A large heat exchanger welding mechanism

Abstract

The utility model discloses a kind of welding mechanism of large heat exchanger, including main casing, the middle part of left side plate and right side plate of main casing is shaped with moving through slot;The left part and right part between the front and rear two side plates of main casing are fixed with connecting beam, the middle part outer side wall of two connecting beams is fixed with side pressing cylinder, the end of push rod of side pressing cylinder stretches out the inner side wall of corresponding connecting beam and is fixed for pressing the pressing plate of heat exchanger;The top surface of two connecting beams is equipped with welding head moving mechanism, and the welding head of welding head moving mechanism is welded to the upper portion U-shaped head of heat exchanger with up and down, before and after and rotation angle.It can be automatically welded, and its effect is good, efficiency is high, and every welding head is separately controlled, corresponding welding head can be opened according to need, realize accurate welding, improve welding quality.

Description

Technical Field

[0001] This utility model relates to the technical field of large heat exchanger processing equipment, and more specifically to a large heat exchanger welding mechanism. Background Technology

[0002] Existing large heat exchangers typically reach a height of 2.8m and a span of approximately 0.8m. These heat exchangers generally consist of multiple vertical heat exchange tubes housed within multiple heat dissipation fins. Then, the two ends of a U-shaped bend are inserted into the ends of two corresponding vertical heat exchange tubes to connect them. For example, in a large integrated heat exchanger for supermarkets (Chinese patent application number 202021105833.1), both ends of the vertical heat exchange tubes need to be connected via U-shaped bends. This requires manual insertion of the U-shaped bends into the ends of the corresponding vertical heat exchange tubes before transporting them to a tunnel furnace for brazing. However, conventional tunnel furnaces cannot handle the transport of large heat exchangers. Brazing can only be achieved manually by spraying flames onto the connection points to melt the flux and solder at the corresponding locations. This method is labor-intensive, inefficient, and yields poor results. Utility Model Content

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a welding mechanism for large heat exchangers. It can be installed on the conveying mechanism of the heat exchanger and automatically welded after being moved into the main shell of the heat exchanger. It has good effect, high efficiency and greatly reduces the amount of manual labor.

[0004] The solution of this utility model to the aforementioned technical problem is: A welding mechanism for a large heat exchanger includes a main shell, wherein a movable through groove is formed in the middle of the left side plate and the right side plate of the main shell. A connecting beam is fixed between the left and right sides of the front and rear side plates of the main housing; The top surfaces of the two connecting beams are equipped with welding head moving mechanisms. The welding heads of the welding head moving mechanisms move up and down, back and forth, and rotate to weld the upper U-shaped head of the heat exchanger.

[0005] An upper horizontal fixing plate is fixed on the upper inner side wall of the main housing. Guide rails are fixed on the front and rear of the top surface of the connecting beam. Guide rails are also fixed on the bottom surface of the corresponding upper horizontal fixing plate. The moving frame is located between the corresponding connecting beam and the upper horizontal fixing plate. A vertical fixing plate is fixed between the front of the corresponding connecting beam and the upper horizontal fixing plate. A moving cylinder is fixed in the middle of the front side wall of the vertical fixing plate. The rear end of the push rod of the moving cylinder extends out of the rear wall of the corresponding vertical fixing plate and is fixed on the moving frame. The upper and lower fixed sliders of the moving frame are inserted into the corresponding guide rails and cooperate with the guide rails.

[0006] The movable frame includes a central horizontal fixed plate, and vertical movable plates are fixed to the front and rear left and right sides of the central horizontal fixed plate. Slider blocks are fixed to the top and bottom of the vertical movable plates. Horizontal fixing plates are fixed on the inner sidewalls of the middle and lower parts of the vertical moving plate. The two ends of the vertical adjusting screw are movably connected to the two horizontal fixing plates through bearings. An adjusting motor is fixed on the bottom surface of the lower horizontal fixing plate. The adjusting motor drives the vertical adjusting screw to rotate. The lifting adjusting block is screwed onto the corresponding vertical adjusting screw. A side slider is fixed on one side wall of the lifting adjusting block. A vertical guide rail is fixed on the inner side wall of the corresponding vertical moving plate. The side slider is inserted into and cooperates with the corresponding vertical guide rail. A fixing beam is fixed between the two corresponding lifting adjusting blocks.

