METHOD AND APPARATUS FOR PRODUCING A PLASTIC PROFILE HAVING A REINFORCEMENT

Abstract

In the pultrusion of reinforced plastic profiles in strand form, the strands of the reinforcement are brought together in a positioning device and subsequently embedded in the plastic. The pulling of the strands of the reinforcement through the positioning device leads to an unwanted contraction and uncontrolled positioning of the reinforcement in the plastic profile. The invention envisages forming the positioning device by multiple successive positioning means, of which at least some positioning means can be periodically moved forward in the direction of production and also moved back counter to the direction of production. As a result, there is an alternating tensioning and compression of individual regions of the reinforcement. This makes exact positioning of the reinforcement in the plastic profile possible and prevents contraction of the reinforcement.

Claims

1. An apparatus for producing a plastic profile (10, 33) having a reinforcement (11), comprising: a closed mold (23, 32), completely surrounding the plastic profile (10, 33); at least one positioning device (14), for the reinforcement (11) of the plastic profile (10, 33), arranged upstream of the mold (23, 32) in the direction of production (13) of the plastic profile (10, 33) the positioning device (14) having multiple successive positioning means (15, 16, 17, 18); and at least one of the positioning means (15, 16, 17, 18) being movable back and forth in relation to at least one other positioning means (15, 16, 17, 18).

2. The apparatus as claimed in claim 1, wherein each positioning means (15, 16, 17, 18) is formed like an orifice plate and/or each positioning means (15, 16, 17, 18) has a passage (28, 29, 30, 31) for the reinforcement (11) and the passages (28, 29, 30, 31) in the positioning means (15, 16, 17, 18) following one another in the direction of production (13) become smaller in the direction of production (13).

3. The apparatus as claimed in claim 1, wherein the positioning means (15, 16, 17, 18) that is movable back and forth is periodically moved independently of the other positioning means (15, 16, 17, 18).

4. The apparatus as claimed in claim 1, further comprising at least one pulling device (24) that can be periodically moved back and forth, wherein the at least one pulling device (24) follows the mold (23, 32) in the direction of production (13).

5. The apparatus as claimed in claim 3, wherein the positioning means (15, 16, 17, 18) that is movable back and forth is periodically moved independently of the other positioning means (15, 16, 17, 18) by a drive or actuator of its own.

6. The apparatus as claimed in claim 4, wherein the pulling device (24) has a cooling arrangement and/or consists of multiple gripper parts that can be moved together and apart and in the pressed-together state completely grip around the plastic profile (10, 33) to be produced.

7. A method for producing a plastic profile (10, 33) having a reinforcement (11), comprising: passing the reinforcement (11) with plastic (12) embedding the reinforcement through a mold (23, 32) in the direction of production (13); forming the mold (32) with multiple mold portions (34) following one another in the direction of production (13) and respectively having a molding passage (35) corresponding to the cross section of the plastic profile (10, 33) to be produced; and displacing the mold portions (34) such that the longitudinal directions (36) of the molding passages (35) lie on a longitudinal center axis of the plastic profile (10) to be produced and/or run tangentially with respect to the longitudinal center axis (37) of the plastic profile (33) to be produced to achieve a desired shape of the plastic profile (10, 33).

8. The method as claimed in claim 7, wherein the mold portions (34) are displaced in such a way that the inclinations of the longitudinal directions (36) of the molding passages (35) change.

9. The method as claimed in claim 7, wherein the mold portions (34) are displaced in such a way that, in the case of plate-like mold portions (34), points of the molding passages (35) that lie in the center of the plate lie on the longitudinal center axis (37) of each plastic profile (10, 33) to be produced.

10. The method as claimed in claim 8, wherein the mold portions (34) are displaced in such a way that, in the case of plate-like mold portions (34), points of the molding passages (35) that lie in the center of the plate lie on the longitudinal center axis (37) of each plastic profile (10, 33) to be produced.

11. An apparatus for producing a plastic profile (10, 33) having a reinforcement (11), comprising a mold (32) that brings the plastic profile (10, 33) with the reinforcement (11) lying therein into the desired form, wherein the mold (32) is formed by multiple mold portions (34) following one another in a direction of production (13) and having molding passages (35) corresponding to the cross section of the plastic profile (10, 33) to be produced, and the size of each molding passage (35) changes in the longitudinal direction (36) of the same or in the direction of production (13) of the plastic profile (10, 33).

