Composite u-flanging tooling and forming method

Abstract

This invention discloses a composite material U-shaped flanging fixture and forming method, comprising: a machine tool, a collaborative robot, and a U-shaped flanging end; the U-shaped flanging end includes: a connecting flange, a constant force flange, a modular forming platen, an electric cylinder, and a clamping roller; the connecting flange is used to connect the U-shaped flanging end to the collaborative robot, and a constant force flange is provided below it; the constant force flange has a built-in pressure sensor, displacement sensor, and gyroscope attitude sensor, and the output end of the constant force flange is connected to the servo electric cylinder, which drives the modular forming platen to perform compaction and bonding actions; the clamping roller is connected to the housing of the electric cylinder; the modular forming platen includes a fixed forming platen and a movable forming platen, both mounted on a base driven by the electric cylinder, the fixed forming platen being fixed on the base, and the movable forming platen being mounted on the base via a horizontal linear guide pair. This invention ensures forming accuracy while significantly improving changeover efficiency and the level of automation in process connection.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding and processing equipment, and in particular, a composite material U-shaped flange tooling and molding method. Background Technology

[0002] In the manufacturing of composite components such as aero-engine casings and spacecraft tanks, U-shaped grooves serve as critical connecting and reinforcing structures, and their forming quality directly affects the overall strength of the components. Currently, the industry mainly employs the following technical solutions for U-shaped flange processing:

[0003] 1. Manual Forming + Mold Pressing Mode: Operators first manually lay the composite prepreg onto the surface of a U-shaped mold, then apply pressure (usually 500-1000N) using a hydraulic press to complete the forming. This mode has low forming accuracy, relies heavily on manual laying precision, and is prone to layup wrinkles and air bubbles, resulting in U-groove height deviation ≥ ±1mm, width deviation ≥ ±2mm, and a layer loss area width ≥ 80mm. This fails to meet the design requirements of "U-shaped flange height ≥ 35.6mm, width ≥ 52.8mm (≤38mm after laying), and layer loss area ≤ 60.8mm". Furthermore, this mode has low changeover efficiency; molds need to be customized for different U-groove sizes, with changeover time ≥ 2 hours, making it unsuitable for mass production of multi-specification workpieces.

[0004] 2. Single-function automated molding equipment: Some equipment uses robots equipped with fixed U-shaped molding fixtures, such as the U-groove molding device disclosed in patent CN202221876543.2, which uses cylinders to drive pressure plates to compact composite materials. However, it has the following limitations: Coarse pressure control: The rigid pressure applied by cylinders lacks a flexible buffer layer on the pressure plate, resulting in pressure fluctuations within ±50N. This easily leads to composite layer collapse (uneven compaction when the layer thickness is 7.4mm) or weak adhesion; Poor curvature adaptation: For U-grooves in irregularly shaped rotating barrels, the fixture cannot adapt to changes in the workpiece surface curvature, resulting in side-to-side fit ≤ 85%, affecting structural strength. Furthermore, it cannot sense the molding pressure and the fit status of the groove bottom in real time, leading to a U-groove width tolerance typically ≥ ±2mm and a layer loss area width ≥ 80mm, making it difficult to meet high-precision requirements; Cumbersome process connections: The equipment and the flanging process are deployed independently, requiring workpiece transfer. This results in low process connection efficiency, with workpiece transfer time ≥ 30 seconds. It takes minutes and is prone to positioning errors (±0.5mm or more).

[0005] In addition, existing technologies have significant deficiencies in pressure control and trajectory adaptation for U-groove forming: most equipment uses fixed pressure output and cannot dynamically adjust the pressure according to the thickness of the composite layer (e.g., 7.4mm); for U-grooves of irregularly shaped rotating barrels, the tooling cannot adapt to changes in workpiece curvature, which easily leads to loose side fit and U-groove width deviation exceeding the design range after forming (requiring ≤38mm after laying). Summary of the Invention

[0006] The purpose of this invention is to provide a composite material U-shaped flange tooling and forming method to solve the problems of low forming accuracy, slow changeover, rough pressure control, poor curvature adaptation and complicated process in the prior art.

[0007] The technical solution to achieve the purpose of this invention is as follows:

[0008] A composite material U-shaped flange tooling, comprising:

[0009] Machine tools are molds used to hold workpieces to be processed.

