METHOD AND STRAND-DRAWING DEVICE FOR PRODUCING LEAF SPRINGS IN FIBER COMPOSITE CONSTRUCTION

Abstract

A method for producing leaf springs in fiber composite construction in a desired shape of the leaf springs, the method including the following steps: strand-drawing a fiber material from a fiber supply store into an injection box, which is designed to continuously impregnate a respective section of the fiber material within an injection chamber of the injection box under a chamber overpressure with at least one matrix material during the strand drawing of the fiber material; pulling the fiber material strand impregnated with the matrix material out of the injection box, and subsequently, conveying the fiber material strand impregnated with matrix material to a heating device, where each of the conveyed sections of the fiber material strand impregnated with the matrix material is at least partially cured; and forming the fiber material strand reinforced with the matrix material into the desired shape of the leaf springs. The invention further relates to an associated strand-drawing device.

Claims

1. A method for producing leaf springs (2) in fibre composite construction into a desired shape of the leaf springs (2), comprising the steps: strand-drawing a fibre material (4) from a fibre supply store (3) into an injection box (6), which is designed to continuously impregnate a respective section of the fibre material (4) within an injection chamber (6a) of the injection box (6) under a chamber overpressure with at least one matrix material during the strand-drawing of the fibre material (4), wherein the matrix material is injected from outside the injection box (6) into the injection chamber (6a) or is pressed in with pressure, drawing the fibre material strand (4a) impregnated with the matrix material out of the injection box (6), and subsequently, conveying the fibre material strand (4a) impregnated with matrix material to a heating device (7), where the respective conveyed section of the fibre material strand (4a) impregnated with the matrix material is at least partially cured, and forming the fibre material strand (4a) reinforced with the matrix material into the desired shape of the leaf springs (2).

2. The method according to claim 1, wherein the section, drawn out of the injection box (6), of the fibre material strand (4a) impregnated with the matrix material is conveyed before its complete curing to a forming tool (8) which is designed to give the desired shape of the leaf spring (2) to the section of the fibre material strand (4a), reinforced with the matrix material, which is respectively drawn continuously out of the injection box (6).

3. The method according to claim 2, wherein the section of the fibre material strand (4a), impregnated with the matrix material, which is drawn out of the injection box (6) is drawn continuously through a cavity (8a) of the forming tool (8) defining the cross-section configuration of the desired shape of the leaf spring (2), and subsequently the fibre material strand (4a) is completely cured to a straight leaf spring (2) in the heating device (7).

4. The method according to claim 2, wherein the section of the material strand (4a), impregnated with the matrix material, which is drawn out from the injection box (6) is drawn continuously through a cavity (8a) of the forming tool (8) defining a cross-section configuration of the desired shape of the leaf spring (2), subsequently the fibre material strand (4a) is heated in the heating device (7) to an at least partially or completely cured fibre material strand (4a) and subsequently the at least partially or completely cured fibre material strand (4a) is warmed again and is then shaped and/or pressed in a forming tool (8b) to a leaf spring (2) having the desired shape.

5. The method according to claim 2, wherein the section of the fibre material strand (4a), impregnated with the matrix material, which is drawn out from the injection box (6) is drawn continuously through a cavity (8a) of the forming tool (8) defining the cross-section configuration of the desired shape of the leaf spring (2), subsequently the fibre material strand (4a) is heated in the heating device (7) to an only partially cured fibre material strand (4a), and subsequently the only partially cured fibre material strand (4a) is shaped, free of re-warming, in a forming tool (8c) to a leaf spring (2) having the desired shape and, after the shaping, a complete curing of the leaf spring (2) having the desired shape takes place.

6. The method according to claim 2, wherein the section of the fibre material strand (4a), impregnated with the matrix material, which is drawn out of the injection box (6), is drawn continuously through a cavity (8a) of the forming tool (8) defining the cross-section configuration of the desired shape of the leaf spring (2), subsequently the fibre material strand (4a) is heated in the heating device (7) to an at least partially or completely cured fibre material strand (4a), and subsequently the only partially cured fibre material strand (4a) or the completely cured and re-warmed fibre material strand is shaped by means of a radius pultrusion method to a leaf spring (2) with a curved desired shape.

7. The method according to claim 1, wherein the matrix material comprises at least one polyurethane material or a two-stage curing epoxy resin.

8. A strand-drawing device for producing leaf springs (2) in fibre composite construction, having a fibre supply store (3) with at least one fibre material stored therein, a traction device (5) which is designed to draw the fibre material continuously out of the fibre supply store (3), an injection box (6) which is designed to continuously impregnate a respective section of the fibre material, drawn through the injection box (6) by the traction device (5), within an injection chamber (6a) of the injection box (6) under a chamber overpressure, with at least one matrix material injected from outside the injection box (6) into the injection chamber (6a) or pressed in under pressure during the strand-drawing of the fibre material (4), and a heating device (7) which is designed for the at least partial curing of a section of the fibre material strand (4a), impregnated with the matrix material, respectively conveyed to the heating device (7) by means of the traction device (5), and a forming tool (8) which is designed to shape a respective at least partially cured section of the fibre material strand (4a), reinforced with the matrix material, into a desired shape of the respective leaf spring (2).

