CA1228223A - Die and method for splining thin-wall power transmitting members - Google Patents

Abstract

POWER TRANSMITTING MEMBERS

ABSTRACT

An improved die (20) and method for splining a thin-wall sleeve (22) of a power transmitting member by meshing die teeth (32) and teeth (28) of a toothed mandrel (26) on which the sleeve is mounted between the meshing teeth. The die (20) is preferably em-bodied by an elongated die rack and includes a toothed forming face (30) having a plurality of leading tooth groups (32a,32b) of a progressively changing height from one tooth to the next tooth of the same group. Each of the tooth groups has a length for splining an arcuate segment of the sleeve of no more than ninety degrees and has an average tooth height that is approximately equal to the average tooth height of each other leading tooth group. A stepped tooth group (32c) and a trailing tooth group (32d) of full teeth complete the thin-wall splining after the initial partial splining performed by the leading tooth groups. In the pre-ferred construction, there are three leading tooth groups (32a) each of which has teeth of a precedes sively increasing height and there are three leading tooth groups (32b) each of which has teeth of a progressively decreasing height. Between the leading tooth groups and the stepped tooth group which precedes the trailing tooth group, the die rack (20) has a sizing recess (74) of a length that permits the trail-ing tooth group to commence the full splining in a manner that-eliminates any out of roundness of the splined sleeve.

Description

DIE AND I~ETI~OD FOR SPLI~ING THIN-WALL
POWER ~RA~'SMITTING 25E~BERS
_ _ _ _ _ ~ _ _ _ _ _ TEC~NICAL FIELD

This invention relates to a die and a method for splining thin-wall power transmitting members by a rolling operation~
BACKGROU~D ART

United States Patent 3,9~2,415, which is assigned to the assignee of the present application, discloses a rolling operation for forming splines in thin-wall sleeves of power transmitting members. This rolling operation is performed by mounting the thin-wall sleeve On a toothed mandrel that is located between a pair of toothed dies. Movement of the pair of dies ~ in opposite directions as each other meshes the die and mandrel teeth with the sleeve therebetween to form the splines at diametrically opposite locations while the mandrel rotates in coordination with the die movement. Vehicle automatic transmissions con-ventionally incorporate the type of splined sleeve that can be formed by this thin-wall spline rolling operation much more economically than impact splining that was previously utilized to perform the splining.

~ nited States Patent 4,028,922, which is also assianed to the assignee of the present application, discloses dies which have a particular toothed ~orm-ing face construction for performing thin-wall sleeve splining in accordance with the prosess discussed ~2~ 3 above. These dies are disclosed as either being of the straight gear rack type or of a rotary type such as disclosed by United States Paent 4,0~5,988 which is also assigned to the assignee of the present application.

United States Patent 4,155,237, which is likewise assigned to the assignee of the present application, discloses a thin-wall sleeve splining machine of the type discussed above with an automatic loader used to mount and remove the sleeve from the mandrel. Loading and unloading members of the machine loader cooperate with each other to move the sleeve onto the mandrel for the splining operation and to thereafter remove the splined sleeve in preparation for the next cycle.

DISCLOSURE OF INVENTION

The present invention provides in a tubed die for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing the die teeth and teeth of a toothed mandrel on which the sleeve is mounted between the meshing teeth so as to thereby form thin-wall splines in the sleeve as the mandrel rotates about a central axis, the die including a plurality of leading toothed groups each of which includes partial teeth of a progressively changing height from one tooth to the next tooth of the same group and each of the leading tootll groups having a length for splining an arcuate segment of the sleeve of no more than 90 and having an average tooth height that is approximately equal to the average tooth height of each other leading tooth group. The die further includes a trailing tooth group of full teeth for completing the thin-wall splining.

The objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE l is a side elevation view of a toothed die for performing thin-wall sleeve splining in accordance with the present invention;

FIGURE 2 is an enlarged view illustrating one leading tooth group of the die which has teeth of a proyressively increasing height in a direction from the leading end of the die toward its trailing end;

FIGURE 3 is an enlarged view of another leading tooth group of the die which has teeth of a progres-.

