A welding robot and a control method thereof
By designing a highly adaptable welding robot, the problems of welding quality and consistency of large-size thick plate workpieces have been solved, achieving efficient and low-cost welding results, and making it suitable for a wide range of welding needs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHENGDU UNIV OF INFORMATION TECH
- Filing Date
- 2026-03-11
- Publication Date
- 2026-06-23
Smart Images
Figure CN121820969B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of welding robot technology, and more specifically to a welding robot and its control method. Background Technology
[0002] With the widespread application of large metal structural components in shipbuilding, engineering machinery, steel structures and pressure vessels, the size of workpieces is constantly increasing. Especially in the welding connection of flat workpieces, there are a large number of long straight lines or gradually changing curves in the welding joints. Moreover, these welding joints usually have large joint depths and bevel angles, which puts forward higher requirements for welding quality and consistency.
[0003] Currently, manual welding is commonly used for welding thick plate workpieces like this. This relies on the welder's extensive experience to control the welding torch's posture and oscillation trajectory (using techniques such as "floating," "folding," and "shaking") to regulate the molten pool and ensure weld quality. However, manual welding suffers from high labor intensity, dependence on welder experience for quality, and poor consistency in weld quality across different workpieces, making it difficult to meet the demands of large-scale production.
[0004] To improve the level of welding automation, various welding robots or automated welding equipment have been proposed in the existing technology. Among them, multi-joint welding robots (such as the mobile intelligent welding robot and welding method disclosed in Chinese patent document CN202310496433.X) realize the motion control of the welding torch in space through a multi-degree-of-freedom robotic arm, which can accurately reach the welding joint position and realize the welding operation along the preset path. However, its structure is complex and costly, and it is heavily dependent on the control system and trajectory planning. In large-sized workpieces or factory operation environments, it is easily limited by the working radius, unusual configuration, and installation position, and it is difficult to realize the welding techniques used in manual welding, making it difficult to guarantee the quality of the weld.
[0005] In addition, although track-type or gantry-type welding equipment can cover a large welding area, the movement of its welding torch is mostly linear or simple oscillation. The welding process usually uses fixed parameters, which makes it difficult to adapt to the welding requirements of the changing width of the filler layer during the layer-by-layer filling process in thick plate welding. This leads to problems such as incomplete fusion, uneven filling, or poor weld formation in the filler welding of thick workpieces.
[0006] Therefore, there is an urgent need for a welding robot with a simplified structure and a large coverage area, which can be used to weld and fill joints with large depths and bevel angles layer by layer, and can adjust the width of the molten pool accordingly to form high-quality welds. Summary of the Invention
[0007] The purpose of this invention is to provide a welding robot and its control method for use in thick plate welding scenarios, replacing manual labor in highly repetitive welding operations, facilitating batch welding production of workpieces. Its structure is simple, the welding actions are easy to perform, and during the welding process, it can perform layer-by-layer welding filling based on a welding strategy formulated according to the characteristics of the joint to be welded, and correspondingly change the width of the molten pool coverage to form a high-quality weld.
[0008] The first aspect of the present invention provides a welding robot, which includes a moving component and a welding component; the moving component includes a slide rail, a strut, and a telescopic frame; the slide rail is fixedly arranged along a first direction; the strut is arranged along a second direction and slidably connected to the slide rail, the two sliding relative to each other in a direction parallel to the first direction; the telescopic frame is vertically arranged and its fixed end is slidably connected to the strut, the two sliding relative to each other in a direction parallel to the second direction; the welding component includes a frame, a crank, a rotating rod, a connecting rod, and a welding torch; the frame is rotatably mounted on the free end of the telescopic frame; one end of the crank is hinged to a first hinge shaft on the frame, and a second hinge shaft is provided on the other end of the crank. A rotating shaft; one end of the rotating rod is hinged to a second hinge shaft on the frame, and a second rotating shaft is provided on the other end of the rotating rod; one end of the connecting rod is hinged to the first rotating shaft, and the other end is hinged to the second rotating shaft; the welding torch is installed in the middle of the connecting rod; the distance from the first hinge shaft to the first rotating shaft is equal to the distance from the second hinge shaft to the second rotating shaft, and the crank and the rotating rod rotate in opposite directions, so that when the crank rotates continuously, the tungsten electrode tip of the welding torch moves in a figure-eight trajectory; the axis of rotation of the frame relative to the free end is defined as the baseline, the baseline is vertical, and the intersection of the figure-eight trajectory when the welding torch is located at the midpoint of the connecting rod is located on the baseline.
[0009] Therefore, by moving the component, the welding component can be controlled to move freely along the first direction, the second direction, and the height direction, and the movement in the three directions can be controlled independently, simplifying the control process and facilitating automation. Through the constraint of the four-bar linkage consisting of the frame, crank, rotating rod, and connecting rod, the welding torch can be made to swing in a figure-eight trajectory. Combined with the movement of the welding torch along the length of the joint, it can simulate the welding technique of a welder, forming a weld that covers the width of the joint, resulting in high-quality weld connection.
[0010] However, for thick plate welded joints with deep joints, beveling is usually required, resulting in a cross-sectional shape that is narrow at the bottom and wide at the top. The single oscillation amplitude of the welding torch is difficult to adapt to the joint width at different welding depths.
[0011] Furthermore, the first rotating shaft is slidably connected to the crank, and the direction in which they slide relative to each other is parallel to the length direction of the crank. A first telescopic unit is installed on the crank, and the first telescopic unit is used to push the first rotating shaft to slide. The second rotating shaft is slidably connected to the rotating rod, and the direction in which they slide relative to each other is parallel to the length direction of the rotating rod. A second telescopic unit is installed on the rotating rod, and the second telescopic unit is used to push the second rotating shaft to slide.
