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 
       [0001]    This application is a Continuation-In-Part of co-pending U.S. Non-Provisional Patent Application Ser. No. 11/622,674 filed Jan. 12, 2007, entitled “BAR CONNECTING APPARATUS” which is hereby incorporated by reference. This application and application Ser. No. 11/622,674 both claim the 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. The present application also claims benefit of co-pending U.S. Provisional Patent Application Ser. No. 60/911,401 filed Apr. 12, 2007 entitled “BAR CONNECTING APPARATUS” which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    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. 
         [0004]    2. Description of the Related Art 
         [0005]    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. 
         [0006]    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. 
         [0007]    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. 
         [0008]    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 
       [0009]    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. 
         [0010]    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. 
         [0011]    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. 
         [0012]    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. 
         [0013]    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 
         [0014]      FIG. 1  is a perspective view of the clip string. 
           [0015]      FIG. 2  is a perspective view of a single clip engaged with transverse bars. 
           [0016]      FIG. 3  is a perspective view of the clip string when the feed rod is utilized. 
           [0017]      FIG. 4  is a perspective view of the clip string with teeth on the feed rod. 
           [0018]      FIG. 5  is a side view of the manually driven embodiment of the bar connecting apparatus. 
           [0019]      FIG. 6  is a side view of a distal portion of the bar connecting apparatus without the clip feed assembly. 
           [0020]      FIG. 7  is a front view of a distal portion of the bar connecting apparatus without the clip feed assembly. 
           [0021]      FIG. 8  is a side view of the manual drive portion of the bar connecting apparatus with an attached hammer. 
           [0022]      FIG. 9  is a side view of the pneumatically driven embodiment of the bar connecting apparatus. 
           [0023]      FIG. 10  is a side view of a distal portion of the bar connecting apparatus. 
           [0024]      FIG. 11  is a top view of a finger of the clip feed assembly. 
           [0025]      FIG. 12  is a top view of a clip string engaged by fingers of the clip feed assembly. 
           [0026]      FIG. 13  is a side view of the hammer having an indentation. 
           [0027]      FIG. 14  is a front view of a portion of the clip receiving cavity with resilient retainers. 
           [0028]      FIG. 15  is a side view illustrating an alternate design for the cam plate. 
           [0029]      FIG. 16  is a side view of an embodiment of the clip string. 
           [0030]      FIG. 17  is a side view of an embodiment of the bar connecting apparatus showing the clip feed assembly. 
           [0031]      FIG. 18  is a side view of an embodiment of the bar connecting apparatus with the barrel removed to display components within the barrel. 
           [0032]      FIG. 19  is a side view of the distal portion of the bar connecting apparatus 
           [0033]      FIG. 20  is a rear view of the distal portion of the bar connecting apparatus, with the clip feed assembly removed for clarity. 
           [0034]      FIG. 21  is a side view of the hammer with the hammer plate. 
           [0035]      FIG. 22  is a top view of the hammer with the hammer plate. 
           [0036]      FIG. 23  is a top view of the cam plate for the hammer plate embodiment of the invention. 
           [0037]      FIG. 24  is a side view of the cam plate for the hammer plate embodiment of the invention. 
           [0038]      FIG. 25  is a rear view of the finger for the hammer plate embodiment of the invention. 
           [0039]      FIG. 26  is a side view of the finger for the hammer plate embodiment of the invention. 
           [0040]      FIG. 27  is a side view of the hammer plate embodiment of a manually actuated bar connecting apparatus with the safety plate removed for clarity. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Clip String 
       [0041]    The Bar Connecting Apparatus utilizes a clip string  2  as depicted in  FIG. 1 . The clip string  2  is comprised of a plurality of connected individual clips  4 , wherein the last clip in the series is the terminal clip  6 . In the preferred embodiment, the clips  4  are comprised of plastic and each clip  4  has several components. Referring to  FIG. 2 , the seat  8  is adapted to engage and position a first bar  9 . Below the seat  8  are a plurality of hooks  10 , preferentially four hooks  10  per clip  4 , which are adapted to engage and position a second bar  11  transverse to the first bar  9 . The first bar  9  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 . 
         [0042]    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  4  can position a bar parallel to the second bar  11  in the cradle  15 , or it can position a first bar  9  in the seat  8 , but not both at the same time because the seat  8  and the cradle  15  receive bars in areas which interfere with each other. 
         [0043]    Each clip  4  in the clip string  2  is connected to at least one adjoining clip  4  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  4 , as long as the clips  4  are connected together. Each clip  4  has at least one connection point  16 , but multiple connection points  16  can be utilized if necessary. The clips  4  are connected such that every clip  4  in the clip string  2  has a consistent orientation. Preferably, the orientation is such that if a bar were received in the hooks  10  of the terminal clip  6 , the same bar could be simultaneously received in the hooks  10  of every other clip  4  in the clip string  02 . Therefore, there would be one axis defined by the hooks  10  of all of the clips  4  in a clip string  02 . Similarly, the cradles  15  defined by the upper bodies  14  of the clips  4  would also be aligned on a single axis. 
         [0044]    In an alternative embodiment, the clips  4  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  4  to the feed rod  18 . The feed rod  18  can be positioned anywhere along the side of the clip string  2 B as long as the clips  4  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  2 B, as shown in  FIG. 4 . Also, if the feed rod  18  is utilized, each individual clip  4  does not necessarily touch or directly contact the neighboring clip  4 . The clips  4  are connected to the feed rod  18 , and not to each other, so the clips  4  are not held in direct contact with other clips  4  in the clip string  2 B. 
         [0045]    Every clip string  2 B has only one sized clip  4 , but every clip string  2 B does not necessarily have the same sized clip  4 . The clips  4  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  4 . Although the size of a clip  4  in different clip strings  2 B would vary, the feed rod  18  allows the spacing between neighboring clips  4  to be constant. That is, the distance from the front of a larger clip  4  to the front of a neighboring larger clip  4  in one clip string  2 B would be the same as the distance from the front of a smaller clip  4  to the front of a neighboring smaller clip  4  in another clip string  2 B. When a feed rod  18  is utilized, this consistent spacing is possible because the clips  4  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  4  of different sizes without having to adjust or change the clip feed mechanism. 
         [0046]    A third embodiment of the clip string  2 C is shown in  FIG. 16 . Similar components are given the same names, but the identification numbers are denominated by a “C,” for the sake of clarity. Every clip  4 C in a clip string  2 C is the same size, but the third embodiment allows for clips strings  2 C having different sized clips  4 C to maintain consistent spacing between the clips  4 C without the use of a feed rod. 
         [0047]    The clip string  2 C has a length  3 C, with each individual clip  4 C having at least one adjacent clip. The terminal clip  6 C would only have one adjacent clip  4 C, whereas each clip  4 C in the middle of the clip string  2 C would have two adjacent clips  4 C. Each clip  4 C is oriented with the cradle  15  defined by the upper body  14  aligned perpendicular to the clip string length  3 C. When the cradle  15  is perpendicular to the clip string length  3 C, a bar received in the cradle  15  of the clip  4 C would be perpendicular to the length  3 C of the clip string  2 C. This orientation is ninety degrees from the orientation shown in  FIG. 1 , where a bar received in the cradle  15  of each clip  4  would be parallel to the length of the clip string. In  FIG. 16  each clip  4 C is still consistently oriented, but the orientation has shifted. It is also possible to orient each clip  4 C with the cradle  15  aligned parallel to the length  3 C of the clip string  2 C. 
         [0048]    Consistent spacing between different sized clips  4 C in different clip strings  2 C is achieved by providing a connection point  16 C with a length  17 C. The connection point  16 C is also referred to as a tab  16 C, and the length  17 C of the tab  16 C varies between clip strings  2 C having clips  4 C of different size. By providing shorter tabs  16 C for clip strings  2 C with larger clips  4 C, the spacing between the clips  4 C can be kept consistent for clip strings  2 C having different sized clips  4 C. Therefore, the distance from the front of one clip  4 C to the front of an adjacent clip  4 C is the same for two different clip strings  2 C which have clips  4 C of different sizes. The length  17 C of the tab  16 C serves to hold adjacent clips  4 C apart, so they don&#39;t touch, with the adjacent clips  4 C separated by the tab length  17 C. When the clip string  2 C is flexed, adjoining clips  4 C may touch, but normally they would be apart. 
         [0049]    The tab  16 C has an indent  13 C to facilitate breaking of the tab  16 C when the clip  4 C is applied to connect bars. The terminal clip  6 C becomes separated from the clip string  2 C when used to connect bars, and the indent  13 C provides a breaking point on the tab  16 C to aid in separating the terminal clip  6 C. Each clip  4 C is comprised of plastic, and preferably includes four hooks  10 ,  4  upper bodies  14 , and two joining portions  12  which each connects two hooks  10 , as best seen in  FIG. 2 . Each upper body  14  is connected to one other upper body  14  in each clip  4 . 
       Bar Connecting Apparatus 
       [0050]    The clip string  2  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  6  of the clip string  2  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  4  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  6  and expels the terminal clip  6  out the distal end of the barrel  23 . 
         [0051]    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  6  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  6  connects the bars. After the terminal clip  6  is ejected the hammer  26  reciprocates proximally, the next clip  4  in the clip string  2  is advanced into the clip receiving cavity  24  and becomes the new terminal clip  6 , and the clip applying process is ready to be repeated. 
         [0052]    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  9 , which is on top, is engaged in the deeper pair of notches  30  and the second bar  11 , which is underneath the first bar  9 , 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  9 ,  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. 
         [0053]    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  6  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  6  can be introduced into the clip receiving cavity  24 . 
         [0054]      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. 
         [0055]    The alignment head  28  includes two pair of notches  30 ,  30 B, which are further designated as a first and second pair of notches  30 ,  30 B, as seen in  FIGS. 6  and  7 . The first pair of notches  30  are deeper than the second pair of notches  30 B. This allows the first transverse bar  9 , which is above the second bar  11 , to be engaged in the first pair of notches  30 , and the second, bottom transverse bar  11  to be engaged in the second pair of notches  30 B. The transverse bars  9 ,  11  are perpendicular to each other, and the alignment head  28 C positions the barrel  22 C perpendicular to both bars  9 ,  11 . 
       Clip Feed Assembly 
       [0056]    The clip feed assembly  40  advances the clip string  2  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. 
         [0057]    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  40  operation 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 the cam plate  46 . 
         [0058]    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. 
         [0059]    A feed support block  50  can be positioned at the end of the cam plate  46  to facilitate the feeding of the clip string  2  into the clip receiving cavity  24 , as shown in  FIG. 10 . 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  2  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  2  as the cam plate  46  reciprocates away from the barrel  22 . 
         [0060]    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  4  of the clip string  2  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  2  as the cam plate  46  moves away from the barrel  22 . Therefore, the clip string  2  sits still as the cam plate  46  reciprocates away from the barrel  22 , but the clip string  2  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  2  to advance the clips  4  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  2  into the clip receiving cavity  24 . 
         [0061]    In one embodiment, the finger  52  has an angled back end  59  which can be pressed to disengage the finger  52  from the clip string  2 . When disengaged, the clip string  2  can be withdrawn from the clip receiving cavity  24  without the finger  52  retaining any of the individual clips  4 . 
         [0062]    The clip string  2  is supported by a clip track  54  when inserted into the bar connecting apparatus  20 . The clip track  54  can engage the clip string  2  from either the top or the bottom. Referring now to  FIGS. 1 ,  9 , and  13 , the clip track  54 A can engage the clips  4  by the cradle  15  defined by the upper body  14 , or from the top. When the clip string  2  is engaged from the top, the clip track  54 A extends through the clip receiving cavity  24 A. The clips  4  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  6  to propel the clip out of the barrel  22 A. As the legs  58  propel the terminal clip  6  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. 
         [0063]    In the embodiment where the clip track  54  engages the clip string  2  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  4  in the clip receiving cavity  24 , at least one resilient retainer  60  can be used to secure the terminal clip  6  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  6  in the clip receiving cavity  24  to prevent the terminal clip  6  from falling out of the barrel  22  before being expelled by the hammer. 
         [0064]    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  2 . The first portion of the clip track  62  has smaller dimensions which do not frictionally engage or hold the clip string  2 , so the clips  4  will easily slide across the first portion of the clip track  62 . This allows the clips  4  to be easily engaged with the first portion of the clip track  62 , and yet still be frictionally engaged and held in position 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  2  is frictionally engaged when in a position to enter into the clip receiving cavity  24 A. 
       Clip Feed Assembly with a Hammer Plate 
       [0065]    An alternate embodiment of the clip feed assembly is shown in  FIGS. 17 ,  18 ,  19  and  20 . In the description of this embodiment, similar components are given the same name and number, but are denoted by the suffix “C.” In  FIG. 18 , the barrel has been removed to better show the internal parts. 
         [0066]    A barrel  22 C has a clip receiving cavity  24 C and a slot  25 C extending parallel to the length of the barrel  22 C. The hammer  26 C includes a hammer plate  27 C, which extends through the barrel slot  25 C. The hammer  26 C reciprocates longitudinally within the barrel  22 C, and the hammer plate  27 C reciprocates external and parallel to the barrel  22 C through the barrel slot  25 C. The hammer plate  27 C has an angled section  29 C, which is angled relative to the length of the barrel  22 C. This angled section  29 C works as an inclined plane. The hammer  26 C can be hollow and include holes to reduce weight, as better seen in  FIGS. 21 and 22 . The cycling of the hammer  26 C provides the force to cycle the clip feed assembly  40 C, which urges a clip  4 C into the clip receiving cavity  24 C. 
         [0067]    A cam plate  46 C is shown in isolation in  FIGS. 23 and 24 . The cam plate has an inclined section  49 C, at least one running fit  66 C, and can include holes to reduce weight. The running fit  66 C has a spring pocket  68 C to receive and support a tension spring. The spring pocket  68 C has a larger diameter than the running fit  66 C. The inclined section  49 C faces the angled section  29 C of the hammer plate  27 C, as better seen in  FIGS. 17 and 18 . The inclined section  49 C is positioned to be angled relative to the length of the barrel  22 C. A guide shaft  70 C is received in each running fit  66 C, and serves to guide the cam plate  46 C as the cam plate  46 C reciprocates. The guide shaft  70 C is fixed in one position, so the cam plate  46 C reciprocates parallel to the guide shaft  70 C. The running fit  66 C is dimensioned slightly larger than the guide shaft  70 C, so the cam plate  46 C will be held at a relatively constant angle to the guide shaft  70 C as the cam plate  46 C reciprocates up and down on the guide shaft  70 C. In this embodiment, the cam plate  46 C does not pivot on a pivot point. 
         [0068]    As seen in  FIG. 27 , a space  45 C between the hammer plate  27 C and the cam plate  46 C, when the hammer  26 C has reciprocated proximally, allows for the application of a smaller force to initiate the actuation motion of the hammer  26 C, as shown in  FIG. 27 . This is because the hammer plate  27 C will have developed some momentum when contacting and initiating the cycling of the cam plate  46 C. This space  45 C between the hammer plate  27 C and cam plate  46 C is especially useful for a manually actuated bar connecting apparatus  20 D shown in  FIG. 27 , because it requires less strength from the operator. Even though there is a space  45 C between the hammer plate  27 C and the cam plate  46 C, the angled section  29 C and the inclined section  49 C still face each other. 
         [0069]    Referring again to  FIGS. 17 and 18 , the guide shaft  70 C is received between the barrel  22 C and a guide shaft bracket  72 C. The guide shaft  70 C has a first end  74 C, which is connected and secured to the barrel  22 C, and a second end  76 C, which is secured to the guide shaft bracket  72 C. A compression spring  47 C is received about the guide shaft  70 C. The compression spring  47 C serves to urge the cam plate  46 C towards the hammer plate  27 C. The compression spring terminates on one end in the cam plate spring pocket  68 C, and on the other end in a guide shaft bracket spring pocket  78 C. The compression spring  47 C could be mounted in many alternative ways, and it could assume a form different than a coil spring, as long as it biases the cam plate  46 C towards the hammer plate  27 C. 
         [0070]    As the hammer  26 C reciprocates distally, the angled section  29 C of the hammer plate  27 C pushes into the inclined section  49 C of the cam plate  46 C. The guide shaft  70 C forces the cam plate  46 C to only move parallel to the guide shaft  70 C, so the force of the hammer plate angled section  29 C on the cam plate inclined section  49 C is translated into a lateral motion of the cam plate  46 C along the guide shaft  70 C. Therefore, as the hammer  26 C reciprocates distally, the cam plate  46 C reciprocates laterally away from the barrel  22 C. When the hammer  26 C reciprocates proximally, the compression spring  47 C urges the cam plate  46 C towards the hammer  26 C, so the cam plate reciprocates laterally towards the barrel  22 C. 
         [0071]    At least one safety plate  80 C is mounted to cover the workings of the hammer plate  27 C and the cam plate  46 C. Therefore, the safety plate  80 C is adjacent to the hammer plate  27 C and the cam plate  46 C. The safety plate  80 C is indicated by long and short dashed lines in  FIGS. 17 and 19 , with the parts underneath the safety plate  80 C shown for clarity, even though the parts would not be visible underneath the safety plate  80 C. Preferably, there would be a safety plate  80 C on both sides of the bar connecting apparatus  20 C, to provide better protection from the workings of the hammer plate  27 C and the cam plate  46 C. The safety plate  80 C is connected to the barrel  22 C, and serves as a mount for the guide shaft bracket  72 C. It is also possible to connect a bracket  81 C between the safety plate  80 C and the handle  82 C of the bar connecting apparatus  20 C. The bracket  81 C can include a grip  83 C, if desired. The bracket  81 C and grip  83 C are shown in phantom lines in  FIG. 17 . 
         [0072]    A finger  52 C is pivotally connected to the cam plate  46 C at the distal end of the cam plate  46 C. The finger  52 C is for engaging and advancing a clip  4 C into the clip receiving cavity  24 C with each reciprocation of the cam plate  46 C. The finger  52 C is shown in isolation in  FIGS. 25 and 26 . The finger  52 C has a flat end  51 C for engaging and advancing a clip. The finger  52 C also has a sloped side  53 C, to slide past a clip without engaging it. A catch portion  59 C serves to support the finger  52 C and prevent it from pivoting backwards, or towards the sloped side  53 C, when engaging a clip and advancing it forwards. An angled portion  61 C allows the finger to pivot forward, or towards the flat end  61 C, when the finger  52 C slides backwards past a clip to engage and advance a new clip forward. The finger  52 C has a pivot point  57 C, which is connected between two faces  69 C on the cam plate  46 C, as seen in  FIGS. 23 and 26 . The catch  59 C abuts an edge of the cam plate faces  69 C as seen in  FIG. 18 , which prevents the finger  52 C from pivoting backwards. The angled section  61 C abuts the edges of the cam plate faces  69 C after the finger  52 C has pivoted forward enough to allow the finger  52 C to slide away from barrel  22 C past a clip, so the forward pivoting of the finger  52 C is controlled by the angled section  61 C. 
         [0073]    Referring now to  FIG. 19 , the finger  52 C is received between finger brackets  84 C, which are mounted to the safety plate  80 C. When the hammer moves distally the cam plate  46 C moves away from the barrel  22 C, and the acceleration of the cam plate  46 C causes the finger  52 C to pivot towards the barrel  22 C on the finger pivot point  57 C. When the hammer moves proximally, the cam plate  46 C reverses direction and accelerates toward the barrel  22 C. This acceleration causes the finger  52 C to pivot away from the barrel  22 C on the pivot point  57 C. When the finger  52 C pivots away from the barrel  22 C, the flat end  51 C is positioned to engage and advance a clip  4 C towards the barrel  22 C. 
