JPH06262527A - Grinding wheel - Google Patents

Abstract

PURPOSE:To increase working efficiency by providing abrasive grains with diamond and cubic system boron nitride, reducing the rotation of dressing and tooling, and also reducing power required for grinding, in a grinding wheel with an abrasive grain layer in which abrasive grains are dispersed and fixed in a bonding phase. CONSTITUTION:In a grinding wheel, an abrasive grain layer 2 is formed on an abrasive grain layer forming surface 1A of a base metal 1, the abrasion grain layer 2 is made by dispersing and fixing abrasive grains 4 in a bonding phase 3, and diamond and cubic system boron nitride(CBN) are used as the abrasive grains 4. When grinding is made using a grinding wheel of such structure, the abrasive grains 4 become difficult to wear during grinding due to presence of diamond in the abrasive grains 4. Accordingly, the service life of the grinding wheel is prolonged and cost is reduced. Also, because grinding performance is increased by occasional collapse of CBN in the abrasive grains 4, grinding speed is increased and also power is reduced. In addition, because burrs formed at the rear of the surfaces to be cut become small in size, post- treatment after grinding is also facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grindstone having an abrasive grain layer and used for various grinding processes, and more particularly to improvement of a grindstone for improving grinding performance and extending the life of the grindstone. .

[0002]

2. Description of the Related Art As one type of grindstone used for various grinding processes, there is one having an abrasive grain layer composed of a binder phase composed of a binder and abrasive grains dispersed and fixed in the binder phase.
Generally, a resin bond, a vitrified bond, a metal bond, or the like is used as the binder phase, and either diamond or cubic boron nitride (hereinafter abbreviated as CBN) is often used as the abrasive grains. here,
Diamond is characterized by high hardness and toughness, and CBN is characterized by high friability.

Therefore, when performing precision grinding of an iron-based sintered component having excellent wear resistance, such as a rotor of a trochoid pump, a grindstone using diamond as abrasive grains (hereinafter,
It is called a diamond grindstone. If the grinding is performed with (1), since the abrasive grains are tough, the life of the grindstone is long, which is advantageous in terms of cost.
Moreover, when it is used for double-sided grinding, there is an advantage that the parallelism of the work surfaces formed above and below the work becomes high.

On the other hand, when grinding is performed with a grindstone using CBN as abrasive grains (hereinafter referred to as CBN grindstone), the abrasive grains are appropriately crushed during grinding, and as a result, sharp abrasive grains are always provided for grinding. Therefore, the grinding performance is improved. Therefore, the grinding speed can be increased and the power required for grinding can be reduced. Also,
Generally, when grinding is carried out while making surface contact between the abrasive grain layer and the work material, burrs are formed at the rear end of the work surface due to grinding,
Grinding with a CBN grindstone has an advantage that burrs are reduced due to high grinding performance.

[0005]

By the way, in a diamond grindstone, the abrasive grains are tough, but the sharpness of the abrasive grains tends to be lost due to the abrasion accompanying the grinding, and the grinding performance tends to deteriorate. As a result, large burrs are formed at the rear end of the work surface as compared with grinding with a CBN grindstone, and these burrs are difficult to remove even by post-treatment such as barrel polishing.
There is a problem that the post-processing becomes troublesome. On the other hand, CB
When the N grindstone is used for grinding, the abrasive grains are likely to be crushed, so that the wear of the abrasive grain surface becomes faster. As a result, there is a problem that the life of the grindstone is shortened and dressing and tooling must be frequently performed.

[0006]

The present invention has been made in view of the above circumstances, and is a grindstone having an abrasive grain layer in which abrasive grains are dispersed and fixed in a bonding phase, wherein the abrasive grains are diamond. And CBN.

[0007]

The grinding stone of the present invention is hard to wear because the abrasive grains contain diamond, and has high grinding performance because the abrasive grains have CBN.

[0008]

Embodiments of the present invention will now be described in more detail with reference to the drawings. FIG. 1 is an enlarged view of a cross section of a grindstone showing an embodiment of the grindstone according to the present invention. Reference numeral 1 in the figure
Is a base metal, and the shape of the base metal 1 is not limited to a cup type,
A base metal of any shape conventionally used such as a wheel type or a general type may be used.

An abrasive grain layer 2 is formed on the abrasive grain layer forming surface 1A of the base metal 1. This abrasive grain layer 2 includes abrasive grains 4 in the bond phase 3.
In this embodiment, a resin bond is used for the binder phase 3 and diamond and CBN are used as the abrasive grains 4. Here, abrasive grain 4
It is desirable that the degree of concentration is 30 to 70. this is,
This is because when the concentration is less than 30, the grinding ratio is lowered and the grinding performance is deteriorated, whereas when the concentration is more than 70, the abrasive grain holding force becomes insufficient.

The grain size of the abrasive grains 4 is diamond: C
It is desirable that BN = 1: 1.3 to 1.5. This is because when the grain size of diamond is less than 1.3 times CBN, diamond acts as a filler and does not act on grinding, while when the grain size of diamond exceeds 1.5 times CBN, the effect of diamond is This is because the effect of mixing the abrasive grains is small and the effect is small.

Further, the mixing ratio of the abrasive grains 4 is diamond:
It is desirable to set CBN = 70: 30 to 40:60. This is because when the diamond mixing ratio is less than 40%, the abrasion of the grindstone becomes faster and the life of the grindstone is shortened.
This is because if the mixing ratio of diamond exceeds 70%, large burrs are formed at the peripheral edge of the work surface, and the post-treatment after grinding becomes troublesome.

