There are processes of turning smooth stop and inner circle of smooth stator core when machining motor base. In order to make the air gap of the motor even, the iron core is pressed into the motor seat. In general, the method of finishing turning the stop or the inner circle of the iron core is adopted to make the stop at both ends of the motor seat and the inner circle of the iron core coaxial. Today, from a theoretical point of view, we will make a simple analysis of the finishing of the core after pressing into the motor base.

External pressure assembly process theory
The stator core assembled by external pressure is positioned and superimposed on the inner circle, and the manufacturing errors of stamping sheets are reflected on the outer circle. Therefore, it is difficult to control the coordination between the outer core and the motor base. When the iron core is pressed into the motor base, it is easy to cause eccentricity due to too loose fitting, or the motor seat may be deformed due to excessive tightening. In order to eliminate this deformation, the coaxiality between the ends of the motor base and the inner circle of the iron core is ensured. Generally, the inner circle of the core is used as the reference position, and then the two ends of the stop are finely turned.

When finishing turning small motor seat stop on horizontal lathe, the fixture used is a typical structure of automatic centering. Expansion consists of three conical flaps, each end of which is covered with a rubber ring to prevent each piece from dispersing. The expansion tire and the mandrel are conical. When the nut is tightened, the expanding tire is pressed to the left, which forces the expanding diameter to increase, clamps the workpiece, and aligns the axis of the inner circle of the core with that of the central axis. Therefore, the stop of finish turning is coaxial with the inner circle of the core. When a special n-shaped tool rod is used and one knife is clamped at each end, the finish machining of the two end stops can be completed successively under the condition of one clamping of the workpiece. That is to say, one end of the stop is turned with one knife, and the other end of the stop is turned with another knife. When turning the stator stop, the iron filings should be prevented from entering the winding ends to avoid damage to the windings. Therefore, a protective cover and a protective winding end are used in the fine turning of the opening.

If a vertical lathe is used to finish turning a stop, after turning one end of the stop, the spindle and the stator must be clamped together, and then the other end of the stop is turned. In this way, not only is the efficiency low, but it is also possible to cause different axes at both ends due to two clamping.
Different axis cause analysis
The method of fine turning the mouth with the inner core of the core is more commonly used in the manufacture of small asynchronous motors. However, the problem of different axes is still prone to occur, the main reasons are:
● There are many matching links between the inner core of the iron core, the expanded tire, the mandrel and the machine tool, and the fixture is worn or improperly clamped.
● The inner circle of the iron core is not neatly laminated, and the individual parts are prominent, which affects the correctness of the inner circle positioning reference surface.
● During the process of the energy line and the grooved mold, the tip of the core is deformed by force (partially protruding), so that the inner circle and the expanded tire cannot be dense.
● After the stator is dipped, the thickness of the paint film on the inner ring of the core is not uniform, or the paint slag adheres to the inner circle, resulting in the positioning of the expanded tire.
● When clamping, the contact surface is not completely cleaned, and gray dust is mixed in the middle of the contact part.
●  Individual groove moulds protrude grooves, resulting in inaccurate positioning of tire expansion.

Internal pressure assembly process theory
The inner core of the stator core is formed by laminating the punching piece into the machine base. The outer circumference of the punch is close to the inner wall of the base. When the core is laminated, the outer circumference of the punch is positioned. The manufacturing errors of the punch are reflected on the inner circle of the core. If the error exceeds the allowable value, the inner circle of the core must be turned. When turning the inner circle, the end and end faces of one end of the base are positioned; Since the core is made up of sheets, the amount of the cutter cannot be larger than the thickness of one sheet, and the cutting speed and the depth of the knife should not be too large, so as to prevent the stress from being too large to damage the sheet. If the inner circle is finely ground after the wedging is applied, the winding should also be protected to prevent the chips from sticking into the insulation. If the inner circle is finely ground before the welt, the core groove is empty at this time, and it is easy to reverse the teeth during cutting. In order to prevent the tooth from being reversed, the hardwood pin wedge should be inserted into the groove first, or the toothed portion should be clamped with the splint and then turned.

In order to simplify the process, the inner circle is finely ground for the stator with a small tooth width by using the ruled dipping paint. For the stator with a large tooth width, the inner circle is finely ground before the welt. In the past, the inner circle of the stator core was ground by a small grinding wheel on the lathe tool holder instead of the car. Side teeth are less likely to occur during grinding, but the iron loss is increased and the processing is not as convenient as before the car. It is rarely used.