~-3~ -4-sively decreasing height in a direction from the leading end of the die toward its trailing end;

FIGURE 4 is an enlarged view illustrating teeth of a ~tepped tooth group of the die;

FIGURE 5 is an enlarged view illu~trating teeth of a trailing toot~ group of the die ~djacent its trailing end;

FIGURE 6 is a front elevation view of a machine with which a pair of the dies are utilized to perform the thin-wall ~pline orming met~od of the invention;

FIGURE 7 is a ~ec~ional view illustrating a toothed mandrel on which the thi~-wall sleeve is mounted for the splining by the pair of dies;

FIGURE 8 illustrates the manner in which the die and mandrel teeth mesh with the thin-wall sleeve therebetween ~o form the ~plines FIGURE 9 is a schematic view which illustrates a ~lightly out of round condition of the sleeve after an initial partial splining thereof by the leading tooth groups shown in FIGURES 2 and 3 and prior to oompletion of the splining by the trailing tooth groups shown in FIGURES 4 and 5;

FIGURE 10 is a view of the sleeve after it has been partially splined by the one leading tooth group shown in FIGURE 2;

FIGURE 11 is a partial view of the sleeve after it has been splined ~y both of the leading ~ooth ~roups ~hown in FIGURES 2 ~nd 3; and .

~-336 -5~ ?~

~ IGURE 12 is a partial view of ~he sleeve af~er it has been fully ~plined by the die rack.
s BEST MODE FO~ CA~RYING OUT THE XNVENTION

Referrin~ to FIGU~E 1 of ~he drawings, a toothed die for forming thin~wall splines in accor-dance with the invention is generally indicated byreference numeral 20. An annular thin-wall sleeve 22 of a power transmitting member 24 shown in FI~-URE 6 is initially mounted on a toothed mandrel 26 which ifi rotatable about a central axi~ A and has teeth ~8 that engage the inner surface of the mounted sleeve. Die 20 has a toothed forming face 30 whose teeth 32 mesh with the mandrel teeth 28 as shown in FIGURE 8 with the sleeve 22 therebetween in order to form thin-wall splines 34 in a manner which is hereinafter more fully described.
~ ith reference to FIGURES 1 through 3~ the too~hed forming face 30 of die 20 includes a plu-rality of leading tooth groups 32a and a plurality 25 of leading tooth groups 32b each of which includes partial teeth ~f ~ progressively changing height from one tooth to the next tooth of the xame group.
Each of the leading tooth groups 32a and 32b has a length for splining an arcuate segment of the sleeve of no more than ninety degrees and has an average tooth height that is ap~roximately equal to the average tooth height of each other leading tooth group. During the initial ~plining, leading tooth groups 32a and 32b initially form partial splines of a progressivel~ changing depth over arcua~e seg-ments of the sleeve of less than ninety degrees.
Forming face 30 of die 20 also includes a stepped tooth group 32c and a trailing tooth group 32d of full teeth which complete the thin~ s~l.in~.n~
.

P-336 -6~

As illustrated in FIGURE 5, a machine 36 having apparatus for performing the thin-wall splining oper-ation includes upper and lower based 38 and 40 thatproject forwardly from a rear connecting portion 42 to define a work space 44 in which the splining is performed. A pair of upper and lower cooperable dies 20 which perform the splining are each embodied by an elongated die rack having a metallic body 46 that is made from a suitable tool steel. Each of the die racks 20 has a leading end 48 and a -trailing end 50 between which the toothed forming face 30 thereof extends. At the leading end 48 of each die rack 20, a loading recess 52 is formed to permit loading of a sleeve 22 to be splined on the toothed mandrel 26 with the racks in their end-to-end position shown.
End retention lugs 54 at the leading and trailing ends 48 and 50 of each die rack body 46 are secured by associated bolted clamps 56 to a rack box 58 which is mounted by an unshown movable slide on the associated machine base 38 or 40.

