FR2944574A1 - Method for assembling plastic conduit sections of air supply conduit of turbo compressor, involves installing screwed collar clamp around female end of conduit section in order to guarantee sealing at level of junction of sections - Google Patents

Abstract

The method involves passing a hot plastic parison obtained at an end of an extrusion phase through a metal ring (5) fixed at a mold. A male end (1-1) of a conduit section (1) is introduced into a female end (2-1) of another conduit section (2) manufactured by extrusion blowing such that peripheral positioning beads (3, 4) of the sections are engaged with each other, and the metal ring is sandwiched between the sections. A screwed collar clamp (6) is installed around the female end at a right side of the metal ring in order to guarantee sealing at level of junction of the sections.

Description

The subject of the present invention is a method for assembling two sections of plastic duct manufactured by extrusion blow molding, in particular of two sections of a duct supplying air to the turbocharger of a supercharged internal combustion engine. .

According to the invention, one of the duct sections to be assembled or first duct section has a male end while the other pipe section or second duct section has a female end. These two duct sections are conventionally equipped with peripheral positioning beads engaging one into the other after assembly. The positioning bead of the first con duct section is more precisely located in the immediate vicinity of the male end of this section while the positioning bead of the second section of duct is located a little behind the female end of that one. -this.

As a result, after assembly, the two pipe sections are nested one inside the other over a part of their length. Blow extrusion is a process for converting thermoplastic materials into hollow bodies well known to those skilled in the art.

According to this method, in a first phase or extrusion phase, a tube of molten plastic material is peeled off, and in a second phase or blowing phase, this parison is introduced into a tube. closed mold and it is blown air to press against the cooled walls of the mold and thus give it the desired shape. The solidified part is then demolded and the excess plastic cut to obtain the final object. The extrusion blow molding technique is widely used for the manufacture of duct sections for supplying air to the turbocharger of supercharged internal combustion engines. Such conduits are subjected to very high temperature and pressure constraints; it is therefore necessary to take adequate measures to prevent creep of the plastic material and ensure sealing at the junction area of two pipe sections, and exclude any loosening of the female section. For this purpose, after the extrusion molding of the con duct sections, is now installed inside the male end of the first section a metal ring acting as a limiting device.

2 pressure, then after assembly of the two sections, we equip the female end of the second section, to the right of the metal ring, a screw clamp to ensure sealing at the junction of the two sections.

Such a method is however not likely to give complete satisfaction insofar as to allow the establishment of the metal ring, it is necessary to machine the inside of the male end of the first section of conduit a groove device with very precise dimensions, then insert this ring force into the housing thus created using a special tool. However, this need is likely to increase to a large extent the time required for the manufacture of pipe sections and their cost and the pollution of parts. The object of the present invention is to propose a method of assembling two sections of plastic duct manufactured by extrusion blow molding, namely a first section of duct having a male end and a second section of duct having a female end of a type to remedy these disadvantages. According to the invention, the first step of this method consists of passing, during the blowing phase of the first duct section, the parison made of hot plastic material obtained at the end of the extrusion phase through at least one metal ring attached to the mold. This metal ring is overmolded on the ex-dull face of the first pipe section around its male end and close to its peripheral positioning bead. After assembly of the two pipe sections, such a metal ring acts as a compression limiter and prevents any phenomenon of creep of the plastic material under the effect of the temperature and pressure stresses to which it is exposed so as to guarantee a good sealing between the two sections of pipe. The overmoulding of the metal ring around the first duct section during the blowing phase of this section constitutes the essential characteristic of the process according to the invention. This feature is particularly advantageous insofar as it makes it possible to avoid having to dig a housing for receiving the metal ring around the male end of the first duct section, after manufacture of this section, by extrusion-molding then to insert this ring in this housing using a special tool.

The second step of the process according to the invention consists in forcing, after demolding, the male end of the first pipe section into the female end of the second duct section previously manufactured by extrusion blow molding.

After assembly, the peripheral positioning beads of the two pipe sections engage one into the other, and the metal ring is sandwiched between these two sections. The last step of the process according to the invention consists in putting in place a screw clamp around the female end of the second pipe section, in line with the metal ring so as to guarantee the sealing at the level of the junction of the two sections of conduit. According to a first variant of the invention, during the blowing phase, a single metal ring is overmolded on the outer face of the first pipe section, around its male end. According to this first variant of the invention, the seal between the two pipe sections is formed at their peripheral positioning beads which are compressed against one another by the screw clamp. According to a second variant of the invention, during the blowing phase, two metal rings, preferably identical, are overmolded on the outer face of the first duct section, around its male end. According to this second variant of the invention, the two metal rings are not fixed in the blow mold in close proximity to one another but at a distance so that, during the blowing phase, an annular plastic bulge is formed therebetween. The tightness between the two pipe sections is then achieved at this annular bulge following the compression of the plastic material constituting these two sections at this level by the screw clamp collar. According to a third variant of the invention, before step 35 of assembly of the two pipe sections, a plastic ring is overmolded by injection on the metal ring molded on the outer face of the first pipe section so that this metal ring is embedded in the plastic material.

