JPS5858517B2 - wing bit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wing bit, and particularly to a wing bit suitable for rock excavation such as an underground continuous wall excavation method or a large diameter driving pile excavation method.

For example, in the underground continuous wall excavation method, multi-axis (for example, 5
A wing bit (shaft) is used, and the cutting edge of the wing bit is conventionally constructed by planting a cemented carbide tip, and the hardness and properties of the cemented carbide tip enable drilling of complex geological formations.

However, underground continuous wall excavators have a structure that excavates the front layer by applying bit supply pressure (a thrust load in the excavation direction that acts on the excavation surface of the bit) using the machine's own weight. Due to the relationship between the number of implanted chips and the wear width, for rocks with a compressive strength of 500/4/crtr per axis of a multi-axis wing bit, the wear surface will expand when the wear width of the tips becomes about one barrel. This results in poor cutting ability (making it difficult to dig even under the total load), and wing bits using conventional cemented carbide tips no longer function as medium-hard drilling bits and have poor wear resistance. The drawback is that drilling efficiency is low.

The present invention provides a wing bit with little wear on the cutting edge, no change in sharpness due to wear, and no need to increase the bit supply pressure, and a drilling surface with excellent impact resistance. The present invention provides a wing bit that can efficiently excavate hard rock.

Conventional cutting edge materials for geological excavation include Gyoten steel, cemented carbide, and Diamondsend, each with its own advantages and benefits.
They have disadvantages and are used as appropriate.

However, in methods such as underground continuous wall excavation method and large diameter driven pile excavation method, in which rock excavation is performed by lowering the bit supply pressure due to the weight of the excavating machine, the conventional Wing bits with a structure in which diamond particles are embedded, such as the surface grain set type or the impregnated type, have not been able to be put into practical use.

That is, since diamond is weak against impact, it has been extremely difficult to use it in the above-mentioned drilling method in which the circumferential speed due to rotation is considerably high.

The present invention eliminates the drawbacks of the conventional technology and uses a cylindrical tip in which an edge edge made of polycrystalline diamond or boron nitride is formed on the surface layer of cemented carbide, and the implantation is performed at an angle (rake angle). By giving a continuous angle increase (increase in rake angle) from the inner diameter to the outer diameter, the aim is to provide a wing bit that is highly efficient and suitable for hard rock excavation. do.

That is, according to the present invention, a plurality of blades extending substantially radially with respect to the rotating shaft are fixed, and a plurality of chips are fixed to each blade on the excavation surface so that the entire cross section is excavated. A wing bit is provided, characterized in that the tip is composed of a cylindrical tip whose end face is a blade, and the rake angle of each tip is selected to be larger closer to the outer periphery.

According to this configuration of the present invention, conventional wing bits with tips made of cemented carbide suffer from wear and can only be used on soft rocks, and each bit has a limitation in supply pressure. Improved wear resistance and bit feed pressure without increasing the bit feed pressure (less wear, or even if wear occurs, the self-sharpening effect does not reduce sharpness, so there is no need to increase the bit feed pressure) ) A wing bit is provided that can efficiently excavate medium-hard rock and hard rock.

On the other hand, as mentioned above, impact resistance can be improved by providing a rake angle on each chip and increasing this rake angle closer to the outer periphery where the tangential velocity is higher. Coupled with this, even more efficient hard rock excavation can be achieved.

In this case, the rake angle of the tip is about 15 degrees to about 3 degrees.
A range of 0 nights is appropriate.

Furthermore, by creating a structure in which the excavated surface of the blade is inclined upward in the radial direction, and the degree of inclination becomes greater as it approaches the outer periphery, the chips can be planted in a higher density at the outer periphery where the tangential velocity is higher. As a whole, it can provide wing bits with the right balance of sharpness.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 and 2, in the embodiment of the wing bit of the present invention, a plurality of (four in the illustrated example) blade members 2 extend approximately radially with respect to the rotating shaft 1. Fixed.

The rotating shaft 1 and the blade member 2 are each made of steel and fixed to each other by welding or the like.

