Large-diameter-thickness-ratio multi-way pipe liquid filling convex hole forming method

The invention discloses a method for forming a liquid filling convex hole of a multi-way pipe with a large diameter-thickness ratio. The method comprises the following steps of A, pre-bulging, B, opening a prefabricated hole, C, mounting a convex hole mold, D, sealing and E, forming the liquid filling convex hole. According to the method, convex hole forming of liquid filling of the multi-way pipe with the large diameter-thickness ratio is achieved, high-pressure liquid is filled into a workpiece, and the convex hole die is pushed through liquid pressure to achieve branch pipe forming. Production of complex pipe fittings such as variable cross-section pipe fittings and axis bending pipe fittings can be achieved, the forming quality of the multi-way pipe with the large diameter-thickness ratio is effectively improved, and due to the fact that high-pressure liquid supporting exists in a pipe blank in the hole protruding process, the quality defects such as hole periphery distortion, wrinkling, poor die attachin