A schematically indicated drive mechanism 60 of machine 36 shown in FIGURE 5 is preferably of the type disclosed by United States Patent 3,793,866 and initially moves the die racks 20 along parallel paths in opposite directions as each other as indi-cated by arrows 62. This movement of the die racks along the upper and lower bases 38 and 40 engages the toothed forming faces 30 of the racks with the sleeve 22 at diametrically opposite locations such that the die teeth mesh with the mandrel teeth to perform the thin-wall splining of the sleeve. Drive mechanism 60 thereafter reciprocally moves the die P~336 7-racks 20 in the opposite directions shown by arrows 64 a partial extent for unloading as is hereinafter described and subsequently moves the die racks back to their initial position shown in preparation for the next cycle.

With reference FIGURE 7, it should be noted that whereas normal engineering terminology defines a thin-wall construction as including an internal diameter "D" to wall thickness ratio "t" of at least ten, this ratio is at least twenty for the type of splining involved with this invention and normally on the order of fifty or more. For example, the internal di.ameter may be on the order of about four inches with a wall thickness of about 1/16 of an inch so as to provide a ratio of sixty-four.

As seen in FIGURE 1, each die rack 20 has a rectilinear pitch line 66 along which the tooth groups 32a, 32b, 32c, and 32d are disposed. As illustrated in FIGURE 8, pitch line 66 of each die rack 20 is tangent to the pitch circle 68 of the toothed mandrel 26 where the mandrel teeth 28 and the rack teeth 32 have the same rate of movement.
As illustrated in FIGURES 2 and 3, each of the leading tooth groups 32a and 32b includes partial teeth having angled tips 70 that extend in an angular relationship to the pitch line 66 in the same plane : 30 as each other. These partial teeth can be readily formed by starting with a toothed rack having full teeth and then grinding the tooth tips with a grinding wheel to provide the angled tips 70.

2~

As seen in FIGURE 1, die rack 20 includes three of the leading tooth groups 32a immediately adjacent its leading end 48. Each leading tooth group 32a has length for splining an arcuate segment of sixty degrees of the annular thin-wall sleeve. As illustrated in FIGURE 2, each leading tooth group 32a includes six teeth al, a2, a3, a4, a5, and a6 of a progressively increasing height in a direction from the leading end of the rack toward the trailing end of the rack. After the splining has been performed a sufficient extent to engage each one-half of the thin-wall sleeve with all three leading tooth groups 32a on one of the die racks, the partially splined sleeve 22 has the configuration illustrated in FIGURE
10 wherein partial splines al, a2, a3, a 4, a5, and a6 are provided over each sixty degree arcuate segment of the sleeve. These partial splines are r~spectively formed by the partial teeth shown in FIGURE 2 with corresponding re~erence identifications and have progressive depths that correspond to the heights of the partial teeth that form each partial spline.
As seen in FIGURE 1, there are three of the leading tooth groups 32b which are located toward the trailing end 50 of the rack from the leading tooth groups 32a. Each of the leading tooth groups 32b as illustrated in FIGURE 3 has teeth bl, b2, b3, b4, b5, and b6 of a progressively decreasing height in a direction from the leading end of the rack toward the trailing end of the rack. As the splining con-tinues such that khe three leading tooth groups 32b on each rack engage one half of the circumference of the partially splined sleeve, the three taller teeth ~L2~ 3 bl, b2, and b3 of each leading tooth group 32b further partially form each of the three shallower splines al, a2, and a3 on each sixty degree arcuat~
sleeve segment as illustrated in FIGURE 10 so as to provide the partial splines bl, b2, and b3 as illustrated in FIGURE 11. The three shorter teeth b4, b5, and b6 of each leading tooth group 32b do not perform any further spline forming as these shorter teeth respectively mesh with the deeper splines a4, a5, and a6 that are already deeper than the shorter teeth. Thus, each sixty degree arcuate segment of the partially splined sleeve after forming by both leading tooth groups 32a and 32b as illustrated in FIGURE 10 has three partial splines bl, b2, and b3 which are symmetrical about the miclpoint of the segment with the three other partial splines a4, a5, and a6.

