Improvements in Gear Wheels and a Method of and Apparatus for Manufacturing the same.
Year: 1892

page_text: Date of Application, 21st Mar., 1892
Complete Specification Left, 13th Dec., 1892-Accepted, 18th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in Gear Wheels and a Method of and Apparatus for
Manufacturing the same.
I, ELIPHALET WILLIAMS BLISS, a citizen of the United States, residing in
New Utrecht, in the County of Kings and State of New York, United States of
America, Manufacturer, do hereby declare the nature of this invention to be as
follows:-
Cast
Metal gear wheels are now commonly made by either casting or cutting.
metal gears are subject to the defects inherent in cast metal, the better grade of
gears being made of wrought metal, and the teeth formed by cutting or milling out
the spaces between them from the solid metal. Such gears are very expensive,
and are somewhat weakened by the cutting process which severs the grain of the
metal.
My invention provides an improved gear of wrought metal wherein the teeth are
formed by compression so that the metal is caused to flow and the grain of the
metal is continuous instead of being interrupted as in cut gears.
A block or billet
of wrought metal, preferably steel, is heated to the proper temperature, and
is placed in a die the inner surface of which is formed with teeth conforming to
those to be formed on the gear wheel. A male die or punch is then forced into the
female die by hydraulic or other suitable pressure, whereby the wrought metal is
squeezed and forced into the spaces between the teeth of the female die filling the
latter completely and being compressed so as to present a homogeneous mass of
metal. The block of metal which has been thus converted into a gear is then
forced out of the female die, and after cooling it is bored out, and if necessary
dressed up
in a gear cutter to smooth the surfaces of the teeth. The gear thus.
made has the grain of the metal flowing from the body of the gear into the
respective teeth without interruption, so that its teeth are much stronger and less
liable to break off than with cut gears. At the same time it retains every advantage
that wrought gears have over those made of cast metal.
Figs. 1 and 2 of the accompanying drawings show a gear or pinion made
according to my invention;
Fig. 3 is a plan of one form of female die such as may be used in making these
gears;
Figs. 4, 5 and 6 are vertical sections of the dies showing the successive operations
of making the gear ;
Fig. 7 is a fragmentary plan of the gear on an enlarged scale showing approxi-
mately the direction of the grain of the metal.
The gear A shown in Figs. 1 and 2 does not differ materially in appearance from
ordinary cut gears, but differs essentially therefrom in the direction of the grain of
the metal, which by reason of the pressure has been distorted and forced to flow
into the teeth in lines following the outlines of the teeth and more or less parallel
therewith, as shown approximately in Fig. 7. By reason of the uninterrupted grain
of the metal, the gear teeth are much stronger than in cut gears, wherein the grain
of the metal is necessarily interrupted by cutting out the spaces between the teeth.
The metal of the gear is also more compact and tougher than that of ordinary cut
gears by reason of the heavy hydraulic pressure to which it has been subjected.
The surfaces of the teeth are especially much more dense than in ordinary cut gears,
since the metal has been forced into such intimate contact with the inner surfaces of
the die, thereby forming as is believed a comparatively tough and hard skin or layer
by reason of the pressure, and perhaps also of the chilling effect of the comparatively
アイ

