High-speed submerged arc welding method and system

Abstract

The invention belongs to the technical field of submerged arc welding, and discloses a high-speed submerged arc welding method and system. In the submerged-arc welding process, special waveform control is adopted, that is, periodic voltage amplitude control is adopted for the welding voltage, cyclic control is conducted between the high-voltage period and the low-voltage period, and electric arcs in the high-voltage state and the low-voltage state repeatedly act on the combination position of the two base materials; and meanwhile, the welding current and the welding voltage are kept to have the same change trend. In the high voltage period, a rotating jet flow transition mode is adopted to blow away molten metal to expose unmolten base metal, meanwhile, the metal side wall of a molten pool is supported, the shape of the molten pool is kept, and electric arcs are stabilized; in the low-voltage period, a large-drop-shaped transition mode is adopted, the top end of the welding wire is lower than the base metal, and the bottom of the base metal is heated to increase the fusion depth. According to the invention, thick plate welding can be carried out by combining a welding wire with a smaller diameter with a general welding flux, and the method has the advantages of high wire feeding speed, increased penetration depth, narrowed weld bead, improved welding quality and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of submerged arc welding, and in particular relates to a high-speed submerged arc welding method and system. Background Art

[0002] like Figure 1 As shown in the figure, the traditional submerged arc welding system is mainly composed of submerged arc welding power source, submerged arc welding carriage, welding gun, welding wire and flux. Figure 2 As shown, during welding, the front end of the welding wire will be buried under the flux, so that the arc burns under the flux layer, thereby fusing the welding wire, flux and base material to achieve submerged arc welding operation.

[0003] However, traditional submerged arc welding technology often has the following problems in practical applications:

[0004] 1. The welding wire is relatively thick, with a diameter generally above 2.4mm, which results in a large volume of single-disc welding wire and inconvenient installation and replacement;

[0005] 2. The plate (i.e., parent material) is thicker and the welding wire is thicker, which requires a higher input power during welding, that is, a large-capacity welding power source is required. In addition, in terms of current control, traditional submerged arc welding technology generally adopts constant current control;

[0006] 3. The wire feeding speed is slow, generally below 10m / min;

[0007] 4. Submerged arc welding equipment is complex, costly, and requires a lot of maintenance work;

[0008] 5. In order to increase the penetration depth, multiple electrodes or increasing the welding current are used, resulting in large deformation after welding;

[0009] 6. The submerged arc welding trolley is fixed on the track and its applicable position is limited. It is only suitable for flat welding on a preset track. Summary of the invention

[0010] The purpose of the present invention is to propose a high-speed submerged arc welding method, which realizes a new submerged arc welding mode by controlling the waveform during the submerged arc welding process. This welding method can use a thinner diameter welding wire in combination with a universal flux to weld thick plates, and has the advantages of fast wire feeding speed, increased penetration, narrower weld bead, improved welding quality and efficiency, etc.

[0011] In order to achieve the above object, the present invention adopts the following technical scheme:

[0012] A high-speed submerged arc welding method comprises the following steps:

[0013] An arc is formed at the junction of the tip of the welding wire and two parent materials, namely, the first parent material and the second parent material, so that a molten pool is formed at the junction of the first parent material and the second parent material, and the welding wire is fed to fill the molten welding wire in the molten pool;

[0014] Under the protection of the flux, the molten metal is filled into the molten pool, and after cooling, a weld is formed, thus achieving the fusion of the two base materials;

[0015] During the submerged arc welding process, the welding voltage is controlled by periodic voltage amplitude, that is, the arc is repeatedly applied to the joint of the two base materials in the high voltage and low voltage states.

[0016] During high voltage, the rotating jet transition method is adopted. The arc blows away the molten metal to expose the unmelted parent metal, while supporting the side wall of the molten pool metal, maintaining the shape of the molten pool and stabilizing the arc. During low voltage, the large droplet transition method is adopted. The top of the welding wire is lower than the height of the parent metal. The arc heats the bottom of the two parent metals to increase the melting depth.