12. The apparatus as claimed in claim 11, wherein the mold portions (34) are formed as mold plates, the molding passages (35) that extend transversely through the mold plates being smallest approximately in the center of the respective mold plate and increasing in size increasingly toward opposing main surfaces of the molding plates.

13. The apparatus as claimed in claim 11, wherein the mold portions (34) can be tilted, by the longitudinal direction (36) of the molding passage (35) in the respective mold portion (34), namely the respective mold plate.

14. The apparatus as claimed in claim 13, wherein the respective mold plate is variable in inclination.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The inventions are explained in more detail below on the basis of the drawing, in which:

[0026] FIG. 1 shows a schematic side view of an apparatus for producing a reinforced plastic profile,

[0027] FIG. 2 shows a graphic representation of the sequence of movements over time of individual components of the apparatus of FIG. 1,

[0028] FIG. 3 shows a schematically represented section through a mold for producing an arcuate plastic profile, and

[0029] FIG. 4 shows the mold of FIG. 3 in an arrangement for producing a straight plastic profile.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] FIG. 1 shows the essential components of an apparatus for producing a reinforced plastic profile. This apparatus is a pultrusion apparatus for a plastic profile 10 with a reinforcement 11. The reinforcement 11 is completely embedded in a plastic 12, which may be both a thermoset and a thermoplastic.

[0031] The reinforcement 11 may be formed by a multiplicity of uninterrupted strands, but also a nonwoven, woven and/or knitted fabric. The reinforcement 11 may also consist of combinations of strands, nonwoven, knitted and/or woven fabrics. Preferably, the reinforcement 11 is formed by high-strength synthetic, glass and/or carbon fibers or strands.

[0032] The plastic profile 10 may have any desired cross sections. In the longitudinal direction, which corresponds to the direction of production 13 of the reinforced plastic profile 10, the plastic profile 10 may either run in a straight line, as represented in FIGS. 1 and 4, or else be arcuate, according to FIG. 3. In addition, the plastic profile 10 may have any other desired shapes in the longitudinal direction. The invention is therefore neither restricted to the cross section nor to the shape of the plastic profile 10. In particular, non-straight shapes of the plastic profile 10 may be both confined to one plane (two-dimensional) or else be three-dimensional.

[0033] The apparatus shown has multiple components following one another at a distance in the direction of production 13. At the beginning of the apparatus there is a positioning device 14 for the reinforcement 11. According to the invention, the positioning device 14 is formed by multiple positioning means following one another at a distance in the direction of production 13. The positioning device 14 shown is formed by four successive positioning means 15, 16, 17 and 18. However, the invention is not restricted to this. In the simplest case, the positioning device 14 need only have two positioning means, and it may also be formed by more than four positioning means 15, 16, 17, 18.

[0034] The positioning device 14 is followed in the direction of production 13 by an impregnating device 25, for feeding the liquid plastic 12 to the reinforcement 11 bundled in the positioning device 14, a heating device 19 with a cooled inlet 20 at the beginning, a gel zone region 21 and a final reaction region 22. The heating device 19 with the cooled inlet 20, the gel zone region 21 and the final reaction region 22 together form an annular, closed mold 23, surrounding the plastic profile 10, of the apparatus, for which purpose they may possibly be completely or partially combined to form a single unit or possibly also multiple units.

[0035] At a distance downstream of the final reaction region 22 of the mold 23, seen in the direction of production 13, there is a pulling device 24, which pulls the plastic profile 10 through the positioning device 14, the impregnating device 25 and the mold 23. The pulling device 24 also serves for keeping the reinforcement 11 taut during the entire operation of producing the plastic profile 10, by the individual component parts, for example strands, of the reinforcement 10 being subjected to a restraining force, acting counter to the holding force of the pulling device 24, of a device for unrolling the strands that is not shown in the figures.

[0036] In the case of the apparatus shown here, the impregnating device 25 is assigned a discharge device 26 for excess resin that is only schematically represented. A further discharge device 27 is assigned to the gel zone region 21. This discharge device 27 serves for discharging low-viscosity resin from the already initiated reaction.

