Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4810287 | Process for producing steel for valve springs | Tsutomu Saka, Yukio Ito | 1989-03-07 |
| 4795609 | High-strength steel for valve springs, process for producing the steel, and valve springs made of the same | Tsutomu Saka, Yukio Ito | 1989-01-03 |