IMC has developed a new calendering system with inline pre-meter 2-Roll calender and computerized 2-Roll calender with closed loop gap control for a PTFE extrusion process to ensure both thickness and density control.
The dual station Calendering system is used inline with a PTFE extrusion process to 10” wide to ensure both thickness and density. The Pre-Meter calender has 12" diameter x 14" face chrome plated steel rolls finished to 1 RMS. Each roll has an internal fluid path for oil heating to 250° F. The fluid path is engineered to provide the most efficient heat distribution. Actual fluid temperature is fed back to the system controller with digital readout. A wedge block assembly provides gap control to .200” in .001” increments and is hydraulically loaded to 2500 PLI applied from the bottom by hydraulic cylinders at each journal displayed by a pressure gauge.
As the pre metered material is fed to the Computerized Metering Calender it passes through a pneumatic loaded dancer with position sensor to monitor tension and provide a tension signal to maintain the programmed tension/speed between the units.
The 2-Roll Computerized Metering Calender has two (2) 16" diameter by 14" face heated rolls to 250°F with internal fluid path and provides automatic final product metering to +/-.0001” thickness accuracy. Roll gap is controlled automatically by servo driven differential screws positioned at each journal. Gap parallelism is maintained by a mechanical phase adjustment assembly between the differential screws. A thickness gauge located at the exit side of the computerized calender measures web thickness and produces an output signal for the gap controller where it is compared to the programmed gap setting. An error signal is generated and sent to the servo motor controller which continuously adjusts the gap setting to maintain pre-selected web thickness providing closed-loop control. A program algorithm limits the actual gap adjustment to avoid constant “hunting” caused by continuous thickness readout variation from the gauge. The selected gap is set at the operator touch screen and has digital readout with 0.0001” resolution. Gap controls also include “Open” “Close” push buttons. The computerized gap system will provide calendering pressure to 3125 PLI (25,000 lbs. separating force on a 8" wide web). Calendering pressure at each journal is monitored by load cells and displayed by digital readouts.
Independent Machine Company custom designs and manufactures a complete line of web processing machinery for a broad range of industries for production and development applications