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CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2004-137704 filed on May 6, 2004; the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to a cutting edge apparatus used for tunnel excavation, and in particular to a cutting edge apparatus which facilitates driving of a cutting edge into a ground.  
         [0003]     Conventionally, excavation for a tunnel with a relatively small diameter (a diameter up to about several meters) has been performed by workers&#39; hand drilling. In this case, the cutting edge positioned at the distal end of a Hume pipe is propelled by a propelling apparatus such as a hydraulic jack to be driven into the ground. Workers drill the ground and remove soil produced from the cutting face of a tunnel to excavate a tunnel.  
         [0004]     In the tunnel excavation, the cutting face may collapse. The collapse causes a large amount of soil to enter the cutting edge, thereby risking workers&#39; safety and rendering working in front of the cutting edge difficult.  
         [0005]     A cutting edge apparatus that ensures safe tunnel excavation even when there is a risk, such as collapse of a cutting face, has been proposed (see Japanese Patent Application Laid-open No. 2002-242584, for example).  
         [0006]     In the cutting edge apparatus, the cylindrical outer pipe has a cutting edge to be driven into the ground at the distal end thereof. The outer pipe has a tapered conical main unit vibrated by a vibration motor therein. When the cutting face of the tunnel collapses, deposition of soil in the conical main unit allows for safe tunnel excavation, which is considerably effective for safety ensuring.  
         [0007]     In the above structure, vibrations of the conical main unit caused by the vibration motor reduce friction between the conical main unit and fallen soil, thus easily correcting propelling and directionality of the cutting edge apparatus.  
         [0008]     Furthermore, the cutting edge and the conical main unit are provided separately from each other for easy replacement of a worn cutting edge.  
         [0009]     In the above structure, however, driving of the cutting edge into a firm ground requires a large force, and the structure should be further improved.  
       SUMMARY OF THE INVENTION  
       [0010]     The aspect of the invention provides a cutting edge apparatus. The apparatus includes a cylindrical outer pipe to be driven into a ground. The apparatus includes a vibratable vibration cylinder provided within the outer pipe and being movable relative to the outer pipe in an axial direction of the outer pipe. The apparatus includes a cutting edge member substantially identical in outer size with the outer pipe and being integrally mounted to the outer circumference of the end of the vibration cylinder. The apparatus includes a vibrator mounted to the vibration cylinder and configured to vibrate the vibration cylinder. The vibration cylinder has a tapered rear portion so that the rear portion becomes smaller in size as the rear portion extends toward the rear end of the vibration cylinder.  
         [0011]     The cutting edge member may have a distal end coated with a hard material.  
         [0012]     The cutting edge apparatus may include a lubrication supplier configured to supply a lubricant to the outer pipe or the outer circumferential surface of a following pipe provided at the back of the outer pipe.  
         [0013]     The cutting edge member may be fixed to the outer circumference of the end of the vibration cylinder.  
         [0014]     The invention allows for excavation of a tunnel, vibrating the cutting edge member. This way facilitates driving of the cutting edge member into a ground. This way allows the tapered portion of the cutting edge member to receive the fallen soil during falling of the cutting face of the tunnel, thus ensuring safety.  
     
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0015]      FIG. 1  is a sectional view of a cutting edge apparatus according to an embodiment of the invention;  
         [0016]      FIG. 2  is a plan sectional view of the cutting edge apparatus shown in  FIG. 1 ;  
         [0017]      FIG. 3  is a right side view of the cutting edge apparatus and the following pipe as viewed from arrows III-A and III-B in  FIG. 1 , where the left half as indicated by III-A illustrates the cutting edge apparatus, and the right half as indicated by III-B illustrates the following pipe; and  
         [0018]      FIG. 4  is a schematic view illustrating excavation facilities using the cutting edge apparatus shown in  FIG. 1 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     With reference to  FIG. 1 , a cutting edge apparatus  1  according to an embodiment of the invention includes a cylindrical outer pipe  5  driven in a ground  3  by a propelling apparatus such as hydraulic jacking cylinders  127   a  and  127   b  (see  FIG. 4 ). The cutting edge apparatus  1  includes a vibration cylinder  7  mounted inside the outer pipe  5  to be movable in an axial direction of the outer pipe  5  and be capable of vibrating.  
