JPS6048986B2 - Manufacturing method of induction motor rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an induction motor rotor, and particularly to a method for joining electrical conductors thereof.

As shown in a perspective view in FIG. 1, the rotor of an induction motor includes an iron core 1 stacked in the axial direction, a plurality of bars 2 embedded in the outer circumference of the iron core 1 so as to extend in the axial direction, and bars 1. The bar 2 and the end rings 3 are conventionally made of copper or an alloy thereof, and are assembled by brazing. It has been joined.

On the other hand, in recent years, there has been a trend to change the material of the bar 2 and end ring 3 to aluminum or its alloy in order to make electric motors smaller and lighter and to reduce costs. In that case, brazing aluminum currently lacks reliability, and even if the quality of brazing is improved, it takes time and effort to remove the residue of the highly corrosive flux used to remove the oxide film on the aluminum surface, making it difficult to achieve a high level of reliability. This method has the disadvantage that it is unsuitable for joining rotating objects such as electric motors that require high performance. Therefore, when using aluminum material for the induction motor rotor conductor, as shown in Fig. 2, radial slits 4 are machined in the end ring 3 of the thick plate, and the tip of the bar 2 is inserted into the slit 4. After that, a deep U-shaped welding groove 5 is cut into the end ring 3 and the insertion part of the tip of the bar 2 into the slit 4, and welding is performed by metal inert gas arc welding (MIG welding). This method has been adopted as a joining method in place of brazing.

However, with this method, a large amount of man-hours and time are required for the slit machining or groove machining of the end ring 3, which is inevitably discontinuous machining, and furthermore, since the MIG welding method is used, the amount of heat input is inevitably excessive. This means that the welded shape is large, and even though age-hardening aluminum alloy, which has high strength and relatively good electrical conductivity, is used as the material for the bar 2, the material properties of the material deteriorate due to excessive heat input. However, the transition to aluminum as an electrical conductor has not been easily realized. Furthermore, in order to eliminate this drawback, the ends of the end ring 3 and the bar 2 are butted against each other in a T-shape as shown in the perspective view in FIG. It is believed that efficiency can be significantly improved if the welding is performed using electron beam welding, which allows for deep penetration. However, in that case, the same cross section cannot be obtained all around the joint, so the T-joint corner 6 in Fig. 3 may be melted down by the electron beam, and if you try to prevent this, the T-joint corner 6 in Fig. 3 may be melted down over the entire joint surface. This method is not suitable for joining rotor conductors, which requires high reliability in terms of fatigue strength, as it becomes difficult to join the joints and unwelded parts 7 remain at the joints near the corners of the T-joints. It was hot. Note that 8 in FIG. 3 indicates electron beam welding heat. This invention was made in order to eliminate the drawbacks of the conventional method as described above, and in joining a bar and an end ring, both ends of a plurality of pars arranged at equal intervals on one circumference are used. Insert an end ring along the inner circumference of the section, and insert a thin disc with radial protrusions on the outer circumference so that the protrusions are at the ends. Cover the end ring so that it is inserted between the bars on the ring, and then continuously join the parts where the bar and the end ring contact by electron beam welding or laser welding to bond the bar and the end ring. High efficiency and reliability are achieved by integrating the The purpose of the present invention is to provide a method for manufacturing an induction motor rotor with high efficiency.

An embodiment of the present invention will be described below with reference to the drawings. Fourth
The figure is a plan view showing a thin disk 9 used in the method of the present invention, in which the bar 2 and the end ring 3 are made from a thin plate made of the same kind of material by punching or high-efficiency cutting such as plasma cutting, so that the outer periphery is spaced apart. A gear-shaped protrusion 11 is machined to have a radial slit 10. In this case, the depth of the slit 10, that is, the height H of the protrusion 11 is the thickness of the end ring, the width W1 of the bottom of the slit 10 is the width of the bar 2, and the width W2 of the protrusion 11 is the distance between the bars 2. and each shall be processed equally. This slitting process uses thin plates, so punching or plus cutting,
High-efficiency and high-precision processing methods such as laser cutting can be applied, and the manufacturing time is dramatically reduced compared to the conventional method of slitting shown in FIG. FIG. 5a is a partial perspective view showing the main parts of one embodiment of the present invention, and FIG. 5b is a
It is a sectional view at a B-■ type fountain. As shown in FIG. 5, the thin disk 9 produced as described in connection with FIG. If the bar 2 and the end ring 3 are brought into close contact with each other by electron beam welding, and then the circumference of the contact between the bar 2 and the end ring 3 is continuously welded by electron beam welding, as shown by P in the partially enlarged cross-sectional view of FIG. Because the thin disc 9 exists in the gap between them, the T-joint corner shown in Fig.
Burn-through does not occur in a portion, and it becomes possible to join and integrate the bar 2 and the end ring 3 by continuous single-layer welding. As described above, according to the method of the present invention, thin-walled circles are efficiently provided with gear-shaped protrusions by punching or cutting between the bars that serve as electrical conductors of the induction motor rotor and on the outer main surface of the end ring. Because the plates are brought into close contact with each other, there are no discontinuities in the joint, making it possible to apply electron beam welding, which can produce high-quality joints with high efficiency.This dramatically improves the joining efficiency of induction motor rotor conductors, and at the same time This has the effect of improving quality and making it possible to change the conductor material from copper to aluminum.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the conventional structure of an induction motor rotor, which is the object of the present invention, and FIG. 2 shows a conventional joining method for using aluminum as a rotor conductor. a is its front view, and Figure 2 b is ■B in Figure 2 a.
-■ It is a sectional view taken along line B. FIG. 3 is a perspective view showing the drawbacks when electron beam welding is applied without using a thin disk, FIG. 4 is a front view showing a thin disk used in the present invention, and FIG. A perspective view showing the main parts of the embodiment, FIG. 5b is a perspective view of FIG. 5a (7) VB-Vf
The sectional view at the spring, FIG. 5C, is a partially enlarged view. In the figure, 2 is a bar, 3 is an end ring, 9 is a thin metal plate, and P is a welded part.

Claims (1)

[Claims] 1. The ends of a plurality of bars that are arranged at equal intervals on the outer circumference of the induction motor rotor and that each extend in the axial direction and are to serve as electrical conductors are arranged at the above-mentioned predetermined intervals on the peripheral end surface of an end ring made of a metal material. At the same time, after disposing a thin plate made of a metal material and continuously covering from the outer main surface of the end ring to the circumferential end surface between the bars, The part where the end ring contacts the end ring is directly connected to the joining surface, and the part between the bars is made by continuously welding the thin plate and the end ring from above the thin plate by electron beam welding or laser welding. A method of manufacturing an induction motor rotor, comprising a step of welding and joining and integrating the bar and the end ring.