JPH05247449A - Grinding wheel - Google Patents

Abstract

PURPOSE:To provide a grinding wheel which gives a very good finished (ground) surface without decreasing the grinding efficiency. CONSTITUTION:A grinding wheel is provided wherein the outer surface of each hollow grain 12 is covered with many auxiliary abrasive grains 20 which have diameters lower than those of the main abrasive grains 10 and are bonded to each other through glass 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding wheel, and in particular,
The present invention relates to a grinding wheel formed by bonding abrasive grains and hollow grains with a binder.

[0002]

2. Description of the Related Art A grinding wheel is composed of three elements, an abrasive grain, a binder, and pores, and the pores function as chip pockets for removing cutting powder. And from the past,
When performing a grinding operation under severe grinding conditions in which grinding burn is likely to occur, a porous grinding wheel with a reduced number of abrasive grains and increased pore volume is used.

[0003]

However, in the conventional porous grinding wheel as described above, the number of working cutting edges decreases as the number of abrasive grains decreases, so that the original abrasive grains are obtained. There is a drawback that the desired machined surface roughness cannot be obtained. Further, when the number of abrasive grains decreases, the interval between the abrasive grains becomes wider, the binding force between the abrasive grains due to the binder decreases, and the load per abrasive grain on the ground surface increases, so that the grinding stone is realigned. At the time of grinding or during grinding, the abrasive grains themselves tend to fall off, which reduces the number of abrasive grains on the ground surface, and thus the number of working cutting edges, making it impossible to obtain the machined surface roughness that is originally obtained by the above-mentioned abrasive grains. is there.

On the other hand, as described in, for example, Japanese Patent Application Laid-Open No. 62-251077 filed by the applicant of the present invention, the grinding wheel contains hollow particles and the hollow particles are contained in the hollow particles. If the pores are secured, the binding force between the abrasive grains due to the binder can be obtained appropriately, so that the abrasive grains themselves fall off during dressing and grinding of the grinding stone as compared with the conventional porous grinding stone. It can be suppressed suitably and a suitable processed surface roughness can be obtained. However, even if the hollow particles are contained in this way, the number of working cutting edges of the grinding wheel does not increase remarkably, so that the finished surface roughness is better than the original surface roughness expected from the particle size of the abrasive particles. I didn't get a face. In order to obtain a better finished surface, there is no choice but to separately provide a finishing step using a grindstone composed of abrasive grains having a smaller diameter than the above-mentioned abrasive grains, which complicates the process and work and reduces the grinding efficiency. Is hard to avoid.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a grinding wheel capable of obtaining a better finished surface (working surface) without lowering the grinding efficiency. To provide.

[0006]

Means for Solving the Problems As a result of various studies conducted by the present inventor against the circumstances described above, when the peripheral wall of hollow particles is constituted by abrasive grains having a diameter smaller than that of the main abrasive grains, only the main abrasive grains are formed. It has been found that while maintaining the same grinding efficiency as the above, a finished surface that is significantly better than the machined surface roughness originally obtained by the main abrasive grain can be obtained.

The present invention was made on the basis of such findings, and the gist of the invention is a grinding wheel formed by combining a main abrasive grain and hollow grains with a binder.
The peripheral wall of the hollow particles is configured by bonding a large number of sub-abrasive particles having a smaller diameter than the main abrasive particles.

As the sub-abrasive grains, those having a grain size equal to or smaller than half the grain size of the main abrasive grains are preferably used. The sub-abrasive grains are preferably 0.5 μm.
A material having a particle size of ˜40 μm is used. Also,
The hollow particles are preferably 2 times the particle size of the main abrasive particles.
Those having a particle size of 1 to 2 times the particle size are used.

[0009]

As described above, according to the grinding wheel of the present invention, since the peripheral wall of the hollow particles is composed of a large number of sub-abrasive particles having a diameter smaller than that of the main abrasive particles, the main particles are bonded to each other. In addition to grinding with abrasive grains, it is also possible to grind or polish with the above-mentioned sub-abrasive grains. As a result, it is possible to obtain a finished surface that is significantly better than the machined surface roughness that should be originally obtained by the main abrasive grains, without reducing the grinding efficiency by separately providing a finishing process.

In addition to the fact that the pores are secured in the hollow grains, the bonding force between the main abrasive grains due to the binder is preferably obtained, and in addition, the presence of the sub-abrasive grains causes the main abrasive grains 1 on the ground surface.
By suitably reducing the load per piece, it is possible to more suitably suppress the main abrasive grains themselves from falling off during dressing and grinding. This makes it possible to relatively reduce the number of main abrasive grains in the grinding wheel, and by reducing the number of main abrasive grains in this way, the dressing property of the grinding wheel can be improved and the main abrasive grains can be compared. When it is relatively expensive, the cost of the grinding wheel can be suitably reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

First, press-molding was carried out according to the respective formulations of Example 1, Example 2 and Comparative Example in Table 1, and each press-molded product was baked at 950 ° C. for 5 hours to give an outer diameter of 305 mm and a thickness. A disk-shaped vitrified grindstone having a diameter of 15 mm and a central hole diameter of 76.2 mm was prepared. The unit of numerical values in Table 1 is the capacity part.

