Ultra-thin stainless steel combined welding cooling forming method and production line

Abstract

The present application discloses a method for ultra-thin stainless steel combined welding and cooling forming, which relates to the field of stainless steel welding technology, including: preheating the welding portion of the stainless steel part to be welded; secondary heating the welding portion of the stainless steel part that has completed preheating, so that the welding portion of the stainless steel part is partially melted; while secondary heating, the stainless steel part is squeezed so that the partially melted area of the welding portion is welded and fused; the force of squeezing the stainless steel part is maintained, and kept for a period of time until the welding portion of the stainless steel part is cooled; the preheating heating temperature is maintained in a temperature range where the welding portion of the stainless steel part does not melt and does not affect the strength of its matrix. Such a process ensures the strength of the pipe while reducing the inner wall welding slag, does not require too much resource to clean, and improves the performance of the product. In addition, an ultra-thin stainless steel combined welding and cooling forming production line that improves the above method is also disclosed. The production line has a simple structure, high efficiency, and stable operation.

Description

Technical Field

[0001] The present application relates to the technical field of stainless steel welding, and in particular to an ultra-thin stainless steel combined welding cooling forming method and a production line thereof. Background Art

[0002] The biggest challenge facing high-frequency induction welding of stainless steel pipes is the impact of oxides on quality. Due to the high alloy content of stainless steel, a large amount of oxides is generated if the weld area is exposed to air during high-frequency welding. While most of the oxides are squeezed out by the extrusion rollers, a small amount may remain in the weld, causing weld inclusion defects. Because the melting point of iron oxides (FeO: 1420°C; Fe2O3: 1565°C) is lower than or close to the melting point of elemental iron (1537°C), when welding carbon steel pipes, the oxides melt before or at the same time as the base material, making oxide removal easier. However, the situation is different when welding stainless steel pipes. Both chromium and nickel-based stainless steels suffer from the problem of oxides melting at a higher temperature than the base material. When the content of chromium (Cr) in stainless steel exceeds 12%, chromium preferentially combines with oxygen over iron, forming a dense oxide film on the base material surface. Cr2O3 has a melting point of 2265°C, while chromium has a melting point of 1857°C. The melting point of nickel oxide (NiO) (2090°C) is also much higher than that of nickel (1446°C). Therefore, oxides in the weld and their removal are critical factors affecting stainless steel pipe welding. During the welding of thin stainless steel, due to the material's thinness, the stainless steel itself begins to melt at the edge when heated, but the oxide layer remains, making extrusion impossible. If the melting temperature is further increased, the substrate will carbonize to further melt the oxide layer, and the hydrogen released will cause explosions and material collapse. This is a difficult problem that traditional processes have difficulty in overcoming when welding thin stainless steel. Summary of the Invention

[0003] To solve the above problems, the present application provides an ultra-thin stainless steel combined welding cooling forming method, comprising the following steps:

[0004] S1. Preheating the welding portion of the stainless steel parts to be welded by a first heating device;

[0005] S2, secondary heating the preheated welded portion of the stainless steel member by a second heating device, so that the welded portion of the stainless steel member is partially melted;

[0006] S3. While performing secondary heating, the stainless steel member is extruded so that the partially melted area of the weld is welded and fused;

[0007] S4. Maintain the force of squeezing the stainless steel part for a period of time until the welded part of the stainless steel part cools down;

[0008] The preheating temperature is maintained within a temperature range where the welded portion of the stainless steel part does not melt and does not affect the strength of its matrix; the purpose of setting the preheating is to be able to pre-increase the temperature of the stainless steel part, which is conducive to subsequent secondary heating for rapid and accurate heating and welding.

[0009] The heating temperature of the secondary heating is equal to or higher than the melting point temperature of the oxide film on the outer surface of the weld. The second heating device heats the weld that has been preheated for secondary heating. This heating should reach the melting point temperature of the oxide film on the outer surface of the weld to destroy its structure. Since the melting point of the oxide film on the surface of stainless steel is higher than the melting point of the substrate, after the oxide film is melted, the side part of the substrate close to the melted oxide film is also melted. At this time, the oxide can be squeezed out by squeezing the stainless steel part, and at the same time, the two sides of the stainless steel part that need to be welded can be welded and fused. Since the material of the inner wall of the stainless steel part is not melted, it still has sufficient mechanical strength to support the molten pool formed on its upper part and will not penetrate. Therefore, there is very little oxide on its bottom surface, and there is no need to spend a lot of manpower, material resources and time to clean it up later, which greatly improves the performance of the welding product.

