JP2000094341A - Diamond offset grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the exposure of a substrate on an outer peripheral side caused by the wear of the outer peripheral side of an abrasive material layer and maintain the sharpness by forming an intermediate layer having less content of abrasive grain and filler than the abrasive material layer between a side face of the substrate and the abrasive material layer. SOLUTION: This offset grinding wheel is constituted in such a way that an abrasive material layer 12 and an intermediate layer 13 are attached to a side face 11a of an offset type substrate 11 by a simultaneous molding method with substrate material powder. Both of the abrasive material layer 12 and the intermediate layer 13 are composed of diamond abrasive grains and GC, a chromium oxide (filler), and a phenol resin (binder). The intermediate layer 13 has less content of diamond abrasive grains and GC abrasive grains when compared with that of the abrasive material layer 12, its total content is 40 to 70%, and the content of the phenol resin is increased. Moreover, a thickness of the intermediate layer 13 is 1 to 2 mm, and a boundary face between the intermediate layer 13 and the abrasive material layer 12 is inclined by 2 to 20 degrees from the inside of a substrate toward the outside thereof in the direction in which the abrasive material layer becomes thick. It is possible to prolong the service life of the grinding wheel by providing the intermediate layer 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond offset grinding wheel used for processing a surface of a highly brittle material such as stone or glass.

[0002]

2. Description of the Related Art Conventionally, offset type grindstones have been used for surface processing of highly brittle materials such as stone and glass. The basic structure of the offset-type grindstone is such that an abrasive layer is formed on a side surface of a substrate having an offset portion in the center.
The abrasive layer is diamond or CBN (cubic boron nitride)
General abrasive grains such as super-abrasive grains such as silicon carbide-based abrasive grains (GC, C) and alumina-based abrasive grains (A, WA);
A typical one is composed of a filler such as graphite powder and a binder such as phenol resin.

[0003] The offset type grindstone is generally mounted on a disk grinder and used in a dry state. One of the problems in using the offset type grinding stone is the problem of uneven wear of the abrasive layer and the problem of reduced sharpness.

When an offset-type grindstone is mounted on a hand-held disc grinder and used, a so-called tilting method, in which cutting is performed by inclining a grindstone axis, is often used due to restrictions on cutting resistance and electric motor output. In addition, it is often used for processing a curved surface or chamfering a corner. In the tilting, the curved surface processing, and the chamfering, the outer peripheral side of the abrasive layer wears faster than the inner peripheral side. For this reason, while the abrasive layer still remains on the inner peripheral side, the abrasive layer disappears due to wear on the outer peripheral side, and the substrate is exposed, causing burns due to a sharp decrease in sharpness,
There is a problem that the life of the grinding wheel is shortened.

As an improved grindstone for solving this problem, Japanese Utility Model Application Laid-Open No. 60-183159 discloses an offset grindstone using a resinoid grindstone as a substrate. According to this grindstone, the resinoid grindstone portion is worn together with the sponge grindstone portion, so that the sponge grindstone portion can be effectively used up to its inner peripheral portion.

Further, Japanese Patent Publication No. 5-2469 discloses an offset type grinding wheel in which an auxiliary grinding wheel is provided between the lower surface of the abrasive layer on the outer peripheral side and the outer peripheral portion of the substrate. According to this whetstone, it is said that the whetstone can be used until the auxiliary whetstone is completely worn, even after the outer peripheral abrasive material layer is worn away, thereby extending the life of the whetstone.

Japanese Patent Application Laid-Open No. 2-250775 discloses an offset type grinding wheel in which the thickness of the outer peripheral side of the abrasive layer is made larger than that of the inner peripheral side, and the thickness of the outer peripheral side of the substrate is made thinner than the inner peripheral side. Has been described. According to this whetstone, when the whetstone is pressed against the processing surface of the workpiece with an inclination, the whetstone is curved with almost the same radius of curvature from the inner peripheral side to the outer peripheral side, and the contact surface with the workpiece is widened, It is said that grinding can be performed efficiently with little wear of the abrasive layer.

[0008]

However, the offset type grindstone disclosed in Japanese Utility Model Laid-Open No. 60-183159 has a problem in strength as a substrate because the substrate itself is a resinoid grindstone. Since the polishing power of the resinoid grindstone is set to be equal to that of the sponge grindstone, the result is the same as the case where the sponge grindstone is thickened.

Further, the auxiliary grinding wheel having excellent mechanical strength used for the offset type grinding wheel described in Japanese Patent Publication No. 5-2469 has a small molding shrinkage like the abrasive layer, and a shrinkage ratio with the substrate. It is greatly warped by the difference. For this reason, there occurs a problem that the wobble and vibration of the grinding wheel increase during processing, and the processing efficiency decreases.

The offset-type grindstone disclosed in Japanese Patent Application Laid-Open No. 2-250775 has an effect of reducing local wear of the abrasive material layer due to a wider contact surface with a workpiece during tilting. However, if the thickness of the outer peripheral side of the abrasive layer is made thicker than the inner peripheral side, and the thickness of the outer peripheral side of the substrate is made thinner than the inner peripheral side, and pressure molding is performed, the shrinkage ratio between the abrasive layer and the substrate It is greatly warped by the difference. For this reason, there occurs a problem that the wobble and vibration of the grinding wheel increase during processing, and the processing efficiency decreases.

The problem to be solved by the present invention is to suppress exposure of the substrate on the outer peripheral side caused by abrasion of the outer peripheral side of the abrasive layer in the offset grinding wheel, maintain sharpness, and prevent burning of the grindstone and the workpiece. Another object of the present invention is to prevent warpage of the abrasive layer during molding and to reduce wobble and vibration during grinding.

[0012]

According to the present invention, there is provided an offset grinding wheel having an abrasive layer formed on a side surface of an offset type substrate, wherein the abrasive layer is disposed between the side surface of the substrate and the abrasive layer. An intermediate layer having a small content of abrasive grains and filler is formed.

By forming an intermediate layer between the side surface of the substrate and the abrasive layer, the outer periphery of the abrasive layer is worn faster than the inner periphery by repeating the tilting process, the curved surface process, and the chamfering process. Even if the abrasive material layer is not present, the sharpness can be maintained because the intermediate layer appears. Therefore, the workpiece and the grindstone are not burned due to the decrease in sharpness, and the life is not shortened. Further, since the difference in shrinkage between the abrasive layer and the substrate can be reduced by the intermediate layer, the occurrence of wobble of the grinding wheel can be suppressed.

The total content of the abrasive and the filler in the intermediate layer is 40 to 70% of the total content of the abrasive and the filler in the abrasive layer.
It is desirable to be within the range. Even if the total content of the abrasive grains and the filler in the intermediate layer is more or less than this range, the difference in the shrinkage rate during the molding of the abrasive layer and the substrate cannot be reduced, and the effect of preventing the warping of the grinding wheel. There is no. That is, when the total content of the abrasive grains and the filler in the intermediate layer is less than 40% of the total content of the abrasive grains and the filler in the abrasive layer, the shrinkage becomes large and becomes similar to the physical properties of the substrate. If it exceeds, the shrinkage becomes small and becomes similar to the physical properties of the abrasive material layer, and the effect of preventing warpage is reduced.

Here, the boundary surface between the intermediate layer and the abrasive layer can be inclined in a direction in which the abrasive layer becomes thicker from the inner periphery to the outer periphery of the substrate. This inclination can be formed by making the outer peripheral side of the substrate thinner than the inner peripheral side, and the inclination angle is desirably in the range of 2 to 10 degrees. By providing such an inclination, even when the outer peripheral side of the abrasive layer is quickly worn, the timing of reaching the intermediate layer is substantially the same on both the outer peripheral side and the inner peripheral side.

The thickness of the intermediate layer should be at least 1 mm or more as an effective thickness for taking into account the in-plane variation of the wear of the abrasive layer and reducing the difference in shrinkage between the abrasive layer and the substrate. Is desirable. The upper limit of the thickness does not need to be particularly limited, but 2 mm is sufficient if the difference in the degree of wear between the outer peripheral side and the inner peripheral side of the abrasive material layer is sufficient.

[0017]

FIG. 1 is a plan view of an offset grinding wheel according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

The offset grinding wheel 10 of the present embodiment comprises:
An abrasive layer 12 and an intermediate layer 13 are attached to a side surface 11a of an offset type substrate 11 by a simultaneous molding method with a substrate material powder. Abrasive layer 12 and intermediate layer 13
Is divided into a large number of regions by a groove 12a which is divided into 15 in the circumferential direction and grooves 12b and 12c which further divide each divided region into eight.

Both the abrasive layer 12 and the intermediate layer 13
It consists of diamond abrasive, GC, chromium oxide (filler), and phenolic resin (binder).
As shown in FIG. In the present embodiment, the intermediate layer 13 has a lower content of diamond abrasive grains and GC abrasive grains than the abrasive material layer 12, and has a higher phenol resin content. As a result, the intermediate layer 13 has slightly lower grinding performance than the abrasive layer 12, but the shrinkage during molding has an intermediate value between the substrate and the abrasive layer.

[0020]

[Table 1]

By having such an intermediate layer 13, the difference in shrinkage between the abrasive material layer and the substrate during the manufacture of the grinding wheel can be alleviated, and the occurrence of warpage of the grinding wheel can be suppressed. And vibration can be prevented.

The substrate 11 has a dish shape similar to that of a conventional offset grinding wheel, but in the present embodiment, the side surface 11a of the substrate 11 is directed downward in a downward slope. The intermediate layer 13 and the abrasive layer 12 are mounted on the inclined surface. Note that reference numeral 11b in FIG.
The hole indicated by is a mounting hole for mounting the offset cutting grindstone 10 to the rotating shaft of the disk grinder.
The dimensions of each part are as follows: the outer diameter of the substrate 11 is 99 mm, the width of the abrasive layer 12 in the radial direction of the substrate is 22.5 mm, the thickness of the inner peripheral end of the abrasive layer 12 is 3.5 mm, and the thickness of the intermediate layer is 1 mm. .

