Flexible control system based on PLC automatic welding equipment

Abstract

The invention discloses a flexible control system based on PLC automatic welding equipment. The flexible control system comprises a master control unit, a configuration screen, a manual control box, a machine head unit, a wire feeder unit, a non-standard tool unit, a positioner unit and a welding machine unit. The master control unit is a core control unit and integrates control modules of a configuration screen, a manual control box, a machine head unit, a wire feeder unit, a non-standard tool unit, a positioner unit and a welding machine unit. The general control unit carries out modular programming on all the control modules, the different control modules are activated or shielded through the configuration screen, meanwhile, an operator sets the motion logic of the executing mechanism and the time sequence of the welding technology in the touch screen, and therefore the purpose of controlling different welding devices is achieved. According to the method, the welding efficiency is improved, the time cost and the technical cost caused by programming of different welding tools are reduced, the wiring number is reduced, and therefore the fault occurrence rate is reduced.

Description

Technical Field

[0001] The invention relates to the field of welding control systems, in particular to the field of flexible welding control systems with modular design. Background Art

[0002] As the market demand for product diversity and customization grows, welding systems must be highly adaptable and flexible to quickly respond to changing production needs. Against this backdrop, many old equipment are facing the challenge of equipment replacement. Traditional welding equipment often fails to meet the needs of modern production, especially in terms of precision, efficiency and flexibility. The elimination of old equipment will waste certain resources. Therefore, the use of fieldbus technology to transform equipment can not only extend the service life of existing equipment, but also significantly improve production efficiency and product quality. This transformation strategy is not only economical, but also in line with the concept of sustainable development. At the same time, this study will use the widely used RS485 communication to simplify the entire system structure.

[0003] Traditional automatic welding equipment is generally a special machine type. One set of equipment corresponds to one control system. Different control systems need to be developed for different types of special machines, which greatly increases the time and technical costs of production. The flexible control system with modular design can provide a more flexible solution.

[0004] The advantage of the flexible control system based on PLC automated welding equipment is its high modularity and adaptability, which can quickly adapt to different welding tasks and environments, while maintaining high efficiency and high quality welding results, and reducing the time and technical costs of developing different welding machine control systems. In addition, as the concepts of intelligent manufacturing and Industry 4.0 are gaining popularity, the intelligent and flexible characteristics of this system are also increasingly valued. Summary of the invention

[0005] The technical purpose of the present invention is to propose a flexible control system based on PLC automated welding equipment, aiming to realize the automated control and flexible combination of welding processes. The system includes multiple independent modules including a master control unit, a configuration screen (touch screen), a hand control box, a head unit, a wire feeder unit, a non-standard tooling unit, a positioner unit and a welding unit. These modules can be combined according to actual project requirements to complete the control and operation of different welding tasks.

[0006] The present invention uses Siemens S7-1200PLC as the controller, the configuration screen as the host computer to convey control instructions to the PLC controller, the hand control box as the auxiliary control device, and the lower computer includes a head unit, a wire feeder unit, a non-standard tooling unit, a positioner unit and a welding machine unit. The controller communicates with the lower computer through a switch and a distributed IO-Link module, and the communication method uses the Profinet field bus protocol and the RS485 bus communication protocol.

[0007] The technical solution adopted by the present invention is a flexible control system based on PLC automated welding equipment, including a master control unit, a configuration screen (touch screen), a manual control box, a head unit, a wire feeder unit, a non-standard tooling unit, a positioner unit and a welding machine unit.

[0008] The master control unit is the core control unit, which integrates the control modules of the configuration screen, manual control box, head unit, wire feeder unit, non-standard tooling unit, positioner unit and welding unit. The master control unit performs modular programming on each control module. According to different welding equipment, different control modules are activated or shielded through the configuration screen, or the local control mode, remote control mode and manual automatic mode are switched in the master control unit of the configuration screen. At the same time, the operator sets the motion logic of the actuator and the timing of the welding process on the touch screen to achieve the purpose of controlling different welding equipment. The master control unit communicates with the lower computer through the switch and the distributed IO-Link module, and the communication method uses the Profinet field bus protocol and the RS485 bus communication protocol.