page_text: cool die. In consequence, my improved gear is not only stronger than any heretofore
made, but there is reason to believe that it will also prove more durable.
In order to enable those skilled in the art to produce gears according to my
invention, I will describe one method by which they may be made, although I do
not confine myself to any method of or apparatus for making these gears.
Referring to Figs. 3 to 6, let B designate the bed or table of a hydraulic press,
and C a female die embedded therein having internally formed gear teeth con-
forming to those to be made ou the gear. The bottom of this die is closed by a
slide D, which should be made with parallel sides, and with a slightly wedge-shaped
bottom, so that when driven in its upper surface shall be forced up firmly against
the under side of the die. The male die or punch E is fastened to the upper
member or ram F of the press, and is formed with external teeth which are counter-
parts of those on the gear to be made. Both the male and female dies, however,
should be of greater height than the length of the gear. The block or billet of
steel or other metal should be of such diameter as to easily drop into the lower
die, for example, as shown by the dotted circle x in Fig. 3, and should be of a
height somewhat greater than the length of the finished gear, in order to provide
sufficient metal for lateral expansion into the teeth of the die. In Fig. 4 this
billet is shown at A' as having been placed in the female die and the male die
being brought down upon it. Fig. 5 shows the completion of the compressing
operation. The male die has forced the metal A¹ to flow laterally and completely
fill the female die. After sufficient pressure has been thus exerted, the male die is
lifted slightly to relieve the pressure on the slide D, whereupon the latter is driven
out and the male die is again brought down to force the metal block or gear A¹
out through the open bottom of the die as shown in Fig. 6. The pressed gear thus
made drops out through the bed of the press, and upon cooling is ready to be bored
and formed with a keyway as shown in dotted lines at b in Fig. 1. If necessary it
may be put in a gear cutter and given a light finishing cut to make its teeth more
accurate, but if the female die C is made with its teeth very smooth and accurately
cut, and with the proper allowance for the shrinkage of the metal in cooling, this
finishing cut will not be necessary, as the surface of the teeth of the gear will be
made very smooth and hard, and will receive a further polish in the act of forcing
it out of the female die.
Although steel is the preferable metal for making my improved gears, yet other
metals may be employed, as for example wrought iron, phosphor bronze, etc.
Dated this 21st day of March 1892.
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.
COMPLETE SPECIFICATION.
Improvements in Gear Wheels and a Method of and Apparatus for
Manufacturing the same.
I, ELIPHALET WILLIAMS BLISS, of New Utrecht, in the County of Kings and
State of New York, 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 ascertained in and by the following
statement:-
Metal gear wheels are now commonly made by either casting or cutting. Cast
metal gears are subject to the defects inherent in cast metal, the better grade of
gears being made of wrought metal, and the teeth formed by cutting or milling out
the spaces between them from the solid metal. Such gears are very expensive,
and are somewhat weakened by the cutting process which severs the grain of the
metal.

page_text: My invention provides an improved gear of wrought metal wherein the teeth are
formed by compression so that the metal is caused to flow and the grain of the
metal is continuous instead of being interrupted as in cut gears.
A block or billet
of wrought metal, preferably steel, is heated to the proper temperature, and is
placed in a die the inner surface of which is formed with teeth conforming to those
to be formed on the gear wheel. A male die or punch is then forced into the
female die by hydraulic or other suitable pressure, whereby the wrought metal is
squeezed and forced into the spaces between the teeth of the female die filling the
latter completely and being compressed so as to present a homogeneous mass of
metal. The block of metal which has been thus converted into a gear is then
forced out of the female die, and after cooling it is bored out, and if necessary
dressed up in a gear cutter to smooth the surfaces of the teeth. The gear thus
made has the grain of the metal flowing from the body of the gear into the
respective teeth without interruption, so that its teeth are much stronger and less
liable to break off than with cut gears. At the same time it retains every advantage
that wrought gears have over those made of cast metal.
Figs. 1 and 2 of the drawings filed with my Provisional Specification show a
gear or pinion made according to my invention;
Fig. 3 is a plan of one form of female die such as may be used in making these
gears;
Figs. 4, 5 and 6 are vertical sections of the dies showing the successive operations
of making the gear;
Fig. 7 is a fragmentary plan of the gear on an enlarged scale showing
approximately the direction of the grain of the metal.
Referring to the said drawings:
The gear A shown in Figs. 1 and 2 does not differ materially in appearance
from ordinary cut gears, but differs essentially therefrom in the direction of the
grain of the metal, which by reason of the pressure has been distorted and forced
to flow into the teeth in lines following the outlines of the teeth and more or less
parallel therewith, as shown approximately in Fig. 7. By reason of the uninter-
rupted grain of the metal, the gear teeth are much stronger than in cut gears,
wherein the grain of the metal is necessarily interrupted by cutting out the
spaces between the teeth. The metal of the gear is also more compact and
tougher than that of ordinary cut gears by reason of the heavy hydraulic
pressure to which it has been subjected. The surfaces of the teeth are especially
much more dense than in ordinary cut gears, since the metal has been forced into
such intimate contact with the inner surfaces of the die, thereby forming as is
believed a comparatively tough and hard skin or layer by reason of the pressure,
In con-
and perhaps also of the chilling effect of the comparatively cool die.
sequence, my improved gear is not only stronger than any heretofore made, but
there is reason to believe.that it will also prove more durable.
In order to enable those skilled in the art to produce gear wheels according to
my invention, I will describe one method by which they may be made, although I
do not confine myself to any method of or apparatus for making these gear wheels.
Referring to Figs. 3 to 6, let B designate the bed or table of a hydraulic press,
and C a female die embedded therein have internally formed gear teeth conforming
to those to be made on the gear. The bottom of this die is closed by a bottom
plate or slide D, which should be made with parallel sides, and with a slightly
wedge-shaped bottom, so that when driven in its upper surface shall be forced up
firmly against the under side of the die. The male die or punch E is fastened to
the upper member or ram F of the press, and is formed with external teeth which
Both the male and female dies,
are counterparts of those on the gear to be made.
however, should be of greater height than the length (width) of the gear. The
block or billet of steel or other metal should be of such diameter as to easily drop
into the lower die, for example, as shown by the dotted circle x in Fig. 3, and should
be of a height somewhat greater than the length of the finished gear, in order to
I

