CA2088336A1 - Cold-forming of toothed wheels from sheet steel - Google Patents
Cold-forming of toothed wheels from sheet steelInfo
- Publication number
- CA2088336A1 CA2088336A1 CA 2088336 CA2088336A CA2088336A1 CA 2088336 A1 CA2088336 A1 CA 2088336A1 CA 2088336 CA2088336 CA 2088336 CA 2088336 A CA2088336 A CA 2088336A CA 2088336 A1 CA2088336 A1 CA 2088336A1
- Authority
- CA
- Canada
- Prior art keywords
- tooth
- cold
- forming
- teeth
- preform
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 10
- 239000010959 steel Substances 0.000 title claims description 10
- 239000002184 metal Substances 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 40
- 238000005096 rolling process Methods 0.000 claims abstract description 8
- 230000001360 synchronised effect Effects 0.000 claims abstract description 6
- 230000002093 peripheral effect Effects 0.000 claims description 21
- 230000008719 thickening Effects 0.000 claims description 10
- 239000007787 solid Substances 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 3
- 238000005097 cold rolling Methods 0.000 claims 4
- 239000007858 starting material Substances 0.000 description 11
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- 102100034742 Rotatin Human genes 0.000 description 1
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- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
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Landscapes
- Forging (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method of forming a one-piece sheet metal toothed wheel comprising the steps of rotating (1) a rotary holding unit with the preform secured thereto about the preform axis and an inner portion of an outer annular section of the preform within a back-up space provided by the holding unit, and (2) a tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and the rotational speeds are synchronized, and then while the rotary holding unit with the preform secured thereto and the tooth-forming tool unit are in the predetermined rotational relation affecting relative movement between the units and the axes thereof in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperation metal-deforming relation with the outer portion of the outer annular section inwardly of the exterior periphery the preform until the sheet metal of the outer portion of the annular section is cold-formed into the series of teeth and displaced from the troughs therebetween so that after the series of teeth are cold-formed the toothed wheel includes a back-up portion having surfaces conforming to the back-up space, the peripheries of the series of teeth being cold-formed by rolling contact with the tooth-forming periphery of the tooth forming tool unit and the sides of the series of teeth including portions disposed outwardly beyond the spaced tooth side defining planes being free-formed without surface, contact by the axially outward movement of the metal defining the outer portion of the outer annular section.
A method of forming a one-piece sheet metal toothed wheel comprising the steps of rotating (1) a rotary holding unit with the preform secured thereto about the preform axis and an inner portion of an outer annular section of the preform within a back-up space provided by the holding unit, and (2) a tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and the rotational speeds are synchronized, and then while the rotary holding unit with the preform secured thereto and the tooth-forming tool unit are in the predetermined rotational relation affecting relative movement between the units and the axes thereof in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperation metal-deforming relation with the outer portion of the outer annular section inwardly of the exterior periphery the preform until the sheet metal of the outer portion of the annular section is cold-formed into the series of teeth and displaced from the troughs therebetween so that after the series of teeth are cold-formed the toothed wheel includes a back-up portion having surfaces conforming to the back-up space, the peripheries of the series of teeth being cold-formed by rolling contact with the tooth-forming periphery of the tooth forming tool unit and the sides of the series of teeth including portions disposed outwardly beyond the spaced tooth side defining planes being free-formed without surface, contact by the axially outward movement of the metal defining the outer portion of the outer annular section.
Description
2 ~ 6 COLD-FORMING OF TOOT~ED WHEELS FROM SElEhT STE:EL
This invention relates to toothed wheels of the type utilized in motor vehicles as, for example, in the starter assembly thereof and more particularly to improvements in the method of making such toothed wheels.
In my prior United States Patent No. 5,152~061, there is disclosed a method of forming a ~oothed wheel including a series of cold-formed peripheral teeth having sides spaced apart a predetermined distance utilizing (1) a rotary holding unit having structure providing a generally radially outwardly facing control surface and (2) a rotary tooth-forming tool unit having a rotational axis and a tooth-forrning periphery extending annularly about the rotational axis. One of the rota~y units includes two annular flanges extending outwardly thereof baving two smooth tooth-side forming surfaces facing toward one another spaced apart the predetermined distance. The method of the '061 patent comprises the initial step of cold-forming a circular piece of sheet metal of predetermined thickness into a preform having an outer annular section of generally uniform cross-sectional configuration and an . ~.
, ~ integral sheet metal central wall generally of the predetermined thickness extending annularly inwardly from the outer annular section toward a pre~orm axis, the outer ;
annular section having (l) a width greater than the ' .
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predetermined thickness but no greater than the predeterminad distance, and (2) a~ outer periphery which will allow a ~eshing action with the tooth-formin~ periphery of the tooth-forming tool unit. The method of the '061 patent also includes the step of rotatin~ (1) the rotary holding unit with the preform secured thereto about the preform axi~ and : with the control surface underlying at least a portion 10 of the annular section and (2) the tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and the rotational speeds are synchroni~ed.
While the rotary holding unit with th~ preform secured thereko and the tooth-forming tool unit are in the predetermined rotational relation, the method of the '061 patent further includes the ~tep of affecting a relative movement between the units and the axes thereof in a direction toward one another to engage the tooth-formirlq periphery of the tooth-: forming tool unit in cooperating metal-deforming relation with the annular section inwardly of the exterior periphery thereof until the sheet metal of the annular section is cold-formed into the series of teeth, the peripheries of which are cold-formed by rolling contac~ with the tooth-forming periphery of , . the tooth-forming ~ool unit and portions of the sides of which are smooth and cold-formed by contact with the smoo~h too~h-side forming sur~ace so that an amount of sheet metal which would otherwise uncontrollably flow axially outwardly of the ~mooth tooth-side ~orming sur~ace~ i~ conaentrated within the teeth and/or the radially inward back-up thare~or.
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It has been found that, while the total confinement o the metal during the cold-forming operatlon has the advantages stated, there also existed a tendency to break teeth off of the rotary tooth-forming tool unit after a period of operation which, on occasion, would be substantially less than the normal ~xpected operative life of the tool unit.
The frequency of tooth failure was considered unexpected particularly in the tool construction where tha two annular flanges for forming the two ~mooth tooth sides were integrally interconnected on opposite side~ of the ~orming teeth.
An object of the present invention is to overcome the problem of frequency of tooth failure in the ro~ary tooth ~orming.unit of the above described method of the '061 patent. In accordance with the principles of the present invention this objective is achieved by providing a method of ~orming a one-piece sheet metal toothed wheel includin~ a central sheat metal wali of predetermined thickness and a series of cold-~ormed inteqral teeth on the periphery of the central wall defined by troughs extending radially inwardly therebetween to a cylindrical trough plane concentric with an axis of the central wall, the series o~ cold~formed integral teeth having an op~rative width de~ined by spaced tooth side defining planes. The method utilizes ~1) a rotary holding unit which in holding operation provides an inner pair of opposed central wall-engaging surfaces extending generally radially outwardly to a cylindrical inner plane ~paced inwardly ~rom an outer cylindrical plane of a size equal to the trough plane and an outer pair -- - ., .. .. . . ... .. .. - . ..... . .. . . .... . ... . ..
.:.. - , .: .. ,: :,. , .:,, . : .:: .:.. . . ..... :. :.: . , . ~ :. : ,. :
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of back-up suraces extending from the inner pair of opposed central wall-engaging surfaces at the inner : plan~ to the outer plane where the outer pair of ~urfaces are spaced apart a predetermined distance which i~ greater than the spacing between the inner palr of aurfaces so as to define a back~up sp~ce within an annulus between the inner and outer planes a~d (2) a rotary tooth-formin~ tool unit having a rotational axis and a tooth-forming periphery ~o extending annularly about the rotational axi~. The method c~mprises a combin~tion of steps the initial one o~ which is cold-forming a circular piece of sheet metal into a preform having an outer annular section of generally uniform cross-sectional coniguration and an integral sheet metal central wall qenerally of the predetermined thickness extending generally radially inwardly from tha outer annular section toward a prerorm axis. The outer annular section has (l) a width greater than the predetermined thickness but no greater than the predetermined distance, and (2) an outer periphery extending beyond the trough plane which will allow a meshing action with the tooth-forming periphery o~ the tooth-forming tool unit. The next step is rotating (1) the rotary holding unit with the prefor~ secured thereto about the preform axis and an inner portion of the outer annular section within the back-up space and an outer portion of the outer annular section extending radially outwardly o~ the back-up space, and (2) the tooth-forming tool unit 30 . about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and the rotational ~peeds are synchronized. ~he third step is per~ormed while th; rotary holding unit with .
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the preform secured thereto and the tooth-forming tool unit are in the predetermined rotational relation affecting a relative movement between the uniti and the axes thereof in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperating metal-deforning relation with the outer portion of the outer annular section inwardly of the exterior periphery thereo~
until the sheet metal o~ the outer portion of the ainnular section is cold formed into the series of teeth and displaced ~rom the troughs therebetween so that after the series of teeth are cold-formed the toothed wheel includes a back-up portion having - surfaces conforming to an outer extent of each o~ the outer pair of ~iur~ace defining the back-up space, the peripheries of the series of teeth being cold-formed by rolling contact with the tooth-forming periphery of the tooth-forming tool unit and the sides of the series of teeth ihcluding portions disposed.outwardly beyond the spaced tooth side defining planes being j free formed without surface contact by the axial~y outward movement of the metal defining the outer porti~n of the outer annular section.
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Prefera~ly, the rotary holding tool unit further provides a pair of cylindrical extarior peripheral sur~aces extending axially in opposite directions from the outer pair of surfaces within the outer plane and the tooth formin~ periphery of the tooth ~orming tool unit includes trough forming teeth-like projections having exterior tips which extend toæaid trough plane. Pre~erably, in the third step, at th~ end of the relative movement between the units 208~3~
, . . .
