INTERPOLATING SYSTEM FOR NUMERICAL CONTROLLER

PURPOSE:To provide an interpolating system for a numerical controller which can reproduce exactly the curve and the straight line of a free curved surface from the data of a given minute straight line block. CONSTITUTION:This system derives the maximum clearance TRa between circular arcs (a), (b) and (c) for connecting points (b), (c) of both ends of a minute straight line block (b)-(c) which becomes a deciding object and the starting point (a) of a front block and the minute straight line block (b)-(c) and the maximum clearance TRb between the points (b), (c) of both ends of the minute straight line block (b)-(c) and an end point (d) of a rear block. In accordance with whether the maximum clearance of a larger value is within a set value or not, whether the maximum clearance between a smooth curve for interpolating the minute straight line block (b)-(c) and the minute straight line block (b)-(c) is held in a range of the set value or not is decided and when it is held in the range, the minute straight line block (b)-(c) is subjected to curve interpolation and on the other hand, unless it is held in, the curve and the straight line of a desired free curved surface are reproduced exactly by interpolating linearly the minute straight link block (b)-(c).