Linear, circular arc kind the outline of the spare parts is comprised by linear, circular arc commonly. The node between element of photograph adjacent geometry or point of tangency say for base point, be like two linear node, linear wait with the point of tangency of circular arc. Because at present system of machine tool numerical control has function of interpolation of linear, circular arc, because of the CNC Machining of spare parts of this planar to what form by linear, circular arc outline, its maths processing is simpler, coordinate of main computation base point. The computational method of base point can be to pass simultaneous equations group to seek solution, also can use the trigonometric function relation between geometrical element to seek solution. Exemple plan institute shows a part in, a, B, C, D, E is base point. The coordinate value of A, B, D, E is found out very easily from inside the graph, c drop is steep with circular arc point of tangency, want simultaneous equations to seek solution. Graph the base point computation of 1 spare parts is computational coordinate with B dot is origin, couplet establishs following equation: Linear equation: Y=tg(α + β ) equation of X circular arc: (X-80) 2 + (Y-14) 2 =30 can be gotten (64.
5507) , conversion arrives to nod the process designing coordinate that is origin with A in the department, c dot coordinate is (64.
5507) . Can see, to so simple spare parts, the computation of base point is very troublesome. To complex part, its computation workload cans be imagined, to improve process designing efficiency, applicable CAD/CAM software assists process designing. CNC Milling