WO2016114344A1 - Drill tip and drill bit - Google Patents

Abstract

In the drill tip of the present invention, the tip body of the drill tip has a cylindrical or disc-shaped rear end part, an intermediate part having a smaller outside diameter than that of the rear end part, and a leading end part in which the outer diameter gradually decreases from the centerline of the tip toward the leading end. The tip body is covered by a hard layer from the surface of the leading end part of the tip body to the outer periphery of the intermediate part. The outside diameter of the hard layer at the intermediate part is equal to the outside diameter of the rear end part.

Description

Drilling tip and drilling bit

The present invention relates to a drilling tip that is attached to a distal end portion of a drilling bit to perform excavation, and a drilling bit in which such a drilling tip is attached to the distal end portion.
This application claims priority based on Japanese Patent Application No. 2015-005175 filed in Japan on January 14, 2015 and Japanese Patent Application No. 2016-004695 filed in Japan on January 13, 2016. The contents are incorporated herein.

Such a drilling tip is known in which a tip of a tip body made of cemented carbide is coated with a hard layer made of a sintered body of polycrystalline diamond harder than the tip body. Here, in Patent Document 1, such a hard layer is provided on the tip portion of the chip body having a cylindrical rear end portion and a hemispherical tip portion having an outer diameter that decreases toward the tip side. A covered excavation tip and an excavation bit in which such a excavation tip is attached so that the rear end portion of the tip body is buried in an attachment hole formed in the front end portion of the bit body have been proposed. Patent Document 2 describes a method for manufacturing such a polycrystalline diamond sintered body, and Patent Documents 3 and 4 describe a manufacturing apparatus.

US Pat. No. 5,575,342 U.S. Pat. No. 3,141,746 US Pat. No. 3,913,280 U.S. Pat. No. 3,745,623

By the way, as shown also in this patent document 1, in the drilling chip | tip with which the hard layer which consists of the above polycrystalline diamond sintered bodies was coat | covered, the thickness of this hard layer is the rear end of a chip | tip main body. It is common in the manufacturing method of such excavation tip that the tip is thicker at the tip of the tip located on the center line of the cylinder formed by the portion, and becomes thinner from the tip toward the outer peripheral side of the tip. However, on the other hand, when attaching such a drilling tip to the drilling bit, if the outer diameter of the rear end portion of the tip body is larger than the inner diameter of the mounting hole, this rear end portion is It is also common to grind the outer periphery of the excavation tip in order to be buried in the mounting hole.

However, in such a polished excavation tip, the thin portion of the hard layer on the outer periphery of the tip end of the tip body is polished to remove the hard layer, and the surface of the tip body made of cemented carbide is exposed. There is a risk of becoming. And when such a drilling tip is attached to the bit body of the drilling bit so that the rear end portion of the tip body is buried in the mounting hole, not only the portion covered with the hard layer but also the surface of the tip body as described above. The outer periphery of the exposed tip end portion is exposed from the tip end surface of the bit body.

Therefore, when excavation is performed using an excavation bit equipped with such an excavation tip, the surface of the outer periphery of the tip end of the tip body exposed from the tip end surface of the bit main body is exposed due to contact with crushing waste generated during excavation. As a result, the tip of the excavation tip is broken while the hard layer remains on the inner peripheral surface of the tip. For this reason, the excavation tip reaches the end of its life in a short time without fully exhibiting the high wear resistance of the hard layer made of the polycrystalline diamond sintered body having high hardness and high cost.

The present invention has been made under such a background, and when the outer diameter of the rear end portion of the tip body is formed larger than the inner diameter of the mounting hole, the drill bit can be polished even if the outer periphery of the drill tip is polished. In addition to providing a long-life drilling tip that fully utilizes the high wear resistance of the hard layer, the tip body surface is not exposed at the exposed portion of the tip of the tip, and such a drilling tip is attached. Another object of the present invention is to provide a drill bit that has a long life and can perform efficient drilling.

In order to solve the above problems and achieve such an object, the excavation tip of the present invention is an excavation tip that is attached to the distal end portion of an excavation bit and performs excavation. A hard layer made of a diamond sintered body that is harder than the chip body to be coated, the chip body having a rear end portion that has a columnar shape or a disk shape centered on the chip center line, and the rear end portion On the other hand, an intermediate portion having a smaller outer diameter than the rear end portion located on the tip end side in the tip center line direction, and further toward the tip end side located on the tip side in the tip center line direction with respect to the intermediate portion. A tip portion whose outer diameter from the tip center line gradually decreases, and the hard layer is covered from the tip portion surface of the tip body to the outer periphery of the intermediate portion. The outer diameter of the serial hard layer is characterized in that it is equal to the outer diameter of the rear end portion of the chip body.

