JP2002369463A - Method of manufacturing rotor provided with fg - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the time which is required for a molten plastic magnet to reach the outer circumference of a rotor plate uniform over the whole outer circumference to avoid formation of weld line. SOLUTION: This rotor 10 with an FG includes a rotor plate 12, and a plastic magnet 14 is provided on the outer circumference of the rotor plate 12. In order to manufacture the rotor 10, the rotor plate 12 manufactured in a separated process is prepared. The rotor plate 12 is placed in the upper and the lower molds and molten plastic magnet 14 is injected through one gate formed, so as to face a shaft hole 12a. The molten plastic magnet flows on the rotor plate 12 radially from the center and fills the cavity. After the molten plastic magnet is cured to some extent, the molds are separated, and the plastic magnet 14 which has formed on the upper surface of the rotor plate 12 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a rotor with an FG, and more particularly to a method of manufacturing a rotor with an FG used for controlling the rotation of a capstan motor provided in, for example, a VCR.

[0002]

2. Description of the Related Art In a conventional method of manufacturing this type of rotor with FG, a plurality of rotors 1 with FG (see FIG. 7C) are manufactured (formed) at a time. As shown, a runner 2 is configured, and a mold including an upper mold 3a and a lower mold 3b is arranged. As shown in FIG. 7B, the upper and lower dies are connected to the runner 2, and the rotor plate 4 is disposed so as to be sandwiched between the upper and lower dies 3a and 3b. When the melt of the plastic magnet 6 is injected from the sprue 5, the melt is passed through the runner 2 to the rotor plate 4.
Into the cavity 7 formed outside the side wall 4a. When the melt of the plastic magnet 6 is filled in the cavity 7 and injection of the melt is completed, the upper and lower molds are released after the melt has hardened to some extent. And
Unnecessary portions (side surfaces) of the plastic magnet 6 were cut off to form the FG-equipped rotor 1 as shown in FIG. 7C.

[0003]

However, in this prior art, the melt of the plastic magnet 6 flows into the cavity 7 from the two directions through the runner 2, so that the weld line of the melt of the plastic magnet 6 is joined at the portion where the melts join. Had occurred. Although illustration is omitted,
When the FG-equipped rotor 1 in which such a weld line is generated is mounted on a VCR and used, there is a problem that an error occurs in the rotation control of the capstan motor.

[0004] In order to avoid this, an example of the prior art for preventing the occurrence of a weld line is disclosed in
It is disclosed in Japanese Patent Laid-Open Publication No. Hei 3-78453, filed on March 3 [H02K 15/12, H02K 15/04]. In this method of manufacturing an amateur for a flat motor, an annular projection is provided on the upper and lower molds, a molten resin is injected into a space formed by the annular projection, and after the molten resin is filled in the space, the armature is removed from the space. It is made to flow radially outward in the radial direction of the coil.

However, in this prior art, since a plurality of gates are provided, in order to make the molten resin flow radially, it is necessary to equalize the amount of the molten resin injected into each gate. It was troublesome to adjust the injection amount.

[0006] Therefore, a main object of the present invention is to provide a method of manufacturing a rotor with an FG, which can prevent the occurrence of weld lines and can be easily manufactured.

[0007]

A first invention is a method of manufacturing a rotor with an FG used for controlling the rotation of a capstan motor provided in a VCR, which has a side wall on the outer periphery and a shaft hole in the center. And preparing a disk-shaped rotor plate provided with at least one holding hole, preparing an upper die having one gate at a position facing the shaft hole, and inserting the shaft pin inserted into the shaft hole and the holding hole. Preparing a lower mold having at least one holding pin, inserting a shaft pin into a shaft hole, inserting a holding pin into the holding hole, mounting a rotor plate on the lower mold, and combining the lower mold and the upper mold. A cavity is formed on the outside of the side wall of the rotor plate and on the upper surface side of the rotor plate, and a melt of the plastic magnet is injected into the cavity from the gate of the upper die, and after the melt is injected. It was to ablate the upper surface plastic magnet of Tapureto a method for manufacturing a FG with the rotor.

A second invention is a method of manufacturing a rotor with an FG for use in controlling the rotation of a capstan motor provided in a VCR, the method comprising a shaft hole and at least one holding hole in the center having a side wall on the outer periphery. Is prepared, an upper die having one gate is provided at a position facing the shaft hole, and a shaft pin inserted into the shaft hole and at least one holding pin inserted into the holding hole are prepared. Prepare a lower mold having a, insert the shaft pin into the shaft hole and insert the holding pin into the holding hole, attach the rotor plate to the lower mold,
A method of manufacturing a rotor with an FG, wherein a cavity is formed by combining a lower mold and an upper mold, and a melt of a plastic magnet is injected from the gate of the upper mold into the cavity.

