Abstract:
The disclosure herein discloses a rebar tying tool that ties plural rebars using a wire. The rebar tying tool includes a housing and a twisting motor, and may include a twisting mechanism that twists the wire around the plural rebars by the twisting motor. The twisting mechanism may include a screw shaft, a gripping member that grips the wire in cooperation with rotation of the screw shaft, a first reduction mechanism that reduces and transmits rotation of the twisting motor to a relay shaft, and a second reduction mechanism that reduces and transmits rotation of the relay shaft to the screw shaft. The first reduction mechanism may be a coaxial reduction mechanism, and the second reduction mechanism may be a parallel-axis reduction mechanism.

Description:
TECHNICAL FIELD 
       [0001]    A technique disclosed herein relates to a rebar tying tool. 
       BACKGROUND ART 
       [0002]    Japanese Patent Application Publication No. 2010-185184 discloses a rebar tying tool that ties plural rebars using a wire. The rebar tying tool is provided with a housing, a feeding mechanism that feeds the wire by rotation of a feeding motor from a reel on which the wire is wound, a guide mechanism that guides the wire fed from the feeding mechanism around the plural rebars, a cutting mechanism that cuts the wire fed from the feeding mechanism, and a twisting mechanism that twists the wire around the plural rebars by rotation of a twisting motor. 
       SUMMARY 
       [0003]    The present disclosure aims to provide an improved rebar tying tool. 
         [0004]    The disclosure herein discloses a rebar tying tool configured to tie plural rebars using a wire. The rebar tying tool may comprise a housing and a twisting mechanism provided with a twisting motor and configured to twist the wire around the plural rebars by the twisting motor. The twisting mechanism may further comprise a screw shaft, a gripping member configured to grip the wire in cooperation with rotation of the screw shaft, a first reduction mechanism configured to reduce and transmit rotation of the twisting motor to a relay shaft, and a second reduction mechanism configured to reduce and transmit rotation of the relay shaft to the screw shaft. The first reduction mechanism may be a coaxial reduction mechanism, and the second reduction mechanism may be a parallel-axis reduction mechanism. Notably, the coaxial reduction mechanism described herein refers to a reduction mechanism in which an input shaft and an output shaft are disposed on a same line, and for example, it may be a planetary gear mechanism or the like. Further, the parallel-axis reduction mechanism described herein refers to a reduction mechanism in which an input shaft and an output shaft are respectively disposed on lines that are parallel to each other, and for example, it may be a spur gear reduction mechanism, a helical gear-type reduction mechanism, a belt-type reduction mechanism, or the like. 
         [0005]    A portion in a vicinity of a rear end of the screw shaft comes to be positioned in a vicinity of a center of a body portion of the rebar tying tool. Due to this, if the coaxial reduction mechanism is used as the second reduction mechanism for transmitting the rotation to the screw shaft, the coaxial reduction mechanism a size of which is large must be disposed in the vicinity of the center of the body portion of the rebar tying tool, which casts large restriction on an internal layout of the rebar tying tool. According to the above configuration, the parallel-axis reduction mechanism a size of which is small is used as the second reduction mechanism for transmitting the rotation to the screw shaft. Further, in the above configuration, the large-sized coaxial reduction mechanism is disposed at a position offset from a central portion by the parallel axis reduction mechanism. Due to this, a space in the vicinity of the center of the body portion of the rebar tying tool can be secured, and a degree of freedom in the internal layout of the rebar tying tool can be improved. 
         [0006]    Another rebar tying tool disclosed herein comprises a reel on which a wire is wound, and a feeding motor configured to feed the wire, wherein the rebar tying tool is configured to tie plural rebars using the wire by feeding the wire from the reel by the feeding motor, guiding the wire around the plural rebars, and twisting the wire around the plural rebars. The rebar tying tool may comprise a first housing plate, and a second housing plate configuring an outer surface of the rebar tying tool and covering the reel and the feeding motor. The reel and the feeding motor are disposed between the first housing plate and the second housing plate. 
         [0007]    In the above rebar tying tool, the rebar tying tool can be completed by assembling the reel and the feeding motor on the first housing, after which the second housing is assembled thereon. An assembly workability of the rebar tying tool can be improved as compared to a case of covering the reel and the feeding motor respectively by separated housing plates. 
         [0008]    Yet another rebar tying tool disclosed herein comprises a feeding motor configured to feed a wire, and a twisting motor configured to twist the wire, wherein the rebar tying tool is configured to tie plural rebars using the wire by feeding the wire by the feeding motor, guiding the wire around the plural rebars, and twisting the wire around the plural rebars by the twisting motor. The rebar tying tool comprises a housing plate, and a control board configured to control the feeding motor and the twisting motor. The feeding motor is disposed on one side as seen from the housing plate. The twisting motor is disposed on the other side as seen from the housing plate. A part of the control board is disposed on the one side as seen from the housing plate, and another part of the control board is disposed on the other side as seen from the housing plate. 
         [0009]    In the above rebar tying tool, a wire connection between the feeding motor and the control board can be performed in a space on the one side as seen from the housing plate, and a wire connection between the twisting motor and the control board can be performed in a space on the other side as seen from the housing plate. Since no connection wire needs to be passed from the one side to the other side of the housing plate, no hole and no connection terminal for passing the connection wire needs to be provided. Further, since the connection wire does not need to be passed from the one side to the other side of the housing plate, the assembly workability of the rebar tying tool can be improved. 
         [0010]    Yet another rebar tying tool disclosed herein comprises a twisting motor configured to twist a wire, wherein the rebar tying tool is configured to tie plural rebars using the wire by feeding the wire, guiding the wire around the plural rebars, and twisting the wire around the plural rebars by the twisting motor. The rebar tying tool comprises a housing plate, a brake mechanism configured to brake the wire feeding, and a control board configured to control the brake mechanism and the twisting motor. The brake mechanism is disposed an one side as seen from the housing plate. The twisting motor is disposed on the other side as seen from the housing plate. A part of the control board is disposed on the one side as seen from the housing plate, and another part of the control board is disposed on the other side as seen from the housing plate. 
