Double belt press

Abstract

Double belt press for continuous operation with a first circumferential lower steel belt (36; 96) and a second circumferential upper steel belt (38; 98), wherein an upper run of the first, lower steel belt faces a lower run of the second, upper steel belt, and wherein a forming section is formed between the upper run of the first lower steel belt and the lower run of the second, upper steel belt for forming a plate-shaped product, and wherein pressure devices are provided to apply a contact pressure in the forming section by means of the steel belts, with a first, lower circumferential plastic belt (12; 74) and a second, upper circumferential plastic belt (14; 75), wherein the plastic belts (12, 14; 74, 75) have a first, low bending stiffness, wherein a product gap (24; 78) is formed between the facing runs of the plastic belts (12, 14; 74, 75) for forming a plate-shaped product, wherein the steel bands (36, 38;96, 98) have a second, high bending stiffness compared to the bending stiffness of the plastic strips (12, 14; 74, 75), wherein a molded section (40; 100) is formed between the facing sections of the steel strips (36, 38; 96, 98), wherein the molded section (40; 100) forms part of the product gap (24; 78), wherein in the molded section (40; 100) during operation the first, lower steel strip (36; 96) runs parallel to and abutting a rear side of the first plastic strip (12; 74) facing away from the product gap (24; 78), and wherein in the molded section (40; 100) during operation the second upper steel strip (38; 98) runs parallel to and abutting a rear side of the second plastic strip (14;75) is characterized in that the pressure devices have sliding plates, wherein at least one first, lower sliding plate rests against a rear side of the upper run of the first, lower steel strip in the mold section and wherein at least one second sliding plate rests against a rear side of the lower run of the second, upper steel strip in the mold section.;

Description

[0001] The invention relates to a double belt press for continuous operation with a first circulating lower steel belt (36; 96) and a second circulating upper steel belt (38; 98), wherein an upper run of the first, lower steel belt is opposite a lower run of the second, upper steel belt, and wherein a forming section is formed between the upper run of the first lower steel belt and the lower run of the second, upper steel belt for forming a plate-shaped product, and wherein pressure devices are provided to apply a pressure in the forming section by means of the steel belts.

[0002] European patent EP 1 045 751 B1 discloses a double-belt press with a product gap between two partially parallel plastic belts. A thermoplastic pre-product is spread onto a lower plastic belt in a feed area and then formed into a sheet-like product between the two plastic belts in the product gap. The thermoplastic pre-product is bonded to form a stable sheet-like product by a quasi-pressureless welding process under a maximum pressure of 0.2 bar. This known double-belt press has disadvantages when it comes to producing thicker sheet-like products and / or processing fibrous pre-products, such as natural fibers, glass fibers, or carbon fibers.

[0003] The invention is intended to provide an improved double belt press.

[0004] According to the invention, a double belt press with the features of claim 1 is provided for this purpose.A double belt press for continuous operation is provided, comprising a first circulating lower steel belt (36; 96) and a second circulating upper steel belt (38; 98), wherein an upper run of the first, lower steel belt is opposite a lower run of the second, upper steel belt, and wherein a forming section is formed between the upper run of the first lower steel belt and the lower run of the second, upper steel belt for forming a plate-shaped product, and wherein pressure devices are provided to apply a pressure in the forming section by means of the steel belts, wherein the pressure devices have sliding plates, wherein at least a first, lower sliding plate bears against a rear side of the upper run of the first, lower steel belt in the forming section, and wherein at least a second sliding plate bears against a rear side of the lower run of the second, upper steel belt in the forming section.

[0005] Using sliding plates, uniform pressure can be applied to a sheet-shaped product in the mold section, with the pressure ranging, for example, from 0 bar to 5 bar. At 0 bar, the product is only touched, and the steel belts with the sliding plates are primarily used for temperature control. The sliding plates can be controlled either isochorically or isobarically. In isochoric operation, a fixed gap is maintained between the plates or between the steel belts. The applied pressure prevents this gap from changing, thus achieving a uniform product thickness. In isobaric operation, a defined pressure is applied to the sliding plates. The product thickness then adjusts itself according to the pressure level. The sliding plates can be used as standalone pressure devices or in combination with other pressure devices.The double belt press can be designed as a pure steel belt press or as a hybrid press, in which the steel belt press is integrated into a plastic belt press, for example a PTFE double belt press.

