Improvements in Milling Machines.
Year: 1893

page_text: Date of Application 25th July 1893-Accented 11th Nov. 1893
COMPLETE SPECIFICATION.
[Communicated from abroad by THE RUSSELL AND ERWIN MANUFACTURING
COMPANY, of New Britain, Connecticut, United States of America.]
Improvements in Milling Machines.
I, LEONARD DOIG, of 47 Upper Thames Street, in the City of London,
Manager of The Russell and Erwin Manufacturing Company, 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 :-
My invention relates to improvements in milling machines chiefly intended for
producing dies for rolling screw threads.
In the accompanying drawings-
Figure 1 is a plan view of my special die-milling apparatus, and so much of a
milling machine as is necessary to show its connection therewith.
Figure 2 is a front elevation of portions of the same, some of the parts being
shown in sectional profile.
Figure 24 is a like view showing the same parts in a modified form.
Figure 3 is a side elevation of a portion of the milling-machine head, the cutter
spindle being shown in transverse section.
Figure 4 is a side elevation of the cutter on an enlarged scale.
Figure 5 is a view on the same scale as Figure 4 showing the device for giving
lateral vibration to the cutter.
Figure 6 is a diagram illustrating the action of the cutter on the die-block.
Figure 7 is a face view of one form of die produced by my apparatus.
Figure 8 is a sectional view of the same on the line a Figure 7.
Figure 9 is a sectional view of the same on the line y y Figure 7.
Figure 10 is a sectional view of the same on the line z
Figure 7.
Figure 11 is a face view of a die-block with a few grooves such as may be cut
with my apparatus, although their taper is exaggerated as compared with a die for
practical use.
Figure 12 is a longitudinal section of the block Figure 11 through the middle
of one of its grooves.
Figure 13 is a similar face view illustrating in an exaggerated form the die-
grooves and intervening ribs such as I prefer to use.
Figure 14 is a longitudinal section of a portion of the same through the middle
of one of the grooves.
Figure 15 is a transverse section of the same on the line v v Figure 13.
Figure 16 is a side view of an oval cutter for use in producing a die.
Figures 17, 18 and 19 are end views of the die-blocks with grooves such as may
be cut with my apparatus.
Figure 20 is a plan view of a modified form of wedge.
Figure 21 is an enlarged diagram illustrating the form of die-groove at various
points along its length.
A designates the frame of the head of an ordinary milling-machine in which the
front boxes or bearings 20 are permitted to rise and fall as best shown in Figure 3,
the same being pressed downward by the springs 21. B designates the cutter
spindle fitted to rotate in said bead and having a hub 22 the side of which farthest
from the cutter 23, being preferably bevelled off as shown. The other side of
this hub 22 has a curved recess extending diametrically across its axis, while
outside of said recess its face is bevelled off in each direction as best shown in
Figures 1 and 5. That side of the cutter which faces the hub 22 is provided
with a diametrical rib 24 which is curved transversely to its length and which rests
in the curved recess of said hub. The curve of this rib and recess is on a radius

page_text: that equals the distance from the highest point of said rib to a plane passing
through the apices of all the cutter teeth. The central hole in the cutter 23 is
made slightly oval as shown in Figure 4, the longer diameter of said hole extending
at a right angle to the rib 24. The shorter diameter is of a size substantially equal
to the diameter of that part of the spindle to which it is fitted. If desired I also
provide the cutter with a dog pin 30, Figures 4 and 5, that engages a groove in the
confronting face of the hub 22 to assist in driving the cutter with the spindle.
The tail block of the spindle B is grooved longitudinally as at 26 Figure 5, and
on this grooved portion is a sliding sleeve 28 having a spline or pin 27, which
engages said groove, whereby said sleeve necessarily rotates with the spindle and
at the same time is permitted to slide longitudinally thereon. Secured to this
sleeve is a rigid arm 29 the end of which when in use bears upon one side of the
cutter 23 toward its outer edge, ou a diametrical line substantially at right
angles to the middle longitudinal line or axis of the rib 24, and at a point
diametrically opposite said rigid arm 29 a spring pressed arm 31, secured to said
sleeve, bears upon the side of the cutter. Said sleeve and arm constitute a yielding
mechanism for keeping the cutter in position.
