JP2003117835A - Grinding wheel with superabrasive grain of vitrified bond type - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding wheel with superabrasive grains capable of enhancing the sharpness in cutting by increasing the brittleness of a noncrystal glass bonding agent and thereby enlarging the amount of the abrasive grains protruding out from the bonding agent at the grinding surface. SOLUTION: The vitrified bond type grinding wheel is structured so that superabrasive grains 14 are bonded by the noncrystal glass binding agent 15 in which particles 16 of aluminum nitride are included. These particles make reaction with the noncrystal glass bonding agent under the baking process, and bubbles 19 are generated at the interface between the two, which leads to heightening of the brittleness of the bonding agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vitrified bond superabrasive grindstone in which superabrasive grains such as CBN (cubic boron nitride) and diamond are bonded with an amorphous glass binder.

[0002]

2. Description of the Related Art Conventionally, a low-concentration vitrified bond superabrasive grain grindstone is formed by mixing alumina grains and the like with superabrasive grains such as CBN and diamond as an aggregate and combining them with a glass binder.

[0003]

In the above-mentioned conventional grindstone, the brittleness of the glass binder is not sufficient, and the binder on the grinding surface of the grindstone is not easily scraped by chips or the like. However, the amount of the protrusions to the outside from the glass binder covering the outer periphery is small. Therefore, such a grindstone cannot be ground with a sharp cutting edge, and the amount of heat generated increases due to the contact between the cutting chips and the vitrified bond.
In particular, oil-based coolant has the advantage that it can be recycled and is environmentally friendly, but it does not cool as well as water-soluble coolant, so heat generation during grinding is suppressed in order to suppress the temperature rise of the workpiece. It was desired to keep the amount down.

The present invention is to meet such a demand, and to improve the sharpness of the grindstone by increasing the brittleness of the glass binder to increase the amount of the superabrasive grains protruding from the binder to the outside on the ground surface. .

[0005]

In order to solve the above problems, the structural feature of the invention according to claim 1 is that superabrasive grains are bonded with an amorphous glass binder mixed with aluminum nitride particles. is there.

A feature of the invention according to claim 2 is that in the vitrified bond superabrasive grain grindstone according to claim 1, the superabrasive grains are CBN abrasive grains.

A characteristic feature of the invention according to claim 3 is that in the vitrified bond superabrasive grindstone according to claim 1 or 2, the amorphous glass binder is a borosilicate glass binder.

According to a fourth aspect of the present invention, there is provided a vitrified bond superabrasive grindstone according to any one of the first to third aspects, wherein the mixing ratio of the amorphous glass binder and the aluminum nitride particles is That is 70:30 to 55: 45% by volume.

According to a fifth aspect of the present invention, in the vitrified bond superabrasive grindstone according to any one of the first to fourth aspects, the aluminum nitride particles have an average particle diameter of 10 to 40 μm. Is.

[0010]

In the invention according to claim 1 configured as described above, since the superabrasive grains are bonded by the amorphous glass binder mixed with the aluminum nitride particles, the aluminum nitride particles and the amorphous glass bond are bonded. The agent reacts with the agent during firing, and bubbles are generated at the interface between the two, increasing the brittleness of the binder. Therefore, the amount of superabrasive grains protruding from the binder by the cutting chips scraping off the binder during grinding increases, and the sharpness of the grindstone is improved, so that heat generation due to contact between the chips and the binder is suppressed.

In the invention according to claim 2 configured as described above, since the superabrasive grains are CBN abrasive grains, in addition to the effect of the invention according to claim 1, a chemically stable CBN abrasive grain is used. It is possible to grind steel parts such as automobile parts with high accuracy and at low cost.

In the invention according to claim 3 configured as described above, since the amorphous glass binder is the borosilicate glass binder, gas is generated by a chemical reaction at the interface with the aluminum nitride particles during firing. It is easy and the brittleness of the binder can be easily controlled.

In the invention according to claim 4 configured as described above, the mixing ratio of the amorphous glass binder and the aluminum nitride particles is set to 70:30 to 55: 45% by volume.
If the mixing ratio of aluminum nitride is 30% or less, the shape of the grindstone cannot be maintained before or during the baking, and the corners will be sagging, and if it is 45% or more, the solid component becomes excessive and the binder is not formed. It becomes too hard, and the amount of heat generated during grinding increases. In the invention according to claim 4, since the mixing ratio of the aluminum nitride particles is set to 30 to 45% by volume, a grindstone having an appropriate hardness can be fired into a desired shape.

