Composite material U-shaped flanging tool and forming method

Abstract

The invention discloses a composite material U-shaped flanging tool and a forming method. The composite material U-shaped flanging tool comprises a machine tool, a collaborative robot and a U-shaped flanging tail end. The U-shaped flanging tail end comprises a connecting flange, a constant-force flange, a modular forming pressing plate, an electric cylinder and a pressing roller; the connecting flange is used for connecting the tail end of the U-shaped flange with the collaborative robot, and the constant-force flange is arranged below the connecting flange; a pressure sensor, a displacement sensor and a gyroscope attitude sensor are arranged in the constant-force flange, the output end of the constant-force flange is connected with a servo electric cylinder, and the electric cylinder drives a modular forming pressing plate to execute compaction and fitting actions; the pressing roller is connected with a shell of the electric cylinder; the modularized forming pressing plate comprises a fixed forming pressing plate and a movable forming pressing plate, the fixed forming pressing plate and the movable forming pressing plate are installed on a base driven by an electric cylinder, the fixed forming pressing plate is fixed to the base, and the movable forming pressing plate is installed on the base through a horizontal linear guide rail pair. The forming precision is guaranteed, and meanwhile the model changing efficiency and the automation level of procedure connection are greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of composite material forming processing equipment, in particular to a composite material U-shaped flanging tool and a forming method. BACKGROUND

[0002] In the manufacturing of composite material components such as aircraft engine casings and spacecraft tanks, the U-shaped groove as a key connection and reinforcement structure directly affects the overall strength of the component. Currently, the industry mainly uses the following technical solutions for U-shaped flanging processing:

[0003] 1. Manual forming + mold pressing mode: The operator first manually lays the composite prepreg on the surface of the U-shaped mold, and then completes the forming by applying pressure (usually 500-1000N) through a hydraulic machine. This mode has low forming precision and relies on manual laying accuracy, which is prone to layer wrinkles and bubbles, resulting in a U-shaped groove height deviation ≥ ±1mm, width deviation ≥ ±2mm, and layer loss area width ≥ 80mm, which cannot meet the design requirements of "U-shaped flange height ≥ 35.6mm, width ≥ 52.8mm (after laying ≤38mm), and layer loss area ≤ 60.8mm". At the same time, this mode has low changeover efficiency, as the mold needs to be customized for different U-shaped groove sizes, and the changeover time is ≥ 2 hours, which cannot adapt to batch production of multiple specifications of workpieces.

[0004] 2. Single-function automatic forming equipment: Some devices use robots to carry fixed U-shaped forming tools, such as the U-shaped groove forming device disclosed in patent CN202221876543.2, which uses a cylinder to drive a pressing plate to compact the composite material. However, it has the following limitations: rough pressure control: using a cylinder for rigid pressure, the pressing plate has no flexible buffer layer, and the pressure fluctuation range is ±50N, which can easily cause the composite material to be crushed (when the layer thickness is 7.4mm, the compaction degree is uneven) or not firmly attached; poor curvature adaptation: for U-shaped grooves of irregularly shaped rotary bodies, the tool cannot adapt to the curvature changes of the workpiece surface, and the side attachment degree is ≤ 85%, affecting the structural strength, and it cannot real-time sense the forming pressure and groove bottom attachment state, resulting in a U-shaped groove width tolerance usually ≥ ±2mm, and a layer loss area width ≥ 80mm, making it difficult to meet high precision requirements; complicated process connection: the device and the flanging process are independently deployed, which requires transferring the workpiece, has low process connection efficiency, and the workpiece transfer time is ≥ 30 minutes, and is prone to positioning errors (±0.5mm or more).

[0005] In addition, the prior art has obvious defects in pressure control and trajectory adaptation of U-shaped groove forming: most devices adopt fixed pressure output, which cannot dynamically adjust the pressure according to the composite layer thickness (such as 7.4mm); for the U-shaped groove of the special-shaped rotary barrel body, the tooling cannot adapt to the curvature change of the workpiece, and the side edge is prone to not fit tightly, and the width deviation of the formed U-shaped groove exceeds the design range (the requirement after laying is ≤38mm). SUMMARY

[0006] The purpose of the present application is to provide a composite material U-shaped flanging tool and forming method, which solves the problems of low forming precision, slow change, rough pressure control, poor curvature adaptation and complicated process in the prior art.

