Press tool, especially for fiber composite components, with ejector device

Abstract

Pressing tool, in particular for carrying out a wet pressing process for fiber composite components, with at least one ejector device (18), comprising a holding device for holding a component (12) located in the press tool between two tool halves (10, 22), in particular a fiber composite component, and a release mechanism that at least supports the demolding of the component (12), wherein the holding device and the release mechanism are arranged in an outer area (16) of the component (12) outside a machining area (14), characterized in that the holding device has two opposing clamping elements (34; 38) which are each movable in a direction corresponding to an opening or closing direction of the pressing tool, wherein a lower clamping element (34; 38) is mounted in a lower tool half (10) and an upper clamping element (34; 38) is mounted in an upper tool half (22), and that the holding device is arranged such that it holds the component (12) when the press tool is opened, while the component (12) is demolded from the tool halves (10, 22) by means of the release mechanism.

Description

[0001] The invention relates to a press tool with at least one ejector device.

[0002] In vehicle manufacturing, components made of carbon fiber reinforced plastic (CFRP) are increasingly used because fiber composite components offer high strength-to-weight ratio and stiffness. Heated, two-part molds are used in the wet pressing process for manufacturing and processing fiber composite components. The components are pressed with a resin-hardener mixture. Hydraulically actuated quill ejectors are used to demold a cured component. These ejectors must be installed within the mold area containing the component. To prevent contamination of the sliding surfaces between the quills and the surrounding guide bushings, the ejectors require extremely high precision in manufacturing, resulting in high production costs. Typical quill ejectors for the series production of fiber composite components in vehicle manufacturing are ground down to a depth of 5 micrometers to minimize the penetration of liquid resin.Nevertheless, production disruptions due to stuck ejectors and wear occur repeatedly. Replacing the ejectors requires the tool to be cooled down and then completely disassembled, meaning the maintenance effort for the tools is very high and impacts the availability of the press tool.

[0003] US 2007 / 0284780 A1 describes a known press tool comprising a lower tool half, an upper tool half, a holder, and an ejector device in the form of a lifting mechanism. The lifting mechanism is arranged on the holder, which in turn is mounted on an outer circumference of the lower tool half above a cushion spring. The lifting mechanism has a lifting block that is designed as a pressing surface corresponding to the shape of the upper tool half. The lifting block is positioned to absorb the force of a return spring supported on the holder. Press pins are attached to a lower section of the upper tool half, which press the lifting mechanism and the holder downwards when the upper tool half moves downwards to form a material sheet inserted between the tool halves. The lifting block is pressed down so that it is aligned with a pressing surface of the lower tool half.After the pressing process, the press tool is opened by moving the upper half of the tool upwards. This allows the lifting block, driven by the force of the return spring, to also move upwards and lift the plate resting on its edge. This separates the formed plate from the pressing surface of the stationary lower half of the tool. The plate is lifted sufficiently so that a finger can pick it up and advance it to the next process step.

[0004] German patent DE 101 53 035 A1 discloses a clamping frame for holding three-dimensionally deformable mats, in particular glass fiber reinforced mats, in order to insert the mats into a forming tool without creases. The forming tool is a press consisting of a movable upper tool and a stationary lower tool. The clamping frame consists of strips arranged laterally next to the tool, made of a magnetizable, elastic material. The clamping frame is closed by the upper strips moving downwards towards the lower strips. Separate lifting cylinders are used for this purpose.

[0005] From EP 2 586 593 A1 is a detachable snap connection of two mounting parts with a snap bolt having an extension in one mounting part and an elastic snap receptacle in the other mounting part for mounting in carriers made of porous plastic.

[0006] The object of the invention is to create a cost-effective, robust and durable ejector device for a press tool.

[0007] This problem is solved by a pressing tool with an ejector device according to claim 1. Advantageous and appropriate embodiments of the pressing tool according to the invention are specified in the dependent claims.

[0008] The press tool according to the invention, which is particularly intended for carrying out a wet pressing process, has at least one ejector device. The ejector device comprises a holding device for holding a component located in the press tool between two tool halves, in particular a fiber composite component, and a release mechanism that at least assists in demolding the component. According to the invention, the holding device and the release mechanism are arranged in an outer area of ​​the component outside of a machining area.

[0009] The invention is based on the finding that the susceptibility of an ejector device used in a press tool for a wet pressing process to wear and damage, particularly caused by the sticking of the moving components of the ejector device, can be significantly reduced if the ejector device is arranged outside the machining area, especially outside the resin-coating area of ​​the tool. This specific arrangement of the ejector device outside the machining area minimizes the risk of damage to and contamination of the section of the component being machined in the tool. The invention describes a basic design of the ejector device that enables such an arrangement.

