A STUDY OF THE FACTORS CONTROLLING THE TUBE-SINKING PROCESS FOR POLYMER MATERIALS

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 manufactu red from polymeric materials. The results of a Finite Element study (u sing the ABAQUS Finite Element programme) of the factors influencing t he drawing loads in the tube-sinking process of polymer tubes are pres ented and discussed. The loads at the leading end of the tube, drawn t hrough a die under different conditions of drawing speed, tube wall th ickness, die/tube friction, die reduction and die semi-cone angle, are predicted. These loads define the design of the process parameters an d equipment under the various conditions found in actual operation. Th e 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 dif ferent polymer materials in the process has been predicted. Excellent agreement between the predicted results and experimental data from tri al dies is achieved, which demonstrates that drawing loads, stresses a nd strains can be predicted more accurately using this FE approach tha n previously was possible with classical theoretical analyses of tube sinking. (C) 1997 Elsevier Science S.A.