Grinding device and method for manufacturing rare earth sintered magnet

Abstract

To improve dimensional accuracy of grinding by increasing the positioning accuracy of a workpiece during grinding.SOLUTION: A grinding apparatus includes: a grinding wheel supported so as to be rotatable about a central axis; and a support table having a sliding surface for slidably supporting a workpiece, the support table being disposed so as to sandwich the workpiece between the sliding surface and an outer peripheral surface of the grinding wheel. The outer peripheral surface of the grinding wheel has an arch-shaped curve in a cross section taken along a plane including the central axis. The support table has a plurality of slits formed in the sliding surface and two guides extending in parallel on both sides of the workpiece positioned on the sliding surface, and the plurality of slits are inclined with respect to a direction in which the guides extend.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present application relates to a grinding device and a method for producing a rare earth sintered magnet. [Background technology]

[0002] Various continuous processing methods have been proposed for processing rare earth sintered magnets into a tile-shaped shape (Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-347900 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-234496 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-178246 Summary of the Invention [Problem to be solved by the invention]

[0004] In these continuous processing methods, processing waste tends to accumulate on the table (transport table) that transports the rare earth sintered magnet workpieces (workpieces). If processing waste is present on the transport table, it may become trapped between the workpiece and the transport table and cause the workpiece to change position and orientation, reducing processing accuracy.

[0005] Furthermore, if the width of the conveying table (the distance between the guides on both sides of the conveying path) is set to be approximately the same as the width of the workpiece, the workpiece may hit the guides on the conveying table, preventing it from being transported properly. Therefore, the width of the conveying table must be larger than the width of the workpiece. However, if the width of the conveying table is larger than the width of the workpiece, the position of the workpiece may move in the width direction of the conveying table while being transported, which is inconvenient as it causes the position and orientation of the workpiece in the width direction relative to the grinding wheel to easily change.

[0006] The embodiments of the present invention provide a grinding device and a method for producing a rare earth sintered magnet that can solve these problems. [Means for solving the problem]

[0007] In an exemplary, non-limiting embodiment, the grinding apparatus of the present disclosure includes a grinding wheel rotatably supported about a central axis, and a support table having a sliding surface for slidably supporting a workpiece, the support table being arranged so as to sandwich the workpiece between the sliding surface and the outer peripheral surface of the grinding wheel. The outer peripheral surface of the grinding wheel has an arch-shaped curve in a cross section taken along a plane including the central axis. The support table has multiple slits formed in the sliding surface and two guides extending parallel to each other on both sides of the workpiece positioned on the sliding surface, the multiple slits being inclined with respect to the extension direction of the guides.

[0008] In one embodiment, the inclination angle of each slit relative to the extending direction of the guide is equal to or greater than 10 degrees and equal to or less than 80 degrees.

[0009] In one embodiment, the center-to-center distance of the plurality of slits is 2 mm or more and 50 mm or less, and the width of each slit is 1 mm or more and 10 mm or less.

[0010] In one embodiment, the distance between the two guides is wider than the width of the workpiece, and when the outer surface of the grinding wheel is grinding the top surface of the workpiece, one of the two guides contacts one end of the workpiece in the width direction.

[0011] In one embodiment, the difference between the distance between the two guides and the width of the workpiece is 200 μm or more and 1 mm or less.

[0012] In one embodiment, the shape of the curve in the cross section is symmetrical with respect to a reference plane perpendicular to the central axis, and the distance from the guide that contacts one end of the workpiece to the reference plane is shorter than the distance from the other guide that does not contact the workpiece to the reference plane.

[0013] In one embodiment, each of the plurality of slits extends from one of the two guides to the other.

[0014] In one embodiment, the two guides are fixed to the sliding surface of the support table so as to intersect with the plurality of slits.

[0015] In one embodiment, the apparatus includes a pair of rollers that transmit force to the workpiece so that the workpiece moves along the sliding surface of the support table, and a conveying device that supplies the workpiece to a position where it is sandwiched between the pair of rollers.

[0016] In an exemplary embodiment, the method for manufacturing a rare earth sintered magnet of the present disclosure includes the steps of preparing a workpiece of a rare earth sintered magnet, and processing the workpiece using any of the grinding devices described above, thereby forming a processed shape on the upper surface of the workpiece using the outer circumferential surface of the grinding wheel. [Effects of the Invention]

[0017] According to embodiments of the present invention, it is possible to provide a grinding device and a method for manufacturing a rare earth sintered magnet, in which processing debris is less likely to accumulate on the conveying table, and the position of the workpiece in the width direction during grinding is regulated, thereby realizing an appropriate position and orientation of the workpiece relative to the grinding wheel. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating a configuration example of a grinding device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a top view schematically showing a support table in the present embodiment. [Figure 4] FIG. 2 is a perspective view schematically showing a support table in the present embodiment. [Figure 5] FIG. 2 is a schematic cross-sectional view showing the center-to-center distance P and width D of slits in the support table. [Figure 6] FIG. 1 is a perspective view of a support table with a guide attached thereto. [Figure 7] FIG. 10 is a top view schematically showing the movement of a workpiece moving on a support table. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described. However, more detailed descriptions than necessary may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the inventors provide the accompanying drawings and the following description to enable those skilled in the art to fully understand the present disclosure, and do not intend them to limit the subject matter described in the claims. In the following description, components having the same or similar functions are designated by the same reference numerals.

[0020] The following embodiments are examples, and the technology of the present disclosure is not limited to the following embodiments. For example, the numerical values, shapes, materials, steps, step order, display screen layout, etc. shown in the following embodiments are merely examples, and various modifications are possible as long as no technical contradiction occurs. Furthermore, one aspect can be combined with another aspect as long as no technical contradiction occurs.

[0021] First, a configuration example of a grinding device according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing a configuration example of a grinding device according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. For reference, the figure shows orthogonal X-, Y-, and Z-axes.

[0022] The grinding apparatus 100 in this embodiment includes a grinding wheel 10, a support table 30, and a conveying table 40. The grinding wheel 10 is supported rotatably about a central axis C. In this example, the central axis C is parallel to the X-axis. The grinding wheel 10 generally has a disk or cylindrical shape and is symmetrical about the central axis C. As shown in FIG. 2, the outer peripheral surface 10S of the grinding wheel 10 has an arch-shaped curve in a cross section cut along a plane including the central axis C. In this example, the arch-shaped curve has a convex shape toward the central axis C.

[0023] High-hardness abrasive grains, such as diamond, are adhered to the outer peripheral surface 10S of the grinding wheel 10. The outer peripheral surface 10S of the grinding wheel 10 comes into contact with the upper surface of the workpiece 20 and grinds the upper surface of the workpiece 20. This type of grinding is sometimes called "shape machining." After grinding, the upper surface of the workpiece 20 has a cross-sectional shape determined by the curved shape of the outer peripheral surface 10S of the grinding wheel 10. In this embodiment, the workpiece 20 has an upwardly convex semi-cylindrical shape. The size, shape, and material of the workpiece 20 are not particularly limited.

[0024] The grinding wheel 10 is driven by, for example, an electric motor. In FIG. 1, the grinding wheel 10 rotates counterclockwise. When the workpiece 20 is a rare earth sintered magnet, the rotation speed is, for example, 1,000 to 5,000 rpm. The diameter of the grinding wheel 10 is, for example, in the range of 100 to 300 mm. The speed (peripheral speed) at which the outer circumferential surface 10S of the grinding wheel 10 moves in the negative direction of the Z axis relative to the top surface of the workpiece 20 can be, for example, 1,500 to 2,000 m / min. These numerical values ​​are merely examples and can be changed as appropriate depending on the size, dimensions, material, etc. of the workpiece 20.

[0025] The support table 30 has a sliding surface 30S that slidably supports the workpiece 20. The support table 30 is disposed so as to sandwich the workpiece 20 between the sliding surface 30S and the outer peripheral surface 10S of the grinding wheel 10. A detailed configuration example of the support table 30 will be described later.

[0026] In this embodiment, the apparatus includes a pair of rollers 50A, 50B that transmit force to the workpiece 20 so that the workpiece 20 moves along the sliding surface 30S of the support table 30, and a conveying device that supplies the workpiece 20 to a position sandwiched between the pair of rollers 50A, 50B. The pair of rollers 50A, 50B may be formed from an elastic material such as urethane. The pair of rollers 50A, 50B are positioned so as to sandwich the workpiece 20 from above and below while rotating. An example of the conveying device is a belt conveyor that carries and moves the workpiece 20. The workpiece 20 moving on the belt conveyor is pushed in the positive direction of the Z axis by the rotating pair of rollers 50A, 50B toward the processing position of the grinding wheel 10. The workpiece 20 being processed by the grinding wheel 10 comes into contact with the next workpiece 20 to be processed and receives the force (in the positive direction of the Z axis) from the rollers 50A, 50B via the workpieces 20 lined up in a row before grinding.

[0027] Next, a configuration example and function of the support table 30 will be described with reference to Fig. 3 to Fig. 7. First, Fig. 3 and Fig. 4 will be referred to. Fig. 3 is a top view schematically showing the support table 30 in this embodiment. Fig. 4 is a perspective view schematically showing the support table 30 in this embodiment.

