An environmentally friendly, non-contact dressing technology
Laser dressing technology has shown extremely outstanding advantages and broad application prospects in dressing of superabrasive grinding wheels. The arc-shaped resin-bonded diamond grinding wheel has been a common tool for grinding spherical, aspherical and free-form surfaces of hard and brittle materials such as optical glass and engineering ceramics. A workman must first sharpen his tools if he is to do his work well. Dressing is an important part of improving the surface contour accuracy and micro-topography of the grinding wheel, thereby improving the grinding accuracy, quality and efficiency. Unfortunately, due to the complicated axial sectional contour, the extremely high hardness of the grains, and the high holding strength of the bond, it is very difficult to precisely dress the arc-shaped resin-bonded diamond grinding wheel. A review of published literature reveals that both mechanical method or the electrical discharge methods can achieve precision dressing of fine-grained superabrasive forming grinding wheels, although they still have many drawbacks and limitations. Fortunately, as the cost-effective advantages of high-power, short-pulse lasers have become increasingly prominent, laser dressing technology is increasingly recognized and valued in recent years. This technology is expected to solve the dressing problem of superabrasive forming grinding wheels; nonetheless, there are still many pitfalls that need to be addressed.
In general, the laser dressing technology is still in its infantry stage in both research and application. As such, it is plagued with numerous bottlenecks such as poor profiling accuracy due to the difficulty of tool setting of laser beam, uncontrolled sharpening topography due to laser focus characteristics, and reduced grain performance due to ablation thermal damage. Overall, there is need for more research prior to full operationalization. To address these shortfalls, Hunan University of Science and Technology researchers: Professor Hui Deng and Dr. Zhou Xu, proposed to systematically investigate laser dressing of arc-shaped resin- bonded diamond grinding wheel with a grain size of about 180 μm. Their work is currently published in the research journal, Journal of Materials Processing Technology.
In their approach, acoustic emission monitoring technology was first introduced into laser dressing, which solved the problem of low accuracy of tool setting of laser beam. The laser tangential profiling method based on deep cutting and intermittent feeding was improved to achieve efficient and precise profiling of arc shaped grinding wheels. It took about 4.5 h to profile a parallel grinding wheel into an arc-shaped grinding wheel.
Limited by the accuracy of the experimental device, the surface contour accuracy of the arc-shaped grinding wheel after profiling was currently only about 20 μm.
The authors reported that the grains in the middle area of the surface of the grinding wheel were only slightly graphitized, and the damage degree of the grains in the edge area was more serious. Subsequently, a new method of laser sharpening based on layered scanning was proposed, which effectively reduced the difficulty of controlling the laser scanning trajectory, and achieved the uniform removal of the bond and the precise control of the grain protrusion height everywhere on the surface of the grinding wheel. In addition, it was found that the laser beam did not damage the diamond grains during the sharpening process.
In summary, the study investigated the laser dressing of the coarse-grained arc-shaped resin-bonded diamond grinding wheels for the first time. Remarkably, the authors proposed a new laser dressing process, which is the first to realize the precise profiling of the arc-shaped grinding wheel and the precise control of the surface micro-topography of the grinding wheel after sharpening. In a statement to Advances in Engineering, Professor Hui Deng mentioned that they also used this new process to achieve precise dressing of V-shaped, trapezoid- shaped, involute-shaped and other superabrasive forming grinding wheels. So far, there is no report that other scholars have successfully realized the precision dressing of involute-shaped superabrasive grinding wheels.
Hui Deng, Zhou Xu. Laser dressing of arc-shaped resin-bonded diamond grinding wheels. Journal of Materials Processing Technology. 288 (2021) 116884.