[0037] In the case of the apparatus shown here, all four positioning means 15 to 18, the impregnating device 25, the individual components of the mold 23 and the pulling device 24 can be moved, in particular can be moved back and forth, in the direction of production 13 and counter to the direction of production 13 for a short time (periodically) at preferably regular time intervals. For this purpose, each positioning means 15 to 18, the impregnating device 25, the mold 23 and the pulling device 24 are particularly assigned a motion element that is not shown in the figures. This may be a reversible linear drive, the movement axis of which runs in the direction of production 13. It is also conceivable to bring about the back-and-forth movements of the positioning means 15 to 18, the impregnating device 25, the mold 23 and/or the pulling device 24 by actuators, for example piezos.

[0038] A conceivable alternative refinement of the apparatus envisages moving the mold 23 as a whole back and forth. Then, the individual components of the mold 23 carry out movements simultaneously. For this purpose, the mold 23 may be formed by components that are joined together and not spaced apart from one another, by the heating device 19, the gel zone region 21 and the final reaction region 22 following one another directly.

[0039] The individual positioning means 15 to 18 of the positioning device 14 are formed like orifice plates. For this purpose, each positioning means 15, 16, 17, 18 consists of a plate running transversely with respect to the direction of production 13. The plates may be of the same thickness, or else have different thicknessesas in the exemplary embodiment shownby the positioning means 17 and 18 being thicker than the positioning means 15 and 16, to be precise approximately twice as thick. Each of the plate-like positioning means 15 to 18 has a passage 28, 29, 30, 31. The reinforcement 11 is led through the passages 28, 29, 30 and 31 of the positioning means 15, 16, 18 in the direction of the impregnating device 25. The passages 28 to 31 of the individual positioning means 15 to 18 are of different sizes. In the direction of production 13, the passages 28 to 31 of the positioning means 15 to 18 become increasingly smaller. The first positioning means 15 in the direction of production 13 accordingly has the largest passage 28, while the last positioning means 18 before the impregnating device 25, seen in the direction of production 13, has the smallest passage 31. The orifice-plate-like form of the positioning means 15 to 18, with the passages 28 to 31 becoming increasingly smaller in the direction of production 13, has the effect that the reinforcement 11 is bundled by the positioning means 15 to 18 in the direction of production 13 and increasingly compacted, whereby, in the direction of production 13, the reinforcement 11 is brought together in a funnel-like manner in the direction of the impregnating device 25.

[0040] In the exemplary embodiment shown in FIG. 1, the positioning means 15 to 18 are spaced equally apart from one another. The intermediate spaces between successive positioning means 15 to 18 are approximately the same size. In the exemplary embodiment shown, the intermediate spaces between two respective positioning means 15 to 18 are approximately the thickness of the positioning means 17 or 18.

[0041] The pulling device 24 is formed such that it can be released from the finished plastic profile 10. For this purpose, the pulling device 24 has, for example, grippers that can be moved together and apart. When the pulling device 24 securely holds the plastic profile 10, it can be moved forward by the pulling device 24 in the direction of production 13. When the pulling device 24 is released from the plastic profile 10, the pulling device 24 can be moved back counter to the direction of production 13.

[0042] The pulling device 24 may possibly be provided with a cooling arrangement. The cooling arrangement of the pulling device 24 is provided in particular whenever it is intended to produce with the apparatus a plastic profile 10 in which the reinforcement 11 is embedded in a thermoplastic material 12. The pulling device 24 may be designed in particular for producing a plastic profile 10 from a thermoplastic material 12 and also for compressing the plastic profile 10 in the circumferential direction. Then, the demolding of the plastic profile 10 takes place in the compressible pulling device 24. This demolding takes place after a calibration of the plastic profile 10. For this purpose, the pulling device 24 may be dividably formed, by consisting of two or more parts, in particular press parts, that can be moved together and apart transversely with respect to the direction of production 13. With the press parts of the pulling device 24 moved together, there takes place a demolding under pressure or calibration of the plastic profile 10 surrounded all around by the press parts. With the press parts moved apart, the pulling device 24 is detached from the lateral surface of the plastic profile 10, whereby the pulling device 24 can be moved back counter to the direction of production 13 without contacting the lateral surface of the plastic profile 10.

