Method and device for producing a tube from thermoplastic synthetic material via injection moulding

Abstract

The invention relates to a method for producing a tubular component as an article from a thermoplastic synthetic material while using an injection-molding device having a tool that forms an article cavity, having means for filling the article cavity with a thermoplastic molding compound, and having an injection device for injecting a fluid into the article cavity, wherein the injection device comprises a nozzle body, wherein the method provides that the nozzle body is used as a mold core for molding the shape of an end of the article, that the nozzle body is used as a carrier for an additional component to be incorporated into the article, wherein: a) the nozzle body first equipped with the additional component, b) the nozzle body is introduced into the closed article cavity, or the tool is closed around the nozzle body, c) the article cavity in a further method step is at least partially filled with the thermoplastic molding compound, d) a pressurized fluid is then induced into the article cavity by means of the injection device, wherein part of the molding compound is displaced into a secondary cavity, and e) the article is de-molded. The invention furthermore relates to an injection-molding device for carrying out the method.

Claims

1. A method of producing a tubular component as an article from thermoplastic material via an injection-molding device having a tool that comprises an article cavity to form the article, the method comprising: a) equipping a nozzle body of an injection device of the injection-molding device with an additional component to be incorporated into the article, wherein the nozzle body provides a carrier for the additional component; b) introducing the nozzle body to the article cavity, wherein the nozzle body provides a mold core which shapes at least a portion of the article; c) filling the article cavity at least partially with the thermoplastic material, wherein the thermoplastic material is provided from the injection-molding device; d) introducing a pressurized fluid into the article cavity such that a portion of the thermoplastic material is displaced from the article cavity, wherein the pressurized fluid is provided from the injection device of the injection-molding device; and e) de-molding the article.

2. The method as claimed in claim 1, wherein the nozzle body is configured as a projectile carrier to receive at least one projectile, wherein the nozzle body, prior to method step b), is equipped with the at least one projectile, and wherein the pressurized fluid introduced into the article cavity drives the at least one projectile through the article cavity while displacing a molten core of the thermoplastic material from the article cavity.

3. The method as claimed in claim 1, wherein the additional component is embedded into the thermoplastic material.

4. The method as claimed in claim 1, wherein the nozzle body, after method step d) and prior to method step e), is removed from the article cavity while the additional component remains in the article.

5. The method as claimed in claim 1, wherein the additional component comprises a permanently magnetic ring which is releasably fitted onto the nozzle body.

6. The method as claimed in claim 1, wherein the article comprises a duct for a liquid container.

7. The method as claimed in claim 1, wherein an internal wall of the article in a longitudinal direction is profiled such that the article is provided with one or more longitudinal ribs.

8. The method as claimed in claim 1, wherein the internal wall of the article is configured with at least one constriction.

9. An injection-molding device for producing a tubular component as an article from a thermoplastic synthetic material, having a tool that forms an article cavity, having means for filling the article cavity with a thermoplastic molding compound, having at least one injection device for injecting a fluid into the article cavity, wherein the injection device comprises a nozzle body which has at least one fluid duct which is capable of being supplied with a pressurized fluid, wherein the nozzle body is configured as a mold core for molding the shape of an end of the article, wherein the nozzle body is a carrier for an additional component to be incorporated into the article.

10. The injection-molding device as claimed in claim 9, wherein the nozzle body is configured as a projectile carrier for receiving a projectile as a displacement member for the molding compound.

11. The injection-molding device as claimed in claim 10, wherein the nozzle body has a shape-imparting shank which conjointly with the article cavity forms a molding cavity that is capable of being filled with the molding compound.

12. The injection-molding device as claimed in claim 11, wherein the shank is profiled.

13. The injection-molding device as claimed in claim 11, wherein the shank has a first comparatively large and a second comparatively small cross section, and in that the shank tapers off in the direction toward the distal end.

14. The injection-molding device as claimed in claim 13, wherein the distal end is configured as a projectile receptacle, and in that the projectile has a cross section that is larger than the second cross section.

15. The method as claimed in claim 6, wherein the duct comprises a filling duct for the liquid container.

16. The method as claimed in claim 1, wherein the article comprises a filler tube for a liquid container of a motor vehicle.

17. The method as claimed in claim 16, wherein the filler tube comprises a filling duct and a ventilation line.

18. The method as claimed in claim 1, wherein the mold core of the nozzle body shapes at least an end of the article.

19. The method as claimed in claim 1, wherein the nozzle body is introduced into the article cavity when the tool is closed or by closing the tool around the nozzle body.

20. The method as claimed in claim 1, wherein the thermoplastic material is displaced from the article cavity into a secondary cavity or another volume.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained hereunder by means of an exemplary embodiment that is illustrated in the drawings in which:

(2) FIG. 1 shows a schematic partial section through an injection-molding device according to the invention; and

(3) FIG. 2 shows a partial section through a filler tube for a urea container of a motor vehicle, said filler tube having been produced by the method according to the invention while using the tool according to the invention.

DETAILED DESCRIPTION

(4) The injection-molding device 1 according to the invention comprises a tool 2 (only illustrated in outlines) which is composed of two mold halves, for example, which define an article cavity 3. The article cavity 3 can be configured as the negative of the filler tube 4 that is illustrated in FIG. 2, for example. The tool 2 can comprise a plurality of movable components in the form of slides or the like, and at least one secondary cavity. The secondary cavity is capable of being blocked in relation to the article cavity 3 by means of slides. These details are not illustrated in the figure for reasons of simplification. An extruder and one or a plurality of sprue ducts which open into the article cavity 3 are likewise not illustrated.

