JP2006299667A - Bit replenishing mechanism and tunnel excavator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely replenish a bit with a simple constitution, without having adverse influence on an excavation mechanism. <P>SOLUTION: The replenishing bit 25 is made to stand by in an inner peripheral part of a cutter head 4 having the required number of bits, and only the replenishing bit 25 standing by in the inner peripheral part of the cutter head 4 is made movable to an outer peripheral part to the cutter head 4 in response to abrasion of the bits. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tunnel excavator used for a shield method, a mountain method, a propulsion method, and the like, and a bit replenishment mechanism used for the tunnel excavator.

  The tunnel excavator includes a shield machine used for the shield method, a tunnel boring machine (TBM) used for the mountain method, and a propulsion machine used for the propulsion method. For example, a shield machine (shield machine) is designed to excavate natural ground by rotating a cutter head attached to the tip of a cylindrical shield body via a center shaft and build a tunnel. is there. Note that the cutter head includes a substantially disc-shaped cutter face and a substantially radial cutter pork.

  A plurality of types of bits (excavating teeth) having different functions, applications, shapes and structures, such as a tooth bit, a leading bit, and a shell bit, are attached to the cutter head. In the usual case, the bit is fixed directly to the cutter head by welding, or is fixed using a bracket and a bolt.

  In such a shield machine, as the excavation distance becomes longer, it is necessary to replace the worn bit on the way.

  As a means for exchanging the bit, conventionally, the cutter head is taken into the shield body and the bit is exchanged in the shield body, or formed between the back surface of the cutter head and the tip of the shield body. An operator enters the chamber and manually replaces the bit (cuts the worn bit and re-welds the new bit if welding is fixed, removes the worn bit and removes the new bit if bolted. There was something to fasten and fix.

  However, when the cutter head is taken into the shield body, the apparatus configuration becomes large, so that the manufacturing cost of the shield machine increases, and the process and work period for exchanging the bits are also increased.

  In addition, when an operator goes out to the chamber, which is the most proven means, and replaces the bit manually, the bit replacement position is determined in advance, and the location is stabilized and improved from the ground. After entering the shield machine and stopping it, it is necessary for the worker to go out to the chamber and work, etc., but the work environment in the chamber, the risk of collapse of the ground, work on the ground improvement site There are various problems such as securing the belt and increasing the construction cost due to the decrease in the excavation speed on the improved ground. In addition, there is a concern that the exchangeable bits are limited, and that when the cutter head is a spoke type, the cutout pork is enormous and the drilling mechanism is adversely affected.

Therefore, in order to solve such a problem, it is desired to develop a mechanism capable of easily exchanging bits. As such, a cutter row that is movably provided with respect to the cutter pork can be exchanged by taking it into the shield body via the center shaft (Patent Document 1), or a cutter having a half length. There is a type in which a spoke is provided so as to be freely extendable and a bit is moved together with a cutter pork from an inner excavation position to an outer excavation position (Patent Document 2).
JP 2004-19337 A JP 2004-27523 A

  However, in Patent Document 1, since the cutter row is taken into the shield body via the center shaft and the cutter row is exchanged in the shield body, the center shaft is thickened or replaced within the shield body. The problem that the equipment configuration becomes large, such as the need to secure space, has not yet been solved, and there has been a problem that a separate storage place for worn cutter rows or new cutter rows is required. .

  Moreover, since the thing of the patent document 2 needs to provide the cut-spoke which has a half length specially, it invites the reduction of the space which provides a normal cut-spoke, and is structurally disadvantageous, and also has a half length. As the overall structure of the katspoke is made to expand and contract, the structure of this katspoke becomes complicated and large in order to incorporate an expansion / contraction mechanism into the katspoke and improve the strength accompanying expansion / contraction. There was a problem that reinforcement measures were required.

  In order to solve the above-mentioned problem, in the invention described in claim 1, a refilling bit is made to wait on the inner periphery of a cutter head having a required number of bits, and the cutter head is It is characterized by a bit replenishing mechanism and a tunnel excavator configured such that only a refilling bit waiting at the inner peripheral portion can be moved to the outer peripheral portion with respect to the cutter head.

  According to a second aspect of the present invention, a plurality of replenishing bits are arranged in a belt shape to form a replenishing bit string, and a moving groove extending from the inner periphery to the outer periphery is formed in the cutter head, so that the replenishment is performed. The bit replenishing mechanism and the tunnel excavator according to claim 1, wherein the bit train is configured to be movable from the inner peripheral portion to the outer peripheral portion of the cutter head along the moving groove portion.

