JPH027856A - Manufacturing device for rotor of rotary electric machine - Google Patents

Abstract

PURPOSE:To omit work for removing burr after molding and prevent the efficiency of work from being lowered, by opening a pin point gate at a projecting section inside a cavity. CONSTITUTION:A fused mixture is injected in a cavity 18, and a previously set rotary shaft 40 is fixed in a state that the shaft 40 is inserted through the central section of a cylindrical resin magnet 52 molded in the cavity 18, and a rotor for a rotary electric machine is obtained. In this case, the resin magnet remains at a pin point gate 30, and so when the mold of the rotor is removed from the cavity 18, then burr 15 remains on the end surface of the rotor. However, a metallic mold 20 is provided with a projecting section 28 projected inside the cavity 18, and so on the end surface of the rotor, a recessed section 39 is molded at the same time. The burr 15 is to be projected to the recessed section 39, and burr removing work for removing the burr is not needed in particular, and there is no problem even if the burr is left as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is applicable to the production of a rotor for a rotating electric machine in which a rotating shaft is integrally attached to an anisotropic cylindrical magnet, after the rotor is removed from a mold. The present invention relates to an apparatus for manufacturing a rotor for a rotating electrical machine that can eliminate the need for complicated deburring operations.

2. Description of the Related Art A rotor for a rotating electric machine, for example, a rotor used in a bicycle generator, in which a rotating shaft is inserted and fixed to a cylindrical magnet, has been conventionally manufactured through the steps described below. That is, a small amount of binder is added to isotropic ferrite ferromagnetic powder such as Ba ferrite magnet powder or Sr ferrite magnet powder, and the mixture is press-molded at a pressure of about 1 to 2 t/ad to form a through hole in the center. A cylindrical molded body is obtained. This molded body is sintered at a high temperature of 1150 DEG C. to 1250 DEG C., and the outer periphery is polished by centerless processing to produce a mouthpiece body 1o (FIG. 1). Next, the one-rotation shaft 12 is inserted into the center through hole 14 of the rotor body 10, and as shown in FIG. Nt! , the magnet rotor is completed by multi-pole magnetization so that the south poles alternate. FIG. 3 shows an outline of this series of manufacturing steps.

The method of manufacturing a rotor for a rotating electric machine according to the prior art described above requires a large number of steps, and the rotor rotating shaft obtained by the method has a drawback that the centering accuracy is low and center runout is likely to occur. this is.

Due to the heat effect during sintering after press forming, through hole 1
This is due to the fact that the inner diameter of 4 varies, but at present it is not possible to polish the inner diameter due to cost constraints. Also 1
Isotropic ferrite magnet powder is magnetized after sintering as described above, but the arrangement of the powder particles is already fixed, so
It is not possible to increase the degree of orientation by aligning the axis of easy magnetization of the particles with the magnetization direction, and therefore there is a limit to the improvement of magnetic properties.

Therefore, as disclosed in Japanese Patent Publication No. 47-35721,
A manufacturing method in which a molten mixture of ferromagnetic powder and synthetic resin is injected into a cavity while applying a multi-pole magnetic field, and the mixture is cooled and solidified to form an anisotropic magnet.''
The following method of manufacturing a rotor for a rotating electric machine is based on the technology disclosed in Japanese Patent No. 5-8857, "A manufacturing method of molding a magnet by aligning the rotor rotating shaft meticulously in a cavity so as to face it." Suggested. That is, the axis of rotation of the rotor is aligned in the cylindrical cavity of the mold, and the rotor rotation axis is exposed, and the ferromagnetic powder and the synthetic resin are applied while applying a magnetic field of multiple equally divided poles from the outside in the radial direction of the cylindrical cavity. By injecting a molten mixture of and into the cavity, and then cooling and solidifying the mixture, a rotor for a rotating electrical machine made of a cylindrical anisotropic magnet into which a rotating shaft is inserted and fixed is obtained. According to this method, a rotor for a rotating electric machine is manufactured that improves the centering accuracy of the rotating shaft, eliminates center runout, and significantly improves magnetic properties.

Problem to be Solved by the Invention The mold used in the magnetic field injection molding is equipped with a sprue and a gate communicating with the sprue as an introduction path for injecting the molten mixture into the cavity.
A so-called pinpoint gate whose diameter is extremely small is used. However, with this pinpoint gate, the molten mixture remains solidified in the gate at the end of injection, so when the rotor is removed from the cavity, as shown in FIG.
The solidified particles 15 of the resin magnet remain as traces and protrude from the open end of the rotor 1o.

For this reason, after the rotor molding, the complicated work of separately performing deburring is required, which is a major factor in reducing work efficiency.

