Industrial robot rolling forming process and equipment for variable cross-section parts

Abstract

According to the embodiment of the invention, the industrial robot technology is applied to the rolling forming process of the variable cross-section part, and the rolling path can be dynamically adjusted according to the variable cross-section characteristics of the part, so that efficient machining is realized. According to the technology, the limitation of an existing technology in complex geometrical shape machining is broken through and solved, and an industrial robot can conduct high-quality and high-precision rolling forming on the variable cross-section part of a complex structure under the condition that the industrial robot does not depend on a mold. In addition, by combining the flexible path control capability of a robot, the forming precision of the variable cross-section part is remarkably improved, and compared with a raw material, the mechanical property loss of a bending area material of the part obtained after forming through the technology is smaller than 30%.

Description

Technical Field

[0001] This invention relates to the field of flexible manufacturing technology for industrial robots, and in particular to a roll forming process and equipment for industrial robots for variable cross-section parts. Background Technology

[0002] Industrial robot roll forming technology is a novel progressive forming method for sheet metal that has been widely used in the manufacturing of lightweight structural components for aerospace, rail transportation, and automobiles in recent years. This technology typically utilizes the roller tool head equipped with an industrial robot to apply multiple passes of progressive loading to metal sheets, thereby achieving continuous bending forming of parts with complex cross-sections.

[0003] Currently, industrial robot roll forming technology is mainly used in the manufacturing of metal parts with fixed cross-sections, such as structural components with straight edges and constant widths. The geometry of these parts remains unchanged along the processing direction, making them suitable for processing using a fixed trajectory and constant rolling pressure. However, as engineering structures develop towards high integration, lightweighting, and functional integration, more and more parts exhibit variable cross-section characteristics, such as structures with gradually changing height, width, or curvature along their length. During the forming process of these parts, the sheet metal experiences complex local stresses and uneven deformation. If the traditional fixed-track roll forming method is still used, it can easily lead to insufficient forming accuracy, severe springback, or even instability and cracking.

[0004] Therefore, it is necessary to develop an industrial robot roll forming process suitable for thin-walled parts with variable cross-sections in order to improve forming quality and expand the applicability of roll forming technology. Summary of the Invention

[0005] In view of the above problems, an industrial robot roll forming process and equipment for variable cross-section parts is proposed to overcome or at least partially solve the above problems, specifically including: An industrial robot roll forming process for variable cross-section parts includes: Construct a 3D model of the target variable cross-section part, and extract the spatial path features of the target variable cross-section part based on the 3D model; Based on spatial path characteristics, a functional relationship is constructed between the motion trajectory of the forming roller and its attitude as the position of the forming roller changes; The functional relationship is input into RoboDK simulation software to generate simulation results of the motion trajectory and attitude of the forming roller as the position of the forming roller changes, and the simulation results are verified. Based on the verified simulation results, a robot motion program is generated; The original flat sheet is fixed in the fixture, and the robot is controlled to roll the original flat sheet according to the robot motion program. The original flat sheet material is a metal sheet material with a thickness ranging from 1mm to 4mm.

[0006] Optionally, securing the original flat sheet material to the fixture includes: Clamp the original flat sheet into the fixture, and align the bottom edge of the original flat sheet with the bottom edge of the fixture; Adjust the position of the original flat plate material horizontally in the fixture until the starting point of the original flat plate material and the fixture reference line are on the same straight line, and fix the original flat plate material. The fixture reference line is located at the side edge of the fixture and is perpendicular to the bottom edge of the fixture.

[0007] Optionally, before controlling the robot to roll the original flat sheet material according to the robot motion program, the following steps are included: A global coordinate system is established with the starting point of the original flat sheet material as the origin, the line passing through the origin and parallel to the bottom edge of the fixture as the x-axis, and the line passing through the origin and parallel to the side edge of the fixture as the z-axis. Calibrate the coordinate positions of the forming roller and the support roller; Simultaneously adjust the positions of the forming roller and the support roller until the starting point of the forming roller's movement trajectory coincides with the starting point of the original flat plate on the fixture; Load the robot motion program into the robot controller and drive the forming roller to run along the forming roller's motion trajectory without moving. Check whether the forming roller's empty running trajectory is consistent with the motion trajectory. If they are not consistent, adjust the forming roller's pose until the forming roller's empty running trajectory is consistent with the motion trajectory.

[0008] Optionally, the robot is controlled to roll the original flat sheet material, including: The rolling process is divided into several passes, and the forming rollers located on the robot are controlled to perform the first pass of rolling on the original flat sheet material along the roller movement trajectory in the first posture. Adjust the posture of the forming roller and control the forming roller to roll the sheet material along the roller movement trajectory in the Nth posture until all rolling passes are completed.

[0009] Optionally, path continuity can be maintained between different stages.

[0010] Optionally, the forming speed can be set to 25 mm / s.

[0011] Optionally, when machining multiple types of variable cross-section parts, the process may also include: Establish a 3D model of each type of variable cross-section part, and extract the spatial path features of each type of variable cross-section part based on the 3D model; Based on the characteristics of each spatial path, a functional relationship is constructed between the motion trajectories of multiple forming rollers and their attitudes as the position of the forming rollers changes. Multiple functional relationships are input into RoboDK simulation software to generate simulation results of the motion trajectories of multiple forming rollers and the changes in their attitudes as the position of the forming rollers changes, and the simulation results are verified. Based on the verified simulation results, robot motion programs corresponding to each type of variable cross-section part are generated. Save the robot motion program as a file corresponding to each type of variable cross-section part, and unify the file name to a format that the system can recognize the part type; The original flat sheet is fixed in the fixture. The required processing model is selected in the system HMI interface. The system automatically loads the corresponding robot motion program and controls the robot to roll the original flat sheet according to the robot motion program.

[0012] The present invention also provides an industrial robot roll forming equipment for variable cross-section parts, comprising: Clamps are used to hold the original flat sheet material in place; The robot is located on both sides of the original flat sheet and is equipped with forming rollers and supporting rollers; the forming rollers act on the outer surface of the original flat sheet and the supporting rollers act on the inner surface of the original flat sheet.

[0013] Optionally, the support rollers and the forming rollers move synchronously.

[0014] Optionally, the support rollers are also used to act as molds and / or fixtures during the forming process.

[0015] This invention applies industrial robot technology to the roll forming process of variable cross-section parts, enabling dynamic adjustment of the roll forming path based on the variable cross-section characteristics of the part, thereby achieving efficient processing. This technological breakthrough overcomes the limitations of existing processes in processing complex geometries, allowing industrial robots to perform high-quality, high-precision roll forming of complex variable cross-section parts without relying on molds. Furthermore, by combining the robot's flexible path control capabilities, this invention significantly improves the forming accuracy of variable cross-section parts, and the mechanical property loss in the bending area of ​​the part formed by this process is less than 30% compared to the raw material. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the accompanying 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.

[0017] Figure 1 This is a schematic diagram of the industrial robot roll forming device used in an embodiment of the present invention; Figure 2 A schematic diagram of the structural parameters of the target part; Figure 3 This is a schematic diagram of path trajectory planning provided in an embodiment of the present invention; Figure 4 This is a contour drawing of the part after roll forming provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of trajectory jump caused by path splicing failure provided as a comparative example of the present invention. Figure 6 A schematic diagram of the morphology of an actual failed forming part provided as a comparative example of the present invention; Figure 7 This is a schematic diagram illustrating path reuse and rapid switching for robot processing of multiple types of variable cross-section parts, provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] This invention provides an industrial robot roll forming process for variable cross-section parts, which may specifically include the following steps: A 3D model of the target variable cross-section part is constructed, and its spatial path features are extracted from the 3D model. Based on the spatial path features, a functional relationship is constructed between the motion trajectory and attitude of the forming roller and the change in the position of the forming roller. The functional relationship is input into RoboDK simulation software to generate simulation results of the motion trajectory and attitude of the forming roller and the change in the position of the forming roller, and the simulation results are verified. Based on the verified simulation results, a robot motion program is generated. The original flat sheet is fixed to the fixture, and the robot is controlled to roll the original flat sheet according to the robot motion program. The original flat sheet can be DP590 steel or 6061-T6 aluminum alloy, with a thickness ranging from 1 mm to 4 mm.

