JP2942434B2 - Rotor for stepping motor and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin rotor used for, for example, a permanent magnet type stepping motor and a method for manufacturing the rotor.

[0002]

2. Description of the Related Art For example, a permanent magnet type stepping motor has a stator yoke having magnetic pole teeth disposed so as to face a resin rotor rotatably supported. This resin rotor is, for example, as shown in FIGS. 9 and 10 , a permanent magnet 1 formed in a hollow cylindrical shape, a shaft 3 located at the center of the permanent magnet 1, and a boss 5 into which the shaft 3 fits. And a mold resin 7 for integrally fixing and molding the inner periphery of the permanent magnet 1.

In manufacturing such a resin rotor, as shown in FIG. 11 , a cylindrical space is formed inside a molding die 9 and a cylindrical permanent magnet 1 and a center of the permanent magnet 1 are formed therein. The shaft 3 disposed in the vertical direction is arranged, and the resin is injected and filled, for example, and the two are connected and fixed.

The end face of the permanent magnet 1 of the resin rotor manufactured as described above has a portion having a dimension L which is about half the thickness thereof is exposed ( FIG. 9 ). That is, the end face of the permanent magnet 1 was covered with the radially inner side by about half by the resin flange 11 extending in the radial direction by about half the thickness of the permanent magnet. The reason that the half is exposed and the half is covered with the resin is that when the permanent magnet 1 is vertically arranged in the molding die 9, the lower end of the permanent magnet 1 is positioned at the bottom of the molding die 9 for positioning. This is because it is necessary to make contact.

[0005]

If the outer peripheral edge of the end face of the permanent magnet 1 exposed in this way comes into contact with a stator yoke or the like at the time of assembling a stepping motor, chipping or cracking may occur, and the resin rotor may be damaged. In some cases, such as when the edge is accidentally dropped, the edge may be completely damaged. When such chipping, cracking or breakage occurs, the resin rotor becomes a defective product.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a rotor for a stepping motor and a method for manufacturing the same, which can prevent chipping, cracking or breakage at the outer peripheral edge of the end face. The purpose is to do.

[0007]

To achieve the above object, according to the Invention The first invention of this application, a cylindrical permanent magnet disposed for forming Katachikin the type, the axis center of the permanent magnet vertically In the method for manufacturing a stepping motor rotor in which a resin is filled in the molding die and the two are connected and fixed, the lower end surface of the cylindrical permanent magnet is supported at the bottom of the molding die. Material is provided, and the support material is provided so as to be able to protrude and retract from a hole formed on the inner surface of the molding die, and is immersed in the hole when the resin is filled and molded. 4 is a method for manufacturing a rotor for a stepping motor.

As shown in the second aspect of the invention, the retractable support member is provided via a spring, is immersed in the hole by the pressure of the resin to be filled, and the rotor molded product is taken out of the molding die. When it is released, it can be returned to the original position by the restoring force of the spring.

According to a third aspect of the present invention, there is provided a rotor for a stepping motor in which a cylindrical permanent magnet and a shaft disposed at the center of the permanent magnet are connected and fixed by a resin. A stepping motor rotor, wherein a spacer is integrally fixed, and the resin extends in a flange shape to the outer peripheral edge of the end face through the spacer or the gap between the spacers.

According to a fourth aspect of the present invention, a cylindrical permanent magnet is arranged in a molding die, an axis is vertically arranged at the center of the permanent magnet, resin is filled in the molding die, and the two are connected. In the method of manufacturing a fixed stepping motor rotor, a spacer that supports a lower end surface of the cylindrical permanent magnet is disposed at the bottom of the molding die, and the resin and the spacer are integrally fixed during molding. And a step of extending the resin to the outer peripheral edge of the lower end surface through the spacer or a gap between the spacers.

[0011]

[Function] Resin up to the outer peripheral edge of both end faces of cylindrical permanent magnet
To extend to flange shape, the lower end surface of the permanent magnet capable provided is support haunt from forming metal mold hole portion formed in the inner surface of the support, a bottom portion of the molding die and the lower end face dividing line depending on the provision of the gap between. The support member is provided via a spring, and is immersed in the molding die by using the pressure of the resin to be filled. When the rotor molded product is taken out from the molding die, the spring has a restoring force. Can return to the original position.

