Center shaft structure in shield tunneling machine

Abstract

This invention provides a center shaft structure that makes it easier to perform maintenance, inspection, repair, and replacement of piping, particularly the connection points, of fluidizing fluids and hydraulic piping installed inside the hollow interior of a rotary cutter. [Solution] In a shield tunneling machine 30, the structure of the center shaft 11 is provided to connect a rotary joint 20 attached to a bulkhead 35 and a rotary cutter 32, and the center shaft 11 is composed of a rotating shaft portion 12 and a sliding sleeve portion 13. The sliding sleeve portion 13 has a portion that can slide back and forth in the axial direction X' of the rotating shaft portion 12 along the outer circumferential surface of the other end portion 12b of the rotating shaft portion 12, with at least the rear end portion 13a being released from being fixed to the other end portion 12b of the rotating shaft portion 12.

Description

Technical Field

[0001] The present invention relates to a center shaft structure for a shield excavator, and particularly to a center shaft structure for a shield excavator provided to connect a rotary joint attached to a partition wall that partitions a cutter chamber and a rotary cutter.

Background Art

[0002] As a shield excavator having a rotary cutter at the front, for example, a mud pressure-type shield excavator cuts the ground at the face with the rotary cutter, takes the generated sediment into the cutter chamber, and supplies a liquid material containing a plastic fluidizing agent, preferably a mud-making agent or the like, as a chemical liquid to the generated sediment into the cutter chamber via the rotary cutter for mixing, thereby generating plastic-fluidized mud. The mud pressure generated by the cutter chamber being filled with the generated mud stabilizes the face while excavating the ground of the face. Also, in other shield excavators such as a slurry-type shield excavator, various chemical liquids are fed as needed from the rear of the partition wall partitioning the cutter chamber through respective pipelines, and supplied to the rotary cutter and the cutter chamber.

[0003] In these shield tunneling machines, the chemical fluid fed from behind the bulkhead and supplied to the rotary cutter and cutter chamber is supplied to the rotary cutter at the front, which is driven by rotation, from a rear piping system that does not have a rotating mechanism, along with the hydraulic pressure that drives the copy cutter, for example. Therefore, a known rotary joint is attached to the bulkhead to connect the flow paths of the chemical fluid and hydraulic pressure between them (see, for example, Patent Document 1). In the shield tunneling machine described in Patent Document 1, the rotary joint is configured to include a fixed housing portion, which is the main body portion, fixed to the central part of the rear side of the bulkhead in the direction of excavation, and a rotating shaft portion, which functions as a center shaft, and is rotatably and liquid-tightly supported via a rotating support portion provided in an insertion hole formed in the bulkhead, and extends into the interior of the cutter chamber at the front. The fixed housing portion, which is the main body of the rotary joint, is equipped with one or more known rotating inner grooves extending in the circumferential direction inside it. Chemicals and hydraulic fluids sent from piping passages connected to these rotating inner grooves can pass through these grooves and then be sent to piping passages on the cutter side, which are formed inside the rotating shaft portion that rotates together with the rotary cutter and communicate with these rotating inner grooves.

[0004] Furthermore, the piping on the cutter side, formed inside the rotating shaft that functions as the center shaft, is joined to the rotary cutter with the tip of the rotating shaft protruding into the hollow interior by penetrating the back plate of the circular base in the central part of the rotary cutter. This connects the piping formed inside the rotating shaft to the piping arranged on the cutter spokes that extend radially from the circular base within the hollow interior of the circular base of the rotary cutter. By connecting the piping formed inside the rotating shaft to these piping arranged on the cutter spokes, the fluidizing liquid and hydraulic pressure supplied from the rotary joint through the piping can be sent to discharge ports located at predetermined positions on the front of the circular base of the rotary cutter or on the front of the cutter spokes, for example, and discharged from these discharge ports toward the cutting face. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2024-62854 [Overview of the project] [Problems that the invention aims to solve]