[0007] The technical solution for achieving the purpose of the present application is:

[0008] A composite material U-shaped flanging tool, comprising:

[0009] A machine tool for fixing a workpiece mold to be processed;

[0010] A collaborative robot for connecting a U-shaped flanging end, moving the U-shaped flanging end above the U-shaped groove of the workpiece mold to be processed, and adjusting the attitude of the U-shaped flanging end to make the modular forming press plate fit the U-shaped groove;

[0011] The U-shaped flanging end comprises a connecting flange, a constant force flange, a modular forming press plate, an electric cylinder and a pressing roller.

[0012] The connecting flange is used to connect the U-shaped flanging end with the collaborative robot, and a constant force flange is arranged below the connecting flange; the constant force flange is internally provided with a pressure sensor, a displacement sensor and a gyroscope attitude sensor; the pressure and displacement sensors are used to monitor the forming pressure and the depth of the modular press plate during the pressing process in real time, so as to realize the coordinated control of pressure and position; the gyroscope attitude sensor can sense the curvature change of the workpiece mold to be processed in real time, and provide attitude adjustment feedback for the robot; the output end of the constant force flange is connected with a servo electric cylinder, and the electric cylinder drives the modular forming press plate to perform the compaction and fitting action; the pressing roller is connected with the shell of the electric cylinder, and is used to pre-press the composite layer before the modular forming press plate is pressed into the U-shaped groove, and slide relative to the composite layer during the pressing process to tension the material; the modular forming press plate comprises a fixed forming press plate and a movable forming press plate, which are installed on the base driven by the electric cylinder; the fixed forming press plate is fixed on the base, and is used to press the side wall of the U-shaped groove to the bottom of the groove during the pressing process of the U-shaped flanging end; the movable forming press plate is installed on the base through a horizontal linear guide pair, and can slide horizontally relative to the base and the fixed press plate under the drive of the driving mechanism, and is used to move towards the side wall of the U-shaped groove when the modular forming press plate is pressed to the bottom of the groove;

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

[0014] Compared with the prior art, the present application has the following advantages:

[0015] By means of the modular flexible forming structure, the conformal compaction device integrated with high-precision force sensing, and the motion control adaptive to the curvature of the workpiece, the rapid adaptation of the U-shaped groove size, the precise dynamic control of the forming pressure and the high-adhesion forming of the special-shaped surface are realized, so that the forming precision is ensured, the retooling efficiency and the automation level of process connection are greatly improved, and the problems of low forming precision, slow retooling, extensive pressure control, poor curvature adaptation and complicated process in the prior art are comprehensively solved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 It is a whole layout diagram of the composite material U-shaped flanging tool.

[0017] Fig. 2 It is a schematic diagram of a U-shaped flanging modular forming end structure.

[0018] Fig. 3 It is a schematic diagram of U-shaped flanging modular forming end motion. DETAILED DESCRIPTION

[0019] The present application will be further described below in combination with the drawings and specific embodiments.

[0020] In combination Figs. 1-3 , the present application provides a composite material U-shaped flanging tool and a forming method, and the core idea is: taking "movable leveling platform + collaborative robot + U-shaped flanging modular forming end + constant force sensing control + off-line process simulation" as an integrated architecture, high-precision automatic forming of a U-shaped groove is realized. Specifically, the composite material U-shaped flanging tool of the present application comprises a machine tool 1, a mobile trolley 2, a collaborative robot 3 and a U-shaped flanging end 4; the mobile trolley 2 is used to carry the collaborative robot 3, the collaborative robot 3 is integrated with the U-shaped flanging end 4 of "modular forming pressure plate + electric cylinder drive + constant force flange", the curvature adaptive track is planned in combination with the off-line programming system, the pressure dynamic adjustment and the side edge adhesion control are realized synchronously, and finally the U-shaped flanging requirements of different specifications of composite material components are met.

[0021] The machine tool 1 is a workbench of a filament laying device, and is used to fix a mold of a workpiece to be processed. During the processing, the mold is installed on the machine tool, and the collaborative robot is positioned beside it by the mobile trolley to process the U-shaped flanging of the workpiece.

