JP2986929B2 - Mold for anisotropic resin magnet - Google Patents

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 having excellent magnet properties.

[0002]

2. Description of the Related Art Conventionally, various methods have been employed to manufacture a rotor component or the like in which a functional member and a cylindrical magnet are integrally provided. In addition, a method of integrally forming a functional member made of resin by insert formation is known.

More specifically, after a cylindrical isotropic sintered magnet is set in an injection mold, a functional member is integrally formed by injecting a synthetic resin such as polyacetal resin having excellent mechanical properties into the cavity. I do. Then, in the next step, the outer peripheral surface of the isotropic sintered magnet is multipolarly magnetized to obtain a finished product. However, when manufacturing by insert formation in this way, it becomes difficult to ensure relative positional accuracy between the functional member made of resin and the polarization position relationship of multipolar magnetization in the next step, so that the phase position of the functional member and the polarized magnetization is Must be arranged in the mold in order to make coincide with each other, but this is difficult to achieve due to restrictions on the mold structure.

Further, when manufactured by insert molding, cracking of the sintered magnet after injection molding becomes a problem. In order to prevent the occurrence of cracks, it is necessary to lower the injection pressure of the molten resin or special measures are required for the injection molding die itself. However, in this case, the dimensions of the functional member formed of the resin are not stable. Therefore, it is not possible to avoid the occurrence of dimensional variation.
Therefore, by manufacturing a functional member and a cylindrical magnet integrally with an anisotropic resin magnet, it is necessary to manufacture a rotor component and the like having better magnetic properties than using an isotropic sintered magnet. Is proposed.

[0005] In this anisotropic resin magnet, a mixture of a ferromagnetic powder and a synthetic resin in a heated and molten state is injected into a magnetic field injection mold into a cavity to which a magnetic field is applied. The easy axis is oriented in a certain direction, and magnetized and magnetized in the next step. FIG. 5 is an external perspective view of an integrated product of an anisotropic resin magnet and a resin functional member. In this figure, a rotor part 1 has a cylindrical main body part having an anisotropic pole part 2.
3 is polarized and magnetized in half with respect to the central shaft portion 4. From the side surface of the anisotropic pole part 2, an arm supporting part 6a is integrally formed, and the arm part 6 is formed. A projection 5 is integrally formed on the lower surface of the anisotropic pole portion 3.

When the rotor component 1 is integrally formed as described above, it is necessary to form the rotor component 1 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 orthogonal. May not be. FIG. 6 is a sectional view of a main part of a conventional magnetic field forming mold for manufacturing an integrated product of the anisotropic resin magnet of FIG. In this drawing, 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 which are separated from the parting surface P to take out a molded product. .

This fixed mold is constituted by fixing a fixed-side mounting plate 11 having a resin introduction portion and a fixed mold plate 12 using bolts 38, while the fixed mold plate 12 is in a molten state. A gate G serving as a flow path for a certain resin is formed, and a spool bush 21 made of a magnetic material having a high magnetic saturation density and cross-hatched, and a fixed piece 36 having a runner R are incorporated therein.

Next, the movable mold is composed of a movable mold plate 13 and a receiving plate 14.
The movable mold plate 13 has a movable receiving piece 39 incorporated therein. The movable insertion piece 39 has a guide hole for guiding an ejector pin 34 for pushing out a product formed in the cavity C in an inserted state, and a guide hole for guiding the ejector pin 34 for pushing out an under part of the gate G in an inserted state. Are drilled.

An outer spacer 3 made of a magnetic material shown by cross hatching is provided on the outer peripheral surface of the movable input piece 39.
3 are incorporated. Further, a central spacer 31 made of a magnetic material shown by cross hatching is incorporated in a central portion of the movable mold plate 13.
A cavity block 32 having a cavity C is provided at a position between the outer spacer 33 and the outer spacer 33.