[0020] In embodiments of this invention, a three-dimensional model of the target variable cross-section part can be constructed using CAD. Based on this three-dimensional model, spatial path features characterizing the geometric contour information of the part are further extracted. These extracted spatial path features are then used for core calculations in motion planning. For example, spatial path features of arc segments and straight segments are extracted. Based on the geometric relationships corresponding to the arc segments, a functional relationship describing how the forming roller's motion trajectory and its attitude (such as rotation angle) change with the forming roller's position is constructed. These calculated functional relationships are then input into the RoboDK simulation software environment. The software generates simulation results of the forming roller's motion trajectory and its attitude changing with position, and verifies these simulation results, such as checking for collisions, path reachability, and attitude rationality. After the simulation results are verified, the RoboDK software can generate a motion program that can directly drive an industrial robot.

[0021] During the processing stage, the original flat sheet material can be fixed on the fixture, and then the industrial robot is controlled to drive the forming rollers according to the generated robot motion program to roll the original flat sheet material and gradually shape it into the target variable cross-section part.

[0022] In embodiments of the present invention, the original flat sheet material can be fixed to the fixture in the following manner: Clamp the original flat sheet material into the fixture, and align the bottom edge of the original flat sheet material with the bottom edge of the fixture; adjust the position of the original flat sheet material horizontally in the fixture until the starting point of the original flat sheet material and the fixture reference line are on the same straight line, and fix the original flat sheet material; wherein, the fixture reference line is located at the side edge of the fixture and is perpendicular to the bottom edge of the fixture.

[0023] Specifically, the original flat sheet material to be processed can be clamped into the fixture. The key to clamping is ensuring that the bottom edge of the original flat sheet material is aligned with the bottom edge of the fixture. After initial alignment, the position of the original flat sheet material needs to be further adjusted horizontally within the fixture, that is, parallel to the bottom edge of the fixture, so that the starting point on the sheet material is on the same straight line as the reference line on the fixture. It should be noted that the fixture reference line is a positioning reference line located at the side edge of the fixture, and its direction is perpendicular to the bottom edge of the fixture. Once it is confirmed that the starting point of the original flat sheet material is collinear with the fixture reference line, the original flat sheet material can be fixed in place to ensure that its position is stable and does not shift during the subsequent rolling process, laying the spatial foundation for the robot to drive the forming rollers for rolling according to the program.

[0024] It is understandable that in the industrial robot roll forming process, ensuring that the starting point of the original flat sheet metal and the fixture reference line are on the same straight line is the core foundation for achieving high-precision machining. Its essence lies in establishing a unified spatial reference between the physical world and the digital model. By forcibly binding the sheet metal clamping starting point, the fixture positioning origin, and the robot path initial coordinates, the risk of overall trajectory deviation is fundamentally eliminated.

[0025] In embodiments of the present invention, before controlling the robot to roll the original flat sheet material according to the robot motion program, the following may be included: A global coordinate system is established, with the origin at the starting point of the original flat sheet material, the x-axis at the line passing through the origin and parallel to the bottom edge of the fixture, and the z-axis at the line passing through the origin and parallel to the side edge of the fixture. The coordinate positions of the forming roller and the support roller are calibrated. The positions of the forming roller and the support roller are adjusted synchronously until the starting point of the forming roller's motion trajectory coincides with the starting point of the original flat sheet material on the fixture. The robot motion program is loaded into the robot controller, and the forming roller is driven to run along the forming roller's motion trajectory without moving. The consistency between the forming roller's no-run trajectory and the motion trajectory is checked. If they are inconsistent, the forming roller's pose is adjusted until the forming roller's no-run trajectory and the motion trajectory are consistent.

[0026] It is understandable that after clamping the original flat sheet metal, a unified motion reference needs to be established. A global coordinate system is established with the starting point of the original flat sheet metal as the origin: the x-axis is defined as a line passing through the origin and parallel to the bottom edge of the fixture; simultaneously, the z-axis is defined as a line passing through the origin and parallel to the side edge of the fixture. After establishing the global coordinate system, the three-dimensional spatial coordinate positions of the forming roller and the support roller in the global coordinate system are measured and calibrated. Then, the spatial positions of the forming roller and the support roller are adjusted synchronously until the theoretical starting point of the forming roller's motion trajectory completely coincides with the starting point of the original flat sheet metal on the fixture (i.e., the origin of the coordinate system) in three-dimensional space, ensuring the absolute accuracy of the processing starting position.

[0027] After hardware positioning is completed, the pre-generated robot motion program is loaded into the robot controller. To verify the compatibility between the program and the physical system, the forming roller is driven to run along the preset forming roller trajectory. During this process, the actual running trajectory of the forming roller is monitored and checked in real time to ensure that it is completely consistent with the theoretical trajectory. If any inconsistency is observed, such as positional deviation or attitude offset, the pose parameters of the forming roller need to be adjusted, such as the tool center point TCP calibration value and rotation angle compensation. The running verification and parameter correction are iteratively executed until the error between the actual running trajectory and the theoretical trajectory of the forming roller is less than the preset value across the entire path.

[0028] In an embodiment of the present invention, controlling a robot to roll the original flat sheet material can be achieved through the following steps: The rolling process is divided into several passes. The forming rollers on the robot are controlled to roll the original flat sheet material in the first pass along the roller movement trajectory in the first posture. The posture of the forming rollers is adjusted and controlled to roll the sheet material in the Nth posture along the roller movement trajectory until all passes of rolling are completed.

[0029] Specifically, to achieve progressive forming of variable cross-section parts, the overall rolling process can be divided into several passes. In the first pass, the forming rollers on the robot are controlled to perform the first pass of rolling on the original flat sheet metal along a pre-generated roller motion trajectory in a first posture. Basic plastic deformation can be applied to the sheet metal to initially establish the cross-sectional profile. Then, based on the target cross-sectional geometry and material springback prediction, the posture parameters of the forming rollers, such as roller tilt angle, yaw angle, and pitch angle, are adjusted to control the forming rollers to perform subsequent passes of rolling on the sheet metal along the motion trajectory in an optimized posture. The rolling depth, rolling force, and posture parameters of each pass can be adjusted according to the process curve gradient to ensure that the material strain rate is within a safe threshold. This process is iterated until all preset passes of rolling are completed, ultimately enabling the sheet metal to accurately conform to the target three-dimensional curved surface through progressive cumulative plastic deformation, while effectively suppressing springback distortion through multi-pass path re-pressing.

[0030] In embodiments of the present invention, path continuity can be maintained between each stage.

[0031] It is understandable that in the industrial robot roll forming process, the continuity of the path between passes is the core to ensure the geometric integrity and mechanical stability of the part. By eliminating the trajectory interruption between passes, it keeps the material in a state of gradual and coordinated controlled deformation. This avoids the risk of local springback or instability caused by sudden stress changes, and ensures the precise accumulation of deformation and seamless connection of shape correction effects across multiple passes, thereby achieving uniform material rheology and stable contour forming in complex variable cross-section structures. Unlike the stress imbalance and geometric distortion caused by traditional segmented roll forming, the embodiments of this invention can fundamentally solve the industry problem of uncontrolled precision in complex structural parts.

[0032] In embodiments of the present invention, when processing multi-type variable cross-section parts, the process may further include: A 3D model of each type of variable cross-section part is established, and the spatial path features of each type of variable cross-section part are extracted from the 3D model. Based on each spatial path feature, a functional relationship is constructed between the motion trajectory of multiple forming rollers and their attitude as the position of the forming rollers changes. The multiple functional relationships are input into RoboDK simulation software to generate simulation results of the motion trajectory of multiple forming rollers and their attitude as the position of the forming rollers changes, and the simulation results are verified. Based on the verified simulation results, a robot motion program corresponding to each type of variable cross-section part is generated. The robot motion program is saved as a file corresponding to each type of variable cross-section part, and the file name is unified to a format that the system can recognize as the part type. The original flat sheet is fixed in the fixture, and the required processing model is selected in the system HMI interface. The system automatically loads the corresponding robot motion program and controls the robot to roll the original flat sheet according to the robot motion program.

[0033] Specifically, to meet the flexible production needs of various types of variable cross-section parts, embodiments of the present invention also provide the following processing technology: First, a 3D model is created for each type of target part using CAD. Then, based on the 3D model of each type, key spatial path features can be extracted using geometric topology analysis algorithms. Subsequently, based on the spatial path features of different types of variable cross-section parts, the motion trajectory and attitude of the forming rollers corresponding to different types of variable cross-section parts are constructed as a function of the changing position of the forming rollers, thus realizing model-specific motion planning.

[0034] Then, multiple sets of functional relationships are input into the RoboDK simulation environment to automatically generate simulation results of the motion trajectory and attitude of each roller model as the position of the forming roller changes. The simulation results are then verified in engineering through collision detection, reachability verification, and dynamic analysis. Based on the verified simulation data, robot motion programs matching each model are generated.

