JPH07255152A - High-speed rotation motor rotor and method for manufacturing the rotor - Google Patents

Abstract

(57) [Summary] (Corrected) [Purpose] A rotor for a high-speed rotation motor that is comprehensively reinforced so that it is suitable for high-speed rotation, and that the plastic magnet is sufficiently reinforced and the magnetic efficiency is improved to some extent. And a manufacturing method is provided. [Structure] As the structure of the rotor 50, a molded product integrally formed by insert-molding a metal fitting attached to a shaft 16 of a motor with a plastic magnet 14 and an outer circular horizontal plate portion inside the plastic magnet 14 formed at the time of molding A reinforcing ring 52 is provided which is press fit into the outer wall of the vertical ring portion extending downwardly from the end. In the manufacturing process, a metal fitting attached to the shaft 16 of the motor is insert-molded with the plastic magnet 14 to be integrally molded, and the plastic magnet 14 is molded at the time of molding.
An inner circular horizontal plate portion and a vertical ring portion extending downwardly from an outer end of the circular horizontal plate portion,
The reinforcing ring 52 is press-fitted into the outer wall of the vertical ring portion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor for a high speed rotation motor and a method for manufacturing the rotor, and more particularly, to rotate a polygon mirror at a high speed for scanning a laser beam at a high speed by a laser beam printer (LBP). The present invention relates to a rotor for a high-speed rotation motor suitable for use in the above and a method for manufacturing the rotor.

[0002]

2. Description of the Related Art Conventionally, a rotor for a motor for rotating a polygon mirror has generally been formed by arranging ferrite magnets inside a metal member having a U-shaped cross section. When high-speed printing and high-speed stabilization (shortening of start-up time) of the rotor are required for high-speed printing in a laser beam printer, a small inertia is required, though it is a trade-off between rotation fluctuations during rotation. In order to reduce the inertia when the rotor rotates at high speed, it is required to reduce the weight of the rotor, and as a result, a lightweight plastic magnet has been used as a magnet portion of the rotor.

[0003] In plastic magnets, the molding conditions of the plastic magnet generally have an important influence on the strength of the plastic magnet. That is, depending on the molding conditions, the finished state of the surface is deteriorated, voids (cavities) are generated in the molded plastic magnet, or the composition is coarse and dense. These things reduce the strength of the plastic magnet,
The plastic magnet part may be destroyed by stress such as centrifugal force. Therefore, reinforcement by a metal member is usually performed (the magnetic efficiency is increased at the same time by reinforcement of the metal member), but if the weight of the metal member is increased, it is not preferable from the viewpoint of inertia and becomes unsuitable for high-speed rotation. . A motor rotor using a conventional plastic magnet will be described below.

FIG. 7, FIG. 8 and FIG. 9 are sectional views of a rotor using a conventional plastic magnet, respectively. In FIG. 7, the rotor 10 has a metal fitting 12 having a hole in the center, a plastic magnet 14, and a shaft 16. The metal fitting 12 and the plastic magnet 14 are the metal fitting 1
2 is insert-molded with a plastic magnet 14 to be integrally molded. The shaft 16 is fixed by being pressed into the central hole of the metal fitting 12. A polygon mirror 18 is placed on the upper surface of the metal fitting 12, and the shaft 1
6 with metal fitting 12 and shaft 1 by washer and E-ring
Fixed to 6.

The plastic magnet 14 includes an inner circular horizontal plate portion 14a, a vertical ring portion 14b extending downward from its outer end in parallel with the shaft 16, and a vertical ring portion 14b extending in parallel with the horizontal plate portion 14a. A horizontal ring portion 14c extending outward, a flange portion 14d extending upward from the outer end of the horizontal ring portion 14c in parallel with the shaft 16, and a ring-shaped extending downward from a lower surface slightly inward from the outer end of the horizontal ring portion 14c. Vertical protrusion 14e
Have. Vertical ring portion 14b, horizontal ring portion 14
The concave portion 1 whose top is opened by c and the brim portion 14d
4f is formed. In order to balance the weight, the concave portion 14f is formed by applying a weight to the inside of the concave portion 14f by applying an adhesive, for example, so that the center of gravity is on the rotation center line with the polygon mirror 18 attached to the shaft 16. Used. Balancing the weight at high speed is important in order not to exert an unreasonable force on the bearing (not shown) supporting the shaft 16 at high speed so as to extend the life of the bearing as much as possible. Is. Since the flange portion 14d is located outside the recess 14f, the adhesive is prevented from peeling outward due to centrifugal force when the rotor rotates at high speed. The Hall element 20 is arranged close to the outside of the vertical protrusion 14e in order to detect the rotational position and rotation speed of the rotor by sensing the magnetic poles magnetized in the vertical protrusion 14e. The vertical ring portion 14
The outer wall of b has a tapered shape that slightly expands downward.
Although not shown, a coil for generating an electromagnetic force for driving the rotor is arranged in the space 22 inside the plastic magnet 14, and a bearing for rotatably supporting the shaft 16 is provided. It is provided.

