Abstract:
A bar connecting apparatus applies clips to connect transverse bars used in reinforced concrete. A clip string is fed into the bar connecting apparatus by a clip feed assembly, so several pairs of transverse bars can be connected in rapid succession. A hammer reciprocates in the barrel of the bar connecting apparatus, and drives a clip from the barrel into engagement with the bars. An alignment head aligns the bar connecting apparatus with the transverse bars so the clips properly engage the bars.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a Non-Provisional Utility application which claims benefit of co-pending U.S. Provisional Patent Application Ser. No. 60/860,434 filed Nov. 21, 2006, entitled “CLIP APPLYING APPARATUS” which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method for attaching clips to connect bars, wherein the bars are used to reinforce concrete. Reinforcing bars are commonly placed within a frame where cement is to be poured, so that the reinforcing bars will become encased in the poured cement. The reinforcing bars are placed in specified positions at specified heights within the frame, so the resulting concrete is strengthened. One method used to connect the reinforcing bars before the cement is poured is clips. These clips are attached at the intersection of two bars, so the bars are held together in a fixed position. The current invention provides an apparatus and a method for attaching clips to intersecting bars. 
     2. Description of the Related Art 
     Supporting bars are commonly used to reinforce concrete. The supporting bars are laid out in a grid where the cement is to be poured. To maximize the effectiveness of the supporting bars, they are placed at specified heights, usually between about 2 and 6 inches from the ground. The bars are then connected so the grid is stable and will not move when the concrete is poured. 
     Many methods have been used to connect the bars, and many are done by hand. Rebar is the type of supporting bar most commonly used. When the rebar is connected by hand, it requires a laborer to bend over and connect the rebar at many points within the grid. This is labor intensive, slow, and tends to cause injuries from the repeated bending. In some instances, the rebar grid can be prepared first, and then placed into a form where the concrete will be poured. This can reduce the bending required, but does not address the time and labor needed to connect the rebar. To reduce the time needed to connect rebar and to minimize the time a laborer is working in a stooped over position, several applicators for connecting the rebar have been developed. 
     For example, in U.S. Pat. No. 5,881,452 Nowell et al. describes an apparatus for applying deformable metal fastener clips to concrete reinforcement steel. The Nowell device is a hand held applicator. It applies generally U-shaped deformable metal clips at the intersection of pieces of reinforcing rebar or wire mesh sheets. The apparatus is used to place the U-shaped metal clip around adjacent metal bars and then deform and close the U, thus connecting the bars. 
     West, in U.S. Pat. No. 5,826,629, describes a pneumatic wire tying apparatus for tying crossed reinforcing bars together. This device has a guide member which opens to receive intersecting bars, and then closes onto the bars. In the closed position a length of wire is guided around the bars. A feed mechanism feeds a wire to the guide member, and a twist member engages and twists the wire around the reinforcing bars. 
     BRIEF SUMMARY OF THE INVENTION 
     The current invention relates to an apparatus for applying clips to connect reinforcing bar as is typically used in concrete structures. The bar connecting apparatus as described is designed to fasten plastic clips as defined in U.S. patent application publication number 2006-0248844 A1, which is incorporated herein by reference. The clips are inserted into a barrel, and the apparatus is positioned over transverse supporting bars. A hammer reciprocates longitudinally within the barrel and strikes the clip. The hammer propels the clip out of the distal end of the barrel, which is positioned over the transverse bars, such that the clip engages and connects the bars. An alignment head at the distal end of the barrel is utilized to position the bar connecting apparatus relative to the transverse bars. 
     The clips are provided in a clip string, which is a plurality of clips connected together. In one embodiment, the clips are connected directly to each other, and in another embodiment the clips are connected to a common feed rod. The clip string is inserted into a clip feed assembly, which directs a clip into a clip receiving cavity in the barrel each time the hammer reciprocates. The clip feed assembly engages the hammer through a cam guide, so the motion of the hammer as it reciprocates provides the drive to cycle the clip feed assembly. Therefore, each time the hammer propels a clip from the barrel, the clip feed assembly inserts another clip from the clip string into the barrel, so the bar connecting apparatus can connect several pairs of transverse bars in rapid succession. 
     The clip feed assembly utilizes at least one finger to engage and advance the clip string into the clip receiving cavity. The finger has a pivot point and a sloped side so the finger can ratchet backwards along the clip string before engaging and urging the clip string forward into the clip receiving cavity. The backwards ratcheting motion and forward engaging motion allows the finger to advance clips into the clip receiving cavity as the clip feed assembly reciprocates laterally with each cycle of the hammer. 
     The clip feed assembly includes a clip track, which supports the clip string outside of the clip receiving cavity. In one embodiment, the clip track engages the clip from the top, and the clip track extends through the clip receiving cavity. The hammer has an indentation with legs, so the clip track is received in the indentation with the hammer legs passing beside the clip track. The legs contact and drive the clip from the barrel. In a second embodiment, the clip track terminates before entering the clip receiving cavity, and a resilient retainer is utilized to hold the clip in place until it is driven from the bar connecting apparatus. 
     The hammer is reciprocated by a drive, which can be powered by many sources, including manual and pneumatic sources. The power source first biases the drive and the connected hammer distally to drive a clip from the barrel. Next, the drive and hammer are biased proximally to reposition the hammer for the next clip, and to complete the associated cycling of the clip feed assembly. A handle and a biasing spring are used for the manual embodiment, and a trigger is used to actuate a pneumatic or other power source. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of the clip string. 
         FIG. 2  is a perspective view of a single clip engaged with transverse bars. 
         FIG. 3  is a perspective view of the clip string when the feed rod is utilized. 
         FIG. 4  is a perspective view of the clip string with teeth on the feed rod. 
         FIG. 5  is a side view of the manually driven embodiment of the bar connecting apparatus. 
         FIG. 6  is a side view of a distal portion of the bar connecting apparatus without the clip feed assembly. 
         FIG. 7  is a front view of a distal portion of the bar connecting apparatus without the clip feed assembly. 
         FIG. 8  is a side view of the manual drive portion of the bar connecting apparatus with an attached hammer. 
         FIG. 9  is a side view of the pneumatically driven embodiment of the bar connecting apparatus. 
         FIG. 10  is a side view of a distal portion of the bar connecting apparatus. 
         FIG. 11  is a top view of a finger of the clip feed assembly. 
         FIG. 12  is a top view of a clip string engaged by fingers of the clip feed assembly. 
         FIG. 13  is a side view of the hammer having an indentation. 
         FIG. 14  is a front view of a portion of the clip receiving cavity with resilient retainers. 
         FIG. 15  is a side view illustrating an alternate design for the cam plate. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Clip String 
     The Bar Connecting Apparatus utilizes a clip string  02  as depicted in  FIG. 1 . The clip string  02  is comprised of a plurality of connected individual clips  04 , wherein the last clip in the series is the terminal clip  06 . In the preferred embodiment, the clips  04  are comprised of plastic and each clip  04  has several components. Referring to  FIG. 2 , the seat  08  is adapted to engage and position a first bar  09 . Below the seat  08  are a plurality of hooks  10 , preferentially four hooks  10  per clip  04 , which are adapted to engage and position a second bar  11  transverse to the first bar  09 . The first bar  09  is also positioned on top of the second bar  11 . The hooks  10  are joined by a joining portion  12 , and each hook  10  has an upper body  14 . 
     The upper body  14  combined with the upper portion of the joining portion  12  defines a cradle  15  for engaging and positioning another bar parallel to and above the second bar  11 . The clip  04  can position a bar parallel to the second bar  11  in the cradle  15 , or it can position a first bar  09  in the seat  08 , but not both at the same time because the seat  08  and the cradle  15  receive bars in areas which interfere with each other. 
     Each clip  04  in the clip string  02  is connected to at least one adjoining clip  04  at the connection point  16 , as seen in  FIG. 1 . The connection point  16  can be defined anywhere on the portion of a clip that abuts an adjoining clip  04 , as long as the clips  04  are connected together. Each clip  04  has at least one connection point  16 , but multiple connection points  16  can be utilized if necessary. The clips  04  are connected such that every clip  04  in the clip string  02  has a consistent orientation. Preferably, the orientation is such that if a bar were received in the hooks  10  of the terminal clip  06 , the same bar could be simultaneously received in the hooks  10  of every other clip  04  in the clip string  02 . Therefore, there would be one axis defined by the hooks  10  of all of the clips  04  in a clip string  02 . Similarly, the cradles  15  defined by the upper bodies  14  of the clips  04  would also be aligned on a single axis. 
     In an alternative embodiment, the clips  04  as defined above are connected to a feed rod  18 , as depicted in  FIG. 3 . If the feed rod  18  is utilized, the connection point  16 B connects each clip  04  to the feed rod  18 . The feed rod  18  can be positioned anywhere along the side of the clip string  02 B as long as the clips  04  are held in a consistent orientation as described above. It is possible for the feed rod  18  to have teeth  19  for advancing the clip string  02 B, as shown in  FIG. 4 . Also, if the feed rod  18  is utilized, each individual clip  04  does not necessarily touch or directly contact the neighboring clip  04 . The clips  04  are connected to the feed rod  18 , and not to each other, so the clips  04  are not held in direct contact with other clips  04  in the clip string  02 B. 
     Every clip string  02 B has only one sized clip  04 , but every clip string  02 B does not necessarily have the same sized clip  04 . The clips  04  are sized to connect a certain size of reinforcing bar, and because there are several sizes of reinforcing bars, there are several sizes of clips  04 . Although the size of a clip  04  in different clip strings  02 B would vary, the feed rod  18  allows the spacing between neighboring clips  04  to be constant. That is, the distance from the front of a larger clip  04  to the front of a neighboring larger clip  04  in one clip string  02 B would be the same as the distance from the front of a smaller clip  04  to the front of a neighboring smaller clip  04  in another clip string  02 B. When a feed rod  18  is utilized, this consistent spacing is possible because the clips  04  do not have to touch to be connected together. The consistent spacing is desirable because it allows for a bar connecting apparatus to apply clips  04  of different sizes without having to adjust or change the clip feed mechanism. 
     Bar Connecting Apparatus 
     The clip string  02  is utilized in the bar connecting apparatus  20  as shown in  FIG. 5 . Inside the bar connecting apparatus  20  is a barrel  22  with a clip receiving cavity  24 . The terminal clip  06  of the clip string  02  is received into the clip receiving cavity  24  of the barrel  22 , which can be seen more clearly in  FIG. 6 .  FIG. 6  does not include the clip feeding mechanism, to more clearly show the barrel  22  with the clip receiving cavity  24 . The clip receiving cavity  24  includes a hole in the side of the barrel  22  which is adapted to receive clips  04  from the clip string  02 . Inside the barrel  22  is a hammer  26  which reciprocates longitudinally within the barrel  22 . As the hammer  26  reciprocates distally, it contacts the terminal clip  06  and expels the terminal clip  06  out the distal end of the barrel  23 . 
     There is an alignment head  28  defined at the distal end of the barrel  23 , which aligns the clip applying apparatus  20  with the bars to be connected. When the terminal clip  06  is ejected from the barrel  22 , the alignment head  28  ensures the bar connecting apparatus  20  is properly aligned with the bars such that the terminal clip  06  connects the bars. After the terminal clip  06  is ejected the hammer  26  reciprocates proximally, the next clip  04  in the clip string  02  is advanced into the clip receiving cavity  24  and becomes the new terminal clip  06 , and the clip applying process is ready to be repeated. 
     The alignment head  28  has two pair of notches  30 ,  30 B adapted to engage transverse bars, as seen in  FIGS. 6 and 7 . For the sake of clarity,  FIG. 7  also does not show the clip feeding mechanism. One pair of notches  30  is deeper than the other pair  30 B, so the first bar  09 , which is on top, is engaged in the deeper pair of notches  30  and the second bar  11 , which is underneath the first bar  09 , is engaged in the more shallow pair of notches  30 B. The notches  30 ,  30 B in each pair are on opposite sides of the alignment head  28 , so the four points of contact between the notches  30 ,  30 B and the transverse bars  09 ,  11  prevent the bar connecting apparatus  20  from moving. The alignment head  28 , when engaged with the transverse bars, fixes the position of the bar connecting apparatus  20  in three dimensions. 
     The hammer  26  is reciprocated by a drive  32 , as seen in  FIGS. 5 and 8 .  FIG. 8  depicts the hammer  26  and the manual drive  32 , without the remainder of the bar connecting apparatus  20 . The drive  32  includes a drive rod  33  which is actuated either manual or automatically. The act of connecting the drive rod  33  to the hammer  26  can be aided by wrench flats in the drive rod  33 . In the manual embodiment, the drive  32  includes a handle  34  and a biasing spring  36 . The handle  34  is manually depressed to extend the hammer  26  distally for ejecting the terminal clip  06  from the barrel  22 . The biasing spring  36  then biases the handle  34  proximally and retracts the hammer  26  to a position such that the next terminal clip  06  can be introduced into the clip receiving cavity  24 . 
