JPH04250013A - Mold for anisotropic resin magnet - Google Patents

Abstract

PURPOSE:To secure density of residual magnetic flux by a ferromagnetic powder material, by a method wherein a sprue bushing or various spacers are arranged respec tively on a movable mold side and stationary mold side and an axial magnetic field to be applied to the movable mold in a moving direction is made equilibrium magnetic field acting upon a cavity. CONSTITUTION:A mixed molten material of a magnetic powdery material and resin material is introduced into cavity C comprised of a nonmagnetic substance and a magnetic field is acted upon the cavity C, through which the magnetic powdery material is oriented and an anisotropic resin magnet is formed. In this case, a sprue bushing 21 which is provided on a stationary mold side and comprised of the magnetic substance, a central spacer 31 which is provided on a movable mold side and comprised of the magnetic substance, an outer spacer 33 which is provided on the movable mold side and comprised of the magnetic substance and a spacer 35 which is provided on a stationary mold side and comprised of the magnetic substance are arranged respectively. Then an axial magnetic field to be applied to the movable mold in a moving direction is made an equilibilium magnetic field acting upon the cavity C. With this construction, the magnetic powdery material is oriented and an anisotropic resin magnet is formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for forming an anisotropic resin magnet, and more particularly to a mold for forming an anisotropic resin magnet for forming an anisotropic resin magnet with excellent magnetic properties.

0002

[Prior Art] Various methods have been used to manufacture rotor parts etc. in which a functional member and a cylindrical magnet are integrally provided, but the representative method is to manufacture isotropic magnets in advance. However, a method is known in which a functional member made of resin is integrally formed by insert formation.

More specifically, after a cylindrical isotropic sintered magnet is set in an injection mold, a synthetic resin such as polyacetal resin with excellent mechanical properties is injected into the cavity to integrally form a functional component. do. Thereafter, in the next step, the outer peripheral surface of the isotropic sintered magnet is magnetized with multiple poles to obtain a finished product. However, when manufacturing by insert formation in this way, it is difficult to ensure the relative positional accuracy of the functional component made of resin and the polarization position that is multi-poled magnetized in the next process. In order to match the values, a magnetized yoke must be placed in the mold, but this is difficult to achieve due to the limitations of the mold structure.

Furthermore, when manufacturing by insert molding, cracking of the sintered magnet after injection molding becomes a problem. In order to prevent the occurrence of this cracking, it is necessary to lower the injection pressure of the molten resin or to make special arrangements for the injection mold itself, but if this is done, the dimensions of the functional component formed with resin will not be stable. Therefore, the occurrence of dimensional variations cannot be avoided. Therefore, by integrally manufacturing a functional member and a cylindrical magnet using an anisotropic resin magnet, it is possible to manufacture rotor parts etc. that have superior magnetic properties than those manufactured using an isotropic sintered magnet. is proposed.

This anisotropic resin magnet is produced by injecting a mixture of heated molten ferromagnetic powder and synthetic resin into a magnetic field injection mold into a cavity to which a magnetic field is applied, and magnetizing the clamping powder. The easy axis is oriented in a certain direction and magnetized in the next step. FIG. 5 is an external perspective view of an integrated product consisting of an anisotropic resin magnet and a resin functional member. In this figure, the rotor component 1 has a cylindrical main body with anisotropic pole parts 2 and 3.
is polarized and magnetized in half around the central shaft portion 4. An arm support portion 6a is integrally formed from the side surface of this anisotropic pole portion 2, and an arm portion 6 is also formed. Also,
A protrusion 5 is integrally formed on the lower surface of the anisotropic pole portion 3 .

When the rotor component 1 is integrally formed in this manner, it must be formed so that the line connecting the arm portion 6 and the central shaft portion 4 and the magnetization direction of the anisotropic pole portion 2 are exactly perpendicular to each other. There may be cases where this is not the case. FIG. 6 is a sectional view of a main part of a conventional magnetic field molding die for manufacturing the anisotropic resin magnet integral product shown in FIG. In this figure, the magnetic field generating means of the magnetic field forming mold is not shown, but the magnetic field forming mold is composed of a fixed mold and a movable mold that are separated from the parting surface P to take out the molded product. .