In FIG. 8, a rotor 30 has a metal fitting 12 having a hole in the center, an iron plate 32, a plastic magnet 14, and a shaft 16. The metal fitting 12, the iron plate 32, and the plastic magnet 14 are integrally formed by insert-molding the metal fitting 12 and the iron plate 32 with the plastic magnet 14. As is clear from the drawing, the iron plate 32 is integrated with a part of the upper surface of the circular horizontal plate portion 14a of the plastic magnet 14. The iron plate 32 used in this conventional example is used to reinforce the plastic magnet 14 and to improve the magnetic efficiency. Since the other configurations are similar to those of the conventional example of FIG. 7, detailed description thereof will be omitted.

In FIG. 9, a rotor 40 has a metal fitting 12 having a hole in the center, an iron plate 42, a plastic magnet 14, and a shaft 16. The metal fitting 12, the iron plate 42, and the plastic magnet 14 are integrally formed by insert-molding the metal fitting 12 and the iron plate 42 with the plastic magnet 14. As is clear from the drawing, the iron plate 42 is integrated with the entire upper surface of the circular horizontal plate portion 14a of the plastic magnet 14 and the outer peripheral wall portion thereof. Iron plate 3 used in this conventional example
2 is used to reinforce the plastic magnet 14 and to improve magnetic efficiency. Since the other configurations are similar to those of the conventional example of FIG. 7, detailed description thereof will be omitted.

[0008]

In the case of the rotor of FIG. 7,
Although it has an advantage that the inertia is small, it is not sufficient to counter the centrifugal force at the time of high-speed rotation because the plastic magnet is not reinforced, and the rotor may be damaged. Moreover, since there is no iron plate for reinforcement, it is not possible to expect an increase in magnetic efficiency.

In the case of the rotor shown in FIG. 8, the increase in magnetic efficiency can be solved, and the reinforcement has been solved to some extent, but it cannot be said to be sufficient. That is, when the metal fittings and the iron plate are insert-molded with the plastic magnet, the heat shrinkage rates of the metal and the plastic magnets such as the iron plate and the metal fittings are different. Decrease the strength of the plastic magnet. Also, as a matter of course, since the iron plate is used, the weight becomes large and the inertia cannot be made small.

The rotor of FIG. 9 is superior to the rotors of FIGS. 7 and 8 in terms of reinforcement and improvement of magnetic efficiency, but since the iron plate has the heaviest weight, the inertia becomes large. Therefore, it is impossible to achieve high-speed rotation as used in LBP. In addition, since the heat shrinkage rates of the metal and the plastic magnet are different, there is a drawback that after molding, a change with time due to temperature occurs, cracks and sink marks occur, and the strength of the plastic magnet is weakened.

Therefore, the first object of the present invention is to keep the inertia small so as to be suitable for high-speed rotation, to sufficiently reinforce the plastic magnet without causing a change with time, and to improve the magnetic efficiency to some extent. The object is to provide a comprehensively excellent rotor for a high-speed rotation motor.

A second object of the present invention is to provide a manufacturing method for manufacturing a rotor of a motor for high speed rotation which is comprehensively excellent as described above.

[0013]

In order to achieve the above-mentioned first object, the present invention relates to a molded product which is integrally molded by insert-molding a metal fitting attached to a shaft of a motor with a plastic magnet, and a molded product formed at the time of molding. And a reinforcing ring press-fitted into the outer wall of the vertical ring portion extending downward from the outer end of the circular horizontal plate portion on the inner side of the formed plastic magnet, and the rotor of the motor for high-speed rotation is adopted. . It is preferable that the reinforcing ring has a taper shape before press-fitting, and is deformed flat from the taper shape to the horizontal direction by press-fitting.

In order to achieve the second object, according to the present invention, a metal fitting attached to a shaft of a motor is insert-molded by a plastic magnet and integrally molded, and a circular horizontal plate portion inside the plastic magnet is formed at the time of the molding. And a vertical ring portion that extends downward from the outer end of the circular horizontal plate portion, and a reinforcing ring is press-fitted into the outer wall of the vertical ring portion. To do. It is preferable that the reinforcing ring has a taper shape before press-fitting, and is deformed flat from the taper shape to the horizontal direction by press-fitting.

[0015]

Embodiments of the rotor of the motor for high speed rotation according to the present invention will be described below.

