Longitudinal stretching line for anti-film transverse shrinkage

Abstract

The invention relates to a vertical stretching production line for preventing the transverse shrinkage of a film. An annular groove is arranged outside each of two effective-length ends of the surface of each of a large cold roller and a small cold roller of a sheet casting machine, two ends of each of preheating rollers, stretching rollers, pressure rollers and fixing rollers of a vertical stretching machine are provided with grooves respectively, the grooves are same to each other, the cross section of each of the grooves is U-shaped, and the inner side of each of the grooves parallels to the outer side, and the inner side and the outer side are vertical to the central line of the respective roller. The inner sides and the outer sides of the grooves at same ends of all the rollers are correspondingly positioned in two planes vertical to the central lines of the rollers respectively. Guiding rollers of the sheet casting machine and guiding rollers of the vertical stretching machine also have same grooves respectively. A plastic melt is extruded between the large cold roller and the small cold roller to form a thick plastic sheet and form a ridge at each of two sides of the upper surface and the lower surface, the ridges are sequentially embedded in the grooves of all the rollers when the thick plastic sheet sequentially goes through all the rollers of the vertical stretching machine, and two lateral inward tensions of the film along the axes of the rollers during balancing the vertical stretching substantially reduce the transverse shrinkage of the film, ensure the uniformity of the film and improve the quality and output of the film.

Description

technical field [0001] The invention relates to a film stretching production machine, in particular to a longitudinal stretching production line for preventing film transverse shrinkage. Background technique [0002] In the existing film longitudinal stretching production line, the plastic melt is extruded through the die of the casting machine, and formed into thick plastic sheets under the action of the large cold roll and the small cold roll, and the plastic thick sheets are pre-processed by the longitudinal stretching machine in turn. The preheating roll in the hot zone, the stretching roll and press roll in the stretching zone, and the setting roll in the setting zone perform longitudinal stretching. During the longitudinal stretching process, due to the inherent characteristics of the plastic material, the transverse direction of the film is subjected to a large inward tension on both sides, and the stretched film produces a large transverse shrinkage along the axial d...

AI Technical Summary

Problems solved by technology

Although this device can prevent the lateral shrinkage of the film during the longitudinal stretching process, its structure is complex and difficult to install, and it is difficult to control the force of the cylinder on the pressure roller during use. If the force is too small, it will not be able to prevent shrinkage. If it is too large, it will hinder the normal rotation of the take-off roller and affect the longitudinal stretching

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