Automatic welding method and device for cabinet sheet metal

Abstract

The present application relates to the technical field of industrial automation welding, and discloses an automatic welding method and device for cabinet sheet metal. The present application aims to solve the problem that the existing welding equipment lacks a joint self-adaptive adjustment mechanism, which easily leads to thin plate burning, edge melting and deformation induced by heat accumulation caused by continuous welding. The present application feeds forward to plan the visual collection area to extract the gap width and the edge deviation; in response to the widening of the gap, the wire feeding and moving speed are adjusted cooperatively to maintain the constant heat input per unit length; in response to the edge deviation exceeding the tolerance, the welding gun is controlled to be laterally offset and asymmetrically swung to guide the heat source to concentrate on the low side of the bearing surface; the step heat input is continuously accumulated, and when approaching the deformation critical point, the voltage is lowered, the speed is increased, and the follow-up cooling device is activated to direct cooling of the heat affected zone.

Description

Technical Field

[0001] This invention relates to the field of industrial automated welding technology, and more specifically, to an automatic welding method and apparatus for cabinet sheet metal. Background Technology

[0002] This invention relates to the field of industrial automated welding technology, specifically to an automated welding method and apparatus for sheet metal cabinets. With the continuous advancement of intelligent manufacturing, industrial robots and automated welding machines have been widely used in the assembly and manufacturing of sheet metal structures such as chassis and electrical control cabinets. Typically, cabinet products are constructed from thin-walled materials such as thin-rolled steel sheets, requiring extremely high precision in terms of surface flatness, weld continuity, and overall structural rigidity. Existing automated welding equipment largely relies on pre-taught fixed trajectories and preset constant welding parameters for assembly line operations, or is only equipped with basic vision tracking systems to correct the welding torch's path.

[0003] However, in actual batch processing of sheet metal for server racks, due to the unavoidable processing tolerances in the preceding bending, shearing, and assembly processes, long-distance seams often exhibit physical defects such as fluctuating gap widths and localized misalignments. Traditional automated welding equipment, lacking an adaptive adjustment mechanism for changes in seam morphology, continues to output constant arc heat and filler material when faced with widening gaps or severe misalignments, easily leading to serious forming defects such as burn-through of thin plates or collapse of suspended edges. Furthermore, due to the good thermal conductivity of metals, under prolonged and continuous welding of thin plates, the heat input easily accumulates residual stress in the later stages of the weld, inducing irreversible wavy thermal deformation. Existing methods struggle to balance the forming quality of complex gaps with the control of overall thermal deformation, resulting in high product scrap rates or requiring significant labor costs for post-weld straightening. Therefore, there is an urgent need in this field to solve the aforementioned technical problems. Summary of the Invention

[0004] In view of the aforementioned problems with existing welding equipment, such as the lack of an adaptive adjustment mechanism for seams, which easily leads to burn-through of thin plates, misalignment and collapse, and deformation induced by heat accumulation during continuous welding, the present invention provides the following technical solution to address these issues:

[0005] This invention provides an automatic welding method for sheet metal cabinets, which includes the following steps:

[0006] S1: The main control computer plans the laser scanning data acquisition frame in advance based on the walking speed and direction of the multi-axis linear moving mechanism, and obtains the point cloud data in the data acquisition frame through the single-line laser contour sensor set in front of the arc welding gun, and calculates the actual gap width of the cabinet sheet metal splice and the height difference between the two sheet metal pieces.

[0007] S2: The main control computer synchronously sends control commands to the digitally controlled welding machine and the multi-axis linear motion mechanism based on the change in the actual gap width. While increasing the wire feeding speed of the welding machine, the traveling speed of the multi-axis linear motion mechanism is increased proportionally.

[0008] S3: The main control computer controls the arc welding gun to shift towards the lower sheet metal side according to the height difference, and controls the arc welding gun to increase the dwell time on the lower sheet metal side when swinging left and right.

[0009] S4: The main control computer accumulates the total heat output to the sheet metal in real time throughout the welding process. When the total heat reaches the preset deformation critical point, it sends a voltage reduction command to the digitally controlled welding machine, increases the walking speed of the multi-axis linear movement mechanism, and activates the follow-up cooling nozzle located behind the arc welding gun for targeted cooling.

[0010] As a preferred embodiment of the automatic welding method for cabinet sheet metal of the present invention, the specific process of the feedforward planning of the dynamic acquisition area of ​​the vision sensor in S1 is as follows: the main control computer obtains the current motion parameters of the moving actuator and the sampling period of the vision sensor, predicts the physical position range of the area to be welded at the next moment based on the current motion parameters and the sampling period, and delineates the dynamic acquisition area based on the physical position range, thereby controlling the vision sensor to only extract and process the contour data inside the dynamic acquisition area, and shielding the ambient light and splash interference outside the area.

[0011] As a preferred embodiment of the automatic welding method for sheet metal cabinets described in this invention, the specific process of calculating the actual gap width and misalignment difference of the sheet metal joint in S1 is as follows: the main control computer extracts the spatial height difference between adjacent data points in the dynamic acquisition area, removes abnormal interference points with abrupt change characteristics by setting a height difference change threshold, then fits the remaining contour point cloud data to obtain flat line segments representing the surfaces of the two sheet metal pieces, and extracts the discontinuous endpoints of the flat line segments as actual physical edges, then obtains the actual gap width by calculating the horizontal distance between the two actual physical edges, and obtains the misalignment difference by calculating the vertical distance between the two flat line segments.

[0012] As a preferred embodiment of the automatic welding method for cabinet sheet metal of the present invention, the specific process of increasing the wire feeding rate of the welding machine in S2 is as follows: in response to the detection that the actual gap width is increasing, the main control computer calculates the additional metal deposition amount required to fill the current incremental gap based on the principle of volume conservation, combined with the widened gap size and the preset welding wire specifications, and issues a corresponding speed-up command to the wire feeding actuator of the welding machine, and outputs welding wire matching the additional metal deposition amount per unit time.

[0013] As a preferred embodiment of the automatic welding method for cabinet sheet metal described in this invention, the specific process of coordinating the increase of the walking speed of the moving actuator in S2 is as follows: the main control computer calculates the target moving speed required to maintain a constant heat input per unit length of sheet metal based on the additional arc heat input caused by the increase in wire feeding rate and the allowable thermal deformation threshold of the sheet metal material, and synchronously drives the moving actuator to accelerate to the target moving speed, thereby offsetting the additional arc heat input by shortening the time the heat source acts on the unit path.

[0014] As a preferred embodiment of the automatic welding method for cabinet sheet metal described in this invention, the specific process of controlling the energy center of the welding gun to laterally shift to the lower sheet metal side in step S3 is as follows: in response to the misalignment difference exceeding the set tolerance range, the main control computer calculates the lateral shift distance to avoid the high suspended edge, and drives the moving actuator to move the welding gun laterally by the lateral shift distance, so that the energy center of the welding gun deviates from the original joint center, and is transferred and aligned with the bearing surface of the lower sheet metal.

[0015] As a preferred embodiment of the automatic welding method for cabinet sheet metal described in this invention, the specific process of allocating a larger dwell time ratio to the lower sheet metal side in step S3 is as follows: when driving the welding gun to perform lateral oscillation welding, the main control computer performs asymmetrical time allocation of the oscillation cycle, so that the dwell time ratio of the welding gun on the lower sheet metal surface is greater than the sweeping time ratio on the higher sheet metal edge, guiding the heat source and molten pool to preferentially adhere to the lower bearing surface, and relying on the heat attached by the sweeping action to achieve adhesion and fusion of the higher edge.

[0016] As a preferred embodiment of the automatic welding method for cabinet sheet metal of the present invention, the specific process of calculating the cumulative heat input during the continuous integration calculation in S4 is as follows: the main control computer synchronously collects the real-time output current, real-time output voltage of the welding machine and the real-time walking speed of the moving actuator according to discrete time steps. By performing product integration on the real-time output current, the real-time output voltage and the real-time walking speed, the step input line energy corresponding to the time step is obtained. All the step input line energies from the welding start point to the current position are accumulated to obtain the cumulative heat input reflecting the current cumulative heating state of the sheet metal.

[0017] As a preferred embodiment of the automatic welding method for cabinet sheet metal of the present invention, the specific process of reducing the output energy parameter of the welding machine and further increasing the walking speed of the moving actuator in step S4, while simultaneously activating the follow-up cooling device, is as follows: when the welding torch travels to the preset weld seam rear section and the cumulative heat input is detected to be close to the deformation critical point, the main control computer, while maintaining the existing wire feeding amount unchanged, reduces the output voltage of the welding machine according to a preset gradient as a means of reducing the output energy parameter, and at the same time issues an acceleration command to the moving actuator again to move away from the high temperature affected area as soon as possible, and simultaneously activates the follow-up cooling device that follows the movement of the welding torch to spray cooling medium in a directional manner onto the residual heat affected area after welding.

[0018] The present invention also provides an automatic welding device for cabinet sheet metal, used to perform the above method, specifically including:

[0019] A moving unit includes a base, with transverse guide rails arranged parallel to each other on both sides of the base, a longitudinal beam slidably mounted on the transverse guide rails, a Z-axis slider slidably mounted on the longitudinal beam, a load-bearing beam slidably mounted on the Z-axis slider, and a clamping device provided on the base.

[0020] The welding unit includes a connecting seat on the supporting crossbeam, a wire feeding motor on the connecting seat, a wire feeding mechanism connected to the bottom end of the wire feeding motor, a wire guide tube connected to the output end of the wire feeding mechanism, and an arc welding gun on one side of the wire guide tube.

[0021] The auxiliary control unit includes a wire guide tube and a fixed bracket on the arc welding gun. One end of the fixed bracket is connected to a suspension bracket, a laser profile sensor is installed on the suspension bracket, and a cooling nozzle is installed on the other end of the fixed bracket.

[0022] The beneficial effects of this invention are as follows: Based on the dynamic and coordinated adjustment of wire feeding and moving speed according to the conservation of volume and linear energy, and controlling the heat source to shift towards the lower side of the misaligned edge, this invention effectively avoids the risk of burn-through of the thin plate of the cabinet and melt collapse of the suspended edge; at the same time, through high-frequency discrete accumulation of real-time heat input, when approaching the deformation critical point, it coordinates the execution of pressure reduction, speed increase and targeted physical cooling in the rear, cutting off the longitudinal accumulation of thermal stress; in addition, relying on the rigid follow-up integrated hardware structure of front viewing, middle welding and rear blowing, it eliminates the mechanical delay of multi-axis linkage, and provides a solid guarantee for the accurate implementation of adaptive seam finding and cooling algorithms. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 Flowchart of an automated welding method for server rack sheet metal.

[0025] Figure 2 Flowchart of the decoupling compensation logic for gap widening.

[0026] Figure 3 Flowchart of global thermal control closed loop to prevent deformation.

[0027] Figure 4 This is a logical block diagram of the control system software architecture.

[0028] Figure 5 This is an overall view of the automatic welding device used for cabinet sheet metal.

[0029] Figure 6 A partial view of the automatic welding device used for cabinet sheet metal. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "example" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The appearance of an embodiment in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0033] Example 1

[0034] Reference Figures 1-3 As one embodiment of the present invention, this embodiment provides an automatic welding method for sheet metal cabinets, comprising the following steps:

[0035] S1, the main control computer plans the laser scanning data acquisition frame in advance according to the walking speed and direction of the multi-axis linear moving mechanism, and obtains the point cloud data in the data acquisition frame through the single-line laser contour sensor set in front of the arc welding gun, and calculates the actual gap width of the cabinet sheet metal splice and the height difference between the two sheet metal pieces.

[0036] The main control computer acquires the current motion parameters of the mobile actuator and the sampling period of the vision sensor. Based on the current motion parameters and sampling period, it predicts the physical position range of the area to be welded at the next moment, and delineates the dynamic acquisition area based on the physical position range. Then, it controls the vision sensor to extract and process only the contour data inside the dynamic acquisition area, shielding the ambient light and spatter interference outside the area.

[0037] The main control computer extracts the spatial height difference between adjacent data points in the dynamic acquisition area. By setting a height difference change threshold, abnormal interference points with abrupt change characteristics are removed. Then, the remaining contour point cloud data is fitted to obtain flat line segments representing the surfaces of two sheet metal pieces. The discontinuous endpoints of the flat line segments are extracted as actual physical edges. The actual gap width is obtained by calculating the horizontal distance between the two actual physical edges, and the misalignment difference is obtained by calculating the vertical distance between the two flat line segments.

[0038] In actual automated welding environments for server racks, the intense light from the electric arc and metal spatter can severely interfere with visual recognition. The main control computer calculates the distance traveled per second and the coordinate system direction of the moving mechanism by real-time reading of the encoder data from the three-axis slide table. Combined with the number of frames captured per second by the sensors, it accurately predicts the imaging position of the weld seam in the next frame. Based on this position, the system internally defines a very small virtual rectangle (i.e., a dynamically enclosing area) that moves synchronously with the welding torch. The sensors only retain image data within this rectangle, physically shielding most of the intense light and spatter noise interference outside the frame.

[0039] After acquiring local point cloud data, the system compares the height values ​​of adjacent data points one by one. The system pre-sets a threshold for height difference changes (for example, for a relatively flat cold-rolled steel plate for a server rack, the allowable normal fluctuation range is set to within 0.2 mm). If the height value shows a drastic, abrupt increase, and the height difference between adjacent points exceeds this preset fluctuation range of 0.2 mm, the system determines that the point is a flying metal splatter or a point of strong arc reflection (i.e., an abnormal interference point exhibiting abrupt changes) and deletes it. After noise removal, the originally messy data is restored to line segments representing the flat surface of the cold-rolled steel plate (i.e., flat line segments). The break between these two flat line segments is the actual edge of the plate. The system measures the horizontal distance and vertical drop between these two edges, thereby dynamically outputting the current gap width and misalignment height at millisecond-level frequencies.

[0040] S2, the main control computer synchronously sends control commands to the digitally controlled welding machine and the multi-axis linear motion mechanism based on the actual change in the gap width, increasing the wire feeding speed of the welding machine while proportionally increasing the travel speed of the multi-axis linear motion mechanism.

