JP2000200727A - Manufacture of magnet holding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture of the magnet molding which makes it possible to obtain a magnet molding such as a magnetic piece having a high magnetic force so that the orientation is not disordered and the size stability is improved. SOLUTION: For the manufacture, a molten mixture is cooled by a cooling means 14 which is in contact with or close to an orientation die 2 after being extruded through an orientation die 2 constituting a ferrule for extrusion molding which is constituted by arranging a temperature control means 13 within 20 mm from the tip of the orientation die 2. The orientation die 2 is thus used to obtain a magnet molding such as a magnetic piece 4 having a high magnetic force and the temperature control means 13 is arranged within 20 mm from the tip part of the orientation die 2 to eliminate the overcooling of the exit part of the orientation die 2 even if the cooling means 14 is arranged in contact with or nearby the orientation die 2, so the orientation become excellent although the size stability can be protected, so that a high magnetic force can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnet molded product such as a magnetic piece by extruding a molten mixture of a magnetic powder such as ferrite and a resin binder into a magnetic field.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic apparatus such as a copying machine or a printer, an electrostatic recording apparatus, or the like, a developing roller for visualizing an electrostatic latent image on a latent image holder such as a photosensitive drum is provided inside a rotating sleeve. A magnet roller formed of a resin magnet or a rubber magnet is disposed on the surface of the sleeve, and a magnetic developer (toner) carried on the surface of the sleeve is jumped onto the latent image holding member by a magnetic force characteristic of the magnet roller. Supplying toner to the surface of the image carrier,
A developing method for visualizing an electrostatic latent image is known. Conventionally,
The magnet roller is a pellet-shaped resin magnet composition or rubber magnet composition in which a magnetic powder such as ferrite is mixed with a thermoplastic resin such as nylon or polypropylene or a binder of rubber, using a mold around which a magnetic field is formed. It is manufactured by injection molding or extrusion molding to form a roller and magnetize it to desired magnetic properties.

However, with the recent development of electrophotographic apparatuses and the like, there is a tendency that a more complicated magnetic force pattern is required for the magnet roller, but the magnetic force pattern that can be designed with the conventional magnet roller is limited. Yes, we cannot fully meet this demand. Therefore, conventionally, in order to increase the degree of freedom of the magnetic force pattern of the magnet roller, a plurality of magnetic pieces magnetized with magnetic poles corresponding to the target magnetic force pattern are formed with the resin magnet or the rubber magnet, and these are formed on the shaft. 2. Description of the Related Art A desired magnetic force pattern is formed by pasting around a periphery. In such a magnetic piece, it is technically difficult to obtain a high magnetic force piece having a surface magnetic force of 1050 gauss or more by extrusion in a magnetic field, and it is generally manufactured by injection molding in a magnetic field. In particular, when a magnetic roller is formed by joining a plurality of magnetic pieces, it is more difficult because the constituent pieces are relatively thin.

[0004] In general, as a method of manufacturing a magnetic piece, injection molding and extrusion molding in which a magnetic field generating means is provided are known. However, from the viewpoints of economy and workability such as reduction in die cost, the latter is preferred. Extrusion molding is widely adopted, for example, after extruding a molten mixture of a magnetic powder and a resin binder through an orientation die provided with a magnetic field generating means,
The magnetic piece is manufactured by cutting to a predetermined length. In order to increase the magnetic force of the magnetic piece as described above, it is necessary to orient magnetic powder such as ferrite in a form suitable for the purpose. Therefore, by arranging a concentrated magnetic pole and an opposing magnetic pole facing the concentrated magnetic pole in the alignment die,
The magnetic powder in the molten resin mixture is oriented in a target direction in a magnetic field formed between these magnetic poles, and a high magnetic force can be applied to a specific portion on the surface of the magnetic piece.

