JP2003172093A - Shield machine, bit exchange method and excavation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply, safely and efficiently provide a shield machine and its bit exchange method in underground. <P>SOLUTION: A circling movable chain 15a is provided by directing the front side and rear face side of a cutter head 2 in the substantially radial direction on the shield machine 1 provided with the rotating cutter head 2 contacted on a heading, and bits 14, 14... are provided in the form of a row on the chain 15a along a circumferential direction. In addition, a lock chamber 33 capable of exchanging rear face side bits 12, 12... of the cutter head 2 is provided by entering the inside of an excavation chamber 36 provided rearward of the cutter head 2 to be adhered to the rear face of the cutter head 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield excavator used in a shield construction method, a bit exchanging method, and an excavating method.

[0002]

2. Description of the Related Art The shield method, which is one of the methods for constructing underground structures and tunnels, is a cylindrical shell, that is, a shield is pushed into the ground while the front surface is excavated in the ground, and the ground immediately after excavation is performed. The method is to protect and immediately construct a tunnel while constructing a lining at the rear. The lining is performed by, for example, assembling a reinforced concrete block called a segment into an annular shape. The inner wall of the tunnel is formed by continuously assembling the segments in the longitudinal direction. The shield method is characterized by safe and reliable work, and when it is difficult to use the open-cut method of building a structure by digging the ground directly from above, such as in a city center with dense buildings, The shield method is used. The shield excavator used in the shield construction method is an excavator that efficiently cuts and takes in natural ground by pushing a head with a large number of bits on the front side while rotating it using a drive mechanism such as a hydraulic motor. Is.

In recent years, the shield work has been made longer in terms of construction environment, economy, and shortening of construction period, and along with this, it is necessary to improve the durability of each part of the shield excavator. Furthermore, it is considered that it will be necessary to excavate various soil types due to the long distance, and selecting and exchanging a bit suitable for each soil type will greatly affect the construction efficiency.

[0004]

Among the various parts of the shield excavator, the one that is particularly deteriorated is the bit that excavates in direct contact with the natural ground. To improve the construction efficiency, the bit is replaced during construction. Had to do. Therefore, conventionally, a worker enters the space between the face of the face and the shield excavator to replace the bit by making the ground around the face of the face self-supporting by ground improvement, or at the destination of the progress of the shield excavator. A pit (intermediate vertical shaft) of a size that could be exchanged was excavated from the surface of the ground, and bits were exchanged in the intermediate vertical shaft after excavating until reaching the intermediate vertical shaft. But in recent years
In the shield construction method in urban areas, it is becoming difficult to construct an intermediate shaft because it is difficult to acquire land due to the crowding of surface structures. Further, in order to effectively use the underground space, it is necessary to construct the shield work with a deeper and larger cross section, but in such a case it was difficult to construct the intermediate shaft. In addition, the soil quality may change significantly during the construction as the shield work becomes longer. In such a case, in order to carry out the construction efficiently, it was necessary to replace the bit with one suitable for each soil type during construction. Under these construction conditions, replacing the bit by using the above-mentioned conventional method requires a lot of cost and a long construction period.

In addition to the above-mentioned conventional method, for example, Japanese Patent Laid-Open No. 11-350877 discloses a method of exchanging bits by rotating a cutter spoke around an axis. However, according to this bit exchanging method, the bit provided near the outer circumference of the cutter head, which is heavily worn, and the bit provided near the center, which is less worn, are also replaced at the same time, which is not economical. was there.

An object of the present invention is to provide a shield excavator which is simple, safe and efficient in the ground, and a bit exchanging method therefor.

[0007]

In order to solve the above problems, the invention according to claim 1 is a shield excavator (1) having a cutter head (2) having a bit and rotating. In the cutter head, the front side of the cutter head is moved substantially in the radial direction to wrap around to the back side of the cutter head, and the back side is moved in the reverse direction to the front side in the opposite direction to the front side. An annular member (chain 15a) provided so as to be able to circulate so as to wrap around, and the annular member,
Bits (12, 14) provided in a row along the circumferential direction of the annular member so as to extend over substantially the entire circumference of the annular member;
An annular member drive means (driving source) for driving the annular member to move in a circular manner, and by rotating the annular member, a bit located on the front side of the cutter head and a bit located on the back side of the cutter head. It is characterized in that it can be freely exchanged with the bit.

