Patent Publication Number: US-9404275-B2

Title: Reinforcing bar wire tying apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO COMPACT DISC(S) 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates, in general, to tools used in construction of reinforced concrete structures, and in particular, to tools for tying together the reinforcing bars (hereinafter, “re-bars”) used within reinforced concrete structures. 
     2. Information Disclosure Statement 
     When constructing structures that employ reinforced concrete, the steel re-bars within the reinforced concrete are typically tied together with binding wires, prior to pouring concrete into the forms, so as to stabilize the position of the re-bars within the reinforced concrete structure during the pouring process, and the ends of the binding wires, after being looped around the re-bars, are typically twisted together so as to retain the binding wire around the re-bars. Because the process of tying re-bars with binding wire is very labor intensive, it is known to use powered mechanical apparatus to do this binding of the re-bars with binding wire, often with the binding wire being continuously fed from a spool and then cut to a desired length, usually prior to twisting the ends of the binding wire. Prior art re-bar tying apparatus are complex with a large number of moving parts that can reduce the reliability of such re-bar tying apparatus. 
     It is therefore desirable to have a powered re-bar wire tying apparatus that quickly and efficiently encircles two or more re-bars with a length of binding wire and then twists the ends of the binding wire to bind the re-bars together. It is further desirable to provide a powered re-bar wire tying apparatus that is simpler than heretofore provided by the prior art. 
     Nishikawa et al., U.S. Pat. No. 4,094,342 (issued Jun. 13, 1978), discloses a pneumatic binder for lacing together a bundle of electrical wires. 
     Furlong et al., U.S. Pat. No. 4,362,192 (issued Dec. 7, 1982), discloses a powered tool having a movable pair of jaws in which the binding wire is fed within loop-forming grooves in the jaws. 
     Kusakari, U.S. Pat. No. 5,279,336 (issued Jan. 18, 1994), discloses a wire binder for binding reinforcing bars in which binding wire is supplied from a spool and a wire-twisting motor twists the ends of the binding wire. 
     Hanagasaki et al., U.S. Pat. No. 5,515,887 (issued May 14, 1996), discloses a wire reel used in a reinforcing bar binding machine. 
     Miyazaki, U.S. Pat. No. 5,558,134 (issued Sep. 24, 1996), discloses a binding wire guide mechanism used in a reinforcing bar tying apparatus, which guides binding wire into a wire loop around reinforcing bars. 
     Murayama et al., U.S. Pat. No. 5,678,613 (issued Oct. 21, 1997), discloses a reinforcing bar binding machine with movable jaws that guide fed wire into a loop shape and then twists the ends of the wire and cuts the wire. 
     Kusakari, U.S. Pat. No. 5,694,983 (issued Dec. 9, 1997), discloses a reinforcing bar tying apparatus that has movable jaws. Wire is fed from the apparatus, curled around the reinforcing bar, twisted, and cut. 
     Ishii, U.S. Pat. No. 5,831,404 (issued Nov. 3, 1998), discloses a method of preventing wire from being twisted off in a reinforcing bar tying apparatus, in which a motor torque is electrically monitored and the twisting operation is ended when the motor torque reaches a peak. 
     Murayama et al., U.S. Pat. No. 5,871,036 (issued Feb. 16, 1999), discloses a reinforcement bar binding apparatus having movable jaws in which wire is fed to a guide that loops the wire around reinforcing bars and twists the wire. 
     Ishii, U.S. Pat. No. 5,874,816 (issued Feb. 23, 1999), discloses a reinforcing bar tying apparatus that feeds wire, loops the wire around reinforcing bars, twists the wire, and cuts the wire, and which stops the twisting when the torque does not increase after a predetermined time from starting the twisting operation. 
     Kusakari, U.S. Pat. No. 5,956,989 (issued Sep. 28, 1999), discloses a wire twisting device for use in a reinforcement bar binding machine. 
     Ishikawa et al., U.S. Pat. No. 6,401,766 (issued Jun. 11, 2002), discloses a reinforcing bar tying apparatus that adjusts to accommodate the diameter of the loop of the binding wire, and has a movable jaw. 
     Ehara, U.S. Pat. No. 6,714,399 (issued Mar. 30, 2004), discloses a method of controlling a solenoid actuator by monitoring the drive current of the solenoid drive. 
     Kusakari et al., U.S. Pat. No. 7,051,650 (issued May 30, 2006), discloses a stranding wire twisting device for a reinforcement bar binding machine, in which a twisting shaft with hooks engages a wire loop of binding wire. 
     Yokochi et al., U.S. Pat. No. 7,140,400 (issued Nov. 28, 2006), discloses a reinforcing bar binding machine with a binding wire feeding mechanism having a drive sheave and a driven sheave with V-grooves therearound. 
     Ishikawa et al., U.S. Pat. No. 7,143,792 (issued Dec. 5, 2006), discloses a reinforcing bar binding machine having spaced jaws and a twisting mechanism that grabs the ends of the binding wire and then moves rearward with the grabbed wire. 
     Ishikawa et al., U.S. Pat. No. 7,255,135 (issued Aug. 14, 2007), discloses a reinforcing bar tying machine with movable jaws and rearward-moving clamp plates that grab the ends of the binding wire. 
     Ishii et al., U.S. Pat. No. 7,275,567 (issued Oct. 2, 2007), discloses a reinforcing bar binding machine that feds binding wire and then clamps the end of the binding wire and pulls back while twisting the wire. 
     Kusakari et al., U.S. Pat. No. 7,353,846 (issued Apr. 8, 2008), discloses a reinforcing bar binding machine with a cooling fan for cooling the twisting motor. 
     Kusakari et al., U.S. Pat. No. 7,398,800 (issued Jul. 15, 2008), discloses a reinforcing bar binding machine that has a warm-up cycle for use in a cold environment. 
     Itagaki, U.S. Pat. No. 7,448,417 (issued Nov. 11, 2008), discloses a reinforcing bar binding machine that allows setting of the number of turns by which the binding wire is twisted. 
     Hattori, U.S. Pat. No. Des. 403,937 (issued Jan. 12, 1999), discloses a reinforcing bar binding machine with a battery pack for powering an electric motor of the binding machine. 
     Kusakari, U.S. Pat. No. Des. 409,476 (issued May 11, 1999), discloses a wire bobbin or spool that can be used by a reinforcing bar binding machine. 
     Hattori, U.S. Pat. No. Des. 481,602 (issued Nov. 4, 2003), discloses a reinforcing bar binding machine having a wire spool and a battery pack for powering an electric motor of the binding machine. 
     Kusakari, U.S. Pat. No. Des. 489,399 (issued May 4, 2004), discloses a wire bobbin or spool that can be used by a reinforcing bar binding machine. 
     Nagaoka et al., U.S. Pat. No. Des. 527,041 (issued Aug. 22, 2006), discloses a wire bobbin or spool that can be used by a reinforcing bar binding machine. 
     Hattori, U.S. Pat. No. Des. 619,437 (issued Jul. 13, 2010), discloses a reinforcing bar binding machine having a wire spool and a battery pack for powering an electric motor of the binding machine. 
     None of these references, either singly or in combination, discloses or suggests the present invention. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is a binding wire twisting apparatus for tying reinforcing bars. A motor, either pneumatic or electric, rotates a shaft upon which a member reciprocates from a first (rearward) position to a second (forward) position, with the member being coupled for mutual rotation with the shaft. The apparatus includes first and second opposed fingers with distal tips that are fixedly spaced apart by a gap, and the first and second fingers respectively have first and second opposed channels adapted for slidingly receiving fed binding wire. A first grip piece having a first opening therethrough with a first gripping surface therearound is mounted for rotation coaxial with the axis of the shaft, and a second grip piece with a second gripping surface is at the forward end of the member. When in the rearward position, the member drives a wire feeding unit that selectively feeds binding wire through the first opening, into the first channel of the first finger, then across the gap, then into the second channel of the second finger and back through the first opening of the first grip piece. When the leading end of the fed wire impacts a target on an actuator of a four-way valve, a pneumatic cylinder is caused to reciprocate the member from the first position to the second position. As the member moves into the second position, a cutter cuts the wire. Once in the second position, the second gripping surface of the second grip piece entraps and holds the ends of the wire to the first gripping surface of the first grip piece, and the rotating member, while holding the ends of the wire between the first and second grip pieces, twists and ties the wire around the reinforcing bars. As the wire becomes tied, the wire is pulled from the channels of the fingers. A torque-release clutch decouples the motor from the shaft when the torque on the tied wire passes an adjusted threshold. 
