Multi-axis flexible bending machine numerical control system based on motion control card and control method thereof

Abstract

The application provides a multi-axis flexible bending machine numerical control system and control method based on a motion control card, which comprises control hardware and control software. The control hardware comprises an industrial computer, a motion control card, a driver and a feedback information element, an operating panel connected with a first connecting end of the industrial computer, a display screen connected with a second connecting end of the industrial computer, a first end of the driver connected with a third connecting end of the industrial computer through the motion control card, and a second end and a third end of the driver connected with a control end of a motor and the feedback information element respectively. The control software comprises a back-end logic layer, a front-end control layer and a communication layer for information interaction between the front-end and the back-end, and the back-end logic layer comprises a parameter configuration module, a file operation module, a manual module, a plate processing module, an auxiliary control module and a state display module. Compared with a general numerical control system, the bending forming precision is high, the function integration degree is high and the operation is stable, and the actual production needs are met.

Description

Technical Field

[0001] The present invention relates to the field of sheet metal processing machine tool numerical control systems, and in particular to a multi-axis flexible bending machine numerical control system based on a motion control card and a control method thereof. Background Art

[0002] Most CNC systems for flexible bending machines use commercial general-purpose CNC systems, which generally use equipment equipped with a motion control module (PLC) to control the machine tool axis motion. When using PLC equipment for machine tool control, the control system must be developed based on the development framework pre-integrated by the corresponding PLC manufacturer, which limits the control system's functional capabilities. Furthermore, the programming languages ​​of different PLC manufacturers are not interoperable, and after changing PLC brands, the original CNC system cannot be adapted. The number of available axes of a machine tool controlled by a PLC-based CNC system is directly limited by the PLC model selected during initial development, resulting in poor scalability. Changing the number of axes controlled by a machine tool requires a complete redesign of the CNC system.

[0003] Most general-purpose CNC systems are developed based on templates, and their control functions are all the same. They cannot adapt well to the mechanical structure characteristics and functional requirements of different multi-axis flexible bending machines. During use, there are problems such as the inability to realize the offset clamping processing function of special-shaped plates, low operating accuracy of the plate clamping mechanism, cumbersome input of bending processing parameters, and cumbersome machine tool adjustment and adaptation system processes. The system has poor human-computer interaction and the learning cost for operators to use the equipment is high. At the same time, the general-purpose CNC system is not convenient and cannot meet the actual production use needs. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a multi-axis flexible bending machine CNC system and control method based on a motion control card. By adopting the dual CPU control mode of "industrial computer + motion control card", Ethernet control automation technology EtherCAT is used to realize real-time communication between the industrial computer and the motion control card, and between the motion control card and the driver. A bus structure is selected as the networking topology to meet the requirements of the industrial control industry for shorter data updates, low communication jitter during data synchronization, and low hardware cost. At the same time, the secondary positioning function and plate bending rebound compensation are integrated into the CNC system. During processing, only the required angle needs to be entered in the program, and the program automatically calculates and obtains the actual processing angle, thereby simplifying the bending processing operation process.

[0005] The present invention provides a multi-axis flexible bending machine numerical control system based on a motion control card, which includes control hardware and control software, and is characterized in that the control hardware includes an industrial computer, an operation panel, a display screen, a motor, a motion control card, a driver and a feedback information element, the operation panel is connected to the first connection end of the industrial computer through an input module, the display screen is connected to the second connection end of the industrial computer through an output module, the first end of the driver is connected to the first end of the motion control card through a Category 6 network cable, the second end and the third end of the driver are respectively connected to the control end of the motor and the feedback information element, the second end of the motion control card is connected to the third connection end of the industrial computer through a Category 6 network cable, and two adjacent drivers are connected to each other through the Category 6 network cable, thereby forming a bus topology structure; the control software adopts a hierarchical design, which includes a back-end logic layer, a front-end control layer and a communication layer for front-end and back-end information interaction, the front-end control layer includes a motion control module, an IO output control module and an IO input detection module, and the motion control module transmits information according to the communication layer for front-end and back-end information interaction. Motion logic, obtains different motion forms, the IO output control module outputs different control forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction, the IO input detection module outputs different operation forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction, the back-end logic layer includes a parameter configuration module, a file operation module, a manual module, a plate processing module, an auxiliary control module and a status display module; the parameter configuration module includes hardware parameter configuration, axis motion parameter configuration and assembly error parameter configuration, the file operation module is used to process the CNC program for plate bending processing; the CNC program includes processing technology, processing length and processing angle; the manual module includes single-axis free manual control, return to zero, press release, loading preparation and plate fixing; the single-axis free manual control includes inching control mode, fixed position movement control mode and fixed distance movement control mode; the plate processing module includes bending process, edge pressing process, edge changing process, feeding mechanism control, fixing mechanism control and edge changing mechanism control; the auxiliary control module includes reset, return to zero and ratio adjustment.

[0006] Preferably, the communication layer for front-end and back-end information interaction realizes real-time communication through the EtherCAT protocol, which can meet the requirements of the industrial control industry for relatively short data updates and low communication jitter during data synchronization.

[0007] Preferably, the control hardware adopts a dual CPU bus hardware architecture in a "PC+motion control card" mode.

[0008] Preferably, the inching control mode includes 0.01 mm inching distance selection or continuous inching mode selection, 0.1 mm inching distance selection or continuous inching mode selection, and 1 mm inching distance selection or continuous inching mode selection.

[0009] Preferably, the back-end logic layer further includes a secondary positioning process suitable for processing of offset clamping of profiled plates and a function library for realizing accurate springback compensation of plate bending processing.

[0010] In another aspect of the present application, a control method of a multi-axis flexible bending machine numerical control system based on the aforementioned motion control card is provided, which includes the following steps:

[0011] S1, zero point setting of relevant motion mechanisms in the bending machine:

[0012] S11, installing the control hardware and the control software on the machine tool respectively, and ensuring that the driver of the configured axis is not enabled to the motor, setting the current position of the driver as the zero point;

[0013] S12, measuring the offset distance between the current position of the configured axis and the specified processing zero point by using relevant measuring tools, inputting the offset distance value into the numerical control system, and correcting the position of the processing zero point;

[0014] S13, after each power-off restart, first ensuring that the driver of the configured axis is not enabled to the motor, obtaining the offset distance value recorded in the numerical control system and the current pulse position of the driver of the configured axis, calculating the pulse position of the current position in the machine tool coordinate system, and setting the current position of the driver of the configured axis as the corresponding position;

[0015] S14, enabling the motor of the driver of the configured axis, so as to normally start the equipment;

[0016] S2, inputting the plate size and the clamping size of the plate into the numerical control system of the bending machine, and moving the bending machine control fixed mechanism and the plate loading positioning mechanism to the clamping position;

[0017] S3, mounting the plate on the fixed mechanism with a crank slider, and obtaining the initial assembly angle error α' and the initial assembly distance error l' in the assembly error parameter configuration in the numerical control system of the bending machine, as the position control function of the P-axis motion of the bending machine, accurately controlling the motion of the fixed mechanism through the crank slider, and the expression of the motion function of the crank slider is as follows:

[0018]

[0019] Wherein, α is the included angle between the upper crank and the vertical surface, l is the distance from the lower surface of the pressing block to the upper surface of the rotating disc, r1 and r2 are the lengths of the upper crank and the lower crank of the crank slider mechanism respectively, and the expression between the included angle and the distance is:

[0020]

[0021] By precisely controlling the movement of the crank slider fixing mechanism, the precise control of the clamping force can be realized, so as to effectively relieve the relative movement between the plate and the fixing mechanism caused by inertia when the plate rotates and moves horizontally after being fixed, and better positioning accuracy is realized.