[0007] A transverse plate is fixed to the bottom of the front and rear parts of the outer side of the fixed beam. An electric cylinder is fixed to each transverse plate. The end of the push rod of the electric cylinder on the same side extends out of the corresponding fixed beam and fixes the push beam. An end plate is fixed to the inner wall of the front and rear parts of the push beam. The rotating shaft is movably connected to the two end plates through bearings. One end of the rotating shaft extends out of the corresponding end plate and is fixed with a transmission gear. A rotary adjustment servo motor is fixed to the upper part of the corresponding end plate. The end of the output shaft of the rotary adjustment servo motor extends out of the corresponding end plate and is fixed with a drive gear. The drive gear meshes with the transmission gear. A transverse connecting block is fixed in the middle of the rotating shaft, and multiple welded vent shells are fixed on the bottom surface of the transverse connecting block. Welding heads are installed on the side of the welded vent shells facing the heat exchanger.

[0008] The top surface of the middle horizontal fixed plate is formed with a transverse through groove extending forward and backward. A middle moving frame is provided at the top surface of the middle horizontal fixed plate. The bottom of the legs at the left and right sides of the middle moving frame are fixed with sliders. The sliders are inserted into and cooperate with the guide rails fixed at the left and right sides of the top surface of the middle horizontal fixed plate. A fixed plate is fixed on the top surface of the middle horizontal fixed plate at the front of the transverse through groove. A second push cylinder is fixed on the front side wall of the fixed plate. The end of the push rod of the second push cylinder extends out of the rear wall of the fixed plate and is fixed to a vertical plate fixed on the front side wall of the middle moving frame. A lifting cylinder is fixed in the middle of the top surface of the top plate of the middle moving frame. The bottom end of the push rod of the lifting cylinder extends out of the bottom surface of the top plate of the middle moving frame and the bottom surface of the transverse through groove and is fixed with a horizontal plate. A cooling plate is provided below the horizontal plate, and the cooling plate faces the top of the upper U-shaped head of the heat exchanger.

[0009] Multiple vertical guide screws are fixed on the top surface of the cooling plate. A buffer spring is inserted into the vertical guide screw. The top of the vertical guide screw extends out of the top of the corresponding through hole of the horizontal plate and is screwed with a limit nut. The bottom surface of the limit nut presses against the top surface of the horizontal plate. The top of the buffer spring applies force to the bottom surface of the horizontal plate and the bottom end applies force to the top surface of the cooling plate.

[0010] Multiple laser rangefinders arranged in a left-right pattern are fixed to the bottom surface of the rear part of the horizontal fixed plate. The laser rangefinders illuminate the upper U-shaped head of the heat exchanger below.

[0011] An exhaust fan is fixed at the top of the main housing, and the exhaust fan's outlet faces the air outlet hole in the middle of the top of the main housing.

[0012] The outstanding effect of this utility model is: Compared with existing technologies, it can be installed on the conveying mechanism of the heat exchanger. After moving to the main shell through the heat exchanger, it can perform automatic welding. It has good effect, high efficiency, and greatly reduces manual labor. Moreover, each welding head is individually controlled, and the corresponding welding head can be opened as needed to achieve precise welding and improve welding quality. Attached Figure Description

[0013] Figure 1 This is a partial structural schematic diagram of the present invention; Figure 2 yes Figure 1 A magnified view of a portion of the image; Figure 3 yes Figure 2 A magnified view of a portion of the image; Figure 4 This is a partial structural diagram of the angle-changing part of this utility model; Figure 5 yes Figure 4 A magnified view of a portion of the image; Figure 6 This is a partial cross-sectional view of the cooling plate. Detailed Implementation

[0014] For example, see below. Figures 1 to 6 As shown, a welding mechanism for a large heat exchanger includes a main shell 10. The middle of the left and right side plates of the main shell 10 are formed with movable channels. Transverse rods extend into the left and right parts of the movable channels. The two transverse rods of the main shell 10 are located at the middle of the left and right sides of the heat exchanger 100 being transported in the middle, to prevent it from tipping over.

