JP2006088243A - Abrasive grain and grindstone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide abrasive grain which is not only excellent in rigidity, wear resistance, and cleaving performance but also firmly fixed to a bonding agent, and to provide a grindstone using the abrasive grain, which is proof against separation of the abrasive grain from the bonding agent, and suitable for highly efficient grinding. <P>SOLUTION: The abrasive grain 10 has a smooth surface 11 which has a surface roughness of Ra 0.01 to 0.05 μm and makes up at least 30% of the entire surface area, and a rough surface 12 which has a surface roughness of Ra 0.06 to 0.20 μm and makes up at least 30% of the entire surface area. The grindstone is formed of the abrasive grain 10 and the binding agent. The abrasive grain 10 is formed of CBN (cubic boron nitride), and has the smooth surface 11 which has a surface roughness of Ra 0.01 to 0.05 μm and makes up at least 30% of the entire surface area, and the rough surface 12 which has a surface roughness of Ra 0.06 to 0.20 μm and makes up at least 30% of the entire surface area. The binding agent is formed of a vitrified bond. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to abrasive grains and a grindstone.

  In a grinding machine such as a cylindrical grinding machine, a grinding wheel is used. Here, the grinding wheel is formed in a disk shape and the outer peripheral surface is constituted by a grindstone. The outer peripheral surface of the workpiece is mounted on the grinding wheel base of the grinder and is driven to rotate by the grindstone on the outer peripheral surface. The surface to be ground is subjected to grinding. The grindstone of the grinding wheel is composed of various abrasive grains and binders, but representatively, abrasive grains formed of CBN (cubic boron nitride) (hereinafter referred to as “CBN abrasive grains”). Can be exemplified by those formed and fired using a vitrified bond as a binder. Here, the CBN abrasive grains are those obtained by crystallizing boron nitride in a cubic form, and are excellent in rigidity and wear resistance. Vitrified bond is a binder suitable for high-efficiency grinding with excellent heat resistance and increased grinding feed rate.

  The above background art is a general matter, and the applicant of the present application does not particularly know a document in which a description specifying the background art is made at the time of filing.

  By the way, most of the conventional CBN abrasive grains are composed of a (100) plane indicated by the Miller index used for specifying the plane of the crystal structure. Since the (100) plane is a cleaved surface of the CBN crystal, the CBN abrasive grains are hard to be cleaved by themselves and are highly rigid abrasive grains. In addition, when breakage occurs, the new (100) surface, which is a cleavage plane, is cracked so as to be exposed, so that a cutting edge with a good sharpness can be regenerated by truing. In addition, the characteristic which is largely broken when breakage occurs is referred to as “high cleaving property”, and the conventional CBN abrasive grains are abrasive grains having excellent cleaving characteristics.

  However, since the (100) plane of the CBN crystal has poor wettability of the binder and the binding force with the binder is weak, the conventional CBN abrasive grains are likely to fall off from the binder when used as a grindstone. was there. In particular, when high-efficiency grinding with a high grinding feed rate is performed, a high load is applied to the abrasive grains, and thus the problem that the abrasive grains easily fall off has occurred remarkably.

  This invention is made | formed in view of the said actual condition, and it makes it a subject to provide the abrasive grain which not only is excellent in rigidity, abrasion resistance, and cleaving property, but can be firmly fixed to a binder. It is another object of the present invention to provide a grindstone that uses this abrasive grain and is suitable for high-efficiency grinding because it is difficult for the abrasive grain to fall off the binder.

The main means taken by the present invention to solve the above problems are as follows:
“A smooth surface with a surface roughness of Ra 0.01 to 0.05 μm occupies at least 30% of the entire surface area,
Abrasive grain characterized in that a rough surface with a surface roughness of Ra 0.06-0.20 μm occupies at least 30% of the entire surface area ”
It is.

