METHOD FOR CONNECTING METAL FITTINGS TO PIPES MADE OF FIBER-REINFORCED COMPOSITE MATERIAL, AND LINES OBTAINED WITH THIS METHOD

Abstract

A system comprising a pipe and at least one fitting, wherein the pipe is made essentially of a thermoplastic, fiber-reinforced composite material, and the fitting is made essentially of titanium or a titanium alloy, and the pipe and the fitting are connected in a fluid-tight manner

Claims

1. A system comprising: a pipe and at least one fitting, wherein the pipe is made essentially of a thermoplastic, fiber-reinforced composite material, and wherein the fitting is made essentially of titanium or a titanium alloy, and wherein the pipe and the fitting are connected in a fluid-tight manner

2. The system according to claim 1, wherein the pipe is plastically deformable at an elevated temperature.

3. The system according to claim 1, wherein the thermoplastic, fiber-reinforced composite material comprises, as a matrix, essentially polymers on the basis of polyetherketones.

4. The system according to claim 1, wherein the polymers are selected from the group consisting of PEEK and PEKK.

5. The system according to claim 1, wherein the pipe is resistant to hydraulic fluids.

6. The system according to claim 1, wherein the pipe is resistant to low-density phosphate ester-based hydraulic fluids.

7. The system according to claim 1, wherein the thermoplastic, fiber-reinforced composite material comprises, as reinforcing fibers, essentially carbon fibers.

8. The system according to claim 1, wherein the fitting has a recess configured to receive the pipe.

9. The system according to claim 1, wherein a weld seam connects the fitting and the pipe in a fluid-tight manner

10. The system according to claim 1, wherein the system is located in an aircraft or spacecraft.

11. A method for producing a system according to claim 1, comprising the steps of: a) positioning the pipe, the fitting with respect one another such that a part region of the fitting comes to rest against the outside of the pipe, b) positioning a support for the pipe wall inside the pipe, c) welding the pipe and the fitting to one another, wherein the welding is performed using an ultrasonic welding apparatus.

12. The method according to claim 11, further comprising a step of positioning a sleeve on the fitting such that a part region of the sleeve comes to rest against the outside of the pipe rather than a part region of the fitting coming to rest against the outside of the pipe.

13. The method according to claim 11, wherein the pipe wall support is part of the fitting.

14. The method according to claim 11, wherein the ultrasonic welding apparatus has a rotating sonotrode which is moved around the parts to be welded.

15. The method according to claim 11, wherein the ultrasonic welding apparatus has a sonotrode around which the parts to be welded are rotated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIGS. 1 to 4 illustrate various combinations of fittings with pipes made of composite material.

[0012] In the figures, identical reference signs are used for identical or at least similar elements, components or aspects. It is noted that the embodiments described in detail below are merely illustrative and non-limiting.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] FIG. 1 shows, in a longitudinal sectional illustration, a fitting (1) made of metal which can be pushed over a pipe made of CFRP (2). The fitting has a region (4) having an internal diameter that is such that the CFRP pipe (2) can be pushed into the fitting (1). Preferably, this internal diameter corresponds to the external diameter of the pipe. One end (5) of the pipe (2) can abut against a region (3) of the fitting (1) having a smaller internal diameter than the region (3) of the fitting. Preferably, the internal diameter of the region (3) can correspond to the internal diameter of the pipe (2). In order to weld the pipe (2) and the fitting (1), the sonotrode of an ultrasonic welding unit is guided circumferentially along the surface of the region (3) of the fitting (1) such that the material of the pipe (2) in the fitting (1) partially melts and, after solidification, forms a fluid-tight connection between the pipe (2) and the fitting (1). In that context, a retainer (6) can be inserted into the fitting (1) and the pipe (2). It is thus possible to prevent certain deformations of the pipe (2). The retainer (6) can be removed after the welding procedure.

[0014] FIG. 2 shows, in a longitudinal sectional illustration, a fitting (1) made of metal and a pipe made of CFRP (2), which are arranged in abutment. An essentially tubular sleeve (7) made of metal can be pushed over the pipe (2) and the fitting (1) such that a first region (8) of the sleeve (7) overlaps the pipe (2) circumferentially and a second region (9) of the sleeve (7) overlaps the fitting (1) circumferentially. In order to weld the pipe (2) to the sleeve (7), the sonotrode of an ultrasonic welding unit is guided circumferentially along the surface of the first region (8) of the sleeve (7) such that the material of the pipe (2) inside the sleeve (7) partially melts and, after solidification, forms a fluid-tight connection between the pipe (2) and the sleeve (7). In that context, the welding unit is operated in a first operating state that permits hybrid welding (CFRP/metal). In order to weld the fitting (1) to the sleeve (7), the sonotrode of an ultrasonic welding unit is guided circumferentially along the surface of the second region (9) of the sleeve (7) such that the material of the fitting (1) inside the sleeve (7) partially melts and, after solidification, forms a fluid-tight connection between the fitting (1) and the sleeve (7). In that context, the welding unit is operated in a second operating state that permits the welding of metals. In that context, a retainer as described in FIG. 1 can be inserted into the fitting (1) and the pipe (2), and is removed again after welding.

[0015] FIG. 3 shows, in a longitudinal sectional illustration, a fitting (10) made of metal and a pipe made of CFRP (2), which are arranged in abutment. In that context, the fitting (10) has a first region (13) and a second region (14), the external sides of which are conical and form essentially the same angle with respect to the internal side (12). The pipe (2) can be pushed over the first conical region (13) of the fitting (10) until the pipe (2) abuts against the front edge (15) of the region (14) of the fitting (10). In the process, the region (16) of the pipe (2) widens conically. A conical sleeve (11) made of metal can be pushed over the pipe (2) and the fitting (10) such that a first region (8) of the sleeve (7) overlaps the pipe (2) circumferentially and a second region (9) of the sleeve (7) overlaps the fitting (10) circumferentially. Welding of the pipe (2) and the fitting (10) to the sleeve (11) can be carried out as illustrated in FIG. 2, it being unnecessary to use a retainer.

[0016] FIG. 4 shows, in a longitudinal sectional illustration, a fitting (20) made of metal and a pipe made of CFRP (2). In that context, the fitting (20) has a first region (21) and a second region (22), wherein the second region has a slot into which the pipe (2) can be pushed. The distal region (23) of the fitting (20) can be conical, both on the internal side and on the external side. Welding of the pipe (2) to the fitting (20) can be carried out as per the description relating to FIG. 1. A retainer is not required.

[0017] While the invention has been illustrated and described in detail in the drawings and the above description, it is intended that such illustrations and descriptions are merely illustrative or exemplary and non-limiting, and therefore the invention is not restricted by the disclosed embodiments. In the claims, the word having does not exclude other elements and, and the word one or the indefinite article a does not exclude a greater number.

[0018] The mere event that certain features are specified in different dependent claims does not restrict the subject matter of the invention. In addition, combinations of these features can advantageously be used.

[0019] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.