JP2004167915A - Mold for molding magnet rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To integrally mold a pin shape on a magnet for a rotor to which magnetic properties having been already given under a condition where a relative position to a position where the magnetic properties have been given is fitted to each other. <P>SOLUTION: A mold for molding a magnet rotor molds a shaft part 3 at the center of a cylindrical magnet 1 for the rotor to which the magnetic properties have been given for at least two poles in the circumferential direction, and also molds a pin-shaped part 4 for driving other members. The mold is provided with mold members 9 and 9' constituting a cavity for molding the shaft part 3 and the pin-shaped part 4, and magnets 8 and 8' at least one of which is arranged on the mold members and which position the magnet for the rotor in the rotating direction by attracting specified magnetic poles of the magnet for the rotor to which the magnetic properties have been given, and which fit positions in the rotating direction of the magnetic poles to which the magnetic properties have been given and a pin-shaped part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for manufacturing a motor, a magnet rotor for driving a shutter blade or an aperture blade of a camera or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a method of manufacturing a magnet rotor for driving a shutter blade and an aperture blade of a motor and a camera, for example, as disclosed in Japanese Patent Publication No. 58-36581, a magnet rotor is formed by using a cavity of an injection mold. When the shaft is formed by filling the remaining space with resin, the outer periphery of the magnet rotor is also filled with resin to prevent expansion damage of the magnet rotor due to resin pressure applied to the inner diameter of the magnet rotor during molding. There are known ways to prevent this. Further, a method has been used in which the clearance between the inner diameter of the cavity into which the magnet is inserted and the outer dimension of the inserted magnet is made as small as possible.
[0003]
In addition, as a method of matching a pin position for driving a shutter blade or an aperture blade of a camera or the like formed on a conventional magnet rotor with a magnetization angle of the magnet rotor, an Nd-Fe-B-based isotropic rare earth magnet is used. Was normal. A method has been used in which the pin portion is inserted into a mold for injection molding in a non-magnetized state, and the pin portion is formed, and magnetized based on the position of the pin in a later step.
[0004]
Alternatively, instead of integrating the pin portions by injection molding, a method is used in which the position of the magnet is determined by a jig, and a member having a separately formed pin shape is fixed by press-fitting or bonding.
[0005]
[Problems to be solved by the invention]
However, the method of press-fitting or bonding a member provided with a separately formed pin shape to the magnet causes problems such as cracking of the magnet at the time of press-fitting, insufficient rotary strength, and insufficient pull-out strength, and a problem in magnet positioning. There was also a problem in terms of assembling man-hours, as it took a lot of time to attach the components. In addition, the bonding improves the magnet cracking, rolling strength and detachment strength, but has many problems such as the occurrence of problems due to the adhesion of the adhesive to the shaft portion and the long curing time.
[0006]
In the method of inserting a non-magnetized Nd-Fe-B based isotropic rare earth magnet into an injection molding mold and shaping the pin shape for driving the shutter blades and aperture blades of a camera, etc., the pin shape is determined in a later process. Therefore, the number of man-hours required for magnetization was long. In addition, since the material of the magnet is limited, the magnetic properties are low, and there is a limit to miniaturization.
[0007]
Further, in the conventional method in which the resin is wrapped around the outer periphery of the magnet rotor in order to prevent cracking of the magnet rotor inserted into the mold, it is necessary to remove the resin at the outer periphery in a later process, which increases costs. .
[0008]
Further, if the clearance between the inner diameter of the mold cavity and the outer dimension of the magnet rotor is made as small as possible, it becomes difficult to insert the magnet rotor into the cavity. Also, cracking of the magnet cannot be reliably prevented. If the injection pressure is lowered to prevent cracking, there is a problem that a short circuit occurs and a molding material to be used is limited.
[0009]
Accordingly, the present invention has been made in view of the above-described problem, and an object of the present invention is to integrally form a pin shape with a magnetized rotor magnet in a state where a relative position to a magnetized position is matched. Is to do so.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, a molding die for a magnet rotor according to the present invention includes a shaft portion centered on a cylindrical rotor magnet magnetized in two or more poles in a circumferential direction. And a molding die for a magnet rotor for molding a pin-shaped portion for driving another member, and forming a cavity for molding the shaft portion and the pin-shaped portion. A mold member, at least one of which is disposed on the mold member, attracts a predetermined magnetic pole magnetized by the rotor magnet, thereby positioning the rotor magnet in the rotational direction, thereby performing the magnetizing. And a magnet for adjusting the position of the magnetic pole and the pin-shaped portion in the rotational direction.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described.