[0010] Preferably, the first heating device is a high-frequency heating device; the high-frequency heating device can directly introduce traditional high-frequency induction welding technology, and use the high-frequency coil to heat the stainless steel parts by the skin effect and proximity effect. Among them, the skin effect is that when an alternating current flows through a conductor, the current distribution in the conductor is more on the surface and less in the center. This high-frequency current only flows along the surface layer. It is caused by the action of the magnetic field inside the conductor. The strength of the skin effect mainly depends on the frequency of the high-frequency current. The higher the current frequency, the greater the internal inductance of the conductor, and the stronger the skin effect. The proximity effect refers to the property that if two conductors with high-frequency current flowing through them are very close to each other, the high-frequency current will only flow along the adjacent side of the two conductors (when the current directions in the two conductors are opposite) or the farther side (when the current directions in the two conductors are the same).

[0011] The second heating device is a laser heating device; the laser welding method is adopted here mainly because laser welding can quickly increase the temperature of a certain area and is easy to control, which is very consistent with the requirements of this application for quickly melting the stainless steel oxide layer but not completely melting the stainless steel.

[0012] The stainless steel part is subjected to mechanical force and sequentially passes through a first heating device and a second heating device, and is finally extruded and cooled.

[0013] Preferably, the partial melting depth is between 80% and 95% of the thickness of the stainless steel part. To address the issue of weld slag on the inner wall material, high-frequency welding heating is primarily used, with parameters adjusted to ensure the melting temperature and the affected edge zone. Laser welding is used as a supplement to ensure energy concentration at the welding location, sufficiently heating the outer material to prevent melting of the inner layer. During extrusion, the weld slag is turned outward and subsequently scraped to resolve the issue.

[0014] Preferably, the partial melting depth accounts for 90% of the thickness of the stainless steel part. This 90% melting depth, meaning the innermost 10% of the thickness remains unmelted, represents the optimal value obtained through extensive experimentation. It maximizes the mechanical properties of the stainless steel weldment while ensuring the cleanliness of its inner wall.

[0015] Preferably, the cross section of the partially melted stainless steel piece is V-shaped, that is, the molten pool is V-shaped, and the bottom of the molten pool is the unmelted part, which plays a role in supporting the molten pool and strengthening the connection.

[0016] Preferably, during steps S1 through S4, the stainless steel workpiece is immersed in a coolant. Because the stainless steel workpiece is very thin, only 0.2 to 0.1 mm, additional cooling is required to accelerate heat dissipation and maintain only partial melting of the welded portion. Coolant is an effective method for this purpose. Furthermore, immersing the stainless steel workpiece in the coolant reduces contact with air and reduces oxidation.

[0017] Preferably, the coolant is an emulsion. The emulsion has the ability to prevent oxidation of the workpiece during welding, while reducing the heat away from the edge of the material, further reducing the generation of oxides and improving product quality.

[0018] Preferably, a stainless steel part pre-deformation step is further included before step S1, wherein the stainless steel part pre-deformation step can bend the stainless steel part into a desired shape using a pressing roller or a roller.

[0019] The present application provides a method for ultra-thin stainless steel combined welding and cooling forming, which includes: S1 preheating the welding portion of the stainless steel workpiece to be welded; S2, secondary heating the welding portion of the stainless steel workpiece that has completed the preheating, so that the welding portion of the stainless steel workpiece is partially melted; S3, while secondary heating, extruding the stainless steel workpiece so that the partially melted area of the welding portion is welded and fused; S4, maintaining the force of squeezing the stainless steel workpiece and keeping it for a period of time until the welding portion of the stainless steel workpiece cools; the preheating temperature is maintained in a temperature range where the welding portion of the stainless steel workpiece does not melt and does not affect the strength of its matrix. By adopting such a process, the oxide film on the outer surface of the stainless steel workpiece can be melted, and the side portion of the matrix close to the melted oxide film can also be melted. At this time, by extruding the stainless steel workpiece, the oxide can be squeezed out, and at the same time, the two sides of the stainless steel workpiece that need to be welded can be welded and fused. Since the material on the inner wall of the stainless steel part is not melted, it still has sufficient mechanical strength to support the molten pool formed on its upper part without penetrating. Therefore, there is very little oxide on its bottom surface, and there is no need to spend a lot of manpower, material resources and time to clean it up later, which greatly improves the performance of the welded product.

