A method for preparing the web of a wind turbine blade and its molding die

Abstract

This invention relates to the field of wind turbine blade manufacturing technology, specifically providing a molding die for a wind turbine blade web, including a support frame and a heating and vacuuming assembly located on the support frame. The support frame has an upper platform and a side platform, with a movable stop on the side platform and a receiving gap between the side end of the upper platform and the stop. A removable soft pad is provided in the receiving gap, with the upper end face of the soft pad flush with the upper end face of the upper platform. This invention also provides a method for manufacturing a wind turbine blade web, including steps S1: installing the stop according to the width requirement of the receiving gap; S2: laying multiple layers of fiberglass cloth; S3: placing the soft pad in the receiving gap; S4: folding the lower part of a portion of the fiberglass cloth along the height direction and extending it onto the upper platform; S5: performing further layering operations on the upper platform to complete the web manufacturing. The molding die and manufacturing method of this invention are applicable to both C-shaped and I-shaped webs.

Description

Technical Field

[0001] This invention relates to the field of wind turbine blade manufacturing technology, and in particular to a method for manufacturing the web of a wind turbine blade and its molding die. Background Technology

[0002] Wind energy, as a pollution-free, renewable, and green energy source, has enormous development potential, especially for coastal islands, remote mountainous areas, grasslands, pastures, and rural and border regions far from or difficult to reach by the power grid in the short term. It is of great significance as a reliable way to solve energy problems for production and daily life. Wind energy has the advantages of low energy consumption, environmental friendliness, and large reserves. The utilization of wind energy is usually achieved by converting wind energy into electrical energy through wind turbines, thereby generating electricity through wind power. Wind turbine blades are one of the core components of wind turbines, and wind power generation requires wind turbine blades.

[0003] Wind turbine blades are typically hollow composite material products composed of a leeward and a windward side. The hollow portion is supported along its length by a web, making the web a crucial component of wind turbine blades. Existing technologies include the following patents relating to wind turbine blade webs or their fabrication processes:

[0004] 1. A utility model patent with patent number "201520812881.7" and patent title "A Universal Wind Turbine Blade Web Mold" includes a steel frame and a steel base plate. The steel base plate has at least two sets of steel upright plates, each set consisting of two plates. The two upright plates are arranged on both sides of the steel base plate along the length of the wind turbine blade web. The bottom edge of each upright plate is connected to the steel base plate via a detachable mechanism. This design can accelerate the production speed of the web, facilitate the replacement of steel upright plates for different wind turbine blade web molds, and improve the forming efficiency of different wind turbine blade webs.

[0005] 2. The invention patent with patent number "201310037981.2" and patent title "A Method for Preparing a Wind Turbine Blade Web Mold" includes the following steps: 1) Prefabricating a foundation support; 2) Laying a mold heating layer on top of the foundation support; 3) Laying a surface steel plate on the mold heating layer; 4) Setting a flanging mechanism on the surface steel plate; 5) Opening vacuum holes on the outside of the flanging mechanism; 6) Connecting each section of the wind turbine blade web mold sequentially from the widest to the narrowest section along its length using end connecting components to form a complete wind turbine blade web mold. This method is simple, low-cost, and the mold is not easily deformed and can be reused.

[0006] 3. Patent No. "202110814583.1", entitled "A Wind Turbine Blade I-Shaped Web Mold and Its Preparation Method", describes an invention patent for a wind turbine blade web mold comprising a mold plate, a baffle, a heating layer, an insulation layer, height-adjustable feet, a vacuum interface, and insulation and heating components. The web preparation includes the following steps: welding height-adjustable feet to the bottom surface of the mold plate; arranging a heating layer on the bottom surface of the mold plate; arranging an insulation layer above the heating layer; installing a baffle on the upper surface of the mold plate; and machining a vacuum interface. This invention solves the problem of how to efficiently prepare wind turbine blade webs.

[0007] However, the aforementioned existing technologies still have the following problems:

[0008] 1. It can only be applied to one of the C-type web molds or I-type web molds, and cannot meet the processing requirements of both C-type web molds and I-type web molds at the same time;

[0009] 2. The stop block of this web plate mold is not conducive to the demolding of web plate products with negative draft angle, which can easily lead to damage to the bonding surface of the web plate.

[0010] 3. Existing I-type web bonding flanges are not convenient for layup fabrication and demolding of web products.

[0011] In summary, designing a mold and molding method for wind turbine blade webs that facilitates product demolding and layup, and is compatible with both C-shaped and I-shaped webs, is an urgent problem to be solved. Summary of the Invention

[0012] To solve the above problems, the present invention provides a method for preparing the web of a wind turbine blade and its molding die, which can prepare the web of wind turbine blades of different specifications and blade shapes, and can simultaneously meet the processing requirements of C-shaped webs and I-shaped webs and facilitate product demolding.

[0013] To achieve the above objectives, the present invention proposes the following technical solution: a molding die for a wind turbine blade web, comprising a support frame and a heating assembly and a vacuum assembly located on the support frame. The support frame is provided with a central upper platform and a side platform located below the side of the upper platform. A movable stop block is provided on the side platform, and a receiving gap is left between the side end of the upper platform and the stop block. A removable soft pad is provided in the receiving gap, and the upper end face of the soft pad is flush with the upper end face of the upper platform. The width of the receiving gap is adjusted by horizontally moving the stop block on the side platform.

[0014] Preferably, the stop includes a bottom mounting block located on the side platform and a side limiting block extending upward from the side end of the bottom mounting block near the upper platform to above the upper platform. The accommodating gap is formed by the space between the side limiting block and the upper platform. An upper connection point D1 and a lower connection point D2 are formed between the side limiting block and the pad. The upper connection point D1 is the intersection of the upper end face of the pad and the side limiting block, and the upper connection point D1 forms the first inflection point of the web ply. The lower connection point D2 is the intersection of the lower end face of the pad and the side limiting block, and the lower connection point D2 forms the second inflection point of the web ply.

[0015] Preferably, a screw is fixedly connected to the side platform, and a connecting through hole is provided on the bottom mounting block to match the screw, and the width of the connecting through hole is greater than the outer diameter of the screw. The connecting through hole provides an adjustable horizontal displacement space for the stop block to adjust the width of the accommodating gap between the side limiting block and the upper platform. After the stop block is installed on the screw through the connecting through hole, a nut is installed on the screw on the bottom mounting block to fix the stop block.

[0016] Preferably, adjusting bolt one and adjusting bolt two are respectively provided on the support frame below the upper platform and below the side platform. The height of the upper platform and the side platform can be adjusted by adjusting bolt one and adjusting bolt two respectively to adjust the flatness of the web and meet the processing requirements of webs of different specifications.

[0017] Preferably, the support frame includes a lower support and an upper support located between the upper platform and the lower support, and a side support is connected between the side ends of the upper support and the lower support; the vacuum assembly includes a vacuum nozzle and a vacuum pipe connected to the vacuum nozzle and located on the side support, the vacuum nozzle being located outside the side support and connected to the bottom of the side platform.

[0018] Preferably, both adjusting bolt one and adjusting bolt two include a double-ended stud and adjusting rods threaded to both ends of the double-ended stud; adjusting bolt one is integrally located between the upper platform and the upper support, and adjusting bolt two is integrally located between the side platform and the upper support and is located directly above the side support.

[0019] Preferably, the heating assembly includes a heating pipe 1 located at the lower end of the upper platform, a heating pipe 2 located at the lower end of the side platform, an insulation layer 1 located at the lower end of the heating pipe 2, and an insulation layer 2 located at the lower end of the heating pipe 2; a heat-conducting layer 1 is formed between the heating pipe 1, the insulation layer 1, and the upper platform, and a heat-conducting layer 2 is formed between the heating pipe 2, the insulation layer 2, and the side platform; the heating pipe 2, the insulation layer 2, and the heat-conducting layer 2 are all located inside the adjusting bolt 2; a heating pipe communicating with the heating pipe 1 and the heating pipe 2 is provided on the side bracket.

[0020] A method for preparing a wind turbine blade web, comprising the above-mentioned molding die, wherein when preparing a C-shaped web, the method includes the following steps:

[0021] S1: Adjust the stop block to the corresponding position on the side platform according to the width requirement of the clearance, and fix the stop block on the bottom mounting block with nuts and screws;

[0022] S2: Place the pad in the receiving gap, and ensure that the upper surface of the pad is flush with the upper surface of the upper platform;

[0023] S3: Lay multiple layers of fiberglass cloth from top to bottom along the height direction on the inner wall of the side limiting block to the upper connection point D1;

[0024] S4: Starting from connection point D1, extend the fiberglass cloth horizontally to the upper platform;

[0025] S5: Perform further layup operations on the upper platform and complete the preparation of the web.

[0026] A method for preparing a wind turbine blade web, comprising the following steps when manufacturing an I-shaped web:

[0027] S1: Adjust the stop block to the corresponding position on the side platform according to the width requirement of the clearance, and fix the stop block on the bottom mounting block with nuts and screws;

[0028] S2: Lay multiple layers of fiberglass cloth along the height direction on the inner wall of the side limiting block, and fold the lower part of part of the fiberglass cloth upward along the height direction.

[0029] S3: Place the pad in the receiving gap, and ensure that the upper surface of the pad is flush with the upper surface of the upper platform;

[0030] S4: Extend the folded fiberglass cloth horizontally to the upper platform, starting from the connection point D1 above;

[0031] S5: Perform further layup operations on the upper platform and complete the preparation of the web.

[0032] Preferably, step S2 includes the following sub-steps:

[0033] S21: Lay the fiberglass cloth downwards to the lower connection point D2;

[0034] S22: Fold the fiberglass cloth above the connection point D1, which is away from the inner wall of the side limiting block, upwards.

[0035] The beneficial effects of this invention are:

[0036] 1. The preparation method and molding die in this invention have strong applicability. The height of the upper platform and the side platform can be adjusted by adjusting bolt one and adjusting bolt two respectively to adjust the flatness of the web and match the height of the web. The width of the web can be matched by moving the stop block horizontally. In this way, webs of wind turbine blades of different specifications and blade shapes can be prepared, and the processing requirements of C-shaped webs and I-shaped webs can be met at the same time.

[0037] 2. In this invention, there is a receiving gap between the stop block and the upper platform, and a soft pad is provided in the receiving gap. Both the stop block and the soft pad are movable structures, which reduces the technical difficulty of operation and the professional requirements of the staff.

[0038] 3. The side limiting blocks are connected by two inflection points with fiberglass cloth, which can accommodate the processing of C-shaped and I-shaped webs and facilitate the demolding of web products with negative draft angles, thus avoiding damage to the web bonding surface. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the molding die provided in Embodiment 1 of the present invention.

[0040] Figure 2 yes Figure 1 A magnified view of a section at point A (without fiberglass cloth).

[0041] Figure 3 This is a schematic diagram of the fiberglass cloth laying structure provided in the embodiment of the present invention (fiberglass cloth has been laid).

[0042] Figure 4 This is a schematic diagram of the fiberglass cloth laying structure provided in Embodiment 2 of the present invention (fiberglass cloth has been laid).

[0043] Reference numerals: Upper platform 1, Side platform 2, Stop block 3, Soft pad 5, Bottom mounting block 6, Side limiting block 7, Screw 8, Nut 10, Adjusting bolt one 11, Adjusting bolt two 12, Upper bracket 13, Lower bracket 14, Side bracket 15, Vacuum extraction nozzle 16, Vacuum pipe 17, Double-ended stud 18, Adjusting rod 19, Heat insulation plate 20, Heating tube one 21, Heating tube two 22, Insulation layer one 23, Insulation layer two 24, Heat-conducting layer one 25, Heat-conducting layer two 26, Heating pipe 27, Fiberglass cloth 28. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-4 The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof. Example 1

[0045] A molding die for the web of a wind turbine blade, such as Figure 1-3 As shown, the device includes a support frame and heating and vacuum components located on the support frame. The support frame has a central upper platform 1 and a side platform 2 located below the side of the upper platform 1. The side platform 2 has a movable stop block 3. There is a receiving gap between the side end of the upper platform 1 and the stop block 3. A removable soft pad 5 is provided in the receiving gap. The upper end face of the soft pad 5 is flush with the upper end face of the upper platform 1, so that the forming mold can process both C-shaped and I-shaped webs. The width of the receiving gap can be adjusted by moving the stop block 3 horizontally on the side platform 2, so that the forming mold can process webs of different widths. In this embodiment, the soft pad 5 is a silicone pad.

