JP2002369471A - Metal mold for molding motor rotor and die cast molding method of motor rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the injection speed of melt into each penetrating hole, prevent generation of blowholes, improve quality of a motor rotor, simplify the treatment method of a biscuit part and improve productivity. SOLUTION: A drag 22a arranged in the lower part of a rotor core laminate has a cavity 3 for forming a lower end ring and a plurality of wells 30N, 30R for injecting the melt. The well 30N has an almost trapezoidal form, and the well 30R has a form where the top and bottom of the well 30N are inverted. A virtual line DD, connecting an end point a of the well 30N with a circle center O of a cavity 3', is assumed, with a short point b of the well 30R being set on the virtual line DD, or on the well 30N side more adjacent than the line DD.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor rotor molding die for molding a motor rotor and a method for die-casting the motor rotor, and more particularly to a motor rotor molding die and a motor rotor suitable for a vertical injection type molding machine. The present invention relates to a die casting method.

[0002]

2. Description of the Related Art Conventionally, a motor rotor such as a three-phase induction motor has a thin silicon steel plate 1 'as shown in FIG.
Are laminated to form a rotor core laminated body 1, and the rotor core laminated body 1 is manufactured by, for example, die-casting an aluminum alloy or the like and integrating them. Each of the silicon steel plates 1 ′, 1 ′,...
Are formed, and when the silicon steel plates 1 ′, 1 ′,... Are laminated, the through holes h are arranged in a straight line. A slot for forming a conductor is formed. The rotor core laminate 1 is set in a die casting machine (not shown), and through holes h1 and h
By injecting a molten metal for forming a conductor such as an aluminum alloy from 2, h3,..., Conductors C1, C
2, a large number of C3 are formed. Further, the die casting machine is provided with mold cavities 3, 3 'for forming end rings for short-circuiting the conductors C1, C2, C3,... By being injected, the upper end ring 4 and the lower end ring 4 ′
Is formed.

[0003] Motors have various uses,
The most suitable die casting method according to each application is adopted. In recent years, high-speed rotation of motors has been progressing, and accordingly, the quality required for high-speed motors has become strict. For example, when a motor having a rotation speed of 10,000 rpm is manufactured, the motor rotor used for the motor must have sufficient strength to withstand the large centrifugal force. For this reason, it is necessary to form a high-strength motor rotor having a dense metal structure without air entrapment. As a method of die casting, a so-called horizontal injection method and a vertical injection method are known. For manufacturing a motor rotor having a dense metal structure for a high-speed motor, a vertical injection method is used. Was. That is, as shown in FIG.
Are arranged so that the through-holes h face in the vertical direction, and the molten metal is injected and filled through the vertical holes 5 as runners provided on the hole side below the through-holes h. Then, the molten metal first goes to the lower end ring 4 '
Is formed in the lower cavity 3 ′ where the end ring 4 is formed, and then passes through the through hole h and finally fills the upper cavity 3 where the end ring 4 is formed.

[0004]

However, according to the vertical injection type die casting molding machine shown in FIG. 8, a slot formed by a through hole (for example, hc in FIG. 8) located near the vertical hole 5, There is a large difference in the time required for the molten metal to reach the upper cavity 3 with the slot formed by the through hole (for example, hf in FIG. 8) located far from the vertical hole 5. Therefore, for example, the molten metal flows downward from the slot of the through hole hc through the upper cavity 3 from above the slot of the through hole hf, and as a result, the gas is confined in the slot of the through hole hf. Will be done. In this way, a cavity is formed in the through-hole located far from the vertical hole 5, and this causes a reduction in the strength of the motor rotor.

[0005] Further, while the slots are thin rod-shaped, the cavities 3, 3 'in which the end rings 4, 4' are formed are flat, so that the molten metal in the slots solidifies first, and the end ring portion is removed. After this, it solidifies. For this reason,
There is a problem that the pressurizing force for the riser does not sufficiently act on the end ring portion, so that a shrinkage cavity is easily generated in the end ring 4 of the upper mold.

After the rotor core laminate 1 is die-cast, the molten metal solid (biscuit) is left in the vertical hole 5 in a connected state. This biscuit portion must be cut off by another device such as a trimming press, which causes a problem that the manufacturing cost is increased, the manufacturing time is lengthened, and the production efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has the advantage of making the injection speed of molten metal into each through hole uniform, thereby preventing the occurrence of shrinkage cavities, improving the quality of the motor rotor, and improving the biscuit portion. Processing method,
An object of the present invention is to provide a motor rotor molding die excellent in productivity and a method for die-casting a motor rotor.

