Error of geometry of numerical control machine tool reachs his to compensate methodological research

Summary: The account that produces to error of geometry of numerical control machine tool made more detailed analysis, the compensation of systematic error the method had inducing, elaborated of all kinds error to compensate applied circumstance of the method on this foundation, those who be precision of farther implementation machine tool is soft upgrade next dozen of foundations. Keyword: Error of error of geometry of numerical control machine tool compensates preface to raise machine tool precision to have two kinds of methods. One kind is the error source that through raising a part the design, level that make and assembles eliminates a possibility, call an error to avoid a law (Errorprevention) . This method basically is machined master precision on one hand restrict, on the other hand of spare parts quality rise bring about finished cost to expand, the use that renders this method is restricted certainly. Another kind calls an error compensation method (Errorcompensation) , adopt the treatment statement of modification machine tool normally, undertake to the machine tool the error is compensated, achieve ideal athletic orbit, those who realize machine tool precision is soft upgrade. Consider to make clear, the error that geometrical sum of errors causes by temperature takes a machine tool about 70% of overall error, among them geometrical error is relatively stable, undertake the error is compensated easily. Logarithm accuses the compensation of error of machine tool geometry, can raise the treatment level of whole and mechanical industry, progress to promoting science and technology, increase capacity of our country national defence, then pole enhances the comprehensive national power of our country to have great sense greatly. The account that 1 geometry error produces thinks generally to count the geometrical error that charges a machine tool to cause by reason of the following respects: 1.

The primitive production error of 1 machine tool is to show by compositive machine tool each component works quality of geometrical appearance of the surface, surface, mutual the error of machine tool motion that the position error place between causes, it is the main reason that error of geometry of numerical control machine tool produces. 1.

The controls systematic error to include machine tool shafting servo error of 2 machine tools (outline follows error) , error of algorithm of numerical control interpolation. 1.

3 heat are out of shape the error heats up the error that disturbs to the structural heat that brings about a machine tool is out of shape and arise as a result of the inner heat source of the machine tool and environment. 1.

4 cutting bear causes machining complex to be out of shape the error that causes includes the error that machine tool, cutting tool, workpiece and clamping apparatus are out of shape place is brought about. This kind of error is called again " let a knife " , it creates the appearance distortion that machines a spare parts, when should process thin wall work especially or using long and thin cutting tool, this one error is more serious. 1.

The oscillatory error of 5 machine tools adds man-hour in cutting, numerical control machine tool because of craft flexible with working procedure changeful, its run condition to larger possibility falls into not stable area, arouse intense flutter thereby. Cause error of the exterior quality aggravation that processes work and geometrical appearance. 1.

The test error of 6 testing system includes the following fields: (1) the measurement that because measure the production error of sensor and the mounting error that its get on in the machine tool,causes the error; of itself of sensor feedback system (2) as a result of machine tool spare parts and orgnaization error and in use be out of shape cause the error that measures sensor to appear. 1.

The random error that because the metabolic place of environment and operating conditions is caused,7 outsides disturb an error. 1.

8 other error is like the error that process designing and operation mistake bring. The error above can be mixed according to the characteristic of the error property, return it is two kinds big: Namely systematic sum of errors random error. The systematic error of numerical control machine tool is the error with machine tool inherent itself, have but repeatability. The geometrical error of numerical control machine tool is his main component, also have but repeatability. Use this character, can undertake to its " measure from the line " , can use " detect from the line -- open loop is compensated " the technology will try to amend and be compensated, make its are reduced, achieve the goal of aggrandizement of machine tool precision. Random error has random sex, must use " online detect -- closed circuit is compensated " the influence that the method will come to eliminate random error to machine precision to the machine tool, this method is right measure an instrument, measure an environment the requirement is strict, be hard to popularize. 2 geometry error compensates a technology to be aimed at the different type of the error, executive error compensation can be divided it is two kinds big. Random error amends a requirement " online measure " , detect the error device is installed directly go up in the machine tool, while the machine tool works, real time ground measures the error value that gives corresponding seat, be worth with this error real time undertake correction to processing an instruction. Random error compensation does not have a requirement to the error property of the machine tool, can undertake compensating to the error of system of random sum of errors of the machine tool at the same time. But need the facility related the high accuracy measurement unit with one complete a complete set of and other, cost is too high, economic benefits is bad. Document [what 4] had temperature is online measure and compensate, fail to achieve actual application. Systematic error compensation is to use corresponding instrument to undertake detecting to the machine tool beforehand, pass namely " measure from the line " the error value that gets seat of instruction of space of machine tool work, regard the function of machine tool coordinate as them. When the machine tool works, the basis machines the coordinate of the dot, corresponding error is worth v to be amended in order to undertake. Ask the stability of the machine tool is close friends, assure the determinism of machine tool error, amend in order to facilitate, via compensating the machine tool precision after to depend on the repeatability of the machine tool and ambient conditions change. Numerical control machine tool falls in normal circumstance, repeat precision outclass its space is integrated error, the compensation of reason system error can rise the precision of the machine tool effectively, can increase the accuracy class of the machine tool even. Up to now, have a lot of domestic and internationally to the compensation method of systematic error, can divide for the following kinds of methods: 2.