     It is an object of the present invention to provide a binding wire twisting apparatus for tying reinforcing bars. It is a further object of the present invention to provide a simpler and thus more reliable binding wire twisting apparatus than heretofore known in the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a right side view of a first embodiment of the present invention, showing the tying together of two reinforcing bars. 
         FIG. 2  is a left side view of the first embodiment of the present invention, showing the tying together of two reinforcing bars. 
         FIG. 3  is a perspective view of the wire feeding unit of the present invention. 
         FIG. 4  is a top sectional view of the wire feeding unit of the present invention, taken substantially along the line  4 - 4  shown in  FIG. 3 . 
         FIG. 5  is a perspective view of certain parts of the present invention with other parts removed for clarity. 
         FIG. 5A  is a transverse sectional view showing the mounting of the member on the shaft of the present invention, and showing the first gear of the member, taken substantially along the line  5 A- 5 A shown in  FIG. 5 . 
         FIG. 6  is a top sectional view of a portion of the present invention with some parts removed for clarity, taken substantially along the line  6 - 6  shown in  FIG. 1 , as the leading end of the binding wire is fed through the first opening of the first grip piece. 
         FIG. 7  is a top sectional view of a portion of the present invention with some parts removed for clarity, taken substantially along the line  7 - 7  shown in  FIG. 1 , similar to  FIG. 6  but just after the leading end of the binding wire impacts the target of the control means. 
         FIG. 8  is a top sectional view of a portion of the present invention with some parts removed for clarity, taken substantially along the line  8 - 8  shown in  FIG. 1 , similar to  FIGS. 6 and 7  but showing the twisting of the binding wire. 
         FIG. 9  is a front sectional view of a portion of the present invention, taken substantially along the line  9 - 9  shown in  FIG. 7 . 
         FIG. 10  is a front sectional view of the present invention, taken substantially along the line  10 - 10  shown in  FIG. 7 . 
         FIG. 11  is a schematic diagram of the first embodiment of the present invention, showing the operation of various parts. 
         FIG. 12  is a side view of a second embodiment of the present invention, similar to the side view shown in  FIG. 1  of the first embodiment. 
         FIG. 13  is a schematic diagram of the second embodiment of the present invention, showing the operation of various parts and similar to the schematic diagram of the first embodiment shown in  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-11 , the first embodiment  20  of the binding wire twisting apparatus of the present invention is shown tying a portion  22  of binding wire  30  to well-known reinforcing bars (“re-bars”)  24  and  26 . 
     Apparatus  20  has a body  27  and includes a wire feeding unit  28  for selectively feeding binding wire  30  from a supply  32  of binding wire, and the supply  32  of binding wire may be a well-known spool or bobbin  34  on which the binding wire is wound. Depending on the particular application and sizes of re-bar being tied, differing gauges of binding wire may be chosen, in a manner well-known to those skilled in the art, for use with the present invention. 
     As best seen in  FIGS. 1, 3, and 4 , wire feeding unit  28  preferably includes a first sheave  36  having a first circumferential groove  38  therearound between first and second circumferential sets  40 ,  42  of gear teeth, and a second sheave  44  having a second circumferential groove  46  therearound between third and fourth circumferential sets  48 ,  50  of gear teeth, with the gear teeth of first sheave  36  being engaged with the gear teeth of second sheave  44  so as to operably couple first and second sheaves  36 ,  44  for mutual opposite-direction rotation as first sheave  36  turns upon a first sheave axle  52  and second sheave  44  turns upon a second sheave axle  54 . Grooves  38  and  46  are adapted for frictionally receiving binding wire  30  therebetween so as to feed the binding wire  30  as first and second sheaves  36 ,  44  mutually rotate in opposite directions. An example of such sheaves and their feeding of binding wire is shown in Yokochi et al., U.S. Pat. No. 7,140,400 (issued Nov. 28, 2006), fully incorporated by reference herein. 
