JP2017177254A - Sinter body form processing method and processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a form processing method capable of achieving higher processing accuracy compared with conventional methods as well as suitably being used for form processing of sinter bodies in a small quantity large variety production.SOLUTION: A sinter body form processing method comprises the steps for: (Sa) providing a sinter body including a first main surface SO in a convex shape and a second main surface on a side opposite to the first main surface SO; (Sb1) forming at least one of a first reference surface formed by partially grinding the first main surface SO of the sinter body, and at least one second reference surface formed by grinding at least partially the second main surface SI; (Sc) fixing the sinter body so that the first reference surface or the at least one second reference surface comes in contact with a first jig; and (Sd) processing the first main surface SO to have a convex curved surface, or the second man surface SI to have a convex curved surface or a flat surface, by grinding the sinter body using a rotating first grinding wheel, in a state of the sinter body fixed in the step Sc.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a shape processing method and a processing apparatus for a sintered body, and more particularly to a shape processing method and a processing apparatus suitably used for shape processing of a rare earth sintered magnet.

  Permanent magnets (hereinafter simply referred to as “magnets”) are used as magnets of various shapes. Rare earth magnets have excellent magnetic properties and are widely used. Among them, an RTB-based sintered magnet known as a neodymium magnet (R is a rare earth element and T is a transition metal element that always contains Fe) has excellent magnetic properties and relatively low material costs. Widely used.

  The magnet of the RTB-based sintered magnet is manufactured by the following method. In the present specification, a magnet that is not magnetized is also called a magnet.

  An RTB-based alloy powder having a desired composition is prepared. A compact with a desired shape is obtained by press molding the alloy powder. A sintered body is obtained by sintering the compact. If necessary, the sintered body is subjected to a heat treatment such as so-called aging treatment. Before or after heat treatment, it is machined into a magnet of the desired size and shape. Thereafter, the magnet is washed to remove grinding powder and grinding fluid (cooling fluid) generated by machining and adhering to the magnet surface. Thereafter, various surface treatments may be performed for the purpose of improving corrosion resistance.

  In order to improve the manufacturing efficiency of the RTB-based sintered magnet and the yield of the material, an attempt to produce a molded body having a shape close to the final magnet shape (sometimes referred to as “net shape”). Has been made. For example, Patent Document 1 discloses a method for manufacturing a rare earth sintered magnet having a kamaboko shape and a tile shape (also referred to as an arc shape or a C shape). Patent Document 2 discloses a method for efficiently processing a magnet into a desired shape (for example, a tile shape).

JP 2006-278919 A JP 11-347900 A

  In recent years, with the improvement in performance of motors and the like, requirements for the accuracy of the shape and dimensions of magnets have become strict. In addition, it is desired to develop a processing method that can easily cope with processing of a small variety of magnets. Here, the shape processing of the sintered magnet has been described. However, the present invention is not limited to this, and the same problem occurs in the shape processing of a ceramic sintered body such as ferrite.

  An object of the present invention is to provide a shape processing method that can achieve higher processing accuracy than the prior art, and that is preferably used for shape processing of a small number of various types of sintered bodies, and a processing apparatus that is preferably used for the method. It is in.

  According to an embodiment of the present invention, a method for processing a shape of a sintered body includes a step a for preparing a sintered body having a convex first main surface and a second main surface opposite to the first main surface; A first reference surface formed by partially grinding the first main surface of the sintered body, and at least one second reference surface formed by at least partially grinding the second main surface. A step b1 for forming at least one of the above, a step c for fixing the sintered body so that the first reference surface or the at least one second reference surface is in contact with the first jig, In a state where the sintered body is fixed in the step c, the first main surface is processed into a convex curved surface by grinding the sintered body with a rotating first grinding wheel, or the second main surface And d for processing the surface into a concave curved surface or a flat surface. That.

  In one embodiment, the step b1 includes forming both the first reference surface and the at least one second reference surface.

  In one embodiment, the step d includes a step of moving the sintered body in a first direction with respect to the first grinding wheel at a first speed, and the first grinding wheel with respect to the first grinding wheel. Moving in a second direction opposite to the direction at a second speed greater than the first speed. The first speed is, for example, 200 mm / min or more and 500 mm / min or less, and the second speed is, for example, 1000 mm / min or more and 3000 mm / min or less.

  In one embodiment, the step c includes a step of fixing a plurality of the sintered bodies to the first jig in a row.