This sleeve is held in position on the spindle by contact with a wedge or
pattern 32 in the tail block spindle 33, said spindle being held and adjusted within
the tail block C by means of the nuts 34 and 35 on a threaded part of said tail
block spindle. The wedge 32 is fitted to slide longitudinally from front to rear
across the end of the tail block spindle, and at its rear end is an arm 36 which
engages a groove 37 in a part that is rigid with the carriage D. Upon the
carriage D a vice G is pivoted as at 38 and within the jaws of this vice I place
the die block 39 for being milled. As in an ordinary milling-machine, the carriage D
is adapted for being fed in a right line from front to rear or vice versa, and also to
be moved longitudinally with the spindle and set at any desired point. The vice is
also provided with a lifting rib 40 the upper edge of which is preferably somewhat
rounded and projects upward near the periphery of the cutter as shown in
Figure 2. This lifting rib is held by screw 41 within a slot provided to receive it
so that by turning the adjusting screws 42 its distance from the cutter or its angle
of inclination to the vice and carriage may be varied as desired. Said hub 22 and
lifting rib 40 may be of the form shown in Figure 2 without changing the result
in this case the hub has a rounded edge and the rib an inclined surface.
An arm
or projecting bar 47 that is rigid with the vice G is arranged between the index
screw 43 having a division plate or index 44 and a holding spring catch 45 on the
one side, and a set screw 46 on the other side, by means of which the inclination of
the vice may be changed by moving said index screw a given distance. A stout,
spring to hold the opposite side of the arm 47 against the index screw 43 should
be an equivalent of the set screw 46. Instead of a cutter that is round in side
view I sometimes employ one that is more or less oval as shown in Figure 16, and
this will be fitted to the spindle B in a manner before described for mounting
the cutter 23 thereon. I generally form the diametrical rib which I will term the
wobbling axis of the cutter, on the line of its longer diameter as indicated by the
line uu, but for some uses the wobbling axis should be made on the line of its
shorter diameter as indicated by the line ww. The difference between the longer
and shorter diameter of the cutter may be varied according to the work to be
performed. I may also change the shape of the wedge 32 which is in the nature
of a guide or pattern, from the true taper shown in Figure 1 by giving it parallel
sides for a portion of its length as shown at 48 Figure 20, or any other form.
The various features of dies produced by this apparatus will be described in
connection with the operation of the machine. As in ordinary dies for rolling
screw threads, the grooves extend along the length of the die-block somewhat
obliquely, the angle of inclination being determined by the position that the die
block is set on the carriage with reference to its movement across the axis of the
spindle. For convenience I will describe each groove and the operation of cutting
it as if all the grooves extend alike from end to end of the die-block, although

page_text: some of them in fact are shorter by extending across the corners of the block.
The carriage is set in proper position to bring the path of the die-block and
carriage from front to rear under the cutter in the line of the grooves to be cut.
If the sleeve 28 is set so that the arms 29 and 31 hold the cutter with the plane
through the points of the teeth at right angles to the axis of the spindle, the
cutter will run perfectly true and make a groove exactly the shape of the cutter
teeth, the same in this instance being that of a perfect V, but if the sleeve is set
nearer to or further from the cutter the combined action of the rigid arm and
spring arm will swing the cutter on the rib 24, the longitudinal axis of which is
the wobbling axis of the cutter, and consequently said cutter in revolving vibrates
from side to side or in other words will wobble. By adjusting said tail block
spindle by means of the nuts 34 and 35, the wedge 32 may be set so that the
cutter will run perfectly true when any desired point of the wedge is in contact
with said sleeve, and thus the cutter may be made to run true when the parallel
When
portion 48 of the modified wedge, Figure 20, is in contact with said sleeve.
