JPS5956854A - Manufacture of rotor for squirrel-cage induction motor - Google Patents

Abstract

PURPOSE:To reduce the manufacturing cost of an induction motor by forming a vent gap forming piece formed with an insert of the same material as a conductor between conductor casting space of water soluble casting material, thereby enabling to work at an ambient temperature for a short period. CONSTITUTION:A vent gap forming piece 1 is molded to form conductor casting spaces 2 corresponding to slots formed at a core in a circumferential direction with water soluble casting mixture sand. The spaces 2 of the piece 1 are disposed with foamable styrol mold 4 internally mounted in a tube 3 of the same material as the aluminum conductor of the shape corrsponding to the conductor casting space at the molding time, after molding, the mold 4 is burnt out in the drying step. In this manner, the molding can be performed at the ambient temperature for a short period, thereby manufacturing inexpensively the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a rotor for a squirrel-cage induction motor, which is made by casting aluminum conductors, for example.

[Technical background of the invention and one issue] When manufacturing rotors for squirrel-cage induction motors, the die-canut method or low-pressure casting method is used to tighten laminated silicon steel plates, and then molten metal such as aluminum is poured into the silicon steel plates. A technical means is known in which conductors, short-circuit rings, and cooling vanes are injected into holes formed by punched holes and integrally cast, but the rotor installed in a large-capacity induction motor is In order to increase cooling efficiency, only a conductor is connected between the blocks of multiple laminated silicon steel plates, and a space is provided where the silicon steel plates are not stacked, and this space acts as a ventilation duct.

The ventilation duct forming method for induction motors involves joining or mechanically attaching a tubular spacer piece (of the same type as the silicon steel plate or the same type as the conductor) to the silicon steel plate iron core by welding or mechanically matching the shape of the silicon steel plate nullot. Metal molds divided into parts are laminated when laminating silicon steel plates, and the metal molds are removed after casting the molten metal and solidifying. When laminating silicon steel plates and setting them in the mold for casting.

A steel bar was inserted into the core slot from the mold, and after injecting molten metal, the steel bar was removed, and a tubular secondary conductor was inserted into the short circuit ring of the capacity via the short circuit ring and the system slot to form a ventilation hole. In this case, the molded piece of the duct part is made of a low-melting point metal, and after the molten metal is injected, it is heated to near the melting point of the low-melting point metal, and the low-melting point metal is removed using centrifugal force.

However, the above ventilation duct forming methods all have operational difficulties and are not practical. In other words, joining the silicon steel plate and the spacing piece requires a special welding machine, positioning jig, and tubular spacing piece forming equipment necessary for joining, and the method using a metal mold requires the cost of processing the metal mold and mold removal equipment. In the method of inserting a secondary conductor and injecting molten metal, if the bond between the molten metal and the secondary conductor is poor, the cooling efficiency decreases and it is also troublesome to fix the secondary conductor.

Furthermore, in the method of making the duct part molded piece using a low melting point metal, the melting point of this low melting point metal is lower than the melting point of molten aluminum, so the low melting point metal is melted into the molten aluminum, and the duct part molded piece after the aluminum solidifies. Removal of metal requires heating near the melting point of the low melting point metal, resulting in high temperature work and poor working environment.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and the continuous kite single-gap molded piece is formed from a water-soluble mold material, so that the work can be performed at room temperature in a short time, and the product can be manufactured at a low cost. It is an object of the present invention to provide a method for manufacturing a rotor for a squirrel-cage inductive four-motor.

[Summary of the invention]

An object of the present invention is to form a ventilation gap molded piece in which a tubular or cylindrical intervening body made of the same material as the conductor is provided in a conductor casting space using a water-soluble mold material, and to place this ventilation gap molded piece between an iron core. A conductor in the form of a bath melt is injected into the conductor casting space of the core laminate, the molten conductor is cast and fused, and the ventilation gap molded piece is melted and removed with water. Communication
This is achieved by a method of manufacturing a rotor for a squirrel-cage induction motor in which a lice duct is formed.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a ventilation gap molded piece 1 used for carrying out the method of the invention, and this ventilation gap molded piece 1 is a water-soluble @
It is molded using mixed molding sand so as to form conductor casting spaces 2 corresponding to slots provided in the core in the circumferential direction. The ventilation gap molded piece l has the same outer diameter as the iron core, and its thickness is set according to the dimensions of the ventilation duct. The conductor casting space 2 of the ventilation gap molded piece 1 is formed by placing a styrofoam model 4 inside a tubular body 3 made of the same material as the aluminum conductor and having a shape corresponding to the conductor casting space. It is produced by burning out the foamed nutirol model 4 in the drying process. The tubular body 3 has a stronger affinity for the water-soluble salt contained in the water-soluble @-mold mixed sand than the @-mold material used in general molding, so this tubular body 3 is suitable for wj-type drying. Sometimes, the conductor casting space 2 is integrally connected to the molded piece 1, and a complex-shaped conductor casting space 2 is formed by providing a foamed nutirol model 4 in the conductor casting space 2.
formation becomes possible.

