Shell-less heat exchanger welded junction sealing performance detection device and detection method

Abstract

The invention relates to the technical field of sealing performance detection devices, in particular to a shell-free heat exchanger welded junction sealing performance detection device and method.The shell-free heat exchanger welded junction sealing performance detection device comprises a negative pressure cylinder, a protective shell, a helium detector body, a negative pressure mechanism and a non-return mechanism, one end of the negative pressure cylinder is attached to a welding seam of a heat exchange tube and a plate tube, and the other end of the negative pressure cylinder is fixed to the protective shell; the one-by-one helium leak detection test is carried out on a heat exchange tube and tube plate welding joint by using a vacuum box method in which a vacuum condition is established by using a negative pressure cylinder, so that not only can vacuum adjustment required during detection be quickly met, but also detection can be quickly completed, the working efficiency of detection is effectively improved, meanwhile, the accuracy is also improved, and the detection efficiency is improved. Meanwhile, the detection method is short in time consumption, vacuum adjustment needed by detection can be rapidly achieved, operation is easy, and air in a cavity, close to one side of a welding seam, in a negative pressure cylinder can be rapidly pumped out by means of reciprocating motion of an air pumping disc in a negative pressure mechanism in combination with a non-return mechanism.

Description

Technical Field

[0001] The present application relates to the technical field of sealing detection devices, and in particular to a welding sealing detection device and a detection method for a shellless heat exchanger. Background Art

[0002] The LOT130Af system condenser (1 / 2ASP1210 / 2210 / 3210CS) product manufactured by our company for the Sanao project requires a helium leak test to be carried out after the heat exchange tubes are welded to the tube sheet but before expansion according to the requirements of BJX45160407DPCH44DS "Technical Conditions for Leakage Inspection of Tube and Tube Sheet Welds of RCC-M 2 and 3 Level Shell and Tube Heat Exchangers". This technical condition stipulates two methods: the aspiration probe technology and the tracer probe technology, but also allows manufacturers to use other helium mass spectrometry leak detection methods.

[0003] According to the requirements of BJX45160407DPCH44DS "Technical Conditions for Leakage Inspection of Tube and Tube Sheet Welds of RCC-M 2, 3-Level Shell and Tube Heat Exchangers", both the suction probe technical method and the tracer probe technical method require the shell side to be vacuumed. Since this equipment has a special structure of a shell-less cylinder, the specifications are large and the cross-sectional shape is complex, and a rigid shell side tooling of about 40m³ that can withstand a vacuum state is required. In addition to the difficulty in designing and manufacturing the tooling, the vacuuming and helium filling operations of the tooling are time-consuming. At the same time, the consumption of helium is large, and the material waste is serious. Therefore, the suction probe technical method and the tracer probe technical method are not very operable for this equipment. Summary of the invention

[0004] In order to solve the problem that it is difficult to establish vacuum conditions in the shell side and cannot meet the detection requirements, the present application provides a shellless heat exchanger weld sealing detection device and detection method.

[0005] In the first aspect, the present application provides a shellless heat exchanger weld sealing detection device using the following technical solution: A shellless heat exchanger weld sealing detection device, comprising: A negative pressure cylinder, one end of which is attached to the weld between the heat exchange tube and the plate tube, and the other end is fixed to the protective shell, an installation cavity is provided in the protective shell, the interior of the negative pressure cylinder is connected to the installation cavity, and a helium detector body is embedded in the end of the negative pressure cylinder away from the protective shell; A negative pressure mechanism, which is used for pumping air to generate vacuum detection conditions, the negative pressure mechanism is arranged between the negative pressure cylinder and the protective shell, the negative pressure mechanism comprises a partition, a suction disc, a support frame, a block, a linkage rod and a docking rod, the partition is fixed in the negative pressure cylinder, and a disc docking with the heat exchange tube is coaxially fixed on one side of the partition, the suction disc is sealingly slidably connected in the negative pressure cylinder and is located on the other side of the partition, the support frame is fixed in the installation cavity of the protective shell, the block is fixed at one end of the support frame, the linkage rod is slidably connected to the block, and the docking rod is fixed at the axis of the suction disc; A check mechanism is used to prevent airflow from flowing back, and the check mechanism is arranged in the negative pressure cylinder. The check mechanism includes a check tube. There are multiple check tubes, and the multiple check tubes are respectively embedded and fixed on the protective shell and the partition.

