JP2002030882A - Bit and boring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and excellently maintain the cutting performance of a granular whetstone layer segment. SOLUTION: A part of a grinding surface 23a of a granular whetstone layer segment 23 positioned at a bit rotating direction T side is formed into a projecting curved surface 23b formed so as to come closer to a pedestal 1 as it comes toward the bit rotating direction T. The projecting curved surface 23b is continuously formed to a fixing surface 1a to the granular whetstone layer segment 23. The boring by a bit 30 is performed by a dry type method using the loosened granular whetstones grains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bit used for forming a circular hole in a concrete structure or the like and a method for piercing the bit.

[0002]

2. Description of the Related Art As shown in FIG. 5, a bit 10 of this kind includes a base metal 1 having a cylindrical shape, a shaft 2 provided coaxially on the base end side of the base metal 1, 1 comprises a plurality of abrasive grain layer segments 3 made of a metal-bonded grindstone fixed at a constant interval in the circumferential direction to the tip of the shaft 1. The shaft portion 2 is connected to a driving device. Then, bit 1 is driven by the driving device.
0 is pressed against the work material W such as a concrete structure while rotating the work material W in the abrasive grain layer segment 3.
To form a cylindrical through-hole or hole. When drilling, the ground surface 3a at the tip of the abrasive layer segment 3
In order to suppress the heat generation of the shaft and promote the discharge of the cuttings, the shaft 2
The grinding medium 4 is continuously supplied into the bit 10 through the inner circumference of the grinding tool. As such a grinding medium 4, a grinding fluid such as water is generally used, and the workpiece W is drilled in a wet manner. At this time, the cutting fluid and the water are mixed and the sludge-like grinding fluid is discharged.However, it is difficult to collect all the discharged grinding fluid, and the surrounding environment is polluted. Causes a problem. In order to solve such a problem, Si is used as the grinding medium 4 instead of water.
It has been proposed to perform dry drilling using air together with free abrasive grains such as C and alumina. However, a grinding medium is provided at the interface between the grinding surface 3a at the tip of the abrasive grain layer segment 3 and the work material W. 4 is not supplied well, and most of the grinding medium 4 flows out from the gap between the respective abrasive grain layer segments 3 to the outer peripheral side,
The abrasive layer segment 3 is liable to be clogged, and has a disadvantage that the discharging ability of the swarf is deteriorated.

In addition to the above-mentioned bits, the following bits have been proposed. As shown in FIGS. 6 (a) and 6 (b), a bit 20 showing this example has an abrasive grain layer segment 13 fixed at regular intervals in the circumferential direction along the tip of a cylindrical base metal 1. In addition, a flat inclined surface 13b inclined toward the base metal 1 is formed in front of the grinding surface 13a of the abrasive grain layer segment 13 in the bit rotation direction T. In this case, since the inclined surface 13b is provided, the grinding medium 4 is guided to the inclined surface 13b during the drilling of the workpiece W so that the abrasive layer segment 1 is formed.
3 is supplied to the interface between the ground surface 13a and the workpiece W.

[0004]

However, since the boundary 13c between the grinding surface 13a and the inclined surface 13b is formed as a ridge line by the inclined surface 13b of the abrasive grain layer segment 13, the grinding surface 13a and the workpiece It is difficult to be supplied without being well involved in the interface with the material W. Further, the wall surface 13d that is substantially perpendicular to the rotation direction T of the bit 20 is
Is formed on the front side, the grinding medium 4 which tends to flow to the inclined surface 13b is blocked by the wall surface 13d, and the amount discharged to the outer peripheral side from the gap between the respective abrasive grain layer segments 13 is still small. Many. For these reasons, the amount of the grinding medium 4 flowing to the outer peripheral side increases, and the grinding surface 13a
The amount of the grinding medium 4 supplied to the interface between the workpiece and the workpiece W was still insufficient.

The present invention has been made in view of the above circumstances, and improves the supply of a grinding medium to a grinding surface of an abrasive layer segment to maintain the sharpness of the abrasive layer segment and prevent clogging. It is an object of the present invention to provide a bit and a drilling method that can perform the drilling.

[0006]

The present invention has the following features to attain the object mentioned above. That is, the bit according to claim 1 has a base metal having a cylindrical shape, and a number of abrasive layer segments fixed along the tip of the base metal, and is rotated around the axis of the base metal. In the bit, a portion of the ground surface of the abrasive grain layer segment, which is located on the front side in the bit rotation direction, has a convex curved surface approaching the base metal toward the front side in the rotation direction. With such a configuration, a part of the grinding medium flowing during the drilling of the work material is supplied to the interface between the grinding surface and the work material so as to be caught in the convex curved surface, Encourages the spontaneous cutting of the abrasive layer segments, always keeps the sharpness good,
The clogging can be prevented and the chip discharge property can be improved.

According to a second aspect of the present invention, in the bit of the first aspect, the convex curved surface extends to a surface of the base metal fixed to the abrasive grain layer segment. With such a configuration, a grinding medium is easily supplied to the interface between the ground surface and the work material at the time of drilling the work material, and a good and stable sharpness of the abrasive grain layer segment can be obtained for a long period of time.

According to the third aspect of the present invention, there is provided a drilling method.
Or a drilling method using a bit according to claim 2, wherein the bit is rotated around an axis to introduce free abrasive grains into the bit body while cutting each abrasive grain layer segment into a work material. The processing of the work material is performed while supplying the free abrasive grains between the ground surface of the abrasive grain layer segment and the work material. By using such a method, the free abrasive grains are supplied to the interface between the grinding surface and the work material in such a manner as to be rolled into the convex curved surface, and promote the spontaneous cutting of the abrasive grain layer segment to sharpen the sharpness. The effect of always keeping good and preventing clogging becomes particularly remarkable as compared with the conventional case.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the attached drawings, but the same or similar parts as those of the above-mentioned prior art will be denoted by the same reference numerals and description thereof will be omitted. FIG. 1 is a perspective view of a bit according to an embodiment of the present invention, FIG. 2 is a side view of the tip of the bit, and FIG. 3 is a front view of the tip of the bit.

A bit 30 according to an embodiment of the present invention is mainly used for dry cutting, and has a cylindrical base 1 and a small-diameter cylindrical shaft 2 formed coaxially at the base end thereof. As shown in FIG. 1, a plurality of abrasive grain layer segments 23 each having a substantially arc shape are arranged in a line in the circumferential direction of the base metal 1 at a predetermined distance L on the tip end side of the base 1, for example, by brazing or the like. It is fixed.

As shown in FIG. 2, the abrasive grain layer segment 23 has a flat grinding surface 23a used for drilling a work material.
A convex curved surface 23b is formed at a portion located on the front side in the bit rotation direction T so as to gradually approach the base metal 1 toward the front side in the bit rotation direction T. Further, the convex curved surface 23b is formed smoothly and continuously from the grinding surface 23a located on the rear side of the abrasive grain layer segment 23 in the bit rotation direction T, and is the foremost end of the convex curved surface 23b in the bit rotation direction T. The line 23c continues to the fixing surface 1a of the base metal 1 with the abrasive grain layer segment 23. The width of the abrasive grain layer segment 23 is larger than the thickness of the base metal 1, for example, as shown in FIG. Further, the abrasive grain layer segment 23 is a metal bond grindstone, in which superabrasive grains such as diamond and CBN are dispersed and arranged in a metal binding phase made of Ni or Cu alloy. However, other abrasives and binders may be used in the present invention. Here, the grinding surface 23a of the abrasive grain layer segment 23 is
Due to the presence of the convex curved surface 23a, the area to be ground in contact with the workpiece W is smaller than that of the conventional bit, so that the distance L provided between the respective abrasive grain layer segments 23 is reduced.
Is made smaller than the conventional bit, so that the same grinding area as the conventional bit is obtained.

Next, an example of a dry drilling method using the bit 30 will be described. In this method, first, a driving device connected to the shaft 2 of the bit 30 causes the bit 3 to be driven.
0 is rotated around the axis, and each abrasive grain layer segment 23 is pressed against the work material W to start cutting, and at the same time, free abrasive grains 4 a and air are introduced into the base metal 1 through the hollow shaft 2 of the bit 30. Supply.

