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针对波纹管现有制造工艺存在焊缝多、周期长、成本高、焊缝区易出现扩展裂纹等缺陷,提出采用无芯模缩颈旋压成形波纹管,并基于ABAQUS/Explicit平台建立了波纹管无芯模缩径旋压的三维弹塑性有限元模型。分析波纹管缩径旋压过程中的应力应变分布规律表明,直壁区与斜壁区相交处的圆角是应力和塑性应变集中区,该圆角区域在旋压过程中易产生厚向过度减薄和拉裂。采用单因素实验设计方法获得了工艺参数对成形质量的影响显著性和影响规律,并实验验证了数值模型结果的可靠性和实用性。结果表明,芯模转速对成形质量影响最大,芯模转速增大时,工件直壁区径向尺寸与波纹中心高度的精度均会变差;旋轮圆角半径对成形质量有一定的影响,较小的旋轮圆角半径无法使材料完全达到塑性状态而产生较大回弹,最终导致较大的几何尺寸精度偏差;而较大的旋轮进给速度容易在旋轮前方产生金属堆积,易使已旋区发生过度减薄从而影响成形质量。
According to the existing manufacturing process of corrugated pipe, there are many defects, such as many welds, long period, high cost and easy expansion crack in the weld zone. It is proposed that the corrugated pipe is formed by coreless die neck spinning, and the corrugation is established based on the ABAQUS / Explicit platform Three Dimensional Elastic - Plastic Finite Element Model of Tube - Spherical Diameter Spinning. The analysis of the stress and strain distribution during the process of reducing the diameter of the bellows shows that the fillet at the intersection of the straight wall area and the inclined wall area is the stress concentration and plastic strain concentration area, which is prone to over-thickness during the spinning process Thinning and cracking. The influence of process parameters on forming quality was obtained by single factor experimental design method, and the reliability and practicability of the numerical model were experimentally verified. The results show that the rotational speed of the mandrel has the greatest influence on the forming quality. When the mandrel speed increases, the accuracy of the radial dimension of the straight wall of the workpiece and the height of the corrugation center will be deteriorated. The fillet radius of the mandrel has a certain influence on the forming quality, The smaller radius of the roller can not make the material completely reach the plastic state and produce a greater rebound, which eventually leads to a larger deviation of the geometric accuracy; and the larger roller feed speed tends to produce metal accumulation in front of the roller, It is easy to make the spinning area reduce excessively to affect the forming quality.