[0005]

However, a magnet molded product such as a magnetic piece extruded from an orientation die has a high resin temperature and is in a state where plasticization is possible even though it is slight, so that the magnetic powder is mainly used for mutual interaction between magnetic powders. Shape change and magnetic force reduction due to action or interaction between the magnetic powder and an external magnetic field are inevitable. Therefore, in order to solve such a problem, it is conceivable to cool the molded product in the vicinity of the exit of the orientation die. However, with the mere provision of cooling means, the exit of the orientation die is excessively cooled. Then, in an extreme case, the molded product is solidified at the outlet portion, and there is a possibility that the molding itself is obstructed.

Accordingly, the present invention solves the above-mentioned problems in the conventional method for manufacturing a magnet molded product, and converts a magnet molded product such as a magnetic piece having a high magnetic force into a state in which orientation is not disturbed and dimensional stability is improved. It is an object of the present invention to provide a method for producing a magnet molded product that can be obtained by using the method described above.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention provides a method of manufacturing a magnet molded product by extruding a molten mixture of a magnetic powder and a resin binder through an orientation die provided with a magnetic field generating means. In the method, a space for temperature control was directly secured inside the alignment die.
A concentrated magnetic pole and an opposing magnetic pole facing the concentrated magnetic pole are incorporated in the alignment die. Providing a space here has a great effect on magnetic field formation. In other words, providing a space in this part, which corresponds to almost the entire main part on the piece magnetization, increases the reluctance of the magnetic circuit and greatly impairs the magnetic field in the cavity, which is clearly contrary to the common sense of the prior art. For example, the method disclosed in Japanese Patent Laid-Open No.
The invention aims at preventing the magnetic particles from rotating due to the shearing force due to the velocity gradient generated between the flow center portion and the die wall surface portion in the die cavity portion and consequently disturbing the orientation. It has been proposed to use a die having a structure in which part or all of the cross section extends in the extrusion direction. That is, it is understood that the reference conventional example presupposes magnetization inside the die. However, as long as there is a sufficient alignment magnetic field at the exit of the die as the main part of the piece magnetization, the magnetization of the piece can be sufficiently achieved, and providing a space inside the alignment die has a very large effect on the magnetic field formation inside the cavity. The temperature control means is arranged within 20 mm from the tip of the orientation die based on the knowledge that it is possible to minimize the influence on the tip of the die by a normal magnetic circuit design technique. It has been developed to extrude the molten mixture through an orientation die constituting a die for extrusion molding and then cool the molten mixture by a cooling means in contact with or close to the orientation die. Further, in the present invention, in the orientation die, a magnetic metal for orienting the magnetic powder may be disposed between the temperature control means and a concentrated magnetic pole side in a magnetic pole constituting an extrusion die. It is a feature. Further, the present invention is characterized in that the cooling means is formed in a cylindrical shape into which a refrigerant is injected, and cools the molten mixture. Further, the present invention is characterized in that the temperature control means adjusts the temperature of the alignment die by circulating oil through the alignment die. Further, the present invention is characterized in that the temperature control means adjusts the temperature of the alignment die by disposing a heater on the alignment die. Further, in the invention, it is preferable that the heater includes a first heater provided at least at a tip end portion of the orientation die, and a second heater provided in a direction opposite to the first heater. It is a feature. Further, the present invention is characterized in that the magnet molded product is a magnetic piece for a magnetic roller, and these are used as means for solving the problem.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view of a first embodiment of a method of manufacturing a magnet molded product according to the present invention. FIG. 1 (A) is an overall sectional view of an extruder, FIG. 1 (B) is a side view of an orientation die, FIG.
1C is a sectional view taken along line AA of FIG. 1B, and FIG.
FIG. 3B is a cross-sectional view taken along the line BB of FIG. FIG. 2 is a side sectional view and a front view of a magnetic roller as a product, and FIG. 3 is an explanatory diagram of magnetization of a magnetic piece near an exit of an orientation die. According to the present invention, as shown in FIG. 1 of the first embodiment, a magnet mixture 4 is extruded by extruding a molten mixture 11 of a magnetic powder and a resin binder through an orientation die 2 provided with a magnetic field generating means. In the method for producing a magnet molded product to be obtained, a magnetic metal for forming a ferrule for extrusion molding and disposed in the magnetic field generating means 3A, 3B and for orienting the magnetic powder in the molten mixture 11 at the outlet of the product cavity 8 5, the molten mixture 11 is extruded through an orientation die 2 in which a concentrated portion 5B of 5 is arranged, and a temperature control means 13 is provided within 20 mm from a tip end of the orientation die 2 to constitute a die for extrusion molding. After extruding the molten mixture 11 through the orientation die 2
The magnet molding 4 which is the molten mixture is cooled by cooling means 14 which comes into contact with or close to the orientation die 2.

