KR200317141Y1 - Composite fine ceramic stone for grinding of difficult-to-cut materials - Google Patents

Abstract

The present invention relates to a ceramic whetstone which is a composite fiber for grinding difficult materials such as ceramics such as Al ₂ O ₃ , SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, crystals, and Si materials, When using diamond grindstone, metal diamond grindstone and non-refined diamond grindstone, problems such as breakage of the workpiece, dimples, cracks, scratches, deterioration of the workpiece strength, etc. are eliminated. In addition to diamond particles, diamond particles finer than # 2,000 can be used to make the working surface beautiful and to increase the grinding ratio and life of the grindstone.

The present invention for achieving the above object, one or two or more kinds of inorganic materials such as GC, A, WA, TiC, graphite, etc. in the range of 10% (VoL) to 50% (VoL) is added as auxiliary particles, diamond particles The concentration of 20% (Vol) to 60% (Vol), the porosity of the fine ceramic binder grindstone to 5% (Vol) to 40% (Vol) or less, and the chemical composition of the fine ceramic binder SiO ₂ 45 to 55 % (Wt), Al ₂ O ₃ 15-32% (wt), SiC 18-27% (wt), B ₂ O ₃ 7-17% (wt), RO 4-16% (wt), R ₂ O 2 to 18% (wt) and copper (Cu), Co (cobalt), nickel (Ni), tungsten (W), so that the volume ratio of the metal powder after sintering is 10% (Vol) to 50% (Vol) A single metal powder such as iron (Fe) or two or more alloy powders (CuSn, CuZn, etc.) are added, and a thermosetting resin is mixed and molded within a range of 10 to 60% (vol), and then sintered by mixing with a binder. Its purpose is to provide fine ceramic whetstones.

When grinding fine materials such as ceramics such as Al ₂ O ₃ , SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, quartz crystals, and Si materials, using the fine ceramic grindstone shown in FIG. 1 of the present invention In addition, the use of conventional resin diamond grindstones and metal diamond grindstones and non-refined diamond grindstones, which have been problematic in the past, prevents the generation of cracks, scratches, and strength deterioration, and prevents diamond particles larger than # 2,000. , Fine diamond particles of # 2,000 or less can be used to make the working surface beautiful, and the grinding ratio and life of the grindstone are significantly increased.

[ Index word ]

Al ₂ O ₃ , SiC, Ceramic, TiC, Cermet, Quartz, Gem, Crystal, Si, Difficult Materials, Grinding, Cutting, Fine Ceramics, Binder, Diamond Particle, Auxiliary Particle, SiC, Pore, Metal Powder, Dimple, Scratch

Description

Composite fine ceramic stone for grinding of difficult-to-cut materials}

Ceramics such as Al ₂ O ₃ and SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, crystals and Si materials are very hard and very brittle, so when grinding and cutting using a grindstone This produces a decrease in strength, and chipping is likely to occur in the workpiece. In the case of grinding and cutting such a difficult material using a low-grinding resin diamond grindstone, since a large internal stress is generated in the workpiece due to the grinding resistance and the heat of grinding, it is easy to cause cracking. When grinding such hard grinding materials with ordinary grindstone grindstones using low-hardness particles, grinding performance is very poor, grinding resistance is very high, and the tendency of grinding and breaking of particles of grindstone is remarkable. Due to the thermal damage of the workpiece, cracks are generated in the workpiece, and macroscopic fracture is likely to occur. Conventionally, when grinding such a difficult material, a resin bond diamond grindstone manufactured by mixing plastic-based resin paper and abrasive grains such as diamond powder and pressing and heating at around 160 ° C. is used. Due to its nature, it is a kind of plastic, and due to the limitation of strength and toughness, the abrasive grains are dropped and damaged at the time of grinding by about 40% or more, and the grinding property is inferior. There was discomfort that requires truing and dressing processes.

In addition, the metal bond diamond grindstone is a diamond grindstone prepared by mixing metal powder and abrasive grains and then sintering at about 600 ° C. to 800 ° C., which has high toughness and hardness after sintering of the metal alloy, and thus protrudes the diamond particles during grinding. Grinding is difficult because it makes it difficult, and therefore dressing must be frequently performed during grinding, and thus, it has been difficult to use for grinding of such a difficult material.

