Molded article and method for producing molded article

Abstract

This molded article, in which a bond magnet is bonded to a surface of a shaft, has a plurality of recesses independent of each other on a bonding surface to which the bond magnet of the shaft is bonded. This method for producing a molded article, in which a bond magnet is bonded to a surface of a shaft, comprises: a recess formation step for forming a plurality of recesses independent of each other on a bonding surface to which the bond magnet of the shaft is bonded; and a bonding step for bonding the bond magnet to the bonding surface on which the plurality of recesses have been formed in the recess formation step.

Description

Molded product and manufacturing method of molded product

[0001] The present disclosure relates to a molded article in which a bonded magnet is joined to a shaft, and a method for manufacturing the molded article.

[0002] Patent Document 1 describes a molded product (shaft-integrated bonded magnet) in which a cylindrical bonded magnet is integrally provided on the circumferential surface of a cylindrical shaft. In this molded product, a U-groove is formed on the outer circumferential surface at the axial center of the shaft to improve the bonding strength between the shaft and the bonded magnet.

[0003] Japanese Patent Application Laid-Open No. 2018-037620

[0004] However, in the molded product described in Patent Document 1, grooves are formed on the outer peripheral surface of the shaft, which poses the problem that the strength of the shaft is likely to decrease if the grooves are made deeper. Also, while the bond strength between the shaft and bonded magnet is improved in the direction intersecting the extension direction of the grooves, the bond strength between the shaft and bonded magnet may not necessarily be sufficient in the extension direction of the grooves.

[0005] Therefore, an object of the present disclosure is to provide a molded product and a method for manufacturing the molded product that can increase the bonding strength between a shaft and a bonded magnet.

[0006] [1] The molded product according to the present disclosure is a molded product in which a bonded magnet is bonded to the surface of a shaft, and the surface of the shaft to which the bonded magnet is bonded has a plurality of recesses that are independent of each other.

[0007] In this molded product, the joining surface of the shaft has multiple independent recesses, so the bonded magnets are embedded in multiple recesses and each recess is surrounded by the bonded magnets, which increases the joining strength between the shaft and the bonded magnet.

[0008] [2] In the molded article described in [1], the plurality of recesses may be arranged at equal intervals. In this molded article, the plurality of recesses are arranged at equal intervals, which makes it easy to form the plurality of recesses. In addition, it is possible to further suppress variations in the bonding strength between the shaft and the bonded magnet depending on the position.

[0009] [3] In the molded product according to [1] or [2], the surface of the shaft has a non-bonded surface to which the bonded magnet is not bonded, and the non-bonded surface may not have multiple dents. In this molded product, since the non-bonded surface of the shaft does not have multiple dents, it is possible to prevent other components from coming into contact with the multiple dents and being damaged. In addition, it is possible to prevent the appearance of the molded product from being deteriorated due to the multiple dents being exposed, and it is also possible to prevent contamination of the molded product due to dust getting into the multiple dents.

[0010] [4] In the molded article according to any one of [1] to [3], the outer shape of the plurality of depressions may be circular, rectangular, diamond-shaped, star-shaped polygonal, or four-lobed. In this molded article, the outer shape of the plurality of depressions is circular, rectangular, diamond-shaped, star-shaped polygonal, or four-lobed, which makes it possible to easily form the plurality of depressions.

[0011] [5] In the molded article according to any one of [1] to [4], the maximum depth of the plurality of recesses may be 0.1 mm or more and 4.0 mm or less. In this molded article, since the maximum depth of the plurality of recesses is 0.1 mm or more and 4.0 mm or less, the plurality of recesses can be easily formed while ensuring the bonding strength between the shaft and the bonded magnet.

[0012] [6] In the molded article according to any one of [1] to [5], the maximum length of the plurality of recesses may be 0.01 mm or more and 30 mm or less. In this molded article, since the maximum length of the plurality of recesses is 0.1 mm or more and 30 mm or less, it is possible to prevent a decrease in the strength of the shaft while ensuring the bonding strength between the shaft and the bonded magnet.