       FIG. 9  depicts the bar connecting apparatus  20 A with a trigger actuated automatic drive  32 A. For the sake of clarity, similar components in the manual and automatic embodiments are given the same name and number, but the component numbers in the automatic embodiment are designated with an “A.” The drive  32 A includes a trigger  38  for directing a power source to cycle the drive  32 A, such that the power source biases the drive  32 A distally when the trigger  38  is depressed and proximally when the trigger  38  is released. In the preferred embodiment, the power source is pneumatic; however, other power sources, such as an electric power source, could also be utilized. Additionally, an extension can be added to either the automatic or manual drive  32 ,  32 A so an operator can stand upright while connecting bars. 
     Clip Feed Assembly 
     The clip feed assembly  40  advances the clip string  02  into the clip receiving cavity  24  as the hammer  26  reciprocates, as seen in  FIG. 10 . A cam guide  42  is connected to the side of the hammer  26 . The cam guide  42  passes through a straight slot and protrudes from the side of the barrel  22 . Therefore, the cam guide  42  reciprocates outside of the barrel  22  as the hammer  26  reciprocates inside of the barrel  22 . The cam guide  42  can include a bearing to make the motion of the cam guide  42  smoother. 
     The portion of the cam guide  42  which protrudes from the side of the barrel  22  is engaged in a slot type cam track  44 . The cam track  44  is defined in the cam plate  46 , and the cam plate  46  is pivotally connected to the bar connecting apparatus  20  at a pivot point  48 . The cam track  44  has an angled section such that as the hammer  26  and cam guide  42  cycle, the cam plate  46  pivots at the pivot point  48  and reciprocates laterally. The cam track  44  can also include straight sections, which are used for timing purposes to coordinate the clip feed assembly operation  40  with the cycling of the hammer  26 . The cam plate  46  reciprocates away from the barrel  22  as the hammer  26  reciprocates distally, and the cam plate  46  reciprocates towards the barrel  22  as the hammer  26  reciprocates proximally. With the slot type cam track  44  no return spring is needed for cam plate  46 . 
     An alternate design for the cam plate, designated as  46 B is shown in  FIG. 15 . Surrounding parts of apparatus  20  are not shown in  FIG. 15  so as to aid in the ease of illustration of cam plate  46 B. The cam plate  46 B has an edge type cam track  44 B instead of the slot  44  of  FIG. 10 . The edge type cam track  44 B is maintained in contact with the reciprocating cam guide  42  by a tension spring  47 , which is schematically illustrated in  FIG. 15 . Any type of resilient return spring could be utilized in place of spring  47  to urge the cam track  44 B against cam guide  42 . With either the cam plate  46  of  FIG. 10  or the cam plate  46 B of  FIG. 15  the cam plate will reciprocate as the hammer  26  cycles. 
     A feed support block  50  can be positioned at the end of the cam plate  46  to facilitate the feeding of the clip string  02  into the clip receiving cavity  24 . At least one finger  52 , and preferably two fingers, is connected to the cam plate  46  through the feed support block  50 . Referring to  FIGS. 10 ,  11 , and  12 , the finger  52  has a flat end  51  for engaging the clip string  02  as the cam plate  46  reciprocates towards the barrel  22 , but the finger  52  also has a sloped side  53  for sliding past the clip string  02  as the cam plate  46  reciprocates away from the barrel  22 . 
     The finger  52  is pivotally connected to the feed support block  50  at a finger pivot point  57 , and a biasing spring  55  urges the finger  52  to engage an individual clip  04  of the clip string  02  as the cam plate  46  reciprocates towards the barrel  22 . The finger pivot point  57  allows the finger  52  to ratchet back past the clip string  02  as the cam plate  46  moves away from the barrel  22 . Therefore, the clip string  02  sits still as the cam plate  46  reciprocates away from the barrel  22 , but the clip string  02  is advanced into the clip receiving cavity  24  as the cam plate  46  reciprocates towards the barrel  22 . The clip feed assembly  40  does not utilize a spring or urging device at the back end of the clip string  02  to advance the clips  04  into the clip receiving cavity  24 . The above described mechanism engages the hammer  26  with the clip feed assembly  40  so the cycling of the hammer  26  provides the force to urge the clip string  02  into the clip receiving cavity  24 . 
