web position

What are Pneumo-Hydraulic Web Guides?

Many displacement guides, steering guides, unwind / rewind guides manufactured in the 1960’s, 1970's, 1980’s and 1990's were controlled using both pneumatic and hydraulic control systems which are often referred to as pneumo-hydraulic web guides. These web guide were really common before the mass adoption of the electronic (analog and digital) controllers and electric actuators. A lot of these units were predominant in blown film lines, extrusion lines, flexographic printing presses and even in paper converting machines. 

A method of adaptive guiding of a web on a roller is disclosed. The method includes computing an output of a reference model, reading an output of a sensor that indicates a web position, determining a difference between the output of the reference model and the output of the sensor, and updating a set off controller parameters for the roller based on the difference.

Existing edge sensors use the concept of blocking/unblocking to determine web lateral position. The most commonly used sensors employ either ultrasonic or optical signals to detect the web edge position by measuring the amount of signal attenuation due to blocking/unblocking of the signal. The main drawback of this sensing method is nonuniform signal attenuation for web material variations and opacity. The research in this paper develops a new sensor which utilizes the phenomena of light scattering from the web edge and the directional sensitivity of optical fibers to determine the web lateral position.

An introduction to the revolutionary web edge sensor technology is outlined in this article. The sensor technology is based on light scattering and spatial filtering properties of optical fibers.