         [0011]    In the above rebar tying tool, a wire connection between the brake mechanism and the control board can be performed in a space on the one side as seen from the housing plate, and a wire connection between the twisting motor and the control board can be performed in a space on the other side as seen from the housing plate. Since no connection wire needs to be passed from the one side to the other side of the housing plate, no hole and no connection terminal for passing the connection wire needs to be provided. Further, since the connection wire does not need to be passed from the one side to the other side of the housing plate, the assembly workability of the rebar tying tool can be improved. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0012]      FIG. 1  is a perspective view showing an outer appearance of a rebar tying tool  2  of an embodiment, 
           [0013]      FIG. 2  is a perspective view showing an internal structure of a tying tool body  4  of the rebar tying tool  2  of the embodiment, 
           [0014]      FIG. 3  is a perspective view showing an outer appearance of a feeding mechanism  32  of the rebar tying tool  2  of the embodiment, 
           [0015]      FIG. 4  is a cross sectional view showing the internal structure of the tying tool body  4  of the rebar tying tool  2  of the embodiment, 
           [0016]      FIG. 5  is a perspective view showing the internal structures of the tying tool body  4  and a grip  6  of the rebar tying tool  2  of the embodiment, 
           [0017]      FIG. 6  is a perspective view showing a state in which a lower curl guide  62  of the rebar tying tool  2  of the embodiment is opened, 
           [0018]      FIG. 7  is a perspective view showing a state in which the lower curl guide  62  of the rebar tying tool  2  of the embodiment is closed, 
           [0019]      FIG. 8  is a view showing a contact piece  80   a  of a state detection mechanism  78  and a state detection opening  80   d  of a left outer housing  14  of the rebar tying tool  2  of the embodiment, 
           [0020]      FIG. 9  is a perspective view showing an off state of a brake mechanism  36  of the rebar tying tool  2  of the embodiment, 
           [0021]      FIG. 10  is a perspective view showing an on state of the brake mechanism  36  of the rebar tying tool  2  of the embodiment, 
           [0022]      FIG. 11  is a view showing a brake arm  92  of the brake mechanism  36  and a brake opening  92   a  of an inner housing  16  of the rebar tying tool  2  of the embodiment, 
           [0023]      FIG. 12  is a perspective view showing a twisting mechanism  40  of the rebar tying tool  2  of the embodiment, 
           [0024]      FIG. 13  is a cross sectional perspective view showing an internal structure of a first reduction mechanism  98  of the rebar tying tool  2  of the embodiment, 
           [0025]      FIG. 14  is a cross sectional perspective view showing an internal structure of a second reduction mechanism  100  of the rebar tying tool  2  of the embodiment, 
           [0026]      FIG. 15  is a perspective view showing a grip mechanism  102  of the rebar tying tool  2  of the embodiment, 
           [0027]      FIG. 16  is a perspective view showing a screw shaft  120 , a distal shaft  132 , a right hook  134 , and a left hook  136  of the rebar tying tool  2  of the embodiment, 
           [0028]      FIG. 17  is a perspective view showing the right hook  134  and the left hook  136  of the rebar tying tool  2  of the embodiment, 
           [0029]      FIG. 18  is a perspective view showing a rotation restricting mechanism  156  of the rebar tying tool  2  of the embodiment, 
           [0030]      FIG. 19  is a cross sectional perspective view showing an operation of the grip mechanism  102  of the rebar tying tool  2  of the embodiment, 
           [0031]      FIG. 20  is a cross sectional perspective view showing the operation of the grip mechanism  102  of the rebar tying tool  2  of the embodiment, 
           [0032]      FIG. 21  is a cross sectional perspective view showing the operation of the grip mechanism  102  of the rebar tying tool  2  of the embodiment, 
           [0033]      FIG. 22  is a cross sectional perspective view showing the operation of the grip mechanism  102  of the rebar tying tool  2  of the embodiment, 
           [0034]      FIG. 23  is a perspective view showing an assembling work of the rebar tying tool  2  of the embodiment, 
           [0035]      FIG. 24  is a perspective view showing the assembling work of the rebar tying tool  2  of the embodiment, 
           [0036]      FIG. 25  is a perspective view showing the assembling work of the rebar tying tool  2  of the embodiment, 
           [0037]      FIG. 26  is a perspective view showing the assembling work of the rebar tying tool  2  of the embodiment, and 
           [0038]      FIG. 27  is a perspective view showing the assembling work of the rebar tying tool  2  of the embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    In one or more embodiments, a twisting mechanism may be unitized. 
         [0040]    According to the above configuration, the twisting mechanism can easily be installed upon assembling a rebar tying tool. 
         [0041]    In one or more embodiments, the twisting mechanism may further comprise a distal shaft coupled with a gripping member via a cam mechanism; a sleeve coupled with a screw shaft via a rotary-linear motion converting mechanism, and into a front end side of which the distal shaft is inserted and into a rear end side of which the screw shaft is inserted; and a bumper disposed between the distal shaft and the screw shaft inside the sleeve. 
         [0042]    According to the above configuration, as compared to a configuration in which the bumper is disposed on the rear end side of the sleeve, a size of the twisting mechanism in a vicinity of a rear end of the screw shaft can be made small. Due to this, a degree of freedom in a layout in a vicinity of a center of a body portion of the rebar tying tool can be improved. 
         [0043]    In one or more embodiments, the rotary-linear motion converting mechanism may be a ball screw mechanism. 
         [0044]    According to the above configuration, rotary motion of the screw shaft can be converted to linear motion by an inexpensive configuration. 
         [0045]    In one or more embodiments, the rebar tying tool may further comprise a feeding mechanism provided with a feeding motor, and configured to feed a wire using the feeding motor from a reel on which the wire is wound; and a brake mechanism configured to stop rotation of the reel. The brake mechanism may comprise a brake arm configured to engage with the reel; an actuator and a link coupling the brake arm and the actuator. The brake mechanism may be unitized. 
         [0046]    According to the above configuration, the brake mechanism can easily be installed upon assembling the rebar tying tool. 
         [0047]    In one or more embodiments, the reel may be disposed inside a reel chamber of a housing, the brake mechanism may be disposed inside a brake chamber of the housing, a wall of the housing defining the reel chamber may comprise a brake opening through which the brake arm passes, and the brake chamber may communicate with outside of the brake chamber only through the brake opening. 
         [0048]    According to the above configuration, foreign matter can be suppressed from entering into the brake chamber. The brake mechanism and other mechanisms existing around the brake mechanism can be prevented from being affected by the foreign matter. 
         [0049]    In one or more embodiments, the actuator may be disposed behind the feeding motor but in font of the reel, and the feeding motor, the actuator, and the reel may be disposed so as to overlap with each other in a front-and-rear direction. 
         [0050]    According to the above configuration, the actuator of the brake mechanism is disposed in a dead space formed when the feeding motor and the reel are disposed along the front-and-rear direction, and thus the rebar tying tool can be made smaller in size. 
         [0051]    In one or more embodiments, the rebar tying tool may further comprise a feeding mechanism provided with a feeding motor, and configured to feed a wire using the feeding motor from a reel on which the wire is wound. The housing may comprise a first outer housing; a second outer housing; and an inner housing disposed to be intervened between the first outer housing and the second outer housing. A twisting motor may be disposed in a space defined by the first outer housing and the inner housing, the feeding motor may be disposed in a space defined by the inner housing and the second outer housing, a twisting motor retaining portion configured to retain the twisting motor may be provided on a surface of the first outer housing facing the inner housing, and a feeding motor retaining portion configured to retain the feeding motor may be provided on a surface of the inner housing facing the second outer housing. 
         [0052]    According to the above configuration, the twisting motor of the twisting mechanism is retained by the twisting motor retaining portion of the first outer housing and disposed in the space defined by the first outer housing and the inner housing, and the feeding motor of the feeding mechanism is retained by the feeding motor retaining portion of the inner housing and disposed in the space defined by the inner housing and the second outer housing. Upon assembling the rebar tying tool with the above configuration, firstly the twisting mechanism is installed onto the first outer housing, subsequently the inner housing is installed thereon, subsequently the feeding mechanism is installed onto the inner housing, and subsequently the second outer housing is installed thereon. According to the above configuration, the twisting mechanism including the twisting motor and the feeding mechanism including the feeding motor can both be installed by work from one side (that is, a second outer housing side) of the rebar tying tool. Due to this, assembling workability of the rebar tying tool can further be improved. 
         [0053]    In one or more embodiments, the rebar tying tool may further comprise a guide mechanism configured to guide the wire around plural rebars. The guide mechanism may comprise an upper curl guide configured to guide the wire above the plural rebars; and a lower curl guide configured to guide the wire under the plural rebars such that the wire is guided into the lower curl guide from the upper curl guide. The lower curl guide may be openably supported on the housing. The rebar tying tool may further comprise a state detecting mechanism configured to detect whether a state of the lower curl guide is opened or closed. The state detection mechanism may comprise a contact piece, and may be configured to detect whether the state of the lower curl guide is opened or closed by detecting a contact between the contact piece and the lower curl guide. The housing may be provided with a state detection opening through which the contact piece passes, and a width of the state detection opening may be substantially equal to a width of the contact piece. 
         [0054]    According to the above configuration, the state detection opening that needs to be provided on the housing to detect whether the state of the lower curl guide is opened or closed can be made as small as possible. Due to this, foreign matter can be prevented from entering through the state detection opening into an inside of the rebar tying tool. 
         [0055]    Representative non-limiting examples of the present disclosure will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the disclosure. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide further improved rebar tying tools, as well as methods of using and manufacturing the same. 
         [0056]    Moreover, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the present disclosure in the broadest sense, and are instead taught merely to particularly describe representative examples of the disclosure. Furthermore, various features of the above-described and below-described representative examples, as well as various features of independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. 
         [0057]    All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter. 
       Embodiment 
       [0058]    A rebar tying tool  2  of an embodiment will be described with reference to the drawings. The rebar tying tool  2  shown in  FIG. 1  is a power tool for tying plural rebars R using a wire W. 
         [0059]    The rebar tying tool  2  comprises a tying tool body  4 , a grip  6  provided below the tying tool body  4 , and a battery attachment  8  provided below the grip  6 . A trigger  7  is provided at a front upper portion of the grip  6 . A battery B is detachably attached below the battery attachment  8  via a terminal  9  (see  FIGS. 24 to 27 ). 
         [0060]    The rebar tying tool  2  comprises a housing  3 . The housing  3  comprises a right outer housing  12 , a left outer housing  14 , and an inner housing  16 . The right outer housing  12  is integrally structured with a right half surface of the tying tool body  4 , a right half surface of the grip  6 , and a right half surface of the battery attachment  8 . The left outer housing  14  is integrally structured with a left half surface of the tying tool body  4 , a left half surface of the grip  6 , and a left half surface of the battery attachment  8 . The right outer housing  12  and the left outer housing  14  configure an outer surface of the rebar tying tool  2 . The inner housing  16  is configured in a shape that intervenes between the right outer housing  12  and the left outer housing  14  in an area from an upper portion to an intermediate portion of an inside of the tying tool body  4 . Each of the right outer housing  12 , the left outer housing  14 , and the inner housing  16  can be termed a housing plate. The inside of the tying tool body  4  is partitioned into a space defined by the left outer housing  14  and the inner housing  16 , and a space defined by the right outer housing  12  and the inner housing  16 . The space defined by the left outer housing  14  and the inner housing  16  and the space defined by the right outer housing  12  and the inner housing  16  communicate at a lower portion of the tying tool body  4 . Further, a reel chamber  19  that houses a reel  10  (see  FIG. 2 ) is provided on a rear side of the tying tool body  4 . The reel chamber  19  is defined, in its rightward direction, by the right outer housing  12 , and is defined, in its leftward, downward, and forward directions, by the inner housing  16 . The reel chamber  19  is covered, in its upward direction, by an openable cover  17 . 
         [0061]    A first operation and display unit  18  is provided on an upper surface of the tying tool body  4 . The first operation and display unit  18  comprises a first operation and display unit board  21  (see  FIGS. 5, 24, and 25 ) provided with a main switch  20  for switching power of the rebar tying tool  2  between on and off and a main power LED  22  for displaying an on/off state of the power of the rebar tying tool  2 , and a first switch plate  23  that covers the main switch  20  and the main power LED  22  of the first operation and display unit board  21 . A second operation and display unit  24  is provided on a front upper surface of the battery attachment  8 . The second operation and display unit  24  comprises a second operation and display unit board  25  (see  FIGS. 24 to 27 ) provided with setting buttons  26  for setting a feed amount of the wire W and twisting strength for the wire W and a display  28  for displaying contents set by the setting buttons  26 , and a second switch plate  27  that covers the setting buttons  26  and the display  28  of the second operation and display unit board  25 . The terminal  9  to which the battery B is connected, the trigger  7 , the first operation and display unit board  21 , and the second operation and display unit board  25  are connected to a control board  180  to be described later. 
         [0062]    The tying tool body  4  mainly comprises an accommodating mechanism  30 , a feeding mechanism  32 , a guide mechanism  34 , a brake mechanism  36 , and the control board  180  shown in  FIG. 2 , a cutting mechanism  38  shown in  FIG. 4 , and a twisting mechanism  40  shown in  FIG. 5 . Notably, in  FIG. 2 , the right outer housing  12 , the cover  17 , and connection wires and the like inside the rebar tying tool  2  are not shown for easier view of the drawing. For the same purpose, in  FIG. 4 , the connection wires inside the rebar tying tool  2  are not shown. Further, for the same purpose, in  FIG. 5 , the left outer housing  14  and a part of the connection wires inside the rebar tying tool  2  are not shown. The control board  180  is disposed at a lower center portion of the tying tool body  4  so as to extend across the inner housing  16 . A part of the control board  180  is disposed on one side as seen from the inner housing  16  (right outer housing  12  side), and another part of the control board  180  is disposed on the other side as seen from the inner housing  16  (left outer housing  14  side). 
         [0063]    As shown in  FIG. 2 , the accommodating mechanism  30  detachably retains the reel  10  on which the wire W is wound. The reel  10  is rotatably supported by the accommodating mechanism  30  in the reel chamber  19 . 