[0006] By adopting the above technical solution, the vacuum box method using a negative pressure cylinder to establish vacuum conditions is used to perform helium leak detection tests on the welded joints of the heat exchange tubes and the tube sheets one by one. This can not only quickly meet the vacuum adjustment required for the test, but also quickly complete the test, effectively improving the work efficiency of the test while also improving the accuracy. At the same time, the test method is time-saving, can quickly achieve the vacuum adjustment required to complete the test, and is simple to operate.

[0007] By utilizing the reciprocating motion of the vacuum disk in the negative pressure mechanism and combining it with a check mechanism, the air in the cavity near the weld side in the negative pressure cylinder can be quickly extracted. At the same time, the air away from the weld side can be quickly discharged from the negative pressure cylinder by utilizing the check mechanism, so that the cavity near the weld side in the negative pressure cylinder can quickly reach the vacuum adjustment required to complete the detection. The operation is simple and efficient.

[0008] Optionally, the negative pressure mechanism further includes a first follower rod and a second follower rod, one end of the first follower rod and the second follower rod are rotatably connected to each other, the other end of the first follower rod is fixed to the docking rod, and the other end of the second follower rod is rotatably connected to the linkage rod.

[0009] By adopting the above technical solution, the first driven rod and the second driven rod are combined and linked, so that the linkage rod can drive the vacuum plate to move back and forth in the negative pressure cylinder while sliding back and forth.

[0010] Optionally, the negative pressure mechanism also includes a transmission rod, an adjustment plate and a limit frame, the transmission rod is rotatably connected to the support frame, one end of the adjustment plate is fixed to the transmission rod, and the other end is provided with a lever, the limit frame is fixed on one end of the linkage rod away from the second driven rod, and the lever is slidably engaged in the limit frame.

[0011] By adopting the above technical solution, the rotation of the adjustment plate drives the limit frame to move in linkage, thereby enabling the linkage rod to slide in the clamping block.

[0012] Optionally, the negative pressure mechanism also includes a first pulley, a second pulley and a belt, the first pulley is coaxially fixed to one end of the transmission rod, the second pulley is rotatably connected in the protective shell, the belt is arranged between the first pulley and the second pulley, and two belts are arranged, and two adjacent belts are staggered.

[0013] By adopting the above technical solution, the first pulley and the second pulley can be synchronously linked by using the setting of the belt.

[0014] Optionally, the negative pressure mechanism also includes an active bevel gear, an active bevel gear and a servo motor, the driven bevel gear is coaxially fixed on one side of the second pulley, the active bevel gear is rotatably connected to the top of the inner wall of the active bevel gear and meshes with the driven bevel gear, the servo motor is fixed on the top of the outer wall of the protective shell, and the output shaft of the servo motor is coaxially fixed with the active bevel gear.

[0015] By adopting the above technical solution, the servo motor is used to drive the active bevel gear to rotate, thereby making the active bevel gear mesh and linked.

[0016] Optionally, the check mechanism also includes an isolation chamber, a sliding chamber, a sliding rod, a sealing disk and an abutment joint, the isolation chamber is arranged at one end of the check tube, the sliding chamber is arranged at the other end of the check tube, the diameter of the isolation chamber is smaller than the sliding chamber, and the two are interconnected, the sliding rod is slidably connected in the sliding chamber, the sealing disk is coaxially fixed on the sliding rod, and slides and seals against the inner wall of the sliding chamber, and the abutment joint is coaxially fixed to one end of the sliding rod, and abuts at the connection between the isolation chamber and the sliding chamber.

