A method and system for controlling a welding wire droplet

Abstract

The application belongs to the technical field of welding, and discloses a welding wire droplet control method and system. A hollow air curtain formed by a first gas generates a thrust on the droplet, so that the droplet smoothly separates from the welding wire, moves along the direction of the first gas to the welding piece, spreads and wets in the welding area, fills the weld and completes welding, so that the droplet smoothly falls off from the welding wire, moves to the welding piece, and is kept in the welding area, enters the weld and completes the welding work.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding technology, in particular to a welding wire droplet control method and system. BACKGROUND

[0002] Welding, also known as fusion welding, is a manufacturing process and technology that joins metals or other thermoplastic materials such as plastics by heating, high temperature or high pressure. For some welding scenarios, due to the welding wire material, welding environment, welding parameters and other reasons, the molten droplet produced after the welding wire melts cannot be smoothly separated from the welding wire, thereby affecting the welding efficiency and welding quality, especially in the weightless environment, such as on-site welding in space, which faces great challenges. In the weightless environment, there is no earth gravity, the molten droplet produced by the welding wire melting will be suspended at the end of the welding wire under the action of surface tension, forming a spherical droplet floating in the air, which cannot fall onto the welding part to complete the molten pool flow and solidification process, thereby failing to fill the gap between the welds to form a complete and defect-free weld, and thus failing to complete the welding work. SUMMARY

[0003] In order to solve the problem that the molten droplet cannot be smoothly separated from the welding wire in the prior art to complete the welding, the present application provides a welding wire droplet control method and system, so that the molten droplet is smoothly separated from the welding wire, moves towards the welding part, and remains in the welding area to enter the weld and complete the welding work.

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme.

[0005] Firstly, on the one hand, the present application provides a welding wire droplet control method, which comprises: turning on a first gas, the first gas forming a hollow air curtain vertically blowing towards the welding area of the welding part; turning on a welding device, a heat source at the cathode end of the welding torch acting on the end of the welding wire, the end of the welding wire being located in the hollow air curtain; the end of the welding wire generating a molten droplet under the action of the heat source, the molten droplet continuously growing; when the diameter of the molten droplet exceeds a preset diameter, the molten droplet is subjected to the force of the first gas and gradually separates from the welding wire, moving towards the welding area; the molten droplet reaches the welding area of the welding part and extends and fills the weld under the action of the first gas; cooling, completing the welding.

[0006] Further, the end of the welding wire is located at the center of the hollow air curtain, so that the molten droplet generated by the welding wire is located at the center of the hollow air curtain, and the preset diameter is equal to the inner diameter of the cross section of the hollow air curtain.

[0007] Further, the method further comprises: when the diameter of the droplet exceeds the preset diameter, the second gas is opened, the second gas is blown to the droplet from the center of the first gas in a direction perpendicular to the welding area, the droplet is separated from the welding wire under the action of the first gas and the second gas, and moves to the welding area; the second gas is intermittently opened, and the duration is less than 5s.

[0008] Further, the second gas is intermittently opened, which comprises: when the second gas is opened for the first time, the control system starts timing; the control system opens the second gas every preset time T, and in the preset time T, the droplet generated last time on the welding wire is separated from the welding wire and the newly generated droplet grows to a diameter exceeding the preset diameter.

[0009] Further, the method further comprises: the cathode side of the welding torch is provided with a ring array designed shielding sensor, forming a shielding monitoring area, when the diameter of the droplet exceeds the edge of the shielding monitoring area, the shielding sensor sends a signal to the control center, the control center controls the opening of the second gas, the diameter of the shielding monitoring area is less than or equal to the diameter of the hollow air curtain; when the droplet is separated from and gradually away from the welding wire, and the distance between the droplet and the welding wire exceeds the monitoring range of the shielding sensor, the shielding sensor restores and sends control information to the control center, and the control center closes the second gas; the shielding sensor is one or more of an inductive proximity switch, a capacitive proximity switch, an ultrasonic sensor, a laser ranging sensor and a millimeter wave radar.

[0010] On the other hand, the present application also provides a welding wire droplet control system for realizing the above-mentioned method, the control system comprising a welding device, a first gas blowing device, a wire feeding device and a control center, the welding device comprising a welding torch and a power supply, the first gas blowing device comprising a first gas jet, a first gas channel, a first gas driving device and a first gas source, the first gas jet being connected to the first gas driving device through the first gas channel, the first gas driving device being connected to the control center and the first gas source, the opening and closing of the first gas being realized under the control of the control center, the first gas jet forming a hollow air curtain and being blown vertically to the welding area of the welding piece, the wire feeding device being used for continuous wire feeding and keeping the end of the welding wire in the hollow air curtain.

[0011] Further, the above-mentioned system further comprises a second gas blowing device, the second gas blowing device comprising a second gas jet, a second gas channel, a second gas driving device and a second gas source, the second gas jet being located inside the ring formed by the first gas jet, and the second gas jet being connected to the second gas driving device through the second gas channel, the second gas driving device being connected to the control center and the second gas source, the opening and closing of the second gas being realized under the control of the control center.

[0012] Further, the welding device is a laser-hollow tungsten electrode coaxial composite welding device, the first gas outlet is designed around the hollow tungsten electrode, and the second gas outlet is arranged at the center of the hollow tungsten electrode.

[0013] Further, the first gas passage and / or the first gas outlet are multiple, arranged in a ring shape in sequence along the side of the hollow tungsten electrode, or the first gas passage and / or the first gas outlet are an integral ring structure arranged around the hollow tungsten electrode.

[0014] Further, the side of the hollow tungsten electrode is provided with a shielding sensor, and the shielding sensor is one or more of an inductive proximity switch, a capacitive proximity switch, an ultrasonic sensor, a laser ranging sensor and a millimeter wave radar.

[0015] The beneficial effects of the present application are:

[0016] The hollow air curtain formed by the first gas generates a thrust on the droplet, so that the droplet smoothly separates from the welding wire, moves along the direction of the first gas to the welding piece, spreads and wets in the welding area, fills the weld and completes welding, so that the droplet smoothly falls off from the welding wire, moves to the welding piece, enters the weld in the welding area and completes the welding work; in addition, the welding torch structure is improved, the gas ejection device is integrated in the welding torch, the system structure is simplified, and the intelligent control of the droplet falling and movement is realized through time interval control, shielding sensor sensing and other technologies, and the welding efficiency and welding quality are further improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are included to provide a further understanding of the present application and constitute a part of this application, illustrate certain illustrative embodiments of the present application and together with the description serve to explain the present application. In the drawings:

[0018] Figure 1 is a structural schematic diagram of the control system of an embodiment of the present application;

[0019] Figure 2 is another structural schematic diagram of the control system of an embodiment of the present application;

[0020] Figure 3 is a structural schematic diagram of a stand-alone first gas passage of the control system of an embodiment of the present application;

[0021] Figure 4 is a structural schematic diagram of a stand-alone first gas passage of the control system of an embodiment of the present application;

[0022] Figure 5 is a structural schematic diagram of a cylindrical air curtain of an embodiment of the present application;

[0023] Figure 6 is a schematic flow diagram of the welding wire droplet control method of an embodiment of the present application;

[0024] Figure 7 is another schematic structural diagram of the control system of an embodiment of the present application;

[0025] Figure 8 is another schematic structural diagram of the control system of an embodiment of the present application;

[0026] Figure 9 is a schematic diagram of droplet variation of an embodiment of the present application;

[0027] Figure 10 is a schematic diagram of the shielding sensor arrangement of an embodiment of the present application;

[0028] Figure 11 is a bottom view of the welding torch structure in which the shielding sensor is arranged of an embodiment of the present application.

[0029] In the figure, 1 is a welding torch, 101 is a hollow tungsten electrode, 102 is a ceramic nozzle, 103 is a welding torch shell, 2 is a first gas jet, 3 is a first gas channel, 4 is a first gas driving device, 5 is a first gas source, 6 is a control center, 7 is a welding piece, 8 is a droplet, 801 is a small droplet, 802 is a large droplet, 8021 is a large droplet about to break away, 8022 is a moving large droplet, 8023 is a large droplet reaching the welding area, 8024 is a large droplet in deformation and spreading, 9 is a first gas, 10 is a laser, 11 is a welding wire, 12 is a cylindrical gas curtain, 13 is a second gas, 14 is a second gas driving device, 15 is a second gas source, and 16 is a shielding sensor. DETAILED DESCRIPTION

[0030] In the description of the present application, the following terms need to be explained:

[0031] For the terms of orientation, the specification and claims of the present application have terms such as "center", "transverse", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicating the orientation and positional relationship are based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and cannot be understood as limiting the specific protection scope of the present application.

[0032] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0033] The terms "comprise" and "have" and any variations thereof in the specification and claims of this application are intended to cover a process, method, system, product, or apparatus that comprises a series of steps or units without necessarily being limited to only those steps or units clearly recited. Such terms are also intended to cover a process, method, system, product, or apparatus that comprises additional steps or units that are not expressly recited in the specification and claims.

[0034] When an element is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements can be present. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or intervening elements can be present. When an element is referred to as "comprising" another element, it can be present on the surface or inside the element.

[0035] Unless otherwise defined, the terms "comprise" or variations such as "comprises" or "comprising" in the specification and claims of this application will be understood to encompass the elements or components recited in the specification and claims, without excluding other elements or components.

[0036] In the specification and claims of this application, the term "electrically connected" can refer to a circuit connection that can be in physical contact or a communication connection, which can be a wired communication connection or a wireless communication connection.

[0037] In order to make the objectives, technical solutions, and advantages of the present application clearer, further detailed descriptions will be given below in conjunction with embodiments or specific implementation manners and the accompanying drawings. The illustrative embodiments of the present application and their descriptions are only used to explain the present application and do not limit the present application.

[0038] It should be noted that the embodiments or implementation manners described below or the technical features thereof can be combined with each other or combined with other technical features to form new embodiments, which also belong to the scope of protection of the present application.

[0039] First, in one embodiment, a welding wire droplet control system is provided, such as Figure 1As shown, the control system includes a welding device, a first gas blowing device, a wire feeding device, and a control center 6. The welding device includes a welding torch 1 and a power source. The first gas blowing device includes a first gas blowing port 2, a first gas channel 3, a first gas driving device 4, and a first gas source 5. The first gas blowing port 2 is connected to the first gas driving device 4 through the first gas channel 3. The first gas driving device 4 is connected to the control center 6 and the first gas source 5. The opening and closing of the first gas 9 are realized under the control of the control center 6. The first gas 9 blown by the first gas blowing port 2 forms a hollow air curtain, which is blown vertically to the welding area of the welding piece 7. The wire feeding device is used to continuously feed the wire 11 and keep the end of the wire 11 in the hollow air curtain. Optionally, the above-mentioned first gas blowing device can be separately arranged outside the welding device, for example, Figure 1 An actual layout mode is shown. A support is designed above the welding area of the welding piece 7 to fix the first gas blowing device. The installation position and precision of the first gas blowing device should be coordinated with the welding device, the welding area, the wire feeding device, and the like, so that the heat source of the welding device can hit the end of the wire 11, and the end of the wire 11 and the welding area can be located in the hollow air curtain formed by the first gas 9. For example, Figure 1 As shown. The welding device used can be aluminum alloy MIG welding, aluminum alloy TIG welding, titanium alloy TIG welding, high-strength steel MAG welding, laser-arc composite welding, laser-hollow tungsten electrode arc coaxial composite welding, and the like. In some embodiments, laser-hollow tungsten electrode arc coaxial composite welding is used. The laser 10 and the electric arc double heat sources act on the end of the wire 11 at the same time to improve the welding efficiency, as shown in Figure 2 As shown, the upper part of the hollow tungsten electrode 101 is connected with a ceramic nozzle 102, and the outer side of the hollow tungsten electrode 101 is a welding torch shell 103. The shape of the hollow air curtain formed by the first gas 9 can also be designed into other shapes, such as a circular shape, a square shape, an oval shape, a triangular shape, and the like according to the welding requirements in the specific design. As long as the overall thrust can be applied to the spherical large droplet 802 to blow it away from the wire 11 and to the welding piece 7 to complete the welding, the following is described by taking the circular shape as an example, that is, the hollow air curtain formed by the first gas 9 is a hollow cylindrical air curtain 12.

[0040] During welding, the heat source of the welding device heats the wire 11, so that the end of the wire 11 generates a droplet 8. In the weightless environment, especially in outer space, the droplet generates without gravity, and if there is no other external force, the droplet 8 will always stay at the end of the wire 11 and continue to be heated by the heat source. More and more wire 11 is melted, and the droplet 8 is longer and larger, and cannot drop onto the welding piece 7 to complete the welding. The above-mentioned system is used to control the droplet 8 of the wire 11, and the welding in the weightless condition is successfully realized. Specifically, the control method of the droplet is as shown in Figure 6 As shown, the control method of the droplet includes the following steps.

[0041] S1: open the first gas 9, the first gas 9 forms a hollow cylindrical gas curtain 12, which blows vertically to the welding area of the welding piece 7;

[0042] S2: open the welding device, the heat source of the cathode end of the welding torch 1 acts on the end of the welding wire 11, and the end of the welding wire 11 is located in the cylindrical gas curtain 12;

[0043] S3: the end of the welding wire 11 generates a droplet 8 under the action of the heat source, and the droplet 8 grows continuously;

[0044] S4: when the diameter of the droplet 8 exceeds the preset diameter, the droplet 8 is subjected to the force of the first gas 9 and gradually separates from the welding wire 11 and moves to the welding area;

[0045] S5: the droplet 8 reaches the welding area of the welding piece 7 and spreads and fills the weld under the action of the first gas 9;

[0046] S6: cooling, completing the welding.

