JP2931128B2 - Centrifugal firing method of metal bond whetstone - Google Patents

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-bonded grinding wheel, and more particularly to a method for firing a metal-bonded grinding wheel 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 obtained by mixing a metal powder serving as a binder and abrasive grains, and sintering is performed by applying heat and pressure. I have.

[0003] In this firing method, a Cu-Sn-based binder is often used as a binder for abrasive grains. Particularly, in order to extend the life of a product, a hard metal (Fe, Co, Ni, or the like) is added to withstand resistance. Abrasion 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.

Accordingly, an object of the present invention is to provide a method for firing a metal-bonded grindstone having a high abrasive grain holding force without increasing the sintering temperature.

[0006]

According to the centrifugal firing method of a metal bond whetstone of the present invention, an aluminum alloy core serving as a base material is installed at the center of a die for manufacturing a whetstone, and a gap is provided between the die and the aluminum alloy core. After filling and sealing spherical Ni (nickel) powder as particles and a binder, the mold is heated to melt the aluminum alloy therein, and the mold is rotated to be formed by centrifugal force.

[0007] 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 this time, many NiAl compound phases having a hardness of Hv 700 to 800 are generated on the outer peripheral portion of the spherical Ni powder,
Many NiAl ₃ compound phases having a hardness of 800 to 1000 Hv are generated in the gaps between the abrasive grains and the spherical Ni powder. For this reason, the abrasive grains such as diamond are reliably held by the hard compound phase. In particular, since a spherical Ni powder is used, the permeability of the molten aluminum is good, and the compound phase holding the abrasive grains has a continuous network structure and high homogeneity.

In addition, 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 cut off by cuttings when using a grindstone, and this becomes a chip pocket having a network structure, which is used for a long time. Good sharpness is obtained.

The particle size of the Ni powder used here is preferably from 80 to 150 in order to leave a 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 bonding force and control the degree of concentration of abrasive grains. Further, the diamond powder is preferably from 5 to 25% by volume of the whole grindstone layer.

[0010] Since the aluminum alloy is used as the melting temperature, it is not necessary to raise the temperature as compared with the case where a conventional hard metal is used.
50 ° C. is suitable. The applied centrifugal force is 100 to 1000 G 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 the centrifugal force. That is, when the sintering temperature is increased, the progress can be promoted, and when it is decreased, the sintering temperature can be suppressed. In addition, when the centrifugal force is increased, the impregnation speed increases, and accordingly, the compounding speed can be increased.

[0012]

FIG. 1 is a cross-sectional view of a centrifugal firing machine 1 used for a centrifugal firing method of a metal bond whetstone, wherein 2 denotes abrasive grains (diamond grains), 3 denotes spherical Ni powder, and 4 denotes base metal (aluminum alloy core). ), 5 indicates a mold or a carbon mold, and 6 indicates a heater.

In this embodiment, an aluminum alloy serving as a base metal is installed in a mold or a carbon mold 5 of the centrifugal sintering machine 1.
The spherical Ni powder 3 having a particle size of about 100 is 40% by volume of the whole grindstone layer, the diamond particles 2 are also 6.25% by volume, and liquid paraffin is dropped and mixed sufficiently to eliminate uneven mixing. The gap between the carbon mold 5 and the aluminum alloy core 4 was filled and sealed. Then, it was heated to 650 ° C. or higher than the melting point of the aluminum alloy in an inert gas atmosphere to melt the aluminum alloy core. Thereafter, a rotating force was applied and molten aluminum was impregnated into the gaps between the powder of the abrasive grains and the binder by the centrifugal force of 350 G to produce a metal-bonded grindstone.

FIG. 2 is a partially enlarged sectional view of the grinding wheel.
2 is diamond abrasive, 3 is spherical Ni powder, 7 is spherical Ni
Reference numeral 8 denotes a NiAl compound phase formed on the outer periphery of the powder 3, and 8 denotes a NiAl ₃ compound phase formed in the gap between the abrasive grains 2 and the spherical Ni powder 3.

Using this metal-bonded grindstone, a grinding test was performed under the following conditions. As a comparative example, the conventional Cu
A powder metallurgy method using a Sn-based binder as a binder was used.

The conditions for the grinding test are as follows.

Test machine: Vertical axis rotary surface grinder Test wheel: 150D × 28L × 2.5W × 10N
(Segment cup wheel) Grain size 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 apparent from the figure, the metal-bonded grindstone manufactured by the firing method of this embodiment achieves a 40% improvement in the grinding ratio and a 13% reduction in the power consumption value. Was.

In this embodiment, the centrifugal baking machine shown in FIG. 1 has been described. However, it is of course possible to employ a so-called swing type centrifugal baking machine having a rotating shaft outside the mold. It is.

[0020]

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

The spherical Ni powder added as a binder reacts with the 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 held.

Further, since it is not necessary to increase the sintering temperature unlike the conventional hard metal, there is no adverse effect on the abrasive grains.

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

The use of an aluminum alloy results in a light weight.

[Brief description of the drawings]

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

FIG. 2 is a partially enlarged cross-sectional view of a metal-bonded grindstone manufactured by the method of the present invention.

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Centrifugal baking 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) B24D 3/06 B24D 3/00 340 B24D 3/02 310 C04B 37/00

Claims (3)

(57) [Claims] 1. An aluminum alloy core serving as a base material is provided at the center of a mold for manufacturing a grindstone, and a gap between the mold and the aluminum alloy core is filled with abrasive grains and a binder, and the mold is sealed. In the centrifugal firing method of a metal bond grindstone, which is heated to melt the internal aluminum alloy, and the mold is rotated and formed by centrifugal force, a spherical Ni powder is used as the binder. Centrifugal firing method. 2. The method of claim 1, wherein the spherical Ni powder has a particle size of $ 80 to $ 150. 3. The content of the spherical Ni powder is 3% of the whole grindstone layer.
The method for centrifugally firing a metal-bonded grindstone according to claim 1 or 2, wherein the amount is 0 to 70% by volume.