Product portioning in the continuous pumping of plastic materials

摘要

A viscous products pumping machine meters the volume of product that it dispenses by simultaneously displacing a proportionate amount of fluid through a separate metering circuit. The fluid of the metering circuit also serves as the medium for driving the pumping pistons of the machine, and provision is made for obtaining an accurate measurement notwithstanding any product of fluid leakage that might occur between the pistons during operation. A pneumatic logic control system governs sequencing of the machine operations, including control of a shut-off valve in the product discharge line that can be used to portion the pumped product according to the amount of fluid that has been displaced in the metering circuit.