[0006] On the other hand, in the shield tunneling machine described in Patent Document 1, the rotating shaft, which functions as the center shaft, has a tip portion on its outer circumference that has a connection port to the internal piping system, which protrudes into the hollow interior of the circular base portion of the rotary cutter. This structure makes it impossible to perform maintenance, inspection, repair, or replacement as needed on the connection status of the piping for supplying fluidizing liquid and hydraulic fluid, which is routed inside the hollow interior of the circular base portion of the rotary cutter and the cutter spokes, particularly the connection port on the outer circumference of the tip portion of the rotating shaft. For this reason, in tunneling work involving long-distance tunneling using a shield tunneling machine, if a malfunction occurs at the connection point of these piping systems due to some factor, making it difficult to supply fluidizing liquid and hydraulic fluid to the rotary cutter, it may be necessary to interrupt the tunneling by the shield tunneling machine and perform extensive work to resolve the problem, such as dismantling and restoring the circular base portion of the rotary cutter to which the tip portion of the rotating shaft is fixed, which could lead to a significant extension of the construction period.

[0007] For these reasons, there is a need to develop technology that allows for easier maintenance, inspection, repair, and replacement of pipes, particularly connection points, for fluidizing fluids and hydraulics, which are preferably routed inside the hollow interior of a rotary cutter, as needed. This would enable efficient tunneling work using a shield tunneling machine, even when the construction distance is long, without interrupting the excavation process for extended periods.

[0008] Furthermore, when the length of tunneling work using a shield tunneling machine becomes long, and the geological composition of the ground being tunneled changes significantly along the way, for example from a hard clay layer to a gravelly sandy soil layer, it may become necessary to replace the rotary cutter, preferably at an intermediate shaft. With conventional shield tunneling machines, replacing the rotary cutter involves splitting the center shaft and removing the rotary cutter from the bulkhead, which results in the severing of piping inside the center shaft. Consequently, restoring the piping after replacing the rotary cutter is extremely time-consuming. For these reasons, there is a need for the development of technology that allows for easier replacement of the rotary cutter.

[0009] The present invention aims to provide a center shaft structure for a shield tunneling machine that makes it easier to perform maintenance, inspection, repair, and replacement of piping for fluidizing liquids and hydraulics, particularly the connection parts, which are routed inside the hollow interior of the rotary cutter, and preferably makes it easier to replace the rotary cutter. [Means for solving the problem]

[0010] The present invention relates to a shield tunneling machine having a rotary cutter at the front, and a rotary joint attached to the central part of a partition wall that divides the cutter chamber behind the rotary cutter, enabling the delivery of chemicals and the like from the rear to the rotary cutter, and a center shaft structure provided to connect the rotary cutter, wherein one end of the center shaft is connected to the rotary joint located at the rear of the cutter chamber, and the other end is rotatably inserted and supported by a rotating support provided in the partition wall, and the other end protrudes into the interior of the cutter chamber. The above objective is achieved by providing a center shaft structure for a shield tunneling machine that includes a rotating shaft portion and a cylindrical slide sleeve portion having an inner cross-sectional shape similar to the outer cross-sectional shape of the other end portion of the rotating shaft portion, the rear end portion being detachably fixed to the other end portion of the rotating shaft portion, and the front end portion being detachably fixed to the back surface of the rotating cutter, and the slide sleeve portion having a portion that can slide back and forth in the axial direction of the rotating shaft portion along the outer circumferential surface of the other end portion of the rotating shaft portion, at least when the rear end portion is released from being fixed to the other end portion of the rotating shaft portion.

[0011] Furthermore, in the shield tunneling machine of the present invention, it is preferable that the center shaft structure is such that the slide sleeve portion is fixed to the other end of the rotating shaft portion by fastening a fixing bolt to a fastening hole formed on the outer circumferential surface of the rear end portion, and is also fixed to the rear of the rotating cutter portion by fastening a fixing bolt to a fastening hole formed in a joining flange that extends outward from the front end portion.

[0012] Furthermore, in the center shaft structure of the shield tunneling machine of the present invention, it is preferable that the other end portion of the rotating shaft portion to which the rear end portion of the slide sleeve portion is fixed has a larger diameter than the portion that is inserted and supported by the rotating support portion.

