MACHINE AND METHOD FOR PRODUCING STRIPS FROM FIBER-REINFORCED PLASTIC COMPOSITE MATERIALS

Abstract

A machine and a method produce strips from a fiber-reinforced plastics composite material. The machine includes a housing through which fibers pass and in which profiled bars are fixedly or rotatably mounted, which are oriented perpendicularly to the passing direction of the fibers and by which forces can be applied alternately to the top and bottom of the fibers and to their coating with a plastics material in order to impregnate the fibers and to consolidate the plastics material between the fibers. The ratio of the average total contact length of all the profiled bars used in the impregnation in millimeters to the number of profiled bars is between 2:1 and 1:400, preferably between 1 and 1:200 and particularly preferably between 1:10 and 1:100.

Claims

1. A machine for producing strips from a fiber-reinforced plastics composite material, comprises a housing (1, 2) through which fibers (F) pass and in which a plurality of profiled bars (3, 4, 5, 6) are fixedly or rotatably mounted, which are oriented perpendicularly to and/or vertically relative to the passing direction of the fibers (F) and by means of which forces can be applied alternately to the top and bottom of the fibers (F) and to their coating with a plastics material (K) in order to impregnate the fibers (F) and to consolidate the plastics material (K) between the fibers (F), wherein the ratio of the average total contact length of all the profiled bars (3, 4, 5, 6) used in the impregnation in millimeters to the number of profiled bars (3, 4, 5, 6) is between 1:1 and 1:200 and particularly preferably between 1:10 and 1:100, wherein the machine comprises at least 10 profiled bars.

2. The machine according to claim 1, wherein the spacing between the profiled bars (3, 4, 5, 6) in both the vertical and horizontal direction is adjustable.

3. The machine according to claim 1, wherein the spacing between the profiled bars (3, 4, 5, 6) in both the vertical and horizontal direction assumes a different value from one profiled bar (3, 4, 5, 6) to the next.

4. The machine according to claim 1, wherein at least some of the profiled bars (3, 4, 5, 6) have a varying diameter over one revolution.

5. The machine according to claim 1, wherein at least one of the profiled bars (3, 4, 5, 6) has a smaller diameter than the others.

6. The machine according to claim 1, wherein at least one of the profiled bars (3, 4, 5, 6) has a greater diameter than the others.

7. The machine according to claim 1, wherein the spacing between adjacent profiled bars (3, 4, 5, 6) is less than the material thickness of the fibers (F) passing through and their coating with plastics material (K).

8. The machine according to claim 1, wherein the profiled bars (3, 4, 5, 6) are indirectly or directly heatable individually or in groups.

9. The machine according to claim 1, wherein the machine is designed such that one or more profiled bars are rotatable continuously or discontinuously and in the direction of the fiber movement or counter thereto.

10. The machine according to claim 1, wherein the machine is designed such that a plurality of strips can be produced thereon simultaneously beside one another or above one another.

11. The machine according to claim 10, wherein the machine is designed such that the strips produced beside one another or above one another can be brought together in another consolidation unit to form a vertically or even horizontally layered strip.

12. The machine according to claim 1, wherein the profiled bars (3, 4, 5, 6) comprise milled recesses, which are designed to shape the strip.

13. A method for producing strips from a fiber-reinforced plastics composite material using the machine according to claim 1, wherein additives are added to the plastics material (K) used.

14. The method according to claim 13, wherein further additives for protection or impregnation are applied to the fiber-reinforced plastics composite material during or after processing.

Description

[0056] FIG. 1a is part of the cross section of a fibre-reinforced plastics composite after the impregnation.

[0057] FIG. 1b is a cross section of the fibre-reinforced plastics composite according to FIG. 1a, after additional consolidation.

[0058] FIG. 2 is a section through the part of a machine for impregnating and consolidating strips of fibre-reinforced plastics composite material.

[0059] FIG. 3 is detail of the machine for impregnating and consolidating strips of fibre-reinforced plastics composite material from FIG. 2.

[0060] FIG. 1a schematically shows a cross section through a fibre-reinforced plastics composite material. The part of the cross section shown is so small that only six F are visible. These F are already all fully “impregnated”, i.e. their entire outer surface is already wetted with at least one thin layer of the liquefied plastics material K. The spaces between the F are already largely filled with plastics material K and are only interrupted by air-filled cavities H at a few points.

[0061] Because the air is under increased pressure due to the processing of the heated material, it expands when cooling, meaning that the structure of the plastics material, which is not yet completely solidified, is damaged and therefore its adhesive strength and tear resistance is reduced.

[0062] FIG. 1b shows that the machine according to the invention has driven the cavities H out of the plastics material K by said machine having processed the strip from fibre-reinforced plastics composite material using the profiled bars 3, 4, 5, 6 according to the invention. This process is called consolidation. The ideal state is reached when all the F are surrounded by a homogeneous mass of plastics material K.

[0063] In FIG. 2, the housing of a machine according to the invention consists of two side walls 1, one of which has been removed in the figure so that the connecting middle part 2 of the housing is visible. At the input of the machine, the strip made of the F first passes through a nozzle 10, which applies plastics material K to all sides of the strip. The coated strip then wraps around a plurality of profiled bars 3, 4, 5, 6. The heating apparatuses which heat and thus liquefy the plastics material K and the heaters for the profiled bars 3, 4, 5, 6 are not shown.