[0015] A connecting beam 11 is fixed between the left and right parts of the front and rear side plates of the main housing 10; An upper horizontal fixing plate 14 is fixed on the upper inner side wall of the main housing 11; The top surfaces of the two connecting beams 11 are equipped with welding head moving mechanisms.

[0016] The welding head moving mechanism is as follows: guide rails are fixed to the front and rear of the top surface of the connecting beam 11, and guide rails are also fixed to the bottom surface of the corresponding upper horizontal fixed plate 14. The moving frame 16 is located between the corresponding connecting beam 11 and the upper horizontal fixed plate 14. A vertical fixed plate 15 is fixed between the front of the corresponding connecting beam 11 and the upper horizontal fixed plate 14. A moving cylinder 151 is fixed to the middle of the front side wall of the vertical fixed plate 15. The rear end of the push rod of the moving cylinder 151 extends out of the rear wall of the corresponding vertical fixed plate 15 and is fixed on the corresponding vertical moving plate 162 at the front of the moving frame 16. The upper and lower fixed sliders of the moving frame 16 are inserted into the corresponding guide rails and cooperate with the guide rails.

[0017] Furthermore, the movable frame 16 includes a central horizontal fixed plate 161, and vertical movable plates 162 are fixed to the left and right sides of the front and rear sides of the central horizontal fixed plate 161, and sliders are fixed to the top and bottom of the vertical movable plates 162. Horizontal fixing plates are fixed on the inner sidewalls of the middle and lower parts of the vertical moving plate 162. The two ends of the vertical adjusting screw 163 are movably connected to the two horizontal fixing plates through bearings. An adjusting motor 164 is fixed on the bottom surface of the lower horizontal fixing plate. The output shaft of the adjusting motor 164 is a spline shaft, which is inserted into the spline hole at the bottom end of the vertical adjusting screw 163 and drives the vertical adjusting screw 163 to rotate. The lifting adjusting block 165 is screwed onto the corresponding vertical adjusting screw 163. A side slider is fixed on one side wall of the lifting adjusting block 165. A vertical guide rail is fixed on the inner sidewall of the corresponding vertical moving plate 162. The side slider is inserted into the corresponding vertical guide rail and cooperates with it. A fixing beam 166 is fixed between the two corresponding lifting adjusting blocks 165.

[0018] Furthermore, a transverse plate is fixed to the bottom of the front and rear parts of the outer side of the fixed beam 166, and an electric cylinder 167 is fixed to each transverse plate. The end of the push rod of the electric cylinder 167 on the same side extends out of the corresponding fixed beam 166 and fixes the push beam 168. An end plate is fixed to the inner wall of the front and rear parts of the push beam 168. The rotating shaft 169 is movably connected to the two end plates through bearings. One end of the rotating shaft 169 extends out of the corresponding end plate and is fixed with a transmission gear 1691. A rotary adjustment servo motor 1692 is fixed to the upper part of the corresponding end plate. The end of the output shaft of the rotary adjustment servo motor 1692 extends out of the corresponding end plate and is fixed with a drive gear 1693. The drive gear 1693 meshes with the transmission gear 1691. A transverse connecting block 1694 is fixed in the middle of the rotating shaft 169. A plurality of welding vent housings 17 are fixed on the bottom surface of the transverse connecting block 1694. Welding heads are installed on the side of the welding vent housing 17 facing the heat exchanger 100. Fuel in the welding vent housing 17 is supplied to the welding head. The welding vent housing 17 is connected to the discharge pipe of the fuel conveying equipment through a connecting pipe. Fuel is supplied through the fuel conveying equipment, which is a conventional structure and will not be described in detail here.