~owards one another to engaqe the tooth forming periphery of the ~oo~h forming tool unit in cooperating relation with the outer portion of the outer annular section, the tips substantially engage the exterior periphery sur~aces of the rotary holding unit.
Preferably, the spaced tooth side def~ning planes pas~ generally through the outer pair of surfaces spaced apart within ths outer plane.
Preferably, the method includes a ~ourth step which is the machinlng of the free-formed portions of the sides of the series o~ teeth at least along one common side so that the machined ~ides of the teeth on the one common ~ide are disposed in a co~mon plane constituting one of the spaced tooth si~e dePining planes.
Anoth~r ob~ect of the present invention is ~, to provide a method of cold forming which is cost effective~
20The~e and other ob~ects of the present invention will become more apparent during the course of the following detailed de~cription and appended claims.
The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.
IN THE DRAWINGS:
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Figure 1 is a perspective view partly in solid lines and partly in dotted linas of a starter gear with an integral pulse ring constructed in accordance with the method of the pre3ent invention:
S Figure 2 is a fragmentary sectional view of one-half of a circular piece of sheet ~etal which constitutes the starting material ~n practicing th~
principles of the present invention:
Figure 3 is a view similar to Figure 2 illu~trating a fir~t step in the process of thP
present invention wherein the circular piece of sheet metal is cold-formed into a can;
Figure 4 is a Yiew similar to Figurs 3 showing the next step in the method of th~ present lS invention including the formation of an annular section from the can;
Figure 5 i8 a view similar to Figure 4 showin~ the next step in the method of the present invention wherein a ~inal preform is cold-formed by thickening the annular section:
Figure 6 is a view similar to Figure 5 showing the teeth forming ~tep in the method of the present invention wherein the th~ckened annular sectio~ o~ the preform is cold-~ormed into a series of teeth;
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Figure 7 is a sectional view illuætrating the entire rotary holding unit and rotary tooth forming unit shown in Figure 6;
Figures 8, 9 and 10 are view8 similar to Figures 2-6 illustrating steps in performing another . embodiment of the method of the present invention;
:. Figures 11-13 ar~ views s~milar to Figures 8-10 illustrating steps in still another embodiment of the method of the present inYention; and Figures 14-17 are view si~ilar to Figures 2-6 illustxating steps in still another modificatiun of the ~ethod of the pr~sent invention.
' Re~rring now more particularly to Figures 1-7, there i~ shown therein a tootAed wheel in the : 15 form of a starter gear, generally indicated at 10, . constructed in accordance with the principles of the present invention. Figures 2-6 illustrate various steps in the method of making the starter gear 10 in accordance with one e~bodiment of the methcd of the ' 20 present invention. As shown, the starter gear 10 is :j made from a single circular pieca of sheet metal, as, for exampl~, steel capable of being cold-formed. As best shown in Figure 1, the starter ~ear 10 includes a central wall 12 of sheet metal having a thickness generally egual to the predetermined thickness o~ the sheet metal which forms the starting material. Figure j 2 illustrates in cross-section one-hal~ o~ a circular ,~ piecQ o~ sheet metal 14 tha ~ormation o~ which .
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2~336 constitutes a first step in the method of the present invention.
The starter gear 10 also includes an annular section formed integrally with the outer periphery o~
the central wall 12, a portion of which is cold-form2d into a serie~ of g~ar teeth 16 and a portion of which defines pul~e ring 18 in tha form of an axially extending cylindrical flange having a series oP
openings 20 extending radially therethrough at regular intervals. As shown, there are twelve openings 20 equally ~paced annularly sbout the axis o~ the starter gear 10 with each openin~ 20 being of ~enerally rectangular configuration.
Referring now more particularly to Figure 2, th~ circular piece of sheet metal 14 is illustrated therein to be a separate piece which may be ~tamped from a continuous sheet of steel. It will be : undersLood that the separation of the circular starting piece 14 from a roll or continuous web of 2 0 sheet material need not be accomplished in a ~ingle step wherein the circular piece 14 i8 produced for subsequent handling but may be only transitionally formed as a part of a multi-step sequenc~ in the ~ethod. For example, the circular piece 14 could be a transitional par~ in the step of cold-forming a can 22. Xowever, as shown in Figure 3, the circular piece of sheet metal 14 i~ placed over a circular support ~4 and a die 26 having a cylindrical opening 28 therein is moved axially so as to engage an outer annulus o~
the circul~r pieco 14 and &old-~ora the outer annulus 2~33~ ~
into a flange 30 extending axi~lly ~ro~ the outer periphery of ~ central wall 12 ~hereof.
Next, as shown in Figure 4, the can 22 i8 placed so that the central wall 12 i~ in abutment with a support ~2 having an annular reces~ 34 ~berein and a cantral plunger 36, which has an exterior cylindrical periphery 38 ~ized to engage within the axial flange 30 of th~ can 22, i5 moYed toward the support 3~ 80 as to form the central wall 12 of the lo can 22 with a central re~ess therein de~ined by an annular shoulder 400 A second outer annular plunger 42 is then moved toward the ~uppart 32 and tba plunger ~2 has an interior periphery 44 which is of notched cyl indrical conf iguration so as to engage both the 15 exterior surface and the end surface of the axial flange 30 of the can 22.
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.' During the movement o~ the outer annular plunger 42 toward the support 32, the portion o~ the axial flange 30 adjacent the central wall lZ is bulged 20 out so as to form two annular side-by-side wall port ions 4 6 and 4 8, one of which i8 integral at its inner periphery with the outer periphery o~ the center wall 12 and the other of which is integral at its inner periphery with the adjacent end of the remaining 25 portion of the axial flange 30. The outer periphery of both annular wall sections 46 and 48 are integrally interconnected as indicated at 50. ~t the end of .these procedures, the original circular piece of sheet metal 14 has now been cold-~ormed into a non-thickened 30 pre~orru which includes the center wall 12 having an outer annular section integral with the outer .
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periphery therao~, which ~ncludes the two side by-side annular wall portions 46 and 48 and the remaining :~
portion of the axial flange 30.
Referring now more particularly to Figure 5, the u~th~ckened preform is next ~ecured with a rotary holding un~t, generally indi~ated at 52, which includes a pair of complementary annular holding members 54 and 56. As ~hown in Figure 5, the complementa~y holding members 54 and 56 provide, when in operative holding relation, an inner pair of opposed central wall engaging surfaces 58 and 60, re~pectively, which are spaced axially apart a ; distance equal to the predetermined thickness of the central wall 12 so as to allow the central wall 12 to be engaged therebetween. As shown in Figure 5, the inner pair of opposed surfaces 58 and 60 extend - generally radially outwardly to an inner cylindrical plane, indicated by the phantom line ~1 in Figures 5 and 6, which is spaced inwardly from a pair of exterior peripheral ~ur~aces 6~ and 63 on the holding members 54 and 56 respectively. ~
- ,'', The complementary holding members 54 and 56 also have an outer pair of back-up sur~aces 6~ and 66, respectively, extending fro~ the inner pair of opposed . 25 central wall engaging surfa~es 58 and 60 respectively, to exterior peripheral surfaces 62 and 63, respectively. The peripheral surfaces 62 and 63 are coincident with a cylindrical trough plane concentric with the axis of the central wall 12 which defines the inner extent oP the troughs to be formed between the teeth on the preform. The outer extent of the ,~
11 ' ' .
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~ :' 2~g3~6 ~ surfaces 6~ and 66 extend generally radially to the ; peripheral ~urfaces 62 and 63 in the trough plane in axially ~paced relation. The axial ~pacing between the outer pair of surfaces 64 and 66 at the trough S plane ls a predetermined distance greater than the predeter~ined thickness of the central wall 14. It will also be noted that the surfaces 64 and 66 define a back-up space which is disposed within the annulus between the inner cylindrical plane 61 and the cylindrical trough plane.
In the operative sacured relation of the holding members 5~ and 56 with the non-thic~ene~
preform, the central wall 12 is emgaged between the inner pair of opposed surfaces 58 and 60 and the flange 30 i engaged within the back-up space defined by the surface 66. The non-thickened preform thus ~ecured in the rotary holding unit 52 is then cold-formed into a final thickened preform by moving a rotary thickening tool 68 radially inwardly into engagement with the connection 50 at the outer periphery o~ the annular wall portions ~6 and 48 of the non-thickened preform while the rotary holding unit 52 is rotated to thus cold-form the outer periphery of the annular section radially inwardly into a configuration wherein the integral connection 50 between the two annular wall portions 4~ and 4~ are ~hickened as well as the ad~acent portions of the annular wall portions themselves.
The next cold-forming step in the present method i8 to cold-form the series of teeth 16 in the thickened annular section of the final preform while la :' 2~3~
it is reta~ned in secured ralation with the rotary?
holding unit 52. Figure 7 illustrates that the rotary holding unit 52 forms a part of a cold-forming ~achine capable of cold-forming the series of teeth 16 in the annular ~ection of the pr~for~. The cold-for~ing of the series of teeth 16 is accompli~hed by a rotary?
tooth forming tool unit, generally indicated at 70~
having a tooth forming tool structure ~2 on the exterior periphery? thereof. The rotary tooth forming unit 70 forms a part of a machine which provides a means fsr effecting a rotational ~ovement of the rotary? holding unit 52 and the rotary? tooth ~orming :tool unit 70 in a predetermined rotational ..relationship wherein the axes are parallel and the .
rotational speeds are synchronized.
Any suitable motion-transmitting means may be provided in the machine for effecting the rotational relationship. For example, as s~own, the ' rotary? holding unit 52 has a tiTning belt pulley 74 :~ 20 fixed to rotate therewith and the rotary tooth forming tool unit 72 is likewise provided with a timing belt pulley 76 which rotates therewith. A timing belt 78 is trained about the two timing belt pulleys 74 and 76 and a pair of movable idler pulleys 80 in such a ~ay that the rotational relationship between the two ` ~ .rotary? units 52 and ? is maintained while permitting a relative movement between the two units and the axes thereo~ toward and away from one another. The tlming belt 78 is of a type which includes ti~ing teeth on ; 30 both the interior and exterior sur~aces thereo~. The teeth on the interior periphery, as shown, are trained . about the exterior periphery of the timing belt pulley ,.
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2~336 .
76 fixed with respect to the rotary holding unit 52 while the exterior teeth of the timing belt 78 are trained about the timing belt pulley 76 f~xed to the rotary tooth forming tool unit 70. The two idler pulleys 80, which are on opposite sides of a plane pa~ing through the axes of rotation of the two units, are movable to take up any belt configuration change as a result of the relative ~ove~ent o~ the two units toward and away from one another with the movement of the idlers 80 being commensurate so as to maintain the synchronous rotational movement.
In this regard, it will be noted that the directions of rota~ion of the rotary units 52 and 70 are in opposite directions s~ that the tooth forming periphery 72 o~ the rotary tool unit 70 can be mo~ed into meshing relation with the periphery of the annular section of the preform secured to the rotary holding unit 52. It will aliso be noted that the thickness of the annular section is greater than the predetermined sheet metal thickness and no greater than the predeter~ined distance between surfaces 64 and 66. More specifically, as shown, the thickness of the annular section is slightly greater than twice the predetermined thi.ckness of the sheet metal but less than the predetermined distance between the tooth side forming surfaces 64 and 66.
once the predeter~ined rotational relationship has been established, the two rotary units 52 and 70 will b~ rotated in the prede~ermined rotational relationship which, for example, is an ldentical speed in opposite directions of 150-180 ~ .
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revolutions per ~inute. with the two rotary units 52 and 70 in the position ~hown in Figur~ 7 and while the rotational relationship i8 retainsd, a relative movement between the two rotary units and their parallel vert.i.cal axes m a direction towards one ano~her is effected. Preferably, th~ rotary tool unit 70 is moved while the axis of rotation of the rotary holding unit 52 i~ held stationary: although both unit~ could be moved or only the rotary unit 52 could be moved.
An exemplary feed rate o~ the ~ovement of t~e axis of the rotary tool unit 70 toward the axi~ of the rotary holding unit 52 is approximately 120 mm. per minute.
As the outer tool forming periphery 7~ of the ~ool forming tool unit 70 ~o~es to engage the periphery o~
the ~nnular section of the preform in cooperating metal deforming relation inwardly of the exterior periphery thereof, the sheet metal of the annular section is cold-for~ed into a series of teeth.
Preferably, this is accomplished by effecting a movement o~ the rotary tool unit 70 toward the holder unit to an extent which equals about four meshing turns. When this feed movement has been reached, the drive fox the two units is reversed and then the ~eed ,movement is advanced until ~our more meshing turns are ; 25 acco~plished. These alternative direction feeds are repeated until the full tooth configuration has been completed.
Thus, during the i~feed, the peripher~es of the series of teeth 16 are cold-formed by rolling contact with the tooth ~orming periphery 72 o~ the tooth ~or~ing tool unit 70. ~he tooth forming periphery 72 consists of teeth-like projections with ' ~ '' ~
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2 ~ 3 ~ ~
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trough-like spaces therebetween. The trough-like spaces form the teeth on the preform and the teeth-like projections form the troughs between the teeth on the preform. Ths tips of t~e teeth-like projectionE
form the bottom of the troughs. It is noted that the width of the teeth-like projections is greater than the width of the teeth which are formed on the preform. During the formation of the teeth on the preform, the preform material which is initially lo disposed in the spaces where the troughs are finally provided i6 moved by the teeth-like projections of the tooth forming periphery 72 either radially inwardly into the back-up space or axially outwardly. Because of ~he qreater width of the teeth-like pro~ections, the axial movement must be accompanied by movements in opposite circumferential directions. This circum~erential movement results in a build-up of material on both sides of the teeth being formed on the preform. This build-up of the sides of tha teeth is allowed to take place on a free-~orming basis in the preferred configuration of the tooth-forming periphery 72 wherein the teeth-like projections are of uniform ~ross-sectional configuration across their entire width. In this pre~erred configuration, there are no spaced tooth-side defining flanges such as provided in some of the tooth-forming peripheral configuration in the '399 application. With the preferred configuration, the entire sides of the teeth of the preform are ~ree formed. It i~ within the contemplation of the present invention to provide ~langes on the tooth-forming periphery 72 at the posi~ions where it ls desired to ha~e the sides of the teeth end so long as the flanges are slotted or .
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208~33~
otherwise relieved 50 as to insure that at least portion~ o~ the sides of the taeth ar~ free formed.
Tha amount of relief provided should be sufficient to overcome the problem of premature breakage of the teeth-like pro~ections of ~he tooth-forming periphery heretofore experienced as a~oresaid.
In the preferred embodiment ~hown where the flanges ar~ effectively slotted with a cross-se~tional configuration the same as the trough-l~ke depressions of the tooth-forming periphery 72, the desir~d width of the teeth formed on the pre~orm generally conforms to axially ~paced planes passing through the juncture between the peripheral surfa es 62 and 63 with the outer pair of ~urfaces 64 and 66. Figure 6 shows the position of the tooth-forminq periphery 72 with respect to the preform at the end of the relative movement of ~h~ unit~ toward one another. It will be noted that the tip o~ the tooth-like projections extend to the trough plane o~ the ~ormed teeth and that opposite end portions of the tips are substantially in engagement with the exterior peripheral sur~aces 62 and 63. It will also be noted that the back-up space is filled with preform material. In this regard, it will be noted that the portion of surface 66 which extends axially in the plane 61 l~mits the amount of radially inwardly movement of preform material which can occur during the ~ormation of the teeth. Preferably, the limitation is cnough to fill the entire back-up space in the areas of the formed teeth as well as the ~ormed trough shown in the cross~section o~ Figura 6. In its broadest aspeats, the invention contemplates that some ' ' ~. ~::: ~ ::: ~ '' :;'; ~ : ;, ~ ~-,, i, ~ ", " - ,, ::,",,~,, " " ,,, ~"~ ", ;, 2~33~
~oid are~s, as, for example, where the teeth are, can exist within the back-up space a~ter tooth ~ormation.
With the preferred embodiment as shown in Figure 6, the ~illing of the back-up space results in the Pree-forming of the sides of the teeth beyond the desiredwidth of the aforesaid two plane~.
It is great~y preferred that the annular : section of the preform have an outer peripheral :dimension which is at least as great as the orest dimension of the series of teeth and does not exceed this dimen ion by more than approximat~ly 7% or fun~tionally an amount which would enable a meshing relationship between the annular section of the prefor~ and the perophery oP the tooth ~or~ing tool unit when initial engagement occurs. This size relationship insures that it is not necessary to cause cold flow in a radially outward direction but rather than the direction of cold ~low of metal ic either ;axially outwardly or radially inwardly or a combination of both. It will be understaood however that, in its broadest aspects, the method does comprehend cold flow radially outwardly.
In its broadest aspects, the present invention contemplates having the ~ides free-formed, . 25 however, preferably, the~ method of the present invention contemplates machining one or both o~ the sides of the teeth so that the sides are coincident with the desired spaced planes. In the embodiment thus far described, only the ~ree~ormed side in alignment with surface 64 ~ machined and the other is left free-formed with the flange 30 extending ``
l 18 .
,~1 . .
:1 .
., ' ' ' ' ~
2~8833~
outwardly thereof. Thi~ rel~tionship is evident from the perspective view of the completed toothed wheel 10 shown in Fi~ure 1.
As best shown in Figure 1, the central wall 12 is centrally apertured, as indicated ~t 82, which i8 a cold-forming step that ~ay be accomplished after the series of teeth 16 are cold-formed or preferably this opening i~ ~ormed prior there~o. Another cold-forming step which is made after the ~eries of teeth 16 have been cold-formed is ~he stamping o~ the series of openings 20 of rectangular configuration at regular intervals along ~he remaining portion of the axial flange 30. The exterior surface o~ the remaining - portion of the axial Plange 30 is pre~erably machined in a lathe to ~orm the pulse ring 18 with an accurate -; cylindrical exterior surface ~hich intersects with the openings 20 to accurately provide signals at regular intervals which are used to provide computer control for the engine.
: ; , In the case o~ the starter gear 10 made in accordance with the above procedure, it is desirable that the f~nal configuration be given a heat treatment at least in the area of the series of teeth 16.
Pre~erably, the heat treatment is by induction ~eating ~' 25 to a temperature of 850 to 900-C followed by quenching ~ in water to room temperature. Heat treatment is ;i considered desirable in the case of a starting gear because o~ the severe loads which are imposed along the volute surfaces of the teeth in operation. With the pre~ent invention, the teeth can be made to be ~ubstantially solid i~ the aentral area where th~ load i8 supplied by providing enough material in the ' .
19 .
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psrform to ~nsure that the back-up space is ~illed.
However, as previously ~ndicated in its broader aspects, the back-up space can have void areas. In ~orminq other toothed wheels, such as timing belt pulleys and pulse rings, the prov~sion of an integral pulse ring with the series of teeth may be eliminated and the heat treatments can likewise be eliminated.
