A welding method for the transverse welding of a PCTC ship plate

Abstract

This invention provides a welding method for horizontal welding of PCTC ship thin plates, including the following steps: Step 1: A dedicated horizontal EGW welding equipment hardware is used, employing both vertical and horizontal oscillators to achieve triangular oscillation. The control box allows for independent adjustment of the current and voltage at the front and rear. Step 2: Optimization and improvement of the water-cooled slider groove form, assembly bevel form, bevel angle, and bevel gap. This invention utilizes a single-sided welding double-sided one-time forming gas slag shielded welding technology for horizontal butt welding of PCTC ship thin plates, employing different welding currents and voltages applied to the same molten pool at the root and face of the triangular oscillation. Improvements were made to the gas slag shielded welding slider groove form, assembly bevel form, bevel angle, and gap. Welding processes and operating methods were established, including wire distance, triangular oscillation width, dwell time, and different welding parameters for the root and face of the gas slag shielded welding, to achieve mechanized and automated welding of the horizontal butt joint position using single-sided welding double-sided one-time forming gas slag shielded welding.

Description

Technical Field

[0001] This invention belongs to the field of ship welding technology, and specifically relates to a welding method for horizontal welding of thin plates in PCTC ships. Background Technology

[0002] The hull plating of a typical ship is 12mm to 25mm thick. The transverse seam is a major component of hull welding. For many years, domestic shipyards have mainly used CO2 semi-automatic welding or oscillating trolley welding methods for transverse butt welds of the hull.

[0003] For PCTC vessels, the 7.5mm-10.5mm thick hull plating assembly uses a method of CO2 semi-automatic welding for the root pass and multi-layer, multi-pass filler welds, followed by multi-pass cover welding using a trolley. This existing technology has the following problems:

[0004] 1. Since the outer panel is welded horizontally using CO2 semi-automatic welding + oscillating welding carriage, the horizontal butt weld is prone to defects such as curling, slag inclusion and lack of fusion due to the influence of the welding position and the skill level of the welder. It is difficult to guarantee the welding quality and efficiency.

[0005] 2. Due to the large workload and low efficiency of multi-layer and multi-pass welding, the horizontal butt welds tend to have a greater tendency to angular deformation. The addition of post-weld heat treatment procedures further complicates the construction efficiency. Summary of the Invention

[0006] This invention provides a welding method for horizontal welding of PCTC ship thin plates, comprising the following steps:

[0007] Step 1: The horizontal dedicated EGW welding equipment hardware uses a dual swing mechanism (up and down and front and back) to achieve triangular swing. The control box allows for independent adjustment of the front and rear current and voltage.

[0008] Step 2: Optimize and improve the groove form, assembly bevel form, bevel angle, and bevel gap of the water-cooled slider;

[0009] Step 3: Develop welding processes, materials, and operating methods for gas slag shielded welding, including wire spacing, triangular oscillation width, dwell time, welding torch position, welding torch angle, root and face welding parameters, and welding backing.

[0010] Step 4: Achieve mechanized and automated welding of single-sided welding with double-sided one-time forming and gas slag protection in the horizontal butt joint position, and compare the angular deformation with CO2 welding multi-pass multi-layer welding;

[0011] Step 5: Post-weld treatment. If undercut or incomplete welding occurs on the upper bevel after welding, it must be repaired with carbon dioxide gas shielded welding.

[0012] Preferably, the hardware of the transverse dedicated EGW welding equipment includes:

[0013] Welding machine, wire feeder, water tank, welding wire, main body of horizontal special welding trolley equipment and control box;

[0014] The main body of the transverse special welding trolley equipment includes an up-and-down swing mechanism and a front-and-back swing mechanism;

[0015] The welding machine includes a conductive nozzle.

[0016] Preferably, the water-cooled slider includes a base plate and a bent vertical plate. The bent vertical plate is installed on one end of the upper wall of the base plate, and the angle between the bent vertical plate and the wall of one end of the base plate is 50°. A semi-eyeglass-shaped groove is formed on the lower wall of the base plate.

[0017] Preferably, the bevel form is a single-sided V-shaped bevel, and the bevel angle is 45° at the top and 0° to 2° at the bottom.

[0018] Preferably, the bevel gap is 4 to 8 mm.

[0019] Preferably, the length of the welding wire is 30-35 mm.

[0020] Preferably, the triangular swing width is: 5-6 mm for the forward and backward swing of the welding torch triangular swing shape, and 4-8 mm for the vertical swing width of the welding torch triangular swing shape face.