  In one embodiment, after the step d, the sintering is performed such that at least a part of either the first main surface or the second main surface processed in the step d is in contact with the second jig. The first main surface or the second main surface by grinding the sintered body with a rotating second grinding wheel in a state where the body is fixed e and the sintered body is fixed in the step e. And a step f of processing the other of the above into a predetermined shape.

  In one embodiment, the step f includes a step of grinding the sintered body while moving the sintered body in a third direction at a third speed with respect to the second grinding wheel, and the second grinding wheel. Moving in a fourth direction opposite to the third direction at a fourth speed greater than the third speed. The third speed is, for example, 200 mm / min or more and 500 mm / min or less, and the fourth speed is, for example, 1000 mm / min or more and 3000 mm / min or less.

  In one embodiment, the step e includes a step of fixing a plurality of the sintered bodies to the second jig in a row.

  In one embodiment, the sintered body shape processing method according to any one of the above processes the first main surface into a convex curved surface in the step d. After the step d, the second main surface may be processed into a concave curved surface or a flat surface in the step f. When the second main surface is a flat surface, the step f can be omitted if the second reference surface is formed by grinding the entire second main surface.

  In one embodiment, the second main surface is processed into a concave curved surface or a flat surface in the step d, and the first main surface is processed into a convex curved surface in the step f.

  In one embodiment, the method further includes a step b2 of forming two parallel first side surfaces defining the width of the sintered body between the step a and the step d.

  In one embodiment, the method further includes a step b3 of forming two parallel second side surfaces defining the length of the sintered body between the step a and the step d.

  A processing apparatus according to an embodiment of the present invention is a processing apparatus used in any one of the above-described methods for processing a sintered body, wherein the outer peripheral surface of the disk is a concave curved surface or a convex curved surface with respect to the radial direction. A cantilever grinding unit including a wheel, a motor having a rotation shaft, and a hydraulic bush for fixing the grinding wheel to the rotation shaft of the motor; and a mechanism unit for moving the rotation shaft in the vertical direction.

  In one embodiment, the rotating shaft has a rigidity of 240 N / μm or more.

  According to the embodiments of the present invention, there is provided a shape processing method that can achieve higher processing accuracy than the prior art and is preferably used for shape processing of a small number of various types of sintered bodies, and a processing apparatus that is preferably used for the method. Is done.

It is a flowchart explaining the shape processing method of the sintered compact by embodiment of this invention. (A) is a schematic diagram for demonstrating the process (process Sb1) which forms a 1st reference surface and a 2nd reference surface in the sintered magnet 10a, (b) prescribes | regulates the width | variety of the sintered magnet 10a. It is a schematic diagram for demonstrating the process (process Sb2) which forms the side to perform, (c) is a schematic for demonstrating the process (process Sb3) which forms the side surface which prescribes | regulates the length of the sintered magnet 10a. FIG. (A)-(c) is a figure which shows a mode that the sintered magnet 10a is fixed to the jig | tool 30A for forming a convex curved surface in the sintered magnet 10a, and the jig | tool 30A. (A)-(c) is a figure which shows a mode that the sintered magnet 10a is fixed to the jig | tool 30B for forming a concave curved surface in the sintered magnet 10a, and the jig | tool 30B. (A) is sectional drawing which shows a mode that the sintered magnet 10a is fixed to the jig | tool 30C for forming a concave curved surface in the sintered magnet 10a, (b) is convex to the sintered magnet 10a. It is sectional drawing which shows typically a mode that the sintered magnet 10a is fixed to jig | tool 30D for forming a curved surface. It is a schematic diagram which shows the processing machine 40A provided with the cantilever grinding part for forming a convex curved surface in the sintered magnet 10a. It is a schematic diagram which shows the processing machine 40B provided with the cantilever grinding part for forming a concave curved surface in the sintered magnet 10a. (A)-(c) is a schematic diagram which shows the hydraulic bush 46 with which processing machine 40A or 40B is equipped, (a) is sectional drawing, (b) is a side view, (c) was attached to the rotating shaft 44. It is sectional drawing which shows the mode of time typically. It is a schematic diagram which shows the shape processing method of a comparative example, (a) shows the process of forming a convex curved surface in the sintered magnet 10, (b) is a schematic diagram showing the process of forming a concave curved surface in the sintered magnet 10. FIG. It is a figure which shows typically the processing machine 90 used for the shape process of a comparative example. (A)-(c) is a figure which shows typically the RTB type | system | group sintered magnet 10a-10c in which the shape processing method by embodiment of this invention is used suitably.

