Bit switching device

Abstract

To provide a compact bit replacing device capable of easily and safely replacing a bit.SOLUTION: This shield machine is provided with a rotary base 3 1 rotatably provided on a rotary head 2 of the shield machine 1 and having a plurality of bits 30 capable of projecting and retracting from the rotary head 2, and a vertical jack 3 2 fixedly provided on the rotary head 2 and pushing and pulling the bits 30 arranged at a prescribed position by the rotation of the rotary base 3 1 to project and retract them from the rotary head 2. The bit 30 has a first engaging part 303, the projecting / retracting means 32 has a second engaging part 322, the first engaging part 303 and the second engaging part 322 are engaged with each other to push / pull the bit 30, and the first engaging part 303 and the second engaging part 322 are engaged / disengaged by the rotation of the rotary base 31.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a bit changing device provided on a tunnel boring machine having a rotating head. [Background technology]

[0002] In recent years, tunnel construction using tunnel boring machines such as shield machines has become noticeably larger in diameter, longer in distance, and deeper. When excavating long-distance tunnels, there is a concern that the bit attached to the rotary head will wear out during the excavation.

[0003] In particular, when drilling long distances through sand or gravel layers, the carbide tip at the tip of the bit will wear down or chip, making it necessary to replace the bit.

[0004] To change the bit, the ground in front of the drilling face had to be improved, and workers had to enter the chamber between the cutter and the bulkhead to change the bit manually. However, not only was the ground improvement process expensive and time-consuming, but transporting and fixing the heavy bit in a small space was hard, dangerous work. To avoid this, an intermediate shaft for bit replacement would be constructed, which could have a significant impact on securing land and construction costs.

[0005] Furthermore, when using mud shield tunneling machines under the riverbed or seabed, divers had to enter the chamber and replace the bit using high pressure. However, working under high pressure has time limitations and carries a high risk of decompression sickness, so bit replacement work increases costs and extends construction time.

[0006] Patent Document 1 discloses a cutter head that includes a rotating body attached to the front of the excavator body, spokes with mounting holes formed in the front part of the rotating body along the fore-and-aft direction, a leading bit attached to the mounting hole so that it can be moved freely and pulled out rearward, a fixing means for fixing the leading bit in a position where its tip protrudes from the front of the rotating body, and a valve plate in which the leading bit has a through hole that matches the mounting hole, and which moves while holding the leading bit when the leading bit is pulled out of the mounting hole to close the mounting hole, and which can be replaced with a new one when the leading bit wears out. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3692267 Summary of the Invention [Problem to be solved by the invention]

[0008] To replace a bit in a cutter head such as that described in Patent Document 1, an operator inside the excavator body enters the cutter spokes, loosens the bolts, and pulls the worn bit rearward from the mounting hole in the cutter spoke. He then rotates the valve plate to close the mounting hole and prevent muddy water and soil from entering, loosens the bolts, pulls out the cutting edge of the worn bit, replaces it with a new cutting edge, and moves it to the designated position and fixes it in place.

[0009] Thus, in order to replace a bit with the above-mentioned cutter head, the worker had to enter the narrow cutter spokes and move the heavy bit while loosening and tightening the bolts, and it was not possible to fully avoid the dangerous and heavy labor involved in replacing the bit.

[0010] The problem to be solved by the present invention is to provide a compact bit changing device that allows for easy and safe bit changing. Another object is to provide a bit changing device that can be remotely operated from outside the cutter spoke, eliminating the need for an operator to enter the cutter spoke for bit changing work. [Means for solving the problem]

[0011] The invention of claim 1 is a bit exchange device provided in a tunnel boring machine having a rotary head, comprising: a rotary base rotatably provided on the rotary head and having a plurality of bits that are provided so as to be able to protrude and retract from the rotary head; and retraction means fixed to the rotary head and configured to push and pull the bit, which has been positioned at a predetermined position by rotation of the rotary base, to protrude and retract from the rotary head, wherein the bit has a first engagement portion that can engage with the retraction means, and the retraction means has a second engagement portion that can engage with the first engagement portion, the first engagement portion engages with the second engagement portion to push and pull the bit, and the first engagement portion engages with the second engagement portion to disengage and engage with the second engagement portion by rotation of the rotary base.

