JPS5925554A - Manufacture of rotor - Google Patents

Abstract

PURPOSE:To make the bearing section and load shaft section of a shaft concentric by inserting the shaft to a cast rotor, pressing the cast rotor in a ring and finishing-working the bearing section and the load shaft section while using an outside diameter of the ring as a reference. CONSTITUTION:The shaft 2' with the bearing section 2a' and the load shaft section 2c', finish clearances therefor are left, and a fitting section 2b' finishing- worked is inserted to the cast rotor 1, the size of an outside diameter thereof is finished through a punching process and which is casted, and the fitting section 2b' is fitted. The cast rotor 1 is pressed in the ring 6, inside and outside diameters thereof are worked concentrically. The bearing section 2a' and load shaft section 2c' of the shaft 2' are ground under the state in which the shaft is turned while using the outside diameter of the ring 6 as the reference.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a rotor of a rotating electric machine, particularly a small induction motor.

[Technical background of the invention and its problems]

For example, the rotor of an induction motor is made by fitting a shaft 2 as shown in FIG. 3 onto a so-called cast roll 1 as shown in FIG. 1 by press fitting or shrink fitting, as shown in FIG. 4. ing.

Conventionally, the bearing parts 2&, 2c and the load shaft part 2d of the Doi shaft 2 are subjected to a grinding process, and the fitting part 2b is subjected to a grinding process or a Lawson process to prepare a finished product. The cast rotor 1 is made by laminating a predetermined number of rotor punched plates 3 made of electromagnetic steel sheets punched into a predetermined shape, and then casted with a conductive member such as aluminum, and includes cooling blades 4 and an end ring 5. It has a structure in which slot bars are joined together. The rotor punched plate 3 has a hole 3b into which the shaft 2 is fitted and a thrower) Ja, as shown in an enlarged view in FIG.
The outer diameter is given by the Do dimension.

After the shaft 2 is fitted to the cast rotor 1, the outer diameter of the cast rotor 1 is turned from Do to D based on the ground parts 2ar to 2d of the shaft 2, and the cast rotor 1 is driven by an induction motor.

However, the above-mentioned method has problems with electrical accuracy as described below, vibration of the motor, noise generation,
Furthermore, the increase in surface loss causes a decrease in efficiency. This will be explained with reference to FIG. What is shown by a solid line in FIG. 2 is a rotor punched plate before being subjected to turning processing, that is, in a punched state. Po is the geometric center of the shaft hole 3b and the outer diameter Do, and D shown by a dashed line is the outer diameter after turning. Further, t is called a chip dimension, and is the distance between the tip and the top of the slot 3a obtained by turning.

When fitted with the shaft 2, the center of rotation during turning is completely aligned with Po due to factors such as deformation during the casting process of the cast rotor and concentricity of the bearing part 2b with respect to the bearing part 2a + load shaft part 2d of the shaft 2. They do not match and rotate at P', which is shifted by ε.

If turning is carried out at this P' and the outer diameter is machined to zero dimension, a difference in chip size of tl' to t'' will occur in the direction of deviation ε.

When expanded in the circumferential direction and shown in FIG. 5, this chip dimension becomes a sinusoidal curve. Although such a rotor is used, the chips are not uniform, resulting in periodic non-uniformity phenomena that reduce electrical accuracy and cause vibration and noise.

Further, since the outer diameter of the laminated rotor blanks 3 is machined by turning, a phenomenon in which the rotor blanks 3 are short-circuited to each other on the outer diameter surface of the rotor (bridge phenomenon) cannot be avoided. This causes stray loss on the rotor surface, causing a decrease in the efficiency of the motor.

In order to eliminate the latter problem, a so-called "no-external rotation method" has been proposed in which the outer diameter of the rotor punch plate 3 is punched to zero dimension at the time of punching, but since there is no external rotation, Due to the above-mentioned problem of fitting accuracy, in the case of fitting, gap accuracy becomes a problem. That is, a "runout phenomenon" of the outer diameter of the rotor corresponding to the deviation of ε occurs, which causes a periodic phenomenon of non-uniform gaps, which also causes vibrations and noise, which is an unresolved problem.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide an excellent electric motor that eliminates rotor surface loss using a non-external rotation system and that does not cause deterioration of motor characteristics due to gap runout. This is what I am trying to do.