[0035] The program files are categorized and saved according to model, and a unified system-recognizable naming format (such as "Spar_TypeA_V2.src") is adopted to establish a structured program library. During actual processing, the operator can clamp the original flat sheet metal into a universal fixture, directly select the processing target from the part model list in the system HMI interface, and the control system automatically retrieves the robot motion program from the corresponding named file, driving the forming rollers to perform fully automatic rolling on the sheet metal according to a predetermined trajectory and posture, realizing rapid and seamless switching production of multiple types of parts.

[0036] The present invention also provides an industrial robot roll forming equipment for variable cross-section parts, comprising: Clamps are used to hold the original flat sheet material in place; The robot is located on both sides of the original flat sheet and is equipped with forming rollers and supporting rollers; the forming rollers act on the outer surface of the original flat sheet and the supporting rollers act on the inner surface of the original flat sheet.

[0037] The support rollers can move synchronously with the forming rollers without relative displacement. The support rollers also act as molds and / or fixtures during the forming process to improve the local rigidity of the sheet metal during rolling.

[0038] This invention applies industrial robot technology to the roll forming process of variable cross-section parts, filling a gap in this technological field. Traditional roll forming processes rely on fixed molds and preset paths, making it difficult to handle situations where the cross-section of the part changes along its length, thus limiting the manufacturing capability of variable cross-section parts. By introducing industrial robots, this invention can dynamically adjust the roll forming path according to the variable cross-section characteristics of the part, thereby achieving efficient processing. This technological breakthrough overcomes the limitations of existing processes in processing complex geometries, enabling industrial robots to perform high-quality, high-precision roll forming of complex variable cross-section parts without relying on molds.

[0039] Furthermore, this invention significantly improves the forming accuracy of variable cross-section parts by combining the robot's flexible path control capabilities with a real-time error compensation mechanism. In traditional roll forming processes, problems such as dimensional deviations and shape instability often occur due to the rigidity limitations of the mold and path. This invention, however, effectively controls forming errors during processing by adjusting the forming path in real time during the roll forming process, optimizing the path and compensating for errors based on the actual deformation of each pass, thus ensuring the stability and consistency of the part's geometry.

[0040] This invention is also particularly suitable for small-batch, multi-variety customized production of parts, offering high flexibility. Compared to traditional processes, this invention reduces the number of mold changes and enables the processing of parts with different cross-sections in a shorter time, meeting the demands of modern manufacturing for diversified and customized production. Especially in the automotive and aerospace industries, where the demand for complex structural parts is increasing, this invention provides a flexible, efficient, and low-cost manufacturing solution, significantly improving the economy and feasibility of small-batch production.

[0041] Furthermore, this invention simplifies the production process and reduces production costs by reducing reliance on traditional molds. Traditional processes require numerous molds and specialized equipment, and necessitate frequent mold adjustments and replacements, which not only increases production costs but also extends the production cycle. In contrast, the industrial robot system used in this invention can adjust its path according to the needs of different parts, thereby reducing the consumption of molds and tools, optimizing the production process, and improving overall production efficiency.

[0042] In summary, by introducing industrial robots into the roll forming process of variable cross-section parts, this invention not only achieves significant advantages in processing accuracy, production flexibility, and cost control, but also provides a new technical path for the efficient and precise manufacturing of variable cross-section parts, with broad engineering application prospects and market value.

[0043] For ease of understanding, the present invention also provides the following embodiments and comparative examples: Example

[0044] like Figure 2 As shown, the target part processed in this embodiment includes a double circular arc transition section, a height difference structure, and multiple straight sections, which are typical spatial variable cross-section structural parts.

[0045] like Figure 1 As shown, the device used includes: forming rollers; support rollers; two rollers are distributed on the upper and lower sides of the sheet material, and the sheet material is fixed on the working platform by a clamp.

[0046] The part is formed from a sheet metal through multiple roll forming processes. The sheet metal is made of low-carbon steel with a thickness of 2.0 mm and a length of approximately 600 mm. The part structure, from left to right, includes: an initial straight section AB (length L2, parallel to EF), a first circular arc transition section BC, a slanted straight section CD, a second circular arc transition section DE, and a final straight section EF (length L3). The radii of the first and second circular arc sections are both R, with centers O1 and O2 respectively. The two centers are at a horizontal distance L0 and have a vertical height difference L1. The overall structure forms a spatial variable-height structure with a height difference of D. See details... Figure 2 and Figure 4 .

[0047] S1: Path Modeling and Trajectory Generation A 3D model of the target part was constructed using CAD, and the spatial path features of the arc and straight segments were extracted. Based on the geometric relationship corresponding to the curved segments, the roller trajectory and its attitude change function with position during the forming process were constructed. The trajectory was designed and verified using RoboDK simulation software, which divided the rolling process into 14 passes. In each pass, the roller rolled along the path segment in different attitudes. The attitude control and position accuracy were dynamically planned in the trajectory, and the KUKA robot motion program was automatically generated.

[0048] S2: Clamping and Preparation Clamp the original flat sheet material into the fixture, aligning the clamping position with the starting point A, and set the coordinate system to match the initial pose of the robot path. Complete the tool coordinate calibration and trajectory program loading, and check the consistency between the roller position and the path.

[0049] S3: Multi-pass roll forming The robot initiates a trajectory program to collaboratively execute the rolling process: the forming rollers are responsible for advancing the upper pressing trajectory, while the support rollers support the path points below; the forming speed is set to 25 mm / s, and the forming force is maintained in the range of 900–1200 N. The rollers gradually push the material along the set path to form the material, maintaining path continuity between each pass.

[0050] The final formed parts, such as Figure 4 As shown, the spatial bending is smooth, the transition between the arc segment and the straight segment is natural, and there are no obvious creases or stress concentration points. Dimensional measurement results show that the final part's height difference D deviates from the design value by less than ±0.5 mm, the arc segment transition is smooth, and the cross-sectional profile error is less than ±0.4 mm, meeting the high-precision forming requirements of complex structural parts.

[0051] Comparative Example 1 To verify the superiority of the industrial robot rolling method of this invention in the processing of complex structural parts, this comparative example uses an existing industrial robot rolling system to attempt to process the same part structure. The results are as follows: Figure 6 As shown.

[0052] The sheet material used in this comparative example is the same as that in Example 1, and the fixture structure is the same. However, the system control capability is limited and it cannot automatically interpolate complex path changes. Path programming requires manual segmentation.

[0053] S1: Path Preparation and Assembly After extracting the part path using CAD, the control system was unable to recognize a continuous path containing two arc segments, a slanted straight section, and a height difference structure. The operators attempted to split the entire path into five segments for splicing, including two arc segments, two slanted straight sections, and a termination segment. Each segment required separate settings for its starting pose, roller angle, and speed parameters. The trajectory file splicing took approximately 10 hours, and issues with discontinuous poses and abrupt transitions still existed.

[0054] S2: Clamping and Trial Run The clamping process was the same as in Example 1, but during the preview of the running path, path offsets were found in several splicing segments, especially at the turns of BC and CD, and DE and EF, where sudden changes in roller posture caused the risk of path interruption. After three on-site adjustments, the problem of discontinuous motion trajectory still existed.

[0055] S3: Rolling execution and failure An attempt was made to execute the rolling process. Midway through the sixth pass, the forming rollers deviated from their path, causing them to fail to adhere to the sheet metal and jump around. The second arc segment (DE) was severely underformed, and the EF segment broke due to springback. The final part... Figure 6 As shown, the contour distortion is severe, the critical dimension error is greater than ±2 mm, and the springback angle error exceeds 7°, making it unusable.

[0056] This comparative example verifies the limitations of traditional industrial robot rolling systems in terms of path interpolation capability, continuous trajectory control, and adaptability to complex structures, making it difficult to automatically form high-precision double-bend + height difference structural parts.

[0057] A direct comparison between Example 1 and Comparative Example 1 is shown in Table 1. Table 1 The dimensions of the parts are shown in Table 2. Table 2 Example

[0058] A rapid form changeover method for industrial robot rolling of multi-type variable cross-section parts is disclosed. This embodiment is applicable to various variable cross-section parts with similar structures but different dimensional parameters. By loading a pre-generated trajectory file, form changeover can be achieved within minutes, demonstrating the high flexibility and responsiveness of the industrial robot system in customized scenarios.

[0059] The sheet metal used in this embodiment is 2.0 mm thick low-carbon steel. The geometric structures of the three parts to be processed are as follows: Figure 7 As shown. Figure 7 This is a schematic diagram of path reuse and rapid switching for robot processing of multiple types of variable cross-section parts in Embodiment 2 of the present invention. Switching between different types (A / B / C) does not require changing the fixture or reprogramming, the trajectory is consistent, and the path loading time is less than 3 minutes.

[0060] The equipment structure is the same as in Example 1, consisting of two six-axis industrial robots carrying forming rollers and support rollers respectively, working in tandem. The rolling trajectories for the three models are generated by RoboDK simulation and pre-stored in the control system.

[0061] The specific process flow is as follows: S1: Trajectory Modeling and Transformation Preparation Each part model is created using CAD and imported into RoboDK. The number of passes is set to 12 for each part, and the trajectory for each pass is generated independently and saved as a file corresponding to the part type. The files are named in a uniform format, allowing the system to recognize the corresponding part type.

[0062] S2: Selection and Trajectory Loading Select the desired machining model in the system's HMI interface, and the system will automatically load the corresponding trajectory program. Operators do not need to change fixtures, rollers, or recalibrate; they only need to perform trajectory verification and tool point confirmation. The switching process takes no more than 3 minutes.

[0063] S3: Perform roll forming The trajectory control program is executed, and the forming roller and support roller work together to perform multiple rolling passes, with speed and force parameters consistent with those in Example 1. All three models can successfully complete the path execution.

[0064] The results showed that the contours of the three parts were continuous, the dimensional error was controlled within ±0.5 mm, and no local collapse or severe springback problems were found. The entire changeover and processing process was completed within 15 minutes, demonstrating the significant advantages of the robotic rolling system in rapid switching between multiple models.

[0065] Comparative Example 2 This comparative example uses a traditional flexible roll forming system. When faced with batch switching tasks for multiple models of variable cross-section parts, it requires multiple steps such as fixture replacement, path reprogramming, and manual calibration. The response speed is slow and the efficiency is low, making it unable to meet the manufacturing needs of rapid model changeover.

[0066] The three target parts selected have the same structure as those in Example 2. The equipment structure is a flexible roller press, equipped with a CNC bending mechanism and an adjustable roller assembly. The control system uses a conventional CNC program, and machining paths need to be programmed separately for each model.

[0067] The specific operating procedure is as follows: S1: Part Path Reprogramming and Equipment Settings Based on the structures of the three parts (models A, B, and C), the machining programs were rewritten sequentially using programming software. Due to the coupling of width and angle variations, manual segmented control and process parameter setting were required, with the overall programming time being approximately 3–4 hours. For different models, the roller spacing and guide positioning devices also needed adjustment.

[0068] S2: Changeover Preparation and Tooling Adjustment When switching models, the fixture needs to be replaced, and the roller position and program start point need to be reset, requiring manual measurement and adjustment. Each switch takes approximately 30 minutes or more, and the overall reset time for the equipment is much longer than that of a robot system.

[0069] S3: Roller burnishing execution During the processing, the contact stability between the rollers and the sheet metal is relatively low, and slight slippage is prone to occur when the path is discontinuous, requiring timely manual intervention for correction. After processing, the dimensional error is approximately ±1.5 mm, and there is some springback or collapse at the edges. The total cycle time for switching between the three models exceeds 90 minutes.

[0070] This comparative example shows that although traditional flexible roll forming systems have a certain degree of adjustment capability, in application scenarios involving rapid switching between multiple parts models, path reprogramming and tooling adjustment take a long time and are complex to operate, which is not conducive to the development of small-batch customized production mode.

[0071] The intuitive comparison between Example 2 and Comparative Example 2 is shown in Table 3. Table 3 Example

[0072] In this embodiment, under the same structural and process conditions as in Embodiment 1, three metal sheet materials with different properties were selected: 6061-T6 aluminum alloy, ST12 cold-rolled steel, and AZ31B magnesium alloy, to verify the adaptability and stability of the industrial robot roll forming process proposed in this embodiment under multi-material systems. Specific forming results are shown in Table 4.