Figures 8-10 illustrate additional method step variations which are within the contemplation of the present invention. Figure 8 illustrates a circular piece of sheet metal 114 of predetermined thickness whioh is secured in a rotary holding unit 152 o~ modified form including first and ~econd annular holding members ~54 and 156. As sh~wn, the 15holding mambers 154 and 156 are formed with an inner pair of oppositely facing central wall engaging surfaces 158 and 160 which are adapted to engage the central wall 112 when in operative holding relation therewith. A~ be~ore, the inner pair o~ 6urfaces 158 ; 20 and 160 extend outwardly to an inner cylindriaal plane 161 which is inwardly of the trough plane of the finished toothed wheel. As before, the holding members 154 and 156 include outwardly facing exterior peripheral surfaces 162 and 163, respectively, which are disposed within the trough plane. An outer pair of surface 164 and 166 respectively extend from the surfaces 158 and 160 in plane 161 to the surfaces 162 and 163, respectively, so as to define a back-up 6pace between the plane 161 and the trough plane.
30The holding members 154 and 156 in operative holding relation cooperate with a rotary preform ' '~
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rolling member 168 having a U-shaped groov~ 169 formed in it~ outer periphery. By advancing the rotary preform rolling member 168 with respect to the rotary holding unit 152 in a manner similar to the rotary member 68 previously described, an outer annulus of the circular piece 114 extending radlally outwardly ; beyond the surface 162 i~ cold-for~ed into a peripheral flange extending outwardly and then downwardly from a curved control port;on so as to provide a cross sectional configuration which opens generally radially inwardly. While Pinal configuration o~ the annular section which is cold-formed by the preform rolling member 168 could be of inverted se~i-circular shape, the configuration is more of an inverted U-shape having a pair o~ side-by-side annular wall portions 146 and 148 integrally interconnected by a central arcuate transitional wall portion 150.
It will be understood that the annular section provided by wall portions 146, 148, and 150 could be thickened by utilizing a thickening tool , similar to the tool 68; however, in th~ method ~ according to 8-lO, the next step is to cold-form the ', annular section into a series of teeth. This is accomplished by a rotary tooth ~orming tool unit 170 which is constructed and operated like the rotary tooth forming tool unit 70 to include a tooth forming periphery 172. The tool unit 170 is operated in the same manner as indicated before with at least portions of the sides of the teeth being free formed and the back-up space preferably Pilled with steel material, ~, a8 i8 shown in Figure 10. The finished toothed wheel ~1 ' , .. . . .. .
,. ~ , . . . .
This invention relates to toothed wheels of the type utilized in motor vehicles as, for example, in the starter assembly thereof and more particularly to improvements in the method of making such toothed wheels.
In my prior United States Patent No. 5,152~061, there is disclosed a method of forming a ~oothed wheel including a series of cold-formed peripheral teeth having sides spaced apart a predetermined distance utilizing (1) a rotary holding unit having structure providing a generally radially outwardly facing control surface and (2) a rotary tooth-forming tool unit having a rotational axis and a tooth-forrning periphery extending annularly about the rotational axis. One of the rota~y units includes two annular flanges extending outwardly thereof baving two smooth tooth-side forming surfaces facing toward one another spaced apart the predetermined distance. The method of the '061 patent comprises the initial step of cold-forming a circular piece of sheet metal of predetermined thickness into a preform having an outer annular section of generally uniform cross-sectional configuration and an . ~.
, ~ integral sheet metal central wall generally of the predetermined thickness extending annularly inwardly from the outer annular section toward a pre~orm axis, the outer ;
annular section having (l) a width greater than the ' .
~ .
2~8~33~
predetermined thickness but no greater than the predeterminad distance, and (2) a~ outer periphery which will allow a ~eshing action with the tooth-formin~ periphery of the tooth-forming tool unit. The method of the '061 patent also includes the step of rotatin~ (1) the rotary holding unit with the preform secured thereto about the preform axi~ and : with the control surface underlying at least a portion 10 of the annular section and (2) the tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and the rotational speeds are synchroni~ed.
While the rotary holding unit with th~ preform secured thereko and the tooth-forming tool unit are in the predetermined rotational relation, the method of the '061 patent further includes the ~tep of affecting a relative movement between the units and the axes thereof in a direction toward one another to engage the tooth-formirlq periphery of the tooth-: forming tool unit in cooperating metal-deforming relation with the annular section inwardly of the exterior periphery thereof until the sheet metal of the annular section is cold-formed into the series of teeth, the peripheries of which are cold-formed by rolling contac~ with the tooth-forming periphery of , . the tooth-forming ~ool unit and portions of the sides of which are smooth and cold-formed by contact with the smoo~h too~h-side forming sur~ace so that an amount of sheet metal which would otherwise uncontrollably flow axially outwardly of the ~mooth tooth-side ~orming sur~ace~ i~ conaentrated within the teeth and/or the radially inward back-up thare~or.
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20~3~
It has been found that, while the total confinement o the metal during the cold-forming operatlon has the advantages stated, there also existed a tendency to break teeth off of the rotary tooth-forming tool unit after a period of operation which, on occasion, would be substantially less than the normal ~xpected operative life of the tool unit.
The frequency of tooth failure was considered unexpected particularly in the tool construction where tha two annular flanges for forming the two ~mooth tooth sides were integrally interconnected on opposite side~ of the ~orming teeth.
An object of the present invention is to overcome the problem of frequency of tooth failure in the ro~ary tooth ~orming.unit of the above described method of the '061 patent. In accordance with the principles of the present invention this objective is achieved by providing a method of ~orming a one-piece sheet metal toothed wheel includin~ a central sheat metal wali of predetermined thickness and a series of cold-~ormed inteqral teeth on the periphery of the central wall defined by troughs extending radially inwardly therebetween to a cylindrical trough plane concentric with an axis of the central wall, the series o~ cold~formed integral teeth having an op~rative width de~ined by spaced tooth side defining planes. The method utilizes ~1) a rotary holding unit which in holding operation provides an inner pair of opposed central wall-engaging surfaces extending generally radially outwardly to a cylindrical inner plane ~paced inwardly ~rom an outer cylindrical plane of a size equal to the trough plane and an outer pair -- - ., .. .. . . ... .. .. - . ..... . .. . . .... . ... . ..
.:.. - , .: .. ,: :,. , .:,, . : .:: .:.. . . ..... :. :.: . , . ~ :. : ,. :
~0~3~ :
of back-up suraces extending from the inner pair of opposed central wall-engaging surfaces at the inner : plan~ to the outer plane where the outer pair of ~urfaces are spaced apart a predetermined distance which i~ greater than the spacing between the inner palr of aurfaces so as to define a back~up sp~ce within an annulus between the inner and outer planes a~d (2) a rotary tooth-formin~ tool unit having a rotational axis and a tooth-forming periphery ~o extending annularly about the rotational axi~. The method c~mprises a combin~tion of steps the initial one o~ which is cold-forming a circular piece of sheet metal into a preform having an outer annular section of generally uniform cross-sectional coniguration and an integral sheet metal central wall qenerally of the predetermined thickness extending generally radially inwardly from tha outer annular section toward a prerorm axis. The outer annular section has (l) a width greater than the predetermined thickness but no greater than the predetermined distance, and (2) an outer periphery extending beyond the trough plane which will allow a meshing action with the tooth-forming periphery o~ the tooth-forming tool unit. The next step is rotating (1) the rotary holding unit with the prefor~ secured thereto about the preform axis and an inner portion of the outer annular section within the back-up space and an outer portion of the outer annular section extending radially outwardly o~ the back-up space, and (2) the tooth-forming tool unit 30 . about the rotational axis thereof in a predetermined rotational relation wherein the axes are parallel and the rotational ~peeds are synchronized. ~he third step is per~ormed while th; rotary holding unit with .
.
~ ' 2~S~33~
the preform secured thereto and the tooth-forming tool unit are in the predetermined rotational relation affecting a relative movement between the uniti and the axes thereof in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperating metal-deforning relation with the outer portion of the outer annular section inwardly of the exterior periphery thereo~
until the sheet metal o~ the outer portion of the ainnular section is cold formed into the series of teeth and displaced ~rom the troughs therebetween so that after the series of teeth are cold-formed the toothed wheel includes a back-up portion having - surfaces conforming to an outer extent of each o~ the outer pair of ~iur~ace defining the back-up space, the peripheries of the series of teeth being cold-formed by rolling contact with the tooth-forming periphery of the tooth-forming tool unit and the sides of the series of teeth ihcluding portions disposed.outwardly beyond the spaced tooth side defining planes being j free formed without surface contact by the axial~y outward movement of the metal defining the outer porti~n of the outer annular section.
.. . .
Prefera~ly, the rotary holding tool unit further provides a pair of cylindrical extarior peripheral sur~aces extending axially in opposite directions from the outer pair of surfaces within the outer plane and the tooth formin~ periphery of the tooth ~orming tool unit includes trough forming teeth-like projections having exterior tips which extend toæaid trough plane. Pre~erably, in the third step, at th~ end of the relative movement between the units 208~3~
, . . .
~owards one another to engaqe the tooth forming periphery of the ~oo~h forming tool unit in cooperating relation with the outer portion of the outer annular section, the tips substantially engage the exterior periphery sur~aces of the rotary holding unit.
Preferably, the spaced tooth side def~ning planes pas~ generally through the outer pair of surfaces spaced apart within ths outer plane.
Preferably, the method includes a ~ourth step which is the machinlng of the free-formed portions of the sides of the series o~ teeth at least along one common side so that the machined ~ides of the teeth on the one common ~ide are disposed in a co~mon plane constituting one of the spaced tooth si~e dePining planes.