[0010] The collaborative robot is used to connect the end of the U-shaped flange, move the end of the U-shaped flange to the U-shaped groove of the mold of the workpiece to be processed, and adjust the posture of the end of the U-shaped flange so that the modular forming platen fits into the U-shaped groove.

[0011] The U-shaped flange end includes: a connecting flange, a constant force flange, a modular forming pressure plate, an electric cylinder, and a clamping roller;

[0012] The connecting flange is used to connect the U-shaped flange end to the collaborative robot, and a constant force flange is provided below it. The constant force flange has built-in pressure sensors, displacement sensors, and gyroscope attitude sensors. The pressure and displacement sensors are used to monitor the forming pressure and pressing depth of the modular pressing plate in real time during the pressing process, realizing coordinated control of pressure and position. The gyroscope attitude sensor senses the curvature change of the workpiece mold in real time, providing posture adjustment feedback for the robot. The output end of the constant force flange is connected to a servo electric cylinder, which drives the modular forming pressing plate to perform compaction and bonding actions. The clamping roller is connected to the housing of the electric cylinder and is used to pre-compress the composite layup before the modular forming pressing plate presses into the U-shaped groove, and slides relative to the composite layup during the pressing process to perform tensioning and material replenishment. The modular forming pressing plate includes a fixed forming pressing plate and a moving forming pressing plate, both of which are installed on the base driven by the electric cylinder. The fixed forming pressing plate is fixed on the base and is used to bond the U-shaped flange end during the pressing process. The side wall of the U-shaped groove is pressed down to the bottom of the groove; the movable forming plate is mounted on the base through a horizontal linear guide pair, and can slide horizontally relative to the base and the fixed plate under the drive of the drive mechanism. It is used to move towards the side wall of the U-shaped groove when the modular forming plate is pressed down to the bottom of the groove.

[0013] The control computer of the collaborative robot is equipped with a U-shaped flanging offline programming and simulation system, which supports the import of the mold model of the workpiece to be processed, automatic generation of U-shaped groove trajectory, curvature adaptation path planning and collision interference detection.

[0014] The significant advantages of this invention compared to existing technologies are:

[0015] By using a modular flexible forming structure, integrating a high-precision force-sensing conformal compaction device, and motion control that adapts to the curvature of the workpiece, the system achieves rapid adaptation of U-groove dimensions, precise dynamic control of forming pressure, and high-fit forming of irregular curved surfaces. This significantly improves changeover efficiency and automation of process connections while ensuring forming accuracy, comprehensively solving the problems of low forming accuracy, slow changeover, coarse pressure control, poor curvature adaptation, and cumbersome processes in existing technologies. Attached Figure Description

[0016] Figure 1 This is a layout diagram of the composite material U-shaped flange tooling.

[0017] Figure 2 This is a schematic diagram of the U-shaped flange modular molding end structure.

[0018] Figure 3 This is a schematic diagram of the end motion of the U-shaped flange modular forming process. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] Combination Figures 1-3 This invention provides a composite material U-shaped flanging fixture and forming method. The core idea is to achieve high-precision automated forming of U-shaped grooves using an integrated architecture of "mobile leveling platform + collaborative robot + U-shaped flanging modular forming end + constant force sensing control + offline process simulation". Specifically, the composite material U-shaped flanging fixture of this invention includes a machine tool 1, a mobile carriage 2, a collaborative robot 3, and a U-shaped flanging end 4. The mobile carriage 2 is used to carry the collaborative robot 3. The end of the collaborative robot 3 integrates a U-shaped flanging end 4 consisting of "modular forming pressure plate + electric cylinder drive + constant force flange". Combined with an offline programming system to plan the curvature adaptation trajectory, it simultaneously realizes dynamic pressure adjustment and side edge fitting control, ultimately meeting the U-shaped flanging requirements of composite components of different specifications.

[0021] Machine tool 1 is the worktable of the wire laying equipment, used to fix the mold of the workpiece to be processed. During the processing, the mold is mounted on the machine tool, and the collaborative robot is positioned next to it by a moving carriage to perform U-shaped flanging on the workpiece.

[0022] The mobile trolley 2 is used to carry the collaborative robot 3 and transport it to the working position next to the workpiece. Its dimensions are 2000×1200×650mm. It adopts a configuration of "two sets of universal wheels + two sets of directional wheels" and uses an electric drive handle to control the movement (speed 0.5-1m / s). It is equipped with four leveling legs (leveling accuracy ±0.05°). When the load is 500KG, the maximum deformation is ≤0.6mm to ensure the stability of the collaborative robot 3 during operation.

