Wind power blade mold

Abstract

The invention discloses a wind power blade mold, and relates to the technical field of wind power blade manufacturing, the wind power blade mold comprises a plurality of splicing modules, the plurality of splicing modules are respectively spliced and combined into a blade root mold and a blade tip mold, and in the blade root mold, the plurality of splicing modules are sequentially spliced in the circumferential direction of the wind power blade mold. According to the technical scheme, the blade root mold is formed by splicing the multiple splicing modules in the circumferential direction of the wind power blade mold, a traditional integral mold is divided into the multiple transportation units, the transportation size of a single piece is effectively reduced, and the situation that a large wind power blade mold is difficult to transport is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of wind turbine blade manufacturing, and in particular to a wind turbine blade mould. Background Art

[0002] Large-scale wind turbine blades are an important technical path to improve power generation efficiency and reduce power generation costs. As the size of blades continues to increase, the size of their manufacturing molds also increases accordingly. However, the difficulty of manufacturing and transporting giant molds has increased significantly, especially since existing road transportation conditions are difficult to meet the requirements, which has become a key bottleneck restricting the industrialization process of large-megawatt wind power equipment. Summary of the invention

[0003] The main purpose of the present invention is to provide a wind turbine blade mould, aiming to improve the problem of difficult transportation of existing blade manufacturing moulds.

[0004] To achieve the above object, the wind turbine blade mold proposed in the present invention comprises a plurality of splicing modules, wherein the plurality of splicing modules are spliced ​​and combined into a blade root mold and a blade tip mold, and the blade root mold and the blade tip mold are spliced ​​and arranged along the length direction of the wind turbine blade mold;

[0005] In the blade root mould, a plurality of the splicing modules are spliced ​​and arranged in sequence along the circumference of the wind turbine blade mould.

[0006] In one embodiment, in the blade root mold, at least part of the splicing modules are spliced ​​in the height direction and / or width direction of the wind turbine blade mold.

[0007] In one embodiment, the splicing module includes a template and a bracket, the template has an inner side surface and an outer side surface opposite to each other, and the bracket is fixedly arranged on the outer side surface of the template;

[0008] Among them, the brackets of two adjacent splicing modules are detachably connected through a positioning structure, so that the corresponding two templates can be aligned and spliced, and a plurality of templates can be detachably connected to each other to form a mold body.

[0009] In one embodiment, in the blade root mold, the template has a first end facing away from the blade tip mold;

[0010] The bracket forms a limiting portion, and the limiting portion extends to the side of the first end.

[0011] In one embodiment, the limiting portion is locked and connected to the first end of the template by a limiting bolt.

[0012] In one embodiment, the bracket is formed with a docking plane, and two adjacent brackets are docked through the docking plane;

[0013] The positioning structure includes a plurality of positioning bolts, which are arranged in an interval distribution in the docking plane, and the positioning bolts are locked to connect the two brackets.

[0014] In one embodiment, two adjacent templates are aligned and connected via a docking structure so that the inner side surfaces of the two templates are aligned and flush.

[0015] In one embodiment, a first butt joint boss is formed on a side of the splicing edge of one of the templates close to the inner side surface, and a second butt joint boss is formed on a side of the splicing edge of the other template close to the outer side surface, and the first butt joint boss is overlapped with the second butt joint boss;

[0016] The docking structure includes the first docking boss and the second docking boss.

[0017] In one embodiment, a connecting flange is formed on the outer side of the template near its splicing edge;

[0018] In two adjacent splicing modules, the two connecting flanges are locked and connected by connecting bolts.

[0019] In one embodiment, the connecting bolt is also locked and connected to the corresponding two brackets.

