JPH1015832A - Binder for vitrified grinding wheel, manufacture of vitrified grinding wheel using the binder, and vitrified grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for a reducing atmosphere and an inert atmo sphere even when diamond ultra-fine abrasives are sintered without being oxi dized by including specific parts by weight of SiO2 , Al2 O3 , B2 O3 , etc. SOLUTION: This binder for a vitrified grinding wheel is composed of 47 to 53 parts by weight of SiO2 , 17 to 23 parts by weight of Al2 O3 , 9 to 15 parts by weight of B2 O3 , 6 to 14 parts by weight of (CaO+MgO), and 4 to 16 parts by weight of (K2 O+Na2 O+Li2 O). The SiO2 , Al2 O3 , B2 O3 , CaO, MgO, K2 O, Na2 O, and Li2 O can be used in the form of raw materials similar to raw materials used in the manufacture of glass, etc. These components are mixed in a desired ratio, baked at high temperatures for vitrification, and crushed to obtain the binder. The binder for the vitrified grinding wheel enables manufacture of a good vitrified grinding wheel even if the temperature at which the binder mixed with abrasives is sintered is not more than 720 deg.C. The sintering temperature is preferably 680 deg.C or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vitrified grinding wheel technology, and more particularly to a binder for a vitrified grinding wheel, a method for manufacturing a vitrified grinding wheel using the same, and a vitrified grinding wheel.

[0002]

2. Description of the Related Art
There has been proposed a vitrified superabrasive grindstone in which superabrasives such as diamond and cubic boron nitride (CBN) are hardened by vitrified bonds (see JP-A-1-38628). Vitrified superabrasive stones containing diamond superabrasives are suitable for grinding ceramic materials, and CBN
A vitrified superabrasive grindstone containing superabrasive grains is suitable for grinding steel-based materials. In such a superabrasive grindstone, in addition to superabrasive grains such as diamond and CBN, if necessary, silicon carbide (SiC) abrasive grains and alumina (Al) General abrasive grains such as ₂ O ₃ ) abrasive grains can also be used in combination.

[0003] When diamond super-abrasive grains are used, the following precautions are required in the production of a grinding stone. That is, diamond rapidly oxidizes at a temperature exceeding about 720 ° C., and its excellent properties as abrasive grains are impaired. Therefore, a binder is added and sintering is performed at a high temperature exceeding 720 ° C. to form a grindstone. In the case of production, sintering must be performed in a reducing atmosphere to prevent oxidation. However, since most components of the binder for vitrified grinding wheels are composed of oxides, when sintering is performed in a reducing atmosphere, a reduction phenomenon occurs in the binding agent, and the strength of the manufactured grinding wheel is reduced. Therefore, sintering may be performed in an inert atmosphere such as a nitrogen atmosphere instead of the reducing atmosphere. JP-A-Heisei 1-3
No. 8628, the production of a vitrified whetstone using diamond superabrasives also requires 900
It is performed under a nitrogen atmosphere at a high temperature of ° C. This is because the binder for the conventional vitrified grinding wheel is 720
This is because a sintering temperature considerably higher than ℃ was required.

Therefore, in the production of the conventional vitrified grinding wheel, a high temperature is required, so that the energy cost is increased and a long sintering operation time is required. Further, an apparatus and operation for controlling the atmosphere during sintering are required, and the sintering operation is complicated. For this reason, it has been difficult to reduce the production cost of the grindstone.

Therefore, the present invention requires a reducing atmosphere or an inert atmosphere even when sintering a diamond superabrasive, which is extremely important and widely used as a superabrasive for a vitrified grindstone, without oxidizing it. To reduce energy costs, reduce sintering time, simplify sintering work, and reduce costs. And to provide a vitrified grinding wheel.

[0006] In particular, the present invention seeks to achieve the above object based on an improvement in a binder for a vitrified grinding wheel.

[0007]

According to the present invention SUMMARY OF], as to achieve the above object, the following composition SiO _2: 47 to 53 parts by weight Al ₂ O _3: 17~23 parts by weight B ₂ O ₃ : 9-15 parts by weight (CaO + MgO): 6~14 parts by weight _{(K 2 O + Na 2 O} + Li 2 O): and having from 4 to 16 parts by weight, vitrified abrasive binders, is provided.