Anoth~r ob~ect of the present invention is ~, to provide a method of cold forming which is cost effective~
20The~e and other ob~ects of the present invention will become more apparent during the course of the following detailed de~cription and appended claims.
The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.
IN THE DRAWINGS:
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Figure 1 is a perspective view partly in solid lines and partly in dotted linas of a starter gear with an integral pulse ring constructed in accordance with the method of the pre3ent invention:
S Figure 2 is a fragmentary sectional view of one-half of a circular piece of sheet ~etal which constitutes the starting material ~n practicing th~
principles of the present invention:
Figure 3 is a view similar to Figure 2 illu~trating a fir~t step in the process of thP
present invention wherein the circular piece of sheet metal is cold-formed into a can;
Figure 4 is a Yiew similar to Figurs 3 showing the next step in the method of th~ present lS invention including the formation of an annular section from the can;
Figure 5 i8 a view similar to Figure 4 showin~ the next step in the method of the present invention wherein a ~inal preform is cold-formed by thickening the annular section:
Figure 6 is a view similar to Figure 5 showing the teeth forming ~tep in the method of the present invention wherein the th~ckened annular sectio~ o~ the preform is cold-~ormed into a series of teeth;
~a~3~
Figure 7 is a sectional view illuætrating the entire rotary holding unit and rotary tooth forming unit shown in Figure 6;
Figures 8, 9 and 10 are view8 similar to Figures 2-6 illustrating steps in performing another . embodiment of the method of the present invention;
:. Figures 11-13 ar~ views s~milar to Figures 8-10 illustrating steps in still another embodiment of the method of the present inYention; and Figures 14-17 are view si~ilar to Figures 2-6 illustxating steps in still another modificatiun of the ~ethod of the pr~sent invention.
' Re~rring now more particularly to Figures 1-7, there i~ shown therein a tootAed wheel in the : 15 form of a starter gear, generally indicated at 10, . constructed in accordance with the principles of the present invention. Figures 2-6 illustrate various steps in the method of making the starter gear 10 in accordance with one e~bodiment of the methcd of the ' 20 present invention. As shown, the starter gear 10 is :j made from a single circular pieca of sheet metal, as, for exampl~, steel capable of being cold-formed. As best shown in Figure 1, the starter ~ear 10 includes a central wall 12 of sheet metal having a thickness generally egual to the predetermined thickness o~ the sheet metal which forms the starting material. Figure j 2 illustrates in cross-section one-hal~ o~ a circular ,~ piecQ o~ sheet metal 14 tha ~ormation o~ which .
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2~336 constitutes a first step in the method of the present invention.
The starter gear 10 also includes an annular section formed integrally with the outer periphery o~
the central wall 12, a portion of which is cold-form2d into a serie~ of g~ar teeth 16 and a portion of which defines pul~e ring 18 in tha form of an axially extending cylindrical flange having a series oP
openings 20 extending radially therethrough at regular intervals. As shown, there are twelve openings 20 equally ~paced annularly sbout the axis o~ the starter gear 10 with each openin~ 20 being of ~enerally rectangular configuration.
Referring now more particularly to Figure 2, th~ circular piece of sheet metal 14 is illustrated therein to be a separate piece which may be ~tamped from a continuous sheet of steel. It will be : undersLood that the separation of the circular starting piece 14 from a roll or continuous web of 2 0 sheet material need not be accomplished in a ~ingle step wherein the circular piece 14 i8 produced for subsequent handling but may be only transitionally formed as a part of a multi-step sequenc~ in the ~ethod. For example, the circular piece 14 could be a transitional par~ in the step of cold-forming a can 22. Xowever, as shown in Figure 3, the circular piece of sheet metal 14 i~ placed over a circular support ~4 and a die 26 having a cylindrical opening 28 therein is moved axially so as to engage an outer annulus o~
the circul~r pieco 14 and &old-~ora the outer annulus 2~33~ ~
into a flange 30 extending axi~lly ~ro~ the outer periphery of ~ central wall 12 ~hereof.
Next, as shown in Figure 4, the can 22 i8 placed so that the central wall 12 i~ in abutment with a support ~2 having an annular reces~ 34 ~berein and a cantral plunger 36, which has an exterior cylindrical periphery 38 ~ized to engage within the axial flange 30 of th~ can 22, i5 moYed toward the support 3~ 80 as to form the central wall 12 of the lo can 22 with a central re~ess therein de~ined by an annular shoulder 400 A second outer annular plunger 42 is then moved toward the ~uppart 32 and tba plunger ~2 has an interior periphery 44 which is of notched cyl indrical conf iguration so as to engage both the 15 exterior surface and the end surface of the axial flange 30 of the can 22.
. ~ .
.' During the movement o~ the outer annular plunger 42 toward the support 32, the portion o~ the axial flange 30 adjacent the central wall lZ is bulged 20 out so as to form two annular side-by-side wall port ions 4 6 and 4 8, one of which i8 integral at its inner periphery with the outer periphery o~ the center wall 12 and the other of which is integral at its inner periphery with the adjacent end of the remaining 25 portion of the axial flange 30. The outer periphery of both annular wall sections 46 and 48 are integrally interconnected as indicated at 50. ~t the end of .these procedures, the original circular piece of sheet metal 14 has now been cold-~ormed into a non-thickened 30 pre~orru which includes the center wall 12 having an outer annular section integral with the outer .
- . . .. - , . .
- , , ... " . ~ .. . . .
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periphery therao~, which ~ncludes the two side by-side annular wall portions 46 and 48 and the remaining :~
portion of the axial flange 30.
Referring now more particularly to Figure 5, the u~th~ckened preform is next ~ecured with a rotary holding un~t, generally indi~ated at 52, which includes a pair of complementary annular holding members 54 and 56. As ~hown in Figure 5, the complementa~y holding members 54 and 56 provide, when in operative holding relation, an inner pair of opposed central wall engaging surfaces 58 and 60, re~pectively, which are spaced axially apart a ; distance equal to the predetermined thickness of the central wall 12 so as to allow the central wall 12 to be engaged therebetween. As shown in Figure 5, the inner pair of opposed surfaces 58 and 60 extend - generally radially outwardly to an inner cylindrical plane, indicated by the phantom line ~1 in Figures 5 and 6, which is spaced inwardly from a pair of exterior peripheral ~ur~aces 6~ and 63 on the holding members 54 and 56 respectively. ~
- ,'', The complementary holding members 54 and 56 also have an outer pair of back-up sur~aces 6~ and 66, respectively, extending fro~ the inner pair of opposed . 25 central wall engaging surfa~es 58 and 60 respectively, to exterior peripheral surfaces 62 and 63, respectively. The peripheral surfaces 62 and 63 are coincident with a cylindrical trough plane concentric with the axis of the central wall 12 which defines the inner extent oP the troughs to be formed between the teeth on the preform. The outer extent of the ,~
11 ' ' .
.~:
, :
''.
~ :' 2~g3~6 ~ surfaces 6~ and 66 extend generally radially to the ; peripheral ~urfaces 62 and 63 in the trough plane in axially ~paced relation. The axial ~pacing between the outer pair of surfaces 64 and 66 at the trough S plane ls a predetermined distance greater than the predeter~ined thickness of the central wall 14. It will also be noted that the surfaces 64 and 66 define a back-up space which is disposed within the annulus between the inner cylindrical plane 61 and the cylindrical trough plane.
In the operative sacured relation of the holding members 5~ and 56 with the non-thic~ene~
preform, the central wall 12 is emgaged between the inner pair of opposed surfaces 58 and 60 and the flange 30 i engaged within the back-up space defined by the surface 66. The non-thickened preform thus ~ecured in the rotary holding unit 52 is then cold-formed into a final thickened preform by moving a rotary thickening tool 68 radially inwardly into engagement with the connection 50 at the outer periphery o~ the annular wall portions ~6 and 48 of the non-thickened preform while the rotary holding unit 52 is rotated to thus cold-form the outer periphery of the annular section radially inwardly into a configuration wherein the integral connection 50 between the two annular wall portions 4~ and 4~ are ~hickened as well as the ad~acent portions of the annular wall portions themselves.
The next cold-forming step in the present method i8 to cold-form the series of teeth 16 in the thickened annular section of the final preform while la :' 2~3~
it is reta~ned in secured ralation with the rotary?
holding unit 52. Figure 7 illustrates that the rotary holding unit 52 forms a part of a cold-forming ~achine capable of cold-forming the series of teeth 16 in the annular ~ection of the pr~for~. The cold-for~ing of the series of teeth 16 is accompli~hed by a rotary?
tooth forming tool unit, generally indicated at 70~
having a tooth forming tool structure ~2 on the exterior periphery? thereof. The rotary tooth forming unit 70 forms a part of a machine which provides a means fsr effecting a rotational ~ovement of the rotary? holding unit 52 and the rotary? tooth ~orming :tool unit 70 in a predetermined rotational ..relationship wherein the axes are parallel and the .
rotational speeds are synchronized.
Any suitable motion-transmitting means may be provided in the machine for effecting the rotational relationship. For example, as s~own, the ' rotary? holding unit 52 has a tiTning belt pulley 74 :~ 20 fixed to rotate therewith and the rotary tooth forming tool unit 72 is likewise provided with a timing belt pulley 76 which rotates therewith. A timing belt 78 is trained about the two timing belt pulleys 74 and 76 and a pair of movable idler pulleys 80 in such a ~ay that the rotational relationship between the two ` ~ .rotary? units 52 and ? is maintained while permitting a relative movement between the two units and the axes thereo~ toward and away from one another. The tlming belt 78 is of a type which includes ti~ing teeth on ; 30 both the interior and exterior sur~aces thereo~. The teeth on the interior periphery, as shown, are trained . about the exterior periphery of the timing belt pulley ,.
