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Патент USA US2139290

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Dec. 6, 1938.
v w. F, SLQMER
‘ Filed Sept. 25, 1933
2 Sheets-Sheet 1
Maw?’ '
Dec. 6, 1938.
Filed Sept. 25, 1933
2 Sheets-Sheet 2 ‘ a
' Patented Dec. 6,1938
. 1 2,139,290
William F. Slomer, Detroit,,Mich., assignor to
The Fellows Gear Shape: Company, Spring
?eld, Vt., a corporation of Vermont
I Application September 23, 1933, Serial No. 690,715
"1' Claims.
. This invention relates to the art of ?nishing
gears by lapping and analogous procedures, ac
cording to which the gear to be ?nished is run in
(on. 51-26)
the results above described may be accomplished
by grooving circumferentially and centrally one or '
more (but not all) of the master gears or tools
mesh with conjugate master gears of predeter
5 mined characteristics and dimensions until
brought to the prescribed accuracy and perfection
of form, dimensions and surface finish; In the
course of carrying out the treatment above 'de
used for gear lapping; and the invention for which
I claim protection consists .in the industrial 5
utilization of this discovery in tools having a suit
able grooved formation and the combination of
such a tool or tools with ungrooved tools, and in
m scribed two or more master gears are usually'pro
the procedure of treating gears with the aid of
'vided for simultaneous mesh with the work piece ‘ such tools.
and either the work piece or one of the master
gears may serve as the driver; the pressure ap
plied in then overcoming the resistance of the
driven gear, which resistance may be augmented
'15 by a brake if desired, providing whatever pressure
is needed between the contacting faces of the
Referring to the drawings,—
Fig. 1 is a diagrammatic elevation of a se
of gearlapping tools in association with a gear
being lamied, containing the mechanical features,‘
and being operated in accordance with the method
phase, of this invention;
master gears or tools and the work to perform
Fig. 2 is a vertical section taken on line 2--2
the effect required on the work. It is also the - of Fig. 1; and shown on an enlarged scale;
common practice to reciprocate the work piece
Fig. 3 is a cross section taken on the broken line
20 axially at a more or less rapid rate during rota
3--A—3 of Fig. 1;
tion in order better to distribute the e?ect.
Fig. 4 is a diagrammatic perspective view show
The object of the present invention is to pro
ing illustratively suitable ‘mechanical means for
vide means capable of not only ?nishing gears in imparting the necessary movements of rotation
the manner above described but also of giving a and axial reciprocation to the work and tools;
25 crowning formation to the gear teeth at the same
Like- reference characters designate the same 25
time. It has been recognized in the mechanical parts wherever they occur in all the ?gures.
arts in which gears are used, ‘and particularly
In these drawings, W represents the work piece,
in the automobile art, that if gears could be made
with teeth crowning from end .to end, that is,
30 with greater thickness in the middle portion than
at the ends, and with a generally convex longi
tudinal curvature at their faces, distinct ad-:
that is, a gear wheel or pinion of any character '
capable of being ?nished by lapping; and T’, 'I‘2
and T3 represent three lapping tools, which are
master gears of suitable pitch, tooth spacing, ' and _
pressure angle, to mesh with and perform the re
vantages would result therefrom._ Attempts have
quired lapping action on the work piece. In ac
been made to produce gears of such crowning
cordance with common practice these master
gears are here shown as being of larger diameter 35
35 tooth formation in various ways and with greater
or less measure of success. The purpose of my in
vention is to provide an exceedingly simple means
of obtaining this result. I have discovered a
radically novel means and methodfonobtaining
40 the desired crowning e?ect, which has the practi
cal advantage of extreme simplicity and of in
volving no additional'step or operation in the gear
?nishingprocedure, nor any increase in the cost
than the work piece; and the work piece is re
ciprocated axially at the same time that it is ro
Although the invention involves nothing new
in'the principles of the machine by which the
tools and work piece are supported and driven, I
have deemed it advisable by way of illustration
ried out in connection with the ordinary process
to‘ show the main features of a machine suitable
for the purpose. Such a machine is shown ‘in
Fig. 4. The work piece is mounted on a tele
of lapping, and when so carried out results in
scopic shaft consisting of the rotatable driving
teeth having faces which to all intents and pur
section S’ and the enveloping sleeve section 8*,
such sections being splined together. The tools
are mounted on parallel shafts S3, S4 and S5,
mounted to turn in their bearings when driven by 50
the work piece meshing with the tools, and being
equipped if desired with‘any' suitable form of
brake to increase theirresistance to rotation and
consequently the pressure exerted by their tooth
faces on those of the work piece. For clarity of 55
of ?nishing a gear.
The procedure can be car
' Poses are crowned with a substantially uniform
convexity from end to end and with a su?lcient
50 degree of convexity and difference of thickness at
points spaced apart from end to end, to givethe
desired freedom of mesh with companion‘ gears
and automatic compensation for a. moderate de
gree of misalinement of the gears.’
The basis of the invention is my discovery that
illustration the tool 'I? and its shaft 84 are shown , ing end of the work piece still remains wholly
only by‘dotted lines in this view. A motor M or partly. across the groove. It is preferable also,
drives by a belt and pulley gearing P, B and P‘, if not absolutely essential, that the limits of the‘
a power shaft S6 which drives the shaft section S’ groove be in planes perpendicular to the axis of
through helical gears G’, G’, and so drives the . the tool.
work piece, which in turn drives the master gears
or tools. Gear G’ drives a second helical gear G3
on shaft S", and the latter drives a shaft Sa
through helical gears G4, G5. The latter shaft
10 carries a crank pin 0 which oscillates a rock shaft
Each active part above referred to of the
grooved tool may be considered as itself~a tool
operating on the work piece teeth from one end
to points short of the other -'end; the material
of' the tool inside of the groove being a connect 10
R by means of a connecting rod C’ and rock arm , ing element which prevents either active portion
R’, ‘thereby oscillating a gear segment G6 which
meshes with a circular rack Cr on the telescopic
shaft section 82 and so reciprocates the work
It will be understood that the parts may be so
proportioned as to give any desired extent of
reciprocation to the work piece and that' the tools
may be made with any desired width of‘face,
from shifting out of register with the work piece
while the latter meshes only with the other active
The same principles and substantially identical 15
means are equally applicable to producing
crowned helical gears as well as spur gears; by
using helical master gears as the lapping tools.
What I claim and desire to secure by Letters
20 while the ratio of reciprocative speed to rotative Patent is:
' v
speed ‘of the work may be made of any. desired ~ 1. The method of ?nishing gear teeth with a
In carrying into e?ect my present invention I
provide at least one of the lapping tools with a
25 circumferential groove.
As a matter of fact in
the present illustration two of the tools,-namely,
T’ and T3 are thus grooved, the groove for the
tool.T' being‘ shown at U’ in Fig. 3, and that of
the tool T3 being shown at U:‘ in Fig. 2. Both
30 grooved tools are also shown in Fig. 4. These
grooves are located in the outer circumference
of their respective tools and in the zone approxi
mately midway between the ends of the tool.
The width of the groove is determined in'pro
portion to, the width of the tool (or rather the
length of the tool‘ in its axial direction), the
length of the work piece; and the extent of re
crowning formation which consists in rotating
the gear tobe ?nished in mesh with a plurality
of master gear laps, one of such laps being ‘formed
to limit the bearing of its teeth on the 'work'to 25
the end portions of both sides of such teeth, and‘
. with 'an interruption of bearing on their-mid
portions, while the othertool has substantially
continuous bearing contact'from end to end of
its teeth, and reciprocating the work piece axially
in a path which causes its teeth to_ be engaged
mainly at the end portions with one of the tools
and at both ends and middle portions with the
other tool.
2. A gear lapping apparatus comprising I a 35
series of master gears adapted to make simul
taneous meshing engagement with a work piece,
ciprocating motion of‘ the work piece so that the one of said tools having an enveloping groove
lapping action of the grooved tool will be limited ‘intersecting its teeth lintermediate' their ends,
or concentrated to the ends of the work piece with (and means for reciprocating the workpiece
no’ action, or a less action, at the middle of the equally to opposite sides of a mid position where 40
work piece and progressively greater action from in its middle zone coincides with such. groove:
the middle to both ends. In this illustration the said reciprocating means being organized to'limit
tools are about twice as wide, and the grooves ' the travel‘ of the work piece to a distance less
about half as wide-as the work piece; while the* than the full length of its teeth in either direction
workpiece is reciprocated between limits co
from such mid position.
inciding approximately with the end planes of
3. A gear ?nishing apparatus comprising a
the tools, indicated by dotted lines in Figs. 2sand series of ,master gears arranged for simultaneous
3. But at least one of the tools, as T‘, has no' meshing engagement with a centrally located’
groove and acts uniformly over the whole length work piece, and means for reciprocating a work
of the'work piece. .
piece in simultaneous mesh with said ‘master 50
_ It is within my-contemplation to groove only gears, one of the gears having a circumferential
' one of the tools; and also to provide grooves of groove intersecting its teeth intermediate their
different widths in different tools, when two or ' ends, and said , reciprocating means being
more of the toolsv are grooved. The absolute
width of the groove is a value which may be»
varied considerably, a's-may be also the length
.of reciprocative. movement of the work, and the
other dimensions‘ of the work and tools. By
properly selecting these dimensions and ‘values
desired e?’ects, within wide limits, of crowning
the teeth of the work piece may be secured and
work turned out of which the teeth are Per
- ceptibly thicker at the middle than at the ends
with a gradual diminution of thickness from
the middle to. the ends and withoutabrupt steps
between zones of di?erent thicknesses. To obtain
these eifects it is necessary that the relation be
tween the- length of reciprocative travel, the
70 length of the-work piece teeth, and the length
of-the active parts of the tool on opposite sides
,iofuthe groove be such that less than the whole
lengtliof the 'work piece teeth be traversed across
either active part of the tool; in other words,
v. u
organized to arrest the work piece at each end of
its'travel with its following endoverlapping the (
4. A gear ?nishing apparatus comprising .a
series of master gears arranged for simultaneous
meshing engagement with a centrally located
work piece, means for rotating, and means for
reciprocating a work piece in simultaneous mesh _ '.
with said' master gears, two of the gears'each
having a',circumferential groove intersecting its
teeth intermediate their ends, .and said recipro 66
cating means being organized to arrest the work
piece at eachv end of its travel with its following
end overlapping the groove.‘
. .
'5. A gear ?nishing apparatus comprising a
series'of master gears arranged for simultaneous 70
meshing engagement with a centrally located
work piece, means for supporting and recipro
cating a work piece in simultaneous mesh with
said master gears, two of the gears each having
that the reciprocation be arrested while the trails‘ a circumferential groove
its teeth 76
intermediate their ends, and one of said grooves
being of greater width than the other, and said
reciprocating means being organized to arrest the
work piece at each end of its travel with its
following end overlapping the groove.
the middle thereof, simultaneously on opposite
sides of each tooth in turn.
'1. The method of finishing gears with teeth of
crowning formation which consists in running
such teeth in mesh with a master gear tool, e?ect
6. The method of ?nishing gears with teeth of = ing relative axial reciprocation between the work
crowning formation which consists in running * piece and tool, and limiting the extent of contact
such teeth in mesh with a plurality of master
gear lapping tools, effecting relative axial re
between the tool and work so that the action of
the tool is applied with greater concentration
at and .ne'ar the ends than at the middle part 01 10
causing one tool to act substantially uniformly the teeth being ?nished simultaneously on op
. over the whole length of the teeth being ?nished, posite sides of each tooth in turn.
and causing‘ another tool to act with greater
e?ect at and-near the ends of said teeth than at
10; ciprocation between the work piece and tools,
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