On the other hand, when grinding such a difficult material with a diamond grinding wheel using a conventional vitrified binder, roughing was mainly used, it was difficult to finish grinding, it was very difficult to manufacture a diamond grindstone in a complicated shape during the molding process. In the case of sintering by using the vitrified powder alone as the binder, since the vitrified binder is in the form of particles before sintering, it is difficult to transmit the same pressure as a whole, so that the density of the molded body varies from site to site. Therefore, in many cases, a molded product can only be manufactured by simply applying pressure vertically. In this case, the density in the vertical direction and the horizontal direction is different, and also the density change between the inside and the outside is remarkable, so that defects such as cracks occur during sintering. It cannot be used as a whetstone. Therefore, only a simple shape can be formed by applying only a vertical pressure or a horizontal pressure at the time of molding, and only a simple stone can be produced.

The present invention is found in the workpieces when the conventional diamond grindstone is used for grinding difficult materials such as Al ₂ O ₃ , ceramics such as SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, quartz crystals and Si materials, It aims at suppressing generation | occurrence | production of a crack, strength fall, and a scratch. In addition, diamond particles larger than # 2,000, as well as finer diamond particles than # 2,000 can be used, and the workpiece has high precision and beautiful processing surface, difficult to maintain the sharpness of the diamond particles, falling off, unstable cutting performance, Designed to solve problems such as short grinding wheel life, low grinding ratio, shape deformation during use, and eye filling, the concentration of diamond particles, the type and content of auxiliary particles and metal powder, chemical composition of fine ceramic binder, Molding and sintering are performed by adjusting the sintering conditions appropriately so that the hardness is very high and brittle, such as ceramics such as Al ₂ O ₃ , SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, quartz, and Si materials. Its purpose is to provide a ceramic whetstone that is a composite that is suitable for grinding difficult-to-reach materials.

1 is a state diagram showing the structure of the ceramic grinding wheel

<Description of the code | symbol about the principal part of drawing>

1: Diamond Particle 2: Auxiliary Particle

3: fine ceramic binder 4: metal powder

5: resin 6: pore

The ceramic whetstone, which is the composite of the present invention, has a concentration of diamond particles of 20% (Vol) to 60% (Vol), and inorganic materials such as GC, A, WA, TiC, graphite, and the like as 10 to 50% range as auxiliary particles. Chemical composition of fine ceramic binder, SiO ₂ 45-55% (wt), Al ₂ O ₃ 15-32% (wt), SiC 18-27% (wt), B ₂ O ₃ 7 to ₁₇ % (wt), RO 4 to 16% (wt), R ₂ O 2 to 18% (wt), copper (Cu), cobalt (Co), nickel (Ni), tin (Sn) , Single metal powders such as zinc (Zn), tungsten (W), iron (Fe), and powder particles of two or more kinds of metal compounds (CuSn, CuZn, etc.) are added, and at least one type of thermosetting resin is 10 to 60%. By mixing and molding and sintering within the (vol) range, the porosity of the fine ceramic grindstone is maintained in the range of 5% (Vol) to 40% (Vol).

The grinding wheel of the present invention absorbs and releases the grinding heat during grinding by homogenizing the particles which lead the grinding and the pores which bring about the discharge and cooling effect of the chip when grinding, and the binder that binds the abrasive plays an important role. have. The effective combination of these characteristics can significantly increase the grinding and grinding wheel life and reduce the manufacturing cost of the grinding wheel. The concentration of diamond particles, which lead the grinding of composite fine ceramic diamond grindstones, is preferably 20% to 60% (Vol). When the concentration is 19% or less, ceramics such as Al ₂ O ₃ , SiC, TiC, TiN, TiCN, etc. When grinding a variety of difficult materials such as cermet, quartz, gemstone, quartz, and Si materials, the grinding performance is good, but the shape of the grindstone is severe, the life of the grindstone is shortened. This occurs, resulting in thermal deformation of the workpiece, almost no shape deformation, and a relatively long service life. Therefore, the concentration is optimally between 20% and 60% (Vol).

In addition, among the components of the whetstone of the present invention, the change of pores is a very important factor. The abrasive grains change as described above depending on their contents, but the pores change the porosity of fine ceramic diamond grindstone when grinding hard materials 5% to 40%. If the porosity is 4% or less, the grinding property is poor, the shape deformation is small, and the service life is long. On the contrary, when the porosity is 41% or more, the grinding property is good but the shape deformation is severe. Since the service life becomes inferior, the porosity is appropriately in the range of 5% to 40% (Vol).