The position of the concentrated portion 5B in the extrusion direction of the molten mixture is arranged near the outlet as shown in FIG. 1B, and the distance from the outlet is particularly limited. However, it is preferably 10 mm or less. Also, the overall length of the alignment die is not particularly limited,
It is preferably about 10 to 150 mm. It is sufficient that the length of the concentrated portion 5B of the magnetic metal in the extrusion direction is about 1/3 to 1/50 (about 3 mm) of the length of the alignment die. The width of the concentrated portion 5B is a matter determined in reverse from the magnetic force pattern required for the magnetic roller, and is not an essential component of the present invention.

As shown in FIG. 1 (A), a molten mixture 11 of a magnetic powder and a resin binder, which passes through an orientation die 2 as a die for extrusion molding to become a magnetic piece 4 as a product, is placed in a melting cylinder 1. After flowing down, the magnetic field generating means 3, which is a magnetic field generating device for alignment, is placed above and below the alignment die 2, for example, by a magnetic block 1 so as to be extruded in a magnetic field through a diaphragm 15 connected via a breaker plate 16.
2 are provided. The magnetic field generating means 3A for the concentrated magnetic pole is located above, and the magnetic field generating means 3B for the opposite magnetic pole is located below. The magnetic block 12, the magnetic metal upper die 5 (particularly the magnetic metal concentrated part 5B 3), a high surface magnetic force is obtained at the position P as shown in FIG. 3B by the concentrated magnetic force lines directed to the magnetic metal lower mold 6, the magnetic block 12, and the magnetic field generating means 3A. At this time, generally, in order to obtain a high surface magnetic force, high concentrated magnetic force lines from the magnetic field generating means 3B for the opposed magnetic pole to the magnetic field generating means 3A for the concentrated magnetic pole are required. The orientation die 2 as a die used for extrusion molding is drawn, has a high magnetization,
In the present invention, the size becomes large due to the necessity of satisfying multiple functions such as orientation and shape stabilization, and the size of the electromagnetic piece which is an example of the magnetic pole used for forming the magnetic field becomes large. As shown in FIG. 1 (B), the product cavity is formed only in the vicinity of the exit portion on the magnetic field generating means 3A side for the concentrated magnetic pole of the orientation die 2 arranged in the magnetic field generating means 3A and 3B by forming an extrusion die. 8, the narrow concentrated portion 5B of the magnetic metal 5 is disposed adjacent to the position where the high surface magnetic force should be obtained (corresponding to the position P in FIG. 3B). Multiple functions such as stabilization of orientation and shape can be satisfied.

[0011] To explain the improvement and stabilization of the orientation, a magnetic metal tip for forming a magnetic field is provided at the outlet to form a main part of the piece magnetization. The rotation of the magnetic particles due to the shearing force due to the velocity gradient generated between the die wall and the orientation of the magnetic particles, that is, the disturbance of the orientation can be prevented, and the magnetic force can be increased. In addition, regarding the stabilization of the shape, the raw material composition used for producing the magnetic piece contains a very high proportion of magnetic powder and differs from the general extruded material in flow characteristics. Reflecting this, it is common sense that the land at the tip of the base, which is necessary for stabilizing the shape, is not only unnecessary, but also rather harmful in the production of high magnetic force magnetic rollers as described above. . According to the present invention, cooling at the outlet of the base can be taken into account, and dimensional stability and magnetic force can be improved.

