Patent Publication Number: US-8539656-B2

Title: Fastening tool

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a division of U.S. application Ser. No. 11/955,743, filed Dec. 13, 2007, and claims the benefit under 35 USC §119(a)-(d) of Japanese Application No. 2006-342077 filed Dec. 20, 2006, the entireties of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a fastening method of generating an axial force in a bolt so as to fasten a nut, and a fastening tool used for this method. 
     BACKGROUND OF THE INVENTION 
     Conventionally, as a fastening method, there has been a fastening method using a bolt and a nut. The fastening method using the bolt and the nut is structured such that an axial force (an elastic energy) stored in a shaft of the bolt acts as a force for pulling in an axial direction of the bolt on thread surfaces of the bolt and the nut, thereby preventing the bolt and the nut from being loosened on the basis of a friction force generated on the thread faces so as to fasten a fastened member. Accordingly, it is necessary to securely store the axial force in the shaft of the bolt, however, about 90% of a fastening torque is lost due to a friction between a seat surface of the nut and the fastened member and a friction of the thread surface at a time of screwing and fastening the nut to the bolt, and only about 10% of the fastening torque can store the axial force in the shaft of the bolt. As mentioned above, since it is impossible to sufficiently store the axial force in the shaft of the bolt, there has been a problem that the bolt and the nut are loosened due to a repeated load and a vibration applied to the fastened member. 
     Further, there are risks that the friction force between the seat surface of the nut and the fastened member and the friction force of the threaded portions are scattered, and the seat surface of the nut and the fastened member, and the threaded portions are gnawed or seized, whereby the axial force stored in the shaft of the bolt is not stable, and the bolt and the nut are loosened. Accordingly, in the case of fastening a high strength portion, there is employed a countermeasure of applying a friction coefficient stabilizing agent to a thread ridge of the bolt, thereby stabilizing the axial force of the bolt. Therefore, there is a problem that a cost is increased. 
     Accordingly, in the case that a detachment of the fastening is not allowed, there is used a non-disassemble swage method, as shown in U.S. Pat. No. 4,347,728. The non-dissemble swage method is a method of inserting a pin  51  having a parallel groove  51   a  formed on a surface of a shaft to a fastened member  52 , thereafter setting a collar  53  from a leading end  51   b  of the pin, caulking the collar  53  from both sides while pulling the leading end  51   b  of the pin by a special tool (not shown) and fastening the fastened member, as shown in  FIG. 18 . In accordance with this method, it is possible to securely apply the axial force to the pin  51 . However, in accordance with this non-assemble swage fastening method, since it is necessary to break the pin  51  and the collar  53  by the special tool at a time of detaching, there is a problem that the pin  51  and the collar  53  can not be reused, as well as a detaching work becomes complicated. 
     Accordingly, there has been proposed a swage fastening method as shown in Japanese Patent No. 2672190. The swage fastening method is a method of inserting a Hacks pin  61  (trade mark) in which a spiral lock groove  61   a  is formed as shown in  FIG. 19  in place of the parallel groove  51   a  to a fastened member  62 , setting a collar  63  from a leading end  61   b  of the pin, and caulking the collar  63  from both sides while pulling the leading end  61   b  of the pin by a special tool (not shown) so as to fasten the fastened member. 
     In the swage fastening method using the Hacks pin  61  (trade mark), it is possible to detach the collar  63  from the Hacks pin  61  (trade mark) by gripping the collar  63  so as to rotate without breaking the Hacks pin (trade mark) and the collar  63  at a time of detaching. However, since the collar  63  is caulked so as to be fastened, there has been a problem that the once detached collar  63  can not be reused. 
     Further, in the fastening methods mentioned above, since the collars  53  and  63  are plastically deformed so as to be caulked, it is assumed to use a soft material. In order to correspond to a high axial force, there has been a problem that it is necessary to set a height of the collars  53  and  63  high. Further, in the axial force fastening method, since the collars  53  and  63  are caulked, a surface treated layer such as a plating or the like applied to the surfaces of the collars  53  and  63  is scratched, and there has been a problem that a rust proofing countermeasure is necessary. 
