Mining or in situ disintegration of hard material – Hard material disintegrating machines – Rotary cutter head with advance direction coincident or...
Reexamination Certificate
2000-07-13
2002-02-19
Tsay, Frank S. (Department: 3672)
Mining or in situ disintegration of hard material
Hard material disintegrating machines
Rotary cutter head with advance direction coincident or...
C299S059000, C405S138000
Reexamination Certificate
active
06347838
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for replacing cutters, such as roller cutters and cutter bits, of a tunnel-excavating machine; a method for excavating a tunnel; and a tunnel-excavating machine, such as a tunnel-boring machine or a shield machine.
2. Description of Related Art
A tunnel-boring machine for excavating a tunnel in rock strata, which is one example of the tunnel-excavating machine, includes a cylindrical machine body; a cutterhead attached rotatably to a front portion of the machine body; a number of disc cutters and cutter bits attached to the cutterhead; a gripper located behind the machine body and adapted to grip an existing tunnel wall under pressure; and a plurality of thrust jacks extending between the machine body and the gripper. While the gripper bears a reaction force arising from excavation, the thrust jacks are extended while the cutterhead is rotating, to thereby advance the machine body. As a result, the disc cutters and the cutter bits fracture a rock formation located ahead, thereby excavating a tunnel.
A recent tendency toward an increase in the length of a tunnel to be excavated involves wear of disc cutters and cutter bits attached to the cutterhead in the midst of excavation of the tunnel. Since worn disc cutters and cutter bits cause an impairment in excavation efficiency, excavation operations must be halted in order to replace the worn disc cutters and cutter bits. Conventionally, when disc cutters and cutter bits are to be replaced, ground located ahead is stabilized through injection of chemical liquid or through freezing. When excavation progresses to the ground-stabilized point, the tunnel-boring machine retreats, and muck is removed from inside a chamber of the machine. Then, workers enter a space located ahead of the cutterhead and the chamber in order to replace the disc cutters and cutter bits.
However, this replacement operation involves the cost of chemical liquid used to stabilize ground and is thus uneconomical. Furthermore, the replacement operation consumes a relatively long period of time, thereby impairing work performance. Since workers work within a narrow work space, such as a space located ahead of the cutterhead and a space within the chamber, restrictive work conditions increase a burden on workers. To cope with this problem, a tunnel-excavating machine enabling replacement of cutter bits within an machine body is disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) No. 280878/1998.
The tunnel-excavating machine disclosed in Japanese Patent Application Laid-Open (Kokai) No. 280878/1998 is configured in the following manner. A cutterhead is rotatably attached to a front portion of a skin plate. A guide rail is disposed on the cutterhead such that an end portion of the guide rail located toward the center of the cutterhead is bent toward the interior of the machine. A plurality of holders which are connected to one another in a bendable manner are movably supported by the guide rail. The holders carry the corresponding cutter bits. A cutter bit replacement chamber is attached to the end portion of the guide rail via a gate mechanism. Each of the cutter bits can be moved into the cutter bit replacement chamber by means of a moving jack so as to replace the cutter bit with new one therein.
Generally, a plurality of cutter spokes are radially disposed on the front face of a cutterhead. A number of cutter bits are attached to each of the cutter spokes. In the tunnel-excavating machine disclosed in the above-mentioned publication, the guide rails are mounted on the corresponding cutter spokes, and the cutter bits are movably attached to the guide rails. When the cutter bits are to be replaced, each is moved into the cutter bit replacement chamber attached to an end portion of the corresponding guide rail and is then replaced with a new cutter bit therein. Since each of the cutter spokes (guide rails) must be equipped with the cutter bit replacement chamber and the moving jack, the machine structure becomes complex. Also, since the cutter bit replacement chambers are located proximity to each other, workers suffer inconvenience in replacing cutter bits. It is conceivable that the cutter bit chamber and the moving jack may be attached only to the guide rail which carries cutter bits to be replaced. However, this involves attachment and detachment of the cutter bit replacement chamber and the moving jack to and from each of the guide rails, resulting in low work efficiency.
Meanwhile, a tunnel-excavating machine advances while a cutterhead is rotated, thereby fracturing by means of cutter bits a stratum located ahead and thus excavating a tunnel. Thus, muck is present between the cutterhead and an excavation face. In the case of the tunnel-excavating machine disclosed in the above-mentioned publication, worn cutter bits are moved along the guide rail mounted on the corresponding cutter spoke and into the cutter bit replacement chamber attached to an end portion of the guide rail, and are then replaced with new cutter bits therein. Muck which accompanies excavation enters the guide rail and hinders movement of cutter bits along the same at the time of cutter bit replacement.
When worn cutter bits located on the front face of the cutterhead are moved into the cutter bit replacement chamber along the guide rail for replacement with new cutter bits, an empty space is formed in the guide rail. Since muck enters the empty space, when new cutter bits are to be returned along the guide rail to a predetermined position on the cutterhead, the filling muck hinders the return of the new cutter bits.
Also, since an opening is formed in the cutterhead in order to allow cutter bits to move from the front face of the cutterhead into the cutter bit replacement chamber located inside the machine body, muck enters the guide rail through this opening to hinder movement of cutter bits.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-mentioned problems, and to provide a method for replacing cutters of a tunnel-excavating machine which facilitates cutter replacement operations and enables quick cutter replacement operations to thereby lessen burden imposed on workers and improve safety and work efficiency.
Another object of the present invention is to provide a method for excavating a tunnel which employs the method for replacing cutters.
Still another object of the present invention is to provide a tunnel-excavating machine which employs the method for replacing cutters.
To achieve the above object, the present invention provides a method for replacing cutters of a tunnel-excavating machine in which a plurality of columns of cutters connected one another are disposed on a front face of a cutterhead and which allows a column of cutters to be withdrawn into a machine body, the method comprising the steps of: withdrawing a column of cutters or a portion of the column of cutters into a cutter accommodation box supported by the machine body; replacing the cutters with other cutters; fixing a column of newly-loaded cutters at a predetermined position on the front face of the cutterhead; rotating the cutterhead until another column of cutters faces the cutter accommodation box; and repeating the withdrawing step, the replacing step, the fixing step, and the rotating step for sequential replacement of remaining columns of cutters.
Thus, all cutters can be replaced by means of a single set of the cutter accommodation box and a moving jack, thereby improving the efficiency of cutter replacement operations.
The present invention further provides a method for excavating a tunnel, comprising the step of replacing worn cutters with new cutters or replacing cutters with appropriate cutters according to geological ground conditions, by use of the above-described method for replacing cutters of a tunnel-excavating machine, so as to perform tunnel-excavating operations continuously.
Since tunnel-excavating operations can be performed continuously, the e
Mukaidani Tsunematsu
Sugiyama Masahiko
Mitsubishi Heavy Industries Ltd.
Tsay Frank S.
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