[0012] The invention of claim 2 is the bit exchange device described in claim 1, characterized in that it comprises a reaction force receiver that receives a reaction force from the bit protruding from the rotating head, and a reaction force transmission member that transmits the reaction force from the bit to the reaction force receiver, and the reaction force transmission member is movable between a reaction force transmission position where it transmits the reaction force from the bit to the reaction force receiver, and a retracted position where it does not receive a reaction force from the bit.

[0013] The invention of claim 3 is a bit changing device as described in claim 1 or claim 2, characterized in that the protrusion of the bit from the rotating head by the retraction means is regulated so that it does not slide forward more than a predetermined amount.

[0014] The invention of claim 4 is a bit exchange device as described in claim 1 or claim 2, characterized in that the retraction of the bit from the rotating head by the retraction means is regulated so that it does not slide rearward more than a predetermined distance.

[0015] The invention according to claim 5 is the bit exchange device according to claim 1 or 2, characterized in that rotation of the bit with respect to the rotary base is restricted.

[0016] The invention of claim 6 is a bit exchange device as described in claim 1 or claim 2, characterized in that among the multiple bits provided on the rotating base, a pair of bits are arranged at the predetermined position, which is a position aligned circumferentially around the rotating head, and by rotating the rotating base, another pair of bits is arranged at the predetermined position.

[0017] The invention of claim 7 is a bit exchange device as described in claim 1 or claim 2, characterized in that it further comprises a bit forward / backward movement prevention means that prevents the bit from moving forward / backward relative to the rotating base when the first engagement portion and the second engagement portion are disengaged due to rotation of the rotating base.

[0018] The invention of claim 8 is a bit changing device as described in claim 7, characterized in that the bit forward / backward movement prevention means is fixed to the rotating head and has a third engagement portion that can engage with the first engagement portion when the first engagement portion and the second engagement portion are disengaged. [Effects of the Invention]

[0019] According to the present invention, when a bit becomes worn and shortened or is damaged, it can be easily and safely replaced with a new bit without the need for an operator to approach the bit and manually replace it. In addition, the operation of the bit replacement device can be remotely controlled from outside the cutter spoke, allowing for safe bit replacement without the operator having to enter the cutter spoke to perform the bit replacement work. Furthermore, since the first engagement portion of the bit and the second engagement portion of the retraction means are engaged and disengaged by rotation of the rotating base, there is no need to move the retraction means in the direction of the bit's extension and retraction to engage and disengage the first engagement portion and the second engagement portion, which allows the depth dimension of the device to be small.

[0020] In addition, by providing a reaction force receiver that receives the reaction force from the bit protruding from the rotating head and a reaction force transmission member that transmits the reaction force to the reaction force receiver, even if the bit is subjected to pressure from the ground during drilling, the reaction force from the bit is supported by the reaction force receiver transmitted via the reaction force transmission member, and is not transmitted directly to the retraction means, reducing the burden on the mechanism that drives the retraction means and allowing for stable drilling using the bit. Furthermore, by making the reaction force transmission member movable between the reaction force transmission position and the retracted position, the reaction force transmission member does not get in the way when pushing or pulling the bit.

[0021] In addition, the protrusion of the bit from the rotating head by the retraction means is restricted so that it does not slide forward more than a certain amount, so the bit does not escape forward of the rotating head and the load on the retraction means can be reduced.

[0022] In addition, the insertion of the bit into the rotating head by the retraction means is restricted so that it does not slide rearward more than a certain amount, so the bit will not slip out behind the rotating head and the load on the retraction means can be reduced.

[0023] In addition, since the rotation of the bit relative to the rotating base is restricted, the bit does not rotate during drilling, and the bit does not rotate when the rotating base rotates, so the first engagement and second engagement portions engage smoothly.

[0024] In addition, when a pair of bits are positioned in circumferentially aligned positions on the rotary head and the rotary base rotates to position another pair of bits in a predetermined position, drilling can be performed by rotating the rotary head in either a clockwise or counterclockwise direction, and a new bit can be positioned in the same predetermined position by rotating the rotary base.

