Foreword makes ceaseless progress of the technology as machinery, machine tool industry product of this one replacement transfers and already also got developing quickly to numerical control machine tool from the traditional machine tool in the past. The popularity rate year after year of numerical control machine tool rises, main reason depends on the advantage of numerical control technology. Numerical control technology is applicable aviation, shipbuilding, Ning Zhoufei of the national defence industry such as production of travel, weapon produce and development rises, it is special apply to treatment precision appearance of tall, geometry complex, dimension various, remodel is frequent in the production of mechanical spare parts of small lot. Begin to consider from 40 time evening in abroad, as the development of transistor integrated circuit and computational technology, the fifties 60 time initial stage begins end use at production, and more and more ground receives promotion and application. At present with respect to our country the technical level of manufacturing industry and economy grow a condition and talk, machine tool of economy numerical control is to suit our country enterprise and relevant industry to use quite, current of this kind of machine tool have rate is higher, majority belongs to open loop or system of half closed-loop control, its machine precision the mechanical precision effect that very old rate suffers a machine tool, had solved the machining error problem that brings as a result of mechanical clearance consequently, it is the important segment that assures to machine quality. Error of clearance of machinery of machine tool of numerical control of error of clearance of analysis of error of clearance of numerical control machine tool is to show the head end from machine tool kinematic chain comes the integrated error that carries out a whole journey to be caused as a result of mechanical clearance, if pursue,1 is shown. The feed catenary of the machine tool, clearance of nut of the clearance that connection of the key in the clearance that causes by key connection between the clearance that its source of error causes as a result of key couplet at electric crankshaft and tine axis, gear deputy clearance, gear and guide screw, shaft coupling causes, guide screw. Error of machine tool backlash is to point to the existence as a result of clearance of the machinery in catenary of machine tool drive, the machine tool is carried out in athletic process, from turning into to move reversely to motion, carry out carry momentum and theoretical value (process designing is worth) existence error, reflect the processes precision error that goes up to workpiece for overlay finally. Be in when workbench of numerical control machine tool on its movement way when inverting, the existence as a result of backlash can bring about idling of servo electric machinery and workbench does not have real shift, this says move to break. If be when G01 cutting motion, retrorse deviation can affect the precision that interpolation moves, if deviation passes to be able to be caused greatly " round insufficient circle, square not quite square " case; And in motion of Goo fast fixed position, retrorse deviation affects the fixed position precision of the machine tool, make bore, bore hole the between each aperture position loss of accuracy when treatment waiting for aperture. If such backlash is numeric lesser, do not need to take any step not quite to machining precision to affect; If numerical value is greater, criterion systematic stability drops apparently, treatment precision is reduced apparently, especially curvilinear treatment, can affect the consistency of dimension public errand and curve, must undertake backlash right now determine and compensate. Use the numerical control machine tool of half closed-loop control especially, backlash can affect fixed position precision and repeat fixed position precision, this needs us to be at ordinary times when machine tool of use numerical control, the generation factor that take seriously and studies backlash, influence and compensation function, learning and the error of a few regularity in discovering backlash compensates a process automatically is summed up seriously in practice, take proper treatment step, raise the treatment precision of the spare parts. Graph the formation of 1 backlash the measurement of principle clearance error for very good research backlash error the influence to treatment, our have the aid of a diminutive is three-dimensional coordinate education and solid example platform. This platform is compositive controller of much axis motion, electric machinery reachs his drive, electronic-controlled the component such as platform of box, campaign. Machine is those who use transmission of ball guide screw is modular crossed work platform, with with implementation target contrail and movement. Executive device used a pace to enter electric machinery, control equipment by Pc machine, be based on motion of Dsp closed circuit to control the composition such as card and corresponding driver. Motion controls card to accept the position that Pc machine issues and orbit statement, undertake planning to handle, change into the statement form that servo drive can accept, send servo driver, undertake handle and magnifying by servo driver, output gives executive unit. Graph 2 backlash measure an interface to choose among them X axis, open among them the control software about measuring backlash (show 2 times like the graph) , begin to measure this axis platform the backlash error in athletic process. (1) move through the hand adjust the position that makes platform park appropriate, what approach platform commonly is deputy paragraph, install for workpiece origin. (2) the athletic distance that is apart from the input in inputting casing to need a test in motion, input in backlash input casing again 0, do not undertake clearance is compensated. (3) press using button to the dot, allow guide screw day square is apart from small paragraph one to motion (about 10mm) , nod next suspend campaign. (4) press test pushbutton, the test distance that can automatic basis inputs the system has a test, show test result finally. (5) repeat above act, measure backlash for many times. Get X axis square is worth to athletic backlash. (6) the method on in order to, press retrorse dot uses button, test X axis turns over the backlash that direction moves, if the watch is shown 1 times,measure an outcome. (7) the average of two groups of data makes cipher out be respectively: X axis square is to athletic backlash - 0.
