Control panel of inverter welding and cutting machine adopting five-welding and one-cutting method

Abstract

The utility model relates to a control panel of an inverter welding and cutting machine adopting a five-welding and one-cutting method, the control panel is mounted on a front panel of a product, and a control circuit part of the control panel mainly comprises a power supply circuit; an output voltage sampling, signal conversion processing and filtering control circuit; electromagnetic gas valve control, wire feeder output connection, a wire feeder voltage feedback circuit and the like; eight external connection sockets are arranged on the control panel and can be connected with the outside through plugs of the sockets, five methods of MIG welding, MAG welding, FLUX welding, MMA welding and TIG welding and a CUT plasma arc cutting method can be selected and achieved through a single key, and welding parameter coordination or linkage control can be achieved during gas shielded welding and FLUX welding. The control panel is simple in circuit, complete in control function and easy in external connection, the problem that the welding and cutting machine has more use functions is solved, the welding and cutting performance of a product is improved, and the application range of the product is expanded.

Description

Technical Field

[0001] The invention relates to a control panel of an inverter welding and cutting machine with five welding and one cutting method, belonging to the technical field of inverter welding machines. Background Art

[0002] In the past, inverter gas shielded welding machines with single-phase power supply in the domestic and foreign markets could usually only perform MIG and MAG gas shielded welding (hereinafter referred to as MIG and MAG welding), and their rated current was 120~200A. With the development of FLUX flux-cored wire manufacturing technology, there are more and more types of welding wires, including not only gas-shielded FLUX welding wires (such methods can be classified as gas shielded welding), but also gas-free or self-shielded FLUX welding wires. This type of welding wire was rarely used in the past, especially in the fields of household use, because there were few specifications, mainly 15~20Kg / reel, and the price was expensive. However, in recent years, the specifications of FLUX welding wires have not only increased, but also 0.4~5Kg / reel, and the price has also decreased. It has achieved rapid development in the fields of household use. At the same time, inverter welding machines that can perform MIG and MAG welding and are equipped with output polarity conversion functions and can weld with gas-free or self-shielded FLUX welding wires (hereinafter referred to as FLUX welding) have also developed rapidly.

[0003] In addition, with the development of microprocessor technology, its applications are increasing, and the price of chips is relatively cheap, which provides a solid foundation for the application of this technology in the field of welding machine manufacturing. Up to now, the welding machine industry has been in an important development period of technological upgrading, and one of the main directions of product development is to use digital control technology to achieve multifunctional and high-performance welding or cutting operations of products.

[0004] The more functions a multifunctional welding machine has, for example, a welding machine that can perform MMA manual welding in addition to MIG, MAG and FLUX welding, will have a more complex circuit and structure if implemented using analog circuits. Its operation interface and operation mode, as well as welding performance and manufacturing costs, will also be affected and restricted by many unfavorable factors. However, if implemented using a digital circuit with a microprocessor as the core, the previous unfavorable aspects have been greatly changed. This is also one of the important reasons for the rapid development of multifunctional welding machines controlled by microprocessors in recent years.

[0005] At present, there are more and more microprocessor-controlled welding machines with MIG, MAG, FLUX and MMA welding functions. This has greatly improved the functions, welding performance, display and operation interface of such welding machines, making them the mainstream products of development. In addition, developers are also actively researching and exploring multifunctional welding and cutting machine products that can perform air plasma cutting in addition to the above welding functions. However, it is technically difficult to develop products with more functions based on microprocessor control technology. Problems in control circuit design and software programming need to be solved.

[0006] The present invention is one of the technical achievements developed under the above background. The present invention relates to a control panel of an inverter welding and cutting machine with five welding and one cutting methods, which is installed on the front panel of the product. A single button can be used to select and implement five welding methods, namely, MIG and MAG welding, FLUX welding, MMA welding and TIG welding, as well as CUT air plasma arc cutting (hereinafter referred to as plasma arc cutting or CUT cutting) method, and welding parameters can be coordinated or linked during gas shielded welding and FLUX welding. When selecting, there are corresponding indicator lights for indication, and welding or cutting parameters can also be displayed. The user operation interface is friendly, which facilitates the user's welding or cutting operation control and reduces the difficulty of user use. The circuit composition of the control panel of the present invention is simple, the control function is clear and complete, and the external connection is simple. Through its application, the problem of the product having more use functions can be solved, the welding and cutting performance of the product can be improved, and the application range of the product can be expanded. Using this control panel, in conjunction with the circuits and components of other parts, a multifunctional welding and cutting machine can be made. For example, it can be made into a multifunctional inverter welding and cutting machine with a power supply of 220-240V, a frequency of 50 or 60Hz, a rated current of 160A for MIG / MAG / FLUX welding, MMA welding and TIG welding, and a rated current of 40A for CUT cutting. Utility Model Content

[0007] The present invention relates to a control panel of an inverter welding and cutting machine with five welding methods and one cutting method, which is installed on the front panel of the product. A single button can be used to select and implement five welding methods, namely MIG and MAG welding, FLUX welding, manual welding and argon arc welding, as well as a cutting method. The welding parameters can be coordinated or linked during gas shielded welding and FLUX welding. At the same time, there are corresponding indicator lights for indication, and the welding or cutting parameters can also be displayed, so that the user operation interface is friendly. This simplifies the operation, greatly facilitates the user's welding or cutting operation control, and reduces the difficulty of user use. The control panel of the present invention has a simple circuit composition, clear and complete control functions, and simple external connections. Through its application, the problem of the product having more use functions can be solved, the welding and cutting performance of the product can be improved, and the application range of the product can be expanded. The control panel can be used in conjunction with the circuits and components of other parts to make a multifunctional welding and cutting machine.

[0008] The welding and cutting machine control board of the present invention is characterized in that: its control circuit part mainly includes 13 sub-circuits, specifically 5V power supply and Vdriv power supply circuit; output voltage sampling, signal conversion processing and filtering control circuit; electromagnetic valve control, wire feeder output connection, wire feeder voltage feedback circuit; voltage given signal circuit and current given signal circuit; overcurrent protection control and LED2 indication circuit; rectification, resistor network and filtering circuit; IGBT low-voltage side drive circuit; current parameter display and LED indication circuit; wire feeder drive circuit; cutting gun switch detection, cutting arc high-frequency control, cutting output The circuit of the gas valve control part for conversion control and cutting; the gas shielded welding gun switch detection circuit; the overheat protection signal detection circuit; the MCU microprocessor control circuit; the control board is equipped with eight external connection sockets, CN1, CN2, CN3, CN4, CN5, CN6, CN8, and CN9, which can be connected to the outside through the plugs of each socket. Among them, the CN2 socket is used to connect the program burner to burn the control program of the microprocessor; the CN1 socket is used to connect the power supply of the wire feeder control circuit, such as connecting to a secondary winding of the main transformer in the inverter welding and cutting machine; the 1st and 2nd pins of the CN3 socket are connected to ... The pins of CN3 are connected to the primary of the IGBT drive transformer through its plug and its control line. The pin 3 of CN3 is connected to 15V, the pin 5 of CN3 is connected to the 15V ground, and the pins 6 and 7 of CN3 are connected in series to the output ends of the current detection transformer in the primary circuit of the main transformer; the pins 1 and 3 of the CN4 socket are connected to the switch control line of the gas shielded welding gun; the pins 1 and 2 of the CN5 socket are respectively connected to the M+ and M- ends of the wire feeding motor, which is a component of the wire feeding mechanism in the welding and cutting machine; the pins 3 and 4 of CN5 are respectively connected to the positive and negative polarity ends of the electromagnetic valve used in the gas shielded welding; the pin 2 of the CN6 socket is connected to 1 5V, its 3rd pin is grounded; the 1st and 2nd pins of CN6 are connected to the switch control signal cut-trig-KZ of the cutting gun; the 4th pin of CN6 is the high-frequency control cut-HF-KZ signal during cutting; the 5th pin of CN6 is the cut-jdq-KZ signal of the relay output conversion control during cutting; the 6th pin of CN6 is the cut-gas-KZ signal of the electromagnetic valve control of the compressed air during cutting; the 4th pin and the 5th pin (connected to 15V) of the CN8 socket are connected to the overheat protection WKQ thermostat control line inside the welding machine; the 1st and 2nd pins of the CN9 socket are respectively connected to the U of the welding output circuit 2f The two ends of the output voltage sampling signal, where pin 1 is the positive polarity end of the signal.

[0009] The 5V power supply and Vdriv power supply circuit of the control board of the present invention, wherein the 5V power supply circuit is composed of a 15V power supply, an integrated voltage stabilizer, a capacitor and an electrolytic capacitor, and a 5V power supply can be obtained; the 15V power supply comes from other circuits of the welding machine, such as a switch power supply circuit, etc., and it is introduced into the control board through the 3rd pin of CN3 on the control board; the other part is the Vdriv power supply circuit, whose input power comes from the CN1 plug on the control board, and it is connected to the output end of a secondary winding of the inverter main transformer in the welding machine through a connecting line. The Vdriv power supply is supplied to the electromagnetic valve control circuit and the wire feeder drive circuit to work.

[0010] The sampling, signal conversion processing and filtering control circuit of the output voltage of the control board of the present invention is connected to the welding output end of the machine through the CN9 plug and its control line to obtain the voltage feedback signal U 2f , this signal will participate in the feedback control of some welding methods.

[0011] The electromagnetic valve control, wire feeder output connection, and wire feeder voltage feedback circuit of the control board of the present invention are mainly composed of a CN5 socket, a Vdriv DC power supply, resistors R5~R10, R88, a capacitor C5, a diode D1, and an N-channel MOS tube Q12. Pin 1 of CN5 is connected to the positive polarity end of the wire feeding motor, and pin 2 of CN5 is connected to the negative polarity end of the wire feeding motor. When there is an output voltage between M+ and M-, the wire feeding motor runs and wire feeding can be achieved, otherwise the wire feeding machine will not rotate or feed wire. For the wire feeding voltage feedback circuit, it is mainly composed of resistors R5~R7 and capacitor C5; the wire feeding voltage feedback signal spd is taken from the voltage divided signal at both ends of the motor, and the signal is transmitted to pin 41 of the microprocessor U1B to participate in wire feeding control. For the electromagnetic valve control circuit, pin 3 of CN5 is connected to the positive polarity end of the electromagnetic valve (for gas shielded welding), and its pin 4 is connected to the negative polarity end of the valve. The Gdriv signal is the output control signal from pin 44 of U1B. When the Gdriv control signal turns on the field effect tube Q12, the electromagnetic valve connected to the CN5 socket can be activated. Otherwise, the electromagnetic valve is closed. This can realize the on and off control of the shielding gas. In addition, through the setting of the control software, the early gas supply and delayed gas blocking time control during gas shielded welding can be realized, and these times can be set or modified by the control software.

[0012] The voltage given signal circuit and current given signal circuit of the control board of the present invention mainly include a 5V power supply, a variable potentiometer VR2, a diode D25, resistors R76, R76, capacitors C23 and C24; the adj2 signal is connected to the 37th pin of the microprocessor U1B part, and the adj2 signal is the output voltage given signal during MIG, MAG or FLUX welding. The current given signal circuit includes 5V, a variable potentiometer VR1, a diode D20, resistors R60, R61, capacitors C20 and C18; the adj1 signal end is connected to the 22nd pin of U1B, and the adj1 signal is the output current given signal of MMA, TIG welding and CUT cutting, or the output current given signal during MIG, MAG or FLUX welding.

[0013] The overcurrent protection control and LED2 indication circuit of the control board of the present invention mainly consists of a 15V power supply, resistors R37-R43, capacitors C16 and C100, diodes D11 and D12, indicator light LED2, NPN transistor Q5, and PNP transistor Q4; i f1 The signal comes from the rectifier, resistor network and filter circuit. The input of the circuit is connected to the 6th and 7th pins of CN3, which are connected to the detection signal of the primary current of the main transformer. This current detection signal is obtained after rectification, resistor network transformation and capacitor filtering. When an overcurrent phenomenon occurs, LED2 lights up to indicate that an overcurrent phenomenon has occurred. At the same time, OCK1 and OCK2 overcurrent protection control signals can be obtained. The OCK2 signal is connected to the 13th pin of the microprocessor U1B, and the OCK1 signal is connected to a control end of the IGBT low-voltage side drive circuit. When the microprocessor receives the OCK2 signal, it can turn off the output of the PWMe pulse output enable control signal of the 19th pin of U1B, and the OCK1 signal controls the IGBT low-voltage side drive circuit, so that the IGBT drive circuit stops outputting PWM signals, and the inverter main circuit stops working, making it impossible to weld or cut. When the overcurrent phenomenon is relieved, the LED2 indicator light will go out before welding or cutting operations can be performed again.

