Preparation method of reinforced PET (Polyethylene Terephthalate) material for wind power blade

Abstract

The invention relates to a preparation method of a reinforced PET material for a wind power blade, which comprises the following steps of: punching through holes and grooves in an integrally formed PET sandwich plate serving as a base material, inserting glass fiber yarns into the through holes, inserting glass fiber reinforced plastic sheets into the grooves, paving glass fiber fabrics on the upper and lower surfaces of the sandwich plate, and then performing vacuum glue pouring and curing, thereby obtaining the reinforced PET material for the wind power blade. And a reinforced PET material with a vertical glass fiber reinforced plastic column body, a glass fiber reinforced plastic fence and a glass fiber reinforced plastic large surface is formed. The PET core plate is used as a base body, the glass fiber reinforced plastic fence is used as a framework, the vertical glass fiber reinforced plastic columns play a stabilizing role, and the tensile resistance, compression resistance and shear resistance of the material are greatly improved through a composite material component with large glass fiber reinforced plastic faces on the upper portion and the lower portion, so that the composite material can completely replace Balsa wood to serve as a blade reinforcing material; therefore, a series of problems of unstable Balsa wood supply, large price fluctuation, difficult transportation, long growth cycle, uneven quality and the like can be solved, the leaf production quality can be guaranteed, the purchase cost can be reduced, and cost reduction and efficiency improvement are realized.

Description

Technical Field

[0001] The present invention relates to a preparation method of an enhanced PET material, and specifically to a preparation method of an enhanced PET material for wind turbine blades, belonging to the technical field of composite materials. Background Art

[0002] With the rapid development of the scale and technology of the domestic wind power industry, higher requirements are put forward for the supply stability and technical indicators of the materials required for wind power. The sandwich material of the wind turbine blade partly uses Balsa wood. Although it has advantages such as high strength and low density, it has many disadvantages, such as unstable supply, large price fluctuations, difficult transportation, long growth cycle, uneven quality, etc. Therefore, it is particularly important to develop a new type of sandwich material with excellent performance and controllable cost. The PET sandwich material is produced by using a determined formula and a fixed extruder, and it has advantages such as stable performance and convenient transportation. However, the overall performance of conventional PET is lower than that of Balsa wood. If PET is to be used to replace Balsa wood, its density still needs to be continuously increased to meet the requirements.

[0003] Currently, there are related technologies for improving composite materials, such as the utility model patent with the application number CN202020992724.X and the name "Z-direction enhanced protective composite material sandwich structure", the invention application with the application number CN201910966203.9 and the name "Processing method of a stepped hole type Z-direction enhanced core material", the invention application with the application number CN201210368665.9 and the name "Z-direction enhanced underwater sound absorption sandwich composite material and its preparation method", and the invention application with the application number CN200910060539.5 and the name "Composite material with an elastic core material sandwich structure and its preparation method". All of them improve the performance by punching and threading yarns in the Z direction of the core material. However, only the performance improvement in the Z direction is considered in the above-mentioned schemes, and the optimization in the transverse and longitudinal directions is not considered. Therefore, improvement is still needed. Summary of the Invention

[0004] Aiming at the problem that the current composite materials cannot replace Balsa wood for wind turbine blades, the present invention provides a preparation method of an enhanced PET material for wind turbine blades, which improves the strength of the PET material in all aspects and can resist the tensile, compressive and shear forces suffered during the operation of the blade.

[0005] The technical means adopted by the present invention to solve the above problems are as follows: A preparation method of reinforced PET material for wind turbine blades. Through holes are drilled and grooves are opened on the integrally formed PET sandwich board as the matrix material. Glass fiber yarns are inserted into the through holes. After inserting fiberglass sheets into the grooves, fiberglass cloth is laid on the upper and lower surfaces of the sandwich board, and then vacuum resin infusion and curing are carried out to form a reinforced PET material with vertical fiberglass columns, fiberglass grids, and fiberglass large surfaces. Using the integrally formed PET sandwich board as the matrix and the fiberglass grids as the framework, the vertical fiberglass columns play a stabilizing role.

[0006] Further, the grooves are arranged in a staggered manner along the transverse and longitudinal directions on one surface of the PET sandwich board, presenting a "well" - shaped structure, and multiple grooves evenly divide the surface of the PET sandwich board into multiple parts, with a through hole opened in the middle of each part. This makes the strength of each area of the PET sandwich board consistent and ensures the overall performance of the material.