[0020] In order to efficiently apply the above-mentioned ultra-thin stainless steel combined welding and cooling forming method, the present application provides an ultra-thin stainless steel combined welding and cooling forming production line comprising:

[0021] A steel belt conveying unit, comprising a conveying motor, for conveying the steel belt;

[0022] a preforming unit, which is fixedly arranged on one side of the steel strip conveying unit and is used to bend and preform the steel strip delivered by the steel strip conveying unit;

[0023] a welding unit, which is fixedly arranged on the other side of the preforming unit and is used to weld the preformed steel strip sent from the preforming unit;

[0024] a shaping unit, which is fixedly arranged on the other side of the welding unit, and includes a plurality of rollers arranged in parallel with each other, through which the stainless steel pipe welded by the welding unit passes;

[0025] The cooling unit is arranged below the welding unit and the shaping unit, and is used to cool the stainless steel pipes being welded or that have been welded but not completely shaped.

[0026] Preferably, the preforming unit includes a preforming unit bracket, two columns are vertically fixedly provided on the top of the preforming unit bracket, an upper pressing wheel shaft is horizontally provided between the two columns, and an upper pressing wheel is rotatably provided on the upper pressing wheel shaft; two side wheel shafts are also vertically fixedly provided on the top of the preforming unit bracket, and side pressing wheels are rotatably provided on the two side wheel shafts, and the steel belt passes between the two side pressing wheels and the upper pressing wheel. After being squeezed by the side pressing wheels and the upper pressing wheel, the steel belt is gradually squeezed into a cylindrical shape with an O-shaped cross section;

[0027] The side pressure wheel adopts an oblique side wheel structure;

[0028] The welding unit includes a welding unit bracket, on which a first heating device, a second heating device, a front pressure wheel, a rear pressure wheel and a welding extrusion wheel are fixedly arranged; the front pressure wheel is located on one side of the upper part of the welding unit bracket, the first heating device is arranged behind the front pressure wheel, the rear pressure wheel is arranged behind the first heating device, the welding extrusion wheel is arranged behind the rear pressure wheel, and the second heating device is fixedly arranged above the welding extrusion wheel; the front pressure wheel is close to the preforming unit, and the cylindrical steel strip fed from the preforming unit first enters the front pressure wheel, then enters the first heating device for heating, and then enters between the rear pressure wheel and the welding extrusion wheel. During this period, the weld of the steel strip is heated and melted by the second heating device, and the welding is completed by extrusion of the welding extrusion wheel.

[0029] The first heating device is a high-frequency heating device;

[0030] The second heating device is a laser heating device.

[0031] Another invention disclosed in this application is an ultra-thin stainless steel combined welding and cooling forming production line. This line optimizes and improves upon the existing high-frequency straight seam welded pipe production line. The preforming unit has been structurally optimized to achieve deformation and shape maintenance of highly elastic stainless steel strips. The welding unit has been significantly optimized, with the addition of a first heating device and a second heating device. The two heating units, combined with the welding extrusion wheel, weld the stainless steel pipe. Cooling and shaping are then performed using the shaping and cooling units, ultimately achieving the welding of ultra-thin stainless steel pipes. This production line features a rational design, ingenious structure, high efficiency, excellent stability, and ease of assembly and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of welding a 0.2 mm thick stainless steel plate according to Example 1 provided in this application;

[0033] Figure 2 yes Figure 1 A partial enlarged schematic diagram;

[0034] Figure 3 This is a schematic diagram of the structural framework of the production line of Example 2 provided in this application;

[0035] Figure 4 is a structural schematic diagram of a preforming unit;

[0036] Figure 5 It is a structural diagram of the welding unit;

[0037] Figure 6 It is a structural diagram of the pressure wheel;

