KR20230072597A - Method for manufacturing rotor for an electric motor using a simple mold using gravity casting - Google Patents

Abstract

A method for manufacturing a rotor for an electric motor using a gravity casting method according to the present invention includes forming a rotor core by laminating a plurality of punched circular steel plates; coupling a plurality of conductor bars on the inside of a plurality of slots formed inside an outer circumferential surface of the rotor core; arranging the rotor core coupled with the plurality of conductor bars in a simple mold separated from the top and bottom; forming end rings on both sides of the rotor core by a gravity casting method by supplying aluminum through the simple mold; and separating the simple mold to obtain a completed rotor core.

Description

Method for manufacturing rotor for an electric motor using a simple mold using gravity casting method {Method for manufacturing rotor for an electric motor using a simple mold using gravity casting}

The present invention is a method to form the end ring part by gravity casting method by supplying aluminum melt in a state where a rotor core assembled with a conductor bar is placed in a simple mold made of two upper and lower stages instead of the conventional die casting process. it's about

Conventionally, a conductor in a rotor constituting a three-phase induction motor or generator is manufactured by injecting aluminum or copper molten metal using a vertical or horizontal die-casting machine.

The motor includes a stator fixedly installed in a motor housing or frame, and a rotor positioned rotatably inside the stator. The rotor includes a rotor core formed in the center of a plurality of punched circular steel plates, a plurality of conductor bars coupled to the inside of a plurality of slots radially formed adjacent to the inner circumferential surface of the circular steel plate with the rotor core as the center, and the conductor bars It is configured to include end rings integrally coupled at both ends of the.

Conventionally, in the rotor manufacturing process constituting an induction motor, an aluminum or copper ingot is melted into molten metal, and then the rotor core is inserted into a mold made of die casting equipment, and then the aluminum or copper molten metal is injected by a vertical or horizontal die casting machine After fabrication, it is produced through post-processing process.

Existing processes for manufacturing rotors require the use of expensive die-casting equipment as described above, and there is a limit in that die-casting equipment is not suitable for small-volume production. During die casting, in order to set the casting conditions, test die casting must be carried out at least once or twice, so at least 20 to 30 rotor rotors must be consumed. There is a limit to this. In addition, there is a practical limitation that post-processing is essential since the thickness of the rib must be maintained at a certain level or more to prevent bursting of the rip portion of the rotor core during high-pressure casting.

Among the conventional methods of casting a rotor, the centrifugal casting method shows a high filling rate and excellent efficiency, but has a problem that it cannot be applied universally, and the vertical high-pressure casting method using a vertical injection method has an ingate into which molten metal is injected on one side. As the air bubbles are isolated and distributed in the non-ingate part of the rotor due to bias, the imbalance of the rotor occurs, resulting in vibration noise and reduced efficiency. The horizontal high-pressure casting method using the horizontal injection method Although the rotor can be manufactured at a low production cost by using low-cost equipment and the amount of aluminum consumed is small, there is a problem in that the filling rate is lower than other manufacturing methods.

As described above, looking at the vertical high-pressure casting method and the horizontal high-pressure casting method, there is a problem in that pores are generated in the conductor bar and the end ring in the die casting process. On the other hand, it is essential to manufacture a mold in the die-casting process, and in the case of Cu die-casting, the lifespan is very short due to high temperatures, resulting in a high manufacturing cost.

Patent Publication No. 10-0572581 is a vacuum gravity mold casting machine that melts aluminum or copper alloy metal, etc. and introduces it by the weight of the molten metal into a mold in a vacuum state so that bulky products can be molded. do.

Republic of Korea Patent Registration No. 10-0572581 "Vacuum Gravity Mold Casting Machine" (2006.04.24.)

An object of the present invention is to solve the above problems, instead of the existing die casting process, the rotor core in which the conductor bar is assembled is placed in a simple mold manufactured in two stages, and the aluminum melt is supplied to the end ring by gravity casting method. It is characterized by proposing a method of manufacturing a rotor so that the part can be molded.

