Welding device and heat exchange tube manufacturing equipment

Abstract

The utility model relates to the technical field of heat exchange tube machining and manufacturing, in particular to a welding device and heat exchange tube manufacturing equipment. The welding device is used for welding a butt joint part of a cylindrical steel strip, and comprises a driving unit for driving the steel strip to move towards the front side; the welding unit is used for welding the butt joint part to form a welding seam; and a core rod which is arranged at the inner part of the cylindrical shape and the front side of the welding unit and is used for shaping the welding seam in a manner of extruding the welding seam outwards from the inner side of the cylindrical shape. Therefore, the welding seam formed on the cylindrical steel belt by utilizing the welding unit can pass through the core rod, and the core rod outwards extrudes the solidified welding seam in the cylindrical steel belt, so that the welding seam is shaped, and bulges on the inner side of the welding seam are leveled, thereby being beneficial to improving the quality of the inner surface of a finished steel pipe; the heat exchange tube can be easily processed into a heat exchange tube with high heat exchange efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of heat exchange tube processing and manufacturing, and in particular to a welding device and heat exchange tube manufacturing equipment. Background Art

[0002] The steel strip is the base material for processing the tube blank of the stainless steel heat exchange tube. In the related art, the steel strip is squeezed and deformed into a cylindrical shape with a butt joint by a forming unit, and then the butt joint of the cylindrical steel strip is welded by a laser welding device, so that the fine seam of the butt joint is closed to form a steel tube as the tube blank of the stainless steel heat exchange tube.

[0003] In the above-mentioned related technologies, laser welding uses a high-energy-density laser beam as a heat source to melt the cylindrical steel strip at the butt joint through heat conduction to form a specific molten pool, thereby obtaining a sealed weld. However, the weld formed by welding will present uneven burrs. If the burrs cannot be effectively removed, it will significantly increase the difficulty of processing it into a heat exchange tube and affect the heat exchange efficiency of the heat exchange tube made of it. Summary of the invention

[0004] The purpose of the present application is to solve at least one of the above-mentioned technical problems and to provide a welding device and a heat exchange tube manufacturing equipment.

[0005] In a first aspect, the present application provides a welding device for welding a butt joint of a steel strip formed into a cylindrical shape, the welding device comprising:

[0006] A driving unit, which drives the steel belt to move toward the front side;

[0007] A welding unit, which welds the butt joint to form a weld;

[0008] A mandrel is arranged inside the cylinder and in front of the welding unit, and shapes the weld seam in such a manner that the weld seam is pressed outward from the inside of the cylinder.

[0009] In some possible implementations, the core rod is in close contact with the cylindrical inner surface over the entire circumference.

[0010] In some possible implementations, the rear end surface of the mandrel has a rounded corner surrounding the rear end surface.

[0011] In some possible implementations, the following further includes:

[0012] Limiting parts,

[0013] a flexible member disposed inside the cylindrical shape and connecting the core rod to the stopper;

[0014] The limiting member prevents the core rod from following the steel strip and moving toward the front side by pulling the core rod via the flexible member.

[0015] In some possible implementations, the stopper includes a cable having an inner end extending into the interior of the cylinder and an outer end extending out of the exterior of the cylinder;

[0016] The position of the outer end portion is adjustable, thereby making the position of the core rod adjustable in the front-rear direction.

[0017] In some possible implementations, the following further includes:

[0018] A pair of pressing rollers includes a first roller and a second roller which are respectively arranged on both sides of the mandrel in a radial direction and press the cylindrical shape toward the mandrel at the outside of the cylindrical shape.

[0019] In some possible implementations, the first roller presses the weld toward the mandrel in a manner facing the weld.

[0020] In some possible implementations, at least one of the first roller and the second roller is a powered roller, and the powered roller applies a driving force toward the front side to the steel strip.

[0021] In some possible embodiments, the first roller and the second roller are configured to roll back and forth between the two ends of the mandrel along the front-to-back direction, and during the rolling process, the first roller presses the weld toward the mandrel in a manner facing the weld.

[0022] In a second aspect, the present application also provides a heat exchange tube manufacturing device, comprising the welding device as described in the first aspect.