[0014] The present invention controls the rectifier, resistor network and filter circuit of the board. In the circuit, a current detection transformer is provided in the primary circuit of the main transformer, which is used to detect the primary current. The detection output signals CT1 and CT2 are rectified by a bridge rectifier circuit composed of diodes D3, D4, D13 and D14, and then filtered by a resistor network and capacitor at the rear stage to obtain i and t. f1 Signal and i f2 Signal. i f1 The signal is connected to the overcurrent protection control and LED2 indication circuit, and participates in the control of overcurrent protection; i f2 The signal is connected to pins 20 and 21 of the microprocessor U1B. The microprocessor can f2The current feedback analog quantity is converted into digital quantity, and finally the digital quantity of the current feedback signal is obtained, which is used as the current negative feedback signal to participate in output control.

[0015] The IGBT low-voltage side drive circuit of the control board of the present invention is composed of the primary of the drive transformer (inside the welding machine, connected to the 1st and 2nd pins of CN3, attached Figure 6 The drive transformer and its primary are not drawn in the figure), Q1 and Q2 drive chips (NCE4614), MOS tube drive UB1 chip (FL560), NPN transistors Q3 and Q8, diodes D5~D10, resistors R1, R11~R15, R21~R27, capacitors C7~C8 and C25, 15V power supply, as well as PWM and OCK1 control signals, and CN3 socket; the PA end is connected to the 12th pin of the MCU microprocessor U1B; the PB end is connected to the 11th pin of U1B; the PWMe end is connected to the 19th pin of U1B; the OCK1 end is connected to the overcurrent protection control and LED2 indication circuit; the OCK1 end is the overcurrent protection control signal end. When the control circuit detects an overcurrent phenomenon, OCK1 is a high-level signal, which can turn on Q3 and Q8, and pull the 2nd pin (HIN end) and 3rd pin (LIN end) of UB1. To a low level, thereby turning off the pulse signal output by UB1, so that the IGBT tube in the inverter circuit will not be turned on, thereby realizing overcurrent protection control; the PWMe end is the IGBT drive signal output enable control signal end. When this end is a high-level signal, the 2nd pin (HIN end) and the 3rd pin (LIN end) of UB1 can be pulled to a low level, thereby turning off the pulse signal output by UB1, so that the IGBT tube in the inverter circuit is not turned on. On the contrary, when the PWMe end is a low level, UB1 can have the conditions to output the drive pulse signal, so that the IGBT tube in the inverter main circuit can be turned on conditionally; the PA and PB ends are the PWM (pulse width modulation signal) output control ends output by the microprocessor U1B. Pins 1 and 2 of the CN3 socket on the control board are connected to the attached through the plug and its control line. Figure 3 The IGBT in the drive transformer is the primary side.

[0016] The current parameter display and LED indication circuit of the control board of the present invention mainly includes an SMG digital tube display meter U3 (5631A), a digital tube display drive control chip U2 (TM1652), and seven LED indicator lights, including OH overheating D33, MMA welding D24, TIG welding D29, CUT cutting D32, MAG welding D21, MIG welding D28, and FLUX welding D27 indicator lights; o1~o8 of U3 are connected to the corresponding connection points of U2, wherein o1~o5 are also connected to the anodes of D27, D28 and D33, D29, D24 and D32, D21 respectively, and the cathodes GR5 of D32 and D33 are connected to the corresponding connection points of U2. The cathodes GR4 of D21, D24, D27, D28 and D29 are connected to the corresponding connection points of U2. GR1, GR2 and GR3 of U3 are respectively connected to the corresponding connection points of U2. The 16-pin data of U2 is a control signal. Which indicator light is on depends on the level of o1~o5 signals and the level state of GR4 and GR5 signals, which depends on the data control signal sent by the microprocessor. At the same time, the current parameter displayed by the digital tube also depends on the data control signal. Under the control of the microprocessor, the corresponding indicator light can be lit according to the operation of the SW1 method selection button and the output current size signal obtained to indicate the user's selection operation, which also determines the control of different welding or cutting methods and the display of output current parameters.

[0017] The control panel of the present invention, viewed from the outside of the welding machine, is provided with a current display meter, a method selection button, seven indicator lights, a voltage adjustment potentiometer, and a current adjustment potentiometer on the top of the operation control panel. The seven indicator lights include an OH overheat indicator light and six method indicator lights, namely, MMA welding, MIG welding, MAG welding, FLUX welding, TIG welding, and CUT cutting indicator lights. Through the method selection button, one of the six methods can be selected respectively, and when selecting, the corresponding indicator light is lit, so it is more intuitive for the user to select the operation. When selecting MMA, TIG welding, and CUT cutting, the welding or cutting current can be adjusted by the current adjustment potentiometer; when selecting MIG, MAG, or FLUX welding, the adjustable parameters are wire feeding speed or current, voltage, and the method adopted is a collaborative or linkage adjustment method, rather than an independent or separate parameter adjustment method. Collaborative or linkage adjustment means that when the welding voltage is adjusted, the welding current automatically changes, or when the welding current is adjusted, the welding voltage automatically changes. The result of this collaborative or linkage adjustment is set by the developer based on a large amount of accumulated welding operation knowledge, so the operator is not required to have high relevant knowledge and skills. In other words, this method can greatly facilitate the operator to adjust the welding parameters and is more convenient to use, especially for beginners in welding operations, it has more practical significance.

[0018] The functions of the display and operation control circuit are: 1) to realize the selection and control of five welding methods, namely MMA, TIG, MIG, MAG and FLUX welding, and one CUT cutting method; 2) to realize the adjustment and control of the respective welding parameters under different methods; 3) to realize the display of various states, including the indication of different methods; overheating indication; current display.

[0019] 9) The wire feeder drive circuit is mainly composed of MOS tube driver UB2 chip, N-channel MOS tubes Q11 and Q13, diode D2, capacitors C10 and C15, Vdriv and 15V power supply, resistors R29, R30, R32, R35, R36, R48, and Mdriv and Mbrake control signals of microprocessor U1B. The wire feeder motor is connected between M+ and M-. The Mdriv signal comes from pin 45 of U1B; the Mbrake end is the wire feeder stop control signal end, which comes from pin 43 of U1B. R36 and R48 are resistors with large wattage, which are used for motor braking; the Mdriv signal controls the Q11 tube after passing through the subsequent circuit; the speed of the wire feeder motor is controlled by controlling the on and off time of the Q11 tube; the Mdriv signal is determined by the wire feeder speed set value signal and the spd wire feeder voltage feedback signal, and the digital PI (proportional integral) operation control method is used in the microprocessor to control the wire feeder speed. For example, the wire feeding speed can be changed by changing the given value of the wire feeding speed, which determines the wire feeding speed or current control during MIG / MAG or FLUX welding; when the Mdriv signal is changed, Q11 can be in an on-off state. Different Mdriv control signals will obtain different motor armature voltages, so the motor speeds are different. In addition, when the spd wire feeding voltage feedback signal changes, or when certain factors change and affect the change of the feedback signal, it will not have a significant impact on the wire feeding speed, and can achieve the purpose of stabilizing the wire feeding speed and control. This is the working principle of the present invention to achieve the regulation of wire feeding speed and negative feedback control. For the wire feeding stop brake or energy consumption brake control circuit, it is to control whether the parallel brake resistors R36 and R48 are connected to the control circuit of the wire feeding motor. When the Mbrake signal terminal outputs a stop conveying control instruction, the output of the UB2 chip can turn on Q13, while Q11 is turned off, so that R36 and R48 are connected to the motor circuit and the wire feeding control is stopped. When R36 and R48 are connected to the motor circuit, the energy of the wire feeding motor can be quickly consumed to achieve energy consumption braking, which prevents the welding wire from rushing out of the welding gun's conductive nozzle too long and entering the molten pool when welding stops, and the so-called wire sticking phenomenon occurs. In addition, if the welding wire extends too long from the conductive nozzle, it will also affect the arc control of the next gas shielded welding, which needs to be avoided.

[0020] 10) The circuits for cutting gun switch detection, cutting arc ignition high frequency control, cutting output conversion control, and cutting gas valve control are mainly composed of 5V and 15V power supplies, resistors R50, R63, R77~R86, capacitor C30 and electrolytic capacitor C31, NPN transistors Q9, Q10, Q14, Q15, and CN6 socket. Pin 2 of CN6 is connected to 15V, its pin 3 is grounded, and pins 1 and 2 of CN6 are connected to the switch control signal cut-trig-KZ line of the cutting gun.

[0021] The cut-trig signal in the circuit is the state detection signal of the cutting gun switch, which is connected to the 42nd pin of the MCU microprocessor controller U1B. During the cutting operation, when the cutting gun switch is not closed, the cut-trig-KZ signal is low, Q15 is cut off or not conducting, and the cut-trig signal is high; when the cutting gun switch is closed, the cut-trig-KZ signal is high, Q15 is conducting, and the cut-trig signal is low. The microprocessor can know whether the cutting gun switch is closed by detecting the high and low levels of the cut-trig signal level, and perform corresponding control. For example, high-frequency control during cutting; relay output conversion control; electromagnetic valve control of compressed air output, etc., see the further description below.

[0022] The 4th pin of the CN6 socket is the high-frequency control signal cut-HF-KZ output during cutting; whether the cut-HF-KZ signal is low-level or high-level depends on the k-HF control signal, which is connected to the 40th pin of U1B. When it is detected that the switch of the cutting gun is closed, the microprocessor can output a high-level k-HF signal to turn on Q10, and the output high-frequency control signal cut-HF-KZ is low-level. By using the high-frequency control circuit connected thereto (not in the circuit part of this control board, but inside the machine, which will be further explained in the subsequent application examples of the present invention, and will not be explained here in detail), the machine can generate an arc-starting high-frequency high-voltage signal, thereby igniting the arc between the cutting gun and the workpiece.

[0023] Pin 5 of the CN6 socket is the control signal cut-jdq-KZ for the relay output conversion during cutting; whether the cut-jdq-KZ signal is low level or high level depends on the k-jdq signal, which is connected to pin 39 of U1B. When it is detected that the cutting gun switch is closed, the microprocessor can output a high-level k-jdq signal to turn on Q9, and the output cut-jdq-KZ is low level. The cutting output conversion relay control circuit connected thereto (not in the circuit part of this control board, but inside the machine, will be further explained in the subsequent application examples of the present invention, and will not be explained in detail here.) can enable the machine to realize the output conversion of the inverter main circuit part (Note: For the multi-function machine of the present invention, the output requirements of the inverter main circuit are different during welding and cutting. For example, the output current is large and the output voltage is low (below tens of volts) during welding; while during cutting, on the contrary, the output current is small and the output voltage is high (more than 90 volts, or even higher). Therefore, it is necessary to use a relay to control the output conversion. This will be further explained in the subsequent application examples of the present invention, and will not be explained in detail here.), thereby providing output guarantee for igniting the high-voltage and low-current arc between the cutting gun and the workpiece.

[0024] The 6th pin of the CN6 socket is the electromagnetic valve control signal cut-gas-KZ output by the compressed air during cutting; whether the cut-gas-KZ signal is low or high depends on the k-gas signal, which is connected to the 38th pin of U1B. When it is detected that the switch of the cutting gun is closed, the microprocessor can output a high-level k-gas signal to turn on Q14, and the output control signal cut-gas-KZ is low. By using the electromagnetic valve control circuit connected thereto (not in the circuit part of this control board, but inside the machine, which will be further explained in the subsequent application examples of the present invention, and will not be explained here in detail), the machine can be connected to the compressed air supply path, thereby providing ion gas for igniting the arc between the cutting gun and the workpiece.

[0025] 11) The gas shielded welding gun switch detection circuit is mainly composed of 5V and 15V power supplies, resistors R51, R52, R54, R55, R58, diode D19, capacitors C17 and C19, NPN transistor Q7, and CN4 socket. CN4 is the socket of the welding gun switch connection line, which is connected to the switch control line of the gas shielded welding gun through the plug and its control line. The collector of Q7, that is, the trig signal, is connected to the 36th pin of the microprocessor U1B. When selecting MIG, MAG or FLUX welding, if the welding gun switch is not closed, Q7 is turned on, and U1B can detect the low level of its 36th pin trig signal, which means that the welding gun switch is not closed; if the welding gun switch is closed, Q7 is cut off or not conducting, and U1B can detect the high level of the trig signal, which means that the welding gun switch is closed. When the welding gun switch is detected to be closed, the microprocessor will issue a corresponding control instruction. For example, in MIG and MAG welding, the Gdriv signal is output to make the electromagnetic valve work and perform advance gas supply control; the PWM signal is output, and the IGBT drive enable signal output is not turned off, so that the welding machine has output; the Mdriv signal is output to control wire feeding; if the arc is struck, there is welding current output to realize the output characteristics and welding control of gas shielded welding; on the contrary, if the welding gun switch is detected to be disconnected again, the control process is different, and there are control processes such as gas delayed gas sealing and energy-consuming braking processing when the wire stops feeding; when FLUX welding is selected, the control process is basically similar, except that there is no action control of the electromagnetic valve.

[0026] 12) Overheat protection signal detection circuit, mainly composed of 15V power supply, CN8 socket, resistors R53, R56, R57, capacitor C12; pin 4 and pin 5 (connected to 15V) of CN8 socket are connected to the overheat protection WKQ thermostat inside the welding machine, and WKQ is installed close to the aluminum heat sink surface of IGBT inside the machine; OT end is overheat protection signal, which is connected to pin 29 of the microprocessor; when WKQ is not in action, that is, when there is no overheating phenomenon, the OT signal is low level; on the contrary, when WKQ is in action, the OT signal is high level, and the sampling and output control of the OT signal by the microprocessor can make the OH indicator light on the front panel of the machine to indicate overheating. At the same time, the welding machine will have no current output, but the cooling fan will continue to work. After cooling for a period of time, WKQ will automatically recover, at this time, the OH indicator light will go out, and it can be operated again. The above is the overheat protection control process and working principle of the present invention.

[0027] 13) MCU microprocessor control circuit. See the attached Figure 1 See the attached for the specific circuit. Figure 1 This part of the circuit is attached Figure 1The rest of the above mentioned parts are mainly composed of MCU microprocessor U1B, program burning interface CN2, capacitors C3, C11, C26 and C32, method selection button SW1, resistors R72, R28, R62, R66, 5V and 15V power supplies. The microprocessor control circuit is mainly responsible for sampling some signals and outputting control signals, and it completes various control requirements under the control of the program written inside. The sampling of some signals and the output of control signals have been explained in the previous related content, and the relevant signal identification is also included in this part of the circuit, so I will not repeat it here.

[0028] Attached Figure 1 In the process, the control signals output by the 11th foot or PB and the 12th foot or PA of the microprocessor control circuit are two groups of PWM square wave pulse signals, and the frequency of the square wave is fixed, which is several tens of KHz. There is a fixed time difference between the two groups of square wave pulse signals, which is also called dead time in professional terms. It is one of the important parameters to ensure the alternating operation of the two groups of IGBT switches in the inverter main circuit. This time is determined by the parameter setting of the microprocessor control software. It should be noted here that the output PWM pulse width modulation signal is a signal that determines the output voltage and current of the machine inverter main circuit. Its pulse width depends on: 1) In the MMA welding control state, it is jointly determined by the welding current or thrust current given signal and the output current feedback signal, and is also affected by the output voltage. The object or target of control is the output current size. During welding, the welding current given signal is determined by the current given potentiometer; the thrust current given signal is set by the control software; the current negative feedback control signal is i f2Signal. By using different given and current negative feedback signals, the analog sampling signals of these signals are obtained through the software control of the microprocessor, and analog-to-digital conversion is performed. After that, the digital PI (proportional integral) control operation is used. The result of the operation determines the pulse width or duty cycle of the PWM pulse signal output by the microprocessor. Through the control of the IGBT drive circuit, the two groups of IGBTs in the inverter main circuit are in an alternating conduction state, which ultimately determines the output current and voltage of the welding machine, and realizes accurate control of the output current parameters. And the output characteristics are the decreasing characteristics of the constant current band drag. Further, when the welding current given signal remains unchanged, as the current detected by the welding machine circuit increases, and after reaching the given set value, the difference between the welding current given signal and the current negative feedback control signal will decrease with the increase of current. After PI control, the output PWM pulse width or duty cycle is reduced, and the output voltage of the welding machine is reduced. This process is also called current cutoff negative feedback control. After that, with a slight increase in current, the voltage will decrease a lot. When the output voltage drops below 16V, as the voltage decreases, the control circuit can increase the output PWM pulse width or duty cycle, so that the welding current increases according to the set thrust current parameters, and finally forms a constant current band-drag descent characteristic. When the welding current given signal changes, the current cutoff negative feedback setting value is different, but the other control processes are similar. Such control also meets the basic requirements of manual welding. 2) When TIG welding or CUT cutting control, the control process is similar to the above manual welding. It is just that the thrust current stage control below 16V is not performed, but the output characteristics of the machine are constant current descent characteristics. 3) When MIG, MAG welding or FLUX welding, the output characteristics of the welding machine are jointly determined by the welding voltage given signal and the output voltage negative feedback signal. The object or target of control is the output voltage. During welding, the welding voltage given signal is determined by the voltage adjustment potentiometer; the voltage negative feedback control signal is U 2f Signal. By using different voltage given and output voltage negative feedback signals, the analog sampling signals of these signals are obtained through the software control of the microprocessor, and analog-to-digital conversion is performed. After that, the digital PI (proportional integral) control operation is adopted. The result of the operation determines the pulse width or duty cycle of the PWM pulse signal. Through the control of the IGBT drive circuit, the two groups of IGBTs in the inverter main circuit are in an alternating conduction state, which ultimately determines the size of the output voltage and realizes the accurate control of the output voltage parameters. And the output characteristics are flat characteristics. Its characteristics are: the load current changes greatly, while the output voltage changes very little, and the output voltage during welding remains relatively stable. Only when the voltage given signal changes, the output voltage will change significantly. The current size during welding depends on the wire feeding speed. Increasing the wire feeding speed will increase the welding current; conversely, when the wire feeding speed is reduced, the welding current will also decrease.

[0029] The above part is the circuit composition of the control board of the present invention, the external connection description of each connecting plug, and the description of the relevant control principle.

[0030] The circuit design of the control board of the present invention has its own unique features. The content of the patent application of the present invention is to protect the circuit design of the welding and cutting machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Attached Figure 1 It is a circuit principle block diagram of the control board of the present invention;

[0032] Attached Figure 2 It is a schematic diagram of the electromagnetic valve control, wire feeder output connection, and wire feeder voltage feedback circuit of the control board of the present invention;

[0033] Attached Figure 3 It is the principle diagram of the voltage setting circuit and the current setting circuit of the control board of the present invention;

[0034] Attached Figure 4 It is the principle diagram of the overcurrent protection control and LED2 indication circuit of the control board of the present invention;

[0035] Attached Figure 5 It is the principle diagram of the rectification, resistance network and filtering circuit of the control board of the present invention;

[0036] Attached Figure 6 It is a schematic diagram of the IGBT low-voltage side drive circuit of the control board of the present invention;

[0037] Attached Figure 7 It is the current parameter display and LED indication circuit principle diagram of the control board of the present invention;

[0038] Attached Figure 8 It is a schematic diagram of the wire feeder driving circuit of the control board of the present invention;

[0039] Attached Fig. 9 It is a circuit schematic diagram of the cutting gun switch detection, cutting arc ignition high frequency control, cutting output conversion control, and cutting gas valve control of the control panel of the present invention;

[0040] Attached Fig.10 It is a schematic diagram of the gas shielded welding gun switch detection circuit of the control panel of the present invention;

[0041] Attached Fig.11 It is a schematic diagram of the overheat protection signal detection circuit of the control board of the present invention;

[0042] Attached Fig.12 It is a circuit principle block diagram of a part of an application example connected to the control board of the present invention;

[0043] Attached Fig.13It is the circuit schematic diagram of the power-on buffer circuit, rectification and filtering circuit, IGBT inverter circuit, primary current detection circuit, connection of the main transformer and part of its working winding, welding output rectification, filtering and voltage sampling circuit in the application example part;

[0044] Attached Fig.14 It is the circuit schematic diagram of the cutting conversion control of the application example part, as well as the cutting output rectification, filtering and high-frequency coupling part;

[0045] Attached Fig.15 This is the circuit schematic diagram of the IGBT high-voltage side drive part of the application example;

[0046] Attached Fig.16 This is the circuit schematic diagram of the high-frequency control part of the application example;

[0047] Attached Fig.17 This is the circuit schematic diagram of the cutting gun switch signal detection and the electromagnetic valve control part during cutting in the application example part. Implementation

[0048] The present invention relates to a control board of an inverter welding and cutting machine with five welding and one cutting method. The circuit composition block diagram of the control board is shown in the attached Figure 1 As shown, the circuit mainly includes 13 sub-parts: 5V power supply and Vdriv power supply circuit; output voltage sampling, signal conversion processing and filtering control circuit; electromagnetic gas valve control, wire feeder output connection, wire feeder voltage feedback circuit; voltage given signal circuit and current given signal circuit; overcurrent protection control and LED2 indication circuit; rectification, resistor network and filtering circuit; IGBT low-voltage side drive circuit; current parameter display and LED indication circuit; wire feeder drive circuit; cutting gun switch detection, cutting arc high-frequency control, cutting output conversion control, cutting gas valve control circuit; gas shielded welding gun switch detection circuit; overheat protection signal detection circuit; MCU microprocessor control circuit. Below, the above circuit is explained as follows:

[0049] 1) 5V power supply and Vdriv power supply circuit. See attached Figure 1Part ① of it. On the control board, a part of the power supply circuit is 5V. This circuit is composed of a 15V power supply, an integrated voltage regulator, a capacitor and an electrolytic capacitor. It can obtain a 5V power supply and supply other circuits as a working power supply. The 15V power supply comes from other circuits of the welding machine, such as the switching power supply circuit, etc. It is introduced into the control board through the 3rd pin of CN3; the other part of the circuit is the Vdriv power supply circuit. The CN1 plug is connected to a secondary winding of the main transformer through a connecting line. When there is an inverter process, there is a voltage input on CN1. After rectification and capacitor output filtering circuit, Vdriv DC power supply can be obtained to supply the electromagnetic valve control circuit of part ③ and the wire feeder drive circuit ⑨ to work. 2) Output voltage sampling, signal conversion processing and filtering control circuit. See attached Figure 1 ② in the figure. Connect the CN9 plug and its control line to the output end of the machine during welding. Note that it is not the output end during cutting. The signal conversion processing and filtering circuit part is relatively simple, which is a resistor voltage divider and capacitor filtering circuit. Get U at the output VFB+ and VFB- 2f Voltage feedback signal, which is connected to pins 23 and 24 of the microprocessor U1B. 2f The output voltage feedback analog signal is converted into digital form, and finally U 2f The digital quantity of the feedback signal is used for PI (proportional integral) negative feedback control operation of the output voltage during MIG, MAG and FLUX welding control.