In the invention according to claim 5 configured as described above, the average particle diameter of the aluminum nitride particles is 10
˜40 μm. If the average particle size of the aluminum nitride particles is too small, the reaction area between the amorphous glass binder and the aluminum nitride particles becomes too large, and the amount of gas generated at the interface between the two becomes too large and the binder becomes too brittle. On the other hand, if the average particle size of aluminum nitride is too coarse, the reaction area becomes too small, and the gas generation is insufficient, so that sufficient brittleness cannot be obtained. In the invention according to claim 5, the average particle diameter is 10 to 4
Since the thickness is 0 μm, the strength can be sufficiently maintained, the binder can be appropriately brittle, and heat generation during grinding can be suppressed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, a grinding wheel 11 is constructed by bonding a plurality of arc-shaped grinding wheels 13 having a thickness of 5 to 10 mm to an outer peripheral surface of a disk-shaped base body 12 formed of metal such as iron or aluminum. There is. The grindstone 13 is composed of superabrasive grains 14 such as CBN and diamond bonded by an amorphous glass binder 15 such as borosilicate glass. In the amorphous glass binder 15, aluminum nitride (AlN) particles 16 are aggregates. It is mixed as. The amorphous glass binder 15 mixed with the aluminum nitride particles 16 covers the outer periphery of the superabrasive grains 14 and bridges and bonds between the adjacent superabrasive grains 14 to form a large number of pores 18 between the bridge portions 17. There is. The average particle diameter of the aluminum nitride particles 16 is 10 to 40 μm, and the mixing ratio of the amorphous glass binder 15 and the aluminum nitride particles 16 is 7
It is 0: 30% by volume to 55: 45% by volume. If the mixing ratio of the aluminum nitride particles 16 is 30% or less, the shape of the grindstone 13 cannot be maintained before or during firing,
The corners are dull. When the mixing ratio is 45% or more, the solid component becomes excessive, the amorphous glass binder 15 containing the aluminum nitride particles 16 becomes too strong and hard, and the amount of heat generated during grinding increases. In the vitrified bond superabrasive grindstone 13 according to the present invention, the grindstone 13 having an appropriate hardness is fired into a desired shape by setting the mixing ratio of aluminum nitride to 30 to 45% by volume.

A large number of small bubbles 19 are formed on the side of the amorphous glass binder 15 at the interface between the amorphous glass binder 15 and the aluminum nitride particles 16. The bubble 19 is
When the superabrasive grains, the aluminum nitride particles 16 and the amorphous glass binder 15 are mixed and shaped into an arc, and the arc shaped body is fired to form the grindstone 13, the aluminum nitride particles 16 and the amorphous glass are used. It is generated by chemically reacting with the binder 15 during firing to generate gas at the interface between the two. When borosilicate glass is used as the non-crystalline glass binder 15, gas is easily generated due to a chemical reaction at the interface with the aluminum nitride particles 16 during firing, and the brittleness of the binder 15 can be easily controlled.

Next, the operation of the vitrified bond superabrasive grindstone 13 according to the present invention will be described. The grindstone 11 is rotatably driven by being supported on the grindstone of the grinder, and the workpiece is sandwiched between the headstock and the tailstock to be rotatably driven, while supplying the coolant between the grindstone 11 and the workpiece. The grindstone base is ground and fed toward the workpiece, and the workpiece is ground by the grindstone 13 bonded to the outer peripheral surface of the grinding wheel 11.

Since the amorphous glass binder 15 has increased brittleness due to the bubbles 19 formed at the interface with the aluminum nitride particles 16, the amorphous glass binder 15 is appropriately scraped off by the chips removed by grinding by the superabrasive grains 14 during grinding. Superabrasive grain 14 is a grindstone 1
In the grinding surface 20 of No. 3, the amount t protruding from the binder 15 to the outside increases. Therefore, the sharpness of the grindstone is improved, and heat generation due to contact between the cutting chips and the amorphous glass binder 15 is suppressed. Further, since the aluminum nitride particles 16 have high thermal conductivity, the amount of heat flowing to the grindstone 13 side in the grinding heat generated during grinding increases, and the temperature rise of the workpiece is suppressed. As is clear from the graph of FIG. 3 showing the relationship between the surface temperature of the workpiece due to grinding and the grinding power, the workpiece surface temperature increases as the grinding power increases in the conventional grindstone. For example, the grinding power is 4.14. The surface temperature of the workpiece is 9
It is 1.8. On the other hand, in the vitrified bond superabrasive grindstone 13 according to the present invention, the surface temperature of the workpiece becomes 72.7 when the grinding power is 4.27, and the temperature rise of the workpiece is suppressed by about 20%. As described above, the grindstone 13 has good sharpness and can suppress the temperature rise of the workpiece. Therefore, the grindstone 13 is particularly suitable for the grinding process using the oil-based coolant, which has a poorer cooling property than the water-soluble coolant. It is possible to grind the workpiece with high accuracy and high efficiency by suppressing the temperature rise of and without grinding burn.

[Brief description of drawings]

FIG. 1 is a view showing a grinding wheel in which a vitrified bond superabrasive grindstone is adhered to the outer periphery of a substrate.

FIG. 2 is a diagram showing a configuration of a vitrified bond superabrasive grain grindstone according to the present invention.

FIG. 3 is a graph showing a relationship between a surface temperature of a workpiece by grinding and grinding power.

[Explanation of symbols]

11 ... Grinding wheel, 12 ... Base, 13 ... Grinding wheel,
14 ... Super abrasive grain, 15 ... Amorphous glass binder, 1
6 ... Aluminum nitride particles, 17 ... Cross-linking part, 1
8 ... Pores, 19 ... Bubbles, 20 ... Ground surface.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryohei Mukai             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. F term (reference) 3C063 AA02 AB03 BB02 BC05 BC09                       BD01 BG01 BG07 FF23

Claims (5)

[Claims] 1. A vitrified bond superabrasive grain grindstone in which superabrasive grains are bonded by an amorphous glass binder mixed with aluminum nitride particles. 2. The vitrified bond superabrasive grindstone according to claim 1, wherein the superabrasive grains are CBN abrasive grains. 3. The vitrified bond superabrasive grindstone according to claim 1, wherein the amorphous glass binder is a borosilicate glass binder. 4. The vitrified bond-based material according to claim 1, wherein a mixing ratio of the amorphous glass binder and aluminum nitride particles is 70:30 to 55: 45% by volume. Abrasive whetstone. 5. The vitrified bond superabrasive grindstone according to claim 1, wherein the aluminum nitride particles have an average particle diameter of 10 to 40 μm.