[0009] Furthermore, the head unit is used to control the welding head. The welding head is installed on a non-standard tooling or the end of a robot to realize the welding function, and is controlled as an independent execution unit. The welding head includes a laser arc height motion axis, a head swing axis, a wire feeding lifting axis, a wire feeding lateral axis, a welding gun rotation axis, a fast gun feed linear motion axis, and a fast gun feed cylinder axis. The motor of the head unit uses a stepper motor drive control integrated machine with RS485 Modbus communication. The laser arc height motion axis is specially designed for arc welding process. Since the linearity of the matching relationship between welding voltage and actual arc length is poor, in order to solve this problem, a high-precision laser ranging sensor is used to measure the distance between the welding gun and the surface in real time, and the closed-loop feedback control is used to ensure that the welding torque and the workpiece maintain a fixed height, that is, the welding gun rises and falls with the change of the welding surface, and then automatically tracks and stabilizes the height of the welding arc. The head swing axis realizes the left and right swing of the welding gun along the weld direction, expands the coverage area of ​​the molten pool, increases the weld width, improves weld formation and improves productivity. The wire feeding lifting axis and wire feeding traverse axis are used to adjust the position of the wire feeding mechanism to ensure that the welding wire and the welding workpiece reach the optimal distance for welding, thereby ensuring the welding quality and adapting to different welding requirements. The welding gun rotating axis can realize the rotation adjustment of the welding arc, thereby ensuring the welding quality and improving the welding efficiency. The fast-feeding gun linear motion axis and the fast-feeding gun cylinder axis are both used to enable the welding gun to quickly reach the specified position and improve the welding efficiency. According to the actual environment, choose the motor axis or the cylinder axis.

[0010] Furthermore, the hand control box changes the hard wiring of the hand control box into an RS485 digital input and output module; the original complex terminal block is changed into a remote field bus IO module, which reduces the cumbersome wiring work in the traditional wiring method and simplifies the entire system structure.

[0011] Furthermore, the fast-feed linear motion axis and the fast-feed cylinder axis of the head unit can be activated or shielded in the configuration screen, and the remaining motor shafts, as necessary actuators and fixed axes of the system, are not activated or shielded. The mechanical parameters have been set, and only the motion parameters can be set.

[0012] Furthermore, the wire feeder unit is used in conjunction with the general automatic welding machine tools of the annular and longitudinal seam series and the plasma welding machine to complete the automatic wire feeding of plasma welding. There are two forms of the overall hardware drive scheme of the wire feeder unit: a driver using the Profinet field bus communication method and a hardware architecture of a matching stepper motor or servo motor; and an integrated stepper motor using the RS485 bus communication method. The process parameters that can be set in the wire feeder are peak wire feeding speed, bottom wire feeding speed, peak time, bottom time, wire retraction speed, wire retraction time, inching wire feeding speed, inching wire retraction speed, start delay time, stop delay time, etc. The peak wire feeding speed and bottom wire feeding speed of the wire feeder can be set in the configuration screen to achieve variable speed or pulsating wire feeding, and the speeds of the two can also be set to the same value to achieve constant speed wire feeding.

[0013] Furthermore, the non-standard tooling unit involves welding tooling, including longitudinal seam welding tooling, circumferential seam welding tooling and spiral welding tooling. The design and manufacture of these tooling can be customized according to specific production needs to meet various complex production operation requirements. The non-standard tooling hardware architecture is designed with electric actuators and pneumatic actuators, multiple motor shafts (servo motors, stepper motor types, all process shafts), multiple cylinder shafts, and two airbags. Each motor shaft is equipped with 3 limit sensors, and each cylinder shaft and airbag is equipped with 2 limit sensors.

[0014] Furthermore, the positioner unit is used to adjust the posture of the workpiece to be welded so that the workpiece to be welded can be moved to the most suitable welding position. The positioner hardware architecture has electric actuators and pneumatic actuators, five motor axes (servo motors, stepper motor types), and multiple cylinder axes, which can achieve a maximum of five degrees of freedom. The control logic is the same as that of the non-standard tooling unit, and the five motors of the positioner unit are all non-process motor axes.

