Low-power laser cutting machine air path control board and control method thereof

Abstract

The application provides a low-power laser cutting machine air path control board and a control method thereof, and belongs to the technical field of laser cutting equipment air path control. The board card comprises: a power supply input and a protection module input end connected to an external power supply, an output end connected to a DC-DC conversion module, an electromagnetic valve driving module and a signal output module; a control signal input module receives external analog signals and switching signals, and is connected to an analog signal control module; the DC-DC conversion module provides an isolated working power supply for the analog signal control module; the output end of the analog signal control module is connected to the analog signal input end of the signal output module; the electromagnetic valve driving module receives external digital control signals, and the driving output end is connected to the switching signal input end of the signal output module; and the signal output module is used for connecting external air path components. The application realizes long-line signal lossless transmission, high-temperature low-power operation, and improves control precision and reliability.

Description

Technical Field

[0001] This application belongs to the field of gas circuit control technology for laser cutting equipment, specifically relating to a gas circuit control board for a low-power laser cutting machine and its control method. Background Technology

[0002] When processing sheets of varying thicknesses and materials, low-power laser cutting machines require their gas path components to enable rapid switching between high-pressure and low-pressure gas paths and precise gas pressure regulation. In existing technologies, the control system typically uses power relays to drive solenoid valves and simulates direct-connection proportional valves with two output ports for control. However, this approach suffers from the following problems under the specific operating conditions of low-power laser cutting machines: Firstly, signal attenuation during long-distance transmission leads to insufficient control accuracy. The distance between the pneumatic circuit components and the control system can reach 30 meters. The measured attenuation rate of the 0-10V analog signal is 0.016V / m, and the 10V signal will be reduced to approximately 9.5V after transmission. This results in a decrease of about 5% in the proportional valve control accuracy, failing to meet the 0.1MPa level pneumatic pressure regulation requirements. Secondly, the general-purpose signal amplifier does not consider the strong interference and high-temperature environment of laser cutting, easily introducing new noise.

[0003] Secondly, the high-temperature, enclosed environment caused the drive components to overheat and fail. The circuit board was installed close to the cutting head along with the air circuit components, operating in an environment with a temperature reaching 60°C. Furthermore, the space was sealed, without heat sinks or fans. MOSFETs with a standard 2-3 times current margin experienced junction temperatures exceeding 75°C after 8 hours of continuous operation under natural cooling at 60°C, failing to meet the requirements for extended operation.

[0004] Secondly, the system's port resources are limited and susceptible to strong electromagnetic interference. Low-power cutting systems have insufficient analog output ports but more than enough digital output ports; purchasing additional expansion modules is costly and wasteful of space. Simultaneously, interference from machine tool movement, high-frequency discharge, and relay back electromotive force within the workshop causes analog signal drift of ±0.2V, further reducing control accuracy.

[0005] In summary, existing technologies have not yet provided a dedicated gas path control solution that can simultaneously address the three mutually restrictive technical problems of long-line attenuation, high-temperature heat dissipation, port limitation, and electromagnetic interference. Summary of the Invention

[0006] In a first aspect, embodiments of this application provide a pneumatic control board for a low-power laser cutting machine, including a power input and protection module, a control signal input module, a DC-DC conversion module, an analog signal control module, a solenoid valve drive module, and a signal output module; The input terminal of the power supply input and protection module is connected to an external power source, and the output terminal of the power supply input and protection module is connected to the input terminal of the DC-DC conversion module, the power input terminal of the solenoid valve drive module, and the power supply terminal of the signal output module. The input terminal of the control signal input module is used to receive analog signals within a preset voltage range and switch signals of a first preset voltage value. The output terminal of the control signal input module is connected to the signal input terminal of the analog signal control module. The output of the DC-DC converter module is connected to the power supply of the analog signal control module to provide the analog signal control module with a second preset voltage value. The output terminal of the analog signal control module is connected to the analog signal input terminal of the signal output module; The control signal input terminal of the solenoid valve drive module is used to receive external digital control signals, and the drive output terminal of the solenoid valve drive module is connected to the switch signal input terminal of the signal output module. The interface of the signal output module is used to connect to the high and low level solenoid valves and high and low level proportional valves of the external pneumatic circuit components.

