JP2018064111A - Method for manufacturing compressed bond magnet with case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a compressed bond magnet with a case by which the compressed bond magnet with the case and having a high magnetic property, high corrosion resistance and high endurance strength can be manufactured with high productivity at a low cost.SOLUTION: A method for manufacturing a compressed bond magnet with a case which includes a compressed bond magnet including rare earth magnet powder such as isotropic Nd-Fe-B magnet powder and a resin binder of thermosetting resin, a case for inserting the compressed bond magnet, and a sealing member, provided that the compressed bond magnet is sealed off by the sealing member and the case, comprises: a step (a) for compression-molding a mixture including the rare earth magnet powder and the resin binder to form a powder compact; a step (b) for inserting the powder compact before curing the resin binder in the case; and a sealing step (c) for fixing the sealing member to an insertion opening by e.g. curing the uncured thermosetting resin (sealing member) applied to an insertion opening of the powder compact, and the uncured resin binder in the powder compact.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a compression bonded magnet with a case used for a sensor that detects an angle in a non-contact manner, and particularly in contact with a fluid such as water, oil, exhaust gas, and the like in a corrosive environment that requires corrosion resistance. The present invention relates to a method of manufacturing a compression bonded magnet with a case to be used.

  Bonded magnets formed by bonding magnetic powders such as rare earth alloys with a resin binder are inferior in magnetic properties to binderless sintered magnets because they contain resin binders, but they can be easily processed into arbitrary shapes and their dimensions Since it is excellent in accuracy, it is used in various applications. For example, as a sensor application that detects angles without contact, in the automotive field, water pump flow path switching valves, oil pumps, fuel for efficient cooling of engines, inverters, batteries, etc. of HEV and EV vehicles It is used as a sensor magnet for detecting the opening / closing angle of a pump or the like, and in the industrial machine field, it is used as a sensor magnet for detecting an absolute angle in a robot.

  As a bonded magnet, a mixture of magnet powder and a resin binder such as a thermosetting epoxy resin filled in a mold and compression-molded (compressed bonded magnet), and a mixture of magnet powder and a thermoplastic resin binder are used. Some are pelletized and injection molded using this. Since the compression bonded magnet can increase the amount of magnet powder as compared with that obtained by injection molding, high magnetic properties can be achieved.

  When the rare earth magnet powder is used for a bonded magnet, it contains iron or rare earth, so there is a problem that rust penetrates into the inside or there is a risk of deterioration of magnetic properties due to oxidative corrosion. This is particularly noticeable in a corrosive environment in contact with a fluid such as water. For this reason, in the compression bond magnet, the above-mentioned problem is dealt with by forming a resin coating film on the exposed surface of the magnet by, for example, electrodeposition coating, electrostatic coating, spray coating or the like.

  Conventionally, a method for producing a compression bonded magnet in which a rust-proof thermosetting film is formed on the surface of a rare earth magnet by an immersion method has been proposed (see Patent Document 1). In this manufacturing method, immersion, drying and curing are repeated 2 to 6 times to form a 0.005 mm to 0.05 mm rust-proof thermosetting film on the magnet surface while impregnating the resin in the gap in the magnet. .

JP 2002-260943 A

  In recent years, small sensors used in environments where corrosion resistance is required due to contact with fluids such as water, oil, exhaust gas, etc. have further improved magnetic properties while ensuring excellent corrosion resistance and moldability. Is desired. However, although conventional compression bonded magnets including Patent Document 1 can increase the amount of magnet powder as compared with that by injection molding, the amount of magnet powder is about 83% at maximum in volume ratio with respect to the whole magnet. In some cases, it is difficult to meet the above requirements with the magnetic properties of the compression bonded magnet. Simply reducing the amount of resin binder to improve the magnetic properties and increasing the amount of magnet powder beyond the normal limit (83%), the durability strength and adhesion of the compression molded magnet itself during use The strength may not be maintained.

  On the other hand, it is conceivable to use binderless magnets (sintered magnets) with higher magnetic properties instead of bonded magnets, but binderless magnets are compression molding of rare earth alloys and other magnet powders under ultra high pressure. After that, a process of performing heat treatment in a vacuum furnace at a high temperature (for example, 500 ° C. or higher) is necessary, and the manufacturing cost is higher than that of a compression bonded magnet. In addition, the magnetic properties may be deteriorated by the high-temperature heat treatment. Furthermore, since it is used in a corrosion-resistant environment, it is necessary to separately form the above-mentioned resin coating film on the surface of the rare earth magnet, or a metal coating film by electroplating or metal deposition.