         [0064]    The feeding mechanism  32  feeds out the wire W supplied from the reel  10  in the accommodating mechanism  30  to the guide mechanism  34  located on a front side of the tying tool body  4 . The feeding mechanism  32  comprises a guiding member  42 , a base member  43 , a feeding motor  44 , a driving gear  46 , a reduction mechanism  47 , a driven gear  48 , a releasing lever  50 , a compression spring  52  (see  FIG. 3 ), a lever holder  54  (see  FIG. 3 ), and a lock lever  56 . The feeding mechanism  32  is unitized, and is attached to the inner housing  16 . The guiding member  42  comprises a tapered penetrating hole  42   a  having a wide rear end and a narrow tip end. The guiding member  42  is fixed to the base member  43 . The driving gear  46  and the driven gear  48  are disposed more forward than the guiding member  42 . The driving gear  46  is coupled to the feeding motor  44  via the reduction mechanism  47 , and is rotated by being driven by the feeding motor  44 . The feeding motor  44  is connected to the control board  180  by the connection wire (not shown). The control board  180  is configured to control an operation of the feeding motor  44 . On a lateral surface of the driving gear  46 , a V-shaped groove  46   a  which extends along a circumferential direction of the driving gear  46  at a center in its height direction is provided. As shown in  FIG. 3 , the driven gear  48  is rotatably supported by a gear arm  50   a  of the releasing lever  50 . On a lateral surface of the driven gear  48 , a V-shaped groove  48   a  which extends along a circumferential direction of the driven gear  48  at a center in its height direction is provided. The releasing lever  50  is a substantially L-shaped member that comprises the gear arm  50   a  and an operation arm  50   b . The releasing lever  50  is pivotaly supported by the base member  43  via a pivot shaft  50   c . The operation arm  50   b  of the releasing lever  50  is coupled to a spring receiving portion  54   a  of the lever holder  54  via the compression spring  52 . The lever holder  54  is fixed by being clamped between the inner housing  16  and the left outer housing  14 . The compression spring  52  biases the operation arm  50   b  in a direction away from the spring receiving portion  54   a . Normally, torque acting in a direction that causes the driven gear  48  to approach the driving gear  46  is applied to the releasing lever  50  by biasing force of the compression spring  52 , and the driven gear  48  is pressed against the driving gear  46 . Due to this, teeth on the lateral surface of the driven gear  48  and teeth on the lateral surface of the driving gear  46  are engaged, and the wire W is held between the V-shaped groove  46   a  of the driving gear  46  and the V-shaped groove  48   a  of the driven gear  48 . When the feeding motor  44  rotates the driving gear  46  in this state, the driven gear  48  rotates in an opposite direction to the rotation direction of the driving gear  46 , and the wire W held by the driving gear  46  and the driven gear  48  is fed out to the guide mechanism  34 , and thus the wire W is drawn out from the real  10 . 
         [0065]    The lock lever  56  is pivotaly supported by the lever holder  54  via a pivot shaft  56   a . The lock lever  56  is biased in a direction along which the lock lever  56  contacts with the operation arm  50   b  of the releasing lever  50  by a torsion spring that is not shown. On the lock lever  56 , a recess  56   b  that engages with an tip of the operation arm  50   b  of the releasing lever  50  is provided. 
         [0066]    When a user of the rebar tying tool  2  presses in the operation arm  50   b  against the biasing force of the compression spring  52 , the releasing lever  50  pivots about the pivot shaft  50   c  and the driven gear  48  separates from the driving gear  46 . At this occasion, the lock lever  56  pivots about the pivot shaft  56   a  and the end portion of the operation arm  50   b  engages with the recess  56   b , resulting in the operation arm  50   b  being retained in the pressed-in state. Upon setting the wire W extending from the reel  10  in the feeding mechanism  32 , the user presses in the operation arm  50   b  to separate the driven gear  48  from the driving gear  46 , and in that state, positions an end of the wire W drawn out from the reel  10  between the driving gear  46  and the driven gear  48  through the penetrating hole  42   a  of the guiding member  42 . Then, when the user pivots the lock lever  56  in a direction along which the lock lever  56  separates away from the operation arm  50   b , the releasing lever  50  pivots about the pivot shaft  50   c  and the driven gear  48  engages with the driving gear  46 , and the wire W is held between the V-shaped groove  46   a  of the driving gear  46  and the V-shaped groove  48   a  of the driven gear  48 . 
         [0067]    As shown in  FIGS. 4 and 5 , the guide mechanism  34  guides the wire W fed from the feeding mechanism  32  around the rebars R in a circular shape. The guide mechanism  34  comprises a guiding pipe  58 , an upper curl guide  60 , and a lower curl guide  62 . The guiding pipe  58  and the upper curl guide  60  are unitized, and are attached to front sides of the left outer housing  14  and the inner housing  16 . A rearward end portion of the guiding pipe  58  is open toward an interface between the driving gear  46  and the driven gear  48 . The wire W fed from the feeding mechanism  32  is fed into the guiding pipe  58 . A forward end portion of the guiding pipe  58  is open toward an inside of the upper curl guide  60 . The upper curl guide  60  is provided with a first guiding passage  64  for guiding the wire W fed from the guiding pipe  58 , and a second guiding passage  66  for guiding the wire W fed from the lower curl guide  62 . 
         [0068]    As shown in  FIG. 4 , the first guiding passage  64  is provided with a plurality of guiding pins  68  for guiding the wire W so as to provide a downward curving profile to the wire W, and a cutter  70  constituting a part of the cutting mechanism  38  to be described later. The wire W fed from the guiding pipe  58  is guided by the guiding pins  68  in the first guiding passage  64 , passes through the cutter  70 , and is fed out from a forward end of the upper curl guide  60  toward the lower curl guide  62 . 
         [0069]    As shown in  FIG. 5 , the lower curl guide  62  is provided with a third guiding passage  72  and guarding plates  74 . The third guiding passage  72  comprises a right-side guiding wall  72   a  and a left-side guiding wall  72   b  for guiding the wire W fed from the forward end of the upper curl guide  60 . The guarding plates  74  have a shape extending upward on both sides of the third guiding passage  72 , and prevent the plural rebars R from interfering with the twisting mechanism  40  as well as foreign matter from entering into the tying tool body  4 . Further, the guarding plates  74  prevent the wire W from wiggling left and right upon when the twisting mechanism  40  twists the wire W wound in the circular shape. The wire W guided by the lower curl guide  62  is fed toward the second guiding passage  66  of the upper curl guide  60 . 
         [0070]    The second guiding passage  66  of the upper curl guide  60  is provided with an upper-side guiding wall  76  that guides the wire W fed from the lower curl guide  62  and feeds the wire W from the forward end of the upper curl guide  60  toward the lower curl guide  62 . 
         [0071]    The lower curl guide  62  is attached to the front sides of the left outer housing  14  and the inner housing  16 . The lower curl guide  62  is pivotaly supported by the left outer housing  14  and the inner housing  16  via a pivot shaft  62   a . The lower curl guide  62  can pivot between an opened state shown in  FIG. 6  and a closed state shown in  FIG. 7 . Notably, in  FIGS. 6 and 7 , the left outer housing  14  and the connection wires and the like inside the rebar tying tool  2  are not shown for easier view of the drawings. The lower curl guide  62  is biased in a closing direction by a torsion spring  62   b . When the rebar tying tool  2  is used, the lower curl guide  62  is in the closed state. If the wire W is tangled onto the twisting mechanism  40  during the use of the rebar tying tool  2 , the user can open the lower curl guide  62  and remove the tangled wire W on the twisting mechanism  40 . 
