An underwater high-pressure plasma arc starting device and arc starting method thereof

Abstract

The present invention provides an underwater high-pressure plasma arc starting device and an arc starting method thereof, relating to the technical field of plasma arc welding. The underwater high-pressure plasma arc starting device is characterized by comprising a working chamber for providing a high-pressure environment, an ion-gas mixing component, and a gas-electricity combined control module. A plasma arc welding gun is provided in the working chamber. The gas-electricity combined control module is simultaneously connected to the ion-gas mixing component and the plasma arc welding gun for control. The ion-gas mixing component and the plasma arc welding gun are connected and communicated. The ion-gas mixing component is used to mix low-ionization energy gas and ion gas and deliver the mixed gas to the plasma arc welding gun. The present invention solves the problem of difficult ionization of ion gas in a high-pressure environment by combining the plasma arc welding gun, the ion-gas mixing component, and the gas-electricity combined control module to achieve stable arc starting and welding process of the plasma arc in an underwater high-pressure environment.

Description

Technical Field

[0001] The present invention relates to the technical field of plasma arc welding, and in particular to an underwater high-pressure plasma arc starting device and an arc starting method thereof. Background Art

[0002] my country has abundant offshore oil and natural gas resources. With the development and utilization of marine oil and gas resources, the number of submarine underwater oil pipelines will inevitably increase gradually. However, due to the harsh environment in which submarine underwater oil pipelines are located, they are prone to damage due to accidental mechanical impact, internal and external corrosion from seawater and oil and gas, and aging. Underwater welding maintenance is the fastest and most reliable method for emergency repair of submarine underwater pipelines. Among them, underwater high-pressure dry welding is recognized as the preferred method for underwater welding maintenance due to its good welding quality. At present, the main arc welding methods used for underwater high-pressure dry welding are tungsten inert gas welding (GTAW) and gas metal arc welding (GMAW). However, since the arcs of both are free arcs, as the water depth increases, the ambient pressure increases, and the welding arc shrinks, the welding process gradually becomes unstable, resulting in a decline in welding quality.

[0003] As an advanced technology of the free arc, the plasma arc boasts significantly superior energy density and directivity due to its highly confined nature. It is considered one of the three high-energy beams, along with the laser and electron beams. As a specialized arc, the plasma arc combines the advantages of both the free arc and the high-energy beam. Not only does it offer significant advantages in equipment cost, working environment, and welding gun flexibility, but it also boasts higher arc quality. Applying plasma arc welding technology to underwater high-pressure welding will undoubtedly produce even higher-quality welds.

[0004] However, existing research shows that air plasma arc cutting power supplies can only strike an arc at a gauge pressure of 0.2 MPa. Even after adding a high-frequency arc starter to boost the pressure, reliable arc striking can only be achieved at 0.4 MPa. Therefore, stable arc striking in high-pressure environments has become a key issue restricting its application. Summary of the Invention

[0005] In view of this, one of the purposes of the present invention is to provide an underwater high-pressure plasma arc starting device to solve the technical problem in the prior art that after the air plasma arc cutting power supply is modified by adding a high-frequency arc starter for voltage boosting, the arc starting pressure increase is limited, resulting in the stable arc starting of the plasma arc in a high-pressure environment becoming a restriction.

[0006] A second object of the present invention is to provide an underwater high-pressure plasma arc starting method.

[0007] In order to achieve one of the above-mentioned purposes, the present invention provides an underwater high-pressure plasma arc starting device, including a working chamber for providing a high-pressure environment, an ion-gas mixing component and a gas-electric combined control module, a plasma arc welding gun is provided in the working chamber, the gas-electric combined control module is simultaneously controlled and connected to the ion-gas mixing component and the plasma arc welding gun, the ion-gas mixing component and the plasma arc welding gun are connected and communicated, and the ion-gas mixing component is used to mix low ionization energy gas and ion gas, and transport the mixed gas to the plasma arc welding gun.

[0008] According to an optional embodiment, the ion-gas mixing assembly is configured as an inverted Y-shaped structure.

[0009] According to an optional embodiment, a low ionization energy gas cylinder and an ion gas cylinder are provided below the ion gas mixing assembly, and the low ionization energy gas cylinder and the ion gas cylinder are connected to and communicated with the ion gas mixing assembly.

