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Main processes of motor manufacturing
1. Punching process
After the positioning holes are punched on the square silicon steel sheet, the outer diameter of the stator punching sheet is sheared on the circular shearing machine. This method is highly efficient, can cut a large diameter range, and has high punching accuracy (roundness, coaxiality); the tool structure is simple, and it is easy to sharpen and assemble and disassemble.
2. Stator core process
The stator core is stacked using a cylindrical tire structure with a full cylinder. The roughness of the cylindrical working surface is required to be high, generally above 3.2μm, and the coaxiality with the axis is generally below φ0.05mm. A keyway is also machined on the cylindrical surface. When stacking, a long key is inserted in the slot to match the slot width of the punching sheet to ensure that the stator slot is not skewed. After stacking, the center holes at both ends of the tire mandrel are used for positioning, and the outer circle of the core is turned on the lathe to the required size, and the machining allowance is generally 0.5-1mm (diameter).
There are two purposes:
One is to further improve the coaxiality of the "effective size" of the inner and outer diameters of the core.
Second, it effectively improves the contact between the core and the base to improve the heat conduction and heat dissipation of the base, reduce the operating temperature of the motor, and extend the thermal aging life of the insulation.
3. Stator with winding into the base
For motors above H355, all adopt the hot-sleeve stator process. Some hang the stator into the base, and some hang the base to cover the stator. Generally, the former is more common. The base is heated to 120-150℃ and kept warm for about 3 hours. This method can prevent the stator with winding from being crushed, and does not require a large-sized press.
4. Rotor
The cast aluminum rotors of small and medium-sized motors mostly adopt the horizontal high-pressure cast aluminum process, and the aluminum is fed from the inner side of the rotor end ring. The rotor end face is completely formed by the mold, without process cuts, very smooth, and the equipment has a high degree of automation. Smaller rotors can be die-cast 3 at a time.
The method to achieve the inclination of the copper bar rotor slot is to process the lamination keyway on the shaft to have a certain angle with the axis. When laminating, install a long key in the keyway, and then install the sheet on the shaft. The slot slope is formed when laminating. It should be noted here that the slope of the shaft keyway is the converted value of the rotor slot slope.
This slot slope is an approximate value. The rotor slot has a very slight spiral, but practice has proved that it can meet the design and process requirements, and does not require special tooling and equipment. It is a "zero cost" method.
When inserting copper guide bars, put the rotor on the roller frame. First, hold the guide bar and insert it every other slot, push it in about 100mm, insert 3-5 bars continuously, and then use a pneumatic tool to drive it in. At this time, the head of the guide bar is covered with a pad that fully matches the head to prevent the impact force of the pneumatic tool from injuring the head of the guide bar. After inserting half of the rotor slots, insert the other half of the slots.
This method is different from slot-by-slot insertion. The condition of the guide bar in the rotor slot is much better and the uniformity is good.
After the copper bar rotor is finely turned on the outer circle, the slots are all chipped and blocked. In this case, a handheld electric rotary file is used to clean them. This is efficient, and the slots are neat and the chamfers are obvious. Some rotors are not turned on the outer circle because the rotor punching has left an air gap.
Rotor dynamic balancing is generally performed at the rated speed. The dynamic balancing machine is intelligent and has a protective cover.
5. Double cooling structure of the base
In some occasions where the power is large and the volume is limited, the motor generally adopts the "air-water" cooling structure. The base cylinder is a three-layer structure, and the inner two layers are water circulation cooling channels. The outer layer forms an air duct, and the heat flow in the inner cavity of the motor enters the air duct, which is cooled by water and dissipated through the outer cover cylinder.
6. Slip ring group structure
The slip ring group of the wound rotor has three major characteristics:
(1) There are spiral grooves on the slip ring, which are used to flatten the brushes and always maintain good contact with the slip ring.
(2) A large-diameter fan is installed at the outer end of the slip ring group for cooling and cleaning.
(3) The rotor lead terminals are sealed with dust covers to isolate them from brush dust and prevent creepage from causing faults.
7. Assembly of the motor
The motor assembly needs to be extremely careful, and all the parts used for assembly must be visually inspected. The workers consciously and strictly abide by the mandatory inspection items and make very careful records. The following operations and self-inspection items need to be paid attention to:
(1) If the primer surface of the parts is peeling or uneven, it should be re-brushed.
(2) If the bolt is not screwed in smoothly, the screw hole needs to be reamed once with a tap.
(3) If minor scratches are found on the non-important surface of the parts, they need to be repaired.
(4) No matter how big the bolts and nuts are, there are standards for tightening torque (N.m).
(5) For bearing structures with oil drainage, grease must be filled.
(6) Check the shaft runout with a micrometer and the shaft diameter with a through gauge.
(7) Check the outer diameter runout of the bearing with a micrometer.
(8) Check the alignment of the stator and rotor ventilation sections.
A careful and meticulous work attitude, clear and specific technical requirements, and standardized operating procedures are necessary conditions for completing motor manufacturing. Ningbo Nide Mechanical Equipment Co., Ltd, adhering to the customer-centric concept, focuses on the stator, rotor and complete assembly of various motors, and provides customers with one-stop solutions for highly automated, intelligent and flexible production. After years of development, NIDE has gradually accumulated a certain influence and brand effect at home and abroad. At present, the products cover the professional manufacture of new energy motor stator and rotor, hairpin motor, automatic aluminum casting rotor line, brushless motor/ BLDC motor, universal motor, wheel hub motor , etc., which are used in new energy vehicles, household appliances, industrial motors, water pump motors, servo motors, etc. The company integrates R&D, production and sales, and wholeheartedly serves customers at home and abroad, aiming to deliver value and achieving a win-win situation.