Experimental Research On The Influence Of Process Parameters Of The Power Spinning Connecting Rod Bushing On The Dimensional Precision And The Residual Stress

The connecting rod bushing is an important connecting part of crank connecting rod mechanism of diesel engine,which bears the inertia force of the connecting rod and the pressure of the cylinder. The power spinning connecting rod bushing has the advantages of non cutting process,good surface quality, improved material properties and utilization,which has been widely used in transportation, military, medical, aerospace and other fields. It may lead to product deformation, uncertain accuracy and even the connecting rod bushing fatigue failure.The influence of the main process parameters on the dimensional accuracy and the residual stress of the workpiece is studied, which has profound significance to the production and use of the connecting rod bushing.Residual stress detection methods used in engineering include small Kong Fa, X ray method, ultrasonic method and so on.Compared with other methods, X-ray detection method has the advantages of high sensitivity, good accuracy and strong operability. So it is regarded as a recognized and mature nondestructive testing method. This experiment adopts X-ray method to detect the residual stress of bushing. The tin bronze(QSn7-0.2) material connecting rod bushing manufactured through power spinning process is used as the research object. Through using the method of single factor experiment, The connecting rod bushing after the process of power spinning and heat treatment was tested.The inner diameter expansion of bushing, the wall thickness deviation and the residual stress of different layers are measured. Through analyzing the test results, the influe nce of thinning rate, first round reduction and feed ratio on diameter expansion, wall thickness deviation, residual stress is obtained,and The influence of Annealing on the residual stress of connecting rod bushing is also obtained. Though optimizing processing technology, the optimal combination of process parameters is thinning rate of 35%-25%, he first round of reduction of 0.5t, feed ratio of 0.6mm/r, heat treatment temperature of 280 ℃, holding time of 2 hours.