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 enable smooth sliding of the rod within a tube, even when the distance over which the rod slides is large. [Solution] This tunnel boring machine 100 includes a cutter head 1, a body 3 positioned behind the cutter head 1, a tube 4a, and a rod 4b sliding inside the tube 4a, and a hydraulic cylinder, and to cope with lateral loads acting in a direction intersecting the extension and contraction direction, the outer surface 41a of the rod 4b of the hydraulic cylinder is provided with a surface modification layer 40 including fine recesses 40a having a diameter of less than 100 μm.

Description

Technical Field

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

Background Art

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

[0003] Patent Document 1 discloses a tunnel boring machine including a cutter head having cutter bits, a body portion, and a propulsion jack (hydraulic cylinder). In Patent Document 1, the propulsion hydraulic jack is fixed to the body portion and is configured to propel the tunnel boring machine.

[0004] In addition, an example of a hydraulic cylinder is disclosed in Patent Document 2. Patent Document 2 discloses a hydraulic cylinder including a piston and a tube, and a wearing ring as a bearing is attached to the outer peripheral portion of the piston. In Patent Document 2, the wearing ring includes a first wearing ring having a relatively low friction coefficient and a low compressive strength, and a second wearing ring having a high friction coefficient, a high compressive strength, and an outer diameter dimension smaller than that of the first wearing ring. In Patent Document 2, when the lateral load is less than a predetermined value, the second wearing ring does not contact the tube, and the first wearing ring contacts the tube, thereby reducing the frictional resistance between the piston and the tube. When the lateral load becomes greater than or equal to the predetermined value, the first wearing ring contracts, and the second wearing ring contacts the tube, so that the second wearing ring reduces the frictional resistance between the piston and the tube.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, in the case of a double-layered wear ring structure as disclosed in Patent Document 2, the first wear ring does not contract uniformly, causing the piston to tilt significantly. This results in a concentration of lateral loads and relatively high frictional resistance in certain areas, leading to the problem of increased frictional resistance. Therefore, there is a need for a tunnel boring machine equipped with a hydraulic cylinder capable of smoothly sliding the rod inside the tube even under large lateral loads, and a method for manufacturing such a tunnel boring machine.

[0007] 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 smoothly slide a rod inside a tube even when a large lateral load is acting on the rod. [Means for solving the problem]

[0008] To achieve the above objective, the tunnel boring machine of this invention comprises a hydraulic cylinder including a cutter head, a body positioned behind the cutter head, a tube, and a rod sliding inside the tube, and to cope with lateral loads acting in a direction intersecting the extension direction, the outer surface of the rod of the hydraulic cylinder is provided with a surface modified layer having a high hardness, which includes fine recesses having a diameter of less than 100 μm.

[0009] In the tunnel boring machine of this invention, as described above, in order to deal with lateral loads acting in a direction intersecting the expansion and contraction direction, a surface modification layer is provided on the outer surface of the hydraulic cylinder rod, which has been modified to have a high hardness surface and includes fine recesses having a diameter of less than 100 μm. As a result, the fluid (oil) used when sliding the hydraulic cylinder rod can be accumulated in the fine recesses, so that a film is formed by the fluid, reducing the frictional resistance between the inner surface of the tube (or the sliding support portion if one is provided between the inner surface of the tube and the outer surface of the rod) and the outer surface of the rod. As a result, even when the lateral load acting on the rod is large, the frictional resistance between the inner surface of the tube (sliding support portion) and the outer surface of the rod can be reduced, so that the rod can slide smoothly inside the tube even when the lateral load acting on the rod is large. Furthermore, a unique effect of tunnel boring machines is that they can contain foreign matter such as sand that easily enters during tunnel excavation in minute recesses. This suppresses the occurrence of abrasion on the inner surface (sliding support part) of the rod or tube caused by the presence of foreign matter such as sand between the outer surface of the rod and the inner surface (sliding support part) of the tube. In addition, the durability of the rod can be improved by forming a surface modification layer that modifies the hardness of the outer surface of the rod to a high hardness.

