Abstract:
A clamp system for an elongate member, comprising first and second clamp members, an actuator member, and an actuator system. The actuator member defines an actuator cam surface and is supported for movement between first and second actuator positions. The second clamp member defines a clamp cam surface and is supported for movement between first and second clamp positions. The actuator system displaces the actuator member between first and second actuator positions. As the actuator member moves from the first actuator position to the second actuator position, the actuator cam surface engages the clamp cam surface to cause the second clamp member to move towards the first clamp member, thereby clamping a portion of the elongate member between the first and second clamp members.

Description:
RELATED APPLICATIONS 
     This application claims priority of U.S. Provisional Patent Application Ser. No. 60/722,748 filed Sep. 30, 2005, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to clamp systems and methods for use by pile drivers and, more particularly, to clamp systems and methods adapted to allow a rebar cage to be connected to a pile driver. 
     BACKGROUND OF THE INVENTION 
     Construction projects often require the insertion of and removal of elongate members in the earth. Elongate members can take many forms, such as hollow cylinders (pipe piles, caissons), solid cylinders (concrete or wooden piles), and sheets (sheet piles). 
     To facilitate insertion or removal of an elongate member without excavation, pile driving systems and methods may be used. A pile driving system or method can employs a static or repetitive driving force along a longitudinal axis of the elongate member. A static driving force may be created by weight applied to an upper end of the elongate member and/or a gear drive or the like that applies a crowding force to the elongate member. A repetitive driving force may be created by a drop hammer, diesel hammer, or the like. When directed towards the ground, the driving force can be sufficient to cause the elongate member to enter the ground, depending upon soil conditions and the like. When directed away from the ground, the driving force extracts the elongate member from the ground. 
     The present invention is directed to a pile driving system or method in which a static driving force is combined with a vibrational force. A vibration system typically applies the vibrational force to the elongate member in combination with a static driving force. Under most conditions, the vibrational force significantly enhances the ability of the pile driving system or method both to insert and to extract an elongate member. When a pile driving system or method employs vibrational forces to insert or extract an elongate member, a vibration suppression system is often used to inhibit transmission of these forces back to a support system (e.g., crane, spotter) used to position the pile driving system and/or elongate member. 
     To ensure that the vibrational forces are effectively transmitted to the elongate member, clamping system and methods are typically employed. A clamping system or method is typically configured to apply a clamping force that substantially rigidly connects the vibrational device to the elongate member. 
     A clamping system for a pile driving system or method usually comprises a fixed clamp member and a movable clamp member. The fixed clamp member is substantially rigidly attached to a clamp housing, a portion of the elongate member is placed between the fixed clamp member and the movable clamp member, and the movable clamp member is displaced relative to the clamp housing such that the portion of the elongate member is gripped between fixed and movable clamp members. 
     The geometry of the clamp members is typically configured based on the geometry and material of the elongate member. For example, clamp members for a metal sheet pile would be generally flat, perhaps with a surface textured to increase friction between the clamp members and the pile. On the other hand, the clamp members for a wooden pile might be curved with teeth that will penetrate the wooden pile to reduce slippage. 
     One special form of an elongate member is a rebar cage that can be used as a pile by itself or to reinforce a poured concrete pile. A rebar cage typically comprises longitudinal bars and ring bars. The ring bars are welded around longitudinal bars to form a generally cylindrical structure that is hollow and has a discontinuous surface. 
     The shape and construction of a rebar cage cannot effectively be secured to a vibrational device using conventional clamp assemblies with a fixed and movable clamp member. The need thus exists for improved clamping systems and methods for elongate members such as rebar cages. 
     SUMMARY OF THE INVENTION 
     The present invention may be embodied as a clamp system for an elongate member comprising first and second clamp members, an actuator member, and an actuator system. The actuator member defines an actuator cam surface and is supported for movement between first and second actuator positions. The second clamp member defines a clamp cam surface and is supported for movement between first and second clamp positions. The actuator system displaces the actuator member between first and second actuator positions. As the actuator member moves from the first actuator position to the second actuator position, the actuator cam surface engages the clamp cam surface to cause the second clamp member to move towards the first clamp member, thereby clamping a portion of the elongate member between the first and second clamp members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of a pile driving system using a clamp system of the present invention; 
         FIG. 2  is an end perspective view of a rebar cage of the type that may be clamped by the clamp system used by the pile driving system of  FIG. 1 ; 
         FIG. 3  is a front elevation view of a driving assembly of the pile driving system, the driving assembly incorporating the clamp system of the present invention; 
         FIG. 4  is a side elevation view depicting the driving assembly of  FIG. 3 ; 
         FIG. 5  is a bottom plan view depicting the clamp system of  FIGS. 1 and 3 ; 
         FIGS. 6 and 7  are longitudinal cutaway views of the clamp system of  FIG. 3  taken along lines  6 - 6  in  FIG. 3 ; 
         FIG. 8  depicts a side elevation view of a radial clamp assembly used by the clamp system of the present invention; 
         FIGS. 9 and 10  are top section views taken along lines  9 - 9  in  FIG. 6  illustrating the radial clamp assembly in open and closed positions; 
         FIG. 11  is a side elevation view illustrating the engagement of the driving assembly of  FIG. 3  with the rebar cage of  FIG. 2 ; 
         FIGS. 12 and 13  are schematic views depicting the operation of the clamp system of the present invention in unclamped and clamped configurations; 
         FIG. 14  is a top plan cutaway view depicting the radial clamp assembly of the present invention; 
         FIG. 15  is a section view taken along lines  15 - 15  in  FIG. 12 ; and 
         FIG. 16  is a section view taken along lines  16 - 16  in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to  FIG. 1  of the drawing, depicted at  20  therein is a pile driving system employing a clamp system  22  constructed in accordance with, and embodying, the principles of the present invention. The clamp system  22  is configured to engage a rebar cage  24  during driving of the rebar cage  24  into a portion  26  of the earth surface. 
     The pile driving system  20  comprises a crane  30  from which is suspended a crane line  32  and a crane bar  34 . A drive assembly  36  is attached to and suspended from the crane bar  34 , and the clamp system  22  forms a part of the drive assembly  36 . In the situation depicted in  FIG. 1 , the crane  30  locates the crane line  32  such that the rebar cage  24  is suspended above a desired location  36  on the earth surface  26 . 
     As shown in  FIGS. 1 and 2 , the example rebar cage  24  comprises a plurality of longitudinal bars  40  and a plurality of ring bars  42 . The longitudinal bars  40  and ring bars  42  are welded or otherwise rigidly connected such that the rebar cage  24  is relatively rigid. 
     Turning now to  FIGS. 3 and 4  of the drawing, the drive assembly  36  will now be described in further detail. The drive assembly  36  comprises a lead assembly  50 , a suppressor system  52 , a vibro system  54 , and the clamp system  22 . 
     The lead assembly  50  comprises first and second lead lines  60  and  62  that are connected to the crane bar  34 . The lead lines  60  and  62  are connected to first and second pivot yokes  64  and  66 . The pivot yokes  64  and  66  in turn receive pivot pins  70  and  72 . The pivot pins  70  and  72  are in turn connected to first and second side arms  74  and  76 . The side arms  74  and  76  are in turn connected to the suppressor system  52 . 
     The example pivot pins  70  and  72  of the lead assembly  50  are angle members comprising first portions  80  that are substantially collinear along a lateral axis A of the system  20  and second portions that are substantially vertical and parallel to each other and to a longitudinal axis B of the system  20 . 
     The suppressor system  52  comprises a suppressor housing  90 , a center plate  92 , and resilient members  94  connected between the housing  90  and the center plate  92 . The resilient members  92  inhibit transmission of forces between the housing  90  and the center plate  92 . The side arms  74  and  76  are rigidly connected to the suppressor housing  90  as perhaps best shown in  FIG. 4 . 
     The vibro system  54  comprises a vibro housing  120  that rotatably supports eccentric weights  122  and  124 . Motors  126  and  128  rotate the weights  122  and  124  in opposition to each other such that lateral forces are substantially cancelled and longitudinal forces are summed to create vibrational forces along a longitudinal axis B of the drive assembly  36 . The vibro housing  120  is rigidly connected to the center plate  92  of the suppressor system  52  such that transmission of the vibrational forces to the lead assembly  50  is inhibited. 
