Method and apparatus for monitoring the thickness of a foamed extrudate

Abstract

An apparatus adapted to be positioned downstream of a foam extrusion die in an environmental control or vacuum chamber for remote monitoring of the thickness and profile of foam boards, planks and like extrudates soon after the extrudate exits the die and takes its final shape, is characterized by opposed, relatively narrow shoes on opposite sides of the extrudate path and respective carriages therefor which together are movable transversely with respect to the extrudate path by respective worms and translating nuts and a common worm drive. One shoe is operative to support the bottom surface of the extrudate in a predetermined position while the other shoe rides on the extrudate and is position monitored by a transducer operative then to provide an output signal representative of the spacing between the shoes, and thus the thickness of the extrudate passing between the shoes, to remote monitoring circuitry located outside of the vacuum chamber. Through operation of the common worm drive, extrudate thickness is measured at points along the width of the extrudate for overall thickness and profile monitoring. Quick and responsive die adjustments then are made in response to immediate readout of product thickness and profile data thereby to minimize off-specification or scrap product. Provision also is made for pivoting one of the shoes and respective carriage clear of the extrudate path such as in the case of a jam-up.