| 摘要 |
PURPOSE:To prevent the generation of failures in appearance such as bank mark, sink mark, etc., by observing bank generated on the side of forming roll by use of a light source lighting the spot of bank forming at an acute angle and an optical fiber scope which is arranged between a die and a bank forming roll and controlling the amount of bank. CONSTITUTION:Thermoplastic resin is kneaded in a molding machine 1, extruded from a T-die 2, to pass through a first forming roll 3 and a second forming roll 4 and further passes a third forming roll 5 to become a sheet. In this case, a bank 6 is formed between the second forming roll and the extruded resin, and this bank 6 is observed by means of an optical fiber scope, wherein the roughness of the bank shows light and shade. Therefore, by repeating the adjusting operation of a choke bar depth adjusting bolt attached to the T-die and/or a lip divergence adjusting bolt, the height and the width of the bank are suppressed to less than the thickness of the sheet plate over the entire surface of the second forming roll, which is the bank forming roll, to unify the amount of the bank. In such a manner, a sheet excellent in precision of plate thickness and without failure in appearance is obtained and a safety operation is possible. |