[0028] As shown in these figures, the support table 30 has multiple slits 32 formed in the sliding surface 30S. The slits 32 only need to be sized to allow machining waste to be discharged downward. If the upper surface of the support table 30 is formed, for example, from a metal plate, the slits 32 are openings that penetrate the metal plate from the top to the bottom. The machining waste passes through these openings and is removed from the sliding surface 30S. This prevents machining waste from getting between the sliding surface 30S and the workpiece 20, making it possible to improve the dimensional accuracy of the grinding process.

[0029] 5 is a schematic cross-sectional view showing the center-to-center distance P and width D of the slits in the support table 30. In this embodiment, the center-to-center distance P of the multiple slits 32 is 2 mm or more and 50 mm or less. The width D of each slit 32 is 1 mm or more and 10 mm or less.

[0030] The sliding surface 30S of the support table 30 is on the same plane except for the slits 32, and is flat and smooth overall. The workpiece 20 is ground by the grinding wheel 10 while moving on the sliding surface 30S of the support table 30. Therefore, the support table 30 functions as a "feed table" or "lower surface reference jig" for the grinding process. The support table 30 may have an upper surface plate in which multiple slits 30S are formed, and a support member that supports the upper surface plate. The configuration of the support table 30 other than the sliding surface 30S in which the slits 32 are formed is optional. A container may be placed below to collect cutting waste that falls through the slits 32S.

[0031] Next, reference is made to Figures 6 and 7. Figure 6 is a perspective view of a support table to which a pair of guides are attached. Figure 7 is a top view schematically showing the movement of workpiece 20 moving on support table 30.

[0032] As shown in FIGS. 6 and 7, the support table 30 has two guides 34A and 34B extending parallel to the Z-axis direction on both sides of the workpiece 20 moving on the sliding surface 30S. The multiple slits 32 are inclined with respect to the direction in which the guides 34A and 34B extend (the Z-axis direction). In this embodiment, the inclination angle θ of each slit 32 with respect to the direction in which the guides 34A and 34B extend is 10 degrees or more and 80 degrees or less. The lower limit of the inclination angle θ is, for example, 20 degrees or more, or 30 degrees or more. The upper limit of the inclination angle θ is, for example, 70 degrees or less, or 60 degrees or less. In the example shown, the inclination angle θ is 45 degrees.

[0033] In this embodiment, the multiple slits 32 each extend from one of the two guides 34A, 34B to the other. More specifically, the two guides 34A, 34B are fixed to the sliding surface 30S of the support table 30 so as to intersect with the multiple slits 32. This fixing can be performed using screws (not shown). When using screws, the fixing positions of the two guides 34A, 34B can be easily changed depending on the width of the workpiece 20 to be machined.

[0034] According to experiments conducted by the inventors, it has been found that when the workpiece 20 is machined by the grinding wheel 10, a force is generated that moves the workpiece 20 in the X-axis direction because the sliding surface 30S of the support table 30 has multiple slits 32 extending diagonally. In the example shown in the figure, a force is applied that moves the workpiece 20 in the positive direction of the X-axis. This force is generated when the workpiece 20 is sandwiched between the grinding wheel 10 and the support table 30 and is pressed by the grinding wheel 10, etc.

[0035] In this embodiment, the distance between the two guides 34A, 34B is wider than the width W of the workpiece 20. As described above, when the workpiece 20 is ground with the grinding wheel 10, the workpiece 20 is subjected to the above-described force and moves in the positive direction of the X-axis. As a result of this force acting in one direction, one of the two guides 34A, 34B (guide 34A in the illustrated example) comes into contact with one end of the workpiece 20 in the width direction. As a result, the position and orientation of the workpiece 20 in the width direction during grinding are regulated by one of the two guides 34A, 34B (guide 34A in the illustrated example).

[0036] In this embodiment, the difference between the distance between the two guides 34A, 34B and the width W of the workpiece 20 is 200 μm or more and 1 mm or less. The difference between the distance between the two guides 34A, 34B and the width W of the workpiece 20 defines the size of the gap between the guides 34A, 34B and the workpiece 20. If the total of the gaps formed on both sides of the workpiece 20 is within the above numerical range, the workpiece 20 can move smoothly through the area sandwiched between the two guides 34A, 34B.

[0037] If the slits 32 in the support table 30 were not present, the position (X coordinate) of the workpiece 20 in the width direction (X axis direction) would vary within a range of 200 μm to 1 mm. Even this level of variation reduces dimensional accuracy and may not be acceptable depending on the application of the workpiece 20. According to this embodiment, when the grinding wheel 10 presses the workpiece 20, there is no gap between the guide 34A and the workpiece 20, and the position (X coordinate) of the workpiece 20 in the width direction (X axis direction) falls within an extremely small range with good reproducibility.

[0038] In this embodiment, as shown in Fig. 2, the curved shape of the outer peripheral surface 10S of the grinding wheel 10 in a cross section cut along a plane including the central axis C is symmetrical with respect to a reference plane Ref that is perpendicular to the central axis C. In the example shown in Fig. 7, during grinding, the guide 34A comes into contact with one end of the workpiece 20. The distance from the guide 34A that comes into contact with the workpiece 20 to the reference plane Ref is set to achieve a desired design value, and is shorter than the distance from the other guide 34B that does not come into contact with the workpiece 20 to the reference plane Ref.

[0039] As is clear from the above description, with the grinding device 100 of this embodiment, the diagonal slits 32 function to prevent the accumulation of processing waste. Furthermore, due to the force that the workpiece 20 receives from the diagonal slits 32 during grinding, the position of the workpiece 20 in the width direction during processing is restricted by one of the guides, realizing an appropriate position and orientation of the workpiece 20 relative to the grinding wheel. This improves the processing accuracy of the workpiece 20, making it possible to obtain a processed product with the desired curved surface shape.

[0040] The grinding device 100 of this embodiment can be suitably used for shaping rare earth sintered magnets.

[0041] The method for manufacturing a rare earth sintered magnet in an embodiment of the present disclosure includes the steps of preparing a workpiece 20 of a rare earth sintered magnet, and processing the workpiece 20 using a grinding device 100 to form a processed shape on the upper surface of the workpiece 20 using the outer surface 10S of the grinding wheel 10.

[0042] According to this embodiment of the method for manufacturing a rare earth sintered magnet, it is possible to improve the dimensional accuracy of the kamaboko-shaped rare earth sintered magnet. Such a rare earth sintered magnet can be suitably used, for example, as a permanent magnet for the rotor of an electric motor. [Explanation of symbols]

[0043] 10. Grinding wheel 10S...outer surface 20 Work 30 Support table 30S...Sliding surface 34A, 34B Guide 40. Transport table 50A, 50B... Feed roller 100 Grinding equipment

Claims

1. a grinding wheel rotatably supported around a central axis; a support table having a sliding surface that slidably supports a workpiece, the support table being arranged so as to sandwich the workpiece between the sliding surface and an outer peripheral surface of the grinding wheel; Equipped with the outer peripheral surface of the grinding wheel has an arch-shaped curve in a cross section cut along a plane including the central axis, The support table is a plurality of slits formed on the sliding surface; and two guides extending parallel to each other on both sides of the workpiece positioned on the sliding surface, The grinding device, wherein the plurality of slits are inclined with respect to a direction in which the guide extends.

2. The grinding device according to claim 1 , wherein an inclination angle of each slit relative to the extending direction of the guide is equal to or greater than 10 degrees and equal to or less than 80 degrees.

3. 3. The grinding device according to claim 1, wherein the center-to-center distance of the plurality of slits is 2 mm or more and 50 mm or less, and the width of each slit is 1 mm or more and 10 mm or less.

4. The distance between the two guides is wider than the width of the workpiece, 4. The grinding device according to claim 1, wherein one of the two guides contacts one end of the workpiece in the width direction when the outer peripheral surface of the grinding wheel is grinding the top surface of the workpiece.

5. 5. The grinding device according to claim 4, wherein the difference between the distance between the two guides and the width of the workpiece is 200 [mu]m or more and 1 mm or less.

6. the shape of the curve in the cross section is symmetrical with respect to a reference plane perpendicular to the central axis, The distance from the guide that contacts the one end of the workpiece to the reference plane is 6. The grinding apparatus according to claim 4, wherein the distance between the other guide that does not contact the workpiece and the reference plane is shorter than the distance between the other guide that does not contact the workpiece and the reference plane.

7. The grinding device according to claim 1 , wherein each of the plurality of slits extends from one of the two guides to the other.

8. 8. The grinding device according to claim 7, wherein the two guides are fixed to the sliding surface of the support table so as to intersect with the plurality of slits.

9. a pair of rollers that transmit force to the workpiece so that the workpiece moves along the sliding surface of the support table; a conveying device that supplies the workpiece to a position sandwiched between the pair of rollers; The grinding device according to claim 1 , comprising:

10. preparing a workpiece of a rare earth sintered magnet; a step of machining the workpiece using the grinding device according to any one of claims 1 to 9, thereby forming a machined shape on the upper surface of the workpiece by the outer circumferential surface of the grinding wheel; A method for producing a rare earth sintered magnet, comprising:

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