[0013] Furthermore, it is preferable that the center shaft structure in the shield tunneling machine of the present invention comprises a front sleeve portion on the rotary cutter side and a rear sleeve portion on the rotary joint side, which are divisibly connected as a single unit, and that the rear sleeve portion can be separated from the front sleeve portion, allowing only the rear sleeve portion to slide back and forth along the outer circumferential surface of the other end of the rotating shaft portion.

[0014] Furthermore, in the center shaft structure of the shield tunneling machine of the present invention, it is preferable that the front sleeve portion and the rear sleeve portion are connected as a single unit in a separable manner by fastening fixing bolts to fastening holes formed in a connecting flange that extends outward from the rear end of the front sleeve portion and to fastening holes formed in a connecting flange that extends outward from the front end of the rear sleeve portion.

[0015] Furthermore, in the center shaft structure of the shield tunneling machine of the present invention, it is preferable that piping for chemicals and the like, extending from the rotating shaft towards the rotating cutter, is detachably arranged in the slide sleeve portion via a connector member. [Effects of the Invention]

[0016] According to the center shaft structure of the shield tunneling machine of the present invention, maintenance, inspection, repair, and replacement of pipes for fluidizing liquids and hydraulics, particularly the connection parts, which are routed inside the hollow interior of the rotary cutter can be performed more easily, and preferably, the operation of replacing the rotary cutter can be performed more easily. [Brief explanation of the drawing]

[0017] [Figure 1] This is a longitudinal cross-sectional view of a mud pressure balance type shield tunneling machine employing a center shaft structure in a shield tunneling machine according to a preferred embodiment of the present invention. [Figure 2]This is an enlarged cross-sectional view of part A in Figure 1, illustrating the center shaft structure in a shield tunneling machine according to a preferred embodiment of the present invention. [Figure 3] This is an enlarged cross-sectional view of part A in Figure 1, showing the center shaft in cross-section, illustrating the state when the slide sleeve is slid. [Figure 4] This is an enlarged cross-sectional view of part A in Figure 1, showing a cross-section of the center shaft, illustrating another state where the slide sleeve has been slid into place. [Figure 5] This is a longitudinal cross-sectional view of a mud pressure balance type shield tunneling machine, illustrating the state after removing the rotary cutter while leaving the rotary joint in place when replacing the rotary cutter. [Modes for carrying out the invention]

[0018] A preferred embodiment of the present invention provides a center shaft structure 10 in a shield tunneling machine (see Figures 2 and 3), which is a mud pressure type shield tunneling machine 30, preferably as shown in Figure 1, having a rotary cutter 32 at the front. The center shaft structure 10 is attached to the central part of a partition wall 35 that divides the cutter chamber 31 behind the rotary cutter 32, and is provided to connect the rotary joint 20, which enables the chemical solution sent from the rear to be fed to the rotary cutter 32, to the rotary cutter 32. As shown in Figures 2 and 3, the center shaft structure 10 of this embodiment makes it easier to perform maintenance, inspection, repair, and replacement of the piping 18 for supplying fluidizing liquid and hydraulic pressure, which is routed inside the hollow interior of the center shaft 11 and the rotary cutter 32, as needed.

[0019] Further, in the center shaft structure 10 of the present embodiment, when the construction extension of the excavation work by the shield machine 30 becomes a long distance, and the geology of the ground to be excavated greatly changes in the middle, for example, from a hard clay layer to a gravel-mixed sandy soil layer, the work of replacing the rotary cutter 32, preferably in an intermediate shaft, can be performed more easily (see FIG. 5).

[0020] Here, as shown in FIG. 1, the preferably mud pressure type shield machine 30 used in the present embodiment cuts the ground at the face 33 with a rotary cutter 32, mixes a liquid material preferably containing a plastic fluidizing agent such as a mud-making agent as a chemical liquid into the earth and sand taken into the cutter chamber 31, and stirs the mixture to generate plastic-fluidized mud. The shield machine excavates the ground of the face 33 while stabilizing the face 33 by the mud pressure generated by filling the generated mud into the cutter chamber 31. As the shield machine 30 excavates the ground of the face 33 and moves forward, the plastic-fluidized mud is discharged to the rear of the shield machine 30 through a screw conveyor 36 having one end opened at the partition wall 35.