  In the manufacturing method of Patent Document 1, the formation of the rust-proof thermosetting film is performed in a separate process after the magnet is formed, and the dipping process is repeated a plurality of times. Inferior manufacturing costs also increase.

  In addition, by using an anisotropic magnet as the type of rare earth magnet powder, it is possible to achieve higher magnetic properties than when using an isotropic magnet. However, an anisotropic magnet requires magnetic field orientation molding by a magnetic field molding machine and is manufactured. Cost increases.

  The present invention has been made to address such problems, and a compression bond magnet with a case capable of manufacturing a compression bond magnet with a case having high magnetic properties, high corrosion resistance, and high durability strength at high productivity and at low cost. It aims at providing the manufacturing method of a magnet.

  A manufacturing method of a compression bonded magnet with a case of the present invention comprises a compression bonded magnet including a rare earth magnet powder and a thermosetting resin resin binder, a case for inserting the compression bonded magnet, and a sealing member. A method of manufacturing a compression bonded magnet with a case in which the compression bonded magnet is sealed with the sealing member and the case, wherein the mixture containing the rare earth magnet powder and the resin binder is compression molded and compressed. Forming a green compact, forming a green compact after the resin binder is cured or a green compact before the resin binder is cured into the case, and inserting the green compact into the case And a sealing step of fixing a sealing member to the opening.

  The green compact insertion step is a step in which the resin binder inserts the compact before being cured into the case, and the sealing step is performed after the curing in the insertion opening of the compact in the case after the curing. The thermosetting resin to be a member is applied so as to cover the non-contact portion of the compact with the case while partly contacting the case, and the thermosetting resin and the resin binder have a heat curing start temperature or higher. In the process of curing the thermosetting resin and fixing the sealing member to the case, and curing the resin binder in the green compact to form the compression bonded magnet. It is characterized by that.

  The case is made of a non-magnetic material, the green compact and the compression bonded magnet are substantially cylindrical, and are magnetized in the radial direction of the cylinder, covering the outer peripheral surface side and the bottom surface side of the cylinder. Is arranged, and the sealing member is arranged on the upper surface side of the cylinder.

  The case is made of a non-magnetic material, the green compact and the compression bonded magnet are substantially cylindrical, and are magnetized in the radial direction of the cylinder, covering the outer peripheral surface side and the bottom surface side of the cylinder. The sealing member is disposed on the upper surface side of the cylinder, and the green compact has a step portion that is in non-contact with the case at least on the cylinder upper surface side end portion of the outer peripheral surface thereof. In the stopping step, the step portion is filled with the thermosetting resin, and a part of the sealing member is formed in the step portion.

  The heat treatment in the sealing step is performed at a temperature of 200 ° C. or lower and under normal pressure.

  The rare earth magnet powder is an isotropic Nd—Fe—B magnet powder, and the magnet powder is contained in a volume ratio of 85 to 90% with respect to the whole compression bonded magnet.

  A manufacturing method of a compression bonded magnet with a case of the present invention includes a compression bonded magnet including a rare earth magnet powder and a thermosetting resin resin binder, a case for inserting the compression bonded magnet, and a sealing member. A method for producing a compression-bonded magnet with a case in which the compression-bonded magnet is sealed with a sealing member and a case, and (a) a pressure at which a compact including a rare earth magnet powder and a resin binder is compression-molded to form a compact. A powder molding step, (b) a green compact after the resin binder is cured or a green compact before the resin binder is cured into the case, and (c) at the insertion opening of the compact in the case And a sealing process for fixing the sealing member, so that the compression bonded magnet can be completely sealed inside the case, has excellent corrosion resistance, and in a corrosive environment that directly contacts water, oil, exhaust gas, etc. Even so Case with compressed bonded magnet having high available corrosion resistance suitable is obtained. In addition, since the compression bond magnet itself does not require high durability due to the sealing structure, it is possible to reduce the amount of the resin binder and increase the amount of rare earth magnet powder compared to the normal compression bond magnet. A compression bonded magnet with a case having magnetic properties is obtained. Furthermore, even when a compression bonded magnet with a small amount of resin binder is employed, the above-described sealing structure can provide a compression bonded magnet with a case that has excellent durability as a whole in combination with the case and the sealing member.

  The green compact insertion step is a step of inserting the compact before the resin binder is cured into the case, and the sealing step is thermosetting that becomes a sealing member after curing at the insertion opening of the compact of the case. The resin is applied so as to cover the non-contact part of the compact with the case while partly contacting the case, and the thermosetting resin is cured by heat treatment above the thermosetting temperature of the thermosetting resin and resin binder. The sealing member is fixed to the case and formed, and the resin binder in the green compact is cured to form the compression bond magnet. Therefore, the compression bond magnet and the sealing member are cured in the same process. Each can be done without having to do each alone. In addition, the conventional coating process for improving the corrosion resistance can be eliminated. For this reason, the manufacturing process and the processing cost can be greatly reduced, and a compression bonded magnet with a case can be manufactured with high productivity and low cost.

  Since a compression bonded magnet is used as the magnet, the heat treatment at the time of the thermosetting can be performed, for example, at a temperature of 200 ° C. or less and under normal pressure, and no heat treatment at a vacuum / high temperature is required, resulting in higher production. Manufacturing at low cost.

  The case is made of a non-magnetic material, the green compact and the compression bonded magnet are substantially cylindrical, and are magnetized in the radial direction of the cylinder, and the case is arranged to cover the outer peripheral surface side and the bottom surface side of the cylinder, Since the sealing member is disposed on the upper surface side of the cylinder, the case does not adversely affect the magnetic characteristics. In addition, the sensor sensitivity is not adversely affected while the sealing member is a thicker molded body than a normal coating film.

  Further, the green compact has a stepped portion that is not in contact with the case at least at the end of the outer peripheral surface of the cylindrical upper surface, and the stepped portion is filled with a thermosetting resin in the sealing step. Since a part of the sealing member is formed, the bonding area between the case and the sealing member is increased, the adhesive strength is excellent, and peeling can be prevented. In addition, the barrier property of the corrosive fluid is excellent.

  Since the rare earth magnet powder is an isotropic Nd-Fe-B magnet powder, it is a resource-rich and inexpensive material and does not require magnetic field orientation molding by an expensive magnetic field molding machine. Further reduction can be achieved. In addition, since the compression bonded magnet is completely hermetically sealed by the case and the sealing member by the above sealing structure, while using the isotropic Nd-Fe-B magnet powder containing iron and rare earth that are easily oxidized, A compression-bonded magnet with a case that can prevent deterioration of magnetic properties and rust due to corrosion can be obtained. Furthermore, since the magnet powder is contained in a volume ratio of 85 to 90% with respect to the whole compression bonded magnet, a compression bonded magnet with a case having high magnetic characteristics that cannot be obtained with a normal compression bonded magnet is obtained.

It is a manufacturing process flowchart of the compression bonded magnet with a case of this invention. It is a figure which shows an example of the manufacturing process of the compression bonded magnet with a case of this invention. It is the top view and sectional drawing which show an example of the compression bonded magnet with a case obtained with the manufacturing method of this invention. It is a schematic diagram of the direction of the magnetic force line of the compression bonded magnet with a case of FIG.

  The manufacturing method of the compression bonded magnet with a case of this invention is demonstrated based on FIG. 1 and FIG. FIG. 1 is a manufacturing process flow diagram of a compression bonded magnet with a case of the present invention, and FIG. 2 is a diagram showing an example of a specific manufacturing process. A manufacturing method of a compression bonded magnet with a case of the present invention includes a compression bonded magnet including a rare earth magnet powder and a thermosetting resin resin binder, a case for inserting the compression bonded magnet, and a sealing member. This is a method for manufacturing a compression bonded magnet with a case in which the bonded magnet is sealed with a sealing member and a case.

  This manufacturing method includes at least the following three steps (a) to (c). (A) a compact forming process in which a mixture containing a rare earth magnet powder and a resin binder is compression molded to form a compact, and (b) a compact after the resin binder is cured (completion as a compressed bond magnet). Product) or a compact for inserting a green compact before the resin binder is cured into a case, and (c) a sealing step for fixing a sealing member to the insertion opening of the compact in the case. . FIG. 1 and FIG. 2 show (c) in the sealing step, the compression bonded magnet is cured simultaneously with the curing of the sealing member made of a thermosetting resin. (C1) includes a coating step and (c2) a thermosetting step. Each step will be described below.

[(A) Powder compacting process]
A mixture containing the rare earth magnet powder and the resin binder is compression molded. For example, as shown in FIG. 2A, a mixture of a rare earth magnet powder and a thermosetting resin resin binder is placed in a die 6 and compressed with an upper punch 7 and a lower punch 8 to obtain a green compact 2. '(Before curing) is formed. The mixing of the rare earth magnet powder and the resin binder can be appropriately selected from a dry method or a wet method according to the type of the thermosetting resin of the resin binder, and is performed using a blender such as a blender or a kneader. Moreover, the molding die used in this compacting process should just be a metal mold | die which can apply the molding pressure of 490-980 MPa.

  In this invention, it is preferable to use the magnet in which rare earth magnet powder is contained by 85 to 90% by volume ratio with respect to the whole compression bond magnet as a compression bond magnet. The resin binder has a volume ratio of about 3 to 10% and a porosity of about 5 to 10%. These volume ratios are the volume ratios in the final compression bonded magnet obtained through compression molding (compact molding) of rare earth magnet powder and resin binder and curing of the resin binder by heat treatment, and the specific gravity of each material It is set by adjusting the blending weight of each material in consideration of the molding pressure at the time of compression molding, the porosity, and the like. In addition, the volume ratio of the magnet powder of the conventional compression bond magnet is about 83% at the maximum as described above, and usually the magnet powder is about 75 to 80% and the porosity is about 10% to 15%.

  The blending weight ratio of the rare earth magnet powder and the resin binder is, for example, 0.5 mass% or more and less than 2 mass% of the epoxy resin (including the curing agent) with respect to the total amount, and the remainder is the rare earth magnet powder. is there. By setting it as this range, the volume ratio (85-90%) shown by the said suitable range can be achieved. In a normal compression bonded magnet, the resin binder is blended in an amount of 2 to 3% by mass with respect to the total amount of the rare earth magnet powder and the resin binder. In addition to the resin binder and rare earth magnet powder, this compression bonded magnet contains a small amount of other compounding agents such as calcium stearate and boron nitride for the purpose of improving compression moldability within a range that does not affect the magnetic properties. You may go out.

  By setting the blending amount of the rare earth magnet powder to 85% by volume or more with respect to the whole compression bonded magnet, high magnetic properties can be obtained. Specifically, the high magnetic characteristics are excellent in maximum energy product, residual magnetic flux density, coercive force and the like. If the rare earth magnet powder is less than 85% by volume with respect to the entire compression bonded magnet, the desired magnetic properties may not be obtained. On the other hand, if it exceeds 90% by volume, the amount of the resin binder becomes relatively small, and there is a risk of damage during the green compact insertion process. The rare earth magnet powder is more preferably contained in a volume ratio of 85 to 88% with respect to the entire compression bonded magnet. By setting it as this suitable range, the characteristic which was compatible about the magnetic characteristic and material strength is acquired, and there exists an effect of the automation response | compatibility etc. in case press-fit of a compression bond magnet.

  As the rare earth magnet powder forming the green compact, any magnet powder that can be used for producing rare earth permanent magnets can be used. For example, Nd—Fe—B type, Sm—Co type magnet powder, etc. Is mentioned. Moreover, any of isotropic and anisotropy can be used. Among these, it is preferable to use Nd—Fe—B magnet powder because it is made of a resource-rich and inexpensive material and has high magnetic properties. In addition, it is particularly preferable to use isotropic Nd—Fe—B magnet powder because magnetic field orientation molding by a magnetic field molding machine is unnecessary and productivity can be improved and manufacturing costs can be reduced. Here, the content of each component in the isotropic Nd-Fe-B magnet powder used in the present invention is such that Nd is 27 to 40% by weight, Fe is 60 to 70% by weight, and B is 1 to 2% by weight. Small amounts of other elements such as Dy, Tb, Co, Cu, Al, Si, Ga, Nb, V, Pr, Mo, Zr, Ta, Ti, W, Ag, Bi, Zn, Mg to improve magnetic properties May be included.

  A compression bonded magnet made of rare earth magnet powder (particularly Nd—Fe—B magnet powder) contains iron and rare earth that are easily oxidized, and therefore, when used in a corrosive environment with its surface exposed, it is caused by oxidative corrosion. There is a risk of deterioration of magnetic properties and generation of rust. In the case of the compression bonded magnet with the case obtained by the manufacturing method of the present invention, the compression bonded magnet is used in a state of being completely sealed and sealed by the case and the sealing member, so that this corrosion problem can be avoided.

  The average particle diameter (measured value by laser analysis method) of the rare earth magnet powder is preferably 300 μm or less. More preferably, it is 30 micrometers-250 micrometers. Moreover, in order to reduce the space between the particles after compression molding, the particle size distribution preferably has two peaks.

  A thermosetting resin is used as the resin binder for forming the compression bonded magnet. For example, an epoxy resin, a phenol resin, a urea resin, an unsaturated polyester resin, and the like, which are known resin binders for compression bonded magnets, can be used. Among these, it is preferable to use an epoxy resin. Moreover, what has the same curing temperature as the thermosetting resin used for a sealing member is preferable.

  The epoxy resin used as the resin binder may be a resin that can be used as an adhesive epoxy resin, and a resin having a softening temperature of 100 to 120 ° C. is preferable. For example, an epoxy resin that is solid (powder) at room temperature, becomes a paste at 50 to 60 ° C., becomes fluid at 130 to 140 ° C., and starts a curing reaction when further heated is preferred. This curing reaction starts at around 120 ° C., but the temperature at which the curing reaction is completed within a practical curing time, for example, 2 hours, is preferably 170 to 190 ° C. In this temperature range, the curing time is 45 to 80 minutes. By compression-mixing such an epoxy resin (including a latent epoxy curing agent) and a rare earth magnet powder at a temperature not lower than the softening temperature of the epoxy resin and lower than the thermal curing start temperature, as will be described later. The rare earth magnet powder can be uniformly coated with epoxy resin before.

  Examples of the resin component of the epoxy resin used as the resin binder include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, and stilbene type epoxy. Resin, triazine skeleton-containing epoxy resin, fluorene skeleton-containing epoxy resin, alicyclic epoxy resin, novolac-type epoxy resin, acrylic epoxy resin, glycidylamine-type epoxy resin, triphenolphenolmethane-type epoxy resin, alkyl-modified triphenolmethane-type epoxy Examples thereof include resins, biphenyl type epoxy resins, dicyclopentadiene skeleton-containing epoxy resins, naphthalene skeleton-containing epoxy resins, and arylalkylene type epoxy resins.

  It is preferable that the curing agent component of the epoxy resin used as the resin binder is a latent epoxy curing agent. Examples of the latent epoxy curing agent include dicyandiamide, boron trifluoride-amine complex, and organic acid hydrazide. Moreover, hardening accelerators, such as tertiary amine, an imidazole, and an aromatic amine, can be included with a latent epoxy hardening | curing agent. By using the latent epoxy curing agent, the softening temperature can be set to 100 to 120 ° C. and the curing temperature can be set to 170 to 190 ° C. In the compacting process, the rare earth magnet powder is first coated with an epoxy resin. After that, compression molding can be performed.

  For example, in this compacting process, the rare earth magnet powder and the epoxy resin, which is a resin binder, are first mixed thoroughly at room temperature using a blender, and then the mixed mixture is put into a mixer such as a kneader. The mixture is heated and mixed at the softening temperature (100 to 120 ° C.) of the epoxy resin. By this heating and mixing step, the surface of the rare earth magnet powder is uniformly coated with an uncured epoxy resin. The contents heated and mixed using a mixer such as a kneader are in the form of an agglomerated cake. By crushing the agglomerated cake with a Henschel mixer at room temperature and sieving, the surface is coated with a resin binder. A rare earth magnet powder coated with an epoxy resin (uncured) is obtained. A mixture of the rare earth magnet powder and the resin binder in such a state is compression molded to form a green compact. As a result, even when the amount of the resin binder is smaller than usual, segregation of the magnet powder and the resin binder powder having different specific gravities can be reduced as compared with the case where the rare earth magnet powder and the resin binder powder are simply mixed. Further, the compressibility at the time of compacting the compact and the durability of the magnet itself can be improved.

[(B) Compact body insertion process]
As shown in FIG. 2B, the green compact obtained in the compact forming process is inserted into the case. The insertion into the case is preferably press-fitted so that the case and the compression bonded magnet can be brought into close contact with each other. Moreover, you may apply | coat arbitrary adhesive agents between a case and a compression bond magnet.

  The material of the case is not particularly limited, but is preferably a nonmagnetic material because it does not adversely affect the magnetic characteristics. As shown in FIG. 3, when the compression bonded magnet has a substantially cylindrical shape, is magnetized in the radial direction of the cylinder, and the case 3 is disposed so as to cover the outer peripheral surface side and the bottom surface side of the cylinder, Is the shape shown in FIG. Here, by using a non-magnetic material for the case that covers the outer peripheral surface side of the compression bond magnet, the lines of magnetic force from the compression bond magnet are not blocked, and a decrease in magnetic properties can be prevented.

  Examples of the nonmagnetic material forming the case include resin materials, rubber materials, austenitic stainless steel nonmagnetic materials, and the like. Stainless steel non-magnetic materials include sintered parts and machined parts. Sintered parts are advantageous in terms of heat resistance, dimensional accuracy, mass productivity, and cost. Cut parts are heat resistant, dimensional accuracy, and strength. Is advantageous. When using stainless steel cutting products, etc., in order to further improve the adhesion to the sealing member made of thermosetting resin, blasting such as shot sand, machining ( (Surface roughening) and chemicals such as acid may be applied. Further, when a rubber material or a resin material is employed, the degree of freedom in design of the shape is increased, and for example, a fitting structure that is prevented from coming off after the resin is cured can be easily formed on the case side. Cases such as stainless steel non-magnetic materials are generally expensive and inferior in machinability, so the case part has a simple shape and is the minimum size that can hold a compression bond magnet. It is preferable to connect to the tip of the.

[(C) Sealing step- (c1) Coating step]
In the insertion opening of the compact body of the case, a thermosetting resin that becomes a sealing member after curing is applied so as to cover a non-contact portion of the compact with the case while partially contacting the case. Specifically, as shown in FIG. 2 (c), after pressing the green compact 2 'into the case, a thermosetting resin adhesive is applied from the insertion opening side of the case 3 using a dispenser and uncured. A member in a state where the sealing member 4 ′ is applied to the case 3 and the green compact 2 ′ is obtained.

  By using a thermosetting resin adhesive as the material of the sealing member, there is no need for a separate adhesive for fixing the sealing member to the case, and the sealing member is directly fixed by its own adhesive force. be able to. Moreover, it is excellent also in adhesiveness with a compression bond magnet. Furthermore, by adjusting the thermosetting temperature range to the temperature range of the resin binder (thermosetting resin) of the compression bond magnet, the resin binder curing (c2-1) of the compression bond magnet and the curing of the sealing member (c2- 2) can be simultaneously performed by one treatment (c2) of the sealing step. In addition, if necessary, the surface of the resin sealing member may be machined after application formation and curing.

  As shown in FIG. 3, the sealing member 4 has a substantially flat disk shape along the insertion opening 3 a of the case 3 and has a thickness (X) of 0.1 mm or more. It is different from the coating film. In the form shown in the figure, the green compact 2 ′ (or the compression bonded magnet 2) has a substantially cylindrical shape, is magnetized in the radial direction of the cylinder, and covers the outer peripheral surface side and the bottom surface side of the cylinder. 3 is disposed, and the sealing member 4 is disposed on the upper surface side of the cylinder. With this structure, the lines of magnetic force have the shape shown in FIG. 4, and the detection sensor 5 is disposed above the compression bonded magnet. Due to the shape of the lines of magnetic force, the detection sensor 5 is not provided in close proximity to the magnet surface, but is provided with a gap. Although the sealing member 4 is thicker than a normal coating film, since it can be disposed within this gap range, it does not adversely affect sensor sensitivity or the like. In order to achieve stable adhesion and high corrosion resistance, the thickness (X) of the sealing member 4 is preferably 0.3 mm to 1.0 mm.

  The thickness (Y) of the collar portion of the sealing member 4 is preferably about the same as the thickness (X) of the main body, for example, about ± 20%. Moreover, it is preferable that the thickness (Z) of the collar part of the sealing member 4 is set to be twice the thickness (X) of the main body part to the height of the insertion opening 3a. More preferably, it is 2 to 4 times the thickness (X) of the main body.

  Further, as shown in FIG. 3, it is preferable to have a structure in which the sealing member 4 is interposed between a part of the cylindrical upper surface side of the outer peripheral surface of the green compact 2 ′ (or the compression bonded magnet 2) and the case 3. . Thereby, the joining area of the case 3 and the sealing member 4 becomes large at the edge of the insertion opening 3a, and the adhesive strength and the barrier property of the corrosive fluid are excellent. In the structure shown in FIG. 3B, the cylindrical height of the green compact 2 ′ (or the compression bonded magnet 2) is made smaller than the height of the insertion opening 3a (this difference becomes the thickness (X)), Further, a stepped portion 2a toward the inner diameter side is provided in advance on a part of the cylindrical upper surface side of the outer peripheral surface of the green compact 2 'during compression molding (the axial length of the stepped portion 2a becomes the thickness (Z), and the diameter The direction length is the thickness (Y)). The stepped portion 2a is not in contact with the case 3. The step 2 is formed by inserting or press-fitting the green compact 2 ′ (or the compression bonded magnet 2) of this shape into the case 3, applying a thermosetting resin adhesive to the edge of the insertion opening 3 a, and performing a thermosetting treatment. 2a is also filled with a resin adhesive, and a substantially flat disk-shaped sealing member 4 with a flange having the structure of the thickness (X) (Y) (Z) is obtained. The step 2a of the green compact 2 '(or the compression bonded magnet 2) becomes a resin reservoir.

  Examples of the thermosetting resin adhesive used for the sealing member include an epoxy resin adhesive, a phenol resin adhesive, and an acrylic resin adhesive that are excellent in heat resistance and corrosion resistance. As the epoxy resin, a one-component or two-component epoxy resin adhesive having the same resin components as those listed for the resin binder and capable of solvent dilution can be used. As the curing agent in the epoxy resin adhesive, in addition to the latent epoxy curing agent, an amine curing agent, a polyamide curing agent, an acid anhydride curing agent, and the like can be used as appropriate, and a curing temperature range and a curing time can be used. Is preferably the same as the resin binder. As the phenol resin adhesive, for example, a novolak type phenol resin or a resol type phenol resin as a resin component, hexamethylenetetramine or the like as a curing agent, and the like dissolved in a solvent such as methyl ethyl ketone can be used.

  Since the thermosetting resin adhesive is used not for the purpose of sealing the green compact but as a thick film sealing member, the viscosity thereof is preferably higher than that for sealing. Specifically, the viscosity (mPa · s) at 25 ° C. is preferably 100 to 20000 mPa · s, more preferably 500 to 10000 mPa · s. By setting it as this range, it is excellent in adhesiveness with a case and a compact. Further, it is possible to easily form a sealing member having a desired film thickness on the surface of the green compact by suppressing the amount of adhesive penetrating into the voids of the green compact. As a method for applying the thermosetting resin adhesive to the surface of the green compact, known methods such as spray coating and dispenser coating can be employed. It is preferable to employ a dispenser coating because an adhesive having a high viscosity can be used, a thick film can be easily formed, and waste of paint can be eliminated.

[(C) Sealing step- (c2) Thermosetting step]
The member applied with the uncured thermosetting resin adhesive is subjected to a heat treatment to cure the adhesive (c2-2). As shown in FIG.2 (d), heat processing puts this member in the dryer 10, and is more than the thermosetting start temperature (for example, 170-190 degreeC) of the resin binder and thermosetting resin adhesive in a green compact. 200 ° C. or lower) at normal pressure and for a time during which curing proceeds sufficiently. The curing temperature range and curing time of the resin binder and the thermosetting resin adhesive in the green compact are matched by selecting the material. The temperature above the thermosetting start temperature of the resin binder and the thermosetting resin adhesive is 200 ° C. or less, for example, 170 to 190 ° C. is there.

  As a result, the resin binder in the compact is cured and the rare earth magnet powder is bound by the binder to form the compression bond magnet 2 (c2-1). At the same time, the sealing member 4 is the case 3 and the compression bond magnet 2. The compression-bonded magnet with the case in which the compression-bonded magnet 2, the case 3, and the sealing member 4 are integrated is obtained. Finally, the compression bonded magnet 2 is magnetized in the radial direction to obtain a finished product.

  As described above, in the embodiment described based on FIG. 1 and FIG. 2, the curing process of the compression bonded magnet and the curing process of the sealing member can be performed in the same process, and the manufacturing process and the processing cost can be greatly reduced. It becomes possible to manufacture a compression bonded magnet with a case at low cost and productivity. In addition, the heat treatment in the sealing process can be performed at a temperature of 200 ° C. or less and under normal pressure (in air), and no heat treatment under vacuum or high temperature is required, so that production with higher productivity and lower cost can be achieved. It becomes possible.

  As another aspect of the compression bond magnet in the compact insertion process, the resin binder in the green compact can be cured before the insertion into the case to complete the compression bond magnet. In this case, the resin binder may be cured by adjusting the mold temperature for compression molding to be equal to or higher than the thermosetting temperature of the resin binder. After heat curing by heat treatment, machining such as cutting and barreling can be performed as necessary, but the machining cost can be reduced because there is less shrinkage due to heat treatment compared to sintered magnets. In addition, since the magnet of the present invention is not subjected to high-temperature heat treatment (for example, 500 ° C. or higher) such as sintering, it can maintain high magnetic characteristics without deterioration of magnetic characteristics during the manufacturing process, and reduce manufacturing costs. it can.

  As another aspect of the sealing member in the sealing step, the case is prepared in advance as a metal or resin molded body separate from the case, and a green compact (or a compression bonded magnet) is inserted into the case. It may be fixed to. The means for fixing the sealing member to the case in the sealing step depends on the material and structure of the sealing member, and adhesive fixing, press-fit fixing, shape fitting fixing by a hook structure, and the like can be employed. Moreover, when providing the sealing member which consists of a resin molding, it is preferable to provide the case side with the structure used as a retaining after resin hardening.

  Moreover, it is good also as an aspect which arrange | positions the case in which the green compact (or compression bond magnet) was inserted in a metal mold | die, and provides a sealing member in this by injection molding (insert molding) of a resin composition. As the resin, a thermoplastic resin that can be injection-molded can be used. Examples of such thermoplastic resins include polyolefin resins such as polyethylene resins and polypropylene resins, polyphenylene sulfide (PPS) resins, liquid crystal polymers, polyether ether ketone (PEEK) resins, polyimide resins, polyether imide resins, polyacetal resins, poly Examples include ether sulfone resins, polycarbonate resins, polyethylene terephthalate resins, polybutylene terephthalate resins, polyphenylene oxide resins, polyphthalamide resins, polyamide resins, or mixtures thereof. Among these, PPS resin or PEEK resin excellent in corrosion resistance and heat resistance is preferable. Moreover, this resin composition may contain an arbitrary compounding agent as long as the function as a sealing member is not impaired. For the injection molding method, injection molding conditions, and injection mold, known methods and conditions can be adopted according to the type of resin.

  The method of manufacturing a compression bonded magnet with a case according to the present invention can manufacture a compression bonded magnet with a case having high magnetic properties, high corrosion resistance, and high durability strength at high productivity and low cost. It can utilize for manufacture of the sensor magnet of the sensor for angle detection used in various field | areas. In particular, corrosion resistance is required in contact with fluids such as water, oil, and exhaust gas, such as the rotation angle detection sensor of the coolant switching valve, the oil pump opening / closing angle detection sensor, and the fuel pump opening / closing angle detection sensor. The present invention can be suitably used for manufacturing a sensor magnet for a sensor used in a corrosive environment.

DESCRIPTION OF SYMBOLS 1 Compression bond magnet with case 2 Compression bond magnet 2 'Compact 3 Case 4 Sealing member 4' Uncured sealing member 5 Detection sensor 6 Dice 7 Upper punch 8 Lower punch 9 Dispenser 10 Dryer

Claims (6)

A compression bond magnet including a rare earth magnet powder and a thermosetting resin resin binder, a case into which the compression bond magnet is inserted, and a sealing member, the compression bond magnet including the sealing member and the case A method for producing a compression bonded magnet with a case sealed with
A compact forming step of forming a compact by compression molding a mixture containing the rare earth magnet powder and the resin binder;
A green compact after the resin binder is cured or a green compact insertion step of inserting the green compact before the resin binder is cured;
A method for producing a compression-bonded magnet with a case, comprising: a sealing step of fixing a sealing member to an insertion opening of the compact in the case. The green compact insertion step is a step of inserting the compact before the resin binder is cured into the case,
In the sealing step, in the insertion opening of the powder body of the case, the thermosetting resin that becomes the sealing member after curing partially contacts the case without contacting the case with the powder body. Apply to cover the part,
Forming the thermosetting resin and the resin binder while fixing the sealing member to the case by curing the thermosetting resin by heat treatment at a temperature equal to or higher than the thermosetting start temperature of the resin binder, and in the green compact The method for producing a compressed bond magnet with a case according to claim 1, wherein the compressed bond magnet is formed by curing a resin binder. The case is made of a non-magnetic material,
The green compact and the compression bonded magnet have a substantially cylindrical shape, are magnetized in the radial direction of the cylinder, the case is disposed to cover the outer peripheral surface side and the bottom surface side of the cylinder, and the upper surface side of the cylinder The method for manufacturing a compression-bonded magnet with a case according to claim 1, wherein the sealing member is disposed in the casing. The case is made of a non-magnetic material,
The green compact and the compression bonded magnet have a substantially cylindrical shape, are magnetized in the radial direction of the cylinder, the case is disposed to cover the outer peripheral surface side and the bottom surface side of the cylinder, and the upper surface side of the cylinder The sealing member is disposed on
The green compact has a stepped portion that is not in contact with the case at least at the end of the outer peripheral surface of the cylindrical upper surface, and the stepped portion is filled with the thermosetting resin in the sealing step. The method for manufacturing a compression-bonded magnet with a case according to claim 2, wherein a part of the sealing member is formed in the portion.   The method for producing a compression-bonded magnet with a case according to claim 2 or 4, wherein the heat treatment in the sealing step is performed at a temperature of 200 ° C or lower and under normal pressure.   The rare earth magnet powder is an isotropic Nd-Fe-B magnet powder, and the magnet powder is contained in a volume ratio of 85 to 90% with respect to the entire compression bonded magnet. 6. A method for producing a compression bonded magnet with a case according to claim 5.

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