[0021] Preferably, the dwell time is as follows: the dwell time at the root of the welding torch in the triangular swing pattern is 0.5 sec, the dwell time at the top of the surface is 0.8 sec, the dwell time at the bottom of the surface is 1.1 sec, and the swing speed is 14 mm / sec.

[0022] Preferably, the welding torch position includes: when the welding torch is not welding in the triangular swing state, the position of the welding torch in the stopped state is at the root position in the triangular swing state, the distance between the root position and the lower bevel of the horizontal butt joint is 3-4 mm, and the distance between the root position and the root of the bevel is 1-2 mm.

[0023] Preferably, the welding torch angle includes: when welding materials with a thickness of 7.5mm to 10.5mm, the welding torch forms an angle of 3° to 4° with the plate surface.

[0024] Preferably, the conductive tip is made of chromium zirconium copper material, the conductive tip has a specification size of Φ1.42*M6*45mm, and the conductive tip has an outer diameter of M6*3.4mm.

[0025] The beneficial effects of this invention are as follows: By developing a single-sided welding double-sided one-time forming gas slag shielded welding technology for PCTC ship thin plate transverse butt welding, which utilizes a triangular oscillation mechanism with different welding currents and voltages applied to the same molten pool at the root and face, the invention improves the form of the gas slag shielded welding slider groove, the assembly bevel form, the bevel angle, and the gap. It also establishes welding processes and operating methods for gas slag shielded welding, including wire distance, triangular oscillation width, dwell time, and different welding parameters for the root and face. This achieves mechanized and automated welding of single-sided welding double-sided one-time forming gas slag shielded transverse butt joints, eliminating the cumbersome process of multiple layers of welding. The invention employs both vertical and horizontal oscillators to achieve triangular oscillation, allowing the root and face to penetrate the weld with different welding currents and voltages at smaller welding parameters. The water-cooled slider on the front side blocks the molten metal while rapidly reducing its temperature, forcing it to form in one step within the weld and obtaining a uniform and fine microstructure, reducing angular deformation, improving work quality, and increasing work efficiency.

[0026] As can be seen from the above scheme, the embodiments of the present invention provide a welding method for horizontal welding of PCTC ship thin plates. Attached Figure Description

[0027] Figure 1 A flowchart illustrating the steps of a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention;

[0028] Figure 2 A front view of the dedicated EGW welding equipment hardware for transverse welding of PCTC ship thin plates according to an embodiment of the present invention.

[0029] Figure 3 A three-dimensional view of a water-cooled slider illustrating a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention;

[0030] Figure 4 A side sectional view of a water-cooled slider illustrating a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention.

[0031] Figure 5 A three-dimensional view of a conductive nozzle illustrating a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention.

[0032] Figure 6 A welding schematic diagram illustrating a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention;

[0033] Figure 7 A schematic diagram showing the root position of the welding torch in a triangular swing configuration, illustrating a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention.

[0034] Figure 8A schematic diagram showing the lower position of the triangular oscillating surface of the welding torch in a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention.

[0035] Figure 9 A schematic diagram showing the upper position of the triangular oscillating surface of the welding torch in a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention.

[0036] Figure 10 A schematic diagram of the weld seam illustrating a welding method for horizontal welding of PCTC ship thin plates according to an embodiment of the present invention;

[0037] In the diagram, 1 is the up-and-down swing mechanism; 2 is the forward-and-backward swing mechanism; 3 is the control box; 4 is the conductive nozzle; 5 is the water-cooled slider; 501 is the base plate; 502 is the bent vertical plate; 503 is the semi-spectacle-shaped groove; and 6 is the welding gasket. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0039] A welding method for horizontal welding of PCTC ship thin plates includes the following steps:

[0040] Step 1: The horizontal dedicated EGW welding equipment hardware uses a dual swing mechanism (up and down and front and back) to achieve triangular swing. The operation box 3 allows for independent adjustment of the front and rear current and voltage.

[0041] Step 2: Optimize and improve the groove form, assembly bevel form, bevel angle, and bevel gap of the water-cooled slider 5;

[0042] Step 3: Develop welding processes, materials, and operating methods for gas slag shielded welding, including wire spacing, triangular oscillation width, dwell time, welding torch position, welding torch angle, root and face welding parameters, and welding backing 6.