     Referring now to  FIGS. 5-10 , the clamp system  22  will be described in further detail. The clamp system  22  comprises a clamp housing  130  and a radial clamp assembly  132 . 
     The clamp housing  130  comprises a first wall portion  134 , a second wall portion  136 , and a third wall portion  138 . As perhaps best shown in  FIG. 6 , the first wall portion  134  of the clamp housing  132  defines a piston chamber  140 , while the third wall portion  138  defines a clamp chamber  142 . A shaft opening  144  is defined by the second wall portion  136 . The clamp housing  130  further comprises a mounting flange  146  that is rigidly connected to the vibro housing  120  such that vibrations of the vibro housing  120  are transmitted to the clamp housing  130 . 
     The example radial clamp assembly  132  comprises a piston member  150 , a plurality of clamp members  152 , and a plurality of guide rods  154 . The piston member  150  comprises a piston portion  160 , a shaft portion  162 , and a cam portion  164 . The piston portion  160  is arranged within the piston chamber  140  and defines a curved surface  170  and first and second annular surfaces  172  and  174 . The piston portion  160  and shaft portion  162  divide the piston chamber  140  into a first chamber portion  166  and a second chamber portion  168 . The shaft portion  162  extends from the piston chamber  140  into the clamp chamber  142  through the shaft opening  144 . 
     The cam portion  164  of the piston member  150  lies at least partly within the clamp chamber  142  and defines a first cam surface  176 . The clamp members  152  are arranged within the clamp chamber  142  and define second cam surfaces  178  that are complementary to the first cam surface  166 . More specifically, the clamp members  152  are arranged between the cam portion  164  of the piston member  150  and the third wall portion  138  of the clamp housing  136  such that the first and second cam surfaces  166  and  168  are in contact with each other. 
     By injecting hydraulic fluid into the chamber portions  166  and  168 , the piston member  150  can be displaced relative to the clamp housing  130 . In particular, by injecting fluid into the second chamber portion  168  as shown by arrow C and allowing fluid to flow out of the first chamber portion  168  as shown by arrow D in  FIG. 6 , fluid acts on the surface  174  of the piston portion  160 . Fluid acting on the piston portion  160  causes displacement of the piston member  150  relative to the clamp housing  130  as shown by a comparison of  FIGS. 6 and 7 . 
     The first and second cam surfaces  176  and  178  engage each other such that movement of the piston member  150  along the longitudinal axis B displaces the clamp members  152  radially from the longitudinal axis B. If the piston member  150  moves towards the vibro housing  120 , the clamp members  152  are displaced outwardly. If the piston member  150  moves away from the vibro housing  120 , the clamp members  152  are allowed to move inwardly. 
     The guide rods  154  are each associated with one of the clamp members  152  and define a threaded end  180 , a shaft portion  182 , and a bearing portion  184 . The threaded end  180  is secured to the clamp member  152  associated therewith. The shaft portions  182  extend through guide passageways  186  formed in the third wall portions  138  of the clamp housing  130 . 
     Attached to the clamp housing  130  at each of the guide passageways  186  are spring housings  190 . Each spring housing  190  defines a spring chamber  192 , and a biasing spring  194  is contained within each spring chamber  192 . The bearing portions  184  of the guide rods  154  are located within the spring chambers  192 . The biasing springs  194  act on the bearing portions  184  to bias the guide rods  154 , and thus the clamp members  152  attached thereto, radially inwardly. 
     The biasing springs  194  thus hold the first and second cam surfaces in contact as the piston member  150  moves through its full range of motion. Accordingly, as the piston member  150  is displaced away from the vibro housing  120 , the biasing springs  194  force the clamp members  152  radially inwardly away from the third wall portions  138 . 
     In use, the piston member  150  is displaced into a distal position shown in  FIGS. 6 and 9  to allow the longitudinal bars  40  of the rebar cage  24  to be arranged between the a first clamp surface  196  of the clamp members  152  and a second clamp surface  198  of the third wall portion  138 . The piston member  152  is then displaced into a proximal position as shown in  FIGS. 7 and 10  such that the clamp members  152  clamp the longitudinal bars  40  of the rebar cage  24  between the first and second clamp surfaces  196  and  198 . Spacer sleeves may be placed along at least part of the first clamp surface  198  to accommodate rebar cages  24  of different diameters. 