[0017] During the submerged arc welding process, the welding current and welding voltage are maintained to have the same periodic change trend.

[0018] In addition, based on the above-mentioned high-speed submerged arc welding method, the present invention also proposes a corresponding high-speed submerged arc welding system, which adopts the following technical solutions:

[0019] A high-speed submerged arc welding system comprises a welding gun, a welding power source, a wire feeding mechanism and a flux; wherein the welding power source is connected to a conductive nozzle of the welding gun and a base material through a cable to form a welding circuit;

[0020] An arc is formed at the junction of the top end of the welding wire and two base materials, namely, the first base material and the second base material, so that a molten pool is formed at the junction of the first base material and the second base material, and the welding wire is fed through the wire feeding mechanism to fill the molten welding wire in the molten pool;

[0021] Under the protection of the flux, the molten metal is filled into the molten pool, and after cooling, a weld is formed, thus achieving the fusion of the two base materials;

[0022] During submerged arc welding, the welding power source outputs periodically changing welding voltage and welding current;

[0023] The welding voltage is controlled by periodic voltage amplitude, that is, the welding voltage is controlled cyclically between high voltage period and low voltage period, and the arc in high voltage and low voltage state is repeatedly applied to the joint of two base materials.

[0024] During high voltage, the rotating jet transition method is adopted. The arc blows away the molten metal to expose the unmelted parent metal, while supporting the side wall of the molten pool metal, maintaining the shape of the molten pool and stabilizing the arc. During low voltage, the large droplet transition method is adopted. The top of the welding wire is lower than the height of the parent metal. The arc heats the bottom of the two parent metals to increase the melting depth.

[0025] During the submerged arc welding process, the welding current and welding voltage are maintained to have the same periodic change trend.

[0026] The present invention has the following advantages:

[0027] As described above, the present invention relates to a high-speed submerged arc welding method and system. The method of the present invention adopts a special waveform control (i.e., voltage and current control) in the submerged arc welding scene to replace the traditional submerged arc welding method, thereby realizing a new submerged arc welding method. Specifically, in the submerged arc welding process, the welding voltage adopts voltage amplitude control, that is, by cyclically controlling between the high voltage period and the low voltage period. At the same time, in the submerged arc welding process, the welding current and the welding voltage are kept to have the same periodic change trend, thereby generating two kinds of droplet transition modes in the large current domain, namely, large droplet transition and rotating jet transition, and obtaining a large penetration depth and a stable submerged arc interval at the same time. Compared with the traditional submerged arc welding process, since the present invention adopts a special waveform control method in the submerged arc welding process, only a thinner welding wire (i.e., a welding wire with a diameter less than 2.4 mm) is required in the welding process. At the same time, because the penetration depth is deeper, this new submerged arc welding method has more filling wire than the traditional submerged arc welding, so the wire feeding speed is faster, which can reach more than 10m / min. In addition, the present invention uses a thinner welding wire to form a narrower weld bead, thereby obtaining a small width-to-depth ratio weld bead with a narrow weld bead and deep penetration. The method of the present invention has high welding efficiency, small deformation of the plate after welding, high welding quality, and beautiful welds. In addition, the present invention also provides a high-speed submerged arc welding system that uses the same inventive concept as the above-mentioned high-speed submerged arc welding method. The system provides a welding power supply with special waveform control to replace the traditional submerged arc welding machine. The welding power supply with special waveform control is applied to the submerged arc welding scene to realize a new submerged arc welding method. Compared with the shortcomings of traditional submerged arc welding equipment such as complexity, high cost, and large maintenance workload, the welding power supply in the present invention only needs to use a conventional gas shielded welding power supply, and its equipment is simple, the cost is low, and the maintenance workload is low. In addition, since the present invention adopts a welding wire with a smaller diameter, the wire feeding mechanism and the welding gun do not need to use large-diameter wire feeding wheels, wire guide tubes and other components, and the overall weight will be lighter. In this way, in addition to using the traditional submerged arc welding trolley, a mechanical arm with a lighter load-bearing capacity can also be used to replace the submerged arc welding trolley, thereby solving the problem that the submerged arc welding trolley can only be used for positioning welding on the track. Compared with the traditional submerged arc welding method in which the submerged arc welding trolley is fixed on the track and travels, the applicable position is limited, and it can only be used for flat welding on a set track, multi-directional submerged arc welding can be achieved through the mechanical arm. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the composition of the traditional submerged arc welding system;

