A novel centerless grinding method based on the cup wheel for slender ceramic tubes and stability of the rounding process

Abstract

High-precision grinding of slender ceramic tubes presents an extreme challenge due to their structural features of the large length-diameter (L/D) ratio and the material property of the high hardness and brittleness. This study proposes an inclined axis centerless grinding method based on cup wheel grinding for the manufacturing of slender ceramic tubes with a large L/D ratio. The geometric characteristics of the grinding zone in the method were investigated, and the rounding process stability was analysed. The investigation reveals that the workrest angle and the work height of tubes are key process parameters for rounding process stability. Both excessively high and low work heights lead to increased roundness errors. The grinding point at the 30° workrest angle and 6.5 mm work height yielded optimal roundness. The changes in the geometric region resulting from the angle of the workrest and the working height have a significantly greater impact on the stability of circular grinding than variations in the grinding parameters. Finally, 1000 mm SiC ceramic tubes (the L/D ratio of 1:120) with excellent dimensional and shape consistency were successfully produced using this method. The tubes achieved an outer diameter dimensional error of 0.01–0.015 mm, an average roundness error of 2.168 μm, an average cylindrical error of 5.915 μm, and a surface roughness of approximately 0.3 μm. This method offers an effective solution for high-precision cylindrical machining of slender ceramic tubes.