9. The strand-drawing device according to claim 8, wherein the forming tool (8) has a cavity (8a) which is designed to define the desired shape of the leaf spring (2) for the section of the fibre material strand (4a), impregnated with the matrix material, drawn continuously out of the injection box (6), with regard to its cross-section configuration, and the strand-drawing device (1) has a control device (9) which is designed to control the heating device (7) and the traction device (5) in such a way that the fibre material strand (4a), after its exit from the cavity (8a), is cured completely to a straight leaf spring (2) in the heating device (7).

10. The strand-drawing device according to claim 8, wherein the forming tool (8) has a cavity (8a) which is designed to define the desired shape of the leaf spring (2) for the section of the fibre material strand (4a), impregnated with the matrix material, which is drawn continuously out of the injection box (6), with regard to its cross-section configuration, and the strand-drawing device (1) has a control device (9) which is designed to control the heating device (7) and the traction device (5) in such a way that the at least partially or completely cured fibre material strand (4a), after its exit from the heating device (7), is warmed again at a warming device (11) and then in a further forming tool (8b) is shaped and/or pressed to a leaf spring (2) having the desired shape.

11. The strand-drawing device according to claim 8, wherein the forming tool (8) has a cavity (8a) which is designed to define the desired shape of the leaf spring (2) for the section of the fibre material strand (4a), impregnated with the matrix material, which is drawn continuously out of the injection box (6), with regard to its cross-section configuration, and the strand-drawing device (1) has a control device (9) which is designed to control the heating device (7) and the traction device (5) in such a way that the fibre material strand (4a) is heated in the heating device (7) to an only partially cured fibre material strand (4a), and subsequently the only partially cured fibre material strand (4a) is shaped, free of re-warming, in a further forming tool (8c) to a leaf spring (2) having the desired shape and, after the shaping, a complete curing of the leaf spring (2) having the desired shape takes place.

12. The strand-drawing device according to claim 8, wherein the forming tool (8) has a cavity (8a) which is designed to define the desired shape of the leaf spring (2) for the section of the fibre material strand (4a), impregnated with the matrix material, which is drawn continuously out of the injection box (6), with regard to its cross-section configuration, and the strand-drawing device (1) has a control device (9) which is designed to control the heating device (7) and the traction device (5) in such a way that the fibre material strand (4a) is heated in the heating device (7) to an at least partially or completely cured fibre material strand (4a), and subsequently the only partially cured fibre material strand (4a) or the completely cured and re-warmed fibre material strand (4a) is shaped by means of a radius-pultrusion device (12) of the strand-drawing device (1) to a leaf spring (2) with a curved desired shape.

Description

[0035] Several example embodiments of the invention are explained in further detail by way of example in the following description with reference to the enclosed schematic figures. Concrete features of this example embodiments, irrespective of in which concrete context they are mentioned, if applicable also considered individually or in other combinations, can represent general features of the invention.

[0036] There are shown:

[0037] FIG. 1 a flowchart of a basic form of a method according to the invention,

[0038] FIG. 2 a schematic illustration of a first variant embodiment of a strand-drawing device according to the invention,

[0039] FIG. 3 a schematic illustration of a second variant embodiment of a strand-drawing device according to the invention,

[0040] FIG. 4 a schematic illustration of a third variant embodiment of a strand-drawing device according to the invention, and

[0041] FIG. 5 a schematic illustration of a fourth variant embodiment of a strand-drawing device according to the invention.

[0042] In FIG. 1 a basic form of the method according to the invention is shown by means of a flowchart. The method serves for the producing of leaf springs 2 in fibre composite construction into a desired shape of the leaf springs 2, having the first step S1 of strand-drawing of a fibre material 4 out of a fibre supply store 3 into an injection box 6. The injection box 6 is designed to continuously impregnate a respective section of the fibre material 4 in a second step S2 within an injection chamber 6a of the injection box 6 under a chamber overpressure with at least one matrix material during the strand-drawing of the fibre material 4.

[0043] In the first part of a third step S3.1, a drawing out takes place of the fibre material strand 4a, impregnated with the matrix material, out of the injection box 6, and subsequently in the second part of a third step S3.2 a conveying of the fibre material strand 4a, impregnated with the matrix material, to a heating device 7.

[0044] At the heating device 7, in a fourth step S4 of the method, an at least partial curing of the respective conveyed section of the fibre material strand 7a, impregnated with the matrix material, takes place.