[0050] 3) Solenoid valve control, wire feeder output connection, wire feeder voltage feedback circuit. See attached Figure 1 Part ③ of the circuit. See the attached Figure 2 , mainly composed of CN5 socket, Vdriv DC power supply, resistors R5~R10, R88, capacitor C5, diode D1, and N-channel MOS tube Q12. For the output connection part of the wire feeder, pin 1 of CN5 is connected to the M+ terminal, that is, the positive polarity terminal of the wire feeding motor. Pin 2 of CN5 is connected to the M- terminal, that is, the negative polarity terminal of the wire feeding motor. The wire feeding motor is a component of the wire feeding mechanism inside the machine; the signal at the M+ and M- terminals is the armature voltage of the wire feeding motor. When there is voltage at the M+ and M- terminals, the wire feeding motor runs and wire feeding control can be achieved. Otherwise, the wire feeding machine will not rotate and will not feed wire. For the wire feeding voltage feedback circuit, in the attached Figure 2In the circuit, it is mainly composed of resistors R5~R7 and capacitor C5. The wire feeding voltage feedback signal spd is taken from the voltage division signal at both ends of the wire feeding motor, which is transmitted to the 41st pin of the microprocessor U1B. For the electromagnetic valve control circuit part, the 3rd pin of CN5 is connected to the positive polarity end of the electromagnetic valve (for gas shielded welding), and its 4th pin is connected to the negative polarity end of the valve. The Gdriv control signal comes from the 44th pin output control terminal of the microprocessor U1B. When the Gdriv signal output makes the Q12 tube conductive, the electromagnetic valve can be activated. On the contrary, the electromagnetic valve is closed. This can realize the on and off control of the shielding gas. In addition, through the setting of the microprocessor software, the early gas supply and delayed gas closing time control during gas shielded welding can be realized, and these times can be set or modified by the control software.

[0051] 4) Voltage given signal circuit and current given signal circuit. See attached Figure 1 Part ④ of the circuit. For the voltage setting circuit, it mainly includes 5V power supply, variable potentiometer VR2, diode D25, resistors R76, R76, capacitors C23 and C24; adj2 signal is connected to pin 37 of microprocessor U1B, and adj2 signal is the output voltage setting signal for MIG, MAG or FLUX welding. For the current setting circuit, it mainly includes 5V, variable potentiometer VR1, diode D20, resistors R60, R61, capacitors C20 and C18; adj1 signal terminal is connected to pin 22 of U1B, and adj1 signal is the output current setting signal for MMA, TIG and CUT cutting, or the output current setting signal for MIG, MAG or FLUX welding.

[0052] For overcurrent protection, if overcurrent is detected during operation, it will be indicated by the LED2 indicator on the control circuit board, and the control circuit will also shut down the welding machine output. At this time, the user needs to reduce the current used, and turn off the power supply and then close the power switch again before using the welding machine again. If the LED2 light cannot be turned off, it means that the control circuit may be faulty. The working principle of the overcurrent protection control circuit is as follows:

[0053] 5) Overcurrent protection control and LED2 indication circuit. See attached Figure 1 Part ⑤ of the circuit. See the attached Figure 4 , mainly composed of 15V power supply, resistors R37~R43, capacitors C16 and C100, diodes D11 and D12, indicator LED2, NPN transistor Q5, PNP transistor Q4; i f1 The signal terminal comes from the attached Figure 5The rectifier, resistor network and filter circuit ⑥ on the left side of the middle part, the input end of the circuit is connected to the 6th and 7th pins of CN3, which are connected to the detection signal of the primary current of the main transformer. This current detection signal is obtained after rectification, resistor network transformation and capacitor filtering; when overcurrent occurs, Q5 and Q4 are turned on, LED2 lights up, indicating that overcurrent occurs, and at the same time, OCK1 and OCK2 overcurrent protection control signals can be obtained. The OCK2 signal is connected to the 13th pin of the microprocessor U1B, and the OCK1 signal is connected to a control end of the IGBT low-voltage side drive circuit ⑦. When the microprocessor receives an excessively large OCK2 signal, it can turn off the output of the PWMe pulse output enable control signal of the 19th pin of its U1B, and the OCK1 signal controls the IGBT low-voltage side drive circuit, so that the drive circuit stops outputting the PWM drive pulse signal, stops the inverter main circuit from working, and the machine also stops outputting. When the overcurrent phenomenon is relieved, the LED2 indicator light will go out before it can be operated again.

[0054] 6) Rectification, resistor network and filter circuit. See attached Figure 1 The specific circuit is shown in the attached Figure 5 In the main circuit, a current detection transformer is provided in the primary circuit of the welding transformer, which is used to detect the primary current of the main transformer. The detection signals CT1 and CT2 are connected to the control board through the 6th and 7th pins of the CN3 plug. After being rectified by the bridge rectifier circuit composed of diodes D3, D4, D13 and D14, and then filtered by the post-stage resistor network and capacitor, i can be obtained. f1 Signal and i f2 Signal. i f1 The signal is connected to the overcurrent protection control and LED2 indication circuit, see the attached Figure 1 Part ⑤ in the above is involved in the control of overcurrent protection. The control principle of this part can be found in the relevant overcurrent protection control part of this manual. No further description will be given here; i f2 The signal is connected to pins 20 and 21 of the microprocessor U1B. The microprocessor can f2 The current feedback analog signal is converted into digital form, and the digital value of the current feedback signal is finally obtained, which is used as the current negative feedback signal to participate in output control.

[0055] IGBT drive circuit, IGBT drive circuit is divided into high-voltage side drive circuit and low-voltage side drive circuit, the low-voltage side drive circuit part is on the control board, and the high-voltage side drive circuit part is on the circuit board inside the welding machine.

[0056] 7) IGBT low voltage side drive circuit. See attached Figure 1 Part ⑦ of the circuit. See the attached Figure 6 The primary of the transformer is driven by the IGBT (inside the welding machine, connected to the 1st and 2nd pins of CN3, attached Figure 6 The drive transformer and its primary are not drawn in the figure), Q1 and Q2 drive chips (NCE4614), MOS tube drive UB1 chip (FL560), NPN transistors Q3 and Q8, diodes D5~D10, resistors R1, R11~R15, R21~R27, capacitors C7~C8 and C25, 15V power supply, as well as PWMe and OCK1 control signals, and CN3 socket; the PA end is connected to the 12th pin of the microprocessor U1B; the PB end is connected to the 11th pin of U1B; the PWMe end is connected to the 19th pin of the microprocessor U1B; the OCK1 end is connected to the overcurrent protection control and LED2 indication circuit. The circuit of this part is shown in the attached figure. Figure 1 Part ⑤ in the figure; OCK1 terminal is the overcurrent protection control signal terminal. When the control circuit detects an overcurrent phenomenon, OCK1 terminal is a high-level signal, which can turn on the Q3 and Q8 transistors and pull the 2nd (HIN terminal) and 3rd (LIN terminal) of UB1 to a low level, thereby turning off the drive pulse signal output by UB1, so that the IGBT tube in the main circuit will not be turned on, thereby realizing overcurrent protection control; PWMe terminal is the IGBT drive signal enable control signal terminal. When this terminal is a high-level signal, the 2nd (HIN terminal) and 3rd (LIN terminal) of UB1 can be pulled to a low level, thereby turning off the drive pulse signal output by UB1, so that the IGBT tube in the inverter main circuit is not turned on. On the contrary, when the PWMe terminal is a low level, UB1 can have the conditions to output the drive pulse signal, so that the IGBT tube in the inverter main circuit can be turned on conditionally; PA and PB terminals are the PWM (pulse width modulation signal) output control terminals output by the microprocessor U1B. Pins 1 and 2 of the CN3 socket on the control board are connected to the attached Figure 3 The IGBT in the drive transformer is the primary side.

[0057] 8) Current parameter display and LED indication circuit. See attached Figure 1 The specific circuit is shown in the attached Figure 7, mainly including digital tube display table U3 (5631A), display driver control chip U2 (TM1652), and seven indicator lights: OH overheating D33, MMA welding D24, TIG welding D29, CUT cutting D32, MAG welding D21, MIG welding D28, and FLUX welding D27; U3's o1~o8 are connected to the corresponding connection points of U2, among which o1~o5 are also connected to the anodes of D27, D28 and D33, D29, D24 and D32, D21 respectively, and the cathodes GR5 of D32 and D33 are connected to the corresponding connection points of U2. The cathodes GR4 of D21, D24, D27, D28 and D29 are connected to the corresponding connection points of U2. GR1, GR2 and GR3 of U3 are connected to the corresponding connection points of U2 respectively. The 16-pin data of U2 is the control signal terminal. Which indicator light is on depends on the level of o1~o5 signals and the level control state of GR4 and GR5 signals, which depends on the data control signal sent by the microprocessor. At the same time, the current parameters displayed by the digital tube also depend on the data control signal. Under the control of the microprocessor control software, the corresponding indicator light can be lit according to the operation of the SW1 method selection button and the output current signal obtained to indicate the user's selection operation, which also determines the control of different welding or cutting methods and the display of current parameters.

[0058] The control panel of the present invention, viewed from the outside of the welding machine, has a current parameter display table, a welding and cutting method selection button, seven LED indicator lights, a voltage adjustment potentiometer, and a current adjustment potentiometer on the top of the operation control panel. The seven LED lights include OH overheating, MMA welding, MIG welding, MAG welding, FLUX welding, TIG welding, and CUT cutting indicator lights. Through the touch button, five welding methods, MMA welding, TIG welding, MIG welding, MAG welding, and FLUX welding, and one CUT cutting method can be selected. When selecting a method, the corresponding indicator light will light up, so it is more intuitive. When selecting MMA welding, TIG welding, and CUT, the adjustable parameters are welding or cutting current, which are adjusted by the corresponding current adjustment potentiometer; when selecting MIG welding, MAG welding, or FLUX welding, the adjustable parameters are wire feeding speed or current, voltage, and the method adopted is a collaborative or linkage adjustment method, rather than an independent or separate adjustment method for welding parameters.

[0059] Welding parameters are adjusted independently or separately. As the name implies, welding voltage and current are adjusted separately. This adjustment method has high requirements for welding operators. They need to have more welding operation knowledge and skills to obtain a good matching relationship between welding voltage and current. Otherwise, good weld quality cannot be obtained. This is quite difficult for ordinary operators. Therefore, the disadvantages of this adjustment method are also obvious.

[0060] Collaborative or linkage adjustment means that when the welding voltage parameter is adjusted, the welding current parameter automatically changes, or when the welding current parameter is adjusted, the welding voltage parameter automatically changes. The result of this change or automatic adjustment is set by the welding machine developers based on the accumulated knowledge and skills of welding operations. Therefore, it does not require the welding operator to have high relevant knowledge and skills. In other words, the collaborative or linkage adjustment function can greatly facilitate the welding machine operator to adjust the welding parameters, simplify the welding operation, and make it more convenient to use. It is more practical, especially for beginners in welding operations.

[0061] The functions of the display and operation control circuit are: 1) to realize the selection and control of five welding methods, namely MMA, TIG, MIG, MAG and FLUX welding, and one CUT cutting method; 2) to realize the adjustment and control of the respective welding parameters under different methods; 3) to realize the display of various states, including the indication of different methods; overheating indication; current display.

[0062] 9) Wire feeder drive circuit. See attached Figure 1 Part 9 of the circuit. See the attached Figure 8 , mainly composed of MOS tube driver UB2 chip, N-channel MOS tubes Q11 and Q13, diode D2, capacitors C10 and C15, Vdriv and 15V power supply, resistors R29, R30, R32, R35, R36, R48, and Mdriv and Mbrake control signals of microprocessor U1B. The wire feeding motor is connected between M+ and M-. The Mdriv signal comes from pin 45 of the microprocessor; the Mbrake end is the wire feeding stop control signal end, which comes from pin 43 of the microprocessor. R36 and R48 are resistors with large wattage, which are used for motor braking; the Mdriv signal controls the Q11 tube after passing through the post-stage control circuit; the speed of the wire feeding motor is controlled by controlling the on and off time of the Q11 tube; the Mdriv signal is determined by the wire feeding speed set value signal and the spd wire feeding voltage feedback signal, and the digital PI (proportional integral) operation control method is used in the microprocessor to control the wire feeding speed. For example, the wire feeding speed can be changed by changing the given value of the wire feeding speed, which represents the wire feeding speed or current control during MIG, MAG or FLUX welding; when the Mdriv signal is changed, Q11 can be in an on-off state. Different Mdriv control signals will result in different motor armature voltages, so the motor speeds will be different. In addition, when the spd wire feeding voltage feedback signal changes, or when certain factors change and affect the change of the feedback signal, it will not have a significant impact on the wire feeding speed, and can achieve the purpose of stabilizing the wire feeding speed regulation and control. This is the working principle of the present invention for achieving wire feeding speed regulation and negative feedback control.