[0073] This embodiment verifies the high practicality and forming consistency of the roll forming process of the present invention under different material systems. Without changing equipment or adjusting the structure, it can achieve high-precision (≤±0.7 mm), high-consistency, and high-efficiency roll forming of variable cross-section parts, suitable for the diverse manufacturing needs of materials in multiple fields such as automotive, aerospace, and rail transportation. Table 4 The above provides a detailed description of the industrial robot roll forming process and equipment for variable cross-section parts. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An industrial robot roll forming process for variable cross-section parts, characterized in that, The process includes: Construct a three-dimensional model of the target variable cross-section part, and extract the spatial path features of the target variable cross-section part based on the three-dimensional model; Based on the aforementioned spatial path characteristics, a functional relationship is constructed between the motion trajectory of the forming roller and its attitude as a function of the position of the forming roller. The functional relationship is input into RoboDK simulation software to generate simulation results of the motion trajectory and attitude of the forming roller as the position of the forming roller changes, and the simulation results are verified. Based on the verified simulation results, a robot motion program is generated; The original flat sheet is fixed in the fixture, and the robot is controlled to roll the original flat sheet according to the robot motion program. The original flat sheet material is a metal sheet material with a thickness ranging from 1 mm to 4 mm.

2. The process according to claim 1, characterized in that, The step of fixing the original flat sheet material to the fixture includes: The original flat sheet is clamped into the fixture, and the bottom edge of the original flat sheet is aligned with the bottom edge of the fixture; Adjust the position of the original flat sheet material horizontally in the fixture until the starting point of the original flat sheet material is on the same straight line as the reference line of the fixture, and fix the original flat sheet material. The fixture reference line is located at the side edge of the fixture and is perpendicular to the bottom edge of the fixture.

3. The process according to claim 2, characterized in that, Before the robot is controlled to roll the original flat sheet material according to the robot motion program, the following steps are included: A global coordinate system is established with the starting point of the original flat sheet material as the origin, the line passing through the origin and parallel to the bottom edge of the fixture as the x-axis, and the line passing through the origin and parallel to the side edge of the fixture as the z-axis. The coordinate positions of the forming roller and the support roller are calibrated; The positions of the forming roller and the supporting roller are adjusted synchronously until the starting point of the forming roller's movement trajectory coincides with the starting point of the original flat plate on the fixture; The robot motion program is loaded into the robot controller, and the forming roller is driven to run along the motion trajectory of the forming roller without moving. The aiming is to check whether the empty running trajectory of the forming roller is consistent with the motion trajectory. If they are not consistent, the position of the forming roller is adjusted until the empty running trajectory of the forming roller is consistent with the motion trajectory.

4. The process according to claim 3, characterized in that, The controlled robot rolls the original flat sheet material, including: The rolling process is divided into several passes, and the forming rollers located on the robot are controlled to perform the first pass of rolling on the original flat sheet material along the roller movement trajectory in a first posture. Adjust the posture of the forming roller and control the forming roller to roll the sheet material along the roller movement trajectory in the Nth posture until all rolling passes are completed.

5. The process according to claim 4, characterized in that, The paths remain continuous between each of the aforementioned routes.

6. The process according to claim 5, characterized in that, The forming speed is set to 25 mm / s.

7. The process according to claim 1 or 6, characterized in that, In the case of machining multiple types of variable cross-section parts, the process further includes: Establish a three-dimensional model of each type of variable cross-section part, and extract the spatial path features of each type of variable cross-section part based on the three-dimensional model; Based on the spatial path features, a functional relationship is constructed between the motion trajectories of multiple forming rollers and their attitudes as the position of the forming rollers changes. The multiple functional relationships are input into RoboDK simulation software to generate multiple simulation results of the motion trajectory of the forming rollers and the change of their posture with the position of the forming rollers, and the simulation results are verified. Based on the verified simulation results, robot motion programs corresponding to each type of variable cross-section part are generated. Save the robot motion program as a file corresponding to each type of variable cross-section part, and unify the file name to a format that the system can recognize the part type; The original flat sheet is fixed in the fixture. The required processing model is selected in the system HMI interface. The system automatically loads the corresponding robot motion program and controls the robot to roll the original flat sheet according to the robot motion program.

8. An industrial robot roll forming equipment for variable cross-section parts, characterized in that, The device includes: Clamps are used to hold the original flat sheet material in place; A robot is located on both sides of the original flat sheet material and is equipped with forming rollers and supporting rollers; wherein the forming rollers act on the outer surface of the original flat sheet material and the supporting rollers act on the inner surface of the original flat sheet material.

9. The device according to claim 8, characterized in that, The support roller moves synchronously with the forming roller.

10. The device according to claim 9, characterized in that, The support rollers are also used to act as molds and / or fixtures during the forming process.

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