[0038] Figure 7 It is a schematic diagram of the deformation process of the steel strip passing through the preforming unit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the embodiments of the present application. Figures 1 to 7 , the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the embodiments described are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present application. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the present application. In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present application.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0041] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0042] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0043] Example 1

[0044] In order to better introduce the ultra-thin stainless steel combined welding cooling forming method provided by this application, this embodiment takes the welding of ultra-thin stainless steel plate with a thickness of 0.2mm as an example to introduce its specific steps, such as Figure 1 As shown, the stainless steel parts are two plates with a thickness of 0.2 mm. The ends of the first workpiece 80 and the second workpiece 81 are against each other and are both subjected to inward pressure from both ends (in the direction of the arrows). During welding:

[0045] Step 1: Preheat the welded portion of the first workpiece 80 and the second workpiece 81 to be welded by a first heating device 31. The welded portion here refers to the edge portion where the workpieces contact each other. The heating method can be any form, such as electric wire heating, flame heating, electromagnetic eddy current heating, or laser heating. As long as the preheating temperature can be maintained within a temperature range where the welded portion of the stainless steel part does not melt and does not affect its matrix strength, the purpose of setting the preheating is to pre-increase the temperature of the stainless steel part, which is conducive to the subsequent secondary heating for rapid and accurate heating and welding.

[0046] Step 2: The welded parts of the first workpiece 80 and the second workpiece 81 of the stainless steel parts that have been preheated are heated for the second time by the second heating device 32, so that the welded parts of the stainless steel parts are partially melted. The requirements for the second heating device 32 here are relatively high. It needs to be able to quickly increase the temperature in a small area of the welded part of the stainless steel parts and accurately control the heat conduction. Therefore, the best choice here should be a laser heating device. After the ends of the first workpiece 80 and the second workpiece 81 are irradiated by the laser at the same time, the edge temperature of their ends increases rapidly on the basis of the heating by the first heating device 31, so that the temperature of the irradiated area can be quickly made equal to or higher than the melting point temperature of the oxide film on the outer surface of the welded part. The heat of the second heating device 32 should reach the melting point temperature of the oxide film on the outer surface of the welded part to destroy its structure. Since the melting point of the oxide film on the surface of stainless steel is higher than the melting point of the substrate, after the oxide film is melted, the part of the substrate close to the melted oxide film is also melted. As Figure 2 As shown, this is an enlarged schematic cross-sectional view of the weld, where a molten pool with a larger upper portion and a smaller lower portion is formed at the ends of the first workpiece 80 and the second workpiece 81 .

[0047] Step 3: While heating the stainless steel again, extrude the stainless steel so that the partially melted area of the weld is welded and fused. The extrusion direction is as follows: Figure 1 Direct the direction of the arrow shown. By squeezing the stainless steel part, the oxides are squeezed out, allowing the two sides of the stainless steel part to be welded together. Because the inner wall of the stainless steel part is not melted, it still has sufficient mechanical strength to prevent the molten pool formed on it from penetrating. As a result, there is very little oxide on the bottom surface, eliminating the need for labor-intensive and time-consuming cleaning later, greatly improving the performance of the welded product.

[0048] Step 4: Maintain the force of squeezing the stainless steel piece for a period of time until the welded part of the stainless steel piece cools down. To ensure the quality of the weld, a cooling step can be added.

[0049] Example 2

[0050] Taking the welding of ultra-thin stainless steel tubes with a wall thickness of 0.1~0.6mm as an example, the following detailed introduction is made to an ultra-thin stainless steel combined welding cooling forming method and an ultra-thin stainless steel combined welding cooling forming production line disclosed in this application. The welding processes for various thicknesses are the same, except that the corresponding laser power and feeding speed are slightly different.

[0051] Among them, such as Figure 3 As shown, an ultra-thin stainless steel combined welding and cooling forming production line includes a steel strip conveying unit 1, a preforming unit 2, a welding unit 3, a shaping unit 4 and a cooling unit 5, wherein:

[0052] The steel strip conveying unit 1 includes a conveying motor for conveying the steel strip. The structure of this part can refer to or apply the conveying structure of the existing high-frequency straight seam welded pipe production line.

