JPH1141873A - Manufacture of cage rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of a cage rotor which does not give rise to the cavity in an end ring. SOLUTION: In this method the manufacture of a cage rotor is conducted, which accommodates stacked rotor cores 2 having a plurality of slots 5 and installs molds 9a and 9b between both ends in the thickness direction of stacked rotor cores 2 and the inwalls of split molds 10 and 11, and forms space to serve as end rings 7a and 7b to lead to the slots 5, and arranges a gate 91 to lead to one side 7a of the end ring formation part, and injects molten metal 13 of die cast material by high-pressure die cast method into the gate 91. In this case, a hole part 20 which has a minimum dimension width Wh, from two and a half to five times as large as the minimum dimension width Ws of the slot 5 is made such that at least one for leading to both end rings on the inside diameter side more than the slot part 5 of the rotor core 2, and a molten metal is injected towards the end ring part 7b on a side opposite via the slot part 5 and a hole part 20 from the end ring 7a on one side which has the gate 91.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a cage rotor of an induction motor, and more particularly to a method of manufacturing a cage rotor using high-pressure die casting.

[0002]

2. Description of the Related Art The structure of a squirrel-cage induction motor conventionally used generally is shown in FIG. The rotor 1 is configured by assembling a rotor core 2 and a conductor portion 3 integrally with a rotating shaft 4. The rotor core 2 is formed by laminating a large number of laminated cores 21 (iron core elements) made of a thin disk-shaped silicon steel plate as shown in FIG. 6 in order to prevent a loss due to eddy current. 5 is drilled. However, when the loss is not so important, a solid core, for example, a sintered compact may be used instead of the laminated core. The conductor portion 3 is integrally formed by casting an aluminum alloy or the like melted in the slot 5 by a high-pressure die-casting method while the laminated core 21 is tightened. Conductor part 3 formed by die casting
Is composed of a slot bar 6 arranged in a cage shape as shown in FIG. 7 and end rings 7 made of annular members at both ends. 8 and 9 are sectional views of a casting apparatus according to a conventional method of manufacturing a cage rotor by high-pressure die casting. FIG. 8 shows that the rotor core 2 is disposed between the split dies 10 and 11 of the vertical die casting machine as a casting device, and the rotor core 2 is fixed between the split dies 10 and 11 through a jig 12 therein. Have been. In addition, rotor core 2
Molds 9 for forming end rings 7a, 7b between both ends in the stacking direction and inner wall surfaces of split molds 10, 11.
a and 9b are provided, and a mold 9a is provided with a gate 91 communicating with the end ring 7a. Further, the molten metal 13 of the die-cast material is cast from a gate 91 provided in one of the molds 9a by a piston 8 provided below the rotor core 2. In such a configuration, the molten metal 13 that has passed through the sprue 91 fills the end ring 7a while a part of the molten metal 13 reaches the end ring 7b via the slot 5 and is filled. After the filling, the molten metal solidifies. Set. This method is the minimum dimensional width W _s of the slot 5 of the rotor core 2 is smaller than the end ring 7a, 7b minimum dimension width W _e of, after the molten metal 13 is filled, the first molten metal of the slot 5 solidifies, the piston 8 Pressure from the end ring 7b
Will not be transmitted. Then, since the gas dissolved in the molten metal 13 is released and at the same time contraction occurs when the gas changes from a liquid to a solid, a large nest is formed on the end ring 7b. For this reason, as shown in FIG. 9, a method has been proposed in which the slots 5 of the cage rotor and the end rings 7a, 7b at both ends are formed at one time by die casting (Japanese Patent Laid-Open No. Hei 6-133506). That is, the split mold 1
4, the rotor core 2 is housed therein, and the gate 9 communicates with the end rings 7 a, 7 b on both sides of the rotor core 2.
2 and 93 are provided in the molds 9a and 9b, and are poured into the gates 92 and 93 almost at the same time for die casting. Since the molten metal is poured into the end rings 7a and 7b on both sides almost at the same time and die-cast, the flow distance of the molten metal is less than half of the conventional one, and the die can be die-cast at low temperature and low pressure.

