PULTRUSION METHOD AND PULTRUSION DEVICE FOR THE PRODUCTION OF CURVED COMPOSITE PROFILES

Description

[0001] The invention relates to a pultrusion process for producing curved composite profiles, in which reinforcing materials are wetted with a polymer matrix material and the wetted reinforcing materials are drawn through a forming tool by means of a pultrusion device. Furthermore, the invention relates to a pultrusion device comprising a forming tool and a pultrusion device.

[0002] The conventional pultrusion process is based on drawing reinforcing materials, such as fibers or other textile semi-finished products, from spools through a resin bath and a mold. In the mold, the resin-wetted reinforcing materials are formed into a composite profile and geometrically defined. Furthermore, the wetted reinforcing materials are at least partially cured by applying energy, for example, through electrical heating or UV radiation.

[0003] Conventionally, this process is driven by so-called pullers, which engage the finished and cured composite profile and pull all starting materials through the individual process stages, allowing straight-shaped composite profiles to be produced continuously.

[0004] The production of curved composite profiles requires additional design and process engineering measures. For example, DE 10 2016 015 421 A1 describes a pultrusion process in which the forming tool is moved back and forth along a curved trajectory relative to a plastic profile that is at least temporarily stationary. This so-called radius pultrusion process can be used, for example, to produce circular arc segments, which can then be joined together in subsequent joining steps to form a circular composite profile.

[0005] However, due to the discontinuous process and the additional work steps required, the radius pultrusion process is very time-consuming and costly compared to the conventional pultrusion process. Furthermore, the smallest achievable radius of the circular arc is limited by the size and arrangement of the forming tool and pullers. Likewise, the maximum achievable length of the circular arc or forming length is limited, as collision between the plastic profile and the forming tool must be avoided to ensure trouble-free process execution.

[0006] For example, US 3 873 399 A discloses a device and a method for producing elongated plastic articles provided with reinforcement.

[0007] US 4 469 541 A relates to a method for forming reinforced plastic composite articles.

[0008] US 9 044 998 B2 discloses a frame part or a frame made of a composite material.

[0009] The object of the invention is therefore to propose a pultrusion process and a pultrusion device with which curved composite profiles can be produced variably, in a time- and cost-saving manner. According to the invention, this object is achieved by the features stated in claims 1 and 7. Advantageous variants arise from the features stated in the subclaims.

[0010] In the pultrusion process according to the invention for producing curved composite profiles, reinforcing materials are wetted with a polymer matrix material, and the wetted reinforcing materials are drawn through a forming tool by means of a pultrusion device. The wetted reinforcing materials are formed into a composite profile in the forming tool and cured to a dimensionally stable state. After exiting the forming tool, the dimensionally stable, cured composite profile is continuously wound onto a cylindrical unit as part of the pultrusion device.

[0011] The reinforcing materials can be formed, for example, with fibers or textile semi-finished products. The composite profile can be a fiber composite profile. The polymer matrix material can be formed with resin, for example, with an epoxy resin. The wetted reinforcing materials can also be fully cured in the mold. The curvature of the composite profile is predetermined in the mold. In this case, the wetted reinforcing materials are formed in the mold into a dimensionally stable and curved composite profile. In addition, a predetermined, final curvature of the composite profile can also be formed during winding onto the cylindrical unit.

[0012] Here and in the following, continuous winding is understood to mean a process step in which at least one turn of the dimensionally stable, cured composite profile can be wound without the composite profile coming to a standstill. For example, the composite profile can be wound onto the cylindrical unit in multiple turns. Depending on the geometry and / or arrangement of the forming tool and the cylindrical unit, different paths or trajectories result during winding. The composite profile is wound onto the cylindrical unit in a spiral or helix shape. A helix refers to a helical curve or trajectory along which the composite profile winds around the cylindrical unit.

