JP2007144597A - Electrodeposition grindstone and grinding method using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrodeposition grindstone capable of precluding preventing clogging caused by heat emission or polishing waste generated at the time of grinding. <P>SOLUTION: The electrodeposition grindstone 1 to conduct the contour processing of a work 10 to be processed is structured so that abrasive grains are electrodeposited on the outside surface of a disc-shaped base 2 to form an electrodeposition surface 3. There a grinding liquid supply hole 4 is formed to penetrate the electrodeposition surface 3 from the side face of the base 2 in such an arrangement that one of the openings 4b of the hole 4 faces the outside at the electrodeposition surface 3. At the time of processing the contour, a grinding liquid is poured in from the side face of the base 2 of the grindstone 1 is fed to the surface 3 through the hole 4. At the same time, the liquid is fed to the grindstone 1 also from the grindstone outlet side of the work 10 to be processed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrodeposition grindstone used for contour processing of, for example, a rare earth sintered magnet, and further relates to a grinding method using an electrodeposition grindstone.

  With the demand for miniaturization of various electric parts such as motors and the demand for improvement in the characteristics of magnets corresponding to the demand, development of high-performance small magnets is required. In such a situation, for example, an R-T-B system such as an Nd-Fe-B magnet (R is one or more rare earth elements. T is essential for Fe and contains other metal elements). Magnets have advantages such as excellent magnetic properties, Nd, which is a main component, and abundant resources, and are relatively inexpensive. Therefore, demand for magnets has been increasing in recent years.

  As a method for producing a rare earth sintered magnet, powder metallurgy is known and widely used because it can be produced at low cost. In the method of manufacturing a rare earth sintered magnet by the powder metallurgy method, first, a raw material alloy ingot is first roughly pulverized and finely pulverized to obtain a raw material alloy powder having a particle size of about several μm. The raw material alloy powder thus obtained is oriented in a magnetic field and molded. After molding in a magnetic field, the compact is sintered in a vacuum or in an inert gas atmosphere.

  In the production of the rare earth sintered magnet by the above-mentioned powder metallurgy method, machining for making the obtained rare earth sintered magnet into a predetermined shape is required. Specifically, in the case of rare earth sintered magnets manufactured by powder metallurgy, the compact is greatly shrunk in the sintering process, so contouring and cutting are not possible for products that require high dimensional accuracy. I need it. In the case of a small magnet, a technique of cutting out a magnet piece having a predetermined thickness from a block subjected to contour processing by cutting is also employed.

  By the way, when contour processing is performed on a rare earth sintered magnet, an electrodeposition grindstone in which abrasive grains are electrodeposited on a base metal is used. In particular, abrasive grains are electrodeposited on the outer peripheral surface of a disk-shaped base metal. Electrodeposited whetstones are widely used. For example, the electrodeposition grindstone is obtained by immersing the disc-shaped base metal in an electroplating bath, filling the working surface (the outer peripheral surface) with diamond superabrasive grains, and plating the working surface for one layer of abrasive grains. After temporarily fixing, it is produced by further fixing superabrasive grains by electroplating or electroless plating.

  In the contour processing of the rare earth sintered magnet, a disc-shaped electrodeposition grindstone having an electrodeposited surface shape corresponding to the contour shape is used, and is ground by rotating at a high speed of approximately 3000 rpm or more. To the shape of At this time, the grinding fluid of the electrodeposition grindstone rotating at high speed is supplied with a grinding liquid from one direction or two front and rear directions, and at the same time, the rare earth sintered magnet and the electrodeposition grindstone that are workpieces are prevented from being heated at high temperatures, Polishing waste generated by grinding is quickly discharged.

  In the electrodeposited grindstone, when polishing debris generated by grinding adheres to the gap between the abrasive grains on the electrodeposited surface, which is the working surface of the grindstone, there is a problem that so-called clogging occurs and the grinding force is greatly reduced. In addition, if the superabrasive grains that are fixed wear and fall off, the life of the electrodeposited grindstone will be exhausted. This phenomenon remarkably appears when the grinding volume of the workpiece is large or during heavy grinding such as grinding a hard material such as a rare earth sintered magnet.

  Therefore, for the purpose of eliminating these phenomena, it is essential to supply the grinding fluid as described above, but this is not always sufficient. This is because the conventional electrodeposited grinding stone has a small function (chip dischargeability) for discharging chips generated during grinding from the grinding part with the rotational movement of the grinding wheel, and the grinding fluid is supplied to the grinding part. This is because the cooling effect and the lubrication effect by the grinding liquid are difficult.

