TW201943500A - Vitrified grindstone having rough-textured homogeneous structure - Google Patents

Abstract

Provided is a vitrified grindstone having a rough-textured (porous) homogeneous structure, the vitrified grindstone being capable of grinding even hard-to-cut materials without generating a burn and while retaining shape-maintenance properties. According to this vitrified grindstone having a rough-textured homogeneous structure, abrasive grains fill the vitrified grindstone at a proportion of 23-35 vol% together with an inorganic hollow filler, the abrasive grains being homogeneous so as to have a standard deviation [sigma] of 8.7 or less in a frequency distribution map of abrasive grain area, which is a proportion of solids including the abrasive grains per unit area at a plurality of locations in a cross-section of the vitrified grindstone. This results in high homogeneity in a grindstone structure and maintains shape-maintenance properties (reduction in the amount of wear of the grindstone) even with respect to a rough texture having a low volume ratio of abrasive grains, and therefore the generation of burns in a to-be-cut material is suppressed while shape-maintenance properties are maintained even with respect to hard-to-cut materials.

Description

Vitrified grinding stone with coarse structure and homogeneous structure

The invention relates to a vitrified grindstone with a low abrasive grain volume ratio and a porous structure with a coarse structure and a homogeneous structure.

2. Description of the Related Art High-porosity vitrified grinding stones are generally known as grinding stones suitable for applications in areas where the grinding load of internal surface grinding, corner grinding, and the like is high, and workpieces are liable to be burnt and burnt. For example, the CBN vitrified grinding stone with a high porosity described in Patent Document 1 is an example. With such a high porosity vitrified grindstone, because the pores are artificially formed by the pore-forming material to become a high porosity, it is easy to release the grinding heat during the grinding process under the grinding liquid, and it can appropriately suppress the grinding and scorching of the workpiece. .

However, in the case of grinding of turbine blades or bearing grooves, the grinding process that is easy to be flattened due to the shape of the grinding stone or the grinding, or the grinding process where the heat conductivity of the workpiece is low and the heat during the process is not easy to escape, even It is the above-mentioned high porosity vitrified grinding stone, which still has problems such as burnt or faster shape wear.

In addition, if the processing resistance is to be reduced by reducing the abrasive grain ratio, in order to maintain a large abrasive grain interval, as a result, it becomes a coarse-structured vitrified grindstone forming an atmospheric pore. The above-mentioned prior art has the disadvantage that the structure of the grindstone is liable to become heterogeneous due to the formation of atmospheric pores. In addition, if an organic pore-forming material that can be burned during firing of a grindstone is used to form pores, there is also a disadvantage that when the abrasive particles are rearranged due to firing shrinkage, abrasive particle aggregation is liable to occur.

Prior Art Literature Patent Literature Patent Literature 1: Patent No. 3987719 Patent Literature 2: Patent No. 6013133

SUMMARY OF THE INVENTION In contrast to the problems to be solved by the invention, in Patent Document 2, a uniform grindstone structure is formed by forming pores using alumina hollow particles, thereby increasing the contact ratio between abrasive grains and the volume ratio of abrasive grains. Reduced to a certain degree of low abrasive grain rate, porosity and homogeneous structure of vitrified grinding stone. With this, it is possible to suppress the agglomeration of abrasive grains when the abrasive grains are rearranged due to firing shrinkage, and it is possible to suppress the occurrence of abrasive burn and shape wear.

However, even when the vitrified grindstone described in the above Patent Document 2 is used to grind difficult-to-grind materials such as INCONEL (registered trademark), Haynes (registered trademark) of Haynes, stainless steel, titanium alloy, etc., depending on the polishing conditions, There is a case where the reduction of the shape retention (abrasion of the grindstone) cannot be completely solved or the burnt burnt, and there are problems regarding the quality of the grindstone and the life of the grindstone.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a vitrified mill having a homogeneous structure of a coarse structure (porous) that can be polished while maintaining shape retention even if it is a difficult-to-grind material. stone.

In view of the foregoing, the present inventors, in view of the fact that the volume maintainability of the abrasive grain volume ratio of less than 40% by volume of the porosity and coarse structure of the vitrified grindstone is not reduced, and the scorch of the abrasive material is suppressed. Various studies have been conducted on the rate and the homogeneity of the grindstone structure. As a result, it has been found that even if the inorganic hollow filler is used to form a low abrasive grain volume ratio that was previously considered to be unable to obtain shape retention, as long as the grindstone structure is improved, Homogeneity can maintain shape retention (reduction in the amount of abrasive wear), and it is possible to obtain the effect of suppressing grinding and scoring even with difficult-to-grind materials. The present invention has been completed based on the above findings. The inventors speculated that if the volume ratio of the abrasive particles is reduced to promote the dispersion of the inorganic hollow fillers filled in a specific range with respect to the volume ratio of the abrasive particles, a homogeneous structure in which the abrasive particles and the inorganic hollow fillers are close to each other can be obtained. Therefore, while maintaining the shape maintaining property, the scorch of the material to be polished can be appropriately suppressed.

The means to solve the problem is the vitrified grinding stone of the coarse structure homogeneous structure of the first invention, which aims at: the vitrified grinding of the coarse structure homogeneous structure of the abrasive grains and the inorganic hollow filler combined with the inorganic binder Stone, the abrasive grains are filled with a volume ratio of 23 to 35 vol%, and the vitrified grinding stone has homogeneity, which has a standard deviation of 10 or less in the frequency distribution diagram of the abrasive grain area ratio. The abrasive grain area ratio is the ratio of the solid content including the aforementioned abrasive grains per unit area at a plurality of positions in the section of the vitrified grindstone.

The main point of the second invention is that in the first invention, the inorganic hollow filler has an average particle diameter of 1.6 times or less with respect to the abrasive particles.

The main point of the third invention is that in the first invention or the second invention, the inorganic hollow filler is filled with a volume ratio of 0.2 to 1.7 times the volume ratio of the abrasive grains.

The main point of the fourth invention is that in any one of the first to third inventions, the inorganic binder is mixed at a volume ratio of 10 to 15 vol%.

The main object of the fifth invention is to provide homogeneity in any one of the first to fourth inventions, and the homogeneity has a standard deviation of 6.5 to 8.7 in the frequency distribution chart of the area ratio of the abrasive grains.

The main point of the sixth invention is that in any one of the first to fifth inventions, the inorganic hollow filler is filled at a ratio of 4 to 45 vol%.

The main object of the seventh invention is that in any one of the first to sixth inventions, the inorganic hollow filler has an average particle diameter of 0.6 to 1.6 times the abrasive grains.

The main object of the eighth invention is that in any one of the first to seventh inventions, the inorganic hollow filler has a volume ratio of 0.2 to 1.67 times the volume ratio of the abrasive particles.

The main object of the ninth invention is that in any one of the first to seventh inventions, the abrasive particles are alumina-based abrasive materials or silicon carbide abrasive materials, and the particle sizes of the abrasive particles are F80 to F120.

ADVANTAGE OF THE INVENTION According to the 1st invention, the vitrified grindstone-type abrasive grain of a coarse structure homogeneous structure, and an inorganic hollow filler are combined with an inorganic binder, The said abrasive grain is filled in the ratio of 23-35 vol%, and the said vitrification The grinding stone has homogeneity with a standard deviation of 8.5 or less in the frequency distribution diagram of the area ratio of the abrasive grains. The area ratio of the abrasive grains is the solid content of the solid matter including the foregoing abrasive grains per unit area at a plurality of positions in the section of the vitrified grinding stone. ratio. Therefore, even if the volume ratio of the abrasive grains is low, the structure of the grindstone is still high and the shape maintainability can be maintained (the amount of grinding stone wear is reduced). Therefore, it is possible to maintain the shape maintainability even for difficult-to-abrasive materials while suppressing the The abrasive material is burnt.

According to the second invention, the inorganic hollow filler has an average particle diameter of 1.6 times or less with respect to the abrasive particles. Therefore, a vitrified grindstone having a porous structure and a homogeneous structure having a grindstone structure having a high homogeneity can be obtained.

According to the third invention, the inorganic hollow filler is filled at a volume ratio of 0.2 to 1.7 times the volume ratio of the abrasive particles. Therefore, a vitrified grindstone having a porous structure and a homogeneous structure having a grindstone structure having a high homogeneity can be obtained.

According to the fourth invention, the inorganic binder is mixed at a volume ratio of 10 to 15 vol%. Therefore, a vitrified grindstone with a high porosity and a homogeneous structure can be obtained.

According to the fifth invention, it is provided with homogeneity having a standard deviation of 6.5 to 8.7 in the frequency distribution chart of the area ratio of the abrasive grains. Thereby, even if the volume ratio of the abrasive grains is low, the shape maintaining property with a high homogeneity of the grindstone structure can be maintained (abrasion amount of the grindstone is reduced).

According to the sixth invention, the inorganic hollow filler is filled at a ratio of 4 to 45 vol%. Therefore, it is possible to obtain a vitrified grinding stone having a low abrasive grain volume ratio and a large number of pores.

According to the seventh invention, the inorganic hollow filler has an average particle diameter of 0.6 to 1.6 times the abrasive grains. Therefore, it is possible to obtain a vitrified grinding stone having a low abrasive grain volume ratio and a large number of pores.

According to the eighth invention, the inorganic hollow filler has a volume ratio of 0.2 to 1.67 times the volume ratio of the abrasive particles. Therefore, it is possible to obtain a vitrified grinding stone having a low abrasive grain volume ratio and a large number of pores.

