Improvements in Stop Mechanism for Cutting or Turning Machines.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Stop Mechanism for Cutting or Turning Machines.
We, THE HOFFMANN MANUFACTURING COMPANY, LIMITED, and ERNST GUSTAV
HOFFMANN, Engineer, both of 43, Beech Street, Barbican, London, E.C., do hereby
declare the nature of this invention to be as follows:-
In operating certain machines or apparatus such as lathes or machines having
cutters which are presented to rotating bodies it is sometimes desirable to provide
means whereby the machine may be stopped immediately should anything interfere
with the proper operation of the cutters or the like.
In order to provide for this contingency a stop mechanism of some kind is desirable
and the present invention consists of an arrangement of this kind which has been
specially designed for use with an automatic machine for cutting balls or the like
from a rotating wire by means of a reciprocating cutter. The invention however
is applicable to machines of a similar nature in which it is necessary to provide
an automatic stop for a reciprocating part.
The stop mechanism according to the present invention consists of a species of
spring buffer connecting the cutter slide through a suitable arm with the operating
mechanism which may be a lever worked by a cam, the buffer being interposed in
such a way that the slide is not driven positively but only through the pressure on
the spring in the buffer device so that the action of the device relies entirely upon
the yielding of the spring.
Such spring may be contained in a housing provided with devices for adjusting
same and with journals suitably held in bushings embraced by a yoke of the slide
arm.
In the housing and against the spring works a connecting rod attached to the
lever above referred to such rod carrying at right angles or approximately at right
angles thereto a loose removable rod which carries in turn a removeable capped
pin passing through a cam slot in the connecting rod. Both ends of the loose
rod preferably project from the connecting rod at the side passing through the
journals of the housing suitably hung at a point where it may be pushed aside, or
moved by one end of the rod is a bar rod or stop which may be pivoted to a lever
connected in some suitable way with a clutch or belt shifting device so that when
the stop is moved the particular device employed will be operated and the machine
or part of same duly stopped.
In its general operation the connecting rod working in the housing will not
compress the spring as long as the cutter performs its work properly until it has
moved the loose rod carried by same past the stop when said rod through the pin
and can slot will be forced outwardly from the housing such operation being the
effect of a final act on the part of the cam required in the particular cutting operation***
to which this device has been specially adapted. It need not however effect this
movement and it may thus be said that the slide is moved under normal conditions.
without compressing the spring but as soon as there is any interference with
the movement of the cutter the spring is compressed and the rod forced out against

page_text: the stop device which thus operates the belt shifter or clutch, the stop being so
formed that the rod may strike it at any point between the beginning and end of
the operation of the cutter so that it may be moved should an obstruction occur at
any point of the operation in the checking movement, caused by the obstruction
being multiplied in effect by the arrangement of the parts so that the rod will
operate with a very slight obstruction of the cutter.
If the rod has been operated in the outward movement for instance of the lever
the return movement will through the pin and cam slot cause it to be withdrawn out
of the path of the stop device before the general backward movement takes
place.
If necessary the stop device may be provided with a micrometer adjustment to
render it more sensitive.
Dated the 18th day of February 1800
We, THE HOFFMANN MANUFACTURING COMPANY, LIMITED, and ERNST GUSTAV
HOFFMANN, Engineer, both formerly of 43, Beech Street, Barbican, London, E.C., but
now of Chelmsford, in the County of Essex, 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 :--
In operating certain machines or apparatus such as lathes or machines having
cutters which are presented to rotating bodies it is sometimes desirable to provide
means whereby the machine may be stopped immediately should anything interfere
with the proper operation of the cutters or the like.
In order to provide for this contingency a stop mechanism of some kind is desirable
and the present invention consists of an arrangement of this kind which has been
specially designed for use with an automatic machine for cutting balls or the like
from a rotating wire by means of a reciprocating cutter. The invention however is
applicable to machines of a similar nature in which it is necessary to provide an
automatic stop for a reciprocating part.
The stop mechanism according to the present invention consists of a species of
spring buffer connecting the cutter slide through a suitable arm with the operating
mechanism which may be a lever worked by a cam the buffer being interposed in such
a way that the slide is not driven positively but only through the pressure on the
spring in the buffer device so that the action of the device relies entirely upon the
yielding of the spring.
One form of my invention is illustrated in the accompanying drawing in
which
Fig. 1 is an elevation shewing a general view of the mechanism operating a slide
carrying a circular cutter.
and
Fig. 2 is a plan of the spring buffer and stop device partly in section.
Fig. 3 is a similar view with the parts in another position.
Fig. 4 is a side sectional elevation of the spring buffer on line y-y, Fig. 2,
Fig. 5 is a cross section of Fig. 4 on line z-z of same and looking to the left the
central part or connecting rod being in elevation and the top device being shown in
addition also in elevation.

