Permanent magnet motors are widely used in many fields because of their high power factor and high efficiency. Permanent magnet motors generally install magnets on the rotor to ensure the reliability of the electrical connection of the stator. Its structural types are:

Embedded magnetic steel – the rotor punching is punched with a magnetic steel groove, and the magnetic steel is installed in the groove, because the symmetry of the magnetic steel groove has been fully guaranteed during the manufacture of the punching sheet, thereby ensuring the symmetry of the magnetic circuit;

Magnetic steel bonding type – stick the magnetic steel on the yoke with a special adhesive; rely on the process to ensure that the magnetic steel is uniform so that the magnetic circuit is symmetrical; the bonding is firm so that it will not be disengaged at a large linear speed.

In addition to general manufacturing processes (such as mechanical, thermal, and electric clamp processes), there are several key processes in the manufacture of permanent magnet motors:

(1) Due to the strong adsorption force of the magnetic steel, it is very easy to adsorb when it is close to ferromagnetic materials (such as iron cores, rotating shafts, etc.).

When the rotor is assembled, the assembly gap between the magnetic steel and the rotor magnetic steel groove is only about 0.1mm. When the magnetic steel is close to the rotor core, the strong adsorption force will directly adsorb the magnetic steel to the iron core and it is difficult to fit into the groove; That is, it is difficult to separate again, and the assembly is extremely difficult and has certain dangers.

(2) If there is no strong and accurate guidance guarantee for the rotor during final assembly, the stator and rotor will be attracted and locked by strong magnetic force, making it difficult to separate, resulting in failure of final assembly.

The following is the key manufacturing process of permanent magnet motor magnet assembly and general assembly.

1. Magnetic steel assembly process of the rotor

1.1 Process points

When assembling the magnetic steel, try to overcome the strong magnetic attraction of the magnetic steel to the rotor core to ensure smooth assembly, and the polarity of the magnetic steel is correct to ensure the symmetry of the magnetic circuit. To this end, a detailed process test was carried out, the process plan of magnet assembly was determined, the magnet assembly tooling and guide fixture was designed, and the polarity of the assembled magnet was qualitatively analyzed by reasonable means. The relative magnetic flux value of each slot magnet was close to, that is, to ensure the symmetry of the magnetic circuit to ensure the assembly quality of the magnetic steel.

1.2 Process

(1) In order to ensure the accuracy of assembly, design fixtures.

(2) Carry out magnetic steel separation, polarity label inspection, and relative value inspection of magnetic flux to ensure that the magnetic flux of each pole is equal after assembly. At the same time, conduct a visual inspection to see if there is any damage. Although the permanent magnet materials of various brands have standards to guarantee their basic performance, the enterprise standards of each factory are different, and the permanent magnet materials of the same brand are produced in the same factory even if they are produced in the same factory. Magnetic materials vary in performance. Therefore, the above inspection work is very important. A motor should be equipped with the same batch of magnetic steel to ensure the electromagnetic performance of the motor.

(3) Preparation of the work site: Enclose the rotor assembly work site with non-magnetic guardrails, and give clear warnings at eye-catching positions; clean the work site, clean all corners of the site with high-pressure air, no iron filings, welding Ferromagnetic waste such as slag; prepare non-magnetic fixtures, stainless steel non-magnetic wrenches, partitions, wooden supports, copper hammers, 3240 glass cloth panels, etc.

(4) Blow off the stacked rotor with high-pressure air, and wrap it with white cloth to prevent other impurities and waste during transportation; support the rotor well (make the rotor horizontal), and check the rotor on the sample again. Magnetic steel groove, and then fix the protective tooling fixture on the rotor, ready to install the magnetic steel.

(5) Every two magnets are separated by a non-magnetic plate with a thickness of about 15mm, and the polarities of “N” and “S” are marked on the two large surfaces (working surfaces) of each magnet, and clearly Write the relative value of the magnetic flux. Magnets with the same value are basically placed together for easy assembly. Separate the magnets by hand on the wooden support.

Note: Please do not operate with two magnets. Once they are adsorbed together, they cannot be separated, and the two magnets are very easy to hurt people during the adsorption process, which is very dangerous. The operator is required to assemble the magnetic steel piece by piece during the operation. Keep the magnetic steel away from the ferromagnetic material, and then put it into the magnetic steel guide tooling, and align it with the magnetic steel groove on the rotor. At this time, attention should be paid to the assembly polarity of “N” and “S” of the magnet and the relative value of the magnetic flux of the magnet. When assembling, do not fill all the magnets in one rotor slot, but first install one or two magnets in the entire rotor slots, until the final assembly is complete. During assembly, if a piece of magnetic steel is not assembled in place, you can use a copper rod or a non-magnetic hard rod to push the magnetic steel into place. Note: Don’t use too much force, so as not to knock and damage the magnetic steel.

• Check the polarity of the magnetic steel by aligning the compass with each groove of the outer circle of the rotor. After the polarity is qualified, assemble other fixing parts; then wrap the whole rotor with white cloth and prepare to flow into the next process.

2. Assembly process

2.1 Process points

The overall adsorption force of the rotor equipped with magnetic steel is very strong, and the air gap between the stator and the rotor is small. During the assembly, it is easy to cause the collision between the stator and the rotor due to the strong gravitational force, which may cause the stator and the rotor to be adsorbed together and difficult to separate. Even scrapped, and easy to cause personal injury. The traditional vertical or horizontal assembly process can no longer meet the requirements, so the final assembly is the key to the process under the condition that the stator and rotor are absolutely concentric.

2.2 Process

(1) Design a non-magnetic dummy rotor, and use the dummy rotor to correct the frame;

(2) Install end cover and permanent magnet rotor;

(3) Final assembly.

The designed permanent magnet motor technology adopts non-standard equipment such as fake rotor and final assembly machine, and is tested on the motor developed by Eneng. The final assembly process is strong and the operability is reliable. At present, the general assembly process of this type of motor is in the leading position in the domestic similar motor production industry, which enables our factory to maintain the leading technology in the domestic energy-saving submersible motor field and expand new markets rapidly.

In addition, through a period of production exploration, the design supplemented some tooling, such as the use of false rotor tooling for orientation and positioning before the general assembly, and improved the process method, which increased the production efficiency by about 2 to 3 times.