A welding method for ultra-narrow gap

Abstract

The present invention provides an ultra-narrow gap welding device and welding method, which belong to the technical field of ultra-narrow gap welding. The ultra-narrow gap welding device includes an air blowing mechanism, a conductive nozzle, and an industrial chiller. The industrial chiller is connected to the air blowing mechanism, and the industrial chiller flows through the interior of the air blowing mechanism. The industrial chiller is suitable for reducing the temperature of the shielding gas output by the air blowing mechanism and the temperature of the conductive nozzle. The industrial chiller can continuously reduce the temperature of the shielding gas output by the air blowing mechanism and the temperature of the conductive nozzle, so that the temperature of the shielding gas and the conductive nozzle can be kept at a low temperature. The shielding gas in the low temperature state can suppress the ionization of the shielding gas, thereby suppressing the generation of a bypass arc. In addition, this solution does not require the use of a feeding device for other welding materials and auxiliary welding materials, making the welding equipment more concise and eliminating the need to deal with the welding slag generated by the auxiliary welding materials, thereby greatly saving welding time.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-narrow gap welding, and in particular to an ultra-narrow gap welding method. Background Art

[0002] Since arc welding began to be used on a large scale in the industrial manufacturing field in the 1920s, welding grooves must be opened in the structural welding of medium-thick plates, thick plates, large-thick plates, and extra-thick plates, and the arc must be controlled to be located within the welding groove for filling welding.

[0003] To further reduce welding workload, ultra-narrow gap welding technology is employed. Due to the small size of the weld groove, the two side walls of the weld groove must serve as one electrode for the gas-conducting arc. The welding wire, the other electrode (the exposed wire section after the contact tip), is located farther from the bottom of the weld groove than from the two side walls. This results in burning on one side of the groove between the wire and the two side walls, creating arc bypass. Arc bypass results in an unwelded weld at the bottom of the weld groove, resulting in a weld seam at the top and a large void at the bottom. This joint is unable to withstand the working load of the weld joint, resulting in a wasteful weld structure.

[0004] Prior art methods for controlling the arc to prevent arc bypass and burning at the root of the weld groove rely solely on physical insulation. For example, 201110048535.2 describes a device and method for ultra-narrow gap welding with a U-shaped flux band to constrain the arc. This method eliminates arc bypass and arc climbing by physically insulating the exposed wire section after the contact tip is extended from the weld groove, which is very close to the two sides. This physically insulates the weld groove with a non-conductive flux band, forcing the gas discharge (arc burning) between the wire tip and the weld pool to sink to the bottom of the weld groove.

[0005] However, physical insulation leads to the complexity of the arc welding process, and the matching flux belt auxiliary materials must be specially produced. In addition, the welding slag generated by the melting of the flux belt tightly covers the weld surface, which is difficult to remove under the ultra-narrow gap groove. The flux belt conveying mechanism also needs to be added, which increases the complexity of the process equipment. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the defect of the prior art that a bypass arc is easily generated, thereby providing an ultra-narrow gap welding device.

[0007] The present invention provides an ultra-narrow gap welding device, comprising:

[0008] Blowing mechanism, suitable for outputting protective gas;

[0009] A conductive nozzle passes through the gas blowing mechanism; the conductive nozzle extends along the gas flow direction; a welding wire is provided at the end of the conductive nozzle along the gas flow direction; the conductive nozzle is suitable for providing welding current and welding voltage to the welding wire;

[0010] An industrial chiller is connected to the blowing mechanism. The industrial chiller flows through the inside of the blowing mechanism. The industrial chiller is suitable for reducing the temperature of the protective gas output by the blowing mechanism and the temperature of the conductive nozzle.

[0011] As a preferred solution, the ultra-narrow gap welding equipment includes:

[0012] A nozzle structure is connected to the blowing mechanism, and the nozzle structure is sleeved on the outer periphery of the portion of the conductive nozzle extending out of the blowing mechanism, forming a flow channel between the nozzle structure and the conductive nozzle.

[0013] As a preferred solution, the ultra-narrow gap welding equipment further includes:

[0014] A power supply is connected to the blowing mechanism.

[0015] As a preferred solution, the nozzle structure is made of ceramic material.

[0016] As a preferred solution, the industrial chiller uses compressor refrigeration equipment.

[0017] The present invention provides an ultra-narrow gap welding method, which is applied to the ultra-narrow gap welding equipment described above, comprising the following steps:

[0018] Determining that the weld groove is an ultra-narrow gap weld groove based on the weld groove size, and determining the diameter of the welding wire at the end of the conductive tip based on the weld groove size, wherein the diameter of the welding wire is positively correlated with the size of the weld groove gap;

[0019] Adjust the welding current on the welding wire through the conductive nozzle to control the range of the welding current so that the welding wire is within the jet transition range;

[0020] When the welding wire is within the jet transition range, adjusting the welding voltage;

[0021] The air blowing mechanism continuously outputs shielding gas toward the welding groove, and the temperature of the shielding gas output by the air blowing mechanism is continuously reduced by an industrial chiller;

[0022] The welding wire is fed into the welding groove for welding.

[0023] As a preferred solution, the industrial chiller controls the temperature of the protective gas at 10°C-20°C.

[0024] As a preferred solution, the protective gas is a mixed gas of argon and carbon dioxide.

[0025] As a preferred solution, the protective gas is a mixed gas of 80% argon and 20% carbon dioxide.

[0026] As a preferred solution, when the thickness of the workpiece exceeds the length of the welding wire, a nozzle structure is provided on the periphery of the conductive nozzle extending beyond the blowing mechanism portion along the airflow direction.

[0027] The technical solution of the present invention has the following advantages:

[0028] 1. The ultra-narrow gap welding equipment provided by the present invention includes an air blowing mechanism, a conductive nozzle and an industrial chiller. The industrial chiller can continuously reduce the temperature of the shielding gas output by the air blowing mechanism and the temperature of the conductive nozzle, so that the temperature of the shielding gas and the conductive nozzle can be kept at a low temperature. The low-temperature shielding gas can suppress the ionization of the shielding gas, thereby suppressing the generation of a bypass arc. In addition, this solution does not require the use of a feeding device for other welding materials and auxiliary welding materials, making the welding equipment more concise and eliminating the need to deal with the welding slag generated by the auxiliary welding materials, thereby greatly saving welding time.

[0029] 2. The ultra-narrow gap welding equipment provided by the present invention is provided with a nozzle structure. When the welding gap is too deep, the nozzle structure is set on the periphery of the conductive nozzle, and the nozzle structure is set to ceramic material, which can effectively prevent the generation of an arc between the conductive nozzle and the welding gap.

[0030] 3. The ultra-narrow gap welding equipment provided by the present invention, in which the industrial chiller uses a compressor refrigeration equipment, which has the advantages of simple structure and small size, and can achieve a large cooling capacity with lower power consumption, thereby reducing the cost of use.

[0031] 4. The ultra-narrow gap welding method provided by the present invention comprises the following steps: determining an ultra-narrow gap weld groove based on the size of the weld groove; determining the diameter of the welding wire at the end of the conductive nozzle based on the size of the weld groove, wherein the diameter of the welding wire is positively correlated with the size of the weld groove gap; adjusting the welding current on the welding wire through the conductive nozzle to control the welding current range so that the welding wire is within the jet transition range; adjusting the welding voltage when the welding wire is within the jet transition range; continuously outputting shielding gas from the blowing mechanism into the weld groove, and continuously reducing the temperature of the shielding gas output by the blowing mechanism through an industrial chiller; and feeding the welding wire into the weld groove for welding. This solution utilizes an industrial chiller to continuously reduce the temperature of the shielding gas output by the blowing mechanism and the temperature of the conductive nozzle, thereby maintaining the shielding gas and the conductive nozzle at a low temperature. The low temperature shielding gas can suppress ionization of the shielding gas, and by controlling the welding current and welding voltage, the generation of a bypass arc can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are 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.

[0033] Figure 1 This is a schematic diagram of the overall structure of the ultra-narrow gap welding equipment provided by the present invention.

[0034] Figure 2 This is a schematic structural diagram of the nozzle-free structure of the ultra-narrow gap welding equipment provided by the present invention.

[0035] Figure 3 This is a structural schematic diagram of the welding groove in the ultra-narrow gap welding equipment provided by the present invention.