The main object of the ninth invention is that in any one of the first to seventh inventions, the abrasive particles are alumina-based abrasive materials or silicon carbide abrasive materials, and the particle sizes of the abrasive particles are F80 to F120. Thereby, a hard abrasive material can be grind | polished without using the general abrasive grains and the scorch accompanying grinding | polishing.

Form for Carrying Out the Invention In one form for carrying out the invention, the aforementioned inorganic hollow fillers are preferably volcanic ash hollow particles (SHIRASU BALLOON), alumina hollow particles, mullite hollow particles, glass hollow particles, and the like.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In addition, in the following embodiments, the drawings are appropriately simplified or conceptualized, and the dimensional ratios, shapes, and the like of each part are not necessarily accurately drawn.

FIG. 1 shows an example of a vitrified grindstone 10 having a high porosity vitrified grindstone having a porous and homogeneous structure according to an embodiment of the present invention. The vitrified grindstone 10 is formed in a disc shape as a whole, and is driven to rotate about the axis C in a state where the vitrified grindstone 10 is mounted on the main shaft of the polishing disc by using a mounting hole 12 formed in a central portion thereof. The material 16 to be polished is slidably contacted with the tapered outer peripheral polishing surface 14 of the vitrified grindstone 10.

FIG. 2 shows how the corners 18 of a rectangular parallelepiped material 16 made of a heat-resistant alloy such as INCONEL (registered trademark) are polished. In the state where the vitrified grinding stone 10 is rotated, while pressing the corner of the cuboid-shaped abrasive material 16 against the outer peripheral grinding surface 14 of the vitrified grinding stone 10, the abrasive material 16 is oriented in the length direction, that is, as shown in FIG. 2 The paper surface is conveyed in a vertical direction, thereby grinding the corner 18 of the material 16 to be ground.

FIG. 4 is a schematic diagram illustrating the structure of the vitrified grindstone 10 on an enlarged scale. In FIG. 4, for example, abrasive grains 20 composed of general abrasive grains such as alumina abrasive materials or silicon carbide abrasive materials, and, for example, volcanic ash hollow particles, alumina hollow particles, mullite hollow particles, and glass hollow particles The inorganic hollow fillers 22 having the same structure are bonded to each other by melting the vitrified bonding material 24 of the glassy inorganic bonding agent. Between the abrasive grains 20, the inorganic hollow filler 22, and the vitrified bonding material 24, pores 26 formed naturally due to the disappearance of a binder (forming aid) or the like in a manufacturing step are formed.

The abrasive grain 20 is filled with an abrasive grain volume ratio of 23 to 35 vol% and has homogeneity. The homogeneity is a standard deviation of 8.5 or less in the frequency distribution diagram of the abrasive grain area rate. The abrasive grain area rate is vitrified The ratio of the solid content including the abrasive grains 20 per unit area at the plural positions in the cross section of the grindstone 10. In this way, the vitrified grinding stone 10 has a very low abrasive grain volume ratio, but maintains the shape maintenance of the grinding stone by the homogeneity of the grinding stone structure. It is a vitrified grinding stone with a porous structure and a homogeneous structure.

In the vitrified grindstone 10, the inorganic hollow filler 22 is filled at a filler volume ratio of 0.2 to 1.7 times the volume ratio of the abrasive particles. The inorganic hollow filler 22 is filled at a ratio of 4 to 45 vol%. The inorganic hollow filler 22 has an average particle diameter of 1.6 times or less with respect to the average particle diameter of the abrasive grains 20, and preferably has an average particle diameter in the range of 0.6 to 1.4 times. In addition, the inorganic hollow filler 22 has a volume ratio in the vitrified grindstone 10 of 0.2 to 1.67 times, and preferably 0.43 to 1.4 times the volume of the abrasive grains 20.

In the vitrified grinding stone 10, a vitrified bonding material (inorganic bonding agent) 24 is mixed at a volume ratio of 10 to 15 vol%.

With such a composition, the vitrified grindstone 10 is provided with a homogeneity having a standard deviation of 10 or less, preferably 6.5 to 8.5 in the frequency distribution diagram of the abrasive grain area ratio, and the abrasive grain area ratio is a plural position in the grindstone section. The ratio of solids including abrasive particles 20 per unit area.

