KR102485859B1 - Method for manufacturing rotor of induction motor - Google Patents

Abstract

The present invention relates to a method of manufacturing a rotor of an induction motor, and more particularly, to a method of manufacturing a rotor of a rotor using copper powder to integrally manufacture a rotor bar and an end ring.

Description

Method for manufacturing rotor of induction motor {Method for manufacturing rotor of induction motor}

The present invention relates to a method of manufacturing a rotor of an induction motor, and more particularly, to a method of manufacturing a rotor of a rotor using copper powder to integrally manufacture a rotor bar and an end ring.

An induction motor is a device that receives electrical energy and converts it into rotational kinetic energy. It consists of a stator with a coil wound inside and a magnetic field generated by an alternating current inserted inside the stator and flowing through the stator coil. It consists of a cylindrical rotor that generates an induced current by the rotor, and the rotor is coupled to a cylindrical laminated core provided with a slot, a rotor bar inserted into the slot, and the top and bottom of the cylindrical laminated core, respectively. It consists of an end ring connected to the rotor bar.

In general, in manufacturing a rotor of an induction motor, a method of inserting a rotor bar into a slot of a cylindrical laminated core and welding an annular end ring to the rotor bar is widely used.

However, this method of welding the rotor bar and the end ring is as follows: 1) The material strength of the rotor bar and the end ring is lowered due to high heat during welding, and stress concentration occurs at the welding area, making the joint weak. 2) The fact that the efficiency and performance of the motor deteriorates due to the increase in electrical resistance as the joint area of the weld is reduced or the presence of pores in the weld due to welding gas, 3) Welding the rotor bar and the end ring There are several problems, such as the fact that many processes are required for this.

In order to solve this problem, a method of integrally manufacturing a rotor bar and an end ring through aluminum (Al) die casting has been used, and recently, copper (Cu) having high electrical conductivity has been used instead of aluminum to improve the efficiency of an induction motor. The trend to use it is spreading.

However, the die-casting temperature of copper is very high at about 1300°C compared to the die-casting temperature of aluminum is about 700°C, so expensive die-casting equipment is required to manufacture an induction motor by copper (copper) die-casting, and only copper (copper) die-casting There is a problem that there are very limited places that can be produced domestically/overseas because the manufacturing technology is required.

Korean Patent Publication No. 2013-0122919 (2013.11.11.)

The present invention has been made to solve the above problems, by integrally manufacturing the rotor bar and the end ring of the rotor using copper powder, reducing manufacturing time and manufacturing cost, and simplifying the manufacturing process to increase mass productivity. Its purpose is to provide a method for manufacturing a rotor that can not only expand, but also improve the performance of an induction motor.

A rotor manufacturing method according to an example of the present invention includes a laminated core provided with a slot; a rotor bar inserted into the slot; And, an end ring coupled to both ends of the rotor bar and provided on the upper and lower portions of the laminated core. As a method of manufacturing a rotor of an induction motor comprising a copper powder, the rotor bar and the end ring are integrally manufactured do.

The manufacturing method includes a1) disposing the laminated core in a mold; a2) injecting the copper powder into the mold; a3) compressing the copper powder to form a compact; a4) separating the molded body from the mold; and a5) obtaining a rotor by sintering the molded body.

In step a2), other metal powder may be additionally added in addition to the copper powder.

After step a5), a post-processing step of forging and heat-treating to increase the density of the rotor bar of the rotor may be further included.

The manufacturing method may include b1) disposing the laminated core in a mold; b2) heating and injecting a mixture of the copper powder and a binder into the mold; b3) curing the mixture to form a solid; b4) separating the solid from the mold; and b5) obtaining a rotor by sintering the solid material.

The binder may be formed of a conductive organic material.

After step b4), removing the binder from the solid material may be further included.

