How to correctly use laser interferometer to impro

How to correctly use laser interferometer to improve the positioning accuracy of CNC machine tools

during the operation of CNC machine tools, its positioning accuracy will produce a certain degree (1). Selection of dial: before the experiment, there should be an estimation error of the maximum load, the correct use of laser interferometer and a comprehensive and scientific analysis can effectively improve the positioning accuracy of CNC machine tools

with the popularity of the application of CNC machine tools, using laser interferometer to detect the positioning accuracy of CNC machine tools has become a recognized efficient and high-precision detection method. Different machine tools use laser interferometer to detect the accuracy curve will be the same, so it is necessary to give a comprehensive and scientific analysis of different test results. The following is an analysis of the common error curves of the positioning accuracy of CNC machine tools, and selle Royal does not stop here: the protective material of the nose of the cushion is made of up to 95% biological materials, and we will discuss effective solutions together. The engine running with electromechanical control mechanical components

1, negative slope

negative slope curve, outward operation and inward operation of the two tests have a downward slope. In the whole axis length, the error increases linearly and negatively, which means that the distance measured by the laser system is shorter than the distance indicated by the machine tool position feedback system. There are two possible reasons for the negative slope: (1) the beam alignment adjustment is incorrect. If the axis is shorter than 1m, it may be that the material thermal expansion compensation coefficient is incorrect, the material temperature measurement is incorrect, or the wavelength compensation is incorrect. (2) Pitch and torsion pendulum cause Abbe offset error and machine tool linearity error

in view of the above problems, the measures that can be taken are: if the axis stroke is very short, check the alignment of the laser; Check whether EC10 and measuring head are connected and respond; Check whether the entered manual environment data is correct; Check whether the material sensor is correctly positioned and whether the input expansion coefficient is correct; Use the angle optical lens group to measure again, and check the pitching and twisting errors of the machine tool

2. Positive slope

positive slope curve refers to the linear positive increase of error on the whole axis length. This phenomenon may occur in the following ways: (1) the material thermal expansion compensation coefficient is incorrect, the material temperature measurement is incorrect, or the wavelength compensation is incorrect. (2) Pitch and torsion pendulum cause Abbe offset error and linear error of machine tool

to solve these problems, the following measures can be taken: check whether EC10 and sensor are connected and respond, or check whether the entered manual environment data is correct; Check whether the material sensor is correctly positioned and whether the input expansion coefficient is correct; Use the angle optical lens group to measure again, and check the pitching and twisting errors of the machine tool

3. Periodic curve

periodic curve is the repetition period error on the whole axis length. The pitch along the axis remains unchanged, but the amplitude may change. The possible causes of the periodic curve are mainly the problems of the machine tool, such as the failure of the lead screw or transmission system, the encoder problem or failure, and the axis straightness of the long gantry machine tool track

in view of the above problems, it is recommended to use a small sampling point interval to measure again in a pitching cycle to confirm the pitching error. As a guiding principle, if you want to check the periodic influence of a certain component of the machine tool, you can set the sampling interval to 1/8 of the expected periodic pitch, and then confirm the possible error source by comparing the pitch of the machine screw, the pitch of the rack, the encoder, the resolver or the pitch of the ball grid ruler, the distance between the support points of the long gantry track, etc. For example, if the error period is 20mm, referring to the machine tool manual, we find that the lead distance of the lead screw is also 20mm. Obviously, the error may be related to the rotation of the lead screw. The lead screw may be bent during the latest maintenance or machine tool movement, or the lead screw rotates eccentrically

4. Offset

offset refers to the constant vertical offset between the two tests of the outgoing and return journey. The possible causes of the offset curve are mainly the problems of the machine tool, such as the uncompensated or improper compensation of the reverse clearance, the gap (looseness) between the frame and the guide rail, etc

the following measures can be taken to solve the above problems: lead screw/ball screw drive; Check whether the ball nut or lead screw is worn; Check the end float of the lead screw bearing; Use the angle light wa → WB spectrum with a slope of 3dB to check the angular clearance of the frame when the axis is reversed; Check whether the reverse clearance compensation set in the controller is correct; Frame and pinion drive; Check whether the teeth engage correctly; Check the gearbox for wear and the condition of the linear encoder system

5. Dovetail

Figure 1 shows the downward slope in the off trip test. The return trip test is the mirror image of the off trip test. The deviation (or lag or reverse gap) between the off trip and return trip tests gradually increases as the axis leaves the driven end. The possible causes of dovetail shape are mainly the problems of machine tools, such as the torsion of ball screws, too tight guide rails, incorrect error compensation values, etc

Figure 1 dovetail error curve

in view of the above problems, the following suggestions are made: check the lubrication of the lead screw and guide rail; Check the balancing effect on the vertical axis; Check and adjust the guide rail clamping strip; Check whether the guide rail cover is biting and check the controller compensation

6. Positive and negative cross lines

positive and negative cross lines mean that positive (outward) operation produces a negative slope, while negative (inward) operation produces a positive slope. This is a special example of lead screw torsion, in which unidirectional linear error compensation and unidirectional value have been set in the controller

measures can be taken to solve these problems: check the lubrication of the lead screw and guide rail; Check the balancing effect on the vertical axis; Check and adjust the guide rail clamping strip; Check whether the guide rail cover is biting; Check the controller compensation

if the user plans to complete most of the work in the middle of the axis, the current compensation can be considered as the best solution, because it distributes the maximum error at the end of the axis and the minimum error at the middle position. Deleting error compensation will produce a swallow tail shape