This third variant of the invention comprises an additional injection step, generally performed in the blow mold, but requiring the addition in this mold of an auxiliary injection unit.

To avoid any sealing defect, the injected plastic ring must be perfectly welded to the first conduit, so that the metal ring is embedded in it. It is indeed this plastic ring which makes it possible to seal between the two pipe sections after assembly. According to this third variant of the invention, it is of course essential that the plastic material constituting the plastic ring injected posteriorly is compatible with the plastic material constituting the two pipe sections.

The characteristics of the process which is the subject of the invention will be described in more detail with reference to the appended non-limiting drawings in which: FIG. 1 is a diagram showing the junction zone of two duct sections assembled by the method according to in the first variant of the invention, FIG. 2 is a half section of the joining zone of two duct sections assembled by the method according to the second variant of the invention, FIG. 3 is a half section of the zone. joining two sections of duct assembled by the method according to the third variant of the invention. According to FIG. 1, the method according to the invention allows the assembly of a first section of duct 1 having a male end 11 and of a second section of duct 2 having a female end 21.

The two pipe sections 1, 2 comprise a peripheral bead 3, 4 of oval section engaging one into the other in the assembled position. The peripheral positioning bead 3 of the first section 1 is located in the immediate vicinity of its male end 11 while the peripheral positioning bead 4 of the second section 2 is located a little behind its female end 21 so that after assembly both sections 1, 2 overlap for a fraction of their length. According to FIG. 1, a metal ring 5 acting as a compression limiter is overmolded on the external face of the first pipe section 1 at the level of the peripheral positioning bead 3.

After assembly, the metal ring 5 is sandwiched between the first duct section 1 and the second duct section 2 in the overlap zone of these sections. A screw clamp 6 is furthermore positioned around the outer face of the second pipe section 2 at the circumferential positioning bead 4. In the overlap area, the second pipe section 2 is thus sandwiched between the metal ring 5 and the screw clamp 6. This clamp 6 thus makes it possible to seal 15 between the two pipe sections 1, 2 following the crushing of the peripheral positioning beads. 3, 4. According to FIG. 2, two metal rings 51, 52, separated by an annular space 10, are overmolded on the outer face of the first duct section 1 at the circumferential positioning bead 3. A bulge of plastic material 7 is formed in the space 10 separating the two metal rings 51, 52 during the blowing step. After assembly, the metal rings 51, 52 are again sandwiched between the first duct section 1 and the second duct section 2 in the overlap zone of these sections. A screw clamp 6 is positioned around the outer face of the second pipe section 2 near its female end 21 at the plastic bulge 7.

In the overlap zone, the second con duct section 2 is thus sandwiched between the metal ring 5 and the screw clamp 6. This screw clamp 6 thus makes it possible to seal between the two sections of duct 1, 2 following the collapse 35 of the bulge 7. According to FIG. 3, a single metal ring 5 'is also overmolded on the external face of the first section of duct 1, around 6 its male end 11 and near its peripheral positioning bead 3. A plastic ring 8 is further overmolded by injection on the metal ring 5 'so that the latter ring 5' is embedded in the plastic material. After assembly and positioning of a screw clamp 6, the overmolding of this complementary ring 8 makes it possible to create sealing zones 9 between the two pipe sections 1, 2. NOMENCLATURE 1 11 2 21 3, 4 5 , 5 ', 51, 52 6 7 8 9 First pipe section Male end Second pipe section Female end Peripheral beads Metal rings Screw clamp Plastic expansion Plastic bushing Sealing zones15

Claims (3)

CLAIMS 1 °) A method of assembling two sections of plastic duct manufactured by extrusion blow molding, in particular of two sections of a duct supplying air to the turbocharger of a supercharged internal combustion engine, the one of these pipe sections or first pipe section (1) having one male end (11) while the other pipe section or second pipe section (2) has a female end (21), and these pipe sections (1, 2) being equipped with peripheral positioning beads (3, 4) engaging one into the other after assembly, characterized by the following steps: during the blowing phase of the first pipe section (1), the parison made of hot plastic material obtained at the end of the extrusion phase is passed through at least one metal ring (5) attached to the mold, acting as a compression limiter, so as to overmould this ring (5) on the outer face of this first section of duct (1), around its male end (11) and near its peripheral positioning bead (3), after demolding, the male end (11) of the first duct section (1) in the female end (21) of the second duct section (2) previously manufactured by blow extrusion so that the peripheral positioning beads (3, 4) of these two duct sections (1, 2) come into engagement, and that the metal ring (5) is sandwiched between these two sections (1, 2), and a screw clamp (6) is put in place around the female end (21) of the second pipe (2), to the right of the metal ring (5), so as to ensure sealing at the junction of the two pipe sections (1, 2). 2) Method according to claim 1, characterized in that during the blowing phase, two metal rings (5, 52) are overmolded on the outer face of the first duct section (1), around its male end (II). ). 3) Method according to claim 1, characterized in that 9 before the assembly step of the two pipe sections (1, 2), is on-mold by injection a plastic ring (8) on the ring metal (5 ') overmolded on the outer face of the first pipe section (1) so that the metal ring (5') is embedded in the plastic material.