For each blade member 2, a tooth 3 is attached to a bolt 4.
It is removably fixed.

A plurality of chips 6 are planted along the radial direction on the excavation surface 5 of each tooth 3.

The blades of the wing bit are constituted by the blade member 2 and the teeth 3, and the arrangement of the chips 6 planted in each tool 3 is such that when the wing bit rotates, the blades of the wing bit as a whole are aligned with the bedrock in the entire cross section of the bit. etc. are arranged to excavate.

That is, when the bit rotates, at least one tip 6 is arranged so as to cut at any radius from the center to the outer circumference so that no excavation remains in a certain radius.

As shown in FIGS. 1 to 3 (see especially FIG. 3), each chip 6 has a cylindrical shape as a whole, and a blade (cutting blade) 8 is silver-brazed to the end surface of a cylindrical base material 7. It is constructed by joining.

In normal cases, the base material I is made of, for example, a wc-Co cemented carbide sintered body, and the blade is made of diamond, boron nitride, or the like sintered with a binder.

As shown in FIG. 3, the teeth 3 of each chip
The implantation and fixation to the base plate is performed with a predetermined rake angle θ.

The appropriate value of this rake angle θ is, for example, in the range of about 15 degrees to 30 degrees, and the closer the blade (tooth 3) is implanted to the outer periphery, the larger the rake angle is selected.

This rake angle is intended to improve impact resistance during excavation, and the rake angle θ is
is made large enough to sufficiently buffer the impact load.

In addition, as shown in FIG. 2, the excavated surface 5 of the blade (tooth 3)
is slanted radially outward and upward, and in the example shown,
The portion near the inner periphery has an inclination of approximately 30 degrees at an angle α, and the portion near the outer periphery has an inclination Ω at an angle β of approximately 45 degrees.

The reason why the cutting surface 5 is provided with an inclination is to realize full cross-sectional excavation in which the chips 6 are sufficiently distributed at a high density with respect to the cross section in the cutting direction.

If it is not necessary to arrange the chips at a very high density due to cutting conditions, etc., it is possible to omit the slope.

Moreover, the reason why the slope of the excavation surface 5 is increased toward the outer periphery is as follows.
This is because the tangential speed during excavation is higher at the outer circumference, so the chips 6 are arranged at a higher density than at the inner circumference so that a well-balanced cutting quality can be achieved as a whole.

In the illustrated example, the cut surface 5 has two inclinations α and β.
Although a stepped inclination is provided, it is also possible to provide a stepless incline such that the degree of inclination is continuously changed and the degree of upward inclination increases toward the outer periphery.

In the illustrated embodiment, the blade is composed of a blade member 2 and a tooth 3, and the tooth is removably (replaceably) fixed with a bolt 4. Therefore, when the tip 6 is worn out due to excavation, only the tooth 30 portion is used. Since the excavation work can be continued by replacing the excavation work, the efficiency of the excavation work can be improved.

Diamond particles 10 are planted on the outer circumferential gauge surface of the blade, that is, on the outer circumferential surface of the teeth 3 in the illustrated example.

The diamond particles 10 can be planted, for example, by embedding the diamond particles in a sintered body of cemented carbide.

By planting diamond particles on the outer circumferential gauge surface in this manner, the wear resistance of the gauge surface, that is, the portion that forms the inner diameter of the borehole can be increased.

According to the embodiment described above, the following effects can be achieved.

Since each tip that makes up the cutting blade uses a cylindrical tip with diamonds etc. fixed on the end face, even if it wears out, the edge will always remain and a so-called self-sharpening effect can be obtained, so the sharpness will remain sharp even after long drilling. The effect is that it does not change.

Further, since a cylindrical tip is used, wear of the cutting edge can be reduced compared to a conventional tip having a triangular chevron-shaped cutting edge or a protruding semicircular cutting edge.

In addition, each tip is provided with a rake angle, and the rake angle is selected to be larger as it approaches the outer periphery, so that a wing bit with sufficient strength against the impact load particularly when excavating hard rock at a predetermined speed can be obtained.