As shown in FIG. 1B, the orientation die 2 has a predetermined length, and a product cavity 8 defined by a magnetic metal upper die 5 and a magnetic metal lower die 6 has a magnetic metal lower die. 6. Left and right non-magnetic metals 7A and 7B are disposed between the magnetic metal upper mold 5 and the product cavity 8, and the magnetic metal concentrated portion 5B is adjacent to a position where a high surface magnetic force is to be obtained in the product cavity 8. The nonmagnetic metals 7A and 7B are divided at this portion so as to be arranged. High magnetic lines of force are directed from the magnetic metal lower mold 6 to the magnetic metal upper mold 5 through the concentrating portion 5B, and the magnetic force is concentrated to obtain a high surface magnetic force.

Although the cross-sectional shape of the product cavity 8 in the alignment die 2 shown in FIG. 1B is formed substantially rectangular, in actuality, as shown in FIGS. 4 is a plurality of magnetic drum pieces 4A
(N pole), 4B (S pole), 4C (N pole) and 4D (S pole)
The poles are joined around a shaft 9 to form a magnetic roller 10, and thus the cross-sectional shape of the magnetic piece 4, that is, the product cavity 8, forms a sector shape. Although the magnetic piece as an example of the magnet molded product has been described here, a cylindrical magnetic body can be formed. Further, the molten mixture 11 of the magnetic powder and the resin binder is melted,
5, the molten mixture 1, which is caused to flow down to the orientation die 2, is melted by the extruder (not shown). Temperature (120 °
(Before and after), flow down at an appropriate flow rate (before and after cooling), and in the middle of the sliding material, for example, the molten mixture 1 at the molding temperature.
A thermoplastic resin such as an olefin-based resin having a higher fluidity than 1, or a polyolefin-based wax or the like can be mixed and sent to the alignment die 2.

The most characteristic feature of the present invention is that the alignment die 2
Because the molten mixture, which is a magnet molded product that becomes the magnetic piece 4 extruded from the magnet, is still at a high temperature and still in a slightly plasticizable state, the interaction between the magnetic powders or the external magnetic field In order to avoid a change in shape and a decrease in magnetic force due to the interaction with the die, excessive cooling of the tip of the alignment die by the cooling means 14 disposed in contact with or close to the outlet of the alignment die 2 is effectively prevented. What is required is that a space for temperature control is secured directly inside the alignment die. As shown in FIG.
With respect to the orientation die 2 set to about 50 mm (preferably about 60 mm), the wall thickness t from the tip of the orientation die to 20 mm or less (preferably about 0.5 to 10 mm). By disposing the magnet, it is possible to secure a proper orientation by the magnetic metal concentrated portion 5B under a proper temperature and a proper viscosity, and to increase the magnetic force of the magnet molded product, and by appropriate cooling without excessively falling. By extruding from the orientation die 2, it is possible to obtain a magnet molded product without impairing the appearance thereof in a state where the orientation is not disordered and the dimensional stability is improved.

In the present embodiment, as shown in FIG. 1 (A), a circulation path for heated oil is provided around a product cavity 8 which is bored through the axis of the orientation die 2. Thus, the temperature control means 13 is configured. By circulating the heated oil supplied from the temperature controller 19 installed outside the extruder through the magnetic block 12, the molten mixture as a magnet molded product that becomes the magnetic piece 4 flowing down in the product cavity 8 is formed. The temperature of the alignment die 2 is adjusted to adjust the temperature. The cooling means 14 provided in contact with or close to the outlet of the alignment die 2 is a cooling space into which a coolant (cooling water) from a water cooling pump 20 or the like is injected into a cylindrical main body 14A made of a fluorine resin or the like. 14B,
The molten mixture, which is a magnet molding extruded from the outlet of the orientation die 2, is cooled.