The vitrified grindstone 10 is manufactured, for example, according to the step diagram shown in FIG. 3. That is, in the abrasive grain bonding coating step P1, the abrasive grains 20 and the powdery vitrified bonding material 24 are mixed together with a binder (forming aid). The vitrified bonding material 24 is a semi-melted material after melting. Glass powder with high impact resistance and excellent heat resistance, for example, has an average particle size of less than 1/10 of the abrasive grains 20, and the binder is a well-known synthetic paste such as dextrin. A coating layer composed of the vitrified bonding material (inorganic bonding agent) 24 and a bonding agent is formed in a layered manner on the outer surface of the abrasive particles 20, and if necessary, it is dried to impart stronger fluidity. In the filler particle-bonded coating step P2, an inorganic hollow filler 22 composed of, for example, mullite hollow particles and the like is also mixed with the above-mentioned same vitrified bonding material 24 and a well-known binder such as dextrin, thereby A coating layer composed of the vitrified bonding material 24 and a binder is formed in a layered manner on the outer peripheral surface of the inorganic hollow filler 22, and is dried as necessary to impart stronger fluidity.

The vitrified bonding material 24 is a glass powder having high impact resistance and heat resistance. For example, the oxide composition is SiO ₂ 50 to 80% by weight, B ₂ O ₃ 10 to 20% by weight, and Al ₂ O ₃ 5 to 15% by weight. %, Glass semi-melt with a total of 8-15% by weight of metal oxides selected from CaO, MgO, K ₂ O, and Na ₂ O, or 70-90% by weight SiO ₂ , B 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 of glass semi-melt, etc., that is, powder glass that is semi-melted after melting. In addition, the vitrified bonding material 24 may be added with clay or the like to the powder glass. The vitrified bonding material 24 is preferably angular particles obtained by wet pulverization, and has a monomer volume ratio of 55 vol% or more when a molding pressure of 300 kg / mm ² is applied. A table obtained by measurement according to the ASTM D2840 standard. The apparent density (body specific gravity) is 1.2 or more.

The abrasive particles 20 are, for example, those having a particle size in the range of F80 to F120, for example, a particle size in the range of an average particle diameter of about 180 μm to 106 μm, and are filled at a ratio of 23 to 35 vol%.

Inorganic hollow filler 22 includes, for example, based 0.5 ~ 1.0g / cm ³ of apparent density, 0.25 ~ 0.45g / cm ³ of density, 70N / mm ² of the compressive strength, above the melting point of 1200 deg.] C, water absorption of the substantially zero Closed hollow particles.

The inorganic hollow filler 22 is a filler volume ratio of 0.4 to 1.7 times the volume ratio of the abrasive particles relative to the abrasive particles 20, a volume ratio of 15 to 45 vol%, and a volume of 0.43 to 1.67 times the volume of the abrasive particles 20. Volume ratio modulation.

Next, in the mixing step P3, the abrasive grains 20 and the inorganic hollow fillers 22 respectively coated with the above-mentioned coatings are put into a mixer together with a well-known binder such as dextrin, and uniformly mixed in the mixer. Next, in the molding step P4, the above-mentioned mixed material is filled in a specific stamper for forming a cylindrical molding space, and the molding is performed by pressing with a press. In the firing step P5, the molded product that has undergone the shaping step P4 is sintered in a specific firing furnace under firing conditions that are held at a temperature of about 900 ° C. for 0.5 hours, for example. By this sintering, since the bonding agent is burned off and the vitrified bonding material 24 is melted to become a molten glass body, as shown in the structure chart of the vitrified grindstone of FIG. 4, the abrasive particles 20 and the inorganic hollow filler 22 pass through the molten glass. The bonding materials 24 are bonded to each other to form a vitrified grindstone 10. Next, in the final processing step P6, the outer peripheral surface and the end surface are mechanically final processed with a cutting or grinding tool in such a way that the outer dimensions become predetermined product specifications, thereby manufacturing the aforementioned vitrified grindstone 10, and after the inspection step P7, Ship.

According to the vitrified grindstone 10 having the grindstone structure shown in FIG. 4 manufactured as described above, a vitrified grindstone structure is formed, and the vitrified grindstone structure is an abrasive grain that is relatively helpful to the grinding performance. 20 and the inorganic hollow filler 22 constituting a grindstone structure together with the abrasive grains 20 are formed by uniformly filling a specific space with the vitrified bonding material 24, and the abrasive grains 20 and the inorganic hollow filler 22 are prepared by the aforementioned formulation. It becomes homogeneous, and a more homogeneous distance is formed between the abrasive grains 20 via the inorganic hollow filler 22, so that grinding and scoring are less likely to occur and a longer grinding stone life can be obtained. In addition, since the abrasive particles 20 and the inorganic hollow filler 22 are homogeneously dispersed, and are bonded to each other by the vitrified bonding material 24 in a state of being in contact with or close to each other, the shape maintaining property can be improved.

