JP2020053590A - Yoke-integrated bonded magnet and manufacturing method thereof - Google Patents

Abstract

To provide a yoke-integrated bonded magnet having a high bonding strength between a bond magnet and a cup-shaped yoke, and a manufacturing method of the yoke-integrated bonded magnet by compression molding.SOLUTION: In a yoke-integrated bonded magnet in which a bond magnet is integrally provided on the outer peripheral surface 2a of a cup-shaped yoke 2 having a bottomed cylindrical shape, a ridge 2c is formed on the outer peripheral surface 2a of the yoke 2 so as to extend over the entire area or a partial area in the circumferential direction, and notches 2d are formed at a plurality of locations on the ridge 2c.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a yoke-integrated bond magnet in which a cup-shaped yoke is integrated with a bond magnet, and a method for manufacturing the yoke-integrated bond magnet using a molding apparatus.

  Bonded magnets formed by solidifying magnetic powder and a resin as a binder for the magnetic powder have the advantages of higher dimensional accuracy and higher degree of freedom in shape than sintered magnets. A yoke-integrated bond magnet obtained by integrally providing such a cylindrical bond magnet on the outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape is used for various motors in electronic devices, cameras, automobiles, and the like. I have.

  Patent Documents 1 and 2 disclose such a yoke-integrated bonded magnet and a method for manufacturing the same. In Patent Literature 1, a bond magnet is integrally molded on an outer peripheral surface of a cup-shaped yoke provided with a concave portion. In Patent Literature 2, a flange is annularly provided on an outer edge of a cup-shaped yoke, and a bond magnet is integrally provided on an outer periphery of the flange. In each of Patent Documents 1 and 2, a bond magnet is formed on a yoke by injection molding.

Japanese Utility Model Publication No. 60-147980 JP-A-8-23668

  In the yoke-integrated bond magnet, the bond strength between the bond magnet and the cup-shaped yoke is reduced, and the bond magnet may be separated from the yoke. When the bond magnet separates from the yoke, problems such as the bond magnet moving in the axial direction of the yoke and the bond magnet rotating relative to the yoke occur. Therefore, improvement of the bond strength between the bond magnet and the yoke in the yoke-integrated bond magnet is an issue.

  SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has a high yoke-integrated bond magnet having a high bonding strength between a bond magnet and a cup-shaped yoke, and a yoke for manufacturing the yoke-integrated bond magnet by compression molding. An object of the present invention is to provide a method for manufacturing an integrated bond magnet.

  The yoke-integrated bond magnet according to the present invention is a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape. A ridge extending over the entire area or a part of the yoke in the circumferential direction is formed, and cutouts are formed at a plurality of positions of the ridge.

  In the present invention, on the outer peripheral surface of the yoke, a ridge extending over the entire area or a part of the area in the circumferential direction is formed. Therefore, the bond strength between the bond magnet and the yoke in the axial direction is high, and the problem that the bond magnet moves in the axial direction of the yoke does not occur. Notches are formed at a plurality of locations of the ridge. Therefore, the bond strength between the bond magnet and the yoke in the circumferential direction is high, and the problem that the bond magnet rotates relatively to the yoke does not occur.

  The yoke-integrated bond magnet according to the present invention is a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape. A first groove extending over the entire area or a partial area of the yoke in the circumferential direction is formed, and a plurality of second grooves extending along the axial length direction of the yoke are formed on the outer peripheral surface of the yoke. It is characterized by having.

  In the present invention, the first groove portion is formed on the outer peripheral surface of the yoke so as to extend over the entire area or a part of the area in the circumferential direction. Therefore, the bond strength between the bond magnet and the yoke in the axial direction is high, and the problem that the bond magnet moves in the axial direction of the yoke does not occur. Further, a plurality of second grooves extending in the axial direction are formed on the outer peripheral surface of the yoke. Therefore, the bond strength between the bond magnet and the yoke in the circumferential direction is high, and the problem that the bond magnet rotates relatively to the yoke does not occur.

  The yoke-integrated bond magnet according to the present invention is a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape. It is characterized in that a through-hole penetrating in the radial direction of the yoke is formed.

  According to the present invention, a through hole is formed in a side portion of the yoke so as to penetrate in a radial direction. Therefore, the bond strength between the bond magnet and the yoke is high, and problems such as the bond magnet moving in the axial direction of the yoke and the bond magnet rotating relative to the yoke do not occur.