     As seen best in  FIGS. 3 and 4 , one of first and second sheaves  36 ,  44  is selectively operably coupled, in a manner hereinafter described in detail, to a member  56  that is coupled for mutual rotation with a rotating shaft  58  of apparatus  20  in a manner hereinafter described in detail. Member  56  preferably has a first gear  60  that, when member  56  is in a first position  62  shown in  FIG. 4 , engages with a second gear  64  of one of first and second sheaves  36 ,  44 , preferably such as second gear  64  fixedly mounted with second sheave  44  upon second sheave axle  54 , operably couples member  56  to second sheave  44  so that rotation of member  56  with shaft  58  drives second sheave  44  to rotate, and second sheave  44 , by the engagement of third and fourth circumferential sets  48 ,  50  of gear teeth with first and second circumferential sets of gear teeth  40 ,  42 , causes first sheave  36  to be driven to rotate as well, thereby feeding binding wire  30  in a manner that is now understood. 
     Member  56  is coupled for mutual rotation with rotating shaft  58  as by shaft  58  being splined, keyed, or preferably having a hexagonal shape in transverse cross section as shown in  FIG. 5A , with member  56  having an axial bore therethrough adapted for sliding mating engagement with shaft  58  so as to permit member  56  to slidingly reciprocate upon shaft  58  and with respect to shaft  58 . 
     As wire  30  emerges from the wire feeding unit  28 , it enters a guide tube  66  that directs wire  30  toward and through a first opening  68  of a first grip piece  70 , hereinafter described in detail. As wire  30  emerges from guide tube  66 , it passes through the scissor-like jaws  72 ,  74  of a cutter  76  that is engaged to cut wire  30  as member  56  reciprocates upon shaft  58 , and with respect to shaft  58 , from first position  62  into a second position  78  as shown in  FIG. 8 , with  FIG. 7  showing member  56  approaching and almost but not yet fully into second position  78 . 
     Shaft  58  has a longitudinal axis of rotation  80  and is rotated about that axis by a motor  82 . In the first preferred embodiment  20 , motor  82  is a pneumatic motor having a well-known adjustable torque-release clutch  84  interposed between the output shaft of motor  82  and shaft  58 , and torque-release clutch  84  decouples the shaft  86  of motor  82  from shaft  58  such that clutch  84  becomes disengaged when the rotation of shaft  58  by motor  82  is opposed as the torque resistance encountered upon twisting the binding wire increases past a predetermined desired torque threshold, and that torque resistance depends on the size of binding wire being used and how tight of a twisted tie is desired. If the torque threshold is set too low by the user of the present invention, the tie will not be twisted tightly enough. If the torque threshold is set too high, the tie will be twisted too tightly and the binding wire will break rather than hold the re-bar together. 
     A suitable pneumatic motor  82  with torque-release clutch  84  for use with the present invention is the well-known type used in the model R55BBP pneumatic air screwdriver with torque release clutch sold by Mijy-Land Industrial Co., Ltd., 21, Lane 323, Fuh Hsing Rd. Lujhou City, Taipei, Hsien, Taiwan 247, which has a nominal free-running speed of 1000 RPM and an adjustable torque-release range of 12 to 75 Kgf-cm (about 1.2 Newton-meters to 7.4 Newton-meters). 
     Pneumatic motor  82  is powered from a well-known source  88  of pressurized air, such as a well-known compressor, with a pressurized air hose  90  connecting motor  82  to pressurized air source  88 . Interposed between air source  88  and motor  82  is a well-known valve  92  that is operated by a spring-loaded trigger  94  to selectively apply pressurized air to motor  82  such that, when trigger  94  is depressed (shown in solid outline in  FIGS. 1 and 2 ), valve  92  opens and allows pressurized air from source  88  to cause motor  82  to turn its shaft  86  and operate apparatus  20 . When trigger  94  is released (shown in dotted outline in  FIGS. 1 and 2 ), valve  92  closes, thereby removing the pressurized air from motor  82  and ceasing the turning of shaft  86 . 