OBJECTS OF THE INVENTION The present invention was devised to suitably solve the above-mentioned drawbacks inherent in rotor manufacturing apparatuses for rotating electric machines, and includes manufacturing a rotor in which a rotating shaft is inserted through a cylindrical magnet. It is an object of the present invention to provide an apparatus for manufacturing a rotor for a rotating electric machine, which eliminates the need to remove particles from a rotor after injection molding.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, the present invention comprises a mold made of a non-magnetic material defining one cylindrical cavity, connected to a magnetizing coil, and A multi-pole magnetized yoke made of a ferromagnetic material facing the radial outer periphery of the cylindrical cavity at equal central angles, a through hole for inserting the rotor rotating shaft formed in the center of the bottom of the cylindrical cavity, and a through hole in the through hole. A knockout pin that can be raised and lowered to protrude from a through hole drilled adjacent to it, a mold made of a non-magnetic material that can freely open and close the opening of the cylindrical cavity, and a mold made of a non-magnetic material that can be opened and closed. In an apparatus for manufacturing a rotor for a rotating electric machine, the non-magnetic mold for freely opening and closing the opening of the cylindrical cavity is provided with a protrusion protruding inward of the cavity. and the pinpoint gate is configured to open in this raised portion.

Embodiment Next, a preferred embodiment of the apparatus for manufacturing a rotor for a rotating electrical machine according to the present invention will be described below with reference to the accompanying drawings. First, in one embodiment of the rotor manufacturing apparatus for a rotating electrical machine shown in FIG. 5, reference numeral 18 indicates a cylindrical cavity formed in a mold, and this cavity 18 is connected to a fixed side mold 20 made of a non-magnetic material. The bottom portion 22 and a cylindrical inner circumferential wall surface are defined by this. Further, as shown in FIG. 6, magnetizing yokes 24 made of a ferromagnetic material having multiple poles at equal central angles are arranged on the radial outer circumference of the cavity 18, and the tip of each magnetizing yoke 24 is located inside the cavity 18. It faces directly to form a part of the inner circumferential wall surface of the cavity 18.

The magnetizing yoke 24 is composed of an even number of four or more poles,
S@ and Ni2 are arranged alternately at a predetermined central angle, and the present embodiment has a four-pole structure. Further, the magnetizing yoke 24 is connected to a magnetizing coil (not shown), and by exciting the magnetizing coil, a strong magnetic field is applied within the cylindrical cavity 18.

A movable mold 26 made of a non-magnetic material is disposed above the opening of the cylindrical cavity 18 so as to be movable up and down, and which can open and close the opening. A truncated conical protuberance 28 that slightly protrudes inward of the cavity is integrally formed in the portion of the movable mold 26 facing the opening of the cavity 18. A pinpoint gate 30 for use is vertically drilled. Furthermore, another movable mold 32 made of a non-magnetic material is disposed above the movable mold 26 so as to be movable up and down, and at the interface between the top of the movable mold 26 and the movable mold 32.

As shown in the figure, a runner 34 is formed, and this runner 34 is connected to a sprue 36 and a nozzle port 38 formed in the movable mold 32. In addition, each mold 20, 2
As the non-magnetic material constituting 6 and 32, for example, austenitic stainless steel is preferably used.

Further, the fixed mold 20 forming the bottom 22 of the cylindrical cavity 18 has a through hole 42 vertically bored in the center of the bottom for inserting the rotor rotation shaft 40, as will be described later. In this case, the inner diameter of the through hole 42 is set in advance so that an annular gap of about 2/100 to 3/100 of the outer diameter of the rotating shaft 40 is formed, and furthermore, from approximately the middle of the through hole 42 A large-diameter stepped hole 44 is integrally formed at the bottom. This is to reduce the frictional resistance caused by the one-rotation shaft 40 coming into contact with the inner wall of the through hole 42 when the rotor is demolded after injection molding.

Further, a plurality of through holes 46 are bored adjacent to the center through hole 42 (FIG. 5), and a knockout pin 48 is inserted through the through holes 46 so as to be able to move up and down.
It is possible to protrude inside.

Note that it is preferable that a contact plate 50 is removably positioned at the external open end of the center through hole 42, and that the position of the rotating shaft 40 in the cavity is regulated by the contact plate 50.

Effects of the Embodiment The actual use of the manufacturing apparatus according to the embodiment configured as described above will now be explained first. First, as shown in FIG. 5, the rotating shaft 40 is inserted into the through hole 42 bored at the bottom of the cylindrical cavity 18, and the axis of the rotating shaft 40 is aligned with the cavity
Align it with the axis of 8. In this case, by closing the lower opening of the center through hole 42 with the contact plate 5o, the end of the one-rotation shaft 40 comes into contact with the contact plate 50 and is regulated in a predetermined position, so that the rotation shaft 4o always has a predetermined size. It is set so that it faces into the cavity 18 by the length.

Next, a mixture consisting of a ferromagnetic powder with a large magnetic anisotropy constant and a synthetic resin is heated and melted, and this molten mixture is injected from the nozzle port 38 of the movable mold 32 and the sprue 34
and inject into the cylindrical cavity 18 through the pinpoint gate 30.

Also, in synchronization with this, a magnetizing coil (not shown) is excited,
A strong magnetic field is applied to the cavity 18 from the outside in the radial direction via the magnetizing yoke 24. In this way, by applying a multi-pole magnetic field while the mixture of magnet powder and synthetic resin is in a molten state and the five-particle arrangement is not solidified, it is possible to orient the axis of easy magnetization of the magnet powder particles in the radial direction. A cylindrical anisotropic magnet with excellent magnetic properties is placed in cavity 1.
It is molded into 8. FIG. 8 schematically shows a state in which the easy axis of magnetization of the particles of this cylindrical anisotropic magnet is oriented in the magnetization direction.

