JPH057938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to the production of shaft-integrated resin magnet rotors such as permanent magnet rotor type synchronous motors with outputs ranging from several watts to several tens of watts for use as drive sources for household appliances. It is about the method.

BACKGROUND ART An example of a conventional permanent magnet rotor type synchronous motor of this type is one having a structure shown in FIG. As shown in the figure, this permanent magnet rotor type synchronous motor has a drive coil 3 inserted into a magnetic path piece 2 of a stator core having a substantially U-shape, and placed between magnetic pole parts 6a and 6b of the stator core 1. A permanent magnet rotor 4 having a shaft 5 is rotatably supported by a bearing body 7.

This synchronous motor has a simple structure, is compact, and can obtain a relatively large output, and is used as a drive source for household appliances such as small orange squeezers. As the permanent magnet rotor 4, a resin magnet rotor is used, which is cheaper and easier to mass produce than a sintered product.

This resin magnet rotor is made of a mixture of synthetic resin and ferromagnetic powder such as ferrite, and naturally the magnetic flux density is inferior to that of a sintered product, so it is necessary to increase the volume and the diameter also increases. This leads to an increase in air gaps in magnetic field orientation molding and requires a large magnetic field strength. However, in order to achieve sufficient orientation molding, the rotor was formed into a half-shape so that it could fit into the gap that was possible with the conventional technology, magnetic field orientation molding was performed, and the half-shape 4a and 4b were bonded together with the shaft 5. A permanent magnet rotor 4 was formed.

Problems to be Solved by the Invention However, this bonding method is not satisfactory in terms of productivity and economy, and there are many methods for integrally molding the shaft by making full use of the merits of injection molding. I have been doing experimental research.

The magnetic properties of a resin magnet are proportional to the amount of ferromagnetic powder mixed, and when a mixture containing a large amount of ferromagnetic powder is melted, the viscosity increases and the fluidity decreases. When molding resin magnets, it is necessary to apply a magnetic field in a heated state during molding and align the ferromagnetic powder particles with the direction of the magnetic field application and the axis of easy magnetization.The molding method for resin magnets is the usual resin injection method. Compared to molding methods, there are many difficulties such as fluidity and magnetic field application.

Moreover, integral injection molding with a shaft is technically more difficult than conventional injection molding with a half-split shape. For example, the injection quantity is twice as large as that of the half-split shape, the magnetic field gap is doubled and a strong magnetic field is required to be applied, and the shaft diameter, which can be set arbitrarily in the bonding method, is affected by the injection pressure. The diameter has to be increased until it can endure, which affects the flow of the metal in the mold, etc.

FIG. 6 is an explanatory diagram showing an example of the shaft-integrated resin magnet rotor manufacturing apparatus used in the experiment, in which the fixed side part,
Consists of moving sides and protrusions. The fixed side part and the movable side part each connect a fixed side mounting plate 11 and a cavity plate 12 made of a ferromagnetic material, and a moving side mounting plate 13 and a core plate 14 with a spacer block 15 made of a ferromagnetic material. A closed magnetic circuit generated by the internal electromagnetic coil 16 is constructed. Reference numerals 17 and 18 denote ferromagnetic blocks that are installed inside the electromagnetic coil 16 and protrude from the fixed side mounting plate 11 and the movable side mounting plate 13, respectively, and a non-magnetic cavity mold is placed between the opposing ferromagnetic blocks. 19 and a core mold 20 are arranged. A sprue lock pin 22 and a non-magnetic push-out pin 23 are connected to a protrusion plate 21 in the protrusion. 24 is a shaft placed before injection molding. Note that the cavity mold 19 and the core mold 2
0 is divided into several blocks for maintenance of the mold to prevent wear and tear caused by ferromagnetic powder during injection molding, arrangement of the holding structure for the shaft (not shown, and unnecessary if the device is vertical), configuration of the cooling water flow path, etc. It is often composed of

Next, a process of injection molding a shaft-integrated resin magnet rotor by applying a magnetic field using the apparatus shown in FIG. 6 will be described.