     SUMMARY OF THE INVENTION 
     The present invention is finished by aiming to provide a fastening method and a fastening tool which solves the problems as mentioned above, securely and stably generates an axial force, prevents a bolt and a nut from being loosened due to a repeated load or vibration, does not require to apply a friction coefficient stabilizing agent to a thread ridge of the bolt, can be reused without any complicated detaching work, does not require to set a height of the nut high, and does not require any rust proofing countermeasure. 
     In order to solve the problems mentioned above, in accordance with the present invention, there is provided a fastening method of fastening a fastened member by a bolt and a nut, wherein the fastened member is fastened by inserting the bolt to the fastened member, thereafter temporarily fastening the nut and the bolt, pulling a shaft portion of the bolt in an axial direction of the bolt, rotating the nut so as to screw into the bolt while generating an axial force in the shaft portion of the bolt, and thereafter canceling the pulling of the bolt. 
     Alternatively, there is provided a fastening method of fastening a first fastened member in which a threaded hole is formed and a second fastened member in which a clearance hole is formed, wherein the first fastened member and the second fastened member are fastened by: screwing a nut into a stud bolt; integrating the stud bolt and the nut by a torque transmitting means by which the stud bolt and the nut do not rotate with each other at a predetermined low torque or less; pulling a leading end of the stud bolt in an axial direction of the stud bolt on a side into which the nut is screwed in, thereby the stud bolt is elastically deformed and an axial force is generated, while rotating and screwing the nut into the stud bolt; and finally canceling the pulling of the stud bolt. 
     In this case, it is preferable to have a state in which a gap is generated between a seat surface of the nut and the fastened member opposing to the seat surface, at a time of pulling the leading end of the shaft portion of the bolt in the axial direction of the bolt and rotating the nut so as to screw into the bolt. 
     In this case, in order to realize the invention mentioned above, there is provided a fastening tool comprising:
         a tubular fastening member rotating a nut;   a spindle member stored in an inner portion of the fastening member and pulling a shaft portion of a bolt or a leading end of a stud bolt in an axial direction; and   a pressing member pressing a fastened member on the basis of a reaction force applied to the spindle member and provided in an outer portion of the fastening member.       

     Further, it is preferable that an inner member is provided within the spindle member, the inner member being structures such that, if a leading end thereof is brought into contact with the leading end of the bolt or the leading end of the stud bolt, the rotation of the spindle member is stopped. 
     Further, it is preferable that an inner member is provided within the spindle member, the inner member being structured such that a leading end thereof engages with an engagement concave portion provided at the leading end of the bolt, slides in an axial direction, and rotates. 
     Further, it is preferable that the structure is made such as to stop the rotation of the spindle member if the leading end of the spindle member is screwed into a predetermined position from the leading end position of the inner member. 
     Further, it is preferable that an inner portion of the spindle member is provided with a fixing member in which a leading end thereof is engaged with an engagement concave portion provided in a leading end of the bolt so as to be slid in an axial direction and be prevented from rotating. 
     Alternatively, it is preferable that an inner portion of the spindle member is provided with a fixing member which is slid in an axial direction and has a leading end pressing the leading end of the bolt. 
     Further, it is preferable that the structure is made such as to stop the rotation of the spindle member if the leading end of the spindle member is screwed into a predetermined position from the leading end position of the fixing member. 
     Since the structure is made such as to pull the shaft portion of the bolt or the stud bolt in the axial direction of the bolt, generate the axial force in the stud bolt and screw the nut thereinto, it is possible to reduce the friction force between the threaded portion of the bolt and the threaded portion of the nut, and it is possible to securely and stably generate the axial force. Accordingly, it is possible to prevent the bolt and the nut from being loosened by the repeated load and vibration. Further, it is not necessary to coat the friction coefficient stabilizing agent to the thread ridge of the bolt for preventing the slack of the nut, and it is possible to make it unnecessary to set the height of the nut high. Further, since the surface treatment layer applied to the surface of the nut is not scratched at a time of fastening the nut, it is possible to make the rust proofing countermeasure unnecessary. Further, it is possible to provide the reusable fastening method and fastening tool without making the detaching work complicated. Further, it is possible to securely apply a desired axial force to the bolt and the stud bolt so as to fasten while monitoring the desired axial force by a load cell. 
