This stainless steel tray is being ejected from a hydraulic press by a pneumatic cylinder using a closed-loop light sensor to control stroke.
Vollrath formerly had to set the depth of the lower die using shims and spacers. The time for setup ate into production time, so Werner Kraenzler, manufacturing engineer at Vollrath, looked for a way to automate positioning of the bottom of the die. Integrating a control with the eject cylinder would offer a simple and compact solution, but conventional methods posed serious limitations.
Kraenzler wanted a position sensor that could be adjusted remotely. Reed and proximity switches could not easily be repositioned, and linear pots would not stand up to the repeated shock of the hydraulic press. Plus, stray EMI and RFI noise could interfere with many other types of sensors.
Arriving at a solution
Kraenzler found a solution with the iNSiGHT air cylinder from Motion Controls LLC, Hartford, Wis. Brad Engstrad, president of Motion Controls explained that iNSiGHT is a pneumatic cylinder of standard dimensions incorporating QVLA technology for internally sensing position of the cylinder’s piston. The patented QVLA technique uses light from an LED to illuminate the volume inside the cap end of the cylinder. As the piston moves closer to or away from the cap end, the intensity of the reflected light changes accordingly. A light-detecting diode senses the change in reflected light, which correlates to the piston position. Circuitry within the QVLA generates an electrical signal representative of piston position, and without having to use magnets or gun-drilled piston rods.
Kraenzler says that instead of having to set the depth of the die manually, operators can now extend or retract the cylinder’s piston rod until a digital readout shows the target position. After the position is locked in, the operator can resume production of trays with the press set to the new depth. The quick-change act not only increases productivity, but also makes the press more versatile by allowing a variety of sizes to be run on a single machine.
For more information on iNSiGHT cylinders and QVLA technology, call Motion Controls LLC at (262) 673-9255, or visit motioncontrolsllc.com.