Mold, molding machine and method for molding by extrusion blow molding
A mold for manufacture by extrusion blow molding includes two parts. At least one of the parts includes at least one first section having a first molding surface including at least one primary contact region to form, by pressing, zones for fixing at least one internal component inside a parison, a second section having a second molding surface, the second section of the part of the mold being movable with respect to the associated at least one first section of the part of the mold, and at least one third section movable with respect to the associated at least one first section of the part of the mold, the at least one third section having a third molding surface including at least one secondary contact region to reduce, by pressing, a predetermined volume inside the parison.
1 . A mold for manufacturing by extrusion blow-molding a hollow tank body made of plastic material for a motor vehicle from a parison, the tank comprising at least one internal component fixed to an interior of the parison during the molding of the hollow body, the mold comprising two parts movable relative to one another delimiting internally, when they are closed against each other, a total molding surface intended to reproduce a predetermined shape of the hollow body to be manufactured, at least one of the parts of the mold comprises:
at least one first section having a first molding surface of a first portion of the hollow body to be manufactured, said first molding surface comprises at least one primary contact region configured to form, by pressing, a fixing region for fixing said at least one internal component inside the parison,
a second section having a second surface for molding a second portion of the hollow body to be manufactured, said second section of the part of the mold is movable relative to the associated at least one first section of the part of the mold at least between an intermediate closed position and a final closed position of the parts of the mold, and
at least one third section having a third molding surface of a third portion of the hollow body to be manufactured, said third molding surface comprises at least one secondary contact region, said at least one third section of the part of the mold is movable relative to the associated at least one first section of the part of the mold at least between an intermediate position and a final position wherein the at least one secondary contact region is configured to reduce, by pressing, a predetermined volume within the parison.
2 . The mold according to claim 1 , wherein the first molding surface of the part of the mold is configured to extend along a circumscribed surface containing the primary contact regions associated with the part of the mold.
3 . The mold according to claim 2 , wherein the circumscribed surface of the first molding surface of the part of the mold comprises a predetermined margin distance at least around the primary contact regions of said at least one internal component associated with the part of the mold in order to limit ripples of material around each fixing region.
4 . The mold according to claim 3 , wherein the predetermined margin distance at least around the fixing regions is between 1 mm and 60 mm.
5 . The mold according to claim 2 , wherein the circumscribed surface of the first molding surface of at least one of the parts of the mold is at least equal to 15% of the total molding surface.
6 . The mold according to claim 1 , wherein the secondary contact region or at least one of the secondary contact regions is configured so as, when the third section of the part of the mold is in its final position, to bring two opposing regions of the parison into contact so as to locally weld them together.
7 . The mold according to claim 1 , wherein the third molding surface of the part of the mold comprises several secondary contact regions.
8 . The mold according to claim 7 , wherein the at least one third section of the part of the mold is divided into several subsections separated from each other, and each secondary contact region is carried by a subsection of the at least one third section of the part of the mold.
9 . The mold according to claim 8 , wherein the subsections of the at least one third section of the part of the mold are movable relative to one another between an intermediate position and the final position.
10 . The mold according to claim 1 , wherein each part of the mold comprises at least one first section, a second section, and at least one third section.
11 . The mold according to claim 10 , wherein the at least one first mold section of each part of the mold comprises at least one primary contact region configured to press the parison against said same at least one internal component in order to form at least two different fixing regions of said same at least one internal component for fixing said same at least one internal component inside the parison during the molding of the hollow body.
12 . The mold according to claim 1 , wherein only one of the parts of the mold comprises at least one first section, a second section, and at least one third section.
13 . The mold according to claim 1 , wherein, in the final closing position, the at least one first mold section of each part of the mold is surrounded by its associated second section of the part of the mold.
14 . The mold according to claim 1 , wherein, in the final closed position, the at least one third mold section of each part of the mold is surrounded by its associated at least one first section of the part of the mold.
15 . The mold according to claim 1 , wherein the at least one first and/or third section of the part of the mold comprises multiple first and/or third sections.
16 . A molding machine for molding by extrusion blow-molding a hollow tank body made of plastic material for a motor vehicle from a parison, the machine comprising the mold according to claim 1 .
17 . A molding method for molding by extrusion blow-molding a hollow tank body made of plastic for a motor vehicle from a parison, the tank comprising at least one internal component fixed inside the parison during the molding of the hollow body, the method comprising the following steps:
a) introducing said at least one internal component and the parison in a molten state into an open mold in two parts so that said at least one internal component is surrounded by the parison, at least one part of the mold comprising at least one first section, a second section and at least one third section internally delimiting a first molding surface, a second molding surface, and a third molding surface, respectively, of a total molding surface of the mold,
b) moving the at least one first section of the part of the mold to bring the mold into an intermediate closed position wherein the at least one first section of the part of the mold presses the parison against said at least one internal component in order to fix said at least one internal component inside the parison, the first molding surface being configured to form, by pressing, multiple fixing regions for fixing said at least one internal component inside the parison,
c) moving the second section of the part of the mold relative to the at least one first section of the part of the mold to bring the mold into a final closing position wherein the two parts of the mold are closed against each other and internally delimit the total molding surface intended to reproduce a predetermined shape of the hollow body to be manufactured,
d) moving the at least one third section of the part of the mold relative to the at least one first section of the part of the mold to bring the at least one third section into a position wherein the third molding surface presses the parison in order to reduce a predetermined volume within the parison,
e) performing a blowing of the parison by pressing said parison on the total molding surface of the mold using a pressurized gas,
f) opening the mold to take out the manufactured hollow body.
18 . The molding method according to claim 17 , wherein a pressurized gas is introduced inside the parison to pre-blow said parison between step a) and step b).