I use a wedge that has a uniform taper throughout its bearing face, I adjust the
tail block spindle so that the cutter runs true, (which for convenience I will call
the focussing point,) when the sleeve is a short distance from the rear end of this
bearing face. I start the cutter in at the rear end of the die-block at which point
the cutter wobbles and cuts a somewhat truncated V, the same growing gradually
less truncated until the point of focus is reached and a perfect V shaped slot is
made. From this point on, as the wedge 32 is drawn back with the carriage, the
sleeve 28 is gradually pressed toward the cutter so that the rigid arm pushes
that side of the cutter and inclines it more and more on its wobbling axis.
while the spring arm 31 yields to accommodate said movement and at the
same time it holds the cutter firmly in its seat. Thus the cutter wobbles more
and more while its bevelled sides cut the sides of the grooves with a gradually
warped or changing angle of inclination, making the groove wider and wider,
while the apex of the cutter sweeps out the bottom of the truncated V-shaped
groove on the arc of a circle as illustrated in Figure 6 in which one position of
the cutter on the wider part of the groove is shown in full lines while its position
as vibrated to the opposite side of the groove is represented by the broken
outlines of the complete cutter, and the position of the cutter at the point of
focus where the perfect V-shaped groove is made is indicated by the broken lines
of a portion of the cutter's edge midway between the other two positions. This
same view also shows that if the vibration of the cutter were great enough so
that the apex of the cutter would run out on the surface of the die-block 49 the
entire groove at that point would be on the arc of a circle.
The die-block Figure 7, was cut with a concentric cutter the focussing point
thereon being indicated by the line a while the vibration of the cutter was not
great enough to make the apex run out at the face of the block. This block was
also set in the vice with the upper end of Figure 7, a little higher than its opposite
end, hence the grooves are deepest at said upper end. This die-block is also
provided with a raised portion 50 for threading the gimlet point of the screw, a well
known feature in this class of dies. After each cut the die-block was brought
forward again and then moved laterally the desired distance for the next groove
and so on repeatedly. Furthermore after several of the shorter grooves that extend
across the lower right hand corner of the die-block had been milled, and the point
threading portion approached the cutter, the lifting rib 40 came in contact with the
tapering end of the hub 22 of the spindle, and gradually raised the cutter, said rib
at first striking the lower part of said taper and then by reason of the inclination of
said lifting rib at its point of contact gradually worked up said taper and lifted the
cutter over the point threading projection at just the proper height to let the cutter
groove said projection in continuation of the grooves in the flat part of the die.
The shape of the die Figure 7 as thus made is shown by cross section in Figures 8,
9 and 10, at the respective lines, y and of said Figure 7. Of course the die
Figure 7 is one of a pair.
=

page_text: In Figures 11 and 12 I have shown the same form of groove made in the same
way but on a more abrupt taper. Furthermore after one groove has been milled
and the carriage drawn to the front and moved laterally toward the right a given
distance equal to the distance from the centre of the groove to the next at the
focussing point, the index screw 44 was let back or unscrewed a given distance of
the index and followed up by the set screw 46, thereby bringing the rear end of
the die-block (the lower end in Figure 11, the same being the entering end of the
die in use,) a little nearer to the path of the next groove to be cut and so on before
starting each groove, whereby the longitudinal centres of the die grooves diverge
as they approach the finishing end of the die. In practice this divergence is too
small to be shown by an ordinary drawing and therefore Figure 11 is exaggerated
in this particular. The divergence should be only just enough to accommodate the
rise of the stock or the increase in diameter as the thread is rolled whereby the
screw may be made to travel squarely over the face of the dies and parallel to
the point-threading portion. In Figures 11 and 12 I have also shown the grooves
so wide at the entering end of the die that the plain flat surface of the ribs 51
between them vanish at 52, and from that point to the lower end of the block the
ribs are V-shaped with their summit or apex sloping longitudinally toward said
lower end, the same being formed by merely making the grooves proportionally
wider so that their sides run together. This permits the dies to take hold of the
stock by sharp ribs with shallow penetration and then work in deeper until the
point 52 is reached and from that point onward the penetration may be continuous
or changing according to the position in which the faces of the dies are set relatively
to each other.