[0007] Furthermore, the power supply input and protection module includes a main input slow-blow fuse F_T1, a first-stage TVS transistor TVS_D1, a reverse connection protection MOSFET Q2, a second-stage TVS transistor TVS_D2, three branch protection circuits, and three LED status indicator circuits. The first terminal of the main input slow-blow fuse F_T1 is connected to the positive terminal of the external power supply, and the second terminal is connected to the first terminal of the first-stage TVS transistor TVS_D1, serving as the one-time power supply output terminal; the second terminal of the first-stage TVS transistor TVS_D1 is connected to the ground of the external power supply. The reverse polarity protection MOSFET Q2 is an N-channel MOSFET, with its drain connected to the external power supply ground, its source connected to the board system ground, and its gate connected to the primary power supply output terminal through a voltage divider resistor network. The primary power supply output terminal is connected to all three branch protection circuits; The three branch protection circuits are the first branch, the second branch, and the third branch, respectively; The first branch is equipped with a medium-speed fuse F_MD2. The first end of the medium-speed fuse F_MD2 is connected to the one-time power supply output terminal, and the second end is connected to the proportional valve branch power supply terminal. The second branch is equipped with a medium-speed fuse F_MD3. The first end of the medium-speed fuse F_MD3 is connected to the one-time power supply output terminal, and the second end is connected to the power supply terminal of the solenoid valve branch. The third branch is equipped with a self-resetting fuse F_PTC4. The first end of the self-resetting fuse F_PTC4 is connected to the one-time power supply output terminal, and the second end is connected to the power supply terminal of the control circuit branch. The second-stage TVS transistor, TVS_D2, is connected in parallel between the power supply terminal of the control circuit branch and the system ground of the board. The three LED status indicator circuits are respectively connected between the power supply terminals of the proportional valve branch, the solenoid valve branch, and the control circuit branch, and the system ground of the board.

[0008] Furthermore, the analog signal control module includes a clamping protection circuit, a first operational amplifier U1A, a linear optocoupler U2, a second operational amplifier U1B, a signal reconstruction and attenuation compensation circuit, and a channel switching unit; The clamping protection circuit includes a resistor R1 and a transient suppression diode D2; The first terminal of resistor R1 is connected to the positive terminal of the analog input, the second terminal of resistor R1 is connected to the first terminal of transient suppression diode D2, the second terminal of transient suppression diode D2 is connected to the negative terminal of the analog input, and grounded; The non-inverting input of the first operational amplifier U1A is connected to the output of the clamping protection circuit. The inverting input of the first operational amplifier U1A is connected to a resistor R5 and is connected to a linear optocoupler U2. The output of the first operational amplifier U1A is connected to a resistor R3. The other end of the resistor R5 is grounded. The linear optocoupler U2 includes an LED, a feedback photodiode PD1, and an output photodiode PD2; The positive terminal of the LED is connected to the other end of resistor R3, the negative terminal of the LED is grounded, the negative terminal of the output photodiode PD2 is connected to the signal reconstruction and attenuation compensation circuit, and the positive terminal of the output photodiode PD2 is grounded; the negative terminal of the feedback photodiode PD1 is connected to the positive terminal of the second power supply, and the positive terminal of the feedback photodiode PD1 is connected to the inverting input terminal of the first operational amplifier U1A and resistor R5. The signal reconstruction and attenuation compensation circuit includes a second operational amplifier U1B, a resistor R4, and an adjustable resistor R2. The first terminal of the resistor R4 is connected to the negative terminal of the output photodiode PD1 of the linear optocoupler U2 and the inverting input terminal of the second operational amplifier U1B. The non-inverting input terminal of the second operational amplifier U1B is grounded. The output terminal of the second operational amplifier U1B is connected to the first terminal of the adjustable resistor R2. The second terminal of the adjustable resistor R2 is connected to the second terminal of the resistor R4. The output of the second operational amplifier U1B is also connected to the channel switching unit; The channel switching unit uses a signal relay, which has a common terminal, normally open contact, normally closed contact, first selection terminal and second selection terminal; The first and second selection terminals are used to receive control signals from external digital output ports. The normally open and normally closed contacts serve as the output terminals of the channel switching unit and are respectively connected to the two analog signal input terminals of the signal output module.