[0022] S4, the feeding mechanism in the bending machine drives the plate to move towards the direction of the pressure knife until the front edge of the plate is flush with the front edge of the processing table, and is in a processing state;

[0023] S5, according to the processing length of the plate, the feeding mechanism drives the plate to move to the corresponding distance in the direction of the pressure knife, at this time the pressure knife presses and fixes the plate, and the processing punch moves to a reasonable position according to the processing path, so that the plate is bent and formed;

[0024] S6, according to the processing mode and clamping mode of the plate, different operation modes are selected:

[0025] If the plate is normally clamped for forming processing, the specific implementation steps are as follows:

[0026] If the plate processing is completed, the processing punch and the pressure knife are sequentially retreated to the zero position, the feeding mechanism is retreated to the plate loading position, the fixing mechanism is loosened, and the plate processing is completed; if the plate processing is not completed, and the processing is still the current edge, the processing punch and the pressure knife are sequentially retreated to the processing position, and step S5 is continued; if the plate processing is not completed, and the processing is the other edge, the processing punch and the pressure knife are sequentially retreated to the zero position, the feeding mechanism is retreated to the plate loading position, and the edge changing mechanism rotates the plate to the corresponding processing edge, and step S4 is continued;

[0027] If the plate is normally clamped for forming processing, the specific implementation steps are as follows:

[0028] If the plate processing is completed, the processing punch and the pressure knife are sequentially retreated to the zero position, the feeding mechanism is retreated to the plate loading position, the fixing mechanism is loosened, and the plate processing is completed; if the plate processing is not completed, and the processing is still the current edge, the processing punch and the pressure knife are sequentially retreated to the processing position, and step S5 is continued; if the plate processing is not completed, and the processing is the other edge, the processing punch and the pressure knife are sequentially retreated to the zero position, the feeding mechanism is retreated to the plate loading position, and the edge changing mechanism rotates the plate to the corresponding processing edge, and step S4 is continued;

[0029] If the plate is normally clamped for forming processing, the specific implementation steps are as follows:

[0030] If the plate processing is completed, the processing punch and the pressing knife will return to the zero position in sequence, the feeding mechanism will return to the upper plate position, the fixing mechanism will release the plate, and the processing will be completed; if the plate processing is not completed, and the processing is still the current side, the processing punch and the pressing knife will return to the waiting position in sequence, and continue with step S5; if the plate processing is not completed, and the processing is the relative side, the processing punch will return to the zero point, the pressing knife will not be released, the fixing mechanism will be released, and according to the plate size and offset clamping distance, the straight line at the midpoint of the plate perpendicular to the processing direction is used as the symmetry axis to calculate the symmetric position of the current clamping position, the CNC system of the bending machine will move the fixing mechanism to this position, the fixing mechanism will fix the plate, the pressing knife will be released, the feeding mechanism will return to the upper plate position, the side changing mechanism will rotate the plate to the corresponding processing side, and continue with step S4.

[0031] Preferably, the step S12 specifically includes the following steps:

[0032] S121, the IO output control module operates the machine tool gas circuit equipment to raise the positioning mechanism;

[0033] S122. Use a tape measure to measure the minimum distance between the edge of the positioning mechanism and the processing zero point;

[0034] S123. Record the minimum distance information through the axis motion parameter configuration function.

[0035] Preferably, the step S13 specifically includes the following steps:

[0036] S131. The CNC system of the bending machine obtains the offset distance value. Based on the conversion relationship between the current pulse position distance and pulse value of the configured axis driver, the specific expression for converting the offset distance value into the offset pulse value is as follows:

[0037]

[0038] S132, the bending machine CNC system automatically obtains the current pulse position reading of the configuration axis driver through the PDO instruction, and at the same time obtains the expression of the corresponding position pulse value of the current position of the configuration axis driver in the configuration axis processing coordinate system as follows:

[0039] After the coordinate system is transformed, the corresponding position pulse = current position pulse + offset pulse;

[0040] S133, the bending machine CNC system sets the current position of the driver to the corresponding position pulse value through the PDO instruction.

[0041] Preferably, the steps for solving the relationship between the initial angle and the final angle of the bending process are as follows:

[0042] S1. Determine the motion path of the punch during sheet metal forming within the available processing area of ​​the machine tool, and select a test bending point for the sheet metal on the motion path;

[0043] S2. Select plates of different materials and thicknesses, simulate the plate bending process through the manual mode of the CNC system, select the plate bending test point as the processing end point, repeatedly test the plate and measure the test bending results;

[0044] S3. Fitting the relationship between the initial angle and the final angle of the bending process under different material and plate thickness conditions to obtain the relationship function under these conditions;

[0045] S4. Integrate all functional relationships with material and plate thickness conditions to obtain a relational function library.

[0046] Preferably, the fitting function includes an exponential function, a linear function, a quadratic function, and a cubic function.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] 1. The control hardware networking of the present invention is simple and convenient, and has good compatibility and scalability.

[0049] 2. The control software of the present invention has good openness, a higher degree of customization, friendly human-computer interaction, high functional integration, and stable operation, meeting actual production needs.

[0050] 3. The present invention can automatically realize bending compensation and processing action connection, automatically identify and process action interference during the processing, reduce the difficulty of system operation, and low the learning cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1a-Figure 1b This is a structural diagram of a ten-axis flexible bending machine of a multi-axis flexible bending machine numerical control system based on a motion control card of the present invention;

[0052] Figure 2 This is a block diagram of the connection mode of the multi-axis flexible bending machine CNC system based on the motion control card of the present invention;

[0053] Figure 3 This is a connection topology diagram of the multi-axis flexible bending machine CNC system based on the motion control card of the present invention;

[0054] Figure 4 This is a functional module composition diagram of the multi-axis flexible bending machine CNC system based on the motion control card of the present invention;

[0055] Figure 5 This is the hardware architecture motion control logic diagram of the multi-axis flexible bending machine CNC system based on the motion control card of the present invention;

[0056] Figure 6This is a bending control logic diagram in the control method of the multi-axis flexible bending machine numerical control system based on the motion control card of the present invention;

[0057] Figure 7 This is a motion principle diagram of the plate fixing mechanism in the control method of the multi-axis flexible bending machine numerical control system based on the motion control card of the present invention;

[0058] Figure 8 This is a schematic diagram of the secondary positioning and initial clamping in the control method of the multi-axis flexible bending machine CNC system based on the motion control card of the present invention.

[0059] Main reference numerals:

[0060] Feeding mechanism 1, edge changing mechanism 2, pressing knife 3, plate loading and positioning mechanism 4, fixing mechanism 5, fixing mechanism driving motor 6, processing punch 7, upper crank 8, lower crank 9, pressing block 10, plate 11, turntable 12, front edge of processing table 13, formed plate 14. DETAILED DESCRIPTION

[0061] To fully describe the technical content, structural features, objectives and effects of the present invention, the following is a detailed description with reference to the accompanying drawings.