The
Figures 13, 14 and 15 show a die-block as made with an oval cutter.
focussing point is indicated by the line s s. The grooves widen each way from this
point gradually changing from the perfect V to the truncated V with curved
bottom until the point is reached. Here the periphery of the cutter ran out at
the face of the die-block and from that point on to the lower end of the die the
grooves are formed wholly by a curve as shown by the section Figure 15. These
curves are on a smaller radius than are the curved bottoms of the grooves as made
by the round cutter 23. The tops of the ribs 53 between these also slope toward
the lower or entering end of the die as in Figures 11 and 12 but unlike the grooves
in said Figures 11 and 12 they do not have any part which in transverse section
shows a right line or bevelled sides, because the right lines at the sides of the
grooves are made by the bevelled sides of the cutter teeth and the curved lines
are made by the apex of the teeth. From this it will be seen that there is
a gradual change of the right lined and warped inclined sides and curved bottom
of the grooves from the line v v to the upper end of the die. By the use of the
wedge with parallel sides 48 at one end and with the tail block spindle set to
make the cutter focus when the sleeve is on said parallel end, the grooves in the
finishing end of the die may be perfect V-shaped grooves with parallel sides
throughout that part of the die-block which is cut when the sleeve is on the straight
part of the wedge, and then they may taper as before described as the sleeve is
acted upon by the tapering portions of the wedge.
By giving more or less of the oval form to the cutter, grooves may be cut of either
of the forms shown in Figures 17 and 19, and by changing the wobbling axis of the
oval cutter from u u to w w Figure 16, grooves of the form shown in Figure 18
may be cut at a single pass of the cutter.
When a cutter that is V-shaped in edge view and oval in side view is used whose
eccentricity exceeds the depth of the grooves in the die-block, the tapering portion
of the groove will be in the form of a modified V or a V with curved sides as
shown in Figures 19 and 21 and a true V-shape at the focussing point as indicated
by the middle portion of the diagram Fig. 21. The curved lines on each side of
this middle V represent sections through the tapering portions of the grooves at
several successive points along the length of the groove, from which it will be
seen that the sides of the groove of this form as well as the forms shown in

page_text: Figures 6, 7, 8, 9 and 10 have a warped surface extending along their length with
a constantly changing angle of inclination. Of course grooves of other forms
could be cut by giving the cutter a different form in edge view.
By means of my apparatus I am enabled to make a die with a series of rounded
grooves with narrow ridges between them at the entering end of the die, followed
by grooves with the bottom filled up in the form of a truncated V and then a
finishing portion where there is no increase of pressure on the stock, substantially
like the die described in the Specification of British Letters Patent No. 5345
dated April 8th 1890, my said improved die however giving a curved form to the
bottom of the truncated V-shaped groove. I can make the finishing end of the
die either with parallel-sided grooves as in said Patent by use of the wedge
Figure 20, or by use of the wedge 32 I make said finishing end taper in the reverse
direction, the taper being so slight as to give a good finish to the thread although
the pressure on the stock is slightly relieved after passing the focussing point of the
die. The curved grooves and narrow ridges at the entering end of the die have
the same functions and objects as in said Patent. The bevelled sides of the grooves
in the die herein described are believed to have a better action by the gradual
change of their angle of inclination from end to end, that angle being less at the
wider part of the groove.
By making the grooves diverge slightly toward the finishing end, I provide for
the gradual enlargement of the circumference at the top of the thread as it is built
up above the core in the progress of the screw through the dies, so that when the
thread in rolling leaves one groove (as for instance at the edge of the die) to
engage the next one it will strike the middle of said groove, instead of one side,
and squarely enter the same and consequently pass squarely through the dies in a
direction parallel to the point-threading portion instead of travelling in the arc of
a circle.
