A welding robot and its welding residual stress monitoring system

Abstract

The present invention belongs to the technical field of welding equipment, and particularly relates to a welding robot and its welding residual stress monitoring system, including a robot body and a welding module installed at the free end of the robot body; wherein, the welding module includes: a focusing and reflecting module fixedly installed on a fixed support, a water-cooled outer frame for cooling the lens is arranged at the bottom of the focusing and reflecting module, a coupling reflecting lens barrel is installed on one side of the focusing and reflecting module, and a laser and a thermal imaging temperature monitor are installed on the coupling reflecting lens barrel; a heat conducting plate, a butt joint section is provided on the opposite side, and the butt joint section is used for relatively splicing and blocking between the welding workpiece and the pre-adjusted laser beam to preheat the welding workpiece. The present invention can preheat and slow down the cooling of the welding position during the welding process, thereby effectively reducing the generation of prestress and residual stress, and continuously monitoring the temperature of the workpiece at the welding position to monitor the welding stress state of the workpiece.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding equipment, and particularly relates to a welding robot and its welding residual stress monitoring system. Background Art

[0002] A laser welding robot uses a semiconductor laser as the welding heat source, and locally heats the workpiece through a laser beam to achieve an automated welding device. Its principle is to utilize the high energy density of the laser to rapidly melt and solidify the welding part to form a firm weld seam. It mainly consists of the following parts:

[0003] The robot body is the basic component unit of the laser welding robot, responsible for the movement and positioning of the robot.

[0004] The laser is the core component of the laser welding robot, responsible for generating a high-energy and highly focused laser beam. The laser beam is transmitted to the workpiece through the focusing and reflecting module, melting and solidifying the workpiece locally, thereby achieving welding.

[0005] The focusing and reflecting module is a key component on the robot arm, responsible for transmitting the laser beam to the workpiece and adjusting the angle and position of the laser beam.

[0006] The control system is the brain of the laser welding robot, responsible for controlling the movement of the robot, the output of the laser, and the position and angle of the focusing and reflecting module, etc.

[0007] The sensor is the sensory organ of the laser welding robot, used to sense information such as the position, shape, and size of the workpiece, as well as parameters such as temperature and pressure during the welding process. The sensor feeds this information back to the control system, and the control system adjusts the movement of the robot and the welding parameters according to this information to ensure the welding quality and efficiency.

[0008] However, although the existing laser welding robots are already very advanced, there are still certain problems in the actual application process, especially in terms of the control of welding stress:

[0009] 1. The high-temperature characteristics of the welded workpiece and laser welding result in a lot of prestress and residual stress during the laser welding process. This welding stress is not well controlled, reducing the stability of the welding structure at the welding position and possibly causing cracks or fractures at the welding position.

[0010] 2. To protect the welding position, inert gas is blown at the welding position during the welding process to protect it, prevent oxidation, and clean the slag and dust generated by welding. However, the blowing method generally blows directly at the welding position. Although it can play a protective role, it only uses inert gas to accelerate gas flow and does not form an effective protection circle. At the same time, it will accelerate the cooling of the welding position, resulting in an increase in residual stress. Summary of the Invention

[0011] The object of the present invention is to provide a welding robot and its welding residual stress monitoring system, which can preheat and slow down the cooling of the welding position during the welding process, thereby effectively reducing the generation of prestress and residual stress, and continuously monitoring the temperature of the workpiece at the welding position to monitor the welding stress state of the workpiece.

[0012] The technical solutions adopted by the present invention are specifically as follows:

[0013] A welding robot includes a robot body and a welding module installed at the free end of the robot body;

[0014] Among them, the welding module includes:

[0015] A fixed support fixedly connected to the free end of the robot body, and an L-shaped support plate is vertically and liftably installed on the fixed support;

[0016] A focusing and reflecting module fixedly installed on the fixed support, a water-cooled outer frame for cooling the lens is provided at the bottom of the focusing and reflecting module, a coupling reflecting barrel is installed on one side of the focusing and reflecting module, and a laser for emitting laser and a thermal imaging temperature monitor for detecting the temperature of the welding workpiece are installed on the coupling reflecting barrel;

[0017] A swing support rotatably installed at the bottom of the L-shaped support plate, and an L-shaped arm is slidably installed facing the side of the swing support;

[0018] A heat conduction plate fixedly installed at the bottom of the L-shaped arm, a docking cut surface is provided on the opposite side of the heat conduction plate, and the welding workpiece is preheated by using the docking cut surface to be spliced and blocked between the welding workpiece and the pre-adjusted laser beam. Liquid inlet ports and liquid outlet ports are respectively provided at both ends of the heat conduction plate, and a fluid channel communicating the liquid inlet port and the liquid outlet port is opened inside it, so as to slow down the cooling of the welding position by connecting the circulating cooling liquid of the water-cooled outer frame through the liquid inlet port and passing through the fluid channel.

[0019] As a preferred solution, a lifting mechanism for driving the L-shaped support plate to vertically lift and lower is arranged between the fixed support and the L-shaped support plate, and includes a first micro servo motor fixedly mounted on the top surface of the fixed support, a first lead screw rotatably mounted on the fixed support, and a first nut slide threadedly connected to the first lead screw. The power output end of the first micro servo motor is connected to the first lead screw through a reducer. A limiting support rod is symmetrically fixedly mounted on the fixed support parallel to the first lead screw. A limiting slide is slidably mounted on the limiting support rod. The L-shaped support plate is fixedly mounted on the first nut slide and the limiting slide.

[0020] As a preferred solution, the L-shaped support plate is provided with a mounting through hole which coincides with the central axis of the lens of the focusing reflective module; a connecting seat is integrally formed on the top surface of the swivel support and is rotatably installed in the mounting through hole; a ring-shaped light source for fill light is fixedly installed at the center of the connecting seat; a turnover mechanism is provided between the connecting seat and the L-shaped support plate for driving the swivel support to rotate circumferentially relative to the L-shaped support plate.

[0021] As a preferred solution, the turnover mechanism includes a second micro servo motor fixedly mounted on the L-shaped support plate, a driving gear connected to the power output end of the second micro servo motor through a reducer, and a driven gear fixedly sleeved on the outer surface of the connecting seat, and the driving gear is meshed with the driven gear.

[0022] As a preferred solution, a third micro servo motor is fixedly installed at the center of the side surface of the swivel support, and the swivel support is symmetrically provided with sliding grooves on both sides of the third micro servo motor. A second nut slide is slidably installed inside the slide groove, and the power output end of the third micro servo motor is connected to a second lead screw through a dual-axis reducer for opposite transmission. The inner side of the second nut slide is threadedly connected to the second lead screw, and the outer side is fixedly connected to the L-shaped support arm.

[0023] As a preferred solution, the butt-joint surface is a vertical butt-joint surface or an inclined butt-joint surface, and the inclination angle is 15°-60°.

[0024] As a preferred solution, a buffer chamber is fixedly installed on one end of the heat conduction plate close to the liquid inlet port, and the buffer chamber is provided with an air inlet port for connecting to blow protective gas. A gas outlet groove perpendicular to it is opened on the butt cut surface, and the gas outlet groove is connected with the buffer chamber to blow protective gas to the welding position.

[0025] As a preferred solution, a gas guiding component for changing the gas flow direction is installed in the air outlet groove. The gas guiding component includes gas guiding pipes symmetrically arranged at both ends of the air outlet groove, a V-shaped elastic plate integrally formed between the butt ends of the gas guiding pipes, and a positioning shaft fixedly installed in the middle of the air outlet groove. A V-shaped groove is formed between the gas guiding pipes and the V-shaped elastic plate, and the positioning shaft is embedded in the V-shaped groove. An elastic connecting pipe for connecting them to each other is arranged between the butt end faces of the gas guiding pipes.

[0026] As a preferred solution, two groups of the gas guiding components arranged oppositely are both communicated with the matching air buffer bin, and the gas flow directions between the two are set in reverse, so as to form a spiral air flow connected end to end when deforming to protect the welding position.

[0027] A welding residual stress monitoring system for a welding robot, which is applied to the above-mentioned welding robot, includes:

[0028] A stress temperature acquisition module, which uses a thermal imaging temperature monitor to monitor the initial temperature, preheating temperature, welding temperature and residual temperature at the welding position in real time, and uses the collected temperature values to conduct a comparative analysis with the preset welding stress range;

[0029] A welding preheating module, which emits preheating laser through a laser, a coupling reflecting mirror tube and a focusing reflecting module, and irradiates the preheating laser on a heat conducting plate to preheat a workpiece to be welded in contact therewith. At the same time, the welding laser power is adjusted to reach the required power for welding, and a thermal imaging temperature monitor is used to monitor the preheating temperature of the workpiece to be welded until the required temperature range is reached;

[0030] A welding stress monitoring module, which obtains the actual temperature at the welding position of the workpiece and the temperature value of the welding laser during the welding process through a thermal imaging temperature monitor, and conducts a comparative analysis on the two groups of collected temperature values, conducts a comparative analysis with the preset welding temperature rising range, obtains the temperature rising state of the workpiece, and conducts a comparative analysis with the preset welding stress range according to the temperature rising state to obtain the welding stress state;

[0031] A welding slow cooling module, which connects the heated circulating cooling liquid of the water-cooled outer frame body through a liquid inlet port, and insulates the welding position through a fluid channel to achieve the purpose of slow cooling. At the same time, a thermal imaging temperature monitor is used to monitor the temperature value during the slow cooling of the welded workpiece, and a comparative analysis is conducted according to the temperature value and the preset welding stress range to obtain the residual stress state.

[0032] The technical effects achieved by the present invention are:

[0033] The present invention is made of a heat conduction plate and a heat conduction material. Before welding a workpiece, the laser that is not fully focused during the welding laser process can be used to preheat the workpiece that is in contact with it. At the same time, during the preheating process, the position between it and the laser lens can be continuously adjusted to control the preheating temperature, ensuring that the laser preheats the workpiece without damaging its surface, reducing the welding prestress, ensuring the smooth progress of welding, and improving the welding quality.

[0034] The present invention is provided with a liquid inlet port, a liquid outlet port, and a fluid channel on the heat conduction plate in cooperation. During the welding process, the heated coolant after welding can be used to slowly cool the welded part of the welded workpiece, reducing its cooling speed, thereby reducing the generation of residual stress, improving the welding quality, and avoiding cracks or fractures caused by too fast cooling after welding.

[0035] The present invention is provided with a slow gas storage chamber and an air inlet port on the heat conduction plate, which cooperate with a gas guiding component. When the heat conduction plates are spliced relatively, the gas guiding component is hidden inside the heat conduction plate. When it is unfolded to weld the workpiece, the air guide pipes are simultaneously unfolded in a V shape under the action of the elastic force of the V-shaped elastic plate, and the two groups of gas guiding components are arranged relatively to form a diamond-shaped frame, surrounding the welding position, and using the criss-crossing and relatively flowing airflows to form a spiral airflow to completely surround and protect the welding position, forming a spiral protection layer, isolating the welding position from the outside world. While avoiding oxidation, cleaning of slag and dust at the welding position, it does not form a situation of direct airflow blowing, can slow down the temperature drop at the welding position, reduce the generation of residual stress, and thus ensure the stability of the welding structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a three-dimensional structural schematic diagram of an embodiment of the present invention;

[0037] Figure 2 is a three-dimensional structural schematic diagram of a welding module in an embodiment of the present invention;

[0038] Figure 3 is the present invention Figure 2 exploded view;

[0039] Figure 4 is a three-dimensional structural schematic diagram of the other side of the welding module in an embodiment of the present invention;

[0040] Figure 5 is the present invention Figure 3 partial exploded view;

[0041] Figure 6 is a combined side view of a swing support and a heat conduction plate in an embodiment of the present invention;

[0042] Figure 7It is the unfolded state diagram of the combination of the swing support and the heat conduction plate in the embodiment of the present invention;

[0043] Figure 8 It is another view of the unfolded state of the combination of the swing support and the heat conduction plate in the embodiment of the present invention;

[0044] Figure 9 It is the schematic diagram of the state change of the air guiding component in the embodiment of the present invention;

[0045] Figure 10 It is the schematic structural diagram of the air guiding component in the unfolded state in the embodiment of the present invention;

[0046] Figure 11 It is the present invention Figure 10 The enlarged view of the partial area A therein;

[0047] Figure 12 It is the schematic structural diagram of the heat conduction plate in the embodiment of the present invention;

[0048] Figure 13 It is the sectional view of the heat conduction plate in the embodiment of the present invention;

[0049] Figure 14 It is the schematic structural diagram of the welding residual stress monitoring system in the embodiment of the present invention.

[0050] In the drawings, the list of components represented by each reference numeral is as follows:

[0051] 100, robot body;

[0052] 200, welding module;

[0053] 1, fixed support;

[0054] 11, L-shaped support plate; 12, first micro servo motor; 13, first lead screw; 14, first nut slider; 15, limit support rod; 16, limit slider; 17, installation through hole; 18, second micro servo motor; 19, driving gear;

[0055] 2, focusing reflection module;

[0056] 21, water-cooled outer frame; 22, coupling mirror barrel; 23, thermal imaging temperature monitor; 24, laser; 25, CCD camera;

[0057] 3, swing support;

[0058] 31, connecting seat; 32, L-shaped arm; 33, annular light source; 34, driven gear; 35, third micro servo motor; 36, double-axis reducer; 37, chute; 38, second nut slider; 39, second lead screw;

[0059] 4, heat conduction plate;

[0060] 41. Liquid inlet port; 42. Liquid outlet port; 43. Air buffer chamber; 44. Air inlet port; 45. Docking section; 46. Air outlet groove; 47. Fluid channel;

[0061] 5. Air guiding assembly;

[0062] 51. Air guiding pipe; 52. V-shaped elastic plate; 53. Positioning shaft; 54. Elastic connecting pipe. Specific embodiments

[0063] In order to make the objectives and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or several specific implementation manners of the present invention, and does not strictly limit the scope of protection specifically claimed by the present invention.

[0064] As Figures 1 - 13 shown, a welding robot includes a robot body 100 and a welding module 200 installed at the free end of the robot body 100.

[0065] Referring to the attached Figure 1 , wherein, in this embodiment, the robot body 100 is a 6-axis articulated manipulator driven by a servo motor, and is composed of a driver, a transmission mechanism, a robotic arm, joints, and internal sensors, etc. These components work together to ensure that the welding module 200 installed at the free end of the manipulator can accurately reach the specified position, maintain the correct posture, and perform welding operations according to the predetermined motion trajectory.

[0066] Of course, in other embodiments, the robot body 100 can select robot devices with different degrees of freedom according to needs to meet production requirements.

[0067] Referring to the attached Figures 2 - 3 , wherein, the welding module 200 includes a fixed support 1 fixedly connected to the free end of the robot body 100, a focusing and reflecting module 2 fixedly installed on the fixed support 1, a swinging support 3 rotatably connected to the fixed support 1, and a heat guiding plate 4 slidably connected to the swinging support 3 in an opposing manner; the fixed support 1 provides stable support for other components, and at the same time, the swinging support 3 can rotate relative to the focusing and reflecting module 2 to drive the heat guiding plate 4 to follow the welding movement direction, and then preheat, slow cool the workpiece and provide blowing protection during the welding process through the heat guiding plate 4.

[0068] Referring to the attached Figures 3 - 4A water-cooled outer frame 21 for cooling the lens is provided at the bottom of the focusing and reflecting module 2, and a water inlet and outlet are provided on the water-cooling frame to connect the water-cooling liquid inlet pipe and the liquid outlet pipe, and the welding lens is cooled by circulating water-cooling liquid; at the same time, a coupling reflecting lens barrel 22 is installed on one side of the focusing and reflecting module 2, and a laser 24 for emitting laser is installed on the coupling reflecting lens barrel 22 through a collimating focusing lens, and a thermal imaging temperature monitor 23 for detecting the temperature of the welding workpiece is installed through an inclined bracket, and a CCD camera 25 is installed on the other side of the coupling reflecting lens barrel 22, laser is output through the laser 24, and the collimating focusing lens is used to cooperate with the focusing and reflecting module 2 to focus the output laser beam into a laser spot, and the CCD camera 25 is used to cooperate with the coupling reflecting lens barrel 22 and the focusing and reflecting module 2 to find the welding point, so as to achieve precise welding of the workpiece.

[0069] See attached Figure 5 In order to adjust the distance between the swing support 3 and the lens of the focusing reflection module 2, the top surface of the fixed support 1 includes a first micro servo motor 12 fixedly installed, and a first lead screw 13 is rotatably installed on the fixed support 1, and a first nut slide 14 is threadedly connected to the first lead screw 13. The power output end of the first micro servo motor 12 is connected to the first lead screw 13 through a reducer transmission, and a limit support rod 15 is fixedly installed on the fixed support 1 in parallel and symmetrically with the first lead screw 13, and a limit slide 16 is slidably installed on the limit support rod 15. The L-shaped support plate 11 is fixedly installed using the first nut slide 14 and the limit slide 16. After the adjustment swing support 3 is connected to the L-shaped support plate 11, the first micro servo motor 12 drives the first lead screw 13 to rotate, so that the first nut slide 14 can move up and down along its surface, thereby driving the swing support 3 and the L-shaped support plate 11 to move up and down, thereby realizing the adjustment of the distance between the lens of the focusing reflection module 2.

[0070] Of course, in other embodiments, the distance between the pendulum support 3 and the lens of the focusing reflection module 2 can be adjusted by vertically installing a cylinder or an electric telescopic rod on the fixed support 1, fixing the L-shaped support plate 11 at its power output end, and connecting the adjustable pendulum support 3 to the L-shaped support plate 11. This can be selected according to actual production needs.

[0071] Again refer to the attached Figure 5In order to enable the swivel support 3 to rotate on the installation plane compared to the L-shaped support plate 11, a mounting through hole 17 that coincides with the central axis of the lens of the focusing and reflecting module 2 is opened on the L-shaped support plate 11. At the same time, a connecting seat 31 is integrally formed on the top surface of the swivel support 3, and is rotatably installed in the mounting through hole 17 using a bearing, so that the laser beam can pass through the mounting through hole 17 and the central axis of the swivel support 3, avoiding obstruction of the laser beam and affecting the welding operation; at the same time, a ring light source 33 for fill light is fixedly installed in the center of the connecting seat 31, so that the ring light source 33 can be adjusted in height compared to the lens of the focusing and reflecting module 2. Due to the setting of the ring structure, the fill light range will not be affected during the rotation process.

[0072] Furthermore, a second micro servo motor 18 is fixedly mounted on the L-shaped support plate 11, and a driving gear 19 is connected to the power output end of the second micro servo motor 18 through a reducer transmission, and a driven gear 34 is fixedly sleeved on the outer surface of the connecting seat 31. By meshing the driving gear 19 with the driven gear 34, the second micro servo motor 18 can be used to drive the driving gear 19 to rotate, thereby driving the swing support 3 to rotate relative to the installation plane of the L-shaped support plate 11.

[0073] Of course, in other embodiments, the purpose of driving the swing support 3 to rotate relative to the installation plane of the L-shaped support plate 11 can be achieved by installing a worm gear transmission between the connecting seat 31 and the installation through hole 17, or other existing annular driving methods can be used.

[0074] See attached Figures 5 - 8, on the side of the swing support 3, an L-shaped arm 32 is slidably installed facing each other, and the heat conduction plate 4 is fixedly installed at the bottom of the L-shaped arm 32, so that the two groups of heat conduction plates 4 can move relative to each other to achieve docking and separation. Thus, before welding, the preheating laser is emitted by the laser 24, the coupling mirror tube 22 and the focusing reflection module 2, and irradiated on the butt-jointed heat conduction plates 4. At the same time, the heat conduction plate 4 is attached to the surface of the workpiece to be welded, blocking the welding laser. Under the action of the welding laser, it is gradually heated, and at the same time, the workpiece to be welded in contact with it is preheated. During this process, the power of the welding laser can be adjusted to reach the required welding power. And in order not to damage the heat conduction plate 4 by the emitted laser beam, the height of the L-shaped support plate 11 can be adjusted by the first micro servo motor 12 through the first lead screw 13 and the first nut slider 14, and then the distance between the heat conduction plate 4 and the lens of the focusing reflection module 2 is adjusted, so that the laser beam will not be completely focused on a certain point, that is, the heat conduction plate 4 is heated, and at the same time, its surface will not be damaged; and during the preheating process, the preheating temperature of the workpiece to be welded is monitored by the thermal imaging temperature monitor 23 until the required temperature range is reached. In this way, the workpiece temperature is adapted to the welding temperature, which can greatly reduce the prestress caused by the welding temperature difference, thereby improving the stability of the welding structure and ensuring the welding quality.

