Process for manufacturing a hollow body and the manufactured body

Abstract

A process for manufacturing a diesel tank or filler pipe by an extrusion-blow molding machine configured to manufacture a gasoline tank or filler pipe. The extrusion-blow molding machine includes a coextrusion head including at least one extruder configured to provide during a first period of time a first material that is a barrier to liquids and/or gases, such that during the first period of time the coextrusion head produces a first multilayer parison from which the gasoline tank or filler pipe can be manufactured. The extruder is further configured to provide during a second period of time a second material distinct from the first material, such that during the second period of time the coextrusion head produces a second multilayer parison from which the diesel tank or filler pipe can be manufactured.

Claims

1. A process for manufacturing a gasoline tank or a filler pipe for a gasoline tank, a diesel tank and/or a filler pipe for a diesel tank comprising providing a extrusion-blow molding machine comprising a coextrusion head comprising at least one extruder and configured to manufacture at different time periods, a first multilayer parison comprising a barrier layer and a second multilayer parison that does not comprise a barrier layer, and said extruder being connected to a feeding line which is connected to a hopper, said hopper being connected by a first inlet to a source of a first material for pushing said first material towards said extruder to form said barrier layer of said first multilayer parison and by a second inlet to a source for a second material for pushing said second material towards said extruder to form said non-barrier layer of said second multilayer parison, wherein said first inlet and said second inlet are controlled such that said first material and said second material enter the hopper one at a time; during a first period of time extruding the first multilayer parison comprising the first material with the extrusion-blow molding machine, and blow-molding the first multilayer parison to form a gasoline tank or a filler pipe for a gasoline tank; during a second period of time stop pushing said first material towards the extruder by closing the first inlet, and start pushing said second material towards the extruder by opening the second inlet; during a third period of time extruding the second multilayer parison comprising the second material with the extrusion-blow molding machine, and blow-molding the second multilayer parison to form a diesel tank or a filler pipe for a diesel tank; wherein the first material is a fuel-impermeable resin, and wherein the second material is high density polyethylene or a mixture of high density polyethylene and adhesive.

2. The process according to claim 1, wherein the first material is EVOH copolymer.

3. The process according to claim 1, wherein after said second period the extruder is purged to remove from the extruder the second material.

4. The process according to claim 1, wherein the coextrusion head comprises at least one additional extruder configured to provide adhesive.

5. The process according to claim 4, wherein during the second period of time and when the second material is high density polyethylene (HDPE), the additional extruder is configured to provide high density polyethylene (HDPE).

6. The process according to claim 4, wherein during the second period of time and when the second material is a mixture of high density polyethylene (HDPE) and adhesive, the additional extruder is configured to provide an amount of adhesive that is lower than the amount of adhesive provided during the first period of time.

7. The process according to claim 1, wherein after said first period the extruder is purged to remove from the extruder the first material.

8. The process according to claim 1, wherein the first period of time gasoline tanks are produced.

9. The process according to claim 1, wherein the first period of time filler pipes for gasoline tanks are produced.

10. The process according to claim 4, wherein the second period of time diesel tanks are produced.

11. The process according to claim 4, wherein the second period of time filler pipes for diesel tanks are produced.

12. The process according to claim 4, wherein the first period of time and the second period of time are repeated in alternating order.

13. The process according to claim 12, wherein during each repeated first period of time the same product is produced.

14. The process according to claim 13, wherein during each repeated first period of time gasoline tanks are produced.

15. The process according to claim 12, wherein during each repeated second period of time the same product is produced.

16. The process according to claim 15, wherein during each repeated second period of time diesel tanks are produced.

17. The process according to claim 12, wherein during each repeated first period of time different products are produced.

18. The process according to claim 12, wherein during each repeated second period of time a different products are produced.

19. The process according to claim 12, wherein between each repeated period of time the extruder is purged.

20. The process according to claim 12, wherein during each repeated first period of time gasoline tanks are produced and during each repeated second period of time diesel tanks are produced.

21. The process according to claim 20, wherein between each repeated period of time the extruder is purged.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is illustrated, in a non limitative way, by the accompanying FIGS. 1 to 4.

