Liquid-filling pressing forming die for large-medium automotive axle case pipe fitting

The invention discloses a liquid-filling pressing forming die for a large-medium automotive axle case pipe fitting. An upper die (10) and a lower die (17) of the die are respectively fixed on a U-shaped upper die seat (12) and a U-shaped lower die seat (18); front and rear side vertical arms (H, H') of the lower die seat (18) move on the inner side surfaces of front and rear side vertical arms (G, G') of the upper die seat (12); a front die (25) and a rear die (26) are driven by short-stroke hydraulic cylinders I and II (24, 24') fixed on the lower die seat (18) to carry out opposite synchronous pressing on a preformed pipe billet, and in the die closing process, cavities inside the front die (25) and the rear die (26) are totally in contact with the front and rear side surfaces of the upper die (10) and the lower die (17); a left pressure head (6) and a right pressure head (14) are driven by left and right sliding blocks of a hydraulic press to carry out left and right synchronous sealing on the end parts of the preformed pipe billet. The liquid-filling pressing forming die for the large-medium automotive axle case pipe fitting is used on the four-way hydraulic press, has independent actions in six directions, and is high in control accuracy, high in forming quality of the pipe fitting, reliable in die structure and convenient to blow down and pick up.