[0062] Multi-axis flexible bending machine CNC system based on motion control card, such as Figure 4 As shown, the control hardware and control software are included. The control hardware utilizes a dual-CPU bus hardware architecture based on a "PC + motion control card" model. This architecture disperses system functions, effectively reducing the CPU's workload and increasing its processing speed. The hardware includes an operation panel or display screen connected to the industrial computer, along with motors, motion control cards, drivers, and feedback information components. The motion control card and drivers are housed in an electrical cabinet, leaving the industrial computer exposed to the factory production environment. The industrial computer independently performs non-real-time functions such as parameter adjustment, processing instructions, motion path planning, and human-computer interaction. The motion control card handles real-time control functions such as precise position control of each motor, motion mode control, and origin limit detection.

[0063] like Figure 2 and Figure 3As shown, the operation panel is connected to the first connection end of the industrial computer through the input module, the display screen is connected to the second connection end of the industrial computer through the output module, the first end of the driver is connected to the first end of the motion control card through a Category 6a network cable, the second end and the third end of the driver are connected to the control end and the feedback information element of the motor respectively, and the second end of the motion control card is connected to the third connection end of the industrial computer through a Category 6a network cable with a shielded hose, thereby realizing real-time data two-way interaction and effectively coping with communication disturbances in the production site. Two adjacent drivers are connected to each other through the Category 6a network cable, forming a connection mode similar to a series connection, thereby forming a bus topology structure with easy wiring, small cable consumption, high reliability, easy expansion and easy installation.

[0064] Specifically, the number of driver-motor servo control groups can be expanded infinitely according to actual needs. The motion control card can be used normally as long as the maximum number of controllable axes exceeds the required number of driver-motor servo control groups, and has good hardware compatibility.

[0065] Based on the control hardware and bending processing requirements, a control software solution for the CNC system of a multi-axis flexible bending machine is designed. The CNC system includes modules such as parameter configuration, file operation, and plate processing to realize functions such as parameter configuration, communication status detection, and alarm display. The control software solution of the CNC system is directly oriented to the underlying logic of the hardware equipment, and can easily realize function adjustment and expansion according to actual needs.

[0066] like Figure 4 As shown in the figure, the control software adopts a layered design, including the back-end logic layer implemented by the industrial computer, the front-end control layer implemented by the motion control card, and the communication layer for front-end and back-end information interaction. The front-end control layer includes the motion control module, IO output control module, and IO input detection module. Figure 5 As shown in the figure, the motion control module obtains different motion forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction. For example, the motion control function realizes the sequential start and stop, synchronous motion, gantry motion and interpolation motion of each servo control group according to the motion mode logic transmitted by the communication layer, the accurate positioning of the end position of each axis motion, and the precise control of the speed and acceleration of each axis motion. There is a transmission ratio between the servo motor and the machine tool motion axis. The electronic gear ratio set by the driver obtains the pulse required for a single turn of the motor, thereby realizing the functional correspondence between the mechanical position and the pulse value. The specific expression is as follows:

[0067]

[0068] The industrial computer calculates the movement distance based on the target position and current position, converts the distance into a pulse value, and sends the action control information to the motion control card. The motion control card sends corresponding pulses to the driver based on this information, causing the motor to move and drive the machine tool axis to move.

[0069] The IO output control module outputs different control forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction. For example, the IO output control function realizes the color switching of the machine tool signal indicator light, servo motor brake control and machine tool air system control according to actual needs; the IO input detection module outputs different operation forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction. For example, the IO input detection function is used to receive hardware alarm information and button station input operation information.

[0070] The back-end logic layer includes a parameter configuration module, a file operation module, a manual module, a plate processing module, an auxiliary control module and a status display module. Preferably, the back-end logic layer also includes a secondary positioning process suitable for offset clamping processing of special-shaped plates and a function library for realizing accurate springback compensation for plate bending processing.

[0071] The communication layer, which facilitates front-end and back-end information exchange, transmits motion-mode and other logic processed by the back-end logic layer to the front-end control layer. It also transmits I / O input signals received by the front-end control layer to the back-end logic layer for processing. The communication layer operates in real-time and includes a communication status detection function.

[0072] Specifically, the communication layer for front-end and back-end information interaction achieves real-time communication through the EtherCAT protocol, which can meet the industrial control industry's requirements for shorter data updates, low communication jitter during data synchronization, and low hardware costs.

[0073] The parameter configuration module includes hardware parameter configuration, axis motion parameter configuration, and assembly error parameter configuration. The motion control card loses some configuration information after powering off. Hardware parameter configuration automatically reconfigures this information to the motion control card upon powering on. Various errors are inevitable during the production and assembly process of a machining center. Assembly error parameter configuration records these errors and compensates for them when generating motion distances, thereby improving machining accuracy. Axis motion parameter configuration includes information such as transmission ratio, backlash, operating speed, acceleration, limit switches, and zero offset, which serve as reference information when generating the motion logic for each axis.

[0074] Specifically, the zero offset information is the offset between the machine tool's machining zero point and the drive's zero point. By setting this offset, the drive coordinate system can be transformed into the machine tool's machining coordinate system, eliminating the need to align the machine tool's initial installation position with the machine tool's machining zero point. This simplifies the initial adjustment of the CNC system after machine tool installation.

[0075] The file operation module is used for processing the numerical control program of the plate bending processing, the numerical control program is given in the form of a table, and operations can be performed in the table, including processing technology, processing length and processing angle, the numerical control program can be saved, modified and deleted, and repeated use of the numerical control program is realized. The existing numerical control program in the numerical control system is displayed in a tree structure beside the numerical control program editing table, so that the operation of the existing numerical control program is facilitated. When the plate 11 is processed, the current executed numerical control program row is automatically highlighted, and corresponding parameters are obtained according to the corresponding positions in the editing table to generate a motion mode logic.

[0076] The manual module includes single-axis free manual control, zero reset, knife 3 release, loading preparation and plate 11 fixation, single-axis free manual control includes inching control mode, fixed position movement control mode and fixed distance movement control mode to meet different needs; inching control mode includes 0.01mm inch distance selection or continuous inching mode selection, 0.1mm inch distance selection or continuous inching mode selection and 1mm inch distance selection or continuous inching mode selection.

[0077] The plate processing module is designed and realized to control the upper bending, lower bending, upper edge pressing and lower edge pressing processing technology participated by the bending punch and the knife 3, and to control the plate fixation, edge changing and secondary positioning processing technology participated by the feeding mechanism 1, the fixation mechanism 5 and the edge changing mechanism 2, including bending technology, edge pressing technology, edge changing technology, feeding mechanism 1 control, fixation mechanism 5 control and edge changing mechanism 2 control, auxiliary control module, including reset, zero reset and magnification adjustment.

[0078] In the second aspect of the present application, the control method of the multi-axis flexible bending machine numerical control system based on the motion control card is mainly realized as follows:

[0079] Firstly, the width, length and thickness of the plate 11 are input through the operation panel and the input module, and the material of the plate 11 is selected.

[0080] Secondly, the processing program conforming to the specification is written through the operation panel and the input module. The processing program only contains bending forming processing instructions, without auxiliary action instructions. The processing program format contains forming technology and forming size parameters (such as length and angle). The processing program should be written as much as possible to complete the processing of the same side at one time, and the processing forming shapes are processed in sequence, and there is no processing interference between the processing forming shapes.

[0081] The third step involves manually loading the material and starting the machining center to begin processing. During the machining process, the industrial computer recognizes the machining program and automatically generates the complete machining motion. It then sends motion command information to the motion control card and receives feedback from the card. Based on the interactive information from the industrial computer, the card generates pulses to drive the motor, accurately executing various motion types, including sequential start-stop, interpolation, and synchronization. The card also uses feedback from the absolute encoder to obtain the servo motor's current position in real time.

