Research On Precision Turning About MMicrowave Cavity Modulation Structure

Terahertz microwave devices are widely used in the field of communication, detection and medical, with the increasingly higher requirements of power, efficiency and frequency band, the machining accuracy of microwave devices need to improve accordingly. Conventional microwave devices processing technology gradually cannot satisfy the accuracy requirement, especially the slow wave structure which is the core components of microwave devices, higher precision machining technology should be proposed.For the sine cavity slow wave structure, which has high depth-to-width ratio, is difficult to obtain high-accuracy. Therefore, this paper researches on the precision SPDT turning technology of the microwave cavity modulation structure to meet the accuracy requirements.Considering the high value peak valley from of sine structure, this paper makes the multilayer trajectory planning for it. Using the method of equal chord height to optimize the way of generating discrete points, which can improve machining efficiency, in the linear interpolation model. In addition, this paper studies the spline interpolation processing mode and put forward three uniform B-spline interpolation arithmetic for trajectory planning, and it has higher approximation accuracy than the linear interpolation model. Furthermore, the radius compensation has been used to optimize the trajectory planning of sine structure.In order to decrease the deformation and improve processing efficiency at the same time, this paper established the three-dimensional finite element model of OFHC copper using the ABAQUS software to study the influence of process parameters on cutting force and cutting heat. Then the deformation finite element simulation model is established based on the cutting force and cutting heat. The birth-death element technology and moving load application technology can simulate the deformation of work-piece. Then we can selection process parameters for actual cutting based on the deformation simulation result.In the experiment, this paper uses ultra-precision diamond lathe to finish the precision machining of microwave cavity modulation structure and detects the surface figure accuracy by Taylor Hobson profiler. Compared with the result of interpolation and spline interpolation mode, the superiority of spline interpolation on the machining accuracy proves to be true. Furthermore, this paper analyses the influence of cutting process parameters on the machining accuracy. Finally the paper analyses the major factors that influence the surface accuracy during processing and proposes improvement measures.