After the partial splining by the leading tooth groups 32a and 32b illustrated in FIGURE 1, the sleeve 22 normally has a slightly out of round shape as schematically shown exaggerated extent in FIGURE 9 for purposes of illustration. The major and minor diameters of the partially splined sleeve 22 are iden-tified by D1 and D2 and extend perpendicular to eachother with an intersection at the central axis A, and the intersections of the minor axis D2 with the sleeve 22 at diametrically opposite locations correspond to the *inal locations of engagement of the teeth 32b of the die racks with the sleeve. Completion o* the splining of the partially splined sleeve preferably commences at one of the sets of diametrically opposite locations 72 which are located sixty degrees from the minor axis D2, i.e. two thirds of the distance from the minor axis D2 toward the major axis Dl. This is accomplished as illustrated in FIGURE 1 by providing the die rack with a sizing recess 74 that is located 2~ 3 between the last leading tooth group 32b and the stepped tooth group 32c and which has a length equal to one sixth of the circumference of the sleeve to be splined. A suitable coordinating gear that is rota-tively coupled with the toothed mandrel and meshedwith a pair of coordinating racks that move with the forming racks 20 provides mandrel rotation through the sizing recess 74 such that the first tooth C1 (FIGURE
4) of the stepped tooth group 32c provides the initial engagement as previously mentioned at the associated location 72 on the sleeve. It has been found that the thin-wall sleeve splining performed with a die sizing recess 74 as described provides best results in imparting roundness to the sleeve upon meshing thereof with the stepped tooth group 32c and the trailing tooth group 32d as is hereinafter more fully described.

With reference to FIGURE 1, the leading end of the recess 74 includes a root support 75 that corresponds in positioning to the root surface between the teeth 32a and 32b of the leading tooth groups.
This support 75 has been found to be useful in supporting the last spline formed by the leading tooth group 32b closest to the sizing recess 74.
As illustrated in FIGURE 4, the stepped tooth group 32c of the die forming face is located between the recess 74 and the trailing tooth group 32d of full teeth. This stepped tooth group 32c includes teeth cl through c18 of a progressively increasing height from the sizing recess 74 toward the trailing tooth group 32d of full teeth. Best results are achieved with the stepped tooth group having a length equal to about one half the circumference of the sleeve 22. Also, the shortest tooth cl preferably has P-336 ~

a heiyht on the order of about slightly greater than one half to about three fourths of the height of the trailing tooth group 32d of full teeth, and the teeth c2 through c18 have progressively increasing heights in equal steps toward the group of full teeth. In providing the stepped tooth group 32c, it is best to start with teeth of the same form positioning on the die rack 20 as the teeth of trailing tooth group 32d.
The tips of the teeth are then ground off to provide the stepped tooth group 32c.

The trailing tooth group 32d of full teeth 32 shown in FIGURE 5 meshes with the sleeve 22 after the stepped tooth group to thereby provide forming of the sleeve from the partially splined condition to the fully splined condition shown in FIGURE 12. After the completion of the splining, reverse movement of the die racks positions the splined sleeve 22 within the sizing recess 74 to permit removal thereof from the toothed mandrel prior to rack movement back to the initial position in preparation for the next cycle.

As illustrated in FIGURES 2 and 3, the shortest partial teeth al and b6 of the groups of partial teeth 32a and 32b each has a height of about two thirds of the height of the tallest partial teeth a6 and bl. Thus, about one third of the height of each shortest tooth al an b6 is ground off. Each of the tallest partial teeth a6 and bl merely has its tip 70 ground to the angular orientation shown with a peak of the same height as prior to the grinding of the partial teeth. Partial teeth a2, a3, a4, and a5 of tooth group 32a and partial teeth b2, b3, b4, and b5 of tooth group 32b have progressively changing heights directly proportional to their locations between the shortest and tallest partial teeth.