From such a situation, for example, Patent Document 1 attempts to solve the above problem by devising the structure of the grindstone. Specifically, in an electrodeposited grindstone composed of a base metal, abrasive grains, and an electrodeposited metal layer that solidifies the abrasive grains on the base metal, the abrasive grains in a predetermined pattern are formed on the outermost surface of the grindstone having a grinding action. An electrodeposition grindstone is disclosed, which is formed by forming an electrodeposition layer composed of an electrodeposition region group having a dent and a hollow region group having no abrasive grains. In the electrodeposition grindstone described in Patent Document 1, as described above, the electrodeposition grindstone region (electrodeposition region group) and the region not having the grindstone (dent region group) are formed on the outermost periphery of the grindstone. It is said that a cooling effect can be obtained by supplying the grinding liquid to the area where the operation is not performed.
JP-A-9-193022

  However, even if the grindstone is devised as in the invention described in Patent Document 1, the amount of the grinding liquid supplied to the region not having the grindstone is small, and particularly in heavy grinding, the cooling ability is insufficient. When grinding a workpiece having a high grinding resistance such as a sintered magnet, that alone is not sufficient. Further, in the technique described in Patent Document 1, when contour processing (processing with a general-purpose grindstone) is performed, a pattern applied to the outer periphery of the grindstone may become complicated.

  For example, when a square block is contoured in an arc shape, there is a portion with a large grinding volume (grinding allowance) on the electrodeposition surface of the grindstone. When contour processing is performed in an arc shape with a depressed center, the central portion of the electrodeposition surface is a portion with a large grinding allowance. Such a portion with a large grinding allowance is liable to cause uneven wear, resulting in a decrease in processing accuracy, an advance in the life and replacement time of the grindstone, and a tendency to increase the occurrence of cracks and chips during processing. Unlike the surface grinding, such a problem is a problem peculiar to the electrodeposition grindstone used for the contour processing, and cannot be solved by the technique described in Patent Document 1.

  The present invention has been proposed in view of such a conventional situation, and an object of the present invention is to prevent heat generated during grinding and prevent clogging due to polishing residue in an electrodeposited grinding wheel that performs contour machining. Thus, an object of the present invention is to provide an electrodeposition grindstone in which the abrasive grains on the electrodeposited surface are less likely to wear and drop off. Furthermore, an object of the present invention is to provide a grinding method capable of stabilizing machining dimensions and the number of productions, further reducing costs and simplifying maintenance by using an electrodeposition grindstone. .

  In order to achieve the above-mentioned object, the electrodeposition grindstone of the present invention is an electrodeposition electrode for performing contour processing of a workpiece by forming an electrodeposition surface by electrodepositing abrasive grains on the outer peripheral surface of a disk-shaped base metal. A grinding fluid supply hole that penetrates from the side surface of the disk-shaped base metal to the electrodeposition surface is formed so that one opening of the grinding fluid supply hole faces the outside on the electrodeposition surface. It is formed in the form to do. Further, the grinding method of the present invention uses the electrodeposition grindstone, injects a grinding liquid from the side surface of the disk-shaped base metal of the electrodeposition grindstone, and grinds the electrodeposited surface through the grinding liquid supply hole. It is characterized in that contour processing of a workpiece is performed while supplying a liquid.

  In the electrodeposition grindstone of the present invention, as described above, the grinding fluid supply hole extending from the side surface of the disk-shaped base metal to the electrodeposition surface is formed so as to penetrate, and one opening of the grinding fluid supply hole is formed outside on the electrodeposition surface. It is formed so as to face and open. Therefore, the grinding liquid is directly supplied to the grinding portion of the grindstone, so that effective cooling and smooth discharge of polishing residue are realized.

  As a technique for supplying a grinding fluid to a grinding surface of a grindstone, for example, a technique disclosed in Japanese Patent Publication No. 58-2034 is also known. However, the invention described in the above gazette describes a grindstone-containing network metal structure. The grinding liquid is supplied from the back side and guided to the abrasive surface, and the opening of the grinding liquid supply hole is not directly formed on the electrodeposition surface as in the present invention. In the present invention, it is important to supply the grinding liquid directly to the electrodeposition surface (abrasive surface), thereby realizing the effective cooling and the smooth discharge of polishing residue. When the grinding liquid is supplied from the back side of the grindstone-containing reticulated metal structure as in the invention described in the publication, it is considered that a cooling effect can be obtained to some extent, but it is difficult to efficiently discharge the polishing residue.

  For example, when grinding a hard metal such as a rare earth sintered magnet, a sticky polishing residue adheres to the abrasive surface. However, as in the invention described in Japanese Patent Publication No. 58-2034, the abrasive surface is ground on the abrasive surface. When the containing net-like metal structure is formed, the polishing residue enters therein, and cannot be discharged by supplying the grinding liquid from the back surface. Therefore, it is difficult to apply to heavy grinding applications, and it is described in the above publication that it is suitable for the purpose of lapping.

  In the present invention, since grinding is performed on the electrodeposited surface on which the abrasive grains are electrodeposited without forming such a grindstone-containing network metal structure, heavy grinding processing such as contour processing is possible, and the polishing residue is reduced. Never get into the mesh. Then, the polishing residue adhering to the electrodeposition surface is quickly washed away by the grinding liquid sprayed directly onto the electrodeposition surface.

  According to the electrodeposition grindstone of the present invention, it is possible to prevent heat generated during grinding and to prevent clogging due to polishing residue, reducing grinding resistance, extending the service life, reducing costs, and simplifying maintenance. Such effects can be obtained.

  In addition, according to the grinding method of the present invention, the function of the electrodeposition grindstone can provide effects such as a constant processing speed, a stable workpiece size, and a stable production number. It is also possible to achieve a reduction in process and process maintenance.

  Hereinafter, an electrodeposition grindstone and a grinding method to which the present invention is applied will be described in detail with reference to the drawings.

  The electrodeposition grindstone 1 of the present invention performs, for example, a grinding process (so-called contour machining) in which a rare earth sintered magnet is machined into a predetermined shape. As shown in FIGS. The electrodeposition surface 3 which becomes a grinding part is formed on the outer peripheral surface of the substrate. The disc-shaped base metal 2 is thickened at the center portion to form a mounting portion 2a, and a grindstone mounting hole 2b is formed here. Therefore, the electrodeposition grindstone 1 is mounted on a grinding apparatus by inserting and fixing a rotating shaft in the grindstone mounting hole 2b, and is rotated at a high speed by the rotating shaft, and the electrodeposited surface 3 that is the outer peripheral surface is processed. Grinding (contouring) is performed by contacting the object. Further, the outer peripheral side portion of the disc-shaped base metal 2 is a grindstone base metal part 2c having a thickness corresponding to the width of the workpiece to be ground, and an electrodeposition surface at the tip (outermost peripheral surface). 3 is formed.

  The electrodeposition surface 3 is configured by electrodepositing and fixing abrasive grains on the outer peripheral surface of the disk-shaped base metal 2, and examples of the abrasive grains include superabrasives such as diamond and boron nitride cubic (CBN). Grain is used. These abrasive grains are fixed to the electrodeposition surface 3 by an electrodeposition metal such as Ni.

  The shape of the electrodeposition surface 3 has a shape corresponding to the contour shape of the workpiece, and in the case of this embodiment, the electrodeposition surface 3 has a shape protruding in a circular arc shape corresponding to the workpiece surface shape of the workpiece. FIG. 3 shows a contour machining shape of the workpiece 10 by the electrodeposition grindstone 1. In the case of this example, the upper surface of the square block-shaped workpiece (for example, rare earth sintered magnet) 10 shown in FIG. 3A is ground to an arc surface 10a as shown in FIG. Therefore, the electrodeposition surface 3 of the electrodeposition grindstone 1 has a convex portion 3a having an arcuate cross section corresponding to the arc surface 10a.

  When grinding (contouring) is performed on the workpiece 10 using the electrodeposition grindstone 1 having the electrodeposition surface 3 having the shape described above, the grinding allowance is large at the convex portion 3a of the electrodeposition surface 3. . That is, on the electrodeposition surface 3, the grinding depth with respect to the workpiece 10 differs depending on the location, the grinding volume is the largest in the convex portion 3a, and the grinding volume is the smallest in the concave portions 3b on both sides thereof. Therefore, during the grinding, the load is most applied to the convex portion 3a, and the generation of heat generation and polishing residue is greatest.

  Therefore, in the present embodiment, the grinding fluid supply hole 4 as shown in FIG. 4 is formed so that the grinding fluid can be directly supplied to the convex portion 3a having the largest grinding allowance, and the heat generation is suppressed and the polishing residue is quickly removed. Allow to drain.