[0023] The collaborative robot 3 is a Luoshi xMate CR35-35_2.2 with 6 degrees of freedom, a working radius of 2246mm, a repeatability of ±0.05mm, supports Cartesian space impedance control, has a force feedback accuracy of 0.5N, and can adjust the end effector posture in real time to adapt to the workpiece curvature.

[0024] The U-shaped flange end 4 includes an electric cylinder 8 (stroke 50mm, positioning accuracy ±0.02mm), a modular forming pressure plate (adapted to different U-shaped groove widths), a pressing roller 5 (φ20mm polyurethane material), a constant force flange, and a connecting flange;

[0025] The connecting flange is the mechanical interface between the end of the collaborative robot 3 and the U-shaped flange end 4. It is directly connected to the end of the collaborative robot 3 and is used to install the entire U-shaped flange end on the end of the robot. Starting from the end of the collaborative robot, connecting flanges serving as mechanical interfaces are connected sequentially downwards. Below it is a constant force flange with high-precision force sensing and control functions. The output end of the constant force flange is connected to a servo electric cylinder, which directly drives the lower modular forming plate to perform compaction and bonding actions. At the same time, the pressing rollers used for pre-pressing materials are mounted on the housing of the electric cylinder through a lateral bracket and work together under the control of the constant force flange.

[0026] The modular forming pressure plate includes a fixed forming pressure plate 6-1 and a movable forming pressure plate 6-2. Both are mounted on a mounting base driven by an electric cylinder push rod, allowing for vertical movement. The fixed forming pressure plate is rigidly mounted on this base, while the movable forming pressure plate is mounted on the base via a horizontal linear guide pair and can be driven by an independent horizontal small cylinder, enabling it to slide horizontally relative to the base and the fixed pressure plate. Both pressure plates are made of aluminum alloy (lightweight, weight ≤1.5KG), with a 5mm thick polyurethane buffer layer (Shore hardness adjustable from 10A to 75A, selected according to the composite material type, such as 40A hardness for carbon fiber composites) to prevent crushing of the composite material. Three pressure plate modules are available (adapting to initial U-shaped groove widths of 52.8mm, 60mm, and 70mm). The pressure heads of the fixed forming pressure plate 6-1 and the movable forming pressure plate 6-2 are connected by quick-release buckles, with a changeover time of <3 minutes, ensuring a smooth U-shaped groove after installation. The groove width is ≤38mm; a chamfer at a 15° angle to the horizontal plane is machined between the sides and bottom of the two pressure plates. When the moving forming pressure plate 6-2 extends horizontally and presses the composite layer against the side wall of the U-shaped groove, this 15° inclined surface can play a progressive guiding role, reducing the shear force when the composite is turned over and reducing the risk of layer loss.

[0027] The electric cylinder 8 is a servo electric cylinder with a thrust of 1000N, which can precisely control the pressing depth of the modular molding platen (accuracy ±0.02mm) to ensure that the modular molding platen fits snugly against the bottom of the U-shaped groove.

[0028] The clamping roller 5 is arranged on one side of the modular forming platen, using φ20mm polyurethane rollers and equipped with a return spring. The pre-pressure is adjustable from 50-100N by adjusting the spring compression or stiffness, used to fix the composite material position before forming to prevent layer displacement. The constant force flange, model HDAFC500-40, has a maximum force of 500N, a stroke of 40mm, and a force control accuracy of ±2N. It incorporates a pressure sensor (sampling frequency 100Hz), a displacement sensor, and a gyroscope attitude sensor. The pressure and displacement sensors monitor the forming pressure and pressing depth of the platen in real time during the pressing process, achieving coordinated pressure and position control. The gyroscope attitude sensor senses the curvature changes of the workpiece surface in real time, providing posture adjustment feedback for the robot. The data from these three sensors are synergistically integrated through the constant force flange to form an integrated "force-position-attitude" adaptive control system.

[0029] The control computer of the collaborative robot 3 is equipped with a U-shaped flange offline programming and simulation system. This system is developed based on the RoboDK platform and supports CAD model import (Creo / Catia / NX / SolidWorks), automatic generation of U-shaped groove trajectory, curvature adaptation path planning and collision interference detection (accuracy ±0.1mm).

