Isolated torsional-transfer combined tong apparatus

Abstract

An apparatus for making up and breaking out of pipe, bolts or other threaded members, and for measuring the amount of torque being applied to the threaded connection, without causing the application of undesirable transverse forces during the tightening or loosening process. The apparatus includes a conventional power-driven lead tong, a back-up tong with a pivotal mounted inner frame which cooperates with a load cell, and an isolated torsional transfer structure which interconnects the lead tong and back-up tong through pairs of three mutually peripendicular linear slides. The load cell, pivotally mounted inner frame and external housing of the back-up tong cooperate to produce a torque measurement without creating any unpaired linear forces against the connection being made. The three mutually perpendicular slides of the interconnecting frame allow for the transferal of torque between the lead tong and back-up tong, so that their relative tendencies to rotate about the work piece in opposite direction is resisted, but the slides eliminate any net linear forces between tongs. By eliminating all unpaired linear forces arising out of the torque measuring process, and by eliminating all unpaired linear forces arising out of each tong resisting the other tong's tendency to rotate, threaded connections are tightened and loosened by pure torque alone, with no transverse or bending forces applied to the connection.