  Hereinafter, a method for processing a shape of a sintered body according to an embodiment of the present invention and a processing apparatus suitably used for the method will be described with reference to the drawings. Below, the example which uses a RTB system sintered magnet as a sintered compact is demonstrated. Since the RTB-based sintered magnet has a high processing resistance among the rare earth sintered magnets, if the RTB-based sintered magnet can be processed, other rare earth magnets, ferrite magnets, and other ceramic sintered bodies can be obtained. Can be processed.

  The shape processing method of the sintered body according to the embodiment of the present invention is suitably used for shape processing of the RTB-based sintered magnets 10a to 10c shown in FIGS. These sintered magnets 10a to 10c are magnets used for a motor or the like, and have a convex curved surface (first main surface).

  The sintered magnet 10a includes a convex curved surface (first main surface) SO (outer R surface), a concave curved surface (second main surface) SI (inner R surface), and two side surfaces SW1 parallel to the width direction, It has two side surfaces SL1 parallel to the length direction L1. The first main surface SO and the second main surface SI face each other and are curved in the width direction. The two side surfaces SW1 define a length L1, and the two side surfaces SL1 define a width (maximum width) W1.

  The sintered magnet 10a has a step on the side surface that defines the width, but there are some that do not have a step like the sintered magnet 10b shown in FIG. In addition, there is a case in which a side surface defining the width is inclined like a sintered magnet 10c shown in FIG. Further, the second main surface SI is not necessarily a curved surface but may be a flat surface.

  The thicknesses T1 to T3 of the sintered magnets 10a to 10c are, for example, 7 mm to 12 mm, the widths W1 to W3 are 40 mm to 70 mm, and the lengths L1 to L3 are 50 mm to 70 mm. Is sometimes referred to as “heavy”.) Exceeds 100 g, and the larger one exceeds 200 g.

  In this way, the processing of the shape of a large-sized sintered magnet (single weight exceeding 100 g) has a large processing load. Conventionally, for example, refer to FIGS. 9 (a) and 9 (b). It was done by the method explained.

  First, as shown in FIG. 9A, a plurality of sintered magnets 10 are arranged and fixed on a carbon base plate 82 using an adhesive. The sintered magnet 10 is obtained by sintering a molded body having a shape close to a net shape, has not been subjected to mechanical processing such as grinding after sintering, and has small irregularities on the surface. In addition, the outer shape of the sintered magnet may be distorted due to the density distribution of the compact. Therefore, since such a sintered magnet 10 cannot be directly vacuum-adsorbed, it is fixed on the base plate 82 made of carbon using an adhesive. In addition, before bonding with an adhesive material, the base plate 82 and the sintered magnet 10 are heated in advance. The base plate 82 is fixed on the movable stage 80a by, for example, a vacuum suction method. In this state, the convex curved surface is ground by the grinding wheel 52a while moving the movable stage 80a. Thereafter, the sintered magnet 10 is peeled off from the base plate 82, and the adhesive is removed. Thereafter, as shown in FIG. 9B, the ground convex curved surface is fixed to the movable stage 80b, for example, by vacuum suction, and the concave curved surface is ground by the grinding wheel 52b.

  The above processes are often manual, and it is difficult to avoid variations in accuracy among workers. In addition, since there are a step of attaching using an adhesive and a step of removing, an operation is complicated and throughput is low.

  For the grinding process, for example, a processing machine 90 shown in FIG. 10 is used. The processing machine 90 rotates the three grinding wheels 52 a arranged in parallel with the rotation shaft 94. The processing machine 90 is a double-supported type in which the rotary shaft 94 is supported from both sides via a support portion 92. At the time of grinding, a grinding liquid is supplied to the grinding part. In order to limit the range in which the grinding fluid scatters, the shielding plate 72 is arranged. However, in the double-sided type processing machine 90, as shown in the drawing, the entire mechanical portion of the processing machine 90 is exposed to the grinding liquid. As a result, bearings and the like are easily broken, and failure is likely to occur. Further, in the double-supported type, the replacement work of the grinding wheel is complicated.

  The shape processing method of the sintered magnet according to the embodiment of the present invention solves at least a part of the above-mentioned problems, provides higher processing accuracy than the method of the above-mentioned comparative example, and is a small quantity and a variety of sintered bodies. There are provided a shape processing method suitably used for the shape processing and a processing apparatus suitably used for the method.

  FIG. 1 shows a flowchart of a method for processing a shape of a sintered body according to an embodiment of the present invention. A method for processing a shape of a sintered body according to an embodiment of the present invention includes the following steps Sa to Sd.

  Step Sa: corresponds to step a. A sintered body having a convex first main surface and a second main surface opposite to the first main surface is prepared.

  Step Sb1: corresponds to the step b1. A first reference surface formed by partially grinding the first main surface of the sintered body, and at least one second reference surface formed by at least partially grinding the second main surface. At least one of them.

  When the second main surface is a concave curved surface, two second reference surfaces (see, for example, two second reference surfaces RSa2 shown in FIG. 2A) are formed by partially grinding the second main surface. To do. When the second main surface is a flat surface, the second reference surface may be formed by grinding the entire second main surface. For example, in the case of a kamaboko-shaped sintered body, the second reference surface becomes the second main surface of the final sintered body and does not need to be ground (processed) thereafter. Hereinafter, the case where the second main surface is a concave curved surface will be mainly described.

  Step Sc: corresponds to step c above. The sintered body is fixed so that the first reference surface or at least one second reference surface contacts the first jig. In other words, the sintered body is fixed with the first main surface facing upward so that at least one second reference surface of the second main surface is in contact with the first jig (see FIG. 3C). Alternatively, the sintered body is fixed with the second main surface facing upward so that the first reference surface of the first main surface is in contact with the first jig (see FIG. 5A).

  Step Sd: corresponds to the above step d. With the sintered body fixed in step Sc, the first main surface is processed into a convex curved surface by grinding the sintered body with the rotating first grinding wheel (see FIG. 3C), or Then, the second main surface is processed into a concave curved surface (see FIG. 5A). When the second main surface is a flat surface, the second main surface may be processed into a flat surface in step Sd. It is preferable to perform process Sd using the processing machine which has a cantilever type grinding part.

  The sintered body prepared in step Sa may be distorted as described above. Therefore, in step Sb1, a reference surface serving as a processing reference is formed on at least one of the first main surface and the second main surface. A first reference surface is formed by partially grinding the first main surface. And / or forming at least one second reference surface by at least partially grinding the second major surface. For example, when the second main surface is a concave curved surface, two second reference surfaces are formed, and when the second main surface is a flat surface, one second reference surface is formed. When the second main surface is distorted, three or more second reference surfaces may be formed.

  Using this first reference surface or at least one second reference surface, the sintered body is fixed to the jig with high accuracy. Since it fixes with a 1st jig | tool using a 1st reference surface or a 2nd reference surface, it can fix with high precision irrespective of the presence or absence and the grade of the distortion | strain of a sintered compact. Moreover, it is not necessary to use an adhesive. What is necessary is just to prepare a 1st jig | tool suitably according to the shape and magnitude | size of a sintered compact. An example of the first jig will be described later with reference to FIG.

  As described with reference to FIG. 2A, in step Sb1, both the first reference surface and at least one second reference surface may be formed. At this time, it is preferable that the first reference surface and the at least one second reference surface are parallel to each other.

  The method for processing a shape of a sintered body according to an embodiment of the present invention further includes a step Sb2 of forming two parallel first side surfaces defining the width W of the sintered body between the step Sa and the step Sd. May be. Moreover, you may further include process Sb3 which forms two mutually parallel 2nd side surfaces which prescribe | regulate the length of a sintered compact between process Sa and process Sd. Steps Sb2 and / or Sb3 may be performed according to the required accuracy. The first side surface formed by the step Sb2 serves as a reference in the width direction when the sintered body is fixed to the second jig in the step Se to be described later, restricts the inclination of the sintered body, and improves the processing accuracy. Have a role. Further, in the retarder and the motor, since the position of the magnet in the circumferential direction affects the performance, it is preferable that the accuracy of the width W is high, and it is preferable to perform the step Sb2. In addition, what is necessary is just to form the predetermined | prescribed inclination side surface in process Sb2, when the side surface which prescribes | regulates a width | variety like the sintered magnet 10c shown in FIG.11 (c). Steps Sb1, Sb2, and / or Sb3 are performed using, for example, a horizontal axis opposed biaxial surface grinder, as will be described later with reference to FIG.

  The shape processing method of the sintered body according to the embodiment of the present invention may include the following steps Se and Sf after the step Sd.

  Step Se: corresponds to the step e. The sintered body is fixed so that at least a part of either the first main surface or the second main surface processed in step Sd is in contact with the second jig.

  Step Sf: corresponds to step f above. In a state where the sintered body is fixed in step Se, the other of the first main surface and the second main surface is processed into a predetermined shape by grinding the sintered body with the rotating second grinding wheel.

