Pipe extrusion variable-wall die and replacement and installation method

The invention discloses a pipe extrusion wall-changing die which comprises a core rod and a mouth die, a forming cavity is formed between the core rod and the mouth die, the mouth die comprises a mouth die base and a mouth die wall-changing piece, the core rod comprises a core rod base and a core rod wall-changing piece, during installation, the outer surface of the core rod is sleeved with the mouth die base in a penetrating mode, and the mouth die base is sleeved with the mouth die wall-changing piece in a penetrating mode. The die holder is not in contact with the core rod; and the mouth mold wall changing piece is mounted on the right side of the mouth mold base. According to the method disclosed by the invention, the shutdown mold changing and startup time is about 0.5-1h, and the startup time is shortened by 3-11h, so that the mold changing rate is greatly improved, and the mold changing difficulty is reduced; therefore, the die change waste rate is also reduced from 0.6 to 0.8 percent to 0.1 to 0.2 per