[0012]
First, an outline of the present embodiment will be described.
[0013]
The mold for manufacturing the magnet rotor according to the present embodiment inserts a cylindrical sintered magnet or a bond magnet magnetized to two or more poles in a radial direction into a cavity in an injection mold, and has an inner diameter of the magnet. Filling the part with resin, the shaft part further shutter blades such as a camera, a manufacturing die of a magnet rotor for integrally forming a pin shape for driving the diaphragm blades, wherein the rotor magnet Mold processing in which the center of the mold cavity into which the rotor magnet is inserted and the pin shape that drives the blades are processed so that the positional relationship between the magnetization direction and the pin shape driving the aperture blades and the like is at a predetermined angular position. The magnets for the rotor magnetized on the line at a predetermined angle toward the center of the cavity into which the magnet for the rotor is inserted, based on the line connecting the Placing two or more at a position opposite the angular positioning magnet which is magnetized to the poles around the one location or cavity center. At the same time, the cavity is made of a non-magnetic material divided into two or more pieces which can be moved in the radial direction of the rotor magnet, so that the rotor magnet can be easily inserted. By using a non-magnetic material for the mold member in contact with the rotor, the magnetized rotor magnet is prevented from being attracted to the mold.
[0014]
Further, in a state where the movable piece in the outer diameter direction of the rotor magnet constituting the cavity is fully closed in the inner diameter direction, the outer dimension value of the rotor magnet is partially or entirely set to an upper limit value. The lower limit was set so that a cylindrical magnet rotor inserted in advance was subjected to a load in the compression direction by a compression tester, and the lower limit was set to the maximum value within elastic deformation where cracks did not occur. As a result, the magnet tends to expand in the outer diameter direction due to the injection pressure, but is limited by the inner diameter of the mold, so that the magnet does not break due to the force in the expansion direction.
[0015]
Hereinafter, the present embodiment will be specifically described.
[0016]
FIG. 1 is a sectional view of a product formed by a mold according to one embodiment of the present invention. Reference numeral 1 denotes a rotor magnet magnetized in the lateral direction. Reference numerals 2 and 3 denote rotating shaft portions formed of resin. Reference numeral 4 denotes a blade drive pin for driving a shutter blade or an aperture blade of the camera. Reference numeral 5 denotes a retaining shape portion for preventing the molded shaft portion from coming off the magnet 1. It is necessary that the angular position of the blade drive pin 4 is accurately formed with respect to the magnetization direction of the magnet 1.
[0017]
FIG. 2 is a plan view showing the cavity of the mold according to the embodiment.
[0018]
In FIG. 2, the cavity 6 into which the rotor magnet 1 is inserted is constituted by non-magnetic slide pieces 9 and 9 'which can move in the radial direction of the magnet 1. FIG. 2 shows a state where the slide pieces 9, 9 'are open. In this state, since the outer dimensions of the rotor magnet 1 and a sufficient clearance are secured, the magnet 1 can be easily inserted into the cavity 6. FIG. 2 shows the polar directions N and S indicating the magnetized state of the magnet 1. In order to generate a force for rotating the magnet 1 to a predetermined angle by using the attractive force of the magnet 1, the non-magnetic slide pieces 9, 9 ′ are magnetized for angular positioning magnets 8, 8 magnetized in the longitudinal direction. 'Has been installed. The magnets 8, 8 'are on a line having a predetermined angle passing through the center of the cavity 6 with reference to a line connecting the center of the cavity 6 into which the magnet 1 is inserted and the center position of the molding portion for molding the blade drive pin. The magnet 6 is provided at a symmetric position about the center of the cavity 6 at a position where a force sufficient to rotate the magnet 1 to a predetermined angle acts.
