Improvements in or relating to Lathes for Turning Curved or Spherical Objects.
Year: 1893

page_text: Date of Application, 28th Dec., 1893-Accepted, 7th Apr., 1894
COMPLETE SPECIFICATION.
Improvements in or relating to Lathes for Turning Curved or
Spherical Objects.
I, OTTO ALBERT PETSCHKE, of 28 Augustusburgerstrasse, Chemnitz, in the
Kingdom of Saxony, German Empire, Engineer, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to a new or improved slide rest for use in turning pulleys,
connecting rods, and other curved or spherical objects on a lathe of the usual con-
struction. The slide rest hereby used consists of three slides. the lower one acting.
in a line parallel to the bed, and the other two are cross slides acting transversely
to the line of the bed.
In describing the invention, reference is made to the accompanying drawings in
which
Figs. 1 and 2 are elevations at right angles to each other of my improved slide
rest, and Fig. 3 is a plan of the same.
Fig. 4 is a plan on an enlarged scale of a part of the slide rest shown in the
former figures, and all of these apply to a slide rest. for turning narrow objects such
as pulleys, discs, and the like.
Figs. 5, 7 and 8 are elevations, and Fig. 6 a plan of mechanism applied to rests
suitable for the turning of long objects such as connecting rods and articles of a
similar character.
Fig. 9 is a plan, and Fig. 10 an elevation of an automatic feeding device for the
slide rest; Figs. 11 and 12 are enlarged views of details of the same; and
Figs. 13 and 14 represent outlines of objects turned by the aid of this invention.
The arrangement shown in Figs. 1 to 3 for turning narrow objects consists mainly
of a compound slide rest having a double cross or transverse motion, and a
longitudinal motion actuated from the spindle of the lathe bed, either by mechanical
gearing or by hand in the ordinary manner of lathes, as in Fig. 5. The transverse
notion of the upper or tool slide carrying the turning tool is produced by hand, by
means of the upper screw spindle in the usual manner, while the second cross motion
is automatic and is produced by a slotted link a (secured to the automatic slide) and
an eccentric turning in link a, and the tool slide, being mounted on the automatic
slide, partakes of the movement of the latter.
On the bed plate of the slide rest (Figs. 1, 3,) is affixed a rack g, which
gears in the cog-wheel h. The slide e of the rest carries a vertical bearing d for
the wheel, so that said wheel is attached immoveably to its support but can rotate
on its axis in the bearing and must necessarily follow all movements of the slide e
in a longitudinal direction. A link a, secured to the automatic slide a', resting on
is moved by the rotation of an eccentric b which is on the axle e of the wheel h, and
moves with it; so that the longitudinal motion of the slide e, acting through the
rack upon the wheel h, axle e and eccentric produces the transverse movement
of the link " automatic slide a' (moving in c) and the upper or tool slide a². A
hand lever i is connected with the spindle e and by means of a second eccentric, at
the end of in the bearing d, effects the engaging or disengaging of cog wh: el h
with the rack y in the same manner as the back gearing of many ordinary lathes
are engaged or disengaged. If the slide rest is actuated by the spindle k in a
longitudinal direction, the wheel h partakes of the movement and gearing in the
This
rack y, causes the spindle e to rotate and also the eccentric to move.
eccentric causes such a movement of the turning-tool that by a complete revolution
of the wheel it returns to the same distance from the piece being turned as it was at

page_text: the beginning of the movement. A certain curvature on the piece is the result or
this movement.
Figs. 5, 6, 7, and 8 show the construction of a rest such as is necessary for the
turning of long pieces. The rack g is attached to the lathe-bed below the bearings
and into it gears the spur-wheel , which can be used at the saine time to move the
rest back by hand.. To the spindle n of this spur-wheel is attached a change wheel n¹
such as is used ou turning lathes for cutting threads, and which gears with its
counter-wheel seated on the spindle 7. The transmission of the motion of the
wheel, which is rotated by the rack to spindle 7, is proportional to the size
of these change-wheels. The spindle carries at its other end a bevel wheel r and
to the hub of its counter wheel s is attached an eccentric gearing in the connecting
link fixed to the part m of the slide rest. On the whole slide-rest being caused to
move in a longitudinal direction by the spindle of the lathe, the cog wheel gearing
in rack g rotates and actuates the change-wheels in order to transmit its movement
to spindle and thus make the eccentric rotate by means of the hevelled
gear r, s.
The part m supported by the lower part of the rest will on the longitudinal
movement of the said rest be obliged to make a cross movement, producing a
certain curvature in the piece being turned. The extent of the curvature will
be in proportion to the transmission of the movement of cog-wheel to eccentric b
It is thus possible to regulate the cross-motion of the tool to the longitudinal
movement of the rest, so that for one complete longitudinal movement (due to the
revolution of the wheel ) only one or more rotations of the eccentric are necessary.
The curvature on the turned piece is thus in proportion to the number of the
rotations of the eccentric. Fig. 13 shows the form produced by one rotation of the
eccentric and Fig. 14 the form produced by five rotations to the horizontal
movement.
To operate the rest automatically and to produce a slower rotation of the eccentric,
and consequently a slower cross-motion, a worm and wheel gearing, consisting
of the endless worm and wheel u is used (Figs. 8, 9, and 10). This worm-
wheel u working in the arm w takes up the rotation caused by wheel / through
its spindle n bevel wheels 27, axle Y, and change wheels x, x', transmits it
further to spindley, and thence by means of the bevelled gearing r, s, to the
eccentric carried in the bearing of the part of the slide-rest. A certain
determined cross motion is thus produced.
Figs. 11 and 12 show the support of eccentric in its bearing 1.
This new slide-rest, as described above can not only be used for producing curved
or spherical turning in connecting rods, and other articles as shown, but can also be
most advantageously used for turning other objects, such as reflectors, balls, and
buffer discs.
Having now. particularly described and ascertained the nature of my said inven
tion, and in what manner the same is to be performed, I declare that what 1
claim is;-
1. The herein described method of producing curved or spherical turning on
sliding and surfacing lathes, consisting in effecting the automatic forward and
backward motion of the transverse slide rest carrying the tool at the same time as
the forward motion of the longitudinal rest, and operated from the same by means
of suitable intermediary organs, substantially as herein described with reference to
the accompanying drawings.
2. In compound slide rests for turning lathes the combination of the bed
plate frack g, cog-wheel and eccentric & and means for operating the same,
substantially as and for the purpose herein described with reference to the
accompanying drawings, Figs. 1, 2, and 3.
3. In combination with a turning lathe, and slide rest therefor, a rack y, a cog-
wheel h, shaft bearing a change wheel, gearing into a wheel seated on the
spindle q, a bevel gearing r, s, actuating an eccentric and means for operating the

page_text: same, substantially as and for the purpose herein described with reference to
the accompanying drawings, Figs. 5, 6 and 7.
4. For automatically effecting the backward and forward motion of the slide rest
herein described, the combination of worm gearing u, d, shaft n, bevel gearing e,
change wheels, a', bevel gearing r, s, eccentric band means for operating the same
substantially as and for the purpose herein described with reference to the
accompanying drawings, Figs. 8, 9, and 10.
Dated this 28th day of December 1893.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.