[0009]

The FG-equipped rotor is used to control the rotation of a capstan motor provided in a VCR, and uses a rotor provided integrally with the rotation shaft of the capstan motor and a belt such as a timing belt. Connected. When manufacturing such a rotor with FG, a disk-shaped rotor plate is prepared. This rotor plate is provided with a shaft hole through which the rotating shaft of the FG-equipped rotor passes and at least one holding hole for fixing the rotor plate when the FG-equipped rotor is manufactured. Also,
A side wall is provided on an outer peripheral portion of the rotor plate 12. Such a rotor plate is formed in another process and is prepared in advance. Also, an upper die having one gate at a position facing the shaft hole is prepared, and a lower die having a shaft pin inserted into the shaft hole and at least one pressing pin inserted into the holding hole is prepared. Next, the shaft pin is inserted into the shaft hole, the holding pin is inserted into the holding hole, and the rotor plate is mounted on the lower die.

Subsequently, the lower mold and the upper mold are combined, and a molten plastic magnet is injected from the gate. Then, the melt of the plastic magnet flows radially from the center on the rotor plate and fills the cavity formed by the combination of the upper and lower molds. As described above, since the melt of the plastic magnet flows radially, the time required for the melt of the plastic magnet to reach the side wall (outer periphery) of the rotor plate can be made uniform over the entire outer periphery of the rotor plate.

Further, the cavity formed by the upper and lower molds as described above is formed on the outside of the side wall of the rotor plate and the upper mold of the rotor plate, and after injecting the melt of the plastic magnet, the melt is formed. After curing to some extent, the mold is released, and unnecessary plastic magnets that are present (reside) on the upper surface side of the rotor plate are cut off. As described above, the unnecessary plastic magnets are only the portions staying on the upper surface side of the rotor plate. For example, if the molten material of the plastic magnets is injected by using a hot runner, the waste such as staying in the runner portion is generated. It is possible to reduce unnecessary plastic magnets. That is, manufacturing costs can be reduced.

For example, when the melt of the plastic magnet passes near the holding hole, it flows along the outer periphery of the holding hole due to its surface tension. Therefore, if the holding hole is formed in an elliptical shape having a major axis in the same direction as the radial direction of the rotor plate, no time delay occurs when the melt of the plastic magnet passes near the holding hole. Therefore, there is no difference in the time required for the melt of the plastic magnet that has passed near the holding hole and the melt of the plastic magnet that has passed away from the holding hole to reach the outer peripheral portion of the rotor plate. Generation can be prevented.

[0013]

According to the present invention, the time required for the molten material of the plastic magnet to flow radially and reach the outer peripheral portion of the rotor plate is made uniform, so that the occurrence of weld lines in the plastic magnet can be prevented. it can.

Further, since the molten material of the plastic magnet is only injected from one gate provided on the upper mold, the adjustment of the injection amount is relatively simple, and it is possible to manufacture easily.

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the accompanying drawings.

[0016]

Referring to FIG. 1, a rotor 10 with an FG according to this embodiment includes a rotor plate 12;
Are formed in a disk shape. At the center of the rotor plate 12, there is provided a shaft hole 12a through which the rotation shaft (see FIG. 3) of the FG-equipped rotor 10 passes. Also, the rotor plate 12
In order to fix the rotor plate 12 itself when manufacturing the rotor 10 with an FG (in this embodiment,
(Four) holding holes 12b. In addition, FIG.
As can be seen from FIG. 2, which is a sectional view taken along the line II, the end portion (outer peripheral portion) of the rotor plate 12 is bent vertically downward to form the side wall 12c. As can be seen from FIG. 2, the cross section of the shaft hole 12a is formed in a convex shape.

The FG-equipped rotor 10 includes a plastic magnet 14.
2 is formed in a ring shape, and is provided on the outer surface of the side wall 12c of the rotor plate 12 by adhesion, as can be clearly seen from FIG.

