Research For Rectification Of Welding Distortion Of Auto Generator Stator

As the development of motor vehicle industry, the demand for the electrical controlling installation and electro-equipment is increasing, leading to the increment of electric sources consumption. Thus it is significant to use the motor vehicle alternating generator which has small volume but large output horsepower. There are many problems existing in traditional production of generator stator iron core. For example, there is much scrap during the production of sheet steel by the press technology, and it is hard to fix during the welding process, also the economical efficiency is bad. There is a new technique that makes the stator iron core of the motor vehicle generator by the curled the steel strip with groove, instead of the punch structure with punched steel strip. The ellipticity of the stator iron core is large after welding, so it's necessary to rectify after the welding. Thus it is meaningful to study the welding distortion and post-welding rectification of the stator iron core.First of all, using the nonlinear finite element method to simulate the distortion of the stator iron core steel ring during the pressing, which gives helpful guidance to select the size of the steel core steel ring. On the other hand, The plasma arc welding method has been used due to its excellent appearance of weld bead, small welding distortion, narrow molten pool width, large penetration. Six welding guns are used simultaneously and the parameters are optimized during the welding process. The iron core steel ring is made up of multilayer steel strips before welding, there are new problems after steel strips wrapping around, such as the occurring of plastic distortion and the interior stress, and the separation of steel strip from each other. Thus it is necessary to give effective restriction before welding. At the same time, rigid project restriction is used inside the every slot to limit the large distortion of the small slots of the steel ring during the welding process. Meanwhile, special welding clamp for tiering steel ring which is fit for welding are also designed to restrict the large distortion of the outside of the steel ring. And the experimental results show that the welding clamp can control the slot distortion after welding effectively. At last, as the heat in the metal around weld bead is nonhomogeneous during the welding process, it causes the unhomogeneous transverse contraction along the thickness of the steel ring, which may lead to the angular distortion and the distortion of the roundness. The excessive rigid moulds to rectify steel ring is designed to realize distortion rectification after welding. The best roundness rectification size of mould is obtained by finite element simulation and it is used to rectify the welding distortion. After the distortion rectification, the welding distortion is reduced from 0.32mm to 0.09mm which meets the design demand of stator iron core.