[0006] In a further development of the invention, the sliding plates with a region consisting of a sliding material are located on the back sides of the steel strips, wherein the sliding material is gray cast iron or graphite.

[0007] Gray cast iron or graphite have a low coefficient of friction with steel, thus minimizing wear. However, the sliding material is still a wear part and is replaced once a wear limit is reached.

[0008] In a further development of the invention, the area consisting of sliding material is designed as a replaceable sliding layer.

[0009] In this way, only a section of the sliding shoe needs to be replaced. Ideally, this replacement can be done without completely removing the sliding shoes. This keeps maintenance times short.

[0010] In a further development of the invention, means for applying lubricant to the back sides of the steel strips are provided.

[0011] Wear can be further minimized by wetting the back sides of the steel bands with lubricant, especially oil.

[0012] In a further development of the invention, means for temperature control of the sliding plates are provided.

[0013] The sliding plates can be heated electrically, with thermal oil, and / or with water. With electrical heating, temperatures up to approximately 500 degrees Celsius can be reached and precisely controlled. With thermal oil heating, temperatures between approximately 60 and 280 degrees Celsius can be reached and precisely controlled. With water heating, temperatures between approximately 5 and 80 degrees Celsius can be reached and precisely controlled.

[0014] In a further development of the invention, the sliding plates are designed and arranged so that a pressure of Obar to 5 bar can be applied to a plate-shaped product in the molding section.

[0015] Pressure devices designed as sliding plates are particularly suitable for achieving very uniform contact pressures in the mold section between 0 bar and 5 bar (0 N / m²). 2 up to 5 × 10 5 N / m 2) to achieve. The use of sliding plates as pressure devices is particularly advantageous for producing single-layer or multi-layer panels from materials with a thermoplastic binder, fiber-reinforced composite panels from fibers and thermoplastic polymer, or fiber-reinforced composite panels from fibers and a curing system, such as resin, PU, ​​or similar materials. In both cases, the fibers can be glass fibers, carbon fibers, or natural fibers. Significant advantages can be achieved in the production of laminates consisting of multiple layers of the same or different materials, as well as laminates consisting of a core and one or more face layers.

[0016] According to the invention, the double belt press is provided with a first, lower circumferential plastic belt and a second, upper circumferential plastic belt, wherein the plastic belts have a first, low bending stiffness and wherein a product gap is formed between the facing strands of the plastic belts for forming a plate-shaped product, wherein a first circumferential lower steel belt and a second circumferential upper steel belt are provided, wherein the steel belts have a second, high bending stiffness compared to the bending stiffness of the plastic belts, wherein a forming section is formed between the facing strands of the steel belts, the forming section forming part of the product gap.wherein in the molding section during operation the first lower steel strip runs parallel to and adjacent to a back side of the first plastic strip facing away from the product gap, and wherein in the molding section during operation the second upper steel strip runs parallel to and adjacent to a back side of the second plastic strip facing away from the product gap.