My apparatus is capable of milling a great variety of grooves each of which can
be made at a single pass of the cutter, the variations being accomplished by varying
the angle of the wedge or giving different forms to its face; by changing the
position of the wedge relatively to the sleeve on the tail block end of the spindle
by changing the contour of the cutter either in side view or edge view or both; by
raising the cutter up and down with the lifting rib and hub, the form and position
of which may be changed by swinging the vice and die-block between the stated
points of feeding it along to cut different grooves, and by tipping the die-block to
raise one or the other end more or less.
It is obvious that a wobbling cutter of non-circular contour, or a circular cutter
with a variable wobble, may be used for giving an uneven surface to various
materials for various purposes, and therefore I do not confine the use of this device
exclusively to the making of dies as herein described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is :-
1. In an apparatus for forming uneven surfaces, the combination of a rotating
spindle, a cutter mounted thereon and provided with an axis transverse to that of
said spindle, and means for controlling the position of said cutter on said transverse
axis, substantially as described, and for the purpose specified.
2. The combination of a spindle having a shoulder with a transverse curved
recess, a cutter mounted on said spindle and having a transverse axial rib fitted in
said curved recess, the axis of which rib is in the plane of the apices of the cutter
teeth, and devices for holding said cutter in place, substantially as described, and
for the purpose specified.
3. The combination, with a wobbling cutter mounted upon a rotating spindle, of
a yielding holding mechanism, a carriage and a moving wedge or pattern bearing
upon said yielding holding mechanism to govern the position of the cutter on its
wobbling axis, substantially as described and for the purpose specified.

page_text: 4. The combination of a wobbling cutter mounted upon a rotating spindle, with
the sleeve 28, rigid arm 29, yielding arm 31, and a moving wedge or pattern for
acting upon said sleeve, substantially as described, and for the purpose specified.
5. The combination of a spindle mounted to rise and fall, a hub and cutter on a
spindle, a carriage for moving the work by said cutter and the lifting rib on said
carriage for acting on said hub to raise the cutter, substantially as described, and
for the purpose specified.
6. The combination of a mounted milling-machine cutter for milling screw-
threading dies, the carriage of said machine, the vice pivoted to said carriage as
at 38, and an indexing device for moving said vice a given distance on said pivot
after cutting each groove to change the angle of inclination, substantially as
described, and for the purpose specified.
7. In a machine for making ribbed dies for rolling screw threads, a pivoted vice
for holding said dies, an indexing device for swinging said vice upon its pivot, and
means for giving said vice a graduated lateral movement, substantially as described,
and for the purpose specified.
8. In a machine for forming uneven surfaces, a cutter of oval, or excentric, or
cam-shaped contour in combination with means for giving the same a wobbling
motion, substantially as described and for the purpose specified.
9. Milling-apparatus constructed substantially as described with reference to the
drawings, for the purpose specified.
T11002
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the.Applicant.

page_text: Date of Application, 25th July, 1893-Accepted, 18th Nov.,
1893
COMPLETE SPECIFICATION.
[Communicated from abroad by THE RUSSELL & ERWIN MANUFACTURING
COMPANY, of New Britain, Connecticut, United States of America.]
Improvements in Dies for Rolling Screw-threads and the like.
I, LEONARD DOIG, of 47 Upper Thames Street, in the City of London, Manager
of The Russell & Erwin Manufacturing Company, 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 dies for rolling screw-threads and the like, and has for
its object to provide a superior die having all or part of the several features
hereinafter described.
In the accompanying drawings,
Figure is a face view of one form of die constructed according to this
invention.
Figure 2 is a sectional view of the same on the line x, x, Figure 1.
Figure 3 is a sectional view of the same on the line y, y, Figure 1.
Figure 4 is a sectional view of the same on the line, z, Figure 1.
Figure 5 is a face view of a die-block with a few grooves, the taper of which is
shown exaggerated for convenience of illustration.
Figure 6 is a longitudinal section of the block shown in Figure 5 through the
middle of one of its grooves.
Figure 7 is a similar face view illustrating in an exaggerated form the die-
grooves and intervening ribs such as I prefer to use.
