Vacuum laser welding penetration stabilization device and method

Abstract

The present invention relates to the technical field of vacuum laser welding. The present invention provides a vacuum laser welding penetration stabilization device and method, which are used in a vacuum laser welding system, wherein the vacuum laser welding system includes a vacuum welding chamber, a laser welding gun, and an exhaust assembly; the penetration stabilization device includes: a secondary current detection system and an exhaust control system, wherein the secondary current detection system is used to collect the potential difference between the base material to be welded and the welding smoke at a certain position above it, and obtain the secondary current according to the potential difference, and the exhaust control system is used to control the exhaust rate of the exhaust assembly according to the secondary current. The present invention can accurately grasp the vacuum environment state within a certain range above the molten pool through the setting of the penetration stabilization device, thereby timely adjusting the exhaust rate, ensuring that the molten pool area is in a better operating state, ensuring the stability of the weld penetration, and improving the quality of the welded joint, which has important significance and application prospects in the field of ships and deep-sea equipment.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum laser welding, and in particular to a vacuum laser welding penetration stabilization device and method. Background Art

[0002] For titanium alloy thick plate welding, electron beam welding can achieve good joint quality, but electron beam welding needs to be carried out in a vacuum chamber, and large titanium alloy structural parts cannot be laser welded due to size limitations. Narrow gap welding methods are widely used in titanium alloy thick plate welding, but due to the large plate thickness, narrow gap welding requires multi-layer and multi-pass welding, and the welding efficiency is low. At the same time, the deformation control of thick plate welding is difficult, which cannot meet the requirements of efficient welding of large structures.

[0003] In the 1980s, researchers proposed that laser welding under vacuum conditions could improve the utilization rate of laser energy, improve the penetration ability of the incident laser, and significantly increase the weld penetration depth. However, due to the limitation of laser power, the depth-to-width ratio of the weld is much lower than that of electron beam welding. Therefore, electron beam welding is more commonly used for titanium alloy thick plates. In recent years, with the emergence of high-power and high-quality lasers, researchers have found that high-power lasers can also obtain large depth-to-width ratio welds similar to electron beam welding under vacuum, and vacuum laser welding does not require the extremely high vacuum required for electron beam welding. At the same time, laser welding does not have the problem of scattering of electrons by atmospheric molecules, and does not require radiation protection.

[0004] Chinese patent CN201920016636.3 discloses a vacuum laser welding machine, including a closed cavity with a peripheral wall and a top wall, a first observation window arranged on the peripheral wall, and a laser through lens arranged on the top wall. The closed cavity is connected to a vacuum device and a dust suction device respectively, and the first observation window can be opened or closed on the peripheral wall. A laser welding head is suspended above the laser through lens. The vacuum laser welding machine controls laser welding in a closed vacuum environment, and the plasma plume generated by laser induction is significantly reduced, so that the refraction and reflection losses of the laser are reduced, the required laser power becomes smaller, and the energy acting on the welding point is stable, which can effectively reduce the amount of metal vaporization, so that less dust is generated. At the same time, the amount of gas in the vacuum environment is very small, and the metal solution rises along the wall of the molten pool, and the bubbles can quickly run out. Therefore, there are very few pores in the vacuum environment, and its melting depth is deeper and more stable than that under atmospheric pressure. This patent reduces the refraction and reflection of the assembly by welding in a vacuum environment. However, researchers have found that when performing vacuum laser welding, even if the vacuum level in the vacuum chamber is maintained to meet the requirements, the weld penetration depth often fluctuates. This situation is prone to partial incomplete penetration, seriously affecting the mechanical properties of the weld joint and the production yield. This is especially true in technical fields such as aerospace and shipbuilding, which require more precise welding quality. There are major safety hazards in the weld joints. Summary of the invention

[0005] The technical problem solved by the present invention is that, in the prior art, when the vacuum degree meets the requirements, the penetration depth formed in the vacuum laser welding process will fluctuate, and in some cases the penetration depth will not meet the requirements, seriously affecting the quality of the welded joint.