[0017] By incorporating steel bands forming a mold section, each bearing against the back of the plastic bands in sections, the advantages of a double-belt press with plastic bands and those of a double-belt press with steel bands can be combined surprisingly easily, without incurring their respective disadvantages. With the steel bands, significantly higher pressure can be exerted on the product gap and the pre-product within the mold section than would be possible with plastic bands. Specifically, the higher flexural stiffness of the steel bands allows for a much more uniform pressure distribution over a greater length of the mold section compared to plastic bands. The pre-product itself remains in contact exclusively with the plastic bands within the mold section, thus preventing any risk of it sticking to the steel bands.The double belt press according to the invention also offers advantages in terms of energy efficiency. A constant temperature can be maintained in the molding section throughout the entire process. Due to the high heat storage capacity of the steel belts compared to plastic belts, this is possible with minimal losses and even with heating devices not located directly in the molding area. The disadvantages that occur with pure steel belt presses, due to the required cooling of the steel belt in different sections of a product gap, do not occur with the double belt press according to the invention, since the steel belts only form part of the product gap in the molding section. Cooling of the product in the product gap can then take place, for example, downstream of the molding section between the plastic belts.Due to the poor thermal conductivity of plastic, the heat losses of the double belt press according to the invention are considerably lower than those of pure steel belt presses. This allows the double belt press according to the invention to easily produce very thick, sheet-like products, as well as to form semi-finished products into sheet-like products that require high contact pressure in the product gap. Nevertheless, the double belt press according to the invention is cost-effective compared to pure steel belt presses, since the steel belts are only required in the forming section and can be operated just as easily with regard to the manufacturing process of the sheet-like product as conventional double belt presses with plastic belts. According to the invention, heating and / or cooling devices are further provided for heating or cooling the first and second plastic belts outside the forming section.For example, the plastic belt can be heated in the feed area and also in a portion of the product gap upstream of the mold section. Downstream of the mold section, the plastic belts can then be easily cooled. Energy losses are minimal because the plastic belts, due to their low heat storage capacity, retain and transfer little heat energy along the product gap. This allows the sheet-shaped product to be pre-formed even outside the mold section containing the steel belts.

[0018] In a further development of the invention, heating and / or cooling devices are provided for heating or cooling the first and second steel strip.

[0019] By heating and / or cooling the steel strip, the mold section, as part of the product gap, can easily be kept at a nearly constant temperature. This is because the high heat storage capacity of the steel strips enables a uniform temperature along the entire length of the mold section.

[0020] In a further development of the invention, pressure devices are provided to apply a pressure to a product arranged between the plastic bands in the mold section by means of the steel bands.

[0021] In addition to sliding plates, such pressure devices can include, for example, roller chains running on the reverse side of the respective steel strip, pressure rollers, pressure plates, or similar components. Proven pressure devices already familiar from steel strip presses can be used here. For example, if pressure rollers spaced longitudinally apart are used, a uniform pressure distribution can be achieved despite the essentially linear contact of the pressure rollers, due to the high bending stiffness of the steel strips. The pressure distribution is in any case significantly more uniform than when a plastic strip with low bending stiffness is pressed by several pressure rollers arranged one behind the other.

[0022] In a further development of the invention, the pressing devices are designed to apply a contact pressure that is essentially uniform over the entire mold section by means of the steel bands in the mold section.

[0023] Providing a so-called isobaric contact pressure in the mold section is easily achievable due to the higher bending stiffness of the steel strips and their generally greater mechanical strength compared to plastic strips. In a further development of the invention, the plastic strips are provided with a non-stick coating, at least on their side facing the product gap.

[0024] Such a non-stick coating can, for example, consist of Teflon and is suitably tailored to the type of sheet-shaped product being manufactured. By providing such a non-stick coating, the manufactured sheet-shaped product can easily detach from the plastic belts at the end of the product gap, and the sheet-shaped product can even be removed from the product gap when very hot. A non-stick coating can also be achieved, for example, by continuously spraying a liquid upstream of the product gap. A non-stick coating can also be designed as a so-called nanocoating, which significantly reduces the contact angle of the product being processed on the plastic belts.Such a nanocoating can, for example, create the so-called lotus effect, in which the contact angle between a product droplet and the plastic band reaches a very high value of approximately 160°. This corresponds to extremely low wettability. Contact angles of 90° or more are preferred. The contact angle between the edge of a product droplet and the surface on which the droplet rests is also referred to as the contact angle or wetting angle.

[0025] In a further development of the invention, the machine frame of the double belt press has a modular design and, viewed in the longitudinal direction of the product gap, is formed from several modules that are detachably connected to one another. Advantageously, the two circumferential steel belts and deflections for the steel belts are arranged within a module section of the machine frame.

