JPH044737A - Manufacture of squirrel cage electric rotating machine - Google Patents

Abstract

PURPOSE:To joint a rotor bar rigidly to a short-circuit ring by thermally brazing the rotor bar and the short-circuit ring while bringing them into pressure contact by means of a ring for pressing a plurality of rotor bars by means of a plurality of inwardly projecting pressing sections. CONSTITUTION:An annular soft steel ring 4 is applied on the tip of a stator bar 1 projecting annularly from the outer circumferential end of a rotor core 3 prior to brazing. Female holes are made in the ring 4 with same pitch as the rotor bar 1 and a push screw 9 is screwed therein with the inside end thereof contacting with the rotor bar 1. When a short-circuit ring 2 is heated by a brazing burner 8 to expand and provide a gap between the tip of the rotor bar 1 and the short-circuit ring 2, a push screw 9 is driven by means of a ratchet wrench to press the rotor bar 1 against the short-circuit ring 2 with a proper force. Since silver filler spreads over the entire contact area through capillary, the rotor bar 1 and the short-circuit ring 2 are brought into tight contact when the push screw 9 is tightened again after heating with the burner 8.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a method of manufacturing a squirrel cage rotating electric machine.

(Prior Art) In FIG. 2 showing a conventional manufacturing method of a squirrel-cage rotating electric machine and FIG. 3 showing a perspective view thereof, there is a shaft end side of the rotor core 3 inserted into the rotor strip 7. Spacer pieces 5 are provided at predetermined intervals, and an annular presser plate 6 is inserted into the shaft end side of the outer spacer piece 5, and a key 6a embedded in the outer periphery of the shaft 7 at the outer end is inserted. Fixed.

On the other hand, from each slot 3a formed in the axial direction on the outer periphery of the rotor core 3, rotor bars 1 respectively protrude in the axial end direction of the rotor shaft 7, and the inner surfaces of these rotor bars 1 The outer circumferential surface of a shorting ring 2, which has a square cross section in FIG. 2 and an annular shape when viewed from the right side in FIG.

That is, in the squirrel cage rotating electrical machine configured in this way, when brazing the shorting ring 2 to the inner surface of the rotor bar 1, the shorting ring 2 is inserted into the inner circumference of the rotor bar 1, and then the rotor bar 1 is and short-circuit ring 2 are heated with a brazing burner 8 (or high-frequency heating), and the silver solder supplied to the joint surface of rotor bar 1 and short-circuit ring 2 is melted and poured into the joint surface.

However, in such a brazing method, the heated short-circuit ring 2 expands due to heat, and the rotor bar 1 is pushed up in the outer circumferential direction and bent by one curve. Then, rotor bar 1 and short circuit ring 2
A gap is created at the joint surface of the rotor bar 1, and the gap becomes wide especially on the shaft end side, which not only prevents the molten silver solder from penetrating through capillary action, but also causes it to flow away. Hit the rotor bar 1 with a hammer to reduce the gap, and when the silver solder is melted, quickly remove the rotor bar 1 with a hand knife.
and clamps the shorting ring 2.

(Problem to be solved by the invention) However, with this brazing method, since the correction with a hammer is done manually, not only does the gap after correction vary, but also if the timing of tightening the hand blade is too early. If the penetration of the silver solder is insufficient and the tightening is delayed, the silver solder may flow out from the wide gap.

Furthermore, even if the knife blade is initially tightened with an appropriate tightening force, it may loosen due to the heat transfer between the heated rotor bar 1 and the short circuit ring 2, causing the gap to increase.

And if as a result, the end of the rotor bar 1 and the short circuit ring 2
If the bonding force at the joint is weak, the adjacent rotor bars 1 will be heated to approximately the same temperature when brazing, so there is a possibility that a small gap may be formed at the tip.

Then, due to the heat cycle caused by the start and stop of the squirrel-cage rotating electric machine and stress concentration in the gap due to centrifugal force during operation, minute peeling may occur from the gap, and there is a risk that it will further develop over a long period of operation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a squirrel-cage rotating electrical machine that can firmly join a rotor bar to a short-circuit ring.

[Structure of the invention]

(Means and effects for solving problem il1) The present invention provides a method for manufacturing a squirrel-cage rotating electric machine in which a rotor bar and a short-circuit ring of the squirrel-cage rotating electric machine are joined, in which a pressing tool is fixed to the outer periphery of the rotor bar. , by pressing the rotor bar with the plurality of pressing parts inside this pressing tool, heating the rotor bar and the short-circuit ring, and brazing the rotor bar to the short-circuit ring, the rotor bar is connected to the short-circuit ring. This is a method for manufacturing a squirrel cage rotating electrical machine that can be firmly brazed.