  In the third aspect of the present invention, the inner peripheral portion of the moving groove is formed deeper than the outer peripheral portion, and the replenishing bit before moving is pulled in more than the other bits. A bit replenishing mechanism and a tunnel excavator according to claim 2 that are capable of waiting.

  According to the fourth aspect of the present invention, the moving groove portion extends to the end portion on the outer peripheral portion side of the cutter head, and the outermost peripheral bit is provided at the end portion on the outer peripheral portion side of the replenishing bit row, so that the replenishing bit row is provided. 4. A bit replenishing mechanism and a tunnel excavator according to claim 2 or 3, wherein the outermost peripheral bit can appear on the outer peripheral portion of the cutter head after the movement of.

  The invention described in claim 5 is characterized by a tunnel excavator provided with the bit replenishment mechanism according to any one of claims 1 to 4.

  According to the first aspect of the present invention, the replenishment bit is made to wait on the inner peripheral portion of the cutter head having the required number of bits, and the replenishment that has been waiting on the inner peripheral portion of the cutter head in accordance with wear of the bit. Since only the working bit can be moved to the outer peripheral portion with respect to the cutter head, it becomes possible to replenish the replenishing bit to the outer peripheral portion of the cutter head when the outer peripheral bit is worn. In addition, the inner peripheral part of the cutter head has a short moving distance and the original bit and the replenishing bit are doubled, so there is less wear compared with the bit on the outer peripheral part. Both the replenishment bit is in a state of being preserved. Therefore, excavation can be continued without any trouble even after the refilling bit is moved to the outer peripheral portion. In addition, since only the refilling bit is moved from the inner periphery to the outer periphery with respect to the cutter head, it can be applied almost as it is to a normal cutter head, and it does not adversely affect the excavation mechanism. Bit replenishment can be reliably performed with a simple configuration. In addition, since bit replenishment is possible at any time, it is possible to eliminate the need to specify the location and timing of bit replenishment. In addition, since ground improvement from the ground becomes unnecessary, it is freed from various limitations associated therewith, and the burden can be greatly reduced in terms of construction period and cost.

  According to a second aspect of the present invention, a plurality of replenishing bits are arranged in a belt shape to form a replenishing bit string, and a moving groove extending from the inner peripheral portion to the outer peripheral portion is formed in the cutter head, whereby the replenishing bit is formed. Since the bit string is configured to be movable from the inner peripheral portion to the outer peripheral portion of the cutter head along the moving groove portion, it is possible to realize a mechanism for quickly replenishing bits with a simple configuration and a minimum space. Moreover, since the replenishment bit can be placed on the cutter head throughout, there is no need to attach / remove / store / recover the replenishment bit. A storage mechanism / recovery mechanism is also unnecessary.

  According to the third aspect of the present invention, the inner groove portion of the moving groove is formed deeper than the outer peripheral portion, and the refilling bit before moving is in a state of being pulled in more than the other bits. By doing so, it becomes difficult for the replenishing bit to be exposed to the excavated gap during standby, so wear of the replenishing bit before movement can be minimized.

  According to the invention of claim 4, the moving groove is extended to the end on the outer peripheral side of the cutter head, and the outermost peripheral bit is provided at the end on the outer peripheral side of the replenishing bit string. Since the outermost peripheral bit can appear on the outer peripheral portion of the cutter head after the movement, the outermost peripheral bit can be replenished.

  According to invention of Claim 5, the tunnel excavator which has the same effect as the bit replenishment mechanism of any one of Claim 1 thru | or 4 can be obtained.

  The purpose of ensuring that the bit can be replenished with a simple configuration without adversely affecting the excavation mechanism is to wait for the replenishment bit on the inner periphery of the cutter head having the required number of bits. This is realized by means that only the replenishment bit waiting on the inner peripheral portion of the cutter head is movable to the outer peripheral portion with respect to the cutter head with wear.

  Hereinafter, embodiments embodying the present invention will be described together with illustrated examples.

  1 to 13 show an embodiment of the present invention.