[0026] A modular design allows for the creation of double belt presses of varying lengths and configurations with minimal additional engineering effort, each specifically tailored to the production of a sheet-shaped product. Converting the double belt press to a different product is also significantly simplified. The arrangement of the two circulating steel belts within a single module, along with the optional integration of heating elements and pressure rollers within this module section, enables the retrofitting of a double belt press with circulating steel belts to the inventive double belt press. The heating elements within the module itself can be specifically adapted to the requirements of the circulating steel belts.

[0027] The following steps can be provided when manufacturing a sheet-shaped product with a double belt press: applying at least one pre-product in a feed area onto a first plastic belt, preheating the pre-product using infrared emitters, inserting the at least one pre-product into a product gap between the first and the second plastic belt, tempering and / or compressing the at least one pre-product in the product gap, inserting the at least one pre-product into a mold section, wherein the mold section forms part of the product gap, and tempering and / or compressing the at least one pre-product in the mold section using two steel belts that bear against the back of the plastic belts facing away from the product gap in the mold section.

[0028] Tempering and / or compressing at least one pre-product in the mold section using two steel bands allows for the production of very thick, sheet-like products, as well as sheet-like products made from pre-products that require comparatively high pressure during manufacturing. These could be, for example, sheet-like products containing natural fibers or those that otherwise require somewhat higher pressure to bond individual particles of the pre-products into a homogeneous mass. Even if no increased pressure is to be applied in the mold section, the steel bands allow for a simple and uniform heat flow into the pre-product along the length of the mold section. Due to the high heat storage capacity of steel bands, a uniform temperature distribution across the mold section can be achieved with simple means.In contrast to the use of double-belt presses with continuous steel belts running the entire length, heat losses are significantly reduced because the steel belts can remain at a constant temperature along the entire length of the forming section and do not need to be heated and then cooled in different sections. The application, in particular the sprinkling, of at least one thermoplastic pre-product in the feed area can be provided. Advantageously, the pre-product is heated in the feed area and / or in the product gap to achieve welding of particles of the at least one thermoplastic pre-product to one another.

[0029] Tempering and / or compression of at least one pre-product in the product gap outside the mold area may be provided.

[0030] It may be possible to laminate at least one layer into the product gap.

[0031] Decorative layers, thin films, or similar materials can be laminated onto the product to protect it from environmental influences. The films or layers are applied, for example, by means of unwinding devices mounted above the advanced lower belt of the double-belt press, or inserted into the product gap. Lamination is easily carried out using the inventive method and can even make difficult-to-process sticky products processable, since direct contact between the product and the plastic belts is no longer necessary.

[0032] Further features and advantages of the invention will become apparent from the claims and the following description of preferred embodiments of the invention in conjunction with the drawings. Individual features of the different embodiments shown in the figures can be combined with one another in any way without exceeding the scope of the invention. The drawings show: Fig. 1 a schematic representation of a double belt press according to the invention, Fig. 2 a sectional view of a double belt press according to a further embodiment of the invention and Fig. 3 a schematic representation of a double belt press according to the invention in a further embodiment.

[0033] The schematic representation of a double belt press 10 according to the invention in Fig. Figure 1 shows a first, lower circumferential plastic belt 12 and a second, upper circumferential plastic belt 14. An upper run of the first plastic belt 12 defines a feed area 16 in which a pre-product, for example, a thermoplastic pre-product, can be applied to the lower plastic belt 12. Above this feed area 16, a spreading device 18 is arranged, which essentially consists of a hopper for feeding the pre-product or several components in the form of granules or fibers. At the outlet of the hopper, a spreading roller 20 is provided, which extends over the entire width of the lower plastic belt 12. The spreading roller 20 is provided with bristles on its circumference to ensure uniform removal of the pre-product, which is in granular form, from the hopper 18 and to then spread this pre-product in a uniform layer thickness onto the lower plastic belt 12.

[0034] Downstream of the spreading device 18, a first heating device 22 is provided, which can, for example, heat the spread pre-product by means of infrared radiation.

