Claims
- 1. A method for manufacturing a hollow rack shaft comprising:a first step for forming a substantially flat and rectangular plate workpiece into a gutter-like shaped workpiece, said gutter-like shaped workpiece having a flat bottom portion, a pair of semi-circular bottom portions extending from each longitudinal side of said flat bottom portion, and a pair of leg-like side walls extending upwardly in parallel from each lateral side of said flat bottom portion and said semi-circular portions; a second step for forming a row of rack teeth on said flat bottom portion of said gutter-shaped workpiece; and a third step for forming said workpiece into a hollow shape by bending said leg-like side walls by butting edges of said walls to each other; wherein a surface of a die set used in said second step is provided with a plurality of recesses provided at respective tooth-forming parts of said surface for releasing surplus material of said workpiece in a die clearance at a stroke end of press-forming.
- 2. A die set used in a method for manufacturing a hollow rack shaft, said method comprising:a first step for forming a substantially flat and rectangular plate workpiece into a gutter-like shaped workpiece, said gutter-like shaped workpiece having a flat bottom portion, a pair of semi-circular bottom portions extending from each longitudinal side of said flat bottom portion, and a pair of leg-like side walls extending upwardly in parallel from each lateral side of said flat bottom portion and said semi-circular portions; a second step for forming a row of rack teeth on said flat bottom portion of said gutter-shaped workpiece; and a third step for forming said workpiece into a hollow shape by bending said leg-like side walls by butting edges of said walls to each other; wherein a surface of said die set used in said second step is provided with a plurality of recesses provided at respective tooth-forming parts of said surface for releasing surplus material of said workpiece in a die clearance at a stroke end of press-forming.
- 3. A die set according to claim 2, wherein each die of said die set is divided into a plurality of segments at said recesses.
- 4. A die set according to claim 3, wherein said recess is located at a position where a protrusion formed by said recess does not interfere with a pinion engaged with said rack.
- 5. A die set according to claim 2, wherein said recess is located at a position where a protrusion formed by said recess does not interfere with a pinion engaged with said rack.
Priority Claims (3)
Number |
Date |
Country |
Kind |
2000-064298 |
Mar 2000 |
JP |
|
2000-114306 |
Apr 2000 |
JP |
|
2000-114502 |
Apr 2000 |
JP |
|
Parent Case Info
This application is a divisional of co-pending Application Ser. No. 09/803,560, filed Mar. 9, 2001, the contents of which are hereby incorporated by reference.
US Referenced Citations (23)
Foreign Referenced Citations (9)
Number |
Date |
Country |
2026908 |
Feb 1980 |
GB |
2056894 |
Mar 1981 |
GB |
2061138 |
May 1981 |
GB |
2108026 |
May 1983 |
GB |
58-218339 |
Dec 1983 |
JP |
05-345231 |
Dec 1993 |
JP |
06-246379 |
Sep 1994 |
JP |
11-180318 |
Jul 1999 |
JP |
11-278287 |
Oct 1999 |
JP |