Tunnel boring machine and method for manufacturing a tunnel boring machine

Abstract

The present invention provides a tunnel boring machine and a method for manufacturing a tunnel boring machine that can suppress the chipping and wear of cutting bits during excavation. [Solution] This tunnel boring machine 100 includes a cutting bit 1a which includes a hard tip 11a and a shank 12a to which the hard tip 11a is joined, and a cutter head 1 on which the cutting bit 1a is installed, and at least one of the outer surface of the hard tip 11a and the outer surface of the shank 12a is provided with a surface hardening layer 111a (112a) which has been modified to have a high hardness.

Description

Technical Field

[0001] The present invention relates to a tunnel boring machine and a method for manufacturing a tunnel boring machine, and particularly to a tunnel boring machine including cutting bits and a method for manufacturing a tunnel boring machine.

Background Art

[0002] Conventionally, a tunnel boring machine equipped with cutting bits has been known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a shield tunneling machine (tunnel boring machine) including a cutting bit including a base material (shank) and a plurality of hard tips fixed to the base material in a state protruding in the tunneling direction from the base material, and a cutter head on which the cutting bit is installed. In Patent Document 1, by arranging the hard tip located on the outermost side in the rotational direction of the cutter head inside the base materials located at both ends in the rotational direction of the cutter head, the hard tip is sandwiched between soft base materials, suppressing the loss of the hard tip.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the cutting bit of Patent Document 1, since the shank, which is softer than the hard tip, is located on the outer side in the rotational direction, the shank may also come into contact with relatively hard rock during tunneling and suffer from loss and wear, just like the hard tip. Therefore, there is a need for a tunnel boring machine and a method for manufacturing a tunnel boring machine that can suppress the loss and wear of the cutting bit during tunneling.

[0006] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide a tunnel boring machine and a method for manufacturing a tunnel boring machine that can suppress chipping and wear of the cutting bit during excavation. [Means for solving the problem]

[0007] To achieve the above objective, the tunnel boring machine of this invention comprises a cutting bit including a hard tip and a shank to which the hard tip is joined, and a cutter head on which the cutting bit is installed, wherein at least one of the outer surface of the hard tip and the outer surface of the shank is provided with a surface hardening layer that modifies the surface to a high hardness, including an uneven surface formed from a plurality of fine recesses.

[0008] In the tunnel boring machine of this invention, as described above, at least one of the outer surfaces of the hard tip and the shank is provided with a surface hardening layer that includes an uneven surface formed from a plurality of fine recesses, thereby modifying the surface to a high hardness. As a result, at least one of the outer surfaces of the hard tip and the shank is modified to a high hardness, thereby improving the strength of the cutting bit. Consequently, chipping and wear of the cutting bit during excavation can be suppressed. Furthermore, by providing recesses, the contact area with excavated soil is reduced, and lubricants injected to improve groundwater and excavated soil are held in the recesses, thereby suppressing soil adhesion to the surface of the cutting bit, and reducing excavation resistance and excavation vibration.

[0009] In the tunnel boring machine of this invention, preferably, the outer surface of the hard tip is provided with a surface hardening layer containing fine recesses having a diameter of less than 100 μm. This configuration improves the hardness of the hard tip, and thus further improves its hardness. Furthermore, because the diameter of the fine recesses is less than 100 μm, multiple fine recesses can be provided, and when processing to create multiple fine recesses, more impact is applied to the outer surface of the hard tip, further improving the hardness of the outer surface of the hard tip. In addition, by providing fine recesses, a film can be formed on the surface of the recesses by the moisture contained in the soil, thereby suppressing the adhesion of soil to the surface of the hard tip.

[0010] In this case, preferably, both the outer surface of the hard tip and the outer surface of the shank are provided with a surface hardening layer including recesses, and the diameter of the recesses on the outer surface of the shank is at least twice as large as the diameter of the recesses on the outer surface of the hard tip. With this configuration, by reducing the size of the recesses on the outer surface of the hard tip, it is possible to form a fine uneven surface while improving the hardness of the hard tip without damaging the hard tip, and by increasing the size of the recesses on the outer surface of the shank, it is possible to increase the thickness of the surface hardening layer on the outer surface of the shank and greatly improve the hardness of the shank. Furthermore, since the hardness of both the outer surface of the hard tip and the outer surface of the shank can be improved, the strength of the cutting bit can be further improved. As a result, chipping and wear of the cutting bit during excavation can be further suppressed. In addition, the contact area with excavated soil is reduced, and lubricants injected to improve groundwater and excavated soil are held in the recesses, which suppresses soil from adhering to the surface of the cutting bit, thereby reducing excavation resistance and excavation vibration.

[0011] In the tunnel boring machine of this invention, preferably, the outer surface of the shank is provided with a surface hardening layer and a lubricant discharge port positioned in the region where the surface hardening layer is provided, for discharging lubricant. With this configuration, lubricant can be supplied to the surface hardening layer of the shank, so that the lubricant accumulates directly in the recesses, reducing the frictional resistance between the surface hardening layer of the shank and the soil, and suppressing the accumulation of soil in the recesses. As a result, it is possible to suppress the generation of vibrations due to frictional resistance between the shank and the soil during excavation, while also suppressing the accumulation of soil on the cutter head.

