The motor shaft is a cylindrical part protruding from the motor and its casing. The shaft is the main support and connection part of the armature part of the motor, and is also the output part of the power generated by the motor. The purpose of the shaft is to convert the electrical energy of the motor into kinetic energy. , Precision pins and motor shafts are used to provide the speed and torque of the motor, and are one of the indispensable and important parts in the motor. Simple shafts are commonly used in motor applications such as power steering control systems, small appliance motors, power tool motors and specialty components. The unreasonable design will lead to insufficient shaft radius, and the stress concentration generated by the change of installation position may lead to catastrophic failure of the shaft after a very short service life, so the shaft needs to meet certain technical requirements.

strength and stiffness

When the motor is running, the form of mechanical force and torque on the shaft varies with the type of motor and transmission mechanism. The acting forces mainly include: the gravity of the rotor assembly itself, the one-way magnetic pull caused by the eccentricity of the rotor, the centrifugal force of the unbalanced weight, and the load torque acting on the shaft by the transmission machinery at the shaft extension end. Therefore, the shaft of the motor must first have enough strength to ensure that the motor does not have residual deformation or damage during the working state and processing. Within the allowable range, the critical speed of the shaft should also be considered, and there should be enough difference between the working speed of the shaft and the critical speed to prevent resonance, especially for motors with high speeds, if necessary Calculation of critical speed.

In the manufacturing process of surface hardness, the shaft often collides with the assembly mold. In the punching, beer positioning ring and other processes, there is a certain amount of assembly interference. The hardness of the shaft is higher than the positioning ring and the chip material. A certain difference, Only then can it be ensured that the shaft surface will not be scratched or wound during assembly. On the other hand, if the bearing is to be installed on the shaft, the surface hardness of the shaft must be controlled to be no higher than HV450. For rolling bearings, the requirements for the surface hardness of the shaft can be appropriately relaxed, and surface heat treatment is generally not performed.

Surface roughness is a very important surface quality control parameter. If it is a sliding bearing, too high surface roughness will directly destroy the oil film on the contact surface, thus greatly increasing the wear of the bearing, but too low surface roughness will cause the shaft to Molecular friction, which forms between the bearings, is also detrimental. Therefore, the scope of our control is different depending on the materials used and application conditions, and the scope of control has also changed accordingly. If it is a rolling bearing, when the surface roughness does not meet the requirements, the bearing section of the shaft will reduce the contact surface of the inner circle of the bearing and loosen the fit, causing the bearing to rattle and make noise. The shaft extension will directly affect the connection accuracy with the load device, easily causing vibration and noise. The iron core section will cause the change of the air gap between the stator and the rotor and the flatness of the chip arrangement, which will affect the performance of the motor and the difficulty of chip winding. .

Straightness (T.I.R.)

If the straightness of the overall shaft body does not meet the requirements, it will cause unbalance in the shaft core section, causing the motor to vibrate, and in the bearing section, the contact surface between the shaft and the bearing will be inclined, resulting in a defective motor with low speed and high current. Shaft extensions can cause vibration and noise in the connection. In short, the straightness of the shaft is also the basic condition for the normal operation of the motor. In special environments, the material of the shaft is required to have certain corrosion resistance.

in conclusion:

In the manufacturing process of the shaft, the straightness of the shaft must be controlled to meet certain requirements. This requirement comes from two aspects: one is the requirement for the transmission accuracy of the application device; the other is the requirement for the normal operation of the motor itself. The requirement for the transmission accuracy of the application device comes from the user's accuracy according to the application device, and the requirement for the normal operation of the motor itself is obtained according to the comprehensive consideration of the matching clearance between the shaft and the bearing of the motor, the vibration of the motor, the noise of the motor, and the performance requirements of the motor. the result of.