JP2000164444A - Mold for magnetic-field generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for magnetic-field generator which can produce a highly oriented molded product without increasing the number of processes and cost. SOLUTION: A mold 21 is used for an magnetic-field generator and has an internal cavity 31 to which a molding resin material 2 containing magnetic powder is supplied. When the material 2 is supplied, a magnetic filed is applied upon the cavity 21 from a prescribed direction. The sections P1 of the mold 21 from which the lines of magnetic force forming the magnetic field are apt to leak out are formed by using a first material having a relatively small residual magnetic flux density Br. The other section of the mold 21 is formed by using a second material having a larger residual magnetic flux density Br than the first material has.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for a magnetic field molding machine.

[0002]

2. Description of the Related Art FIG. 7 shows an example of a conventional mold 44 for a magnetic field molding machine for performing magnetic field molding. The mold 44 for a magnetic field molding machine is made of a magnetic material and includes a movable mold 42 and a fixed mold 43. When the movable mold 42 and the fixed mold 43 are closed, a cavity 45 is formed at the interface between them. In the cavity 45, for example, a cylindrical base material 4 is provided.
6 is inserted, and a resin molding material 48 containing magnetic powder (not shown) is supplied in this state. At the time of material supply, a magnetic field is applied to the cavity 45 from a vertical direction in FIG. Then, as shown in FIG. 8, a magnetic field molded product in which the magnetic powder 47 in the resin molding material 48 is oriented can be obtained.

[0003]

By the way, when a magnetic field is applied to the mold 44 from a predetermined direction, the lines of magnetic force are usually almost parallel as shown by the broken line in FIG. However, among the surfaces defining the cavity 45 in the mold 44, for example, at a position P1 or the like to which a surface perpendicular to the magnetic field direction A1 belongs, the lines of magnetic force are
(5) It is easy to leak outside. In other words, originally,
The lines of magnetic force to pass through the resin molding material 48 bypass the region outside the cavity 45 made of a magnetic material. Therefore, as shown in FIG. 8, the magnetic field near the location P1 is weakened, and the orientation state of the magnetic powder 47 existing there is worse than in other parts. Therefore, even if the magnetic field molded article obtained in this way is magnetized later, it becomes difficult to obtain a suitable anisotropic magnet having a strong magnetic force.

[0004] As a method of obtaining a suitable anisotropic magnet, for example, a method is employed in which a portion having a poor orientation state in the resin molding material 48 is removed by a predetermined thickness by cutting, and then magnetized. It is possible. However, this method involves cutting, which increases the number of steps. Further, since a loss occurs in the material, the cost may be increased.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a magnetic field molding machine capable of obtaining a magnetic field molded article having a good orientation state without increasing the number of steps or increasing the cost. To provide a metal mold.

[0006]

In order to solve the above problems, according to the first aspect of the present invention, a cavity for supplying a resin molding material containing magnetic powder is formed therein, A mold for a magnetic field molding machine configured to apply a magnetic field to the same cavity from a predetermined direction at the time of supplying the resin molding material, wherein a magnetic field line forming the magnetic field easily leaks out of the cavity. In addition to forming the first material having a small residual magnetic flux density, the remaining portions are formed using a second material having a relatively large residual magnetic flux density than the first material. The feature of the invention is a mold for a magnetic field forming machine.

According to a second aspect of the present invention, in the first aspect, of the surfaces defining the cavity, a portion to which a surface perpendicular to the direction of the magnetic field belongs belongs to the first region.
Was formed using the above material.

According to a third aspect of the present invention, in the first or second aspect, the residual magnetic flux density of the first material is less than the second magnetic flux density.
Of the material was 1/1000 or less of the residual magnetic flux density of the material. According to a fourth aspect of the present invention, in any one of the first to third aspects, the first material is a non-magnetic material and the second material is a magnetic material.

[0009] The invention according to claim 5 is the invention according to claims 1 to 4.
In any one of the above, when the width of the cavity along the direction of the magnetic field is T, the thickness of a portion formed of the first material in a direction orthogonal to the direction of the magnetic field is: , At least T / 2.

Hereinafter, the "action" of the present invention will be described. According to the first aspect of the present invention, since the first material has a relatively small residual magnetic flux density, it is difficult for the magnetic field lines to leak out of the cavity from the location. therefore,
The lines of magnetic force pass through the location on the resin molding material side corresponding to the location, and the magnetic field therefrom is also prevented from weakening. Therefore, if molding is performed using a magnetic field molding machine equipped with such a mold, the orientation state of the magnetic powder present at the relevant location can be improved. Therefore, a suitable magnetic-field molded product can be obtained. In addition, since it is not necessary to perform a grinding process or the like after molding, an increase in the number of steps and an increase in cost can be avoided.

According to the second aspect of the present invention, the leakage of the lines of magnetic force in a portion to which a plane perpendicular to the direction of the magnetic field belongs is prevented. As a result, the orientation state of the magnetic powder present at the location on the resin molding material side corresponding to the location is improved.

According to the third aspect of the present invention, the residual magnetic flux density of the first material is 1/1 / the of the residual magnetic flux density of the second material.
It is set so as to be 1000 or less, and the difference in residual magnetic flux density becomes sufficiently large. Therefore, by selecting such two kinds of materials, the action of preventing the leakage of the lines of magnetic force becomes more reliable.

According to the invention described in claim 4, the first material is a non-magnetic material and the second material is a magnetic material.
The effect of preventing the leakage of the lines of magnetic force is further ensured.

According to the fifth aspect of the present invention, the thickness required to obtain the function of preventing the leakage of the magnetic field lines is secured at the portion formed of the first material.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mold for a magnetic field injection molding machine according to an embodiment of the present invention and a method for manufacturing a magnetic field molded article (anisotropic magnet) using the same will be described with reference to FIGS. This will be described in detail based on FIG.

FIGS. 1 and 2 show a magnetic field molded product 1 of the present embodiment. The magnetic field molded article 1 is a molded article (that is, an insert molded article) in which a base material 4 made of another material is inserted into a flange portion 3 made of a resin molding material 2. The molded article 1 is a rotating body having a rotationally symmetric shape.

In the present embodiment, a general thermoplastic resin such as nylon is used as the resin molding material 2. The resin molding material 2 contains the magnetic powder 5 together with a small amount of additives. In this embodiment, Sr ferrite is used as the magnetic powder 5. As conceptually shown in FIG. 5B, the Sr ferrite crystal is a hexagonal plate-shaped crystal having an average particle size of about 1.2 μm.
And the average thickness is 0.2 μm. In the drawing, the easy axis 6 of the Sr ferrite crystal is indicated by an arrow. The easy axis 6 is perpendicular to the plane direction of the crystal.

As the substrate 4, a sleeve made of a ceramic sintered body having a cylindrical shape is selected. Examples of the ceramic sintered body used here include a dense alumina sintered body. The alumina sintered body is a non-magnetic material. The outer peripheral surface 4 a of the base material 4 is in close contact with the inner peripheral surface 3 a of the flange portion 3 made of the resin molding material 2.

The molded article 1 is subsequently magnetized to become an anisotropic magnet. In the present embodiment, the surface layer of the outer peripheral surface 3b of the flange portion 3 is magnetized, and a permanent magnet (not shown) is formed at the location. Therefore,
An anisotropic magnet formed by magnetizing the molded article 1 can be used as, for example, a thrust bearing member of a motor in a dental polishing apparatus.

FIG. 3 shows a main part of a magnetic field injection molding machine 11 for manufacturing the magnetic field molded article 1. A movable plate 12 and a fixed plate 13 are installed on a base constituting the magnetic field injection molding machine 11 so as to face each other. In FIG. 3, a link mechanism 14 as driving means for closing and opening the mold is connected to the outer end face side of the movable platen 12. Therefore, the movable platen 12 can be moved by the link mechanism 14 by a predetermined length in the vertical direction in FIG.