This fixed mold is constructed by fixing a fixed side mounting plate 11 having a resin introduction part and a fixed mold plate 12 using bolts 38. In addition to forming a gate G serving as a flow path for a certain resin, a spool bush 21 made of a magnetic material with a high magnetic saturation density and a fixed piece 36 formed with a runner R, which will be shown cross-hatched hereinafter, are incorporated.

Next, the movable mold has a movable mold plate 13 and a receiving plate 14.
and a spacer block 17, and a movable inserting piece 39 is incorporated into the movable mold plate 13. This movable entry piece 39 has a guide hole that guides the ejector pin 34 that pushes out the product formed in the cavity C in an inserted state, and a guide hole that guides the ejector pin 34 that pushes out the under part of the gate G in the inserted state. is drilled.

Further, on the outer peripheral surface of the movable inserting piece 39, there is an outer spacer 3 made of a magnetic material shown cross-hatched.
3 is included. Furthermore, a center spacer 31 made of a magnetic material and shown cross-hatched is incorporated in the center of the movable template 13.
A cavity block 32 having a cavity C formed therein is provided at a position sandwiched between the outer spacer 33 and the outer spacer 33 described above.

When a magnetic field is applied using the magnetic field molding mold having the above configuration, the spool bush 2 made of a magnetic material is
1, the center spacer 31, and the outer spacer 33 form a magnetic circuit, so that an anisotropic resin magnet can be formed within the cavity C. FIG. 7 is a computer magnetic field analysis diagram of the conventional magnetic field forming mold shown in FIG. In this figure,
When an axial magnetic field is generated in the magnetic field molding die in the axial direction, the lines of magnetic force H transmitted through the spool bush 21 and the center spacer 31 are transmitted to the outer spacer 33 as shown. The cavity C is provided between the center spacer 31 and the outer spacer 33 as described above, but according to computer magnetic field analysis, the lines of magnetic force H propagate slightly obliquely from the end 31a of the center spacer 31 to the end 33a of the outer spacer 33. , the remaining lines of magnetic force H also become so-called wetting magnetic flux that propagates in an oblique direction.

[0011]

[Problems to be Solved by the Invention] However, when a magnetic field is applied in the axial direction along the moving direction of the movable mold in the conventional magnetic field forming mold shown in FIGS. , Cavity C
As a result of the disturbance of the parallel magnetic field between the ends 33a and 31a that acts on the anisotropic resin magnet, the anisotropy rate of the ferromagnetic powder decreases, which could not be achieved originally with the ferromagnetic powder. There was a problem that the desired residual magnetic flux density could not be secured. Furthermore, when the surface residual magnetic flux density was measured after manufacturing with this magnetic field forming mold, considerable distortion was observed at the peaks and valleys of the approximately sinusoidal waveform, and it was found that there was variation in the bipolar magnetization.

Furthermore, there is a problem in that it is difficult to ensure the relative positional relationship between the position where the functional member is provided and the direction of magnetization of the resin magnet. Therefore, the molding die for anisotropic resin magnets of the present invention was created in view of the above-mentioned problems, and its purpose was originally achieved by using ferromagnetic powder in molding anisotropic resin magnets. An object of the present invention is to provide a mold for forming an anisotropic resin magnet, which can ensure the desired residual magnetic flux density.

Another object of the present invention is to provide a mold for molding an anisotropic resin magnet that can ensure a relative positional relationship between a functional member integrally formed with the anisotropic resin magnet and the direction of magnetization of the anisotropic resin magnet.