[0012] In this case, preferably, the uneven surface provided on the outer surface of the shank includes a first uneven surface formed from a plurality of fine first recesses and a second uneven surface formed from second recesses having a diameter five times or more that of the first recesses, with the first and second uneven surfaces overlapping. With this configuration, the first uneven surface formed from a plurality of fine first recesses is formed on the second uneven surface formed from second recesses having a diameter five times or more that of the first recesses, thereby reducing the contact area between fine soil particles contained in the first recesses and larger soil particles, suppressing the adhesion of soil to the surface of the cutting bit, and achieving a reduction in excavation resistance and excavation vibration.

[0013] The present invention relates to a method for manufacturing a tunnel boring machine, comprising a cutting bit including a hard tip, a shank to which the hard tip is joined, and a cutter head on which the cutting bit is installed, and comprising at least one of the following steps: spraying first fine particles onto the outer surface of the hard tip to form an uneven surface including recesses and simultaneously form a surface hardened layer that modifies the surface to a high hardness; and spraying second fine particles onto the shank to form an uneven surface including recesses and simultaneously form a surface hardened layer that modifies the surface to a high hardness.

[0014] As described above, the manufacturing method of the tunnel boring machine of this invention comprises at least one of the following steps: spraying first fine particles onto the outer surface of a hard tip to form an uneven surface including recesses and simultaneously form a surface hardened layer that modifies the surface to a high hardness; and spraying second fine particles onto the shank to form an uneven surface including recesses and simultaneously form a surface hardened layer that modifies the surface to a high hardness. As a result, at least one of the outer surface of the hard tip and the outer surface of the shank can have its outer surface hardness modified to a high hardness by spraying the first or second fine particles, thereby enabling the manufacture of a cutting bit with improved strength. As a result, a tunnel boring machine that can suppress chipping and wear of the cutting bit during excavation can be manufactured. Furthermore, by providing recesses, the contact area with excavated soil is reduced, and lubricants injected to improve groundwater and excavated soil are held in the recesses, thereby suppressing soil adhesion to the surface of the cutting bit, and enabling the manufacture of a tunnel boring machine that reduces excavation resistance and excavation vibration.

[0015] In the manufacturing method of the tunnel boring machine of this invention, preferably, the step of forming a surface hardening layer on the outer surface of the hard chip includes a step of spraying first fine particles having a diameter of less than 100 μm onto the outer surface of the hard chip to form an uneven surface including fine recesses having a diameter of less than 100 μm, while simultaneously forming a surface hardening layer. With this configuration, a surface hardening layer can be formed on the outer surface of the hard chip, making it possible to manufacture a hard chip with improved hardness. Furthermore, by spraying first fine particles having a diameter of less than 100 μm onto the outer surface of the hard chip to form an uneven surface including fine recesses having a diameter of less than 100 μm, the hardness of the outer surface of the hard chip can be improved by the impact of the sprayed first fine particles, while an uneven surface including recesses can be easily formed. In addition, by providing fine recesses, the contact area with excavated soil is reduced, and furthermore, groundwater and lubricants injected to improve the excavated soil are held in the recesses, making it possible to manufacture a tunnel boring machine that can suppress the adhesion of soil to the hard chip.

[0016] In this case, preferably, the process includes the steps of providing a surface hardening layer on the outer surface of the hard tip and providing a surface hardening layer on the outer surface of the shank. The step of providing a surface hardening layer on the outer surface of the shank includes spraying second fine particles having a diameter at least twice as large as the first fine particles onto the outer surface of the shank to form an uneven surface including recesses having a diameter at least twice as large as the diameter of the recesses provided in the hard tip, while simultaneously forming a surface hardening layer that modifies the surface to a high hardness. With this configuration, by providing a step of providing a surface hardening layer on both the outer surface of the hard tip and the outer surface of the shank, the hardness of the hard tip and the shank can be improved, thereby further improving the strength of the cutting bit. As a result, it is possible to manufacture a tunnel boring machine that further suppresses chipping and wear of the cutting bit during excavation. In addition, by reducing the contact area with excavated soil and retaining lubricants injected to improve groundwater and excavated soil in the recesses, it is possible to manufacture a tunnel boring machine that suppresses soil adhesion to the surface of the cutting bit, thereby reducing excavation resistance and excavation vibration.

[0017] The manufacturing method of the tunnel boring machine of this invention preferably includes at least a step of forming a surface hardening layer on the outer surface of the shank, the step of forming a surface hardening layer on the outer surface of the shank including a first uneven surface including a first recess by spraying fine particles, and a step of forming a second uneven surface including a second recess having a diameter five times or more larger than the first recess by spraying particles having a diameter five times or more larger than the fine particles, thereby overlapping the first uneven surface and the second uneven surface. With this configuration, both the step of spraying small fine particles to form the first recess and the step of spraying large particles to form the second recess are performed in reverse order, and a composite structure composed of a fine first uneven surface formed from the first recess and a second uneven surface formed from the second recess is formed, thereby enabling the manufacture of a tunnel boring machine that can effectively reduce the contact area with soil composed of different soil particles, from fine soil particles to large soil particles, suppress the adhesion of soil to the surface of the cutting bit, and reduce excavation resistance and excavation vibration. [Effects of the Invention]

[0018] According to the present invention, as described above, it is possible to provide a tunnel boring machine and a method for manufacturing a tunnel boring machine that can suppress the loss and wear of a cutting bit during excavation.

