JP2006174584A - Motor magnet and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of integrating a magnet with a driving pin without preparing a joint portion at a magnet center portion which was conventionally used in insert molding. <P>SOLUTION: This motor magnet 10 comprises a resin joint type permanent magnet 11 made of a molded body of a composition in which resin for a binder is mixed in magnetic powder, and a resin member 12 integrated with the permanent magnet 11. A copper plating layer 11b is formed at a surface of the permanent magnet 11, and a coating 11c made of triazine thiol derivative is formed on the copper plating layer 11b. The permanent magnet 11 covered with the triazine thiol derivative coating 11c is attached at a die, and the insert molding is performed by using themoplastic resin to form the resin member 12 integrally with the permanent magnet 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor magnet used for a rotor of a small motor such as an iris motor or a flat motor, and a manufacturing method thereof. An iris motor or a flat motor is used as a power source for a shutter incorporated in a mobile device or a shutter incorporated in a digital camera, for example.

As a motor for opening and closing the shutter blades and the diaphragm blades, a small and inexpensive motor that is generally called an iris motor or a moving magnet type motor is known. The rotor of this motor is composed of a two-pole permanent magnet, and a coil is wound on the stator side so as to cover the bearing portion of the rotor. Then, the rotor is rotated forward and backward by changing the energization direction of the coil. Although this type of motor is small and can be manufactured inexpensively, it is difficult to obtain a large driving force like a pulse motor. Therefore, the drive pin is usually configured integrally with a permanent magnet, and the drive pin operates within a predetermined operating angle. The shutter blades and the diaphragm blades are operated directly or through a few parts. Specific examples of the motor magnet in which the drive pin and the permanent magnet are integrally configured as described above are described in Patent Documents 1 to 4 below. Patent Documents 5 and 6 are not related to the motor magnet, but are listed as related techniques for surface treatment.
JP 09-152645 A JP 2002-050058 A Japanese Patent Laid-Open No. 06-1054889 Japanese Patent Application Laid-Open No. 07-131957 Japanese Patent Laid-Open No. 10-237047 JP 2000-160392 A

  The configuration of the rotor of the motor disclosed in Patent Document 1 is shown in FIG. (A) is a top view of the rotor manufactured integrally with the drive pin, (b) is a cross-sectional view of (a), and (c) is the rotor shown in (a) and (b). It is a flowchart in the case of manufacturing. As a general permanent magnet used for a rotor of this type of motor, an Nd-Fe-B (neodium ferrite bond) type magnetic powder is blended with an epoxy resin and molded by a press machine. Used. As shown in the drawing, the permanent magnet 21 is formed in a substantially cylindrical shape, and the permanent magnet 21 is inserted into a mold, and the resin 22 is injected and solidified in the mold to drive the shaft portions 22b and 22c. The pin 22 a is formed integrally with the permanent magnet 21.

  Patent Document 2 discloses an optical pickup motor that uses a thermosetting adhesive for joining an elastic member, a magnet, and a yoke. Patent Document 3 discloses a rotor magnet fixing method characterized in that a groove is provided in a joint surface between a magnet and an intervening part and fixed with an adhesive. Patent Document 4 discloses a resin in which a permanent magnet portion made of magnetic powder and a thermosetting resin and a nonmagnetic material portion made of a nonmagnetic powder and a thermosetting resin are integrally formed adjacent to each other. A combined magnet rotor is disclosed.

  The motor magnet disclosed in Patent Literature 1 is filled with a resin material in the center of a cylindrical magnet. A resin layer was provided at the center of the magnet, and a motor magnet was obtained by insert molding. However, since the center portion of this structure is filled with resin, the effective volume of the magnet is reduced. Therefore, it is not preferable for obtaining a high magnetic force. Iris motors are advantageous in terms of downsizing and cost reduction compared to pulse motors, but they are difficult in terms of driving force. Accordingly, the magnetic flux density of the rotor is preferably as large as possible. However, when a cylindrical magnet is used as in the cited document 1, there is a problem that a high magnetic force cannot be obtained.

  In each of the motor magnets disclosed in Patent Documents 2 and 3, permanent magnets and intervening parts such as drive pins are joined together with an adhesive. However, due to the downsizing of parts, it has become difficult to manufacture products with the conventionally applied adhesive coating method, and there is a problem that the yield is also deteriorated.