[0008]

SUMMARY OF THE INVENTION A motor rotor molding die according to the present invention is a metal mold for a rotor core laminate in which a plurality of steel plates are laminated and a plurality of through holes extending in the laminating direction are formed in the steel plates. A vertical injection motor rotor molding die for integrating the rotor laminated body by disposing a molten metal into the mold cavity and into the through hole and die-casting the molten metal into the mold cavity and the through hole; An upper mold disposed on an upper part of the body, a lower mold disposed on a lower part of the rotor core laminate, and a part formed on a portion of the upper mold in contact with the rotor laminate, and by pouring the molten metal. An annular first groove for forming an upper end ring of the motor rotor, and a portion formed in contact with the rotor laminated body of the lower mold, and formed by injecting the molten metal. An annular second groove for forming a lower end ring of the motor rotor; and a second groove penetrating the lower mold and reaching the second groove. And a plurality of pits for advancing to the first groove, wherein the plurality of pits are arranged so as to draw a ring (R) along the arrangement of the through holes, and are adjacent to each other. The adjacent contour lines (Fa, Fb) of the adjacent portions of the pit are substantially parallel to each other, and the direction of the adjacent contour lines (Fa, Fb) intersects the diameter direction of the ring (R). And the contour line (L
In) is a virtual line (D) connecting a point (a) at an acute angle with one of the adjacent contour lines (Fa) and the center point (O) of the ring.
Assuming D), the contour line (Lo
The point (b) where the outgoing line (ut) intersects the other of the adjacent contour lines (Fb) at an acute angle is on the virtual line (DD) or the virtual line (D
It is characterized in that it is present on the other side of the vertical hole than in D).

According to the present invention, the molten metal is sufficiently injected also into the through holes existing between the adjacent vertical holes, so that the injection amount and the injection speed of the molten metal into each through hole are made uniform. As a result, a motor rotor having a dense metal structure can be obtained, and a high-speed motor can be supported.

In the present invention, the lower mold is composed of a first lower mold and a second lower mold divided into upper and lower parts, and the vertical hole is formed by the first lower mold and the second lower mold. Is preferably formed to penetrate vertically.

[0011] The first lower mold and the second lower mold are divided by a plane, and after the molten metal is solidified, a load is applied to the second lower mold in a lateral direction so that the two are separated. It is preferable to configure so that it can be divided in the horizontal direction. By doing so, the molten metal solidified material can be efficiently treated without using a separate instrument, and the lower mold can be easily reused, and the production cost can be reduced. In addition, the vertical hole is formed between the upper surface of the first lower mold and the flat surface in a tapered shape expanding upward, and the lower surface of the flat surface and the lower surface of the second lower mold is It is preferable to form a tapered shape extending downward between them.

[0012] A method for die-casting a motor rotor according to a second invention of the present application is to mold a rotor core laminate in which a plurality of steel plates are laminated and a plurality of through holes extending in the laminating direction are formed in the steel plates. In a motor rotor die-casting method in which a molten metal is injected into the mold cavity and die-casting is performed, a pair of upper and lower first and second lower dies are disposed below the rotor core laminate. And a step of injecting the molten metal into the rotor core laminate through a plurality of pits vertically penetrating the first lower mold and the second lower mold, and after the molten metal is solidified, A step of applying a shear stress between the first lower mold and the second lower mold to separate the first lower mold and the second lower mold.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a structure of a motor rotor molding die according to a first embodiment of the present invention, and shows an arrangement relationship between the die and a rotor core laminate 1 to be die-cast molded. As shown in FIG. 1, a motor rotor molding die according to the present embodiment includes an upper die 21 disposed above the rotor core laminate 1 and a lower die 22 disposed below the rotor core laminate 1. And the middle dies 23L and 23R arranged on the left and right sides of the rotor core laminate 1 and the center dies 24L formed in the center of the rotor core laminate 1 and inserted into the recesses 22V of the lower mold 22. And a caulking jig 24 adapted to be used. FIG. 1 shows only the shape of the surface in contact with the rotor core laminate 1 for the middle dies 23L and 23R.

