The collapsible core pulling system consists of core and cavity, which are the main part in the mould structure, which is characterized by the following : the fixed bar is in the main core, outside which is the sliding rail.
In the sliding cavity there is the active cavity and in the active cavity the stiffening rib is installed next to the fixed bar. In the middle of the stiffening rib there is the locating slot, and outside is the belling core. The belling core is consisted of the large sliding block and the small one, which work with clamping plate. Between the large and small sliding block, there are two active slots. One is connected with the lower surface of the locating slot ,in the middle of which a pad is installed, and a baffle plate is located. A support plate of small sliding block is installed between active slot and the slot of stiffening rib, above which is the support plate of the large sliding block. The large one has the other baffle plate, and they are connected with each other, the top of the baffle plate is connected with draw bar, and the draw bar is driven by the hydro-cylinder.