过去,我国汽车拖拉机轮圈生产采用立式冷滚压、热滚压和扩张模热挤压法。这种立式滚压机生产的轮圈精度低,内径公差不易保证,椭圆度大,易出现喇叭口形状,变薄不均,跑边严重。生产率低,需经过两三道工序(尤其前轮圈),即两三套模具才能成形。扩 In the past, China’s automobile tractor wheel rim production using vertical cold rolling, hot rolling and expansion die hot extrusion method. This vertical roller production of low-precision rims, diameter tolerance is not easy to ensure large ovality, easy to appear bell mouth shape, uneven uneven, serious running. Low productivity, through two or three processes (especially the front rim), that is, two or three sets of molds can be formed. Expand