Improvements in Capstan Rest and similar Tool Supports for Lathes and other Machine Tools.
Year: 1897

page_text: Date of Application, 23rd Oct., 1897-Accepted, 2nd Apr.,
1898
COMPLETE SPECIFICATION.
Improvements in Capstan Rest and similar Tool Supports for Lathes
and other Machine Tools.
I, ERNST BECHSTEIN, of 32, Hollmannstrasse, Berlin, in the Empire of Germany,
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:.
The subject of this invention is an arrangement whereby the revolving heads,
usual in the machine tool industry, are enabled to perform, in addition to their
intermittent rotary motion, certain reciprocating or backward and forward move-
ments, with the result that, more especially in automatic slide lathes,-firstly,
the wear of the tools is reduced, and in the next place, a saving of time is effected.
In the accompanying drawings, the improved arrangement is represented, by way
of example, in conjunction with a treble revolving head.
Figure 1 being a longitudinal section of the complete arrangement, and
Figure 2 a plan or top-view thereof;
Figure 3 is a similar plan of the device for imparting rotary motion to the revolv-
ing head.
Figure 4 is a front elevation of the device, and
Figures 5 to 11 illustrate the method of operation.
The slide b, which is positively moved and guided in the frame a, is fitted with
a loose and revolvable boss c, the upper off-set projection or extension d of which
carries the revolving head e; the recesses f being in the usual manner made use
of for the reception of the tools or cutters. While the latter move forward into
their operative position, the revolving head is securely held by a locking device,
the construction of which, being well known, is not specially illustrated here, to
avoid needless complication. During the return movement, this device likewise
operating automatically, releases the revolving head, thereby permitting it to be
set in rotary motion.
The boss c is, on its under side, provided with pins g, the number whereof (here
assumed to be three) is determined by the maximum number of periodical revolu-
tions which the revolving head is desired to perform. These pins g, as the slide
advances or recedes, come into frictional contact with, and are taken round by
the cam-shaped projections of a pawl swinging on its pivot h, which is secured to
the bottom part of the frame; rotary motion being by such means imparted to the
revolving head. Facing the pawl i is a pin 7, subjected to the action of a spring k,
the protruding end of which carries a roller m, which continually presses the free
end of the pawl in such a manner, that the said pawl is always either in the position
indicated in Figure 3, or opposite thereto.
I shall now proceed to describe the process of reversing the revolving motion,
with reference to Figures 5 to 11, illustrating various positions of both the pawl and
revolving head; these figures-with the exception of Figure 8-being plans;
and the position which the revolving head is supposed to occupy in each case being
marked in the said figures by the corresponding position of the pins g, which are
here, for the sake of greater clearness, numbered 1, 2 and 3.
Figure 5 represents an initial position of the revolving head-which is locked

page_text: in its place at the beginning of the forward movement of the slide b (the direction
of which is marked by the arrow I). The pawl is by the action of the pin
forced into the position wherein it is shewn, and pin No. 1 takes up its situation
in contact with the curve or cam surface X' of the projection of the pawl, thereby
swinging round such pawl in the direction of the arrow II, so that the pin is
driven back, and the spring k, compressed. As the carriage slides along on the
rectilinear journey, the several parts of the mechanism assume the positions in
which they are represented in Figure 6. The pawl i has been turned sufficiently
far to enable the pin No. 1 to slide past, while the pin 7 has all but fully entered its
guide.
Figure 7 illustrates a later stage of operation: the slide has moved further along,
15. he result that the pin l, aided by the compressed spring k, presses upon the
curve or cam-surface 2 of the pawl, thereby causing the pawl to return to its initial
position; the curve z¹, meantime, sliding along the pin No. 1 until such pin is fully
released. (This is the position represented in Figure 3).
After the slide or carriage has reached the end of its stroke, it
immediately starts on its return movement and, as it does So, the
revolving head, of course, recovers its freedom to rotate. Now this
rotary motion is imparted to it as a result of the pin No. 1 of the boss, which carries
the revolving head, coming into contact with the front part of the pawl i, which
causes the said boss, as the slide travels further rearward, to revolve in the direction
of the arrow III, Figure 3, the pin No. 1 sliding along the curve 2 of the pawl and
the pin No. 2 taking up its position behind the curve X'. In the meantime the
carriage or slide has completed its backward stroke; the revolving head is, accord-
ingly, once more arrested, and the same process as has been described before is re-
peated, except that now pin No. 2 comes into operation instead of, as before, pin No. 1.
Hence it follows that the revolving head is compelled, as operations proceed,
to perform periodical rotary movement, as frequently as may be desired. Now if
the revolving head be required to accomplish a rocking or reciprocating movement,
the pawl should also move from one side to the other alternately. According to the
present invention, this result is attained by providing the pawl with a second cam-
like projection (Figure 8), against which- as the carriage slides forward-a
bolt S is pressed in such a manner that the pawl is pushed altogether past, or
beyond, the pin 7 (Figure 9), whereby the latter, under the action of the spring k,
is enabled to swing the part right round into the position shown in Figure 10, and
back. The pin, bolt or rod S is operated from the upper side of the revolving head,
being simply so far depressed that it may take up its position behind the projec-
tion p (Figure 8), it being now situated within the diameter of a circle described by
the pins g, and in fact, on the identical radius with one or the other of those pins.
At first, the pawl i is here actuated in the same way as before described, with the
only difference that, the moment pin No. 1 is released from its engagement with
the pawl (Figure 6) the bolt S takes up its position in contact with the curve y¹ of the
pawl (see dotted lines Figure 6), whereby the pawl continues to be turned, until
the point of such pawl has slipped past the pin 7 (Figure 9). Then the cam sur-
face comes into contact with pin No. 2 and is gradually moved by the pin 1 to
the position in which it is represented in Figure 10, until the point of the pawl has
also moved quite past the pin No. 2.
P
As the carriage returns, the revolver arresting device is once more freed, and the
pin No. 2 comes to lie in contact with the pawl,-now locked,- so that the boss must
turn in the manner illustrated in Figure 11, its direction motion being now opposite
to that in which it turned during the forward stroke of the carriage.
In Figure 11 the positions of the several pins 1, 2 and 3, are clearly shewn; and
it will also be seen from the figure how the pin or bolt S acts upon the pawl i
when the carriage performs its next forward journey; for now the bolt s―after the
pin No. 1 (on the right hand side of Figure 11) has moved along the cam surface or
curve X must take up its position against the cam y³ and cause the pawl again to
turn fully past the pin 7 and back to its initial position. Thus, as the machine works
backwards and forwards, an oscillatory or rocking motion of the revolving head will

page_text: take place, so that, in the case of a "compound" revolving head, two tools or cutters
only need be allowed to come into operation, with the useful effects mentioned in the
introductory part of this specification.
The pawl is fitted with a handle t, below, so as to enable it to be reversed by hand,
and thus predetermine the direction of rotary motion of the revolving head-(viz.:
either in the direction of the hands on a clock-dial or in the reverse direction).
It will be readily understood that the pawl, instead of being reversed by the
inserted pin, bolt or rod S, may, if desired be operated automatically by any suitable
or equivalent device, which will suggest itself to the mind of every engineer as a
matter of course; --say, a cam or tappet arrangement, set in operation by suitable
mechanism.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. A tool-holder for machine-tools which in addition to performing intermittent
rotary movements, is adapted to receive reciprocating or rocking motion, owing to
the introduction of a cam arrangement into its operating mechanism substantially
as described.
2. A constructional form of cam arrangement referred to in the 1st Claim, mainly
consisting of a cam-shaped projection (such as p) formed on a pawl (such as i),
against which an inserted bolt, rod or pin (such as $) takes up its position, during
the forward stroke, thereby moving the said pawl past the pin or catch ()-all of
which takes place at the precise moment when the stop pin (9 or No. 1), which lies
in the same plane with the said bolt S, slides past the pawl.
Dated this 23rd day of October 1897.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.