In addition, the lower end surface of the cylindrical permanent magnet may be supported by a spacer instead of the supporting member, and the resin may be extended in a flange shape through a gap between the spacers. The spacer remains integrally fixed to the end face of the permanent magnet of the manufactured rotor.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of a rotor for a stepping motor,
As shown in FIGS. 1 and 2, two cylindrical permanent magnets 1 are arranged side by side in the longitudinal direction of a shaft 3. The permanent magnet 1 and the shaft 3 are connected and fixed by a resin 7. That is, the shaft 3 is fitted in the boss 5 formed of resin, and the rib 6 continuous with the boss 5 is integrally continuous with the resin 7 on the inner periphery of the permanent magnet 1.

The resin 7 forms a flange 11 reaching the outer peripheral edges of both end faces of the cylindrical permanent magnet 1. That is, radial portions 13 are formed on the lower end face at a pitch of 120 ° in the circumferential direction of the rotor as shown in FIG. The distal end of each radial portion 13 reaches the outer peripheral edge. The distal end extends in the circumferential direction to form a thin ring-shaped portion 15. The radial dimension of the ring-shaped portion 15 is about １ ／ of the thickness of the cylinder of the permanent magnet 1. A substantially fan-shaped recess 17 is provided between the radial portions 13.
And is not covered with the resin 7.

[0015] The Contact, not formed with the recess 17 as described above in the flange 11 of the upper end face of the permanent magnet 1, the permanent magnet 1
There is no exposed part, but the flange 1 on the upper end face side of the permanent magnet 1
1 may also be formed with the same concave portion 17 as the lower end surface side.

The rotor shown in FIGS. 1 and 2 is manufactured by forming a substantially fan-shaped projection (not shown) on the bottom of a molding die. That is, the cylindrical permanent magnet 1 and the shaft 3 located at the center of the cylindrical shape are vertically arranged in the cylindrical space of the molding die as in the related art. Two permanent magnets 1
A spacer 2 is provided between them, and the permanent magnet 1, the spacer 2, and the permanent magnet 1 are arranged in a state of being sequentially stacked in the longitudinal direction of the shaft 3. Three substantially fan-shaped protrusions are formed at the bottom of the molding die at intervals of 120 °. The radially outer end of the substantially fan-shaped projection contacts and supports up to about １ ／ of the thickness of the lower end surface of the permanent magnet 1. By this contact, the positioning of the permanent magnet 1 is performed.

When the resin is injected and filled after the permanent magnet 1 and the shaft 3 are arranged, the resin goes around through the gap between the protrusions and reaches the outer peripheral edge of the permanent magnet 1. This makes Tsuba 1
One radial portion 13 and a ring-shaped portion 15 are formed. In addition, since it is not necessary to provide a projection for positioning on the upper end surface of the permanent magnet 1, the concave portion 17 as described above cannot be formed, and the entire upper end surface is covered with the flange 11 of the resin 7.

As described above, according to the examples shown in FIGS. 1 and 2 , the lower end surface of the permanent magnet 1 has a concave portion 17 and a portion where the end surface of the permanent magnet 1 is exposed. Since the outer peripheral edge portion is covered with the resin 7, it is possible to protect a portion which is likely to come into contact with another component, for example, an adjacent stator yoke at the time of assembling the stepping motor, and to suppress occurrence of chipping or cracking. In addition, it is possible to reduce the possibility that the rotor will be damaged if the rotor is accidentally dropped.

In the above example , the projection for supporting the lower end surface of the permanent magnet 1 has a substantially fan shape, and thus the concave portion 17 also has a substantially fan shape. However, in the other examples shown in FIGS. The projections are small cylindrical or hemispherical as shown in FIG.
And the exposed area of the end face of the permanent magnet 1 can be reduced.

Further, the number of the permanent magnets 1 was two.
However, the number may be one or three or more.

[0021] Next, the actual施例of the present invention based on FIG. Ie before is provided with the projections at the bottom of the mold 9 in clean, this embodiment includes a support member 19 retractable within the circumferential bottom of the mold 9. In this embodiment, the support member 19 is a cylindrical movable pin placed horizontally, and a cylindrical hole 21 formed in a side wall near the bottom of the molding die 9.
Is provided via a spring 23 therein. The four supporting members 19 are provided, for example, at equal intervals in the circumferential direction of the inner periphery of the bottom of the molding die 9. As the spring 23, a spring having a spring constant that can be sufficiently compressed by the pressure of the resin injected and filled and can be immersed inside the hole 21 is selected. The eject pins 25 are provided at positions that do not interfere with the four support members 19 provided.

