Study and Simulation of the effect of Spider Geometry on the Weld Lines in Extruded Plastic Pipe

In this paper, we try to decrease the relaxation time, which inversely correspond to applied shear stress in material logarithmically by changing the geometry of spider. For increase of strength in weld line region, high local shear stresses in associate of tensional stresses and subsequent orientations by present of spider should be decrease. Also, polymer chains should orientate themselves to make a high degree of entanglement and high quality weld line in spider’s line. This can be obtaining by possible reduction of applied stress relaxation time. By using Mold Flow package and making an extrusion process conditions, analyses was done on four arbitrary spider geometries. Analyze of simulation results shows that Superior spider decrease the relaxation time and the effect of weld line on strength parameters and increase the fatigue life of pipe.