[0012] Therefore, by sliding the first shaft along the length of the crank and the second shaft along the length of the connecting rod, the crank constraint length and the connecting rod constraint length (i.e., the effective length that actually acts as a constraint in the four-bar linkage) in the four-bar linkage can be changed. This, in turn, can change the length of the figure-eight trajectory of the welding torch. Thus, the figure-eight trajectory of the welding torch can be adapted to joints of different widths, preventing the weld from being too wide or too narrow during welding operations.
[0013] However, for welded joints that are curved or bent (with corners), the amount of molten metal required on the outside and inside of the joint is obviously different in the corner section. Therefore, the above-mentioned welding robot used to weld corner sections will obviously result in incomplete welding on the outside and / or overflow on the inside.
[0014] Furthermore, the welding torch is slidably connected to the connecting rod, and the direction of their relative sliding is parallel to the length direction of the connecting rod. A third telescopic unit is installed on the connecting rod, and the third telescopic unit is used to push the welding torch to slide. The distance between the axis of the welding torch and the midpoint of the connecting rod is less than half the distance from the first hinge axis to the first rotating axis.
[0015] Furthermore, the welding torch is tilted, and the axis of the welding torch forms an angle of 10° to 20° with the baseline.
[0016] Furthermore, a counterweight is installed on the rotating rod, and the center of gravity of the counterweight is eccentric to the second hinge axis.
[0017] Furthermore, a first motor is fixedly mounted on the slide rail, and a first screw is rotatably mounted on the slide rail. The crossbar is threadedly connected to the first screw, and the first motor drives the first screw to rotate. A second motor is fixedly mounted on the crossbar, and a second screw is rotatably mounted on the crossbar. The fixed end is threadedly connected to the second screw, and the second motor drives the second screw to rotate. A third motor is fixedly mounted on the fixed end, and a third screw is rotatably mounted on the fixed end. The free end is threadedly connected to the third screw, and the third motor drives the third screw to rotate.
[0018] Furthermore, a first drive motor is fixedly installed on the free end, and the first drive motor is used to drive the frame to rotate; the first drive motor is a servo motor or a stepper motor.
[0019] A second aspect of the present invention provides a control method for controlling a welding robot to weld two workpieces to be joined. The control method includes: S1, acquiring joint information of the two workpieces to be joined, the joint information including a joint trajectory; S2, controlling the moving component to move the welding component, such that the tungsten electrode tip is located at a preset depth position of the joint, and the vertical projection of the baseline is located on the joint trajectory; S3, controlling the moving component to move the welding component, such that the vertical projection of the baseline moves along the joint trajectory and controlling the welding torch to perform welding.
[0020] Furthermore, controlling the moving component to drive the welding component to move includes: controlling the span frame to slide along a first direction and controlling the telescopic frame to slide along a second direction, so that the free end translates in the horizontal direction; controlling the telescopic frame to extend and retract in the vertical direction so that the free end translates in the vertical direction.
[0021] Furthermore, S3 includes: when welding the bottom of the joint, locking the crank while controlling the welding torch to perform welding; when welding the upper part of the joint, controlling the crank to rotate continuously while controlling the welding torch to perform welding, so that the welding torch moves along the length direction of the joint and swings along the width direction of the joint.
[0022] Furthermore, the joint information also includes joint depth, bevel angle, and root gap; when welding the upper part of the joint, based on the joint depth, the bevel angle, the root gap, and the depth of the welding position, the first rotating shaft is controlled to slide along the length direction of the crank and the second rotating shaft is controlled to slide along the length direction of the rotating rod, so that the amplitude of the welding torch swinging along the joint width direction is adapted to the joint width of the welding position.
[0023] Furthermore, for the V-shaped bevel, after controlling the first rotating shaft to slide along the length direction of the crank, the distance from the first hinge shaft to the first rotating shaft, and after controlling the second rotating shaft to slide along the length direction of the rotating rod, the distance from the second hinge shaft to the second rotating shaft, are obtained as follows:
[0024] ,in, L 1 This indicates the distance from the first hinge shaft to the first rotating shaft after the first rotating shaft is controlled to slide along the length direction of the crank. L2 This indicates the distance from the second hinge shaft to the second rotating shaft after the second rotating shaft has slid along the length of the rotating rod. H Indicates the seam depth. h Indicates the depth of the weld position. θ Indicates the bevel angle. d This indicates the root gap.
[0025] Further, S3 includes: S31, pre-connection, determining multiple pre-connection points along the joint length direction, controlling the moving component to drive the welding component to move to each of the pre-connection points and perform spot welding; the spot welding sequence is: alternating from the middle to both ends of the joint length direction, one pre-connection point at a time; S32, segmented welding, identifying the segment between any two adjacent pre-connection points as the segment to be welded, controlling the moving component to drive the welding component to alternately weld the segments to be welded from the middle to both ends of the joint length direction.
[0026] Furthermore, when welding the upper part of the joint, for the corner section of the joint, when controlling the welding gun to perform welding, the frame is controlled to rotate around the baseline so that the plane where the first hinge axis and the second hinge axis are located coincides with the normal of the joint trajectory of the corner section.
[0027] Furthermore, when welding the upper part of the joint, for the corner section of the joint, when controlling the welding gun to perform welding, the welding gun is controlled to slide a preset distance outward along the length direction of the connecting rod towards the corner, and the projection of the baseline in the vertical direction is controlled to slide a preset distance inward along the normal of the joint trajectory of the corner section towards the corner.
[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0029] 1. The welding robot and its control method provided in this disclosure, by driving the crank to rotate continuously while the welding assembly moves along the joint trajectory, can force the welding torch installed in the middle of the connecting rod to move continuously along an 8-shaped trajectory under the constraint of the four-bar linkage consisting of the frame, crank, rotating rod, and connecting rod; and by adjusting the frame to rotate around the baseline until the plane of the first hinge axis and the second hinge axis is perpendicular to the joint, the 8-shaped trajectory can "cross" the joint. Then, while the welding torch moves along the length of the joint, the welding torch also swings along the normal of the joint, so that the weld pool spreads out in the width direction of the joint, which is beneficial to increase the coverage width of the weld, strengthen the fusion connection between the weld and the bevel surface, and improve the weld connection quality and appearance quality.
[0030] 2. The welding robot and its control method provided in this embodiment of the present disclosure, by slidingly connecting the first rotating shaft to the crank and the second rotating shaft to the rotating rod, enables the crank constraint length and the rotating rod constraint length in the four-bar linkage to be adjustable; thus, the welding robot provided in this embodiment can change the length of the figure-eight trajectory by changing the crank constraint and rotating rod constraint length in the four-bar linkage, thereby changing the width of the weld pool in the width direction of the joint when the welding torch is still swinging along the normal of the joint, so that the width of the weld pool in the width direction of the joint matches the width of the joint when the welding torch is swinging along the normal of the joint, thereby avoiding incomplete welding or overflow in the width direction of the joint;
[0031] 3. The welding robot and its control method provided in this disclosure, by sliding the welding torch to the connecting rod, allows the distance between the welding torch and the first and second rotating shafts to be adjustable; thereby, by changing the distance between the welding torch and the first and second rotating shafts, the shape of the figure-eight trajectory can be changed so that one end is larger and the other end is smaller. Thus, when facing a curved joint trajectory, at the corner section of the joint, by sliding the welding torch along the length of the connecting rod, the larger end of the figure-eight trajectory is located outside the corner and the smaller end is located inside the corner, thereby ensuring that both the inside and outside of the corner section are well filled by the molten pool. Attached Figure Description
[0032] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:
[0033] Figure 1 A three-dimensional structural schematic diagram of a welding robot according to an embodiment of the present invention;
[0034] Figure 2 According to Figure 1 A magnified view of a portion of area A;
[0035] Figure 3 A three-dimensional structural schematic diagram of a welding assembly according to an embodiment of the present invention;
[0036] Figure 4 One of the simplified kinematic diagrams of the welding assembly drawn according to an embodiment of the present invention;
[0037] Figure 5 A second simplified diagram of the mechanism motion of the welding assembly according to an embodiment of the present invention;
[0038] Figure 6 The third simplified diagram of the mechanism motion of the welding assembly according to an embodiment of the present invention;
[0039] Figure 7A comparative schematic diagram of the motion of the mechanism for changing the crank length of the welding assembly according to an embodiment of the present invention;
[0040] Figure 8 This is a comparative schematic diagram of the mechanism for changing the position of the welding torch in the welding assembly, drawn according to an embodiment of the present invention.
[0041] The attached diagram shows the markings and corresponding component names:
[0042] 11-Slide rail; 111-First motor; 112-First screw; 12-Frame; 121-Second motor; 122-Second screw; 13-Telescopic frame; 131-Fixed end; 132-Free end; 133-Third motor; 134-Third screw; 135-First drive motor; 21-Frame; 211-First hinge shaft; 212-Second hinge shaft; 213-Second drive motor; 22-Crank; 221-First rotating shaft; 222-First telescopic unit; 23-Rotating rod; 231-Second rotating shaft; 232-Second telescopic unit; 24-Connecting rod; 241-Third telescopic unit; 25-Welding torch. Detailed Implementation
[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for illustrative purposes only and are not intended to limit the invention. It should be noted that this invention is already in the actual research and development stage.
[0044] Welding is a crucial method for fixing mechanical components. To improve processing efficiency, welding robots have been widely introduced into production to replace simple and repetitive tasks. However, for deep weld seams, welding robots struggle to replicate the welder's technique to fill the seam. Even when welding robots perform multiple welds along the joint's length to achieve the required width, the weld quality remains relatively low (primarily due to insufficient bonding between welds). Therefore, such weld seams still primarily rely on manual welding by welders.
[0045] To address this, the present invention provides a welding robot and its control method for replacing welders in highly repetitive welding operations in thick plate welding scenarios, facilitating the mass production of such workpieces. When welding wide weld seams, it can mimic the welding techniques of welders to laterally push the molten pool (meaning pushing the molten pool along the normal direction of the joint at the welding position), so that the molten pool covers the entire joint during single-layer welding, forming an integrated weld layer, thereby making the weld quality approach that of manual welding by welders.
[0046] Example 1:
[0047] like Figures 1 to 3 As shown, this embodiment provides a welding robot, which includes a moving component and a welding component;
[0048] The moving component includes a slide rail 11, a strut 12, and a telescopic frame 13;
[0049] The slide rail 11 is fixedly arranged along a first direction; the cross frame 12 is arranged along a second direction and slidably connected to the slide rail 11, and the relative sliding direction of the two is parallel to the first direction; the telescopic frame 13 is vertically arranged and its fixed end 131 is slidably connected to the cross frame 12, and the relative sliding direction of the two is parallel to the second direction;
[0050] The welding assembly includes a frame 21, a crank 22, a rotating rod 23, a connecting rod 24, and a welding torch 25;
[0051] The frame 21 is rotatably mounted on the free end 132 of the telescopic frame 13; one end of the crank 22 is hinged to the first hinge shaft 211 on the frame 21, and a first rotating shaft 221 is provided on the other end of the crank 22; one end of the rotating rod 23 is hinged to the second hinge shaft 212 on the frame 21, and a second rotating shaft 231 is provided on the other end of the rotating rod 23; one end of the connecting rod 24 is hinged to the first rotating shaft 221, and the other end is hinged to the second rotating shaft 231; the welding torch 25 is mounted in the middle of the connecting rod 24;
[0052] The distance from the first hinge shaft 211 to the first rotating shaft 221 is equal to the distance from the second hinge shaft 212 to the second rotating shaft 231, and the crank 22 and the rotating rod 23 rotate in opposite directions, so that when the crank 22 rotates continuously, the tungsten electrode tip of the welding torch 25 moves in a figure-eight trajectory.
[0053] The axis of rotation of the frame 21 relative to the free end 132 is defined as the baseline. The intersection of the figure-eight trajectory when the welding torch 25 is located at the midpoint of the connecting rod 24 is located on the baseline.
