A method for axial and bidirectional orientation stretching hollow blow molding

Abstract

The invention provides a hollow blow molding method for positioning stretching in both axial and bidirectional directions. A supporting device for briefly supporting the bottom of the bottle blank is provided in the mold cavity. The molding of the blow molding container includes the following steps: step 1, heating the bottle blank To the stretching temperature, pre-blowing while stretching; step 2, when stretching to the position of the supporting device, the supporting device supports the center of the bottom of the preform that has been gradually stretched and expanded, and the bottom of the preform is Slow down the stretching speed or suspend stretching at the position of the supporting point, and the periphery of the supported point will continue to stretch under the action of air pressure and the inertia of its own material; step 3, after the cone bottom is formed in advance, the supporting device retracts or follows the stretching The rod moves, the stretch rod continues to stretch and injects air pressure, then cools to form the blown container. Through the support in step 2, the material at the bottom of the preform is fully stretched and distributed more evenly at the bottom of the bottle, which can achieve better cooling and shaping.

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

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