  For example, when the first main surface is processed in step Sd, step Sf is a step of processing the second main surface. When the second main surface is a concave curved surface like the sintered magnet 10a, the step Sf is a step of processing the second main surface into a concave curved surface. When the second main surface is processed in step Sd, step Sf is a step of processing the first main surface into a convex curved surface. By performing step Sf, the first main surface and the second main surface that define the thickness of the sintered body are processed into a desired shape.

  When processing in step Sf, the sintered body can be fixed with high accuracy by fixing the surface processed in step Sd and the first side surfaces on both sides to the second jig as reference surfaces. At this time, it is not necessary to use an adhesive. An example of the second jig will be described with reference to FIG. 4, but is not limited to the example of FIG. 4, and may be appropriately prepared according to the shape and size of the sintered body. The second jig may be the same as the first jig.

  Hereinafter, with reference to FIG. 2 to FIG. 8, a specific example of a sintered body shape processing method and an apparatus used therefor according to an embodiment of the present invention will be described. Here, the sintered magnet 10a shown in FIG. 11A is used as the sintered body.

  FIG. 2A is a schematic diagram for explaining a step (step Sb1) of forming the first reference surface and the second reference surface on the sintered magnet 10a, and FIG. 2B is a view showing the sintered magnet 10a. It is a schematic diagram for demonstrating the process (process Sb2) which forms the side surface which prescribes | regulates the width | variety, FIG.2 (c) is the process (process Sb3) which forms the side surface which prescribes | regulates the length of the sintered magnet 10a. It is a schematic diagram for demonstrating.

  Step Sb1 is a step of forming the first reference surface RSa1 and the second reference surface RSa2, for example, as shown in FIG. Since the sintered magnet 10a has an arcuate shape, one first reference surface RSa1 and two second reference surfaces RSa2 are formed. In the case of a semi-cylindrical sintered magnet such as the sintered magnet 10b shown in FIG. 11B, the entire flat second main surface may be used as one second reference surface.

  As shown in FIG. 2A, the process Sb1 is performed using, for example, a biaxial surface grinding machine 20a facing the horizontal axis. The first reference surface RSa1 is formed by partially grinding the first main surface SO of the sintered magnet 10a, and the two second reference surfaces RSa2 are formed by partially grinding the second main surface SI. To do. The first reference surface RSa1 and the two second reference surfaces RSa2 are formed in parallel to each other. Note that it is not always necessary to form both the first reference surface RSa1 and the second reference surface RSa2. When the first main surface SO is processed in the step Sd, only the second reference surface RSa2 is formed in the step Sd. In the case of processing, only the first reference surface RSa1 may be used. When only one of the first reference surface RSa1 and the second reference surface RSa2 is formed, for example, a surface grinding machine can be used.

  The widths of the first reference surface RSa1 and the two second reference surfaces RSa2 are independently set to about 1 mm or more and 5 mm or less. If it is smaller than this, the function as the reference surface will not be sufficiently performed, and if it is larger than this, the material and the grinding time will be wasted. Note that this is not the case when the second main surface SI is flat and the entire second main surface SI is one second reference surface RSa2. In order to form such first reference surface RSa1 and second reference surface RSa2, the sintered magnet 10a is designed to be larger than the net shape in advance.

  Step Sb2 is performed, for example, using a biaxial surface grinder 20b facing the horizontal axis, as shown in FIG. 2B. By grinding a part of the sintered magnet 10a, two parallel first side surfaces RSb1 and RSb2 that define the width W1 of the sintered magnet 10a are formed. The first side surfaces RSb1 and RSb2 serve as a reference in the width direction when the sintered magnet 10a is fixed to the second jig in the step Se, thereby restricting the inclination of the sintered magnet 10a and improving the processing accuracy.

  Step Sb3 is performed, for example, using a biaxial surface grinding machine 20c facing the horizontal axis, as shown in FIG. By grinding a part of the sintered magnet 10a, two parallel second side surfaces RSc1 and RSc2 that define the length L1 of the sintered magnet 10a are formed.

  The horizontal axis opposed biaxial surface grinding machines 20a to 20c may be used by changing only the interval between the grindstones using the same apparatus. The grindstone is, for example, a resin bond grindstone that holds diamond abrasive grains with a resin bond. The rotation speed is, for example, 500 rpm or more and 1500 rpm or less. The feed speed of the sintered magnet 10a is, for example, not less than 0.5 m / min and not more than 3 m / min. The dimensional accuracy of the width W1 and the length L1 obtained at this time is about ± 0.02 mm.