[0082] The fourth step is to manually remove the workpiece after processing is completed. The CNC system of the flexible bending processing center can accurately control the movement of the flexible bending machine to achieve sheet metal bending and forming processing. The processing accuracy meets the sheet metal industry standard GB / T 33644-2017.

[0083] In a preferred embodiment of the present invention, a control method for a multi-axis flexible bending machine numerical control system based on a motion control card specifically includes the following steps:

[0084] S1. Zero point setting of related motion mechanisms in the bending machine.

[0085] S11. Install the control hardware and control software on the machine tool respectively. When the machine tool is initially installed, ensure that the driver of the configured axis does not enable the motor and set the current position of the driver to zero.

[0086] S12. When the machine tool is initially installed, use a vernier caliper or feeler gauge or other related measuring tools to measure the offset distance between the current position of the configuration axis and the specified processing zero point, and input the offset distance value into the CNC system, while correcting the position of the processing zero point.

[0087] S121. The IO output control module operates the machine tool gas circuit equipment to raise the positioning mechanism.

[0088] S122. Use a tape measure to measure the minimum distance between the edge of the positioning mechanism and the machining zero point.

[0089] S123. Record the minimum distance information through the axis motion parameter configuration function.

[0090] S13. After each power-off and restart, first ensure that the driver of the configured axis does not enable the motor, obtain the offset distance value recorded in the CNC system and the current pulse position of the configured axis driver, calculate the pulse position of the current position in the machine tool coordinate system, and set the current position of the configured axis driver to the corresponding position.

[0091] S131. The CNC system of the bending machine obtains the offset distance value. Based on the conversion relationship between the current pulse position distance and pulse value of the configured axis driver, the specific expression for converting the offset distance value into the offset pulse value is as follows:

[0092]

[0093] S132, the bending machine CNC system automatically obtains the current pulse position reading of the configuration axis driver through the PDO instruction, and at the same time obtains the expression of the corresponding position pulse value of the current position of the configuration axis driver in the configuration axis machining coordinate system as follows:

[0094] After the coordinate system is transformed, the corresponding position pulse = current position pulse + offset pulse.

[0095] S133, the bending machine CNC system sets the current position of the driver to the corresponding position pulse value through the PDO instruction.

[0096] S14. The driver of the configured axis enables the motor, thereby starting the equipment normally.

[0097] Specifically, steps S11 and S12 require the participation of debugging personnel, and steps S13 and S14 are system built-in logic.

[0098] S2. The size of the plate 11 and the clamping size of the plate 11 are input into the numerical control system of the bending machine, and the bending machine controls the fixing mechanism 5 and the plate loading and positioning mechanism 4 to move to the clamping position.

[0099] S3, the plate 11 is fixed on the fixing mechanism 5 having a crank slider, and the crank slider equation is introduced to accurately control the movement of the fixing mechanism 5; Figure 7 As shown, when the plate 11 needs to be pressed, the fixing mechanism in the ten-axis flexible bending machine drives the motor 6 to rotate clockwise, drives the upper crank 8 to move clockwise, and presses the pressure block 10 downward to fix the plate 11; when the plate 11 needs to be loosened, the fixing mechanism in the ten-axis flexible bending machine drives the motor 6 to rotate counterclockwise, drives the upper crank 8 to move counterclockwise, and lifts the pressure block 10. The angle between the upper crank 8 and the vertical plane is denoted as α, and the distance from the lower surface of the pressure block 10 to the upper surface of the turntable 12 is denoted as l. According to the actual measured highest point (the upper crank 8 coincides with the lower crank 9) and the lowest point (the pressure block 10 is in contact with the turntable 12) angle and distance, the crank slider motion function is constructed, and the specific expression is as follows:

[0100]

[0101] Wherein, α is the angle between the upper crank 8 and the vertical plane, l is the distance from the lower surface of the pressure block 10 to the upper surface of the turntable 12, r1 and r2 are the lengths of the upper crank 8 and the lower crank 9 of the crank slider mechanism respectively, and the expression between the angle and the distance is:

[0102]

[0103] In this function, the initial assembly angle error α′ is introduced, replacing α with (α+α′); the initial assembly distance error l′ is introduced, replacing l with (l+l′). The crank slider motion function is entered into the CNC system of the bending machine as the P-axis motion position control function. When the P-axis motion needs to be controlled, the target position angle value is obtained from the revised formula. The difference between the target angle value and the current angle value is calculated to achieve accurate positioning of the crank slider motion. In addition, with the help of the revised formula, the current P-axis position can be intuitively displayed in real time.

[0104] S4. Use the feeding mechanism 1 in the bending machine to drive the plate to move in the direction of the pressing knife 3 until the front edge of the plate 11 is flush with the front edge 13 of the processing table and is in a state to be processed.

[0105] S5. According to the processing length of the plate 11, the feeding mechanism 1 drives the plate 11 to move to the corresponding distance in the direction of the pressing knife 3. At this time, the pressing knife 3 presses down and fixes the plate 11, and the processing punch 7 moves to a reasonable position according to the processing path to bend the plate 11 into shape.

[0106] S6. Select different operation modes according to the processing and clamping methods of the plate 11:

[0107] If the forming process of the plate 11 is normal clamping, continue to use the normal processing method, and the specific implementation steps are as follows:

[0108] If the processing of the plate 11 is completed, the processing punch 7 and the pressing knife 3 will retreat to the zero position in sequence, the feeding mechanism 1 will retreat to the upper plate position, the fixing mechanism 5 will release the plate 11, and the processing will be completed; if the processing of the plate 11 is not completed, and the processing is still for the current side, the processing punch 7 and the pressing knife 3 will retreat to the position to be processed in sequence, and continue with step S5; if the processing of the plate 11 is not completed, and other sides need to be processed, the processing punch 7 and the pressing knife 3 will retreat to the zero position in sequence, the feeding mechanism 1 will retreat to the upper plate position, and at the same time the side changing mechanism 2 will rotate the plate 11 to the corresponding processing side, and continue with step S4.

[0109] When processing conventional sheet metal, the processing can be completed by clamping and fixing it in the center. When processing special-shaped sheet metal, it may not be possible to clamp it in the center, or due to special production needs, the special-shaped sheet metal needs to be clamped a certain distance away from the center. In this case, a processing method with secondary positioning is required.

[0110] If the special-shaped sheet metal forming process is to process adjacent edges with offsets, and there is no significant change in the special-shaped sheet metal processing process, it is only necessary to modify the distance calculation logic from the front edge of the special-shaped sheet metal to the front edge of the processing table after the sheet metal edge is changed. The specific implementation steps are as follows:

[0111] If the processing of the plate 11 is completed, the processing punch 7 and the pressing knife 3 will retreat to the zero position in sequence, the feeding mechanism 1 will retreat to the upper plate position, the fixing mechanism 5 will release the plate 11, and the processing will be completed; if the processing of the plate 11 is not completed, and the processing is still the current side, the processing punch 7 and the pressing knife 3 will retreat to the waiting position in sequence, and continue with step S5; if the processing of the plate 11 is not completed, and the processing is the adjacent side, the processing punch 7 and the pressing knife 3 will retreat to the zero position in sequence, the feeding mechanism 1 will retreat to the upper plate position, and at the same time the side changing mechanism 2 will rotate the plate 11 to the corresponding processing side, and continue with step S4.

