| With the strong holding force of the bronze-bond and the excellent grindingperformance of the diamond-abrasive, the bronze-bonded diamond wheels have awide application prospect in the field of engineering ceramics, optical glass,ultra-precision grinding and difficult-to-cut material grinding. However, because ofthe ultrahigh hardness of the diamond-abrasive, the truing and dressing process of thebronze-bonded diamond wheel is very difficult, which really affects the full exertionof the grinding performance of the bronze-bonded diamond wheel to a certain extent.In this paper, from both numerical simulation and experimental investigation, muchresearch work has been done on on-line truing and dressing bronze-bonded diamondgrinding wheel by acoustic-optic Q-switched YAG pulsed laser which is based onthermal effect.First of all, by measuring the pulse widths and laser powers of acoustic-opticQ-switched YAG pulsed laser, the laser power densities are calculated. The laserpower density-thresholds are obtained on laser dressing and shaping bronze-bondeddiamond grinding wheel in different pulse widths, by both considering the realthermal properties of the mixed bronze-bond and the graphitization of thediamond-abrasive in high temperature, and the results are verified through theexperiments and simulations. The suitable test parameters are also determined. TheEXE executable program is established for on-line truing and dressing ofbronze-bonded diamond grinding wheel with acoustic-optic Q-switched YAG pulsedlaser by means of Visual Basic software, which is used in calculating the pulse widths,the laser powers and the laser power density-thresholds under different testparameters, and also in determining the suitable test type on this test parameters.Secondly, by using ANSYS finite element method, a3-D mathematicalsimulation model and a heat transfer model of single pulsed laser ablating thediamond abrasive are established by considering the graphitization ofdiamond-abrasive on the basis of, which could show the temperature distribution ofthe diamonds under different test parameters, and they are proved to be correctthrough the experiments. The removal depths of the diamond-abrasive and the depthsof carbonize layer in different test parameters (repeat frequency and laser pumpingcurrent) have been measured, and the relationships between them have been analyzed. By virtue of simulation results, the mechanism of acoustic-optic Q-switched YAGpulsed laser truing and dressing the bronze-bond diamond grinding wheel is furtheranalyzed.Subsequently, the grinding wheel speeds range from0.42r/s to1.43r/s which aresuitable for laser on-line truing and dressing bronze-bonded diamond grinding wheelby acoustic-optic Q-switched YAG pulsed laser are obtained after theoretical analysisand calculation. The on-line grinding wheel dressing is achieved with laserdisplacement sensor based on CCD triangulation principle which is used inmonitoring the on-line circular run-out of the grinding wheel, and the Linux controlsystem based on ARM embedded system which is used in control of the Q-switch andthen control of the output of the pulsed laser. After laser on-line truing and dressing,the accuracy is further improved, the circular run-out error is reduced to20μm, andthe surface topography is improved too．Finally, the bronzed-bond diamond wheels dressed by pulsed laser are put togrind the specimens, which are made of YT5cemented carbide. The feasibility andsuperiority of on-line truing and dressing of grinding wheel by YAG pulsed laser areverified by measuring the grinding force ratio and the surface roughness of workpiece compared with the mechanical method, and the influence degree between testparameters(repeat frequency and laser pumping current) and the grinding quality arecalculated by using Grey Relational Analysis and orthogonal grinding experimentwhich will help us to select optimal parameters. |
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