[0063] For the wire feeding stop brake or energy consumption brake control circuit, it is to control whether the parallel brake resistors R36 and R48 are connected to the wire feeding motor circuit. When the Mbrake signal terminal outputs the stop feeding control instruction, the output of the UB2 chip can turn on Q13 and turn off Q11, so that R36 and R48 are connected to the motor circuit and the wire feeding is stopped. R36 and R48 are connected to the motor circuit to quickly consume the energy of the wire feeding motor and perform energy consumption braking to prevent the welding wire from rushing out of the conductive nozzle of the welding gun too long and entering the molten pool when the welding is stopped, and the so-called wire sticking phenomenon occurs. In addition, if the welding wire extends too long from the conductive nozzle, it will also affect the arc initiation control of the next welding, which needs to be avoided.

[0064] 10) Circuits for cutting gun switch detection, cutting arc ignition high frequency control, cutting output conversion control, and cutting gas valve control. See attached Figure 1 The specific circuit is shown in the attached Fig. 9 , mainly composed of 5V and 15V power supplies, resistors R50, R63, R77~R86, capacitor C30 and electrolytic capacitor C31, NPN transistors Q9, Q10, Q14, Q15, and CN6 socket. Pin 2 of CN6 is connected to 15V, and its pin 3 is grounded. Pin 1 and pin 2 of CN6 are connected to the switch control signal cut-trig-KZ of the cutting gun through the plug and its control line.

[0065] The cut-trig signal in the circuit is the state detection signal of the cutting gun switch, which is connected to the 42nd pin of the MCU microprocessor controller U1B. During the cutting operation, when the cutting gun switch is not closed, the cut-trig-KZ signal is low, Q15 is cut off or not conducting, and the cut-trig signal is high; when the cutting gun switch is closed, the cut-trig-KZ signal is high, Q15 is conducting, and the cut-trig signal is low. The microprocessor can know whether the cutting gun switch is closed by detecting the high and low levels of the cut-trig signal and perform corresponding control. For example, high-frequency control during cutting; relay output conversion control; electromagnetic valve control of compressed air output, etc., see the further description below.

[0066] The 4th pin of CN6 is the high-frequency control signal cut-HF-KZ output during cutting; whether the cut-HF-KZ signal is low level or high level depends on the k-HF control signal, which is connected to the 40th pin of U1B. When it is detected that the switch of the cutting gun is closed, the microprocessor can output a high-level k-HF signal to turn on Q10, and the output cut-HF-KZ signal is a low-level signal. By using the high-frequency control circuit connected thereto (not in the circuit part of this control board, but inside the machine, which will be further explained in the subsequent application examples of the present invention, and will not be further explained here.), the machine can generate an arc-starting high-frequency high-voltage signal, thereby igniting the arc between the cutting gun and the workpiece.

[0067] The 5th pin of CN6 is the control signal cut-jdq-KZ for relay output conversion during cutting; whether the cut-jdq-KZ signal is low or high depends on the k-jdq signal, which is connected to the 39th pin of U1B. When the switch of the cutting gun is detected to be closed, the microprocessor can output a high-level k-jdq signal to turn on Q9, and cut-jdq-KZ is a low-level signal. By using the cutting output conversion relay control circuit connected thereto, the machine can realize the output conversion of the inverter main circuit part (Note: For the multifunctional machine of the present invention, the output requirements of the inverter main circuit are different during welding and cutting. For example, the output current is large and the output voltage is low (less than tens of volts) during welding; while during cutting, on the contrary, the output current is small and the output voltage is high (more than 90 volts, or even higher). Therefore, it is necessary to use a relay to control the output conversion. , so as to provide output guarantee for igniting the high-voltage and low-current arc between the cutting gun and the workpiece.

[0068] The 6th pin of CN6 is the electromagnetic valve control signal cut-gas-KZ output by the compressed air during cutting; whether the cut-gas-KZ signal is low or high depends on the k-gas signal, which is connected to the 38th pin of U1B. When it is detected that the switch of the cutting gun is closed, the microprocessor can output a high-level k-gas control signal to turn on Q14, and the output cut-gas-KZ signal is low. By using other electromagnetic valve control circuits connected to it (not in the circuit part of this control board, but inside the machine, which will be further explained in the subsequent application examples of the present invention, and will not be explained here in detail), the machine can be connected to the compressed air supply path, thereby providing ion gas for igniting the arc between the cutting gun and the workpiece.

[0069] 11) Gas shielded welding gun switch detection circuit. See attached Figure 1 The specific circuit is shown in the attached Fig.10, mainly composed of 5V and 15V power supplies, resistors R51, R52, R54, R55, R58, diode D19, capacitors C17 and C19, NPN transistor Q7, and CN4 socket. CN4 is the socket for the welding gun switch connection line, which is connected to the gas shielded welding gun switch control line through the plug and its control line. The collector of Q7, that is, the trig signal end, is connected to the 36th pin of the microprocessor U1B. When selecting MIG, MAG or FLUX welding, if the welding gun switch is not closed, Q7 is turned on, and the microprocessor can detect the low level of its 36th pin trig signal, which means that the welding gun switch is not closed; if the welding gun switch is closed, Q7 is cut off or not conducting, and the microprocessor can detect the high level state of the trig signal, which means that the welding gun switch is closed. When the welding gun switch is detected to be closed, the microprocessor will issue a corresponding control instruction. For example, in MIG and MAG welding, the Gdriv signal is output to make the electromagnetic valve work and perform advance gas supply control; the PWM signal output of UB1 is not closed so that the welding machine has output voltage; the Mdriv signal is output to control wire feeding; if the arc is struck, there is welding current output to realize the output characteristics and welding control of gas shielded welding; on the contrary, if the welding gun switch is detected to be disconnected again, the control process is different, and there are control processes such as gas delayed gas sealing and energy-consuming braking processing when the wire stops feeding; when FLUX welding is selected, the control process is basically similar, except that there is no action control of the electromagnetic valve.

[0070] 12) Overheat protection signal detection circuit. See attached Figure 1 ⑫ in the figure. For the specific circuit, see the attached Fig.11 , mainly composed of 15V power supply, CN8 socket, resistors R53, R56, R57, capacitor C12; pin 4 and pin 5 (connected to 15V) of CN8 socket are connected to the overheat protection WKQ thermostat inside the machine, and WKQ is installed close to the aluminum radiator surface of IGBT; OT end is the overheat protection signal end, which is connected to pin 29 of the MCU microprocessor; when WKQ is not in action, that is, when there is no overheating phenomenon, the OT signal is low level; on the contrary, when WKQ is in action, the OT signal is high level, and the OT signal sampling and output control of the microprocessor can make the OH indicator light on the front panel to indicate overheating. At the same time, it will stop output and cannot perform welding or cutting. But the cooling fan will continue to work. After cooling for a period of time, WKQ will automatically recover. At this time, the OH indicator light will automatically go out before welding or cutting operations can be performed again. The above is the overheat protection control process and working principle of the present invention.

[0071] 13) MCU microprocessor control circuit. See attached Figure 1 See the attached for the specific circuit. Figure 1 This part of the circuit is attached Figure 1The rest of the above mentioned parts are mainly composed of MCU microprocessor U1B, program burning interface CN2, capacitors C3, C11, C26 and C32, method selection button SW1, resistors R72, R28, R62, R66, 5V and 15V power supplies. The microprocessor control circuit is mainly responsible for sampling some signals and outputting control signals, and it completes various control requirements under the control of the program written inside. The sampling of some signals and the output of control signals have been explained in the previous related content, and the relevant signal identification is also included in this part of the circuit, so I will not repeat it here.

[0072] Attached Figure 1 In the process, the control signals output by the 11th or PB and 12th or PA terminals of the microprocessor are two groups of PWM square wave pulse signals, and the frequency of the square wave is fixed, which is several tens of KHz. There is a fixed time difference between the two groups of square wave pulse signals, which is also called dead time in professional terms. It is one of the important parameters to ensure the alternating operation of the two groups of IGBT switches in the inverter main circuit. This time is determined by the control software parameter setting of the microprocessor. It should be noted here that the output PWM pulse width modulation signal is a signal that determines the output voltage and current of the machine inverter main circuit. Its pulse width depends on: 1) During MMA welding, it is determined by the welding current or thrust current given signal and the output current feedback signal, and is also affected by the output voltage. The object or target of control is the output current. During welding, the welding current given signal is determined by the current given potentiometer; the thrust current given signal is set by the control software; the current negative feedback control signal is the i mentioned earlier. f2Current feedback signal. Using different given and current negative feedback signals, through the software control of the microprocessor, the analog sampling signals of these signals are obtained, and analog-to-digital conversion is performed. After that, the digital PI (proportional integral) control operation is used. The result of the operation determines the pulse width or duty cycle of the PWM pulse signal output by the microprocessor part. Through the control of the IGBT drive circuit, the two groups of IGBTs in the inverter main circuit are in an alternating conduction state, which ultimately determines the size of the output current and voltage of the welding machine, and realizes the accurate control of the output current parameters. And make the output characteristics of the welding machine a constant current band drag drop characteristic. Further, when the welding current given signal remains unchanged, as the current detected by the welding machine circuit increases, and after reaching the given set value, the difference between the welding current given signal and the current negative feedback control signal will decrease with the increase of current. After PI control, the pulse width or duty cycle of the welding machine output PWM chip is reduced, and the output voltage of the welding machine is reduced. This process is the so-called current cutoff negative feedback control. That is, feedback control that only works when the current reaches the set value of the welding current potentiometer. Thereafter, with a slight increase in current, the voltage will drop a lot. When the output voltage drops below 16V, as the voltage decreases, the control circuit can increase the pulse width or duty cycle of the output PWM chip, so that the welding current increases according to the set thrust current parameters, and finally forms a constant current with external drag descending characteristics. When the welding current given signal changes, the current cutoff negative feedback setting value is different, but the other control processes are similar. In this way, between the minimum and maximum values ​​set by the current potentiometer, countless descending characteristic curves can be obtained. Such control also meets the basic requirements of manual arc welding. 2) When TIG welding or CUT cutting, the control process is very similar to the above manual welding. It is just that the external drag or thrust current stage control below 16V is not performed, but the output characteristics of the machine are constant current descending characteristics. 3) When MIG, MAG or FLUX welding, the output characteristics of the welding machine are determined by the welding voltage given signal and the output voltage negative feedback signal. The object or target of control is the output voltage of the welding machine. When welding, the welding voltage given signal is determined by the voltage adjustment potentiometer; the voltage negative feedback control signal is the VFB+, VFB- signal or U mentioned above. 2fSignal. By using different voltage given and output voltage negative feedback signals, the analog sampling signals of these signals are obtained through the software control of the microprocessor, and analog-to-digital conversion is performed. After that, the digital PI (proportional integral) control operation is used. The result of the operation determines the pulse width or duty cycle of the output PWM pulse signal. Through the control of the IGBT drive circuit, the two groups of IGBTs in the inverter main circuit are in an alternating conduction state, which ultimately determines the size of the output voltage and realizes accurate control of the output voltage parameters. And the output characteristics of the welding machine are flat characteristics, rather than the decreasing characteristics of the constant current band. Its characteristics are: the load current changes greatly, while the output voltage changes very little, and the output voltage during welding remains relatively stable. Only when the voltage given signal changes, the output voltage will change significantly. The current size during welding depends on the wire feeding speed. Increasing the wire feeding speed will increase the welding current; conversely, when the wire feeding speed is reduced, the welding current will also decrease.

[0073] The above part is the circuit composition of the control board of the present invention, the external connection description of each connecting plug, and the description of the relevant control principle.