  First, the configuration will be described. The tunnel excavator 1 includes a shield machine used for the shield method, a tunnel boring machine (TBM) used for the mountain method, and a propulsion machine used for the propulsion method. For example, the shield machine 2 (shield machine) excavates inside the shield body 3 while excavating a natural ground by rotating a cutter head 4 attached to the tip of a cylindrical shield body 3 (see FIG. 3). A tunnel or the like is constructed by assembling a segment (lining body) to be an inner wall of a mine and propelling the shield body 3 while supporting the reaction force on the segment. Usually, the shield body 3 has a cylindrical shape, and the cutter head 4 is rotated about a center shaft 5 provided on the axis of the shield body 3 as a rotation center. Correspondingly, the cutter head 4 having a shape corresponding to the circular shape at the tip of the shield body 3 is attached. For example, the cutter head 4 includes a disk-like cutter face 6 and a radial cutter pork. In this embodiment, the cutter face 6 is used, but a cutter pork may be used. A chamber 7 called an earth pressure chamber or the like is formed between the back surface of the cutter face 6 and a hood portion 3a and a pressure partition 3b provided at the tip of the shield body 3.

  As shown in FIG. 1, a leading bit 11 for improving the excavability of other bits and preventing these wears as well as leading bits are provided on the front surface of the cutter head 4 as shown in FIG. 11 such as a tooth bit 12 (or main bit) for excavating a natural ground loosened at 11 and an outer peripheral bit 13 or an outermost peripheral bit especially provided at the outermost peripheral portion of the front surface of the cutter head 4, functions, applications, shapes, structures, etc. A plurality of types of bits (excavating teeth) with different sizes are attached. There are various types of outermost peripheral bits having different functions, applications, shapes and structures, such as shell bits, trim bits and gauge bits.

  A center member 21 such as a fish tail or a center cone is attached to the center of rotation of the cutter head 4. A plurality of the above-described types of bits are arranged, for example, radially, annularly, or spirally with respect to the rotation center of the cutter head 4. Each type of bit described above is normally a fixed bit fixed to the cutter head 4.

  In general, when the cutter head 4 is the cutter face 6, a strip-like or slit-like earth / sand intake port 22 extending in the radial direction of the cutter head 4 (or the shield body 3) is formed. A plurality of pairs of teeth bits 12 are arranged substantially opposite to each other along both sides. In FIG. 1, reference numeral 23 denotes a copy cutter attached to the outer surface of the cutter head 4. The copy cutter 23 is a movable bit that can be protruded and accommodated in a substantially radial direction by a jack (copy jack) or the like, and can be excavated further outside the excavation range by the cutter head 4.

  In this embodiment, the replenishment bit 25 is made to stand by on the inner peripheral portion of the cutter head 4 having the required number of bits necessary for excavation, and the cutter head 4 is worn with the wear of each bit. Only the replenishment bit 25 waiting at the inner peripheral portion of the cutter head 4 is configured to be movable to the outer peripheral portion with respect to the cutter head 4.

  At this time, it is preferable that the refilling bit 25 is stored in the normal cutter head 4. In other words, the shape and structure of the normal cutter head 4 itself is hardly changed by the refill bit 25. For example, the cutter head 4 is prevented from forming an overhanging portion for the refilling bit 25. Further, the shield body 3 and the center shaft 5 are not affected.

  In order to embody the above, a plurality of replenishing bits 25 are arranged in a band to form a replenishing bit string 26, and a movement groove 29 extending from the inner periphery to the outer periphery is formed in the cutter head 4, A plurality of replenishing bits 25 are configured to be movable along the movement groove 29 from the inner periphery to the outer periphery of the cutter head 4. In FIG. 1, the moving groove 29 has a length that does not reach the end on the outer peripheral side of the cutter head 4, but has a length that reaches the end on the outer peripheral side of the cutter head 4 as will be described later. You can also. Here, for example, a moving pedestal 30 described later is used to arrange the replenishing bits 25 into a replenishing bit string 26 in a band shape. The moving base 30 is slidably installed in the moving groove 29. The replenishment bit 25 and the moving base 30 are movable in the surface direction of the cutter head 4.

  In this embodiment, the supplementary bit 25 is the preceding bit 11. Then, the replenishment bit string 26 is directed substantially in the radial direction of the cutter head 4, and the moving groove 29 and the moving base 30 are extended substantially in the radial direction of the cutter head 4. The cutter head 4 is movable in the almost radial direction. In this way, the replenishment bit 25 can be accommodated in a minimum space. However, the arrangement direction and the moving direction of the belt-like supplementary bits 25 are not limited to this. Further, the arrangement and inclination angle of the replenishment bit 25 with respect to the moving base 30 are determined in accordance with the diameter size of the cutter head 4, the ground to be excavated, and the like.