In order to evaluate the change in the volume ratio of abrasive grains and the material of the pore forming material, the change in the particle size of the abrasive grains, and the change in the volume ratio of the inorganic hollow filler in the grinding stone structure of the vitrified grindstone 10, the present inventors etc. For the dispersibility, the homogeneity evaluation test 1, the homogeneity evaluation test 2, and the homogeneity evaluation test 3 shown below were performed. In these experiments, different compositions were used to make the same steps as shown in FIG. 3, and other cross-sectional images were taken with a digital microscope, and the binarized black-and-white cross-sectional images obtained from the cross-sectional images were segmented. , Calculate the area of the solids in the white part at each of the multiple divided (unit) regions, and make a frequency distribution chart with the area ratio as the horizontal axis and the cumulative number of the divided regions as the vertical axis, and use the value indicating the dispersed state The standard deviation σ of the frequency distribution chart is calculated in the form, and an evaluation test of homogeneity is performed using the standard deviation σ. In addition, one side x of the divided region is, for example, a function (x = (500πD ² / 4Vg) ^0.5 ) of the average particle diameter D of the abrasive grains and the abrasive grain accumulation rate Vg. The smaller the standard deviation σ, the higher the homogeneity of the grindstone structure of the vitrified grindstone 10.

(Homogeneity evaluation test 1)
In order to evaluate the homogeneity of the vitrified grindstone when the volume ratio of the abrasive grains and the material of the inorganic hollow filler are changed, abrasive grains having a particle size F100 of Alundum (registered trademark), which is a representative type of alumina-based abrasive grains, are prepared to obtain the abrasive grain volume. The rate of 23%, 27%, 31%, 35% (equivalent to the low abrasion rate of the tissues 20, 18, 16, 14), that is, the coarse structure, is mixed with the stomata forming material, and the vitrification made by the same steps as in FIG. 3 is used. The Example 1 to Example 4 and Comparative Example 1 to Comparative Example 3 of the grindstone test pieces were measured for the standard deviation σ from the cross-sectional images of the test pieces as described above. FIG. 5 shows the composition and standard deviation σ of the test pieces, and FIG. 6 shows the results of the evaluation. In Example Product 1 to Example 4, mullite hollow particles (inorganic hollow fillers) having an average particle diameter of 125 μm were used as the pore-forming material. On the other hand, in Comparative Example Product 1 to Comparative Example Product 3, an organic pore forming material having an average particle diameter of 250 μm was used as the pore forming material. If the organic pore forming material having an average particle diameter of 125 μm is used in Comparative Example 1 to Comparative Example 3, since there are fewer contact points between the abrasive grains, the shrinkage during firing will be large, and it will become the starting point of grinding stone failure. In order to avoid such cracks, an organic pore forming material having an average particle diameter of 250 μm is used. In addition, although not shown in FIG. 5, the glass transition bonding material is filled with a mutually fixed ratio in the range of 10 to 15 vol%. As shown in Fig. 5 and Fig. 6, in the low abrasive particle volume ratio of 27 to 35 vol%, Comparative Example 1 to Comparative Example 3 using organic pore forming materials have relatively large firing shrinkage and become homogeneous. Standard The deviation σ is 10 or more. In contrast, in Examples 1 to 4 using inorganic hollow fillers, the firing shrinkage is relatively small, and the interval between abrasive particles can be maintained. The standard deviation σ is less than 10 and is 7.6 to 8.4.

(Homogeneity evaluation test 2)
In the range of particle sizes F80 to F120 of Alundum (registered trademark), which is a representative alumina-based abrasive grain used for grinding or groove processing of difficult-to-abrasive materials, the same steps as in FIG. 3 were used to prepare a low abrasive grain volume ratio ( Coarse texture) vitrified grindstone test piece (example product 2, example product 5 to example product 10) corresponding to tissue 16 (abrasive grain volume ratio 31%), in order to evaluate the homogeneity of these, The cross-sectional images of the test pieces were each measured for the standard deviation σ as described above. FIG. 7 shows the composition and standard deviation σ of the test pieces, and FIG. 8 shows the results of the evaluation. As shown in FIG. 7 and FIG. 8, the standard deviation σ is 10 or less, and specifically 6.8 to 9.4, in the particle size ratio (= porosity forming material / particle size) of the pore forming material to the abrasive grains of 0.6 to 1.6 times. . Fig. 8 shows a tendency that, regardless of the particle size of the abrasive particles, the smaller the particle diameter ratio (= pore-forming material / particle diameter) of the inorganic hollow filler (hollow particles of mullite) to the abrasive particles, the smaller the standard deviation σ.

