JPH0615575A - Grinding wheel - Google Patents

Abstract

PURPOSE:To provide a grinding wheel that is less in elongation of a disk-like base at the time of rotation and able to perform a job for highly accurate machining in addition to being hard to cause any crack in the grinding wheel part. CONSTITUTION:This grinding wheel 1 is featured in that a disk-like base 2 consists of a material of more than 10000kgf/mm<2> in specific modulus, in a structure made up of solidly forming a grinding wheel part 3 on the circumferential surface of the disk-like base 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding wheel.

[0002]

2. Description of the Related Art Conventionally, as a grinding wheel, there is a grinding wheel in which a wheel portion is integrally formed on the outer peripheral surface of a disk-shaped base.
The grindstone portion of the grinding grindstone is integrally formed on the base in the following manner.

That is, after a mixture of a binder and abrasive grains is placed along the outer periphery of a disk-shaped base made of steel or aluminum alloy in a mold and pressure-molded,
It is sintered by heating and firing, and the abrasive grains are fixed to the outer peripheral surface of the base with a binder.

The inventors of the present invention have studied the use of this grinding wheel to grind a glass lens, a glass mirror, a ceramic mirror, etc. at an extremely high speed. I found something.

Sufficient processing accuracy cannot be obtained. When grinding, attach a grinding wheel to the rotary shaft of the machine tool by using the shaft hole provided in the center of the base, and rotate the grinding wheel at an extremely high rotational speed of, for example, 80,000 times per minute. Be careful
The grinding wheel is moved along the surface of the material in contact with the lens material.At this time, the disk-shaped base is extended in the radial direction by the centrifugal force generated by the ultra-high speed rotation, and the external dimensions of the grinding wheel. Changes, and this dimensional change appears as a processing error, resulting in lower processing accuracy.

Moreover, cracks are likely to occur near the bonding surface of the grindstone portion. As mentioned above, at the time of ultra-high speed rotation, the disk-shaped base tends to extend greatly in the radial direction,
The grindstone has higher rigidity and does not stretch much. As described above, since there is a difference in elongation property between the grindstone portion and the base, the grindstone portion is strongly pushed outward by the disk-shaped base, so that the grindstone portion is cracked.

[0007]

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a grinding wheel in which the disc-shaped base is less stretched even during ultra-high speed rotation.

[0008]

In order to solve the above-mentioned problems, the present invention provides a grinding wheel in which a grindstone portion is integrally formed on the outer peripheral surface of a disk-shaped base, and the base has a specific elastic modulus of 10000 kgf. The feature is that it is made of a material of / mm ² or more.

The specific elastic modulus in the present invention is obtained according to the following equation (1). [Young's modulus (kgf / mm ² ) / specific gravity] = [specific elastic modulus (k
gf / mm ² )] (1) In the grinding wheel of the present invention, the disk-shaped base has a specific elastic modulus of 1
It is sufficient if it is made of a material having a specific gravity of 0000 kgf / mm ² or more, and it is more suitable if it is a material having a low specific gravity of 2.5 or less. Material with smaller specific gravity
This is because, as can be seen from the above formula, it is advantageous in having a high specific elastic modulus characteristic and, moreover, the grindstone itself can be made lighter. Specific examples of the suitable base material include beryllium and a composite material in which beryllium is combined with another suitable metal, but other materials may be used.

Beryllium has a Young's modulus of 28,000 kg.
f / mm ² , specific gravity: 1.84, specific elastic modulus: 152
The material is 00 kgf / mm ² . By the way, the steel conventionally used as the base material has a Young's modulus of 21,000 kg.
Although it has a high f / mm ^2, it has a high specific gravity of 7.9, and thus has a very low specific elastic modulus of 2620 kgf / mm ² . Since the Young's modulus of aluminum alloy is as low as 7200 kgf / mm ² , even if the specific gravity is as low as 2.8, the specific elastic modulus is 2570 kgf / mm 2.
^As low as ² .

The grindstone portion of the grinding grindstone of the present invention can be integrally formed on a disk-shaped base in the following manner as in the conventional case. That is, in a mold, a mixture of a binder and abrasive grains is arranged along the outer periphery of a disk-shaped base made of beryllium, and the mixture is molded. It is fixed to the outer peripheral surface of the base. Therefore, the material of the disk-shaped base is usually capable of withstanding the heating temperature applied during firing. It goes without saying that the base made of beryllium has the necessary heat resistance.

Abrasive grains used for the grindstone portion usually have a grain size of 1
˜50 μm, specifically,
CBN grains (cubic boron nitride grains), diamond grains, WA
Examples thereof include grains (alumina grains) and GC grains (Green Caborundum: silicon carbide grains). On the other hand, examples of the binder mixed with the abrasive grains include vitrified, resinoid (such as polyimide and epoxy), and soft metal powder.

The grinding wheel according to the present invention can be used for grinding a glass lens, a glass mirror, a ceramic mirror, etc., for example. Ultra high speed (diameter 6) where the peripheral speed of the grinding wheel reaches 5000 to 20000 m / min.
(25,000 to 100,000 revolutions per minute for 0 mm grinding wheel)
It is conceivable to perform the processing of. Of course, it goes without saying that the grinding wheel of the present invention can be used for polishing / grinding processing other than lens and mirror processing.