     As best seen in  FIGS. 1, 2, 6, 7, and 8 , apparatus  20  includes first and second opposed fingers  96 ,  98  respectively having first and second distal tips  100 ,  102 . Distal tips  100  and  102  are fixedly spaced apart from each other by a gap  104 , with gap  104  being large enough to permit passage of re-bars  24 ,  26  therethrough so as to allow fingers  96 ,  98  to encircle re-bars  24 ,  26  for tying. In contrast to prior art re-bar tying devices, which had complicated mechanisms for opening and closing of fingers around re-bars, the present invention&#39;s simpler structure produces an improved re-bar tying tool. First and second opposed fingers  96 ,  98  have first and second opposed channels  106 ,  108  therein adapted for slidingly receiving binding wire  30  therewithin as a leading end  110  of binding wire is fed, by wire feeding unit  28  and out of guide tube  66 , through first opening  68  of first grip piece  70 , into the first channel  106  of first finger  96 , then across gap  104 , then into second channel  108  of second finger  98 , and then back through first opening  68  of first grip piece  70 , as best seen in  FIGS. 6 and 7 . First opposed finger  96  is preferably a three-layer sandwich construction of metal pieces  112 ,  114 ,  116  forming channel  106 , and, likewise, second opposed finger  98  is preferably a three-layer sandwich construction of metal pieces  118 ,  120 ,  122  forming channel  108 , with the sandwiched pieces of each finger preferably being riveted or screwed together in a manner well-known to those skilled in the art. The distal entrance  124  to second channel  108  is preferably enlarged, as by respective upward and downward flaring of pieces  118  and  122  (best seen in  FIG. 10 ) so as to form an enlarged mouth to capture the leading end  110  of wire  30  as it passes from first channel  106  across gap  104  into second channel  108 . 
     To selectively and entrapingly retain wire  30  within channel  106 , apparatus  20  preferably has a vertically-reciprocating retaining pin  126 , seen best in  FIGS. 6 and 9 , that reciprocates up and down within a bore  128  in block  130  affixed to the body of apparatus  20 , with block  130  having a forward-facing slot  132 , with slot  132  being in alignment with channel  106 . While member  56  is in its first (rearward) position  62 , pin  126  spans slot  132  so as to guide and retain wire  30  into and within channel  106 . As member  56  moves into its second (forward) position  78 , as hereinafter explained, arm  134 , pivotally mounted to the body of apparatus  20  as at pivot  135  and coupled to pin  126 , is caused to raise pin  126  so as to no longer entrap wire  30  in slot  132  of block  130  (compare the solid outline position of arm  134  with the dotted outline position of arm  134  in  FIGS. 1, 2, and 9 ), thereby allowing wire  30  to be pulled out of channels  106 ,  108  as the wire becomes twisted around the re-bar by apparatus  20 , in a manner hereinafter described in detail. As best seen in  FIGS. 1 and 11 , a spring  133  extends from a rivet or bolt  131 , attached to arm  134 , to a rod  137  mounted transversely within body  27  so as to exert a force that tends to pull arm  134 , when raised as shown in dotted outline in  FIGS. 1 and 11 , back to its unraised position shown in solid outline in  FIGS. 1 and 11 , in a manner hereinafter described in detail. 
     Apparatus  20  further includes reciprocating means  136 , operably coupled to member  56 , for reciprocating member  56  from its first (rearward) position  62  to its second (forward) position  78 . Reciprocating means  136  preferably includes a well-known pneumatic cylinder  138 , connected to pressurized air source  88  as through an air hose  140 . Apparatus  20  further includes control means  142  for selectively causing reciprocating means  136  to reciprocate member  56  from first (rearward) position  62  to second (forward) position  78  and back. Preferably, control means  142  includes a well-known four-way valve  144 , interposed between pneumatic cylinder  138  and air source  88 , that is connected to the forward and rearward ports  146 ,  148  of pneumatic cylinder  138  as by air hoses  150  and  152 , respectively. The actuator  154  of four-way valve  144  includes a target or cup  156  at the distal end of actuator  154  for being impacted by the leading end  110  of the fed binding wire  30 . As the leading end  110  of wire  30  contacts and impacts target  156 , it causes actuator  154  of four-way valve to move from an extended position, shown in solid outline in  FIGS. 5, 6, and 11  and in dotted outline in  FIG. 7 , to a refracted position, shown in dotted outline in  FIGS. 5 and 11  and in solid outline in  FIGS. 7 and 8 . When actuator  154  is in its extended position, the forward port  146  of pneumatic cylinder  138  is supplied pressurized air from air source  88  by valve  144  through hose  150 , and rearward port  148  is vented, thereby causing the rod  158  of pneumatic cylinder  138  to retract. When actuator  154  is in its retracted position, the rearward port  148  of pneumatic cylinder  138  is supplied pressurized air from air source  88  by valve  144  through hose  152 , and forward port  146  is vented, thereby causing the rod  158  of pneumatic cylinder  138  to extend. 
