Liner Welding Control Circuit, Welding Equipment and Welding Control Method

Abstract

The present application relates to a liner welding control circuit, a welding device and a welding control method. The welding control circuit includes a digital control circuit, and a current sampling feedback circuit, a drive circuit and a torch control circuit connected to the digital control circuit; the current sampling feedback circuit is used to sample the initial current of the liner to obtain a sampled current value; the digital control circuit is used to obtain the current difference between the sampled current value and the standard current value, and output an initial PID control parameter according to the current difference; the drive circuit is used to adjust the initial current according to the initial PID control parameter so that the adjusted current has a constant pulse waveform; the digital control circuit is further used to output a speed control signal according to the standard speed; the torch control circuit is used to control the torch to rotate at a preset speed according to the speed control signal to weld the liner. The technical solution provided by the embodiments of the present application can achieve refined welding control of the liner welding.

Description

Technical Field

[0001] The present application relates to the field of circuit technologies, and particularly to a liner welding control circuit, a welding device, and a welding control method. Background Art

[0002] As a small-diameter part, the liner is widely used in various projects, such as pipeline projects. Generally, its material is metal, and it consists of an inner liner and an outer liner. During use, the inner liner and the outer liner need to be welded together to achieve welding repair.

[0003] The thicknesses of the inner liner and the outer liner are generally about one millimeter, which belong to fine parts. In view of this, providing a liner welding control circuit that can achieve fine welding control for liner welding has become an urgent problem to be solved at present. Summary of the Invention

[0004] Embodiments of the present application provide a liner welding control circuit, a welding device, and a welding control method, which can achieve fine welding control for liner welding.

[0005] In a first aspect, a liner welding control circuit is provided, including a digital control circuit, and a current sampling feedback circuit, a driving circuit, and a torch control circuit connected to the digital control circuit;

[0006] The current sampling feedback circuit is configured to sample the initial current of the liner to obtain a sampled current value;

[0007] The digital control circuit is configured to obtain the current difference between the sampled current value and the standard current value, and output an initial PID control parameter according to the current difference;

[0008] The driving circuit is configured to adjust the initial current according to the initial PID control parameter, so that the adjusted current has a constant pulse waveform;

[0009] The digital control circuit is further configured to output a speed control signal according to the standard speed;

[0010] The torch control circuit is configured to control the torch to rotate at a preset speed according to the speed control signal to weld the liner.

[0011] In one of the embodiments, the driving circuit is specifically configured to amplify the initial PID control parameter by a preset multiple to obtain a target PID control parameter, and adjust the initial current according to the target PID control parameter.

[0012] In one of the embodiments, the torch control circuit is further configured to obtain a pulse signal generated by a Hall sensor in the brushless deceleration motor of the torch;

[0013] The digital control circuit is further configured to output a rotation attribute control signal according to the pulse signal;

[0014] The torch control circuit is further configured to control the rotation position and / or rotation angle of the torch according to the rotation attribute control signal.

[0015] In one embodiment, the liner welding control circuit further includes a control signal isolation circuit connected to the digital control circuit;

[0016] The control signal isolation circuit is configured to electrically isolate the digital control circuit and the external analog circuit in a relay isolation manner, and the external analog circuit includes at least one of a motor control and drive circuit, a water cooling control circuit, a shielding gas control circuit, and a gun control circuit.

[0017] In one embodiment, the liner welding control circuit further includes an interrupt signal isolation circuit connected to the digital control circuit;

[0018] The interrupt signal isolation circuit is configured to obtain a welding interrupt signal;

[0019] The digital control circuit is further configured to control the torch to stop rotating through the torch control circuit according to the welding interrupt signal.

[0020] In one embodiment, the interrupt signal isolation circuit is further configured to electrically isolate the digital control circuit and the motor control and drive circuit in an optocoupler isolation manner.

[0021] In one embodiment, the digital control circuit is further connected to a human-machine interaction system;

[0022] The digital control circuit is further configured to obtain a standard current value through the human-machine interaction system.

[0023] In one embodiment, the initial current is applied to the liner by the main circuit, and the main circuit includes a full-bridge rectifier circuit, a filter circuit, a full-bridge inverter circuit, a high-frequency transformer, and a secondary rectifier circuit connected in sequence;

[0024] Among them, the full-bridge rectifier circuit is used to connect to the power grid, and the secondary rectifier circuit is used to connect to the liner to apply the initial current to the liner;

[0025] The drive circuit is specifically configured to drive the full-bridge inverter circuit according to the initial PID control parameters to adjust the initial current.

