Process control, e.g. for foamed particle molding, uses limits on measurements at a particular point within each cycle to initiate control action

摘要

An automatic process, e.g. for molding items from foamed particles, uses sensors to monitor process parameters, e.g. cylinder pressure (5) and tool displacement (4). Control action, such as stopping the process, is initiated when limits of parameter values are exceeded at particular point in process cycle. Limits are set initially, especially to prevent damage in hydraulic systems at certain positions of piston movement. An independent claim is also included for a control system with a memory function operating in this manner. In a foamed particle molding machine only values at the time of closing the mold are used, responding to a pressure discrepancy of less than 20 bar, to prevent mold closure when items formed in the previous cycle have not been ejected properly.