[0036] Description of reference numerals:

[0037] 1. Air blowing mechanism; 2. Conductive nozzle; 3. Industrial chiller; 4. Nozzle structure; 5. Power supply; 6. First welding part; 7. Welding wire; 8. Molten pool; 9. Shielding gas; 10. Second welding part. DETAILED DESCRIPTION

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0040] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0041] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] Example 1

[0043] like Figure 1 As shown, the ultra-narrow gap welding equipment provided by the present invention includes an air blowing mechanism 1, a conductive nozzle 2, and an industrial chiller 3. The air blowing mechanism 1 is adapted to blow out a shielding gas 9. The conductive nozzle 2 passes through the air blowing mechanism 1, and a welding wire 7 is disposed at the end of the conductive nozzle 2 along the airflow direction. The conductive nozzle 2 is adapted to provide welding current and welding voltage to the welding wire 7. The industrial chiller 3 is connected to the air blowing mechanism 1, and the industrial chiller 3 flows through the interior of the air blowing mechanism 1. The industrial chiller 3 is adapted to reduce the temperature of the shielding gas 9 output by the air blowing mechanism 1 and the temperature of the conductive nozzle 2. The industrial chiller 3 continuously reduces the temperature of the shielding gas 9 output by the air blowing mechanism 1 and the temperature of the conductive nozzle 2, thereby maintaining the temperatures of the shielding gas 9 and the conductive nozzle 2 at a constant low temperature. The low temperature of the shielding gas 9 can suppress ionization of the shielding gas 9, thereby suppressing the generation of a bypass arc. Furthermore, this solution eliminates the need for feeding devices for other welding and auxiliary welding materials, making the welding equipment more concise and eliminating the need to deal with the welding slag generated by the auxiliary welding materials, significantly saving welding time.

[0044] It should be noted that the industrial chiller 3 uses a compressor refrigeration device, which has the advantages of simple structure and small size, and can achieve a large cooling capacity with low power consumption, thereby reducing the cost of use. The industrial chiller 3 is specifically provided with a compressor, a power pump, a pipeline and other structures. The pipeline is suitable for being arranged inside the blowing mechanism 1. A heat exchange medium is provided in the pipeline. The power pump causes the heat exchange medium to flow in the heat exchange pipeline and transfers the cooling capacity generated by the compressor to the blowing mechanism 1 through the heat exchange medium. When the protective gas 9 flows through the blowing mechanism 1, it exchanges heat with the blowing mechanism 1, thereby achieving the cooling effect of the industrial chiller 3 on the protective gas 9.

[0045] Furthermore, when the plate thickness of the weldment is large, a nozzle structure 4 needs to be provided. The nozzle structure 4 is connected to the blowing mechanism 1, and the nozzle structure 4 is sleeved on the outer periphery of the portion of the conductive nozzle 2 extending out of the blowing mechanism 1, forming a circulation channel between the nozzle structure 4 and the conductive nozzle 2. The nozzle structure 4 can prevent the conductive nozzle 2 from generating an arc with the side walls on both sides of the welding groove. The shielding gas 9 reaches the welding wire 7 through the circulation channel to protect the welding wire 7. In this solution, the nozzle structure 4 is in the shape of a truncated cone, and the nozzle structure 4 gradually shrinks along the flow direction of the shielding gas 9, and the area of ​​the opening at one end of the nozzle structure 4 is larger than the area of ​​the opening at the other end. The shielding gas 9 enters from one end of the large opening of the nozzle structure 4 and flows out from one end of the small opening. The nozzle structure 4 designed in this way has a convergence effect on the shielding gas 9 and increases the effective protection range of the shielding gas 9.

[0046] It should be noted that, generally, the nozzle structure 4 needs to be used when the thickness of the weldment is greater than 16 mm.

[0047] It should be noted that the nozzle structure 4 is made of ceramic in this embodiment. As an alternative embodiment, insulating materials such as plastic and rubber may also be used.

[0048] Furthermore, the ultra-narrow gap welding equipment also includes a power supply 5 connected to the air blowing mechanism 1. The power supply 5 can provide energy to the air blowing mechanism 1, the contact nozzle 2, the industrial chiller 3, and other equipment. The power supply 5 is generally located on one side of the air blowing mechanism 1.

