Compressing and shaping thermoformable mats using superheated steam
First Claim
1. A process of forming a porous, thermoformable mat into a desired shape and making the mat less flexible and resilient comprising the following steps:
- a) placing a porous thermoformable mat which can be formed and made less flexible and resilient by being heated under pressure to its thermoforming temperature between a pair of complementary, contoured dies, which, when brought fully together, define in a space between them a desired shape of the formed mat, each of said dies having a perforated contact surface and an enclosed chamber behind said contact surface, both said dies being preheated to an elevated temperature;
b) introducing superheated steam under pressure through a supply valve into the chamber of said first die while said mat is between said dies, so that the steam passes through the perforations in the first die'"'"'s contact surface and penetrates the mat, the pressure of the steam on the upstream side of the supply valve being at least about 30 psig, the temperature of the steam being high enough to heat the mat to its thermoforming temperature, and applying a vacuum to the chamber in the second die while the superheated steam is introduced to the chamber in the first die, so as to help pull the steam through the mat, the volume of said vacuum not substantially exceeding the volume of the steam introduced to the chamber in the first die;
c) bringing the dies fully together, thereby compressing the mat between the dies, said compressing occurring while the mat is at its thermoforming temperature;
d) halting the steam introduction;
e) maintaining the die compression on said mat until the mat is substantially completely thermoformed into the desired shape;
f) separating said dies after the mat is substantially completely thermoformed; and
g) removing the mat from between said dies.
2 Assignments
0 Petitions
Accused Products
Abstract
A thermoformable mat, e.g., a mat of resinated fiberglass, is compressed and shaped into a contoured object, e.g., a shell for an automobile headliner, by this process. The mat is compressed between two dies that have been preheated. At least one of the dies is perforated. Superheated steam (e.g., at 80 psig and 600° F.) is ejected from the perforations into the mat, thereby quickly raising the mat temperature to its thermoforming point. After the mat is set into the contoured shape, the dies are reopened and the formed mat is removed. If the mat that is used contains a thermoplastic adhesive, the mat is cooled to below the adhesive'"'"'s melt print before the dies are opened. This can be done by applying a vacuum to the perforated die and pulling ambient air through the mat.
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Citations
44 Claims
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1. A process of forming a porous, thermoformable mat into a desired shape and making the mat less flexible and resilient comprising the following steps:
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a) placing a porous thermoformable mat which can be formed and made less flexible and resilient by being heated under pressure to its thermoforming temperature between a pair of complementary, contoured dies, which, when brought fully together, define in a space between them a desired shape of the formed mat, each of said dies having a perforated contact surface and an enclosed chamber behind said contact surface, both said dies being preheated to an elevated temperature; b) introducing superheated steam under pressure through a supply valve into the chamber of said first die while said mat is between said dies, so that the steam passes through the perforations in the first die'"'"'s contact surface and penetrates the mat, the pressure of the steam on the upstream side of the supply valve being at least about 30 psig, the temperature of the steam being high enough to heat the mat to its thermoforming temperature, and applying a vacuum to the chamber in the second die while the superheated steam is introduced to the chamber in the first die, so as to help pull the steam through the mat, the volume of said vacuum not substantially exceeding the volume of the steam introduced to the chamber in the first die; c) bringing the dies fully together, thereby compressing the mat between the dies, said compressing occurring while the mat is at its thermoforming temperature; d) halting the steam introduction; e) maintaining the die compression on said mat until the mat is substantially completely thermoformed into the desired shape; f) separating said dies after the mat is substantially completely thermoformed; and g) removing the mat from between said dies. - View Dependent Claims (19, 20, 21, 22, 25, 38, 41, 42)
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2. A process of forming into a desired shape and making less flexible and resilient a porous, thermoformable mat comprised of substrate material intermixed with a heat activatable adhesive that is capable, upon being activated and then set, of holding the substrate material in a contoured shape and making the mat less flexible and resilient, comprising the following steps:
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a) placing the mat between a pair of complementary, contoured dies which, when brought fully together, define in a space between them a desired shape of the formed mat, each of said dies having a perforated contact surface and an enclosed chamber behind said contact surface, both said dies being preheated to an elevated temperature; b) introducing superheated steam under pressure through a supply valve into the chamber of said first die while said mat is between said dies, so that the steam passes through the perforations in the first die'"'"'s contact surface and penetrates the mat, the pressure of said steam on the upstream side of the supply valve being at least about 30 psig, the temperature of the steam being high enough to heat the adhesive to its activation temperature, and applying a vacuum to the chamber in the second die while the superheated steam is introduced to the chamber in the first die, so as to help pull the steam through the mat, the volume of said vacuum not substantially exceeding the volume of the steam introduced to the chamber in the first die; c) bringing the dies fully together, thereby compressing the mat between the dies, said compressing occurring while the adhesive is at activation temperature and commencing before the adhesive has set; d) halting the steam introduction; e) maintaining the die compression on said mat until the adhesive is substantially set; f) separating said dies after the adhesive is substantially set; and g) removing the mat from between said dies. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 39, 40, 43, 44)
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Specification