汽车排气管氧传感器螺母焊接变形的成因分析

采用实验方法分析了汽车排气管氧传感器螺母焊接变形的成因及对策.通过红外热像仪获得螺母焊缝最高温度,计算对应于该最高温度的螺母最大变形量;用量具测量获得螺母焊接后的实际最大变形量.比较由红外热像仪和量具获得的螺母最大变形量后发现,两者数值相同,且焊后螺母直径缩小、壁厚增大,越接近焊缝处其直径越小、壁厚越大.因此焊缝高温是导致螺母焊后变形的重要因素,建议降低螺纹精度以弥补焊接热变形.

Analysis of Causes for Deformation at Screw Nut of Oxygen Sensor of Automobile Exhaust Pipe when Being Welded

Test method is adopted to analyze the reasons for and solutions to deformation of screw nut of oxygen sensor of the automobile exhaust pipe when being welded.The highest temperature at weld-gap of screw nut is obtained by using infrared cameras.The maximum deformation corresponding to the highest temperature is calculated,the actual maximum deformation of screw nut after welding corresponding to the highest temperature is calculated using a measuring tool.The comparison between the maximum deformation of screw nut obtained by using infrared thermography and that by a measuring tool shows that the two values are the same,the diameter of screw nut decreases,and the wall is thicker.And the closer to weld-gap,the shorter is the diameter and the thicker is the wall.Therefore,high temperature of weld-gap contributes to the screw deformation after being welded.This paper thus suggests that accuracy of screw thread be reduced so as to remedy heat deformation of welding.