As the free abrasive grains 4a, super abrasive grains or general abrasive grains such as SiC and Al ₂ O ₃ can be used.
Supplied with air in powder state. Loose abrasive 4
The average particle diameter of a is not necessarily limited, but is preferably about 100 to 30% of the average particle diameter of the abrasive grains in the abrasive grain layer segment 23 in order to enhance the dressing effect.

After the loose abrasive grains 4a and the air supplied into the base metal 1 reach the cutting region on the front end side, as shown in FIG. 3, the fixing surface 1a between the adjacent abrasive grain layer segments 23, 23 is formed. It flows out and rotates along with the convex curved surface 23b of the abrasive grain layer segment 23 by the rotation of the base metal 1, and enters the interface between the grinding surface 23a of the abrasive grain layer segment 23 and the workpiece W, The metal binding phase exposed on the grinding surface 23a is worn to promote the self-generated cutting action and maintain sharpness.
The loose abrasive grains 4a used for such dressing are sequentially discharged to the outside of the bit 30 together with air with cutting powder as the bit 30 rotates. Thereby, clogging of the grinding surface 23a of the abrasive layer segment 23 can be prevented, seizure of the grinding surface 23a can be suppressed, uneven wear can be prevented, the discharge of cutting powder can be promoted, and the life of the abrasive layer segment 23 can be extended. .

According to the bit and the drilling method configured as described above, the free abrasive grains 4 a and the air introduced when drilling the workpiece W are projected from the gaps between the respective abrasive grain layer segments 23. The grinding surface 2 is guided by the curved surface 23b.
3a is supplied to the interface between the work material W and sharpens the abrasive grain layer segment 23. The sharpness of the abrasive grain layer segment 23 is always maintained well, the discharge of cutting chips is enhanced, and heat is generated. Good and stable sharpness can be obtained over a long period of time by suppressing abrasion. Further, since the convex curved surface 23b of the abrasive grain layer segment 23 continues to the fixed surface 1a of the base metal 1 with the abrasive grain layer segment 23, the abrasive grain layer segment 23
Even when is worn, the convex curved surface 23b is always present on the front side in the rotation direction T continuously to the grinding surface 23a, and good and stable sharpness of the abrasive grain layer segment 23 can be obtained for a long period of time. Also, loose abrasive grains 4a are used as the grinding medium 4.
When the drilling of the work material W is performed in a dry manner using the air and the air, the free abrasive grains 4a sharpen the abrasive grain layer segments 23, always keep the sharpness good, and the effect of preventing clogging, This is particularly noticeable in comparison with conventional dry drilling.

Further, since the front side of the abrasive grain layer segment 23 in the bit rotation direction T is a convex curved surface 23b,
The difference in width between the width of the abrasive grain layer segment 23 and the thickness of the base metal 1 does not occur because the front side in the bit rotation direction T of the abrasive grain layer segment 23 is worn away due to the perforation of the work material W. Can be maintained, and the escape of the grinding medium and chips can be favorably maintained. In addition, by changing the shape of the convex curved surface 23b according to the type of the workpiece W, the state of the chips and the force applied to the cutting can be controlled.

In the present embodiment, the work material is drilled in a dry manner, but even when the work material is drilled in a wet manner using a grinding fluid such as water as a grinding medium, a convex shape is formed. The grinding fluid can be guided to the interface between the workpiece W and the grinding surface 23a by the curved surface 23b, and the same effect as in the case of the dry type can be obtained.

Next, a modification of the bit according to the present invention will be described. The bit 40 according to this modification has substantially the same configuration as the above-described embodiment, and is different from the above-described embodiment only in the arrangement of the abrasive grain layer segments 23. The bit 40 according to the present modification has a cylindrical base 1 and a cylindrical shaft portion 2 formed coaxially on the base end thereof, and a distal end of the base 1 as shown in FIG. A plurality of abrasive grain layer segments 23 having a substantially arc shape are arranged in a line in the circumferential direction of the base metal 1 without any gap and fixed by, for example, brazing or the like. When the bit 40 having such a configuration is used, even when the convex curved surface 23b is provided at the tip of the abrasive grain layer segment 23, the grinding area of the entire bit by the ground surface 23a is maintained at least equal to that without the convex curved surface 23b. The grinding and cutting efficiency is improved. Moreover, adjacent abrasive grain layer segments 2
An interval between the convex and concave surfaces 23b is formed between 3 and 23, so that heat generation during grinding and cutting can be suppressed, and discharge of chips can be promoted.