[0022] The mobile trolley 2 is used to carry the collaborative robot 3 to the work position beside the workpiece. Its size is 2000x1200x650mm, and it is equipped with "two groups of universal wheels + two groups of directional wheels". The movement is controlled by the electric drive handrail (speed 0.5-1m / s). Four leveling legs are provided (leveling accuracy ±0.05°). When the load is 500KG, the maximum deformation is ≤0.6mm, which ensures the stability of the collaborative robot 3 operation;

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

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

[0025] The connecting flange is a mechanical interface between the end of the collaborative robot 3 and the U-shaped flanging end 4, which is directly connected to the end of the collaborative robot 3, and is used to install the entire U-shaped flanging end on the end of the robot. From the end of the collaborative robot, the connecting flange as a mechanical interface is connected in turn; below it is installed a constant force flange with high precision force perception and control function; the output end of the constant force flange is connected with a servo cylinder, which directly drives the lower modular forming press plate to perform compaction and lamination action; at the same time, the compression roller for pre-pressing materials is installed on the shell of the electric cylinder through the lateral support, and works cooperatively under the control of the constant force flange.

[0026] The modular forming press plate includes a fixed forming press plate 6-1 and a movable forming press plate 6-2, which are installed on an electric cylinder push rod driven mounting base to move vertically, the fixed forming press plate is rigidly installed on the base, and the movable forming press plate is installed on the base through a horizontal linear guide pair and can be driven by an independent horizontal small-sized air cylinder to slide horizontally relative to the base and the fixed press plate; both press plates are made of an aluminum alloy base material (lightweight, weight ≤1.5 kg), and the surface is covered with a 5 mm thick polyurethane buffer layer (Shore hardness 10A-75A adjustable, selected according to the type of composite material, such as 40A hardness for carbon fiber composite material) to avoid crushing the composite material; three types of press plate modules (adapted to the initial width of the U-shaped groove 52.8 mm, 60 mm and 70 mm) are provided, the pressure heads of the fixed forming press plate 6-1 and the movable forming press plate 6-2 are connected through quick-release buckles, the changeover time is less than 3 minutes, and the width of the U-shaped groove after laying is ≤38 mm; a chamfer with an angle of 15° to the horizontal plane is processed between the side edges and the bottom surface of the two press plates. When the movable forming press plate 6-2 is horizontally extended and the composite material layer is pressed against the side wall of the U-shaped groove, the 15° inclined surface can play a role of progressive guidance, reduce the shear force when the composite material is turned up, and reduce the risk of layer loss.

[0027] The electric cylinder 8 adopts a servo electric cylinder with a thrust of 1000N, which can accurately control the pressing depth of the modular forming press plate (accuracy ±0.02mm), and ensure that the modular forming press plate is in close contact with the bottom of the U-shaped groove;

[0028] The pressing roller 5 is arranged on one side of the modular forming press plate, adopts a φ20mm polyurethane roller, is provided with a return spring, and can realize adjustable pre-pressure 50-100N by adjusting the compression amount or stiffness of the spring, so as to fix the position of the composite material before forming and avoid layer displacement. The constant force flange is of HDAFC500-40 type, the maximum acting force is 500N, the stroke is 40mm, the force control accuracy is ±2N, and the built-in pressure sensor (sampling frequency 100Hz), displacement sensor and gyroscope attitude sensor are provided. The pressure and displacement sensors are used to monitor the forming pressure and pressing depth of the press plate in real time during the pressing process, so as to realize the coordinated control of pressure and position; the gyroscope attitude sensor can sense the curvature change of the workpiece surface in real time, and provide attitude adjustment feedback for the robot. The data of the three are cooperatively fused through the constant force flange, and together constitute an integrated adaptive control system of "force-position-attitude".

[0029] The control computer of the collaborative robot 3 is provided with a U-shaped flanging off-line programming and simulation system, which is developed based on the RoboDK platform, supports CAD model import (Creo / Catia / NX / SolidWorks), automatic generation of U-shaped groove track, curvature adaptive 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 profile of the U-shaped groove through the CAD model, extracts the key coordinates and normal vectors of the groove bottom and side wall, and then plans a continuous motion trajectory of the robot end effector "vertical down - translation along the side wall - safe exit", and ensures that the trajectory accuracy reaches ±0.05mm. Secondly, for the curvature change of the special-shaped body workpiece surface, the known workpiece CAD curvature information is used to generate the target posture, the actual posture is fed back through the gyroscope posture sensor and closed-loop correction is carried out, and at the same time the pressure sensor is combined for pressure closed-loop fine adjustment, both of which cooperate to realize the self-adaptation of the robot end posture to the complex surface, so that the forming press plate always maintains high adhesion (≥98%) with the groove wall during movement. Finally, before the trajectory is executed and in the simulation process, the system performs static and dynamic interference detection on the robot, end tool, workpiece and surrounding equipment based on the bounding box collision detection engine. If a collision risk is found, the motion path is automatically optimized or an obstacle avoidance point is inserted, and the detection accuracy reaches ±0.1mm, thereby ensuring the safety and reliability of the processing process.