[0026] In a second aspect, a welding device is provided, which at least includes the liner welding control circuit described in the first aspect above.

[0027] In a third aspect, a welding control method is provided, which is used in the liner welding control circuit described in the first aspect above, and the method includes:

[0028] Sample the initial current of the liner tube to obtain a sampled current value;

[0029] Obtain the current difference between the sampled current value and the standard current value, and output the initial PID control parameters according to the current difference;

[0030] Adjust the initial current according to the initial PID control parameters so that the adjusted current has a constant pulse waveform;

[0031] Obtain a speed control signal according to the standard speed, and control the welding torch to rotate at a preset speed according to the speed control signal to weld the liner tube.

[0032] The beneficial effects brought by the technical solution provided by the embodiment of the present application at least include:

[0033] The liner tube welding control circuit of the embodiment of the present application includes a digital control circuit, and a current sampling feedback circuit, a drive circuit and a welding torch control circuit connected to the digital control circuit. Among them, the current sampling feedback circuit is used to sample the initial current of the liner tube to obtain a sampled current value, the digital control circuit is used to obtain the current difference between the sampled current value and the standard current value, and output the initial PID control parameters according to the current difference, the drive circuit is used to adjust the initial current according to the initial PID control parameters so that the adjusted current has a constant pulse waveform, the digital control circuit is also used to output a speed control signal according to the standard speed, and the welding torch control circuit is used to control the welding torch to rotate at a preset speed according to the speed control signal to weld the liner tube. In this way, by outputting the initial PID control parameters according to the current difference between the sampled current value and the standard current value to adjust the initial current, the adjusted current has a constant pulse waveform, realizing the fine control of the pulse waveform of the liner tube welding. In addition, outputting a speed control signal according to the standard speed to control the rotation of the welding torch realizes the fine control of the speed of the welding torch, thereby realizing the fine welding control of the liner tube welding as a whole. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a circuit schematic diagram of an exemplary liner tube welding control circuit in the embodiment of the present application;

[0036] Figure 2Schematic diagram of the interaction between an exemplary liner welding control circuit and an external circuit in an embodiment of the present application;

[0037] Figure 3 Schematic diagram of an exemplary current sampling feedback circuit in an embodiment of the present application;

[0038] Figure 4 Schematic diagram of an exemplary drive circuit (i.e., the DAC given current conditioning shown in Figure 2 and a torch control circuit (i.e., the DAC given speed conditioning shown in Figure 2 ) in an embodiment of the present application;

[0039] Figure 5 Schematic diagram of the interaction between an exemplary torch control circuit and a torch in an embodiment of the present application;

[0040] Figure 6 Schematic diagram of an exemplary control signal isolation circuit in an embodiment of the present application;

[0041] Figure 7 Schematic diagram of the interaction between an exemplary communication sub - circuit (i.e., the RS485 communication module shown in Figure 7 ) and a human - machine interaction system in an embodiment of the present application;

[0042] Figure 8 Schematic diagram of a welding control method in an embodiment of the present application. Detailed implementation manners

[0043] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0045] It can be understood that the terms "first", "second", etc. used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present application, the first resistor can be called the second resistor, and similarly, the second resistor can be called the first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0046] It can be understood that for the "connection" in the following embodiments, if there is a transfer of electrical signals or data between the connected circuits, modules, units, etc., it should be understood as "electrical connection", "communication connection", etc.

[0047] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprise / include" or "have" etc. specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0048] As a small-diameter part, the liner is widely used in various projects, such as in pipeline projects. Usually, its material is metal and it consists of an inner liner and an outer liner. During use, the inner liner and the outer liner need to be welded together to achieve welding repair.

[0049] The thicknesses of the inner liner and the outer liner are generally about one millimeter, and they are fine parts. In view of this, it has become an urgent problem to provide a liner welding control circuit that can achieve fine welding control for liner welding.