[0023] The welding device provided by the present application is used to weld the butt joint of a steel strip formed into a cylindrical shape, and includes: a driving unit for driving the steel strip to move toward the front side; a welding unit for welding the butt joint to form a weld; a mandrel arranged inside the cylinder and on the front side of the welding unit, and shaping the weld by squeezing the weld from the inside of the cylinder to the outside. With this structure, in practice, the weld formed on the cylindrical steel strip by the welding unit will then pass through the mandrel, and the mandrel squeezes the still solidified weld outward inside the cylindrical steel strip to shape the weld, and the protrusion (or burr) inside the weld is flattened, which helps to improve the surface quality of the finished steel pipe (tube blank of the heat exchange tube), so that it can be easily processed into a heat exchange tube with high heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present application, rather than limiting the present application.

[0025] Figure 1 It is a three-dimensional schematic diagram of a welding device provided in an embodiment of the present application in a working state.

[0026] Figure 2 yes Figure 1 sectional view of .

[0027] Figure 3 yes Figure 2 Partial enlargement.

[0028] Figure 4 yes Figure 1 Schematic diagram of the structure after the steel belt and the pressure roller are removed.

[0029] Figure 5 yes Figure 1 Three-dimensional structural view of the connecting parts.

[0030] Figure 6 yes Figure 1 Schematic diagram of top view of the connecting parts.

[0031] Figure 7 yes Figure 6 AA section diagram of .

[0032] Figure 8 yes Figure 1 Structural view of the core rod.

[0033] Description of reference numerals:

[0034] T-steel strip, T1-butt joint, T2-weld;

[0035] G1-first pair of pressing rollers, G2-second pair of pressing rollers, G3-third pair of pressing rollers, G4-fourth pair of pressing rollers;

[0036] 1- first seal;

[0037] 2-second sealing member, 2A-through hole;

[0038] 3- Welding unit;

[0039] 4-connecting piece, 4A-exhaust port, 4B-air passage, 4B1-ventilation seam, 4C-additional exhaust port, 4D-additional air passage, 4D1-additional ventilation seam;

[0040] 5-mandrel, 5A-rounded corners;

[0041] 6- flexible member;

[0042] 7-Connecting rod;

[0043] 8-Ropes;

[0044] 9-First cavity

[0045] 10-Second cavity;

[0046] 11- first roller;

[0047] 12- second roller;

[0048] 13- guide wheel;

[0049] 14-Trachea. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the embodiment of the present application will be clearly and completely described below in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, rather than all the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of this application. It can be understood that, in the absence of conflict, some technical means of the various embodiments described herein can be replaced or combined with each other.

[0051] In the description of this application, if there are terms such as "first", "second", etc., they are only used to distinguish the objects described and do not have any order or technical meaning. Therefore, an object defined as "first", "second", etc. may explicitly or implicitly include one or more of the objects, and, for example, the term "first element" itself does not mean the existence of the "second element", and the term "second element" itself does not mean the existence of the "first element". In addition, "one" or "a" and similar words do not indicate a quantity limitation, but rather indicate the existence of at least one, and "multiple" means not less than two.

[0052] In the description of this application, the terms "including", "having" indicate the existence of the features, numbers, operations, elements and / or their combinations, but do not exclude the existence or addition of one or more other features, numbers, operations, elements and / or their combinations. For example, "the battery pack includes two cells, each of which has a feature S", which means that the battery pack includes at least two cells each having the feature S. Obviously, this does not exclude that the battery pack may also include a third cell that does not have the feature S, nor does it exclude that the battery pack may also include a fourth cell that also has the feature S.

[0053] In the description of the present application, reference to "one embodiment" or "some embodiments" etc. means that one or more embodiments of the present application include a particular feature, structure or characteristic described in conjunction with the embodiment. Thus, the phrases "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. appearing in different places in the present specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways.

[0054] Figures 1 to 8 A welding device provided in an embodiment of the present application is shown, which is used to weld the butt joint T1 of a steel strip T formed into a cylindrical shape, so as to close the gap of the butt joint T1, thereby obtaining a welded steel pipe with a weld seam T2 (corresponding to the butt joint T1). Figure 1 In the axial direction, the aforementioned cylindrical shape (abbreviation of "cylindrical steel strip T") extends front to back.