[0019] Furthermore, guide rods are fixed to the front and rear of the outer wall of the pushing beam 168, and the guide rods are inserted into the corresponding guide through holes of the fixed beam 166 and cooperate with the guide through holes.

[0020] Furthermore, the transverse connecting block 1694 has an axially extending limiting protrusion 1695 fixed on one side wall of the pushing beam 168, and an axial limiting block 1681 fixed on the lower inner wall of the pushing beam 168 below it. The axially extending limiting protrusion 1695 and the welded vent housing 17 correspond to the axial limiting block 1681.

[0021] Furthermore, the central horizontal fixing plate 161 has a transverse through groove 18 extending forward and backward on its central top surface. A central movable frame 181 is provided at the central top surface of the central horizontal fixing plate 161. Slider blocks are fixed to the bottom of the legs at the left and right sides of the central movable frame 181. The sliders are inserted into and cooperate with guide rails fixed at the left and right sides of the top surface of the central horizontal fixing plate 161. A fixing plate is fixed to the top surface of the central horizontal fixing plate 161 at the front of the transverse through groove 18. A second [unclear - possibly a component or element] is fixed to the front side wall of the fixing plate. The push rod of the second push cylinder 182 extends out of the rear wall of the fixed plate and is fixed to a vertical plate fixed on the front side wall of the middle moving frame 181. A lifting cylinder 183 is fixed in the middle of the top surface of the top plate of the middle moving frame 181. The bottom end of the push rod of the lifting cylinder 183 extends out of the bottom surface of the top plate of the middle moving frame 181 and the bottom surface of the transverse through groove 18 and is fixed to a horizontal plate 184. A cooling plate 185 is provided below the horizontal plate 184, and the cooling plate 185 faces the top of the upper U-shaped head of the heat exchanger 100.

[0022] Furthermore, a plurality of vertical guide screws 186 are fixed on the top surface of the cooling plate 185. A buffer spring 187 is inserted into the vertical guide screw 186. The top of the vertical guide screw 186 extends out of the top of the corresponding through hole of the horizontal plate 184 and is screwed with a limit nut 188. The bottom surface of the limit nut 188 presses against the top surface of the horizontal plate 184. The top of the buffer spring 187 applies force to the bottom surface of the horizontal plate 184 and the bottom end applies force to the top surface of the cooling plate 185.

[0023] Furthermore, the top surface of the horizontal plate 184 is fixed with a plurality of guide rods, which are inserted into guide through holes formed on the top plate of the central movable frame 181 and cooperate with the guide through holes. Multiple laser rangefinders 19 arranged in a left-right arrangement are fixed on the bottom surface of the rear part of the horizontal fixing plate 161. The laser rangefinders 19 illuminate the upper U-shaped head of the heat exchanger 100 below.

[0024] Furthermore, an exhaust fan 191 is fixed at the top of the main housing 10, and the air outlet of the exhaust fan 191 faces the air outlet hole in the middle of the top of the main housing 10. By operating the exhaust fan 191, hot air in the main housing 10 can be discharged to the outside.

[0025] Furthermore, the cooling plate 185 has a cooling cavity formed inside, and multiple front-to-back extending partition plates are provided in the cooling cavity. The top and bottom surfaces of the partition plates are welded and fixed to the top and bottom surfaces of the cooling cavity. A water inlet connector is connected to the rear side wall of the cooling plate 185, and a water outlet connector is connected to the front wall of the cooling plate 185. The water inlet connector is connected to the outlet pipe of an external liquid cooling circulation system through a connecting pipe, and the water outlet connector is connected to the inlet pipe of an external liquid cooling circulation system, thereby realizing the circulation of water. The liquid cooling circulation system can be a product that can be directly purchased from the market, which is a conventional structure and will not be described in detail here.