[0025] In addition, the bit forward / backward movement prevention means can prevent the bit from moving forward / backward relative to the rotating base when the first engagement portion and the second engagement portion are disengaged due to rotation of the rotating base. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 2 is a front view of the rotary head of the tunnel boring machine according to the embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a cutter spoke according to an embodiment of the present invention. [Figure 3] 1 is a perspective view of a bit exchanging device showing an embodiment of the present invention. [Figure 4] FIG. 2 is an exploded perspective view of a bit and a retractable means according to an embodiment of the present invention. [Figure 5] 1 is a cross-sectional view of a bit exchanging device showing an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view of a bit exchange device illustrating a bit exchange process. [Figure 7] 1 is a cross-sectional view of a bit exchange device illustrating a bit exchange process. [Figure 8] 1 is a cross-sectional view of a bit exchange device illustrating a bit exchange process. [Figure 9] 1 is a cross-sectional view of a bit exchange device illustrating a bit exchange process. [Figure 10] FIG. 2 is a perspective view of a bit forward / backward movement prevention tool of the bit changing device according to the present embodiment. [Figure 11] 10 is a cross-sectional view of a bit exchanging device illustrating a bit exchanging process in a modified example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. It goes without saying that the present invention is not limited to the embodiments.

[0028] Figure 1 is a front view of the rotary head, Figure 2 is an oblique view of the cutter spokes, Figure 3 is an oblique view of the bit changing device, Figure 4 is an exploded oblique view of the bit and the retraction means, Figure 5 is a cross-sectional view of the bit changing device, Figures 6 to 9 are cross-sectional views of the bit changing device explaining the bit changing process, and Figure 10 is an oblique view of the bit forward / backward movement prevention device.

[0029] As shown in FIG. 1, the tunnel boring machine according to this embodiment is a shield machine 1. The shield tunneling machine 1 has a circular rotating head 2 on its front end face, and by rotating the rotating head 2 around the central axis of the shield tunneling machine 1, it moves forward while excavating the ground with a bit 30 protruding from the front of the rotating head 2.

[0030] The rotating head 2 can rotate both clockwise and counterclockwise. The rotary head 2 has four cutter spokes 21 and a cutter ring 22 arranged at equal intervals radially from the center of rotation.

[0031] The cutter spoke 21 is a hollow tube, and as shown in FIGS. 1 and 2, a plurality of circular holes 210 are drilled in the front plate thereof and aligned in the axial direction to accommodate the bit changer 3 therein.

[0032] Four circular holes 210 are provided in each cutter spoke 21, and each accommodates a bit changer 3. The bit exchange device 3 is a device for exchanging worn or damaged bits 30. The bit 30 is a bit provided in a normal shield tunneling machine for excavating the natural ground, that is, a so-called main bit.

[0033] As shown in FIG. 2, the bit exchange device 3 is provided with four bits 30 a , 30 b , 30 c , and 30 d that are retractable from a rotary base 31 housed in a circular hole 210 .

[0034] In FIG. 2, the bits 30a and 30c are arranged so as to face each other in the circumferential direction of the rotation of the rotary head 2 (cutter spokes 21), and are arranged in a state of protruding from the front plate of the cutter spokes 21.

[0035] In FIG. 2, the bits 30b and 30d are arranged so as to face each other in the radial direction of the rotation of the rotary head 2 (cutter spokes 21), and are arranged in a state where they are recessed from the front plate of the cutter spokes 21.

[0036] In this state, the rotary head 2 (cutter spokes 21) rotates, so that the bits 30a and 30c excavate the natural ground, while the bits 30b and 30d do not excavate the natural ground.

[0037] As shown in FIG. 3, the bit exchanging device 3 includes a rotary base 31 on which the bits 30a to 30d are provided so as to be able to protrude and retract, and a vertical jack 32 which is retracting means for pushing and pulling the bits 30a to 30d to protrude and retract.

[0038] The rotating base 31 is disk-shaped and has approximately the same shape as the circular hole 210 formed in the cutter spoke 21 of the rotating head 2, and is rotatably fitted into the circular hole 210 so that the front surface of the rotating base 31 is flush with the front surface of the cutter spoke 21 (Figure 2). In order to prevent water and earth and sand from entering the cutter spokes 21 from the natural ground, a seal material may be provided on the sliding surface between the outer periphery of the rotary base 31 and the circular hole 210.

