Research And System Development Of Post-Processing Technology For 5-Axis Denture CNC Machines

With the improvement of people’s living standard,the demand for oral health is getting higher and higher,and the demand for denture is also increasing.However,the existing denture machining equipment has a low level of localization,and foreign denture machining equipment is expensive and untimely in service.It is necessary to develop a denture CNC(Computer Numerical Control)machining system with independent intellectual property rights.Post-processing technology is one of the core technologies of the denture CNC machining system.This technology undertakes the task of converting the tool position file data generated by the computer-aided manufacturing(CAM)system into a CNC code that can be recognized by the CNC machine.Post-processing technology plays an important role in improving the accuracy of the denture CNC machining.To this purpose,five-axis denture CNC machining post-processing techniques are investigated in this thesis,and denture machining post-processing systems are designed and developed.In order to solve the problem of non-orthogonality of the rotary axis of the double rotary table machine tool in denture machining,the A-C double rotary table type five-axis CNC machine is used as an example in this thesis,and its motion mechanism is analyzed,and the kinematic model of the A-C double rotary table five-axis machine is developed,and the coordinate transformation equation with offset compensation is derived using the principle of flush coordinate transformation.Non-linear motion errors are inevitable in the post-processing process of 5-axis denture CNC machines.In order to effectively reduce such errors,a nonlinear error control strategy that improves the adaptive linearization method is designed in this thesis.According to the nonlinear error generated by any two adjacent tool points,the nonlinear error is calculated by using interpolation algorithm,kinematic forward transformation and vector fork multiplication method.It is verified that the maximum nonlinear error generation position is located near the midpoint of the two tooling points.The error compensation function is used to obtain the error value and compare it with the maximum permissible error to determine the new inserted tooling point,so as to realize the nonlinear motion error compensation.The effectiveness of the strategy is verified by MATLAB simulation.The problem of acceleration and deceleration control of feed rate is further studied in this thesis in order to ensure smooth change of feed rate of denture CNC machine.A smooth control strategy for feed speed between continuous line segments in denture 5-axis linkage is designed.In order to make the feed speed at the transition angle change smoothly,the size of the transition angle between consecutive line segments is calculated,the constraints of the feed speed at the transition angle are analyzed.The theoretical analysis is performed in conjunction with the S-curve acceleration and deceleration method,and the feed rate between successive line segments is corrected and controlled for acceleration and deceleration.The method is implemented by MATLAB programming,and the effectiveness of the method is verified.Based on the above theoretical research,a denture CNC machining post-processing software system is designed and developed for the actual needs of a denture machining enterprise in this thesis.The overall software architecture and software interface layered structure are designed.Based on C++ programming language,the post-processing algorithm is applied under Qt Creator platform environment,and the development of the main functions such as IO file operation and code conversion of the system is initially realized.