[0013] [7] In the molded article according to any one of [1] to [6], the minimum distance between the plurality of recesses may be 0.1 mm or more and 30 mm or less. In this molded article, the minimum distance between the plurality of recesses is 0.1 mm or more and 30 mm or less, so that the plurality of recesses can be easily formed while ensuring the bonding strength between the shaft and the bonded magnet.

[0014] [8] In the molded product according to any one of [1] to [7], the bonded magnet has a magnet powder and a resin portion, and the resin portion may include a cured thermosetting resin, and the thermosetting resin may include an epoxy resin and a phenolic resin. In this molded product, the resin portion of the bonded magnet includes a cured thermosetting resin, and the thermosetting resin includes an epoxy resin and a phenolic resin, so that the affinity between the resin portion and the shaft is increased, and the adhesion between the resin portion and the shaft is improved. This further increases the bond strength between the shaft and the bonded magnet.

[0015] [9] The manufacturing method of a molded product according to the present disclosure is a manufacturing method of a molded product in which a bonded magnet is bonded to the surface of a shaft, and includes a recess forming step of forming a plurality of recesses independent of each other on the joining surface of the shaft to which the bonded magnet is joined, and a joining step of joining the bonded magnet to the joining surface of the shaft on which the plurality of recesses has been formed.

[0016] This method of manufacturing a molded product involves forming multiple independent recesses on the joining surface of the shaft, and then joining a bonded magnet to the joining surface of the shaft on which the multiple recesses are formed, making it easy to manufacture the above-mentioned molded product.

[0017]

[10] In the manufacturing method of the molded product described in [9], the joining step may include a molding step in which a bond magnet compound is compression molded while in contact with the joining surfaces. In this manufacturing method of the molded product, by compression molding the bond magnet compound while in contact with the joining surfaces, the bond magnet can be easily joined to the joining surfaces.

[0018]

[11] In the manufacturing method of a molded product described in

[10] , the joining step may include a coating step of forming a resin film containing the same resin as that contained in the bond magnet on the joining surface, and a molding step of compression molding the bond magnet compound with the bond magnet compound in contact with the resin film. In this manufacturing method of a molded product, by forming a resin film containing the same resin as that contained in the bond magnet on the joining surface and compression molding the bond magnet compound with the bond magnet compound in contact with the resin film, the bond magnet can be joined to the joining surface with high joining strength.

[0019]

[12] In the method for manufacturing a molded product described in

[11] , the coating step may involve applying a resin solution containing the same resin as that contained in the bonded magnet to the joining surface, and then drying the resin solution. In this method for manufacturing a molded product, applying a resin solution containing the same resin as that contained in the bonded magnet to the joining surface allows the resin solution to fill multiple recesses. Then, by drying the resin solution, a resin film can be easily formed on the joining surface with high joining strength.

[0020] The bond strength between the shaft and the bonded magnet can be increased.

[0021] FIG. 1 is a perspective view showing a molded product according to an embodiment. FIG. 2 is a cross-sectional view showing a molded product according to an embodiment. FIG. 3 is a front view showing a shaft of the molded product according to an embodiment. FIG. 4 is a cross-sectional view showing an enlarged portion of the shaft of the molded product according to an embodiment. FIGS. 5(a) and 5(b) are front views showing examples of the outer shape of a depression. FIGS. 6(a) and 6(b) are front views showing examples of the outer shape of a depression. FIGS. 7(a) and 7(b) are front views showing examples of the outer shape of a depression. FIG. 8 is a cross-sectional view showing an enlarged portion of a molded product according to an embodiment. FIG. 9 is a front view for explaining a method for manufacturing a molded product according to an embodiment. FIG. 10 is a cross-sectional view for explaining a method for manufacturing a molded product according to an embodiment. FIG. 11 is a cross-sectional view for explaining a method for manufacturing a molded product according to a modified example.

[0022] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and duplicate explanations will be omitted. Also, in the drawings, dimensional proportions and the like have been appropriately changed to make the explanation easier to understand.

[0023] Fig. 1 is a perspective view showing a molded product according to an embodiment. Fig. 2 is a cross-sectional view showing a molded product according to an embodiment. As shown in Figs. 1 and 2, the molded product 1 according to this embodiment includes a shaft 2 and a bonded magnet 3 bonded to the surface of the shaft 2. The molded product 1 is also called a shaft-integrated molded product, etc. Examples of such molded products 1 include a shaft-integrated rotor for a motor, a sensor component, etc.

[0024] FIG. 3 is a front view showing a shaft of a molded product according to an embodiment. As shown in FIGS. 1 to 3 , the shaft 2 is a cylindrical metal member. Metallic materials for the shaft 2 include, for example, alloy steel, carbon steel, stainless steel, and bearing steel. Major products include the SCR / SCM / SNC / SNCM / SACM series, SC series, SUS series, and SUJ series. The shaft 2 has a bonded surface 2a to which the bonded magnet 3 is bonded and a non-bonded surface 2b to which the bonded magnet 3 is not bonded. The bonded surface 2a and the non-bonded surface 2b are surfaces of the shaft 2 that form the circumferential surface of the shaft 2. The bonded surface 2a is located, for example, in the center in the axial direction AD of the shaft 2. The axial direction AD of the shaft 2 is a direction along the central axis A. The non-bonded surfaces 2b are located, for example, on both sides of the non-bonded surface 2b in the axial direction AD of the shaft 2.

[0025] Figure 4 is an enlarged cross-sectional view of a portion of a shaft of a molded product according to an embodiment. As shown in Figures 1 to 4, the joining surface 2a has a plurality of recesses 4 that are independent of one another. The recesses 4 are not connected to one another and are spaced apart from one another. Each of the plurality of recesses 4 (hereinafter simply referred to as a "recess 4") is recessed from the circumferential surface 21 and is surrounded by the circumferential surface 21. The recesses 4 are also called dimples, etc. The recesses 4, together with the circumferential surface 21, form the joining surface 2a of the shaft 2.

[0026] The multiple recesses 4 may be formed over the entire joining surface 2a in the axial direction AD, or may be formed only on a part of the joining surface 2a in the axial direction AD, but in this embodiment, as an example, they are formed over the entire joining surface 2a in the axial direction AD.

[0027] The non-bonding surface 2b may or may not have multiple recesses 4, but in the present embodiment, as an example, it does not have multiple recesses 4. When the non-bonding surface 2b has multiple recesses 4, the multiple recesses 4 may be formed over the entire non-bonding surface 2b in the axial direction AD, or may be formed only in a part of the non-bonding surface 2b in the axial direction AD.

[0028] The multiple depressions 4 may or may not be arranged at equal intervals, but in this embodiment, as an example, the multiple depressions 4 are arranged at equal intervals so that when multiple triangles are laid out without any gaps, a depression 4 is located at the vertex of each triangle.

[0029] The outer shape of the depression 4 is, for example, circular, rectangular, diamond-shaped, star-shaped polygonal, or four-leaf shape. Figures 5(a), 5(b), 6(a), 6(b), 7(a), and 7(b) are front views showing examples of the outer shapes of depressions. The depression 4 shown in Figure 5(a) has a circular outer shape. The depression 4 shown in Figure 5(b) has a square (rectangular) outer shape. The depression 4 shown in Figure 6(a) has a rectangular (rectangular) outer shape. The depression 4 shown in Figure 6(b) has a diamond-shaped outer shape. The depression 4 shown in Figure 7(a) has a star-shaped polygonal outer shape. The depression 4 shown in Figure 7(b) has a four-leaf shape.

[0030] 4, the maximum depth D of the recess 4 is, for example, 0.1 mm to 4 mm, preferably 0.2 mm to 3 mm, and more preferably 0.3 mm to 2 mm. The maximum depth D of the recess 4 is the maximum depth of the recess 4 with respect to an imaginary circumferential surface obtained by extending the circumferential surface 21 onto the recess 4.

[0031] The maximum length L of the recess 4 is 0.01 mm to 30 mm, preferably 1 mm to 20 mm, and more preferably 2 mm to 10 mm. The maximum length L of the recess 4 is the maximum linear distance between both ends of the recess 4 connected to the peripheral surface 21 in a cross section perpendicular to the central axis A.

[0032] As shown in FIG. 5( a), in the case of a depression 4 having a circular outer shape, the diameter of the depression 4 is the maximum length L of the depression 4. As shown in FIGS. 5( b) and 6( a), in the case of a depression 4 having a rectangular outer shape, the length of the diagonal of the depression 4 is the maximum length L of the depression 4. As shown in FIG. 6( b), in the case of a depression 4 having a diamond outer shape, the length of the long diagonal of the depression 4 is the maximum length L of the depression 4. As shown in FIG. 7( a), in the case of a depression 4 having a star-shaped outer shape, the length between the furthest vertices of the depression 4 is the maximum length L of the depression 4. As shown in FIG. 7( b), in the case of a depression 4 having a four-lobe outer shape, the length between the furthest vertices is the maximum length L of the depression 4.

[0033] 4, the minimum spacing S between the plurality of recesses 4 is 0.1 mm or more and 30 mm or less, preferably 1 mm or more and 20 mm or less, and more preferably 2 mm or more and 10 mm or less. The minimum spacing S between the recesses 4 is the spacing between the closest recesses 4.

[0034] Figure 8 is an enlarged cross-sectional view of a portion of the molded product according to the embodiment. As shown in Figures 1 to 4 and 8, bond magnet 3 is bonded to joining surface 2a of shaft 2. In other words, bond magnet 3 is bonded to circumferential surface 21 that forms joining surface 2a of shaft 2 and to recess 4. Note that "bond magnet 3 being bonded to recess 4" means that bond magnet 3 enters recess 4 and is bonded to the surface of recess 4. Bond magnet 3 has magnetic powder 3a and a resin portion 3b. Magnetic powder 3a is dispersed in resin portion 3b.

[0035] The magnet powder 3a may be any magnetic powder, and rare earth magnetic powder is preferable.

[0036] Examples of rare earth magnetic powders include samarium-cobalt magnetic powder (SmCo), neodymium-iron-boron magnetic powder (NdFeB), and samarium-iron-nitride compound magnetic powder (SmFeN). Rare earth magnetic powders are manufactured, for example, by a rapid solidification method. In the rapid solidification method, a molten magnet alloy is released onto the surface of a rotating water-cooled roll, whereby the molten magnet alloy is rapidly cooled and solidified to produce a quenched alloy. The quenched alloy is then pulverized to produce the rare earth magnetic powder. Rare earth magnetic powder manufactured by the HDDR (Hydrogenation Disproportion Desorption Recombination) method may also be used.

[0037] The rare earth magnetic powder is preferably a powder containing an Nd--Fe--B permanent magnet (NdFeB powder).

[0038] The rare earth magnetic powder may also be a powder containing an Sm--Fe--N permanent magnet (SmFeN powder).

[0039] The magnet powder 3a is, for example, a powder containing an Sm—Fe—N permanent magnet (SmFeN powder). The average particle size of the SmFeN powder may be preferably 0.5 μm or more and 100 μm or less, more preferably 1 μm or more and 10 μm or less, and even more preferably 2 μm or more and 3 μm or less. The average particle size of the SmFeN powder can be measured using a laser diffraction particle size distribution analyzer. For example, the SmFeN powder may be a non-pulverized powder (spherical magnet powder) obtained by the build-up method of Nichia Corporation. The surface of each magnet particle constituting the SmFeN powder may be coated with an inorganic film by surface treatment. For example, the inorganic film may contain a phosphate or a silica-based compound.

[0040] The resin portion 3b includes a cured product of a thermosetting resin. The thermosetting resin includes an epoxy resin and a phenol resin. The thermosetting resin preferably includes a naphthalene-type epoxy resin and a phenol resin.

[0041] The naphthalene-type epoxy resin is preferably a tetrafunctional naphthalene-based epoxy resin, and also preferably a trifunctional naphthalene-based epoxy resin or a β-naphthol-type epoxy resin. Commercially available naphthalene-type epoxy resins include, for example, HP-4700 manufactured by DIC Corporation. ＴＭ , EXA-5740 ＴＭ , or EXA-7311-G4 ＴＭ These may be used alone or in combination of two or more.

[0042] Examples of phenolic resins include compounds having two phenolic hydroxyl groups per molecule, such as aralkyl phenolic resins, dicyclopentadiene phenolic resins, salicylaldehyde phenolic resins, novolac phenolic resins, copolymerized phenolic resins of benzaldehyde phenols and aralkyl phenols, paraxylylene and / or metaxylylene-modified phenolic resins, melamine-modified phenolic resins, terpene-modified phenolic resins, dicyclopentadiene naphthol resins, cyclopentadiene-modified phenolic resins, polycyclic aromatic ring-modified phenolic resins, biphenyl phenolic resins, triphenylmethane phenolic resins, and phenolic resins obtained by copolymerizing two or more of these. These may be used alone or in combination. Examples include resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenols. Commercially available phenolic resins include, for example, Tamanol 758 and 73.0 manufactured by Arakawa Chemical Industries, Ltd., and HP-850N manufactured by Resonac Corporation. ＴＭ These may be used alone or in combination of two or more.

[0043] Next, a method for manufacturing a molded article according to the embodiment will be described. The method for manufacturing a molded article according to the embodiment is a method for manufacturing the molded article 1 described above. Fig. 9 is a front view for explaining the method for manufacturing a molded article according to the embodiment. Fig. 10 is a cross-sectional view for explaining the method for manufacturing a molded article according to the embodiment.

[0044] First, a cylindrical shaft 102 is prepared as shown in Fig. 9. The shaft 102 is similar to the shaft 2 except that the plurality of recesses 4 are not formed.

[0045] 9 and 3, a recess forming step is performed to form a plurality of recesses 4 that are independent of one another on the circumferential surface 21 of the shaft 102 located at the joining surface 2a. The plurality of recesses 4 are formed, for example, by pressing a mold corresponding to the plurality of recesses 4 against the circumferential surface 21 of the shaft 102. This results in a shaft 2 having a plurality of recesses 4 formed on the circumferential surface 21.

[0046] Next, a joining process is carried out in which a bond magnet 3 is joined to the joining surface 2a of the shaft 2 on which multiple recesses 4 have been formed in the recess forming process. As shown in Figure 10, in the joining process, a molding process is carried out in which bond magnet compound 103 is compression molded while in contact with joining surface 2a. Bond magnet compound 103 is a compound that becomes bond magnet 3 when compacted. Bond magnet compound 103 includes, for example, the above-mentioned magnet powder 3a and a resin composition.

[0047] The resin composition contains at least the thermosetting resin described above. The resin composition may further contain at least one component selected from the group consisting of a curing agent, a curing accelerator, a coupling agent, a flame retardant, and a flow aid. The bonded magnet compound 103 itself may contain an organic solvent.

[0048] The bonded magnet compound 103 may contain wax. The wax may be at least one composition selected from the group consisting of synthetic wax, saturated fatty acid, saturated fatty acid salt, metal soap, and saturated fatty acid ester. For example, the wax may be at least one wax selected from the group consisting of polyethylene wax, amide wax, and montan wax.

[0049] In the molding process, for example, a manufacturing device 5 is used that includes cylindrical upper punch 51 and lower punch 52 facing each other, and a die 53 formed with holes 53a into which the upper punch 51 and the lower punch 52 can be inserted. In this manufacturing device 5, the inner diameters of the upper punch 51 and the lower punch 52 and the outer diameter of the shaft 2 are approximately the same, and the outer diameters of the upper punch 51 and the lower punch 52 and the inner diameter of the hole 53a of the die 53 are approximately the same.

[0050] In the forming process using the manufacturing apparatus 5, first, the non-bonding surface 2b of the shaft 2 is inserted into the upper punch 51 or the lower punch 52. Next, the space surrounded by the die 53 and the lower punch 52, or the space surrounded by the die 53, the lower punch 52, and the shaft 2, is filled with the bond magnet compound 103. Next, the upper punch 51 is forced into the hole 53a to press the bond magnet compound 103. The bond magnet compound 103 is then compression molded while in contact with the bonding surface 2a, and the bond magnet 3 is bonded to the bonding surface 2a. This results in the molded product 1 in which the bond magnet 3 is bonded to the bonding surface 2a of the shaft 2. The molded product 1 is then removed from the die 53, and the molded product 1 is obtained.

[0051] As explained above, in molded product 1 according to this embodiment, bonding surface 2a of shaft 2 has a plurality of recesses 4 that are independent of one another, so that bond magnet 3 enters a plurality of recesses 4, and the bond magnet 3 that enters each recess 4 is surrounded by each recess 4. This increases the bonding strength between shaft 2 and bond magnet 3.

[0052] Furthermore, in this molded product 1, multiple recesses 4 are arranged at equal intervals, making it easy to form multiple recesses 4. In addition, it is possible to further reduce variations in the bonding strength between shaft 2 and bonded magnet 3 depending on the position.

[0053] Furthermore, in this molded article 1, the non-joint surface 2b of the shaft 2 does not have the multiple dents 4, which prevents other members from coming into contact with and being damaged by the multiple dents 4. Furthermore, it is possible to prevent the appearance of the molded article 1 from being deteriorated due to the multiple dents 4 being exposed, and it is also possible to prevent contamination of the molded article 1 due to dust getting into the multiple dents 4.

[0054] Furthermore, in this molded product 1, the outer shape of the depressions 4 is circular, rectangular, diamond-shaped, star-shaped, or tetralobed, so that a plurality of depressions 4 can be easily formed.

[0055] Furthermore, in this molded product 1, the maximum depth D of the multiple recesses 4 is 0.1 mm or more and 4 mm or less, preferably 0.2 mm or more and 3 mm or less, and more preferably 0.3 mm or more and 2 mm or less, so that the multiple recesses 4 can be easily formed while ensuring the bonding strength between the shaft 2 and the bonded magnet 3.

[0056] Furthermore, in this molded product 1, the maximum length L of the multiple recesses 4 is 0.01 mm or more and 30 mm or less, preferably 1 mm or more and 20 mm or less, and more preferably 2 mm or more and 10 mm or less, so that the bonding strength between the shaft 2 and the bonded magnet 3 can be ensured while preventing a decrease in the strength of the shaft 2.

[0057] Furthermore, in this molded product 1, the minimum separation distance S between the multiple recesses 4 is 0.1 mm or more and 30 mm or less, preferably 1 mm or more and 20 mm or less, and more preferably 2 mm or more and 10 mm or less, so that the multiple recesses 4 can be easily formed while ensuring the bonding strength between the shaft 2 and the bonded magnet 3.

[0058] Furthermore, in this molded product 1, resin portion 3b of bonded magnet 3 contains a cured product of thermosetting resin, and the thermosetting resin contains epoxy resin (preferably naphthalene-type epoxy resin) and phenolic resin, which increases the affinity between resin portion 3b and shaft 2 and improves the adhesion between resin portion 3b and shaft 2. This further increases the bond strength between shaft 2 and bonded magnet 3.

[0059] In the manufacturing method of the molded product according to this embodiment, a plurality of mutually independent recesses 4 are formed on the joining surface 2a of the shaft 2, and a bonded magnet 3 is joined to the joining surface 2a of the shaft 2 on which the plurality of recesses 4 are formed, so that the above-mentioned molded product 1 can be easily manufactured.

[0060] Furthermore, in this manufacturing method of the molded product, the bond magnet compound 103 is compression molded while being in contact with the joining surface 2a, so that the bond magnet 3 can be easily joined to the joining surface 2a.

[0061] The present disclosure is not limited to the above-described embodiments, and modifications can be made as appropriate without departing from the spirit of the present disclosure.

[0062] For example, in the method for producing a molded article, a molded article may be obtained by carrying out the coating step and molding step described below.

[0063] Figure 11 is a cross-sectional view illustrating a manufacturing method for a molded product of a modified example. As shown in Figure 11, first, a coating step is performed to form a resin film 103b containing the same resin as that contained in bond magnet 3 on joining surface 2a. The resin contained in bond magnet 3 is the resin contained in resin portion 3b, and is, for example, a thermosetting resin containing the above-mentioned naphthalene-type epoxy resin and phenol resin. In the coating step, for example, a resin solution containing the same resin as that contained in bond magnet 3 is applied to joining surface 2a, and the resin solution is dried to form resin film 103b on joining surface 2a.

[0064] Next, a molding process is performed in which bond magnet compound 103 is compression molded while in contact with resin film 103b. This molding process is basically the same as the molding process of the above embodiment, except that shaft 2 having resin film 103b formed on joining surface 2a is used. This results in a molded product 1 similar to that of the above embodiment.

[0065] As explained above, in the manufacturing method of the molded product according to this embodiment, a resin film 103b containing the same resin as that contained in the bond magnet 3 is formed on the joining surface 2a, and the bond magnet compound 103 is compression molded while being in contact with the resin film 103b, thereby making it possible to join the bond magnet 3 to the joining surface 2a with high joining strength.

[0066] Furthermore, in this manufacturing method for a molded product, by applying a resin solution containing the same resin as that contained in bond magnet 3 to joining surface 2a, the resin solution can be allowed to fill multiple depressions 4. Then, by drying this resin solution, resin film 103b can be easily formed on joining surface 2a with high joining strength.

[0067] The present disclosure can be used as a molded article in which a bonded magnet is bonded to a shaft, and a method for manufacturing the molded article.

[0068] 1...molded product, 2...shaft, 2a...bonding surface, 2b...non-bonding surface, 3...bonded magnet, 3a...magnetic powder, 3b...resin portion, 4...depression, 5...manufacturing apparatus, 21...periphery, 51...upper punch, 52...lower punch, 53...die, 53a...hole, 102...shaft, 103...bonded magnet compound, 103b...resin film, A...central axis, AD...axial direction, D...maximum depth, L...maximum length, S...minimum separation distance.

Claims

1. A molded product in which a bonded magnet is bonded to the surface of a shaft, wherein the surface of the shaft to which the bonded magnet is bonded has a plurality of recesses that are independent of each other.

2. The molded product according to claim 1, wherein the plurality of recesses are arranged at equal intervals.

3. The molded product according to claim 1 or 2, wherein the surface of the shaft has a non-bonded surface to which the bonded magnet is not bonded, and the non-bonded surface does not have the plurality of recesses.

4. The molded product according to claim 1 or 2, wherein the outer shape of the plurality of recesses is circular, rectangular, diamond-shaped, star-shaped, or tetralobed.

5. The molded product according to any one of claims 1 to 4, wherein the maximum depth of the plurality of depressions is 0.1 mm or more and 4 mm or less.

6. The molded product according to any one of claims 1 to 5, wherein the maximum length of the plurality of recesses is 0.01 mm or more and 30 mm or less.

7. The molded product according to any one of claims 1 to 6, wherein the minimum distance between the plurality of recesses is 0.1 mm or more and 30 mm or less.

8. The molded product according to any one of claims 1 to 7, wherein the bonded magnet has a magnetic powder and a resin portion, the resin portion includes a cured product of a thermosetting resin, and the thermosetting resin includes an epoxy resin and a phenolic resin.

9. A method for manufacturing a molded product in which a bonded magnet is bonded to the surface of a shaft, comprising: a recess forming step of forming a plurality of recesses that are independent of each other on the joining surface of the shaft to which the bonded magnet will be joined; and a joining step of joining the bonded magnet to the joining surface of the shaft on which the plurality of recesses have been formed.

10. A method for manufacturing a molded product as set forth in claim 9, wherein the joining step includes a molding step of compression molding a bond magnet compound while the bond magnet compound is in contact with the joining surface.

11. A method for manufacturing a molded product as described in claim 10, wherein the joining process comprises: a coating process for forming a resin film containing the same resin as that contained in the bonded magnet on the joining surface; and a molding process for compression molding the bonded magnet compound while the bonded magnet compound is in contact with the resin film.

12. The method for manufacturing a molded product according to claim 11, wherein in the coating step, a resin solution containing the same resin as that contained in the bonded magnet is applied to the joining surface, and the resin solution is dried.

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