IMPROVEMENTS IN MACHINES TO BE USED IN THE MANUFACTURE OF WOOD SCREWS
Year: 1884

page_text: I, WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake and Co, Patent
Agents, Southampton Buildings, in the County of Middlesex, do hereby declare
the nature of my invention for "IMPROVEMENTS IN MACHINES TO BE USED IN
THE MANUFACTURE OF WOOD SCREWS" 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 machines for forming scrow threads upon blanks by
rolling, and comprises a rotating cylindrical die and a stationary curved die,
employed for progressively forming helical threads upon scrow blanks, which aro
caused to roll around the concave face of the stationary die by the impingement
upon them of the periphery of the rotating die; improved means for gauging the
position of the pointed ends of the blanks in the act of feeding them to the dies;
and improvements in the general organization of the machine.
In the working of the improved machine, the thread is formed upon the body of
the blank, and upon its point, by a single progressive operation, and the first part
of the invention relates to the shape of the dies by which the formation of the
thread in a single progressive operation is effected. Thus the rotating dic has
formed upon its periphery a series of inclined parallel ribs which have the shapo
of V-threads for portions of their lengths, and are then transformed into truncated
threads, having their faces gradually and progressively increased in width from
the point where they begin to take the truncated shape to the point where the
truncated shape terminates and the V-shape begins.
In the accompanying drawings,
Figure 1 is a front elevation of a machine, constructed according to this invention,
for wallin O

page_text: Figure 5 is a top view, similar to Figure 4, except that it shows the delivery bar
in the act of pushing a blank against the rotating die.
Figure 6 represents a development upon a plane of the periphery of the rotating
dic.
Figure 7 is a transverse section of the rotating die, taken through the line xx
on Figure 6; also showing, in transverse section, a portion of the stationary die.
The machine has a substantial frame, A, upon the top of which are the boxes
for the driving shaft a, provided with the usual fast and loose pulleys a¹ and a².
The bevel pinion a³, upon the front end of the counter-shaft N1, meshes with
the bevel wheel at affixed to the upper end of the vertical shaft B, to the lower
end of which is affixed the rotating die C.
The stationary curved die D partially surrounds the rotating dic, and is supported
upon the horizontal member A₁ of the frame. The horizontal members A² and A³
of the frame afford the bearings B1 and B2 for the vertical shaft B.
Affixed to the shaft B are the two cams b and b', for rocking the levers b² and 63,
which impart end wise sliding movements respectively to the check bar b and the
delivery bar b, by the reciprocating movements of which the screw blanks are
successively delivered from the lower end of the conducting ways E into the space
between the rotating die C and the stationary die, D.
Heretofore the blanks, preparatory to their delivery to the dics, have been
supported by their heads, therefore. any. variation in the length of the blank
involved a corresponding variation in the length of the threaded part of the screw.
The present improvement in the method of feeding consists in causing each
blank, preparatory to its delivery to the dies, to be supported upon its point, that
is upon the end of the shank opposite the head. This is accomplished by means of
the adjustable gauge-plate e, upon or against which the points of the blanks rest
as they are checked off, one by one, from the lower end of the inclined ways E.
In order to prevent the blank, while resting upon the gauge plate e, from tipping
against the die, there is affixed to the frame the curved spring finger f which extends
across the path of the blank but yields laterally as the blank is pushed toward the
rotating die by the inward movement of the delivery bar 6. The spring serves to
hold the blank in an upright position against the end of the delivery bar b while
the bar is feeding the blank to the dies.
This mode of delivering the blank, which may be termed "measuring by the
point," is especially important for effecting the proper presentation of the blank to
the flaring part C of the rotating die, which flaring part is provided with the ribs
which form the gimlet point of the screw.
Preparatory to having the thread rolled upon it, the blank, G is usually pointed,
or rendered more or less nearly conical.
During the operation of rolling the thread, the blank has a slight tendency to
elongate. It will hence be seen that the vertically adjustable gauge-plate e affords
the means of accurately controlling the elevation at which the blank is fed to the
dies, so that the lower or pointed end of the blank will be properly presented to
the gimlet pointing die. In making the adjustment, the slight elongation to which
the blank is subjected during the rolling process is taken into account, and the
gauge plate is adjusted to so elevate the blank, that, when elongated, the metal
of its lower end will completely fill the spaces between the ribs of the gimlet
pointing die.
The ribs upon the gimlet pointing die C', with the exception that the periphery
of that part of the die is flaring, are the same as the ribs upon the cylindrical part
of the die which form the thread upon the body of the blank, that is, they have
for a portion of their length the shape of V-threads, and are then transformed
to the shape of truncated threads of gradually increasing width of face. The
continuous increase in the width of the faces of the truncated ribs is especially
essential when the gimlet pointing die is employed, because tho gripo of the dios
upon the sides of the thread is, in such case, continued without any diminution of
energy until the conclusion of the rolling operation.