(2) FIGS. 1 and 2 illustrate schematically a particular embodiment of a coextrusion head of an extrusion-blow moulding machine to which the present invention may be applied;

(3) FIG. 3 illustrates a manufacturing sequence of gasoline and diesel tanks, in accordance with a first particular embodiment of the invention; and

(4) FIG. 4 illustrates a manufacturing sequence of gasoline and diesel tanks, in accordance with a second particular embodiment of the invention.

DESCRIPTION OF THE INVENTION

(5) For clarity reason, the invention is described hereafter only for the particular case of the production of diesel tanks and gasoline tanks for motor vehicles. It is to note that the invention can be applied in the same manner to the case of the production of diesel filler pipes and gasoline filler pipes for motor vehicles.

(6) The same reference numerals are used to indicate the same elements (or functionally-similar elements) throughout the separate FIGS. 1 to 4.

(7) FIG. 1 is a cross sectional view of a coextrusion head 1 according to a particular embodiment of the present invention. The coextrusion head 1 is a part of an extrusion-blow moulding machine (not shown). The coextrusion head 1 is in charge of producing a multilayer parison 2.

(8) In this particular embodiment, the coextrusion head 1 comprises six extruders 11, 12, 13, 14, 15 and 16. In another embodiment, the coextrusion head can comprise more than or less than six extruders. Each extruder is in charge of extruding a layer of material.

(9) FIG. 2 is a 3D view of the top of the coextrusion head 1. In the example illustrated in FIG. 2, the coextrusion head 1 comprises six material feeding lines 21, 22, 23, 24, 25 and 26. Each feeding line is connected to one extruder of the coextrusion head 1. Each feeding line is in charge of distributing/pushing a material towards the extruder to which it is connected. In this example, the feeding line 21 is connected to the extruder 11, the feeding line 22 is connected to the extruder 12, the feeding line 23 is connected to the extruder 13, the feeding line 24 is connected to the extruder 14, the feeding line 25 is connected to the extruder 15, and the feeding line 26 is connected to the extruder 16.

(10) According to a particular embodiment of the present invention, one side of the feeding line 23 can be connected to the extruder 13 and the other side of the feeding line 23 can be connected to the outlet port of a hopper (not shown). According to an advantageous embodiment, this hopper can comprise two inlet ports. For example, EVOH can entered in the hopper via the first inlet port and a mixture of HDPE and adhesive can entered in the hopper via the second inlet port. Opening and closing of the inlet ports can be advantageously controlled such that EVOH and the mixture of HDPE and adhesive enter one at a time in the hopper.

(11) FIG. 3 illustrates a manufacturing sequence Si of gasoline and diesel tanks, in accordance with a first particular embodiment of the invention.

(12) During a period of time T1, the extrusion-blow moulding machine is, for example, configured to manufacture one or several gasoline tanks. In this example, during the period of time T1 the coextrusion head 1 is configured to produce a multilayer parison comprising six layers of material. More precisely, during the period of time T1 the coextrusion head 1 is configured such that: the extruder 11 extrudes (for example) HDPE; the extruder 12 extrudes (for example) adhesive; the extruder 13 extrudes (for example) EVOH; the extruder 14 extrudes (for example) adhesive; the extruder 15 extrudes (for example) recycled plastic; and the extruder 16 extrudes (for example) HDPE (with or without additive).

(13) During this period of time T1, the multilayer parison produced by the coextrusion head 1 is blow-moulded in a mould (not shown) to form the wall of a gasoline tank. In this example, the wall of the gasoline tank is composed of six layers of material arranged in the following order: an inner layer comprising HDPE, a layer comprising adhesive, a layer comprising EVOH, a layer comprising adhesive, a layer comprising recycled plastic and an outer layer comprising HDPE.

(14) Before the start of a period of time T3 during which the extrusion-blow moulding machine is, for example, configured to manufacture one or several diesel tanks, the coextrusion head 1 is purged during a period of time T2. In this example, the extruder 13 is purged with a mixture of HDPE and adhesive. In other words, the mixture of HDPE and adhesive is introduced in the extruder 13 so as to push out the EVOH remaining in the extruder 13. The duration of the period of time T2 is such that it allows the complete evacuation of the EVOH out of the extruder 13.