[0053] The preforming unit 2 is fixedly arranged on one side of the steel strip conveying unit 1 and is used to bend and preform the steel strip 8 delivered by the steel strip conveying unit 1. Since the bending material is stainless steel, which has strong elasticity and high resilience, it is impossible to form the steel strip using only the existing high-frequency straight seam welded pipe production line structure. In order to solve the rebound of the thin stainless steel material during the forming stage, pre-deformation is achieved through the mold, and the distance between the roller and the welding station ensures the consistency of the position of the butt joint materials before welding. The specific plan is as follows Figure 7 As shown, the steel strip 8 is first bent into the structure shown in Figure 7A, then further bent into the structure shown in Figure 7B, and finally bent into the structure shown in Figure 7C before welding. The mechanical structure used is as follows Figure 4 As shown, the preforming unit 2 includes a preforming unit bracket 20, two columns 21 are vertically fixed on the top of the preforming unit bracket 20, an upper pressure wheel shaft 22 is horizontally arranged between the two columns 21, and an upper pressure wheel 23 is rotatably arranged on the upper pressure wheel shaft 22; two side wheel shafts 24 are also vertically fixed on the top of the preforming unit bracket 20, and side pressure wheels 25 are rotatably arranged on the two side wheel shafts 24, and a steel belt 8 passes between the two side pressure wheels 25 and the upper pressure wheel 23. After being extruded by the side pressure wheels 25 and the upper pressure wheel 23, the steel belt 8 is gradually extruded into a cylindrical shape with an O-shaped cross-section, wherein the side pressure wheel 25 adopts an inclined side wheel structure.

[0054] The welding unit 3 is fixedly arranged on the other side of the preforming unit 2 and is used to weld the preformed steel strip sent by the preforming unit 2. Figure 5 As shown, the welding unit 3 includes a welding unit bracket 30, on which a first heating device 31, a second heating device 32, a front pressure roller 33, a rear pressure roller 34, and a welding extrusion roller 35 are fixedly mounted. The front pressure roller 33 is located on one side of the welding unit bracket 30. The first heating device 31 is located behind the front pressure roller 33, the rear pressure roller 34 is located behind the first heating device 31, the welding extrusion roller 35 is located behind the rear pressure roller 34, and the second heating device 32 is fixed above the welding extrusion roller 35. In this embodiment, the first heating device 31 is a high-frequency heating device, and the second heating device 32 is a laser heating device. The front pressure roller 33 is adjacent to the preforming unit 2. The cylindrical steel strip 8 fed from the preforming unit 2 first enters the front pressure roller 33, then enters the first heating device 31 for heating, and then enters between the rear pressure roller 34 and the welding extrusion roller 35. During this period, the weld seam of the steel strip 8 is heated and melted by the second heating device 32, and the welding extrusion roller 35 completes the welding.

[0055] It should be noted that when designing rebound in common molds, only the method of over-deformation to eliminate rebound is considered. However, this is not enough for materials with very high elasticity and cannot be formed. Here we use over-deformation + intermediate extrusion to form deformation of elastic materials + plastic deformation to achieve the elastic material in rolling. Due to the reasons on the rolling production line, it is difficult to achieve plastic deformation because it will cause great resistance. We calculate the pulling force and plastic deformation before and after the mold to ensure that the pulling force is sufficient to maintain the normal operation of the rolling. In addition, the pressure wheel has been improved accordingly, and its structure is as follows Figure 6 shown.

[0056] The shaping unit 4 is fixedly arranged on the other side of the welding unit 3. The shaping unit 4 includes a plurality of rollers arranged in parallel with each other. The stainless steel pipe welded by the welding unit 3 passes through the rollers. The structure of the plurality of rollers arranged in parallel with each other is similar to that of the pressing wheel. Figure 6 The structure shown in FIG. Figure 4 The structure shown.

[0057] The cooling unit 5 is arranged below the welding unit 3 and the shaping unit 4, and is used to cool down the stainless steel pipes that are being welded or that have been welded but not completely shaped. The cooling unit 5 can adopt the method of spray cooling or immersion cooling. This embodiment adopts immersion cooling. The cooling unit 5 is a trough-shaped structure with an open top, which is filled with coolant. Usually, the coolant is an emulsion, and is designed with a circulation device, such as a circulating water pump, to facilitate heat dissipation. The emulsion has the ability to prevent the workpiece from oxidizing during the welding process, while reducing the heat away from the edge of the material, further reducing the generation of oxides, and improving product quality. The full immersion method is used instead of the traditional irrigation method for welding, so that it can be quickly cooled and shaped after welding to prevent rebound welding from being unstable.