The FG-equipped rotor 10 is attached to a VCR 20 as shown in FIG.
It is the figure which looked at from the bottom. Referring to FIG. 3, FG-equipped rotor 10 is connected to a rotor 22 b provided on rotating shaft 22 a of capstan motor 22 by a belt 24 such as a timing belt. Therefore, when the capstan motor 22 rotates, the FG-equipped rotor 10 also rotates. At this time, a magnetic sensor (not shown) provided near the outer periphery of the FG-equipped rotor 10
A change in the magnetic field due to the rotation of the motor is detected, and a pulse signal corresponding to the change is output to a control device (not shown) such as a system control microcomputer. The control device can detect the frequency of the input pulse signal and know the rotation speed of the capstan motor 22. Then, it is determined whether or not the rotation speed is normal, and a driving device (not shown) of the capstan motor 22 is controlled so as to rotate at an appropriate rotation speed.

In manufacturing (forming) the FG-equipped rotor 10 of this embodiment, first, a rotor plate 12 having a shape as shown in FIG. 4A is prepared in another step. The rotor plate 12 is formed by forming a shaft hole 12a and a plurality of pressing holes 12b at desired positions on an iron plate, and then bending the outer periphery of the shaft hole vertically to form a side wall 12c.

Next, as shown in FIG. 4B, upper and lower molds (upper mold 30 and lower mold 32) are arranged so as to sandwich rotor plate 12. Such upper and lower molds are prepared in advance to manufacture the rotor 10 with FG,
The upper die 30 is provided with one gate 30 a at a position facing the shaft hole 12 a of the rotor plate 12. The lower mold 32 has a protrusion (shaft pin) 32 inserted into the shaft hole 12a.
a and a projection (holding pin) 32b inserted into the holding hole 12b
Are provided.

Although not shown in the drawings, in this embodiment, four holes correspond to the holding holes 12b of the rotor plate 12.
One holding pin 32b is provided.

Therefore, when the shaft pin 32a is inserted into the shaft hole 12a and the holding pin 32b is inserted into the holding hole 12b, the rotor plate 12 is mounted on the lower die 32. As described above, since the rotor plate 12 is mounted on the lower mold 32, the rotor plate 12 does not rotate (rotate) in the horizontal direction during the manufacture of the rotor 10 with FG, and can be fixed in the mounted state. it can. And the lower mold 32
And the upper mold 30 are combined to form the cavity 34. As can be clearly understood from FIG. 4B, the cavity 34 is formed outside the side wall 12c of the rotor plate 12 and on the upper surface of the rotor plate 12.

Subsequently, using a hot runner (not shown), a melt of the plastic magnet 14 is injected from a gate 30a provided at the center of the upper mold 30 as shown in FIG. 34 (molded). At this time, the shaft hole 12a is
Since it is closed by 2a, the melt of the plastic magnet 14 does not flow into the shaft hole 12a. Similarly, since the holding hole 12b is closed by the holding pin 32b, the molten material of the plastic magnet 14 does not flow into the holding hole 12b.

As shown in FIG. 5A, the melt of the plastic magnet 14 flows radially on the upper surface of the rotor plate 12. Therefore, the time required for the melt of the plastic magnet 14 to reach the side wall 12 c is substantially uniform over the entire outer periphery of the rotor plate 12.

As shown in FIG. 5B, in the portion where the holding hole 12b is formed, the molten material of the plastic magnet 14 is caused to avoid the holding hole 12b by the surface tension, in other words, the holding hole 12b. Flows along the outer circumference of. For this reason, when the diameter of the holding hole 12b is increased, the side wall 1 between the melt of the plastic magnet 14 passing near the holding hole 12b and the melt of the plastic magnet 14 passing away from the holding hole 12b.
There is a difference in the time required to reach 2c, which causes a weld line. In order to avoid this, in this embodiment, the diameter of the holding hole 12b is formed as small as possible so that the molten material of the plastic magnet 14
The time required to reach c is made uniform.

However, if the diameter of the holding hole 12b is made small, the diameter of the holding pin 32b inserted therein must also be made small, and the holding pin 32b may be damaged. Therefore, in order not to damage the holding pin 32b,
When the diameter is relatively large, the diameter of the holding hole 12b needs to be relatively large.
In such a case, as shown in FIG. 5 (C), an oval holding hole 12b having a major axis in the same direction as the radial direction (radial direction) of the rotor plate 12 is formed so that the holding hole 12b is formed. What is necessary is just to prevent the flow of the melt of the plastic magnet 14 passing near 12b from being delayed.

When the melt of the plastic magnet 14 is filled in the cavity 34 and the injection of the melt is completed,
After the melt has hardened to some extent, the mold is released as shown in FIG. Unnecessary plastic magnets 14 existing (retaining) on the upper surface side of the rotor plate 12 are cut off using, for example, a cutting device (not shown), and as shown in FIG. It is formed.

