Parison Wall Thickness Profile And Its Control In Blow Molding Machine

Blow molding machine finds increasing applications in molding and processing of plastic products. The parison thickness control is one of the key parts of the blow molding machine. For a long time, this control system has been imported from foreign countries. To a great extent, it restricts the development of Chinese plastic machines. Based on the characteristic of parison wall thickness control in blow molding machine, this paper proposed a new algorithm to estimate the parison wall thickness profile, and developed a nonlinear PID controller for parison wall thickness control.In more detail, the algorithm for the estimation of the parison wall thickness profile is based on Bessel interpolation in combination with B-spline interpolation. The thickness profile is smooth enough, that overcomes the disadvantages of conventional B-spline interpolation. The nonlinear PID controller developed in this paper has been demonstrated to have a better control quality. The parison wall thickness controller uses PCC and POWER PANEL of B&R as hardware platform, which is programmable with C programming language. The minimum wall thicknesses was achieved with high accuracy and consistency by using micro-interpolating among set points. Therefore, material consumption was minimized.