A positioning device suitable for heat shield welding

Abstract

The application discloses a positioning device suitable for heat shield welding, which comprises a plurality of positioning channel steels, two I-shaped steels, a plurality of positioning blocks, a plurality of fastening devices and a plurality of arc-shaped rib plates. The positioning channel steels are arranged between the two I-shaped steels. The arc-shaped rib plates are fixedly welded with arc-shaped pasting plates on the top. The heat shield is placed on the arc-shaped pasting plates. One I-shaped steel is fixedly arranged on the inclined surface on one side of the positioning channel steels and is welded with the lower flange of the I-shaped steel. Another I-shaped steel is fixedly arranged on the inclined surface on the other side of the positioning channel steels and is welded with the lower flange of the other I-shaped steel. The two ends of the arc-shaped rib plates are respectively welded with the webs of the two I-shaped steels close to the upper flanges. The positioning blocks are fixedly arranged on the upper flanges of the I-shaped steels and abut against the two ends of the heat shield. The positioning blocks are used for positioning and abutting against the two ends of the heat shield.

Description

Technical Field

[0001] This invention belongs to the field of thin-wall welding technology, and particularly relates to a positioning device suitable for hot-screen welding. Background Technology

[0002] As a core component of the spent fuel storage system in the 600MW high-temperature gas-cooled reactor demonstration project, the importance of the spent fuel shaft equipment is self-evident. It is mainly responsible for the hoisting guidance, support, cooling, and shielding functions of the storage tank, with a design life of up to 70 years. The equipment is mainly composed of key components such as heat shield supports, guide rail supports, guide rails, guide rail fixing plates, heat shields, temperature measuring baffles, and shaft covers.

[0003] The design of the heat shield is particularly crucial. It not only effectively blocks heat radiation from the storage tank to the concrete walls but also forms a ventilation channel with the shaft and the tank. Cool air flows from top to bottom on the outside of the heat shield and enters the inside of the heat shield through openings at the bottom of the shaft. Then, it flows from bottom to top through the 50mm gap between the inside of the heat shield and the spent fuel tank, carrying the heat emitted by the spent fuel tank to the outside atmosphere. The heat shield adopts a four-part structure and is installed on a guide rail fixing plate. It is mainly made of 3mm and 5mm thin plates processed by welding. The heat shield plate and stiffening plate are connected by intermittent welding. The two ends of the heat shield are welded with L-shaped bent plates. The post-weld rigidity is poor, making secondary machining impossible. Furthermore, the stainless steel shrinks significantly during welding, making drilling difficult. Strict control of the dimensional tolerances of each hole is necessary during manufacturing to ensure proper fit with the guide rail fixing plate.

[0004] Given the large batch demand and high manufacturing precision requirements of vertical shaft heat shields, there is an urgent need for a positioning device suitable for heat shield welding. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention proposes a positioning device suitable for hot-screen welding.

[0006] The technical solution adopted by this invention to solve its technical problem is: a positioning device suitable for hot-screen welding, the device comprising several positioning channel steels, two I-beams, several positioning blocks, several fastening devices, and several arc-shaped stiffeners; several positioning channel steels are installed between the two I-beams; an arc-shaped plate is fixedly welded above the arc-shaped stiffeners; the hot screen is placed above the arc-shaped plate; the arc of the arc-shaped stiffeners matches the inner arc of the arc-shaped plate, and the arc of the arc-shaped plate matches the inner arc of the hot screen; the cross-sectional shape of each positioning channel steel is an isosceles trapezoid; and an I-beam is vertically fixed on the inclined surface of one side of several positioning channel steels. The lower flange of the I-beam is welded to the lower flange of the I-beam. Another I-beam is vertically fixed on the inclined surface on the other side of several positioning channel steels and welded to the lower flange of the other I-beam. The two ends of the arc-shaped stiffener are respectively welded to the web of the two I-beams near the upper flange. A U-shaped notch is opened at each end of the arc-shaped stiffener. The upper flange of the I-beam has a first screw hole corresponding to the hole at the bottom of both ends of the heat shield. The fastening device passes through the hole and is fixedly installed in the first screw hole of the upper flange of the I-beam. The positioning block is fixedly set on the upper flange of the I-beam and abuts against both ends of the heat shield. The positioning block is used to position and abut against both ends of the heat shield.