  The manufacturing method of the yoke-integrated bond magnet according to the present invention is a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape by using a molding apparatus. In the manufacturing method, a ridge extending over the entire area or a part of the circumferential direction is formed on the outer peripheral surface, and a cup shape having a bottomed cylindrical shape in which notches are formed at a plurality of locations of the ridge. Placing the yoke in the molding apparatus, compressing a mixture of magnetic powder and resin with the yoke in the molding apparatus to produce a molded body, and placing the produced molded body in the molding apparatus. Using a springback of the mixture generated when the mixture is extracted from the yoke, to integrate the mixture and the yoke.

  In the present invention, a mixture of a magnetic powder and a resin, a ridge extending over the entire area or a partial area in the circumferential direction is formed on the outer peripheral surface, and cutouts are formed at a plurality of locations of the ridge. The mixture and the yoke are integrated using the stress generated by springback of the mixture with respect to the yoke, which is generated when the molded body produced by compression-molding the yoke is extracted from the molding apparatus. Therefore, a yoke-integrated bond magnet having a high bond strength between the bond magnet and the yoke is manufactured through a simple manufacturing process.

  The manufacturing method of the yoke-integrated bond magnet according to the present invention is a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape by using a molding apparatus. In the manufacturing method, a ridge extending over the entire area or a part of the circumferential direction is formed on the outer peripheral surface, and a cup shape having a bottomed cylindrical shape in which notches are formed at a plurality of locations of the ridge. The step of disposing the yoke in the molding apparatus, the step of compressing and molding the magnetic powder with the yoke in the molding apparatus to produce a molded body, and the step of extracting the produced molded body from the molding apparatus A step of integrating the magnetic powder and the yoke by utilizing a springback of the magnetic powder to the yoke, and a step of impregnating the anaerobic resin into the molded body by a pressure impregnation method. Having And it features.

  In the present invention, a magnetic powder and a yoke having a ridge extending over the entire circumferential area or a partial area on the outer peripheral surface and notches formed at a plurality of locations of the ridge are provided. The magnetic powder and the yoke are integrated by utilizing the stress generated by springback of the yoke of the magnetic powder generated when the compact produced by compression molding is extracted from the molding apparatus. Therefore, a yoke-integrated bond magnet having a high bond strength between the bond magnet and the yoke is manufactured through a simple manufacturing process. In addition, after the anaerobic resin was soaked in the molded body, the excess anaerobic resin exposed to the air can be easily removed by washing or the like, so that the filling ratio of the magnetic powder was increased while maintaining high strength. Manufactures a yoke-integrated bonded magnet.

  The manufacturing method of the yoke-integrated bond magnet according to the present invention is a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape by using a molding apparatus. In the manufacturing method, a bottomed cylinder in which an outer peripheral surface is formed with a first groove extending over the entire area or a partial area in a circumferential direction and a plurality of second grooves extending along an axial length direction. Disposing a cup-shaped yoke in the molding apparatus, forming a mixture of the magnetic powder and the resin in the molding apparatus by compression molding with the yoke, and forming the molded body; Integrating the mixture and the yoke by utilizing springback of the mixture with respect to the yoke generated when the body is extracted from the molding device.

  According to the present invention, a mixture of a magnetic powder and a resin, a first groove extending over the entire circumferential area or a partial area on the outer peripheral surface, and a plurality of second grooves extending along the axial direction are provided. The mixture and the yoke are integrated by utilizing the stress generated by the spring back of the mixture with respect to the yoke generated when the molded body produced by compression-molding the yoke having the above-mentioned is formed from the molding apparatus. Therefore, a yoke-integrated bond magnet having a high bond strength between the bond magnet and the yoke is manufactured through a simple manufacturing process.

  The manufacturing method of the yoke-integrated bond magnet according to the present invention is a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape by using a molding apparatus. In the manufacturing method, a bottomed cylinder in which an outer peripheral surface is formed with a first groove extending over the entire area or a partial area in a circumferential direction and a plurality of second grooves extending along an axial length direction. Disposing a cup-shaped yoke in the molding device, forming a compact by compressing magnetic powder with the yoke in the molding device, and forming the molded product in the molding device. A step of integrating the magnetic powder and the yoke using spring back of the magnetic powder generated when the magnetic powder is extracted from the apparatus, and immersing an anaerobic resin in the molded body by a pressure impregnation method. Process Characterized in that it.

