Method and apparatus for heating and transporting thermoplastic fiber composite panels

Abstract

Method for transporting heated thermoplastic fiber composite panels (2) along a heating section (11) of a heating device (10) to a subsequent station (20) outside the heating device (10) comprising at least the following steps: a) Partial or complete lifting of a thermoplastic fiber composite panel (2) by means of at least one levitation unit (30) arranged in the area of ​​the heating device (10), which is designed to act on the underside of the fiber composite panel partially or completely with a plurality of force components counteracting the force of gravity, wherein adjustable operating parameters of the levitation unit (30) are controlled by means of a control (34) such that a stable horizontal lifting state of the fiber composite panel (10) is produced at a constant distance to a transport plane (35); b) Heating the fiber composite panel (2) to a material-dependent softening point at temperature T w ; as well as c) Transport of the heated fiber composite panel (2) to the subsequent station (20).

Description

[0001] The invention relates to a method according to claim 1 and a device according to claim 8. The invention accordingly relates to a method and a device for transporting, in particular, thermoplastic fiber composite panels which are to be heated and which have been heated.

[0002] In the current state of the art, fiber composite components with a thermoplastic matrix are typically manufactured from pre-impregnated and consolidated sheets. Such pre-impregnated and consolidated sheets are heated to the desired process temperature using a suitable heat source. A special furnace or radiant heating field, for example, is used as a heat source to heat the thermoplastic matrix to its intended softening point. Compared to thermoset fiber composites, thermoplastic fiber composites offer, among other advantages, the ability to achieve shorter cycle and process times, which in turn influences the manufacturing costs of thermoplastic forming and transport processes.

[0003] After heating the pre-impregnated and consolidated fiber composite panels, they must be transported to a forming station, such as a press, where the heated fiber composite panels are formed and then cooled.

[0004] However, once the fiber composite panels have been heated to the desired process temperature, at which the thermoplastic matrix becomes soft and sticky, undesirable damage occurs to both the fiber composite panels and the device for heating the fiber composite panels, as they bond to the support. This bonding makes the fiber composite panels difficult to remove and transport. Furthermore, this creates imperfections and surface defects, and adhesive residue adheres to the support in the heating device. These adhesive residues contaminate the support and decompose, particularly in the heating section. They are then carried along with one of the subsequent fiber composite panels or adhere to its softened surface.

[0005] In the prior art, it is known from other technical fields to transport panels via rollers, but this cannot be transferred to the softened fiber composite panels and would also lead to the problems mentioned. The rollers transport and support the loads. It is unavoidable that the rollers come into contact with the loads. Depending on the temperature and / or pressure of the part being transported on the roller, this contact can lead to surface damage and defects. Due to the point or linear contact area of ​​the rollers, the material stress is correspondingly high, so damage to such an arrangement is to be expected with heated fiber composite panels.

[0006] Alternatively, suspension devices are known for moving loads. The load is moved along a support rail using rollers mounted above the load that roll along the support rail. A disadvantage is that such suspension devices do not always move with the desired ease and smoothness, and deformations can occur when fiber composite panels soften due to their own weight.

[0007] From DE 102006004891 A1 a solution for transporting loads is known in which the weight of the load is completely supported by a permanent magnetic attraction force, so that an air gap is present between the support element and the permanent magnet.

[0008] In the flat glass industry, it is common practice to transport and support endless flat glass ribbons following the hot forming of a glass melt (e.g., by floating, drawing, or rolling) over roller fields. They are then moved away from the forming area, subjected to controlled cooling or tempering, and then separated into flat glass sheets after cooling or tempering. Transport rollers are also used here. It is known that such contact and the resulting surface defects on the glass ribbon can be avoided by using additional supporting gas cushions.

[0009] Document DE 101 41 498 A1 describes a roller table for supporting and conveying a hot glass ribbon, comprising a plurality of rollers arranged parallel to one another and perpendicular to the conveying direction of the glass strand, and which are rotatable about their own longitudinal axes; at least some of the rollers are sleeves, the casing of which is gas-permeable at least on part of its surfaces and has a gas connection on at least one of its end faces.

