METHOD OF MAKING A CONSTRUCTION PANEL

Abstract

The invention relates, inter alia, to a method of making a thin component (10) in a lightweight sandwich construction having a high-quality surface (26).

Claims

1. A method of making a thin component in a lightweight sandwich construction having a high-quality surface, the method comprising the following steps: i) providing granular starting material in the form of loose granular particles of an expandable particle foam, that, when expanded, have a softening temperature of greater than 160 C., ii) expanding the granular particles, iii) introducing the expanded, granular particles in the form of a granulate into a cavity of a lower mold part of a mold, iv) closing the mold, v) heating the mold, vi) baking the expanded particles in the mold to form a homogeneous curable particle foam, vii) curing the particle foam to form a molded body, viii) opening the mold and removing the molded body therefrom, ix) applying a coating layer to a face of the molded body, and x) drying the coating layer.

2. The method according to claim 1, wherein step ix) and/or step x) are carried out at a temperature of above 150 C. and below the softening temperature of the expanded particle foam.

3. The method according to claim 1, further comprising the steps, before step iii), of: a) providing a film-like substrate, b) fitting the substrate into the lower mold part of the mold.

4. The method according to claim 3, wherein the substrate is a deep-drawn film.

5. The method according to claim 3, further comprising the step of: xi) applying a cover layer to a face of the particle foam directed away from the substrate.

6. The method according to claim 1, further comprising the step of: xii) processing the molded body to form a component.

7. The method according to claim 3, wherein the substrate has a wall thickness of between 0.05 mm and 13 mm.

8. The method according to claim 1, wherein the cured particle foam has a wall thickness of between 1 cm and 30 cm.

9. The method according to claim 1, wherein the component is a vehicle part for a truck or for a commercial vehicle or for a trailer.

10. The method according to claim 1, wherein the starting material is provided y expandable EPS, PP, PPSU, PSU or PEEK.

11. The method according to claim 1, further comprising, before carrying out step vi), the following step: xiii) positioning reinforcing elements in the lower mold part such that the expanded particles surround the reinforcing elements after the particles have been introduced into the lower mold part.

12. The method according to claim 1, wherein the dried coating layer applied to the molded body has a wall thickness of between 0.01 mm and 2 mm.

13. The method according to claim 1, wherein the step of applying a coating layer takes place as part of a cathodic dip coating method.

14. The method according to claim 1, wherein the step of applying a coating layer takes place as part of a powder coating method.

15. The method according to claim 1, wherein step ii) of expanding the particles entails only partially expanding the particles, during step iii) the partially expanded particles are introduced into the lower mold part, and during step vi) the partially expanded particles are baked and completely expanded.

16. The method according to claim 1, wherein in step ii) the particles are completely expanded.

17. A thin component having a high-quality surface and comprising: a cured particle foam that has a softening temperature of greater than 160 C. a coating layer on the component.

18. The component according to claim 17, wherein the component comprises a film between the particle foam and the coating layer and having a wall thickness of between 0.2 mm and 13 mm.

19. The component according to claim 17, wherein the cured particle foam has a wall thickness of between 1 cm and 30 cm.

20. The component according to claim 18, wherein the particle foam is expanded against the substrate.

Description

[0078] Other advantages of the invention become apparent from the dependent claims that have not been cited, as well as with reference to the following description of the embodiments shown in the drawings, in which:

[0079] FIG. 1 is a partially sectional schematic view of an embodiment of an oven, into which granular starting material in the form of particles of a particle foam is being poured, the granular starting material being unexpanded,

[0080] FIG. 2 shows the oven from FIG. 1, with an infrared radiant heater additionally being shown, the particles that were previously poured in having been brought into a partially expanded state,

[0081] FIG. 3 shows a first mold comprising a lower mold part and an upper mold part and a film that is a web-shaped, flat state in the form of a substrate,

[0082] FIG. 4 shows the closed mold from FIG. 3 with the deep-drawn film,

[0083] FIG. 5 shows another mold, in which the deep-drawn film from FIG. 4 is positioned, the partially expanded particles of the particle foam according to FIG. 2 being poured into the lower mold part,

[0084] FIG. 6 shows the mold from FIG. 5 with the additionally shown upper mold part just before the mold is completely closed,

[0085] FIG. 7 shows the tool from FIG. 6 in a completely closed state, with a heating device for the mold additionally being shown,

[0086] FIG. 8 shows the tool from FIG. 7 in an open state with the completely expanded, cured particle-foam mass,

[0087] FIG. 9 shows the molded body removed from the mold from FIG. 8 and shows cutting lines along which the excess regions of the substrate are cut off,