In addition, in the manufacture of the whetstone of the present invention, since diamond is oxidized at about 700 ° C., a binder having a composition that is likely to change into a glassy substance at a low temperature should be selected, and the chemical composition is 45 to 55% of SiO ₂ . (wt), Al ₂ O ₃ 15-32% (wt), SiC 18-27% (wt), B ₂ O ₃ 7-17% (wt), RO 4-16% (wt), R ₂ O 2 The range of -18% (wt) is shown by the optimal composition. In the above chemical composition, RO is an alkaline earth metal oxide, at least one oxide selected from ZnO, PbO, CaO, MgO, BaO, FeO, and R ₂ O is an alkali metal oxide, which is Li ₂ O, Na ₂ O, K. _At least one oxide selected from ₂ O is represented.

The content of B ₂ O ₃ is set to 7 to 17% because if the content of B ₂ O ₃ is too low, a high sintering temperature is required for sufficient sintering, and thus it is difficult to achieve the object of the present invention. If the content of B ₂ O ₃ is too high, the melt viscosity is low and the fluidity is increased is because the bonding strength is lowered.

In the fine ceramic binder of the present invention, the content of SiO ₂ is 45 to 55%. If the content of SiO ₂ is too low, the bond strength is lowered. If the content of SiO ₂ is too high, a high sintering temperature is required for sufficient sintering, and it is difficult to achieve the object of the present invention.

The content of Al ₂ O ₃ according to the present invention is 15-32%. If the content of Al ₂ O ₃ is too low, the stability of the binder after sintering is lowered. In addition, when the content of Al ₂ O ₃ is too high, the melt viscosity becomes high and the wettability with the particles is lowered.

If the content of CaO and MgO is too low, a high sintering temperature is necessary for sufficient sintering. If the content of CaO and MgO is too high, the melt viscosity is low, the fluidity is increased, the particle retention force is low, and the brittleness is high, and the impact resistance is low. . In view of the stability of the binder after sintering, CaO and MgO are preferably set to 2.0 to 2.6% of CaO and 3.7 to 4.3% of MgO.

In the present invention, an appropriate amount of MgO and ZnO should be added as an oxide to prevent oxidation of the mixed particles, to reduce the coefficient of thermal expansion, to lower the surface tension of the binder in the molten state, to increase the wettability of the particles, and to obtain strong particle support. . MgO and ZnO lower the coefficient of thermal expansion of the binder when both components coexist, reduce shrinkage due to sintering, and form a uniform and strong bonding structure. A proper amount of ZnO is added to the binder to lower the viscosity of the melted binder to lower the coefficient of thermal expansion and to increase the bearing capacity of the particles when cooling is completed after sintering, but when the MgO is less than 3.3%, the binder does not have a remarkable effect of 5.2%. In the case of a large amount exceeding, the amorphous viscosity at the time of melting is too low, and the particle holding power is weak, and in the case of a small amount of ZnO less than 2.8%, there is little effect of having a stable and dense grinding wheel structure with the decrease of the coefficient of thermal expansion. On the contrary, in a large amount exceeding 9.2%, fire resistance becomes remarkable and the fusion effect to the particle surface is prevented, and it is unpreferable. In addition, the solubility, workability, and uniformity of the glass can be improved by containing 3% or less of PbO. However, when the content exceeds 3%, the amount of matrix grass after crystallization is increased to increase the dielectric loss, which is not preferable.

In addition, if the content of K ₂ O, Na ₂ O, Li ₂ O is too low, a high sintering temperature is required for sufficient sintering. If the content is too high, the thermal expansion coefficient becomes high, causing stress concentration at the boundary with the particles. It is easy to fall off, and furthermore, the difference in thermal expansion coefficient with a particle becomes large, and the bonding force falls. Thus, _{K 2 O 2.9~3.5%, Na 2} O 7.6~8.2%, it is preferable that the content of Li ₂ O 1.8~2.4%.

B ₂ O ₃ , Li ₂ O, F ₂ , P ₂ O ₅ , Na ₂ O, K ₂ O act as various solvents that melt at a relatively low temperature of 700 ° C to facilitate the amorphousization of SiO _{2 in} the binder component. In order to prevent oxidation of diamond and TiC, which are fine particles, it is not preferable to contain a large amount of B ₂ O ₃ , Li ₂ O, F ₂ , P ₂ O ₅ , Na ₂ O, and K ₂ O, which are strong melt agents in the binder.

