Improvements in Screw Cutting Taps and Dies.
Year: 1885

page_text: Improvements in Screw Cutting Taps and Dies.
We EDWARD COPE of High Bank Steel Works, Openshaw in the county of
Lancaster Nut and Tube Manufacturer and ALFRED HOLLINGS of the same place
Works Manager do hereby declare the nature of the said invention for IMPROVE.
MENTS IN SCREW CUTTING TAPS AND DIES to be as follows:-
☐ The object is to so form taps and dies for cutting screw threads, in nuts and on
bolts that the metal shall be removed in flakes rather than in strips thus reducing
the resistance against, the cutting edges and, greatly increasing the durability
especially when used in the formation of nuts and bolts of mild steel or like
tenacious, metal.
.1
The invention consists in forming taps and dies with a thread of uniform
diameter and pitch as regards the bottom of the said thread and of uniform pitch
and decreasing or increasing diameter as regards the tops of the threads such
threads having more and more obtuse angles as they approach that portion of the
tap or die which first acts on the nut or bolt.
When a long tap or die is used part of the threads are of uniform diameter
throughout in order to secure a finished thread.
When two or more taps or dies are used in the formation of a thread one may
advantageously be made with the tops of the threads of a decreasing or increasing
diameter throughout and another with a portion of its length cylindrical.
Dated this 25th day of June 1885
:

page_text: Improvements in Screw. Cutting Taps and Dies.
We EDWARD COPE of High Bank Steel Works Openshaw, in the County of
Lancaster Nut & Tube Manufacturer, and ALFRED HOLLINGS of the same place
Works Manager, 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 :—
The object is to so form taps and dies for cutting screw threads in nuts and on
bolts that the metal shall be removed in flakes rather than in strips thus reducing
the resistance against the cutting edges and greatly increasing their durability
especially when used in the formation of nuts and bolts of mild steel or like
tenacious metal.
The invention consists in forming taps and dies with a thread of uniform
'diameter and pitch as regards the bottom of the said thread and of uniform pitch
and decreasing or increasing diameter as regards the tops of the threads, such
threads having more and more obtuse angles as they approach that portion of the
tap or die which first acts on the nut or bolt.
When a long tap or die is used part of the threads are of uniform diameter
throughout in order to secure a finished thread.
When two or more taps or dies are used in the formation of a thread, one may
advantageously be made with the tops of the threads of decreasing or increasing
diameter throughout, and another with a portion of its length cylindrical.
.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is an elevation, and fig. 2 a plan of a tap constructed under my invention
for making finished screw threads in nuts or other hollow articles. The threads
are of uniform diameter and pitch at the bottom along the whole length of the tap
as shown at a. As regards the top of the threads they are of uniform pitch
throughout but increase in diameter from 6 to c; from c to d the tap is cylindrical
e longitudinal groove. As shown the result of this construction is that the threads
gradually change from very obtuse angles to acute angles.
Figs. 3. and 4. show two taps constructed to work in conjunction for forming a
complete screw thread. In fig. 3 the diameter gradually increases throughout,
in 4 the diameter increases from b to c and is cylindrical from c to d. Taps under
our invention may be made solid or with a round hole therethrough, or with
a hole following the configuration of the metal in transverse section as shown
in fig. 2.
Fig. 5 is a section, and fig. 6 a plan of a die constructed under our invention,
here the tops of the threads decrease in diameter from b to c, and are cylindrical
from c to d.
Taps and dies under our invention are cut when in a lathe or like machine by
combs and other tools of suitable shape for leaving the threads with the angles
and dimensions described.

page_text: Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
First. Taps and dies constructed substantially as herein set forth for cutting
Screw threads.
Second. Taps constructed with the bottoms of the threads of uniform diameter
and pitch, and the tops of the threads of uniform pitch and increasing diameter.
Third. Dies constructed with the bottoms of the threads uniform in diameter
and pitch and the tops of the threads uniform in pitch and of decreasing diameter.
Dated this twenty seventh day of Anril 188k
J. T. KING,
Per J. Johnson, Agent.