  The shape of the workpiece 10 is not limited to a rectangular parallelepiped (square block shape), and may be any shape such as a shape close to the final shape of processing. For example, the shape of the molded body that can be molded may be limited due to restrictions in the molding process, etc. In such a case, after forming into a moldable shape, this is sintered and processed into a desired shape Grinding is done. Even when the workpiece 10 having various shapes is ground, a part having a large grinding allowance and a part having a small grinding allowance are generated. However, the present invention is also applicable to such a case. In this case, the grinding fluid supply hole 4 may be formed in the portion of the electrodeposition surface 3 where the grinding allowance is the largest, depending on the shape of the workpiece 10 and the grinding shape.

  As described above, the grinding fluid supply hole 4 is preferably formed in a portion where the grinding allowance (grinding volume) is the largest on the electrodeposition surface 3, and therefore, it is preferable to appropriately change it according to the shape of the electrodeposition surface 3. For example, with respect to the workpiece 10 whose upper surface as shown in FIG. 5 (a) is ground to the arc surface 10a, as shown in FIG. 5 (b), the surface opposite to the arc surface 10a is the arc surface 10b. As shown in FIG. 6, the electrodeposition surface 3 of the electrodeposition grindstone used for grinding the arc surface 10b has convex portions 3c on both sides and a concave portion 3d on the central portion 3d. In such a case, the grinding fluid supply hole 4 may be formed so that the grinding fluid can be supplied to the convex portions 3c on both sides.

  The grinding fluid supply hole 4 is formed so as to penetrate obliquely from the side surface of the disk-shaped base metal 2 of the electrodeposition grindstone 1 to the electrodeposition surface 3, and one opening portion of the grinding fluid supply hole 4. 4a is formed so as to open on the side surface of the disk-shaped base metal 2, and the other opening 4b is formed so as to open directly on the electrodeposition surface 3. Therefore, if the grinding fluid is supplied from the side surface side of the electrodeposition grindstone 1, the supplied grinding fluid is guided to the opening 4 a of the grinding fluid supply hole 4 along the side surface of the disc-shaped base metal 2. As shown by broken line arrows in FIG. 4, the liquid is directly supplied to the grinding portion from the opening 4 b of the electrodeposition surface 3 through the grinding liquid supply hole 4.

  In addition, in the electrodeposition grindstone 1 of the present embodiment, as shown in FIG. 4, the entire circumference extends beyond the position where the opening 4 a of the grinding liquid supply hole 4 of the disc-shaped base metal 2 is formed. Thus, a convex portion 5 is formed. The inner peripheral surface 5 a of the convex portion 5 is formed in contact with the opening 4 a of each grinding fluid supply hole 4, and the grinding fluid supplied from the side surface of the electrodeposition grinding stone 1 It flows on the circular surface of the disk-shaped base metal 2 toward the outer peripheral side due to the centrifugal force accompanying the rotation, and is dammed by the inner peripheral surface 5a of the convex portion 5 to the opening 4a of the grinding fluid supply hole 4. Led.

  The grinding liquid supply hole 4 may be formed at least at one place on the electrodeposition grindstone 1, but it is preferably formed at 2 to 16 places in order to efficiently supply the grinding liquid to the electrodeposition surface 3. . The number of grinding fluid supply holes 4 to be formed varies depending on the size (diameter) of the electrodeposition grindstone 1, but is preferably formed at 6 or more, more preferably 8 or more. In this example, the grinding fluid supply holes 4 are formed at eight locations. If the number of the grinding fluid supply holes 4 is small, the cooling ability may be insufficient. Conversely, if the number is too large, the area that can be ground may be reduced and the grinding ability may be reduced.

  Moreover, when forming the grinding-fluid supply hole 4 in several places, it is preferable to form in the circumferential direction of the electrodeposition grindstone 1 at equiangular intervals. When the grinding fluid supply hole 4 is formed only at one place, the electrodeposition grindstone 1 may be decentered when rotating at a high speed.

  In the present embodiment, the openings 4 a of the plurality of grinding fluid supply holes 4 are arranged on one side surface of the disk-shaped base metal 2, and grinding is performed only from one side surface of the electrodeposited grinding stone 1. However, the present invention is not limited to this. For example, the openings 4a of the grinding fluid supply holes 4 are alternately formed on both side surfaces of the disc-shaped base metal 2. It is also possible to form it. In this case, the grinding fluid may be supplied from both side surfaces of the electrodeposited grinding stone 1 and introduced into each grinding fluid supply hole 4, and the cooling effect of the grinding stone itself is promoted.