Brief Description of the Drawings

[0019] [Figure 1] It is a cross-sectional view showing the tunnel boring machine according to the first embodiment from the side. [Figure 2] It is a partially enlarged view of the spoke according to the first embodiment. [Figure 3] It is a cross-sectional view taken along line III-III of FIG. 2. [Figure 4] It is a cross-sectional view of the surface hardened layer provided on the hard tip according to the first embodiment. [Figure 5] It is a cross-sectional view of the surface hardened layer provided on the shank according to the first embodiment. [Figure 6] It is a flowchart of the method for manufacturing a tunnel boring machine according to the first embodiment. [Figure 7] It is a view showing a shank provided with a concavo-convex surface according to the second embodiment. [Figure 8] It is a cross-sectional view of the surface hardened layer provided on the shank according to the second embodiment. [Figure 9] It is a flowchart of the step of providing a surface hardened layer on the outer surface of the shank according to the second embodiment.

Modes for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0021] [First Embodiment] (Configuration of Tunnel Boring Machine) Referring to FIGS. 1 to 6, the tunnel boring machine 100 according to the first embodiment will be described.

[0022] In each figure, the direction parallel to the rotational axis α of the cutter head 1, which extends along the excavation direction (forward-backward direction), is indicated by the X direction. Of the X directions, the excavation direction (forward) is indicated by the X1 direction, and the other direction (rearward) is indicated by the X2 direction. Note that the rotational axis α is also the central axis of the body 3.

[0023] In each diagram, the vertical direction is indicated by the Z direction. Within the Z direction, the upward direction is indicated by Z1, and the downward direction is indicated by Z2. Also, the left-right direction when looking from X1 to X2 is indicated by the Y direction. Within the Y direction, the left side is indicated by Y1, and the right side is indicated by Y2.

[0024] As shown in Figure 1, the tunnel boring machine 100 includes a cutter head 1 and a boring machine body 2 including a shell 3. The tunnel boring machine 100 is, for example, a mud pressure type tunnel boring machine 100.

[0025] (Cutter head configuration) The cutter head 1 includes a spoke 1b, a plurality of cutting bits 1a provided on the side of the spoke 1b, and a plurality of cutting bits 1a' provided on the front of the spoke 1b. The plurality of cutting bits 1a, 1a' are configured to excavate the ground by the rotation of the cutter head 1.

[0026] The spokes 1b are located on the front surface of the cutter head 1 and are arranged radially around the rotational axis α. Specifically, the spokes 1b extend in a direction perpendicular to the X direction. Each of the spokes 1b is provided with multiple cutting bits 1a, 1a'.

[0027] As shown in Figure 2, in the case of a spoke 1b extending in the Z direction, when viewed from the front (X1 direction), shanks 12a are attached to the left side (Y1 direction) and the right side (Y2 direction) using the side surfaces (Y direction). The hard tip 11a is attached to the front surface of the shank 12a. The hard tip 11a is located on the opposite side of the shank 12a from the side that connects to the spoke 1b. For the shank 12a in the Y1 direction, the hard tip 11a is attached to the Y1 direction end of the front surface of the shank 12a. Similarly, for the shank 12a in the Y2 direction, the hard tip 11a is attached to the Y2 direction end of the front surface of the shank 12a. Details of the hard tip 11a and shank 12a will be described later.

[0028] As shown in Figure 1, the cutter head 1 is supported from the rear by a plurality of support legs 1c. The support legs 1c are fixed to the front surface of an annular support ring 1d.

[0029] (Excavator body configuration) The excavator body 2 includes a cylindrical shell 3, a plurality of propulsion hydraulic jacks 4, a bulkhead 5, a screw conveyor 6, a slewing platform bearing 7, and a drive source 8.

[0030] The body section 3 is located behind the cutter head 1. The body section 3 includes a front body section located in the X1 direction and a rear body section located in the X2 direction. The cutter head 1 is installed at the front tip of the front body section in the direction of excavation. Inside the front body section are multiple propulsion hydraulic jacks 4, a screw conveyor 6, a slewing platform bearing 7, and a drive source 8. A partition wall 5 is also provided inside the front body section. The body section 3 consists of a front body section and a rear body section. The rear body section is the part that advances as the tunnel boring machine 100 excavates, arranging segments SG on the wall surface using erectors (not shown) to form the perimeter wall of the tunnel. The internal space of the body section 3 is divided into two spaces by the partition wall 5: a chamber C on the excavation direction side and a working space behind the chamber C.

[0031] Multiple propulsion hydraulic jacks 4 are arranged at predetermined angular intervals in the direction of rotation (RO direction) of the cutter head 1. The multiple propulsion hydraulic jacks 4 are fixed to the body 3 and are configured to push the excavator body 2 forward. In other words, the multiple propulsion hydraulic jacks 4 are the drive unit that propels the excavator body 2.