[0010] In the tunnel boring machine of this invention, preferably, the hydraulic cylinder includes a propulsion hydraulic jack attached to the body. Here, the propulsion hydraulic jack of the tunnel boring machine is large, the distance (stroke) over which the rod slides inside the tube is relatively long, and relatively large lateral loads are likely to be applied. Therefore, by providing fine recesses on the rod of the propulsion hydraulic jack, the frictional resistance between the inner surface of the tube (sliding support part) and the outer surface of the rod can be effectively reduced even when large lateral loads are applied, thereby enabling the tunnel boring machine to be propelled smoothly.

[0011] In the tunnel boring machine of this invention, preferably, a plating layer is provided on the outer surface of the hydraulic cylinder rod, and a surface modification layer containing fine recesses is formed on the plating layer. With this configuration, by providing a surface modification layer on the plating layer, the rust prevention and scratch resistance of the rod can be improved by the plating layer, while the frictional resistance between the inside of the tube (sliding support part) and the outer surface of the rod can be reduced by the surface modification layer.

[0012] The present invention relates to a method for manufacturing a tunnel boring machine, comprising a tube and a propulsion hydraulic jack including a rod that slides inside the tube, and comprising the step of injecting fine particles onto the rod of the propulsion hydraulic jack to deal with a lateral load acting in a direction intersecting the expansion and contraction direction, thereby forming fine recesses having a diameter of less than 100 μm and simultaneously forming a surface modified layer whose surface has been modified to a high hardness.

[0013] The manufacturing method for the tunnel boring machine of this invention includes a step of injecting fine particles onto the rod of the propulsion hydraulic jack to form fine recesses having a diameter of less than 100 μm and simultaneously form a surface-modified layer with a high hardness, in order to deal with lateral loads acting in a direction intersecting the expansion and contraction direction as described above. As a result, fine recesses can be formed on the rod of the propulsion hydraulic jack, and the fluid (oil) used when sliding the rod of the propulsion hydraulic jack can be accumulated in the formed fine recesses, forming a film that reduces the frictional resistance between the inner surface of the tube (sliding support part) and the outer surface of the rod. As a result, even when the lateral load acting on the rod is large, frictional resistance can be reduced, making it possible to manufacture a tunnel boring machine in which the rod can slide smoothly inside the tube. Furthermore, by injecting fine particles onto the rod of the propulsion hydraulic jack, a surface-modified layer with a high hardness can be formed on the outer surface of the rod, thereby improving the durability of the rod.

[0014] The manufacturing method of the tunnel boring machine of this invention preferably further comprises a step of providing a plating layer on the outer surface of the rod of the propulsion hydraulic jack, and the step of forming a surface modification layer while simultaneously forming fine recesses includes a step of forming a surface modification layer after the step of providing a plating layer on the outer surface of the rod, in order to form fine recesses in the plating layer provided on the rod and to repair cracks formed on the surface of the plating layer during its formation. With this configuration, the rust prevention and scratch resistance of the rod of the propulsion hydraulic jack can be improved by including the step of providing a plating layer on the outer surface of the rod of the propulsion hydraulic jack. Furthermore, since the cracks in the plating layer are repaired by the step of forming a surface modification layer while simultaneously forming fine recesses in the plating layer provided on the outer surface of the rod and to repair cracks formed on the surface of the plating layer during its formation, fluid leakage through the cracks can be suppressed. [Effects of the Invention]

[0015] 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 smoothly slide the rod inside the tube even when a large lateral load is acting on the rod. [Brief explanation of the drawing]

[0016] [Figure 1] This is a cross-sectional view of a tunnel boring machine according to an embodiment, taken from the side. [Figure 2] This is a partial cross-sectional view of a propulsion hydraulic jack according to an embodiment. [Figure 3] This is a cross-sectional view of a rod according to an embodiment. [Figure 4] This is a flowchart of the manufacturing method of a tunnel boring machine according to an embodiment. [Figure 5] This is a partial cross-sectional view of a modified hydraulic jack for propulsion. [Modes for carrying out the invention]

[0017] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0018] (Configuration of Tunnel Boring Machine) Referring to FIGS. 1 to 4, the tunnel boring machine 100 according to the embodiment will be described.