     Further, since the structure is made such as to fasten the fastened member by canceling the pulling of the leading end of the bolt after screwing the nut into the bolt, the friction force is generated between the threaded portion of the bolt and the threaded portion of the nut on the basis of the axial force stored in the shaft portion of the bolt in the nut after being fastened, and the load pushing down in the axial direction is applied to the nut. Therefore the friction force is generated in the seat surface of the nut and the fastened member, and there can be provided the fastening method in which the nut is hard to be loosened. 
     In this case, on the assumption that there is provided a state in which the gap is generated between the seat surface of the nut and the fastened member opposing to the seat surface, at a time of pulling the leading end of the bolt or the stud bolt in the axial direction of the bolt, and rotating the nut so as to screw into the bolt or the stud bolt, the friction force is not generated between the seat surface of the nut and the fastened member opposing to the seat surface. Accordingly, it is possible to fasten while securely applying the axial force to the bolt or the stud bolt. 
     Further, in the case that the inner portion of the spindle member is provided with the inner member structured such that the rotation of the spindle member is stopped if the leading end thereof is brought into contact with the leading end of the bolt or the leading end of the stud bolt, the rotation of the spindle member is stopped if the leading end of the spindle member is screwed to the predetermined position from the leading end position of the inner member. Therefore, it is possible to prevent the spindle member from being brought into contact with the nut. 
     Further, in the case that the inner portion of the spindle member is provided with the inner member structured such that the leading end thereof is engaged with the engagement concave portion provided in the leading end of the bolt, is slid in the axial direction and is rotated, it is possible to temporarily fasten the bolt and the nut simply only by setting the fastening tool onto the nut, engaging the leading end of the inner member with the engagement concave portion, and rotating the inner member. 
     Further, in the case that the structure is made such as to stop the rotation of the spindle member if the leading end of the spindle member is screwed to the predetermined position from the leading end position of the inner member, it is possible to prevent the spindle member from being brought into contact with the nut. 
     Alternatively, in the case that the inner portion of the spindle member is provided with the fixing member in which the leading end thereof is engaged with the engagement concave portion provided in the leading end of the bolt, slides in the axial direction and does not rotate, the rotation of the bolt is blocked by inserting the leading end of the fixing member to the engagement concave portion of the bolt so as to engage. Accordingly, it is possible to prevent the nut and the bolt from rotating together. 
     Alternatively, in the case that the inner portion of the spindle member is provided with the fixing member which slides in the axial direction and has the leading end pressing the leading end of the bolt, it is possible to block the rotation of the bolt by pressing the leading end of the shaft portion of the bolt by the leading end of the fixing member at a time of screwing the threaded hole of the spindle member into the leading end of the bolt, and it is possible to prevent an idle rotation of the bolt. 
     Further, in the case that the structure is made such as to stop the rotation of the spindle member if the leading end of the spindle member is screwed to the predetermined position from the leading end position of the fixing member, it is possible to prevent the spindle member from being brought into contact with the nut. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory view showing a first embodiment; 
         FIG. 2  is an explanatory view showing the first embodiment; 
         FIG. 3  is an explanatory view showing the first embodiment; 
         FIG. 4  is an explanatory view showing the first embodiment; 
         FIG. 5  is an explanatory view showing the first embodiment; 
         FIG. 6  is an explanatory view showing the first embodiment; 
         FIG. 7  is an explanatory view showing the first embodiment; 
         FIG. 8  is an explanatory view showing a second embodiment; 
         FIG. 9  is an explanatory view showing a third embodiment; 
         FIG. 10  is an explanatory view showing a fourth embodiment; 
         FIG. 11  is an explanatory view showing a fifth embodiment; 
         FIG. 12  is an explanatory view showing the fifth embodiment; 
         FIG. 13  is an explanatory view showing the fifth embodiment; 
         FIG. 14  is an explanatory view showing the fifth embodiment; 
         FIG. 15  is an explanatory view showing the fifth embodiment; 
         FIG. 16  is an explanatory view showing the fifth embodiment; 
         FIG. 17  is an explanatory view showing the fifth embodiment; 
         FIG. 18  is an explanatory view showing a conventional swage fastening method (non-disassembly); and 
         FIG. 19  is an explanatory view showing the conventional swage fastening method (disassembly). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
     A description will be given below of a preferable embodiment (a first embodiment) of the present invention with reference to the accompanying drawings. 