[0039] A small-diameter portion 310 having a circular cross section is integrally formed on the rear surface of the center of the rotary base 31 so as to protrude, and a rotary shaft 311 extends along the central axis from the rear surface of the small-diameter portion 310. The rotary shaft 311 is connected to an actuator such as a motor and gear (not shown), and when driven by the actuator, the rotary base 31 rotates relative to the cutter spokes 21. A mechanism for rotating a rotor provided on the cutter spokes 21 in this way is known, as exemplified in Japanese Patent Application Laid-Open No. 2007-327264, and therefore a detailed description thereof will be omitted.

[0040] The rotary base 31 has four circular through-holes 312 formed at equal intervals in the circumferential direction, penetrating the rotary base 31 in the front-rear direction.

[0041] Of the four through holes 312, a pair of through holes 312 facing the center of rotation (the through holes in which bits 30a and 30c are arranged in Figure 3) are arranged side by side in the circumferential direction (rotation direction) of the rotating head 2, and by rotating the rotating base 31 by 90 degrees by driving the motor, the other pair of through holes 312 (the through holes in which bits 30b and 30d are arranged in Figure 3) are arranged side by side in the circumferential direction of the rotating head 2.

[0042] Bits 30a to 30d are provided in the through holes 312 so as to be able to protrude from and retract into the front surface of the cutter spoke 21, respectively. The bit 30 has a base portion 300 and a cutting edge portion 301. For convenience, the bit 30a will be described in Fig. 4, but the other bits 30b, 30c, and 30d are similar and therefore will not be described again.

[0043] The base portion 300 has a cylindrical cross section that is substantially the same shape as the through-hole 312 of the rotary base 31, and is fitted into the through-hole 312 so as to be slidable in the front-rear direction. In order to prevent water and earth and sand from entering the cutter spokes 21 from the natural ground, a seal material may be provided on the sliding surface between the outer periphery of the base portion 300 and the through-hole 312. At the rear of the outer circumferential surface of the base 300, a protrusion 302 is formed along the front-rear direction at a position facing the center of the rotary base 31.

[0044] A first engagement portion 303 is formed on the rear surface of the base portion 300 . The first engagement portion 303 is formed along the circumferential direction of the base portion 300 and has a slit portion 3030 that is open at both ends, and a wide groove 3031 that is formed continuously with the inner end of the slit portion 3030.

[0045] The blade portion 301 is integrally provided on the front surface of the base portion 300 and is installed so that the cutting surface faces the outer peripheral surface of the rotary base 31 .

[0046] As shown in FIG. 5, guide grooves 313 that slidably engage with the protrusions 302 of the bits 30a to 30d are formed on the outer circumferential surface of the small diameter portion 310 of the rotary base 31 at positions facing the through holes 312 (base portions 300).

[0047] As shown in FIG. 6, a fall prevention cover 314 is placed on the rear surface of the small diameter portion 310, and the rear end of the guide groove 313 is closed by the fall prevention cover 314.

[0048] The protrusions 302 of the bits 30a to 30d are slidably engaged with the guide grooves 313 formed in the small diameter portions 310, so that the rotation of the bits 30 relative to the rotary base 31 is restricted, but the bits 30 can slide in the forward and backward directions.

[0049] When the protrusions 302 of the bits 30a to 30d reach the front end of the guide groove 313 (the rear surface of the rotating base 31), the guide groove 313 disappears and becomes a step, and the protrusions 302 come into contact with the step, restricting the forward sliding of the bits 30a to 30d, so that the bits 30a to 30d do not escape to the front of the rotating base 31. In this position, the cutting edges 301 of the bits 30a to 30d protrude from the front surface of the rotary base 31 (the front surface of the rotary head 2).

[0050] When the protrusions 302 of the bits 30a to 30d reach the rear ends of the guide grooves 313 and hit the fall prevention lids 314, the backward sliding of the bits 30a to 30d is restricted, so that the bits 30a to 30d do not fall backward of the rotary base 31. At this position, the cutting edges 301 of the bits 30a to 30d are inserted into the through holes 312 of the rotary base 31.

[0051] The vertical jack 32 is fixed inside the cutter spoke 21 of the rotating head 2 via a bracket or the like, and is installed on each rotating base 31 behind a pair of through holes 312 arranged side by side around the circumference of the rotating head 2.

[0052] As shown in FIG. 4, the vertical jack 32 includes a cylinder 320, a rod 321, and a second engagement portion 322 attached to the front end surface of the rod 321.