[0030] The core idea of ​​the U-shaped groove trajectory generation, curvature adaptation, and collision detection algorithm can be summarized as follows: First, the system automatically identifies the geometric contour of the U-shaped groove through the CAD model, extracts the key coordinates and normal vectors of the groove bottom and sidewalls, and then plans the continuous motion trajectory of the robot end effector: "vertical downward pressure - translation along the sidewall - safe exit," ensuring a trajectory accuracy of ±0.05mm. Second, for the curvature changes of the irregular rotating workpiece surface, the system generates the target posture using the known workpiece CAD curvature information, feeds back the actual posture through a gyroscope posture sensor, and performs closed-loop correction. Simultaneously, pressure sensors are used for pressure closed-loop fine-tuning. These two mechanisms work together to achieve the robot end effector's posture adaptation to complex curved surfaces, ensuring that the forming platen maintains a high degree of contact (≥98%) with the groove wall during movement. Finally, before trajectory execution and during simulation, the system performs static and dynamic interference detection on the robot, end effector, workpiece, and surrounding equipment based on a bounding box collision detection engine. If a collision risk is detected, the system automatically optimizes the motion path or inserts obstacle avoidance points, achieving a detection accuracy of ±0.1mm, thus ensuring the safety and reliability of the processing.

[0031] The above tooling adopts a two-step process of "bottom compaction - side fitting" for U-shaped groove forming. The following control logic is designed:

[0032] 1. Compaction stage at the bottom of the trench:

[0033] The collaborative robot 3 moves the U-shaped flange end 4 to the U-shaped groove of the U-shaped groove workpiece 10. The clamping roller 5 contacts the surface of the composite material 9. The collaborative robot presses down and drives the clamping roller to output a pre-pressure of 50-100N to fix the composite material. The pressure value is determined by the pressure sensor in the constant force flange.

[0034] The electric cylinder 8 drives the modular forming plate to slowly press down (speed 0.5mm / s), and makes the fixed forming plate fit against one side wall of the U-shaped channel. At the same time, the pressing roller 5 moves (rotates only) to prevent the composite material from wrinkling and complete the tensioning and replenishment of the composite material. The pressure sensor in the constant force flange monitors the pressure at the end of the modular forming plate in real time by sensing the reaction force of the channel wall on the forming plate. When the pressure reaches 100-300N (adjusted according to the layup thickness, 200N is set for 7.4mm layup), the electric cylinder 8 stops pressing down and maintains the pressure for 3-5 seconds to ensure that the bottom of the channel is compacted.

[0035] 2. Side bonding stage:

[0036] A small cylinder drives the moving forming platen 6-2 to move horizontally along the side wall (speed 1mm / s), maintaining the material at the bottom of the U-shaped groove while tightly adhering the layer to the side wall and maintaining pressure for the set time.

[0037] When the cylinder pressure feedback increases (detecting that the modular forming plate is in contact with the edge of the groove), it is determined that the side bonding is complete. The cylinder stops moving, and the robot drives the U-shaped flange end 4 out of the U-shaped groove. During this process, the side of the modular forming plate is always in close contact with the side wall of the U-shaped groove.

[0038] The U-shaped flange offline programming and simulation system has the following functions:

[0039] 1. Automatic generation of U-shaped groove trajectory: After importing the workpiece CAD model, the system automatically identifies the U-shaped groove contour based on the workpiece CAD 3D model. At the same time, the coordinate information of the groove bottom and sidewall is obtained from the workpiece CAD model. The spatial position of the collaborative robot 3 and the modular forming platen is adjusted. The modular forming platen is pressed vertically down to the bottom of the groove. When the pressure sensor in the constant force flange detects that the pressure value borne by the modular forming platen reaches the preset value, the pressure is maintained for 3~5 seconds. The fixed forming platen 6-1 remains stationary, while the moving forming platen 6-2 moves along the bottom of the groove. When the cylinder air pressure feedback increases to the set value, the contact force between the pressing head of the moving forming platen 6-2 and the sidewall of the U-shaped groove reaches the target value. After maintaining this state for 3~5 seconds, the modular forming plates 6-1 and 6-2 are raised and withdrawn, generating the "press-translation-withdrawal" motion trajectory of the modular forming platen with a trajectory accuracy of ±0.05mm.

[0040] 2. Curvature Adaptation Path Planning: For the U-shaped groove of an irregularly shaped rotating barrel, during the offline programming stage, the CAD 3D model of the workpiece is imported. The system pre-calculates the ideal position and posture of each processing point on the sidewall of the U-shaped groove, generating a theoretical motion trajectory that ensures the pressure surface of the pressure plate head (the side of the pressure plate head when the U-shaped groove side is laid, and the bottom surface of the pressure plate head when the U-shaped groove bottom is laid) always applies pressure along the normal direction of its contact local curved surface. During the actual execution stage, adjustments are made in real time through posture and force feedback. The posture sensor on the constant force flange monitors the actual posture of the pressure plate in real time and compares it with the target posture of the corresponding point in the theoretical trajectory. The robot dynamically fine-tunes the wrist angle accordingly to ensure that the pressure plate is always aligned with the curved surface at the correct angle (pressing direction); the force sensor on the constant force flange monitors the contact pressure between the pressure plate and the sidewall in real time. Regardless of whether the pressure deviates from the set value due to minor surface unevenness or motion error, the system will immediately control the robot or constant force flange to finely adjust its position along the normal of the curved surface, thereby accurately maintaining the pressure within the process requirements range and ensuring that the forming platen is always in contact with the tank wall (contact ≥98%).

[0041] 3. Pressure Parameter Matching: Based on the relevant data from simulations and experiments regarding the thickness of the auxiliary material layup, the size of the U-shaped groove, the pressure borne by the forming platen, and the movement speed of the electric cylinder, a corresponding machine learning model for process parameters is formed. This model can output relevant process parameters such as the forming platen pressure (100-300N at the bottom of the groove and 200-500N at the side) and the movement speed of the electric cylinder 8, based on the input composite material layup thickness (e.g., 7.4mm) and U-shaped groove size.

[0042] 4. Collision Detection: Before trajectory execution and during simulation, the system uses a bounding box collision detection engine to perform static and dynamic interference detection on the robot, end tool, workpiece and surrounding equipment. If a collision risk is detected, the system automatically optimizes the motion path or inserts obstacle avoidance points. The detection accuracy reaches ±0.1mm, thereby ensuring the safety and reliability of the processing.

[0043] The composite material U-shaped flange forming method of the present invention includes the following steps:

[0044] Step S1: Workpiece positioning and tooling preparation

[0045] The mold of the composite component to be processed (such as the mold of the casing of an aircraft engine) is fixed on the machine tool 1. The tooling is moved to the side of the workpiece by the electric handrail of the moving carriage 2. The support legs are adjusted so that the horizontal error of the moving carriage 2 is ≤0.1°.

[0046] Select the appropriate modular forming platen pressure head according to the initial width of the U-shaped groove (e.g., 52.8mm), install it through quick-release buckles, and calibrate the relative position of the modular forming platen and the robot end effector after the changeover is completed (calibration accuracy ±0.02mm).

[0047] Start the offline programming system, import the workpiece digital model, set the layup thickness (7.4mm) and U-groove height (≥35.6mm), generate the forming trajectory program, and upload it to the robot control cabinet after simulation without interference.

[0048] Step S2: Pre-positioning and pre-pressurization

[0049] The collaborative robot 3 determines its spatial position based on the three-dimensional coordinates determined by the workpiece digital model and the coordinate system of the machine tool, and drives the U-shaped flange end 4 to move above the target U-shaped groove, so that the side of the fixed forming plate 6-1 is aligned with the side wall of the groove (alignment error ≤ ±0.1mm).

[0050] When the constant force flange 7 is activated, the pressure roller 5 is pressed down onto the surface of the composite material, outputting a preload of 80N to fix the position of the composite material and prevent the layers from shifting during subsequent molding.

[0051] Step S3: Compact the bottom of the trench

[0052] Servo electric cylinder 8 drives the modular forming platen to move downward at a speed of 0.5 mm / s, and constant force flange 7 monitors the pressure change in real time. When the pressure reaches 200 N and the displacement sensor detects that the modular forming platen is in contact with the bottom of the tank, electric cylinder 8 stops moving, and constant force flange 7 maintains 200 N pressure for 5 seconds to ensure that the composite material at the bottom of the tank is compacted (compaction degree ≥ 95%).

[0053] Step S4: Side bonding

[0054] The gyroscope attitude sensor and pressure sensor detect the actual attitude and contact pressure of the pressure plate in real time and feed it back to the collaborative robot 3; the collaborative robot 3 finely adjusts the position along the normal of the curved surface so that the side of the modular pressure plate fits the side wall of the U-shaped groove (fitting degree ≥98%).

