Ultra-high-strength embedded thread sleeve and blade root embedded part

Abstract

The invention discloses an ultra-high-strength embedded threaded sleeve and blade root embedded part which comprises a blade root threaded sleeve end and a blade tip threaded sleeve end, and the outer diameter of the blade tip threaded sleeve end is larger than that of the blade root threaded sleeve end. An internal thread is arranged on the inner side of the blade tip thread sleeve end, and a dovetail-shaped groove is formed in the inner side of the end part of the blade tip thread sleeve end; and a plurality of annular grooves are formed in the outer wall of the pre-embedded screw sleeve. According to the pre-embedded thread sleeve, the received drawing force can be shared on the UD block, so that the drawing resistance of the pre-embedded thread sleeve is greatly improved under the condition that the strength of the blade root glass fiber reinforced plastic and the strength of the UD block are not changed, and the interface performance of the pre-embedded thread sleeve meets the ultrahigh-load blade root connection requirement.

Description

Technical Field

[0001] The present invention relates to the field of wind power generation, and particularly to a super-high-strength embedded bushing and a root embedment of a blade. Background Art

[0002] With the improvement of the power rating of wind turbines, the blades of wind turbine generators are also developing towards larger and longer sizes. To meet the requirements of higher mechanical power and the transmission of larger loads, the root connection problem of wind turbine blades becomes particularly important. The embedded bolt sleeve connection can achieve multi-bolt connection with the same pitch circle diameter compared to the T-bolt connection, meeting the requirements of higher root loads. Therefore, at present, most high-power blades in the industry adopt the embedded bushing connection.

[0003] The interfacial performance of the embedded bushing is the core performance index of the embedded root connection solution. At present, in the industry, mainly by increasing the outer diameter and length of the bushing to increase the bonding area of the bushing so as to improve the interfacial performance of the bushing. However, this method has certain limitations because the interfacial performance of the bushing is mainly related to the bonding area and the strength of the fiberglass and UD blocks. When the root thickness remains unchanged, after the outer diameter of the bushing becomes larger, the geometric dimensions of the fiberglass and UD blocks will decrease, and the strength will correspondingly decrease under the condition of unchanged raw materials. After the outer diameter and length of the bushing increase to a certain extent, there is no obvious improvement in the interfacial performance of the bushing. Without changing the strength of the root fiberglass and UD blocks, the existing interfacial performance of the embedded bushing cannot reach an ultra-high level to meet the requirements of the root connection with ultra-high loads. Summary of the Invention

[0004] The present invention aims to provide an embedded bushing that can greatly improve the interfacial performance to solve problems such as the difficulty of the existing embedded bushing in meeting the root connection requirements with ultra-high loads. The embedded bushing of the present invention can distribute the pulling force to the UD blocks, and without changing the strength of the root fiberglass and UD blocks, achieve a significant increase in the anti-pulling force of the embedded bushing to meet the root connection requirements with ultra-high loads.

[0005] To achieve the above object, the basic scheme of the present invention is as follows: A super-high-strength embedded bushing, comprising: a root bushing end and a tip bushing end, and the outer diameter of the tip bushing end is greater than the outer diameter of the root bushing end; an internal thread is provided inside the tip bushing end, and a dovetail-shaped slot is opened inside the end of the tip bushing end; a plurality of annular grooves are opened on the outer wall of the embedded bushing.

[0006] Further, the embedded bushing adopts an integral tapered bushing structure.

[0007] Further, the embedded bushing adopts a partial tapered bushing structure.

[0008] Further, the embedded bushing adopts a stepped bushing structure.

[0009] A root tip embedded part includes a super-high-strength embedded bushing as described above, and further includes: a wedge block and a UD block; the wedge block abuts against the tip bushing end of the embedded bushing; the UD block includes a first UD block and a second UD block, which are mirror structures and symmetrically arranged, wrapping the two sides of the embedded bushing and the wedge block to form an integral root tip embedded part, and the first UD block and the second UD block have the same slope as the wedge block.

[0010] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: A super-high-strength embedded bushing is designed, including a root bushing end and a tip bushing end, and the cross-section of the tip bushing end is larger than the cross-sectional diameter of the root bushing end, increasing the contact area between the tip bushing end and the UD block, enhancing the anti-pulling force of the embedded bushing, and since the tip bushing end is larger than the root bushing end, the embedded bushing cannot be pulled out alone, but needs to pull out the UD block together or make the UD block extrude and fail before it can be pulled out, sharing the pulling force borne by the embedded bushing to the UD block, and greatly enhancing the anti-pulling force of the embedded bushing without changing the strength of the root fiberglass and the UD block; an internal thread is provided on the inner side of the embedded bushing near the tip bushing end for installing the root bolt, and a dovetail-shaped slot is provided on the inner side of the tip bushing end, making the inner wall thickness of the bushing end gradually decrease to avoid stress concentration at the end; a plurality of annular grooves are provided on the outer wall of the embedded bushing, increasing the contact area with structures such as the UD block and further enhancing the anti-pulling force of the embedded bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic structural diagram of a super-high-strength embedded bushing in an embodiment;

[0012] Figure 2 It is a schematic structural diagram of an embedded bushing with a partial conical structure in an embodiment;

[0013] Figure 3 It is a schematic structural diagram of another embedded bushing with a partial conical structure in an embodiment;

[0014] Figure 4 It is a schematic structural diagram of an embedded bushing with a stepped structure in an embodiment;

[0015] Figure 5 It is a schematic structural diagram of a root tip embedded part in an embodiment;

[0016] Figure 6 It is a schematic structural diagram of a root tip embedded part using an integral conical structure embedded bushing, a partial conical structure embedded bushing, and a stepped embedded bushing in an embodiment;

[0017] Figure 7Schematic structural diagram of a traditional cylindrical embedded stud in an embodiment;

[0018] Figure 8 3D model of a cylindrical embedded stud in an embodiment;

[0019] Figure 9 3D model of a conical embedded stud in an embodiment;

[0020] Figure 10 Stress nephogram of a cylindrical embedded stud in an embodiment;

[0021] Figure 11 Stress nephogram of an overall conical embedded stud in an embodiment. Detailed implementation manners

[0022] In order to make the present invention clearer and more understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0023] As Figure 1 shown, a super-high-strength embedded stud is provided, including: a root stud end 10 and a tip stud end 20, and the outer diameter of the tip stud end 20 is greater than the outer diameter of the root stud end 10; an internal thread 30 is provided inside the tip stud end 20, and a dovetail-shaped slot 40 is provided inside the end of the tip stud end 20; a plurality of annular grooves 50 are provided on the outer wall of the embedded stud.

[0024] In this embodiment, a super-high-strength embedded stud is designed, including a root stud end 10 and a tip stud end 20, and the outer diameter of the tip stud end 20 is greater than the outer diameter of the root stud end 10, which increases the contact area between the tip stud end 20 and the UD block, improves the tensile and pull-out resistance of the embedded stud, and the outer diameter of the tip stud end 20 is greater than the outer diameter of the root stud end 10, so that the embedded stud cannot be pulled out alone, but needs to pull out the UD block together or squeeze the UD block until it fails before it can be pulled out, sharing the tensile and pull-out force borne by the embedded stud to the UD block, and greatly improving the tensile and pull-out resistance of the embedded stud without changing the strength of the root fiberglass and the UD block; an internal thread 30 is provided inside the tip stud end 20 for installing the root bolt, and a dovetail-shaped slot 40 is provided inside the end of the tip stud end 20, so that the inner wall thickness of the end of the stud gradually decreases, avoiding stress concentration at the end; a plurality of annular grooves 50 are provided on the outer wall of the embedded stud, increasing the contact area with structures such as the UD block, and further improving the tensile and pull-out resistance of the embedded stud.

[0025] Among them, the embedded bushing adopts an integral conical bushing structure.

[0026] Specifically, as Figure 1 shown, an integral conical bushing structure is adopted. The embedded bushing is conical as a whole, making the outer diameter of the tip bushing end larger than that of the root bushing end to enhance the tensile force of the embedded bushing.

[0027] As Figure 2 and Figure 3 shown, the embedded bushing adopts a partial conical bushing structure.

[0028] Specifically, as Figure 2 shown, the embedded bushing adopts a bushing structure with a partial taper, finally presenting the effect that the outer diameter of the tip bushing end is larger than that of the root bushing end; as Figure 3 shown, the embedded bushing adopts a cylindrical bushing structure at one end and a conical bushing structure at the other end, and can also achieve the effect that the outer diameter of the tip bushing end is larger than that of the root bushing end.

[0029] Among them, the embedded bushing adopts a stepped bushing structure.

[0030] Specifically, as Figure 4 shown, a stepped bushing structure is adopted for the embedded bushing, that is, cylindrical bushing structures with different outer diameters are adopted at the root bushing end and the tip bushing end to achieve the effect that the outer diameter of the tip bushing end is larger than that of the root bushing end.

[0031] In one embodiment, as Figure 5 shown, a root embedment is further provided, which includes a super-high-strength embedded bushing 100 as described above, and further includes: a wedge block 70 and a UD block 60; the wedge block 70 abuts against the tip bushing end of the embedded bushing; the UD block 60 includes a first UD block 61 and a second UD block 62, which are mirror structures and symmetrically arranged, wrapping the two sides of the embedded bushing 100 and the wedge block 70 to form an integral root embedment, and the first UD block 61 and the second UD block 62 have the same slope as the wedge block 70.

[0032] In this embodiment, based on the above-mentioned ultra-high-strength embedded screw sleeve, a blade root embedded part is obtained, which includes an embedded screw sleeve 100, a UD block 60, and a wedge block 70. The wedge block 70 abuts against the blade tip screw sleeve end of the embedded screw sleeve. The UD block 60 includes a first UD block 61 and a second UD block. The two are mirror structures and are symmetrically arranged. The first UD block 61 and the second UD block 62 wrap the two sides of the embedded screw sleeve 100 and the wedge block 70 to form an integral blade root embedded part. The first UD block 61 and the second UD block 62 have the same slope as the wedge block 70. By connecting the embedded screw sleeve 100 and the UD block 60, the effective bonding area of the embedded screw sleeve is increased. Without changing the strength of the blade root fiberglass and the UD block, the tensile pull-out force of the embedded screw sleeve 100 can be greatly increased to meet the requirements of the blade root connection load.

[0033] Among them, as Figure 6 shown, the blade root embedded parts are composed of embedded screw sleeves with an overall conical screw sleeve structure, a partial conical screw sleeve structure, and a stepped screw sleeve structure. Among them, (a) is the blade root embedded part composed of an embedded screw sleeve with an overall conical screw sleeve structure, (b) is the blade root embedded part composed of an embedded screw sleeve with a partial conical screw sleeve structure, and (c) is the blade root embedded part composed of an embedded screw sleeve with a stepped screw sleeve structure.

[0034] In one embodiment, in order to verify that the ultra-high-strength embedded screw sleeve of the present invention has higher interfacial performance than the existing cylindrical embedded screw sleeve to meet the requirements of ultra-high load blade root connection, theoretical design, finite element simulation, and experimental verification were carried out on the effectiveness of the ultra-high-strength embedded screw sleeve. The specific implementation plan includes:

[0035] The relevant blade root connection parameters are shown in Table 1.

[0036] Table 1 Blade root connection parameters

[0037] Name Unit Specific Value Root Wall Thickness of Blade mm 100 Outer Diameter of Sleeve (D) mm 60 <![CDATA[Outer diameter (D1) of the end sleeve of the blade root stud]]> mm 56 Outer Diameter of Sleeve at Blade Tip (D2) mm 64 Length of Sleeve (L) mm 445 <![CDATA[Length of the lower bottom edge of the UD block (L1)]]> mm 1200 <![CDATA[Length of the upper base edge of the UD block (L2)]]> mm 455 <![CDATA[Length of the lower base of the wedge block (L3)]]> mm 800 <![CDATA[Distance from the upper base of the wedge block to the ellipse (L4)]]> mm 50 Major Axis Diameter (A) of Ellipse in Wedge Block mm 860 Minor Axis Radius (B) of Ellipse in Wedge Block mm 20 Bottom Width (W) of First UD Block mm 42

[0038] The traditional cylindrical embedded screw sleeve is as Figure 7 shown. The tensile pull-out force borne by the cylindrical screw sleeve is entirely determined by the effective bonding area on the outer surface of the screw sleeve. The formula for the effective bonding area of the cylindrical screw sleeve is:

[0039] S1 = π * D * L

[0040] According to the blade root connection parameters and the above formula, the calculated effective bonding area of the cylindrical embedded screw sleeve is 75360 mm 2 .

[0041] The integral conical embedded bushing of the present invention is compared with the traditional cylindrical embedded bushing. Due to the uniqueness of the structural form of the embedded bushing and the UD block of the present invention, the large end of the embedded bushing is located inside the UD block, and the integral conical embedded bushing and the UD block are bound into a whole. To pull out the embedded bushing, it is necessary to pull out the UD block together or pull it out after squeezing the UD block to failure. The pulling force borne by the embedded bushing is shared by the UD block. Therefore, the pulling force that the embedded bushing can withstand is jointly determined by the bonding area between the outer surface of the bushing and the fiberglass and the bonding area between the outer surface of the UD block and the fiberglass. The calculation formula for the effective bonding area is:

[0042] S 锥 = S2 + S3

[0043] In the formula, S2 is the bonding area between the outer surface of the bushing and the fiberglass, and S3 is the bonding area between the outer surface of the UD block and the fiberglass. The formula is:

[0044] S2 = π * (D1 / 2 + D2 / 2) * L

[0045] S3 = W * (L1 + L2 + A) - π * B * A / 2

[0046] Calculated through the blade root connection parameters and the above formula, S2 = 83645mm 2 , S3 = 78626mm 2 , then the effective bonding area of the embedded bushing of the present invention is S 锥 = 162271mm 2 .

