Expanding process with non-aligned molds

• US 3,919,382 A
• Filed: 12/26/1973
• Issued: 11/11/1975
• Est. Priority Date: 12/29/1971
• Status: Expired due to Term

• Current Assignee: Walter H. Smarook
• Original Assignee: Walter H. Smarook
• Inventors: Smarook, Walter H.
• Primary Examiner(s): Anderson, Philip
• Application Number:
  US05/427,496
• Time in Patent Office: 685 Days
• Field of Search: 264/41,291,164,47,225,261 425/812,110 161/68,69,161
• US Class Current: 264/164
• CPC Class Codes: B29C 55/02 of plates or sheets
• CPC Class Codes: B29C 67/00 Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
• CPC Class Codes: B29D 99/0089 Producing honeycomb structures consisting of porous ceramic ware C04B38/0006
• CPC Class Codes: B32B 3/12 characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• CPC Class Codes: Y10S 425/812 Venting
• CPC Class Codes: Y10T 428/24149 Honeycomb-like
• CPC Class Codes: Y10T 428/24174 including sheet or component perpendicular to plane of web or sheet
• CPC Class Codes: Y10T 428/24298 Noncircular aperture [e.g., slit, diamond, rectangular, etc.]
• CPC Class Codes: Y10T 428/24322 Composite web or sheet

Abstract

A low pressure process for expanding the cross-section of a blank of thermoformable material between a pair of mold plates having perforation means therein, with the perforation means of one plate being selectively out of alignment, with the perforation means in a second plate, the expansion leading to the formation of one or more voids having a partial vacuum or reduced pressure within the cross-section of the blank, which comprises venting the voids during the expansion of the cross-section so as to equilibrate the level of pressure within the voids with the level of pressure without the blank so as to thereby regulate the uniformity and integrity of the resulting cross-sectional geometry of the expanded blank. Products having an expanded cross-section are formed by such process.

Claims

1. A PROCESS FOR EXPANDING THE CROSS SECTION OF A BLANK OF THEMOFROMABLE MATERIAL BETWEENA PAIR OF PERFOATION MEANS WHILE SAID BLANK IS IN A THERMOFORMABLE STATE, EACH SAID PERFORATION MEANS PROVIDING PERFORATIONS ADJACENT THE INTERFACE OF CONTACT BETWEEN SAID PERFORATIONS MEANS AND SAID BLANK, AND THE PERFORATIONS IN ONE PERFORATIONS MEANS BEING ON-ALIGNED WITH THE PERFORATIONS IN THE OTHE PERFORATION MEANS, SAID EXPANDIN BEING ATTENEDED BY THE FORMATION OF ONE OR MORE VOIDS HAVING A PARTIAL VACUUM THEREIN WITHIN THE CROSS SECTION OF THE EXPANDING BLANK, THE PATTERN OF OCCURRENC OF SUCH VOIDS BEING IN ESPONSE TO THE PATTERN OF PEFOATIONS IN SAID PEFORATION MEANS, WHICH COMPRISES VENING THE LOWE LEVEL OF PRESSURE WITHIN SAID AS TO EQUILIBRATE THE LOWER LEVEL OF PRESSURE WITHIN SAID VOIDS WITH THE HIGHE LEVEL OF AMBIENT PRESSURE WITHOUT SAID BLANK AND THEREBY REGULATE THE UNIFORMIY AND INTEGRITY OF THE RESULTING CROSS-SECTION GEOMETRY OF THE EXPANDED BLANK.

2. A process as in claim 1 in which the expansion of the cross section of the thermoformable material is accomplished by pulling the blank, while in said thermoformable state, between a pair of perforated mold plates as said perforation means.

3. A process as in claim 2 in which said blank is adhesively bonded to said mold plates during said pulling at the non-perforated areas of the perforated surfaces of the mold plates.

4. A process as in claim 3 in which said blank is adhesively bonded to said mold plates as a result of hot tack adhesion between said blank and the non-perforated surfaces of said mold plates.

5. A process as in claim 4 in which said blank comprises thermoplastic material.

6. A process as in claim 5 in which said thermoplastic material comprises synthetic resin.

7. A process as in claim 4 in which said blank comprises thermosetting resin.

8. A process for expanding the cross section of a material having a Ta between a pair of perforated mold plates while said material is in a thermoformable state so as to provide a product having an expanded cross-sectional geometry which comprises positioning said material between said mold plates while said material is heated to a temperature which is >

or = the Ta of said material, the perforations in each of said mold plates being non-aligned with the perforations in the other mold plate, adhesively bonding said material by hot tack adhesion to each of said mold plates at the non-perforated portions of the perforated surfaces of said mold plates, pulling said mold plates apart, while said material is so adhesively bonded thereto and is in said thermoformable state, so as to expand the cross section of said material and thereby effect within said material one or more voids having a partial vacuum therein, venting said voids during said pulling apart so as to equilibrate the lower level of pressure within said voids with the higher level of ambient pressure without said material and thereby preserve the pattern and the integrity of the voids in the resulting cross-sectional geometry, and cooling the expanded material to a temperature below the heat distortion point of said material.

9. A process as in claim 8 further comprising the separation of at least one of said mold plates from the cooled expanded material.

10. A process as in claim 8 in which each of the perforations in each of the mold plates overlaps at least one of the perforations in the other mold plate.

11. A process as in claim 10 in which the resulting cross-sectional geometry in the expanded material is a function of the pattern of said adhesion bonding.

12. A process as in claim 11 in which the perforations are all arcuate.

13. A process as in claim 11 in which the perforations are all angular.

14. A process as in claim 8 in which said venting is accomplished through said mold plates.

15. A process for expanding, between a pair of perforated mold plates, the cross section of a blank of material having a Ta while said blank is in a thermoformable state so as to provide the material with an expanded cross sectional geometry, which expanded geometry comprises a plurality of cells separated by expanded ribs of said material, and wherein the surface of each of said perforated mold plates has a non-perforated contacting surface area and said blank has two contacting surfaces, said process comprising positioning said mold plates with respect to each other so that the perforations therein are not aligned, positioning said blank between the surfaces of said mold plates while said blank is heated to a temperature which is >

or = said Ta, bringing said mold plates and said blank into contact at the contacting surfaces thereof while said blank is at a temperature of >

or = Ta so as to effect hot tack adhesion between said contacting surfaces, expanding the distance between said mold plates with said blank thus adhesively bonded thereto and while said blank is in said thermoformable state so as to effect an expansion of the cross-section of said blank with the attendant formation within said expaned cross-section of a plurality of cells separated by expanded ribs of the material in said blank, said cells encompassing areas having a partial vacuum therein, and the configuration of each, and of the combination of all, of said cells being in response to the pattern of contact between all of the contacting surfaces, venting said cells during said expansion so as to equilibrate the lower level of pressure within said cells with the higher level of ambient pressure without said blank and thereby maintain the uniformity and integrity of the configuration of the resulting cross sectional geometry, and cooling the expanded blank to a Temperature below the heat distortion of said material.

16. A process as in claim 15 in which each of the perforations in each of the mold plates overlaps at least one of the perforations in the other mold plate.

17. A process as in claim 16 in which all of the perforations are arcuate.

18. A process as in claim 16 in which all of the perforations are angular.

19. A process as in claim 15 in which said venting is accomplished through said mold plates.

20. A process as in claim 15 in which said blank is a sheet of said material having a Ta.

21. A process as in claim 15 in which the cross section of said blank is expanded >

or = 2 to 20 times the pre-expansion thickness of said blank.

22. A process as in claim 1 in which said perforation means is masking means.