[0047] In the above method, during actual welding, steps S1, S2 and step S3 do not have to follow the above sequence, especially step S1 can be after step S2 and / or step S3, as long as the droplet 8 is not grown to a diameter exceeding the preset diameter. In a weightless environment, especially in outer space, the droplet 8 will stay at the end of the welding wire 11 after being generated without gravity, and will condense into a spherical droplet 8 under the action of surface tension. When the droplet 8 grows to a certain extent, part or all of the edges of the droplet 8 exceed the range of the cylindrical gas curtain 12, blocking the first gas 9 forming the cylindrical gas curtain 12, the first gas 9 generates a pushing force on the droplet 8, making the droplet 8 gradually separate from the welding wire 11 and move to the welding piece 7 along the direction of the first gas 9. Since the first gas 9 is continuous, the droplet 8 reaches the welding area and is continuously flattened under the pressure of the first gas 9 and the welding piece 7, and then spreads, wets and enters the weld for filling. When the welding requirement is met, the welding is completed after timely cooling.

[0048] Optionally, the first gas passage 3 and / or the first gas jet 2 can be a continuous whole annular structure, such as Figure 1 and Figure 2, are integral annular structures, for example, the first gas channel 3 is a hollow shell in the shape of an inverted U surrounding the cathode of the welding torch 1, the opening at the bottom of the inverted U shape becomes the first gas jet 2, and the bottom of the inverted U shape is connected to the first gas driving device 4 through a gas pipeline. The first gas 9 enters the bottom of the inverted U shape through the first gas driving device 4 and the gas pipeline, and then flows outward from the center to the periphery, and further enters the space on the side of the inverted U shape, and is sprayed out from the first gas jet 2 at the bottom of the inverted U shape. Since in a weightless environment such as space, the droplet 8 will generally tend to converge into a spherical droplet without other external forces, therefore, the first gas channel 3 or the first gas jet 2 is designed to be annular in this embodiment, which is also based on this reason, so that the sprayed first gas 9 forms a hollow cylindrical gas curtain 12.

[0049] The first gas channel 3 and / or the first gas jet 2 described above are integral annular gas channels or annular gas jets. Such a structure is simple and easy to clean. In order to save costs, in some embodiments, the first gas channel 3 and / or the first gas jet 2 can also be a plurality of first gas channels 3 and / or a plurality of first gas jets 2 arranged independently and centrally, that is, independent first gas channels 3 and / or first gas jets 2. The plurality of first gas channels 3 and / or the plurality of first gas jets 2 can be arranged in sequence along the circumferential direction, that is, the plurality of first gas channels 3 are arranged in sequence in the same annular space, or the plurality of first gas jets 2 are arranged in sequence below the same annular space, so that the sprayed first gas 9 forms a cylindrical gas curtain 12 similar to the above, forming a hollow cylindrical shape. Optionally, the specific structure of the first gas channel 3 and / or the first gas jet 2 can be that one first gas channel 3 corresponds to one first gas jet 2, and the opening at the lower end of the first gas channel 3 is the first gas jet 2, as shown in Figure 3 and Figure 4 Each first gas channel 3 and / or each first gas jet 2 can be independently connected to its own first gas driving device 4, and the flow rate and volume of gas of each first gas channel 3 and / or each first gas jet 2 can be independently controlled through the respective first gas driving device 4, and even directly controlled to blow gas or turn off the gas, so as to control the movement direction and path of the droplet 8, and at the same time, the shape of the droplet 8 can also be controlled after the droplet 8 reaches the welding area of the welding piece 7 in this way, and the droplet 8 can be controlled to move in a predetermined direction along a predetermined path, greatly improving the controllability and welding quality. Each first gas driving device 4 can be connected to the same first gas source 5, or can be independently connected to different first gas sources 5. Optionally, the specific structure of the first gas channel 3 and / or the first gas jet 2 can also be that one first gas channel 3 corresponds to a plurality of first gas jets 2, that is, the bottom of the integral first gas channel 3 is opened as a plurality of first gas jets 2, or a plurality of first gas channels 3 correspond to one first gas jet 2, that is, a plurality of first gas channels 3 finally pass through one integral first gas jet 2 as an outlet, which can be flexibly designed according to actual needs.

[0050] In the above scheme, a portion or all of the edge of the droplet 8 exceeds the range of the cylindrical gas curtain 12 and is blown away from the welding wire 11 by the first gas 9. If the droplet 8 is not in the center of the cylindrical gas curtain 12, as the droplet 8 grows, a portion of the edge of the droplet 8 exceeds the range of the cylindrical gas curtain 12 and is subjected to the force of the first gas 9. At this time, the preset diameter can be a value artificially designed according to welding requirements. If the droplet 8 is in the center of the cylindrical gas curtain 12, when the droplet 8 grows to a diameter exceeding the inner diameter of the cross section of the cylindrical gas curtain 12, the droplet 8 is subjected to the force of the first gas 9 and is blown away from the welding wire 11. Therefore, in some embodiments, the end of the welding wire 11 is located in the center of the cylindrical gas curtain 12, so that the droplet 8 generated by the welding wire 11 is located in the center of the cylindrical gas curtain 12, and the preset diameter is equal to the inner diameter of the cross section of the cylindrical gas curtain 12. In this way, the droplet 8 can be automatically controlled. During the process of the welding wire 11 slowly melting to generate a droplet 8 and slowly growing, because the volume of the droplet 8 is small enough to be located in the cylindrical gas curtain 12 formed by the first gas 9 and not to touch the first gas 9, as the welding wire 11 continues to melt, the droplet 8 slowly grows and grows to a diameter exceeding the inner diameter of the cross section of the cylindrical gas curtain 12, and is subjected to the force of the first gas 9 and is blown away from the welding wire 11. On the one hand, the welding wire 11 continues to melt to generate a new droplet 8 under the action of the heat source. The new droplet 8 slowly grows and coalesces into a small droplet 801 in the cylindrical gas curtain 12 without any external force other than surface tension, and gradually becomes a new large droplet 802, which is then blown off by the first gas 9. On the other hand, because the first gas 9 is continuous, after the above-mentioned large droplet 802 is separated from the welding wire 11, it continues to be subjected to the pushing force of the first gas 9 and moves towards the welding part 7 and reaches the welding area. Under the extrusion of the first gas 9 and the welding part 7 on both sides, the large droplet 802 is continuously flattened and then spreads, wets, and enters the weld to fill the weld. In this way, the welding wire 11 continuously generates new droplets 8, which grow in the cylindrical gas curtain 12, gradually change from small droplets 801 to large droplets 802, and are then blown off by the cylindrical gas curtain 12 formed by the first gas 9 to reach the welding part 7 to spread, wet, and fill the weld. This process continues to ensure the smooth progress of welding. For details, please refer to Figure 5 When the welding continues and cools down in time after reaching the welding requirements, the first gas 9 is turned off, and the welding is completed.

[0051] Optionally, in an embodiment, the control system further comprises a second gas jetting device, which comprises a second jetting port, a second gas channel, a second gas driving device 14 and a second gas source 15, the second jetting port is located inside the annular formed by the first jetting port 2, and the second jetting port is connected to the second gas driving device 14 through the second gas channel, the second gas driving device 14 is connected to the control center 6 and the second gas source 15, and the opening and closing of the second gas 13 is realized under the control of the control center 6. Like the first gas jetting device, the second gas jetting device can also be arranged independently of the welding device or integrated with the welding device. In some embodiments, a bracket is designed above the welding area of the welding piece 7 to fix the second gas jetting device, and the installation position and precision of the second gas jetting device should be matched with the first gas jetting device, so that the second gas 13 can pass through the cylindrical gas curtain 12 formed by the first gas 9 to exert a pushing force on the droplet 8, as shown in Figure 7 .

[0052] In other embodiments, laser-hollow tungsten electrode arc coaxial composite welding is adopted, the end of the welding wire 11 is acted on by the laser 10 and the electric arc double heat sources at the same time to improve the welding efficiency, and the first gas 9 and the second gas 13 are integrated in the welding torch 1 of the laser-hollow tungsten electrode arc coaxial composite welding, as shown in Figure 8 , the first jetting port 2 is designed around the cathode of the welding torch 1, and the second jetting port is arranged at the center of the hollow tungsten electrode 101. The first gas channel 3 and / or the first jetting port 2 are multiple, arranged in a ring along the side of the hollow tungsten electrode 101, or the first gas channel 3 and / or the first jetting port 2 are integral annular structures arranged around the hollow tungsten electrode 101. This structure arranges the first gas channel 3 and the first jetting port 2 around the hollow tungsten electrode 101, and ingeniously utilizes the hollow structure of the hollow tungsten electrode 101, arranges the second jetting port at the center of the hollow tungsten electrode 101, so that the second gas 13 is directly jetted from the center of the hollow tungsten electrode 101, and at the same time, the second gas 13 can be well ensured to be located inside the cylindrical gas curtain 12 formed by the first gas 9 and at the central position, which is more conducive to the balance of the pushing force of the gas on the droplet 8 and the stability of the welding performance.

[0053] Correspondingly, compared with the droplet control method of the above scheme, step S4 further comprises:

[0054] S401: when the diameter of the droplet 8 exceeds the preset diameter, the second gas 13 is opened, and the second gas 13 is blown to the droplet 8 from the center of the first gas 9 in a direction perpendicular to the welding area,

[0055] S402: The droplet 8 is separated from the welding wire 11 under the action of the first gas 9 and the second gas 13, and moves to the welding area; the second gas 13 is intermittently opened, and the duration is less than 5s.

[0056] In the above scheme, the first gas channel 3 and the first gas jet 2 are designed to be spaced around the hollow tungsten electrode, forming a ring around the hollow tungsten electrode, and the second gas jet is arranged at the center of the hollow tungsten electrode 101, so that the second gas 13 is blown out from the center of the hollow tungsten electrode and is located in the same space as the laser 10. Below the hollow tungsten electrode 101, the end of the welding wire 11 is located at the center of the cylindrical gas curtain 12 formed by the first gas 9. When the welding wire 11 slowly melts to produce a small droplet 801, the small droplet 801 is only affected by surface tension in the weightless environment and slowly gathers into a spherical shape. The center of the spherical droplet 8 is located on the axis of the hollow tungsten electrode 101 at this time, and also on the axis of the cylindrical gas curtain 12 formed by the first gas 9. Since the volume of the droplet 8 is small enough, it is located in the cylindrical gas curtain 12 formed by the first gas 9 and will not touch the first gas 9. As the welding wire 11 continues to melt, the small droplet 801 slowly grows, and when it grows to a large droplet 802 with a diameter larger than the inner diameter of the cross section of the cylindrical gas curtain 12, it will be affected by the force of the first gas 9. The first gas 9 forms a ring-shaped action surface on the large droplet 802. At this time, the second gas 13 is opened, and the second gas 13 is blown out from the center of the hollow tungsten electrode 101. The center of the large droplet 802 is also located on the central axis of the second gas 13. Therefore, the second gas 13 can exert a central thrust on the large droplet 802, so that the large droplet 802 is gradually blown away from the welding wire 11 under the action of the outer peripheral action of the first gas 9 and the central thrust of the second gas 13, and successively experiences different states such as the large droplet 8021 about to be separated, the large droplet 8022 in movement, the large droplet 8023 reaching the welding area, and the large droplet 8024 in deformation and spreading, and completes the welding process from the welding wire 11 to the weld. For details, please refer to Figure 9The welding wire 11 continues to melt under the action of the heat source to generate new droplets 8. The new droplets 8 are not subjected to any external force other than surface tension inside the cylindrical gas curtain 12, and slowly grow and coalesce into a spherical shape. In this process, the first gas 9 continuously pushes the previous large droplet 802 to the welding area of the welding part 7, and on the other hand, the first gas 9 also forms a protective space for the newly formed small droplet 801 to prevent external forces from affecting the small droplet 801. The small droplet 801 slowly grows into a new large droplet 802 inside the cylindrical gas curtain 12, and then is blown off by the first gas 9. On the other hand, since the first gas 9 is continuous, the above-mentioned large droplet 802 will continue to be subjected to the pushing force of the first gas 9 after it is separated from the welding wire 11, and will move towards the welding part 7 and reach the welding area. Under the extrusion of the first gas 9 and the welding part 7 on both sides, the large droplet 802 is continuously flattened, and then spreads, wets, and enters the weld to fill the weld. In this way, the welding wire 11 continuously generates new droplets 8, which grow in the cylindrical gas curtain 12, and then are blown off by the first gas 9 to reach the welding part 7 to spread, wet, and fill the weld. This continues to ensure the smooth progress of the welding. When the welding requirement is reached, the first gas 9 is turned off in time, and the welding is completed.

[0057] It should be noted that the second gas 13 is intermittently opened, and when the droplet 8 grows to a diameter exceeding a preset diameter, for example, part or all of the edge of the droplet 8 exceeds the cylindrical gas curtain 12 formed by the first gas 9, at this time, the droplet 8 will contact the continuously opened first gas 9, and the first gas 9 will form an annular acting surface and force on the droplet 8, pushing the droplet 8 to fall off from the welding wire 11, but due to the position difference of the droplet 8, especially when the droplet 8 deviates from the center of the cylindrical gas curtain 12, the cylindrical gas curtain 12 cannot accurately align the center of the droplet 8, at this time, only part of the edge of the droplet 8 contacts the first gas 9, which is a local force applied to the droplet 8 by the first gas 9, which will cause the droplet 8 to be partially torn or turned upside down, which is not conducive to the shape of the droplet 8 to remain and move as a whole. Therefore, at this time, the second gas 13 needs to be applied from the inside of the cylindrical gas curtain 12 formed by the first gas 9 to the droplet 8 to apply an additional pushing force, so that the droplet 8 falls off from the welding wire 11 more quickly, and the acting point of the second gas 13 is closer to the center of the droplet 8, which can overcome the above-mentioned disadvantages caused by the local force of the first gas 9 on the droplet 8 to some extent, so that the droplet 8 falls off from the welding wire 11 more quickly and stably, and remains spherical. However, after the large droplet 802 falls off from the welding wire 11, the welding wire 11 will continue to melt and generate a new droplet 8, and if the second gas 13 is continuously opened, the newly generated droplet 8 will be blown away by the second gas 13 before it has a chance to grow, and will become small liquid beads floating in the air, so that the welding cannot continue. Therefore, only when the large droplet 802 needs to fall off from the welding wire 11 after growing, the second gas 13 is used to apply an additional pushing force, and the second gas 13 should be stopped after the large droplet 802 falls off from the welding wire 11. Therefore, the second gas 13 is intermittently opened, and the opening time should not be too long, generally not more than 5s, and the specific time should be determined comprehensively according to the heat source, welding power, cooling gas and other welding parameters.

[0058] Optionally, in order to improve the intelligence of welding, reduce the requirements of welding work on people and reduce labor costs, in some embodiments, the automatic start and stop of the second gas 13 is realized through a control system. Specifically, the method for intermittently opening the second gas 13 in step S402 is as follows:

[0059] S4021: When the second gas 13 is opened for the first time, the control system starts timing;

[0060] S4022: The control system opens the second gas 13 once every preset time T, and within the preset time T, the large droplet 802 generated on the welding wire 11 falls off from the welding wire 11 and the newly generated droplet 8 grows to a diameter exceeding a preset diameter.

[0061] The above scheme needs to open the second gas 13 for the first time, and the control system records the time of opening the second gas 13 this time and starts timing. In the subsequent, only need to open the second gas 13 once every fixed time T, the fixed time T is preset in advance, called preset time T, the length of the preset time T is designed, which can be determined according to the time from the last large droplet 802 generated on the welding wire 11 detaching from the welding wire 11 to the new droplet 8 generated on the welding wire 11 continuously growing to the diameter exceeding the preset diameter. The length of this process needs to be determined, which is related to heat source, welding power, cooling gas and other welding parameters, and needs to be determined comprehensively. Generally, it is within 10s.

[0062] Alternatively, in order to provide another method for improving the intelligence of welding, or to further improve the reliability and accuracy of the intermittent opening of the second gas 13 on the basis of the above scheme, in some embodiments, the state of the droplet 8 is further monitored by setting a shielding sensor 16 on the welding torch 1, and the control system realizes the automatic start and stop of the second gas 13 according to the state change of the droplet 8. Specifically, the welding torch 1 structure is as shown in Figure 10 and Figure 11 The shielding sensor 16 is arranged in a ring array design on the side of the cathode of the welding torch 1 to form a shielding monitoring area. Specifically, for laser-hollow tungsten arc coaxial composite welding, since the hollow tungsten electrode 101 needs to be powered to emit an arc, the temperature is very high. In order to prevent damage to the sensor, the shielding sensor 16 is arranged at the interval of the first gas nozzle 2 on the side of the hollow tungsten electrode 101. In this way, a circular shielding monitoring area can be formed like the first gas 9, and direct contact with the cathode can be avoided to damage the sensor. If further protection of the shielding sensor 16 is needed, a protective cover can be designed for the shielding sensor 16. Correspondingly, the shielding sensor 16 is arranged, and the method of intermittently opening the second gas 13 in step S402 of the above droplet control method includes:

[0063] S40211: When the diameter of the droplet 8 exceeds the edge of the shielding monitoring area, the shielding sensor 16 sends a signal to the control center 6, and the control center 6 controls the opening of the second gas 13, and the diameter of the shielding monitoring area is less than or equal to the diameter of the cylindrical gas curtain 12;

[0064] S40212: When the droplet 8 is separated and gradually away from the welding wire 11, and the distance between the droplet and the welding wire exceeds the monitoring range of the shielding sensor, the sensor restores and sends control information to the control center 6, and the control center 6 closes the second gas 13; the cathode end of the welding torch 1 is generally 83cm-10cm away from the droplet during welding, so the shielding sensor 16 is selected, and a near field communication sensor suitable for small distance detection is selected, such as an inductive proximity switch, a capacitive proximity switch, an ultrasonic sensor, a laser ranging sensor, a millimeter wave radar, etc. A shielding sensor 16 can be selected, and multiple shielding sensors 16 of the same type are arranged at intervals around the cathode, or multiple shielding sensors of different types can be arranged at intervals around the cathode. Various sensors complement each other to verify and further improve the accuracy of monitoring, so that the second gas 13 can be opened and closed more accurately, improving welding efficiency and quality.

