The outline appearance of object of treatment of numerical control equipment often is various, these outline are the line that waits for a model with linear, circular arc, corkscrewed yarn, parabola and free curve commonly model will describe. Afore-mentioned lines are had more or less commonly in numerical control device model control method, namely interpolation controls algorithm. Among them the basiccest is linear with circular arc interpolation. In the numerical control unit that has algorithm of some line interpolation, the work out of spare parts machine program can simplify greatly. Provide a description only commonly place of this line form must relevant parameter, if be opposite linear, offer its start and terminus; To circular arc, offer starting point terminal, suitable circle or go against circle and the centre of a circle relative to the position at start. Accordingly, to realize orbit control, a certain number of contented line intermediate points that ask with feed speed must give in computation of the real time in athletic process (between start and terminus) , this is the interpolation in numerical control technology (the concept of Interpolation) . Accordingly, can define as follows to interpolation: Alleged interpolation is according to giving feed speed is mixed give contour line model requirement, between the known drop of outline, determine a few methods of intermediate dot, this kind of method calls interpolation method or interpolation principle. And to every kinds of method (principle) may use different computational method to come true again, this kind of specific computation means says for interpolation algorithm. To outline control system, the mainest function is interpolation function, because interpolation operation has in real time in process of machine tool campaign,this is, it is namely inside limited time, must allocate corresponding position in real time to dominate information and speed control news to each reference axis. Because had interpolation function,outline control system is, ability treatment gives the part with all sorts of complex form. Can say interpolation function is the essential feature of outline control system. Accordingly, the actor bad of interpolation algorithm, the function index that affects CNC system directly. In numerical control device its realize measure to basically have 3, the interpolation process that machines with circular arc below is exemple undertake demonstrative. Next graphs are the L of circular arc contrail that is about to machine, start is P0, terminus is Pe. CNC device will use below 3 measure undertake interpolation to this circular arc: Interpolation algorithm principle pursues 1. The feed speed F of the T of interpolation time △ that approachs processing CNC device to press a system and treatment place requirement, break up L by Ll of a certain number of short linear △ , △ L2, ... , △ Li... , here: △ Li, =F △ T(i=1, 2, ... ) . Become when △ T =0, fold line segment the sum to be close to circular arc L namely: Of course, approach circular arc to existing to approach error δ with linear △ Ll, but want δ only (△ Li is enough short) enough small, always can satisfy a spare parts to machine a requirement. When F is constant, because give to system of certain numerical control Yan Heng to be constant, the length of reason △ Li also is invariable △ L, just its slope and the position on L are concerned. 2.
After inserting complementary operation to give △ Li in computation, must decompose its for X axis and Y axis shift heft is mixed (in the) inside time, they will go up in ￡ as △ grave of the position change ceaselessly and change, but they are contented: And have: Ti of △ of Yi/ of △ of Ti Fy= of △ of Xi/ of Fx= △ because the slope of △ Li is constant change, because this feed speed is in,the ratio Fx/Fy between the heft Fx of X direction and Y direction and Fy and them is changing ceaselessly. 3.
Instruction output gives consideration △ Ti inside time and as the instruction output gives X axis and Y axis, in order to dominate their linkage. From this knowable, as long as can continuously two feed axis is in automata X and Y the quantity moves inside time. With respect to the treatment that can implement curvilinear outline part. CNC Milling