[0050] In view of this, the embodiment of the present application provides a liner welding control circuit. The liner welding control circuit includes a digital control circuit, and a current sampling feedback circuit, a drive circuit, and a welding torch control circuit connected to the digital control circuit. Among them, the current sampling feedback circuit is used to sample the initial current of the liner to obtain a sampled current value. The digital control circuit is used to obtain the current difference between the sampled current value and the standard current value, and output an initial PID control parameter according to the current difference. The drive circuit is used to adjust the initial current according to the initial PID control parameter so that the adjusted current has a constant pulse waveform. The digital control circuit is also used to output a rotational speed control signal according to the standard rotational speed. The welding torch control circuit is used to control the welding torch to rotate at a preset rotational speed according to the rotational speed control signal to weld the liner. In this way, by outputting the initial PID control parameter through the current difference between the sampled current value and the standard current value to adjust the initial current, the adjusted current has a constant pulse waveform, realizing fine control of the pulse waveform of liner welding. In addition, by outputting the rotational speed control signal according to the standard rotational speed to control the rotation of the welding torch, fine control of the rotational speed of the welding torch is realized, thereby overall realizing fine welding control of liner welding.

[0051] Hereinafter, the technical solutions of the embodiments of the present application will be introduced through some exemplary embodiments.

[0052] Please refer to Figure 1, which shows a schematic circuit diagram of a liner welding control circuit provided by an embodiment of the present application. As Figure 1 shown, the liner welding control circuit includes a digital control circuit, and a current sampling feedback circuit ( Figure 1 not shown), a drive circuit, and a torch control circuit connected to the digital control circuit.

[0053] First, the current sampling feedback circuit is introduced. The current sampling feedback circuit is used to sample the initial current of the liner to obtain a sampled current value.

[0054] The initial current of the liner is Figure 1 applied to the liner by the main circuit shown. As Figure 1 shown, the main circuit includes a full-bridge rectifier circuit, a filter circuit, a full-bridge inverter circuit, a high-frequency transformer, and a secondary rectifier circuit connected in sequence. Among them, the full-bridge rectifier circuit is used to connect to the power grid, and the secondary rectifier circuit is used to connect to the liner to apply an initial current to the liner.

[0055] The working principle of the main circuit is as follows: First, the full-bridge rectifier circuit converts the alternating current of the power grid into a DC bus voltage. The DC bus voltage filtered by the filter circuit passes through the full-bridge inverter circuit and is inverted into an AC square wave, and then through the secondary rectifier circuit, the AC square wave passing through the high-frequency transformer is rectified into direct current, that is, the initial current, and applied to the load (i.e., the liner).

[0056] Among them, the full-bridge inverter circuit is composed of switching tubes and their surrounding protection circuits, and the full-bridge switching tubes are alternately driven to conduct by an independent gate drive circuit.

[0057] In an embodiment of the present application, the current sampling feedback circuit is connected between the liner and the digital control circuit. The current sampling feedback circuit can sample the initial current of the liner to obtain a sampled current value. The sampled current value can be initial and feedback the sampled current value to the digital control circuit.

[0058] Next, the digital control circuit is introduced. The digital control circuit in the embodiment of the present application can adopt an ARM controller based on the CortexM4 core. Specifically, the STM32F405RGT6 chip can be adopted. The digital control circuit can also include a 3.3V voltage stabilization power supply module, an HSE crystal oscillator module, a manual reset module, a JTAG interface, and an auxiliary filter circuit. The embodiment of the present application adopts a fully digital modulation technology with an ARM processor as the core, which has the advantages of high control accuracy, fast response speed, strong anti-interference ability, and more efficient information processing and exchange ability. By embedding the FreeRTOS system to schedule and process various welding tasks in real time, it is beneficial to the digital modulation and refined control of the liner welding pulse waveform.

[0059] In the embodiment of the present application, the digital control circuit is used to obtain the current difference between the sampled current value and the standard current value, and output the initial PID control parameter according to the current difference.

[0060] The standard current value can be a current value with a constant pulse waveform input by the user. The digital control circuit calculates the current difference between the sampled current value and the standard current value, and calculates the initial PID control parameter according to the current difference through the PID (Proportion Integral Differential) algorithm. The initial PID control parameter can be the D / A output value calculated by the digital control circuit using the PID algorithm.

[0061] Next, the drive circuit is introduced. The drive circuit is used to adjust the initial current according to the initial PID control parameter, so that the adjusted current has a constant pulse waveform.

[0062] The drive circuit is driven by the D / A output of the digital control circuit to realize the inverse conversion of direct current. Specifically, the drive circuit can be used to drive the full-bridge inverter circuit in the main circuit according to the initial PID control parameter to adjust the initial current.

[0063] As an implementation manner, the drive circuit can control the duty cycle of the output current of the full-bridge inverter circuit according to the D / A output value to achieve the purpose of adjusting the initial current, and use the PID algorithm to control the stability of the output current of the main circuit, so as to accurately control the base value and peak value corresponding to the pulse waveform applied to the liner. Since during the welding process, it is desired that the initial current be as constant as possible, the embodiment of the present application can achieve a stable initial current through the above implementation manner, which is beneficial to improving the accuracy of welding control and realizing the closed-loop control of the output current of the main circuit in the welding operation.

[0064] In the embodiment of the present application, the digital control circuit is further used to output a rotation speed control signal according to the standard rotation speed, and the torch control circuit is used to control the torch to rotate at a preset rotation speed according to the rotation speed control signal to weld the liner.

[0065] The digital control circuit outputting the rotation speed control signal according to the standard rotation speed can be directly outputting the standard rotation speed as the preset rotation speed of the torch.

[0066] Among them, the standard rotation speed can be input by the user. For example, it can be 3 revolutions per minute, 4 revolutions per minute, etc. The standard rotation speed is the rotation speed matched with the initial current. Since during the welding process, it is necessary to ensure that the output current of the main circuit (i.e., the above initial current) matches the rotational movement of the torch, the embodiment of the present application sets the preset rotation speed of the torch through the standard rotation speed matched with the initial current. The torch control circuit is driven by the second D / A output of the digital control circuit to accurately control the rotation speed of the torch and realize the matching of the output current of the main circuit and the rotational movement of the torch.

[0067] Generally speaking, the liner welding control circuit in the above embodiments includes a digital control circuit, and a current sampling feedback circuit, a drive circuit, and a welding torch control circuit connected to the digital control circuit. Among them, the current sampling feedback circuit is used to sample the initial current of the liner to obtain a sampled current value. The digital control circuit is used to obtain the current difference between the sampled current value and the standard current value, and output an initial PID control parameter according to the current difference. The drive circuit is used to adjust the initial current according to the initial PID control parameter so that the adjusted current has a constant pulse waveform. The digital control circuit is also used to output a speed control signal according to the standard speed. The welding torch control circuit is used to control the welding torch to rotate at a preset speed according to the speed control signal to weld the liner. In this way, by outputting an initial PID control parameter based on the current difference between the sampled current value and the standard current value to adjust the initial current, the adjusted current has a constant pulse waveform, realizing the fine control of the liner welding pulse waveform. In addition, by outputting a speed control signal according to the standard speed to control the rotation of the welding torch, the fine control of the welding torch speed is realized, thereby realizing the fine welding control of the liner welding as a whole.

[0068] Based on Figure 1 the embodiments shown, see Figure 2 , Figure 2 FIG. is a schematic diagram of the interaction between an exemplary liner welding control circuit and an external circuit.

[0069] Figure 2 The ARM minimum system shown is Figure 1 the digital control circuit in the embodiments shown in Figure 2 The ADC current sampling conditioning shown is Figure 1 the current sampling feedback circuit in the embodiments shown in Figure 2 The DAC given current conditioning shown is Figure 1 the drive circuit in the embodiments shown in Figure 2 The DAC given speed conditioning shown is Figure 1 the welding torch control circuit in the embodiments shown in. Among them, the switching power supply can be an AC-DC switching power supply to provide 5V, ±15V, and 24V DC voltages to supply the digital control circuit and the rest of the hardware units.

[0070] Hereinafter, an exemplary implementation manner of the current sampling feedback circuit will be introduced.

[0071] See Figure 3 , which is a circuit diagram of an exemplary current sampling feedback circuit. As Figure 3As shown, the current sampling feedback circuit may include a 200A-class current Hall sensor of model HAS 200-P, a differential amplification circuit composed of differential amplifier U1 and its peripheral circuits, a low-pass filter circuit composed of chip U2 and its peripheral circuits, and a clamping circuit. The current Hall sensor, differential amplification circuit, low-pass filter circuit, and clamping circuit are connected in sequence.