  The size of the opening 4b of the grinding fluid supply hole 4 formed so as to open to the electrodeposition surface 3 is preferably 1/8 to 1/3 of the width of the electrodeposition surface 3. As a specific numerical value, for example, in the case of a circular opening, the diameter is 1 to 3 mm. Thereby, sufficient grinding fluid can be supplied and sufficient cooling effect is expressed. When the dimension of the opening 4b is equal to or larger than the above, there is a possibility that a problem may occur in the strength of the grindstone when grinding by rotating at a high speed.

  Further, as described above, the shape of the grinding fluid supply hole 4 may be a shape that obliquely penetrates from the side surface of the disk-shaped base metal 2 to the electrodeposition surface 3, but is not limited thereto, and is perpendicular to the middle portion. It is also possible to have a bent shape or a curved shape. However, in the vicinity of the opening 4a on the side surface side of the disk-shaped base metal 2, it is preferable to have an introduction portion substantially parallel to the direction in which the grinding fluid acts on the side surface. Thereby, the efficiency of introducing the grinding fluid into the grinding fluid supply hole 4 can be improved. The cross-sectional shape of the grinding fluid supply hole 4 is not limited to a circle, but may be an ellipse, a triangle, a quadrangle, or a V shape.

  The above is the configuration of the electrodeposition grindstone. Next, a grinding method using the electrodeposition grindstone will be described. Here, first, a method for producing a rare earth sintered magnet that is an object to be processed will be briefly described, and then contour processing of the produced rare earth sintered magnet (object to be processed 10) will be described.

  The rare earth sintered magnet has, for example, a rare earth element R, a transition metal element T, and boron as main components. However, the magnet composition is not particularly limited, and may be arbitrarily selected according to the application. For example, the rare earth element R specifically means Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu. 1 type (s) or 2 or more types can be used. Among these, it is preferable that the main component as the rare earth element R is Nd because it is abundant in resources and relatively inexpensive. Moreover, as the transition metal element T, any conventionally used transition metal element can be used. For example, one or more of Fe, Co, Ni and the like can be used. Among these, from the viewpoint of magnetic properties, Fe is the main component, and it is particularly preferable to add Co that is effective in improving the Curie temperature and improving the corrosion resistance of the grain boundary phase. In addition to the rare earth element R, transition metal element T, and boron B, the inclusion of other elements is allowed. For example, elements such as Al, Cu, Zr, Ti, Bi, Sn, Ga, Nb, Ta, Si, V, Ag, and Ge can be appropriately contained. On the other hand, it is desirable to reduce impurity elements such as oxygen, nitrogen, and carbon as much as possible. In particular, the amount of oxygen that impairs magnetic properties is preferably 7000 ppm or less, more preferably 5000 ppm or less. This is because when the amount of oxygen is large, the rare-earth oxide phase, which is a nonmagnetic component, increases and the magnetic properties are deteriorated. The rare earth sintered magnet 1 to be cut is not limited to the RTB-based rare earth sintered magnet. For example, the rare earth sintered magnet may be an SmCo-based sintered magnet or the like, and it is effective to apply the grinding method of the present invention also to these.

  Rare earth sintered magnets are produced by powder metallurgy, but the manufacturing process basically consists of an alloying process, coarse pulverization process, fine pulverization process, molding process, sintering process, and aging process. . In order to prevent oxidation, most of the steps after sintering are performed in a vacuum or in an inert gas atmosphere (in a nitrogen gas atmosphere, an Ar gas atmosphere, etc.).

  In the alloying step, a raw material metal or alloy is blended according to the composition of the desired rare earth alloy powder, and melted in a vacuum or an inert gas, for example, Ar atmosphere, and cast to form an alloy. As the casting method, any method can be adopted, but the strip casting method (continuous casting method) in which a molten high-temperature liquid metal is supplied onto a rotating roll and the alloy thin plate is continuously cast is a viewpoint of productivity and the like. From the viewpoint of the form of the resulting alloy.

  As the raw material metal (alloy) used in the alloying, pure rare earth elements, rare earth alloys, pure iron, ferroboron, and alloys thereof can be used. As the alloy, a single alloy having almost the final magnet composition may be used, or a plurality of types of alloys having different compositions may be mixed so as to have the final magnet composition.