[0021] Further, in such a mud pressure type shield machine 30, the chemical liquid and hydraulic pressure fed from the rear of the partition wall 35 and supplied to the rotary cutter 32 and the cutter chamber 31 are supplied from a rear pipe line (not shown) that does not include a rotation mechanism to the rotationally driven front rotary cutter 32. Therefore, a known rotary joint 20 for communicating the flow paths of the chemical liquid and hydraulic pressure between these parts is attached to the partition wall 35. The rotary joint 20 includes a fixed housing portion 20a, which is a main body portion of the rotary joint 20 attached to the rear side of the partition wall 35 in the excavation direction X, and a rotary shaft portion 12 which is rotatably and liquid-tightly supported via a known rotary support portion 40 (see FIG. 2) including a dust wiper and a bearing mechanism and provided in an insertion hole 35a formed in the partition wall 35, with a distal end side portion extending into the cutter chamber 31. The rotary shaft portion 12 of the rotary joint 20 constitutes a rear end side portion of the center shaft 11.

[0022] As described above, the center shaft structure 10 in the shield tunneling machine of the present embodiment is applied to a shield tunneling machine 30 (see FIG. 1) having a rotary cutter 32 at the front end, wherein the center shaft structure 10 is a structure of a center shaft 11 (see FIG. 1) provided to connect a rotary joint 20 attached to a central portion of a partition wall 35 defining a cutter chamber 31 behind the rotary cutter 32, to the rotary cutter 32. As shown in FIG. 2 and FIG. 3, in the center shaft 11, one end 12a is connected to a fixed housing portion 20a that is a main body portion of the rotary joint 20 disposed behind the cutter chamber 31, and is rotatably inserted and supported by a rotation support portion 40 provided on the partition wall 35; the center shaft 11 includes: a rotating shaft portion 12, which is also the rotating shaft portion of the rotary joint 20, with the other end portion 12b protruding into the cutter chamber 31; and a cylindrical slide sleeve portion 13, which has an inner peripheral cross-sectional shape identical to the outer peripheral cross-sectional shape of the other end portion 12b of the rotating shaft portion 12, a rear end portion 13a is detachably fixed to the other end portion 12b of the rotating shaft portion 12, and a front end portion 13b is detachably fixed to the back face of the rotary cutter 32. Furthermore, the slide sleeve portion 13 includes a portion that can slide forward and backward in the axial direction X' of the rotating shaft portion 12 along the outer peripheral surface of the other end portion 12b of the rotating shaft portion 12 in a state where at least the fixation of the rear end portion 13a to the other end portion 12b of the rotating shaft portion 12 is released (see FIG. 3 and FIG. 4). The portion that can slide forward and backward in the axial direction X' of the rotating shaft portion 12 can be, for example, the entire slide sleeve portion 13 (see FIG. 3), or can be a part of the slide sleeve portion 13 (see FIG. 4).

[0023] Furthermore, in the present embodiment, the slide sleeve portion 13 is fixed to the other end portion 12b of the rotating shaft portion 12 by fastening a fixing bolt 14a into a fastening hole 13c formed on the outer peripheral surface of the rear end portion 13a, and is fixed to the back face of the rotary cutter 32 by fastening a fixing bolt 14b into a fastening hole 13e formed in a joint flange 13d provided to project outward from the front end portion 13b.

[0024] Furthermore, in this embodiment, the slide sleeve portion 13 consists of a front sleeve portion 15 on the rotary cutter 32 side and a rear sleeve portion 16 on the rotary joint 20 side, which are connected as a single unit in a separable manner. The rear sleeve portion 16 can be separated from the front sleeve portion 15, and only the rear sleeve portion 16 can be slid forward and backward along the outer circumferential surface of the other end 12b of the rotating shaft portion 12 (see Figure 4). The front sleeve portion 15 and the rear sleeve portion 16 are connected as a single unit in a separable manner by fastening a fixing bolt 14c to a fastening hole 15b formed in a connecting flange 15a that extends outward from the rear end of the front sleeve portion 15, and to a fastening hole 16b formed in a connecting flange 16a that extends outward from the front end of the rear sleeve portion 16.