[0009] Furthermore, the solenoid valve drive module includes an optocoupler U3, a drive MOSFET Q1, and a freewheeling diode D3; The input side of optocoupler U3 is used to receive external digital control signals; The gate of the driving MOSFET Q1 is connected to resistors R7 and R8, and the other end of resistor R7 is connected to the output side of optocoupler U3. The source of the driving MOSFET Q1 is connected to the other end of the resistor R8 and grounded, and the drain of the driving MOSFET Q1 is connected to the negative terminal of the external solenoid valve. The positive terminal of the freewheeling diode D3 is connected to the drain of the driving MOSFET Q1, and the negative terminal of the freewheeling diode D3 is connected to the positive power supply terminal of the external solenoid valve. The ratio of the rated current of the driving MOSFET Q1 to the rated current of the driven solenoid valve is greater than or equal to 6.

[0010] Furthermore, the control signal input module uses waterproof terminals, and the port spacing between analog signals and digital signals is set to a preset terminal spacing. The signal output module includes four plug terminals, which are used to connect to the high-pressure solenoid valve, low-pressure solenoid valve, high-pressure proportional valve and low-pressure proportional valve of the external pneumatic circuit components, respectively.

[0011] Secondly, embodiments of this application also provide a control method based on the air circuit control board of a low-power laser cutting machine described in the first aspect, comprising the following steps: S1. The power input and protection module provides graded protection and conversion of the input power supply to provide power supply voltage to each module; S2. Receive external analog signals and digital signals through the control signal input module; S3. The analog signal control module performs clamping protection, isolation transmission, attenuation compensation reconstruction, and channel switching on the received analog signal to generate the reconstructed analog control signal. S4. Receive external digital control signals through the solenoid valve drive module, and generate solenoid valve drive signals to drive the solenoid valve on and off after isolation; S5. The reconstructed analog control signal and solenoid valve drive signal are output to the proportional valve and solenoid valve of the external pneumatic circuit component through the signal output module.

[0012] Furthermore, the specific steps of step S1 are as follows: S11. After the positive terminal of the external power supply passes through the main input slow-blow fuse F_T1, the first-stage TVS tube TVS_D1 clamps the input surge voltage, generating a primary power supply output. S12. The reverse connection protection MOSFET Q2 automatically turns on according to the primary power supply output, connecting the external power ground to the board system ground to achieve reverse connection protection; S13. The primary power supply is output into three paths: the first path is output to the proportional valve branch power supply terminal via the medium-speed fuse F_MD2; the second path is output to the solenoid valve branch power supply terminal via the medium-speed fuse F_MD3; and the third path is output to the control circuit branch power supply terminal via the self-resetting fuse F_PTC4. S14. The second-stage TVS transistor TVS_D2 performs secondary overvoltage clamping on the power supply terminal of the control circuit branch to suppress the induced voltage surge generated by the operation of the solenoid valve. S15. Determine whether the power supply of the corresponding branch is normal by checking the on / off status of the three LED status indicator circuits.

[0013] Furthermore, the specific steps of step S3 are as follows: S31. After the analog signal is transmitted through a cable with a preset transmission distance, it enters the board. The input voltage is clamped to below the safe threshold by the resistor R1 and transient suppression diode D2 in the clamping protection circuit, and the clamping voltage signal is output. S32. The clamping voltage signal is sent to the non-inverting input of the first operational amplifier U1A. The first operational amplifier U1A drives the LED of the linear optocoupler U2 through resistor R3, so that the LED current is linearly related to the input voltage. S33. The feedback photodiode PD1 of the linear optocoupler U2 receives the optical signal and generates a feedback photocurrent. The feedback photocurrent flows from the inverting input terminal of the first operational amplifier U1A through the feedback photodiode PD1 to ground, and together with the current flowing to ground through resistor R5, satisfies the virtual short balance and establishes linear isolation transmission. S34. The output photodiode PD2 of the linear optocoupler U2 generates a photocurrent proportional to the input side. This photocurrent flows through resistor R4 and generates a voltage at the inverting input terminal of the second operational amplifier U1B. S35. The second operational amplifier U1B, together with resistor R4 and adjustable resistor R2, constitutes a proportional amplifier circuit. The actual gain of the proportional amplifier circuit is... Determined by the following formula:

[0014] S36. Calculate the required target compensation gain based on the measured attenuation data of long-distance transmission. :

[0015] in, This is the measured voltage after long-distance transmission. The target voltage that needs to be rebuilt; Adjust the resistance value of the adjustable resistor R2 to This makes the actual gain Equal to target compensation gain ; S37. The output terminal of the second operational amplifier U1B outputs the reconstructed analog control signal, which serves as the input signal for the channel switching unit; S38. The channel switching unit receives a time-division control signal from an external digital output port: When the time-sharing control signal is at the first level, the signal relay will connect the reconstructed analog control signal to the first proportional valve interface of the signal output module. When the time-sharing control signal is at the second level, the signal relay will connect the reconstructed analog control signal to the second proportional valve interface; S39. Repeat steps S31 to S38 to realize time-sharing control of the dual proportional valve by a single analog signal based on the periodic change of the time-sharing control signal.

[0016] Furthermore, the specific steps of step S4 are as follows: S41. The solenoid valve drive module receives the control signal from the external digital output port and uses the signal to drive the input-side light-emitting diode of the optocoupler U3; S42. The phototransistor on the output side of optocoupler U3 is turned on, and the isolated drive level is applied to the gate of drive MOS transistor Q1 through resistor R7 to determine the drive level. When the drive level is high, proceed to step S43; When the drive level is low, proceed to step S44; S43. Drive MOSFET Q1 to conduct, its drain is pulled to ground, the negative terminal of the external solenoid valve is energized, the solenoid valve is activated, and proceed to step S45. S44. When the drive MOSFET Q1 is turned off, the external solenoid valve is de-energized and reset. The reverse electromotive force generated by the coil of the external solenoid valve forms a freewheeling circuit through the freewheeling diode D3, clamping the spike voltage at the supply voltage and protecting the drive MOSFET Q1. S45. Set the rated current of the driving MOSFET Q1 to a preset multiple or more than the rated current of the driven solenoid valve. By using the redundancy of the rated current of the driving MOSFET Q1 exceeding the actual load current, the operating junction temperature of the driving MOSFET Q1 under the preset high temperature ambient temperature and without forced heat dissipation is suppressed. The specific steps of step S5 are as follows: S51. The signal output module receives the reconstructed analog signal output by the channel switching unit in step S38, and transmits it to the external high-pressure proportional valve and low-pressure proportional valve through the first analog output port and the second analog output port, respectively. S52. The signal output module receives the solenoid valve drive signal generated in step S43 and transmits it to the external high-pressure solenoid valve and low-pressure solenoid valve through the first switch output port and the second switch output port, respectively. S53. The signal output module is connected to the corresponding interface of the external pneumatic circuit component through four plug-in terminals in a one-time plug-in connection to complete the output of all control signals.