According to the first aspect of the invention, when the bit wears during excavation, the worn bit located on the front side of the cutter head and the back surface of the cutter head are rotated by rotating the annular member. The bit located on the side can be easily exchanged. Since the bit can be moved along the radial direction of the cutter head by the circular movement of the annular member, the movement distance due to the rotation of the cutter head is long and the bit on the outer peripheral side of the cutter head, which is easily worn, has the movement distance due to the rotation of the cutter head. It is possible to move the bit on the center side of the cutter head that is short and less likely to wear, and conversely, move the bit on the center side of the cutter head to the outer peripheral side of the cutter head. As a result, it is possible to prevent the bit on the outer peripheral side of the cutter head from being greatly worn. When the bits are arranged in a row along the radial direction on the cutter head, the bit density (the number of bits per unit area) on the outer peripheral side of the cutter head becomes lower than that on the center side of the cutter head, The face portion corresponding to the central portion is more likely to be excavated, and the bit on the outer peripheral side of the cutter head is more easily worn as described above.For example, on the front side of the cutter head, insert the bit into the cutter head. Of the cutter head from the center side of the cutter head to the outer side of the cutter head by moving the annular member from the outer side to the center side of the cutter head. If the bits are replaced one by one, the bits on the outer peripheral side of the cutter head will be replaced relatively frequently, and the outer peripheral side of the cutter head will be replaced. Min drilling capacity can be prevented. The method of exchanging the bit by the circular movement of the annular member is not particularly limited, and the bit may be exchanged by rotating the annular member from the outer peripheral side to the central side on the front side of the cutter head, The bit may be replaced by rotating the annular member in the opposite direction. Further, the front side bit and the rear side bit of the cutter head may all be exchanged by one exchange, or the front side bit and the rear side bit may be exchanged sequentially in plural exchanges. May be.

The annular member may be, for example, a narrow chain-shaped member or a wide steel belt. A chain-shaped member or a steel belt, which is an annular member, is an annular member in which a large number of steel members are rotatably connected to each other, like a so-called chain or infinite start, and its width is arbitrary. If the width of the steel member along the direction orthogonal to the radial direction of the entire annular member is narrow, it becomes a chain shape, and if it is wide, it becomes a belt shape. The annular member needs to have strength enough to withstand excavation, and a member having a structure in which a hard member such as a metal is connected is more preferable than a flexible member such as a rubber.
In addition, as long as it is reinforced by some method and has a sufficient strength, a flexible member such as rubber formed in an annular shape may be used. Further, one annular member may be provided with the bits in a line along the substantially radial direction of the cutter head in a state of being attached to the cutter head along the radial direction thereof, or along the substantially radial direction of the cutter head. Bits may be provided in a plurality of columns. Further, it is preferable that the cutter head is provided with a plurality of annular members, and in this case, it is preferable that the annular members are arranged at equal angular intervals along the circumferential direction.

Further, the annular member may be provided from the vicinity of the center of the cutter head to the outer peripheral edge of the cutter head or the vicinity of the outer peripheral edge thereof. The bit may be fixedly arranged, and the guide member may be arranged along the radial direction on the outer peripheral portion of the cutter head (for example, on the outer peripheral side of 1/2 of the radius of the cutter head). Further, as will be described later, the annular member may be rotated during excavation, that is, during rotation of the cutter head. In this case, the bit may move back and forth multiple times on the front side and the back side of the cutter head. It is also possible to provide a detection means for detecting the wear state of the bit and replace the bit when the bit is worn.

According to a second aspect of the present invention, in the shield excavator according to the first aspect, the cutter head has a plurality of spoke portions (17) extending in a radial direction from a center side of the cutter head toward an outer peripheral side thereof. ) Is provided, and the annular member is rotatably supported by the spokes.

According to the second aspect of the present invention, by rotating the annular member, the bit supported by the spoke portion can be easily replaced.

According to a third aspect of the present invention, in the shield excavator according to the first or second aspect, the annular member is arranged on an outer peripheral portion of the cutter head.