[0020] According to the technical solution provided by the present invention, a wind turbine blade mold is composed of a plurality of splicing modules, and the plurality of splicing modules can be spliced ​​together to form a blade root mold and a blade tip mold, wherein the plurality of splicing modules constituting the blade root mold are spliced ​​in sequence along the circumference of the wind turbine blade mold, so that after the blade root mold is split into a plurality of splicing modules, its overall height or width can be reduced, thereby alleviating the problem of the blade root mold being too high or too wide, that is, alleviating the problem of the difficulty in transporting the wind turbine blade mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the top view of the structure of an embodiment of a wind turbine blade mold provided by the present invention;

[0023] Figure 2 A front view structural schematic diagram of an embodiment of a wind turbine blade mold provided by the present invention;

[0024] Figure 3 for Figure 2 Schematic diagram of the exploded structure of a wind turbine blade mold.

[0025] Description of Figure Numbers:

[0026] 100. Wind turbine blade mold;

[0027] 10a, blade root mold; 10b, blade tip mold; 1, splicing module; 1a, first module; 1b, second module; 1c, third module; 1d, fourth module; 11, bracket; 11a, docking plane; 111, limiting part; 12, template; 121, first end; 122, connecting flange; 2, positioning structure; 21, positioning bolt; 3, docking structure; 31, first docking boss; 32, second docking boss; 4, connecting bolt; 5, limiting bolt.

[0028] X, length direction; Y, width direction; Z, height direction; W, circumferential direction.

[0029] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that if a directional indication is involved in the embodiment of the present invention, the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] Large-scale wind turbine blades are an important technical path to improve power generation efficiency and reduce power generation costs. As the size of blades continues to increase, the corresponding manufacturing molds also increase accordingly. However, the difficulty of manufacturing and transporting giant molds has increased significantly, especially the existing road transportation conditions are difficult to meet the requirements, which has become a key bottleneck restricting the industrialization process of large-megawatt wind power equipment.

[0034] In view of the above technical bottlenecks, the present invention discloses a wind turbine blade mold, which effectively improves the transportation and transshipment problems of blade manufacturing molds under existing land transportation conditions through modular technology innovation. To facilitate understanding of the wind turbine blade mold proposed by the present invention, the following is an explanation in conjunction with the accompanying drawings, in which: Figure 1 A schematic diagram of the top view of the structure of an embodiment of a wind turbine blade mold provided by the present invention; Figure 2 A front view structural schematic diagram of an embodiment of a wind turbine blade mold provided by the present invention; Figure 3 for Figure 2 Schematic diagram of the exploded structure of a wind turbine blade mold.

[0035] See also Figures 1 to 3 The wind turbine blade mold 100 proposed in the present invention includes a plurality of splicing modules 1, and the plurality of splicing modules 1 are respectively spliced ​​and combined into a blade root mold 10a and a blade tip mold 10b, and the blade root mold 10a and the blade tip mold 10b are spliced ​​and arranged along the length direction of the wind turbine blade mold 100; in the blade root mold 10a, the plurality of splicing modules 1 are spliced ​​and arranged in sequence along the circumference of the wind turbine blade mold 100.

[0036] It should be noted that "a plurality of splicing modules 1 are spliced ​​and combined to form a blade root mold 10a and a blade tip mold 10b" means that the blade root mold 10a is formed by splicing parts of a plurality of splicing modules 1, while the blade tip mold 10b is formed by splicing the remaining parts of the splicing modules 1. This embodiment only limits the blade root mold 10a to be spliced ​​in sequence along the circumferential direction W of the wind turbine blade mold 100 by a plurality of splicing modules 1, but does not limit how the blade tip mold 10b is specifically spliced ​​by a plurality of splicing modules 1. It is worth mentioning that the blade root of a wind turbine blade usually has a large chord length, which makes the root width and height dimensions of the wind turbine blade mold 100 large, that is, the width and height dimensions of the blade root mold 10a are large, which is not conducive to mold transportation. This embodiment does not limit how to splice the multiple splicing modules 1 in the blade tip mold 10b. The multiple splicing modules 1 in the blade tip mold 10b can be spliced ​​along the circumferential direction W of the wind turbine blade mold 100, or can be spliced ​​along the length direction X of the wind turbine blade mold 100. Of course, it can also be a combination of the above two splicing methods. The blade root mold 10a and the blade tip mold 10b are spliced ​​along the length direction X of the wind turbine blade mold, which should also be understood as the splicing of the splicing modules 1 at corresponding positions in each mold.

[0037] According to the technical solution provided by the present invention, a wind turbine blade mold 100 is composed of a plurality of splicing modules 1, and the plurality of splicing modules 1 can be spliced ​​together to form a blade root mold 10a and a blade tip mold 10b, wherein the plurality of splicing modules 1 constituting the blade root mold 10a are spliced ​​in sequence along the circumferential direction W of the wind turbine blade mold 100, so that after the blade root mold 10a is split into a plurality of splicing modules 1, its overall height or width can be reduced, thereby alleviating the problem of the blade root mold 10a being too high or too wide, that is, alleviating the problem of the difficulty in transporting the wind turbine blade mold 100.

[0038] In one embodiment, the splicing module 1 includes a template 12 and a bracket 11, the template 12 has relative inner and outer sides, and the bracket 11 is fixedly arranged on the outer side of the template 12; wherein, the brackets 11 of two adjacent splicing modules 1 are detachably connected through a positioning structure 2 so that the corresponding two templates 12 can be aligned and spliced, and multiple templates 12 can be detachably connected to each other to form a mold body.

[0039] It should be noted that the templates 12 of multiple splicing modules 1 can form a mold body under the connection of the bracket 11, and the inner side surface of the template 12 also constitutes the inner wall surface of the mold cavity of the mold body, which is used to form wind turbine blades; the bracket 11 is fixedly arranged on the outer side surface of the template 12, and there are various fixing methods, such as welding fixation or riveting fixation, which is not limited in this embodiment. Due to the fixed connection of the bracket 11, it can at least be determined that the bracket 11 contributes to the rigidity improvement of the template 12. For example, the bracket 11 is configured to have support points at various local positions on the outer side surface of the template 12; the brackets 11 of two adjacent splicing modules 1 are detachably connected through a positioning structure 2. There are various structural forms of this positioning structure 2, such as the matching connection of the positioning pin and the positioning hole, the matching plug-in of the positioning block and the positioning groove, etc., which is not limited in this embodiment; after the two adjacent brackets 11 are connected through the positioning structure 2, the corresponding two templates 12 can be aligned and spliced, that is, they constitute a part of the mold body, that is, the splicing edges of the two templates 12 are adapted to be connected, so that the inner sides of the two are smoothly connected. “Multiple templates 12 are detachably connected to each other” means that the templates 12 are also detachably connected to each other. When they need to be spliced ​​to form a mold body, they are connected to each other and can be repeatedly disassembled when they need to be transported. There are many structural forms of such detachable connections. For example, there is a snap-fit ​​structure between two adjacent templates 12, which are connected by snap-fit ​​combination. This embodiment does not limit this.

[0040] In the above technical scheme, the wind turbine blade mold 100 is composed of a plurality of splicing modules 1. In the splicing module 1, the bracket 11 is fixedly arranged on the outer side of the template 12, which is beneficial to increase the rigidity of the template 12. During transportation, the bracket 11 can be placed on the transport vehicle as a supporting basis, reducing the impact of the bumpy transportation process on the shape of the template 12. During the hoisting and transportation process, the hoist can act on the bracket 11, which can also reduce the impact on the shape of the template 12. The brackets 11 of the two splicing modules 1 are connected as one through the positioning structure 2, which can ensure that the two templates 12 are accurately aligned and spliced, which is beneficial to improving the overall geometric accuracy and long-term reliability of the mold body.

[0041] In one embodiment, in the blade root mold 10 a , at least part of the splicing modules 1 are spliced ​​in the height direction Z and / or the width direction Y of the wind turbine blade mold 100 .

[0042] It should be noted that the above embodiment includes three parallel technical solutions, namely, "in the blade root mold 10a, at least part of the splicing modules 1 are spliced ​​in the height direction Z of the wind turbine blade mold 100", "in the blade root mold 10a, at least part of the splicing modules 1 are spliced ​​in the width direction Y of the wind turbine blade mold 100" and "in the blade root mold 10a, at least part of the splicing modules 1 are spliced ​​in the height direction Z of the wind turbine blade mold 100, and at least part of the splicing modules 1 are spliced ​​in the width direction Y of the wind turbine blade mold 100".

[0043] In the above technical scheme, the splicing modules 1 are spliced ​​in the height direction Z of the wind turbine blade mold 100, so the height dimension of a single splicing module 1 is obviously smaller than that of the blade root mold 10a, which can undoubtedly solve the problem of the wind turbine blade mold 100 being too high during transportation; the splicing modules 1 are spliced ​​in the width direction Y of the wind turbine blade mold 100, so the width dimension of a single splicing module 1 is obviously smaller than that of the blade root mold 10a, which can undoubtedly solve the problem of the wind turbine blade mold 100 being too wide during transportation; it can be known that in the blade root mold 10a, at least part of the splicing modules 1 are spliced ​​in the height direction Z of the wind turbine blade mold 100, and at least part of the splicing modules 1 are spliced ​​in the width direction Y of the wind turbine blade mold 100, which can solve both the problem of the wind turbine blade mold 100 being too high during transportation and the problem of the wind turbine blade mold 100 being too wide during transportation.

[0044] In one embodiment, in the blade root mold 10 a , the template 12 has a first end 121 away from the blade tip mold 10 b ; the bracket 11 forms a limiting portion, and the limiting portion extends to the side of the first end 121 .

[0045] It should be noted that "the template 12 has a first end 121 away from the blade tip mold 10b", wherein the first end 121 refers to the first end 121 away from the blade tip mold 10b along the length direction X in the wind turbine blade mold 100, and the first end 121 of the template 12 usually corresponds to the bottom end of the root of the wind turbine blade. The first end 121 does not have a splicing edge and does not need to be spliced ​​with other templates 12. "The limiting portion extends to the side of the first end 121" means that the limiting portion overlaps with the template 12 in the length direction X of the wind turbine blade mold 100, and is arranged away from the blade tip mold 10b compared to the template 12 of the blade root mold 10a.

[0046] In the above technical solution, full use is made of the first end 121 of the template 12 of the blade root mold 10a which does not need to participate in the splicing, and a limiting portion is set on the side of the first end 121. During the transportation of the blade root mold 10a, the limiting portion can be used to limit the position of the template 12, thereby improving the reliability of the connection between the template 12 and the bracket 11.

[0047] Furthermore, in one embodiment, the limiting portion is locked and connected to the first end 121 of the template 12 by a limiting bolt 5 .

[0048] It should be noted that the template 12 usually has a certain thickness, and the "limiting portion is locked and connected to the first end 121 of the template 12 by the limiting bolt 5", that is, the first end 121 of the template 12 is formed with a threaded hole in the physical structure in the thickness direction, and the limiting bolt 5 is adapted to be connected to the threaded hole, so as to connect and fasten the limiting portion to the template 12. The limiting portion is usually set as a flange structure, of course, it is not limited to this, as long as it can provide a locking basis for the limiting bolt 5.

[0049] In the above technical solution, the limiting bolts 5 are used to lock and connect to the template 12 and the limiting part, which further improves the connection firmness between the bracket 11 and the template 12 in the splicing module 1 of the blade root mold 10a, that is, improves the accuracy of the template 12 connected through the bracket 11 to achieve aligned splicing.

[0050] Specifically, in the blade root mold 10a, the multiple splicing modules 1 include a first module 1a, a second module 1b, a third module 1c and a fourth module 1d. The second module 1b and the third module 1c are located at the bottom of the blade root mold 10a and are spliced ​​in the width direction Y. The first module 1a and the fourth module 1d are located at the top of the blade root mold 10a and are spliced ​​to the second module 1b and the third module 1c in the height direction Z, respectively.

[0051] In one embodiment, the bracket 11 is formed with a docking plane 11a, and two adjacent brackets 11 are docked through the docking plane 11a; the positioning structure 2 includes a plurality of positioning bolts 21, and the plurality of positioning bolts 21 are arranged at intervals in the docking plane 11a, and the positioning bolts 21 lock and connect the two brackets 11.

[0052] It should be noted that the brackets 11 and 11 are in contact through the docking plane 11a. Under the premise of ensuring the flatness of the docking plane 11a, the connection accuracy between the brackets 11 can be guaranteed; the "docking plane 11a" usually has an extension direction, and "a plurality of positioning bolts 21 are arranged at intervals in the docking plane 11a" means that a plurality of positioning bolts 21 are distributed at intervals in the docking plane 11a along its extension direction. "The positioning bolts 21 are locked to connect the two brackets 11". It should be understood that there are corresponding positioning holes in the docking plane 11a, and the screw of the positioning bolt 21 passes through the positioning holes on the two docking planes 11a and is locked and connected with the matching nut. The locking connection of a plurality of positioning bolts 21 can not only completely limit the freedom of relative movement between the two brackets 11, but also achieve a simple and highly reliable detachable connection.

[0053] In one embodiment, two adjacent templates 12 are aligned and connected via a docking structure 3 so that the inner side surfaces of the two templates 12 are aligned and flush.

[0054] It should be noted that the docking structure 3 is a structure that ensures that the splicing edges of the two templates 12 are accurately docked. Due to the existence of the docking structure 3, after the two templates 12 are aligned and connected, their inner sides can be aligned and flush, that is, smoothly connected. There are many specific forms of this docking structure 3. For example, the splicing edge of one template 12 is formed with a docking pin, and the splicing edge of the other template 12 is formed with a matching socket. The connection between the docking pin and the matching socket can ensure the accurate docking of the two templates 12. This embodiment does not limit the specific structural form of the docking structure 3.

[0055] In one embodiment, a first docking boss 31 is formed on the splicing edge of one template 12 on the side close to the inner side surface, and a second docking boss 32 is formed on the splicing edge of the other template 12 on the side close to the outer side surface, and the first docking boss 31 and the second docking boss 32 are overlapped; the docking structure 3 includes a first docking boss 31 and a second docking boss 32.

[0056] It should be noted that "a first docking boss 31 is formed on the splicing edge of one of the templates 12 on the side close to the inner side surface", that is, the first docking boss 31 is located at the splicing edge of the main part of the template 12, and participates in constituting the inner side surface of the template 12; "a second docking boss 32 is formed on the splicing edge of the other template 12 on the side close to the outer side surface", that is, the second docking boss 32 is located at the splicing edge of the main part of the template 12, and participates in constituting the outer side surface of the template 12; "the first docking boss 31 and the second docking boss 32 are overlapped", that is, there is a certain first clearance gap between the first docking boss 31 and the outer side surface, and there is a certain second clearance gap between the second docking boss 32 and the inner side surface, the first docking boss 31 extends into the second clearance gap, and the second docking boss 32 extends into the first clearance gap, thereby realizing the overlap of the first docking boss 31 and the second docking boss 32 in the direction from the inside to the outside.

[0057] In the above technical solution, the two adjacent templates 12 can ensure pre-docking with each other through the overlapping setting of the first docking boss 31 and the second docking boss 32. On this basis, the two brackets 11 are connected, which can accurately grasp the docking accuracy between the templates 12 and eliminate the connection error between the brackets 11.

[0058] In one embodiment, a connection flange 122 is formed on the outer side of the template 12 near its splicing edge; in two adjacent splicing modules 1, the two connection flanges 122 are locked and connected by connecting bolts 4.

[0059] It should be noted that “the two connecting flanges 122 are locked and connected by the connecting bolts 4 ” can be understood as that a connecting through hole is provided on the connecting flange 122 , and the connecting bolts 4 are locked and connected with the connecting nuts through the connecting through holes of the two connecting flanges 122 .

[0060] In the above technical solution, based on the connection of the bracket 11, through the design of the connecting flange 122, the two templates 12 can be connected and locked from the outside using the connecting bolts 4, ensuring that multiple templates 12 can form a solid mold body, further improving the overall accuracy of the mold body.

[0061] In one embodiment, the connecting bolts 4 are also locked and connected to the corresponding two brackets 11 .

[0062] In the above technical solution, the connecting bolt 4 is locked and connected to the corresponding two brackets 11 on the basis of locking the two connecting flanges 122, and is also locked and connected to the corresponding two brackets 11, thereby participating in the connection between the brackets 11 and 11, and improving the connection firmness between the templates 12 and the templates 12, between the templates 12 and the brackets 11, and between the brackets 11 and the brackets 11.

[0063] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A wind turbine blade mold, characterized in that: It comprises a plurality of splicing modules (1), wherein the plurality of splicing modules (1) are spliced ​​and assembled into a blade root mold (10a) and a blade tip mold (10b), and the blade root mold (10a) and the blade tip mold (10b) are spliced ​​and arranged along the length direction of the wind turbine blade mold; In the blade root mould (10a), a plurality of the splicing modules (1) are spliced ​​and arranged in sequence along the circumference of the wind turbine blade mould.

2. The wind turbine blade mold according to claim 1, characterized in that: In the blade root mould (10a), at least part of the splicing modules (1) are spliced ​​in the height direction and / or width direction of the wind turbine blade mould.

3. The wind turbine blade mold according to claim 1, characterized in that: The splicing module (1) comprises a template (12) and a bracket (11); the template (12) has an inner side surface and an outer side surface that are opposite to each other; and the bracket (11) is fixedly arranged on the outer side surface of the template (12); The brackets (11) of two adjacent splicing modules (1) are detachably connected via a positioning structure (2) so that the corresponding two templates (12) can be aligned and spliced, and a plurality of templates (12) can be detachably connected to each other to form a mold body.

4. The wind turbine blade mold according to claim 3, characterized in that: In the blade root mold (10a), the template (12) has a first end (121) facing away from the blade tip mold (10b); The bracket (11) forms a limiting portion, and the limiting portion extends to the side of the first end (121).

5. The wind turbine blade mold according to claim 4, characterized in that: The limiting portion is locked and connected to the first end (121) of the template (12) via a limiting bolt (5).

6. The wind turbine blade mold according to claim 3, characterized in that: The bracket (11) is formed with a docking plane (11a), and two adjacent brackets (11) are docked via the docking plane (11a); The positioning structure (2) comprises a plurality of positioning bolts (21), the plurality of positioning bolts (21) being arranged in a spaced distribution within the docking plane (11a), and the positioning bolts (21) are locked to connect the two brackets (11).

7. The wind turbine blade mold according to claim 3, characterized in that: Two adjacent templates (12) are aligned and connected via a docking structure (3) so that the inner side surfaces of the two templates (12) are aligned and flush.

8. The wind turbine blade mold according to claim 7, characterized in that: A first butt joint protrusion (31) is formed on a side of the splicing edge of one of the templates (12) close to the inner side surface, and a second butt joint protrusion (32) is formed on a side of the splicing edge of the other template (12) close to the outer side surface, and the first butt joint protrusion (31) and the second butt joint protrusion (32) are overlapped and arranged; The docking structure (3) comprises the first docking boss (31) and the second docking boss (32).

9. The wind turbine blade mold according to claim 3, characterized in that: The outer side surface of the template (12) is formed with a connecting flange (122) near its splicing edge; In two adjacent splicing modules (1), the two connecting flanges (122) are locked and connected by connecting bolts (4).

10. The wind turbine blade mold according to claim 9, characterized in that: The connecting bolt (4) is also locked and connected to the corresponding two brackets (11).

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