[0047] Through the above calculation, by comparing the effective bonding areas of the cylindrical embedded bushing and the embedded bushing of the present invention, it can be seen that compared with the cylindrical embedded bushing, the effective bonding area of the embedded bushing of the present invention is increased by 94%, and the theoretical pulling strength of the bushing after the bonding area is increased is also increased by 94%.

[0048] However, it is necessary to consider whether the ultimate shear strength of the UD block can be withstand. The shear strength of the UD block is calculated according to G xy = 56Mpa, then the pulling force that the UD block can withstand is:

[0049] F N = π * (D1 / 2 + D2 / 2) * L * G xy

[0050] Calculated according to the blade root connection parameters, F N is greater than 4700KN, that is, the UD block can withstand a pulling force of more than 4700KN. Therefore, the UD block is not the bottleneck of the interface performance.

[0051] Such as Figure 8 and 9As shown, three-dimensional models of the cylindrical embedded stud and the overall conical embedded stud of the present invention are established respectively. Corresponding finite element models of the blade root connection are established in the finite element software. Under the same load and boundary conditions, the shear stresses at the interfaces of the cylindrical embedded stud and the conical embedded stud are calculated respectively. The corresponding stress nephograms are as shown in Figure 10 and 11 As shown, through finite element calculation, the interface stress of the cylindrical embedded stud is 592.4 Mpa, and the interface stress of the overall conical embedded stud is 296 Mpa.

[0052] In one embodiment, samples are prepared and tested for the cylindrical embedded stud and the conical embedded stud of the present invention respectively. The test results are shown in Table 2 and Table 3.

[0053] Table 2 Static Pull-out Test Results of Cylindrical Embedded Stud

[0054] Specimen Number <![CDATA[Ultimate bearing capacity F i (kN)]]> S-1# 1023 S-2# 1040 S-3# 1052 S-4# 1049 S-5# 1033

[0055] Table 3 Static Pull-out Test Results of the Conical Embedded Stud of the Present Invention

[0056]

[0057]

[0058] Through the sample preparation test, the static pull-out results of the embedded stud without taper and with taper are obtained. Obviously, the conical embedded stud of the present invention has a greater ultimate bearing capacity compared with the traditional cylindrical embedded stud, verifying the effectiveness of the theory and finite element simulation. The conical embedded stud has higher interface performance and can meet the higher blade root load connection requirements.

[0059] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0060] The above are only embodiments of the present invention. Specific structures and characteristics and other common knowledge in the art are not described in detail herein. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention pertains before the filing date or the priority date, are able to learn all the prior arts in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to complete and implement this solution. Some typical well-known structures or well-known methods should not become an obstacle for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can also be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. An ultra-high-strength embedded screw sleeve, characterized in that, Comprising: A root-end screw sleeve and a tip-end screw sleeve, and the outer diameter of the tip-end screw sleeve is greater than that of the root-end screw sleeve; Internal threads are provided inside the tip-end screw sleeve, and a dovetail-shaped slot is provided inside the end of the tip-end screw sleeve; A plurality of annular grooves are provided on the outer wall of the embedded screw sleeve.

2. The ultra-high strength embedded screw sleeve according to claim 1, characterized in that, The embedded screw sleeve adopts an integral tapered screw sleeve structure.

3. The ultra-high-strength embedded screw sleeve according to claim 1, wherein, The embedded screw sleeve adopts a partial tapered screw sleeve structure.

4. The ultra-high-strength embedded screw sleeve according to claim 1, characterized in that, The embedded screw sleeve adopts a stepped screw sleeve structure.

5. A blade root embedded part, characterized in that, An ultra-high-strength embedded screw sleeve according to any one of claims 1-4, further comprising: A wedge block and a UD block; The wedge block abuts against the tip-end screw sleeve end of the embedded screw sleeve; The UD block includes a first UD block and a second UD block, which are mirror structures and symmetrically arranged, wrapping the two sides of the embedded screw sleeve and the wedge block to form an integral root-end embedded part, and the first UD block and the second UD block have the same slope as the wedge block.

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