JP2012127062A - Drilling bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling bit capable of efficiently discharging cuttings around a central axis in the tip surface of a bit body so as to increase drilling speed.SOLUTION: A drilling bit 10 is provided with a cylindrical bit body 1 which is rotated around a central axis O, a plurality of drilling chips 3 protrusively formed on a tip surface 2 of the bit body 1 and a discharge groove 4 which is recessed from the tip surface 2 of the bit body 1 and which is formed so as to be extended in the radial direction. At least one portion of the discharge groove 4 is arranged in a rotational locus Caround the central axis O of an innermost peripheral chip 31A disposed closest to the central axis O of the bit body 1, among the drilling chips 3.

Description

  The present invention relates to a drill bit that is attached to a rock drill or the like and is used for excavating the ground or rock.

  As this type of excavation bit, for example, as shown in Patent Document 1 below, a bit body that is formed in a columnar shape and rotated around a central axis, and a plurality of excavation tips that protrude from the front end surface of the bit body And a discharge groove that is recessed from the tip end surface of the bit body and that extends in the radial direction is known. Further, the discharge groove of the excavation bit extends from the substantially radial center between the central axis and the outer peripheral surface of the bit body toward the radially outer side, and the flour that has been excavated by the excavation tip passes through the discharge groove. It passes through the outer peripheral surface side.

Japanese Patent No. 3190287

  However, in the conventional excavation bit, the flour around the central axis on the tip surface of the bit body cannot be discharged efficiently.

  The present invention has been made in view of such circumstances, and provides a drilling bit that can efficiently discharge the dust around the central axis of the tip surface of the bit body and increase the drilling speed. The purpose is that.

In order to achieve the above object, the present invention proposes the following means.
That is, the present invention comprises a bit body that is formed in a columnar shape and is rotated around a central axis, a plurality of excavation tips that protrude from the front end surface of the bit main body, and are recessed from the front end surface of the bit main body in the radial direction. An excavation bit formed to extend, and of the excavation tip, the innermost tip disposed closest to the central axis of the bit body around the central axis At least a part of the discharge groove is arranged in the rotation locus.

  According to the excavation bit according to the present invention, a plurality of excavation tips project from the front end surface of the bit body, and the excavation bit crushing efficiency is secured by these excavation tips. Among these excavation tips, at least a part of the discharge groove is arranged in a rotation locus around the central axis of the innermost tip arranged closest to the central axis of the bit body.

Therefore, when the bit body is rotated around the central axis, the flour produced by excavation of the innermost tip is collected in the discharge groove portion located in the rotation locus of the innermost tip. And is discharged to the outer peripheral surface side through the discharge groove.
In this way, the discharge performance of the dusting at the center portion in the radial direction on the tip surface of the bit body is sufficiently ensured, so that the drilling speed of the excavation bit is increased.

  Moreover, the excavation bit which concerns on this invention WHEREIN: The said discharge groove is good also as forming so that the outer peripheral surfaces which pinch | interpose the central axis of the said bit main body may be connected.

  In this case, since the discharge groove is formed so as to connect the outer peripheral surfaces sandwiching the central axis of the bit body, the flour that has been collected at the central portion in the radial direction of the discharge groove is disposed radially in the discharge groove. It flows in the direction which tends to flow, and is discharged to the outer peripheral surface side. That is, since there is a degree of freedom in the discharge direction of the flour that has been collected in the discharge groove, the dust discharge performance is further enhanced.

  In the excavation bit according to the present invention, the discharge groove may be formed in a Z shape or an S shape when the bit body is viewed from the front end surface side.

  In this case, the discharge groove gradually extends toward one of the circumferential directions around the central axis of the bit body as it goes from the radially central portion toward the outer peripheral surface. A sufficient amount of powder is secured. Thereby, the discharge property of flouring improves.

  According to the excavation bit according to the present invention, it is possible to efficiently discharge the flour around the central axis of the tip surface of the bit body, and to increase the drilling speed.