[0074] As we all know, the control panel is installed on the front panel of the welding and cutting equipment, and it is also the user's operating control panel. However, as a complete welding and cutting equipment, the control panel alone cannot constitute a whole device. Other parts are also needed to form a complete device, such as the chassis of the equipment, including the front panel, rear panel, bottom plate, shell, handle, etc.; some parts inside the equipment, such as the solenoid valve and its air pipe pipeline that control the gas supply of gas shielded welding; the solenoid valve and its air pipe pipeline that control the compressed air supply; the power switch that controls the power on and off, the power supply cable and its fixed wire pull-off or wire fixer; the cooling fan; the inverter main circuit, including the input rectifier, filter electrolytic capacitor, IGBT tube assembly (including IGBT, aluminum radiator and its bracket, and overheat protection temperature relay or thermostat installed close to the surface of the aluminum radiator, etc.), the high-voltage side drive circuit of the IGBT and its drive transformer, the inverter main transformer and its primary current detection sensor, welding use Output rectifier fast recovery diode components (including fast recovery diodes, aluminum radiator and its bracket, etc.), output filtering and sampling circuits; for machines with cutting function, due to the large difference in current and voltage during welding and cutting, it is not possible to share a set of output rectifier fast recovery diode components with welding, and they need to be independent and separate. Therefore, output rectifier fast recovery diode components (including fast recovery diodes, aluminum radiator and its bracket, etc.), output filtering and sampling circuits for cutting are also required; there must be a switching power supply or DC power supply system to provide working power for the circuit board; the output connection part of the equipment, such as the gas shielded welding gun and its connection interface; the connection terminals of the workpiece; for multi-functional equipment, there are also output polarity conversion wiring devices, positive and negative output connection terminals for manual welding, argon arc welding, and plasma cutting, and switch line connection sockets for gas shielded welding guns and cutting guns.

[0075] In order to further illustrate the practical application results of the present invention, an application example is given below for illustration:

[0076] Attached Fig.12 This is a circuit diagram of an application example connected to the control board of the present invention. The power supply is 220-240V, 50 or 60Hz. For output current: MIG / MAG / FLUX welding, MMA welding and TIG welding, the rated current is 160A; CUT cutting, the rated current is 40A.

[0077] Looking from the front of the machine to the back, the control panel of the present invention is installed above the front panel of the inverter welding machine; the left side below the front panel is the connection area for the welding function, which is installed with: the European-style gas shielded welding gun interface (the interface part is provided with a control line connection socket for the welding gun switch) and its fixing seat, the European-style interface is used to connect the welding gun for MIG, MAG, and FLUX welding; the black negative polarity output quick connector, the red positive polarity output quick connector, the welding gun polarity conversion plug and its cable, the polarity conversion plug is used to connect the black or red output quick connector. For example, when MIG and MAG welding, the polarity conversion plug is connected to the red output quick connector, and the workpiece is connected to the black negative polarity output quick connector. This is the most commonly used output polarity connection method, called DC reverse connection (i.e. the workpiece is connected to the negative polarity output), and the arc stability is good and the spatter is small during welding. On the contrary, it is called DC positive connection (that is, the workpiece is connected to the positive polarity output). The arc stability is poor and the spatter is large during welding, so it is not used. Some FLUX flux-cored welding wires without gas protection or self-protection require DC positive connection during welding, while some FLUX welding wires require DC reverse connection, which can be connected according to the specific welding wire instructions. DC reverse connection is usually used in MMA welding, which is also for arc stability and small spatter. In TIG welding, since it is DC, DC positive connection is required, and the TIG welding gun is connected to the negative pole to avoid tungsten electrode burning affecting welding. The right side below the front panel is the connection area for the cutting function, which is equipped with a black gas-electric interface for connecting the cutting gun with negative polarity output, a red positive polarity output quick connector and a switch control line socket for the cutting gun. The workpiece is connected to the red positive polarity interface, and the plug of the gun switch is connected to its control line socket.

[0078] Looking forward from the back of the machine, on the left side of the rear panel of the inverter welding and cutting machine, there are: power switch, which is used to control the connection or disconnection of the power supply; 220V, 50 / 60Hz power supply line, connected to the power grid; shielding gas inlet interface for MIG and MAG welding, users can connect the corresponding shielding gas supply system according to the needs of the welding process, for example, through the air pipe to connect to the gas flow meter on the gas cylinder (CO2, 80%Ar+20%CO2, Ar and other gases); compressed air inlet interface for CUT cutting, users can connect to the air compressor or compressed air supply system that meets the gas flow and pressure requirements through the air pipe. The cooling fan of the welding and cutting machine is installed below. It is installed inside the machine. The cooling air enters the interior through the air inlet hole at the rear of the casing to cool the main internal components, such as the main transformer, IGBT and its heat dissipation components, fast recovery diode and its heat dissipation components, etc. On the right side of the rear panel, inside the machine, there are wire feeding mechanism, wire reel bracket, gas shielded welding gun European interface and wire feeding mechanism connection parts, etc.

[0079] Fig.12In the circuit, L and N are the power input terminals. The power supply connected is 220V, 50 / 60Hz. The grid power supply is connected to this input terminal through the power switch on the rear panel of the welding machine. The PE terminal is the protective grounding terminal, which is connected to the ground of the power supply system and the metal casing of the welding machine. Fig.12Part Ⓐ in the figure, the letters in the circle represent some circuits inside the example welding machine, the same below, no repetition) is connected between the input power supply and the rectification and filtering circuit (see part Ⓑ), the latter is also connected to the switching power supply circuit and the IGBT inverter circuit (see part Ⓒ); the switching power supply circuit is used to generate 15V and 24V2 DC working power supplies, where the 24V2 power supply is also connected to the cooling fan FAN installed on the rear panel of the welding machine through the CON2 socket. Of course, the 15V and 24V2 power supplies are also used for other circuits; the IGBT inverter circuit is connected to the IGBT high-voltage side drive circuit (see part Ⓙ), which is connected to the secondary of the drive transformer (see part Ⓚ), and the primary of the drive transformer is connected to pins 1 and 2 of the CN3 socket, and finally connected to pins 1 and 2 of the CN3 socket on the control board of the present invention; the aluminum radiator part of the IGBT inverter circuit, close to the IGBT tube, is also equipped with an overheating protection controller or thermostat WKQ, which is attached to the radiator, and the heat of the radiator will transfer To the thermostat WKQ, the control line of the thermostat is connected to the 1st and 2nd pins of CN8, and is connected to the 1st and 2nd pins of the CN8 socket on the control board of the present invention through its plug and control line; the output of the IGBT inverter circuit is connected to the primary current detection circuit (see part Ⓓ) and the main transformer. The primary current detection circuit is a current detection mutual inductor, and its detection part is connected in series to the primary circuit of the main transformer, and the output CT1 and CT2 ends of the detection circuit are connected to the 6th and 7th pins of the CN3 socket, and finally to the 6th and 7th pins of the CN3 socket on the control board of the present invention. 7-pin connection; the main transformer has five working windings, one is the primary winding, which is connected to the loop of the inverter circuit; one is the secondary winding of the wire feeder power supply, which is connected to the 1st and 2nd pins of the CN1 socket on the control board of the present invention through the connected CN1 socket, plug and its control line; one is the secondary high-frequency control circuit (see part Ⓗ) power supply winding, the control signal cut-HF-KZ of this circuit is connected to the 4th pin of the CN6 socket, and is connected to the 4th pin of the CN6 socket on the control board of the present invention through its plug and its control line; the connection of this circuit To the high-frequency coupling connection socket in the cutting output rectification, filtering and high-frequency coupling circuit (see part Ⓕ), the input (N5-1 and N5-2) of the circuit of part Ⓕ is connected to a secondary winding of the main transformer, which is called the cutting output working winding, and has the characteristics of higher voltage and larger current output; whether the circuit of part Ⓕ participates in the work also depends on the cutting conversion control circuit (see part Ⓖ), the control signal cut-jdq-KZ of this circuit is connected to the 5th pin of the CN6 socket, and is connected to the 5th pin of the CN6 socket on the control board of the present invention through its plug and its control line;ⒻThe positive polarity output Cut-OUT(+) of the circuit is connected to the red positive polarity quick connector in the cutting connection area on the upper and lower right sides of the front panel of the welding machine. The negative polarity output Cut-OUT(-) of the circuit is connected to the gas-electric output connection interface of the cutting gun in this area. The air nozzle of the gas-electric interface is connected to the output end of the electromagnetic air valve that controls the compressed air inside the machine through an air pipe. The input end of the air valve is connected to the compressed air intake interface on the rear panel of the welding machine through an air pipe. The main transformer also has a secondary winding, called the welding output working winding, which has the characteristics of low voltage and large current output. The winding has a center tap, and the tap is connected to the negative polarity of the welding output (Welding-OUT(-)), which is also the black quick connector or interface in the welding connection area below the front panel of the welding machine. The other two ends of the winding are connected to the welding output rectification, filtering and voltage sampling circuit (see part Ⓔ). The positive polarity output end of the circuit of part Ⓔ is connected to the positive polarity of the welding output (Welding-OUT(+)) in the welding connection area. The output voltage sampling signal U of the circuit is 2f Connected to the CN9 socket, and connected to the corresponding end of the CN9 socket on the control board of the present invention through its plug and its control line; Pins 1 and 3 of the CON5 socket are connected to the gun switch socket in the cutting connection area of ​​the front panel of the welding and cutting machine, and are connected to the switch control line of the cutting gun, and are also connected to the cutting gun switch signal detection circuit (see part Ⓜ), the output signal of which is cut-trig-KZ, which is connected to pin 1 of the CN6 socket, and is connected to pin 1 of the CN6 socket on the control board of the present invention through its plug and its control line; Pins 1 and 3 of the CON4 socket are connected to the cutting solenoid valve Cut-DCF that controls the on and off of compressed air inside the welding and cutting machine, and are also connected to the solenoid valve control circuit during cutting (see part Ⓝ), the input control signal of which is cut-gas-KZ, which is connected to pin 6 of the CN6 socket, and is connected to pin 6 of the CN6 socket on the control board of the present invention through its plug and its control line.

[0080] After understanding the above description, let's look at the specific circuit in the application example, so as to have a comprehensive understanding of the inverter welding and cutting machine used in the present invention.

[0081] Attached Fig.13 This is the circuit schematic diagram of the power-on buffer circuit (part Ⓐ), rectification and filtering circuit (part Ⓑ), IGBT inverter circuit (part Ⓒ), primary current detection circuit (part Ⓓ), connection of the main transformer and part of its working winding, and welding output rectification, filtering and voltage sampling circuit (part Ⓔ) in the application example part.

[0082] Attached Fig.13In the circuit, the power-on buffer circuit includes thermistor R55, contact K1B of relay K1A, N-channel Q4MOS tube, diodes D23 and D24, resistors R61 and R62, electrolytic capacitor C54, and 24V2 power supply. This part of the circuit is realized by the following control method: Fig.13 In the circuit, the formation of 24V2 voltage will lag behind the moment when the power supply switch is closed. The voltage on capacitor C54 gradually increases after the 24V2 voltage is added, that is, K1A will not act until the delay. K1B is connected in parallel with R55 and in series between the power supply of the welding machine and the input end of the rectifier bridge ZLQ; the action time of K1A lags behind the moment when the power switch is closed, and it is a delayed action. When the charging voltage on C47~C48 is stable, K1A will act, and its K1B will close and short-circuit R55, so that when the welding machine is normally inverted, a large current will flow through K1B. It is mainly to prevent the power switch from being turned on at the moment, because there is no voltage on C47~C48, which is equivalent to a short circuit, which will form a large surge current and burn the power switch. The function of the power-on buffer circuit is to limit the surge current by connecting R55 in series at the moment when the power switch is closed. In addition, the resistance value of R55 increases with its temperature rise. Therefore, it can play a better protective role.

[0083] Attached Fig.13 In the process, the power supply is rectified by the rectifier ZLQ and becomes pulsating direct current, which charges C47~C48. The voltage gradually increases and finally becomes a relatively stable +VCC or VCC high-voltage direct current.

