1问题的提出装载机上框架类零件如到车架支承架其上两孔的同轴度要求很高。如果其同轴度超差，造成此类零件及销轴偏磨，则会降低其使用寿命，严重影响产品的质量。因此这类零件的同轴度在加工过程中必须设法加以保证。2加工方法下面以副车架支承架为例（如图1），介绍几种框架 1 The question put forward on the loader frame parts such as the frame to the frame on the two holes on the coaxial requirements are high. If its coaxial over tolerance, resulting in partial wear of such parts and pin, it will reduce the service life, seriously affecting the quality of the product. Therefore, the concentricity of such parts in the processing must try to be guaranteed. 2 processing methods below the subframe support frame as an example (Figure 1), describes several frameworks