Rotatable sheet support structure for a twin-sheet thermoformer

• US 5,975,879 A
• Filed: 09/30/1997
• Issued: 11/02/1999
• Est. Priority Date: 09/30/1997
• Status: Expired due to Term

• Current Assignee: Trienda Holdings, L.L.C. (Kruger Family Industries, LLC)
• Original Assignee: Alltrista Corporation (Newell Brands Inc.)
• Inventors: Dresen, William L., Hart, James P.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): LEE, DAE Y
• Application Number:
  US08/940,625
• Time in Patent Office: 763 Days
• Field of Search: 425/388, 425/397, 425/DIG. 48, 425/504, 425/508, 264/297.3, 264/297.5, 264/297.6, 264/544, 264/545
• US Class Current: 425/504
• CPC Class Codes: B29C 2949/3094 preform having at least partially loose components, e.g. at least partially loose layers
• CPC Class Codes: B29C 43/203 Making multilayered articles
• CPC Class Codes: B29C 49/0691 using sheet like material, e.g. sheet blow-moulding from joined sheets
• CPC Class Codes: B29C 51/082 by shaping between complementary mould parts
• CPC Class Codes: B29C 51/10 Forming by pressure difference, e.g. vacuum
• CPC Class Codes: B29C 51/14 using multilayered preforms or sheets
• CPC Class Codes: B29C 51/22 rotatable about an axis
• CPC Class Codes: B29L 2009/001 the layers being loose

Abstract

Multiple legs elevate a central ring bearing, to which a ring-shaped rotatable plastic sheet support carousel is mounted. The carousel is fitted with a ring gear which engages with a drive system to position the carousel and the thermoplastic sheets supported from it. A multi-post vertical press is positioned with two posts extending upwardly interior to the ring bearing, and two posts extending upwardly exterior to the ring bearing. The ring bearing thus extends through the press, allowing the carousel to supply and remove plastic sheets to and from the press. An upper platen and a lower platen are mounted for vertical displacement to the posts, thereby ensuring a high degree of parallelism between the molds mounted to the platens, and accurate twin-sheet thermoforming.

Claims

1. A sheet carrying support structure for supporting thermoplastic sheets in a twin-sheet thermoforming apparatus, the support structure comprising:

an elevated ring bearing having a fixed portion and a rotatable portion; and

a rotatable carousel having a plurality of sheet-receiving openings, the carousel being supportive of at least a first thermoplastic sheet and a second thermoplastic sheets, the carousel being fixed to the rotatable portion of the ring bearing and supported on the ring bearing, the carousel defining an interior opening trough which at least one interior vertical post of a vertical press may extend, and having an exterior perimeter which extends between the at least one interior vertical post and a plurality of exterior posts of a vertical press, the carousel and the rotatable portion of the ring bearing being rotatable as a single element and supported entirely on the ring bearing fixed portion.

3. The sheet carrying support structure of claim 1 wherein the carousel comprises:

an inner ring connected to the ring bearing;

an outer ring larger in diameter than the inner ring; and

a plurality of members extending between and connecting the inner ring and the outer ring, wherein a plurality of openings for rectangular thermoplastic sheets are defined between the members and the inner ring and the outer ring.

4. The sheet carrying support structure of claim 1 wherein the ring bearing is elevated above a support surface on a plurality of vertically extending legs.

2. A sheet carrying support structure for supporting thermoplastic sheets in a twin-sheet thermoforming apparatus the support structure comprising:

an elevated ring bearing; and

a rotatable carousel which supports at least a first thermoplastic sheet and a second thermoplastic sheet the carousel being rotatably mounted on the ring bearing, the carousel defining an interior opening through which at least one interior vertical post of a vertical press may extend, and having an exterior perimeter which extends between the at least one interior vertical post and a plurality of exterior posts of a vertical press, wherein the carousel is supported entirely on the elevated ring bearing, the carousel having radially outwardly extending portions which are cantilevered outwardly from the ring bearing.

5. A sheet carrying support structure for supporting thermoplastic sheets for displacement within a twin-sheet thermoforming apparatus, the support structure comprising:

a support frame elevated above a support surface on a plurality of legs;

an inner ring mounted for rotation to the support frame and supported entirely on the support frame, the inner ring being toothed to permit the inner ring to be driven; and

members which extend radially outwardly from the inner ring to define a plurality of sheet receiving openings, wherein an inner ring interior is defined within the inner ring which is large enough to receive at least one interior vertically extending post of a vertical press, and wherein the radially outwardly extending members are sufficiently short that they do not engage a plurality of exterior posts of said vertical press, so that thermoplastic sheets supported on the radially extending members are rotatable on the support Frame without interference with the vertical posts of said vertical press, the radially extending member being supported entirely on the inner ring.

