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Question: I have an older style roll stand behind my sheeter with a spring-loaded handle to control the friction on the brake drum. What can be done to upgrade this to a better system and possibly introduce automatic tension control?

Answer: There are a couple of ways to improve your brake and tension system. First, replace the mechanical brake drum arrangement with a pneumatic type brake disc. This will provide the Operator with the ability to adjust the brake pressure more accurately. Next, consider the tension control system itself. There are many types of automatic tension control systems. Three of the most popular designs that are used are the ultrasonic, proportional and load cell.

The ultrasonic type uses a sensor to measure the reducing diameter of the roll and through an electro-pneumatic converter converts the electrical signal to a pneumatic output, decreasing the brake pressure, as the roll gets smaller.

The proportional style uses two signals, one a series of pulses from the sheeter’s encoder associated with the length that is being drawn in to the cutter and the second from the roll stand after each complete rotation. The two inputs calculate the roll diameter and then send a signal to the converter governing the brake pressure.

The load cell mode of tension control monitors the pressure exerted by the web on an idler roll. This electrical signal is sent to the converter, reducing the brake if the pressure is to great and increasing brake if the pressure is less than the preset limit.