JP5192763B2 - Method for producing superabrasive vitrified grinding wheel - Google Patents

Description

The present invention relates to a method for producing a superabrasive vitrified grindstone having a grindstone structure in which superabrasive grains and filler particles are three-dimensionally bonded by a molten glass body.

  With superabrasive vitrified wheels that use highly durable and hard superabrasive grains, the temperature of the grinding point during the grinding operation becomes extremely high, and the higher the grinding efficiency, the higher the grinding efficiency. It has been a problem to damage (workpiece) such as grinding burns and grinding cracks. Thus, in the grinding process using the superabrasive vitrified grindstone, the grinding efficiency and the grinding quality are in conflict with each other, and various studies have been conducted so far. It has become known that grinding burn is likely to occur, and if there is variation in the distribution of vitrified bonds, the above-mentioned grinding burn and cracks are likely to occur in a portion where there are many bonds.

  On the other hand, a superabrasive vitrified grindstone has been proposed in which the number of abrasive grains per unit volume and the amount of vitrified bonds in the unit volume are reduced to increase the porosity. However, in the superabrasive vitrified grindstone with such a configuration, the grindstone hardness decreases and the life is sacrificed, or the firing deformation becomes large, and it becomes difficult to maintain the distance between the grits. Depending on the conditions, it is inevitable that burns occur due to the aggregation of abrasive grains generated on the grinding surface and the density of vitrified bond distribution. In addition, it is conceivable to make the abrasive grains finer, but there are disadvantages that the abrasive retention force is reduced, the wear of the grinding wheel is increased, the dress interval is shortened, and the grinding wheel life is shortened.

Moreover, the superabrasive vitrified grindstone disclosed in Patent Document 1 is an example thereof, and by mixing inorganic hollow particles, the agglomeration of abrasive grains is reduced and a high porosity is realized.
Japanese Patent Publication No. 6-24700

  By the way, in the conventional superabrasive vitrified grindstone, vitrified bonds are likely to aggregate around the inorganic hollow particles, and grinding burns starting from the aggregation points of the vitrified bonds occur, while vitrified bonds are sparse. In such a place, there is a problem that the holding power of the grindstone becomes weak and the abrasive grains fall off locally and the amount of wear increases.

The present invention has been made against the background described above, and the object of the present invention is to achieve the above-mentioned conventional superabrasive vibridized whetstone without defects, that is, an ultra-low whetstone generation and a long whetstone life. It is providing the manufacturing method of an abrasive vitrified grindstone.

  As a result of various studies conducted by the present inventors against the background described above, superabrasive grains that greatly contribute to grinding performance and fillers that do not contribute to grinding performance as much as the superabrasive grains but constitute a grindstone structure together with the abrasive grains If the number ratio within a specified range is relative to the number of particles, the grindstone structure composed of superabrasive particles and filler particles keeps the distance between them almost uniform without agglomerating the superabrasive particles. It has been found that a large number of unit structures that can be produced are produced, and this can significantly prevent grinding burn, and can dramatically improve the grinding wheel wear amount and the dressing interval. The present invention has been made based on such knowledge.

That is, the gist of the invention according to claim 1 for achieving the above object is that superabrasive grains and filler particles having an average particle size of 0.5 to 1.5 times the superabrasive grains. Doo is within at least a portion of the abrasive structure comprising linked by melting glass body, wherein the superabrasive and unit structure sterically repeated filler particles as a reference, the filler particles as the basic unit the number of particles that super A method for producing a superabrasive vitrified grindstone composed of 1.0 to 5.0 per abrasive grain, wherein (a) one of the superabrasive grains is formed on the outer surface of the superabrasive grain. / 10 superabrasive bond coating step of forming a coating comprising a vitrified bond and a binder having an average particle size of / 10 or less, and (b) the vitrified bond and the binder on the outer surface of the filler particles Corty consisting of (C) the superabrasive grains in which the coating is layered on the outer surface in the superabrasive bond coating process, and the filler particle bond coating process in the filler particle bond coating process. A mixing step of uniformly mixing filler particles having a coating formed in a layer on the outer surface; and (d) adding the mixed material uniformly mixed in the mixing step into a molding space in a press die. A molding step of molding a predetermined molded product by pressing, and (e) melting the vitrified bond at the same time that the viscous binder disappears by firing the molded product molded in the molding step, And a firing step for obtaining a superabrasive vitrified grindstone having a grindstone structure .

According to the method for manufacturing a superabrasive vitrified grindstone according to the first aspect of the present invention, the superabrasive grains that make a relatively large contribution to the grinding performance and the filler particles that constitute the grindstone structure together with the superabrasive grains are predetermined. In a superabrasive vitrified grindstone bonded by a molten glass body in a state of being filled in a space, a unit structure that repeatedly appears three-dimensionally based on the superabrasive grains and filler particles in at least a part of the grindstone structure However, since the number of basic unit particles is 1.0 to 5.0 for each superabrasive particle, the superabrasive particles and the filler particles are in a body-centered cubic lattice shape. A grindstone structure bonded by vitrified bonds in a relative position that results in a filling structure in the form of a face-centered cubic lattice and / or a filling structure in a hexagonal close-packed structure. The relatively uniform distance is formed between the super abrasive grains are appropriately restrict to aggregate with each other, superabrasive vitrified abrasive occurrence of grinding burn is obtained less and longer grinding wheel life can be obtained. In addition, since the coating composed of vitrified bond and binder is formed on the outer surface of the superabrasive grains and the filler, respectively, there is an advantage that further fluidity is imparted.

According to the method for manufacturing a superabrasive vitrified grindstone of the invention according to claim 2, the unit structure forms a body-centered cubic lattice-like filling structure including one superabrasive grain and one filler particle. Is. In this case, the unit structure constituting at least a part of the grindstone structure of the superabrasive vitrified grindstone is a body-centered cubic lattice-like filling structure including one superabrasive grain and one filler particle. Therefore, the superabrasive grains are preferably limited to agglomerate with each other, a relatively uniform distance is maintained between the superabrasive grains, and there is little occurrence of grinding burn and a long grinding wheel life. The resulting superabrasive vitrified wheel is obtained.