[0055] The electric cylinder 8 drives the modular forming plate to move upward along the side wall at a speed of 1 mm / s, and the constant force flange 7 maintains the side pressure at 300 N; during the translation, the clamping roller 5 moves along and continuously applies a pre-pressure of 80 N to prevent the composite material from wrinkling.

[0056] When the electric cylinder current rises to the set threshold (determining that the pressure plate has left the edge of the U-shaped groove), the electric cylinder stops moving, and the side bonding is completed.

[0057] Step S5: Molding Inspection and Resetting

[0058] The robot drives the end effector to exit the U-shaped groove. The dimensions of the U-shaped groove are detected by an external laser profilometer (accuracy ±0.01mm): height 40mm (≥35.6mm) and width 37mm (≤38mm). The width of the layer loss area is detected by an external ultrasonic detector (55mm≤60.8mm).

[0059] If the inspection is successful, the robot moves the end effector to the next U-shaped groove and repeats steps S2-S5; if it fails, the cause of the error is analyzed (such as insufficient pressure or trajectory deviation), the relevant parameters are adjusted, and the molding is repeated.

[0060] Once all the U-shaped channels are formed, the robot resets and the mobile trolley is dragged to the standby position.

[0061] Example: U-shaped flange forming of aircraft engine casing body

[0062] 1. Workpiece parameters

[0063] Workpiece type: Cylindrical shell of an aircraft engine, made of carbon fiber reinforced resin matrix composite material (T800 / epoxy).

[0064] Dimensions: 1500mm diameter barrel, 2000mm length, 8 U-shaped channels, initial width 52.8mm, target height 40mm (≥35.6mm), and layup thickness 7.4mm;

[0065] Quality requirements: After laying, the width of the U-shaped groove should be ≤38mm, the width of the missing layer area should be ≤60.8mm, the compaction degree should be ≥95%, and the side adhesion degree should be ≥98%.

[0066] 2. Tooling Configuration

[0067] Mobile trolley: outriggers leveled to 0.08°, load capacity 500KG;

[0068] Collaborative robot: Rokae CR35, working radius 2246mm, repeatability ±0.05mm;

[0069] U-shaped flange end: forming pressure plate module (adapted to 52.8mm initial width), polyurethane buffer layer hardness 40A; servo electric cylinder stroke 50mm, positioning accuracy ±0.02mm; clamping roller φ20mm, preload 80N;

[0070] Constant force flange: Model HDAFC500-40, bottom pressure setting 200N, side pressure setting 300N, force control accuracy ±2N;

[0071] Offline programming system: Import the shell body digital model and automatically generate the forming trajectory of 8 U-shaped grooves, with collision detection accuracy of ±0.1mm.

[0072] 3. Processing procedure

[0073] Step 1: Fix the shell body to the filament laying worktable, move the trolley to the side of the shell body, and level the support legs; install the 52.8mm forming pressure plate and calibrate the end position (error 0.01mm).

[0074] Step 2: Import the digital model into the offline programming system, set the layer thickness to 7.4mm and the U-shaped groove height to 40mm, generate the trajectory program, and upload it to the robot after simulation without interference;

[0075] Step 3: The robot moves the end effector to the first U-shaped groove, the vision sensor is calibrated (alignment error 0.08mm), and the pressure roller is pressed down to output a pre-force of 80N;

[0076] Step 4: The electric cylinder drives the pressure plate to press down at 0.5mm / s. The constant force flange monitors the pressure. After reaching 200N and detecting the bottom of the tank, the pressure is maintained for 5 seconds.

[0077] Step 5: The gyroscope provides feedback on the curvature of the barrel (radius 1500mm), and the robot adjusts its posture to make the side of the pressure plate fit against the tank wall; the electric cylinder drives the pressure plate to move upward at 1mm / s, the constant force flange maintains a pressure of 300N, and the pressing roller moves accordingly;

[0078] Step 6: The electric cylinder current rises to the threshold and stops moving upwards; Laser profilometer detection: height 40.02mm, width 37.8mm; Ultrasonic detection: layer loss width 54mm, compaction degree 96%;

[0079] Step 7: The robot exits and moves to the next U-shaped groove, repeating steps 3-6; the total processing time for 8 U-shaped grooves is 62 minutes.

