Popular Nema 17 Closed loop stepper with new stocks
All kinds of mechanical vibration produced by the motor in operation will wear and corrode the coil insulation, the most important of which is electromagnetic vibration, which affects the insulation of the motor end winding and notch. If the pressing quality of stator core is not good, and the winding end binding process is not good, the coil will slip in the slot, and the interlayer gasket and the temperature measuring element gasket will move back and forth between the upper and lower coils, which will wear the upper and lower coils and damage the coil insulation. What’s more, if the coil is running, the current passing through the wire will generate two times of electromagnetic vibration force, which will not only make the coil vibrate with the spacing block at the end of the iron core and the winding, but also cause friction vibration between the wire and the insulation, between turns and strands of the wire, resulting in loose winding turns and strands, short circuit, disconnection and other problems. At the same time, additional loss occurs at the short-circuit part, which causes the local temperature of the winding to rise sharply, the insulation strength to decrease, and the insulation breakdown fault occurs. Therefore, electromagnetic vibration is the main cause of coil insulation damage.
The composition of insulation materials, laminated cores, coil wires and other parts used in the motor makes its structural rigidity and conditions of thermal expansion and cold contraction during operation more complicated, which is one of the reasons for motor vibration. The unbalance of the rotor, the electromagnetic force in the motor, the torsional impact of the motor after dragging the load, and the impact of the power grid will all lead to the vibration of the motor.
Vibration of the motor is harmful, for example, it will bend and break the rotor of the motor; Make the magnetic pole of the motor rotor loose, resulting in the motor stator and rotor rubbing and bore sweeping failure; To some extent, it will accelerate the wear of motor bearings and greatly shorten the normal life of bearings; The motor winding ends are loosened, resulting in friction between the end windings, reduction of insulation resistance, shortening of insulation life, and even insulation breakdown in severe cases.
The main parts that affect motor vibration include motor stator core, stator winding, motor base, rotor and bearing. The vibration of stator core is mainly caused by electromagnetic force, which produces elliptical, triangular, quadrilateral and other vibration modes. When an alternating magnetic field passes through the stator laminated core, it will produce axial vibration. If the core is not pressed tightly, the core will produce violent vibration, which may even lead to broken teeth. In order to prevent this kind of vibration, the stator core generally adopts pressing plate and screw compression structure, but at the same time, attention should be paid to prevent the damage caused by excessive local pressure of the core.
During the operation of the motor, the stator winding is often affected by the acting force of the current and leakage flux in the winding, the magnetic pull of the rotor, the thermal expansion and contraction force of the winding, etc., which causes the system frequency or double frequency vibration of the winding. When designing a motor, it is particularly worth considering the vibration of the slot and top of the stator winding caused by electromagnetic force. In order to prevent these two kinds of vibration, it is often necessary to take measures such as the fastening structure of the groove bar and the axial rigid bracket at the end.