Single-layer vitrified bond grinding wheel

Abstract

To provide a single layer vitrified bond grindstone which prevents abrasive grains from be detached from a bond layer, and can achieve a long-term life.SOLUTION: A single layer vitrified bond grindstone includes a base material 1, a bond layer 3 which is provided on the surface of the base material 1 and is composed of a dense vitreous material, and innumerable abrasive grains 5 which are fixed onto the base material 1 in a single layer by the bond layer 3 in a state of exposed to the surface. The bond layer 3 contains innumerable fillers 7 which have higher melting points than that of the vitreous material, are made of metal powder in a non-oxidation state, and have an average particle diameter of 500 nm or less. In the bond layer 3, more than 0.01 vol.% and less than 10.00 vol.% of the fillers 7 are contained. A density of the abrasive grains 5 on the surface of the bond layer 3 is less than 50%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a single-layer vitrified bond grinding wheel.

Background Art

[0002] Patent Document 1 discloses a conventional single-layer vitrified bond grinding wheel. This single-layer vitrified bond grinding wheel includes a base material, a bond layer, and innumerable abrasive grains. The bond layer is made of a dense glassy material provided on the surface of the base material. The innumerable abrasive grains are fixed in a single layer on the base material by the bond layer with their surfaces exposed. The abrasive grains are super abrasive grains such as diamond or CBN, for example.

[0003] This type of single-layer vitrified bond grinding wheel is embodied as, for example, a dressing tool and is used in dressing processes.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in a single-layer vitrified bond grinding wheel, since the abrasive grains are fixed only in a single layer, if the abrasive grains fall off, the grinding resistance increases and grinding becomes impossible. Particularly when a single-layer vitrified bond grinding wheel is used for dry grinding, the influence of wear of the bond layer due to an increase in grinding resistance and chips becomes large, and the abrasive grains are likely to fall off. For this reason, the single-layer vitrified bond grinding wheel reaches the end of its life early.

[0006] The present invention has been made in view of the above conventional situation, and an object to be solved is to provide a single-layer vitrified bond grinding wheel in which abrasive grains are difficult to fall off from the bond layer and a long-term life can be realized.

Means for Solving the Problem

[0007] The single-layer vitrified bond grinding wheel of the present invention includes a base material, a bond layer containing a dense glassy substance provided on the surface of the base material, and innumerable abrasive grains fixed in a single layer on the base material by the bond layer with their surfaces exposed. The bond layer contains innumerable fillers made of a metal substance with a melting point higher than that of the glassy substance, in a non-oxidized state, and having an average particle size of 500 nm or less. The filler is contained in the bond layer in an amount exceeding 0.01% by volume and less than 10.00% by volume. The density of the abrasive grains on the surface of the bond layer is less than 50%, which is a characteristic feature.

[0008] The inventors have intensively studied to improve the retention of abrasive grains in a single-layer vitrified bond grinding wheel. As a result, in a single-layer vitrified bond grinding wheel where abrasive grains have fallen off, cracks have occurred in the bond layer around the abrasive grains, and it has been found that the abrasive grains have fallen off during grinding due to these cracks. Also, cracks in the bond layer around the abrasive grains are caused by the fact that the wettability of the abrasive grains with respect to the molten glass is too good, so that the molten glass clings around the abrasive grains, and as a result, cracks have occurred after the glass has solidified. Then, in order to suppress the cracks in the bond layer around the abrasive grains, the idea of adding minute metal particles as fillers to the bond layer was conceived, and after many trials and errors, the appropriate range of the particle size of this filler and the like were found, and the present invention was completed.

[0009] According to the test results of the inventors, if innumerable fillers made of a metal substance with a melting point higher than that of the glassy substance, in a non-oxidized state, and having an average particle size of 500 nm or less are contained in an appropriate amount in the bond layer, and moreover, if the abrasive grains are fixed in an appropriate amount on the surface of the bond layer, the abrasive grains are firmly held in the bond layer and it becomes difficult for the abrasive grains to fall off from the bond layer, so that a long-term life can be realized.

[0010] The inventors speculate the reason as follows. That is, if such a filler is contained in an appropriate amount in the bond layer, since the filler is a tough metal, it is considered that the bond layer is elastically reinforced by the filler and cracks are less likely to occur in the bond layer. Further, the filler makes the wettability of the abrasive grains with respect to the molten glass appropriate, and thus it is considered that the molten glass is prevented from clinging around the abrasive grains, and the occurrence of cracks in the bond layer around the abrasive grains after the glass solidifies is also suppressed.