The excavation bit of the present invention is an excavation bit in which such excavation tip is attached to the distal end portion of the bit body, and an attachment hole is formed in the distal end portion of the bit body. The rear end portion of the chip main body and at least a part of the intermediate portion covered with the hard layer are embedded in the mounting hole and attached.

In the excavation tip of the present invention, an intermediate portion having a smaller outer diameter than the rear end portion between the cylindrical or disc-like rear end portion of the tip body and the front end portion whose outer diameter decreases toward the front end side. The outer diameter of the distal end portion gradually decreases from the middle portion toward the distal end side. The hard layer is covered from the front end portion to the outer periphery of the intermediate portion, and the outer diameter of the hard layer in the intermediate portion is equal to the outer diameter of the rear end portion of the chip main body. Even when the outer circumference of the excavation tip is polished when the outer diameter of the section is larger than the inner diameter of the mounting hole, the outer circumference of the intermediate section is covered with a hard layer having a thickness that is the difference between the outer diameter of the rear end section and the intermediate section. Left behind.

Therefore, like the excavation bit of the present invention, such a excavation tip is embedded in the mounting hole at the rear end portion of the tip body and at least a part of the intermediate portion covered with the hard layer. By attaching it, it is possible to prevent the surface of the chip body having a lower hardness than the hard layer from being exposed and exposed from the front end surface of the bit body. It is possible to prevent a situation in which wear progresses due to contact and breaks the tip of the excavation tip. For this reason, it is possible to provide a drilling tip and a drilling bit having a long life by fully exhibiting the wear resistance of the hard layer made of a diamond sintered body, and to perform efficient drilling.

Here, if the outer diameter of the intermediate portion is smaller than the rear end portion, the outer diameter becomes smaller toward the front end side, for example, a truncated cone shape, or if the front end portion is hemispherical, The outer peripheral surface smoothly connected to the tip end portion may be a curved surface. On the other hand, like the rear end portion, by forming a columnar shape or a disk shape centered on the chip center line, the layer thickness in the radial direction perpendicular to the chip center line of the hard layer in the state where the hard layer is coated is increased. It can be constant over the chip centerline direction. For this reason, in the excavation bit, no matter how far the portion covered with the hard layer of this intermediate portion is buried in the mounting hole, sufficient wear resistance is ensured for the excavation tip of the portion exposed from the tip end surface of the bit body be able to. Therefore, it is preferable that the intermediate portion has a columnar shape or a disc shape centering on the chip center line having a smaller outer diameter than the rear end portion.

It should be noted that the width of the hard layer coated on the outer periphery of the intermediate portion in the direction of the chip center line is preferably in the range of 1 mm to 5 mm. If the width is less than 1 mm, the surface of the tip body may be exposed when the excavation tip is shallowly buried in the attachment hole or when the opening of the attachment hole is worn during excavation. . On the other hand, if the width of the hard layer exceeds 5 mm, if the outer diameter of the excavation tip is larger than the inner diameter of the mounting hole, it takes much time and labor to polish to a predetermined outer diameter. Further, it is desirable that the thickness of the hard layer coated on the outer periphery of the intermediate portion is in the range of 300 μm to 1200 μm.

Further, it is preferable that a width of the portion buried in the mounting hole in the hard layer coated on the intermediate portion in the chip center line direction is 0.5 mm to 4.5 mm. Further, in the excavation bit, it is preferable that a width in the tip center line direction of a portion of the hard layer covered by the intermediate portion that is not buried in the attachment hole is 0.5 mm to 1.0 mm. .

As described above, according to the present invention, when the excavation tip is attached to the distal end surface of the excavation bit, the surface of the low-altitude chip body is prevented from being exposed at the portion exposed from the distal end surface of the excavation bit. be able to. As a result, it is possible to extend the life of the excavation tip and the excavation bit by the hard layer having high wear resistance and perform efficient excavation.

It is sectional drawing which shows one Embodiment of the excavation chip | tip of this invention (a broken line is a boundary of the front-end | tip part and intermediate part of a chip | tip main body). It is sectional drawing which shows one Embodiment of the excavation bit of this invention which attached the excavation tip of embodiment shown in FIG. 1 to the front-end | tip part. It is an expanded sectional view which shows the part to which the excavation chip | tip was attached in embodiment shown in FIG. 2 (a broken line is a boundary of the front-end | tip part and intermediate part of a chip | tip main body).

FIG. 1 is a cross-sectional view showing an embodiment of the excavation tip 1 of the present invention, and FIG. 2 is a cross-sectional view showing an embodiment of the excavation bit of the present invention to which the excavation tip 1 of this embodiment is attached. 3 is an enlarged cross-sectional view showing a portion where the excavation tip 1 is attached in the excavation bit of this embodiment. The excavation tip 1 of this embodiment includes a tip body 2 made of a hard material such as cemented carbide, a hard layer 3 made of a diamond sintered body harder than the tip body 2 and covering the surface of the tip body 2. It has.