[0084] Attached Fig.13 In the circuit, four IGBT tubes IGBT1, IGBT2 (a group of switches) and IGBT3, IGBT4 (another group of switches) and their surrounding resistors and capacitors form a half-bridge inverter circuit. The main transformer B1 has 6 windings, N1~N6, N6 is attached Fig.16 In the circuit, N1 is the primary and the others are the secondary. The primary current detection circuit (Ⓓ part) of the main transformer is actually the current detection transformer CT, through which the current detection signal output by CT1 and CT2 can be obtained and connected to the aforementioned CN3 socket. The N2 and N3 windings of B1A are centrally tapped, and the tapped ends are connected to the filter reactor L3 and then to the negative polarity quick connector in the welding connection area on the front panel of the machine. The four dual fast recovery diode modules D19~D22 form the output rectifier circuit of the machine during welding. Some resistors and capacitors in the rectifier output circuit form an anti-interference and filtering circuit. The U obtained from the output end 2f The voltage detection signal is connected to the CN9 socket and connected to the corresponding terminal of the CN9 socket of the control board of the present invention, U 2fThe output voltage sampling signal will participate in the output control of some welding methods of the welding machine, for example, the output voltage negative feedback control during MIG / MAG / FLUX welding; thrust current control during MMA welding. The overheat protection temperature controller or thermostat WKQ control line is connected to the CN8 socket and to the corresponding terminal of the CN8 socket of the control board of the present invention. The N4 winding of B1B of the main transformer provides the working power of the wire feeder, and its output line is connected to the CN1 socket and to the corresponding terminal of the CN1 socket of the control board of the present invention. The N5 winding of B1C of the main transformer, its output lines N5-1 and N5-2, are connected to the attached Fig.14 In the figure, N5 winding is the output winding during cutting operation. N6 winding of B1B of the main transformer provides working power for the high-frequency arc ignition circuit, see attached Fig.16 It can be seen from the description that the above circuit part is a typical and common inverter welding machine application circuit. Therefore, there are a lot of descriptions of other working principles of the circuit, which will not be repeated here.

[0085] Attached Fig.14 This is the circuit diagram of the cutting conversion control (Part Ⓖ) of the application example part, and the cutting output rectification, filtering and high-frequency coupling part (Part Ⓕ). Fig.14 The CN7 socket is connected to the attached Fig.16 The high-frequency control circuit of L4 can make the cutting circuit obtain high-frequency and high-voltage arc-starting signals under the action of the high-frequency control circuit, etc. Fig.16 The working principle of the Fig.14 It can be seen that whether the output rectification and filtering circuit has output during cutting is determined by relay K2A and its control circuit. The contact K2B of K2A is connected in series in the input circuit of the output rectifier, and its input ends are N5-1 and N5-2, which are obtained from the N5 secondary winding of the main transformer B1. The output rectification circuit during cutting uses D12, D13, D15 and D16 fast recovery diode modules to form a bridge rectifier circuit. This circuit includes a filter circuit composed of peripheral resistors and capacitors, which is relatively common. Therefore, their functions will not be described here. For cutting conversion control, it is composed of N-channel MOS tube Q2, U6 optocoupler, D10 diode, resistors R29, R32, capacitor C25, and 15V and 24V2 power supplies. The input control signal of the circuit is cut-jdq-KZ, which is connected to the attached Fig.17Pin 5 of the CN6 socket is connected to pin 5 of the CN6 socket on the control board of the present invention through its plug and its control line. Whether the cut-jdq-KZ signal is low level or high level depends on the k-jdq signal of the control board circuit of the present invention, which is connected to pin 39 of the microprocessor U1B. When it is detected that the cutting gun switch is closed, the microprocessor can output a high level k-jdq signal, so that the output cut-jdq-KZ signal is low level. By using the cutting conversion control, the machine can realize the output conversion of the inverter main circuit part, thereby providing output guarantee for igniting the high voltage and low current (for example, current 20~40A, voltage 88~96V) arc between the cutting gun and the workpiece.

[0086] Due to the attached Fig.13 The inverter main circuit adopts a half-bridge inverter circuit. The four IGBT tubes IGBT1, IGBT2, and IGBT3, IGBT4 are divided into two groups of electronic switches. Therefore, two groups of IGBT drive circuits are required. The circuit forms of the two drive parts are basically the same. Since the PWM signal driving power output by the microprocessor chip of the control board part of the present invention is small, it needs to pass through the low-voltage side drive control circuit, and then through the QDBYQ drive isolation transformer for isolation and power amplification. Finally, the high-voltage side drive circuit controls the on or off working state of the two groups of IGBT tubes. The specific IGBT high-voltage side drive circuit is described below:

[0087] Attached Fig.15 It is the circuit schematic diagram of the IGBT high-voltage side driving part (Ⓙ part) of the application example part. This circuit is usually designed on the power board, close to the IGBT tube. The circuit consists of a QDBYQ driving transformer, diodes D17 and D18, and some resistors and capacitors; N1 of QDBYQ is the primary or low-voltage side winding, which is connected to pins 1 and 2 of CN3, and is connected to the corresponding wiring terminals of the CN3 socket of the control board of the present invention through its connecting wires, and is connected to the IGBT low-voltage side driving circuit; N2 and N3 of QDBYQ are two independent secondary or high-voltage side windings, which are connected to the high-voltage side driving circuit of this part. The output ends of the high-voltage side driving circuit, such as G1, G2, E1, G3, G4, E2, are respectively connected to the attached Fig.13 In the figure, it corresponds to the control terminal of IGBT. When there is a driving pulse signal on the primary side of the driving transformer, a driving signal will be generated in the secondary windings N2 and N3. Then, through the above two sets of driving circuits, one of the two sets of electronic switches, IGBT1 and IGBT2 and IGBT3 and IGBT4, can be driven to be in the on state. After a certain period of time, the on set of IGBT switches is turned off, and after a certain dead time, the other set of IGBT switches is turned on again. In this way, the on and off control is alternated. In (Appendix Fig.13With the cooperation of the commutation capacitors (C39 and C40, and C50 and C51), a medium-frequency AC can be formed in the primary winding N1 of the main transformer B1; when there is no driving signal in the primary winding of the driving transformer, the two groups of IGBT electronic switches IGBT1 and IGBT2 and IGBT3 and IGBT4 are in the off state.

[0088] Attached Fig.16 This is the circuit schematic diagram of the high-frequency control part (Ⓗ part) of the application example part. The welding machine involved in the present invention, when using the cutting method, will use a high-frequency control circuit to realize the ignition of the plasma arc. The circuit consists of the N6 secondary winding of the main transformer B1, the high-voltage package GYB (for high-voltage boosting), the spark arrester FD, the relay K3A, the N-channel MOS tube Q1, the CN7 socket, the U5 optocoupler, the D8 diode, the resistors R20, R26, R49 and R50, the capacitors C18, C41~C43, and the 15V and 24V2 power supplies. Connect to the attached via the plug of the CN7 socket and its connecting wire. Fig.14 The high-frequency coupling inductor L4 in the circuit has a relatively small number of primary winding turns and is connected in series in the high-frequency high-voltage signal output loop of the high-frequency control circuit, while the secondary winding turns of L4 are relatively large. Therefore, L4 not only plays the role of coupling the high-frequency high-voltage signal, but also has the function of boosting the high-frequency high-voltage signal generated by the previous stage. This makes the attached Fig.14 The high-frequency and high-voltage signal intensity in the cutting output circuit is very high, which makes it easy to realize the arc ignition control of the cutting gun. The contact K3B of relay K3A is connected in series in the circuit of the secondary winding of N6, and the primary winding of R49, C43 and GYB are also in this circuit. If the N6 winding has an output voltage, at the same time, when K3B is closed, the secondary output voltage of GYB can be rapidly increased. When the increased voltage reaches the breakdown voltage between the two electrode gaps of FD, a discharge phenomenon will be formed between the two electrodes, so that a high-frequency and high-voltage signal can be obtained in the circuit composed of the primary winding of L4 connected to C41, C42 and CN7. The working state of relay K3A is controlled by its control circuit. The input of this circuit is the cut-HF-KZ control signal, which is connected to the attached Fig.17 Pin 4 of the CN6 socket is connected to pin 4 of the CN6 socket on the control board of the present invention through its plug and its control line. Whether the signal cut-HF-KZ is low level or high level depends on the k-HF signal of the control board circuit of the present invention, which is connected to pin 40 of the microprocessor U1B. When it is detected that the switch of the cutting gun is closed, the microprocessor can output a high level k-HF signal, so that the output cut-HF-KZ signal is low level. By using the high-frequency control circuit connected thereto, Q1 can be turned on, and the machine generates an arc-starting high-frequency high-voltage signal, thereby igniting the arc between the cutting gun and the workpiece.

[0089] Attached Fig.17 It is the circuit schematic diagram of the cutting gun switch signal detection (Ⓜ part) and the electromagnetic valve control part (Ⓝ part) during cutting in the application example part. For the cutting gun switch signal detection circuit, it is composed of CON5 socket, U1 optocoupler, D3 diode, D6 voltage regulator tube, L1 filter inductor, resistors R9 and R10, capacitors C7, C8 and C10, and 15V and 24V2 power supplies. Connect to the cutting gun switch socket in the cutting connection area of ​​the front panel of the welding machine through the CON5 plug and its connecting line, and connect the cutting gun switch control line; the cut-trig-KZ signal is connected to pin 1 of CN6, and connected to pin 1 of the CN6 socket on the control board of the present invention through its plug and its control line; obtain the detection signal of the cut-trig cutting gun switch through the cutting gun switch detection circuit of the control board of the present invention, and the signal is connected to pin 42 of the microprocessor U1B. During the cutting operation, when the cutting gun switch is not closed, the cut-trig-KZ signal is low level and the cut-trig signal is high level; when the cutting gun switch is closed, the cut-trig-KZ signal is high level and the cut-trig signal is low level. U1B can know whether the cutting gun switch is closed by detecting the high and low levels of the cut-trig signal, and perform corresponding control according to the state of the operation. For example, high-frequency control during cutting; relay output conversion control; electromagnetic valve control of compressed air output, etc. For the electromagnetic valve control circuit during cutting, it is composed of CON4 socket, U7 optocoupler, D11 diode, N-channel Q3 MOS tube, resistors R30 and R33, capacitor C24, and 15V and 24V2 power supplies. It is connected to the Cut-DCF electromagnetic valve used for cutting inside the welding machine through the CON4 plug and its connecting line, and the control of the compressed air delivery during cutting is realized by controlling the valve. The cut-gas-KZ signal is connected to the 6th pin of CN6, and is connected to the 6th pin of the CN6 socket on the control board of the present invention through its plug and its control line. Whether the cut-gas-KZ signal is low level or high level depends on the k-gas signal of the control board circuit of the present invention, which is connected to the 38th pin of U1B. When the cutting gun switch is detected to be closed, the microprocessor can output a high level k-gas signal, making the cut-gas-KZ signal low level, and the electromagnetic gas valve control circuit can be used to connect the compressed air supply path, thereby providing ion gas for igniting the arc between the cutting gun and the workpiece.

[0090] Attached Fig.12 The switching power circuit in the J1 socket can be connected to the 1st and 4th pins of the J1 socket. Fig.13The +VCC high-voltage direct current in the switching power supply circuit is supplied to the switching power supply circuit. The switching power supply circuit can generate 15V and 24V2 power supply voltages to supply other control circuits. The switching power supply circuit adopts switching power supply technology, and does not use control transformers and rectification, voltage stabilization, and filtering circuits to generate power supply voltages like ordinary welding equipment. At the same time, since the volume and weight of the switching power supply circuit are much smaller than those of general control transformers, the cost can be reduced and the DC power supply performance can be improved. For example, the switching power supply can still have a stable output voltage when the input voltage changes greatly, so it has a wide adaptability to the grid voltage, and to a large extent ensures that the welding and cutting machine of the present invention has a strong ability to resist grid voltage fluctuations. Regarding the switching power supply circuit, there are many relevant materials that can be found, and they are also relatively common. Its specific circuit and working principle will not be described here.

[0091] The above content is a detailed description of the present invention in combination with the composition and circuit principle of the welding and cutting machine of the example, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For other technicians in the technical field of the present invention, they can also make several other deductions and changes without departing from the concept of the present invention, which should be regarded as belonging to the scope of protection of the present invention.