     The distal end of rod  158  is operably coupled to member  56  as through coupling piece  160  of reciprocating means  136 , and coupling piece  160  is mounted for forward and rearward reciprocation within the body of apparatus  20 . The upper edge  162  of coupling piece  160 , as it reciprocates forward, engages with arm  134  to lift pin  126  and thereby no longer entrap wire  30  within block  130 . Furthermore, as coupling piece  160  reciprocates forward and thereby causes member  56  to reciprocate into second position  78 , and before member  56  reaches the second position  78 , coupling piece  160  actuates cutter  76  to cut the wire  30  as best seen in  FIG. 7 . 
     Apparatus  20  further includes a first grip piece  70  having a first opening  68  therethrough, and first opening  68  is coaxial with the axis  80  of rotation of shaft  58 . First opening  68  has a first gripping surface  164  therearound that is teethed as shown for gripping the ends of the wire  30  during twisting, and first grip piece  70  is mounted within the body  27  of apparatus  20  for coaxial rotation about axis  80 , as by having an included bearing  166  that is pressed into body  27 . The forward end of member  56  includes a second grip piece  168  having a second teethed gripping surface  170  adapted for grippingly entrapping the ends of the fed binding wire  30  between second gripping surface  170  and first gripping surface  164  with mutual rotation of the first and second gripping pieces  70 ,  168  when member  56  is in the second (forward) position  78 . 
     Furthermore, for initializing actuator  154  into its extended position, a mechanical linkage  172  is coupled to trigger  94  so that, when trigger  94  is released, a forward end  174  of linkage  172  engagingly pushes (see dotted outline position  176  in  FIG. 6 ) actuator  154  into its extended position, thereby causing pneumatic cylinder  138  to retract its rod  158 , thereby moving member  56  into its first (rearward) position  62 . 
     Now that the parts of apparatus  20  have been described, the use and operation of apparatus  20  can now be explained. 
     Apparatus  20  is first connected to pressurized air source  88  as by hose  90  and trigger  94  is released, thereby causing motor  82  to stop spinning and causing linkage  172  to ensure that actuator  154  of four-way valve  144  is in its extended position, thereby causing pneumatic cylinder  138  to retract rod  158 , thereby causing pin  126  to drop into block  130  and causing member  56  to retract into the first (rearward) position  62 . While member  56  is in first position  62 , first gear  60  of member  56  engages second gear  64  of second sheave  44 . However, because motor  82  is not spinning, wire feeding unit  28  does not feed wire  30  from spool  34 . A pair of reinforcing bars  24 ,  26  are passed through gap  104  so as to be between first and second fingers  96 ,  98 . 
     When trigger  94  is pressed, pressurized air is then caused to flow to motor  82 , causing motor  82  to rotate its shaft  86 , thereby causing shaft  58  to rotate, thereby also causing member  56  to rotate, thereby placing wire feeding unit  28  into its first feeding mode, in which wire feeding unit, by the rotation of first and second sheaves  36 ,  44 , feeds binding wire  30  through guide tube  66 . At the same time, the pressing of trigger  94  retracts the forward end  174  of linkage  172  from actuator  154  of four-way valve  144 , and actuator  154  remains undisturbed in its extended position, held in place by friction within four-way valve  144 , which causes the rod  158  of pneumatic cylinder  138  to remain in its retracted position, thereby keeping member  56  in its first (rearward) position  62 . 
