JP2002242577A - Drilling bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drilling bit wherein a gauge function is added to a cemented carbide tip located on a side of an outermost periphery of a head 2 of the bit. SOLUTION: The drilling bit 1 is composed of the head 2 and a body 3, and an end face 2a of the head 2 is provided with a fitting hole 5 wherein the button-shaped cemented carbide tip 4 is implanted. In the fitting hole 5 located on the side of the outermost periphery of the end face 2a, an angle θof aperture is constituted by partially notching a peripheral edge of a peripheral side face 2b of the head 2. The angle θ of the fitting hole 5 is set to fall within a range of 45 deg.<=θ<=135 deg. when a center point O on a shaft axis 11 is taken as a reference. The tip 4 inside the fitting hole 5 having the angle θhas the amount δ of protrusion from the side face 2b so that the gauge function for a hole wall during drilling can be added to the tip 4 in order to enhance discharge properties of excavation cuttings.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill bit applied to a bedrock, a gravel layer, and the like, and more particularly, to a mounting hole provided on the outermost peripheral side of a bit head, and implanted in the mounting hole. The gauge function of the cemented carbide tip to be used is enhanced.

[0002]

2. Description of the Related Art Heretofore, in this type of drill bit, there are cases where the bit head has a substantially circular surface and an annular surface on the drilling direction side. JP-A-5-149074 and the like belong to the latter, such as Japanese Patent Publication No. 45-10401.

[0003] The former impact bit is divided into a cemented carbide tip located on the outermost peripheral side of the bit head and a cemented carbide tip located on the inner side thereof. The gauge function is provided by projecting from the outer peripheral surface of the head.

In the latter ring bit, an auxiliary tip having a gauge function is provided on the outer peripheral side of the bit head with respect to the tip of the cemented carbide tip.

[0005] In the impact bit and the ring bit described above, the cemented carbide tip on the drilling direction side has a mounting hole even at the outermost peripheral portion without notching the outer peripheral edge of the bit body from the viewpoint of mounting strength. It has a circular state.

[0006]

However, in the above-mentioned impact bit, the projecting amount must be large in order for the tip portion of the carbide tip at the outermost periphery to have a gauge function for the hole diameter at the time of drilling. Must. As a result, there is a problem that the wear is greater than that of the carbide tips arranged in other parts, and if the relationship is not appropriate in terms of the number of implants, the amount of protrusion, etc., this leads to a shorter life.

The gauge function of the latter ring bit is enhanced by arranging the auxiliary tip. However, if the number of auxiliary tips implanted is large and the cemented carbide tip on the tip side wears out, the service life at this point is increased. Problem.

In view of the above, according to the present invention, in order to solve the above-mentioned problems, attention is paid to a mounting hole provided in the outermost peripheral portion of the bit head, and a cemented carbide chip implanted therein is provided with: An effective gauge function is added.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a button-shaped carbide tip implanted in a mounting hole formed in an end face of a bit head in a drilling direction side. Rarely, the tip of the carbide tip is improved on the premise of a drill bit protruding from the bit head.

That is, the mounting hole located on the outermost peripheral side of the bit head forms an opening angle θ by cutting off a part of the outer peripheral edge, and the opening angle θ is determined by the axial center of the mounting hole. When the center point O on the line is used as a reference, 45 ° ≦
It is set within the range of θ ≦ 135 °. In addition, the carbide tip in the mounting hole having the opening angle θ has a protrusion amount δ from the outer peripheral side surface of the bit head, when the diameter D of the carbide tip is used as a reference, 0.05 D ≦ δ ≦ 0.3D. Set within the range. These ranges have been selected primarily in relation to the gauge function and mounting stiffness of the carbide tip.

The drill bit of the present invention is preferably fixed by brazing the cemented carbide tip in the mounting hole, and the drill bit of the present invention has an end face of the bit head having an annular shape. Those that form a surface or a substantially circular surface are targeted.