[0013] The proposed process enables the continuous, cost-effective and time-saving production of curved composite profiles with virtually any desired number of coils and forming length in large quantities. The radius or radius of curvature of the composite profile can be specified by a predetermined curvature of the path or trajectory of the composite profile in the forming tool or in a forming area of ​​the forming tool and is not limited by the size or dimensions of the forming tool itself. Thus, even curved composite profiles with small radii can be produced. Since the curved composite profile can be wound onto the cylindrical unit in a solid, cured, and dimensionally stable state, curved hollow profiles or solid profiles can also be produced continuously without being deformed by the winding process.Coiling or reeling the composite profile also enables uncomplicated drawing or pulling of the reinforcement materials, thus simplifying the control of the pultrusion process. Coiling or reeling can also achieve a supporting effect for the curved profile structures. Furthermore, the pull-off forces and clamping forces can be distributed more evenly across the composite profile and also reduced. Elastic deformations that have formed in the profile due to the pull-off can be reduced again after cutting. Continuous winding of the composite profile can be achieved by continuous rotation of the cylindrical unit about its central longitudinal axis. Preferably, the composite profile or at least an initial section of the composite profile is fixed or held to the cylindrical unit and then wound up by the rotation, like a reel.

[0014] After or during winding, segments of the composite profile, for example, circular segments with at least one turn, can be severed using a cutting or sawing tool. Circular segments are preferably severed using a V-cut, i.e., the cutting edge has a V-shaped tip. A V-cut enables more favorable load distribution than a straight cut. By severing or dividing the wound composite profile, almost completely closed circular rings can be produced, with only a small opening at the cutting point. Alternatively, circular segments can also be severed using an oblique or diagonal cut.

[0015] At least temporarily, the composite profile can be pulled or pushed in a direction parallel to the central longitudinal axis of the cylindrical unit to ensure continuous winding of the composite profile in the form of a helix by offsetting the windings in the pulling or pushing direction. A direction parallel to the central longitudinal axis of the cylindrical unit is also referred to below as the cylinder axis direction. The translational pulling or pushing of the composite profile in the cylinder axis direction can occur periodically after each winding or continuously. This allows space to be created on or at the cylindrical unit for the subsequent winding or for the next winding.

[0016] Alternatively or additionally, at least the forming area of ​​the forming tool can be slightly inclined or curved in the direction of the cylinder axis to accommodate any offset of the windings during winding and to prevent stresses in the wound composite profile. After cutting open the wound composite profile or separating annular segments, an offset may remain at the ends of the separated rings. This offset can be compensated for by applying additional mechanical stress, for example, by bending the ring end pieces.

[0017] Additionally or alternatively, before being wound onto the cylindrical unit, the curved composite profile can be bent by at least one width of the cross-section of the composite profile in a direction parallel to the central longitudinal axis of the cylindrical unit, in order to ensure continuous winding of the composite profile in the shape of a helix by offsetting the windings in the bending direction. The composite profile can be wound under slight tension. As a result of the bending, the composite profile is no longer arranged two-dimensionally in a plane, but can wind around the cylindrical unit in a helical or helix shape. After the resulting screw or helix is ​​cut open, or after annular segments are separated, a separated, almost closed circular ring can relax on its own and join together to form a ring without internal stress.The pultrusion process can be used, for example, to manufacture bicycle rims. It can be advantageous to pull the reinforcing materials together with an insert strip through the mold and wind them onto the cylindrical unit in the form of the composite profile. Preferably, the insert strip is bonded to the reinforcing materials in the mold using the polymer matrix material. This can also increase the stability of the rim. For example, the insert strip can enable emergency running properties in the event of a rim breakage. The insert strip preferably has hollow cylindrical protrusions that can define a desired perforation in the composite profile for the position of the spokes. The hollow cylindrical protrusions displace the reinforcing materials along the composite profile, thus replacing the otherwise necessary cuts or drillings in the composite profile.In particular, the fiber density and stiffness are increased at the hollow cylindrical elevations or spoke positions. A form-fitting or material-fit connection between the insert strip and the reinforcement materials can support and better distribute the load, particularly at the opening or joint. The insert strip can, for example, be formed as a metal strip with at least one metallic material.

[0018] The pultrusion process can be carried out using the pultrusion device described below: The pultrusion device according to the invention for producing curved composite profiles comprises a forming tool and a pultrusion device with a cylindrical unit. The forming tool is configured to form reinforcing materials wetted with a polymer matrix material into a composite profile with a predetermined cross-sectional profile and / or radius of curvature and to cure it in a dimensionally stable manner. The pultrusion device is configured to continuously wind the reinforcing materials, formed into a composite profile and cured, onto the cylindrical unit.

[0019] The molding tool can have a heating device, for example an electric heater or an oven, for heating the reinforcing materials wetted with the polymer matrix material. Alternatively or additionally, the molding tool can also have a radiation chamber for irradiating the reinforcing materials wetted with the polymer matrix material with electromagnetic radiation, preferably in the ultraviolet wavelength range. In addition, the molding tool can have an inner contour which predetermines an outer contour of the composite profile. To form a composite profile as a hollow profile, the molding tool can also have a further inner contour which predetermines an inner contour of the composite profile. The molding tool can also have a curing unit arranged downstream of the heating device or the radiation chamber in the transport direction, in / on which the composite profile cures in a dimensionally stable manner, wherein the web orThe trajectory of the composite profile after it leaves the mold in the curing unit can be determined or specified. The transport direction, here and in the following, refers to the direction in which the reinforcement materials or the composite profile are pulled through the mold.

[0020] The pultrusion device may have a rotary drive configured to rotate the cylindrical unit around its central longitudinal axis. The outer radius of the cylindrical unit should approximately correspond to the specified radius of curvature.

[0021] At least one shaping region of the forming tool, i.e. a region of the forming tool or the curing unit arranged at the end of the forming tool in the transport direction, or a shaping region of the path or trajectory of the composite profile running in the forming tool can also be inclined or curved in a direction parallel to the central longitudinal axis of the cylindrical unit. The angle of inclination or curvature can be selected such that the desired offset of the turns during winding is taken into account. In this shaping region, the normal vector of the tangential plane of the path or trajectory of the composite profile can form an angle φ with the central longitudinal axis of the cylindrical unit that is greater than 0° and less than 90°. Alternatively, the angle φ can also be 0° or 90°.

[0022] Alternatively, the longitudinal axis of the forming tool or the path or trajectory of the composite profile running within the forming tool can also be arranged in a plane, hereinafter also referred to as the tool plane. In particular, the central longitudinal axis of the cylindrical unit can form a normal vector of the tool plane.

[0023] Preferably, the cylindrical unit is formed with a plurality of conveyor devices arranged in a circle around the central longitudinal axis of the cylindrical unit. For example, at least three conveyor devices, preferably at least six conveyor devices, can be arranged at equal angular distances from one another. The conveyor devices can be aligned parallel to the central longitudinal axis of the cylindrical unit. At least one conveyor device can be configured to move or pull the curved composite profile in a cylinder axis direction or in a direction parallel to the central longitudinal axis of the cylindrical unit.

[0024] Preferably, at least one of the conveyor devices has at least one fixing means and / or at least one drive. The at least one conveyor device can be configured to hold or fix the composite profile to the at least one conveyor device by means of the at least one fixing means. The fixing should advantageously take place at the front end of the composite profile in the pulling direction.

[0025] Furthermore, at least one of the conveying devices can be configured to displace the composite profile by means of the at least one drive in a direction parallel to the central longitudinal axis of the cylindrical unit.

[0026] For uniform winding of the composite profile, the rotational movement of the cylindrical unit and the translational movement carried out by at least one of the conveyor devices should be synchronized with each other so that the windings can be formed next to each other or at certain distances from each other on the cylindrical unit.

[0027] The pultrusion device can additionally have a rod-shaped adjusting device, e.g. a holding rod, along its central longitudinal axis. The adjusting device can be articulated to the cylindrical unit and / or the conveying devices via holding means, e.g. rods, bars or levers, wherein the radius of the cylindrical unit can be changed by pulling and / or pushing the rod-shaped adjusting device along the central longitudinal axis of the cylindrical unit and pivoting the rods, bars or levers. By changing the radius, the cylindrical unit can be brought into contact with the composite profile on its outer surface. Alternatively, the conveying devices can also be removed from the composite profile, e.g. for trouble-free separation of segments of the wound composite profile.The adjustment device also allows the outer radius of the cylindrical unit to be adjusted to a radius of curvature of the composite profile specified in the forming tool. Thus, a pultrusion device and / or cylindrical unit can also be used for forming tools and / or composite profiles with different radii of curvature.