[0053] The rear of the cylinder 320 is connected to a hydraulic device (not shown), and by driving the hydraulic device, the rod 321 extends or retracts forward from the front surface of the cylinder 320 .

[0054] The second engagement portion 322 is engageable with the first engagement portion 303 of the bit 30a, and has a vertical shaft portion 3220 that slidably engages with the slit portion 3030 of the first engagement portion 303, and a horizontal shaft portion 3221 that is arranged perpendicular to the front end of the vertical shaft portion 3220 and slidably engages with the wide groove 3031 of the first engagement portion 303.

[0055] The first engagement portion 303 of the bit 30a, which rotates together with the rotating base 31, is formed along the circumferential direction of the rotating base 31, and the second engagement portion 322 of the vertical jack 32, which is fixed to the rotating head 2, can slide and engage with the first engagement portion 303.Therefore, the first engagement portion 303 of the bit 30a and the second engagement portion 322 of the vertical jack 32 can be disengaged from each other simply by rotating the rotating base 31 relative to the rotating head 2 while keeping the rod 321 of the vertical jack 32 stationary without moving it back and forth. When the bit 30 moves with the rotation of the rotary base 31 and the first engagement portion 303 slides against the second engagement portion 322, if the rod 321 rotates relative to the cylinder 320, the horizontal shaft portion 3221 of the second engagement portion 322 may come out of the wide groove 3031 of the first engagement portion 303. In such a case, the horizontal shaft portion 3221 of the second engagement portion 322 may be formed in a shape, for example, a disk shape, so that it does not come out of the wide groove 3031 of the first engagement portion 303 even when the rod 321 rotates and maintains the engagement.

[0056] Then, when the first engagement portion 303 of the bit 30a and the second engagement portion 322 of the vertical jack 32 are engaged and the rod 321 of the vertical jack 32 is extended, the blade portion 301 of the bit 30 protrudes from the front surface of the rotating base 31 (the front surface of the rotating head 2). When the rotary head 2 is rotated in this state, the pair of bits 30 arranged in the circumferential direction of the rotary head 2 can excavate the natural ground.

[0057] On the other hand, when the rod 321 of the vertical jack 32 is retracted, the cutting edge 301 of the bit 30 a is inserted into the through-hole 312 of the rotary base 31 . At this time, the wide groove 3031 formed at the inner end of the first engagement portion 303 and the horizontal shaft portion 3221 formed at the tip of the second engagement portion 322 are engaged, so the engagement between the first engagement portion 303 and the second engagement portion 322 does not come off, and the height can be matched with other bits.

[0058] When the natural ground is excavated using the bit 30 (bits 30a and 30c in this embodiment) pushed out by the vertical jack 32, the bit 30 is pushed back by the force applied by the natural ground, placing a large load on the drive mechanism of the vertical jack 32, which can easily cause the bit 30 to be pushed in or become unstable. Furthermore, even if the drive mechanism is hydraulically driven or otherwise provided with sufficient output, having hydraulic pressure constantly applied is a waste of power. Therefore, it is desirable to maintain the pushed-out state using another method.

[0059] For this reason, as shown in Figures 3 and 4, a reaction force receiver 33 is provided to receive the reaction force from the bit 30 that protrudes from the rotary head 2 and performs drilling, and a reaction force transmission member 34 is provided to transmit the reaction force from the bit 30 to the reaction force receiver 33.

[0060] The reaction force receiver 33 is fixed inside the cutter spokes 21 of the rotary head 2. The reaction force receiver 33 is formed in a columnar shape having a semicircular inner peripheral surface 331 in cross section, and is arranged so that the outer peripheral surface of the cylinder 320 of the vertical jack 32 fits along this inner peripheral surface 331.

[0061] The reaction force receiver 33 is disposed on the outer periphery of the rotary base 31 so as not to hinder the movement of the rotary shaft 311 of the rotary base 31. The reaction force receiver 33 is disposed rearward of the front end surface of the cylinder 320. The front end surface of the reaction force receiver 33 is a reaction force receiving surface 330 , and the reaction force receiving surface 330 is provided flush with the front end surface of the cylinder 320 .

