Improvements in Blank Supporting Device for Screw Threading Machines.
Year: 1888

page_text: Improvements in Blank Supporting Device for Screw Threading
Machines.
I CHARLES DAKE ROGERS, superintendent, of 21, Stevens Street, in the City of
Providence, in the County of Providence, and State of Rhode Island, one of the
United States of America, do hereby declare the nature of my invention for
IMPROVEMENTS IN BLANK SUPPORTING DEVICE FOR SCREW THREADING MACHINES
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
In the production of scrows, but more especially in the manufacture of wood-screws
in which the threads are impressed into the surface of the blank by means of the ribs
of suitably mounted and operated dies, it is the practice, so far as I am aware, to
support the blank during the rolling operation by means of a guide upon which the
head of the blank bears, or in some cases the point of the blank rests upon a plane
surface.
An objection to such former methods of supporting the blanks is that owing to the
lack of uniformity in the pointed portions of the blanks they are improperly introduced
to the threading-dies.
In the operation of pointing the blanks, or reducing the end portion to a cone-
shape, the metal is compressed somewhat by the action of the cutting-off and shaping
dies, and as it is practically impossible to accurately gauge the amount of metal
required to form the point, it follows that the points become more or less elongated.
It is evident now that if the point of the blank rests upon a bottom support or
table the base of the cone, which joins the cylindrical part of the blank, will not
in all cases coincide with the angle formed in the working face of the threading
dies. If the blank enters too high the thread produced upon the point will be too
thick and partially formed and consequently imperfect; if it enters too low there will
be a surplus of metal, and as there is no place for it to escape the blank becomes
clogged between the dies, thereby producing an immense strain upon them, and
occasionally fracturing them; the blanks obviously being imperfect.
From the foregoing it is apparent that to produce screws having perfect threads
upon the point portion it is essential that the base of the cone and the angle formed
in the working face of the dies must always coincide.
In order to attain this result I provide each threading die at its front end with a
thin strip of metal having the adjacent upper edges beveled or otherwise adapted to
receive the point of the blank between them and also arranged to sustain the blank
in position until the dies begin to act fairly upon it. By means of this arrange-
ment the blank is supported near the base of the cone-shaped point, the size or
diameter thereof at the point of contact being practically alike in all the blanks

page_text: when made from the same size or gauge of wire. It is evident now by holding the
blank in position laterally, that the supports will properly present the blanks to the dies.
In the drawings annexed, Figure 1 represents a plan view of a screw-threading
machine of the character indicated above; a portion of the feeding mechanism being
removed, and showing a blank supported in position preparatory to being acted
upon by the threading-dies. Fig. 2 is an enlarged side view in partial section,
taken through the center of the machine, showing a portion of a feeding device
having a blank therein supported by metallic strips which engage the upper portion
of the blank's point, and corresponding to the position shown in Fig. 1. Fig. 3
is an enlarged transverse sectional view taken through the line of Fig. 1,
showing the relation of the blank to the dies, supporting device, etc. Fig. 4 is a
similar sectional view, still further enlarged, showing only the two supporting
bars and the blank resting thereon; all the foregoing Figures being referable to
the position of the blank prior to its engagement with the threading dies.
Fig. 5 is a view of the lowor portion of a wood-screw blank having a normally
proportioned cone-shaped point, and Fig. 6 is a view of the end of a blank showing
the tendency of the point to elongate in case a slight excess of metal be present
during the cutting-off and pointing operation.
A more detailed description of my present invention is as follows :-
Referring to Fig. 1 in which is represented a machine for swaging or rolling
screw-threads upon blanks, a a indicate two cross-heads mounted in ways formed in
the main frame; these cross-heads are oppositely arranged and are adapted to travel
back and forth past each other by means of the gearing and connections, as clearly
shown; I make no claim herewith to this or any specific operating mechanism;
neither do I claim herewith the hopper c and feeding mechanism which conducts the
blanks m therefrom to the supporting device.
To each cross-head is secured a threading-die d, the two dies coacting to roll a screw-
thread upon and into the shank and point of the blank, as common.
To the forward end of each die, or to a holder e in which the dies are mounted, is
secured a thin piece or bar of metals, the same extending in front of and past each
other when the dies are in the extreme position, shown in Fig. 1, and preparatory to
acting upon the blanks. These bars, s, are susceptible of vertical adjustment by means
of screws passing through the slotted openings s¹. I prefer to bevel-off the upper
inner edges of the bars, as indicated by u, to correspond somewhat with the handle of
the blank's point p. By means of this arrangement the vertical distance from the
upper edgo of the bars to the base line, v, of the point will always be the same for
blanks of the same gauge of wire. It is obvious, however, that this distance may be
varied by a readjustment of the bars in a lateral direction, thereby affecting the width
of the space lying between them.
In Fig. 2 is shown a device for automatically conducting the blanks to the supporting-
bars s, the jaws ff being adapted to be intermittingly opened and closed at the proper
time by actuated cam-plates ii (shown sectionally); the lower portion of the jaws
is reduced in thickness and extends downwardly into the space formed by the
separation of the dies d; the meeting faces of the lower portion is slightly concave
to receive and hold the blanks in position laterally. A checking-plate 9 mounted
in the upper part of the feeding device is made to travel back and forth through
the medium of a cam-plate i, thereby uncovering the runway or track and permitting
a blank to enter the feed-box after which the plate forces it therefrom into the
enlarged space k from which it falls into the jaws fand is arrested and supported
by the bars s.
From the foregoing it is evident that blanks having points p of unequal lengths (as
shown in Figs. 5 and 6) will, when supported by the bars s, be uniformly presented
to the threading-dies; the diameter at the point (indicating say the line of support)
being the same.
•
If, however, the blanks be supported at the lower ends, as upon a surface w,
Figs. 5 and 6, it is apparent that the blank shown in Fig. 6 would carry the point
far too high when presented to the dies d, as compared with the pointed portion p

page_text: shown in Fig. 5. In these cases the length of the blanks are supposed to be the
same from the base y of the cone of the point to the head h¹.
By reason of my improved method of supporting blanks the tip or extreme end
of the point is preserved, which otherwise becomes more or less blunted before the
blank reaches the threading-dies.
It is obvious that the form and arrangement of the supporting bars & may be
changed or modified somewhat without departing from the spirit of the invention. I
prefer to employ blanks having a cone-shaped point; the heads may be slotted or
not as desired.
In the drawings I have represented both dies as traveling, but the blank-supporting
device is equally operative and practical in a machine having one die stationary and
the other driven, in which case a traveling carrier would be employed.
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. In a screw-threading machine the combination of holding-jaws for guiding the
blanks laterally and presenting them to the threading mechanism, a series of thread-
forming dies and combined blank-supporting and guiding plates mounted in advance
of said dies, all arranged and operating substantially as hereinbefore described.
2. In a screw-threading machine, the combination with the threading dies, of bars
or ribs mounted in advance of the dies and traveling in unison therewith, said bars or
ribs being separated and adapted to receive the point portion of the blanks, sub-
stantially as described and for the purpose set forth.
3. In a screw-threading machine, the combination with actuated blank-holding jaws
constructed to support the blank laterally, of oppositely mounted and actuated dies
or plates and bars, as s, mounted in advance of and moving in unison with the dies
and having the upper edges of the bars separated and arranged to receive the sides of
the point of the blank so as to support the blank and properly introduce it to the
dies, substantially as set forth.
4. In a screw-threading machine, the combination with threading-dies and
holding-jaws of two parallel adjustably mounted and actuated bars, ass, beveled at
their upper adjacent edges to receive the cone-shaped point of a screw-blank, thereby
assisting to support the blank in position to properly engage the threading-dies, sub-
stantially as hereinbefore described.
5. The combination with two oppositely mounted threading-dies and holding-jaws
of duplicate supporting-bars arranged side by side, but reversed in their movement,
and connected each with the forward end of a threading-die, so as to support a blank
at its point and properly present it to the said dies, substantially as set forth.
6. The improvement hereinbefore described for guiding and supporting the points
of screw-blanks by means of which they are accurately and uniformly brought into
engagement with the thread-forming dios, the same consisting of supporting bars
mounted in advance of and arranged to travel in unison with the said thread-forming
dies, the bars being separated to receive the points of the blanks but not admitting
the cylindrical portion of the blanks between them, substantially as described.
Dated this 19th day of November 1888.