Fabricating apparatus for twin-sheets

• US 3,925,140 A
• Filed: 03/16/1973
• Issued: 12/09/1975
• Est. Priority Date: 03/16/1973
• Status: Expired due to Term

• Current Assignee: John Brown Industries Limited
• Original Assignee: Leesona Corp.
• Inventors: Brown, Gaylord W.
• Primary Examiner(s): Weston, Caleb
• Application Number:
  US05/341,850
• Time in Patent Office: 998 Days
• Field of Search: 156/285,382,362,363,364,366,499,500,358,359 425/185,383,384,388,156
• US Class Current: 156/382
• 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 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 65/18 using heated tools
• CPC Class Codes: B29C 66/54 Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles
• CPC Class Codes: B29C 66/82421 using an inflatable element positioned between the joining tool and a backing-up part
• CPC Class Codes: B29C 66/8322 Joining or pressing tools reciprocating along one axis

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 OBJECTS FROM FIRST AND SECOND THERMOPLASTIC SHEETS WHEREIN THE AMOUNT OF HEAT REQUIRED TO BRING A FIRST SHEET TO ITS FORMING TEMPERATURES DIFFERS SUBSTATIALLY FROM THE AMOUNT OF HEAT REQUIRED TO BRING A SECOND SHEET TO ITS FORMING TEMPERATURE , SAID APPARATUS COMPRISING HEATING MEANS, DIFFERENTIAL PRESSURE, SAID APPARATUS COMPRISLOCATED AT A FORMING STATION ADJACENR SAID HEATING MEANS, CARRIER MEANS FOR ADVANCING FIRST AND SECOND SHEETS IN UNIFORMLY SPACED ALTERNATE SUCCESSION IN INTERMITTEN STEP-BY STEP MOVEMENT ALONG A FIXED PATH WITH EACH FIRST SHEET BEING LOCATED ONE STEP IN ADVANCE OF A SECOND SHEET, SAID CARRIER MEANS CARRYING SAID SHEETS IN SUCCESSION INTO OPERATIVE RELATIONSHIP WITH SAID HEATING MEANS AND SUBSEQUENTLY ADVANCING SAID SHEETS IN SUCCESSION INTO OPERATIVE RELATIONSHIP WITH SAID FORMING MEANS AT SAID FORMING STATION WHILE PAUSING FOR A PREDETERMINED TIME INTERVAL BETWEEN SUCCESSIVE STEPS OF MOVEMENT TO ACCOMODATE HEATING AND FORMING OF SAID SHEETS WHILE SAID SHEETS ARE AT SAID HEATING MEANS AND FORMING STATION, MEANS AT SAID FROMING STATION OPERABLE ON ALTERNATE STEPS OF MOVEMENT OF SAID CARRIER MEANS TO TRANSFER A FIRST SHEET FROM SAID CARRIER MEANS TO SAID FORMING MEANS WITHIN SAID PREDETERMINED TIME INTERVAL BETWEEN A FIRST STEP OF MOVEMENT OF SAID CARRIER MEANS AND ITS NEXT STEP OF MOVEMENT AND OPERABLE AFTER SAID NEXT OF MOVEMENT OF SAID CARRIER MEANS ADVANCES A SECOND SHEET INTO OPERATIVE RELATIONSHIP WITH SAID FORMING MEANS TO ACTUATE SAID FORMING MEANS TO FORM SAID OBJECT WITHIN THE PREDETERMINED TIME INTERVAL BETWEEN SAID NEXT STEP OF MOVEMENT AND THE NEXT SUBSEQUENT STEP OF MOVEMENT, AND FIRST HEATER CONTROL MEANS RESPONSIVE TO THE ARRIVAL OF A FIRST SHEET AT SAID HEATING MEANS FOR OPERATION SAID HEATING MEANS TO SUPPLY A FIRST AMOUNT OF HEAT TO SAID FIRST SHEET WITHIN SAID PREDETERMINED TIME INTERVAL AND RESPONSVE TO THE ARRIVAL OF A SECOND SHEET AT SAID HEATING MEANS FOR OPERATING SAID HEATING MEANS TO SUPPLY A SECOND AMOUNT OF HEAT, DIFFERING FROM SAID FIRST AMOUNT OF HEAT, TO SAID SECOND SHEET WITHIN SAID PREDETERMINED TIME INTERVAL.

2. Apparatus as defined in claim 1 wherein said heating means comprises a first and a second heater at said heating station spaced along said fixed path by a distance corresponding to the length of one step of movement of said carrier means whereby a sheet on said carrier means is located in operative relationship with said first heater at the conclusion of one step of movement of said carrier means and in operative relationship with said second heater at the conclusion of the next successive stop of movement of said carrier means, said heater control means controlling operation of said first heater, and second heater control means for operating said second heater to supply equal amounts of heat to first and second sheets advanced into operative relationship therewith.

3. Apparatus as defined in claim 1 wherein said forming station is spaced from said second heater by a distance corresponding to one step of movement of said carrier means and said second control means operates said second heater to maintain a substantially constant termperature in the region occupied by sheets in operative relationship with said second heater.