[0010] The invention has the general advantage that the expensive and maintenance-intensive quill ejectors used until now can be dispensed with. Furthermore, the invention increases both the availability of the press tool and production reliability.

[0011] When the press tool is opened, the holding device of the ejector acts like a mechanical hand, holding the component in place while the component is demolded from the tool halves using the release mechanism.

[0012] With a special design of the ejector device according to the invention, the demolding of the held component can be largely automated. According to this design, the release mechanism has a mechanism that is activated by the separation of the mold halves. The key advantage of this design is that the release mechanism does not require its own drive to actively push the component away from the mold halves. Only the holding device needs to actively hold the component, which is significantly easier, more cost-effective, and requires less maintenance compared to an active release mechanism.

[0013] When the press tool halves are opened in the previously described setup, it should be ensured that the held component can move along with it (either towards one or the other tool half) so that it can automatically release from the tool halves. To accomplish this simply, the invention provides a two-part holding device with two opposing clamping elements, each movable in a direction corresponding to the opening or closing direction of the press tool.

[0014] To avoid a complex attachment for the holding device on the press tool, according to the invention a lower clamping element is mounted in a lower tool half and an upper clamping element is mounted in an upper tool half.

[0015] A particularly preferred design of the ejector device includes means for limiting the stroke of the lower clamping element relative to the lower tool half in the direction of the upper tool half, and / or means for limiting the stroke of the upper clamping element relative to the upper tool half in the direction of the lower tool half. When the press tool opens, a first tool half (for example, the upper one) then takes both clamping elements with the component held between them, so that the component detaches from the second (lower) tool half. After the maximum stroke of the clamping element mounted in the second (lower) tool half has been reached, further opening of the press tool prevents the clamping elements and the component from moving with the first (upper) tool half (relative to the lower one), so that the component then automatically detaches from the first (upper) tool half as well.A limiter that interacts with a stop can be used to limit the stroke, for example in the form of a retaining screw with a widened head that rests against a holding surface.

[0016] With regard to a defined, reproducible demolding process, this design also makes it possible to specify from which mold half the component is demolded first. For this purpose, at least one spring element is provided, which biases one of the clamping elements, preferably the upper one, against its stroke direction. The resistance of the spring element ensures that the clamping elements, with the component held between them, move first with one, preferably upper, mold half, so that the component is demolded first from the other, preferably lower, mold half. Furthermore, the spring element has the advantage that, after the component has been completely demolded from both mold halves, when the spring element is tensioned, the (preferably upper) clamping element is automatically pulled away from the component by the spring force when the clamp is released.Even if the lower clamping element is not actuated by a spring element, it will still move away from the component simply due to its own weight and gravity. However, the lower clamping element can also be equipped with a spring element to assist this movement. In this case, it is advantageous to design this additional spring element to be weaker than the spring element acting on the upper clamping element.

[0017] According to a preferred arrangement of the clamping elements, these are arranged on opposite end faces of quills which are received in guide bushings.

[0018] To hold the component in place before and during the demolding process, (electro)magnetic forces can be used, which can be easily switched on and off. The holding device can accordingly have at least one electromagnet or permanent magnet that interacts with an opposing electromagnet or a soft magnetic component to generate the clamping force required for holding.

[0019] The simplest solution is to use at least one electromagnet or permanent magnet simultaneously as a clamping element.

[0020] To ensure that the component is held securely in the holding device, at least one of the clamping elements can be formed by a clamping jaw.

[0021] The electromagnet or permanent magnet and clamping jaw can be arranged side by side on a distribution plate to achieve a compact design.

[0022] A holding device that operates entirely without electromagnets consists of two opposing elements that can form a releasable snap connection. In this case, the component is clamped purely mechanically between the snap elements. After the component is demolded from the mold halves, the snap connection can be released, allowing the component to be removed from the mold.

[0023] Further features and advantages of the invention will become apparent from the following description and from the accompanying drawings, to which reference is made. The drawings schematically show: - Fig. 1 a top view of one half of a press tool with a component inserted therein; - Fig. 2 a lateral sectional view of a part of a press tool according to the invention with an ejector device according to a first embodiment in the closed state; - Fig. 3 the pressing tool Fig. 2 in a first step of component demolding; - Fig. 4 the pressing tool Fig. 2 in a second step of component demolding; - Fig. 5 the pressing tool Fig. 2 in a third step of component demolding; - Fig. 6 a second embodiment of the ejector device in the third step of component demolding; - Fig. 7 a third embodiment of the ejector device in the third step of component demolding; and - Fig. 8 a fourth embodiment of the ejector device in the third step of component demolding.