[0014]

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the objects, a mold for forming an anisotropic resin magnet of the present invention has the following configuration. That is, a molten mixture of magnetic powder and resin is introduced into a cavity made of a non-magnetic material, and a magnetic field is applied to the cavity to orient the magnetic powder to create an anisotropic resin magnet. A mold for molding an anisotropic resin magnet, the spool bushing being provided on the fixed mold side and made of a magnetic material and having a gate having a tapered shape; a central spacer made of a magnetic material, which is disposed opposite to the tapered portion of the bushing and which disposes the cavity at the edge; and a central spacer which is disposed on the movable mold side and is disposed so as to sandwich the cavity. An outer spacer made of a magnetic material and a spacer made of a magnetic material provided on a fixed mold and arranged opposite to the outer spacer are arranged, and the axial magnetic field applied in the moving direction of the movable mold is By applying a parallel magnetic field that acts on the cavity, the magnetic powder is oriented to form an anisotropic resin magnet.

Preferably, the cavity is provided with a mold part for forming a functional member integrally molded with the anisotropic resin magnet.

[0016]

[Operation] In Fig. 3, the cavity C made of non-magnetic material
When a molten mixture of magnetic powder and resin is introduced into the cavity C and an axial magnetic field is applied to the cavity C, a spool made of a magnetic material and having a gate provided on the fixed die side and having a tapered shape part is formed. Between the bush 21, a central spacer 31 made of a magnetic material provided on the movable mold side, an outer spacer 33 made of a magnetic material provided on the movable mold side, and a spacer 35 made of a magnetic material provided on the fixed mold side. A parallel magnetic field is generated that acts on the cavity C, and serves to orient the magnetic powder and form an anisotropic resin magnet.

Furthermore, the functional members are formed with a mutual positional relationship secured by a mold portion for forming the functional members that is integrally molded with the anisotropic resin magnet in the cavity C.

[0018]

[Example] Referring to the drawings, a rotor component 1 consisting of the anisotropic resin magnet and resin functional member described in FIG. An example of molding will be explained. As mentioned above, the rotor component 1 has a cylindrical main body, and the anisotropic pole parts 2 and 3 are polarized in half around the central shaft part 4. The arm support portion 6a is integrally formed, and
An arm portion 6 is formed.

Furthermore, although a protrusion 5 is integrally formed on the lower surface of the anisotropic pole part 3, when the rotor component 1 is integrally formed in this way, the line connecting the arm part 6 and the central shaft part 4 is The following describes a case in which molding is performed so that the direction of magnetization of the anisotropic pole portion 2 and the direction of magnetization of the anisotropic pole portion 2 exactly match. FIG. 1 is a sectional view of a main part of a magnetic field molding die for manufacturing an integrated product of an anisotropic resin magnet according to an embodiment. Although the magnetic field generating means of the magnetic field molding mold is not shown in this figure, the magnetic field molding mold is composed of a fixed mold and a movable mold that are separated from the parting surface P to take out the molded product. . The fixed mold and the movable mold have a well-known configuration, and the movable mold is slidably guided by a guide pin 19 of the fixed mold.

This fixed mold is constructed by fixing a fixed side mounting plate 11 having a resin introduction part and a fixed mold plate 12 using bolts 38. A spool bush 21, which forms a gate G that becomes a flow path for a certain resin, is made of a magnetic material with a high magnetic saturation density and whose tip is constricted as shown in the figure, and a runner R, which is shown by crosshatching below. A fixed piece 36 having a shape formed therein is incorporated.

Further, on the outside of this fixed piece 36,
An upper spacer 3 made of a magnetic material shown in cross-hatching, whose side surface is located on the parting surface P.
5 is included. Next, the movable mold is moved to the movable mold plate 13.
It is composed of a receiving plate 14 and a spacer block 17, and a movable inserting piece 39 is incorporated in the movable mold plate 13. This movable inserting piece 39 is used for ejector pin 3 made of a non-magnetic material in order to push out the product formed in the cavity C.
A guide hole for guiding the gate G in the inserted state and a guide hole for guiding the ejector pin 34 made of a non-magnetic material in order to push out the under part of the gate G in the inserted state are provided.