(Homogeneity evaluation test 3)
Structures corresponding to low abrasive grain volume ratio (coarse texture) of Alundum (registered trademark) particle size F100 using representative alumina-based abrasive grains for grinding or groove processing of difficult-to-abrasive materials 14, 16, 18 In 19, 19 (abrasive particle volume ratios of 35%, 31%, 27%, and 26%), the steps shown in FIG. 3 were used to produce Example Products 1 to 3 that change the volume ratio of the inorganic hollow filler as shown in FIG. 9. In Examples 11 to 21, in order to evaluate their homogeneity, the standard deviation σ was measured from the cross-sectional images of these test pieces as described above. FIG. 9 shows the composition and standard deviation σ of the test pieces, and FIG. 10 shows the evaluation results of the test pieces. As shown in Figures 9 and 10, the volume ratio of the inorganic hollow filler (hollow particles of mullite) to the abrasive particles is 0.43 regardless of any of the abrasive particle volume ratios of 35%, 31%, 27%, and 26%. In the range of ~ 1.67, the standard deviation σ is 8.5 or less. Figure 10 shows the hyperbola-like tendency characteristics. In the low abrasive grain volume ratio (abrasive grain volume ratio 35%, 31%, 27%, 26%), regardless of the abrasive grain volume ratio, the inorganic hollow filler relative to the abrasive grain The lower the volume ratio, the more the standard deviation σ increases. In the linear shape of this tendency characteristic, even if the volume ratio of the inorganic hollow filler to the abrasive particles is 0.35, a standard deviation σ of 10 or less is obtained.

Next, the present inventors used the procedure shown in FIG. 3 to prepare Comparative Example 4 and Structure 14 (Grit Volume Ratio) of Microstructure 12 (Grit Volume Ratio 39%) using Alundum (registered trademark) abrasive grain size F80. 35%) of Comparative Examples 5, 6 and Example 22, in order to evaluate their homogeneity, σ was measured from the cross-sectional images of these test pieces as described above. In Comparative Examples 5, 6 and Example 22, the standard deviation σ is different because of the change in the volume ratio of the vitrified bonding material. FIG. 11 shows the composition and standard deviation σ of the test pieces. The standard deviations σ of Comparative Examples 4, 5, and 6 were 8.8, 11.3, and 10.6, while the standard deviations σ of Example 22 were 9.8 or less.

Next, the present inventors used the test pieces (Comparative Example Product 4, Comparative Example Product 5, Comparative Example Product 6, and Example Product 22) shown in FIG. 11 to perform the wet grinding test of FIG. 2 under the following conditions, for example .
(Polishing test conditions)
Grinding disc: Flat grinding disc Grinding method: Wet-type speed-speed material to be ground: INCONEL (registered trademark of SPECIAL METALS)
Platform conveying speed: average 20m / min
Cutting capacity: 5.5mm / min
Grinding stone size: 255 × 19 × 76.2 (mm)
Cutting fluid: water-soluble abrasive, grinding stone, peripheral speed: 45m / sec

FIG. 12 is a graph showing the grinding results of Comparative Example 4 and Example 22, that is, the grinding stone abrasion volume ratio (%) when Comparative Example 4 is set to 100%. The grinding stone abrasion volume indicates the shape maintenance of the vitrified grinding stone. As can be seen from FIG. 12, the product of Example 22 is superior to the product of Comparative Example 4 having the same homogeneity (standard deviation of 10 or less) because of the poor structure of the grindstone.

FIG. 13 is a graph showing the grinding results of Comparative Example Product 5, Comparative Example Product 6 and Example Product 22, that is, the grinding stone abrasion volume ratio (%) when Comparative Example Product 5 was set to 100%. As can be seen from FIG. 13, the product of Example 22 is superior to the product of Comparative Example 4 having the same structure (abrasive particle volume ratio) because of the homogeneity of the grindstone and the shape maintenance property.

FIG. 14, FIG. 15, FIG. 16, and FIG. 17 respectively show photographs of the burnt state of the above-mentioned material to be ground after the grinding test of Comparative Example 4, Comparative Example 5, Comparative Example 6, and Example 22, respectively. In each photo, the white part indicates burnt. As shown in FIG. 14, FIG. 15, FIG. 16, and FIG. 17, the product of Example 22 has the least scorch, and the products of Comparative Example 6 and Product 5 are sequentially burned. This also means that even if the structure (abrasive particle volume ratio) is the same, the lower the homogeneity of the grindstone, the larger the standard deviation, and the larger the scorch. In addition, the scorch of Example 22 was less than that of Comparative Example 4 by polishing. This means that even if the standard deviation is the same homogeneity of 10 or less, it is because of the difference in the structure, that is, the smaller the abrasive grain volume ratio, the less the scorch.

As described above, according to the vitrified grinding stone 10 of the coarse structure homogeneous structure of this embodiment, the abrasive grains 20 are filled at a ratio of 23 to 35 vol%, and the vitrified grinding stone is provided in the frequency distribution diagram of the abrasive grain area ratio. Homogeneity with a standard deviation σ of 8.5 or less. The abrasive grain area ratio is the ratio of the solid content of the abrasive grains per unit area at a plurality of positions in the cross section of the vitrified grindstone 10. As a result, even with a coarse structure with a low abrasive grain volume ratio, the grindstone structure has high homogeneity and maintains shape retention (reduction in grinding stone wear), so it is possible to maintain shape retention even for difficult-to-abrasive materials. On the one hand, the burnt material is suppressed from being burnt.