[0017] Furthermore, the process for determining the preset multiple in step S45 is as follows: S451. Based on the rated current of the solenoid valve, select several samples with different current multiples and conduct continuous working temperature rise tests under preset high temperature environment and natural heat dissipation conditions. S452. Record the operating junction temperature of the driving MOSFET Q1 at each multiplier, and calculate the temperature difference between the operating junction temperature and the ambient temperature:

[0018] in, For working temperature, Ambient temperature; S453. Analyze the curve of temperature difference as the multiple increases, identify the inflection point where the rate of temperature difference decreases, and take the multiple corresponding to the inflection point as the multiple of temperature rise suppression inflection point; S454. Select the lower limit of the multiple corresponding to the temperature rise suppression inflection point as the preset multiple; S455. Select the rated current specification of the driving MOSFET Q1 according to the preset multiple: Load current is When selecting a rated current ≥ preset multiple × MOSFET.

[0019] As can be seen from the above technical solutions, this application has the following advantages: The low-power laser cutting machine pneumatic control board and its control method provided in this application achieve lossless reconstruction of analog signals after 30-meter long-line transmission through attenuation compensation circuit and linear optocoupler isolation, improving control accuracy and meeting pneumatic pressure regulation requirements. By selecting MOSFETs with 6-10 times extreme current redundancy and a heatsink-free design, low-temperature operation in a 60℃ high-temperature, enclosed, airless environment is achieved, solving the problem of overheating failure of driving devices. A hierarchical protection architecture is adopted, featuring slow-blow fuse for the total input, medium-speed fuse for the inductive load branch, and self-recovery for the control circuit branch, combined with low-on-resistance MOSFET reverse connection protection. The design achieves protection against surge current, inductive load back electromotive force, and reverse power connection in a 30-meter long power supply environment, while controlling the voltage drop of the power supply circuit within the allowable range, ensuring that the drive voltage at the end of the long line is maintained above 21V, thus guaranteeing the stable operation of the pneumatic circuit components. Through the control logic of single-channel analog quantity time-sharing dual valve switching, the system's redundant digital quantity ports are used to control dual proportional valves, saving costs per unit without increasing analog quantity ports and expansion modules. Through plug-in interfaces and visual fault indication, the pneumatic circuit components are plug-and-play, shortening on-site installation time and simplifying troubleshooting. Attached Figure Description

[0020] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the air circuit control board for the low-power laser cutting machine of the present invention.

[0022] Figure 2 This is a circuit diagram of the power input and protection module of the present invention.

[0023] Figure 3 This is a circuit diagram of the analog signal control module of the present invention.

[0024] Figure 4 This is a circuit diagram of the solenoid valve drive module of the present invention.

[0025] Figure 5 This is a schematic diagram of the circuit principle of the DC-DC conversion module of the present invention.

[0026] Figure 6 This is a flowchart illustrating the control method of the air circuit control board for a low-power laser cutting machine according to the present invention. Detailed Implementation

[0027] Various embodiments of this disclosure will be described more fully in the following detailed description of the pneumatic control board for a low-power laser cutting machine. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.

[0028] This embodiment provides a low-power laser cutting machine air circuit control board that enables long-distance lossless signal transmission, high-temperature and low-power operation, and saves hardware costs by using time-division switching logic.