[0029] Figure 2 This is a schematic diagram of the submerged arc welding principle;

[0030] Figure 3 Schematic diagram of the principle of the high-speed submerged arc welding method in an embodiment of the present invention;

[0031] Figure 4 It is a state display diagram of two droplet transfer modes in an embodiment of the present invention;

[0032] Figure 5 A schematic diagram of changes in welding voltage, welding current and wire feeding speed during welding in an embodiment of the present invention;

[0033] Figure 6 Schematic diagram of arc state during high and low voltage in an embodiment of the present invention; Figure 6 (a) in the figure shows the low voltage arc state. Figure 6 (b) in the figure shows the high voltage arc state;

[0034] Figure 7 It is a schematic diagram of weld formation under different welding current and voltage conditions in a specific example of the present invention;

[0035] Figure 8 Schematic diagram of plate deformation before and after welding in a specific example of the present invention; Figure 8 The upper plate in the figure shows the state of the plate before welding. Figure 8 The lower plate in the figure is a schematic diagram of the plate state after welding;

[0036] Fig. 9 Schematic diagram of penetration depth under different welding current and voltage conditions in a specific example of the present invention; wherein (a) is a cross-sectional diagram of penetration depth formed under different welding current and voltage conditions, and (b) is a schematic diagram of penetration depth measurement;

[0037] Fig.10 A schematic diagram of a conventional submerged arc welding trolley in an embodiment of the present invention;

[0038] Fig.11 It is a schematic diagram of the principle of large droplet transition and rotating jet transition in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] Glossary:

[0040] The droplet transfer mode refers to the different transition modes of the droplet transfer under different welding output current ranges, including short-circuit transition, large droplet transition, sub-jet transition, jet transition, rotating jet transition and other states.

[0041] The state of droplet transfer has reached a broad industry consensus in the field of welding. In metal arc welding, the droplet transfer mode is mainly determined by the applied welding current, shielding gas content, etc. Globular transfer and rotary transfer are each one of the droplet transfer modes.

[0042] like Fig.11 As shown in the figure, large droplet transition is a way of metal transfer on the arc, in which a molten ball larger than the electrode diameter is formed at the tip of the electrode. Rotating jet transition means that after the arc enters the jet transition, the welding current continues to increase to a certain stage. Under the influence of electromagnetic force, the arc will deflect in the longitudinal direction, and the molten droplet will rotate at high speed.

[0043] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0044] Example 1

[0045] This embodiment 1 describes a high-speed submerged arc welding method, which implements a new submerged arc welding method by adopting special waveform control (ie, voltage and current control) in a submerged arc welding scenario to replace the traditional submerged arc welding method.

[0046] like Figure 3 As shown, the purpose of the welding method of the present invention is to fuse the first parent material A and the second parent material B together.

[0047] First, the welding power source is connected to the conductive nozzle and the base material through cables to form a welding circuit.

[0048] When the welding power supply outputs welding voltage and welding current, an arc is formed at the junction of the top end of the welding wire and the first parent material A and the second parent material B, thereby forming a molten pool at the junction of the first parent material A and the second parent material B.

[0049] (Through Figure 3 The wire feeding mechanism shown in the figure feeds the welding wire and fills the molten welding wire into the molten pool. Under the protection of the flux, the molten metal is filled into the molten pool and forms a weld after cooling, thus realizing the fusion of the two base materials A and B.