[0112] If the plate 11 is formed into opposite edges with offsets, the specific implementation steps are as follows:

[0113] If the processing of the plate 11 is completed, the processing punch 7 and the pressing knife 3 will retreat to the zero position in sequence, the feeding mechanism 1 will retreat to the upper plate position, and the fixing mechanism 5 will release the plate 11 to complete the processing; if the processing of the plate 11 is not completed, and the processing is still the current side, the processing punch 7 and the pressing knife 3 will retreat to the waiting position in sequence, and continue with step S5; if the processing of the plate 11 is not completed, and the processing is the relative side, the processing punch 7 will retreat to the zero point, the pressing knife 3 will not be released, and the fixing mechanism 5 will be released. According to the size of the plate 11 and the offset clamping distance, the straight line at the midpoint of the plate 11 perpendicular to the processing direction is used as the symmetry axis to calculate the symmetric position of the current clamping position. The CNC system of the bending machine will move the fixing mechanism 5 for secondary positioning and move to this position. The fixing mechanism 5 fixes the plate 11, the pressing knife 3 is released, the feeding mechanism 1 retreats to the upper plate position, and the edge changing mechanism 2 rotates the plate 11 to the corresponding processing side, and continue with step S4.

[0114] Furthermore, to improve bending efficiency and simplify the bending process, the CNC system can automatically and accurately compensate for bending springback. This eliminates the need for additional testing and input of compensation angles when programming the CNC program for sheet metal bending, simplifying the programming workload. Currently, the sheet metal processing industry mostly uses an overbending method for sheet metal bending. This involves bending the sheet metal at an angle greater than the desired angle. After the force is released and the sheet metal rebounds, the accurate bending angle is achieved.

[0115] A bending process that considers springback and is based on experimental data fit, generates a function library for the relationship between the initial and final bending angles. This library is then integrated into the CNC system of the press brake, enabling accurate springback compensation in sheet metal bending. Given the desired sheet material and thickness, the final forming angle is related to the final position of the process.

[0116] The specific implementation steps are as follows:

[0117] S1. Within the available processing area of ​​the machine tool, determine the motion path of the punch 7 when the sheet 11 is processed and formed, and select the bending test point of the sheet 11 on the motion path.

[0118] S2. Select plates of different materials and thicknesses respectively, simulate the plate 11 bending process through the manual mode of the CNC system, select the plate 11 bending test point as the processing end point, repeatedly put the plate on trial bending and measure the test bending results.

[0119] S3. Under the premise of taking into account accuracy and avoiding overfitting, the relationship between the initial angle and the final angle of the bending process under different materials and plate thickness conditions is fitted to obtain the relationship function under this condition.

[0120] Specifically, the fitting functions include exponential functions, linear functions, quadratic functions and cubic functions.

[0121] S4. Integrate all functional relationships with material and plate thickness conditions to obtain a relational function library.

[0122] Specifically, during bending processing, for plate processing under the conditions of materials and plate thicknesses already in the function library, compensation data can be directly obtained from the function library; for plate processing of other material thicknesses of materials already in the function library, it can be obtained by interpolation of two sets of function relationships; for plate processing for which data does not exist in the function library, the compensation value can be entered into the compensation value input interface reserved by the system to realize processing.

[0123] The following is a further description of a multi-axis flexible bending machine numerical control system and control method based on a motion control card of the present invention in conjunction with an embodiment:

[0124] Ten-axis flexible bending machine with multi-axis flexible bending machine CNC system based on motion control card is used for flexible bending processing of sheet metal. Figure 1a-Figure 1b As shown, the ten-axis flexible bending machine has seven degrees of freedom and is driven by a total of ten motors: one motor for driving the feeding mechanism 1, one motor for driving the edge changing mechanism 2, two motors for driving the pressing knife 3, one motor for driving the plate loading and positioning mechanism 4, one motor for driving the fixing mechanism 5 and four motors for driving the processing punch 7.

[0125] The feeding mechanism 1 is driven by a single motor, which is connected to the input end of the feeding mechanism 1 via a lead screw. The feeding mechanism 1 moves horizontally, and the direction of movement is recorded as the Y axis of the machine tool. The first mounting end and the second mounting end of the feeding mechanism 1 are connected to the side-changing mechanism 2 and the fixing mechanism 5 respectively. The side-changing mechanism 2 is driven by a single motor, which is connected to the input end of the side-changing mechanism 2 via a planetary reducer. The side-changing mechanism 2 rotates, and the direction of movement is recorded as the C axis of the machine tool; the press cutter 3 is driven by two motors, and the two motors constitute a gantry drive. The two motors The machine is connected to the input end of the press tool 3 through a planetary reducer. The press tool 3 moves vertically, and the movement direction is recorded as the Z axis of the machine tool. The plate loading and positioning mechanism 4 is driven by a single motor. The motor is connected to the input end of the plate loading and positioning mechanism 4 through a conveyor belt and a screw. The plate loading and positioning mechanism 4 moves horizontally, and the movement direction is recorded as the X axis of the machine tool. There are three cylindrical pins mechanically connected to the plate loading and positioning mechanism 4. The cylindrical pins are used to achieve limitation in the length and width directions when the plate is loaded. The lifting and lowering of the cylindrical pins are controlled by the machine tool air pump.

[0126] The fixing mechanism 5 is driven by a single motor. The fixing mechanism driving motor 6 is connected to the input end of the fixing mechanism 5 via a crank slider mechanism. The fixing mechanism 5 moves vertically, and the movement direction is recorded as the P axis of the machine tool. The processing punch 7 is driven by two sets of gantry motors to achieve movement in two degrees of freedom. The four motors are connected to the input end of the processing punch 7 via planetary reducers. The horizontal and vertical movement directions are recorded as the V axis and W axis of the machine tool respectively. The positive direction of each axis of the machine tool is as follows: Figure 1a and Figure 1b Indicated by the arrow direction.

[0127] The specific connection method of the dual CPU bus hardware architecture using the "PC + motion control card" mode in the ten-axis flexible bending machine is as follows Figure 2 As shown, since the ten-axis flexible bending machine has a total of ten motors, ten sets of driver-servo motor servo control groups are set up, and the maximum number of controllable configuration axes of the motion control card is twelve.

[0128] like Figure 6 As shown in the figure, the control method of the multi-axis flexible bending machine numerical control system based on the motion control card of the present invention is implemented in the ten-axis flexible bending machine as follows:

[0129] S1. Since the ten-axis flexible bending machine has two driving modes: single-axis drive and gantry drive, the zero point setting of the relevant motion mechanism in the ten-axis flexible bending machine is divided into two cases.

[0130] The zero point setting of the single-axis driven plate feeding and positioning mechanism 4 in the ten-axis flexible bending machine is due to the interference of the mechanical structure in the ten-axis flexible bending machine. The initial installation position of the mechanism can never coincide with the machine tool processing zero point position. For the single-motor driven plate feeding and positioning mechanism 4 in the ten-axis flexible bending machine, the adjustment process is as follows:

[0131] S11. Install the control hardware and control software on the ten-axis flexible bending machine respectively. When the ten-axis flexible bending machine is initially installed, ensure that the driver of the configured axis does not enable the motor. Manually operate the driver panel to set the current position of the driver to zero.

[0132] S12. When the ten-axis flexible bending machine is initially installed, use a vernier caliper or feeler gauge or other related measuring tools to measure the offset distance between the current position of the configuration axis and the specified processing zero point, and input the offset distance value into the CNC system, and correct the position of the processing zero point at the same time.

[0133] S121. The IO output control module operates the machine tool gas circuit equipment to raise the positioning mechanism.

