AbstractHigh-quality structures featuring functional planes (e.g., machine tool guide trail with unique textures) and non-flat surfaces (e.g., aircraft engine tenon tooth with low tolerance) are essential parts of high value-added industrial equipment components. They usually need grinding as the finishing process to meet the severe requirements like high precision for assembling, high efficiency for industrial production, high profile accuracy keeping ability and lower cost for large batch orders. Typically, textured and profiled grinding wheels are expected to be the two most capable tools to be selected for these demanding structures in many cases. Therefore, the need to find appropriate methods to develop these high-performance structured grinding tools has been highly emphasised.
Among these existing machining or dressing strategies (e.g., mechanical, chemical, thermal or energy beam), laser ablation has been keeping considered the most promising way for the fabrication process of these special tools thanks to the advantages like high efficiency, no tool wear, environmentally friendly. Nevertheless, the precise fabrication of these structured (textured and profiled) grinding wheels has kept an open question as it would be pretty challenging to remove the ultra-high hardness of abrasives embedded in porous bond agents in a controllable way. Therefore, solving the widely concerned particular fabrication-induced issues has a significant sense.
To this end, a systematic research scheme including theoretical analysis, model simulation and experimental study is formulated in this research based on the previous studies. Firstly, an analytical model regarding the temperature field distribution and ablation depth involved in the ablation process is calculated, and the fundamental law is experimentally validated. Secondly, a controllable electromechanical laser ablation system with a stable CO2 laser beam generator and a precise positioning platform is established, and the functional performance is evaluated by generating irregular patterns (e.g., sine slots and variable depth zigzag groove). Then, the strategies to remove target materials on the grinding wheel in a controllable and optimum way are investigated based on the model and the laser ablation system. Afterwards, the flat grinding wheels with regular patterns (e.g., tilt slots, parallelogram, triangle, hexagon and rectangle) are generated after the experimental work regarding the ablation law of laser feed rate and laser power on ablation depth and width is carried out. Finally, the topographies of the ablated slots changing with laser power, duty cycle, feed rate and track overlap rate are studied. The possibilities to generate precise profiled grinding wheels (including stepped wheels and curved surface wheels) respectively by a single pass, multiple-pass, and a combination of feed rate, overlap rate, and focal length are addressed. The research in the thesis is anticipated to solve the urgent precise fabrication-related issues in machining high-performance abrasive tools, which has significant value in both academic research and industrial application.
|Date of Award
|Adam Rushworth (Supervisor), Hao Chen (Supervisor) & Dragos Axinte (Supervisor)