[0043] Step 4: Achieve mechanized and automated welding of single-sided welding with double-sided one-time forming and gas slag protection in the horizontal butt joint position, and compare the angular deformation with CO2 welding multi-pass multi-layer welding;

[0044] Step 5: Post-weld treatment. If undercut or incomplete welding occurs on the upper bevel after welding, it must be repaired with carbon dioxide gas shielded welding.

[0045] 1. Equipment hardware and pre-welding preparation:

[0046] In the specific implementation process, the hardware of the horizontal dedicated EGW welding equipment further includes: welding machine, wire feeder, water tank, welding wire, the main body of the horizontal dedicated welding trolley equipment and operation box 3;

[0047] The main body of the transverse special welding trolley equipment includes an up-and-down swinger 1 and a front-and-back swinger 2; the up-and-down swinger 1 and the front-and-back swinger 2 work together to achieve triangular swing and perform automatic welding.

[0048] Control box 3 is the driving control and operation panel for the operating equipment, and the welding parameters, such as the face and root current and voltage, can be adjusted separately;

[0049] The welding machine includes a conductive nozzle 4; the conductive nozzle 4 is made of chromium zirconium copper material, and its specifications are Φ1.42*M6*45mm. In order to facilitate the triangular swing of the thin plate for horizontal butt welding, the conductive nozzle 4 has a pointed conical shape of M6*3.4mm.

[0050] In the specific implementation process, the water-cooled slider 5 further includes a base plate 501 and a bent vertical plate 502. The bent vertical plate 502 is installed on one end of the upper wall of the base plate 501, and the angle between the bent vertical plate 502 and one end of the wall of the base plate 501 is 50°. A semi-glasses-shaped groove 503 is opened on the lower wall of the base plate 501.

[0051] More specifically, to ensure forced forming of the front side of the horizontal butt weld, the cross-sectional shape of the groove on the lower wall of the bottom plate 501 in the water-cooled slider 5 is designed as a semi-mirror-shaped groove 503, which is conducive to the forming of the horizontal butt weld and the removal of welding slag. In order to better observe the molten pool when welding the horizontal butt weld, the water-cooled slider 5 is designed with the angle between the bent vertical plate 502 and one end wall of the bottom plate 501 at 50° in the length direction. The length of the water-cooled slider 5 is 100mm, the length of the beveled end is 75mm, the width is 55mm, the thickness is 18mm, the width of the semi-mirror-shaped groove 503 is 20mm, the depth of the plane part of the semi-mirror-shaped groove 503 is 2mm, the semi-circular diameter of both ends of the semi-mirror-shaped groove 503 is 4mm, and the depth of the semi-circular arc part of the semi-mirror-shaped groove 503 is 3mm.

[0052] In the specific implementation process, the bevel form is further as follows: a single-sided V-shaped bevel with a bevel angle of 45° at the top and 0° to 2° at the bottom.

[0053] More specifically, in order to achieve single-sided welding and double-sided forming of horizontal butt joints, the bevel is designed as a single-sided V-shaped bevel with a bevel angle of 45° at the top and 0° to -2° at the bottom. The larger upper bevel angle is beneficial for observing the molten pool by the angle of the welding torch and the triangular swing, while the straight lower bevel is beneficial for supporting the molten pool when the welding torch swings, thus preventing slag inclusions at the lower end of the weld.

[0054] In practice, the bevel gap is further reduced to 4–8 mm.

[0055] More specifically, the gap between the bevel assembly should be controlled between 4 and 8 mm, with a maximum value not exceeding 10 mm. Within 50 mm on both sides of the bevel edge, use a grinding wheel to remove burrs, jagged edges, metal spatter, and remove moisture, rust, oil, etc., to ensure that the water-cooled slider 5 on the front of the bevel slides smoothly and the gasket on the back of the bevel is tightly attached.

[0056] It should also be noted that:

[0057] During welding, ceramic welding gasket 6 is used for one-time forming of the back side of the horizontal butt weld, ensuring the height and width of the weld seam on the back side of the thin plate. The appearance dimensions of the ceramic gasket, such as the arc-shaped groove, are designed as follows: width 40mm, thickness 10mm, groove width 15mm, arc depth radius 2mm. The bottom of the ceramic groove is surrounded and fixed with 1mm iron sheet. The ceramic welding gasket 6 has the following technical properties: sulfur <0.05%, phosphorus <0.1%, moisture absorption ≤0.4%, bulk density ≥1.75g / cm3, flexural strength ≥83g / cm2, 180° peel force ≥20N / 2.5cm, and refractoriness 1300℃.

