Building product and method

Description

[0001] The invention relates to a light well with the features of the preamble of claim 1. Such a light well is known, for example, from US 6,484,455 B1. The invention further relates to a method for manufacturing a light well.

[0002] From the aforementioned US 6,484,455 B1, a light well with a wall structure consisting of several plastic layers is known. The wall structure comprises an outer layer and an inner layer with a foam core between them. The outer and inner layers are made of high-density polyethylene, and the foam core is made of low-density linear polyethylene. The light well can be manufactured by injection molding. A light well according to the preamble of claim 1 is known from the aforementioned document.

[0003] EP 1 247 912 A2 describes a construction product that is a drainage channel for surface drainage systems. The known drainage channel is made of plastic and has a closed-cell foam structure to ensure the necessary watertightness for such drainage channels. Other construction products made of foamed plastic are known, for example, from GB 1 378 552 A1 in the form of a light well and from DE 1 936 524 A1 as a rain gutter. To improve the rigidity of construction products made of foamed plastic, the wall thickness of such products is increased by using appropriate amounts of material.

[0004] The invention is based on the objective of improving a light well of the type mentioned above in such a way that the stiffness or buckling resistance of the wall structure is increased with the least possible use of material. The invention is further based on the objective of providing a method for manufacturing a light well.

[0005] According to the invention, the problem is solved with regard to the light shaft by the subject matter of claim 1 and with regard to the method by the subject matter of claim 8.

[0006] Specifically, the task is solved by a light well with a wall structure that is at least partially made of foamed plastic material. The plastic material has a foam structure and a density that varies depending on the wall cross-section.

[0007] The invention has the advantage that the stiffness or buckling resistance of the wall structure is achieved not solely through the amount of material used, but rather through a targeted modification of the density of the plastic material. In other words, the density is increased in the areas of the wall structure subjected to particularly high stress. Compared to the prior art, comparable stiffness values ​​of the wall structure can therefore be achieved with less material. The invention thus makes it possible to produce light wells with minimal material usage using foamed plastic materials, whereas previously the required stiffness or buckling resistance values ​​could only be achieved using solid or compact materials.

[0008] It is possible that the wall structure exhibits a foam structure across its entire cross-section, with varying density across different areas. It is also possible that the density of the plastic material is so high in certain areas that it exhibits a compact material structure rather than a foam structure. In this case, other areas of the wall structure retain the foam structure. Layered structures, where one layer forms the foam structure and another layer a compact structure, are an example of this.

[0009] Preferred embodiments of the invention are specified in the dependent claims.

[0010] According to the invention, the density decreases from the outer and / or inner surface of the wall structure towards the interior of the wall. This has the advantage of providing particularly good stabilization of the wall structure. This embodiment is applicable to a wall structure that, with respect to its cross-section, is entirely composed of a foam structure. In this case, the foam structure extends to the outer and / or inner surface of the wall structure. This embodiment is also applicable to a wall structure in which a compact or solid structure is present in some areas and a foam structure in others. The compact or solid structure has a higher density than the foam structure, so that different density zones are also present here. According to the invention, the plastic material is the same throughout the entire wall cross-section. The wall cross-section is therefore monolithic.

[0011] According to the invention, the foam structure is formed at least in one area of ​​the wall structure that is arranged further inwards in the width direction with respect to the outside and / or inside. This has the advantage that the foam structure in general, or the area of ​​the foam structure with the lower density, is arranged further inwards with respect to the surroundings of the wall structure, thus improving the stability of the wall structure.

[0012] The plastic material has at least one layer. This embodiment is particularly suitable for applications where the plastic material is formed in certain areas, i.e., in this case layer by layer, as a compact or solid material that borders another area of ​​the wall structure with the foam structure.

[0013] According to the invention, the plastic material forms a cover layer, in particular a compact cover layer, on the outside and / or inside of the wall structure. This embodiment is particularly, but not exclusively, suitable for light wells with relatively thin walls. In this context, one speaks of integral foams, which have a core of foam cells and a cell-free or cell-poor outer region, which can also be described as a compact cover layer.

[0014] If the thickness of the layer, especially the top layer, is constant at least in certain areas along the wall structure, the properties of the light shaft can be precisely and selectively adjusted along the wall structure.

[0015] It has proven advantageous if, in the case of light wells, the thickness of the covering layer is at least 0.5 mm to 1.5 mm in some areas, and in particular 0.5 mm to 1.0 mm.

