Method for welding a sheet metal

Abstract

This invention belongs to the field of welding technology and discloses a welding method for plates. First, two base plates are processed and positioned to form a weld between them. Then, the entire weld is horizontally welded, forming a root pass and a filler pass sequentially at the weld. A cover pass is then horizontally welded onto the filler pass. Finally, multiple passes are used for the horizontal welding of the cover pass. In the last pass of the cover pass, a DC reverse polarity right-hand welding method is employed. The welding machine's arc-extinguishing switch is set to no arc extinguishing, and the welding torch is manually controlled. Welding is performed using intermittent arc-feeding wire feeding. This method overcomes the technical challenge of undercut at the horizontal welding position, reduces damage and impact on the base plate caused by post-weld grinding, and improves welding quality.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more particularly to a method for welding plates. Background Technology

[0002] Semi-automatic flux-cored wire CO2 gas shielded welding (FCAW) is widely used in shipbuilding and other industries, with horizontal welding being the most common position. Undercut at the weld bead edge is a very common phenomenon. When welding the capping layer horizontally, multiple passes are required. In the final pass of the capping layer, the commonly used continuous arc welding method is employed. Due to the downward force of the molten iron pool and unstable operator movements, the sharp edges of the upper bevel are easily melted, and the welding wire cannot fill the molten crater in time, resulting in undercut of varying depths from 0.3 to 1 mm. Undercut is a major cause of stress concentration. Currently, the main measure is to grind the weld toe where undercut occurs to eliminate it. However, grinding reduces the effective cross-sectional area of ​​the weld and the effective thickness of the base metal. Especially in the welding of thin plates for large cruise ships, excessive grinding can cause irreversible damage to the base metal.

[0003] Therefore, there is an urgent need for a welding method for sheet metal to solve the problems in the existing technology. Summary of the Invention

[0004] The purpose of this invention is to provide a welding method for plates that can eliminate undercut during the final welding of the horizontal weld cover layer and improve welding quality.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] Welding methods for sheet metal include:

[0007] S100. Process and position the two mother plates to form a weld between them;

[0008] S200. Perform horizontal welding on the entire weld seam, and sequentially form a root layer and a filler layer at the weld seam, and then horizontally weld a cover layer on the filler layer.

[0009] S300. When welding the cover layer horizontally, multiple welding passes are used. When welding the last pass of the cover layer, the DC reverse polarity right welding method is used. The arc-extinguishing switch function of the welding machine is set to no arc extinguishing. The welding gun switch is manually controlled, and the arc-breaking point wire feeding is used for welding.

[0010] Optionally, during the final welding of the cover layer, the following are also included: S310, the frequency of supplying the arc-breaking point-feeding welding wire is 2 times / s.

[0011] Optionally, the final weld of the cover layer may also include:

[0012] S320. Select an appropriate welding current and match an appropriate arc voltage according to the material and thickness of the mother plate;

[0013] S330, The welding current is 180A-230A, and the matching arc voltage is 23V-26V.

[0014] Optionally, the final weld of the cover layer may also include:

[0015] S340. During the movement of the welding torch, the angle of the welding torch must always be tilted to the right by 20°-30°.

[0016] Optionally, the final weld of the cover layer may also include:

[0017] S350 uses flux-cored wire CO2 gas shielded welding. The wire is always kept in the center of the weld bead, and attention is paid to the fusion of the bevel edges and corners.

[0018] Optionally, the final weld of the cover layer may also include:

[0019] S360, maintain a suitable and stable welding speed;

[0020] S370, the welding speed is maintained at 75mm / min-130mm / min.

[0021] Optionally, the processing and positioning of the two mother plates includes:

[0022] S110. Select two mother plates to be welded, and cut a V-shaped bevel at one end of the mother plates;

[0023] S120, Connect the V-shaped bevels of the two mother plates and leave a root gap;

[0024] S130. Install arc-extinguishing plates at the ends of the two mother plates and perform tack welding.

[0025] Optionally, when performing horizontal welding on the entire weld seam, the following may also be included:

[0026] S210. The entire weld seam between the two mother plates is horizontally welded using flux-cored wire CO2 gas shielded welding to form the root layer and the filler layer.

[0027] Beneficial effects:

[0028] The welding method for plates provided by this invention first processes and positions two mother plates to form a weld between them; then, the entire weld is horizontally welded, forming a root pass and a filler pass sequentially at the weld, and a cover pass is horizontally welded on the filler pass; finally, multiple passes are used when horizontally welding the cover pass, and a DC reverse polarity right-hand welding method is used for the last pass of the cover pass. The arc-extinguishing switch function of the welding machine is set to no arc extinguishing, the welding gun is manually controlled, and arc-breaking point wire feeding is used for welding. This method can overcome the technical problem of undercut at the horizontal welding position, reduce the damage and impact on the mother plate (especially thin plates) caused by post-weld grinding, and improve the welding quality. Attached Figure Description

[0029] Figure 1 This is a flowchart of the welding method for the plate material provided by the present invention;

[0030] Figure 2 This is a schematic diagram of the structure when welding two mother plates using the welding method for the sheet metal provided by this invention.

[0031] In the picture:

[0032] 10. Mother plate; A. Last layer of cover coat. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0037] When welding the cover layer horizontally, only multiple welding passes can be used. During the last welding pass of the cover layer, due to the gravity of the molten iron in the pool falling and the instability of the operator's hand gestures, undercut often occurs at the upper edge of the weld, resulting in welding defects and a decrease in weld strength.

[0038] To solve this problem, such as Figures 1-2 As shown, this embodiment provides a welding method for sheet metal, designed to effectively eliminate undercut during the final pass of the horizontal weld overlay, thereby improving weld quality and weld strength. Specifically, the welding method for sheet metal includes:

[0039] S100. Select two mother plates 10, process and position the two mother plates 10 to form a weld between the two mother plates 10;

[0040] S200. Perform horizontal welding on the entire weld seam, forming a root pass and a filler pass sequentially at the weld seam, followed by a horizontal cap pass on the filler pass. Welding the root pass and filler pass first allows the welding wire to better integrate into the weld seam, forming a stable molten pool, which helps avoid voids, porosity, and other welding defects that may occur in the weld seam. Welding layer by layer slows down the rate of heat transfer, preventing overheating of the molten pool, thereby reducing the risk of stress concentration and thermal deformation, and ensuring the quality, strength, and stability of the weld seam.

[0041] S300, When welding the cover layer horizontally, multiple welding passes are used, and during the last welding pass of the cover layer ( Figure 2(At position A in the diagram), the DC reverse polarity right-hand welding method is used. The welding machine's arc-extinguishing switch function is set to no arc extinguishing, and the welding torch is manually controlled. Welding is performed using intermittent arc-feeding. By employing the DC reverse polarity right-hand welding method, the direction of welding current flow can be changed, enhancing the control of welding heat and thus improving welding stability. Intermittent arc-feeding allows for more precise control of the welding wire supply during welding, ensuring uniform molten pool formation and reducing undercut. Manual control of the welding torch, along with the use of multi-pass welding and intermittent arc-feeding technology, improves the flexibility and accuracy of welding operations, thereby enhancing welding quality and weld strength.

[0042] The welding method for this plate overcomes the technical challenge of undercut at the horizontal welding position, reduces the damage and impact on the mother plate 10 (especially thin plates) caused by post-weld grinding, and improves welding quality. It should be noted that the thin plates mentioned in this embodiment generally refer to plates with a thickness of less than 10mm. Using the welding method provided in this embodiment, undercut is eliminated during the horizontal welding of thin plates in large cruise ships, avoiding irreversible damage caused by excessive grinding, thereby significantly improving welding quality.