FIG. 4 shows a second embodiment of the method for producing a magnet molded product according to the present invention. FIG. 4 (A) is an overall sectional view of an extruder, and FIGS. 4 (B) and 4 (C) show orientations. FIG. 4 (D) is a side view of the die before processing the temperature control means and a cross-sectional view of the die taken along the line CC.
(E) is a side surface after temperature control means processing and its DD sectional view. In the present embodiment, as the temperature control means 13 in the orientation die 2, a heater of an appropriate type is provided in the orientation die 2, and the temperature of the orientation die 2 is adjusted by the heater. Is what you do. FIG.
(B) As shown in (C), the alignment die 2 has a predetermined length, and the product cavity 8 defined by the magnetic metal upper die 5 and the magnetic metal lower die 6 is formed in the magnetic metal lower die 6. Left and right non-magnetic metals 7A and 7B are disposed between the magnetic metal upper die 5 and the product cavity 8, and the magnetic metal concentrated portion 5B is located at a position where a high surface magnetic force is to be obtained in the product cavity 8. Are located adjacent to each other. That is, the concentrated portion 5B of the magnetic metal is formed over the entire length in the length direction. 4D and 4E, the temperature control means 13 is formed by leaving the portion of the wall thickness t from the outlet of the tip of the alignment die 2, thereby forming the concentrated portion 5B of the magnetic metal.
Are formed with the wall thickness t remaining. Such temperature control means 1 in the alignment die 2
3 is formed in the same manner as in the example of FIG. 1 described above and the example of FIG. 5 described later.

FIG. 5 shows a third embodiment of the method for producing a molded magnet according to the present invention. FIG. 5 (A) is an overall sectional view of an extruder, and FIG. 5 (B) is a side view of an orientation die. FIG. 5
5C is a sectional view taken along line E-E of FIG. 5B, and FIG.
FIG. 3B is a cross-sectional view taken along line FF of FIG. 1 (note that a magnetic metal and a nonmagnetic metal are omitted here). In the present embodiment, the heater in the second embodiment is at least the orientation die 2 as the temperature control means 13 in the orientation die 2.
Heater (tip heater) 17 provided at the tip of the heater
And a second heater (entire heater) 18 disposed in a direction opposite to the direction in which the first heater 17 is pushed out. In the case of this embodiment mode, FIG.
As shown in FIG. 2, the first heater 17 is formed at a portion of the wall thickness t from the outlet of the tip of the orientation die 2, and
A concentrated portion 5B of the magnetic metal is disposed at the wall thickness t. The portion located between the first heater 17 and the second heater 18 may be provided with the concentrated portion 5B of the magnetic metal left, or the concentrated portion 5B of the magnetic metal does not exist. Is also good.

The composition for resin magnetism, which is the molten mixture 11, is obtained by mixing and dispersing magnetic powder and the like in a resin binder. As the binder resin, a resin generally used as a binder for a resin magnet can be used. Specifically, polyamide resin, polypropylene, polyethylene, polystyrene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT),
Various thermoplastic resins such as polyphenylene sulfide (PPS), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate (EEA), ethylene-vinyl alcohol copolymer (EVOH) alone or
These can be used in combination.

As the magnetic powder mixed and dispersed in the resin binder, a known magnetic powder conventionally used for a composition for a resin magnet of a magnetic roller or the like can be used. , Ba ferrite and other ferrite magnetic powders, Sm-Co alloys, Nd-Fe-
B-alloys, Ce-Co alloys and other magnetic earth-based alloy powders can be exemplified. This magnetic powder can be subjected to a known pretreatment as necessary. For example, a pretreatment using a coupling agent can be performed and used in the present invention. In particular, in the present invention, it is preferable to perform a coupling treatment using a silane coupling agent or a titanate coupling agent. By using a magnetic powder subjected to a proper coupling treatment, the melt fluidity at the time of high filling can be more effectively improved.

