Method for manufacturing a hollow body, in particular a fuel tank

Patent metadata

Field	Value
Publication number	US-2016346987-A1
Application number	US-201615157844-A
Country	US
Kind code	A1
Filing date	May 18, 2016
Priority date	May 27, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

A method for manufacturing a hollow body, typically a tank, from a plastic material. The method includes molding a preform into shells in a molding tool; joining an insert to an inner surface of a shell of said shells, the insert defining a sub volume within the hollow body to be made; joining together the shells to form the hollow body by closing the molding tool and applying a main pressure to a main volume enclosed by the shells. It is proposed to apply a sub pressure to the sub volume while applying the main pressure to the main volume, such that a pressure difference between the main volume and the sub volume is bigger than 0.20 bar (P 1′− P 2′ >0.20 bar) and smaller than 3.00 bar (P 1′− P 2′< 3.00 bar).

First claim

1 . A method for manufacturing a hollow body from a plastic material, said method comprising the steps of:
molding a preform into shells in a molding tool; joining an insert to an inner surface of a shell of said shells, said insert defining a sub volume within the hollow body to be made; joining together the shells to form the hollow body by closing the molding tool and applying a main pressure to a main volume enclosed by the shells, wherein there is applied a sub pressure to the sub volume while applying the main pressure to the main volume, such that a pressure difference between the main volume and the sub volume is bigger than 0.20 bar and smaller than 3.00 bar.

2 . The method of claim 1 , wherein the pressure difference between the main volume and the sub volume is smaller than 2.00 bar.

3 . The method of claim 1 , wherein the pressure difference between the main volume and the sub volume is bigger than 0.5 bar.

4 . The method of claim 1 , wherein the joining of an insert to the inner surface of the shell comprises:
arranging the insert in the shell against the inner surface and closing the molding tool with a core inserted between the shells; and applying a first pressure to a main volume enclosed by the shells and the core, while applying a second pressure to the sub volume.

5 . The method of claim 4 , wherein a pressure difference between the first pressure and the second pressure is bigger than 0.20 bar and smaller than 3.00 bar.

6 . The method of claim 1 , wherein the molding tool comprises two cavities and a core, and wherein the step of molding a preform into shells comprises:
introduction of a preform in the form of a parison into the cavities; introduction of a core inside the parison, said core having first been fitted with the insert; closure of the molding tool so that the cavities come into leaktight contact with the core; pressing of the parison against the cavities by blowing through the core and/or applying a vacuum behind the cavities.

7 . The method of claim 6 , wherein the joining of an insert to the inner surface of the shell comprises installing the insert on an inner wall of the parison using a device attached to the core; the method further comprising:
opening the mold to withdraw the core before the step of joining the shells.

8 . The method of claim 1 , wherein applying the main pressure and the sub pressure is performed using a main line and a sub line distinct from the main line, respectively.

9 . The method of claim 8 , wherein the main line is provided with a main valve and the sub line is provided with a sub-valve, and the method further comprises controlling the main valve and the sub valve for synchronizing the applying of pressure to the main volume and the sub volume.

10 . The method of claim 1 , wherein applying the main pressure and the sub pressure is performed using a main line and a sub line connected to the main line, respectively, wherein there is provided a pressure reducing means in the sub line.

11 . The method of claim 1 , wherein applying the main pressure and/or the sub pressure is performed through an inflation needle, with which a wall of the shells is pierced.

12 . The method of claim 1 , wherein the main pressure is higher than 4 bar, preferably higher than 7 bar.

13 . The method of claim 1 , wherein the step of molding a preform into shells in a molding tool is performed at a pressure which is lower than the main pressure.

14 . The method of claim 1 , wherein the insert is a ventilation assembly.

15 . A hollow body manufactured according to the method of claim 1 , wherein the hollow body is preferably a fuel tank.

Assignees

• Plastic Omnium Advanced Innovation & Res

Inventors

• Guezennec Yvonnig
• TOUTAIN Stephane
• Coing Jean-Francois
• Dupont Serge

Classifications

• B29C49/60

  Blow-needles · CPC title

• B29C49/0411

  Means for defining the wall or layer thickness · CPC title

• B29C49/20

  of articles having inserts or reinforcements {; Handling of inserts or reinforcements} · CPC title

• B29C49/22 Primary

  using multilayered preforms or parisons · CPC title

• B29C49/783

  blowing pressure · CPC title