The machining methods and precautions for the UAV motor shaft core are as follows:
Machining Methods:
1. Blanking: Select a suitable blank, typically 700mm long and 65mm in diameter, made of 40Cr steel.
2. Quenching and Tempering: Perform quenching and tempering on the auxiliary and main shafts to achieve a hardness of 26-30 HRC. Quenching and tempering includes quenching and high-temperature tempering. Quenching temperature is 800-900℃, held for 30 minutes, and oil-cooled; high-temperature tempering temperature is 600℃, tempering time is 2 hours, and water-cooled.
3. Roughing on a CNC Machine Tool: Roughen the main and auxiliary shafts, leaving a machining allowance of 2.0mm on each side.
4. Deep Hole Drilling: Machining the inner hole to a diameter of 28mm-27.7mm.
5. Aging Treatment: Perform aging treatment on the entire main rotor shaft at 300℃ for 16 hours, followed by natural cooling and hoisting.
6. Spline Machining: Insert the auxiliary shaft into the main spindle and perform spline machining on the deep teeth of the main spindle using an external cylindrical grinder.
7. Nitriding Treatment: After spline machining, nitrid the auxiliary shaft and main spindle at 500℃ for 12 hours to achieve a surface hardness of 60-65 HRC and a nitriding depth of 0.15-0.3 mm.
8. Chrome Plating: Insert the auxiliary shaft back into the main spindle and chrome plating all external surfaces except the splines and inner bore surfaces. The chrome plating thickness is 0.04-0.06 mm.
### Precautions:
1. Equipment Inspection: Before machining, check that the moving parts are full of lubricating oil. Start the machine and check that the clutch and brake are normal. Let the machine idle for 1-3 minutes. Do not operate the machine if it malfunctions.
2. Operator Status: Maintain a correct working posture and have sufficient mental fortitude to work effectively. Operators must not operate the machine when agitated or fatigued to prevent accidents and ensure safe operation.
3. Die Replacement: Power must be switched off before changing the die. Die installation and adjustment can only begin after the stamping department has stopped operating. After installation and adjustment, manually move the flywheel twice to check the symmetry and proper fit of the upper and lower dies, the tightness of the screws, and the correct position of the blank support.
4. Work Area Cleanup: Before starting the power, wait for all other personnel to leave the machine’s work area and remove any debris from the worktable. Do not place your hands within the working area of the slide block while the machine is operating, and never use your hands to grab or place workpieces.
5. **Abnormal Handling:** If any abnormal noise or malfunction is detected, immediately switch off the power and inspect the machine.
6. Machining Accuracy: The motor shaft requires high machining accuracy. Dimensional accuracy and cylindricity must be carefully controlled to ensure smooth assembly and reliable operation.
7. Surface Roughness: Low surface roughness of mating surfaces leads to easy wear and loosening of the mating parts. Insufficient surface roughness on non-mating surfaces will reduce the fatigue strength of the shaft.
8. Shoulder Treatment: The fillets and wheel runout grooves at the shaft shoulder must be machined to the specified dimensions to ensure shaft strength and smooth end-face contact of mating parts.
9. Keyway Symmetry: The symmetry of the keyway relative to the axis of the reference surface should not exceed the tolerance; otherwise, assembly difficulties will occur.
10. Bearing Spacing: The distance between the two bearing spacings must be accurate; otherwise, axial misalignment of the rotor core or bearing jamming after assembly may occur.
The above are the machining methods and precautions for UAV motor shaft cores. Following these steps and precautions can ensure the machining quality and performance of the motor shaft core.
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