[0017] By adopting the above technical solution, the sealing disk and the abutment head are used to achieve the barrier sealing effect for the isolation cavity and the sliding cavity.

[0018] Optionally, a cavity is provided inside the sliding rod, and ventilation holes are provided on the sliding rod and the abutment head.

[0019] By adopting the above technical solution, the vent holes are used for ventilation and flow guidance, so that the air can flow in one direction.

[0020] Optionally, an abutment plate is provided at one end of the sliding cavity away from the isolation cavity, and the abutment plate is sleeved on the outside of the sliding rod and slidably connected to the sliding rod. A reset member is also sleeved on the outside of the sliding rod, and one end of the reset member abuts against the abutment plate, and the other end abuts against the sealing plate.

[0021] By adopting the above technical solution, the elastic force of the reset member is utilized to enable the abutment head to be quickly reset, and the isolation cavity and the sliding cavity are isolated and sealed.

[0022] Optionally, a rubber gasket is provided on one end of the negative pressure cylinder away from the protective shell, and an arc chamfer is designed at the edge of the rubber gasket.

[0023] By adopting the above technical solution, the rubber pad is used to improve the sealing between the negative pressure cylinder and the object to be detected.

[0024] In a second aspect, the present application also provides a detection method, comprising the following steps: S1. Equipment positioning: first determine the weld to be inspected, then place the end of the negative pressure cylinder away from the protective shell on the welding point between the heat exchange tube and the tube sheet, and make the weld inside the negative pressure cylinder, while the disc on one side of the partition is in contact with the end of the heat exchange tube; S2, vacuuming, starting the servo motor to drive the active bevel gear to rotate, and at the same time the driven bevel gear meshes and links, and drives the first pulley to rotate through the belt, at this time the transmission rod drives the adjustment plate, and the lever of the adjustment plate slides in the limit frame, and then drives the linkage rod to slide back and forth, and at the same time the first driven rod and the second driven rod are linked, and drive the vacuum plate to reciprocate in the negative pressure cylinder, and combine with the check mechanism to generate negative pressure on the side of the negative pressure cylinder close to the weld until the predetermined pressure is reached; S3. Helium detection: Helium is sprayed on the back of the weld between the heat exchange tube and the tube sheet with a spray gun. If there is a leak in the weld between the heat exchange tube and the tube sheet, under the condition of pressure difference on both sides of the weld, the helium sprayed by the spray gun will flow into the negative pressure cylinder through the gap between the heat exchange tube and the tube sheet and be detected by the helium detector body.

[0025] By adopting the above technical solution, using S1, S2 and S3 to guide the operation, and using the vacuum box method with a negative pressure cylinder to establish vacuum conditions, the helium leak test is performed on the welded joints of the heat exchange tubes and the tube sheets one by one. This can not only quickly meet the vacuum adjustment required for the test, but also quickly complete the test, effectively improving the work efficiency of the test while also improving the accuracy.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. The vacuum box method using a negative pressure cylinder to establish vacuum conditions is used to conduct helium leak tests on the welded joints of the heat exchange tubes and tube sheets one by one. This can not only quickly meet the vacuum adjustment required for the test, but also quickly complete the test, effectively improving the work efficiency and accuracy of the test. At the same time, this test method takes a short time, can quickly achieve the vacuum adjustment required to complete the test, and is simple to operate; 2. The reciprocating motion of the vacuum plate in the negative pressure mechanism is utilized, and combined with the non-return mechanism, the air in the cavity near the weld side in the negative pressure cylinder can be quickly extracted. At the same time, the non-return mechanism is utilized to quickly discharge the air away from the weld side from the negative pressure cylinder, thereby enabling the cavity near the weld side in the negative pressure cylinder to quickly reach the vacuum adjustment required to complete the detection. The operation is simple, efficient and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the detection status of a shellless heat exchanger weld sealing detection device in this embodiment.