[0134] S122. Use a tape measure to measure the minimum distance between the edge of the positioning mechanism and the machining zero point.

[0135] S123. Record the minimum distance information through the axis motion parameter configuration function.

[0136] S13. After each power-off restart, first ensure that the driver of the configured axis does not enable the motor, and obtain the offset distance value recorded in the CNC system and the current pulse position of the configured axis driver, calculate the pulse position of the current position in the ten-axis flexible bending machine coordinate system, and set the current position of the configured axis driver to the corresponding position.

[0137] S131, the CNC system of the ten-axis flexible bending machine obtains the offset distance value. Based on the conversion relationship between the current pulse position distance and pulse value of the configured axis driver, the specific expression for converting the offset distance value into the offset pulse value is as follows:

[0138]

[0139] S132, the CNC system of the ten-axis flexible bending machine automatically obtains the current pulse position reading of the configuration axis driver through the PDO instruction, and at the same time obtains the expression of the corresponding position pulse value of the current position of the configuration axis driver in the configuration axis processing coordinate system as follows:

[0140] After the coordinate system is transformed, the corresponding position pulse = current position pulse + offset pulse.

[0141] S133, the CNC system of the ten-axis flexible bending machine sets the current position of the driver to the corresponding position pulse value through the PDO instruction.

[0142] S14. The driver of the configured axis enables the motor, thereby starting the equipment normally.

[0143] The adjustment process of the zero point setting of the gantry-driven press tool 3 in the ten-axis flexible bending machine is as follows:

[0144] S11. Install the control hardware and control software on the ten-axis flexible bending machine respectively. When the ten-axis flexible bending machine is initially installed, ensure that the master and slave drivers of the currently configured axes enable the motors, ensure that the master and slave drivers do not activate the gantry motion, adjust the master and slave motors respectively until the distance deviation between the master and slave ends of the gantry is less than 0.2mm, turn off the master and slave drivers to enable the motors, manually operate the driver panel, and set the current positions of the master and slave drivers to zero respectively.

[0145] S12. When the ten-axis flexible bending machine is initially installed, use a vernier caliper or feeler gauge or other related measuring tools to measure the distance from the lower surface of the press tool 3 to the upper surface of the processing table at the edge of the end where the active shaft of the press tool 3 is located, and input the offset distance value into the CNC system, and at the same time correct the position of the processing zero point.

[0146] S121. The IO output control module operates the machine tool gas circuit equipment to raise the positioning mechanism.

[0147] S122. Use a tape measure to measure the minimum distance between the edge of the positioning mechanism and the machining zero point.

[0148] S123. Record the minimum distance information through the axis motion parameter configuration function.

[0149] S13. After each power-off restart, first ensure that the master and slave drivers of the currently configured axes do not enable the motors, ensure that the master and slave driver gantry motion is not activated, obtain the offset distance value recorded in the CNC system and the current pulse position of the configured axis driver, calculate the pulse position of the machine coordinate system corresponding to the current position of the master and slave ends, and set the current position of the driver to the corresponding position.

[0150] S131, the CNC system of the ten-axis flexible bending machine obtains the offset distance value. Based on the conversion relationship between the current pulse position distance and pulse value of the configured axis driver, the specific expression for converting the offset distance value into the offset pulse value is as follows:

[0151]

[0152] S132, the CNC system of the ten-axis flexible bending machine automatically obtains the current pulse position reading of the configuration axis driver through the PDO instruction, and at the same time obtains the expression of the corresponding position pulse value of the current position of the configuration axis driver in the configuration axis processing coordinate system as follows:

[0153] After the coordinate system is transformed, the corresponding position pulse = current position pulse + offset pulse.

[0154] S133, the CNC system of the ten-axis flexible bending machine sets the current position of the driver to the corresponding position pulse value through the PDO instruction.

[0155] S14. The master and slave drivers of the currently configured axes enable the motors. The master and slave drivers activate the gantry motion, and the equipment can be used normally.

[0156] Figure 8 This is a clamping diagram of a ten-axis flexible bending machine clamping a plate 14 with an offset. In this embodiment, the plate 14 for forming is an aluminum plate. The offset clamping of the plate 14 for forming has an offset in both the length and width directions. Figure 7 In the clamping state, the corresponding sides of the formed sheet 14 are named as the front side, back side, left side, and right side according to their positions. Let the length of the formed sheet 14 be Y, the width be X, the distance from the front edge of the loading area of ​​the formed sheet 14 to the front edge 13 of the processing table be L, and the offset of the clamping point P from the midpoint of the formed sheet 14 in the length direction be y and in the width direction be x. The distances L1, L2, L3, and L4 from the clamping point to the four sides can be calculated using the following expressions:

[0157]

[0158]

[0159]

[0160]

[0161] When machining the front and back edges, there is an offset clamping situation for the relative machining edges. The specific implementation steps of the secondary positioning process are as follows:

[0162] S2. The size of the formed plate 14 and the clamping size of the formed plate 14 are input into the numerical control system of the ten-axis flexible bending machine, and the ten-axis flexible bending machine controls the fixing mechanism 5 and the plate loading and positioning mechanism 4 to move to the clamping position.

[0163] S3. The formed plate 14 is mounted and fixed on the fixing mechanism 5 having a crank slider.

[0164] S4. Use the feeding mechanism 1 in the ten-axis flexible bending machine to drive the formed plate 14 to move in the direction of the pressing knife 3 until the front edge of the formed plate 14 is flush with the front edge 13 of the processing table and is in a waiting state, and the front forming process begins.

[0165] S5. According to the processing length of the formed plate 14, the feeding mechanism 1 drives the formed plate 14 to move to the corresponding distance in the direction of the pressing knife 3. At this time, the pressing knife 3 presses down and fixes the plate 11, and the processing punch 7 moves to a reasonable position according to the processing path, so that the formed plate 14 is bent into shape.

[0166] S6, if the plate 14 is completed before the forming process, the processing punch 7 and the pressure knife 3 are returned to the zero position in turn, the feeding mechanism 1 is returned to the upper plate position, the pressure knife 3 is not loosened, the fixing mechanism 5 is loosened, and the processing is completed; if the plate 14 is not completed, and the processing is relatively edge, the processing punch 7 is returned to zero, the pressure knife 3 is not loosened, the fixing mechanism 5 is loosened, according to the size of the plate 14 and the offset clamping distance, the fixing mechanism 5 is advanced to the processing table direction by 2y distance, the numerical value of L1 and L3 is adjusted, the midpoint of the plate 14 is taken as the straight line perpendicular to the processing direction, the symmetric position of the current clamping position is calculated, the numerical control system of the bending machine moves the fixing mechanism 5 to the position, the fixing mechanism 5 fixes the plate 11, the pressure knife 3 is loosened, the fixing mechanism 5 drives the plate 14 to move to Figure 8 The P point position shown in the figure, the exchange mechanism 2 rotates clockwise by 180 degrees, the rear edge is exchanged to the end close to the processing table, the feeding mechanism 1 advances to the processing table direction by (L+L1-L3) distance, at this time the plate 14 is flush with the processing table, and the rear edge processing is carried out.

[0167] The specific implementation steps of the secondary positioning process method for the adjacent processing edge with offset clamping when processing the front edge and the left edge are as follows:

[0168] S2, the size of the plate 14 and the clamping size of the plate 14 are input into the numerical control system of the ten-axis flexible bending machine, and the ten-axis flexible bending machine controls the movement of the fixing mechanism 5 and the plate feeding positioning mechanism 4 to the clamping position.