[0031] The above tooling adopts a two-step process of U-shaped groove forming "groove bottom compaction - side edge adhesion", and the following control logic is designed:

[0032] 1. Groove bottom compaction stage:

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

[0034] The electric cylinder 8 drives the modular forming press plate to slowly press down (speed 0.5mm / s), and makes the fixed forming press plate adhere to the side wall of the U-shaped groove, and the compression roller 5 follows (only rotates) to avoid the composite material from wrinkling, and completes the tensioning of the composite material; The pressure sensor in the constant force flange monitors the end pressure of the modular forming press plate in real time by sensing the reaction force of the groove wall on the forming press plate, and when the pressure reaches 100-300N (adjusted according to the thickness of the layer, 200N is set for a 7.4mm layer), the electric cylinder 8 stops pressing down, and maintains the pressure for 3-5 seconds to ensure the compaction of the groove bottom.

[0035] 2. Side edge adhesion stage:

[0036] The small air cylinder drives the moving forming press plate 6-2 to translate along the side wall (speed 1mm / s), maintains the material laying of the U-shaped groove bottom, and tightly adheres the laying layer to the side wall, and performs pressure maintaining to the set time.

[0037] The air cylinder pressure feedback increases (detecting the contact of the modular forming press plate with the edge of the notch), it is determined that the side edge is attached, the air cylinder stops working, the robot drives the U-shaped flange end 4 out of the U-shaped groove, and in this process, the side edge of the modular forming press plate is always tightly attached to the side wall of the U-shaped groove.

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

[0039] 1. U-shaped groove trajectory automatic generation: after importing the workpiece numerical model, the system automatically identifies the U-shaped groove profile according to the CAD three-dimensional model of the workpiece, and obtains the coordinate information of the groove bottom and side wall from the workpiece numerical model, adjusts the spatial position of the collaborative robot 3 and the modular forming press plate, and vertically presses the modular forming press plate to the groove bottom. When the pressure sensor in the constant force flange detects that the pressure value borne by the modular forming press plate reaches the preset value, the pressure is maintained for 3-5 seconds; the fixed forming press plate 6-1 remains stationary, and the moving forming press plate 6-2 moves along the groove bottom. When the air cylinder pressure feedback increases to the set value, the contact force between the moving forming press plate 6-2 pressure head and the side wall of the U-shaped groove reaches the target value, and the modular forming press plates 6-1 and 6-2 are lifted and withdrawn after maintaining in this state for 3-5 seconds, generating the "pressing-translation-exit" motion trajectory of the modular forming press plate, with a trajectory accuracy of ±0.05mm;

[0040] 2. Curvature adaptive path planning: for the U-shaped groove of the special-shaped rotary barrel, in the offline programming stage, the CAD three-dimensional model of the workpiece is imported, and the system pre-calculates the ideal position and posture of each processing point on the side wall of the U-shaped groove, generating a theoretical motion trajectory that makes the press plate pressure head pressure surface (the side surface of the pressure head when the U-shaped groove side edge is laid, and the bottom surface of the pressure head when the U-shaped groove bottom edge is laid) always along its contact local curved surface normal. In the actual execution stage, the actual posture of the press plate is monitored in real time through the posture sensor on the constant force flange, and compared with the target posture of the corresponding point in the theoretical trajectory. The robot adjusts the wrist angle accordingly to ensure that the press plate is always aligned with the curved surface at the correct angle (pressing direction); the contact pressure between the press plate and the side wall is monitored in real time through the force sensor of the constant force flange. No matter whether the pressure deviates from the set value due to slight surface unevenness or movement error, the system will immediately control the robot or the constant force flange to adjust the position along the curved surface normal, so as to accurately maintain the pressure within the process requirement range, and ensure that the forming press plate is always attached to the groove wall (attachment degree ≥98%);

