Abstract:

A type of rotary bi-color hot runner mould was designed for production of the bi-color plastic parts of knob cover. In this mould, a four-plate with 3-time opening bi-color moldbase was adopted. The bi-color mould was composed of two sub-moulds, in which the first one was the injection sub-mould for the plastic lining matrix, the second one was the injection sub-mould for the plastic over layer, and the cavity layout of the two sub-molds was based on the one mold with two cavities. In the two sub-moulds, the combination of hot runner and cold runner was used for gating. In the first sub-mould, the three inner wall hidden gates were used for gating in the single cavity, and the three inner wall hidden gates were adopted for gating as well in the second sub-mould. The difficulty in filling the cylindrical wall mold cavity was overcome through this design scheme, and the automatic removal of runner waste was guaranteed. In this mould, 36 locking-block T-groove driving slider mechanisms with a similar structure and a small design space were designed to implement side core pulling demolding, which could reduce the overall size of the mould. These 36 mechanisms were driven by 3 times opening of the plates, and a type of inserting bar mechanism was designed to control the sequential opening and closing of the plates. This mechanism is reliable for operation.

Key words: core pulling mechanism, bi-color molding, mold structure, injection, hot runner