         [0020]     In more detail, the vibration cylinder  7  includes an inner pipe  11  supported within the outer cylinder  5  via an annular sealing member  9  to be movable in an axial direction and be capable of vibrating. The front end of the inner pipe  11  is integrally welded to a stopper ring  13 . The stopper ring  13  abuts against a stopper  15  provided on the inner face of the outer pipe  5  to restrict the vibration cylinder  7  to movement in a forward direction (the left direction in  FIG. 1 ).  
         [0021]     The front end of the stopper ring  13  is integrally fixed, by welding or the like, to the rear end of a taper ring  17  whose diameter gradually increases toward the front end thereof. The outer periphery of the front end of the taper ring  17  is integrally welded to a guide ring  19  with an outer diameter slightly smaller than the inner diameter of the outer pipe  5 . The guide ring  19  has an outer peripheral face projecting from the front end face (the left end face in  FIG. 1 ) of the outer pipe  5 . The outer peripheral face is integrally welded to a ring-like cutting edge member  21  with an outer diameter approximately equal to that of the outer pipe  5 . The rear end face (a right end face in  FIG. 1 ) of the cutting edge member  21  serves as an abutting face that is abutable relatively against the front end face of the outer pipe  5 . The rear end of the cutting edge member  21  and the front end of the outer pipe  5  have an allowance  20  therebetween.  
         [0022]     That is, when the propelling apparatus pushes against the outer pipe  5  in a forward direction, the front end face of the outer pipe  5  and the rear end face of the cutting edge member  21  abut against each other to drive the cutting edge member  21  into the ground  3 . The step portion between the taper ring  17  and the guide ring  19  and the step portion between the guide ring  19  and the cutting edge member  21  are welded in a taper shape. The taper shape eliminates the step portion to allow for smooth driving of the cutting edge member  21  into the ground. The annular front end face of the cutting edge member  21  is coated with an appropriate hard material  23  having excellent wear resistance and impact resistance, such as alloy tool steel, high-speed steel, or hard metal by spraying.  
         [0023]     The structure allows tunnel excavation even if the ground  3  is firm, and achieves a long life of the cutting edge member  21 .  
         [0024]     The rear portion of the inner pipe  11  gradually decreases in diameter toward the rear end. The rear portion of the inner pipe  11  is integrally welded to a taper body  25 . The taper body  25  with a tapered cylindrical shape has a circular opening portion  25   a  at the rear end portion, and the area of the opening portion  25   a  is about a fourth (¼) of a circular area surrounded by the cutting edge member  21 . The opening portion  25   a  with a small diameter of the taper body  25  is attached with a lid  29  to be openable and closable using a hinge  27  (see  FIG. 2 ). The opening portion  25   a  has a lock handle  31  (see  FIG. 4 ) that locks the lid  29  to a closed state thereof.  
         [0025]     The taper body  25  is vibratably supported to the outer pipe  5  by elastic members  33  such as rubbers provided at a plurality of portions on the inner peripheral face on the outer cylinder  5 . The taper body  25  is mounted with vibrators  35  such as vibration motors, which applies vibrations to the taper body  25 . The outer peripheral face of the taper body  25  has an abutting member  39  fixed thereon. The rear end portion of the abutting member  39  is abutable against the front face of a ring-like bracket  37  provided on the inner peripheral face of the outer pipe  5 .  
         [0026]     A clearance  38  between the bracket  37  and the abutting member  39  is set to be approximately equal to a clearance  20  between the front end face of the outer pipe  5  and the rear end face of the cutting edge member  21 . When the outer pipe  5  and the cutting edge member  21  abut against each other to push forward (propel) the cutting edge member  21 , the bracket  37  abuts against the abutting member  39  to push forward the taper body  25 . That is, the cutting edge member  21  and the taper body  25  are integrally pushed forward in synchronization with each other. The structure disperses portions being pushed, while the cutting edge member  21  is being pushed forward by the outer pipe  5 , thereby suppressing stress.  