  In the present invention, a magnetic powder, a first groove portion extending over the entire region or a partial region in the circumferential direction, and a plurality of second groove portions extending along the axial direction are formed on the outer peripheral surface. The magnetic powder and the yoke are integrated by utilizing the stress generated by the spring back of the yoke of the magnetic powder, which is generated when the molded body produced by compression molding of the yoke is extracted from the molding apparatus. Therefore, a yoke-integrated bond magnet having a high bond strength between the bond magnet and the yoke is manufactured through a simple manufacturing process. In addition, after the anaerobic resin was soaked in the molded body, the excess anaerobic resin exposed to the air can be easily removed by washing or the like, so that the filling ratio of the magnetic powder was increased while maintaining high strength. Manufactures a yoke-integrated bonded magnet.

  According to the yoke-integrated bond magnet of the present invention, the bond strength between the bond magnet and the yoke is high, so that the bond magnet moves in the axial direction of the yoke, or the bond magnet moves relative to the yoke. It is possible to suppress the occurrence of such a problem that the rotation is caused. According to the method of manufacturing a yoke-integrated bond magnet of the present invention, the bond magnet and the yoke are integrated using springback when the molded body is pulled out of the molding apparatus. The combined yoke-integrated bond magnet can be easily manufactured.

It is a perspective view which shows a yoke integral-type bond magnet. It is sectional drawing which shows the yoke integral type | mold bond magnet of 1st Embodiment. It is a perspective view showing a yoke in a yoke integral type bond magnet of a 1st embodiment. It is sectional drawing which shows the process sequence of the manufacturing method of the yoke integral type | mold bonded magnet of 1st Embodiment. It is sectional drawing which shows the process sequence of the manufacturing method of the yoke integral type | mold bonded magnet of 1st Embodiment. It is sectional drawing which shows the process sequence of the manufacturing method of the yoke integral type | mold bonded magnet of 1st Embodiment. It is sectional drawing which shows the process sequence of the manufacturing method of the yoke integral type | mold bonded magnet of 1st Embodiment. It is a figure showing the example of the section shape of a notch. It is sectional drawing which shows the shape inside / outside of the upper mold | die and the lower mold | die of the molded object in the manufacturing method of a yoke integral type bond magnet. It is sectional drawing which shows the yoke integral type | mold bond magnet of 2nd Embodiment. It is a perspective view showing a yoke in a yoke integral type bond magnet of a 2nd embodiment. It is sectional drawing which shows the yoke integral-type bond magnet of 3rd Embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments.

(First embodiment)
FIG. 1 is a perspective view showing a yoke-integrated bond magnet. The yoke-integrated bond magnet 1 is configured by integrating a cup-shaped yoke 2 having a bottomed cylindrical shape and a cylindrical bond magnet 3. Due to the difference in the shape of the yoke 2, the yoke-integrated bond magnet 1 of the present invention includes a first embodiment and second and third embodiments described later.

  FIG. 2 is a sectional view showing the yoke-integrated bond magnet 1 of the first embodiment, and FIG. 3 is a perspective view showing the yoke 2 of the yoke-integrated bond magnet 1 of the first embodiment. The cup-shaped yoke 2 has a bottomed cylindrical shape, and a cylindrical bonded magnet 3 is integrally provided on an outer peripheral surface (outer surface) 2a.

  In the yoke 2, for example, the outer diameter, the inner diameter, the thickness of the side surface, the entire length, the length of the hollow portion, and the thickness of the bottom portion 2b are 34 mm, 29 mm, 2.5 mm, 13.5 mm, and 11 mm, respectively. , 2.5 mm. And, for example, the length, outer diameter, and inner diameter of the bonded magnet 3 are 11 mm, 40 mm, and 34 mm, respectively (see FIG. 2).

  On the outer peripheral surface 2a at the center in the axial length direction of the yoke 2, one ridge 2c extending over the entire area in the circumferential direction is formed. Four notches 2d are formed in the ridge 2c in such a manner that four notches are arranged in the circumferential direction of the yoke 2. For example, the width and height of the ridge 2c are 2 mm and 1 mm, respectively, and the length and depth of each notch 2d are 6 mm and 0.5 mm, respectively. A circular positioning hole 2e is formed in the center of the bottom 2b of the yoke 2.

  The dimensions of each part of the yoke 2 and the dimensions of the bond magnet 3 described above are merely examples, and these dimensions may be appropriately set according to the required specifications.

  As a material of the yoke 2, an iron material (forged product, press-formed product of a plate material), silicon steel, magnetic stainless steel, or the like can be used, and a resin or a composite material of a resin and a metal powder or an alloy powder may be used.

  The bonded magnet 3 is formed from a mixture (magnetic composition) of a magnetic powder and a resin. As the magnetic powder, rare earth magnetic powder, ferrite magnetic powder and the like can be used. As the rare earth magnetic powder, an RTB magnetic powder (R is at least one kind of rare earth element and always contains one of Nd and Pr, T is Fe or Fe and Co, and B is boron And R-T-N-based magnetic powder (R is at least one rare earth element and always contains Sm, T is an iron group element, and N is nitrogen), etc. Is mentioned. The shape of the RTB-based magnetic powder is preferably flat (for example, the shape aspect ratio of powder particles = minor axis / major axis is 0.3 or less). The use of the RTB-based magnetic powder having a flat shape facilitates lamination of the magnetic powder during compression molding of a material (a mixture of a magnetic powder and a resin). In addition, voids or resin pools are hardly formed between the magnetic powders during molding, and high-density packing becomes possible. The average particle size of the RTB-based magnetic powder is preferably 20 μm or more and 300 μm or less, more preferably 40 μm or more and 250 μm or less. Here, the average particle diameter is the arithmetic average diameter of the volume distribution, and is measured using a laser diffraction type particle size distribution analyzer.

  On the other hand, the resin used for the bond magnet 3 is a thermosetting resin used for general bond magnets, and preferable resins include, for example, epoxy resin, phenol resin, and polyimide resin.

The density of the bonded magnet 3 is 5.8 to 6.2 g / cm ³ . Since the yoke-integrated bond magnet 1 of the present invention is manufactured by compression molding as described later, the yoke-integrated bond magnet manufactured by injection molding (generally has a density of 5.0 to 5.5 g / cm ^3). ), The density is high (because the amount of magnetic powder per unit volume is large), so that excellent magnetic properties can be expected.

  Hereinafter, a method of manufacturing the above-described yoke-integrated bond magnet 1 by compression molding will be described. FIG. 4 to FIG. 7 are cross-sectional views illustrating the steps of a method of manufacturing the yoke-integrated bond magnet 1 according to the first embodiment.

  FIG. 4A shows a starting position (hereinafter, referred to as “fixed position”) of a molding operation of a molding device used in a manufacturing process. The molding apparatus includes a cylindrical die 10, an upper mold 20, and a lower mold 30.

  The upper mold 20 includes a long cylindrical first upper punch 21 having an outer diameter substantially equal to the inner diameter of the die 10 and a long cylindrical second upper punch 21 having an outer diameter substantially equal to the inner diameter of the first upper punch 21. It has a triple configuration including an upper punch 22 and a long cylindrical upper core 23 having a diameter substantially equal to the inner diameter of the second upper punch 22, and can be inserted through the die 10 from above. The lower end of the upper core 23 has a shape following the internal shape of the yoke 2. The first upper punch 21 can be inserted vertically in the die 10, the second upper punch 22 can be inserted vertically in the first upper punch 21, and the upper core 23 can be inserted in the second upper punch 22. Can be inserted vertically. The movement (up / down) of the first upper punch 21, the movement (up / down) of the second upper punch 22, and the movement (up / down) of the upper core 23 can be performed independently of each other.

  The lower mold 30 includes a long cylindrical first lower punch 31 having an outer diameter substantially equal to the inner diameter of the die 10, and a long cylindrical first lower punch 31 having an outer diameter substantially equal to the inner diameter of the first lower punch 31. A second lower punch 32, a long cylindrical third lower punch 33 having an outer diameter substantially equal to the inner diameter of the second lower punch 32, and a long cylindrical column having a diameter substantially equal to the inner diameter of the third lower punch 33; This is a quadruple configuration including the lower core 34, and can be inserted through the die 10 from below. The first lower punch 31 can be inserted vertically in the die 10, the second lower punch 32 can be inserted vertically in the first lower punch 31, and the third lower punch 33 can be inserted in the second lower punch 33. The lower core 34 can be inserted vertically through the third lower punch 33. The movement (up / down) of the first lower punch 31, the movement (up / down) of the second lower punch 32, the movement (up / down) of the third lower punch 33, and the movement (up / down) of the lower core 34. Lowering) can be performed independently of each other.

  First, as shown in FIG. 4B, the material 42 of the bond magnet 3 (magnetic powder and thermosetting resin) is placed in a space 41 formed between the second lower punch 32 and the die 10 by lowering the first lower punch 31. Mixture). The descending distance d (depth of the space 41) at this time is determined in consideration of the length of the bonded magnet 3 in the manufactured yoke-integrated bonded magnet 1 and the compression ratio of the material 42 in a compression molding process described later. Is done.