In one embodiment of the present invention, the composition contains 3 to 7 parts by weight of CaO, 3 to 7 parts by weight of MgO, 1 to 5 parts by weight of K ₂ O, and ₂ to 5 parts by weight of Na ₂ O. comprising 6 parts by weight, including from 1 to 5 parts by weight of the Li ₂ O.

According to the present invention, at least one of diamond superabrasives, cubic boron nitride superabrasives and general abrasives is used as a binder for the vitrified grinding wheel to achieve the above objects. 680-720 ° C using
And a method for producing a vitrified grindstone.

In one embodiment of the present invention, the general abrasive grains are silicon carbide abrasive grains or alumina abrasive grains.

According to the present invention, at least one of diamond super-abrasive grains, cubic boron nitride super-abrasive grains and general abrasive grains is used as a binder for the vitrified grinding wheel. A vitrified grindstone characterized by being bonded by using

In one embodiment of the present invention, the diamond superabrasive grains and at least one of the cubic boron nitride superabrasive grains and the general abrasive grains are bonded using the above vitrified grinding wheel binder.

In one embodiment of the present invention, the diamond superabrasive grains, the cubic boron nitride superabrasive grains, and the general abrasive grains have a particle size in the range of # 60 to # 1000.

In one embodiment of the present invention, the total volume ratio of the diamond superabrasive grains, cubic boron nitride superabrasive grains and general abrasive grains is 35 to 55%, and the volume ratio of the binder is 13 to 55%. 30%, and the pore volume ratio is 20 to 40%.

[0015]

Embodiments of the present invention will be described below.

In the binder for vitrified grinding wheels of the present invention, the content of SiO ₂ is 47 to 53 parts by weight, preferably 48 to 52 parts by weight. If the content of SiO ₂ is too low, the bonding strength tends to decrease. In addition, Si
If the O ₂ content is too high, a high sintering temperature is required for sufficient sintering, and the object of the present invention tends to be difficult to achieve.

In the binder for a vitrified grinding wheel of the present invention, the content of Al ₂ O ₃ is 17 to 23 parts by weight, preferably 18 to 22 parts by weight. If the content of Al ₂ O ₃ is too low, the stability of the binder after sintering tends to decrease. On the other hand, if the content of Al ₂ O ₃ is too high, the melt viscosity tends to increase, and the wettability with abrasive grains tends to decrease.

In the binder for a vitrified grinding wheel of the present invention, the content of B ₂ O ₃ is 9 to 15 parts by weight, preferably 10 to 14 parts by weight. If the content of B ₂ O ₃ is too low, a high sintering temperature is required for sufficient sintering, which tends to make it difficult to achieve the object of the present invention. On the other hand, if the content of B ₂ O ₃ is too high, the melt viscosity tends to decrease, the fluidity increases, and the bonding strength tends to decrease.

In the binder for a vitrified grinding wheel of the present invention, the content of (CaO + MgO) is 6 to 14 parts by weight, preferably 8 to 12 parts by weight. (CaO + M
If the content of gO) is too low, a high sintering temperature is required for sufficient sintering, which tends to make it difficult to achieve the object of the present invention. On the other hand, if the content of (CaO + MgO) is too high, the melt viscosity is lowered, the fluidity is increased, the abrasive grain holding power is reduced, the brittleness is reduced, and the impact resistance tends to be reduced. From the viewpoint of the stability of the binder after sintering, it is preferable to use both CaO and MgO, in which case,
The content of CaO and the content of MgO in the binder are:
In each case, the amount is preferably 3 to 7 parts by weight.