The chip body 2 has a rear end portion (lower portion in FIGS. 1 and 3) 2A having a columnar shape or a disc shape centered on the chip center line C, and a tip end portion (in FIGS. 1 and 3). In the present embodiment, the upper portion 2B has a hemispherical shape having a center slightly on the tip center line C with a radius slightly smaller than the radius of the cylinder or disk formed by the rear end portion 2A. The outer diameter from the chip center line C is formed so as to gradually decrease. That is, the excavation tip 1 of this embodiment is a button tip. In addition, it is preferable that the radius of the rear end in the tip center line C direction of the front end portion 2B is a value smaller than the radius of the rear end portion 2A by a layer thickness T described later.

Further, an intermediate portion 2C having an outer diameter slightly smaller than the outer diameter of the cylinder or disk formed by the rear end portion 2A is formed between the rear end portion 2A and the front end portion 2B. In the chip body 2, the rear end portion 2A, the front end portion 2B, and the intermediate portion 2C are integrally formed of a hard material such as the above-mentioned cemented carbide. Further, the cross section perpendicular to the chip center line C of the chip body 2 has a circular shape centering on the chip center line C in any of the rear end portion 2A, the front end portion 2B, and the intermediate portion 2C.

Here, in the present embodiment, the intermediate portion 2C has a columnar shape or a disc shape with the chip center line C as the center like the rear end portion 2A, and is coaxial with the rear end portion 2A so that the outer diameter is small. Is formed. At the upper end portion of the rear end portion 2A corresponding to the boundary position between the rear end portion 2A and the intermediate portion 2C, a table surface 2D which is an annular flat surface facing the tip side of the chip center line C (upper side in FIGS. 1 and 3). Is formed. By providing such a table surface 2D, the hard layer 3 having a sufficient thickness can be formed over the entire intermediate portion 2C. The table surface does not need to be a surface perpendicular to the chip center line C, and may be inclined by 0 to 45 ° (preferably 0 to 30 °) with respect to the radial direction, for example. Further, the table surface 2D and the outer peripheral surface of the intermediate portion 2C may be connected by a curved surface or an inclined surface. In other words, in the cross section passing through the chip center line C of the chip body 2, it is not necessary that the inner peripheral end of the table surface 2D and the rear end of the outer peripheral surface of the intermediate part 2C are connected at right angles, but by an arc, a straight line, etc. It may be connected. Further, in the cross section passing through the chip center line C of the chip body 2, the tip of the outer peripheral surface of the rear end portion 2A and the rear end of the outer peripheral surface of the intermediate portion may be connected by a concave curve. That is, the table surface 2D may be an annular curved surface.

Furthermore, in the present embodiment, the radius of the hemisphere formed by the tip 2B is made equal to the radius of the cylinder or disk formed by the intermediate 2C, and the hemisphere formed by the surface of the tip 2B is the outer peripheral surface of the intermediate 2C. It is formed to be smoothly connected to the cylindrical surface.

The hard layer 3 coated on the surface of the chip body 2 is a cylindrical surface formed by the hemispheric surface formed by the surface of the tip 2B and the outer periphery of the intermediate 2C from the tip 2B to the outer periphery of the intermediate 2C. The outer peripheral surface of the rear end portion 2A and the rear end surface of the chip body 2 are not covered. In the present embodiment, the hard layer 3 is covered over the entire outer peripheral surface of the intermediate portion 2C. The hard layer 3 has a radius from the chip center line C of the surface of the hard layer 3 at a portion covered by the outer peripheral surface of the intermediate portion 2C, and a radius from the chip center line C of the outer peripheral surface of the rear end portion 2A. Is equal to. That is, the outer diameter of the hard layer 3 in the intermediate part 2C is made equal to the outer diameter of the rear end part 2A of the chip body 2.

The hard layer 3 has a diamond particle size constituting the diamond sintered body and a content for each particle size, a binder metal composition and content, or a composition and content of additive particles other than diamond particles. The seeded hard layer may be a single hard layer, or may be a hard layer of two layers as shown in FIGS. 1 and 3 in which these elements are different, or a hard layer of a multilayer structure of three or more layers. When the hard layer 3 is composed of a plurality of layers, as shown in FIGS. 1 and 3, the outermost layer covering the tip 2B and the outermost layer covering the intermediate portion are composed of one layer. Is preferred. Sintering of the excavation tip 1 in which the hard layer 3 is coated on the tip body 2 is basically performed in the diamond stable region. A known sintering method as described in Patent Literature 2, Patent Literature 3 4 is possible with the device described in 4.

