Experimental Research On Laser Dressing Of V-Shaped Resin-Bonded Diamond Grinding Wheel

In recent years,superabrasive（diamond,CBN）grinding wheel grinding technology is an important means of processing complex surface parts of hard and brittle materials such as engineering ceramics and optical glass.V-shaped resin-bonded diamond grinding wheel is a kind of superabrasive tool prepared with diamond as abrasive grain and resin as bond.It can be widely used for micro-grooves,micro-array grinding of functional substrates of various materials such as ceramics,single crystal silicon and optical glass.Although this type of abrasive tool has excellent wear resistance,in grinding process,the working surface of the grinding wheel will inevitably be blocked,and the tip of the grinding wheel is also easily worn.In order to improve the efficiency,precision and quality of grinding,the grinding wheel must be regularly dressed.Laser dressing technology is a kind of grinding wheel dressing method with great advantages,which can be applied to the dressing of various abrasive and bond types of grinding wheel.In this paper,aiming at realizing the high-efficiency laser dressing of V-shaped diamond grinding wheel,the research method of combining theoretical analysis and technological experiment is used to systematically carry out the research on laser profiling and sharpening of V-shaped resin bonded diamond grinding wheel.The specific contents are as follows:1)An experimental platform for laser dressing of formed grinding wheel was built.By establishing the spatial relationship between laser beam and grinding wheel contour during profiling,the variation law of laser irradiation power density with the length of scanning trajectory was calculated and clarified.Using the spectrometer to assist in monitoring the profiling process,the removal threshold of the grinding wheel material under the experimental conditions was calculated to be 5.913×10⁷W/mm².The method of laser scanning path division was proposed,and the profiling trajectory of V-shaped grinding wheel was calculated and designed.The designed trajectory was tested by the profiling experiment,and the difference between the designed value and the tested value of the trajectory length was within 0.04 mm,which verifies the accuracy of the designed trajectory The V-shaped resin-bonded diamond wheel was profiled by trajectory planning method,which took 6.3h.Compared with the efficiency of traditional profiling method,it was found that the time was saved by2.3h,and efficiency was increased by 27%.2)The changes in the surface topography of abrasive grains and bond on the grinding wheel from the initial stage to the final stage during the laser profiling process were observed.It was found that when using higher laser power,with the advancement of the profiling stage,the morphology and quality of the diamond grains on the surface of the grinding wheel would become better.This was because during the profiling process,the laser irradiation power density gradually decreases,and the deterioration of abrasive grains in the early stage would be inhibited in the later stage.Adding auxiliary side blowing gas in finishing stage could effectively inhibit the deterioration of abrasive grains.By increasing the number of laser scanning tracks,the overlap rate of laser trajectory O_l was improved.With the increase of O_l from-75%to75%,the surface roughness R_a of grinding wheel decreased from 3.102μm to2.327μm,and the R_z was decreased from 17.824μm to 11.654μm;the circlular runout in the cross section of the grinding wheel decreased from 54μm to 8μm,the ontour accuracy was improved.Profiling experiment was carried out on the grinding wheel with different grain sizes of 80^#,120^#,400^#and 600^#,the diamond grain with sharp tips on the V-shaped grinding wheel were observed.The V-tip arc radius r_a of the profiling grinding wheel were measured to be 15.5μm,18.4μm,12.6μm and 13.9μm;and the angle errors e_a were 0.17°,0.07°,0.15°and 0.01°respectively.The circular runout value of the grinding wheel before profiling decreased from 23μm to within 9μm,and the surface roughness of the fine-grained grinding wheel after profiling was slightly lower than that of the coarse-grained grinding wheel.3)The variation of laser energy on the surface of V-shaped grinding wheel during dressing was theoretically analyzed.The variation law of laser energy at different coordinates of grinding wheel contour was calculated.It was found that in the process of V-shaped grinding wheel sharpening,the laser cutting depth C_d was the main influencing factor of the change of laser power density.It was found by calculation that when C_d was within 4.5mm,the bond material was removed evenly.Using the method of spectral monitoring and analysis,it was obtained that under the experimental conditions,the laser power corresponding to the damage threshold of diamond grains was 11W,and the corresponding change in irradiation power density was 11.2776×10⁷W/mm^2.The method proposed in this paper is used to dress two kinds of grinding wheels used in enterprises.The contour accuracy and microscopic topography of the grinding wheel surface after dressing meet the requirements.