First, the entire moving side moves to the left and both molds 1
The shaft 24 is mounted on the core mold 20 with the shafts 9 and 20 open. Then, the entire movable side part is moved to the right side and the mold is clamped. Next, the mixture of thermoplastic resin and ferromagnetic powder injected at a predetermined temperature is passed through a nozzle port 25 provided on the fixed side mounting plate 11 to the fixed side mounting plate 11.
1, the fixed side ferromagnetic block 17 and the cavity mold 19, a part of it reaches the core mold 20, and further passes through the mating surfaces of the cavity mold 19 and the core mold 20 and enters the molded body space 27. It passes through the sprue runner 26 of the hollow passage leading to the molded body and fills the molded body space 27. During this time, the induced magnetic flux from the electromagnetic coil 16 flows through the mixture in the cavity mold 19 and the core mold 20, and a shaft-integrated resin magnet rotor with bipolar anisotropy in the radial direction is molded. After the molded body is cooled and solidified,
The entire moving side moves to the left and separates from the fixed side. When a certain distance is reached, the protruding plate 21 protrudes and the sprue lock pin 22 collects the solidified mixture in the sprue runner 26 of the core mold 20, and the non-magnetic extrusion pin 23 removes the solidified mixture in the molded body space 27. Extruded from the core mold 20,
Molding is completed.

Next, FIG. 5 shows the orientation state of the shaft-integrated resin magnet rotor molded in this manner by measuring the surface magnetic flux density distribution on the outer periphery of the rotor. The horizontal axis is the rotation angle θ, the vertical axis is the surface magnetic flux density B, and N and S indicate polarity. The molded body oriented with the apparatus shown in Fig. 6 is
The distribution is supposed to be a sinusoidal waveform as shown by the dotted line in the middle of Figure 5, but as shown by the solid line, the magnetic flux distribution waveform is distorted, and the peak deviates from the N and S pole positions, or the peak does not appear and becomes flat or curved. . As mentioned above, this disturbance in the magnetic flux distribution waveform is caused by a significant increase in the magnetic field gap and injection amount when molding the shaft-integrated resin magnet rotor while applying a magnetic field compared to conventional half-shaped molded products.
This seems to be due to the fact that oriented molding is difficult due to the influence of molten metal flow due to the shaft arrangement. This disturbance in the surface magnetic flux density distribution waveform is asymmetrical across the axis of the rotor, and cannot be put to practical use as a permanent magnet rotor of the synchronous motor shown in FIG. That is, this type of synchronous motor has difficulty in self-starting, and the disturbance and asymmetry of the surface magnetic flux density distribution waveform have a large influence. Further, such magnetic imbalance of the magnet rotor itself increases vibrations during rotation.

Means for Solving the Problems The technical aspects of the present invention solve the above-mentioned problems, that is, the point of eliminating disturbances in the surface magnetic flux density distribution waveform of the shaft-integrated resin magnet rotor and making it a symmetrical waveform through the shaft. The method is to form a ferromagnetic pin by standing upright from a ferromagnetic block housed in the electromagnetic coil, passing through a cavity mold and a core mold to reach the molded body.

Effect The effect of this technical means is as follows.
In other words, we installed ferromagnetic pins that penetrate the ferromagnetic block built into the electromagnetic coil, the cavity mold made of non-magnetic material, and the core mold to reach both poles of the rotor, which is a molded body. By guiding and concentrating the magnetic flux, the peaks of the magnetic flux density distribution waveform can be correctly located at both poles of the magnet rotor, and waveform disturbances can be eliminated, allowing the rotor to be used as a permanent magnet rotor for a synchronous motor.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. FIG. 1 shows an embodiment of the invention.
FIG. 2 shows a sectional view taken along line AA in FIG. The same members in FIGS. 1 and 2 as in FIG. 6 are given the same reference numerals.

In FIGS. 1 and 2, electromagnetic coil 1
A non-magnetic cavity mold 19 and a core mold 2 are installed in the ferromagnetic blocks 17 and 18 housed in
A plurality of ferromagnetic pins 30 are arranged at opposing positions to penetrate through the molded body space 27 and reach the molded body space 27. Reference numeral 31 denotes an extruded pin located in the same row as these ferromagnetic pins 30, and is made of a ferromagnetic material. These ferromagnetic pins 30
As is clear from FIG. 2, numerals 31 and 31 are arranged at the center of the magnetic poles at a mechanical angle of 180 degrees on the outer periphery of the rotor, and are opposed to each other with the shaft 24 interposed therebetween. FIG. 3 shows a perspective view of the molded body, in which a ferromagnetic pin 30,
31 pin marks 34 are located. A large number of these ferromagnetic pins can be arranged in a range B above the center of the magnetic pole in the axial direction as required. If the number of ferromagnetic pins is increased, the magnetic flux density at the center of the magnetic poles between the pins is increased, and the average magnetic flux density in the axial direction B as a whole becomes higher. If the non-magnetic capitivity mold 19 and the core mold 20 are not subdivided as described above and are integral molds at least around the molded body space, instead of arranging a large number of ferromagnetic pins in the axial direction, the pin diameter By arranging a ferromagnetic block (not shown) having a rectangular cross section with a width of approximately B and an axial length of approximately B, the magnetic flux density at the center of the magnetic pole in the B direction can be further made uniform.