However, the outermost layer of the hard layer 3 has higher hardness than the layer adjacent to the inner side in order to achieve high wear resistance and relaxation of the stress of the diamond sintered body by the hard layer 3, that is, the layer adjacent to the inner side. It is desirable that the hardness is lower than that of the outermost layer. In addition, as described above, the hard layer 3 has a thick layer at the tip on the tip center line C of the tip 2B, and the layer thickness decreases from the tip toward the outer peripheral side of the tip 2B.

The excavation bit to which the excavation tip 1 is attached is provided with a bit body 11 formed of a steel material or the like and having a substantially bottomed cylindrical shape centering on an axis O as shown in FIG. The bottom part is a tip part (upper part in FIG. 2) and the excavation tip 1 is attached.
An internal thread portion 12 is formed on the inner periphery of the cylindrical rear end portion (lower portion in FIG. 2). The excavation rod connected to the excavator is screwed into the female screw portion 12 to transmit the striking force and thrust toward the front end side in the direction of the axis O, and the rotational force around the axis O, so that the excavation tip 1 The rock mass is crushed to form an excavation hole.

The front end portion of the bit body 11 has a slightly larger outer diameter than the rear end portion, and a plurality of discharge grooves 13 extending in parallel to the axis O are spaced apart in the circumferential direction on the outer periphery of the front end portion. Is formed. Crushed debris generated by crushing the rock by the excavation tip 1 is discharged to the rear end side through the discharge groove 13. A blow hole 14 is formed along the axis O from the bottom surface of the female screw portion 12 of the bottomed bit body 11. The blow hole 14 branches obliquely at the tip of the bit body 11 and opens at the tip surface of the bit body 11, and ejects a fluid such as compressed air supplied via the drilling rod to Promote emissions.

Furthermore, the front end surface of the bit body 11 has a circular face surface 15 centering on an axis O perpendicular to the inner peripheral axis O, and a rear end side located on the outer periphery of the face surface 15 toward the outer periphery. And a frustoconical gauge surface 16 facing toward the surface. The blow hole 14 opens to the face surface 15, and the tip of the discharge groove 13 opens to the gauge surface 16. Furthermore, a plurality of mounting holes 17 having a circular cross section are formed on the face surface 15 and the gauge surface 16 so as to avoid the openings of the blow holes 14 and the discharge grooves 13 respectively. It is formed vertically.

Then, the excavation tip 1 is inserted into the mounting hole 17 as shown in FIG. 3, and the rear end portion 2A of the tip body 2 and the rear end portion 2A of the intermediate portion 2C covered with the hard layer 3 are provided. The excavation tip 1 is fixed to the mounting hole 17 by being fitted or brazed by press fitting, shrink fitting or the like in a state where at least a part of the side is buried in the mounting hole 17. That is, the excavation tip 1 is embedded in the attachment hole 17 and attached.

Therefore, the remaining portion of the intermediate portion 2C on the front end portion 2B side and the front end portion 2B are respectively protruded from the front end surface of the bit body 11, that is, the face surface 15 and the gauge surface 16, and further the chip center line C is perpendicular to the face surface 15 and the gauge surface 16. Here, in FIG. 3, a part of the intermediate part 2 </ b> C is buried in the mounting hole 17, but the whole intermediate part 2 </ b> C may be buried.

As described above, in the excavation tip 1 having the above-described configuration and the excavation bit in which the excavation tip 1 is attached to the distal end portion, the rear end of the excavation tip 1 on the distal end side of the rear end portion 2A having a large diameter of the tip body 2 is arranged. An intermediate portion 2C having a smaller diameter than the portion 2A is provided, and a distal end portion 2B for excavating the outer diameter from the tip center line C with a smaller outer diameter from the tip center line C is provided on the further distal end side of the intermediate portion 2C. The hard layer 3 is coated on the surface of 2B and the intermediate part 2C, and the outer diameter of the hard layer 3 on the outer periphery of the intermediate part 2C is made equal to the rear end part 2A.

For this reason, when the outer diameter of the excavation tip 1 is larger than the inner diameter of the mounting hole 17, the outer peripheral surface of the rear end portion 2A and the surface of the hard layer 3 on the outer periphery of the intermediate portion 2C in the tip body 2 of the excavation tip 1 are polished. Even if the grinding allowance is within the range of the outer diameter difference between the rear end portion 2A and the intermediate portion 2C, that is, the thickness of the hard layer 3 on the outer periphery of the intermediate portion 2C, the hard layer 3 is placed on the outer periphery of the intermediate portion 2C. Left behind. This is the same even when the outer diameter of the sintered excavation tip 1 can be buried in the mounting hole 17 as it is, and is not polished.