According to the method for producing a superabrasive vitrified grindstone of the invention according to claim 3, in the body-centered cubic lattice-like filling structure, one superabrasive grain is located at the eight adjacent positions. They are bound by the molten glass body in a state of being spatially surrounded by particles. In this way, the unit structure included in the grindstone structure of the superabrasive vitrified grindstone is a state in which one superabrasive grain is spatially surrounded by eight filler particles located at the nearest position. Therefore, the superabrasive grains are preferably limited to agglomerate with each other and the filler particles are interposed between the superabrasive grains to form a uniform distance. The

According to the method for manufacturing a superabrasive vitrified grindstone of the invention according to claim 4, the unit structure forms a face-centered cubic lattice-shaped filling structure including one abrasive grain and three filler particles. It is. In this case, the unit structure constituting at least a part of the grindstone structure of the superabrasive vitrified grindstone is a body-centered cubic lattice-like filling structure including one superabrasive grain and three filler particles. Therefore, the superabrasive grains are preferably limited to agglomerate with each other, a relatively uniform distance is formed between the superabrasive grains, and there is little occurrence of grinding burn and a long grinding wheel life. The resulting superabrasive vitrified wheel is obtained.

According to the method for producing a superabrasive vitrified grindstone of the invention according to claim 5, in the filling structure in the face-centered cubic lattice shape, one of the abrasive grains is a filler particle located at 12 positions of the nearest neighbor position. Are joined by the molten glass body in a spatially surrounded state. In this way, the unit structure included in the grindstone structure of the superabrasive vitrified grindstone is a state in which one superabrasive grain is spatially surrounded by 12 filler particles located at the nearest position. Therefore, the superabrasive grains are preferably limited to agglomerate with each other, and the filler particles are interposed between the superabrasive grains to provide a relatively uniform distance. It is formed.

According to the method for producing a superabrasive vitrified grindstone of the invention according to claim 6, the unit structure forms a six-way finely packed structure including one abrasive grain and five filler particle particles. . In this case, the unit structure constituting at least a part of the grindstone structure of the superabrasive vitrified grindstone has a 6-way fine structure including one superabrasive grain and five filler particles. Due to the structure, the superabrasive grains are preferably limited to agglomerate with each other, a relatively uniform distance is formed between the superabrasive grains, and there is little occurrence of grinding burn and a long grinding wheel life is obtained. A superabrasive vitrified wheel is obtained.

According to the method for manufacturing a superabrasive vitrified grindstone of the invention according to claim 7, in the 6-side close-packed structure, one superabrasive grain is located at 12 positions of the nearest neighbor position and the second closest position. Are bonded by the molten glass body while being spatially surrounded by filler particles. The unit structure included in the grindstone structure of the superabrasive vitrified grindstone is a state in which one superabrasive grain is spatially surrounded by filler particles located at 12 positions of the nearest neighbor position and the second closest position. Therefore, the superabrasive grains are preferably limited to agglomerate with each other, and the filler particles are interposed between the superabrasive grains to provide a relatively uniform distance. It is formed.

According to the method for manufacturing a superabrasive vitrified grindstone of the invention according to claim 8, the center value of the grindstone hardness occupies an area of 90% or more of the whole on the surface of the grindstone structure. In this way, the unit structure is uniformly dispersed in the grindstone structure, and there is little occurrence of grinding burn and a long grindstone life can be obtained.

According to the method for manufacturing a superabrasive vitrified grindstone of the invention according to claim 9, the superabrasive grain has a coarse grain size of # 325 or more, for example, a grain size classified into any of # 325 to # 80. It is. In this way, since super-abrasive grains with coarse grain size of # 325 or more are used, the grindability is improved by the above-mentioned dense filling property rather than the inconvenience in grinding due to the small diameter of the super-abrasive grains. There is an advantage that the advantages of In addition, since each mesh is classified, the unit structure is easily configured by using superabrasive grains having a narrow grain size distribution and uniform grain sizes.

According to the method for producing a superabrasive vitrified grindstone of the invention according to claim 10, the filler particles have a particle size distribution in which the number within a range of ± 15% centering on the center particle size occupies 90% or more. It is what you have. In this way, since the filler particles have a particle size distribution in which the number in the range of ± 15% centering on the center particle size occupies 90% or more, the particle size distribution of the superabrasive grains is narrow. The unit structure is easily formed by using superabrasive grains having a uniform particle diameter.

According to the method for producing a superabrasive vitrified grindstone of the invention according to claim 11, the superabrasive grains are superabrasive grains such as diamond abrasive grains and CBN abrasive grains, and the filler particles are glass balloons, shirasu balloons, etc. Inorganic hollow particles. In this way, it is possible to obtain a superabrasive vitrified grindstone that generates less grinding burn and has a long grindstone life.

Here, preferably, the superabrasive grain having a grain size of # 325 or more is a grain size (# 325/400) that passes through a 325 mesh screen and stops on a 400 mesh screen, for example, an average grain size. (D _S -50: JIS R6002, B4130) is an abrasive grain of 50 μm or more. The # 80 grain size is a grain size (# 80/100) that passes through an 80-mesh screen and stops on a 100-mesh screen. It is provided.

  Preferably, the superabrasive grains and filler particles do not have to be completely spherical, but are desirably spherical particles or particles having a shape close thereto. For example, the ratio of minor axis / major axis is 0.5 or more in a press molding process in which a grinding stone material mixed with abrasive grains, filler particles, vitrified bond, adhesive, etc. is pressed in a mold. This is desirable because a dense, cubic lattice-like filling structure, face-centered cubic lattice-like filling structure, or hexagonal close-packed structure-like filling structure is formed.

  Similarly, in the press molding process of the grindstone material, a cubic lattice-like filling structure, a face-centered cubic lattice-like filling structure, or a hexagonal close packed structure-like filling structure is formed. The average particle size is desirably in the range of 0.5 to 1.5 times, preferably 0.7 to 1.0 times the average particle size of the abrasive grains.

