| 摘要 |
PURPOSE:To improve the deflection accuracy of a rim by executing initial forming by approaching both forming rolls at a very low speed, and subsequently, approaching both the forming rolls at a high speed. CONSTITUTION:When a work 22 is installed onto a bottom roll 9, a servovalve 30 is operated by a signal of an electronic control unit 35, and the hydraulic pressure is supplied to a cylinder chamber 14a. Therefore, the roll 9 rises at a high speed, and when the work 22 contacts an upper roll 8, it is decelerated to a very low speed of 0-10mm./sec by a signal of a potentiometer 34. The roll 9 which is rising at a very low speed executes initial forming of the work 22 between the roll 8 and itself. Subsequently, the regular forming is executed by controlling the valve 30 and accelerating the rising speed of the roll 9. According to this method, the centering accuracy of the work is raised, and accordingly, the deflection accuracy of a rim is improved. |
