Development of Die-lip Driving Mechanism Based on Elastic Deformation by Pneumatic Control

In the laminating process, automatic profile control of extruded film thickness in crossdirection is required for better productivity and product uniformity. The thickness profile is determined by the gap pattern of the die-lip heated at 350°C. Conventionally the correction of the gap is made by manual adjustment of the individual die bolts equipped in the side of the die. In this paper, a new method, which utilizes the mechanical elastic deformation of the lip by a pneumatic pressure control, is proposed with its construction and characteristic. Two bellows, which pressure is controlled with electro-pneumatic converter, are constructed in each zone of the die as actuators. As a result, the resolution of deformation 1.0 μm and the response time 0.4 s are obtained in heated condition. Additionally, a decoupling method for the model is proposed, in order to compensate the interactive deformation characteristic which is caused by continuum construction of the lip. Consequently, decoupling accuracy of 1% per full span and 0.6-1.0 μm resolution of deformation are obtained.