Correct use of laser interferometer Nc machine tool positioning accuracy

Published on 2018-03-27

Nc machine tool in the process of operation, its positioning precision will produce a certain error, correct use of laser interferometer, and carry on comprehensive analysis scientifically, which can effectively improve the positioning precision of the nc machine tools.With the popularity of CNC machine tool application, positioning accuracy of CNC machine tool detection with laser interferometer has become recognized as high efficiency, high precision detection method at present.Different machine use the precision of laser interferometer test curve are the same, so you need to different test results to give a comprehensive and scientific analysis.In the face of the numerical control machine tool positioning accuracy under common error curve analysis, and explore effective solutions with everybody together.Correct use of laser interferometer Improve the nc machine tool positioning accuracy 1, negative slope negative slope curve run outward and inward run two tests are a downward slope.On the whole length of axis, a linear negative error increases, which means that the laser measuring system of distance is short in the machine tool position feedback system instructions.The possible cause of the negative slope has the following two kinds: (1) beam collimation adjustment is not correct.If the axis is shorter than 1 m could be material coefficient of thermal expansion compensation is not correct, the material temperature measurement is not correct or wavelength compensation is not correct.(2) the pitch and twist caused by abbe bias error, linear error of machine tool.Can solve these problems, the measures are: if the axis of the schedule is very short, check the laser collimation;Check whether the EC10 and measuring head is connected with reaction;Check the input manually environmental data is correct;Check whether the material sensor is the coefficient of expansion of correct positioning and input is correct;Using point of optical lens to make a measurement, check machine tool error of pitch and twist.2, positive slope gradient is curve is to point to in the entire history of the axis length, error is increasing linearly.The generation of this kind of phenomenon has the following possible: (1) the material coefficient of thermal expansion compensation is not correct, the material temperature measurement is not correct or wavelength compensation is not correct.(2) the pitch and twist caused by abbe bias error, linear error of machine tool.Aimed at these problems, can take the following measures: check whether the EC10 and sensor is connected with reaction, manual environment or check the input data is correct;Check whether the material sensor is the coefficient of expansion of correct positioning and input is correct;Using point of optical lens to make a measurement, check machine tool error of pitch and twist.3, periodic curve periodic curve is the whole axis length of repeated cycle error.Along the axis of the pitch remain unchanged, but may change.May cause of the cyclical curve is mainly machine tool problems, such as a screw or driving system fault, the encoder problem or malfunction, long gantry machine tool axis straightness of the orbit.The small sample point to solve above problems recommended interval measurement on a pitch cycle again, confirm the pitch error.As a guiding principle, if you want to check the machine tool is a component of cyclical impact, sampling interval can be set as expected cyclical 1\/8 of the pitch, and then by comparing the machine screw pitch, pitch of rack, encoder and resolver or pitch ball grid ruler, long gantry orbit of the distance between the point to confirm possible error sources.For example, if the error cycle is 20 mm, refer to the machine manual we found from the guide screw is 20 mm, it is clear that the error may be associated with screw rotation problem, screw may repair or machine tool at a recent moves by bend, or eccentric screw rotation.4, offset offset refers to go and return between two tests with constant vertical migration.Possible reasons of the offset curve is mainly machine tool problems, such as reverse without compensation or improper compensation gap, gap between frame and guide rail (loose), etc.To solve above problems can take the following measures: screw\/ball screw drive;Check whether the ball nut or screw wear;Check the end floating condition of screw bearing;When using the Angle optical axis of the lens check inversion frame Angle clearance;Check the controller Settings within the backlash compensation is correct;Frame and small gear drive device;Check the teeth mesh is correct;Check the condition of gear box for wear and linear encoder system.5, swallowtail figure 1 for a downward slope in go tests, return the mirror image of the test to go go and return deviation between test (or delay or reverse clearance) increasing with the axis leaves the drive end.Possible reasons of the swallowtail mainly machine tool problems, such as ball screw reversed, guide rail is too tight, such as using error compensation values are not correct.Figure 1 dovetail shape error curve to solve above problems, have the following Suggestions: check the lead screw and guide rail lubrication;Check on the vertical shaft balance effect;Check and adjust the guide rail clamp;Check whether the guideway cover is biting and check compensation controller.6, direction, cross line direction, cross line is correct (to) run produce negative slope, and opposite (to) run a positive slope.This is a special example of screw reversed, among them, the one-way linear error compensation and SLR to value has been set in the controller.To solve these problems can adopt: check the lead screw and guide rail lubrication;Check on the vertical shaft balance effect;Check and adjust the guide rail clamp;Check whether the guideway cover is bite a;Check the compensation controller.If the user complete most of the work plan in the middle of the axis position, the current compensation can be considered to be the best solution, because it will be the biggest error distribution at the end of the axis, and the smallest error is in the middle position.Delete the error compensation will generate swallowtail graphics.(the original title: correct use the laser interferometer Nc machine tool positioning accuracy) (source: OFweek laser network)