[0050] During the submerged arc welding process, the welding voltage is controlled by periodic voltage amplitude, that is, it is cyclically controlled between high voltage periods and low voltage periods, and the arc in high voltage and low voltage states is repeatedly applied to the junction of base materials A and B.

[0051] During the submerged arc welding process, the welding current and welding voltage are maintained to have the same periodic change trend.

[0052] The welding voltage can be controlled by cycling between high and low voltages to produce two types of droplet transfer in the high current domain, namely large droplet transfer and rotating jet transfer, such as Figure 4 As shown, a large melting depth and a stable arc submersion range are obtained at the same time.

[0053] Here, the high current region refers to a region where the current is higher than 500A.

[0054] Submerged arc space refers to the space formed by the tip of the welding wire in the molten metal when an arc is generated. If the tip of the welding wire is lower than the surface of the parent material, the submerged arc space is larger; if the tip of the welding wire is higher than the surface of the parent material, the submerged arc space is smaller.

[0055] Through periodic voltage fluctuation control, the latent arc space can be stabilized and a weld with uniform width can be obtained.

[0056] When the output voltage of the welding power source changes between high and low voltages, a periodically changing output current is also obtained. The welding current has the same periodic variation trend as the welding voltage, thereby achieving large droplet transition or rotating jet transition.

[0057] like Figure 4 As shown in the figure, during the high voltage period, the rotating jet transfer method is used. The arc blows away the molten metal to expose the unmelted parent metal, while supporting the side wall of the molten pool metal, maintaining the shape of the molten pool and stabilizing the arc. During the low voltage period, the large droplet transfer method is used. The top of the welding wire is lower than the height of the parent metal. The arc heats the bottom of the two parent metals to increase the penetration depth.

[0058] More specifically, after the welding voltage is converted from a low voltage period to a high voltage period, the voltage increases, the current also increases, the melting speed of the welding wire is accelerated, a liquid column is formed at the top of the welding wire, the position of the top of the welding wire is increased, the arc becomes wider, and the arc pressure decreases at this time; after the welding voltage is converted from a high voltage period to a low voltage period, the voltage decreases, the current also decreases accordingly, the melting speed of the welding wire slows down, a large molten droplet is formed at the top of the welding wire, the position of the top of the welding wire is lowered, the arc becomes narrower, and the arc pressure increases at this time.

[0059] During the high voltage period, the relatively wide arc begins to rotate, blowing away the liquid metal at the bottom of the latent arc space to expose the unmelted base material. When switching from the high voltage period to the low voltage period, as the arc pressure increases, the large molten droplet formed at the top of the welding wire hammers to the bottom of the base material under the pressure of the arc, melting the metal at the bottom of the base material and increasing the depth of fusion.

[0060] Here, the relatively wider arc during the high voltage period is relative to the arc during the low voltage period.

[0061] like Figure 5 As shown, the welding voltage is a fluctuating voltage. When the set voltage is V0, the output voltage oscillates back and forth within the amplitude range of the first welding voltage V1 and the second welding voltage V2 with V0 as the center and time T as the time period, forming a high and low voltage alternation. Among them, the first welding voltage V1 is greater than the set voltage V0, and the set voltage V0 is greater than the second welding voltage V2.

[0062] Each time period T includes four stages, namely, time t1 to t2, time t2 to t3, time t3 to t4, and time t4 to t5; wherein, time t1 and t5 are the start and end times of a time period T, respectively.

[0063] The time from t1 to t2 and the time from t3 to t4 correspond to the transition period from the second welding voltage to the first welding voltage and from the first welding voltage to the second welding voltage, respectively. The time from t2 to t3 is the high voltage period, and the time from t4 to t5 is the low voltage period.

[0064] Similarly, the welding current is a fluctuating current, which has the same variation trend as the welding voltage. That is, during the high voltage period, the welding current is set to the first welding current Ip, and during the low voltage period, the welding current is set to the second welding current Ib, wherein the first welding current Ip is greater than the second welding current Ib. The welding current oscillates back and forth within the amplitude range of Ip and Ib with a time period of T, forming alternation of high and low currents.

[0065] During the entire welding process, a constant wire feeding speed S0 is maintained, which can reach over 10 m / min.

[0066] Since this embodiment uses thinner welding wire, that is, welding wire with a diameter less than 2.4 mm, and because the penetration depth is deeper, this new submerged arc welding method requires more filling wire than traditional submerged arc welding, and thus the wire feeding speed is faster.

[0067] Although the set voltage can be changed at a faster speed, the welding current set in this embodiment is not as fast as the welding current set in this embodiment due to the presence of inductance and related adjustable parameters in the welding machine hardware. Figure 5 This embodiment uses OTC's unique Welbee precision waveform control to make the welding current present a waveform with a certain arc (from t2 to t3), as shown in FIG. Figure 5 shown.

[0068] The present invention utilizes external characteristic control (i.e., the relationship between the output current and the output voltage of the welding power supply when the load changes. In this embodiment, the welding power supply adopts flat characteristic control) and voltage fluctuation composite control to obtain a uniform weld.

[0069] In this embodiment, the adjustment range of the set voltage V0 is [10V, 55V]. When the fluctuation amplitude of the set voltage V0 is not 0, the set voltage is a periodic fluctuating voltage, and the adjustable range of the voltage fluctuation frequency is between 0.2 Hz-500 Hz.

[0070] Figure 5 The high voltage V1 in Figure 5The adjustment range of the low voltage V2 is (0,30V], wherein the high voltage and the low voltage here are relative, that is, referring to the first welding voltage and the second welding voltage mentioned above.

[0071] like Figure 6 As shown in the figure, when the arc is in the low voltage period from t4 to t5, the arc length is L1, and the arc root area is S1. At this time, compared with the high voltage period, the current is reduced, the arc length L1 is shorter, the position of the top of the welding wire is lower, the arc root area is smaller, and the arc pressure increases. When the arc is in the high voltage period from t2 to t3, the voltage increases, the current also increases, the welding wire melts quickly, and the position of the top of the welding wire rises. The arc length during the high voltage period is defined as L2, and the arc root area is S2. At this time, compared with the low voltage period, the arc length is longer, the arc root area is larger, that is, L2 is greater than L1, S2 is greater than S1, and the arc pressure decreases.

[0072] The method of the present invention repeatedly applies arcs with high and low voltages to a liquid metal molten pool. Due to the periodic change of the arc pressure, a hammering effect is formed on the molten pool, causing the molten pool to move downward and stir in the opposite direction of the arc. At this time, the metal droplets formed at the front end of the welding wire will fill the molten pool, thereby obtaining a greater melting depth.

[0073] Compared with traditional submerged arc welding, the new submerged arc welding method adopted in the present invention adopts a welding wire with a diameter of less than 2.4 mm. Because the penetration depth is deeper and the filling wire is more than that of traditional submerged arc welding, the wire feeding speed is faster and can reach more than 10 m / min. In addition, the thinner welding wire forms a narrower weld bead, thereby obtaining a weld bead with a narrow weld bead, deep penetration and a small width-to-depth ratio.

[0074] As shown in Table 1 below, some parameters of the submerged arc welding method of the present invention and the conventional submerged arc welding are compared:

[0075] Table 1 Comparison of parameters between the present invention and conventional submerged arc welding

[0076] Conventional submerged arc welding Submerged arc welding method of the present invention Wire diameter >φ2.4mm <φ2.4mm Wire feeding speed <10m / min >10m / min Walking device Submerged arc welding trolley Submerged arc welding trolley or robotic arm Melt Depth shallow deep Aspect Ratio big Small

[0077] It is not difficult to see from Table 1 that after adopting the new submerged arc welding method proposed in the present invention, the diameter of the welding wire is significantly reduced, not exceeding 2.4 mm, while the penetration depth is increased, and the wire feeding speed is faster, exceeding 10 m / min.

