On-line monitoring methodology for die forging quality based on the piezoelectric effect

Forging forming defects and machine failures are often caused by changes of forging force in the forging forming process. Tonnage signals contains significant amount of real-time forming information, by which the forging forming on-line monitoring system is developed. Tonnage signals produced by forging force are collected based on the principle of piezoelectric effect. The charge amplifier circuit is designed to achieve impedance matching and the envelope curves are exacted using envelope detector circuit. By identifying profile changes of envelope curves, forming quality is classified. Median filtering methodology is applied to establish the standard waveform and fault-tolerance zone, while a methodology is developed to establish quality identification function and ultimately to on-line monitor forging forming quality. The application object of the design is the steel ball cold head machine.