METHOD FOR PRODUCING A POLAR-CAP REINFORCEMENT AND A PRESSURE VESSEL, AND PRESSURE VESSEL HAVING POLAR-CAP REINFORCEMENT

Abstract

A method for producing a polar cap reinforcement of a pressure vessel includes providing a winding device including two winding plates, which are spaced apart and form a gap, in which there is a winding core; producing a resin-impregnated fiber laminate inside the gap generated by repeated winding around the winding core; detaching the fiber laminate from the winding device and applying the fiber laminate onto a first molding tool with the domed outer contour of a polar cap region of the inner vessel; positioning a second molding tool with the outer contour of the polar cap reinforcement to be produced, to enclose the fiber laminate between the first molding tool and the second molding tool; forming the shape of the polar cap reinforcement between the two molding tools by deforming the fiber laminate between the two molding tools; curing the fiber laminate to form the polar cap reinforcement.

Claims

1. A method for producing a polar cap reinforcement (30P) of a pressure vessel (10) comprising an inner vessel (20) and an outer layer of reinforcing fibers, which is wound around the inner vessel (20), wherein the inner vessel (20) has a cylindrical central region (21) and two domed polar cap regions (22;23) which seal the openings of the cylindrical central region (21), characterized by the following steps: a) providing a winding device (50) comprising two winding plates (51;52), which are spaced apart from one another and form a gap (55) between them, in which there is a winding core (54); b) producing a resin-impregnated fiber laminate (30) inside the gap (55), which is generated by repeated winding around the winding core (54) in the circumferential direction; c) detaching the fiber laminate (30) from the winding device (50) and applying the fiber laminate (30) onto a first molding tool (70) which has the domed outer contour of a polar cap region (22;23) of the inner vessel (20); d) positioning a second molding tool (71), which has the outer contour of the polar cap reinforcement (30P) to be produced, in order to enclose the fiber laminate (30) between the first molding tool (70) and the second molding tool (71); e) forming the shape of the polar cap reinforcement (30P) between the two molding tools (70;71) by deforming the fiber laminate (30) between the two molding tools (70;71) under pressure; f) curing the fiber laminate (30) to form the polar cap reinforcement (30P).

2. The method as claimed in claim 1, characterized in that the first molding tool (70) is the domed polar cap region (22;23) of the inner vessel (20), for which the polar cap reinforcement (30P) is to be produced, and the second molding tool (71) is removed after the curing of the fiber laminate (30) to form the polar cap reinforcement (30P).

3. The method as claimed in claim 1, characterized in that the cured polar cap reinforcement (30P) is released from the molding tools (70;71) and applied onto the domed polar cap region (22;23) of the inner vessel (20).

4. The method as claimed in one or more of claims 1 to 3, characterized in that the distance between the inner faces of the winding plates (51;52) of the winding device (50) is constant or decreases toward the winding core (54).

5. The method as claimed in one or more of claims 1 to 4, characterized in that, before the fiber laminate (30) is produced, the inner sides of the winding plates (50;51) are each coated with a detachable film (60;61) which is subsequently detached from the winding device (50) together with the fiber laminate (30).

6. The method as claimed in claim 5, characterized in that the fiber laminate (30) is deformed and cured together with the films (60;61) between the molding tools (70;71).

7. The method as claimed in one or more of claims 1 to 6, characterized in that method step c) involves initially separating a first winding plate (52) and the winding core (54) in order to place the fiber laminate (30) with the second winding plate (51) on the first molding tool (70), and then also removing the second winding plate (51).

8. A method for producing a pressure vessel (10) having at least one polar cap reinforcement (30P), characterized by the following steps: i. providing an inner vessel (20), which has a cylindrical central region (21) and two domed polar cap regions (22;23), which seal the openings of the cylindrical central region (21); ii. producing at least one polar cap reinforcement (30P) by a method as claimed in one of claims 1 to 7 and applying the polar cap reinforcement (30P) on a domed polar cap region (22;23) of the inner vessel (20); iii. producing a circumferential winding (30Z) on the cylindrical central region (21) of the inner vessel (20); iv. winding an outer winding (40) around the circumferential winding (30Z) and the at least one polar cap reinforcement (30P).

9. The method as claimed in claim 8, characterized in that the at least one domed polar cap region (22;23) of the inner vessel (20) has a connecting flange (14;15) which surrounds the annular polar cap reinforcement (30P) after the removal of the winding core (54).

10. A pressure vessel (10) comprising an inner vessel (20) and an outer layer of reinforcing fibers, which is wound around the inner vessel (20), wherein the inner vessel (20) has a cylindrical central region (21) and two domed polar cap regions (22;23) which seal the openings of the cylindrical central region (21), characterized in that the outer layer of reinforcing fibers has, in at least one domed polar cap region (22;23) of the inner vessel (20), a polar cap reinforcement (30P) having circumferential windings, which has been produced by a method as claimed in one of claims 8 and 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the drawings:

[0039] FIG. 1 shows a pressure vessel;

[0040] FIG. 2 shows a schematic longitudinal section through a pressure vessel according to FIG. 1;

[0041] FIG. 3 shows an enlarged view of a polar cap region with radial reinforcement;

[0042] FIG. 4 shows a schematic representation of a first embodiment of a winding device for producing a polar cap reinforcement;

[0043] FIG. 5 shows a winding device according to FIG. 4 with a fiber laminate that has been produced;

[0044] FIG. 6 shows the exemplary application of a fiber laminate on a first molding tool;

[0045] FIG. 7 shows the introduction of the fiber laminate between the first molding tool and a further second molding tool;

[0046] FIG. 8 shows the deformation of the fiber laminate under pressure between two molding tools; and

[0047] FIG. 9 shows a) a schematic representation of a second embodiment of a winding device and b) a polar cap reinforcement with a varying wall thickness on the polar cap region of an inner vessel.

DETAILED DESCRIPTION

[0048] A pressure vessel, or composite pressure vessel, to be produced with the polar cap reinforcement according to an embodiment is represented by way of example in FIG. 1. The pressure vessel 10 comprises a cylindrical central part 11 and two domed polar caps 12 and 13, which seal the openings of the cylindrical central part 11. Protruding connecting flanges 14 and 15 may be provided on these polar caps 12, 13, although the shape and arrangement of these connections 14, 15 are to be understood only schematically and by way of example. Such connecting flanges are also referred to as boss connections. At its ends, the cylindrical central part 11 comprises end portions that are adjacent to the domed polar caps 12, 13.

[0049] Such a pressure vessel 10 is produced by reinforcing an inner vessel with an outer layer of fiber reinforcement. FIG. 2 shows this structure of the pressure vessel 10 in a schematic longitudinal section. An outer layer of reinforcing fibers, which comprises radial and axial reinforcements, is wound around an inner vessel 20. The shape of the inner vessel 20 corresponds substantially to the shape of the pressure vessel 10 to be produced, so that the inner vessel 20 comprises a cylindrical central region 21 and two domed polar cap regions 22 and 23, which seal the openings of the cylindrical central region 21. The inner vessel 20 is preferably formed by a plastic liner, the shape of which has been produced for example by an extrusion blow molding method. Such an inner vessel 20 is wound with reinforcing fibers at different angles and with different profiles.

[0050] FIG. 2 shows a fiber reinforcement of a plastic liner 20, as this reinforcement is advantageously configured. It provides a radial reinforcement 30 on the entire liner 20, including the cylindrical central region 21 and the two polar cap regions 22 and 23. Further, an axial reinforcement 40 is provided over the vessel 10. By this ideal fiber alignment in the force direction, the maximum laminate and fiber properties can be exploited.

[0051] Since a radial reinforcement 30 cannot readily be wound continuously on a domed polar cap region, this radial reinforcement 30 is divided into a cylinder reinforcement 30Z and two polar cap reinforcements 30P. The cylinder reinforcement 30Z is located in the cylindrical region of the pressure vessel 10, while each polar cap respectively has a polar cap reinforcement, only a left polar cap reinforcement being provided by way of example with the reference sign 30P in FIG. 2. FIG. 3 shows the left polar cap region 22 of a liner once more on an enlarged scale. The polar cap reinforcement 30P covers the region from the boss connection 14 to the cylindrical central region 21 of the liner and optionally continues into the cylindrical central region 21, as is the case in the embodiment of FIG. 3. The two polar cap reinforcements 30P are preferably produced before the cylinder reinforcement 30Z and before the axial reinforcement 40 is applied. The production of a polar cap reinforcement 30P in a separate winding process will be described below.

[0052] For the separate winding process, a winding tool is used and the polar cap reinforcement 30P is partially generated separately from the liner 20. Such a winding tool 50 is represented schematically in FIG. 4. It includes essentially of two winding plates 51 and 52, which are clamped parallel and at a distance with respect to one another onto a winding axis 53, so that there is a predefined gap 55 with a width x between the plates 51, 52. An annular spacer or winding core 54 is inserted at the bottom of the gap 55. For easy later handling, in one embodiment the inner sides of both winding plates are each furthermore coated with an extensible, thermally stable film 60, 61.

[0053] The gap 55 between the two winding plates 51, 52 is fully wound with circumferential plies, a plurality of circumferential plies being wound next to one another and above one another around the winding core 54 by rotating the winding device 50 about the winding axis 53. The circumferential plies are, for example, in situ impregnated reinforcing fibers or towpregs. This may be done in parallel with a plurality of winding tools, which increases the productivity. FIG. 5 shows a winding tool 50 after the winding process, its gap 55 being filled with a fiber laminate including circumferential windings. This production stage of the resin-impregnated fiber laminate is denoted by the reference sign 30.