[0041] In response to the detected trend of increasing actual gap width, the main control computer, based on the principle of volume conservation, combined with the widened gap size and the preset welding wire specifications, calculates the additional metal deposition required to fill the current incremental gap, and sends a corresponding speed-up command to the wire feeding actuator of the welding machine, outputting welding wire matching the additional metal deposition within a unit time.

[0042] The main control computer calculates the target moving speed required to maintain a constant heat input per unit length of sheet metal based on the additional arc heat input caused by the increase in wire feeding rate and the allowable thermal deformation threshold of the sheet metal material. It then synchronously drives the moving actuator to accelerate to the target moving speed, thereby offsetting the additional arc heat input by shortening the time the heat source acts on the unit path.

[0043] The gaps between the cabinet components often fluctuate in width. When the calculated gap widens, the main control computer uses a built-in wire feeding compensation algorithm to precisely calculate the additional volume of molten metal required. During the calculation, the system directly calls the preset welding wire specification (e.g., the welding machine is currently loaded with a solid carbon steel welding wire with a diameter of 0.8 mm). The specific formula is as follows:

[0044]

[0045] in, For the target wire feed speed that needs to be adjusted, To determine the actual gap width, The thickness of the cabinet sheet metal. At the current walking speed, The radius of the cross-section of the metal welding wire used. After the calculation is completed, the system immediately sends an acceleration command to the micro motor (i.e., the wire feeding actuator) responsible for clamping and feeding the welding wire outward, to ensure that the amount of welding wire output can fully fill the widening gap.

[0046] Increased wire feeding speed leads to a significant synchronous increase in welding current. To prevent thinner sheet metal from being damaged by the surge in current, the main control computer immediately initiates thermal balance compensation calculations, taking into account the maximum heat that a cold-rolled steel sheet of a specific thickness can withstand before irreversible thermal deformation (i.e., the allowable thermal deformation threshold). The target's moving speed is calculated using the following formula:

[0047]

[0048] in, For the target movement speed, The electric arc thermal efficiency coefficient, and These are the welding voltage and current collected in real time, respectively. The allowable thermal deformation threshold is defined. By forcibly increasing the walking speed, the time the high-temperature heat source acts on the sheet metal is shortened, enabling high-current fast welding. This satisfies the need to fill gaps while preventing heat from concentrating and burning through the sheet metal.

[0049] S3, the main control computer controls the arc welding gun to shift towards the lower sheet metal side according to the height difference, and controls the arc welding gun to increase the dwell time on the lower sheet metal side when swinging left and right.

[0050] In response to the misalignment exceeding the set tolerance range, the main control computer calculates the lateral offset distance to avoid the high, overhanging edge, and drives the moving actuator to move the welding torch laterally by the lateral offset distance, so that the energy center of the welding torch deviates from the original joint center, and is transferred and aligned with the bearing surface of the sheet metal that is in a lower position.

[0051] When the welding torch is driven to perform lateral oscillation welding, the main control computer performs asymmetrical time allocation of the oscillation cycle, so that the ratio of the dwell time of the welding torch on the sheet metal surface at a lower position is greater than the ratio of the sweeping time on the sheet metal edge at a higher position. This guides the heat source and molten pool to preferentially adhere to the bearing surface on the lower side, and relies on the heat attached by the sweeping action to achieve adhesion and fusion of the higher edge.

[0052] When two assembled panels are misaligned, the exposed right-angled edge of the higher panel is highly susceptible to melting due to the lack of bottom support. The system's internal tolerance range is typically one-quarter of the panel thickness (for example, for a 2mm thick cabinet panel, if the height difference of the misaligned edge exceeds 0.5mm, it is considered to be outside the set tolerance range). After calculating the offset, the system controls the welding torch to move horizontally towards the lower panel, ensuring that the central area with the highest temperature and most concentrated energy within the arc (i.e., the energy center axis) avoids the higher edge and directly targets the bottom panel surface, utilizing the thicker bottom panel to absorb the main high-temperature impact.

[0053] When the welding torch performs left-right oscillation welding, the system takes over the control of the servo motor and no longer distributes the oscillation time equally. The system controls the welding torch to stay on the lower plate for a longer time (for example, set to account for 70% of the entire oscillation cycle), so that the molten metal accumulates preferentially on the bottom plate; when the welding torch oscillates over the higher edge, it is controlled to quickly sweep over it (accounting for only 30% of the cycle), using only the brief residual heat during the sweep to fuse the bottom molten pool with the higher edge, effectively eliminating the risk of the higher thin plate edge being directly melted and collapsed by high temperature.

[0054] S4, the main control computer accumulates the total heat output to the sheet metal in real time throughout the welding process. When the total heat reaches the preset deformation critical point, it sends a command to the digitally controlled welding machine to reduce the voltage. At the same time, it increases the walking speed of the multi-axis linear movement mechanism and starts the follow-up cooling nozzle located behind the arc welding gun for targeted cooling.