[0006] The invention discloses a vacuum laser welding penetration stabilizing device, which is used in a vacuum laser welding system. The vacuum laser welding system comprises:

[0007] A vacuum welding chamber is used to form a vacuum welding environment on the surface of the base material to be welded;

[0008] A laser welding gun, used to generate a laser beam to weld the base material to be welded;

[0009] A vacuum assembly, used for sucking gas in the vacuum welding chamber to form a vacuum welding environment;

[0010] The penetration stabilization device includes: a secondary current detection system and an exhaust control system. The secondary current detection system is used to collect the potential difference between the base material to be welded and the welding smoke at a certain position above it, and obtain the secondary current according to the potential difference. The exhaust control system is used to control the exhaust rate of the exhaust component according to the secondary current.

[0011] According to the plasma fluctuation characteristics, the electron movement speed is relatively fast during the laser welding process, which can form a potential difference relative to the direction of the laser incident axis. Through the above-mentioned setting, the potential difference can be collected to accurately analyze the environmental state near the molten pool in the vacuum welding chamber. Therefore, the vacuum rate of the vacuum assembly is adjusted according to the detection result of the secondary current, which can more accurately control the vacuum environment above the molten pool in the vacuum welding chamber, thereby ensuring the smooth progress of the welding process and enabling the vacuum laser welding process to obtain a melting depth that meets the requirements.

[0012] Furthermore, the secondary current detection system includes a load circuit and an oscilloscope device, the load circuit is used to detect the potential difference between the base material to be welded and the welding smoke at a certain position above it, the oscilloscope device is used to detect the potential difference, calculate the corresponding secondary current based on the potential difference, and transmit the secondary current to the exhaust control system, and at the same time display the secondary current in the form of a waveform, and the exhaust control system controls the exhaust rate of the exhaust component according to the size of the received secondary current.

[0013] Through the above-mentioned arrangement, the battery difference between a certain position above the molten pool in the vacuum welding chamber and the base material to be welded can be detected during vacuum laser welding, and the corresponding secondary current can be calculated based on the potential difference. The concentration of welding smoke above the molten pool can be judged by the size of the secondary current, thereby indirectly reflecting the vacuum state within a certain range above the molten pool, providing reliable reference data for the stable progress of vacuum laser welding and obtaining a stable penetration depth, thereby helping to change the local vacuum state during vacuum laser welding and obtain a stable and reliable welding penetration depth.

[0014] Furthermore, the load circuit includes a secondary current collector and a load resistor, the secondary current collector is connected to a first end of the load resistor, the second end of the load resistor is connected to a base material to be welded to form a loop, the oscilloscope device is connected in parallel to the load resistor, the secondary current collector is arranged in the vacuum welding chamber, and its collection end is located at a certain position above the molten pool during the welding process, and the other end of the secondary current collector is connected to the load resistor.

[0015] The secondary current collector is used to conduct the potential difference between it and the surface of the base material to be welded out of the vacuum welding chamber. The potential difference forms a voltage drop on the load resistor, thereby realizing real-time collection of the potential difference and facilitating the calculation and acquisition of the secondary current.

[0016] Furthermore, the collecting end of the secondary current collecting electrode is located 5 to 15 cm above the molten pool.

[0017] The above arrangement can accurately detect the vacuum environment state within the range above the molten pool, thereby facilitating more accurate control of the environment state of the welding area.

[0018] Furthermore, the secondary current collector is a thin copper plate.

[0019] The thin copper plate has good conductivity and can collect the corresponding potential difference more accurately and transmit it out of the vacuum welding chamber.

[0020] Furthermore, the vacuum control system includes a comparison and analysis module and a vacuum speed control module. The comparison and analysis module is communicatively connected to the oscilloscope device, and is used to obtain the value of the secondary current and compare the value of the secondary current with a preset threshold. The vacuum speed control module is used to adjust the vacuum rate of the vacuum component according to the comparison result.

