Device and method for improving hydraulic expansion quality of a finned heat exchanger

Abstract

The present application belongs to the technical field of heat exchanger pipe processing, and specifically discloses a device and method for improving the hydraulic expansion quality of a tube-fin heat exchanger, which is used for the expansion of U-shaped heat exchange copper pipes. The device comprises a first clamping mechanism, a second clamping mechanism and a hydraulic mechanism on the device table. The first clamping mechanism clamps the bent pipe section of the heat exchange copper pipe. The second clamping mechanism clamps the straight pipe section of the heat exchange copper pipe. The hydraulic mechanism comprises at least one set of hydraulic expansion terminals, each of which comprises two expansion joints connected to the open ends of the two straight pipe sections of the heat exchange copper pipe. The expansion joints are detachably connected to an internal mandrel that can be inserted into the straight pipe section of the heat exchange copper pipe. The two expansion joints are connected to the same hydraulic power device. The device and method can improve the expansion efficiency, avoid damage to the internal threads of the copper pipe, effectively prevent the bending and deformation of the heat exchange copper pipe, and improve the hydraulic expansion quality of the copper pipe and the fin and the heat exchange efficiency.

Description

Technical Field

[0001] This invention belongs to the field of heat exchanger tube processing technology, specifically relating to a device and method for improving the quality of hydraulic expansion joints in tube-fin heat exchangers. Background Technology

[0002] Studies have shown that small-diameter heat exchanger copper tubes can increase the heat transfer area. The reduction in diameter technology can increase the number of heat exchanger tubes and decrease the distance between them, thereby increasing the heat transfer area, improving heat transfer efficiency, and achieving a higher heat exchange effect. Furthermore, the use of small-diameter heat exchanger copper tubes also allows for the design of smaller heat exchangers, thus reducing costs and the space required for installation. Therefore, companies are not limiting their research on small-diameter heat exchanger copper tubes to the traditional sizes currently on the market, but are investing in research on even smaller diameter tubes.

[0003] Due to significant limitations in the processing of small-diameter heat exchanger copper tubes, current research experiments on hydraulic expansion joint technology for heat exchanger copper tubes show that traditional processing methods involve radial forces during the hydraulic expansion joint of slender copper tubes and fins, causing irregular deformation of the small-diameter copper tubes. Furthermore, because the bent sections of the tubes in the manufacturing process of tube-fin heat exchanger copper tubes are formed by bending straight copper tubes, the mechanical properties of the bent sections change, requiring greater expansion pressure than other parts of the heat exchanger copper tube. Under conditions that meet the straight tube size requirements, the dimensions of the bent sections of the heat exchanger copper tubes often do not change significantly. During heat exchanger operation, this situation reduces the refrigerant flow rate to some extent, leading to a decrease in the heat exchanger's heat exchange performance.

[0004] In summary, existing tube-fin heat exchanger expansion joint devices and methods are prone to defects such as uneven radial dimensions of heat exchange copper tubes, damage to internal thread structures, and bending deformation when manufacturing small-diameter tube-fin heat exchangers.

[0005] Therefore, it is necessary to propose a hydraulic expansion joint device and expansion joint method for tube-fin heat exchangers to solve the above-mentioned technical problems. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems to a certain extent. To this end, the present invention proposes an apparatus and method for improving the quality of hydraulic expansion joints of tube-fin heat exchangers. By using this apparatus and method to hydraulically expand the heat exchange copper tubes of tube-fin heat exchangers, the pressure can be evenly applied to the inner surface of the heat exchange copper tubes, thereby solving problems such as axial shrinkage of heat exchange copper tubes, damage to internal threads, and excessive deformation of fins in the prior art.