When grinding is performed with the grindstone having the above structure, the presence of diamond in the abrasive grains 4 makes it difficult for the abrasive grains 4 to wear during the grinding. Therefore, the life of the grindstone is long,
It is cost effective. Further, the CBN in the abrasive grains 4 is appropriately collapsed to improve the grinding performance, so that the grinding speed is fast and the power is small. Moreover, since the burr formed at the rear end of the surface to be cut becomes small as in the case of grinding with a CBN grindstone, post-processing after grinding becomes easy.

A vitrified bond may be used as the binder phase 3, but in this case, the concentration of the abrasive grains 4 is 4%.
It is desirable to set 0 to 100. This is because when the vitrified bond is used for the binder phase 3, the degree of concentration is 40.
If it is less than 100%, the grinding ratio is lowered and the grinding performance is lowered. On the other hand, if the degree of concentration exceeds 100, the abrasive grain holding force becomes insufficient.

[0014]

[Experimental Examples] Experimental effects will be described below with reference to experimental examples. Experimental Example 1 Grinding was performed using different grindstones, and the current value (main axis current value) consumed by the machine spindle during grinding
The change with grinding wheel fall was measured. Grinding stones used in the experiment are the following four kinds. (Comparative Example 1) CBN Abrasive Grains (Comparative Example 2) Diamond Abrasive Grains (Comparative Example 3) A mixing ratio CB of the CBN abrasive grains used in Comparative Example 1 and the diamond abrasive grains used in Comparative Example 2 above.
N: Diamond = 2: 1 mixed (Invention Example 1) The mixing ratio CB of the CBN abrasive grains used in Comparative Example 1 and the diamond abrasive grains used in Comparative Example 2 above.
N: diamond = 1: 1 mixed The grindstone diameters were all 200 (D) × 5 (W) × 3 (X), and the grain size was unified to # 170. Further, the same type of resin bond was used for the binder phase.

Further, all the grinding conditions are unified to the following conditions. Grinding wheel speed: 2400r.pm Cutting speed: 0.05mm / min Work material: Sintered parts

FIG. 2 shows the change in the spindle current value due to the change in the drop amount due to grinding. As can be seen from FIG. 2, the spindle current value was always the lowest when the wheel of Invention Example 1 was used. This indicates that the grindstone shown in Invention Example 1 has the highest cutting ability.

In FIG. 2, the spindle current value in Comparative Example 1 (when the CBN grindstone is used) exceeds the spindle current value in Comparative Example 2 (when the diamond grindstone is used), which is CBN. In the grinding area where the abrasive grains are crushed, the spindle current value does not rise because of the self-generated effect, but C
This is because autogenous action does not occur in the grinding area accompanied by abrasion of the BN abrasive grains, and as a result, the spindle current value increases.

Experimental Example 2 Grinding wheels having different grinding types were used, grinding was performed at different cutting speeds, and changes in the current value consumed by the machine spindle during grinding were measured. The grinding types of the grindstones used in the experiment are the following three types. (Comparative example 4) CBN abrasive grains (Comparative example 5) Diamond abrasive grains (Invention example 2) A mixture of diamond abrasive grains with a mixing ratio of CBN: diamond = 1: 1. (W) × 3 (X), and the abrasive grain size was unified to # 170. Further, the same type of resin bond was used for the binder phase.

Further, all the grinding conditions are unified to the following conditions. Grindstone rotation speed: 2380r.pm Cutting speed: 0.025, 0.05, 0.1 (mm / min) 3 steps Work material: Iron-based sintered parts

FIG. 3 shows the change in the spindle current value with the change in the cutting speed. As can be seen from Fig. 3, when the cutting speed is at least 0.05 mm / min, the spindle current value is
The worst was the case where the grinding stone of Inventive Example 2 was used. This indicates that under the above conditions, the cutting ability of the grindstone shown in Inventive Example 2 is the highest. In Invention Example 2, the grain size of the abrasive grains is diamond: CBN = 1: 1, but the grain size is diamond: CBN = 1: 1.3.
When it is set to 1.5, the spindle current value can be made lower than that of the comparative example even if the cutting speed is 0.05 mm / min or more.

[0021]

As described above, by using the grindstone of the present invention, a grindstone having a long life and high grinding performance can be obtained. As a result, the frequency of dressing and tooling is reduced, and the power required for grinding is reduced, so that the work efficiency is improved.

[Brief description of drawings]

FIG. 1 is an enlarged view of a cross section of a grindstone showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an experimental example according to the present invention and is a diagram showing a relationship between a current value of a machine spindle and a change in a grindstone fall amount due to grinding.

FIG. 3 is a diagram showing an experimental example according to the present invention and is a diagram showing a relationship between a current value of a machine spindle and a change in cutting speed during grinding.

[Explanation of symbols]

 1 Metal 1A Abrasive grain layer forming surface 2 Abrasive grain layer 3 Bonding phase 4 Grinding stone

Claims (3)

[Claims] 1. A grindstone having an abrasive grain layer in which abrasive grains are dispersed and fixed in a binder phase, wherein the abrasive grains contain diamond and cubic boron nitride. 2. A resin bond is used as the binder phase, the concentration of the abrasive grains is 30 to 70, and the grain size of the abrasive grains is diamond: cubic boron nitride = 1: 1.3. .About.1.5, and the mixing ratio of the abrasive grains is diamond: cubic boron nitride = 70: 30.
The grindstone according to claim 1, wherein the grindstone is set to 40:60. 3. A vitrified bond is used as the binder phase, the concentration of the abrasive grains is 40 to 100, and the grain size of the abrasive grains is diamond: cubic boron nitride = 1: 1.3. .About.1.5, and the mixing ratio of the abrasive grains is diamond: cubic boron nitride = 7.
The grindstone according to claim 1, which is set to 0:30 to 40:60.