NET FORMED GEAR MEMBER AND METHOD OF MANUFACTURE

Abstract

A gear member for an automatically shiftable vehicular transmission is provided having a gear body with a generally cylindrical outer surface having a plurality of radially outwardly extending gear teeth formed thereon. An inner surface is generally coaxially disposed with respect to the generally cylindrical outer surface and extends for at least a portion of the gear body. Additionally, a plurality of radially inwardly extending splines is formed on at least a portion of the inner surface. At least one of the plurality of radially outwardly extending gear teeth and the plurality of radially inwardly extending splines are cold extruded. A method of forming the gear member is also provided including forming a generally tubular blank by reverse extrusion of a generally cylindrical slug. Subsequently, a plurality gear teeth are formed on at least a portion of the generally tubular blank by cold extrusion to form the gear member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a net formed input sun gear member for an automatically shiftable vehicular transmission consistent with the present invention and formed by the method of the present invention;

FIG. 2 a is a cross sectional side view of a slug used to create the net formed input sun gear member of FIG. 1;

FIG. 2 b is a cross sectional side view of a gear blank formed from the slug of FIG. 2a by a reverse or backward extrusion process;

FIG. 2 c is a cross sectional side view of the gear blank of FIG. 2b following removal of the web formed during the backward extrusion process;

FIG. 2 d is a cross sectional side view of the net formed input sun gear member of FIG. 1 following the formation, from the blank of FIG. 2c, of a plurality of radially outwardly extending gear teeth and a plurality of radially inwardly extending splines;

FIG. 2 e is a cross sectional side view of the net formed input sun gear member of FIG. 2d following contouring; and

FIG. 2 f is a cross sectional side view of the net formed input sun gear member of FIG. 2e following formation of a plurality of radially outwardly extending splines and a plurality of openings or holes.

Claims

1. A net formed gear member comprising: a gear body having a generally cylindrical outer surface with a plurality of radially outwardly extending gear teeth formed thereon;an inner surface generally coaxially disposed with respect to said generally cylindrical outer surface and wherein said inner surface extends for at least a portion of said gear body;a plurality of radially inwardly extending splines formed on at least a portion of said inner surface; andwherein at least one of said plurality of radially outwardly extending gear teeth and at least one of said plurality of radially inwardly extending splines are cold extruded, thereby reducing the machining steps required to produce the net formed gear member.

2. The gear member of claim 1, further comprising: a plurality of radially outwardly extending splines formed on at least a portion of said generally cylindrical outer surface axially adjacent said plurality of radially outwardly extending gear teeth.

3. The gear member of claim 1, wherein said outwardly extending teeth are helical in form and said gear body is formed from steel and sufficiently configured for use as an input sun gear for an automatically shiftable vehicular transmission.

4. The gear member of claim 1, wherein said gear body defines at least one hole operable to communicate fluid between said inner surface and said generally cylindrical outer surface.

5. The gear member of claim 1, wherein said gear body is heat treated such that said gear body has a case depth and said gear body has a core hardness between 32 and 44 Rockwell C.

6. The gear member of claim 2, wherein said plurality of radially outwardly extending splines are broached.

7. A method of forming a gear member comprising: forming a generally tubular blank by reverse extrusion of a generally cylindrical slug, wherein said generally tubular blank has an inner surface and an outer surface; andforming a plurality of radially outwardly extending gear teeth on at least a portion of said outer surface by cold extrusion to form the gear member.

8. The method of claim 7, further comprising: annealing said generally tubular blank prior to forming said plurality of radially outwardly extending gear teeth.

9. The method of claim 7, further comprising: forming a plurality of radially inwardly extending splines on at least a portion of said inner surface by cold extrusion.

10. The method of claim 7, further comprising: coating said generally cylindrical slug with a lubricant prior to forming said generally tubular blank.

11. The method of claim 7, further comprising: coating said generally tubular blank with lubricant prior to forming said plurality of radially outwardly extending gear teeth.

12. The method of claim 7, further comprising: forming a plurality of radially outwardly extending splines on at least a portion of said outer surface.

13. The method of claim 7, further comprising: forming at least one hole operable to communicate fluid between said inner surface and said outer surface.

14. The method of claim 12 further comprising: contouring said outer surface prior to forming said plurality of radially outwardly extending splines.

15. The method of claim 7 further comprising: heat treating at least a portion of the gear member.

16. A method of forming an input sun gear member for an automatically shiftable vehicular transmission, the method comprising: forming a generally tubular blank by reverse extrusion of a generally cylindrical slug, wherein said generally tubular blank has an inner surface and an outer surface;annealing said generally tubular blank;forming a plurality of radially inwardly extending splines on at least a portion of said inner surface by cold extrusion; andforming a plurality of radially outwardly extending gear teeth on at least a portion of said outer surface by cold extrusion to form the input sun gear member.

17. The method of claim 16, further comprising: coating said generally cylindrical slug with a phosphate based coating prior to forming said generally tubular blank.

18. The method of claim 16, further comprising: coating said generally tubular blank with a phosphate based coating prior to forming said plurality of radially outwardly extending gear teeth.

19. The method of claim 16, further comprising: forming a plurality of radially outwardly extending splines on at least a portion of said outer surface by broaching.

20. The method of claim 8 further comprising: heat treating at least a portion of the input sun gear member.