[0019] In each figure, the direction (front - rear direction) parallel to the rotation center axis α of the cutter head 1 extending along the excavation direction (front - rear direction) is indicated by the X - direction. Among the X - direction, the excavation direction (forward) is indicated by the X1 - direction, and the other direction (rearward) is indicated by the X2 - direction. Note that the rotation center axis α is also the center axis of the body 3.

[0020] In each figure, the vertical direction is indicated by the Z - direction. Among the Z - direction, the upward direction is indicated by the Z1 - direction, and the downward direction is indicated by the Z2 - direction.

[0021] As shown in FIG. 1, the tunnel boring machine 100 includes a cutter head 1 and an excavation machine body 2 including a body 3. The tunnel boring machine 100 is, for example, an earth pressure balance type tunnel boring machine.

[0022] (Configuration of Cutter Head) The cutter head 1 has a plurality of cutter bits B on the front surface and is configured to excavate the ground by rotation. The cutter head 1 is supported by a plurality of support legs 1a from the rear. The support legs 1a are fixed to the front surface of an annular support ring 1b.

[0023] (Configuration of Excavation Machine Body) The excavation machine body 2 includes a cylindrical body 3, a plurality of propulsion hydraulic jacks 4, a partition wall 5, a screw conveyor 6, a swivel bearing 7, and a drive source 8. Note that the propulsion hydraulic jack 4 is an example of the "hydraulic cylinder" described in the claims.

[0024] The body section 3 is located behind the cutter head 1. The body section 3 includes a front body section located on the X1 side and a rear body section located on the X2 side. The cutter head 1 is installed at the front end 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 while arranging segments SG on the wall surface by erectors (not shown) to form the perimeter wall of the tunnel as the front body section excavates. 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.

[0025] Multiple propulsion hydraulic jacks 4 are arranged at predetermined angular intervals in the rotational direction (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 driving source for propelling the excavator body 2. The detailed configuration of the propulsion hydraulic jacks 4 will be described later.

[0026] 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.

[0027] 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.

[0028] 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 1b.

[0029] (Detailed configuration of the hydraulic jack for propulsion) As shown in Figure 2, each of the multiple propulsion hydraulic jacks 4 includes a tube 4a and a rod 4b. The propulsion hydraulic jack 4 also includes a piston 4c and a sliding support portion 4d. The propulsion hydraulic jack 4 includes a fluid supply unit (not shown) for supplying fluid (hydraulic oil). The fluid supply unit is configured to supply fluid into the tube 4a from either the X1 side or the X2 side of the tube 4a, and to recover the fluid from the other side.

[0030] In the retracted state, the propulsion hydraulic jack 4 extends as the rod 4b slides in the X2 direction relative to the tube 4a, due to the supply of fluid from the oil tank to the X1 side of the piston 4c by the fluid supply unit. When the propulsion hydraulic jack 4 is retracted, fluid is stored between the tube 4a and the rod 4b, but when it extends, the fluid flows from the X2 side of the tube 4a into the oil tank and is recovered. Similarly, in the extended state, the propulsion hydraulic jack 4 retracts as the rod 4b slides in the X1 direction relative to the tube 4a, due to the supply of fluid from the fluid supply unit to the X2 side of the piston 4c. When the propulsion hydraulic jack 4 is extended, fluid is stored in the tube 4a on the X1 side of the piston 4c, but when it retracts, the fluid flows from the X1 side of the tube 4a into the oil tank and is recovered.

[0031] The tube 4a is cylindrical when viewed from the excavation direction. The tube 4a is provided to extend along the excavation direction. The tube 4a is attached to the body 3. In addition, multiple sliding support parts 4d are attached to the inner surface 43 on the X2 side of the tube 4a and the outer surface of the piston 4c for supporting the load while sliding. The sliding support parts 4d are, for example, wear rings.