[0010] According to an optional embodiment, the ion gas mixing assembly is provided with a gas flow controller for controlling the flow rate of the low ionization energy gas and the ion gas, and a high-frequency electromagnetic valve for controlling the start and stop of the low ionization energy gas and the ion gas.

[0011] According to an optional embodiment, the low ionization energy gas includes but is not limited to xenon and carbon monoxide, and the ion gas is argon.

[0012] According to an optional embodiment, the low ionization energy gas is mixed with the ion gas, and the proportion of the low ionization energy gas is 50% to 90%.

[0013] In order to achieve the second of the above objectives, the present invention provides an underwater high-pressure plasma arc starting method, comprising the following steps:

[0014] Step S1: adjusting the low ionization energy gas and ion gas in the mixed gas to set values, and establishing a high pressure environment in the working chamber;

[0015] Step S2: operate the gas-electricity combined control module to execute the advance gas supply-arc maintenance program;

[0016] Step S3: Start the main arc switch to establish a stable main arc;

[0017] Step S4: closing the pilot arc;

[0018] Step S5: performing underwater high-pressure dry plasma arc welding.

[0019] According to an optional embodiment, the high-pressure environment pressure value of the working chamber in step S1 is ≥0.15 MPa.

[0020] According to an optional embodiment, the gas supply-arc piloting procedure in step S2 includes opening the low ionization energy gas and ion gas flow control switches, supplying a mixture of low ionization energy gas and ion gas, and starting the arc piloting switch after 10 to 15 seconds to establish a stable arc piloting.

[0021] According to an optional embodiment, closing the pilot arc in step S4 includes closing the low ionization energy gas flow control switch, stopping the low ionization energy gas supply, and immediately increasing the ion gas flow to ensure the stability of the system ion gas flow, and establishing a stable main arc between the plasma arc welding gun and the workpiece.

[0022] The underwater high-pressure plasma arc starting device provided by the present invention has the following technical effects:

[0023] This underwater high-pressure plasma arc starting device includes a working chamber, an ion-gas mixing component and a gas-electric combined control module. A plasma arc welding gun is provided in the working chamber, and the working chamber can provide a high-pressure environment for the plasma arc welding gun. The gas-electric combined control module is simultaneously controlled and connected to the ion-gas mixing component and the plasma arc welding gun. The ion-gas mixing component and the plasma arc welding gun are connected and communicated. The ion-gas mixing component is used to mix low-ionization energy gas and ion gas, and transport the mixed gas to the plasma arc welding gun. The present invention solves the problem of difficult ionization of ion gas in a high-pressure environment by combining the plasma arc welding gun, the ion-gas mixing component and the gas-electric combined control module to achieve stable arc starting and welding process of the plasma arc in an underwater high-pressure environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of an underwater high-pressure plasma arc starting device according to an embodiment of the present invention;

[0026] Figure 2 It is the operating waveform of the gas-electric combined control module.

[0027] in, Figure 1-Figure 2 :

[0028] 1. Working chamber; 2. Plasma arc welding gun; 2. Plasma arc welding power supply; 3. Ion gas mixing assembly; 4. Electrical combined control module; 5. Shielding gas cylinder; 6. Workpiece; 7. Low ionization energy gas cylinder; 8. Ion gas cylinder; 9. Communication cable. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0030] See also Figure 1 , which is a principle structural diagram of an underwater high-pressure plasma arc starting device provided by an embodiment of the present invention. The arc starting device of this embodiment adopts dry plasma arc welding to start the arc.

[0031] Specifically, the underwater high-pressure plasma arc starting device includes a working cabin 1. The working cabin 1 is a commonly used underwater working cabin 1, which is relatively common in the prior art and will not be described in detail in this embodiment.

[0032] See also Figure 1 As shown, a plasma arc welding gun 2 is arranged in the working chamber 1 .

[0033] The main structure of the plasma arc welding gun 2 includes an upper gun body assembly, a lower gun body assembly, a tungsten electrode, an electrode pressure head assembly, an electrode chuck and a nozzle, which are common components in the prior art, so this embodiment does not elaborate on the specific structure of the plasma arc welding gun 2.