  Further, the superabrasive vitrified bond preferably has an average diameter within the range of 0.01 to 0.2 times smaller than the average particle diameter of the superabrasive grains or filler particles before firing. The particle size is such that the number of particles having a diameter equal to or less than twice the center particle size is 70% by number or more. The superabrasive vitrified bond preferably has a minor axis / major axis ratio of 0.7 or more, for example, 0.7 to 0.9. According to this, the filling structure by the superabrasive grains and the filler particles formed at the time of press molding can be easily formed, and it is suitably suppressed that the filling structure changes at the time of firing.

The superabrasive vitrified bond is preferably a rounded particle obtained by wet pulverization, which is desirable for filling at the time of press molding, and a simple substance when a molding pressure of 300 kg / mm ² is applied. It is desirable that the filling rate is 55% by volume or more, and the apparent density (bulk specific gravity) is 1.2 or more by measurement based on the standard of ASTM D2840. Since the single filling rate and the apparent density are affected by the shape of the bidified bond, the shape of the bidified bond is indirectly specified.

Preferably, the superabrasive grains are composed of diamond abrasive grains and CBN abrasive grains. General abrasive grains such as aluminum oxide (Al ₂ O ₃ ) -based alumina abrasive grains, silicon carbide (SiC) -based silicon carbide abrasive grains represented by GC abrasive grains, and zirconia abrasive grains are regarded as filler particles. . Also, those not having an average particle size of 0.5 to 1.5 times the average particle size of superabrasive grains are not counted as fillers.

  Preferably, the filler particles are not only composed of inorganic hollow particles such as ceramic (glass) balloons typified by Shirasu balloons, but also solid inorganic particles such as ceramic balls, Abrasive grains, recycled abrasive grains, massive abrasive grains, and the like may be used.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are simplified or conceptualized as appropriate, and the dimensional ratios and shapes of the respective parts are not necessarily drawn accurately.

  FIG. 1 shows a vitrified grindstone 10 for end face grinding which is a superabrasive vitrified grindstone of one embodiment of the present invention. This vitrified grindstone 10 is made of a metal disc-shaped base metal 12 and an annular grinding plane 14 that sticks along the outer peripheral edge of the base metal 12 to protrude in a direction parallel to the rotational axis toward one surface. Are provided with a plurality of segment grindstones 16.

  As shown in FIG. 2, when grinding an end surface 19 of a steel work material 18 such as a crank journal part or a camshaft front part, the work material 18 and the vitrified grindstone 10 are rotated, When the grinding plane 14 of the vitrified grindstone 10 is pressed against the end face 19 of the work material 18, the end face 19 is ground.

The segment grindstone 16 of the vitrified grindstone 10 is manufactured, for example, according to the process diagram shown in FIG. That is, first, in the superabrasive bond coating step P1, superabrasive grains 20 having a coarse grain size of # 325 or more, and glass powder excellent in high impact resistance and heat resistance that are frited after melting and are superabrasive. By being mixed with a powdered vitrified bond having an average particle size of 1/10 or less of the grains 20 together with a well-known binder (molding aid) such as a synthetic paste represented by dextrin. The coating composed of the vitrified bond and the binder is formed in a layered manner on the outer surface of the superabrasive grains 20, and is further dried to provide further fluidity. Also in the filler particle bond coating step P2, for example, filler particles 22 made of inorganic hollow particles such as glass balloons and inorganic solid particles and vitrified bonds similar to the above are used together with well-known binders such as dextrin. By mixing, the coating composed of the vitrified bond and the binder is formed in a layered manner on the outer peripheral surface of the filler particle 22, and is further dried to give further fluidity. As the filler particles 22, for example, those having an average particle diameter of 0.5 to 1.5 times the average particle diameter of the superabrasive grains 20 are used. The superabrasive grains 20 have a particle size of # 325 / # 400, for example, an average particle size (d _S -50: JISR6002, B4130) of about 50 μm.

The vitrified bond is a powder of glass excellent in high impact resistance and heat resistance, for example, SiO ₂ 50 to 80 wt% oxide composition, B ₂ O ₃ 10 to 20 wt%, Al ₂ O _3. 5 to 15% by weight, glass frit in which the total of metal oxides selected from CaO, MgO, K ₂ O, and Na ₂ O is 8 to 15% by weight, or oxide composition is SiO ₂ 70 to 90% by weight, B It is composed of glass frit such as ₂ O ₃ 10 to 20% by weight, Al ₂ O ₃ 1 to 5% by weight, Na ₂ O ₃ 1 to 5% by weight, that is, powder glass fritted after melting. Vitrified bonds may be added with clay or the like in the above powder glass.

The vitrified bond has a diameter smaller than the average particle diameter of the superabrasive grains 20 or the filler particles 22, for example, an average particle diameter in the range of 0.01 to 0.2 times, and twice the center particle diameter. A powder having a distribution in which the number of particles having the following diameters is 70% by number or more. FIG. 4 shows an example of the particle size distribution of the vitrified bond. In this example, the center particle size is 3 μm, the half-value width is 1 to 8 μm, and the number of particles having a particle size of 6 μm or less is about 80% by number. This vitrified bond preferably has a minor axis / major axis ratio of 0.7 or more, for example, in the range of 0.7 to 0.9. Further, this vitrified bond is preferably particles with rounded corners obtained by wet pulverization, the single filling rate when a molding pressure of 300 kg / mm ² is applied is 55% by volume or more, and ASTM D2840 The apparent density (bulk specific gravity) is 1.2 or more according to the measurement conforming to the standard.

In the present embodiment, the filler particles 22 are composed of inorganic hollow particles such as a ceramic (glass) balloon represented by a shirasu balloon. The filler particles 22, the apparent density of 0.6~0.9g / cm ^3, the bulk density of 0.25~0.42g / cm ^3, compressive strength of 70N / mm ^2, 1600 ℃ melting point above, It is a closed type hollow particle having substantially zero water absorption. The average particle diameter of the filler particles 22 is in the range of 0.5 to 1.5 times, preferably 0.7 to 1.0 times the average particle diameter of the superabrasive grains 20. Is set to FIG. 5 shows an example of the particle size distribution of the filler particles 22. In this example, the distribution is such that the minimum particle size is 30 μm, the center particle size is 45 μm, and the maximum particle size is 75 μm.