Examples of the ferromagnetic powder with a large magnetic anisotropy constant used in the examples include Ba ferrite magnet powder, Sr ferrite magnet powder, or rare earth magnet powder (RCos type or R2O, 17 type, where R is a rare earth element. ), the locally anisotropic manganese aluminum (Mn-A
I-C) Magnet powder etc. are preferably used. Note that it is desirable that the particle diameter of these ferromagnetic powders be around the single magnetic domain particle diameter.

Synthetic resins are used as organic binders, such as thermoplastics, polyethylene, nylon.

Polypropylene and polyphenyl cyphide can be used, and as the thermosetting resin, phenol, epoxy, etc. can be used. Further, a desirable blending ratio of the ferromagnetic powder and the synthetic resin is about 50 to 65% in volume fraction of the magnet powder. Furthermore, the molding temperature of the molten mixture during injection molding is 150 to 35
The temperature range is preferably 0°C, and the applied magnetic field is 3000°C.
It is necessary to set it to 0s or more.

In this way, the molten mixture is injected into the cavity 18, magnetized, and then cooled and solidified.
The rotating shaft 40, which was set in advance so as to face inside the cavity 18, is inserted into the center of the cylindrical resin magnet 52 molded in the cavity 18 and is integrally fixed therein. A rotor for use is obtained. In this case, since the solidified resin magnet remains in the pinpoint gate 30 at the end of injection, when the rotor is demolded from the cavity 18, the particles 15 remain protrudingly on the end face of the rotor. Become. However, as mentioned above, since the mold 20 is provided with a protrusion 28 that protrudes inward from the cavity 18, the one end surface of the molded rotor has a portion corresponding to the protrusion 28. A recess 39 is formed at the same time. Since the burr 15 protrudes into the center of the recessed portion 39, there is no need to perform a burr removing operation to remove it, and there is no problem in leaving it as is. In this embodiment, a rotor for a bicycle generator has been described, but the present invention can be widely and suitably used in manufacturing magnet rotors of general rotating electric machines, such as rotors of other surface current motors.

Effects of the Invention As explained above, according to the apparatus for manufacturing a rotor for a rotating electric machine according to the present invention, a non-magnetic mold that can open and close the opening of a cylindrical cavity is provided with a mold that is directed inward of the cavity. has a protruding ridge.

The configuration is such that a pinpoint gate is opened in this raised portion. Therefore, on one end surface of the rotor obtained by injection molding in a magnetic field, a recess corresponding to the protrusion is simultaneously molded. Furthermore, since the resin magnet remaining and solidified in the pinpoint gate only protrudes as a lump at the center of this recess, there is no problem in leaving it alone. Therefore, beneficial effects such as no need for complicated deburring work and no fear of lowering the required quality standards can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing how a rotating shaft is attached to a rotor for a rotating electric machine according to the prior art, Fig. 2 is a longitudinal cross-sectional view of the rotor according to the prior art, and Fig. 3 is a manufacturing procedure for a rotor according to the prior art. 4 is a longitudinal cross-sectional view showing a rotor for a rotating electric machine manufactured by magnetic field injection molding, with pars remaining prominently at the open end thereof; FIG. 6 is a cross-sectional view taken along the line A-A in FIG. 5, FIG. 7 is a vertical cross-sectional view of a rotor for a rotating electrical machine manufactured according to the present invention, and FIG. 8 is a vertical sectional view of a manufacturing apparatus according to an embodiment. 8 is an explanatory diagram showing the particle orientation of the cylindrical magnet shown in FIG. 7. FIG. 18... Cylindrical cavity 20... Fixed side mold 24... Magnetizing yoke 26
...Movable side mold 28...Protuberance 30...Pinpoint gate 40...Rotor rotation shaft 42...Through hole 48...
・Output bin FIG, 1 FIG, 4 ] 4 5 FrG, 3 FIG, 2 FIG, 7 FIG, 8 (No rear drawing)

Claims (1)

[Claims] A mold (20) made of a non-magnetic material that defines a cylindrical cavity (18), and a mold (20) connected to a magnetizing coil and having an equicentral angle on the radial outer circumference of the cylindrical cavity (18). A multi-pole magnetized yoke (24) made of a ferromagnetic material facing the cylindrical cavity (18), a through hole (42) for inserting the rotor rotating shaft bored in the center of the bottom of the cylindrical cavity (18), and the through hole (42) A knockout pin (48) that can be raised and lowered to protrude from a through hole (46) bored adjacent to the cylindrical cavity (18).
A mold made of a non-magnetic material that can open and close the opening of the
26) and a pinpoint gate (30) formed in the openable and closable non-magnetic mold (26), wherein the cylindrical cavity (1
8) A non-magnetic mold (20
) is provided with a protrusion (28) projecting inward of the cavity (18), and the pinpoint gate (30) is configured to open in the protrusion (28). Manufacturing equipment for electrical rotors.