~.~2~223 The trailing group 32d of full teeth 32 shown in FIGURE 5 preferably have a greater height and/or are positioned with respect to even the tallest of the partial teeth so as to have greater penetration and thereby complete the splining. The degree of greater penetration of the full teeth can vary and must be selected to provide best results Eor the particular thin-wall splining to be performed. In some instances, only several thousandths of an inch of greater pene-tration by the full teeth is sufficient. Others willrequire a greater penetration by the full teeth of the trailing tooth group, such as on the order of seventy thousandths of an inch or more.

With reference to FIGURE 8, the formed thin-wall splines 34 preferably have about 50% of each spline located within the pitch circle 68 and about 50% of each spline located outside of the pitch circle. It has been found that best results are achieved when the thin wall splining is performed in this manner.

The invention also involves the method by which the thin-wall splines 34 are formed in the annular sleeve 22 of power transmitting member 24 by meshing the teeth of the pair of dies 20 with the teeth 28 of the mandrel 26 on which the sleeve is mounted between the meshing teeth. The important step in accordance with this invention is the initial forming of the complete sleeve 22 in arcuate segments of no more than ninety degrees with partial splines of a progressively changing depth along each segment with the average spline depth therealong approximately equal to the average spline depth along each other segment. After this initial partial spline forming, the full forming of the splines is performed to complete the spline forming operation.

~, .
!

P-336 ~ 13 ~ ~ 3 In performing the method, it is preferable for the sleeve to be initially formed with partial splines of progressively changing depth along arcuate segments of sixty degrees. As such, there are six such seg-ments on the partially splined sleeve prior to the completion of the splining by the full teeth of the die racks in the manner previously described. It is also preferable fox the shallower splines al, a2, and a3 along each partially formed arcuate segment to be further progressively formed in the opposite direc-tion as the deeper splines a4, a5, and a6 such that each segment has-the configuration shown in FIGURE
11 with partial splines bl, b2, and b3 which are symmetrical with the partial splines a4, a5, and a6 on opposite sides of the midpoint of the arcuate segment~. Out of roundness is also eliminated by the spline forming method by commencing the full forming of the splines at the locations 72 which are located along the sleeve 22 about two thirds of the distance from the minor diameter D2 toward the major diameter Dl of the out of round shape of the sleeve after the partial forming as shown in FIGU~E 9.
Thin-wall splining can be performed by the die 20 and method disclosed on thin-~all metal sleeves of harder and tougher metal than was previously pos-sible. As such, more durable splined thin-wall sleeves 22 can be provided as mzy be required for certain applications.

~ Jhile the best mode ~or carrying out the inven~
tion has been described in detail, those familiar with the art to which this invention relates will recognize various alternative ~-ays for practicing the present invention as defined by the following claims~

Claims (20)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a toothed die for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing the die teeth and teeth of a toothed mandrel on which the sleeve is mounted between the meshing teeth so as to thereby form thin-wall splines in the sleeve as the mandrel rotates about a central axis, said die comprising: a plurality of leading tooth groups each of which includes partial teeth of a progressively changing height from one tooth to the next tooth of the same group; each of said leading tooth groups having an average tooth height that is approximately equal to the average tooth height of each other leading tooth group; and a trailing tooth group of full teeth for completing the thin-wall splining.

2. A die as in Claim 1 which comprises an elongated die rack having leading and trailing ends and also having a rectilinear pitch line along which the leading and trailing tooth groups extend.

3. A die as in Claim 2 wherein the partial teeth of each leading tooth group have angled tips that extend in an angular relationship to the pitch line in the same plane as each other.

4. A die as in Claim 2 wherein at least two of the leading tooth groups each have teeth of a progressively increasing height in a direction from the leading end of the rack toward the trailing end of the rack.