     An engagement concave portion  21   f  depressed in as a hexagonal shape or the like is provided in a leading end of a shaft portion  21   c  of a bolt  21  used in the present invention. In this case, a nut  22  in accordance with the embodiment is constituted by a hexagonal nut. However, the nut  22  is not limited to the hexagonal nut, but may be constituted by any nut such as a square nut, a dodecagonal nut, a torque nut. 
     The bolt  21  is passed through a hole  20   a  of a fastened member  20 , and the nut  22  is lightly fastened to a leading end  21   b  of the bolt  21  (a state in  FIG. 1 ). 
     A fastening tool  10  used in the present invention is mainly constituted by a tubular fastening member  1 , a spindle member  2  stored in an inner portion of the fastening member  1 , an inner member  4  stored in an inner portion of the spindle member  2 , and a pressing member  3  provided in an outer portion of the fastening member  1 , as shown in  FIG. 2 . A leading end portion  1   a  of the fastening member  1  is structured such as to be engaged with the nut  22 . 
     The fastening member  1  is engaged with the nut  22 , the leading end of the inner member  4  is engaged with the engagement concave portion  21   f  of the bolt  21 , and the fastening tool  10  is set (a state in  FIG. 2 ). The bolt  21  and the nut  22  are temporarily fastened by rotating the inner member  4  so as to rotate the bolt  21  until a seat surface  21   g  of the bolt  21  comes into contact with the fastened member  20  (a state in  FIG. 3 ). At this time, since the inner member  4  is rotated while fixing the fastening member  1 , the nut  22  does not rotate together with the bolt  21 . 
     A threaded hole  2   a  engaging with a thread ridge of the bolt  21  is formed in a leading end of the spindle member  2 . The leading end  21   b  of the shaft portion  21   c  of the bolt  21  is gripped by rotating the spindle member  2  so as to screw the threaded hole  2   a  of the spindle member  2  into the leading end  21   b  of the shaft portion  21   c  of the bolt  21  (a state in  FIG. 4 ). At this time, in order to prevent the leading end of the spindle member  2  from being brought into contact with an upper end of the nut  22 , the structure is made such that the rotation of the spindle member  2  is stopped if the leading end of the spindle member  2  is screwed into a predetermined position a from a leading end position of the inner member  4 . In other words, the inner member  4  doubles as a role of a sensor stopping a spindle motor (not shown) rotating the spindle member  2 . In this case, the predetermined position “a” from the leading end position of the inner member  4  can be optionally set by the used bolt. 
     If the spindle member  2  pulls up the leading end  21   b  of the shaft portion  21   c  of the bolt  21 , the pressing member  3  presses the fastened member  20  on the basis of a reaction force of an inner portion of the fastening tool  10 . The fastened member  20  and the shaft portion  21   c  of the bolt  21  are respectively deformed elastically in opposite directions, and a gap is generated between the seat surface  22   a  of the nut  22  and the fastened member  20  opposing to the seat surface  22   a  (a state in  FIG. 5 ). If the fastening tool  10  is provided with a load cell (not shown) measuring an axial force of the bolt  21 , it is possible to securely apply a desired axial force to the bolt  21  while monitoring the desired axial force by the load cell. 
     In this state, the nut  22  is screwed into the bolt  21  by rotating the fastening member  1  so as to rotate the nut  22  until the seat surface  22   a  of the nut  22  seats on the fastened member  20  (a state in  FIG. 6 ). In this case, at a time of screwing the nut  22  into the bolt  21 , the seat surface  21   g  of the bolt  21  is pressed to the fastened member  20  on the basis of the axial force stored in the shaft portion  21   c  of the bolt  21  and a friction force is generated, whereby the bolt  21  rotates but does not rotate together with the nut  22 . Further, if the structure is made such as to fix the inner member  4  at a time of screwing the nut  22  into the bolt  21 , it is possible to more securely prevent the co-rotation. 
     If the pressing member  3  is thereafter got off from the fastened member  20 , the spindle member  2  is rotated in an opposite side to a fastening direction, and the spindle member  2  is got off from the leading end  21   b  of the bolt  21 , the fastening of the fastened member  20  is finished (a state in  FIG. 7 ). 