[0088] FIG. 10 shows another embodiment of a molded body or a component according to the invention formed in a method according to the invention, comprising an additional layer on the face of the cured particle-foam mass directed away from the substrate,

[0089] FIG. 11 shows another embodiment of a component according to the invention in a view according to FIG. 10, wherein, solely for the purposes of illustration, the pore structure of the cured particle foam is shown such that it is altered compared with FIG. 10,

[0090] FIG. 12 shows, in order to illustrate a step of applying a coating layer in an embodiment of the method according to the invention, the molded body or the completed component according to FIG. 9, after cutting off the excess regions, so as to be arranged in an immersion bath for carrying out a cathodic dip coating step,

[0091] FIG. 13 shows just the component that has been removed from the immersion bath from FIG. 12 and is now provided with a coating layer,

[0092] FIG. 14 shows the coated component according to FIG. 13 in a drying apparatus,

[0093] FIG. 15 shows a lower mold part in a view according to FIG. 5, into which expanded particles are introduced, with no substrate being arranged in the lower mold part, by contrast with the embodiment in FIG. 5,

[0094] FIG. 16 shows, in a view according to FIG. 14, a step in the process for drying a component that is provided with a coating layer, has been made following a method according to FIG. 15, and comprises a coating layer but not a substrate, and

[0095] FIG. 17 shows, in a view according to FIG. 12, the application of a coating layer to a molded body according to FIG. 9 by an application apparatus as part of a powder coating method.

[0096] Embodiments of the invention are described by way of example in the following description of the figures, also with reference to the drawings. Here, for the sake of clarity, even if different embodiments are involved, identical or comparable parts or elements have been denoted by identical reference signs, sometimes with the addition of lower case letters.

[0097] Features that are only described, set out or disclosed in relation to one embodiment can also be provided in any other embodiment of the invention within the scope of the invention. Even if they are not shown in the drawings, such amended embodiments are covered by the invention.

[0098] All the features disclosed are essential to the invention per se. The content of the disclosure of the associated priority documents (copy of the previous application) and the cited documents and the prior art devices described are hereby incorporated into the disclosure of the application in their entirety, also for the purpose of incorporating individual features or a plurality of features of the subjects disclosed therein into one or more claims of the present application. Even if they are not shown in the drawings, such amended embodiments are also covered by the invention.

[0099] In the following, proceeding from FIG. 1, the method for manufacturing a component 10 shall be set out:

[0100] According to FIG. 1, a container 12 is shown into which a granulate 11 of a particle foam is poured. The individual granulate particles, which are denoted by reference signs 30a, 30b, 30c by way of example, are unexpanded, and constitute the starting material for manufacturing a particle foam. Greater detail will be given in the following regarding the individual materials that can be used in the method according to the invention.

[0101] According to FIG. 2, the container 12 is part of an oven 13 in which the granulate particles 30a, 30b, 30c can be partially expanded:

[0102] For this purpose, a heater 14, in particular an infrared heater 14, is provided, which introduces a predetermined radiant power into the oven 13 using infrared rays 15 (indicated), in order to reach a certain temperature or a certain temperature range. The granulate particles 30a, 30b, 30c are subjected to the effects of the temperature in the oven 13 for a predetermined time and partially foam. It can be seen that the individual particles 30a, 30b, 30c in FIG. 1 considerably increase in volume and, according to FIG. 2, turn into partially expanded particles 31a, 31b, 31c. It should be noted that the drawings should not be understood as being to scale, but instead that the process of expanding and the increases in volume are only intended to be shown by way of example.

[0103] The partially expanded particles 31a, 31b, 31c are still loose, in particular not joined to one another. During the process of partially expanding according to FIG. 2, by additional measures such as shaking the container 12, stirring, using chemicals, or introducing chemicals into the container 12, it can be achieved that the particles 31a, 31b, 31c do not become joined to one another or predominantly do not become joined to one another, but instead can still be transported as a loose, pourable or at least free-flowing mass. According to FIG. 5, this mass is poured into a lower mold part 23 of a mold 17b.

[0104] The production of the substrate 21 shall first be explained with reference to FIGS. 3 to 4:

[0105] According to FIG. 3, a first mold 17 is provided that comprises an upper mold part 18 and a lower mold part 19. The relevant mold parts can be designed in the manner of a female mold and in the manner of a male mold. FIG. 3 shows a film 20 in a flat, web-shaped state, i.e. an initial state. FIG. 3 shows the mold when open.

[0106] Owing to the mold being closed, the film 20 is deep-drawn from the flat state. The deep-drawing process can impart any spatial contour to the film. The deep-drawing process can be assisted by temperature in a conventional manner, and this is not shown in the drawings. For the deep-drawing process, as an alternative to the embossing/molding process used in the mold 17 in FIG. 3, blow-molding methods, or other shaping methods in which the film is heated and brought into its final shape by applying a vacuum are also possible.

