A method for controlling the gap between the root end face and flange of a pre-embedded blade mold

Abstract

The present invention discloses a method for controlling the gap between the root end face of a pre-embedded blade mold and a flange. In the initial stage of blade production, only an exhaust gap is reserved between the flange and the root end face of the mold. When the blade expands thermally, the flange is made to retreat backward while maintaining contact with the root end face of the blade to form an expansion gap between the flange and the root end face of the mold, thereby meeting the spatial requirement for the outward expansion of the root end face of the blade; the spacing of the exhaust gap is 0.1-0.3mm; the flange is made to retreat backward while maintaining contact with the root end face of the blade by using a bolt shank of a fixing bolt through a compression spring to press the flange, and the flange is retreated by applying a backward force F to the flange. Its advantages are: under the premise of avoiding glue overflow between the flange and the blade root end face of the mold, it ensures normal exhaust between the flange and the blade root end face of the mold, and can make the flange retreat when the poured molten glue expands due to heat to form an expansion gap between the flange and the blade root end face 1 of the mold, making room for the blade root end face of the blade to expand backward.

Description

Technical Field

[0001] The invention relates to a method for controlling the gap between a blade root end face and a flange of a pre-embedded blade mould, and belongs to the technical field of transformer testing. Background Art

[0002] Wind turbine blades are manufactured in a mold whose inner surface corresponds to the outer surface of a longitudinally sectioned half of the blade. A release layer is first applied to the mold's inner wall to prevent the glue from sticking to the inner wall of the shell. Fiber cloth is then laid and glue is applied, with each layer of cloth applied once. Once the desired thickness is achieved, the beam is placed, and glue is poured uniformly at a temperature above 70°C. Finally, the glue is cooled and hardened into shape. The two halves of the wind turbine blade are then secured together by closing the mold and then demolded, essentially completing the blade.

[0003] The root end of a wind turbine blade features a circle of bolt holes for mounting and fixing. Currently, these bolt holes are arranged in two ways: a punched structure and a pre-embedded bolt sleeve structure. The punched root is designed to be made of pure composite material, and after the blade is formed, drilling, nut installation, and nut hole sealing are performed. In the pre-embedded bolt sleeve structure, bolt sleeves are used instead of nuts, allowing the bolt sleeves and the root structure to be integrally formed. This eliminates the need for post-molding drilling and sealing, reduces equipment, tooling, and site investment, and results in a lower overall cost. Currently, most blades on the market use a pre-embedded bolt sleeve structure. Blades with this structure require a flange to be fixed to the root of the blade mold. Fixing bolts are then inserted through pre-machined holes in the flange to secure the bolt sleeves to the flange, ensuring that the blade root bolt sleeves are positioned correctly with the hub of the complete blade. Pre-embedded blades are blades in which an internally threaded bolt sleeve is pre-embedded at the root end during manufacturing.

[0004] As mentioned above, the production of pre-embedded blades involves the use of a flange, a stopper that restricts the blade's root end during production. To ensure a flat blade root, the flange should be placed as close to the mold's root end as possible. However, if the flange is too close to the mold's root end, air trapped in the angle between the mold's inner wall and the flange cannot escape during glue pouring, creating holes in the blade's root end, resulting in a substandard product. Furthermore, during high-temperature glue pouring, the blade undergoes thermal expansion, increasing the length of the root end by 1-3 mm. If blocked by the flange, this would result in a bulge at the root end that extends into the blade cavity, causing the fiber cloth to wrinkle and deform, severely impacting the blade's load-bearing structure. Preserving a 3mm thermal expansion gap between the flange and the mold's root end, while preserving both air escape and thermal expansion during glue pouring, would also result in serious glue leakage. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: how to achieve normal exhaust during glue pouring and normal expansion of the blade outward from the root end during thermal expansion, while ensuring that there is no glue leakage between the root end face of the embedded blade mold and the flange.

[0006] In view of the above problems, the technical solution proposed by the present invention is:

[0007] A method for controlling the gap between the root end face of a pre-embedded blade mold and the flange is to reserve only an exhaust gap between the flange and the root end face of the mold in the initial stage of blade production. When the blade expands thermally, the flange is made to retreat backward while maintaining contact with the root end face of the blade to form an expansion gap between the flange and the root end face of the mold, thereby meeting the space requirement for the root end face of the blade to expand outward.

[0008] The spacing of the exhaust gap is 0.1-0.3 mm.

[0009] The flange is made to retreat backward while maintaining contact with the root end surface of the blade by pressing the flange with the bolt shank of the fixing bolt through a compression spring, and applying a backward force F to the flange to cause the flange to retreat.

[0010] The backward force F applied to the flange includes utilizing the backward expansion pressure F1 applied by the root end of the blade to the flange when the blade expands thermally.

[0011] The backward force F applied to the flange also includes an external force F2.

[0012] A plurality of blind holes are axially arranged on the blade root end face of the mold, and a thermal expansion airbag is arranged in the blind hole. When the glue is poured, the heat of the melt causes the blade to expand and the thermal expansion airbag to expand at the same time. The external force F2 is the backward force applied to the flange by the thermal expansion airbag when it expands.

[0013] An elastic baffle is provided at the opening of the blind hole, which seals the thermal expansion bag in the blind hole, transfers the pressure of the thermal expansion bag to the flange, and relies on the tensile deformation of the elastic baffle to ensure that the thermal expansion bag expands and pushes the flange back.

[0014] The thermal expansion bag is placed at the inner end of the blind hole, and the piston body is set at the outer end of the blind hole. The expansion pressure of the thermal expansion bag when it expands is transmitted to the flange through the piston body.

[0015] A concave annular sinking platform is arranged on the periphery of the blind hole, and an annular pressing plate is added, and the outer periphery of the elastic baffle is fixedly pressed on the annular sinking platform by the pressing plate through countersunk screws.

[0016] The thickness of the annular pressing plate is set so that the annular pressing plate protrudes 0.1-0.3 mm from the blade root end face of the mold. The flange is pressed against the annular pressing plate to form an exhaust gap between the blade root end face of the mold and the flange. Beneficial effects

[0017] 1. Under the premise of avoiding glue overflow between the flange and the blade root end face of the mold, it ensures normal air discharge between the flange and the blade root end face of the mold, and when the poured molten glue expands due to heat, the flange can be retracted to form an expansion gap between the flange and the blade root end face 1 of the mold, making room for the blade root end face to expand backward;

[0018] 2. The flange retraction force is reasonable to ensure that the fiber cloth at the root end of the blade will not wrinkle or bulge due to excessive expansion resistance, so that the blade maintains the best mechanical structure;

[0019] 3. Simple structure and easy operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a three-dimensional schematic diagram of the flange plate according to Example 1 being installed on the blade root end surface of the mold;

[0021] Figure 2 for Figure 1 Schematic diagram of the disassembly, in which the bolt sleeve is hidden;

[0022] Figure 3 for Figure 2 A partial schematic diagram of

[0023] Figure 4 This is a longitudinal cross-sectional schematic diagram of the flange being installed on the blade root end surface of the mold in the initial stage of manufacturing the blade in Example 1;

[0024] Figure 5 for Figure 4 A partial enlarged schematic diagram;

[0025] Figure 6 This is a cross-sectional schematic diagram showing that after the blade is manufactured and glue-filled as described in Example 1, the blade expands backward due to heat, and the flange retreats after being subjected to force F (F=F1+F2) to form an expansion gap between the blade root end face of the mold and the flange;

[0026] Figure 7 This is a longitudinal cross-sectional view of the flange mounted on the blade root end face of the mold during the initial stage of manufacturing the blade according to Example 2;

[0027] Figure 8 This is a three-dimensional schematic diagram of Example 3 after a piston body is added to the outer end of the blind hole.

[0028] In the figure: 1. mold; 101. root end face of the mold; 102. blind hole; 103. annular sink; 2. flange; 3. exhaust gap; 4. expansion gap; 5. fixing bolt; 501. bolt handle; 6. compression spring; 7. thermal expansion airbag; 8. elastic baffle; 9. piston body; 10. pressure plate; 11. countersunk screw; 12. stainless steel bushing; 13. blade; 131. root end face of the blade; 1. 4 bolt sleeve. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the embodiments and accompanying drawings: Example 1

[0030] like Figure 1 As shown in FIG6 , a wind turbine blade 13 is manufactured within a mold 1 whose inner surface corresponds to the outer surface of a longitudinally sectioned half of the wind turbine blade. To pre-embed bolt sleeves 14, a flange 2 is used on the mold's blade root end face 101 to position the bolt sleeves 14 (this is conventional technology).

[0031] A method for controlling the gap between the root end face and the flange of a pre-embedded blade mold is disclosed. During the initial stage of blade 13 production, only an exhaust gap 3 is reserved between the flange 2 and the root end face 101 of the mold. When the blade 13 thermally expands, the flange 2, while maintaining contact with the root end face 131, retracts backward to form an expansion gap 4 between the flange 2 and the root end face 101 of the mold, thereby satisfying the space requirement for the blade root end face 131 to expand outward. The exhaust gap 3 is very small, merely satisfying exhaust requirements while preventing molten adhesive from overflowing. The method of retracting the flange 2 while maintaining contact with the root end face 131 of the blade is to prevent the molten adhesive from being blocked during the production of the blade 13, thereby maintaining a smooth and flat blade root end face 131. If the flange 2 does not maintain contact with the root end face 131 during the retraction process, it is difficult to ensure that the root end face 131 of the blade can expand outward in a neat manner. In this way, under the premise of avoiding glue overflow, it is ensured that the flange 2 and the blade root end face 101 of the mold can be normally vented, and when the poured molten glue expands due to heat, the flange 2 can retreat to form an expansion gap 4 between it and the blade root end face 101 of the mold, making room for the blade root end face 131 of the blade to expand backward.

[0032] The spacing of the exhaust gap 3 is designed to be 0.1-0.3 mm, such as 0.1 mm, 0.2 mm, 0.3 mm. This spacing can prevent glue overflow and ensure exhaust.

[0033] In order to make the flange 2 retract backward while maintaining contact with the root end face 131 of the blade, the bolt shank 501 of the fixing bolt 5 is used to press the flange 2 through the compression spring 6, and the flange 2 is forced to retract by applying a backward force F to the flange 2, overcoming the elastic force of the compression spring 6.

[0034] The backward force F applied to the flange 2 utilizes the backward expansion force F1 exerted on the flange 2 by the blade root end face 131 due to thermal expansion of the blade 13. However, if the backward expansion force F1 exerted by the blade root end face 131 on the flange 2 due to thermal expansion is solely relied upon to overcome the resistance of the compression spring, the blade root end face 131 will still bulge toward the inner wall of the blade 13 due to excessive resistance. Therefore, the backward force F applied to the flange 2 requires the assistance of an external force F2.

[0035] A plurality of blind holes 102 are axially provided on the blade root end face 101 of the mold, and thermal expansion bladders 7 are provided in the blind holes 102. When the glue is poured, the heat from the melt causes the blade 13 to expand, and at the same time, the thermal expansion bladders 7 to expand. The external force F2 is the backward force exerted on the flange 2 by the thermal expansion bladder 7 when it expands. Figure 6 It is a schematic diagram showing that the flange 2 retreats after receiving a force F (F=F1+F2) to form an expansion gap 4 between the blade root end face 101 of the mold and the flange 2.

[0036] Furthermore, an elastic barrier sheet 8 is installed at the opening of blind hole 102. This barrier sheet seals the thermal expansion bag 7 within blind hole 102, transfers the pressure of the thermal expansion bag 7 to the flange 2, and relies on the tensile deformation of the elastic barrier sheet 8 to ensure that the thermal expansion bag 7 expands and pushes the flange back. This prevents glue overflow or debris from entering blind hole 102, ensuring that the thermal expansion bag 7 can expand and retract normally.

[0037] A concave annular sink 103 is provided on the periphery of the blind hole 102 , and an annular pressing plate 10 is added. The pressing plate 10 fixes the periphery of the elastic baffle 8 on the annular sink 103 via countersunk screws 11 .

[0038] Furthermore, the thickness of annular pressure plate 10 is set so that it protrudes from the mold's blade root end face 101 by 0.1-0.3 mm. The flange 2 is pressed against the annular pressure plate 10, forming an exhaust gap 3 between the mold's blade root end face 101 and the flange 2. This ensures that the spacing of the exhaust gap 3 is controlled within 0.1-0.3 mm without requiring additional configuration, while also forming a dike around the blind hole 102 to prevent any overflowing glue from adhering to the elastic spacer 8 and affecting its elasticity. Example 2

[0039] like Figure 7As shown, based on the first embodiment, a thermal expansion bag 7 is placed at the inner end of the blind hole 102, and a piston body 9 is installed at the outer end of the blind hole 102. When the thermal expansion bag 7 expands, the pressure pushes the piston body 9 backward, and is transmitted to the flange 2 through the piston body 9. This prevents the thermal expansion bag 7 from expanding out of the blind hole 102 and affecting the magnitude of the backward expansion pressure. With the piston body 9 installed, the expansion pressure of the thermal expansion bag 7 can be directed entirely toward the flange 2. Example 3

[0040] like Figure 8 As shown, this embodiment is a further measure of the above embodiment. A stainless steel bushing 12 is added to the inner wall of the blind hole 102. Firstly, it can ensure that the blind hole 102 will not be damaged during long-term use. Secondly, it can increase the smoothness, which is conducive to the smooth expansion and retraction of the thermal expansion bag 7 and the piston body 9.

[0041] The above embodiments are only used to more clearly describe the present invention and cannot be regarded as limiting the scope of protection covered by the present invention. Any modifications in equivalent forms should be regarded as falling within the scope of protection covered by the present invention.

Claims

1. A method for controlling the gap between the root end face and flange of a pre-embedded blade mold, characterized by: In the initial stage of manufacturing the blade (13), only an exhaust gap (3) is reserved between the flange (2) and the blade root end face (101) of the mold. When the blade (13) generates thermal expansion, the flange (2) is made to retreat backward while maintaining contact with the blade root end face (131) to form an expansion gap (4) between the flange (2) and the blade root end face (101) of the mold, thereby meeting the space requirement for the blade root end face (131) to expand outward; the flange (2) is made to retreat backward while maintaining contact with the blade root end face (131), by using the bolt shank (501) of the fixing bolt (5) to press the flange (2) through the compression spring (6), and the flange (2) is retreated by applying a backward force F to the flange (2); the flange (2) is made to retreat by applying a backward force F to the flange (2) applying a backward force F, which also includes an external force F2; a plurality of blind holes (102) are axially arranged on the blade root end face (101) of the mold, and a thermal expansion airbag (7) is arranged in the blind hole (102). When the glue is poured, the heat of the melt causes the blade (13) to expand while the thermal expansion airbag (7) expands. The external force F2 is the backward force applied to the flange (2) when the thermal expansion airbag (7) expands; an elastic baffle (8) is arranged at the orifice of the blind hole (102), and the elastic baffle (8) seals the thermal expansion airbag (7) in the blind hole (102). The elastic baffle transmits the pressure of the thermal expansion airbag (7) on the flange (2), and relies on the tensile deformation of the elastic baffle (8) to ensure that the thermal expansion airbag (7) expands and pushes the flange back.

2. The method for controlling the gap between the root end face and the flange of the embedded blade mold according to claim 1, characterized in that: The spacing of the exhaust gap is 0.1-0.3 mm.

3. The method for controlling the gap between the root end face and the flange of the embedded blade mold according to claim 1, characterized in that: The backward force F applied to the flange (2) includes utilizing the backward expansion pressure F1 applied by the blade root end surface (131) of the blade to the flange (2) when the blade (13) generates thermal expansion.

4. The method for controlling the gap between the root end face and the flange of the embedded blade mold according to claim 1, characterized in that: The thermal expansion bag (7) is placed at the inner end of the blind hole (102), and a piston body (9) is arranged at the outer end of the blind hole (102). The expansion pressure of the thermal expansion bag (7) when it expands is transmitted to the flange (2) through the piston body (9).

5. The method for controlling the gap between the root end face and the flange of the embedded blade mold according to claim 1, characterized in that: A concave annular sink (103) is provided on the periphery of the blind hole (102), and an annular pressing plate (10) is added. The pressing plate (10) fixes the periphery of the elastic baffle (8) on the annular sink (103) via countersunk screws (11).

6. The method for controlling the gap between the root end face and the flange of the embedded blade mold according to claim 5, characterized in that: The thickness of the annular pressing plate (10) is set so that the annular pressing plate (10) protrudes 0.1-0.3 mm from the blade root end surface (101) of the mold, and the flange (2) is pressed against the annular pressing plate (10) so that an exhaust gap (3) is formed between the blade root end surface (101) of the mold and the flange (2).

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