[0055] The main control computer synchronously collects the real-time output current and voltage of the welding machine and the real-time walking speed of the moving actuator according to discrete time steps. By multiplying and integrating the real-time output current, real-time output voltage and real-time walking speed, the corresponding step input line energy within the time step is obtained. All step input line energies from the welding start point to the current position are accumulated to obtain the cumulative heat input reflecting the current cumulative heating state of the sheet metal.

[0056] When the welding torch travels to the preset weld seam rear section and the cumulative heat input is detected to be close to the deformation critical point, the main control computer, while maintaining the existing wire feeding amount, adjusts the output voltage of the welding machine according to the preset gradient as a means of reducing the output energy parameter. At the same time, it sends an acceleration command to the moving actuator to move away from the high temperature affected zone as soon as possible, and simultaneously activates the follow-up cooling device that moves with the welding torch to spray cooling medium in a directional manner into the residual heat affected zone after welding.

[0057] Due to the high thermal conductivity of metals, long-distance welding can easily lead to heat accumulation at the rear of the weld, causing deformation. The main control computer divides the continuous welding process into extremely short time intervals (e.g., every 10 milliseconds as a discrete time step), and calculates in real time the actual amount of heat (in Joules) input by the arc into the plate within that specific time step. The core formula is:

[0058]

[0059] Where $Q_{total}$ represents the total heat input accumulated since the start of welding. , and The first Real-time output voltage, real-time output current, and real-time walking speed within a time step. This refers to the physical distance (i.e., the walking step) traveled by the moving actuator within this time step. This represents the total number of steps taken from the start of the welding process to the current position. The system continuously accumulates the actual heat injected in each segment since the welding began, resulting in accurate cumulative heat data for the entire cabinet process.

[0060] When the arc welding torch travels to the preset section of the weld seam (e.g., the last third of the entire weld seam, where the heat conduction from the front is most intense), and the system detects that the accumulated total heat is approaching the critical deformation point, the system, in order to ensure that the weld seam filling amount meets the standard, resolutely does not change the wire feed speed, but instead uses three methods to cool down in a coordinated manner: First, the output voltage is steadily reduced according to a preset gradient (e.g., automatically deducting 0.5 volts every 100 milliseconds) to weaken the penetrating power of the arc; second, the moving mechanism is accelerated to allow the welding torch to move away from the high-temperature area as quickly as possible; finally, the follow-up cooling nozzle located behind the welding torch is opened simultaneously to directionally spray compressed argon or liquid nitrogen mixed cold air (i.e., cooling medium) onto the heat-affected zone that has just been welded and is in a red-hot state.

[0061] By combining the reduction of arc heat, acceleration of movement, and external physical cooling, residual thermal stress is effectively suppressed, enabling the non-alignment processing of long-distance thin plate welds.

[0062] Example 2

[0063] Reference Figure 4 This is the second embodiment of the present invention, which provides an automatic welding system for cabinet sheet metal, which is typically deployed on a high-performance computing server to perform the method steps in embodiment 1.

[0064] The system's software architecture consists of a set of highly collaborative functional modules, specifically including:

[0065] The visual seam finding and feature extraction module feeds forward the dynamic acquisition area of ​​the visual sensor based on the real-time motion parameters of the mobile actuator, and extracts the contour point cloud data within the dynamic acquisition area to calculate the actual seam width and misalignment difference of the sheet metal joint.

[0066] The gap widening decoupling compensation module, in response to the detection that the actual gap width is increasing, synchronously generates wire feeding compensation instructions and speed coordination instructions. While increasing the wire feeding rate of the welding machine, it also coordinates to increase the walking speed of the moving actuator, maintaining a constant heat input per unit length of sheet metal.

[0067] The edge misalignment adjustment module responds to the edge misalignment exceeding the set tolerance range by controlling the energy center of the welding torch to shift laterally to the lower sheet metal side, and allocates a larger dwell time ratio to the lower sheet metal side when driving the welding torch to perform lateral oscillation welding.

[0068] The global thermal control and anti-deformation intervention module continuously integrates and calculates the cumulative heat input during the welding process. When the cumulative heat input approaches the preset deformation critical point, it lowers the output energy parameters of the welding machine and further increases the walking speed of the moving actuator. At the same time, it activates the follow-up cooling device to force cooling of the heat-affected zone.

