Laser-hollow cathode arc hybrid coaxial torch and welding method

Abstract

The present application belongs to the technical field of laser-hollow cathode arc hybrid welding, and an embodiment provides a laser-hollow cathode arc coaxial welding torch and a welding method. In order to solve the problem that the penetration depth cannot continue to increase when the laser power is high, the space between the hollow cathode and the welding workpiece is cooled by compressed gas. In order to enhance the cooling effect, dry ice coolant is further arranged at the outlet of the cooling gas through a second channel, and the dry ice coolant is sprayed into the space between the hollow cathode and the welding workpiece by the pressure of the compressed gas. The space between the hollow cathode and the welding workpiece is further cooled or the metal vapor, air, inert gas, plasma and / or welding plume are discharged by the way of air blowing or air suction through the hollow cathode center, so as to avoid the influence of the gas above the arc and its high-temperature ionization on the laser transmission, and a greater penetration depth is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser-hollow cathode arc hybrid welding, and particularly relates to a laser-hollow cathode arc hybrid coaxial welding torch and a welding method. BACKGROUND

[0002] Welding, also known as fusion welding, is a manufacturing process and technology that uses heat, high temperature or high pressure to join metals or other thermoplastic materials such as plastics. Laser-hollow cathode arc hybrid welding technology combines the advantages of laser welding and arc welding, from the perspective of energy coupling, realizes the synergistic effect of the two heat sources, makes the heat source input more concentrated and efficient in the welding process, greatly improves the welding speed, and reduces the generation of welding defects such as pores and cracks. According to the positional relationship between the laser and the arc, the hybrid mode of laser-hollow cathode arc hybrid welding is divided into two modes: off-axis hybrid and coaxial hybrid. Compared with off-axis hybrid, coaxial hybrid can more effectively improve the synergistic effect of the two heat sources, improve the energy utilization rate, and obtain greater penetration and better welding quality. Therefore, it is more suitable for occasions with extremely high requirements for welding quality and energy utilization rate, such as aerospace and high-end equipment manufacturing.

[0003] In laser-hollow cathode arc hybrid welding, the greater the laser power, the greater the welding penetration and the better the welding quality. However, as the laser power increases, the welding penetration will not increase indefinitely. When the laser power reaches a certain level, the penetration will not continue to increase, especially when the laser power is high. This defect is a bottleneck for the development of laser-hollow cathode arc hybrid welding technology, and the reasons are as follows: During the laser-hollow cathode arc coaxial hybrid welding process, the laser passes through the center of the hollow cathode. On the one hand, the metal vapor, impurities, photo-induced plasma and other substances generated by the laser irradiation on the workpiece will continuously rise to the inside of the arc and the center of the hollow cathode, thereby affecting the transmission of the laser and reducing the heat reaching the workpiece, thus reducing the utilization rate of laser energy. At this time, even if the laser power is higher, the welding penetration will not continue to increase. On the other hand, as the welding process continues, the photo-induced plasma accumulates, especially when the laser power is high. The interaction between the photo-induced plasma and the arc speeds up, and the temperature of the arc becomes higher and higher. The high temperature of the arc causes the gas above the arc to be optically ionized and produce a burning wave, which absorbs laser energy and expands the plasma volume, thereby hindering the transmission of laser energy. Therefore, the coupling effect of the laser and the arc reaches a critical value, and further increasing the laser efficiency will actually reduce the welding penetration. This makes the laser-hollow cathode arc hybrid welding technology still have a lot of room for improvement when facing the demand for higher laser power for ultra-thick weldments. SUMMARY

[0004] The present application provides a laser-hollow cathode arc coaxial welding torch and a welding method to overcome the limitations of the prior art and obtain greater penetration.

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

[0006] Firstly, on the one hand, the present application provides a laser-hollow cathode arc coaxial welding torch, the peripheral side of the hollow cathode of the welding torch is provided with a first channel, the first channel has a heat insulation function, and the first channel is connected with a compressed gas storage device for delivering compressed gas to the first channel, so that the compressed gas is expanded and cooled in the first channel and then sprayed out from the cooling gas outlet at the lower part of the first channel.

[0007] Optionally, in some embodiments of the present application, 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 application, the above-mentioned welding torch further comprises a second channel for delivering dry ice coolant, part of the second channel is located below the cooling gas outlet, and the bottom and / or sidewall of this part of the second channel is provided with a plurality of small holes, and the second channel is connected with a dry ice output device.

[0009] Optionally, in some embodiments of the present application, the second channel extends upward to the outside of the first channel, and the corner of the second channel bending upward is a rounded corner.

[0010] Optionally, in some embodiments of the present application, the second channel is in communication with the first channel at the side close to the cooling gas outlet.

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

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

[0013] In a second aspect, the present application also provides a laser-hollow cathode arc combined coaxial welding method, which is realized based on the welding torch described above and comprises the following steps: turning on the laser-hollow cathode arc combined coaxial welding torch to make the welding torch generate an arc and the laser in the hollow cathode hit the welding area of the welding workpiece; monitoring the temperature change above the arc; and when the temperature above the arc reaches a preset threshold, turning on the compressed gas to make the compressed gas be delivered to the cooling gas outlet through the first channel and sprayed out to cool the space between the hollow cathode and the welding workpiece.

[0014] Optionally, in some embodiments of the present application, the welding method described above further comprises the following step: turning on the dry ice output device to make the dry ice enter below the cooling gas outlet through the second channel and be sprayed out 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 application, the welding method described above further comprises the following step: turning on the gas driving device above the third channel to make a negative pressure be formed inside the third channel to promote 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 deliver gas to the third channel to make a positive pressure be formed inside the third channel to cool the space between the hollow cathode and the welding workpiece and at the same time to promote the high-temperature area on the axis of the arc to move downward.

[0016] Compared with the prior art, the present application has the following advantages:

[0017] The present application cools the space between the hollow cathode and the welding workpiece by the compressed gas to prevent the temperature of the arc and the metal vapor, air, inert gas, plasma and / or welding plume inside the arc from being too high, so that the gas above the arc is ionized to affect the transmission of the laser. In order to further enhance the cooling effect, the present application also sets the dry ice coolant in the second channel at the cooling gas outlet and sprays the dry ice coolant to the space between the hollow cathode and the welding workpiece by the pressure of the compressed gas, and further cools the space between the hollow cathode and the welding workpiece or discharges the metal vapor, air, inert gas, plasma and / or welding plume by the way of blowing or sucking air through the hollow cathode center, so as to avoid the welding plume and the gas above the arc being ionized by high temperature to affect the transmission of the laser, and improve the upper limit of the laser power that can be used in the laser-hollow cathode combined coaxial welding, so that the welding torch and the method of the structure of the present application can obtain greater welding penetration under the same welding current. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and together with the description serve to explain the present application. In the drawings:

[0019] Figure 1 is a schematic diagram of the cross section of the torch structure of embodiment 1 of the present application;

[0020] Figure 2 is a schematic diagram of the process flow of the welding method of embodiment 1 of the present application

[0021] Figure 3 is a schematic diagram of the cross section of the torch structure of embodiment 2 of the present application;

[0022] Figure 4 is a schematic diagram of the process flow of the welding method of embodiment 2 of the present application;

[0023] Figure 5 is a schematic diagram of the cross section of the torch structure of embodiment 3 of the present application;

[0024] Figure 6 is a schematic diagram of the bottom view of the torch structure of embodiment 3 of the present application;

[0025] Figure 7 is a schematic diagram of the cross section of the torch structure of embodiment 4 and embodiment 5 of the present application;

[0026] Figure 8 is a schematic diagram of the process flow of the welding method of embodiment 4 of the present application;

[0027] Figure 9 is a schematic diagram of the process flow of the welding method of embodiment 5 of the present application.

[0028] wherein 1 is a hollow tungsten electrode, 2 is a first channel, 3 is a compressed gas storage device, 4 is a ring valve, 5 is a cooling gas outlet, 6 is a workpiece to be welded, 7 is a molten pool, 8 is an electric arc, 9 is a laser, 10 is a dry ice output device, 11 is a second channel, 111 is a vertical section of the second channel, 112 is a horizontal section of the second channel, 12 is dry ice coolant, 13 is a third channel, and 14 is a gas driving device. DETAILED DESCRIPTION

[0029] In order to make the present application more clearly, specifically and intelligibly understood, the present application is described below through specific embodiments.

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

[0031] For the orientation words, if there are terms "center", "transverse", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like in the description and claims of the present application, the orientation and position relationship based on the orientation or position relationship shown in the drawings is indicated, which is only for the convenience of describing the present application and simplifying the description, and cannot be understood as indicating or implying that the device or element 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", "third" and the like in the description and claims of the present application are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence.

[0033] The terms "include" and "have" and any variations thereof in the description and claims of the present application are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] When an element is referred to as "fixed to" or "provided on" another element, it can be directly on the other element or a middle element can be present at the same time. When an element is referred to as "connected to" another element, it can be directly connected to the other element or a middle element can be present at the same time. When an element is referred to as "provided with" another element, it can be provided on the surface or inside of the element.

[0035] Unless otherwise explicitly indicated, throughout the specification and claims, the term "comprise" or its variants such as "contain" or "include" and the like will be understood to include the stated element or component, without excluding other elements or components.

[0036] The term "electrically connected" in the description and claims of the present application can be a physical contact circuit connection, or a communication connection, which can be a wired communication connection or a wireless communication connection.

[0037] Embodiment 1

[0038] First, in one aspect, the embodiment provides a laser-hollow cathode arc combined coaxial welding torch, wherein the hollow cathode can select a suitable material of the cathode according to the design welding requirement, and the embodiment takes a hollow tungsten electrode as an example. The welding torch structure of the embodiment is as follows Figure 1As shown, the peripheral side of the hollow tungsten electrode 1 of the welding torch is provided with a first channel 2, the height of the first channel 2 can completely wrap the hollow cathode, or can partially wrap, which can be designed according to the actual use requirements, but the first channel 2 should not be too long or too short, too long, the gas travels too long through the first channel 2 to the cooling gas outlet 5, which reduces the speed of the ejected gas, and the long travel also increases heat exchange, which will also affect the cooling effect. Compressed gas can also be directly introduced into the first channel 2, and the compressed gas is directly ejected in the form of compressed gas from the cooling gas outlet 5, and the compressed gas starts to expand and do work on the outside at the moment of ejection from the cooling gas outlet 5, which is cooled and becomes cooling gas. The upper end or side of the first channel 2 is provided with an inlet, which is connected to the compressed gas storage device 3, and the inlet can be one or more, and the embodiment sets the inlet at the upper end of the first channel 2, which is beneficial to the expansion and cooling of compressed air. The first channel 2 is designed to be heat-insulated and has heat-insulating function, and optionally, an insulating layer can be provided on the inner wall or outer wall of the first channel 2, or the first channel 2 can be made of heat-insulating material. In the embodiment, the inner wall is provided with the insulating layer, and the cooling gas outlet 5 is provided at one end of the first channel 2 close to the hollow cathode discharge end, that is, the lower end of the first channel 2 is the cooling gas outlet 5, which is located near the discharge end of the hollow tungsten electrode 1. Optionally, the above-mentioned compressed gas can be air or inert gas, such as argon, helium, nitrogen, carbon dioxide, which can be a single component gas or a mixture of one or more of the above-mentioned gases. In the embodiment, welding is performed on the surface of 8mm thick high-strength steel, and high-purity argon gas with a purity of 99.999% is selected as the compressed gas. The compressed gas storage device 3 can be a stainless steel gas tank, a carbon steel gas tank, etc. The laser of the embodiment selects n-LIGHT-1056393 fiber laser, the maximum power is 1000W, the output mode is divided into continuous and pulse two kinds, the frequency and duty cycle are adjustable, the modulation frequency is ≤100kHz, the rise and fall time is ≤5μs. The laser wavelength is 1070±10nm, the focal spot diameter is 0.2mm, the laser head focusing focal length is 150mm, and the beam quality is ≤4.0mm-mrad. The arc welding power source adopts Panasonic YC-300WXH model welder, the welding test adopts direct current positive connection mode, the arc mode selects direct current, and the cooling mode is air cooling.

[0039] During the welding process, the compressed gas enters the first channel 2 from the compressed gas storage tank. Since the first channel 2 is designed to be adiabatic, the compressed gas expands adiabatically in the first channel 2. According to the principle of adiabatic expansion of compressed gas, the gas expands without exchanging heat with the outside world, does work to the outside to consume the internal energy of the compressed gas; during the adiabatic expansion of the gas, the average distance between the molecules increases, and the potential energy between the molecules increases, but since there is no energy from the outside to the molecules, the increase of the molecular potential energy can only be realized by the decrease of the molecular kinetic energy. And the decrease of the molecular kinetic energy, the temperature of the gas decreases. Therefore, in this embodiment, the compressed gas realizes the expansion and refrigeration process in the process of passing through the first channel 2, and obtains argon gas with certain cold energy. The compressed gas storage device 3 will continuously deliver compressed gas to the first channel 2, and do work on the argon gas in the first channel 2 which has been expanded and cooled, generating a huge thrust on the argon gas, so that the ice-cold argon gas is sprayed out from the cooling gas outlet 5 of the first channel 2. The ice-cold argon gas is sprayed downward and to the left and right sides at the same time. The argon gas sprayed downward can effectively cool the arc 8, and the argon gas sprayed to the left and right sides can expand the cooling range of the argon gas. The argon gas sprayed to one side of the hollow tungsten electrode 1 further cools the area directly below the center of the hollow tungsten electrode 1, reduces the temperature of the space in the middle of the arc 8, and the argon gas sprayed away from the side of the hollow tungsten electrode 1 further cools the space around the arc 8, accelerates the heat exchange between the arc 8 and the surrounding environment, and promotes the faster cooling of the arc 8. In this way, through the joint action of the three directions, the space between the hollow cathode and the welding workpiece 6 is cooled efficiently, thereby preventing the temperature above the arc 8 and inside the arc 8 from being too high to cause the ionization of the gas therein, affecting the transmission of the laser 9, and realizing the laser-hollow cathode arc complex coaxial welding with higher power to obtain greater penetration.

[0040] It should be noted that since the hollow tungsten electrode 1 generates arc 8 after being electrified, its temperature is very high. The adiabatic design of the first channel 2 has the advantage of preventing the heat of the hollow tungsten electrode 1 from being transferred to the argon gas in the first channel 2, affecting the refrigeration effect of the argon gas, and also preventing the tungsten electrode heat from spreading, improving energy utilization.

[0041] Optionally, the cooling gas outlet 5 of the welding torch is also provided with an annular valve 4 for opening, closing and / or adjusting the gas flow. Since the first channel 2 is designed to be heat-insulated, it is generally sealed. When cooling is needed, the compressed gas storage tank is opened, and the compressed gas enters the first channel 2, expands and fills the first channel 2. Then, the annular valve 4 is opened. The control mode of the annular valve 4 includes one or more of remote control, manual control and automatic control. The automatic control can be realized by using a valve made of temperature-sensitive 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 is automatically opened. Or, when the gas pressure in the first channel 2 reaches a certain level, the annular valve 4 is automatically opened under the action of the pressure.

[0042] In another aspect, the embodiment also provides a laser-hollow cathode arc complex coaxial welding method based on the above welding torch. The flow is as shown in Figure 2 The method comprises the following steps:

[0043] S1: Turn on the laser-hollow cathode arc complex coaxial welding torch, so that the welding torch generates an arc 8, and the laser 9 in the hollow cathode hits the welding area of the welding workpiece 6;

[0044] S2: Monitor the temperature change above the arc 8. When the temperature above the arc 8 reaches a preset threshold, open the compressed gas, so that the compressed gas is delivered to the cooling gas outlet 5 through the first channel 2 and sprayed out, to cool the space between the hollow cathode and the welding workpiece 6. The monitoring of the temperature change above the arc 8 can be manual monitoring, for example, measuring the temperature above the arc 8 at intervals with a temperature measuring instrument, or an additional temperature sensor can be arranged on the welding torch or beside the welding area to display the temperature above the arc 8 in real time. Opening the compressed gas includes opening the compressed gas storage device 3 and opening the annular valve 4, so that the compressed gas can cool the space between the hollow cathode and the welding workpiece 6.

[0045] Embodiment 2

[0046] Embodiment 2 is further optimized on the basis of embodiment 1, and the specific implementation is as follows.

[0047] On the basis of embodiment 1, the laser-hollow cathode arc complex coaxial welding torch of the embodiment further comprises a second channel 11 for delivering 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 arranged on the bottom and / or side wall of the part of the second channel 11. The second channel 11 is connected with a dry ice output device 10, as shown in Figure 3 .

[0048] 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.

[0049] In order to reduce the resistance of the cooling gas, more retain the pressure of the cooling gas on the dry ice and the pressure after being sprayed, and reduce the influence on the cooling effect, the second channel 11 of the embodiment is communicated with the first channel 2 at the side close to the cooling gas outlet 5. That is, the side close to the cooling gas outlet 5 of the second channel 11 is not provided with a side wall, or the side wall at the side close to the cooling gas outlet 5 is provided with a notch matched with the cooling gas outlet 5, so as to reduce a layer of obstacles, so that the cooling gas is directly sprayed into the second channel 11 after being sprayed from the first channel 2, carries the dry ice coolant 12 to spray out of the second channel 11, and more retains the cooling effect.

[0050] The embodiment also provides a laser-hollow cathode arc coaxial welding method based on the laser-hollow cathode arc coaxial welding torch. Figure 4 As shown in the figure, the method comprises the following steps.

[0051] S1: Turn on the laser-hollow cathode arc coaxial welding torch, so that the welding torch generates an arc 8, and the laser 9 in the hollow cathode hits the welding area of the welding workpiece 6;

[0052] S2: Monitor the temperature change above the arc 8; when the temperature above the arc 8 reaches a preset threshold, turn on the compressed gas, so that the compressed gas is conveyed to the cooling gas outlet 5 through the first channel 2 and sprayed out, and the space between the hollow cathode and the welding workpiece 6 is cooled. The monitoring of the temperature change above the arc 8 can be manual monitoring, for example, measuring the temperature above the arc 8 at intervals by using a temperature measuring instrument, or an additional temperature sensor can be arranged on the welding torch or beside the welding area to display the temperature above the arc 8 in real time; turning on the compressed gas includes turning on the compressed gas storage device 3 and turning on the annular valve 4, so as to realize the cooling of the space between the hollow cathode and the welding workpiece 6 by the compressed gas;

[0053] S3: After turning on the compressed gas in the above S2, the dry ice output device 10 is also turned on, so that the dry ice enters below the cooling gas outlet 5 through the second channel 11, and is sprayed out together with the compressed gas under the pressure of the compressed gas, so as to cool the space between the hollow cathode and the welding workpiece 6.

[0054] Embodiment 3

[0055] The second channel 11 in the embodiment 2 is a ring-shaped channel coaxial with the hollow tungsten electrode 1. In actual application, it is found that the dry ice coolant 12 moves from the outside of the ring-shaped channel to the center by translation, and the driving force for its forward movement is completely provided by the dry ice output device 10, and the dry ice output device 10 can only input dry ice at one or more places of the second channel 11 to provide a pushing force. The planar ring structure is not conducive to uniformly pushing the dry ice to each part of the ring and to the hollow tungsten electrode 1 at the center of the ring. Therefore, on the basis of the embodiment 2, the shape and structure of the second channel 11 of the welding torch are optimized in the embodiment, Figure 5 The specific structure of the welding torch of the embodiment is shown, and the bottom view is as shown in Figure 6 In the embodiment, the second channel 11 extends upward to the outside of the first channel 2, and the 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, the dry ice 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 will slide downward into the horizontal section under the action of gravity, and further continuously translate to the lower side of the cooling gas outlet 5 under the pushing force of the gravity of the subsequent dry ice, and be blown out of the second channel 11 by the cooling gas to cool the space between the hollow tungsten electrode 1 and the workpiece. The corner of the second channel 11 is rounded, which is more conducive to the smooth sliding of the dry ice in the vertical section 111 of the second channel to the horizontal section 112 of the second channel, reduces the residence of the dry ice at the corner, and ensures the stable supply of the dry ice.

[0056] Embodiment 4

[0057] In order to further improve the effect of the present application, the applicant further optimizes the above-mentioned embodiment 1, embodiment 2 and embodiment 3, that is, a gas driving device 14 is connected to the upper end of the third channel 13 in the hollow cathode, the gas driving device 14 can be adjusted to a positive pressure mode or a negative pressure mode, and is used for inputting gas into the third channel 13 to form a positive pressure or extracting gas in the third channel 13 to form a negative pressure. The specific structure is shown in Figure 7 The present scheme can be combined with any one of the embodiment 1, embodiment 2 or embodiment 3, and can be flexibly combined according to needs and conditions in actual application, and the technical effects are also different.

[0058] In the embodiment 4, the gas driving device 14 is adjusted to the positive pressure mode, and the gas is introduced into the third channel 13 to form a positive pressure, and the gas can be a compressed gas or a common inert gas, and the 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, so that the high temperature area below the tungsten electrode is lowered, the path of the high temperature influence on the transmission path is shortened, the influence on the transmission of the laser 9 is reduced, and the influence of the temperature on the transmission of the laser 9 is further relieved to a certain extent. It is found in specific implementation that the closer the high temperature area is to the workpiece, the more obvious the relief effect is, and even when the high temperature area enters the molten pool 7, the gas in the space above the workpiece is less likely to be ionized, and the influence on the transmission of the laser 9 is weaker.

[0059] The embodiment also provides a laser-hollow cathode arc coaxial welding method based on the laser-hollow cathode arc coaxial welding torch. Figure 8 As shown in the figure, the method comprises the following steps.

[0060] S1: Turn on the laser-hollow cathode arc coaxial welding torch, so that the welding torch generates an arc 8, and the laser 9 in the hollow cathode hits the welding area of the welding workpiece 6;

[0061] S2: Monitor the temperature change above the arc 8; when the temperature above the arc 8 reaches a preset threshold, turn on the compressed gas, so that the compressed gas is delivered to the cooling gas outlet 5 through the first channel 2 and sprayed out, and the space between the hollow cathode and the welding workpiece 6 is cooled. The temperature change above the arc 8 can be monitored manually, for example, the temperature above the arc 8 is measured by a temperature measuring instrument at intervals, or a temperature sensor is additionally arranged on the welding torch or beside the welding area to display the temperature above the arc 8 in real time; turning on the compressed gas includes turning on the compressed gas storage device 3 and turning on the annular valve 4, so that the compressed gas can cool the space between the hollow cathode and the welding workpiece 6;

[0062] S3: After the compressed gas is turned on in the above S2, the dry ice output device 10 is also turned on, so that the dry ice enters below the cooling gas outlet 5 through the second channel 11 and is sprayed out together with the compressed gas under the pressure of the compressed gas, and the space between the hollow cathode and the welding workpiece 6 is cooled;

[0063] The welding method further comprises S4: turning on the gas driving device 14 above the third channel 13, introducing the gas into the third channel 13, so that a positive pressure is formed in the third channel 13, the space between the hollow cathode and the welding workpiece 6 is cooled, and the high temperature area on the axis of the arc 8 is lowered.

[0064] Since the scheme of the embodiment can be combined with any of the embodiments 1, 2 or 3, there are many combinations and schemes, and therefore the corresponding welding method is not limited to the above, for example, S3 can be present or absent in the above scheme, and the order of S2 and S3 and S4 is not limited to the above order, and other orders are also possible.

[0065] Embodiment 5

[0066] Embodiment 5 is based on the scheme in embodiment 4, the gas driving device 14 is adjusted to negative pressure mode, the gas inside the third channel 13 is extracted by the gas driving device 14 to form negative pressure, so that the metal vapor, air, inert gas, plasma and / or welding plume above the arc 8 and inside the arc 8 and in the third channel 13 are discharged through the third channel 13, so that the high-temperature metal vapor, air, inert gas, plasma and / or welding plume above the arc 8 can be continuously discharged, and the new gas escaping from the workpiece has not yet had time to rise to a very high temperature, thereby fundamentally avoiding the problem of ionization of the gas above the arc 8 under high temperature affecting the transmission of the laser 9, so that a higher power laser 9 can be used to improve the welding penetration.

[0067] Correspondingly, the process of the laser-hollow cathode arc coaxial welding method of the embodiment is as shown in Figure 9 Compared with embodiment 4, the step S4 of the welding method of the embodiment is changed to:

[0068] Turning on the gas driving device 14 above the third channel 13 to form negative pressure inside the third channel 13, so as to promote the metal vapor, air, inert gas, plasma and / or welding plume above and inside the arc 8 to be discharged through the third channel 13.

[0069] In summary, the embodiment of the present application optimizes the design of the welding torch structure, sets the heat-insulating first channel 2 on the side of the hollow tungsten electrode 1, and uses compressed gas supplemented by dry ice coolant 12 to cool the space between the hollow cathode and the welding workpiece 6, preventing the temperature of the arc 8 and the metal vapor, air, inert gas, plasma and / or welding plume inside the arc 8 from being too high, and further preventing the phenomenon of ionization of the gas above the arc 8 by the way of blowing gas or negative pressure extraction of high-temperature gas in the center, thereby realizing the use of higher energy and higher power laser 9 to obtain greater penetration, making the laser-hollow tungsten electrode coaxial composite welding technology cross the technical bottleneck and further develop.

[0070] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent features, and these modifications or replacements 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 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, and the first channel has a heat-insulating function. The first channel is connected to a compressed gas storage device for conveying compressed gas to the first channel, so that after the compressed gas expands and cools down in the first channel, the compressed gas storage device is also used to continuously convey the compressed gas to the first channel, do work on the gas that has expanded and cooled down in the first channel, generate a huge thrust on the gas, and make the cold gas ejected from the cooling gas outlet of the first channel. When the cold gas is ejected, it will be ejected downward and to the left and right sides at the same time. The gas ejected downward can effectively cool the arc, and the gas ejected to both sides The cooling range of the gas is expanded. The gas sprayed to one side of the hollow cathode further cools the area directly below the center of the hollow cathode, reducing the temperature of the middle space of the arc. The gas sprayed to the side away from the hollow cathode will further cool the space around the arc, accelerate the heat exchange between the arc and the surrounding environment, and promote the arc to cool down faster. In this way, through the joint action of three directions, the space between the hollow cathode and the welding workpiece is efficiently cooled, thereby preventing the temperature above and inside the arc from being too high, causing the gas therein to ionize and affect the laser transmission, thereby achieving laser-hollow cathode arc composite coaxial welding at higher power and obtaining greater penetration depth.

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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