Improvements in "Dies for Cutting Screw-threads."
Year: 1899

page_text: Date of Application, 4th Sept., 1899-Accepted, 28th Oct., 1899
COMPLETE SPECIFICATION.
Improvements in "Dies for Cutting Screw-threads."
I, FREDERIC ELISHA WELLS, of No. 14, Congress Street, in the Town of Green-
field, in the County of Franklin and State of Massachusetts, United States of
America, Manufacturer, do hereby declare the nature of this invention, and in
what manner the same is to be performed, to be particularly described and ascer-
tained, in and by the following statement:—
This invention relates to dies for cutting screw-threads on the ends of metal-
bars, pipes, and like objects, the object being to provide a die of this class of
improved construction in respect to the cost of production and to structural
features thereof which contribute to convenience in operating the same, and to
the production of perfect threads;
And the invention consists in the peculiar construction and arrangement of
the parts of the die and in means for rigidly holding the same in operative
relations for practical use, all as hereinafter fully set forth and more particularly
pointed out in the claims.
In the drawings forming part of this specification,―
Figure 1 is a plan view of a screw-cutting die constructed according to my
invention.
Figure 2 is an edge-view of the die.
a construction
Figure 3 is a transverse sectional view of the die on line 3-3, Figure 1.
Figure 4 is a perspective view of one of the thread-cutting sections.
Figure 5 is a perspective view of one of the two side-plates of the die.
The herein described improved screw-cutting die involves
which supersedes the so-called "solid die" which has been in use for many years.
Said solid die is made from a piece of flat bar-steel of best quality, ordinarily
about two and one-half to three inches or more square, and from three-quarters
of an inch to one inch in thickness, more or less, according to the size of the
die to be produced. Said piece of bar-steel is centrally perforated and recesses
for the chips are milled out in the wall of said perforation to leave three or more
ribs therein, vertical to the sides of the die, on which the cutting screw-threads
are formed; after cutting the latter, the said threads require to be trimmed and
finished by hand-tools, to prepare them for the work for which the die is
designed;
The foregoing description of the manner of making said "solid dies" is given
in order that the marked simplicity of the improved die herein shown and
described, and the manner of making the same as compared with the former,
may be more fully understood, which improved die consists of parts which are
constructed and united to form a sectional die, possessing all of the practical
advantages and conveniences of said solid die, but costing much less to
manufacture.
Referring to the drawings, 2, 2, indicate the two side-plates of the die, which
plates, in a die for threading a bar of about one inch in diameter, are about one-
eighth of an inch thick and two and one-half inches square, and they are made
by punching them from an iron or soft steel plate, and at the same time, if
desired, forming the central opening 3 therein, the deflected abutting portions 5
and the recesses 4, extending inwardly from the border of said central opening,
Price Q71

page_text: and from the four corners of said plate, which recesses, in the finished die, receive
the border-projections a, of the thread-cutting sections 7.
The said deflected portions 5 of the said side-plates 2, tend to brace and stiffen
them, and are, in practice, so arranged as to the extent of the deflection thereof
that when the side-plates are forced upon the borders of the thread-cutting
sections 7, said deflected abutting portions will be slightly separated to the end
that when the rivets 6, are applied thereto, they will exert a continual tension
upon the plate-parts, whereby they will more tightly grasp the said thread-
cutting sections.
The parts c, of said plates, intermediate of said recesses 4, in the finished die
(see Figure 3) are forced into the recesses 8, 8, in the opposite edges of each
thread-cutting section 7.
Said thread-cutting sections are made by cutting them one by one from a flat
bar of steel, punching them to form said border-recesses 8, 8, and the border-
projections a, and then forming the cutting thread of the section on one end
thereof, the latter being completed, preferably, after the plates containing the
said sections shall have been locked together by the rivets 6, or, if preferred by
suitable screws in place of the latter, whereby, 'should occasion require, said
plates may be more conveniently separated for replacing an injured or broken
die-section with a new one.
The die, constructed as above described, has the said thread-cutting sections 7,
so rigidly interlocked with the rigidly connected side-plates 2, 2, as set forth,
that they are, practically, as immovable as are the corresponding parts of a solid
die.
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 die for cutting screw-threads comprising parallel side-plates rigidly
secured together, central oppositely located openings through each of said plates,
several thread-cutting sections occupying positions radial to said openings and
located between, and interlocking with, said plates and adapted to leave a pas-
sage between said plates and cutting sections, and connecting with said central
openings, substantially as described.
2. A die for cutting screw-threads comprising side-plates, central and oppo-
sitely located openings through each of said plates, several thread-cutting sections
occupying positions radial to said openings and located between, and interlocking
therewith, said portions of said plates between said cutting sections being
deflected toward each other, and means for rigidly securing said plates together,
at said points of deflection, substantially as described.
3. A die for cutting screw-threads comprising side-plates each having a central
opening therethrough, and several recesses therein in positions radial to the
border of said opening, and several thread-cutting sections each having the
recesses 8 and the projections a for inter-engagement with said recesses, and
with parts of said plates therebetween, and means for securing said plates together
and against said sections, substantially as described.
August,
FREDERIC ELISHA WELLS,
Signed in presence of
RUFUS A. LILLY,
WILLIAM H. WARD.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.