  Next, as shown in FIG. 4C, after lowering the lower core 34, the previously prepared yoke 2 as shown in FIG. 3 is placed so that the bottom 2b is placed on the third lower punch 33. It is arranged in a molding device. Here, the positioning hole 2e formed in the bottom 2b of the yoke 2 functions as a positioning element for placing the yoke 2 at a regular position.

  Next, as shown in FIG. 5A, the first upper punch 21, the second upper punch 22, and the upper core 23 are lowered, and the yoke 2 is fixed by the upper core 23.

  Next, as shown in FIG. 5B, while lowering the second lower punch 32 and the third lower punch 33, lowering the first upper punch 21, the second upper punch 22 and the upper core 23, the yoke 2 is moved to the die 10 Then, the material 42 is brought into contact with the outer peripheral surface of the yoke 2.

  Next, as shown in FIG. 5C, the second lower punch 32 and the second upper punch 22 are lowered to adjust the contact area between the material 42 and the yoke 2.

  Next, as shown in FIG. 6A, the first upper punch 21 is lowered, and the first lower punch 31 is raised. Here, the descending amount of the first upper punch 21 is adjusted so that the first upper punch 21 and the second upper punch 22 have the same height position on the surface in contact with the material 42. Further, the amount of elevation of the first lower punch 31 is adjusted so that the height positions of the surfaces of the first lower punch 31 and the second lower punch 32 that are in contact with the material 42 are the same. As a result, the yoke 2 and the material 42 are sealed by the upper mold 20 and the lower mold 30.

  Next, as shown in FIG. 6B, the material 42 is pressed by the first upper punch 21 and the second upper punch 22 and the first lower punch 31 and the second lower punch 32 from two directions, a lower direction and an upper direction. , The yoke 2 and the material 42 are integrally formed.

  Next, as shown in FIG. 6C, the bond magnet (compressed body of the material 42) is held between the first upper punch 21 and the second upper punch 22, and the first lower punch 31 and the second lower punch 32, and the upper core is pressed. The first upper punch 21, the second upper punch 22, the upper core 23, the first lower punch 31, the second lower punch 32, and the third lower punch 33 are held while the yoke 2 is sandwiched between the lower punch 23 and the third lower punch 33. To raise. As a result, the upper end positions of the first lower punch 31 and the second lower punch 32 coincide with the upper end position of the die 10, and the bond magnet is located outside the die 10.

  Next, as shown in FIG. 7A, the first upper punch 21, the second upper punch 22, and the upper core 23 are further raised and returned to the home position.

  Next, as shown in FIG. 7B, the third lower punch 33 and the lower core 34 are raised and returned to the home position. As a result, the upper end positions of the third lower punch 33 and the lower core 34 coincide with the upper end positions of the die 10, and the molded body 43 is located outside the die 10. Thereafter, the molded body 43 is removed from the die 10, and the molding process is completed.

  Since the resin is not cured in the removed molded body 43, the removed molded body 43 is subjected to a heat treatment at, for example, 200 ° C. for one hour to cure the resin. Thereby, the yoke-integrated bond magnet 1 having a desired density and shape is obtained.

  In the above-described embodiment, the bond magnet 3 is made of a mixture (compound) of the magnetic powder and the thermosetting resin. However, the bond magnet 3 may contain the magnetic powder and the anaerobic resin. May be configured. The procedure for manufacturing the yoke-integrated bonded magnet 1 in this case will be briefly described below.

  According to the procedure shown in FIGS. 4 to 7 as described above, a compact is produced by integrally compressing the magnetic powder into the yoke 2. Here, in the process shown in FIG. 4B, the only difference is that, for example, an RTN-based magnetic powder is used as the material 42 to be filled in the space 41 instead of the mixture of the magnetic powder and the thermosetting resin. Since the other steps are the same as those described above, the description thereof will be omitted.

  The low-viscosity anaerobic resin is impregnated into the compact after the compression molding using an impregnation method, and is left as it is. After standing, excess anaerobic resin is removed by washing. Here, since it has anaerobic properties, only the anaerobic resin inside and on the surface layer is hardened, so that excess anaerobic resin that has come into contact with the other air can be easily and quickly removed by washing. Next, the molded body impregnated with the anaerobic resin is subjected to a heat treatment at about 150 to 180 ° C. to completely cure the anaerobic resin, and the yoke-integrated type having the bonded magnet 3 containing the magnetic powder and the anaerobic resin. The bonded magnet 1 is manufactured. For the impregnation, a known method such as a reduced pressure method and a pressurized method may be applied.