[0075] It should be noted that the heat conduction plate 4 should be made of materials with high thermal conductivity and electrical conductivity such as copper, aluminum, steel, titanium and their alloys. In this way, it can effectively absorb laser energy and quickly conduct heat, so that it can block the laser beam and at the same time conduct heat to preheat the workpiece to be welded; in this embodiment, the heat conduction plate 4 is made of titanium alloy material, and its melting point is about 1668°C. In this way, it will not be damaged by the laser when welding general metals, and at the same time, its excellent heat resistance and corrosion resistance can ensure its working stability.

[0076] Furthermore, in order to enable the two groups of heat conduction plates 4 to be stably docked, a docking section 45 is provided on the opposite side of the heat conduction plate 4, and the docking section 45 is used to block and splice relatively between the welding workpiece and the pre-adjusted laser beam to preheat the welding workpiece. The docking section 45 can be a vertical docking surface or an inclined docking surface. If it is an inclined docking surface, the inclination angle can be set to 15°-60°.

[0077] In this embodiment, the docking section 45 selects a 30° inclined section on the opposite side, so that they can cross and splice with each other during docking, and the docking is more stable. At the same time, since the docking gap is not in the center position, the laser beam will not directly irradiate on the docking gap, avoiding damage to the heat conduction plate 4 through the docking gap, and thus reducing the damage to it.

[0078] When the preheating temperature of the workpiece to be welded reaches the required temperature range, it is necessary to separate the two sets of butt-jointed heat conduction plates 4 from each other so that the laser beam can pass through the gap between them to weld the workpiece. To achieve this purpose:

[0079] Refer to the appendix again Figures 5 - 8 , a third micro servo motor 35 is fixedly installed at the center of the side surface of the swing support 3, and sliding grooves 37 are symmetrically arranged on both sides of the third micro servo motor 35 on the swing support 3. At the same time, a second nut slider 38 is slidably installed inside the sliding groove 37. A second lead screw 39 is connected in a counter-directional transmission manner through a double-shaft reducer 36 at the power output end of the third micro servo motor 35. Moreover, the inner side of the second nut slider 38 is threadedly connected to the second lead screw 39, so that the third micro servo motor 35 can synchronously drive the two sets of second lead screws 39 to rotate in a counter-direction, thereby enabling the two sets of second nut sliders 38 to move in a counter-directional and mutually separated or approaching displacement on the second lead screw 39. Furthermore, after fixedly connecting the L-shaped arm 32 to the outer side of the second nut slider 38, the relative separation and docking of the two sets of heat conduction plates 4 can be realized by driving the second lead screw 39 to rotate through the third micro servo motor 35.

[0080] Secondly, during the welding process, in order to make the separation gap between the two sets of heat conduction plates 4 parallel to the welding gap, it is necessary to drive the driving gear 19 to rotate through the second micro servo motor 18, and then drive the swing support 3 and the heat conduction plate 4 to rotate relative to the installation plane of the L-shaped support plate 11, so that the separation gap is parallel to the welding gap, so that it will not touch the welding gap during the moving welding process, so as to avoid scratching the welding gap and causing damage to it.

[0081] Refer to the appendix Figure 4 and Figures 12 - 13 , during the welding process, in order to ensure the stability and consistency of the laser beam, it is necessary to cool the lens of the focusing and reflecting module 2 through the water-cooled outer frame 21. At this time, it is necessary to connect the coolant through the water inlet of the water-cooled outer frame 21, and at the same time, after the water-cooled outer frame 21 is heated during circulation, it is discharged from the water outlet of the water-cooled outer frame 21.

[0082] In order to reduce the cooling rate of the weld after welding, liquid inlet ports 41 and liquid outlet ports 42 are respectively arranged at both ends of the heat conduction plate 4, and a fluid channel 47 connecting the liquid inlet port 41 and the liquid outlet port 42 is opened inside it, so as to connect the circulating coolant discharged from the water outlet of the water-cooled outer frame 21 through the liquid inlet port 41, and circulate inside the heat conduction plate 4 through the fluid channel 47, so as to fit and keep warm on both sides of the weld, so that the cooling rate of the welding position is reduced, thereby reducing the generation of residual stress, improving the welding quality, and avoiding cracks or fractures due to too fast cooling after welding.

