Packaging tray and method of manufacture
Thermoplastic packaging trays are provided that are filled with a product and wrapped in film, and methods of producing the tray with a peripheral edge region that avoids tearing of the overwrap film. In various embodiments, the tray has a beaded, a flat, or a combined beaded and flat peripheral edge.
1. A method of producing a plastic packaging tray having a peripheral edge region terminating in a terminal edge that is displaced out of a wrap path around the tray, the method comprising:
providing a thermoformed plastic intermediate article for forming the tray, the intermediate article having a peripheral flange;
stretching the peripheral flange;
while the peripheral flange is stretched, cutting off an outermost portion of the peripheral flange to form the terminal edge; and
cold pressing the peripheral flange of the intermediate article by bringing a compressing tool into engagement with the peripheral flange to displace the terminal edge out of the wrap path, the cold pressing step including permanently deforming the peripheral flange.
2. The method of claim 1 , wherein the cold pressing step further comprises forming a bead at an outermost periphery of the tray.
3. The method of claim 2 , wherein the cold pressing step further comprises selecting a degree by which the compressing tool displaces the terminal edge in order to select an extent of fully or partially closing the bead, to form a compressed bead at the outermost periphery of the tray having a selected outer surface area for engagement with a wrap film disposed within the wrap path.
4. The method of claim 3 , wherein the degree by which the compressing tool displaces the terminal edge produces a partially closed compressed bead at the outermost periphery.
5. The method of claim 3 , wherein the degree by which the compressing tool displaces the terminal edge produces a fully closed compressed bead at the outermost periphery of the tray.
6. The method of claim 2 , wherein the outermost periphery of the tray is rectangular shaped with rounded corners.
7. The method of claim 1 , wherein the cold pressing step further comprises forming a partially closed bead at an outermost periphery of the tray.
8. The method of claim 1 , wherein the cold pressing step further comprises forming a fully closed bead at an outermost periphery of the tray.
9. The method of claim 1 , wherein the cold pressing step further comprises forming a beaded edge comprising (a) a bead at an outermost periphery of the tray, and (b) a tail leg extending between the bead and the terminal edge.
10. The method of claim 1 , wherein the step of cutting off the outermost portion of the peripheral flange comprises producing an article having an outermost periphery which is rectangular shaped with rounded corners.
11. The method of claim 1 , wherein the step of cutting off the outermost portion of the peripheral flange comprises cutting the peripheral flange at a location that leaves the terminal edge inward from an outermost periphery of the tray.
12. The method of claim 1 , wherein the cold pressing step includes permanently deforming the peripheral flange past its elastic limit.
13. An apparatus for producing a plastic packaging tray having a peripheral edge region terminating in a terminal edge that is displaced out of a wrap path around the tray, the apparatus comprising:
a cutting tool configured to stretch a peripheral flange of a thermoformed plastic intermediate article, the cutting tool being further configured to form the terminal edge by cutting off an outermost portion of the peripheral flange while the peripheral flange is stretched; and
a first edge-forming tool configured to cold press the peripheral flange of the intermediate article, the first edge-forming tool comprising a surface arranged to engage with the peripheral flange to displace the terminal edge out of the wrap path, the first edge-forming tool being further configured to permanently deform the peripheral flange.
14. The apparatus of claim 13 , wherein the surface of the first edge-forming tool is configured to form a bead at an outermost periphery of the tray.
15. The apparatus of claim 14 , wherein the first edge-forming tool is further configured to select a degree by which the first edge-forming tool displaces the terminal edge in order to select an extent of fully or partially closing the bead.
16. The apparatus of claim 13 , wherein the first edge-forming tool is further configured to form a partially closed bead at an outermost periphery of the tray.
17. The apparatus of claim 13 , wherein the first edge-forming tool is further configured to form a fully closed bead at an outermost periphery of the tray.
18. The apparatus of claim 13 , wherein the first edge-forming tool is further configured to form a beaded edge comprising (a) a bead at an outermost periphery of the tray, and (b) a tail leg extending between the bead and the terminal edge.
19. The apparatus of claim 13 , further comprising a second edge-forming tool configured to hold the thermoformed plastic intermediate article while the peripheral flange is being cold pressed between the first and second edge-forming tools.
20. The apparatus of claim 13 , wherein the second edge-forming tool is configured to hold an intermediate article having an outermost periphery which is rectangular shaped with rounded corners.
21. The apparatus of claim 13 , wherein the cutting tool is configured to cut the peripheral flange at a location that leaves the terminal edge inward from an outermost periphery of the tray.
22. The apparatus of claim 13 , wherein the first edge-forming tool is configured to permanently deform the peripheral flange past its elastic limit.