     As best seen in  FIGS. 6 and 7 , the leading end  110  of wire  30  then is fed through the first opening  68  of first grip piece  70 , past rod  126 , and into first channel  106  of first finger  96 . As the leading end  110  of wire  30  reaches the distal end of first channel  106 , it strikes pin  178  at the end of first channel  106  and is directed across gap  104  to the flared distal entrance  124  to second channel  108 . Upon entering second channel  108 , the leading end  110  of wire  30  proceeds along second channel  108  and then back through first opening  68  of first grip piece  70 . After passing through first opening  68  of first grip piece  70 , the leading end  110  of wire  30  continues to be fed until it strikes target  156  of actuator  154 , thereby causing actuator  154  of four-way valve  144  to retract, thereby causing four-way valve  144  to vent the forward port  146  of pneumatic cylinder  138  and to supply pressurized air to the rearward port  148  of pneumatic cylinder  138 , thereby causing rod  158  to extend. 
     As rod  158  extends, coupling piece  160  is caused to reciprocate forward, which reciprocatingly moves member  56 , still turning, out of first (rearward) position  62  and toward second (forward) position  78 . As member  56  moves out of its first position  62 , first gear  60  of member  56  disengages from second gear  64  of second sheave  44 , causing wire feeding unit  28  to enter its second feeding mode, in which it does not feed the wire  30 . As coupling piece  160  is caused to reciprocate forward, upper edge  162  of coupling piece  160  engages arm  134 , causing arm  134  to pivot upwardly about pivot  135 , thereby raising pin  126  within bore  128  of block  130 . As coupling piece  160  continues to reciprocate forward, and before member  56  fully reaches its second (forward) position  78 , cutter  76  is actuated, and scissor jaws  72 ,  74  of cutter  76  cut wire  30 , leaving a cut portion  22  of wire  30  within first and second channels  106 ,  108  of first and second fingers  96 ,  98  and encircling the reinforcing bars  24 ,  26 , with portion  22  of wire  30  having both of its ends passing through the first opening  68  of first grip piece  70  as best seen in  FIG. 7 . 
     As coupling piece  160  continues to reciprocate forward, member  56  fully reaches its second (forward) position  78  shown in  FIG. 8 , and second gripping surface  170  of second grip piece  168  grippingly entraps the ends of the portion  22  of fed binding wire  30  between second gripping surface  170  and first gripping surface  164  of first grip piece  70 . Motor  82 , still rotating, continues to rotate shaft  58  and member  56  about axis  80 , thereby twisting the entrapped ends of portion  22  of wire  30  as seen in  FIG. 8 . It shall be understood that, as the ends of portion  22  of wire  30  become twisted, the leading end  110  of wire  30  will pull away from target  156  of actuator  154 , but actuator  154  will remain in its extended position due to friction within four-way valve  144 . Also, as the ends of portion  22  of wire  30  become twisted and tighten about reinforcing bars  24 ,  26 , portion  22  of wire  30  will be drawn around reinforcing bars  24 ,  26  and out of first and second channels  106 ,  108  of first and second fingers  96 ,  98 . Eventually, the torque seen by torque-release clutch  84  will reach its pre-adjusted threshold, causing motor  82  to become decoupled from shaft  58 , causing the mutual rotation of shaft  58  and member  56  to cease even though trigger  94  may remain depressed, thereby preventing the breaking of wire portion  22 . 
     The operator of apparatus  20  will hear the change in pitch of motor  82  as torque-release clutch  84  disengages, and will then release trigger  94 , causing valve  92  to no longer supply pressurized air to motor  82 , thereby causing motor  82  to stop spinning When trigger  94  is released, the forward end  174  of linkage  172  will again engage actuator  154  of four-way valve  144  and cause actuator  154  to move to its extended position, thereby causing four-way valve to vent the rearward port  148  of pneumatic cylinder  138  and to supply pressurized air to the forward port  146  of pneumatic cylinder  138 , thereby causing pneumatic cylinder  138  to retract rod  158 , thereby causing coupling piece  160  to reciprocate rearwardly, thereby allowing spring  133  to pull arm  134  back to its unraised position (shown in solid outline in  FIGS. 1 and 11 ), thereby causing pin  126  to drop and member  56 , now no longer rotating because motor  82  has ceased being powered, to move from its second (forward) position  78  back to its first (rearward) position  62 . As member  56  moves out of its second (forward) position  78 , second grip piece  168  releases the ends of the twisted wire, and the apparatus  20  can be removed from reinforcing bars  24 ,  26 , as they are withdrawn through gap  104 . 