[0041] 3. Pressure parameter matching: According to the relevant data about the auxiliary material layer thickness, U-shaped groove size, and the pressure bearing of the forming pressure plate, and the movement speed of the electric cylinder in simulation and experiment, a corresponding process parameter machine learning model is formed. The model can output related process parameters such as forming pressure plate pressure (100-300N at the groove bottom, 200-500N at the side) and electric cylinder 8 movement speed according to the input composite material layer thickness (such as 7.4mm) and U-shaped groove size;

[0042] 4. Collision detection: Before trajectory execution and in the simulation process, the system performs static and dynamic interference detection on the robot, end tool, workpiece, and surrounding equipment based on the bounding box collision detection engine. If a collision risk is found, the motion path is automatically optimized or an obstacle avoidance point is inserted, and the detection accuracy is ±0.1mm, thereby ensuring the safety and reliability of the machining process.

[0043] The composite U-shaped flanging forming method of the application comprises the following steps:

[0044] Step S1: Workpiece positioning and tool preparation

[0045] Fix the mold of the composite material component to be machined (such as an aero-engine shell barrel mold) on the machine tool 1, move the tooling to the workpiece by the electric handrail of the moving trolley 2, adjust the supporting legs to make the horizontal error of the moving trolley 2 ≤0.1°;

[0046] According to the initial width of the U-shaped groove (such as 52.8mm), select the pressure head of the modular forming pressure plate that is suitable, install it through the quick-release buckle, and after the type change is completed, calibrate the relative position of the modular forming pressure plate and the end of the robot (calibration accuracy ±0.02mm);

[0047] Start the off-line programming system, import the workpiece model, set the layer thickness (7.4mm) and U-shaped 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-pressing

[0049] The collaborative robot 3 determines the spatial position according to the three-dimensional coordinates determined by the workpiece model and the coordinate system of the machine tool, drives the U-shaped flanging end 4 to move above the target U-shaped groove, and aligns the side of the fixed forming pressure plate 6-1 with the groove side wall (alignment error ≤±0.1mm);

[0050] The constant force flange 7 is started, the pressure roller 5 is controlled to press down to the surface of the composite material, an output of 80N pre-pressure is output, the position of the composite material is fixed, and displacement of the layer during subsequent forming is prevented.

[0051] Step S3: Groove bottom compaction

[0052] The servo cylinder 8 drives the modular forming press plate to move downward at a speed of 0.5 mm / s, and the 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 press plate contacts the groove bottom, the cylinder 8 stops moving, the constant force flange 7 maintains a pressure of 200 N for 5 seconds, and ensures that the groove bottom composite material is compacted (compaction degree ≥95%).

[0053] Step S4: Side edge fitting

[0054] The gyroscope attitude sensor and the pressure sensor detect the actual attitude and contact pressure of the press plate in real time and feed back to the collaborative robot 3; the collaborative robot 3 fine-tunes the position along the curved surface normal to make the side edge of the modular forming press plate fit the side wall of the U-shaped groove (fitting degree ≥98%);

[0055] The cylinder 8 drives the modular forming press plate to translate upward along the side wall at a speed of 1 mm / s, and the constant force flange 7 maintains the side edge pressure at 300 N; during the translation process, the compression roller 5 follows and continuously applies a pre-compression force of 80 N to avoid composite material wrinkles;

[0056] When the cylinder current rises to a set threshold (determining that the press plate leaves the edge of the U-shaped groove), the cylinder stops translating, and the side edge fitting is completed.

[0057] Step S5: Forming detection and resetting

[0058] The robot drives the end to exit the U-shaped groove, and an external laser profiler (accuracy ±0.01 mm) is used to detect the size of the U-shaped groove: height 40 mm (≥35.6 mm), width 37 mm (≤38 mm), and an external ultrasonic detector is used to detect the width of the layer loss area (55 mm≤60.8 mm);

[0059] If the detection is qualified, the robot drives the end to move to the next U-shaped groove, and repeats steps S2-S5; if it is not qualified, analyze the error causes (such as insufficient pressure, trajectory deviation), adjust the relevant parameters and re-form;

[0060] After all the U-shaped grooves are formed, the robot is reset, and the moving trolley is dragged to the standby position.