[0025] In this embodiment, the earth pressure balance type shield tunneling machine 30 is preferably a folding type, as shown in Figure 1, and has the same structure as a known earth pressure balance type shield tunneling machine, as described above. The shield tunneling machine 30 is equipped with a rotary cutter 32, a bulkhead 35, a cutter chamber 31, a cutter drive device 34, as well as a front body outer casing 37a, a rear body outer casing 37b, a shield jack 38, a folding jack 39, an erector device 41, etc. Inside the rear body outer casing 37b, the erector device 41 assembles the segments 42 into a ring shape to sequentially form the primary lining 43, and by extending the shield jack 38 while obtaining a reaction force from the primary lining 43 formed by the segments 42, the machine can advance in the tunneling direction X while cutting the ground at the face 33 with the rotary cutter 32.

[0026] Furthermore, in this embodiment, the rotary cutter 32 has a center shaft 11 which is an integrated rotating shaft portion 12 and a sliding sleeve portion 13. The center shaft 11 extends from the fixed housing portion 20a, which is the main body portion of the rotary joint 20 fixed to the central part of the rear side surface of the partition wall 35 in the excavation direction X, through the partition wall 35 into the inside of the cutter chamber 31. The front end portion 13b of the sliding sleeve portion 13 of the center shaft 11 is firmly joined and fixed to the rear surface of the circular base portion 32a of the rotary cutter 32. This allows the rotating shaft portion 12, which is also part of the rotary joint 20, to rotate simultaneously with the rotation of the rotary cutter 32.

[0027] Furthermore, in this embodiment, multiple cutting spokes 32b, to which cutting bits 32c are fixed, are integrally attached, extending in all directions from the circular base portion 32a of the rotary cutter 32. Also, a center bit 32d is integrally attached, protruding forward in the drilling direction X from the central portion where the circular base portion 32a of the rotary cutter 32 is provided. In this embodiment, a supply port 32e for the fluidizing liquid, which is the chemical solution, is provided in a total of two locations: one location in the central portion of the circular base portion 32a of the rotary cutter 32, where it partially overlaps with the center bit 32d when viewed from the front, and one location on the tip portion of a selected cutting spoke 32b.

[0028] Furthermore, in this embodiment, each of the cutting spokes 32b has a rotating rod portion 32f attached to it, extending to the rear in the excavation direction X, with its rear end joined to the annular rotating rail member 46 of the rotary drive mechanism 45. The annular rotating rail member 46 is engaged with the cutter drive device 34, preferably a hydraulic motor, which is fixed to the partition wall 35 inside the connection box 47, for example, by a gear mechanism. This makes it possible to transmit the rotational driving force from the cutter drive device 34 to the cutting spokes 32b via the annular rotating rail member 46 and the rotating rod portion 32f. This also allows the rotary cutter 32 to rotate stably with a predetermined rotational torque, enabling efficient cutting of the ground at the face 33 by the cutting bit 32c and the center bit 32d.

[0029] In this embodiment, the center shaft structure 10 in the shield tunneling machine is a center shaft 11 structure provided to connect the rotary joint 20 attached to the partition wall 35 that partitions the cutter chamber 31 and the rotary cutter 32, as described above. As shown in Figures 2 and 3, one end 12a of the center shaft 11 is connected to the fixed housing portion 20a, which is the main body portion of the rotary joint 20 located behind the cutter chamber 31, and is rotatably inserted and supported by a known rotating support portion 40 provided on the partition wall 35, with the other end portion 12b connected to the cutter The cutter 31 includes a rotating shaft portion 12 that protrudes forward, and a cylindrical slide sleeve portion 13 that has an inner cross-sectional shape similar to the outer cross-sectional shape of the other end portion 12b of the rotating shaft portion 12, with its rear end portion 13a detachably fixed to the other end portion 12b of the rotating shaft portion 12 and its front end portion 13b detachably fixed to the back surface of the rotating cutter 32. The slide sleeve portion 13 has a portion that can slide back and forth along the outer circumferential surface of the other end portion 12b of the rotating shaft portion 12 in the axial direction X' of the rotating shaft portion 12, at least when the rear end portion 13a is released from the other end portion 12b of the rotating shaft portion 12 (see Figures 3 and 4).

