The laser interference law of error of fixed position of numerical control machine tool detects with compensation
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source:DALLMAN CNC Machining
Summary: With laser interference law measures the principle of the error, the fixed position error that compensates systematic logarithm to charge a machine tool through computer pilot error undertakes compensating, experimental result shows this kind of method can raise the fixed position precision of numerical control machine tool substantially. Keyword: Laser interference; Numerical control machine tool; Fixed position error; The error compensates the 1 preface flying development as economy of our country countryman, numerical control machine tool and machining center serve as the machine tools of new generation, in machinery wide application already received in making, of the rapid development of accurate processing technique and precision of spare parts treatment rise ceaselessly, raised taller requirement to the precision of numerical control machine tool, fixed position error is the main factor of machining error of precision of treatment of machine tool of influence numerical control, generation. Accordingly, undertake to the fixed position precision of numerical control machine tool compensation is the efficient way that assures to machine quality detecting mixing. The article is based on afore-mentioned thoughts namely, use laser interference to measure a principle, compensate a system to undertake detect and be compensatinged to numerical control machine tool through the error, make its locate precision gets rising significantly. 2 laser interference measures principle laser interference to if the graph is shown 1 times,measure a principle. 1 laser; 2 λ / 4; 3 prismatic implement; 4 check slant implement; 5 receiver; 6 polarizations are prismatic implement; 7, 8 illuminator; 9 prism pursue 1 laser interference measures a principle ｅ of graph general H - N ｅ laser 1 park is permanent in magnetic field, because Zeeman effect makes laser atomic,spectral line dissension is the or so round polarized light with contrary direction of rotation. Set two bundles of smooth amplitude identical, frequency is ｆ respectively 1 with ｆ 2(ｆ 1 with ｆ 2 differ very small) . Or so round polarized light classics λ / 4 2 hind turn oscillatory direction into mutual and perpendicular linear polarized light. Prismatic implement 3 reflex one part beam of light, classics check slants implement 4 form ｆ 1, ｆ the 2 signal that pat frequency, by receiver 5 receive for referenced signal; Another part beam of light connects beyond the mark light implement 3 enter a polarization prismatic implement 6, among them parallel is ｆ at the frequency of prismatic face the linear polarized light of 2 is passed completely prismatic implement 6 arrive at movable illuminator 8, movable illuminator 8 when moving with speed ｖ , because the Doppler effect produces ｆ of poor frequency Δ , at this moment ｆ 2 become (2+ Δ of ｆ of ｆ ′ = ｆ ) ; And perpendicular it is ｆ at the frequency of prismatic face the linear polarized light of 1 launchs fixed illuminator completely 7. From illuminator 7 and 8 launch two bundles of light that come back to arrive the polarization is prismatic implement the prismatic face assemble of 6, again via turning to prism 9, polarization implement 10, by receiver 11 receive to measure signal, the poor value that measures signal and referenced signal is much general to strap ｆ of Δ of difference on the frequency namely. Tally is inside time ｔ plan the pulse number N that takes frequency to be Δ ｆ is equivalent to be opposite inside ｔ interval ｆ is integral, namely: Reason measures distance ｌ to be λ of Nextpage ｌ =(/ the N in 2) N type- - accumulative total pulse counts λ- - laser wavelengh ｃ- - velocity of light accordingly, when mobile and movable illuminator 8 when, can get metrical is apart from through number of accumulative total pulse. When decreasing the grating feet reading that measures distance and numerical control machine tool to go up, the fixed position error that can get numerical control machine tool [1] . Machine tool of numerical control of system of compensation of error of fixed position of machine tool of 3 numerical control locates if the graph is shown 2 times,the error compensates a system. This system divides composition by the six ministries in feudal China: Interferometer of laser of numerical control machine tool, double frequency, error measures interface, error to compensate interface, computer and printer to wait. Graph 2 in, numerical control machine tool is error compensation object, interferometer of double frequency laser is used at measuring an error, the computer is systematic core, below the management that compensates software, through measuring interface to be able to use Shuang Pin laser interferometer measures the fixed position error of numerical control machine tool automatically, the fixed position error that charges a machine tool by logarithm of error compensation interface undertakes compensating, error data can pass printer to output. Graph when machine tool of 2 numerical control locates the error compensates a system to move when machine tool low speed, the computer measures interface to press certain displacement span to measure the error data sampling that go out to handle to interferometer of double frequency laser through the error, issue corresponding compensation signal; Through the error compensation interface passes the error the CNC system of numerical control machine tool, finish corresponding compensation by numerical control machine tool. Such every arrive a compensation point, the computer issues compensation signal, undertake compensating by numerical control machine tool, till journey terminus. But, afore-mentioned pointwise errors compensate the circumstance that applies to low speed motion only commonly, when the machine tool is in high speed to move, because the system answers speed not to follow to go up the motion of the machine tool, make the error compensates a system not to stabilize as a result at cannot working normally. When machine tool high speed moves, the basis does not undertake machining this one characteristic commonly, can design high speed to compensate software by following methods. Turn into from low speed when the machine tool when high speed moves, through software compensation system breaks away from compensation condition, do not undertake during high speed moves the error is compensated namely; When the machine tool returns low speed to move, the displacement that during high speed of computer cipher out moves, the machine tool has moved and do not undertake data sampling, pointwise of travel of the reentry when waiting for a system to restore low speed to move is compensated [2] . Compensate precision to rise further, fractionize can undertake to compensation point span when establish compensation point, fractionize can come true by hardware circuit. Graph correction curve of error of fixed position of machine tool of 3 numerical control 4 example are YCM to a model - VMC - of the machining center of 65 A error of X axis fixed position undertakes detecting, if the graph is shown 3 times,compensate around error curve. Its X axis locates error curve is A before compensation, the biggest error is ｍ of 57 6 μ , after the course is compensated, its X axis locates error curve is B, the biggest error is ｍ of 6 6 μ only. The fixed position error that detect and 5 last words compensate numerical control machine tool with laser interference principle is a kind of relatively practical method, can raise the fixed position precision of numerical control machine tool significantly, make its work at optimal precision condition, ensure thereby the treatment quality of numerical control machine tool. CNC MillingCNC Machining