Next, the effect of the ferromagnetic pin arrangement will be explained. FIG. 4 shows a magnetic flux density distribution waveform on the outer circumferential surface of a resin magnet rotor 33 manufactured by the structure of the present invention corresponding to the conventional structure shown in FIG. 5, and in which the shaft 24 is integrally molded. As is clear from Fig. 4, the magnetic flux from the electromagnetic coil 16 is forcibly induced and concentrated using the ferromagnetic pins 30 and 31 at positions facing each other at a mechanical angle of 180 degrees. Since the waveform disturbance can be made to closely approximate the original sinusoidal waveform (indicated by the dotted line) along this peak, bipolar symmetry is obtained through the axis 24. As a result, it became possible to use it as a permanent magnet rotor of a synchronous motor shown in FIG.

Effects of the Invention As is clear from the description of the embodiments described above, the present invention is advantageous in producing a resin magnet rotor by integrally insert-molding a shaft. A plurality of ferromagnetic pins that pass through the mold and the core mold and reach the molded object are installed in an opposing manner, and the magnetic flux from the electromagnetic coil is directed through the ferromagnetic pins to the center of both magnetic poles of the molded object, that is, the resin magnet rotor. By concentrating forced induction and molding, the disturbance in the magnetic flux distribution on the outer circumferential surface of the shaft-integrated insert resin magnet rotor is eliminated, peaks are formed correctly at both magnetic poles, and NS is transmitted through the shaft.
It is possible to obtain a product with a symmetrical magnetic flux density distribution at the pole, which eliminates the disadvantages of the conventional method of bonding half-split molded products due to the number of man-hours required, improving productivity and reducing costs. A shaft-integrated molded resin magnet rotor can be manufactured very advantageously, and its effects are great.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an apparatus for manufacturing a shaft-integrated resin magnet rotor used in an embodiment of the method for manufacturing a shaft-integrated resin magnet rotor of the present invention, and FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1. Figure 3 is a perspective view of the molded body, Figure 4 is a perspective view of the molded body.
The figure is a surface magnetic flux density distribution diagram on the outer periphery of a rotor, Figure 5 is a surface magnetic flux density distribution diagram on the outer periphery of a rotor molded using conventional equipment, and Figure 6 is a diagram of a general conventional shaft-integrated molded resin magnet rotor manufacturing equipment. The model sectional view and FIG. 7 are plan views showing an example of the configuration of a permanent magnet rotor type synchronous motor. ...Fixed side part, ...Movable side part, ...Protrusion part, 16...Electromagnetic coil, 17, 18...Ferromagnetic block, 19...Nonmagnetic cavity mold, 20...Nonmagnetic core Mold, 24...Shaft, 2
7...Molded object space, 30...Ferromagnetic pin, 31
...Ferromagnetic extrusion pin, 33...Resin magnet rotor,
34...Ferromagnetic pin trace.

Claims (1)

[Scope of Claims] 1. In a manufacturing device for a resin magnet rotor integrally molded with a shaft, which consists of a fixed part side and a movable part side, ferromagnetic blocks having electromagnetic coils on the outside are protruded and opposed to each other, and the ferromagnetic blocks are A cavity mold and a core mold made of non-magnetic material are provided between the molds, and after forming a molding space between the two molds and arranging the shaft, a mixture of thermoplastic resin and ferromagnetic powder is heated and exposed to a magnetic field. When manufacturing a shaft-integrated resin magnet by filling the molded body space by injection molding while applying an electric current, the molded body in the molded body space is passed from both ferromagnetic blocks through the cavity mold and the core mold, respectively. A plurality of ferromagnetic pins reaching up to A method for manufacturing a shaft-integrated resin magnet rotor, characterized by molding. 2. A method for manufacturing a shaft-integrated resin magnet rotor according to claim 1, wherein a plurality of ferromagnetic pins are formed into an integral ferromagnetic block continuous in the axial direction.