PRODUCTION OF A FIBER-REINFORCED THERMOPLASTIC PIPE

Abstract

In a method for producing a pipe made of a fiber-reinforced thermoplastic material, two workpieces of the material are provided. The workpieces are introduced into a tool having a core and two part molds surrounding the core. The workpieces are heated and shaped between the core and the part molds to give a structural part of the pipe. The core is removed from the structural parts, the structural parts being held on the part molds, and joining regions of the structural parts are oriented towards one another. The structural parts are joined to one another in the joining regions to form the pipe. The pipe is released from the part molds, wherein the part molds are moved away from one another after shaping in order to remove the core, and are then moved back together in order to orient the structural parts towards one another.

Claims

1. A method for producing a pipe made of a fiber-reinforced thermoplastic material, which comprises the steps of: providing at least two workpieces formed of the fiber-reinforced thermoplastic material; introducing all of the workpieces into a tool, the tool having at least one core and at least two part molds surrounding the core; heating the workpieces resulting in heated workpieces, each of the heated workpieces is shaped between the core and the part molds to form a structural part of the pipe; removing the core from structural parts by moving the part molds away from one another after shaping in order to remove the core, and are then moved back together in order to orient the structural parts towards one another, the structural parts being held on the part molds; orienting joining regions of the structural parts towards one another with an aid of the part molds; joining the structural parts to one another in the joining regions to form the pipe; and releasing the pipe from the part molds.

2. The method according to claim 1, which further comprises using the two part molds in a form of half-shells to shape, together with the core, the two workpieces into the two structural parts in a form of pipe halves.

3. The method according to claim 1, which further comprises joining the structural parts by welding and/or adhesive bonding in the joining regions to form the pipe.

4. The method according to claim 1, which further comprises holding at least one of the structural parts on the part molds with an aid of a negative pressure.

5. The method according to claim 1, which further comprises during a shaping step, forming flange parts on the structural parts, the flange parts have or form the joining regions or form part of the joining regions, and the structural parts are joined to form a flange by joining the flange parts.

6. The method according to claim 1, which further comprises machining the structural parts after shaping in order to provide and/or machine the joining regions before they are oriented towards one another.

7. The method according to claim 1, wherein the joining regions are each provided as an overlap region of the two structural parts that are to be joined.

8. The method according to claim 7, which further comprises pressing the structural parts, for joining in the joining regions, against one another with an aid of a pressure source.

9. The method according to claim 8, which further comprises using compressed air as at least part of the pressure source, wherein the compressed air serves to establish an increased pressure in an interior of the pipe that is to be joined, and a counter-pressure is provided by at least one of the part molds.

10. The method according to claim 1, which further comprises producing the pipe in a form of an air-conditioning pipe for a vehicle.

11. The method according to claim 1, which further comprises providing a laminar workpiece as at least one of the workpieces.

12. The method according to claim 12, wherein the workpieces have a thickness of 0.05 mm to 0.6 mm.

13. The method according to claim 1, which further comprises providing at least one of the workpieces as a laterally held film.

14. The method according to claim 1, which further comprises heating at least one of the workpieces outside the tool and/or during transport to the tool.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0039] FIG. 1 is a sequence scheme for the production of a pipe with a flange according to the invention; and

[0040] FIG. 2 is a sequence scheme for the production of a flangeless pipe.

DETAILED DESCRIPTION OF THE INVENTION

[0041] FIG. 1 illustrates a method for the production of a pipe 2 with a flange 4 from a fiber-reinforced thermoplastic material 6.

[0042] In step a) two workpieces 8a, 8b made of the material 6 are provided. The workpieces 8a,b are heated to above the softening point by means of a heating device 10, which here is indicated only by dashed lines. To that end, the heating device 10 forms a heating panel (infrared, IR). The workpieces 8a, 8b in the form of two semi-finished products are thus conveyed under the heating panel. Each of the workpieces 8a, 8b is a film and is held laterally or at its periphery by a holding device 12 that is depicted symbolically as a spring. The workpieces 8a, 8b are laminar with a thickness d of in this case 0.1 mm.

[0043] In step b) the workpieces 8a, 8b are conveyed into a tool 14 which is held in this case in a press 13 that is not illustrated in greater detail. The path between the heating device 10 (IR panel) and the tool 14 is heated. In the tool 14, the workpieces 8a, 8b are placed above and below a core 16 of the tool 14. The tool 14 is in three parts and is heated and contains as first part the core 16 and as second and third parts two part molds 18a, 18b. In FIG. 1, the core 16 is illustrated only schematically, and at different scales, in order to clarify the method.

[0044] In step c) the press 13 with the heated tool 14 is closed (indicated by arrows) and a negative pressure 27 in the form of a vacuum is applied between the semi-finished products or workpieces 8a, 8b and the cavities 20a, 20b of the part molds 18a, 18b. On closing, the workpieces 8a, 8b are shaped into structural parts 22a, 22b of the pipe 2in each case one between the core 16 and one of the part molds 18a, 18b. Flange parts 28a, 28b are in this case formed on the structural parts 22a, 22b. Thus, in the example, only two part molds 18a, 18b in the form of half-shells are provided in order to shape two workpieces 8a, 8b into two structural parts 22a, 22b in the form of pipe halves. The flange parts 28a, 28b then form joining regions 32a, 32b which are subsequently joined together in order to join the two structural parts 22a, 32b. In this context, the heated tool 14 means that the workpieces 8a, 8b are heated or retain their prior heating. The structural parts 22a, 22b are held on the respective part molds 18a, 18b in a conventional manner, not explained in greater detail here, by application of the negative pressure 27 in the form of a vacuum between the structural parts 22a, 22b and the cavities 20a, 20b. In order to generate the negative pressure 27, the part molds 18a, 18b contain suction or negative pressure ducts 24a, 24b which lead to a respective negative pressure port 26a, 26b.