[0032] The partition wall 5 extends in a direction perpendicular to the excavation direction (X1 direction) and separates the chamber C, where the soil excavated by the cutter head 1 is stored, from the space behind chamber C.

[0033] The screw conveyor 6 is connected to the chamber C and is configured to discharge the soil and sand inside the chamber C into the space behind the bulkhead 5. The screw conveyor 6 is located on the lower side of the inside of the front section of the fuselage.

[0034] The slewing bearing 7 is configured to transmit the rotational force of the drive source 8 to the cutter head 1. The slewing bearing 7 includes an annular fixed outer ring 70 fixed to the front body and an annular movable inner ring 71 positioned on the inner circumference side of the fixed outer ring 70. The movable inner ring 71 has an annular internal gear (rack) that meshes with the pinion gear of the drive source 8. The movable inner ring 71 is fixed to the rear surface of the annular support ring 1d.

[0035] (Detailed structure of the cutting bit) As shown in Figures 2 and 3, each cutting bit 1a includes a hard tip 11a, a shank 12a, and a lubricant discharge port 13a.

[0036] The hard tip 11a includes a blade for excavating rock, soil, etc. The hard tip 11a is formed, for example, by mixing tungsten carbide powder and cobalt powder. The tungsten carbide powder has relatively high hardness and constitutes the blade for excavation. The cobalt powder is configured to function as a binder for the tungsten carbide powder.

[0037] The hard tip 11a has a rake face and a flank face. The side of the hard tip 11a opposite the flank face and the side opposite the rake face are the surfaces that join to the shank 12a. A surface hardening layer 111a is provided on the outer surface of the hard tip 11a. The surface hardening layer 111a is provided on all surfaces of the outer surface of the hard tip 11a except for the surfaces that join to the shank 12a.

[0038] As shown in Figures 2 and 4, the surface hardened layer 111a includes a surface uneven surface 1111a (hard tip side uneven surface) formed from a plurality of fine recesses 111b having a diameter of less than 100 μm and protrusions 111c located between the recesses 111b. The diameters of the plurality of fine recesses 111b may all be the same, or at least some may be different. The hard tip 11a is modified to a high hardness by forming recesses 111b in the surface hardened layer 111a.

[0039] The surface hardening layer 111a of the hard chip 11a is formed by spraying first fine particles onto the outer surface of the hard chip 11a. The first fine particles have a diameter of less than 100 μm. The formation of the surface hardening layer 111a occurs simultaneously with the formation of fine recesses 111b on the outer surface of the hard chip 11a. The surface hardening layer 111a is formed by impacting the surface of the hard chip 11a with fine particles. For example, WPC treatment (registered trademark), a type of shot peening, is used to form the surface hardening layer 111a. In the hard chip 11a on which the surface hardening layer 111a is formed, the toughness is improved and the hardness is increased. As a result, the durability of the hard chip 11a is improved.

[0040] As shown in Figure 2, the shank 12a is configured to fix the hard tip 11a to the spoke 1b. The shank 12a is made of carbon steel. The hard tip 11a is joined to the shank 12a by brazing. The shank 12a is joined to the spoke 1b on the side opposite to the side to which the hard tip 11a is joined.

[0041] As shown in Figures 2 and 5, a surface hardening layer 112a is provided on the outer surface of the shank 12a. The surface hardening layer 112a is provided on all surfaces of the outer surface of the shank 12a except for the surface to which the hard tip 11a is attached. The surface hardening layer 112a includes an uneven surface 1112a (shank-side uneven surface) formed from recesses 112b and protrusions 112c located between the recesses 112b. The diameter of the recesses 112b provided on the outer surface of the shank 12a is larger than the diameter of the recesses 111b provided on the outer surface of the hard tip 11a, for example, twice as large (100 μm) or more. The diameters of the multiple recesses 112b may all be the same, or at least some may be different. Furthermore, the diameter of some of the multiple recesses 112b may be larger than the diameter of the recesses 111b provided on the outer surface of the hard tip 11a, and the diameter of all of the multiple recesses 112b may be larger than the diameter of the recesses 111b provided on the outer surface of the hard tip 11a.

[0042] The surface hardened layer 112a of the shank 12a is formed by spraying second fine particles having a larger diameter than first fine particles onto the outer surface of the shank 12a. The second fine particles have a diameter of, for example, twice (200 μm) or more. The formation of the surface hardened layer 112a occurs simultaneously with the formation of the recess 112b on the outer surface of the shank 12a. Shot peening, for example, is used to form the surface hardened layer 112a. In the shank 12a on which the surface hardened layer 112a is formed, the toughness is improved and the hardness is increased. As a result, the durability of the shank 12a is improved. Furthermore, since the diameter of the recess 112b of the shank 12a is larger than the diameter of the recess 111b of the hard tip 11a, by reducing the size of the recess 111b provided on the outer surface of the hard tip 11a, it is possible to form a fine uneven surface 1111a while improving the hardness of the hard tip 11a without damaging the hard tip 11a. On the other hand, by increasing the size of the recess 112b provided on the outer surface of the shank 12a, it is possible to increase the thickness of the surface hardened layer 112a provided on the outer surface of the shank 12a while significantly improving the hardness of the shank 12a.