  Patent Document 5 discloses a triazine thiol derivative and a surface treatment method for an article using the same. Patent Document 6 discloses a plating product of magnesium and its alloy by a triazine thiol derivative and a composite of these and an organic polymer material. However, none of the surface treatment methods described in Patent Documents 5 and 6 are related to the motor magnet.

  In view of the above-described problems of the conventional technology, the present invention provides a motor magnet in which a magnet and a drive pin are integrated, and a method for manufacturing the same, without providing a connecting portion at the center of a magnet that has been implemented by conventional insert molding. Accordingly, it is an object to reduce the size of the motor magnet. In order to achieve this purpose, the following measures were taken. That is, the present invention relates to a motor magnet composed of a resin-bonded permanent magnet composed of a molded product of a magnetic powder and a binder resin, and a resin member integrated with the permanent magnet. A copper plating layer is formed on the surface, and a film made of a triazine thiol derivative is further formed on the copper plating layer, and the resin member is coated with the triazine thiol derivative film. Is formed integrally with the permanent magnet by performing insert molding using a thermoplastic resin.

  Preferably, the permanent magnet is provided with a rust preventive coating made of nickel plating as a base of the copper plating layer. The permanent magnet is formed by electrodeposition of a film of the triazine thiol derivative. The resin member is insert-molded with a thermoplastic resin selected from acrylic resin, polycarbonate resin, and polybutylene terephthalate resin.

  The present invention also provides a method for producing a motor magnet comprising a resin-bonded permanent magnet comprising a molded product of a composition in which a binder resin is blended with magnetic powder, and a resin member integrated with the permanent magnet. A plating process for forming a copper plating layer on the surface of the permanent magnet, a surface treatment process for forming a film made of a triazine thiol derivative on the copper plating layer, and the permanent magnet coated with the triazine thiol derivative film And a molding step of forming the resin member integrally with the permanent magnet by performing insert molding using a thermoplastic resin.

  Preferably, prior to the plating step, a pretreatment step of applying a rust preventive coating made of nickel plating to the surface of the permanent magnet is included. In the surface treatment step, a film of the triazine thiol derivative is formed on the copper plating layer by electrodeposition. In the molding step, a thermoplastic resin selected from acrylic resin, polycarbonate resin, and polybutylene terephthalate resin is used.

  A permanent magnet made of a molded body of a composition in which a binder resin is blended with magnetic powder is usually nickel-plated on the surface as a rust-proof coating. However, the surface of the nickel-plated permanent magnet as a rust preventive coating and the thermoplastic resin used to mold the resin member have weak adhesion even if they are simply integrated in the mold, and will peel off immediately. . Therefore, in the present invention, a film of a triazine thiol derivative having a strong binding force to both the metal material and the thermoplastic resin material is previously formed on the surface of the permanent magnet. By integrating the permanent magnet coated with the triazine thiol derivative film in this way with the resin member in the mold, a good bonding strength between the permanent magnet and the resin member can be obtained through the triazine thiol derivative film, and a small size can be obtained. You can get a motor magnet. The triazine thiol derivative has a particularly strong binding force to copper among metal materials, and has a relatively weak binding force to nickel. Therefore, in the present invention, the surface of the permanent magnet is previously plated with copper before the triazine thiol derivative film is formed. Of course, it is also possible to apply nickel plating to the base of the copper plating in consideration of rust prevention of the permanent magnet.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic perspective view showing a motor magnet and a manufacturing method thereof according to the present invention. The motor magnet 10 basically includes a permanent magnet 11 and a resin member 12. The permanent magnet 11 is a so-called resin-bonded type, and is formed of a molded body of a composition in which a magnetic resin is mixed with a binder resin. In the illustrated embodiment, the permanent magnet 11 is previously formed into a cylindrical shape. The permanent magnet 11 is, for example, Nd—Fe—B sintered or a resin-bonded type of Nd—Fe—B and Sm—Fe—N. Characteristically, the permanent magnet 11 has a copper plating layer 11b formed on the surface thereof, and a film 11c made of a triazine thiol derivative is further formed on the copper plating layer 11b. The figure also shows the general structural formula of the triazine thiol derivative. On the other hand, the resin member 12 is formed integrally with the permanent magnet 11 by loading the permanent magnet 11 covered with the triazine thiol derivative film 11c into a mold and performing insert molding using a thermoplastic resin. In the illustrated example, the resin member 12 is an injection-molded member including a bearing portion 12a, a drive pin 12c, and an arm 12d that couples both.

