A study of the factors controlling the tube-sinking process for polymer materials

Abstract

The tube sinking process for reducing the diameter of a pipe or a tube by drawing through a conical die has been studied for tubes manufactured from polymeric materials. The results of a Finite Element study (using the ABAQUS Finite Element programme) of the factors influencing the drawing loads in the tube-sinking process of polymer tubes are presented and discussed. The loads at the leading end of the tube, drawn through a die under different conditions of drawing speed, tube wall thickness, die/tube friction, die reduction and die semi-cone angle, are predicted. These loads define the design of the process parameters and equipment under the various conditions found in actual operation. The characteristic mechanical behaviour of the polymer materials studied is efficiently represented from the results of uniaxial testing by a piecewise linear elastic/plastic material model, and the effect of different polymer materials in the process has been predicted. Excellent agreement between the predicted results and experimental data from trial dies is achieved, which demonstrates that drawing loads, stresses and strains can be predicted more accurately using this FE approach than previously was possible with classical theoretical analyses of tube sinking.