Compensation method of synthesis of 1 individual error compensates a method this kind is with the error synthetic formula is academic basis, measure so that each individual and primitive error of the machine tool is worth through measuring a way directly above all, synthesize the error heft of formulary computation compensation point by the error, realize the error compensation to the machine tool thereby. Measure to 3 coordinate machine those who undertake position error is measured should belong to Leete, handle trigonometry geometry relation, derivation gave a machine tool of error of each reference axis represent a means, did not consider the impact of corner. Undertake error compensatory should be Professor Hocken earlier, in the light of model Moore5-Z (1) 3 coordinate are measured machine, inside 16 hours, measured the error of the many dot inside working space, the impact of temperature considered in this process, undertook differentiating to error pattern parameter with the least square method. The positional signal that moves as a result of the machine tool is obtained from laser interferometer directly, considered the impact of angle and linearity error, achieve more satisfactory result. 1985 G.

Zhang is measured successfully to 3 coordinate machine undertook the error is compensated. Measured workbench flatness error, divide in workbench brim numerical value largish, other does not exceed 1 μ M, test and verify the dependability that rigid body assumes. Use laser interferometer and gradienter measure 21 gotten errors, through linear coordinate commutation undertakes the error is synthesized, carried out error compensation. The experiment is measured to make clear on X-Y plane, before compensation, the dot that is more than 20 μ M in value of the error in all measurement point is occupied 20% , after compensation, the error of the drop that does not exceed 20% is more than 2 μ M, prove precision raised nearly 10 times. Measure the error of machine besides coordinate beyond compensation, compensatory of error of numerical control machine tool considered to also obtain certain positive result. 1977 Schultschik teachs the method that uses vectorgraph, analysed a machine tool each component error reachs his to be opposite the influence of geometrical precision, laid the foundation that error of machine tool geometry studies further. Ferreira and its co-worker also undertook study to this method, reached the current model of error of machine tool geometry, to individual error synthetic compensation method made contribution. J.

Nietal uses this method further compensate at on-line error, achieved idealer result. Chenetal established 32 error pattern, among them 11 redundant are concerned temperature and parameter of error of machine tool origin, to the compensation of horizontal machining center the experiment makes clear, precision raises 10 times. Eung-SukLeaetal was used almost with G.

The measurement technique like Zhang, to milling machine of 3 coordinate Bridgeport 21 errors undertook metrical, apply an error to synthesized a law to reach error pattern, the uses laser interferometer and Renishaw respectively as a result DBB system after compensation undertook examining, prove machine tool precision is able to promote. 2.

2 errors are direct requirement of this kind of method measures compensation method accurately an error of vector of machine tool space, compensation precision demand is higher, measure precision and metrical check the number to ask to jump over much, but the error that should know in detail to measure dimensional random to nod is impossible, the method that uses interpolation gets the error weight of compensation point, undertake the error is amended, requirement of this kinds of method is built and coordinate is being measured consistently absolutely when compensation is. 1981, dufour and Groppetti fall in different load and temperature condition, the error that to the machine tool working space nods undertook metrical, form error vector matrix, obtain information of machine tool error. Stock this error matrix the computer to undertake the error is compensated. Similar research basically has A.