[0058] During operation, the steel strip 8 is first sent to the preforming unit 2 through the steel strip conveying unit 1. The preforming unit 2 is deformed by a series of pressing rollers and finally presses the strip 8 into a cylindrical structure, such as Figure 7 shown.

[0059] After the cylindrical steel strip enters the welding unit 3, Figure 5 As shown, it will first be heated by the first heating device 31, which is the preheating step.

[0060] The welded portion of the stainless steel workpiece to be welded is preheated by the first heating device. The preheating process follows a principle similar to that of a conventional high-frequency straight seam welded pipe production line. The first heating device 31 utilizes a high-frequency heating device, thus heating the steel pipe via a high-frequency heating coil. As the steel pipe passes through the heating coil, the high-frequency coil heats the stainless steel workpiece through the skin effect and proximity effect. The skin effect is the property of alternating current flowing through a conductor, where the current is distributed more on the surface than in the center. This high-frequency current flows only along the surface layer, resulting from the magnetic field within the conductor. The strength of the skin effect depends primarily on the frequency of the high-frequency current. The higher the current frequency, the greater the internal inductance of the conductor, and the stronger the skin effect. The proximity effect refers to the property that when two conductors with high-frequency current flowing are closely spaced, the high-frequency current flows only along the adjacent side of the conductors (when the currents in the two conductors are directed in opposite directions) or along the farther side (when the currents in the two conductors are directed in the same direction). The only difference is that the temperature of the first heating device 31 is lower than the melting point of the stainless steel. This means that the preheating temperature is maintained within a temperature range where the welded portion of the stainless steel does not melt and the strength of the base metal is not affected. The purpose of preheating is to pre-elevate the temperature of the stainless steel, facilitating rapid and accurate heating and welding during the subsequent secondary heating. In experiments, this temperature typically does not exceed 1540°C.

[0061] After the preheating step is completed, the preheated stainless steel cylinder continues to enter the second heating device 32 under the push of the steel belt conveyor unit 1.

[0062] The welded portion of the stainless steel part that has been preheated is heated again by a second heating device, so that the welded portion of the stainless steel part is partially melted: the second heating device is a laser heating device. The laser welding method is adopted here mainly because laser welding can quickly increase the temperature of a certain area, and it is also easy to control. This is in line with the requirements of this application for quickly melting the stainless steel oxide layer but not completely melting the stainless steel. The laser beam of the second heating device 32 is irradiated on the edge of the weld of the stainless steel tube. At this time, the area passing through the laser irradiation point will further quickly increase the temperature after preheating, so that the edge of the stainless steel tube on the side of the laser point begins to melt, and its cross section is the same as that in Example 1. Figure 2 Similarly, the melted area is called a molten pool, which has a V-shaped structure. The bottom of the molten pool is the unmelted part, which plays the role of supporting the molten pool and strengthening the connection. Since the welding unit 3 and the shaping unit 4 are both in the cooling unit 5, the coolant in the cooling unit 5 floods the stainless steel cylinder, and the driving effect of the steel belt conveying unit 1 is combined with the adjustment of the laser power, the depth and width of the molten pool can be easily controlled. Figure 2Note: The partial melting depth accounts for between 80% and 95% of the stainless steel part's thickness. To address the issue of weld slag on the inner wall material, high-frequency welding heating is primarily used. High-frequency welding parameters are adjusted to ensure the melting temperature and the affected edge zone. Laser welding is used as a supplement to ensure energy concentration at the weld site, heating the outer material sufficiently to prevent melting of the inner layer. During extrusion, weld slag is turned outward, which is then resolved through subsequent scraping.

[0063] Furthermore, the partial melting depth accounts for 90% of the thickness of the stainless steel part, that is, the melting depth accounts for 90% of the thickness of the stainless steel part, that is, the innermost 10% thickness is not melted. This is the best value obtained in a large number of experiments, which maximizes the mechanical properties of the stainless steel weldment and ensures the cleanliness of its inner wall.

