JP2001009560A - Die cast device for motor rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die cast device for a motor rotor with excellent productivity by preventing occurrence of misrun or shrinkage cavity and improving quality stably while utilizing advantages of casting molding with a die cast method. SOLUTION: One end of an inner hole 42 of a sleeve 41 engaged with an upper mold 22 coaxially with an end ring molding part 17 is opened on the upper face of the upper mold 22, and the other end is introduced to a radial runner 43 connected to the end ring molding part 17. A pressurizing piston 44 is reciprocatably inserted in the inner hole 42 in a manner that the tip end of the piston is faced to the runner 43 and the rear end is connected to a hydraulic cylinder 45, so as to perform pressurization after charging to the end ring molding part 17 on the opposite side of a gate. On the inner face at one end of the inner hole 42, plural grooves 47 opened to the upper face of the upper mold 22 are formed, and a cover 48 for forming a closed space surrounding the opening part on the upper face of the upper mold 22 is mounted. Then, a vacuum device 49 is connected to the cover, so as to reduce the pressure in the mold cavity before injection filling starts. Furthermore, the end on the lower mold 24 side of a shaft 11 inserted into a core iron 12 is held by a compressed spring, and a gate ring 52 is coaxially arranged to the end on the upper mold 22 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting apparatus for a motor rotor, and more particularly to an improvement in quality of a motor rotor formed by the die casting apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 3, a motor rotor 60 generally has a core core 6 formed by laminating many thin steel plates.
2, a thin rod-shaped conductor 65 formed in a large number of slot portions 64 cut out in the outer peripheral portion of the iron core 62;
And two annular end rings 66 and 67 which are formed at both ends and short-circuit the conductor 65.

FIG. 4 shows only a main part of a conventional die-casting apparatus which mainly forms a die 70 for casting and molding a motor rotor 60.
Attached devices such as a hot water supply mechanism and a product carry-out are not shown. In the figure, a mold 70 includes an upper mold 72 serving as a movable mold attached to a movable die plate 71, and a middle mold 7 in which the upper mold 72 is opened and clamped by a mold clamping mechanism (not shown).
3 and a fixed mold comprising a lower mold 74 on which the middle mold 73 is mounted. At the time of casting, the core core 62 is mounted on the middle mold 73 and the mold is clamped, so that the upper mold 72 and the lower mold 74 are attached to the end. A portion for forming the rings 66 and 67 and a number of slot portions 6 of the core iron core 62 attached to the middle die 73.
4 is formed. Lower mold 7
4 is a bolster 77 attached to a fixed die plate 76
It is slidably held on top. An injection sleeve 78 which penetrates the fixed die plate 76 and the bolster 77 and is opened on the upper surface side of the bolster 77 is provided.
4 and is connected to a sprue hole 79 formed in the same. The gate hole 79 of the lower mold 74 and the mold cavity 75 are connected to a runner (gate) 8.
It is communicated by 0. The injection sleeve 78 has, for example, an inner plunger 8 concentric with the outer plunger 81.
2 is inserted, and an injection mechanism including an injection cylinder (not shown) is connected. A hot water supply pipe 84 is connected to the lower side wall of the injection sleeve 78, and a molten metal such as aluminum is supplied from a hot water supply mechanism (not shown).

In order to cast and form a motor rotor using such a conventional die casting apparatus, a core iron core 62, which is formed by laminating a number of thin steel plates and fastened and fixed by a shaft 61, is set up, and a work moving device (not shown) is used. It is mounted on the middle mold 73, the mold clamping mechanism is operated to move the upper mold 72, which is a movable mold, forward to fasten the mold, and the injection sleeve 7 is moved by the hot water supply mechanism via the hot water supply pipe 84.
8, a predetermined amount of molten metal is supplied to the upper portion, the injection mechanism is operated to advance the injection plunger 83, and the molten metal is pressurized and filled into the mold cavity 75 through the sprue hole 79 and the runner 80. In this case, the outer plunger 81 is first advanced to complete the filling, and then the inner plunger 82 is advanced to perform pressure molding. After the molding is completed, the upper die 72 is retracted and opened, and the actuator attached to the lower die 74 on which the middle die 73 is placed is operated to slide on the bolster 77 so that the solidified portion of the sprue hole 79 is formed. Cut at Furthermore, the casting cycle is repeated by unloading the motor rotor cast from the middle die 73 using a work moving device and mounting a new iron core 62 on the middle die 73.

