Drawing device and method for removing a profile made of fiber-reinforced plastic from a tool

Abstract

Pulling device for removing a profile (12) made of fiber-reinforced plastic from a pultrusion tool, comprising a resin injection, forming and / or curing tool (14), with at least one gripper (16) having a surface (18) facing the profile (12) which has a contact section (20) for contact with the profile (12), characterized in that a suction area (24) is provided on the surface (18) facing the profile (12), which delimits a vacuum space (26) between itself and the profile (12), in which a suction device (28) terminates to generate a vacuum in the vacuum space (26).

Description

[0001] The invention relates to a drawing device for removing a profile made of fiber-reinforced plastic from a pultrusion tool, comprising a resin injection, forming, and / or curing tool, with at least one gripper having a surface facing the profile that has a contact section for bearing against the profile. The invention further relates to a method for removing a profile made of fiber-reinforced plastic from a pultrusion tool, comprising a resin injection, forming, and / or curing tool, by means of the aforementioned drawing device.

[0002] Fiber-reinforced plastic profiles are typically manufactured using the pultrusion process. Reinforcing fibers in the form of fiber rovings are fed into an impregnation unit, such as a resin bath or resin injection tool. During the process, the fibers pass through several pre-forming stations, which shape them into the desired profile form. It is also common to integrate mats, woven fabrics, nonwovens, or other non-woven materials into the process to optimize the mechanical properties of the finished profiles. The impregnated fibers then pass through a forming or curing die, from which they are drawn at a constant speed by a subsequent drawing unit, thus ensuring continuous feed. Following the drawing unit, a cutting unit is typically provided to trim the finished profiles to the required length.

[0003] To remove the profiles, known drawing devices have several grippers, two of which form a pair, arranged on opposite sides of the profile and clamping the profile on both sides. Extrusion processes utilizing such drawing devices are described, for example, in the generic US 2002 / 0014302 A1 and in DE 10 2010 004 865 A1.

[0004] From DE 102 19 276 A1, a device for removing a molded part from a molding tool is known, wherein the device comprises a removal gripper in the form of a suction bell.

[0005] A drawing device 1 according to the prior art is in the Fig. 1 and Fig. Figure 2 illustrates this. It connects to a hardening tool 2 and has two opposing grippers 4 arranged on either side of a profile 6. The two grippers 4 clamp the profile 6 and pull it out of the hardening tool 2 in a pull-off direction A.

[0006] The problem here is that the clamping force exerted on profile 6 can cause profile 6 to buckle or bulge, especially if it is a thin-walled profile 6, as in Fig. 2b is shown. This can even lead to the destruction of the profile by buckling.

[0007] It is therefore an object of the invention to provide a drawing device or a method with which even very thin-walled profiles can be gently removed from a tool.

[0008] According to a first aspect of the invention, a pulling device of the type mentioned above has a suction area on the surface facing the profile, which defines a vacuum space between itself and the profile. A suction device terminates in this vacuum space to generate a vacuum. The vacuum space is partially evacuated by means of the suction device to create the desired vacuum. Thus, according to the invention, in addition to or as an alternative to a clamping force exerted by the gripper(s), the profile is drawn into the gripper, thereby generating an (additional) frictional force between the gripper and the profile. This frictional force is sufficient for reliable transport of the profile without requiring strong clamping.Furthermore, the profile surface deforms not at all, or significantly less, even when clamped, compared to conventional drawing devices, as it is held in place by the vacuum applied to the gripper. This allows even very thin-walled profiles to be conveyed gently, and rejects can be largely avoided, which in turn has a positive impact on the production costs of the profiles.

[0009] A structurally simple design is achieved by preferably framing the intake area with the contact section and / or by defining a flat recess within the intake area. This recess then forms, in particular, the vacuum chamber.

[0010] To ensure a constant negative pressure, the intake area is preferably surrounded by a circumferential seal.

[0011] According to a preferred embodiment, the suction area is arranged approximately centrally in the surface facing the profile. This reliably prevents buckling of the profile surface in thin-walled profiles, a phenomenon known to occur with profiles fixed solely by clamping, since the central area of ​​the profile surface is held against the gripper by the negative pressure. In particular, the profiles only fail at significantly higher clamping forces. Of course, other configurations are also conceivable.

[0012] Preferably, the at least one gripper is designed to be movable in order to pull the profile out of the resin injection, forming and / or curing tool in a pull-off direction. The pull-off direction typically corresponds to the longitudinal axis of the profile.

[0013] In a further development of the invention, at least two grippers are provided, which facilitates the transport of the profile.