  In the present embodiment, the permanent magnet 11 is preliminarily provided with a rust preventive coating 11a made of nickel plating as a base of the copper plating layer 11b. In the present embodiment, the triazine thiol derivative film 11c is formed by electrodeposition. The resin member 12 is insert-molded with a thermoplastic resin selected from an acrylic resin, a polycarbonate resin, and a polybutylene terephthalate resin.

  In order to manufacture the motor magnet 10 having such a structure, in the present invention, a plating process, a surface treatment process, and a molding process are performed. In the plating step, a copper plating layer 11b is formed on the surface of the permanent magnet 11 by, for example, electroless plating. Note that the present invention is not limited to this, and electrolytic plating may be used to form dense metallic copper at high speed. Thereafter, in the surface treatment step, a triazine thiol derivative film 11c is formed on the copper plating layer 11b by, for example, electrodeposition. In addition, this invention is not restricted to this, You may form the triazine thiol derivative membrane | film | coat 11c by a normal immersion process. Specifically, the permanent magnet 11 after copper plating is immersed in an aqueous solution of a triazine thiol derivative. Subsequently, in the molding step, the permanent magnet 11 covered with the triazine thiol derivative film 11c is loaded into a mold, and insert molding is performed using a thermoplastic resin, thereby forming the resin member 12 integrally with the permanent magnet 11. .

  In this embodiment, the pretreatment process is performed prior to the copper plating process. In this pretreatment step, the surface of the permanent magnet 11 is provided with a rust-proof coat 11a made of nickel plating. In the copper plating step, the copper plating layer 11b is electrolytically or electrolessly plated on the anticorrosive coating 11a.

  Usually, the rust preventive coating 11a made of nickel plating or the like and the thermoplastic resin for molding are weakly bonded even if they are simply integrated in the mold, and peel off immediately. Therefore, in the present invention, the surface of the permanent magnet 11 is preliminarily applied with the triazine thiol derivative film 11c having a strong binding force to both the metal film and the thermoplastic resin material, and this is integrated with the thermoplastic resin in the mold. Thus, good bonding strength can be obtained, and a small motor magnet 10 can be produced. However, the triazine thiol derivative film 11c has a particularly strong bonding force with respect to copper among metal materials, but does not exhibit such a strong bonding force with respect to nickel. Therefore, in the present invention, the copper plating layer 11b is formed on the rust preventive coating 11a made of nickel plating, and the triazine thiol derivative film 11c is formed thereon. Thus, by interposing the copper plating layer 11b and the triazine thiol derivative film 11c, the binding force between the permanent magnet 11 and the resin member 12 is increased as a result.

In the general formula of the triazine thiol derivative shown in FIG. 1, R is —OR ′, —SR ′, —NHR ′, —N (R ′) ₂ . Here, R ′ is an alkyl group, an alkenyl group, a phenyl group, a phenylalkyl group, an alkylphenyl group or a cycloalkyl group. In the general formula shown in FIG. 1, M is H, Na, Li, K, 1 / 2Ba, 1 / 2Ca, aliphatic primary, secondary and tertiary amines, quaternary ammonium salts, and the like.

  The case where the triazine thiol derivative represented by the general formula in FIG. 1 is formed by electrodeposition will be described. First, an aqueous solution of a triazine thiol derivative film or a solution using an organic solvent as a solvent is prepared as an electrodeposition solution. The organic solvent can be selected from methyl alcohol, isopropyl alcohol, ethyl alcohol, acetone, toluene, ethyl cellosolve, dimethylformaldehyde, tetrahydrofuran, methyl ethyl ketone, benzene, ethyl acetate, and the like.