The grinding wheel of the present invention is composed of copper (Cu), cobalt (Co), nickel (Ni), tin (Sn), zinc (Zn), tungsten (volume ratio after sintering of about 10% (Vol) to 50% (Vol)). W), dispersing at least one or more single metal powders or alloy powder particles in iron (Fe) in a fine ceramic binder phase, the average particle diameter of which depends on the mesh of the diamond and CBN particles and is smaller than the size of the diamond particles. It is preferable to use powder powder, and sintering is performed under conditions that do not oxidize such metal powder in the pressure sintering process, and metal powder satisfying these conditions should be selected and added according to its use characteristics, for example, grinding of workpieces. In case of dry condition, Cu powder with good thermal conductivity is added to the binder.W and Co powder is used to minimize abrasion resistance and deformation, and Ni powder and brittleness are required when toughness is required. If required, Fe powder is used, and the binder should be selected according to the characteristics of fine ceramic diamond and CBN grindstone for hard cutting materials.

Such metal powder is present in a fused state between the fine ceramic binders. Metal powder suppresses the occurrence of problems such as cracking due to difference in thermal expansion coefficient between fine ceramic binder and diamond during sintering, prevents premature dropping of diamond particles during grinding, and lowers the grinding resistance according to the characteristics thereof. .

The grindstone of the present invention adds at least one or more thermosetting resins selected from phenol resins and epoxy resins within a range of 10 to 60% (vol), and the addition of such resins prevents the grinding of diamond grindstones during grinding, It increases the grinding ratio and has the effect of maintaining the sharpness of the diamond particles.

In addition, the diamond particles bonded by the fine ceramic binder have a high grinding ratio because the retaining force of the diamond particles is increased and the premature dropping of the diamond particles is suppressed. Therefore, the diamond whetstone using the ceramic binder, which is the composite of the present invention, can be manufactured in various shapes that cannot be obtained from the bituminous grindstone, and has the advantage of obtaining physical and mechanical properties. The grinding wheel of the present invention enables not only diamond particles larger than # 2,000, but also diamond particles finer than # 2,000.

<Example>

As shown in Examples (1) and (2) shown in Table 1 below, the chemical constituents of the composite binders of all the examples were SiO ₂ 50% (wt), Al ₂ O ₃ 20% (wt), and SiC 25 % (Wt), B ₂ O ₃ 11% (wt), RO 9% (wt), R ₂ O 10% (wt) was constant, the resin was used in Example (1), the phenol resin, In Example (2), epoxy resin was used, and in Comparative Example (1) and Comparative Example (2) of Table 1, resin bond diamond grindstone was used, and Comparative Example (3) and Comparative Example (4) were non-refined diamonds. Whetstone was used, and Comparative Example (5) and Comparative Example (6) used a metal bond diamond grindstone.

TABLE 1

Table 2 shows the grinding conditions at the time of experiment, and Al ₂ O ₃ ceramics were prepared using the grindstones of Example (1), Example (2) and Comparative Example (1) to Comparative Example (6) shown in Table 1. Grinding. The dimensions of the specimens were 50 mm long, 5 mm long, and 5 mm high, and 20 specimens for each condition were plunge ground for 3 minutes in the transverse direction. The cutting resistance during grinding was measured by the vertical force, the grinding ratio was calculated by measuring the grinding force of the grindstone after grinding, and the average value of the bending strength was obtained by performing a four-point bending test with the grinding surface on the tension side. The grinding ratio represents the ratio of the abrasive wear to the removal amount of the workpiece during grinding, and the higher the grinding ratio, the longer the grindstone life and the less abrasive wear. In addition, the crack depth of the grinding surface was measured using a scanning electron microscope, and the surface roughness value of the grinding surface was determined using a tactile surface roughness measuring instrument, and all measured values were expressed as average values for 20 specimens.

