Method for the production of hollow bodies from thermoplastic plastic

Abstract

The invention relates to a method for the production of hollow bodies from thermoplastic plastic. The method comprises the extrusion of at least two sheet-like preforms consisting of thermoplastic plastic, the introduction of the preforms into a preferably multipart molding die with a molding cavity which at least partially defines the contour of the hollow body to be manufactured, and the shaping of the preforms inside the die, using a vacuum and/or gas pressure in the first heat of the material. The method is distinguished in that at least two preforms to be shaped into a hollow body and to be connected are extruded successively, that is to say sequentially, in time and are shaped simultaneously.

What is claimed is: 
     
         1 - 12 . (canceled) 
     
     
         13 . A device for production of a hollow body, the device comprising:
 at least one extruder and at least one extrusion head with the die gap designed as a sheet die, the extrusion head having at least one melt duct arranged on a segment of an arc of a circle or on an arc of a circle and designed as an annular gap, characterized by means for spreading a melt stream in the form of an arc of a circle into a single sheet melt stream.   
     
     
         14 . A fuel container comprising:
 thermoplastic plastic which has been obtained by the extrusion blow molding of two sheet preforms of thermoplastic plastic, characterized in that the preforms are of two successive portions of a single melt extrusion which form two half shells of the fuel container: and   wherein the two half shells have a different mass distribution.   
     
     
         15 . The fuel container of  claim 14  wherein:
 the two successive portions of the single melt extrusion have a different mass distribution from one another. 
 
     
     
         16 . The fuel container of  claim 15  wherein:
 the two successive portions of the single melt extrusion have a different mass distribution further including a different wall thickness from one another. 
 
     
     
         17 . The fuel container of  claim 15  wherein:
 the two successive portions of the single melt extrusion have a different mass distribution further including a different weight from one another. 
 
     
     
         18 . The fuel container of  claim 14  wherein:
 the two successive portions each comprise multilayer coextrudate. 
 
     
     
         19 . A device for production of a hollow body, the device comprising:
 at least one extruder;   at least one extrusion head with a die having a die gap to form thermoplastic plastic into successive sheet preforms;   a first gripping device having gripping jaws to clamp a sheet preform of the successive sheet preforms and move the sheet preform away from the extrusion head at least transversely with respect to an extrusion direction of the extrusion head; and   wherein the gripping jaws are pivotable about a longitudinal axis defined by the extrusion direction.   
     
     
         20 . The device of  claim 19  wherein:
 the first gripping device is arranged to move the sheet preform away from the extrusion head to a second gripping device and transfer the sheet preform to the second gripping device. 
 
     
     
         21 . The device of  claim 20  wherein:
 the second gripping device comprises a first pair of gripping jaws and a second pair of gripping jaws. 
 
     
     
         22 . The device of  claim 21  wherein:
 the first pair of gripping jaws and the second pair of gripping jaws are at a distance from one another and the distance is variable. 
 
     
     
         23 . The device of  claim 21  wherein:
 the first gripping device is arranged to transfer the sheet preform to either of the first pair of gripping jaws or the second pair of gripping jaws. 
 
     
     
         24 . The device of  claim 23  wherein:
 the first pair of gripping jaws of the second gripping device are arranged to receive a first sheet preform of the successive sheet preforms from the first gripping device; and 
 the second pair of gripping jaws of the second gripping device are arranged to receive a second sheet preform of the successive sheet preforms from the gripping device. 
 
     
     
         25 . The device of  claim 24  wherein:
 the second gripping device is arranged to provide the first sheet preform and the second sheet preform into a molding die to form the first sheet preform and the second sheet preform into the hollow body. 
 
     
     
         26 . The device of  claim 25  wherein:
 the second gripping device is arranged above the molding die. 
 
     
     
         27 . The device of  claim 19  wherein:
 the gripping jaws are pivotable 180° about the longitudinal axis defined by the extrusion direction. 
 
     
     
         28 . The device of  claim 19  wherein:
 the die gap is adjustable.