It is a perspective view which shows the excavation bit which concerns on one Embodiment of this invention. It is a side view which shows the excavation bit which concerns on one Embodiment of this invention. It is a front view which shows the excavation bit which concerns on one Embodiment of this invention. It is a sectional side view which shows the excavation bit which concerns on one Embodiment of this invention, and shows the AA 'cross section of FIG. 3 with a continuous line, and shows a BB' cross section with a dashed-two dotted line.

Hereinafter, an excavation bit according to an embodiment of the present invention will be described with reference to the drawings.
The excavation bit 10 according to the present embodiment is attached to a rock drill or the like and used for excavation of the ground or rock.
As shown in FIG. 1 to FIG. 4, the excavation bit 10 has a cylindrical shape and is rotated around a central axis O, and a plurality of excavation tips protruding from the distal end surface 2 of the bit main body 1. 3 and a discharge groove 4 that is recessed from the distal end surface 2 of the bit body 1 and that extends in the radial direction.

  The bit body 1 is formed of a steel material or the like, and its outer shape has a cylindrical shape with the central axis O as the center. In FIG. 2, the bit body 1 includes a small diameter portion 1A having a constant outer diameter from the rear end portion (left side portion in FIG. 2) along the central axis O direction toward the front end portion (right side portion in FIG. 2). The intermediate diameter portion 1B located on the distal end side of the small diameter portion 1A and including a central axis O has a concave curve shape, and the outer diameter gradually increases toward the distal end side. And a tapered large-diameter portion 1C whose outer diameter gradually increases toward the side. The distal end edge of the large diameter portion 1C is formed so as to intersect the distal end surface 2 of the bit body 1, and the bit body 1 has a maximum outer diameter at the position of the intersecting ridge line between the large diameter portion 1C and the distal end surface 2. It has become.

  1 and 3, the front end surface 2 of the bit body 1 has a flat surface 2A that is substantially circular with the central axis O as the center and is perpendicular to the central axis O, and radially outward of the flat surface 2A. And a gauge surface 2B that is positioned and surrounds the entire circumference of the flat surface 2A. As shown in FIG. 2, the gauge surface 2B is formed so as to be gradually inclined toward the rear end side from the radially inner side to the outer side, and the outer edge portion intersects the tip edge of the large diameter portion 1C. is doing.

  In addition, a plurality of outer peripheral grooves 6 are formed on the outer peripheral surface of the bit body 1 while extending in the direction of the central axis O and spaced in the circumferential direction. As shown in the front view of FIG. 3, the outer circumferential groove 6 has the deepest groove depth among the outer circumferential grooves 6, and a pair of groove wall portions facing the circumferential direction gradually move toward each other inward in the radial direction. The first outer peripheral groove 6A, which is an inclined surface to be approached and has a bottom surface portion connecting the groove wall portions formed in a concave cross-sectional shape and positioned at the outer edge of the flat surface 2A in the radial direction, and these outer peripheral grooves 6 The groove depth is the shallowest, and is formed in a triangular cross-section, and the bottom surface portion thereof is located in the radial center of the gauge surface 2B, and the groove depth is the first and second groove depths. A third outer peripheral groove 6C formed between the outer peripheral grooves 6A and 6B and having a circular arc cross section is included.

  Among these outer peripheral grooves 6, a pair of first outer peripheral grooves 6 </ b> A are formed on the outer peripheral surface of the bit body 1 with the central axis O interposed therebetween. A pair of third outer peripheral grooves 6 </ b> C are formed on both sides of the central axis O so as to be positioned on the outer peripheral surface of the bit body 1 in the middle in the circumferential direction between the first outer peripheral grooves 6 </ b> A. In addition, the second outer peripheral groove 6B is formed in two pairs with the central axis O interposed therebetween so as to be positioned in the middle in the circumferential direction between the first outer peripheral groove 6A and the third outer peripheral groove 6C on the outer peripheral surface of the bit body 1. Yes.