TABLE 2

Table 3 shows the results of measuring the grinding ratio, the bending strength, the surface roughness, the crack depth, and the grinding resistance during grinding in the case of grinding under the grinding conditions of Table 2. The grinding resistance is shown here only for normal forces. As shown in Table 3, in Examples (1) and (2) of the present invention, the grinding ratio is three times or more, and the grindstone life is three times or more, compared with Comparative Examples (1) to (6). The values of bending strength are also significantly larger in Examples (1) and (2) than in Comparative Examples (1) to (6), as shown in Table 3 due to the significantly smaller crack depth during grinding. As described above, the grinding of the grinding wheel of the embodiment of the present invention significantly reduces the damage to the workpiece compared with the grinding of the conventional grinding wheel. In addition, in Examples (1) and (2), the surface roughness value is significantly smaller than that of Comparative Examples (1) to (6), which is a grinding surface when grinding with a grinding wheel of the present invention compared with grinding with a conventional grinding wheel. This means it's beautiful. From the experimental results, the composite of the present invention is used for grinding of hard and highly brittle, hard-to-hard materials such as ceramics such as Al ₂ O ₃ , SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, quartz, and Si materials. A fine ceramic whetstone can be said to perform very well.

TABLE 3

As described above, the ceramic diamond whetstone, which is a composite of the present invention, is a workpiece during grinding of hard materials such as ceramics such as Al ₂ O ₃ , SiC, cermets such as TiC, TiN, TiCN, quartz, gemstones, quartz crystals, and Si materials. The occurrence of cracks and deterioration in strength are suppressed, the work piece is more precise and the surface is beautiful, the sharpness of the diamond particles is always maintained, and the grindstone life is long. Ceramic diamond grindstone, which is the compound of the present invention, is hard to generate welding or blindness during grinding of difficult materials, and has high retaining power of diamond particles, so there is little fracture or dropping of abrasive grains, so the tool life is very high and the grinding surface is also very good. In addition to diamond particles larger than # 2,000, finer diamond particles than # 2,000 can be used.

Claims (6)

The concentration of diamond particles or CBN particles is 20% to 60% (Vol), and as auxiliary particles, inorganic substances such as GC, A, WA, TiC, graphite, etc. are added in a single or at least one type, in a range of 10 to 50%, The porosity, which is a component of fine ceramic grindstone, is composed of 5% to 40% (Vol), and not only diamond particles larger than # 2,000 but also fine diamond particles of # 2,000 or less can be used, and Al ₂ O ₃ , SiC Ceramic grinding wheel for composite grinding for hard materials such as ceramics, cermets such as TiC, TiN, TiCN, quartz, gemstones, quartz and Si materials. The chemical composition of the fine ceramic binder according to claim 1, wherein the chemical composition of the fine ceramic binder is SiO ₂ 45-55% (wt), Al ₂ O ₃ 15-25% (wt), SiC 18-27% (wt), B ₂ O ₃ 7- 17% (wt), RO 4-16% (wt), R ₂ O 2-18% (wt), and a fine ceramic binder pulverized to be smaller than the diamond particles is added, and larger than # 2,000 In addition to diamond particles, fine diamond particles of # 2,000 or less can be used, and for grinding abrasive materials such as ceramics such as Al ₂ O ₃ and SiC, cermets such as TiC, TiN and TiCN, quartz, gemstones, quartz crystals and Si materials. Composite Fine Ceramic Whetstone. The ceramic whetstone according to claim 1, wherein at least one or more thermosetting resins selected from phenol resins and epoxy resins are added and molded and sintered within a range of 10 to 60% (vol). The method of claim 1, wherein a single particle of a metal powder such as copper (Cu), Co (cobalt), nickel (Ni), tungsten (W), iron (Fe) or the like smaller than the diamond particle size in the production of fine ceramic grindstone or A ceramic grinding wheel comprising at least two alloy powders (CuSn, CuZn, etc.) mixed with a binder and sintered, wherein the volume fraction after sintering the metal powder particles is 10% (Vol) to 50% (Vol). The ceramic grinding wheel according to claim 2, wherein at least one or more thermosetting resins selected from phenol resins and epoxy resins are added and molded and sintered within a range of 10 to 60% (vol). The method of claim 2, wherein the average particle diameter of the metal powder in the manufacture of fine ceramic grinding wheels depends on the size of the diamond and CBN particles, copper (Co), Co (cobalt), nickel (Ni) smaller than the size of the diamond and CBN particles ), Single particles of metal powders such as tungsten (W), iron (Fe) or two or more alloy powders (CuSn, CuZn, etc.) are mixed with a binder and sintered, and the volume ratio after sintering the metal powder particles is 10% (Vol) It is -50% (Vol), The composite fine ceramic grindstone characterized by the above-mentioned.