     In the preferred embodiment, the finger  52  has an angled back end  59  which can be pressed to disengage the finger  52  from the clip string  02 . When disengaged, the clip string  02  can be withdrawn from the clip receiving cavity  24  without the finger  52  retaining any of the individual clips  04 . 
     The clip string  02  is supported by a clip track  54  when inserted into the bar connecting apparatus  20 . The clip track  54  can engage the clip string  02  from either the top or the bottom. Referring now to  FIGS. 1 ,  9 , and  13 , the clip track  54 A can engage the clips  04  by the cradle  15  defined by the upper body  14 , or from the top. When the clip string  02  is engaged from the top, the clip track  54 A extends through the clip receiving cavity  24 A. The clips  04  are then released distally from the clip track  54 A. When the clip track  54 A extends through the clip receiving cavity  24 A, the hammer  26 A has an indentation  56  for receiving the clip track  54 A as the hammer  26 A reciprocates. The hammer  26 A has at least one, and preferably two, legs  58  on the side of the indentation  56 . The legs  58  contact the upper body  14  of the terminal clip  06  to propel the clip out of the barrel  22 A. As the legs  58  propel the terminal clip  06  out of the barrel  22 A, the clip track  54 A is received in the indentation  56  such that the legs  58  pass beside the clip track  54 A. 
     In the embodiment where the clip track  54  engages the clip string  02  from the bottom, the clip track  54  does not extend through the clip receiving cavity  24 , as shown in  FIGS. 5 and 10 . The clip track  54  terminates at the clip receiving cavity  24  and the hammer  26  can be flat because there is no need to pass around the clip track  54 . Referring to  FIGS. 5 ,  10 , and  14 , because the clip track  54  does not hold the clip  04  in the clip receiving cavity  24 , at least one resilient retainer  60  can be used to secure the terminal clip  06  in the clip receiving cavity  24 . Preferably, four resilient retainers  60  comprised of ball bearing springs mounted in the clip receiving cavity  24  are used. The resilient retainer  60  releasably engages the terminal clip  06  in the clip receiving cavity  24  to prevent the terminal clip  06  from falling out of the barrel  22  before being expelled by the hammer. 
     Referring to  FIGS. 1 and 9 , the clip track  54 A is further comprised of at least a first portion  62  and a second portion  64 . The second portion  64  is dimensioned to frictionally engage and lightly hold the clip string  02 . The first portion of the clip track  62  has smaller dimensions which do not frictionally engage or hold the clip string  02 , so the clips  04  will easily slide across the first portion of the clip track  62 . This allows the clips  04  to be easily engaged with the first portion of the clip track  62 , and yet still be frictionally engaged and held in positioned by a shorter second portion  64 . The second portion of the clip track  64  is between the barrel  22 A and the first portion  62  so that the clip string  02  is frictionally engaged when in a position to enter into the clip receiving cavity  24 A. 
     Method of Connecting Bars 
     The current invention also includes a method of connecting bars, which is shown in  FIGS. 1 ,  5 , and  10 . The method includes providing a bar connecting apparatus  20  for applying clips  04  as described above. A clip string  02  is engaged with the clip track  54  of the bar connecting apparatus  20 , and then slid along the clip track  54  until at least one clip  04  is received in the clip receiving cavity  24 . The bar connecting apparatus  20  is then aligned with two transverse bars to be connected by an alignment head  28 . The alignment head  28  has two pair of notches  30 , so when the alignment head  28  is properly positioned each bar is engaged with one pair of the notches  30 . The bar connecting apparatus  20  is actuated, which reciprocates a hammer  26  in the barrel  22 . The hammer  26  contacts and expels the clip  04  received in the clip receiving cavity  24  such that the clip connects the bars. The cycling of the hammer  26  also cycles the clip feed assembly  40  to advance another clip  04  from the clip string  02  into the clip receiving cavity  24  for a subsequent clip application. The clip string  02  is advanced into the clip receiving cavity  24  in a direction transverse to the direction of reciprocation of the hammer. 
     Thus, although there have been described particular embodiments of the present invention of a new and useful BAR CONNECTING APPARATUS, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.