| 摘要 |
PURPOSE:To make the wall thickness of a formed item uniform while preventing wrinkles from developing by a method wherein clamps are shifted inwards and simultaneously adjoining clamps are brought close to each other by a shifting means, which does not utilize the sliding-in of a forming sheet stock. CONSTITUTION:The setting of holding positions of clamps are done by the method wherein the clamps 8 is arranged above the below the edges of all the sides of a forming sheet stock 10 through expansion and contraction of expansion clamps 14, which are done by shifting floating plates 13 through the approach and separation of two pairs of two rails 12a and 12c and 12b and 12d opposing to each other developed by the rotation of four feed shafts 11. Next, the forming sheet stock 10 is heated and softened with a heating device. After that, a movable mold 4 is moved downwards, the softened forming sheet stock 10 is allowed to slide in a clearance 5 by the weight of itself. At that time, the expansion clamps 14 of all the sides or of two sides opposite to each other are brought near to one another so as to control the sliding-in speed of the forming sheet stock 10 in order to effectively prevent wrinkles from developing. |