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1 The diagram shown is a schematic of a pneumatic control board for a low-power laser cutting machine in a specific embodiment. The board includes a power input and protection module, a control signal input module, a DC-DC conversion module, an analog signal control module, a solenoid valve drive module, and a signal output module. The input terminal of the power supply input and protection module is connected to an external power source, and the output terminal of the power supply input and protection module is connected to the input terminal of the DC-DC conversion module, the power input terminal of the solenoid valve drive module, and the power supply terminal of the signal output module. It should be noted that the power input and protection module adopts MOSFET reverse connection protection and graded fuse protection to ensure that the proportional valve drive voltage can still be maintained above the minimum operating threshold (such as 21V) at the end of the 30-meter long power supply line. The input terminal of the control signal input module is used to receive analog signals within a preset voltage range and switch signals of a first preset voltage value. The output terminal of the control signal input module is connected to the signal input terminal of the analog signal control module. It should be noted that the physically isolated terminal design and wide spacing of the control signal input module can prevent accidental operation and improve the safety of the system. The output of the DC-DC converter module is connected to the power supply of the analog signal control module to provide the analog signal control module with a second preset voltage value. It should be noted that the isolated dual power supply blocks ground loop interference, enabling high-density integration of signals and drivers on the same board without mutual interference. The output terminal of the analog signal control module is connected to the analog signal input terminal of the signal output module; It should be noted that the analog signal control module achieves electrical isolation and reconstruction of the signal through a linear optocoupler and a resistor network, which can compensate for cable loss. The control signal input terminal of the solenoid valve drive module is used to receive external digital control signals, and the drive output terminal of the solenoid valve drive module is connected to the switch signal input terminal of the signal output module. It should be noted that the solenoid valve drive module uses a drive MOSFET that has no mechanical wear, and with the help of current redundancy design, it achieves low temperature rise operation under conditions without heat sink. The interface of the signal output module is used to connect to the high and low level solenoid valves and high and low level proportional valves of the external pneumatic circuit components. It should be noted that the standardized plug-in interface of the signal output module enables plug-and-play functionality for the pneumatic circuit components, improving the efficiency of equipment installation and maintenance.

[0031] This embodiment achieves lossless transmission of long-distance signals through attenuation compensation and ensures stable operation at high temperatures through current redundancy; it also reduces hardware costs and port usage by using a single analog quantity to control a dual proportional valve in a time-division manner.