On the other hand, a predetermined number of silicon steel plate iron cores 5, which are formed by punching out outer diameters, slots, inner holes, etc., are stacked together using a jig, and in this stacked body 6, the ventilation gap piece l, the conductor casting space 2, and the slot 7 are aligned. After being alternately laminated to form an iron core laminate, it is inserted into a temporary shaft 8 for forging as shown in FIG. This assembly is placed in a conventional mold 9 and sufficiently tightened by a pressure device (not shown). In the mold 9,
A blade forming space 10 and a short-circuit ring forming space 11 are formed, and bath-molten aluminum is injected into these spaces 10.1. The short-circuit ring forming space 11 is connected to the conductor casting space 2 via the slot 7.

When molten aluminum is injected into the vane forming space 10 and the short-circuit ring forming space 11 of the mold 9, the molten aluminum passes through the slot 7 and reaches the υ conductor casting space 2. The inner surface of the body 3 is melted, and the tubular body 3 is fused with the molten aluminum to become one body.

The tubular body 3 of the ventilation gap molded piece 1 also acts as a kind of cooling metal, and the cooling rate is the same as that of the molten aluminum in the core core, and the cooling proceeds from the tubular body 3 side to the center of the aluminum conductor. Accompanying coagulation will occur. Furthermore, the solidification of molten aluminum within the core Nulot of the iron core becomes smooth, and therefore molten metal can be smoothly replenished from the hot water supply port or riser.

Once the molten aluminum has solidified, the casting rotor is immersed in water or hot water. As a result, the soluble salts contained in the mold material of the ventilation gap molded piece 1 are melted in water, and the mold loses its binding force and easily collapses, causing no mechanical force to be applied. removed from A. This forms a casting rotor 1/'C')1r3 wind duct. If this work is done while the rotor is still hot after casting, the caster rotor will easily dry out due to the amount of heat added during the casting process after removing the ventilation gap molded piece l, and the rotor will easily dry out when the rotor is hot. This also has the effect of preventing rust on the surface of the iron core.

It goes without saying that the above operation can be carried out without any problem even after the casting rotor has cooled down.

Then, by cutting out the sprue etc., a cast rotor will be made.

4 to 7 show embodiments of the pond of the present invention. In the embodiments shown in FIGS. 4 and 5,
By placing an aluminum pipe 20 in the middle of the conductor casting space 2 of the ventilation gap molded piece 1, tightening the aluminum pipe 20 with water pressure or a hydraulic machine, and casting the molten aluminum in this state, The aluminum pipe 20 will be cast. In this case, the outer diameter of the aluminum pipe 20 is set to be smaller than the width of the conductor casting space 2, wider than the conductor casting space 21 in the core, and large enough to be sufficiently surrounded by the molten metal when molten aluminum is cast. ing.

In addition, in the central Mli example shown in FIGS. 6 and 7,
An aluminum block 30 is placed in the conductor casting space 2 and cast in the same manner as in the embodiments of FIGS. 5 and 6. The aluminum block 30 is also set under the same conditions as the aluminum block 20.

〔Effect of the invention〕

As described above, according to the present invention, a ventilation gap molded piece is made using a water-soluble mold material, and a tubular or cylindrical interposition made of the same material as the conductor to be cast is placed in the conductor casting space of the ventilation gap molded piece. Since this intervening body is fused with the molten conductor, the cooling rate of the conductor cast in the conductor casting space in the core and the conductor casting space in the ventilation gap molded piece can be made uniform. Therefore, since the intervening body acts as a resistor against the clamping load, the molded pieces in the ventilation gap between the iron cores will be destroyed by the clamping load iK. Without a doubt.

Moreover, since the molded piece of the ventilation gap can be removed in a short time at room temperature, the working environment can be improved.

[Brief explanation of drawings]

Fig. 1 is a partial plan view of a ventilated gap molded piece used to carry out the method of the present invention, Fig. 2 is a sectional view of the ventilated gap molded piece, and Fig. 3 is an explanation showing the step of casting a conductor. Figure, 4th
The figure is a partial plan view showing an example of the function of the ventilation gap molded piece, FIG. 5 is a cross-sectional view of the same, FIG. It is the same sectional view. 1... Ventilation gap molded piece, 2... Conductor casting space, 3...
...Tubular body, 4...Model, 5...Iron core, 9...Mold, ]0...Blade forming space, 11...Short ring forming space. Applicant's agent: Inomata

Claims (1)

[Claims] A ventilation gap molded piece is formed using a water-soluble mold material with a tubular and cylindrical intervening body made of the same material as the conductor to be cast in the conductor casting space, and this ventilation gap molded piece is placed between the iron cores. to form an iron core laminate, inject molten conductor metal into the conductor casting space of this core laminate, cast and fuse the molten conductor metal, and then dissolve and remove the ventilation gap molded pieces using water. A method of manufacturing a rotor for a squirrel-cage induction motor, characterized in that a ventilation duct is formed using a rotor.