[0043] Optionally, during the final weld of the capping layer, the method also includes: S310, a wire feeding frequency of 2 times / s using intermittent arc-feeding. Intermittent arc-feeding briefly interrupts the wire feeding cycle, allowing the molten pool to cool appropriately during the feeding intervals. This helps to more precisely control the input of welding heat, thereby effectively controlling the formation and size of the weld pool and improving the quality, consistency, and strength of the weld. Therefore, an appropriate intermittent arc-feeding frequency can prevent undercut at the weld bevel, and a feeding frequency of 2 times / s helps the wire fill the weld more evenly, reducing the sharp angle of the upper bevel edge and thus lowering the likelihood of undercut.

[0044] Optionally, the final weld of the cover layer may also include:

[0045] S320. Select an appropriate welding current and match an appropriate arc voltage according to the material and thickness of the mother plate 10.

[0046] S330, welding current is 180A-230A, and the matching arc voltage is 23V-26V.

[0047] By selecting an appropriate welding current based on the material and thickness of the base plate 10, it is possible to ensure that the welding heat is just right, avoiding excessive or insufficient heat input. Matching an appropriate arc voltage can further adjust the control of the welding heat source, reducing thermal deformation of the base material during welding and improving the stability and consistency of the weld.

[0048] Optionally, during the final welding of the cover layer, the following steps are also included: S340, the welding torch angle must always be maintained at 20°-30° to the right during the welding torch movement. By controlling the welding torch angle, the shape and size of the weld can be better controlled, making the welding process more precise and stable. Maintaining the welding torch angle to the right makes it easier for the welder to control the welding speed during the welding movement, helping to ensure that the welding wire fully fills the weld and avoiding the welding wire moving too early or too late, thereby improving the welding quality.

[0049] Optionally, the final weld of the capping layer also includes: S350, using flux-cored wire CO2 gas shielded welding, keeping the wire centered in the weld bead at all times, and focusing on the fusion of the bevel edges. By keeping the wire centered in the weld bead, it is ensured that the wire fills the weld evenly during the welding process, forming a uniform molten pool and improving weld quality. Focusing on the fusion of the bevel edges helps ensure sufficient fusion at the weld top and reduces the occurrence of undercut.

[0050] Optionally, the final weld of the cover layer may also include:

[0051] S360, maintain a suitable and stable welding speed;

[0052] S370, welding speed should be maintained between 75mm / min and 130mm / min.

[0053] Maintaining the welding speed within the range of 75 mm / min to 130 mm / min can achieve better welding quality, welding speed, and weld stability. However, welders need to make appropriate adjustments and controls based on specific welding conditions and experience to ensure that the selected welding speed achieves the expected results in practical applications.

[0054] Optionally, the processing and positioning of the two mother plates 10 includes:

[0055] S110. Select two mother plates 10 to be welded, and make a V-shaped bevel at one end of the mother plate 10.

[0056] S120, V-shaped bevels of two mother plates 10, with a reserved root gap;

[0057] S130. Install the arc-extinguishing plates at the ends of the two mother plates 10 and perform tack welding.

[0058] The above steps provide a suitable foundation for the welding process, ensuring that the mother plate 10 can be correctly positioned during welding, the weld can be fully filled, and the arc-extinguishing plate can work stably, thereby improving the welding quality and weld strength.

[0059] Optionally, when performing horizontal welding on the entire weld seam, the following may also be included:

[0060] S210. A flux-cored wire CO2 gas shielded welding technique is used to horizontally weld the entire weld seam between the two mother plates 10, forming the root pass and filler layer. By using flux-cored wire CO2 gas shielded welding to horizontally weld the entire weld seam, forming the root pass and filler layer, welding quality, weld strength, and welding efficiency can be improved.

[0061] Specifically, such as Figures 1-2 As shown, the detailed steps of the welding method for the plate provided in this embodiment are as follows:

[0062] S100. Process and position the two mother plates 10 to form a weld between the two mother plates 10;

[0063] S110. Select two mother plates 10 to be welded, and make a V-shaped bevel at one end of the mother plate 10.