         [0074]    A resilient catch  86 C is mounted in the finger bracket  84 C. The resilient catch  86 C is positioned to engage a clip  4 C received on the clip track  54 C and provide resistance to the clip  4 C sliding backwards, or away from the barrel  22 C. In particular, the resilient catch  86 C contacts a surface of a clip  4 C that is facing away from the barrel  22 C. The resilient catch  86 C is mounted in the finger bracket  84 C, but it could be mounted anywhere, as long as it is positioned adjacent to the clip track  54 C for contacting a surface of a clip  4 C that is facing away from the barrel  22 C. The resilient catch  86 C provides some resistance, but will allow motion past it if sufficient force is applied. 
         [0075]    A clip track  54 C is connected to the barrel  22 C adjacent to the clip receiving cavity  24 C, but does not extend through the barrel  22 C. The clip track  54 C supports the clips  4 C in the seat  8 , so the connection point  7  between two upper bodies  14  is transverse to the clip track  54 C, as seen in  FIGS. 19 ,  2 , and  16 . The finger  52 C engages this connection point  7 , which provides a contact surface perpendicular to the motion of the finger  52 C. This broad contact surface facilitates the use of different sized clips  4 C in the same bar connecting apparatus  20 C, because different sized clips will still have the connection point  7  positioned above the clip track  54 C in the same manner. The finger  52 C moves a set distance with each reciprocation of the cam plate  46 C, so the consistent spacing of the clips  4 C in the clip string  2 C allows for different sized clips  4 C to be used in the bar connecting apparatus  20 C. 
         [0076]    The clip track  54 C is parallel to the guide shaft  70 C, so the finger  52 C will move parallel to the clip track  54 C, as best seen in  FIGS. 17 ,  18  and  19 . The finger  52 C is connected to the cam plate  46 C, and the cam plate  46 C moves parallel with the guide shaft  70 C, so the finger  52 C also moves parallel with the guide shaft  70 C. The clip track  54 C can be perpendicular to the barrel  22 C, but it could also be at another angle, as long as it is parallel to the guide shaft  70 C. 
       Method of Connecting Bars 
       [0077]    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  4  as described above. A clip string  2  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  4  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  4  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  4  from the clip string  2  into the clip receiving cavity  24  for a subsequent clip application. The clip string  2  is advanced into the clip receiving cavity  24  in a direction transverse to the direction of reciprocation of the hammer. 
         [0078]    The terminal clip  6 C of the clip string  4 C is inserted into the clip receiving cavity  24 C of the bar connecting apparatus  20 C, as seen in  FIGS. 16 through 19 . After the terminal clip  6 C has been ejected to connect bars, the next clip  4 C becomes the new terminal clip  6 C, is advanced into the clip receiving cavity  24 C by the clip feed assembly  40 C, and the bar connecting apparatus is ready for a subsequent clip  4 C application. 
         [0079]    The alignment head  28 C has two pair of notches  30 C,  30 D, wherein each pair of notches  30 C,  30 D has a different depth than the other pair, so the alignment head  28 C will engage two transverse bars  9 C,  11 C to be connected with one bar  9 C on top of the other  11 C. Each bar  9 C,  11 C is engaged in one pair of notches  30 C,  30 D. 
         [0080]    The method includes the providing of at least a first and second clip string  2 C, wherein the size of the clips  4 C in each clip string  2 C is constant, but the clips  4 C in the first clip string  2 C are of a different size than the clips  04 C of the second clip string  2 C. The distance between the front ends of adjacent clips in the first and second clip string is the same. One clip string  2 C is selected such that the clips  4 C are sized properly for the bars to be connected. The selected clip string  2 C is then inserted into the clip receiving cavity  24 C for application of the clips  4 C. 
         [0081]    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.