(Embodiment 1) FIG. 1 is a schematic sectional view of a rotor of Embodiment 1 of the present invention, and FIG. 2 is a partially enlarged schematic sectional view of a rotor of Embodiment 1. 1 and 2, the rotor 50 has a metal fitting 12 having a hole in the center, a plastic magnet 14, and a shaft 16. The metal fitting 12 and the plastic magnet 14 are integrally molded by insert-molding the metal fitting 12 with the plastic magnet 14. The shaft 16 is fixed by being pressed into the central hole of the metal fitting 12. A polygon mirror 18 is placed on the upper surface of the metal fitting 12, and is fixed to the metal fitting 12 and the shaft 16 by a washer and an E ring.

The plastic magnet 14 has an inner circular horizontal plate portion 14a, a vertical ring portion 14b extending downward from its outer end in parallel with the shaft 16, and a vertical ring portion 14b extending in parallel with the above-mentioned horizontal plate portion 14a. A horizontal ring portion 14c extending outward, a collar portion 14d extending upward from the outer end of the horizontal ring portion 14c in parallel with the shaft 16, and a ring-shaped extending downward from a lower surface slightly inward from the outer end of the horizontal ring portion 14c. Vertical protrusion 14e
Have. Vertical ring portion 14b, horizontal ring portion 14
The concave portion 1 whose top is opened by c and the brim portion 14d
4f is formed.

A reinforcing ring 52 is placed in the recess 14f and is attached to the plastic magnet 14 while being press-fitted into the lower end of the outer wall of the vertical ring portion 14b.
The reinforcing ring 52 is press-fitted to press the vertical ring portion 14b.
Since it is mounted so as to bite into the lower end of the outer wall, the reinforcing ring 52 is prevented from coming off. The shape, manufacturing method, attachment method to the plastic magnet, etc. of the reinforcing ring 52 will be described later in detail, but the reinforcing ring 52 is formed in a tapered shape in the concave portion 14f.
It is installed by press-fitting into it using a press. In the state where the reinforcing ring 52 is attached, the width direction of the reinforcing ring 52 is horizontal and has a sufficient length against centrifugal force, so that the plastic magnet can be sufficiently reinforced. As a material of the reinforcing ring 52, any suitable metal material such as SUS, aluminum, or brass is selected. Which material is selected is mainly determined by the strength and magnetic permeability depending on the case. Further, since the reinforcing ring 52 is a metal material having magnetic permeability, it also has a function of improving magnetic efficiency.

The above-mentioned recess 14f is formed by the polygon mirror 18
With the ring attached to the shaft 16 and the ring 52 attached to the plastic magnet 14, a weight is formed by applying a weight to the center of rotation by applying an adhesive, for example, so that the center of gravity is on the rotation center line. Used to take. Balancing the weight at high speed is important in order to extend the life of the bearing by preventing unreasonable force from being applied to the bearing (not shown) supporting the shaft 16 at high speed. Is. Since the flange portion is outside the recess, the adhesive is prevented from peeling outward due to centrifugal force when the rotor rotates at high speed. The Hall element 20 is arranged close to the outside of the vertical protrusion 14e in order to detect the rotating position and the rotation speed of the rotor by sensing the magnetic poles magnetized in the vertical protrusion 14e. The outer wall of the vertical ring portion 14b has a tapered shape that slightly expands downward.

Next, a method of manufacturing the rotor of the present invention will be described with reference to FIG. First, a flat ring is stamped and formed from a plate using a press having an upper die 60 and a lower die 62 having a shape as shown in FIG. 3A (the ring 52 shown in FIG. 3A is formed). Later ones). Next, the upper die 6 having a shape as shown in FIG.
Using a press with 4 and lower die 66, the flat ring is tapered to form the reinforcing ring. Next, as shown in FIG. 3 (c), the tapered reinforcing ring 52 is manually placed in the recess of the integrally molded metal fitting and plastic magnet shown in FIG. 1 formed by separate molding. Then, the tapered reinforcing ring 52 is flatly deformed by using a press having an upper die 68 and a lower die 70 as shown in FIG. 3D, and the lower end of the outer wall of the vertical ring portion of the plastic magnet is deformed. Press into. After that, as in the conventional example, a polygon mirror is attached and an adhesive weight is applied to balance the weight.

Next, the results of a fracture test conducted to compare the first embodiment of the present invention with the conventional example will be described. FIG. 4 is a graph showing the breaking rate (vertical axis) against the breaking rotation speed (horizontal axis). As is apparent from FIG. 4, in the rotor of the conventional example having no reinforcing ring as shown in FIG. 7, some of the rotors are destroyed when the rotation speed exceeds about 20,000, and the rotor is destroyed near 40,000 rotations. The number of people rises sharply. On the contrary,
The rotor of the present invention does not appear to break up to around 40,000 rpm. Therefore, the rotor of the high-speed rotation motor of the present invention can be safely used up to about 40,000 rotations.