page_text: In operation, the V-shaped portions of the ribs first impress a V-shaped helical
groove in the body of the blank, and then gradually widen the bottom of this
groove by crowding the metal of the blank laterally, and this. lateral crowding of
the metal continues until the blank has completed its journey through the dies.
The metal displaced laterally by the wedging action of the ribs, enters, and finally
fills the spaces between the ribs, and is thus made to take the form of a helical
thread around the body of the blank.
The length of the arc of the circle occupied by the ribs from the place where
they have the V-shape, to the place where their truncated shape terminates will
vary according to the radius of the die.
The drawings are intended to represent two sets of ribs, oach occupying one half
of the circumference of the die. In Figure 6 of the drawings, therefore, the
V-shaped portions H of one set of ribs are shown in juxtaposition with the terminal
truncated portions I of the other set of ribs.
The stationary die is provided with a series of inclined parallel ribs, which, for
a portion of their lengths are V shaped in cross section, and are then transformed
into truncated threads having faces progressively increasing in width, similarly to
the reversely inclined ribs on the rotating die, but the sides of the ribs which
constitute the side walls of the recesses in the stationary die are less inclined
relatively to each other than the side walls of the corresponding ribs upon the
rotating die, for the purpose of preventing the sides of the ribs of the stationary
die from having any bearing upon the sides of the thread formed upon the blank
by the rotating die.
This mode of construction is illustrated in Figure 7 which is a transverse section
taken through a portion of the rotating die and a portion of the stationary die,
showing the screw in elevation. This section is taken near the point at which the
screw is completely finished and discharged from the dies.
It will be seen that the threads g, g, g, &c, upon the body of the blank, fill the
recesses c, c, c, &c both in the cylindrical part of the rotating die, which forms the
thread upon the body of the blank, and in the flaring part C' of the rotating die
which forms the gimlet point.
It will also be seen that the threads, g, g, g, &, of the blank do not fill the
recesses d, d, d, &c, formed in the stationary die D, and that the faces d', d', d¹, &,
of the ribs of the stationary die alone bear upon the screw, their bearing being
upon the core of the screw, between the convolutions of the thread.
One of the results of this mode of organizing the dies is that in rolling certain
sized screws, no back rest or inclined stationary die may be needed for the gilet
point G¹; therefore in changing the machine for rolling such sized gimlet-pointed
screws of different lengths it will only be necessary to change the rotating die, the
stationary die being made of any desired width to accommodate it to the purpose of
performing its function of a back rest for supporting the longest screw for which
the machine is intended.
Another important consequence resulting from this mode of constructing the dies
is that during the operation of rolling the thread, the position of the blank is
controlled by the rotating die, and the blank will have no tendency to run up or
down in the course of its journey through the dies. This results from the fact
that the ribs of the stationary die are so shaped that their faces only bear upon the
blank; provided of course, that the blank is fed to the dies at the time when
the V-shaped portion of the rotating die is opposite the V-shaped portion of the
stationary die.
}
As the blank is rolled along the face of the stationary die by the action of the
rotating die, the helical groove between the convolutions of the thread formed upon
the blank gradually becomes flat-bottomed, and its flat bottom gradually widens.
This transformation in the shape of the helical groove is effected by the ribs of the
rotating die, so that, at any given point in the course of the journey of the blank
between the dies, the ribs of the rotating die completely fill the convolutions of thị