     A second preferred embodiment  2 . 20  of the present invention is shown in  FIGS. 12 and 13 .  FIG. 12  is a side view of the second embodiment, similar to the side view shown in  FIG. 1  of the first embodiment.  FIG. 13  is a schematic diagram of the second embodiment, showing the operation of various parts and similar to the schematic diagram of the first embodiment shown in  FIG. 11 . Identifying reference designators for this second embodiment are marked similarly to the first embodiment, except with the prefix “2.”. It shall be understood that many aspects of the two embodiments are substantially the same, and only the differences will be treated in detail, it being understood that similar structural features of the two embodiments perform similar functions. 
     The second embodiment  2 . 20 , rather than having a pneumatic motor  82  as in the first embodiment, instead has an electric motor  2 . 82  of similar torque and RPM ratings as the pneumatic motor  82  of the first embodiment. Electric motor  2 . 82 , rather than being powered from pressurized air source  88 , instead is powered by a well-known rechargeable battery module  2 . 89 . Trigger  94 , rather than opening and closing a valve  92  to selectively power the motor  82  by pressurized air as in the first embodiment, instead operates a switch  2 . 92  to selectively power the electric motor  2 . 82 . Electric motor  2 . 82  preferably includes a reduction gear drive  180  to reduce the relatively high armature rotational speed of motor  2 . 82  to a similar RPM as seen with pneumatic motor  82  of the first embodiment, with accompanying increase in output torque, in a manner well-known to those skilled in the art. As with the pneumatic motor  82  of the first embodiment, a torque-release clutch  2 . 84  is interposed between the output shaft of motor  2 . 82  and shaft  58 , and decouples the output shaft of reduction gear drive  180  from shaft  58  when the torque resistance encountered upon twisting the binding wire increases past a desired threshold, and that torque resistance depends on the size of binding wire being used and how tight of a twisted tie is desired. 
     Second embodiment  2 . 20  also has a small bottle of pressurized air  2 . 88  that is preferably mounted on the worker&#39;s belt B so as to operate the four-way valve  144  of control means  142 . It shall be understood that the amount of pressurized air required to operate the pneumatic cylinder  138  of the reciprocating means is much smaller than the amount of pressurized air required to operate the motor  82  of the first embodiment, so a relatively small bottle of pressurized air suffices to power the pneumatic cylinder  138 . By these differences from the first embodiment, the second embodiment is no longer tethered by a supply hose  90  to a large pressurized air source  88  as is the first embodiment, enabling the second embodiment  2 . 20  to be used to tie re-bar where such tethering is not possible or practical. 
     The use and operation of second embodiment  2 . 20  is the same as for the first embodiment  20 , hereinbefore described. 
     It should be understood that both “long” and “short” versions of first and second opposed fingers  96 ,  98  are preferably provided with either the first or second embodiments  20 ,  2 . 20  of the present invention, with a “long” version being as shown in the drawing figures for use with larger sizes of re-bars  24 ,  26  and having a larger gap  104  for passage of the larger re-bars therethrough. Likewise, to avoid wasting binding wire when smaller re-bars are being tied, a “short” version of first and second opposed fingers  96 ,  98  is also preferably provided, having a correspondingly smaller gap  104 , for replacement of the “long” version of first and second opposed fingers  96 ,  98  in those situations when smaller sizes of re-bars are being tied, it being understood that, with smaller re-bars, the encircling fingers  96 ,  98  can be smaller (and shorter) so as encircle the smaller re-bars without excessive gap between fingers  96 ,  98 . While a larger size of first and second opposed fingers  96 ,  98  would still work with smaller re-bars, the longer length of channels  106 ,  108  and longer gap  104  of longer fingers  96 ,  98  would cause the length of wire portion  22  to be greater than required to tie the smaller re-bars, thereby wasting wire. In normal usage, all of the re-bars on a given job will be of the same size, so changing of the fingers  96 ,  98  from “long” to “short” versions would not usually be required while working on a given job. 
     INDUSTRIAL APPLICABILITY 
     Both embodiments of the present invention provide for binding reinforcing bars together with binding wire so as to stabilize the reinforcing bars during the poring of concrete when building structures of reinforced concrete. 
     Although the present invention has been described and illustrated with respect to a preferred embodiment and a preferred use therefor, it is not to be so limited since modifications and changes can be made therein which are within the full intended scope of the invention.