[0032] The rod 4b is configured to slide within the tube 4a. The rod 4b is configured to extend and retract along the excavation direction. In the excavation direction, a piston 4c is attached to the end of the rod 4b on the cutter head 1 side. The rod 4b is configured to extend along the excavation direction when the piston 4c is pressed by fluid supplied from the X1 side. As the rod 4b extends, the segment SG is pushed backward, and the reaction force causes the propulsion hydraulic jack 4 to propel the body 3 (tunnel boring machine 100) along the excavation direction.

[0033] As shown in Figure 3, the rod 4b includes a rod body 41 and a plating layer 42. The rod body 41 is a cylindrical member made of carbon steel. The plating layer 42 is provided on the outer surface 41a of the rod body 41. The plating layer 42 is, for example, a hard chromium plating layer. By providing the plating layer 42, the scratch resistance and rust prevention of the rod 4b can be improved. By improving scratch resistance, it is possible to suppress the formation of scratches and the leakage of fluid.

[0034] In this embodiment, a surface modification layer 40 is provided on the outer surface 41a of the rod 4b of the propulsion hydraulic jack 4 to cope with lateral loads acting in a direction intersecting the extension direction. Specifically, the surface modification layer 40 is provided almost entirely on the outer surface 41a of the rod 4b, from one end to the other in the excavation direction. More specifically, a plating layer 42 is provided on the outer surface 41a of the rod 4b, and the surface modification layer 40 is provided on the outer surface of the plating layer 42. Furthermore, the surface modification layer 40 is provided over the entire circumferential surface of the outer surface 41a of the rod 4b. The surface modification layer 40 is configured to increase the hardness of the outer surface 41a of the rod 4b and improve scratch resistance. The surface modification layer 40 is configured to reduce the frictional resistance between the sliding support portion 4d located inside the tube 4a and the outer surface 41a of the rod 4b, thereby facilitating the sliding of the rod 4b inside the tube 4a.

[0035] The surface modification layer 40 includes a plurality of fine recesses 40a. The depth of the fine recesses 40a is less than the thickness of the plating layer 42. The diameter of the fine recesses 40a is less than 100 μm. In the drawing, the diameters of the plurality of fine recesses 40a are shown to be the same size, but the diameters of the plurality of fine recesses 40a may be different from each other. In this case, some of the recesses 40a may be the same size, or they may all be different. In addition to the fine recesses 40a, the surface modification layer 40 may also have depressions with a larger diameter than the fine recesses 40a (diameter of 100 μm or more). The fine recesses 40a are formed, for example, by impacting fine particles by shot peening. The fine particles have a particle size between several tens of μm and several hundred μm (10 μm to 1 mm). The impact of the fine particles increases the hardness of the outer surface 41a of the rod 4b.

[0036] By providing fine recesses 40a on the outer surface 41a of the rod 4b, if foreign matter (for example, soil) enters the tube 4a, the foreign matter will be contained in the recesses 40a, thereby preventing damage to the inner surface 43 of the tube 4a and the outer surface 41a of the rod 4b by the foreign matter. Furthermore, because fine recesses 40a are provided in the plating layer 42, oil reservoirs such as lubricating oil are formed in the recesses 40a, preventing oil depletion. This also enables the rod 4b to slide smoothly.

[0037] As shown in Figure 2, a spherical portion 4e is provided at the X2 end of the rod 4b opposite to the side where the piston 4c is located. Furthermore, a pressing member 4f is provided at the tip of the spherical portion 4e of the rod 4b, which contacts the segment SG. The reaction force generated when the pressing member 4f presses the segment SG propels the tunnel boring machine 100. Lateral loads are generated by the thrust direction of the propulsion hydraulic jack 4 and the inclination of the segment SG. Because the spherical portion 4e is eccentric with respect to the axis of the propulsion hydraulic jack 4, this eccentricity also generates lateral loads on the propulsion hydraulic jack 4. Additionally, when the pressing member 4f and the segment SG are in close contact, a misalignment occurs between the tunnel boring machine 100 and the segment SG, and this misalignment also generates lateral loads on the propulsion hydraulic jack 4 fixed to the body 3 of the tunnel boring machine 100. However, by providing a fine recess 40a, the increase in frictional resistance can be suppressed, thus achieving smooth operation.