In the present invention, the steps of combining the tin-plated conductor bar and the rotor core, the step of assembling by putting the rotor core with the conductor bar coupled into a simple mold, and supplying an aluminum melt to both sides of the rotor core after the assembly is completed. It is characterized in that the rotor is formed through the step of forming the end ring by gravity casting and the step of manufacturing the rotor for the final induction motor by separating the simple mold after performing gravity casting.

A process for manufacturing an induction motor rotor according to the present invention for achieving the above object includes forming a rotor core by laminating a plurality of punched circular steel plates; coupling a plurality of conductor bars on the inside of a plurality of slots formed inside an outer circumferential surface of the rotor core; arranging the rotor core coupled with the plurality of conductor bars in a simple mold separated from the top and bottom; forming end rings on both sides of the rotor core by a gravity casting method by supplying aluminum through the simple mold; and separating the simple mold to obtain a completed rotor core.

The plurality of conductor bars may preferably be plated with tin.

The simple mold 100 includes a lower mold 110 and an upper mold 120 having a shape corresponding to the lower mold, and the upper mold and the lower mold have a core seating for enabling the rotor core to be installed. A portion is formed, and a melt supply line disposed on both sides of the core seating portion and a melt injection path 150 disposed for supplying aluminum molten solution between lower ends of both sides of the core seating portion and the melt supply line, and the core seating portion An overflow conduit 160 is formed on both upper ends and on the outer side of the simple mold to control the excessive supply of the aluminum melt supplied to the rotor core, and the melted aluminum is supplied through the melt supply line and the melt injection passage. It may be preferable to supply onto a simple mold and mold the end rings on both sides of the rotor core by gravity casting.

According to the present invention, all of the objects of the present invention described above can be achieved.

The present invention is a manufacturing method that allows the end-ring portion to be molded by gravity casting by supplying an aluminum melt in a state in which a rotor core assembled with a conductor bar is placed in a simple mold made of two upper and lower stages instead of the existing die casting process provides

Since the method for manufacturing a rotor for an electric motor according to the present invention inserts a conductor bar into the rotor core, the electrical conductivity is higher than that of the die-casting process, so the rotor efficiency is improved, and the manufacturing cost of the simple mold is relatively low compared to the die-casting device. , It is possible to produce small quantities, it is possible to manufacture a large rotor production capacity according to the production size of a simple mold, it is easy to manufacture rotors for various induction motors, and there are no restrictions on the thickness of ribs.

Unlike the existing die casting process, the present invention casts the end ring after inserting the conductor bar into the rotor core, and in the case of the conductor bar, tin plating is performed to prevent oxidation during casting, to cast different materials, and to improve bonding. there is.

1 (a) (b) is a description example of a rotor core and conductor bar components for manufacturing a rotor before gravity casting of the rotor with a simple mold according to an embodiment of the present invention.
The shape of the conductor bar manufactured on FIG. 1 (c) shows that it was processed by giving a hole, notch, multi-stage shape, etc. to increase the strength and joint area of the heterojunction at both endrings.
2 shows a coupling relationship in a state in which a conductor bar is press-fitted into a plurality of slots radially penetrating with respect to the center of the rotor core.
3 shows an assembly shape of the inner core for the mold and the inner core for the mold in the rotor.
4 shows a simple mold having a pair of symmetrical shapes of a lower mold and an upper mold.
5 shows a mold in which a melt runner is formed on one side with respect to the core seating part.
6 shows a method for manufacturing a rotor for an electric motor according to the present invention.
7 is a comparison of efficiency between a case in which a conventional die casting method is applied and a case in which a vacuum brazing method for a motor rotor according to the present invention is applied.

Hereinafter, the configuration and operation of an embodiment of the present invention will be described in detail with reference to the drawings. A process of gravity casting a rotor for an electric motor according to the invention using a simple mold will be described.

First, referring to FIG. 1, a rotor core 10 and a conductor bar 20, which are components for manufacturing a rotor for an electric motor, are prepared.

The rotor core 10 works by punching out a plurality of circular electrical steel sheets.

A plurality of slots 12 are radially formed through the rotor core 10 with respect to the center 11 of the rotor core. Each of the plurality of slots 12 may have a shape in which the width gradually increases from the center 11 of the rotor core toward the outside along the radial direction.