Therefore, even if the outer periphery of the excavation tip 1 is polished in this way, the state where the rear end 2A of the tip body 2 and at least a part of the intermediate portion 2C are buried in the mounting hole 17 of the bit body 11 is shown in FIG. As described above, only the portion covered with the hard layer 3 of the excavation tip 1 is exposed from the face surface 15 and the gauge surface 16 which are the front end surfaces of the bit body 11 and is made of a cemented carbide or the like having a lower hardness than the hard layer 3. The surface of the chip body 2 is not exposed.

For this reason, it prevents that the rear end side part of the front-end | tip part 2B of the chip | tip body 2 and the front-end | tip side part of the intermediate | middle part 2C are worn away by direct contact with the crushing waste during excavation, and the excavation tip 1 is hard. It is possible to prevent a situation where the layer is broken while leaving the layer. Therefore, according to the excavation tip 1 and the excavation bit having the above-described configuration, the wear resistance of the hard layer 3 can be sufficiently exhibited to enable long-term excavation, and efficient and economical excavation work can be performed.

In addition, it is preferable that the width S in the chip center line C direction of the portion buried in the mounting hole 17 in the hard layer 3 covered with the intermediate portion 2C is 0.5 mm to 4.5 mm. By setting the width S to 0.5 mm or more, the periphery of the opening of the mounting hole 17 of the face surface 15 or the gauge surface 16 is worn by excavation debris during excavation, and the portion where the excavation tip 1 is buried is Even if it is exposed, the hard layer 3 is exposed, so that the surface of the chip body 2 is not exposed. As a result, the excavation tip 1 can be prevented from being broken, so that the wear resistance of the hard layer 3 covering the tip 2B can be sufficiently exerted to enable long-term excavation. On the other hand, if the width S exceeds 4.5 mm, the region of the hard layer 3 increases, and it takes a lot of time and labor when polishing the outer periphery of the excavation tip 1, which is not preferable.

Further, of the hard layer 3 covered with the intermediate portion 2C, the width L in the chip center line direction of the portion not buried in the mounting hole 17 (from the face surface 15 and the gauge surface 16 of the hard layer 3 to the tip portion 2B). And the projecting length to the boundary between the intermediate portion 2C) is preferably 0.5 mm to 1.0 mm. By setting the width L to 0.5 mm or more, only the portion of the excavation tip 1 covered with the hard layer 3 is exposed from the face surface 15 and the gauge surface 16 which are the front end surfaces of the bit body 11, and is more than the hard layer 3. The surface of the chip body 2 made of a low hardness cemented carbide or the like is not exposed. As a result, the excavation tip 1 can be prevented from being broken, so that the wear resistance of the hard layer 3 covering the tip 2B can be sufficiently exerted to enable long-term excavation. On the other hand, when the width L exceeds 1.0 mm, the region of the hard layer 3 increases, and it takes a lot of time and labor to polish the outer periphery of the excavation tip 1, which is not preferable.

Further, in the excavation tip 1 of the present embodiment, the intermediate portion 2C of the tip body 2 has a columnar shape or a disc shape centered on the tip centerline C that is the centerline of the columnar shape or disc formed by the rear end portion 2A. The rear end portion 2A and the intermediate portion 2C are coaxial and have a multi-stage columnar shape or a multi-stage disk shape whose diameter is reduced by one step toward the tip side of the chip body 2. For this reason, since the layer thickness of the hard layer 3 on the outer periphery of the intermediate part 2C can be made constant in the direction of the chip center line C, the chip body can be used no matter where the excavation chip 1 is buried in the mounting hole 17. 2 where the intermediate portion 2C protrudes from the face surface 15 or the gauge surface 16, the thickness of the hard layer 3 on the outer periphery can be made constant, and sufficient wear resistance can be ensured in this portion. It becomes possible.

However, the intermediate portion 2C is not formed in a columnar shape or a disk shape in this way, for example, it is formed in a truncated cone shape with the tip center line C gradually decreasing in outer diameter toward the tip side, or Similarly, even if the outer diameter gradually decreases toward the distal end side, the outer peripheral surface along the chip center line C may have a convex curve shape or a concave curve shape. Even in these cases, the layer thickness of the hard layer 3 becomes thicker toward the tip side, so that the wear resistance of the hard layer 3 in the portion where the intermediate portion 2C of the chip body 2 protrudes from the face surface 15 or the gauge surface 16 is improved. It can be secured sufficiently.

The width of the hard layer 3 covered on the outer periphery of the intermediate portion 2C in this way in the direction of the chip centerline C indicated by the symbol W in FIG. 1 (in the present embodiment, it is intermediate between the tip portion 2B indicated by the broken line in FIGS. 1 and 3) If the width in the tip center line C direction of the intermediate portion 2C between the boundary with the portion 2C and the boundary between the rear end portion 2A and the intermediate portion 2C) is too small, the excavation tip 1 is shallowly buried in the mounting hole 17 Or when the periphery of the opening of the mounting hole 17 in the bit body 11 is worn during excavation, the surface of the chip body 2 may be exposed (the width S is sufficient). There is a possibility that it cannot be secured). On the other hand, if the width W of the hard layer 3 is too large, it takes a lot of time and labor to polish the outer periphery of the excavation tip 1. Therefore, the width W is desirably in the range of 1 mm to 5 mm, and more desirably in the range of 2.0 mm to 4.0 mm.