[0043] Linear drives or actuators for moving the pulling device 24 forward and back are not represented in FIG. 1. Similarly, FIG. 1 does not include any representation of such drives or actuators for moving the gel zone region 21, the final reaction region 22 and the heating device 19 of the mold 23 and also the impregnating device 25. Such linear drives may be formed in a way known per se. The actuators may consist of piezos. The latter lead to relatively small traveling distances. By contrast, linear drives allow greater traveling distances, to be precise of any desired length.

[0044] The method according to the invention is described in more detail below with reference to FIGS. 1 and 2.

[0045] In the following description of the method, it is assumed that all four positioning means 15 to 18, the impregnating device 25, all parts of the mold 23 and the pulling device 24 can be moved back and forth in the direction of production 13 and counter to the direction of production 13 periodically by the same distance in each case, the movement of the positioning means 15 to 18, the impregnating device 25, the parts of the mold 23 and the pulling device 24 being phase-shifted. During the movement back and forth of the aforementioned movable parts of the apparatus, the reinforcement 11 is kept taut over the entire length.

[0046] In FIG. 2, the sequences of movements are represented in a time-distance diagram. The time t is plotted on the x axis and the distance s is plotted on the y axis. In the case of the time-distance diagram shown here, it is assumed that the positioning means 15 and 16 on the one hand and the positioning means 17 and 18 on the other hand are moved simultaneously. In the time-distance diagram of FIG. 2, the sequences of movement of the positioning means 15 and 16, the positioning means 17 and 18, the impregnating device 25, the heating device 19 with the cooled inlet 20, the gel zone region 21, the final reaction region 22 and the pulling device 24 are represented one above the other from the bottom upward. The opening of the grippers of the pulling device 24 is represented in vertical regions. Following thereafter in time is the time period in which the grippers of the pulling device 24 are open, represented by a cross-hatched bar. Represented alongside by vertical hatching is the phase of the closing of the grippers. The (white) regions of a longer time between the vertical bars for the opening of the pulling device 24, the open pulling device 24 and the closing of the pulling device 24, represent time phases in which the grippers of the pulling device 24 are closed. Each of these time phases is greater by a multiple than the time phase in which the grippers of the pulling device 24 open, close and are open.

[0047] The direction of the distance s represented on the y axis in FIG. 2 corresponds to the movement of the individual components of the apparatus counter to the direction of production 13. Accordingly, a movement in the direction of the y axis that is represented in FIG. 2 concerns a movement counter to the direction of production 13 of the plastic profile 10.

[0048] Represented at the top in FIG. 2 is the sequence of movements of the pulling device 24. Accordingly, with its grippers open, the pulling device 24 moves relatively quickly counter to the direction of production 13. During the subsequent closing of the grippers of the pulling device 24, the pulling device 24 is stationary. Subsequently, with the grippers closed, the pulling device 24 is slowly moved forward in the direction of production 13, to be precise approximately in half the time in which the pulling device 24 is closed during a respective movement cycle. The movement described above of the pulling device 24 is repeated for each movement cycle.

[0049] The movements of all the other components of the apparatus, to be specific the final reaction region 22, the gel zone region 21, the heating device 19 with the cooled inlet 20, the impregnating device 25, the positioning means 17 and 18 and the positioning means 15 and 16, proceed in accordance with the same pattern of movements, but are phase-shiftedas can be seen from FIG. 2to be precise with respect to the next-following device, by half the time in which the grippers of the pulling device 24 are opened, are open and are closed (vertical bars of FIG. 2). The final reaction region 22, upstream of the pulling device 24, is stationary while the pulling device 24 is opened, is open and is closed. Once the pulling device 24 is closed, the final reaction region 22 is moved in the direction of production 13, to be precise always approximately less than half the time in which the pulling device 24 is closed. After a brief pause, the final reaction region 22 is then moved back counter to the direction of production 13, to be precise at the same speed and by the same distance as the final reaction region 22 was previously moved forward in the direction of production 13. The same movements are carried out with the same offset in time by the gel zone region 21, the heating device 19 with the cooled inlet 20, the impregnating device 25, the positioning means 17 and 18 and the positioning means 15 and 16.

