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The
Society of Automobile
-Engineers
1451 Broadway, New York
january, 191 I
HOT ROLLED GEARS
By H. N. ANDERSON
(Member of the Society.)




Paper for Annual Meeting of the Society of
Automobile Engineers at New York City,
January II and 12, 1911.
HOT ROLLED GEARS
-- By H. N. ANDERSON.
(Member of the Society.)
Nearly four years ago, when the automobile industry was expanding
by leaps and bounds and the capacity of the machine tools was the limit-
ing feature, my attention was called to the fact that the shortage of the
gear cutting machinery seemed to be the greatest, and at that time I con-
ceived the idea of rolling the teeth in the rough blank hot, which idea
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FIG. I.-Comly Device.
upon investigation I found was not new, but had never been developed, to
a practical point. - -
DEVELOPMENT OF THE ART
The knurling process was always used theretofore, that is, either the
die was driven and the blank allowed to turn from its contact with the
die, or the blank driven and the die alloyed to turn from contact. The
idea of rolling gear teeth in a blank first originated with John Comly as
early as 1872. Comly shows the die driven and the blank rotating by
contact (Figs. I and 2). F. A. Brun, a Frenchman, in 1905, showed the















4 - Hot ROLLED GEARS.
construction illustrated in Fig. 3; the blank being driven by frictional
contact from the conical rolls 8, and the die 9 allowed to turn from con-
tact with the blank. Brun took care of the surplus metal by the adjust-
ment of the conical rolls, 8, the idea being to force this extra metal down
into the web of the gears. Chas. H. Logue, who has written a treatise
on gearing, experimented with rolling gears; but his method was to take
NSN
FIG. 2.—Comly Device
%
the blank and notch or rough it on a milling or hobbing machine, which
gave the correct number of teeth and spacing; then taking the blank, heat- .
ing it, and rolling the teeth to form. These operations would be more
expensive than cutting the teeth to size in the first place.
I then built a small machine and experimented with rolling lead
blanks, as the cold lead would flow the same as steel at a forging heat
and required but a small amount of pressure. This showed conclusively
that the tooth would form itself correctly. A large experimental ma-.
chine was then built and steel gears, samples of which I have here for
your inspection, were rolled successfully. . . . . . . .











THE SOCIETY OF AUTomoRILE ENGINEERs. 5 .
THE MACHINE
The machine in itself is very simple, as shown in the plan view. Fig.
4 comprises the driven shaft which drives through gears 14 and 12, shaft
II. On the end of shaft II is the breakdown or roughing gear 13. On
the shaft 4 is the finished gear 7; also a timing gear 6 which drives gear
23. This gear 23 is the same size as the blank to be rolled. This blank,
marked X, is held between two chucks, 24b and 27b, which are opened and
closed by a screw. The whole carriage 15, carrying chuck and gear, is
FIG. 3.-Brun Machine.
pivoted on the pivot in line with edge of gear 23, and carriage is oscil-
lated by means of screw 20 and handwheel 19.
THE PROCESS
The process is as follows: Blank X is inserted and the carriage is
thrown over toward breakdown gear 13, which does the roughing work.
This operation is very interesting, as the blank to be rolled is a little
over the pitch diameter of the gear, the metal being broken up by this
breakdown gear and “flowed” out to a larger diameter. The blank is
then brought into contact with finishing gear 7, and carried up until the
carriage reaches the stop mark 30; then the proper depth of tooth is
reached and also the proper diameter; at the same time the surplus metal
thrown out on the end of the teeth is trimmed off by cutter 31 by the
movement of carriage by screw, operated by hand wheel or lever, which

6 . HOT ROLLED GEARS.
brings edge of the gear X, in contact with cutter 31. The gear is kept
in this machine until it takes a permanent set, and is pushed off the
holding arbor by a stripping device which cannot distort it. -
The advantages of the process are: -
Ist. Cheapness, as the whole periphery of the gear is rolled in one
or two heats, depending on the size of the blank. One gets an idea of
FIG. 4.—Plan view of Anderson Machine.
the rapidity with which these gears can be made from the fact that a
gear is in the machine for a period of not over forty-five seconds.
2nd. A much stronger tooth, caused by the increased density of the
metal, as each tooth is practically forged by an enormous side pressure
on each flank.
3rd. A generated and developed tooth.
4th. The tendency to warp in case-hardening is a great deal less
than with a cut gear, as the structure of the metal at the periphery is
changed while hot and there are no internal strains to be relieved, as is

THE SOCIETY OF AUTOMOBILE ENGINEERS. 7
the case of the cut gear, the periphery of which has been changed when
the metal is cold. -
5th. Any alloy steel gear, the blank of which can be drop-forged, can
be rolled. With some silico-manganese steels which are practically im-
Fig. 6.-Operator side of Anderson Machine.
possible to machine, the blanks can have the teeth rolled and ground
afterwards if desired; the hole being ground, making all operations
forging and grinding.

8 - HOT ROLLED GEARS.
6th. As the gears are held at the periphery and the hole is bored
afterwards on a chuck which chucks from the pitch line of the teeth, the
hole must be concentric with the pitch diameter, eliminating the possi-
bility of a sprung arbor cutting an eccentric gear.
BEVEL GEARS
The rolling process applies to bevel as well as spur gears, in which
case the cost is decreased far more.
In roughing a bevel with this process, the sides of the teeth have the
true curve, with an evenly added amount of finish allowance. This is
Fig. 7-Rolled Gears.
in contrast to the ordinary roughing machine which cuts a straight side
on the teeth; the generating machine consequently having to remove more
stock in rounding the corners than on the pitch line.
FINISHING CUT
All gears where high accuracy is desired should have a finishing cut.
The process described in combination with the gear grinding machine de-
scribed by Mr. F. A. Ward, in a previous paper presented to the Society,
would give, I believe, a cheaper gear than the present gear case-hardened;
at the same time a stronger tooth and an accurate tooth. There is no
question but that, with more development of this process, gears can be used
in the lower-priced cars without any finishing cuts being required other
than running the gears in properly.
In connection with the samples, I would call your attention to the
absolute freedom of any heavy scale on the teeth.
Machines will be in operation on commercial work very shortly.
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