[0072] Among them, the 200A-class current Hall sensor of HAS 200-P can linearly convert the current in the range of 0-200A into a voltage signal of 0-4V; the model of differential amplifier U1 can be AD629, which has performances such as low offset, low gain error drift, and high common-mode rejection ratio; the model of chip U2 can be OP177, which has performances such as low noise, low zero drift, and high-precision operational amplification.

[0073] In the embodiment of the present application, the drive circuit is specifically used to amplify the initial PID control parameter by a preset multiple to obtain the target PID control parameter, and adjust the initial current according to the target PID control parameter; the torch control circuit can also amplify the speed control signal by a preset multiple and then control the torch to rotate at a preset speed. The following will be described in conjunction with the circuit diagram.

[0074] Exemplarily, refer to Figure 4 , which is a circuit diagram of an exemplary drive circuit (i.e., Figure 2 shown DAC given current conditioning) and a torch control circuit (i.e., Figure 2 shown DAC given speed conditioning).

[0075] As Figure 4 shown, the D / A value (i.e., the initial PID control parameter) output by the digital control circuit is input to the voltage amplification circuit composed of U3 and its surrounding circuits, and the D / A value is proportionally amplified to drive the switching tubes of the full-bridge inverter circuit and the switching tubes of the torch control circuit.

[0076] Among them, chip U3 can use an amplification chip of model LF353. This chip has the performances of high input resistance and low output resistance, and has good voltage following and isolation effects; the proportionally amplified voltage value is connected to U4, which plays the roles of output voltage following and isolation between the front and rear stages; chip U4 can also use an amplification chip of model LF353.

[0077] Please continue to refer to Figure 4 , the D / A output corresponding to the drive circuit and the D / A output corresponding to the torch control circuit are respectively related to their respective amplification circuits. Figure 4 In

[0078] Figure 4 Among them, R404~R406 determine the amplification factor of the D / A output value of the motor speed. Specifically, the amplification factor is R404 = R405 / / R406.

[0079] During the actual implementation process, just set the resistors with corresponding resistance values according to the required amplification factor.

[0080] In the embodiment of the present application, the torch control circuit is further used to obtain the pulse signal generated by the Hall sensor in the brushless reduction motor of the torch; the digital control circuit is further used to output a rotation attribute control signal according to the pulse signal; the torch control circuit is further used to control the rotation position and / or rotation angle of the torch according to the rotation attribute control signal. The following will be described in conjunction with the circuit diagram.

[0081] Exemplarily, refer to Figure 5 , which is a schematic diagram of the interaction between an exemplary torch control circuit (i.e., Figure 5 the pulse modulation and isolation circuit shown) and the torch.

[0082] As Figure 5 shown, when the internal rotor of the brushless reduction motor in the torch rotates, it passes through three Hall sensors built in the brushless reduction motor of the torch, generating a rotor commutation pulse signal, and then a continuous pulse signal is generated by the Hall capture unit in the brushless reduction motor and output to the torch control circuit. Figure 6 Among them, R601 and R603 are current limiting resistors to protect the front end light emitting diodes of the optocouplers U8 and U9. Preferably, U8 and U9 are PC817, which have the function of electrical isolation. Correspondingly, R602 and R604 are also current limiting resistors to protect the timer module of the controller chip. After the pulse signal in the brushless reduction motor is modulated by the switch of the optocoupler, the signal input into the chip is also a pulse signal.

[0083] Channels 1 and 2 of the advanced timer TIM1 in the digital control circuit collect the pulse signal. Through the internal signal conversion and comparison of the timer, the accurate number of pulses obtained from the rotation of the motor rotor is obtained, so as to accurately judge the rotation angle of the brushless reduction motor and the rotation position of the rotor.

[0084] The digital control circuit outputs a rotation attribute control signal according to the pulse signal, and controls the rotation angle of the brushless reduction motor and the rotation position of the rotor to an ideal degree through the rotation attribute control signal. In this way, the torch control circuit controls the rotation position and / or rotation angle of the torch according to the rotation attribute control signal, realizing the precise control of the rotation angle of the brushless reduction motor and the rotation position of the rotor.