[0046] like Figure 1 As shown, the support frame includes a lower support 14 and an upper support 13. The upper support 13 is located between the upper platform 1 and the lower support 14. A side support 15 connects the side ends of the upper support 13 and the lower support 14. Adjusting bolt 11 and adjusting bolt 12, respectively, are located on the support frame below the upper platform 1 and the side platform 2. Adjusting bolt 11 is entirely located between the upper platform 1 and the upper support 13, and adjusting bolt 12 is entirely located between the side platform 2 and the upper support 13, directly above the side support 15. The heights of the upper platform 1 and the side platform 2 are adjusted by adjusting bolts 11 and 12 respectively to adjust the flatness of the web and meet the processing requirements of webs with different height specifications. Figure 1 , 2 As shown, both adjusting bolt 11 and adjusting bolt 2 12 include a double-ended stud 18 and an adjusting rod 19 threaded to both ends of the double-ended stud 18; a heat insulation plate 20 is provided between adjusting bolt 2 12 and the side platform 2.

[0047] like Figure 1 As shown, the vacuum assembly includes a vacuum nozzle 16 and a vacuum pipe 17 connected to the vacuum nozzle 16. The vacuum pipe 17 is located on the side support 15, and the vacuum nozzle 16 is located outside the side support 15 and connected to the bottom of the side platform 2.

[0048] like Figure 1 , 2 As shown, the heating assembly includes a heating pipe 21 located at the lower end of the upper platform 1, an insulation layer 23 located at the lower end of the heating pipe 21, a heating pipe 22 located at the lower end of the side platform 2, and an insulation layer 24 located at the lower end of the heating pipe 22. A heat-conducting layer 25 is formed between the heating pipe 21, the insulation layer 23, and the upper platform 1, and a heat-conducting layer 26 is formed between the heating pipe 22, the insulation layer 24, and the side platform 2. The heating pipe 22, the insulation layer 24, and the heat-conducting layer 26 are all located inside the adjusting bolt 12. A heating pipe 27 connected to the heating pipe 21 and the heating pipe 22 is provided on the side bracket 15.

[0049] like Figure 2 , 3 As shown, the stop block 3 includes a bottom mounting block 6 and a side limiting block 7. The bottom mounting block 6 is located on the side platform 2. The side limiting block 7 is formed by extending upward from the side end of the bottom mounting block 6 near the upper platform 1. The side limiting block 7 extends above the upper platform 1, and the accommodating gap is formed by the space between the side limiting block 7 and the upper platform 1. A screw 8 is fixedly connected to the side platform 2. In this embodiment, the screw 8 is fixed to the upper end of the side platform 2 by welding. The bottom mounting block 6 is provided with a connecting through hole that matches the screw 8. The width of the connecting through hole is greater than the outer diameter of the screw 8. The connecting through hole provides an adjustable horizontal displacement space for the stop block 3 to adjust the width of the accommodating gap between the side limiting block 7 and the upper platform 1. After the stop block 3 is installed on the screw 8 through the connecting through hole, a nut 10 is installed on the bottom mounting block 6 onto the screw 8 to fix the stop block 3.

[0050] like Figure 2 , 3 As shown, an upper connection point D1 and a lower connection point D2 are formed between the side limiting block 7 and the soft pad 5. The upper connection point D1 is the intersection of the upper end face of the soft pad 5 and the side limiting block 7, and the upper connection point D1 forms the first inflection point of the web ply. The lower connection point D2 is the intersection of the lower end face of the soft pad 5 and the side limiting block 7, and the lower connection point D2 forms the second inflection point of the web ply.

[0051] A method for preparing a wind turbine blade web, wherein the wind turbine blade web is prepared using the above-mentioned molding die, such as... Figure 3 As shown, the following steps are included when fabricating a C-shaped web:

[0052] S1: Adjust the stop block 3 to the corresponding position on the side platform 2 according to the width requirement of the accommodating gap, and fix the stop block 3 on the bottom mounting block 6 by using the nut 10 and the screw 8.