When the resin is injected, the space between the permanent magnet 1 and the shaft 3 is gradually filled with the resin. Eventually, the resin reaches the bottom of the molding die 9 and the filling pressure of the resin reaches the support member 19. Due to this pressure, the support member 19 retreats against the restoring force of the spring 23 and enters the hole 21.
By the time of the immersion, the permanent magnet 1 is supported by the filled resin, and a gap is maintained between the lower end surface of the permanent magnet 1 and the molding die 9. The resin wraps around this gap and extends in a flange shape over the entire lower end surface of the permanent magnet 1.

In the embodiment shown in FIG.
Is to immerse into the hole 21 by using the pressure of the resin to be injected and filled, but in another embodiment not shown, the support member 19 is moved by electric or mechanical means. Thus, it can be made to be able to appear and disappear from the hole 21. In this way, the support member 19 can be made to protrude and retract by adjusting the injection / holding timing of the resin and the operation timing of the electrical or mechanical means.

Next, an embodiment according to the second and third aspects of the present invention will be described with reference to FIGS. Chi words, in the present embodiment the spacer 27 is disposed on the bottom of the mold 9, the spacer 27 is the portion of the rotor are integrally fixed to the rotor after the resin injection molding.

The spacer 27 has, as shown in FIG. 7, for example, a protective flange portion 29 for completely covering and protecting the lower end surface of the cylindrical permanent magnet 1 and a short cylindrical shape inserted on the inner peripheral side of the permanent magnet 1. And an engaging portion 33 protruding inward from an end of the inserting portion 31 and engaging with the inside of the resin.

The spacer 27 is arranged at the bottom of the molding die 9, and the lower end surface of the permanent magnet 1 is placed thereon for positioning. The spacer 27 and the permanent magnet 1 are connected and fixed by a resin that is filled thereafter. In this embodiment, in particular, the engaging portion 33 of the spacer 27 is engaged so as to bite into the resin,
It helps to fix the spacer 27 and the resin 7 together.

The upper end surface of the permanent magnet 1 does not need to be in contact with the lower end surface for positioning.
7 need not be provided.

The embodiment shown in FIGS.
Used to cover and protect the entire lower end surface of the permanent magnet 1, but as shown in FIG. 8, simply provide a predetermined gap between the lower end surface of the permanent magnet 1 and the bottom of the molding die 9. Can be just for you.

That is, the spacer 27 in FIG. 8 has a thin ring shape, and has a zigzag shape in which irregularities are repeated in the axial direction of the cylindrical permanent magnet 1. The gap between the permanent magnet 1 and the bottom of the molding die 9 is secured by the height H in the axial direction of the step of the uneven portion. The spacer 27 is also embedded in the resin 7 and is integrally fixed. At the time of molding, the resin extends radially outward through a zigzag gap of the spacer in a flange shape. The portion extended in a flange shape reaches the inner peripheral side wall of the molding die 9 and covers the outer peripheral edge of the lower end surface of the permanent magnet 1.

The shape of the spacer 27 is not limited to those shown in FIGS. 7 and 8, but may be other various shapes. In short, the spacer 27
The material that covers the entire lower end surface of the permanent magnet 1 only needs to have a material or a shape that can secure the integral fixation with the resin. In the case where the lower end surface is covered by a flange-shaped resin portion extending through the spacer 27, the resin can sufficiently extend around the lower end of the permanent magnet 1 so as to extend.
Any material that can secure a gap of a predetermined height between the lower end surface of the permanent magnet 1 and the bottom surface of the molding die 9 may be used.

Further, in the sectional views of the rotor shown in FIGS. 1, 3 and 6, a hollow portion (around the boss portion 5) formed for weight reduction is shown. These hollow portions are formed by convex portions provided on a male mold and the like mounted on the molding die 9 shown in FIG. 5, but the convex portions are provided for simplifying the drawing. Are omitted from the drawing.