7. The sheet carrying support structure of claim 5 wherein the inner ring is mounted by a ring bearing to the support frame.

8. The sheet carrying support structure of claim 5 wherein the diameter of the inner ring is sufficiently large to admit two vertical posts of a vertical press within the inner ring interior.

9. The sheet carrying support structure of claim 5 wherein four sheet receiving openings are defined exterior to the inner ring, each sheet receiving opening being substantially rectangular and positioned approximately ninety degrees from the adjacent sheet receiving openings.

6. A sheet carrying support structure for supporting thermoplastic sheets for displacement within a twin-sheet thermoforming apparatus, the support structure comprising:

a support frame elevated above a support surface on a plurality of legs;

an inner ring mounted for rotation to the support frame; and

members which extend radially outwardly from the inner ring to define a plurality of sheet receiving openings, wherein an inner ring interior is defined within the inner ring which is large enough to receive at least one interior vertically extending post of a vertical press, and wherein the radially outwardly extending members are sufficiently short that they do not engage a plurality of exterior posts of said vertical press, so that thermoplastic sheets supported on the radially extending members are rotatable on the support frame without interference with the vertical posts of said vertical press, wherein the radially extending members are entirely supported by engagement of the ring on the support frame.

10. A sheet carrying support structure for advancing thermoplastic sheets between an upper mold and a lower mold mounted to an upper platen and a lower platen respectively of a vertical press having at least one interior vertical post and two exterior vertical posts with the upper platen and lower platen mounted to the posts, the sheet carrying support structure comprising:

an inner ring which is toothed to permit the inner ring to be driven;

an outer ring fixed to the inner ring by a plurality of members to define a plurality of sheet receiving openings defined between the inner ring and the outer ring;

a frame to which the inner ring is mounted, wherein the frame elevates the inner ring and the outer ring to be below the lowest position of the upper platen and above the highest position of the lower platen; and

means for mounting the inner ring to the frame for rotatable displacement, wherein the vertical press at least one interior vertical post is positioned within the inner ring, and the vertical press two exterior vertical posts are positioned exterior to the inner ring and the outer ring, the rotatable displacement of the inner ring bringing each sheet receiving opening between the upper platen and the lower platen and the molds mounted thereon for vertical displacement of the molds to mold thermoplastic sheets supported within the sheet receiving openings the inner ring and the outer ring being supported entirely on the frame.

11. A sheet carrying support structure for advancing thermoplastic sheets between an upper mold and a lower mold mounted to an upper platen and a lower platen respectively of a vertical press having at least one interior vertical post and two exterior vertical posts with the upper platen and lower platen mounted to the posts, the sheet carrying support structure comprising:

an inner ring;

an outer ring connected to the inner ring;

a plurality of sheet receiving openings defined between the inner ring and the outer ring;

a frame to which the inner ring is mounted, wherein the frame elevates the inner ring and the outer ring to be below the lowest position of the upper platen and above the highest position of the lower platen; and

means for mounting the inner ring to the frame for rotatable displacement, wherein the vertical press at least one interior vertical post is positioned within the inner ring, and the vertical press two exterior vertical posts are positioned exterior to the inner ring and the outer ring, the rotatable displacement of the inner ring bringing each sheet receiving opening between the upper platen and the lower platen and the molds mounted thereon for vertical displacement of the molds to mold thermoplastic sheets supported within the sheet receiving openings, wherein the outer ring and the inner ring are entirely supported on the frame.

12. A sheet carrying support structure and molding station for supporting and forming thermoplastic sheets in a twin-sheet thermoforming apparatus, comprising:

an elevated ring bearing, the ring bearing being a recirculating ball bearing assembly, having a rotatable upper portion; and

a vertical press having a plurality of parallel vertical posts, the press having a lower platen mounted to the posts and an upper platen mounted to the posts above the lower platen, the upper platen and lower platen being mounted to the posts to allow the parallel closing of an upper mold mounted to the upper platen on a lower mold mounted to the lower platen; and

a rotatable carousel which supports at least a first thermoplastic sheet and a second thermoplastic sheet, the carousel being fixed to the ring bearing rotatable upper portion and supported entirely thereon, the carousel defining an interior opening through which at least one interior vertil post of the vertical press extends, and having an exterior perimeter which extends between the at least one interior vertical post and a plurality of exterior posts of the vertical press.

13. The apparatus of claim 12 wherein the press has two interior posts which extend upwardly through the interior opening of the carousel, and two exterior posts which extend vertically exterior to the carousel.

14. The apparatus of claim 13 wherein the horizontal distance between the two interior posts of the press is less than the horizontal distance between the two exterior posts of the press.