JP3086668B2 - Vitrified bond super abrasive whetstone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive used for forming a grindstone having a superabrasive grain layer formed by bonding superabrasive grains such as CBN (cubic boron nitride) and diamond by vitrified bond; The present invention relates to bonded superabrasive grinding wheels. The superabrasive grindstone fixed and bonded is used for grinding metal or non-metal members.

[0002]

2. Description of the Related Art As this kind of adhesive, a heat-curable or room-temperature-curable epoxy resin-based adhesive having relatively high adhesive strength and excellent chemical resistance is known.

[0003]

However, the epoxy resin adhesive has a coefficient of thermal expansion of about ^{80.times.10.sup.-6} / .degree.
Steel (S45C) base metal of about 2 × 10 ⁻⁶ / ° C., 2 to 7 ×
It is much larger than any of the superabrasive layers of CBN vitrified bond at about 10 ^-6 / ° C. Therefore, when the superabrasive layer is adhered to the base metal with a heat-curable adhesive and heated and fixed, internal stress accumulates in the adhesive layer and there is a concern that the superabrasive layer may come off.

[0004] In the case of a room temperature curing adhesive, there is no problem at the time of fixing by heating. However, when grinding is performed at a high speed, a processing heat is generated and the adhesive layer is also exposed to heat. There is a concern that the chip may be detached due to the difference between the chips. In addition, the thickness of the adhesive layer is sufficiently large for the bonding operation, and it is difficult to form the adhesive layer. Therefore, the stress due to the difference in the thermal expansion coefficient cannot be absorbed. There is a problem that the grinding liquid that penetrates from the abrasive layer swells the entire thin adhesive layer, thereby deteriorating the adhesive strength. Further, in the case of a thin adhesive layer, there is also a concern that the adhesive strength is not uniform and insufficient, and the adhesive strength is not sufficient, and the superabrasive layer is likely to come off.

[0005] In order to reduce the coefficient of thermal expansion of the adhesive, it has been attempted to add a filler to the adhesive, but it has not been known yet.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and has the following features. That is, one of them is an epoxy resin or an acrylic resin adhesive having a coefficient of thermal expansion of 10 × 10 ⁻⁶ / ° C. or less, and an average particle diameter is substantially constant within a range of 30 to 100 μm. One or two or more types of nitrides and diamonds are added and mixed at 0.1 to 5 % by volume to constitute a mixed adhesive. As a result, the thickness of the adhesive layer at least corresponding to the substantially constant average particle diameter added is ensured, and the coefficient of thermal expansion can be reduced.

[0007] Another is that the above additive mixture is further added with the same additive having an average particle size in the range of 3 to 29 µm in 10 to 30 volumes.
% . Thereby, the thermal expansion coefficient of the adhesive can be further reduced to 60 × 10 ⁻⁶ / ° C. or less.

Another one is a super-abrasive grindstone in which an adhesive layer having a thickness of 30 μm or more is formed using the above-mentioned mixed adhesive, and a super-abrasive grain layer of vitrified bond is integrally fixed to a base metal. To provide.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments will be described together with comparative examples in the section of Examples.

[0010]

DETAILED DESCRIPTION FIG. 1, the outer diameter D ₁ is about 334 mm, the thickness T is 16 mm, hole diameter H is 127mm made of steel (S45C) to the outer peripheral end face of the base metal 1, as shown in FIG. 2 previously prepared CB
This is a vitrified bond CBN grindstone in which 28 chips 2 of a superabrasive grain layer formed by bonding N with vitrified are closely adhered and fixed. The outer diameter D ₂ of the whetstone is 350 mm
The length L of the chip 2 of each superabrasive layer is 40 mm, the width W is 16 mm, and the thickness X is 8 mm. In addition, this thickness 8mm
In the middle, about 4 mm on the bonding side, a so-called intermediate layer may be used by reducing the mixing ratio of abrasive grains or by changing to a filler.

As shown in Table 1, the superabrasive layer was bonded and fixed to the base metal 1 by adding the commercially available adhesives of Comparative Examples 1 and 2 and an additive mixture (additive mixture) thereto. Examples 1, 2, 3, and 4 were used.

[0012]

[Table 1]

As can be seen from Table 1, the thickness of the adhesive layer varies greatly depending on the presence or absence of the additive mixture and the particle size of the additive mixture, but the thickness of each of the examples is larger than that of the comparative example. This is preferable in terms of uniformity of adhesive strength and absorption of stress against heat change.

Then, in order to confirm the adhesive strength, each super-abrasive grindstone was immersed in an emulsion-based grinding fluid (diluted 50-fold, PH 9.4) at 80 ° C. for 2 weeks after production of the grindstone. The following tests were performed for each of the items.

