APPARATUS OF VACUUM FORMING

• US 3,779,687 A
• Filed: 05/14/1970
• Issued: 12/18/1973
• Est. Priority Date: 05/14/1970
• Status: Expired due to Term

• Current Assignee: John A. Alesi
• Original Assignee: John A. Alesi
• Inventors: Alesi, John A.
• Primary Examiner(s): Flint, Jr., J. Howard
• Application Number:
  US05/048,722
• Time in Patent Office: 1,314 Days
• Field of Search: 425/340,341,342,388,346,383,384,404 264/90,92
• US Class Current: 425/383
• CPC Class Codes: B29C 43/12 using bags surrounding the moulding material or using membranes contacting the moulding material
• CPC Class Codes: B29C 51/18 Thermoforming apparatus
• CPC Class Codes: B29C 51/267 Two sheets being thermoformed in separate mould parts and joined together while still in the mould B29C49/0691 takes precedence
• CPC Class Codes: B29C 51/28 for applying pressure through the wall of an inflated bag or diaphragm

Abstract

Apparatus for forming first and second sheets of heat-fusible plastic into a hollow structure when the sheets are heated to an initial temperature and mechanically prestretched into the cavities of first and second mold members. Vacuum is then applied between each of the sheets and such mold cavities to draw the sheets into their formed configuration. The sheets are then reheated to a higher temperature and the mold members urged together to effect fusing engagement of the sheets.

Claims

1. Apparatus for forming first and second sheets of heat-fusible plastic into a hollow structure, comprising:

a frame;

first and second support members that releasably support the edges of said sheets;

heating means for said sheets;

first and second mold members, each having complementary edges and formed inwardly of said edges with mold cavities that cooperate to define the shape of said hollow structure, said mold members being movably mounted on said frame for movement between a horizontally-extending spaced-apart position to a vertically-extending facing position;

power-operated means on said frame for moving said mold members between said positions;

means for applying a vacuum between said sheets and their respective mold cavities to draw said sheets into said mold cavities;

transfer means on said frame carrying said support members for first moving said sheets between said heating means and thereafter into a position over said mold members;

second power-operated means on said frame for urging said mold members together while said mold members are disposed in said vertically-extending facing position to thereby cause said edges to apply mechanical pressure to the portions of said sheets adjacent said edges whereby said sheet portions are fused together;

auxiliary heating means; and

means on said frame for moving said auxiliary heating means into the space between said mold members when the latter are disposed in their vertically-extending facing position to thereby apply fusing heat to said plastic sheets, with said last-mentioned means moving said auxiliary heating means out of said space before said mold members are urged together.

2. Apparatus as set forth in claim 1 whErein said heating means include upper and lower vertically-spaced heating elements, with said sheets being disposed therebetween for heating.

3. Apparatus as set forth in claim 1 and further comprising means for mechanically prestretching each of said sheets, said prestretching means including a plug having a profile complementary to its respective mold cavity.

4. Apparatus as set forth in claim 2 and further comprising means for mechanically prestretching each of said sheets, said prestretching means including a plug having a profile complementary to its respective mold cavity.