Abstract:
A tool that installs a metal tie is disclosed. The tool includes a tension mechanism and a tension control system. The tension mechanism tensions the metal tie wrapped around a bundle. The tension control system measures the applied tie tension. The tension control system includes a load cell and a worm cushion that dampens the tension applied to the load cell. The tension mechanism includes a gear train with a worm gear and a worm that distribute the applied tension to the load cell. Once the desired tension has been achieved, the tension mechanism is de-energized and a ball set and cut-off mechanism is activated to set the ball in the metal tie head and to shear a portion of the tensioned metal tie.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a metal tie tool, and more particularly to a metal retained tension tie tool with an electric tension control system. 
     BACKGROUND OF THE INVENTION 
     As is well known to those skilled in the art, cable ties, or straps are used to bundle or secure a group of articles such as electrical wires and cables. Cable ties of conventional construction include a cable tie head and an elongated tail extending therefrom. The tail is wrapped around a bundle of articles and thereafter inserted through the passage in the head. The head of the cable tie typically supports a locking element, which extends into the head passage and engages the body of the tail to secure the tail to the head. 
     In practice, the installer manually places the tie about the articles to be bundled and inserts the tail through the head passage. At this point, a cable tie installation tool is used to tension the tie to a predetermined tension. The tools of the prior art, although capable of tensioning and thereafter severing the excess portion of the cable tie, typically have several disadvantages therewith. As a result, it is desirable to provide a metal tie tool having an improved electric tension control system. It is also desirable to provide a metal tie tool having an improved ball set and cut-off mechanism. 
     SUMMARY OF THE INVENTION 
     A tool that installs a metal tie is disclosed. The tool includes a tension mechanism that tensions a metal tie around a bundle and a tension control system that measures the applied tie tension. The tension control system includes a load cell and a worm cushion that dampens the tension applied to the load cell. The tension mechanism includes a gear train with a worm gear and a worm that distribute the applied tension to the load cell and rotary gripper gears that tension the metal tie. Once the load cell measures the desired applied tie tension, the tension mechanism is de-energized and a ball set and cut-off mechanism is activated to set the ball in the metal tie head and to shear a portion of the tensioned metal tie. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a right side perspective view of the metal retained tension tie tool of the present invention; 
         FIG. 2  is a left side perspective view of the metal retained tension tie tool of  FIG. 1 ; 
         FIG. 3  is a right side perspective view of the metal retained tension tie tool of  FIG. 1  with the cover removed; 
         FIG. 4  is a partial perspective side view of the gripper gears of the metal retained tension tie tool of  FIG. 1 ; 
         FIG. 5  is a partial perspective view of the metal retained tension tie tool of  FIG. 4 ; 
         FIG. 6  is a side view of the metal retained tension tie tool of  FIG. 5 ; 
         FIG. 7  is a side view of the metal retained tension tie tool of  FIG. 5  with the rotary gears meshed; 
         FIG. 8  is a partial side view of the metal retained tension tie tool of  FIG. 2  with the cover removed; 
         FIG. 9  is a partial side view of the metal retained tension tie tool of  FIG. 2  with the gear box cover removed; 
         FIG. 10  is a partial perspective side view of the tension control system of the metal retained tension tie tool of  FIG. 2  with the worm cushion removed; 
         FIG. 11  is a partial perspective side view of the tension control system of  FIG. 10 ; 
         FIG. 12  is a cross sectional view of the tension control system of  FIG. 10 ; 
         FIG. 13  is a partial side view of the ball set and shear mechanism of the metal retained tension tie tool of  FIG. 1 ; 
         FIG. 14  is a side perspective view of the ball set and shear mechanism of the metal retained tension tie tool of  FIG. 1 ; 
         FIG. 15  is a side perspective view of the ball set and shear mechanism of the metal retained tension tie tool of  FIG. 14  with the ball set in the tie head; and 
         FIG. 16  is a side perspective view of the ball set and shear mechanism of the metal retained tension tie tool of  FIG. 14  with the tie tail sheared. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  illustrate a right and left side view, respectively, of the metal retained tension tie tool  50  of the present invention. The metal retained tension tie tool  50  includes rotary gripper gears  70  (see  FIGS. 3-7 ) for tensioning the metal tie  200 , an electric tension control system  100  (see  FIGS. 8-12 ) and a ball set and tie shear mechanism  150  (see  FIGS. 3 ,  4  and  13 - 16 ). The metal retained tension tie tool  50  includes a tie entry  54  and a tie tail exit  56  for releasing the sheared tie tail  202 . 
       FIGS. 3-7  illustrate the rotary gripper gears  70  that tension the metal tie  200 . The rotary gripper gears  70  includes a pancake cylinder  72 , gripper gear toggle links  74 , a gear train  76 , a large gripper gear  90  and an idle gripper gear  92 . A tension motor  58  (see  FIG. 8 ) generates the rotary motion of the gears. The rotary motion is controlled by the gear train  76  that reduces the speed to achieve the torque needed to pull the tie  200 . As discussed below, when the gear toggle links  74  are engaged and the gears rotate, the large gripper gear  90  and the idle gripper gear  92  mesh together to create the pulling force on the tie tail  202 . 
     The gear train  76  includes the intermediate gears  78  illustrated in  FIGS. 3-7  and the worm gear  130  and worm  132  illustrated in  FIGS. 9 ,  10  and  12 . 
       FIGS. 5-7  illustrate the rotary gripper gears  70  tensioning the metal tie  200 . An operator manually places the metal tie  200  around a bundle  210  and then slides the tie tail  202  into the anvil  182  through the open gripper gears  90 ,  92 . Once the trigger  52  is pressed to start the tool, the tension motor  58  is activated. The trigger  52  also drives the intermediate gears  78 , which drive the large gripper gear  90 . The tension motor  58  also activates the pancake cylinder  72  enabling the cylinder  72  to extend, which toggles the gripper toggle links  74 . As shown in  FIG. 7 , the gripper toggle links  74  move forward, forcing the idle gripper gear  92  to engage the large gripper gear  90 . When the gripper gears  90 ,  92  are meshed and rotating, they create the pulling force on the tie tail  202  that causes the tie  200  to tension around the bundle  210 . The large gripper gear  90  and the idle gripper gear  92  include a sine wave profile. As a result, the tie tail  202  becomes deformed as it passes through the meshed gripper gears  90 ,  92 . 
     An electric tension control system  100  controls the tension of the tie  200  around the bundle  210  and signals the system to halt tensioning once the desired tension has been achieved. As described below, once the desired tension has been reached, the tension motor  58  is de-energized. 
       FIGS. 8-12  illustrate the electric tension control system  100  of the present invention.  FIG. 8  illustrates a side view of the tool with the load cell cover  104  (see  FIG. 2 ) removed. The tension control system  100  includes a donut load cell  110 , a load cell plate  112 , a worm cushion  114  and a tension motor union  118 . The donut load cell  110  measures the tension applied to the tie tail  202 . The tension control system  100  also includes a gear train  76  that distributes the force from the tie tail  202  to the load cell  110 . As the meshed gripper gears pull on the tie tail  202 , the force on each gear tooth is translated to the intermediate gears  78  and the shaft the gears rotate about. The force reaches the gear box  102  and the worm gear  130  and worm  132  contained inside (see  FIG. 9 ). The load cell  110  maintains the position of the worm  132  and the worm shaft  134 . 
     As illustrated in  FIGS. 10-12  the fixed tension motor  58  drives the worm shaft  134  by the tension motor union  118 . The worm shaft  134  is free to move normal to its axis as the tension motor union  118  acts like a spline with the output shaft  120  of the tension motor  58 . The output shaft  120  slides axially with respect to the tension motor  58 . The load cell  110  restrains the normal movement of the worm shaft  134 . As a result, the force applied on the worm shaft  134  from the worm  132  and the worm gear  130  is directed to the load cell  110 . 