The other ends of these ejector pins 34 are fixed by the upper ejector plate 16 and the upper ejector plate 15, respectively, which are fixed to the movable side mounting plate 18, and the above-mentioned ejector pins 34 are fixed to the movable side mounting plate 18 by the upper ejector plate 16 and the upper ejector plate 15, respectively. It is designed to perform a push-out operation. Further, an outer spacer 33 made of a magnetic material and shown cross-hatched is incorporated into the outer peripheral surface of the movable inserting piece 39. In addition, movable template 1
A center spacer 31 made of a magnetic material shown cross-hatched and made of a plate member thicker than the thickness of the cavity C in the mold release direction is incorporated in the center part of the cavity C. A cavity block 32 having a cavity C formed therein is further provided at a position sandwiched between the outer spacer 33 and the outer spacer 33 described above. This cavity block 32 is formed with a mold part (not shown) for forming a functional member which is integrally molded with an anisotropic resin magnet.

When a magnetic field molding mold having the above configuration is used and a magnetic field is applied in the axial direction along the mold opening direction, a magnetic field is generated between the spool bush 21 and the center spacer 31, and between the spacer 35 and the outer spacer 33. Since the magnetic circuit is configured, an anisotropic resin magnet can be formed within the cavity C. Next, FIG. 2 shows the parting surface P in FIG.
FIG. In this figure, two cavities C are formed near symmetrical sides of an octagonal central spacer 31. As shown in the figure, the cavity block 32 forming this cavity C is formed of a first cavity block 32a and a second cavity block 32b, which are divided into molds that can be clamped. Block 32 shows the mold opening condition.

On the other hand, the outer spacer 33 has an end 33a forming an angle A with respect to the cavity C, so that the magnetic flux can be concentrated on the cavity C. It is known that even if the angle A is set to a predetermined angle of 52.2×2 degrees or more, magnetic flux cannot be concentrated any further, so it is set to, for example, around 100 degrees. Figure 3 is Figure 1
FIG. 2 is a computer magnetic field analysis diagram of a magnetic field forming mold. In this figure, when an axial magnetic field is generated in the magnetic field molding die in the axial direction, the lines of magnetic force H transmitted through the spool bushing 21 and the center spacer 31 are directed to the spacer 35 and the outer spacer 33 as shown in the figure. It is conveyed as follows.

As is clear from FIG. 3, so-called leakage magnetic flux, which is a line of magnetic force H directed diagonally toward the spacer 35, is observed from the spool bush 21. Furthermore, between the end 31a of the center spacer 31, the end 33a of the outer spacer 33, and the end 35a of the spacer 35, parallel lines of magnetic force H as shown in the figure gather to form parallel magnetic flux. The cavity C for the anisotropic resin magnet is provided between the center spacer 31 and the outer spacer 33 as described above, and a computer magnetic field analysis is performed so that the magnetic fluxes passing through the cavity C are all parallel.

Therefore, we used ferrite particles as ferromagnetic powder and mixed them with synthetic resin to form an anisotropic resin magnet on paper, and then obtained the magnetization curve using a vibrating sample magnetometer. It was found that magnetic properties can be obtained. When the anisotropy rate of the ferrite particles was calculated from this magnetization curve property, it was found to be 83.3%, which indicates that the highest residual magnetic flux density that can be obtained with the ferrite particles can be secured. Furthermore, when the surface residual velocity density of the rotor component 1 was measured, it was found that it exhibited a substantially sinusoidal waveform, indicating that bipolar magnetization was performed in a substantially perfect state.

FIG. 4 is a flowchart for manufacturing the rotor component 1 using the magnetic field forming mold described above. Since this flowchart is a very common flow in magnetic field forming molds, we will only explain its characteristic parts.When preparations for injection of molten resin are completed in steps S1 to S4, an axial magnetic field along the mold opening direction is generated. Preparations are made to orient the ferrite particles generated in step S5.