  Hereinafter, a case where the first main surface SO is processed in the step Sd and the second main surface SI is processed in the step Sf will be described.

  FIGS. 3A to 3C are diagrams schematically illustrating a jig 30A for forming a convex curved surface on the sintered magnet 10a and a state in which the sintered magnet 10a is fixed to the jig 30A.

  The shape processing method according to the embodiment of the present invention may include a step of fixing the plurality of sintered magnets 10a to the first jig in a row. For example, a jig 30A shown in FIG. 3A can be suitably used as the first jig. The jig 30A is disposed at one end of the sintered magnet 10a in the length L1 direction, and two side walls 32a and 32b that are in contact with or close to the two first side surfaces RSb1 and RSb2 that define the width W1 of the sintered magnet 10a. And the movable side wall 32d disposed at the other end in the length L direction of the sintered magnet 10a. As shown in FIG. 3B, the plurality of sintered magnets 10a are arranged in contact with each other along the length L1 direction. The plurality of sintered magnets 10a are sandwiched by moving the movable side wall 32d toward the side wall 32c. By turning the screw 34b of the tightening portion 34, the contact plate portion 34a pushes the movable side wall 32d and moves the movable side wall 32d toward the side wall 32c. The movable side wall 32d pushes the plurality of sintered magnets 10a toward the side wall 32c with a small torque of 10 cN · m, for example. In order to suppress variation by the operator, it is preferable to turn the screw 34b using a minute torque wrench. The distance W between the two side walls 32a and 32b that are in contact with or close to the two first side surfaces RSb1 and RSb2 that define the width W1 of the sintered magnet 10a is, for example, a clearance relative to the width W1 of the sintered magnet 10a. Is set to 1.0 μm or more and 50 μm. The distance W is appropriately set according to the dimensional accuracy required for the sintered magnet 10a. The side walls 32a and 32b are fixed to the base plate 30a by screws. One side wall 32a or 32b is loosened, and the other side wall 32b or 32a is fixed, and this is used as a reference (that is, so as to abut on it). After arranging the plurality of sintered magnets 10a, one side wall 32a or 32b may be fixed so as to contact the side surface of the plurality of sintered magnets 10a.

  At this time, as shown in FIG. 3C, the sintered magnet 10a is arranged so that the first main surface SO faces up and the second reference surface RSa2 of the second main surface SI contacts the jig 30A. The sintered magnet 10a is fixed. In this way, the sintered magnet 10a is fixed to the jig 30A without using an adhesive. Of course, one sintered magnet 10a can be fixed using a jig having the same structure as the jig 30A.

  Thereafter, the first main surface SO is processed into a convex curved surface by grinding the first main surface SO side of the sintered magnet 10a with the rotating first grinding wheel. The processing steps will be described later with reference to FIG.

  For example, a jig 30B shown in FIG. 4 can be used for processing the second main surface SI. 4A to 4C are diagrams schematically showing a jig 30B for forming a concave curved surface in the sintered magnet 10a and a state in which the sintered magnet 10a is fixed to the jig 30B. Members having substantially the same function as the jig 30A shown in FIG.

  A jig 30B shown in FIGS. 4A to 4C has basically the same structure as the jig 30A shown in FIGS. 3A to 3C, and in addition, a convex curved surface. It has two rails 33a and 33b that are in contact with the first main surface SO. In the step of grinding the second main surface SI, the sintered magnet 10a has the second main surface SI facing up, and the sintered magnet 10a so that at least a part of the first main surface SO contacts the jig 30B. Can be fixed. The two rails 33a and 33b are preferably arranged symmetrically with respect to the center line of the convex curved surface. The method of arranging and fixing the plurality of sintered magnets 10a on the jig 30B is the same as the case of using the jig 30A.

  The example in which the first main surface SO is processed in the step Sd and the second main surface SI is processed in the step Sf has been described above with reference to FIGS. 3 and 4. In the sintered body shape processing method according to the embodiment of the present invention, the second main surface SI may be processed in step Sd, and the first main surface SO may be processed in step Sf.

  When processing the second main surface SI of the sintered magnet 10a in the step Sd, the first main surface SI of the sintered magnet 10a is directed upward using the jig 30C shown in FIG. This is performed with the sintered magnet 10a fixed so that the first reference surface RSa1 of the main surface SO is in contact with the jig 30C.