[0026] In this embodiment, all cylinders are connected to the corresponding control valves of the pneumatic system via connecting pipes. The control valves are used to activate the corresponding cylinders. All electrical components of the pneumatic system and all electrical components of this embodiment are electrically connected to the control host via electrical connection lines. The operation is controlled by the control host. This is a conventional structure and will not be described in detail here.

[0027] In this embodiment, it is installed at the conveying equipment. The conveying equipment can be a conventional conveying device or other conveying devices (in this embodiment, it is a conventional double-speed chain conveyor line, which will not be described in detail here). It places the vertically placed heat exchanger 100 in the bottom moving seat and conveys it from front to back. When it enters the main housing 10, the limit switch installed at the double-speed chain conveyor line senses the bottom moving seat of the heat exchanger 100 and stops the conveying. The bottom moving seat can be fixed by the positioning mechanism at the bottom (it can be done by fixing the push cylinder at the corresponding position of the double-speed chain conveyor line and inserting the positioning rod fixed at the end of the push rod into the corresponding insertion hole on the top surface of the bottom moving seat, or other methods can be used, which will not be described in detail here). At the same time, the sensing signal is sent to the control host to confirm that the heat exchanger 100 has moved into place. Simultaneously, during the conveying process of heat exchanger 100, all the laser rangefinders 19 above it will detect the laser line illuminating the top of heat exchanger 100 below. Some of the laser rangefinders 19 will illuminate the very top of the corresponding upper U-shaped head. The value with the shortest distance among all detected values ​​is the measured value. This value is then transmitted to the control host, which controls the corresponding regulating motor 164 to operate, causing all welding heads on both sides to descend, aligning with the connection point between the upper U-shaped head and the top of the vertical tube at the top of heat exchanger 100. Meanwhile, a central fixing plate is fixed to the top surface of the middle of the two connecting beams 11, and a central laser rangefinder 19 is fixed to each of these plates. This sensor illuminates the left or right side wall of heat exchanger 100 with its laser line, measuring the distance and transmitting the detection signal to the control host. The control host then controls the push rod of the corresponding electric cylinder 167 to push the welding head closer to the connection point between the upper U-shaped head and the top of the vertical tube at the top of heat exchanger 100, and then sprays flame. The welding head is brazed (in this embodiment, the automatic igniters at all welding heads are electrically connected to the control host via electrical connection lines, and can be controlled independently. They can automatically ignite the corresponding welding heads as needed, that is, only the welding heads that need to be ignited can be turned on as needed, thereby greatly improving welding accuracy and welding quality). During this process, the rotation of the shaft of the servo motor 1692 is adjusted to achieve a certain angle of rotation (it is a servo motor, so its rotation angle is set by the control host, for example, 30° to 60° forward and reverse rotation). The welding head is rotated at a certain angle (the axially extended limiting protrusion 1695 and the welding vent housing 17 correspond to the axial limiting block 1681, which can prevent it from rotating uncontrollably. The axial limiting block 1681 rests on the limiting protrusion 1695 or the welding vent housing 17 to achieve forward and reverse rotation limitation). The welding head is moved back and forth horizontally by pushing or retracting the push rod of the moving cylinder 151, realizing multi-directional welding action and ensuring welding effect. Meanwhile, during the welding process, the push rod of the second push cylinder 182 pushes the cooling plate 185 backward. At this time, it will block the laser range sensor 19 above. However, the laser line of the laser range sensor 19 is blocked. The measured value is transmitted to the control host, but the control host will not process it. Then, the push rod of the lifting cylinder 183 pushes the bottom surface of the cooling plate 185 against the top of all the upper U-shaped heads. This allows the excess heat during the welding process to exchange heat with the liquid flowing in the cooling plate 185, thereby cooling down and preventing overheating that could deform or melt the upper U-shaped heads.