[0107] After opening the mold 17 from the state in FIG. 4, the deep-drawn film 21 can be removed and transported to another mold. A second mold 17b of this kind is shown in FIGS. 5 to 8.

[0108] The invention also covers the case in which the film 21 remains in the lower mold part 19 after the deep-drawing process, and only the upper mold part is changed. In the following, it is assumed that, proceeding from FIG. 5, the deep-drawn film 21 has been placed into another, second lower mold part 23 of another mold 17b.

[0109] According to FIG. 5, the pourable or free-flowing mass made of partially expanded particles 31a, 31b, 31c is placed into the lower mold part 23 in a cavity 22 that serves to receive the partially expanded particles 31a, 31b, 31c and faces the rear face 35 of the deep-drawn film 21. The filling of the second lower mold part 23 or the cavity 22 provided therefor can be carried out manually or by a machine or in a machine-assisted manner until a predetermined volume or predetermined mass of partially expanded particles 31a, 31b, 31c is positioned and in particular distributed in the cavity 22.

[0110] Here, a delivery or output device (not shown in the drawings) may be provided that evenly distributes the particles along the cavity 22 in the manner of a feed head.

[0111] The mold 17b is then closed. For this purpose, an upper mold part 24 is moved into a closed state, starting from a state according to FIG. 6 in which the mold 17b is still partially open. The cavity 22 is then closed on all sides.

[0112] FIG. 7 shows a heater 25 that temperature-controls the mold 17b, preferably both the lower mold part 23 and the upper mold part 24. The mold temperature is selected depending on the materials used for the particle foam.

[0113] In particular, it is provided that the mold is temperature-controlled to a mold temperature that is above the VICAT softening temperature, in order to make it possible to carry out the baking step. After an intended period of action of the temperature, it is provided that the mold temperature is reduced to a temperature below the VICAT softening temperature in order to initiate the curing process.

[0114] Owing to the action of the temperature, the partially expanded particles 31a, 31b, 31c are completely expanded. A honeycomb structure can be seen in FIG. 8, and is merely indicated by way of example. This structure can likewise only be understood to be schematic; in fact, the structure of the completely expanded particle foam is irregular. Another comparable structure is shown in FIG. 11:

[0115] Here, instead of the frame structure in FIG. 8, an irregular, polygon-like structure is shown in a schematic sectional view.

[0116] FIG. 8 makes it clear that the partially expanded particles 31a, 31b, 31c according to FIG. 7 turn into completely expanded particles 32a, 32b, 32c, with there no longer being any spaces between individual expanded particles 32a, 32b, 32c. However, FIG. 7 still shows such spaces, denoted by reference sign 36 by way of example.

[0117] It should be noted that the expression completely expanded particles 32a, 32b, 32c is misleading:

[0118] In fact, the large number of completely expanded particles 32a, 32b, 32c overall forms a completely expanded particle-foam mass 33 or a completely expanded particle foam. According to FIG. 8, this can also cure within a short time, such that, as shown by FIG. 8, the mold can be opened and the upper mold part 24 can be raised from the lower mold part 23. The molded body 10 thus formed can then be removed from the mold.

[0119] Owing to the process of complete expanding, with the mold closed, the particle foam becomes permanently and firmly joined to the inner face 35 of the deep-drawn film 21. As a result, a light, rigid and load-bearing composite component that can nevertheless be made cost-effectively is provided.

[0120] According to FIG. 9, if required, excess regions 34a, 34b of the film 21 can be cut off along the cutting lines 29a, 29b.

[0121] The embodiment in FIG. 10 shows the rear face 27 of the component 10 that can be provided with an additional layer 28, e.g. made of plastics material.

[0122] The invention also covers components in which, instead of a deep-drawn film 21 made of ABS or PMMA, a thin film made of polyethylene or polypropylene, or in particular also so-called slush skins, is used as the substrate 21, while ensuring that the deep-drawn film has a VICAT softening temperature in any case or, for a metal film, a melting point that is higher than the temperature applied in the step of applying the coating layer or the step of drying the coating layer that are to be carried out according to the invention.

[0123] FIG. 8 indicates, by way of example, the wall thicknesses W1 of the deep-drawn film 21 or of the substrate and W2, namely the wall thickness of the cured particle-foam mass 33. The wall thickness W1 may be between 0.2 mm and 13 mm, and the wall thickness W2 may be between 1 cm and 30 cm.

[0124] The invention also in particular covers components that are designed as caravan wall elements. For example, wall portions of a caravan trailer or a caravan, or complete wall elements of a caravan, can be used in vehicle construction, with the use of the method according to the invention.