[0005]

By the way, the features of the casting by the die casting apparatus are that the productivity is good because the molten metal is filled at a high speed, the filling time is short, high pressure is applied, and the molten metal is cooled at a high speed. It is said to be suitable for mass production. However, in the case of the above-described die casting apparatus for a motor rotor, the state in which the molten metal supplied to the upper part of the injection sleeve 78 is filled into the mold cavity 75 by the advancement of the outer plunger 81 is determined by the spout hole 79 of the lower mold 74. End ring 6 of lower mold 74 via runner 80
6, the filling is performed so as to fill the slot 64 of the iron core 62 attached to the middle die 73, and finally to the end ring 67 forming portion of the upper die 72. Therefore, this upper mold 72 (anti-gate side) is inevitable.
However, there is a problem that the filling of the molten metal into the molded portion of the end ring 67 (running of the molten metal) tends to be deteriorated. Furthermore, after filling with the outer plunger 81, the inner plunger 82 is advanced to pressurize the molten metal during solidification while supplementing the filling, thereby preventing the occurrence of shrinkage cavities due to solidification shrinkage and entrapment cavities of air or hydrogen gas. However, the conductor 65 is formed in the thin rod-shaped slot portion 64.
However, the pressing force of the inner plunger 82 is not sufficiently applied to the end ring 67 forming portion of the upper die 72, which has a smaller heat capacity than the end ring 67 forming portion of the upper die 72 and solidifies earlier and solidifies later. There is a problem that shrinkage cavities easily occur in the molded portion of the 72 end ring 67. Depending on the type of the motor rotor, as shown in FIG. 3, many end rings 66 and 67 have cooling fins 68, and in this case, the above-mentioned problems of poor runoff and shrinkage cavities further occur. It will be easier.

FIG. 5 shows a mold apparatus proposed to prevent the occurrence of shrinkage cavities in the end ring of the motor rotor, and its structure and operation will be briefly described. FIG.
As shown in (a), the core iron core 92 before molding and the lower mold 95 are movably floated and held via compression springs 87, 88 and 89, and when the molten metal is filled, As shown in FIG. 5 (b), when the coagulation progresses,
First, solidification of the sprue 99 and the slot 94 of the iron core 92 having a small heat capacity progresses, and the pressing force from the injection plunger 93 to the sprue-side end ring forming part 96 is cut off, so that the lower die 95 floats. The compression spring 87 is contracted, and the lower mold 95 is moved toward the gate-side end ring forming part 96. Due to the synergistic action of the movement of the lower mold 95 and the progress of solidification of the slot 94, the gate-end-side end ring forming part 96 is reduced in volume and pressed, and at the same time, the compression springs 88 and 89 for floating the iron core 92. Is contracted, the iron core 92 is moved toward the counter-gate-side end ring forming section 97, and the counter-gate-side end ring forming section 97 is also reduced in volume and pressurized.

[0007] However, in the method in which the iron core and a part of the mold are floated as described above, and they are moved and condensed with the progress of condensing, the amount of movement depends not only on the solidification of the molten metal but also on the iron core. In addition, the molten metal easily enters the gaps on the outer periphery that allow the mold to move, and it is inevitable that the solidification deteriorates the mobility.It is also difficult to take countermeasures, and the finished shapes of both end rings vary. It is feared that there is a problem in mass-producing easy and stable products. In addition, it is not possible to cope with the problem of poor running of the hot water, which is likely to occur in the end ring having the cooling fins.

[0008] Therefore, an object of the present invention is to prevent the above-mentioned problems of poor running of the melt and shrinkage cavities easily while utilizing the advantages of casting by the die casting method, stably improve the quality, and improve the productivity. An object of the present invention is to provide an excellent motor rotor die casting apparatus.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to an upper mold for a core formed on an outer periphery of a laminated core for a core mounted on a middle die. And a mold cavity formed in the lower mold and an end ring forming portion formed in the lower mold, and an injection plunger inserted into an injection sleeve connected to a hot water supply mechanism to a mold cavity to be clamped from a sprue provided in the lower mold to a sprue end of the lower mold. In a motor rotor die-casting device which is filled with molten metal through a plurality of radial runners communicating with the ring forming portion, and is molded by pressurizing, the radial shape communicating with the counter gate side end ring forming portion provided on the upper die is provided. A plurality of runners, a sleeve having one end communicating with the runner and having the other end open to the outside of the upper mold, and a sleeve fitted into the upper mold, and slidably inserted through the inner hole; Provided outside the upper mold A pressurizing piston connected to the actuator, a plurality of grooves provided on the inner periphery on the other end side of the inner hole and opened to the outside, a cover for sealing the opening to the outside of the upper mold, and connected to the cover Before starting injection filling of the molten metal, the tip of the pressurizing piston is retracted to the position of the groove at the other end of the inner hole, and the vacuum device is operated to depressurize the inside of the mold cavity. After that, the tip of the pressurizing piston is advanced to the cutoff position of the groove, and the molten metal is injected and filled while maintaining the reduced pressure to prevent gas entrainment and poor running of the molten metal. The tip of the pressurizing piston is advanced and pushed into the molten metal that has reached the inner hole from the runner of the end gate forming part on the side of the gate, thereby pressing the end ring forming part on the side of the gate to prevent shrinkage cavities. Is characterized by That the die casting apparatus of the motor rotor.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a die casting apparatus for a motor rotor according to the present invention, which shows only a main part mainly including a mold 20 as in the case of the conventional apparatus shown in FIG. 3, and mold clamping, injection, and hot water supply provided in a normal die casting apparatus. The illustration of the mechanism and the attached devices such as the product unloading is omitted. In FIG. 1, a mold 20 includes an upper mold 22 which is a movable mold attached to a movable die plate (not shown), and a middle mold 23 and a middle mold 23 which are opened and closed by a mold clamping mechanism (not shown). And a fixed mold including a lower mold 24 to be placed. Medium 23
The core iron 12 having a large number of slots 14 is attached to the upper die 22 and the end dies 16 and 17 of the lower die 24 and the slots 14 are communicated with each other to form a mold cavity 25. . The lower mold 24 is slidably held on a bolster 27 attached to a fixed die plate 26. The injection sleeve 28 is fixed to the fixed die plate 26.
The bolster 27 is inserted through the bolster 27, and is connected to a gate hole 29 formed in the lower die 24. Gate hole 29 of lower mold 24 and mold cavity 25
Are communicated with each other by a hot water path 30. Injection sleeve 28
A double-type injection plunger 33 composed of an outer plunger 31 and an inner plunger 32 inserted concentrically is inserted therethrough, and is connected to an injection mechanism including an injection cylinder (not shown). Further, a hot water supply pipe (not shown) and a hot water supply mechanism are connected to a lower portion of the injection sleeve 28, and a molten metal such as aluminum is supplied. The scope of these basic configurations is
This is composed of well-known technical contents common to the corresponding members of the above-described conventional apparatus.

However, in the present invention, the following configuration is added in order to prevent the occurrence of gas entrapment cavities, poor runoff, and shrinkage cavities in the end gate forming portion 17 on the counter gate side. That is, the sleeve 41 is
2 is fitted concentrically with the end ring forming part 17, one end of the inner hole 42 is opened on the upper surface of the upper mold 22, and the other end is connected to a radial runner 43 communicating with the end ring forming part 17. A pressurizing piston 44 has a tip running into the inner hole 42.
And a rear end thereof is connected to a piston rod 46 of a hydraulic cylinder 45 serving as an actuator provided on the upper die 22. The actuator may be composed of a servomotor and a ball screw. The forward stroke of the piston rod 46 is controlled in at least two stages by providing a stroke sensor 50, for example. In addition, a plurality of grooves 47 that are open to the upper surface of the upper die 22 are formed in the inner periphery of one end of the inner hole 42 that opens to the upper surface of the upper die 22, and the piston rod 46 penetrates through a seal to seal the upper surface of the upper die 22. A cover 48 that forms a sealed space surrounding the opening is attached to the upper surface of the upper mold 22. A suction port is provided in the cover 48, and a vacuum device 49 for reducing the pressure inside is connected. Further, the shaft 11 into which the core 12 for the core is inserted is held by a compression spring 51 buried in a hole formed in the lower mold 24 at an end of the lower mold 24, and a gate ring 52 is formed at an end of the upper mold 22 by a gate ring 52. Are concentrically mounted by a positioning spigot or the like. The side of the gate ring 52 facing the iron core 12 is flat, and the side of the upper die 22 forms one side of a radial runner 43 communicating with the end ring forming part 17. Note that, when the cooling fin forming portion 18 is provided in the end ring forming portion 17, it is preferable that the radial runner 43 is provided so as to face the position thereof.