[Summary of the invention]

The present invention involves inserting a shaft having a bearing part, a load shaft part with a finishing allowance, and a finished fitting part into a cast rotor whose outer diameter has been finished and cast in a punching process. After the fitting parts are fitted together, the cast rotor is press-fitted into a ring whose inner and outer diameters are machined concentrically, and the bearing part and load shaft part of the shaft are finished with the outer diameter of this ring as a reference. It is something to do.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on FIGS. 6 and 7. First, only the fitting portion 2b' of the shaft 2' into which the cast rotor 1 is fitted is turned, ground, or knurled to a predetermined size. A finishing allowance is left for the bearing parts 2a', 2c' and the load shaft part 2d' of the shaft 2' for finishing in a subsequent process. From this state, the shaft 2' is inserted into the cast rotor 1 and its fitting portion 2b' is fitted, and then the cast rotor 1 is press-fitted into the processing ring 6. This processing ring 6 is precisely finished so that its inner and outer diameters are concentric, and the thickness and hardness are such that the precision does not change. Therefore, the geometric center of the inner and outer diameters of the processing ring 6 and the center Po of the rotor blank 3 coincide.

The cast rotor 1 into which the processing ring 6 has been press-fitted as described above is then set in the processing device 12. This processing device 12 is composed of two driven bearings 7, 7 and one drive roller 8. The driven bearing 7.7 is made of hardened steel or the like that does not lose its precision, and the drive roller 8 is made of hard rubber or the like in order to drive it by friction with the processing ring 6. In addition, the drive roller 8
is engaged with a lever 10 which is driven by a drive source (not shown) and moves around a fulcrum S by the pressure of a cylinder 9.

When the cylinder 90 rod 9d is retracted, the row 28 moves upward, and the cast rotor into which the processing ring 6 is press-fitted is supplied from the left side in FIG. 7 and comes into contact with the driven bearing 7.7, and the rod 9d comes out and the drive roller 8 is driven with a constant pressure applied to the outer periphery of the processing ring 6, and the processing ring 6 rotates. Thereafter, the grinding wheel 11 is moved from the right side in FIG. 7 by a drive mechanism (not shown) to make a predetermined cut into the bearing portions 2a', 2c' and the load shaft portion 2d' of the shaft 2'. As a result, when the shaft 2' is finished to a predetermined size, the grinding wheel 11 returns to the right, the drive roller 8 moves upward, and the workpiece is removed. Thereafter, the workpiece is taken out from the processing ring 6.

As described above, the bearing portion 28' of the shaft 2' is rotated based on the outer diameter of the processing ring 6.

2c', in order to grind the load shaft part 2d', the outer diameter of the rotor is concentric with the bearing parts 2a', 2c', and 2d'. It is possible to supply an electric motor.

In addition, in the above-mentioned example, the processing ring 6 is used because
Since the outer diameter of the cast rotor 1 is formed by the laminated rotor punched plates 3 by punching, the microscopic irregularities of the sheared surface are transferred during the punching process during grinding of the shaft 2', thereby preventing grinding. The purpose is to prevent stability.

〔Effect of the invention〕

As explained above, the present invention provides a cast rotor whose outer diameter has been finished and cast in a punching process.
After inserting a shaft having a bearing part and a load shaft part with a finishing allowance left, and a fitting part that has been finished, and fitting the fitting parts, the cast rotor is made so that the inner and outer diameters thereof are concentric. The outer diameter of the rotor is concentric with the bearing part and the load shaft part because it is compressed into the processed ring and the bearing part and load shaft part of the shaft are finished machined based on the outer diameter of this ring. When operated as an electric motor, an excellent electric motor without gap runout can be provided. Furthermore, since the cast rotor is cast after finishing its outer diameter in a punching process, there is no stray loss on the rotor surface, and rotational efficiency can be maintained at a good level.

[Brief explanation of the drawing]

Figures 1 to 5 show conventional examples. Figure 1 is a perspective view showing a cast rotor, Figure 2 is a plan view showing rotor punching, Figure 3 is a side view showing the shaft, and Figure 3 is a side view showing the shaft. Figure 4 is a perspective view showing the shaft fitted to the cast rotor;
Fig. 5 is a graph showing the development of chip dimensions, Figs. 6 and 7 show an embodiment of the present invention, and Fig. 6 shows a state in which a cast rotor is fitted into a processing ring. A partially broken side view, and FIG. 7 is a schematic configuration diagram showing a shaft processing device. 01 Cast rotor, 2
'...Shaft, 2a'...Bearing part, 2c'...
Load shaft portion, 2b'...fitting portion, 6...ring. Applicant's representative Patent attorney Takehiko Suzue Figure 1 f゛ 2FT1 Figure 4/1 η・, Figure 3 Figure 5 0 90180270360 □Kakusei

Claims (1)

[Claims] A shaft having a bearing portion and a load shaft portion with a finishing allowance left, and a fitting portion that has been finished is inserted into a cast rotor whose outer diameter has been finished and cast in a punching process, and the shaft is fitted into the cast rotor. After the mating parts are fitted, the cast rotor is pressed into a ring whose inner and outer diameters are machined concentrically, and the bearing part and the load shaft part of the shaft are finished by using the outer diameter of this ring as a reference. A method for manufacturing a rotor, characterized by: