Mechanism Design Of Iron Roughneck Torque Wrench And Mechanical Analysis Of Pipe String Holder

The make-up and break-out operations on the pipe string are the key link in drilling operation.Iron roughneck is the most automated equipment in pipe string up-shackle operation.As a part of the whole iron roughneck mechanism,the torque wrench has the function of completing the action of fastening and shackling,carrying the maximum load and requiring frequent reciprocating operation.The performance of clamp teeth directly affects the working efficiency of iron roughneck.In this paper,a new non-bite-claw clamp tooth is designed to replace the straight clamp tooth with the purpose of less than 1mm of tubular bite and longer tooth life.The main working part is cylindrical clamping body,which is made of 20 CrMnTi alloy steel.The clamping body is fixed on the base of the clamp tooth by spring.The bottom of the base has a wedge angle.When the torque wrench is shackled,it can form a self-locking to prevent slipping.The non-bite cylindrical clamp is in contact with the external wall of the pipe string in the shackle operation of the punching pliers in the form of line contact of two parallel shaft cylinders.In view of this,the nonlinear contact stress between the clamping body and the pipe string is considered,and based on the elastic mechanics theory and the plastic yield criterion.The contact stress and plastic deformation conditions of straight teeth and cylindrical clamps and the outer wall of pipe string in the process of lifting and unlocking were compared and analyzed,and the relations between the factors and deformation and stress were established when the teeth were in contact with the pipe string.Using finite element simulation to analyze the influence of different materials of different sizes on the deformation and stress of the clamped pipe string,it is determined that the stress value generated by the clamp body on the external wall of the pipe string is lower than the allowable stress,which proves this design is reasonable.This non-bite cylindrical clamps are designed to reduce damage to the string and increase the service life of the clamps.