The inclination angle θ of the upper surface of the outer peripheral portion of the substrate 11 is 5 degrees in this embodiment. By providing a slope on the upper surface of the outer peripheral portion of the substrate 11 and making the thickness of the intermediate layer 13 1 mm over the entire surface, the outer peripheral side of the abrasive layer 12 is thicker than the inner peripheral side, and the outer peripheral side and the inner peripheral side are almost It will be exhausted at the same time.

As described above, the thickness of the outer peripheral side of the abrasive layer 12 is increased so that the outer peripheral side and the inner peripheral side are completely consumed at substantially the same time, and the intermediate layer 13 is provided.
Even if tilting, curved surface processing, and chamfering are repeated, the abrasive layer is still left on the inner peripheral side as before, but it will not be disabled early due to wear on the outer peripheral side. Life can be extended.

In the above embodiment, the substrate 1
Although the inclined surface is provided on the entire surface from the inner periphery to the outer periphery of the first side surface 11a, the inclined surface may be provided only on the outer periphery side (see FIG. 3A). It is also possible to make it easy to machine the details of the workpiece by inclining (see FIG. 3B).

Experimental Example In order to confirm the effect of the present invention, a grindstone of the present embodiment shown in FIG. 1 (inventive product) and a grindstone having the same shape as this grindstone but without an intermediate layer (comparative product) A processing experiment was carried out under the following processing conditions using

Processing conditions: Processing machine: electric disk grinder ・ Rotational speed: 12000 rpm ・ Workpiece: Tenyama granite curved surface and flat surface

Table 2 shows the experimental results.

[Table 2]

As shown in Table 2, the invention product had significantly smaller lateral runout and warpage of the abrasive layer than the comparative product, and the life of the grinding wheel was improved by about 1.6 times. In addition, the grinding efficiency of the comparative product is greatly reduced when the abrasive layer disappears, and the workpiece and the grindstone are scorched, whereas the invention product maintains the grinding efficiency even when the abrasive layer is worn. No scorching occurred on the workpiece or the grindstone.

[0030]

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

(1) By forming an intermediate layer between the side surface of the substrate and the abrasive material layer, the content of the abrasive and the filler is smaller than that of the abrasive material layer, tilting, curved surface processing, and chamfering can be performed. Even if it is repeated, the abrasive material layer is still left on the inner peripheral side as in the related art, but it is not possible to use the abrasive material at an early stage due to wear on the outer peripheral side, and the life of the grindstone can be extended.

(2) By providing the intermediate layer, it is possible to reduce the difference in the shrinkage ratio between the abrasive material layer and the substrate during molding, whereby the deflection and warpage of the grinding stone can be reduced, and Vibration and abnormal early abrasion of the abrasive layer caused by the vibration can be prevented.

(3) By providing the intermediate layer, even if the abrasive layer is worn, the intermediate layer appears and can prevent a decrease in the grinding efficiency, and can prevent the burn of the workpiece or the grindstone due to the decrease of the sharpness. Can be prevented, and the life of the grinding wheel can be improved.

(4) Abrasion of the boundary between the intermediate layer and the abrasive layer in the direction in which the abrasive layer becomes thicker from the inner periphery to the outer periphery of the substrate causes wear on the outer peripheral side and the inner peripheral side of the abrasive layer. And the life of the grinding wheel can be improved.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a cross-sectional view showing another example of a grindstone shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Offset grinding wheel 11 Substrate 11a Side surface 11b Mounting hole 12 Abrasive material layer 12a-12c Groove 13 Intermediate layer θ Tilt angle

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Ueno 210, Takeshi, Tanushimaru-cho, Ukiha-gun, Fukuoka Prefecture Noritake Diamond Co., Ltd. F-term (reference) 3C063 AA02 AB05 BA02 BA21 BA24 BA33 BB02 BB21 BC03 FF03 FF09 FF11 FF23

Claims (5)

[Claims] 1. An offset grinding wheel having an abrasive layer formed on a side surface of an offset-type substrate, wherein the content of abrasive grains and filler between the side surface of the substrate and the abrasive layer is greater than that of the abrasive layer. A diamond offset grinding wheel characterized by forming an intermediate layer with a small number of layers. 2. The total content of the abrasive grains and the filler in the intermediate layer is 40 to 70 times the total content of the abrasive grains and the filler in the abrasive layer.
%. The diamond offset grinding wheel according to claim 1, wherein 3. The diamond offset grinding according to claim 1, wherein a boundary surface between said intermediate layer and said abrasive layer is inclined in a direction in which said abrasive layer becomes thicker from an inner periphery to an outer periphery of said substrate. Whetstone. 4. The diamond offset grinding wheel according to claim 3, wherein an inclination angle of the boundary surface is 2 to 10 degrees. 5. The diamond offset grinding wheel according to claim 1, wherein said intermediate layer has a thickness of 1 to 2 mm.