[0028] After heat exchange in the cooling plate 185, the liquid flows back to the liquid cooling circulation system, where it can exchange heat through the refrigeration device inside (such as a refrigeration device consisting of a compressor, evaporator, condenser, etc., which can be installed inside the cooling plate 185; the liquid enters the water tank with the evaporator to exchange heat with it and achieve cooling, and then flows out to the cooling plate 185 for heat exchange again. This is the conventional method and will not be described in detail here). After a certain period of welding, all components return to their original positions. The welded heat exchanger 100 can be transported backward by the conveying equipment and removed from the main shell 10, which is very convenient.

[0029] The above embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present utility model. Therefore, all equivalent technical solutions also fall within the scope of the present utility model, and the patent protection scope of the present utility model should be defined by the claims.

Claims

1. A welding mechanism for a large heat exchanger, comprising a main shell (10), characterized in that: The left and right side plates of the main housing (10) are both formed with movable through grooves in the middle. A connecting beam (11) is fixed between the left and right sides of the front and rear side plates of the main housing (10). The top surfaces of the two connecting beams (11) are equipped with welding head moving mechanisms. The welding head of the welding head moving mechanism moves up and down, forward and backward, and rotates to weld the upper U-shaped head of the heat exchanger (100).

2. The welding mechanism for a large heat exchanger according to claim 1, characterized in that: An upper horizontal fixing plate (14) is fixed on the upper inner side wall of the main housing (10). The welding head moving mechanism is as follows: the front and rear parts of the top surface of the connecting beam (11) are fixed with guide rails, and the bottom surface of the corresponding upper horizontal fixed plate (14) is also fixed with guide rails. The moving frame (16) is located between the corresponding connecting beam (11) and the upper horizontal fixed plate (14). A vertical fixed plate (15) is fixed between the front parts of the corresponding connecting beam (11) and the upper horizontal fixed plate (14). A moving cylinder (151) is fixed in the middle of the front side wall of the vertical fixed plate (15). The rear end of the push rod of the moving cylinder (151) extends out of the rear wall of the corresponding vertical fixed plate (15) and is fixed on the corresponding vertical moving plate (162) at the front of the moving frame (16). The upper and lower fixed sliders of the moving frame (16) are inserted into the corresponding guide rails and cooperate with the guide rails.

3. The welding mechanism for a large heat exchanger according to claim 2, characterized in that: The movable frame (16) includes a central horizontal fixed plate (161), and vertical movable plates (162) are fixed on the left and right sides of the front and rear sides of the central horizontal fixed plate (161). Slider blocks are fixed on the top and bottom of the vertical movable plates (162). The middle and lower inner walls of the vertical moving plate (162) are fixed with horizontal fixing plates. The two ends of the vertical adjusting screw (163) are movably connected to the two horizontal fixing plates through bearings. The bottom surface of the lower horizontal fixing plate is fixed with an adjusting motor (164). The adjusting motor (164) drives the vertical adjusting screw (163) to rotate. The lifting adjusting block (165) is screwed onto the corresponding vertical adjusting screw (163). A side slider is fixed on one side wall of the lifting adjusting block (165). A vertical guide rail is fixed on the inner wall of the corresponding vertical moving plate (162). The side slider is inserted into the corresponding vertical guide rail and cooperates with it. A fixing beam (166) is fixed between the two corresponding lifting adjusting blocks (165) at the front and rear.

