JPH03279589A - Button bit - Google Patents

Abstract

PURPOSE:To improve the boring speed by making the diameter of the installing part of an edge positioning at the outermost circumference of a bit head as D, the projecting amount from the bit head in the diameter direction as S, and setting the relation of D and S within a specific value. CONSTITUTION:Each of plural edges 20 implanted at the top surface of the head 20 of a bit main body is formed in a columnar form, and composed of an installing part 21 laid in the top surface, and boring part 22 formed on the top surface of the installing part 21. Then, in the edges 20 positioning at the outermost position of the head 12, of the plural edges 20, a part of each boring part 22 is projected in the diameter direction from the head 12. And when the diameter of the installing part 21 is made D, and the projecting amount is made S, S is set as S=0.2 to 0.6D. As a result, almost no cutting is accumulated in the clearance between the head and the hole wall being exhausted effectively, and the boring speed can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a button bit in which a plurality of blades are provided on the bit head, and particularly to a button bit that can improve drilling speed.

"Prior Art" For example, a button bit shown in FIG. 6 is known as an example of a button bit used for excavating mud, sand, soft rock, etc.

The button bit shown in this figure has a plurality of blade bodies 2 embedded in the tip surface of the bit head l.

The blade 2 has a hemispherical perforation part 2b formed at the tip of a cylindrical mounting part 2a embedded in the bit head l, and is located at the outermost periphery of the bit head l. A portion of the perforation portion 2b of the blade body 2 projects radially from the bit head l. Then, this protrusion amount S is
Assuming that the diameter of is D, it is generally set to S<0.18D.

``Problems to be Solved by the Invention'' By the way, when drilling is performed using the button bit as described above, most of the machining powder is discharged backward through the machining powder (not shown) formed on the bit head l. However, there was a problem in that part of the powder remained in the small gap between the bit head l and the hole wall, reducing the drilling speed.

``Object of the Invention'' The present invention has been made in view of the above circumstances, and an object thereof is to provide a button bit that can improve the drilling speed.

"Means for Solving the Problem" In order to achieve the above object, the button bit of the present invention has a diameter D of the attachment part of the blade located at the outermost periphery of the bit head, and the tip of this attachment part. The amount of protrusion S in the radial direction of the perforated part formed in the bit head from the bit head is set to S=0.2D to 0.6D.

"Function" In the button bit of the present invention, the amount of protrusion S in the radial direction of the punching part from the bit head is S = 0.2 D ~
Since it is set to 0.6D, the gap between the bit head and the hole wall is larger than the conventional one, and the cutting powder hardly stays in this gap and is efficiently discharged, improving the drilling speed.

Furthermore, the reason why the protrusion amount S is limited as described above is because S<0.
With 2D, the gap between the bit head and the hole wall is not so large compared to the conventional one, so the above effect cannot be obtained.On the other hand, with S〉0゜6D, the amount of protrusion of the drilling part is large. This is because the blade body cannot be stopped by the force received from the hole wall, and the drilling portion may be chipped or the blade body itself may be pulled out from the bit head.

"Embodiment" Hereinafter, an embodiment of the button bit of the present invention will be described with reference to FIGS. 1 to 5.

In these figures, reference numeral 10 indicates the bit body. This bit body IO is made of steel, has a substantially hemispherical tip surface 11, and has a head 12 for drilling into rock, etc.
The mounting portion 13 has a smaller diameter and can be attached to a rock drill or the like.

There are three types of hollow grooves 14 and 15 on the outer periphery of the head 12.
．． [6... are formed at predetermined intervals in the circumferential direction. These hollowing grooves 14, 15, 16... are formed to extend from the distal end surface of the head 12 to the attachment part 13, respectively, and the hollowing powder is passed through these hollowing grooves 14, 15, 16... Most of it is ejected backwards. Further, a pair of jet ports 17.17 for jetting out compressed air are formed on the distal end surface 11 of the head 12.
17 is a center hole 18 formed in the center of the bit body lO
is communicated with. Most of the flour is sent into the flour grooves 14, 15, 16, .

Further, a plurality of blade bodies 20 are provided on the distal end surface 11 of the head 12.
... has been planted. This blade body 20 has a cylindrical shape and includes a mounting portion 21 embedded in the tip surface 11, and a mounting portion 21 embedded in the tip surface 11.
It is composed of a perforated portion 22 formed at the tip of the holder. As shown in FIG. 4, the perforated portion 22 is shaped like a bullet, and the outer peripheral edge of the tip of the cross section taken along a plane passing through its axis is formed by two types of curves T1 and T.

That is, the curves T , , T , are circular arcs of radius R, , R, centered at point 01°01 on the line segment, the curve T2 is a circular arc centered at point 02, and the curves T , , T , One end of each other and both ends of the curve T are smoothly connected. The radius R3 is set to R = 0.85D-1.15D, where D is the diameter of the mounting portion 13, and the radius R9 is set to R2 = 0.2D to 0.35D.

As shown in FIG. Although it is provided so as to protrude in the radial direction, the amount of protrusion S is S=0.2D to 0.
．． It is set to 6D.

By setting the amount of protrusion of the perforation part 22 of the blade body 20 in this way, the gap between the head 12 and the hole wall 3 becomes larger than before, so that the turning powder hardly stays in this gap. It is efficiently discharged, and therefore the drilling speed is improved compared to the conventional method.

Here, the reason why the protrusion amount S is limited as above is that S<0
．． In 2D, the gap between the head IO and the hole wall is not so large compared to the conventional one, so the above effect cannot be obtained. On the other hand, when S>0.6D, the protrusion amount of the perforation part 22 is large. This is because the blade body 20 may not be able to withstand the force received from the hole wall, and the perforated portion 22 may be chipped, or the blade body 22 itself may be pulled out from the head 22.

In addition, since the shape of the perforated part 22 of the blade body 20 is shaped like a bullet as described above, the wall thickness on the side surface is thicker than the conventional spike-shaped perforated part (indicated by the two-dot chain line in Fig. 4). As a result, wear resistance and toughness are improved.

"Effects of the Invention" As explained above, according to the button bit of the present invention, the diameter of the attachment part of the blade located at the outermost periphery of the bit head is D, and the diameter of the attachment part of the blade body located at the outermost periphery of the bit head is The amount of radial protrusion S of the drilling part from the bit head is set to S = 0.2D to 0.6D, so the gap between the bit head and the hole wall is larger than before. Since the powder remaining in this gap is discharged very efficiently, the drilling speed can be improved compared to the conventional method.

[Brief explanation of drawings]

1 to 5 show an embodiment of the button hit of the present invention. FIG. 1 is a front view, FIG. 2 is a fixed view taken along the line ■-■ in FIG. 1, and FIG. 3 is a sectional view. , FIG. 4 is an enlarged sectional view of the blade body, and FIG. 5 is a sectional view of the main part showing the drilling state.
FIG. 6 is a sectional view showing an example of a conventional button bit. 12...head, 20...blade body, 21.
...Mounting part, 22...Drilling part.

Claims (1)

[Scope of Claims] A plurality of blade bodies each having a cylindrical attachment part with a perforation formed at the tip thereof are provided in the bit head by embedding the attachment parts, and In a button bit, the blade body located at the outermost periphery of the bit head is provided with a part of its perforation part protruding from the bit head in the radial direction, and the blade body is located at the outermost periphery of the bit head. The diameter of the attachment part of the blade body is set as D, and the amount of protrusion S in the radial direction of the drilling part formed at the tip of this attachment part from the bit head is set to S = 0.2D to 0.6D. A button bit characterized by: