Laser-hollow cathode arc complex coaxial welding torch and welding method

Abstract

The invention belongs to the technical field of laser-hollow cathode arc composite welding. The embodiment of the invention provides a laser-hollow cathode arc composite coaxial welding torch and a welding method. In order to solve the problem that the fusion depth cannot be continuously increased when the laser power is relatively high, the space between the hollow cathode and the welding workpiece is cooled through compressed gas, and in order to enhance the cooling effect, a dry ice coolant is further arranged at a cooling gas outlet through a second channel, so that the cooling effect is improved. A dry ice cooling agent is sprayed to the space between the hollow cathode and the welding workpiece by means of the pressure of compressed gas, and the space between the hollow cathode and the welding workpiece is further cooled or metal steam, air, inert gas, plasma and / or welding plumes are discharged in a manner of blowing or sucking air from the center of the hollow cathode; therefore, the influence of gas above the electric arc and high-temperature ionization of the gas on laser transmission is avoided, and a larger fusion depth is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of laser-hollow cathode arc composite welding, and in particular to a laser-hollow cathode arc composite coaxial welding torch and a welding method. Background Art

[0002] Welding, also known as fusion or melting, is a manufacturing process and technology that uses heating, high temperature or high pressure to join metals or other thermoplastic materials such as plastics. Laser-hollow cathode arc hybrid welding technology, due to its organic combination of the advantages of laser welding and arc welding, realizes the synergistic effect of the two heat sources from the perspective of energy coupling, making the heat source input more concentrated and efficient during the welding process, greatly improving the welding speed, and reducing the occurrence of welding defects such as pores and cracks. According to the different positional relationships between the two heat sources of laser and arc, the composite methods of laser-hollow cathode arc hybrid welding are divided into two types: off-axis composite and coaxial composite. Compared with off-axis composite, coaxial composite can improve the synergistic effect of the two heat sources to a greater extent, improve energy utilization, obtain greater penetration and better welding quality, and is therefore more suitable for occasions with extremely high requirements for welding quality and energy utilization, such as aerospace, high-end equipment manufacturing and other fields.

[0003] In laser-hollow cathode arc hybrid welding, the higher the laser power, the greater the weld penetration and the significantly improved weld quality. However, as the laser power increases, the weld penetration does not increase indefinitely. That is, after the laser power reaches a certain level, the weld penetration cannot continue to increase. Especially at high laser powers, this defect has become a bottleneck in the development of laser-hollow cathode arc hybrid welding technology. The reasons are as follows: During laser-hollow cathode arc coaxial hybrid welding, the laser passes through the center of the hollow cathode. On the one hand, the metal vapor, impurities, and photoinduced plasma generated by the laser irradiation on the workpiece continuously rise into the arc and the center of the hollow cathode, thereby affecting the transmission of the laser and reducing the heat reaching the workpiece, thereby reducing the utilization rate of the laser energy. At this point, even at higher laser power, the weld penetration cannot continue to increase. On the other hand, as the welding progresses, the photoinduced plasma accumulates continuously. Especially at high laser power, the interaction between the photoinduced plasma and the arc accelerates, the arc temperature increases, and the high arc temperature triggers optical breakdown ionization of the gas above the arc, generating a combustion wave, which absorbs the laser energy and causes the plasma volume to expand, hindering the transmission of laser energy. Therefore, at this time, the dual heat source coupling effect of laser and arc reaches a critical value. If the laser efficiency is further improved, the welding penetration will decrease. This means that there is still a lot of room for technical improvement in laser-hollow cathode arc hybrid welding technology when facing demands such as ultra-thick welds that require higher laser power. Summary of the Invention

[0004] In order to solve the problem in the prior art that the penetration depth cannot be further increased when the laser power is high, the present invention provides a laser-hollow cathode arc composite coaxial welding torch and a welding method, thereby overcoming the limitations of the prior art and achieving a greater penetration depth.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions.