     A friction force is generated in a threaded portion  21   d  of the bolt  21  and a threaded portion  22   b  of the nut  22  on the basis of the axial force (an elastic energy and a strain energy) stored in an inner portion of the shaft portion  21   c  of the bolt  21 , whereby the bolt  21  and the nut  22  are hard to be loosened. Further, since a load pressing down in an axial direction is applied to the nut  22  on the basis of the axial force stored in the inner portion of the shaft portion  21   c  of the bolt  21 , the friction force is generated between the seat surface  22   a  of the nut  22  and the fastened member  20 , and the nut  22  is hard to be loosened. 
     As mentioned above, in the fastening method in accordance with the present invention, the structure is made such as to rotate the nut  22  until seating on the fastened member  20 , in the state in which the leading end  21   b  of the bolt  21  is pulled in the axial direction of the bolt  21 , the axial force is generated by elastically deforming the bolt  21  and the gap is generated between the fastened member  20  and the nut  22 . Accordingly, since it is possible to extremely reduce the friction force between the threaded portion  21   d  of the bolt  21  and the threaded portion  22   b  of the nut  22  at a time of fastening the nut  22  to the bolt  21 , and the friction force is not generated between the seat surface  22   a  of the nut  22  and the fastened member  20 , it is possible to rotate and fasten the nut  22  while applying a sufficient axial force to the bolt  21 . 
     In the fastening method in accordance with the present invention, the friction force between the threaded portion  21   d  of the bolt  21  and the threaded portion  22   b  of the nut  22  is small, and the friction force is not generated between the seat surface  22   a  of the nut  22  and the fastened member  20  opposing to the seat surface  22   a . Accordingly, it is possible to fasten the nut  22  by a low fastening torque. Therefore, it is possible to rotate and fasten the nut  22  without scratching a surface treatment layer for a rust proofing applied to a surface of the nut  22 , and it is not necessary to apply a rust proofing treatment after fastening the nut  22 . 
     Second Embodiment 
     Next,  FIG. 8  shows an explanatory view showing a second embodiment, and a description will be given of the second embodiment. In this second embodiment, a normal bolt  23  is used. In this case, the normal bolt  23  means a bolt in which the engagement concave portion  21   f  (the first embodiment) is not formed in the leading end of the shaft portion of the bolt. 
     The bolt  23  is passed through the hole  20   a  of the fastened member  20 , the nut  22  is thereafter screwed into the bolt  23  so as to be temporarily fastened until the seat surface  22   a  of the nut  22  comes into contact with the fastened member  20 , and the fastening tool  10  is set. The threaded hole  2   a  of the spindle member  2  is screwed into the leading end of the bolt  23  by rotating the spindle member  2 , and the spindle member  2  grips the bolt  23 . At this time, in order to prevent the leading end of the spindle member  2  from being brought into contact with the upper end of the nut  22 , the structure is made such that if the leading end of the spindle member  2  is screwed to a predetermined position “b” from the leading end position of the inner member  4 , the rotation of the spindle member  2  is stopped. In other words, the inner member  4  doubles as a role of a sensor stopping a spindle motor (not shown) rotating the spindle member  2 . In this case, the predetermined position “b” from the leading end position of the inner member  4  can be optionally set by the used bolt  22  and bolt  23 . The fastening method after gripping the leading end of the bolt  23  by the spindle member  2  is the same as the first embodiment. 
     Third Embodiment 
     Next, a description will be given of a third embodiment. A fastening tool used in this third embodiment basically has the same structure as the fastening tool  10  used in the first embodiment, however, is structured such that the inner portion of the spindle member  2  is provided with a fixing member  5  in which a leading end thereof is engaged with the engagement concave portion  21   f  provided in the leading end  21   b  of the bolt  21  so as to be slid in an axial direction, in place of the inner member  4 . In this case, the fixing member  5  is not rotated as is different from the inner member  4  in accordance with the first embodiment. 
