Method of Making Rolled Edge Trays
AssigneeConverter Manufacturing, LLC
InventorMillard F WALLACE
Life of this patent
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Abstract
The disclosure relates to forming shaped thermoplastic articles having smooth peripheries. Many thermoplastic articles have sharp edges formed upon molding or cutting the article from a feedstock sheet. Such sharp edges can damage thin plastic films or flesh which they contact, and smoothing the edges is desirable. Described herein are methods of forming a smooth periphery for such sharp-edged articles by rolling over the sharp edge. The smoothing operation is performed by forming a deflectable flange including a bend region separated from the potentially sharp peripheral edge by a spacer, deflecting a portion of the deflectable flange, and irreversibly bending, without heating, at least one bent portion of the deflectable flange to yield a smooth periphery upon cooling.
Claims13
A method of making a rounded rectangular tray that is smooth about its entire periphery, the method comprising
- forming a plastic material into a rounded rectangular body having a deflectable flange about its entire periphery,
- the deflectable flange comprising a spacer bearing a peripheral edge of the plastic material, the spacer being connected to the body by way of an extension that extends peripherally away from the body and a bend region interconnecting the spacer and the extension,
- the bend region having a smooth contour and interconnecting the spacer at an approximately right angle with the extension;
- after forming the plastic material into the body, impinging a ram against the deflectable flange without heating the plastic material to inwardly deflect the deflectable flange with sufficient force to irreversibly bend a portion of the plastic material, the portion being selected from the group consisting of the extension, the bend region, the spacer, and combinations of these;
- and
- disengaging the ram from the spacer, whereby the bent portion remains deflected from its pre-impingement position even upon discontinuation of the impingement to yield the body with a smooth periphery.
Dependencies are inferred from the claim text.