Patent Publication Number: US-7587918-B2

Title: Crimping device

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a crimping device and a method of fastening a crimp contact to a wire, the wire conductor and wire insulation being fastenable to the crimp contact by means of a crimper and anvil, and the crimping force that thereby arises on the anvil being measurable by means of a force sensor. 
   U.S. Pat. No. 5,937,505 shows a crimping press by which an electrical contact can be fastened onto the end of a wire. A crimping punch and a crimping anvil together fasten the crimp contact to the wire end, the force arising in the crimping anvil being measurable by means of a force sensor. 
   A disadvantage of such devices is that the entire crimping force (conductor crimping force and insulation crimping force) is measured. It also is disadvantageous that the sensor is built into a wear part. 
   SUMMARY OF THE INVENTION 
   It is here that the present invention sets out to provide a remedy. The invention provides a solution for avoiding the disadvantages of the known device, and creating a device and a method that enable precise measurement of the crimping force. 
   The advantages achieved by means of the invention include that the force required to produce the conductor crimp is measurable. The force in the conductor anvil is transmitted to only one sensor. The pattern of the force during the crimping operation is measured and analyzed, the quality of the crimped connection being assessed by reference to the force curve. The force measurement according to the present invention meets the high requirements for quality assurance. 
   In the device according to the present invention, provided on each crimper is an anvil, the crimping force arising on a conductor anvil being measurable by means of a force sensor. 

   
     DESCRIPTION OF THE DRAWINGS 
     The above, as well as other, advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment when considered in the light of the accompanying drawings in which: 
       FIG. 1  a perspective view of a crimping press according to the present invention; 
       FIG. 2  is an enlarged, exploded perspective view of a lower tool of the crimping press show in  FIG. 1 ; 
       FIG. 3  is enlarged, exploded perspective view of a crimper, an anvil, and a crimp contact before crimping; 
       FIG. 4  is enlarged, exploded perspective view of the crimper, the anvil, and the crimp contact during crimping; 
       FIG. 5  is enlarged, exploded perspective view of the crimp contact after crimping; 
       FIG. 6  is enlarged, exploded perspective view of the conductor anvil with a force sensor; and 
       FIG. 7  is enlarged, exploded perspective view of the force sensor of  FIG. 6  in partial cross section. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a crimping press  1  according to the present invention comprising a first housing  2  on which a press motor  3  that drives a gear  4  is arranged. Provided on the output side of the gear is an eccentric device that converts the rotational motion of the motor  3  and gear  4  into a linear up-and-down motion that can be transferred to a press carriage  5 , the press carriage  5  being guided by means of guides  6 . Provided for the production of a crimped fastening between a crimp contact  22  ( FIG. 2 ) and wire  18 , and arranged on the press carriage  5 , is an upper tool  7  with conductor crimper  8 , an insulation crimper  9 , and a cutter plunger  10 , the upper tool  7  working in conjunction with a lower tool  11 . The lower tool  11  comprises an anvil part  15 , a sensor part  16 , and a first supporting part  17 . The crimp contacts  22  to be processed are parts of a contact belt  12  that is advanced by a contact advancer  13 . An advancing motor  14  drives the contact advancer  13 . 
     FIG. 2  shows the lower tool  11  with the anvil part  15 , the sensor part  16 , and the first supporting part  17 . Arranged on the anvil part  15  is a conductor anvil  19  and an insulation anvil  21  ( FIG. 3 ). Arranged on the sensor part  16  is a force sensor  20  on which the force that arises in the conductor anvil  19  acts, the force sensor  20  in turn being supported on the first supporting part  17 . The first supporting part  17  itself is supported on the first housing  2 . 
     FIG. 3  shows the crimper  8 ,  9 , the conductor anvil  19 , the insulation anvil  21 , and a one of the crimp contacts  22  of the contact belt  12  before the crimping operation. The belted crimp contact  22  rests with its conductor crimp  23  on the conductor anvil  19  and with its insulation crimp  24  on the insulation anvil  21 . The wire  18  whose end is stripped of insulation is positioned above the crimp contact  22 , a free wire conductor  25  lying above the conductor crimp  23 , and a wire insulation  26  lying above the insulation crimp  24 . The conductor crimp  23  and insulation crimp  24  respectively are essentially V-shaped and open toward the top. The wire end is positioned in the conductor crimp  23  or insulation crimp  24  respectively by means of the lowering movement of the crimper  8 ,  9 . 
     FIG. 4  shows the crimper  8 ,  9 , the conductor anvil  19 , and the insulation anvil  21  during crimping of the crimp contact  22  of the contact belt  12 , the conductor crimp  23 , and the insulation crimp  24  being thereby plastically deformed as shown in  FIG. 5 . The conductor crimp  23  embraces the strands of the wire conductor  25 , and the insulation crimp  24  embraces the wire insulation  26 . During the crimping operation, the crimp contact  22  is separated from the contact belt  12 . 
     FIG. 6  shows the conductor anvil  19  with the force sensor  20 , on which the force that arises in the conductor anvil  19  during the crimping operation acts. The conductor anvil  19  rests on a sensor body  27  which in turn rests on the first supporting part  17 . Instead of the one force sensor  20 , several force sensors can be provided that measure the force that arises in the conductor anvil  19 . For example, wire strain gauges arranged on the conductor anvil  19  can measure the crimping force. 
     FIG. 7  shows details of the force sensor  20  with the sensor body  27 . A disk-shaped piezoelectric element  28  that responds to the force of the conductor anvil  19  is arranged between a first disk  29  and a second disk  30  and electrically insulated from the sensor body  27  by means of a plastic ring  31 . The sensor body  27  and the first disk  29  are made of one piece, the second disk  30  being threaded onto the sensor body  27 . Conducting pathways integrated in a foil  32  conduct the signal of the piezoelectric element  28  to a plug connector  33 . 
   In a further exemplary embodiment, the sensor body  27  is executed as a threaded screw with screw head, and the first disk  29  is executed as a loose disk with drilled hole. The threaded screw penetrates the drilled hole and the piezoelectric element  28 . The second disk  30  is screwed onto the end of the threaded screw with its internal thread and then the two disks  29 ,  30  are screwed by means of the screw head until the required pretension of the piezoelectric element  28  is attained. 
   In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.