[0021] The preset threshold needs to be obtained through preliminary vacuum laser welding tests. According to the support vector machine, the correlation analysis is performed on the secondary current and the weld penetration parameter to obtain the characterization relationship between the secondary current and the penetration. According to the above characterization relationship, the secondary current corresponding to the required penetration of the thickness of the base material to be welded can be selected as the preset threshold. During the welding process, when it is detected that the secondary current is greater than or equal to the preset threshold, the exhaust rate of the exhaust component is increased. When it is detected that the secondary current is less than the preset threshold, the exhaust rate of the exhaust component is maintained.

[0022] Furthermore, the penetration stabilization device can be used for stable control of weld penetration of one or two of titanium alloys, steels, and aluminum alloys during vacuum laser welding.

[0023] The present invention also discloses a vacuum laser welding method with stable penetration depth, using the above-mentioned penetration stabilization device, the welding method comprises:

[0024] Step S1: Preparation before welding: Process the groove of the base material to be welded as required, and process its surface to meet the welding requirements, and then assemble it on the welding support component;

[0025] Step S2: evacuating the vacuum welding chamber to make its vacuum degree meet the welding requirements;

[0026] Step S3: After the vacuum degree meets the requirement, the laser welding gun is started to perform welding;

[0027] Step S4: synchronously detecting the secondary current at a certain position above the molten pool during the welding process, and controlling the exhaust rate of the exhaust component according to the relationship between the secondary current and a preset threshold value;

[0028] Step S5: After welding is completed, the laser welding gun is turned off, and after a first preset time, the exhaust assembly is turned off.

[0029] The advantages of the welding method and the above-mentioned penetration stabilization device over the prior art are the same and will not be described in detail here.

[0030] Further, in step S4, controlling the air extraction rate of the air extraction component according to the relationship between the secondary current and the preset threshold value includes:

[0031] The detected secondary current is compared with a preset threshold value. When it is detected that the secondary current is greater than or equal to the preset threshold value, the pumping rate of the pumping component is increased. When it is detected that the secondary current is less than the preset threshold value, the pumping rate of the pumping component is maintained.

[0032] When it is detected that the secondary current is greater than or equal to the preset threshold, it means that under the influence of the plasma cloud and smoke above the molten pool, the vacuum degree near the molten pool is difficult to meet the requirements. In this case, the welding penetration depth is likely to become shallower and it is difficult to meet the requirements. At this time, increasing the exhaust rate of the exhaust assembly can increase the speed of extracting the plasma cloud and smoke, thereby reducing its impact on the laser beam, ensuring the welding penetration depth, and thus obtaining the required welding quality.

[0033] Further, in step S5, the first preset time is 30-60s.

[0034] After welding is completed, closing the exhaust assembly after the first preset time can properly maintain the vacuum environment in the vacuum welding chamber during the cooling process of the weld to prevent the weld from being oxidized by premature contact with air and affecting the quality of the weld joint.

[0035] Compared with the prior art, the vacuum laser welding penetration stabilization device and method described in the present invention have the following advantages:

[0036] The present invention, through the provision of a penetration stabilizing device, can accurately grasp the vacuum environment state within a certain range above the molten pool, thereby timely adjusting the exhaust rate to ensure that the molten pool area is in an optimal operating state, thereby ensuring the stability of the weld penetration and improving the quality of the weld joint. It has important significance and application prospects in the field of ships and deep-sea equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic structural diagram of the vacuum laser welding system and the penetration stabilization device described in an embodiment of the present invention.