[0045] Finally, in a fifth step of the method, a forming of the fibre material strand 4a, reinforced with the matrix material, into the desired shape of the leaf springs 2 takes place.

[0046] In FIG. 2 to FIG. 5, various embodiment variants of strand-drawing devices 1 are illustrated. These strand-drawing devices 1 are designed for producing leaf springs 2 in fibre composite construction, having a fibre supply store 3 with at least one fibre material 4 stored therein, a traction device 5, which is designed to draw the fibre material 4 continuously out of the fibre supply store 3, an injection box 6, which is designed to continuously impregnate a respective section of the fibre material 4, which is drawn by the traction device 5 through the injection box 6, within an injection chamber 6a of the injection box 6 under a chamber overpressure with at least one matrix material during the strand-drawing of the fibre material 4, and a heating device 7, which is designed for the at least partial curing of a section of the fibre material strand 4a, impregnated with the matrix material, which is conveyed respectively to the heating device 7 by means of the traction device 5, and a forming tool 8, which is designed to shape a respective, at least partially cured section of the fibre material strand 4a, reinforced with the matrix material, into a desired shape of the respective leaf spring 2.

[0047] In the first variant embodiment according to FIG. 2, the forming tool 8 has a cavity 8a, which is designed to define the desired shape of the leaf spring 2 for the section of the fibre material strand 4a, impregnated with the matrix material which is drawn out continuously from the injection box 6, with regard to its cross-section configuration, and the strand-drawing device 1 has a control device 9 which is designed to control the heating device 7 and the traction device 5 in such a way that the fibre material strand 4a, after its exit from the cavity 8a, is completely cured in the heating device 7 to a straight leaf spring 2. After a complete curing, the respective end-side leaf spring 2 can be separated from the fibre material strand 4a by means of a separating device 10a, such as a saw for example.

[0048] In the second variant embodiment according to FIG. 3, the forming tool 8 has a cavity 8a which is designed to define the desired shape of the leaf spring 2 for the section of the fibre material strand 4a, impregnated with the matrix material, which is drawn out continuously from the injection box 6, with regard to its cross-section configuration, and the strand-drawing device 1 has a control device 9, which is designed to control the heating device 7 and the traction device 5 in such a way that the at least partially or completely cured fibre material strand 4a, after its exit from the heating device 7, is warmed again at a warming device and is then shaped and/or pressed in a further forming tool 8b to a leaf spring having the desired shape. In the case of the present example embodiment, the warming device 11 is arranged in traction direction after the traction device 5 and after the separating device 10. In corresponding modifications of this second variant embodiment, the warming device 11 can, however, be arranged for example after the traction device 5 and before the separating device 10, i.e. between the traction device 5 and before the separating device 10 or if applicable also even before the traction device 5 and before the separating device 10.

[0049] In the third variant embodiment according to FIG. 4, the forming tool 8 has a cavity 8a, which is designed to define the desired shape of the leaf spring 2 for the fibre material strand 4a, impregnated with the matrix material, which is drawn out continuously from the injection box 6, with regard to its cross-section configuration, and the strand-drawing device 1 has a control device 9, which is designed to control the heating device 7 and the traction device 5 in such a way that the fibre material strand 4a is heated in the heating device 7 to an only partially cured fibre material strand 4a, and subsequently the only partially cured fibre material strand 4a is shaped, free of re-warming, to a leaf spring 2 having the desired shape in a further forming tool 8c, and a complete curing of the leaf spring 2, having the desired shape, only takes place after the shaping.

[0050] In the fourth variant embodiment according to FIG. 5, the forming tool 8 has a cavity 8a, which is designed to define the desired shape of the leaf spring 2 for the section of the fibre material strand 4a, impregnated with the matrix material, which is drawn out continuously from the injection box 6, with regard to its cross-section configuration, wherein the strand-drawing device 1 has a control device 9 which is designed to control the heating device 7 and the traction device 5 in such a way that the fibre material strand 4a is heated to an at least partially or completely cured fibre material strand 4a in the heating device 7, which is movable on a circular path, and subsequently the only partially cured fibre material strand 4a or the completely cured and re-warmed fibre material strand 4a is shaped to a leaf spring 2 with a curved, in particular circular-arc-shaped, desired shape by means of a radius pultrusion device 12, which moves the heating device 7 together with the forming tool 8 or respectively the cavity 8a.

LIST OF REFERENCE NUMBERS

[0051] 1 strand-drawing device [0052] 2 leaf springs [0053] 3 fibre supply store [0054] 4 fibre material [0055] 4a fibre material strand [0056] 5 traction device [0057] 6 injection box [0058] 6a injection chamber [0059] 7 heating device [0060] 8 forming tool [0061] 8a cavity [0062] 9 control device [0063] 10 separating device [0064] 11 warming device [0065] 12 radius pultrusion device