         [0072]    A state detection mechanism  78  configured to detect whether the lower curl guide  62  is in the opened state or the closed state is provided at a front lower portion inside the tying tool body  4 . The state detection mechanism  78  is attached to the left outer housing  14 . The state detection mechanism  78  comprises a state detection lever  80 , a torsion spring  82 , and a sensor board  84 . The sensor board  84  is connected to the control board  180  by a connection wire (not shown). The state detection lever  80  comprises a contact piece  80   a  and a detection piece  80   b . The state detection lever  80  is pivotaly supported by the left outer housing  14  via a pivot shaft  80 . As shown in  FIG. 8 , the contact piece  80   a  protrudes to an outside of the tying tool body  4  through a state detection opening  80   d  provided in the left outer housing  14 . Notably, in  FIG. 8 , the upper curl guide  60  and the lower curl guide  62  are not shown for easier view of the drawing. The detection piece  80   b  shown in  FIGS. 6 and 7  is provided with a permanent magnet (not shown). The sensor board  84  is fixed to the left outer housing  14 . A magnetic sensor (not shown) such as a Hall element is provided on a surface of the sensor board  84  facing the detection piece  80   b . As shown in  FIG. 6 , when the lower curl guide  62  is in the opened state, the state detection lever  80  pivots by biasing force of the torsion spring  82  and the permanent magnet of the detection piece  80   b  is positioned at a position away from the magnetic sensor of the sensor board  84 . If the lower curl guide  62  is closed from the above state, a contact piece  62   c  provided at a rear portion of the lower curl guide  62  makes contact with the contact piece  80   a  of the state detection lever  80 , and the state detection lever  80  pivots by the contact piece  80   a  of the state detection lever  80  being pressed down, as a result of which the permanent magnet of the detection piece  80   b  comes to be positioned at a position facing the magnetic sensor of the sensor board  84 . A signal detected by the magnetic sensor of the sensor board  84  is inputted to the control board  180 . The rebar tying tool  2  can determine whether the lower curl guide  62  is in the opened state or the closed state based on the detected signal of the magnetic sensor of the sensor board  84 . 
         [0073]    As shown in  FIG. 8 , a width of the state detection opening  80   d  in a left-and-right direction provided on the left outer housing  14  is substantially equal to a width of the contact piece  80   a  of the state detection lever  80  in the left-and-right direction. By configuring as such, the foreign matter can be prevented from entering into the tying tool body  4  through the state detection opening  80   d . Further, a width of the state detection opening  80   d  in an up-and-down direction provided on the left outer housing  14  is substantially equal to a movable range of the contact piece  80   a . By configuring as such, the foreign matter can be prevented from entering into the tying tool body  4  through the state detection opening  80   d.    
         [0074]    As shown in  FIG. 1 , the upper curl guide  60  feeds out the wire W from a forward upper side of the plural rebars R downward, and the lower curl guide  62  feeds out the wire W fed from the upper curl guide  60  from a rearward lower side of the plural rebars R upward. Due to this, the wire W fed from the feeding mechanism  32  is wound in the circular shape around the plural rebars R. When the feeding mechanism  32  feeds out a feed amount of the wire W set by the user, it stops the feeding motor  44  to terminate the feeding of the wire W. 
         [0075]    The brake mechanism  36  shown in  FIG. 2  stops rotation of the reel  10  in conjunction with the stop of the feeding of the wire W by the feeding mechanism  32 . The brake mechanism  36  comprises a solenoid  86 , a link  88  (see  FIGS. 9 and 10 ), a torsion spring  90  (see  FIGS. 9 and 10 ), and a brake arm  92 . The solenoid  86  of the brake mechanism  36  is connected to the control board  180  by a connection wire (not shown). The control board  180  is configured to control an operation of the brake mechanism  36 . The brake mechanism  36  is unitized, and is attached to the inner housing  16 . The reel  10  is provided with engaging portions  10   a  with which the brake arm  92  engages, and provided at predetermined angle intervals in a circumferential direction of the reel  10 . As shown in  FIG. 9 , in a state where the solenoid  86  is not energized, the brake arm  92  is separated away from the engaging portions  10   a  of the reel  10  by biasing force of the torsion spring  90 . As shown in  FIG. 10 , in a state where the solenoid  86  is energized, the brake arm  92  pivots toward the reel  10  by the link  88 , and the brake arm  92  engages with one of the engaging portions  10   a  of the reel  10 . When the feeding of the wire W is performed by the feeding mechanism  32 , the brake mechanism  36  does not energize the solenoid  86  to separate away the brake arm  92  from the engaging portions  10   a  of the reel  10 . Due to this, the reel  10  can freely rotate, and the feeding mechanism  32  can draw out the wire W from the reel  10 . Further, when the feeding of the wire W by the feeding mechanism  32  is stopped, the brake mechanism  36  energizes the solenoid  86  to engage the brake arm  92  with one of the engaging portions  10   a  of the reel  10 . Due to this, rotation of the reel  10  is inhibited. According to the above, it can be prevented that the wire W becomes loose between the reel  10  and the feeding mechanism  32  by the reel  10  continuing to rotate by inertia even after the feeding mechanism  32  had stopped feeding out the wire W. 
         [0076]    As shown in  FIG. 2 , the brake mechanism  36  is housed in a brake chamber  37  which is inside the tying tool body  4  and defined by the right outer housing  12  and the inner housing  16 . As shown in  FIG. 11 , the inner housing  16  is provided with a brake opening  92   a  through which a tip of the brake arm  92  passes. When the brake arm  92  is to be engaged with one of the engaging portions  10   a  of the reel  10 , only the tip of the brake arm  92  passes through the brake opening  92   a  and engages with one of the engaging portions  10   a  of the reel  10  via the brake opening  92   a . A width of the brake opening  92   a  in the left-and-right direction is substantially equal to a width of the tip of the brake arm  92 . Further, a width of the brake opening  92   a  in the front-and-rear direction is substantially equal to a movable range of the tip of the brake arm  92 . By configuring as such, the foreign matter can be prevented from entering into the tying tool body  4  through the brake opening  92   a . Further, the brake chamber  37  communicates with an outside of the brake chamber  37  only via the brake opening  92   a . By configuring as such, the foreign matter can be prevented from entering into the brake chamber  37 . The brake mechanism  36  and other mechanisms existing around the brake mechanism  36  can be prevented from being affected by the foreign matter. 
         [0077]    The cutting mechanism  38  shown in  FIG. 4  cuts the wire W in a state where the wire W is wound around the rebars R. The cutting mechanism  38  comprises the cutter  70  and a link  94 . The link  94  rotates the cutter  70  in cooperation with the twisting mechanism  40  to be described later. The wire W passing an inside of the cutter  70  is cut by the rotation of the cutter  70 . 
         [0078]    The twisting mechanism  40  shown in  FIG. 5  ties the plural rebars R with the wire W by twisting the wire W wound around the plural rebars R. As shown in  FIG. 12 , the twisting mechanism  40  comprises a twisting motor  96 , a first reduction mechanism  98 , a second reduction mechanism  100 , and a grip mechanism  102 . The twisting motor  96  is connected to the control board  180  by a connection wire (not shown). The control board  180  is configured to control an operation of the twisting motor  96 . The twisting mechanism  40  is unitized, and is attached to the left outer housing  14 . 