[0038] Description of reference numerals:

[0039] 100. Vacuum welding chamber; 200. Laser welding gun; 300. Support component; 400. Base material to be welded; 500. Load circuit; 510. Secondary current collector; 520. Load resistor; 600. Oscilloscope device; 700. Air extraction control system; 800. Air extraction assembly; 810. Air extraction pipeline; 820. Air extraction pump. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0041] A vacuum laser welding penetration stabilization device and method according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Example 1

[0042] This embodiment provides a vacuum laser welding penetration stabilization device. Figure 1 As shown, it is used for a vacuum laser welding system, and the vacuum laser welding system includes:

[0043] The vacuum welding chamber 100 is used to form a vacuum welding environment on the surface of the base material 400 to be welded;

[0044] A laser welding gun 200, used to generate a laser beam to weld a base material 400 to be welded;

[0045] The vacuum assembly 800 is used to vacuum the gas in the vacuum welding chamber 100 to form a vacuum welding environment;

[0046] The penetration stabilization device includes: a secondary current detection system and an exhaust control system 700. The secondary current detection system is used to collect the potential difference between the base material 400 to be welded and the welding smoke at a certain position above it, and obtain the secondary current according to the potential difference. The exhaust control system 700 is used to control the exhaust rate of the exhaust assembly 800 according to the secondary current.

[0047] The researchers of this application found that the vacuum detection in the existing vacuum laser welding process is to measure the entire vacuum chamber using a vacuum gauge or a vacuum gauge, which detects the average vacuum degree of the entire vacuum chamber. During the vacuum laser welding process, a large amount of welding smoke (including metal vapor and smoke) will be generated at the part where the base material contacts the laser. The metal vapor absorbs the laser beam and is ionized into a plasma cloud, so that the vacuum degree of the part above the molten pool in the vacuum chamber is much worse than the vacuum degree of other positions. That is to say, when the vacuum detection device detects that the vacuum degree is qualified, it reflects that the overall average vacuum degree in the vacuum chamber is qualified, but the plasma cloud above the molten pool will cause the vacuum degree of the local area near the molten pool to be unqualified, and will consume the energy of the laser beam to a certain extent, causing the penetration depth during laser welding to fluctuate. In severe cases, local incomplete penetration will occur, resulting in unqualified joint quality. This problem has been plaguing the field of vacuum laser welding in recent years, but the current vacuum detection equipment cannot accurately measure the vacuum degree near the weld molten pool, and the stability of the molten pool in the welding process is more directly affected by the vacuum degree above and around it. At present, there is no method and device that can directly detect the vacuum degree near the molten pool, resulting in the inability to solve the above technical problems. According to the characteristics of plasma fluctuations, the electron movement speed is relatively fast during the laser welding process, which can form a potential difference relative to the direction of the laser incident axis. In this embodiment, through the above-mentioned setting, after collecting the potential difference, the environmental state near the molten pool position in the vacuum welding chamber 100 can be accurately analyzed. Therefore, the vacuum rate of the vacuum assembly 800 is adjusted according to the detection result of the secondary current, which can more accurately control the vacuum environment above the molten pool in the vacuum welding chamber 100, thereby ensuring the smooth progress of the welding process and enabling the vacuum laser welding process to obtain a melting depth that meets the requirements. It should be noted that the vacuum welding chamber 100 is provided with other components such as lenses for the laser to pass through, which can refer to the prior art and are not limited here. Among them, a certain position refers to a position 5 to 15 cm above the base material 400 to be welded and / or the molten pool, preferably 10 cm.