FIG. 1 is an enlarged cross-sectional view showing a part of a vitrified grindstone prepared by blending the above-mentioned first and second embodiments. In the figure, 10 is a main abrasive grain, 12 is a hollow grain having pores 14 inside, 16 is a vitrified bond as a binder, and 18 is a pore. Main abrasive grain 10
Is, for example, cubic boron nitride (hereinafter abbreviated as CBN)
It consists of super abrasive grains consisting of
It has a granularity in the order of a number. The hollow particles 12 are
For example, it has a particle size approximately the same as the main abrasive grain 10,
On the peripheral wall of the hollow grain 12, a large number of sub-abrasive grains 20 are formed on the glass 2.
The two are connected to each other. Sub abrasive grain 20
Is composed of, for example, superabrasive grains made of CBN similarly to the main abrasive grain 10, and is sufficiently smaller than the main abrasive grain 1.
It has a particle size of about 5 μm. The hollow particles 12 are produced, for example, by a so-called melt-spraying method based on the fact that a glass melt mixed with the sub-abrasive particles 20 is caused to flow out and high-pressure air is blown to the outflowing liquid. The grain 20 has a composition of 10.0 parts by volume, the glass 22 has a composition of 3.0 parts by volume, and the pores 14 have a composition of 87.0 parts by volume. In addition, in FIG. 1, 24 shows a cutting surface. Further, in the comparative example, instead of the hollow particles 12, hollow particles made of only alumina and having substantially the same diameter as the hollow particles 12 were used. Further, as can be seen from Table 1, the number of main abrasive grains 10 of Example 1 is substantially the same as that of the comparative example, but the main abrasive grains 1 of Example 2 are
The number of 0's is reduced considerably more than in the comparative example.

[0014]

[Table 1]

Next, the vitrified grindstones of the above-mentioned respective examples are each subjected to surface grinding to grind the grinding ratio (grinding amount of work material / reduction of grindstone), power consumption, and machined surface roughness of work material. The number of working cutting edges of the main abrasive grains after grinding was examined in addition to the relation with the grinding amount of the material. The examination results are shown in FIGS. 2 to 5 for the example 1 together with the comparative example, and for the example 2 are shown in FIGS. 6 to 9 together with the comparative example. Grinding conditions are grinding wheel peripheral speed 1600m / min
, Table feed speed is 20m / min, depth of cut is 10μm
/ Pass, the work material is SKH51, the size of the work material is 3
It is 00 mm x width 10 mm. In the tables shown in FIGS. 5 and 9, the number of working cutting edges is shown as an index with the number of working cutting edges of the grindstone of the comparative example being 100.

First, according to the grindstone of Example 1, it is considered that the power consumption is substantially the same as that of the comparative example and the sharpness is substantially the same as that of the comparative example in FIG. 3, but the grinding ratio in FIG. It is higher than that and the life of the grindstone is longer,
In, the machined surface roughness is significantly improved compared to the comparative example. Further, in FIG. 5, the number of working cutting edges after grinding is significantly larger than that in the comparative example, and the main abrasive grain 1 during dressing and grinding
It shows that the number of 0 itself dropped out. In addition to grinding with the main abrasive grain 10, a large number of sub-abrasive particles 20 on the peripheral wall of the hollow grain 12
It is considered that the machined surface roughness can be greatly improved as compared with the comparative example, because the finishing step is not separately provided and the grinding efficiency is not decreased by the fact that the grinding or polishing can be performed by the method. In this case, the fact that the main abrasive grains 10 themselves do not fall off is considered to have contributed to the improvement of the machined surface roughness.

Next, according to the grindstone of Example 2, the number of working cutting edges after grinding is substantially the same as that of the comparative example in FIG. 9, and the grinding ratio is substantially the same as that of the comparative example in FIG. Although it is considered that the life is almost the same as that of the comparative example, the power consumption is lower than that of the comparative example in FIG. 7, and the sharpness is considered to be improved as compared with the comparative example. Further, in FIG. 8, the processed surface roughness is improved as compared with the comparative example. That is, as described above, the number of the main abrasive grains 10 is significantly reduced as compared with the comparative example because the main abrasive grains 10 themselves are less likely to fall off during dressing or grinding and the sub-abrasive grains 20 are also ground or polished. Nevertheless, compared with the grindstone of the comparative example, the durability is almost the same and the sharpness and the processed surface roughness are improved.