[0045] In step d) the press 13 is opened and the core 16 is removed, as indicated by an arrow. The negative pressure 27 in the negative pressure ducts 24a, 24b remains, and the structural parts 22a, 22b remain suctioned or held in the part molds 18a, 18b.

[0046] In step e) the press 13 is closed again. The structural parts 22a, 22b remain held in the part molds 18a, 18b also during the closing procedure. In the process, the flange parts 28a, 28b or joining regions 32a, 32b are oriented towards one another. This takes place because the press 13 is opened and closed along the same path and the joining regions have already been created with the correct orientation when produced in step c). The flange parts 28a, 28b are pressed against one another with the aid of the press 13 or the tool 14 and are heated and thus welded by irradiation by a further heating device 10 (in dotted lines). Thus, the structural parts 22a, 22b are joined, in the joining region 32a, 32b, to form the pipe 2in this case by welding but alternatively or additionally by adhesive bonding. The structural parts 22a, 22b are joined by joining the flange parts 28a, 22b. The re-closing of the press 13 is again symbolized by two arrows. In this case, the flange parts 28a, 22b form a welding/adhesive bonding zone which is heated. Thus, the part molds 18a, 18b are moved away from one another after shaping in order to remove the core 16, and are then moved back together in order to orient the structural parts 22a, 22b towards one another, the structural parts 22a, 22b being held, or remaining, on the part molds 18a, 18b.

[0047] In step f) the press 13 is once again opened so that the now finished pipe 2 can be removed, which is indicated by an arrow. It is now also possible to remove the holding devices 12.

[0048] FIG. 2, which largely matches FIG. 1, shows the manufacture of a pipe 2 with no flange, wherein steps a), b) and c) match those of FIG. 1 and are carried out identically.

[0049] Step c1) shows a moment, following step c) from FIG. 1, when after shaping of the workpieces 8a, 8b to give the structural parts 22a, 22b these are already held on the part molds 18a, 18b by the negative pressure 27, but the tool 14 has already been slightly opened again, as indicated by movement arrows.

[0050] In another subsequent step c2) a trimming procedure takes place at the locations indicated by arrows 30. The trimming procedure involves separating the flange parts 28a, 28b from the rest of the structural parts 22a, 22b. This represents machining of the structural parts 22a, 22b which takes place after shaping of the latter and before they are once again oriented towards one another. The machining creates alternative joining regions 32a, 32b which are now located, as seen in the figure, at the lower rim of the structural part 22a and at the upper rim of the structural part 22b. Thus, the structural parts 22a, 22b are machined after shaping in order to provide the joining region 32a, 32b before they are oriented towards one another. Thus, in this case an overlap region 34a, 34b of the two structural parts 22a, 22b that are to be joined is created as the joining region 32a, 32b.

[0051] In step d), matching FIG. 1, the core 16 is removed from the tool 14 or press 13.

[0052] In step e), matching FIG. 1, the structural parts 22a, 22b are oriented with respect to the now alternative joining regions 32a, 32b, which in this case are overlap regions 34a,b of the structural parts 22a,b. By applying an increased pressure in the internal region 36 of the pipe 2 that is to be created, and a negative pressure or vacuum in the exterior 38, the joining regions 32b are respectively pressed outwards, that is to say towards the joining regions 32a of the structural part 22a, or towards the part molds 18a, 18b, in which situation the structural part 22a braces against the part molds 18a, 18b. Thus, increased pressure in the internal region 36 and negative pressure or vacuum in the external region 38 together form a pressure means 40 for pressing the overlap regions 34a, 34b or joining regions 32a, 32b against one another. Here, the direction of the pressure is indicated symbolically by arrows. Here too, the heating of the welding/adhesive bonding zone (joining region 32a, 32b), or the welding and/or adhesive bonding of the structural parts 22a, 22b to give the finished pipe 2, is brought about by means of a heating device 10 which once again is indicated only symbolically. The structural parts 22a, 22b, for joining in the joining region 32a, 32b, are pressed against one another with the aid of the pressure means 40. Here, compressed air is used as part of the pressure means 40, wherein the compressed air serves to establish an increased pressure in the internal region 36 of the pipe 2 that is to be joined, and a counter-pressure is also provided by at least one of the part molds 18a, 18b.

[0053] In step f) similarly to FIG. 1 above, the press 13 is opened and the pipe 2 is removed in the direction of the arrow.

[0054] The method serves to produce pipes 2 in the form of air-conditioning pipes for an aircraft as vehicle. The work pieces 8a, 8b may already be heated outside the tool 14 and during transport to the tool 14.

[0055] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0056] 2 Pipe [0057] 4 Flange [0058] 6 Material [0059] 8a,b Workpiece [0060] 10 Heating device [0061] 12 Holding device [0062] 13 Press [0063] 14 Tool [0064] 16 Core [0065] 18a,b Part mold [0066] 20a,b Cavity [0067] 22a,b Structural part [0068] 24a,b Negative pressure duct [0069] 26a,b Negative pressure port [0070] 27 Negative pressure [0071] 28a,b Flange part [0072] 30 Arrow [0073] 32a,b Joining region [0074] 34a,b Overlap region [0075] 36 Internal region [0076] 38 Exterior [0077] 40 Pressure means [0078] d Thickness