A copper-plated permanent magnet is immersed in this triazine thiol derivative electrodeposition solution to make it an anode. On the other hand, a platinum plate, a titanium plate or a carbon plate is immersed in the electrodeposition solution as the cathode. A current of 0.1 mA / dm ² to 10 A / dm ² is applied between the anode and the cathode at 20 V or less for 0.1 seconds to 10 minutes. As a result, the triazine thiol derivative film 11 c is formed on the surface of the copper plating layer of the permanent magnet 11. The temperature of the electrodeposition solution is kept at room temperature or about 80 ° C.

  Triazine thiol derivatives are particularly compatible with copper. In the case of copper, a relatively thick film can be formed even by a normal dipping process. Therefore, in some cases, a triazine thiol derivative film may be formed on the copper plating layer by dipping instead of electrodeposition.

  Electroless nickel plating is applied to a cylindrical Nd—Fe—B sintered magnet having a diameter of 2.75 mm and a height of 2.1 mm, and further copper plating is applied thereon to a thickness of 2.5 μm. A triazine thiol derivative film was formed on the surface by electrodeposition. Specifically, 1,3,5-triazine-2,4,6-trithiol · triethanolamine (F · TEA), which is an amine salt of triazine thiol, is dissolved in water at a concentration of 1% to form an electrodeposition tank. It was thrown into. The treatment temperature was kept at 20 ° C., and a film was formed by immersing a permanent magnet plated with copper in advance in an electrodeposition bath. In addition, instead of the amine salt of triazine thiol, 1,3,5-triazine-2,4,6-trithiol monosodium (FN) which is an alkali salt may be used. The sample permanent magnet with the triazine thiol derivative film formed in this manner is loaded into a mold having a mold temperature of 90 ° C., and a polycarbonate resin having a resin temperature of 300 ° C. is molded by injection molding. A resin member 12) was obtained. When the bonding strength between the resin member 12 and the permanent magnet 11 was measured, it did not peel off even at a load of 200 g.

  As Comparative Example 1, a motor magnet was manufactured by performing the same injection molding as Example 1 with the triazine thiol derivative film omitted. The bonding strength between the resin member and the permanent magnet in this sample was 10 to 50 g, and both peeled easily.

  As Comparative Example 2, instead of the surface treatment step for forming the triazine thiol derivative film, a corona discharge treatment was adopted, and the surface of the permanent magnet was subjected to a corona discharge treatment to enhance the adhesion. Using a permanent magnet subjected to corona discharge treatment, injection molding was performed in the same manner as in the example to produce a motor magnet. When the bonding strength of the obtained sample was measured, it peeled easily in the range of 10 to 100 g.

  As Comparative Example 3, the bonded portion of the permanent magnet was irradiated with a laser to roughen the surface and increase the adhesive strength. A permanent magnet subjected to laser irradiation treatment was loaded into a mold, and injection molding was performed in the same manner as in the example to prepare a motor magnet. When the bonding strength of the obtained samples was measured, there were many samples that varied in the range of 10 to 200 g and easily peeled off.

  Finally, an example of using the motor magnet manufactured according to the present invention will be described. In this use example, a motor magnet is incorporated in an iris motor, and this is applied to a shutter opening / closing mechanism. FIG. 2 is a plan view of the shutter, and FIG. 3 is a cross-sectional view cut so that the overlapping relationship of the components in FIG. 2 can be easily understood. First, the configuration of this usage example will be described with reference to FIGS. 2 and 3. The synthetic resin shutter base plate 1 has an opening 1a. The presser plate 2 has substantially the same outer shape as the shutter base plate 1 in plan view, and an opening 2a having substantially the same shape is formed at the center so as to overlap the opening 1a. The presser plate 2 is attached to the shutter base plate 1 with screws 3 and 4 and forms a blade chamber between them. The shutter blades 5 and 6 are pivotally attached to the shaft portions 1b and 1c of the shutter base plate 1 in the blade chamber, respectively.

  The cover plate 7 is attached to the shutter base plate 1 with screws 8 and 9, and forms a motor chamber between them. The motor magnet 10 constituting the rotor is composed of a permanent magnet 11 and a resin member 12 and is rotatably attached to the shutter base plate 1 and the cover plate 7. As described above, the resin member 12 is formed integrally with the permanent magnet 11 by injection molding. The resin member 12 is divided into a drive pin 12a, bearing portions 12b and 12c, and the like. The drive pin 12a passes through a hole 1d formed in an arc shape in the shutter base plate 1 and is fitted in a well-known long hole formed in the shutter blades 5 and 6 although not clearly shown.

