金属板件等离子体弧柔性成形技术基础研究

Basic research on flexible forming of sheet metal using plasma arc

水火弯曲成形和激光弯曲成形均存在一定局限性,而等离子体弧具有平均能量转换效率高、成本较低等优点.介绍了等离子体弧柔性成形技术的原理和特点,分析了等离子体弧柔性成形的两种基本形式——正向弯曲和反向弯曲的成形机理和控制方法,研究了弧功率、扫描速度、冷却方式、板件材质与几何尺寸等因素对柔性成形的影响规律.研究结果表明:等离子体弧可在工业环境下完成对不同厚度板材的柔性成形.在一定范围内,弯曲速度随着弧功率的提高而提高;可运用小的扫描速度提高弯曲速度,而采用大的扫描速度实现较为精确的弯曲变形;随着板件厚度的增加,相同扫描次数下的弯曲角度明显减小;导热系数大的材质,因难以在材料内部形成大的温度梯度而难以产生弯曲变形.上述研究对合理选择成形参数具有一定的指导意义.

Both oxyacetylene line heating forming (OLHF) and laser bending forming (LBF) have some defects, but plasma arc has higher average energy conversion factor, lower operation cost and some other advantages. The mechanism and features of flexible forming using plasma arc (FFUPA) are introduced. Two basic forms of the FFUPA, bending towards and away from plasma arc, are analyzed. The influence of arc power, scanning speed, cooling conditions, sheet materials and the sample size on the bending angle has been investigated through experiments. The experimental results show that the plasma arc can be used to form different thickness sheet metal in industrial environment; the bending angle is sharply enlarged with the arc power increasing; the lower scanning speed can be used to improve the forming speed, while higher scanning speed can be used in precision forming; the bending angle is sharply decreased under the same scanning times when the thickness of sheet metal increases; the forming of sheet metal with larger coefficient of heat conductivity is more difficult because the temperature gradient through the sheet thickness is small. This study is of instructive significance in selecting forming parameters reasonably.