[0043] As shown in Figure 3, a lubricant discharge port 13a is provided on the outer surface of the shank 12a. The lubricant discharge port 13a is located in the region where the surface hardening layer 112a of the shank 12a is provided. Specifically, the lubricant discharge port 13a is located on the front surface of the shank 12a where the surface hardening layer 112a is provided. Furthermore, the lubricant discharge port 13a is located in the central part of the front surface of the shank 12a, and a recess 112b is provided on the front surface of the shank 12a so as to surround the lubricant discharge port 13a. The lubricant discharge port 13a is configured to discharge lubricant containing lubricating oil stored in a tank (not shown) to the outer surface of the shank 12a. Inside the shank 12a, there is a flow path through which the lubricant flows, as well as a flow path connecting the lubricant discharge port 13a and the tank. The arrow in Figure 3 indicates the direction in which the lubricant flows from the tank into the flow path. The supplied lubricant accumulates in the recess 112b of the shank 12a, reducing frictional resistance between the shank 12a and the soil. The lubricant also prevents soil from adhering to the shank 12a and forming large clumps of soil.

[0044] (Manufacturing method for tunnel boring machines) A method for manufacturing the tunnel boring machine 100 will be described based on Figure 6. First, as step S1, a process is performed to form a surface hardened layer 111a on the outer surface of the hard chip 11a. Specifically, the process of forming a surface hardened layer 111a on the outer surface of the hard chip 11a includes a step of spraying first fine particles having a diameter of less than 100 μm onto the outer surface of the hard chip 11a to form fine recesses 111b having a diameter of less than 100 μm and simultaneously form the surface hardened layer 111a. When the first fine particles collide, fine recesses 111b having a diameter of less than 100 μm are formed in the cobalt binder layer of the hard chip 11a, and at the same time, the surface hardened layer 111a is formed by the impact caused by the collision of the first fine particles.

[0045] Step S2 involves forming a surface hardened layer 112a on the outer surface of the shank 12a. Specifically, the step of forming a surface hardened layer 112a on the outer surface of the shank 12a includes spraying second fine particles having a diameter at least twice that of the first fine particles onto the outer surface of the shank 12a to form a recess 112b having a diameter at least twice that of the recess 111b provided in the hard tip 11a, and simultaneously forming a surface hardened layer 112a with a modified surface hardness. The diameter of the second fine particles is, for example, 200 μm or more. The recess 112b is formed when the second fine particles collide with the shank 12a, and at the same time, the surface hardened layer 112a is formed by the impact caused by the collision of the second fine particles.

[0046] After steps S1 and S2 are performed, the hard tip 11a, on which the surface hardened layer 111a is formed, and the shank 12a, on which the surface hardened layer 112a is formed, are brazed together. This forms the cutting bit 1a. The completed cutting bit 1a is attached to the spoke 1b to form the cutter head 1. Then, the cutter head 1 and the excavator body 2 are combined to manufacture the tunnel boring machine 100.

[0047] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0048] In the first embodiment, as described above, at least one of the outer surfaces of the hard tip 11a and the shank 12a is provided with a surface hardening layer 111a (112a) that includes a recess 111b (112b) and has been modified to have high hardness. As a result, at least one of the outer surfaces of the hard tip 11a and the shank 12a is modified to have high hardness, thereby improving the strength of the cutting bit 1a. As a result, damage to the cutting bit 1a during excavation can be suppressed. Furthermore, by providing the recess 111b (112b), the contact area with excavated soil is reduced, and the lubricant injected to improve groundwater and excavated soil is held in the recess 111b (112b), thereby suppressing soil from adhering to the surface of the cutting bit 1a, and reducing excavation resistance and excavation vibration.

[0049] Furthermore, in the first embodiment, as described above, the outer surface of the hard chip 11a is provided with a surface hardening layer 111a including fine recesses 111b having a diameter of less than 100 μm. This improves the hardness of the hard chip 11a, and thus further improves its hardness. Also, because the diameter of the fine recesses 111b is less than 100 μm, multiple fine recesses 111b can be provided, so when processing to provide multiple fine recesses 111b, more impact is applied to the outer surface of the hard chip 11a, further improving the hardness of the outer surface of the hard chip 11a. In addition, by providing fine recesses 111b, a film can be formed on the surface of the recesses 111b by the moisture contained in the soil, thus suppressing the adhesion of soil to the surface of the hard chip 11a.

[0050] Furthermore, in the first embodiment, as described above, both the outer surface of the hard tip 11a and the outer surface of the shank 12a are provided with a surface hardening layer 111a (112a) including recesses 111b (112b), and the diameter of the recess 112b provided on the outer surface of the shank 12a is twice as large as the diameter of the recess 111b provided on the outer surface of the hard tip 11a. This makes it possible to form a fine uneven surface 1111a while improving the hardness of the hard tip 11a without damaging the hard tip 11a by making the recess 111b provided on the outer surface of the hard tip 11a smaller, and to significantly improve the hardness of the shank 12a while increasing the thickness of the surface hardening layer 112a provided on the outer surface of the shank 12a by making the recess 112b provided on the outer surface of the shank 12a larger. In addition, since the hardness of both the outer surface of the hard tip 11a and the outer surface of the shank 12a can be improved, the strength of the cutting bit 1a can be further improved. As a result, chipping and wear of the cutting bit 1a during excavation can be further suppressed. Furthermore, the contact area with the excavated soil is reduced, and the lubricant injected to improve groundwater and excavated soil is retained in the recess 111b (112b), thereby suppressing soil adhesion to the surface of the cutting bit 1a, and reducing excavation resistance and excavation vibration.