  The motor iron core 13 has a substantially U-shape with two legs, and a bobbin 15 around which a coil 14 is wound is fitted into one leg, and a slightly arc-shaped hole is formed at the root. 13a is formed. The iron core 13 is fixed between the shutter base plate 1 and the cover plate 7 with screws 8, but there is a sufficient gap between the inner wall of the hole 13a and the screw diameter of the screw 8. By slightly tightening 8, the tip position of the leg portion of the iron core 13 can be adjusted with respect to the motor magnet 10.

  The operation of this embodiment will be described with reference to FIGS. FIG. 2 shows an initial position of the shutter in which the shutter blades 5 and 6 close the openings 1a and 2a. Since the permanent magnet 11 is magnetized in two poles with the line connecting the rotating shaft 12b and the drive pin 12a as a boundary in FIG. 2, the motor magnet 10 is imparted with left-handedness at this initial position. The left-handed rotation is blocked by the drive pin 12a coming into contact with the edge of the hole 1d, thereby preventing an unexpected opening / closing operation due to vibration or the like. When the coil 14 is energized along with the shutter release, the motor magnet 10 rotates clockwise and the shutter blades 5 and 6 are opened by the drive pin 12a. When the coil 14 is energized in the reverse direction after a predetermined time, the motor magnet (rotor) 10 rotates counterclockwise, and the shutter blades 5 and 6 are closed. And it returns to an initial state by interrupting energization.

It is a typical partially broken perspective view which shows the motor magnet which concerns on this invention, and its manufacturing method. It is a typical top view which shows the usage example of the motor magnet shown in FIG. It is typical sectional drawing which shows the usage example of the motor magnet shown in FIG. It is a schematic diagram which shows the conventional motor magnet and its manufacturing method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Motor magnet, 11 ... Permanent magnet, 11a ... Antirust coating, 11b ... Copper plating layer, 11c ... Triazine thiol derivative film, 12 ... Resin member, 12a ... Shaft, 12c ... Drive pin, 12d ... Arm

Claims (8)

In a motor magnet composed of a resin-bonded permanent magnet composed of a molded product of a composition in which a binder resin is blended with magnetic powder, and a resin member integrated with the permanent magnet,
The permanent magnet has a copper plating layer formed on the surface, and a film made of a triazine thiol derivative is further formed on the copper plating layer.
The resin member is formed integrally with the permanent magnet by loading the permanent magnet coated with the triazine thiol derivative film into a mold and performing insert molding using a thermoplastic resin. Motor magnet.   2. The motor magnet according to claim 1, wherein the permanent magnet is provided with a rust preventive coating made of nickel plating as a base of the copper plating layer.   2. The method of manufacturing a motor magnet according to claim 1, wherein the permanent magnet has a film of the triazine thiol derivative formed by electrodeposition.   The motor magnet according to claim 1, wherein the resin member is insert-molded with a thermoplastic resin selected from an acrylic resin, a polycarbonate resin, and a polybutylene terephthalate resin. In a method of manufacturing a motor magnet comprising a resin-bonded permanent magnet composed of a molded product of a composition in which a binder resin is blended with magnetic powder, and a resin member integrated with the permanent magnet,
A plating step of forming a copper plating layer on the surface of the permanent magnet;
A surface treatment step of forming a film comprising a triazine thiol derivative on the copper plating layer;
A molding step in which the permanent magnet coated with the triazine thiol derivative film is loaded into a mold, insert molding is performed using a thermoplastic resin, and the resin member is formed integrally with the permanent magnet. A method for manufacturing a motor magnet.   6. The method of manufacturing a motor magnet according to claim 5, further comprising a pretreatment step of applying a rust preventive coating made of nickel plating to the surface of the permanent magnet prior to the plating step.   6. The method of manufacturing a motor magnet according to claim 5, wherein in the surface treatment step, a film of a triazine thiol derivative is formed on the copper plating layer by electrodeposition.   6. The method of manufacturing a motor magnet according to claim 5, wherein the molding step uses a thermoplastic resin selected from an acrylic resin, a polycarbonate resin, and a polybutylene terephthalate resin.

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