[0007] To achieve the above objectives, in one aspect, the present invention provides an apparatus for improving the quality of hydraulic expansion joints in a tube-fin heat exchanger, used for expanding U-shaped heat exchange copper tubes, comprising a first clamping mechanism, a second clamping mechanism, and a hydraulic mechanism located on a platform; the first clamping mechanism clamps the bent section of the heat exchange copper tube; the second clamping mechanism clamps the straight section of the heat exchange copper tube; the hydraulic mechanism includes at least one set of hydraulic expansion joints, each hydraulic expansion joint including two expansion joints connected to the open ends of the two straight sections of the heat exchange copper tube, each expansion joint being detachably connected to an internal mandrel capable of being inserted into the straight section of the heat exchange copper tube, and both expansion joints being connected to the same hydraulic power unit.

[0008] Preferably, the built-in mandrel is made of stainless steel hollow tube.

[0009] Preferably, the length of the built-in mandrel is consistent with the length of the straight section of the U-shaped heat exchange copper tube.

[0010] Preferably, the tube body of the built-in mandrel has several through holes evenly distributed.

[0011] Preferably, both the first clamping mechanism and the second clamping mechanism can be detachably connected to the device platform.

[0012] Preferably, the hydraulic expansion terminal includes two expansion joints, which are spaced apart, with the spacing being consistent with the distance between the two ports of the heat exchange copper tube, and the two expansion joints are connected to the same hydraulic power unit.

[0013] Preferably, the expansion joint has a threaded hole in the center, and a through-hole bolt is threaded into the threaded hole. The through-hole bolt has a hole at its axial center to accommodate the heat exchange copper tube. One end of the built-in mandrel is provided with a base. The end of the built-in mandrel with the base is inserted into the threaded hole, and a sealing washer is fitted onto the built-in mandrel. After the heat exchange copper tube passes through the hole of the through-hole bolt, the through-hole bolt is screwed into the threaded hole. The sealing washer is compressed and deformed, pressing against the base of the built-in mandrel.

[0014] Preferably, the hydraulic mechanism is slidably connected to the device platform in a direction perpendicular to the heat exchange copper tube.

[0015] Preferably, the hydraulic mechanism further includes a hydraulic distributor that reciprocates along the length of the heat exchange copper tube, and the side of the hydraulic distributor facing the heat exchanger platform is provided with at least one set of hydraulic expansion terminals.

[0016] On the other hand, the present invention provides a method for improving the hydraulic expansion quality of a tube-fin heat exchanger, using the apparatus described in any of the above claims for improving the hydraulic expansion quality of a tube-fin heat exchanger, the method comprising the following steps:

[0017] Step 1: Fix the heat exchanger onto the hydraulic expansion joint device of the riser fin heat exchanger;

[0018] Step 2: Insert the built-in mandrel into the heat exchange copper tube from the open end of the heat exchange copper tube, and seal the heat exchange copper tube to the hydraulic expansion terminal;

[0019] Step 3: Start the hydraulic mechanism, inject hydraulic oil into the heat exchange copper tube through the built-in mandrel and pressurize it, so that the hydraulic oil acts evenly on the inner surface of the heat exchange copper tube. Under the pressure of the hydraulic oil, the heat exchange copper tube undergoes plastic deformation and expands evenly.

[0020] Step 4: Repeat steps 2 and 3 to complete the expansion connection of the other heat exchange copper tubes in the heat exchanger.

[0021] The present invention discloses the following beneficial effects:

[0022] Compared with traditional mechanical or mechanical shrinkage expansion forming technology, in the expansion device and expansion method of this invention, hydraulic oil flows in along the gap between the inner wall of the copper tube and the mandrel, and the inner wall of the tube is in full contact with the hydraulic oil. At the same time, the liquid flow space is also increased, and the liquid pressure value inside the tube decreases slightly or tends to stabilize. This can avoid irregular changes in the diameter of the slender heat exchange copper tube under the action of liquid pressure, and ensure that the hydraulic oil is evenly distributed to the bend section of the heat exchange copper tube, forming a good expansion effect on the bend section. This improves the stress concentration at the bend caused by the heat exchange copper tube during the bend forming process, so that the displacement of the tube wall after expansion is consistent with the expansion effect of the straight section, thereby improving the expansion quality and heat exchange efficiency of the entire heat exchange copper tube. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0024] Figure 1 This is a front view of the device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to the present invention.