  As shown in FIG. 4, the first outer circumferential groove 6A is opened from the front end surface 2 of the bit body 1 and is formed from the large diameter portion 1C to the rear end portion of the medium diameter portion 1B. It is set to gradually become shallower toward the rear end side. Further, the third outer peripheral groove 6C is opened from the front end surface 2 and is formed from the large diameter portion 1C to the rear end portion of the medium diameter portion 1B, and the groove depth is constant parallel to the central axis O. ing. The second outer circumferential groove 6B is open from the distal end surface 2 and is formed from the large diameter portion 1C to the distal end portion of the medium diameter portion 1B. The depth of the groove is constant parallel to the central axis O. Yes.

  In addition, in the small diameter portion 1 </ b> A of the bit body 1, a female screw hole 5 that opens to the rear end surface of the bit body 1 and extends toward the front end side is formed coaxially with the central axis O. The hole bottom (back surface) of the female screw hole 5 is located near the boundary between the small diameter portion 1A and the medium diameter portion 1B. A rod (not shown) such as a rock drill is screwed into and connected to the female screw hole 5. Then, by transmitting the rotational force around the central axis O and the thrust and striking force toward the distal end side of the central axis O from the rod to the bit body 1, the ground and the rock are excavated to form a hole. It has become so.

  Further, from the bottom of the female screw hole 5, a discharge hole 5A is formed along the central axis O toward the front end side to the boundary between the medium diameter portion 1B and the large diameter portion 1C. A plurality of blow holes 5B are branched from 5A so as to incline radially outwardly toward the front end side, and are opened in discharge grooves 4 described later. Then, a fluid such as air supplied through the rod is discharged from the discharge port 5A to the front end surface 2 through the blow hole 5B, and the dust produced by excavation is discharged to the rear side of the hole.

  In FIG. 3, a plurality of cylindrical excavation tips 3 made of a hard material such as cemented carbide are respectively implanted on the flat surface 2 </ b> A and the gauge surface 2 </ b> B of the distal end surface 2. The tip portions of these excavation tips 3 protrude from the tip surface 2 of the bit body 1 toward the tip side, and the portion exposed from the tip surface 2 is hemispherical. The excavation tip 3 of this embodiment is a so-called button tip.

  Of these excavation tips 3, the excavation tip 3 implanted in the flat surface 2A is a face tip 31, and the excavation tip 3 implanted in the gauge surface 2B is a gauge tip 32. In this embodiment, the face chip 31 and the gauge chip 32 have the same shape.

  A plurality of face chips 31 are arranged in the flat surface 2 </ b> A other than the discharge grooves 4 to be described later with a space between each other. Of these face chips 31, the face chips 31 are arranged closest to the central axis O. Is the innermost peripheral chip 31A.

Here, reference numerals C ₁ and C ₀ indicated by a two-dot chain line in FIG. 3 indicate rotation trajectories when the innermost peripheral tip 31A is rotated around the central axis O (of the outer peripheral surface of the innermost peripheral tip 31A, The rotation trajectory at the portion farthest from the central axis O is C ₁ (outer diameter of the rotation trajectory), and the rotation trajectory at the portion closest to the central axis O is C ₀ (inner diameter of the rotation trajectory). The diameter (outer diameter) d ₁ of the rotation locus C ₁ is set within a range of 0.3D to 0.5D with respect to the outer diameter D of the large diameter portion 1C of the bit body 1. Further, the diameter (inner diameter) d ₀ of the rotation locus C ₀ is set within the range of 0.05D to 0.15D with respect to the outer diameter D.
Moreover, the gauge chip | tip 32 is each arrange | positioned between the outer peripheral grooves 6 adjacent in the circumferential direction in the gauge surface 2B.

  Further, as shown in FIG. 3, when the bit body 1 is viewed from the distal end surface 2 side, the discharge groove 4 has a Z shape and connects the outer peripheral surfaces sandwiching the central axis O of the bit body 1. It is formed as follows. Specifically, the discharge groove 4 has a radially inward (center) central portion 4A located on the central axis O and in the direction between the axis of the innermost peripheral tip 31A and the central axis O. On the other hand, it crosses and extends so as to be substantially orthogonal.

