JPH08132349A - Grinding tool - Google Patents

Abstract

PURPOSE: To realize the uniform wear of a grinding material layer without reducing the biting-in force of the grinding material layer by forming the outer periphery surface portion out of the grinding material layer of a comparatively hard grinding material layer, forming the inner periphery surface portion out of a comparatively soft grinding material layer. CONSTITUTION: A hard layer 2 is formed at the outer periphery portion of a grinding material layer 1, and a soft layer 3 is formed at the inner periphery portion of the grinding material layer 1. Grooves 4 for distributing cooling water that is to be discharged through the center opening 5 of the grinding material layer 1 onto the whole surface of the grinding material layer 1 are formed. The outer periphery surface portion consisting of the hard layer 2 is made so as to occupy the approximate 20-40% of the radius of the grinding material layer 1, and the portion of the inner periphery surface is made so as to occupy the rest of the whole surface area of the grinding material layer 1. In the case of being smaller than 20%, the effect of forming the hard layer 2 at the outer periphery is small, and in the case of being larger than 40%, the ratio of the hard layer 2 is too high, and sharpness is reduced. As a result, at the rotary speed of 2000-4000rpm, the wear degree of the outer periphery surface portion of the hard layer 2 can be made approximately the same as the wear degree of the inner periphery surface portion.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to polishing tools for polishing the surface of hard and brittle materials such as stone.

[0002]

2. Description of the Related Art Conventionally, as a polishing tool for polishing a surface of a stone material, as shown in FIG. 4 showing a bird's-eye view and FIG. 5 showing a sectional structure of an abrasive layer 1, diamond abrasive grains, CBN abrasive grains, etc. An abrasive material layer 1 is formed from an abrasive grain and a thermosetting resin bond such as phenol resin or modified phenol resin, and a groove 4 for flowing cooling water is provided on the surface of the abrasive material layer 1 and the abrasive material layer 1 is formed. The structure in which the surface fastener 6 is attached via the backup sheet 7, and the surface fastener base material 8 attached to the flange attached to the output shaft of the air tool or the electric tool.
There is also a type in which it is fixed by means of polishing and is supplied while supplying cooling water from the shaft center hole 8.

[0003]

However, in the polishing tool having such a structure, the peripheral speed of the outer peripheral portion of the abrasive layer 1 is faster than that of the inner peripheral portion thereof, and the outer peripheral portion of the abrasive layer is rapidly worn. Due to the abrasion of the outer peripheral portion of the abrasive layer, the cutting of the outer peripheral portion into the work material is remarkably reduced, the working time is extended, and the workability is deteriorated. Further, if it is continued to be used as it is, the backup sheet and the surface fastener on the back of the outer peripheral portion of the abrasive layer may be damaged. Further, even though the abrasive layer remains on the inner peripheral portion, wear of the outer peripheral portion causes the tool itself to become unusable and shortens the service life.

An object of the present invention is to eliminate the drawbacks of the polishing tool, and to provide a polishing tool in which the abrasive layer is uniformly worn without reducing the biting force of the abrasive layer.

[0005]

SUMMARY OF THE INVENTION The present invention is a polishing tool having a structure in which a disc-shaped abrasive material layer is pasted with a surface fastener via a backup sheet, and the abrasive material layer has a relatively hard outer peripheral surface portion. Of the abrasive material layer and the inner peripheral surface portion is formed of a relatively soft abrasive material layer.

The outer peripheral surface portion of the hard layer occupies approximately 20% to 40% of the radius of the abrasive layer, and the inner peripheral surface portion occupies the rest of the total surface area of the abrasive layer. If it is less than 20%, the effect of forming a hard layer on the outer periphery is small, and if it is more than 40%, the ratio of the hard layer is too high and the sharpness is reduced.

The hard layer on the outer peripheral surface portion uses a binder having a high wear resistance of 10 to 50% as compared with the soft layer on the inner peripheral surface portion, or
It is formed by increasing the diamond abrasive concentration by 10 to 50%.

[0008]

The wear degree of the outer peripheral surface portion of the hard layer can be made substantially the same as the wear degree of the inner peripheral surface portion under the normal rotation speed of the polishing tool of 2000 to 4000 rpm.

[0009]

【Example】

Example 1 FIG. 1 is a view of an abrasive material layer 1 of a polishing tool to which the present invention is applied as seen from the surface, and FIG. 2 shows a cross section thereof.

In the figure, 2 is a hard layer formed on the outer peripheral portion of the abrasive layer 1, 3 is a soft layer formed on the inner peripheral portion, and 4 is emitted from the central opening 5. A groove in which cooling water is formed on the entire surface of the abrasive layer 1 is shown. The grooves 4 can be formed in any shape, but in the case of the embodiment of the present invention, six grooves are concentric with the central opening 4 and are radial and with respect to the rotational direction R of the tool indicated by the arrow. Thus, each is formed in a plurality of arcuate shapes in opposite directions. As shown in FIG. 2, the thickness a of the abrasive layer 1 is uniformly formed to be 2 mm, and the lower surface of the abrasive layer 1 has a thickness b through a backup sheet.
Is attached to the surface fastener 5 of 3 mm.

