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In order to meet the growing demand for high-quality images, optical elements of freeform surface are more and
more applied to imaging system. However the fabrication of freeform surface optical elements is much more difficult
than that of traditional spherical ones. Recent research on freeform surface manufacture often deals with precision
machine tools which have limitations on dimensions and are always expensive. Little has been researched on industrial
robots. In this paper, a new method of freeform surface grinding based on industrial robots was found. This method
could be applied to both whole surface grinding as well as partial surface grinding. The diameter of lenses to be ground
would not be restricted to the machine tool's size. In this method a high-speed-rotating soft wheel was used. The relation
between removing amount and grinding time which could be called removing function was established and measured.
The machining precision was achieved by means of controlling the grinding time instead of the machine tool or
industrial robot itself. There are two main factors affecting the removing function: i).rotating speed of the soft wheel;
ii).pressure between the wheel and the work piece. In this paper, two groups of experiments have been conducted. One is
the removing function tested at constant rotating speed while under different pressure. The other is that tested under a
certain pressure with variable speed. Tables and curves which can show the effect of speed and pressure on the removing
efficiency have been obtained. Cause for inaccuracy between experiment data and calculated result according to the
theory and the non-linearity in the curves was analyzed. Through these analyses the removing function could be
concluded under certain condition including rotating speed and pressure. Finally several experiments were performed to
verify the appropriateness of the removing function. It could also be concluded that this method was more efficient in
comparison with traditional grinding technology particularly in the aspect of partial surface grinding. This paper also
brought up a new idea that this method could be combined with other freeform surface grinding technics to realize a
more flexible, efficient, reliable and economical type of optical fabrication. It would become a potential technic
especially for partial optical surface grinding and repair.
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