Abstract:
A clamp assembly for attaching a pile to a pile driving apparatus for inserting and/or extracting the pile, comprising a housing; a first pivot assembly pivotably attached to the housing; a first gripping assembly rotatably attached to the first pivot assembly; a second pivot assembly pivotably attached to the housing; a second gripping assembly rotatably attached to the second pivot assembly; a first actuating assembly for displacing the first pivot assembly and the first gripping assembly such that first gripping assembly moves towards the second gripping assembly; and a second actuating assembly for displacing the second pivot assembly and the second gripping assembly such that second gripping assembly moves towards the first gripping assembly; wherein as the first and second gripping assemblies move towards each other, the pile is gripped between the first and second gripping assemblies to inhibit relative movement between the housing and the pile.

Description:
RELATED APPLICATIONS 
     This application claims priority of U.S. Provisional Patent Application Ser. No. 60/125,930, which was filed on Mar. 23, 1999. 
    
    
     TECHNICAL FIELD 
     The present invention relates to clamps that allow vibratory devices to be attached to elongate members and, more particularly, such clamps that are adapted to grip generally cylindrically-shaped piles of wood and/or concrete. 
     BACKGROUND OF THE INVENTION 
     In the construction industry, it is often necessary to insert piles into and withdraw piles from the earth. A common scenario is the removal of wooden piles and the replacement of these wooden piles with concrete piles. 
     To insert piles into and remove piles from the earth, a large driving or pulling force must be applied to the pile. Often, vibratory devices are employed to introduce a vibratory force along the axis of the pile during the process of driving or pulling the pile. The combination of a static pulling or driving force with a vibratory or dynamic force is usually sufficient to overcome the earth&#39;s resistance and allow the pile to be inserted or withdrawn. 
     In cases where the pile is being withdrawn from the earth and/or a vibratory force is being applied, a clamping assembly must be provided to allow a pulling force and/or vibratory forces to be effectively transmitted to the pile. Such clamping devices have heretofore comprised a housing that is attached to a vibratory hammer which in turn is suspended from a crane line and/or vibratory device, a first gripping surface securely attached to the housing, a second gripping surface connected to a pivot arm that is rotatably attached to the housing, and a piston actuator that acts on the pivot arm to force the second gripping surface against the first gripping surface. 
     Accordingly, to connect a pile to a vibratory device or tensioning cable, the piston actuator is retracted to create a gap between the first and second gripping surfaces. The pile is then inserted between the first and second gripping surfaces and the piston actuator extended such that the pile is gripped between the first and second gripping surfaces. The pile is thus fixed relative to the housing, and the housing itself can be attached to the vibratory device or tensioning cable. 
     Users have experienced a variety of problems with such prior art clamping assemblies. For example, because piles, especially wooden piles, are often of irregular shapes and sizes, the gripping surfaces do not engage certain of these piles in a manner that effectively transmits tensioning or vibratory loads thereto. This allows the pile to slip within the clamping assembly. This is especially true when the piles are coated with barnacles or other materials that reduce friction between the gripping surfaces and the pile. 
     Slippage of the pile relative to the clamping assembly lessens the effectiveness of the clamping assembly at transmitting loads to the pile. Further, during insertion of the pile, such slippage can result in the pile moving upward relative to the clamping assembly housing and contacting an upper wall of this housing. Then, as further driving and/or vibratory forces are applied to the pile, the pile batters the upper wall of the housing. This can cause damage to the clamping assembly housing itself, to the assembly by which the housing is attached to the vibratory device or tensioning cable, and to the machined surfaces on the vibratory device. 
     Another problem with the prior art clamping assemblies is that bolts used to attach the housing thereof to a vibratory device must be installed from within the housing. This is an awkward and time consuming process and exposes the mounting bolts to the impact of the pile. 
     Yet another problem with prior art clamping assemblies is that, because different gripping surfaces are required for different types of piles, a different clamping assembly is required for each of the types of piles that will be driven or pulled. This is especially a problem in cases where wooden piles are being removed and replaced with more permanent piles such as concrete or steel. In this situation, the entire clamping assembly must be removed from the vibratory device between the removal of one pile and the insertion of another. 
     From the following discussion, it will be apparent that these and other problems with prior art clamping assemblies are solved by the present invention. 
     PRIOR ART 
     The Applicant is aware of the following clamp assemblies for connecting pulling and vibratory devices to a pile to be inserted or extracted. 
     International Construction Equipment has for several years sold products identified as a Model 70 Pile Clamp and a Model 50 Pile Clamp. Both of these pile clamps have one fixed jaw and one movable jaw. In the Model 70 Pile Clamp, the actuator and pivot point of the movable jaw are arranged on the same side of the pile. With the Model 50 Pile Clamp, the actuator and pivot point of the movable jaw are arranged on opposite sides of the pile. 
     The Assignee of the present application is also the assignee of U.S. Pat. No. 5,609,380. The &#39;380 patent discloses a clamp assembly having a fixed jaw and a movable jaw. An actuator is operatively connected to the movable jaw such that extension of the actuator causes the movable jaw to move towards the fixed jaw. In the device described in the &#39;380 patent, the movable jaw is pivotably connected to the housing at a pivot point that is arranged on an opposite side of the pile than the side on which the movable jaw is arranged. This arrangement allows the device to be more compact and allows the center of gravity of the clamp assembly to be more aligned with the longitudinal axis of the pile. 
     U.S. Pat. No. 3,998,063 discloses a pile driving/pulling system comprising one fixed shoe and one movable shoe for gripping the pile. 
     U.S. Pat. No. 4,195,698 discloses a driving/pulling system having fixed teeth and movable holding teeth formed on a movable holding teeth member. 
     U.S. Pat. No. 4,180,047 discloses a pile cutting apparatus and system that comprises gripping clamp means for gripping a pile at locations above and below the cut. Eight of these gripping clamp means are located above the cut line. Each of these upper gripping clamp means comprises a dog with gripping teeth formed thereon. The dogs are rotatably connected to a structural member such that the operation of a hydraulic ram forces the gripping teeth against the pile being cut. 
     U.S. Pat. No. 4,018,290 discloses a hydraulically driven vibrator for driving and/or extracting sheet piles having a pair of clamping jaws. One of these clamping jaws is fixed, and the other is connected to an actuator and pivotably attached to the vibrator housing. Operation of the actuator causes the movable jaw to move towards the fixed jaw to clamp the sheet pile. 
     U.S. Pat. No. 4,099,387 to Frederick et al. appears to disclose a clamp for driving sheet piles having one fixed jaw portion and a movable jaw or piston that grips the pile against the fixed jaw portion. 
     U.S. Pat. No. 3,243,190 discloses a vibratory pile driver having a clamp assembly comprising one fixed and one movable jaw. 
     U.S. Pat. No. 3,243,190 discloses a vibratory pile-driver having a clamp assembly composing one fixed-and-on movable jaw. 
     U.S. Pat. No. 4,248,550 discloses a clamping mechanism for extracting piles that uses opposing, movable gripping members connected to the clamp housing. The gripping members are connected to a housing using a parallelogram linkage that causes the gripping members to engage the pile when the housing is lifted and disengage the pile when the housing is dropped. 
     U.S. Pat. No. 3,828,864 discloses a vibratory pile extractor having first and second jaw members. The jaw members receive the pile, and a piston actuator is operated to force the pile against one of the jaw members. 
     U.S. Pat. No. 5,263,544 to White discloses a shock absorbing apparatus, or suppressor, for use with vibratory pile drivers/extractors. 
     European Patent Application No. 89830412.6 discloses a vibratory device for drilling machines comprising a double vice arrangement for clamping the vibratory device to the drilling machine. 
     OBJECTS OF THE INVENTION 
     From the foregoing, it should be clear that one primary object of the present invention is to provide improved clamping systems and methods for securely attaching a pile to a vibratory device or the like. 
     A further object of the invention is to provide a clamp assembly having a favorable combination of the following characteristics: 
     (a) allows vibratory forces to be applied substantially along the longitudinal axis of the pile being driven/extracted; 
     (b) reduces slippage of the pile relative to the clamp assembly; 
     (c) improved pile driving ability; 
     (d) reduction of damage to clamp assembly, connecting assembly, and vibratory device should slippage of the pile relative to the clamp assembly occur; 
     (e) easier attachment of the clamp assembly to the vibratory device; 
     (f) allows a quick and easy change from gripping one pile type to gripping another pile type; and 
     (g) allows the operator of the pile driving and/or pulling equipment to view the operation of the gripping assembly and the activities of workers on the other side of the pile. 
     As will become clear from the following detailed discussion, these and other objects are achieved by the pile clamp system of the present invention. 
     SUMMARY OF THE INVENTION 
     The present invention is a clamping assembly for use in a pile driving and/or removing system that allows a vibratory device to be securely affixed to a pile. The clamping assembly comprises first and second gripping assemblies arranged on either side of the pile. Each gripping assembly is mounted on a pivot arm assembly such that rotation of the pivot arm assembly relative to a housing of the clamp assembly causes the gripping assemblies to engage the pile. Actuator assemblies are rotatably connected to the housing and the pivot arm assemblies such that extension and retraction of the actuator assemblies cause the gripping assemblies to move between an open configuration and a close configuration. 
     The gripping assemblies, pivot arm assemblies, and actuator assemblies are substantially the same and arranged on opposing sides of the pile such that a center of gravity of the clamping assembly is aligned with a center of gravity of the pile. 
     In addition, the movement of the gripping assemblies is coordinated such that these gripping assemblies move between the open and close configurations in synchrony with each other. This may be obtained by synchronizing the action of the actuator assemblies used to move the pivot arm assemblies. Preferably, however, this synchronization is obtained by the use of gear members operatively connected to the gripping assemblies. These gear members extend on either side of the pile and engage each other such that synchronized movement of the gripping assemblies is mechanically obtained. The gear members are also symmetrically arranged about the longitudinal axis of the pile to ensure that the center of gravity of the clamping assembly is substantially aligned with the longitudinal axis of the pile being clamped. 
     The gear members have teeth formed thereon in first and second sets that are offset from each other such that the angular displacement of the pivot arm assemblies relative to horizontal is always the same. The teeth on the gear members extend through an arc of approximately 75 degrees in a circle centered on the longitudinal axis of pivot pins used to attach the pivot arm assemblies to the housing. 
     The housing is a rigid structure having an upper wall connected to a mounting plate by a vertical plate and a plurality of bracing plates. The top wall, vertical plate, bracing plates, and mounting plate form an anvil that engages and drives the pile should slippage between the pile and gripping assemblies occur. 
     The housing is configured such that pivot and hinge pins used to attach the pivot arm assemblies and actuator assemblies to the housing are accessible at all times. In addition, openings are formed in the housing such that actuator pins that connect the actuator assemblies to the pivot arm assemblies are accessible when the gripping assemblies are in their open configuration. Similarly, additional openings are formed in the housing such that actuator pins that connect the actuator assemblies to the pivot arm assemblies are accessible when the gripping assemblies are in their closed configuration. The entire clamping assembly thus may be easily assembled and disassembled for manufacture, repair, and maintenance. 
     The clamping assembly of the present invention obtains the objects described above as well as other objects as will become apparent from a review of the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a somewhat schematic elevational view depicting a pile driving system employing a clamp assembly constructed in accordance with, and embodying, the principles of the present invention; 
     FIG. 2 is a front elevational view showing the clamping assembly in FIG. 1 in more detail when engaged with the pile; 
     FIG. 3 is a side elevational view depicting access openings formed in the housing of the clamp assembly; 
     FIG. 4 is a front elevational view of the clamp assembly with a front panel of the clamp housing removed; 
     FIG. 5 is a top plan view of the clamp assembly  20 ; 
     FIG. 6 is a section view taken along lines  6 — 6  in FIG. 4; 
     FIG. 7 is a section view taken along lines  7 — 7  in FIG. 4; 
     FIG. 8 is a front elevational view similar to that of FIG. 4 depicting the gripping assemblies in an open configuration. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, depicted at  20  therein is a clamp assembly constructed in accordance with, and embodying, the principles of the present invention. This clamp assembly  20  is shown being used as part of a pile driving system  22  that is being used to drive a pile  24  into the ground  26 . The pile driving system  22  is generally conventional and will not be described in detail herein. This system  22  basically comprises a crane assembly  30 , a suppressor assembly  32 , and a vibrator assembly  34 . The suppressor assembly  32  is connected between a main cable  36  of the crane assembly  30  and the vibrator assembly  34 . The vibrator assembly  34  is in turn rigidly connected to the clamp assembly  20 . As will be described in detail below, the clamp assembly  20  engages the pile  24  such that the pile  24  is secured to the vibrator assembly  34 . 
     In use, the pile driving system  22  may be used either to drive piles (as shown in FIG. 1) or to extract piles. When driving piles, the main cable  36  supports the clamp assembly  20 , pile  24 , suppressor assembly  32 , and vibrator assembly  34  such that the pile  24  is held at a desired location  38  at a slight angle. Most of the weight of the clamp assembly  20 , pile  24 , suppressor  32 , and vibrator assembly  34  is supported by the pile  24 . Accordingly, when the vibrator assembly  34  operates, the combination of the static forces of the weight carried by the pile  24  and the vibratory forces generated by the vibrator assembly  34  will cause the pile  24  to be driven into the ground  26  at the desired location  38 . The operator will allow the effective length of the main cable  36  to increase as the pile is driven into the earth  26 . The suppressor assembly  32  inhibits transmission of vibratory forces from the vibrator assembly  34  to the main cable  36 . 
     During extraction of a pile, the situation is similar to that shown in FIG.  1 . When extracting a pile, however, a relatively large tensioning load is applied to the suppressor assembly  32  through the main cable  36 . Accordingly, when the vibratory assembly  34  is operated, the combination of the static tensioning load and the vibratory forces cause the pile to be withdrawn from the earth  26 . 
     The crane assembly  30 , suppressor assembly  32 , vibratory assembly  34 , and main cable  36  are all conventional and will not be described in detail herein. 
     Referring now to FIG. 2, the clamp assembly  20  will be described in further detail. The clamp assembly  20  comprises a housing  50 , first and second pivot assemblies  52  and  54 , first and second gripping assemblies  56  and  58 , and first and second actuator assemblies  60  and  62  (FIG.  4 ). 
     The pivot assemblies  52  and  54  each comprise a pivot arm assembly  70 ,  72  and a pivot pin  74 ,  76 . The pivot pins  74 ,  76  rotatably attach the pivot arm assemblies  70 ,  72  to pivot flanges  78 ,  80 , and  82 ,  84  (FIGS.  4  and  6 ). The pivot flanges  78 - 84  are bearing blocks on which the pivot pins  74 ,  76  are securely supported relative to the housing  50 . Flange holes  86  are formed in the pivot flanges  78 - 84 . 
     The pivot arm assemblies  70  and  72  comprise arm members  90 ,  92 , and  94 ,  96 . Bridge members  100  and  102  extend between the arm members  90 ,  92  and  94 ,  96 , respectively. Spacing blocks  104  and  106  are mounted on the bridge members  100  and  102 , and spacing holes  108  and  110  are formed in the spacing blocks  104  and  106 . Gear members  120 ,  122  and  124 ,  126  are attached to the arm members  90 ,  92 , and  94 ,  96 . 
     While the pivot arm assemblies  70 ,  72  may be cast as a single part, these are preferably formed by welding the arm members  90 - 96 , bridge members  100  and  102 , spacing blocks  104  and  106 , and gear members  120 - 126  together. The main structure of the pivot arm assemblies is formed by the connection of the arm members  90 - 96  with the bridge members  100  and  102 . The spacing blocks allow the actuator assemblies  60  and  62  to be connected to the pivot arm assemblies  70  and  72  as will be described in further detail below. The gear members  120 - 126  are rigidly connected to the arm members  90 - 96 . 
     The gear members  120 - 126  comprise, as perhaps best shown in FIGS. 4 and 8, teeth  130 . The teeth  130  on the gear members  120  and  122  are arranged in a first set  132 . The teeth  130  on the gear members  124  and  126  are arranged in a second set  134 . The teeth  130  are configured and the sets of teeth  132  and  134  are offset from each other such that the teeth  130  engage each other and the arm members  90  and  92  are parallel to the arm members  94  and  96  when the actuator assemblies  60  and  62  are fully extended. By retracting the actuator assemblies  60  and  62  as shown in FIG. 8, the pivot arm assemblies  70  and  72  are moved upward in synchrony with each other such that the inside angles of the arm members  90  and  92  are the same as the inside angles of the arm members  94  and  96  with respect to horizontal. 
     Referring again to FIGS. 4 and 6, it can be seen that a plurality of holes are formed in the pivot arm assemblies  70  and  72 . In particular, a grip hole  140 , an actuator hole  142 , and a pivot hole  144  are formed in each of the arm members  90 - 96 . A gear grip hole  146  and a gear actuator hole  148  are formed in each of the gear members  120 - 126 . The grip holes  140  are aligned with each other and the gear grip holes  146  along a common axis. Similarly, the actuator holes  142  and the gear actuator, holes  148  are aligned with each other and along a common axis. The pivot pins  74  and  76  extend through the flange holes  86  formed in the pivot flanges  78 - 84  and the pivot holes  144  formed in the arm members  90 - 96  such that the pivot arm assemblies  70  and  72  pivot about axes defined by the pivot pins  74  and  76 . 
     Referring for a moment again to the first and second sets  132  and  134  of teeth  130 , it can be seen that these sets  132  and  134  lie along circles centered at the axes of the pivot pins  74  and  76 . In particular, these sets of teeth  132  and  134  lie in an arc defined by an angle of approximately 75 degrees. 
     Referring now to FIGS. 6 and 7, depicted therein in detail are the gripping assemblies  56  and  58 . These gripping assemblies are identical and each comprises a gripping member  150  and a gripping pin  152 . Gripping ribs  154  are formed on the gripping member  150  and a slightly concave gripping surface  156  is defined on the gripping member  150  where this member is intended to engage the pile  24 . It should be noted that the gripping surface  156  and the gripping ribs  154  will be designed to accommodate a pile of a given cross-sectional area and material. For example, to drive or remove a wooden pile, the ribs  154  will be relatively sharper and the gripping surface  156  will be curved so that it closely approximates the outer surface of the piles being driven or pulled. For a concrete pile, the ribs will be smaller or perhaps even eliminated to provide greater surface area for engagement with the pile and thus increased friction to reduce slippage. 
     Referring still to FIG. 7, the actuator assemblies  60  and  62  will now be described in further detail. These assemblies  60  and  62  are identical, and only the actuator assembly  60  will be described in detail with the understanding that this description applies to the other actuator assembly  62 . 
     The actuator assembly  60  comprises an actuator cylinder  170  and an actuator shaft  174 . The shaft  174  reciprocates within the cylinder  170  to increase or decrease the effective length of the actuator assembly  60 . The cylinder  170  will preferably be a hydraulic cylinder with a piston head attached to the shaft  174  such that introduction of hydraulic fluid on either side of the piston head within the cylinder  170  causes appropriate movement of the shaft  174 . Such assemblies are well known and will not be described in detail herein. 
     Rigidly extending from the cylinder  170  are a pair of hinge flanges  174 . A hinge pin  176  extending through the hinge flanges  174  rotatably attaches the actuator assembly  60  to the housing  50 . A pair of shaft flanges  178  extend from the shaft  174 . An actuator pin  180  extends through the shaft flanges  178  and the spacing holes  108  and  110  in the spacing blocks  104  and  106 . The actuator pins  180  thus rotatably attach the actuator assemblies  60  and  62  to the pivot arm assemblies  70  and  72 . 
     The housing  50  will now be described in detail. The housing  50  is a rigid structure that performs two main purposes. First, it allows the clamp assembly  20  to be connected to the vibratory device  34  as described above. Second, it forms a rigid structure that spaces the pivot pins  74  and  76  and hinge pins  176  in a predetermined relationship to one another. In addition, the housing  50  encloses moving parts and is perforated at strategic locations to allow disassembly and maintenance of the moving parts contained therein. 
