JP2692507B2 - Squirrel cage rotor manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squirrel cage rotor for high performance motors.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a squirrel cage rotor for a general motor is formed by laminating and fixing a plurality of rotor core pieces 1 having slots of a fully closed type or a fully opened type with a shaft 10 to form a circle. A columnar rotor core 6 is manufactured, and aluminum or aluminum alloy as a conductive material is pressure-cast into a cavity in a slot of the rotor core 6 and a cavity of left and right end rings at both ends of the rotor core to be molded, Finally, the outer peripheral portion of the rotor core 6 and the left and right end rings were machined to produce a cage rotor. This pressure casting method has a fixed mold 12 and a movable mold 11, and the movable mold 11 has a cavity in which the rotor core 6 is mounted and is positioned by a shaft 10. After that, the movable mold 11 and the movable mold 11 are movable. Mold 11
The mold is clamped with and the rotor conductor 5 and the left and right end rings 3, 4
The conductive material to be used is melted by another melting device (not shown), and the required amount is pumped out in a container and pressure cast from the injection port 15 of the sleeve 14, and is pushed by a plunger 16 equipped with a tip 17 at high pressure and high speed. , Rotor core 6
The conductive material melted in the left and right sides of the rotor conductor 5 and the rotor iron core 6 in a short time in the slot was made to flow from the gate 18 and injected.

[0003]

In the conventional pressure casting apparatus, since the molten conductive material is injected at a high pressure in a short time and injected into the inside of the slot or the like, the inside of the sleeve 14 and the inside of the slot 2 of the rotor iron core 6 are already formed. Since there is air in the mold etc., the width of the pressing surfaces of the fixed mold 12 and the movable mold 11 at the time of injection is about 0.2.
The air cannot be completely discharged only by the air discharge groove 22a of mm, air is entrained in the conductive material, and when the conductive material is solidified and contracted, a shrinkage cavity is formed in the central portion of the rotor conductor 5 and the left and right end rings 3. Internal defects were inevitable in the center of No.4 and No.4. Moreover, the molten conductive material penetrates between the rotor core pieces 1 forming the rotor core 6, so that the rotor conductor 5 is short-circuited.

[0004] The cage rotor for a motor manufactured in this manner is disadvantageous not only in strength at high speed but also in strength due to internal defects, and also in inferior in motor performance due to torque reduction due to short-circuit of the rotor conductor. It becomes an obstacle to the efficiency improvement of the motor. In addition, if the conductive material is aluminum, the specific resistance is high, which causes the temperature of the motor to rise, and it is difficult to miniaturize the motor.In particular, when used in a vacuum, high heat is transmitted to the motor rotating shaft or bearings, making high-speed rotation difficult. It was Therefore, even if the conventional pressure casting method using copper or copper alloy having a smaller specific resistance than aluminum is used, voids and shrinkage are generated inside the rotor conductor and the left and right end rings as in the case of aluminum pressure casting. Since casting defects such as cavities occur, in order to solve this problem, for example, as in JP-A-62-77041 and JP-A-62-100152, the left and right end rings are formed during or after the rotor conductor and the end rings are cast and formed. Pressing has also been proposed. However, although this method is effective for relatively large casting defects, it cannot completely crush small defects and has little effect of improving the density and decreasing the resistance value. In this pressing process, a large load is applied from both ends of the end ring parallel to the axis of rotation, and pressure is applied, so that the cage rotor is deformed and the rotor core piece is displaced. It is difficult to eliminate casting defects such as voids, shrinkage cavities and the like once formed by casting.

The present invention eliminates the above drawbacks, prevents air entrapment in the slots and end rings, and eliminates casting defects due to voids and the like.

[0006]

Above object In order to achieve the above, the rotor core pieces formed slots, child laminated rotor core pieces
The rotor core consisting of and melts in the slots of the rotor core.
By injecting the conductive material
Forming a rotor with an end ring formed
In order to achieve this, in a cage-shaped rotor manufacturing apparatus having a movable die for housing the rotor core and a fixed die for clamping the movable core together with the movable die, a pressing die for axially pressing the rotor core against the movable die. And a cylindrical inner press die and a cylindrical outer press die are provided concentrically with each other, and between the inner press die and the outer press die, a molten conductive material is injected into a slot of the rotor core. At this time, there is a cylindrical gap that serves as an air discharge groove in the slot.
The inner die and the outer die so that they are located on the end face in the direction
It is achieved by Rukoto configure.

[0007]

In the present invention, the movable die is provided with a pressing die for axially pressing the rotor core, and the pressing die is formed by concentrically providing a cylindrical inner pressing die and a cylindrical outer pressing die, and Between the outer die and the outer die, a gap is formed to serve as an air discharge groove for the air inside the cavity when the molten conductive material is injected into the cavity of the rotor core, so that the air inside the slot and end ring is discharged through the gap. However, it is possible to prevent air from being entrained by the conductive material and eliminate casting defects such as voids.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS.

FIG. 1 is a schematic explanatory view of a pressure casting apparatus showing an embodiment of the present invention, FIG. 2 is a sectional view of a rotor core 21 fixedly laminated on a shaft 10, and FIG. FIG. 7 is a partially enlarged view showing an insulating layer 9 provided on the inner surface of the slot 2. 4 is a sectional view of the cage rotor 8 obtained by the manufacturing apparatus of the present invention, and FIG. 5 is a side view of FIG.

In the squirrel cage rotor 8 of the present invention, a rotor core piece 1 having a slot 2 is aligned by a shaft 10 so as to pass through a slot 2 of a rotor core 6 in which a plurality of rotor core pieces 1 are laminated. The rotor core 6 provided with the insulating layer 9 formed by immersing in a phosphate treatment bath at 70 to 80 degrees for about 30 minutes also has the function of adjusting the product thickness of the fixed die 12 and the rotor core piece 1. The movable die 11 with the air discharge groove 22b is tightly tightened by the outer die 23 and the inner die 13, and the conductive material of copper or copper alloy melted in the non-oxidizing atmosphere is pressure-cast to form the rotor conductor 5 in the slot 2. And the left and right end rings 3 and 4 are integrally molded at the same time,
Finally, the squirrel cage rotor, which has been machined to secure the dimensions, is shown in FIGS. 4 and 5. In this squirrel cage rotor 8, the outer circumference of the rotor core 6 is ground to the dotted line 25, so that the rotor conductor 5 is fully open. Although not shown here, it is further advantageous in terms of strength by forming a taper between the round portion and the square portion of the slot 2.

In the manufacturing process of the squirrel-cage rotor 8, first, a rotor core piece 1 having a fully closed or fully open slot 2 is formed.
Are pierced by a shaft 10 so as to penetrate a slot 2 of a rotor core piece 1 which is fixedly laminated to a predetermined thickness, and the slots are aligned in parallel with the central axis or skewed at a certain interval. An insulating layer 9 capable of withstanding the temperature of the melted conductive material is provided on the inner surface to form a rotor core kumi as shown in FIG. The insulating layer 9 at this time is formed, for example, by immersing the cage rotor 8 in a phosphate bath at 70 to 80 degrees for about 30 minutes. Using a heating device such as another electric furnace
Preheat to 50 ° C. Next, the conductive material of copper or copper alloy is previously melted in another melting device. In this case, the atmosphere at the time of melting is made non-oxidizing in nitrogen gas or argon gas so as not to impair the mechanical characteristics and the electric characteristics of the conductive material, and is melted uniformly at a melting temperature of 1100 to 1250 ° C.
The preheated rotor core core is positioned and inserted into the cavity of the movable mold 11 by the shaft 10. A heating source such as a heater is attached to the movable mold 11 and the fixed mold 12, and the mold preheating temperature is heated to 200 to 850 ° C. Here, in the fixed mold 11 and the movable mold 12, At the same time when the mold is clamped with a force of 80 to 100 tons, the hydraulic device 24 is actuated, and the outer pressing die 23 and the inner pressing die 13 which are interlocked with the hydraulic device move in the direction of the arrow in FIG. 1 to cause the clearance of the rotor core piece 1. The laminated thickness of the rotor core 6 is adjusted so that it does not exist. At this time, the pressing force of the hydraulic device 24 is preferably 500 kg to 800 kg. Like the mold, the sleeve 14 is also equipped with a heating source such as a heater so that it can be preheated, and the preheating temperature is 200 to 1250 ° C. With the settings as described above, the molten conductive material required for one-time pressure casting is drawn in a ceramic container, and nitrogen gas or the like is blown onto the surface of the container to make it non-oxidized, and the injection port of the sleeve 14 is promptly added. in plan jar 16 fitted with a chip 17 is poured from the 15 gate the flow rate 10~50m
Eject so that it becomes / sec. At this time, the flow rate of the melted conductive material in the mold is set so that the conductive material is filled from the inside of the sleeve to the gate 18, and the area beyond the gate 18 is filled with air. There is. As the plunger further progresses, the molten molten conductive material first forms the right end ring 3, then the rotor conductor 5, and finally from the air discharge groove 22b between the outer die 23 and the inner die 13. At the same time as the air is completely expelled, the left end ring 4 is formed and the molten metal is completely solidified. The width of the air discharge groove 22b is 0.1 mm to 0.1 mm.
2mm is preferable.

There are no casting defects such as shrinkage cavities and voids inside the rotor conductor 5 and the left and right end rings 3 and 4 of the cage rotor manufactured in this way, and the gap between the rotor core pieces is No intrusion of conductive material was observed, and the insulating layer on the inner surface of the slot was also clearly present, and the rotor conductor and rotor core piece were completely insulated, reducing stray load loss and improving motor efficiency. . There is no particular problem with the insulating layer as long as it is an insulating material that can withstand the high temperature of molten copper as described above. For example, in addition to the phosphate coating described above, an alumina-based or zirconia-based ceramic coating may be used.

Here, the first feature of the movable die shown in FIG. 1 is that the rotor conductor and the left and right end rings have no casting defects and can be manufactured by preventing the conductive material from entering between the rotating core pieces. By providing the outer die and the inner die arranged inside, it is possible to have both the stacking thickness adjusting function and the air discharging function. Even for conductive materials with a large solidification shrinkage such as copper, the outer die and the inner die that have a stacking thickness adjustment mechanism work automatically following the solidification shrinkage of the conductive material, which is convenient for shrinkage cavities. Therefore, the casting defect is not formed. Since the air discharge groove is arranged on the circumference along the shape of the left end ring and is arranged along the molten metal flow direction, the air can be easily discharged.

A second feature is that a heating source such as a heater is provided inside the sleeve so that the molten metal temperature of the conductive material is not lowered as much as possible, and a heating source is similarly provided in the fixed mold and the movable mold. It is to improve the flowability. That is, by sufficiently keeping the temperature of the molten metal until the conductive material is molded from the melting device to the cage rotor, even the inside of the slot of 3 mm or less of the cage rotor for small motors can be uniformly filled. The preheat temperature of this sleeve is 20
For the preheating temperature of 0 to 1250 ° C. to 850 ° C., hot mold copper may be used, which is slightly higher than the tempering temperature, but can be dealt with without lowering the function as a mold.
Above this level, aluminum nitride ceramics having excellent heat resistance, heat crack resistance, and less metallurgical reaction with the conductive material are suitable. The fixed mold and the movable mold are preferably preheated at a temperature of 200 to 850 ° C. Similarly, since hot mold copper can be adopted, no large-scale equipment is required and the cost does not increase. This maximum heating temperature must match the preheating temperature of the rotor core of 850 ° C, and if it exceeds this temperature, the magnetic properties of the silicon-copper plate used for the rotor core piece deteriorates rapidly. ℃
It is necessary to keep it below.

A third characteristic of the pressure casting method is that the conductive material is melted in a nitrogen gas or argon gas in an unoxidized state, and the melting temperature is 1100-1.
That is to say 250 ° C. Further, all the space where the molten metal flows from the surface of the molten metal pumped out from the melting device and the inside of the sleeve to the inside of the cavity into which the rotor core core is inserted may be covered with the above gas. The melting temperature is the copper melting temperature (1083
1100 ° C. or higher, which is higher than 1 ° C.), and is suitable up to 1250 ° C. in view of the quality and workability of the molten metal. 1250 ° C
In the above case, oxygen, hydrogen and the like are easily mixed even though it is in the non-oxidized state.

Although the gade flow rate during pressure casting under such conditions is related to the size of the cage rotor,
50 m / sec is suitable. If it is 10 m / sec or less, solidification may occur in the middle of the small-diameter slot.
If it is longer than sec, the molten metal may be filled and air may be entrained before the air is discharged.

[0017]

As described above, according to the present invention, the movable die is provided with the die for axially pressing the rotor core, and the die is provided with the cylindrical inner die and the cylindrical outer die concentrically. In addition, between the inner die and the outer die, there is a cylindrical gap between the inner die and the outer die that serves as a discharge groove for air in the slot when the molten conductive material is injected into the slot of the rotor core.
And the gap is located on the axial end face of the end ring.
Since the inner pressing die and the outer pressing die are configured as described above, it is possible to prevent air from being entrained in the slots and the end rings, and to eliminate casting defects due to voids and the like.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a pressure casting apparatus showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a rotor core fixedly laminated on a shaft.

FIG. 3 is a partially enlarged view in which an insulating layer is provided on an inner surface of a slot of a rotor core piece.

FIG. 4 is a sectional view of a squirrel cage rotor obtained by the manufacturing apparatus of the present invention.

5 is a side view of FIG.

FIG. 6 is an explanatory view of a conventional pressure casting device.

[Explanation of symbols]

1 is a rotor core piece, 5 is a rotor conductor, 6 is a rotor core,
8 is a cage rotor, 11 is a fixed mold, 12 is a movable mold,
13 is an inner die, 22b is an air discharge groove, and 23 is an outer die.

Continuation of the front page (56) References JP-A 61-189858 (JP, A) JP-A 59-70453 (JP, A) JP-B 30-1760 (JP, B1)

Claims (2)

(57) [Claims] 1. A rotor core piece having slots formed therein,
A rotor core formed by stacking the rotor core pieces ;
Inject molten conductive material into the slot of rotor core
End rings formed at both ends of the rotor core by
And a movable mold for accommodating the rotor core to form a rotor having a ring and a fixed mold for clamping the movable mold together with the movable mold. The mold is provided with a pressing die that presses the rotor core in the axial direction, the pressing die is configured by concentrically providing a cylindrical inner pressing die and a cylindrical outer pressing die, and between the inner pressing die and the outer pressing die. Is provided with a cylindrical gap that serves as an air discharge groove for the air in the slot when the molten conductive material is injected into the slot of the rotor core.
With the inner pressing die so that it is located on the axial end face of the dring
An apparatus for manufacturing a squirrel cage rotor, comprising the outer die . Wherein said conductive material production apparatus of cage rotor according to claim 1 wherein copper or a copper alloy der wherein Rukoto.