[0015] Furthermore, the laser arc height motion axis and the head swing axis can be used as both process axes (the process axis can move during the welding process) and ordinary linear motion axes. When the two axes are selected as process axes, the corresponding process parameters will be equipped in the configuration plane: the process parameters of the laser arc height axis are deviation calibration value, arc height target value, hysteresis HY, manual speed, deviation H1, deviation H2, deviation H3, low speed, medium speed, high speed, and ultra-high speed; the process parameters of the swing axis are start delay time, stop delay time, swing speed, swing range, left dwell time, right dwell time, center dwell time, manual speed, initial swing direction, and center adjustment range. When selected as an ordinary linear motion axis (non-process axis, cannot move during the welding process), the process parameter settings will not appear, only the mechanical parameters, motion parameters, and limit parameter settings will appear. The motor of the non-process axis will directly enter the setting of mechanical parameters and motion parameters, and can only perform inching motion, not complex motion.

[0016] Furthermore, after entering the configuration screen, the motor axis of the non-fixed axis is activated or shielded, and after activation, the mechanical parameters and motion parameters are set. The mechanical parameters include selecting the mechanical transmission form and entering the relevant mechanical parameters. For example, the mechanical parameters to be filled in when selecting the screw transmission are the reduction ratio and the screw lead; the mechanical parameters to be filled in when selecting the rack and pinion transmission are the reduction ratio and the gear pitch circle diameter. The motion parameters include acceleration, deceleration, speed and other parameters.

[0017] Furthermore, the electric actuator is mainly a motor shaft. The motor shaft is designed with a stepper motor or a servo motor. The motor shaft can be used as a moving shaft or a rotating shaft. The driver is driven by the Profinet bus protocol. The motor shaft is designed with starting point, zero point, and end point position detection sensors, and has a return to zero function. The touch screen can set various mechanical parameters of the motor shaft, such as the reduction ratio, lead screw, etc. At the same time, various motion parameters of the motor shaft can be set. The control of the motor shaft is divided into two types: local control and remote control. Local control is a jog control through a handheld control box. This control mode can only be enabled when the operating mode is manual mode; remote control is a control method through a touch screen or other peripheral devices.

[0018] Furthermore, the pneumatic actuator unit includes multiple dual-control cylinders and two air bags. Each pneumatic actuator unit has starting and end position detection sensors. The valve island that controls the pneumatic unit communicates directly with the PLC, and the limit sensor transmits the limit signal to the PLC through the remote IO module.

[0019] Compared with the prior art, the flexible control system based on PLC automated welding equipment provided by the present invention enables a set of systems to control a variety of different welding equipment within a certain framework after simple settings. The present invention shows great potential in improving welding efficiency, reducing the time and technical costs of programming different welding tools, ensuring welding quality, and meeting personalized production needs. At the same time, the present invention adopts bus communication to reduce the number of connections, thereby reducing the occurrence of failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the hardware framework of the present invention.

[0021] Figure 2 It is the operation flow chart of the master control unit.

[0022] Figure 3 It is a logic diagram of laser arc high axis control.

[0023] Figure 4 It is the logic diagram of swing axis control.

[0024] Figure 5 It is a schematic diagram of the wire feeder control logic.

[0025] Figure 6 It is a schematic diagram of process axis control logic.

[0026] Figure 7 It is a logic diagram of non-process axis control.

[0027] Figure 8 This is the logic diagram of cylinder shaft control. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0029] refer to Figure 1 The hardware framework of the flexible control system based on PLC automated welding equipment designed by the present invention is shown in the figure. The whole system includes Siemens S7-1200PLC, CM 1241 communication module, human-computer interaction configuration screen, 485 hub, industrial Ethernet switch, manual control box, welding power supply, driver, motor, valve island, cylinder, airbag, remote IO module and limit sensor.

[0030] The PLC communicates with the motor driver, valve island, remote IO module, and configuration plane of Profinet communication through the industrial Ethernet switch, and communicates with the motor driver, hand control box, and welding power supply of 485 communication through the 485 hub, so that the motor driver controls the movement of the motor and the valve island controls the movement of the cylinder. The limit sensor feeds back the signal to the PLC through the remote IO module, thereby limiting the unreasonable movement of the motor and the cylinder and ensuring the safety of the movement process. The hand control box communicates with the PLC through the RS485 digital input and output module. The use of the remote IO module of the field bus and the RS485 digital input and output module simplifies the hardware structure of the control system. The operator can interact with the system through the hand control box and the configuration screen to control the movement and welding parameters of the entire system.

