Solvay & Cie

Michel Lorge

Roger Houba

In the manufacture of oriented hollow articles made of thermoplastic material by the steps of extruding a continuous hot tubular parison of thermoplastic material; pre-blowing such parison in a pre-blowing mold to produce preforms having a cylindrical body with a diameter not more than 20% greater than that of the parison; thermally conditioning the resulting preforms at a temperature sufficient to cause orientation of the thermoplastic material when it is being stretched; and effecting a final blow-molding of the thermally conditioned preforms, the mechanical properties of the resulting articles in the vicinity of their base are improved by carrying out the pre-blowing step while holding each parison tightly between two half-molds defining a cavity which has the shape, at the location of the base of the preform, of a quarter sphere of diameter equal to that of the preform, and cutting off the resulting flash by means of an elongated blade having a semi-circular cross section and a diameter corresponding to that of the base of the cavity, and mounted at the base of one of the half-molds, the blade traveling against the base of the cavity in a direction perpendicular to the closure plane of the mold.

Device for manufacture of hollow articles

In the manufacture of oriented hollow articles made of thermoplastic material by the steps of extruding a continuous hot tubular parison of thermoplastic material; pre-blowing such parison in a pre-blowing mold to produce preforms having a cylindrical body with a diameter not more than 20% greater than that of the parison; thermally conditioning the resulting preforms at a temperature sufficient to cause orientation of the thermoplastic material when it is being stretched; and effecting a final blow-molding of the thermally conditioned preforms, the mechanical properties of the resulting articles in the vicinity of their base are improved by carrying out the pre-blowing step while holding each parison tightly between two half-molds defining a cavity which has the shape, at the location of the base of the preform, of a quarter sphere of diameter equal to that of the preform, and cutting off the resulting flash by means on an elongated blade having a semicircular cross section and a diameter corresponding to that of the base of the cavity, and mounted at the base of one of the half-molds, the blade traveling against the base of the cavity in a direction perpendicular to the closure plane of the mold.

Process for the manufacture of oriented hollow articles made of

The production of oriented hollow plastic articles having no weakened zone particularly in their bottom is ensured by blow molding of preforms having a base sealed along a straight line of length practically the same as half the perimeter of their cylindrical lateral part and gradually by changing from the cylindrical shape to the rectilinear shape in the region of the base so that the perimeter remains practically constant throughout all cross-sections.

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Brussels, Belgium

Michel Lorge