Research On Optimization Of Four Axis Interference Free Tool Path And Constant Cutting Force Machining For Complex Screw

The screw rotor is the core component of a screw compressor,and the accuracy of the screw determines the sealing and aerodynamic performance of the compressor.The screw structure is complex and the tooth surface is twisted greatly.In order to improve the machining efficiency and stability of the screw,this article studies the optimization of the interference free tool path for rough machining of the screw and the constant cutting force problem for precision machining.In order to improve the efficiency of rough machining,according to the screw rotor structure,a machining strategy of equal depth hierarchical milling is adopted,and a method to accurately determine the boundary of rough machining area is proposed.On this basis,the tool contact path and interference free tool axis range of rough machining are planned.Based on the equal residual height method,the machining line spacing is calculated,and the factors affecting the line spacing are analyzed.Based on this,the optimal tool direction is planned.Combined with the machining tolerance requirements,the inclination angle of the rough machining tool is optimized.Finally,the tool path trajectory is generated based on the non-interference tool contact trajectory.To address the issue of stability in precision machining,a milling force model for ball end milling cutters is first established.Considering the surface characteristics of the screw tooth surface,different curvature radii have a significant impact on the cutting force.Based on the actual machining of the screw,the milling force model is improved and can predict the changes in milling force in different regions of the machining process.By utilizing the relationship between milling force and feed rate,with milling force as the constraint objective,a constant cutting force algorithm is proposed to optimize the value of feed rate and maintain the stability of cutting force.Finally,a four axis machining experiment was conducted on the screw,and the feasibility of the constant cutting force algorithm was verified through milling force comparison.The machining surface was measured to verify the machining accuracy.