Similarly, the thickness of the hard layer 3 on the outer periphery of the intermediate portion 2C indicated by the symbol T in FIG. 1 is preferably in the range of 300 μm to 1200 μm, and more preferably in the range of 500 μm to 1000 μm. . If the layer thickness T is so thin that it is less than 300 μm, there is a possibility that the excavation tip 1 cannot be provided with a sufficient life no matter how hard layer 3 is covered. On the other hand, if the layer thickness T of the hard layer 3 is too thick so as to exceed 1200 μm, the volume of the hard layer 3 occupying the portion that is buried in the mounting hole 17 and does not contribute to wear prevention or excavation increases. Is. In addition, in the whole hard layer 3 formed in the intermediate part 2C, it is preferable that the layer thickness T becomes in said desirable range.

Here, the position of the rear end of the intermediate portion 2C that is the boundary between the intermediate portion 2C and the rear end portion 2A in the chip center line C direction, and the front end of the intermediate portion 2C that is the boundary between the intermediate portion 2C and the front end portion 2B. The position is specified as follows. When the diameter of the lower end surface of the rear end portion 2A is α, the rear end of the portion having a diameter smaller than 93.3% of α is the boundary between the intermediate portion 2C and the rear end portion 2A (the rear end of the intermediate portion 2C). And When the diameter of the rear end of the intermediate portion 2C is β (β ≦ α × 0.933), the portion where the diameter is 91.1% of β is the boundary between the intermediate portion 2C and the front end portion 2B (intermediate portion). 2C tip). That is, the diameter γ of the rear end of the tip portion 2B is γ = β × 0.911.

Further, the ratio h / H of the length h from the front end of the front end portion 2B to the rear end of the intermediate portion 2C with respect to the total length H of the chip main body 2 in the direction of the chip center line C is preferably 0.45 to 0.80. 0.50 to 0.75 is more preferable. By setting h / H within this range, the above-described effects can be achieved more reliably.

In the excavation tip 1 of the present embodiment, the case where the present invention is applied to a button type excavation tip in which the tip 2B of the tip body 2 is hemispherical as described above has been described. A so-called ballistic type drilling tip that has a bullet shape, and the rear end side of the tip part is conical and decreases in diameter toward the tip side, and the tip is smaller than the cylindrical rear end part of the tip body The present invention can also be applied to a so-called spike type drilling tip having a spherical shape with a small radius.

Next, in the excavation tip and excavation bit of the present invention, the difference in effect due to the difference in the width W of the hard layer 3 in the above-described embodiment will be demonstrated with examples. In this example, the width W of the hard layer 3 (corresponding to the width of the intermediate layer 2C), the thickness T of the hard layer, the face surface 15 and the gauge surface 16 to the tip 2B shown in Table 1 are shown in Table 1. 6 types of excavation tips 1 having a protruding length L (a protruding length of the intermediate portion 2C) L to the boundary between the intermediate portion 2C and the intermediate portion 2C were manufactured. Six excavation bits were manufactured in which the excavation tip 1 was attached by burying the rear end portion 2A and the intermediate portion 2C of the tip main body 2 in an attachment hole 17 formed in the tip end portion of the bit main body 11. These are referred to as Examples 1 to 6. As a comparative example for Examples 1 to 6, the width W is 0 mm, that is, the chip body has a hemispherical shape having a radius that is the same as that of the rear end portion without having an intermediate portion having a smaller diameter than the rear end portion. There were also manufactured one having a front end portion formed directly on the front end side of the rear end portion and one having the width W of 0.5 mm. These are referred to as Comparative Examples 1 and 2. Furthermore, in the same excavation tip as in Example 1, two types of excavation bits were manufactured by changing only the thickness T of the hard layer 3 on the outer periphery of the intermediate portion 2C. These are referred to as Comparative Examples 3 and 4. Moreover, in the same excavation tip as in Example 2, two types of excavation bits were manufactured in which the protruding length L of the intermediate portion 2C was changed. These are referred to as Comparative Examples 5 and 6.