  In step Sf, the first main surface SO is fixed in a state where the sintered magnet 10a is fixed so that a part of the second main surface SI processed in step Sd contacts the jig 30D shown in FIG. Is processed into a convex curved surface. If the sintered magnet 10a is processed in this order, it is not necessary to use a jig having rails 33a and 33b like the jig 30B shown in FIG.

  The grinding process will be described with reference to FIGS. FIG. 6 is a schematic diagram showing a processing machine 40A including a cantilever grinding part for forming a convex curved surface on the sintered magnet 10a. FIG. 7 is a schematic diagram showing a processing machine 40B including a cantilever grinding part for forming a concave curved surface in a sintered body. The only difference is that the grinding wheel 52a of the processing machine 40A is for forming a convex curved surface, whereas the grinding wheel 52b of the processing machine 40B is for forming a concave curved surface.

  The processing machine 40A includes a grinding wheel 52a having a curved surface in which the outer peripheral surface of the disk is recessed in the radial direction, a motor 42 having a rotating shaft 44, and a hydraulic bush 46 for fixing the grinding wheel 52a to the rotating shaft 44 of the motor 42. It has a cantilever grinding section and a mechanism section 60 that moves the rotary shaft 44 in the vertical direction.

  The sintered magnet 10a fixed to the jig 30A is disposed on a movable stage (not shown) and is moved back and forth horizontally in a direction perpendicular to the rotation axis. The grinding step includes, for example, a step of grinding the sintered magnet 10a while moving the sintered magnet 10a in the first direction with respect to the grinding wheel 52a at a first speed, and a second direction opposite to the direction of 1 with respect to the grinding wheel 52a. Moving in a direction at a second speed greater than the first speed. The first speed is, for example, 200 mm / min or more and 500 mm / min or less, and the second speed is, for example, 1000 mm / min or more and 3000 mm / min or less. In the step of grinding while moving in the first direction at the first speed, all or most of the grinding step is completed, but the step of moving in the second direction at a second speed greater than the first speed In this case, less grinding than the grinding step in the first direction may be performed.

  The rotating shaft 44 preferably has a rigidity equal to or higher than, for example, 240 N / μm (the magnitude of the secondary moment necessary for generating a deflection of 1 μm). The rigidity of the rotating shaft 94 of the double-sided processing machine 90 shown in FIG. 10 is about 10 N / μm, and the rotating shaft 44 of the processing machine 40A has a rigidity of 20 times or more. By using the rotating shaft 44 having high rigidity in this way, high processing accuracy can be obtained even in the cantilever type.

  The grinding wheel 52a is obtained by electrodepositing only one layer of diamond abrasive grains (particle size: 100 μm to 200 μm). In order to obtain high processing accuracy, it is necessary to replace them as appropriate. In addition, since the sintered magnets processed here are a small variety of products, the frequency of exchanging the grinding wheel 52a is high depending on the size and shape. Electrodeposition grindstones are suitable for high-change processing with a small variety and a high variety.

  Here, the grinding wheel 52 a is fixed to the rotating shaft 44 using the hydraulic bush 46. As the hydraulic bush 46, a friction joint described in JP-T-2009-509099 (International Publication No. 2007/032730) can be used. For example, ETP-T-50 manufactured and sold by ETP can be used as the ETP bush.

  Please refer to FIG. 8A to 8C are schematic views showing the hydraulic bush 46. FIG. 8A is a sectional view, FIG. 8B is a side view, and FIG. It is sectional drawing which shows the mode when it did.

  The hydraulic bush 46 has a flange 46f and a sleeve 46s. By tightening the pressure screw 48, the pressure medium 46m filled in the chamber of the sleeve 46s is pressurized. The sleeve 46s receives the pressure from the pressure medium 46m from the inside, and fastens the rotating shaft 44 and the hub 52h of the grinding wheel as shown in FIG. 8C. The hydraulic bush 46 is fixed to the rotating shaft 44 by a set screw 47.

  The hydraulic bush 46 has high concentricity and can be easily removed, and the processing machines 40A and 40B have extremely high workability compared to the processing machine 90 shown in FIG. Since the hydraulic bush 46 and the rotating shaft 44 are straight-fitting, the rotating shaft 44 is not easily worn down, and dust biting, eccentricity, and the like are unlikely to occur. For this reason, the grindstone lasts for a long time, and correction grinding of the rotating shaft, which was necessary in the case of taper fitting, is also unnecessary. Moreover, since it is hydraulic, the rotating shaft 44 can be held with sufficient force, and the rigidity of the rotating shaft 44 can be increased. For this reason, high processing accuracy can be maintained even in a cantilever type. Further, since the rotating shaft 44 is supported and the end portion is protected by the shielding plate 72 for limiting the range in which the grinding fluid is scattered, maintenance is also easy.