As will be described later, the upper mold 21 can be moved up and down by a vertical movement mechanism 40 not shown in FIG. Further, the upper mold 21 is provided with a cavity 3 for forming an upper end ring of the motor rotor, and molten metal is injected into the cavity 3 through a number of slots S provided in the rotor core laminate 1. Thus, the upper end ring 4 as shown in FIG. 8 is formed. The lower mold 22 has a caulking jig 24 on its upper surface.
The diameter D6 is slightly larger than the diameter of the caulking jig 16 in order to prevent interference with the caulking jig 16. Further, the diameter D6 needs to be determined in consideration of the pitch circle (PCD) D5 of the balancer forming section 15 described later and the size of the balancer.

The middle mold 23L is fixedly arranged on a mounting table. On the other hand, the middle mold 23R is movable relative to the middle mold 23L by an opening / closing mechanism (not shown). When setting the laminate 1, the middle mold 23R is moved rightward. The middle mold 23
L, 23R are provided with concave portions 23LV, 23RV formed according to the shape of the lower mold 22 described above.

The lower mold 22 further includes a first lower mold 2.
2a and a second lower mold 2 disposed below the first lower mold
2b. The lower surface of the first lower die 22a is flat, and the upper surface of the second lower die 22 is also flat, so that the first lower die 22a and the second lower die 22b have a gap therebetween. It is arranged in close contact without holding. Further, a cavity 3 'for forming a lower end ring of the motor rotor is provided on the upper surface of the first lower mold 22a. The cavities 3, 3 'are connected to the slots S. In FIG. 1, reference numeral 15 denotes a balancer forming part for forming a balancer for improving the rotation stability of the motor rotor.

Further, from the bottom surface of the second lower mold 22b to the upper surface of the first lower mold 22a,
', A vertical hole 30 for injecting into the slot S and the cavity 3 is formed. FIG. 2 shows the first lower mold 22a viewed from the direction of the upper mold 21. The pit 30 is shown in FIG.
As shown in the figure, a plurality of rings are arranged at regular intervals L on the ring along the cavity 3 'formed in a ring. As shown in FIG. 2, each of the vertical holes 30 has a trapezoid-like shape (hereinafter referred to as a substantially trapezoidal shape) in which the upper and lower sides of the trapezoid are formed in an arc (hereinafter, referred to as a substantially trapezoidal shape). Are alternately arranged with vertical holes 30 </ b> R having a shape (hereinafter, referred to as a substantially inverted trapezoidal shape) which is inverted in the vertical direction. In the present embodiment, each of the pits 30N, 30R,
30N, 30R... Have their lower sides aligned with the circumference Lin centered on the center point O of the cavity 3 ', and their upper sides aligned with the circumference Lout centered on the point O. However, as long as the injection speed of the molten metal into the slot S is made uniform, a slight deviation may be caused. Hereinafter, the circumference Lin is referred to as an inner contour line, and the Lout is referred to as an outer contour line.

Each of the 30N, 30R adjacent to each other
Of adjacent part of (hereinafter referred to as adjacent contour)
Fa and Fb are substantially parallel to each other. Furthermore, the directions of the contour lines Fa and Fb intersect with the diametrical direction of the ring in which the cavity 3 'exists. Further, in the present embodiment, a point of intersection between the inner contour line Lin and the adjacent contour line Fa is represented by a, an intersection of the outer contour line Lout and the adjacent contour line is represented by b, and a virtual line connecting the point O and the point a is represented by DD. In this case, the point b is located on the virtual line DD or on the side of the vertical hole 30N adjacent to the virtual line DD. However, if the point b is too close to the pit 30N,
Since the interval L becomes narrow and a durability problem as described later occurs, a position that does not cause such a problem is selected.

As described above, since the first lower mold 22a is provided with the balancer forming portion 15 for forming a balancer, the balancer forming portion 15 and the vertical hole 30 are formed.
Is selected such that it can withstand the injection pressure from a melt injection mechanism (not shown).

FIG. 3 shows a positional relationship between the slot S and the vertical hole 30 when the vertical hole 30 is arranged under the above conditions. In FIG. 3, six slots S are included in the hole shape of one vertical hole 30. This number is
The number is preferably set in consideration of the uniformity of the flow of the molten metal, the labor required for processing the lower mold 22, and the like. As shown in FIG. 3, when the diameter of the outer peripheral contour line (Lout) of the vertical hole 30 is D1 and the diameter of the inner peripheral contour line (Lin) is D2, the diameter D3 of the outer peripheral contour line of the slot S is equal to D1. Preferably, or slightly smaller. When the slot S is formed near the outer periphery of the silicon steel plate, it is preferable that D1 be approximately equal to the diameter of the silicon steel plate.