Figure 8 is a longitudinal section of a portion of the same through the middle of
one of the grooves.
Figure 9 is a transverse section of the same on the line v, v Figure 7.
Figures 10, 11 and 12 are end views of other die-blocks made in accordance with
this invention.
Figure 13 is an enlarged diagram illustrating the form of die-groove at various
points along its length.
The dies forming the subject of this invention can be produced conveniently in
the manner and by the apparatus described in the Specification of Letters Patent
No. 14358 bearing the same date as the present application.
As in ordinary dies for rolling screw-threads, the grooves extend along the
length of the die-block somewhat obliquely. At the entering end of the die-
block each groove has the form of a truncated V, the same growing gradually
less truncated as the distance from said end increases until a perfect V shape is
reached, from which point onward the sides of the groove have a gradually warped
or changing angle of inclination, making the groove wider and wider. The bottom
of the truncated V-shaped groove is curved to the arc of a circle.
obvious of course that some of the grooves will run out at the side of the die-
block before developing all the characteristics above described.
It will be
The die-block shown in Figure 1 has perfect V-shaped grooves at the point
marked, x, and the grooves are deepest at that end of the block. The said
blck is also provided with a raised portion 50 (grooved in continuation of the
grooves in the flat part of the die) for threading the gimlet point of the screw, a
well-known feature in this class of dies. The shape of the die as thus made is
clearly shown by the Figures 2, 3 and 4 at the respective lines x, y, z of the said
Figure 1. Of course the die, Figure 7, is one of a pair.
In Figures 5 and 6 I have shown the same form of groove made in the same
way but on a more abrupt taper, and having the longitudinal centres of the die-
groove diverging as they approach the finishing end of the die. In practice this

page_text: divergence is too small to be shown by an ordinary drawing and therefore
Figure 5 is exaggerated in this particular. The divergence should be only just
enough to accommodate the rise of the stock, or the increase in diameter, as the
thread is rolled, whereby the screw may be made to travel squarely over the face
of the dies and parallel to the point-threading portion. In the said Figures 5
and 6 I have also shown the grooves so wide at the entering end of the die that
the plain flat surface of the ribs 51 between them vanish at 52, and from that
point to the entering end of the block the ribs are V-shaped with their summit or
apex sloping longitudinally toward said entering end, the same being formed by
merely making the grooves proportionally wider so that their sides run together.
This permits the dies to take hold of the stock by sharp ribs with shallow
penetration, and then work in deeper until the point 52 is reached, and from that
point onward the penetration may be continuous or changing according to the
position in which the faces of the dies are set relatively to each other.
Figures 7, 8 and 9 show a die-block as made with an oval cutter.
The point
where the grooves become perfect V's is indicated by the lines, s.
The grooves
widen each way from this point, gradually changing from the perfect ✓ to the
truncated with curved bottom until the point, is reached from which point
onward the grooves are formed wholly by a curve of small radius as shown by the
section Figure 9. The tops of the ribs 53 slope toward the entering end of the
die as in Figures 5 and 6, but, unlike the grooves in said figures, they do not have
any part which in transverse section shows a right line or bevelled sides. It will be
seen therefore that there is a gradual change of the right lined and warped inclined
sides and curved bottom of the grooves from the line v, to the finishing end of
the die. The grooves in the finishing end of the die may be perfect V-shaped
grooves with parallel sides for a portion of their length, and then they may taper
as before described for the remainder of their length.
By giving more or less oval form to the cutter, grooves may be cut of either of
the forms shown in Figures 10 and 12, and in some cases dies may be produced
having grooves of the form shown in Figure 11.
In some cases I provide a die the tapering portions of whose grooves are in the
form of a modified V, or a V with curved sides as shown in Figures 12 and 13,
and a true V-shape at the middle portion as seen in Figure 13. The curved lines
on each side of this V in the said figure represent sections through the tapering
portions of the grooves at several successive points along the length of the groove,
from which it will be seen that the sides of the groove of this form, as well as the
forms shown in Figures 1 to 4, have a warped surface extending along their length
with a constantly changing angle of inclination. Of course I may provide grooves
of other shape than those shown.