     As shown in  FIGS. 8 and 10 , in addition to the first clamp surfaces  196 , the clamp members  152  define complementary side surfaces  199  that are angled with respect to the system axes A and B. These angled side surfaces  199  overlap to ensure continuous contact between the longitudinal bars  40  and the clamp members  152  throughout the entire 360° arc defined by the second clamp surface  198  when the clamp members are in the radially outward position shown in  FIGS. 7 and 10 . 
     Referring now to  FIG. 11 , it can be seen that the lead assembly  50  is sized and dimensioned such that the entire drive system  36  can be rotated about the lateral axis A until the longitudinal axis is substantially horizontal. The lead assembly  50  thus allows the drive system  36  to be displaced to engage the rebar cage  24  when the rebar cage  24  itself is substantially horizontal (e.g., stored parallel to the ground). 
     Referring now to  FIGS. 12-16 , depicted therein is a second embodiment of a clamp system  220  constructed in accordance with, and embodying the principles of the present invention. 
     The clamp system  220  comprises a clamp housing  222  and a clamp assembly  224 . The clamp housing  222  defines a chamber portion  230 , a clamp portion  232 , and a divider wall  234 . The chamber portion  230  defines a piston chamber  236 , and the divider wall  234  defines a shaft opening  238 . The chamber portion  230  further defines a longitudinal system axis  238 . The example clamp assembly  224  comprises a piston member  240 , a plurality of first clamp members  242 , a plurality of second clamp members  244 , and a plurality of biasing springs  246 . 
     The first clamp members  242  each comprise an engaging portion  260 , a spring collar  262 , and a cam portion  264 . First cam surfaces  266  are formed on each of the cam portions  264 . Guide portions  268  extend from the clamp housing  222  to support the clamp members  242  for radial movement relative to the system axis  238  as generally shown in  FIG. 14 . The biasing springs  246  are located between the spring collars  262  and one of the guide portions  268  such that the biasing springs  246  force the clamp members  242  radially inwardly towards the system axis  238 . 
     The piston member  240  defines a piston portion  270 , a shaft portion  272 , and a cam portion  274 . The cam portion defines a second cam surface  276 . The piston portion  270  is arranged in the piston chamber  236 , while the shaft portion  272  extends through the shaft opening  238 . The cam portion  274  is arranged such that the first cam surfaces  266  are held by the biasing springs  246  in contact with the second cam surface  276 . 
     As generally described above, the introduction of hydraulic fluid into the piston chamber  236  forces the piston member  240  in either direction along the longitudinal system axis  238 . Displacing the piston member  240  along system axis  238  such that the cam portion  274  moves closer to the divider wall  234  moves the clamp members  242  radially outwardly as shown in  FIG. 13 . Displacing the piston member  240  in the opposite direction allows the biasing springs  246  to move the clamp members  242  radially inwardly to the position shown in  FIG. 12 . A rebar cage such as the cage  24  described above may thus be clamped between the engaging portions  260  and the second clamp members  244 . 
       FIGS. 15 and 16  illustrate a clamp adjusting system  280  that may be used as part of the clamp systems  22  and  220  of the present invention. In particular, the second clamp members  244  may comprise lock members  282  that are slidably mounted in radially oriented dovetail slots  284  formed in the clamp portion  232  of the clamp housing  222 . Bolts  286  extend through a mounting plate portion  288  of the second clamp members  244  and into the lock members  282 . The bolts  286  may be loosened to allow relative movement between the clamp members  244  and the clamp housing  222  and or tightened to inhibit such relative movement. 
     The clamp adjusting system  280  thus allows the relative position between the clamp members  244  and the clamp housing  222  to be adjusted to accommodate different rebar cages. 
     While an effort has been made to describe some alternatives to the preferred embodiment, other alternatives will readily come to mind to those skilled in the art. Therefore, it should be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not intended to be limited to the details given herein.