[0064] In the variant shown, the middle part 2 of the housing is curved upwards at its ends in the shape of a basin, such that it collects plastics material K that drips off and is not required and drains it away by means of guides (not shown here).

[0065] In FIG. 2, the strip first runs around a cylindrical profiled bar 3, which is mounted on the side walls 1 of the machine at the fastening point 31. The relatively large diameter of this profiled bar 3 provides a relatively long path distance of the strip on the cylindrical outer surface. As a result, the plastics material K is evenly distributed on and between the F of the strip.

[0066] The strip next runs over a ribbed profiled bar 4. The rib on said profiled bar is visible as a “lug”, which is attached to a cylindrical main body. This rib provides a force pulse, which acts on the still viscous plastics material K and between the F in the fibre-reinforced plastics composite and thus drives the cavities H that are still found therein further towards the outside.

[0067] The following, elliptical profiled bar 5 exerts two additional force pulses per revolution by means of its two more pointed regions. The polygonal profiled bar 6 generates four pulses by means of its four somewhat rounded corners.

[0068] In FIG. 2, it is clear at first glance that, for the profiled bars 4, 5 and 6, the effective diameter fluctuates considerably in relation to the fastening points 41, 51 and 61 over one revolution. As a result, pressure pulses are exerted on the impregnation of the F in a welcome manner.

[0069] As a result of this geometry, however, the part of the strip located in the machine would be lengthened or shortened. As a result, additional forces that are not effectively controllable could be exerted on the strip at the adjacent profiled bars, or the strip would briefly lift off from the adjacent profiled bars. In order to prevent these effects, in the configuration of the machine according to the invention as shown in FIG. 2, two cylindrical profiled bars 3 are not directly connected to the side wall 1, but instead are vertically movably mounted. To do this, they are fastened to auxiliary rods 8, which extend as far as the upper edge of the side wall 1 and are articulated to pivotable dancing levers 9 at this point. Only the dancing levers 9 are pivotally connected to the side wall 1. Depending on the relevant angular position of the profiled bars 4, 5 and 6, they raise and lower the two movably mounted profiled bars 3. In this way, they compensate for the geometric changes in length resulting from the non-circular profile of the profiled bars 4, 5 and 6.

[0070] FIG. 2 shows an embodiment of a machine according to the invention comprising 7 profiled bars 3, 4, 5, 6, each of which drives further cavities H filled with air out of the plastics material K. Depending on the desired processing speed and the permissible degree of remaining cavities H, configurations comprising up to 100 profiled bars 3, 4, 5, 6 are useful. According to the invention, the ratio of the average contact length of all the profiled bars used in the impregnation in millimetres to the number of profiled bars 3, 4, 5, 6 is between 2 and 1:400, preferably between 1 and 1:200 and particularly preferably between 1:10 and 1:100.

[0071] At the end of the machine on the right as shown, the strip is guided upwards out of the basin-shaped middle part 2 of the housing. It then passes through two cylindrical profiled bars 3 arranged very close to one another. The spacing between the outer surfaces of these two profiled bars 3 is less than the thickness of the strip of fibre-reinforced plastics composite material that is then achieved, such that the profiled bars 3 operate as a calender 7. In this way, the plastics material K is compressed for a final time and the strip is brought to the required thickness.

[0072] In FIG. 2, the devices of the machine according to the invention for rolling up the strip, for liquefying the plastics material, the heating apparatuses and coolers and also the rollers for the finished strips are not shown because they are well known from the available prior art in many variants.

[0073] FIG. 3 is an enlarged detail of the first profiled bar 3 in the processing direction of the F from FIG. 2. The relatively large diameter of this profiled bar 3 provides a relatively long path distance of the strip on the cylindrical outer surface 11. The sum of the path distances of the strip on all the profiled bars 3, 4, 5, 6 forms the total contact length of the strip with all the profiled bars 3, 4, 5, 6 used during the impregnation. According to the invention, the ratio of the average total contact length of all the profiled bars used in the impregnation in millimetres to the number of profiled bars 3, 4, 5, 6 is between 2 and 1:400, preferably between 1 and 1:200 and particularly preferably between 1:10 and 1:100.

LIST OF REFERENCE SIGNS

[0074] F fibres [0075] H cavities in the plastics material K [0076] K plastics material for impregnating the F [0077] 1 side wall of the housing of the machine [0078] 2 middle part of the housing of the machine [0079] 3 profiled bar, cylindrical, mounted between the side walls 1 and 2 [0080] 31 fastening point or rotational axis of the profiled bar 3 [0081] 4 profiled bar, ribbed, mounted between the side walls 1 and 2 [0082] 41 fastening point or rotational axis of the profiled bar 4 [0083] 5 profiled bar, elliptical, mounted between the side walls 1 and 2 [0084] 51 fastening point or rotational axis of the profiled bar 5 [0085] 6 profiled bar, polygonal, mounted between the side walls 1 and 2 [0086] 61 fastening point or rotational axis of the profiled bar 6 [0087] 7 profiled bars 3, arranged as a calender [0088] 8 auxiliary rods for movably mounting profiled bars 3 [0089] 9 dancing lever for guiding a profiled bar 3 over the auxiliary rods 8 [0090] 10 nozzle for applying the plastics material K to the F [0091] 11 path distance of the strip on the cylindrical outer surface of the profiled bar