[0080] Step 8: After all U-shaped channels are completed, the robot is reset and the trolley is dragged to the standby position.

[0081] 4. Processing Results

[0082] Dimensional accuracy: Height deviation ±0.02mm, width deviation ±0.2mm, both meet design requirements;

[0083] Quality indicators: Layer width ≤ 54mm ≤ 60.8mm, compaction degree ≥ 95% ≥ 96%, side fit ≥ 98% ≥ 99%;

[0084] Efficiency indicators: The processing time for a single U-shaped groove is 7.75 minutes, which is 48% shorter than the existing technology (15 minutes); the changeover time is 2.5 minutes, which is 97.9% shorter than the existing technology (2 hours).

[0085] Existing technologies use fixed-specification molding plates, resulting in long changeover times (≥2 hours) and the lack of a flexible buffer layer, which can easily crush composite materials. This invention employs a quick-release modular molding plate (changeover time < 3 minutes), adaptable to U-shaped channels with initial widths of 52.8-70mm, and covered with a polyurethane buffer layer (adjustable hardness). This solves the problems of multi-specification adaptation and composite material protection, ensuring that the U-shaped channel width after installation is ≤38mm and the layer loss area is ≤60.8mm. Existing technologies use single pressure molding, which cannot simultaneously ensure the bonding quality of the channel bottom and sides. This invention uses a constant-force flange and a servo electric cylinder in synergy for phased control: the channel bottom stage primarily uses pressure control (100-300N, accuracy ±2N) to ensure compaction; the side stage combines position control (electric cylinder translation accuracy ±0.02mm) and curvature adaptation (robot posture adjustment ±0.05mm) to achieve a side bonding degree ≥98%, overcoming the limitation of low molding accuracy in existing technologies. Existing technologies cannot adapt to changes in the curvature of irregularly shaped workpieces, resulting in low side-fitting accuracy (≤85%). This invention utilizes a gyroscope attitude sensor built into the constant-force flange to provide real-time feedback on the workpiece curvature. The collaborative robot dynamically adjusts its end effector posture, ensuring the forming platen remains in contact with the groove wall. Even on irregularly shaped barrels with curvature radii of 1000-1700mm, the dimensional accuracy of the U-shaped groove is guaranteed (height deviation ±0.3mm, width deviation ±0.2mm). Existing simulation software cannot generate a "press-translate-exit" trajectory for the U-shaped groove, nor can it match pressure parameters. The software of this invention can automatically extract the U-shaped groove contour to generate a forming trajectory, match pressure parameters based on the layup thickness and groove size, achieve collision detection accuracy of ±0.1mm, and reduce on-site debugging time from ≥2 hours to ≤20 minutes, solving the problem of low efficiency in traditional programming.

Claims

1. A composite material U-shaped flange tooling, characterized in that, include: Machine tools are molds used to hold workpieces to be processed. The collaborative robot is used to connect the end of the U-shaped flange, move the end of the U-shaped flange to the U-shaped groove of the workpiece mold, and adjust the posture of the end of the U-shaped flange so that the modular forming platen fits into the U-shaped groove. The U-shaped flange end includes: a connecting flange, a constant force flange, a modular forming pressure plate, an electric cylinder, and a clamping roller; The connecting flange is used to connect the U-shaped flange end to the collaborative robot, and a constant force flange is provided below it. The constant force flange has built-in pressure sensors, displacement sensors, and gyroscope attitude sensors. The pressure and displacement sensors are used to monitor the forming pressure and pressing depth of the modular forming platen in real time during the pressing process, realizing coordinated control of pressure and position. The gyroscope attitude sensor senses the curvature change of the workpiece mold in real time, providing posture adjustment feedback for the robot. The output end of the constant force flange is connected to a servo electric cylinder, which drives the modular forming platen to perform compaction and bonding actions. The clamping roller is connected to the housing of the electric cylinder and is used to pre-compress the composite layer before the modular forming platen presses into the U-shaped groove, and slides relative to the composite layer during the pressing process to perform tensioning and material replenishment. The modular forming platen includes a fixed forming platen and a moving forming platen, both of which are installed on the base driven by the electric cylinder. The fixed forming platen is fixed on the base and is used to bond with the U-shaped flange end during the pressing process. One side wall of the U-shaped groove is pressed down to the bottom of the groove; the movable forming plate is mounted on the base through a horizontal linear guide pair, and can slide horizontally relative to the base and the fixed plate under the drive of the drive mechanism, so as to move to the other side wall of the U-shaped groove when the modular forming plate is pressed down to the bottom of the groove; The control computer of the collaborative robot is equipped with a U-shaped flanging offline programming and simulation system, which supports the import of the mold model of the workpiece to be processed, automatic generation of U-shaped groove trajectory, curvature adaptation path planning and collision interference detection.