[0038] As shown in Figure 2, the piston 4c is provided at the X1-side end of the rod 4b in the excavation direction. The inner surface 43 and sliding support portion 4d of the tube 4a, which is the sliding support for the piston 4c, are not provided with the surface modification layer 40. The sliding support portion 4d is attached to the outer surface of the piston 4c, and the sliding support portion 4d reduces the frictional resistance between the outer surface 41a of the piston 4c and the inner surface 43 and sliding support portion 4d of the tube 4a.

[0039] The sliding support portion 4d is attached to the outer surface of the piston 4c and also to the inner surface 43 of the tube 4a. The sliding support portion 4d attached to the outer surface of the piston 4c moves along the X direction with the piston 4c. The sliding support portion 4d reduces the frictional resistance between the piston 4c and the tube 4a, even without providing a surface modification layer 40 on the inner surface 43 of the tube 4a, which is the sliding support. Furthermore, the sliding support portion 4d attached to the inner surface 43 of the tube 4a is fixed and configured to slidably support the rod 4b. Comparing the support force acting between the piston 4c and the tube 4a with the support force acting between the rod 4b and the tube 4a, the support force acting between the rod 4b and the tube 4a is greater, so the frictional resistance is further reduced by providing a surface modification layer 40 on the outer surface 41a of the rod 4b.

[0040] (Manufacturing method for tunnel boring machines) The manufacturing method for the tunnel boring machine 100 will now be described. First, as step S1, a plating layer 42 is applied to the outer surface 41a of the rod 4b of the propulsion hydraulic jack 4. Specifically, this is a step of forming a hard chromium plating layer on the outer surface 41a of the rod body 41. For example, electroplating is used as a method for applying the plating layer 42. The process of applying the plating layer 42 is to form a thin metal film.

[0041] Step S2 involves forming fine recesses 40a and simultaneously forming a surface modification layer 40. Specifically, in order to cope with lateral loads acting in a direction intersecting the expansion and contraction direction, fine particles are sprayed onto the rod 4b of the propulsion hydraulic jack 4 to form fine recesses 40a with a diameter of less than 100 μm and simultaneously form a surface modification layer 40. The diameter of the formed fine recesses 40a is set randomly, so they may all be the same, all be the same, or some may be the same. For example, shot peening or WPC treatment can be used to form the fine recesses 40a. The diameter of the fine particles is between 10 μm and 1 mm. Step S2 is performed after step S1. Step S2 includes forming fine recesses 40a on the plating layer 42 provided on the rod 4b and simultaneously forming a surface modification layer 40 to repair cracks formed on the surface of the plating layer 42 during its formation. Specifically, the cracks formed in the plating layer 42 are filled and repaired by impacting them with fine particles near the cracks. Furthermore, by spraying fine particles, the surface hardness of the rod 4b is increased, improving its durability. The hydraulic jack 4 for propulsion is then manufactured by combining the tube 4a, the rod 4b, the piston 4c, and the sliding support part 4d. The manufactured hydraulic jack 4 for propulsion is then fixed to the body 3 of the assembled tunnel boring machine 100.

[0042] (Effects of the embodiment) In this embodiment, the following effects can be obtained.