[0062] The reaction force transmission member 34 is disposed so as to surround the extended rod 321 of the vertical jack 32 from the outer periphery of the rotary base 31, and a recess 340 wider than the diameter of the rod 321 of the vertical jack 32 is formed on the inner periphery. The longitudinal dimension of the reaction force transmission member 34 is set equal to the distance from the rear surface of the bit 30 protruding from the rotary head 2 to the reaction force receiving surface 330 of the reaction force receiver 33 .

[0063] A pushing / pulling device such as a hydraulic jack (not shown) is connected to the outer surface of the reaction force transmission member 34, and by driving the pushing / pulling device, the reaction force transmission member 34 moves in the radial direction of the rotary base 31.

[0064] When the reaction force transmission member 34 is pushed toward the center of the rotating base 31 while the bit 30 protrudes from the rotary head 2, the reaction force transmission member 34 is positioned at a reaction force transmission position between the reaction force receiving surface 330 of the reaction force receiver 33 and the rear surface of the bit 30, and transmits the reaction force from the bit 30 to the reaction force receiver 33. Therefore, no reaction force from the bit 30 is applied to the vertical jack 32.

[0065] When the reaction force transmission member 34 is pulled radially outward from the rotary base 31 , the reaction force transmission member 34 moves to a retracted position outside the outer periphery of the rotary base 31 where it does not receive a reaction force from the bit 30 . At this time, since the reaction force transmission member 34 is not positioned behind the bit 30 , the bit 30 can be pulled down by the vertical jack 32 and immersed in the through-hole 312 .

[0066] The process of exchanging the bit 30 using the bit exchange device will be described below.

[0067] During excavation by the shield tunneling machine 1, as shown in Figure 6, the first engagement portion 303 of a pair of bits 30a, 30c arranged side by side circumferentially of the rotary head 2 engages with the second engagement portion 322 of the vertical jack 32, and the rod 321 is extended so that the bits 30a, 30c protrude.

[0068] At this time, the protrusions 302 of the bits 30a, 30c come into contact with the front ends of the guide grooves 313 formed in the small diameter portion 310 of the rotary base 31, restricting the bits 30a, 30c from sliding forward. In other words, the protrusion of the bits 30a, 30c from the rotary head 2 by the vertical jack 32 (protruding and retracting means) is restricted so that they do not slide forward more than a predetermined distance.

[0069] Furthermore, the reaction force transmission member 34 is moved toward the center of the rotary base 31 and positioned at the reaction force transmission position directly behind the bits 30a and 30c, and the reaction force from the bits 30a and 30c is transmitted to the reaction force receiver 33.

[0070] If the bits 30a, 30c become worn or damaged due to drilling, as shown in Figure 7, the reaction force transmission member 34 is moved outward from the center of the rotating base 31 to a retracted position directly behind the bits 30a, 30c, and the rod 321 of the vertical jack 32 is retracted to immerse the bits 30a, 30c in the through hole 312 of the rotating base 31.

[0071] At this time, the protrusions 302 of the bits 30a and 30c come into contact with the fall prevention cover 314, restricting the backward sliding of the bits 30. In other words, the vertical jack 32 (retractable means) restricts the immersion of the bits 30a and 30c into the rotary head 2 so that they do not slide backward more than a predetermined distance.

[0072] Next, the rotary base 31 is rotated 90 degrees together with the bits 30a to 30d arranged in the through-holes 312. Even when the rotary base 31 and the bits 30a to 30d rotate, the vertical jack 32 is fixed inside the cutter spokes 21 with the rod 321 retracted and does not rotate together with the rotary base 31. Therefore, the first engagement portions 303 of the bits 30a and 30c slide relative to the second engagement portions 322 of the vertical jack 32, and the first engagement portions 303 are disengaged from the second engagement portions 322 of the rod 321.

[0073] Then, as shown in Figure 8, when the rotating base 31 rotates 90 degrees, another pair of bits 30b, 30d are arranged side by side in the circumferential direction of the rotating head 2, and the first engagement portions 303 of these bits 30b, 30d engage with the second engagement portions 322 of the rod 321.

[0074] Next, as shown in Figure 9, the rod 321 of the vertical jack 32 is extended to cause a new pair of bits 30b, 30d to protrude from the rotating base 31, and then the reaction force transmission member 34 is moved toward the center of the rotating base 31 to the reaction force transmission position.

