| 摘要 |
PURPOSE:To obtain spring steel which is increased in strength by tempering the spring steel which is subjected to a hardening treatment in a prescribed temp. range, tempering the same in the temp. region where the change in the 3rd stage arises or the temp. below said region and subjecting the steel to shot peening simultaneously in the tempering process. CONSTITUTION:Electricity is conducted through electrodes 2, 3 to the spring steel A which is subjected beforehand to coiling and a hardening treatment to heat the steel quickly in a short time, for example, for about 30sec, and the steel is tempered at the temp. at which the change in the 3rd stage of the tempering arises or the temp. below said temp. The temp. in this case is <=350 deg.C, more preferably about 200-250 deg.C with middle carbon steel. The heating speed, heating temp., holding time, etc. in this stage are controlled with a computer 3 for control in accordance with the surface temp. of the steel A while aid temp. is detected with a temp. measuring device 4. Shot peening devices 5, 5 are operated simultaneously in the above-described tempering stage to apply warm peening to the steel with the prescribed coverage, arc height and projection time controlled with the computer 3, whereby the intended spring steel is obtained. |