[0169] S3, the plate 14 is installed and fixed on the fixing mechanism 5 with a crank slider.

[0170] S4, the feeding mechanism 1 of the ten-axis flexible bending machine drives the plate 14 to move towards the pressure knife 3, until the front edge of the plate 14 is flush with the front edge 13 of the processing table, in the state of waiting for processing, and the front edge forming processing is started.

[0171] S5, according to the processing length of the plate 14, the feeding mechanism 1 drives the plate 14 to move to the corresponding distance in the direction of the pressure knife 3, at this time the pressure knife 3 presses the plate 11, the processing punch 7 moves to a reasonable position according to the processing path, and the plate 14 is bent and formed.

[0172] S6. If the forming process of the sheet 14 is completed, the processing punch 7 and the pressing knife 3 will retreat to the zero position in turn, the feeding mechanism 1 will retreat to the upper plate position, the fixing mechanism 5 will release the sheet 11, and the processing will be completed; if the forming process of the sheet 14 is not completed, and the processing is the relative edge, the processing punch 7 will retreat to the zero point, the pressing knife 3 will not be released, the fixing mechanism 5 will be released, and according to the size of the forming process of the sheet 14 and the offset clamping distance, the straight line perpendicular to the processing direction at the midpoint of the forming process of the sheet 14 is used as the symmetry axis to calculate the symmetric position of the current clamping position, and the CNC system of the bending machine will move the fixing mechanism 5 to this position, and the fixing mechanism 5 will drive the forming process of the sheet 14 to move to Figure 8 At point P, the side-changing mechanism 2 rotates 90 degrees clockwise to move the left side closer to the end of the processing table. The feeding mechanism 1 advances a distance (L+L1-L2) toward the processing table. At this time, the formed sheet 14 is flush with the processing table, and the left side is processed.

[0173] Due to the logic of the secondary positioning operation, when the plate 14 undergoing forming processing is processed, the relative edges need to be arranged close together.

[0174] In this embodiment, the specific steps for solving the relationship between the initial angle and the final angle of the bending process are:

[0175] S1. Within the available processing area of ​​the machine tool, determine the movement path of the punch 7 during the processing of the aluminum plate, and select the trial bending points of the aluminum plate on the movement path; in this embodiment, according to the difficulty of bending and forming and the amount of bending rebound, the movement path is divided into four sections: upper bending vertical section, upper bending oblique section, lower bending vertical section and lower bending oblique section. Taking the upper bending vertical section of the 1.5mm aluminum plate as an example, a trial bending point of the plate is selected on the processing section with a fixed step length of 0.5mm, and the trial bending points are selected in the same way for the remaining three processing sections.

[0176] Fix the aluminum plate to the loading area, manually control the feeding mechanism 1 to send the aluminum plate to a distance on the processing table, and fix the aluminum plate with the pressing knife 3; manually control the processing punch 7 to move to the trial folding point position according to the processing method. After the processing is completed, control the processing punch 7 to restore the position and lift the pressing knife 3; manually control the feeding mechanism 1 to return the plate 11, unload the aluminum plate, and measure the obtained angle.

[0177] S2. The aluminum plate bending process is simulated through the manual mode of the CNC system. The aluminum plate bending test point is selected as the processing end point. The plate is repeatedly placed on the test folding and the test folding results are measured. The test folding data can be obtained as shown in Table 1.

[0178] Table 1

[0179]

[0180] S3. Under the premise of taking into account accuracy and avoiding overfitting, the relationship between the initial angle and the final angle of the bending process of the aluminum plate is fitted to obtain the relationship function under this condition.

[0181] For the data in Table 1, exponential function, linear function, quadratic function and cubic function are used to fit the data to the relationship function between distance t and final forming angle γ. The specific implementation steps of the quadratic function fitting process are:

[0182] The quadratic function fitting model expression is:

[0183] t=a0+a1*γ+a2*γ 2

[0184] According to the data series (γ i ,t i ), i=1,2,……,10, according to the principle of minimum mean square error, the matrix calculation equation of function fitting can be obtained as follows:

[0185]

[0186] Define matrix X as the α matrix on the left side of the equation, matrix A as the coefficient matrix on the left side of the equation, and matrix Y as the t matrix on the right side of the equation. Calculate the relevant data and enter them into the corresponding matrix.

[0187] Obtain the inverse matrix of matrix X and multiply it with matrix Y to obtain the coefficient matrix A and the relationship:

[0188] t=-0.0036γ 2 +0.0924γ+0.2713

[0189] In the same way, the fitting function expressions can be obtained respectively. Under the premise of taking into account accuracy and avoiding overfitting, the relationship function between the optimal distance t and the final forming angle γ (rad) can be obtained as follows:

[0190] t=-0.097γ+5.932

[0191] Based on this function, the relationship between the processing end point position and the final forming angle γ in the processing section can be obtained.

[0192] S4. Integrate all functional relationships with material and aluminum plate thickness conditions to obtain a relational function library.

[0193] The above embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A multi-axis flexible bending machine CNC system based on a motion control card, which includes control hardware and control software, characterized in that: The control hardware includes an industrial computer, an operation panel, a display screen, a motor, a motion control card, a driver, and a feedback information element. The operation panel is connected to a first connection end of the industrial computer via an input module, the display screen is connected to a second connection end of the industrial computer via an output module, the first end of the driver is connected to a first end of the motion control card via a Category 6a network cable, the second and third ends of the driver are respectively connected to a control end of the motor and the feedback information element, and the second end of the motion control card is connected to a third connection end of the industrial computer via a Category 6a network cable, thereby achieving real-time two-way data interaction and effectively coping with communication disturbances at the production site. Two adjacent drivers are connected to each other via the Category 6a network cable, thereby forming a bus topology. The control software adopts a layered design, which includes a back-end logic layer, a front-end control layer, and a communication layer for front-end and back-end information interaction; The front-end control layer includes a motion control module, an IO output control module and an IO input detection module. The motion control module obtains different motion forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction; the IO output control module outputs different control forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction; the IO input detection module outputs different operation forms according to the motion logic transmitted by the communication layer of the front-end and back-end information interaction. The back-end logic layer includes a function library, a parameter configuration module, a file operation module, a manual module, a plate processing module, an auxiliary control module and a status display module; the parameter configuration module includes hardware parameter configuration, axis motion parameter configuration and assembly error parameter configuration; specifically: the motion control card will lose some configuration information after power failure, and the hardware parameter configuration realizes that the configuration information is automatically reconfigured to the motion control card after the control card is powered on; the assembly error parameter configuration records the error data during the production and assembly process of the machining center, and compensates for the error when generating the motion distance, thereby improving the machining accuracy; the axis motion parameter configuration includes transmission ratio, reverse clearance, running speed, acceleration, limit and zero offset information, which serves as reference information when the logic of each axis motion mode is generated. The file operation module is used to process the CNC program for plate bending processing; the CNC program includes processing technology, processing length, and other parameters. Degrees and processing angles; the manual module includes single-axis free manual control, zero return, press release, loading preparation and plate fixing; the single-axis free manual control includes inching control mode, fixed position movement control mode and fixed distance movement control mode; the plate processing module, based on the needs of plate processing and forming and the needs of complete forming in one loading, designs and implements the upper bending, lower bending, upper edge pressing and lower edge pressing processing processes realized by controlling the bending punch and press, and the plate fixing, edge changing and secondary positioning processing connection process realized by controlling the feeding mechanism, fixing mechanism and edge changing mechanism, which includes bending process, edge pressing process, edge changing process, feeding mechanism control, fixing mechanism control and edge changing mechanism control; the auxiliary control module includes reset, zero return and ratio adjustment; the secondary positioning process for offset clamping processing of special-shaped plates and the function library for realizing accurate rebound compensation of plate bending processing.