[0016] The foam structure can have a density in the range of 0.5-1.0 kg / m 3< , in particular approximately 0.7 kg / m 3< .

[0017] If the wall structure has areas with varying wall thicknesses, the light well can be reinforced locally. For example, it is possible that the wall structure has at least one functional area where the wall thickness is greater than that of another area.

[0018] With regard to the method, the object of the invention is achieved by a method for producing a light shaft according to the invention. In the method, a plastic material is foamed in an injection mold and cooled in the injection mold to form a foam structure. An advantage of the method according to the invention is that the wall thickness of the wall structure can be varied without the material sagging in areas of increased wall thickness.

[0019] In general, for the invention and the embodiments described below, PP plastic is used as the plastic material. Other foamable plastics are possible.

[0020] The invention is explained in more detail below with reference to an exemplary embodiment and the accompanying schematic drawings.

[0021] These show Fig. 1 a perspective view of a light well according to an embodiment of the invention with the side facing the house in the installed state; Fig. 2 a perspective view of the light well according to Fig. 1 with the side facing away from the house in the installed state and Fig. 3 a section through the wall cross-section of the light shaft according to Fig. 1 to illustrate the foamed plastic.

[0022] The one in the Figuren 1, 2 The depicted light well is installed as a basement light well and protects the basement from rising groundwater and backflow. At the same time, the light well allows good light penetration into the basement rooms located behind the basement window. The special feature of this light well is its wall structure 10 made of a foamed plastic material, with varying density in different areas. The density profile or density difference of the wall structure 10 is shown in Fig. 3 depicted. Fig. 3 shows a cross-section of the wall structure 10 according to Fig. 1 or Fig. 2 The edges of the cross-section according to Fig. 3 correspond to the outer surface 11 or the inner surface 12 of the wall structure 10, as shown in the Figuren 1, 2 depicted.

[0023] Out of Fig. 3 It is clearly evident that the plastic material has a foam structure and a density that varies by 10 times the cross-sectional area of ​​the wall structure. Specifically, the density of the plastic material is higher in the outer regions or layers than in the interior of the wall structure. The cells or pores of the foam structure are clearly visible in the interior. The outer regions show no cells or pores, or at least no visible cells / pores, and can be considered compact or solid material areas in comparison to the interior. The outer regions essentially form a skin that encloses the inner cellular area on both sides. These outer regions can also be described as surface layers. Fig. 3 This is an example of the plastic material or wall structure 10 being designed as an integral foam. In this case, the integral foam has a sandwich structure, with layers on both sides, i.e., on the side facing the wall. Fig. 1 The outer surface 11 and inner surface 12 shown each have a top layer.

[0024] In Fig. 3 It is also evident that the density of the plastic material decreases from the outer surface 11 and the inner surface 12 of the wall structure 10 towards the interior of the wall, i.e., towards the core. The porosity therefore increases towards the core. This applies, on the one hand, to the wall cross-section as a whole. In this case, the density of the edge regions is higher than the density of the foam core due to the compact structure of the plastic material. On the other hand, this also applies to the foam core itself. As in Fig. 3 As can be seen, the cell size of the foam core increases from the outside to the inside; that is, the cells located in the area of ​​the midline are larger than the cells located closer to the edges. This is accompanied by a decrease in density from the outside to the inside, also within the foam core.

[0025] When the plastic material is formed as an integral foam, the areas with different densities are clearly recognizable as different layers ( Fig. 3 ).

[0026] In Fig. 3 It can further be seen that the surface layers along the wall structure 10 are essentially constant. The preferred numerical ranges of the surface layer are at least in some areas 0.5 mm to 1.5 mm, in particular 0.5 mm to 1.0 mm. The density of the foam structure inside the wall structure 10 is 0.5–1.0 kg / m³, in particular 0.7 kg / m³. In comparison, the bulk density of the compact plastic material in the edge regions is approximately 1.2 kg / m³. Other density values ​​are possible.

[0027] The compact cover layers have the advantage of stabilizing the wall structure 10, so that the wall thickness can be smaller compared to a foamed wall structure with uniform or constant density across the entire wall cross-section in order to achieve comparable strength or stiffness values.

[0028] Generally speaking, light wells made of foamed plastic have the advantage of being lighter compared to similar concrete products. The main load on the light well according to Fig. 1The pressure exerted by the earth or water in front of the light well is a key factor. For this reason, the light well has a curved shape. Since the wall thickness is crucial in resisting the load, it should be particularly thick in this area, which in the prior art can only be achieved by using more material. In this embodiment according to the invention, the foam structure reduces the amount of material required.