[0028] Particularly preferably, the conveying devices are each formed with at least one circulating drag chain or one circulating conveyor belt. A drag chain or conveyor belt can be mounted on rollers or axles so as to be rotatable about a rotational axis. The rotational axis can form a right angle with the central longitudinal axis of the cylindrical unit.

[0029] The pultrusion device can also be formed with an insert belt having hollow cylindrical elevations, wherein the pultrusion device can be configured to pull the insert belt together with the reinforcing materials through the forming tool and to wind it onto the cylindrical unit.

[0030] Embodiments of the invention are illustrated in the drawings and will be described below with reference to Figures 1 to 3 explained.

[0031] Showing: Fig. 1a a longitudinal section through an example of a pultrusion device with a forming tool and a cylindrical unit, Fig. 1b a cross section through the pultrusion device along the section line AA in Figure 1a , Fig. 2a a longitudinal section through an example of a pultrusion device with an adjusting device and a cylindrical unit with a small radius, Fig. 2ba longitudinal section through a pultrusion device with an adjusting device and a cylindrical unit with a large radius, Fig. 2c a longitudinal section through another example of a pultrusion device with a cylindrical unit and a curved composite profile wound into a helix with several turns, Fig. 2d a cross section through the pultrusion device along the section line AA in Figure 2c , Fig. 3a a longitudinal section through an insert band with hollow cylindrical elevations, Fig. 3b a cross-section through the insert band along the section line AA in Figure 3a .

[0032] Figure 1ashows a longitudinal section through an example of a pultrusion device. The pultrusion device has a forming tool 1 and a pultrusion device with a cylindrical unit 3. The forming tool 1 is designed to shape reinforcing materials wetted with a polymer matrix material into a composite profile 2 with a predetermined cross-sectional profile and radius of curvature and to cure it in a dimensionally stable manner. The pultrusion device, which is formed with the cylindrical unit 3, is designed to continuously wind the reinforcing materials, shaped into a composite profile 2 and cured, onto the cylindrical unit 3. The pultrusion device can additionally have a rail system (not shown) as a transport means, with which the reinforcing materials or the composite profile 2 can be transported through the forming tool 1 and guided to the cylindrical unit 3.The polymer matrix material is a resin and the reinforcing materials are formed with fibers.

[0033] With the Figure 1a A pultrusion process for producing curved composite profiles 2 is carried out in the pultrusion device shown. In the pultrusion process, reinforcing materials are wetted with a polymer matrix material, and the wetted reinforcing materials are drawn through the forming tool 1 by means of the pultrusion device. The wetted reinforcing materials are formed into a composite profile 2 in the forming tool 1 and cured to a dimensionally stable state. After exiting the forming tool 1, the dimensionally stable, cured composite profile 2 is continuously wound onto the cylindrical unit 3, which is part of the pultrusion device.

[0034] The composite profile 2 is wound onto the cylindrical unit 3 as a solid and dimensionally stable hollow profile or cross-sectional profile with multiple windings in the form of a helix. The continuous winding of the composite profile 2 is achieved by a continuous rotation of the cylindrical unit 3 around its central longitudinal axis. For this purpose, the pultrusion device or the cylindrical unit has a rotary drive.

[0035] In Figure 1a The forming area of ​​the forming tool 1 is slightly inclined in a cylinder axis direction in order to take into account an offset of the windings during winding and to avoid causing additional stresses in the wound composite profile 2. The normal vector of the tangential plane of the trajectory of the composite profile 2 running in the forming area of ​​the forming tool 1 forms an angle φ with the central longitudinal axis of the cylindrical unit 3, which angle can be, for example, 20°.

[0036] From the schematic representation in Figure 1b It becomes clear that the composite profile 2 is wound onto the cylindrical unit 3 with a predetermined radius of curvature. The outer radius of the cylindrical unit 3 corresponds to the predetermined radius of curvature of the composite profile 2. Recurring features are provided with identical reference numerals in this figure as well as in the following figures.

[0037] With the described pultrusion device, for example, circular ring-shaped segments with one turn each can be separated, e.g. by means of a V-cut.