[0028] Figure 2 Schematic diagram of the negative pressure cylinder and its overall connection structure in this embodiment.

[0029] Figure 3 Schematic diagram of the negative pressure mechanism structure in this embodiment.

[0030] Figure 4 Schematic diagram of the linkage rod and its overall connection structure in this embodiment.

[0031] Figure 5 Schematic diagram of the cross-sectional structure of the negative pressure cylinder in this embodiment.

[0032] Figure 6 Schematic diagram of the cross-sectional structure of the check pipe in this embodiment.

[0033] Figure 7 Schematic diagram of the sliding rod and its connection structure in this embodiment.

[0034] Description of reference numerals: 1. Negative pressure cylinder; 2. Protective shell; 3. Helium detector body; 4. Negative pressure mechanism; 41. Partition; 42. Vacuum plate; 43. Support frame; 44. Block; 45. Linkage rod; 46. Docking rod; 47. First driven rod; 48. Second driven rod; 49. Transmission rod; 410. Adjustment plate; 411. Limiting frame; 412. First pulley; 413. Second pulley; 414. Belt; 415. Driven bevel gear; 416. Active bevel gear; 417. Servo motor; 5. Check mechanism; 51. Check tube; 52. Isolation chamber; 53. Sliding chamber; 54. Sliding rod; 55. Sealing disk; 56. Abutment joint; 57. Vent hole; 58. Abutment disk; 59. Reset member. DETAILED DESCRIPTION

[0035] The following is combined with Figure 1-7 This application is described in further detail.

[0036] The embodiments of the present application disclose a device and method for detecting the sealing performance of welds of a shellless heat exchanger.

[0037] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] In a first aspect, the present application provides a shellless heat exchanger weld sealing detection device: Reference Figure 1 and Figure 2 A shellless heat exchanger weld tightness detection device comprises a negative pressure cylinder 1, a protective shell 2, a helium detector body 3, a negative pressure mechanism 4 and a non-return mechanism 5. One end of the negative pressure cylinder 1 is attached to the weld between the heat exchange tube and the plate tube, and the other end is fixed on the protective shell 2. An installation cavity is arranged in the protective shell 2. The interior of the negative pressure cylinder 1 is connected with the installation cavity. The end of the negative pressure cylinder 1 away from the protective shell 2 is embedded with the helium detector body 3. The negative pressure mechanism 4 is arranged between the negative pressure cylinder 1 and the protective shell 2. The non-return mechanism 5 is arranged in the negative pressure cylinder 1. The vacuum box method using the negative pressure cylinder 1 to establish a vacuum condition is used to perform a helium leak test on the welded joints of the heat exchange tube and the tube sheet one by one, which can not only quickly meet the requirements of the invention, but also meet the requirements of the invention. The vacuum adjustment required for detection can also be completed quickly, which effectively improves the work efficiency of detection while also improving the accuracy. At the same time, the detection method is time-saving and can quickly achieve the vacuum adjustment required for completing the detection. It is simple to operate and utilizes the reciprocating motion of the vacuum disk 42 in the negative pressure mechanism 4, combined with the check mechanism 5 so that the air in the cavity near the weld side in the negative pressure cylinder 1 can be quickly extracted. At the same time, the check mechanism 5 is utilized so that the air away from the weld side can be quickly discharged from the negative pressure cylinder 1, so that the cavity near the weld side in the negative pressure cylinder 1 can quickly reach the vacuum adjustment required for completing the detection. It is simple to operate and efficient and practical.

[0039] Reference Figure 3 and Figure 4 In the embodiment of the present application, regarding the negative pressure mechanism 4, the negative pressure mechanism 4 includes a partition 41, an exhaust disk 42, a support frame 43, a block 44, a linkage rod 45, a docking rod 46, a first driven rod 47 and a second driven rod 48. The first driven rod 47 and the second driven rod 48 are linked together, so that the linkage rod 45 can drive the exhaust disk 42 to reciprocate in the negative pressure cylinder 1 while sliding back and forth, thereby quickly evacuating the negative pressure cylinder 1.