[0019]
Further, by making the slide piece non-magnetic, it is possible to prevent the slide piece 9, 9 'from being attracted by the attraction force of the magnet 1, and to smoothly move to a predetermined angular position. FIG. 3 shows a state in which the slide pieces 9, 9 'are fully closed. The inner diameter of the cavity in the fully closed state is determined by setting the outer diameter of the magnet 1 as a maximum value and within the range of the elastic deformation in the compression direction. Thereby, it is possible to particularly prevent magnet cracking due to expansion in the outer diameter direction due to the injection pressure.
[0020]
FIG. 4 shows a sectional view of the mold. The molten resin injected with the mold closed is passed through the secondary spool 11 provided on the fixed mold plate 13 via the spool runner portion, and is injected into the cavity through the gate 12. Reference numeral 14 denotes a movable-side template. Reference numeral 16 denotes a receiving piece, which has a shaft shape of the magnet 1 and a through hole for operating an ejector pin 15 for projecting a molded product. At this time, the receiving piece 16 also needs to be made of a non-magnetic material. This is to prevent the magnetic force of the magnet 1 from attracting and hindering the operation for angle positioning.
[0021]
(Other embodiments)
FIG. 5 is a diagram showing another embodiment. The angle positioning magnet 8 is formed as one piece. As described above, the position of the magnet 1 can be defined even with one angle positioning magnet.
[0022]
FIG. 6 is a view showing a conventional example, in which a member having a shaft shape separately formed is press-fitted into the magnet 18.
[0023]
No press-fitting prevention shape. Also, a method of performing magnetization based on a pin-shaped position of a press-fitted member is often used.
[0024]
As described above, by arranging the magnet having the function of determining the angular position of the magnet 1 in the mold, it is possible to use a large number of magnets simultaneously magnetized with an air-core coil, etc. Thus, the number of magnetization steps can be reduced.
[0025]
Further, the angle of the magnet 1 can be accurately determined in the mold, and the angular position accuracy with respect to the formed blade drive pin can be greatly improved. Also, unlike the press-fitting, the shaft portion and the pin portion are formed by molding, so that the rotary strength and the punching strength can be greatly improved.
[0026]
Also, for the crack of the magnet, the inside diameter of the cavity is set within the elastic deformation of the magnet to prevent the crack of the magnet, and the slide method allows sufficient clearance with the cavity when inserting the magnet. Since the magnetism is easy and the clearance is large, the magnet can be easily moved to a predetermined position, and the angle accuracy can be improved.
[0027]
【The invention's effect】
As described above, according to the present invention, a pin shape can be integrally formed with a magnetized rotor magnet in a state where the relative position to the magnetized position is matched.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a molded product according to one embodiment of the present invention, in which a magnet, a resin shaft, and a blade drive pin are integrated.
FIG. 2 is a view showing a state in which a rotor magnet magnetized in a state where a slide piece is opened is inserted in a mold according to an embodiment of the present invention.
FIG. 3 is a view showing a state where a slide piece is fully closed in the mold shown in FIG. 2;
FIG. 4 is a sectional view of the mold shown in FIG. 2;
FIG. 5 is a diagram showing another embodiment.
FIG. 6 is a cross-sectional view of a conventional magnet rotor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotor magnet 2 Molded shaft part 3 Molded shaft part 4 Blade drive pin part 5 Retaining shape 6 Cavity 7 Magnetized state 8 Angle positioning magnet 9 Slide piece 10 Part of cavity shape 11 Secondary spool 12 Gate 13 Fixed-side template 14 Movable-side template 15 Ejector pin 16 Receiving piece 17 Member formed as a single item 18 Press-fit magnet

Claims (1)

Molding metal for a magnet rotor for molding a shaft at the center of a cylindrical rotor magnet magnetized in two or more poles in the circumferential direction and for molding a pin-shaped part for driving other members Type,
A mold member constituting a cavity for molding the shaft portion and the pin-shaped portion,
At least one of the magnet members is arranged on the mold member, and a predetermined magnetic pole magnetized for the rotor magnet is attracted to thereby position the rotor magnet in the rotational direction. A magnet for molding a magnet rotor, comprising: a magnet for adjusting a position in a rotational direction with respect to a shape portion.

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