The manufacturing method may include c1) placing the laminated core in a mold; c2) injecting the molten aluminum mixed with the copper powder into the mold; c3) hardening the molten aluminum in which the copper powder is mixed to produce a solid material; and c4) taking out the solid material from the mold to obtain a rotor.

The aluminum molten metal in which the copper powder is mixed may be formed by heating a mixture powder in which the copper powder and aluminum powder are mixed, or may be formed by introducing the copper powder into molten aluminum and mixing it.

The manufacturing method may include d1) placing the laminated core in a mold; d2) injecting molten aluminum using a first nozzle and injecting the copper powder into the mold using a second nozzle; d3) hardening the aluminum molten metal mixed with the copper powder to produce a solid; and d4) taking out the solid material from the mold to obtain a rotor.

The first nozzle may be plural, the second nozzle may be plural, or the first nozzle and the second nozzle may be plural.

A rotor according to another example of the present invention includes a laminated core provided with a slot; a rotor bar inserted into the slot; And, end rings coupled to both ends of the rotor bar and provided on the upper and lower portions of the laminated core and integrally formed with the rotor bar, wherein the rotor bar and the end ring are made of a mixture of copper and organic material. is formed with

The rotor, placing the laminated core inside the mold; heating and injecting a mixture of the copper powder and a binder formed of an organic material into the mold; curing the mixture to obtain a solid; separating the solids from the mold; It is prepared by sintering the solid material, and the copper particles and the organic material particles of the binder may be evenly distributed.

A rotor according to another example of the present invention includes a laminated core provided with a slot; a rotor bar inserted into the slot; And, end rings coupled to both ends of the rotor bar and provided on the upper and lower portions of the laminated core and integrally formed with the rotor bar, wherein the rotor bar and the end ring are made of a mixture of copper and aluminum. is formed

the rotor, placing the laminated core in a mold; injecting the molten aluminum mixed with the copper powder into the mold, or injecting the molten aluminum using a first nozzle and injecting the copper powder using a second nozzle; hardening the aluminum molten metal mixed with the copper powder to produce a solid; The solid material may be produced by taking out the mold, and the copper particles and the aluminum particles may be evenly distributed.

The present invention integrally manufactures the rotor bar and the end ring of the rotor using copper powder, thereby reducing manufacturing time and manufacturing cost, simplifying the manufacturing process, increasing mass productivity, and improving the performance of an induction motor. can improve

1 shows a general configuration of an induction motor rotor.
Figure 2 shows each step according to the first embodiment of the present invention in order.
Figure 3 shows each step according to the second embodiment of the present invention in order.
4 shows each step according to the third embodiment of the present invention in order.
5 shows each step according to a fourth embodiment of the present invention in order.

Hereinafter, a method for manufacturing a rotor of an induction motor according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a general configuration of an induction motor rotor, and FIG. 1 (a) shows a laminated core 10, a rotor bar 20, and a Squirrel-Cage combined with an end ring 30 separately, and FIG. 1(b) shows that the laminated core 10 and the Squirrel-Cage are combined.

As shown, the rotor 1 includes a laminated core 10, a rotor bar 20, and an end ring 30, and further includes a shaft 40, which is an essential component of the rotor 1. can

The laminated core 10 is formed in a cylindrical shape by stacking a plurality of unit units having one or more slots, and as the plurality of unit units are stacked, the laminated core 10 has penetrating upper and lower portions of the laminated core 10 in the longitudinal direction. A slot 11 is formed.

The rotor bar 20 is inserted into the slot 11, and for coupling the rotor bar 20 and the end ring 30, the rotor bar 20 is made longer than the length of the laminated core 10, so that the laminated core ( 10) is inserted into the slot 11 so as to protrude from the top and bottom.

The end rings 30 are coupled to both ends of the rotor bar 20, that is, protruding portions from the upper and lower portions of the laminated core 10, and are provided on upper and lower portions of the laminated core 10. Coupling means or coupling structures for coupling the end rings 30 may be provided at upper and lower portions of the laminated core 10 , through which the end rings 30 may be coupled with the laminated core 10 .

The end ring 30 serves to form a circuit by energizing the rotor bars 20, and from the phase difference current alternately applied to the stator (not shown), a circuit composed of the rotor bar 20 and the end ring 30 An induced current flows, and an induced electromotive force is generated due to the interaction of the magnetic field generated by the phase difference current and the induced current flowing in the rotor bar, so that the rotor rotates.

On the other hand, as described above, conventionally, in order to manufacture such a rotor, a separately manufactured conductor rotor bar 20 is inserted into the slot 11 of the laminated core 10, and both ends of the rotor bar 20 are inserted. Although the method of welding the end ring 30 or the aluminum or copper die-casting method was used, the welding joint method requires many processes, the aluminum die-casting method has poor conductivity, and the copper die-casting method is difficult to manufacture. Each has its own problems, such as being expensive.

The present invention has been made to solve the problems in each of these conventional methods, and by integrally manufacturing a rotor bar and an end ring using copper powder, it is possible to simplify the rotor manufacturing process and the like, and at the same time achieve high conductivity of copper. As a result, the performance of the induction motor can be improved.

Hereinafter, an embodiment of a rotor manufacturing method in which a rotor bar and an end ring are integrally manufactured using copper powder will be described.

Example 1: Powder metallurgy method

In general, powder metallurgy refers to a technology for producing a metal product by compacting metal powder or alloy powder and then sintering the powder at a melting temperature or lower.

As shown in FIG. 2 , according to the present invention, a rotor may be manufactured using a powder metallurgy method using copper powder. To this end, the present invention may include the following steps.

a1) arranging the laminated core inside the mold;

a2) injecting copper powder into the mold;

a3) forming a molded body by compression molding the copper powder;

a4) separating the molded body from the mold;

a5) obtaining a rotor by sintering the compact;

A more detailed description of each step is as follows.

First, the laminated core is placed inside the mold. The mold may be formed by combining a plurality of partial molds so that the laminated core is disposed therein.

After placing the laminated core inside the mold, copper powder is injected into the mold through an injection port communicating with the inside of the mold. Through this, copper powder is filled in the positions where the slots and end rings of the laminated core are to be formed.

After the copper powder is filled in the mold, the molded body corresponding to the primary solid material is formed by compression molding the copper powder. Specifically, when the injection port of the mold is closed and heat and/or pressure is applied through a press or the like to compress the copper powder, the powder is hardened to form a compact.

After the molded body is formed, the molded body is separated from the mold. For example, when the mold is formed by combining a plurality of partial molds as described above, the molded body may be separated from the mold by removing each of the plurality of partial molds from the mold.

After separating the molded body from the mold, the molded body is sintered, that is, heated at a temperature below about 1084 ° C., which is the melting point of copper, to bond or solidify the copper, thereby obtaining a rotor equipped with a rotor bar and an end ring in a laminated core. there is. However, the shaft may not yet be inserted and bound to the rotor, and in this case, a step of inserting and binding the shaft to the rotor obtained through the present invention may be further included. The same applies to other embodiments below.

Since the rotor bar and the end ring are formed of copper, the rotor of the present invention obtained through this has excellent conductivity compared to aluminum, so that the performance of the motor can be improved.

In addition, since the manufacturing process is simple compared to the conventional fusion bonding method, mass productivity can be expanded, and the structure can be formed more uniformly than the die casting method.

However, there may be a problem in that the mechanical properties, that is, the density of the rotor bar, is lowered in terms of physical properties compared to the conductor rotor bar used in the fusion bonding method and the die casting method. In order to compensate for this, the present invention can form the rotor bar and the end ring with the powder mixture by additionally introducing other types of metal powder in addition to the main material copper powder. Other types of metal may be iron, nickel or aluminum, for example.