482, the backlash that X axis turns over direction to move is 0.
480. Error of clearance of numerical control machine tool compensates the characteristic that is aimed at oneself of numerical control machine tool to reach use requirement, average numerical control system has commonly used compensation function, if nod positional deviation compensation to the knife, compensation of cutting tool radius, knife all sorts of automatic compensation functions such as compensation of radius compensation, mechanical backlash parameter. Among them compensation method of mechanical backlash parameter is one of methods with at present commonly used system of open loop, half closed circuit. This kind of method, the principle is to pass cost of error of backlash of actual measurement machine tool, the systematic parameter that in using a machine tool to control a system, sets will realize the automatic compensation of clearance error. Its process is: The clearance error of each movement rod is worth actual measurement, key in control unit through Control Panel next can, when the machine tool takes a knife after, be in above all corresponding direction (take a knife like jump or transverse take a knife) when taking a knife reversely, foregone clearance is worth, take needs numerical value again next, consequently former clearance error is able to compensate. Because this kind of method is to use programme controll of a control the retrorse feed in all programs, because this wants to input a few narrow gap only,be worth the clearance error in can compensating all treatment process, this method goes easily simply, to machine program write also do not have an influence. Particular operation: The backlash input that if the graph is shown 2 times,is in is joined in casing in front beg the backlash that go out to compensate a value, measure compensation precision again. But the clearance error value that the control basis of this method is the each motion shaft that actual measurement gets, because this suffers,measure the effect of the error. The measurement that expresses 1 backlash the place that data is not worth under its existence: Because ⑴ moves the clearance value between the guide screw in key and nut is shown endlong in guide screw nonlinear relation, because this is represented with a measured value in all integrated clearance error is unreasonable, add error of the existence when measuring clearance to be worth, accuracy of this kind of compensation method is accordingly inferior; The integrated clearance error of catenary of ⑵ general feed is measure below static condition those who go out, and the machine tool is actual work below dynamic environment, consequently static receiver error and dynamic error have bigger difference. Because of this kind of compensation method cannot real compensation is real error; ⑶ cannot compensate the error that causes because of cutting force. The place on last word put together is narrated, backlash error compensation is the important step that numerical control machine tool assures to its machine precision. Systematic parameter compensation method does not affect machine program write, yi Cao is made, simple palpability, certain effect is had inside certain limits, but limitation is bigger. Effect of machine program compensation method is better, apply to system of open loop, half closed circuit, have bigger practical effect to compensating functional system especially. But this kind of method, increased a spare parts to machine the complexity of process designing, have higher demand to using the process designing skill of personnel. After backlash value inputs numerical control system, numerical control machine tool can compensate this value automatically when treatment. But use for a long time of the machine tool as numerical control, backlash can wear away because of kinematic pair and increase gradually, because this must is opposite regularly,the backlash value of numerical control machine tool undertakes determine and be compensatinged, decrease greatly thereby or eliminate backlash to machine the undesirable effect that precision produces to machine tool precision, workpiece. CNC Milling