     As the load on the worm  132  and worm gear  130  increases, the resultant force is distributed through a worm cushion  114  to a load cell plate  112  into the load cell  110 . The worm cushion  114  is formed from a compliant member, such as urethane, or any material with rubber characteristics. As the worm shaft  134  turns, the resultant force at the worm  132  and worm gear  130  creates a downward force on the worm shaft  134 . Since the tension motor union  118  is fixed to the worm shaft  134 , as the worm shaft  134  moves downward so does the tension motor union  118 . As the tension motor union  118  moves downward, the force compresses the worm cushion  114 , which translates the force to the load cell plate  112  and then into the load cell  110 . 
     The worm cushion  114  decreases the halt rate of the gear train  76  to reduce gear shock. The worm cushion  114  dampens the tension as the tension motor  58  is de-energized thereby reducing the stress or impact on the tool. The worm cushion  114  also acts as a spring by returning the worm  132  to its home position after the desired tension has been reached. 
     An electric controller monitors the output of the load cell  110 . Once the desired tie tension has been achieved, the tension motor  58  is de-energized. The worm cushion  114  of the present invention enables the tension control system  100  to measure an accurate applied tie tension thereby preventing the tool from over tensioning the tie. 
     The electric tension control system  100  also enables force on the tie tail to be output to a recording device, i.e. a computer, for data collection. The electrical tension control system  100  is an improvement over prior mechanical detent systems because typical mechanical detent systems have a tendency to wear over time and change the calibration of the tool. 
     After the desired tension has been reached and the tension motor  58  is de-energized, the controller energizes the set/shear motor  152 . The meshed gears  90 ,  92  maintain the tie tail  202  in place while the ball set and shear mechanism  150  is activated.  FIGS. 3 ,  4  and  13 - 16  illustrate the ball set and shear mechanism  150  of the present invention. 
     As shown in  FIG. 3 , the motor  152  for the ball set and shear mechanism  150  has a threaded rod  154  attached to the output shaft  153  (see  FIG. 3 ) of the set/shear motor  152 . A mating nut  156  runs up and down the threaded rod  154  based on the direction of the rotation of the output shaft  153  (see  FIG. 3 ). The nut  156  is attached to a cutoff ram  158 . The cutoff rain  158  moves toward the anvil  182  as a result of the rotation of the threaded rod  154 . As illustrated in  FIGS. 13 and 14 , the cutoff ram  158  is keyed to the side plates  160  and is connected to the ball set block  170  by a toggle linkage  162 . The toggle linkage  162  forces the ball set block  170  toward the tie head  204 . As illustrated in  FIG. 15 , when the toggle linkage  162  passes over center, the ball set block  170  has traveled the appropriate distance into the tic head for the set block finger  172  to set the ball the desired depth. As the cutoff ram  158  continues toward the anvil  182 , the toggle linkage  162  forces the ball set block  170  away from the tie head  204 . 
     The cutoff ram  158  then contacts the shear block  180  and pushes the shear block  180  toward the anvil  182 . As illustrated in  FIG. 16 , the shear block  180  contacts the tie head  204  and pushes the tie head  204  down past the anvil  182 . Since the tie tail  202  is held above the anvil  182 , the force of the tie head  204  being pushed past the anvil  182  shears the tie tail  202  from the bundle  210  creating a flush cutoff at the tie head  204 . The remaining portion of the tie tail  202  is ejected from the tool by the gripper gears  90 ,  92 . 
     Two electric optical sensors  190 ,  192  monitor the movement of the cutoff rain  158 . Once the cutoff ram  158  moves from the home optical sensor  190 , the electric controller begins to monitor the sensors  190 ,  192 . When the away optical sensor  192  detects the cutoff ram  158 , the controller reverses the set/shear motor  152  and returns the cutoff ram  158  to the home sensor location. The spring loaded shear block  180  travels upwards in the tool with the cutoff ram  158  and the toggle linkage  162  reverses the ball set block  170  returning it to the starting position. Once the home optical sensor  190  detects the returned cutoff ram  158 , the set/shear motor  152  is de-energized and the tension motor  58  is energized preparing the tool to tension another metal tie. 
     Furthermore, while the particular preferred embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the teaching of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.