[0003]

However, the prior art has the following problems. (1) Even if the conventional method of die-casting the end rings on both sides almost simultaneously to solve the problem of nests generated on one end ring is used, there is a problem that defects due to nests occur on the end rings. Remains. Generally, when molten metal enters a mold, the temperature of the metal decreases and solidifies because heat is removed from the mold by heat conduction, but the solidification time is faster as the width of the mold gate is narrower. Minimum dimension width W _m is the end ring 7a of the sprue 92 and 93 of the mold 9, as shown in FIG. 9, those which are set to approximately half or less of the minimum dimension width W _e of 7b, sprue 92 and 93 of width Due to the small size, the solidification of the gates 92, 93 becomes faster, and as a result, nests are likely to be formed on the end rings 7a, 7b. As a result, if there is a defect in the end rings 7a and 7b, the weight of the conductor portion becomes unbalanced, so that the rotor is deformed by the centrifugal force applied at the time of rotation and the end ring nests are deformed to generate vibration, In addition, there is a problem that the end ring is damaged during rotation when it is severe. In addition, there is a possibility that heat is generated at a joint portion of the conductor portion and electric loss increases. For this reason, the method of die-casting almost simultaneously on the end rings on both sides has a problem that the quality of the electric motor is reduced due to the occurrence of nests and the reliability is impaired. (2) Compared to the conventional method of die-casting on both side end rings at the same time, the method of die-casting from one side has relatively few nests, but the die-casting die is not provided because the gate is provided on both sides. There is a problem that the mold becomes complicated and the mold cost increases. Then, after filling the molten metal, there is an operation of cutting off the sprue portion to take out the rotor core. However, if there is a sprue on both sides of the rotor core, this operation cannot be automated, so that a problem has arisen in productivity. Thus, there has been a demand for a method of die-casting from one side of the rotor and a method in which burrs do not occur at the end ring portion. In order to solve the above-mentioned problems, the present invention has as a first object to perform die casting on end rings on both sides of a cage rotor at substantially the same time. An object of the present invention is to provide a method of manufacturing a highly reliable cage rotor, which does not cause deterioration in quality. Further, as a second object, in die-casting from one end ring of the cage rotor, the cost of the mold is low, the work of separating the gate section can be easily performed, and the deterioration of the quality due to the generation of the end ring nest is reduced. It is an object of the present invention to provide a method of manufacturing a highly reliable cage rotor that does not occur.

[0004]