4. The welding mechanism for a large heat exchanger according to claim 3, characterized in that: A transverse plate is fixed to the bottom of the front and rear parts of the outer side of the fixed beam (166), and an electric cylinder (167) is fixed to each transverse plate. The end of the push rod of the electric cylinder (167) on the same side extends out of the corresponding fixed beam (166) and fixes the push beam (168). An end plate is fixed to the inner wall of the front and rear parts of the push beam (168). A rotating shaft (169) is movably connected to the two end plates through a bearing. One end of the rotating shaft (169) extends out of the corresponding end plate and is fixed with a transmission gear (1691). A rotary adjustment servo motor (1692) is fixed to the upper part of the corresponding end plate. The end of the output shaft of the rotary adjustment servo motor (1692) extends out of the corresponding end plate and is fixed with a drive gear (1693). The drive gear (1693) meshes with the transmission gear (1691). A transverse connecting block (1694) is fixed in the middle of the rotating shaft (169), and a plurality of welded vent housings (17) are fixed on the bottom surface of the transverse connecting block (1694). Welding heads are installed on the side of the welded vent housing (17) facing the heat exchanger (100).

5. A welding mechanism for a large heat exchanger according to claim 4, characterized in that: Guide rods are fixed to the front and rear of the outer wall of the push beam (168). The guide rods are inserted into the corresponding guide holes of the fixed beam (166) and cooperate with the guide holes.

6. The welding mechanism for a large heat exchanger according to claim 4, characterized in that: The transverse connecting block (1694) has an axially extending limiting protrusion (1695) fixed on one side wall of the push beam (168), and an axial limiting block (1681) is fixed on the lower inner wall of the push beam (168) below it. The axially extending limiting protrusion (1695) and the welded vent housing (17) correspond to the axial limiting block (1681).

7. A welding mechanism for a large heat exchanger according to claim 4, characterized in that: The central horizontal fixing plate (161) has a transverse through groove (18) extending forward and backward on its central top surface. A central moving frame (181) is provided at the central top surface of the central horizontal fixing plate (161). Slider blocks are fixed at the bottom of the legs at the left and right sides of the central moving frame (181). The sliders are inserted into and cooperate with the guide rails fixed at the left and right sides of the top surface of the central horizontal fixing plate (161). A fixing plate is fixed on the top surface of the central horizontal fixing plate (161) at the front of the transverse through groove (18). A second push cylinder (182) is fixed on the front side wall of the fixing plate. The end of the push rod of the second push cylinder (182) extends out of the rear wall of the fixed plate and is fixed on the vertical plate fixed on the front side wall of the middle moving frame (181). The top surface of the top plate of the middle moving frame (181) is fixed with a lifting cylinder (183). The bottom end of the push rod of the lifting cylinder (183) extends out of the bottom surface of the top plate of the middle moving frame (181) and the bottom surface of the transverse through groove (18) and is fixed with a horizontal plate (184). A cooling plate (185) is provided below the horizontal plate (184). The cooling plate (185) faces the top of the upper U-shaped head of the heat exchanger (100).

8. A welding mechanism for a large heat exchanger according to claim 7, characterized in that: Multiple vertical guide screws (186) are fixed on the top surface of the cooling plate (185). A buffer spring (187) is inserted into the vertical guide screw (186). The top of the vertical guide screw (186) extends out of the top of the corresponding through hole of the horizontal plate (184) and is screwed with a limit nut (188). The bottom surface of the limit nut (188) presses against the top surface of the horizontal plate (184). The top of the buffer spring (187) applies force to the bottom surface of the horizontal plate (184) and the bottom end applies force to the top surface of the cooling plate (185).

9. A welding mechanism for a large heat exchanger according to claim 8, characterized in that: The top surface of the horizontal plate (184) is fixed with a plurality of guide rods, which are inserted into guide through holes formed on the top plate of the central movable frame (181) and cooperate with the guide through holes. Multiple laser rangefinders (19) arranged in a left-right arrangement are fixed on the bottom surface of the rear part of the middle horizontal fixing plate (161). The laser rangefinders (19) illuminate the upper U-shaped head of the heat exchanger (100) below. An exhaust fan (191) is fixed at the top of the main housing (10), and the air outlet of the exhaust fan (191) faces the air outlet hole in the middle of the top of the main housing (10).

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