Automobile rear floor welding production line and method

Abstract

The present invention provides a production line and method for welding a rear floor panel of an automobile, which relates to the field of automobile welding lines. To address the current problem that the wheel cover position of a rear floor panel workpiece is affected by a reinforcement structure and is inconvenient to directly weld, a rounded rectangular workpiece conveying path is adopted. When the direction of the workpiece is adjusted during conveyance, the posture relative to the previous workstation also changes. The wheel cover position of the workpiece is welded using the welding mechanism of the previous workstation or the welding mechanism of the next workstation, and welding is performed from the bottom of the wheel cover upward. The molten pool and welding slag after welding are not easily attached to the workpiece under the action of gravity to cause defects, and the reinforcing structure on the workpiece can be avoided, thereby reducing interference with the workpiece structure and improving welding efficiency.

Description

Technical Field

[0001] The present invention relates to the field of automobile welding lines, and in particular to an automobile rear floor welding production line and method. Background Art

[0002] The rear floor panel of a vehicle, which houses components such as the wheel hub and drive shaft, requires high strength and rigidity. Stamping a single panel is difficult to achieve, so the rear floor panel is typically welded together from two panels: the center and the rear. To ensure this rigidity, a reinforcement structure is incorporated into the upper surface of the center panel to increase its effective cross-sectional area, thereby enhancing its bending stiffness under external loads. However, this also limits the welding position due to the reinforcement structures such as protrusions, stiffeners, and ribs on the upper surface.

[0003] Wheel covers are provided on both sides of the rear floor main body, and a reinforcement structure is also connected between the wheel covers and the rear floor main body. During the welding process, some welding positions and the reinforcement structure on the upper surface of the wheel covers are prone to interfere with the welding gun. Although the surface reinforcement structure can be avoided by adjusting the position of the weld points, the structural distribution of the reinforcement structure is also restricted. A Chinese patent (publication number: CN110039226B) discloses a vehicle rear floor assembly welding device. The device uses automatic equipment such as welding robots, special fixtures for station welding, and transfer transportation mechanisms to weld the panels to be welded in different stations, making the welding mode of the vehicle body welding floor into a linear mode to improve production efficiency. However, the device does not consider the problem of inconvenient operation of welding at the wheel cover position. Avoiding the reinforcement structure will lead to an increase in weld points and a longer welding process, affecting the production efficiency of the welding production line. During the welding process, there are also defects caused by molten pool flow and slag splashing. Summary of the Invention

[0004] The purpose of the present invention is to address the defects of the prior art and provide a production line and method for welding the rear floor of an automobile. The method adopts a rounded rectangular workpiece conveying path. When the direction of the workpiece is adjusted during conveying, the posture relative to the previous workstation also changes. The wheel cover position of the workpiece is welded using the welding mechanism of the previous workstation or the welding mechanism of the next workstation, and welding is performed from the bottom of the wheel cover upward. The molten pool and welding slag after welding are not easily attached to the workpiece under the action of gravity to cause defects, and can avoid the reinforcing structure on the workpiece, reduce interference with the workpiece structure, and improve welding efficiency.

[0005] The first object of the present invention is to provide a car rear floor welding production line, which adopts the following scheme:

[0006] include:

[0007] The conveying assembly includes a fixture running along a rounded rectangular track, the rounded rectangular track being divided into four straight paths along the running direction, and the fixture is provided with a clamping portion for carrying the workpiece;

[0008] The working device includes a material guiding station, a gluing station, a welding station and an inspection station corresponding to the four straight paths one by one. The welding station includes at least three welding mechanisms, wherein the first welding mechanism can act on the end of the workpiece at the gluing station, and the second welding mechanism can act on the end of the workpiece at the inspection station.

[0009] Furthermore, the first welding mechanism is located on the extension line of the straight path corresponding to the gluing station, and the first welding mechanism is configured to weld the wheel cover at the end of the workpiece on the gluing station from bottom to top.

[0010] Furthermore, the second welding mechanism is located on the extension line of the straight path corresponding to the detection station, and the second welding mechanism is configured to weld the wheel cover at the end of the workpiece on the detection station from bottom to top.

[0011] Furthermore, the material guiding station is provided with a material guiding component, the gluing station is provided with a gluing component, and the detection station is provided with a detection component.

[0012] Furthermore, adjacent straight line tracks are transitionally connected via arc tracks.

[0013] Furthermore, the clamp cyclically runs along a rounded rectangular track.

[0014] Furthermore, the conveying assembly also includes a drive chain, a guide rail and a track patrol trolley. The drive chain is a rounded rectangle that is closed at both ends. The guide rail is distributed outside the drive chain. The track patrol trolley moves along the guide rail. One side of the track patrol trolley is connected to the drive chain to obtain power, and the clamp is installed on the track patrol trolley.

[0015] Furthermore, the angular positions of the drive chain are respectively matched with sprockets, and at least one sprocket is a driving sprocket. When the driving sprocket is driven by the rotary drive member, it can drive the drive chain to rotate.

[0016] Furthermore, along the rotation direction of the drive chain, a plurality of track patrol trolleys are distributed in sequence at intervals.

[0017] Furthermore, the guide rail is in the shape of a rounded rectangle, and the arc end at the angular position of the guide rail and the arc end at the angular position of the drive chain are concentrically distributed.

[0018] A second object of the present invention is to provide a working method of the automobile rear floor welding production line as described in the first object, comprising:

[0019] The workpiece is loaded from the material guiding station to the fixture of the conveying assembly, and follows the fixture along the rounded rectangular track through the gluing station, welding station and inspection station in sequence;

[0020] Glue the workpiece at the gluing station, and weld the head end of the workpiece at the gluing station after gluing is completed;

[0021] Welding is performed on non-end positions of the workpiece at the welding station;

[0022] Before inspecting the workpiece at the inspection station, weld the end of the workpiece at the inspection station, and inspect after welding is completed;

[0023] The workpieces that pass the inspection are unloaded at the material guiding station, and the workpieces that fail the inspection are repaired again at the gluing station, welding station and inspection station until they pass the inspection and are unloaded.

[0024] Furthermore, the head end of the workpiece is welded at the end of the linear path corresponding to the gluing station.

[0025] Furthermore, when welding the workpiece on the gluing station, the welding gun of the first welding mechanism is inserted into the wheel cover at the end of the workpiece to weld from bottom to top.

[0026] Furthermore, the end of the workpiece is welded at the beginning of the linear path corresponding to the inspection station.

[0027] Furthermore, when welding the workpiece on the inspection station, the welding gun of the second welding mechanism is inserted into the wheel cover at the end of the workpiece to weld from bottom to top.

[0028] Compared with the prior art, the present invention has the following advantages and positive effects:

[0029] (1) In order to solve the problem that the wheel cover position of the rear bottom plate workpiece is affected by the reinforcement structure and is inconvenient to be directly welded, a rounded rectangular workpiece conveying path is adopted. When the direction of the workpiece is adjusted during the conveying process, the posture relative to the previous station also changes. The wheel cover position of the workpiece is welded using the welding mechanism of the previous station or the welding mechanism of the next station, and welding is performed from the bottom of the wheel cover to the top. The molten pool and welding slag after welding are not easy to adhere to the workpiece under the action of gravity to cause defects, and can avoid the reinforcement structure on the workpiece, reduce interference with the workpiece structure, and improve welding efficiency.

[0030] (2) The use of a rounded rectangular running track can realize the rotary cycle operation of the fixture. When the inspection station identifies defects in the workpiece processing, there is no need to unload the material and then repair it through the material guiding station, gluing station and welding station. This reduces the long-distance transportation process during the repair process in the welding production line and improves the welding efficiency and repair efficiency.

[0031] (3) Compared with adjusting the workpiece posture by flipping, a drive chain is used to drive the fixture to move cyclically along a rounded rectangular trajectory. The change in the workpiece posture at the turning position is used to configure the welding mechanism to a position suitable for welding. During the transportation process, the workpiece always remains on the fixture and is on a straight path, which is convenient for confirming the workpiece position and precise welding.

[0032] (4) The use of a drive chain can facilitate the formation of the required rounded rectangular path, and the rounded rectangular guide rail is used to guide the patrol trolley carrying the fixture to ensure the accuracy of the workpiece during operation, thereby matching the distribution positions of the gluing components, material guiding components, detection components and welding mechanisms, making it easier to determine the relative positions of the corresponding robot end and the workpiece of each component and reducing interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1 This is an axonometric diagram of the automobile rear floor welding production line in Examples 1 and 2 of the present invention.

[0035] Figure 2 This is a production flow chart of the automobile rear floor welding production line in Examples 1 and 2 of the present invention.

[0036] Figure 3 This is an axonometric view of the material guide assembly in Examples 1 and 2 of the present invention.

[0037] Figure 4 Schematic diagram of the conveying assembly in Examples 1 and 2 of the present invention.

[0038] Figure 5 This is an axonometric view of the track patrol vehicle in Examples 1 and 2 of the present invention.

[0039] Figure 6 Schematic diagram of the exploded structure of the track patrol vehicle in Examples 1 and 2 of the present invention.

[0040] Figure 7 Schematic diagram of the connection between the track patrol trolley and the clamp in Examples 1 and 2 of the present invention.

[0041] Figure 8 This is an axonometric view of the gluing mechanism in Examples 1 and 2 of the present invention.

[0042] Figure 9 Schematic diagram of the gluing mechanism in Examples 1 and 2 of the present invention.

[0043] Figure 10 Schematic diagram of the SPR cold connection technology welding gun in Examples 1 and 2 of the present invention.

[0044] Figure 11 This is a cross-sectional view of the SPR cold connection technology welding gun in Examples 1 and 2 of the present invention.

[0045] Figure 12 Schematic diagram of the SPR cold connection technology welding process in Examples 1 and 2 of the present invention.

[0046] Figure 13 Schematic diagram of the CMT cold metal transfer welding equipment in Examples 1 and 2 of the present invention.

[0047] Figure 14 Schematic diagram of the CMT cold metal transfer welding process in Examples 1 and 2 of the present invention.

[0048] Figure 15 This is an axonometric view of the automobile rear floor workpiece in Examples 1 and 2 of the present invention.

[0049] Among them, I. material guiding component, II. conveying component, III. gluing component, IV. welding component, V. detection component.

[0050] I-1. Gantry truss, I-2. Vacuum adsorption mechanism.

[0051] II-1. Driving sprocket, II-2. Track patrol trolley, II-3. Guide rail, II-4. Support plate, II-5. Driven sprocket, II-6. Drive chain, II-2-1. Mounting nut, II-2-2. Gasket, II-2-3. Screw, II-2-4. Car body, II-2-5. Connecting hole, II-2-6. Rivet positioning slot, II-2-7. Wheel, II-2-8. Mounting hole.

[0052] III-1. Gluing robot, III-2. Glue gun, III-3. Vision sensor for detecting the model of the rear floor panel of the car, III-4. Vision sensor for the gluing path, III-5. Vision sensor for detecting the gluing quality.

[0053] IV-1. Welding gun, IV-1-1. Punch, IV-1-2. Rivet, IV-1-3. Upper material, IV-1-4. Lower material, IV-1-5. Mold, IV-1-6. Hollow structure, IV-2. CMT cold metal transfer welding system, IV-2-1. CMT cold metal transfer welding gun, IV-2-2. Cold metal transfer power supply, IV-2-3. Wire feed control system, IV-2-4. Robot control system, IV-2-5. Editor, IV-3. Fixture, IV-3-1. Workpiece, IV-3-2. Rivet mounting slot, IV-3-3. Rivet. DETAILED DESCRIPTION

[0054] Example 1

[0055] In a typical embodiment of the present invention, Figures 1-15 As shown, a car rear floor welding production line is provided.

[0056] At present, most rear floor welding production lines use a one-way conveying method for processing, and conduct inspections after welding is completed. If the inspection shows unqualified results, the workpiece needs to be transported to the upstream of the welding production line, re-clamped and loaded for repair, resulting in low processing efficiency. In addition, for the wheel arch position of the rear floor, due to the presence of many reinforcing structures, when the welding point position is close to the reinforcing structure, interference between the reinforcing structure and the welding gun IV-1 is likely to occur, making the welding work difficult to perform. Adjusting the welding point position may increase the welding process, increase the process flow, and affect production efficiency. Based on this, the present embodiment provides a rear floor welding production line for automobiles, which uses a fixture that runs on a rounded rectangular track. The fixture carries the workpiece and transports it along a rounded rectangular track, passing through the material guiding station, gluing station, welding station and inspection station in sequence. When unqualified workpieces appear, they can be repaired at each station without unloading and reloading, thereby improving production efficiency.

[0057] In addition, a rounded rectangular workpiece conveying path is used. When the direction is adjusted during the workpiece conveying process, the posture relative to the previous workstation also changes. The wheel cover position of the workpiece is welded using the welding mechanism of the previous workstation or the welding mechanism of the next workstation, and welding is performed from the bottom of the wheel cover upward. The molten pool and welding slag after welding are not easy to adhere to the workpiece under the action of gravity to cause defects, and can avoid the reinforcing structure on the workpiece, reduce interference with the workpiece structure, and improve welding efficiency.

[0058] See also Figure 1 The automotive rear floor panel welding production line primarily consists of a conveyor assembly II, a material guide assembly I, a gluing assembly III, a welding assembly IV, and an inspection assembly V. These three components function as working devices, enabling the loading, unloading, and welding of workpieces. Conveyor assembly II is equipped with a fixture that moves along a rounded rectangular track, driving the workpiece-carrying clamping portion onto which it is placed.

[0059] like Figure 2 As shown, workpieces are loaded from the material guiding station into the fixture of the conveyor assembly II. Gluing is performed at the gluing station, welding is performed on non-end parts at the welding station, and inspection is performed at the inspection station. Workpieces that pass inspection are unloaded at the material guiding station. Workpieces that fail inspection are repaired again at the gluing, welding, and inspection stations until they pass inspection and are unloaded.

[0060] The rounded rectangular track of the fixture is divided into four segments, each of which is a straight line path, forming four straight line paths, such as Figure 4 As shown, an arc track is provided between adjacent straight paths for transition, and adjacent straight paths are connected by the arc track transition, so that the fixture can smoothly move from one straight path to another straight path via the arc track.

[0061] The four workstations, namely the material guiding station, the gluing station, the welding station and the inspection station, correspond one to one with the four straight paths. A material guiding component I is arranged at the material guiding station, a gluing component III is provided at the gluing station, an inspection component V is provided at the inspection station, and a welding component IV is provided at the welding station. The welding component IV includes at least three welding mechanisms, among which the first welding mechanism can act on the end of the workpiece at the gluing station, the second welding mechanism can act on the end of the workpiece at the inspection station, and weld the workpiece from the outside of the end of the workpiece; the other welding mechanisms can weld the welding points at non-end positions of the workpiece.

[0062] The first welding mechanism is located on the extension line of the straight path corresponding to the gluing station, and the first welding mechanism is configured to weld the wheel cover at the end of the workpiece on the gluing station from bottom to top; Figure 4 Taking the posture shown as an example, the first welding mechanism is located on the left side of the gluing station and in the same column as the welding station; the second welding mechanism is located on the extension line of the straight path corresponding to the inspection station, and the second welding mechanism is set to weld the wheel cover at the end of the workpiece on the inspection station from bottom to top; Figure 4 Taking the posture shown as an example, the second welding mechanism is located on the left side of the inspection station and in the same column as the welding station.

[0063] The fixture circulates along a rounded rectangular path, causing the workpiece on the fixture's carrier to follow this path. This changes the relative position of the workpiece and the various components of the working device, allowing for the proper operation of different components. The placement of the first and second welding mechanisms does not affect the movement of the workpiece on the conveyor assembly II. The workpiece can be welded by adjusting the position of the welding torch IV-1, while avoiding interference with the workpiece during transport.

[0064] like Figure 15 As shown, the wheel covers are located at both ends of the rear bottom plate body. The wheel covers are plate structures with a convex top surface and a concave bottom surface. In order to improve the connection strength between the wheel cover and the rear bottom plate body, a reinforcement structure is also connected between the wheel cover and the rear bottom plate body, and the welding points are distributed on the wheel cover and the rear bottom plate body. Some welding positions and the reinforcement structure on the upper surface of the wheel cover are easy to interfere with the welding gun IV-1. If the workpiece is adjusted to flip the workpiece for welding, although the reinforcement structure on the upper surface is avoided, repositioning is required after the flipping process and when returning to the posture after welding, which increases the operation process. Repeated clamping will also lead to low processing efficiency. In this regard, compared with adjusting the workpiece posture by flipping, in this embodiment, a drive chain is used to drive the clamp to move cyclically along a rounded rectangular trajectory. The change in the workpiece posture at the turning position is used to configure the welding mechanism to a position suitable for welding. During the transportation process, the workpiece always remains on the clamp and is on a straight path, which is convenient for confirming the workpiece position and precise welding.

[0065] In addition, it should be pointed out that in this embodiment, the working posture of the welding gun IV-1 for wheel cover welding is also adjusted, and welding is performed from the bottom of the wheel cover upward. The molten pool and welding slag after welding are not easy to adhere to the workpiece under the action of gravity to cause defects, and can avoid the reinforcing structure on the workpiece, reduce interference with the workpiece structure, and improve welding efficiency.

[0066] like Figure 3 As shown, the material guide assembly I includes a gantry truss I-1 and a vacuum adsorption mechanism I-2. The gantry truss I-1 is a three-axis motion mechanism. The vacuum adsorption mechanism I-2 is installed at the end of the gantry truss I-1, so that the gantry truss I-1 drives the vacuum adsorption mechanism I-2 to adjust. The vacuum adsorption mechanism I-2 can grab the workpiece for loading and unloading, load the workpiece to the bearing part of the fixture, and unload the workpiece on the bearing part to the workpiece stacking area.

[0067] like Figure 4 As shown, escort assembly II also includes a drive chain II-6, a guide rail II-3, and a patrol trolley II-2. The drive chain II-6 is a closed, rounded rectangle with end-to-end connections. The guide rail II-3 is located outside the drive chain. The patrol trolley II-2 moves along the guide rail II-3. One side of the patrol trolley II-2 is connected to the drive chain II-6 for power, and a clamp is mounted on the patrol trolley II-2. Sprockets are attached to the angular positions of the drive chain II-6, at least one of which is a driving sprocket II-1. When the driving sprocket II-1 is driven by the rotary drive element, it can drive the drive chain II-6 and the other driven sprockets II-5 to rotate.

[0068] Along the rotation direction of the drive chain II-6, multiple track patrol trolleys II-2 are distributed in sequence, and the guide rail II-3 is a rounded rectangle. The arc ends of the guide rail II-3 and the arc ends of the drive chain II-6 are concentrically distributed.

[0069] Specifically, such as Figure 4 As shown, this embodiment features a driving sprocket II-1 and three driven sprockets II-5, located at the four corners of a rounded rectangle. A transmission motor is used as the rotary drive element, which drives the driving sprocket II-1. A drive chain II-6 connects the driving sprocket II-1 and the three driven sprockets II-5 in series. The track-patrolling trolley II-2 is provided with connecting holes II-2-5 and is mounted to the drive chain II-6 via screws II-2-3, enabling movement along the guide rail II-3. A support plate II-4 is provided between the two sprockets to tension the drive chain II-6 and prevent it from drooping in the middle due to excessive length.

[0070] like Figure 5-Figure 7As shown, the track patrol trolley II-2 consists of a mounting nut II-2-1, a washer II-2-2, a screw II-2-3, a body II-2-4, a connection hole II-2-5, a rivet positioning slot II-2-6, a wheel II-2-7, and a mounting hole II-2-8. Specifically, the body II-2-4 is provided with mounting hole II-2-8 and connection hole II-2-5 for installing the rivet positioning slot II-2-6 and connecting to the drive chain II-6, respectively. The rivet positioning slot II-2-6 is externally threaded and secured within the mounting hole II-2-8 via a washer II-2-2 and a mounting nut II-2-1. The washer II-2-2 serves to disperse the tightening pressure and prevent damage to the body II-2-4. The bottom of the fixture features a rivet mounting slot IV-3-2 for mounting rivet IV-3-3. This rivet IV-3-3 mates with the rivet positioning slot II-2-6 on the track-track trolley II-2, allowing the fixture to be mounted on the track-track trolley II-2, allowing the fixture and its loaded workpiece to follow the movement of the track-track trolley II-2. This helps position the workpiece during transport. As the fixture is transported along a rounded rectangular track, this reduces workpiece deviation caused by shaking during changes in transport direction, thereby improving positioning accuracy.

[0071] like Figure 8-Figure 9 As shown, in this embodiment, the gluing assembly IIIIII consists of a gluing robot III-1, a glue gun III-2, a visual sensor III-3 for detecting the model of the rear floor panel, a visual sensor III-4 for detecting the gluing path, and a visual sensor III-5 for detecting the gluing quality. These sensors are simultaneously fixed to the glue gun III-2 and move with it. The visual sensor III-3 for detecting the model of the rear floor panel is located on the upper front side of the glue gun III-2, the visual sensor III-4 for detecting the gluing path is located to the right of the glue gun III-2, and the visual sensor III-5 for detecting the gluing quality is located to the left of the glue gun III-2.

[0072] Specifically, before gluing, the gluing robot III-1 adjusts its field of view to the gluing area and identifies the vehicle's rear underbody. The rear underbody model detection visual sensor III-3 enables the robot to proactively invoke a supporting program to ensure accurate gluing. During gluing, the gluing path visual sensor III-4 follows the glue gun III-2, prioritizing spatial recognition and providing it to the control system to control the glue gun III-2's path planning. The glue quality detection visual sensor III-5 captures real-time images of the glue application for subsequent processing and analysis. The visual sensor interfaces with the MES control system, using image processing methods to inspect and analyze captured images of the glue strips to ensure gluing quality and continuity.

[0073] like Figure 10-12 As shown, the welding assembly IV in this embodiment includes multiple welding mechanisms, and the welding mechanism is composed of a multi-station welding robot IV, an SPR cold connection system, and a CMT cold metal transfer welding system IV-2.

[0074] Specifically, SPR cold connection technology is as follows Figure 10-12 As shown, taking the welding of the upper material IV-1-3 and the lower material IV-1-4 on the workpiece as an example, under the pressure of the welding gun IV-1 of the SPR cold connection technology, the welding punch IV-1-1 causes the rivet IV-1-2 to penetrate the upper material IV-1-3. Under the action of the mold IV-1-5, the hollow structure IV-1-6 of the rivet leg flows and extends into the lower material IV-1-4 and penetrates the lower material IV-1-4, but does not pierce the lower material IV-1-4, forming a mutually embedded and plastically deformed rivet connection. The specific welding process includes:

[0075] 1. The welding punch IV-1-1 moves downward, pushing the rivet IV-1-2 and forcing it to pierce the upper layer material IV-1-3. At the same time, the rivet also drives the lower layer material IV-1-4 to plastically deform and enter the die IV-1-5.

[0076] 2. Expansion Phase: As the welding process progresses, the hollow structure IV-1-6 of the leg of rivet IV-1-2 gradually expands, and the underlying material IV-1-4 undergoes plastic deformation and gradually fills the mold IV-1-5. Under the combined action of the punch and boss, the hollow structure IV-1-6 of the leg of rivet IV-1-2 expands and embeds into the underlying material IV-1-4, forming a mechanical interlocking structure between rivet IV-1-2 and the sheet.

[0077] 3. Punch and riveting completed: Welding is complete when the welding punch IV-1-1 continues to press down on the rivet IV-1-2 until the rivet head of the rivet IV-1-2 is in close contact with and flush with the upper surface of the first layer of material IV-1-3. The blank holder releases its holding force, and the welding punch IV-1-1 returns to its initial position, completing the welding process.

[0078] CMT cold metal transfer welding Figure 13 As shown, the basic principle of cold metal is short-circuit transfer welding technology. When the cold metal transfer welding technology uses the short-circuit contact between the molten droplet and the molten pool, the welding wire not only has the movement of feeding forward, but also has the movement of retracting.

[0079] The CMT cold metal transfer welding process utilizes the CMT Cold Metal Transfer Welding System IV-2, which features welding parameter monitoring and artificial intelligence management. The CMT cold metal transfer welding torch IV-2-1 is connected to a digital wire feed control system IV-2-3. This control system, by controlling the cold metal transfer power supply IV-2-2, controls the advance and retraction of the welding wire, thereby ensuring a perfect physical integration of the wire feed and droplet transfer processes, further stabilizing the arc. The mechanical conversion frequency facilitates high-speed wire feed and retraction. The robotic welding control system IV-2-4 utilizes a KUKA KR50 robot, offering high static and dynamic accuracy, crucial for ensuring arc stability during welding. The editor IV-2-5 is used to collect welding process parameters.

[0080] like Figure 14 As shown in the figure, the CMT cold metal transfer welding process is divided into four parts: arc ignition, droplet formation; droplet contact with the molten pool, arc extinguishing, current reduction; current short circuit, wire retraction, droplet shedding, short circuit current maintained at a minimum value; wire movement direction changes, arc re-ignition, and the start of the next droplet transfer process. Specifically including:

[0081] 1. The arc burns and the welding wire is fed forward until a molten droplet short circuit is formed.

[0082] 2. When the digital wire feeding control system IV-2-3 detects a short circuit signal, it will be fed back to the front-end wire feeding mechanism through the editor IV-2-5.

[0083] 3. The CMT Cold Metal Transfer welding system IV-2 responds by retracting. The wire feed speed is reversed and the wire is retracted. At this time, the current and voltage are almost zero.

[0084] 4. When the molten droplet falls off the end of the welding wire, the arc is reignited, the welding wire is fed forward again, and the molten droplet transfer begins again.

[0085] In addition to the aforementioned forces, during cold metal transfer welding, the force of droplet transfer is also generated by the sudden termination of forward wire feeding and the reverse wire retraction at a certain speed when the droplet is about to transfer. This generates a reverse force, which in turn generates a reverse impulse to maintain inertia for the droplet about to transfer. The magnitude of the reverse impulse depends on the wire feeding speed, the instantaneous reverse wire retraction speed, and the time required to reach the reverse wire retraction speed, which conforms to the law requirements of formula (1):

[0086] F Δt =mv1-mv2 (1)

[0087] Where v1 and v2 are the wire rewind and wire feeding speeds (mm / s), respectively; m is the mass of the droplet at the moment of droplet transfer (g); and Δt is the wire feeding speed and the time to reach the set wire rewind speed during a certain cycle (s).

[0088] Automotive body parts have complex shapes, mostly three-dimensional curved surfaces. These thin plates are relatively large and have low strength and rigidity. For thin or easily deformed workpieces, the fixture uses two locating pins and a locating surface to control the six degrees of freedom of the workpiece to be welded. Multi-point clamping ensures rigidity and reduces the possibility of deformation during welding. The workpiece to be welded has pre-set holes, and the fixture has locating pins. These pins mate with the pre-set locating holes on the workpiece to provide primary positioning. Three support pins define a support surface, providing auxiliary positioning support for the workpiece.

[0089] In this embodiment, the visual component consists of an industrial camera, a lighting system, an image acquisition card, an industrial computer and a control system.

[0090] After welding is complete, the workpiece is transported by Conveyor Component II to the Vision Component. Specifically, an industrial camera captures the weld seam. The image acquisition card uses image processing to save the captured weld seam photos to an industrial computer for inspection and analysis. The control system interfaces with the MES control system, and the results are uploaded to the data service center to establish real-time quality warnings and automatically prevent errors. If the visual inspection results are satisfactory, Conveyor Component II transports the workpiece to the loading and unloading device for unloading. If the inspection results are unsatisfactory, Conveyor Component II transports the workpiece to the gluing and welding stations for repairs.

[0091] In this embodiment, the data acquisition and transmission system for the automotive rear floor welding production line is based on an RS485 bus and Ethernet signal acquisition system, interconnected with the MES control system to achieve real-time data collection and upload to the MES's central control management system. Specifically, this includes: uploading workpiece barcode markings before loading; receiving workpiece model data uploaded by the visual sensor during the gluing process; the MES master control system analyzing the corresponding workpiece model based on the workpiece model data and invoking the corresponding gluing program and welding process parameters; receiving welding parameters uploaded by the editor during the welding process; real-time monitoring of changes in welding current, voltage, and other parameters; and receiving welding quality data generated by the visual inspection system. This data is then uploaded to the data service center for subsequent product traceability. This enables the collection and integrated utilization of workpiece loading, key welding process, and finished product inspection data during the automotive rear floor welding process.

[0092] Example 2

[0093] In another typical embodiment of the present invention, Figures 1-15 As shown, a working method utilizing an automobile rear floor welding production line is provided.

[0094] The automobile rear floor welding production line in Example 1 includes the following steps:

[0095] The workpiece is loaded from the material guiding station to the fixture of the escort component II, and follows the fixture along the rounded rectangular track through the gluing station, welding station and inspection station in sequence;

[0096] Glue the workpiece at the gluing station, and weld the head end of the workpiece at the gluing station after gluing is completed;

[0097] Welding is performed on non-end positions of the workpiece at the welding station;

[0098] Before inspecting the workpiece at the inspection station, weld the end of the workpiece at the inspection station, and inspect after welding is completed;

[0099] The workpieces that pass the inspection are unloaded at the material guiding station, and the workpieces that fail the inspection are repaired again at the gluing station, welding station and inspection station until they pass the inspection and are unloaded.

[0100] The head end of the workpiece is welded at the end of the straight path corresponding to the gluing station, and the end end of the workpiece is welded at the head end of the straight path corresponding to the inspection station.

[0101] When welding the workpiece at the gluing station, the welding gun IV-1 of the first welding mechanism penetrates into the wheel cover at the end of the workpiece and welds from bottom to top. When welding the workpiece at the inspection station, the welding gun IV-1 of the second welding mechanism penetrates into the wheel cover at the end of the workpiece and welds from bottom to top.

[0102] A rounded rectangular workpiece conveying path is adopted. When the direction of the workpiece is adjusted during conveyance, the posture relative to the previous workstation also changes. The wheel cover position of the workpiece is welded using the welding mechanism of the previous workstation or the welding mechanism of the next workstation, and welding is performed from the bottom of the wheel cover upward. The molten pool and welding slag after welding are not easy to adhere to the workpiece under the action of gravity to cause defects, and can avoid the reinforcing structure on the workpiece, reduce interference with the workpiece structure, and improve welding efficiency.

[0103] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A working method of an automobile rear floor welding production line, characterized in that: The automobile rear floor welding production line used includes: The conveying assembly includes a fixture running along a rounded rectangular track, the rounded rectangular track being divided into four straight paths along the running direction, and the fixture is provided with a clamping portion for carrying the workpiece; The working device includes a material guiding station, a gluing station, a welding station, and an inspection station corresponding to the four linear paths. The welding station includes at least three welding mechanisms, wherein the first welding mechanism can act on the end of the workpiece in the gluing station, and the second welding mechanism can act on the end of the workpiece in the inspection station. The material guiding station is provided with a material guiding component, the gluing station is provided with a gluing component, and the detection station is provided with a detection component; Adjacent straight tracks are connected by arc tracks; the fixture circulates along the rounded rectangular track; the welding mechanism is configured to a position suitable for welding by utilizing the change in the posture of the workpiece at the turning position, and the wheel cover position of the workpiece is welded by the welding mechanism of the previous station or the welding mechanism of the next station; The automobile rear floor welding production line also includes a data acquisition and transmission system, which is connected to the MES control system. The MES master control system analyzes the corresponding workpiece model based on the workpiece model data and calls the corresponding gluing program and welding process parameters; The first welding mechanism is located on the extension line of the straight path corresponding to the gluing station, and is configured to weld the wheel cover at the end of the workpiece at the gluing station from bottom to top; the second welding mechanism is located on the extension line of the straight path corresponding to the inspection station, and is configured to weld the wheel cover at the end of the workpiece at the inspection station from bottom to top; Working methods include: The workpiece is loaded from the material guiding station to the fixture of the conveying assembly, and follows the fixture along the rounded rectangular track through the gluing station, welding station and inspection station in sequence; Glue the workpiece at the gluing station, and weld the head end of the workpiece at the gluing station after gluing is completed; Welding is performed on non-end positions of the workpiece at the welding station; Before inspecting the workpiece at the inspection station, weld the end of the workpiece at the inspection station, and inspect after welding is completed; The workpieces that pass the inspection are unloaded at the material guiding station, and the workpieces that fail the inspection are repaired again at the gluing station, welding station and inspection station until they pass the inspection and are unloaded; The head end of the workpiece is welded at the end of the straight path corresponding to the gluing station; the end of the workpiece is welded at the head end of the straight path corresponding to the inspection station.

2. The working method of the automobile rear floor welding production line according to claim 1, characterized in that: The conveying assembly also includes a drive chain, a guide rail and a track patrol trolley. The drive chain is a closed rounded rectangle connected end to end. The guide rail is distributed outside the drive chain. The track patrol trolley moves along the guide rail. One side of the track patrol trolley is connected to the drive chain to obtain power, and the clamp is installed on the track patrol trolley.

3. The working method of the automobile rear floor welding production line according to claim 2, characterized in that: The angular positions of the drive chain are respectively matched with sprockets, and at least one sprocket is a driving sprocket. When the driving sprocket is driven by the rotary drive member, it can drive the drive chain to rotate.

4. The working method of the automobile rear floor welding production line according to claim 3, characterized in that: Along the rotation direction of the drive chain, multiple track patrol trolleys are distributed in sequence at intervals.

5. The working method of the automobile rear floor welding production line according to claim 2, characterized in that: The guide rail is in the shape of a rounded rectangle, and the arc end at the angular position of the guide rail and the arc end at the angular position of the drive chain are concentrically distributed.

6. The working method of the automobile rear floor welding production line according to claim 1, characterized in that: When welding the workpiece on the gluing station, the welding gun of the first welding mechanism is inserted into the wheel cover at the end of the workpiece to weld from bottom to top.

7. The working method of the automobile rear floor welding production line according to claim 1, characterized in that: When welding the workpiece on the inspection station, the welding gun of the second welding mechanism is inserted into the wheel cover at the end of the workpiece to weld from bottom to top.

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