(15) Once the step of purging is completed, the manufacture of diesel tanks can start. As mentioned above, during the period of time T3 the extrusion-blow moulding machine is, for example, configured to manufacture one or several diesel tanks. In this example, during the period of time T3 the coextrusion head 1 is configured to produce a multilayer parison comprising six layers of material. More precisely, during the period of time T3 the coextrusion head 1 is configured such that: the extruder 11 extrudes (for example) HDPE; the extruder 12 extrudes (for example) adhesive; the extruder 13 extrudes (for example) a mixture of HDPE and adhesive. Advantageously, this mixture is the same as the one used during the step of purging (i.e. period of time T2); the extruder 14 extrudes (for example) adhesive; the extruder 15 extrudes (for example) recycled plastic; and the extruder 16 extrudes (for example) HDPE (with or without additive).

(16) Advantageously, the amount of adhesive extruded by the extruder 12 and/or the extruder 14 during this period of time T3 can be lower than the amount of adhesive extruded by this extruder 12 and/or this extruder 14 during the period of time T1.

(17) During this period of time T3, the multilayer parison produced by the coextrusion head 1 is blow-moulded in a mould (not shown) to form the wall of a diesel tank. In this example, the wall of the diesel tank is composed of six layers of material arranged in the following order: an inner layer comprising HDPE, a layer comprising reduced adhesive, a layer comprising a mixture of HDPE and adhesive, a layer comprising reduced adhesive, a layer comprising recycled plastic and an outer layer comprising HDPE.

(18) Before switching from the manufacture of diesel tanks to the manufacture of gasoline tanks, the coextrusion head 1 is once again purged during a period of time T4. In this example, the extruder 13 is purged with EVOH. In other words, EVOH is introduced in the extruder 13 so as to push out the mixture of HDPE and adhesive remaining in the extruder 13. The duration of the period of time T4 is such that it allows the complete evacuation of the mixture of HDPE and adhesive out of the extruder 13.

(19) Then, during a period of time T5, the extrusion-blow moulding machine is, for example, once again configured to manufacture one or several gasoline tanks. During this period of time T5, the coextrusion head 1 operates in the same way as described above with reference to the period of time T1.

(20) The duration of the periods of time T1, T2, T3, T4 and T5 can be different. For example, the duration of the period of time T1 can be such that it allows the manufacture of 1000 gasoline tanks, the duration of the period of time T3 can be such that it allows the manufacture of 500 diesel tanks and the duration of the period of time T5 can be such that it allows the manufacture of 3000 gasoline tanks. For example, the duration of the period of time T2 can be around 2 hours and the duration of the period of time T4 can be more than 2 hours.

(21) FIG. 4 illustrates a manufacturing sequence S2 of gasoline and diesel tanks, in accordance with a second particular embodiment of the invention.

(22) During a period of time T6, the extrusion-blow moulding machine is, for example, configured to manufacture one or several gasoline tanks. In this example, during the period of time T6 the coextrusion head 1 is configured to produce a multilayer parison comprising six layers of material. More precisely, during the period of time T6 the coextrusion head 1 is configured such that: the extruder 11 extrudes (for example) HDPE; the extruder 12 extrudes (for example) adhesive; the extruder 13 extrudes (for example) EVOH; the extruder 14 extrudes (for example) adhesive; the extruder 15 extrudes (for example) recycled plastic; and the extruder 16 extrudes (for example) HDPE (with or without additive).

(23) During this period of time T6, the multilayer parison produced by the coextrusion head 1 is blow-moulded in a mould (not shown) to form the wall of a gasoline tank.

(24) As illustrated in the example of FIG. 4, the coextrusion head 1 is purged during a period of time T7. In this example, the extruders 12, 13 and 14 are purged with HDPE.

(25) During a period of time T8 the coextrusion head 1 is configured such that: the extruder 11 extrudes (for example) HDPE; the extruder 12 extrudes (for example) HDPE; the extruder 13 extrudes (for example) HDPE; the extruder 14 extrudes (for example) HDPE; the extruder 15 extrudes (for example) recycled plastic; and the extruder 16 extrudes (for example) HDPE (with or without additive).

(26) Advantageously, during this period of time T8 pure thermoplastic diesel tank (i.e. free of adhesive and free of EVOH) can be manufactured.