[0010] Further printed prior art in the present technical field is disclosed in the documents DE 21 03 622 A, DE 24 32 726 A1, DE 27 54 717 A1, DE 10 2010 053 332 A1 and DE 10 2006 004 891 A1.

[0011] All the above-mentioned and other previously known devices and methods are solutions adapted to specific manufacturing conditions, which cannot be applied to the use for heating and transporting thermoplastic fiber composite panels or which do not completely eliminate the aforementioned problems, but rather entail further problems which arise due to the stickiness of the softened fiber matrix during heating.

[0012] It is therefore an object of the present invention to overcome the aforementioned disadvantages and to provide a method for transporting, in particular, sticky heated fiber composite panels, which on the one hand avoids surface defects on the fiber composite panels and on the other hand avoids adhesive residues on the heating device and / or the transport device and the like.

[0013] This object is achieved by a method having the features of claim 1 and by a device having the features of claim 8.

[0014] The basic idea of ​​the present invention is to bring the fiber composite panel to be heated and transported in its heated and sticky state into a partial or complete lifting state (possibly a floating state) by means of a levitation unit designed according to the invention, so that no contact occurs between the fiber composite panel and the solid base during transport of the fiber composite panel. Thus, the fiber composite panel should be at least partially lifted by levitation. Thus, according to the invention, the fiber composite panel can be lifted in an edge region by means of a lifting device, while the central part of the panel, which has been bent due to softening, is lifted by levitation. For this purpose, a levitation device with a plurality of force introduction components is provided according to the method.This allows the fiber composite panel to be lifted by levitation despite softening and the associated weakening of its dimensional stability, thereby bringing the panel into a transport state without contact with the base, preferably by distributing the total force required to achieve the lifting or floating state into a plurality of force components across the entire surface of the panel. This is preferably achieved using a levitation unit designed to have a plurality of force components spaced apart from one another in a plane, the sum of which corresponds to and counteracts the weight of the fiber composite panel. For this purpose, the levitation unit can, for example, have force sources distributed across the surface to generate the required force components.In other words, the levitation unit can be designed as a matrix of sub-units, each of which generates a force component in the opposite direction to the weight of the fiber composite panel, so that the panel is positioned in a floating position in space, with no direct contact with the base.

[0015] In a preferred embodiment of the invention, a method for transporting thermoplastic fiber composite panels to be heated and heated along a heating section of a heating device to a subsequent station outside the heating device is proposed, comprising at least the following steps: - Partial or complete lifting of a thermoplastic fiber composite panel by means of at least one levitation unit arranged in the region of the heating device, which is designed to partially or completely apply a plurality of force components counteracting the weight of the panel to the underside of the fiber composite panel; (Alternatively: placing a fiber composite panel in a contactless levitation state in this area by at least one levitation unit arranged in the area of ​​the heating device); - Heating the thermoplastic fiber composite panel (2) to a material-dependent softening point at temperature T w and - Transport of the heated fiber composite panel to the next station.

[0016] The first two steps can also be carried out in reverse order or in parallel.

[0017] In the process, a gaseous medium (preferably air) is located below the fiber composite plate as a carrier medium, which is excited by the levitation unit.

[0018] In a further preferred embodiment of the invention, the lifting / floating state of the fiber composite panel is achieved by means of an acoustic levitation unit. It is particularly advantageous if the levitation unit comprises a plurality of levitation subunits arranged flatly (preferably uniformly) beneath the fiber composite panel.

[0019] In a particularly advantageous embodiment of the method according to the invention, a plurality of ultrasonic pressure nodes are formed, preferably in rows and columns, in a planar manner in a plane below the fiber composite plate.