[0054] Accordingly, after the welding assembly is moved to the designated position by the moving component, the welding assembly is moved along the joint trajectory of the two workpieces to be welded by the moving component, and the welding operation can be performed on the joint; in particular, while the welding assembly moves along the joint trajectory, the crank 22 is driven to rotate continuously (in this embodiment, a second drive motor 213 is installed on the frame 21, and the second drive motor 213 drives the crank 22 to rotate continuously), so that under the constraint of the four-bar linkage composed of the frame 21, crank 22, rotating rod 23, and connecting rod 24, the welding torch 25 installed in the middle of the connecting rod 24 is forced to move continuously in a figure-eight trajectory (refer to...). Figure 4 , Figure 5Obviously, at this time, by adjusting the frame 21 to rotate around the baseline until the plane containing the first hinge axis 211 and the second hinge axis 212 is perpendicular to the joint, the figure-eight trajectory can be made to "cross" the joint. Accordingly, while the welding torch 25 moves along the length of the joint, the welding torch 25 also swings along the normal of the joint, which can make the weld pool spread out in the width direction of the joint, which is beneficial to increase the coverage width of the weld, strengthen the fusion connection between the weld and the bevel surface, and improve the weld connection quality and appearance quality. It is especially suitable for welding connections of wide joints.
[0055] Obviously, the welding robot provided in this embodiment is particularly suitable for continuous welding operations, and correspondingly, it is particularly suitable for welding operations based on argon arc welding.
[0056] Specifically, such as Figure 1 As shown, a first motor 111 is fixedly installed on the slide rail 11, and a first screw 112 is rotatably installed on the slide rail 11. The cross frame 12 is threadedly connected to the first screw 112, and the first motor 111 is used to drive the first screw 112 to rotate.
[0057] A second motor 121 is fixedly installed on the span frame 12, and a second screw 122 is rotatably installed on the span frame 12. The fixed end 131 is threadedly connected to the second screw 122, and the second motor 121 is used to drive the second screw 122 to rotate.
[0058] A third motor 133 is fixedly installed on the fixed end 131, and a third screw 134 is rotatably installed on the fixed end 131. The free end 132 is threadedly connected to the third screw 134, and the third motor 133 is used to drive the third screw 134 to rotate.
[0059] Accordingly, the welding robot provided in this embodiment utilizes screw transmission, enabling the first motor 111 to achieve the sliding motion of the span 12 along a first direction, the second motor 121 to achieve the sliding motion of the telescopic frame 13 along a second direction, and the third motor 133 to achieve the telescopic movement of the telescopic frame 13. It can reliably position and suppress vibration based on the self-locking characteristics of the threaded connection, and ensures high precision in the sliding motion of the span 12 and the telescopic frame 13, as well as the telescopic movement of the telescopic frame 13. For the welding scenario of this application, the high-precision telescopic movement and reliable self-locking positioning of the telescopic frame 13 enable the welding assembly to reliably reach and maintain a preset height position; the high-precision sliding of the span 12 and the telescopic frame 13 ensures that the welding assembly moves along a preset trajectory.
[0060] Preferably, such as Figure 3 As shown, the welding torch 25 is inclined, and the axis of the welding torch 25 forms an angle of 10° to 20° with the baseline.
[0061] Accordingly, the tilted welding torch 25 can reduce molten pool overflow or spatter; help push the molten pool metal to the weld edge and enhance weld toe filling; and effectively guide the shielding gas to the molten pool surface, etc.
[0062] Preferably, a counterweight is fixedly installed on the rotating rod 23, and the center of gravity of the counterweight is eccentric to the second hinge shaft 212.
[0063] Therefore, during the continuous rotation of crank 22, by setting a counterweight (not shown in the figure), the moment of inertia of the rotating rod 23 can be increased, thereby ensuring that it smoothly passes through the dead point position (i.e., the position where crank 22 and rotating rod 23 are collinear), and after passing through the dead point, it still maintains rotation in the opposite direction to that of crank 22. It should be understood that when controlling crank 22 to stop, it should be avoided to stop when rotating rod 23 is at the dead point position. If it stops at the dead point position, it should be manually adjusted until rotating rod 23 passes through the dead point before crank 22 is restarted to continue rotating.
[0064] Preferably, such as Figure 2 , Figure 3 As shown, a first drive motor 135 is fixedly installed on the free end 132. The first drive motor 135 is used to drive the frame 21 to rotate. The first drive motor 135 is a servo motor or a stepper motor.
[0065] Accordingly, the first drive motor 135 can reliably determine the angle of rotation of the drive frame 21 relative to the free end 132. When the crank 22 is not rotating, it can ensure that the direction in which the welding torch 25 blows the molten pool coincides with the forward direction of the welding torch 25. When the crank 22 is rotating, it can ensure that the length direction of the figure-eight trajectory of the welding torch 25 when it swings at any position along the joint length (i.e., the length direction of the figure-eight trajectory) is... Figure 4 The direction of the line connecting the first hinge axis 211 and the second hinge axis 212 coincides with the normal direction of the joint at that position.
[0066] Example 2:
[0067] like Figure 2 , Figure 3 As shown, this embodiment is based on embodiment 1, the difference being that in this embodiment:
[0068] The first rotating shaft 221 is slidably connected to the crank 22 and the direction in which they slide relative to each other is parallel to the length direction of the crank 22. A first telescopic unit 222 is installed on the crank 22 and the first telescopic unit 222 is used to push the first rotating shaft 221 to slide.
[0069] The second rotating shaft 231 is slidably connected to the rotating rod 23 and the direction of their relative sliding is parallel to the length direction of the rotating rod 23. A second telescopic unit 232 is installed on the rotating rod 23, and the second telescopic unit 232 is used to push the second rotating shaft 231 to slide.
[0070] It should be understood that the first telescopic unit 222 and the second telescopic unit 232 can be mature products from the existing technology. For example, in this embodiment, a screw drive is used. Taking the crank 22 as an example, an adjusting screw is rotatably installed on the crank 22, and a thread is made on the first rotating shaft 221 so that the first rotating shaft 221 and the adjusting screw are threadedly connected. Then, by rotating the adjusting screw, the first rotating shaft 221 can be pushed to slide along the length direction of the crank 22. Obviously, linear motors and other electrical control devices can also be used, which will not be elaborated here.
[0071] Accordingly, the welding robot provided in this embodiment, by slidingly connecting the first rotating shaft 221 to the crank 22 and the second rotating shaft 231 to the rotating rod 23, enables the adjustment of the constraint length of the crank 22 (i.e., the distance from the first rotating shaft 221 to the first hinge shaft 211) and the constraint length of the rotating rod 23 (i.e., the distance from the second rotating shaft 231 to the second hinge shaft 212) in the four-bar linkage; furthermore, the welding robot provided in this embodiment can change the length of the figure-eight trajectory (i.e., the distance of the figure-eight trajectory in the four-bar linkage) by changing the constraint lengths of the crank 22 and the rotating rod 23 in the four-bar linkage. Figure 4 The dimensions of the line connecting the first hinge axis 211 and the second hinge axis 212 can correspondingly change the width of the figure-eight trajectory covering the joint. Accordingly, when the welding torch 25 oscillates along the normal to the joint, the width of the weld pool spreading in the width direction of the joint can be changed. Obviously, the width is smaller for the lower part of the joint and larger for the upper part. In this embodiment, by changing the length of the figure-eight trajectory, the width of the weld pool spreading in the width direction of the joint can be adapted to the width of the joint when the welding torch 25 oscillates along the normal to the joint, thereby avoiding incomplete welding or overflow in the width direction of the joint.
[0072] In response, Figure 7 A comparative schematic diagram of the motion of the welding assembly mechanism when the length of crank 22 changes is drawn, where figure a (corresponding to) Figure 5 ) and map b (corresponding to Figure 4The difference between the links in the diagram is that the length of crank 22 in diagram a is greater than the length of crank 22 in diagram b, and the length of rotating rod 23 in diagram a is greater than the length of rotating rod 23 in diagram b (that is, corresponding to the aforementioned sliding of the first rotating shaft 221 and the corresponding sliding of the second rotating shaft 231, which increases the constraint length of crank 22 and the constraint length of rotating rod 23). Correspondingly, the length of the figure-eight trajectory formed by the movement of the midpoint of connecting rod 24 in diagram a is greater than the length of the figure-eight trajectory formed by the movement of the midpoint of connecting rod 24 in diagram b.
[0073] Example 3:
[0074] like Figure 2 , Figure 3 As shown, this embodiment is based on embodiment 1, the difference being that in this embodiment:
[0075] The welding torch 25 is slidably connected to the connecting rod 24 and the direction of their relative sliding is parallel to the length direction of the connecting rod 24. A third telescopic unit 241 is installed on the connecting rod 24 and the third telescopic unit 241 is used to push the welding torch 25 to slide.
[0076] The distance between the axis of the welding torch 25 and the midpoint of the connecting rod 24 is less than half the distance from the first hinge shaft 211 to the first rotating shaft 221.
[0077] It should be understood that the third telescopic unit 241 can be a mature product in the existing technology. For example, in this embodiment, considering that the welding torch 25 may need to be adjusted to slide along the connecting rod 24 during welding, a linear motor is used as the third telescopic mechanism to push the welding torch 25 to slide along the length direction of the connecting rod 24.
[0078] Accordingly, the welding robot provided in this embodiment, by slidingly connecting the welding torch 25 to the connecting rod 24, allows the distance between the welding torch 25 and the first rotating shaft 221 and the second rotating shaft 231 to be adjustable; furthermore, the welding robot provided in this embodiment can change the shape of the figure-eight trajectory (refer to...) by changing the distance between the welding torch 25 and the first rotating shaft 221 and the second rotating shaft 231. Figure 6 This alters the size of the arc-shaped trajectories at both ends of the figure-eight trajectory along its length, making one end larger and the other smaller. Accordingly, when the welding robot provided in this embodiment faces a curved seam trajectory, it can change the shape of the figure-eight trajectory by sliding the welding torch 25 along the length of the connecting rod 24 in the corner section of the seam. This makes the larger end of the figure-eight trajectory located outside the corner and the smaller end located inside the corner, thereby ensuring that both the inner and outer sides of the corner section are well filled by the molten pool.
[0079] In response, Figure 8A comparative schematic diagram of the motion of the welding assembly mechanism when the welding torch 25 moves along the length of the connecting rod 24 and deviates from the midpoint of the connecting rod 24 is drawn, where figure b (corresponding to Figure 4 ) and map sheet c (corresponding to Figure 6 In the figure, the lengths of all the rods are equal. The difference is that in figure b, the welding torch 25 is located at the midpoint of the connecting rod 24, while in figure c, the welding torch 25 slides toward the second rotating shaft 231 and deviates from the midpoint. Correspondingly, in figure b, the arcs at both ends of the figure-eight trajectory formed by the movement of the welding torch 25 are equal in length, while in figure c, the arcs at both ends of the figure-eight trajectory formed by the movement of the welding torch 25 are unequal in length, with the right end being larger than the left end. The lengths of the figure-eight trajectory formed by the movement of the welding torch 25 are equal.
[0080] Example 4:
[0081] This embodiment provides a control method for controlling the aforementioned welding robot to weld two workpieces to be joined together. The control method includes:
[0082] S1, Obtain the joint information of the two workpieces to be welded together, the joint information including the joint trajectory;
[0083] S2, control the moving component to drive the welding component to move, so that the tungsten electrode tip is located at a preset depth position of the joint, and the projection of the baseline in the vertical direction is located on the joint trajectory;
[0084] S3, control the moving component to drive the welding component to move, so that the projection of the baseline in the vertical direction moves along the joint trajectory and control the welding gun 25 to perform welding.