         [0027]     The rear end of the outer pipe  5  has a following pipe  41  for propelling (pushing forward) the outer pipe  5 . In detail, the outer diameter of the following pipe  41  is slightly smaller than an outer diameter of the outer pipe  5 . The front end portion of the following pipe  41  abuts against an annular abutting member  43  provided on the inner peripheral face of the outer pipe  5  near the rear end thereof. The outer peripheral face of the distal end portion of the following pipe  41  and the inner peripheral face of the outer pipe  5  have an annular sealing member  45  made from rubber mounted therebetween.  
         [0028]     The inner peripheral face of the following pipe  41  near the rear end has an annular distal end face abutting member  49  to be pushed forward by the distal end face of the Hume pipe  47 . The annular chamber  51  is formed at the front side (the left side in  FIG. 1 ) of the distal end face abutting member  49 . The chamber  51  reserves lubricant. The inner peripheral face of the chamber  51  is formed with a plurality of supplying ports  53  for supplying lubricant. The inner peripheral face  51  has an inspection port  59  that is closed by a lid member  57  attachable or detachable by a fixing tool  55  such as a plurality of bolts.  
         [0029]     The outer peripheral face of the following pipe  41  has an annular opening member  63  corresponding to the chamber  51 . The opening member  63  is provided with opening portions  61  (see  FIG. 2 ) opened so as to be enlarged rearward and formed along a circumferential direction thereof at proper intervals. The outer peripheral face of the opening member  63  is covered with an annular cover  65 . The opening portions  61  have communication holes  67  opened to the following pipe  41  and communicating with the chamber  51 .  
         [0030]     When lubricant such as oil is properly supplied from the supplying ports  53  into the chamber  51 , lubricant in the chamber  51  is supplied to the opening portions  61  so that lubricant is supplied on the outer peripheral face of the Hume pipe  47  through the opening portions  61 . Thereby, while the Hume pipe  47  is being pushed forward by a propelling apparatus such as a hydraulic jack, friction between the Hume pipe  47  and the ground  3  is made small, thereby facilitating pushing of the Hume pipe  47 . The condition of the lubricant in the chamber  51  is confirmed through the inspection port  59 . When, for example, lubricant has been consolidated, detachment of the lid member  57  permits the lubricant to be easily taken out of the chamber  51 .  
         [0031]     In the structure, when the propelling apparatus pushes forward against the Hume pipe  47 , the Hume pipe  47  pushes against the following pipe  41  and the following pipe  41  pushes against the outer pipe  5 . When the outer pipe  5  is pushed forward, the distal end face (the front end face) of the outer pipe  5  abuts against the cutting edge member  21  to be pushed forward, thus driving the cutting edge member  21  into the ground  3 .  
         [0032]     During the driving-into, when the vibrators  35  are driven to vibrate the taper body  25 , integral provision of the taper body  25  and the cutting edge member  21  allows integral vibrations thereof. Thereby, the cutting edge member  21  is driven while being vibrated to the ground  3 . Even if the ground  3  is firm, effective driving is allowed to improve efficiency.  
         [0033]     When the cutting edge member  21  is driven into the ground  3 , the lid  29  is held in a closed state thereof, considering collapse of a cutting face of the ground  3 . After the cutting edge member  21  is driven into the ground  3 , the lid  29  is opened. The cutting edge member  21  then excavates the cutting face of the ground  3  in a surrounded state, thus excavating a tunnel.  
         [0034]     After soil produced by excavation is ejected from the taper body  25 , the propelling apparatus drives the cutting edge member  21  into the ground  3  again. Repetition of this work continuously performs tunnel excavation.  
         [0035]     As understood from the descriptions, the taper body  25  and the cutting edge member  21  integrally provided vibrate integrally. This vibration facilitates driving of the cutting edge member  21  into the firm ground  3  as compared with the conventional system. When a large amount of fallen soil is present inside the taper body  25 , the vibration reduces friction between fallen soil and the taper body  25 , thus facilitating directional correction of the cutting edge member  21 .  
