Process for producing polymeric leading edge protection sheets with beveled side edges

Abstract

Disclosed herein is a process for manufacturing polymeric leading edge protection sheets with chamfered side edges for wind turbine blades.

Description

[Technical Field]

[0001] Technical Field The present invention relates to a process for manufacturing polymeric leading edge protection sheets with chamfered side edges for wind turbine blades. [Background technology]

[0002] background For example, rotor blades of wind turbines, helicopters, and the like are exposed to a variety of environmental conditions, including erosion caused by the impact of airborne material such as rain, sand, dust, and other debris. The leading edges of wind turbine blades are particularly susceptible to erosion damage. Leading edge erosion is becoming more of a problem as rotor blades become longer, blade tip speeds increase, and wind turbines are constructed in more challenging and increasingly remote locations, including offshore sites.

[0003] The industry has sought to protect against such erosion using films and coatings, among other methods. In some instances, precast sections made of tough, yet soft and flexible, polymer shells are applied to the leading edges of wind turbine blades. The shells are designed and sized to absorb kinetic energy from rain, hail, and airborne particles. As such, the shells provide optimal protection for the blade's hard fiberglass surface.

[0004] In some instances, the film is applied to the leading edge of a wind turbine blade, where the film is applied around the leading edge of the wind turbine blade and adhered to the blade with an adhesive. The outermost surface of commercially available tapes is typically flat and, in its most basic configuration, includes a polymer film as a protective layer and an adhesive layer for attachment to the wind turbine blade. Some films have an overall contour of the outer upper surface of the film that is convexly curved or convex trapezoidal.

[0005] To form the outer top surface, a cutter is typically used to shape the surface after manufacture, however this results in an uneven outer surface on the film.

[0006] Therefore, there is a need for an improved process for manufacturing polymeric leading edge protection sheets for wind turbine blades that provides the sheets with improved outer surface smoothness. Summary of the Invention [Means for solving the problem]

[0007] overview In a first aspect, disclosed herein is a process for manufacturing a polymeric leading edge protection sheet with chamfered side edges for wind turbine blades, which refers to wind turbines of a wide range of sizes.

[0008] The process includes the following steps: providing a sheet of polymeric material having a first major surface and a second major surface, each major surface having a width extending widthwise between lateral edges of the sheet of polymeric material, the first major surface and the second major surface being oriented in opposite directions, and the sheet of polymeric material having a thickness; and - forming the polymeric material sheet into a polymeric leading edge protection sheet by providing the polymeric material sheet between at least one pair of rollers.

[0009] At least one pair of rollers comprises a first roller and a second roller; the first roller includes a first shaping surface extending between opposite ends of the first roller, the first shaping surface extending concavely between the opposite ends; the second roller includes a second shaping surface extending between opposite ends of the second roller; The first and second molding surfaces are disposed opposite each other; The thickness of the polymer material sheet is varied by the forming surfaces of the rollers during rotation of the first and second rollers to obtain a polymer leading edge protection sheet with chamfered side edges, the polymer leading edge protection sheet having a reduced thickness at the side edges compared to the sheet thickness in the central area.

[0010] A concavely extending first molding surface means that at least a portion of the middle section of the first roller has a smaller diameter than the end sections of the first roller. The roller may have a continuously decreasing diameter when measured from the side edges toward the center of the roller. Alternatively, the roller may have a continuously decreasing diameter when measured from the side edges toward a middle section that spans a particular width of the roller, e.g., 10% of the roller width.

[0011] By using at least one pair of rollers to modify and shape the polymeric leading edge protection sheet, it is possible to obtain a polymeric leading edge protection sheet with a specific surface profile by selecting the roller forming surface to suit the requirements.

[0012] This provides a much smoother surface profile on the polymeric leading edge protection sheet compared to a process in which a polymeric leading edge protection sheet having the same thickness is formed into a polymeric leading edge protection sheet with a chamfered edge by removing a portion of the polymeric leading edge protection sheet after production. The use of rollers ensures that the polymeric leading edge protection sheet accurately obtains the desired surface profile shape, as the polymeric leading edge protection sheet can be cooled during the process of providing the polymer material sheet between at least one pair of rollers. Furthermore, the above process provides an improved process for producing a polymeric leading edge protection sheet with improved smoothness of the outer surface due to the use of at least one pair of rollers.

[0013] The concavely extending first molding surface may be curved. Thus, in one or more examples, the first molding surface of the first roller is curved. Curved means that the surface deviates from a straight or planar surface without sharp interruptions or angles.

[0014] In a second aspect, disclosed herein is a polymeric leading edge protection sheet obtainable by the above process.

[0015] In a third aspect, disclosed herein is a wind turbine blade equipped with a polymeric leading edge protection sheet according to the above.

[0016] Providing a sheet of polymeric material can be achieved in a number of ways. One method is to melt a granular material and form it into a sheet of material. Thus, in one or more examples, the process further includes: - melting the granular polymer material by an extruder process to obtain a molten polymer material having a predetermined hardness, thereby obtaining a plasticized polymer material; - Forcing a plasticized polymeric material through a flat die to form the plasticized polymeric material into a polymeric material sheet.

[0017] After the plasticized polymeric material is forced through the flat die, the plasticized polymeric material can be pulled through rollers to form the plasticized polymeric material into a sheet of polymeric material.

[0018] In the extrusion process, granular polymer material (such as a thermoplastic polyurethane material) can be softened and melted by frictional heat generated using a screw or screw shaft that compresses the material by rotating within the extruder barrel. During the extrusion process, the granular polymer material is heated and the resulting plasticized polymer material is obtained at an elevated temperature. The plasticized polymer material can be maintained at an elevated temperature within the flat die by one or more electrical heating zones, which ensures that the plasticized polymer material remains in a moldable / plasticized state.

