever, t, engages, through its
point of appropriate shape, with the teeth of the wheel, s, so as to
keep this latter stationary while the tool is cutting out the interspace
between the teeth. When the lever, t, is raised, this point is at
first disengaged from the wheel, s; and the raising of the lever being
prolonged, the button, i, places itself against the upper curve of the
slot in the lever, q, and raises that likewise. q is connected with
the lever, v, which revolves about the axis, e, and v carries the
click, w, so that when the lever, v, is raised, the wheel, r,
turns forward by one tooth. When the lever, t, is lowered, as the
wedge, u, turns more, its click holds the wheel, s, stationary. This
series of operations is repeated until the last interspace between the
teeth has been cut, when the machine stops automatically as follows: A
cam of the disk, A, which receives from the shaft, n, through
cone-wheels, a motion corresponding to that of the wheels, r and s,
abuts against the two-armed lever, z, and this latter then disengages
the rod, y, so that the weight, G, can move the fork, B, in such a way
that the belt shall pass from the fast to the loose pulley.
Motion is communicated to the machine as a whole by the shaft, C, which
is provided with a fast and loose pulley. As shown in the engraving, the
pulley, D, moves the tool, and the pulley, E, causes the revolution of
the shaft, n, through a helicoidal gearing, F.
The construction of the tool carrier is represented in detail in Fig. 3.
The cutting tool, F, rests on a sleeve forming part of the pulley,
r1, against which it is pressed by a nut, while its position is
fixed by a key. The axle, s1, of the tool is held in two boxes, in
which it is fixed by screws. In order that the tool may be placed
exactly in the axis of the wheel to be toothed, and that also the play
produced by lateral wear of the pulley, r1, may be compensated for,
two screws, r2, are arranged on the sides. All rotation of the
shaft, s1, is prevented by a screw, o, which traverses the cast
iron stirrup, C, and the steel axle box.
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