Plastic shower pipe negative pressure forming means

Provided is a negative pressure forming device for plastic shower pipe. According to the invention, an inner mouth die has a short column at the front, a bearing disc at the back and a taper inner bore; a mandrel is sleeved on the short column of the inner mouth die; an electric heater is arranged at the exterior side of the mandrel; an outer mouth die is arranged to block the front of the inner mouth die; a runner gap is formed between the taper inner bore of the outer mouth die and a taper outer periphery at the front of the short column of the inner mouth die; the mandrel is provided with a feed inlet communicating with the runner gap; the back of the inner mouth die is butted with a vacuum chamber sleeve which is provided with bores for insertion of inner pipes; a vacuum chamber back cover is arranged at the back of the vacuum chamber sleeve; the bores in the vacuum chamber sleeve are connected with a vacuum pump. The forming device provided in the invention can be used for formation of accidented grooves of outer walls of plastic shower pipes and continuous production of plastic shower pipes with jacketed walls or external walls which have accidented grooves and resistance todead fold; on-line forming is realized, thereby avoiding reheaing, saving energy and reducing consumption; atmosphere is used as the medium for formation in the invention, thereby realizing environmental protection.