[0064] During the secondary heating process, the stainless steel components are squeezed to fuse the partially melted areas of the weld. While the stainless steel tube is heated by the second heating device 32 to form a V-shaped molten pool, the welding extrusion wheels 35 on either side of the tube squeeze the tube, effectively fusing the molten stainless steel and squeezing out the oxide slag. Because the molten pool is V-shaped, the slag can only drain upward, ensuring a smooth inner wall of the finished tube, eliminating the need for subsequent grinding and polishing.

[0065] Maintain the force of squeezing the stainless steel part and keep it for a while until the welded part of the stainless steel part cools down: After welding, extrusion and fusion are completed, since the stainless steel tube has not completely cooled down and it has a high resilience, it needs to be shaped by the shaping unit 4. The shaping unit 4 includes a plurality of rollers arranged in parallel with each other. The welded stainless steel tube passes through the rollers and is immersed in the coolant of the cooling unit 5, so that cooling and shaping can be achieved quickly. Since the thickness of the stainless steel part is very thin, only 0.1~0.6mm, in order to accelerate heat dissipation and keep the welded part of the stainless steel part only partially melted, it is necessary to add auxiliary cooling means, and the use of coolant can well achieve this purpose. In addition, immersing the stainless steel workpiece in coolant can also reduce contact with air and reduce oxidation.

[0066] The present application discloses an ultra-thin stainless steel combined welding and cooling forming production line, which is optimized and improved on the existing high-frequency straight seam welded pipe production line. The preforming unit 2 is structurally optimized to achieve deformation and shape maintenance of high-elastic stainless steel strips. Then, the welding unit 3 is significantly optimized by adding a first heating device 31 and a second heating device 32. The two heating units cooperate with the welding extrusion wheel 35 to complete the welding of the stainless steel pipe. Then, the shaping unit 4 and the cooling unit 5 are used for cooling and shaping, and finally the welding of the ultra-thin stainless steel pipe is achieved. Using this process, the oxide film on the outer surface of the stainless steel workpiece can be melted, and the side portion of the substrate close to the melted oxide film is also melted. At this time, by squeezing the stainless steel workpiece, the oxide can be squeezed out, and the two sides of the stainless steel workpiece to be welded can be welded and fused. Because the material on the inner wall of the stainless steel workpiece is not melted, it still has sufficient mechanical strength to support the molten pool formed on its upper part without penetrating. Therefore, there is little oxide on its bottom surface, and there is no need to spend a lot of manpower, material resources and time to clean it later, which greatly improves the performance of the welded product.

Claims

1. A method for combining welding and cooling of ultra-thin stainless steel, characterized in that: The steps include: S1. Preheating the welding portion of the stainless steel parts to be welded by a first heating device; S2, secondary heating the preheated welded portion of the stainless steel member by a second heating device, so that the welded portion of the stainless steel member is partially melted; S3. While performing secondary heating, the stainless steel member is extruded so that the partially melted area of the weld is welded and fused; S4. Maintain the force of squeezing the stainless steel part for a period of time until the welded part of the stainless steel part cools down; The thickness of the stainless steel part is 0.1mm~0.6mm; The preheating temperature is maintained within a temperature range where the welded portion of the stainless steel part does not melt and does not affect the strength of its matrix; The secondary heating temperature is equal to or higher than the melting point of the oxide film on the outer surface of the weld; The first heating device is a high-frequency heating device; The second heating device is a laser heating device; The stainless steel piece is subjected to mechanical force and sequentially passes through a first heating device and a second heating device, and is finally extruded and cooled; The partial melting has a melting depth of 80% to 95% of the thickness of the stainless steel part; The cross section of the partially melted stainless steel piece is in a V-shaped structure.

2. The ultra-thin stainless steel combined welding and cooling forming method according to claim 1, characterized in that: During the execution of steps S1 to S4, the stainless steel parts are immersed in the coolant.

3. The ultra-thin stainless steel combined welding and cooling forming method according to claim 2, characterized in that: The cooling liquid is an emulsion.

4. The ultra-thin stainless steel combined welding and cooling forming method according to claim 1, characterized in that: Before step S1, a stainless steel part pre-deformation step is also included, in which the stainless steel part can be bent into a desired shape using a pressing roller or a roller.

Images