[0058] The steel plates used for the outer side plating of the PCTC ship are high-strength E-grade hull structural steel. To ensure the quality of the gas slag shielded horizontal welding, 3Y-grade flux-cored welding wire must be used, with a grade and specification of SC-EGH, Φ1.4mm. The composition of the flux-cored welding wire must meet the following requirements: carbon ≤0.05%, sulfur <0.004%, phosphorus <0.007%, silicon ≤0.90%, manganese ≤2.0%, copper ≤0.35%, nickel ≤0.30%, molybdenum ≤0.35%, vanadium ≤0.08%.

[0059] The steel plates used for the outer side plating of the PCTC ship are Class E high-strength hull structural steel, and the CO2 gas used should have a purity of not less than 99.8%.

[0060] 2. Welding process parameter design:

[0061] In practice, the welding wire length is further specified as 30-35mm.

[0062] More specifically, the wire extension length for gas slag shielded welding is 30-35mm. If the wire extension length is too long, the resistance heat increases, the melting speed is fast, and it is easy to overheat and burn out, resulting in severe spatter and poor shielding effect, affecting the stability of the welding process and causing poor weld formation. If the wire extension length is too short, it is easy to cause blockage of the shielding gas outlet of the slider, resulting in poor shielding and affecting the welding quality.

[0063] In the specific implementation process, the triangular swing width is further defined as follows: the forward and backward swing width of the welding torch triangular swing shape is 5-6 mm, and the vertical swing width of the welding torch triangular swing shape is 4-8 mm.

[0064] More specifically, in gas slag shielded welding, the welding torch can swing vertically (Y) and back and forth (X) using the up-and-down swinging device 1 and the back-and-forth swinging device 2. By using the back-and-forth and up-and-down swinging, a triangular swing is achieved. The triangular swing is formed by the simultaneous coordination of the XY swinging devices. The triangular swinging is more conducive to the removal of weld slag and the fullness of the weld face when the thin plate is butt welded. By using different welding current and voltage at the root and face of the weld through the triangular swinging, the fullness of the weld face can be achieved with smaller welding parameters. It can also reduce welding parameters and obtain a uniform and fine structure.

[0065] According to the PCTC ship side outer plate transverse butt joint of 7.5mm to 10.5mm, the triangular swing is formed by the simultaneous coordination of XY swingers. The forward and backward swing width of the welding torch in the triangular state is 5 to 6mm, and the vertical swing width of the face is 4 to 8mm, which is the swing width of the triangular state of the bevel gap size.

[0066] In the specific implementation process, the dwell time is further specified as follows: the dwell time at the root of the welding torch in the triangular swing pattern is 0.5 seconds, the dwell time at the top of the surface is 0.8 seconds, and the dwell time at the bottom of the surface is 1.1 seconds, with a swing speed of 14 mm / sec.

[0067] More specifically, to ensure the fullness and penetration of the weld on both sides, the diagonal rotation speed in the triangular oscillation is determined by the real-time calculated oscillation amplitude and oscillation speed.

[0068] In the specific implementation process, the welding gun position further includes: when the welding gun is not welding in the triangular swing, the position of the welding gun in the stopped state is at the root position in the triangular swing, the distance between the root position and the lower bevel of the horizontal butt joint is 3-4mm, and the distance between the root position and the root of the bevel is 1-2mm.

[0069] In specific implementation, the welding torch angle further includes: when welding materials with a thickness of 7.5mm to 10.5mm, the welding torch should form an angle of 3° to 4° with the plate surface.

[0070] Welding parameter design: The welding wire is melted by the energy of different arcs at the root and face in a triangular oscillation. The resulting liquid metal fills the weld seam in a triangular oscillation. The welding parameters can be reduced by the triangular oscillation. The front water-cooled slider 5 and the back ceramic welding pad 6 block the molten metal and can also quickly reduce the temperature of the molten metal, so that it is forced to form in one step in the weld seam and obtain a uniform and fine structure. The welding parameters are shown in the table below.

[0071]

[0072] Note: The flux-cored welding wire used is grade SC-EGH, Φ1.4mm.

[0073] Water-cooled slider selection: The size of the semi-mirror-shaped groove 503 of the water-cooled slider 5 can be selected based on the width of the bevel face plus about 2mm. For example, for a plate thickness of 10mm, a horizontal butt joint with an upper bevel of 45°, a lower bevel of 0°, and a gap of 8mm, the width of the bevel face is 18mm, and the size of the semi-mirror-shaped groove 503 of the water-cooled slider 5 is selected to be 20mm. The semi-mirror-shaped groove 503 is selected to be semi-mirror-shaped. The triangular swing can make better use of the semicircles at both ends of the semi-mirror-shaped groove 503 to make the weld seam of the upper and lower bevel edges of the horizontal butt joint full.