     In this third embodiment, the bolt  21  is passed through the hole  20   a  of the fastened member  20 , the nut  22  is thereafter screwed into the bolt  21  so as to be temporarily fastened until the seat surface  22   a  of the nut  22  comes into contact with the fastened member  20 , and the fastening tool  11  is set. At this time, the leading end of the fixing member  5  is inserted to the engagement concave portion  21   f  of the bolt  21 , and the leading end of the bolt  23  is gripped by rotating the spindle member  2  from the leading end of the fixing member  5  to a predetermined position “c”, and screwing the threaded hole  2   a  of the spindle member  2  to the leading end of the bolt  23  (a state in  FIG. 9 ). The fixing member  5  also doubles as a role of the sensor stopping the spindle motor (not shown) rotating the spindle member  2 . In this case, the predetermined position “c” from the leading end position of the fixing member  5  can be optionally set by the used bolt. 
     A gap is generated between the seat surface  22   a  of the nut  22  and the fastened member  20  opposing to the seat surface  22   a  by pulling up the leading end  21   b  of the shaft portion  21   c  of the bolt  21  by the spindle member  2 . In this state, the nut  22  is screwed into the bolt  21  by rotating the fastening member  1  so as to rotate the nut  22  until the seat surface  22   a  of the nut  22  seats on the fastened member  20 . In this third embodiment, since the fixing member  5  is engaged with the engagement concave portion  21   f  of the bolt  21  at a time of screwing the nut  22  into the bolt  21  by the fastening member  1 , thereby preventing the bolt  21  from being rotated, it is possible to prevent the co-rotation of the bolt  21  and the nut  22 . As mentioned above, in accordance with the third embodiment, even in the case that the head portion  21   a  of the bolt  21  can not be gripped by a spanner or the like, such as a case that the head portion  21   a  of the bolt  21  is formed as a spherical crown shape, a case that a space for inserting the tool such as the spanner or the like is not provided around the head portion  21   a  of the bolt  21  and the like, it is possible to prevent the co-rotation of the bolt  21  and the nut  22 . 
     Fourth Embodiment 
       FIG. 10  shows an explanatory view of a fourth embodiment, and a description will be given of the fourth embodiment. In this fourth embodiment, the normal bolt  23  is used. In this case, the normal bolt  23  means a bolt in which the engagement concave portion  21   f  (the first embodiment and the third embodiment) is not formed in the leading end of the shaft portion of the bolt. 
     A fastening tool  12  used in the fourth embodiment basically has the same structure as the fastening tool  10  used in the first embodiment, however, is structured such that the inner portion of the spindle member  2  is provided with a fixing member  6  sliding in an axial direction, in place of the inner member  4 . In this case, the fixing member  6  does not rotate as is different from the inner member  4  in accordance with the first embodiment. The fourth embodiment corresponds to an embodiment which prevents a co-rotation of the bolt  23  by pressing a leading end  23   c  of a shaft portion  23   b  of the bolt  23  by the leading end of the fixing member  6 , at a time of screwing the threaded hole  2   a  of the spindle member  2  into the leading end  23   c  of the bolt  23 . 
     In the fourth embodiment, the bolt  23  is passed through the hole  20   a  of the fastened member  20 , the nut  22  is thereafter screwed into the bolt  23  so as to be temporarily fastened until the seat surface  22   a  of the nut  22  comes into contact with the fastened member  20 , and the fastening tool  11  is set. Next, the fixing member  6  is slid to the leading end  23   c  side of the bolt  23 , and the leading end  23   b  of the shaft portion  23   b  of the bolt  23  is pressed by the leading end of the fixing member  6 . The leading end of the bolt  23  is gripped by rotating the spindle member  2  to a predetermined position “d” from the leading end of the fixing member  6 , and screwing the threaded hole  2   a  of the spindle member  2  to the leading end  23   c  of the bolt  23  (a state in  FIG. 10 ). At this time, since the leading end  23   c  of the bolt  23  is pressed by the leading end of the fixing member  6 , the friction force is generated between the thread ridges of the bolt  23  and the nut  22 , and between the seat surface  22   a  of the nut  22  and the fastened member  20 , and it is possible to securely screw the threaded hole  2   a  of the spindle member  2  into the leading end  23   c  of the bolt  23  without the bolt  23  idle rotating. 
