Forming method for hollow pipe body

Abstract

The invention relates to a forming method for a hollow pipe body. Before die closure, an upper core-pulling slide block in an upper cavity is located at a moving-backwards dead-point position, and a lower core-pulling slide block in a lower cavity is also located at the rear dead-point position; after the die closure, the upper core-pulling slide block and the lower core-pulling slide block move forwards to a front dead-point position simultaneously according to a set time; internal high-pressure air blowing is carried out from the lower part of a pre-blowing blank; the upper core-pulling slide block and the lower core-pulling slide block move backwards to the rear dead-point position simultaneously; and an upper die moves upwards and then a product is taken out. According to the technicalscheme, the original integrated cavity is split into the cavities with the core-pulling slide blocks and capable of partially moving forwards and backwards independently, then the moving-forwards time of the core-pulling slide blocks is delayed, the contact time of the blank capable of making contact with the cavities at first at the position, and the cavities, is delayed, so that the blank at the position is stretched well, and then the previous phenomenon of excessive stretching of an area with an insufficient wall thickness is alleviated.

Description

technical field [0001] The invention belongs to the technical field of blow molding preparation of hollow pipe bodies, in particular to a method for forming hollow pipe bodies. Background technique [0002] At present, the molding methods of plastic hollow tubes are mainly extrusion molding and blow molding. Extrusion molding has great advantages in forming linear hollow tubes. The wall thickness of the tubes is uniform and the length is not limited. The cross-section of the pipe is unique during the molding process, and it is impossible to achieve alternate changes in thick and thin cross-sections on a pipe, and it is also impossible to produce curved hollow pipes, and the design freedom of hollow pipes is low; while blowing In addition to forming curved hollow tubes, plastic molding can also achieve alternate changes in thick and thin cross-sections on the same tube, so it is widely used. [0003] However, in recent years, with the continuous promotion of its application ...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a hollow tube forming method to solve the problem in the prior art that when the hollow tube is partially or entirely flat, the wall thickness near this area is too thin and does not meet the requirements

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