[0055] See also Figure 1 , the first pair of rollers G1, the second pair of rollers G2, the third pair of rollers G3 and the fourth pair of rollers G4 are arranged in order from back to front on both sides of the radial direction of the cylindrical steel strip T. In practice, the cylindrical steel strip T (where the gap of the butt joint T1 of the cylindrical steel strip T is relatively large) coming from the upstream side (i.e., the rear side) of the first pair of rollers G1 is squeezed and shaped by the first pair of rollers G1 to reduce the gap of the butt joint T1. When the cylindrical steel strip T squeezed and shaped by the first pair of rollers G1 passes forward through the second pair of rollers G2, it is further squeezed and shaped by the second pair of rollers G2 to further reduce the gap of the butt joint T1. The third pair of rollers G3 is arranged at the welding unit 3 described later, and is used to make the two edges of the steel strip T fit closely at the butt joint T1 when the welding unit 3 welds the butt joint T1, so as to ensure the welding quality. The fourth pair of pressing rollers G4 is arranged at the mandrel 5 described later, and is used to eliminate burrs on the weld T2 by rolling to improve the flatness of the outer surface of the finished steel pipe, so that it can be easily processed into a stainless steel heat exchange tube with high heat exchange efficiency.

[0056] The welding device includes a driving unit, a first sealing member 1 , a second sealing member 2 , a shielding gas source and a welding unit 3 .

[0057] The illustration of the driving unit is omitted, and the driving unit is used to drive the steel strip T to move toward the front side. In some embodiments, the driving unit includes a plurality of power roller groups, which are arranged in front of the fourth pair of rollers and are spaced apart from each other. The power roller groups roll and squeeze the outer surface of the welded portion of the cylindrical steel strip T so that the steel strip T moves in a forward direction. Figure 1 The Chinese Super League moves to the front.

[0058] The first sealing member 1 is arranged inside the tubular steel strip T and is in sealing contact with the inner surface of the tubular steel strip T.

[0059] The second seal 2 is arranged inside the cylindrical steel belt T and is in sealing contact with the inner surface of the cylindrical steel belt T. In addition, the second seal 2 is arranged at a distance from the rear side of the aforementioned first seal 1, so that a first cavity 9 surrounded by the inner surface of the cylindrical steel belt T is formed between the first seal 1 and the second seal 2. The outer peripheral surface of the first seal 1 and the outer peripheral surface of the second seal 2 can be formed of Teflon, rubber or silicone.

[0060] The illustration of the shielding gas source is also omitted, and the shielding gas is provided to the first cavity 9 via the second seal 2. Here, providing shielding gas to the first cavity 9 via the second seal 2 means that the shielding gas provided by the shielding gas source to the first cavity 9 flows at least through the second seal 2. The shielding gas can provide oxygen exhaust protection for the welding of the butt joint T1 of the steel strip T, and prevent the welding part of the steel strip T from being oxidized at high temperature. The shielding gas can be argon or nitrogen.

[0061] The welding unit 3 welds the butting portion T1 at the first cavity 9 to form a weld T2 , and the welding unit 3 may be a laser welding unit.

[0062] In practice, the shielding gas source continuously provides shielding gas to the first cavity 9 of limited volume and length through the second seal 2, and the shielding gas is discharged outward through the tiny gap of the docking portion T1 at the first cavity 9, thereby forming an oxygen-free protective space around the docking portion T1 at the first cavity 9, and the welding unit 3 welds the docking portion T1 of the tubular steel strip T in the protective space, which helps to improve the welding quality and has strong operability. Compared with the entire tubular steel strip T, the volume and length of the first cavity 9 are smaller, and the gap of the docking portion T1 at the first cavity 9 is relatively short, so the shielding gas source only needs to provide a small flow of shielding gas to form a good protective space at the welding site.

[0063] In some embodiments, the length of the first cavity 9 in the front-to-back direction is less than 30 centimeters.

[0064] See also Figures 2 to 7 The connecting member 4 connects the first sealing member 1 and the second sealing member 2 in the first cavity 9, and has an exhaust port 4A connected to the protective gas source, and the exhaust port 4A is formed into a long structure extending in the front-to-back direction. In this way, the exhaust port 4A of the long structure can supply gas to various parts of the first cavity 9 as much as possible, thereby helping to make the gap of the docking portion T1 at the first cavity 9 receive the protective gas over the entire length.