[0083] Refer to the appendix Figures 9 - 11, in order to blow inert gas (usually argon) to protect the welding position during the welding process, a gas buffer chamber 43 is fixedly installed at one end of the heat conduction plate 4 close to the liquid inlet port 41, and an air inlet port 44 for connecting the blowing protection gas is arranged on the gas buffer chamber 43. At the same time, an air outlet groove 46 perpendicular to the butting surface 45 is opened on the butting surface 45. The air inlet port 44 is connected to a blowing pipeline, and the air outlet groove 46 is connected to the gas buffer chamber 43 through an air duct passing through the heat conduction plate 4 to blow inert gas to the welding position. After passing through the gas buffer chamber 43, the inert gas blows on the welding position through the air outlet groove 46 to protect the welding seam and prevent oxidation or substances such as welding slag and dust from affecting the welding quality.

[0084] In this embodiment, in order to further improve the protection effect on the weld seam, a gas guiding component 5 for changing the air flow direction is installed in the air outlet groove 46. It includes gas guiding pipes 51 symmetrically arranged at both ends of the air outlet groove 46, a V-shaped elastic plate 52 integrally formed between the butting ends of the gas guiding pipes 51, and a positioning shaft 53 fixedly installed in the middle of the air outlet groove 46. A V-shaped groove is formed between the gas guiding pipes 51 and the V-shaped elastic plate 52, and the positioning shaft 53 is embedded in the V-shaped groove. At the same time, an elastic connecting pipe 54 for connecting them to each other is arranged between the butting end faces of the gas guiding pipes 51. When the two heat conduction plates 4 are butted against each other, the exposed surfaces of the two gas guiding components 5 in the opposite combination are also butted against each other at the same time. Thus, under the action of the butting thrust, the V-shaped elastic plate 52 and the elastic connecting pipe 54 are unfolded, and then the gas guiding pipes 51 are stretched to a horizontal state (as shown in the left figure below), and hidden in the air outlet groove 46; during the welding process, the two heat conduction plates 4 are separated from each other. At this time, the butting thrust disappears, and the gas guiding pipes 51 will return to the V-shaped folded state under the action of the rebounding force of the V-shaped elastic plate 52 and the elastic connecting pipe 54 (as shown in the right figure below). Figure 9 When the two heat conduction plates 4 are separated from each other during the welding process, the butting thrust disappears at this time, and the gas guiding pipes 51 will return to the V-shaped folded state under the action of the rebounding force of the V-shaped elastic plate 52 and the elastic connecting pipe 54 (as shown in the right figure below). Figure 9 As shown in the right figure.

[0085] Furthermore, by connecting the two gas guiding components 5 arranged oppositely to the matching gas buffer chamber 43, and setting the air flow directions between them to be reversed (that is, one group of gas guiding pipes 51 inputs inert gas from the end close to the gas buffer chamber 43, and the other group of gas guiding pipes 51 inputs inert gas from the end far from the gas buffer chamber 43. The two are connected to the gas buffer chamber 43 through an elastic hose passing through the heat conduction plate 4, which is not shown in the figure). In this way, when the two gas guiding components 5 return to the V-shaped folded state, a diamond-shaped frame can be relatively formed to enclose the welding position, and a spiral air flow is formed by using the alternately flowing air flows (as shown in the figure below). Figure 11The welding position is fully surrounded by protection (shown by the dotted line in the figure) to form a swirling protective layer, isolating the welding position from the outside world. While preventing oxidation, cleaning slag and dust at the welding position, it does not form a situation of direct air blowing, which can slow down the temperature drop at the welding position, reduce the generation of residual stress, and ensure the stability of the welding structure. When deformation occurs, a swirling airflow that connects head to tail is formed to protect the welding position.

[0086] Of course, in other embodiments, the air guiding assembly 5 may not be provided, and the inert gas can be directly output through the air outlet groove 46 to protect the welding position. During actual production, the choice is made according to production requirements.

[0087] The working principle of this embodiment is as follows: First, the position of the welding module 200 is adjusted by the robot body 100 to adapt it to the position of the workpiece to be welded, and the opposing heat conduction plates 4 are attached to the surface of the welding position of the workpiece to be welded. Then, the preheating laser is emitted through the laser 24, the coupling and reflecting mirror barrel 22, and the focusing and reflecting module 2, and is irradiated on the opposing heat conduction plates 4. Under the action of the welding laser, it gradually heats up, and at the same time, the workpiece to be welded in contact with it is preheated to reduce the prestress.

[0088] Secondly, when the preheating temperature of the workpiece reaches the preset range, the second lead screw 39 is rotated by the third micro servo motor 35 to realize the relative separation of the two heat conduction plates 4, so that the laser can pass through the gap between them to weld the workpiece. At the same time, the second micro servo motor 18 is used to drive the driving gear 19 to rotate, driving the heat conduction plate 4 to rotate, making the separation gap parallel to the weld seam, so as not to cause interference during the moving welding. At the same time, the inlet port 41 is connected to the circulating coolant discharged from the water outlet of the water-cooled outer casing 21, and circulates through the fluid channel 47 inside the heat conduction plate 4 to keep warm on both sides of the weld seam during docking, reducing the cooling rate of the welding position, and thus reducing the generation of residual stress.