Next, a procedure for die-casting the motor rotor using the motor rotor molding die of the present embodiment will be described with reference to FIGS. FIG. 4A shows the appearance of a vertical injection type die casting mold 100 employing the motor rotor molding die of the present embodiment, in which the rotor core laminate 1 to be die cast is set. This shows the previous state. In this state, the upper mold 21 is retracted upward by the vertical movement mechanism 40, and the middle mold 23R is retracted rightward.
The rotor core laminate 1 can be set.

Next, as shown in FIG.
After the rotor core laminate 1 is placed on the lower mold 2 and the rotor core laminate 1 is fixed on the lower mold 22 by the caulking jig 24,
This rotor core laminated body 1 is die-cast
Set inside. At this time, the lower mold 22 is fitted into the recess 23LV of the middle mold 23L.

Next, the upper die 21 is lowered by the vertical movement mechanism 40 to make contact with the upper part of the rotor core laminate 1 (FIG. 4C). Thereafter, the middle mold 23R is moved leftward to complete the entire mold clamping. Next, the molten metal MM is injected into the cavity 4 ′, the slot S, and the cavity 4 through the vertical hole 30 by a molten metal injection mechanism (not shown) (FIG. 5).
(A)). Since the shape of the vertical hole 30 is as described above, the molten metal is uniformly injected into each slot S, so that a motor rotor having a dense metal structure can be obtained.

When the molten metal has solidified, the middle mold 23R is retracted rightward (FIG. 5B), and the formed rotor core laminate 1 is taken out together with the caulking jig 16 and the lower mold 22 (FIG. 5 (B)). c))

The rotor core laminate 1 taken out is shown in FIG.
As shown in (a), the molten metal solidified in the vertical hole 30 is in a state of being connected to the lower mold 22.
Here, a lateral force (in the direction of the arrow in FIG. 6B) is applied to the side of the second lower mold 22b by a hammer or the like. This force acts as a shearing stress on the solidified molten material (biscuit) formed in the portion of the vertical hole 30, whereby the solidified molten material is cut at the plane P22. At this time, between the upper surface of the first lower mold 22a and the plane P22,
As shown in FIG. 2, the shape of the vertical hole 30 is preferably formed in a tapered shape in which the cross-sectional area increases as it goes upward. Further, between the flat surface 22 and the lower surface of the second lower mold 22b, the shape of the vertical hole 30 is formed in a tapered shape in which the cross-sectional area increases downward as shown in FIG. preferable. Thereby, the solidified molten material can be more easily released.

Thereafter, the second lower mold 22b is separated from the first lower mold (FIG. 6C). Then, while separating the first lower mold 22a from the rotor core laminate 1 and hitting the upper portion of the vertical hole 3 of the second lower mold 22b with a hammer or the like, the molten metal solidified product 50 and the second lower mold 22a are hit. Is separated. The lower molds 22a and 22b thus separated are cleaned, purified,
By applying the release agent, it can be reused in the next molding. It is preferable to prepare a plurality of lower dies for efficient production.

As described above, according to the present embodiment, the processing of the biscuit portion can be easily executed without using a separate device such as a trimming press, so that production efficiency can be improved. .

[Second Embodiment] In the above-described first embodiment, the vertical holes 3 have a shape in which a substantially trapezoidal shape and a substantially inverted trapezoidal shape are alternately arranged. However, the present invention is not limited to this. However, for example, as shown in FIG. 7, a shape similar to a parallelogram in which the upper side and the lower side of the parallelogram are formed in an arc shape may be used. In addition, various changes, modifications, improvements, and the like can be made without departing from the spirit of the present invention, and it goes without saying that all of them are included in the scope of the present invention.

[0029]

As described above, according to the rotor motor forming die according to the present invention, the injection speed of the molten metal into each through hole is made uniform, the air is prevented from being entrained, and the occurrence of nests is thereby prevented. It is possible to prevent such a situation and improve the quality of the motor rotor. Further, according to the second aspect of the present invention, the processing method of the biscuit portion is simplified, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a motor rotor molding die according to the present invention.

FIG. 2 is a view showing a structure of a lower mold 22 as a component of a motor rotor molding mold according to the present invention.

