Folded Plate

Capability in fabricating simple to complex folded products makes designing them easy based on analysis such as beams with rectangular, triangular, spherical, or other shapes. Products vary from those with spring actions to movable contoured walls and ceilings to botdes and outer-space structures. Elementary beam equations are used. When assemblies are plates whose lengdis are large relative to their cross-sectional dimensions (thin-wall beam sections, ribbed panels, and so on) and are in large plates whose fold lines deflcct identically, such as the interior bays of roofs or bridge structures, they can be analyzed as beams. More elaborate documented procedures are used to determine transverse multi-bending stresses in assemblies.

An example of folded plate technology are bellows-style collapsible plastic containers such as blow molded botdes that are foldable. The foldable shaped containers in contrast to that of the usual shaped bottles provides advantages and conveniences. Examples include reduced storage as the container's content is reduced, transportation volume and weight costs relate to the collapsed size, and disposal space; prolonged product freshness by reducing oxidation and loss of carbon dioxide; and provides extended life via continuous collapsing surface access to foods like mayonnaise and jams.

Figs 4.4 and 4.5 show the bellows of collapsible containers that overlap and fold to retain their folded condition without external assistance, thus providing a self-latching feature. The views show uncollapsed bottle, collapsed botde, and top view of the bottle. This latching is the result of bringing together under pressure two adjacent conical sections of unequal proportions and different angulations to the bottle axis. On a more technical analytical level the latching is created basically by the swing action of one conical section around a fixed pivot point, from an outer to an inner, resting position. The two symmetrically opposed pivot points and rotating segments keep a near-constant diameter as they travel along the bottle axis. This action explains the bowing action of the smaller, conical section as it approaches the overcentcring point.

Figure 4 1 Views of a collapsible bottle (Courtesy of Collapsible Bottle of America Co.)

Figure 4 1 Views of a collapsible bottle (Courtesy of Collapsible Bottle of America Co.)

75% Volume Redaction

Figure 4 Geometric concepts to the collapsible bottle (Courtesy of Collapsible Bottle of America Co.)

Figure 4 Geometric concepts to the collapsible bottle (Courtesy of Collapsible Bottle of America Co.)

Over 110° Angle Under 110° Angle

A characteristic in molding some products that are designed to include collapsing, living hinge, etc. action requires them to be subjected to the action as soon as possible after processing. This inidal action is used to create permanent fold rings and completely orient the plastic molecules. In most disposable applications these bottles would undergo three changes of volume: an initial collapsing of the container before shipment and storage; expansion of the container at its destination, before or during filling; and finally gradually collapsing the bottle for reuse or disposal.

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