  As shown in FIGS. 3 and 4, the refilling bit 25 before the movement can be made to wait on the surface of the cutter head 4 at the same level as the other bits (surface arrangement type). Further, the replenishment bit 25 before the movement can be waited at a lower level than other bits. When waiting at a low level, as shown in FIGS. 6 and 7, the replenishment bit 25 can be completely accommodated in the cutter head 4 (accommodation type), or the replenishment bit 25 can be A part of the cutter head 4 can be stored (for example, about half) (half storage type). In the case of being arranged at a low level, the inner peripheral portion of the moving groove 29 is formed deeper than the outer peripheral portion (submarine portion 29a), and the replenishing bit 25 before moving is made more than the other bits. It is possible to stand by in the state where it is retracted. At this time, the storage angle of the refilling bit 25 is determined in accordance with the diameter and thickness of the cutter head 4 and the ground to be excavated. Further, the insidious portion 29a on the inner peripheral side of the moving groove 29 may have a curved inclined shape as shown in FIGS. 3 and 4, but it may be a linear inclined shape, or an inclined shape and a linear shape. Can also be connected.

  As shown in FIGS. 12 and 13, the moving groove 29 is extended to the end on the outer peripheral side of the cutter head 4 (extended portion 29 b), and the end on the outer peripheral side of the replenishment bit string 26. It is also possible to provide outermost peripheral bits 32 such as trim bits so that the outermost peripheral bits 32 can appear on the outer peripheral portion of the cutter head 4 after the replenishment bit string 26 is moved. At this time, as shown in FIG. 13, the width dimension of the outermost peripheral bit 32 can be made larger than the width dimension of the moving groove 29 so as to protrude in the width direction. In this case, the surface arrangement type described above is used. Note that the width dimension of the outermost peripheral bit 32 can be made smaller than the width dimension of the moving groove 29 so as not to protrude in the width direction. In this case, a surface arrangement type, a storage type, or a semi-storage type can be selected.

  Here, the moving pedestal 30 for arranging a plurality of replenishing bits 25 in a belt shape to form a replenishing bit string 26 is of a pedestal plate type (moving pedestal 30a) as shown in FIGS. A sprocket type as shown in FIGS. 6 to 11 (moving base 30b) can also be used. The pedestal plate type moving pedestal 30a is suitable for the surface arrangement type because of its simple structure. Moreover, since the sprocket type moving base 30b can be deformed, it is suitable for a storage type or a semi-storage type.

  The pedestal plate type moving pedestal 30a and its moving groove 29 have a trapezoidal cross section in the width direction in FIG. 5, but the cross sectional shape is not limited to this. In this case, since the width dimension on the front surface side of the cutter head 4 is larger than the width dimension on the inner surface side, an unillustrated guide for preventing detachment is provided.

  As shown in FIGS. 8 and 10, the sprocket type moving pedestal 30 b is obtained by connecting a plurality of sprocket pieces 35 in the moving direction via a connecting portion. The connecting portion includes a connecting protrusion 36, a receiving recess 37, and a sandwiching tool 38. That is, a connecting projection piece 36 is formed at one end of each sprocket piece 35 excluding both ends of the movable base 30b (in this case, the end on the outer peripheral side of the cutter head 4), and the other end (in this case). In this case, a receiving recess 37 for accommodating the connecting protrusion 36 is formed on the inner periphery of the cutter head 4. A sandwiching tool 38 that sandwiches both side surfaces of the connecting projection 36 in the width direction is provided inside the receiving recess 37. On both side surfaces of the connecting protrusion 36, recessed portions 39 are formed which are sandwiched by the sandwiching tool 38. The sandwiching tool 38 includes a ball 38a that falls into the recess 39 and a spring 38b that biases the ball 38a in the protruding direction. Then, the sprocket piece 35 is rotated with this ball as a fulcrum, and is followed by the submerged portion 29a on the inner peripheral side of the moving groove 29. In order to prevent mutual interference when the sprocket pieces 35 are rotated, mutual interference taper portions 35 a are formed at both ends in the moving direction of the sprocket pieces 35 and at the inner surface side of the cutter head 4. Further, in FIG. 9, the sprocket type moving base 30b and its moving groove 29 are dovetailed with dovetail portions 35c and dovetail grooves 29c, respectively, on the inner surface side of the cutter head 4 in the cross section in the width direction. However, the cross-sectional shape is not limited to this.