According to the third aspect of the present invention, the bit on the outer peripheral side has a larger amount of wear as compared with the center side of the cutter head as described above, so that the bit on the outer peripheral side can be replaced. As a result, it is possible to effectively extend the digging distance. Note that, for example, in a large-diameter shield excavator, a plurality of annular members are provided at equal angles along the radial direction from the central portion of the cutter head to the outer peripheral edge portion, and the outer periphery of the cutter head between these annular members is provided. A short annular member may be provided in the portion. Here, the outer peripheral portion is, for example, from the half of the radius of the cutter head to the outer side, but is not particularly limited to this, and a bit fixed to the center side of the cutter head is provided and an annular member is provided on the outer peripheral side. In the case of providing, the side where the fixed bit is provided may be the central portion and the side where the annular member is provided may be the outer peripheral portion.

According to a fourth aspect of the present invention, in the shield excavator according to any one of the first to third aspects, the annular member is rotated during excavation by rotating the cutter head. Thus, the moving distance of each bit provided on the annular member during excavation is substantially equalized.

According to the fourth aspect of the present invention, since the moving distance of each bit is uniform, it is possible to prevent the bit on the outer peripheral side of the cutter head from being rapidly worn as in the conventional case. Accordingly, when the bit density is the same as the conventional one, the number of usable bits is increased by the number of bits arranged on the back surface of the cutter head, and it becomes possible to excavate a long distance as compared with the conventional one. By rotating the annular member while excavating, a large load is applied to the annular member driving means and the cutter head is rotating, as compared with the case where the annular member is rotated while the cutter head is not rotating. While the annular member continues to rotate for a long time, the annular member will rotate for a long time as compared with the case of simply exchanging the bit, which requires a larger amount of energy. Some will be used for excavation by moving the bit in contact with the face in the radial direction.

According to a fifth aspect of the present invention, in the shield excavator according to any one of the first to fourth aspects, the bit provided on the annular member is exchangeably provided on the annular member, and the cutter is provided. The bit located on the back side of the head is replaceable from inside the shield excavator body.

According to the invention described in claim 5, in the above-mentioned structure, basically, all the bits on the front side of the cutter head of the annular member and the bits on the back side of the same number as the bits are all provided. Once replaced, the bit cannot be exchanged anymore, and it is basically difficult to extend the excavation distance beyond the distance that can be excavated by one bit exchange, but the bit of the annular member is removed, By exchanging them, it is possible to further extend the digging distance. If the annular member is rotated during excavation as described above, wear of each bit is suppressed while the bit is on the back side, so that the service life of the bit increases and wears evenly. However, also in this case, it is difficult to extend the excavation distance longer than the distance that excavation can be performed by one bit exchange. However, the excavable distance can be extended by removing and replacing the bit of the annular member as described above.

According to a sixth aspect of the present invention, in the shield excavator according to the fifth aspect, a chamber (excavation chamber 36) is provided at the rear of the cutter head, and the chamber enters into the chamber and the rear surface of the cutter head is provided. Lock chamber (33) that keeps the inside sealed by closely contacting
And the bit on the back side of the cutter head is replaceable from the lock chamber.

According to the sixth aspect of the present invention, even in a shield excavator of a type in which earth and sand, muddy water, etc. are kept under pressure in the chamber to retain the face of the face, the lock chamber is kept inside the chamber. The space for performing the bit exchanging work can be secured in the chamber by advancing into the chamber.

A seventh aspect of the present invention is a bit exchanging method for a shield excavator according to any one of the first to sixth aspects, wherein the bit is moved by rotating the annular member. By moving along the radial direction of the cutter head, a bit on the back side of the cutter head,
It is characterized in that the bit on the front side of the cutter head is replaced.

According to the invention of claim 7, claim 1
It is possible to obtain the same effect as that of any one of to 6 above.

The invention according to claim 8 is the excavating method in the shield excavator according to any one of claims 1 to 6, wherein the cutter head is rotated and the annular member is provided. It is characterized in that the excavation is performed while the orbit is being moved.