[0007] Preferably, the fastening device includes a bolt and nut assembly and a positioning cone pin. The bolt and nut assembly and the positioning cone pin of the fastening device are staggered in the first screw holes of the I-beam. One bolt and nut assembly is installed every three first screw holes, and the positioning cone pin is installed in the remaining first screw holes.

[0008] Preferably, the axis of the I-beam is aligned with the normal direction of the corresponding side slope of the positioning channel steel, and the included angle between them is 90°.

[0009] Preferably, a plate is spot-welded to the upper flange of each I-beam, and a second screw hole is opened on the plate corresponding to the hole at the bottom of both ends of the heat shield. The plate is placed between the end of the heat shield and the I-beam, and the bolt and nut assembly or positioning cone pin is fixed to the upper flange of the I-beam by passing through the hole at the bottom of both ends of the heat shield, the second screw hole on the plate, and the first screw hole on the upper flange of the I-beam in sequence.

[0010] Preferably, the I-beam is a long strip of steel, and the cross-section of the I-beam is "I" shaped.

[0011] Preferably, the two included angles α at the bottom of the isosceles trapezoid of each positioning channel steel cross section are 45°.

[0012] Preferably, a positioning block is spot-welded to the upper flange of the I-beam near the plate. The positioning block is used to abut against the end of the heat shield above the plate, and the height of the positioning block is higher than the height of the plate.

[0013] Preferably, several positioning channel steels are evenly arranged between two I-beams and are parallel to each other.

[0014] Preferably, the ends of the arc-shaped stiffener are welded to the side of the web of the two I-beams closest to the side of the arc-shaped stiffener.

[0015] The advantages of this invention are:

[0016] 1. This invention provides a positioning device suitable for hot-screen welding. A support frame is constructed using positioning channel steel, I-beams, arc-shaped plates, arc-shaped stiffeners, and plate components, providing stable and precise positioning and support for the hot-screen. The arc of the arc-shaped stiffeners matches the inner arc of the arc-shaped plates, which in turn matches the inner arc of the hot-screen. The holes at the bottom of both ends of the hot-screen, the second screw holes on the plates, and the first screw holes on the I-beams, in conjunction with the fastening device, accurately fix the hot-screen in the designated position, effectively limiting deformation of parts during welding, ensuring the dimensional and shape accuracy of the welded parts, greatly improving welding quality, and meeting the high-precision manufacturing requirements of nuclear power products.

[0017] 2. The positioning device for hot-screen welding of this invention is relatively simple to use. Workers only need to fix the arc-shaped thin-walled parts, horizontal stiffeners, vertical stiffeners, and L-shaped bent plates to be welded onto the support frame. The positioning blocks are used to quickly adjust the position, and the alignment of each hole is checked. Then, using a staggered arrangement of bolt and nut assemblies and positioning cone pins, the positioning cone pins restrict the position of each hole. Finally, the bolts are tightened to press the hot-screen against the support frame. This operation method does not require highly skilled workers, reducing reliance on worker proficiency and making the production process easier to control and promote.

[0018] 3. This invention provides a positioning device suitable for hot-screen welding. Its rational design and precise coordination of components enable rapid positioning and assembly of hot-screen parts. During welding, priority is given to welding the intermittently welded horizontal and vertical stiffeners, creating a rigid component with the curved thin-walled part. Two welders simultaneously perform symmetrical welding to reduce deformation. Finally, the two longitudinal seams of the curved thin-walled part and the L-shaped bent plate are welded to reduce stress concentration. The method of using a wooden mallet to gently vibrate and eliminate residual welding stress effectively shortens welding time. The entire production process, from positioning and assembly to welding completion, operates efficiently, significantly improving production efficiency, and is particularly suitable for the mass production of products such as vertical shaft hot-screens.

[0019] 4. This invention provides a positioning device suitable for hot-shield welding, designed with full consideration for ease of welding operation and the removal of various positioning devices. U-shaped notches are provided on the curved stiffeners on both sides, allowing for smooth welding of the inner weld seams on both sides without obstruction by the devices. After welding, the protective devices can be easily removed without damaging the welded parts, ensuring product integrity and quality. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A front view of a positioning device suitable for hot-screen welding;

[0022] Figure 2 A top view of a positioning device suitable for hot-screen welding;

[0023] Figure 3 A side view of a positioning device suitable for hot-screen welding;

[0024] Figure 4 A schematic diagram of the structure of a welded heat shield component;

[0025] Figure 5 This is a schematic diagram of the L-shaped bent plate of the heat shield component.

[0026] In the diagram: 1. Positioning channel steel; 2. I-beam; 2001. First screw hole; 3. Positioning block; 4. Fastening device; 5. Arc-shaped plate; 6. Arc-shaped stiffener; 7. Plate; 701. Second screw hole; 801. Arc-shaped thin-walled part; 802. Horizontal stiffener part; 803. Vertical stiffener part; 804. L-shaped bent plate part; 8041. Hole position. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figure 4 and Figure 5As shown, the heat shield includes several arc-shaped thin-walled parts 801, several horizontal stiffener parts 802, and several vertical stiffener parts 803. The arc-shaped thin-walled parts 801 are welded together sequentially with their arc edges as welding surfaces. Several parallel horizontal stiffener parts 802 are uniformly welded horizontally above each arc-shaped thin-walled part 801. Several vertical stiffener parts 803 are welded vertically above each arc-shaped thin-walled part 801, and the several vertical stiffener parts 803 are welded into a straight line. A vertical stiffener part 803 is welded between two adjacent horizontal stiffener parts 802. On the heat shield welded together, in addition to the positions between adjacent horizontal stiffener parts 802, a vertical stiffener part 803 is also welded between the horizontal stiffener parts 802 and the edge of the heat shield. An L-shaped bent plate part 804 is welded to each side of the heat shield welded together. Several holes 8041 are opened at the bottom of the L-shaped bent plate part 804. When cutting L-shaped bent plate part 804, several holes 8041 are laser-cut out; assembly lines are drawn on the heat screen by laser, which are used to quickly assemble and position several heat screens, several horizontal stiffener parts 802 and several vertical stiffener parts 803.

[0029] Example 1

[0030] like Figure 1 , Figure 2 and Figure 3 As shown, a positioning device suitable for hot-screen welding includes several positioning channel steels 1, two I-beams 2, several positioning blocks 3, several fastening devices 4, and several arc-shaped stiffening plates 6. Several positioning channel steels 1 are installed between the two I-beams 2. An arc-shaped plate 5 is fixedly welded above the arc-shaped stiffening plates 6. The hot screen is placed above the arc-shaped plate 5. The hot screen is arc-shaped, and the curvature of the arc-shaped stiffening plates 6 matches the inner arc of the arc-shaped plate 5. The curvature of the arc-shaped plate 5 matches the inner arc of the hot screen. The cross-sectional shape of each positioning channel steel 1 is an isosceles trapezoid. An I-beam 2 is vertically fixed on the inclined surface of one side of several positioning channel steels 1 and welded to the lower flange of the I-beam 2. Several positioning channel steels 1 are vertically fixed on the inclined surface on the other side of another I-beam 2 and welded to the lower flange of the other I-beam 2. The two ends of the arc-shaped stiffener 6 are respectively welded to the web of the two I-beams near the upper flange. A U-shaped notch is opened at each end of the arc-shaped stiffener 6. The upper flange of the I-beam 2 is opened with a first screw hole 2001 corresponding to the hole position 8041 at the bottom of both ends of the heat shield part. The fastening device 4 passes through the hole position 8041 and is fixedly installed in the first screw hole 2001 of the upper flange of the I-beam 2. The positioning block 3 is fixedly set on the upper flange of the I-beam 2 and abuts against both ends of the heat shield. The positioning block 3 is used to position and abut against both ends of the heat shield.