[0048] As one of the embodiments of the present invention, the secondary current detection system includes a load circuit 500 and an oscilloscope device 600. The load circuit 500 is used to detect the potential difference between the base material 400 to be welded and the welding smoke at a certain position above it. The oscilloscope device 600 is used to detect the potential difference, calculate the corresponding secondary current according to the potential difference, and transmit the secondary current to the exhaust control system 700, and display the secondary current in the form of a waveform. The exhaust control system 700 controls the exhaust rate of the exhaust component 800 according to the magnitude of the received secondary current. It should be noted that any one of the secondary current waveform displayed by the oscilloscope device 600 and the transmitted secondary current can be a value amplified N times according to a preset logic, or it can be an actual calculated value. The N is a preset magnification factor, which is not limited here. The secondary current can be obtained according to I=U / R, where I is the secondary current, U is the voltage (potential difference) across the load resistor, and R is the resistance value of the load resistor. The corresponding secondary current value can be obtained through the above calculation. It should be noted that due to the extremely small potential difference, the detected secondary current value is also extremely small, which can be amplified by an oscilloscope device and displayed and / or transmitted to the exhaust control system 700. Through the above setting, the battery difference between a certain position above the molten pool in the vacuum welding chamber 100 and the parent material 400 to be welded can be detected during vacuum laser welding, and the corresponding secondary current can be calculated based on the potential difference. The concentration of welding smoke above the molten pool can be judged by the size of the secondary current, thereby indirectly reflecting the vacuum state within a certain range above the molten pool, providing reliable reference data for the stable progress of vacuum laser welding and obtaining a stable penetration depth, thereby helping to change the local vacuum state during vacuum laser welding and obtain a stable and reliable welding penetration depth. The oscilloscope device 600 is an oscilloscope or other equipment that can detect voltage or current signals and display them as waveforms, which is not limited here.

[0049] In this embodiment, the load circuit 500 includes a secondary current collector 510 and a load resistor 520, wherein the secondary current collector 510 is connected to a first end of the load resistor 520, and a second end of the load resistor 520 is connected to the base material 400 to be welded to form a loop, and the oscilloscope device 600 is connected in parallel with the load resistor 520, and the secondary current collector 510 is arranged in the vacuum welding chamber 100, and its collection end is located at a certain position above the molten pool during the welding process, and the other end of the secondary current collector 510 is connected to the load resistor 520. The secondary current collector 510 is used to derive the potential difference between it and the surface of the base material 400 to be welded from the vacuum welding chamber 100, and the potential difference forms a voltage drop on the load resistor 520, thereby realizing the real-time collection of the potential difference, which is convenient for calculating and obtaining the secondary current. It should be noted that the end of the secondary current collector 510 is arranged close to the axis of the laser beam, so as not to interfere with the normal welding of the laser beam.

[0050] As one of the preferred embodiments, the secondary current collector 510 is a thin copper plate. The thin copper plate has good conductivity, can collect the corresponding potential difference more accurately, and transmit it out of the vacuum welding chamber 100. It should be understood that the wiring of the thin copper plate and the wiring of the base material 400 to be welded are sealed and insulated with the shell of the vacuum welding chamber 100 to prevent gas from entering the interior of the vacuum welding chamber 100 through the assembly position and affecting the vacuum degree of the welding area.

[0051] As one of the optional embodiments, the collection end of the secondary current collector 510 is located 5 to 15 cm above the molten pool. Preferably, the collection end of the secondary current collector 510 is located 10 cm above the molten pool. The above setting can accurately detect the vacuum environment state within the range above the molten pool, thereby helping to more accurately control the environment state of the welding area. The collection end is Figure 1 The middle secondary current collector 510 is close to one end of the welding laser beam.

[0052] In this embodiment, the exhaust control system 700 includes a comparison analysis module and an exhaust speed control module. The comparison analysis module is connected to the oscilloscope device 600 for obtaining the value of the secondary current and comparing the value of the secondary current with a preset threshold. The exhaust speed control module is used to adjust the exhaust rate of the exhaust component 800 according to the comparison result. The preset threshold needs to be obtained through the previous vacuum laser welding test. According to the support vector machine, the secondary current and the penetration parameter of the weld are subjected to correlation analysis to obtain the characterization relationship between the secondary current and the penetration. According to the above characterization relationship, the secondary current corresponding to the required penetration of the thickness of the base material 400 to be welded can be selected as the preset threshold. During the welding process, when it is detected that the secondary current is greater than or equal to the preset threshold, the exhaust rate of the exhaust component 800 is increased. When it is detected that the secondary current is less than the preset threshold, the exhaust rate of the exhaust component 800 is maintained. It should be noted that the characterization relationship can be a correlation relationship diagram or a correlation comparison table. It should be noted that the position of the collecting end of the secondary current collector 510 above the molten pool during the previous vacuum laser welding test is consistent with the position during actual welding, thereby ensuring the reliability of the preset threshold value of the secondary current.

