JPH058177A - Centrifugal sintering method of metal bond grinding wheel - Google Patents

Abstract

PURPOSE:To obtain a sintering method of a metal bond grinding wheel with high grain holding power without raising the sintering temperature. CONSTITUTION:There is provided an aluminum alloy core 4 as a base metal at the center of a grinding wheel manufacturing metal mold 5. After grains 2 and spherical Ni (nickel) powder 3 as a binding material are filled up in the clearance between the metal mold 5 and the aluminum alloy core 4 and enclosed, the metal mold 5 is heated to melt the aluminum alloy 4 inside. The metal mold 5 is rotated, forming the metal bond grinding wheel by the centrifugal force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for firing a metal bond grindstone, and more particularly to a method for firing a metal bond grindstone by a centrifugal firing method.

[0002]

2. Description of the Related Art A metal bond grindstone is generally formed by a so-called powder metallurgy method in which a mold is filled with powder in which metal powder serving as a binder is mixed with abrasive grains and the mixture is sintered by applying heat and pressure. There is.

In this firing method, a Cu-Sn-based binder is often used as the abrasive grain binder. In particular, in order to extend the life of the product, a hard metal (Fe, Co, Ni, etc.) is added to improve the durability. Abrasion resistance is improved.

[0004]

However, the above Fe,
When using hard metals such as Co and Ni, it is necessary to raise the sintering temperature because these hard metals are difficult to sinter.
There is concern about the effect on the abrasive grains such as diamond.

Therefore, the problem to be solved by the present invention is to obtain a method for firing a metal bond grindstone having a high abrasive grain retention force without raising the sintering temperature.

[0006]

In the centrifugal firing method for a metal-bonded grindstone of the present invention, an aluminum alloy core as a base material is installed in the center of a die for manufacturing a grindstone, and an abrasive is provided in a gap between the die and the aluminum alloy core. It is characterized in that spherical Ni (nickel) powder as particles and a binder is filled and sealed, the mold is heated to melt the aluminum alloy inside, and the mold is rotated and molded by centrifugal force.

The spherical Ni powder reacts with the molten aluminum to cause a diffusion reaction from the contact portion to form a hard compound phase. At that time, a large amount of NiAl compound phase having a hardness of Hv 700 to 800 is generated in the outer peripheral portion of the spherical Ni powder, and
A large amount of NiAl ₃ compound phase having a hardness of Hv 800 to 1000 is generated in the gap between the abrasive grains and the spherical Ni powder. Therefore, the hard compound phase reliably holds the abrasive grains such as diamond. In particular, since spherical Ni powder is used, the permeability of molten aluminum is good, and the compound phase that holds the abrasive grains has a continuous network structure with high homogeneity.

Further, since the pure Ni portion, which is the central portion of the spherical Ni powder that does not react with the molten aluminum, is soft, it is scooped out by the cutting powder when the grindstone is used, and this becomes the chip pocket of the mesh structure for a long time. And good sharpness can be obtained.

The particle size of the Ni powder used here is preferably # 80 to # 150 in order to leave the pure Ni portion.
In addition, the content is preferably 30 to 70% by volume of the entire grindstone layer in order to obtain a predetermined binding force and control the degree of concentration of abrasive grains. Further, the diamond powder is preferably 5 to 25% by volume of the whole grindstone layer.

Since aluminum alloy is used as the melting temperature, it is not necessary to raise the melting temperature as compared with the case of using the conventional hard metal, and 600 to 7 which does not adversely affect the abrasive grains.
50 ° C is suitable. Further, the centrifugal force applied is 100 to 1000 G in order to sufficiently impregnate between the abrasive grains and the metal binder.
Is appropriate.

The progress of compounding can be controlled by the sintering temperature and centrifugal force. That is, the progress can be promoted by increasing the sintering temperature, and suppressed by decreasing the sintering temperature. Further, when the centrifugal force is increased, the impregnation speed is increased, and accordingly, the compounding speed can be increased.

[0012]

EXAMPLE FIG. 1 is a sectional view of a centrifugal baking machine 1 used in the centrifugal baking method of a metal bond grindstone, 2 is an abrasive grain (diamond grain), 3 is a spherical Ni powder, 4 is a base metal (aluminum alloy core). ) 5 is a mold or carbon type, and 6 is a heater.