5. A die as in Claim 2 wherein at least two of the leading tooth groups each have teeth of a progressively decreasing height in a direction from the leading end of the rack toward the trailing end of the rack.

6. A die as in Claim 2 wherein at least one of the leading tooth groups has teeth of a progressively increasing height in a direction from the leading end of the rack toward the trailing end of the rack, and wherein at least one other of the leading tooth groups has teeth of a progressively decreasing height in a direction from the leading end of the rack toward the trailing end of the rack.

7. A die as in Claim 2 wherein a plurality of the leading tooth groups each have teeth of a progressively increasing height in a direction from the leading end of the rack toward the trailing end of the rack, and wherein another plurality of the leading tooth groups each have teeth of a progressively decreasing height in a direction from the leading end of the rack toward the trailing end of the rack.

8. A die as in Claim 7 wherein the tooth groups having the teeth of progressively increasing height are located immediately adjacent the leading end of the rack, and wherein the tooth groups having the teeth of progressively decreasing height are located toward the trailing end of the rack from the tooth groups having the teeth of progressively increasing height.

p-336

9. A die as in Claim 1, further including a sizing recess between the leading tooth groups and the trailing tooth group.

10. A die as in Claim 9 further including a stepped tooth group located between the sizing recess and the trailing tooth group of full teeth;
and said stepped tooth group having teeth of a progressively increasing height from the sizing recess toward the trailing tooth group of full teeth.

11. A die as in Claim 10 wherein the sizing recess has a length equal to about one sixth the circumference of sleeve to be splined, and the stepped tooth group having a length equal to about one half the circumference of the sleeve.

12. In a toothed die rack for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing the rack teeth and teeth of a toothed mandrel on which the sleeve is mounted between the meshing teeth so as to thereby form thin-wall splines in the sleeve as the mandrel rotates about a central axis, said die rack comprising: an elongated rack body having leading and trailing ends and a toothed forming face extending therebetween; said toothed forming face having a rectilinear pitch line and teeth positioned along the pitch line; the toothed forming face having a plurality of leading tooth groups each of which includes partial teeth of a progressively increasing height from one tooth to the next tooth of the same group in a direction from the leading end of the rack body toward the trailing end thereof; each of said leading tooth groups having an average tooth height that is approximately equal to the average tooth height of each other leading tooth group; the toothed forming face including a trailing tooth group of full teeth for completing the thin-wall splining; and the toothed forming face including a sizing recess between the leading and trailing tooth groups.

13. In a toothed die rack for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing the rack teeth and teeth of a toothed mandrel on which the sleeve is mounted between the meshing teeth so as to thereby form thin-wall splines in the sleeve as the mandrel rotates about a central axis, said die rack comprising: an elongated rack body having leading and trailing ends and a toothed forming face extending therebetween; said toothed forming face having a rectilinear pitch line and teeth positioned along the pitch line; the toothed forming face having a plurality of leading tooth groups each of which includes partial teeth of a progressively decreasing height from one tooth to the next tooth of the same group in a direction from the leading end of the rack body toward the trailing end thereof; each of said leading tooth groups having an average tooth height that is approximately equal to the average tooth height of each other leading tooth group; the toothed forming face including a trailing tooth group of full teeth for completing the thin-wall splining; the toothed forming face including a sizing recess between the leading trailing tooth groups; and the toothed forming face including a stepped tooth group located between the sizing recess and the trailing tooth group of full teeth and having teeth of a progressively increasing height from the sizing recess toward the trailing tooth group of full teeth.