[0025] Figure 2 The right view of the device for improving the hydraulic expansion joint quality of tube-fin heat exchangers according to the present invention;

[0026] Figure 3 This is a top perspective view of the device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to the present invention.

[0027] Figure 4This is a three-dimensional structural diagram of the device for improving the hydraulic expansion joint quality of tube-fin heat exchangers according to the present invention;

[0028] Figure 5 The effect of placing a heat exchanger on the device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to the present invention. Figure 1 ;

[0029] Figure 6 The effect of placing a heat exchanger on the device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to the present invention. Figure 2 ;

[0030] Figure 7 This is a schematic diagram showing the placement of the heat exchanger in the device for improving the hydraulic expansion joint quality of the tube-fin heat exchanger according to the present invention.

[0031] Figure 8 This is a schematic diagram of the hydraulic mechanism in the device for improving the hydraulic expansion joint quality of tube-fin heat exchangers according to the present invention. Figure 1 ;

[0032] Figure 9 This is a schematic diagram of the hydraulic mechanism in the device for improving the hydraulic expansion joint quality of tube-fin heat exchangers according to the present invention. Figure 2 ;

[0033] Figure 10 This is a schematic diagram of the structure of the first clamp in the device for improving the hydraulic expansion joint quality of tube-fin heat exchangers according to the present invention;

[0034] Figure 11 This is a schematic diagram of the structure of the second clamp in the device for improving the hydraulic expansion joint quality of tube-fin heat exchangers according to the present invention;

[0035] Figure 12 This is a schematic diagram showing the connection between the hydraulic expansion terminal and the heat exchanger in an embodiment of the present invention;

[0036] Figure 13 This is a diagram showing the internal structure of the heat exchange copper tube in an embodiment of the present invention;

[0037] Figure 14 This is a diagram showing the positional relationship between the heat exchange copper tube and the built-in mandrel in an embodiment of the present invention;

[0038] Figure 15 This is a schematic diagram of the hydraulic oil flow direction in an embodiment of the present invention;

[0039] Figure 16 This is a schematic diagram of the hydraulic oil flow direction when the present invention uses an internal mandrel with a hole in the pipe wall for expansion jointing.

[0040] Figure 17 This invention provides a comparison of the performance of heat exchangers expanded using the apparatus and method of this invention with those expanded using existing technologies. Figure 1 ;

[0041] Figure 18 This invention provides a comparison of the performance of heat exchangers expanded using the apparatus and method of this invention with those expanded using existing technologies. Figure 2 .

[0042] The components include: 1. Device platform; 2. Heat exchanger placement platform; 3. Second positioning platform; 4. First positioning platform; 5. First clamp; 6. Second clamp; 7. Hydraulic mechanism; 8. Built-in mandrel; 9. Heat exchanger to be processed; 10. Hydraulic expansion terminal; 51. First support; 52. Second support; 53. First cylinder; 54. First upper clamp; 55. U-shaped groove upper pressure block; 56. U-shaped limiting groove; 61. Third support; 62. Fourth support; 63. Second cylinder. 64. Second upper clamp; 65. Upper pressure block of straight pipe groove; 66. Lower pressure block of straight pipe groove; 71. Slide rail; 72. First slide block; 73. Lead screw; 74. First rotary motor; 75. Second slide block; 76. Slide rod; 77. Second rotary motor; 78. Hydraulic distributor; 79. Connecting terminal; 81. Liquid inlet; 82. Through hole; 91. Heat exchange copper tube; 92. Bend section; 101. Expansion joint; 102. Through hole bolt; 103. Sealing gasket. Detailed Implementation

[0043] 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.

