Multi-layer hollow body, method for manufacturing such a hollow body, and comprssion-blow-moulding mould

Abstract

Hollow body formed of several elements of multi-layer plastic welded together, comprising a barrier layer that is a barrier to liquids and to gases and which elements are extended towards the outside by an appendage comprising the barrier layers. Method for manufacturing such a hollow body by compression moulding in a multi-part mould comprising welding curbs and delimiting, when the mould is being closed, a shallow slot near these curves into which slot at least the barrier layers of the elements of the hollow body are forced to flow. Multi-part compression-blow-moulding mould comprising welding curbs which, when the mould is closed, leave between them a space with a height of cross section that decreases towards the outside and which is extended by a shallow and broad slot intended to compress the plastic.

1 . A hollow body made of plastic of multi-layer polymeric structure, comprising at least one internal barrier layer which is impermeable to gases and to liquids, in which body at least two elements of similar structure are welded together and wherein the welded elements are extended towards the outside of the hollow body by an appendage comprising the barrier layers.  
     
     
         2 . Hollow body according to  claim 1 , wherein, in addition to the barrier layers, the appendage also comprises at least one polymeric layer of a nature similar to that of one of the other layers present in each element, on any side of a barrier layer.  
     
     
         3 . Hollow body according to  claim 1 , wherein the appendage is folded down against the exterior surface of the hollow body.  
     
     
         4 . Hollow body according to  claim 3 , wherein the appendage is secured to the exterior surface.  
     
     
         5 . Hollow body according to  claim 1 , which is a tank intended to contain a liquid and/or gaseous fuel.  
     
     
         6 . A method for manufacturing, using the compression-moulding technique, a hollow body made of plastic of multi-layer polymeric structure comprising a barrier layer that is a barrier to liquids and to gases, by welding at least two elements together, wherein: 
 a) the elements are inserted in an open multi-part mould,    b) at least part of the ends of the elements which are to be assembled are gripped between the welding kerbs arranged at the periphery of at least two mould parts, so as to superpose them,    c) the mould parts are pressed together so as to weld the elements together by closing the mould, and, at the same time,    d) at least the barrier layers of the structure of these elements are forced to flow into a shallow and broad slot delimited by a space separating two mould parts near the welding kerbs and the cross section of which narrows at the end nearest the outside of the mould cavity,    e) the mould parts are continued to be pressed together so as to form an appendage which emerges from the surface of the hollow body on the outside of the mould cavity,    f) the mould is opened,    g) the hollow body thus produced is extracted from the mould.    
     
     
         7 . Method according to  claim 6 , wherein the elements are also shaped inside the mould by injecting a blowing fluid into the mould so as to press the elements against the walls of the mould.  
     
     
         8 . Method according to  claim 6 , wherein after opening the mould at the end of the assembly operation, the appendage is also folded down against the surface of the hollow body, to which it is then secured.  
     
     
         9 . Method according to  claim 6 , for producing a fuel tank made of plastic of multi-layer polymeric structure.  
     
     
         10 . A compression-blow-moulding mould formed of at least two distinct parts comprising, at their periphery, welding kerbs capable of gripping and welding distinct elements made of plastic of multi-layer polymeric structure, wherein the welding kerbs of two mould parts facing one another leave between then, when the mould is closed, a space the height of the cross section of which decreases towards the outside of the mould cavity and is extended by a shallow and broad slot intended to greatly compress the plastic while the mould is being closed.