[0064] S120, V-shaped bevels of two mother plates 10, with a reserved root gap;

[0065] S130. Install the arc-extinguishing plates at the ends of the two mother plates 10 and perform tack welding.

[0066] S200. Perform horizontal welding on the entire weld seam, forming a root layer and a filler layer in sequence at the weld seam, and then horizontally welding a cover layer on the filler layer.

[0067] S210, CO2 gas shielded welding with flux-cored wire is used to horizontally weld the entire weld seam between the two mother plates 10 to form the root layer and the filler layer.

[0068] S300. When welding the cover layer horizontally, multiple welding passes are used. When welding the last pass of the cover layer, the DC reverse polarity right welding method is used. The arc-extinguishing switch function of the welding machine is set to no arc extinguishing. The welding gun switch is manually controlled, and the arc-breaking point wire feeding is used for welding.

[0069] S310, the frequency of supplying the arc-breaking point-feeding welding wire is 2 times / s.

[0070] S320. Select an appropriate welding current and match an appropriate arc voltage according to the material and thickness of the mother plate 10.

[0071] S330, welding current is 180A-230A, and the matching arc voltage is 23V-26V.

[0072] S340. During the movement of the welding torch, the angle of the welding torch must always be tilted to the right by 20°-30°.

[0073] S350 uses flux-cored wire CO2 gas shielded welding. The wire is always kept in the center of the weld bead, and attention is paid to the fusion of the bevel edges and corners.

[0074] S360, maintain a suitable and stable welding speed;

[0075] S370, welding speed should be maintained between 75mm / min and 130mm / min.

[0076] By adopting the above-mentioned welding method for the plates, the technical problem of undercut at the horizontal welding position can be overcome, the damage and impact on the mother plate 10 (especially thin plates) caused by post-weld grinding can be reduced, and the welding quality can be improved.

[0077] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A welding method for plates, characterized in that, include: S100. Process and position the two mother plates (10) to form a weld between the two mother plates (10); S200. Perform horizontal welding on the entire weld seam, and sequentially form a root layer and a filler layer at the weld seam, and then horizontally weld a cover layer on the filler layer. S300. When welding the cover layer horizontally, multiple welding passes are used. When welding the last pass of the cover layer, the DC reverse polarity right welding method is used. The arc-extinguishing switch function of the welding machine is set to no arc extinguishing. The welding gun switch is manually controlled, and the arc-breaking point wire feeding is used for welding. During the final welding of the cover layer, the following are also included: S310, the frequency of supplying the arc-breaking point-feeding welding wire is 2 times / s; The final welding of the cover layer also includes: S340. During the movement of the welding torch, the angle of the welding torch must always be tilted to the right by 20°-30°. S350, using flux-cored wire CO2 gas shielded welding, the wire is always kept in the center of the weld bead, and attention is paid to the fusion of the bevel edges and corners; S360, maintain a suitable and stable welding speed; S370, the welding speed is maintained at 75mm / min-130mm / min.

2. The welding method for plates according to claim 1, characterized in that, The final welding of the cover layer also includes: S320. Select a suitable welding current and match a suitable arc voltage according to the material and thickness of the mother plate (10); S330, The welding current is 180A-230A, and the matching arc voltage is 23V-26V.

3. The welding method for plates according to claim 1, characterized in that, The processing and positioning of the two mother plates (10) includes: S110. Select two mother plates (10) to be welded, and make a V-shaped bevel at one end of the mother plate (10); S120, the V-shaped bevel of the two mother plates (10) are connected, and a root gap is reserved; S130. Install the arc-extinguishing plates at the ends of the two mother plates (10) and perform tack welding.

4. The welding method for plates according to claim 1, characterized in that, When performing horizontal welding on the entire weld seam, it also includes: S210. The entire weld seam between the two mother plates (10) is horizontally welded using flux-cored wire CO2 gas shielded welding to form the root layer and the filler layer.

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