[0044] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] Reference Figures 1 to 12As shown, the present invention provides a device for improving the hydraulic expansion quality of a tube-fin heat exchanger, including a heat exchanger placement platform 2 set on the device platform 1, a second positioning platform 3 located in front of the heat exchanger placement platform 2, a first positioning platform 4 located behind the heat exchanger placement platform 2, a first clamp 5 set above the first positioning platform 4, a second clamp 6 set above the second positioning platform 3, and a hydraulic mechanism 7 movable on the device platform 1. The device platform 1 is a horizontal platform, and its bottom can support an electrical control cabinet or device bracket (not shown in the figure for ease of understanding). The heat exchanger placement platform 2 is fixedly connected to the device platform 1 and has an upper surface that is higher than the device platform 1 for placing the heat exchanger. The hydraulic mechanism 7 is located on one side of the heat exchanger placement platform 2, which is defined as the front side of the heat exchanger placement platform 2. On the rear side of the heat exchanger placement platform 2, that is, the side away from the hydraulic mechanism 7, a first positioning platform 4 is fixedly connected to the device platform 1. A first clamp 5 is located above the first positioning platform 4. The first positioning platform 4 and the first clamp 5 together form a first clamping mechanism, which is used to clamp and position the bent pipe section 92 of the heat exchanger. On the front side of the heat exchanger placement platform 2, that is, on the device platform 1 between the heat exchanger placement platform 2 and the hydraulic mechanism 7, a... A second positioning platform 3 is connected, and a second clamp 6 is located above the second positioning platform 3. The second positioning platform 3 and the second clamp 6 together form a second clamping mechanism, which is used to clamp and position the straight pipe section of the heat exchanger. After the heat exchanger is placed and positioned, its straight pipe section faces the hydraulic mechanism 7 for easy connection. The hydraulic mechanism 7 includes a hydraulic distributor 78. The side of the hydraulic distributor 78 facing the heat exchanger is connected to a hydraulic expansion terminal 10 for connecting with the heat exchange copper tube 91 in the heat exchanger. The hydraulic expansion terminal 10 is detachably connected to an internal mandrel 8 that can be inserted into the heat exchange copper tube 91. The internal mandrel 8 is a hollow tube and is connected to a hydraulic power device through the hydraulic distributor 78 to press hydraulic oil into the heat exchange copper tube 91, thereby hydraulically expanding the heat exchange copper tube 91.

[0046] In the above embodiments, such as Figure 4 , Figure 8 and Figure 9As shown, the hydraulic mechanism 7 includes two slide rails 71 mounted on the device platform 1. The two slide rails 71 are arranged along the left and right direction of the device platform 1 (perpendicular to the length direction of the heat exchange copper tube 91 in the heat exchanger). A first slide block 72 slides on the two slide rails 71. The first slide block 72 is reciprocated by a lead screw 73. One end of the lead screw 73 is threaded to the first slide block 72, and the other end is connected to the output shaft of the first rotary motor 74. A second slide block 75 and a second rotary motor 77 are fixedly mounted above the first slide block 72. A slide groove is opened on the second slide block 75, and a slide rod 76 is slidably connected in the slide groove. The slide rod 76 slides on the second slide block 75 in a direction perpendicular to the slide rails 71. The upper surface of the slide rod 76 is a rack structure, which meshes with the second rotary motor 77 and reciprocates towards or away from the heat exchanger placement platform 2 as the second rotary motor 77 moves. A hydraulic distributor 78 is fixedly connected to one end of the slide rod 76 near the heat exchanger placement platform 2. The side of the hydraulic distributor 78 facing the heat exchanger placement platform 2 has at least one set of hydraulic expansion terminals 10 for connecting the built-in mandrel 8. In this embodiment, three sets of hydraulic expansion terminals 10 are specifically provided, allowing simultaneous expansion operations on three heat exchange copper tubes 91. Each set of hydraulic expansion terminals 10 includes two expansion joints 101 for connecting the two ports of the U-shaped heat exchange copper tube 91. On the other side of the hydraulic distributor 78 (the side away from the heat exchanger placement platform 2), there are connection terminals 79 of the same number as the hydraulic expansion terminals 10, connected one-to-one. The connection terminals 79 are used to connect to a hydraulic power unit via pipelines.