That is, the tip 2 of the superabrasive layer at the outer peripheral end of the grindstone
The upper and lower surfaces of the grindstone base metal 1 are held by a disc-shaped holding jig while leaving the periphery of the fixed portion of the grinding wheel, and the bending force measuring piece is brought into contact with the upper surface of the chip 2 of the superabrasive grain layer, and the piece is removed. The chip 2 was pressed in a direction parallel to the bonding surface, and the force until the chip 2 came off was measured.
As a result, before and after immersion in the grinding fluid, all of the examples showed higher adhesive strength than the comparative example.

In particular, in the comparative examples, it was remarkably evident that the adhesive strength was significantly reduced by immersion in the grinding fluid, while that of the examples was slight. This is because the chip 2 of the superabrasive layer is a porous vitrified bond, so that the grinding fluid penetrates from the chip and swells the entire thin adhesive layer, thereby lowering the adhesive strength.
This is probably because in the thick adhesive layer, the swelling is partially stopped and the adhesive strength is maintained. FIG. 3 shows the comparison. The reason why N is as large as 15 is that a large number of the strength measurement points were measured at two or more places, and a large number of the third examples which exhibited particularly stable high strength were manufactured.

As can be understood from FIG. 3, in the example, before the immersion in the grinding fluid, the strength was improved by 70% or more compared to the comparative example.
Although there is a strength reduction of more than 0%, that of the example is about 13%. It is thought that the above-mentioned improvement in strength is due to the fact that the added mixture strengthens the adhesive layer and reduces the stress by increasing the thickness, and the adhesive is mixed into the porous surface of the vitrified bond to exert the anchor effect. Can be

Considering the amount of the additive mixture, the thickness of the adhesive layer, and the shear strength from the examples and comparative examples, it is considered that the relationship is as shown in FIGS. Therefore, in order to ensure the thickness of the adhesive layer is about 30 μm or more, it is necessary that the particle size of the additive mixture contains those having an average particle diameter of 30 μm or more, and the amount is preferably within the above range. . In addition, as an additive admixture, a diamond having a low coefficient of thermal expansion, a high chemical resistance, a good wettability with an adhesive, and easily obtainable fine particles, CB
N is excellent, but expensive, so Al ₂ O ₃ , WC, T
Oxides, carbides, nitrides, or composites thereof, such as those obtained by sintering and pulverizing iN, may be used.

In the embodiment, the vitrified bond CBN chip is bonded and fixed with an epoxy resin adhesive, but an acrylic resin having excellent fixing force, oil resistance and weather resistance may be used instead of the epoxy resin. it can. Also, if necessary, it is needless to say that diamond can be used as the superabrasive grain, and the shape and size of the chip can be freely selected. Other metal, ceramic, resin, or a composite material thereof is used as the base metal material. It is also possible.

[0020]

According to the present invention, since the vitrified bond superabrasive layer is firmly adhered and fixed to the grindstone base according to the present invention, it can sufficiently withstand high-speed grinding. In addition, there is little deterioration of the adhesive strength in the grinding fluid, so that the life is long.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of an example and a comparative example grindstone.

2A is a top view of a chip of a vitrified bond superabrasive layer, and FIG. 2B is a side view thereof.

FIG. 3 is a table showing a comparison of adhesive strength.

FIG. 4 is a table for explaining the relationship between the amount of an admixture and the shear strength.

FIG. 5 is a table for explaining the relationship between the thickness of the adhesive layer and the shear strength.

[Explanation of symbols]

1 Base 2 Chip of vitrified superabrasive layer D ₁ Outer diameter of base D ₂ Outer diameter of superabrasive grindstone H Hole diameter of base T Thickness of base L Chip length W Tip width X Tip thickness

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshio Fukunishi 2-80, Hokita-cho, Sakai-shi, Osaka Inside Osaka Diamond Diamond Industry Co., Ltd. (56) References JP-A-63-283869 (JP, A) JP-A-2-168636 (JP, A) JP-A-56-147310 (JP, A) JP-A-9-227850 (JP, A) JP-A-6-226636 (JP, A) A) JP-A-7-122684 (JP, A) JP-A-62-153372 (JP, A) JP-A-57-83553 (JP, A) JP-A-5-339555 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) B24D 3/00-18/00 C09J 1/00-201/10

Claims (2)

(57) [Claims] 1. A superabrasive layer of vitrified bond is bonded
Adhered to the base metal by the adhesive layer formed by the agent
In the superabrasive grinding wheel, the adhesive is an epoxy resin-based adhesive having a coefficient of thermal expansion of 10 × 10 ^−6.
/ ℃ below, the average particle size is substantially constant within the range of 30 to 100 [mu] m, oxides, carbides, nitrides, one diamond, or two or more will be allowed to contain 0.1 to 5% by volume Wherein the adhesive layer has a thickness of 30 μm or more.
Super abrasive whetstone. 2. The adhesive further has a coefficient of thermal expansion of 10 × 1.
0 ^{-6 /} ° C. or less of oxides, carbides, nitrides, one diamond, or be two or more, an average particle diameter of 3 to 2
Those in the range of 9μm contain added 10-30 volume%
2. The superabrasive grinding wheel according to claim 1, wherein