[0085] In the embodiment of the present application, a Hall capture unit is provided in the brushless deceleration motor. The number of captured pulses is compared with the preset pulse value in the program through the advanced timer inside the digital control circuit, so as to accurately control the rotation angle and rotation position of the brushless deceleration motor, thereby achieving the fine control of the cooperation between the current output of the welding machine and the rotation of the deceleration motor in the welding torch. Through the Hall capture unit in the brushless deceleration motor, the rotation angle and rotation position of the welding torch can be matched with the output of the welding power source, making the weld of the liner welding process perfect and the weld density good, achieving the purpose of liner welding repair and being more suitable for the repair working conditions of liner welding.

[0086] In one embodiment, the liner welding control circuit further includes a control signal isolation circuit connected to the digital control circuit; the control signal isolation circuit is used to electrically isolate the digital control circuit and the external analog circuit by means of relay isolation, and the external analog circuit includes at least one of a motor control and drive circuit, a water cooling control circuit, a shielding gas control circuit, and a gun pressing control circuit.

[0087] Please refer to Figure 2 , the control signal isolation circuit can be Figure 2 The two GPIOs shown, both of which are in the way of relay isolation, will be described below in conjunction with the circuit diagram.

[0088] Refer to Figure 6 , Figure 6 For an exemplary control signal isolation circuit (i.e., Figure 6 The circuit diagram of the integrated isolation chip circuit shown).

[0089] As Figure 6 shown, the control signal isolation circuit includes an integrated Darlington transistor IC, an optocoupler isolation chip, a switch LED signal lamp, and a relay; specifically, the integrated Darlington transistor IC refers to ULN2003A, and this integrated chip is a 7-channel inverter. When the digital control circuit outputs a high level and inputs it to ULN2003A through the GPIO pin, the output is a low level. Through the cooperation of the optocoupler, the optocoupler is turned on; specifically, the optocoupler isolation chip refers to PC817. After the front-end diode is turned on, the optocoupler is turned on, and the electrical signal passes through the relay circuit to control the switch of the relay, thereby controlling the module connected to the relay circuit, such as the gas protection of the welding torch, the water circulation, and the switch of the motor required during liner welding.

[0090] Furthermore, the control signal isolation circuit is centered on the U6 high-linearity analog optocoupler. Preferably, U6 is the high-linearity optocoupler chip HCNR201, which contains a high-performance AIGaAs LED and two highly matched photodiodes. According to the matching of the front-end resistor R501 and the back-end resistors R503 and R504, linear input and output of voltage can be achieved.

[0091] The front-stage and rear-stage operational amplifiers in the control signal isolation circuit are powered by completely independent power supplies, which play a role in isolating interference, that is, the power supplies of chips U5 and U6 are different. Preferably, LF353 operational amplifier chips are selected for U5 and U6. At the same time, different power supplies provide different grounds. The grounds at both ends of U6 are GND1 and GND2 respectively, realizing the isolation between digital signals and analog signals, achieving absolute isolation of signals before and after the chip. The front-stage and rear-stage circuits are isolated by means of an optocoupler, which can efficiently shield the interference generated between the digital circuit and the backend analog circuit, and improve the anti-interference ability of the control system.

[0092] The embodiment of the present application adopts highly integrated isolation measures, effectively avoiding signal interference between the analog circuit and the digital circuit, and improving the anti-interference ability of the control system.

[0093] In one embodiment, the liner welding control circuit further includes an interrupt signal isolation circuit (such as the optocoupler isolation module shown in Figure 2 ) connected to the digital control circuit. This interrupt signal isolation circuit is used to obtain the welding interrupt signal input by the user; the digital control circuit is further used to control the welding torch to stop rotating through the torch control circuit according to the welding interrupt signal.

[0094] During the implementation process, there will be unexpected situations where the welding operation needs to be stopped urgently. The embodiment of the present application realizes the emergency stop of the entire liner welding control circuit through the interrupt signal isolation circuit, improving the practicability.

[0095] This interrupt signal isolation circuit is also used to electrically isolate the digital control circuit and the motor control and drive circuit by means of optocoupler isolation.

[0096] The motor control and drive circuit is the circuit in the brushless reduction motor in the welding torch and is close to the welding power supply, which will cause high-frequency interference to the digital control circuit. The embodiment of the present application eliminates the high-frequency interference of the welding power supply to the digital system through the interrupt signal isolation circuit.