[0047] Further optimize the plan, such as Figure 12 As shown, the hydraulic expansion terminal 10 includes two expansion joints 101. Each expansion joint 101 has a through-hole bolt 102 internally threaded. The two expansion joints 101 are spaced apart, with the spacing matching the distance between the two ends of the U-shaped heat exchange copper tube 91. A threaded hole is located in the center of each expansion joint 101. The through-hole bolt 102 has an axially centered hole to accommodate the heat exchange copper tube 91. An internal mandrel 8, connected to the expansion joint 101, has a base at its end. During connection, the end of the internal mandrel 8 with the base is inserted into the threaded hole, and a sealing washer 103 is fitted onto the internal mandrel 8. The heat exchange copper tube 91 is inserted into the hole of the through-hole bolt 102, and the through-hole bolt 102 is screwed into the threaded hole. The heat exchange copper tube 91 deforms by compressing the sealing washer 103, and presses against the base of the internal mandrel 8, achieving a sealed connection.

[0048] In the above embodiments, such as Figure 4 and Figure 10As shown, the first clamp 5 includes a first support 51 and a second support 52 fixedly connected to the device platform 1 on both sides of the first positioning platform 4. A downward-facing first cylinder 53 is fixedly connected to the first support 51 and the second support 52. The output shafts of the two first cylinders 53 are fixedly connected to a first upper clamp 54. A plurality of U-shaped groove upper pressure blocks 55 that cooperate with the first positioning platform 4 are detachably installed on the lower surface of the first upper clamp 54. The lower surface of the U-shaped groove upper pressure block and the upper surface of the first positioning platform 4 are U-shaped limiting grooves 56 with semi-circular cross sections that cooperate with each other. The upper and lower U-shaped limiting grooves 56 are pressed together to form a limiting groove 1, which accommodates the bent section 92 of the heat exchange copper tube 91 to enter.

[0049] In the above embodiments, such as Figure 11 As shown, the second clamp 6 includes a third support 61 and a fourth support 62 fixedly connected to the device platform 1 on both sides of the second positioning platform 3. A downward-facing second cylinder 63 is fixedly connected to the third support 61 and the fourth support 62. The output shafts of the two second cylinders 63 are fixedly connected to a second upper clamp 64. A plurality of straight pipe groove upper pressure blocks 65 that cooperate with the second positioning platform 3 are installed on the lower surface of the second upper clamp 64. The lower surface of the straight pipe groove upper pressure block 65 and the upper surface of the second positioning platform 3 have mutually cooperating straight grooves with a semi-circular cross section. The upper and lower straight grooves are pressed to form a limiting groove II, which accommodates the straight pipe section of the heat exchange copper tube 91 to enter.

[0050] It should be understood that the first clamp 5 and the second clamp 6 in this embodiment are only one type of structure that can limit the heat exchange copper tube 91. Other structures that can clamp and limit the heat exchange copper tube 91 can be used as alternatives to this embodiment, and are not further limited here.

[0051] In a further optimized design, the first positioning platform 4 and the second positioning platform 3 are detachably connected to the device platform 1, and the first clamp 5 and the second clamp 6 are detachably connected to the device platform 1. The positions of the first positioning platform 4, the first clamp 5, the second positioning platform 3, and the second clamp 6 are adjusted according to the different sizes of the heat exchangers to meet the clamping and positioning requirements of heat exchangers of different lengths.

[0052] In some embodiments, the first positioning stage 4 and the first clamp 5 are designed as an integral unit and are slidably connected to the device table 1, which can quickly adjust their position according to the size changes of the heat exchanger to meet the processing requirements of heat exchangers of different sizes.

[0053] In the above embodiments, the mating relationship between the built-in mandrel 8 and the heat exchange copper tube 91 is as follows: Figure 14 As shown, the built-in mandrel 8 is inserted into the heat exchange copper tube 91, and a hydraulic expansion terminal 10 is connected to the end of the built-in mandrel 8 located outside the heat exchange copper tube 91.