[0040] Specifically, the partition 41 is fixed in the negative pressure cylinder 1, and a disc docked with the heat exchange tube is coaxially fixed on one side of the partition 41, the vacuum disk 42 is sealingly and slidably connected in the negative pressure cylinder 1, and is located on the other side of the partition 41, the support frame 43 is fixed in the installation cavity of the protective shell 2, the block 44 is fixed at one end of the support frame 43, the linkage rod 45 is slidably connected to the block 44, the docking rod 46 is fixed at the axis of the vacuum disk 42, one end of the first driven rod 47 and the second driven rod 48 are rotatably connected to each other, the other end of the first driven rod 47 is fixed on the docking rod 46, and the other end of the second driven rod 48 is rotatably connected to the linkage rod 45.

[0041] Reference Figure 5 and Figure 6 In the embodiment of the present application, regarding the non-return mechanism 5, the non-return mechanism 5 includes a non-return tube 51, an isolation chamber 52, a sliding chamber 53, a sliding rod 54, a sealing disk 55, abutment 56 and a vent 57. The vent 57 is used for ventilation and diversion to allow air to flow in one direction, and the sealing disk 55 and the abutment 56 are used to achieve a blocking and sealing effect on the isolation chamber 52 and the sliding chamber 53.

[0042] Specifically, a plurality of check tubes 51 are provided, and the plurality of check tubes 51 are respectively embedded and fixed on the protective shell 2 and the partition 41, the isolation chamber 52 is provided at one end of the check tube 51, the sliding chamber 53 is provided at the other end of the check tube 51, and the diameter of the isolation chamber 52 is smaller than the sliding chamber 53, and the two are interconnected, the sliding rod 54 is slidably connected in the sliding chamber 53, the sealing disk 55 is coaxially fixed on the sliding rod 54, and slides and seals against the inner wall of the sliding chamber 53, and the abutment joint 56 is coaxially fixed on one end of the sliding rod 54, and abuts against the connection between the isolation chamber 52 and the sliding chamber 53.

[0043] The negative pressure mechanism 4 further includes a transmission rod 49 , an adjustment plate 410 and a limit frame 411 . The rotation of the adjustment plate 410 drives the limit frame 411 to move in conjunction, thereby enabling the linkage rod 45 to slide in the block 44 .

[0044] Specifically, the transmission rod 49 is rotatably connected to the support frame 43, one end of the adjustment plate 410 is fixed on the transmission rod 49, and the other end is provided with a lever, the limit frame 411 is fixed on the end of the linkage rod 45 away from the second driven rod 48, and the lever is slidably engaged in the limit frame 411.

[0045] In the embodiment of the present application, the negative pressure mechanism 4 also includes a first pulley 412, a second pulley 413, a belt 414, an active bevel gear 416, an active bevel gear 416 and a servo motor 417. The servo motor 417 is used to drive the active bevel gear 416 to rotate, thereby making the active bevel gear 416 mesh and link, and the setting of the belt 414 enables the first pulley 412 and the second pulley 413 to be synchronously linked.

[0046] The first pulley 412 is coaxially fixed to one end of the transmission rod 49, the second pulley 413 is rotatably connected in the protective shell 2, the belt 414 is arranged between the first pulley 412 and the second pulley 413, and two belts 414 are arranged, and the two adjacent belts 414 are staggered. The driven bevel gear 415 is coaxially fixed to one side of the second pulley 413, the driving bevel gear 416 is rotatably connected to the top of the inner wall of the driving bevel gear 416 and meshes with the driven bevel gear 415, and the servo motor 417 is fixed to the top of the outer wall of the protective shell 2, and the output shaft of the servo motor 417 is coaxially fixed to the driving bevel gear 416.

[0047] A cavity is provided inside the slide bar 54 , and ventilation holes 57 are provided on the slide bar 54 and the abutment joint 56 . The ventilation holes 57 are used for ventilation and flow guidance to allow air to flow in one direction.

[0048] Reference Figure 7 Specifically, in the embodiment of the present application, an abutment disk 58 is provided at one end of the sliding cavity 53 away from the isolation cavity 52. ​​The abutment disk 58 is sleeved on the outside of the sliding rod 54 and is slidably connected to the sliding rod 54. A reset member 59 is also sleeved on the outside of the sliding rod 54. One end of the reset member 59 abuts against the abutment disk 58, and the other end abuts against the sealing disk 55. The elastic force of the reset member 59 is utilized to enable the abutment joint 56 to be quickly reset, and the isolation cavity 52 and the sliding cavity 53 are isolated and sealed.

[0049] In the embodiment of the present application, a rubber gasket is provided on the end of the negative pressure cylinder 1 away from the protective shell 2, and the edge of the rubber gasket is designed with an arc chamfer, so as to improve the sealing between the negative pressure cylinder 1 and the object to be detected.

[0050] It should be noted that in the embodiment of the present application, the reset member 59 is a cylindrical spring. In other embodiments, other forms of reset members are also possible, which are also preferred embodiments of the present application.

[0051] The implementation principle of the shellless heat exchanger weld sealing detection device and detection method of the embodiment of the present application is as follows: first determine the weld to be detected, then set the end of the negative pressure cylinder 1 away from the protective shell 2 on the welding place between the heat exchange tube and the tube sheet, and make the weld located in the negative pressure cylinder 1, and at the same time, the disk on one side of the partition 41 abuts against the end of the heat exchange tube, and then start the servo motor 417 to drive the active bevel gear 416 to rotate, and at the same time, the driven bevel gear 415 is meshed and linked, and the first pulley 412 is driven to rotate through the belt 414, at this time, the transmission rod 49 drives the adjustment plate 410, and the lever of the adjustment plate 410 is in the limit frame 411 The first driven rod 47 and the second driven rod 48 are linked to each other, and drive the vacuum plate 42 to reciprocate in the negative pressure cylinder 1. During the reciprocating motion, the sliding rod 54 slides back and forth in the sliding cavity 53, so that the air circulates in one direction, so that a negative pressure is generated on the side close to the weld in the negative pressure cylinder 1 until a predetermined pressure is reached. Then, helium is sprayed on the back side of the weld between the heat exchange tube and the tube sheet with a spray gun. If there is a leak in the weld between the heat exchange tube and the tube sheet, under the condition of a pressure difference on both sides of the weld, the helium sprayed by the spray gun will flow into the negative pressure cylinder 1 through the gap between the heat exchange tube and the tube sheet, and be detected by the helium detector body 3.

[0052] Second, refer to Figure 1-Figure 7 , the present application also provides a detection method, comprising the following steps: S1. Equipment positioning: first determine the weld to be inspected, then sleeve the end of the negative pressure cylinder 1 away from the protective shell 2 on the welding point between the heat exchange tube and the tube sheet, and make the weld inside the negative pressure cylinder 1, while the disc on one side of the partition 41 abuts against the end of the heat exchange tube; S2, vacuuming, starting the servo motor 417 to drive the active bevel gear 416 to rotate, and at the same time the driven bevel gear 415 is meshed and linked, and the first pulley 412 is driven to rotate through the belt 414, at this time the transmission rod 49 drives the adjustment plate 410, and the lever of the adjustment plate 410 slides in the limit frame 411, and then drives the linkage rod 45 to slide back and forth, and at the same time the first driven rod 47 and the second driven rod 48 are linked, and drive the vacuum plate 42 to reciprocate in the negative pressure cylinder 1, and in combination with the non-return mechanism 5, a negative pressure is generated on the side of the negative pressure cylinder 1 close to the weld until a predetermined pressure is reached; S3, helium detection, use a spray gun to spray helium on the back side of the weld between the heat exchange tube and the tube sheet. If there is a leak in the weld between the heat exchange tube and the tube sheet, under the condition of pressure difference on both sides of the weld, the helium sprayed by the spray gun will flow into the negative pressure cylinder 1 through the gap between the heat exchange tube and the tube sheet, and be detected by the helium detector body 3.

