JP2001096526A - Core bit for anchor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core bit which is a core bit for anchor for perforating a hole for anchor and wherein a core is hardly broken during perforation and when the core is broken, it is easily taken out from a tube. SOLUTION: In a core bit with a diameter of at most 50 mm for a portable perforation device, a thick-walled part 1a whose outer peripheral face is approximately the same face as the outer peripheral face of a chip 2 is provided on one end of the tube 1. Parts except one end of the tube are constituted of a thin-walled part 1b and the outer diameter of the thin-walled part 1b is smaller than the thick-walled part 1a and the inner diameter is the same diameter as the thick-walled part 1a. When the sum of the length in the axial direction of the core bit of the thick-walled part 1a and the chip 2 is h and the total length of the core bit is L and the outer diameter of the thick-walled part 1a is d, the thick-walled part a is formed so as to be 2L/ d<=h<=L/2d. In addition, a spiral channel 1c is provided on the thick-walled part 1a and this channel is formed by providing an angle of at least 45 degree to at most 85 degree to the axis of the tube 1. In addition, the inner peripheral face of the chip 2 is projected more to the inside in the radial direction than the inner peripheral face of the tube 1 and the step difference between the chip 1 and the tube 2 is at least 0.5 mm and at most 1.0 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core bit for drilling a work material such as concrete, and more particularly to an anchor core bit for drilling a hole for an anchor.

[0002]

2. Description of the Related Art Generally, when fixing air-conditioning-related devices and pipes in a building, holes are formed in a concrete wall surface. Conventionally, in order to make this hole, drilling work was generally performed using a hammer drill with a carbide tip at the tip.However, the method of drilling with a hammer drill generates noise and vibration. However, there is a problem that drilling work in an office building or the like cannot be performed unless it is a holiday.

In order to reduce the above noise and vibration, a core bit as shown in FIG. 3 has recently been used. This core bit is made by joining a sintered tip containing superabrasive grains such as diamond to the tip of the tube, and the method using this core bit does not generate vibration like a hammer drill, so noise is also reduced. It has the advantage of being smaller, making it possible to drill in office buildings during the daytime on weekdays.

[0004]

In a core bit generally used conventionally, a diameter of a hole to be drilled is 60 mm.
The diameter of the core bit used for the anchor as described above is small, and the diameter of the hole to be drilled is small, usually about 4 mm to 30 mm, and about 50 mm for a large one. Moreover, the depth of the hole to be drilled is about 150 mm to 200 mm for a 16 mm diameter, and 300 to 350 mm for a 30 mm diameter,
Compared to a commonly used core bit, the actual situation is that the drilling depth is deeper with respect to the diameter of the hole.

In a conventional core bit, a drilling device is fixed to a work material or the like for drilling. On the other hand, when the drill is used for an anchor as described above, the work is performed by attaching the core bit to a hand-held drilling device. Therefore, it is difficult to feed the core bit straight to the work material. Therefore, the core inside the tube is easily broken when the core bit is tilted with respect to the hole drilled during drilling, and if the core is frequently broken, it takes time to remove the broken core because the inner diameter of the tube is small. Occurs.

[0006] The core bit of the present invention is to solve the above problems. That is, the present invention provides a core bit in which the core is not easily broken when a punching operation is performed by a hand-held drilling device, and the core can be easily taken out from the inside of the tube.

[0007]

The core bit of the present invention comprises:
It has a diameter of 50 mm or less, and is used for a hand-held punch, and includes a tube, a tip, and a mounting portion. The tip is a sintered body of metal powder containing superabrasive grains bonded to one end of the tube, and the mounting portion is mounted on a punching device provided at the other end of the tube. At one end of the tube, the outer peripheral surface has a thick portion almost flush with the outer peripheral surface of the chip, and the portion other than the one end of the tube is a thin portion having a smaller outer diameter and the same inner diameter as the thick portion. When the sum of the lengths of the thick portion and the chip is h, the total length of the core bit is L, and the outer diameter of the thick portion is d, 2L / d ≦ h ≦ L / 2. A thick portion and a chip are formed on the substrate. However, the length here indicates the axial length of the core bit.

The above equation can be explained as follows. By providing a thick portion at one end of the tube, the outer peripheral surface of which is substantially flush with the outer peripheral surface of the chip, a force in a direction in which the core bit inclines as the entire core bit enters the work material as the drilling proceeds. Also, since the thick portion contacts the wall surface of the hole, the inclination of the core bit is suppressed.

The effect of suppressing the inclination of the core bit increases as the length of the thick portion increases. However, since the outer diameter of the outer peripheral surface of the chip and the outer diameter of the thick portion are substantially the same, the thick portion and the work material come into contact with each other, and the rotational resistance increases. Moreover, in the case of the anchor core bit, since a hand-held drilling device is used as described above, the device needs to be made as small as possible, and the output of the motor is inevitably reduced.

Here, when focusing on the inclination of the core bit during the drilling operation, when the core bit has the same overall length, the core bit is more likely to be inclined as the diameter of the core bit is smaller. When proceeding with the test taking this relationship into consideration, the sum of the thickness of the thick portion and the length of the chip is at least twice as large as the total length of the core bit divided by the diameter of the circumference formed by the outer peripheral surface of the chip. For example, they found that the inclination of the core bit was small and the core inside the tube was hard to break. In the present invention, since the outer peripheral surface of the chip and the outer peripheral surface of the thick portion are substantially flush, the diameter of the circumference formed by the outer peripheral surface of the chip is the same as the diameter of the thick portion, and the above relational expression is obtained. .

As for the upper limit of the sum of the axial lengths of the thick portion and the chip, there is a problem with the output of the motor as described above. Even if the upper limit is too long, the effect of suppressing the inclination of the core bit does not improve. For this reason, it is desirable that the total length of the core bit is not more than １ ／.

In the above-mentioned core bit, preferably, a spiral groove is provided in the thick portion. By providing the spiral groove, it is possible to reduce the resistance of contact between the thick portion and the wall surface of the hole and to smoothly discharge chips.

[0013] The above-mentioned helical groove is formed with respect to the axis of the tube.
More preferably, it is formed at an angle of 45 degrees or more and 85 degrees or less. This angle is necessary for smooth chip discharge, and considering the reduction of the contact resistance between the thick part and the wall surface of the drilled hole, it is necessary to increase the angle as the core bit diameter increases. desirable.

Further, the inner peripheral surface of the tip projects radially inward from the inner peripheral surface of the tube, and the step between the tip and the tube is 0.5 mm or more and 1.0 mm or less. If it is less than 0.5 mm, it is not easy to take out the core remaining inside the tube, and if it exceeds 1.0 mm, the effect of easily taking out the core is not improved. Since only the resistance increases, the effect is reversed. When taking out the core is considered, it is more preferable that the thickness be 0.7 mm or more and 1.0 mm or less.

[0015]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a front view schematically showing a configuration of a core bit according to an embodiment of the present invention, and FIG.
And FIG. 3 is a front view schematically showing a configuration of a conventional core bit.

Referring to FIGS. 1 and 2, the core bit of the present embodiment has an outer diameter of 50 mm or less, and a tip 2 containing superabrasive grains is joined to the tip of a cylindrical tube 1 by brazing or the like. At one end of the tube 1, a thick portion 1a whose outer peripheral surface is substantially flush with the outer peripheral surface of the chip 2 is provided.

The sum of the lengths of the thick portion 1a and the chip 2 is h,
When the total length of the core bit is L and the outer diameter of the thick portion is d, h is determined so that 2L / d ≦ h ≦ L / 2. The length here indicates the axial length of the core bit. A spiral groove 1c having an angle of 45 degrees or more and 85 degrees or less with respect to the axis of the tube 1 is formed on the outer peripheral surface of the thick portion 1a.
Is provided.

A portion other than one end of the tube 1 is a thin portion 1b.
And a step is provided on the outer peripheral surface of the boundary between the thick portion 1a and the thin portion 1b. The inner diameters of the thick part 1a and the thin part 1b are the same, and the inner peripheral surfaces of both parts are flush. At the other end of the tube 1, an attachment portion 3 for attaching a core bit to a drilling device is joined by welding or the like. The mounting portion 3 may be cut out of the same material as the tube 1 and may be formed integrally.

The inner peripheral surface of the tip 2 projects radially inward from the inner peripheral surface of the tube 1, and a distance of 0.5 m
A step of not less than m and not more than 1.0 mm is provided. If the step is small, it becomes difficult for the core to come off from the inside of the tube 1. Further, in order to increase the step, it is necessary to increase the thickness of the chip 2 in the radial direction. If the chip 2 is thicker, the resistance at the time of perforation is increased.

[0021]

Next, embodiments of the present invention will be described in detail.

(Example 1) Outer diameter 17.0 mm, inner diameter 1
A pipe material having a length of 3.0 mm and a length of 150 mm is joined to a pre-machined mounting portion 3 for a drilling device by welding.
The diameter of the thin portion 1b of the tube 1 is 15.0 based on
mm, the diameter of the thick portion 1a at one end of the tube 1 is 16.0.
mm. The length of the thick portion 1a in the core bit axial direction was 40 mm, and a spiral groove 1c having an angle of 76 degrees with respect to the axis of the tube 1 was formed in the thick portion 1a. This groove has a width of 4.0 mm and a depth of 0.5 mm. A tip 2 obtained by mixing diamond and Co powder of particle size # 40 and forming and sintering was joined to the end face of one end of the tube 1 by brazing. The diameter of the circumference formed on the outer peripheral surface of the tip 2 is the same as that of the thick portion 1a of the tube 1.
6.0 mm, the diameter of the circumference formed by the inner peripheral surface is 11.4
mm, and the length in the core bit axial direction is 8.0 mm.