Next, the operation of the apparatus according to the present invention when casting is described. First, the core iron 12 having the gate ring 52 mounted thereon, which is inserted through the shaft 11 by setting up, is mounted on the middle mold 23, and the upper mold 2 is clamped by the mold clamping mechanism.
2 is advanced toward the middle mold 23 and the lower mold 24 and the mold 20
Is performed. At this time, the clamping force of the upper mold 22 acts directly on the gate ring 52 between the radial runner 43 and the runner 43, so that the gate ring 52 compresses the end of the shaft 11 via the shaft 11. By pressing the spring 51 and pressing the flat surface on the side of the iron core 12 against the lamination surface of the iron core 12, an appropriate core thickness and core pressing of the iron core 12 are maintained.

After the mold is clamped and before the injection filling of the molten metal into the mold cavity 25 is started, the tip of the piston rod 46 in the sleeve 41 provided on the upper mold 22 is moved to the position of the groove 47 as shown in FIG. To a state in which a radial runner (runner) 43 communicating with the sprue-side end ring forming portion 17 is conducted from the inner hole 42 of the sleeve 41 to the space in the cover 48 via the groove 47. By operating the connected vacuum device 49, the inside of the mold cavity 25 from the gate side end ring forming section 17 to the slot section 14 of the iron core 12 and the gate side end ring forming section 16 is evacuated and depressurized. In order to cut off the communication between the inner hole 42 of the sleeve 41 and the cover 48 while maintaining the state, the piston rod 46 is moved over the groove 47 as shown by the phantom line in FIG. By advancing to that position,
The inside of the mold cavity 25 is kept in a reduced pressure state.

The depressurized mold cavity 25
In the same manner as in the case of the above-described conventional apparatus, the molten metal supplied to the upper part of the injection sleeve 28 is operated to move the outer plunger 31 of the injection plunger 33 forward by operating the injection mechanism, and the gate hole 29 and the runner 30 Through mold cavity 2
5 is filled with the molten metal under pressure, so that the gate 30 to the gate-side end ring forming portion 16 and the slot 1 of the iron core 12 are filled.
The filling of the molten metal which reaches the end ring forming portion 17 on the side of the pouring gate via 4 is promoted by the decompression in the mold cavity 25, and prevents gas entrapment and poor running of the metal which are particularly likely to occur in the end ring forming portion 17 on the side of the pouring gate. can do. In addition, by forming a plurality of radial runners 30 from the gate hole 29 at the center of the lower mold 24 by shunts so as to communicate with the cooling fins of the gate side end ring forming part 16, the filling pressure of the molten metal is good. become. When the inner diameter of the injection sleeve 28 can be reduced, the cross-sectional area of the injection sleeve 28 is reduced, so that the casting pressure obtained from the injection pressure can be increased.

When the filling of the molten metal into the mold cavity 25 is completed, the completion state is detected by a signal detected by a detecting means (not shown), for example, a timer signal after a preset time has passed, the molten metal filled into the mold cavity 25. Is performed. FIG. 1 shows this pressurized state. In this case, as in the case of the above-described conventional apparatus, the outer plunger 81 is advanced first to fill the molten metal from the gate 30 side, and the inner plunger 82 is operated by a timer signal after a lapse of a set time of completion of the filling. Pressurization is performed by moving forward. Further, according to the present invention, a metal fitting that is fitted into the sleeve 41 toward the molten metal filled up to the runner 43 provided in the upper mold 22 and the inner hole 42 of the sleeve 41 is formed on the counter-gate-side end ring forming portion 17. By causing the pressure piston 44 to advance and pressurize, it is possible to particularly prevent the shrinkage cavities from being generated in the counter-ring-side end ring forming portion 17. In this case, it is natural that the pressure is increased by making the diameter of the piston in the hydraulic cylinder 45 to be pressurized larger than the diameter of the connected pressurizing piston 44. In addition, radial runner 43
As in the case of the sprue side, it is preferable to form so as to communicate with the cooling fin of the counter sprue side end ring forming part 17.