  Using the processing machines 40A and 40B, the sintered magnet 10a having T1 = about 10 mm, W1 = about 50 mm, and L1 = about 60 mm was processed and the processing accuracy was evaluated. As a result, the first main surface (convex curved surface) SO With 9 points (100 samples), the variation (difference between the maximum value and the minimum value) was 0.038 mm, and σ was 0.009, and very high processing accuracy was obtained.

  The embodiment of the present invention is suitably used for a shape processing method and a processing apparatus of a sintered body, particularly for shape processing of a rare earth sintered magnet.

DESCRIPTION OF SYMBOLS 10 Sintered body 10a, 10b, 10c Sintered magnet 20a, 20b Horizontal axis opposing biaxial surface grinding machine 30A, 30B Jig 40A, 40B Processing machine 42 Motor 44 Rotating shaft 46 Hydraulic bush 46f Flange 46m Pressure medium 46s Sleeve 47 Stop Screw 48 Pressure screw 52a, 52b Grinding wheel 52h Hub 60 Mechanism part 72 Shield plate 80a, 80b Movable stage 82 Base plate

Claims (13)

Preparing a sintered body having a convex first main surface and a second main surface opposite to the first main surface;
A first reference surface formed by partially grinding the first main surface of the sintered body and at least one second reference formed by at least partially grinding the second main surface. A step b1 of forming at least one of the surfaces;
Fixing the sintered body such that the first reference surface or the at least one second reference surface is in contact with a first jig; and
In a state where the sintered body is fixed in the step c, the first main surface is processed into a convex curved surface by grinding the sintered body with a rotating first grinding wheel, or the second main surface A method of processing a shape of a sintered body, comprising a step d of processing a surface into a concave curved surface or a flat surface.   The method for processing a shape of a sintered body according to claim 1, wherein the step b1 includes a step of forming both the first reference surface and the at least one second reference surface.   The step d comprises a step of grinding the sintered body while moving the sintered body at a first speed in a first direction with respect to the first grinding wheel, and the first direction with respect to the first grinding wheel. The shape processing method of the sintered compact of Claim 1 or 2 including the process of moving to the 2nd direction opposite to this at the 2nd speed | rate larger than the said 1st speed | rate.   The said process c is a shape processing method of the sintered compact in any one of Claim 1 to 3 including the process of fixing the said several sintered compact to the said 1st jig | tool in a line. After the step d, a step of fixing the sintered body so that at least a part of either the first main surface or the second main surface processed in the step d is in contact with the second jig. e,
With the sintered body fixed in the step e, the sintered body is ground by a rotating second grinding wheel to process the other of the first main surface or the second main surface into a predetermined shape. The method of processing a shape of a sintered body according to any one of claims 1 to 4, further comprising a step (f).   The step f comprises grinding the sintered body while moving the sintered body in a third direction at a third speed with respect to the second grinding wheel, and the third direction with respect to the second grinding wheel. The method of shape processing of a sintered body according to claim 5, further comprising a step of moving in a fourth direction opposite to the first direction at a fourth speed larger than the third speed.   The said process e is a shape processing method of the sintered compact of Claim 5 or 6 including the process of fixing the said some sintered compact to the said 2nd jig in a line.   The shape processing method for a sintered body according to any one of claims 1 to 7, wherein the first main surface is processed into a convex curved surface in the step d.   The sintering according to any one of claims 1 to 7, wherein the second main surface is processed into a concave curved surface or a flat surface in the step d, and the first main surface is processed into a convex curved surface in the step f. Body shape processing method.   10. The method according to claim 1, further comprising a step b <b> 2 of forming two first side surfaces parallel to each other that define a width of the sintered body between the step a and the step d. 11. Shape processing method of sintered body.   11. The method according to claim 1, further comprising a step b <b> 3 of forming two parallel second side surfaces defining the length of the sintered body between the step a and the step d. The shape processing method of the sintered compact. It is a processing apparatus used for the shape processing method of the sintered compact according to any one of claims 1 to 11,
Cantilever grinding comprising: a grinding wheel whose outer peripheral surface of the disk is a concave curved surface or a convex curved surface with respect to the radial direction; a motor having a rotating shaft; And
A processing apparatus comprising: a mechanism member that moves the rotating shaft in a vertical direction.   The processing apparatus according to claim 12, wherein the rotation shaft has a rigidity of 240 N / μm or more.

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