[0078] In addition, as the diameter of the welding wire is reduced, the installation of the wire feeding mechanism and the like is more flexible, and the corresponding walking device can be a submerged arc welding trolley or a robotic arm. This solves the problem that the traditional submerged arc welding method can only use a submerged arc welding trolley fixed on a track, with limited applicable positions and can only be used for plane welding on a set trajectory.

[0079] In addition, after adopting the new submerged arc welding method proposed by the present invention, compared with the traditional submerged arc welding method, the penetration depth is increased and the weld is narrowed, so the width-to-depth ratio of the weld finally formed is reduced, which is more reasonable.

[0080] In order to better illustrate the effectiveness of the method of the present invention, the following Figures 7 to 9 The displayed weld formation diagram, plate deformation diagram, penetration diagram and several sets of measured data are shown in Table 2 below.

[0081] Figure 7 From left to right in the figure, the weld formation diagram is shown when the welding current is selected as 700A, 600A, 500A respectively, and the corresponding welding voltage is selected as 51V, 46V and 42V.

[0082] Figure 8 The figure shows the deformation of the plate (i.e., parent material) before and after welding.

[0083] Fig. 9 From left to right, the depth of penetration is shown when the welding current is selected as 700A, 600A, and 500A respectively, and the corresponding welding voltage is selected as 51V, 46V, and 42V. (a) is the formed depth of penetration, and (b) is the measured depth of penetration value.

[0084] Table 2 Measured data

[0085]

[0086]

[0087] It is not difficult to see from the above data that, through the new submerged arc welding method proposed in the present invention, the weld appearance is smooth and beautiful, the deformation is small, the weld bead becomes narrower, the penetration depth of the deep-penetration submerged arc can reach 17mm at 700A, and the deep-penetration submerged arc welding efficiency is high.

[0088] Example 2

[0089] This embodiment 2 describes a high-speed submerged arc welding system, which adopts the same inventive concept as the high-speed submerged arc welding method mentioned in the above embodiment 1.

[0090] like Figure 3 As shown, this embodiment uses a welding power supply with special waveform control to replace the traditional submerged arc welding machine, and applies the welding power supply to the submerged arc welding scene to realize a new submerged arc welding method.

[0091] This system can use thinner welding wire below φ2.4mm in diameter and general flux to weld thick plates. The wire feeding speed can reach over 10m / min, the penetration depth is increased, the weld width is narrowed, the submerged arc welding efficiency is improved, and the width-to-depth ratio of the weld is more reasonable.

[0092] Specifically, the high-speed submerged arc welding system in this embodiment includes a welding gun, a welding power source, a wire feeding mechanism and a flux; wherein the welding power source is connected to the conductive nozzle of the welding gun and the base material through a cable to form a welding circuit.

[0093] An arc is formed at the junction of the top end of the welding wire and the first parent material A and the second parent material B, thereby forming a molten pool at the junction of the first parent material and the second parent material. The welding wire is fed through the wire feeding mechanism to fill the molten welding wire in the molten pool.

[0094] Under the protection of the flux, the molten metal is filled into the molten pool, and a weld is formed after cooling, realizing the fusion of the two base materials.

[0095] During the submerged arc welding process, the welding power supply outputs periodically changing welding voltage and welding current.

[0096] The welding voltage is controlled by periodic voltage amplitude, that is, it is cyclically controlled between high voltage period and low voltage period, and the arc in high voltage and low voltage state is repeatedly applied to the joint of base materials A and B.

[0097] During high voltage, the rotating jet transition method is used. The arc blows away the molten metal to expose the unmelted parent metal, while supporting the side wall of the molten pool metal, maintaining the shape of the molten pool and stabilizing the arc. During low voltage, the large droplet transition method is used. The top of the welding wire is lower than the height of the parent metal. The arc heats the bottom of the two parent metals to increase the depth of penetration.