[0031] The two ends of the arc-shaped plate 5 extend to the arc-shaped rib plate 6 and stop near the U-shaped notch.

[0032] A U-shaped notch is provided at each end of the arc-shaped stiffener 6 to prevent the arc-shaped stiffener 6 from being directly attached to the arc-shaped thin-walled part 801 and thus preventing welding. This allows the longitudinal weld between the arc-shaped thin-walled part 801 and the L-shaped bent plate part 804 to be successfully welded.

[0033] Example 2

[0034] like Figure 1 , Figure 2 and Figure 3 As shown, preferably, the fastening device 4 includes a bolt and nut assembly and a positioning cone pin. The bolt and nut assembly and the positioning cone pin of the fastening device 4 are arranged in a staggered manner in the first screw hole 2001 of the I-beam 2. A bolt and nut assembly is installed every three first screw holes 2001, and the positioning cone pins are installed in the remaining first screw holes 2001.

[0035] Preferably, the axis of the I-beam 2 is aligned with the normal direction of the corresponding side slope of the positioning channel steel 1, and the included angle between them is 90°.

[0036] Preferably, a plate 7 is spot-welded to the upper flange of each of the I-beams 2. The plate 7 has a second screw hole 701 corresponding to the hole 8041 at the bottom of both ends of the heat shield. The plate 7 is disposed between the end of the heat shield and the I-beam 2. The bolt and nut assembly or the positioning cone pin passes through the hole 8041 at the bottom of both ends of the heat shield, the second screw hole 701 on the plate 7 and the first screw hole 2001 on the upper flange of the I-beam 2 in sequence and is fixed to the upper flange of the I-beam 2.

[0037] The second screw hole on the mounting plate is coaxial with the first screw hole on the upper flange of the I-beam and the hole on the heat shield component.

[0038] The first screw hole 2001 on the upper flange of the I-beam 2 and the second screw hole 701 on the mounting plate 7 are consistent with the hole 8041 at the bottom of the L-shaped bent plate part 804. The hole spacing of the hot screen can be ensured by the fastening device 4. The curvature of the arc-shaped mounting plate 5 is consistent with the curvature of the arc-shaped thin-walled part 801. The curvature of the hot screen can be guaranteed when the plates are in place.

[0039] The product's heat shield is fixed to a positioning device suitable for heat shield welding via a fastening device 4, secured by a bolt and nut assembly, and positioned by a positioning cone pin. After welding and cooling, the heat shield has a certain rigidity. The positioning device can be quickly disengaged by disassembling the bolt and nut assembly and the positioning cone pin in sections. The positioning cone pin has a certain taper, which will not damage the welded parts. This ensures the integrity and quality of the product.

[0040] Preferably, the I-beam 2 is a long strip of steel, and the cross-section of the I-beam 2 is "I" shaped.

[0041] Preferably, the two included angles α at the bottom of the isosceles trapezoid of the cross section of each of the positioning channel steel 1 are 45°.

[0042] Preferably, a positioning block 3 is spot-welded to the upper flange of the I-beam 2 near the position of the mounting plate 7. The positioning block 3 is used to abut against the end of the heat shield above the mounting plate 7, and the height of the positioning block 3 is higher than the height of the mounting plate 7.

[0043] Preferably, a plurality of the positioning channel steels 1 are evenly arranged between two I-beams 2 and are parallel to each other.

[0044] Preferably, the ends of the arc-shaped stiffener 6 are welded to the side of the web of the two I-beams 2 closest to the side of the arc-shaped stiffener 6.

[0045] The bottom of the L-shaped bent plate part 804 of the heat shield has several holes 8041, and the arc-shaped thin-walled part 801 is placed on top of the arc-shaped plate 5.

