Polishing Equipment Design Of The CVD Diamond-coated Drawing Dies And Polishing Technology Study

The diamond coatings obtained by chemical vapor deposition have rough surface and poor precision,which can't meet the drawing industry's requirements.Therefore,it is an indispensable step to polish the CVD diamond-coated drawing dies.Tribochemcial polishing technology is based on diamond graphitization theory,with a high removal rate and simple equipment,etc.So,its application prospect is broad.In this paper,based on the theory of diamond graphitization and micro-cutting,tribochemcial polishing technology and mechanical grinding technology were used to rough and fine-work the CVD diamond-coated drawing dies for high efficiency and low damage polishing.The main research contents are as follows:(1)On the base of the deep understanding of the polishing principle,the polishing equipment was designed by the modular design ideas,including scheme design,mechanical structure design,control circuit design.Through the selecting,machining,assembling and other follow-up process,the polishing equipment which is used to polish the CVD diamond-coated drawing dies,was developed successfully.(2)This paper aims at solving the problems like high wear rate of polishing plate(rod)and low material removal rate efficiency in tribochemcial polishing.Based on the diamond graphitization theory and polishing plate(rod)material requirements,five kinds of new alloy polished rods,such as MnCuNi,were successfully made by using mechanical alloying and hot-pressure sintering.And their structure and mechanical properties were analyzed.(3)The self-made alloy rods were used for the tribochemcial polishing test.The results showed that: for the diamond removal rate and its own wear rate,all the alloy polishing rods were different.The polishing performance of MnCuNi alloy rod was the best,the removal rate was 1.58mg/h,and its wear rate was the lowest,namely 3.37mg/min.At the same time,under certain conditions for diamond polishing experiments of using MnCuNi alloy rod and electroplated diamond grinding head,the results showed that the dynamic friction polishing technology was superior to traditional mechanical polishing in terms of removal rate,wear rate and cost-effective.(4)We employ rough-polishing and fine-polishing to test CVD diamond coatings with large bore drawing dies,MnCuNi alloy polishing rods for the rough-polishing,electroplated diamond polishing head for the fine-polishing.The research showed: In a certain range of parameters,the removal rate of diamond increased with the increase of velocity and pressure,and the surface roughness decreased first and then increased,therefore,the optimal linear velocity and pressure exist.In this paper,by using the optimal polishing process(0.5h of rough-polishing,1.5h of fine-polishing),the diamond coating's surface roughness can reach to 0.075?m.