[0085] Accordingly, the control method provided in this embodiment can control the welding robot to continuously perform welding operations along the joint length direction, thereby completing the welding connection of the two workpieces to be welded.
[0086] Specifically, controlling the moving component to move the welding component includes:
[0087] Control the span frame 12 to slide along the first direction and control the telescopic frame 13 to slide along the second direction, so that the free end 132 translates in the horizontal direction;
[0088] Controlling the telescopic frame 13 to extend and retract in the vertical direction causes the free end 132 to translate in the vertical direction.
[0089] By controlling the sliding of the span 12 along the first direction and controlling the sliding of the telescopic frame 13 along the second direction, the motion trajectory of the projection of the baseline in the vertical direction can be controlled, thereby realizing the movement of the welding assembly along the joint trajectory.
[0090] Preferably, S3 includes:
[0091] When welding is performed at the bottom of the joint, the crank 22 is locked while the welding torch 25 is being controlled to perform welding.
[0092] When welding the upper part of the joint, the crank 22 is continuously rotated while the welding torch 25 is being controlled to perform welding, so that the welding torch 25 moves along the length of the joint and swings along the width of the joint.
[0093] Accordingly, the control method provided in this embodiment locks the crank 22 at the bottom of the weld joint, thereby adapting to the actual situation where the bottom of the weld joint is relatively narrow, and welds it by advancing along the weld joint. For the upper part of the weld joint, by controlling the crank 22 to rotate continuously, the tungsten electrode tip can move along the weld joint trajectory and swing in an 8-shaped trajectory along the width direction of the weld joint (the length direction of the 8-shaped trajectory is parallel to the normal direction of the weld joint). Thus, in the actual situation where the upper part of the weld joint is relatively wide, it can cover along the width direction. Therefore, the welding connection of deep weld joints can be completed in the form of multi-layer welding, avoiding the use of multi-layer multi-pass welding strategy (the "layer" of multi-layer multi-pass welding is formed by splicing multiple weld passes in the width direction. In the weld layer, there are often unfused points between multiple weld passes, forming interface defects). The overall integrity of the weld layer is good.
[0094] It should be understood that when locking crank 22, the tungsten electrode tip of welding torch 25 should be positioned on the baseline. This ensures that when the vertical projection of the control baseline moves along the joint trajectory, the tungsten electrode tip follows the joint trajectory, thus performing welding along the joint. In fact, the tungsten electrode tip of welding torch 25 can deviate from the baseline, but in this case, a correction factor needs to be introduced to compensate for the offset between the tungsten electrode tip and the baseline when the vertical projection of the control baseline moves along the joint trajectory. This ensures that the tungsten electrode tip always moves along the joint trajectory, avoiding weld misalignment. This would make it more complicated to slide the welding control frame 12 in the first direction and the control telescopic frame 13 in the second direction.
[0095] Preferably, S3 further includes:
[0096] S31, pre-connection: Determine multiple pre-connection points along the joint length direction (for example, number each pre-connection point sequentially as P1, P2, P3, P4, P5 along the joint length direction), and control the moving component to drive the welding component to move to each of the pre-connection points and perform spot welding.
[0097] The spot welding sequence is as follows: from the middle of the joint length direction to both ends, the pre-connection points are alternately welded (correspondingly, the spot welding sequence is: P3-P2-P4-P1-P5).
[0098] S32, segmented welding, the section between any two adjacent pre-connection points is identified as the section to be welded (correspondingly, each section to be welded is numbered sequentially along the joint length direction as: S 12 S 23 S 34 S 45 The moving component is controlled to drive the welding component to alternately weld sections from the middle to both ends along the joint length (correspondingly, the welding sequence of each section is: S). 23 -S 34 -S 12 -S 45 ).
[0099] Therefore, for welding of long joints, pre-connection can achieve the initial positioning work, and segmented welding can guide the release of welding stress, avoiding workpiece deformation caused by stress concentration under continuous welding of long joints.
[0100] Example 5:
[0101] This embodiment is based on embodiment 4, with the difference being that in this embodiment:
[0102] The joint information also includes joint depth, bevel angle, and root gap;
[0103] When welding the upper part of the joint, the first rotating shaft 221 is controlled to slide along the length direction of the crank 22 and the second rotating shaft 231 is controlled to slide along the length direction of the rotating rod 23, according to the joint depth, the bevel angle, the root gap and the depth of the welding position, so that the amplitude of the welding torch 25 swinging along the joint width direction is adapted to the joint width of the welding position.
[0104] Accordingly, the control method provided in this embodiment obtains the joint width of the welding position through the joint information, and then controls the first rotating shaft 221 to slide along the length direction of the crank 22 and controls the second rotating shaft 231 to slide along the length direction of the rotating rod 23, so as to change the constraint length of the crank 22 and the constraint length of the rotating rod 23 in the four-bar linkage composed of the frame 21, crank 22, rotating rod 23 and connecting rod 24 (it should be noted that the two are always equal), so that the length of the figure-eight trajectory formed by the tungsten electrode tip of the welding torch 25 under the newly obtained four-bar linkage constraint is adapted to the joint width of the welding position, thereby avoiding the situation that the weld layer formed at different welding depths is not fully welded or overflows in the width direction.
[0105] Specifically, for the V-shaped bevel, after controlling the first rotating shaft 221 to slide along the length direction of the crank 22, the distance from the first hinge shaft 211 to the first rotating shaft 221, and after controlling the second rotating shaft 231 to slide along the length direction of the rotating rod 23, the distance from the second hinge shaft 212 to the second rotating shaft 231, are obtained as follows:
[0106] ,
[0107] in, L 1 This indicates the distance from the first hinge shaft to the first rotating shaft after the first rotating shaft is controlled to slide along the length direction of the crank. L 2 This indicates the distance from the second hinge shaft to the second rotating shaft after the second rotating shaft has slid along the length of the rotating rod. H Indicates the seam depth. h Indicates the depth of the weld position. θ Indicates the bevel angle. d This indicates the root gap.