[0030] In this embodiment, the center shaft 11 is composed of a rotating shaft portion 12 and a slide sleeve portion 13. The rotating shaft portion 12 uses a rotating shaft portion that constitutes a known rotary joint 20, and is rotatably joined to the fixed housing portion 20a, which is the main body portion of the rotary joint 20, by a known method. Inside the rotating shaft portion 12, there are multiple piping passages 12c that communicate with multiple rotating inner circumferential grooves that extend circumferentially inside the fixed housing portion 20a. These multiple piping passages 12c serve as passages that send chemical liquids and hydraulic pressures that are sent through the rotating inner circumferential grooves of the fixed housing portion 20a toward the rotary cutter 32, and are formed to extend through the rotating shaft portion 12 in the axial direction X' of the rotating shaft portion 12 from the rear end face of one end to the front end face of the other end. These multiple piping lines 12c preferably have their ends protruding from the other end surface of the rotating shaft portion 12, so that they are connected via various known connector members 17a to piping 18 arranged inside the hollow interior of the rotary cutter 32, preferably inside the hollow interior of the slide sleeve portion 13.

[0031] Furthermore, in this embodiment, the rotating shaft portion 12 of the center shaft 11 is preferably such that the other end portion 12b of the rotating shaft portion 12 to which the rear end portion 13a of the slide sleeve portion 13 is fixed is wider in diameter than the portion that is inserted and supported by the rotating support portion 40. Along this wider other end portion 12b, the entire or a part of the center shaft 11, which has an inner cross-sectional shape similar to the outer cross-sectional shape of the other end portion 12b, is able to slide back and forth in the axial direction X' of the rotating shaft portion 12.

[0032] The slide sleeve portion 13 of the center shaft 11 is made of a cylindrical member, preferably made of steel, having an inner diameter of, for example, about 240 mm. In this embodiment, the slide sleeve portion 13 preferably consists of a front sleeve portion 15 on the rotary cutter 32 side and a rear sleeve portion 16 on the rotary joint 20 side, which are connected as a single unit in a separable manner, as described above, and has a total length of, for example, about 560 mm. As described above, the front sleeve portion 15 and the rear sleeve portion 16 are connected as a single unit in a separable manner by fastening the joining flange 15a at the rear end of the front sleeve portion 15 and the joining flange 16a at the front end of the rear sleeve portion 16 using fixing bolts 14c.

[0033] Furthermore, as described above, the slide sleeve portion 13 is fixed to the other end portion 12b of the rotating shaft portion 12 by fastening a fixing bolt 14a to a fastening hole 13c formed on the outer circumferential surface of the rear end portion 13a by the rear sleeve portion 16, for example, and is fixed to the back surface of the circular base portion 32a of the rotary cutter 32 by fastening a fixing bolt 14b to a fastening hole 13e formed in the joining flange 13d which extends outward from the front end portion 13b by the front sleeve portion 15.

[0034] As a result, in the center shaft structure 10 of this embodiment, when the fixing bolt 14a of the rear end portion 13a of the slide sleeve portion 13 to the other end portion 12b of the rotating shaft portion 12 is released, and the fixing bolt 14b of the front end portion 13b to the back surface of the circular base portion 32a of the rotary cutter 32 is released, the entire slide sleeve portion 13 becomes capable of sliding back and forth along the outer circumferential surface of the other end portion 12b of the rotating shaft portion 12 in the axial direction X' of the rotating shaft portion 12, and by retracting the slide sleeve portion 13, a gap can preferably be created between the back surface of the circular base portion 32a of the rotary cutter 32 and the front end portion 13b (see Figure 3). Through the created gap, maintenance, inspection, repair, and replacement of the piping 18 for fluidizing liquids and hydraulics, especially the connection portions, can be performed.

