Axial dual-direction positioning and stretching hollow blow molding method

Abstract

The invention provides an axial dual-direction positioning and stretching hollow blow molding method. Bearing devices for transitorily bearing the bottoms of bottle blanks are arranged in die cavities. A blow-molded container molding method includes the following steps that 1, the bottle blanks are heated to the stretching temperature, and stretching and pre-blow molding are carried out at the same time; 2, when the bottle blanks are stretched to the positions where the bearing devices are located, the bearing devices bear the centers of the bottoms of the bottle blanks which are gradually stretched and expand, the stretching speed is reduced or stretching is suspended at the positions where borne points of the bottoms of the bottle blanks are located, and the peripheries of the borne points are continuously stretched under the effects of air pressure and the inertia of materials; and 3, after cone bases are pre-formed, the bearing devices withdraw or move along with stretching rods, the stretching rods continue to stretch, the air pressure is injected, then cooling is carried out, and blow-molded containers are formed. The materials at the bottoms of the bottle blanks are fully stretched through bearing in the step 2, the materials are more evenly distributed at the bottoms of bottles, and better cooling shaping can be achieved.

Description

technical field [0001] The invention relates to the technical field of blow molding container molding, in particular to a hollow blow molding method for axial and bidirectional orientation stretching. Background technique [0002] At present, in the process of blow molding container molding, especially in the two-step blow molding method of injection stretch blowing, the axial stretching of the preform basically touches the inner bottom of the preform through a stretch rod (round steel rod) Stretch the preform to the bottom of the cavity in one go. During the stretching process of the stretch rod, compressed air is injected at the same time, and the preform is inflated with the help of compressed air to make it cling to the cavity wall of the mold, and the hollow plastic product is obtained after cooling and shaping. When the preform is stretched to contact with the metal at the bottom of the mold cavity, the bottom of the preform cools faster, and it is difficult for the m...

AI Technical Summary

Problems solved by technology

When the preform is stretched to contact with the metal at the bottom of the mold cavity, the bottom of the preform cools faster, and it is difficult for the material to be fully stretched due to the limited stretching space, resulting in material accumulation at the bottom of the container, resulting in waste of material, resulting in stress concentration, making The bottom of the container is easy to crack, especially on large-capacity containers (above 5L)

In addition, when the vertical stretch size of the preform is large, the stretching rod is prone to unstable speed, insufficient rigidity, and eccentricity at the bottom of the preform, resulting in uneven wall thickness of the blown container and affecting the overall strength of the container

Images