  In the coarse pulverization step, the previously cast raw alloy thin plate, ingot, or the like is pulverized until the particle size is about several hundred μm. As the pulverizing means, a stamp mill, a jaw crusher, a brown mill, or the like can be used. In order to improve the coarse pulverization property, it is effective to perform coarse pulverization after occlusion of hydrogen and embrittlement.

  After the above-described coarse pulverization step is completed, a lubricant is added to the coarsely pulverized raw material alloy powder as necessary. As the lubricant, for example, a fatty acid compound can be used, and in particular, by using a fatty acid or fatty acid amide having a melting point of 60 ° C. to 120 ° C. as a lubricant, good magnetic properties, in particular, a high degree of orientation. A rare earth sintered magnet having high magnetization can be obtained, and the strength of the compact can be adjusted to a predetermined value depending on the type and amount of addition.

  After the coarse pulverization step, a fine pulverization step is performed. This fine pulverization step is performed using, for example, an airflow pulverizer. The conditions for fine pulverization may be appropriately set according to the airflow pulverizer to be used, and the raw material alloy powder is finely pulverized until the average particle size becomes about 1 to 10 μm, for example, 3 to 6 μm. A jet mill or the like is suitable as the airflow pulverizer.

  After the pulverization step, the raw material alloy powder is formed in the magnetic field in the magnetic field forming step. Specifically, the raw material alloy powder obtained in the fine pulverization step is filled in a mold in which an electromagnet is arranged, and is molded in a magnetic field in a state where crystal axes are oriented by applying a magnetic field. The forming in the magnetic field may be either a parallel magnetic field forming in which the forming pressure and the magnetic field direction are parallel, or an orthogonal magnetic field forming in which the forming pressure and the magnetic field direction are orthogonal to each other. Further, a pulse power source and an air-core coil can be employed as the magnetic field applying means. The forming in the magnetic field may be performed in a magnetic field of 700 to 1600 kA / m, for example, at a pressure of 30 to 300 MPa, preferably about 130 to 160 MPa.

  After forming into a predetermined shape by the forming step, a sintering process is performed on the formed body in the sintering step. In the sintering process, the compact is sintered in a vacuum or in an inert gas atmosphere (such as in an Ar gas atmosphere). The sintering temperature needs to be adjusted according to various conditions such as composition, pulverization method, difference in particle size and particle size distribution, etc. For example, sintering may be performed at 1000 to 1200 ° C. for about 1 to 10 hours. It is preferable to do. In addition, in a sintering process, it is preferable to perform a degreasing process prior to sintering as needed.

  After the sintering, the obtained sintered body is preferably subjected to an aging treatment. This aging treatment is an important step in controlling the coercive force Hcj of the obtained rare earth magnet. For example, the aging treatment is performed in an inert gas atmosphere or in a vacuum. As the aging treatment, a two-stage aging treatment is preferable, and in the first aging treatment step, the temperature is maintained at a temperature of about 800 ° C. for 1 to 3 hours. Next, a first quenching step is provided for quenching to room temperature to 200 ° C. In the second stage aging treatment step, the temperature is maintained at about 600 ° C. for 1 to 3 hours. Next, a second quenching step for quenching to room temperature is provided. Since the coercive force Hcj is greatly increased by heat treatment at around 600 ° C., when aging treatment is performed in a single stage, it is preferable to perform aging treatment at around 600 ° C.

  As described above, for example, a square block-shaped rare earth sintered magnet is manufactured, and contour processing is performed on the square block-shaped rare earth sintered magnet according to the shape of the final product. At this time, by using the electrodeposition grindstone 1, it is possible to prevent heat generation and clogging.

  FIG. 7 shows a state in which contour processing of the workpiece 10 (the square block-shaped rare earth sintered magnet) is performed using the electrodeposition grindstone 1. At the time of contour processing, as shown in FIG. 7, the processing object 10 is arranged on a rail 11 having guides on both sides, and is transported by a transporting means. In the actual process, a plurality of workpieces 10 are arranged on the rail 11, but here, for the sake of simplification, one workpiece 10 is arranged on the rail 11.

  The workpiece 10 conveyed by the conveying means contacts the electrodeposition grindstone 1 that rotates at high speed in the direction of the arrow along the guide or while being biased, and is contoured into the shape of the electrodeposition surface 3. . In the contour machining, first, a grinding fluid is supplied from a grinding fluid supply nozzle 12 disposed on the side surface side of the electrodeposition grindstone 1. As the grinding liquid, water to which a rust preventive agent is added can be used.