[0074] 3. Specific steps for welding operation:

[0075] ①After the PCTC ship's side outer plating is assembled transversely, install a transverse EGW welding trolley, install the ceramic welding gasket 6 tightly against the back of the bevel, connect the welding equipment to water, electricity, and gas, and confirm that the water pressure is 1.2L / min (5Kg / cm2) and the gas flow rate meets the usage requirements.

[0076] ② Adjust the welding torch position and angle, and set the oscillator: Set the specific values ​​according to the welding process parameters. The oscillator always stops at the root (ROOT) and starts from this R point, then reverses and repeats the cycle. In the triangular oscillation, the speed in the diagonal direction is proportional to the speed of the forward and backward oscillation, which determines the descent speed of the up and down oscillation. The diagonal rotation speed in the triangular oscillation is determined by the real-time calculated oscillation amplitude and oscillation speed.

[0077] ③ Start welding. Press the “Start” button to intermittently ignite the electric arc with small parameters. After the molten pool is established, start welding according to the parameters in the welding parameter range table above, and adjust the centering of the welding torch and the clamping of the water-cooled slider 5.

[0078] ④ After the welding pool is established, the weld pool should be kept 2-5 mm below the lower end face of the air outlet of the water-cooled slider 5 while the electric arc is burning normally;

[0079] ⑤ During the welding process, observe the wire alignment and heat distribution of the weld according to the actual bevel and gap at any time, adjust the welding parameters and triangular oscillation at any time, and adjust the different arc pools at the root and face to the correct position at any time through mechanical devices. At the same time, use an insulating rod to remove the spatter in the protective gas box of the water-cooled slider 5 at any time.

[0080] ⑥ After welding is finished, press the "Stop" button to extinguish the arc. After the molten pool solidifies, release the water-cooled slider 5 and remove the spatter. Remove the welding torch from the support.

[0081] ⑦ After welding is completed, turn off the power, gas, and water supply, put away the welding wire and hose coils, and park the parts in a suitable place.

[0082] 4. Comparison of welding deformation between gas slag shielded welding and CO2 semi-automatic welding:

[0083] During the assembly and loading phase of the PCTC ship's side outer plating transverse butt welds, a V-shaped external bevel was used. CO2 semi-automatic welding mainly resulted in angular deformation, which was primarily related to the welding heat input and the number of welding passes. Through comparative experiments, the angular deformation of mechanized and automated welding of the transverse butt joints with single-sided welding, double-sided one-time forming, and slag protection was significantly reduced compared to CO2 semi-automatic welding.

[0084] ① Welding heat input: q=I*U*60 / V (i.e.: current*voltage*60 / speed), J / cm;

[0085] CO2 semi-automatic welding parameters: current 210~270A, voltage 24~30V, speed 65~430mm;

[0086] Gas slag shielded horizontal welding parameters: current 250~285A, voltage 29~31V, speed 107~125mm;

[0087] The angular deformation results of the unconstrained 10mm thick * 1000 * 600mm test plate with the above welding parameters are as follows:

[0088] A. For horizontal welding with gas slag shielding, q = I * U * 60 / V, the angular deformation and depression is 1.65 cm.

[0089] B. CO2 semi-automatic welding q=(I1*U1*60 / V1)+(I2*U2*60 / V2)+(I3*U3*60 / V3)+(I4*U4*60 / V4)+(I5*U5*60 / V52) Angular deformation depression is 2.94cm

[0090] a. The deformation and depression of the root pass weld in CO2 semi-automatic welding is 1.03cm.

[0091] b. The deformation and depression of the first fillet weld in CO2 semi-automatic welding is 0.47cm.

[0092] c. The deformation and depression of the second fillet weld in CO2 semi-automatic welding is 0.69cm.

[0093] The deformation and depression of the first weld bead on the CO2 semi-automatic weld cover surface was 0.36 cm.

[0094] The deformation and depression of the first weld bead on the e.CO2 semi-automatic weld cover surface is 0.43cm.

[0095] ② Through experimental welding, double-sided one-time forming of gas slag protection reduced the deformation of the cross joint corner by 1.65cm by nearly 2 times.

[0096] 5. Inspection after gas-slag protected horizontal butt weld:

[0097] ① After welding, any undercut or incomplete weld at the upper end of the bevel should be repaired using carbon dioxide gas shielded welding.

