Patent Publication Number: US-8967217-B2

Title: Hand-held strapper

Description:
CROSS-REFERENCE TO RELATED APPLICATION DATA 
     This application claims the benefit of priority of Provisional U.S. Patent Application Ser. No. 61/445,404, filed Feb. 22, 2011, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     Strapping tools or strappers come in a wide variety of types, from completely manual tools to automatic, table-top tools. Strapping tools can be designed and intended for use with different types of strap or strapping materials, such as metal strapping or plastic/polymeric strapping. Strappers for applying plastic or polymeric strapping materials are typically automatic table-top or hand-held devices that are powered to adhere the strap onto itself. The adhering function can be performed by melting or otherwise welding a section of the strap onto itself utilizing ultrasonic or vibrational-type weld assemblies. Such weld assemblies can be powered by electrical, electromechanical, and/or fluid drive (hydraulic or pneumatic) systems. 
     One known tool disclosed in Nix U.S. Pat. No. 6,907,717, which is incorporated by reference herein, is powered by a pneumatic system that includes first and second pneumatic motors. In the present example, the first pneumatic motor is operatively coupled to a tensioning assembly and the second pneumatic motor is operatively coupled to a weld assembly. Generally, the tensioning assembly includes a feed wheel operatively coupled to the first motor and an anvil foot. The feed wheel and anvil foot are manually separated by a user pulling a housing of the first pneumatic motor upwardly toward a grip. With the feed wheel and anvil foot separated, overlapping strap portions are inserted between the feed wheel and the anvil foot and the housing of the first motor can be released to clamp the strap portions. Thereafter, the first motor can be actuated to rotate the feed wheel and tension the strap. Further, the weld assembly generally includes a weld element operatively coupled to the second motor and a stationary weld pad. Once the strap has been tensioned, the second motor is actuated to vibrate the weld element and seal the overlapping strap portions together. 
     While the multiple motor tool described generally above has proved to be effective and reliable, there exists a desire for an improved tool that is reliably, easily, and comfortably hand-operated by a user. 
     SUMMARY 
     Various embodiments of the present disclosure provide a strapping tool for tensioning and securing a strap on or around an object or load that includes a motor, a tensioning assembly coupled to the motor, and a weld plate assembly coupled to the motor. The motor is actuated in a first direction to control the tensioning assembly to tension the strap during a tensioning operation and the motor is actuated in a second direction to control the weld plate assembly to weld the strap to itself during a welding operation. 
     Other embodiments of the present disclosure provide a strapping tool that includes a motor, a tensioning assembly coupled to the motor, and an opening assembly coupled to the tensioning assembly. The motor actuates the tensioning assembly to tension overlapping strap portions clamped by the tensioning assembly during a tensioning operation and the opening assembly is actuated to unclamp the overlapping strap portions during a powered opening operation. 
     Still other embodiments of the present disclosure provide a strapping tool for tensioning and securing a strap that includes a motor, a weld plate assembly coupled to the motor, a tensioning assembly coupled to the motor, an opening assembly coupled to the tensioning assembly, and a pneumatic system coupled to the motor, the weld plate assembly, the tensioning assembly, and the opening assembly. The motor controls the weld plate assembly to weld the strap to itself during a welding operation and the motor controls the tensioning assembly to tension the strap during a tensioning operation. The opening assembly is actuated to unclamp the overlapping strap portions during a powered opening operation. The pneumatic system further includes a compressed gas inlet to the system, a tension pilot valve for controlling a flow of compressed gas to actuate the motor in a first direction during the tensioning operation, a weld pilot valve for controlling a flow of compressed gas to actuate the motor in a second direction and to actuate a piston that forces an upper weld gripper against a lower weld gripper during the welding operation, and an opening valve for controlling a flow of compressed gas to the opening assembly during the powered opening operation. 
     In this manner, the present disclosure provides an enhanced tool that is reliably, easily, and comfortably hand-operated by a user. Such an improved tool is generally more compact and ergonomic than prior tools and, in one embodiment, may provide a mechanism for unclamping the tool from strapping in a powered operation, as opposed to manually unclamping the tool with a hand operated lever. Further, the tool may include one or more features for preventing operation of the tensioning and weld functions out of order and for minimizing strap jam-up issues. 
     Other objects, features, and advantages of the disclosure will be apparent from the following description, taken in conjunction with the accompanying sheets of drawings, wherein like numerals refer to like parts, elements, components, steps, and processes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a strapping tool in accordance with an embodiment of the present disclosure; 
         FIG. 2  is a left-side elevational view of the strapping tool of  FIG. 1 ; 
         FIG. 3  illustrates the tool of  FIG. 1  positioned relative to a load being strapped; 
         FIG. 4  is an exploded view of the strapping tool of  FIG. 1 ; 
         FIG. 5  is an enlarged left-side elevational view similar to  FIG. 2  with portions of the strapping tool removed to illustrate an opening assembly in a first position; 
         FIG. 6  is an enlarged left-side elevational view similar to  FIG. 5  with the opening assembly in a second position; 
         FIG. 7  is an enlarged exploded view of a feed wheel drive gear assembly and a weld plate drive gear assembly of the tool of  FIG. 1 ; and 
         FIG. 8  is a pneumatic circuit diagram of a strapping tool, such as the tool of  FIG. 1 , in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     While the present disclosure is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described one or more embodiments with the understanding that the present disclosure is to be considered illustrative only and is not intended to limit the disclosure to any specific embodiment described or illustrated. 
     Referring now to  FIGS. 1-7 , a strapper or strapping tool  20  in accordance with an embodiment of the present disclosure is shown. The illustrated strapper or strapping tool  20  (sometimes referred to herein as “tool” for brevity) is configured to tension a strap or strapping material  22  around an object or load  24 , weld overlapping portions of the strap  22  together, and sever or cut the strap. Generally, the strap  22  includes a feed or supply end  26  and a free end  28  that is fed around the load  24  and reinserted into the tool  20  to overlap the feed end. 
     The tool  20  includes a motor module assembly  30  operatively coupled to a head assembly  32 . The motor module assembly  30  includes a connection  34  for a compressed or pressurized fluid source to drive a motor  36 . In one embodiment, the motor  36  is a single reversible air or gas driven motor, the function of which will be described in more detail hereinafter. However, in other examples, the motor  36  can be driven by any other type of hydraulic fluid or may be an electrically driven motor. The motor module assembly  30  includes a mechanism  38  that can be adjusted to change the length of a weld time. In accordance with one example, the mechanism  38  can be an adjustable screw that can be turned by hand or with a screwdriver, for example, to adjust the weld time. Further, the motor module assembly  30  includes a grip  40  for a user to hold the tool  20  and actuate an opening switch  42 , a tensioning switch  44 , and a welding switch  46 . 
     The opening switch  42  is arranged on a bottom portion  48  of the grip  40  such that when a user grasps the grip with an overhand grip, the opening switch is positioned generally proximate the user&#39;s index finger and can be actuated similarly to pulling a trigger, as would be understood by one of ordinary skill. The tensioning switch  44  and the welding switch  46  are arranged on an upper portion  50  of the grip  40  such that when the user grasps the grip, the tensioning and welding switches are positioned generally proximate the user&#39;s thumb. 
     The motor module assembly  30  also includes a weld switch lockout assembly  60  coupled thereto. The weld switch lockout assembly  60  is actuated to prevent the welding switch  46  from being depressed out of order with the opening switch  42  and the tensioning switch  44 . In accordance with the present example, the weld switch lockout assembly  60  includes a weld lockout piston  62  disposed within a lockout cylinder  64 . The weld lockout piston  62  is extended and retracted from the lockout cylinder  64  to prevent and allow, respectively, the welding switch  46  from being depressed, as will be described in more detail hereinafter. Interference or seal members  66 , such as o-rings, are disposed on the weld lockout piston  62  and interact with the lockout cylinder  64  to hold the piston in place when the piston is extended and retracted. 
     The head assembly  32  of the tool  20  includes a gripper housing assembly  70  and a tensioning assembly  72  mounted to the gripper housing assembly. The tensioning assembly  72  includes a tensioner foot assembly  74  and a feed wheel  76 . The tensioner foot assembly  74  is pivotally mounted about a pivot pin  78  to the gripper housing assembly  70  so that the foot assembly  74  can pivot toward and away from the feed wheel  76 . A biasing element  80 , such as a torsion spring, is further disposed over the pivot pin  78  and is configured to bias the tensioner foot assembly  74  in a first position against the feed wheel  76 , as shown generally in  FIG. 5 . More particularly, the tensioner foot assembly  74  includes a gripper plug  82  that is biased against the feed wheel  76  by the biasing element  80  in the first position. 
     The feed wheel  76  is rotatably mounted to the gripper housing assembly  70  and is operatively coupled to a feed wheel drive gear assembly  84 . The feed wheel drive gear assembly  84  is further operatively coupled to the motor  36 , which is actuated in a first direction, for example, a clockwise direction, to rotate the gear assembly  84  and the feed wheel  76 . In accordance with one example, when overlapping portions of strap  22  are clamped between the gripper plug  82  and the feed wheel  76  and the motor  36  is actuated in the first direction, the feed wheel rotates and tensions the strap by driving the feed end  26  of the strap in the direction indicated by an arrow  86  in  FIG. 3 . 
     The illustrated tool  20  also includes a mechanism  88  that can be adjusted to change the maximum tension drawn by the feed wheel  76 . In accordance with one example, the mechanism  88  can be an adjustable screw that can be turned by hand or with a screwdriver, for example, to adjust the size of a compressed gas flow passage to the motor  36  and, thus, to adjust the revolutions-per-minute of the motor and a stall out tension of the feed wheel  76 . 
     In accordance with the present example, the tool  20  also includes an opening assembly or mechanism  90  that performs a powered opening operation when the opening switch  42  is depressed. The opening assembly  90  is shown more clearly in  FIGS. 4-6  and includes a foot lever  92  coupled to the tensioner foot assembly  74 , such as at the pivot pin  78 . When the tensioner foot assembly  74  is in a first position or stage, as seen in  FIG. 5 , the foot lever  92  has a proximate portion  94  that extends generally horizontally away from the lever and a distal portion  96  that extends generally angularly away from the proximate portion. In the present example, the distal portion  96  curves upwardly away from the proximate portion  94 . Alternatively, the distal portion  96  may extend linearly, angularly away from the proximate portion  94 . 
     The opening assembly  90  is actuated by movement of a first piston  100  disposed within a first piston chamber  102  coupled to the gear housing assembly  70 . In the present example, a first piston rod  104  with an inclined plane member  106  is coupled to the first piston  100 , such that actuation of the first piston downwardly in the first piston chamber  102  drives the first piston rod downwardly from the first position, as seen in  FIG. 5 , to a second position or stage, as seen in  FIG. 6 . An extension spring  108  disposed between the piston rod  104  and the first piston  100  biases the piston rod and piston upwardly to the first position. 
     In one example of the opening assembly  90  in use, the first piston  100  is driven downwardly, such as by routing compressed gas into the first piston chamber  102 . The downward movement of the first piston  100  engages and drives the inclined plane member  106  of the piston rod  104  downward. The inclined plane member  106  contacts the distal portion  96  of the foot lever  92  in the first position, as shown in  FIG. 5 , and exerts a maximum opening force to push the tensioner foot assembly  74  and the gripper plug  82  away from the feed wheel  76 . The first piston  100  is further driven downward so that the inclined plane member  106  of the piston rod  104  contacts the proximate portion  94  of the foot lever  92 , as shown in  FIG. 6 , to rotate the tensioner foot assembly  74  and the gripper plug  82  away from the feed wheel  76  and provide maximum clearance for inserting and removing the strap  22 . 
     The head assembly  32  further includes a weld plate assembly  110  mounted to the gripper housing assembly  70 . The weld plate assembly  110  includes a lower weld gripper  112  and an upper weld gripper  114 . In the present example, the weld plate assembly  110  includes a foot  116  and the lower weld gripper  112  is held stationary with respect to the weld plate assembly  110  on the foot. The upper weld gripper  114  is coupled to a linkage arm  118 , such as by a pivot pin  120 , and the linkage arm is operatively coupled to a weld plate drive gear assembly  122 . In the present example, the weld plate drive gear assembly  122  includes an eccentric shaft  124  that is disposed within a generally circular opening  126  defined in the linkage arm  118 . The weld plate drive gear assembly  122  is further operatively coupled to the motor  36 , which is actuated to rotate the weld plate drive gear assembly. Rotation of the weld plate drive gear assembly  122  causes the eccentric shaft  124  to rotate within the circular opening  126  in the linkage arm  118 , thereby causing an oscillating vibration of the upper weld gripper  114 . 
     In one example, actuation of the motor  36  in the first direction (e.g., the clockwise direction) or in a second direction (e.g., a counterclockwise direction) causes the weld plate drive gear assembly  122  and the eccentric shaft  124  to rotate, thereby causing the upper weld gripper  114  to vibrate. However, the weld operation is only performed when the upper weld gripper  114  is vibrating and being forced against the lower weld gripper  112 . 
     In accordance with the illustrated embodiment, the weld plate assembly  110  includes a second piston  130  disposed within a second piston chamber  132 , wherein the second piston is actuated to force the upper weld gripper  114  against the lower weld gripper  112 . More particularly, a second piston rod  134  is coupled to the second piston  132 , such that actuation of the second piston drives the second piston rod downwardly against the linkage arm  118  to force the upper weld gripper  114  against the lower weld gripper  112 . The force of the upper weld gripper  114  against the lower weld gripper  112  and the vibration of the upper weld gripper welds overlapping portions of strap  22  together. A biasing element  136 , such as a spring, is further disposed within the second piston chamber  130  to bias the second piston  132  and the piston rod  134  away from the linkage arm  118  until the second piston is actuated to perform the weld operation. In one example, the actuation of the second piston  132  to force the upper weld gripper  114  against the lower gripper  112  corresponds with the actuation of the motor  36  in the second direction, for example the counterclockwise direction, to perform the weld operation. 
     In addition, a cutting assembly  140  is coupled to the weld plate assembly  110  to cut the strap  22 . More particularly, the cutting assembly  140  includes a contact plate  142  coupled to a cutter insert holder  144 . A cutter  146  is further coupled to the cutter insert holder  144  and the contact plate  142  is mounted to the second piston  132  to move downwardly onto the feed end  26  of the strap  22  along with the linkage arm  118  and the upper weld gripper  114 . The cutting assembly  140  includes a spring  148  so that the cutter  146  is allowed to float within the cutter insert holder  144  to assure that the top feed end  26  of the strap  22  is cut and the free end  28  of the strap is not cut. 
     Referring now to  FIG. 7 , the feed wheel and the weld plate drive gear assemblies  84 ,  122  include various components to allow the motor  36 , which can be a single reversible motor, to drive both assemblies. In the present example, the feed wheel drive gear assembly  84  includes a drive belt  160  coupled to the motor  36 , such as to a drive shaft (not shown) of the motor, as would be apparent to one of ordinary skill in the art. The drive belt  160  is further coupled to a first wheel  162  of a pulley assembly  164 . The motor  36  is actuated to drive the drive belt  160  and rotate the first wheel  162  and a second wheel  166  of the pulley assembly  164 . A roller clutch  168  is disposed within the pulley assembly  164  and is coupled to a drive shaft or pinion  170 , such as a spiroid pinion. When the motor  36  is actuated in the first direction, the drive belt  160  rotates the pulley assembly  164  in the first direction and the roller clutch  168  engages the pinion  170  to rotate same. When the motor  36  is actuated in the second direction, the drive belt  160  rotates the pulley assembly  164  in the second direction but the roller clutch  168  disengages from the pinion  170  and freewheels around the pinion. The pinion  170  is further coupled to rotate the feed wheel  76  to perform the tensioning operation. 
     A brake assembly  180  is further coupled to the feed wheel drive gear assembly  84  to prevent the feed wheel  76  from reversing direction and releasing tension from the clamped strap  22  until the opening switch  42  is depressed. In accordance with the present example, the brake assembly  180  includes a toothed brake wheel  182  coupled to the pinion  170  by a second roller clutch  184 . The second roller clutch  184  engages the pinion  170  when same is rotated in the second direction and disengages from the pinion when same is rotated in the first direction. The brake assembly  180  further includes a pawl assembly  186  that is coupled to the gear housing assembly  70 . In the present example, the pawl assembly  186  includes a pawl  188  disposed on a first end of a brake pin  190  and a brake lever  192  disposed on a second opposing end of the brake pin. A brake spring  194  and a brake roller  196  are further coupled to the brake pin  190 . The brake spring  194  biases the pawl assembly  186  so that the pawl  188  is engaged with the toothed brake wheel  182  to prevent same from rotating in the second direction and allowing tension to be released from the strap  22 . 
     When the opening switch  42  is depressed and the opening assembly  90  actuated, the opening assembly interacts with the pawl assembly  186  to disengage the brake wheel  182  and allow the pinion  170  to rotate in the second direction. The rotation of the pinion  170  in the second direction allows the feed wheel  76  to reverse direction and release tension from the strap  22 , which can then be more easily removed from the strapper  20 . In one example, when the opening assembly  90  is actuated, the first piston rod  104  is driven downward and engages the brake lever  192 , which in turn rotates the pawl  188  out of engagement with the brake wheel  182 . 
     The weld plate drive gear assembly  122  further includes a weld belt  198  that is coupled the second wheel  166  of the pulley assembly  162  and to the eccentric shaft  124 . The motor  36  is actuated in the first or second directions to drive the drive belt  160 , which rotates the pulley assembly  164  and drives the weld belt  198 . Driving the weld belt  198  rotates the eccentric shaft  124  and causes the upper weld gripper  114  to vibrate. In the present example, the upper weld gripper  114  vibrates when the motor  36  is actuated in the first or second directions. However, the vibration of the upper weld gripper  114  does not weld overlapping portions of the strap  22  together until the second piston  130  is actuated to force the upper weld gripper  114  against the lower weld gripper  112 , as described above. 
     The feed wheel and the weld plate drive gear assemblies  84 ,  122  may include fewer or additional components, as would be apparent to one of ordinary skill in the art. For example, the assemblies  84 ,  122  may include various washers, spacers, bearings, retention rings, etc., without departing from the spirit and scope of the present disclosure. 
     Referring now to the pneumatic circuit or module  200  of  FIG. 8 , gas is supplied to the tool  20  through a compressed gas supply  202  and enters a tension pilot valve  204 , which is normally biased in an off or closed position. In the illustrated circuit, the tension pilot valve  204  is configured to supply a continuous flow of gas, regardless of whether the tension pilot valve is off or on, to an opening valve  206  and a weld pilot valve  208 . The tension pilot valve  204  may be any suitable valve, such as a 3 or 4 port and 2 position valve, as would be apparent to one of ordinary skill in the art. The opening valve  206  and the weld pilot valve  208  are both normally biased in off positions, as shown in  FIG. 8 . The opening valve  206  and the weld pilot valve  208  are also shown generally back-to-back in  FIG. 4 . Gas from the compressed gas supply  202  is also routed to a back side  210  of a seal valve  212  and a back side  214  of a tension valve  216  to bias the seal valve and the tension valve in off or closed positions, as shown. 
     Depression or actuation of the opening switch  42  moves the opening valve  206  to an on or open position, which routes gas to the first piston chamber  102  to separate and open the tensioner foot assembly  74  and the gripper plug  82  from the feed wheel  76  so that the strap  22  can be inserted or removed therefrom, as described above. Once the strap  22  is inserted or removed, the opening switch  42  can be released and the opening valve  206  returned to the off position so that gas is no longer routed to the first piston chamber  102  and the biasing element  80  is allowed to bias the tensioner foot assembly  74  and the gripper plug  82  back against the feed wheel  76 . 
     Moving the opening valve  206  to the on position also routes gas to a back side  218  of the weld pilot valve  208  to force the pilot valve to the off position and to ensure that the welding switch  46  is not depressed. Simultaneously therewith, gas is routed to the weld switch lockout assembly  60  to extend the weld lockout piston  62 , which engages and prevents depression of the welding switch  46 . 
     With the strap  22  gripped between the gripper plug  82  and the feed wheel  76 , a user can depress or actuate the tensioning switch  44  to move the tension pilot valve  204  to an on or open position, which routes gas to a front side  220  of the tension valve  216  to move the tension valve to an on position. When the tension valve  216  is in the on position, gas is routed from the gas supply  202  through the tension valve to the motor  36  to actuate the motor in the first direction. The actuation of the motor  36  in the first direction rotates the feed wheel drive gear assembly  84  and causes the feed wheel  76  to rotate and tension the strap  22 . Generally, the strap  22  is being tensioned around a load  24  and the motor  36  will stall out when a maximum amount of tension is drawn by the feed wheel  76 . However, the tension switch  44  may be held down as long as desired and can be released at any time before the maximum tension is drawn. Further, as discussed above, the mechanism  88  can be coupled to the motor  36  to adjust a flow of compressed gas to the motor and, thus, adjust the maximum tension at stall out. 
     Actuation of the tension pilot valve  204  to the on position also routes gas to the weld switch lockout assembly  60  to retract the weld lockout piston  62  and allow the weld switch  46  to be depressed. Consequently, the weld operation cannot be initiated out of order with the tensioning operation. 
     Depression or actuation of the weld switch  46  moves the weld pilot valve  208  to an on or open position, which routes gas to the second piston chamber  132  to force the upper weld gripper  114  against the lower weld gripper  112 . Actuation of the weld pilot valve  208  to the on position also routes gas to a weld shut-off valve  222 . The weld shut-off valve  222  is normally biased in an on or open position so that gas routed thereto is further routed to a front side  224  of the seal valve  212  to move the seal valve to an on or open position. When the seal valve  212  is in the on position, gas is routed from the gas supply  202  to the motor  36  to actuate the motor in the second direction. The actuation of the motor  36  in the second direction rotates the weld plate drive gear assembly  122  and causes the upper weld gripper  114  to vibrate and weld the strap  22 , as discussed above. 
     Actuation of the weld pilot valve  208  to the open position also routes gas to a weld timer valve  226  and a back side  228  of a check valve  230 . In one example, the weld timer valve  226  is a variable orifice valve that regulates a flow rate of gas to a timing chamber or accumulator  232 . The regulated flow of gas through the weld timer valve  226  increases the pressure in the timing chamber  232  over time, thus providing a timing function. Gas from the timing chamber  232  is routed to a front side  234  of the weld shut-off valve  222  as the pressure increases in the timing chamber. When the pressure in the timing chamber  232  reaches a predetermined pressure, the gas routed to the front side  234  of the weld shut-off valve  222  causes the weld shut-off valve to close, thus stopping or isolating the gas flow to the seal valve  212  and stopping rotation of the motor  36  in the second direction and vibration of the upper weld gripper  114 . The mechanism  38 , discussed above, can be coupled to the weld timer valve  226  to adjust the flow rate and, thus, adjust the weld time. 
     In the present example, once the weld switch  46  is depressed and the weld pilot valve  208  moved to the open position, the weld pilot valve remains biased in the open position. The weld pilot valve  208  does not return to the off or closed position until the opening switch  42  is again depressed or actuated. When the opening switch  42  is again depressed, the opening valve  206  is moved to the open position and gas is rotated to the back side  218  of the weld pilot valve  208  to move the weld pilot valve to the closed position. With the weld pilot valve  208  in the closed position, gas is no longer routed to the back side  228  of the check valve  230  and gas is allowed to vent from the timing chamber  232  through the check valve. Thereafter, the opening, tensioning, and welding operations can be repeated, as described above. 
     It should be understood that various changes and modifications to the presently preferred embodiments disclosed herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present disclosure and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.