page_text: The mechanism is shewn in these drawings adapted to the automatic ball making
machine previously referred to and from same its adaptation to other devices will be
readily understood.
In the operation of this machine, it was of importance to provide means whereby
the machine would be stopped immediately should anything interfere with the
proper working of the cutters, or should the wire be at an end. In order to make
such mechanisin practical and positive the stop mechanism is so arranged that the
action of the cutter itself reacts upon the same directly. The adaption of this
stop mechanism to the machine in question also had in view the possibility of
making the machine stop when the balls increased in diameter by a very small
amount, which increase is possible when the cutters have become dull.
a is a pivoted lever which drives the slide a upon which the cutter a² is
mounted. b is the connecting rod which transmits motion from the cam bl
through a crank 62 to the cutter slide and between a and b the stop mechanism
is interposed. b is a spring to withdraw the connecting rod b. c is a housing
containing a spring c against which the connecting rod presses, a reduced end 63
of said rod acting to guide both rod and spring. d d are projections forming journals
upon c for the purpose of mounting it moveably in lever a. m is a cap on the
housing and n a lock nut. Bushings e e fit upon the projections d d and form
bearings within which the housing c swivels. This construction of bushings e has
been adapted merely to provide means for the quick removal of the stop motion from
lever a.
It will be noticed that the lower end of lever a has a yoke the ends of which
are slotted, so that as soon as bushings e are withdrawn sidewardly the journals & d
and housing c can drop out of the lower end of lever a, passing through the said
slots. Said bushings e c are held in position by a screw on either side (see Fig. 1).
In line with the axis of the journals d d a hole is formed in which is a rod g capable
of moving freely longitudinally, said rod y also passing through a slot j in rod b. A
small pin passes at right angles through rod g and also through connecting rod b
and housing c and where such pin h passes through the connecting rod b, said
connecting rod is provided with a slot k, which in this case answers the purpose of a
cam, while a slot is also formed in the housing c to allow the pin to move
therein.
As soon as the spring c¹ is compressed, which will happen when the lever a is
prevented from moving to the left in consequence of the cutter slide being hindered
in its forward movement, the cam slot will force small pin hand with it the rod
endwise as shown in Fig. 2.
The pin his fastened into a cap which is provided to prevent any oil or chips
from the machine dropping into the interior of the stop mechanism such cap covering
the slot in the housing c. The nut m is provided for adjusting the pressure of
spring c. The stop device consists of a lever o having a T head o¹ and mounted
upon shaft p and capable of rocking same and acts in connection with rod g in the
following manner :-In Fig. 2 the stop mechanism is shown when the cutter slide
has ceased its forward movement because it has reached its full stop, but the cam b¹
still imparts motion to said connecting rod, which in turn compresses the spring c¹.
It should be understood that in the construction shown in the drawing spring c¹ yields
by being compressed at each revolution of the cam by reason of a lump 6x which is
formed on said cam and the purpose of which will be hereafter explained. Such
compression of spring c¹ permits connecting rod 6 to be further pushed into the
housing c and therefore causes the cam slot k to effect a sideward movement of rod g
through the medium of pin h.
One end of rod g protruding beyond its hole acts upon lever o under certain cir-
cumstances. When the cutters properly perform their work the outward movement
of rod g Fig. 2 only takes place after it has passed head o¹ of lever o, but should the
free forward movement of the cutter be interfered with and therefore the spring c¹ be
meeting with greater resistance than it can bear, its compression will take place
sooner, and the rod g will be forced outwardly before it has cleared the end of head o¹.

page_text: In this case the lever o will be pushed away to a sufficient extent to rock shaft p and
act upon an escapement, which permits the belt to go on the loose pulley or to open
a friction clutch on the machine as the case may be. In either case the machine
will be immediately stopped.
In its normal position the rod g will hardly protrude at all beyond the journal end
and therefore it will pass clear of same. In such normal position the rod g has a
further object, namely, to prevent the connecting rod b being pushed too far outward
by spring c because such rod g will come in contact with the end of slot j in rod b
which provides for a limited movement of said rod g within rod b. Fig. 3 shows the
position when rod g is not protruding and is passing head o¹ as is the case during the
ordinary cutting operations.
It will be seen that any interference with the normal forward motion of the cutter
is bound to react upon spring c¹ which cannot stand the increased resistance and
therefore no matter what the relative position of the stop mechanism as regards
head o¹ of lever o may be, it is bound to act upon said lever by means of rod g unless
indeed the whole mechanism has been moving to the left, as far as is necessary to
permit rod g to clear the edge of head o¹ in which case only, lever o will not act upon
the belt shifter or the like and therefore the machine will be kept going.
The small pin h can be withdrawn by means of cap 7 and therefore rod g can also
be withdrawn by means of its knurled end g' and hence these parts can be subjected
to examination and repaired in a few moments without requiring the taking apart of
other parts of the machine.
