INJECTION MOLDING DEVICE FOR MANUFACTURING TUBES HAVING AN UNDERCUT INTERNAL GEOMETRY, PREFERABLY AN INTERNAL THREAD, AND METHOD FOR MANUFACTURING TUBES OF SAID TYPE

Abstract

The invention relates to an injection molding device for manufacturing tubes having an internal thread, having a tool that forms an article cavity, having means for filling the article cavity with a thermoplastic molding compound, having an injection device for injecting a fluid toward a projectile to be driven through the article cavity, wherein the injection device comprises a projectile carrier having at least one injection nozzle and having at least one projectile receptacle for a projectile as a displacement member for the molding compound, wherein the projectile carrier at an end that is remote from the projectile receptacle is provided with a thread-bearing stamping core which is adjustable relative to the projectile carrier between a thread-forming first position and a demolded second position, wherein the stamping core in the thread-forming position plunges into the article cavity and seals the latter.

Claims

1-13. (canceled)

14. An injection molding device for manufacturing tubes having an internal thread, having a tool that forms an article cavity, having means for filling the article cavity with a thermoplastic molding compound, having an injection device for injecting a fluid toward a projectile to be driven through the article cavity, wherein the injection device comprises a projectile carrier having at least one injection nozzle and having at least one projectile receptacle for a projectile as a displacement member for the molding compound, wherein the projectile carrier at an end that is remote from the projectile receptacle is provided with a thread-bearing stamping core which is adjustable relative to the projectile carrier between a first position that forms a thread, and a demolded second position, wherein the stamping core in the first position plunges into the article cavity and seals the latter, wherein the stamping core is configured as a rotary core.

15. The injection molding device as claimed in claim 14, wherein the projectile carrier is configured as a multiple-part first mold core having a smooth-walled shank and having a receptacle for the stamping core.

16. The injection molding device as claimed in claim 14, wherein the smooth-walled shank of the projectile carrier has an external diameter which approximately corresponds to the internal diameter of the tube to be molded as the article.

17. The injection molding device as claimed in claim 14, wherein the receptacle for the stamping core is configured as a guide spindle for the stamping core, the former having a spindle drive that is complementary thereto.

18. The injection molding device as claimed in claim 14, comprising at least one second mold core which in a first position plunges into the article cavity and bears on the smooth-walled shank of the projectile carrier so as to by way of the smooth-walled shank of the projectile carrier form a branch of the tube to be molded as the article.

19. The injection molding device as claimed in claim 14, wherein a second mold core in a first position plunges into the article cavity and engages in a depression in the smooth-walled shank of the projectile carrier so as to by way of the projectile carrier form a branch of the tube to be molded as the article.

20. A method for manufacturing tubes having an internal thread, by injection molding a thermoplastic molding compound by means of an injection molding device having a tool having an article cavity which substantially defines the external contour of a tube to be manufactured as the article, while using an injection device which is configured to drive a projectile through the article cavity that is filled with a thermoplastic molding compound while displacing a liquid core of the molding compound, and while using a projectile carrier which as a mold core is provided with a part that forms a thread, wherein the method comprises the following method steps: a) equipping the projectile carrier with a projectile; b) closing the tool around the projectile carrier, or introducing the projectile carrier into the closed tool such that the projectile carrier seals the article cavity; c) at least partially filling the article cavity with a plasticized molding compound, wherein an internal thread portion is formed in part of the article cavity; d) directing a pressurized fluid into the article cavity by means of the injection device such that the fluid drives the projectile through the article cavity while displacing part of the molding compound in such a manner that the projectile forms a tubular article that is configured as a hollow body; e) demolding the part of the projectile carrier that forms the contour the thread; and f) opening the tool and retrieving the article, wherein a stamping core which is removed by way of a rotating movement is used as the thread-forming part of the projectile carrier, and in that the stamping core in step e) is adjusted relative to the projectile carrier between a thread-forming first position and a demolded second position.

21. The method as claimed in claim 20, wherein the internal thread portion is widened in the manner of a sleeve.

22. The method as claimed in claim 20, wherein the tubular article is manufactured while using a second mold core having a tubular branch, wherein the second mold core in a first deployed position is brought to bear on a smooth-walled shank of the projectile carrier or engages in a depression in the smooth-walled shank of the projectile carrier.

23. The method as claimed in claim 22, wherein the second mold core after method step b) and before method step c) is moved to the first deployed position and is retracted before method step f).

24. The method as claimed in claim 20, wherein a filling tube of a fluid container for a motor vehicle, having a portion which is widened in the manner of a sleeve and provided with an internal thread, is manufactured as the tubular article.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0042] The invention will be explained hereunder with reference to the exemplary embodiment illustrated in the drawing in which:

[0043] FIG. 1 is a schematic partial view of an injection molding device.

DETAILED DESCRIPTION

[0044] For reasons of simplicity, one or a plurality of devices for extruding the thermoplastic molding compound are not illustrated. The injection molding device 1 comprises a tool which is composed of, for example, two mold halves which define an article cavity 3. The article cavity 3 can be configured, for example, as the negative of a tube (3D tube) that is curved multiple times in space. The tool 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 locked in relation to the article cavity 3 by means of slides. These details for reasons of simplicity are likewise not illustrated in the FIGURE.