[0031] In actual use, only a few specific motion axes are selected from the selected hardware architecture to combine to achieve the actual application effect. After selecting the required hardware, configure the required hardware in the program, map the variables in the actuator, and then activate the required program modules in the configuration screen, shield the unnecessary program modules, and adjust some hardware parameters and drive parameters in the required program modules. At the same time, set the motion sequence of the actuator and the welding sequence on the touch screen, and then you can start welding.

[0032] Implementation method Figure 2As shown: First, after the control system is started, according to the hardware and process requirements of the controlled automated welding equipment, simple hardware configuration and variable mapping are performed in the master control unit program, the required functional units are activated, the unnecessary functional units are shielded, and the various parameters of the required units are set; then the motion logic of the actuator and the welding timing are set to ensure the accuracy and safety of the welding process; after setting all parameters and logic, manual, automatic mode, remote control, and local control mode are selected, and the entire set of welding equipment is adjusted into place according to the selected mode; after the adjustment is in place, a start trigger signal is given, and each functional unit will perform the automated welding process according to the set method, and a stop trigger signal is given, and the system will stop working.

[0033] Figure 3 This is a logic diagram of laser arc high axis control. After the system is started, enter the interface for setting the function requirements of each axis on the touch screen, and choose whether to activate the laser arc high axis according to the actual situation. If not, enter the ordinary motion axis state and set the ordinary axis motion parameters; if yes, enter the laser arc high axis state and set the laser arc high parameters. In the ordinary motion axis state, you can only enter the next step in the manual operation mode. After selecting the manual operation mode, select the control mode of near control or remote control. The near control mode is controlled on the hand control box, and the remote control is controlled on the touch screen or other peripheral devices. Then press the button to control the motor's motion. After running to the limit position, the system will alarm, prompting the motor to run to the limit position, and stop the motor. In the laser arc high axis state, select automatic or manual operation mode. After selecting the manual operation mode, select the control mode, and then use different devices to adjust the welding gun to the appropriate position. After selecting the automatic operation mode, the laser arc height module will automatically adjust the arc height according to the set parameters after receiving the welding start signal. When the arc height is within the deviation range, the motor will stop rotating. When the arc height reaches the deviation range, it does not exceed the measurement, and the system continues to adjust the arc height. If it exceeds the measurement range, the system alarms and returns to the manual operation mode. The welding gun is manually adjusted to the appropriate position. The arc height will continue to be adjusted before the welding stop signal is input. After the welding stop signal is input, the automatic tracking of the arc height ends.

[0034] Figure 4This is a logical diagram of the swing axis control. After the system is started, enter the interface for setting the function requirements of each axis on the touch screen, and choose whether to activate the swing axis according to the actual situation. If you choose not to activate the swing axis, the system will switch to the normal motion axis state and require the setting of the corresponding motion parameters. In this state, the operation can only be continued if the manual operation mode is selected. Then the user can decide to use the near control mode (direct control using the hand control box) or the remote control mode (remote control through the touch screen or other external devices). After selecting the control mode, start the motor through the manual button to realize the movement control of the welding gun. When the motor moves to the preset limit, the system will automatically alarm and stop the motor to prevent damage. If you choose to activate the swing axis, the system will enter the unique workflow of the swing axis, and the user can configure the relevant parameters of the swing axis. In the swing axis mode, two operation modes, automatic and manual, are also provided. When manual is selected, the user needs to manually adjust the welding gun to a suitable position through the hand control box or peripherals. If automatic operation is selected, after receiving the welding start signal, the system starts the swing axis function according to the start synchronization mode. In the time synchronization mode, the swing axis starts after the delay time is reached; in the key signal synchronization mode, the swing axis starts after receiving the key signal. Similarly, after the welding stop signal is given, the swing axis stops in the same synchronization mode, and finally ends the swing.