In order to solve the above problems, the present invention has the following method. (1) According to the present invention, a laminated rotor core having a plurality of slots on an outer periphery is housed in a split mold, and both ends of the rotor core in a stacking direction and the split are provided. A mold is installed between the mold and the inner wall surface, a space serving as an end ring communicating with the slot is formed, and a sprue communicating with each of the end ring forming portions is disposed. In a method of manufacturing a cage rotor in which a molten metal of a die cast material is poured almost simultaneously by a die casting method and the slot and the end ring are integrally formed in a cage shape, the minimum dimension width of a gate for pouring the molten metal is set as described above. It is at least 0.7 times the minimum dimension width of the end ring. The die cast material is made of aluminum or an aluminum alloy. (2) According to a second aspect of the present invention, a solid or laminated rotor core having a plurality of slots on its outer periphery is housed in a split mold, and the length or the thickness direction of the rotor core is increased. A mold is installed between both end portions of the mold and the inner wall surface of the split mold, a space serving as an end ring communicating with the slot is formed, and a sprue communicating with one side of the end ring forming portion is provided. Then, a molten metal of a die cast material is poured into the sprue by a high-pressure die casting method, and the slot and the end ring are integrally formed in a cage shape. At least one hole having a minimum dimension width of 2.5 to 5 times the minimum dimension width of the slot so as to communicate with both end ring portions, and one end ring having the gate; It is to pouring the molten metal toward the end ring portion of the opposite side through the hole and the slot portion from. Further, the minimum dimension width of the hole is 0.7 times or more the minimum dimension width of the end ring. The die cast material is made of aluminum or an aluminum alloy.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a diagram showing a configuration of a rotor unit set in a vertical die casting machine used in a first embodiment of the present invention. FIGS. 2A and 2B are diagrams showing the shape of the gate. Here, the same or corresponding parts as those in the conventional example of FIGS. 8 and 9 are denoted by the same reference numerals. In this embodiment, the rotor core 2 is housed between the split molds 10 and 11 of the vertical die casting machine with the thickness direction of the rotor core 2 being horizontal in FIG. The tool 12 is fixed in a state where it is inserted, and the end ring 7a,
7b are provided with dies 9a and 9b, respectively.
A die 9c is provided between the piston 9 and the piston 8 provided vertically below the die 9c. The die 9c is provided with a gate 91 communicating with the end rings 7a and 7b. The configuration is such that a molten metal 13 of a die cast material is cast into a slot 5 of a rotor core 2 from a gate 91 of a mold 9c by a piston 8. In such a method of pouring the slot 5 of the rotor core 2 and the end rings 7a, 7b on both sides thereof almost simultaneously by die casting,
The minimum dimensional width W _m of the cast molten metal 13 sprue 91, end rings 7a, the dimensional ratio W _m / W with minimum dimensional width W _e of 7b
_{When e} was X, the experiment was conducted with various values of X.
Shape W _m of one sprue 91, and X × 40 mm, the maximum is the same as the minimum dimension width W _e of the end ring. Also,
Aluminum and an aluminum alloy were used as the die cast material. Next, the optimum shape of the gate 91 was grasped by actually using this die casting machine. The die casting machine was 1000 tons, the molten metal temperature was 700 ° C., the casting speed was 3 m / s, the rotor was a laminate of silicon steel plates, the rotor core 2 was 450 mm in diameter, and the stacked thickness was 690 mm, and the rotor was die cast. Gates 91 are arranged at equal intervals in six places around the circumference of the rotor core 2. Subsequently, after die casting, the condition of the nest was examined by X-ray radiography of the end ring. Table 1 shows a comparison of the nest size with respect to the minimum dimensional width ratio X between the gate and the end ring in this embodiment and a conventional example (a method of casting from one end ring).

[0006]

[Table 1]

[0007] From this, it was confirmed that the end ring in which nests are more likely to be formed than in the conventional example has fewer nests. In addition, a product with less nests was obtained as the width of the gate was closer to the width of the end ring. In particular, it was confirmed that almost no nests were formed when X was 0.7 times or more.

[0008] According to the manufacturing method of this embodiment, the minimum dimension width W _m is the end ring 7a of the sprue 91 of the mold 9c as shown in Figure 1, more than about 0.7 times the minimum dimension width W _e of 7b When the slot 5 and the end rings 7a and 7b on both sides are poured almost at the same time by die casting, the solidification time of the end ring and the spout 92 are smaller than those of the conventional sprue and end ring having the minimum dimension width ratio. , 93, the difference in coagulation time is reduced so that both parts are deprived of heat at the same rate and cool down, so that no nests form on the end rings 7a, 7b. In addition, since no defect of the nest is generated on the end rings 7a and 7b, the imbalance of the weight of the conductor is eliminated, and the rotor may be deformed by the centrifugal force to generate vibration. ,
The problem of breakage during rotation does not occur, and furthermore, there is no increase in electrical loss due to heat generation at the joint of the conductors. As described above, in the method of die-casting the end rings on both sides almost at the same time, since nests do not occur, a high quality and highly reliable product can be obtained as the electric motor. In addition, the die-cast material of this embodiment may be, for example, a copper alloy or a magnesium alloy, in addition to aluminum and an aluminum alloy.
The shape of the sprue 91 is assumed trapezoidal rectangular or (b) shown in FIG. 2 (a), and the average value W _m of the minimum width portion in the case of (b). The shape of the sprue is not limited to these, and other shapes may be used. The vertical direction of the rotor core is set horizontally in the vertical die-casting machine, and the rotor core is fixed and stored between the divided molds. It may be stored vertically between the split molds.