         [0079]    As shown in  FIG. 13 , the first reduction mechanism  98  is a planetary gear reduction mechanism. The first reduction mechanism  98  comprises a gear bracket  104 , an internal gear  106 , planetary gears  108 , and a sun gear  110 . The gear bracket  104  is fixed to a main bracket  112  (see  FIG. 12 ). The internal gear  106  is fixed to the gear bracket  104 . The sun gear  110  is coupled to an output shaft of the twisting motor  96 . The planetary gears  108  are coupled to a relay shaft  114  (see  FIG. 14 ) via a planetary carrier (not shown). The first reduction mechanism  98  reduces rotation of the twisting motor  96  and transmits the same to the relay shaft  114 . 
         [0080]    As shown in  FIG. 14 , the second reduction mechanism  100  is a spur gear reduction mechanism. The second reduction mechanism  100  comprises a first spur gear  116  and a second spur gear  118 . The first spur gear  116  is coupled to the relay shaft  114 . The second spur gear  118  is coupled to a screw shaft  120 . The second reduction mechanism  100  reduces rotation of the relay shaft  114  and transmits the same to the screw shaft  120 . 
         [0081]    As shown in  FIGS. 15 to 17 , the grip mechanism  102  comprises the screw shaft  120 , an inner sleeve  122  (see  FIGS. 19 to 22 ), an outer sleeve  124 , a push plate  126 , a push sleeve  128  (see  FIGS. 19 to 22 ), a supporting sleeve  130 , a distal shaft  132 , a right hook  134 , and a left hook  136 . 
         [0082]    As shown in  FIG. 16 , the screw shaft  120  has its rear side configured as a large diameter portion  120   a , and its front side configured as a small diameter portion  120   b . A spiral ball groove  120   c  is provided on an outer surface of the large diameter portion  120   a . A bumper  138  constituted of a circular elastic material is provided at a portion with a diameter difference between the large diameter portion  120   a  and the small diameter portion  120   b . A compression spring  140  is provided around the small diameter portion  120   b . The compression spring  140  biases the distal shaft  132  in a direction separating away from the bumper  138 . Further an engaging groove  120   d  (see  FIGS. 19 to 22 ) with which a stopper  142  of the distal shaft  132  engages is provided at a tip end of the small diameter portion  120   b.    
         [0083]    The inner sleeve  122  shown in  FIGS. 19 to 22  is a cylindrical member into which the screw shaft  120  is to be inserted. The inner sleeve  122  is provided with a ball hole (not shown) in which a bell  144  shown in  FIG. 16  is to fit. The screw shaft  120  and the inner sleeve  122  are coupled via the ball  144  fitted between the ball groove  120   c  and the ball hole. That is, the screw shaft  120  and the inner sleeve  122  are coupled via a bell screw. In a range where the ball groove  120   c  is provided, the inner sleeve  122  moves in the front-and-rear direction relative to the screw shaft  120  when the screw shaft  120  relatively rotates with respect to the inner sleeve  122 . 
         [0084]    As shown in  FIG. 15 , the outer sleeve  124  is a cylindrical member into which the inner sleeve  122  and the distal shaft  132  are to be inserted. The outer sleeve  124  is fixed to the inner sleeve  122  by a fixation screw  146 . 
         [0085]    The right hook  134  and the left hook  136  constitute a gripping member for gripping the wire W. As shown in  FIG. 15 , the left hook  136  is pivotaly supported on the outer sleeve  124  via a pivot shaft  136   a . As shown in  FIG. 16 , the left hook  136  is provided with a cam groove  136   b . Similarly, the right hook  134  is pivotaly supported on the outer sleeve  124  via a pivot shaft  134   a . The right hook  134  is provided with a cam groove  134   b  (see  FIG. 17 ). As shown in  FIG. 15 , the distal shaft  132  is slidably inserted in the outer sleeve  124 . The distal shaft  132  is provided with a cam pin  148  that engages with the cam groove  134   b  of the right hook  134  and the cam groove  136   b  of the left hook  136 . As shown in  FIG. 17 , when the distal shaft  132  relatively moves forward with respect to the outer sleeve  124 , the right hook  134  and the left hook  136  pivot in a direction which allows the cam pin  148  to come out from the cam grooves  134   b  and  136   b , resulting in the right hook  134  and the left hook  136  being in an opened state. Notably, in a state where the right hook  134  and the left hook  136  are opened to their maximum degree, a stopper portion  134   c  provided in the right hook  134  and a stopper portion  136   c  provided in the left hook  136  make contact with each other, and the right hook  134  and the left hook  136  cannot be opened any further. As a result, the distal shaft  132  is inhibited from moving forward any further relative to the outer sleeve  124 . When the distal shaft  132  relatively moves backward with respect to the outer sleeve  124 , the right hook  134  and the left hook  136  pivot so that the cam pin  148  enters into the cam grooves  134   b  and  136   b , resulting in the right hook  134  and the left hook  136  being in a closed state. As shown in  FIGS. 19 to 22 , the distal shaft  132  is provided with the stopper  142  that engages with the engaging groove  120   d  of the screw shaft  120 . The distal shaft  132  is allowed to move relatively in the front-and-rear direction with respect to the screw shaft  120  within a range defined by the stopper  142  engaging with a front end and a rear and of the engaging groove  120   d.    
         [0086]    As shown in  FIGS. 19 to 22 , the push sleeve  128  is a cylindrical member covering a periphery of the inner sleeve  122 . The push sleeve  128  is held between a rib  122   a  provided at a rear end of the inner sleeve  122  and the outer sleeve  124 . The push sleeve  128  is rotatable relative to the inner sleeve  122 . The push plate  126  is held between a rib  128   a  provided on the push sleeve  128  and the outer sleeve  124 . As shown in  FIG. 12 , the push plate  126  is inhibited from rotating by pins  150  extending from the main bracket  112 , and is guided thereby in the front-and-rear direction. The push plate  126  moves in the front-and-rear direction with the outer sleeve  124 . When the push plate  126  moves forward, the link  94  of the cutting mechanism  38  of  FIG. 4  is driven, and the cutter  70  cuts the wire W. Thereafter, when the push plate  126  moves backward, the link  94  of the cutting mechanism  38  is driven in an opposite direction, and the cutter  70  is brought to its initial posture. Further, as shown in  FIG. 12 , the push plate  126  is provided with a permanent magnet  152 . The main bracket  112  is provided with a magnetic sensor  154  corresponding to the permanent magnet  152 . The magnetic sensor  154  is connected to the control board  180  by a connection wire (not shown). A signal detected by the magnetic sensor  154  is inputted to the control board  180 . The rebar tying tool  2  can determine whether or not the push plate  126  is in its initial position based on the detection result of the magnetic sensor  154 . 
         [0087]    As shown in  FIG. 15 , the supporting sleeve  130  is a cylindrical member covering a periphery of the outer sleeve  124 . The supporting sleeve  130  is rotatable relative to the outer sleeve  124 , and is movable in the front-and-rear direction. The supporting sleeve  130  is supported by the left outer housing  14  and the inner housing  16  rotatably but immovably in the front-and-rear direction. 