[0045] The FIGURE shows an end of the article cavity 3 in the region of an end of the tube that is to be molded as the article, for example. The tool 2 comprises a sprue 4 which opens into the article cavity 3. An injection device 6 having a projectile carrier 7 is furthermore disposed on the tool 2. The projectile carrier 7 is configured as a multiple-part mold core. Said mold core comprises a projectile receptacle 8 which forms the leading end of the projectile carrier 7, a smooth-walled shank 9 that adjoins the projectile receptacle 8, and a receptacle 10 for a stamping core 11 which is configured as a rotary core. The stamping core 11 has a thread-forming, or thread-stamping, respectively, external contour. Said external contour can have one or a plurality of continuous or interrupted thread webs which produce an internal thread of the article to be fabricated, or of the tube to be fabricated, respectively, as will yet be explained later.

[0046] The projectile carrier 7 furthermore comprises a fluid duct 12 which extends from a base of the projectile carrier 7 to the projectile receptacle 8. A pressurized fluid, for example water, is capable of being driven by way of the fluid duct 12 through the projectile carrier 7 toward a projectile 13 that is plug fitted to the projectile receptacle 8. The projectile 13 is driven through the article cavity 3 by means of the pressure of the fluid that is supplied by way of the injection device 6. The projectile receptacle 8 is configured as a diameter step on the leading end of the projectile carrier 7. The projectile 13 has an internal diameter which corresponds to the diameter of the diameter step. The projectile 13 terminates so as to be flush with the external diameter of the smooth-walled shank 9. The external diameter of the smooth-walled shank 9 corresponds to the internal diameter of the tube to be fabricated. The annular space 14 that is formed between the smooth-walled shank 9 and the tool 2 is capable of being filled with the thermoplastic molding compound, as will yet be described hereunder, such that the tubular article in this region forms a calibrated tube end having an internal diameter that is predefined by the diameter of the smooth-walled shank 9.

[0047] A second mold core which is mounted in the tool 2 so as to be adjustable transversely relative to the longitudinal axis of the projectile carrier 7 is identified by the reference sign 15. In the position of the second mold core 15 shown in the FIGURE, said second mold core 15 bears tightly on the smooth-walled shank 9 of the projectile carrier 7. The tool 2 in this region is configured such that a port-type outlet, or a port-type branch, respectively, of the article to be molded can be configured by means of the second mold core 15. The end face of the second mold core 15 has a design embodiment that is complementary to the shell area of the smooth-walled shank 9.

[0048] In the method according to the invention, first the tool is closed around the projectile carrier 7 that is equipped with the projectile 13, for example. The second mold core 15 is brought to bear on the smooth-walled shank 9 of the projectile carrier 7.

[0049] As is illustrated also in the FIGURE, the mold core 11 is located in a thread-forming first position in which the stamping core 11 seals the article cavity 3. The stamping core 11 according to the exemplary embodiment has a diameter that is larger than the diameter of the smooth-walled shank 9. The article cavity 3 in the region in which the stamping core 11 projects into the article cavity 3 is likewise configured so as to have an enlarged diameter such that an end portion of the tube having a cross section that is widened in the manner of a sleeve is created in the region.

[0050] The article cavity 3 is then partially or completely filled by way of the sprue 4 with a molding compound of a thermoplastic plastics material. A tubular article having an internal thread portion is already created at this point of time in the region of the annular space 14.

[0051] After the article cavity 3 has been filled a pressurized fluid is injected through the projectile carrier 7. This fluid drives the projectile 13 through the article cavity 3. The projectile 13 herein displaces the molten core of the plasticized thermoplastic plastics material that has been filled into the article cavity 3.

[0052] The largest diameter of the projectile 13 corresponds to the external diameter of the smooth-walled shank 9 such that the projectile 13 generates a stationary tube wall, the wall thickness of the latter corresponding to the wall thickness of the tube wall in the region of the annular space 14.

[0053] The stamping core 11 has an encircling sealing shoulder 16 by way of which said stamping core 11 seals the article cavity 3, or the annular space 14, respectively. The sealing shoulder generates a smooth-walled sealing face of the article or tube, respectively, to be fabricated.

[0054] Once the projectile 13 has been driven through the article cavity 3, the second mold core 15 is moved to a retracted position; the stamping core 11 is thereafter moved from the thread-forming first position shown in the FIGURE to a second position in which said stamping core 11 releases the article cavity 3 or the annular space 14, respectively. This position is not shown in the FIGURE.

[0055] The article thereafter can be retrieved from the tool 2.

LIST OF REFERENCE SIGNS

[0056] 1 Injection molding device [0057] 2 Tool [0058] 3 Article cavity [0059] 4 Sprue [0060] 5 Not allocated [0061] 6 Injection device [0062] 7 Projectile carrier [0063] 8 Projectile receptacle [0064] 9 Smooth-walled shank [0065] 10 Receptacle for the stamping core [0066] 11 Stamping core [0067] 12 Fluid duct [0068] 13 Projectile [0069] 14 Annular space [0070] 15 Second mold core [0071] 16 Sealing shoulder