In addition, according to the vitrified grindstone 10 of the coarse structure homogeneous structure of this embodiment, the inorganic hollow filler 22 has an average particle diameter of 1.6 times or less with respect to the abrasive grains 20. Therefore, it is possible to obtain a vitrified grindstone 10 having a coarse structure homogeneous structure having a high porosity and a grindstone structure having a high homogeneity.

According to the vitrified grindstone 10 of the coarse structure homogeneous structure of this embodiment, the inorganic hollow filler 22 is filled with a filler volume ratio of 0.4 to 1.7 times the volume ratio of the abrasive particles. Therefore, it is possible to obtain a vitrified grindstone 10 having a coarse structure homogeneous structure having a high porosity and a grindstone structure having a high homogeneity.

According to the vitrified grindstone 10 of the coarse structure homogeneous structure in this embodiment, the vitrified bonding material (inorganic bonding agent) 24 is mixed at a volume ratio of 10 to 15 vol%. Thus, a vitrified grindstone 10 having a coarse structure and a homogeneous structure with a high porosity can be obtained.

The vitrified grindstone 10 having a homogeneous structure with a coarse structure according to this embodiment has homogeneity having a standard deviation of 6.5 to 8.5 in the frequency distribution diagram of the area ratio of the abrasive grains. Thereby, even if the volume ratio of the abrasive grains is low, the shape maintaining property with a high homogeneity of the grindstone structure can be maintained (abrasion amount of the grindstone is reduced).

According to the vitrified grinding stone 10 of the coarse structure homogeneous structure of this embodiment, since the inorganic hollow filler 22 is filled at a ratio of 15 to 45 vol%, the vitrification of the coarse structure homogeneous structure of the low abrasive grain volume rate and high porosity can be obtained. Millstone.

According to the vitrified grinding stone 10 of the coarse structure homogeneous structure of this embodiment, since the inorganic hollow filler 22 has an average particle diameter of 0.6 to 1.6 times that of the abrasive particle 20, a low abrasive particle volume ratio and a high porosity can be obtained. Vitrified grinding stone with coarse structure and homogeneous structure.

According to the vitrified grinding stone 10 of the coarse structure homogeneous structure of this embodiment, the inorganic hollow filler 22 has a volume ratio of 0.43 to 1.67 times the volume ratio of the abrasive particles 20, so a low abrasive particle volume ratio and a high porosity can be obtained. Vitrified grinding stone with coarse structure and homogeneous structure.

According to the vitrified grinding stone 10 of the coarse structure homogeneous structure in this embodiment, the abrasive grains 20 are alumina abrasive materials or silicon carbide abrasive materials, and the grain sizes of the 20 abrasive grains are F80 to F120. With this, even if the material to be polished is a difficult-to-abrasive material, ordinary abrasive particles can be used to grind the difficult-to-abrasive material without being accompanied by polishing scorch.

In the above, an embodiment of the present invention has been described based on the drawings, but the present invention can also be applied to other aspects.

For example, although the vitrified grindstone 10 of the foregoing embodiment has a disc shape as shown in FIG. 1, for example, it may have other shapes such as a cup shape or a block shape.

The above description is only one embodiment. Although other embodiments are not exemplified, the present invention can be implemented with various changes and improvements based on the knowledge of those involved in the technology without departing from the spirit thereof.

10‧‧‧ vitrified millstone

12‧‧‧Mounting holes

14‧‧‧ peripheral polished surface

16‧‧‧ Abrasive material

18‧‧‧ corner

20‧‧‧ abrasive grain

22‧‧‧Inorganic hollow filler

24‧‧‧Vitrified bonding material (inorganic bonding agent)

26‧‧‧ Stomata

P1‧‧‧step

P2‧‧‧step

P3‧‧‧step

P4‧‧‧step

P5‧‧‧step

P6‧‧‧step

P7‧‧‧step

FIG. 1 is a front view of a vitrified grindstone with a porous structure and a homogeneous structure according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a polishing example using a polishing apparatus using the vitrified grindstone of FIG. 1. FIG.

FIG. 3 is a step diagram illustrating an important part of the manufacturing method of the vitrified grindstone of FIG. 1. FIG.

FIG. 4 is an enlarged schematic view illustrating the coarse structure of the vitrified grindstone of FIG. 1.

FIG. 5 shows a plurality of test pieces obtained by changing the composition of the vitrified grindstone of FIG. 1 to confirm the relationship between the volume ratio of the abrasive grains and the homogeneity of the grindstone structure (Examples 1-4, Comparative Examples). 1-3) A graph showing the composition and the standard deviation of the homogeneity of the grindstone composition.

Fig. 6 is a graph showing the two-dimensional coordinates of the test result of Fig. 5 on the horizontal axis representing the volume ratio of the abrasive grains and the vertical axis representing the standard deviation of the homogeneity of the grindstone composition.