[0054] In the above embodiments, the internal thread structure of the heat exchange copper tube 91 is as follows: Figure 13 As shown, for a small-diameter internally threaded heat exchange copper tube 91, an internal mandrel 8 is placed inside the heat exchange copper tube 91. Hydraulic oil is filled into the internal mandrel 8 and first flows to the bend section 92 of the heat exchange copper tube 91 before flowing back to the space between the thread teeth and the internal mandrel 8.

[0055] In a further optimized design, the built-in mandrel 8 is made of 304 stainless steel hollow tube.

[0056] In a further optimized design, the length of the built-in mandrel 8 is consistent with the length of the straight section of the U-shaped heat exchange copper tube 91.

[0057] In a further optimized design, the inner mandrel 8 has several through holes 82 evenly distributed on its tube body, such as... Figure 16 As shown, the liquid pressure acts on the inner wall of the heat exchange copper tube 91 through the through hole 82 on the surface of the built-in mandrel 8. The hydraulic oil flows in along the gap between the inner wall of the heat exchange copper tube 91 and the built-in mandrel 8, and the inner wall of the heat exchange copper tube 91 is in full contact with the hydraulic oil. At the same time, the liquid flow space also increases, and the liquid pressure value inside the heat exchange copper tube 91 decreases slightly or tends to stabilize. The test shows that this segmented pressure fluctuation further improves the expansion quality of the tube. Moreover, through the guiding effect of the stainless steel straight tube, the hydraulic oil is evenly distributed to the bend section 92 of the heat exchange copper tube 91, which forms a good expansion effect on the bend section 92. This can improve the stress concentration at the bend caused by the bending of the heat exchange copper tube 91 during the bending process, so that the displacement after the tube diameter is expanded can achieve the same expansion effect as the straight section, resulting in better tube diameter consistency and thus improving the overall expansion quality of the heat exchange copper tube 91.

[0058] The present invention also provides a method for improving the quality of hydraulic expansion joints in a tube-fin heat exchanger, used for the expansion joint of heat exchange copper tubes 91 in a tube-fin heat exchanger, employing the apparatus described in any one of the above-mentioned methods for improving the quality of hydraulic expansion joints in a tube-fin heat exchanger, the method comprising the following steps:

[0059] Step 1: Place the heat exchanger on the heat exchanger placement platform 2, and run the first clamp 5 and the second clamping structure to complete the positioning of the heat exchanger.

[0060] Step 2: Insert the built-in mandrel 8 into the heat exchange copper tube 91 port of the heat exchanger, and seal the heat exchange copper tube 91 port to the hydraulic expansion terminal 10;

[0061] Step 3: Start the hydraulic mechanism 7. The hydraulic oil enters the heat exchange copper tube 91 through the built-in mandrel 8 and fills the gap between the heat exchange copper tube 91 and the built-in mandrel 8. This allows the hydraulic oil to act evenly on the inner surface of the heat exchange copper tube 91 and pressurize it. Under the pressure of the hydraulic oil, the heat exchange copper tube 91 undergoes plastic deformation and expands evenly.

[0062] Step 4: Repeat steps 2 and 3 to complete the expansion connection of the other heat exchange copper tubes 91 in the heat exchanger.

[0063] This invention analyzes the principle of stress and deformation during the expansion of heat exchanger copper tubes and designs and develops a novel device to improve the hydraulic expansion quality of small-diameter tube-fin heat exchangers, replacing the traditional mechanical expansion technology. Through experiments, the device analyzes and verifies the parameters of the copper tube's internal thread size, diameter, length shrinkage, fin spacing, and hydraulic loading path after hydraulic expansion. The experiments show that the dimensions of the heat exchanger expanded using the equipment and method of this invention meet the standard process requirements and satisfy the qualified production standards for heat exchangers.

[0064] like Figure 17 and Figure 18 As shown, a comparison of the effects of the heat exchanger expanded using the device and method of the present invention (left) and the heat exchanger expanded using the prior art (right) shows that the heat exchanger expanded using the device and method of the present invention has better consistency in the diameter of the heat exchange copper tubes, while the heat exchange copper tubes expanded by the traditional hydraulic expansion method will show varying degrees of diameter deformation and overall bending.