After the completion of the pressure molding, the upper mold 22 is opened, the lower mold 24 on which the middle mold 23 is placed is moved and cut at the solidified portion of the runner hole 29 in the same manner as in the above-mentioned conventional apparatus. Then, the motor rotor formed by casting is carried out from the middle mold 23. The runners 30, 43 are separated from the end ring after being carried out.

[0017]

According to the above-described die casting apparatus for a motor rotor according to the present invention, a mechanism for reducing the pressure in the mold cavity from the side of the sprue and the completion of the filling of the side of the sprue while utilizing the advantages of the conventionally known die casting. By providing the subsequent pressurizing mechanism, it is possible to prevent gas entrapment, poor run-off, and the occurrence of shrinkage cavities, particularly, on the counter-ring side end ring forming portion, so that product quality is stable and improved, and shrinkage cavities are improved. With a product without the above, the rotational balance adjustment is minimized and a motor rotor having stable rotational characteristics can be obtained, which has an effect of being a die casting device capable of exhibiting excellent productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a motor rotor die casting apparatus according to the present invention.

FIG. 2 is a sectional view showing a part of a state before the start of injection filling in the apparatus of FIG. 1;

FIG. 3 is a perspective view showing the structure of a general motor rotor.

FIG. 4 is a sectional view showing a main part of a conventional motor rotor die casting apparatus.

FIGS. 5A and 5B are cross-sectional views showing a motor rotor mold apparatus according to another conventional example, in which FIG. 5A shows a state before molten metal filling and FIG.

[Explanation of symbols]

 11, 61 Shaft 12, 62, 92 Iron core for core 14, 64, 94 Slot part 16, 96 End ring forming part (gate side) 17, 97 End ring forming part (counter gate side) 18 Cooling fin forming part 20, 70 Mold 22, 72 Upper mold 23, 73 Middle mold 24, 74, 95 Lower mold 25, 75 Mold cavity 26, 76 Fixed die plate 27, 77 Bolster 28, 78, 98 Injection sleeve 29, 79, 99 Gate hole 30, 80 Runner 31, 81 Outer plunger 32, 82 Inner plunger 33, 83, 93 Injection plunger 41 Sleeve 42 Inner hole 43 Runner 44 Pressurizing piston 45 Hydraulic cylinder 46 Piston rod 47 Groove 48 Cover 49 Vacuum device 50 stroke Sensor 51 Compression spring 52 Gate ring 60 Motor rotor 6 5 Conductor 66, 67 End ring 68 Cooling fin 71 Moving die plate 84 Hot water supply pipe 87, 88, 89 Compression spring

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H02K 15/02 H02K 15/02 J

Claims (1)

[Claims] 1. A mold clamping system comprising: a slot formed in an outer peripheral portion of a laminated core for a core mounted on a middle die; and an end ring molded portion formed in an upper die and a lower die with respect to the core for the core. The molten metal via a plurality of radial runners communicating from a gate provided in the lower die to a lower gate side end ring forming part by an injection plunger inserted into an injection sleeve connected to a hot water supply mechanism to the mold cavity to be supplied. A die casting apparatus for a motor rotor, which is formed by filling and pressurizing, wherein a plurality of radial runners communicating with a counter gate side end ring forming part provided on the upper mold, and one end communicating with the runner are provided at the other end. A sleeve that has an inner hole that opens outside the upper die and is fitted into the upper die, a pressurizing piston that is slidably inserted into the inner hole and connected to an actuator provided outside the upper die,
A plurality of grooves provided on the inner periphery on the other end side of the inner hole and opened to the outside, a cover for sealing the opening to the outside of the upper mold, and a vacuum device connected to the cover, Prior to the start of injection filling, the tip of the pressurizing piston is retracted to the position of the groove at the other end of the inner hole, and the vacuum device is operated to reduce the pressure in the mold cavity. The tip is advanced to the cutoff position of the groove, and the molten metal is injected and filled while maintaining the reduced pressure, thereby preventing gas entrainment and poor running around the molten metal. Die casting of a motor rotor, wherein the tip of the pressurizing piston is advanced and pushed into the molten metal that has reached the inner hole from a road, and pressurizes an end ring forming portion on a counter gate side to prevent shrinkage cavities. apparatus.