C.

Okaforetal, work through measuring a machine tool inside the space, the standard consults an opposite error of on many bits, it is datum mark with the first, next conversion becomes absolutely coordinate error, the method that adopts interpolation undertakes the error is compensated, the result shows precision raised 2 ～ 4 times. Hooman applies three-dimensional linear (LVTDS) measurement unit, the error that gets machine tool space is nodded 27 times (resolution 0.

25 μ M, repeat precision 1 μ M) , had similar job. Consider the impact of temperature further, every are removed 1.

2 hours are measured, measure 8 times in all, compensate what undertook concerned temperature coefficient as a result to repair to the error. The insufficient place of this kind of method is to measure workload big, memory data is much. Current, still do not have completely appropriate instrument, what also restricted this method is farther apply and develop. 2.

3 opposite errors are decomposed, measurement technique of error of great majority of synthetic compensation method just got opposite integrated error, can decompose the individual error that gets a machine tool from which accordingly. Use error complex method further, to machine tool error compensation is feasible. Current, also gain certain headway domestic and internationally to the research of this respect. JunNi of American Michigan university taught directive doctoral student ChenGuiquan to make such attempt 2000, use ball lever instrument (TBB) the geometrical error below different to machine tool of 3 axes numerical control temperature undertook metrical, built fast temperature forecast and error compensation model, undertook the error is compensated. Christopher uses instrument of laser ball lever (LBB) , the error information of the machine tool was obtained inside 30 minutes, established error pattern, inside the time-interval of 9 months, to the error compensation undertook 5 times evaluating as a result, the result makes clear, through software error compensatory the method can raise the precision of the machine tool, can maintain precision to be in longer inside changeless. The error synthesizes a law, the requirement measures a machine tool each primitive error of each axis, more mature measurement technique is laser interferometer, measure precision tall. With Shuang Pin laser interferometer undertakes an error measure, need time to grow, tall to operating personnel to debug a level to ask. Mainer is right the error measures an environment the demand is high, commonly used measure at 3 coordinate of machine detect, unsuited production field work. Opposite error is decomposed, synthetic compensation method, measurement technique is relatively simple, measure can obtain whole and circumferential data information, can satisfy machine tool precision at the same time detect and machine tool evaluation. Also have the method that not little error decomposes at present, as a result of machine tool circumstance each different, find appropriate general maths model to undertake the error is decomposed hard, and affect identical primitive error to measuring an outcome cannot undertake decomposing, also popularize application hard. The direct compensation method of the error, obtain dimensional vector error to contrast with standard component commonly, have direct compensation, little intermediate link, be close to the economic condition of the machine tool more. But the standard component that obtains many information content to need to differ, come true hard, such compensation precision are restricted. In home, a lot of research organizations and college also undertook machine tool error compensates the research of the respect in last few years. The compensation research that institute of 1986 Beijing machine tool began a machine tool to heat up an error and coordinate measure the compensation research of machine. The Lishu of Tianjin university was mixed 1997 etc undertook compensatory of machine tool error builds model and research of hot error compensatory. 1998 the Liu Youwu of Tianjin university error pattern that used much system interconnected system to build a machine tool, gave out measurement technique of interferometer of laser of the 22 lines of geometrical error, 14 lines, 9 lines, they returned logarithm to accused the error compensation of the machine tool to have comprehensive research 1999, obtained delectable positive result. The Yang Jianguo of Shanghai traffic university undertook lathe heats up error compensatory to consider 1998. 1996 mix in national science foundation to 2000 the support of 863 plans project leaves the country, university of Hua Zhongke ability began logarithm to accuse error of machine tool geometry compensation and be based on the intelligence that online argue knows cutting power the research from adaptive control, obtained a few positive result. The place on put together narrates: Undertake the error of numerical control machine tool is compensated, it is crucial that the error is measured, error pattern is a foundation. Pass the compensation of the error, the OK and effective precision that raises a machine tool, make contribution to promote our country manufacturing industry the standard. CNC Milling