[0020] In an alternative embodiment of the invention, the lifting state of the fiber composite panel can be achieved by means of a compressed air levitation unit by creating a supporting air cushion layer beneath the fiber composite panel. Preferably, the air cushion layer is formed between the underside of the fiber composite panel and the top side of the compressed air levitation unit.

[0021] It is also advantageous if the thickness of the air cushion layer is kept constant, thus achieving a stable lifting state. The same applies to a lifting state created by other means.

[0022] If the lifting state of the fiber composite panel is achieved using a compressed air levitation unit, it is particularly advantageous if the compressed air levitation unit forms a plurality of openings (holes) beneath the fiber composite panel through which a compressed air flow can be directed in a targeted manner. In this way, the openings form levitation subunits that are distributed over a large area (preferably evenly) beneath the fiber composite panel and can ensure a stable lifting state.

[0023] The number and thus density of the openings or levitation subunits can be selected depending on the size of the fiber composite panel. A grid spacing of approximately 1 mm to 2 cm between the openings or levitation subunits is preferred. However, the levitation subunits do not necessarily have to be evenly distributed across the surface. An irregular "network" of, for example, ultrasonic pressure nodes can also be formed to levitate the heated fiber composite panel.

[0024] In a particularly advantageous embodiment of the method according to the invention, however, a plurality of ultrasonic pressure nodes are formed in rows and columns, namely flat in a plane below the fiber composite plate.

[0025] In a further alternative embodiment of the invention, the method can also be used for fiber composite panels with embedded magnetic substances and the lifting state of the fiber composite panel can then be achieved by means of a magnetic levitation unit.

[0026] A further aspect of the present invention relates to a device for carrying out the method described above. According to the invention, the device comprises a heating device and a levitation unit for bringing fiber composite panels into a contactless lifting state, spaced from a transport plane.

[0027] According to the invention, the device further comprises a controller for controlling adjustable operating parameters of the levitation unit to establish a stable lifting state of a fiber composite panel, namely a stable horizontal levitation state with a constant distance from a transport plane. Especially with a high density of subunits for generating the required force components, such as the ultrasonic pressure nodes, a planar sound field can be generated by targeted adjustment of the ultrasonic waves, wavelength, etc.

[0028] It is further advantageous if the plurality of force generation sources counteracting the weight force F of the fiber composite panel are arranged in rows and columns spaced apart from a transport plane, so that a total force uniformly distributed on the underside of the fiber composite panel acts, which compensates for the weight force.

[0029] Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0030] They show: Fig. 1 a schematically illustrated device according to the invention for transporting heated thermoplastic fiber composite panels; Fig. 2 a plan view of the device according to Fig. 1 and Fig. 3 a schematic flow diagram of the method according to the invention.

[0031] In the Fig. 1 and Fig. 2 is a schematically illustrated device 1 according to the invention for transporting thermoplastic fiber composite panels 2 to be heated or heated, for example, to a subsequent station 20. The device 1 is shown in a side view ( Fig. 1) and once in a supervision ( Fig. 2). The device 1 is designed to carry out the method described in the description of Fig. 3. The device 1 comprises a machine frame 5, a heating device 10 arranged above the machine frame 5, and a levitation unit 30 for bringing a fiber composite panel 2 into a contactless lifting state spaced from the transport plane 35. The heating device 10 defines a heating section 11 along which the fiber composite panel 10 is heated. The device 1 further comprises a controller 34 for controlling adjustable operating parameters of the levitation unit 30 in order to be able to establish a stable lifting state of a fiber composite panel 2, preferably a stable horizontal lifting state with a constant distance from the transport plane 35 shown. The control unit 34 has a display 34a on which preset material- and size-dependent parameters can be selected or adjusted by an operator.

[0032] It is in Fig. 2 that the levitation unit 30 is designed such that a plurality of force-generating sources 36 are provided that counteract the weight F of the fiber composite panel 2 and are arranged in rows and columns at equal intervals. The force-generating sources 36 are openings through which compressed air can flow evenly to the underside 3 of the fiber composite panel 2 to create an air cushion there.