     The fixing member  6  also doubles as the sensor stopping the spindle motor (not shown) rotating the spindle member  2 . In this case, the predetermined position “d” from the leading end position of the fixing member  6  can be optionally set by the used bolt. 
     A gap is generated between the seat surface  22   a  of the nut  22  and the fastened member  20  opposing to the seat surface  22   a , by pulling up the leading end  23   c  of the shaft portion  23   b  of the bolt  23  by the spindle member  2 . In this state, the fastening member  1  is rotated, the nut  22  is rotated until the seat surface  22   a  of the nut  22  seats on the fastened member  20 , and the nut  22  is screwed into the bolt  23 , whereby the fastening work is finished. 
     Fifth Embodiment 
     Next, a description will be given of a fifth embodiment. The fifth embodiment corresponds to a method of fastening a first fastened member  25  in which a threaded hole  25   a  is formed, and a second fastened member  26  in which a clearance hole  26   a  is formed, by a stud bolt  27  and a nut  28 , as shown in  FIG. 11 . 
     In this embodiment, the structure is made such that a torque transmitting means  29  is formed by deforming a threaded portion of one of the stud bolt  27  and the nut  28 , and the nut  28  is screwed into the stud bolt  27  so as to be integrated, whereby the stud bolt  27  and the nut  28  do not rotate with each other at a predetermined low fastening torque or less. In this case, the torque transmitting means  29  may be structured by applying an adhesive material such as a Nylok (trade mark) or the like to the threaded portion of one of the stud bolt  27  and the nut  28 . 
     The second fastened member  26  is arranged on the first fastened member  25  in such a manner that the clearance hole  26   a  is arranged coaxially with the threaded hole  25   a , and the stud bolt  27  and the nut  28  integrated by the torque transmitting means  29  are temporarily fastened to the threaded hole  25   a  of the second fastened member  25  (a state in  FIG. 12 ). At this time, since the stud bolt  27  and the nut  28  are not rotated at the predetermined low fastening torque by the torque transmitting means  29 , it is possible to rotate the nut  28  so as to screw the stud bolt  27  into the threaded hole  25   a.    
     The leading end  1   a  of the fastening member  1  is engaged with the nut  28  so as to set the fastening tool  10 , the fastening member  1  is rotated, and the stud bolt  27  is screwed until the seat surface  28   a  of the nut  28  is brought into contact with the second fastened member  26  (a state in  FIG. 13 ). In this case, if the seat surface  28   a  of the nut  28  is brought into contact with the second fastened member  26 , the fastening torque of the fastening member  1  is increased, and the rotation of the fastening member  1  is stopped. In this case, since the stud bolt  27  and the nut  28  are not rotated at the predetermined low fastening torque by the torque transmitting means  29  as mentioned above, until the leading end of the stud bolt  27  is brought into contact with a bottom portion of the threaded hole  25   a  of the first fastened member  25  (the state in  FIG. 12 ), it is possible to rotate the nut  28  so as to screw the stud bolt  27  into the threaded hole  25   a . On the other hand, if the leading end of the stud bolt  27  is brought into contact with the bottom portion of the threaded hole  25   a  of the first fastened member  25  (the state in  FIG. 12 ), the torque transmitting means  29  is broken at the predetermined torque or more. Therefore, the nut  28  is rotated. 
     If the seat surface  28   a  of the nut  28  is brought into contact with the second fastened member  26 , and the rotation of the nut  28  is stopped (the state in  FIG. 13 ), the spindle member  2  automatically starts rotating while moving down, the threaded hole  2   a  of the spindle member  2  is screwed into the leading end  27   a  of the stud bolt  27 , and the spindle member  2  grips the leading end  27   a  of the stud bolt  27  (a state in  FIG. 14 ). At this time, in order to prevent the leading end of the spindle member  2  from being brought into contact with the upper end of the nut  28 , the structure is made such that if the leading end of the inner member  4  is brought into contact with the leading end  27   a  of the stud bolt  27 , and the leading end of the spindle member  2  is screwed to a predetermined position “e” from the leading end position of the inner member  4 , the rotation of the spindle member  2  is stopped. In other words, the inner member  4  doubles as the role of the sensor stopping the spindle motor (not shown) rotating the spindle member  2 . In this case, the predetermined position “e” form the leading end position of the inner member  4  can be optionally set by the used bolt  28  or the stud bolt  27 . 