[0051] Furthermore, in the first embodiment, as described above, the outer surface of the shank 12a is provided with a surface hardening layer 112a and a lubricant discharge port 13a positioned in the region where the surface hardening layer 112a is provided, for discharging lubricant. This allows lubricant to be supplied to the surface hardening layer 112a of the shank 12a, causing lubricant to accumulate in the recess 112b, reducing frictional resistance between the surface hardening layer 112a of the shank 12a and the soil, and suppressing the accumulation of soil in the recess 112b. As a result, it is possible to suppress the generation of vibrations due to frictional resistance between the shank 12a and the soil during excavation, while also suppressing the accumulation of soil on the cutter head 1.

[0052] Furthermore, the manufacturing method for the tunnel boring machine 100 of the first embodiment includes, as described above, at least one of the following steps: spraying first fine particles onto the outer surface of the hard tip 11a to form an uneven surface 1111a including a recess 111b and simultaneously forming a surface hardened layer 111a with a modified surface hardness; and spraying second fine particles onto the shank 12a to form an uneven surface 1112a including a recess 112b and simultaneously forming a surface hardened layer 112a with a modified surface hardness. As a result, at least one of the outer surface of the hard tip 11a and the outer surface of the shank 12a can have its outer surface hardness modified to a high hardness by spraying the first or second fine particles, thereby enabling the manufacture of a cutting bit 1a with improved strength. As a result, a tunnel boring machine 100 can be manufactured that can suppress chipping and wear of the cutting bit 1a during excavation. Furthermore, by providing recesses 111b (112b), the contact area with excavated soil is reduced, and the lubricant injected to improve groundwater and excavated soil is held in the recesses 111b (112b), thereby suppressing soil from adhering to the surface of the cutting bit 1a, and enabling the manufacture of a tunnel boring machine 100 that achieves reduced excavation resistance and reduced excavation vibration.

[0053] Furthermore, in the first embodiment, as described above, the step of forming a surface hardened layer 111a on the outer surface of the hard chip 11a includes a step of spraying first fine particles having a diameter of less than 100 μm onto the outer surface of the hard chip 11a to form an uneven surface 1112a including fine recesses 111b having a diameter of less than 100 μm, while simultaneously forming the surface hardened layer 111a. This makes it possible to form a surface hardened layer 111a on the outer surface of the hard chip 11a, thereby enabling the manufacture of a hard chip 11a with improved hardness. In addition, by spraying first fine particles having a diameter of less than 100 μm onto the outer surface of the hard chip 11a to form an uneven surface 1111a including fine recesses 111b having a diameter of less than 100 μm, the hardness of the outer surface of the hard chip 11a can be improved by the impact of the sprayed first fine particles, while the recesses 111b can be easily formed. Furthermore, by providing fine recesses 111b, the contact area of ​​excavated soil is reduced, and the lubricant injected to improve groundwater and excavated soil is held in the recesses 111b, thereby suppressing the adhesion of soil to the hard chips 11a. This makes it possible to manufacture a tunnel boring machine 100.

[0054] Furthermore, in the first embodiment, as described above, the method includes the steps of providing a surface hardening layer 111a on the outer surface of the hard tip 11a and providing a surface hardening layer 112a on the outer surface of the shank 12a. The step of providing a surface hardening layer 112a on the outer surface of the shank 12a includes spraying second fine particles having a diameter at least twice as large as the first fine particles onto the outer surface of the shank 12a to form an uneven surface 1112a including a recess 112b having a diameter at least twice as large as the diameter of the recess 111b provided in the hard tip 11a, and simultaneously forming a surface hardening layer 112a with a modified surface hardness. As a result, by providing a surface hardening layer 111a (112a) on both the outer surface of the hard tip 11a and the outer surface of the shank 12a, the hardness of the hard tip 11a and the shank 12a can be improved, thereby further improving the strength of the cutting bit 1a. As a result, a tunnel boring machine 100 can be manufactured that further suppresses the chipping of the cutting bit 1a during excavation. Furthermore, by providing a recess 112b on the outer surface of the shank 12a, which has a larger diameter than the recess 111b provided on the outer surface of the hard tip 11a, the contact area between the fine soil excavated by the tunnel boring machine 100 and the excavated soil is reduced, and the recess 112b also holds groundwater and lubricant injected to improve the excavated soil. As a result, it is possible to manufacture a tunnel boring machine 100 that can suppress the accumulation of soil on the cutter head 1 during excavation.

[0055] [Second Embodiment] A second embodiment will be described with reference to Figures 1, 6 to 9. In this second embodiment, the shank 12a has a first uneven surface 2112a and a second uneven surface 2112b. In the figures, components similar to those in the first embodiment are denoted by the same reference numerals.

[0056] As shown in Figures 7 and 8, the uneven surface (shank-side uneven surface) of the surface hardened layer 212a provided on the outer surface of the shank 12a in the second embodiment includes a first uneven surface 2112a and a second uneven surface 2112b. The first uneven surface 2112a is formed from a plurality of fine first recesses 212b and a first protrusion 212c. The plurality of fine first recesses 212b have a diameter of less than 100 μm. The second uneven surface 2112b is formed from a second recess 212d and a second protrusion 212e. The second recess 212d has a diameter of five times or more that of the first recess 212b. In the second embodiment, the first uneven surface 2112a is formed on the second uneven surface 2112b. Therefore, the first recess 212b is formed on a part of the bottom surface of the second recess 212d.

[0057] (Manufacturing method for tunnel boring machines) A method for manufacturing the tunnel boring machine 100 will be described based on Figures 6 and 9. The method differs from the first embodiment in that step S2 includes steps S21 and S22. Step S21 is a step of injecting fine particles to form a first uneven surface 2112a including a first recess 212b. Specifically, fine particles of 100 μm or less are injected onto the surface of the shank 12a to form the first recess 212b. In step S22, particles five times larger than the fine particles in step S21 are injected to form a second uneven surface 2112b including a second recess 212d which is five times larger than the first recess 212b. This forms a surface modification structure in which the first recess 212b and the second recess 212d overlap. Note that the order in which steps S21 and S22 are performed is not limited to this order and may be reversed.

[0058] The other configurations of the second embodiment are the same as those of the first embodiment described above.

[0059] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0060] In the second embodiment, as described above, the uneven surface provided on the outer surface of the shank 12a includes a first uneven surface 2112a formed from a plurality of fine first recesses 212b and a second uneven surface 2112b formed from a second recess 212d having a diameter five times or more that of the first recesses 212b, with the first uneven surface 2112a and the second uneven surface 2112b overlapping. As a result, the first uneven surface 2112a formed from a plurality of fine first recesses 212b is formed on the second uneven surface 2112b formed from the second recess 212d having a diameter five times or more that of the first recesses 212b, thereby reducing the contact area between the fine soil particles contained in the first recesses 212b and the larger soil particles, suppressing the adhesion of soil to the surface of the cutting bit 1a, and achieving a reduction in excavation resistance and excavation vibration.

[0061] Furthermore, in the second embodiment, the method includes at least a step of forming a surface hardened layer 212a on the outer surface of the shank 12a, the step of forming a surface hardened layer 212a on the outer surface of the shank 12a includes a step of superimposing the first uneven surface 2112a and the second uneven surface 2112b by spraying fine particles to form a first uneven surface 2112a including a first recess 212b, and spraying particles having a diameter at least five times larger than the fine particles to form a second uneven surface 2112b including a second recess 212d having a diameter at least five times larger than the first recess 212b. This allows for the manufacture of a tunnel boring machine 100 that can effectively reduce the contact area with soil composed of different soil particles, from fine to large, suppressing soil adhesion to the surface of the cutting bit 1a, thereby reducing excavation resistance and excavation vibration. This is achieved by performing both the step of injecting small particles to form the first recess 212b and the step of injecting large particles to form the second recess 212d, in an alternating order, thereby forming a composite structure consisting of a fine first uneven surface 2112a formed from the first recess 212b and a second uneven surface 2112b formed from the second recess 212d.

[0062] Other effects of the second embodiment are the same as those of the first embodiment described above.

[0063] [Differentiation] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than by the description of the embodiments above, and further includes all modifications (exceptions) within the meaning and scope equivalent to the claims.

[0064] For example, the first and second embodiments described above show examples in which the present invention is applied to a mud pressure balance tunnel boring machine, but the present invention is not limited thereto. The present invention may also be applied to a slurry tunnel boring machine.

[0065] Furthermore, while the first and second embodiments described above show examples in which a surface hardening layer is provided on both the hard tip and the shank, the present invention is not limited thereto. In the present invention, a surface hardening layer including an uneven surface formed from fine recesses may be provided on only one of the hard tip or the shank.

[0066] Furthermore, while the first and second embodiments described above show examples where the diameter of the recess provided in the hard tip and the diameter of the recess provided in the shank are different, the present invention is not limited thereto. In the present invention, the diameter of the recess provided in the hard tip and the diameter of the recess provided in the shank may be the same. In this case, the diameter of the first fine particle and the diameter of the second fine particle may be the same.

[0067] Furthermore, while the first and second embodiments described above show examples where the diameter of the recess provided in the shank is larger than the diameter of the recess provided in the hard tip, the present invention is not limited thereto. In the present invention, the diameter of the recess provided in the shank may be smaller than the diameter of the recess provided in the hard tip. In this case, the diameter of the first fine particle may be larger than the diameter of the second fine particle.

[0068] Furthermore, while the first and second embodiments described above show examples in which a surface hardening layer is provided on all surfaces of the hard tip's outer surface other than the surface joined to the shank, the present invention is not limited thereto. In the present invention, a surface hardening layer may be provided on at least one of the surfaces of the hard tip's outer surface other than the surface joined to the shank.

