According to the structure characteristics of four-way pipe plastic parts, a mould with side and flexible core-pulling was designed. Hydraulic mechanism was adopted in the side core-pulling, which to accomplish linear core-pulling motions, and the flexible core-pulling accomplished arc core-pulling motions. The sequence of opening and closing action of cylinder was controlled by hydraulic pressure core-pulling mechanism, which avoided the problem of dynamic interference between cores when demoulding. The co...