弧焊环拉深划伤机理及其防止技术的研究

Investigation on scratching mechanism of arc-welding ring and technology preventing from its scratching

对 1Cr18Ni9Ti不锈钢弧焊环圆筒形冲压件拉深过程中划伤产生的机理进行了分析 ,明确指出弧焊环拉深时产生划伤是由 7个方面的因素造成的。产生拉深划伤必须满足坯料表面存在局部凸起 ,在高温和高压下坯料和模具之间产生粘合 ,粘合点被拉开后在模具上形成牢固的粘结瘤 ,粘结瘤的硬度明显高于拉深坯料的表面硬度 4个条件。为防止该件拉深时划伤现象的发生 ,则在拉深时应采用良好的润滑剂、提高模具表面的光洁度、适当降低压应力、增大凹模圆角半径、工件及模具表面保持干净、板料的材质应符合要求 (特别使其塑性异性小 )、镍及钛元素含量足够、退火软化完善合格、中间过渡工序的筒形件口部带有圆角的小法兰、及时消除模具上的粘结瘤、将原工艺的 5次拉深改为 3次拉深或 2次变薄旋压。

The scratching mechanism of arc-welding hoop of circular cup stamping part made from 1Cr18Ni9Ti stainless steel in the course of its drawing is analyzed. It is definitely pointed out that the scratching of the arc\|welding hoop in the course of its drawing results from seven factors. Drawing scratching happens when four conditions are satisfied,which are that local heave exists on the blank surface, adherence between the blank and the die under high temperature and high pressure is produced, hard adherence burl is formed when the adherence is departed, and the hardness of the adherence burls are more higher than that of the blank surface. In order to prevent from the scratching phenomena, the following measures are introduced, such as using fine lubricant, increasing the finish of die surface, reasonably decreasing the compression stress in tangent direction of flange, increasing the concave die radius of rounded corner, keeping the surface of piece and die clear, making the material of the blank correct, especially making plastic isomerism of the blank material as low as possible, making nickel and titanium element's content enough, keeping anneal intenerating better, letting the mouth end of circular cup part of midst working procedure have a small flange with a rounded corner, eliminating the adherence burls on the die in time, changing the five times drawing of previous technology to thrice drawing and twice thinning spinning. The above measures are successfully used in practice.