  Next, in the mixing step P3, the superabrasive grains 20 and the filler particles 22 each coated with the above-described coating are set in advance, for example, in a superabrasive: filler particle ratio within a range of 1: 1 to 5. The particles are mixed with a well-known binder such as dextrin at a ratio that gives a ratio of the number of particles and mixed uniformly there. Next, in the molding step P4, the mixed material is filled in a predetermined press mold for forming a cylindrical molding space, and is formed into segments by being pressed by a press. In the firing step P5, the molded product that has undergone the molding step P4 is sintered in a predetermined firing furnace under a firing condition in which a temperature of about 900 ° C. is indicated by holding for 0.5 hours. By this sintering, the binder is burned out and the vitrified bond is melted, so that the vitrified bond 24 in which the superabrasive grains 20 and the filler particles 22 are melted is formed as shown in the vitrified grindstone structure diagram of FIG. And a segmented vitrified grindstone, that is, a segment grindstone 16 is formed. Next, in the bonding process P <b> 6, the sintered segment grindstones 16 are bonded in a state of being arranged in the circumferential direction along the outer peripheral edge of the base metal 12. In addition, this adhesion process P6 is not performed when it shape | molds in the said process P4 cylindrically and a base metal is not used. In the finishing step P7, the vitrified grindstone 10 is manufactured by mechanically finishing with a cutting or grinding tool so that the outer dimensions such as the outer peripheral surface and the end surface become predetermined product standards, and the inspection step P8 is performed. Shipped after.

  According to the vitrified grindstone 10 having a grindstone structure as shown in FIG. 10 manufactured as described above, the superabrasive grains 20 that make a relatively large contribution to the grinding performance, and the grindstone together with the superabrasive grains 20 A vitrified grindstone structure bonded with a vitrified bond (molten glass body) 24 in a state where the filler particles 22 constituting the structure are filled in a predetermined space is formed, and superabrasive grains 20 are formed in the grindstone structure. The unit structure that is three-dimensionally repeated with reference to the filler particles 22 is composed of 1 to 5 filler particles per superabrasive particle as the number of basic unit particles. In the relative position state in which the filler particles 22 constitute a body-centered cubic lattice-shaped packing structure, a face-centered cubic lattice-shaped packing structure, or a hexagonal close-packed packing structure. Since a grindstone structure bonded by the id bond 24 is obtained, the superabrasive grains 20 are preferably limited to agglomerate with each other by the interposition of the filler particles 22, and a relatively uniform distance is formed between the superabrasive grains 20. As a result, there is little occurrence of grinding burn and a long wheel life can be obtained.

FIG. 6 shows one possible structure when the superabrasive grains 20 and the filler particles 22 are assumed to be spherical, and can be taken when the superabrasive grains 20 and the filler particles 22 are closely packed in the space. it is a conceptual diagram showing a unit structure G _T cubical in body-centered cubic lattice-like filling structure. In the unit structure G _T of the cube-shaped, one superabrasive 20 is located in the center of the cube, eight of the filler particles 22 are located on the corner of the eight cubes. Eight of the filler particles 22, so by volume can have only divided into 1/8 by other unit structure G _T adjacent within a predetermined unit structure G _T, after all, in one unit structure G _T The space is occupied by one superabrasive grain 20 and one filler particle 22. Therefore, superabrasive 20 and filler particles 22 by the number ratio of 1: 1 when uniformly mixed in the vicinity proportion of such filling structure G _T is predominantly formed, one superabrasive 20 Is surrounded by eight filler particles 22 located at the closest position, and the interval between the superabrasive grains 20 becomes a substantially constant value due to the interposition of the filler particles 22.

FIG. 7 shows a surface which is one of the structures that can be taken when the superabrasive grains 20 and the filler particles 22 are filled in the space, assuming that the superabrasive grains 20 and the filler particles 22 are spherical. it is a conceptual diagram showing a unit structure G _M cubical in centered cubic lattice-like filling structure. In the unit structure G _M of the cubic, the one of the filler particles 22 located in the center of the six surfaces constituting the outer surface of a cube, but the filler particles 22 are present in six, predetermined since in the unit structure G _M can only have been divided into 1/2 by other neighboring unit structure G _M volume, the filler particles 22 occupy three partial volumes in the unit structure G _M. Eight superabrasive 20 is located on the corner of eight cubes, so by volume can have only divided into 1/8 by other unit structure G _M adjacent within a predetermined unit structure G _M, superabrasive 20 occupies one portion of the volume in the unit structure G _M. After all, the space within one unit structure G _M is as a basic unit the number of particles, occupied by a single ultra abrasive grain 20 and the three filler particles 22. Therefore, in superabrasive 20 and filler particles 22 and the number ratio of 1: When it is uniformly mixed in the vicinity ratio of 3, such filling structure G _M is predominantly formed, one superabrasive 20 is surrounded by 12 filler particles 22 located at the closest position, and the interval between the superabrasive grains 20 often becomes a constant value due to the interposition of the filler particles 22. The number of basic unit particles is composed of one superabrasive grain 20 and three filler particles 22.

FIG. 8 shows one possible structure when the superabrasive grains 20 and the filler particles 22 are assumed to be spherical, and can be taken when the superabrasive grains 20 and the filler particles 22 are closely packed in the space. it is a conceptual diagram showing a unit structure G ₆ of 6 prismatic in hexagonal close-packed structure. In the unit structure G ₆ of the hexagonal column shape, the superabrasive 20 is located respectively in the center of the end face of the hexagon, the filler particles 22 are exposed and the corner of the 12 points of the hexagonal prism, the side surface between the end faces 5 It is located in the place. Since the hexagonal end two superabrasive located surface 20 only it has been divided into 1/2 by other unit structure G ₆ adjacent volume within a predetermined unit structure G _6, the unit structure G ₆ It occupies a volume of one. Filler particles 22 in place 12, because within a predetermined unit structure G _T have only divided into 1/6 by other unit structure G ₆ adjacent volume, eventually, in one unit structure G ₆ It occupies two volumes in the space. Further, Five-filler located offices particles 22 is divided by a unit structure adjacent occupies a volume of approximately three minutes it is within a predetermined unit structure G _6. After all, in one unit structure G ₆ , it is occupied by one superabrasive grain 20 and five filler particles 22. For this reason, when the superabrasive grains 20 and the filler particles 22 are uniformly mixed in the vicinity of a ratio of 1: 5, the unit structure G ₆ is mainly formed, and one superabrasive grain 20 is formed. Is surrounded by twelve filler particles 22 located at the closest position and twelve filler particles 22 located at the second closest position, and the interval between the superabrasive grains 20 is determined by the inclusion of the filler particles 22. It becomes a substantially constant value, and grinding burn is suitably reduced, and a long life of the grindstone can be obtained.

  However, the advantage of improving the grindability by such a dense filling structure can be obtained regardless of the particle size of the superabrasive grain 20, but in particular, in the superabrasive grain 20 having a grain size smaller than # 325, Grinding inconvenience due to the reduction of the diameter of the superabrasive grain 20 becomes conspicuous. However, in the superabrasive grain 20 having a coarse grain size of # 325 or more, the grindability is improved by the above-described dense filling ability. The benefits are much higher.

  Hereinafter, using Example 1 and Example 2, the number or distribution of the filler particles 22 is controlled with respect to the superabrasive grain 20 having a coarse particle size of # 325 or more, and the coarse particle size of # 325 or more is provided. The data which shows the point from which the special effect is acquired in the range whose number ratio of the superabrasive grain 20 and the filler particle 22 was 1: 1 to 5 are shown.

First, a comparative example sample A similar to the segment grindstone 16 of FIG. 1 was prepared using the same steps as those of the embodiment of FIG. 3 except that the materials shown in the preparation table A were used. Next, Example Sample B and Example Sample C having the same shape as Comparative Example Sample A were prepared using the same steps as in the Example of FIG. 3 described above except that the materials shown in Formulation Table B and Formulation Table C were used. The vitrified grindstones 10 were respectively prepared. In Comparative Sample A, Example B and Example C, superabrasive grains (CBN abrasive grains) 20 having the same material and size are used. In Comparative Sample A, however, they are inorganic hollow particles. The number N _s of the filler particles 22 is ½ of the number N _m of the superabrasive grains 20, and the filler particles 22 (# 60/80) are formed in the superabrasive grains 20 (# 80/100). On the other hand, it has a slightly coarse particle size, that is, a large average particle size. On the other hand, the number N _s of filler particles 22 of Example Sample B is one time the number N _m of superabrasive grains 20, and the filler particles 22 are superabrasive grains 20 (# 80/100). The number N _s of filler particles 22 of Example Sample C is 5 times the number N _m of superabrasive grains 20, and the filler particles 22 No. 22 (# 170/200) has a fine particle size, that is, an average particle size of about 1/2 of that of the superabrasive grains 20 (# 80/100). FIG. 9 is a photomicrograph showing an enlarged surface of Comparative Sample A, and FIG. 10 is a photomicrograph showing an enlarged surface of Example Sample C.

(Formulation A for Comparative Sample A)
Number of superabrasive grains N _m : Number of filler particles N _s 1: 0.5
Abrasive grain concentration: 100
Abrasive grains: CBN abrasive grains (# 80/100) 25 parts by volume Filler particles: inorganic hollow particles (# 60/80) 20 parts by volume Vitrified bond 18 parts by volume
Amount of paste 6 parts by volume

(Formulation B for Example Sample B)
Number of superabrasive grains N _m : number of filler particles N _s 1: 1
Abrasive grain concentration: 100
Superabrasive grain: CBN abrasive grain (# 80/100) 25 parts by volume Filler particles: inorganic hollow particles (# 80/100) 20 parts by volume Vitrified bond 18 parts by volume
Amount of paste 6 parts by volume

(Formulation C for Example Sample C)
Number of superabrasive grains N _m : Number of filler particles N _s 1: 5
Abrasive grain concentration: 100
Superabrasive grains: CBN abrasive grains (# 80/100) 25 parts by volume Filler particles: inorganic hollow particles (# 170/200) 20 parts by volume Vitrified bond 18 parts by volume
Amount of paste 6 parts by volume

  FIG. 11 shows the result of optically measuring the interval B ′ of the superabrasive grains 20 for the comparative sample A and the example sample C using a scaled microscope. In FIG. 11, the one-dot chain line indicates the distribution of the comparative sample A, and the solid line indicates the distribution of the example sample C. The distribution of Example Sample C shows a normal distribution type graph in which the peak exists only near the ideal 2 (twice the average particle diameter of superabrasive grains), and is relatively uniform among the abrasive grains 20. It is clear that a proper interval is formed. On the other hand, in the distribution of the comparative sample A, a peak is formed at a position near 1.5, which is considered to be too far away from 1.5 indicating that the simultaneous interval of the abrasive grains is short and clogged. Yes.

  FIGS. 12 to 17 show the surfaces of Comparative Sample A and Example Sample C using a hardness meter of a type in which the hardness is measured by a push-in amount when a load of 60 kgf is applied with a 1/4 inch diameter tip sphere. FIG. 5 is a diagram showing a hardness distribution by measuring a number of hardnesses in a surface having a depth of 1 mm and a surface having a depth of 2 mm, and classifying the hardness into three stages. In this hardness distribution, a region indicated by white indicates a range of hardness 90 to 105, a region indicated by rough diagonal lines indicates a range of hardness 75-90, and a region indicated by fine diagonal lines indicates a range of hardness 50-75. Is shown.

  12, 13 and 14 show the hardness distribution on the surface of the comparative sample A, the surface having a depth of 1 mm, and the surface having a depth of 2 mm. In FIG. 12, the area indicated by white is 20%, the area indicated by rough diagonal lines is 77%, and the area indicated by fine diagonal lines is 3%. In FIG. 13, the area indicated by white is 6%, the area indicated by rough diagonal lines is 77%, and the area indicated by fine diagonal lines is 17%. In FIG. 14, the area indicated by white is 12%, the area indicated by rough diagonal lines is 77%, and the area indicated by fine diagonal lines is 10%. FIGS. 15, 16, and 17 show the hardness distributions on the surface of Example Sample C, the surface having a depth of 1 mm, and the surface having a depth of 2 mm. In FIG. 15, the area indicated by white was 3%, the area indicated by rough diagonal lines was 94%, and the area indicated by fine diagonal lines was 3%. In FIG. 16, the area indicated by white is 1%, the area indicated by rough diagonal lines is 95%, and the area indicated by fine diagonal lines is 3%. In FIG. 17, the white area is 3%, the rough hatched area is 97%, and the fine hatched area is 0%. In Comparative Sample A, the value in the vicinity of the center of hardness (region indicated by a rough diagonal line) was 77% at the maximum at any depth surface, but in Example Sample C, at any depth surface. Is 94% or more, and the value near the hardness center is assumed to be uniform on the surface of the vitrified grindstone.