[0024] In Fig. Figure 1 shows an example of the lower half 10 of a press tool designed for carrying out a wet pressing process to machine or manufacture a fiber composite component 12. The contact surface of the component 12 in the tool half 10 can be divided into a resin-coated area 14 and an area 16 that is not resin-coated. The resin-free area 16 of the component 12 is an external area where, generally, no machining of the component 12 takes place.

[0025] Fig. Figure 2 shows one of several ejector devices 18 with which the component 12 is demolded after completion of the pressing process, i.e., removed from the press tool. The ejector devices 18 are preferably arranged at the corners of the component 12 in the outer area 16. Fig. In the tool shown in Figure 1, four of these ejector devices 18 are provided at the positions designated 20.

[0026] Each ejector device 18 is designed in two parts, with an upper part being received in the upper tool half 22 and the lower part in the lower tool half 10. Both parts of the ejector device 18 comprise a quill 24 which is slidably mounted in a guide bushing 26 in a direction corresponding to the opening or closing direction of the press tool.

[0027] A retaining screw 28 with a head wider than the inner diameter of the guide bushing 26 is screwed into the outer end face of the quill 24. In the case of the upper retaining screw 28, a spring element 32 in the form of a helical spring is arranged between its head or a retaining plate mounted thereon and a retaining surface 30 of the upper tool half 22, which is formed by the upper outer surface or, as in this case, by the bottom surface of a recess in the upper tool half 22. In the illustrated embodiment, no spring element is provided for the lower retaining screw 28.

[0028] The retaining screws 28, which serve as limiters, and the retaining surfaces 30, which serve as stops, as well as the spring element 32 (if applicable), are coordinated with each other so that the quills 24 – starting from the one in Fig. 2 shown condition - when opening the press tool relative to their tool halves 22 and 10, they can each perform a stroke of approximately 30 to 50 mm.

[0029] Electromagnets 34 in the form of compact pot magnets with a locking plate are arranged on the opposing inner end faces (relative to the pressing tool) of the quills 24. The electromagnets 34 can be energized so that they attract each other.

[0030] The following will be based on the Fig. 2, Fig. 3, Fig. 4 to Fig. 5 the basic functioning of an ejector device 18 is explained as representative of all ejector devices 18 provided for.

[0031] Fig. Figure 2 shows the press tool in the closed state. The component 12 is firmly clamped in its outer area 16 between the energized electromagnets 34, which also serve as clamping elements. The spring element 32 is either completely relaxed or only slightly compressed.

[0032] When the two tool halves 22, 10 move away from each other during the opening of the press tool, the spring element 32 ensures that the lower quill 24 is raised relative to the lower tool half 10, while the upper quill 24 does not move downwards at all or only very slightly relative to the upper tool half 22. This results in, as in Fig. Figure 3 shows the component 12 demolded from the lower tool half 10.

[0033] When the pressing tool is opened further, according to Fig. 4. The lower retaining screw 28 comes into contact with the lower retaining surface 30, so that the lower quill 24 can no longer make any further stroke relative to the lower tool half 10. The upper quill 24, which is still firmly coupled to the lower quill 24 thanks to the electromagnets 24, is thereby pressed downwards against the force of the spring element 32 relative to the upper tool half 22. Thus, the component 12 is also demolded from the upper tool half and is ultimately only held by the holding device of the ejector assembly 18.

[0034] If the electromagnets 34 are now switched off, i.e., no longer attracting each other, then according to Fig. 5. The upper quill 24 is driven upwards by the spring force of the spring element 32. The lower quill 24 falls downwards due to its own weight. This movement can be assisted by an additional spring element located between the head of the lower retaining screw 28 or a retaining plate mounted thereon and the lower retaining surface 30. However, this additional spring element must be designed to be weaker than the spring element 32 if, when opening the press tool – as described above – the demolding of the component 12 from the lower tool half 10 is to occur first.

[0035] After both quills 24 with the clamping elements have automatically moved away from component 12, component 12 is free and can be removed from the pressing tool.

[0036] The Fig. 6, Fig. 7 to Fig. Figure 8 shows further exemplary embodiments of the ejector device based on the previously described design. The following discussion focuses only on the essential differences from the embodiment shown in Figure 8. Fig. 2, Fig. 3, Fig. 4 to Fig. 5 received.

[0037] At the in Fig. In the embodiment shown in Figure 6, a distribution plate 36 is mounted on the inner end face of each of the quills 24, and the electromagnets 34 are attached to this distribution plate. In addition to the electromagnets 34, clamping jaws 38 are also attached to the distribution plate 36. The electromagnets 34 attract each other when a corresponding current is applied, but the component 12 is not clamped between the electromagnets 34, but rather between the clamping jaws 38, which are provided with a special surface.

[0038] The embodiment of the Fig. 7 also has a clamping jaw 38, but only on the distributor plate 36 of the upper quill 24. The distributor plate 36 is made of iron or another soft magnetic material and does not carry an electromagnet 34. The lower quill 24, instead, carries only an electromagnet 34 on its inner end face. The distributor plate 36, the clamping jaw 38, and the electromagnet 34 are matched in shape and arrangement such that the component 12 is clamped between the clamping jaw 38 and the electromagnet 34 when the pressing tool is closed.

[0039] The in Fig.The embodiment shown in Figure 8 represents a modification that does not require an electromagnet. Opposing locking elements 40 have a complementary pin / socket geometry, which, upon initial opening of the pressing tool, ensures that the two quills 24 remain firmly coupled to one another and continue to securely clamp the component 12. Only when the pressing tool is opened to the point where both retaining screws 28 have reached their stops does the further separation of the two tool halves 22, 10 release the mechanical locking connection of the locking elements 40.

[0040] In another embodiment of the press tool, not shown, the mechanical locking elements are replaced by a pair of permanent magnets with a soft magnetic counter plate. The function of these permanent magnets is then exactly the same as that of the mechanical locking elements.

[0041] It is of course possible to combine various features of the exemplary embodiments described in a suitable manner. Reference symbol list 10 lower tool half 12 components 14 Resin application area 16 non-resin-treated area 18 Ejector device 20 Position of the ejector device 22 upper tool half 24 quills 26 Guide bushing 28 retaining screw 30 holding area 32 spring element 34 Electromagnet 36 distribution plate 38 clamping jaw 40 locking elements

Claims

[1] Pressing tool, in particular for carrying out a wet pressing process for fiber composite components, with at least one ejector device (18), comprising a holding device for holding a component (12) located in the press tool between two tool halves (10, 22), in particular a fiber composite component, and a release mechanism that at least supports the demolding of the component (12), wherein the holding device and the release mechanism are arranged in an outer area (16) of the component (12) outside a machining area (14), characterized by, that the holding device has two opposing clamping elements (34; 38) which are each movable in a direction corresponding to an opening or closing direction of the pressing tool, wherein a lower clamping element (34; 38) is mounted in a lower tool half (10) and an upper clamping element (34; 38) is mounted in an upper tool half (22), and that the holding device is arranged such that it holds the component (12) when the press tool is opened, while the component (12) is demolded from the tool halves (10, 22) by means of the release mechanism. [2] Pressing tool according to claim 1, characterized by , that the release mechanism has a mechanism which is activated by moving the tool halves (10, 22) apart. [3] Pressing tool according to claim 1 or 2, characterized byMeans (28, 30) for limiting a stroke of the lower clamping element (34; 38) relative to the lower tool half (10) in the direction of the upper tool half (22) and / or by means (28, 30) for limiting a stroke of the upper clamping element (34; 38) relative to the upper tool half (22) in the direction of the lower tool half (10). [4] Pressing tool according to claim 3, characterized by , that at least one spring element (32) is provided which biases one of the clamping elements (34; 38), preferably the upper clamping element, against the stroke direction of the clamping element (34; 38). [5] Pressing tool according to one of the preceding claims, characterized by , that the clamping elements (34; 38) are arranged on opposite end faces of quills (24) which are received in guide bushings (26). [6] Pressing tool according to one of the preceding claims, characterized by, that the holding device has at least one electromagnet (34) or permanent magnet which interacts with an opposing electromagnet (34) or a soft magnetic part (36). [7] Pressing tool according to one of the preceding claims, characterized by , that at least one of the clamping elements is formed by an electromagnet (34) or permanent magnet. [8] Pressing tool according to any one of claims 1 to 6, characterized by , that at least one of the clamping elements is formed by a clamping jaw (38). [9] Pressing tool according to claim 7 or 8, characterized by , that at least one electromagnet (34) or permanent magnet and one clamping jaw (38) are arranged next to each other on a distribution plate (36). [10] Pressing tool according to any one of the preceding claims, characterized by , that the holding device has two opposing elements (40) which can form a releasable snap connection.

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