     If the leading end  27   a  of the stud bolt  27  is pulled up by the spindle member  2 , the pressing member  3  presses the second fastened member  26  on the basis of a reaction force in the inner portion of the fastening tool  10 , whereby the second fastened member  26  and the stud bolt  27  are elastically deformed respectively in opposite directions (a state in  FIG. 15 ). In this state, a gap is generated between the seat surface  28   a  of the nut  28 , and the second fastened member  26  opposing to the seat surface  28   a.    
     If the fastening member  1  is rotated in this state, the stud bolt  27  is not rotated, but the nut  28  is rotated, because the friction force is generated between the threaded hole  25   a  and the threaded portion of the stud bolt  27  on the basis of the axial force. The nut  28  is rotated until the seat surface  28   a  of the nut  28  seats on the second fastened member  25 , and the nut  28  is screwed into the stud bolt  27  (a state in  FIG. 16 ). 
     Thereafter, if the spindle member  2  is rotated in the opposite direction to the fastening direction after removing the pulling force of the spindle member  2 , and the spindle member  2  is detached form the leading end  27   a  of the stud bolt  27  by detaching the pressing member  3  form the second fastened member  26 , the fastening between the first fastened member  25  and the second fastened member  26  is finished (a state in  FIG. 17 ). 
     The friction force is generated between the stud bolt  27  and the threaded hole  25   a  of the fastened member  25 , and between the stud bolt  27  and the threaded portion of the nut  28 , on the basis of the axial force (the elastic energy and the strain energy) stored in the stud bolt  27 , whereby the stud bolt  27  and the nut  28  are hard to be loosened. Further, since the pushing down load is applied to the nut  28  in the axial direction on the basis of the axial force stored in the stud bolt  27 , the friction force is generated in the seat surface  28   a  of the nut  28  and the second fastened member  25 , and the nut  28  is hard to be loosened. 
     The present invention is described above in connection with the embodiments which seem to be most practical and preferable at this time. However, the present invention is not limited to the embodiments disclosed in the specification of the present invention, but can be appropriately modified within the range which does not go counter to the contents or concept of the invention readable from the claims and the whole specification. The fastening method and the fastening tool having such the modification should be understood to be included within the technical range. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           1  fastening member 
           1   a  leading end portion 
           2  spindle member 
           2   a  threaded hole 
           3  pressing member 
           4  inner member 
           5  fixing member (third embodiment) 
           6  fixing member (fourth embodiment) 
           10  fastening tool (first embodiment, second embodiment and fifth embodiment 
           11  fastening tool(third embodiment) 
           12  fastening tool(fourth embodiment) 
           20  fastened member 
           20   a  hole 
           21  bolt (first embodiment) 
           21   a  head portion 
           21   b  leading end 
           21   c  shaft portion 
           21   d  threaded portion 
           21   e  head portion (second embodiment) 
           21   f  engagement concave portion 
           21   g  seat surface 
           22  nut 
           22   a  seat surface 
           22   b  threaded portion 
           23  bolt (second embodiment and fourth embodiment) 
           23   a  head portion 
           23   b  shaft portion 
           23   c  leading end 
           24  bolt (third embodiment) 
           25  first fastened member 
           25   a  threaded hole 
           26  second fastened member 
           26   a  clearance hole 
           27  stud bolt 
           27   a  leading end 
           27   b  leading end 
           28  nut 
           28   a  seat surface 
           29  torque transmitting means 
           51  pin 
           51   a  parallel groove 
           52  fastened member 
           53  pin 
           61  Hacks pin (trade mark) 
           61   a  parallel groove 
           61   b  leading end of pin 
           62  fastened member 
           63  collar 
           61  pin 
           61   a  parallel groove 
           61   b  leading end of pin 
           62  fastened member 
           63  collar 
         a predetermined position from leading end position of inner member (first embodiment) 
         b predetermined position from leading end position of inner member (second embodiment) 
         c predetermined position from leading end position of inner member (third embodiment) 
         d predetermined position from leading end position of inner member (fourth embodiment) 
         e predetermined position from leading end position of inner member (fifth embodiment)