The outer peripheral hard layer 2 has a radius r of the abrasive layer 1.
Was 40 mm, the width r ₂ was set to 30% of the radius r, and the remaining inner peripheral portion 3 was left with the central opening 5 to form the soft layer 3.

For comparison, a polishing tool equipped with an abrasive layer having a single composition was prepared.

In the case of this example, the hard layer and the soft layer were changed depending on the composition of the binder.

Table 1 shows the composition of the binder. In addition,
In this case, the degree of concentration of the diamond abrasive was the same on the inner peripheral portion and the outer peripheral portion.

In the table, GC represents SiC, and it was compounded so that its wear resistance would be 130% of the usual value. The abrasion resistance in the table is a value obtained by indexing the value of the grinding ratio represented by the amount of material to be deleted (g) / abrasive material layer abrasion amount (g) after a stone polishing test.

As a comparative example, FIG.
A tool was used in which the entire surface of the abrasive layer 1 shown in (1) was a soft layer having an inner peripheral portion according to the present invention.

Example 2 As the peripheral hard layer binder, the same hard binder as in Example 1 was used, and the one in which the concentration of the abrasive was increased was adjusted to obtain the same FIG. 1 as in Example 1. The polishing tool shown was created.
Table 2 shows the configurations of the hard layer and the soft layer.

[0018]

[Table 1]

[Table 2] A polishing test was conducted under the following conditions until the polishing tools obtained in each of the above examples were used up.

Polishing Test Conditions Work Material: Tianshan Granite Polishing Tool Outer Diameter: φ80 Polishing Machine: Air Tool Rotation Speed: 1000 rpm Polishing Method: Manual, Wet Polishing Polishing Tool Grain Size: # 500 Table 3 shows each example of the present invention. 7 shows the results of measuring the thickness of the outer peripheral portion and the inner peripheral portion of the abrasive layer after the polishing test in FIG.

* Tests were carried out until the rest of the outer peripheral portion was 0.1 mm (almost completely used up). As a result, the conventional example cannot be used continuously even though the inner peripheral portion remains 0.8 mm.

[0021]

[Table 3] As shown in the table, it can be seen that the degree of wear of the abrasive layer according to the example of the present invention is more uniform in the outer peripheral portion and the inner peripheral portion as compared with the conventional one given as the comparative example.

FIG. 3 shows the results of investigations of the respective durability. In Example 1, the outer peripheral portion and the inner peripheral portion were worn almost uniformly,
Processing of 15 m ² was possible. On the other hand, in the comparative example, the thickness of the inner peripheral portion was 9.5 although the thickness remained 0.8 mm.
At m ² , the outer circumference was worn out and the life was reached.

Example 2 showed almost the same tendency as Example 1, but the outer and inner peripheral thicknesses were worn to be approximately equal, and the thickness was 17 m.
It was possible to process ² .

[0024]

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

(1) There is no early wear of the outer peripheral portion formed by the abrasive layer having high hardness, and the wear is substantially uniform with the inner peripheral portion, and the tool durability is improved.

(2) Since the outer peripheral portion and the inner peripheral portion are evenly worn, the contact area between the work material and the abrasive layer is large and the workability is improved.

(3) Since it is possible to maintain the cutting of the outer peripheral portion into the work material, a stable sharpness can be obtained from the beginning to the end.

(4) Since the outer peripheral portion and the inner peripheral portion are worn in a well-balanced manner, no abnormal vibration is generated during use.

[Brief description of drawings]

FIG. 1 shows a surface state of an abrasive layer of a polishing tool according to an embodiment of the present invention.

FIG. 2 shows a sectional structure of the polishing tool shown in FIG.

FIG. 3 shows the test results of the polishing tool of the present invention together with the case of a comparative example.

FIG. 4 shows an overhead view of a conventional polishing tool.

FIG. 5 shows a cross-sectional structure of a conventional polishing tool.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Abrasive material layer 2 Hard layer of outer peripheral portion 3 Soft layer of inner peripheral portion 4 Surface groove 5 Center opening 6 Surface fastener 7 Backup sheet 8 Surface fastener base material

Claims (3)

[Claims] 1. A polishing tool having a structure in which a disc-shaped abrasive layer is pasted with a surface fastener via a backup sheet, wherein the abrasive layer is formed from a relatively hard abrasive layer at an outer peripheral surface portion, A polishing tool having an inner peripheral surface portion formed of a relatively soft abrasive layer. 2. A polishing tool characterized in that the width of an outer peripheral surface portion of a hard layer in an abrasive layer occupies approximately 20% to 40% of the radius of the abrasive layer. 3. A hard layer in the outer peripheral surface portion of the abrasive layer is made of a binder having a high wear resistance of 10 to 50% as compared with a soft layer in the inner peripheral surface portion, or the outer peripheral surface portion is internally Compared with the soft layer on the peripheral surface, the diamond abrasive concentration is 10
A polishing tool characterized by being formed by increasing it by -50%.