  With such a configuration including the magnetic powder and the anaerobic resin, it is possible to provide the yoke-integrated bond magnet 1 having a high filling ratio of the magnetic powder and a small variation in strength, and to improve the magnetic characteristics.

  In the manufacturing procedure of the yoke-integrated bonded magnet 1 described above, a lubricant may be added to the mixture of the magnetic powder and the thermosetting resin or the material 42 that is only the magnetic powder. By adding such a lubricant, friction between the material 42 and the die 10 is reduced, and the life of the molding apparatus can be extended.

  Hereinafter, the bond strength between the bond magnet 3 and the yoke 2 in the above-described yoke-integrated bond magnet 1 will be described.

  As described above, one ridge 2c is formed on the outer peripheral surface 2a of the yoke 2 over the entire area in the circumferential direction, and four ridges 2c are arranged on the ridge 2c in the circumferential direction of the yoke 2. , Four notches 2d are formed.

  Due to the stress generated by the springback, a strong connection between the material 42 and the yoke 2 is realized by the ridge 2c, so that the bond strength between the bond magnet 3 and the yoke 2 in the axial direction is increased, and the yoke-integrated bond is formed. In the magnet 1, there is no problem that the bond magnet 3 moves in the axial direction of the yoke 2. Thus, the formation of the ridge 2c is a measure against the thrust load.

  FIG. 8 is a diagram illustrating an example of the cross-sectional shape of the notch 2d. In FIG. 8, A shows an example in which the cross section has a rectangular shape, B shows an example in which the bottom side is wider than the front side (the shape of a groove), and C shows an example in which the bottom side is narrower than the front side (taper). State).

  FIG. 9 is a cross-sectional view showing the shape of the molded body 43 inside / outside the upper mold 20 and the lower mold 30 in the above-described method for manufacturing the yoke-integrated bond magnet 1. FIG. FIG. 9B shows the shape outside the mold. The cross-sectional shape of the notch 2d is a rectangular shape as shown in FIG. 8A.

  When the molded body 43 is removed from the mold, the material 42, which is a mixture of the magnetic powder and the resin, generates a stress (see the arrow in FIG. 9B) generated by spring back of the material 42 with the notch 2d. A strong connection with the yoke 2 is realized. As a result, the bond strength between the bond magnet 3 and the yoke 2 in the circumferential direction is increased, and in the yoke-integrated bond magnet 1, there is no problem that the bond magnet 3 rotates relative to the yoke 2. Thus, the formation of the notch 2d is a measure against slip torque.

  Even when the cross-sectional shape of the notch 2d is not a rectangular shape as described above (see FIG. 8A) but a dovetail shape as shown in FIG. In the bonded magnet 1, it is possible to realize a high bonding strength between the bonded magnet 3 and the yoke 2 in the circumferential direction. On the other hand, when the cross-sectional shape of the notch 2d is tapered as shown in FIG. 8C, the stress from the material 42 due to the springback is not sufficiently applied to the yoke 2 and escapes to the material 42 side. Therefore, high bonding strength between the bond magnet 3 and the yoke 2 cannot be expected. From the above, the cross-sectional shape of the notch 2d is preferably a rectangular shape as shown in FIG. 8A or a dovetail shape as shown in FIG. 8B, and a tapered shape as shown in FIG. 8C is inappropriate.

  In the first embodiment described above, the ridge 2c extends over the entire area of the yoke 2 in the circumferential direction. However, the present invention is not limited to this, and the ridge 2c extends over a part of the yoke 2 in the circumferential direction. The ridge 2c may be formed. Further, although one ridge 2c is formed, the present invention is not limited to this, and a plurality of ridges 2c may be extended over the entire area or a part of the yoke 2 in the circumferential direction. .

  In the first embodiment described above, the cutouts 2d are formed at four places of the ridge 2c, but the number of cutouts 2d is not limited to four.

(Second embodiment)
FIG. 10 is a cross-sectional view showing the yoke-integrated bond magnet 1 of the second embodiment. FIG. 11 is a perspective view showing the yoke 2 of the yoke-integrated bond magnet 1 of the second embodiment.

