| With the development of automation and intelligence in manufacturing industry,customized manufacturing has become a trend,China is a big country of spectacle lens manufacturing and demand,but the customized processing technology has been monopolized by developed countries for a long time.In view of the demand of lens customization,this paper completed the algorithm research from lens surface description mehod to turn milling path planning and then to NC program implementation,which provides the basis for the development of customized turn milling lens working face specialized software.The research contents are as follows:(1)Aiming at the various expressions of the lens working surface,a unified description method for the B-spline surface of the lens working surface is given.Taking the working surface of a spherical cylindrical compound lens as an example,based on the given lens parameters and the base arc of the lens,the maximum curvature point is obtained according to the surface height vector equation of the lens working surface;for the section curve passing through this point,according to B urve theory,the inversion of the control point based on the chord length parameterization method for the type value points at different node vector increments,and the B-spline fitting curve of the cross-sectional curve at this point is obtained;and it is compared with the original curve,Then,according to the given allowable error,an appropriate increment of are length is determined and projected on the XY plane,and the projected length is used as the smallest increment of the node vector to tablish the B-spline surface of the lens working surface.(2)According to different machining paths and path generation methods in machining,the tool path planning of turning and milling machining path of spherical column composite lens working face is carried out,and the circumferential dispersion of tool contact is analyzed,According to the characteristics of equiangular discretization,the formula of equiangular discrete spiral path is given.The angle step and row spacing in the spiral path formula are calculated,and the spiral trajectory data of B-spline surface are determined.In order to make the lens working surface can be cut by the cutter,the initial tool contact point and cutter location are calculated from the lens center along the edge direction of the spiral trajectory line on the B-spline surface According to the constraints of the motion of turn milling machine tool,the initial tool contact point is modified iteratively,and the tool location of turn milling machining is given finally,thus the tool path planning method of turn milling lens working face is formed.(3)Simulate the planned path,establish a machining simulation environment for the existing machine tool through the machining simulation software,import the program derived from the turning and milling algorithm,and perform a valid machining simulation on it.Comparison of B-spline surfaces and analysis of residual and over-cutting confirmed the correctness of the turning and milling trajectory planning algorithm;for the determination of the machine tool motion parameters in the lens processing process,starting from the processing quality,for the cutting of resin CR39 At present,there is a problem of lack of reference to process parameters.The roughness is used as an index,and a three-factor five-level toroidal disk cutting orthogonal experiment is performed on the cutting speed,the amount of knife eating,and the feed per tooth,and the PCD disk knife is obtained The optimal cutting amount for resin CR39 cutting,and based on experimental data and multiple regression analysis methods,an empirical formula for surface roughness is given to reflect the influence of cutting amount on the surface roughness of resin CR39.Based on the experimental results,it is given The reasonable range of the machine tool motion parameters for processing resin CR39 was obtained,and actual cutting experiments were carried out based on this. |
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