In-cycle dynamics of forming operations

Forming operations are commonly employed for the manufacturing of parts for the automotive, aeronautical, packaging, electronics and recreational sectors. Thermoforming is one such forming operation and is the process of choice for the manufacturing of hollow tub-shaped plastic parts such as car doors, signs, children pools and electronic housings. The absence of control of state parameters has been one of the major problems plaguing this process as material property changes, environmental factors, and machine operating drifts can significantly change the operating point of thermoforming machines. This paper focuses on the dynamics and in-cycle corrective control action of the sheet reheat stage in thermoforming, which is the most critical and difficult to control phase of the process. This is the first documented work that deals with the development of a model-based, feedback controller for the control of in-cycle dynamics in thermoforming.