[0108] Accordingly, the control method provided in this embodiment can determine the required constraint lengths of the crank 22 and the rotating rod 23 based on the depth of the welding position, the joint depth, the bevel angle, and the root gap. Then, it controls the sliding of the first rotating shaft 221 and the second rotating shaft 231 according to the constraint lengths of the crank 22 and the rotating rod 23, thereby accurately controlling the sliding distance of the first rotating shaft 221 and the second rotating shaft 231 and greatly reducing the adjustment work in the process of controlling the sliding of the first rotating shaft 221 and the second rotating shaft 231 to the appropriate position.
[0109] Example 6:
[0110] This embodiment is based on embodiment 4, with the difference being that in this embodiment:
[0111] When welding the upper part of the joint, for the corner section of the joint, when controlling the welding gun 25 to perform welding, the frame 21 is controlled to rotate around the baseline so that the plane where the first hinge axis 211 and the second hinge axis 212 are located coincides with the normal of the joint trajectory of the corner section (for example, if the current welding position is a point P on the joint trajectory of the corner section, then the plane where the first hinge axis 211 and the second hinge axis 212 are located should coincide with the normal of the position where point P is located on the joint trajectory).
[0112] Accordingly, the control method provided in this embodiment can change the length direction of the figure-eight trajectory when the welding torch 25 swings by controlling the frame 21 to rotate around the baseline in the corner section of the joint, so that the length direction of the figure-eight trajectory always coincides with the normal direction of the joint trajectory in the welding position, which is beneficial to the welding corner section covering the width direction of the joint.
[0113] Specifically, when welding the upper part of the joint, for the corner section of the joint, when controlling the welding gun 25 to perform welding, the welding gun 25 is controlled to slide a preset distance outward along the length direction of the connecting rod 24 towards the corner, and the projection of the baseline in the vertical direction is controlled to slide a preset distance inward along the normal of the joint trajectory of the corner section towards the corner.
[0114] Obviously, during the welding process, the first hinge axis 211 and the second hinge axis 212 are located on both sides of the joint track, and controlling the welding torch 25 to slide a preset distance along the length of the connecting rod 24 toward the outside of the corner is actually controlling the welding torch 25 to slide along the length of the connecting rod 24. The direction of sliding is toward the hinge axis outside the joint track of the corner section (if the first hinge axis 211 is located outside the joint track, the welding torch 25 slides toward the first rotating axis 221; if the second hinge axis 212 is located outside the joint track, the welding torch 25 slides toward the second rotating axis 231).
[0115] Accordingly, the control method provided in this embodiment controls the welding torch 25 to slide along the length of the connecting rod 24 in the corner section of the joint, thereby changing the shape of the figure-eight trajectory of the welding torch 25 (making its two ends unequal in size), so that the larger end of the figure-eight trajectory is located on the outside of the corner section and the smaller end is located on the inside of the corner section. This can promote the distribution of more molten pool on the outside of the corner section and less on the inside of the corner section, thereby adapting to the difference in the amount of molten metal required on the outside and inside of the corner section, avoiding the situation of incomplete welding on the outside of the corner section and / or overflow on the inside. In addition, the control method also controls the projection of the baseline in the vertical direction to slide along the normal of the joint trajectory in the corner section towards the inside of the corner, thereby correcting the offset of the figure-eight trajectory of the welding torch 25 caused by the sliding welding torch 25 to the outside of the corner section, ensuring that the position covered by the welding torch 25 in the width direction of the joint is adapted to the joint position.
[0116] In this application, the term "seam track" refers to the center line of the seam.
[0117] In this application, the terms "rotatable installation" and "hinged connection" refer to two things that can only rotate relative to each other, such as the rotational arrangement of a hole and a shaft, which can restrict axial relative movement by providing a shoulder on the shaft and a limiting groove in the hole; the term "sliding connection" refers to two things that can only slide relative to each other, such as dovetail grooves, T-slots and other structures.
[0118] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A control method for a welding robot, used to control the welding robot to weld two workpieces to be joined together, characterized in that, The welding robot includes a moving component and a welding component; the welding component includes a frame (21), a crank (22), a rotating rod (23), a connecting rod (24), and a welding torch (25); one end of the connecting rod (24) is hinged to a first rotating shaft (221), and the other end is hinged to a second rotating shaft (231); the welding torch (25) is installed in the middle of the connecting rod (24); the moving component includes a slide rail (11), a strut frame (12), and a telescopic frame (13). The slide rail (11) is fixedly arranged along the first direction; the cross frame (12) is arranged along the second direction and is slidably connected to the slide rail (11), and the relative sliding direction of the two is parallel to the first direction; the telescopic frame (13) is vertically arranged and its fixed end (131) is slidably connected to the cross frame (12), and the relative sliding direction of the two is parallel to the second direction; The frame (21) is rotatably mounted on the free end (132) of the telescopic frame (13); one end of the crank (22) is hinged to the first hinge shaft (211) on the frame (21), and a first rotating shaft (221) is provided on the other end of the crank (22); one end of the rotating rod (23) is hinged to the second hinge shaft (212) on the frame (21), and a second rotating shaft (231) is provided on the other end of the rotating rod (23). The distance from the first hinge shaft (211) to the first rotating shaft (221) is equal to the distance from the second hinge shaft (212) to the second rotating shaft (231), and the crank (22) and the rotating rod (23) rotate in opposite directions, so that when the crank (22) rotates continuously, the tungsten electrode tip of the welding torch (25) moves in a figure-eight trajectory; The axis of rotation of the frame (21) relative to the free end (132) is defined as the baseline. The baseline is vertical and the intersection of the figure-eight trajectory is located on the baseline when the welding torch (25) is located at the midpoint of the connecting rod (24). The first rotating shaft (221) is slidably connected to the crank (22) and the direction in which they slide relative to each other is parallel to the length direction of the crank (22). A first telescopic unit (222) is installed on the