On the other hand, on the outer end face side of the fixed platen 13, a nozzle portion 16 at the tip of the screw cylinder 15 is arranged. At the base end side of the screw cylinder 15 as a material supply means, a hopper (not shown) for charging a raw material is provided. The screw cylinder 15 can move forward and backward by a predetermined length along its own longitudinal direction. Therefore, when the screw cylinder 15 is at the forward position, the nozzle portion 16 is inserted into a through-hole (not shown) provided in the fixed platen 13.

A magnetic field generating means 17 is housed inside the movable platen 12 and the fixed platen 13. The magnetic field generating means 17 in the present embodiment is an electromagnet 18 having a coil wound around a core, and generates a strong magnetic field when energized. A plurality of tie bars 19 made of a magnetic material such as iron are interposed between the movable platen 12 and the fixed platen 13. Therefore, these tie bars 19 serve as a return yoke when the electromagnet 18 forms a closed magnetic circuit.

This magnetic field injection molding machine 11 has a mold 21. As shown in FIGS. 3 and 4, the mold 21 includes a movable mold 22 and a fixed mold 23. The movable die 22 is attached to a central portion on the inner end surface side of the movable platen 12, and the fixed die 23 is attached to a central portion on the inner end surface side of the fixed platen 13. That is, the movable mold 22 and the fixed mold 23
Are arranged in a state of facing each other.

A circular recess 24 is formed at the center of the inner end surface of the fixed die 23, and a column 25 is formed at the center of the recess 24. The fixed mold 23 has a plurality of gates 26. One end of each gate 26 is recessed 24
And the other end reaches the through hole where the nozzle portion 16 is inserted.

The movable mold 22 is constructed by assembling two mold pieces 27 and 28 integrally. The sub-mold piece 28 formed in a cylindrical shape is arranged on the outer peripheral portion so as to surround the main mold piece 27. The inner end surface side of the movable mold 22 is formed in a concave shape, and a circular concave portion 30 is formed on the bottom surface thereof.
Is provided.

When the mold is closed, a cavity 31 is formed at the interface between the movable mold 22 and the fixed mold 23. More specifically, the fixed type 23
The cavity 31 is defined by the inner end face of the main mold piece 27, the inner end face of the main mold piece 27, and the inner peripheral face 28a of the sub mold piece 28.

As a material for forming the fixed mold 23, a ferrous metal (a steel material as a magnetic material) which is a magnetic material, more specifically, an SK material (a JIS G material) which is a carbon tool steel material in the present embodiment.
4401) is used. The value of the residual magnetic flux density Br of the metal material is 0.1 to 1.0 (T: Tesla). The same metal material as described above is also used for the material for forming the main mold piece 27 of the movable mold 22. In addition, SKH material (JIS G 4403) which is a high speed tool steel material, SKS material, SKD material and SKT material which are alloy tool steel materials (JIS
G 4404) may be used.

On the other hand, the forming material (ie, the first material) of the sub-mold piece 28 of the movable mold 22 includes the fixed mold 23 and the main mold piece 2.
A material different from the forming material of No. 7 (that is, the second material) is used. That is, the forming material of the sub-mold piece 28 is
In addition, it is necessary that the residual magnetic flux density Br is relatively small as compared with the material for forming the main mold piece 27.

The sub-mold piece 28 defining the cavity 31
The inner peripheral surface 28a has a direction A of magnetic field as shown in FIG.
The plane is perpendicular to 1 (that is, the direction A1 of the line of magnetic force). The portion P1 to which the surface 28a belongs is a portion P1 where magnetic lines of force are originally apt to leak out of the cavity 31.
You can say that. From the above, in the present embodiment, the sub-mold piece 28 made of the first material having a relatively low residual magnetic flux density Br is disposed at the location P1.