[0069] Furthermore, while the first and second embodiments described above show examples in which a surface hardening layer is provided on all surfaces of the outer surface of the shank other than the surface joined to the hard tip, the present invention is not limited thereto. In the present invention, a surface hardening layer may be provided on at least one of the surfaces of the outer surface of the shank other than the surface joined to the hard tip.

[0070] Furthermore, while the first and second embodiments described above show examples in which no build-up material is formed at the welded portion between the hard tip and the shank, the present invention is not limited thereto. In the present invention, a build-up material may be formed at the welded portion between the hard tip and the shank. In this case, a recess may be provided in the build-up material.

[0071] Furthermore, while the first and second embodiments described above show examples of joining the hard tip and shank by brazing, the present invention is not limited thereto. In the present invention, the hard tip and shank may be joined by methods other than brazing, such as welding.

[0072] Furthermore, while the first and second embodiments described above show examples where a surface hardening layer is provided on the cutting bit provided on the side, the present invention is not limited thereto. In the present invention, a surface hardening layer may also be provided on the cutting bit provided on the front surface.

[0073] Furthermore, in the first and second embodiments described above, an example was shown in which a surface hardening layer is applied to the outer surface of the shank in step S2 after the step of applying a surface hardening layer to the outer surface of the hard tip in step S1, and then the tip and shank are joined (brazed). However, the present invention is not limited to this. In the present invention, steps S1 and S2 do not need to be performed in this order and may be performed simultaneously. Also, a joining step (brazing step) may be included between steps S1 and S2, and steps S1 and S2 may be performed after the joining step. [Explanation of Symbols]

[0074] 1 cutter head 1a Cutting bit 11a Hard Tip 12a Shank 13a Slub material discharge port 111a, 112a Surface hardening layer 111b, 112b recess 100 Tunnel Boring Machines 111a, 112a, 212a Surface hardening layer 111b, 112b recess 212b First recess 212d Second recess 1111a, 1112a Uneven surface 2112a 1st uneven surface 2112b Second uneven surface

Claims

1. A cutting bit comprising a hard tip and a shank to which the hard tip is joined, The cutter head on which the cutting bit is installed comprises A tunnel boring machine, wherein at least one of the outer surface of the hard tip and the outer surface of the shank is provided with a surface hardening layer that includes an uneven surface formed from a plurality of fine recesses, and whose surface has been modified to be highly hard.

2. The tunnel boring machine according to claim 1, wherein the outer surface of the hard chip is provided with the surface hardened layer including the uneven surface formed from the fine recesses having a diameter of less than 100 μm.

3. Both the outer surface of the hard tip and the outer surface of the shank are provided with the surface hardening layer, which includes the uneven surface formed from the recesses. The tunnel boring machine according to claim 2, wherein the diameter of the recess provided on the outer surface of the shank is at least twice as large as the diameter of the recess provided on the outer surface of the hard tip.

4. The tunnel boring machine according to claim 1, wherein the uneven surface provided on the outer surface of the shank includes a first uneven surface formed from a plurality of fine first recesses and a second uneven surface formed from second recesses having a diameter five times or more that of the first recesses, and the first uneven surface and the second uneven surface are provided overlapping.

5. The tunnel boring machine according to claim 1, wherein the outer surface of the shank is provided with the surface hardening layer and a lubricant discharge port arranged in the region where the surface hardening layer is provided for discharging lubricant.

6. A method for manufacturing a tunnel boring machine, comprising a cutting bit including a hard tip and a shank to which the hard tip is joined, and a cutter head on which the cutting bit is installed, A method for manufacturing a tunnel boring machine, comprising at least one of the following steps: spraying first fine particles onto the outer surface of the hard tip to form an uneven surface including recesses and simultaneously form a surface hardened layer that modifies the surface to a high hardness; and spraying second fine particles onto the shank to form an uneven surface including recesses and simultaneously form a surface hardened layer that modifies the surface to a high hardness.

7. The process includes at least the step of forming the surface hardened layer on the outer surface of the hard chip, The method for manufacturing a tunnel boring machine according to claim 6, wherein the step of forming the surface hardened layer on the outer surface of the hard chip includes the step of spraying the first fine particles having a diameter of less than 100 μm onto the outer surface of the hard chip to form the uneven surface including the fine recesses having a diameter of less than 100 μm and simultaneously form the surface hardened layer.

8. The process comprises the steps of forming the surface hardened layer on the outer surface of the hard tip and forming the surface hardened layer on the outer surface of the shank, The method for manufacturing a tunnel boring machine according to claim 7, wherein the step of forming the surface hardened layer on the outer surface of the shank includes spraying the second fine particles having a diameter at least twice that of the first fine particles onto the outer surface of the shank to form the uneven surface including the recess having a diameter at least twice that of the recess provided in the hard tip, and at the same time form the surface hardened layer with a modified surface hardness.

9. The process includes at least the step of forming the surface hardened layer on the outer surface of the shank, The method for manufacturing a tunnel boring machine according to claim 6, wherein the step of forming the surface hardened layer on the outer surface of the shank includes the step of spraying fine particles to form a first uneven surface including a first recess, and spraying particles having a diameter five times or more larger than the fine particles to form a second uneven surface including a second recess having a diameter five times or more larger than the first recess, thereby overlapping the first uneven surface and the second uneven surface.

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