         [0088]    On an outer surface of the outer sleeve  124  on its rear side, short fins  124   a  and long fins  124   b  extending in the font-and-rear direction are provided. The short fins  124   a  and the long fins  124   b  allow or inhibit rotation of the outer sleeve  124  in cooperation with a rotation restricting mechanism  156  (see  FIG. 12 ). In the rebar tying tool  2  of the present embodiment, on the outer surface of the outer sleeve  124 , two long fins  124   b  are disposed at 180 degrees&#39; intervals, and six short fins  124   a  are disposed at 45 degrees&#39; intervals between those two long fins  124   b.    
         [0089]    As shown in  FIG. 18 , the rotation restricting mechanism  156  comprises a base member  158 , an upper arm member  160 , and a lower arm member  162 . The base member  158  is fixed to the inner housing  16 . The upper arm member  160  is pivotaly supported by the base member  158  via a pivot shaft  160   a . The upper arm member  160  comprises a restriction piece  160   b . The upper arm member  160  is biased by a torsion spring  160   c  in a direction along which the restriction piece  160   b  is opened outward. In a case where the screw shaft  120  rotates in a clockwise direction (the twisting mechanism  40  has finished twisting the wire W and returns to its initial posture), the short fins  124   a  and the long fins  124   b  serve topress in the upper arm member  160 , and thus the upper arm member  160  does not inhibit the rotation of the outer sleeve  124 . In a case where the outer sleeve  124  rotates in a counterclockwise direction (the twisting mechanism  40  is griping the wire W and twists it), the short fins  124   a  and the long fins  124   b  come into contact with an end surface of the restriction piece  160   b , and thus the upper arm member  160  inhibits the rotation of the outer sleeve  124 . The lower arm member  162  is pivotaly supported by the base member  158  via a pivot shaft  162   a . The lower arm member  162  comprises a restriction piece  162   b . The lower arm member  162  is biased by a torsion spring  162   c  in a direction along which the restriction piece  162   b  is opened outward. In the case where the outer sleeve  124  rotates in the counterclockwise direction (the twisting mechanism  40  is gripping the wire W and twists it), the short fins  124   a  and the long fins  124   b  serve to press in the lower arm member  162 , and thus the lower arm member  162  does not inhibit the rotation of the outer sleeve  124 . In the case where the outer sleeve  124  rotates in the clockwise direction (the twisting mechanism  40  has finished twisting the wire W and returns to its initial posture), the short fins  124   a  and the long fins  124   b  come into contact with an end surface of the restriction piece  162   b , and thus the lower arm member  162  inhibits the rotation of the outer sleeve  124 . As shown in  FIG. 18 , a rear end of the restriction piece  160   b  of the upper arm member  160  is disposed more rearward than a rear end of the restriction piece  162   b  of the lower arm member  162 . Further, a front end of the restriction piece  162   b  of the lower arm member  162  is disposed more forward than a front end of the restriction piece  160   b  of the upper arm member  160 . 
         [0090]      FIGS. 19 to 22  show an operation of the grip mechanism  102 . As shown in  FIG. 19 , with an initial posture before the twisting motor  96  is driven, most part of the screw shaft  120  is housed within the inner sleeve  122 , and one of the long fins  124   b  of the outer sleeve  124  is held between the upper arm member  160  and the lower arm member  162  of the rotation restricting mechanism  156 . Further, the distal shaft  132  is in a state of having moved forward relative to the outer sleeve  124 , and the right hook  134  and the left hook  136  are in their maximum opened state. 
         [0091]    From this state, when the screw shaft  120  rotates in the counterclockwise direction by being driven by the twisting motor  96 , since the rotation of the outer sleeve  124  is inhibited due to the long fin  124   b  being in contact with the restriction piece  160   b  of the upper arm member  160 , the inner sleeve  122  and the outer sleeve  124  move forward relative to the screw shaft  120  as shown in  FIG. 20 . As the outer sleeve  124  moves forward, the distal shaft  132  also moves forward relative to the screw shaft  120  due to the biasing force of the compression spring  140 . The distal shaft  132  can move forward until the stopper  142  comes into contact with the front end of the engaging groove  120   d.    
         [0092]    From this state, when the screw shaft  120  rotates further in the counterclockwise direction, the outer sleeve  124  further moves forward relative to the screw shaft  120  as shown in  FIG. 21 . However, the distal shaft  132  cannot move forward any further because the stopper  142  is in contact with the front end of the engaging groove  120   d . Due to this, the distal shaft  132  is relatively drawn into the outer sleeve  124 , and the right hook  134  and the left hook  136  move in a closing direction. 
         [0093]    From this state, when the screw shaft  120  rotates yet further in the counterclockwise direction, the outer sleeve  124  further moves forward relative to the screw shaft  120 . As shown in  FIG. 22 , the distal shaft  132  is completely drawn into the outer sleeve  124 , and the right hook  134  and the left hook  136  come to be in a completely closed state. Due to this, the wire W is gripped by the right book  134  and the left hook  136 . 
         [0094]    At a timing shortly before the right hook  134  and the left hook  136  are completely closed, the long fin  124   b  and the upper arm member  160  comes to be no longer in contact in the rotation restricting mechanism  156 . Due to this, after this timing, the outer sleeve  124  rotates accompanying the rotation of the screw shaft  120 , and the right hook  134  and the left hook  136  also rotate. Due to this, the wire W gripped by the right hook  134  and the left hook  136  is twisted. The twisting mechanism  40  rotates the twisting motor  96  in a reverse direction after having twisted the wire W to a certain twisting strength. 
         [0095]    When the twisting motor  96  is rotated in the reverse direction, that is, in the clockwise direction, the screw shaft  120  also rotates in the clockwise direction. At this occasion, when the outer sleeve  124  rotates slightly, one of the short fins  124   a  or one of the long fins  124   b  makes contact with the restriction piece  162   b  of the lower arm member  162 , and the rotation of the outer sleeve  124  is thereby inhibited; thus, the outer sleeve  124  moves backward relative to the screw shaft  120  at almost the same rotational angle at a time when the right book  134  and the left hook  136  finished twisting the wire W. At this occasion, the distal shaft  132  is maintained in the state of having moved forward relative to the screw shaft  120  by the biasing force of the compression spring  140 , and thus the distal shaft  132  is relatively pulled out from the outer sleeve  124 , and the right hook  134  and the left hook  136  start to open. 
         [0096]    Thereafter, when the screw shaft  120  is rotated further in the clockwise direction, the outer sleeve  124  further moves backward relative to the screw shaft  120 , resulting in the distal shaft  132  being completely pulled out from the outer sleeve  124 , and the right hook  134  and the left hook  136  come to be in a completely opened state. After having reached this state, the distal shaft  132  moves backward relative to the screw shaft  120  together with the outer sleeve  124 . 