[0089] Furthermore, during the welding process, the air inlet port 44 can be connected to a blowing pipeline, and the inert gas passes through the air buffer chamber 43 and circulates and blows the air flow from the diamond-shaped frame formed in the V-shaped folded state, so as to form a swirling airflow by using the alternately flowing airflows to fully surround and protect the welding position, forming a swirling protective layer, isolating the welding position from the outside world. While preventing oxidation, cleaning slag and dust at the welding position, it does not form a situation of direct air blowing, which can slow down the temperature drop at the welding position, reduce the generation of residual stress.

[0090] As Figures 1 - 14 shown, a welding residual stress monitoring system for a welding robot is applied to the welding robot in the above embodiment, and includes:

[0091] The stress and temperature acquisition module monitors the initial temperature, preheating temperature, welding temperature, and residual temperature at the welding position in real time through the thermal imaging temperature monitor 23, and conducts a comparative analysis by using the collected temperature values and the preset welding stress range.

[0092] Preset the correspondence between the initial temperature range of the workpiece, the temperature difference range during the welding process, the residual temperature range after welding, and the welding stress state in the control system. Then, the stress state of the workpiece during welding can be judged according to the obtained real-time temperature values, and it can be classified into a low stress state, a moderate stress state, and a high stress state.

[0093] The welding preheating module emits preheating laser through the laser 24, the coupling and reflecting mirror barrel 22, and the focusing and reflecting module 2, irradiates the preheating laser on the heat conduction plate 4 to preheat the workpiece to be welded in contact with it, and at the same time adjusts the welding laser power to reach the required welding power. The thermal imaging temperature monitor 23 is used to monitor the preheating temperature of the workpiece to be welded until the required temperature range is reached (that is, the workpiece reaches the low stress state or the moderate stress state at this time).

[0094] The welding stress monitoring module obtains the actual temperature at the welding position of the workpiece during the welding process and the temperature value of the welding laser through the thermal imaging temperature monitor 23, conducts a comparative analysis on the two groups of collected temperature values, conducts a comparative analysis with the preset welding temperature rise range, obtains the temperature rise state of the workpiece (that is, the temperature difference range during the welding process), and conducts a comparative analysis according to the temperature rise state and the preset welding stress range to obtain the welding stress state (that is, judge whether the weld is in a low stress state, a moderate stress state, or a high stress state at this time). Then, the welding quality and structural strength of the weld are evaluated accordingly, which brings convenience to the subsequent quality inspection.

[0095] The welding slow cooling module connects the heated circulating coolant of the water-cooled outer casing 21 through the liquid inlet port 41, insulates the welding position through the fluid channel 47 to achieve the purpose of slow cooling. At the same time, the thermal imaging temperature monitor 23 is used to monitor the temperature value during the slow cooling of the welded workpiece, and a comparative analysis is conducted according to the temperature value and the preset welding stress range to obtain the residual stress state (that is, judge whether the weld is in a low stress state, a moderate stress state, or a high stress state at this time).

[0096] Finally, the welding quality and structural strength of the overall weld can be comprehensively evaluated by combining the residual stress state and the welding stress state, so as to conduct targeted quality inspection on the welds with poor stress state, determine whether they meet the production requirements, whether welding repair is needed, etc., and provide a reference for the quality inspection work to improve the quality inspection efficiency.

[0097] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. The structures, devices, and operation methods not specifically described and explained in the present invention are implemented by conventional means in the art without special instructions and limitations.

Claims

1. A welding robot, comprising a robot body (100), characterized in that: A welding module (200) installed at the free end of the robot body (100); Wherein, the welding module (200) comprises: A fixed support (1) fixedly connected to the free end of the robot body (100), an L-shaped support plate (11) being vertically mounted on the fixed support (1); A focusing reflection module (2) fixedly mounted on the fixed support (1), wherein a water-cooling outer frame (21) for cooling a lens is provided at the bottom of the focusing reflection module (2), a coupling reflection lens barrel (22) is mounted on one side of the focusing reflection module (2), and a laser (24) for emitting laser light and a thermal imaging temperature monitor (23) for detecting the temperature of a welding workpiece are mounted on the coupling reflection lens barrel (22); A swivel support (3) rotatably mounted on the bottom of the L-shaped support plate (11), wherein L-shaped support arms (32) are slidably mounted on opposite sides of the swivel support (3); A heat conduction plate (4) is fixedly mounted on the bottom of the L-shaped support arm (32), wherein a butt cut surface (45) is provided on one opposite side of the heat conduction plate (4), and the butt cut surface (45) is used to block the welding workpiece and the pre-adjusted laser beam to preheat the welding workpiece, and a liquid inlet port (41) and a liquid outlet port (42) are provided at both ends of the heat conduction plate (4), and a fluid channel (47) connecting the liquid inlet port (41) and the liquid outlet port (42) is provided inside the heat conduction plate (4), so that the circulating coolant connected to the water-cooled outer frame (21) through the liquid inlet port (41) passes through the fluid channel (47) to slowly cool the welding position; A gas buffer chamber (43) is fixedly mounted on one end of the heat conducting plate (4) close to the liquid inlet port (41); the gas buffer chamber (43) is provided with a gas inlet port (44) for connecting to blow a protective gas; a gas outlet groove (46) perpendicular to the butt joint surface (45) is provided; the gas outlet groove (46) is connected to the gas buffer chamber (43) to blow the protective gas to the welding position; An air guide assembly (5) for changing the direction of air flow is installed in the air outlet groove (46), comprising an air guide tube (51) symmetrically arranged at both ends of the air outlet groove (46), a V-shaped elastic plate (52) integrally formed between the butt ends of the air guide tube (51), and a positioning shaft (53) fixedly installed in the middle of the air outlet groove (46), a V-shaped groove is formed between the air guide tube (51) and the V-shaped elastic plate (52), and the positioning shaft (53) is embedded in the V-shaped groove, and an elastic connecting tube (54) for connecting the butt end surfaces of the air guide tube (51) is arranged between them.