Rod where it strikes head of is hardened, as is also the striking surface of the
head o¹. As soon as the return movement of the parts sets in, the first action of the
connecting rod b going backward will be to move rod g inward, until it has reached a
position to clear head o¹ and only then will all the parts move backward together as if
they were one solid piece.
The lever o can be adjusted upon its shaft p in such a manner that it will be very
sensitive and together with the fact that lever a transmits motion and power to the
cutter slide which it drives in proportion of say about 1 to 4 it follows that the
retardation of the cutter by only one thousandth part of an inch will multiply
to the four thousandths part of an inch at rod g, or in similar proportion according to
the relative lengths of lever a.
By the foregoing it will be clear therefore that should the cutter for instance strike
the wire or the like from which the articles are being formed when the latter does not
revolve in consequence of its having run so short that its clutch or holding
device cannot hold it any longer the cutter will be prevented from penetrating into
the wire and therefore causes spring c¹ to yield, which yielding sets in motion
rod
and lever o which latter acts upon the belt shifter which shifts the belt from
the face of the fast to the loose pulley or opens the friction clutch as the case
may be.
Should the cutter have become so dull that it has difficulty in entering the
wire, and that the spring does not suffice to take care of the increased resistance it
will therefore yield with the same result, namely, the rod g will be set in motion
forcing away lever o which latter causes the machine to stop.
If necessary lever o may be provided with a micrometer adjustment, so as to make
it more sensitive, and therefore the slightest increase in diameter of the articles
operated upon by the cutter resulting from dullness of the same, or the increased
hardness of the material will cause the machine to stop.
It has also been found that in case the oil lubricating the cutting operations should
fail to circulate for a few moments such an event is also likely to cause the machine to
stop, because the cutter cannot penetrate the wire the same way as it can when well
lubricated, and therefore if spring c¹ is very delicately adjusted it must yield with
the result that rod g is pushed out and connecting lever o stops the machine.
If we now consider the functions of the cam 61 as shown and provided with the
lump b it will be seen that, assuming the cutter does meet with the obstruction
while the cam has actually travelled the entire length of its circumference except

page_text: that portion occupied by the lump, and just at that point the cutter still meets with
an obstruction which prevents it from going right home to its normal limit such
obstruction, encountered even as late as that, will cause the machine to stop because
the lump left on the highest point of the cam is of sufficient height to compress the
spring c¹ far enough and therefore to move the rod g endwise a sufficient amount to
effect the stoppage. The obstructions the cutter can meet are numerous. Among
the most cominon are dullness of cutter requiring more pressure than the spring c¹ is
set for, or momentary insufficiency of the oil supply, causing the cutter to penetrate
the wire with greater difficulty, or hard spots in the wire. This point of the position
of the machine at which such obstruction may occur, it will be understood, may
readily be a point on the cam when the same has almost entirely travelled the length
of its circumference.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. In a stop mechanism for cutting or turning machines, a reciprocable connecting
rod, a tool operated thereby, a part slidable by the connecting rod adapted to be
moved by the latter, a spring interposed between the rod and the tool, and a device
as a clutch or belt shifter adapted to be operated by the slidable part on the alteration
in length of the spring caused by abnormal conditions of working, substantially as
described.
2. In a stop mechanism for cutting or turning machines, a reciprocable connecting
rod, a lever capable of being rocked by said rod, a part which can be operated thereby,
and a spring interposed between said ro and lever, through which the power is
transmitted, said spring being continuously altered in length during normal working
of the parts but only sufficiently under abnormal working, to effect a stoppage of the
machine, substantially as described.
3. In a stop mechanism for cutting or turning machines, a reciprocable connecting
rod, a tool operated thereby, a part slidable in the rod adapted to be moved by the
latter, a spring interposed between the rod and tool, a device as a clutch or belt
shifter, a pivoted lever connected to same, and a T head to the lever presenting a
considerable surface for the slidable part to act on, upon alteration in length of the
spring caused by abnormal conditions of working, substantially as described.
4. In a stop mechanism for cutting or turning machines, the construction with a
connecting rod forming part of a tool operating device, and a lever forming part of a
device such as a clutch or belt shifter, of a housing for the end of the rod, a spring
compressible by said rod in said housing, a rod slidable in said connecting rod at
right angles thereto, and passing through the housing, a cam slot in said
connecting rod, and a pin projecting from said slidable rod into said slot, so that
a movement of the connecting rod in the housing caused by compression of the spring,
will move the slidable rod at right angles to the connecting rod and cause it to strike
the lever forining part of the clutch or the like, substantially as described.
5. The improved stop mechanism for cutting or turning machines operating under
abnormal conditions of working, substantially as described.
Dated the 15th day of November 1908
PHILIP M. JUSTICE,
55 and 56, Chancery Lane, London, Chartered Patent Agent,
For the Applicants.