[0019] Prior to melting the granular polymer material, the granular polymer material may be dried to reduce or remove any moisture. Thus, in one or more examples, the process further includes providing a granular polymer material and drying the granular polymer material to a moisture level of 0.02 wt% or less prior to melting the granular polymer material. Drying may be performed, for example, by air drying in a desiccant air dryer.

[0020] In one or more examples, the polymeric material is a polyurethane material. The polyurethane material may be a polyurethane thermoplastic material. Thus, in one or more examples, the polymeric leading edge protective sheet is a polyurethane leading edge protective sheet. The polyurethane thermoplastic material may include a polyol, a chain extender, and an aliphatic isocyanate. The polyurethane leading edge protective sheet may be a thermoplastic polyurethane leading edge protective sheet. Polyurethane may be a polymeric material commonly used as the main material for polymeric leading edge protective sheets. However, alternative polymeric materials may also be used, including thermoplastic olefins, styrene block copolymers, thermoplastic copolyesters, silicone thermoplastics, silicone polyoxamides, aliphatic polyether-based thermoplastic polyurethanes, copolyester ethers, crosslinked polyurethanes, polyureas, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylenebutylene-styrene block copolymers (SEBS), and styrene-ethylene / propylene-styrene (SEPS) block copolymers. Any combination of polymeric materials may also be envisioned.

[0021] In one or more examples, the polymer material is a polyurethane material, and the granular polyurethane material is an aliphatic thermoplastic polyurethane (TPU) made from a polyol, such as a difunctional polyol, a butanediol chain extender, and an aliphatic isocyanate. "Difunctional polyol" means that the thermoplastic polyurethane polymer has two reactive groups per molecule. Typically, thermoplastic polyurethanes are linear. Aliphatic thermoplastic polyurethane (TPU) may be a commonly used granular polyurethane material. However, alternative granular polymer materials may also be used, including thermoplastic olefins, styrene block copolymers, thermoplastic copolyesters, silicone thermoplastics, silicone polyoxamides, aliphatic polyether-based thermoplastic polyurethanes, copolyester ethers, crosslinked polyurethanes, polyureas, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), styrene-butadiene-styrene block copolymers (SBS), styrene-ethylenebutylene-styrene block copolymers (SEBS), and styrene-ethylene / propylene-styrene (SEPS) block copolymer granules. Any combination of polymer granular materials may also be envisioned.

[0022] In one or more examples, the polymeric material is a polyurethane material, and the particulate polyurethane material further comprises one or more additives, such as a UV absorber, an antioxidant, and / or a pigment. The amount of additive can vary between 0.1 and 50 wt %. The additives can also include dyes, fillers, stabilizers, or combinations thereof.

[0023] In one or more examples, the polymeric material is a polyurethane material and the particulate polyurethane material does not include a release agent, which may be omitted to ensure a strong bond to the subsequent pressure-sensitive adhesive.

[0024] In one or more examples, the polymeric leading edge protection sheet is characterized by the following physical properties: - Maximum thickness of 0.8mm~2.0mm, - Shore A hardness between 65 and 75, as measured by ISO 868, - Elongation of more than 400 mm when measured at 23°C using ISO 37 / 1A, - sound speeds less than 1700 m / s, as measured according to ISO 16810 and ISO 16811, and - Erosion resistance of more than 8 hours at 150 m / s as measured by DNV-RP-0171.

[0025] In one or more examples, the polymeric leading edge protection sheet is characterized by the following physical properties: - Maximum thickness of 0.7mm~2.0mm, - Shore A hardness between 68 and 78, as measured by ISO 868; - Elongation of more than 400 mm when measured at 23°C using ISO 37 / 1A, - sound speeds less than 1700 m / s, as measured according to ISO 16810 and ISO 16811, and - Erosion resistance of more than 10 hours at 140 m / s as measured by DNV-RP-0171.

[0026] By maximum thickness, we mean the maximum thickness on the leading edge protection sheet. The maximum thickness is usually found in the center of the width of the polymer leading edge protection sheet. The thickness of the chamfered edge is always less than the maximum thickness of the polymer leading edge protection sheet. The maximum thickness usually depends on the hardness of the material. In many cases, if the material hardness is between 65 and 78, the maximum thickness should be less than 2 mm, perhaps less than 1.5 mm, or even less than 1.2 mm.

[0027] In one or more examples, the polymeric leading edge protection sheet has a minimum thickness of more than 0.01 mm, for example, more than 0.05 mm, for example, more than 0.10 mm. By minimum thickness, we mean the smallest thickness on the leading edge protection sheet. The smallest thickness is usually found at the chamfered edge of the polymeric leading edge protection sheet. The maximum thickness of the polymeric leading edge protection sheet is always greater than the smallest thickness of the chamfered edge. The minimum thickness usually depends on the hardness of the material.

[0028] In one or more examples, the polymeric leading edge protective sheet has a width in the width direction between the side edges of the polymeric leading edge protective sheet, the width including a first third and a second third, the first and second thirds being disposed adjacent to the respective side edges of the polymeric leading edge protective sheet, and the remaining third being disposed between the first and second thirds, and the change in thickness of the polymeric leading edge protective sheet in the width direction being greater in the first and second thirds than in the remaining third. The change in thickness of the polymeric leading edge protective sheet in the remaining third of the polymeric leading edge protective sheet corresponds to the change in thickness in the middle section of the polymeric leading edge protective sheet. If the polymeric leading edge protective sheet is substantially flat over a wider area around the middle section of the polymeric leading edge protective sheet, the change in thickness in the thirds may be close to zero. If the polymeric leading edge protective sheet has a thickness profile that varies continuously with a maximum in the middle area of ​​the polymeric leading edge protective sheet, the change in thickness in the remaining third will be greater than zero. However, this is typically less than the change in the first and second thirds of the polymeric leading edge protection sheet.

[0029] In one or more examples, the remaining third has a maximum thickness of less than 1.5 mm. Thus, the polymeric leading edge protection sheet may be characterized by a maximum thickness of between 0.7 mm and 1.5 mm, such as between 0.8 mm and 1.5 mm.

[0030] In one or more examples, the remaining third has a maximum thickness of less than 1.2 mm. Thus, the polymeric leading edge protection sheet may be characterized by a maximum thickness of between 0.7 mm and 1.5 mm, such as between 0.8 mm and 1.2 mm.

[0031] In one or more examples, the remaining third has a maximum thickness of less than 1 mm. Thus, the polymeric leading edge protection sheet may be characterized by a maximum thickness of between 0.7 mm and 1.5 mm, such as between 0.8 mm and 1.0 mm.

[0032] In one or more examples, the first third and second third have a minimum thickness of less than 0.5 mm. Thus, the difference in thickness of the polymeric leading edge protection sheet across the width of the sheet can be at least 1.5 mm, with the maximum thickness being between 0.7 mm and 1.5 mm, such as between 0.8 mm and 2.0 mm.

[0033] In one or more examples, the first third and second third have a minimum thickness of greater than 0.01 mm, such as greater than 0.05 mm, such as greater than 0.10 mm.

[0034] In one or more examples, the polymeric leading edge protective sheet has a width in the width direction between the side edges of the polymeric leading edge protective sheet, the width including a first quarter and a second quarter, the first and second quarters being disposed adjacent to the respective side edges of the polymeric leading edge protective sheet, and the remaining half being disposed between the first and second quarters, and the change in thickness of the polymeric leading edge protective sheet in the width direction being greater in the first and second quarters than in the remaining half. The change in thickness of the polymeric leading edge protective sheet in the remaining half of the polymeric leading edge protective sheet corresponds to the change in thickness in the middle section of the polymeric leading edge protective sheet. If the polymeric leading edge protective sheet is substantially flat over a wider area around the middle portion of the polymeric leading edge protective sheet, the change in thickness in the remaining half may be close to zero. If the polymeric leading edge protective sheet has a thickness profile that varies continuously with the thickness profile being maximum in the middle area of ​​the polymeric leading edge protective sheet, the change in thickness in the remaining half is greater than zero. However, this is typically less than the change in the first and second quarters of the polymeric leading edge protection sheet.

[0035] In one or more examples, the polymeric leading edge protection sheet has a Shore A hardness of 78 or less, as measured by ISO 868.

[0036] In one or more examples, the polymeric leading edge protection sheet has a Shore A hardness of 75 or less, as measured by ISO 868.

[0037] In one or more examples, the second shaping surface of the second roller extends cylindrically between the opposing ends. By cylindrical, we mean that the second roller has a diameter that does not vary or varies only slightly over the length of the roller. Alternatively, the second shaping surface may be slightly convex.

[0038] In one or more examples, the first and second rollers each have a longitudinal axis (LA1, LA2) extending between the opposite ends, and the longitudinal axes (LA1, LA2) are substantially parallel. Thus, the two rollers can be positioned opposite each other with an equal distance between the two ends of the rollers. In cases involving a polymeric leading edge protection sheet having a thinner side edge than the other, the distance between the first and second rollers can be slightly greater at one end of the rollers than at the other end of the rollers.

[0039] In one or more examples, the second molding surface of the second roller is smooth. The polymeric leading edge protection sheet typically has one flat surface and one curved surface. When the polymeric leading edge protection sheet is provided between the first pair of rollers, the first molding surface of the first roller typically contacts the curved surface of the polymeric leading edge protection sheet, and the second molding surface of the second roller typically contacts the flat surface of the polymeric leading edge protection sheet. After the polymeric leading edge protection sheet is manufactured as described above, an additional layer, such as an adhesive layer, may be added to the flat surface of the polymeric leading edge protection sheet. Having the second molding surface of the second roller smooth provides the polymeric leading edge protection sheet with a smooth, flat surface. When applying a pressure-sensitive adhesive to the flat side of the leading edge protection sheet after manufacturing, it is important to maximize the contact area, which is best achieved by having a smooth surface with low roughness on the flat surface of the polymeric leading edge protection sheet. If the second roller has a high degree of roughness, the pressure-sensitive adhesive (PSA) applied to the polymeric leading edge protective sheet after it leaves the roller may only adhere to the peaks on the surface of the polymeric leading edge protective sheet, and not come into contact with the valleys on the surface of the polymeric leading edge protective sheet, which means that the total contact area between the polymeric leading edge protective sheet and the PSA is less than 100%.

[0040] The extruded leading edge protection sheet can obtain its shape by forcing a hot, plasticized thermoplastic material through a flat die tool. The hot, plasticized preformed sheet can be pulled from the hot flat die over and through a first pair of rollers and cooled to define the final shape. Pulling can be accomplished by rotating the rollers.

[0041] Guiding the polymeric material sheet through the first pair of rollers and between the first pair of rollers, i.e., between the first roller and the second roller, can be achieved by pushing or pulling the polymeric material sheet. A combination of both pushing and pulling the sheet between the first pair of rollers can also be used. Thus, in one or more examples, forming the polymeric material sheet into a polymeric leading edge protection sheet is achieved by pulling and / or pushing the polymeric material sheet through at least one pair of rollers. The first roller can pull the polymeric material sheet through at least one pair of rollers.

[0042] Alternatively, the second roller may be the roller that pulls the polymeric material sheet through at least one pair of rollers. Further alternatively, both rollers of at least one pair of rollers may pull the polymeric material sheet through at least one pair of rollers. Thus, in one or more examples, forming the polymeric material sheet into a polymeric leading edge protection sheet is obtained by pulling the polymeric material sheet through at least one pair of rollers, and at least the first and / or second roller pull the polymeric material sheet through at least one pair of rollers.

[0043] In one or more examples, forming the polymeric material sheet into a polymeric leading edge protection sheet is achieved by forcing the polymeric material sheet through at least one pair of rollers, and at least one flat die / extruder forces the polymeric material sheet through at least one pair of rollers. The polymeric material sheet can be extruded from the flat die by one or more rotating screws. Once the polymeric material sheet enters the space between the first pair of rollers, the polymeric material sheet can be pulled through the rollers at the same speed as the rotating screws deliver more of the polymeric material sheet.

[0044] In one or more examples, forming the polymeric material sheet into a polymeric leading edge protection sheet is achieved by dropping the polymeric material sheet into a cavity between at least one pair of rollers, a process also known as using a coat hanger to obtain the shape of the polymeric leading edge protection sheet.

[0045] In one or more examples, the process further includes providing the polymeric leading edge protective sheet between a second pair of rollers, the second pair of rollers including a third roller and one of the first and second rollers. This allows the polymeric leading edge protective sheet to be guided first through the first pair of rollers and then through the second pair of rollers. Because the second pair of rollers share one of their rollers with the first pair of rollers, the polymeric leading edge protective sheet typically follows this roller as it rotates, thereby being guided through the roller of the second pair of rollers after exiting the space between the first pair of rollers. The third roller can be similar to the first or second roller in the sense that they have similar molding surfaces. Thus, in one example, the third roller includes a third molding surface extending between opposite ends of the third roller, the third molding surface extending concavely between the opposite ends. Alternatively, in one example, the third roller includes a third shaping surface extending between opposite ends of the third roller, the third shaping surface extending cylindrically between the opposite ends.

[0046] Alternatively, the second pair of rollers may include a third roller and a fourth roller, where neither the third roller nor the fourth roller is the first roller nor the second roller.

[0047] In one or more examples, the first, second, and / or third rollers are cooled. Cooling one or more of the rollers allows the polymeric leading edge protection sheet, which enters the first pair of rollers—and optionally the subsequent second pair of rollers—and has a high temperature that allows the side edges to be formed into a beveled polymeric leading edge protection sheet—to cool faster as it passes through the rollers. This may allow for improved control over obtaining a desired surface profile shape. Cooling can be achieved by using cooling water circulating inside one or more of the rollers. Alternatively, a different cooling liquid, such as glycol, may be used instead of cooling water.

[0048] The process may further include running the polymeric leading edge protection sheet through a quality control section to ensure performance / requirement specifications of the polymeric leading edge protection sheet, which is typically performed after exiting the pair of rollers.

[0049] The process may further include winding the polymeric leading edge protection sheet onto one or more rolls before adding the adhesive and / or shortening the polymeric leading edge protection sheet.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS Various examples will now be described with reference to the figures. Like reference numerals refer to like elements throughout. Thus, like elements will not be described in detail with respect to the description of each figure. It should also be noted that the figures are intended only to facilitate the description of the examples. They are not intended as an exhaustive description of the claimed invention, nor as a limitation on the scope of the claimed invention. Additionally, the illustrated examples need not have all aspects or advantages shown. An aspect or advantage described in connection with a particular example is not necessarily limited to that example and can be implemented in any other example, even if not so shown or explicitly described. [Brief explanation of the drawings]

[0051] [Figure 1] 1 shows a system for producing polymeric leading edge protection sheets with beveled side edges. [Figure 2] 1 shows a schematic of a process for manufacturing a polymeric leading edge protection sheet with beveled side edges. [Figure 3] 1 shows a perspective view of a flat die. [Figure 4A] 1 shows a side view of a system with a flat die and roller system. [Figure 4B] 1 shows a side view of a system with a flat die and roller system. [Figure 4C] 1 shows a side view of a system with a flat die and roller system. [Figure 5A] A first pair of rollers is shown without a leading edge protection sheet between the rollers. [Figure 5B] Shown is a first pair of rollers with a leading edge protection sheet between them. [Figure 6A] 1 shows a first and second paired set of rollers. [Figure 6B] 1 shows a first and second paired set of rollers. [Figure 6C] 1 shows a first and second paired set of rollers. [Figure 7A] 1 shows an example of a leading edge protection sheet with chamfered side edges. [Figure 7B] 1 shows an example of a leading edge protection sheet with chamfered side edges. [Figure 7C] 1 shows an example of a leading edge protection sheet with chamfered side edges. [Figure 7D] 1 shows an example of a leading edge protection sheet with chamfered side edges. [Figure 8] 1 shows a system for producing polymeric leading edge protection sheets with beveled side edges. DETAILED DESCRIPTION OF THE INVENTION

[0052] Description of the example Illustrative examples will now be described more fully below with reference to the accompanying drawings. In this regard, the examples may have different forms and should not be construed as limited to the description set forth herein. Accordingly, the examples are described below by reference to the figures only to illustrate aspects. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. A phrase such as "at least one of," when following a list of elements, modifies the entire list of elements and does not modify each individual element of the list.

[0053] In the drawings, the thicknesses of various layers and areas are exaggerated for clarity and ease of depiction. When a layer, area, element, or plate is said to be "on" another layer, area, element, or plate, it can be directly on top of the other layer, area, element, or plate, or intervening layers, areas, elements, or plates can be present between them. Conversely, when a layer, area, element, or plate is said to be "directly on" another layer, area, element, or plate, there are no intervening layers, areas, elements, or plates between them. Furthermore, when a layer, area, element, or plate is said to be "below" another layer, area, element, or plate, it can be directly below the other layer, area, element, or plate, or intervening layers, areas, elements, or plates can be present between them. Conversely, when a layer, area, element, or plate is said to be "directly below" another layer, area, element, or plate, there are no intervening layers, areas, elements, or plates between them.

[0054] The spatially relative terms "below" or "bottom" and "upper" or "top," "below," "below of," "less," "above," etc. may be used herein to describe the relationship between one element or component and another element or component, as shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if a device shown in the figures is turned over, an element described as being on the "below" side of, or "below" or "below" another element, would then be oriented on the "upper" side of, or "above" another element. Thus, the descriptive terms "below" or "below" can encompass both "below" and "upper" orientations, depending on the particular orientation of the figure. Similarly, if a device is turned over in one of the figures, an element described as "below" or "below" would be oriented "above" the other element. Thus, the exemplary terms "below" or "below" can encompass both an orientation of above and below, and, as such, spatially relative terms can be interpreted differently depending on the orientation in which they are described.

[0055] Throughout this specification, when an element is said to be "connected" to another element, the element is either "directly connected" to the other element or "electrically connected" to the other element with one or more intervening elements between them.

[0056] The terminology used herein is for the purpose of describing particular examples only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural, including "at least one," unless the context clearly indicates otherwise. "At least one" is not to be construed as limiting "a" or "an." It will be further understood that the terms "comprises," "comprising," "includes," and / or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0057] Terms such as "first," "second," and "third" may be used herein to describe various elements, but it will be understood that these elements should not be limited by these terms. These terms are used solely to distinguish one element from another. Thus, a "first element" described below can be referred to as a "second element" or a "third element," and "second element" and "third element" can be similarly referred to without departing from the teachings of this specification.

[0058] "About" or "approximately," as used herein, means within an acceptable range of deviation for a particular value, inclusive of the stated value, and taking into account the subject's measurements and the error associated with measuring the particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value.

[0059] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. Furthermore, terms such as those defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art, and will not be interpreted in an idealized or overly formal sense unless expressly defined as such in this specification.

[0060] Illustrative examples are described herein with reference to cross-sectional views that are schematic illustrations of idealized examples, with like reference numerals referring to like elements throughout. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Accordingly, the examples described herein should not be construed as limited to regions of specific shapes as shown herein, which may include deviations in shape resulting, for example, from manufacturing. For example, a region illustrated or described as flat may have rough and / or nonlinear features. Furthermore, sharp angles shown may be rounded. Accordingly, regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims. Some portions not relevant to the description may not be provided to specifically describe illustrative examples of the present disclosure.

[0061] Figure 1 shows a system for producing a polymeric leading edge protection sheet 120 having a chamfered side edge 122, and Figure 2 shows a schematic diagram of a process for producing a polymeric leading edge protection sheet using the system of Figure 1. The system shown in Figure 1 includes an extrusion system 10, a screen system 20, a flat die 50, a roller system 60, a conveyor 70, a quality control section 80, and a pull roll unit 90.

[0062] When manufacturing the polymeric leading edge protection sheet 120, a polymeric material sheet 106 is provided and formed into the polymeric leading edge protection sheet 120 by providing the polymeric material sheet 106 between at least one pair of rollers of the roller system 60 (206).

[0063] The polymeric material sheet 106 can be obtained in a number of different ways, for example, by melting 202 the granular polymeric material 100 in an extrusion process in an extrusion system 10 to obtain a molten polymeric material 102 having a predetermined hardness to obtain a plasticized polymeric material 104, and then forcing 204 the plasticized polymeric material 104 through a flat die 50 to form the plasticized polymeric material 104 into a polymeric material sheet 106, as shown in Figures 1 and 2. In the extrusion process, the granular polymeric material 100 can be softened and melted by frictional heat generated by the compression and rotation of a worm or worm shaft within an extruder cylinder. The granular polymeric material can be dried to a moisture level of 0.02 wt% or less, for example, by air drying in an air dryer, before melting 202 the granular polymeric material 100.

[0064] Forming the polymeric material sheet 106 into the polymeric leading edge protection sheet 120 can be achieved by pulling and / or pushing the polymeric material sheet 106 through at least one pair of rollers 610, 620, as shown in Figure 3. When pulling the polymeric material sheet 106 through at least one pair of rollers 610, 620, at least the first roller 610 and / or the second roller 620 pull the polymeric material sheet 106 through at least one pair of rollers 610, 620.

[0065] After the polymeric leading edge protection sheet 120 is obtained, it may be directed (208) via conveyor 70 through quality control section 80, which ensures performance / requirement specifications for the polymeric leading edge protection sheet 120. The polymeric leading edge protection sheet 120 may then be wound (210) onto one or more rolls 90 before adding adhesive and / or shortening the polymeric leading edge protection sheet 120. The polymeric leading edge protection sheet 120 may be cut into smaller pieces.

[0066] Figure 3 shows a portion of the flat die 50 in a perspective view. In Figures 4A-4C, the flat die is shown in side view with three different roller systems 60. The flat die 50 comprises an inlet channel 502 through which the plasticized polymer material 104 is directed via a side surface 504 onto a flat outlet channel 506. The polymer material sheet 106 exits the flat die 50 at an outlet edge 508 of the flat outlet channel. The plasticized polymer material 104 is maintained at an elevated temperature within the flat die 50 by an electrical heating zone 510, which ensures that the plasticized material remains in a moldable / plasticized state.

[0067] The roller system 60 shown in FIG. 4A includes several rollers 610, 620, and 630 arranged in pairs. The roller pairs include a first pair 61 of rollers including a first roller 610 and a second roller 620, and are arranged so that the polymer material sheet 106 exiting the flat die 50 first passes between these rollers before passing between the second pair 62 of rollers. Typically, the warm polymer material sheet 106 exiting the flat die 50 is cooled when it comes into contact with the rollers. The second pair 62 of rollers includes a second roller 620 and a third roller 630. The first roller 610 and the third roller 630 rotate in the same direction, while the second roller 620 rotates in the opposite direction to the first roller 610 and the third roller 630. The first major surface 108 of the polymeric material sheet 106 contacts the first roller 610, and the second major surface 110 contacts the second roller 620. The surfaces of the first roller 610 and the second roller 620 generally define the shape of the polymeric leading edge protection sheet 120 that exits the space between the two rollers 610, 620.

[0068] Compared to the roller system 60 shown in FIG. 4A, the roller system 60 shown in FIG. 4B has one fewer roller, i.e., only one roller pair 61 including a first roller 610 and a second roller 620. Compared to the roller system 60 in FIG. 4B, the roller system 60 in FIG. 4C has two roller pairs 61, 62. The first pair of rollers 61 including the first roller 610 and the second roller 620 are arranged so that the polymer material sheet 106 exiting the flat die 50 first passes between these rollers and then passes between the second pair of rollers 62. The second pair of rollers 62 includes a third roller 630 and a fourth roller 640. The first roller 610 and the third roller 630 rotate in the same direction, while the second roller 620 and the fourth roller 640 rotate in the opposite direction to the first roller 610 and the third roller 630. The two pairs of rollers 61, 62 are arranged in parallel. Therefore, compared to the roller system 60 of FIG. 4A, the same roller is not shared between the two pairs of rollers 61, 62.

[0069] The rollers 610, 620, 630, 640 shown in Figures 4A-4C are shown as viewed from one of the ends 614, 624, 634, 644 of each roller 610, 620, 630, 640 extending therebetween.

[0070] FIG. 5A shows a first pair of rollers 61, comprising a first roller 610 and a second roller 620. The first roller 610 has a first forming surface 612 that extends concavely between opposite ends 614 of the first roller 610. By first roller 610, we mean that the central section 616 of the first roller 610 has a smaller diameter than the end sections 618 of the first roller 610. This can also be seen in the figure, where the concave shape is clearly observed. The first forming surface 612 may be curved, as shown in the figure, where curved means that the surface deviates from a straight line or plane without sharp interruptions or angles. The length of the first roller 610 is shown as a first length LA1 extending through the center of the first roller 610.

[0071] The second roller 620 includes a second shaping surface 622 that extends between opposite ends 624 of the second roller 620. The second shaping surface 622 typically extends cylindrically between the opposite ends 624. By cylindrical, it is meant that the second roller 620 has a diameter that does not vary, or that varies only slightly, along the second length LA2 of the second roller 620. Alternatively, the second shaping surface 622 may be slightly convex.

[0072] As shown in Figure 5A, the first and second forming surfaces 612, 622 are positioned opposite each other. The polymeric material sheet 106 passes through the space between the first forming surface 612 and the second forming surface 622, as shown in Figure 5B, to obtain a polymeric leading edge protection sheet 120 having chamfered side edges 122 defined by the first forming surface 612 extending concavely between the opposite ends 614 of the first roller 610. This gives the polymeric leading edge protection sheet 120 a reduced thickness at the side edges 122 compared to the sheet thickness in the central area 124.

[0073] 6A-6C show three rollers 610, 620, 630 arranged as a first set of rollers 61 and a second set of rollers 62. Similarly as shown in FIG. 5A, the first set of rollers 61 includes a first roller 610 and a second roller 620. The second set of rollers 62, shown in FIGS. 6A-6B, includes a second roller 620 as shown in FIG. 5A and a third roller 630. The third roller 630 includes a third shaping surface 632 extending between opposite ends 634 of the third roller 630. The second and third shaping surfaces 622, 632 are positioned opposite one another.

[0074] The third shaping surface 632 on the third roller 630 shown in Figure 6A extends cylindrically between opposite ends 634. Alternatively, the third shaping surface 632 may be slightly convex. The third shaping surface 632 on the third roller 630 shown in Figure 6B extends concavely between opposite ends 634 of the third roller 630.

[0075] The second set of rollers 62 shown in Figure 6C includes a first roller 610 as shown in Figure 5A and a third roller 630. The third roller 630 includes a third molding surface 632 extending between opposite ends 634 of the third roller 630. The first and third molding surfaces 612, 632 are positioned opposite one another. The third molding surface 632 on the third roller 630 shown in Figure 6C extends cylindrically between the opposite ends 634. Alternatively, the third molding surface 632 may be slightly convex.

[0076] The polymeric material sheet 106 passes through the space between the first molding surface 612 and the second molding surface 622, as shown in Figures 6A-6C, to obtain a polymeric leading edge protection sheet 120 having chamfered side edges 122. The polymeric leading edge protection sheet 120 further passes through the space between the second molding surface 622 and the third molding surface 632, also as shown in Figures 6A-6C.

[0077] Typically, the forming surfaces 612, 622, 632 are smooth. When applying a pressure-sensitive adhesive to the leading edge protection sheet 120 after manufacture, it is important to have as high a contact area as possible. This can be achieved by having a low roughness, flat surface on the forming surfaces 612, 622, 632 of the rollers 610, 620, 630.

[0078] Like the other rollers 610, 620, 630, the fourth roller 640 shown in FIG. 4C includes a fourth molding surface (not shown) extending between opposite ends 644 of the fourth roller 640. In the example shown in FIG. 4C, the fourth molding surface is located opposite the third molding surface 632 on the third roller 630. The fourth molding surface may extend cylindrically between the opposite ends 644. Alternatively, the fourth molding surface may be slightly convex. Alternatively, the fourth molding surface may be concave. The shape of this molding surface depends on the shape of the third molding surface 632 positioned opposite.

[0079] Figures 7A-7D show different examples of leading edge protection sheets 120 with chamfered side edges 122. The leading edge protection sheets 120 have a width in the width direction W between the side edges 122 of the polymer leading edge protection sheet 120. The differences between the leading edge protection sheets 120 shown in Figures 7A-7D are the thickness T of the leading edge protection sheet 120 at the chamfered side edges 122 compared to the thickness in the central area 124, and the change in profile along the width W.

[0080] The width of the leading edge protection sheet 120 as shown in Figures 7A, 7C, and 7D includes a first third 131 and a second third 132, which are located proximate the respective side edges 122. A remaining third 133 is located between the first third 131 and second third 132. The thickness variation across the width of the polymeric leading edge protection sheet 120 is greater in the first and second thirds 131, 132, i.e., the side edges 122, than in the remaining third 133. This is most clearly seen in Figure 7D, where the thickness variation in the third third 133 is nearly zero.

[0081] The first third 131 and the second third 132 may have a minimum thickness of less than 0.5 mm, while the remaining third 133 may have a maximum thickness of less than 1 mm. The first third 131 and the second third 132 may have a minimum thickness of more than 0.01 mm, such as more than 0.05 mm, such as more than 0.10 mm.

[0082] 7B, the width of the leading edge protection sheet 120 comprises a first quarter 141 and a second quarter 142, which are located adjacent to the respective side edges 122. The remaining half 143 is located between the first quarter 141 and the second quarter 142. The thickness variation in the width direction of the polymer leading edge protection sheet 120 is greater in the first and second quarters 141, 142, i.e., at the side edges 122, than in the remaining half 143.

[0083] FIG. 8 shows an alternative system for producing a polymeric leading edge protection sheet 120 with chamfered side edges. The system shown in FIG. 8 includes an extrusion system 10, a flat die 50, a roller system 60, a conveyor 70, a quality control section 80, and a pull roll unit 90. The roller system 60 includes a first pair of rollers 61 including a first roller and a second roller 620. The roller system 60 also includes a second pair of rollers 62 including a second roller 620 and a third roller 630. The second pair of rollers 62 functions as a cooling roller. The second pair of rollers 62 is controlled by a control unit 64 and a cooling control unit 66 to control the cooling of the second pair of rollers 62. The quality control section 80 includes a thickness measurement unit 82 for measuring the thickness of the polymeric leading edge protection sheet 120. The system also includes a pulling station 84 for pulling the polymeric leading edge protection sheet 120 toward the pull roll unit 90. The pull roll unit 90 includes a tension control unit 92 for controlling the tension of the pull roll unit 90, and a pull roller 94. The functionality of the alternative system for producing a polymeric leading edge protection sheet 120 with chamfered side edges shown in Figure 8 is similar to that already described in Figure 1. [Explanation of symbols]

[0084] 10 Extrusion System 20 Screen System 50 Flat Die 60 Roller System 61 First pair of rollers 62 Second pair of rollers 64 Control unit for second pair of rollers 66 a cooling control unit for controlling the cooling of the second pair of rollers 70 Conveyor 80 Quality Control Section 82 Thickness measurement unit 84 Pulling Station 90 pull roll units 92 tension control unit for controlling the tension of the pull roll unit 94 Pullola 100 Granular polymer material 102 Molten polymer material 104 Plasticized Polymer Materials 106 Polymer material sheet 108 First principal surface 110 Second main surface 120 Polymer Leading Edge Protection Sheet 122 Chamfered side edges 124 Central Area 131 First Third 132 Second Third 133 The remaining third 141 First Quarter 142 Second Quarter 143 The other half 202 Melting the granular polymer material 100 in an extruder process 204. Forcing the plasticized polymer material 104 through the flat die 50 to form the plasticized polymer material 104 into a polymer material sheet 106. 206 Providing a polymeric material sheet 106 and forming it into a polymeric leading edge protection sheet 120 208 Guide the polymer leading edge protection sheet 120 through the quality control section 210 Winding the polymeric leading edge protection sheet 120 onto one or more rolls 502 Entrance Channel 504 Side 506 Flat Exit Channel 508 Flat outlet channel outlet edge 510 Electric heater 610 First Roller 612 First molding surface 614 End of first roller 616 Middle section of first roller 618 first roller end section 620 Second Roller 622 Second molding surface 624 End of second roller 630 The Third Roller 632 Third molding surface 634 End of third roller 640 The Fourth Roller 644 End of fourth roller LA1 First longitudinal axis length LA2 Second longitudinal axis length LA3 Third longitudinal axis length W1 First width W2 Second width RC Curvature Radius

Claims

1. 1. A process for manufacturing a polymeric leading edge protection sheet (120) having chamfered side edges (122) for a wind turbine blade, comprising: providing a sheet of polymeric material (106) having a first major surface (108) and a second major surface (110), each major surface (108, 110) having a width extending widthwise between lateral edges of the sheet of polymeric material (106), the first major surface (108) and the second major surface (110) being oriented in opposite directions, and the sheet of polymeric material (106) having a thickness; and forming (206) the polymeric material sheet (106) into a polymeric leading edge protection sheet (120) by providing the polymeric material sheet (106) between at least one pair of rollers comprising a first roller (610) and a second roller (620); the first roller (610) comprises a first shaping surface (612) extending between opposite ends (614) of the first roller (610), the first shaping surface (612) extending concavely between the opposite ends (614); the second roller (620) comprises a second shaping surface (622) extending between opposite ends (624) of the second roller (620); the first and second molding surfaces (612, 622) are disposed opposite one another; a process in which the thickness of the polymeric material sheet (106) is varied by the shaping surfaces (612, 622) of the rollers (610, 620) during rotation of the first and second rollers (610, 620) to obtain the polymeric leading edge protection sheet (120) with chamfered side edges (122), the polymeric leading edge protection sheet (120) having a reduced thickness at the side edges (122) when compared to the sheet thickness in a central area (124).

2. The process comprises: Melting (202) the granular polymer material (100) by an extruder process to obtain a molten polymer material (102) having a predetermined hardness, thereby obtaining a plasticized polymer material (104); forcing (204) said plasticized polymeric material (104) through a flat die (50) to form said plasticized polymeric material (104) into said polymeric material sheet (106); 10. The process of claim 1 further comprising:

3. 3. The process of claim 2, further comprising providing a granular polymer material (100) and drying the granular polymer material (100) to a moisture level of 0.02 wt% or less before melting the granular polymer material (100).

4. The process of any one of claims 1 to 3, wherein the polymeric material is a polyurethane thermoplastic material comprising a polyol, a chain extender and an aliphatic isocyanate.

5. The process of any one of claims 1 to 4, wherein the polymeric material is a polyurethane material and the polymeric leading edge protection sheet (120) is a polyurethane leading edge protection sheet.

6. 6. The process of any one of claims 2 to 5, wherein the polymeric material is a polyurethane material and the particulate polyurethane material is an aliphatic thermoplastic polyurethane (TPU) made from a polyol, such as a difunctional polyol, a butanediol chain extender, and an aliphatic isocyanate.

7. 7. The process of any one of claims 2 to 6, wherein the polymeric material is a polyurethane material and the granular polyurethane material further comprises one or more additives such as UV absorbers, antioxidants, and / or pigments.

8. The process of any one of claims 2 to 7, wherein the polymeric material is a polyurethane material and the particulate polyurethane material does not contain a release agent.

9. said polymeric leading edge protection sheet (120) having the following physical properties: a maximum thickness between 0.8 mm and 2.0 mm; a Shore A hardness between 65 and 75, as measured by ISO 868; Elongation of more than 400 mm when measured at 23°C using ISO 37 / 1A; A sound velocity of less than 1700 m / s as measured by ISO 16810 and ISO 16811, and Erosion resistance of more than 8 hours at 150 m / s as measured by DNV-RP-0171; The process according to any one of claims 1 to 8, characterized by:

10. said polymeric leading edge protection sheet (120) having the following physical properties: a maximum thickness between 0.7 mm and 2.0 mm; a Shore A hardness between 68 and 78, as measured by ISO 868; Elongation of more than 400 mm when measured at 23°C using ISO 37 / 1A; A sound velocity of less than 1700 m / s as measured by ISO 16810 and ISO 16811, and Erosion resistance of more than 10 hours at 140 m / s as measured by DNV-RP-0171; The process according to any one of claims 1 to 9, characterized by:

11. The process of any one of claims 1 to 10, wherein the polymeric leading edge protection sheet (120) has a Shore A hardness of 78 or less.

12. The process of any one of claims 1 to 11, wherein the polymeric leading edge protection sheet (120) has a Shore A hardness of 75 or less.

13. 13. The process of claim 1, wherein the polymeric leading edge protection sheet (120) has a width in a width direction between side edges (122) of the polymeric leading edge protection sheet (120), the width comprising a first third (131) and a second third (132), the first and second thirds (131, 132) being located proximate to the respective side edges (122) of the polymeric leading edge protection sheet (120), and a remaining third (133) being located between the first and second thirds (131, 132), and wherein a change in thickness in the width direction of the polymeric leading edge protection sheet (120) is greater in the first and second thirds (131, 132) than in the remaining third (133).

14. 14. The process of claim 13, wherein the remaining one-third (133) has a maximum thickness of less than 1 mm.

15. 15. The process according to claim 13 or 14, wherein the first third and the second third (131, 132) have a minimum thickness of less than 0.5 mm.

16. 16. The process of claim 1, wherein the polymeric leading edge protection sheet (120) has a width in a width direction between side edges (122) of the polymeric leading edge protection sheet (120), the width comprising a first quarter (141) and a second quarter (142), the first and second quarters (141, 142) being located proximate to the respective side edges (122) of the polymeric leading edge protection sheet (120), and a remaining half (143) being located between the first and second quarters (141, 142), and wherein a change in thickness in the width direction of the polymeric leading edge protection sheet (120) is greater in the first and second quarters (141, 142) than in the remaining half (143).

17. The process of any one of claims 1 to 16, wherein the second forming surface (622) of the second roller (620) extends cylindrically between the opposite ends (624).

18. 18. The process of any one of claims 1 to 17, wherein the first and second rollers (610, 620) each have a longitudinal axis (LA1, LA2) extending between the opposite ends (614, 624), and the longitudinal axes (LA1, LA2) are substantially parallel.

19. The process of any one of the preceding claims, wherein the first forming surface (612) of the first roller (610) is curved.

20. The process of any one of claims 1 to 19, wherein the second forming surface (622) of the second roller (620) is smooth.

21. 21. The process of any one of claims 1 to 20, wherein forming the polymeric material sheet (106) into the polymeric leading edge protection sheet (120) is obtained by pulling and / or pushing the polymeric material sheet (106) through at least one pair of rollers (610, 620).

22. 22. The process of any one of claims 1 to 21, wherein forming the polymeric material sheet (106) into the polymeric leading edge protection sheet (120) is obtained by pulling the polymeric material sheet (106) through at least one pair of rollers (610, 620), and at least the first and / or second rollers (610, 620) pull the polymeric material sheet (106) through at least one pair of rollers (610, 620).

23. 21. The process of any one of claims 1 to 20, wherein forming the polymeric material sheet (106) into the polymeric leading edge protection sheet (120) is obtained by dropping the polymeric material sheet (106) into a cavity between the at least one pair of rollers (610, 620).

24. 24. The process of any one of claims 1 to 23, further comprising providing the polymeric leading edge protection sheet (120) between a second pair of rollers, the second pair of rollers comprising a third roller (630) and one of the first roller (610) and the second roller (620).

25. 25. The process of claim 24, wherein the third roller (630) comprises a third shaping surface (632) extending between opposite ends (634) of the third roller (630), the third shaping surface (632) extending concavely between the opposite ends (634).

26. 25. The process of claim 24, wherein the third roller (630) comprises a third shaping surface (632) extending between opposite ends (634) of the third roller (630), the third shaping surface (632) extending cylindrically between the opposite ends (634).

27. The process of any one of claims 1 to 26, wherein the first, second and / or third rollers (610, 620, 630) are cooled.

28. 28. The process of any one of claims 1 to 27, further comprising providing the polymeric leading edge protection sheet (120) through a quality control section (80) that ensures performance / requirement specifications of the polymeric leading edge protection sheet (120).

29. 29. The process of any one of claims 1 to 28, further comprising winding the polymeric leading edge protection sheet (120) onto one or more rolls (90) before adding adhesive and / or before shortening the polymeric leading edge protection sheet (120).

30. A polymeric leading edge protection sheet (120) obtainable by the process according to any one of claims 1 to 29.

31. A wind turbine blade comprising a polymeric leading edge protection sheet (120) according to claim 30.

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