According to the eighth aspect of the present invention, since the moving distance of each bit is equal, the wear is also equal. Therefore, it is possible to prevent the bit on the outer peripheral side of the cutter head from being rapidly worn as in the conventional case.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.
A detailed description will be given based on FIG. FIG. 1 (A) is a schematic front view of the shield excavator 1, and FIG. 1 (B) is a schematic side view. The shield excavator 1 has a body 4 including a substantially circular cutter head 2 that abuts on a face and a excavation chamber 36 that is connected to the face of the cutter head 2 opposite to the face of the face and that takes in the excavated earth and sand. have. A substantially circular bulkhead 34 that separates the body 4 and the cutter head 2 is located behind the cutter head 2. Between the cutter head 2 and the bulk head 34, earth and sand excavated by a bit collects. A drilling chamber 36 is formed. A mud pressure (or earth pressure, mud pressure) necessary to prevent the collapse of the face is applied to the excavation chamber 36. As shown in FIG. 1 (B), a screw conveyor 32 is disposed in a tilted manner in the body 4, and the front end of the screw conveyor 32 penetrates the bulkhead 34 and reaches the excavation chamber 36. ing.
The earth and sand accumulated in the excavation chamber 36 passes through the screw conveyor 32 and is carried out to the rear of the body 4. An opening 35a having a predetermined size is formed in the center of the upper portion of the bulkhead 34,
An opening / closing door 35 that can be opened and closed is formed in the opening 35a (see FIG. 1A). A lock chamber 33 used when exchanging the bit is provided at a position corresponding to the opening / closing door 35 in the body 4. As shown in FIG. 2, the lock chamber 33 has a box shape having an opening on the opening / closing door 35 side (left side in FIG. 2), and a waterproof rubber 33a is attached so as to surround the edge of the opening. Note that FIG. 2 shows a state in which the lock chamber 33 penetrates through the opening / closing door 35 that opens, enters the excavation chamber 36, and moves to reach the spoke portion 17 described later.

At the center of the cutter head 2, a drive shaft 3 rotatably driven by a hydraulic motor or the like (not shown) is rotatably attached. The cutting head is excavated by rotating the cutter head 2 with the rotation of the drive shaft 3.
Fixed bits 20, 20, ... Are provided on the outer peripheral portion of the cutter head 2.
Are attached at a predetermined interval in the circumferential direction. On the surface of the cutter head 2 facing the face, four slits 2a, 2a ... Are formed along the radial direction at intervals of 90 degrees along the circumferential direction of the cutter head 2. The slits 2a, 2a ... Are provided with long spokes 17, 17. Chain parts 15, 15 ... Having a plurality of bits 14, 14 ... Are provided on both sides of each of the spoke parts 17, 17, ... Along the axial direction of the spoke parts 17, 17.

Although one chain portion 15 will be described in detail below, actually, eight chain portions 15 are provided on the cutter head 2 and they have the same structure.
The chain portion 15 is composed of an annular chain 15a (annular member) having the bits 14, 14 ... Attached to its surface, sprockets 30 and 31 for rotationally driving the chain 15a, and the like. Here, for convenience, the above-mentioned bits 14 and 1
Of 4 ..., those located on the back side of the cutter head 2 are denoted by different reference numerals and designated as bits 12, 12. Both the bit 12 and the bit 14 are bits similarly attached to the chain 15a, and since the chain 15a is rotatable, the positions of the bit 12 and the bit 14 are interchangeable. Bits 14, 14, ... (12, 12,
Are attached to the steel members that are detachably connected to each other and that constitute the chain 15a by fastening means such as bolts or other joining members.

The sprockets 30 and 31 are connected to a drive source (annular member drive means) not shown and rotate in conjunction with each other. The chain 15a stretched around the sprockets 30 and 31 rotates as the sprockets 30 and 31 rotate. The sprockets 30 and 31 can be rotated to the left or right.

Next, a bit exchanging method in the shield excavator 1 will be described. The shield excavator 1 excavates the ground by a method similar to that of the conventional shield excavator. First, fixed bits 20, 20, ..., Bit 1
Excavation is performed by 4, 14 ... When excavation is performed to some extent, the excavation efficiency of the shield excavator 1 is reduced due to wear of the fixed bits 20, 20 ..., Bits 14, 14 ... And changes in soil quality. Then, the chain 15a is rotated by driving the sprockets 30 and 31, and the cutter head 2
The unused bits 12, 12 ... Located on the back surface of the cutter head 2 are moved to the front surface (cutting face side) of the cutter head 2. On this occasion,
It is not necessary to replace all the bits 14, 14 ... With the bits 12, 12, ..., For example, only the bits 14, 14 ... Near the outer periphery of the cutter head 2 which is severely damaged are replaced, for example, 1/4 or 1 / from the outer periphery. The chain 15a may be rotated and stopped so that the two bits 14, 14 ...