(5) FIG. 1 shows an end of the article cavity 3 in a region which is configured for molding the shape of the filler head 5 of the filler tube 4 illustrated in FIG. 2.

(6) The injection-molding device 1 furthermore comprises an injection device 6 which comprises a nozzle body 7. The injection device 6 is likewise not completely illustrated in FIG. 1.

(7) The nozzle body 7 is movable relative to the tool 2 from a first, shape-imparting position to a second, de-molded position, wherein FIG. 1 shows the first, shape-imparting position. The nozzle body 7 in this shape-imparting position plunges into the article cavity 3 and seals the article cavity 3 at the end side. The article cavity 3 at the end that is distant from the injection device 6 communicates with the secondary cavity (not illustrated).

(8) The nozzle body 7 according to the invention is configured as a mold core and as a projectile carrier for receiving a projectile 8 from a thermoplastic synthetic material. The nozzle body 7 comprises a shank 9 which has a proximal end and a distal end, wherein the proximal end seals the article cavity 3 and the distal end receives the projectile 8.

(9) The shank 9 at the proximal end thereof has a first, comparatively large diameter; the shank 9 at the distal end thereof has a second, comparatively small diameter. The shank 9 in the region of the first diameter is provided with grooves 10 that extend in the longitudinal direction, said grooves 10 defining corresponding ribs in an internal delimitation wall of the article to be produced.

(10) The shank 9 conjointly with the article cavity 3 forms an annular space which by way of a sprue (not illustrated in the drawing) is capable of being filled with a thermoplastic molding compound.

(11) The sprue is not illustrated in the drawing, said sprue in relation to the advancing direction of the projectile 8 being located downstream.

(12) The article cavity 3 in the case of the exemplary embodiment illustrated in FIG. 1 comprises a branch in which the shape of a secondary tube 12 of the filler tube 4 can be molded. A second projectile 13 is disposed laterally on the nozzle body 7 in order for shape of the secondary tube 12 to be molded.

(13) The nozzle body 7 is penetrated by a fluid duct 15 through which a highly-pressurized fluid can be induced into the article cavity 3. The fluid duct 15 branches off toward the distal end of the shank 9, on the one hand, said fluid duct 15 opening in the direction toward the projectile 8, and on the other hand branches off toward the side in the direction toward the second projectile 13. The fluid, for example water, in a pressurized manner is driven by way of the fluid duct 15 toward the projectile 8 and toward the second projectile 13, wherein the projectile 8 and the second projectile 13, driven by the pressure of the fluid, displace the plastic molding compound that is located in the article cavity 3 into the secondary cavity.

(14) The projectile 8 that is plug-fitted onto the distal end of the shaft 9 has a maximum external diameter which is larger than the second diameter of the shank, such that the projectile 8 forms a temporary undercut of the nozzle body 7, said temporary undercut being capable of being filled with the molding compound.

(15) Furthermore, an additional component in the form of an annular magnet 14 is plug-fitted onto the shank 9 of the nozzle body 7 in the region of the first diameter, said annular magnet 14 conjointly with the nozzle body 7 being moved into the article cavity 3 prior to the latter being filled with the thermoplastic molding compound.

(16) In the case of the method according to the invention, for example, the tool 2 is first closed, thereafter the nozzle body 7 conjointly with the annular magnet 14 that is releasably plug-fitted onto the shank 9 is moved from a second de-molding position to a first, shape-imparting position in which the shank 9 plunges into the article cavity 3 and seals the latter. Thereafter the article cavity 3 is filled with the thermoplastic molding compound by way of one or a plurality of sprues (not illustrated). Full or partial filling can be performed. The thermoplastic molding compound also fills the article cavity in the region of the molding cavity 17 that is formed between the nozzle body 7 and the tool 2, wherein the thermoplastic molding compound encloses and embeds the annular magnet 14. The thermoplastic molding compound furthermore flows behind the projectile 8 since the diameter of the shank 9 (second diameter) directly upstream of the projectile 8 is smaller than the maximum diameter of the projectile 8.

(17) Once the article cavity 3 has been filled with the thermoplastic molding compound the secondary cavity (not shown) is released, for example by way of hydraulically activatable slides.

(18) In a further method step thereafter, a pressurized fluid, for example water, is driven through the fluid duct 15 toward the projectile 8 and toward the second projectile 13. The fluid drives the projectiles 8, 13 through the article cavity 3, wherein the projectile 8 molds the shape of a primary tube 16 and the second projectile 13 molds the shape of the secondary tube 12. The projectiles 8, 13 displace a molten core of the molding compound, the remaining wall/delimitation wall of the tube configured as the filler tube 4 left standing.

(19) In a further method step the nozzle body 7 is moved to a second, de-molded, that is to say retracted position, wherein the annular magnet 14 remains in the molding compound that has been filled.

(20) The article is subsequently de-molded. The article in the form of the filler tube 4 is illustrated in FIG. 2. The filler tube comprises the primary tube indicated by the reference sign 16, which defines a charging duct in a container, and the secondary tube indicated by the reference sign 12, which forms a ventilation line. The filler tube 4 comprises the filler head 5 having an orifice connector 18 which is provided with an external thread 19. The orifice connector 18 encloses a filling duct 20 which extends from the orifice connector 18 through the filler head 5 into the primary tube 16.

LIST OF REFERENCE SIGNS

(21) 1 Injection-molding device 2 Tool 3 Article cavity 4 Filler tube 5 Filler head 6 Injection device 7 Nozzle body 8 Projectile 9 Shank 10 Grooves 12 Secondary tube 13 Second projectile 14 Annular magnet 15 Fluid duct 16 Primary tube 17 Molding cavity 18 Orifice connector 19 External thread 20 Filling duct