[0035] Figure 5 This is a schematic diagram of the wire feeder control logic. After the system is started, enter the wire feeder setting interface on the touch screen to select whether to activate the wire feeder. If not, the wire feeder-related operations are disabled; if yes, set the wire feeder's communication mode (Profinet communication or Modbus communication), motor type (servo motor or stepper motor) and wire feeder-related parameters. Select automatic or manual operation mode. In manual operation mode, use the wire feed button and wire retract button to make the wire feeder move at the specified speed. In automatic operation mode, after receiving the welding start signal, the system starts the wire feeder function according to the start synchronization mode. In time synchronization mode, the wire feeder starts when the delay time is reached; in key signal synchronization mode, the wire feeder starts after receiving the key signal. Similarly, after the welding stop signal is given, the wire feeder stops in the same synchronization mode, and finally ends the swing.

[0036] Figure 6This is a schematic diagram of the process axis control logic. After the system is started, enter the interface for setting the function requirements of each axis on the touch screen, and choose whether to activate this process axis according to the actual situation. If not, the operations related to the process axis are disabled. If yes, set the function requirements (rotation or linear), motor type, and mechanical and motion parameters of this axis. Select automatic or manual operation mode. After selecting manual operation mode, select the control mode of local control or remote control, and then use different devices to adjust this process axis to a suitable position. After selecting the automatic operation mode, after receiving the welding start signal, the system starts the function of this process axis according to the start synchronization mode. In the time synchronization mode, the axis starts after the delay time is reached; in the key signal synchronization mode, the process axis starts after receiving the key signal. Similarly, after the welding stop signal is given, the principle of the synchronization mode of the process axis stop is the same, and the movement ends at last.

[0037] Figure 7 This is a logic diagram of non-process axis control. After the system is started, enter the interface for setting the function requirements of each axis on the touch screen, and choose whether to activate this non-process axis according to the actual situation. If not, the operations related to the process axis are disabled. If yes, set the function requirements (rotation or linear), motor type, and mechanical and motion parameters of this axis. Then select the operation mode and control mode of this axis to control the forward and reverse rotation of this axis. After stopping the operation, the process ends.

[0038] Figure 8 This is a schematic diagram of the cylinder axis control logic. After the system is started, enter the interface for setting the function requirements of each axis on the touch screen, and choose whether to activate this cylinder axis according to the actual situation. If not, the corresponding button of the cylinder axis is invalid. If yes, select the operation mode of the cylinder. Only when the manual mode is selected can the next operation be performed. Then select the local control or remote control mode to use different devices to control the extension and retraction of the cylinder. Press the gun retraction button, the cylinder retracts, and the process ends. Press the gun advance button, the cylinder extends, and detects whether the cylinder reaches the specified position. If not, the cylinder keeps extending. If yes, the system can receive the arc start signal. During the welding process, the cylinder retraction action will be prohibited. When not in the welding process, the cylinder can continue to move.

Claims

1. A flexible control system based on PLC automated welding equipment, characterized in that: It includes multiple independent modules such as master control unit, configuration screen, manual control box, head unit, wire feeder unit, non-standard tooling unit, positioner unit and welding machine unit; The master control unit is the core control unit, which integrates the control modules of the configuration screen, manual control box, head unit, wire feeder unit, non-standard tooling unit, positioner unit and welding machine unit; the master control unit performs modular programming on each control module, activates or shields different control modules through the configuration screen according to different welding equipment, or switches the local control mode, remote control mode and manual automatic mode in the master control unit of the configuration screen, and the operator sets the motion logic of the actuator and the timing of the welding process on the touch screen to control different welding equipment; the master control unit communicates with the lower computer through the switch and the distributed IO-Link module, and the communication method uses the Profinet field bus protocol and the RS485 bus communication protocol.

2. A flexible control system based on PLC automated welding equipment according to claim 1, characterized in that: The head unit is used to control the welding head; the welding head is installed on a non-standard tooling or the end of a robot to realize the welding function, and is controlled as an independent execution unit.

3. A flexible control system based on PLC automated welding equipment according to claim 1, characterized in that: The manual control box changes the hard wiring of the manual control box to an RS485 digital input and output module.

4. A flexible control system based on PLC automated welding equipment according to claim 1, characterized in that: The fast-feeding linear motion axis and the fast-feeding cylinder axis of the head unit are activated or shielded in the configuration screen, and the remaining motor axis is used as an actuator and a fixed axis of the system and is not activated or shielded.