[0046] Several positioning channel steels 1, two I-beams 2, several arc-shaped stiffening plates 6, and a mounting plate 7 are welded together to form a support frame, which is used to realize the rapid welding of heat shield parts, position the heat shield parts, and protect the heat shield parts from deformation during the welding process.

[0047] Example 3

[0048] The assembly process of a positioning device suitable for hot-screen welding is as follows:

[0049] Positioning channel steel 1, I-beam 2, curved plate 5, curved stiffener 6, and plate 7 are welded together to form a supporting frame. The two I-beams 2 have 39 first screw holes 2001 at the same positions as the openings in the L-shaped bent plate part 804. The two I-beams 2 are welded perpendicularly to both sides of the positioning channel steel 1. Each side of the I-beam 2 has 39 first screw holes 2001. Plate 7 is spot-welded to the upper flange of the I-beam 2 to prevent contamination of the product material. Positioning block 3 is located next to plate 7 on the I-beam 2. The upper flange is spot-welded and fixed. The positioning block is made of stainless steel plate with a size of 30*30*5mm. The fastening device 4 is a bolt and nut assembly and a positioning cone pin. The arc-shaped plate 5 is an arc-shaped plate. The curvature of the arc-shaped plate 5 is consistent with the inner arc of the arc-shaped thin-walled part 801. The arc-shaped stiffener 6 supports the arc-shaped plate 5. The arc-shaped stiffener 6 has U-shaped notches on both sides. The size of the U-shaped notches is 60mm in length and 30mm in width, which can ensure that the arc-shaped thin-walled part and the L-shaped bent plate part can be welded smoothly.

[0050] A positioning device suitable for hot-screen welding is applied to the welding operation method of hot-screen parts as follows:

[0051] a. First, place the arc-shaped thin-walled part 801 on the arc-shaped plate 5 of the support frame;

[0052] b. Then place the L-shaped bending plate part 804 on the plate 7 on the upper flange of the I-beam 2, quickly adjust the position by using the positioning block 3, check whether each hole is aligned, and position it by using the fastening device 4. The bolt and nut assembly and the positioning cone pin are arranged in a staggered manner. A bolt and nut assembly is installed every 3 holes, and the position of each hole is restricted by the positioning cone pin.

[0053] c. Adjust the relative positions of the arc-shaped thin-walled part 801 and the L-shaped bent plate part 804, and fix them initially;

[0054] d. Arrange the horizontal stiffener plate parts 802 according to the marked positions of the arc-shaped thin-walled parts 801 and spot weld them in place;

[0055] e. Place the vertical stiffener plate parts 803 in each interval in sequence and adjust their positions;

[0056] f. Perform spot welding to fix all positions;

[0057] g. Begin overall welding. Prioritize welding the intermittently welded horizontal stiffener plate part 802 and vertical stiffener plate part 803 to form a component with better rigidity with the arc-shaped thin-walled part 801. The welding process is carried out by two welders simultaneously and symmetrically to reduce welding deformation. Finally, weld the two longitudinal seams of the arc-shaped thin-walled part 801 and the L-shaped bent plate part 804 to reduce welding stress concentration.

[0058] During welding, a wooden mallet is used for vibration stress relief, employing intermittent tapping at a frequency of 2-5 Hz. After the workpiece has naturally cooled to room temperature, the support frame constraint is removed. Welding is performed in a skip-sequence manner to ensure no localized overheating, followed by slow cooling at high temperatures after welding. A preliminary dimensional inspection is conducted before removing the lower support frame constraint, and complete disassembly is only performed after the inspection confirms that the workpiece passes inspection.