In this embodiment, after an aluminum alloy to be a base metal is installed in the mold of the centrifugal baking machine 1 or the carbon mold 5,
Spherical Ni powder 3 having a particle size of # 100 is 40% by volume of the whole grindstone layer, diamond particles 2 is also 6.25% by volume, and liquid paraffin is dripped and mixed sufficiently in order to eliminate uneven mixing, and then the mold or The gap between the carbon mold 5 and the aluminum alloy core 4 was filled and sealed. Then, in an inert gas atmosphere, the aluminum alloy core was melted by heating to 650 ° C. or higher than the melting point of the aluminum alloy. Thereafter, a rotational force was applied and a centrifugal force of 350 G was used to impregnate molten aluminum into the gaps between the abrasive grains and the powder of the bonding material to manufacture a metal bond grindstone.

FIG. 2 is a partially enlarged sectional view of this grindstone.
2 is diamond abrasive grain, 3 is spherical Ni powder, 7 is spherical Ni
The NiAl compound phase formed on the outer peripheral portion of the powder 3 and the NiAl ₃ compound phase 8 formed in the gap between the abrasive grains 2 and the spherical Ni powder 3 are shown.

A grinding test was conducted under the following conditions using this metal bond grindstone. As a comparative example, the conventional Cu
A powder metallurgical method using a Sn-based binder was used.

The conditions for carrying out the grinding test are as follows.

Tester: Vertical axis rotary surface grinder Test wheel: 150D × 28L × 2.5W × 10N
(Segment cup wheel) Granularity 140, concentration 2
5 Work: Float plate glass wheel peripheral speed: 1200 m / min Depth of cut: 0.3 mm / min Total grinding amount: 1600 cc FIG. 3 shows the respective grinding ratios and power consumption values.

As is clear from the figure, the metal-bonded grindstone manufactured by the firing method of this example has an advantage in that the grinding ratio is improved by 40% and the power consumption is reduced by 13%. It was

In this embodiment, the centrifugal calcination machine shown in FIG. 1 is used, but it is of course possible to employ it in a so-called swing type centrifugal calcination machine having a rotary shaft outside the mold. Is.

[0020]

According to the present invention, the following effects can be obtained.

Spherical Ni powder added as a binder reacts with molten aluminum to form a NiAl compound phase or N around the abrasive grains.
Since the iAl ₃ compound phase is formed, the abrasive grains are securely retained.

Further, unlike the conventional hard metal, it is not necessary to raise the sintering temperature, so that the abrasive grains themselves are not adversely affected.

The pure Ni portion is cut off at the time of grinding, a large number of chip pockets are formed, and good sharpness is obtained.

It is lightweight because it uses an aluminum alloy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a centrifugal baking machine used for a centrifugal baking method of a metal bond grindstone.

FIG. 2 is a partially enlarged cross-sectional view of a metal bond grindstone according to the manufacturing method of the present invention.

FIG. 3 is a diagram showing a grinding ratio and a power consumption value.

[Explanation of symbols]

1 Centrifugal Firing Machine 2 Abrasive Grains (Diamond Grains) 3 Spherical Ni Powder 4 Base Metal (Aluminum Alloy Core) 5 Mold (Carbon Type) 6 Heater 7 NiAl Compound Phase 8 NiAl ₃ Compound Phase

Claims (3)

[Claims] 1. An aluminum alloy core as a base material is installed in the center of a die for manufacturing a grindstone, and an abrasive grain and a binder are filled in a gap between the die and the aluminum alloy core, and the die is sealed. In a centrifugal firing method of a metal bond grindstone that is heated to melt an aluminum alloy inside, and rotates the mold to form by centrifugal force, spherical Ni powder is used as the binding material of the metal bond grindstone. Centrifugal firing method. 2. The centrifugal firing method for a metal bond grindstone according to claim 1, wherein the spherical Ni powder has a particle size of # 80 to # 150. 3. The content of spherical Ni powder is 3 in the entire grindstone layer.
The centrifugal firing method for a metal bond grindstone according to claim 1 or 2, wherein the content is 0 to 70% by volume.