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

[0011]

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. 6 and 7, the influence of the magnetic field line H transmitted obliquely. , Cavity C
As a result, the anisotropic resin magnet causes a decrease in the anisotropic ratio of the ferromagnetic powder, which is originally achieved by the ferromagnetic powder. There was a problem that it was not possible to secure the required residual magnetic flux density. Further, when the surface residual magnetic flux density was measured after manufacturing with this magnetic field forming die, it was found that a substantially distorted portion was found at the peaks and valleys having a substantially sinusoidal waveform, and it was found that there was variation in the two-pole magnetization.

Furthermore, there is a problem that it is difficult to secure a 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 of the anisotropic resin magnet of the present invention has been made in view of the above-mentioned problems, and its object has been originally achieved by the ferromagnetic powder in the molding of the anisotropic resin magnet. An object of the present invention is to provide a molding die of an anisotropic resin magnet capable of securing a residual magnetic flux density to be performed.

It is another object of the present invention to provide a molding die for an anisotropic resin magnet which can secure a relative positional relationship between a functional member integrally formed with the anisotropic resin magnet and a magnetizing direction of the anisotropic resin magnet.

[0014]

Means for Solving the Problems In order to solve the above-mentioned problems and achieve the object, a molding die for anisotropic resin magnet of the present invention has the following configuration. That is, a mixed melt of a magnetic powder and a resin body 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 so that an anisotropic resin magnet is formed. A mold for forming an anisotropic resin magnet, comprising: a spool bushing provided on a stationary mold side and having a gate having a tapered portion; and a spool bushing provided on a movable mold side and provided with the spool. A central spacer made of a magnetic material that is disposed to face the tapered portion of the bush and has the cavities disposed at the edges; and a central spacer that is provided on the movable mold side and sandwiches the cavities. An outer spacer made of a magnetic material, and a spacer made of a magnetic material provided on the stationary mold and opposed to the outer spacer are provided, and an axial magnetic field applied in a moving direction of the movable mold is provided. Said By the parallel magnetic field acting on Yabitei, said by the orientation of the magnetic powder is a configuration for molding the resin magnet anisotropic.

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

[0016]

FIG. 3 shows a cavity C made of a non-magnetic material.
When a molten mixture of a magnetic powder and a resin body is introduced into the inside and an axial magnetic field is applied to the cavity C, a spool made of a magnetic body having a gate provided on the fixed mold side and having a tapered portion is provided. 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 As a result, a parallel magnetic field acting on the cavity C is generated, which acts to orient the magnetic powder and form an anisotropic resin magnet.

Further, the functional members are formed in the cavity C by a mold part for forming the functional members integrally formed with the anisotropic resin magnet while securing the mutual positional relationship.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, a rotor component 1 comprising an anisotropic resin magnet and a resin functional member described in FIG. An example of molding is described. As described above, the rotor component 1 has a cylindrical main body portion in which the anisotropic pole portions 2 and 3 are polarized and attached in half around the central axis portion 4. Is formed integrally with the arm supporting portion 6a,
An arm 6 is formed.

A projection 5 is integrally formed on the lower surface of the anisotropic pole portion 3. In the case where the rotor component 1 is integrally formed as described above, a line connecting the arm 6 and the central shaft 4 is formed. A description will be given by taking up a case in which molding is performed so that the magnetization direction of the anisotropic pole portion 2 exactly matches. 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. 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 which are separated from the parting surface P to take out a molded product. . The fixed mold and the movable mold have a known configuration, and the movable mold is slidably guided by a guide pin 19 of the fixed mold.

This fixed mold is formed by fixing a fixed mounting plate 11 having a resin introduction portion and a fixed mold plate 12 with bolts 38, while the fixed mold plate 12 is in a molten state. A gate bush 21 which is formed of a magnetic material having a high magnetic saturation density and which is formed by cross-hatching and has a tip narrowed as shown in FIG. Is fixed.