[0053] Specifically, in the vacuum laser welding test, the semiconductor laser backlight source, narrowband filtering, and image processing technology are combined to filter and amplify the collected electrical signal through the op amp, compare the messy signal through the comparator, and perform signal shaping processing through the shaper. The main frequency of the signal and the energy ratio of the main frequency area are selected as characteristic parameters to characterize the signal, remove the welding interference signal, and extract the specific current signal output value according to the characteristic parameters, thereby obtaining the value of the secondary current. Among them, the narrowband filtering, image processing technology, etc. are all existing technologies and are not limited here.

[0054] In this embodiment, the exhaust assembly 800 includes an exhaust pipeline 810 and an exhaust pump 820. One end of the exhaust pipe 430 is connected to the inner cavity of the vacuum welding chamber 100, and the other end is connected to the exhaust pump 820. Before and during welding, the exhaust pump 820 extracts the gas in the inner cavity of the vacuum welding chamber 100 in real time through the exhaust pipeline 810 to ensure the stability of its vacuum degree, so that vacuum laser welding can be carried out smoothly.

[0055] It should be noted that the vacuum welding chamber 100 can be a chamber that completely accommodates the base material 400 to be welded, or it can be a local vacuum laser welding chamber that forms a local vacuum space on the surface of the base material 400 to be welded. The penetration stabilization device can accurately detect the secondary current of the welding smoke within a certain range above the molten pool during the welding process, thereby ensuring the stability of the penetration during the welding process and obtaining good welding joint quality.

[0056] It should be noted that the penetration stabilization device provided in this embodiment can be used for stable control of weld penetration during vacuum laser welding of metal structures such as titanium alloy, steel, and aluminum alloy. Example 2

[0057] This embodiment provides a vacuum laser welding method with stable penetration depth, using the penetration stabilization device as described in Embodiment 1, and the welding method includes:

[0058] Step S1: Preparation before welding: Process the groove of the base material 400 to be welded as required, and process its surface to meet the welding requirements, and then assemble it onto the welding support component 300;

[0059] Step S2: evacuating the vacuum welding chamber 100 to make its vacuum degree meet welding requirements;

[0060] Step S3: After the vacuum degree meets the requirement, the laser welding gun 200 is started to perform welding;

[0061] Step S4: synchronously detecting the secondary current at a certain position above the molten pool during the welding process, and controlling the exhaust rate of the exhaust assembly 800 according to the relationship between the secondary current and a preset threshold value;

[0062] Step S5: After welding is completed, the laser welding gun 200 is turned off, and after a first preset time, the exhaust assembly 800 is turned off.

[0063] Through the above settings, the vacuum rate of the vacuum assembly 800 is adjusted by detecting the secondary current, so that the vacuum environment above the molten pool in the vacuum welding chamber 100 can be more accurately controlled, thereby ensuring the smooth progress of the welding process and the welding penetration. After the welding is completed, closing the vacuum assembly 800 after the first preset time can properly maintain the vacuum environment in the vacuum welding chamber 100 during the cooling process of the weld, so as to avoid the weld from being oxidized by premature contact with air, which affects the quality of the weld joint.

[0064] Wherein, step S1 comprises:

[0065] Step S11: Processing an I-shaped groove on the base material 400 to be welded;

[0066] Step S12: Mechanically grinding the groove surface and the parent material within a certain range of the edge;

[0067] Step S13: using acetone and alcohol solvent to clean and remove oil stains;

[0068] Step S14 : assembling the base material 400 to be welded onto the supporting component 300 .

[0069] Through the above arrangement, the cleanliness of the area to be welded is ensured, which is helpful to obtain a qualified weld joint in subsequent welding. The certain range in step S12 refers to the range of 30 mm from the groove edge.