[0061] Example: Aviation engine shell barrel U-shaped flange forming

[0062] 1. Workpiece parameters

[0063] Workpiece type: aviation engine cylindrical shell barrel, material: carbon fiber reinforced resin matrix composite material (T800 / epoxy);

[0064] Size: barrel diameter 1500mm, length 2000mm, U-shaped groove number 8, initial width 52.8mm, target height 40mm (≥35.6mm), laying thickness 7.4mm;

[0065] Quality requirements: U-shaped groove width after laying ≤38mm, lost layer area width ≤60.8mm, compaction degree ≥95%, side edge fit degree ≥98%.

[0066] 2. Tooling configuration

[0067] Mobile trolley: leg leveling to 0.08°, load 500KG;

[0068] Collaborative robot: Lo stone CR35, working radius 2246mm, repeat positioning accuracy ±0.05mm;

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

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

[0071] Offline programming system: import shell barrel body model, automatically generate forming track of 8 U-shaped grooves, collision detection accuracy ±0.1mm.

[0072] 3. Processing process

[0073] Step 1: Fix the shell barrel body on the filament laying workbench, move the mobile trolley to the side of the barrel body, and level the legs; install a 52.8mm specification forming press plate and calibrate the end position (error 0.01mm);

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

[0075] Step 3: Move the end to the first U-shaped groove with the robot, calibrate the visual sensor (alignment error 0.08mm), and output 80N pre-pressure with the compression roller;

[0076] Step 4: Drive the press plate to press down at 0.5mm / s with the electric cylinder, monitor the pressure with the constant force flange, and maintain the pressure for 5 seconds after reaching 200N and detecting the groove bottom;

[0077] Step 5: Gyroscope feedback barrel curvature (radius 1500mm), robot adjusts posture, so that the side of the pressing plate fits the groove wall; the electric cylinder drives the pressing plate to move up at 1mm / s, the constant force flange maintains a pressure of 300N, and the compression roller follows;

[0078] Step 6: The electric cylinder current rises to the threshold value, and the upward movement stops; 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 grooves are completed, the robot resets 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 loss width 54mm≤60.8mm, compaction degree 96%≥95%, side fit degree 99%≥98%;

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

[0085] The prior art forming press plate is fixed in specification, and it takes a long time to change the type (≥2 hours), and the flexible buffer layer is easy to be crushed; the present application adopts a quick-release type modular press plate (change time <3 minutes), which is suitable for 52.8-70mm initial width U-shaped groove, and the surface is covered with a polyurethane buffer layer (hardness adjustable), which solves the problems of multi-specification adaptation and composite material protection, ensures that the U-shaped groove width after paving is ≤38mm, and the layer loss area is ≤60.8mm. The prior art uses single pressure forming, which cannot consider the groove bottom and side edge fitting quality; the present application cooperates with the servo cylinder through the constant force flange, and controls in stages: the groove bottom stage mainly controls the pressure (100-300N, precision ±2N), which ensures the compaction degree; the side edge stage combines position control (cylinder translation precision ±0.02mm) and curvature adaptation (robot posture adjustment ±0.05mm), which realizes the side edge fitting degree ≥98%, and breaks through the limitation of low forming precision of the prior art. The prior art cannot adapt to the curvature change of special-shaped workpieces, and the side edge fitting degree is low (≤85%); the present application uses the gyroscope posture sensor built in the constant force flange to feedback the workpiece curvature in real time, and the collaborative robot dynamically adjusts the end posture, so that the forming press plate always fits the groove wall, and even on the special-shaped barrel with a curvature radius of 1000-1700mm, the U-shaped groove size precision (height deviation ±0.3mm, width deviation ±0.2mm) can still be ensured. The present simulation software cannot generate the "down - translation - exit" track for the U-shaped groove, and cannot match the pressure parameters; the software of the present application can automatically extract the U-shaped groove profile to generate the forming track, match the pressure parameters according to the layer thickness and groove size, and the collision detection precision is ±0.1mm, the on-site debugging time is shortened from ≥2 hours to ≤20 minutes, and the problem of low efficiency of traditional programming is solved.

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 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. 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 of the pressure head and the bottom surface.

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 1, characterized in that, The mobile device 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 U-shaped flange end 4 out of the U-shaped groove for inspection of the formed workpiece.

Images