[0038] Figure 2ashows a longitudinal section through an example of a pultrusion device with a cylindrical unit 3 with a small radius. The cylindrical unit 3 is formed with a plurality of conveyor devices 6 arranged in a circle around the central longitudinal axis of the cylindrical unit 3. The conveyor devices 6 run parallel to the central longitudinal axis of the cylindrical unit 3. The pultrusion device also has a rod-shaped adjusting device 7 aligned along the central longitudinal axis of the cylindrical unit 3. The adjusting device 7 is articulated to the conveyor devices 6 via rods 8 as holding means 8, wherein by pulling the rod-shaped adjusting device 7 along the central longitudinal axis of the cylindrical unit 3, the radius of the cylindrical unit 3 can be reduced by moving the rods 8 around axes of rotation at their front ends.

[0039] The conveyor devices 6 are each formed by a rotating drag chain. The drag chains are mounted on rollers for rotation about a rotation axis. The rotation axes of the drag chains form a right angle with the central longitudinal axis of the cylindrical unit 3.

[0040] Figure 2b shows a longitudinal section through the pultrusion device with a cylindrical unit 3 with a large radius. The radius of the cylindrical unit 3 can be increased by pressing the rod-shaped adjusting device 7 along the central longitudinal axis of the cylindrical unit 3 and pivoting the rods 8 toward the forming tool 1.

[0041] Figure 2c shows a longitudinal section through a pultrusion device with the Figure 2b shown cylindrical unit 3 with a large radius (adjusting device 7 and holding means 8 are shown in Fig. 2cnot shown). The curved composite profile 2 is wound with several turns. In Figure 2cA conveyor device 6.1 is configured to displace the curved composite profile 2 in a direction parallel to the central longitudinal axis of the cylindrical unit 3. For this purpose, one conveyor device 6.1 has pins as gripping devices or fixing means and a drive. The composite profile 2 is fixed to the one conveyor device 6.1 using the pins or a fixing means, preferably with the front end in the pulling direction. The drive is configured to displace the composite profile 2 in a direction parallel to the central longitudinal axis of the cylindrical unit 3. This ensures the continuous winding of the composite profile 2 in the form of a helix by an offset of the windings in the pulling direction. The rotation of the cylindrical unit 3 and movement of the conveyor device 6.1 parallel to the central longitudinal axis of the cylindrical unit 3 should be synchronized to enable uniform winding.

[0042] Figure 2d shows a cross section through the pultrusion device along the section line AA in Figure 2c . It is clear that the cylindrical unit is formed with a total of six conveyor devices 6. The conveyor devices are arranged in a circle around the longitudinal axis of the cylindrical unit.

[0043] Figure 3a shows a longitudinal section through an insert band 4 with hollow cylindrical elevations 5. Figure 3b shows a cross section through the insert band 4 along the section line AA in Figure 3aIn the pultrusion process, the reinforcing materials are pulled through the forming tool 1 with the insert strip 4 as an insert and wound onto the cylindrical unit 3 in the form of the composite profile 2. The insert strip 4 is bonded to the reinforcing materials in the forming tool 1 as part of the composite profile. As shown in Figure 3b As shown, the hollow cylindrical elevations 5 displace the reinforcing materials, in particular fibers or filaments of the respective composite material along the composite profile 2. As a result, holes are formed in the composite profile 2.

Claims

1. A pultrusion method for producing curved composite profiles, in which reinforcement materials are wetted with a polymer matrix material and the wetted reinforcement materials are pulled through a forming die (1) by way of a pultrusion unit, the wetted reinforcement materials being shaped in the forming die (1) into a composite profile (2) and being cured in a dimensionally stable manner, and the composite profile (2) that has been cured in a dimensionally stable manner, after exiting the forming die (1), being continuously wound on a cylindrical unit (3) as part of the pultrusion unit, and the continuous winding of the composite profile (2) being achieved by a continuous rotation of the cylindrical unit (3) about the center longitudinal axis thereof, characterised in that the composite profile (2) is wound with a plurality of windings in a spiral-shaped manner or in the shape of a helix onto the cylindrical unit (3).

2. The pultrusion method according to claim 1, characterized in that the composite profile (2) is wound in the form of a solid and dimensionally stable hollow profile onto the cylindrical unit (3).