[0034] See also Figure 1 As shown, it also includes a gas-electric combined control module 4 and an ion gas mixing component 3. The gas-electric combined control module 4 of this embodiment is simultaneously controlled and connected to the ion gas mixing component 3 and the plasma arc welding gun 2. The control connection between the gas-electric combined control module 4 and the ion gas mixing component 3 is specifically that the gas-electric combined control module 4 and the ion gas mixing component 3 are connected through a communication cable 9, that is, the gas-electric combined control module 4 controls the start and stop of the ion gas mixing component 3 and the mixed gas flow rate; and the control connection between the gas-electric combined control module 4 and the plasma arc welding gun 2 is specifically realized through a plasma arc welding power supply 21 that powers the plasma arc welding gun 2.

[0035] Continue to see Figure 1 As shown, the ion gas mixing component 3 is connected and communicated with the plasma arc welding gun 2 . The function of the ion gas mixing component 3 is to mix the low ionization energy gas and the ion gas, and to deliver the mixed gas to the plasma arc welding gun 2 .

[0036] Specifically, the ion gas mixing assembly 3 is an inverted Y-shaped structure, and a low ionization energy gas cylinder 7 and an ion gas cylinder 8 are provided below the inverted Y-shaped structure. The low ionization energy gas cylinder 7 and the ion gas cylinder 8 are connected and communicated with the ion gas mixing assembly 3, and the low ionization energy gas cylinder 7 and the ion gas cylinder 8 provide low ionization energy gas and ion gas for the ion gas mixing assembly 3; the top of the inverted Y-shaped structure is connected and communicated with the plasma arc welding gun 2, that is, the ion gas mixing assembly 3 can provide mixed gas for the plasma arc welding gun 2.

[0037] It should be noted that the ion gas mixing assembly 3 in this embodiment is not limited to an inverted Y-shaped structure, but can also be other structures. As long as the purpose of mixing low ionization energy gas and ion gas can be achieved, it is within the protection scope of the present invention.

[0038] In order to control the flow of low ionization energy gas and ion gas, the ion gas mixing component 3 has two gas flow control systems, namely a gas flow controller and a high-frequency solenoid valve. The gas flow controller is used to control the flow rate of low ionization energy gas and ion gas, and the high-frequency solenoid valve is used to control the start and stop of low ionization energy gas and ion gas. The mixed gas flow adjustment range is 1.0L / min-6.0L / min.

[0039] In this embodiment, the low ionization energy gas is mixed with the ion gas, and the proportion of the low ionization energy gas is 50% to 90%. Among them, the low ionization energy gas includes xenon (≈12.1eV), carbon monoxide (≈7.86eV), etc., and the ion gas is argon (≈15.76eV).

[0040] The plasma arc welding gun 2 is also connected to and communicated with the shielding gas cylinder 5. Figure 1 As shown, the shielding gas cylinder 5 provides shielding gas for welding to the plasma arc welding gun 2 through the shielding gas path.

[0041] The arc starting device of this embodiment has a simple structure, low cost, is easy to manufacture, and is reliable and practical.

[0042] Corresponding to the arc starting device, another embodiment of the present invention further provides an underwater high-pressure plasma arc starting method, comprising the following steps:

[0043] Step S1: adjusting the low ionization energy gas and ion gas in the mixed gas to set values, and establishing a high pressure environment in the working chamber 1;

[0044] Specifically:

[0045] (1) Based on the constructed underwater high-pressure dry plasma arc welding system, the ion gas (mixed gas) flow rate and shielding gas flow rate are adjusted to the set value of 1.0L / min-6.0L / min;

[0046] (2) According to the set ion gas flow rate and the ratio of low ionization energy gas to ion gas in the mixed gas ((0:1)-(9:1)), the two gas flows are calculated respectively and set in the gas-electricity joint control module 4;

[0047] (3) Fix the workpiece 6 on the workbench and use anhydrous ethanol or acetone to clean the surface of the workpiece 6 for later use, adjust the plasma arc welding gun 2 to the appropriate position; close the door of the working chamber 1, and inflate the chamber to establish the required high-pressure environment (≥0.15MPa).