Furthermore, after sintering the molded body, a post-treatment process such as forging and heat treatment may be further included to further improve mechanical properties, particularly crystal density, of the rotor bar.

On the other hand, in this embodiment, the method of manufacturing the rotor by first placing the manufactured laminated core inside the mold has been described, but in a different order, the primary conductor in which the endring and the rotor bar are integrated through the first mold ( squirrel-cage), and then place the primary conductor inside the second mold through the second mold to obtain a secondary conductor in which the primary conductor and the laminated core are integrated, that is, the rotor. At this time, the metal and/or manufacturing method used for manufacturing the primary conductor and the metal and/or manufacturing method used for manufacturing the secondary conductor may be different from each other, such a difference in order, difference in metal and/or manufacturing method may be equally applied in all embodiments below.

Example 2: Powder injection molding method

In general, powder injection molding (powder injection molding) is a mixture of metal or ceramic powder and a binder made of an organic material, molding using an injection molding method, removing the binder, and finally sintering to metal products or ceramics. It refers to the technology that makes a product.

As shown in FIG. 3 , according to the present invention, a rotor may be manufactured using a powder injection molding method using copper powder. To this end, the present invention may include the following steps.

b1) arranging the laminated core inside the mold;

b2) heating and injecting a mixture of copper powder and a binder into the mold;

b3) curing the mixture to form a solid;

b4) separating the solid from the mold;

b5) sintering the solid to obtain a rotor;

A more detailed description of each step is as follows.

First, the laminated core is placed inside the mold. Contents overlapping with those described in Example 1 above will be omitted below.

After placing the laminated core in the mold, a mixture of copper powder and binder is heated and injected. At this time, the mixture is heated so that the copper powder is sufficiently kneaded. The binder may be formed of an organic material, and is heated to perform a function of adhering the copper powder.

After the mixture is injected into the mold, the mixture is cured to form a solid material. Here, the mixture may be cooled and solidified to harden.

After the mixture is cured to form a solid, the solid is separated from the mold, and the solid separated from the mold is sintered to obtain a rotor.

In the rotor of the present invention obtained through this, the rotor bar and the end ring are formed of a material mixed with copper and organic material, the copper particles and the organic material particles of the binder are evenly distributed, and since this material contains copper, the conductivity is aluminum. It is very superior compared to , so the performance of the motor can be improved.

In addition, metal powder injection molding has a simple and simple manufacturing process, and manufacturing costs can be reduced. Furthermore, when the sintering temperature is raised and proceeded sufficiently, a high-density sintered body can be made, and the conductivity of the rotor bar can be further improved. Here, when the binder is formed of a conductive organic material, the binder itself becomes conductive without the step of removing the binder, as will be described later, so the conductivity of the rotor bar can be further improved, and the binder removal step is omitted, thereby omitting the entire manufacturing process. can be further simplified.

On the other hand, the present invention may further include a degreasing step of removing the binder before sintering after separating the solids, and may remove the binder through a degreasing method such as solvent degreasing, hot degreasing, or catalyst degreasing. By removing it, the conductivity of the rotor bar can be further increased, and the cost can be reduced by using the above-described conductive organic material.

Example 3: aluminum die casting method mixed with copper powder

In general, die casting is a precision casting technique in which a casting identical to that of the mold is obtained by injecting molten metal into a mold accurately machined to completely match the casting shape. The casting, that is, the product obtained by using die casting is called a die casting casting.

As shown in FIG. 4 , in the present invention, a die-cast rotor can be manufactured through an aluminum die-casting method using copper powder. To this end, the present invention may include the following steps.

c1) placing the laminated core in a mold;

c2) injecting molten aluminum mixed with copper powder into the mold;

c3) hardening the molten aluminum in which the copper powder is mixed to produce a solid material;

c4) taking out the molded body from the mold to obtain a rotor;

A more detailed description of each step is as follows.

First, the laminated core is placed inside the mold. As described above, the mold is machined and precisely formed to cast the rotor bar and the end ring.

After the mixture is injected into the mold, the aluminum molten metal mixed with the copper powder is injected. Here, the aluminum molten metal in which copper powder is mixed means a molten metal formed by heating a mixed powder of copper powder and aluminum powder or by adding copper powder to molten aluminum and mixing it.

Specifically, when the mixed powder of copper powder and aluminum powder is heated to a temperature equal to or higher than the melting point of aluminum, aluminum is melted to form a molten metal, and copper is hardly melted and can be mixed into the aluminum molten metal in a powder state. Manufacturing the molten metal in this way can spread the copper powder relatively uniformly in the molten metal and allow the aluminum to be easily melted.

Alternatively, aluminum molten metal may be first made by melting aluminum in a powder or in any form other than powder, and copper powder may be added to the aluminum molten metal and mixed to form an aluminum molten metal in which copper powder is mixed. Manufacturing of molten metal in this way can reduce the cost of producing molten aluminum.

After injecting the aluminum molten metal mixed with copper powder into the mold through an injection port, etc., the molten metal inside the mold is hardened to produce a solid material, and the resulting solid material is taken out of the mold to form a rotor bar and an end ring on the laminated core. A rotor equipped with this can be obtained. Thereafter, a post-processing step such as finishing may be further included.

The rotor of the present invention obtained through this is formed of a mixed material of copper and aluminum, the copper particles and the aluminum particles are evenly distributed, and since copper is included in the rotor bar and the end ring, it is more conductive than conventional aluminum die-casting. This can be greatly increased.

In addition, since the price is low and the production speed is fast, mass production is possible, the process is simplified, and the conductivity can be improved because the density of the rotor bar is high.

Example 4: copper powder, aluminum hybrid die casting method

In the above-described aluminum die casting method, instead of using the aluminum molten metal mixed with the copper powder, the rotor may be manufactured by separately introducing or injecting the copper powder and the aluminum molten metal into the mold.

That is, as shown in FIG. 5, the present invention includes injecting molten aluminum into the mold using the first nozzle and injecting copper powder using the second nozzle, instead of step c2) described above. It can be done by

That is, two nozzles communicating with the inside of the mold may be formed independently, and one nozzle may inject only molten aluminum into the mold, and the other nozzle may inject copper powder into the mold.

According to this, it is possible to omit the process of mixing the copper powder with the aluminum molten metal, and thus the rotor manufacturing process can be further simplified. However, as described above, when two nozzles are formed, there may be a problem in that the copper powder is not mixed relatively uniformly with the aluminum molten metal. In order to solve this problem, a plurality of first nozzles for injecting molten aluminum and/or second nozzles for injecting copper powder may be formed to be dispersed to each other so that the copper powder is evenly distributed in the molten aluminum.

Although the above has been described with reference to the preferred embodiments of the present invention, the present invention is not limited thereto, and the technical idea of the present invention and the claims to be described below by those skilled in the art to which the present invention belongs Of course, various modifications and variations are possible within the equivalent range of.

1: rotor
10: laminated core
11 : slot
20: rotor bar
30: end ring

Claims (15)

a laminated core provided with a slot; a rotor bar inserted into the slot; And, as a rotor manufacturing method of an induction motor comprising; end rings coupled to both ends of the rotor bar and provided on the upper and lower portions of the laminated core,
By integrally manufacturing the rotor bar and the end ring using copper powder,
a1) arranging the laminated core in a mold;
a2) injecting the copper powder into the mold;
a3) compressing the copper powder to form a compact;
a4) separating the molded body from the mold; and,
a5) obtaining a rotor by sintering the molded body;
After the step a5), post-processing to increase the density of the rotor bar of the rotor; further comprising a rotor manufacturing method.
delete According to claim 1,
In step a2),
A method for manufacturing a rotor, characterized in that additionally adding other metal powder in addition to the copper powder.
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