[0054] Subsequently, the winding tool 50 is preferably rotated and brought into a position in which the winding plates and therefore the fiber laminate 30 lie horizontally. The winding axis 53 and one winding plate are removed, the fiber laminate 30 lying on the remaining winding plate 51. The film 60, 61 remains on both sides of the fiber laminate 30, while the winding core 54 is optionally also removed.

[0055] A first molding tool 70 with the convex outer contour 73 of the polar cap region of the liner is placed on so that the fiber laminate 30 can bear directly when the remaining winding plate 51 is also removed. In an alternative procedure, the arrangement of FIG. 6 is rotated through 180 so that the fiber laminate 30 lies over the molding tool 70. The fiber laminate 30 is in this case held in a suitable way until it is placed from above on the molding tool 70. The boss 74 may in this case press the winding core 54 and the winding plate 51 away upward so that the fiber laminate 30 can subsequently bear annularly around the boss 74. A boss 74 present on the first molding tool 70 is therefore guided through the central opening 72 in the fiber laminate 30, which has been formed by the winding core 54 and the winding axis 53.

[0056] Alternatively, the liner itself may also be used as the first molding tool. In this case, the boss 74 is a boss connection present on the liner. Consequently, the fiber laminate 30 then annularly surrounds the boss 74, or the boss connection. The dimensions are accordingly matched to one another. The entire arrangement of FIG. 6 is subsequently rotated through 180, or was already rotated when the fiber laminate 30 was placed on from above. This is readily possible because of the bilateral coverage of the fiber laminate 30 by the films 60, 61. FIG. 7 shows the rotated arrangement with the fiber laminate 30, which now bears from above on the first molding tool 70 and the shape of which has to some extent already been adapted to the outer contour 73 of the latter.

[0057] A second molding tool 71 with the desired outer contour of the radial reinforcement is put on from above, as shown by FIG. 7. The concave inner contour 75 of the second molding tool 71 establishes the outer contour of the polar cap reinforcement to be produced. The outer contour of the radial reinforcement may be configured differently according to the vessel design and established by the second molding tool 71. The fiber laminate 30 is then shaped to final contour under pressure between the two molding tools 70, 71 (FIG. 8). This is possible because the radially wound layers of the fiber laminate 30 can slide on one another without rejects being created.

[0058] The fiber laminate 30 is gelled between the molding tools 70, 71 and the films 60, 61, then it is released. The resulting shaped and gelled fiber laminate now forms a polar cap reinforcement, which is denoted by the reference sign 30P in FIG. 8. The molding tools 70,71 do not need to be cleaned because they have not come in contact with the fiber laminate. The films 60, 61 can be peeled off without difficulty.

[0059] As shown in FIG. 3, the polar cap reinforcement 30P generated in this way may be applied onto the polar cap region 22 of a liner by guiding the boss connection 14 through the central opening in the fiber laminate. Preferably, the polar cap reinforcement 30P is adhesively bonded on the liner. The inner film 61 may remain between the liner and the polar cap reinforcement 30P or be removed beforehand. If the liner itself is used as the first molding tool, only the second molding tool 71 is removed and the polar cap reinforcement 30P remains on the liner. In this case, the film 61 remains between the liner and the polar cap reinforcement 30P.

[0060] One or both polar cap regions 22, 23 of a liner 20 are thus provided with prefabricated polar cap reinforcements. In a following winding process, the liner is initially wound with circumferential plies between the two polar cap reinforcements in the cylindrical central region 21 until there is a uniform surface with the polar caps (see FIG. 2). This cylinder reinforcement 30Z together with the two polar cap reinforcements 30P forms the radial reinforcement 30 of the pressure vessel 10. This is followed by the further winding with helical and circumferential plies according to the pressure vessel design, so that an outer reinforcement 40 is obtained. The outer film 60 is preferably removed before the outer reinforcement is applied.

[0061] The original shape of the fiber laminate 30 is simplest when the inner faces of the winding plates 51, 52 are configured perpendicularly to the winding axis 53, so that the distance x between the two winding plates 51, 52 in the radial direction is constant, as is the case with the winding device 50 according to the embodiment of FIG. 4. The wound fiber laminate 30 then has the same wall thickness x everywhere as seen in the axial direction. If this wall thickness is intended to become thicker outward (with an increasing diameter), however, this may be achieved with a winding device 50 having inner faces of the winding plates 51, 52 that correspondingly extend conically, as is shown in FIG. 9a). The distance x between the two winding plates 51, 52 in this case decreases toward the winding core 54. The fiber laminate 30 obtained by the winding then has a greater wall thickness outward than inward, which may be substantially preserved after the deformation between the molding tools 70, 71, as shown by the resulting polar cap reinforcement 30P in FIG. 9b).