Most people that are tasked with the tuning of controllers are familiar with three terms; Proportional Gain, Integral Gain, and Derivative Gain, better known as PID. These adjustments are often referred to as “Controller Gain” as they determine the controller’s responsiveness to disturbances. However, in many cases, the dynamic behavior of the actual process may require further action. This would be to prevent the controller from becoming unstable at certain points in the process. This is commonly known as “process gain or progressive gain”.
In unwinding applications, where there are large build-downs, as roll diameter decreases, the system gain must decrease proportionally to ensure a smooth, consistent, quality process. Progressive gain must be implemented. Without this proportional decrease you run the risk of either lack of response at large diameters and/or instability at the core. Depending on the advancements and capabilities of your controller, traditionally, in order to proportionally decrease the gain, your tension controller will need to know what the diameter of the roll is, typically through the use of an ultrasonic sensor, laser sensor, or proximity sensors. If utilizing a PLC for control it can be very time consuming to create the gain calculation, and can mean additional I/O modules.
However, Montalvo tension controllers already include the Progressive Gain software, and I/O’s for any of the diameter sensing options to deliver the precise adjustments you require right out of the box. Taking this one step further, our latest controller technology has allowed us to utilize progressive gain without a diameter measurement. Simply utilizing tension and output can be precise enough for progressive gain.
Progressive Gain is a critical feature in maximizing your productivity and end product quality when dealing with large build-downs, and is just one of the many standard features we have incorporated into our tension controllers.