[0125] The invention also covers further embodiments that provide that reinforcing elements are deposited in the cavity 22 before the cavity 22 is filled with partially expanded particles 31a, 31b, 31c.

[0126] The reinforcing elements (not shown in the drawings) may e.g. comprise reinforcing fibers. Owing to the cavity 22 being filled with partially expanded particles 31a, 31b, 31c, the particles are evenly distributed and envelop the reinforcing elements on multiple sides, preferably on all sides. The completed component 10 comprises a cured particle-foam mass that securely surrounds the reinforcing elements.

[0127] By positioning the reinforcing elements, tensile forces in particular can thus be transmitted or absorbed.

[0128] After cutting off the excess regions 34a, 34b or, in alternative variants of the invention, also before cutting off the excess regions 34a, 34b, the component 10 in FIG. 9 is subjected to a step of applying a coating layer 39. For this purpose, two different ways of applying a coating layer shall be explained according to FIGS. 12 and 17:

[0129] According to FIG. 12, after being made and removed from the mold, the component 10 in FIG. 9 is arranged in an immersion bath 37, in which a liquid, which is known as the immersion coating 38, is arranged. FIG. 12 shows the component 10 in the completely immersed state. The invention also covers variants in which only a portion of the component 10 that bears the surface to be coated is immersed.

[0130] According to FIG. 12, a step of cathodic dip coating takes place. In order to avoid repetition, the physical, chemical, and electrochemical aspects of this method that are known per se will not be discussed. In this case, known devices and methods can be used.

[0131] It should be noted that, when introducing the component 10, the immersion coating can have a high temperature of between 150 C. and 220 C., for example. Owing to the fact that, according to the invention, a starting material of an expandable particle foam has been selected that has a VICAT softening temperature of greater than 160 C., and that advantageously has an even higher VICAT softening temperature, this step of immersion coating can be carried out in the first place for the purpose of applying a coating layer 39.

[0132] FIG. 13 shows the component 10 after it has been removed from the immersion bath 37, and to which a coating layer 39 is then adhered.

[0133] In order to dry the coating layer 39, the component 10 is then transported to a drying device 40. Said device may comprise one or more drying units 40a, 40b that ensure that a high temperature is applied to the component 10. The following applies here: the higher the temperature, the shorter the required dwell time of the component in the drying device 40 and the shorter the drying time.

[0134] It should be noted that, according to the invention, the component having the applied coating layer is exposed to a temperature that is in particular higher than 150 C. for the purpose of drying the coating layer. It is also noted that, according to a variant of the invention, the component 10 is exposed to a temperature that is below the VICAT softening temperature of the particle foam for the purpose of drying the coating layer 39.

[0135] The arrow 41 in FIG. 14 indicates that the component 10 can be moved relative to the drying apparatus 40a, 40b while drying the coating layer 39. Alternatively, the drying apparatus 40, 40a can also be moved relative to the stationary component 10.

[0136] According to the embodiment in FIG. 15, it is indicated that, as an alternative to manufacturing a component 10 that comprises a substrate or a film 21, the expanded particles 31a, 31b, 31c can also be placed directly into the lower mold part without a film 21 having been arranged therein in advance. The component 10 according to the invention can thus be directly manufactured from such an expandable particle foam.

[0137] If, proceeding from the view according to FIG. 15, the cavity 22 in the lower mold part 23 is completely filled with expanded particles 31a, 31b, 31c and the upper mold part (not shown in FIG. 15) is then moved into a closed position against the lower mold part 23, and the particles bake together, a bare component that does not have a film or a substrate is made in this respect.

[0138] Such a component can, as shown in FIG. 16, likewise have a coating layer 39 applied thereto:

[0139] FIG. 16 shows that, according to a view according to FIG. 14, a coating layer can also be applied directly to the cured particle foam and a step of drying can subsequently be carried out.

[0140] According to FIG. 17, as an alternative to the cathodic dip coating process, the application of a coating layer 43 as part of a powder coating method is explained: according to FIG. 17, using an application device 42, e.g. a coating gun, a powder coating layer 43 is applied to a component 10 according to FIG. 9. This component can also be guided through a drying apparatus according to FIG. 14 after the application in order to dry the coating layer.

[0141] The embodiments in FIGS. 1 to 11 describe variants of the invention in which the loose granular particles 30a, 30b, 30c made of starting material are first pre-expanded, in the container 13, and are completely expanded in the mold 23 during the baking process. However, the invention also covers variants in which particles are completely expanded in the container 13 and are placed into the mold 23 as loose, granular, completely expanded particles 31a, 31b, 31c and are sintered or baked to one another therein over the course of the baking without an increase in the volume of the expanded particles 31a, 31b, 31c taking place therein.