Study On Micro-Aspherical Surface Ultra-precision Fixed-point Turning/Grinding Technology Base On B Axis Controlling

In recent years, with the applications of high-performance aspheric optical parts in theaerospace, optics, electronics, military weapons and more fields widely, the demanding ofmachining accuracy and ultra-precision machining technologies on micro aspherical opticalparts have increased acutely, and how to obtain high performance micro optical lens hasbecome the key and difficult point for optical system design and manufacturing.With themature of aspheric plastic and glass molding technology, the mass production of asphericaloptical components has been achieved, and the main manufacturing technologyies foraspherical mold are turning and grinding technology. Therefore, the studies on turning andgrinding technologyies for ultra-precision micro aspheric parts have more importanttheoretical and practical significance.Firstly, the present aspherical ultra-precision machining technologies in domestic andinternational are introduced as well as the mainstream ultra-precision machines. The currentproblems on ultra-precision turning and grinding technology for micro aspherical optical partsare investigated in details, and corresponding solutions are put forward. Then, base on thetraditional two-axis aspheric ultra-precision turning and grinding technology, the three-axisfixed-point ultra-precision turning and grinding technologies based on controlling B axis areinvestigated, and the corresponding prediction mathmatical models of profile error wereestablished, as the influence laws of them on the form accuracy, surface quality, tool wearwere analyzed. Some common aspherical measuring technologies in ultra-precision machiningprocess are introduced, and the on machine measuring technology combining with a contactprobe and the laser interferometer measurement and the principle of probe calibration areinvestigated. The error sources in machining process and systematic errors in installation ofaspherical turning and grinding are analyzed deeply, including the tool centering error in X,Y-axis direction. The error compensation methods using in this paper are introduced, and theprinciple for machining position error and form error compensation and of compensation areemphasized to analyze, including X, Y axis centering error compensation, tool radiuscompensation, and form error compensation using polynomial fitting by leastsquare method.Focusing on different materials such as copper, aluminum, silicon and sulfur halogeninfrared glass, some comparative turning experiments using X, Z axis and X, Z, B axis for flat,concave spherical, small concave and convex aspherical surface are carried on in the samemachining conditions, and the influences of the two machining modes on the workpiece form error, surface quality, compensation technique are investigaged and anaylzed deeply in theturning process. The corresponding grinding wheel dressing technology is researched, andsetting principle and method between B-axis and wheel is introduced. Focusing on tungstencarbide and silicon materials, some comparative grinding experiments using X, Z axis and X,Z, B axis for small concave spherical, small concave and convex aspherical surface are carriedon in the same machining conditions. And influences of the two machining modes on theworkpiece form error, surface quality, compensation technique are investigaged and analyzeddeeply in the grinding process. Finally, the three axes machining mode based on B axiscontrolling may improve machining accuracy of aspherical workpiece.