The problem of uneven thickness of PVC protective film film should be paid attention to

The uneven thickness of the stretched film is mainly caused by two situations:

1. The film itself from the calender is not uniform in thickness, which will eventually cause the thickness of the stretched product to be different;

2. During the stretching process, due to air convection, the transverse temperature of the film is different, resulting in different thickness of the stretched film, and finally resulting in different thicknesses of the finished material roll along the transverse direction. It can be solved by adjusting the four-roll calender. Specifically, the shaft crossing device of the middle roller and the reverse bending device of the lower roller can be adjusted;

In addition, it is necessary to control the material storage between the rolls, so as to avoid the entry of cold material and affect the uniformity of film stretching. The diameter of the front wheel and the upper wheel is not more than 250mm, the upper wheel and the middle wheel are 15~30mm, and the middle wheel and the lower wheel are 10~15mm. In case o, the temperature of each point of the film is different due to the different air convection in the transverse direction, so that the transverse thickness of the stretched film is inconsistent.

According to practical experience, generally both ends of the film tend to become thicker, because the air convection on both sides is faster than the middle, so the temperature on both sides is lower. Therefore, the film can also be used to cover both sides of the widening machine. If the above methods can not solve the problem, you can install a jet pipe to make up for it. It is placed horizontally at a distance of 150mm from the film, and the nozzle is required to be a duckbill type with a micro valve to adjust the exhaust volume, so that the air flow out is softer. Where the film is thin, the exhaust valve can be opened appropriately, and the exhaust valve can be closed in other places.