[0053] S2: Place the cushion 5 in the receiving gap, and ensure that the upper surface of the cushion 5 is flush with the upper surface of the upper platform 1.

[0054] S3: Lay multiple layers of fiberglass cloth 28 from top to bottom along the height direction on the inner wall of the side limiting block 7 to the upper connection point D1; the number of layers of fiberglass cloth 28 is set according to actual needs, preferably 2-8 layers of fiberglass cloth 28, and in this embodiment, 4 layers of fiberglass cloth 28 are specifically laid.

[0055] S4: Starting from connection point D1, extend the two layers of fiberglass cloth 28 away from the inner wall of the side limiting block 7 horizontally to the upper platform 1; the fiberglass cloth 28 laid on the upper platform 1 as follows: Figure 3 As shown at point M.

[0056] S5: Perform further layup operations on the upper platform 1 and complete the preparation of the web. Example 2

[0057] The difference between this embodiment and Embodiment 1 is that, as Figure 4 As shown, the following steps are included when manufacturing the web of the I-shaped mold:

[0058] S1: Adjust the stop block 3 to the corresponding position on the side platform 2 according to the width requirement of the accommodating gap, and fix the stop block 3 on the bottom mounting block 6 by using the nut 10 and the screw 8.

[0059] S2: Lay multiple layers of fiberglass cloth 28 along the height direction on the inner wall of the side limiting block 7, and fold the lower part of part of the fiberglass cloth 28 upward along the height direction; the number of layers of fiberglass cloth 28 is set according to actual needs, preferably 2-8 layers of fiberglass cloth 28 are laid, and in this embodiment, 4 layers of fiberglass cloth 28 are specifically laid.

[0060] S21: Lay the fiberglass cloth 28 downwards to the lower connection point D2;

[0061] S22: Fold the two layers of fiberglass cloth 28 above the connection point D1, which is away from the inner wall of the side limiting block 7, upwards.

[0062] S3: Place the soft pad 5 in the receiving gap, ensuring that the upper surface of the soft pad 5 is flush with the upper surface of the upper platform 1; the fiberglass cloth 28 laid between the soft pad 5 and the side limiting block 7 is as follows: Figure 4 As shown at point N in the middle.

[0063] S4: Starting from connection point D1, extend the folded two layers of fiberglass cloth 28 horizontally onto the upper platform 1; the fiberglass cloth 28 laid on the upper platform 1 is as follows: Figure 4 As shown at point M.

[0064] S5: Perform further layup operations on the upper platform 1 and complete the preparation of the web.