[0014] The two grippers can form a pair with opposing contact sections that grip opposite sides of the profile. In such a gripper pair, in addition to the vacuum, a clamping force can be exerted on the profile, resulting in a particularly secure hold. The suction of both surfaces of the profile to one gripper of the pair provides additional stabilization and better supports the profile's lateral webs.

[0015] Alternatively or additionally, it is conceivable that the grippers alternately transport at least one profile. Such an alternating principle, according to which the two grippers operate, ensures a continuous supply of the profile(s).

[0016] In particular, two pairs of grippers can also be provided, so that the currently active pair exerts a clamping force combined with a suction force generated by the negative pressure on the profile, pulling it a short distance out of the tool, whereupon the second pair of grippers takes over. This achieves a particularly reliable and continuous conveying process.

[0017] Alternatively, due to the suction effect caused by the negative pressure between the profile and the gripper, it is also possible that only one gripper at a time contacts the profile and removes it from the tool, thus saving components and optimizing the installation space.

[0018] The aforementioned task is also solved by a procedure of the type mentioned at the outset, which comprises the following steps: a) Attaching at least one gripper with a surface facing the profile and a suction area to the profile; b) Creating a negative pressure between the surface facing the profile and the profile; c) Moving the gripper in a pull-off direction away from the resin injection, shaping and / or curing tool; and d) Releasing the gripper by venting a vacuum space limited between the profile and the suction area.

[0019] The inventive method allows fiber-reinforced profiles produced by pultrusion to be reliably removed from a die without deformation of the profile surfaces caused by high clamping forces. This protects thin-walled profiles compared to known removal methods; in particular, the profiles only fail at significantly higher clamping forces. The inventive method thus avoids rejects and reduces production costs. This enables the relatively inexpensive production of high-quality fiber-reinforced plastic profiles.

[0020] Preferably, at least two grippers are arranged on opposite sides of the profile, each with opposing surfaces and contact sections that exert an additional clamping force on the profile when they are applied. This results in particularly reliable conveying. The suction of both surfaces of the profile against each gripper of the gripper pair thus formed provides additional stabilization and better supports the lateral webs of the profile.

[0021] In this advanced training system, at least two grippers are provided, which move alternately to transport at least one profile in succession. This allows for continuous conveying of the fiber-reinforced profile. While one gripper contacts and transports the profile, the other returns to its starting position. At the end of its gripping path, the second gripper takes over the pulling action without interrupting the conveying process.

[0022] Furthermore, all features, developments and advantages mentioned with reference to the drawing device according to the invention also apply to the method according to the invention and vice versa.

[0023] Further features and advantages will become apparent from the following description of a preferred embodiment with reference to the accompanying drawings. These show: - Fig. 1. A side view of a drawing device according to the prior art; - the Fig. 2a and Fig. 2b Sectional views of the drawing device along line II in Fig. 1, without or with the application of a clamping force to the profile; - Fig. 3 a side view of a drawing device according to the invention in which the method according to the invention is carried out; - the Fig. 4a and Fig. 4b Sectional views of the drawing device along line II-II in Fig. 3, without or with the application of a clamping force to the profile; and - Fig. 5 a diagram for comparing the stability of profiles that are conveyed using a drawing device according to the invention or a drawing device according to the prior art.

[0024] Fig. Figure 3 shows a drawing device 10 according to the invention, which serves to remove a profile 12 made of fiber-reinforced plastic from a pultrusion tool comprising a resin injection, forming and / or curing tool 14. The drawing device 10 has several grippers 16, here a total of four, each of which has a surface 18 facing the profile 12, which has a contact section 20 for bearing against the profile 12.

[0025] Two grippers 16 form a pair with opposing contact sections 20 that engage opposite sides 22, 23 of the profile 12. Each gripper 16 also has a suction area 24 on the surface 18 facing the profile 12, which in turn defines a vacuum chamber 26 between itself and the profile 12. The suction area 24 is located approximately centrally in the surface 18 facing the profile 12 and is framed by the contact section 20. The vacuum chamber 26 is designed as a planar recess, bounded on one side by the suction area 24 and on the other side by the profile 12.

[0026] In intake area 24, a [unclear] ends in Fig. 3. A merely indicated intake device 28, which can generate a vacuum in the vacuum chamber 26. In order to reliably maintain this vacuum, the intake area 24 or the vacuum chamber 26 is surrounded by a circumferential seal 30.

[0027] The grippers 16 are movably designed to pull the profile 12 out of the tool 14 in a pull-off direction A that runs parallel to the longitudinal axis of the profile 12. For this purpose, the first pair of grippers 16 is placed against the profile 12 with the surface 18 facing the profile 12, whereby the contact section 20 makes direct contact with the profile 12. Subsequently, a vacuum is created in the vacuum chamber 26 by partial evacuation using the suction device 28. In addition, the grippers 16 exert a clamping force on the profile 12, particularly in the area of ​​the contact sections 20.