Next, a second embodiment of the present invention will be described. FIG. 3 is a view showing a configuration of a rotor unit set in a vertical die casting machine used in the second embodiment of the present invention. A hole 20 connected to both end rings is formed on the inner diameter side of the rotor core. (A), (b),
(c) is a diagram showing the shape of the hole. In this embodiment, FIG.
In the above, the rotor core 2 is housed between the split molds 10 and 11 of the vertical die casting machine, and fixed with the jig 12 inserted through the center of the rotor core 2 and the end rings 7a and 7
b are provided with molds 9a and 9b, respectively, and the mold 9a is provided with a gate 91 communicating with the end ring 7a. The configuration is such that the molten metal 13 is cast by the piston 8 from the gate 91 of the mold 9a to the end ring portion 7b on the opposite side from one end ring 7a having the gate of the rotor core 2 via the slot 5 portion. . In the method of pouring by such a die casting method, both end ring portions 7a, 7
forming a hole 20 through which the molten metal 13 passes so as to communicate with b.
The minimum dimensional width W _h of the hole 20, if the dimensional ratio W _h / W _s of the minimum dimension width W _s of the slot 5 parts was Y, end rings 7a, for the minimum dimension width W _e of 7b Casting experiments were performed with various values of Y. If set to 1 W _s in the experiments, W _e used a rotor 5 times the dimension of W _s. Aluminum and an aluminum alloy were used as the die-cast material. Next, the optimum shape of the hole 20 was grasped by actually using the die casting machine. Die casting machine: 1000 tons, molten metal temperature: 720 ° C, pouring speed: 3m / s, rotor: laminated silicon steel sheet, rotor core diameter: 450mm, stack thickness: 690mm
As a die cast. The hole 20
Are arranged at equal intervals at six locations around the circumference of the rotor core 2. Subsequently, after die casting, the end ring 7b was examined for the state of the nest by X-ray transmission photography. Table 2 shows the porosity generation ratio with respect to the minimum dimensional width ratio Y of the hole and the end ring in the present example and the conventional example (a method in which the hole through which the molten metal passes through is not provided in the inner diameter portion of the rotor core and the casting is performed from one side). The following shows a comparison. Y is 5 samples is the minimum dimensional width W _e of the minimum dimension width W _h and the end ring portion of the hole is the same.

[0010]

[Table 2]

[0011] Thus, the molten metal 1
3, the minimum width of the hole 20 is 2.5 to 5 times smaller than the minimum width of the hole of the slot 5.
In the example of the present invention twice, it was confirmed that the end ring 7b, in which the nest is more likely to be formed than the conventional example, has less nest. In addition, 0 minimum size width W _h of the hole is the minimum size width W _e of the end ring.
It was confirmed that a product with almost no nest could be obtained when the size was 7 times or more. Since the casting is performed from one side of the rotor core, the mold is not complicated and the gate is easily removed as compared with the method of casting from both sides.

According to the manufacturing method of the present invention in this embodiment, solidification starts after the molten metal 13 entered from the gate 91 fills the product, but the slot portion 5 having the smallest dimensional width is obtained.
Even if solidified, hole 2 with minimum dimension width larger than slot
Since the molten metal in 0 is not completely solidified, the pressure from the piston is applied to the counter end side ring 7b, and the molten metal is also replenished. As the minimum dimension width of the end ring portion and the hole portion is closer, the solidification time of both portions is closer. Therefore, the molten metal is replenished from the hole portion until the end ring portion is completely solidified, and no nest is formed.
In addition, since there is no nest defect in the end rings 7a and 7b, the imbalance in the weight of the conductor portion is eliminated, and the rotor is deformed by centrifugal force to generate vibrations or to rotate. There is no problem of breakage inside, and furthermore, heat generation does not occur in the joint portion of the conductor portion, and the electric loss does not increase. Further, since the molten metal is cast from one side of the rotor as in the conventional example, the mold structure is not complicated, and the gate can be separated by the conventional operation. As described above, in the die-casting method of the present invention, since nests do not occur, a high-quality and highly reliable product can be obtained as an electric motor. The die-cast material may be, for example, a copper alloy or a magnesium alloy in addition to aluminum and aluminum alloy, and is not limited to these. Since the number of the holes 20 may be determined so as not to affect the characteristics of the motor, it is preferable that at least one of the holes 20 is uniformly arranged in the circumferential direction of the rotor core 2. The shape of the hole 20 is a rectangular shape shown in FIG. 4A, a trapezoidal shape shown in FIG. 4B, and a circular shape shown in FIG. 4C. In the case of a trapezoidal shape, the average value of the minimum dimension width portion is W _h , for circular the diameter and W _h, but the shape of the hole is not limited to the above shape. Further, the rotor core is vertically fixed in the vertical die-casting machine, and the rotor core is fixed between the divided molds. It may be stored horizontally between the split molds.