Further, further outside the fixed piece 36,
Upper spacer 3 made of a magnetic material shown by cross-hatching so that the side surface is positioned on the partition surface P.
5 are incorporated. Next, the movable mold is a movable mold plate 13.
, A receiving plate 14 and a spacer block 17.
The movable input piece 39 is used to push out a product formed in the cavity C.
A guide hole for guiding the underside of the gate 4 in the inserted state and a guide hole for guiding the ejector pin 34 made of a non-magnetic material in the inserted state for pushing out the under part of the gate G are formed.

The other ends of these ejector pins 34 are fixed by an upper ejector plate 16 and an upper ejector plate 15 which are fixed to the movable side mounting plate 18, respectively. Push-out operation. An outer spacer 33 made of a magnetic material shown by cross hatching is incorporated in the outer peripheral surface of the movable insertion piece 39. In addition, the movable mold plate 1
A central spacer 31 made of a magnetic material shown in a cross-hatched manner and a plate member thicker than the thickness of the cavity C in the releasing direction is incorporated as shown in FIG. A cavity block 32 in which a cavity C is formed is further provided at a position between the outer spacer 33 and the outer spacer 33. The cavity block 32 is provided with a mold (not shown) for forming a functional member integrally formed with the anisotropic resin magnet.

When a magnetic field is applied in the axial direction along the mold opening direction by using the magnetic field forming mold having the above-described configuration, the space between the spool bush 21 and the center spacer 31 and between the spacer 35 and the outer spacer 33 is increased. Since the magnetic circuit is configured, the anisotropic resin magnet can be formed in the cavity C. Next, FIG. 2 shows the partition surface P of FIG.
FIG. 5 is a plan view of a main part when the movable mold side is viewed from FIG. In this figure, two cavities C are formed near the symmetrical sides of the octagonal center spacer 31. The cavity block 32 forming the cavity C is composed of a first cavity block 32a which is divided so as to be mold-clampable as shown in the figure, and a second cavity block 32a.
The cavity block 32b is formed from the cavity block 32b, and the cavity block 32 on the lower side in the figure shows the opened state.

On the other hand, the outer spacer 33 has a shape in which the end 33a forms an angle A with respect to the cavity C, so that the magnetic flux can be concentrated on the cavity C.
Even if this angle A is set to a predetermined angle of 52.2 × 2 degrees or more, it is known that no more magnetic flux can be concentrated, so it is set to, for example, about 100 degrees. FIG. 3 is FIG.
FIG. 4 is a computer magnetic field analysis diagram of the magnetic field forming die of FIG. In this drawing, when an axial magnetic field is generated in the magnetic field forming mold in the axial direction, the magnetic field lines H transmitted via the spool bush 21 and the center spacer 31 are applied to the spacer 35 and the outer spacer 33 as shown in FIG. Transmitted.

As is apparent from FIG. 3, a so-called leakage magnetic flux, which is a line of magnetic force H directed obliquely directly to the spacer 35, is recognized from the spool bush 21. Also, the end 31a of the center spacer 31 and the end 33a of the outer spacer 33
Between the end portions 35a of the spacer 35, the parallel lines of magnetic force H as shown gather to form a 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, but the computer magnetic field analysis is performed so that all magnetic fluxes passing through the cavity C are parallel.

Therefore, ferrite particles were used as ferromagnetic powder and mixed with a synthetic resin. After forming an anisotropic resin magnet on paper, a magnetization curve was obtained with a vibrating sample magnetometer. It has been found that magnetic properties can be obtained. When the anisotropy ratio of the ferrite particles was calculated from this magnetization curve property, it was 83.3%, which proved that the highest residual magnetic flux density obtainable by the ferrite particles could be secured. Further, when the surface residual velocity density of the rotor component 1 was measured, it was found that the rotor component 1 had a substantially sinusoidal waveform and the two-pole 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 flow chart is an extremely general flow in a magnetic field forming mold, only the characteristic portions will be described. When the molten resin is ready to be injected at steps S1 to S4, an axial magnetic field along the mold opening direction is generated. In step S5, preparations are made to orient the ferrite particles.

