Research On The Design And Manufacturing Of High Precision Arc Indexing Cam Profile Based On Bidirectional Curvature Continuity

With the rapid development of modern industry,people’s requirements for indexing cam mechanisms are constantly increasing.As the most ideal indexing cam mechanism,the curved indexing cam mechanism is widely used in various automated machinery due to its advantages of smooth operation at high speeds and high indexing accuracy.In order to meet the requirements of modern industry for high-precision and high-speed arc indexing cam mechanisms,this project conducts research on arc indexing cam mechanisms from four aspects: curve optimization of arc indexing cam,contour surface configuration of arc indexing cam,five axis CNC machining of arc indexing cam,and parameterized design of arc indexing cam.The aim is to develop better performance cam curves Following the prototype of the curved surface indexing cam surface and the higher machining accuracy of the five axis CNC machining curved surface cam program,to accelerate the localization and independent intellectual property rights of the curved surface indexing cam device.This article summarizes the motion characteristic values of 33 classic cam curves,focusing on the widely used cam curves such as harmonic trapezoidal combination curves,Fourier series curves,and polynomial curves,and summarizes the selection principles of cam curves.A design method for curved indexing cam curves is proposed based on Non Uniform Rational B-Splines(NURBS)theory.The NURBS curved indexing cam curve expression is established under six boundary conditions of the curved indexing cam.Taking the five characteristic parameters of the cam curve,including maximum speed,maximum acceleration,maximum dynamic torque,maximum jump,and maximum jump,as the objectives,an optimization model is created based on multi-objective optimization method.The curve of the curved indexing cam is multi-objective optimized with the order of the NURBS curve and control points as variables to obtain a better cam curve.A comparative analysis was conducted on the modified sine curve with the best comprehensive performance among classical cam curves,and a NURBS cam curve with better performance was obtained using the multi-objective optimization method mentioned above.According to the theory of space conjugate surface,the equation of globoidal indexing cam contour surface is derived by using homogeneous coordinates transformation method.Propose an adaptive configuration method for the curvature of the curved surface of a curved cam profile.Based on the multi-objective optimization of the NURBS cam curve,perform the UV bidirectional curve cluster configuration of the curved surface of a curved indexing cam profile.The U-shaped curve and V-shaped curve represent the trajectory line and conjugate contact line of the contact point between the cam and the roller,respectively.The curvature adaptive spacing is measured using the first curve in the V-shaped direction,and the obtained spacing is used as the spacing between the U-shaped curve clusters.The V-shaped curve clusters are configured in the same way.Import the constructed curve clusters into NX software in an appropriate manner and generate cam profiles to achieve 3D modeling of curved indexing cams.A comparison was made between equivalent machining and non equivalent machining methods for curved indexing cams,and the non equivalent machining free surface method was ultimately used for five axis CNC machining of curved indexing cams.Based on the GROB five axis machining center,the machining process of the curved indexing cam was analyzed,and the numerical calculation of the tool path trajectory of the curved indexing cam contour surface was studied.The tool path trajectory was obtained by approximating the contour curve with equal parameter linear segments,and the tool path simulation was conducted.In order to further study the multi axis CNC machining of curved cams,the tool path trajectory of curved indexing cam machining was generated based on the 3D software CAM machining module,and the post processor of the GROB five axis machining center was customized to generate numerical control(NC)machining codes.Due to the fact that the actual design of curved indexing cam mechanisms often requires repeated writing due to different design parameters.Therefore,based on NX,a parameterized design system for curved indexing cam mechanisms is developed,which automatically realizes cam curve design,profile equation expression,cam solid modeling,and CNC machining in C++environment.The system has a good user interaction interface.By inputting the design parameters of the arc indexing mechanism,the system can automatically complete the three-dimensional modeling of the arc indexing cam mechanism,and can perform multi-axis CNC machining of the arc indexing cam mechanism according to user needs,improving the design efficiency of the arc indexing cam mechanism.