[0065] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0066] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing the web of a wind turbine blade, characterized in that, The following molding die is used to manufacture the web of the wind turbine blade. The molding die includes a support frame and a heating component and a vacuum component located on the support frame. The support frame is provided with a central upper platform (1) and a side platform (2) located below the side of the upper platform (1). The side platform (2) is provided with a movable stop block (3) and there is a gap between the side end of the upper platform (1) and the stop block (3). A removable soft pad (5) is provided in the gap. The upper end face of the soft pad (5) is flush with the upper end face of the upper platform (1). The width of the gap is adjusted by moving the stop block (3) horizontally on the side platform (2). Adjusting bolt one (11) and adjusting bolt two (12) are respectively located on the support frame below the upper platform (1) and below the side platform (2). The height of the upper platform (1) and the side platform (2) is adjusted by adjusting bolt one (11) and adjusting bolt two (12) respectively to adjust the flatness of the web and meet the processing requirements of webs of different specifications. The stop block (3) includes a bottom mounting block (6) located on the side platform (2) and a side limiting block (7) extending upward from the side end of the bottom mounting block (6) near the upper platform (1) to the upper platform (1). The accommodating gap is formed by the space between the side limiting block (7) and the upper platform (1). The side limiting block (7) and the pad (5) form an upper connection point D1 and a lower connection point D2. The upper connection point D1 is the intersection of the upper end face of the pad (5) and the side limiting block (7) and the upper connection point D1 forms the first inflection point of the web ply. The lower connection point D2 is the intersection of the lower end face of the pad (5) and the side limiting block (7) and the lower connection point D2 forms the second inflection point of the web ply. When fabricating a C-shaped web, the following steps are included: S1: Adjust the stop block (3) to the corresponding position on the side platform (2) according to the width requirement of the accommodating gap, and fix the stop block (3) on the bottom mounting block (6) by using nuts (10) and screws (8); S2: Place the pad (5) in the receiving gap and ensure that the upper surface of the pad (5) is flush with the upper surface of the upper platform (1); S3: Lay multiple layers of fiberglass cloth (28) from top to bottom along the height direction on the inner wall of the side limiting block (7) to the upper connection point D1; S4: Starting from the connection point D1 above, extend the fiberglass cloth (28) horizontally to the upper platform (1); S5: Perform further lay-up operations on the upper platform (1) and complete the preparation of the web; When manufacturing the web of an I-shaped plate, the following steps are included: S1: Adjust the stop block (3) to the corresponding position on the side platform (2) according to the width requirement of the accommodating gap, and fix the stop block (3) on the bottom mounting block (6) by using nuts (10) and screws (8); S2: Lay multiple layers of fiberglass cloth (28) along the height direction on the inner wall of the side limiting block (7), and fold the lower part of part of the fiberglass cloth (28) upward along the height direction; it includes the following sub-steps: S21: Lay the fiberglass cloth (28) downwards to the lower connection point D2; S22: Fold the fiberglass cloth (28) above the connection point D1, which is away from the inner wall of the side limiting block (7), upwards; S3: Place the pad (5) in the receiving gap and ensure that the upper surface of the pad (5) is flush with the upper surface of the upper platform (1); S4: Extend the folded fiberglass cloth (28) from the connection point D1 above to the upper platform (1) in a horizontal direction; S5: Perform further lay-up operations on the upper platform (1) and complete the preparation of the web.

2. The preparation method according to claim 1, characterized in that, A screw (8) is fixedly connected to the side platform (2). A connecting through hole is provided on the bottom mounting block (6) to match the screw (8), and the width of the connecting through hole is greater than the outer diameter of the screw (8). The connecting through hole provides adjustable horizontal displacement space for the stop block (3) to adjust the width of the gap between the side limiting block (7) and the upper platform (1). After the stop block (3) is installed on the screw (8) through the connecting through hole, the nut (10) is installed on the screw (8) on the bottom mounting block (6) to fix the stop block (3).

3. The preparation method according to claim 2, characterized in that, The support frame includes a lower support (14) and an upper support (13) located between the upper platform (1) and the lower support (14). A side support (15) is connected between the side ends of the upper support (13) and the lower support (14). The vacuum assembly includes a vacuum nozzle (16) and a vacuum pipe (17) communicating with the vacuum nozzle (16) and located on the side support (15). The vacuum nozzle (16) is located outside the side support (15) and connected to the bottom of the side platform (2).

4. The preparation method according to claim 3, characterized in that, Both the first adjusting bolt (11) and the second adjusting bolt (12) include a double-ended stud (18) and an adjusting rod (19) threaded to both ends of the double-ended stud (18); the first adjusting bolt (11) is located between the upper platform (1) and the upper bracket (13), and the second adjusting bolt (12) is located between the side platform (2) and the upper bracket (13) and is located directly above the side bracket (15).

5. The preparation method according to claim 4, characterized in that, The heating assembly includes a heating pipe 1 (21) located at the lower end of the upper platform (1), a heating pipe 2 (22) located at the lower end of the side platform (2), an insulation layer 1 (23) located at the lower end of the heating pipe 1 (21), and an insulation layer 2 (24) located at the lower end of the heating pipe 2 (22); a heat-conducting layer 1 (25) is formed between the heating pipe 1 (21), the insulation layer 1 (23), and the upper platform (1), and a heat-conducting layer 2 (26) is formed between the heating pipe 2 (22), the insulation layer 2 (24), and the side platform (2); the heating pipe 2 (22), the insulation layer 2 (24), and the heat-conducting layer 2 (26) are all located inside the adjusting bolt 2 (12); a heating pipe (27) connected to the heating pipe 1 (21) and the heating pipe 2 (22) is provided on the side bracket (15).

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