[0029] The increased densities on the outer surface (11) and inner surface (12), combined with the comparatively lower densities in the interior (foam structure), create a cladding effect for the component. Despite the reduced material usage in the inner area of ​​the structure, similar strength properties are achieved for the light well compared to a solid light well. Despite the lower densities in the inner layer (middle layer) between the outer layers, the buckling strength / stiffness of the foamed structure is comparable to that of a solid structure.

[0030] Foamed structures are recognizable by optical irregularities on the surface of the building material products. These textured surfaces have a rougher surface compared to conventional injection-molded products. This can be advantageous for certain decorative applications, as it allows for the creation of a relief-like surface. This surface texture results from the bursting of gas bubbles in the hot, liquid foam on the surface of the component.

[0031] Generally, plastic light wells can be manufactured using injection molding. In the embodiment of the process according to the invention, the foam structure is achieved by foaming the plastic material in the injection mold. Products manufactured using this foaming process exhibit various characteristics. A key advantage is that light wells with a foamed structure can have different wall thicknesses at predefined locations. For example, in certain functional areas of a light well body, such as mounting areas or in other areas like the central section, greater wall thicknesses can be achieved using the foaming process. This is not possible with conventional injection molding processes, as these processes result in "sinkholes" in areas with greater wall thicknesses, leading to irregular surfaces and a loss of strength.The reason for this is that semi-crystalline plastics heat up, causing the atoms and molecular chains to vibrate. Upon cooling, the chains fold, resulting in a loss of volume. This state is then frozen in place by the cooling process. Due to the cooling of the molten plastic on the cooled inner surfaces of the injection mold, components produced using the injection foam process (integral foam) exhibit a relatively constant surface layer thickness in the range of 0.5 to 1.5 mm, particularly in the range of 0.5–1.0 mm. The surface layers on both sides of the light well have a higher density than the microcellular inner layer. While the surface layers have a bulk density of approximately 1.2 kg / m³, the foamed area has densities in the range of 0.5–1.0 kg / m³, particularly 0.7 kg / m³. Towards the interior of the component, the density can decrease further, as the size of the "gas bubbles" inside this integral foam-like product increases.Light wells are constructed of integral foam in the classic sense, with compact surface layers. In road drains, the surface layer (areas of higher density) may contain foam bubbles. This is not integral foam in the classic sense, as the different areas are not clearly demarcated.

[0032] In the functional areas of the component, the foaming process can advantageously be used to produce 3-dimensional structures, e.g., grid structures for the height adjustment of light shafts, in a cost-effective manner. Reference symbol list

[0033] 10 Wall structure 11 Exterior 12 Interior

Claims

1. A light shaft having a wall structure (10) formed at least partially from foamed plastics material, wherein the plastics material has a foam structure, wherein the plastics material forms a cover layer on the outer side (11) and / or on the inner side (12) of the wall structure (10), and the foam structure is formed at least in a region of the wall structure (10) arranged further inwards in the width direction relative to the outer side (11) and / or inner side (12), wherein the plastics material is the same across the entire wall cross-section, and the plastics material has a different density relative to the wall cross-section, characterised in that the density decreases starting from an outer side (11) and / or inner side (12) of the wall structure (10) towards the wall interior.

2. The light shaft according to claim 1, characterised in that the plastics material has at least one layer.

3. The light shaft according to claim 1 or 2, characterised in that the thickness of the layer, in particular the cover layer, is constant at least in some regions along the wall structure (10).

4. The light shaft according to any one of the preceding claims, characterised in that the thickness of the layer, in particular the cover layer, is at least in some regions 0.5 mm to 1.5 mm, in particular 0.5 mm to 1.0 mm.

5. The light shaft according to any one of the preceding claims, characterised in that the foam structure has a density in the range of 0.5-1.0 kg / m3, in particular about 0.7 kg / m3.

6. The light shaft according to any one of the preceding claims, characterised in that the wall structure (10) has regions of different wall thicknesses.

7. The light shaft according to any one of the preceding claims, characterised in that the wall structure (10) has at least one functional region the wall thickness of which is greater than the wall thickness of another region.

8. A method of manufacturing a light shaft according to any one of the preceding claims, wherein a plastics material is foamed in an injection mould and cooled to form a foam structure in the injection mould.