Method for thermoforming sheet articles

• US 5,928,597 A
• Filed: 10/09/1997
• Issued: 07/27/1999
• Est. Priority Date: 10/09/1997
• Status: Expired due to Fees

• Current Assignee: International Automotive Components Group North America (Lear Corporation)
• Original Assignee: Lear Corporation
• Inventors: Van Ert, Jack M.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): POE, MICHAEL I
• Application Number:
  US08/948,344
• Time in Patent Office: 656 Days
• Field of Search: 264/313, 264/314, 264/316, 156/583.3, 156/583.8, 156/222, 425/520, 425/521, 425/389, 425/390
• US Class Current: 264/316
• CPC Class Codes: B29C 2791/006 Using vacuum
• CPC Class Codes: B29C 33/20 Opening, closing or clamping
• CPC Class Codes: B29C 33/28 using hydraulic or pneumatic means
• CPC Class Codes: B29C 35/0227 using pressure vessels, e.g. autoclaves, vulcanising pans B29C35/065 takes precedence
• CPC Class Codes: B29C 43/36 Moulds for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B29C 51/082 by shaping between complementary mould parts
• CPC Class Codes: B29C 51/18 Thermoforming apparatus
• CPC Class Codes: B29C 51/30 Moulds
• CPC Class Codes: B29C 51/428 of moulds or mould parts
• CPC Class Codes: B29L 2031/3011 Roof linings
• CPC Class Codes: B30B 5/02 wherein the pressing means is in the form of a flexible element, e.g. diaphragm, urged by fluid pressure
• CPC Class Codes: B32B 37/1018 using only vacuum
• CPC Class Codes: B32B 38/12 Deep-drawing
• CPC Class Codes: B60R 13/0225 self supporting head liners
• CPC Class Codes: Y10T 156/1044 of parallel stacked sheets only

Abstract

A method of thermoforming sheet articles includes: a) heating a sheet article to be thermoformed; b) inserting the heated sheet article into a pressure vessel having first and second vessel halves, wherein each vessel half includes a liquid chamber and a thin shell configured for forming the sheet article to a desired shape; c) closing the pressure vessels such that the sheet article is captured between the thin shells; and d) providing liquid of equal pressure in each liquid chamber to force the thin shells together to form the sheet article to the desired shape and to draw heat away from the thin shells for cooling the sheet article.

Claims

1. A method of thermoforming a sheet article to a desired shape, comprising:

heating a sheet article to be thermoformed;

inserting the heated sheet article into a pressure vessel having first and second vessel halves, wherein each vessel half includes a fluid chamber and a thin, at least partially flexible shell, and the thin, at least partially flexible shells are configured to cooperate for reforming the sheet article to the desired shape;

closing the pressure vessel such that the sheet article is captured between the thin, at least partially flexible shells without completely reforming the article to the desired shape; and

providing fluid of equal pressure in each fluid chamber to force the thin, at least partially flexible shells together to completely reform the sheet article to the desired shape and to simultaneously draw heat away from the thin, at least partially flexible shells through the fluid for cooling the sheet article as the sheet article is reformed.

2. The method of claim 1, wherein said step of providing fluid of equal pressure in each fluid chamber comprises providing liquid in each fluid chamber at a pressure of less than 100 p.s.i.

3. The method of claim 2, wherein said step of providing liquid of equal pressure in each fluid chamber comprises communicating the fluid chambers to equalize pressure therebetween.

4. The method of claim 1, further comprising applying a cover material over the sheet article prior to said closing of the pressure vessel.

5. The method of claim 2, further comprising providing a plurality of light, hard fillers in one of said fluid chambers to reduce the volume of liquid in the respective vessel half for weight reduction to ease opening and closing of the vessel.

6. The method of claim 1, wherein said step of providing fluid comprises providing water.

7. The method of claim 1, wherein said step of closing the vessel comprises latching the vessel to allow pressurization.

8. The method of claim 1, further comprising providing a flexible diaphragm around the periphery of the thin shells to enable flexing of the thin shells as the pressure vessel is closed prior to providing fluid of equal pressure.