[0053] The present application guides the operation through S1, S2 and S3, and performs helium leak detection tests on the welded joints of the heat exchange tubes and the tube sheets one by one by using the vacuum box method of establishing vacuum conditions through the negative pressure cylinder 1. This can not only quickly meet the vacuum adjustment required for the detection, but also quickly complete the detection, effectively improving the work efficiency of the detection while also improving the accuracy.

[0054] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A shellless heat exchanger weld sealing detection device, characterized in that: include: A negative pressure cylinder (1), one end of the negative pressure cylinder (1) being attached to the weld between the heat exchange tube and the plate tube, and the other end being fixed to the protective shell (2); an installation cavity being provided in the protective shell (2); the interior of the negative pressure cylinder (1) being connected to the installation cavity; and a helium detector body (3) being embedded at one end of the negative pressure cylinder (1) away from the protective shell (2); A negative pressure mechanism (4) for extracting air to generate a vacuum detection condition, the negative pressure mechanism (4) being arranged between the negative pressure cylinder (1) and the protective shell (2), the negative pressure mechanism (4) comprising a partition (41), an air extraction disk (42), a support frame (43), a block (44), a linkage rod (45) and a docking rod (46), the partition (41) being fixed in the negative pressure cylinder (1), and a disk docking with the heat exchange tube being coaxially fixed on one side of the partition (41), the air extraction disk (42) being sealingly slidably connected in the negative pressure cylinder (1) and being located on the other side of the partition (41), the support frame (43) being fixed in the mounting cavity of the protective shell (2), the block (44) being fixed at one end of the support frame (43), the linkage rod (45) being slidably connected to the block (44), and the docking rod (46) being fixed at the axis of the air extraction disk (42); A non-return mechanism (5) is used to prevent airflow from flowing back, and the non-return mechanism (5) is arranged in the negative pressure cylinder (1), and the non-return mechanism (5) comprises a non-return tube (51), and a plurality of the non-return tubes (51) are provided, and the plurality of the non-return tubes (51) are respectively embedded and fixed on the protective shell (2) and the partition plate (41).

2. A shellless heat exchanger weld sealing detection device according to claim 1, characterized in that: The negative pressure mechanism (4) further comprises a first driven rod (47) and a second driven rod (48), one end of the first driven rod (47) and the second driven rod (48) being rotatably connected to each other, the other end of the first driven rod (47) being fixed to the docking rod (46), and the other end of the second driven rod (48) being rotatably connected to the linkage rod (45).

3. A shellless heat exchanger weld sealing detection device according to claim 2, characterized in that: The negative pressure mechanism (4) further comprises a transmission rod (49), an adjustment plate (410) and a limit frame (411); the transmission rod (49) is rotatably connected to the support frame (43); one end of the adjustment plate (410) is fixed to the transmission rod (49) and the other end is provided with a shifting rod; the limit frame (411) is fixed to one end of the linkage rod (45) away from the second driven rod (48), and the shifting rod is slidably engaged in the limit frame (411).

4. The shellless heat exchanger weld sealing detection device according to claim 3, characterized in that: The negative pressure mechanism (4) further comprises a first pulley (412), a second pulley (413) and a belt (414); the first pulley (412) is coaxially fixed to one end of the transmission rod (49); the second pulley (413) is rotatably connected in the protective shell (2); the belt (414) is arranged between the first pulley (412) and the second pulley (413); two belts (414) are arranged, and two adjacent belts (414) are arranged in a staggered manner.