[0011] Therefore, in the single-layer vitrified bond grinding wheel of the present invention, the abrasive grains are difficult to fall off from the bond layer, and a long service life can be realized.

[0012] As the base material, in addition to the base material having rigidity, a base material having flexibility to such an extent that it does not deform the bond layer can be adopted. As the base material having rigidity, ceramics such as alumina, silicon nitride, silicon carbide, zirconia, mullite, metals such as carbon steel, cemented carbide, cast iron, pure iron, chromium steel, iron, SUS, copper, glass having a strain point of 600 °C or higher, etc. can be adopted. Among them, metals are preferable, and in particular, metals such as carbon steel, with a linear expansion coefficient (×10 -6 / °C) of about 10 to 15 are preferable. As the base material having flexibility, a sheet made of a woven fabric or a non-woven fabric composed of fibers such as natural fibers, synthetic fibers, and carbon fibers, synthetic resins such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyimide (PI), polyethylene naphthalate (PEN), aramid, single-layer or multi-layer films made of metals such as aluminum and copper can be adopted.

[0013] As the bond layer made of a dense glassy material, those with high adhesion to the base material, that is, those with a linear expansion coefficient close to that of the base material are preferred. That is, a powder or paste of a glass binder containing a frit of glass having a linear expansion coefficient close to that of the base material can be adopted, and a material formed by melting and solidifying the powder or paste on the base material can be adopted. The present invention is a single-layer vitrified bond grinding wheel, and since the bond layer only fixes the abrasive grains in a single layer, the bond layer substantially does not contain pores.

[0014] As the abrasive grains, silica, alumina, zirconia, silicon carbide, silicon nitride, mullite, BN such as CBN, yttria-stabilized zirconia, diamond, etc. can be adopted. Among them, in addition to diamond as super abrasive grains, BN such as CBN is preferred.

[0015] The filler contained in the bond layer has a melting point higher than that of the glassy material, is made of a non-oxidized metallic material, and has an average particle size of 500 nm or less. Specifically, Ni, Cu, Fe, Ag, etc. can be adopted as such a filler. Among these, Ni is particularly preferred. The bond layer can contain one or more of Ni, Cu, Fe, Ag, etc. Also, an alloy of these metals may be used.

[0016] In the single-layer vitrified bond grinding wheel of the present invention, the filler is contained in the bond layer in an amount exceeding 0.01% by volume and less than 10.00% by volume. According to the test results of the inventors, it is preferable that the filler is contained in the bond layer in an amount of 0.10 to 5.00% by volume. If the content of the filler in the bond layer is too small, the effect of adding the filler is not sufficient. If the content of the filler in the bond is too large, the bond layer cannot hold the abrasive grains sufficiently. It is more preferable that the filler is contained in the bond layer in an amount of 1.00 to 5.00% by volume. It is even more preferable that the filler is contained in the bond layer in an amount of 1.00 to 3.00% by volume.

[0017] In the single-layer vitrified bond grinding wheel of the present invention, the density of abrasive grains on the surface of the bond layer is less than 50%. According to the test results of the inventors, the density of abrasive grains on the surface of the bond layer is preferably 40% or less. If the abrasive grain density is too high, the chips are likely to be clogged and the effect of the filler cannot be obtained. The density of abrasive grains on the surface of the bond layer is more preferably 30%. The density of abrasive grains on the surface of the bond layer is even more preferably 5% or less.

Advantages of the Invention

[0018] In the single-layer vitrified bond grinding wheel of the present invention, since the abrasive grains are difficult to fall off from the bond layer, a long service life can be realized.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the present invention will be described with reference to Tests 1 to 4, and examples and comparative examples will be described.

[0021] (Test 1) First, a base material made of S45C as a carbon steel for machine structures, a glass binder whose composition is shown in Table 1, and abrasive grains composed of diamond (average particle size 91 μm) under 170 mesh were prepared. The average particle size was determined according to JIS B4130. Also, as a filler, Ni powder whose average particle size is shown in Table 2 was prepared. The particle size of the filler was measured by the dynamic light scattering method, and D(50) in volume conversion was taken as the average particle size (Zetasizer Nano manufactured by Malvern). Further, the particle size distribution data of the filler with an average particle size of 180 nm for Test Specimens 1-3 are shown in Fig. 4.