Bit 1 attached to chain 15a
When 2, 12, ..., 14, 14, ... Are all worn, a new bit is replaced by the following procedure. First, the opening / closing door 35 provided on the bulkhead 34 is opened to advance the lock chamber 33 in the body 4. Next, the door 3
The water stop rubber 33a attached to the edge of the lock chamber 33 that has passed 5 is pressed against the spoke portions 17 of the chain portion 15 including the chain 15a to stop the water. Further, the inside of the lock chamber 33 is pressurized to reliably stop the water. A worker enters the stopped lock chamber 33,
The worn bits 12, 12, ..., 14, 14 ... are removed, and a new bit is attached to the chain 15a. Further, the chain 15a may be configured so that it can be divided at a predetermined position. In this case, the bits 12, 1 in the lock chamber 33
2 ... can be replaced together with a part of the chain 15a.

By the way, as described above, bits 14, 14
When exchanging the ..., Not only the chain 15a may be rotated, but the excavation may be performed while the chain 15a is rotated. In this case, in order to efficiently excavate, the chain 15
It is necessary to control the rotation of a. Below, the chain 15a
The loci of the bits 14, 14, ... FIG. 3 shows the loci of the bits 14, 14 ... When the cutter head 2 is rotated without rotating the chain 15a. This is the locus of the bits 14, 14 ... Attached to one chain 15a. In addition, in FIG. 3 showing the locus of the bit and FIGS. 4 and 5 described later, the bit 1 for each constant rotation angle of the cutter head 2 is shown.
The position of 4 is indicated by a circle, a square, a triangle, etc., and a straight line (a solid line, a one-dot chain line, a two-dot chain line, a broken line, etc.) is connected between the positions to simply illustrate the locus of the bit 14, but the actual bit 14 The locus of is a circular arc or a curve close to it. As shown in FIG. 3, the locus of the bit 14 on the outer peripheral side of the cutter head 2 is longer than the locus of the bit 14 on the inner peripheral side of the cutter head 2. 4 shows that when the cutter head 2 is rotated counterclockwise, at the same time the chain 15a provided with the bits 14, 14 ... Is rotated from the outer periphery toward the center at 1 Hz on the front surface of the cutter head 2. …
Is the locus (only the loci of the bits 14, 14, ... Provided in one chain 15a are shown). Rotating at 1 Hz means that the chain 15a also makes one revolution while the cutter head 2 makes one revolution. Note that FIG. 4 shows a locus of 14 bits provided on one chain when they appear on the front surface of the cutter head 2.
Further, FIG. 4 shows the position of the bit 14 for each predetermined angle of the cutter head 2 as described above, and shows the trajectory of the bit 14 simply by connecting the positions of the bit 14 with a straight line.

Then, as shown in FIG. 4, each bit 14,
The locus of 14 ... Draws a curved locus deviated from the circular locus of the bit shown in FIG. 3 to the center of the cutter head 2, and the bit 14 located on the outer peripheral portion of the cutter head 2 is As it rotates, it moves toward the center of the cutter head 2, and when it reaches the vicinity of the central portion of the cutter head 2, it turns to the back side of the cutter head 2. As a result, the locus of the bit 14 on the outer peripheral side of the cutter head 2 is
It does not become longer than the locus of the bit 14 on the inner peripheral side, and the length of the locus of each bit 14 supported by the chain 15a becomes uniform, and only the bit 14 on the outer peripheral side of the cutter head 2 wears first. It will not happen. Therefore, it is possible to efficiently excavate with each bit 14,
Accordingly, the excavation distance of each bit 14 as a whole can be extended.

FIG. 5 shows two different spoke parts 17 and 1.
While excavating while rotating each chain 15a of No. 7 at 0.5 Hz (the chain 15a rotates half a turn when the cutter head 1 makes one rotation), the loci of the bits 14, 14 ... Provided on each chain 15a. The loci of the bits 14, 14 ... When the rotations of the chains 15a are controlled so as not to overlap each other are shown. In addition, No.
1-No. Bits 14 and 14 whose locus up to 7 are provided on one of the two chains 15a
... shows the locus of ... 8 to No. Up to 14 show the loci of the bits 14, 14 ... Provided on the other chain 15a. In this way, when controlling the rotation of the chains 15a, 15a ... Provided on the cutter head 2, the bits 14, 1 provided on the chains 15a, 15a.
4 ... Chains 15a and 15 so that the loci of 4 do not overlap.
By synchronizing and controlling with a ..., different chains 1
It is possible to efficiently excavate the ground without excavating the bits 14 of the 5a, 15a, ...