[0050] It is clear from FIG. 2 that the same movements of all the components of the apparatus apart from the pulling device 24 follow one another with an offset in time, but partially overlap one another. The time offset is chosen such that the movement of the positioning means 15 and 16 at the beginning of the apparatus is offset with respect to the movement of the final reaction region by half the time in which the grippers of the pulling device 24 are closed.

[0051] As a departure from the representation of FIG. 2, all four positioning means 15 to 18 may also be moved back and forth one after the other independently of one another with a small time offset. It is also conceivable to move only two positioning means, for example the positioning means 15 and 17 or the positioning means 16 and 18, periodically back and forth along the plastic profile 10, while the other two positioning means 15, 17 or 16, 18 are not moved back and forth.

[0052] The phased moving back and forth of the individual components of the apparatus, in particular according to FIG. 2, has the effect that individual regions of the reinforcement 11 are alternately subjected to tensile loading or compressive loading, that is to say are compressed. It is also conceivable to perform the periodically successive movements of individual components of the apparatus such that the tensile loading that is exerted on the reinforcement 11 as it passes through the apparatus is entirely or partially reduced periodically from region to region. The tensile loads that are exerted on the reinforcement 11 during the production of the plastic profile 10, changing periodically from region to region, cause a snake-like weaving of the reinforcement 11 through the individual components of the apparatus, whereby the constriction or transverse contraction exerted on the reinforcement during the production of the plastic profile 10 is eliminated, or at least reduced, and as a result the form of the reinforcement 11 does not change during the production of the plastic profile 10 and the position of the reinforcement 11 in the plastic 12 remains unchanged during the production of the plastic profile 10.

[0053] A method that differs from this is conceivable, one in which only the pulling device 24 and at least one of the positioning means 15 to 18 are moved periodically back and forth with respect to the direction of production 13. As a result, a periodic portion-by-portion reduction or elimination of the tensile forces exerted on the reinforcement 11 takes place during the production of the plastic profile 10, also periodically allowing spaced-apart compressions to occur in the reinforcement 11. It is also prevented in this way that the reinforcement 11 contracts or is displaced in an undesirable way during the bundling and compression, that is to say upstream of the impregnating device 25 and the mold 23.

[0054] FIGS. 3 and 4 show a further exemplary embodiment of the invention described above. This exemplary embodiment may also constitute an independent invention.

[0055] In FIGS. 3 and 4, only part of an apparatus for producing the plastic profile provided with the reinforcement 11 is schematically represented. The part concerned here is a mold 32, which can be changed in its form such that plastic profiles of any desired shapes can be produced with it, to be precise not only the straight plastic profile 10 that is shown in FIG. 4 but also a curved plastic profile 33, which may be both reinforced and unreinforced. Like the plastic 12 of the plastic profile 10, the plastic 12 for the plastic profile 33 may be a thermoset or a thermoplastic.

[0056] The mold 32 is formed by multiple mold portions 34 following one another at a distance in the direction of production 13. In the exemplary embodiment shown, the mold 32 consists of four identical mold portions 34, which enclose in one piece the entire circumference of the plastic profile 10, 33 in the manner of a ring. The mold 32 may, however, also have a greater or smaller number of mold portions 34, which may possibly also be differently formed. Each mold portion 34, which in the exemplary embodiment shown is formed in the manner of a plate, is provided with a central molding passage 35. In the present case, all the molding passages 35 are identically formed. However, it is also conceivable that the molding passages 35 of at least some mold portions 34 are differently formed.

[0057] The molding passage 35 in each mold portion 34 is provided with a profile or shape that changes in the direction of production 13. In the exemplary embodiment of FIGS. 3 and 4, the narrowest point of each molding passage 35 is in the center of the plate-like mold portion 34. From here, the molding passage 35 widens toward the opposing outer surfaces of the respective mold portion 34, so that the contour of each molding passage 35 is uniformly convex. In FIGS. 3 and 4, the cross section of each molding passage 35 is of an arcuate form, to be precise an approximately semicircular form. However, there may also be other cross sections, for example triangular cross sections, elliptical cross sections or the like. At least at the narrowest point in the center of the mold portion 34 concerned, the molding passage 35 corresponds to the cross section of the plastic profile 10 to be produced.