FIG. 3 is a view for explaining a positional relationship between a vertical hole 30 and a slot S of the rotor core laminated body 1;

FIG. 4 is a view for explaining a method of forming a motor rotor by a die casting forming machine using a motor rotor forming die according to the present invention.

FIG. 5 is a view for explaining a method of forming a motor rotor by a die casting forming machine using a motor rotor forming die according to the present invention.

FIG. 6 is a diagram for explaining a method of forming a motor rotor by a die casting forming machine using a motor rotor forming die according to the present invention.

FIG. 7 shows another embodiment of the motor rotor molding die according to the present invention.

FIG. 8 is an explanatory view showing a structure of a general motor rotor.

[Description of Signs] 1 ... Rotor core laminate 1 '... Silicon steel plate 3, 3' ... Cavity 4, 4 '... End ring 5 ... Vertical hole h... Through hole c... Conductor S... Slot 15. Upper mold 22 Lower mold 22a First lower mold 22b Second lower mold 23L, 23R Middle mold 24・ ・ ・ ・ ・ ・ Caulking jig 30 ・ ・ ・ ・ ・ ・ Pit

Continuation of the front page F term (reference) 5H013 MM01 5H615 AA01 BB01 BB06 BB14 PP03 PP06 PP13 PP14 SS12 SS13

Claims (5)

[Claims] 1. A rotor core laminate having a plurality of steel plates laminated and having a plurality of through holes extending in the lamination direction formed in the steel plates is disposed in a mold cavity, and the rotor core laminate is disposed in the mold cavity and the through-hole. In a motor rotor molding die for vertical injection for integrating the rotor laminated body by injecting a molten metal into a hole and performing die casting, an upper mold disposed above the rotor core laminated body; A lower mold disposed at a lower part of the body; and an annular second mold formed at a portion of the upper mold in contact with the rotor laminated body and forming an upper end ring of the motor rotor by injecting the molten metal. A groove formed in a portion of the lower mold that is in contact with the rotor laminate, and configured to form a lower end ring of the motor rotor by injecting the molten metal. And a plurality of grooves for penetrating the lower mold and reaching the second groove, and for allowing the injected molten metal to proceed to the second groove, the through hole, and the first groove. And the plurality of pits are annular (R) along the arrangement of the through holes.
The adjacent contour lines (Fa, Fb) of the adjacent portions of the adjacent vertical holes are substantially parallel to each other, and the direction of the adjacent contour lines (Fa, Fb) is (R) is a direction intersecting with the diametric direction, and a point (a) at which the contour (Lin) of the inner peripheral portion of the vertical hole intersects one of the adjacent contours (Fa) at an acute angle and the point of the ring Assuming an imaginary line (DD) connecting the center point (O), a point (b) at which the contour (Lout) of the outer peripheral portion of the pit intersects the other (Fb) of the adjacent contour at an acute angle is: A motor rotor molding die, which is provided on the virtual line (DD) or on the side of the other vertical hole adjacent to the virtual line (DD). 2. The lower mold comprises a first lower mold and a second lower mold which are divided into upper and lower parts, and the vertical hole vertically connects the first lower mold and the second lower mold. The mold for molding a motor rotor according to claim 1, wherein the mold is formed so as to penetrate through. 3. The first lower mold and the second lower mold are divided by a plane, and after the molten metal is solidified, a load is applied to the second lower mold in a lateral direction. The mold for molding a motor rotor according to claim 2, wherein the two can be separated in a lateral direction. 4. The vertical hole is formed between the upper surface of the first lower mold and the flat surface in a tapered shape expanding upward, and the vertical hole and the second lower die are formed. 4. The motor rotor molding die according to claim 2, wherein the mold is formed in a tapered shape extending downward from the lower surface of the motor rotor. 5. 5. A rotor core laminate in which a plurality of steel sheets are laminated and a plurality of through holes extending in the laminating direction are formed in the steel sheets, and the rotor core laminate is disposed in a mold cavity. In a die casting method for a motor rotor to be injected and die cast, a step of disposing a pair of upper and lower first lower dies and a second lower die below the rotor core laminate, A step of injecting the molten metal into the rotor core laminate through a plurality of vertical holes penetrating the lower mold in the vertical direction, and after the molten metal is solidified, between the first lower mold and the second lower mold. Separating the first lower mold and the second lower mold by applying shear stress to the die.