  The grinding fluid supplied from the grinding fluid supply nozzle 12 to the side surface of the electrodeposition grindstone 1 is transmitted along the surface of the disk-shaped base metal 2 by centrifugal force, and is clogged by the inner peripheral surface 5a of the convex portion 5 to be opened. 4a leads to the grinding fluid supply hole 4. Furthermore, it is directly supplied from the opening 4b of the grinding fluid supply hole 4 to the electrodeposition surface 3 of the electrodeposition grindstone 1 to cool and discharge the polishing residue.

  At the time of contour processing, in addition to the side surface side of the electrodeposition grindstone 1, as in the case of normal grinding, the workpiece 10 is conveyed at the exit position from the electrodeposition grindstone 1 in the conveying direction of the workpiece 10. It is preferable to supply the grinding fluid in the opposite direction. In the case of this example, a grinding liquid supply nozzle 13 is installed at the outlet position, and the grinding liquid is supplied toward the electrodeposited grinding stone 1. Thereby, the supplied grinding liquid is caught between the electrodeposition surface 3 and the workpiece 10 by the rotation of the electrodeposition grindstone 1, and together with the grinding liquid supplied from the grinding liquid supply hole 4, Exhibits cooling effect and polishing residue discharge function.

  By using together the grinding fluid supplied in the direction opposite to the conveyance direction of the workpiece 10, the cooling effect can be improved and damage to the workpiece 10 can be suppressed. When the grinding fluid is not supplied from the grinding fluid supply nozzle 13 to the electrodeposition grindstone 1, cooling is insufficient at the time of grinding, and the grinding ability is reduced due to heat generation. Therefore, in a state in which the grinding resistance has become very high, the workpiece 10 being ground is forcibly pushed by the workpiece 10 that continues from behind, and breakage frequently occurs.

  As described above, at the time of contour machining, the grinding fluid is directly supplied from the grinding fluid supply hole 4 to the electrodeposition surface 3 and the grinding fluid is supplied to the electrodeposition grindstone 1 so as to face the conveying direction of the workpiece 10. As a result, it is possible to prevent heat generation during grinding and to prevent clogging due to polishing debris, and it is possible to obtain effects such as constant processing speed, stabilized workpiece dimensions, and stable production number. In addition, it is possible to reduce manufacturing costs and simplify process maintenance.

  As mentioned above, although the electrodeposition grindstone to which the present invention is applied and the embodiments of the grinding method have been described, it is needless to say that the present invention is not limited to these embodiments. Can be modified.

  Next, specific examples of the present invention will be described.

EXAMPLE A rectangular block-shaped rare earth sintered magnet of 50 mm × 10 mm × 3 mm was used as a workpiece, and contour processing was performed with an electrodeposition grindstone having the electrodeposition surface shape shown in FIG. As the electrodeposition grindstone, a diamond abrasive grain electrodeposited was used, and the abrasive grain diameter of the diamond abrasive grain was set to 100 μm to 300 μm. Moreover, as shown in FIG.1 and FIG.2, 8 places of the grinding fluid supply holes were formed in the said electrodeposition grindstone, and these were arrange | positioned at equal angular intervals in the circumferential direction.

  In the contour processing (grinding), as shown in FIG. 7, the grinding fluid was supplied from two directions, that is, the side surface of the electrodeposition grindstone and the direction opposite to the conveying direction of the workpiece. In grinding, the electrodeposition grindstone was rotated at 4500 rpm, and the conveyance speed (feed) of the workpiece was set to 300 mm / min. As a result, it was found that approximately 23,000 workpieces could be ground and the grinding ability was remarkably improved. In the grinding, the same grinding was attempted with only the side surface of the electrodeposition grindstone being supplied (that is, only from the grinding fluid supply hole). However, breakage occurred frequently, and the grinding fluid was supplied from the two directions. It was also found effective.

Comparative Example The grinding fluid supply hole was not formed in the electrodeposition grindstone, and the grinding fluid was supplied only from the direction opposite to the conveying direction of the workpiece. As a result, the grinding speed decreased when approximately 15,000 workpieces were ground, and defective samples were generated due to breakage.