As the silane coupling agent, γ-
Aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ
-Aminopropyltrimethoxysilane, ureidopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, methyltriethoxysilane, methyltrimethoxysilane And γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane Etc. are particularly preferably used.

Examples of the titanate coupling agent include isopropyl bis (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, isopropyl triisostearoyl titanate, and diisopropyl bis (dioctyl pyrophosphate) titanate. , Tetraisopropylbis (dioctylphosphite) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate,
Bis (dioctyl pyrophosphate) oxyacetate titanate, bis (dioctyl pyrophosphate)
Ethylene titanate and the like are exemplified, and among them, isopropyl bis (dioctyl pyrophosphate) titanate is particularly preferably used.

The magnetic powder used in the present invention is not particularly limited, but from the viewpoint of the melt fluidity of the obtained resin magnet composition, the orientation of the magnetic powder, the filling ratio, and the like, the average particle diameter is 0%. It is preferably from 0.5 to 100 μm, particularly preferably from 0.7 to 20 μm. In the composition for a resin magnet of the present invention,
In addition to the resin binder component, a compound having a magnetic powder and a hindered phenol resin, a filler having a large reinforcing effect such as mica, whisker or talc, carbon fiber, or glass fiber does not disturb the spirit of the present invention. It can be appropriately added within the range. That is, the magnetic force required for the molded product is relatively low, and when the filling amount of the magnetic powder is small, the rigidity of the molded product tends to be low. In that case, mica, whisker, etc. A filler can be added to reinforce the molded article. As the filler suitably used in the present invention, mica or whiskers are preferable. As the whiskers, non-oxidized whiskers made of silicon carbide and silicon nitride, ZnO, MgO, Ti
Metal oxide whiskers composed of O ₂ , SnO ₂ , Al ₂ O _{3 and the} like, and double oxide whiskers composed of potassium titanate, aluminum borate, basic magnesium sulfate and the like, among them, among these, A double oxide whisker is particularly preferably used because it can be easily combined with plastic. When these fillers are used, the mixing ratio is not particularly limited, but is usually about 2 to 30% by weight, particularly about 5 to 20% by weight of the whole composition for resin magnets. In addition, additives other than the above-mentioned fillers may be added to the composition for a resin magnet of the present invention without departing from the spirit of the present invention.

[0023]

FIG. 6 is a table showing the results of an example and a comparative example of the method for producing a magnet molded product according to the present invention. <Example 1> A magnetic piece was manufactured under the following conditions. Extrusion speed at the time of melting of the resin magnet composition is 1.5 m / min, temperature of the melting cylinder 1 is 120 ° C., temperature of the orientation die 2 is 11
5 ° C., width 1 of magnetic metal concentrated portion 5B in FIG. 1 (C)
mm, the applied current to the magnetic pole is 10 A, and the generated magnetic field is 13500
0 gauss, water cooling as cooling means, water volume 50m
1 / min, the surface magnetic force of the magnetic piece 4 obtained by disposing the temperature control means by oil circulation from the outlet of the orientation die to the wall thickness t = 10 mm (see FIG. 1A) is 1170 gauss, The appearance as a magnet molded product was also good. <Embodiment 2> Under the conditions in the embodiment 1, the temperature control means by oil circulation was changed from the outlet of the orientation die to the wall thickness t =
The surface magnetic force of the magnetic piece 4 obtained by arranging it up to 2 mm was 1180 gauss, and the external shape as a magnet molded product was also good. <Embodiment 3> The surface magnetic force of the obtained magnetic piece 4 is 1160 gauss even if the amount of water as the cooling means is reduced to 25 ml / min under the conditions in the embodiment 2, and the magnetic molded article 4 The external shape was also good. <Embodiment 4> Under the conditions in the embodiment 2, the surface magnetic force of the magnetic piece 4 obtained by employing the tip heater (see FIG. 5A) as the temperature control means is 1180 gauss,
The appearance as a magnet molded product was also good.

<Comparative Example 1> When the cooling means was not provided in Example 1, the surface magnetic force of the magnetic piece was 1130 gauss. <Comparative Example 2> When the cooling means was not provided for Examples 2 and 3, the surface magnetic force of the magnetic piece was 1130 Gauss. <Comparative Example 3> In contrast to Examples 1 and 2, when the temperature control means by oil circulation is provided only from the outlet of the orientation die to the wall thickness t = 30 mm, the temperature control means is excessively affected by the cooling means,
The surface magnetic force of the obtained magnetic piece was not measurable, and it was impossible to produce a magnet molded product. <Comparative Example 4> With respect to Comparative Example 3, when no cooling means was provided, the surface magnetic force of the obtained magnetic piece was 1130 gauss. Comparative Example 5 The surface magnetic force of a magnetic piece obtained by a conventional method using no cooling means or temperature control means was 1130.
Gauss was.

Although the embodiments of the present invention have been described in detail, within the scope of the present invention, the type of the temperature control means, the type of the cooling means, the circulation form of the medium in them, the shape of the melting cylinder, Form, extrusion form, heat retention form, mixing and mixing of molten mixture, magnetic pole arrangement form, orientation die shape and its shape, cross section of product cavity, etc. The installation form and the like can be appropriately adopted.

[0026]

As described above in detail, according to the present invention, a magnet mixture is obtained by extruding a molten mixture of a magnetic powder and a resin binder through an orientation die provided with a magnetic field generating means. In the method for producing a magnet molded product, the molten mixture is extruded through an orientation die constituting an extrusion die having a temperature control means disposed within 20 mm from the tip of the orientation die, and then contacted with the orientation die. Alternatively, since the molten mixture is cooled by a cooling means provided close to the die, a high magnetic force can be obtained by using an orientation die which constitutes a die for extrusion molding by disposing a temperature control means on the orientation die. A magnetic molded product such as a magnetic piece can be obtained, and the temperature control means is disposed within 20 mm from the tip of the orientation die, so that the temperature control means does not come into contact with or close to the orientation die. Even when provided with cooling means, there is no the outlet portion of the orientation die is excessively cooled, high magnetic force can be obtained becomes good in orientation despite those dimensional stability can be ensured.

The cooling means is formed in a cylindrical shape into which a refrigerant is injected and cools the molten mixture, thereby enabling a stable supply of the refrigerant from the outside.
Cooling can be performed under certain conditions. Furthermore, if the temperature control means adjusts the temperature of the orientation die by circulating oil in the orientation die, it enables stable supply and circulation of a heating medium from the outside, and under certain conditions. Temperature control. Furthermore, if the temperature adjusting means adjusts the temperature of the alignment die by disposing a heater on the alignment die, it is possible to perform electrical precision control and perform stable temperature control of the alignment die. Further, if the heater is constituted by at least a first heater disposed at a tip end portion of the orientation die, and a second heater disposed in a direction opposite to the extrusion of the first heater, By appropriately controlling the temperatures of these first and second heaters individually, it is possible to skillfully secure the orientation and size and shape of the magnetic powder in the molten mixture.

In addition, there is no need to provide a concentrated portion of the magnetic metal on the concentrated magnetic pole side over the entire length of the alignment die. Therefore, an electromagnetic piece, which is an example of a magnetic pole used for forming a magnetic field, is small and has a small applied current. Even with a small current, it is possible to satisfy various functions such as drawing, high magnetization, orientation, shape stabilization, etc., and it has conventionally been a common sense countermeasure method for shape stabilization to eliminate the curvature. It was not necessary to take a long land portion at the exit of the orientation die, which is rather harmful to the manufacture of the magnetic roller. Even if the electromagnet which is an example of the orientation die and the magnetic poles is small, it is sufficient. Since a strong surface magnetic force is obtained, the applied current can be reduced, and a low-cost manufacturing method and apparatus of a magnet molded product can be obtained. As described above, according to the present invention, there is provided a method of manufacturing a magnet molded product that can obtain a magnet molded product such as a magnetic piece having a high magnetic force without disturbance in orientation and with improved dimensional stability.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a first embodiment of a method for producing a molded magnet according to the present invention, wherein FIG.
FIG. 1B is a side view of the alignment die, and FIG.
FIG. 1B is a cross-sectional view taken along the line AA of FIG.
It is B sectional drawing.

FIG. 2 is a side sectional view and a front view of a magnetic roller as a product.

FIG. 3 is an explanatory diagram of magnetization of a magnetic piece near an exit of an alignment die.

FIG. 4 is an explanatory view showing a second embodiment of the method for producing a magnet molded product of the present invention.

FIG. 5 is an explanatory view showing a third embodiment of the method for producing a magnet molded product of the present invention.

FIG. 6 is a table showing the results of Examples and Comparative Examples of the method for producing a magnet molded product of the present invention.

[Explanation of symbols]

 Reference Signs List 1 melting cylinder 2 orientation die 3 magnetic pole 3A magnetic field generating means for concentrated magnetic pole 3B magnetic field generating means for opposed magnetic pole 4 magnetic piece 4A to 4D magnetic drum piece 5 magnetic metal upper die 5B magnetic metal concentrated portion 6 magnetic metal lower die 7A left Non-magnetic metal 7B Right non-magnetic metal 8 Product cavity 9 Shaft 10 Magnetic roller 11 Molten mixture (molten resin magnet material) 12 Magnetic block 13 Temperature control means 14 Cooling means 14A Main body 14B Cooling space 15 Restrictor 16 Breaker plate 17 First heater (Tip heater) 18 Second jetter (Whole heater) 19 Temperature controller 20 Water cooling pump t Wall thickness

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B29K 103: 06 B29L 7:00 F term (Reference) 4F207 AA49 AE04 AH33 KA01 KA07 KA17 KK64 KW50 4F213 AA49 AE04 AH33 WA06 WA23 WA84 WB01 WF06 5E062 CC01 CD02 CD05 CE03 CE07 CF02 CG01

Claims (7)

[Claims] 1. A method for producing a magnet molded product by extruding a molten mixture of a magnetic powder and a resin binder through an orientation die provided with a magnetic field generating means, wherein a magnet molded product is obtained. After extruding the molten mixture through an orientation die constituting an extrusion die having a temperature control means provided within 20 mm, the molten mixture is cooled by cooling means in contact with or close to the orientation die. A method for producing a magnet molded product, characterized in that: 2. The method according to claim 1, wherein a magnetic metal for orienting the magnetic powder in the orientation die is disposed between the temperature control means and a concentrated magnetic pole side in a magnetic pole constituting a die for extrusion molding. The method for producing a magnet molded product according to claim 1, wherein: 3. The method according to claim 1, wherein the cooling unit is formed in a cylindrical shape into which a refrigerant is injected to cool the molten mixture. 4. The production of a magnet molded product according to claim 1, wherein the temperature control means adjusts the temperature of the orientation die by circulating oil through the orientation die. Method. 5. The magnet molded product according to claim 1, wherein the temperature adjusting means adjusts the temperature of the orientation die by disposing a heater on the orientation die. Production method. 6. The apparatus according to claim 1, wherein the heater comprises at least a first heater disposed at a tip end of the orientation die, and a second heater disposed in a direction opposite to the first heater. A method for producing a magnet molded product according to claim 5, characterized in that: 7. The method of manufacturing a magnet molded product according to claim 1, wherein the magnet molded product is a magnetic piece for a magnetic roller.