[0007] Further, the height of the fiberglass sheet in the groove is the same as the depth of the groove.

[0008] Further, the depth of the groove is 70 - 95% of the thickness of the sandwich board.

[0009] Further, all the groove depths are the same.

[0010] Further, the distance between adjacent through holes is 10 - 40 mm.

[0011] Further, the through holes are round holes.

[0012] Further, the yarn inserted into the through holes is one or more of 600 - 1200 Tex E / TM2—468GS.

[0013] Further, the fiberglass sheets and fiberglass cloth in the grooves are one or more of E / TM2—1200 / 1380 / 1560.

[0014] Further, the fiberglass cloth is fixed on the upper and lower surfaces of the PET sandwich board after spraying glue.

[0015] Further, the curing process is as follows: Keep warm at 40°C for 4 - 5 h, increase the temperature from 40 - 50°C at a rate of 0.5°C / min, keep warm at 50°C for 2 h, increase the temperature from 50 - 75°C at a rate of 0.5°C / min, and keep the temperature constant at 75°C for 4 h.

[0016] The beneficial effects of the present invention are: 1. The present invention punches and grooves an integrally formed PET sandwich panel, threads yarns through the holes, and places fiberglass sheets in the grooves, forming a composite member with a PET core board as the matrix, a fiberglass grid as the skeleton, vertical fiberglass cylinders for stability, and large fiberglass surfaces on the top and bottom, thereby greatly enhancing the tensile resistance, compressive resistance, and shear resistance of the material.

[0017] 2. The present invention evenly arranges grooves in a "well" shape, divides the PET sandwich panel into multiple equal parts, and sets through holes in each part to thread yarns, ensuring that the strength of all regions of the entire composite material is consistent and the overall performance is higher, thereby facilitating the improvement of the durability of the material.

[0018] 3. The relatively deep grooves of the present invention can guide the resin, improve the preparation efficiency and fully infiltrate the material, and at the same time can insert relatively deep fiberglass sheets to ensure the strength of the grid. Description of the Drawings

[0019] Figure 1 Schematic three-dimensional diagram of the enhanced PET material for Example 1; Figure 2 Schematic diagram of the cube under the division of the fiberglass sheet for Example 1; Figure 3 Schematic diagram of the cylindrical glass fiber yarn for Example 1; Figure 4 Schematic diagram of the combination of the independent fiberglass sheet and the cylindrical glass fiber yarn for Example 1; Figure 5 Schematic diagram of the combination of the PET sandwich panel, the fiberglass sheet, and the cylindrical glass fiber yarn for Example 1; Figure 6 Schematic diagram of the PET sandwich panel with fiberglass cloth laid on the top and bottom surfaces without glue injection for Example 1. Detailed Embodiment

[0020] The present invention will be further described below in conjunction with the drawings. Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to this patent; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged, or reduced, which does not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. Example 1

[0021] A preparation method of an enhanced PET material for wind turbine blades, as Figures 1-6 shown, includes the following steps: Step 1: Place the integrally formed PET sandwich panel as the base material on a punching machine and a grooving machine to punch through holes (through-holes) and grooves (recesses). The distance between adjacent through-holes is 10 - 40 mm, and the depth of the recess is 70 - 95% of the thickness of the sandwich panel. The recesses are distributed alternately in the longitudinal and transverse directions, and the longitudinal recesses are all parallel to each other, and the transverse recesses are all parallel to each other. The surface of the panel is evenly divided into multiple cubes with the same size and a square bottom. There is a bundle of through-holes running through the upper and lower parts at the center of each cube. In this step, the PET sandwich panel used as the base is integrally formed by extrusion in the factory, and the product has better uniformity.

[0022] Step 2: Insert cylindrical fiberglass yarns into the above-mentioned through-holes, and insert fiberglass-reinforced plastic sheets with the same depth as the recesses into the above-mentioned recesses. The fiberglass-reinforced plastic sheets in the recesses form a fiberglass-reinforced plastic grid enclosure as the skeleton structure. Cooperating with the structurally stable cylindrical fiberglass yarns, it provides good support for the formed material.

[0023] Step 3: Cut two pieces of fiberglass cloth with the same size as the sandwich panel and cover them on the upper and lower surfaces of the sandwich. Before covering, use special spray glue for the production of wind turbine blades to fix them to prevent the fiberglass cloth from sliding. At the same time, it also restrains the yarns and fiberglass-reinforced plastic sheets in the holes and grooves to form a sandwich composite component.