[0032] Furthermore, as a refinement and extension of the specific implementation methods described above, and to fully illustrate the specific implementation process in this embodiment, another low-power laser cutting machine pneumatic control board is provided, such as... Figure 1 As shown, the board includes a power input and protection module, a control signal input module, a DC-DC conversion module, an analog signal control module, a solenoid valve drive module, and a signal output module. The input terminal of the power supply input and protection module is connected to an external power source, and the output terminal of the power supply input and protection module is connected to the input terminal of the DC-DC conversion module, the power input terminal of the solenoid valve drive module, and the power supply terminal of the signal output module. The input terminal of the control signal input module is used to receive analog signals within a preset voltage range and switch signals of a first preset voltage value. The output terminal of the control signal input module is connected to the signal input terminal of the analog signal control module. The output of the DC-DC converter module is connected to the power supply of the analog signal control module to provide the analog signal control module with a second preset voltage value. The output terminal of the analog signal control module is connected to the analog signal input terminal of the signal output module; The control signal input terminal of the solenoid valve drive module is used to receive external digital control signals, and the drive output terminal of the solenoid valve drive module is connected to the switch signal input terminal of the signal output module. The interface of the signal output module is used to connect to the high and low level solenoid valves and high and low level proportional valves of the external pneumatic circuit components. like Figure 2 As shown, the power supply input and protection module includes a main input slow-blow fuse F_T1, a first-stage TVS transistor TVS_D1, a reverse connection protection MOSFET Q2, a second-stage TVS transistor TVS_D2, three branch protection circuits, and three LED status indicator circuits. The first terminal of the main input slow-blow fuse F_T1 is connected to the positive terminal of the external power supply (24V), and the second terminal is connected to the first terminal of the first-stage TVS transistor TVS_D1, serving as the one-time power supply output terminal; the second terminal of the first-stage TVS transistor TVS_D1 is connected to the external power supply ground (i.e., 0V). The reverse polarity protection MOSFET Q2 is an N-channel MOSFET, with its drain connected to the external power supply ground, its source connected to the board system ground, and its gate connected to the primary power supply output terminal through a voltage divider resistor network. The voltage divider resistor network includes resistor R11, resistor R13, and Zener diode D4; The gate of the reverse-connection protected MOSFET Q2 is connected to the negative terminals of resistors R11 and R13 and Zener diode D4. The source is connected to the other end of resistor R13 and the positive terminal of Zener diode D4, and grounded. The other end of resistor R11 is connected to the primary power supply output terminal. It should be noted that the on-resistance of the reverse-connection MOSFET Q2 is... The voltage drop is 5.5mΩ; under a load current of 10A, the voltage drop is given by the formula. The calculated and measured voltage drop is 55mV, which ensures that the voltage at the end of the long-line power supply is maintained above 21V. Compared to traditional reverse polarity protection diodes, such as the 1N5401, which generate approximately 0.7V voltage drop, the reverse polarity protection MOSFET Q2 in this application uses an N-channel MOSFET, A04410. =5.5mΩ, and the voltage drop at a current of 10A is only I²×R=10×0.0055=0.055V=55mV; far lower than the approximately 0.7V of a traditional diode, thus ensuring that the voltage at the end of a long power supply line is maintained above 21V; The primary power supply output terminal is connected to all three branch protection circuits; The three branch protection circuits are the first branch, the second branch, and the third branch, respectively; The first branch is equipped with a medium-speed fuse F_MD2. The first end of the medium-speed fuse F_MD2 is connected to the primary power supply output terminal 24V_PV_H / L, and the second end is connected to the proportional valve branch power supply terminal. The second branch is equipped with a medium-speed fuse F_MD3. The first end of the medium-speed fuse F_MD3 is connected to the one-time power supply output terminal 24V_SV_H / L, and the second end is connected to the power supply terminal of the solenoid valve branch. The third branch is equipped with a resettable fuse F_PTC4. The first end of the resettable fuse F_PTC4 is connected to the one-time power supply output terminal 24V_3, and the second end is connected to the power supply terminal of the control circuit branch. The second-stage TVS transistor, TVS_D2, is connected in parallel between the power supply terminal of the control circuit branch and the system ground of the board. The three LED status indicator circuits are respectively connected between the power supply terminals of the proportional valve branch, the solenoid valve branch, and the control circuit branch, and the system ground of the board. The three-way LED status indicator circuit includes a first indicator circuit, a second indicator circuit, and a third indicator circuit; The first indicator circuit is equipped with a first LED LED1. The positive terminal of the first LED LED1 is connected to the power supply terminal of the proportional valve branch, and the negative terminal is connected to a resistor R12. The other end of the resistor R12 is grounded. The second indicator branch is equipped with a second LED light LED2. The positive terminal of the second LED light LED2 is connected to the power supply terminal of the solenoid valve branch, and the negative terminal is connected to a resistor R9. The other end of the resistor R9 is grounded. The third indicator branch is equipped with a third LED light LED3. The positive terminal of the third LED light LED3 is connected to the power supply