  A smooth surface having a surface roughness Ra of 0.01 to 0.05 μm is a surface necessary for ensuring rigidity, abrasion resistance, and cleavage properties as abrasive grains. Therefore, the occupied area of the smooth surface is set to at least 30% of the entire surface area. Thereby, the favorable rigidity, abrasion resistance, and cleavage property as an abrasive grain can be obtained.

  On the other hand, a rough surface having a surface roughness Ra of 0.06 to 0.20 μm is rougher than the above-described smooth surface, and is a surface with high wettability of the binder. Therefore, the occupied area of the rough surface is set to at least 30% of the entire surface area. Thereby, it can be set as the abrasive grain which can be firmly fixed to a binder.

  In order to form a smooth surface and a rough surface as the surface of the abrasive grains, when the abrasive grains are formed by crystallization of various molecules, the smooth surface and the rough surface as described above are used in the crystallization of the molecules. The molecules may be crystallized so that each has a surface exposed. Not limited to this, a part of the smooth surface is formed by various processing such as blasting with diamond powder, etching processing with chemicals, laser processing, plasma processing, etc. on abrasive grains whose entire surface is smooth. A rough surface may be formed by roughening. On the contrary, a smooth surface may be formed by smoothing a part of the rough surface by the above-described various processes on the abrasive grains whose entire surface is a rough surface.

In addition, the main means taken by the present invention to solve the above problems are as follows:
“Abrasive grains are formed of CBN (cubic boron nitride), a smooth surface with a surface roughness of Ra 0.01 to 0.05 μm occupies at least 30% of the entire surface area, and a surface roughness of Ra 0.06 to 020 μm. A rough surface is an abrasive occupying at least 30% of the entire surface area,
A grinding wheel characterized in that the binder is a vitrified bond "
It is.

  As described above, the abrasive grains are not only excellent in rigidity, abrasion resistance and cleaving properties, but also are abrasive grains that can be firmly fixed to the binder, and as abrasive grains, CBN abrasive grains are used. By using vitrified bond as a binder, a grindstone suitable for high-efficiency grinding can be obtained.

In addition, the main means taken by the present invention to solve the above problems are as follows:
“CBN (cubic boron nitride)
The (100) plane indicated by the Miller index occupies at least 30% of the entire surface area,
Abrasive grains characterized in that the (111) plane represented by the Miller index occupies at least 30% of the entire surface area "
It is.

  The (100) surface in the CBN abrasive grains is a surface necessary for ensuring the rigidity, abrasion resistance and cleavage properties as the abrasive grains. Therefore, the occupied area of the (100) plane is set to at least 30% of the entire surface area. Thereby, the favorable rigidity, abrasion resistance, and cleavage property as an abrasive grain can be obtained.

  On the other hand, the (111) plane in the CBN abrasive grains is a plane with high wettability of the binder, although it is inferior in rigidity, wear resistance and cleaving property as compared with the above (100) plane. Therefore, the occupied area of the (111) plane is set to at least 30% of the entire surface area. Thereby, it can be set as the abrasive grain which can be firmly fixed to a binder.

  In order to expose the (100) plane and the (111) plane as the surface of the abrasive grains, when the CBN crystal is crystallized, the (100) plane and the (111) plane are each exposed. Good.

In addition, the main means taken by the present invention to solve the above problems are as follows:
“Abrasive grains are made of CBN (cubic boron nitride), the (100) plane indicated by the Miller index occupies at least 30% of the total surface area, and the (111) plane indicated by the Miller index accounts for at least 30% of the total surface area. Occupying abrasive grains,
A grinding wheel characterized in that the binder is a vitrified bond "
It is.

  As described above, CBN abrasive grains that are not only excellent in rigidity, wear resistance, and cleavage properties but also can be firmly fixed to the binder are used as the abrasive grains, and vitrified bond is used as the binder. Thus, a grindstone suitable for high-efficiency grinding can be obtained.