[0097] The embodiment of the present application adopts highly integrated isolation measures at both the input end and the output end of the digital control circuit. The methods include relay isolation, optocoupler isolation, etc., effectively avoiding signal interference between the analog circuit and the digital circuit, and further improving the stability and reliability of the liner welding system.

[0098] In one embodiment, the digital control circuit is also connected to the human-machine interaction system. Exemplarily, the digital control circuit includes a communication sub-circuit, and the digital control circuit is connected to the human-machine interaction system through this communication sub-circuit.

[0099] Exemplarily, refer to Figure 7 , Figure 7An interaction schematic diagram of an exemplary communication sub-circuit (i.e., the RS485 communication module shown in Figure 7 ) and a human-machine interaction system.

[0100] The digital control circuit is also used to obtain the standard current value through the human-machine interaction system.

[0101] As shown in Figure 7 , the human-machine interaction system connects the human-machine interaction touch screen and the RS485 communication module (i.e., the communication sub-circuit) of the digital control circuit through differential signal twisted pairs.

[0102] Exemplarily, the power input module in the human-machine interaction system can select a switching power supply to supply 5V and 24V DC power to provide power for the RS485 transceiver chip and the industrial-grade touch screen; the isolation input and output modules for communication are implemented by U10 and its surrounding circuits; specifically, U10 can be an RS485 transceiver chip of model SP3485, which has performances such as low power consumption, single power supply, and signal isolation.

[0103] The digital control circuit determines the master-sending and slave-receiving relationship between the digital control circuit and the touch screen by programming the transceiver modes of the corresponding pins. The matching of R701 to R703 is used to ensure that the SP3485 is in an idle state when there is no connection, providing network failure protection and improving the reliability of the RS485 node and the network.

[0104] In the embodiment of the present application, the industrial-grade touch screen of the human-machine interaction system has functions such as obtaining input data and receiving and displaying data in real time; specifically, an industrial human-machine interaction interface touch screen of model Sucong HC-SuK3070i can be selected, which has advantages such as user-defined communication protocols and IDE user interface custom editing.

[0105] Before the liner welding, the user-defined target welding parameters can be sent to the digital control circuit through the human-machine interaction system, and the digital control circuit receives the data and outputs the corresponding electrical signal value according to the target welding parameters.

[0106] In the embodiment of the present application, the human-machine interaction system uses differential signals for communication, enhancing the anti-interference ability during the modulation process and improving the anti-interference ability during communication, with good stability and reliability; using an industrial-grade touch screen as the main body of the human-machine interaction module provides flexible welding parameter design and visual display of welding parameters, which is beneficial to convenient operation before and during welding.

[0107] In general, the above embodiment adopts a powerful and low-cost ARM core controller, and realizes signal input and output isolation through hardware control circuits arranged around the ARM chip. It uses highly integrated isolation measures to effectively avoid signal interference between analog circuits and digital circuits, and all digital human-computer interactions are also realized through the touch screen, which improves the intelligence of the entire system.

[0108] In one embodiment, a welding device is provided, which comprises at least a liner welding control circuit as described in any of the above embodiments.

[0109] The welding equipment also includes the FreeRTOS real-time operating system and the functional modules implemented by the ARM library functions. The FreeRTOS real-time operating system is used as the embedded kernel of the core controller to build the liner welding control system platform. The core controller resources are used through task division and scheduling, ensuring the real-time and flexibility of the system operation. The functional modules implemented by the ARM library functions include the welding process control, A / D conversion, D / A conversion, PID algorithm operation, TIM timing, digital control of output waveforms, and communication between various parts of the liner welding control system.

[0110] In general, the ARM chip has a multifunctional digital wave control software system running on the FreeRTOS embedded real-time operating system. It can use the core controller resources through task division and scheduling, ensuring the real-time and flexibility of system operation. It realizes welding process control, A / D conversion, D / A conversion, PID algorithm operation, TIM timing, digital control of output waveform and communication between various parts through the ARM chip library function.

[0111] Other specific limitations and beneficial effects of the welding equipment can be found in the above embodiments and will not be described in detail here.

