The case for regenerative AC drive motors
During the operation of any converting machine, whether for film, foil, wire, paper or board, plus most large printing presses, rolls of materials are handled by unwinds, often still driven by pneumatically operated braking systems. The traditional tension control system for an unwind stand is a simple mechanical brake. In principal, the unwind brake mechanically operates much like the braking system on your car, with a disk, caliper and pads, but is controlled by a tension sensor linked to a set point controller. As the roll unwinds, the tension is maintained by the brake for smooth passage of the material through the dies or rollers, resulting in better package alignment, less wrinkling, better print registration, even more consistent wire dimensioning and other production positives. These mechanical brake unwinds are effective in controlling the tension, but have inherent problems of heat and power loss, plus mechanical wear and constant maintenance needs, substantially impacting machine uptime.
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