         [0097]    Thereafter, when the screw shaft  120  is rotated yet further in the clockwise direction, the outer sleeve  124  and the distal shaft  132  further move backward relative to the screw shaft  120 , resulting in the most part of the screw shaft  120  being housed within the inner sleeve  122 . At this occasion, if one of the short fins  124   a  has been in contact with the lower arm member  162  of the rotation restricting mechanism  156 , the short fin  124   a  comes to make no contact with the lower arm member  162 , and the rotation of the outer sleeve  124  is thereby allowed. At this occasion, the compression spring  140  and the bumper  138  are strongly compressed, and strong biasing force is applied from the compression spring  140  and the bumper  138 . As a result of this, large frictional force is applied between the ball groove  120   c  of the screw shaft  120  and the ball  144  fitted in the ball hole of the inner sleeve  122 , thus when the screw shaft  120  rotates, the outer sleeve  124  rotates together with the screw shaft  120  without moving backward relative to the screw shaft  120 . When one of the long fins  124   b  makes contact with the lower arm member  162  of the rotation restricting mechanism  156  due to the rotation of the outer sleeve  124 , the rotation of the outer sleeve  124  is again inhibited, and the outer sleeve  124  further moves backward. When the magnetic sensor  154  detects that the outer sleeve  124  has completely moved backward, the twisting mechanism  40  stops the rotation of the twisting motor  96 . Due to this, the twisting mechanism  40  returns to its initial posture. 
         [0098]    As shown in  FIG. 1 , when the user positions the rebar tying tool  2  such that the plural rebars R are arranged between the upper curl guide  60  and the lower curl guide  62  and pulls the trigger  7 , the rebar tying tool  2  performs the series of operations of winding the wire W around the rebars R by the feeding mechanism  32 , the guide mechanism  34 , and the brake mechanism  36 , and cutting and twisting the wire W wound around the rebars R by the cutting mechanism  38  and the twisting mechanism  40 . 
         [0099]    Hereinbelow, an assembling work of the rebar tying tool  2  will be described with reference to  FIGS. 23 to 27 . Notably, in  FIGS. 23 to 27 , connection wires and the like are not shown for easier view of the drawings. Firstly, as shown in  FIG. 23 , the cover  17  is installed onto the left outer housing  14 . Then, as shown in  FIG. 24 , the trigger  7 , the terminal  9 , the first operation and display unit board  21  and the first switch plate  23  of the first operation and display unit  18 , the second operation and display unit board  25  and the second switch plate  27  of the second operation and display unit  24 , the guide mechanism  34 , the cutting mechanism  38 , the twisting mechanism  40 , the state detection mechanism  78 , the control board  180 , and the like are installed onto the left outer housing  14 . On an inner surface of the left outer housing  14 , that is, on a surface facing the inner housing  16 , a twisting mechanism retaining portion  170  which comprises a twisting motor retaining portion  164  for retaining the twisting motor  96 , a first reduction mechanism retaining portion  166  for retaining the first reduction mechanism  98 , and a supporting sleeve retaining portion  168  for retaining the supporting sleeve  130  is provided, and the twisting mechanism  40  is retained by the twisting mechanism retaining portion  170 . Further, the guide mechanism  34 , the cutting mechanism  38 , and the state detection mechanism  78  are fixed to the left outer housing  14  by screws  182 . At this occasion, wire connecting work for connecting the control board  180  with each of the trigger  7 , the terminal  9 , the first operation and display unit board  21 , the second operation and display unit board  25 , the twisting mechanism  40 , and the state detection mechanism  78  is also performed. Thereafter, as shown in  FIG. 25 , the inner housing  16  is installed onto the left outer housing  14  using screws  184  and small screws  185 . Thereafter, as shown in  FIG. 26 , the accommodating mechanism  30 , the feeding mechanism  32 , and the brake mechanism  36  are respectively installed onto the inner housing  16 . On a surface of the inner housing  16  facing the right outer housing  12 , a feeding mechanism retaining portion  174  which comprises a feeding motor retaining portion  172  for retaining the feeding motor  44  and a brake mechanism retaining portion  178  which comprises a solenoid retaining portion  176  for retaining the solenoid  86  are provided, the feeding mechanism  32  is retained by the feeding mechanism retaining portion  174 , and the brake mechanism  36  is retained by the brake mechanism retaining portion  178 . The accommodating mechanism  30  and the brake mechanism  36  are fixed to the inner housing  16  by the screws  184 . At this occasion, wire connecting work for connecting each of the feeding mechanism  32  and the brake mechanism  36  with the control board  180  is also performed. Thereafter, as shown in  FIG. 27 , the right outer housing  12  is installed onto the left outer housing  14  and the inner housing  16  by screws  186 , thereby the rebar tying tool  2  being assembled completely. As above, upon assembling the rebar tying tool  2 , the respective constituent elements such as the twisting mechanism  40 , the cutting mechanism  38 , the guide mechanism  34 , the feeding mechanism  32 , the brake mechanism  36 , and the like can be installed by work from one side of the rebar tying tool  2  without turning over the rebar tying tool  2 . Therefore, the assembling work can easily be performed. 
         [0100]    In the present embodiment, the control board  180  is disposed so as to extend across the inner housing  16 , the part of the control board  180  is disposed on the one side as seen from the inner housing  16  (right outer housing  12  side), and another part of the control board  180  is disposed on the other side as seen from the inner housing  16  (left outer housing  14  side). Due to this, the wire connection between the feeding motor  44  of the feeding mechanism  32  and the control board  180  as well as the wire connection between the solenoid  86  of the brake mechanism  36  and the control board  180  can be performed in the space on the one side as seen from the inner housing  16  (right outer housing  12  side). Further, the wire connection between the twisting motor  96  of the twisting mechanism  40  and the control board  180  can be performed on the other side as seen from the inner housing  16  (left outer housing  14  side). By configuring as above, holes and connection terminals for passing the connection wires between the control board  180  and each of the feeding motor  44 , the solenoid  86 , and the twisting motor  96  do not need to be provided in the inner housing  16 . Further, since the connection wires do not need to be passed from the one side to the other side of the inner housing  16 , the assembly workability of the rebar tying tool  2  can be improved. Notably, as the control board  180 , a feeding motor control board for controlling the feeding motor  44 , a solenoid control board for controlling the solenoid  86 , and a twisting motor control board for controlling the twisting motor  96  may be provided separately. In this case, if the feeding motor control board, the solenoid control board, and the twisting motor control board are configured so that a part of each of the boards is disposed on the one side as seen from the inner housing  16  (right outer housing  12  side), and another part of each of the boards is disposed on the other side as seen from the inner housing  16  (left outer housing  14  side), effects similar to the aforementioned effects can be achieved. 
         [0101]    While specific examples of the present disclosure have been described above in detail, these examples are merely illustrative and place no limitation on the scope of the patent claims. The technology described in the patent claims also encompasses various changes and modifications to the specific examples described above. The technical elements explained in the present disclosure or drawings provide technical utility either independently or through various combinations. The present disclosure is not limited to the combinations described at the time the claims are filed. Further the purpose of the examples illustrated by the present disclosure or drawings is to satisfy multiple objectives simultaneously, and satisfying any one of those objectives gives technical utility to the present disclosure.