Examination of workpieces First, grinding of ferrite sintered magnets and NdFeB sintered magnets was attempted with the same grindstone as in the comparative example. Specifically, 10000 ferrite sintered magnets and NdFeB sintered magnets having the same dimensions as in the example were ground using an electrodeposition grindstone in which no grinding fluid supply holes were formed. As a result, it was found that a large difference occurred in the normal direction grinding resistance. For example, when the depth of cut was 0.1 mm, there was no difference in grinding resistance at the beginning of grinding, but a large difference was observed between the ferrite sintered magnet and the NdFeB sintered magnet in the grinding resistance after grinding 10,000 pieces. Specifically, in the ferrite sintered magnet, the grinding resistance changed in the range of 5 to 15 kgf from the beginning of grinding to after the 10,000 grinding, whereas in the NdFeB sintered magnet, the grinding resistance after the 10,000 grinding. Markedly increased to 30-50 kgf.

  Therefore, next to the ferrite sintered magnet and the NdFeB sintered magnet having the same dimensions as in the example, the electrodeposition grindstone in which the grinding fluid supply hole is formed is used as in the example, and the side surface of the electrodeposited grindstone and the conveyance of the workpiece 10,000 pieces were ground while supplying a grinding liquid from two directions opposite to the direction. As a result, even in the grinding of the NdFeB sintered magnet, there was almost no increase in the grinding resistance after grinding 10,000 pieces. Therefore, it can be said that the electrodeposition grindstone of the present invention is highly effective when applied to grinding rare earth sintered magnets such as NdFeB sintered magnets.

It is a schematic perspective view which shows an example of the electrodeposition grindstone to which this invention is applied. It is a schematic sectional drawing of the electrodeposition grindstone shown in FIG. It is a figure explaining an outline process, (a) shows the shape of the workpiece before grinding, and (b) shows the shape of the workpiece after grinding. The shape of the electrodeposition surface of the electrodeposition grindstone which performs the grinding process shown in FIG. 3, and the grinding fluid supply hole are shown. It is a figure explaining the other example of a contour process, (a) shows the shape of the workpiece before grinding, (b) shows the shape of the workpiece after grinding. The shape of the electrodeposition surface of the electrodeposition grindstone which performs the grinding process shown in FIG. 5, and the grinding fluid supply hole are shown. It is a schematic diagram which shows the mode of the contour process using the electrodeposition grindstone shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrodeposition grindstone, 2 Disc shaped metal base, 3 Electrodeposition surface, 4 Grinding fluid supply hole, 4a, 4b Opening part, 5 Convex part, 5a Inner peripheral surface, 10 Work object, 11 Rail, 12, 13 Grinding fluid supply nozzle

Claims (9)

An electrodeposition grindstone is formed by electrodepositing abrasive grains on the outer peripheral surface of a disk-shaped base metal to form a contour of a workpiece,
A grinding fluid supply hole extending from the side surface of the disk-shaped base metal to the electrodeposition surface is formed so as to penetrate, and one opening of the grinding fluid supply hole is formed so as to open to the outside on the electrodeposition surface. An electrodeposited whetstone characterized by   2. The electrodeposition grindstone according to claim 1, wherein the opening is formed in a position where the grinding allowance is the largest in the contour processing or in the vicinity thereof in the electrodeposition surface.   The said grinding-fluid supply hole is formed in multiple numbers by the circumferential direction of the said disk-shaped base metal, The said opening part is formed in multiple numbers by the circumferential direction of the said electrodeposition surface, The 1st or 2 characterized by the above-mentioned. Electrodeposition whetstone.   The number of the grinding fluid supply holes and the openings is 2 to 16, and the openings are formed at substantially equal angular intervals in the circumferential direction of the electrodeposition surface. Electrodeposition whetstone.   The electrodeposition grindstone according to any one of claims 1 to 4, wherein the size of the opening is 1/8 to 1/3 of the width of the electrodeposition surface.   The electrodeposition grindstone according to any one of claims 1 to 5, wherein an annular convex portion is formed on an outer peripheral side of the opening on the side surface of the disc-shaped base metal of the grinding liquid supply hole. .   Using the electrodeposition grindstone according to any one of claims 1 to 6, a grinding liquid is injected from a side surface of a disk-shaped base metal of the electrodeposition grindstone, and the electrodeposition surface is formed through the grinding liquid supply hole. A grinding method characterized by performing contour processing of a workpiece while supplying a grinding fluid.   The grinding method according to claim 7, wherein a grinding liquid is also supplied to the electrodeposition grindstone from the electrodeposition grindstone exit side of the workpiece.   The grinding method according to claim 7 or 8, wherein the object to be processed is a rare earth sintered magnet.

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