Study on the manufacturing process controlling for aspheric surface ballonet polishing

Ballonet polishing tools, soft gasbags filled with compressed gas, have already been one of the most reliable tools in curved surface polishing due to their adaptability to change their shape to fit the worked surfaces with the same contact stress everywhere. When the internal pressure of the gasbag is adjusted on-line, the contact stress could be controlled as you want. But, because of the tensile stress of the gasbag's material, the internal pressure could not identify the real contact condition anymore. In this paper, the contact force is used to identify the real contact condition for workpieces of aspheric surfaces which is indispensable to the polishing process control. Based on the measured internal pressure of the gasbag and the on-line-controlled contact force in the normal direction, this paper studies the arithmetic of the contact area for aspheric surfaces, finds a way to eliminate the great difference of machining speed, and advances an arithmetic of the machining time for material removal controlling in the process of aspheric surface ballonet polishing. A real ballonet polishing system is developed for aspheric surfaces, and experiments show that it is a better way by controlling the contact force rather than by controlling the internal pressure in the process of aspheric surface ballonet polishing.