[0049] Example 2

[0050] like Figure 2As shown, the ultra-narrow gap welding method provided in this embodiment uses the welding equipment in Example 1 and also includes the following steps: judging the welding groove as an ultra-narrow gap welding groove according to the size of the welding groove, determining the diameter of the welding wire 7 at the end of the conductive nozzle 2 according to the size of the welding groove, and the diameter of the welding wire 7 is positively correlated with the size of the groove gap; adjusting the welding current on the welding wire 7 through the conductive nozzle 2, and controlling the range of the welding current to make the welding wire 7 within the jet transition range; when the welding wire 7 is within the jet transition range, adjusting the welding voltage; the blowing mechanism 1 continuously outputs the shielding gas 9 toward the welding groove, and continuously reduces the temperature of the shielding gas 9 output by the blowing mechanism 1 through the industrial chiller 3; and feeding the welding wire 7 into the welding groove for welding. This solution can continuously reduce the temperature of the shielding gas 9 output by the blowing mechanism 1 and the temperature of the conductive nozzle 2 through the industrial chiller 3, so that the temperature of the shielding gas 9 and the conductive nozzle 2 can always be maintained at a low temperature. The shielding gas 9 in the low temperature state can suppress the ionization phenomenon of the shielding gas 9, and by controlling the size of the welding current and the size of the welding voltage, the generation of the bypass arc can be suppressed.

[0051] like Figure 3 As shown, it should be noted that the ultra-narrow gap welding groove is designed to have an extremely small groove face angle. The ultra-narrow gap welding groove with an extremely small groove face angle means that the minimum assembly gap at the root is in the ultra-narrow gap range, and the grooves of the two side walls are not in a vertical state (0°), but in an inclined state with an extremely small groove face angle; the size of the groove face angle varies inversely with the plate thickness of the weldment, that is, when the plate thickness is smaller, the groove face angle is larger, and when the plate thickness is larger, the groove face angle is smaller; the extremely small groove face angle range is 0.5°-4°; the maximum value of the minimum assembly gap at the root is 6mm.

[0052] In this embodiment, the angle of the groove face angle is β, the minimum assembly gap at the root is b, the plate thickness of the weldment is T, and the size of the groove face angle β varies inversely with the plate thickness T of the weldment, that is, when the plate thickness T of the weldment is smaller, the groove face angle β is larger, and when the plate thickness T of the weldment is larger, the groove face angle β is smaller; the minimum group groove face angle range is 2°~4°, the groove face angle β of the first weldment and the second weldment is 0.5°~3°, in this example, the plate thickness T of the weldment is 300mm, β is 0.5°, and the minimum assembly gap b at the root is 5 mm.

[0053] In this example, the plate thickness T is greater than 16 mm, so a nozzle structure 4 is required. The nozzle structure 4 is used to insulate the weldment from the contact nozzle 2.

[0054] It should be noted that the welding wire 7 is burned and fused at the bottom of the welding groove, and this area becomes a molten pool 8.

[0055] It should be noted that, in this embodiment, the welding wire 7 is a solid welding wire 7, and the diameter of the welding wire 7 is in the range of 0.8 mm to 1.2 mm. Specifically, in this embodiment, the diameter of the welding wire 7 is 1.2 mm.

[0056] It should be noted that, under a given diameter of the welding wire 7, the welding current is one of the important parameters of the arc energy characteristics. The selection range of the welding current is medium to lower medium in the jet transition specification zone corresponding to the welding wire 7. When the diameter of the welding wire 7 is 1.2 mm, the welding current range is 220A-270A.

[0057] The arc length (arc length for short) also needs to be controlled, which means controlling the welding voltage. Keep the welding voltage in the middle or upper middle range of the arc voltage that matches the jet transition current to avoid excessive arc divergence, and thus an increased cathode conductive zone diameter. For welding currents between 220A and 270A, the welding voltage range is 23V to 28V.

[0058] Arc stiffness (stiffness) also needs to be controlled. Arc stiffness is positively correlated with arc force. As the most important components of arc force, electromagnetic contraction force and plasma flow force are both positively correlated with current intensity. Therefore, arc stiffness is adjusted to a medium-high level to increase the radial compression of the arc by the magnetic field and prevent radial expansion. The type and flow rate of gas also affect arc stiffness to a certain extent. The present invention uses a very low primary shielding gas flow rate and selects a polyatomic gas with low dissociation energy (such as a certain proportion of CO2), both of which are beneficial for preventing arc bypass. Shielding gas 9 is a mixture of argon and carbon dioxide.

[0059] It should be noted that, in this embodiment, the flow rate of the shielding gas 9 is 8 L / min to 10 L / min, and the shielding gas 9 is specifically 80% argon + 20% carbon dioxide.

[0060] It should be noted that the bypass arc occurs in the section of the welding wire 7 extending out of the conductive nozzle 2. Controlling the preheating temperature of this section of the welding wire 7 at a very low state will help suppress the ionization of the protective gas 9 around the welding wire 7, thereby suppressing the generation of the bypass arc.

[0061] It should be noted that in this embodiment, not only does the industrial chiller 3 provide very low and constant temperature cooling circulating water to efficiently cool the contact tip 2 and the wire guide tube in the welding gun body, keeping them at a consistently low temperature, but it also requires controlling the current connection point on the electrode, the welding wire 7, to minimize the current path through the wire 7. In this embodiment, the industrial chiller 3 controls the temperature of the shielding gas 9 at 10°C-20°C. The anode current flows only about 20 mm along the welding wire 7.

[0062] Example 3

[0063] This embodiment is an alternative to Example 2. In this embodiment, the weldment thickness T is 20 mm, the minimum assembly groove angle 2β is 4°, the groove angle β between the first and second weldments is 2°, and the minimum root assembly gap b is 4.5 mm. The diameter of the welding wire 7 in this embodiment is 1.0 mm.

[0064] The remaining parameters and steps are the same as those in Example 2.

[0065] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for ultra-narrow gap welding, characterized in that: The following steps are involved: Ultra-narrow gap welding grooves have a minimum groove face angle: Based on the size of the welding groove, it is judged to be an ultra-narrow gap welding groove. The minimum groove face angle of the ultra-narrow gap welding groove is in the range of 0.5° to 4°, and the minimum assembly gap at the root of the groove does not exceed 6mm; Selecting welding wire (7): determining the diameter of the welding wire (7) at the end of the conductive nozzle (2) according to the size of the welding groove, the diameter of the welding wire (7) is positively correlated with the size of the groove gap, and the diameter of the welding wire (7) is: 0.8mm to 1.2mm; The distance that the anode current flows through the welding wire (7) is: 20 mm; Controlling the welding current within the jet transition range: adjusting the welding current on the welding wire (7) through the conductive nozzle (2), controlling the welding current range so that the welding wire (7) is within the jet transition range, and the welding current range is 220A-270A; The welding voltage is controlled when the welding wire (7) is within the jet transition range: when the welding wire (7) is within the jet transition range, the welding voltage is adjusted to 23V-28V; Continuously outputting a shielding gas (9) toward the welding groove through the blowing mechanism (1), wherein the flow rate of the shielding gas (9) is 8 L / min to 10 L / min; Controlling the preheating temperature of the welding wire (7): continuously reducing the temperature of the shielding gas (9) outputted by the blowing mechanism (1) by an industrial water chiller (3), and controlling the temperature of the shielding gas (9) to be between 10°C and 20°C, wherein the industrial water chiller (3) is a compressor refrigeration device; Feeding the welding wire (7) into the welding groove for welding; When the thickness of the weldment exceeds 16 mm, a nozzle structure (4) is sleeved on the outer periphery of the conductive nozzle (2) extending out of the blowing mechanism (1) along the airflow direction, and the nozzle structure (4) is made of insulating material.

2. The ultra-narrow gap welding method according to claim 1, characterized in that: The protective gas (9) is a mixed gas of argon and carbon dioxide.

3. The ultra-narrow gap welding method according to claim 1, characterized in that: The protective gas (9) is a mixed gas of 80% argon and 20% carbon dioxide.

4. The ultra-narrow gap welding method according to claim 1, characterized in that: The conductive nozzle (2) is extended along the gas flow direction, and a welding wire (7) is provided at the end of the conductive nozzle (2) along the gas flow direction.

5. The ultra-narrow gap welding method according to claim 1, characterized in that: The nozzle structure (4) is connected to the blowing mechanism (1), and the nozzle structure (4) is sleeved on the outer periphery of the portion of the conductive nozzle (2) extending out of the blowing mechanism (1), forming a flow channel between the nozzle structure (4) and the conductive nozzle (2).

6. The ultra-narrow gap welding method according to claim 1, characterized in that: The nozzle structure (4) is made of ceramic material.

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