[0033] In the Fig. Figure 3 shows a schematic flow diagram of the method according to the invention. The method for transporting heated thermoplastic fiber composite panels 2 along a heating section 11 of a heating device 10 to a subsequent station 20 outside the heating device 10 comprises at least the following steps: i) placing the thermoplastic fiber composite plate 2 into a contactless lifting state by at least one levitation unit 30 arranged in the region of the heating device 10, and ii) Heating the fiber composite panel 2 to a material-dependent softening point at temperature T w ; as well as iii) Transport of the heated fiber composite panel 2 to the subsequent station 20.

[0034] The subsequent station 20 can, for example, be a forming press with an upper press part 20a and a lower process part 20b.

[0035] The lifting state of the fiber composite panel 2 is achieved here by means of a compressed air levitation unit 30 by creating an air cushion layer 33 beneath the fiber composite panel 2. The air cushion layer 33 is thus formed in the process between the underside 3 of the fiber composite panel 2 and the top side 31 of the compressed air levitation unit 30. The thickness of the air cushion layer 33 is kept stable and constant by means of a control system, so that a stable lifting state is achieved.

[0036] The invention is not limited to the preferred embodiments described above. Rather, a number of variants are conceivable that utilize the presented solution even in fundamentally different embodiments.

Claims

[1] Method for transporting heated thermoplastic fiber composite panels (2) along a heating section (11) of a heating device (10) to a subsequent station (20) outside the heating device (10), comprising at least the following steps: a) Partial or complete lifting of a thermoplastic fiber composite panel (2) by means of at least one levitation unit (30) arranged in the region of the heating device (10), which is designed to partially or completely apply a plurality of force components counteracting the weight to the underside of the fiber composite panel, wherein adjustable operating parameters of the levitation unit (30) are controlled by means of a controller (34) in such a way that a stable horizontal lifting state of the fiber composite panel (10) is produced at a constant distance from a transport plane (35); b) Heating the fiber composite panel (2) to a material-dependent softening point at temperature T w ; as well as c) Transport of the heated fiber composite panel (2) to the subsequent station (20). [2] Method according to claim 1, wherein the lifting of the fiber composite panel (2) in its edge region is carried out by means of a mechanical lifting device and the lifting of the fiber composite panel in the remaining (central) panel region is achieved by means of the levitation unit (30), preferably by means of an acoustic levitation unit (30). [3] Method according to one of the preceding claims 1 or 2, wherein a plurality of ultrasonic pressure nodes are formed, preferably in rows and columns, in a planar manner in a plane below the fiber composite plate. [4] Method according to claim 1, wherein the lifting state of the fiber composite plate (2) is achieved by means of a compressed air levitation unit (30) by creating an air cushion layer (33) below the fiber composite plate (2). [5] Method according to claim 4, wherein the air cushion layer is formed between the underside (3) of the fiber composite plate (2) and the upper side (31) of the compressed air levitation unit (30). [6] Method according to claim 4 or 5, wherein the thickness of the air cushion layer (33) is kept constant and thus a stable lifting state is achieved. [7] Method according to claim 1, wherein a magnetic substance has been embedded in the thermoplastic fiber composite plate (2) and the lifting state of the fiber composite plate (2) is achieved by means of a magnetic levitation unit (30). [8] Device (1) for carrying out the method according to one of claims 1 to 7, wherein the device (1) comprises a heating device (10) and a levitation unit (30) for bringing fiber composite panels (2) into a non-contact lifting state with the base to a transport plane (35), characterized by that a controller (34) is further provided for controlling adjustable operating parameters of the levitation unit (30) in order to establish a stable horizontal lifting state of a fiber composite panel (10) at a constant distance from a transport plane (35). [9] Device (1) according to claim 8, wherein the levitation unit (30) is designed such that a plurality n of force generation sources (36) are provided which counteract the weight force F of the fiber composite plate (2), which are preferably arranged in rows and columns spaced apart from a transport plane (35).

Images