The interpolation in CNC Machining

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The spare parts outline that summarizes treatment of numerical control machine tool is comprised by linear, circular arc commonly, also a few is not round curve outline for example tall curved surface of second curve, list curve, list, but can use linear or circular arc goes approaching, should press each to write CNC Machining program with the data of circular arc line segment point-blank, and when system of the input, numerical control that start works, numerical control system has block inputting processing, interpolation operation, output is handled, control servo orgnaization as a result by computation, thereby the servo orgnaization of machine tool of drive numerical control, make cutting tool and spare parts make the accurate opposite motion that accords with each block completely, final treatment gives the part that accords with a requirement. Interpolation computation is the basic data that basis of numerical control system inputs, be like linear terminus speed of value of start of coordinate value, circular arc, the centre of a circle, terminal coordinate, feed, pass computation, the appearance of workpiece outline the description comes out, the basis side computation calculates the edge to issue feed statement to each coordinate as a result. Interpolation is the job that according to limited message the data that finish changes closely actually, no matter be hardware numerical control or CNC numerical control, interpolation module is indispensable, the module that can fulfil interpolation function or device call interpolation implement. Interpolation method can classify so: Interpolation implement, 2 interpolation implement and tall second interpolation implement this differentiates according to mathematical model, if linear interpolation is interpolation, circle or parabola interpolation are 2 interpolation. Hardware interpolation and software interpolation are general, the interpolation module of hardware numerical control is comprised by digital circuit, rate is rapidder, but upgrade not easy, flexible poorer, call hardware interpolation. The interpolation module of CNC numerical control comes true by software, although speed is fast without hardware interpolation, but upgrade easily, cost is lower also, call software interpolation. Fiducial pulse interpolation and data sampling interpolation are fiducial pulse interpolation (: ) of interpolation of journey scalar quantity, pulse increment interpolation: The characteristic is numerical control device is in every time after interpolation ends, output fiducial pulse alignment to corresponding athletic coordinate, every pulse represented the smallest displacement, the frequency of pulse alignment represented coordinate motion rate, the amount of pulse represents athletic rate. Because this method involves addition and shift calculation only, implementation rises simpler, come true easily with hardware. More commonly used have: Digital pulse multiplier (: BinaryRateMultiplier of binary scale multiplier, pointwise of abbreviation BRM)   compares a standard (call area differentiate the law again)   number integration method (abbreviation DDA law) law of   vector differentiate compares integration method dot of target of law of the smallest error dogs law weak condition tracks a law direct function law imposes close differentiate and double differentiate standard.

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Data sampling interpolation (: Interpolation of time scalar quantity, digital increment interpolation) the characteristic is generation of numerical control device is not individual pulse however binary word, apply to closed circuit, half closed circuit to make the control system of drive of dc servo electric machinery. It can differentiate two phase: Thick interpolation: Approach with small straight line segment given outline, this small straight line segment and instruction are given speed is concerned, commonly used software comes true. Interpolation of essence of life: Undertake on afore-mentioned small straight line segment " those who count foothold is close change " , this one phase is pair of linear pulse increment interpolation actually, calculation is simple, can come true with hardware or software. Method of commonly used data sampling interpolation is below: Linear function law is patulous DDA law 2 rank angle of law of DDA of word of even numbers of law of recursive and patulous DDA approachs circular arc interpolation to improve Tusidingfa.

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CNC Milling