[0006] First, on the one hand, the present invention provides a laser-hollow cathode arc composite coaxial welding torch, wherein a first channel is provided on the peripheral side of the hollow cathode of the welding torch, the first channel having a heat-insulating function, and the first channel is connected to a compressed gas storage device for delivering compressed gas to the first channel, so that the compressed gas expands and cools down in the first channel and is ejected from the cooling gas outlet at the lower part of the first channel.

[0007] Optionally, in some embodiments of the present invention, the cooling gas outlet is provided with an annular valve for opening, closing and / or adjusting the gas flow, and the control mode of the annular valve includes one or more of remote control, manual control, and automatic control.

[0008] Optionally, in some embodiments of the present invention, the welding torch further includes a second channel for conveying dry ice coolant, a portion of the second channel is located below the cooling gas outlet, and a plurality of small holes are provided on the bottom and / or side wall of this portion of the second channel, and the second channel is connected to a dry ice output device.

[0009] Optionally, in some embodiments of the present invention, the second channel extends upward to the outside of the first channel, and the upwardly curved corners of the second channel are rounded.

[0010] Optionally, in some embodiments of the present invention, the second channel is connected to the first channel on a side close to the cooling gas outlet.

[0011] Optionally, in some embodiments of the present invention, the compressed gas is an inert gas, including one or more of argon, helium, nitrogen, and carbon dioxide.

[0012] Optionally, in some embodiments of the present invention, the upper end of the third channel inside the hollow cathode is connected to a gas driving device for introducing gas into the third channel to form a positive pressure or extracting gas from the third channel to form a negative pressure.

[0013] In a second aspect, the present invention also provides a laser-hollow cathode arc composite coaxial welding method, which is implemented based on the above-mentioned welding torch, including: turning on the laser-hollow cathode arc composite coaxial welding torch so that the welding torch generates an arc, and the laser in the hollow cathode hits the welding area of the welding workpiece; monitoring the temperature changes above the arc; when the temperature above the arc reaches a preset threshold, turning on the compressed gas so that the compressed gas is transported to the cooling gas outlet through the first channel and ejected, thereby cooling the space between the hollow cathode and the welding workpiece.

[0014] Optionally, in some embodiments of the present invention, the above-mentioned welding method further includes: turning on the dry ice output device, so that the dry ice enters below the cooling gas outlet through the second channel, and is ejected together with the compressed gas under the pressure of the compressed gas to cool the space between the hollow cathode and the welding workpiece.

[0015] Optionally, in some embodiments of the present invention, the above-mentioned welding method further includes: turning on the gas driving device above the third channel to form a negative pressure inside the third channel, prompting the metal vapor, air, inert gas, plasma and / or welding plume above and inside the arc to be discharged through the third channel; or turning on the gas driving device above the third channel to introduce gas into the third channel to form a positive pressure inside the third channel, cooling the space between the hollow cathode and the welding workpiece, and at the same time prompting the high-temperature zone on the arc axis to move downward.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses compressed gas to cool the space between the hollow cathode and the welding workpiece, preventing the arc and the metal vapor, air, inert gas, plasma, and / or welding plume within the arc from overheating, which could cause ionization of the gas above the arc and thus affect laser transmission. To further enhance the cooling effect, the present invention also provides dry ice coolant at the cooling gas outlet through a second channel, and sprays the dry ice coolant into the space between the hollow cathode and the welding workpiece using the pressure of the compressed gas. Furthermore, the space between the hollow cathode and the welding workpiece is further cooled or metal vapor, air, inert gas, plasma, and / or welding plume is expelled by blowing or suctioning air from the center of the hollow cathode, thereby preventing the welding plume and the gas above the arc from being ionized by high temperature and affecting laser transmission. This increases the upper limit of the laser power that can be used in laser-hollow cathode composite coaxial welding, and thus, at the same welding current, the welding torch and method of the present invention can achieve greater welding penetration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 1 is a schematic cross-sectional view of the welding torch structure of Example 1 of the present invention; Figure 2 This is a schematic diagram of the welding method flow in Example 1 of the present invention. Figure 3 2 is a schematic cross-sectional view of a welding torch structure according to embodiment 2 of the present invention; Figure 4 This is a schematic flow chart of the welding method according to embodiment 2 of the present invention; Figure 5 2 is a schematic cross-sectional view of a welding torch structure according to embodiment 3 of the present invention; Figure 6 3 is a bottom view schematic diagram of the welding torch embodiment of the present invention; Figure 7 Schematic cross-sectional view of the welding torch structure of Embodiment 4 and Embodiment 5 of the present invention; Figure 8 This is a schematic flow chart of the welding method according to embodiment 4 of the present invention; Figure 9 It is a schematic flow chart of the welding method according to embodiment 5 of the present invention.

[0018] Among them, 1-hollow tungsten electrode, 2-first channel, 3-compressed gas storage device, 4-annular valve, 5-cooling gas outlet, 6-welding workpiece, 7-molten pool, 8-arc, 9-laser, 10-dry ice output device, 11-second channel, 111-vertical section of the second channel, 112-horizontal section of the second channel, 12-dry ice coolant, 13-third channel, 14-gas drive device. DETAILED DESCRIPTION

[0019] In order to make the present application more clearly, detailed and understandable, the present application is described below through specific embodiments.

[0020] In the description of this invention, the following terms need to be explained: As for directional words, if the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like in the specification and claims of this application indicate directions and positional relationships, they are based on the directions or positional relationships shown in the accompanying drawings and 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, and should not be understood as limiting the specific scope of protection of the present invention.

[0021] The terms "first," "second," "third," etc. in the description and claims of this application are used to distinguish similar objects and are not necessarily used to describe a particular sequence or order.

[0022] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0023] When an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intervening element. When an element is referred to as being "provided with" another element, it may be provided on the surface of or within the element.

[0024] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0025] The term "electrical connection" in the specification and claims of this application may refer to a circuit connection with physical contact or a communication connection, which may be a wired communication connection or a wireless communication connection.

[0026] Example 1

[0027] First, on the one hand, this embodiment provides a laser-hollow cathode arc composite coaxial welding torch, wherein the hollow cathode can be selected according to the design welding requirements, and the hollow tungsten electrode is used as an example in this embodiment. Figure 1As shown, a first channel 2 is provided around the hollow tungsten electrode 1 of the welding torch. The height of the first channel 2 can completely or partially enclose the hollow cathode, and can be designed according to the specific actual deactivation requirements. However, the design of the first channel 2 should not be too long or too short. If it is too long, the gas will have a long journey through the first channel 2 to reach the cooling gas outlet 5, resulting in a reduced gas velocity. A longer journey also increases heat exchange, which will also affect the cooling effect. Alternatively, compressed gas can be directly introduced into the first channel 2 and ejected directly from the cooling gas outlet 5 in the form of compressed gas. The compressed gas begins to expand the moment it is ejected from the cooling gas outlet 5, performing external work and cooling it to become cooling gas. An inlet is provided at the upper end or side of the first channel 2 and is connected to the compressed gas storage device 3. The inlet may be one or more. In this embodiment, the inlet is provided at the upper end of the first channel 2 to facilitate the expansion and cooling of the compressed air. The first channel 2 is thermally insulated and has a thermal insulation function. Optionally, an insulating layer may be provided on the inner or outer wall of the first channel 2, or the first channel 2 may be made of an insulating material. In this embodiment, the inner wall is selected as the insulating layer. A cooling gas outlet 5 is provided at the end of the first channel 2 near the hollow cathode discharge end. That is, the cooling gas outlet 5 is provided at the lower end of the first channel 2 and is located near the discharge point of the hollow tungsten electrode 1. Optionally, the compressed gas may be air or an inert gas such as argon, helium, nitrogen, or carbon dioxide. It may be a single-component gas or a mixture of one or more of the above gases. This example uses 8mm thick high-strength steel for welding. High-purity argon with a purity of 99.999% is used as the compressed gas. Compressed gas storage device 3 can be a stainless steel or carbon steel tank. The laser used in this example is an n-LIGHT-1056393 fiber laser with a maximum power of 1000W. The output modes include continuous and pulsed, with adjustable frequency and duty cycle. The modulation frequency is ≤100kHz, and the rise and fall times are ≤5μs. The laser wavelength is 1070±10nm, the focal spot diameter is 0.2mm, the laser head has a focal length of 150mm, and the beam quality is ≤4.0mm-mrad. A Panasonic YC-300WXH arc welding machine was used as the arc welding power source. The welding test used a DC positive connection method, with DC arc mode selected and air cooling as the cooling method.

[0028] During the welding process, compressed gas enters the first channel 2 from the compressed gas storage tank. Because the first channel 2 is insulated, the compressed gas undergoes adiabatic expansion within the first channel 2. According to the principle of adiabatic expansion of compressed gas, the gas expands without exchanging heat with the outside world, performing work externally to consume the compressed gas's internal energy. During this adiabatic expansion process, the average distance between the gas molecules increases, increasing their potential energy. However, since no external energy is supplied to the molecules, this increase in molecular potential energy can only be achieved by reducing their kinetic energy. As molecular kinetic energy decreases, the gas temperature decreases. Therefore, in this embodiment, the compressed gas undergoes both expansion and cooling as it passes through the first channel 2, producing argon gas with a certain cooling capacity. The compressed gas storage device 3 continuously delivers compressed gas to the first channel 2, performing work on the already expanded and cooled argon gas within the first channel 2, generating a significant thrust on the argon gas, causing the cold argon gas to be ejected from the cooling gas outlet 5 of the first channel 2. When the cold argon gas is ejected, it will be ejected downward and to the left and right sides at the same time. The argon gas ejected downward can effectively cool the arc 8, and the argon gas ejected to both sides will expand the cooling range of the argon gas. The argon gas sprayed to one side of the hollow tungsten electrode 1 will further cool the area directly below the center of the hollow tungsten electrode 1, and reduce the temperature of the middle space of the arc 8. The argon gas sprayed to the side away from the hollow tungsten electrode 1 will further cool the space around the arc 8, accelerate the heat exchange between the arc 8 and the surrounding environment, and promote faster cooling of the arc 8. In this way, through the joint action of three directions, the space between the hollow cathode and the welding workpiece 6 is efficiently cooled, thereby preventing the temperature above and inside the arc 8 from being too high, causing the gas therein to ionize, affecting the transmission of the laser 9, thereby achieving laser-hollow cathode arc composite coaxial welding at higher power and obtaining a greater penetration depth.

[0029] It should be noted that, since the hollow tungsten electrode 1 discharges to generate an arc 8 after being energized, its temperature is very high. The thermal insulation design of the first channel 2 has another advantage, which is to prevent the heat of the hollow tungsten electrode 1 from being transferred to the argon gas in the first channel 2, affecting the cooling effect of the argon gas. At the same time, it can also prevent the heat of the tungsten electrode from diffusing, thereby improving energy utilization.

[0030] Optionally, the cooling gas outlet 5 of the welding torch is further provided with an annular valve 4 for opening, closing and / or adjusting the gas flow. Since the first channel 2 is an adiabatic design, the first channel 2 is generally a sealed design. When cooling is required, the compressed gas storage tank is opened, and the compressed gas enters the first channel 2, completes expansion and fills the first channel 2, then the annular valve 4 needs to be opened. The control method of the annular valve 4 includes one or more of remote control, manual control, and automatic control. The automatic control can be achieved by using a valve made of temperature-sensitive material or pressure-sensitive material. When the temperature in the space between the hollow tungsten electrode 1 and the welding workpiece 6 reaches a certain level, the annular valve 4 automatically opens, or when the gas pressure in the first channel 2 reaches a certain level, the annular valve 4 automatically opens under the action of pressure.

[0031] On the other hand, this embodiment also provides a laser-hollow cathode arc composite coaxial welding method based on the above welding torch, the process is as follows: Figure 2 As shown, the following steps are included: S1: Turn on the laser-hollow cathode arc composite coaxial welding torch so that the torch generates an arc 8 and the laser 9 in the hollow cathode hits the welding area of the welding workpiece 6; S2: Monitor temperature changes above the arc 8; when the temperature above the arc 8 reaches a preset threshold, activate the compressed gas, allowing the compressed gas to be transported through the first channel 2 to the cooling gas outlet 5 and ejected, thereby cooling the space between the hollow cathode and the welding workpiece 6. Monitoring temperature changes above the arc 8 can be done manually, for example, by periodically measuring the temperature above the arc 8 with a thermometer. Alternatively, an additional temperature sensor can be provided on the welding torch or near the welding area to display the temperature above the arc 8 in real time. Activating the compressed gas includes activating the compressed gas storage device 3 and the annular valve 4, which allows the compressed gas to cool the space between the hollow cathode and the welding workpiece 6.

[0032] Example 2

[0033] Example 2 is based on Example 1, and the technical solution is further optimized as follows.

[0034] On the basis of Example 1, the laser-hollow cathode arc composite coaxial welding torch of this embodiment further includes a second channel 11 for conveying dry ice coolant 12. Part of the second channel 11 is located below the cooling gas outlet 5, that is, part of the second channel 11 must be located below the cooling gas outlet 5, and a plurality of small holes are provided on the bottom and / or side wall of this part of the second channel 11. The second channel 11 is connected to the dry ice output device 10, specifically as shown in FIG. Figure 3 shown.

[0035] Optionally, the second channel 11 can be an annular channel coaxially arranged with the hollow tungsten electrode 1 and located directly below the hollow tungsten electrode 1. The bottom and / or side walls of the portion of the second channel 11 directly below the hollow tungsten electrode 1 are designed to be a hollow structure. The bottom and / or side walls of the portion not directly below the hollow tungsten electrode 1 can be a closed structure, or can be hollow or have other structures with small holes. In order to facilitate the ejection of the dry ice coolant 12, the torch of this embodiment is designed to have this portion as a hollow structure, specifically as follows: Figure 3 As shown. In specific implementations, a layer of high-temperature-sensitive material, such as a polymer film with a relatively low decomposition temperature, can be laid on the inner wall of the second channel 11. During the welding process, the temperature of the arc 8 and plasma below gradually increases, heating the second channel 11. When the temperature reaches a certain level, reaching the decomposition temperature of the polymer film, the film decomposes under the high temperature, leaking small holes. This effectively opens the small holes in the previously closed hollow structure, facilitating the subsequent discharge of dry ice coolant 12. The second channel 11 is provided with a dry ice inlet, which is connected to a dry ice dispensing device 10. There can be multiple dry ice inlets, or a single one. Because dry ice is a solid powder with poor fluidity, it is particularly difficult to distribute evenly within a ring-shaped channel in a short period of time. Therefore, this embodiment uses multiple dry ice inlets, namely, multiple dry ice inlets spaced along the circumference of the second channel 11. In this embodiment, there are three dry ice inlets. These dry ice inlets can be connected to the same dry ice dispensing device 10 or to separate dry ice dispensing devices 10. The dry ice output device 10 has the function of continuously pushing dry ice coolant 12 into the second channel 11. When the dry ice coolant 12 enters the second channel 11 from the dry ice output device 10 and moves to the portion of the second channel 11 directly below the hollow tungsten electrode 1 under the action of thrust, cooling gas is ejected from the cooling gas outlet 5 of the first channel 2 and enters the second channel 11 directly below the hollow tungsten electrode 1. Under the pressure of the cooling gas, the dry ice coolant 12 in the second channel 11 is ejected from the second channel 11 through the small holes in the bottom and / or side walls of the second channel 11 and is sprayed to the left, right, and downward directions according to the direction of the cooling gas ejection. When the dry ice coolant 12 encounters high temperatures, it instantly sublimates, removing a large amount of heat, thereby cooling the metal vapor, air, inert gas, plasma, and / or welding plume in the space between the hollow cathode and the welding workpiece 6.

[0036] To reduce the resistance of the cooling gas, maximize the pressure of the cooling gas on the dry ice and the pressure after ejection, and reduce the impact on the cooling effect, the second channel 11 of this embodiment intersects with the first channel 2 on the side near the cooling gas outlet 5. In other words, the side of the second channel 11 near the cooling gas outlet 5 has no sidewall, or the sidewall near the cooling gas outlet 5 has a notch that matches the cooling gas outlet 5. This reduces one layer of obstruction, allowing the cooling gas to directly enter the second channel 11 after being ejected from the first channel 2, carrying the dry ice coolant 12 out of the second channel 11, and thus maximize the cooling effect.

[0037] This embodiment also provides a laser-hollow cathode arc hybrid coaxial welding method based on the above laser-hollow cathode arc hybrid coaxial welding torch, such as Figure 4 As shown, including: S1: Turn on the laser-hollow cathode arc composite coaxial welding torch so that the torch generates an arc 8 and the laser 9 in the hollow cathode hits the welding area of the welding workpiece 6; S2: Monitor temperature changes above the arc 8. When the temperature above the arc 8 reaches a preset threshold, activate the compressed gas flow, allowing it to be transported through the first channel 2 to the cooling gas outlet 5 and ejected, thereby cooling the space between the hollow cathode and the welding workpiece 6. Monitoring temperature changes above the arc 8 can be done manually, for example, by periodically measuring the temperature above the arc 8 with a thermometer. Alternatively, an additional temperature sensor can be installed on the welding torch or near the welding area to display the temperature above the arc 8 in real time. Activating the compressed gas flow includes activating the compressed gas storage device 3 and the annular valve 4, which allows the compressed gas to cool the space between the hollow cathode and the welding workpiece 6. S3: After the compressed gas is turned on in S2 above, the dry ice output device 10 is also turned on, so that the dry ice enters the lower part of the cooling gas outlet 5 through the second channel 11. Under the pressure of the compressed gas, the dry ice is ejected together with the compressed gas to cool the space between the hollow cathode and the welding workpiece 6.

[0038] Example 3

[0039] The second channel 11 in Example 2 is an annular channel coaxial with the hollow tungsten electrode 1. In actual application, it was found that the dry ice coolant 12 moved from the outside of the annular channel to the center by translation. The driving force for its advancement was completely provided by the dry ice output device 10. In addition, the dry ice output device 10 could only input dry ice at one or more locations in the second channel 11 to provide thrust. The flat annular structure was not conducive to evenly pushing the dry ice to various parts of the annular ring and to the hollow tungsten electrode 1 at the center of the annular ring. Therefore, based on Example 2, this embodiment optimized the shape and structure of the second channel 11 of the welding torch. Figure 5The specific structure of the welding torch of this embodiment is shown in FIG. Figure 6 As shown. In this embodiment, the second channel 11 extends upward to the outside of the first channel 2, and the upwardly curved corner of the second channel 11 is rounded. In this way, after the dry ice output device 10 inputs the dry ice into the second channel 11, it will accumulate in the vertical section 111 of the second channel, and as the dry ice at the horizontal section 112 of the second channel is gradually consumed and reduced, the dry ice in the vertical section 111 of the second channel slides down into the horizontal section under the action of gravity, and under the subsequent thrust of the gravity of the dry ice, it further continuously moves horizontally to the bottom of the cooling gas outlet 5, and is blown out of the second channel 11 by the cooling gas, cooling the space between the hollow tungsten electrode 1 and the workpiece. The corner of the second channel 11 is set as a rounded corner, which is more conducive to the dry ice in the vertical section 111 of the second channel sliding smoothly to the horizontal section 112 of the second channel, reducing the dry ice from staying at the corner and ensuring a stable supply of dry ice.

[0040] Example 4

[0041] In order to further improve the effect of the present invention, the applicant has made further optimization on the basis of the above-mentioned embodiment 1, embodiment 2, and embodiment 3, that is, the upper end of the third channel 13 inside the hollow cathode of the welding torch is connected to a gas drive device 14, and the gas drive device 14 can be adjusted to a positive pressure mode or a negative pressure mode, for introducing gas into the third channel 13 to form a positive pressure or extracting gas from the third channel 13 to form a negative pressure. For the specific structure, please refer to Figure 7 This solution can be combined with any one of Example 1, Example 2 or Example 3. In actual applications, the combination can be flexibly performed according to needs and circumstances, and the technical effects are also different.

[0042] In Example 4, the gas drive device 14 is adjusted to a positive pressure mode, and gas is introduced into the third channel 13 to form a positive pressure. The gas can be compressed gas or ordinary inert gas. Compressed gas has a better cooling effect and can cool the third channel 13 to a certain extent. In addition, the gas is introduced into the center of the hollow tungsten electrode 1, which can move the high-temperature zone below the tungsten electrode downward. This shortens the path affected by the high temperature on the transmission path, reduces the impact on the transmission of the laser 9, and can further alleviate the impact of temperature on the transmission of the laser 9 to a certain extent. During specific implementation, it was found that the closer the high-temperature zone is to the workpiece, the more obvious this mitigation effect is. Even when the high-temperature zone enters the molten pool 7, the gas in the space above the workpiece is less likely to be ionized, and the impact on the transmission of the laser 9 is weaker.

[0043] This embodiment also provides a laser-hollow cathode arc hybrid coaxial welding method based on the above laser-hollow cathode arc hybrid coaxial welding torch, such as Figure 8 Shown, including: S1: Turn on the laser-hollow cathode arc composite coaxial welding torch so that the torch generates an arc 8 and the laser 9 in the hollow cathode hits the welding area of the welding workpiece 6; S2: Monitor temperature changes above the arc 8. When the temperature above the arc 8 reaches a preset threshold, activate the compressed gas flow, allowing it to be transported through the first channel 2 to the cooling gas outlet 5 and ejected, thereby cooling the space between the hollow cathode and the welding workpiece 6. Monitoring temperature changes above the arc 8 can be done manually, for example, by periodically measuring the temperature above the arc 8 with a thermometer. Alternatively, an additional temperature sensor can be installed on the welding torch or near the welding area to display the temperature above the arc 8 in real time. Activating the compressed gas flow includes activating the compressed gas storage device 3 and the annular valve 4, which allows the compressed gas to cool the space between the hollow cathode and the welding workpiece 6. S3: After the compressed gas is turned on in S2, the dry ice output device 10 is also turned on, so that the dry ice enters the lower portion of the cooling gas outlet 5 through the second channel 11. Under the pressure of the compressed gas, the dry ice is ejected together with the compressed gas to cool the space between the hollow cathode and the welding workpiece 6. The above welding method also includes S4: turning on the gas driving device 14 above the third channel 13 to introduce gas into the third channel 13, so that a positive pressure is formed inside the third channel 13, thereby cooling the space between the hollow cathode and the welding workpiece 6 and causing the high-temperature zone on the axis of the arc 8 to move downward.

[0044] Since the solution of this embodiment can be combined with any of Example 1, Example 2 or Example 3, there are many combination forms and solutions. Therefore, the corresponding welding method is not limited to the above. For example, S3 may or may not be present in the above solution, and the order of S2, S3 and S4 is not limited to the above order, and other orders are also possible.

[0045] Example 5

[0046] Example 5 is based on the solution in Example 4. The gas drive device 14 is adjusted to a negative pressure mode. The gas inside the third channel 13 is extracted by the gas drive device 14 to form a negative pressure, thereby discharging the metal vapor, air, inert gas, plasma and / or welding plume above the arc 8, inside the arc 8 and in the third channel 13 through the third channel 13. In this way, the high-temperature metal vapor, air, inert gas, plasma and / or welding plume above the arc 8 can be continuously discharged. At the same time, the temperature of the new gas escaping from the workpiece has not yet risen to a very high level, thereby fundamentally avoiding the problem of the gas above the arc 8 being ionized at high temperature and affecting the transmission of the laser 9, thereby making it possible to use a higher power laser 9 and improve the welding penetration.

[0047] Accordingly, the laser-hollow cathode arc composite coaxial welding method of this embodiment is as follows: Figure 9 As shown, compared with Example 4, step S4 of the welding method of this embodiment is changed to: The gas driving device 14 above the third channel 13 is turned on to form a negative pressure inside the third channel 13, so that the metal vapor, air, inert gas, plasma and / or welding plume above and inside the arc 8 are discharged through the third channel 13.

[0048] In summary, the embodiments of the present invention optimize the design of the welding torch structure, set an insulated first channel 2 on the side of the hollow tungsten electrode 1, and use compressed gas supplemented by dry ice coolant 12 to cool the space between the hollow cathode and the welding workpiece 6 to prevent the arc 8 and the metal vapor, air, inert gas, plasma and / or welding plume inside the arc 8 from being too high in temperature. At the same time, by blowing gas into the center or extracting high-temperature gas by negative pressure in the center, the gas above the arc 8 is further prevented from being ionized, thereby achieving a greater penetration depth using a higher energy and higher power laser 9, so that the laser-hollow tungsten electrode coaxial composite welding technology can overcome the technical bottleneck and be further developed.

[0049] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will appreciate that modifications may be made to the technical solutions described in the aforementioned embodiments, or that some of the technical features may be replaced with equivalents. Such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A laser-hollow cathode arc composite coaxial welding torch, characterized in that: A first channel is provided on the peripheral side of the hollow cathode of the welding torch. The first channel has an insulating function. The first channel is connected to a compressed gas storage device for transporting compressed gas to the first channel, so that the compressed gas expands and cools down in the first channel and is ejected from the cooling gas outlet at the lower part of the first channel.

2. The welding torch according to claim 1, characterized in that The cooling gas outlet is provided with an annular valve for opening, closing and / or adjusting the gas flow rate. The control mode of the annular valve includes one or more of remote control, manual control and automatic control.

3. The welding torch according to claim 1, characterized in that It also includes a second channel for conveying dry ice coolant. Part of the second channel is located below the cooling gas outlet, and the bottom and / or side wall of this part of the second channel are provided with multiple small holes. The second channel is connected to the dry ice output device.

4. The welding torch according to claim 3, characterized in that The second channel extends upward to the outside of the first channel, and the upwardly bent corner of the second channel is a rounded corner.

5. The welding torch according to claim 3, characterized in that The second channel is connected to the first channel at a side close to the cooling gas outlet.

6. The welding torch according to claim 1, characterized in that The compressed gas is an inert gas, including one or more of argon, helium, nitrogen, and carbon dioxide.

7. The welding torch according to claim 1, characterized in that The upper end of the third channel inside the hollow cathode is connected to a gas driving device for introducing gas into the third channel to form a positive pressure or extracting gas from the third channel to form a negative pressure.

8. A laser-hollow cathode arc hybrid coaxial welding method, implemented based on the welding torch according to any one of claims 1 to 7, characterized in that: include: Turn on the laser-hollow cathode arc composite coaxial welding torch so that the torch generates an arc and the laser in the hollow cathode hits the welding area of the welding workpiece; Monitor temperature changes above the arc; When the temperature above the arc reaches a preset threshold, the compressed gas is turned on so that the compressed gas is transported to the cooling gas outlet through the first channel and ejected to cool the space between the hollow cathode and the welding workpiece.

9. The welding method according to claim 8, characterized in that: Also includes: The dry ice output device is turned on, so that the dry ice enters below the cooling gas outlet through the second channel and is ejected together with the compressed gas under the pressure of the compressed gas to cool the space between the hollow cathode and the welding workpiece.

10. The welding method according to claim 8, characterized in that: Also includes: Turning on the gas drive device above the third channel to create a negative pressure inside the third channel, thereby causing the metal vapor, air, inert gas, plasma and / or welding plume above and inside the arc to be discharged through the third channel; or The gas drive device above the third channel is turned on to introduce gas into the third channel, so that positive pressure is formed inside the third channel, which cools the space between the hollow cathode and the welding workpiece and causes the high-temperature area on the arc axis to move downward.

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