科研之友
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摘要
Servo presses driven by AC servo motors, developed in the last decade, are spreading very fast in Japan. Because of their flexible motions, they are expected to change the technology of metal forming, similarly to the CNC metal cutting machine tools. In this review, the effects of servo presses are explained from the viewpoint of the type of press motion. When the ram retreats in the stepwise or oscillating motion, the work-piece surface is re-lubricated by liquid lubricant, preventing fracture and wrinkling in deep drawing and lowering the load in cold forging. It is also possible to reduce the noise and burr in shearing of sheet by changing the punch velocity in processing. Together with the heated tools or electric heating devices, it is possible to raise the work-piece temperature within a stroke of forming. Using the servo presses with two or more moving axes, it is possible to extend the limiting drawing ratio in deep drawing by changing the blank holding force, and to reduce the punch pressure in enclosed die forging by driving the container. By combining with hydraulic systems, the extruded lengths from multiple exit holes are equalized, and fracture is prevented in piercing and cold forging of magnesium alloys.
- 出版日期2010-9