Thus, in the manufacturing method of this embodiment,
A hot runner is used to inject the melt of the plastic magnet 14 to cut off the plastic magnet 14 staying on the upper surface side of the rotor plate 12, as shown in FIGS. 7A and 7B. Unlike the conventional manufacturing method described, a large amount of material (plastic magnet) staying in the runner is not wasted. That is, manufacturing costs can be reduced. Further, by reducing the gap between the upper die 30 and the upper surface of the rotor plate 12, useless plastic magnets 14 can be reduced. However, it is necessary to make the gap small enough not to hinder the flow of the melt of the plastic magnet 14.

According to this embodiment, 1 is formed on the upper die.
Since the melt of the plastic magnet is injected from one of the gates and the melt flows radially on the rotor plate, the time required for the melt to reach the side wall of the rotor plate can be made uniform over the entire outer periphery.
Therefore, no weld line is generated in the plastic magnet. Further, since the injection amount of the melt of the plastic magnet can be adjusted relatively easily, it can be easily manufactured.

In this embodiment, four holding holes 12b and four holding pins 32b are provided. However, the rotor plate 12 may be fixed by the holding holes 12b and the holding pins 32b. Since it is only necessary to restrict the horizontal rotation of the holding member 12, at least one holding hole 12b and at least one holding pin 32b may be provided.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing one embodiment of the present invention;

FIG. 2 is a sectional view of the rotor with FG shown in FIG. 1 embodiment.

FIG. 3 shows a V using the FG-equipped rotor shown in FIG. 1 embodiment.
FIG. 4 is an illustrative view showing one example of a CR;

FIG. 4 is an illustrative view showing one portion of a step in manufacturing the rotor with FG shown in FIG. 1 embodiment;

FIG. 5 is an illustrative view for explaining another portion of the step in the case of manufacturing the rotor with FG shown in FIG. 1 embodiment;

6 is an illustrative view for explaining another portion of the process in the case of manufacturing the rotor with the FG shown in the embodiment in FIG. 1;

FIG. 7 is an illustrative view for explaining a step in a case where a rotor with an FG is manufactured by a conventional manufacturing method;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... rotor with FG 12 ... rotor plate 14 ... plastic magnet 20 ... VCR 22 ... capstan motor 24 ... belt 30 ... upper mold 32 ... lower mold 34 ... cavity

Claims (4)

[Claims] 1. A method of manufacturing a rotor with an FG used for controlling rotation of a capstan motor provided in a VCR, comprising: a disk having a side wall on an outer periphery and having a shaft hole and at least one holding hole in the center. Preparing a rotor plate having a shape, preparing an upper die having one gate at a position facing the shaft hole, and having a shaft pin inserted into the shaft hole and at least one holding pin inserted into the holding hole; Prepare a lower mold, insert the shaft pin into the shaft hole, insert the holding pin into the holding hole, attach the rotor plate to the lower mold, and combine the lower mold and the upper mold. A cavity is formed outside the side wall of the rotor plate and on the upper surface side of the rotor plate, and a plastic magnet is formed from the gate of the upper die to the cavity. Injecting a melt, and said so as to ablate the plastic magnet on the upper surface of the rotor plate after the injection of the melt, the manufacturing method of the FG with the rotor. 2. A method of manufacturing a rotor with an FG used for controlling the rotation of a capstan motor provided in a VCR, comprising: a disk having a side wall on the outer periphery and having a shaft hole and at least one holding hole in the center. Preparing a rotor plate having a shape, preparing an upper die having one gate at a position facing the shaft hole, and having a shaft pin inserted into the shaft hole and at least one holding pin inserted into the holding hole; Prepare a lower mold, insert the shaft pin into the shaft hole, insert the holding pin into the holding hole, attach the rotor plate to the lower mold, and combine the lower mold and the upper mold. Thereby forming a cavity, and injecting a melt of a plastic magnet from the gate of the upper mold into the cavity. 3. The method according to claim 2, wherein the cavity is formed outside a side wall of the rotor plate and above the rotor plate, and the plastic magnet on an upper surface side of the rotor plate is cut off after the injection of the melt. Manufacturing method of rotor with FG. 4. The method for manufacturing a rotor with an FG according to claim 2, wherein said holding holes are formed in an elliptical shape having a major axis in a direction same as a radial direction of said rotor plate.