Further, according to the grindstone of Example 2, Example 1
Further, since the number of main abrasive grains 10 is reduced as compared with the comparative example, there is an advantage that the dressing property of the grindstone can be further improved as compared with Example 1 and the comparative example, and the main abrasive grains composed of superabrasive grains. Since 10 is relatively expensive, there is an advantage that the cost of the grindstone can be reduced at least as compared with the first embodiment.

Although the above description is based on an embodiment of the present invention, the present invention can be implemented in other modes.

For example, in the above embodiment, the vitrified bond 1 is used as the binder for the main abrasive grains 10 and the hollow grains 12.
Although the vitrified grindstone using No. 6 has been described, the present invention can also be applied to an elastic grindstone formed by bonding the main abrasive grains and the hollow grains with a resin binder or a rubber binder.

Further, in the above-mentioned embodiment, the glass 22 is used as the binder for bonding the sub-abrasive grains 20 to each other, but it is not always necessary and, for example, ceramics can be used, or the above-mentioned elastic material can be used. In the grindstone, a resin binder or a rubber binder may be used as the binder for the sub-abrasive grains.

Further, in the above embodiment, the hollow particles 12 are manufactured by the melt spraying method, and the peripheral wall of the hollow particles 12 is composed of the sub-abrasive particles 20 and the glass 22, but this is not always necessary. For example, the hollow particles of the present invention can be manufactured by coating the surface of a hollow substance such as ceramics with a sub-abrasive grain and a binder, respectively, and sintering the hollow grains. Alternatively, the hollow grains of expanded polystyrene spheres having a low melting point can be produced. Sub-abrasive particles and a binder are coated on the surface of a core material made of a substance, respectively, and the core material is pyrolyzed by heating to make the core material hollow, and then the sub-abrasive particles and the binder are sintered. The hollow particles of the present invention can be produced by a core material decomposition method, and further, the hollow particles of the present invention can be produced by a so-called heat foaming method using a foaming agent.

Further, in the above embodiment, both the main abrasive grain 10 and the sub-abrasive grain 20 are made of superabrasive grains made of cubic boron nitride, but other than superabrasive grains such as diamond and others. The main abrasive grains and the sub-abrasive grains may be made of different materials from each other.

Further, in the above-mentioned embodiment, the hollow particles 12 have the same particle size as the main abrasive particles 10, but as the hollow particles, for example, one half to two times the particle diameter of the main abrasive particles is used. The effect of the present invention can be preferably obtained if the particles having the same particle diameter are used.

Further, in the above embodiment, the number of the sub-abrasive grains 20 is 15
A particle having a particle size of about μm is used, but a particle having a particle size of, for example, ½ or less of the particle size of the main abrasive or a particle size of, for example, about 0.5 μm to 40 μm is used as the sub-abrasive. The effect of the present invention can be preferably obtained if the one having the above is used.

In addition, it is a matter of course that the present invention can be implemented in variously modified modes without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an enlarged part of a grinding wheel that is an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a grinding ratio and a grinding amount by the grinding wheel of the first embodiment of the present invention, and is a diagram also showing a comparative example.

FIG. 3 is a diagram showing the relationship between the power consumption and the grinding amount by the grinding wheel of the first embodiment, together with a comparative example.

FIG. 4 is a diagram showing a relationship between a processed surface roughness and a grinding amount by the grinding wheel of the first embodiment, and is also a diagram showing a comparative example together.

FIG. 5 is a table showing the number of working cutting edges after grinding of the grinding wheel of the first embodiment together with a comparative example in an index.

FIG. 6 is a diagram showing a relationship between a grinding ratio and a grinding amount by a grinding wheel of a second embodiment of the present invention, together with a comparative example.

FIG. 7 is a diagram showing the relationship between the power consumption and the grinding amount by the grinding wheel of the second embodiment, together with a comparative example.

FIG. 8 is a diagram showing a relationship between a processed surface roughness and a grinding amount by the grinding wheel of the second embodiment, and is also a diagram showing a comparative example together.

FIG. 9 is a table showing the number of working cutting edges after grinding of the grinding wheel of the second embodiment together with a comparative example in an index.

[Explanation of symbols]

 10 Main Abrasive Grain 12 Hollow Grain 16 Vitrified Bond (Binder) 20 Sub Abrasive Grain

Claims (1)

[Claims] 1. A grinding wheel comprising a main abrasive grain and hollow grains bonded together using a binder, wherein a plurality of sub-abrasive grains having a peripheral wall of the hollow grains smaller than the main abrasive grain are bonded to each other. A grinding wheel characterized by being constituted by the above.