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2~336 .
76 fixed with respect to the rotary holding unit 52 while the exterior teeth of the timing belt 78 are trained about the timing belt pulley 76 f~xed to the rotary tooth forming tool unit 70. The two idler pulleys 80, which are on opposite sides of a plane pa~ing through the axes of rotation of the two units, are movable to take up any belt configuration change as a result of the relative ~ove~ent o~ the two units toward and away from one another with the movement of the idlers 80 being commensurate so as to maintain the synchronous rotational movement.
In this regard, it will be noted that the directions of rota~ion of the rotary units 52 and 70 are in opposite directions s~ that the tooth forming periphery 72 o~ the rotary tool unit 70 can be mo~ed into meshing relation with the periphery of the annular section of the preform secured to the rotary holding unit 52. It will aliso be noted that the thickness of the annular section is greater than the predetermined sheet metal thickness and no greater than the predeter~ined distance between surfaces 64 and 66. More specifically, as shown, the thickness of the annular section is slightly greater than twice the predetermined thi.ckness of the sheet metal but less than the predetermined distance between the tooth side forming surfaces 64 and 66.
once the predeter~ined rotational relationship has been established, the two rotary units 52 and 70 will b~ rotated in the prede~ermined rotational relationship which, for example, is an ldentical speed in opposite directions of 150-180 ~ .
2~8g33G
revolutions per ~inute. with the two rotary units 52 and 70 in the position ~hown in Figur~ 7 and while the rotational relationship i8 retainsd, a relative movement between the two rotary units and their parallel vert.i.cal axes m a direction towards one ano~her is effected. Preferably, th~ rotary tool unit 70 is moved while the axis of rotation of the rotary holding unit 52 i~ held stationary: although both unit~ could be moved or only the rotary unit 52 could be moved.
An exemplary feed rate o~ the ~ovement of t~e axis of the rotary tool unit 70 toward the axi~ of the rotary holding unit 52 is approximately 120 mm. per minute.
As the outer tool forming periphery 7~ of the ~ool forming tool unit 70 ~o~es to engage the periphery o~
the ~nnular section of the preform in cooperating metal deforming relation inwardly of the exterior periphery thereof, the sheet metal of the annular section is cold-for~ed into a series of teeth.
Preferably, this is accomplished by effecting a movement o~ the rotary tool unit 70 toward the holder unit to an extent which equals about four meshing turns. When this feed movement has been reached, the drive fox the two units is reversed and then the ~eed ,movement is advanced until ~our more meshing turns are ; 25 acco~plished. These alternative direction feeds are repeated until the full tooth configuration has been completed.
Thus, during the i~feed, the peripher~es of the series of teeth 16 are cold-formed by rolling contact with the tooth ~orming periphery 72 o~ the tooth ~or~ing tool unit 70. ~he tooth forming periphery 72 consists of teeth-like projections with ' ~ '' ~
~, .
- ,: . . . . ... , :, ,: : .. ,; . . :", .~ ,, . , ; .
2 ~ 3 ~ ~
,, .
trough-like spaces therebetween. The trough-like spaces form the teeth on the preform and the teeth-like projections form the troughs between the teeth on the preform. Ths tips of t~e teeth-like projectionE
form the bottom of the troughs. It is noted that the width of the teeth-like projections is greater than the width of the teeth which are formed on the preform. During the formation of the teeth on the preform, the preform material which is initially lo disposed in the spaces where the troughs are finally provided i6 moved by the teeth-like projections of the tooth forming periphery 72 either radially inwardly into the back-up space or axially outwardly. Because of ~he qreater width of the teeth-like pro~ections, the axial movement must be accompanied by movements in opposite circumferential directions. This circum~erential movement results in a build-up of material on both sides of the teeth being formed on the preform. This build-up of the sides of tha teeth is allowed to take place on a free-~orming basis in the preferred configuration of the tooth-forming periphery 72 wherein the teeth-like projections are of uniform ~ross-sectional configuration across their entire width. In this pre~erred configuration, there are no spaced tooth-side defining flanges such as provided in some of the tooth-forming peripheral configuration in the '399 application. With the preferred configuration, the entire sides of the teeth of the preform are ~ree formed. It i~ within the contemplation of the present invention to provide ~langes on the tooth-forming periphery 72 at the posi~ions where it ls desired to ha~e the sides of the teeth end so long as the flanges are slotted or .
. ., , . . , ~`. . . . . . . .
208~33~
otherwise relieved 50 as to insure that at least portion~ o~ the sides of the taeth ar~ free formed.
Tha amount of relief provided should be sufficient to overcome the problem of premature breakage of the teeth-like pro~ections of ~he tooth-forming periphery heretofore experienced as a~oresaid.
In the preferred embodiment ~hown where the flanges ar~ effectively slotted with a cross-se~tional configuration the same as the trough-l~ke depressions of the tooth-forming periphery 72, the desir~d width of the teeth formed on the pre~orm generally conforms to axially ~paced planes passing through the juncture between the peripheral surfa es 62 and 63 with the outer pair of ~urfaces 64 and 66. Figure 6 shows the position of the tooth-forminq periphery 72 with respect to the preform at the end of the relative movement of ~h~ unit~ toward one another. It will be noted that the tip o~ the tooth-like projections extend to the trough plane o~ the ~ormed teeth and that opposite end portions of the tips are substantially in engagement with the exterior peripheral sur~aces 62 and 63. It will also be noted that the back-up space is filled with preform material. In this regard, it will be noted that the portion of surface 66 which extends axially in the plane 61 l~mits the amount of radially inwardly movement of preform material which can occur during the ~ormation of the teeth. Preferably, the limitation is cnough to fill the entire back-up space in the areas of the formed teeth as well as the ~ormed trough shown in the cross~section o~ Figura 6. In its broadest aspeats, the invention contemplates that some ' ' ~. ~::: ~ ::: ~ '' :;'; ~ : ;, ~ ~-,, i, ~ ", " - ,, ::,",,~,, " " ,,, ~"~ ", ;, 2~33~
~oid are~s, as, for example, where the teeth are, can exist within the back-up space a~ter tooth ~ormation.
With the preferred embodiment as shown in Figure 6, the ~illing of the back-up space results in the Pree-forming of the sides of the teeth beyond the desiredwidth of the aforesaid two plane~.
It is great~y preferred that the annular : section of the preform have an outer peripheral :dimension which is at least as great as the orest dimension of the series of teeth and does not exceed this dimen ion by more than approximat~ly 7% or fun~tionally an amount which would enable a meshing relationship between the annular section of the prefor~ and the perophery oP the tooth ~or~ing tool unit when initial engagement occurs. This size relationship insures that it is not necessary to cause cold flow in a radially outward direction but rather than the direction of cold ~low of metal ic either ;axially outwardly or radially inwardly or a combination of both. It will be understaood however that, in its broadest aspects, the method does comprehend cold flow radially outwardly.
In its broadest aspects, the present invention contemplates having the ~ides free-formed, . 25 however, preferably, the~ method of the present invention contemplates machining one or both o~ the sides of the teeth so that the sides are coincident with the desired spaced planes. In the embodiment thus far described, only the ~ree~ormed side in alignment with surface 64 ~ machined and the other is left free-formed with the flange 30 extending ``
l 18 .
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outwardly thereof. Thi~ rel~tionship is evident from the perspective view of the completed toothed wheel 10 shown in Fi~ure 1.
As best shown in Figure 1, the central wall 12 is centrally apertured, as indicated ~t 82, which i8 a cold-forming step that ~ay be accomplished after the series of teeth 16 are cold-formed or preferably this opening i~ ~ormed prior there~o. Another cold-forming step which is made after the ~eries of teeth 16 have been cold-formed is ~he stamping o~ the series of openings 20 of rectangular configuration at regular intervals along ~he remaining portion of the axial flange 30. The exterior surface o~ the remaining - portion of the axial Plange 30 is pre~erably machined in a lathe to ~orm the pulse ring 18 with an accurate -; cylindrical exterior surface ~hich intersects with the openings 20 to accurately provide signals at regular intervals which are used to provide computer control for the engine.
: ; , In the case o~ the starter gear 10 made in accordance with the above procedure, it is desirable that the f~nal configuration be given a heat treatment at least in the area of the series of teeth 16.
Pre~erably, the heat treatment is by induction ~eating ~' 25 to a temperature of 850 to 900-C followed by quenching ~ in water to room temperature. Heat treatment is ;i considered desirable in the case of a starting gear because o~ the severe loads which are imposed along the volute surfaces of the teeth in operation. With the pre~ent invention, the teeth can be made to be ~ubstantially solid i~ the aentral area where th~ load i8 supplied by providing enough material in the ' .
19 .
. . ... :
2~3~
psrform to ~nsure that the back-up space is ~illed.
However, as previously ~ndicated in its broader aspects, the back-up space can have void areas. In ~orminq other toothed wheels, such as timing belt pulleys and pulse rings, the prov~sion of an integral pulse ring with the series of teeth may be eliminated and the heat treatments can likewise be eliminated.
Figures 8-10 illustrate additional method step variations which are within the contemplation of the present invention. Figure 8 illustrates a circular piece of sheet metal 114 of predetermined thickness whioh is secured in a rotary holding unit 152 o~ modified form including first and ~econd annular holding members ~54 and 156. As sh~wn, the 15holding mambers 154 and 156 are formed with an inner pair of oppositely facing central wall engaging surfaces 158 and 160 which are adapted to engage the central wall 112 when in operative holding relation therewith. A~ be~ore, the inner pair o~ 6urfaces 158 ; 20 and 160 extend outwardly to an inner cylindriaal plane 161 which is inwardly of the trough plane of the finished toothed wheel. As before, the holding members 154 and 156 include outwardly facing exterior peripheral surfaces 162 and 163, respectively, which are disposed within the trough plane. An outer pair of surface 164 and 166 respectively extend from the surfaces 158 and 160 in plane 161 to the surfaces 162 and 163, respectively, so as to define a back-up 6pace between the plane 161 and the trough plane.
