Real-time Toggle Clamping-mechanism Force Measurement and Melt Pressure Variation, and Its Effect on Injection Molded Part Weight

Abstract

Injection molding is one of the mainstream modern plastic processes. Proper molding methods are used based on the functional requirements of the product. As smart machinery and digital manufacturing evolve constantly, visualization by data acquisition and integration is becoming an inevitable topic, By installing sensors inside the mold, or even extending into the machine bed, variations of cavity pressure as well as relationships between the exertion of toggle mechanism force and product quality are further explored for achieving data integration and parameter adjustments accordingly. Taking a toggle clamping mechanism of an injection molding machine as the sensing subject, we performed analytical research and verified the weight changes of the product. Comparisons were made with sensor data acquired from molds and the tie bar of the molding system at the same time. Also, different parameters were used for researching the injection/packing process and the resulting stress-strain variations on the toggle mechanism (relevant processes include clamping force, injection speed, and packing switch-over position). The results show that(1) changes of sustained force are successfully sensed and monitored via a real-time sensor module installed on the toggle mechanism, (2) alterations of packing switch-over position, packing pressure as well as injection speed correlate to the toggle mechanism force variation and the melt filling pressure inside the cavity, and (3) toggle mechanism force variations observed positively correlate to product appearance and weight.