| 摘要 |
Different ways are disclosed for manufacturing air cell dunnage in which the variation in thickness of the individual bubble walls is significantly reduced. In one embodiment, the bubbles are formed from a plastic sheet having regions which vary in thickness so that when these regions are vacuum formed into bubbles, they result in bubbles having an approximately uniform wall thickness. The sheets are extruded through a die which is shaped to profile the thickness of the sheet from side to side. Longitudinal profiling of the thickness is provided by means of shaping bars which move vertically with respect to the extruded sheet.The variation in wall thickness also can be reduced using flat plastic sheet by controlling the application of the vacuum to the hemispherical dies which form the bubbles. The vacuum may be applied progressively through rings of apertures from the bottom or opening of the bubble to the top or apex of the bubble. Alternatively, the suction applied to the various rings of apertures in the hemispherical dies can be varied, with greater suction applied at the base and less suction at the top, again for the purpose of increasing stretching at the base and reducing it at the top. |
