The Research On Dressing Of V-Shaped Concave Bronze-Bonded Diamond Wheels With Different Pulsed Laser

As some difficult-to-machine materials,such as the engineering ceramics,optical glass and cemented carbide,have been widely used in various key equipments,more and more complex shaped parts are needed to be grinded.Although kinds of non-conventional machining methods have been brought up,grinding with super hard abrasive forming wheels is still the most practical machining method.In spite of the fact that bronze-bonded diamond grinding forming wheels behave well in machining,the difficulties in the production and dressing of concave-surface grinding wheels with conventional approaches have been extremely prominent.With the rapid development of laser technology,the picosecond laser,which can achieve "cold machining",has been popularized in industry market.Thus,a composite dressing test platform is established in this thesis,which profiling V-shaped concave bronze-diamond grinding wheel with nanosecond pulse laser and dressing with picosecond pulse laser.The primary research work and results of the thesis are listed below:(1)Based on pulse laser tangential shaping method,profiling the V-shaped concave surfaces of bronze-bonded diamond grinding wheel by nanosecond pulse laser has been carried out.The influence principles of different laser parameters on the efficiency of V-shaped concave surfaces trimming are analysed,as well as the influence of different overlap ratio rate on the geometric characteristic parameters of V-shaped concave surfaces of bronze-diamond grinding wheel.The results show that the average laser power and the laser spot overlap ratio influence the dressing efficiency significantly,approximately in proportional relationship;in addition,the appropriate overlap ratio is beneficial for the reduction of the form error PV(The minimum form error PV is 36um).Compared with laser track line overlap ratio,the laser spot overlap ratio has a greater influence on the forming angle and the radius of curvature of the V-shaped concave surfaces.The larger the laser spot overlap ratio is,the larger the forming angle and the V-shape radius will be.The grinding wheel form error can be controlled within 5%after profiling.(2)The picosecond laser pulse ablation experiment is carried out,and the ablation thresholds of bronze-bonded and diamond abrasive particle are measured respectively.The results indicate that the single-pulse ablation thresholds of bronze-bonded are 0.89J/cm,0.24J/cm~2 during strong/gentle ablation stages 1.69J/cm~2,0.49J/cm~2 during strong/gentle ablation stages respectively.Obviously,diamond grits have less thermal damage during the process of gentle ablation.(3)The influence principles of different picosecond laser parameters on the bronze-bonded and diamond abrasive of the V-shaped concave surfaces are analyzed.The results indicate that the laser beam scanning speed has a larger effect on the surface roughness of the bronze-bonded,and the faster scanning speed is helpful to create the better surface.Larger laser pulse energy,smaller laser scanning line spacing and slower scanning speed,all result in the larger thermal damage of diamond abrasive grits,which lead to bad grinding performance.The V-shaped concave grinding wheel is dressed by using the optimized laser processing parameters,and the shape of the V-shaped concave surface is still controlled well after dressing.The bronze-bonded is relatively smooth and organizational stability,and the diamond grits have suitable prominent height whose value is 13.97?m,which are beneficial to maintain the good grinding performance of dressed V-shaped concave grinding wheels.