1. Appearance and surface damage inspection
Shaft body surface inspection: Clean the output shaft mating surface (coupling mounting position, shaft shoulder, keyway), visually observe whether there are scratches, rust pits, cracks, focus on keyway edges, step transition fillets and other stress concentration areas. Small defects in these locations will directly become the source of cracks for subsequent fatigue fractures.
Verification of mating surface accuracy: After lightly tapping the shaft surface with fine sandpaper, use a micrometer to measure the roundness and cylindricity of the journal. If the value exceeds 0.02mm, it means that the shaft has been worn or plastically deformed, which will directly lead to excessive coaxiality after subsequent installation.
Keyway status confirmation: Use a feeler gauge to check the matching gap between the key and the keyway. If the gap on one side exceeds 0.1mm, it means that the keyway has been rolled and deformed, and transmission impact will occur during operation, which will accelerate shaft damage.
2. Accurate measurement of form and position tolerances
Radial runout detection: Fix the reducer horizontally, use the top to hold the center holes at both ends of the output shaft, attach the magnetic seat of the dial indicator to the rigid surface of the box, and point the needle vertically to the journal surface; manually slowly rotate the output shaft for one circle, and the difference between the maximum and minimum readings of the dial indicator is the radial runout. The qualified value of the radial runout of the DCY series reducer output shaft must be ≤0.03mm. If it exceeds the standard, it means that the shaft has been bent and deformed.
Axis movement detection: Push the shaft body along the axial direction of the output shaft, and use a dial indicator to read the axial movement amount. The normal allowable range is ≤0.1mm; if the movement exceeds the standard, it means that the output shaft bearing has been worn, and the shaft body will bear additional axial impact force during operation.
Coaxiality pre-check: Using the input shaft of the reducer as the benchmark, use the double-meter method to measure the coaxiality of the output shaft and the input shaft. The radial deviation must be controlled at ≤0.05mm to avoid the machining eccentricity of the shaft itself from being amplified into additional loads after installation.
3. No-load and hand feeling verification
Manual rotation test: Disengage the external load and manually rotate the output shaft. The entire rotation should be smooth and without jamming, and the resistance should be uniform and not tight or loose. If there is an obvious stuck point at a fixed angle, it means that there is collision damage to the gear on the shaft or the shaft itself.
Backlash and rocking inspection: Twist the output shaft at a small angle in the forward and reverse directions. The amount of circumferential rocking should not exceed 1.5 times the standard backlash of the model. If the amount of rocking is abnormally large, it means that the mating splines of the shaft and gear have become loose and damaged.
Short-term jogging test: The motor jogs to drive the reducer to run without load for 3 to 5 seconds. The output shaft should run smoothly without periodic jitter, and there should be no metal friction or impact noise at the output end. If there is regular vibration that is synchronized with the shaft speed, it means that the dynamic balance of the shaft has failed or there are hidden cracks.
