Tube-bending plier

Abstract

A tube-bending plier is described having opposing arcuately grooved registering jaws defining a cylindrical engagement segment sized to accept tubing of a particular outside diameter, expanding to oppositely curving arcuately grooved side-jaw mandrel surfaces where, (i) in a first embodiment, the plier handles extending from the plier couple are configured for significantly increasing the distance between the handles for applying torque (τ) relative to a twisting axis aligned in the plane of and extending between the plier handles pivotally closing plier jaws for bending a tube held perpendicularly extending from the plier jaws, and (ii) in a second embodiment, the closed plier jaws and oppositely curving side-jaw mandrel surfaces define a tube bending plane oriented at an acute angle relative to the plane of the pivoting plier handles for applying torque (τ) for bending a tube held within the plier jaws.

1 . In a tube-bending plier having oppositely arcuately grooved registering jaws with oppositely curving, arcuately grooved, side-jaw mandrel bending surfaces sized to accept tubing of a selected outside diameter, an improvement comprising semi-cylindrical engagement segments in the arcuately grooved registering jaws for providing a cylindrical engagement segment for grasping and holding the tube with a length comparable to the selected outside tube diameter, and wherein each curving, arcuately grooved, side-jaw mandrel bending surface sized for the selected tube diameter curves tangentially from an end of each semi-cylindrical engagement segment. 
   
   
       2 . The tube-bending plier of  claim 1  wherein plier handles extending from a pivoting couple of the plier for closing and opening the plier jaws are configured for significantly increasing distance between the handles for applying torque (τ) relative to a twisting axis aligned in a plane defined by, and extending between the pivoting plier handles. 
   
   
       3 . The tube-bending plier of  claim 1  wherein the opposing, arcuately grooved, registering jaws and arcuately grooved side-jaw mandrel surfaces of the plier are oriented for providing a bending plane at an acute angle relative to a plane defined by the pivoting plier handles opening and closing the plier jaws for increasing torque (τ) for bending the tube held within the jaws of the plier. 
   
   
       4 . The tube-bending plier of  claim 1  wherein the curving, arcuately grooved, side-jaw mandrel surfaces sized for the selected tube diameter curve tangentially from each end of each semi-cylindrical engagement segment providing a front-end, upper and lower mandrel bending surfaces and a rear-end upper and lower mandrel bending surfaces. 
   
   
       5 . The tube-bending plier of  claim 3  wherein the curving, arcuately grooved, side-jaw mandrel surfaces sized for the selected tube diameter curve tangentially from each end of each semi-cylindrical engagement segment providing a front-end, upper and lower mandrel bending surfaces and a rear-end upper and lower mandrel bending surfaces.