| 摘要 |
PURPOSE:To enable inexpensive mass production by a simple process for manufacture by subjecting the surface of a circular columnar bar consisting of a metallic material to a coloring treatment and forming plural parallel hollow grooves in the longitudinal direction of said bar at a prescribed interval then cutting the bar to a prescribed size and mounting a revolving shaft thereto. CONSTITUTION:The fats and oils on the surface of a circular columnar bar 11 consisting of a metallic bar of brass, etc. are dissolved away. After washing, the metallic material is subjected to surface descaling and polishing and is dipped at an ordinary temp. in a rinse finish liquid intended for activation. The bar 11 after washing is dipped in a soln. compounded with 50-20g potassium sulfide, 50-80 sodium hydroxide and about 1l water to form a black film 12 of cupric oxide by chemical conversion on the surface of the bar 11. Parallel hollow grooves 13 having the same depth are machined on the circumferential surface of the bar 11 at an equal interval in the longitudinal direction thereof. Such bar is cut to a prescribed size (t) and a revolving shaft is mounted thereto. The film thickness is uniform and is dimensionally accurate. Corrosion resistance is improve. The revolution detector is thus inexpensively worked in short time. |
