Molded Insulating Hinge for Bipolar Instruments

Abstract

An electrosurgical instrument includes a pair of first and second elongated shafts each having an end effector attached to a distal end thereof and a handle. The handle is movable from a first position wherein the end effectors are disposed in spaced relation relative to one another to a second position wherein the end effectors are closer relative to one another. Each of the elongated shafts includes a hinge plate which mounts atop a pivot assembly for effecting movement of the end effectors relative to one another. The instrument also includes a hinge assembly made from an overmold composition which encapsulates and secures the hinge plates and the pivot assembly. The overmold composition is made from an electrically insulating material which insulates the end effectors from one another.

1 . A method of forming a hinge assembly comprising the steps of:
 providing a pair of first and second elongated shafts each having an end effector attached to a distal end thereof, a handle and a hinge plate, the handle for effecting movement of the end effectors relative to one another,   the hinge plate of the first elongated shaft and the hinge plate of the second elongated shaft mountable about a pivot pin having a reinforcing portion;   mounting the elongated shafts to a die block;   introducing an overmold composition into the die block to encapsulate at least a portion of the hinge plates;   extruding an amount of the overmold composition through the pivot pin to a side of the hinge plate of the second elongated shaft opposite the hinge plate of the first elongated shaft around the reinforcing portion of the pivot pin to form a retention tab; and   curing the overmold composition to form a hinge assembly.   
     
     
         2 . A method according to  claim 1 , wherein after a portion of the overmold composition is extruded around the reinforcing portion of the pivot pin, the method further comprises stamping the retention tab against a side of the hinge plate of the second elongated shaft. 
     
     
         3 . A method according to  claim 2 , wherein the step of stamping secures the hinge plates in close abutment relative to one another about the pivot pin. 
     
     
         4 . A method according to  claim 2 , wherein the step of stamping secures the hinge assembly by mechanically engaging a portion thereof to one of the hinge plates. 
     
     
         5 . A method according to  claim 1 , wherein each of the hinge plates mounts atop the pivot pin for effecting movement of the end effectors relative to one another and wherein the step of securing the hinge assembly between the hinge plates and mechanically engaging a portion of the hinge plate includes biasing the end effectors in a predetermined open, closed or intermediary position. 
     
     
         6 . A method according to  claim 1 , wherein an outer surface of the hinge plate of the second elongated shaft includes at least two interfaces that mechanically engage the retention tab. 
     
     
         7 . A method according to  claim 1 , wherein the pivot includes a series of undulations about an outer periphery thereof configured to strengthen mechanical interfacing of the overmold composition to the pivot pin.