[0028] The grippers 16 are then moved away from the tool 14 in the pull-off direction A, thereby pulling the profile 12 a short distance out of the tool 14. Finally, the grippers 16 are released from the profile 12 and moved away from it by venting the vacuum chamber 26 using the suction device 28. Before the first pair of grippers is released, the second pair of grippers 16, which are in their starting position, already grips the profile 12. The two pairs of grippers move alternately and transport the profile 12 or several pre-cut profiles successively, thus achieving continuous conveying.

[0029] As an alternative to the embodiment shown, it is also possible to provide only one gripper 16 instead of a pair of grippers, i.e., a total of two grippers 16 that move alternately, since the negative pressure generated in the vacuum chamber 26 causes the profile 12 to adhere to the respective gripper 16.

[0030] As from Fig. As can be seen in 4b, due to the negative pressure in the negative pressure chamber 26, the profile 12 is hardly or less deformed than in the prior art (see Fig. 2b) is the case. In particular, the surfaces bearing against the grippers 16 do not buckle. Therefore, the profile 12, which is conveyed by the drawing device 10 according to the invention, has increased stability, which makes it possible to exert a higher clamping force on it before failure and breakage of the profile 12 occurs.

[0031] This can Fig.Figure 5 compares a characteristic curve of the profile 12 conveyed according to the invention (curve K2) with a characteristic curve of the profile 6 conveyed according to the prior art (curve K1). The curve shows the frictional force acting between the grippers 16 and the profile 12, and between the grippers 4 and the profile 6, as a function of the clamping force exerted by the grippers 16 and 4, respectively. Due to the area drawn in by the negative pressure, the frictional force between the grippers 16 and the profile 12 is significantly higher at the same clamping force than in the prior art design.

[0032] Furthermore, the profile 6, which is conveyed according to the prior art, already fails at a clamping force F1 that is approximately 25% lower than the clamping force F2 at which the profile 12 conveyed according to the inventive method buckles.

Claims

[1] Pulling device for removing a profile (12) made of fiber-reinforced plastic from a pultrusion tool, comprising a resin injection, forming and / or curing tool (14), with at least one gripper (16) having a surface (18) facing the profile (12) which has a contact section (20) for contact with the profile (12), characterized by , that on the surface (18) facing the profile (12) there is an intake area (24) which defines a vacuum space (26) between itself and the profile (12) in which an intake device (28) terminates to generate a vacuum in the vacuum space (26). [2] Drawing device according to claim 1, characterized by , that the intake area (24) is framed by the contact section (20) and / or that the intake area (24) defines a flat recess. [3] Drawing device according to claim 1 or 2, characterized by , that the intake area (24) is surrounded by a circumferential seal (30). [4] Drawing device according to one of the preceding claims, characterized by , that the intake area (24) is located approximately in the middle of the surface (18) facing the profile (12). [5] Drawing device according to one of the preceding claims, characterized by , that at least one gripper (16) is designed to be movable in order to pull the profile (12) out of the resin injection, shaping and / or hardening tool (14) in a withdrawal direction (A). [6] Drawing device according to one of the preceding claims, characterized by , that at least two grippers (16) are provided. [7] Drawing device according to claim 6, characterized by , that the two grippers (16) form a pair with opposing contact sections (20) that attack opposite sides (22, 23) of the profile (12). [8] Drawing device according to claim 6 or 7, characterized by that the grippers (16) alternately transport at least one profile (12). [9] Method for removing a profile (12) made of fiber-reinforced plastic from a pultrusion tool comprising a resin injection, forming and / or curing tool (14), by means of a drawing device (10) according to one of the preceding claims, characterized by the following steps: a) Attaching at least one gripper (16) with a surface (18) facing the profile (12) and with a suction area (24) to the profile (12); b) Creating a negative pressure between the surface (18) facing the profile (12) and the profile (12); c) Moving the gripper (16) in a pull-off direction (A) away from the resin injection, shaping and / or curing tool (14); and d) Releasing the gripper (16) by venting a vacuum space (26) limited between the profile (12) and the suction area (24). [10] Method according to claim 9, characterized by, that at least two grippers (16) arranged on opposite sides (22, 23) of the profile (12) are provided with opposing surfaces (18) with contact sections (20) which exert an additional clamping force on the profile (12) when placed against it. [11] Method according to claim 9 or 10, characterized by , that at least two grippers (16) are provided which move alternately in order to transport at least one profile (12) one after the other.

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