crank (22) and the first telescopic unit (222) is used to push the first rotating shaft (221) to slide. The second rotating shaft (231) is slidably connected to the rotating rod (23), and the direction of their relative sliding is parallel to the length direction of the rotating rod (23). A second telescopic unit (232) is installed on the rotating rod (23), and the second telescopic unit (232) is used to push the second rotating shaft (231) to slide. The welding torch (25) is slidably connected to the connecting rod (24), and the direction of their relative sliding is parallel to the length direction of the connecting rod (24). A third telescopic unit (241) is installed on the connecting rod (24), and the third telescopic unit (241) is used to push the welding torch (25) to slide. The distance between the axis of the welding torch (25) and the midpoint of the connecting rod (24) is less than half the distance from the first hinge shaft (211) to the first rotating shaft (221); The control method includes: S1, Obtain the joint information of the two workpieces to be welded together, the joint information including the joint trajectory; S2, control the moving component to drive the welding component to move, so that the tungsten electrode tip is located at a preset depth position of the joint, and the projection of the baseline in the vertical direction is located on the joint trajectory; S3, control the moving component to drive the welding component to move, so that the projection of the baseline in the vertical direction moves along the joint trajectory and control the welding gun (25) to perform welding; S3 includes: When welding is performed at the bottom of the joint, the crank (22) is locked while the welding torch (25) is controlling the welding to perform the welding. When welding the upper part of the joint, the crank (22) is continuously rotated while the welding gun (25) is controlled to perform welding, so that the welding gun (25) moves along the joint length direction and swings along the joint width direction at the same time. The joint information also includes joint depth, bevel angle, and root gap; When welding the upper part of the joint, the first rotating shaft (221) is controlled to slide along the length direction of the crank (22) and the second rotating shaft (231) is controlled to slide along the length direction of the rotating rod (23) according to the joint depth, the bevel angle, the root gap and the depth of the welding position, so that the amplitude of the welding gun (25) swinging along the joint width direction is adapted to the joint width of the welding position; For the V-shaped bevel, after controlling the first rotating shaft (221) to slide along the length direction of the crank (22), the distance from the first hinge shaft (211) to the first rotating shaft (221), and after controlling the second rotating shaft (231) to slide along the length direction of the rotating rod (23), the distance from the second hinge shaft (212) to the second rotating shaft (231) is obtained as follows: ， in, L 1 This indicates the distance from the first hinge shaft to the first rotating shaft after the first rotating shaft is controlled to slide along the length direction of the crank. L 2 This indicates the distance from the second hinge shaft to the second rotating shaft after the second rotating shaft has slid along the length of the rotating rod. H Indicates the seam depth. h Indicates the depth of the weld position. θ Indicates the bevel angle. d This indicates the root gap.
2. The control method according to claim 1, characterized in that: The control of the moving component to drive the welding component to move includes: Control the span frame (12) to slide along the first direction and control the telescopic frame (13) to slide along the second direction, so that the free end (132) translates in the horizontal direction; Controlling the telescopic frame (13) to extend and retract in the vertical direction causes the free end (132) to translate in the vertical direction.
3. The control method according to claim 1, characterized in that: S3 includes: S31, Pre-connection: Determine multiple pre-connection points along the joint length direction, and control the moving component to drive the welding component to each of the pre-connection points and perform spot welding; The spot welding sequence is as follows: alternating between pre-connected points from the middle to both ends along the length of the joint; S32, segmented welding, the section between any two adjacent pre-connection points is identified as the section to be welded, and the moving component is controlled to drive the welding component to alternately weld the sections to be welded from the middle to both ends of the joint length direction.
4. The control method according to claim 1, characterized in that: When welding is performed on the upper part of the joint, for the corner section of the joint, when the welding gun (25) is controlled to perform welding, the frame (21) is controlled to rotate around the baseline so that the plane where the first hinge axis (211) and the second hinge axis (212) are located coincides with the normal of the joint trajectory of the corner section.
5. The control method according to claim 4, characterized in that: When welding is performed on the upper part of the joint, for the corner section of the joint, when the welding gun (25) is controlled to perform welding, the welding gun (25) is controlled to slide a preset distance outward along the length direction of the connecting rod (24) towards the corner, and the projection of the baseline in the vertical direction is controlled to slide a preset distance inward along the normal of the joint trajectory of the corner section towards the corner.
6. The control method according to claim 1, characterized in that: The welding torch (25) is tilted, and the axis of the welding torch (25) forms an angle of 10° to 20° with the baseline.
7. The control method according to claim 1, characterized in that: A counterweight is installed on the rotating rod (23), and the center of gravity of the counterweight is eccentric to the second hinge shaft (212).
8. The control method according to claim 1, characterized in that: A first motor (111) is fixedly installed on the slide rail (11), and a first screw (112) is rotatably installed on the slide rail (11). The cross frame (12) is threadedly connected to the first screw (112), and the first motor (111) is used to drive the first screw (112) to rotate. A second motor (121) is fixedly installed on the span frame (12), and a second screw (122) is rotatably installed on the span frame (12). The fixed end (131) is threadedly connected to the second screw (122), and the second motor (121) is used to drive the second screw (122) to rotate. A third motor (133) is fixedly installed on the fixed end (131), and a third screw (134) is rotatably installed on the fixed end (131). The free end (132) is threadedly connected to the third screw (134), and the third motor (133) is used to drive the third screw (134) to rotate.
9. The control method according to claim 1, characterized in that: A first drive motor (135) is fixedly installed on the free end (132), and the first drive motor (135) is used to drive the frame (21) to rotate; The first drive motor (135) is a servo motor.
10. The control method according to claim 1, characterized in that: A first drive motor (135) is fixedly installed on the free end (132), and the first drive motor (135) is used to drive the frame (21) to rotate; The first drive motor (135) is a stepper motor.