Briefly analyze several methods of holding magnetic steel
The inside of the casing of the motor is a smooth curved surface. The bonding of the magnetic steel is very difficult. The magnetic pole of the motor is subjected to a relatively large peeling force at the moment of magnetization, and the shearing force is mainly used during operation. So if the magnetic tile does not loose when magnetizing, generally does not loose or fall off after the operation.
According to different shapes of magnetic steel, different holding methods can be used. Now there are generally the following methods: mechanical holding method, adhesive holding method, mixed holding method, and the following is a brief introduction.
First, mechanical holding method
This method is used in many ways, such as toy motors, hair dryer motors, etc. The advantage of this method is that it is easy to install and saves material, but it can only be used for small motors. Larger, higher precision motors generally use the following scheme.
This method changes the wire circlip of the small motor into a steel plate circlip, so that it can jam the relatively large magnetic steel so that it cannot move, but such a circlip also has the following disadvantages.
1, the circlip installation must be loaded with tooling, and it is more laborious.
2. Since the two poles are connected to the circlip, a part of the magnetic lines of force are short-circuited directly by the circlip, and the effective magnetic flux of the motor is reduced by about 10%, which is very disadvantageous to the performance of the motor.
This method is often used on the flywheel of the generator, but two pole pieces must be added. The magnetic flux of the magnetic steel is reduced, so the magnetic flux of the whole motor is reduced, and the processing of the magnetic steel is difficult.
Second, the adhesive holding method
Nowadays, the method of holding tile-shaped magnetic steel often adopts the bonding method at home and abroad, which is convenient and economical, and the processability is also good, but brings about the question of what kind of glue is used, whether it is firm or the like.
The outer arc surface of the magnetic tile and the inner arc surface of the casing cannot reach a complete anastomosis. If the outer diameter of the magnetic steel is smaller than the diameter of the casing, the contact between the two aspects is unstable, if the outer diameter of the magnetic steel is larger than the diameter of the casing, and the contact between the two faces is stable.
Therefore, from the on-site analysis of the magnetic tile falling off, it can be seen that the most serious one is only three points of contact, which only accounts for one-fifth of the area to be bonded. The rest is not well combined. If a little external force is applied, it will fall off. If the viscosity of the adhesive is too low, it will also result in weak bonding.
Therefore, whether the rigidity of the adhesive itself can exert a certain degree of filling effect must be considered carefully.
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