[0070] In step S4, the certain position above the molten pool refers to a position 5 to 15 cm above the molten pool, preferably 10 cm.

[0071] The above arrangement can accurately detect the vacuum environment state in a certain area above the molten pool, thereby facilitating more accurate control of the environment state of the welding area.

[0072] In step S4, controlling the air extraction rate of the air extraction component according to the relationship between the secondary current and the preset threshold value includes:

[0073] The detected secondary current is compared with a preset threshold value. When it is detected that the secondary current is greater than or equal to the preset threshold value, the pumping rate of the pumping component is increased. When it is detected that the secondary current is less than the preset threshold value, the pumping rate of the pumping component is maintained.

[0074] When it is detected that the secondary current is greater than or equal to the preset threshold, it means that under the influence of the plasma cloud and smoke above the molten pool, the vacuum degree near the molten pool is difficult to meet the requirements. In this case, the welding penetration depth is likely to become shallower and it is difficult to meet the requirements. At this time, increasing the exhaust rate of the exhaust assembly can increase the speed of extracting the plasma cloud and smoke, thereby reducing its impact on the laser beam, ensuring the welding penetration depth, and thus obtaining the required welding quality.

[0075] In step S5, the first preset time is 30-60 seconds, preferably 45 seconds.

[0076] It should be noted that the preset threshold value will vary depending on the material and thickness of the base material to be welded, and it is necessary to determine the preset threshold value of the secondary current corresponding to the base material under the corresponding parameters through preliminary vacuum laser welding tests. Example 3

[0077] This embodiment adopts the penetration stabilization device provided in Embodiment 1 and the welding method provided in Embodiment 2 to weld Ti80 titanium alloy plates for ships. The base material is 50 mm thick and the service environment of the base material has high requirements on impact toughness.

[0078] According to the previous vacuum laser welding test data, the preset threshold of the secondary current during vacuum laser welding of 50mm thick Ti80 titanium alloy was determined. During the welding process, the secondary current at a position 10cm above the molten pool was detected to adjust the exhaust rate of the exhaust assembly. During the welding process, the secondary current detection value was twice greater than or equal to the preset threshold. By increasing the exhaust rate of the exhaust assembly, the value of the secondary current was reduced, so that the penetration during the welding process was stable, and no incomplete penetration was found in the post-welding inspection. The penetration during the welding process was stable, and there was no nail tip defect in the welded joint. The X-ray flaw detection met the requirements of NB 47013-2015 Grade I. In addition, the penetration of the Ti80 titanium alloy joint obtained by the above welding method is about 3 times that of ordinary laser welding, and it has good mechanical properties, the tensile strength coefficient is above 0.95, and the impact absorption energy is higher than that of the parent material, as shown in Table 1.

[0079] Table 1 Comparison of vacuum laser welded Ti80 titanium alloy joint properties and parent material properties

[0080]

[0081] In addition to the welding thickness and performance being superior to those of normal pressure laser welding joints, the vacuum laser welding penetration stabilization device and method provided in this application can achieve efficient laser welding of large plate structures and ensure the stability of the penetration depth during vacuum laser welding, which has important significance and application prospects in the field of ships and deep-sea equipment.

[0082] It should be noted that all the terms used in the present invention for directional and positional indications, such as: "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "low", "tail end", "head end", "center", etc., are only used to explain the relative position relationship, connection status, etc. between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which both A and B are satisfied.

[0083] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0084] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A vacuum laser welding penetration stabilization device, characterized in that: Used in a vacuum laser welding system, the vacuum laser welding system comprising: A vacuum welding chamber (100) is used to form a vacuum welding environment on the surface of a parent material (400) to be welded; A laser welding gun (200) for generating a laser beam to weld a base material (400); A vacuum assembly (800) is used to vacuum the gas in the vacuum welding chamber (100) to form a vacuum welding environment; The penetration stabilization device comprises: a secondary current detection system and an exhaust control system (700), wherein the secondary current detection system is used to collect the potential difference between the parent material to be welded (400) and the welding smoke at a certain position above it, and obtain the secondary current according to the potential difference, and the exhaust control system (700) is used to control the exhaust rate of the exhaust component (800) according to the secondary current; The detected secondary current is compared with a preset threshold value. When it is detected that the secondary current is greater than or equal to the preset threshold value, the pumping rate of the pumping component is increased. When it is detected that the secondary current is less than the preset threshold value, the pumping rate of the pumping component is maintained.

