Reduce the temperature rise of the motor, must control the key process
The temperature rise level is an important indicator related to the reliability of the use of motor products. If the motor temperature rise test value is too low, it means that the effective material consumption is too high, the manufacturing cost is increased; the test value is too high, the motor is easy to overheat under normal working conditions, the winding insulation is prematurely aged, and the aging is severe to a certain degree, directly burning the motor .
In fact, one of the important goals of motor design is to control the temperature rise in a certain range as a prerequisite, and the material consumption is as small as possible. Here MS. Participate in personal work experience, talk about specific measures to reduce temperature rise in the motor manufacturing process. Assuming that the design parameters have been optimized to an optimum state, the decisive factor affecting the temperature rise of the motor depends on the manufacturing process level.
The manufacturing process affects the temperature rise factor
Winding dipping paint
The dipping paint not only strengthens and solidifies the insulation of the motor, but the impregnating varnish fills the air gap between the winding turns and the windings to the ground through advanced vacuum pressure dipping equipment. Since the thermal conductivity of the insulating impregnating varnish is much greater than the air, all the heat generated by the loss in the stator winding of the motor is mainly transmitted to the iron core through the insulating layer of the winding, that is, the impregnating varnish, and the iron core directly transmits the heat to the motor casing.
If there is a problem with the pre-baking temperature of the motor, the viscosity of the paint and the time of dip coating, the paint loss will be severe during the drying process, the gap between the winding and the core groove will be filled, and the windings in the core groove will not be saturated. A large rise in the temperature of the winding is induced. For this reason, the quality control of the winding immersion process has a very important influence on reducing the temperature rise of the motor.
Stator core and frame
The mating surface of the stator core and the base is an important way to conduct heat of the stator winding and heat loss of the core. If the stator core and the base are tightly fitted together, the resistance to heat transfer between the two cores is greatly reduced, and the core temperature is lowered. Various defects often occur in the manufacturing process: data deviation and rough processing of the diameter of the crucible in the frame; the stator core is not laminated; when the paint is immersed, the residual paint layer on the outer surface of the core is too thick.
In addition to seriously affecting the stator and rotor coaxiality of the motor, the other fatal defect caused by the increase is that the gap between the stator core and the base increases, resulting in an increase in thermal resistance, which makes the motor heat-dissipating difficult, resulting in an increase in winding temperature.
Base surface treatment
When the heat loss generated inside the motor is transmitted to the surface of the machine base, it is mainly carried by the fan end through the surface air of the motor. Therefore, in order to effectively control the temperature rise of the motor, the heat dissipation level of the surface of the base should be increased as much as possible, so that the iron casing with strong thermal conductivity and the air of the cooling medium should be as close as possible to the air, or the isolation layer should be as thin as possible.
This situation must be paid special attention, because each motor manufacturer attaches great importance to the apparent quality. In order to look good, the flattened putty and paint layer are thicker, which does make up for the surface defects of the shell, but it affects The actual heat dissipation performance of the base surface.
Motor fan compliance
The fan is the main wind pressure component of the self-fan cooling motor, and its size and shape are the key factors determining the temperature rise level. If the blades of the mixed-flow fan with strong volatility are accidentally collided or heavily pressed during bending and deformation during stacking and handling, the corner and impact angle of the fan are changed, which will inevitably lead to an increase in the temperature rise of the motor winding.
From the design point of view, there are certain differences between the fans of different pole motors with the same height. If the fan is misused, the ventilation and heat dissipation effect will be greatly reduced; if it is misused as a large fan, it will lead to the deviation of the motor efficiency index. .
Fan blades with two-way rotation or rotation uncertainty are generally not directional, but for a motor with a fixed rotation, the direction of the blade must be guaranteed.
Punch quality control
Core loss is one of the five major losses of the motor. The quality of the punch must be strictly controlled to ensure the stacking factor. Mainly controlled from the following three aspects:
Punching material. On the one hand, this requirement lies in the choice of the silicon steel sheet supplier to ensure that the material properties are met; on the other hand, it is also necessary to prevent the material use grade from meeting the design requirements. For example, the silicon steel sheet of W600 should be misused as W800.
Punch burr control. Most iron core manufacturers can control the punching burr within 0.05mm, which can ensure the laminated effect of the iron core; otherwise, the effective iron weight will be insufficient, the core eddy current will increase, and then the iron loss and temperature rise will increase. .
Iron core laminated. After the iron core is laminated, it tries not to rub, does not grind, does not process and does not damage the insulating oxide film. This problem exists in many motor manufacturers. Each motor manufacturer should make substantial improvements to this problem, because the repair of the core manufacturing process will directly affect the performance of the motor. The machining process, motor quality control and improvement will not be very good.
Purity and parameter control of cast aluminum rotor aluminum
For aluminum for cast aluminum rotors, on the one hand, the procurement quality control of aluminum, on the other hand, it has a direct relationship with the aluminum melting process in the aluminum casting process. Some enterprises use ceramic tongs to ensure the purity of aluminum in the process of casting aluminum. However, some companies use cast iron tongs. In this way, aluminum is cast. In each batch, there are always some rotors using the last aluminum in the pot. When the liquid is in poor purity, the direct resistance of the motor is high. The reason is that the iron content exceeds the standard and the leakage magnetic flux increases.
The process parameters of rotor cast aluminum mainly include core preheating temperature, aluminum liquid temperature, pouring speed, centrifugal casting speed and pressure, etc. These parameters of different motor manufacturers have certain differences, and are also relatively key and confidential control parameters of the manufacturer. Ms. participated in a low-pressure cast aluminum enterprise. The company has excellent equipment and the rotor casting quality is very good. However, a high level of confidentiality measures have been taken for the process parameters of the process, and the visitors are not able to see the specific content.
Rotor cast aluminum defect control
The broken bar inspection device is used to check whether the rotor has defects such as thin strips, broken strips, shrinkage holes, shrinkage and pores. For a rotor with a serious rotor defect, the rotor will exhibit a pronounced blue phenomenon when the motor is running, and the more severe rotor aluminum melts out.
Motor manufacturing is an excellent manufacturing process. The same design is produced by different motor manufacturers, and there will be very different effects. Different motor manufacturers have their own unique advantages in different process links. The advantage of doing motor quality is the call for the quality of motor products under new market conditions.
Please pay attention to Mini Gear Motor