[0065] This invention utilizes high-pressure hydraulic fluid to uniformly expand and connect heat exchange copper tubes. The force transmission medium is high-pressure liquid fluid, which significantly improves the expansion quality, eliminates damage to the internal threads of the copper tube caused by mechanical expansion rods and heads, effectively prevents irregular deformation and bending of slender heat exchange copper tubes under high-pressure liquid, and increases the liquid flow rate at the U-end of the heat exchange tube, further enhancing heat exchange efficiency. Even for small-diameter (φ≤5mm) internally threaded copper tubes in air conditioning heat exchangers, reliable expansion and connection can be easily achieved, demonstrating excellent benefits.

[0066] All aspects not detailed in this invention are conventional technical means known to those skilled in the art.

[0067] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0068] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger, used for the expansion joint of U-shaped heat exchange copper tubes (91), characterized in that, The device includes a first clamping mechanism, a second clamping mechanism, and a hydraulic mechanism (7) located on the device platform (1); the first clamping mechanism clamps the bent section (92) of the heat exchange copper tube (91); the second clamping mechanism clamps the straight section of the heat exchange copper tube (91); the hydraulic mechanism (7) includes at least one set of hydraulic expansion terminals (10), the hydraulic expansion terminals (10) include two expansion joints (101) connected to the open ends of the two straight sections of the heat exchange copper tube (91), the expansion joints (101) are detachably connected to an internal mandrel (8) that can be inserted into the straight section of the heat exchange copper tube (91), and the two expansion joints (101) are connected to the same hydraulic power device; The built-in mandrel (8) is a hollow tube with several through holes (82) evenly opened on its body, and the length of the built-in mandrel (8) is consistent with the length of the straight section of the U-shaped heat exchange copper tube (91). The expansion joint (101) has a threaded hole in the center, and a through bolt (102) is threaded into the threaded hole. The through bolt (102) has a hole at its axial center to accommodate the heat exchange copper tube (91). One end of the built-in mandrel (8) is provided with a base. The end of the built-in mandrel (8) with the base is inserted into the threaded hole, and a sealing washer (103) is fitted over the built-in mandrel (8). After the heat exchange copper tube (91) passes through the hole of the through bolt (102), the through bolt (102) is screwed into the threaded hole. The sealing washer (103) is deformed by compression and presses against the base of the built-in mandrel (8).

2. The device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to claim 1, characterized in that, The built-in mandrel (8) is made of stainless steel hollow tube.

3. The device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to claim 1, characterized in that, The first clamping mechanism and the second clamping mechanism are detachably connected to the device platform (1).

4. The device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to claim 1, characterized in that, The hydraulic mechanism (7) is slidably connected to the device platform (1) in a direction perpendicular to the heat exchange copper tube (91).

5. The device for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to claim 4, characterized in that, The hydraulic mechanism (7) also includes a hydraulic distributor (78) that reciprocates along the length of the heat exchange copper tube (91).

6. A method for improving the quality of hydraulic expansion joints in tube-fin heat exchangers, characterized in that, An apparatus for improving the hydraulic expansion joint quality of a tube-fin heat exchanger according to any one of claims 1 to 5, the method comprising the following steps: Step 1: Fix the heat exchanger onto the hydraulic expansion joint device of the riser fin heat exchanger; Step 2: Insert the built-in mandrel (8) into the heat exchange copper tube (91) from the open end of the heat exchange copper tube (91), and seal the heat exchange copper tube (91) onto the hydraulic expansion terminal (10); Step 3: Start the hydraulic mechanism (7), inject hydraulic oil into the heat exchange copper tube (91) through the built-in mandrel (8) and pressurize it so that the hydraulic oil acts evenly on the inner surface of the heat exchange copper tube (91). Under the pressure of the hydraulic oil, the heat exchange copper tube (91) undergoes plastic deformation and expands evenly. Step 4: Repeat steps 2 and 3 to complete the expansion connection of the other heat exchange copper tubes (91) in the heat exchanger.

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