[0112] In one embodiment, see Figure 8 , a welding control method is provided, the welding control method is used in the liner welding control circuit as described in any of the above embodiments, the method comprising the following steps:

[0113] Step 801, sampling the initial current of the liner to obtain a sampled current value;

[0114] Step 802, obtaining a current difference between the sampled current value and the standard current value, and outputting an initial PID control parameter according to the current difference;

[0115] Step 803, adjusting the initial current according to the initial PID control parameters so that the adjusted current has a constant pulse waveform;

[0116] Step 804: Obtain a rotational speed control signal according to the standard rotational speed, and control the welding torch to rotate at a preset rotational speed according to the rotational speed control signal, so as to weld the liner tube.

[0117] For the specific limitations and beneficial effects of the welding control method, reference can be made to the embodiments of the above-mentioned liner tube welding control circuit, which will not be elaborated here.

[0118] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0119] The above embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A liner welding control circuit, characterized in that, It includes a digital control circuit, and a current sampling feedback circuit, a drive circuit, and a torch control circuit connected to the digital control circuit; The current sampling feedback circuit is used to sample the initial current of the liner tube to obtain a sampled current value; The digital control circuit is used to obtain the current difference between the sampled current value and the standard current value, and output an initial PID control parameter according to the current difference; The drive circuit is used to adjust the initial current according to the initial PID control parameter so that the adjusted current has a constant pulse waveform; The digital control circuit is further used to output a speed control signal according to the standard speed; The torch control circuit is used to control the torch to rotate at a preset speed according to the speed control signal to weld the liner tube; The torch control circuit is further used to obtain a pulse signal generated by a Hall sensor in the brushless deceleration motor of the torch; The digital control circuit is further used to output a rotation attribute control signal according to the pulse signal; The torch control circuit is further used to control the rotation position and / or rotation angle of the torch according to the rotation attribute control signal.

2. The liner welding control circuit according to claim 1, wherein The drive circuit is specifically used to amplify the initial PID control parameter by a preset multiple to obtain a target PID control parameter, and adjust the initial current according to the target PID control parameter.

3. The liner welding control circuit according to claim 1, characterized in that, The liner tube welding control circuit further includes a control signal isolation circuit connected to the digital control circuit; The control signal isolation circuit is used to electrically isolate the digital control circuit and an external analog circuit in a relay isolation manner, and the external analog circuit includes at least one of a motor control and drive circuit, a water cooling control circuit, a shielding gas control circuit, and a gun control circuit.

4. The liner welding control circuit according to claim 1, wherein The liner tube welding control circuit further includes an interrupt signal isolation circuit connected to the digital control circuit; The interrupt signal isolation circuit is used to obtain a welding interrupt signal; The digital control circuit is further used to control the torch to stop rotating through the torch control circuit according to the welding interrupt signal.

5. The liner welding control circuit according to claim 4, wherein The interrupt signal isolation circuit is further used to electrically isolate the digital control circuit and the motor control and drive circuit in an optocoupler isolation manner.

6. The liner welding control circuit according to claim 1, wherein The digital control circuit is further connected to a human-machine interaction system; The digital control circuit is further used to obtain the standard current value through the human-machine interaction system.

7. The liner welding control circuit according to claim 1, wherein The initial current is applied to the liner tube by a main circuit, and the main circuit includes a full-bridge rectifier circuit, a filter circuit, a full-bridge inverter circuit, a high-frequency transformer, and a secondary rectifier circuit connected in sequence; Wherein, the full-bridge rectifier circuit is used to connect to the power grid, and the secondary rectifier circuit is used to connect to the liner tube to apply the initial current to the liner tube; The drive circuit is specifically used to drive the full-bridge inverter circuit according to the initial PID control parameter to adjust the initial current.

8. A welding device, characterized in that, It at least includes the liner tube welding control circuit according to any one of claims 1-7.

9. A welding control method, characterized in that, For the liner tube welding control circuit according to any one of claims 1-7, the method includes: Sample the initial current of the liner tube to obtain a sampled current value; Obtain the current difference between the sampled current value and the standard current value, and output an initial PID control parameter according to the current difference; Adjust the initial current according to the initial PID control parameter so that the adjusted current has a constant pulse waveform; Obtain a speed control signal according to the standard speed, and control the welding torch to rotate at a preset speed according to the speed control signal to weld the liner tube; Obtain the pulse signal generated by the Hall sensor in the brushless reduction motor of the welding torch; Output a rotation attribute control signal according to the pulse signal; Control the rotation position and / or rotation angle of the welding torch according to the rotation attribute control signal.

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