[0032]

As described above, according to the present invention,
The resin for coupling and fixing the permanent magnet and the shaft, by providing for extended to the outer peripheral edge of the cylindrical end surfaces of the permanent magnets, the possible support infested in the bottom peripheral surface of the forming metal mold, the The portion of the permanent magnet that abuts on the projection can be prevented from being exposed and left without being covered with the resin.

In particular, the supporting member is provided via a spring for urging the molding die inward, and is applied to the inner peripheral surface of the molding die against the urging force of the spring by the filling pressure of the resin during injection molding. If it is immersed, the support material can be moved only by filling the resin, and the support material returns to the original position immediately after removing the molded product, thereby simplifying the operation.

Further, if the outer peripheral edge of the lower end face of the permanent magnet is covered by a flange-like portion of the resin extending through the spacer for the end face or the spacer, the immersible support member is provided. It is possible to prevent the exposed portion from remaining on the end face of the permanent magnet by simpler means.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a stepping motor rotor.

FIG. 2 is a bottom view of FIG. 1;

FIG. 3 is a cross-sectional view showing another example of a stepping motor rotor.

FIG. 4 is a bottom view of FIG. 3;

FIG. 5 is a stepping motor according to a first embodiment of the present invention;
It is a sectional view showing a method for manufacturing a.

FIG. 6 shows a step manufactured according to the second embodiment of the present invention .
It is sectional drawing of a ping motor .

FIG. 7 is a partially cutaway perspective view showing one embodiment of a spacer used in FIG. 6;

FIG. 8 is a perspective view showing another embodiment of the spacer used in FIG. 6;

FIG. 9 is a sectional view of a conventional rotor for a stepping motor.
is there.

FIG. 10 is an end view of FIG . 9;

FIG. 11 is a view for explaining a method of manufacturing the rotor of FIG . 9;
You.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 permanent magnet 3 shaft 5 boss 7 resin 9 molding die 11 flange 13 radial portion 15 ring-shaped portion 17 concave portion 19 support material 21 hole 23 spring 27 spacer 29 protective flange 31 insertion portion 33 engagement portion

──────────────────────────────────────────────────続 き Continuation of the front page (72) Mitsuo Kinoshita 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (56) References JP-A-58-12562 (JP, A) JP-A-58-12562 JP-A-4-71351 (JP, A) JP-A-6-245472 (JP, A) JP-A-57-195375 (JP, U) JP-A-62-64177 (JP, U) (58) Fields investigated (Int) .Cl. ⁶ , DB name) H02K 37/00-37/24

Claims (4)

(57) [Claims] 1. A cylindrical permanent magnet is arranged in a molding die.
An axis is vertically arranged at the center of the permanent magnet,
Stepping to fill and fix resin in mold
In the method for manufacturing a rotor for a motor, the bottom of the molding die
A support member for supporting the lower end surface of the cylindrical permanent magnet in the portion
The support is provided with a hole formed in an inner surface of the molding die.
And the resin is filled
Characterized in that it is immersed in the hole when molding is performed.
Manufacturing method for a stepping motor rotor. 2. The support member, which can be moved in and out, includes the molding die.
Is provided through a spring for urging the inward of the
It is immersed in the hole by the pressure of the resin filled in the mold
At the same time, the rotor molded product is taken out of the molding die.
When it is released, it returns to the original position by the restoring force of the spring
The stepping motor according to claim 1, wherein
Of manufacturing rotors for motor vehicles. 3. A cylindrical permanent magnet and a center of the permanent magnet.
Steppin with connected shaft fixed by resin
End of the cylindrical permanent magnet
The surface is provided with a spacer integrally fixed with the resin,
The resin is passed through the gap of the spacer or spacer.
It is characterized by being extended in a flange shape to the outer peripheral edge of the end face
For a stepping motor. 4. A cylindrical permanent magnet is arranged in a molding die.
An axis is vertically arranged at the center of the permanent magnet,
Stepping to fill and fix resin in mold
In the method for manufacturing a rotor for a motor, the bottom of the molding die
Spacer supporting the lower end surface of the cylindrical permanent magnet at the portion
Are arranged, and the resin and the spacer are integrally formed during molding.
Through the spacer or the gap between the spacers.
Extending the resin to the outer peripheral edge of the lower end face.
A method for manufacturing a rotor for a stepping motor.