Abstract: According to the structural characteristics of A-pillar guard board of a vehicle， a large injection mold was designed. The problem in the melt filling of large thin-walled plastic parts was solved by using a sequential valve gating hot runner. The bending and fracture of inclined pushrod problems were solved by using a double inclined push rod and guide rod inclined push rod lateral core-pulling mechanism. The mold was contrasted through the combination of diaphragm water wells， inclined water pipes， and straight-through water pipes. Through using such a nearly conformal waterway of temperature control system， the forming cycle was controlled within 30 s， decreasing by about 10 % in comparison to conventional molds. The molded plastic parts obtained a dimensional accuracy of MT3.

Key words: door cladding under A-pillar of vehicle, hot runner with sequential valve gating, large injection mold, double inclined push rod, guide rod for inclined push rod