JPH05192867A - Vitrified bond super head abrasive grain grinding wheel - Google Patents

Abstract

PURPOSE:To provide a super hard abrasive grain grinding wheel capable of grinding at high speed by enhancing the centrifugal rupture strength. CONSTITUTION:A grinding wheel layer 12 comprising a grinding wheel outer layer 12A containing super hard abrasive grains such as CBN and a grinding wheel inner layer 12B containing Al2O3 is brazed to a metallic base 13 by Ti- containing silver braze, for example, to form a brazing layer 14 to firmly join the layer 12 to the base 13; the centrifucal rupture strength of the grinding wheel is greatly enhanced and the efficiency of grinding is enhanced.

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, and particularly, it is devised so as to increase its centrifugal fracture strength.

[0002]

2. Description of the Related Art A superabrasive grindstone using diamond or CBN having a hardness second to that of diamond as an abrasive grain is Al ₂ O ₃
Demand is growing due to features such as longer wheel life and lower grinding force than conventional wheels using SiC or SiC as abrasive grains. Such superabrasive grindstones are classified into several types according to the type of bond that hardens the abrasive grains. Among them, there are vitrified bond grindstones. This vitrified bond superabrasive grain grindstone is obtained by solidifying superabrasive grains by vitrified bond containing oxides such as SiO ₂ , Al ₂ O ₃ , and B ₂ O ₃ . This vitrified bond superabrasive grindstone has high practicality and is in the mainstream because it is easy to tow and dress.

An example of this conventional vitrified bond superabrasive grindstone is shown in FIG. As shown in the figure, a conventional vitrified bond superabrasive grain grindstone 01 does not contain a grindstone outer layer (thickness several mm) 02A containing superabrasive grains such as CBN and superabrasive grains, for example, Al ₂ O ₃ or SiC. It is composed of a grindstone layer 02 composed of a grindstone inner layer (thickness of several mm) 02B containing abrasive grains, and a metal or resin base metal 03, and the grindstone outer layer 02A and the grindstone inner layer 02B of the grindstone layer 02. The same vitrified bond is integrally fired and integrated. Further, the grindstone inner layer 02B and the base metal 04 are adhered to each other by using, for example, a resin adhesive 04 mainly composed of epoxy.

[0004]

By the way, in recent years, in order to improve the grinding efficiency, the peripheral speed of the grindstone has been increased, for example, 150 times that of the conventional peripheral speed (30 m / s).
High-speed grinders exceeding m / s have been put to practical use. However, most of the grindstones used therefor are metal bond or electrodeposition grindstones, and vitrified bond superabrasive grindstones have not been used.

This is because in the conventional vitrified bond superabrasive grindstone, the adhesive force of the adhesive 04 is about 2 k in terms of tensile coefficient.
Since only g / mm ² can be obtained, high-speed rotation (peripheral speed 12
0 m / s), the strength of this part becomes the lowest first, peeling occurs, and the grindstone layer scatters.
This is because high speed grinding of m / s or more cannot be performed.

In view of the above circumstances, it is an object of the present invention to provide a vitrified bond superabrasive grindstone capable of improving centrifugal fracture strength and enabling high speed rotary grinding.

[0007]

The constitution of the vitrified bond superabrasive grindstone according to the present invention which achieves the above-mentioned object is C
A vitrified bond superabrasive grindstone in which superabrasive grains made of BN or diamond are hardened with a vitrified bond, wherein the grindstone layer containing the abrasive grains and a metallic base metal are brazed. .

[0008]

In the vitrified bond superabrasive grindstone having the above structure, since the grindstone layer and the base metal are brazed and bonded, the bonding strength at the interface between the grindstone layer and the base metal is improved, and high-speed rotation grinding is performed. Even if it does, peeling does not occur, enabling high-speed rotary grinding.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a vitrified bond superabrasive grindstone according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic view of a vitrified bond superabrasive grindstone according to this embodiment. As shown in the figure, a vitrified bond superabrasive grain grindstone 11 according to this embodiment is formed by a grindstone layer 12 containing superabrasive grains such as CBN and a metallic base metal 13 by, for example, brazing of silver solder. They are joined via the brazing layer 14.

In this embodiment, the grindstone layer 12 is composed of a CBN grindstone outer layer 12A having a grain size of 80, a concentration of 100, and a thickness of 3 mm, and an Al ₂ O ₃ grindstone inner layer 12B having a grain size of 120 and a thickness of 5 mm. These are fired with the same vitrified bond containing SiO ₂ as a main component. Further, the inner layer 12B of the whetstone of the whetstone layer 12 and the metallic base metal 13
Means that a brazing layer 14 made of silver brazing is formed on the surface 13a of the metallic base metal 13 to firmly bond the two. As the silver solder, silver solder containing 2% Ti (70
%: Ag, 28%: Cn) to form the brazing layer 14.