  As described above, according to the present invention, it is possible to provide an abrasive that not only has excellent rigidity, wear resistance, and cleavage properties, but can be firmly fixed to a binder. Moreover, it is a grindstone using this abrasive grain, Comprising: Abrasive grains cannot fall easily from a binder and can provide a grindstone suitable for high-efficiency grinding.

  Next, an example of an embodiment of abrasive grains and a grindstone according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the abrasive grains 10 are composed of CBN crystals. Here, the surface of the abrasive grains 10 is damaged such as (100) plane 11, (111) plane 12, and (110) plane and chippings indicated by the Miller index used to specify the plane of the crystal structure. The other surface 13 is formed. Here, the (100) plane 11 occupies at least 30% of the entire surface area, and the (111) plane 12 occupies at least 30% of the entire surface area. The (100) surface 11 is a smooth surface with a surface roughness of Ra 0.01 to 0.05 μm, more specifically Ra 0.02 to 0.40 μm, and the (111) surface 12 is a surface The roughness is Ra 0.06 to 0.20 μm, more specifically, Ra 0.10 to 0.15 μm.

  The (100) surface 11 of the CBN crystal which is a smooth surface is a surface which can obtain excellent rigidity, wear resistance and cleavage. And in this abrasive grain 10, since at least 30% of the whole surface area is comprised by the (100) surface 11 which is a smooth surface, favorable rigidity, abrasion resistance, and cleavage property as an abrasive grain 10 are ensured. Is done.

  On the other hand, in the CBN crystal, the (100) surface 11 which is a smooth surface is a surface having poor wettability with respect to the binder, while the (111) surface 12 which is a rough surface is wettable with respect to the binder. It is a good aspect. For example, as shown in FIG. 2B, the (100) surface 10 which is a smooth surface has a contact angle with the vitrified bond which is the binder 21 of about 115 ° (see angle B), and has poor wettability. On the other hand, as shown in FIG. 2A, the rough (111) surface 12 has a contact angle with the vitrified bond, which is the binder 21, of about 25 ° (see angle A), and has good wettability. Excellent. In this abrasive grain 10, at least 30% of the entire surface area is constituted by the (111) face 12 which is a rough surface. Therefore, as shown in FIG. Thus, when the grindstone 20 is formed, the (111) surface 12, which is the rough surface of the abrasive grain 10, is firmly fixed to the binder 21, and the grindstone 20 that does not easily fall off the binder 21 can be obtained. Such a grindstone 20 is a grindstone 20 suitable for high-efficiency grinding because the abrasive grains 10 are excellent in rigidity, wear resistance and cleaving properties, and are difficult to fall off.

  Further, the (111) plane 12 of the CBN crystal is a plane having a higher protrusion than the (100) plane 11. Specifically, the height of the protrusion on the (100) surface 11 is about Ry 0.100 to 0.200 μm (actual value: Ry 0.170 μm), whereas the protrusion on the (111) surface 12 The maximum value is about Ry 1.000 to 2.000 μm (actual value: Ry 1.640 μm). Therefore, by setting at least 30% of the entire surface area of the abrasive grains 10 as the (111) plane 12, the projections on the (111) plane 12 can be reliably functioned as anchors for the binder 21, and the abrasive grains 10 The binder 21 can be made even more difficult to drop off.

  By the way, when forming the grindstone 20 using the said abrasive grain 10, what is necessary is just to shape | mold and bake into a desired shape using the said abrasive grain 10 and appropriate binders 21, such as a vitrified bond, for example. . Here, by adhering the grindstone 20 to the outer peripheral surface of the base formed in a disk shape with steel or the like, the grindstone 20, particularly the abrasive grain 10, is excellent in rigidity, wear resistance and cleavage properties on the outer peripheral surface. Moreover, it is possible to form a grinding wheel having a grinding wheel 20 suitable for high-efficiency grinding that is difficult to fall off.