[0058] The fact that the size of each molding passage 35 changes in the longitudinal direction 36 of the respective molding passage 35 means that the circumferential surface of each molding passage 35 is convex. Only in a plane in which the narrowest point of the respective molding passage 35 lies, in the exemplary embodiment shown the center of the respective mold portion 34, is there contact of the molding passage 35 with the outer surface of the plastic profile 10 to be produced. This makes it possible to position the mold portions 34 obliquely in such a way that the longitudinal direction 36 of the molding passage 35 of each mold portion 34 runs in different directions. This allows the production not only of straight plastic profiles 10 but also of a curved plastic profile 33 (FIG. 3). By obliquely positioning the mold portions 34 appropriately, a plastic profile with any desired shape can be produced. The plastic profile may be both two-dimensionally and three-dimensionally curved. In the exemplary embodiment of FIG. 4, all the mold portions 34 of the mold 32 run parallel to one another at a small distance, whereby the longitudinal directions 36 of all the molding passages 35 lie on a common straight line, to be specific the center line of the straight plastic profile 10 to be produced. If, on the other hand, the mold portions 34 are tilted according to the representation in FIG. 3, to be precise preferably to the same extent and in the same direction, the curved plastic profile 33 that is shown in FIG. 3 is produced. Then, the longitudinal directions 36 of the molding passages 35 of the mold portions 34 run tangentially with respect to the longitudinal center axis 37 of the curved plastic profile 33.

[0059] With preference, the mold portions 34 are formed from different materials, in order to reduce the friction on the lateral surface or the matrix of the plastic profile 10, 33 to be produced. For example, the first mold portion 34 in the direction of production 13 could be formed from steel, preferably high-grade steel. The then-following mold portion 34 could be formed from copper. The other mold portions 34 may be formed from thermoplastic material, for example polyoxymethylene, or aluminum.

[0060] It is also conceivable to cool all or only selected mold portions 34, in particular the mold portions 34 lying downstream in the direction of production 13, and/or to heat at least the first mold portions 34.

[0061] The method for producing plastic profiles 10, 33 having any desired shapes proceeds as follows with the mold 32 described above:

[0062] Depending on the desired form of the plastic profile 10, 33 to be produced, the mold portions 34 are aligned in relation to one another and fixed. For the production of the straight plastic profile 10, all the mold portions 34 are arranged in relation to one another such that they run parallel to one another, to be precise preferably at equal distances. The longitudinal center axes or longitudinal directions 36 of the molding passages 35 of all the mold portions 34 then lie on a common line, which corresponds to the straight longitudinal center axis 37 of the non-curved plastic profile 10 (FIG. 4).

[0063] If, on the other hand, the curved plastic profile 33 is to be produced, preferably all the mold portions 34 are tilted uniformly and in the same direction in relation to one another, to be precise such that the center planes of all the mold portions 34 converge at a common point. In this case, the longitudinal center axes 36 of the molding passages 35 of all the mold portions 34 lie tangentially on the arcuate longitudinal center axis 37 of the plastic profile 33. If the mold portions 34 are tilted multi-axially, three-dimensionally curved plastic profiles can be produced.

[0064] It is conceivable that at least one mold portion 34, the first with respect to the direction of production 13, is heated, while at least the last mold portion 34 serves for cooling the plastic profile 10 or 33 to be produced. The mold portions 34 to be cooled may be formed from a material having a relatively smooth and slidable surface, for example an appropriate plastic, but also aluminum, bronze or copper. By contrast, the respectively heated mold portion is formed from a heat-resistant material, for example steel, in particular a chrome-like steel, but possibly also aluminum, copper or bronze.

LIST OF DESIGNATIONS

[0065] 10 plastic profile [0066] 11 reinforcement [0067] 12 plastic [0068] 13 direction of production [0069] 14 positioning device [0070] 15 positioning means [0071] 16 positioning means [0072] 17 positioning means [0073] 18 positioning means [0074] 19 heating device [0075] 20 cooled inlet [0076] 21 gel zone region [0077] 22 final reaction region [0078] 23 mold [0079] 24 pulling device [0080] 25 impregnating device [0081] 26 discharge device [0082] 27 discharge device [0083] 28 passage [0084] 29 passage [0085] 30 passage [0086] 31 passage [0087] 32 mold [0088] 33 plastic profile [0089] 34 mold portion [0090] 35 molding passage [0091] 36 longitudinal direction [0092] 37 longitudinal center axis