[0013]

As described above, the present invention has the following effects. (1) In die-casting almost simultaneously to the end rings on both sides of the cage rotor, the minimum width of the mold gate is set to 0.7 times or more the minimum width of the end ring. To prevent defects due to nests and deterioration of quality due to vibration and heat generation,
There is an effect of obtaining a highly reliable cage rotor manufacturing method. (2) In die-casting from one end ring of the cage rotor, a hole having a minimum dimension width of 2.5 to 5 times the minimum dimension width of the slot is formed in the inner diameter portion of the rotor core. This has the effect of providing a highly reliable cage rotor manufacturing method that prevents defects due to the occurrence of nests and deterioration in quality due to vibration and heat generation. In addition, since the minimum dimension width of the hole is set to 0.7 times or more the minimum dimension width of the end ring, there is an effect that defects and the like due to generation of end ring nests do not occur.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a rotor unit set in a vertical die casting machine used in a first embodiment of the present invention.

FIG. 2 is a view showing a shape of a gate of FIG. 1;

FIG. 3 is a diagram showing a configuration of a rotor unit set in a vertical die casting machine used in a second embodiment of the present invention.

FIG. 4 is a view showing a shape of a hole in FIG. 3;

FIG. 5 is a perspective view showing a rotor structure of a conventional cage induction motor.

6 is a perspective view showing a state of the rotor from which the end ring of FIG. 5 is removed.

FIG. 7 is a perspective view showing the cage-shaped conductor of FIG. 5;

FIG. 8 is a diagram showing a configuration of a rotor unit set in a conventional die casting machine.

FIG. 9 is a diagram illustrating a configuration of a rotor unit set in another conventional die casting machine.

[Explanation of symbols]

1: Rotor 2: Rotor core 20: Hole 3: Conductor 4: Rotary shaft 5: Slot 6: Slot bar 7a, 7b: End ring 8: Piston 9a, 9b, 9c: Die 91: Gate 10, 11, Split mold 12: jig 13: molten W _m: minimum dimension of the sprue width W _e: minimum dimension of the end ring width W _h: minimum dimensional width of the hole

Claims (4)

[Claims] 1. A laminated rotor core having a plurality of slots on its outer periphery is housed in a split mold, and a space between both ends of the rotor core in a stacking direction and an inner wall surface of the split mold is provided. A mold is set up, a space serving as an end ring communicating with the slot is formed, and a sprue communicating with each of the end ring forming parts is arranged. In a method of manufacturing a cage rotor in which a molten metal is poured almost simultaneously and the slot and the end ring are integrally formed in a cage shape, a minimum dimension width of a gate for pouring the molten metal is set to 0 of a minimum dimension width of the end ring. 7. A method for manufacturing a cage rotor, wherein the ratio is 7 times or more. 2. A solid or laminated rotor core having a plurality of slots on its outer periphery is accommodated in a split mold, and both ends of the rotor core in the length or thickness direction and the split mold are provided. A mold is installed between the inner ring and the inner wall surface, a space serving as an end ring communicating with the slot is formed, and a sprue communicating with one side of the end ring forming portion is provided.
A method of manufacturing a cage rotor in which a molten metal of a die-cast material is poured into the sprue by a high-pressure die-casting method, and the slot and the end ring are integrally formed in a cage shape. At least one hole having a minimum dimension width of 2.5 to 5 times the minimum dimension width of the slot is formed so as to communicate with the end ring section, and the slot section is formed from one end ring section having the gate. And pouring the molten metal toward the opposite end ring via the hole and the hole. 3. The method according to claim 2, wherein the minimum dimension width of the hole is 0.7 times or more the minimum dimension width of the end ring. 4. The method according to claim 1, wherein the die cast material is aluminum or an aluminum alloy.