The above-described core bit was attached to a hand-held punch, and a punch test was performed. The number of rotations of the core bit is set to 5310 rpm, and the work material has a pressure resistance of 255.
Perforation was repeated 50 times at a perforation depth of 100 mm using unreinforced concrete of kgf / cm ² . As a result, the average drilling speed was 420 mm / min, the number of times the core was broken during drilling one hole was 3 to 5 times, and the length of the broken core was 20 mm to 55 mm, which was easier than the inside of the tube. I was able to take it out. The time required for perforation per hole including the time for taking out the core from the inside of the tube due to the broken core was 60 seconds to 90 seconds.

(Comparative Example 1) The diameter of each part of the tube 1 of the core bit of Example 1 was reduced by 0.4 mm, the length of the thick portion 1a in the core bit axial direction was 5 mm, and the spiral groove 1c was formed. A drilling test was performed using a core bit not provided as a comparative example. The length of the thick portion 1a in the core bit axial direction,
The specifications and drilling test conditions were the same as in Example 1, except that a step was provided on the outer peripheral surface of the chip 2 and the thick portion 1a to reduce the step on the inner peripheral surface. As a result, the average drilling speed was almost equal at 410 mm / min, but the number of times the core was broken during drilling one hole was 10 to 18 times, and the length of the broken core was 5 mm to 15 mm. It took a lot of time to remove the core from inside the tube.
The time required for perforation per hole, including the time for removing the core from the inside of the tube due to the broken core, is 130 minutes.
Seconds to 210 seconds. This was mainly due to the fact that the broken core was short and the core became oblique inside the tube and was caught by the chip 2.

(Example 2) Outer diameter 33.0 mm, inner diameter 2
A pipe material having a length of 9.0 mm and a length of 350 mm is joined to a pre-machined mounting portion 3 for a drilling device by welding.
The diameter of the thin portion 1b of the tube 1 is 31.0
mm, the diameter of the thick portion 1a at one end of the tube 1 is 32.0 mm.
mm. The length of the thick portion 1a in the core bit axial direction was 30 mm, and a spiral groove 1c having an angle of 83 degrees with respect to the axis of the tube 1 was formed in the thick portion 1a. This groove has a width of 4.0 mm and a depth of 0.5 mm. A tip 2 obtained by mixing diamond and Co powder of particle size # 40 and forming and sintering was joined to the end face of one end of the tube 1 by brazing. The diameter of the circumference formed on the outer peripheral surface of the tip 2 is the same as that of the thick portion 1a of the tube 1.
2.0 mm, the diameter of the circumference formed by the inner peripheral surface is 27.4
mm, and the length in the core bit axial direction is 8.0 mm.

Using the above-mentioned core bit, a piercing test was performed in the same manner as in Example 1. The drilling depth of this core bit was 300 mm, and drilling was repeated 50 times. As a result, the average drilling speed was 270 mm / min, the number of times the core was broken during drilling one hole was 3 to 5 times, and the length of the broken core was 45 mm to 120 mm, which was easier than the inside of the tube. I was able to take it out. 1 including the time to remove the core from the inside of the tube because the core was broken
The time required for drilling per hole was from 60 seconds to 90 seconds.

[0027]

As can be seen from the above description, in the core bit of the present invention, the outer peripheral surface of the thick portion at one end of the tube is made substantially flush with the outer peripheral surface of the chip so as to easily contact the wall surface of the drilled hole. Because the length of the thick portion is increased, when drilling with a hand-held drilling device, the core bit is less likely to tilt with respect to the drilled hole and the core is less likely to break. Further, since the core is not easily broken, the length of the core is increased even if the core is broken, so that the core can be easily taken out from the inside of the tube. Further, by providing a spiral groove in the thick portion, side resistance can be reduced, and chip discharge can be performed smoothly. From the above effects, a core bit for anchor with good sharpness and work efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view of a core bit according to the present invention.

FIG. 2 is an enlarged sectional view of a thick portion of a core bit according to the present invention.

FIG. 3 is a front view of a conventional core bit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 1a Thick part 1b Thin part 1c Spiral groove 2 Chip 3 Mounting part

Claims (4)

[Claims] 1. A tube 1; a tip 2 including superabrasive grains joined to one end of the tube 1; and an attachment portion 3 attached to the other end of the tube 1 for attaching to a punching device. At one end of the tube 1, an outer peripheral surface has a thick portion 1a substantially flush with the outer peripheral surface of the chip 2, and portions other than one end of the tube 1 have a smaller outer diameter than the thick portion 1a. The inner diameter is composed of the thin portion 1b having the same diameter, the sum of the lengths of the thick portion 1a and the chip 2 is h, the total length of the core bit is L, and the outer diameter of the thick portion 1a is d. A core bit having a diameter of 50 mm or less for a hand-held drilling device, wherein 2L / d ≦ h ≦ L / 2. 2. The core bit according to claim 1, wherein the thick portion 1a is provided with a spiral groove 1c. 3. The core bit according to claim 2, wherein the spiral groove 1c is formed at an angle of not less than 45 degrees and not more than 85 degrees with respect to the axis of the tube 1. 4. The inner peripheral surface of the chip 2 is the tube 1
And a step between the inner peripheral surface and the inner peripheral surface thereof is in a range of 0.5 mm or more and 1.0 mm or less.
Or the core bit of 3.