The width of the cavity 31 along the direction A1 of the magnetic field (more specifically, in this embodiment, the width of the cavity 31 at the outer peripheral portion of the flange 3 (FIGS. 4 and 5)
(See (a))) is T. At this time, the thickness W of the portion P1 formed of the first material in the direction orthogonal to the direction A1 of the magnetic field is set to at least T / 2 or more, preferably T or more, and more preferably 2T or more. Is better. If the thickness W is too small, the function of preventing the leakage of the lines of magnetic force may not be sufficiently secured at the point P1. If the thickness W does not have a certain level, the mold 21 cannot have sufficient mechanical strength, and cannot withstand the pressure applied from the cavity 31 during the material injection.

In this embodiment in which the width of the cavity 31 is set to T = 4.0 mm, the thickness W is set to a sufficiently large value, specifically, to about W = 8 mm. Further, the residual magnetic flux density Br of the first material is 1/100 or less, more preferably 1/250 or less, especially 1/250 of the residual magnetic flux density Br of the second material.
It is preferably 1000 or less. This is because by selecting two kinds of materials having a sufficiently large difference in residual magnetic flux density Br, the function of preventing leakage of the lines of magnetic force becomes more reliable. The first material is preferably a completely non-magnetic material, rather than a weak magnetic material or semi-magnetic material. This is because the lines of magnetic force have the property of hardly passing through the non-magnetic material. On the other hand, the second material is preferably a ferromagnetic material.

From the above, in the present embodiment, the
Austenitic stainless steel (that is, SUS300 series) is selected as the material for (1). Austenitic stainless steel is a non-magnetic material. The surface of the stainless steel is preferably subjected to a surface treatment to increase the hardness.

Next, an example of a method for manufacturing the magnetic field molded article 1 using the magnetic field injection molding machine 11 will be described. In an initial state, the mold 21 is opened, and the resin molding material 2 in a heated and molten state is supplied in advance into the hopper. The screw cylinder 15 is at the retracted position, and the nozzle portion 16 is not inserted into a through hole (not shown) provided in the fixed platen 13.

Here, the base material 4 is attached to the cylindrical portion 25 of the fixed mold 23.
Are set so as to be fitted together, and then the link mechanism 14 is set.
By driving the movable mold 22 by driving the
Close the mold.

Next, by energizing the electromagnet 18 to generate a magnetic field, a closed magnetic circuit as shown in FIG. 3 is formed. The direction A1 of the magnetic field generated at this time is a direction from the upper side to the lower side in FIG. The lines of magnetic force forming the magnetic field are parallel as shown by the broken lines in FIG. 4, enter the cavity 31 from the fixed mold 23 side, pass through the cavity 31 and escape to the movable mold 22 side.

Subsequently, the screw cylinder 15 is advanced to an inserted state, and the molten resin molding material 2 is transferred to the gate 26.
And is injected into the cavity 31 through. As a result, the cavity 31 is completely filled with the resin molding material 2. At this time, the magnetic lines of force passing through the cavity 31 act on the magnetic powder 5 in the resin molding material 2 and cause the easy axis 6 to be directed in the direction A1 of the magnetic field in a very short time. That is, the magnetic powder 5 is oriented in a specific direction by the action of the lines of magnetic force.

When several seconds to several tens of seconds have elapsed after the injection, the resin molding material 2 cools and hardens, and as a result, the magnetic field molded product 1 in which the inserted base material 4 and the resin molding material 2 are integrated is obtained. Can be Thereafter, the mold 21 is opened, and the magnetic field molded product 1 is taken out of the cavity 31. Furthermore, if a permanent magnet is formed on the outer layer 3b of the flange portion 3 by performing a magnetizing operation using a dedicated thrust magnetizing yoke (not shown), a desired anisotropic magnet is completed.