(Embodiment 2) FIG. 5 is a schematic sectional view showing Embodiment 2 of the rotor of the present invention. In the second embodiment, instead of attaching the tapered reinforcing ring used in the first embodiment to the plastic magnet, a reinforcing ring 54 having a length in the axial direction of the motor is used. The reinforcing ring 54 is attached by being press-fitted into the vertical ring portion 14b of the rotor because the vertical ring portion 14b has a tapered shape that slightly expands downward. The reinforcing ring 54 of the second embodiment is inferior in strength to the reinforcing ring 52 of the first embodiment, but is excellent in improving the magnetization efficiency.

If desired, the reinforcing ring of either Example 1 or Example 2 can be selectively used.

Finally, FIG. 6 shows a detailed cross section of the entire motor of the present invention and the printed circuit board on which the motor is mounted. Reference numeral 100 indicates the entire motor, and reference numeral 102 indicates a printed circuit board on which the motor is mounted. Ring 52 of the first embodiment
(Not shown) or 54 (not shown) of the second embodiment is attached to the plastic magnet 14 as described above while being placed in the recess 14f. Reference numeral 104 indicates a coil.

[0025]

As described in detail above, according to the present invention, the inertia can be kept small, the plastic magnet is sufficiently reinforced without causing a change with time,
In addition, a rotor for a high-speed rotation motor that is comprehensively excellent in that the magnetic efficiency can be improved to some extent can be obtained. Also,
It is possible to obtain a manufacturing method of such a comprehensive rotor rotor for a high-speed rotation motor.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a rotor according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged schematic sectional view of the rotor of the first embodiment.

FIG. 3 is a diagram for explaining a rotor manufacturing process.

FIG. 4 is a graph showing a fracture rate (vertical axis) with respect to a fracture rotational speed (horizontal axis) in an experiment.

FIG. 5 is a schematic sectional view of a rotor according to a second embodiment of the present invention.

FIG. 6 is a detailed cross-sectional view showing the entire high-speed rotation motor of the present invention.

FIG. 7 is a schematic cross-sectional view showing a rotor of a conventional motor.

FIG. 8 is a schematic cross-sectional view showing a rotor of another conventional motor.

FIG. 9 is a schematic sectional view showing a rotor of a motor of still another conventional example.

[Explanation of symbols]

 50 Rotor for High Speed Rotation Motor 12 Metal Fitting 14 Plastic Magnet 16 Axis 18 Polygon Mirror 20 Hall Element 22 Internal Space 52 Ring (Example 1) 54 Ring (Example 2) 100 Motor 102 Printed Circuit Board 104 Coil

Claims (7)

[Claims] 1. A molded product integrally formed by insert-molding a metal fitting attached to a motor shaft with a plastic magnet, and a vertical ring extending downward from an outer end of a circular horizontal plate portion inside the plastic magnet formed at the time of molding. A rotor for a high-speed rotation motor having a reinforcing ring press-fitted into an outer wall of the portion. 2. The rotor for a high-speed rotation motor according to claim 1, wherein the reinforcing ring has a tapered shape before press-fitting, and the press-fitting deforms the taper flat horizontally in a horizontal direction. High-speed rotation motor rotor. 3. The rotor of a motor for high speed rotation according to claim 2, wherein the plastic magnet is formed of a horizontal ring portion extending horizontally outward from the vertical ring portion and a brim portion extending upward from the horizontal ring portion. A rotor for a high-speed rotation motor, further comprising a concave portion, and the reinforcing ring is placed on a bottom portion of the concave portion. 4. The rotor for a high-speed rotation motor according to claim 1, wherein the reinforcing ring has a width in the axial direction of the motor, and the inner side of the reinforcing ring is press-fitted so as to contact the vertical ring portion. Characteristic high-speed rotation motor rotor. 5. A metal fitting to be mounted on a shaft of a motor is insert-molded with a plastic magnet to be integrally molded, and at the time of molding, a circular horizontal plate portion inside the plastic magnet and an outer end of the circular horizontal plate portion extend downward. A method for manufacturing a rotor for a high-speed rotation motor, which comprises forming a vertical ring portion and press-fitting a reinforcing ring into an outer wall of the vertical ring portion. 6. The method of manufacturing a rotor for a high-speed rotation motor according to claim 5, wherein the reinforcing ring is stamped from a plate by stamping, and the stamped ring is formed into a tapered shape by stamping. A method for manufacturing a rotor for a high-speed rotation motor, which is characterized in that 7. The method of manufacturing a rotor for a high-speed rotation motor according to claim 5, wherein when the reinforcing ring is press-fitted into the outer wall of the vertical ring portion, the reinforcing ring is deformed flat from a tapered shape to a horizontal direction. A method for manufacturing a rotor of a high-speed rotation motor, which is characterized by the above.