[0065] It should be noted that the above-mentioned scheme of increasing the shielding sensor can be used with the above-mentioned control system timing control scheme, or it can be two different schemes used in parallel. The specific application can be freely selected according to the needs.

[0066] The terms "upper", "lower", "front", "back", "left", "right", etc. indicate the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0067] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part of the technical features, and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling molten droplets from welding wire, characterized in that, The method is applied in a weightless environment and includes... The first gas is turned on, forming an air curtain that is blown vertically toward the welding area of ​​the workpiece. When the welding device is turned on, the heat source at the cathode end of the welding torch acts on the end of the welding wire, which is located inside the medium air curtain. The tip of the welding wire generates molten droplets under the action of a heat source, and the molten droplets continue to grow; When the diameter of the molten droplet exceeds the preset diameter, the droplet is subjected to the force of the first gas and gradually detaches from the welding wire, moving towards the welding area; The molten droplets reach the welding area of ​​the workpiece and extend and fill the weld under the action of the first gas; Cooling completes the welding process; The end of the welding wire is located at the center of the air curtain, so that the molten droplets generated by the welding wire are located at the center of the air curtain, and the preset diameter is equal to the inner diameter of the cross-section of the air curtain; The method further includes: When the diameter of the molten droplet exceeds the preset diameter, the second gas is turned on. The second gas is blown from the center of the first gas in a direction perpendicular to the welding area toward the molten droplet. Under the action of the first gas and the second gas, the molten droplet detaches from the welding wire and moves toward the welding area. The second gas is turned on intermittently for less than 5 seconds. The method further includes: a ring array of shielding sensors is provided around the cathode of the welding torch to form a shielding monitoring area. When the diameter of the molten droplet exceeds the edge of the shielding monitoring area, the shielding sensor sends a signal to the control center, and the control center controls the second gas to be turned on. The diameter of the shielding monitoring area is less than or equal to the diameter of the medium air curtain. When the molten droplet detaches and gradually moves away from the welding wire, and the distance between the molten droplet and the welding wire exceeds the monitoring range of the obstruction sensor, the sensor recovers and sends control information to the control center, and the control center shuts off the second gas; the obstruction sensor is one or more of the following: inductive proximity switch, capacitive proximity switch, ultrasonic sensor, laser rangefinder, and millimeter-wave radar.

2. The control method according to claim 1, characterized in that, The second gas is intermittently turned on, including: The control system starts timing the first time the second gas is activated. The control system activates the second gas once every preset time T. During the preset time T, the molten droplets generated by the welding wire detach from the welding wire and the regenerated molten droplets grow to a diameter exceeding the preset diameter.

3. A welding wire droplet control system for implementing the method of claim 1 or 2, characterized in that, The control system includes a welding device, a first gas ejection device, a wire feeding device, and a control center. The welding device includes a welding torch and a power supply. The first gas ejection device includes a first jet nozzle, a first gas duct, a first gas driving device, and a first gas source. The first jet nozzle is connected to the first gas driving device through the first gas duct. The first gas driving device is connected to the control center and the first gas source. Under the control of the control center, the first gas is turned on and off. The first gas ejected from the first jet nozzle forms a medium air curtain, which is blown vertically toward the welding area of ​​the workpiece. The wire feeding device is used to continuously feed the wire and keep the end of the welding wire within the medium air curtain.

4. The control system according to claim 3, characterized in that, It also includes a second gas ejection device, which includes a second jet nozzle, a second air passage, a second gas driving device, and a second gas source. The second jet nozzle is located inside the ring formed by the first jet nozzle, and the second jet nozzle faces and is connected to the second gas driving device through the second air passage. The second gas driving device is connected to the control center and the second gas source, and the second gas is turned on and off under the control of the control center.

5. The control system according to claim 4, characterized in that, The welding device is a laser-hollow tungsten electrode coaxial composite welding device, with the first jet nozzle designed to surround the hollow tungsten electrode and the second jet nozzle located at the center of the hollow tungsten electrode.

6. The control system according to claim 5, characterized in that, There are multiple first air passages and / or first jet ports, arranged in a ring along the periphery of the hollow tungsten electrode, or The first air passage and / or the first jet outlet is an integral annular structure surrounding the hollow tungsten electrode.

7. The control system according to claim 6, characterized in that, An obstruction sensor is provided around the hollow tungsten electrode. The obstruction sensor is one or more of the following: an inductive proximity switch, a capacitive proximity switch, an ultrasonic sensor, a laser rangefinder, and a millimeter-wave radar.

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