The binder for vitrified grinding wheels of the present invention
And (K_Two O + Na_Two O + Li _Two O) content of 4
To 16 parts by weight, preferably 7 to 13 parts by weight.
(K _Two O + Na_Two O + Li_Two O) content is too low
High sintering temperature is required for sufficient sintering,
It tends to be difficult to achieve the objects of the present invention. Also,
(K_Two O + Na_Two O + Li_Two O) content is too high
Increases the coefficient of thermal expansion, causing stress concentration at the interface with the abrasive grains.
It is easy to break and break easily.
The difference in the tension coefficients tends to increase and the bonding force tends to decrease.
K_Two O, Na_Two O and Li_Two O indicates the safety of the binder after sintering.
From a qualitative viewpoint, it is preferable to use all three.
In the case, K in the binder_Two O content and Li_Two Including O
The amount is 1 to 5 parts by weight of Na_Two O content is 2 ~
Preferably it is 6 parts by weight.

The above SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , C
Each of aO, MgO, K ₂ O, Na ₂ O, and Li ₂ O is used as a raw material in the production of glass or the like, and uses a raw material having the same form as that in that case. be able to. Then, the above components are mixed in a desired ratio, fired at a high temperature, vitrified, and pulverized to obtain a binder.

The binder for a vitrified grinding wheel of the present invention having the above composition can produce a good vitrified grinding wheel even if the temperature at the time of sintering after mixing with abrasive grains is 720 ° C. or less. Can be. Sintering temperature is 680 ℃
It is preferable that it is above. The vitrified grindstone obtained in this manner exhibits a grinding performance equal to or higher than that of a conventional vitrified grindstone manufactured by high-temperature sintering using a conventional vitrified grindstone binder.

The abrasive used in combination with the binder of the present invention as described above may be any of diamond super-abrasives, CBN super-abrasives and general abrasives. Can also be used. Conventional abrasives such as SiC abrasives and Al ₂ O ₃ abrasives can be used as the general abrasives. The particle size of these superabrasive grains and general abrasive grains is, for example, in the range of # 60 to # 1000.

In the vitrified grinding wheel manufactured using the binder of the present invention as described above, the total volume ratio of all the abrasive grains is, for example, 35 to 55%, and the volume ratio of the binder is, for example, 13 to 55%.
30%, and the pore volume ratio is, for example, 20 to 40%.

Since the binder of the present invention can be sintered at a temperature of 720 ° C. or less, particularly in the production of a diamond superabrasive vitrified grindstone, a diamond superabrasive is required without requiring a reducing atmosphere or an inert atmosphere. It is possible to work in the air with a low-cost device configuration without oxidizing the abrasive grains. Furthermore, since the temperature required for sintering can be relatively low, energy costs can be reduced and sintering time can be reduced, and sintering can be simplified to produce diamond superabrasive vitrified wheels at low cost. It is possible to do.

Hereinafter, specific examples and comparative examples of the present invention will be described.

Example 1 : The following composition as a binder: SiO ₂ : 50 parts by weight Al ₂ O ₃ : 20 parts by weight B ₂ O ₃ : 12 parts by weight CaO: 5 parts by weight MgO: 5 parts by weight K ₂ O: 3 Parts by weight Na ₂ O: 4 parts by weight Li ₂ O: 3 parts by weight
These are mixed together with a solvent, and a disc-shaped aluminum substrate (outer diameter 200 mm, thickness 20 mm,
It was shaped into a fan-shaped segment that could be applied on the outer peripheral surface (inner diameter: 50 mm), kept in an electric furnace at a maximum temperature of 700 ° C. for 5 hours in the atmosphere in the air, and completed the sintering operation in a required time of 50 hours. The fan-shaped segment grindstone thus obtained was joined on the outer peripheral surface of the disc-shaped aluminum substrate to form a grinding grindstone layer having a thickness (radial dimension) of 3 mm, thereby producing a grinding wheel.

The volume ratio of the grinding wheel layer of this grinding wheel was as follows: diamond superabrasives: 46% by volume Binder: 18% by volume Pores: 36% by volume

The grinding wheel obtained as described above is mounted on a horizontal axis surface grinder, using alumina porcelain as a work material, while supplying a water-soluble grinding fluid (solble), by a plunge cut grinding method. Wheel peripheral speed 1800m /
min, table speed 15m / min, grinding width 5mm,
A grinding test was performed at a cut of 20 μm.

As a result, the grinding ratio was 100, and the current consumption of the grinding machine (current value per 1 mm of grinding width, the increase or decrease corresponds to the increase or decrease of the grinding resistance) 1.00 Amp / m
m, good grinding was possible, and the bending strength of the grindstone layer was good, so that it could be sufficiently practically used.

