小电流钨极氩弧焊熔池表面高度测量投影系统

Molten pool surface height measurement projection system of small current tungsten electrode argon arc welding

利用傅里叶变换轮廓术的基本原理测量小电流钨极氩弧焊熔池表面高度,需要获得数量足够,调制度好的熔池变形光栅条纹。钨极氩弧焊熔池面积小,液态金属表面反射性能复杂,有强烈电弧光干扰,要综合考虑光栅节距、熔池表面反射、弧光干扰与光学系统参数之间的关系,设计好投影系统。研究表明,小电流钨极氩弧焊熔池振荡造成液态金属表面各微面元法线方向动态变化,对光束有散射效应,对于投射的结构光束,可以通过随机表面散射的镜面反射光拍摄熔池图像。将节距为0.4mm的矩形光栅以30°左右的掠射角离焦投射到钨极氩弧焊熔池表面,可获得较好的熔池变形光栅条纹,经后续处理,可初步测量出熔池表面高度。

The molten pool deformed grating stripe with enough quantity and good modulation degree was demand when we measured the molten pool surface by Fourier transform profilometry.The area of tung-sten electrode argon arc welding molten pool is small and reflecting property of liquid metal surface is com-plexity that company with strong electric arc interference.The proj ection system with good performance had designed by the overall consideration about the relationship of grating pitch,molten pool surface reflec-tion,arc interference and optical system parameters.Our study had demonstrated that the molten pool con-cussion had caused the dynamic change of normal direction of liquid metal tiny surface element that has the scattering effect on light beam.Therefore,the molten pool images can be captured by use of surface scatter-ing randomly of specular reflection light.The rectangular raster with pitch of 0.4 mm had projected on welding pool surface out of focus with angle of 30 degree.The obtained deformed laser stripes had pro-cessed by computer to acquire pool surface height preliminary.