That is, by providing a predetermined rake angle, it is possible to buffer the impact load applied to the cutting edge.

In addition, the excavation surface 5 formed on the lower surface of each blade is sloped outward and upward in the radial direction, and the degree of inclination is increased closer to the outer circumference, so that the tip 6 constituting the excavation blade can be adjusted to the tangential speed during excavation. They can be arranged at a correspondingly high density and can therefore be efficiently excavated even in hard rock, achieving a significant improvement in excavation performance.

Furthermore, since the tooth 3 with the tip 6 planted thereon is removably fixed, it is possible to efficiently replace the tip when it wears out.

Furthermore, since diamond particles are planted on the gauge surface of the outer periphery of the blade (the outer periphery of the teeth 3), the wear resistance of the gauge surface can be improved, thereby improving the accuracy of drilling holes and improving drilling performance. It can also be achieved.

Conventionally, hardened steel tooth type bits have poor wear resistance in practical use, and the conventionally widely used wing bits with cemented carbide tips have difficulty drilling due to the relationship between the wear of the carbide tips and the bit load. There were restrictions on rock quality.

However, according to the above-mentioned embodiment of the wing bit according to the present invention, when an actual excavation test was conducted on andesite (hardness Hs 75 + - axial compression strength 800~, d), it was found that the conventional cemented carbide wing bit It is possible to excavate rock types that were previously impossible to excavate, and the wing is equipped with 32 cemented carbide chips with a polycrystalline diamond layer at 50 rpm and a self-weight of 1.0 to 2.5 tons per bit. Places excavated using a bit 4-13/? It was possible to excavate 772/rrR.

In other words, high excavation performance that could not be obtained with the conventional technology was obtained.

In addition, when drilling with a bit size of 400 mm in diameter, by planting a 1730 carat diamond sintered piece on the outer gauge surface, the gauge can be secured and wear on the outer gauge surface can be reduced. I was able to do it.

Furthermore, as in the above-mentioned embodiment (as the radially outward upward angle of the bit on the outer circumferential side and the inner circumferential side of the excavation surface, the outer circumferential side is 45
By increasing the planting density of the blades (chips) and making the inner periphery approximately 30 degrees, the impact load on each bit blade (chip) is made uniform, and this is reduced to strengthen the bit blades. was able to be carried out.

As is clear from the above description, according to the present invention, a wing bit can be obtained that can exhibit excellent excavation performance and durability even on hard rock.

[Brief explanation of the drawing]

FIG. 1 is a bottom view of an embodiment of the wing bit of the present invention;
2 is a partial cross-sectional view taken along the line ■--■ in FIG. 1, and FIG. 3 is a partial cross-sectional view taken along the line ■--■ in FIG. 1...Rotating shaft, 2...Blade member, 3.
...Tooth, 5...Cutting surface, 6...
...Chip, T...Base material, 8...Chip blade, 9...Outer gauge surface, 10...
・Diamond particles, θ...rake angle, α, β
...Radially outward and upward angle of the excavation surface.

Claims (1)

[Claims] 1. A plurality of blades extending substantially radially to the rotating shaft are fixed, and a plurality of chips are fixed to each blade on the excavation surface so that the entire cross section is excavated. A wing bit consists of a cylindrical tip with a blade on the end surface, and the rake angle of each tip is selected to be larger closer to the outer periphery. 2. The wing bit according to claim 1, wherein the tip has a rake angle in a range of about 15 degrees to about 30 degrees. 3. The excavated surface of the blade is inclined radially outward and upward;
The wing bit according to claim 1 or 2, characterized in that the closer to the outer periphery, the greater the degree of inclination of the wing bit. 4. The wing bit according to any one of claims 1 to 3, wherein the blade is constructed by fixing a tip to a tooth and removably fixing the tooth to a blade member. . 5. The wing bit according to any one of claims 1 to 4, characterized in that diamond particles are planted in the outer circumferential gauge of the blade. 6. The wing bit according to any one of claims 1 to 5, wherein the blade of the tip is made of polycrystalline diamond or boron nitride.