[0065] Furthermore, the exhaust port 4A is configured to exhaust gas toward the butt joint T1 of the first cavity 9. It is understandable that the long exhaust port 4A is configured to exhaust gas toward the butt joint T1 of the first cavity 9, which can further improve the filling degree of the gap of the butt joint T1 with the protective gas.

[0066] See also Figure 3 In this embodiment, the front end of the connector 4 is detachably fixed to the first seal 1 via a bolt whose reference numeral is omitted, and the rear end of the connector 4 is detachably fixed to the second seal 2 via another bolt whose reference numeral is omitted. The connector 4 has an air passage 4B extending from the rear end face of the connector 4 in the front-to-back direction, and the second seal 2 has a through hole 2A penetrating in the front-to-back direction, and the air pipe 14 drawn out from the protective gas source is inserted into the through hole 2A and communicated with the air passage 4B.

[0067] The air passage 4B has an air slit 4B1 extending over the entire length of the exhaust port 4A and located on the inner side of the exhaust port 4A. In this way, the air passage 4B can be connected to the exhaust port 4A over the entire length of the exhaust port 4A through the air slit 4B1. In addition, since the ventilation area of ​​the narrow air slit 4B1 is small, the protective gas from the air pipe 14 can fill the air passage 4B well and flow to the exhaust port 4A through the entire length of the air slit 4B1, so that the exhaust port 4A can supply the protective gas to the joint of the steel strip T within its entire length, which helps to improve the coverage of the protective gas to the welding space. In addition, there are two air passages 4B, so there are correspondingly two air slits 4B1. On the side facing the exhaust port 4A (i.e. Figure 3 When viewed from the bottom (in the downward direction), the two air passages 4B are symmetrically arranged on both sides of the exhaust port 4A, and therefore, the two air permeable slits 4B1 are also symmetrically arranged on both sides of the exhaust port 4A. In this way, the protective gas in the two air passages 4B enters the exhaust port 4A in a symmetrical manner, which can prevent the exhaust direction of the exhaust port 4A from being offset, for example, preventing the exhaust direction of the exhaust port 4A from being offset. Figure 3 The welding device is also provided with a mandrel 5, which is arranged inside the cylindrical steel strip T and in front of the first sealing member 1, and is in close contact with the inner surface of the cylindrical steel strip T over the entire circumference.

[0068] In practice, when the welding unit 3 welds the butt joint T1 at the first cavity 9 and just forms the weld T2, both the inner and outer surfaces of the tubular steel strip T will present uneven high-temperature burrs at the weld T2. When the weld T2 with burrs follows the tubular steel strip T and moves forward to the position of the core rod 5, the core rod 5 squeezes the weld T2 from the inside to flatten the burrs on the inner surface, thereby improving the flatness of the inner surface of the finished steel pipe.

[0069] See also Figure 8 Combined with Figure 2The rear end face of the mandrel 5 has a rounded corner 5A surrounding the rear end face. The rounded corner 5A allows the welding burrs on the inner surface of the tubular steel strip T to smoothly enter the peripheral portion of the mandrel 5, thereby preventing the rear end face of the mandrel 5 from scratching the tubular steel strip T, and in particular, preventing the rear end face of the mandrel 5 from scraping off the welding burrs on the inner surface of the tubular steel strip T and reducing the connection strength at the weld T2.

[0070] The stopper is connected to the mandrel 5, and is configured to prevent the mandrel 5 from moving forward following the steel strip T. By connecting the stopper to the mandrel 5, the position of the mandrel 5 can be kept unchanged during the movement of the cylindrical steel strip T toward the front, which helps to improve the operability of the weld shaping. The mandrel 5 is spaced apart from the first sealing member 1 by a certain arrangement, so that a second cavity 10 surrounded by the inner surface of the cylindrical steel strip T is formed therebetween, and the mandrel 5 is connected to the stopper via a flexible member 6 arranged in the second cavity 10. The stopper prevents the mandrel 5 from moving forward following the steel strip T by pulling the mandrel 5 via the flexible member 6. In this way, based on the flexural deformation of the flexible member 6, the position of the mandrel 5, especially in the radial direction, can float and change within a specified range following the cylindrical steel strip T, thereby avoiding the following problem: when the cylindrical steel strip T is radially offset at the position of the mandrel 5 due to shaking or other factors, if the position of the mandrel 5 is fixed, it may cause the cylindrical steel strip T to produce undesirable deformation.

