Natural Diamond Tool Grinding Process Monitoring Technology

Natural diamond cutting tool occupies an important position in precision and ultra-precision processing technology for its very sharp cutting edge. However, many factors affect the grinding quality of the cutting tool. Analyze the signals produced by cutting tool grinding process is helpful to study the influence of each factor upon grinding quality of cutting tool, to provide technical support for the further precision grinding, which is of great significance to stabilize the grinding quality of cutting tool. In this thesis, firstly the key technological conditions affecting diamond cutting tool are analyzed, the performances of present grinding machine and surrounding environment characteristics are also summarized. Monitoring system composed of signal acquisition module, image acquisition module, data acquisition module and computer based on existent machine tool to monitor vibration, sound and force signals of diamond cutting tool grinding process is constructed.Corresponding data procedures based on Matlab software is compiled, signal processing methods of wavelet packet decomposition and spectrum analysis are applied to analyze sensitivity of acquired vibration, sound and force signals in the monitoring system towards diamond cutting tool grinding process. The test results show that vibration signal is most sensitive towards diamond cutting tool grinding process, which is most suitable for monitoring the grinding process in the three.Grinding direction has a great impact on grinding quality and efficiency, traditional orientation methods can not meet the requirement of production efficiency of cutting tool, meanwhile, there are no suitable equipments to carry out crystal orientation accurately because of restriction of test conditions. Therefore, diamond cutting tool is grinded on different directions, vibration signals produced by diamond cutting tool grinding are monitored, and power spectral density and RMS are calculated, then fitting curve slopes of calculated results are contrasted to compare the cutting tool grinding efficiencies on different directions. Test results show that this method can preliminarily determine the grinding directions of diamond cutting tool, thus provide a new way for crystal orientation of diamond cutting tool.Control of feed has a significant impact on grinding quality of diamond cutting tool, the lack of feed resolution of present machine tool can not meet the requirement of tiny feed grinding. Hence the feed subdivision test is designed, the grinding vibration signals on each subdivided feed are monitored and analyzed. Test results show that eigenvalue of vibration signals can be used to characterize the actual grinding feed. According to existent condition, it is available to the grinding quality of the cutting tool when the grinding feed is optimized to about 10μm.The timing of draw back of cutting tool plays an important role in ultimate quality of cutting tool, so a good cutting tool is grinded, then makes damage on that tool in the case of keeping it clamped, vibration signals of the two are both monitored, the data are contrasted and analyzed by rational division of small frequency band. Test results show that vibration energy will increase when cutting tool breaks down during the grinding process, and in high frequency band, the energy amplitude nearly doubled. This result offers theoretical basis for the determination of the timing of draw back of cutting tool.