  Further, the pair of outer portions 4B extending radially outward so as to bend from both ends of the central portion 4A of the discharge groove 4 are gradually opposite to the rotational direction T of the bit body 1 as it goes radially outward (see FIG. 3 extends in the counterclockwise direction around the central axis O. Further, the radially outer edge portion of the outer portion 4 </ b> B of the discharge groove 4 is continuous with the first outer peripheral groove 6 </ b> A on the outer peripheral surface of the bit body 1.

  Further, the discharge groove 4 is not formed rotationally symmetrically with respect to the central axis O, and the pair of outer portions 4B are set to have different lengths. Further, the center of the central portion 4A (the center in the length direction and the width direction) is offset from the central axis O.

In addition, at least a part of the discharge groove 4 is disposed in the rotation trajectories C ₁ and C _{0 of} the innermost peripheral tip 31A. In the present embodiment, the central portion 4A of the discharge groove 4 is disposed in the rotational path C _1, are radially inner portions of the pair of outer portions 4B of the discharge groove 4 is also disposed within the rotational locus C ₁ Yes. Also, part of the central portion 4A of the discharge groove 4, and a portion of the radially inner portion of the long one of the outer portion 4B of the total length of the pair of outer portion 4B is disposed in the rotation locus C ₀ Yes.

  Further, the discharge groove 4 has a concave curve in a cross section perpendicular to the extending direction. As shown in FIG. 4, the groove bottom of the discharge groove 4 is formed so as to be gradually inclined toward the rear end side from the radially inner side to the outer side. The cross section along the line is a convex curve, and is smoothly connected to the leading edge of the groove bottom of the first outer circumferential groove 6A.

Further, as shown in FIG. 3, the blow hole 5 </ b> B is opened so as to be positioned on the outer periphery of the rotation locus C <b> ₁ in the discharge groove 4.
In the present embodiment, the excavation tip 3 is not disposed in the discharge groove 4 and the outer peripheral groove 6, and all the excavation tips 3 protrude from the distal end surface 2 toward the distal end side.

As described above, according to the excavation bit 10 according to the present embodiment, a plurality of excavation tips 3 are disposed so as to protrude from the distal end surface 2 of the bit body 1 to the distal end side. A crushing efficiency of 10 is sufficiently secured. Among these excavation tips 3, at least a part of the discharge groove 4 is included in the rotation locus C ₁ around the central axis O of the innermost peripheral tip 31 </ b> A arranged closest to the central axis O of the bit body 1. Is arranged.

Therefore, when the bit body 1 is rotated about axis O, powder repeatedly to the innermost tip 31A has occurred by drilling discharge groove 4 portion located within the rotational locus C ₁ of outermost inner chip 31A It is collected in (the radially inner portions of the central portion 4A and the pair of outer portions 4B), passes through the discharge groove 4, and is discharged to the outer peripheral surface side of the bit body 1.
As described above, since the dischargeability of the dusting at the central portion in the radial direction (in the vicinity of the central axis O) in the distal end surface 2 of the bit body 1 is sufficiently ensured, the drilling speed of the excavation bit 10 is increased.

Furthermore, in the present embodiment, even in the rotation locus C ₀ of the center axis O of the innermost chip 31A, at least a portion of the discharge groove 4 is disposed. Thus, the innermost tip 31A is out of the counterbore powder produced by drilling, powder repeatedly flows through the central axis O side outermost inner peripheral chip 31A is, discharge groove 4 parts (center located within the rotational locus C ₀ Part of part 4A and part of the radially inner part of one outer part 4B) are collected, and the dischargeability of flouring is reliably improved.

  In addition, since the discharge groove 4 is formed so as to connect the outer peripheral surfaces sandwiching the central axis O of the bit body 1, the dust that has been collected at the central portion in the radial direction of the discharge groove 4 is discharged from the discharge groove 4. The inside flows to the outer portion 4B in the direction in which it easily flows in the radial direction, and is discharged to the outer peripheral surface side. That is, since there is a degree of freedom in the discharge direction of the flour that has been collected in the discharge groove 4, the discharge performance of the flour is further enhanced.

  Further, when the bit body 1 is viewed from the front end surface 2 side, the discharge groove 4 is formed in a Z shape, and the discharge groove 4 gradually rotates in the rotational direction of the bit body 1 from the radial center to the outer peripheral surface side. Since it extends toward the opposite side of T, the entire length of the discharge groove 4 is increased, and a sufficient amount of dusting is ensured. Further, as the bit body 1 rotates in the rotation direction T, the dust in the discharge groove 4 is easily guided toward the outer peripheral surface side of the bit body 1 by frictional resistance with the drilling surface. . Thereby, the discharge property of flouring improves.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the discharge groove 4 is formed in a Z shape when the bit body 1 is viewed from the front end surface 2 side. However, the present invention is not limited to this. It may be formed in a letter shape. In this case, since the discharge groove 4 gradually extends in the rotation direction T of the bit body 1 from the radial center to the outer peripheral surface side, the entire length of the discharge groove 4 becomes longer, and the amount of collected dust is reduced. Sufficiently secured.
Further, the shape of the discharge groove 4 is not limited to the above-described Z shape or S shape.

  In the above-described embodiment, the central portion 4A of the discharge groove 4 is located on the central axis O. However, the central portion 4A does not have to pass on the central axis O.

Further, in the above-described embodiment, at least a part of the discharge groove 4 is disposed in the rotation trajectories C ₁ and C ₀ of the innermost peripheral tip 31A. However, the present invention is not limited to this. Specifically, in the rotational locus C ₁ of the innermost chip 31A, may be disposed at least a portion of the discharge groove 4, the discharge groove 4 is may not be arranged in a rotation locus C _0. However, as described above, it is preferable that at least a part of the discharge groove 4 is arranged also in the rotation locus C ₀ , so that the discharge performance of the dusting is reliably improved.
Further, the innermost peripheral tip 31A may be arranged on the central axis O while the axis thereof is slightly deviated from the central axis O. In this case, at least a portion of the discharge groove 4 is disposed in the rotational path C _1.

Moreover, although the discharge groove 4 was formed so that the outer peripheral surfaces which pinch | interpose the center axis | shaft O of the bit main body 1 were formed, it is not limited to this. That is, the discharge groove 4, since at least a part may be disposed in a rotational locus C _1, for example, does not have a central portion 4A, it is composed of a pair of outer portions 4B away from each other It is also possible to do. Further, the discharge groove 4 may be formed of only one of these outer portions 4B. Alternatively, the discharge groove 4 may be composed of the central portion 4A and one of the pair of outer portions 4B.

  In the above-described embodiment, the excavation tip 3 is made of a button tip. However, the present invention is not limited to this, and may be, for example, another spike tip or a shell tip.

DESCRIPTION OF SYMBOLS 1 Bit main body 2 Front end surface 3 Excavation tip 4 Discharge groove 10 Excavation bit 31A Innermost peripheral tip C ₁ Rotation locus (the outer diameter of the rotation locus) around the central axis of the innermost periphery tip
C ₀ of the innermost chip center axis of the rotation locus (inner diameter of rotational path)
O Center axis

Claims (3)

A bit body that has a cylindrical shape and is rotated around the central axis;
A plurality of excavation tips protruding from the tip surface of the bit body;
An excavation bit comprising a discharge groove that is recessed from the distal end surface of the bit body and extends in the radial direction,
Among the excavation tips, at least a part of the discharge groove is arranged in a rotation locus around the central axis of an innermost peripheral tip arranged closest to the central axis of the bit body. And drilling bit. The drill bit according to claim 1,
The excavation bit is characterized in that the discharge groove is formed so as to connect outer peripheral surfaces sandwiching a central axis of the bit body. A drill bit according to claim 2,
The excavation bit, wherein the discharge groove is formed in a Z shape or an S shape when the bit body is viewed from the front end surface side.

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