[0069] The system's operation begins with the visual seam detection and feature extraction module's initial mapping of the physical environment. This module reads the current 3D coordinates and velocity vectors by real-time input to the encoder feedback data from the underlying driver of the moving actuator. Combining this with the inherent sampling period of the visual sensor, it feeds forward to deduce the physical position range for the next cycle. Based on this range, the module delineates a dynamic acquisition area within a unified world coordinate system, encompassing a small region in front of the weld seam, and controls the visual sensor to retain only the optical echo signal within this area. Furthermore, the module performs spatial height difference comparison on the point cloud data received within this area, eliminating abnormal interference points where the height difference exceeds a preset threshold. The cleaned high-fidelity data points are then fitted into flat line segments. Finally, through endpoint analysis, a high-precision calculation of the actual seam width and misalignment difference is performed, establishing the data benchmark for subsequent adaptive adjustments.

[0070] In addressing fluctuations in assembly gaps, the gap widening decoupling compensation module establishes a high-speed data command channel. Responding to the detected increasing trend in the actual gap width, this module invokes preset welding wire geometry parameters and, based on spatial volume conservation logic, calculates the additional metal deposition required to fill the current incremental gap. It then directly sends an acceleration control pulse to the wire feeding actuator of the digital welding machine. Simultaneously, to counteract the heat generated by the high current, the module calculates the target moving speed required to maintain constant target linear energy in real time, based on the additional arc heat input from the increased wire feeding speed and the allowable thermal deformation threshold of the sheet metal material. This speed is then used to drive the motors of each axis of the moving actuator to accelerate collaboratively. By shortening the duration of the high-temperature heat source's action on the unit path, it perfectly counteracts the surge in destructive heat caused by the increased filling volume.

[0071] To ensure welding quality under complex assembly tolerances, the edge misalignment adaptive adjustment module continuously verifies the input edge misalignment data. In response to the edge misalignment exceeding the set tolerance range, the module calculates a lateral offset vector to avoid the thin edge at a higher position and sends a position fine-tuning command to the moving actuator. This drives the welding torch's energy center to physically deviate from the original seam center, precisely aligning it with the lower sheet metal surface. When performing lateral oscillating welding, the module directly intervenes in the underlying servo control loop, reconstructing the timing distribution matrix of the oscillation cycle. This assigns the welding torch a pre-set high dwell time on the lower sheet metal surface and controls it to perform a rapid sweeping motion when passing over the higher, overhanging edge, relying on the residual heat from the sweeping motion to achieve adhesion and fusion of the higher edge.

[0072] Throughout the entire welding lifecycle, the global thermal control and anti-deformation intervention module forms an ultimate physical cooling closed loop. This module operates at high frequency in the background, synchronously capturing the welding machine's real-time output current, real-time output voltage, and the real-time travel speed of the moving actuator according to a preset discrete time step. It calculates the real-time linear energy by multiplying the voltage and current by the speed, and continuously accumulates all real-time linear energy since the start of welding, combined with the travel step. When the welding torch reaches a preset weld seam extension section, and the system detects that the accumulated heat input is approaching a preset deformation critical point, the module forcibly takes over control. While maintaining the existing wire feed to ensure structural strength, it lowers the welding machine's output voltage according to a preset gradual decrease gradient to weaken the arc rigidity. Simultaneously, it issues a secondary acceleration command to the moving actuator to quickly move it away from the high-temperature danger zone, and simultaneously outputs a high-level trigger signal to the follow-up cooling device to target and spray cooling media into the residual heat-affected zone. Through the triple linkage of source reduction, time compression, and physical rapid cooling, the longitudinal accumulation chain of thermal stress is successfully severed.

[0073] Example 3

[0074] Reference Figure 5 and Figure 6This is the third embodiment of the present invention. This embodiment provides an automatic welding device for cabinet sheet metal, which is used to perform the method described in the first embodiment and serves as the hardware execution carrier of the system described in the second embodiment.

[0075] Specifically, it includes:

[0076] The moving unit 100 includes a base 101, with transverse guide rails 102 arranged parallel to both sides of the base 101, a longitudinal crossbeam 103 slidably mounted on the transverse guide rails 102, a Z-axis slider 104 slidably mounted on the longitudinal crossbeam 103, a load-bearing crossbeam 105 slidably mounted on the Z-axis slider 104, and a clamping device 106 provided on the base 101.

[0077] Welding unit 200 includes a connecting seat 201 on a supporting crossbeam 105, a wire feeding motor 202 on the connecting seat 201, a wire feeding mechanism 203 connected to the bottom end of the wire feeding motor 202, a wire guide tube 204 connected to the output end of the wire feeding mechanism 203, and an arc welding gun 205 on one side of the wire guide tube 204.

[0078] The auxiliary control unit 300 includes a wire guide tube 204 and a fixed bracket 301 on the arc welding gun 205. One end of the fixed bracket 301 is connected to a suspension bracket 302, and a laser profile sensor 303 is installed on the suspension bracket 302. The other end of the fixed bracket 301 is provided with a cooling nozzle 304.

[0079] Before performing the cabinet sheet metal welding operation, the cabinet sheet metal to be welded is placed on the base 101 and stably clamped and positioned by the clamping device 106 to prevent the cabinet sheet metal from shifting position during subsequent processing and heating.

[0080] The transverse guide rail 102 and the longitudinal beam 103 work together with the Z-axis slider 104, which is driven by an external servo drive component to move linearly in three-dimensional space to adjust the position of the Z-axis slider 104 and the load-bearing beam 105 slidably connected to the Z-axis slider 104, thereby driving the welding unit 200 and the auxiliary control unit 300 to accurately reach the three-dimensional starting position of the cabinet seam.

[0081] After the device is positioned, the laser contour sensor 303 begins to monitor the weld seam directly in front of the arc welding gun 205, acquires the contour point cloud data of the cabinet sheet metal, and transmits the information to the system for processing.

[0082] After the system identifies and calculates the width of the gap and the difference in edge height ahead, the moving unit 100 drives the entire structure to move along the weld direction. During welding operations, the wire feeding motor 202 drives the wire feeding mechanism 203 to feed the thin welding wire through the short-distance wire guide tube 204 into the arc welding torch 205. Since the wire feeding motor 202 is directly and vertically arranged above the arc welding torch 205, the wire feeding path is greatly shortened, effectively avoiding bending and jamming of the thin welding wire commonly used in cabinet thin plate welding during long-distance transportation, and ensuring that the wire feeding action is smooth and lag-free when the system issues a speed-up command.

[0083] The rigid fixation of the fixed bracket 301 to the wire guide tube 204 and the arc welding torch 205 creates a high-strength follow-up connection between the laser profile sensor 303, the arc welding torch 205, and the cooling nozzle 304. As the supporting beam 105 moves, the laser profile sensor 303 always scans the original seam that has not yet been damaged by the arc light in advance, while the cooling nozzle 304 always precisely points behind the welding residual heat-affected zone that the arc welding torch 205 has just left.

[0084] In summary, this invention dynamically and collaboratively adjusts the wire feeding and moving speed based on the conservation of volume and linear energy, and controls the heat source to shift towards the lower side of the misaligned edge, effectively avoiding the risks of burn-through of the thin plate of the cabinet and melt-collapse of the suspended edge. At the same time, by using high-frequency discrete accumulation of real-time heat input, it coordinates the execution of pressure reduction, speed increase and targeted physical cooling at the rear when approaching the deformation critical point, cutting off the longitudinal accumulation of thermal stress. In addition, relying on the rigid follow-up integrated hardware structure of front-viewing, middle welding and rear blowing, the mechanical delay of multi-axis linkage is eliminated, and the accurate implementation of adaptive seam finding and cooling algorithms is provided with a solid guarantee.

[0085] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An automatic welding method for sheet metal cabinets, characterized in that, Includes the following steps: S1: The main control computer plans the laser scanning data acquisition frame in advance based on the walking speed and direction of the multi-axis linear moving mechanism, and obtains the point cloud data in the data acquisition frame through the single-line laser contour sensor set in front of the arc welding gun. It calculates the actual gap width of the cabinet sheet metal joint and the height difference between the two sheet metal pieces. The main control computer obtains the current motion parameters of the moving actuator and the sampling period of the vision sensor. Based on the current motion parameters and the sampling period, it predicts the physical position range of the area to be welded at the next moment, and delineates the dynamic acquisition area based on the physical position range. Then, it controls the vision sensor to only extract and process the contour data inside the dynamic acquisition area, and shields the ambient light and splash interference outside the area. S2: The main control computer synchronously sends control commands to the digitally controlled welding machine and the multi-axis linear motion mechanism based on the change in the actual gap width. While increasing the wire feeding speed of the welding machine, the traveling speed of the multi-axis linear motion mechanism is increased proportionally. S3: The main control computer controls the arc welding gun to shift towards the lower sheet metal side according to the height difference, and controls the arc welding gun to increase the dwell time on the lower sheet metal side when swinging left and right. S4: The main control computer accumulates the total heat output to the sheet metal in real time throughout the welding process. When the total heat reaches the preset deformation critical point, it sends a voltage reduction command to the digitally controlled welding machine, increases the walking speed of the multi-axis linear movement mechanism, and activates the follow-up cooling nozzle located behind the arc welding gun for targeted cooling.

2. The automatic welding method for cabinet sheet metal according to claim 1, characterized in that, The specific process for calculating the actual gap width and misalignment difference of the sheet metal joint in S1 is as follows: The main control computer extracts the spatial height difference between adjacent data points within the dynamic acquisition area, removes abnormal interference points exhibiting abrupt changes by setting a height difference change threshold, then fits the remaining contour point cloud data to obtain flat line segments representing the two sheet metal surfaces, and extracts the discontinuous endpoints of the flat line segments as actual physical edges. The actual gap width is obtained by calculating the horizontal distance between the two actual physical edges, and the misalignment drop is obtained by calculating the vertical distance between the two flat line segments.

3. The automatic welding method for cabinet sheet metal according to claim 1, characterized in that, The specific process for increasing the wire feeding rate of the welding machine in S2 is as follows: In response to the detection that the actual gap width is increasing, the main control computer, based on the principle of volume conservation, combined with the widened gap size and the preset welding wire specifications, calculates the additional metal deposition amount required to fill the current incremental gap, and issues a corresponding speed-up command to the wire feeding actuator of the welding machine, outputting welding wire matching the additional metal deposition amount per unit time.

4. The automatic welding method for cabinet sheet metal according to claim 3, characterized in that, The specific process of collaboratively increasing the walking speed of the mobile actuator in S2 is as follows: The main control computer calculates the target moving speed required to maintain a constant heat input per unit length of sheet metal based on the additional arc heat input caused by the increase in wire feeding rate and the allowable thermal deformation threshold of the sheet metal material. It then synchronously drives the moving actuator to accelerate to the target moving speed, thereby offsetting the additional arc heat input by shortening the time the heat source acts on the unit path.

5. The automatic welding method for cabinet sheet metal according to claim 2, characterized in that, The specific process of controlling the energy center of the welding torch to shift laterally towards the lower-positioned sheet metal side in S3 is as follows: In response to the misalignment exceeding the set tolerance range, the main control computer calculates the lateral offset distance to avoid the high, overhanging edge, and drives the moving actuator to move the welding torch laterally by the lateral offset distance, so that the energy center of the welding torch deviates from the original seam center and is shifted and aligned with the bearing surface of the lower sheet metal.

6. The automatic welding method for cabinet sheet metal according to claim 5, characterized in that, The specific process of allocating a larger dwell time ratio to the lower-positioned sheet metal side in S3 is as follows: When the welding torch is driven to perform lateral oscillating welding, the main control computer performs asymmetrical time allocation of the oscillation cycle, so that the ratio of the dwell time of the welding torch on the sheet metal surface at a lower position is greater than the ratio of the sweeping time on the sheet metal edge at a higher position. This guides the heat source and molten pool to preferentially adhere to the bearing surface on the lower side, and relies on the heat attached by the sweeping action to achieve adhesion and fusion of the higher edge.

7. The automatic welding method for cabinet sheet metal according to claim 1, characterized in that, The specific process of calculating the cumulative heat input during the continuous integration welding process in S4 is as follows: The main control computer synchronously collects the real-time output current and real-time output voltage of the welding machine and the real-time walking speed of the moving actuator according to discrete time steps. By multiplying and integrating the real-time output current, the real-time output voltage and the real-time walking speed, the step input line energy corresponding to the time step is obtained. All the step input line energies from the welding start point to the current position are accumulated to obtain the cumulative heat input reflecting the current cumulative heating state of the sheet metal.

8. The automatic welding method for cabinet sheet metal according to claim 7, characterized in that, The specific process in S4 of lowering the output energy parameter of the welding machine and further increasing the walking speed of the moving actuator, while simultaneously activating the follow-up cooling device, is as follows: When the welding torch travels to the preset weld seam rear section and the cumulative heat input is detected to be approaching the deformation critical point, the main control computer, while maintaining the existing wire feeding amount unchanged, lowers the output voltage of the welding machine according to a preset gradient as a means of reducing the output energy parameter. At the same time, it issues an acceleration command to the moving actuator to move away from the high-temperature affected zone as soon as possible, and simultaneously activates the follow-up cooling device that moves with the welding torch to spray cooling medium in a directional manner onto the residual heat affected zone after welding.

9. An automatic welding device for cabinet sheet metal, characterized in that, The apparatus is used to perform the method according to any one of claims 1 to 8, specifically comprising: A moving unit (100) includes a base (101), on which transverse guide rails (102) are arranged parallel to each other on both sides. A longitudinal beam (103) is slidably mounted on the transverse guide rails (102), a Z-axis slider (104) is slidably mounted on the longitudinal beam (103), a load-bearing beam (105) is slidably mounted on the Z-axis slider (104), and a clamping device (106) is provided on the base (101). Welding unit (200), the welding unit (200) includes a connecting seat (201) provided on the bearing beam (105), a wire feeding motor (202) provided on the connecting seat (201), a wire feeding mechanism (203) connected to the bottom end of the wire feeding motor (202), a wire guide tube (204) connected to the output end of the wire feeding mechanism (203), and an arc welding gun (205) provided on one side of the wire guide tube (204); The auxiliary control unit (300) includes the wire guide tube (204) and the arc welding gun (205) with a fixed bracket (301) provided on it. One end of the fixed bracket (301) is connected to the suspension bracket (302), and a laser profile sensor (303) is provided on the suspension bracket (302). The other end of the fixed bracket (301) is provided with a cooling nozzle (304).

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