         [0036]     The coating of the hard material  23  on the distal end portion of the cutting edge member  21  enhances wear resistance and impact resistance, thereby, allowing for the long life in the cutting edge member  21 .  
         [0037]     Further, the following pipe  41  has the lubricant supplying ports which supply lubricant to the outer peripheral face of the Hume pipe  47 , thus reducing friction occurring during pushing of the Hume pipe  47  forward.  
         [0038]     The structure is applied to the outer pipe  5 , and the lubricant supplying ports may be provided in the outer pipe  5 .  
         [0039]     With reference to  FIG. 4 , excavation facilities  100  to which the cutting edge apparatus  1  is applied will be described.  
         [0040]     The excavation facilities  100  include a cutting edge apparatus  1  which excavates the ground  3 . The excavation facilities  100  include a jacking pipe  101  serving as a Hume pipe  47  communicating with the cutting edge apparatus  1 . The end of the jacking pipe  101  projects above the pit floor  121  within a pit  113 . The excavation facilities  100  include a battery feeder  103  feeding power to the vibrators  35 . The excavation facilities  100  include a compressed air-mixer  105  and a flexible pipe  107  connected to the compressed air-mixer  105  in the jacking pipe  101 . The excavation facilities  100  include a vacuum pump  109  connected to the flexible pipe  107 . Soil produced by excavation is conveyed by a truck  111 .  
         [0041]     The excavation facilities  100  include an adapter  123  mounted at the end of the jacking pipe  101  in the pit  113 . The excavation facilities  100  include a reaction wall  125  provided on the side wall of the pit  113 . The excavation facilities  100  include jacking cylinders  127   a  and  127   b  serving as a propelling apparatus arranged between the reaction wall  125  and the adapter  123 .  
         [0042]     The excavation facilities  100  include a generator  131  and a power pack  133  for supplying power to the battery feeder  103 . The excavation facilities  100  include, outside the pit  113 , a lubrication pump  135  serving as a lubricant supplying section, which supplies lubricant to the jacking pipe  101 . A hydraulic crane  137  which conveys, for example, jacking pipes  101 , is put on standby outside the pit  113 .  
         [0043]     A method of operating the excavation facilities  100  will be described.  
         [0044]     When the jacking cylinders  127   a  and  127   b  push against the jacking pipe  101  forward, the jacking pipe  101  pushes against the outer pipe  5  of the cutting edge apparatus  1  to drive the cutting edge member  21  into the ground  3 . During the driving-into, the lubrication pump  135  supplies lubricant to the outer face of the jacking pipe  101 .  
         [0045]     The generator  131  supplies power to the vibrators  35  via the battery pack  133  and the battery feeder  103 . The vibrators  35  vibrate the cutting edge member  21  as well as the vibration cylinder  7 . The cutting edge member  21  excavates a tunnel in the ground  3 .  
         [0046]     Soil produced by excavation is sucked up on a ground via the flexible pipe  107  by the vacuum pump  109 , and it is loaded on the truck  111 .  
         [0047]     When the cutting edge apparatus  1  goes into the ground  3  at a fixed distance, a new jacking pipe is hung down in the pit  113  by the hydraulic crane  137 . The new jacking pipe is set to the end of the jacking pipe  101  in use.  
         [0048]     Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art, in light of the above teachings. The scope of the invention is defined with reference to the following claims.

Summary:
A cutting edge apparatus includes a cylindrical outer pipe to be driven into a ground. The apparatus includes a vibratable vibration cylinder provided within the outer pipe and being movable relative to the outer pipe in an axial direction of the outer pipe. The apparatus includes a cutting edge member substantially identical in outer size with the outer pipe and being integrally mounted to the outer circumference of the end of the vibration cylinder. The apparatus includes a vibrator mounted to the vibration cylinder and configured to vibrate the vibration cylinder. The vibration cylinder has a tapered rear portion so that the rear portion becomes smaller in size as the rear portion extends toward the rear end of the vibration cylinder.