[0098] ② Welding inspection, examination and performance testing were carried out in accordance with the classification society's "Welding and Materials". The weld was visually inspected and found to be well formed on both sides with no welding defects (see figure below). The appearance inspection was qualified. After 24 hours of welding, 100% UT + 10% RT non-destructive testing was carried out and the results were qualified.

[0099] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A welding method for horizontal welding of PCTC ship thin plates, characterized in that, The following steps are included: Step 1: The horizontal dedicated EGW welding equipment hardware uses an up-and-down swing device (1) and a front-and-back swing device (2) to realize the triangular swing of the welding torch. The control box can adjust the current and voltage of the weld face and root separately. Step 2: Optimize and improve the groove form, assembly bevel form, bevel angle and bevel gap of the water-cooled slider (5); Step 3: Develop the welding process, materials, and operating methods for gas slag shielded welding, including wire spacing, triangular oscillation width, dwell time, welding torch position, welding torch angle, root and face welding parameters, and welding backing. Step 4: Achieve mechanized and automated welding of single-sided welding with double-sided one-time forming and gas slag protection for horizontal butt joints; Step 5: Post-weld treatment. If undercut or incomplete welding occurs at the upper bevel after welding, it must be repaired with carbon dioxide gas shielded welding. The hardware for the dedicated transverse EGW welding equipment includes: Welding machine, wire feeder, water tank, welding wire, horizontal special welding trolley equipment body and operation box (3); The main body of the transverse special welding trolley equipment includes an up-and-down swing device (1) and a front-and-back swing device (2). The welding machine includes a conductive nozzle (4); The water-cooled slider (5) includes a base plate (501) and a bent vertical plate (502). The bent vertical plate (502) is installed on one end of the upper wall of the base plate (501), and the angle between the bent vertical plate (502) and one end of the wall of the base plate (501) is 50°. A semi-glasses-shaped groove (503) is provided on the lower wall of the base plate (501). The bevel type is: a single-sided V-shaped bevel, and the bevel angle is 45° at the top of the bevel and 0°~2° at the bottom of the bevel. The bevel gap is 4~8mm; The width of the triangular swing is: the forward and backward swing width of the welding torch triangular swing shape is 5~6mm, and the vertical swing width of the welding torch triangular swing shape is 4~8mm. The welding torch position includes: when the welding torch is swinging in a triangular shape and not welding, the position of the welding torch in the stopped state is at the root position of the triangular swing, the distance between the root position and the lower bevel of the horizontal butt joint is 3~4mm, and the distance between the root position and the root of the bevel is 1~2mm. The welding wire used is of grade SC-EGH, Φ1.4mm; When the plate thickness is 7.5-9mm, the root current is 250-260 A, the surface current is 260-270 A, the root voltage is 29-30V, the surface voltage is 30-32V, the welding speed is 125mm / min, the root dwell time is 0.4s, the surface dwell time is 0.8s-1.0s, the oscillation width is 5-6mm, and the oscillation speed is 12-14mm / s. When the plate thickness is 9-10.5mm, the root current is 260-280A, the surface current is 270-285A, the root voltage is 29-31V, the surface voltage is 30-33V, the welding speed is 107mm / min, the root dwell time is 0.6s, the surface dwell time is 0.8s-1.1s, the oscillation width is 5-7mm, and the oscillation speed is 12-15mm / s.

2. The welding method for horizontal welding of PCTC ship thin plates according to claim 1, characterized in that, The welding wire is 30~35mm long.

3. The welding method for horizontal welding of PCTC ship thin plates according to claim 1, characterized in that, The dwell time is as follows: when the welding torch swings in a triangular pattern, the dwell time at the root of the bevel is 0.5 seconds, the dwell time at the upper part of the bevel surface is 0.8 seconds, and the dwell time at the lower part of the bevel surface is 1.1 seconds, with a swing speed of 14 mm / sec.

4. The welding method for horizontal welding of PCTC ship thin plates according to claim 1, characterized in that, The welding torch angle includes: when welding materials with a thickness of 7.5mm to 10.5mm, the welding torch forms an angle of 3° to 4° with the plate surface.

5. The welding method for horizontal welding of PCTC ship thin plates according to claim 1, characterized in that, The conductive tip (4) is made of chromium zirconium copper material. The specifications of the conductive tip (4) are Φ1.42*M6*45mm and the external dimensions of the conductive tip (4) are pointed cone M6*3.4mm.

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