By my invention I provide dies having a series of rounded grooves with narrow
ridges between them at the entering end of the die followed by grooves, with the
bottom filled up, in the form of a truncated V, and then a finishing portion where
there is no increase of pressure on the stock, substantially like the die described in
the Specification of British Letters Patent No. 5345 dated April 8th 1890, the
bottom of the grooves in my improved dies however being curved. I sometimes
make the finishing end of the die either with parallel-sided grooves as in said
prior Specification or I sometimes make the said finishing end taper in the reverse
direction, the taper being so slight as to give a good finish to the thread although
the pressure on the stock is slightly relieved after passing the point of the die
where the grooves are narrowest. The curved grooves and narrow ridges at the
entering end of the die have the same functions and objects as in said Specification
No. 5345 A.D. 1890. The bevelled sides of the grooves in the die herein described
are believed to ensure an improved action by the gradual change of their angle of
inclination from end to end, that angle being less at the wider part of the groove.
By making the grooves diverge slightly toward the finishing end, I provide for
the gradual enlargement of the circumference at the top of the thread as it is
built up above the core in the progress of the screw through the dies, so that

page_text: when the thread in rolling, leaves one groove (as for instance at the edge of the
die) to engage the next one it will strike the middle of said groove, instead of
one side, and squarely enter the same and consequently pass squarely through the
dies in a direction parallel to the point-threading portion instead of travelling in
the arc of a circle. Thus by giving the die grooves just the proper amount of
divergence to act as above described I accomplish in another way the same
object as is accomplished for example by the die described in the Specification of the
United States Patent of Jan. 13, 1891, No. 444,554, in which the point-threading
portion was on the arc of a circle and consequently parallel to the path of the
screw through the dies. I am aware that it has been previously proposed to
provide dies for rolling screw threads in which the grooves diverge toward the
finishing end to such an extent as to take up the excess of metal by an elongation
of the screw, so as to prevent an enlargement or building up of the thread beyond
the normal diameter of the stock, and I hereby disclaim the same. In my die the
divergence does not prevent the natural increase of diameter and is only just
sufficient to make the screw travel squarely through the dies.
It will of course be evident that my improved die may be made with a part
only of the features herein described; for instance the block may be so short that
the point where the grooves would become perfect V's will be just beyond the end
of the block, and that no portion of the curved part of the groove will meet the
face of the block, so that the rounded grooves and sloping ridges would be omitted
from the entering end of the die, while the middle portion would be the same as
herein described. It is also evident that the point-threading portion may be
omitted when desired.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is :-
1. A die for rolling screws having its face provided with alternate tapering
ridges and grooves, the latter varying in transverse section from a V-shape at one
point to the form of a truncated V with a curved bottom at another point, sub-
stantially as described, and for the purpose specified.
2. A die for rolling screws having its face provided with alternate tapering
ridges and grooves, the sides of the latter having a warped surface extending
along their length with a constantly changing angle of inclination, substantially as
described, and for the purpose specified.
3. A. die for rolling screw-threads having on its face alternate tapering ridges
and grooves, the sides of the latter running together at the entering end of the
die while the ridges between them at the points thus run together are brought to
an edge and slope toward said entering end, substantially as described, and for the
purpose specified.
4. A die for rolling screw-threads having on its face alternate tapering ridges
and grooves, and a finishing portion in which the grooves taper in the reverse
direction from that of the rest of the die, substantially as described, and for the
purpose specified.
5. A die for rolling screw-threads having on its face alternate tapering ridges
and grooves, the longitudinal centres of the grooves slightly diverging toward the
finishing end sufficiently to make the threads squarely enter the successive grooves
as the blank advances, substantially as described, and for the purpose specified.
6. A die for rolling screw-threads, constructed substantially as described with
reference to the accompanying drawings.
3 1
1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.