30The holding members 154 and 156 in operative holding relation cooperate with a rotary preform ' '~
~0~3~
rolling member 168 having a U-shaped groov~ 169 formed in it~ outer periphery. By advancing the rotary preform rolling member 168 with respect to the rotary holding unit 152 in a manner similar to the rotary member 68 previously described, an outer annulus of the circular piece 114 extending radlally outwardly ; beyond the surface 162 i~ cold-for~ed into a peripheral flange extending outwardly and then downwardly from a curved control port;on so as to provide a cross sectional configuration which opens generally radially inwardly. While Pinal configuration o~ the annular section which is cold-formed by the preform rolling member 168 could be of inverted se~i-circular shape, the configuration is more of an inverted U-shape having a pair o~ side-by-side annular wall portions 146 and 148 integrally interconnected by a central arcuate transitional wall portion 150.
It will be understood that the annular section provided by wall portions 146, 148, and 150 could be thickened by utilizing a thickening tool , similar to the tool 68; however, in th~ method ~ according to 8-lO, the next step is to cold-form the ', annular section into a series of teeth. This is accomplished by a rotary tooth ~orming tool unit 170 which is constructed and operated like the rotary tooth forming tool unit 70 to include a tooth forming periphery 172. The tool unit 170 is operated in the same manner as indicated before with at least portions of the sides of the teeth being free formed and the back-up space preferably Pilled with steel material, ~, a8 i8 shown in Figure 10. The finished toothed wheel ~1 ' , .. . . .. .
,. ~ , . . . .
3 3 ~
in this embod~ment i~ prePerably machined along both of the side defining plane~ which are aligned wi~h sur~aces 164 and 166 at the trough plane.
Re~erring now more particularly to Figures 11-13, there is shown therein another variation in the process according to the present invention. Again, Figure 11 illustrates a starting circular piece o steel sheet metal 2~4. The circular piece i~ then secured within a rotary holding unit, generally indicated at 252, which is constructed like the units : 52 and 152 previously described. As before, the rotary holding unit 252 includes two rotary holding members 254 and 256, having an inner pair o~ central wall engaging surfaces 258 and 260 extending to an inner plane 261, a pair of exterior peripheral surfaces 26~ and 263 and an outer pair of surfaces 264 ~nd 266 ext~ndin~ from the surfaces 258 and 260 to the surfaces 262 and 263 coincident with the tough plane.
.
The circular piece 214 is secured between 20 the members 254 and 256 in an operative relation so that a central wall 212 is engaged between the I surfaces 158 and 160. The outer annulus of the ; circular piece 214 extending beyond the inner plane ! 161 is thickened to provide an annular section 246 ,25 which together with a portion filling the back-up `,space constitutes a pre~orm. The cold-forming the annular section is accomplished by the operation of a rotary thickening tool 268 having a U-shaped thickening 810t 269 ~ormed in the exterior periphery thereo~ outwardly of the back-up 8paae defined by surfaces 264 and 266.
2~33~
By advancing the rotary thickening tool 268 in conjunction with the rotation of the rotary holding unit 252, the outer annulus of the circular piece 214 i8 thickened into a solid annular sect~on 246 having a width les~ than the width o~ the teeth to be formed.
It will b~ noted that, during the thicken~ng operation, the steel cold flows into substantial filling relation to the back-up space. The outer ~ diameter of the annular section 246 is slightly greater ; 10 than the crest diameter of the teeth to be formed.
.` . ., A series of teeth are cold formed in the solid annular section 246 by utilizing the flanged tooth forming tool unit 170 previously described in the same manner as previously described. Again both sides are machined in alignment with the surfaces 264 and 266 at the trough plane.
Referring now more particularly to Figures 14-17, there is shown therein still other modifications within the principles of the present invention. Here again, Figure 14 illustrates a startinq circular piece of steel sheet metal 314. The circular piece 314 i8 secured with a rotary holding unit 352 which is similar to the units 52, 152, and l 252 previously described. As before, the unit 352 i 25 includes t~o rotary holdin~ members 354 and 356. The holding members 354 and 356 when in operative relation with the piece 314 include an inner pair of central wall engaging surfaces 358 and 360 extending to an inner plane 361, a pair o~ exterior peripharal 30 surfaces 362 and 363 which are wi~hin a trough plane outwardly o~ the inner plane 361 and an outer pair of surfaces 364 and 366 which extend from the surfaces 2~33~
358 and 3~0 to the surfaces 362 and 363 so as to define a back-up spaced between the inner plane 361 and the trouqh plane.
As be~orej the circular piece 3~4 i~ secured in operat~ve relation ~etween the holding members 354 and 356 so as to extend generally axially outwardly from the inner plane 361 beyond the outer periphery of . a central portion of the circular piece which - constitutes a central wall 312. The ~nnulus of the circular pi~ce 314 is thickened into an initial solid annular ~ection 348 by utilizin~ an initial thickening tool 368 in the same manner as the thickening tool 268. Thereafter, a second thickening tool 36g is used `~ ~n a similar manner to cold-form the initial annular section 348 into a final ~olid annular section 349 having an axial flange 330 extending therefrom. As shown, the axial flange 330 is integral with the central wal} 312 and contacts the ~urface 366 of holding member 356 along its inner periphery and the .I 20 outer end thereof. ~he annular section 349 is integral with the end of the axial flange 330 which $s integral with the central wall 312. Again, it will be noted that the annular section 349 has a width greater than the predetermined sheet steel thickness but lass than the width of th~ teeth to be formed. Again, the steel ~aterial of the annular seation 349 .~ubstantially fill~ the back-up space defined by the ; sur~aces 364 and 366. Again, the outer periphery of the annular section 349 i~ slightly greater than the crest diam~ter of the teeth to be formed.
: , `
, ':
,~ .
.:
:
2~$33~
After the pre~orm i~ cold-formed ~ncluding central wall 312 and tha annular section 349 including axial flange 330, the port~on of the annular isection 349 outwardly of the back-up ~pace i8 cold-~ormed into a series of teeth. The teeth are formed by u8ing a : rotary tooth forming tool unit 370 ~imilar to the unit~ 70 and 170 in a 6imilar fashion except for one difference. In all of the embodiment~ hereto~ore - described, the outer periphery of the tooth-like projections on the tool periphery 72 or 172 have engaged or substantially engaged the exterior peripheral surfaces 62 and 63j 162 and 163, or 262 and 263, however in forming the teeth with the tooth-forming periphery 372, one side of the outer tips engages only the sur~ace 362. The other side engagas the outer surface of the flange 330.
.
This arrangement allows the sides of the teeth to be free formed as before. Also, as befor~, the back-up space is generally filled. With the ~` 20 provision of the flanqe 330, the toothed wheel is IJ finished in the same manner as the wheel 10.
, It thus will be seen that the obiects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodi~ent has been shown and described for the purpose of this invention and is subject to ohange without departure from such principles. Therefore, this invention includes all modification~ encompassed within the spirit and scope o~ the following claims.
i .
:
:,
in this embod~ment i~ prePerably machined along both of the side defining plane~ which are aligned wi~h sur~aces 164 and 166 at the trough plane.
Re~erring now more particularly to Figures 11-13, there is shown therein another variation in the process according to the present invention. Again, Figure 11 illustrates a starting circular piece o steel sheet metal 2~4. The circular piece i~ then secured within a rotary holding unit, generally indicated at 252, which is constructed like the units : 52 and 152 previously described. As before, the rotary holding unit 252 includes two rotary holding members 254 and 256, having an inner pair o~ central wall engaging surfaces 258 and 260 extending to an inner plane 261, a pair of exterior peripheral surfaces 26~ and 263 and an outer pair of surfaces 264 ~nd 266 ext~ndin~ from the surfaces 258 and 260 to the surfaces 262 and 263 coincident with the tough plane.
.
The circular piece 214 is secured between 20 the members 254 and 256 in an operative relation so that a central wall 212 is engaged between the I surfaces 158 and 160. The outer annulus of the ; circular piece 214 extending beyond the inner plane ! 161 is thickened to provide an annular section 246 ,25 which together with a portion filling the back-up `,space constitutes a pre~orm. The cold-forming the annular section is accomplished by the operation of a rotary thickening tool 268 having a U-shaped thickening 810t 269 ~ormed in the exterior periphery thereo~ outwardly of the back-up 8paae defined by surfaces 264 and 266.
2~33~
By advancing the rotary thickening tool 268 in conjunction with the rotation of the rotary holding unit 252, the outer annulus of the circular piece 214 i8 thickened into a solid annular sect~on 246 having a width les~ than the width o~ the teeth to be formed.
It will b~ noted that, during the thicken~ng operation, the steel cold flows into substantial filling relation to the back-up space. The outer ~ diameter of the annular section 246 is slightly greater ; 10 than the crest diameter of the teeth to be formed.
.` . ., A series of teeth are cold formed in the solid annular section 246 by utilizing the flanged tooth forming tool unit 170 previously described in the same manner as previously described. Again both sides are machined in alignment with the surfaces 264 and 266 at the trough plane.