  In addition, the movable pedestal 30 can be an integral type, a fitting type, a chain type, or the like.

  The moving pedestal 30 can be prevented from adhering to the moving groove 29, friction, and bidding by using a bearing such as a roll bearing 41 and a ball bearing 42 to perform support and lubrication. . In this embodiment, the roll bearing 41 is installed at the bottom of the movable pedestal 30 and the ball bearings 42 are installed at both sides of the movable pedestal 30.

  A moving means 44 is provided to move the moving base 30. The moving means 44 includes a drive mechanism using a hydraulic motor, a gear mechanism, a drive mechanism using a rack and pinion mechanism, a drive mechanism using traction using a chain or the like, a drive mechanism using a hydraulic jack 45 as shown in FIG. Can be used. The moving means 44 is provided inside the cutter head 4.

  The movable pedestal 30 can be fixed before and after movement. Examples of fixing means for the movable pedestal 30 include those for locking the drive by the hydraulic motor itself, gear mechanisms, those for locking the drive itself by the rack and pinion mechanism, those for locking the traction device itself such as a chain, hydraulic jack 45, etc. What locks a circuit, what locks using a lock pin after completion | finish of a movement of the movement base 30, etc. can be used. The lock pin can be a spring type, a hydraulic type, a mechanical type, a wedge type, or the like. This fixing means is provided inside the cutter head 4.

  The moving groove 29 can be provided with a blocking prevention means for preventing blocking due to excavation. As blockage prevention means, a high-pressure jet pipe is provided to clean the blockage portion with high-pressure water, a structure in which the back surface portion of the cutter head 4 is opened to prevent blockage, and the back surface of the cutter head 4 For example, the part may be opened and the gap of the closed part may be crushed and discharged to the open part.

  Next, the operation of this embodiment will be described.

  The shield machine 2 as the tunnel excavator 1 digs a natural ground by rotating a cutter head 4 attached to the tip of a cylindrical shield body 3 and becomes an inner wall of the excavation mine inside the shield body 3. By assembling the segments (lining bodies) and propelling the shield body 3 while supporting the reaction force on the segments, a tunnel or the like is constructed. The excavation of the natural ground enters the chamber 7 through the earth and sand intake port 22, and is discharged from the chamber 7 to the outside by a conveyor (not shown).

  When long-distance excavation or the like is performed, the surface bit wears out in the middle, so a process of replenishing the worn bit is performed. Bit replenishment is performed as follows. That is, the replenishment bit 25 waiting on the inner peripheral portion of the cutter head 4 is moved to the outer peripheral portion of the cutter head 4. More specifically, a plurality of replenishment bits 25 are arranged in a band to form a replenishment bit string 26, and the replenishment bit string 26 is moved along the movement groove 29 from the inner periphery to the outer periphery of the cutter head 4. Let A moving pedestal 30 is used for the arrangement and movement of the replenishment bit string 26, and the moving pedestal 30 is slid along the moving groove 29. For the movement of the movable pedestal 30, a moving means 44 provided inside the cutter head 4 is used. In addition, the movement base 30 is fixed by the fixing means before and after the movement. Further, when moving, the moving groove 29 is released from the closed state due to the excavation by the blocking preventing means.

  As described above, according to this embodiment, the refilling bit 25 is made to wait on the inner peripheral portion of the cutter head 4 having the required number of bits, and waits on the inner peripheral portion of the cutter head 4 as the bit wears. Since only the replenishing bit 25 that has been used can be moved to the outer peripheral portion with respect to the cutter head 4, the replenishing bit 25 is replenished to the outer peripheral portion of the cutter head 4 when the outer peripheral bit is worn. It becomes possible to do. Since the inner peripheral portion of the cutter head 4 has a short circumferential distance and the original bit and the replenishing bit 25 are doubled, the wear is less than that of the outer peripheral bit. Both the bit and the supplementary bit 25 are in a state of being preserved. Therefore, the excavation can be continued without any trouble even after the refilling bit 25 is moved to the outer peripheral portion.

  In addition, since only the refill bit 25 is moved from the inner peripheral portion to the outer peripheral portion with respect to the cutter head 4, the bit replenishment can be reliably performed with a simple configuration without adversely affecting the excavation mechanism. It becomes possible. In addition, since bit replenishment is possible at any time, it is possible to eliminate the need to specify the location and timing of bit replenishment. In addition, since ground improvement from the ground becomes unnecessary, it is freed from various limitations associated therewith, and the burden can be greatly reduced in terms of construction period and cost.

