An integrated apparatus and method for negative pressure laser welding and in-situ heat treatment of welds

Abstract

This invention relates to an integrated device and method for negative pressure laser welding and in-situ heat treatment of welds, belonging to the technical field of welding equipment. It includes a laser welding system, a negative pressure chamber, an internal environment control system, a workpiece motion drive system, a local heat treatment system for welds, a cooling system, and a control system. The laser beam output from the laser welding system enters the negative pressure chamber through a welding window. The local heat treatment system for welds includes an upper local heating unit and a lower heating fixture arranged inside the negative pressure chamber. The workpiece motion drive system is driven and connected to the lower heating fixture. The cooling system is used to maintain a stable temperature of the chamber walls. This invention solves the problem in the prior art where metal workpieces, after being welded using negative pressure laser welding, need to have the negative pressure removed before being transported to a heat treatment furnace for heat treatment, resulting in high time and cost. Furthermore, residual stress after welding can easily cause cracks and failure in the workpiece during cooling and transportation.

Description

Technical Field

[0001] This invention relates to an integrated device and method for negative pressure laser welding and in-situ heat treatment of welds, belonging to the technical field of welding equipment. Background Technology

[0002] With the rapid development of shipbuilding and marine engineering, nuclear energy equipment, aerospace and high-end energy equipment, thick plates and high-melting-point materials are increasingly being used as load-bearing structures in critical parts and as key structural components that are resistant to high temperatures, radiation, and erosion. Currently, the joining of thick plates and high-melting-point materials mainly employs processes such as gas inert gas welding (TIG), electron beam welding (EBW), and atmospheric pressure laser welding. TIG welding has a large heat input, and the weld and heat-affected zone are prone to grain coarsening and recrystallization softening, resulting in a significant decrease in the high-temperature performance of the joint. Although electron beam welding can achieve deep penetration welding under high negative pressure conditions, the equipment is expensive, sensitive to component size and clamping conditions, and has problems such as radiation and electromagnetic deflection, which is not conducive to its promotion in the manufacturing of thick plates and large complex components for ships. Atmospheric pressure laser welding has a high energy density, but when welding thick plate materials or refractory metals in an air environment, the interaction between the laser and the workpiece generates a large amount of plasma smoke and metal vapor plume, which has a shielding effect on the laser beam, resulting in a reduction in effective energy density and insufficient penetration. At the same time, the molten pool reacts with oxygen, nitrogen, and hydrogen in the atmosphere, which easily introduces pores, inclusions, and brittle phases, resulting in large dispersion in the performance of the welded joint.

[0003] To address the aforementioned issues, negative pressure (low negative pressure) laser welding technology has been proposed and applied to certain alloy materials. By reducing ambient pressure and using a protective gas, plasma plumes can be effectively suppressed, the effective energy density of the laser can be increased, and spatter and porosity defects can be reduced, making it suitable for welding thick plates and refractory metals. For example, when the ambient pressure is reduced to a low negative pressure of 10 Pa, the penetration depth of alloy negative pressure laser welding can even reach 2 to 3 times that in the atmospheric environment. In particular, the breakthroughs in high-power lasers in recent years have made negative pressure laser welding of ultra-thick alloys in the hundreds of millimeters range possible.

[0004] However, thick plates and high-melting-point materials often generate significant residual stress during welding. Post-weld heat treatment is typically used to release this stress. However, thick titanium alloys and refractory metals such as molybdenum, niobium, and tantalum are extremely sensitive to atmospheric elements like hydrogen and oxygen. If they are transferred to a heat treatment facility after welding as in the past, defects are easily generated during this process, and residual stress already exists in the weld, making disassembly of the workpiece highly susceptible to cracking. Chinese patent application CN118123235A discloses a combined negative pressure laser welding and heat treatment scheme, employing a large-volume negative pressure furnace or large negative pressure chamber to place the welding system and workpiece as a whole for welding and overall heating. This type of scheme is bulky, has a long evacuation time, poor adaptability to workpiece shape and size, and typically only uses unilateral heating, making it difficult to ensure temperature uniformity along the weld thickness. Furthermore, overall heating of the plate material easily causes unnecessary element diffusion, thus deteriorating performance.

[0005] Therefore, a device that is more efficient, ensures uniform temperature distribution in the weld, and performs heat treatment only on localized areas of the weld is needed.

[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present invention, and therefore may include information that does not constitute prior art. Summary of the Invention

[0007] The purpose of this invention is to provide a new technical solution to improve or solve the technical problems existing in the prior art as described above.

[0008] The technical solution provided by this invention is as follows: An integrated device for negative pressure laser welding and in-situ heat treatment of weld seams, comprising a laser welding system, a negative pressure chamber, an internal environment control system, a workpiece motion drive system, a local heat treatment system for weld seams, a cooling system, and a control system; the negative pressure chamber includes a chamber body and a cover covering the chamber body, the cover having a light-transmitting welding window; the laser welding system is disposed outside the negative pressure chamber, and the laser beam output by the laser welding system enters the interior of the negative pressure chamber through the welding window; the internal environment control system is disposed outside the negative pressure chamber. The chamber environment control system is used to evacuate the inside of the negative pressure chamber and introduce protective gas; the weld local heat treatment system includes an upper local heating unit and a lower heating fixture arranged inside the negative pressure chamber; the workpiece motion drive system is arranged inside the negative pressure chamber and drivenly connected to the lower heating fixture; the cooling system is used to maintain the chamber wall temperature of the negative pressure chamber is stable; the control system is electrically / signally connected to the laser welding system, the chamber environment control system, the workpiece motion drive system, the weld local heat treatment system and the cooling system respectively.

[0009] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention can realize high-quality single-pass welding of thick plate materials and refractory metals, and at the same time solves the technical problems in the prior art that after metal workpieces are welded by negative pressure laser welding, the negative pressure needs to be removed and then transported to the heat treatment furnace to remove the negative pressure for heat treatment, which is time-consuming and costly. At the same time, the workpieces are prone to cracking and failure due to residual stress after welding during cooling and transportation.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, a sealing structure is provided at the joint edge of the hatch cover and the cabin body. The sealing structure includes a high-temperature baffle, a high-temperature resistant sealing plate, and a double sealing strip arranged sequentially from the inside to the outside along the radial direction of the cabin body opening. The high-temperature baffle, the high-temperature resistant sealing plate, and the double sealing strip are all arranged circumferentially around the cabin body opening. The outer wall of the high-temperature baffle is in contact with the inner wall of the cabin body. One end of the high-temperature baffle is connected to the hatch cover, and the other end extends into the cabin body. One end of the high-temperature resistant sealing plate is connected to the hatch cover, and the other end is inserted into a groove opened at the end of the cabin body opening. The double sealing strip is provided on the end face of the cabin body opening, and its lower surface is in close contact with the double sealing strip when the hatch cover is closed.

[0012] The beneficial effect of adopting the above-mentioned further solution is that the sealing structure is composed of multiple seals arranged from the inside to the outside. The high-temperature baffle can first block the heat radiation inside the chamber and protect the outer sealing material; the high-temperature resistant sealing plate achieves the first mechanical seal by being inserted into the groove; and the outermost double sealing strip provides redundant airtightness assurance. The staged sealing significantly improves the long-term sealing reliability of the chamber under high temperature, high vacuum and temperature alternating conditions.

[0013] Furthermore, the hatch is also equipped with a sealing and leak detection device, which is connected to the sealing area between the double sealing strips and is used to detect the sealing performance.

[0014] The beneficial effect of adopting the above-mentioned further solution is that by setting up a sealing leak detection device, the sealing status can be monitored in real time or online, avoiding the interruption of the entire process, destruction of the protective atmosphere, or oxidation of the workpiece due to the failure of sealing failure to be detected in time, thereby improving the yield.

[0015] Furthermore, the hatch is also provided with a first water inlet and a first water outlet, which are respectively connected to the cooling system to provide a circulating cooling channel for the cooling medium.

[0016] The beneficial effect of adopting the above-mentioned further solution is that by setting independent first water inlet and first water outlet holes on the hatch cover, a separate circulating cooling channel is constructed between the hatch cover and the hull, and precise temperature control of the hatch cover is achieved through independent water circuit design. During high-temperature welding or heat treatment stages, it can prevent the hatch cover from affecting its sealing performance due to thermal deformation, and at the same time protect precision components such as laser windows and sensors installed on the hatch cover from heat damage, thus extending the service life of key components.

[0017] Furthermore, the welding window includes high-transparency glass, high-transparency high-temperature resistant glass, and a high-temperature resistant isolation plate arranged sequentially from the outside to the inside, and the high-temperature resistant isolation plate is movably mounted on the hatch cover.

[0018] The beneficial effects of adopting the above-mentioned further scheme are that the outer high-transparency glass ensures the high transmittance of the initial laser; the inner high-transparency high-temperature resistant glass directly faces the cabin environment and has better high-temperature resistance; the innermost movable high-temperature resistant isolation plate is opened during the welding stage and moved to the closed position during the heat treatment stage to isolate the heat radiation inside the cabin.

[0019] Furthermore, the inner wall of the negative pressure chamber is provided with a heat protection layer; the negative pressure chamber is also provided with a pressure sensor for monitoring internal pressure and a temperature sensor for monitoring internal temperature.

[0020] The beneficial effects of adopting the above-mentioned further solutions are that the thermal protection layer of the inner wall can directly reflect or absorb heat radiation, reducing the heat load transferred to the metal structure of the cabin, and working in conjunction with the external cooling system to ensure the structural integrity of the cabin. Pressure and temperature sensors enable real-time online monitoring of process environment parameters (pressure and temperature), providing feedback signals to the control system and ensuring the quality of welding and heat treatment.

[0021] Furthermore, the upper local heating unit includes an upper heating element, a primary heat insulation cover, a secondary heat insulation cover, and a robotic arm. The primary heat insulation cover is disposed inside the secondary heat insulation cover, the upper heating element is disposed inside the primary heat insulation cover, and the robotic arm is connected to the secondary heat insulation cover to drive the upper local heating unit to move above the weld and fit against or maintain a preset gap with the weld area.

[0022] The beneficial effect of adopting the above-mentioned further solution is that, through the double-layer heat insulation cover structure, the high temperature generated by the heating element is confined to a local area, reducing heat radiation to other parts of the cabin and reducing the environmental heat load. After the welding is completed, the robotic arm can move the upper local heating unit to the weld seam and flexibly adjust the distance with the workpiece or achieve the two to fit together, thereby meeting the local heat treatment requirements of complex weld seam trajectories or different workpiece shapes.

[0023] Furthermore, the lower heating fixture includes a clamping part for mounting or fixing the workpiece to be welded and a heating part for heating the weld area of ​​the workpiece. The heating part includes a lower heating element, a heat-conducting layer and an insulation layer. The heat-conducting layer is located on the working surface of the lower heating fixture. The lower heating element is disposed below or inside the heat-conducting layer. The insulation layer covers the periphery and bottom of the heating element.

[0024] The beneficial effects of adopting the above-mentioned further solution are that the lower heating fixture achieves heat conduction with the workpiece surface through the heat-conducting layer, ensuring uniform heating of the bottom of the weld; the insulation layer blocks the diffusion of heat to the non-working area of ​​the fixture, avoiding workpiece deformation or energy waste due to local overheating.

[0025] Furthermore, the upper local heating unit and / or the lower heating fixture are equipped with temperature detection elements.

[0026] The beneficial effect of adopting the above-mentioned further solution is that the temperature detection element can detect the temperature of the workpiece during the heat treatment process, and dynamically adjust the heating power after comparing it with the preset heat treatment curve, so as to achieve precise control of the temperature of the upper and lower surfaces of the weld.

[0027] A method for negative pressure laser welding and in-situ heat treatment of weld, utilizing the integrated device for negative pressure laser welding and in-situ heat treatment of weld, includes the following steps: S1. The workpiece to be welded is clamped on the lower heating fixture, and the chamber cover is closed to seal the negative pressure chamber. The chamber environment control system is used to evacuate the inside of the negative pressure chamber to a preset negative pressure range, and protective gas is introduced. At the same time, the cooling system is started. S2. Under the condition of maintaining the negative pressure and stable atmosphere, the control system controls the laser welding system to output a laser beam and controls the workpiece motion drive system to drive the workpiece to move along a preset trajectory to complete the welding. S3. After welding is completed, keep the workpiece in the negative pressure chamber and do not remove the negative pressure environment. Locally heat the weld area through the weld local heat treatment system. The upper local heating unit is moved to the top of the weld by a high-temperature resistant robotic arm, so that the heat-conducting surface of the upper local heating unit is in contact with the upper surface of the weld or maintains a preset gap. The heating part of the lower heating fixture is located below the weld. The upper local heating unit and the lower heating fixture are activated to heat the weld area together from top to bottom. S4. After the heat treatment is completed, restore the pressure inside the negative pressure chamber to normal pressure, open the chamber cover and take out the workpiece.

[0028] Compared with existing technologies, the technical solution provided by this invention has the following advantages: The processing method of this invention seamlessly integrates negative pressure laser welding and post-weld heat treatment within the same sealed, atmosphere-controlled negative pressure chamber. Directly initiating in-situ local heat treatment in the same environment eliminates intermediate steps such as post-weld workpiece cooling, transfer, secondary furnace loading, and re-vacuuming. This not only shortens the production cycle but also reduces the risk of workpiece cracking and failure during the high residual stress stage after welding through in-situ heat treatment, ensuring the overall quality and reliability of the workpiece. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 This is a three-dimensional structural schematic diagram of the integrated device for negative pressure laser welding and in-situ heat treatment of weld seams according to the present invention. Figure 2 This is a schematic diagram of the internal structure of the cabin of the present invention; Figure 3 This is a cross-sectional view of the cabin of the present invention; Figure 4 For the present invention Figure 3 Enlarged view of a portion at point A; Figure 5 This is a three-dimensional structural diagram of the upper local heating unit of the present invention; Figure 6 This is a schematic diagram of the structure of the primary heat insulation cover of the present invention; Figure 7 This is a schematic diagram of the sealing structure of the welding window of the present invention; Figure 8 This is a three-dimensional structural diagram of the lower heating fixture of the present invention; Figure 9 This is a partial cross-sectional view of the lower heating fixture of the present invention.

[0031] In the picture: 1. Negative pressure chamber; 101. Chamber body; 102. Chamber cover; 103. First water inlet; 104. First water outlet; 105. High-temperature baffle; 106. High-temperature resistant sealing plate; 107. Sealing strip; 108. Leak detection device; 109. High-transparency glass; 110. High-transparency high-temperature resistant glass; 111. High-temperature resistant isolation plate; 112. Thermal protection layer; 113. Second water inlet; 114. Second water outlet; 115. Temperature sensor; 2. Laser welding system; 3. In-cabin environment control system; 301. Air extraction port; 302. Air inlet port; 4. Workpiece motion drive system; 5. Upper local heating unit; 501. Upper heating element; 502. Primary heat insulation cover; 503. Secondary heat insulation cover; 504. Robotic arm; 6. Lower heating fixture; 601. Clamping part; 602. Lower heating element; 603. Heat-conducting layer; 604. Insulation layer. Detailed Implementation

[0032] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the objects described and do not imply any priority in order or any specific technical meaning. Furthermore, the concepts of "connection" and "linkage" mentioned in this application, unless otherwise specified, are considered to include both direct connection (linkage) and indirect connection (linkage).

[0033] When interpreting the description of this application, it should be clarified that terms such as "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating directions or positional relationships, are based on the perspective and layout shown in the accompanying drawings. They are intended to facilitate explanation and simplify the description process, and are not absolute limitations on the actual location, construction method, or operating mode of the described device or element. Therefore, these terms should not be construed as restrictive interpretations of the content of this application.

[0034] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0035] like Figure 1 and Figure 2As shown, an integrated device for negative pressure laser welding and in-situ heat treatment of weld seams includes a laser welding system 2, a negative pressure chamber 1, an internal environment control system 3, a workpiece motion drive system 4, a weld seam local heat treatment system, a cooling system, and a control system. The laser welding system 2 is located outside the negative pressure chamber 1. The negative pressure chamber 1 includes a chamber body 101 and a cover 102 covering the chamber body 101. The cover 102 has a light-transmitting welding window through which the laser beam output by the laser welding system 2 enters the interior of the negative pressure chamber 1. The internal environment control system 3 is located outside the negative pressure chamber 1 and is used to evacuate the interior of the negative pressure chamber 1 and introduce protective gas. The internal environment control system 3 includes a vacuum pump... The system includes an exhaust system and an intake system. The negative pressure chamber 1 is equipped with an exhaust port 301 connected to the exhaust system and an intake port 302 connected to the intake system. The weld local heat treatment system includes an upper local heating unit 5 and a lower heating fixture 6 arranged inside the negative pressure chamber 1. The workpiece motion drive system 4 is located inside the negative pressure chamber 1 and is drivenly connected to the lower heating fixture 6. The cooling system is used to maintain the stable temperature of the chamber wall of the negative pressure chamber 1. The control system is electrically / signally connected to the laser welding system 2, the chamber environment control system 3, the workpiece motion drive system 4, the weld local heat treatment system, and the cooling system, respectively, for coordinated control of the welding, negative pressure environment establishment and maintenance, cooling, and heat treatment processes. This invention enables high-quality single-pass welding of thick plate materials and refractory metals, while solving the technical problems in the prior art where metal workpieces need to have the negative pressure removed after welding with negative pressure laser welding and then transported to a heat treatment furnace for heat treatment, which is time-consuming and costly. In addition, the residual stress after welding can easily cause cracks in the workpiece during cooling and transportation, leading to failure.

[0036] More specifically, such as Figure 3 and Figure 4As shown, a sealing structure is provided at the joint edge of the hatch cover 102 and the cabin body 101. The sealing structure includes a high-temperature baffle 105, a high-temperature resistant sealing plate 106, and a double sealing strip 107 arranged sequentially from the inside to the outside along the radial direction of the opening of the cabin body 101. The high-temperature baffle 105, the high-temperature resistant sealing plate 106, and the double sealing strip 107 are all arranged circumferentially around the opening of the cabin body 101. The outer side wall of the high-temperature baffle 105 is in contact with the inner side wall of the cabin body 101. One end of the high-temperature baffle 105 is connected to the hatch cover 102, and the other end extends into the cabin body 101. One end of the high-temperature resistant sealing plate 106 is connected to the hatch cover 102, and the other end is inserted into the groove opened at the opening end of the cabin body 101. The double sealing strip 107 is provided on the end face of the opening end of the cabin body 101, and when the hatch cover 102 is closed, its lower surface is in close contact with the double sealing strip 107. The sealing structure consists of multiple seals arranged from the inside out. The high-temperature baffle 105 first blocks heat radiation from inside the chamber, protecting the outer sealing material; the high-temperature resistant sealing plate 106 achieves the first mechanical seal through an insertion groove; and the outermost double sealing strip 107 provides redundant airtightness assurance. This multi-stage sealing significantly improves the long-term sealing reliability of the chamber 101 under high temperature, high vacuum, and alternating temperature conditions. Both the high-temperature baffle 105 and the high-temperature resistant sealing plate 106 can withstand temperatures of 800-1000 degrees Celsius.

[0037] The hatch cover 102 is also equipped with a sealing leak detection device 108, which is connected to the sealing area between the double sealing strips 107. When the sealing strip 107 near the inner side cannot achieve a complete seal, the sealing leak detection device 108 will match the reading of the pressure gauge inside the cabin 101. Theoretically, the pressure value measured by the sealing leak detection device 108 should be lower than the pressure value inside the cabin 101 because the volume at that point is small and the seal is good. By setting up the sealing leak detection device 108, the sealing status can be monitored in real time or online, avoiding interruptions in the entire process, destruction of the protective atmosphere, or oxidation of the workpiece due to undetected sealing failure, thus improving the yield.

[0038] The cooling system includes a first circulating cooling channel disposed within the hatch cover 102 and a second circulating cooling channel disposed within the bulkhead of the cabin 101; both the first and second circulating cooling channels are provided with guide plates, which can directionally regulate the flow of coolant around the cabin 101 or the hatch cover 102 to achieve all-round cooling.

[0039] The hatch cover 102 is also provided with a first water inlet 103 and a first water outlet 104, which are connected to the first circulating cooling channel. The cabin body 101 is provided with a second water inlet 113 and a second water outlet 114, which are connected to the second circulating cooling channel. By setting independent first water inlet 103 and first water outlet 104 on the hatch cover 102, a separate circulating cooling channel is constructed between the hatch cover 102 and the cabin body 101. Precise temperature control of the hatch cover 102 is achieved through independent water circuit design. During high-temperature welding or heat treatment, the sealing performance of the hatch cover 102 can be prevented from being affected by thermal deformation, while protecting precision components such as laser windows and sensors installed on the hatch cover 102 from heat damage, thus extending the service life of key components.

[0040] The welding window includes, from the outside in, a high-transparency glass 109, a high-transparency high-temperature resistant glass 110, and a high-temperature resistant isolation plate 111, arranged sequentially from the outside in. The high-temperature resistant isolation plate 111 is movably mounted on the hatch cover 102. The outer high-transparency glass 109 ensures high transmittance of the initial laser. A double sealing strip 107 and a leak detection device 108 are provided between the outer high-transparency glass 109 and the hatch cover 102 (see reference). Figure 7 The inner high-transparency, high-temperature resistant glass 110 directly faces the cabin environment and has better high-temperature resistance; the innermost movable high-temperature resistant isolation plate 111 is opened during the welding stage and moved to the closed position during the heat treatment stage to isolate the cabin heat radiation.

[0041] In this embodiment, the high-transparency glass 109 can be made of quartz, allowing the laser to penetrate the bulkhead and enter the interior of the chamber 101. The high-transparency, high-temperature resistant glass 110, in addition to possessing the functions of the high-transparency glass 109, has stronger high-temperature resistance than the high-transparency glass 109 in order to withstand the high temperatures during the heat treatment stage; it can also be made of high-temperature resistant quartz. The high-temperature resistant isolation plate 111 is a high-temperature resistant plate that can be opened and closed via external control; it can be made of titanium alloy, and its function is to isolate the temperature below the high-transparency glass 109 during the heat treatment stage.

[0042] The inner wall of the negative pressure chamber 1 is provided with a thermal protection layer 112; the negative pressure chamber 1 is also equipped with a pressure sensor for monitoring internal pressure and a temperature sensor 115 for monitoring internal temperature. The thermal protection layer 112 on the inner wall can directly reflect or absorb heat radiation, reducing the heat load transferred to the metal structure of the chamber 101, and working in conjunction with the external cooling system to ensure the structural integrity of the chamber 101. The pressure sensor and temperature sensor 115 realize real-time online monitoring of process environment parameters (pressure, temperature), providing feedback signals to the control system and ensuring the quality of welding and heat treatment.

[0043] like Figure 5 andFigure 6 As shown, the upper local heating unit 5 includes an upper heating element 501, a primary heat insulation cover 502, a secondary heat insulation cover 503, and a robotic arm 504. The primary heat insulation cover 502 is disposed within the secondary heat insulation cover 503, and the upper heating element 501 is disposed within the primary heat insulation cover 502. The robotic arm 504 is connected to the secondary heat insulation cover 503 to drive the upper local heating unit 5 to move above the weld and to fit against or maintain a preset gap with the weld area. The primary heat insulation cover 502 and the secondary heat insulation cover 503 have through holes at their lower parts, through which the heat from the upper heating element 501 can be transferred to the weld. Furthermore, the double-layer heat insulation cover structure confines the high temperature generated by the heating element to a local area, reducing heat radiation to other parts of the chamber and lowering the environmental heat load. The robotic arm 504 can move the upper local heating unit 5 above the weld after welding is completed and flexibly adjust the distance to the workpiece or achieve fit, thereby meeting the local heat treatment requirements for complex weld trajectories or different workpiece shapes.

[0044] like Figure 8 and Figure 9 As shown, the lower heating fixture 6 includes a clamping part 601 for mounting or fixing the workpiece to be welded and a heating part for heating the weld area of ​​the workpiece. The heating part includes a lower heating element 602, a heat-conducting layer 603, and a heat-insulating layer 604. The heat-conducting layer 603 is located on the working surface of the lower heating fixture 6. The lower heating element 602 is disposed below or inside the heat-conducting layer 603. The heat-insulating layer 604 covers the periphery and bottom of the heating element. The lower heating fixture 6 achieves heat conduction with the workpiece surface through the heat-conducting layer 603, ensuring uniform heating of the bottom of the weld. The heat-insulating layer 604 blocks the diffusion of heat to the non-working area of ​​the fixture, avoiding workpiece deformation or energy waste due to local overheating.

[0045] The upper local heating unit 5 and / or the lower heating fixture 6 are equipped with temperature detection elements. These elements can detect the temperature of the workpiece during heat treatment, and dynamically adjust the heating power by feeding back the temperature data to the control system in real time. This adjustment is made after comparing the data with a preset heat treatment curve, thereby achieving precise control of the temperature of the upper and lower surfaces of the weld. The temperature detection elements are preferably thermocouples or infrared temperature sensors.

[0046] The present invention does not limit the type and structure of the workpiece motion drive system 4. The workpiece motion drive system 4 can adopt existing linear motion drive mechanisms, such as ball screw mechanisms, linear electric cylinder mechanisms or gear rack mechanisms, as long as they can realize the linear movement of the workpiece in the negative pressure chamber 1.

[0047] The present invention does not limit the type of the upper heating element 501 and the lower heating element 602. Resistance heating, induction heating or other heating elements can be used, as long as they can meet the needs of local heating of the weld area.

[0048] A method for negative pressure laser welding and in-situ heat treatment of weld, utilizing the integrated device for negative pressure laser welding and in-situ heat treatment of weld, includes the following steps: S1. The workpiece to be welded is clamped on the lower heating fixture 6, and the cover 102 is closed to seal the negative pressure chamber 1; the internal environment control system 3 is used to evacuate the inside of the negative pressure chamber 1 to a preset negative pressure range, and protective gas is introduced, while the cooling system is started. S2. Under the condition of maintaining the negative pressure and stable atmosphere, the control system controls the laser welding system 2 to output a laser beam and controls the workpiece motion drive system 4 to drive the workpiece to move along a preset trajectory to complete the welding. S3. After welding is completed, the workpiece is kept in the negative pressure chamber 1 and the negative pressure environment is not removed. The weld area is locally heated by the weld local heat treatment system. The upper local heating unit 5 is moved to the top of the weld by the high-temperature resistant robotic arm 504, so that the heat-conducting surface of the upper local heating unit 5 is in contact with the upper surface of the weld or maintains a preset gap. The heating part of the lower heating fixture 6 is located below the weld. The upper local heating unit 5 and the lower heating fixture 6 are activated to heat the weld area together from top to bottom. S4. After the heat treatment is completed, restore the pressure inside the negative pressure chamber 1 to normal pressure, open the chamber cover 102 and take out the workpiece.

[0049] The detailed process of negative pressure laser welding and in-situ heat treatment of weld seam in this invention is as follows: First, the metal workpiece to be welded is clamped on the clamping part 601 inside the negative pressure chamber 1, so that the workpiece is directly below the welding window, and the position parameters of the workpiece motion drive system 4 are adjusted to meet the weld trajectory requirements; at the same time, the bottom of the workpiece is positioned in the center of the lower heating fixture 6.

