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Precision rotation method of motor stop port and core inner circumference by horizontal lathe

Precision rotation method of motor stop port and core inner circumference by horizontal lathePrecision rotation method of motor stop port and core inner circumference by horizontal lathe

When machining the motor base, there is a process of smooth stopping and turning the inner circle of the smooth stator core. Push the iron core into the motor seat to even out the air gap of the motor. Generally, in order to make the stop portions at both ends of the motor seat coaxial with the inner peripheral portion of the iron core, a method of rotating the stop portion or the inner peripheral portion of the iron core to finish is adopted. Today, from a theoretical point of view, we will briefly analyze the finish of the core after it has been pushed into the motor base.

External pressure assembly process theory

The stator cores assembled by external pressure are positioned and overlapped in the inner circle, and the manufacturing error of the stamping sheet is reflected in the outer circle. Therefore, it is difficult to control the adjustment between the outer core and the motor base. If you push the iron core into the motor base, it will easily become eccentric if it is overtightened, and if it is overtightened, the motor seat may be deformed. In order to eliminate this deformation, the coaxiality between the end of the motor base and the inner circumference of the iron core is ensured. In general, after using the inner circle of the core as the reference position, rotate both ends of the aperture finely.

When finishing turning a small motor seat stop on a horizontal lathe, the fixture used is typical of automatic centering. The extension consists of three conical flaps, each end covered with a piece of rubber to prevent each piece from falling apart. The expansion tire and mandrel are conical.
Tightening the nut pushes the expanding tire to the left, which increases the expanding diameter, tightening the workpiece and aligning the axis of the inner circle of the core with the axis of the central axis. Therefore, the stop of finish rotation is coaxial with the inner circle of the core. Using a special n-shaped tool rod and tightening one knife at each end, the finishing of two end stops can be completed in succession under the condition of one tightening of the workpiece. That is, one end of the stopper is rotated by one knife and the other end of the stopper is rotated by the other knife. When turning the stator stopper, it is necessary to prevent the iron file from getting into the end of the winding to avoid damage to the winding. Therefore, a protective cover and a protective winding end are used for minute rotation of the opening.

If you use a vertical lathe to end the rotation of the stop, you must rotate one end of the stop, then secure the spindle and stator, and then rotate the other end of the stop. In this way, not only is it less efficient, it is also possible for the two clamps to cause different axes at both ends.
Different axis cause analysis

The method of finely rotating the mouth using the inner core of the core is more commonly used in the cnc manufacture of small asynchronous motors. However, the main reasons why problems with different axes are still prone are:

  • ● There are many matching links between the inner core of the iron core, the expanding tire, the mandrel, and the machine tool, and the fixture is worn or improperly fixed.
  • ● The inner circles of the iron core are not neatly laminated, and individual parts stand out, which affects the correctness of the inner circle positioning reference plane.
  • ● During the processing of energy lines and grooved molds, the tip of the core is deformed by force (partially protruding), and the inner circle and the expanded tire cannot be dense.
  • ● After immersing the stator, the thickness of the coating film on the inner ring of the core is uneven, or the paint slag adheres to the inner circle, so the expanded tire can be positioned.
  • ● When clamping, the contact surface is not completely cleaned and gray dust is mixed in the center of the contact part.
  • ● Since each groove type has a protruding groove, the expansion position of the tire will be inaccurate.

Internal pressure assembly process theory

The inner core of the stator core is formed by laminating punched pieces on a machine base. The outer circumference of the punch is close to the inner wall of the base. When the cores are stacked, the outer circumference of the punch is positioned. Punch manufacturing errors are reflected in the inner circle of the core. If the error exceeds the tolerance, you need to rotate the circle inside the core. Rotating the inner circle aligns the end faces and end faces of one end of the base. Since the core is made up of sheets, the amount of cutter cannot be greater than the thickness of one sheet, the cutting speed and the depth of the knife should not be too high and stress too high. is not it. It will damage the alloy sheet. If the inner circle has been finely ground after the wedge has been applied, the windings should also be protected to prevent chips from sticking to the insulation. If the inner circle is finely ground before welding, the core groove is empty at this point and it is easy to flip the teeth during cutting. To prevent the teeth from flipping, you need to insert the hardwood pin wedge first into the groove or fix the toothed part with a splint and then rotate it.

To simplify the process, the inner circle is finely ground for stators with small tooth widths by using a lined immersion paint. For wide toothed stators, the inner circle is finely ground before welding. 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 they increase iron loss and are not as convenient to process as in front of the car. Rarely used.