| 摘要 |
PURPOSE:To minimize the consumption of resin at an optimum thickness and to improve appearance and strength by a method wherein master points are set at a plurality of points of change in thickness of a parison and interpolations among them are performed by means of a spline interpolation method to make a pattern wherein the max or the min. values becomes a limiting value and the position of a core is controlled by obtaining an aimed value on the thickness at a cycle point at every n-section of a molding cycle time. CONSTITUTION:When a product 40 is aimed, at first, a plurality of master points mp1-mp10 are set on a curved part exhibiting the aimed change in thickness of a parison and interpolation between each interval is performed by means of a spline interpolation method to obtain a dotted line curve B. Then, correction is done by performing an interpolation wherein the max. and the min. values of the master points are limiting values to obtain a continuous line smooth curve A. An aimed value of thickness corresponding to each cycle point set at every n-section time of a molding cycle time is calculated from this pattern. Then, a stroke of a core is calculated from this aimed value of the thickness and a hydraulic cylinder is controlled by using a signal output at each cycle point and the core is moved so as to obtain a given stroke. |