[0035] Furthermore, for example, when the fixing bolt 14a at the rear end 13a of the slide sleeve portion 13 to the other end portion 12b of the rotating shaft portion 12 is released, and the fixing bolt 14c at the joint flange 16a of the rear sleeve portion 16 and the joint flange 15a of the front sleeve portion 15 is released, the rear sleeve portion 16 of the slide sleeve portion 13 becomes able to slide back and forth along the outer circumferential surface of the other end portion 12b of the rotating shaft portion 12 in the axial direction X' of the rotating shaft portion 12. By retracting only the rear sleeve portion 16, a gap can preferably be created between the joint flange 15a at the rear end of the front sleeve portion 15 and the joint flange 16a at the tip of the rear sleeve portion 16 (see Figure 4). Through the created gap, maintenance, inspection, repair, and replacement of the piping 18 for fluidizing liquids and hydraulics, especially the connection parts, can be performed.

[0036] In the center shaft structure 10 of this embodiment, preferably, within the hollow interior of the slide sleeve portion 13 of the center shaft 11, the piping 18 disposed within the hollow interior of the rotary cutter 32 is detachably connected to a plurality of piping passages 12c that deliver fluidizing liquid or hydraulic pressure from the rotary joint 20 formed on the rotating shaft portion 12. That is, the ends of the plurality of piping passages 12c each protrude from the tip surface on the other end of the rotating shaft portion 12, and the piping 18 for chemicals, etc., disposed in the rotary cutter 32, which extends to the slide sleeve portion 13, is detachably connected to these ends via a connector member 17a. As a result, the piping 18 extending from the rotating shaft portion 12 toward the rotary cutter 32 is detachably disposed within the slide sleeve portion 13 via the connector member 17a. Furthermore, in this embodiment, other piping 18 arranged inside the hollow interior of the rotary cutter 32 can be extended from the hollow interior of the rotary cutter 32 to the hollow interior of the slide sleeve portion 13 via a cutter-side connector member 17b attached to the rear side of the circular base portion 32a of the rotary cutter 32.

[0037] Furthermore, with the center shaft structure 10 of this embodiment having the above configuration, maintenance, inspection, repair, and replacement of the connections made by connector members 17a and 17b of the piping for fluidizing liquids and hydraulics, which is routed inside the hollow interior of the rotary cutter 32, can be performed more easily.

[0038] In other words, according to this embodiment, the center shaft 11 is composed of a rotating shaft portion 12 and a cylindrical sliding sleeve portion 13, and the sliding sleeve portion 13 has a portion that can slide back and forth in the axial direction X' of the rotating shaft portion 12 along the outer circumferential surface of the other end portion 12b of the rotating shaft portion 12, at least when the rear end portion 13a is released from being fixed to the other end portion 12b of the rotating shaft portion 12.

[0039] This allows for easier maintenance, inspection, repair, and replacement of the connection points of the fluidizing liquid and hydraulic piping 18 through the created gap, without requiring extensive work such as dismantling or restoring the circular base 32a of the rotary cutter 32. For example, in an intermediate shaft, or after ground improvement by chemical grouting in the surrounding ground, the work in the cutter chamber 31 after removing the mud can be released, and the entire slide sleeve 13 or the rear sleeve 16 can be slid along the outer surface of the rotating shaft 12 to create an inspection gap.

[0040] Furthermore, according to this embodiment, the center shaft 11 can be separated by releasing the fastening by fixing bolts 14a, 14b, and 14c at the joint between the front end 13b of the slide sleeve portion 13 and the back of the circular base portion 32a of the rotary cutter 32, the joint between the front sleeve portion 15 and the rear sleeve portion 16, and the joint between the rear end 13a of the slide sleeve portion 13 and the other end portion 12b of the rotating shaft portion 12. In addition, the piping 18 can be separated at the connector members 17a and 17b within the hollow interior of the slide sleeve portion 13 of the center shaft 11.

[0041] This makes it possible to perform the work of replacing the rotary cutter 32 more easily, for example, when the construction distance of the tunneling work by the shield tunneling machine 30 becomes long and the geological composition of the ground being tunneled changes significantly along the way, for example from a hard clay layer to a gravelly sandy soil layer. Preferably, when replacing the rotary cutter 32 in an intermediate shaft, the entire rotary joint 20 does not need to be replaced together with the rotary cutter 32. Instead, the piping 18 can be separated at the connector members 17a and 17b, and only the rotary cutter 32 can be replaced while leaving the fixed housing portion 20a and the rotating shaft portion 12 of the rotary joint 20 in place.