  FIGS. 18 and 19 show the surfaces (wheel surfaces) of Comparative Example Sample A and Example Sample C after dressing in order to evaluate the dressing property of the surface of the vitrified wheel by the diamond dresser of Comparative Example Sample A and Example Sample C. It is the figure which displayed the uneven | corrugated distribution for the result of having measured the unevenness | corrugation of this using the surface roughness measuring apparatus, classifying the depth of the unevenness | corrugation into the layer of three steps. In this uneven distribution, a region indicated by white indicates a range of depth 0 to −60 μm, a region indicated by rough diagonal lines indicates a range of −60 to −120 μm, and a region indicated by fine diagonal lines is a depth − The range of 120 μm or less is shown. In FIG. 18, since the patterns of the layers are connected to each other, it is estimated that the superabrasive grains 20 are aggregated. In FIG. 19, since the pattern of each layer is fine and discontinuous, it is estimated that the superabrasive grains 20 are scattered and scattered.

  20, FIG. 21, and FIG. 22 show the results of grinding tests under the test conditions shown below using the above-mentioned comparative sample A, example sample B, and example sample C with the grinding apparatus of the type shown in FIG. Show. The symbol indicates the value when the comparative sample A is used, the symbol ◯ indicates the value when the example sample B is used, and the symbol Δ indicates the value when the example sample C is used. FIG. 20 shows the change in the surface roughness (μmRz) of the work material with respect to the number of processing. The surface roughness of any sample is not significantly different, but the comparative sample A is burned at about 40. However, in Example Sample B, no burning occurs even at about 100, and in Example Sample C, no burning occurs even at about 180, and at least the number of processing until the occurrence of burning is 2.5 times or more. . FIG. 21 shows the change in power consumption (kW) during grinding with respect to the number of workpieces. Comparative Example Sample A is slightly higher than Example Sample B and Example Sample C, but Example Sample B and Example Sample In C, the change is lower and more stable than that of Comparative Sample A. This power consumption corresponds to the sharpness, indicating that Example Sample C is sharper than Example Sample B, and Example Sample B is sharper than Comparative Sample A. FIG. 22 shows the change in the amount of wear (μm) of the wheel (vitrified grindstone) with respect to the number of machining. The sample B and the sample C are less likely to be burned than the sample A in the comparative example, and the sample sample C is not burned even if there are about 180 pieces, and even if the number of processing increases during that time, one piece The wheel wear amount per hit does not change and wears stably and shows high durability.

(Grinding test conditions)
Polishing method: Wet end polishing Work material: Steel Work material Dimensions: 70φD × 24T × 28φH (grinding width 10)
Whetstone size: 350φD × 16T × 80φH
Grinding wheel peripheral speed: 80m / sec
Stock allowance: 0.25mm

  In Example 1 described above, the vitrified bond contained in the vitrified grindstone 10 has, for example, the distribution shown in FIG. 4, that is, the average particle diameter is 3 μm, the half-value width is 1 to 8 μm, and the number of particles of 6 μm or less is 80% by number or more. Is used. In this example, as the vitrified bond, three types having an average particle size of 5 μm and a particle number ratio of 50%, 70%, and 80% of the particle size not more than twice the average particle size are prepared, The conditions other than the vitrified bond are the same as those in the preparation table C of the example sample C, and three types of vitrified grindstones, that is, the samples S1, S2, and S3, are prepared using the same process as the example of FIG. Created. Then, using these three kinds of samples S1, S2, and S3, a grinding test was performed under the same grinding test conditions as in Example 1. FIG. 24 shows changes in surface roughness (μmRz) with respect to the number of machining, FIG. 25 shows power consumption (kw) with respect to the number of machining, and FIG. 26 shows wheel wear amount R (μm) with respect to the number of machining. In FIG. 24, FIG. 25 and FIG. 26, ◇ indicates the value of the sample S1 using a vitrified bond having a particle number ratio of 50% or less than the average particle diameter, and □ indicates the average particle diameter. Indicates the value of sample S2 using a vitrified bond having a particle number ratio of 70% or less of the particle size ratio of 2 times the particle size, and Δ indicates that a vitrified bond having a particle number ratio of 80% or less of the average particle diameter of 2 times or less is used. The value of the sample S3 was shown.

  As shown in FIG. 24, the surface roughness initially shows characteristics that are small values in the order of samples S1, S2, and S3. However, as the number of processed pieces increases, the difference decreases and is not recognized. Further, with respect to the wheel wear amount R, as shown in FIG. 26, no significant difference is recognized between the samples S1, S2, and S3. However, regarding the power consumption of the electric motor that drives the grindstone, which is closely related to the sharpness of the grindstone, as shown in FIG. 25, the higher the number of particles having a diameter that is twice or less the average particle diameter, that is, the sample S1, In the order of S2 and S3, the life until the occurrence of burning becomes longer, and the power consumption is reduced and the sharpness is improved. From this, it is presumed that the finer structure of the superabrasive grains 20 is formed as the vitrified bond particles are aligned.