  Although it is desirable to use the abrasive grains 10 that satisfy all the various requirements of the present invention as all the abrasive grains for forming the grindstone 20, there are some abrasive grains that do not satisfy the various requirements of the present invention. However, a grindstone suitable for high-efficiency grinding can be obtained. For example, if the abrasive grains 10 satisfying the various requirements of the present invention are 50% or more of the whole, preferably 70% or more, more preferably 90% or more, the grindstone 20 suitable for high-efficiency grinding can be obtained. .

  Various requirements of the present invention can be set as an average value of the entire abrasive grains 10 used to form one grindstone 20.

  Further, with respect to the surface of one abrasive grain 10, one of the smooth surface (100) surface 11 or the rough surface (111) surface 12 is at least 50%, 60%, or 70% of the entire surface area. You may make it occupy half or more of the whole surface area. In this case, if the remainder of the entire surface area of the abrasive grains 10 is occupied by at least 30% of the entire surface area by the other of the (100) surface 11 which is a smooth surface or the (111) surface 12 which is a rough surface. Good.

Finally, a comparative example of the grindstone according to the present invention and a conventional grindstone will be described below. In the following comparative example, a grindstone was manufactured using C120 abrasive grains of # 120, with vitrified bond as a binder, and C (concentration) = 200. Here, in the grindstone according to the present invention, the abrasive grains according to the present invention configured as described above are used, and in the conventional grindstone, most of the surface is composed of (100) faces, and the surface roughness is Ra0. Abrasive grains having a size of 01 to 0.05 μm were used. In addition, with a carburized hardened material of SCr420 and a surface hardness of HRC60, the grinding wheel peripheral speed is set to 120 m / s, the grinding efficiency is set to 37 mm ³ / mm · s, and the grinding amount is set by a cylindrical grinder. As a result, cylindrical plunge grinding up to 30000 mm ³ / mm was performed. Further, an emulsion was used as the coolant.

  In the conventional grindstone, the processing accuracy of the surface roughness of the workpiece has been reduced by about 15% from the beginning of the processing, whereas in the grindstone according to the present invention, only about 5% has been reduced from the beginning of the processing, and advanced processing is performed. The accuracy could be maintained.

  Further, regarding the wear amount of the grindstone, the grindstone according to the present invention was able to reduce the wear amount of the grindstone by about 20% as compared with the conventional grindstone.

It is a perspective view which shows an example of the abrasive grain which concerns on this invention. (A) is explanatory drawing which shows the wettability of a (111) surface and a binder, (b) is explanatory drawing which shows the wettability of a (100) surface and a binder.

Explanation of symbols

10 Abrasive grain 11 Smooth surface ((100) surface)
12 Rough surface ((111) surface)
13 Other surface 20 Grinding wheel 21 Binder

Claims (4)

A smooth surface with a surface roughness of Ra 0.01 to 0.05 μm occupies at least 30% of the entire surface area,
An abrasive characterized in that a rough surface having a surface roughness of Ra 0.06 to 0.20 μm occupies at least 30% of the entire surface area. Abrasive grains are formed of CBN (cubic boron nitride), a smooth surface with a surface roughness of Ra 0.01 to 0.05 μm occupies at least 30% of the entire surface area, and a surface roughness of Ra 0.06 to 020 μm. Abrasive grains whose surface occupies at least 30% of the entire surface area,
A grindstone wherein the binder is a vitrified bond. Formed by CBN (cubic boron nitride),
The (100) plane indicated by the Miller index occupies at least 30% of the entire surface area,
Abrasive grains characterized in that the (111) plane represented by the Miller index occupies at least 30% of the entire surface area. The abrasive grains are formed of CBN (cubic boron nitride), the (100) plane indicated by the Miller index occupies at least 30% of the entire surface area, and the (111) plane indicated by the Miller index occupies at least 30% of the entire surface area. Abrasive grains,
A grindstone wherein the binder is a vitrified bond.

Images