[0024] Step 4: Vacuum-impregnate and cure the above-mentioned sandwich composite component. The specific curing process is as follows: keep warm at 40°C for 4 - 5 h, raise the temperature from 40 - 50°C at a rate of 0.5°C / min, keep warm at 50°C for 2 h, raise the temperature from 50 - 75°C at a rate of 0.5°C / min, and keep the temperature constant at 75°C for 4 h.

[0025] Step 5: Trim and shape the cured sandwich composite component, including local cutting, grinding, etc.

[0026] In the formed product, the structural adhesive is designed in the horizontal direction as the direction of the sandwich, and this direction is the weak direction in the sandwich test. However, the sandwich-fiberglass-reinforced plastic composite component of this product can provide sufficient support and compression resistance, so as to improve the mechanical properties of the sandwich.

[0027] The product performance will be tested and compared through specific examples below Specific Example 1 This specific example is basically the same as Example 1, except that: In Step 1, the distance between adjacent through-holes is 10 mm, and the depth of the recess is 80% of the thickness of the sandwich panel.

[0028] In Step 2, the fiberglass yarn inserted into the through-hole is 600 Tex E - 468GS, and the fiberglass-reinforced plastic sheet inserted into the recess is E - 1200.

[0029] In Step 4, keep warm at 40°C for 4 h.

[0030] Specific Example Two This specific example is basically the same as Example 1, except that: In the first step, the distance between adjacent through-holes is 10 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0031] In the second step, the fiberglass yarn passing through the through-holes is 800 Tex E-468GS, and the fiberglass reinforced plastic sheet inserted into the groove is E-1200.

[0032] In the fourth step, keep warm at 40 °C for 4 h.

[0033] Specific Example Three This specific example is basically the same as Example 1, except that: In the first step, the distance between adjacent through-holes is 10 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0034] In the second step, the fiberglass yarn passing through the through-holes is 1200 Tex E-468GS, and the fiberglass reinforced plastic sheet inserted into the groove is E-1200.

[0035] In the fourth step, keep warm at 40 °C for 4 h.

[0036] Specific Example Four This specific example is basically the same as Example 1, except that: In the first step, the distance between adjacent through-holes is 30 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0037] In the second step, the fiberglass yarn passing through the through-holes is 600 Tex E-468GS, and the fiberglass reinforced plastic sheet inserted into the groove is E-1200.

[0038] In the fourth step, keep warm at 40 °C for 4 h.

[0039] Specific Example Five This specific example is basically the same as Example 1, except that: In the first step, the distance between adjacent through-holes is 10 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0040] In the second step, the fiberglass yarn passing through the through-holes is 600 Tex TM2-468GS, and the fiberglass reinforced plastic sheet inserted into the groove is TM2-1200.

[0041] In the fourth step, keep warm at 40 °C for 4 h.

[0042] Specific Example Six This specific example is basically the same as Example 1, except that: In the first step, the distance between adjacent through-holes is 10 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0043] In the second step, the fiberglass yarn passing through the through holes is 1200 Tex TM2-468GS, and the fiberglass-reinforced plastic sheet inserted into the grooves is TM2-1200.

[0044] In the fourth step, keep the temperature at 40 °C for 4 h.

[0045] Comparative Example 1 This comparative example is basically the same as Example 1, the difference is: In the first step, the distance between adjacent through holes is 5 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0046] In the second step, the fiberglass yarn passing through the through holes is 600 Tex TM2-468GS, and the fiberglass-reinforced plastic sheet inserted into the grooves is TM2-1200.

[0047] In the fourth step, keep the temperature at 40 °C for 4 h.

[0048] Comparative Example 2 This comparative example is basically the same as Example 1, the difference is: In the first step, the distance between adjacent through holes is 10 mm, and the depth of the groove is 60% of the thickness of the sandwich panel.

[0049] In the second step, the fiberglass yarn passing through the through holes is 600 Tex TM2-468GS, and the fiberglass-reinforced plastic sheet inserted into the grooves is TM2-1200.

[0050] In the fourth step, keep the temperature at 40 °C for 4 h.