Referring now more particularly to Figures 14-17, there is shown therein still other modifications within the principles of the present invention. Here again, Figure 14 illustrates a startinq circular piece of steel sheet metal 314. The circular piece 314 i8 secured with a rotary holding unit 352 which is similar to the units 52, 152, and l 252 previously described. As before, the unit 352 i 25 includes t~o rotary holdin~ members 354 and 356. The holding members 354 and 356 when in operative relation with the piece 314 include an inner pair of central wall engaging surfaces 358 and 360 extending to an inner plane 361, a pair o~ exterior peripharal 30 surfaces 362 and 363 which are wi~hin a trough plane outwardly o~ the inner plane 361 and an outer pair of surfaces 364 and 366 which extend from the surfaces 2~33~
358 and 3~0 to the surfaces 362 and 363 so as to define a back-up spaced between the inner plane 361 and the trouqh plane.
As be~orej the circular piece 3~4 i~ secured in operat~ve relation ~etween the holding members 354 and 356 so as to extend generally axially outwardly from the inner plane 361 beyond the outer periphery of . a central portion of the circular piece which - constitutes a central wall 312. The ~nnulus of the circular pi~ce 314 is thickened into an initial solid annular ~ection 348 by utilizin~ an initial thickening tool 368 in the same manner as the thickening tool 268. Thereafter, a second thickening tool 36g is used `~ ~n a similar manner to cold-form the initial annular section 348 into a final ~olid annular section 349 having an axial flange 330 extending therefrom. As shown, the axial flange 330 is integral with the central wal} 312 and contacts the ~urface 366 of holding member 356 along its inner periphery and the .I 20 outer end thereof. ~he annular section 349 is integral with the end of the axial flange 330 which $s integral with the central wall 312. Again, it will be noted that the annular section 349 has a width greater than the predetermined sheet steel thickness but lass than the width of th~ teeth to be formed. Again, the steel ~aterial of the annular seation 349 .~ubstantially fill~ the back-up space defined by the ; sur~aces 364 and 366. Again, the outer periphery of the annular section 349 i~ slightly greater than the crest diam~ter of the teeth to be formed.
: , `
, ':
,~ .
.:
:
2~$33~
After the pre~orm i~ cold-formed ~ncluding central wall 312 and tha annular section 349 including axial flange 330, the port~on of the annular isection 349 outwardly of the back-up ~pace i8 cold-~ormed into a series of teeth. The teeth are formed by u8ing a : rotary tooth forming tool unit 370 ~imilar to the unit~ 70 and 170 in a 6imilar fashion except for one difference. In all of the embodiment~ hereto~ore - described, the outer periphery of the tooth-like projections on the tool periphery 72 or 172 have engaged or substantially engaged the exterior peripheral surfaces 62 and 63j 162 and 163, or 262 and 263, however in forming the teeth with the tooth-forming periphery 372, one side of the outer tips engages only the sur~ace 362. The other side engagas the outer surface of the flange 330.
.
This arrangement allows the sides of the teeth to be free formed as before. Also, as befor~, the back-up space is generally filled. With the ~` 20 provision of the flanqe 330, the toothed wheel is IJ finished in the same manner as the wheel 10.
, It thus will be seen that the obiects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing preferred specific embodi~ent has been shown and described for the purpose of this invention and is subject to ohange without departure from such principles. Therefore, this invention includes all modification~ encompassed within the spirit and scope o~ the following claims.
i .
:
:,
Claims (11)
1. A method of forming a one-piece sheet metal toothed wheel including a central sheet metal wall of predetermined thickness and a series of cold-formed integral teeth on the periphery of the central wall defined by troughs extending radially inwardly therebetween to a cylindrical trough plane concentric with an axis of the central wall, said series of cold-formed integral teeth having an operative width defined by spaced tooth side defining planes, said method utilizing (1) a rotary holding unit which provides, when in holding relation, an inner pair of opposed central wall-engaginq surfaces extending generally radially outwardly to a cylindrical inner plane spaced inwardly from an outer cylindrical plane of a size equal to said trough plane and an outer pair of back-up surfaces extending from said inner pair of opposed central wall-engaging surfaces at said inner plane to said outer plane where said outer pair of surfaces are spaced apart a predetermined distance which is greater than the spacing between said inner pair of surfaces so as to define a back-up space within an annulus between said inner and outer planes and (2) a rotary tooth-forming tool unit having a rotational axis and a tooth-forming periphery extending annularly about said rotational axis, said method comprising the steps of cold-forming a circular piece of sheet metal into a preform having an outer annular section of generally uniform cross-sectional configuration and an integral sheet metal central wall generally of said predetermined thickness extending generally radially inwardly from the outer annular section toward a preform axis, said outer annular section having (1) a width greater than said predetermined thickness but no greater than said predetermined distance, and (2) an outer periphery extending beyond said trough plane which will allow a meshing action with the tooth-forming periphery of the tooth-forming tool unit, rotating (1) said rotary holding unit with said preform secured thereto about the preform axis and an inner portion of said outer annular section within said back-up space and an outer portion of said outer annular section extending radially outwardly of said back-up pace, and (2) said tooth-forming tool unit about the rotational axis thereof in a predetermined rotational relation wherein said axes are parallel and the rotational speeds are synchronized, and while said rotary holding unit with said preform secured thereto and said tooth-forming tool unit are in said predetermined rotational relation affecting a relative movement between said units and the axes thereof in a direction toward one another to engage the tooth-forming periphery of the tooth-forming tool unit in cooperating metal-deforming relation with the outer portion of said outer annular section inwardly of the exterior periphery thereof until the sheet metal of the outer portion of the annular section is cold-formed into said series of teeth and displaced from the troughs therebetween so that after the series of teeth are cold-formed the toothed wheel includes a back-up portion having surfaces conforming to an outer extent of each of said outer pair of surfaces defining said back-up space, the peripheries of said series of teeth being cold-formed by rolling contact with the tooth-forming periphery of the tooth-forming tool unit and the sides of the series of teeth including portions disposed outwardly beyond said spaced tooth side defining planes being free-formed without surface contact by the axially outward movement of the metal defining the outer portion of said outer annular section.
2. A method as defined in claim 1 wherein said rotary holding tool unit further provides a pair of cylindrical exterior peripheral surfaces extending axially in opposite directions from said outer pair of surfaces within said outer plane, and wherein at the end of the relative movement between said units towards one another to engage the tooth forming periphery of the tooth forming tool unit in cooperating relation with the outer portion of said outer annular section, the tooth forming periphery includes trough forming teeth-like projections having exterior tips which extend to said trough plane and substantially engage the exterior periphery surfaces of said rotary holding unit.
3. A method as defined in claim 2 wherein the spaced tooth side defining planes pass generally through the outer pair of surfaces spaced apart within said outer plane and the free-formed portions of the sides of said series of teeth at least along one common side are machined so that the machined sides of the teeth on said one common side are disposed in a common plane constituting one of said spaced tooth side defining planes.
4. A method as defined in claim 3 wherein the free-formed portions of both sides of said series of teeth are machined in common planes constituting both of said spaced tooth side defining planes.
5. A method as defined in claim 2 wherein said preform is formed by cold-forming a first annular wall portion in side by-side relation to a second annular wall portion integral with a central portion of the circular piece of sheet metal so that the two side-by-side annular wall portions are integrally interconnected at their outer peripheries so as to form a non-thickened preform.
6. A method as defined in claim 5 wherein said non-thickened preform is cold-formed into a thickened final preform while secured to said rotary holding unit with said first annular wall portion overlying the back-up space by cold-rolling the integrally interconnected outer peripheries of said two side-by-side annular wall portions radially inwardly to thicken the outer portion of the annular wall portions and the integral interconnection therebetween.
7. The method as claimed in claim 6 wherein said non-thickened preform is formed by cold-forming an outer annular portion of the circular piece of sheet metal into a peripheral flange extending axially from a central portion thereof, cold-forming a portion of the peripheral flange into said two side-by-side annular wall portions integrally extending outwardly of a remaining portion of said peripheral flange, said central portion providing said central wall, said pair of side-by-side integrally interconnected annular wall portions providing said annular section, and the remaining portion of the peripheral flange providing a pulse ring.
8. The method as claimed in claim 7 wherein said predetermined rotational relation includes a simultaneous synchronous rotation of said units in opposite directional meshing engagement to one another through a multiplicity of revolutions including reversal of directions.
9. A method as defined in claim 2 wherein the circular piece of sheet metal is cold-formed into said preform while secured with the rotary holding unit by cold-rolling an outer annulus of the circular piece of sheet metal radially inwardly to an extent sufficient to thicken the outer annulus into said annular section.
10. The method as claimed in claim 2 wherein said preform is formed by cold-forming an outer annulus of the circular piece of sheet metal into a peripheral flange extending outwardly and then downwardly from a curved central portion thereof so as to provide a cross-sectional configuration form which opens generally radially inwardly, said central portion providing said central wall and said peripheral flange of arcuate cross-section providing said annular section.
11. The method as claimed in claim 1 wherein said preform is formed by securing a circular piece of sheet steel with the rotary holding unit so that an annulus extends outwardly of said inner plane, thickening the annulus into an initial solid annular section by cold-rolling, and then cold-rolling the initial solid annular section into a final solid annular section with an axial flange portion extending therefrom.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/935,388 | 1992-08-24 | ||
| US07/935,388 US5237744A (en) | 1992-02-19 | 1992-08-26 | Method of cold-forming toothed wheels |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2088336A1 true CA2088336A1 (en) | 1994-02-25 |
Family
ID=25467030
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2088336 Abandoned CA2088336A1 (en) | 1992-08-24 | 1993-01-28 | Cold-forming of toothed wheels from sheet steel |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2088336A1 (en) |
-
1993
- 1993-01-28 CA CA 2088336 patent/CA2088336A1/en not_active Abandoned
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