Detecting the mounting coaxiality (i.e., the parallelism and alignment accuracy of the two in the direction of linear motion) of the slider and guideway is a key step in ensuring the accuracy of the linear motion system. The following are several commonly used detection methods and operation points, applicable to different precision needs of the scene:
I. Basic tool detection method (applicable to general precision scenarios)
1. Laser interferometer detection (preferred for high precision)
Tools: laser interferometer, reflector, magnetic table base.
Operation steps:
Fix the laser interferometer host on the equipment base, reflector installed on the slider (need to ensure that the reflector and the direction of movement of the slider perpendicular).
Start the laser interferometer, let the slider move along the whole guide rail, record the offset data after the laser beam reflection.
Judgment criteria: If the data fluctuations exceed the equipment design tolerance (such as ± 0.01mm / m), you need to adjust the guide rail mounting position or the slider fixing screws until the data is stabilized in the allowable range.
2. Percentage table (micrometer) detection method (general-purpose)
Tools: Percentage table (or micrometer), table stand, standard flat ruler (optional).
Operation steps:
Fix the table frame on the slider, the percentage meter probe vertically against the guide rail side (or top surface) of the reference plane.
Manually push the slider to move slowly, and observe the fluctuation of the pointer of the percentage table:
Side coaxiality: Detect the parallelism between the side of the guide rail and the direction of movement of the slider, the range of fluctuation of the pointer is the deviation value.
Height difference of the top surface: If you need to detect the height consistency of the top surface of the guide rail and the slider, you can repeat the operation with the probe against the top surface.
Adjustment points: If the deviation exceeds the deviation, loosen the guide rail mounting screws, use a copper hammer to tap the guide rail to adjust the position until the percentage meter fluctuations in the tolerance (such as ± 0.02mm), and then fix the screws.
Second, auxiliary tooling inspection method (for batch installation or complex structures)
1. Standard inspection rod / inspection tool testing
Tools: standard inspection rods (or customized inspection tools), plug ruler matched with the specifications of the rail.
Operation steps:
Place the inspection rod on the guide rail so that its axis is parallel to the direction of movement of the guide rail, and the two ends are fixed with brackets.
Set the slider on the check rod, push the slider to move the whole process, and use the plug ruler to measure the gap between the slider and the check rod:
If the gap is uniform and within tolerance (such as ≤ 0.03mm), coaxiality qualified;
If the gap is too large, need to adjust the installation height or level of the corresponding position of the guide rail (can be realized by increasing or decreasing the shims).
2. Light gap method (applicable to small guide rail or preliminary screening)
Tools: cutter ruler, light source (such as flashlight).
Operation steps:
Put the knife edge ruler close to the guide rail working surface (side or top surface), from one end to move to the other end, while observing the knife edge ruler and the guide rail surface of the light gap.
If the gap is uniform and no significant change, the guide rail straightness is good; if the gap is big or small, need to be combined with the slider to move the sense of jamming to determine the coaxial deviation, targeted adjustment of the guide rail mounting screws.
Third, the dynamic operation observation method (applicable to the scene of rapid judgment)
Operation steps:
Apply the rated load to the slider, manually or electrically to make it along the guide rail throughout the round-trip movement for many times.
Observation points:
Smoothness of movement: If the slider moves with obvious jamming, uneven resistance or abnormal noise, may be caused by coaxial deviation.
Traces of wear: After stopping the machine to check the contact surface of the slider guide, if the local abnormal wear (such as serious wear on one side), usually indicates that the installation of coaxiality is poor.
Adjustment suggestions: according to the jamming or wear location, fine-tune the guide rail corresponding to the region of the fixed screws (such as loosening with wedges or shims to adjust the gap), until the movement is smooth and no abnormality.
Fourth, precautions
Environmental requirements: testing to ensure that the equipment is stationary, no vibration, stable ambient temperature (high-precision testing needs to be carried out in a constant temperature workshop to avoid thermal expansion and contraction affect the accuracy).
Benchmark selection: Priority to the equipment base or factory labeled datum as a reference, to avoid multiple benchmarks lead to error accumulation.
Multiple measurements: Important equipments should be tested 2-3 times repeatedly, and the average value should be taken in order to exclude accidental errors.
Precision of tools: tools such as percentile tables and laser interferometers need to be calibrated regularly to ensure that the inspection data is reliable.
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