[0071] The mandrel 5 is located at a distance in front of the welding unit 3, so that the weld T2 formed on the tubular steel strip T by the welding unit 3 will then pass through the mandrel 5, and the mandrel 5 presses the unsolidified weld T2 outward inside the tubular steel strip T, thereby shaping the weld T2 (the inner configuration).

[0072] The aforementioned limiting member includes a cable 8 and two connecting rods 7. Each connecting rod 7 is slidably connected to the first seal 1, the connecting member 4 and the second seal 2 in the front-to-back direction inside the cylindrical steel belt T. One end of the flexible member 6 is connected to the front end portions of the two connecting rods 7, and the other end is connected to the rear end portion of the core rod 5. One end of the cable 8 is connected to the rear end portions of the two connecting rods 7 inside the cylindrical steel belt T, and the other end of the cable 8 extends out of the cylindrical steel belt T through (the gap of) the docking portion T1. The guide wheel 13 shown in dotted lines (the guide wheel 13 is omitted in other drawings) guides the cable 8 into a bend of approximately 90° at the gap of the docking portion T1. In addition, the position of the aforementioned other end of the cable 8 can be adjusted, so that the position of the other end of the cable 8 can be adjusted (such as, Figure 1 The position of the mandrel 5 in the front-rear direction is changed by adjusting the height of the other end of the middle rope 8 so that the mandrel 5 is adapted to the position of the fourth pair of pressure rollers.

[0073] The connector 4 also has an additional exhaust port 4C and two additional air passages 4D, wherein the additional exhaust port 4C and the two additional air passages 4D are symmetrically arranged with the aforementioned exhaust port 4A and the aforementioned two air passages 4B. When observing facing the exhaust port 4A, the exhaust port 4A and the additional exhaust port 4C completely overlap with each other, one of the air passages 4B and one of the additional air passages 4D completely overlap with each other, and the other air passage 4B and the other additional air passage 4D completely overlap with each other. The two connecting rods 7 can be slidably inserted into the two additional air passages 4D, respectively, so as to block the additional air passages 4D to a certain extent. In this way, when the exhaust port 4A or the air passage 4B of the connector 4 fails, the operator can connect the connector 4 to the Figure 3 The additional exhaust port 4C and the additional air passage 4D are rotated 180 degrees in the front-to-back direction, and the positions of the additional exhaust port 4C and the additional air passage 4D are swapped with the exhaust port 4A and the air passage 4B.

[0074] The stopper is connected to the mandrel 5 and the connector 4, and is configured to prevent the mandrel 5 and the connector 4 from moving forward following the steel strip T. By connecting the stopper to the mandrel 5 and the connector 4, the mandrel 5 and the connector 4, and thus the first seal 1 and the second seal 2, can be kept in position during the movement of the cylindrical steel strip T toward the front, thereby making the relative positions of the two seals and the welding unit 3 and the relative positions of the two seals and the mandrel 5 stable and unchanged, which helps to improve the operability of the welding operation and the operability of the weld shaping.

[0075] In some embodiments, the second sealing member 2 is pulled by the air pipe 14 with high structural strength to prevent the first sealing member 1, the connecting member 4 and the second sealing member 2 from moving forward following the steel strip T. In this way, the relative positions of the two sealing members and the welding unit 3 can be kept stable during the operation, which helps to improve the operability of the welding operation.

[0076] In other embodiments, an additional rope connected to the second seal 2 is configured, and the first seal 1, the connecting member 4 and the second seal 2 are prevented from following the steel belt T and moving toward the front by pulling the second seal 2 with the additional rope.

[0077] In other embodiments, the aforementioned connecting rod 7 is fixedly connected to the connecting member 4 via a top screw, so that the aforementioned limiter composed of the connecting rod 7 and the cable 8 pulls the connecting rod 7 to prevent the first sealing member 1, the connecting member 4 and the second sealing member 2 from moving forward following the steel strip T. The disadvantage is that the relative distance between the first cavity 9 and the mandrel 5 cannot be flexibly adjusted during the welding operation.