[0098] During the submerged arc welding process, the welding current and welding voltage are maintained to have the same periodic change trend.

[0099] In addition, during the submerged arc welding process, a constant wire feed speed of more than 10 m / min is maintained.

[0100] The present invention solves the defects of traditional submerged arc welding equipment, such as complexity and heavy maintenance workload, reduces the equipment cost of customers and the technical requirements of operators, and makes the debugging of relevant welding parameters such as current, voltage and wire feeding speed simpler.

[0101] like Fig.10 A schematic diagram of a traditional submerged arc welding trolley is shown. In traditional submerged arc welding, due to the heavy wire feeder mechanism, only a heavy-load submerged arc welding trolley can be used, which carries components such as a wire feeder mechanism, a wire reel shaft, a welding gun, and a flux funnel.

[0102] Since the present invention uses a thinner diameter welding wire, the weight of the welding wire is greatly reduced, so that the wire feeding mechanism, welding gun, etc. do not need to use large diameter wire feeding wheels, wire guide tubes and other components, and the overall weight will be lighter. Therefore, in addition to being mounted on a traditional submerged arc welding trolley, a mechanical arm with a lighter load capacity can also be used to replace the submerged arc welding trolley, thereby solving the problem of only being able to use the submerged arc welding trolley for positioning welding on the track, and realizing multi-directional submerged arc welding.

[0103] When welding with a lighter load robot, the method is the same as the current metal arc welding.

[0104] Of course, the above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiments. It should be noted that all equivalent substitutions and obvious deformation forms made by any technician familiar with the field under the guidance of this specification fall within the essential scope of this specification and should be protected by the present invention.

Claims

1. A high-speed submerged arc welding method, characterized in that: The steps include: An arc is formed at the junction of the tip of the welding wire and two parent materials, namely, the first parent material and the second parent material, so that a molten pool is formed at the junction of the first parent material and the second parent material, and the welding wire is fed to fill the molten welding wire in the molten pool; Under the protection of the flux, the molten metal is filled into the molten pool, and after cooling, a weld is formed, thus achieving the fusion of the two base materials; During the submerged arc welding process, the welding voltage is controlled by periodic voltage amplitude, that is, the arc is repeatedly applied to the joint of the two base materials in the high voltage and low voltage states. During high voltage, the rotating jet transition method is adopted. The arc blows away the molten metal to expose the unmelted parent metal, while supporting the side wall of the molten pool metal, maintaining the shape of the molten pool and stabilizing the arc. During low voltage, the large droplet transition method is adopted. The top of the welding wire is lower than the height of the parent metal. The arc heats the bottom of the two parent metals to increase the melting depth. During the submerged arc welding process, the welding current and welding voltage are maintained to have the same periodic change trend.

2. The high-speed submerged arc welding method according to claim 1, characterized in that: The welding voltage is a fluctuating voltage. When the voltage is set to V0, the output voltage is centered on V0 within the amplitude range of the first welding voltage V1 and the second welding voltage V2, and oscillates back and forth with a time period of T, forming alternating high and low voltages; The first welding voltage V1 is greater than the set voltage V0, and the set voltage V0 is greater than the second welding voltage V2.

3. The high-speed submerged arc welding method according to claim 2, characterized in that: The adjustment range of the set voltage V0 is [10V, 55V]; The adjustment range of the first welding voltage V1 and the second welding voltage V2 is (0, 30V).

4. The high-speed submerged arc welding method according to claim 1, characterized in that: The welding current is a fluctuating current. During a high voltage period, the welding current is set to a first welding current Ip, and during a low voltage period, the welding current is set to a second welding current Ib, wherein the first welding current is greater than the second welding current; The welding current oscillates back and forth within the amplitude range of Ip and Ib with a time period of T, forming alternation of high and low currents.