[0043] In this embodiment, as described above, in order to deal with lateral loads acting in a direction intersecting the expansion and contraction direction, a surface modification layer 40 is provided on the outer surface 41a of the rod 4b of the propulsion hydraulic jack 4, which includes fine recesses 40a having a diameter of less than 100 μm, and whose surface has been modified to be highly hard. As a result, the fluid (oil) used when sliding the rod 4b of the propulsion hydraulic jack 4 can be accumulated in the fine recesses 40a, so that a film is formed by the fluid, reducing the frictional resistance between the inner surface 43 of the tube 4a (or the sliding support portion 4d if one is provided between the inner surface 43 of the tube 4a and the outer surface 41a of the rod 4b) and the outer surface 41a of the rod 4b. As a result, even when the lateral load acting on the rod 4b is large, the frictional resistance between the inner surface 43 of the tube 4a (sliding support portion 4d) and the outer surface of the rod 4b can be reduced, so that the rod 4b can slide smoothly inside the tube 4a even when the lateral load acting on the rod 4b is large. Furthermore, a unique effect of the tunnel boring machine 100 is that it can contain foreign matter such as sand that tends to enter during tunnel excavation in the fine recesses 40a, thereby suppressing the occurrence of scratches on the inner surface 43 (sliding support part 4d) of the rod 4b or tube 4a caused by the presence of foreign matter such as sand between the outer surface 41a of the rod 4b and the inner surface 43 (sliding support part 4d) of the tube 4a. In addition, the durability of the rod 4b can be improved by forming a surface modification layer 40 that modifies the hardness of the outer surface 41a of the rod 4b to a high hardness.

[0044] Furthermore, in this embodiment, as described above, the hydraulic cylinder includes a propulsion hydraulic jack 4 attached to the body 3. Here, the propulsion hydraulic jack 4 of the tunnel boring machine 100 is large, and the distance (stroke) over which the rod 4b slides inside the tube 4a is relatively long, making it susceptible to relatively large lateral loads. Therefore, by providing a fine recess 40a on the rod 4b of the propulsion hydraulic jack 4, even when a large lateral load is applied, the frictional resistance between the inner surface 43 (sliding support part 4d) of the tube 4a and the outer surface 41a of the rod 4b can be effectively reduced, thereby enabling the tunnel boring machine 100 to be propelled smoothly.

[0045] Furthermore, in this embodiment, as described above, a plating layer 42 is provided on the outer surface 41a of the rod 4b of the propulsion hydraulic jack 4, and a surface modification layer 40 including fine recesses 40a is formed on the plating layer 42. As a result, by providing the surface modification layer 40 on the plating layer 42, the rust prevention and scratch resistance of the rod 4b can be improved by the plating layer 42, while the frictional resistance between the inner surface 43 (sliding support portion 4d) of the tube 4a and the outer surface 41a of the rod 4b can be reduced by the surface modification layer 40.

[0046] Furthermore, the manufacturing method of the tunnel boring machine 100 of this embodiment includes a step of injecting fine particles onto the rod 4b of the propulsion hydraulic jack 4 in order to deal with lateral loads acting in a direction intersecting the expansion and contraction direction, thereby forming fine recesses 40a having a diameter of less than 100 μm and simultaneously forming a surface modified layer 40 whose surface has been modified to a high hardness. As a result, fine recesses 40a can be formed on the rod 4b of the propulsion hydraulic jack 4, and the fluid (oil) used when sliding the rod 4b of the propulsion hydraulic jack 4 can be accumulated in the formed fine recesses 40a, forming a film that reduces the frictional resistance between the inner surface 43 (sliding support part 4d) of the tube 4a and the outer surface 41a of the rod 4b. As a result, even when the lateral load acting on the rod 4b is large, the frictional resistance can be reduced, and a tunnel boring machine 100 can be manufactured that can smoothly slide the rod 4b inside the tube 4a. Furthermore, by spraying fine particles onto the rod 4b of the propulsion hydraulic jack 4, a surface modification layer 40 can be formed on the outer surface of the rod 4b, thereby improving the durability of the rod 4b.

[0047] Furthermore, in this embodiment, as described above, the step of providing a plating layer 42 on the outer surface 41a of the rod 4b of the propulsion hydraulic jack 4, and the step of forming a surface modification layer 40 at the same time as forming fine recesses 40a, includes a step of forming a surface modification layer 40 immediately after the step of providing a plating layer 42 on the outer surface 41a of the rod 4b, in order to form fine recesses 40a on the plating layer 42 provided on the rod 4b and to repair cracks formed on the surface of the plating layer 42 when the plating layer 42 was formed. As a result, by including the step of providing a plating layer 42 on the outer surface 41a of the rod 4b of the propulsion hydraulic jack 4, the rust prevention and scratch resistance of the rod 4b of the propulsion hydraulic jack 4 can be improved. In addition, by forming a surface modification layer 40 at the same time as forming fine recesses 40a on the plating layer 42 provided on the outer surface 41a of the rod 4b, the cracks in the plating layer 42 are repaired, so it is possible to suppress fluid leakage through the cracks.