The conductor bar 20 is formed to correspond to the shape of the slot 12 but is longer than the entire length of the rotor core 10, so when the conductor bar 20 is inserted into the slot 12, It has a structure exposed to the inside and outside of the electronic core 10. In addition, the part connected to the endring part of the conductor bar is manufactured by processing it by making a hole or giving a notch or multi-stage shape to increase the strength and joint area of the heterojunction.

On the rotor core 10, the extruded conductor bar 20 is press-fitted and inserted into a plurality of slots 12 radially penetrating with respect to the center of the rotor core.

The end ring 30 is necessary to make the magnetic field of the iron core of the rotor core 10 a closed loop on the induction motor, and generates an independent electromagnet due to the magnetic field received from the field.

The end ring 30 has a donut shape so as to entirely cover the conductor bar 20 exposed through both ends of the rotor core 10, and on the inner surface of the end ring 30, the conductor bar 20 An insertion groove is formed to the extent that insertion of the end of the is possible.

3 shows a shape in which an inner core for a mold is assembled on the center of a rotor into which a conductor bar is press-fitted and inserted.

Referring to FIG. 4 , the simple mold applied to the present invention is designed so that both end-rings can be molded after being manufactured in two stages, instead of a die-casting process.

Looking at the simple mold in detail, it is as follows. Simple mold refers to all molds that can be manufactured in two stages, other than sand and casting molds.

The simple mold 100 includes a pair of a lower mold 110 and an upper mold 120 having symmetrical shapes, and each of the upper mold 120 and the lower mold 110 rotates in a state where a conductor bar is inserted. A core seating portion 130 enabling the seating of the electronic core is formed.

The core seating part 130 has a semi-cylindrical shape in which the rotor core 10 can be inserted, and the assembly of the inner core 133 for a mold that adjusts the stable assembly of the rotor core and the width of the endring shape. space 132. The rotor assembled with the inner core for the mold is seated on the core seating part 130 .

Meanwhile, in order to supply molten aluminum to form an end ring by gravity casting, melt runners 140 are formed on both sides of the core seating portion 130 as a reference. That is, the melt supply line runner 140 is disposed in a spaced apart state on the outside of the inner core assembly space for the mold of the buffer space 132 disposed on both sides of the core seating part.

Meanwhile, referring to FIG. 5 . The melt runoff 140 may be formed on one side of the core mounting portion 130 .

The melt runner 140 extends inward from the outer open areas of the upper mold and the lower mold to reach the lower portion of the core seating part. That is, the pair of melt runners 140 may extend from the upper side of the core seating portion 130 and face each other on the lower side of the core seating portion. The pair of melt runners may have a shape that is bent in such a way that they come close to each other at the lower side of the core seating part in a state in which they extend in a straight line outside the upper and lower molds.

Meanwhile, melt gates 150 for supplying aluminum melt are formed between lower ends of both sides of the core seating part 130 and the pair of melt runners 140 . That is, the melt supplied through the melt runner 140 is supplied to both ends of the rotor core 130 in a gravity casting method to form the end ring 30 by covering the coupled conductor bars.

On the other hand, on the tops of both sides of the core seating part 130 and on the outer sides of the upper and lower molds, gaskets 160 can be well filled with molten metal while removing gas generated inside when the aluminum melt supplied to both ends of the rotor core is injected. ) to form The gasket 160 enables the discharge of gases and foreign substances generated in the process of forming the end ring, and as a result, the quality of the end ring can be improved.

A plurality of guide holes 170 are formed on the lower mold and the upper mold, respectively. A guide bar 180 is coupled to interconnect a plurality of guide balls. That is, the lower mold and the upper mold achieve accurate occlusion by allowing guide bars to be coupled through mutually corresponding guide holes.

Referring to FIG. 6, a method of manufacturing a rotor for an electric motor will be described.

First, the rotor core 10 and the tin-plated conductor bar 20 are coupled.

After inserting the combined rotor core and the conductor bar 10 into the inner core 133 for a mold, insert it into the simple mold 100 to proceed with assembly. The rotor core coupled with the conductor bar is inserted on the core seating part formed in the lower mold of the simple mold, and the guide bar is coupled through a guide hole formed to correspond to the lower mold and the upper mold, thereby achieving accurate occlusion.

A riser 190 is disposed on the melt runner 140 forming the lower mold and the upper mold. The riser 190 is installed to increase the load of the molten metal so that gravity forming can be performed better. The riser 190 includes a funnel-shaped supply case 191 formed in an exposed structure on the outer open areas of the upper mold and the lower mold, and a supply pipe 193 extending in a communication structure on the lower end of the supply case.

After assembly is completed in a state in which the riser 190 is placed between the lower mold and the upper mold, molten aluminum is supplied onto the simple mold and molded by gravity casting.

After performing gravity casting, the simple mold is separated.

Finally, the rotor for the induction motor is manufactured.

7 is a comparison of efficiency between a case in which a conventional die-casting method is applied and a case in which a method for manufacturing a rotor for an electric motor according to the present invention is applied.

In a 2.2 kW class three-phase induction motor, the stator was used in common, and the motor performance was evaluated by replacing the rotor manufactured by die casting with the rotor manufactured by the proposed gravity casting process.

In comparison, it can be seen that the ETA efficiency of the rotor manufactured by the gravity casting process proposed according to the present invention is about 1% higher than that of the rotor applied with die casting at a rated power of 2.2 kW.

The rotor manufacturing process constituting the conventional induction motor melts an ingot into molten metal, inserts the rotor core into a mold made of die casting equipment, injects molten metal, and then manufactures it through a post-processing process. There are limitations in that a large amount of rotor rotor must be consumed due to minimum test die-casting for condition setting and that post-processing is essential to prevent bursting of the rotor core lip during high-pressure casting.

Since the method for manufacturing a rotor for an electric motor according to the present invention inserts a conductor bar into the rotor core, the electrical conductivity is higher than that of the die-casting process, so the rotor efficiency is improved, and the manufacturing cost of the simple mold is relatively low compared to the die-casting device. , It is possible to produce small quantities, it is possible to manufacture a large rotor production capacity according to the production size of a simple mold, it is easy to manufacture rotors for various induction motors, and there are no restrictions on the thickness of ribs.

Although the present invention has been described through the above examples, the present invention is not limited thereto. The above embodiments may be modified or changed without departing from the spirit and scope of the present invention, and those skilled in the art will recognize that such modifications and changes also belong to the present invention.

10: rotor core
20: conductor bar
30: end ring
100: simple mold
110: lower mold
120: upper mold
130: core seating part
132: assembly space of inner core for mold
133: inner core for mold
140: melt runner
150: melt gate
160: gasket
170: guide ball
180: guide bar

Claims (3)

forming a rotor core by laminating a plurality of punched circular steel plates;
coupling a plurality of conductor bars on the inside of a plurality of slots formed inside an outer circumferential surface of the rotor core;
arranging the rotor core coupled with the plurality of conductor bars in a simple mold separated from the top and bottom;
forming end rings on both sides of the rotor core by a gravity casting method by supplying aluminum through the simple mold; and
Characterized in that, the induction motor rotor manufacturing process comprising the; step of obtaining a completed rotor core by separating the simple mold.
According to claim 1,
The plurality of conductor bars are characterized in that tin is plated,
Induction motor rotor manufacturing process.
According to claim 1,
The simple mold 100 includes a lower mold 110 and an upper mold 120 having a shape corresponding to the lower mold, and the upper mold and the lower mold have a core seating for enabling the rotor core to be installed. part is formed,
A melt gate 150 disposed on both sides of the core seating part and between lower ends of both sides of the core seating part and the melt runner, and a melt gate 150 disposed on both sides of the core seating part and a simple mold A gasket 160 is formed on the outer side of the rotor core to remove foreign substances and gases generated during gravity casting of the aluminum melt supplied to the rotor core.
The induction motor rotor manufacturing process, characterized in that by supplying the molten aluminum through the melt runner and the melt gate onto a simple mold to form end rings on both sides of the rotor core by a gravity casting method.

Images