[0048] Step S2: operating the gas-electricity combined control module 4 to execute the advance gas supply-arc maintenance program;

[0049] Specifically:

[0050] (1) Operate the gas-electricity combined control module 4 to execute the advance gas (mixed gas)-arc starting procedure;

[0051] (2) Open the flow control system of low ionization energy gas (Xe, CO, etc.) and ion gas (Ar), so that the mixed gas of low ionization energy gas and ion gas is sent into ( Figure 2 t0 in the t0);

[0052] (3) Start the arc maintenance switch after 10-15 seconds ( Figure 2 At time t1 in FIG, a stable pilot arc is established between the tungsten electrode and the nozzle of the plasma arc welding gun 2.

[0053] Step S3: Start the main arc switch to establish a stable main arc;

[0054] Specifically: Start the main arc switch ( Figure 2 At time t2 in the figure, a stable main arc is established between the tungsten electrode of the plasma arc welding gun 2 and the workpiece 6;

[0055] Step S4: closing the pilot arc;

[0056] Specifically: Close the maintenance arc ( Figure 2 At the same time, the low ionization energy gas flow control system is turned off to stop the low ionization energy gas supply, and the ion gas flow rate is immediately increased to ensure that the system ion gas flow rate is stable, and a stable main arc is established between the plasma arc welding gun 2 and the workpiece 6.

[0057] Step S5: performing underwater high-pressure dry plasma arc welding.

[0058] Specifically, perform underwater high-pressure dry plasma arc welding. After welding is completed, operate the gas-electric combined control module 4 to execute the arc stop-delayed gas stop program, close the main arc, lag for 10-15 seconds, close the ion gas mixing device, and stop supplying ion gas; open the hatch and check the welding quality.

[0059] In the description of the present invention, it should be noted that, unless otherwise specified, "plurality" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0060] It should also be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention depending on the specific circumstances.

[0061] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An underwater high-pressure plasma arc starting device, characterized in that: The invention comprises a working chamber for providing a high-pressure environment, an ion-gas mixing assembly, and a gas-electricity combined control module. A plasma arc welding gun is provided in the working chamber. The gas-electricity combined control module is controlled and connected to the ion-gas mixing assembly and the plasma arc welding gun. The ion-gas mixing assembly is connected and communicated with the plasma arc welding gun. The ion-gas mixing assembly is used to mix low ionization energy gas and ion gas and deliver the mixed gas to the plasma arc welding gun. The ion-gas mixing assembly is configured as an inverted Y-shaped structure; A low ionization energy gas cylinder and an ion gas cylinder are provided below the ion gas mixing assembly, and the low ionization energy gas cylinder and the ion gas cylinder are connected and communicated with the ion gas mixing assembly; The ion gas mixing assembly is provided with a gas flow controller for controlling the flow rate of the low ionization energy gas and the ion gas, and a high-frequency electromagnetic valve for controlling the start and stop of the low ionization energy gas and the ion gas; The low ionization energy gas includes but is not limited to xenon and carbon monoxide, and the ion gas is argon.

2. The underwater high-pressure plasma arc starting device according to claim 1, characterized in that: The low ionization energy gas is mixed with the ion gas, and the proportion of the low ionization energy gas is 50% to 90%.

3. An underwater high-pressure plasma arc starting method of the underwater high-pressure plasma arc starting device according to claim 1 or 2, characterized in that: The following steps are involved: Step S1: Adjust the low ionization energy gas and ion gas in the mixed gas to the set values ​​and establish a high-pressure environment in the working chamber; Step S2: Operate the gas-electricity combined control module to execute the advance gas supply-pilot arc program; Step S3: Start the main arc switch to establish a stable main arc; Step S4: Close the pilot arc; Step S5: Perform underwater high-pressure dry plasma arc welding.

4. The underwater high-pressure plasma arc starting method according to claim 3, characterized in that: The high-pressure environment pressure value of the working chamber in step S1 is ≥0.15 MPa.

5. The underwater high-pressure plasma arc starting method according to claim 3, characterized in that: The gas supply-arc piloting procedure in step S2 includes opening the low ionization energy gas and ion gas flow control switches, supplying a mixture of the low ionization energy gas and the ion gas, and starting the arc piloting switch after 10 to 15 seconds to establish a stable arc piloting.

6. The underwater high-pressure plasma arc starting method according to claim 3, characterized in that: Closing the pilot arc in step S4 includes closing the low ionization energy gas flow control switch, stopping the low ionization energy gas supply, and immediately increasing the ion gas flow to ensure the stability of the system ion gas flow, and establishing a stable main arc between the plasma arc welding gun and the workpiece.

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