Claims

1. A control panel of an inverter welding and cutting machine with five welding and one cutting methods, characterized in that: The control panel is installed on the front panel of the product. The control circuit part of the control panel mainly includes power supply circuit; output voltage sampling, signal conversion processing and filtering control circuit; solenoid valve control, wire feeder output connection, wire feeder voltage feedback circuit; voltage given signal circuit and current given signal circuit; overcurrent protection control and LED2 indication circuit; rectification, resistor network and filtering circuit; IGBT low-voltage side drive circuit; current parameter display and LED indication circuit; wire feeder drive circuit; Circuits for cutting gun switch detection, cutting arc ignition high-frequency control, cutting output conversion control, and cutting gas valve control; gas shielded welding gun switch detection circuit; overheat protection signal detection circuit and MCU microprocessor control circuit; the control board is provided with eight external connection sockets CN1, CN2, CN3, CN4, CN5, CN6, CN8, and CN9, which can be connected to the outside through the plugs of each socket, among which the CN2 socket is used to connect the program burner to burn the control program to the microprocessor; the CN1 socket is used to connect the power supply of the wire feeder control circuit, the 1st and 2nd pins of the CN3 socket are connected to the primary of the IGBT drive transformer through its plug and its control line, the 3rd pin of CN3 is connected to 15V, the 5th pin of CN3 is connected to the ground of 15V, and the 6th and 7th pins of CN3 are connected in series to the output ends of the current detection transformer of the primary circuit of the main transformer; the 1st and 3rd pins of the CN4 socket are connected to the switch control line of the gas shielded welding gun; The 1st and 2nd pins of the CN5 socket are respectively connected to the M+ and M- terminals of the wire feeding motor, which is a component of the wire feeding mechanism in the welding and cutting machine; the 3rd and 4th pins of CN5 are respectively connected to the positive and negative polarity terminals of the electromagnetic valve used for gas shielded welding; the 2nd pin of the CN6 socket is connected to 15V, and its 3rd pin is grounded; the 1st and 2nd pins of CN6 are connected to the switch control signal cut-trig-KZ of the cutting gun; the 4th pin of CN6 is the high-frequency control cut-HF-KZ signal during cutting; the 5th pin of CN6 is the cut-jdq-KZ signal of the relay output conversion control during cutting; the 6th pin of CN6 is the cut-gas-KZ signal of the electromagnetic valve control of compressed air during cutting; the 4th and 5th pins of the CN8 socket are connected to the control line of the overheat protection WKQ thermostat inside the welding machine; the 1st and 2nd pins of the CN9 socket are respectively connected to the U of the welding output circuit. 2f The two ends of the output voltage sampling signal, where pin 1 is the positive polarity end of the signal; The power supply circuit provides a 5V power supply and a Vdriv power supply circuit. The 5V power supply circuit is composed of a 15V power supply, an integrated voltage regulator, a capacitor and an electrolytic capacitor, and a 5V power supply can be obtained; the 15V power supply comes from the switching power supply circuit of the welding machine, which is introduced into the control board through the 3rd pin of CN3 on the control board; the other part is the Vdriv power supply circuit, whose input power comes from the CN1 plug on the control board, and it is connected to the output end of a secondary winding of the inverter main transformer in the welding machine through a connecting line; the Vdriv power supply is used to supply the electromagnetic valve control circuit and the wire feeder drive circuit; The output voltage sampling, signal conversion processing and filtering control circuit is connected to the welding output end of the machine through the CN9 plug and its control line to obtain the voltage feedback signal U 2f , this signal will participate in the feedback control of some welding methods; The solenoid valve control, wire feeder output connection, and wire feeder voltage feedback circuit are composed of a CN5 socket, a Vdriv DC power supply, resistors R5~R10, R88, a capacitor C5, a diode D1, and an N-channel MOS tube Q12; the 1st pin of CN5 is connected to the positive polarity end of the wire feeding motor, and the 2nd pin of CN5 is connected to the negative polarity end of the wire feeding motor; when there is an output voltage between M+ and M-, the wire feeding motor runs and wire feeding can be achieved, otherwise the wire feeding machine will not rotate and will not feed wire; the wire feeding voltage feedback circuit is mainly composed of resistors R5~R7 and a capacitor C5; The voltage given signal circuit in the voltage given signal circuit and the current given signal circuit is mainly composed of a 5V power supply, a variable potentiometer VR2, a diode D25, resistors R76, R76, capacitors C23 and C24; the adj2 signal is connected to pin 37 of the microprocessor U1B part, and the adj2 signal is the output voltage given signal during MIG, MAG or FLUX welding; the current given signal circuit includes a 5V power source, a variable potentiometer VR1, a diode D20, resistors R60, R61, capacitors C20 and C18; the adj1 signal end is connected to pin 22 of U1B, and the adj1 signal is the output current given signal for MMA, TIG welding and CUT cutting, or the output current given signal for MIG, MAG or FLUX welding.

2. The control panel of the inverter welding and cutting machine with five welding and one cutting methods as claimed in claim 1, characterized in that: The rectifier, resistor network and filter circuit of the control board include a current detection transformer set in the primary circuit of the main transformer, which is used to detect the primary current. The detection output signals CT1 and CT2 are rectified by a bridge rectifier circuit composed of diodes D3, D4, D13 and D14, and then filtered by a resistor network and capacitor at the rear stage to obtain i f1 Signal and i f2 signal;i f1 The signal is connected to the overcurrent protection control and LED2 indication circuit, and participates in the control of overcurrent protection; i f2 The signal is connected to pins 20 and 21 of the microprocessor U1B. The microprocessor can f2 The current feedback analog quantity is converted into digital quantity, and finally the digital quantity of the current feedback signal is obtained, which is used as the current negative feedback signal to participate in output control; The MCU microprocessor control circuit is mainly composed of an MCU microprocessor U1B, a program burning interface CN2, capacitors C3, C11, C26 and C32, a method selection button SW1, resistors R72, R28, R62, R66, 5V and 15V power supplies; the microprocessor control circuit part is mainly for sampling some signals and outputting control signals, and the control signals outputted from the 11th foot or PB and the 12th foot or PA of the microprocessor control circuit are two groups of PWM square wave pulse signals, The IGBT low-voltage side drive circuit is composed of the primary of the drive transformer, Q1 and Q2 drive chips, MOS tube drive UB1 chip, NPN transistors Q3 and Q8, diodes D5~D10, resistors R1, R11~R15, R21~R27, capacitors C7~C8 and C25, CN3 socket, 15V power supply, and PWM and OCK1 control signals; PA and PB terminals are PWM output control terminals output by the microprocessor U1B, and the PA terminal is connected to the 12th pin of the MCU microprocessor U1B; the PB terminal of the IGBT low-voltage side drive circuit is connected to the 11th pin of U1B; the PWMe terminal of the IGBT low-voltage side drive circuit is connected to the 19th pin of U1B; the OCK1 terminal is connected to the overcurrent protection control and LED2 indication circuit; Pins 1 and 2 of the CN3 socket on the control board are connected to the primary of the IGBT drive transformer through the plug and its control wire; The circuits of the cutting gun switch detection, cutting arc ignition high-frequency control, cutting output conversion control, and cutting gas valve control part mainly include 5V and 15V power supplies, resistors R50, R63, R77~R86, capacitor C30 and electrolytic capacitor C31, NPN transistors Q9, Q10, Q14, Q15 and CN6 socket; pin 2 of CN6 is connected to 15V, pin 3 is grounded, and pins 1 and 2 of CN6 are connected to the switch control signal cut-trig-KZ line of the cutting gun; the cut-trig signal in the circuit is the state detection signal of the cutting gun switch, which is connected to pin 42 of the MCU microprocessor controller U1B. The microprocessor can know whether the cutting gun switch is closed by detecting the high and low levels of the cut-trig signal and perform corresponding control; Pin 4 of the CN6 socket is the high-frequency control signal cut-HF-KZ output during cutting; whether the cut-HF-KZ signal is low level or high level depends on the k-HF control signal, and the cut-HF-KZ signal is connected to pin 40 of U1B; when it is detected that the cutting gun switch is closed, the microprocessor can output a high-level k-HF signal to turn on Q10, and the output high-frequency control signal cut-HF-KZ is low level. By using the high-frequency control circuit connected to it, the machine can generate an arc-starting high-frequency high-voltage signal, thereby igniting the arc between the cutting gun and the workpiece; The 5th pin of the CN6 socket is the control signal cut-jdq-KZ for the relay output conversion during cutting; whether the cut-jdq-KZ signal is low level or high level depends on the k-jdq signal, which is connected to the 39th pin of U1B; when it is detected that the cutting gun switch is closed, the microprocessor can output a high level k-jdq signal to turn on Q9, and the output cut-jdq-KZ is low level. By using the cutting output conversion relay control circuit connected to it, the machine can realize the output conversion of the inverter main circuit part. The 6th pin of the CN6 socket is the compressed air during cutting. The output electromagnetic valve control signal cut-gas-KZ; whether the cut-gas-KZ signal is low level or high level depends on the k-gas signal, and the cut-gas-KZ signal is connected to pin 38 of U1B; when it is detected that the cutting gun switch is closed, the microprocessor can output a high level k-gas signal to turn on Q14, and the output control signal cut-gas-KZ is low level. The electromagnetic valve control circuit connected to it can connect the machine to the compressed air supply line, thereby providing ion gas for igniting the arc between the cutting gun and the workpiece.

3. The control panel of the inverter welding and cutting machine with five welding and one cutting methods as claimed in claim 1, characterized in that: The current parameter display and LED indication circuit is mainly composed of a digital tube display meter U3, a display drive control chip U2, and seven indicator lights: OH overheat D33, MMA welding D24, TIG welding D29, CUT cutting D32, MAG welding D21, MIG welding D28, and FLUX welding D27; o1~o8 of the digital tube display meter U3 are connected to the corresponding connection points of the display drive control chip U2, wherein o1~o5 are also respectively connected to the anodes of D27, D28 and D33, D29, D24 and D32, D21, and the cathodes GR5 of D32 and D33 are connected to the corresponding connection points of U2; the cathodes GR4 of D21, D24, D27, D28 and D29 are connected to the corresponding connection points of U2; GR1, GR2 and GR3 of the digital tube display meter U3 are respectively connected to the corresponding connection points of the display drive control chip U2.

4. The control panel of the inverter welding and cutting machine with five welding and one cutting methods as claimed in claim 1, characterized in that: The overcurrent protection control and LED2 indication circuit is mainly composed of a 15V power supply, resistors R37-R43, capacitors C16 and C100, diodes D11 and D12, indicator light LED2, NPN transistor Q5, and PNP transistor Q4; i f1 The signal comes from the rectifier, resistor network and filter circuit. The input of the circuit is connected to the 6th and 7th pins of CN3, which are connected to the detection signal of the primary current of the main transformer. This current detection signal is obtained after rectification, resistor network transformation and capacitor filtering; When overcurrent occurs, LED2 lights up to indicate that an overcurrent has occurred, and at the same time, OCK1 and OCK2 overcurrent protection control signals can be obtained; the OCK2 signal is connected to pin 13 of the microprocessor U1B, and the OCK1 signal is connected to a control end of the IGBT low-voltage side drive circuit; when the microprocessor receives the OCK2 signal, it can turn off the output of the PWMe pulse output enable control signal at pin 19 of U1B, and the OCK1 signal controls the IGBT low-voltage side drive circuit, causing the IGBT drive circuit to stop outputting PWM signals, causing the inverter main circuit to stop working, making it impossible to weld or cut; when the overcurrent is relieved, the LED2 indicator light will go out before welding or cutting operations can be performed again.

5. The control panel of the inverter welding and cutting machine with five welding and one cutting methods as claimed in claim 1, characterized in that: The gas shielded welding gun switch detection circuit includes resistors R51, R52, R54, R55, R58, a diode D19, capacitors C17 and C19, an NPN transistor Q7, and a CN4 socket. CN4 is a socket for a welding gun switch connection line, which is connected to a switch control line of a gas shielded welding gun through a plug and a control line thereof. The collector of Q7, i.e., a trig signal, is connected to pin 36 of the microprocessor U1B.

6. The control panel of the inverter welding and cutting machine with five welding and one cutting methods as claimed in claim 1, characterized in that: The overheat protection signal detection circuit includes a CN8 socket, a resistor R53, a resistor R56, a resistor R57 and a capacitor C12; pins 4 and 5 of the CN8 socket are connected to the overheat protection WKQ temperature controller inside the welding machine, and WKQ is installed close to the aluminum radiator surface of the IGBT inside the machine; the OT end is the 29th pin of the microprocessor in the overheat protection signal connection.

Images