(Example) An example of the method for manufacturing a squirrel cage rotating electric machine according to the present invention will be described below with reference to the drawings. However, parts that overlap with Figures 2 and 3 are omitted.

In FIG. 1, the outer circumference of the tip of the stator bar 1 which protrudes annularly from the outer circumferential end of the rotor core 3 has an inner diameter of the stator bar 1.
An annular ring 4 made of mild steel that is approximately 10++e larger than the annular outer circumference of is inserted into the wax neck, and this ring 4 has female threaded holes formed at equal pitch intervals with the rotor bar 1. A headless push screw 9 with a nominal length approximately equal to the radial thickness of the ring 4 is inserted into the screw hole so that the inner end is connected to the rotor bar 1.
It is screwed into contact with the

Next, a method of brazing the stator bar 1 and the short-circuit ring 2 of the squirrel-cage rotating electric machine configured as described above will be explained.

As in the past, when the short circuit ring 2 heated by the brazing burner 8 expands and a gap is created between the tip of the rotor bar 1 and the short circuit ring 2, the push screw 9 is turned with a ratchet wrench.
The rotor bar 1 is pressed against the shorting ring 2 with an appropriate force. Then, the silver solder permeates over the entire contact surface due to capillary action, so by retightening the push screw 9 during cooling after the heating by the burner 8 is stopped, the two are brought into close contact.

At this time, the tip of the rotor bar 1 should be recessed by about 3 inches from the right side surface of the shorting ring 2, as shown in the figure. As a result, an arc-shaped adhesive part is formed by the adhesion force of the silver solder at the corner formed by the tip end surface of the short-circuiting ring 2 and the outer circumferential surface of the short-circuiting ring 2, resulting in a strong joint without peeling from the stress concentration area. Becomes a department.

Furthermore, when brazing adjacent rotor bars 1, the procedure is similar to that described above, but at this time, the adjacent brazing parts that were brazed first are pressed by the push screws 9. , there is no risk of peeling of the tip.

Thereafter, when brazing the next adjacent rotor bar 1 in the same manner as described above, the silver solder will not flow out when the rotor bar 1 and the short-circuit ring 2 are brazed, and the Since no manual work is required, it is possible to obtain a method for manufacturing a squirrel-cage rotating electrical machine that can be firmly joined without requiring operator skill, regardless of the thermal expansion of the short-circuit ring 2.

In the above embodiment, the ring 4 with a push screw that presses the rotor bar 1 against the short-circuit ring 2 is annular. Alternatively, it may be shorter, for example, in the shape of a 1/4 arc.

At this time, when attaching and fixing the arcuate ring to the outer periphery of the rotor bar 1, use a slightly large knife to make the overlapping portions of the rotor bar 1 and the short-circuit ring collinear from the outside. Also, it is preferable to braze not on the clamp part but on the adjacent inner part.

〔Effect of the invention〕

As described above, according to the method for manufacturing a squirrel-cage rotating electric machine of the present invention, the rotor bars are pressed against the short-circuit ring using the press ring that presses the rotor bars with the plurality of press parts protruding inward. Since the short-circuit ring is heated and the rotor bar is brazed to the short-circuit ring, it is possible to obtain a method for manufacturing a squirrel-cage rotating electric machine in which the rotor bar can be firmly joined to the short-circuit ring.

[Brief explanation of drawings]

Fig. 1 is a partial perspective view showing a method for manufacturing a squirrel-cage rotating electric machine according to the present invention, Fig. 2 is a partial vertical sectional view showing a method for manufacturing a conventional squirrel-cage rotating electric machine, and Fig. 3 is a conventional squirrel-cage rotating electric machine. FIG. 2 is a partial perspective view showing a manufacturing method. 1...Rotor bar 2...Short ring 4...Ring 8...Burner 9...Press screw Agent Patent attorney Yoshiaki Inomata (and 1 other person) Figure 1 Figure 3

Claims (1)

[Claims] A method for manufacturing a squirrel-cage rotating electric machine in which a rotor bar and a short-circuit ring of the squirrel-cage rotating electric machine are joined together, wherein a pressing tool presses a plurality of rotor bars to the short-circuit ring using a pressing portion on the inner circumference of the rotor bar. is fixed, and the pressing part of this fixture presses the rotor bar against the short circuit ring, heats the rotor bar and the short circuit ring, and brazes the rotor bar to the short circuit ring. Electrical manufacturing method.