  The cup-shaped yoke 2 has a bottomed cylindrical shape as a whole similarly to the first embodiment, and a cylindrical bond magnet 3 is integrally provided on an outer peripheral surface (outer surface) 2a. The overall shape of the yoke 2 is the same as that of the first embodiment. For example, the outer diameter, the inner diameter, the thickness of the side surface, the entire length, the length of the hollow portion, and the thickness of the bottom portion 2b are 34 mm, respectively. 29 mm, 2.5 mm, 13.5 mm, 11 mm, and 2.5 mm. For example, the length, outer diameter, and inner diameter of the bonded magnet 3 are 11 mm, 40 mm, and 34 mm, respectively (see FIG. 10). A positioning hole 2e is formed at the center of the bottom 2b.

  In the second embodiment, one first groove 2f extending over the entire circumferential direction is formed on the outer peripheral surface 2a at the center of the yoke 2 in the axial length direction. Further, four second grooves 2g extending in the axial direction are formed on the outer peripheral surface 2a at the center in the axial direction of the yoke 2 in such a manner as to be equally spaced in the circumferential direction. The first groove 2f intersects each of the four second grooves 2g. For example, the width and depth of the first groove 2f are 2 mm and 0.5 mm, respectively, and the length, width and depth of each second groove 2g are 6 mm, 2 mm and 0.5 mm, respectively. The dimensions of each part of the yoke 2 and the dimensions of the bond magnet 3 described above are merely examples, and these dimensions may be appropriately set according to the required specifications.

  Like the notch 2d of the first embodiment, the cross-sectional shape of the first groove 2f and the second groove 2g is preferably a rectangular shape as shown in FIG. 8A or a dovetail shape as shown in FIG. 8B. The tapered shape shown in FIG.

The materials of the yoke 2 and the bond magnet 3 are the same as those of the first embodiment. The density of the bonded magnet 3 is 5.8 to 6.2 g / cm ³ , as in the first embodiment.

  In the yoke-integrated bond magnet 1 of the second embodiment, one first groove 2f extending over the entire circumferential direction is formed on the outer peripheral surface 2a of the yoke 2. Accordingly, the bonding strength between the bond magnet 3 and the yoke 2 in the axial direction is increased by the first groove 2f, so that the bond magnet 3 moves in the axial direction of the yoke 2 in the yoke-integrated bond magnet 1. No trouble occurs. Thus, in the second embodiment, the formation of the first groove 2f is a measure against the thrust load.

  Further, in the yoke-integrated bond magnet 1 of the second embodiment, four second grooves 2 g extending in the axial direction are formed on the outer peripheral surface 2 a of the yoke 2. Therefore, since the bond strength between the bond magnet 3 and the yoke 2 in the circumferential direction is increased, in the yoke-integrated bond magnet 1, a problem that the bond magnet 3 relatively rotates with respect to the yoke 2 does not occur. Thus, in the second embodiment, the formation of the second groove 2g is a measure against slip torque.

  The procedure for manufacturing the yoke-integrated bond magnet 1 according to the second embodiment is the same as the procedure for manufacturing the yoke-integrated bond magnet 1 according to the above-described first embodiment, and a description thereof will be omitted.

  The first groove 2f extends over the entire area of the yoke 2 in the circumferential direction. However, the present invention is not limited to this, and the first groove 2f is formed over a part of the yoke 2 in the circumferential direction. You may. Further, although one first groove 2f is formed, the present invention is not limited to this, and a plurality of first grooves 2f may extend in the circumferential direction of the yoke 2.

  Further, the second groove portion 2g is formed at four locations on the outer peripheral surface 2a of the yoke 2, but is not limited to this, and is provided at two, three, or five or more locations in the circumferential direction in the axial direction. The extending second groove 2g may be formed.

(Third embodiment)
FIG. 12 is a sectional view showing the yoke-integrated bond magnet 1 according to the third embodiment. The overall shape of the yoke 2 in the yoke-integrated bond magnet 1 of the third embodiment is a bottomed cylindrical shape as in the first and second embodiments described above, but in the third embodiment, Instead of the ridge 2c and the notch 2d, the first groove 2f, and the second groove 2g, two through holes 2h are formed in the yoke 2 so as to radially penetrate the side portions at positions separated by 180 degrees in the circumferential direction. Have been. For example, the cross section of each through hole 2h is a circle having a diameter of 2 mm, and the length of each through hole 2h is 2.5 mm.

The materials of the yoke 2 and the bond magnet 3 are the same as those of the first embodiment described above, and the density of the bond magnet 3 is 5.8 to 6.2 g / cm ³ , as in the first embodiment. is there.