page_text: provide sufficient metal for lateral expansion into the teeth of the die. In Fig. 4
this billet is shown at A! as having been placed in the female die and the male die
being brought down upon it. Fig. 5 shows the completion of the compressing
operation. The male die has forced the metal A¹ to flow laterally and completely fill
the female die. After sufficient pressure has thus been exerted, the male die is lifted
slightly to relieve the pressure on the slide D, whereupon the latter is driven out
and the male die is again brought down to force the metal block or gear A' out
through the open bottom of the die as shown in Fig. 6. The pressed gear thus
made drops out through the bed of the press, and upon cooling is ready to be bored
and formed with a keyway as shown in dotted lines at 6 in Fig. 1. If necessary it
may be put in a gear cutter and given a light finishing cut to make its teeth more
accurate, but if the female die C is made with its teeth very smooth and accurately
cut, and with the proper allowance for the shrinkage of the metal in cooling, this
finishing cut will not be necessary, as the surface of the teeth of the gear will be
made very smooth and hard, and will receive a further polish in the act of forcing it
out of the female die.
Although steel is the preferable metal for making my improved gears, yet other
metals may be employed, as for example wrought iron, phosphor bronze, etc.
I am aware that watch pinions have been formed integrally with their staffs by
cutting soft or untempered steel wire of the diameter of the staff to the proper length
and placing it while cold between dies which engage its ends, and forcing these dies
together to upset the middle portion of the wire, thereby expanding it to fill a
chamber or matrix in one of the dies formed with internal teeth corresponding with
the teeth of the pinion, the male die being constructed to move down against but not
to enter the female die. The making of minute gears such as watch pinions in this
manner, is to be clearly distinguished from my invention, which is designed for
making large, heavy and massive gear-wheels such as are used in large machinery,
and in which a block of hot metal nearly as large as can be placed in the female
die within the teeth thereof, is subjected to the extremely heavy pressure of a
hydraulic press or other equivalent means for generating the requisite pressure, the
pressure being transmitted through a male die which enters within the matrix or
chamber of the female die, the pressure being so heavy as to cause the hot metal to
flow outwardly and enter and fill the teeth of the die, and by the extremely heavy
pressure to be thoroughly compacted or compressed, so that the teeth are given a
hard, and if need be, a finished or polished surface.
Having thus particularly described and ascertained the nature of my said
invention and in what manner the same to be performed, I declare that
what I claim is :-
1. A gear wheel of wrought metal having the characteristics substantially as
herein before specified.
2. A gear wheel of compressed surface-chilled wrought steel having its cog
teeth formed by compression with the grain of the metal distorted into the teeth,
substantially to the effect specified.
3. The method of making wrought gear wheels consisting of placing in a female
die having internal gear teeth a block of heated metal nearly filling the said die
within the teeth thereof, and causing it to expand or flow outward to fill the teeth
of the die by pressure communicated through a male die entering said female die,
substantially in the manner and to the effect specified.
4. The method of making wrought gear wheels consisting in placing a block of
heated metal in a female die having internal gear teeth expanding it to fill said die
by pressure communicated through a male die, and finally forcing it out through
the female die, substantially in the manner and to the effect specified.
5. The improved apparatus for making compressed wrought metal gear wheels
comprising a bottomless female die having internal gear teeth, a toothed male die
adapted to enter within said female die, and a removable bottom plate beneath the

page_text: female die, combined with a hydraulic press or other equivalent means for forcing
the dies together with the requisite heavy pressure, substantially in the manner
specified.
Dated the 12th day of December 1892
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.