FIG. 7 shows the relationship between the particle size ratio of the inorganic hollow filler with respect to the abrasive grains and the homogeneity of the grindstone composition, and shows a plurality of test pieces obtained by changing the composition of the vitrified grindstone of FIG. 1 (Example Figures 2 and 5-10) are graphs showing the standard deviation of the homogeneity of the grindstone composition.

FIG. 8 is a graph showing the two-dimensional coordinates of the test result of FIG. 7 on the horizontal axis showing the particle diameter ratio of the inorganic hollow filler with respect to the abrasive grains and the vertical axis showing the standard deviation of the homogeneity of the grindstone composition.

FIG. 9 shows a plurality of test pieces obtained by changing the composition of the vitrified grindstone of FIG. 1 to verify the relationship between the volume ratio of the inorganic hollow filler with respect to the abrasive grains and the homogeneity of the grindstone structure. 1-3, 11-21) and the graph showing the standard deviation of the homogeneity of the grindstone composition.

FIG. 10 is a graph showing the two-dimensional coordinates of the test result of FIG. 9 on the horizontal axis showing the volume ratio of the inorganic hollow filler with respect to the abrasive grains and the vertical axis showing the standard deviation of the homogeneity of the grindstone composition.

FIG. 11 shows the abrasive grain volume ratio and the homogeneity (standard deviation) of the abrasive stone test pieces prepared to evaluate the abrasive wear amount corresponding to the shape maintenance property, that is, Comparative Example 4-6 and Example 22 ).

FIG. 12 is a graph showing the grinding stone abrasion amount of Comparative Example 4 and Example 22 of Comparative Example 4 and Example 22 having a large difference in volume ratio of abrasive grains.

FIG. 13 is a graph showing the grinding stone abrasion amount of Comparative Example Product 5, Comparative Example Product 6 and Example Product 22 in which the difference in homogeneity is relatively large in FIG. 11.

FIG. 14 is a photograph showing a burnt state of a material to be ground in a grinding test of Comparative Example 4 of FIG. 11.

FIG. 15 is a photograph showing a burnt state of a material to be ground in a grinding test of Comparative Example 5 of FIG. 11.

FIG. 16 is a photograph showing a burnt state of a material to be ground in a grinding test of Comparative Example 6 of FIG. 11.

FIG. 17 is a photograph showing a scorched state of a material to be ground in a grinding test of Example 22 of FIG. 11. FIG.

Claims (9)

A kind of vitrified grindstone with coarse structure and homogeneous structure, which is characterized by the combination of abrasive grains and inorganic hollow fillers with inorganic binders. The abrasive particles are filled at a volume ratio of 23 to 35 vol%, and the vitrified grinding stone has homogeneity, which is a standard deviation of 10 or less in the frequency distribution diagram of the area ratio of the abrasive particles, and the abrasive The grain area ratio is the ratio of the solid content including the aforementioned abrasive grains per unit area at a plurality of positions in the cross section of the vitrified grindstone. For example, the vitrified grindstone with the homogeneous structure of the coarse structure of claim 1, wherein the inorganic hollow filler has an average particle diameter of 1.6 times or less relative to the abrasive grains. For example, the vitrified grindstone with the homogeneous structure of the coarse structure of claim 1 or 2, wherein the inorganic hollow filler is filled with a volume ratio of 0.2 to 1.7 times the volume ratio of the abrasive particles. For example, the coarse-grained homogeneous structure vitrified grindstone of any one of claims 1 to 3, wherein the aforementioned inorganic binder is mixed at a volume ratio of 10 to 15 vol%. For example, the vitrified grindstone with a coarse structure and homogeneous structure according to any one of claims 1 to 4 has homogeneity, which has a standard deviation of 6.5 to 8.7 in the frequency distribution diagram of the foregoing abrasive grain area ratio. The vitrified grinding stone with a coarse structure and homogeneous structure according to any one of claims 1 to 5, wherein the aforementioned inorganic hollow filler is filled with a volume ratio of 4 to 45 vol%. The vitrified grinding stone with a coarse structure and homogeneous structure according to any one of claims 1 to 6, wherein the aforementioned inorganic hollow filler has an average particle diameter of 0.6 to 1.6 times the aforementioned abrasive particles. For example, the vitrified grinding stone with a coarse structure and homogeneous structure according to any one of claims 1 to 7, wherein the aforementioned inorganic hollow filler has a volume ratio of 0.2 to 1.67 times the volume ratio of the aforementioned abrasive particles. For example, the vitrified grinding stone with a coarse structure and homogeneous structure according to any one of claims 1 to 8, wherein the aforementioned abrasive particles are alumina-based abrasive materials or silicon carbide abrasive materials, and the aforementioned abrasive particles have a particle size of F80 to F120.