2. The vacuum laser welding penetration stabilization device according to claim 1, characterized in that: The secondary current detection system comprises a load circuit (500) and an oscilloscope device (600); the load circuit (500) is used to detect the potential difference between a base material (400) to be welded and welding smoke at a certain position above the base material (400); the oscilloscope device (600) is used to detect the potential difference, calculate a corresponding secondary current based on the potential difference, transmit the secondary current to an exhaust control system (700), and display the secondary current in the form of a waveform; the exhaust control system (700) controls the exhaust rate of the exhaust assembly (800) based on the magnitude of the received secondary current.

3. The vacuum laser welding penetration stabilization device according to claim 2, characterized in that: The load circuit (500) comprises a secondary current collector (510) and a load resistor (520); the secondary current collector (510) is connected to a first end of the load resistor (520); the second end of the load resistor (520) is connected to a parent material (400) to be welded to form a loop; the oscilloscope device (600) is connected in parallel to the load resistor (520); the secondary current collector (510) is arranged in the vacuum welding chamber (100); its collection end is located at a certain position above the molten pool during welding; and the other end of the secondary current collector (510) is connected to the load resistor (520).

4. The vacuum laser welding penetration stabilization device according to claim 3, characterized in that: The collecting end of the secondary current collecting electrode (510) is located 5 to 15 cm above the molten pool.

5. The vacuum laser welding penetration stabilization device according to claim 3, characterized in that: The secondary current collecting electrode (510) is a thin copper plate.

6. The vacuum laser welding penetration stabilization device according to claim 2, characterized in that: The air extraction control system (700) comprises a comparison analysis module and a pumping speed control module. The comparison analysis module is in communication with the oscilloscope device (600) and is used to obtain the value of the secondary current and compare the value of the secondary current with a preset threshold value. The pumping speed control module is used to adjust the pumping rate of the air extraction component (800) according to the comparison result.

7. The vacuum laser welding penetration stabilization device according to any one of claims 1 to 6, characterized in that: The penetration stabilizing device can be used for stable control of weld penetration of one or two of titanium alloy, steel and aluminum alloy in vacuum laser welding.

8. A vacuum laser welding method with stable penetration, using a vacuum laser welding device with stable penetration as claimed in any one of claims 1 to 7, characterized in that: The welding method comprises: Step S1: Preparation before welding: Process the groove of the base material to be welded as required, and process its surface to meet the welding requirements, and then assemble it on the welding support component; Step S2: evacuating the vacuum welding chamber to make its vacuum degree meet the welding requirements; Step S3: After the vacuum degree meets the requirement, the laser welding gun is started to perform welding; Step S4: synchronously detecting the secondary current at a certain position above the molten pool during the welding process, and controlling the exhaust rate of the exhaust component according to the relationship between the secondary current and a preset threshold value; Step S5: After welding is completed, the laser welding gun is turned off, and after a first preset time, the exhaust assembly is turned off.

9. The vacuum laser welding method with stable penetration depth as claimed in claim 8, characterized in that: In step S4, controlling the air extraction rate of the air extraction component according to the relationship between the secondary current and the preset threshold value includes: The detected secondary current is compared with a preset threshold value. When it is detected that the secondary current is greater than or equal to the preset threshold value, the pumping rate of the pumping component is increased. When it is detected that the secondary current is less than the preset threshold value, the pumping rate of the pumping component is maintained.

10. The vacuum laser welding method with stable penetration depth as claimed in claim 8, characterized in that: In step S5, the first preset time is 30-60s.

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