[0038]

EXAMPLES [Test Method] Here, a sample of an example and a sample of a comparative example were prepared, and a test for comparing both samples was performed.

In the embodiment, the mold 21 shown in FIG. 4 is used, and the magnetic field molded article 1 is first manufactured according to the above-described method, and then, under a predetermined condition (1000
V) The magnet was fully magnetized. As shown in FIG. 6A, the lower half of the permanent magnet formed on the surface layer of the outer peripheral surface 3b has N poles and the upper half has S poles. The thickness of the outer peripheral portion of the flange portion 3 is 4.0 mm, which is equal to the width T of the cavity 31. The reference (zero reference) of the position in the thickness direction of the anisotropic magnet is set at the height of the upper end face of the flange portion 3.

On the other hand, in the comparative example, a magnetic field molded product was manufactured using the mold shown in FIG. Then, this was magnetized under the same conditions as above to obtain an anisotropic magnet. The strength of the surface magnetic flux density (mT) on the outer peripheral surface 3b of the flange portion 3 was measured for each of the obtained two samples by a conventionally known method. The result of the example is shown in the graph of FIG. 6C, and the result of the comparative example is shown in the graph of FIG. 6B.

For the two types of samples, the flange portion 3 was cut in parallel along the axial direction, and the cross section of the surface layer of the outer peripheral surface 3b was observed with a SEM using a microscope.
Thereby, the orientation state of the magnetic powder 5 was investigated. [Results] As can be seen by comparing FIGS. 6B and 6C, the difference in the surface magnetic flux density between the sample of the example and the sample of the comparative example was larger than that of the sample of the comparative example.
Therefore, it was confirmed that the sample of the example had a better magnetized state on the surface layer of the outer peripheral surface 3b and was a suitable anisotropic magnet having a strong magnetic force.

FIG. 5 shows the result of microscopic observation.
As schematically shown in (a) and (b), in the sample of the example, the orientation state of the magnetic powder 5 in the surface layer of the outer peripheral surface 3b was extremely high. In contrast, FIG.
As schematically shown in (a) and (b), in the sample of the comparative example, the orientation state of the magnetic powder 5 at the same location was not so high. That is, in the example, it is concluded that the magnetic field did not weaken in the vicinity of the point P1 where the magnetic lines of force easily leak out of the cavity 31, and the orientation state of the magnetic powder 5 existing there did not deteriorate.

Therefore, according to the present embodiment, the following effects can be obtained. (1) Magnetic field injection molding machine 1 provided with mold 21 of the present embodiment
If the molding is performed by using No. 1, the orientation state of the magnetic powder 5 present on the surface layer of the outer peripheral surface 3b of the flange portion 3 can be improved. Therefore, it is possible to obtain a suitable magnetic-field molded product 1 and a suitable anisotropic magnet. In addition, since it is not necessary to perform a grinding process or the like after molding, an increase in the number of steps and an increase in cost can be avoided.

(2) In the mold 21 of the present embodiment, the first material used for the sub-mold piece 28 of the movable mold 22 is a non-magnetic material,
The second material used for the main mold piece 27 and the fixed mold 23 of the movable mold 22 is a magnetic material. Therefore, the difference in the residual magnetic flux density Br is certainly 1000 times or more, and is sufficiently large. Therefore, by selecting such two kinds of materials, the effect of preventing the leakage of the lines of magnetic force can be further ensured. As a result, it is possible to obtain the magnetic field molded product 1 having an extremely good orientation state in the surface layer of the outer peripheral surface 3b of the flange portion 3.

The embodiment of the present invention may be modified as follows. As the first material, a stainless steel that is not austenitic and is not a magnetic material may be used, or an iron-based metal other than stainless steel that is not a magnetic material may be selected. It is also acceptable to use a ceramic sintered body such as silicon carbide or silicon nitride as the non-magnetic material other than the metal. When such a ceramic sintered body is selected, there is an advantage that the sub-mold piece 28 constituting the mold 21 can be formed with high precision.

