Analysis On Roundness Deviation And Fixture Optimization For Turning Flywheel Housing

The flywheel shell is a kind of thin-walled part with irregular shape.Under some external forces,it is easy to produce deformation during machining it,which causes roundness to be out of tolerance.When machining a flywheel housing made of aluminum,the cutting speed is too low that cause the efficiency waste of both machine tool and cutting tool.However increasing the cutting speed results in an excessive roundness of the housing circle and oil seal hole.The reasons of the roundness deviation are studied by considering clamping force,cutting force,cutting heat,fixture balance and machine tool spindle's accuracy,and optimization method is proposed.The finite element analysis method was used to analyze the deformation and its distribution of the workpiece under the clamping force.It was found that the clamping force exerted by the CTU04-L clamping cylinder on the end face of housing circle caused the deformation of the housing circle,and with the spindle rotation speed increasing,the rotating centrifugal force increases,and the overall deformation degree and area of the workpiece also gradually increases.The turning forces during the machining of the two round holes were calculated by the FEM software,and compared with the calculation results by using the empirical formula.It was found that the turning force is small and has almost no change with the increase of the rotating speed;the workpiece temperature was measured by infrared thermal imaging method when turning the workpiece,and it was not high,so that these two factors have little effect on the deformation of the part.The eccentricity between the mass center of the fixture and the workpiece system and the rotation center was analyzed.The result shows there is eccentricity in the system.The high spindle speed cause the spindle rotation runout and the wearing out of the spindle components of the machine tool.The spindle part of the machine tool was disassembled and spindle runout was measured on key positions.The result shows that the radial runout of the spindle exceeds the allowable value of the machine tool maintenance manual.Therefore,the accuracy of the spindle of the machine tool is an important factor resulting in the excessive roundness.Summing up all the above factors,deformation of the workpiece was decreased through removing out the CTU04-L clamping cylinder.The dynamic balance was improved by adding weights to eliminate the unbalanced movement of the fixture.After replacing the spindle components,the problem that roundness of the flywheel housing exceeds tolerance with the spindle speed increasing is successfully solved.