Soft Gearing For a Better Wind-up

“Two things repeat themselves in the specification stage of new projects,” Robert C. Baugher, president, says. “Everyone wants more throughput and they want the smallest possible footprint.”Space and throughput demands are especially heavy at the beginning and the end of plastics and rubber continuous production lines, where unwinders or extruders feed the line, and winders spool the product for take-off. The conventional solution, turret winders, has come under scrutiny because increasing their throughput adds complexity and cost. Further, turret winders take significantly more space as additional units are separately. “But non-turret winders pose a problem when they have no automated transfer/cut,” Baugher says. “We didn’t want to add manual operations. And, you can’t automate by adding conventional servo drives and controllers because of cost.”Exploiting ControlRK Design Technologies looked into the ever-broadening range of available servos, amplifiers and controllers, finally opting for PositionServo 940 servo drives from Lenze-AC Tech (Uxbridge, Mass.). “We exploited control with these drives during transfer/cut by setting up dual master, single slave configurations using software electronic gearing,” Baugher explains. “With this, we can change status—if spindle A is master to the traverse guide pre-transfer/cut, then spindle B can become master to the traverse guide after transfer/cut, giving us tremendous flexibility.”The resultant modular, patent-pending, fully automatic transfer/cut non-turret winders position two times the number of winding spindles in a given floor space, compared to turret types. “Our non-turret winder can locate reels on top of each other,” Baugher says, “and high-throughput, space-constrained sites can easily mirror spindles on the back of the same frame. That is important in multiple lines as it allows us to position a dense set of winding spindles on one frame between two lines, and they can have totally independent settings.”The PositionServo drives allow RK Design multiple options for control with configuration. “We use Ethernet within the winder, but the drives can connect directly with DeviceNet, CANopen, PROFIBUS and RS-485 Modbus links,” Baugher says. “Plus, we can monitor and control any 940 drive servo position and speed from any device, from a PLC, an HMI device, or any other 940.”The PositionServo 940 enables a range of spindle positioning choices as well as a range of cut actions. RK Design also cites the drive=s small footprint and adaptability to any AC motor with an encoder. “Most importantly, we can address all parameters across any 940 drive, whether digital, analog or position,” Baugher says.Baugher emphasizes that his company focuses on manufacturing improvement for its customers. Conservatively, its customers routinely realize 30 to 50 percent throughput increases. “But we often do better. Where typical production might be 60 or 70 feet per minute, our multi-spindle, automatic non-turret winders can get 120 to 150 FPM, with 300 FPM on the horizon,” Baugher says. “Software control opens up possibilities, rather than imposing constraints. What used to take new wiring and additional hardware now requires a quick change in the program.”Dave Gehman is an Automation World Contributing Editor.