[0019]

According to the present invention, the following effects can be obtained. That is, according to the bit of the first aspect, the portion of the ground surface of the abrasive grain layer segment located on the front side in the bit rotation direction is a convex curved surface that approaches the base metal toward the front side in the rotation direction. By doing so, a part of the grinding medium introduced during the drilling of the work material is supplied to the interface between the grinding surface and the work material so as to be rolled into the convex curved surface, thereby sharpening the abrasive grain layer segments. By doing so, the sharpness is always kept stable and good, clogging can be prevented, and good chip discharge property can be obtained.

According to the bit according to the second aspect, in the bit according to the first aspect, the convex surface located on the front side in the bit rotation direction of the tip end surface of the abrasive layer segment has an abrasive layer of a base metal. By continuing to the fixed surface with the segment, the convex curved surface shape remains to the end when worn, so that the abrasive grain layer segment can maintain a stable and good sharpness for a long time, and also has good chip discharge property Is obtained.

According to the third aspect of the present invention, the bit is rotated around an axis by using the bit according to the first or second aspect, and each abrasive grain layer segment is cut into a work material. While introducing loose abrasive grains into the bit body,
By performing perforation processing of the work material while supplying the free abrasive grains between the ground surface of the abrasive grain layer segment and the work material, grinding such that the free abrasive grains are caught in the convex curved surface, It is supplied to the interface between the surface and the work material to sharpen the abrasive grain layer segment, keep the sharpness always good, prevent clogging, and obtain good chip discharge performance compared to the conventional It becomes particularly noticeable.

[Brief description of the drawings]

FIG. 1 is a perspective view of a tip portion showing a bit according to an embodiment of the present invention.

FIG. 2 is an enlarged side view of a main part showing a bit according to the embodiment of the present invention.

FIG. 3 is an enlarged front view of a main part showing a bit according to an embodiment of the present invention.

FIG. 4 is an enlarged side view of a main part showing a modification of the bit according to the embodiment of the present invention.

FIG. 5 is a side sectional view showing a general bit.

FIG. 6A is a perspective view of a tip portion showing a conventional bit, and FIG. 6B is an enlarged side view of a main part of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal 1a Fixed surface 2 Shaft part 23 Abrasive layer segment 23a Grinding surface 23b Convex curved surface 23c End line 30, 40 bits T Bit rotation direction

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tsuyoshi Kawahara 681 Saedocho, Tsuzuki-ku, Yokohama-shi, Kanagawa Prefecture Japan Diamond Co., Ltd. F-term (reference) 2D029 EA01 FA01 FB00 FC02 FD03 3C063 AA02 AB05 BA04 BA10 BB02 BB03 BB04 BC02 BG10 BH05 EE15 EE21 FF18 FF20 3C069 AA04 BA09 BB01 CA07 EA01

Claims (3)

[Claims] 1. A bit having a cylindrical base metal and a plurality of abrasive grain layer segments fixed along a tip of the base metal, wherein the bit is rotated around an axis of the base metal. A bit, characterized in that a portion of the ground surface of the layer segment located on the front side in the bit rotation direction has a convex curved surface that approaches the base metal as it goes forward in the rotation direction. 2. The bit according to claim 1, wherein the convex curved surface continues to a surface of the base metal fixed to the abrasive grain layer segment. 3. A drilling method using the bit according to claim 1 or 2, wherein the bit is rotated around an axis so that each abrasive grain layer segment is cut into a work material. A drilling method, wherein free abrasive grains are introduced into the main body, and the work material is processed while supplying the free abrasive grains between the ground surface of the abrasive grain layer segment and the work material.