[0022] [Table 1]

[0023] Using terpineol as a solvent, the glass binder is made into a paste. Each filler is mixed into this paste to obtain a paste containing the filler. The content of the filler in the paste is 1.00% by volume based on the solid content of the paste. That is, if the bond layer is formed only by the paste containing the filler, the filler volume percentage in the bond layer will be 1.00% by volume.

[0024] The paste containing the filler is coated on the base material to obtain a first preparation. Subsequently, abrasive grains are sprinkled on each first preparation to obtain a second preparation. Each second preparation is dried to evaporate the solvent of the coating layer to obtain a third preparation. Each third preparation is fired at 800 °C in a non-oxidizing atmosphere to melt the glass binder, and after a certain period of time, it is gradually cooled. In this way, the glass binder is solidified to form a bond layer composed of a dense glassy material. It is cooled to room temperature to obtain each of Test Specimens 1-1 to 6.

[0025] The average particle size of the filler is 60 nm for Test Specimen 1-1, 100 nm for Test Specimen 1-2, 180 nm for Test Specimen 1-3, 300 nm for Test Specimen 1-4, 500 nm for Test Specimen 1-5, and 1000 nm for Test Specimen 1-6.

[0026] In each of the test specimens 1-1 to 6, the protrusion amount of the abrasive grains, that is, the average value of the length by which each abrasive grain protrudes from the bond layer, is 35 μm. The thickness of the bond layer is 50 μm ± 5 μm for all of them.

[0027] Under the following conditions, each of the test specimens 1-1 to 6 was used for grinding, and the life due to the falling off of the abrasive grains was evaluated. Workpiece: Single-crystalline Si wafer Grinding conditions: 10 m / min Depth of cut: 10 μm Grinding method: Dry grinding

[0028] At this time, taking one pass, cutting is performed from one side of the strip of the 10-mm-wide workpiece, and the workpiece and each test specimen are translated in parallel to the other side. When there was falling off of the abrasive grains within 10 passes, it was marked as "×", when there was falling off of the abrasive grains beyond 10 passes and within 50 passes, it was marked as "△", when there was falling off of the abrasive grains beyond 50 passes and within 100 passes, it was marked as "〇", and when there was no falling off of the abrasive grains even after 100 passes, it was marked as "◎". The results are shown in Table 2.

[0029]

Table 2

[0030] As shown in Table 2, for test specimens 1-6, the average particle size of the filler in the bond layer is 1000 nm, and falling off of the abrasive grains occurred within 10 passes. On the other hand, for test specimens 1-1 to 5, since the average particle size of the filler in the bond layer is 500 nm or less, it has become difficult for the abrasive grains to fall off from the bond layer. In particular, for test specimens 1-2 to 4, since the average particle size of the filler is 100 to 300 nm, falling off of the abrasive grains does not occur even beyond 100 passes. Therefore, it can be seen that test specimens 1-1 to 5 can achieve long-term life.

[0031] (Test 2) As shown in Table 3, the filler content in the bond layer is varied, and Test Specimens 2-1 to 2-7 are obtained in the same manner as in Test 1. The volume percentage of the filler in the bond layer is 0.00 volume% for Test Specimen 2-1, 0.01 volume% for Test Specimen 2-2, 0.10 volume% for Test Specimen 2-3, 1.00 volume% for Test Specimen 2-4, 3.00 volume% for Test Specimen 2-5, 5.00 volume% for Test Specimen 2-6, and 10.00 volume% for Test Specimen 2-7.

[0032] A schematic cross-sectional view of Test Specimen 2-4 is shown in FIG. 1. A schematic cross-sectional view of Test Specimen 2-1 is shown in FIG. 5. As shown in FIGS. 1 and 5, Test Specimens 2-1 and 2-4 include a base material 1, a bond layer 3 made of a dense glassy material provided on the surface of the base material 1, and innumerable abrasive grains 5 fixed in a single layer on the base material 1 by the bond layer 3 with their surfaces exposed. As shown in FIG. 1, Test Specimen 2-4 contains innumerable fillers 7 in the bond layer 3. On the other hand, as shown in FIG. 5, Test Specimen 2-1 does not contain any fillers in the bond layer 3.

[0033] Under the same conditions as in Test 1, each of Test Specimens 2-1 to 2-7 was used for grinding, and the life due to the falling off of the abrasive grains was evaluated. The results are shown in Table 3.

[0034]

Table 3

[0035] As shown in Table 3, if an appropriate amount of filler 7 is present in the bond layer 3, as in Test Specimens 2-3 to 6, the abrasive grains 5 are less likely to fall off from the bond layer 3 and the life is prolonged. In particular, if the volume percentage of the filler in the bond layer 3 is 1.00 to 5.00 volume%, as in Test Specimens 2-4 to 6, the life is even longer. Further, if the volume percentage of the filler in the bond layer 3 is 1.00 to 3.00 volume%, as in Test Specimens 2-4 to 5, the life is even longer.

[0036] On the one hand, when the volume percentage of the filler 7 in the bond layer 3 is 0.01% by volume or less as in the test specimens 2-1 to 2-2, or when the volume percentage of the filler 7 in the bond layer 3 is 10.00% by volume or more as in the test specimen 2-7, the holding force of the abrasive grains 5 decreases.

[0037] (Test 3) As shown in Table 4, the density of the abrasive grains 5 on the surface of the bond layer 3 is varied in various ways, and test specimens 3-1 to 3-6 are obtained in the same manner as in Test 1. The abrasive grain density is 60% for test specimen 3-1, 50% for test specimen 3-2, 40% for test specimen 3-3, 30% for test specimen 3-4, 5% for test specimen 3-5, and 1% for test specimen 3-6. The density of the abrasive grains 5 on the surface of the bond layer 3 (%) refers to the ratio of the area occupied by the abrasive grains on the tool surface. The density is first obtained by acquiring a 100-fold SEM image (JEOL JSM-6610, secondary electron image of the surface), binarizing this SEM image with imageJ (image processing software) to separate the bond layer part and the abrasive grain part, and calculating the area ratio occupied by the abrasive grains.

[0038] Under the same conditions as in Test 1, each of the test specimens 3-1 to 3-6 was used for grinding, and the life due to the fall-off of the abrasive grains was evaluated. The results are shown in Table 4.

[0039]

Table 4

[0040] As shown in Table 4, it is preferable that the abrasive grains 5 are fixed at 40% or less on the surface of the bond layer 3. It is more preferable that the abrasive grains 5 are fixed at 30% or less on the surface of the bond layer 3. It is even more preferable that the abrasive grains 5 are fixed at 1% or more and 5% or less on the surface of the bond layer 3. When the abrasive grain density on the surface becomes 50% or more, the chips are likely to be clogged, and the effect of adding the filler cannot be obtained.

[0041] (Test 4) Vary the types of filler 7 and obtain test specimens 4-1 to 4-6 in the same manner as in Test 1. For filler 7, test specimen 4-1 is alumina, test specimen 4-2 is 3YSZ (3 mol% yttria-stabilized zirconia), test specimen 4-3 is Fe, test specimen 4-4 is Ni, test specimen 4-5 is Cu, and test specimen 4-6 is Ag.

[0042] Under the same conditions as in Test 1, each of the test specimens 4-1 to 4-6 was used for grinding, and the life due to the abrasion of the abrasive grains was evaluated. The results are shown in Table 5.

[0043]

Table 5

[0044] As shown in Table 5, it can be seen that as filler 7, Fe, Ni, Cu, Ag, etc. can be adopted. In particular, it can be seen that Ni is preferable as filler 7.

[0045] In the above, the present invention has been described with reference to test specimens 1-1, etc. However, the present invention is not limited to the above test specimens 1-1, etc., and it goes without saying that it can be appropriately modified and applied without departing from the gist thereof.

Industrial Applicability

[0046] The present invention can be used for dressing tools and the like.

Explanation of Reference Numerals

[0047] 1... Base material 3... Bond layer 5... Abrasive grains 7... Filler

Claims

1. A base material, a bond layer containing a dense glassy material provided on the surface of the base material, and innumerable abrasive grains fixed in a single layer on the base material by the bond layer with their surfaces exposed, the bond layer contains innumerable fillers made of a metallic material in a non-oxidized state with a melting point higher than that of the glassy material and an average particle size of 500 nm or less, the fillers are contained in the bond layer in an amount exceeding 0.01% by volume and less than 10.00% by volume, a single-layer vitrified bond grinding wheel, characterized in that the density of the abrasive grains on the surface of the bond layer is less than 50%.

2. The single-layer vitrified bond grinding wheel according to claim 1, wherein the fillers are contained in the bond layer in an amount of 0.10 to 5.00% by volume.

3. The single-layer vitrified bond grinding wheel according to claim 1 or 2, wherein the density of the abrasive grains on the surface of the bond layer is 40% or less.

4. The single-layer vitrified bond grinding wheel according to any one of claims 1 to 3, wherein the fillers are composed of at least one of Ni, Cu, Fe, and Ag.

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