[0050] Subsequently, the cover 102 of the negative pressure chamber 1 is closed and sealed. The exhaust system is then activated to draw negative pressure from the chamber 101, reducing the internal pressure to a preset negative pressure range. Once the target pressure is reached, protective gas is introduced into the chamber through the air inlet 302 to establish a controllable protective atmosphere. Alternatively, a stable operating state of "adjustable negative pressure - controllable atmosphere" can be achieved through coordinated adjustment of exhaust and air intake. The internal pressure is monitored online and controlled in a closed loop using a pressure gauge or pressure sensor. Simultaneously, the cooling system is activated, introducing cooling medium into the flow channels built into the walls of the chamber 101 and the cover 102. This keeps the sealed area and critical structures of the chamber 101 within a safe temperature range, thereby inhibiting thermal aging of the sealing material and reducing the risk of structural thermal deformation.

[0051] After establishing the aforementioned environment, the control system sends welding process parameters to the laser welding system 2. The high-temperature resistant isolation plate 111 opens, the laser is activated, and the laser beam is emitted and incident on the workpiece surface through the welding window. Simultaneously, the workpiece motion drive system 4 controls the workpiece to move along the weld direction at a preset welding speed, achieving laser welding formation under negative pressure. During the welding process, the control system adjusts the exhaust and intake valves in real time based on pressure sensor feedback to maintain stable pressure and protective atmosphere within the chamber.

[0052] After welding is completed, the workpiece remains in the negative pressure chamber 1 without releasing the negative pressure environment. The control system switches to the post-weld local in-situ heat treatment mode. The upper local heating unit 5 of the weld local heat treatment system is moved above the weld area by a high-temperature resistant robotic arm 504, ensuring that its heat-conducting surface is in contact with the area to be heat-treated or maintains a preset gap. The upper local heating unit 5 and the lower heating fixture 6 provide coordinated heating to the weld area from both above and below, using resistance heating, induction heating, or other heating elements to raise and maintain the temperature of the local weld area. Temperature detection elements collect temperature signals of the weld and its adjacent areas in real time. The control system performs closed-loop adjustment of the heating power according to the set heat treatment curve, ensuring that the local weld area reaches the preset heat treatment temperature and is maintained at the preset holding time to achieve residual welding stress release, microstructure stabilization, or performance improvement. During the heat treatment stage, the cooling system continues to operate to thermally manage the structure of the chamber 101; the exhaust system and intake system maintain the target pressure and atmosphere to prevent weld performance degradation due to oxidation or contamination during the heat treatment process.

[0053] Finally, after heat preservation and controlled cooling are completed, local heating is stopped, and the pressure inside the chamber is slowly increased to atmospheric pressure or the set pressure through the air inlet valve. The chamber cover 102 is then opened to remove the workpiece, completing the integrated process of negative pressure laser welding and post-weld local in-situ heat treatment of the weld. This process avoids the multiple transfers and repeated negative pressure extraction steps required after welding, such as releasing the negative pressure and transporting the workpiece to a heat treatment furnace for re-evacuation, thus reducing time and costs. Furthermore, in-situ heat treatment during the high residual stress stage after welding reduces the risk of cracking and failure of the workpiece.

[0054] The processing method of this invention seamlessly integrates negative pressure laser welding and post-weld heat treatment within the same sealed, atmosphere-controlled negative pressure chamber 1. Directly initiating in-situ local heat treatment in the same environment eliminates intermediate steps such as post-weld workpiece cooling, transfer, secondary furnace loading, and re-vacuuming. This not only shortens the production cycle but also reduces the risk of workpiece cracking and failure during the high residual stress stage after welding through in-situ heat treatment, ensuring the overall quality and reliability of the workpiece.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated device for negative pressure laser welding and in-situ heat treatment of weld seams, characterized in that, It includes a laser welding system (2), a negative pressure chamber (1), an internal environment control system (3), a workpiece motion drive system (4), a weld local heat treatment system, a cooling system, and a control system; the negative pressure chamber (1) includes a chamber body (101) and a cover (102) covering the chamber body (101), and the cover (102) is provided with a light-transmitting welding window; The laser welding system (2) is located outside the negative pressure chamber (1), and the laser beam output by the laser welding system (2) can enter the interior of the negative pressure chamber (1) through the welding window; The cabin environment control system (3) is located outside the negative pressure chamber (1). The cabin environment control system (3) is used to evacuate the inside of the negative pressure chamber (1) and introduce protective gas. The local heat treatment system for welds includes an upper local heating unit (5) and a lower heating fixture (6) arranged inside the negative pressure chamber (1). The workpiece motion drive system (4) is located inside the negative pressure chamber (1) and is driven by the lower heating fixture (6); The cooling system is used to maintain a stable temperature of the bulkhead of the negative pressure chamber (1); The control system is electrically / signally connected to the laser welding system (2), the cabin environment control system (3), the workpiece motion drive system (4), the weld local heat treatment system, and the cooling system, respectively.

2. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to claim 1, characterized in that, A sealing structure is provided at the joint edge of the hatch cover (102) and the cabin body (101). The sealing structure includes a high-temperature baffle (105), a high-temperature resistant sealing plate (106), and a double sealing strip (107) arranged sequentially from the inside to the outside along the radial direction of the opening of the cabin body (101). The high-temperature baffle (105), the high-temperature resistant sealing plate (106), and the double sealing strip (107) are all arranged circumferentially around the opening of the cabin body (101). The outer wall of the high-temperature baffle (105) is flush with the cabin body (101). 1) The inner sidewalls are fitted together. One end of the high temperature baffle (105) is connected to the hatch cover (102), and the other end extends into the interior of the cabin body (101). One end of the high temperature resistant sealing plate (106) is connected to the hatch cover (102), and the other end is inserted into the groove opened at the opening end of the cabin body (101). The double sealing strip (107) is set on the end face of the opening end of the cabin body (101). When the hatch cover (102) is closed, its lower surface is tightly fitted with the double sealing strip (107).

3. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to claim 2, characterized in that, The hatch cover (102) is also provided with a sealing and leak detection device (108), which is connected to the sealing area between the double sealing strip (107) and is used to detect the sealing performance.

4. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to claim 1, characterized in that, The hatch (102) is also provided with a first water inlet (103) and a first water outlet (104). The first water inlet (103) and the first water outlet (104) are respectively connected to the cooling system to provide a circulating cooling channel for the cooling medium.

5. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to claim 1, characterized in that, The welding window includes a high-transparency glass (109), a high-transparency high-temperature resistant glass (110), and a high-temperature resistant isolation plate (111) arranged sequentially from the outside to the inside. The high-temperature resistant isolation plate (111) is movably arranged on the hatch cover (102).

6. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to claim 1, characterized in that, The inner wall of the negative pressure chamber (1) is provided with a heat protection layer (112); the negative pressure chamber (1) is also provided with a pressure sensor for monitoring the internal pressure and a temperature sensor for monitoring the internal temperature (115).

7. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to any one of claims 1-6, characterized in that, The upper local heating unit (5) includes an upper heating element (501), a primary heat insulation cover (502), a secondary heat insulation cover (503), and a robotic arm (504). The primary heat insulation cover (502) is disposed inside the secondary heat insulation cover (503). The upper heating element (501) is disposed inside the primary heat insulation cover (502). The robotic arm (504) is connected to the secondary heat insulation cover (503) to drive the upper local heating unit (5) to move above the weld and fit against or maintain a preset gap with the weld area.

8. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to any one of claims 1-6, characterized in that, The lower heating fixture (6) includes a clamping part (601) for mounting or fixing the workpiece to be welded and a heating part for heating the weld area of ​​the workpiece. The heating part includes a lower heating element (602), a heat-conducting layer (603) and an insulation layer (604). The heat-conducting layer (603) is located on the working surface of the lower heating fixture (6). The lower heating element (602) is disposed below or inside the heat-conducting layer (603). The insulation layer (604) covers the periphery and bottom of the heating element.

9. The integrated device for negative pressure laser welding and in-situ heat treatment of weld seam according to claim 7, characterized in that, The upper local heating unit (5) and / or the lower heating fixture (6) are equipped with temperature detection elements.

10. A method for negative pressure laser welding and in-situ heat treatment of the weld, characterized in that, The integrated device for negative pressure laser welding and in-situ heat treatment of weld as described in any one of claims 1 to 9 includes the following steps: S1. The workpiece to be welded is clamped on the lower heating fixture (6), and the cover (102) is closed to seal the negative pressure chamber (1). The chamber environment control system (3) is used to evacuate the inside of the negative pressure chamber (1) to a preset negative pressure range and introduce protective gas. At the same time, the cooling system is started. S2. Under the condition of maintaining the negative pressure and stable atmosphere, the control system controls the laser welding system (2) to output a laser beam and controls the workpiece motion drive system (4) to drive the workpiece to move along a preset trajectory to complete the welding. S3. After welding is completed, keep the workpiece in the negative pressure chamber (1) and do not release the negative pressure environment. Locally heat the weld area through the weld local heat treatment system. The upper local heating unit (5) is moved above the weld by a high-temperature resistant robotic arm (504), so that the heat-conducting surface of the upper local heating unit (5) is in contact with the upper surface of the weld or maintains a preset gap. The heating part of the lower heating fixture (6) is located below the weld. The upper local heating unit (5) and the lower heating fixture (6) are activated to heat the weld area together from top to bottom. During the heat treatment stage, the cooling system continues to work to cool and protect the cabin (101). S4. After the heat treatment is completed, stop heating, restore the pressure in the negative pressure chamber (1) to normal pressure, open the chamber cover (102) and take out the workpiece.

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