[0035] Downstream of the feed area 16, a product gap 24 extends over a product gap section 25 from a front deflection roller 26 for the upper plastic belt 14 to a rear deflection roller 28 for the upper plastic belt 14. A rear deflection roller 30 for the lower plastic belt 12 is located directly opposite the rear deflection roller 28. Across the entire area of ​​the product gap 24, the plastic belts 12 and 14 are guided exactly parallel to each other by suitable guide rollers. Four pressure or guide rollers 32 are shown here by way of example only. The pressure rollers 32, and possibly other rollers, prevent the plastic belts 12 and 14 from moving too far apart when a pre-product is present in the product gap 24.If there is no pre-product in the product gap 24, the upper plastic band 14 rests on the lower plastic band 12 over large sections of the product gap 24 due to its comparatively low tension and low bending stiffness.

[0036] The two plastic belts 12, 14 rotate at exactly the same speed during operation of the double belt press 10. Therefore, there is no relative speed between a semi-finished product at the beginning of the product gap 24 or a plate-shaped product at the end of the product gap 24 and the plastic belts 12, 14.

[0037] In the initial section of the product gap 24, pressure and heating devices 34 are provided on the reverse side of the lower plastic belt 12 and on the reverse side of the upper plastic belt 14. These pressure and heating devices 34 maintain the height of the product gap at a precisely specified value and simultaneously heat the plastic belts 12 and 14, and thus also the pre-product located in the product gap. The illustrated double belt press 10 is designed for processing thermoplastic materials, and the heating by means of the pressure and heating devices 34 causes the individual particles of the pre-product in the product gap 24 to weld together. The pressure prevailing in the product gap in the area of ​​the pressure and heating devices 34 is comparatively low, on the order of 0.2 to 2 bar.At higher contact pressures, either the plastic bands 12, 14 wear out very quickly and / or undesirable surface structures form in the finished plate-shaped product, since the plastic bands 12, 14 are unable to distribute a locally applied pressure over a large area due to their low flexural stiffness.

[0038] Downstream of the pressing and heating devices 34, a first, lower circumferential steel band 36 and a second, upper circumferential steel band 38 are provided. The two circumferential steel bands 36, 38 are arranged such that the upper run of the lower steel band 36 rests against a rear side of the lower plastic band 12 facing away from the product gap 24. The upper steel band 38 is arranged such that its lower run rests against a rear side of the upper plastic band 14 opposite the product gap 24. By means of the two circumferential steel bands 36, 38, a contact pressure can be exerted on the plastic bands 12, 14 and thus on the product located in the product gap 24 within a mold section 40, which forms part of the product gap 24. This contact pressure is uniform over the entire length of the mold section 40, since the steel bands 36, 38 have a considerably higher bending stiffness compared to the plastic bands 12, 14.Furthermore, the upper run of the lower steel strip 36 and the lower run of the upper steel strip 38 are pressed against the product gap 24 by means of a circulating roller chain 42 and 44, respectively. The contact pressure in the product gap 24 within the mold section 40 is typically in the range of 10 bar to 20 bar. Such pressure is sufficient to form even difficult-to-process pre-products into sheet form and to achieve a sufficiently high density in the manufactured sheet products. For example, fibers, especially natural fibers, can be processed with thermoplastic filler material to form sheet products. The contact pressure in the mold section 40 is then sufficient to achieve a flat surface on the manufactured sheet product, even with a comparatively high stiffness of the fibers being processed.

[0039] Heating devices 46 are provided in the area of ​​the steel strips 36, 38, with the heating devices 46 acting on the lower run of the lower steel strip 36 or the upper run of the upper steel strip 38. Due to the comparatively high heat storage capacity of the steel strips 36, 38, the heating devices 46 can be arranged in the position shown and thus relatively far away from the product gap 24, since the steel strips 36, 38 can store sufficient heat. In addition to the heating devices 46, the respective front deflection rollers 48 and 50 for the steel strips 36, 38 can also be heated. For this purpose, fluid channels 52 can be provided in the interior of the deflection rollers 50 and 48.

[0040] The double belt press 10 according to the invention can readily be used in such a way that no or almost no contact pressure is exerted on the product gap 24 by means of the steel belts 36, 38, but rather the steel belts 36, 38 are merely held in their position to limit the product gap and thus the height of the manufactured plate-shaped product. In such a case, the steel belts 36, 38 are used only to introduce heat into the product gap 24.

[0041] Downstream of the mold section 40, further pressure or guide rollers 32 or, for example, further heating devices may be provided.

[0042] In the end region of the product gap 24, the illustrated double-belt press 10 is equipped with cooling devices in the form of spray nozzles 54, which spray cooling water against the underside of the upper run of the lower plastic belt 12. The reverse side of the upper plastic belt 14, facing away from the product gap 24, can be easily cooled, for example, by means of a blower 33. The finished, sheet-shaped product can then be removed from the end of the product gap 24.

[0043] The double belt press 10 also has features for laminating a coating. For this purpose, a roller 60 is provided before the product enters the product gap 24. A layer 62 to be laminated is wound onto this roller. This layer 62, for example a thin film, is then drawn into the product gap 24 together with the pre-product sprinkled in the feed area 16 and bonds with the pre-product during its passage through the product gap 24. It is, of course, also possible to laminate one or more layers onto both the underside and the top side of the sheet-shaped product.

[0044] The presentation of Fig. Figure 2 shows a double belt press 70 according to a further embodiment of the invention. The basic operating principle of the double belt press 70 is the same as shown in the Fig. The basic operating principle is described in section 1 and the double belt press 10, so no further explanation is necessary. The double belt press 70 has a feed area 72 in which a pre-product is applied to a lower plastic belt 74 by means of devices not shown, for example, spreading devices. Downstream of the feed area 72, a product gap area 76 begins, in which a product gap 78 has a constant height apart from an inlet and outlet area. After passing through the product gap 78, the manufactured sheet-shaped product can be removed at its end.

[0045] The machine frame of the double belt press 70 according to the invention has a modular design and consists of a total of eight modules 80 to 94. Each module 80 to 94 has a self-supporting, enclosed frame and is detachably connected to the other modules. Therefore, when assembling or modifying a double belt press 70 according to the invention, individual modules can be inserted or removed; only the length of the plastic belts 74, 75 needs to be adjusted.

[0046] Module 80 has a front deflection unit for the lower plastic belt 74. Heating devices are provided below the lower plastic belt 74 in the area of ​​module 82. Module 84 has a front deflection for the upper plastic belt 75 and heating devices below the lower plastic belt 74. Module 86 contains heating devices, specifically heating fans, to heat the lower plastic belt 74 and the upper plastic belt 75, and thus the pre-product located in the product gap 78, and to weld its particles together. Module 88 contains plate-shaped heating and pressure devices, as well as two pressure rollers 89 located centrally in the module 88, to adjust the height of the product in the product gap 78 to a predefined value.Module 90 includes a lower circumferential steel band 96 and an upper circumferential steel band 98, which run parallel to the product gap in the area of ​​a mold section 100 and bear against the respective rear sides of the plastic bands 74, 75 facing away from the product gap 78. In module 90, contact pressure can be exerted on the product located in the product gap 78 by means of the steel bands 96, 98, and / or heat can be introduced into the product gap 78, with the contact pressure typically being in the range between 10 and 20 bar. Module 92 again includes plate-shaped pressure and heating devices, and alternatively, cooling can also be performed in module 92. The rear deflection for the lower plastic band 74 and the upper plastic band 75 is located in module 94.

[0047] Based on the presentation of Fig. Figure 2 shows that the forming section 100, in which the two circumferential steel bands are provided, is significantly shorter than the length of the product gap 78. In this way, the double-belt press 70 according to the invention can be implemented cost-effectively, since the steel bands 96, 98 are expensive compared to the plastic bands 74, 75. Nevertheless, a comparatively high contact pressure can be exerted on the product located in the product gap 78 within the module 90, or a large amount of heat can be introduced. Due to the high bending stiffness of the steel bands 96, 98, a contact pressure with a uniform distribution can be exerted over the entire length of the forming section 100. The length of the forming section 100 is at most half the length of the product gap 78 and can even be less than one-tenth of the length of the product gap 78.

