TWIN SHEET THERMOFORMER

• US 3,868,209 A
• Filed: 02/22/1973
• Issued: 02/25/1975
• Est. Priority Date: 02/22/1973
• Status: Expired due to Term

• Current Assignee: John Brown Industries Limited
• Original Assignee: George H. Howell
• Inventors: Howell, George H.
• Primary Examiner(s): Spicer, Jr., Robert L.
• Application Number:
  US05/334,841
• Time in Patent Office: 733 Days
• Field of Search: 264/92,97 425/109,162,387,157,388,160,343,408,504,453
• US Class Current: 425/504
• CPC Class Codes: B29C 2043/3411 mounted onto arms, e.g. grippers, fingers, clamping frame, suction means
• CPC Class Codes: B29C 43/34 Feeding the material to the mould or the compression means B29C43/085 takes precedence
• 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

Abstract

Apparatus and methods for fabricating a hollow plastic object from a pair of heat-fusible, thermoplastic sheets which are serially moved in a common horizontal plane from a heating station to a mold mechanism at a forming station. At the forming station, one of the sheets is received by a mold which is then moved vertically to move the sheet out of the plane to a position juxtaposed with a following sheet when the latter arrives at the forming station. At least one of the sheets is differential pressure molded after arrival at the forming station and the sheets are then vertically moved together and fused to form the object.

Claims

1. Apparatus for forming hollow thermoplastic objects from first and second thermoplastic sheets comprising:

a first and a second carriage means for releasably clamping respective first and second thermoplastic sheets thereon, indexing means supporting each of said first and second carriage means for step-by-step movement to a series of successive work stations disposed along an endless path with said first carriage means maintained one step of movement in advance of said second carriage means, said work stations including a sheet transfer station, at least one heating station and a forming station, a pair of opposed mold members mounted on opposite sides of said endless path at said forming station for movement between a normally maintained spaced apart mold open position and a clampingly engaged mold closed position, means creating a sheet molding differential pressure in at least one of said mold members, first means operable upon the arrival of said first carriage means at said forming station for releasing a first sheet carried by said first carriage means from said first carriage means and transferring it to one of said mold members, and for actuating said indexing means to advance said first carriage means from said forming station while simultaneously advancing said second carriage means with a second sheet thereon to said forming station, second means operable upon the arrival of said second carriage means at said forming station to shift said mold members to said closed position to fuse said sheets And thereby form said object while said second sheet is retained by said second carriage means, and third means operable upon the formation of said object to restore said mold members to said open position and to actuate said indexing means to advance said second carriage means from said forming station with the formed object supported thereon.

2. Apparatus as defined in claim 1 wherein said transfer station comprises a load-unload station and said first and second carriage means are advanced successively from said forming station to said load-unload station, and loading means provided at said load-unload station operable to load a first sheet onto said first carriage means while said second carriage means is located at said forming station.

3. Apparatus as defined in claim 2 further comprising means for actuating said loading means to load a second sheet onto said second carriage means subsequent to the unloading of a formed object therefrom.

4. Apparatus as defined in claim 1 wherein said first means comprises first power means operable upon the arrival of said first carriage means at said forming station for shifting said one mold member only from its open position into engagement with the first sheet on said first carriage means and responsive to the release of said first sheet from said first carriage means to said one mold member for returning said one mold member to its open position with said first sheet.

5. Apparatus as defined in claim 1 wherein said second means comprises second power means operable upon the arrival of said second carriage means at said forming station for shifting said other mold member to its mold closed position in engagement with the second sheet on said second carriage means, said differential pressure creating means forms said second sheet to the conformation of said other mold member, and means is provided for subsequently shifting said one mold member to its mold closed position.

6. Apparatus as defined in claim 1 wherein said differential pressure creating means conforms said first sheet to said first mold member prior to the arrival of said second carriage means at said forming station.