  At this time, a plurality of replenishing bits 25 are arranged in a band to form a replenishing bit string 26, and a moving groove 29 extending from the inner peripheral portion to the outer peripheral portion is formed in the cutter head 4, so that a plurality of replenishing bits are formed. 25 is configured to be movable from the inner peripheral portion to the outer peripheral portion of the cutter head 4 along the moving groove portion 29, thereby realizing a simple configuration and a mechanism for quickly replenishing bits with a minimum space. it can. Moreover, since the replenishment bit 25 can be placed on the cutter head 4 from start to finish, it is not necessary to attach / detach / store / recover the replenishment bit 25. An attachment / detachment mechanism, storage mechanism, and recovery mechanism are also unnecessary.

  In addition, the inner peripheral portion of the moving groove 29 is formed deeper than the outer peripheral portion, and the refilling bit 25 before moving is made to stand by in a state where it is retracted from other bits. This makes it difficult for the refill bit 25 to be exposed to the excavated gap during standby, so that wear of the refill bit 25 before movement can be minimized.

  Further, the moving groove 29 is extended to the end on the outer peripheral side of the cutter head 4 and the outermost peripheral bit 32 is provided at the end on the outer peripheral side of the replenishing bit string 26. Since the outermost peripheral bit 32 can appear on the outer peripheral portion of the cutter head 4, the outermost peripheral bit 32 can be replenished.

  By providing the bit replenishment mechanism having the above-described configuration, the tunnel excavator 1 such as the shield excavator 2 having the same effect as described above can be obtained.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the embodiments are only examples of the present invention, and the present invention is not limited to the configurations of the embodiments. Needless to say, design changes and the like within the scope of the present invention are included in the present invention.

It is a front view of the Example of this invention. FIG. 2 is an operation diagram of FIG. 1. It is sectional drawing which cut | disconnected FIG. 1 in radial direction. FIG. 3 is a cross-sectional view of FIG. 2 cut in the radial direction. It is sectional drawing of the width direction of the movement base part of the base plate type | mold type of FIG. It is sectional drawing similar to FIG. 3 at the time of making a movement base into a storage type. It is sectional drawing similar to FIG. 4 at the time of making a movement base into a storage type. FIG. 8 is an enlarged side view of the sprocket type moving base of FIG. 7. It is sectional drawing of the width direction of the movement base part of the sprocket type of FIG. It is the disassembled perspective view to which the sprocket piece of FIG. 8 was expanded. It is a front view of the sprocket piece of FIG. It is sectional drawing which cut | disconnected radial direction FIG. 1 in the case of having a movement base provided with the outermost periphery bit. FIG. 13 is a partial perspective view of FIG. 12.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tunnel excavator 4 Cutter head 25 Refilling bit 26 Refilling bit string 29 Moving groove part 30 Moving base 32 Outermost peripheral bit

Claims (5)

Wait for the replenishment bit on the inner periphery of the cutter head having the required number of bits,
A bit replenishing mechanism and a tunnel excavator characterized in that only the replenishment bit waiting on the inner peripheral portion of the cutter head can be moved to the outer peripheral portion with respect to the cutter head in accordance with wear of the bit.   A plurality of replenishing bits are arranged in a band to form a replenishing bit string, and a moving groove extending from the inner peripheral part to the outer peripheral part is formed in the cutter head, and the replenishing bit string is cut along the moving groove part. 2. A bit replenishing mechanism and a tunnel excavator according to claim 1, wherein the bit replenishment mechanism and the tunnel excavator are configured to be movable from an inner periphery to an outer periphery of the head.   The inner groove side portion of the moving groove is formed deeper than the outer peripheral side portion so that the refilling bit before the movement can stand by in a state where it is pulled in more than the other bits. Item 3. A bit replenishment mechanism and a tunnel excavator according to Item 2.   The moving groove is extended to the end on the outer peripheral side of the cutter head, and the outermost peripheral bit is provided at the end on the outer peripheral side of the replenishing bit string. 4. A bit replenishing mechanism and a tunnel excavator according to claim 2, wherein an outer peripheral bit can appear.   A tunnel excavator comprising the bit replenishment mechanism according to any one of claims 1 to 4.

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