[0048] Fig.Figure 3 shows a double belt press 110 for continuous operation according to a further embodiment of the invention in a partially cut-away side view.

[0049] The double belt press has a lower plastic belt 112 and an upper plastic belt 114, both of which are made of Teflon (PTFE). Both the lower plastic belt 112 and the upper plastic belt 114 are continuous. A product gap 116 for producing a sheet-shaped product is defined between the upper run of the lower continuous plastic belt 112 and the lower run of the upper continuous plastic belt 114. The operation of the double belt press 110 is very similar to that of the double belt presses 10 and 70 already described. A winding device 140 is schematically indicated above the extended lower belt 112 before the start of the product gap 116. This device allows films or layers to be inserted into the product gap, for example, to produce a laminate.

[0050] The double belt press 110 has a first, lower steel belt 118 and a second, upper steel belt 120. The steel belts 120 and 118 have a high bending stiffness compared to the bending stiffness of the plastic belts 112 and 114. A forming section 100 is formed between the upper run of the circulating lower steel belt 118 and the lower run of the circulating upper steel belt 120. The forming section 100 forms part of the product gap. During operation, the upper run of the first, lower steel belt 118 runs parallel to and abuts the rear side of the upper run of the first plastic belt 112 in the forming section, facing away from the product gap 116. In the molding section, the lower run of the second, upper steel band 120 runs parallel to and adjacent to a rear side of the lower run of the second, upper plastic band 114 in the molding section 100, which faces away from the product gap 116.

[0051] In mold section 100, pressure devices are provided in the form of a first sliding plate module 122, a second sliding plate module 124, and a third sliding plate module 126. The first sliding plate module 122 has a first, lower sliding plate 128, which rests against the rear side of the upper run of the first, lower steel strip 118, facing away from the product gap 116. The first sliding plate module 122 has a second, upper sliding plate 130, which rests against the rear side of the lower run of the second, upper steel strip 120. The second sliding plate module 126 has a third, lower sliding plate 132 and a fourth, upper sliding plate 134. The third, lower sliding plate 132 rests against a rear side of the upper run of the first, lower steel band 118 facing away from the product gap 116, and the fourth, upper sliding plate 134 rests against a rear side of the lower run of the second, upper steel band 120 facing away from the product gap 116.The third sliding plate module 126 has a fifth, lower sliding plate 136 and a sixth, upper sliding plate 138. The fifth sliding plate 136 rests against the rear side of the upper run of the first, lower steel strip 118, facing away from the product gap, and the sixth, upper sliding plate rests against the rear side of the lower run of the second, upper steel strip 120, facing away from the product gap 116. By means of the sliding plates 128, 130, 132, 134, 136, 138, a very uniform contact pressure can be achieved on a plate-shaped product located in the product gap 116 in the mold section 100 or in the section of the product gap 116 located between the sliding plates 128, 130, 132, 134, 136, 138. Using the sliding plate modules 122, 124, 126, contact pressures between 0 bar and 5 bar can be achieved. Simultaneously, the sliding plates 128, 130, 132, 134, 136, 138 can be temperature-controlled to introduce heat into a plate-shaped product being manufactured in the product gap 116.

[0052] The sliding plates 128, 130, 132, 134, 136, and 138 each bear a sliding layer 142 against the respective rear side of the associated steel strip. Only the sliding layer 142 of the first sliding plate 128 is described here; the other sliding plates 130, 132, 134, 136, and 138 are similarly provided with a sliding layer. The sliding layer 142 is replaceable and consists, for example, of gray cast iron or graphite. Additionally, it may be provided that the respective rear side of the steel strip upstream of the sliding plates is coated with a lubricant, for example, oil, to further reduce the coefficient of friction between the sliding layer and the steel strip.