[0078] The flexible member 6 is fixedly connected to the connecting member 4 via a jackscrew (not shown) in the middle of the connecting rod 7. One end of the flexible member 6 is connected to the front end of the two connecting rods 7, and the other end is connected to the rear end of the core rod 5.

[0079] One end of the cable 8 is connected to the rear end of the two connecting rods 7 inside the cylindrical steel belt T, and the other end of the cable 8 extends out of the cylindrical steel belt T through the (slit of) the butt joint T1. The guide wheel 13 shown in dotted lines (the guide wheel 13 is omitted in other drawings) guides the cable 8 into a substantially 90° bend at the gap of the butt joint T1. In addition, the position of the aforementioned other end of the cable 8 can be adjusted, so that the position of the other end of the cable 8 (such as Figure 1 The positions of the first sealing member 1, the connecting member 4 and the second sealing member 2 relative to the welding unit 3 are changed by adjusting the height of the other end of the middle cable 8, so that the butt joint T1 at the first cavity 9 and the welding unit 3 are adapted to each other in position.

[0080] In this embodiment, the aforementioned rope 8 and the flexible member 6 are both steel wire ropes.

[0081] The fourth pair of pressing rollers G4 includes a first roller 11 and a second roller 12 which are respectively arranged on both sides of the mandrel 5 in the radial direction and press the cylindrical steel strip T toward the mandrel 5 on the outside of the cylindrical steel strip T. In addition, the first roller 11 presses the weld T2 toward the mandrel 5 in a manner facing the weld T2 (i.e., the butt joint T1 after welding). In this way, the inner mandrel 5 and the outer first roller 11 squeeze the inner and outer sides of the weld T2 respectively, so that the burrs on the inner and outer sides of the weld T2 are effectively trimmed, which helps to improve the flatness of the inner and outer surfaces of the finished steel pipe and the connection strength at the weld T2.

[0082] In some embodiments, at least one of the first roller 11 and the second roller 12 is a powered roller that applies a driving force to the tubular steel strip T toward the front side.

[0083] In some embodiments, the first roller 11 and the second roller 12 are configured to roll back and forth between the two ends of the mandrel 5 in the front-rear direction, and during the rolling process, the first roller 11 always keeps pressing the tubular steel strip T, especially the weld T2. In this way, the weld can be better shaped.

Claims

1. A welding device for welding a butt joint of a steel strip formed into a cylindrical shape, characterized in that: The welding device comprises: A driving unit, which drives the steel belt to move toward the front side; A welding unit, which welds the butt joint to form a weld; A mandrel is arranged inside the cylinder and in front of the welding unit, and shapes the weld seam in such a manner that the weld seam is pressed outward from the inside of the cylinder.

2. The device according to claim 1, characterized in that The core rod is in abutting contact with the cylindrical inner surface over the entire circumference.

3. The device according to claim 2, characterized in that The rear end face of the mandrel has a rounded corner surrounding the rear end face.

4. The device according to claim 1, characterized in that Also includes: Limiting parts, a flexible member disposed inside the cylindrical shape and connecting the core rod to the stopper; The limiting member prevents the core rod from following the steel strip and moving toward the front side by pulling the core rod via the flexible member.

5. The device according to claim 4, characterized in that The stopper comprises a cable having an inner end extending into the interior of the cylinder and an outer end leading out of the exterior of the cylinder; The position of the outer end portion is adjustable, thereby making the position of the core rod adjustable in the front-rear direction.

6. The device according to any one of claims 1 to 5, characterized in that Also includes: A pair of pressing rollers includes a first roller and a second roller which are respectively arranged on both sides of the mandrel in a radial direction and press the cylindrical shape toward the mandrel at the outside of the cylindrical shape.

7. The device according to claim 6, characterized in that The first roller presses the weld seam toward the mandrel in a manner facing the weld seam.

8. The device according to claim 6, characterized in that At least one of the first roller and the second roller is a power roller, and the power roller applies a driving force toward the front side to the steel strip.

9. The device according to claim 6, characterized in that The first roller and the second roller are configured to roll back and forth between both ends of the mandrel in the front-rear direction, and during the rolling, the first roller keeps facing the weld seam to press the weld seam toward the mandrel.

10. A heat exchange tube manufacturing device, characterized in that: Comprising the welding device according to any one of claims 1 to 9.

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