  In the third embodiment, since the through hole 2h is formed in the side portion of the yoke 2, the bond strength between the bond magnet 3 and the yoke 2 is increased, and the bond magnet 3 may move in the axial direction of the yoke 2. In addition, it is possible to prevent such a problem that the bond magnet 3 rotates relative to the yoke 2.

  The procedure for manufacturing the yoke-integrated bond magnet 1 according to the third embodiment is the same as the procedure for manufacturing the yoke-integrated bond magnet 1 according to the above-described first embodiment, and a description thereof will be omitted.

  Note that the number of through holes 2h formed in the yoke 2 is not limited to one pair, but may be a plurality of pairs. Further, the cross-sectional shape of the through hole 2h is not limited to a circle, but may be a rectangle.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

REFERENCE SIGNS LIST 1 yoke integrated bond magnet 2 yoke 2 a outer peripheral surface 2 b bottom 2 c ridge 2 d cutout 2 e positioning hole 2 f first groove 2 g second groove 2 h through hole 3 bond magnet 10 die 20 upper mold 30 lower mold 42 material 43 Molded body

Claims (7)

In a yoke-integrated bond magnet in which a bond magnet is integrally provided on the outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape,
A yoke, wherein a ridge extending over the entire area or a part of the yoke in the circumferential direction is formed on an outer peripheral surface of the yoke, and cutouts are formed at a plurality of positions of the ridge. Integrated bond magnet. In a yoke-integrated bond magnet in which a bond magnet is integrally provided on the outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape,
A first groove portion is formed on the outer peripheral surface of the yoke over the entire area or a partial area in the circumferential direction of the yoke, and extends on the outer peripheral surface of the yoke along the axial length direction of the yoke. A yoke-integrated bond magnet, wherein a plurality of second grooves are formed. In a yoke-integrated bond magnet in which a bond magnet is integrally provided on the outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape,
A yoke-integrated bond magnet, wherein a through hole is formed in a side portion of the yoke in a radial direction of the yoke. In a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape using a molding apparatus,
A ridge extending over the entire area or a partial area in the circumferential direction is formed on the outer peripheral surface, and a cup-shaped yoke having a bottomed cylindrical shape in which cutouts are formed at a plurality of positions of the ridge, Arranging in a molding device;
In the molding apparatus, a step of compression molding a mixture of a magnetic powder and a resin with the yoke to produce a molded body,
Using a springback for the yoke of the mixture generated when the produced molded body is extracted from the molding apparatus, and integrating the mixture and the yoke. Production method. In a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape using a molding apparatus,
A ridge extending over the entire area or a partial area in the circumferential direction is formed on the outer peripheral surface, and a cup-shaped yoke having a bottomed cylindrical shape in which cutouts are formed at a plurality of positions of the ridge, Arranging in a molding device;
In the molding apparatus, a step of compression molding magnetic powder with the yoke to produce a molded body,
Utilizing a springback for the yoke of the magnetic powder, which is generated when the formed compact is extracted from the molding apparatus, a step of integrating the magnetic powder and the yoke,
A step of impregnating an anaerobic resin into the molded body by a pressure impregnation method. In a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape using a molding apparatus,
A cylindrical cup with a bottom having a first groove extending over the entire area or a partial area in the circumferential direction and a plurality of second grooves extending along the axial direction formed on the outer peripheral surface. Disposing a yoke in the molding device;
In the molding apparatus, a step of compression molding a mixture of a magnetic powder and a resin with the yoke to produce a molded body,
Using a springback for the yoke of the mixture generated when the produced molded body is extracted from the molding apparatus, and integrating the mixture and the yoke. Production method. In a method of manufacturing a yoke-integrated bond magnet in which a bond magnet is integrally provided on an outer peripheral surface of a cup-shaped yoke having a bottomed cylindrical shape using a molding apparatus,
A cylindrical cup with a bottom having a first groove extending over the entire area or a partial area in the circumferential direction and a plurality of second grooves extending along the axial direction formed on the outer peripheral surface. Disposing a yoke in the molding device;
In the molding apparatus, a step of compression molding magnetic powder with the yoke to produce a molded body,
Utilizing a springback for the yoke of the magnetic powder, which is generated when the formed compact is extracted from the molding apparatus, a step of integrating the magnetic powder and the yoke,
A step of impregnating an anaerobic resin into the molded body by a pressure impregnation method.

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