3. The pultrusion method according to any one of the preceding claims, characterized in that circular ring-shaped segments having at least one winding are severed from the wound composite profile (2) using a V-cut.

4. The pultrusion method according to any one of the preceding claims, characterized in that the composite profile (2) is at least intermittently pulled or pushed in a direction that is parallel to the center longitudinal axis of the cylindrical unit (3) so that continuous winding of the composite profile (2) in the form of a helix is achieved by an offset of the windings which is formed in the pulling or pushing direction.

5. The pultrusion method according to any one of the preceding claims, characterized in that the curved composite profile (2), prior to being wound on the cylindrical unit (3), is bent in a direction that is parallel to the center longitudinal axis of the cylindrical unit (3) by at least a width of the cross-section of the curved composite profile (2) so that continuous winding of the composite profile (2) in the form of a helix is achieved by an offset of the windings which is formed in the bending direction.

6. The pultrusion method according to any one of the preceding claims, characterized in that the reinforcement materials, together with a liner strip (4), are pulled through the forming die (1) and are wound on the cylindrical unit (3) in the form of the composite profile (2), the liner strip (4) being integrally joined with the reinforcement materials in the forming die (1) and / or the liner strip (4) having hollow-cylindrical elevations (5), which predefine a perforation to be achieved in the curved and cured composite profile (2).

7. A pultrusion device for producing curved composite profiles comprising a forming die (1) and a pultrusion unit which comprises a cylindrical unit (3), the forming die (1) being configured to shape reinforcement materials wetted with a polymer matrix material into a composite profile (2) having a predefined cross-sectional profile and / or radius of curvature and to cure these in a dimensionally stable manner, and the pultrusion unit being configured to continuously wind the cured reinforcement materials shaped into a composite profile (2) on the cylindrical unit (3), and the pultrusion unit comprising a rotary drive, which is configured to rotate the cylindrical unit (3) about the center longitudinal axis thereof, characterised in that at least one shaping region of the forming die (1) is inclined or curved in a direction that is parallel to the center longitudinal axis of the cylindrical unit (3) and / or the forming die (1) and the pultrusion unit are configured so that the normal vector of the tangential plane of the trajectory of the composite profile (2) which extends in the shaping region of the forming die (1) forms an angle ϕ with the center longitudinal axis of the cylindrical unit (3) which is greater than 0° and smaller than 90°, or the cylindrical unit (3) is formed with a plurality of conveying devices (6), which are arranged in a circular manner about the center longitudinal axis of the cylindrical unit (3) and extend parallel to the center longitudinal axis of the cylindrical unit (3), at least one conveying unit (6.1) of the conveying devices (6) being configured to displace or pull the curved composite profile (2) in a direction parallel to the center longitudinal axis of the cylindrical unit (3) during the winding process, and / or at least one conveying unit (6.1) of the conveying devices (6) comprises at least one fixing means and at least one drive, the at least one conveying device (6.1) being configured to fix the curved composite profile (2) at the at least one conveying device (6.1) by way of the at least one fixing means and to displace or pull it in a direction parallel to the center longitudinal axis of the cylindrical unit (3) by way of the at least one drive, or the pultrusion unit additionally comprises an adjusting device (7) that is rod-shaped along the center longitudinal axis, which is connected in an articulated manner to the conveying devices (6) by way of retaining means (8), the distance between the conveying devices (6) and the center longitudinal axis of the cylindrical unit (3), and thus the radius of the cylindrical unit (3), being varied by pulling and / or pushing the rod-shaped adjusting device (7) along the center longitudinal axis of the cylindrical unit (3).

8. The pultrusion device according to claim 7, characterized in that the outer radius of the cylindrical unit (3) corresponds to the radius of curvature of the composite profile (2) predefined in the forming die (1) or can be set to a predefinable radius.

9. The pultrusion device according to claim 7 or 8, characterized in that each of the conveying devices (6) is formed with at least one revolving drag chain or with a revolving conveyor belt.

10. The pultrusion device according to any one of claims 7 to 9, characterized in that the pultrusion unit is formed with a liner strip (4) having hollow-cylindrical elevations (5), the pultrusion unit being configured to pull the liner strip (4), together with the reinforcement materials, through the forming die (1) and wind it on the cylindrical unit (3).