[0042] It should be noted that the present invention is not limited to the embodiments described above and can be modified in various ways. For example, the other end of the rotating shaft to which the rear end of the slide sleeve portion is fixed does not necessarily have to be a larger diameter portion than the portion inserted and supported by the rotating support portion, and the slide sleeve portion does not necessarily have to consist of a front sleeve portion and a rear sleeve portion that are connected as a single unit in a separable manner. The present invention can also be applied to shield tunneling machines other than earth pressure balance type shield tunneling machines, such as slurry type shield tunneling machines equipped with a center shaft. [Explanation of symbols]

[0043] 10 Center shaft structure 11 Center shaft 12 Rotating shaft section 12a One end 12b Other end portion 12c pipe line 13 Slide sleeve section 13a Rear end 13b Front end 13c, 13e fastening holes 13d Joint flange 14a, 14b, 14c Fixing bolts 15 Front sleeve section 15a Joining flange 15b Fastening hole 16 Rear sleeve section 16a Joining flange 16b Fastening hole 17a, 17b Connector components 18 Piping 20 Rotary Joint 20a Fixed housing section 30 Shield tunneling machine 31 Cutter Chambers 32 RPM cutter 32a Circular base section 32b Machined spokes 33. The face of the tunnel 35 Bulkhead 40 Rotating support section X Excavation direction X' Axial axis of the rotational shaft

Claims

1. In a shield tunneling machine having a rotary cutter at the front, a rotary joint is attached to the central part of the partition wall that divides the cutter chamber behind the rotary cutter, enabling the delivery of chemicals and the like from the rear to the rotary cutter. The structure of the center shaft is provided to connect the rotary cutter to the rotary joint, The center shaft has one end connected to the rotary joint located at the rear of the cutter chamber, and is rotatably inserted and supported by a rotating support portion provided in the partition wall, with the other end protruding into the interior of the cutter chamber. It comprises a cylindrical slide sleeve portion having an inner circumferential cross-sectional shape similar to the outer circumferential cross-sectional shape of the other end of the rotating shaft portion, the rear end of which is detachably fixed to the other end of the rotating shaft portion, and the front end of which is detachably fixed to the back of the rotary cutter. Furthermore, the center shaft structure in a shield tunneling machine is provided with a portion of the slide sleeve that is capable of sliding back and forth in the axial direction of the rotating shaft along the outer circumferential surface of the other end of the rotating shaft, at least when the rear end of the slide sleeve is released from being fixed to the other end of the rotating shaft.

2. The center shaft structure in a shield tunneling machine according to claim 1, wherein the slide sleeve portion is fixed to the other end of the rotating shaft portion by fastening a fixing bolt to a fastening hole formed on the outer circumferential surface of the rear end portion, and is fixed to the rear of the rotating cutter by fastening a fixing bolt to a fastening hole formed in a joining flange that extends outward from the front end portion.

3. The center shaft structure in a shield tunneling machine according to claim 1 or 2, wherein the other end of the rotating shaft to which the rear end of the slide sleeve is fixed is a portion with a larger diameter than the portion that is inserted and supported by the rotating support.

4. The slide sleeve portion comprises a front sleeve portion on the rotary cutter side and a rear sleeve portion on the rotary joint side, which are divisibly connected as a single unit, and the rear sleeve portion can be separated from the front sleeve portion and only the rear sleeve portion can be slid forward and backward along the outer circumferential surface of the other end of the rotating shaft portion, as described in claim 1 or 2 of the center shaft structure for a shield tunneling machine.

5. The center shaft structure in a shield tunneling machine according to claim 4, wherein the front sleeve portion and the rear sleeve portion are connected as a single unit in a separable manner by fastening fixing bolts to fastening holes formed in a joining flange extending outward from the rear end of the front sleeve portion and to fastening holes formed in a joining flange extending outward from the front end of the rear sleeve portion.

6. The center shaft structure in a shield tunneling machine according to claim 1 or 2, wherein piping for chemicals and the like, extending from the rotating shaft portion toward the rotating cutter, is detachably arranged in the slide sleeve portion via a connector member.

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