[0053] As explained, in the forming section 100, contact pressures in a low to medium pressure range of 0 bar to 5 bar can be achieved, making the double belt press 110 particularly suitable for the continuous production of sheet materials manufactured under such low to medium pressure. These can include, for example, single-layer or multi-layer sheets made of materials with a thermoplastic binder, fiber composite sheets made of a fiber (e.g., glass fiber, carbon fiber, natural fiber) and a thermoplastic polymer, fiber composite sheets made of a fiber (e.g., glass fiber, carbon fiber, natural fiber) and a curing system (e.g., resin, PU, ​​and similar materials), laminates consisting of several layers of the same or different materials, or laminates consisting of a core and one or more face sheets. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1 045 751 B1

[0002]

Claims

[1] Double belt press for continuous operation with a first circulating lower steel belt (36; 96) and a second circulating upper steel belt (38; 98), wherein an upper run of the first, lower steel belt is opposite a lower run of the second, upper steel belt and wherein a forming section is formed between the upper run of the first lower steel belt and the lower run of the second, upper steel belt for forming a plate-shaped product and wherein pressure devices are provided to apply a pressure in the forming section by means of the steel belts, with a first, lower circulating plastic belt (12; 74) and a second, upper circulating plastic belt (14; 75), wherein the plastic belts (12, 14; 74, 75) have a first, low bending stiffness, wherein a product gap (24; 78) is formed between the facing runs of the plastic belts (12, 14;74, 75) is formed for forming a plate-shaped product, wherein the steel strips (36, 38; 96, 98) have a second, high bending stiffness compared to the bending stiffness of the plastic strips (12, 14; 74, 75), wherein a forming section (40; 100) is formed between the facing sections of the steel strips (36, 38; 96, 98), wherein the forming section (40; 100) forms part of the product gap (24; 78), wherein in the forming section (40; 100) during operation the first, lower steel strip (36; 96) runs parallel to and abutting a rear side of the first plastic strip (12; 74) facing away from the product gap (24; 78), and wherein in the forming section (40; 100) during operation the second upper steel strip (38; 98) runs parallel to and running adjacent to a reverse side of the second plastic strip (14; 75) facing away from the product gap (24; 78), ; characterized bythat the pressure devices have sliding plates, wherein at least one first, lower sliding plate rests against a rear side of the upper run of the first, lower steel strip in the mold section and wherein at least one second sliding plate rests against a rear side of the lower run of the second, upper steel strip in the mold section. [2] Double belt press according to claim 1, characterized by that the sliding plates bear against the back sides of the steel strips with an area consisting of a sliding material, wherein the sliding material is cast iron or graphite. [3] Double belt press according to claim 2, characterized by that the area consisting of sliding material is designed as a replaceable sliding layer. [4] Double belt press according to one of the preceding claims, characterized by , that means are provided for applying lubricant to the reverse sides of the steel strips. [5] Double belt press according to one of the preceding claims, characterized by, that means are provided for tempering the sliding plates. [6] Double belt press according to one of the preceding claims, characterized by , that the sliding plates are designed and arranged so that a pressure of Obar to 5 bar can be applied to a plate-shaped product in the molding section. [7] Double belt press according to one of the preceding claims, characterized by , that heating and / or cooling devices (46, 52) are provided for heating or cooling the first and second steel strip (36, 38; 96, 98). [8] Double belt press according to claim 7, characterized by , that heating and / or cooling devices (34, 54) are provided for heating or cooling the first and second plastic strip (12, 14; 74, 75) outside the mold section (40; 100). [9] Double belt press according to one of the preceding claims, characterized by, that the sliding plates of the pressure devices (97, 99) are designed to apply a pressure that is essentially uniform over the entire mold area by means of the steel bands (96, 98). [10] Double belt press according to one of the preceding claims, characterized by , that the plastic bands (12, 14; 74, 75) are provided with a non-stick coating at least on their side facing the product gap (24, 78). [11] Double belt press according to one of the preceding claims characterized by , that a machine frame of the double belt press (70) has a modular structure and, viewed in the longitudinal direction of the product gap (78), is formed from several modules (80, 82, 84, 86, 88, 90, 92, 94) that can be detachably connected to one another. [12] Double belt press according to claim 11, characterized by, that the two circumferential steel bands (96, 98) and deflections for the steel bands (96, 98) are arranged within a module (90) of the machine frame.

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