2. The multi-axis flexible bending machine CNC system based on the motion control card according to claim 1 is characterized in that: The communication layer for front-end and back-end information interaction realizes real-time communication through the EtherCAT protocol.

3. The multi-axis flexible bending machine CNC system based on motion control card according to claim 1 is characterized in that: The control hardware adopts a dual CPU bus type hardware architecture using a PC+motion control card mode.

4. The multi-axis flexible bending machine CNC system based on motion control card according to claim 1 is characterized in that: The inching control mode includes 0.01mm inching distance selection or continuous inching mode selection, 0.1mm inching distance selection or continuous inching mode selection and 1mm inching distance selection or continuous inching mode selection.

5. A control method for a multi-axis flexible bending machine CNC system based on a motion control card according to any one of claims 1 to 4, characterized in that: It includes the following steps: S1. Zero point setting of related motion mechanisms in the bending machine: S11. Install the control hardware and control software on the machine tool respectively, and ensure that the driver of the configured axis does not enable the motor, and set the current position of the driver to zero; S12, using relevant measuring tools to measure the offset distance between the configuration axis at its current position and the specified machining zero point, and inputting the offset distance value into the numerical control system, while correcting the position of the machining zero point; S13. After each power-off restart, first ensure that the driver of the configured axis does not enable the motor, obtain the offset distance value recorded in the CNC system and the current pulse position of the configured axis driver, calculate the pulse position of the current position in the machine tool coordinate system, and set the current position of the configured axis driver to the corresponding position; S14, the driver of the configured axis enables the motor, thereby starting the device normally; S2. Input the plate size and plate clamping size into the CNC system of the bending machine, and the bending machine controls the fixing mechanism and the plate loading and positioning mechanism to move to the clamping position; S3. Install the plate on a fixed mechanism with a crank slider and obtain the initial assembly angle error in the assembly error parameter configuration of the CNC system of the bending machine. and initial assembly distance error , as the position control function of the P-axis motion of the bending machine, the motion of the fixing mechanism is accurately controlled by the crank slider. The expression of the motion function of the crank slider is as follows: ； in, is the angle between the upper crank and the vertical plane, is the distance from the lower surface of the pressing block to the upper surface of the turntable, and are the lengths of the upper crank and lower crank of the slider-crank mechanism, respectively. The expression between the angle and the distance is: ； S4. Use the feeding mechanism in the bending machine to drive the plate to move in the direction of the pressing knife until the front edge of the plate is flush with the front edge of the processing table and is in a state to be processed; S5. According to the processing length of the plate, the feeding mechanism drives the plate to move to the corresponding distance in the direction of the pressing knife. At this time, the pressing knife presses down and fixes the plate, and the processing punch moves to a reasonable position according to the processing path to bend the plate into shape; S6. Select different operation modes according to the processing and clamping methods of the plate: If the sheet forming process is normal clamping, the specific implementation steps are as follows: If the plate processing is completed, the processing punch and the pressing knife will return to the zero position in sequence, the feeding mechanism will return to the upper plate position, the fixing mechanism will release the plate, and the processing will be completed; if the plate processing is not completed and the processing is still on the current side, the processing punch and the pressing knife will return to the waiting position in sequence, and the process will continue to step S5; if the plate processing is not completed and other sides need to be processed, the processing punch and the pressing knife will return to the zero position in sequence, the feeding mechanism will return to the upper plate position, and the side changing mechanism will rotate the plate to the corresponding processing side, and the process will continue to step S4; If the sheet metal forming process is to have adjacent edges with offsets, the specific implementation steps are as follows: If the plate processing is completed, the processing punch and the pressing knife will return to the zero position in sequence, the feeding mechanism will return to the upper plate position, the fixing mechanism will release the plate, and the processing will be completed; if the plate processing is not completed and the processing is still on the current side, the processing punch and the pressing knife will return to the waiting position in sequence, and the process will continue to step S5; if the plate processing is not completed and the processing is on the adjacent side, the processing punch and the pressing knife will return to the zero position in sequence, the feeding mechanism will return to the upper plate position, and the side changing mechanism will rotate the plate to the corresponding processing side, and the process will continue to step S4; If the sheet metal is formed into opposite edges with offsets, the specific implementation steps are as follows: If the plate processing is completed, the processing punch and the pressing knife will return to the zero position in sequence, the feeding mechanism will return to the upper plate position, the fixing mechanism will release the plate, and the processing will be completed; if the plate processing is not completed, and the processing is still the current side, the processing punch and the pressing knife will return to the waiting position in sequence, and continue with step S5; if the plate processing is not completed, and the processing is the relative side, the processing punch will return to the zero point, the pressing knife will not be released, the fixing mechanism will be released, and according to the plate size and offset clamping distance, the straight line at the midpoint of the plate perpendicular to the processing direction is used as the symmetry axis to calculate the symmetric position of the current clamping position, the CNC system of the bending machine will move the fixing mechanism to this position, the fixing mechanism will fix the plate, the pressing knife will be released, the feeding mechanism will return to the upper plate position, the side changing mechanism will rotate the plate to the corresponding processing side, and continue with step S4.

6. The control method of the multi-axis flexible bending machine numerical control system based on the motion control card according to claim 5 is characterized in that: The step S12 specifically includes the following steps: S121, the IO output control module operates the machine tool gas circuit equipment to raise the positioning mechanism; S122. Use a tape measure to measure the minimum distance between the edge of the positioning mechanism and the processing zero point; S123. Record the minimum distance information through axis motion parameter configuration.

7. The control method of the multi-axis flexible bending machine numerical control system based on the motion control card according to claim 5 is characterized in that: The step S13 specifically includes the following steps: S131. The CNC system of the bending machine obtains the offset distance value. Based on the conversion relationship between the current pulse position distance and pulse value of the configured axis driver, the specific expression for converting the offset distance value into the offset pulse value is as follows: ； S132, the bending machine CNC system automatically obtains the current pulse position reading of the configuration axis driver through the PDO instruction, and at the same time obtains the expression of the corresponding position pulse value of the current position of the configuration axis driver in the configuration axis machining coordinate system as follows: ； S133, the bending machine CNC system sets the current position of the driver to the corresponding position pulse value through the PDO instruction.

8. The control method of the multi-axis flexible bending machine numerical control system based on the motion control card according to claim 5 is characterized in that: The steps for solving the relationship between the initial angle and the final angle of the bending process are as follows: S1. Determine the motion path of the punch during sheet metal forming within the available processing area of ​​the machine tool, and select a test bending point for the sheet metal on the motion path; S2. Select plates of different materials and thicknesses, simulate the plate bending process through the manual mode of the CNC system, select the plate bending test point as the processing end point, repeatedly place the plate on the test bending and measure the test bending results; S3. Fitting the relationship between the initial angle and the final angle of the bending process under different material and plate thickness conditions, thereby obtaining a relationship function under the conditions; S4. Integrate all functional relationships with material and plate thickness conditions to obtain a relational function library.

9. The control method of the multi-axis flexible bending machine numerical control system based on the motion control card according to claim 5 or 8, characterized in that: The fitting functions include exponential function, linear function, quadratic function and cubic function.

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