[0059] This invention discloses a positioning device suitable for hot-screen welding. A support frame is constructed using positioning channel steel, I-beams, arc-shaped plates, arc-shaped stiffeners, and plate components, providing stable and precise positioning and support for the hot-screen. It enables rapid positioning and assembly of hot-screen components. During welding, the horizontal and vertical stiffeners are welded intermittently to create a rigid component with the arc-shaped thin-walled part. Two welders simultaneously perform symmetrical welding to reduce deformation. Finally, the two longitudinal seams between the arc-shaped thin-walled part and the L-shaped bent plate are welded to reduce stress concentration. The method of using a wooden mallet to gently vibrate and eliminate residual welding stress effectively shortens the welding time. This positioning device prevents deformation of the hot-screen during welding and its design also fully considers the convenience of welding operations and the ease of removing the positioning components.

[0060] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0061] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A positioning device suitable for heat shield welding, characterized in that, The device includes several positioning channel steels (1), two I-beams (2), several positioning blocks (3), several fastening devices (4), and several arc-shaped stiffeners (6). Several positioning channel steels (1) are installed between the two I-beams (2). An arc-shaped plate (5) is fixedly welded above the arc-shaped stiffener (6). A heat screen is placed above the arc-shaped plate (5). The heat screen is arc-shaped. The curvature of the arc-shaped stiffener (6) is consistent with the inner arc of the arc-shaped plate (5). The curvature of the arc-shaped plate (5) is consistent with the inner arc of the heat screen. The cross-sectional shape of each positioning channel steel (1) is an isosceles trapezoid. An I-beam (2) is vertically fixed on the inclined surface of one side of several positioning channel steels (1) and welded to the lower flange of the I-beam (2). (1) Another I-beam (2) is vertically fixed on the inclined surface on the other side and welded to the lower flange of the other I-beam (2). The two ends of the arc-shaped stiffener (6) are respectively welded to the web of the two I-beams (2) near the upper flange. A U-shaped notch is opened at each end of the arc-shaped stiffener (6). The upper flange of the I-beam (2) is opened with a first screw hole (2001) corresponding to the hole (8041) at the bottom of both ends of the heat screen. The fastening device (4) passes through the hole (8041) and is fixedly installed in the first screw hole (2001) of the upper flange of the I-beam (2). The positioning block (3) is fixedly set on the upper flange of the I-beam (2) and abuts against both ends of the heat screen. The positioning block (3) is used to position and abut against both ends of the heat screen.

2. A positioning device suitable for heat shield welding according to claim 1, characterized in that The fastening device (4) includes a bolt and nut assembly and a positioning cone pin. The bolt and nut assembly and the positioning cone pin of the fastening device (4) are arranged in a staggered manner in the first screw hole (2001) of the I-beam (2). A bolt and nut assembly is installed every three first screw holes (2001), and the positioning cone pin is installed in the remaining first screw holes (2001).

3. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, The axis of the I-beam (2) is aligned with the normal direction of the corresponding side slope of the positioning channel (1), and the included angle between them is 90°.

4. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, Each of the I-beams (2) has a spot-welded plate (7) on its upper flange. The plate (7) has a second screw hole (701) corresponding to the hole (8041) at the bottom of both ends of the heat screen. The plate (7) is placed between the end of the heat screen and the I-beam (2). The bolt and nut assembly or the positioning cone pin passes through the hole (8041) at the bottom of both ends of the heat screen, the second screw hole (701) on the plate (7), and the first screw hole (2001) on the upper flange of the I-beam (2) in sequence and is fixed to the upper flange of the I-beam (2).

5. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, The I-beam (2) is a long strip of steel, and the cross-section of the I-beam (2) is "I" shaped.

6. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, The two included angles α under the isosceles trapezoidal base of the cross section of each of the positioning channel steels (1) are 45°.

7. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, The positioning block (3) is spot-welded at the position of the upper flange of the I-beam (2) near the plate (7). The positioning block (3) is used to hold the end of the heat shield above the plate (7). The height of the positioning block (3) is higher than the height of the plate (7).

8. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, Several positioning channel steels (1) are evenly arranged and parallel to each other between two I-beams (2).

9. A positioning device suitable for hot-screen welding according to claim 1, characterized in that, The two ends of the arc-shaped stiffener (6) are welded to the side of the web of the two I-beams (2) near the side of the arc-shaped stiffener (6).

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