Example 2 : SiO ₂ , A in binder composition
l ₂ O ₃ , B ₂ O ₃ , CaO, MgO, K ₂ O, Na ₂
O and Li ₂ O are represented by the following plural values, respectively: SiO ₂ (parts by weight): 47, 48, 52, 53 Al ₂ O ₃ (parts by weight): 17, 18, 22, 23 B ₂ O ₃ (parts by weight) ): 9, 10, 14, 15 CaO (parts by weight): 3, 4, 6, 7 MgO (parts by weight): 3, 4, 6, 7 K ₂ O (parts by weight): 1, 2, 4, 5 Na ₂ O (parts by weight): 2, 3, 5, 6 Li ₂ O (parts by weight): 1, 2, 4, except that was varied was performed in the same manner as in example 1. The volume ratio configuration of the grinding wheel layer of the grinding wheel was the same as in Example 1 above.

As a result of a grinding test of the grinding wheels manufactured for all the combinations, good grinding was possible, and the bending strength of the grindstone layer was good, so that the wheels could be sufficiently put to practical use.

Example 3 Using the same binder as used in Example 1, diamond superabrasive grains # 14 as abrasive grains
0, CBN super abrasive # 140, SiC abrasive # 150 and A
Using l ₂ O ₃ abrasive grains # 150 in a combination as shown in Table 1 below, the volume ratio composition of the grinding wheel layer is as shown in Table 1, and the work materials SUJ-2 and SKD as work materials -11
Example 1 except that (hardened), SKH-9 (hardened) and alumina porcelain were used as shown in Table 1.
Was performed in the same manner as described above.

Table 1 shows the results of the grinding test together with the work material.

[0035]

[Table 1] Here, DIA = diamond super abrasive # 140 CBN = CBN super abrasive # 140 SiC = SiC abrasive # 150 Al ₂ O ₃ = Al ₂ O ₃ abrasive # 150 = work material SUJ-2 = work material SKD-11 (hardened) = Work material SKH-9 (hardened) = Workpiece alumina porcelain.

As described above, good grinding is possible in each case.
The bending strength of the grindstone layer was also good and could be sufficiently used practically.

Example 4 The procedure was the same as in Examples 1 to 3, except that the maximum temperature during sintering was 680 ° C. and 720 ° C.

As a result, the maximum temperature during sintering was 680 ° C. and 7
In each case at 20 ° C., the obtained grindstone had good grinding performance, and the bending strength of the grindstone layer was good, so that it could be sufficiently practically used.

Example 5: As abrasive grains, SiC abrasive grains # 15
0, only Al ₂ O ₃ abrasive grain # 150 alone, and combinations thereof, except that the above examples 1 to 4 were used.

As a result, in each case, the obtained grindstone had good grinding performance, and the bending strength of the grindstone layer was good, so that it could be sufficiently practically used.

Comparative Example 1 : The following composition as a binder: SiO ₂ : 72 parts by weight Al ₂ O ₃ : 8 parts by weight B ₂ O ₃ : 8 parts by weight CaO: 2 parts by weight BaO: 3 parts by weight Other oxides Total: 2 parts by weight, diamond super abrasive #
These are mixed together with a solvent, and a disc-shaped aluminum substrate (outer diameter 200 mm, thickness 20 mm,
It was shaped into a fan-shaped segment that could be applied on the outer peripheral surface (inner diameter: 50 mm), held in an electric furnace at a maximum temperature of 1030 ° C. for 5 hours in the atmosphere, and completed the sintering operation in a required time of 60 hours. The fan-shaped segment grindstone thus obtained was joined on the outer peripheral surface of the disk-shaped aluminum substrate, and a grinding wheel layer having a thickness of 3 mm was formed to produce a grinding wheel.

The volume ratio of the grinding wheel layer of this grinding wheel was as follows: diamond superabrasives: 46% by volume Binder: 18% by volume Pores: 36% by volume

The grinding wheel obtained as described above was mounted on a horizontal axis surface grinder, and a grinding test was performed in the same manner as in Example 1 using alumina porcelain as a work material.