Thereafter, resin injection is performed in step S6, the magnetic field is released in step S8, demagnetization is performed in step S11, and a magnetic field of the opposite polarity is generated. By applying a magnetic field of the opposite polarity in this way, the anisotropically landed product is completely demagnetized, thereby preventing troubles when the product is attracted and removed by magnetic force in the mold. Thereafter, the mold is opened in step S13, and the rotor magnet 1 of the product is taken out in step S14.

After that, the rotor magnet 1 shown in FIG. 5 is obtained by applying an axial magnetic field again to the product and magnetizing it. When the axial magnetic field is again applied, the rotor magnet 1 shown in FIG.
Since the anisotropy ratio of the ferrite particles is maximized as described above, the highest residual magnetic flux density obtainable by the ferrite particles can be secured. Further, by forming the female part integrally forming the functional member on the fixed piece 36 or the input piece 39, the functional member and the anisotropic resin magnet integrally formed with the anisotropic resin magnet formed in the cavity C are formed. The relative positional relationship in the magnetization direction can be secured. Furthermore, the functional member and the anisotropic magnet are integrally formed, thereby shortening the process.

In the above description, as an example of a product, only an example of a rotor magnet integrally formed with a functional component and used for opening and closing a shutter has been described. However, the present invention is not limited to this. Of course, there are many other things such as for driving iris of a lens system, and the point is that it is particularly effective for manufacturing a product in which a functional member and an anisotropic magnet are integrally formed.

[0031]

As described above, according to the present invention, in forming an anisotropic resin magnet, a molding metal for an anisotropic resin magnet capable of securing a residual magnetic flux density which should be originally achieved by a ferromagnetic powder. Types can be provided. Further, it is possible to provide a molding die for an anisotropic resin magnet which can ensure a relative positional relationship between a functional member integrally formed with the anisotropic resin magnet and the anisotropic resin magnet in a magnetization direction.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a magnetic field forming mold for manufacturing an integrated product of an anisotropic resin magnet according to an embodiment.

FIG. 2 is a plan view of a main part when the movable mold side is viewed from the parting surface of FIG. 1;

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

FIG. 4 is a flowchart for manufacturing a rotor component 1 using a magnetic field forming 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 cross-sectional view of a main part of a magnetic field forming mold for manufacturing an integrated product of a conventional anisotropic resin magnet.

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

[Description of Signs] 1 Rotor magnet 2 Anisotropic pole part 3 Anisotropic pole part 21 Spool bush 31 Center spacer 32 Cavity block 33 Outer spacer 35 Spacer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 45/26-45/44 B29C 33/00-33/76

Claims (3)

(57) [Claims] A mixed melt of a magnetic powder and a resin body is introduced into a cavity made of a non-magnetic material, and a magnetic field is applied to the cavity to cause the magnetic powder to be oriented to anisotropically. A molding die of an anisotropic resin magnet forming the resin magnet of the above, wherein a spool bush made of a magnetic material having a gate provided on the fixed mold side and having a tapered shape portion,
A center spacer made of a magnetic material provided on the movable mold side and arranged to face the tapered portion of the spool bush and disposing the cavity at an edge; and An outer spacer made of a magnetic material provided so as to sandwich the cavities, and a spacer made of a magnetic material provided on the fixed mold side and opposed to the outer spacer. An anisotropic resin magnet characterized by forming an anisotropic resin magnet by orienting the magnetic powder by changing an axial magnetic field applied in the moving direction of the magnetic field to a parallel magnetic field acting on the cavity. Molding mold. 2. A were to constitute a magnetic circuit that forms a Oite parallel flux between the outer spacer and the central spacer
2. The molding die for an anisotropic resin magnet according to claim 1 , wherein the thickness of the center spacer and the outer spacer in the mold release direction is greater than the thickness of the cavity. 3. The molding die for anisotropic resin magnet according to claim 1 , wherein the cavity is provided with a mold portion for forming a functional member integrally formed with the anisotropic magnet.