2. A welding robot according to claim 1, characterized in that: A lifting mechanism for driving the L-shaped support plate (11) to vertically lift is provided between the fixed support (1) and the L-shaped support plate (11), comprising a first micro servo motor (12) fixedly mounted on the top surface of the fixed support (1), a first lead screw (13) rotatably mounted on the fixed support (1), and a first nut slide (14) threadedly connected to the first lead screw (13); a power output end of the first micro servo motor (12) is transmission-connected to the first lead screw (13) via a reducer; a limit support rod (15) is fixedly mounted on the fixed support (1) in parallel and symmetrically with the first lead screw (13); a limit slide (16) is slidably mounted on the limit support rod (15); and the L-shaped support plate (11) is fixedly mounted on the first nut slide (14) and the limit slide (16).

3. A welding robot according to claim 1, characterized in that: The L-shaped support plate (11) is provided with a mounting through hole (17) which coincides with the central axis of the lens of the focusing reflective module (2); a connecting seat (31) is integrally formed on the top surface of the rotary pendulum support (3) and is rotatably mounted in the mounting through hole (17); a ring-shaped light source (33) for fill light is fixedly mounted at the center of the connecting seat (31); and a rotating mechanism is provided between the connecting seat (31) and the L-shaped support plate (11) for driving the rotary pendulum support (3) to rotate in a circumferential direction relative to the L-shaped support plate (11).

4. A welding robot according to claim 3, characterized in that: The turnover mechanism comprises a second micro servo motor (18) fixedly mounted on the L-shaped support plate (11), a driving gear (19) drivingly connected to a power output end of the second micro servo motor (18) via a reducer, and a driven gear (34) fixedly sleeved on an outer surface of the connecting seat (31), the driving gear (19) meshing with the driven gear (34).

5. A welding robot according to claim 1, characterized in that: A third micro servo motor (35) is fixedly mounted at the center of the side of the swing support (3); the swing support (3) is symmetrically provided with slide grooves (37) on both sides of the third micro servo motor (35); a second nut slide (38) is slidably mounted inside the slide groove (37); a power output end of the third micro servo motor (35) is connected to a second lead screw (39) in opposite directions through a dual-axis reducer (36); the inner side of the second nut slide (38) is threadedly connected to the second lead screw (39), and the outer side is fixedly connected to the L-shaped support arm (32).

6. A welding robot according to claim 1, characterized in that: The butt-jointed cut surface (45) is a vertical butt-jointed surface or an inclined butt-jointed surface, and the inclination angle is 15°-60°.

7. A welding robot according to claim 1, characterized in that: The two groups of air guide components (5) arranged opposite to each other are both connected to the matching air buffer chamber (43), and the airflow directions between the two are reversed so as to form a spiral airflow connected end to end to protect the welding position when deformation occurs.

8. A welding residual stress monitoring system for a welding robot, applied to the welding robot according to any one of claims 1 to 7, characterized in that: include: A stress temperature acquisition module, which uses a thermal imaging temperature monitor (23) to monitor the initial temperature, preheating temperature, welding temperature and residual temperature at the welding position in real time, and compares and analyzes the collected temperature values ​​with a preset welding stress range; A welding preheating module, which emits a preheating laser through a laser (24), a coupled reflective lens barrel (22) and a focusing reflective module (2), and irradiates the preheating laser onto a heat conducting plate (4) to preheat a workpiece to be welded that is in contact with the heat conducting plate (4), and at the same time adjusts the welding laser power to reach the power required for welding, and uses a thermal imaging temperature monitor (23) to monitor the preheating temperature of the workpiece to be welded until the required temperature range is reached; The welding stress monitoring module acquires the actual temperature of the welding position of the workpiece and the temperature value of the welding laser during the welding process through a thermal imaging temperature monitor (23), compares and analyzes the two sets of temperature values ​​acquired, and compares and analyzes them with the preset welding temperature rise range to obtain the temperature rise state of the workpiece, and compares and analyzes the temperature rise state with the preset welding stress range to obtain the welding stress state; The welding slow cooling module is connected to the heated circulating coolant of the water-cooled outer frame (21) through the liquid inlet port (41), and the welding position is kept warm through the fluid channel (47) to achieve the purpose of slow cooling. At the same time, a thermal imaging temperature monitor (23) is used to monitor the temperature value of the welding workpiece during slow cooling, and a comparison analysis is performed based on the temperature value and the preset welding stress range to obtain the residual stress state.

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