[Detailed Description of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill bit applied to a bedrock, a gravel layer, and the like, and more particularly, to a mounting hole provided on the outermost peripheral side of a bit head, and implanted in the mounting hole. The gauge function of the cemented carbide tip to be used is enhanced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the drill bit of the present invention will be described below with reference to the drawings. 1 and 2 are a plan view and a front view showing a drill bit 1 according to the present invention. The drill bit 1 is composed of a bit head 2 and a body 3, and has a substantially circular shape. A button-shaped carbide tip 4 is implanted on the end face 2a, which is divided into an outer peripheral portion and an inner portion. In the case of illustration, eight pieces are arranged in pairs at the outer peripheral part, and four pieces are arranged at the inner part.

The cemented carbide tip 4 is an end face of the bit head 2.
The tip portion 4a protrudes from 2a, and various shapes such as a two-stage conical shape having a flat tip at the tip end as shown in FIGS. 1 and 2 are used as the shape. The cemented carbide tip 4 is drilled in the end face 2a of the bit head 2 and implanted in the mounting hole 5, and is usually fixed by press-fitting, brazing, or the like.

The bit body 2 discharges excavated chips generated by the excavating operation of the carbide tip 4.
At the intersection of the end face 2a and the outer peripheral side face 2b, for example, discharge grooves 6 and 7 are formed for the cemented carbide tips 4 arranged in two pieces, and the inner part of the end face 2a is formed from the rear of the body 3 Openings 8 and 9 for air or water injection are formed respectively, which communicate with the drilled connection holes (not shown).

In the end face 2a of the bit head 2, the mounting hole 5 located at the outermost peripheral portion is formed in the inclined surface portion in the case of FIG. The outer peripheral edge is partially cut out. This is to provide a gauge function for the hole wall at the time of drilling in the cemented carbide tip 4 in the mounting hole 5 so as to improve the dischargeability of excavated chips, and is necessary for implanting the cemented carbide tip 4. In the outer peripheral portion having a certain constant width, by allowing a partial cutout of the outer peripheral edge, the diameter of the carbide tip 4 located at the outermost peripheral portion is larger than the diameter of the carbide tip 4 located at the other inner side. It also means that you can set it.

FIGS. 3 and 4 are a plan view and a front view, respectively, showing another embodiment of the bit for drilling according to the present invention, which is applied to a ring bit 1 in which an end surface 2a of a bit head 2 has an annular surface shape. Things.

The ring bit 1 will be described by assigning the same reference numerals to the same portions as those of the above-described drill bit 1. In the case shown in the figure, the cemented carbide tip 4 is In the end face 2a presenting an annular shape, the outer peripheral side and the inner peripheral side are divided at a ratio of 2: 1 and are implanted in the mounting holes 5 drilled on the inclined surface portions toward the outer peripheral side and the inner peripheral side, respectively. Finally, it is fixed by press-fitting or brazing.

The bit head 2 is formed with three parts of discharge grooves 10a, 10b and 10c in order to smoothly discharge the excavated chips generated by the action of the carbide tip 4.

The ring bit 1 may incorporate another bit (not shown) on the inner peripheral side of the bit head 2, but when used alone, the inner peripheral mounting hole 5 can also be configured so that a part of the inner peripheral edge is cut out for the purpose described above.

By the way, the mounting hole 5 located on the outermost peripheral side on the end face 2a of the bit head 2 is shown in FIGS. 5 (a) (b) through 8 (a).
As shown in (b), the outer peripheral edge of the outer peripheral side surface 2b of the bit head 2 is partially cut out. As described above, this is a measure to enhance the gauge function for the hole wall at the time of drilling. FIGS. 5 (a) (b) through 8 (a) (b) show combinations of the shape of the tip portion 4a of the carbide tip 4, the inclination angle α of the end face 2a, and the implantation angle β of the carbide tip 4. FIG.

5 (a) and 5 (b), the shape of the tip portion of the carbide tip 4 has a radius of curvature that is somewhat larger than the radius of curvature (D / 2) of the hemispherical surface. Is a plane, and the inclination angle α at the end face 2a of the bit head 2 is
30 °, and the implantation angle β with respect to the axial line 11 of the carbide tip 4 with respect to the drilling direction of the bit head 2 was set to 30 °. In addition, the carbide tip 4 forms a projection amount δ with respect to the outer peripheral side surface 2b of the bit head 2, and forms an opening angle θ by partially cutting out the outer peripheral edge of the outer peripheral side surface 2b.

On the other hand, in FIGS. 6 (a) and 6 (b), the tip of the cemented carbide tip 4 has a two-stage conical shape with a flat end, and the inclination angle α Is set to 15 °, and the implantation angle β of the carbide tip 4 is set to 30 °. The carbide tip 4 forms a protrusion amount δ with respect to the outer peripheral side surface 2b of the bit head 2 in the same manner as described above, and the outer peripheral side surface of the outer peripheral side surface 2b is partially cut away to form an opening angle. Configure θ.

7 (a) and 7 (b), the tip of the cemented carbide tip 4 has a so-called tapered shape with a one-step conical shape, the tip of which is a flat surface, and the inclination angle α
Is set to 15 °, and the implantation angle β of the carbide tip 4 is set to 0 °. In the same manner as described above, the cemented carbide tip 4 forms a protruding amount δ with respect to the outer peripheral portion 2a of the bit head 2, and the opening angle is formed by partially cutting out the outer peripheral edge of the outer peripheral side surface 2b. Configure θ. In the case of this embodiment, since the cutout portion of the outer peripheral edge extends greatly in the axial direction, it is preferable to use brazing in terms of strength.

8 (a) and 8 (b), the tip of the cemented carbide tip 4 has a hemispherical shape, the inclination angle α is 0 °, and the implantation angle β of the cemented carbide tip 4 is 0 °. Is set to 30 °. Then, as in the case of the above-mentioned one, the carbide tip 4 projects from the outer peripheral portion 2a of the bit head 2 by a protrusion amount δ.
Is formed, and the outer peripheral edge of the outer peripheral side surface 2b is partially cut away to form the opening angle θ. The drilling bit 1 configured as described above is usually set within the range of 0 ° ≦ α ≦ 50 ° for the above-described inclination angle α, and is usually set to 0 ° ≦ β ≦ 45 ° for the implantation angle β. Is set within the range.

The mounting hole 5 located on the outermost peripheral side of the above-described bit head 2 forms an opening angle θ by partially cutting off the outer peripheral edge as described above.

For example, referring to FIG. 5B, when the center point O of the shaft center line 11 of the mounting hole 5 is set as a reference, the radial lines 12 and 13 are formed, but the opening angle θ is Is an angle formed when the center point O and the notch end of the outer peripheral edge are connected, and is set within a range of 45 ° ≦ θ ≦ 135 °. When the opening angle θ is less than 45 °, the effect of the gauge function in the carbide tip 4 is small, and when the opening angle θ exceeds 135 °, the mounting strength of the carbide tip 4 is impaired.

Further, the mounting hole 5 having the opening angle θ
As shown in FIG. 5A, for example, as shown in FIG. 5 (a), when the protrusion amount δ from the outer peripheral side surface 2 b is based on the diameter D of the carbide tip 4, 0.05 D ≦ δ ≦ 0.3 It is set within the range of D. If the protrusion amount δ is less than 0.05D, the dischargeability of excavation chips by the carbide tip 4 becomes poor, and the gauge function also becomes small. On the other hand, if the protrusion amount δ exceeds 0.3D, the amount of wear of the carbide tip 4 increases, and the mounting strength decreases, resulting in a problem.

On the other hand, in the above-mentioned conventional product, the notch of the mounting hole 5 is not considered at all, so that the shaft center line is not used.
11 is inevitably brought inside the bit head 2. As a result, in the conventional product, in order to secure the above-mentioned protrusion amount δ, the protrusion amount from the end face 2a of the carbide tip 4 is required.
It is necessary to increase h1. On the contrary, if the protrusion amount h1 is increased, the wear amount of the cemented carbide tip 4 is increased, and the carbide tip 4 is broken.

According to Japanese Patent Publication No. Sho 63-5549, the protrusion amount h1 is determined to be 0.6 to 1.0 D with respect to the diameter D of the cemented carbide tip 4. Therefore, the conventional drill bit 1 has a configuration in which it is difficult to secure the protrusion amount δ within the range of the protrusion amount h1 described above.
In short, a conventional conventional product has a configuration in which a gauge function is hardly added to the outermost carbide tip 4.

[0031]

As described above, according to the present invention, the mounting hole 4 formed on the end face 2a of the bit head 2 at the outermost peripheral side is such that the outer peripheral edge of the bit head 2 is partially cut away. Is formed within the specific range, and the carbide tip 4 implanted in the mounting hole 4 having the specific angle θ projects the specific range of the projecting amount δ with respect to the outer peripheral side surface 2 b of the bit head 2. Is constituted.

Therefore, the drill bit 1 of the present invention
Since the gauge function for the hole wall at the time of drilling is added to the carbide tip 4 located on the outermost peripheral side,
In the drilling work of a stratum in a gravel layer or the like, there is an advantage that discharge of excavation debris is improved and excavation efficiency is improved.

[0033]

[Brief description of the drawings]

FIG. 1 is a plan view of a main part showing an embodiment of a drill bit according to the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is a plan view of a main part showing another embodiment of the drill bit of the present invention.

FIG. 4 is a front view of FIG. 4;

FIG. 5 is an explanatory view showing an implanted state located at the outermost peripheral portion of the bit head in one embodiment of the drill bit of the present invention, wherein (a) is an explanatory view from the front, and (b) is an upward view. FIG.

FIG. 6 is an explanatory view showing an implanted state located at the outermost peripheral portion of the bit head in another embodiment of the drill bit of the present invention, wherein (a) is an explanatory view from the front, and (b) is an upper view. It is explanatory drawing from a direction.

FIG. 7 is an explanatory view showing an implanted state located at the outermost peripheral portion of the bit head in another embodiment of the drill bit of the present invention, wherein (a) is an explanatory view from the front direction, and (b) is an upper view. It is explanatory drawing from a direction.

FIG. 8 is an explanatory view showing an implanted state located at an outermost peripheral portion of a bit head in still another embodiment of the drill bit of the present invention, wherein (a) is an explanatory view from the front, and (b) is an explanatory view. It is explanatory drawing from an upper direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drilling bit 2 Bit head 2a End face 2b Outer side 3 Body 4 Carbide tip 4a Tip 4b Implanted part 5 Mounting hole 6 Drain groove 7 Drain groove 8 Opening 9 Opening 10a Drain groove 10b Drain groove 10c Drain groove 11 shaft Direction line 12 Radial line 13 Radial line

Claims (3)

[Claims] A button-shaped cemented carbide tip is implanted in a mounting hole provided on an end face of the bit head on the drilling direction side, and a tip portion of the cemented carbide tip projects from the bit head. In the drilling bit, the mounting hole located on the outermost peripheral side of the bit head forms an opening angle θ by cutting out a part of the outer peripheral edge, and the opening angle θ is Is set within the range of 45 ° ≦ θ ≦ 135 ° with respect to the center point O on the axis center line of the axis, and the cemented carbide tip in the mounting hole forming the opening angle θ is a A drill bit characterized in that the amount of protrusion δ from the outer peripheral side is set within a range of 0.05 D ≦ δ ≦ 0.3 D, based on the diameter D of the carbide tip. 2. The cemented carbide tip, in the mounting hole,
2. The drill bit according to claim 1, wherein the bit is fixed by brazing. 3. The drill bit according to claim 1, wherein an end surface of the bit head forms an annular surface or a substantially circular surface.