The use of a material that is not completely non-magnetic as the first material to form the mold 21 is also permitted.
Specifically, a weak magnetic material may be used as the first material and a ferromagnetic material may be used as the second material.

The substrate 4 inserted into the cavity 31 is not limited to the cylindrical member as in the embodiment, but may be any other member (for example, a plate member, a rod member, It is of course possible to change to a spherical object. At that time, the manufactured magnetic field molded body 1 does not necessarily have to be a rotating body.

Similarly, the material of the substrate 4 can be changed to a material other than the alumina sintered body. For example,
Select ceramic sintered body other than alumina sintered body,
Further, it is also acceptable to select a material other than the ceramic sintered body (that is, a metal material, a resin material, or the like).

Magnetic powder 5 contained in resin molding material 2
May be other than the Sr ferrite exemplified in the embodiment, for example, Ba ferrite, Co ferrite, Pb ferrite, or the like. In addition, a polyamide resin other than nylon can be selected as the resin molding material 2, or a resin other than polyamide resin and having thermoplasticity can be selected.

According to the present invention, the base material 4 is provided in the cavity 31.
The same can be applied to the case where the magnetic field molding is performed using only the resin molding material 2 without inserting any. That is, the present invention is not necessarily applied only to the manufacture of insert molded products.

A first material having a relatively small residual magnetic flux density, typified by a nonmagnetic material, is arranged at a location other than the location indicated by P1 in FIG. 4 (eg, P2, P3 in FIG. 4). You may. This is because these portions P2 and P3 also have vertical surfaces belonging to the direction A1 of the magnetic field as a reference similarly to P1, so that the lines of magnetic force may leak out of the cavity 31.

The movable mold 22 is divided into two main and sub mold pieces 27, 28, one of which is formed of the first material, and the fixed mold 23 is mainly used. ,
It may be divided into two sub-pieces 27 and 28 and configured similarly.

The mold 21 of the present invention may of course be used for a magnetic field molding machine that performs molding by a method other than injection molding. Next, in addition to the technical ideas described in the claims, technical ideas grasped by the above-described embodiments are listed below together with their effects.

(1) In any one of claims 1 to 5, the mold comprises a pair of a movable mold and a fixed mold,
One of the movable mold and the fixed mold is constituted by a main mold piece made of the second material, and a sub mold piece made of the first material and surrounding an outer peripheral portion of the main mold piece. That you are.

(2) The method according to any one of claims 1 to 5, wherein the first material is stainless steel. Therefore, according to the invention of Technical Concept 2, since the material is excellent in workability, a mold can be manufactured relatively inexpensively and easily even in a complicated shape.

(3) The method according to any one of claims 1 to 5, wherein the first material is a ceramic sintered body. Therefore, according to the invention of the technical idea 3, since it is a ceramic sintered body, it can be formed with relatively high precision.

(4) The mold according to any one of claims 1 to 5 and technical ideas 1 to 3, driving means for closing and opening the mold, and a mold for driving the mold. A magnetic field molding machine comprising: a magnetic field generating means for applying a magnetic field from a predetermined direction; and a material supply means for supplying a molten resin molding material into a cavity of the mold formed when the mold is closed.
Therefore, if the magnetic field forming machine according to the invention described in the technical idea 4 is used, it is possible to obtain a magnetic field formed product having a good orientation state without increasing the number of steps or increasing the cost.

(5) A cavity for supplying a resin molding material containing magnetic powder is formed therein, and a magnetic field is applied to the cavity from a predetermined direction when the resin molding material is supplied. In carrying out a magnetic field molding method using a mold for a magnetic field molding machine, two or more mold materials having different residual magnetic flux densities are appropriately arranged on a surface of the mold that partitions the cavity. A method for controlling the orientation state of the magnetic powder, wherein the orientation state of the magnetic powder is arbitrarily controlled.

[0059]

As described in detail above, according to the first to fifth aspects of the present invention, the object is to provide a magnetic-field molded article having a good orientation without increasing the number of steps or increasing the cost. A mold for a magnetic field molding machine that can be obtained can be provided.

According to the third aspect of the present invention, since the function of preventing the leakage of the lines of magnetic force is more reliable, it is possible to obtain a magnetic field molded product having a better orientation state. According to the fourth aspect of the present invention, since the function of preventing the leakage of the lines of magnetic force is further ensured, it is possible to obtain a magnetic field molded product having an extremely good orientation state.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a magnetic field molded product (anisotropic magnet) of one embodiment embodying the present invention.

FIG. 2 is a sectional view showing a magnetic field molded product (anisotropic magnet).

FIG. 3 is a schematic front view showing a main part of the magnetic field injection molding machine in the embodiment.

FIG. 4 is a sectional view of a mold for a magnetic field injection molding machine according to the embodiment.

5A is a view conceptually showing the orientation state of magnetic powder contained in a resin molding material in a portion where leakage of magnetic force lines is likely to occur, and FIG. FIG.

6A is a schematic cross-sectional view of an anisotropic magnet for explaining a comparative test method, FIG. 6B is a graph showing data of a comparative example, and FIG. 6C is a graph showing data of an example.

FIG. 7 is a cross-sectional view of a conventional mold for a magnetic field injection molding machine.

FIG. 8A is a diagram conceptually showing the orientation state of magnetic powder contained in a resin molding material in a portion where leakage of magnetic force lines is likely to occur, and FIG. FIG.

[Explanation of symbols]

2: resin molding material, 5: magnetic powder, 11: magnetic field injection molding machine as a magnetic field molding machine, 21: magnetic field injection molding machine mold as a magnetic field molding machine mold, 28: sub-mold piece, 28a: magnetic field Inner peripheral surface of the sub-mold piece as a plane perpendicular to the direction of
1. Cavity, P1: Location where magnetic lines of force easily leak out of the cavity, T: Width of cavity, A1: Direction of magnetic field.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Niwa, Inventor Takashi Niwa 1-1, Ibikawa-cho, Ibi-gun, Gifu Prefecture Ibiden Ogaki Kita Plant F-term (reference) 4F202 AB13 AD04 AD12 AE04 AJ11 CA11 CB01 CB12 CD00 CD01 CD16 5E062 CC02 CD02 CE02 CE07 CF02

Claims (5)

[Claims] A cavity for supplying a resin molding material containing magnetic powder is formed therein, and a magnetic field is applied to the cavity from a predetermined direction when the resin molding material is supplied. A mold for a magnetic field molding machine, wherein a portion where magnetic lines of force forming the magnetic field are likely to leak out of the cavity is formed using a first material having a relatively small residual magnetic flux density, and other portions are formed. Characterized by using a second material having a relatively higher residual magnetic flux density than the first material. 2. The surface defining the cavity,
Where the plane perpendicular to the direction of the magnetic field belongs,
The mold for a magnetic field forming machine according to claim 1, wherein the mold is formed using the first material. 3. The method according to claim 1, wherein the residual magnetic flux density of the first material is less than the second magnetic flux density.
The mold for a magnetic field molding machine according to claim 1 or 2, wherein the residual magnetic flux density is 1/1000 or less of the residual magnetic flux density of the material. 4. The method according to claim 1, wherein the first material is a non-magnetic material,
4. The material according to claim 1, wherein said material is a magnetic material.
The mold for a magnetic field molding machine according to any one of the above. 5. When a width of the cavity along the direction of the magnetic field is T, a thickness of a portion formed by the first material in a direction orthogonal to the direction of the magnetic field is at least. The mold for a magnetic field molding machine according to any one of claims 1 to 4, wherein the mold is set to T / 2 or more.