[0075] In this manner, worn or broken bits 30a, 30c are replaced with new bits 30b, 30d. The operation of these bit changing devices 3 can be performed remotely from outside the cutter spoke 21, which allows for safe bit changing work without the need for an operator to enter the inside of the cutter spoke 21 to perform the bit changing work.

[0076] When the rotating base 31 is rotated together with the bits 30a to 30d, the bits 30a to 30d move between the pair of vertical jacks 32, i.e., the first engagement portion 303 of the bits 30a to 30d disengages from the second engagement portion 322 of the vertical jack 32. However, in this embodiment, in order to prevent the bits 30a to 30d from moving in the front-to-rear direction, particularly forward, relative to the rotating base 31 during this period, the outer diameter of the base portion 300 of the bits 30a to 30d and the inner diameter of each through hole 312 of the rotating base 31 are set to dimensions such that the base portion 300 is stopped in an engaged state just fitted into the through hole 312 without moving even with a force less than that applied by the vertical jack 32.

[0077] However, a structure may be separately provided in the bit exchange device 3 to reliably prevent the bits 30a to 30d from moving in the forward and backward directions relative to the rotary base 31 when the bits 30a to 30d move between the pair of vertical jacks 32.

[0078] For example, a bit forward / backward movement prevention device 42 as shown in FIG. 10 may be disposed between a pair of vertical jacks 32 on the trajectory along which the first engagement portions 303 of the bits 30a to 30d are moved by the rotary base 31.

[0079] The bit forward / backward movement prevention device 42 includes a base portion 420 and a third engagement portion 421. The base 420 has, for example, a cylindrical shape similar to the cylinder 320 of the vertical jack 32, and the other end opposite to the one end where the third engagement portion 421 is provided is fixed inside the cutter spoke 21 via a bracket or the like. Although the base 420 has been described as having a cylindrical shape, the shape is not limited to this and may be rectangular or may have an arc shape that resembles the trajectory of the bit 30 moving as the rotary base 31 rotates in an overall view. In addition, one or more bit forward / backward movement prevention devices 42 may be provided between the pair of vertical jacks 32.

[0080] A third engagement portion 421 is provided at one end of the base portion 420. The third engagement portion 421 has a T-shaped cross-sectional shape similar to the second engagement portion 322 of the vertical jack 32, and is formed so that the cross-sectional shape is positioned along the trajectory (arc) along which the first engagement portion 303 of the bits 30a to 30d moves as the rotating base 31 rotates, and has a cross-sectional shape that can engage with the first engagement portion 303 of the bits 30a to 30d.

[0081] The third engagement portion 421 has a vertical shaft portion 4210 that slidably engages with the slit portion 3030 of the first engagement portion 303, and a horizontal shaft portion 4211 that is arranged perpendicular to the front end of the vertical shaft portion 4210 and slidably engages with the wide groove 3031 of the first engagement portion 303.

[0082] The first engagement portions 303 of the bits 30a to 30d, which rotate together with the rotating base 31, are formed along the circumferential direction of the rotating base 31, and the third engagement portion 421 of the bit forward / backward movement prevention device 42, which is fixed to the rotating head 2 between a pair of vertical jacks 32, can slide and engage with the first engagement portion 303.Therefore, even when the first engagement portion 303 and the second engagement portion 322 are disengaged between the pair of vertical jacks 32 during rotation of the rotating base 31, the bits 30a to 30d can be prevented from moving forward / backward relative to the rotating base 31, and the first engagement portions 303 of the bits 30a to 30d can be engaged with the second engagement portion 322 of the vertical jack 32.

[0083] [Other Modifications] The present invention is not limited to the above-described embodiment, and may also include the following, for example.

[0084] In this embodiment, the tunnel boring machine is a shield machine, but is not limited to this as long as it has a rotary head. For example, it may be a tunnel boring machine such as a jacking excavator or a TBM (tunnel boring machine).

[0085] In this embodiment, four bits are provided on one rotary base, but the number of bits can be changed as appropriate. Also, although a pair of bits are replaced at the same time, they can also be replaced one by one.

[0086] In this embodiment, the bit changer 3 is provided on the cutter spokes 21 of the rotary head 2, but this is not limiting, and the bit changer may be provided on the face plate of a rotary head that has a face plate.

[0087] In this embodiment, the reaction force receiver 33 is configured as a separate member from the cylinder 320, but the cylinder 320 may be configured to have the function of the reaction force receiver 33 by configuring them as an integral part. As a specific example, as shown in Fig. 11, instead of providing the reaction force receiver 33 as a separate member, the cylinder 320 may be configured to directly receive the force from the reaction force transmitting member 34 that has moved to the reaction force transmitting position. In this case, the front end surface of the cylinder 320 serves as the reaction force receiving surface, and the cylinder 320 of the vertical jack 32 corresponds to the reaction force receiver of the present invention.

[0088] In this embodiment, the bits 30a to 30d to be replaced in the bit exchange device are so-called main bits, which are bits that are installed in a normal shield tunneling machine and used to excavate natural ground, but this is not limited to this. For example, they may be leading bits or roller bits. In this case, the leading bits or roller bits may be configured to be retractable and retractable on a rotating base. Furthermore, in this embodiment, in the bit changing device, the bits 30a to 30d to be changed are positioned directly facing the face, but the device may also be applied to bits that are positioned facing further outward, such as so-called outermost bits or overcutters.

[0089] Each technical matter in any of the embodiments including the modified examples may be applied to other embodiments to be used as examples. [Explanation of symbols]

[0090] 1. Shield tunneling machine 2 rotating heads 21 Cutter Spoke 210 circular hole 22 Cutter Ring 3-bit switching device 30-bit 300 Base 301 Blade part 302 Projection 303 First engagement part 3030 Slit section 3031 Wide groove 31 Rotating base 310 Small diameter section 311 Rotation axis 312 Through hole 313 Guide groove 314 Fall prevention lid 32 Vertical jack (means of emergence) 320 cylinders 321 Rod 322 Second engagement portion 3220 Vertical shaft 3221 Horizontal shaft 33 Reaction receiver 330 Reaction surface 331 Inner surface 34 Reaction force transmission member 340 recess 42 Bit forward / backward movement prevention device 420 base 421 Third engagement part 4210 Vertical shaft 4211 Horizontal shaft

Claims

1. A bit changing device provided on a tunnel boring machine having a rotary head, a rotary base rotatably mounted on the rotary head and having a plurality of bits that are retractable from the rotary head; and a retraction means that is fixed to the rotary head and that pushes and pulls the bit, which is positioned at a predetermined position by rotation of the rotary base, to retract and protrude from the rotary head, the bit has a first engaging portion that can be engaged with the retractable means, the retractable means has a second engaging portion engageable with the first engaging portion, and the first engaging portion and the second engaging portion are engaged with each other to push and pull the bit; The first engaging portion and the second engaging portion are engaged and disengaged by rotation of the rotary base. A bit exchange device characterized by:

2. a reaction force receiver that receives a reaction force from the bit protruding from the rotary head; a reaction force transmission member that transmits a reaction force from the bit to the reaction force receiver, The reaction force transmission member is movable between a reaction force transmission position where the reaction force is transmitted from the bit to the reaction force receiver and a retracted position where the reaction force is not received from the bit.

2. The bit exchange device according to claim 1.

3. The projection of the bit from the rotary head by the retractable means is restricted so as not to slide forward more than a predetermined distance.

3. The bit exchange device according to claim 1 or 2.

4. The retraction of the bit from the rotary head by the retraction means is restricted so that it does not slide rearward beyond a predetermined distance.

3. The bit exchange device according to claim 1 or 2.

5. The rotation of the bit relative to the rotary base is restricted.

3. The bit exchange device according to claim 1 or 2.

6. Among the plurality of bits provided on the rotary base, a pair of bits is arranged at the predetermined positions aligned in the circumferential direction of the rotary head, and by rotating the rotary base, another pair of bits is arranged at the predetermined positions.

3. The bit exchange device according to claim 1 or 2.

7. The tool further includes a bit forward / backward movement prevention means for preventing the bit from moving forward / backward relative to the rotary base when the first engaging portion and the second engaging portion are disengaged due to rotation of the rotary base.

3. The bit exchange device according to claim 1 or 2.

8. The bit forward / backward movement prevention means is fixed to the rotary head and includes a third engaging portion that can engage with the first engaging portion when the first engaging portion and the second engaging portion are disengaged from each other.

8. The bit exchange device according to claim 7.

Images