Roll fed flotation/impingement air ovens and related thermoforming systems for corrugation-free heating and expanding of gas impregnated thermoplastic webs
First Claim
1. A method for generating microcellular bubbles in a thermoplastic material, the method comprising:
- conveying a thermoplastic material impregnated with a gas, through an oven chamber, wherein the thermoplastic material is continuously conveyed through the oven chamber; and
blowing air through at least two upwardly directed nozzles and at least two downwardly directed nozzles, toward the gas impregnated material inside the oven chamber, with the blowing air, heating the gas impregnated material, causing microcellular bubbles of gas in the material to nucleate and grow inside the material, while the material moves through the oven chamber, with only the blowing air, suspending the material while the material moves through the oven chamber and with only the blowing air, directing the material to undulate through at least two complete undulations as the material moves through the oven chamber and while microcellular bubbles nucleate and grow inside the material wherein impinging heated air streams from the at least two upwardly directed nozzles and at least two downwardly directed nozzles cause heating and uniform expansion of the gas impregnated material such that corrugation-free expansion of the gas impregnated material is enabled.
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Accused Products
Abstract
Disclosed herein are roll fed air heated flotation ovens and related thermoforming systems, assemblies, and machines that enable the corrugation-free expansion of a gas impregnated thermoplastic web passing through an oven chamber (without use of a pin-chain assembly), as well as to related methods. In an embodiment, a gas impregnated thermoplastic web is conveyed and expanded through an elongated air heated oven chamber, wherein the elongated oven chamber includes a plurality of downwardly directed heated air nozzles positioned at regular intervals along and within the upper portion of the oven chamber, and a plurality of upwardly directed heated air nozzles positioned at regular intervals along and within the lower portion of the oven chamber, but staggered apart from the downwardly directed heated air nozzles such that the gas impregnated thermoplastic material web undulates in an up and down wavelike fashion, thereby minimizing sagging, bagging, puckering, and/or buckling of the web.
135 Citations
15 Claims
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1. A method for generating microcellular bubbles in a thermoplastic material, the method comprising:
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conveying a thermoplastic material impregnated with a gas, through an oven chamber, wherein the thermoplastic material is continuously conveyed through the oven chamber; and blowing air through at least two upwardly directed nozzles and at least two downwardly directed nozzles, toward the gas impregnated material inside the oven chamber, with the blowing air, heating the gas impregnated material, causing microcellular bubbles of gas in the material to nucleate and grow inside the material, while the material moves through the oven chamber, with only the blowing air, suspending the material while the material moves through the oven chamber and with only the blowing air, directing the material to undulate through at least two complete undulations as the material moves through the oven chamber and while microcellular bubbles nucleate and grow inside the material wherein impinging heated air streams from the at least two upwardly directed nozzles and at least two downwardly directed nozzles cause heating and uniform expansion of the gas impregnated material such that corrugation-free expansion of the gas impregnated material is enabled. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification