SI24502A - The manufacturing process of the models for windmill wings - Google Patents

Abstract

The present invention relates to the production of wind turbine windscreens for wind farms. The process involves 3D computer modeling of the designa model of the wing wing, preparation of the supporting structure and construction of the steel support base, the production of a wooden frame made of wood ribs, which are attached to the supporting structure and the position of each individual rib is precisely determined with respect to x, y, with the coordinates the rib covers with wooden plies to completely close the model, the wet lamination with layers of glass fibers, coated with an epoxy resin, with a layer of abrasive deposited on the top layer, dry lamination with an infusion, which involves the application of a layer of balsa and a layer of glass fibers coating with epoxy paste, temperature treatment of the model, coarse and fine milling of epoxy paste with CNC machine with positive compensation for achieving the final 3D surface with adequate accuracy, inspection and repair of surface defects, laser surface measurement, finishing and surface smoothing and vacuum test for determining or model in which place it leaves the air.

Description

The subject of the invention

The object of the invention is a method of manufacturing a model for a wing of a windmill, hereinafter referred to as a windmill, at wind farms. The mold is then made for mass production of windmills.

A technical problem

A central technical problem is how to technologically design a windmill model that would provide adequate accuracy with respect to computer 3D geometry. The tolerance tolerance is typically of the order of 0.5mm for models longer than 20m. The model must be designed in such a way that tolerance while using the model, i.e. when making a mold based on a model, it does not deteriorate. The materials and construction chosen must exhibit a sufficient degree of robustness, also due to the high tensile forces during transport and other manipulations, and at the same time be resistant to temperatures higher than 70 ° C. These temperatures are released by endothermic processes in the use of paste and resin in the design of the model.

The prior art

Until the introduction of computer 3D modeling, windmills of various shapes were used, and in particular, the windmills were cut off at right angles. Technologically, this design was easier to produce, but the final efficiency was therefore lower than modern models. Only the more expensive and heavier materials, such as wood and metal, were used to make the model of the windmill, which could not be machined with the precision required by modern technology.

With modern windmill models made possible by computer 3D modeling, it is possible to design such a windmill that optimizes the use of wind motion. The resulting pressure differentials and forces in this way can significantly increase the efficiency of the wind farm itself and thus more quickly justify the investment in the form of recovered electricity.

The solution to a technical problem

Said technical problem has been solved by the process of the invention. The model for the windmill is made in the following steps.

3D Computer Modeling: means the computer design of a design model based on a numerical calculation of the best efficiency for a final wind farm installed at a specific location. It begins in a construction where 3D geometries are computer-aided by theoretical simulations of wind conditions. The effective surface of the windmill, the auxiliary flanges and the position of the supporting structure are defined. For larger windmills longer than 20 m, the models are split into several smaller units, because logistical constraints, such as the maximum transport length and the physical limitations of tools such as a mill, stove and workshop, must be observed.

Construction of the load-bearing structure: The load-bearing structure must be rigid enough to withstand the curvature, both on its own weight and on the weight of the model itself. The total weights can vary between 3-6 t for smaller models and 6-12 t for larger models. The supporting structure consists of horizontal bars, vertical bars, diagonal reinforcements, mounting and leveling plates of the base, lifting arms and, optionally, side extensions. Hollow steel square or rectangular profiles of the following dimensions are used to construct the load-bearing structure: 100/100/3 (100 mm χ 100 mm χ 3 mm thickness), 60/60/3, 50/50/2, 100/60/3 and 100/50/3: for horizontals 100/60/3 or 100/50/3 for larger structures, for smaller and narrower ones 60/60/3, for verticals 60/60/3 for larger and 50/50/2 at smaller structures, for diagonal reinforcements 50/50/2. PL 50x200x12 mm aluminum plates with welded nut M20 are used for the mounting and leveling plates. The panels have holes Φ17 for mounting to the floor for a M20xl00 leveling screw with M16xl50 steel anchors.

From the point of view of precision of the final model, it is crucial that after each movement between the various phases and tools, the base is properly fixed to the ground and horizontally leveled, which is done with a laser.

Wooden frame construction: The wooden frame represents the first rough approximation to the final model and forms the basis for the paste application (fine model). The frame is made up of wood fins that are precisely cut on a cutting device based on a computer 3D model. The ribs are fixed to the supporting structure by screws. It is very important that the position of each individual rib is accurately determined with respect to x, y, from the coordinate, which is determined by the laser. The fins are eventually covered with wooden planks, thus completely closing the model. 22.5 mm thick QSB wood panels are used for the ribs for increased load capacity. Slightly thinner 15 mm QSB boards are used to cover the ribs. Appropriate adhesive is used for bonding.

Wet lamination: Two layers of fiberglass are first laid on the wooden frame and impregnated with an epoxy resin mixed with the hardener in an appropriate ratio. A layer of abrasive ("peel ply") is already applied to the top layer of fiberglass, which is simply torn off / removed after laminating or vacuuming, leaving a finely rough surface for further processing. The purpose of wet lamination is to make vacuum tight, that is, to prevent the passage of air from the wood frame through this layer. Vacuum leakage is required later in making the mold based on this model - the mold uses an infusion process that would not work if the model were not vacuum tight. After lamination, wait at least 12 hours before proceeding to the next phase.

Dry infusion lamination: The fiber layer from the previous phase is too thin to maintain surface stability according to the geometric model. Therefore, a 19.5 mm thick balsamic layer is embedded in the surface, covered with two layers of fiberglass, such as the EQX 2400, and all coated with resin mixed in the appropriate ratio with the hardener. The infusion resin is used for infusion. The model is prepared for infusion by distributing helical tubes over the upper (laminated) surface. Vacuum tubes are connected to the helical tubes at distances of lm to ensure resin flow. Vacuum-connected helical tubes also run along the side of the model, with the function of sucking air through a vacuum pump. For this purpose, the entire model is covered with a vacuum bag and sealed tightly to the model. When the pressure is created, the resin automatically penetrates the laid balsa and EQX fibers, thus creating a quality laminate. In the event that vacuum sealing is not properly performed, air pockets may appear in the laminate, which impair its mechanical properties. After infusion, wait at least 12 hours before proceeding to the next phase.

Paste Laying: The model goes numb before the start of this phase. The epoxy paste, which is actually a combination of the SC-175 epoxy resin and the SC-175 epoxy hardener in a 1: 1 ratio, is a material that can be very elegantly molded to precise dimensions. The paste is applied to the model by hand or machine with a CNC machine - depending on the geometry of the model itself. Typically, larger surfaces are machined, for greater speed and accuracy of application, and then the details and edges are then manually applied. In this working process, care must be taken when applying the paste, that there are no air bubbles, that the paste is not too large, and that there is always a proper relationship between the paste and the hardener. Wait at least 12 hours before further processing. The thickness of the layer is very important when applying the paste. Too low a thickness of less than 4mm can risk cutting through the paste in the next phase and damaging the laminate. Excessive thickness greater than 30mm causes the temperatures inside the paste to rise too high and damage the model. In addition, a thicker paste can also cost significantly more. An optimum thickness of 8 to 20 mm is used.

Temperature treatment: At this stage, the model is placed in a furnace and it is worn out. The oven has the possibility of programmatically setting the operating temperature. The model should be exposed to 80 ° C for 10 hours. During this time and at this temperature, all materials are properly cured and stabilized. When a mold is made based on the model, temperatures will rise to 60-70 ° C, so the model must be insensitive to these conditions. The temperature warming must be carried out gradually, in steps of 1 hour, raising the temperature to 10 ° C (the initial temperature is 20-30 ° C) until the maximum temperature of 80 ° C is reached, where the model is left for 10 hours. The cooling phase then follows - the model is exposed to a temperature of 30 ° C for 80 minutes. The automatic controlled oven has its own internal temperature sensor. It is installed on the model, along with two other sensors connected to the computer, which graphically monitor the furnace.

Milling: The model is placed underneath the milling cutter and is rotten. The CAM department prepares a 3D model for this tool. 3, 4 or 5 axis operations may be used to process the models. The model is milled with positive compensation. When creating programs, care must be taken to keep the tool away from the surface. The operator must pay attention to the movement of the machine and to the milling of the surface itself. The device defect must be lower than the tolerances required, for windmills below 0.5 mm. First, the paste is cut into rough. When this is completed, it is checked that the paste has not been applied too much and corrected. It can be repaired with an epoxy paste, or with an epoxy putty that has a faster drying time but is only used for minor imperfections. When the patches are properly dried, fine milling begins.

Surface repair: The model is put into a workshop and sweaty. After milling, cracks or indentations may occur on the model and need to be repaired with a suitable putty. The Avvlfair D8200 combined with the D7222 converter is usually used. At this stage, it is also checked that all markers are made.

Laser surface measurement: The surface of the model is laser-measured. The measurement is compared with the original 3D scheme and differences are identified. The tolerances may not exceed ± 0,5 mm. Minor deviations can be corrected in the finishing and smoothing stages. If differences are found, the model returns to the paste laying phase and the process is repeated until the faults have been corrected.

Finishing and smoothing the surfaces: the model is then sanded, first with coarse sanding paper of granulation 100. It is then coated (for this procedure we use Intertherm 228) and finally sanded to a fine sand with granulation paper 320.

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Vacuum test: This is the final and mandatory test to check that air is passing through the surface of the model. If this is the case, such holes must be repaired with a putty and sanded again. The vacuum test shall be carried out by covering the model with vacuum bags and sealing them side-by-side. The vacuum pump draws in air and records the initial pressure value at time t = 0. The pump is then left in operation for a further 20 minutes, during which time the pressure should not drop by more than 0.03 bar.

The method according to the invention is characterized in that it comprises: 3D computer modeling of the design of the wing wing model, preparation of the load-bearing structure and construction of the steel load-bearing base, production of a wooden frame from the wood ribs that attach to the load-bearing structure and the position of each individual rib is precisely determined with respect to the χ, γ, ζ coordinates and the ribs are covered with wooden boards to completely close the model, wet lamination with layers of fiberglass impregnated with epoxy resin, with a layer of abrasive applied on the top layer, dry lamination with infusion involving the application of a resin layer of balsa and fiberglass layers, using infusion resin, epoxy paste deposition, model temperature treatment, coarse and fine milling of epoxy paste with a CNC machine with positive compensation to achieve the final 3D surface with proper accuracy, inspection and repair of surface defects, laser surface measurement, completion and surface smoothing and a vacuum test to determine whether the model is leaking air.

Claims (1)

A process for making a model for a windmill wing, characterized in that it comprises: - 3D computer modeling of design of windmill wing model; - preparation of the load-bearing structure and construction of the steel load-bearing base; - making a wooden frame from wood fins that attach to the supporting structure and the position of each individual rib is determined with respect to x, y, from the coordinates and the ribs are covered with wooden boards to completely close the model; - wet lamination with layers of glass fiber, impregnated with epoxy resin, with a layer of abrasion applied to the top layer; - dry lamination by infusion, involving the application of a resin layer of balsa and fiberglass layers, using infusion for resin blending; - laying of epoxy paste; - temperature treatment of the model; - coarse and fine milling of the epoxy paste with a CNC machine with positive compensation to achieve the final 3D surface with adequate precision; - inspection and repair of surface defects; - laser surface measurement - finishing and smoothing the surface; - Vacuum test to determine whether the model is leaking air.