In each of the excavation tips attached to the excavation bits of Examples 1 to 6 and Comparative Examples 1 to 6, the outer diameter of the hard layer 3 covered with the tip 2B is a cylinder formed by the rear end 2A of the tip body 2. Alternatively, it is a button-type drilling tip having a hemispherical diameter equal to the outer diameter of the disc, and this diameter was 11 mm. The thickness T of the hard layer 3 on the outer periphery of the intermediate part 2C of the chip body 2 is 400 μm in Examples 1 to 3, Comparative Examples 1, 2, 5, and 6, 350 μm in Example 4, and 1100 μm in Example 5. In Example 6, it was set to 600 μm, in Comparative Example 3 to 150 μm, and in Comparative Example 4 to 1500 μm. The thickness in the tip center line C direction at the tip end of the tip 2B indicated by the symbol P in FIG. 1 is 1200 μm in Examples 1 to 3, Comparative Examples 1, 2, 5, and 6, 800 μm in Example 4, and in Example 5. 1150 μm, Example 6 was 1000 μm, Comparative Example 3 was 600 μm, and Comparative Example 4 was 1800 μm. Accordingly, in each of the examples and comparative examples, the outer diameter (diameter) of the rear end portion 2A of the chip body 2 is 11 mm, and the outer diameter of the intermediate portion 2C except for the comparative example 1 is 10.2 mm (the tip portion 2B is configured). The diameter of the hemisphere was 10.2 mm, and the length of the rear end 2A in the chip center line C direction was 7.5 mm.

The hard layer 3 has a two-layer structure as shown in FIG. The outer layer of the hard layer 3 contains 30 vol% of diamond particles having a particle diameter of 2 to 4 μm, 70 vol% of diamond particles having a particle diameter of 20 to 40 μm, and 15 vol% of a metal binder of Ni: 100 wt% without containing additive particles. It was set as the high hardness layer formed by the content rate with respect to the whole layer containing particles. The average thickness of the outer layer of the hard layer 3 is 800 μm in Examples 1 to 3, Comparative Examples 1, 2, 5, and 6, 500 μm in Example 4, 900 μm in Example 5, 800 μm in Example 6, and Comparative Example 3 In Comparative Example 4, it was set to 1600 μm. The inner layer of the hard layer 3 is formed of 60 vol% of diamond particles having a particle size of 4 to 6 μm, 40 vol% of TaC particles of 0.5 to 2 μm as additive particles, and 10 vol% of Co: 100 wt% metal binder. A low hardness layer was used. The average layer thickness of the inner layer of the hard layer 3 is 200 μm in Examples 1 to 3, Comparative Examples 1, 2, 5, and 6, 350 μm in Example 4, 200 μm in Example 5, 300 μm in Example 6, and Comparative Example 3 4 was 120 μm. The average layer thickness of the outer layer of the hard layer 3 is the center of the hemisphere formed by the layer thickness in the direction of the tip center line C in the cross section along the tip center line C and the tip of the excavation tip as shown in FIG. (On the intersection of the dotted line indicating the boundary between the intermediate part 2C and the tip part 2B in FIG. 1 and the chip center line C) on the two straight lines intersecting the chip center line C at an intersection angle of 30 ° and 60 ° It was set as the average value with the layer thickness in the position. Moreover, the average layer thickness of the inner layer of the hard layer 3 is the crossing angle of 30 ° and 60 ° with respect to the chip center line C through the layer thickness in the chip center line direction and the center of the hemisphere formed by the tip of the excavation chip. The average value of the layer thicknesses at positions on two intersecting straight lines was used.

Further, in the excavation bits of Examples 1 to 6 and Comparative Examples 1 to 6, two such excavation tips are combined on the face surface 15 and 5 on the gauge surface 16 of the bit body 11 having a bit diameter of 45 mm. Seven were attached. Note that the protruding lengths from the face surface 15 and the gauge surface 16 to the boundary between the tip 2B and the intermediate portion 2C of the chip body 2 shown in FIG. 3 by Examples 1 to 3, 5 and Comparative Examples 2 to 4 was 1 mm, Example 4 was 0.5 mm, Example 6 was 0.8 mm, Comparative Example 5 was 3 mm, and Comparative Example 6 was 0 mm. In Comparative Example 1, the rear end 2A is exposed by 1 mm in the chip center line C direction from the boundary between the rear end 2A and the front end 2B (from the face surface 15 and the gauge surface 16 to the rear end 2A and the front end. The excavation tip was attached to the bit body 11 so that the distance to the boundary with 2B was 1 mm.

These excavation bits perform excavation work to excavate a 4 m excavation hole in a copper mine with an average uniaxial compressive strength of 150 MPa made of medium hard rock, and the total excavation distance (m) until the excavation tip reaches the end of its life. And the form of damage of the excavation tip and bit at the end of excavation was confirmed. The excavation conditions are as follows: the excavator is model number H205D manufactured by TAMROCK, the striking pressure is 160 bar (16 MPa), the feed pressure is 80 bar (8 MPa), the rotational pressure is 55 bar (5.5 MPa), and water is discharged from the blow hole. The supplied water pressure was 18 bar (1.8 MPa). The results are shown in Table 1.