[0011] brazing strength of the grindstone thus obtained can be obtained of about ^{4kg / mm 2, 1kg / mm} 2 when compared to the strength of the connection of the prior art epoxy adhesive is more than 4 times Will also be higher.

The vitrified bond superabrasive grindstone according to the present embodiment obtained as a result has a significantly improved centrifugal fracture strength, and the peripheral speed of the grindstone can be more than doubled as compared with the conventional one, thereby improving the grinding efficiency. be able to.

On the other hand, there is a difference in the coefficient of thermal expansion between the ceramic-based grindstone layer 12 and the metallic base metal 13, and cracks may occur due to the difference in shrinkage during cooling after brazing and peeling.

In this case, by disposing a metal having a small coefficient of thermal expansion on the outer peripheral surface of the metallic base metal 13 and brazing the metal having a small coefficient of thermal expansion and the grindstone layer 12, the above-mentioned problem of peeling is solved. Bonding with higher strength is possible.

The metallic base metal 13 may be made of a metal having a small coefficient of thermal expansion, but a metal having a small coefficient of thermal expansion has a problem in strength and price, and is attached to the outer periphery of the base metal 13. Preferably.

Fe-Ni- called Fernico (also called "Kovar") is a metal having a small coefficient of thermal expansion.
It is preferable to use a Co-based alloy, but the present invention is not limited to this.

Another embodiment using this Fernico will be described below.

FIG. 2 is a schematic view of a vitrified bond superabrasive grindstone according to this embodiment. The vitrified bond superabrasive grindstone 21 according to the present embodiment is provided with a Fernico layer 25 made of Fernico (Fe—Ni—Co alloy) on the outer periphery of the metallic base metal 13 by electron beam welding. 25 and a grindstone inner layer (containing Al ₂ O ₃ abrasive grains) 22B constituting the grindstone layer 22 are joined by a brazing layer 14 made of Ti-containing silver solder.

In this embodiment, a CB having a grain size of 80, a concentration of 200, and a thickness of 3 mm is used as the outer layer 22A of the whetstone layer 22.
In addition to forming the N grindstone layer, an Al ₂ O ₃ grindstone layer having a grain size of 120 and a thickness of 3 mm is formed as the grindstone inner layer 22B.
Therefore, in this embodiment, as compared with the grindstone shown in FIG.
Since the degree of concentration of the outer layer 22A of the grindstone is doubled and the coefficient of thermal expansion is low, and the thickness of the inner layer 22B of the grindstone is thin, the effect of stress relaxation is reduced, but the Fernico layer 25 is formed on the outer periphery of the base metal 23. By providing two grinding stone base layers, the thermal expansion coefficient of the Fernico layer 25 is small, so that peeling after cooling after brazing does not occur and the adhesive strength can be improved. The adhesive strength between the Fernico layer 25 and the grindstone layer 22 is 6 kg / mm ² , and the peripheral speed of the grindstone is about 2.5 times that of the conventional one.

In the present embodiment, the grindstone layer has a two-layer structure in which CBN super-abrasive grains are arranged in the grindstone outer layer and Al ₂ O ₃ abrasive grains are arranged in the grindstone inner layer in any of the embodiments. The invention is not limited to this, and may be, for example, a single layer or a mixed layer of superabrasive grains such as CBN or abrasive grains such as Al ₂ O ₃ .

[0021]

As described above in detail with the embodiments,
The vitrified bond superabrasive grindstone according to the present invention significantly improves the bonding strength of the base layer and the base metal by brazing, and can perform superhigh speed rotation with a significantly higher peripheral speed than the conventional one, As a result, the grinding efficiency can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a vitrified bond superabrasive grindstone according to this embodiment.

FIG. 2 is a schematic view of a vitrified bond superabrasive grindstone according to another embodiment.

FIG. 3 is a schematic view of a vitrified bond superabrasive grindstone according to a conventional technique.

[Explanation of symbols]

 11,21 Vitrified bond superabrasive grindstone 12,22 Grindstone layer 12A, 22A Grindstone outer layer 12B, 22B Grindstone inner layer 13 Base metal 14 Brazing layer 25 Fernico layer

Front page continuation (72) Inventor Hiromi Tonoto 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute (72) Inventor Tokuya Hamamoto 1 Uzumasa-cho, Ukyo-ku, Kyoto Prefecture Mitsubishi Heavy Industry Co., Ltd.Kyoto Seiki Works

Claims (3)

[Claims] 1. A vitrified bond superabrasive grindstone in which superabrasive grains composed of CBN or diamond are hardened by vitrified bond, and brazed between a grindstone layer containing the abrasive grains and a metallic base metal. A vitrified bond superabrasive whetstone that is characterized. 2. The vitrified bond superabrasive grindstone according to claim 1, wherein a metal having a low coefficient of thermal expansion is arranged on the outer periphery of the metallic base metal. 3. The vitrified bond superabrasive grindstone according to claim 2, wherein Fernico (Fe—Ni—Co alloy) is used as a metal having a low coefficient of thermal expansion.