     The housing  50  is a hollow, generally rectangular body comprising a front wall  200 , a back wall  202 , end walls  204  and  206 , a top wall  208 , and a bottom wall  210 . A mounting plate  212  is spaced above the top wall  208  by a vertical plate  214  and a plurality of bracing plates  216 . A plurality of mounting holes  218  are formed in the mounting plate  212 . The bracing plates  216  are spaced from each other so that access to the mounting holes  218  is unhindered. 
     Mounted below the bottom wall  210  is an alignment plate  220  in which an alignment opening  222  is formed. The bottom plate  210  and alignment plate  220  are attached to the front and back walls  200  and  202  by bolt assemblies  224 . 
     Bolt assemblies  226  are used to attach the mounting plate  212  to the vibrator assembly  34 , only a position of which is shown in FIGS. 2,  4 , and  8 . 
     Referring to FIG. 3, access openings  230  are formed in the end walls  204  and  206  to allow access to set screws  232  that fix the pivot pins  74  and  76  relative to the arm members  90 ,  92 , and  94 ,  96 . 
     As shown in FIG. 8, a pile area  240  is defined within the clamp assembly  20 . The clamp assembly  20  is symmetrically arranged about this pile area  240  such that a center of gravity of the clamp assembly  20  extends through the middle of the pile area  240 . Accordingly, when the pile  24  is engaged with the clamp assembly  20  as shown in FIG. 2, the longitudinal axis of the pile  24  is substantially aligned with the center of gravity of the clamp assembly  20 . Accordingly, when the driving/pulling forces and vibratory forces are applied to the clamp assembly  20 , the clamp assembly  20  symmetrically applies these forces to the pile  24  in a manner that does not create a bending moment in the pile  24  under normal conditions. 
     As described above, the actuator assemblies  60  and  62  extend and retract such that the gripping assemblies  56  and  58  move between a fully open position as shown in FIG. 8 and a fully closed position as shown in FIG.  4 . The clamp assemblies  56  and  58  are spaced farthest from each other in the open position and closest to each other in the closed position. To engage a pile, the actuator assemblies  60  and  62  are shortened to place the gripping assemblies  56  and  58  in their open configuration. The pile is then passed through the alignment opening  222  into the pile area  240 . The actuators are then extended such that the gripping assemblies  56  and  58  move towards each other until the pile  24  is securely gripped therebetween as shown in FIG.  2 . 
     The gear members  120 ,  122 , and  124 ,  126  engage each other as the gripping assemblies  56  and  58  move between the open and close configurations so that these gripping assemblies  56  and  58  move in synchrony with each other. This ensures that the longitudinal axis of the pile  24  is as close as possible to the center of gravity of the clamping assembly  20 . 
     In addition, when the pile  24  is clamped as shown in FIG. 2, the gear members  120 - 126  engage each other to rigidify the entire clamp assembly  20 . This will reduce lateral movement or vibration of the housing  50  relative to the pile  24  when vibratory loads are being transmitted through the clamping assembly  20 . 
     The housing  50  is configured with a plurality of access openings including an upper access opening  250  and first and second lower access openings  252  and  254 . When the clamping assemblies are in their open configuration as shown in FIG. 8, the gripping pins  152  may be accessed through the upper access opening  250  to allow these pins  152  to be removed and inserted to facilitate changing of the gripping assemblies  56  and  58 . When the gripping assemblies  56  and  58  are in their closed position as shown in FIG. 4, the actuator pins  180  may be accessed through the lower access openings  252  and  254 . This facilitates disassembly of the pivot arm assembly  70  and  72  from the actuator assemblies  60  and  62  for repair and maintenance. 
     And as shown in FIG. 2, the pivot pins  74  and  76  and hinge pins  176  are accessible from outside of the housing  50  to facilitate removal of these pins  74 ,  76 , and  176  for repair and maintenance of the clamping assembly  20 . 
     From the foregoing, it should be apparent that the present invention may be embodied in forms other than that described above. The scope of the invention should thus be determined by the claims appended hereto and not the foregoing detailed description.