 

 

From this result, in the excavation bit attached with the excavation tip of Comparative Examples 1 and 2 in which the width W of the hard layer 3 is short or 0, even in Comparative Example 2 with a long excavation distance, the root of the excavation tip (from the surface of the bit body) The tip body 2 was worn out from the protruding portion (on the bit body surface side), and the tip body 2 was swept away, so that the total excavation distance was less than 400 m, that is, 100 holes could not be excavated, and the lifetime was reached. Even in the excavation bit to which the excavation tip of Comparative Example 3 having a small thickness T of the hard layer 3 was attached, wear occurred from the base of the excavation tip, resulting in a shorter total excavation distance compared to Examples 1 to 6. . In Comparative Example 4 in which the thickness T of the hard layer 3 was large, the total excavation distance was shorter than in Examples 1 to 6. In Comparative Example 5 in which the protruding length L of the intermediate portion 2C is long, the length of the portion embedded in the bit body 11 of the intermediate portion 2C (S in FIG. 3) is short and breaks at the base of the excavation tip. Further, in Comparative Example 6 in which the protruding length L of the intermediate portion 2C is 0 mm, that is, only the distal end portion 2B protrudes from the face surface 15 and the gauge surface 16, the bit body 11 is worn out in advance, and the drill body inserts from the bit body 11 Was the result.
On the other hand, in the excavation bit to which the excavation tips of Examples 1 to 6 were attached, although some excavation tips were broken in Example 1, the excavation of 100 holes or more was performed until the lifetime was reached due to normal wear. Was possible. In Examples 2 and 3, the thickness T of the hard layer 3 and the protruding length L of the intermediate portion 2C are the same, and the life of the hard layer 3 having a small width W is extended by 2-3 times or more. I was able to.

As described above, according to the present invention, it is possible to prevent the surface of the low-altitude chip body from being exposed at the portion exposed from the tip surface of the excavation bit, and the excavation chip is formed by the hard layer having high wear resistance. In addition, it is possible to extend the life of the drill bit and perform efficient drilling.

DESCRIPTION OF SYMBOLS 1 Drilling chip 2 Chip body 2A Rear end part of chip body 2 2B Tip part of chip body 2 2C Intermediate part of chip body 2 2D Annular table surface 3 Hard layer 11 Bit body 15 Face surface (tip surface) of bit body 11
16 Gauge surface (tip surface) of bit body 11
17 Mounting hole C Chip center line O Axis of bit body 11 W Width of hard layer 3 in the direction of chip center line C on the outer periphery of the intermediate part 2C L Embedded in the mounting hole 17 in the hard layer on the outer periphery of the intermediate part 2C The width in the direction of the chip center line C of the portion that is not present S The width in the direction of the chip center line C of the portion buried in the mounting hole 17 in the hard layer on the outer periphery of the intermediate portion 2C

Claims (7)

A drilling tip attached to the tip of the drilling bit for drilling,
A chip body and a hard layer made of a diamond sintered body harder than the chip body covering the chip body,
The chip body has a rear end portion that has a columnar shape or a disk shape with the chip center line as the center, and an outer diameter that is larger than the rear end portion that is located on the front end side in the chip center line direction with respect to the rear end portion. A small intermediate portion, and a distal end portion that is located on the distal end side in the tip center line direction with respect to the intermediate portion and gradually decreases in outer diameter from the tip center line toward the distal end side,
The hard layer is coated from the tip surface of the chip body to the outer periphery of the intermediate part, and the outer diameter of the hard layer in the intermediate part is made equal to the outer diameter of the rear end part of the chip body. A drilling tip characterized by The excavation tip according to claim 1, wherein the intermediate portion has a columnar shape or a disc shape centering on the tip center line having a smaller outer diameter than the rear end portion. The excavation tip according to claim 1 or 2, wherein the hard layer coated on the outer periphery of the intermediate portion has a width in the tip center line direction within a range of 1 mm to 5 mm. The excavation tip according to any one of claims 1 to 3, wherein a thickness of the hard layer coated on an outer periphery of the intermediate portion is in a range of 300 µm to 1200 µm. The excavation tip according to any one of claims 1 to 4 is a excavation bit attached to a tip portion of a bit body,
A mounting hole is formed at the tip of the bit body,
The excavation tip is attached by burying the rear end portion of the tip body and at least a part of the intermediate portion covered with the hard layer in the attachment hole. Drilling bit. 6. The excavation according to claim 5, wherein a width of the portion buried in the mounting hole in the hard layer covered with the intermediate portion in a direction of the tip center line is 0.5 mm to 4.5 mm. bit. 6. The width in the tip center line direction of a portion of the hard layer covered by the intermediate portion that is not buried in the mounting hole is 0.5 mm to 1.0 mm. Item 7. The excavation bit according to item 6.

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