Next, a cylindrical comparative sample D similar to that shown in the vitrified grindstone 27 of FIG. 30 was prepared using the same steps as in the embodiment of FIG. 3 except that the materials shown in the preparation table D were used. . Next, a cylindrical example sample F and an example sample F similar to the comparative example sample D are prepared by using the same steps as in the example of FIG. 3 described above except that the materials shown in the preparation table E and the preparation table E are used. Was created respectively. In Comparative Sample D, Example Sample E, and Example Sample F, superabrasive grains (CBN abrasive grains) 20 having the same material and size are used, but in Comparative Example Sample D, inorganic hollow particles are used. The number N _s of the filler particles 22 is ½ of the number N _m of the superabrasive grains 20, and the filler particles 22 have the same particle size as the superabrasive grains 20 (# 325/400), that is, approximately the same average. It has a particle size. On the other hand, the number N _s of filler particles 22 of Example Sample E is 1 times the number N _m of superabrasive grains 20, and the filler particles 22 (# 500) are superabrasive grains 20 (# 500). # 325/400), the number N _s of filler particles 22 of Example Sample F is 5 times the number N _m of superabrasive grains 20, and The filler particles 22 (# 700) have a fine particle size, that is, an average particle size of about 1/2 that of the superabrasive particles 20 (# 325/400).

(Formulation D for Comparative Sample D)
Number of superabrasive grains N _m : Number of filler particles N _s 1: 0.5
Abrasive grain concentration: 100
Super abrasive: CBN abrasive (# 325/400) 35 parts by volume Filler particles: Inorganic hollow particles (# 325/400) 15 parts by volume Vitrified bond 20 parts by volume
Amount of paste 6 parts by volume

(Formulation E for Example Sample E)
Number of superabrasive grains N _m : number of filler particles N _s 1: 1
Abrasive grain concentration: 100
Superabrasive grain: CBN abrasive grain (# 325/400) 35 parts by volume Filler particles: inorganic hollow particles (# 500) 15 parts by volume Vitrified bond 20 parts by volume
Amount of paste 6 parts by volume

(Formulation F for Example Sample F)
Number of superabrasive grains N _m : Number of filler particles N _s 1: 5
Abrasive grain concentration: 100
Superabrasive grain: CBN abrasive grain (# 325/400) 35 parts by volume Filler particles: inorganic hollow particles (# 700) 15 parts by volume Vitrified bond 20 parts by volume
Amount of paste 6 parts by volume

  27, 28, and 29 show the cylindrical workpiece 28 under the test conditions shown below using the above-described comparative sample D, example sample E, and example sample D in the grinding apparatus of the type shown in FIG. The result of having performed the grinding test which grinds the inner peripheral surface of is shown. The symbol indicates the value when the comparative sample D is used, the symbol ◯ indicates the value when the example sample E is used, and the symbol Δ indicates the value when the example sample F is used. FIG. 27 shows the change in the surface roughness (μmRz) of the work material with respect to the number of processing. The surface roughness of Comparative Sample D is large and the rate of increase is high in the number of processing of 20. The example sample E has a lower surface roughness and a lower increase rate than the comparative sample D. In the example sample F, the surface roughness is lower than that in the example sample E, and the increase rate is low. FIG. 28 shows a change in power consumption (kW) during grinding with respect to the number of processed pieces. In the case of 20 processed pieces, the example sample E and the example sample F are lower and more stable than the comparative example sample D. Is shown. This power consumption corresponds to the sharpness, and the example sample F has better sharpness than the example sample E, and the example sample E has better sharpness than the comparative example sample D. FIG. 29 shows the change in the amount of wear (μm) of the wheel (vitrified grindstone 10) with respect to the number of machining. With 20 processed samples, Example Sample E and Example Sample F have less wear than Comparative Sample D, and no burning occurs. In Comparative Sample D, when the number of processed samples reaches 20, the abrasive grains The omission was observed.

(Grinding test conditions)
Polishing method: Wet internal polishing Work material: SUJ-2
Workpiece dimensions: 60φD × 13T × 28φH
Wheel size: 25φD × 14T × 11φH
Grinding wheel peripheral speed: 45m / sec
Trade allowance: 0.7mm

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is a perspective view which shows the shape of the vitrified grindstone of one Example of this invention. It is a figure explaining the example of grinding of the grinding device using the vitrified grindstone of FIG. It is process drawing explaining the manufacturing process of the vitrified grindstone of FIG. It is a figure which shows an example of the particle size distribution of the vitrified bond contained in the vitrified grindstone of FIG. It is a figure which shows an example of the particle size distribution of the filler particle mixed for manufacture of the vitrified grindstone of FIG. In the vitrified whetstone shown in FIG. 1, the superabrasive grains having a coarse particle size of # 325 or more and filler particles are filled with vitrified bond, and the superabrasive grains are filled as one basic unit particle number. FIG. 3 is a perspective view showing a unit structure, that is, a body-centered cubic lattice filling structure that appears three-dimensionally when the agent particle is composed of one agent particle. In the vitrified whetstone shown in FIG. 1, the superabrasive grains having a coarse particle size of # 325 or more and filler particles are filled with vitrified bond, and the superabrasive grains are filled as one basic unit particle number. FIG. 5 is a perspective view showing a unit structure that is three-dimensionally repeated when the agent particles are composed of three, that is, a face-centered cubic lattice-packed structure. In the vitrified whetstone shown in FIG. 1, the superabrasive grains having a coarse particle size of # 325 or more and filler particles are filled with vitrified bond, and the superabrasive grains are filled as one basic unit particle number. It is a perspective view which shows the unit structure which appears three-dimensionally, when it is comprised from five agent particles, ie, a hexagonal close packing structure. It is a microscope picture figure which expands and shows the surface of the comparative example sample A manufactured using the material shown to the preparation table A using the process similar to FIG. It is a microscope picture figure which expands and shows the surface of the Example sample C manufactured using the material shown to the preparation table C using the process similar to FIG. It is a figure which compares and shows distribution of the space | interval B 'of the superabrasive grain of the comparative example sample A and the Example sample C. It is a figure which shows hardness distribution by expressing the measurement result of the hardness in the surface of the comparative example sample A in three steps. It is a figure which shows hardness distribution by expressing the measurement result of the hardness in the surface of the comparative example sample A 1 mm in depth in three steps. It is a figure which shows hardness distribution by expressing the measurement result of the hardness in the surface of the comparative example sample A 2 mm in depth in three steps. It is a figure which shows hardness distribution by expressing the measurement result of the hardness in the surface of Example sample C in three steps. It is a figure which shows hardness distribution by expressing the measurement result of the hardness in the surface of the depth 1mm of Example sample C in three steps. It is a figure which shows hardness distribution by expressing the measurement result of the hardness in the surface of the depth 2mm of Example sample C in three steps. It is a figure which shows an uneven | corrugated distribution by expressing the measurement result of the unevenness | corrugation of the surface after the dressing of the comparative example sample A in three steps. It is a figure which shows an uneven | corrugated distribution by expressing the measurement result of the unevenness | corrugation of the surface after the dressing of the Example sample C in three steps. It is a figure which shows the change of the surface roughness with respect to a process number when a grinding test is done using the comparative example sample A, the example sample B, and the example sample C. It is a figure which shows the change of the power consumption with respect to the number of processes when a grinding test is done using the comparative example sample A, the example sample B, and the example sample C. It is a figure which shows the change of the amount of wheel wear with respect to a process number when a grinding test is done using the comparative example sample A, the example sample B, and the example sample C. It is a figure which shows the principal part of a structure of the grinding device which performed the grinding test using the comparative example sample A, the Example sample B, and the Example sample C. Three types of samples having the same composition as Example Sample C except that three types of vitrified bonds having a particle size of 5 μm and a particle number ratio of 50%, 70%, and 80%, which is twice or less the average particle size, were used. It is a figure which shows the surface roughness with respect to the number of processes obtained when S1, S2, and S3 were used for the grinding test. Three types of samples having the same composition as Example Sample C except that three types of vitrified bonds having a particle size of 5 μm and a particle number ratio of 50%, 70%, and 80%, which is twice or less the average particle size, were used. It is a figure which shows the power consumption with respect to the number of process obtained when S1, S2, and S3 were used for the grinding test. Three types of samples having the same composition as Example Sample C except that three types of vitrified bonds having a particle size of 5 μm and a particle number ratio of 50%, 70%, and 80%, which is twice or less the average particle size, were used. It is a figure which shows the wheel wear amount R with respect to the number of processes obtained when S1, S2, and S3 were used for the grinding test. It is a figure which shows the change of the surface roughness with respect to the number of process when a grinding test is done using the comparative example sample D, the example sample E, and the example sample F. It is a figure which shows the change of the power consumption with respect to the number of process when a grinding test is done using the comparative example sample D, the example sample E, and the example sample F. It is a figure which shows the change of the amount of wheel wear with respect to the number of processes when a grinding test is done using comparative example sample D, example sample E, and example sample F. It is a figure which shows the principal part of a structure of the grinding device which performed the grinding test using the comparative example sample D, the Example sample E, and the Example sample F.