According to the shield excavator 1 and the bit exchanging method thereof in the present invention described above, the spoke portions 17, 1 are provided.
.. are provided with rotatable chain portions 15, 15 ... With bits 14, 14. When the bits 14 facing the face wear, the chain 15a
By rotating the cutter head 2, the unused bits 14, 14 ... Located on the back side of the cutter head 2 are removed.
To the front side of. That is, it is not necessary to improve the ground around the intermediate shaft and the face, and the chains 15a, 15
.. are rotated to move the bits 14, 14 ... Positioned on the back surface of the cutter head 2 to the front surface, so that the bits can be easily replaced, resulting in a significant cost reduction. Further, since the bit 14 can be replaced promptly, the work period can be shortened. Further, since it is possible to replace only the bits 14, 14 ... Of the outer peripheral portion, which is heavily worn, there is no waste. Further, the chains 15a, 15a ... May be excavated while rotating. In that case, the bits 14, 14, ...
It is not necessary to replace the bits 14 near the outer circumference.

The present invention is not limited to the above embodiment. For example, it is possible to provide the shield excavator 1 in the above-described embodiment with a wear detecting device and control the rotation of the chain 15a according to the detected wear degree. Further, in the above embodiment, the spoke portion 17
, All of which are attached to the chain 15a, but near the outer peripheral portion of the cutter head 2,
Only the worn bits 14, 14 ... Chain 15a
May be attached to. That is, a fixed cutter bit is provided on the inner peripheral side of the cutter head 2, and the chain portion 1 is provided at a portion corresponding to, for example, 1/2 length from the outer periphery of the cutter head.
5 may be provided. Further, the chain portion 15 may be longer or shorter than half the length from the outer circumference of the cutter head 2.

[0036]

According to the first aspect of the invention, when the bit wears during excavation, the worn bit located on the front side of the cutter head is rotated by rotating the annular member, and the cutter head. The bit located on the back side of can be easily replaced. Since the bit can be moved along the radial direction of the cutter head by the circular movement of the annular member, the movement distance due to the rotation of the cutter head is long and the bit on the outer peripheral side of the cutter head, which is easily worn, has the movement distance due to the rotation of the cutter head. It is possible to move the bit on the center side of the cutter head that is short and less likely to wear, and conversely, move the bit on the center side of the cutter head to the outer peripheral side of the cutter head. As a result, it is possible to prevent the bit on the outer peripheral side of the cutter head from being greatly worn.

Further, when the bits are arranged in a row along the radial direction on the cutter head, the bit density (the number of bits per unit area) on the outer peripheral side of the cutter head becomes lower than that on the central side of the cutter head. The face portion corresponding to the central portion of the cutter head is in a state of being easily excavated, and the bit on the outer peripheral side of the cutter head is more easily worn as described above. Is moved from the outer peripheral side of the cutter head to the center side, and on the back side of the cutter head, the annular member is moved around so that the bit is moved from the center side of the cutter head to the outer peripheral side. Alternatively, if you replace the bits a few at a time, the bits on the outer peripheral side of the cutter head will be replaced relatively often, and Drilling capability of the outer peripheral portion of the soil can be prevented.

According to the second aspect of the invention, by rotating the annular member, the bit supported by the spoke portion can be easily replaced.

According to the third aspect of the present invention, the bit on the outer peripheral side has a greater amount of wear as compared with the center side of the cutter head as described above, so that the bit on the outer peripheral side can be replaced. As a result, it is possible to effectively extend the digging distance.

According to the fourth aspect of the present invention, since the moving distance of each bit is equalized, it is possible to prevent the bit on the outer peripheral side of the cutter head from being rapidly worn as in the conventional case. Accordingly, when the bit density is the same as the conventional one, the number of usable bits is increased by the number of bits arranged on the back surface of the cutter head, and it becomes possible to excavate a long distance as compared with the conventional one. According to the invention described in claim 5, in the above structure, basically, all the bits on the front side of the cutter head of the annular member and the bits on the back side of the same number as the bits are exchanged. For example, it is impossible to change the bit any more, and it is basically difficult to extend the excavation distance beyond the distance that can be excavated by one bit exchange, but it is necessary to remove and replace the bit of the annular member. With this, it is possible to further extend the distance that can be dug. If the annular member is rotated during excavation as described above, wear of each bit is suppressed while the bit is on the back side, so that the service life of the bit increases and wears evenly. However, even in this case, it is difficult to extend the excavation distance longer than the distance that can be excavated by one bit exchange, but as described above, it is possible to extend the excavation distance by removing and exchanging the bit of the annular member. You can

According to the sixth aspect of the present invention, even in a shield excavator of a type in which earth and sand, muddy water, etc. are kept under pressure in the chamber to earthen the face, the lock chamber is kept inside the chamber. The space for performing the bit exchanging work can be secured in the chamber by advancing into the chamber.