Thereafter, resin is injected in step S6, the magnetic field is released in step S8, and demagnetization is performed in step S11 to generate a magnetic field of opposite polarity. By applying a magnetic field of opposite polarity in this manner, the anisotropically attached product is completely demagnetized, thereby preventing troubles occurring when the product is attracted by magnetic force in the mold and taken out. After this, the mold is opened in step S13, and the rotor magnet 1 as a product is taken out in step S14.

After this, the rotor magnet 1 shown in FIG. 5 is obtained by applying an axial magnetic field to the product again and magnetizing it, but when applying the axial magnetic field again,
Since the anisotropy rate of the ferrite particles is maximized as described above, it is possible to ensure the highest residual magnetic flux density that can be obtained with the ferrite particles. Furthermore, by forming a female part that integrally forms the functional member on the fixed piece 36 or the input piece 39, the functional member and the anisotropic resin magnet that are integrally formed together with the anisotropic resin magnet formed in the cavity C can be The relative positional relationship in the magnetization direction can be ensured. Furthermore, the functional member and the anisotropic magnet are integrally formed, which shortens the manufacturing process.

[0030] In the above explanation, only a rotor magnet integrally formed with functional parts and used for opening/closing a shutter has been described as an example of a product. Of course, there are many other applications such as driving the iris of a lens system, and the point is that it is particularly effective in manufacturing products in which a functional member and an anisotropic magnet are integrally formed.

[0031]

Effects of the Invention As explained above, according to the present invention, a molding tool for an anisotropic resin magnet is provided that can secure the residual magnetic flux density that should originally be achieved by ferromagnetic powder in molding an anisotropic resin magnet. The mold can be provided. Further, it is possible to provide a mold for molding an anisotropic resin magnet that can ensure the relative positional relationship between the functional member integrally formed with the anisotropic resin magnet and the magnetization direction of the anisotropic resin magnet.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a magnetic field molding die for producing an integrated product of an anisotropic resin magnet according to an example.

FIG. 2 is a plan view of the main parts as seen from the parting surface of FIG. 1 toward the movable mold side.

FIG. 3 is a computer magnetic field analysis diagram of the magnetic field forming mold of FIG. 1;

FIG. 4 is a flow diagram for manufacturing the rotor component 1 using a magnetic field molding die.

FIG. 5 is an external perspective view of an integrated product of an anisotropic resin magnet and a resin functional member.

FIG. 6 is a sectional view of a main part of a magnetic field molding die for manufacturing a conventional anisotropic resin magnet integrated product.

FIG. 7 is a computer magnetic field analysis diagram of the magnetic field forming mold of FIG. 6;

[Explanation of symbols]

1 Rotor magnet 2 Anisotropic polar part 3 Anisotropic polar part 21 Spool bush 31 Center spacer 32 Cavity block 33 Outer spacer 35 Spacer

Claims (3)

[Claims] 1. A molten mixture of magnetic powder and resin is introduced into a cavity made of a non-magnetic material, and a magnetic field is applied to the cavity to orient the magnetic powder to obtain anisotropy. A mold for forming an anisotropic resin magnet for forming a resin magnet, the mold includes a spool bushing made of a magnetic material and having a gate provided on the fixed mold side and having a tapered shape, and a spool bush provided on the movable mold side. and a central spacer made of a magnetic material that is disposed opposite to the tapered portion of the spool bushing and that disposes the cavity at the edge, and a center spacer that is disposed on the movable mold side and is disposed so as to sandwich the cavity. an outer spacer made of a magnetic material, and a spacer made of a magnetic material provided on the fixed mold side and facing the outer spacer. 1. A mold for an anisotropic resin magnet, characterized in that an axial magnetic field acting on the cavity is turned into a parallel magnetic field acting on the cavity, thereby orienting the magnetic powder to form an anisotropic resin magnet. 2. The molded anisotropic resin magnet according to claim 1, wherein the thickness of the magnetic circuit formed between the center spacer and the outer spacer in the thrust direction is greater than the thickness of the cavity. Mold. 3. The molding die for an anisotropic resin magnet according to claim 1, wherein the cavity is provided with a mold part for forming a functional member integrally formed with the anisotropic magnet.