Explanation of symbols

10: Vitrified grinding wheel (Super abrasive vitrified grinding wheel)
12: Workpiece 20: superabrasive 22: filler particles 24: vitrified G _T: unit structure (body-centered cubic lattice-like packed structure)
G _M : Unit structure (face-centered cubic lattice filling structure)
G ₆ : Unit structure (hexagonal close packed structure)

Claims (11)

Within at least some of the superabrasive grains and ultra abrasive grains against the abrasive stone tissue and filler particles Ru formed are joined by molten glass having an average particle diameter of 0.5 to 1.5 times, the greater abrasives and unit structure sterically repeated filler particles as a reference, ultra the filler particles that consists of 1.0 to 5.0 atoms for one superabrasive as a basic unit the number of particles A method for producing an abrasive vitrified wheel ,
A superabrasive bond coating step in which a coating made of a vitrified bond and a binder having an average particle size of 1/10 or less of the superabrasive grain is formed on the outer surface of the superabrasive grain in a layered manner;
A filler particle bond coating step in which a coating composed of the vitrified bond and a binder is formed in a layer on the outer surface of the filler particles;
Superabrasive grains in which the coating is layered on the outer surface in the superabrasive bond coating step and filler particles in which the coating is layered on the outer surface in the filler particle bond coating step A mixing step of mixing;
A molding step of molding a predetermined molded product by filling and pressing the mixed material uniformly mixed in the mixing step into a molding space in the press mold, and
A firing step of obtaining a superabrasive vitrified grindstone having the grindstone structure by melting the vitrified bond at the same time as the viscous binder disappears by firing the molded product formed in the forming step.
The manufacturing method of the superabrasive vitrified grindstone characterized by including these. 2. The superabrasive vitrified grinding wheel according to claim 1, wherein the unit structure forms a body-centered cubic lattice-like filling structure including one superabrasive grain and one filler particle. 3 . Production method. In the filling structure of the body-centered cubic lattice, one superabrasive grain is bound by the molten glass body in a state of being spatially surrounded by the filler particles located at the eight nearest positions. The method for producing a superabrasive vitrified grindstone according to claim 2 . 2. The superabrasive vitrified grinding wheel according to claim 1, wherein the unit structure has a face-centered cubic lattice-like filling structure including one superabrasive grain and three filler particles. 3 . Production method. In the face-centered cubic lattice-shaped filling structure, one superabrasive grain is bound by the molten glass body in a state of being spatially surrounded by the filler particles located at the 12 nearest positions. The method for producing a superabrasive vitrified grindstone according to claim 4 . The method for producing a superabrasive vitrified grindstone according to claim 1, wherein the unit structure forms a six-way finely packed structure including one superabrasive grain and five filler particles . In the hexagonal close-packed structure, one superabrasive grain is formed by the molten glass body in a state of being spatially surrounded by the filler particles located at the 12 positions of the nearest neighbor position and the second closest position. The method for producing a superabrasive vitrified grindstone according to claim 6, wherein the grindstone is bonded . The method for producing a superabrasive vitrified grindstone according to any one of claims 1 to 7, wherein a center value of grindstone hardness occupies a region of 90% or more of the entire surface on the surface of the grindstone structure . The method for producing a superabrasive vitrified grindstone according to any one of claims 1 to 8, wherein the superabrasive grain has a grain size coarser than # 325 . The production of the superabrasive vitrified grindstone according to any one of claims 1 to 9, wherein the filler particles have a particle size distribution in which the number in the range of ± 15% centered on the center particle size occupies 90% or more. Method. The method for producing a superabrasive vitrified grindstone according to any one of claims 1 to 10, wherein the superabrasive grains are diamond abrasive grains or CBN abrasive grains, and the filler particles are inorganic hollow particles .

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