| 摘要 |
An arrangement for adjusting the mass of gobs of thermoplastic material, especially molten glass, which are deformed in a positive manner in the mold of a molding machine by means of a pressing member which penetrates into the gobs. A distance transducer mechanically detects the maximum depth of penetration reached by the pressing member during each molding-machine operating cycle. The distance transducer is connected with a metallic actuating element for a differential transducer, at whose output is produced an electrical signal proportional to the maximum penetration depth reached, this signal being applied to an automatic regulating circuit which adjusts the setting of a dosing structure which controls the mass of the gobs. The regulating circuit includes, at the output of the differential transformer and connected one after the next, a measurement transducer, a maximum-value storage, a sample-and-hold circuit, a summing junction, a PI- or PID-regulator and an adjusting motor which drives an adjusting member for the dosing structure, as well as a feedback transducer. The feedback transducer is connected to the PI- or PID-regulator via a rotary-angle-to-voltage converter. A control and display panel is connected to a control logic circuit, the latter connected to the maximum-value storage and to the sample-and-hold circuit, the control logic circuit receiving a machine synchronization signal once per machine operating cycle. A desired-value potentiometer furnishes a desired-value voltage representing the optimum penetration depth for the pressing member, this voltage being applied to the summing junction. A weighting circuit can be provided to take into account the different maximum diameters of different pressing members which may from time to time be used. The feedback transducer is automatically returned to a middle angular setting thereof. The distance transducer can be constructed in several different ways, disclosed. |
