Apparatus for vacuum forming hollow plastic articles

Abstract

Abstract An apparatus for forming at least one planar sheet of heatfusible plastic into a hollow article by heating the plastic sheet to its fusion temperature; folding the heated sheet so as to bring preselected portions of the sheet together and holding other portions thereof spaced apart; and fusing the contacting portions together. An open frame supports and holds opposite edges of the heat-fusible plastic sheet during the heating of both planar surfaces of the sheet and the moving of the sheet parallel to a two section hinged planar mold. The edges of the sheet also may be preheated before its planar surfaces are heated. A vacuum is applied to draw the heated sheet into the mold cavities and concurrently the heated sheet is released form its supporting frame. The mold is then folded to fold the plastic sheet between the folded sections of the mold, which sections are then clamped in their folded positions. If desired, a sheet of insulation, such as of plastic foam, may be inserted between the folded portions of the sheet before the mold sections are folded together. Next these clamped sections are pressed to fuse together preselected portions of the folded sheet. These preselected portions may have been further heated before fusion and a cooling medium may be circulated through the mold sections to set the formed article. Compressed air then may be applied to one of the mold sections to release the article from that one section as the mold is opened. Lastly, air and/or a pusher is employed to eject the article from the other mold section.

Inventors

• 👤 Herbert J Earle

Bibliographic Details