5. The flexible control system based on PLC automated welding equipment according to claim 1 is characterized in that: The wire feeder unit is used in conjunction with the general automatic welding machine tools of the ring and longitudinal seam series and the plasma welding machine to complete the automatic wire feeding of plasma welding; the overall hardware drive scheme of the wire feeder unit has two forms: a driver using the Profinet field bus communication method and a hardware architecture of a matching stepper motor or servo motor; an integrated stepper motor using the RS485 bus communication method; the process parameters set in the wire feeder are peak wire feeding speed, bottom wire feeding speed, peak time, bottom time, wire drawing speed, wire drawing time, inching wire feeding speed, inching wire retracting speed, start delay time, and stop delay time; The peak wire feeding speed and bottom wire feeding speed of the wire feeder are set in the configuration screen.

6. The flexible control system based on PLC automated welding equipment according to claim 1 is characterized in that: The non-standard tooling unit involves welding tooling, including longitudinal seam welding tooling, circumferential seam welding tooling and spiral welding tooling; the non-standard tooling hardware architecture is designed with electric actuators and pneumatic actuators, multiple motor shafts, multiple cylinder shafts, and two airbags; each motor shaft is equipped with 3 limit sensors, and each cylinder shaft and airbag is equipped with 2 limit sensors.

7. The flexible control system based on PLC automated welding equipment according to claim 1 is characterized in that: The positioner unit is used to adjust the posture of the workpiece so that the workpiece to be welded can be moved to the most suitable welding position; the positioner hardware architecture has electric actuators and pneumatic actuators, five motor axes, and multiple cylinder axes, which can achieve a maximum of five degrees of freedom. The control logic is the same as the non-standard tooling unit, and the five motors of the positioner unit are all non-process motor axes.

8. The flexible control system based on PLC automated welding equipment according to claim 1 is characterized in that: The laser arc height motion axis and the machine head swing axis can be used as process axes or as ordinary linear motion axes. When the two axes are selected as process axes, the configuration platform will be equipped with corresponding process parameters: the process parameters of the laser arc height axis are deviation calibration value, arc height target value, hysteresis HY, manual speed, deviation H1, deviation H2, deviation H3, low speed, medium speed, high speed, and ultra-high speed; the process parameters of the swing axis are start delay time, stop delay time, swing speed, swing range, left dwell time, right dwell time, center dwell time, manual speed, initial swing direction, and center adjustment range; when selected as an ordinary linear motion axis, the process parameter settings will not appear, only the mechanical parameters, motion parameters, and limit parameter settings will appear; the motor of the non-process axis will directly enter the mechanical parameter and motion parameter settings, and can only perform inching motion.

9. The flexible control system based on PLC automated welding equipment according to claim 1, characterized in that: After entering the configuration screen, activate or shield the motor axis of the non-fixed axis, and set the mechanical parameters and motion parameters after activation; the mechanical parameters include selecting the mechanical transmission form and entering the relevant mechanical parameters; the mechanical parameters that need to be filled in when selecting the gear rack transmission are the reduction ratio and the gear pitch circle diameter; the motion parameters include acceleration, deceleration, and speed.

10. The flexible control system based on PLC automated welding equipment according to claim 1, characterized in that: The electric actuator is the motor shaft. The motor shaft is designed with a stepper motor or a servo motor, and the motor shaft is used as a moving shaft or a rotating shaft. The driver is driven by the Profinet bus protocol. The motor shaft is designed with starting point, zero point, and end point position detection sensors, and has a return to zero function. The touch screen sets the various mechanical parameters of the motor shaft; at the same time, the various motion parameters of the motor shaft can be set. The control of the motor shaft is divided into two types: local control and remote control. Local control is performed by a handheld control box for jog control. This control method is enabled only when the operating mode is manual mode; remote control is a control method through a touch screen or other peripheral devices; the pneumatic actuator includes multiple double-controlled cylinders and two air bags. Each pneumatic actuator has a starting point and end point position detection sensor. The valve island that controls the pneumatic unit communicates directly with the PLC, and the limit sensor transmits the limit signal to the PLC through the remote IO module.

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