page_text: spiral groove upon one side of the screw blank, while the ribs of the stationary dio,
at the same point, do not fill the grooves upon the other side, but bear only upon
the coro of the screw. Thus the stationary die may, if desired, perform merely the
function of a back-rest.
It will be understood that, when required, the lower edge of the stationary curved
die D may also be made flaring correspondingly to the flaring part C₁ of the
rotating die, and be provided with ribs so that it will act as a back-rest for the
point of the screw which is being threaded.
The stationary curved die D is made adjustable toward, and from, the face of
the rotating die by means substantially similar to those described in the
specification of former Letters Patent dated June 11th AD 1883 N° 2904.
The supply of blanks is contained in the usual "hopper K provided with the
usual rocking lifter L. The blanks hanging by their heads upon the upper edges
of the parallel plates 1, 1 of the lifter, when the lifter is raised, slide down into the
conducting ways E. Motion to rock the lifter is transmitted by means of the
pitman L, pivotted at its lower end to the lifter crank arın L, and pivotted at its
upper end to the crank pin M inserted in the face of the gear wheel M¹ driven by
the pinion M affixed to the transverse counter-shaft M².
The shaft M is provided with the bevel wheel M³ which is rotated by the bevel
pinion N, affixed to the intermediate countershaft N', which is driven by means of
the gear-wheels N' and Ns from the driving shaft a of the machine..
One of the new features of the machine consists in the organization of the
shafting which permits the rotating die to be affixed to the. lower end of the
vertical shaft B, which carries it so that the minute cuttings from the blanks and
the lubricating fluid fall from the dies directly into the oil-pan, O. The machine
is provided with an oil-tank 0¹, from which oil is conducted and discharged upon
the dies by the usual pipe O².
Another feature of the machine is the drawing bolt P, for assisting in the
adjustment of the stationary curved die D toward and from the face of the rotating
die. The drawing bolt P engages the middle or bight of the curved die D, and
can therefore be employed to pull the curved die away from the face of the
rotating die.
By means of the usual horizontal adjusting screws Q, Q, the end portions of the
curved die are pressed toward the rotating die as may be required.
The drawing-bolt P may be operated to pull the central portion of the curved a
die D away from the rotating die, while the end portions of the curved die D bear
against the ends of the screws Q, Q. Means are thus afforded for changing the
curve of the die D, if such change is desired.
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 :-
First. In a machine for rolling threads on screw blanks, a cylindrical die having
formed upon its periphery a series of inclined parallel ribs, which, for portions of
their lengths, are V-shaped in cross section, and are then transformed into the
shape of truncated screw-threads having faces progressively increasing in width
from the point where they commence to take the truncated shape to the point
where the ribs having the truncated shape terminate and those having the V-shape
begin.
Second. In machines for rolling screw-threads upon scrow-blanks, a rotating
cylindrical die having formed upon its periphery a series of inclined parallel ribs,
which for portions of their lengths are V-shaped in cross section, and are then
transformed into the shape of truncated screw-threads having faces progrossively
increasing in width from the point where they commence to take the truncated
shape, to the point where the ribs having the truncated shape terminate and those
having the V-shape begin, in combination with a stationary curved back-rest
having formed upon its face a series of inclined parallel ribs, similar in form to

page_text: the series of reversely-inclined parallel ribs upon the face of the rotating die, but
of less area in cross section, and thereby adapted to bear only upon the core of a
screw blank rolled between dies as described.
Third. In machines for rolling screw-threads on screw-blanks, a rotating
cylindrical die, substantially such as described, in combination with a stationary
curved die having formed upon its face a series of inclined parallel ribs which are
similar to the series of reversely-inclined parallel ribs formed upon the rotating die,
excepting that the sides of the ribs which constitute the walls of tho recesses
between the ribs are less inclined relatively to each other than the sides of the
corresponding portions of the ribs of the rotating die.
Fourth. In mechanism for feeding screw-blanks to dies for rolling the threads
upon them, the adjustable gauge-plate e for gauging the position of the pointed
end of the blank relatively to the dies preparatory to the feeding operation.
Fifth. The gauge-plato e for fixing the position of the pointed end of the blank,
in combination with the delivery-bar 6, and the spring finger f for holding the
blank against the end of the delivery bar, substantially as, and for the purpose, set
forth.
Sixth. In a machine for rolling the threads upon screw-blanks, substantially as
described, the rotating die C affixed to a vertical shaft B which is driven by suitable
gearing acting upon a part of the said vertical shaft which is above the part to
which the die C is affixed, whereby the drippings from the die fall directly into the
oil-pan beneath the die.
:
Seventh. The combination, substantially as described, of the rotating die C, the
stationary die D, and the drawing-bolt P, as, and for the purpose, set forth.
Eighth. The combination, substantially as described, of the rotating die C, the
stationary die D, the drawing-bolt P, and the adjusting screws Q, Q, as, and for
the purpose, set forth.
Dated this 7th day of October 1884
HASELTINE, LAKE & Co.,
For the Applicant.