[0051] Comparative Example 3 This comparative example is basically the same as Example 1, the difference is: In the first step, the distance between adjacent through holes is 10 mm, and the depth of the groove is 80% of the thickness of the sandwich panel.

[0052] In the second step, the fiberglass yarn passing through the through holes is 600 Tex TM + -468GS, and the fiberglass-reinforced plastic sheet inserted into the grooves is TM + -1200.

[0053] In the fourth step, keep the temperature at 40 °C for 4 h.

[0054] Then, the formed sandwich-fiberglass composite components in the above examples are made into test specimens according to the tensile, compression, and shear test standard specimens, and their performance is tested together with the PET sandwich panel (sandwich body) after pouring glue and Balsa wood. The results are as follows:

[0055] Among them, the density of the PET sandwich panel: 200 g / m3 , Balsa wood body density: 170 g / m 3 (The mechanical properties of materials are directly related to their density).

[0056] As can be seen from the above table, the tensile, compressive, and shear resistance properties of the reinforced PET materials obtained from Specific Example 1 to Specific Example 6 are close to or even exceed those of Balsa wood, and are far higher than those of the sandwich body. Therefore, it can completely replace Balsa wood as the blade reinforcement material, thus solving a series of problems such as unstable Balsa wood supply, large price fluctuations, difficult transportation, long growth cycle, and uneven quality. It can not only ensure the quality of blade production but also reduce the procurement cost, achieving cost reduction and efficiency improvement.

[0057] However, the product properties obtained from Comparative Example 1 to Comparative Example 3 are lower than those of Balsa wood. It can be seen that the setting of grooves and through holes and the selection of materials also have a great impact on the product properties. Therefore, reasonable drilling, grooving, and material selection are also required to achieve the best effect.

[0058] The above embodiments are only for illustrating the present invention and not for limiting it. Those skilled in the relevant technical fields can make various changes or transformations without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also fall within the protection scope of the present invention, and the protection scope of the present invention should be defined by each claim.

Claims

1. A method for preparing a reinforced PET material for wind turbine blades, characterized in that: Through holes and grooves are made on the one-piece PET sandwich panel as the base material, glass fiber yarns are inserted into the through holes, and glass fiber reinforced plastic sheets are inserted into the grooves. Then, glass fiber cloths are laid on the upper and lower surfaces of the sandwich panel, and then vacuum glue is poured to form a reinforced PET material with vertical glass fiber reinforced plastic columns, glass fiber reinforced plastic fences and glass fiber reinforced plastic large surfaces.

2. The method for preparing the reinforced PET material for wind turbine blades according to claim 1, characterized in that: The grooves are arranged in a staggered manner in the horizontal and vertical directions on one surface of the PET sandwich plate, forming a "well"-shaped structure, and the plurality of grooves evenly divide the surface of the PET sandwich plate into multiple parts, with a through hole in the middle of each part.

3. The method for preparing the reinforced PET material for wind turbine blades according to claim 2, characterized in that: The height of the fiberglass sheet in the groove is the same as the depth of the groove.

4. The method for preparing the reinforced PET material for wind turbine blades according to claim 2, characterized in that: The groove depth is 70-95% of the sandwich panel thickness.

5. The method for preparing the reinforced PET material for wind turbine blades according to claim 2, characterized in that: All grooves are the same depth.

6. The method for preparing the reinforced PET material for wind turbine blades according to claim 2, characterized in that: The spacing between adjacent through holes is 10-40 mm.

7. The method for preparing the reinforced PET material for wind turbine blades according to claim 2, characterized in that: The through hole is a round hole.

8. The method for preparing the reinforced PET material for wind turbine blades according to claim 2, characterized in that: The yarns inserted in the through holes are one or more of 600-1200Tex E / TM2-468GS, and the glass fiber reinforced plastic sheets and glass fiber cloth in the grooves are one or more of E / TM2-1200 / 1380 / 1560.

9. The method for preparing the reinforced PET material for wind turbine blades according to claim 1, characterized in that: The glass fiber cloth is fixed on the upper and lower surfaces of the PET sandwich panel after being sprayed with glue.

10. The method for preparing the reinforced PET material for wind turbine blades according to claim 1, characterized in that: The curing process is: keep at 40℃ for 4-5h, heat up at 40-50℃ at a rate of 0.5℃ / min, keep at 50℃ for 2h, heat up at 50-75℃ at a rate of 0.5℃ / min, and keep at 75℃ for 4h.

Images