According to the invention of claim 7, claim 1
It is possible to obtain the same effect as that of any one of to 6 above.

According to the invention described in claim 8, since the moving distance of each bit is uniform, the wear is also uniform. Therefore, it is possible to prevent the bit on the outer peripheral side of the cutter head from being rapidly worn as in the conventional case.

[Brief description of drawings]

FIG. 1A is a schematic front view of a shield excavator that is an embodiment of the present invention, and FIG. 1B is a schematic side view.

FIG. 2 is a cross-sectional view of the lock chamber when the lock chamber of the shield excavator according to the embodiment of the present invention is pressed against the chain portion.

FIG. 3 is a locus of bits when the cutter head is rotated once without rotating the chain portion.

FIG. 4 is a locus of bits when the chain head is rotated once toward the center at 1 Hz and the cutter head is rotated leftward.

FIG. 5 is a locus of bits when the positions of bits are shifted and controlled in two chain parts.

[Explanation of symbols]

1 shield excavator meis 2 cutter head 12, 14 bits 15 Chain part 15a Chain (annular member) 17 Spokes 20 fixed bits 33 lock room 33a waterproof rubber 34 Bulkhead 35 open / close door

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshio Oguri             Nishimatsuken 1-20-10 Toranomon, Minato-ku, Tokyo             Inside the corporation (72) Inventor Takeshi Taguchi             Nishimatsuken 1-20-10 Toranomon, Minato-ku, Tokyo             Inside the corporation (72) Inventor Shigeaki Saito             Nishimatsuken 1-20-10 Toranomon, Minato-ku, Tokyo             Inside the corporation (72) Inventor Toru Watanabe             Nishimatsuken 1-20-10 Toranomon, Minato-ku, Tokyo             Inside the corporation F term (reference) 2D054 AC02 BA07 BB06 BB07

Claims (8)

[Claims] 1. A shield excavator equipped with a cutter head having a bit and rotating, wherein the cutter head is moved to the rear side of the cutter head by moving the front side of the cutter head substantially along a radial direction. An annular member provided so as to wrap around and move around the rear side in the direction opposite to the front side substantially in the radial direction so as to wrap around to the front side, and the annular member along the circumferential direction of the annular member. In a row and provided with a bit provided so as to extend over substantially the entire circumference of the annular member, and an annular member drive means for driving the annular member to move around, by rotating the annular member, A shield excavator characterized in that a bit located on the front side of the cutter head and a bit located on the back side of the cutter head are exchangeable. 2. The cutter head is provided with a plurality of spokes extending in a radial direction from a center side of the cutter head toward an outer peripheral side, and the annular member is rotatably supported by the spokes. The shield excavator according to claim 1, wherein the shield excavator is provided. 3. The annular member is arranged on an outer peripheral portion of the cutter head.
The listed shield excavator. 4. The excavation is performed by rotating the cutter head, and the annular member is rotated to make the moving distances of the bits provided on the annular member during excavation substantially equal. The shield excavator according to any one of claims 1 to 3. 5. The bit provided on the annular member is exchangeably provided on the annular member, and the bit located on the back side of the cutter head is exchangeable from the inside of the shield excavator body. The shield excavator according to any one of claims 1 to 4. 6. A chamber is provided at the rear of the cutter head, and a lock chamber is provided to keep the inside of the chamber closed by advancing into the chamber and adhering to the back surface of the cutter head. The shield excavator according to claim 5, wherein the bit on the back side of the cutter head is replaceable. 7. The bit exchanging method in a shield excavator according to claim 1, wherein the bit is moved in a radial direction of the cutter head by rotating the annular member. By moving the bit on the back side of the cutter head to replace the bit on the front side of the cutter head. 8. A method of excavating in a shield excavator according to any one of claims 1 to 6, wherein the cutter head is rotated and the annular member is rotated. And a method for excavating, which comprises excavating.