小直径厚壁高频焊管成型孔型改进

形成高频焊管成型缝壁厚V形口的根本原因是:变形管坯对接边边缘存在不可避免的变形盲区，且管壁越厚，管径越小，壁厚V形口越明显，对焊缝强度的负面影响越大。因此，小直径厚壁管的变形盲区相对更宽，造成管坯边缘成型质量不良，对焊缝强度的负面影响非常显著。采用边缘双半径孔型设计能够在变形盲区存在的情况下，实现待焊管坯对接面平行对接，通过变形工艺的改进，保证了小直径厚壁管的焊缝强度。

Pass Improvement for High Frequency Welded(HFW) Pipe with Small Diameter and Thick Wall

The original reason of generating V notch of HFW pipe with longitudinal weld lies in：unavoidable deformation blind area exists in butt edge welding of deformed pipe blank,the heavier of pipe wall is,the smaller of pipe diameter is,and the shape of V notch is more obvious,the greater negative effect on weld strength.So the deformation blind area of small diameter and thick wall welded pipe is relative wider;this will cause to bad forming quality of pipe blank edge,and obvious negative effect on weld strength.It pointed out that under existing blind area,adopting double radius pass on pipe edge design can realize parallel butt welding of pipe blank which will be welded,through improving deformation process,weld strength of small diameter and thick wall welded pipe can be ensured.