5. The high-speed submerged arc welding method according to claim 1, characterized in that: After the welding voltage is switched from the low voltage period to the high voltage period, the voltage increases, the current also increases, the melting speed of the welding wire is accelerated, a liquid column is formed at the top of the welding wire, the position of the top of the welding wire is raised, the arc becomes wider, and the arc pressure is reduced at this time; When the welding voltage is switched from high voltage to low voltage, the voltage decreases, the current also decreases, the melting speed of the welding wire slows down, a large molten droplet is formed at the top of the welding wire, the position of the top of the welding wire is lowered, the arc becomes narrower, and the arc pressure increases at this time; During the high voltage period, the arc begins to rotate, blowing away the liquid metal at the bottom of the latent arc space to expose the unmelted base material. When switching from the high voltage period to the low voltage period, as the arc pressure increases, the large molten droplet formed at the top of the welding wire hammers to the bottom of the base material under the pressure of the arc, melting the metal at the bottom of the base material and increasing the depth of fusion.

6. The high-speed submerged arc welding method according to claim 1, characterized in that: During the welding process, a constant wire feeding speed is maintained, which is greater than 10 m / min; and the diameter of the welding wire is less than 2.4 mm.

7. The high-speed submerged arc welding method according to claim 1, characterized in that: Each time period T includes four stages, namely, time t1 to time t2, time t2 to time t3, time t3 to time t4, and time t4 to time t5; wherein time t1 and time t5 are the start and end time of a time period T respectively; The time from t1 to t2 and the time from t3 to t4 correspond to the transition period from the second welding voltage to the first welding voltage and from the first welding voltage to the second welding voltage, respectively. The time from t2 to t3 is a high voltage period, and the time from t4 to t5 is a low voltage period.

8. The high-speed submerged arc welding method according to claim 7, characterized in that: When the arc is in the low voltage period from t4 to t5, the arc length is L1 and the arc root area is S1. Compared with the high voltage period, the current is reduced, the arc length L1 is shorter, the position of the top of the welding wire is lower, the arc root area is smaller, and the arc pressure increases; When the arc is in the high voltage period from t2 to t3, the voltage increases, the current also increases accordingly, the welding wire melts quickly, and the top position of the welding wire rises. The arc length during the high voltage period is defined as L2, and the arc root area is defined as S2. At this time, compared with the low voltage period, the arc length is longer and the arc root area is larger, that is, L2 is greater than L1, and S2 is greater than S1, and the arc pressure is reduced.

9. A high-speed submerged arc welding system, characterized in that: It includes a welding gun, a welding power source, a wire feeding mechanism and a soldering flux; wherein the welding power source is connected to the conductive nozzle of the welding gun and the base material through a cable to form a welding circuit; An arc is formed at the junction of the top end of the welding wire and two base materials, namely, the first base material and the second base material, so that a molten pool is formed at the junction of the first base material and the second base material, and the welding wire is fed through the wire feeding mechanism to fill the molten welding wire in the molten pool; Under the protection of the flux, the molten metal is filled into the molten pool, and after cooling, a weld is formed, thus achieving the fusion of the two base materials; During submerged arc welding, the welding power source outputs periodically changing welding voltage and welding current; The welding voltage is controlled by periodic voltage amplitude, that is, the welding voltage is controlled cyclically between high voltage period and low voltage period, and the arc in high voltage and low voltage state is repeatedly applied to the joint of two base materials. During high voltage, the rotating jet transition method is adopted. The arc blows away the molten metal to expose the unmelted parent metal, while supporting the side wall of the molten pool metal, maintaining the shape of the molten pool and stabilizing the arc. During low voltage, the large droplet transition method is adopted. The top of the welding wire is lower than the height of the parent metal. The arc heats the bottom of the two parent metals to increase the melting depth. During the submerged arc welding process, the welding current and welding voltage are maintained to have the same periodic change trend.

10. The high-speed submerged arc welding system according to claim 9, characterized in that: The wire feeding mechanism is mounted on a submerged arc welding trolley running along a fixed track, or on a mechanical arm.

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