As a result, the grinding ratio was 60, and the current consumption of the grinding machine was 0.80 Amp / mm.

Comparative Example 2 A grinding wheel was produced in the same manner as in Comparative Example 1, except that CBN superabrasive # 140 was used instead of diamond superabrasive.

The volume ratio of the grinding wheel layer of this grinding wheel was as follows: CBN superabrasives: 50% by volume Binder: 14% by volume Pores: 36% by volume

The grinding wheel obtained as described above was mounted on a horizontal axis surface grinder, and a grinding test was performed in the same manner as in Comparative Example 1 using SKH-9 (hardened) as a work material.

As a result, the grinding ratio was 265, and the current consumption of the grinding machine was 1.20 Amp / mm.

From the results of the above Examples and Comparative Examples, it was found that using the binder for a vitrified grinding wheel of the present invention, 680
Vitrified grinding wheel manufactured by sintering at low temperature of ~ 720 ° C has grinding performance comparable to that of vitrified grinding wheel manufactured by sintering at a high temperature of about 1000 ° C using a conventional binder. It can be seen that they have sufficient practical use.

[0050]

As described above, by using the binder for the vitrified grinding wheel of the present invention, the diamond super-abrasive grain, which is very important and widely used as the super-abrasive grain for the vitrified grinding wheel, is sintered without oxidation. In this case, a reducing atmosphere or an inert atmosphere is not required, so that the operation can be performed with a low-temperature apparatus configuration at a low temperature of 720 ° C. or less in the air, energy costs are reduced, and sintering operation time is reduced. Is reduced, the sintering operation is simplified, and a vitrified grinding wheel is provided at low cost.

Claims (9)

[Claims] 1. A following composition SiO _2: 47 to 53 parts by weight Al ₂ O _3: 17~23 parts by weight B ₂ O _3: 9~15 parts by weight (CaO + MgO): 6~14 parts by weight (K ₂ O + Na ₂ O + Li ₂ O): A binder for a vitrified grinding wheel, comprising 4 to 16 parts by weight. 2. The method according to claim 2, wherein the CaO is contained in an amount of 3 to 7 parts by weight,
comprises 3-7 parts by weight of gO, the K ₂ O and contains from 1 to 5 parts by weight, the Na ₂ O and containing from 2 to 6 parts by weight, characterized in that it comprises the Li ₂ O 1-5 parts by weight, The binder for a vitrified grinding wheel according to claim 1. 3. The method according to claim 1, wherein at least one of diamond superabrasive grains, cubic boron nitride superabrasive grains and general abrasive grains is used.
2. A method for producing a vitrified grinding wheel, comprising sintering at 680 to 720 ° C. using the binder for a vitrified grinding wheel according to any one of 2. 4. The method for producing a vitrified grinding wheel according to claim 3, wherein the general abrasive grains are silicon carbide abrasive grains or alumina abrasive grains. 5. The method according to claim 1, wherein at least one of diamond superabrasive grains, cubic boron nitride superabrasive grains and general abrasive grains is used.
3. A vitrified grinding wheel, characterized by being bonded using the vitrified grinding wheel binder according to any one of 2. 6. The method according to claim 1, wherein the diamond super abrasive is at least one of cubic boron nitride super abrasive and general abrasive.
A vitrified grinding wheel, characterized by being bonded using the vitrified grinding wheel binder according to any one of claims 1 to 2. 7. The vitrified grinding wheel according to claim 5, wherein said general abrasive grains are silicon carbide abrasive grains or alumina abrasive grains. 8. The method according to claim 5, wherein the diamond superabrasive grains, the cubic boron nitride superabrasive grains and the general abrasive grains have a particle size in the range of # 60 to # 1000. The described vitrified whetstone. 9. The total volume ratio of the diamond superabrasive grains, the cubic boron nitride superabrasive grains and the general abrasive grains is 35 to 55%, the volume ratio of the binder is 13 to 30%, and the pores are The vitrified grindstone according to any one of claims 5 to 8, wherein a volume ratio of the vitrified grindstone is 20 to 40%.