2. The composite material U-shaped flange tooling according to claim 1, characterized in that, The implementation methods for automatic generation of U-shaped groove trajectories, curvature-adaptive path planning, and collision interference detection are as follows: The system automatically identifies the geometric contour of the U-shaped groove through the digital model of the workpiece mold. It obtains the coordinate information of the groove bottom and sidewalls from the mold, and then plans a continuous motion trajectory for the U-shaped flange end: "vertical downward pressure - translation along the sidewall - safe exit." Considering the curvature changes on the surface of the rotating workpiece mold, it uses known CAD curvature information to generate a theoretical motion trajectory that ensures the pressure surface of the modular forming platen's pressure head is always perpendicular to the local curved surface it contacts. During the actual forming stage, real-time adjustments are made through attitude and force feedback. The actual attitude of the modular forming platen is fed back by a gyroscope attitude sensor and compared with the target attitude at the corresponding point in the theoretical trajectory. The robot adjusts its attitude to ensure that the side / bottom edge of the modular forming platen is always perpendicular to the local curved surface it contacts. Combined with real-time monitoring of the contact pressure between the platen and the U-shaped groove sidewall by a force sensor, the robot's end-effector attitude adapts to the curved surface, ensuring the modular forming platen remains in contact with the groove wall during movement. Interference detection is performed before trajectory execution and during simulation to optimize the motion path.

3. The composite material U-shaped flange tooling according to claim 1, characterized in that, The pressure heads of the fixed forming plate and the movable forming plate are connected by quick-release buckles.

4. The composite material U-shaped flange tooling according to claim 1, characterized in that, A chamfer is machined between the side and the bottom of the pressure head.

5. The composite material U-shaped flange tooling according to claim 1, characterized in that, The clamping roller is made of polyurethane and equipped with a return spring, allowing for adjustable pressure.

6. The composite material U-shaped flange tooling according to claim 1, characterized in that, It also has a mobile cart to carry collaborative robots and move them to the work position next to the workpiece mold.

7. The composite material U-shaped flange tooling according to claim 6, characterized in that, The mobile trolley is equipped with two sets of omnidirectional wheels and two sets of directional wheels, as well as four leveling legs.

8. A method for forming a U-shaped flange of a composite material, characterized in that, The composite material U-shaped flange tooling according to any one of claims 1-7 includes: Fix the workpiece mold to be processed on the machine tool. Select and install the pressure head of the appropriate modular forming plate according to the initial width of the U-shaped groove. Calibrate the relative position of the modular forming plate and the robot end effector. Start the offline programming system, import the workpiece mold digital model, set the layup thickness and U-shaped groove height, generate the forming trajectory program, and upload it to the robot control cabinet after simulation without interference. The collaborative robot determines its spatial position by using the three-dimensional coordinates of the workpiece mold and the machine tool coordinate system. It then moves the end of the U-shaped flange to the top of the target U-shaped groove, aligning the side of the fixed forming plate with the side wall of the groove. The constant force flange is activated, controlling the pressing rollers to press down onto the composite material layup for pre-pressing. An electric cylinder drives the modular forming plate downwards, causing it to adhere to one side wall of the U-shaped channel, with the pressing rollers following suit. A constant-force flange monitors pressure changes in real time. When the pressure reaches a set value and the displacement sensor detects that the modular forming plate is in contact with the bottom of the channel, the electric cylinder stops moving, and the constant-force flange maintains the pressure for a set time. A gyroscope attitude sensor and a pressure sensor detect the actual attitude and contact pressure of the modular forming plate in real time, feeding this information back to the collaborative robot. The collaborative robot then fine-tunes the position along the normal of the curved surface, ensuring that the side of the modular forming plate adheres to the side wall of the U-shaped channel. The moving forming plate is moved horizontally to the other side wall of the U-shaped groove; The robot drives the end of the U-shaped flange out of the U-shaped groove for inspection of the formed workpiece.

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