14. In a toothed die rack for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing the rack teeth and teeth of a toothed mandrel on which the sleeve is mounted between the meshing teeth so as to thereby form thin-wall splines in the sleeve as the mandrel rotates about a central axis, said die rack comprising: an elongated rack body having leading and trailing ends and a toothed forming face having a rectilinear pitch line and teeth positioned along the pitch line; the toothed forming face having a plurality of leading tooth groups at least two of which include partial teeth of a progressively increasing height from one tooth to the next tooth of the same group in a direction from the leading end of the rack body toward the trailing end thereof; at least two other of the leading tooth groups each including partial teeth of a progressively decreasing height from one tooth to the next tooth of the same group in a direction from the leading end of the rack body toward the trailing end thereof; each of said leading tooth groups having an average tooth height that is approximately equal to the average tooth height of each other leading tooth group; the toothed forming face including a trailing tooth group of full teeth for completing the thin-wall splining; the toothed forming face including a sizing recess located between the leading and trailing tooth groups and having a length equal to about one sixth the circumference of the sleeve to be splined; the toothed forming face including a stepped tooth group located between the sizing recess and the trailing tooth group of full teeth; the stepped tooth group having teeth of a progressively increasing height from the sizing recess toward the trailing tooth group of full teeth; and the stepped tooth group having a length equal to about one half the circumference of the sleeve to be splined.

15. A die rack as in Claim 12 wherein the partial teeth of each leading tooth group have angled tips that extend in an angular relationship to the pitch line in the same plane as each other.

16. In a toothed die rack for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing the rack teeth and teeth of a toothed mandrel on which the sleeve is mounted between the meshing teeth so as to thereby form thin-wall splines in the sleeve as the mandrel rotates about a central axis, said die rack comprising: an elongated rack body having leading and trailing ends and a toothed forming face extending therebetween; said toothed forming face having a rectilinear pitch line and teeth positioned along the pitch line; the toothed forming face having six leading tooth groups each of which includes partial teeth of progressively changing height from one tooth to the next tooth of the same group; each of said leading tooth groups having an average tooth height that is approximately equal to the average tooth height of each other leading tooth group; a first three of the leading tooth groups being located immediately adjacent the leading end of the rack body and each having teeth of a progressively increasing height in a direction from the leading end of the rack body toward the trailing end thereof; the other three leading tooth groups being located toward trailing end of the rack body and the first three groups and each having teeth of a progressively increasing height in a direction from the leading end of the rack body toward the trailing end thereof; the other three leading tooth groups being located toward the trailing end of the rack body from the first three groups and each having teeth of a progressively decreasing height in a direction from the leading end of the rack body toward the trailing end thereof; the teeth of each of said leading tooth groups having angled tips that extend in an angular relationship to the pitch line in the same plane as each other; a trailing tooth group of full teeth adjacent the trailing end of the rack body for completing the thin-wall splining; the toothed forming face including a sizing recess located between the leading and trailing tooth groups and having a length equal to about one sixth the circumference of the sleeve to be splined; the toothed forming face including a stepped tooth group located between the sizing recess and the trailing tooth group of full teeth, the stepped tooth group having teeth of a progressively increasing height from the sizing recess toward the trailing tooth p-336 group of full teeth; and the stepped tooth group having a length equal to about one half the circumference of the sleeve to be splined.

17. In a method for forming splines in a thin-wall annular sleeve of a power transmitting member by meshing teeth of a pair of dies and teeth of a rotatable mandrel on which the sleeve is mounted between the meshing teeth so as to thereby from thin-wall splines in the sleeve as the mandrel rotates about a central axis, the improvement comprising: initially forming the complete sleeve in arcuate segments of no more than ninety degrees with partial splines of a progressively changing depth along each segment with the average spline depth along each segment being approximately equal to the average spline depth along each other segment; and thereafter fully forming the splines to complete the spline forming operation.

18. A method as in Claim 17 wherein the sleeve is initially formed with partial splines of progressively changing depths along arcuate segments of sixty degrees.

19. A method as in Claim 17 wherein the shallower splines of less than the average depth along each partially formed arcuate segment are further progressively formed in the opposite direction as the deeper splines thereof prior to the full forming of the splines.

20. A method as in Claim 17 wherein the full forming of the splines commences about two thirds of the distance from the minor diameter to the major diameter of an out of round shape of the sleeve after the partial spline forming.

22.