[0014]

In the grinding wheel according to the present invention, the disk-shaped base is made of a material having a specific elastic modulus of 10000 kgf / mm ² or more, and it is difficult for the disk to be stretched by mechanical force. Even if it is rotated at ultra-high speed, the elongation of the base will be smaller than before. As a result, the dimensional change of the grinding wheel becomes smaller, so that the processing accuracy is improved, and the force applied to the grinding wheel portion is also reduced, so that cracks are less likely to occur.

For example, when a base having an outer diameter of 60 mm, an inner diameter of 40 mm and a thickness of 2 mm is rotated at 80,000 revolutions per minute, the elongation of each material is "steel plate ... 396 μm", "aluminum alloy plate ... 404 μm", "titanium plate". ..393 μm ”
On the other hand, in the beryllium plate of the present invention, “70
It is limited to the growth of μm.

In addition, when the specific gravity of the material of the base is 2.5 or less, the grindstone itself becomes light, so that the energy required for rotation is reduced and the bearing is not overloaded and unbalanced. Is less likely to occur and the rotation blur is suppressed, so there is no processing unevenness, and it is possible to save the trouble of correction processing.

When the disk-shaped base is made of beryllium, the base has a high specific elastic modulus and a low specific gravity, and also has good plating workability. When using a metal bond (bond of copper-based, nickel-based, iron-based, etc.) as the bonding agent, in order to enhance the bonding force between the grindstone and the base, the base is pre-plated before forming the grindstone ( For example, nickel plating) may be applied, but a beryllium base is easy to plate.

[0018]

Embodiments of the present invention will be described below. Of course,
The present invention is not limited to the embodiments described below.

Example 1 FIG. 1 shows the appearance of a grinding wheel according to an example.

The grinding wheel 1 of the embodiment has a structure in which a wheel part 3 is provided along the outer peripheral surface of a disk-shaped base 2.

The disk-shaped base 2 is made of beryllium, and the grindstone portion 3 is made of CBN grains as abrasive grains and vitrified as a binder.

A shaft hole 4 for mounting on a rotary shaft of a machine tool is formed in the center of a disk-shaped base 2.

Example 2 In the grinding wheel of Example 2, the binder was a bronze-based metal bond, and the whetstone portion 3 was provided after nickel-plating the base 2 made of beryllium in advance. Example 1
It has the same structure as.

Example 3 The grinding wheel of Example 3 has the same structure as that of Example 1 except that the abrasive grains are diamond grains.

Example 4 In the grinding wheel of Example 4, the binder was a bronze-based metal bond, and the surface of the base 2 made of beryllium was nickel-plated in advance, and then the wheel portion 3 was provided. Example 3
It has the same structure as.

Example 5 The grinding wheel of Example 5 is the same as Example 1 except that the abrasive grains are WA.
It has the same structure as.

Example 6 In the grinding wheel of Example 6, the binder was bronze-based metal bond, and the surface of the base 2 made of beryllium was preliminarily plated with nickel and then the wheel portion 3 was provided. Example 5
It has the same structure as.

When the grinding wheels of Examples 1 to 6 were used to process lenses used in video (movie) cameras, surveillance cameras, etc., they could be processed with required accuracy.
During lens processing, as shown in FIG. 2, a rotary shaft of a machine tool (not shown) is ground by using a shaft hole 4 provided in the center of the (disk) of the disk-shaped base 2. Attach grindstone 1
Rotate the grinding wheel 1 at a rotational speed of 80,000 times per minute,
Grinding stone 1 along the surface in the state of hitting the lens material W
To move.

[0029]

EFFECT OF THE INVENTION In the grinding wheel according to the present invention, the base is made of a material having a specific elastic modulus of 10,000 kgf / mm ² or more, and the base is hard to stretch against mechanical force. Since the elongation of the base when rotated at high speed is smaller than before, the dimensional change of the grinding wheel is small and the processing accuracy is improved, and the force applied to the grinding wheel is reduced and cracks are less likely to occur. Is very useful.

When the material of the disk-shaped base of the grinding wheel has a specific gravity of 2.5 or less, the wheel itself becomes light, so that the energy required for rotation is small, and there is no processing unevenness and correction processing. There is an added benefit of saving time and effort.

The disk-shaped base made of beryllium has a significantly small elongation during rotation of the base, and in addition to the remarkable effect of reducing the weight of the grindstone itself, the bonding between the grindstone and the base. There is also an advantage that it is excellent in plating workability for increasing power.

[Brief description of drawings]

FIG. 1 is an external perspective view of a grinding wheel according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of lens processing by a grinding wheel according to an embodiment of the present invention.

[Explanation of symbols]

 1 Grinding wheel 2 Disc-shaped base 3 Wheel section 4 Shaft hole

Claims (3)

[Claims] 1. A grinding wheel in which a whetstone portion is integrally formed on the outer peripheral surface of a disk-shaped base, wherein the base has a specific elastic modulus of 1
A grinding wheel made of a material of 0000 kgf / mm ² or more. 2. The grinding wheel according to claim 1, wherein the material of the base has a specific gravity of 2.5 or less. 3. The material of the base is beryllium.
Grinding wheel described.