[0048] [Differentiation] It should be noted that the embodiments and modifications 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 (modifications) within the meaning and scope equivalent to the claims.

[0049] For example, the above embodiment shows an example of applying the present invention to a mud pressure balance tunnel boring machine, but the present invention is not limited thereto. In this invention, the present invention may also be applied to a slurry tunnel boring machine.

[0050] Furthermore, although the above embodiment shows an example in which the hydraulic cylinder of the present invention is applied to a propulsion hydraulic jack, the present invention is not limited thereto. In the present invention, the hydraulic cylinder may also be applied to a folding jack for correcting or changing the excavation direction of a tunnel boring machine, or to a copy cutter for over-excavation.

[0051] Furthermore, although the above embodiment shows an example in which a plating layer is provided on the outer surface of the hydraulic cylinder rod, the present invention is not limited to this. In the present invention, a plating layer may not be provided on the outer surface of the hydraulic cylinder.

[0052] Furthermore, although the above embodiment shows an example in which the surface modification layer is provided on the outer surface of the rod without providing it on the sliding surface of the piston, the present invention is not limited to this. As shown in Figure 5, in the present invention, in addition to the outer surface of the rod, a surface modification layer 43a including fine recesses 43b may be provided on the inner surface 43 of the tube on which the piston slides. In this case, as shown in Figure 5, sliding support members may or may not be provided on the inner surface of the cylinder and the outer surface of the piston.

[0053] Furthermore, although the above embodiment shows an example in which a surface modification layer is provided on the outer surface of the rod from one end to the other in the drilling direction, the present invention is not limited to this. In the present invention, the surface modification layer may be provided on either one end or the other end of the outer surface of the rod in the drilling direction, or in between. [Explanation of Symbols]

[0054] 1 cutter head 3 Torso 4. Hydraulic jacks for propulsion 4a Tube 4b rod 4c piston 40 Surface Modified Layer 40a recess 41a Outer surface 42 Plating layer 100 Tunnel Boring Machines

Claims

1. cutter head and A body positioned behind the cutter head, A hydraulic cylinder comprising a tube and a rod that slides inside the tube, A tunnel boring machine, wherein the outer surface of the rod of the hydraulic cylinder is provided with a surface modification layer having a high hardness, which includes fine recesses having a diameter of less than 100 μm, in order to cope with lateral loads acting in a direction intersecting the direction of expansion and contraction.

2. The tunnel boring machine according to claim 1, wherein the hydraulic cylinder includes a propulsion hydraulic jack attached to the body.

3. A plating layer is provided on the outer surface of the rod of the hydraulic cylinder. The tunnel boring machine according to claim 1, wherein the surface modification layer including the fine recesses is formed on the plating layer.

4. A method for manufacturing a tunnel boring machine, comprising a hydraulic jack for propulsion including a tube and a rod that slides inside the tube, A method for manufacturing a tunnel boring machine, comprising the step of injecting fine particles onto the rod of the propulsion hydraulic jack in order to deal with a lateral load acting in a direction intersecting the expansion and contraction direction, thereby forming fine recesses having a diameter of less than 100 μm and simultaneously forming a surface modified layer with a highly hardened surface.

5. The process further includes providing a plating layer on the outer surface of the rod of the hydraulic jack used for propulsion, The method for manufacturing a tunnel boring machine according to claim 4, wherein the step of forming the fine recesses and simultaneously forming the surface modification layer includes, after the step of providing the plating layer on the outer surface of the rod, the step of forming the surface modification layer on the plating layer provided on the rod so as to repair cracks formed on the surface of the plating layer during its formation, while simultaneously forming the fine recesses.

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