5. A shellless heat exchanger weld sealing detection device according to claim 4, characterized in that: The negative pressure mechanism (4) further comprises a driven bevel gear (415), a driving bevel gear (416) and a servo motor (417); the driven bevel gear (415) is coaxially fixed to one side of the second pulley (413); the driving bevel gear (416) is rotatably connected to the top of the inner wall of the driving bevel gear (416) and meshes with the driven bevel gear (415); the servo motor (417) is fixed to the top of the outer wall of the protective shell (2), and the output shaft of the servo motor (417) is coaxially fixed to the driving bevel gear (416).

6. The shellless heat exchanger weld sealing detection device according to claim 1, characterized in that: The non-return mechanism (5) further comprises an isolation chamber (52), a sliding chamber (53), a sliding rod (54), a sealing disk (55) and an abutment joint (56); the isolation chamber (52) is arranged at one end of the non-return tube (51), the sliding chamber (53) is arranged at the other end of the non-return tube (51), the diameter of the isolation chamber (52) is smaller than that of the sliding chamber (53), and the two are interconnected; the sliding rod (54) is slidably connected in the sliding chamber (53), the sealing disk (55) is coaxially fixed on the sliding rod (54), and slides and seals against the inner wall of the sliding chamber (53); the abutment joint (56) is coaxially fixed on one end of the sliding rod (54), and abuts against the connection between the isolation chamber (52) and the sliding chamber (53).

7. A shellless heat exchanger weld sealing detection device according to claim 6, characterized in that: A cavity is provided through the interior of the sliding rod (54), and a vent hole (57) is provided through the sliding rod (54) and the abutment head (56).

8. The device for detecting the sealing performance of weld joints of a shellless heat exchanger according to claim 6, characterized in that: An abutment disk (58) is provided at one end of the sliding cavity (53) away from the isolation cavity (52). The abutment disk (58) is sleeved on the outside of the sliding rod (54) and is slidably connected to the sliding rod (54). A reset member (59) is also sleeved on the outside of the sliding rod (54). One end of the reset member (59) abuts against the abutment disk (58) and the other end abuts against the sealing disk (55).

9. The shellless heat exchanger weld sealing detection device according to claim 1, characterized in that: A rubber gasket is provided on one end of the negative pressure cylinder (1) away from the protective shell (2), and the edge of the rubber gasket is designed with an arc chamfer.

10. A detection method, applied to a shellless heat exchanger weld sealing detection device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Positioning the equipment, first determine the weld to be inspected, then sleeve the end of the negative pressure cylinder (1) away from the protective shell (2) over the weld between the heat exchange tube and the tube sheet, and make the weld inside the negative pressure cylinder (1), while the disc on one side of the partition (41) abuts against the end of the heat exchange tube; S2, vacuuming, starting the servo motor (417) to drive the active bevel gear (416) to rotate, while the driven bevel gear (415) meshes and links, and drives the first pulley (412) to rotate through the belt (414), at this time, the transmission rod (49) drives the adjustment plate (410), and the lever of the adjustment plate (410) slides in the limit frame (411), thereby driving the linkage rod (45) to slide back and forth, and at the same time the first driven rod (47) and the second driven rod (48) are linked, and drive the vacuum plate (42) to reciprocate in the negative pressure cylinder (1), and in combination with the non-return mechanism (5), a negative pressure is generated on the side of the negative pressure cylinder (1) close to the weld until a predetermined pressure is reached; S3. Helium detection: Helium is sprayed on the back side of the weld between the heat exchange tube and the tube sheet using a spray gun. If there is a leak in the weld between the heat exchange tube and the tube sheet, under the condition of pressure difference on both sides of the weld, the helium sprayed by the spray gun will flow into the negative pressure cylinder (1) through the gap between the heat exchange tube and the tube sheet and be detected by the helium detector body (3).

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