terminal of the control circuit branch, and the negative terminal is connected to a resistor R10. The other end of the resistor R10 is grounded. like Figure 5 As shown, the DC-DC conversion module includes two stages. The first stage is a DC-DC step-down unit, which steps down the 24V input to 15V. For example, the DC-DC step-down unit can be an LM2596-15. The second stage is a DC-DC isolation conversion unit, which converts the 15V to a ±15V isolated power supply. For example, the DC-DC isolation conversion unit can be a B0515S-1W, which provides a low-noise dual power supply for the operational amplifier in the analog signal control module. like Figure 3 As shown, the analog signal control module includes a clamping protection circuit, a first operational amplifier U1A, a linear optocoupler U2, a second operational amplifier U1B, a signal reconstruction and attenuation compensation circuit, and a channel switching unit. The clamping protection circuit includes a resistor R1 and a transient suppression diode D2; The first terminal of resistor R1 is connected to the positive analog input port DA+, the second terminal of resistor R1 is connected to the first terminal of transient suppression diode D2, the second terminal of transient suppression diode D2 is connected to the negative analog input port DA-, and grounded; The first end of resistor R1 is also connected to capacitor C1, and the other end of capacitor C1 is grounded; The non-inverting input of the first operational amplifier U1A is connected to the output of the clamping protection circuit (i.e., the first end of resistor R1). The inverting input of the first operational amplifier U1A is connected to resistor R5 and is connected to the linear optocoupler U2. The output of the first operational amplifier U1A is connected to resistor R3. The other end of resistor R5 is grounded. The positive power supply terminal of the first operational amplifier U1A is connected to a +15V isolated power supply, and the negative power supply terminal of the first operational amplifier U1A is connected to a -15V isolated power supply. The linear optocoupler U2 includes an LED, a feedback photodiode PD1, and an output photodiode PD2; The positive terminal of the LED is connected to the other end of resistor R3, the negative terminal of the LED is grounded, the negative terminal of the output photodiode PD2 is connected to the signal reconstruction and attenuation compensation circuit, and the positive terminal of the output photodiode PD2 is grounded; the negative terminal of the feedback photodiode PD1 is connected to the positive terminal of the second power supply, i.e., the +15V isolation power supply, and the positive terminal of the feedback photodiode PD1 is connected to the inverting input terminal of the first operational amplifier U1A and resistor R5. The signal reconstruction and attenuation compensation circuit includes a second operational amplifier U1B, a resistor R4, and an adjustable resistor R2. The first terminal of the resistor R4 is connected to the negative terminal of the output photodiode PD1 of the linear optocoupler U2 and the inverting input terminal of the second operational amplifier U1B. The non-inverting input terminal of the second operational amplifier U1B is grounded. The output terminal of the second operational amplifier U1B is connected to the first terminal of the adjustable resistor R2. The second terminal of the adjustable resistor R2 is connected to the second terminal of the resistor R4. The inverting input terminal of the second operational amplifier U1B is also connected to a capacitor C2, and the other end of the capacitor C2 is connected to the output terminal of the second operational amplifier U1B. The output of the second operational amplifier U1B is also connected to the channel switching unit; The channel switching unit uses a signal relay, which has a common terminal, normally open contact, normally closed contact, first selection terminal and second selection terminal; The first and second selection terminals are used to receive control signals from external digital output ports. Specifically, the first selection terminal is connected to the digital output port CH_SEL+, and the second selection terminal is connected to the digital output port CH_SEL-. The normally open and normally closed contacts serve as the output terminals of the channel switching unit and are respectively connected to the two analog signal input terminals of the signal output module; that is, the normally open contact is connected to the analog signal input terminal L_DA+, and the normally closed contact is connected to the analog signal input terminal H_DA+. like Figure 4 As shown, the solenoid valve drive module includes an optocoupler U3, a drive MOSFET Q1, and a freewheeling diode D3; The input side of optocoupler U3 is used to receive external digital control signals; the positive terminal of the LED of optocoupler U3 is connected to resistor R6, the other end of resistor R6 is connected to the digital control signal H / L_SV+, and the negative terminal of the LED of optocoupler U3 is connected to the digital control signal H / L_SV-. The gate of the driving MOSFET Q1 is connected to resistors R7 and R8, and the other end of resistor R7 is connected to the output side of optocoupler U3; that is, the emitter of the phototransistor of optocoupler U3 is connected to resistor R7, and the collector of the phototransistor of optocoupler U3 is connected to the primary power supply output terminal 24V_3. The source of the driving MOSFET Q1 is connected to the other end of resistor R8 and grounded. The drain of the driving MOSFET Q1 is connected to the negative terminal of the external solenoid valve. The negative terminal of the external solenoid valve is connected to the digital control signal SV_CTRL_H / L. The positive terminal of the freewheeling diode D3 is connected to the drain of the driving MOSFET Q1, and the negative terminal of the freewheeling diode D3 is connected to the positive power supply terminal of the external solenoid valve; the positive power supply terminal of the external solenoid valve is connected to the primary power supply output terminal 24V_SV_H / L. The ratio of the rated current of the driving MOSFET Q1 to the rated current of the driven solenoid valve is greater than or equal to 6. The control signal input module uses waterproof terminals, such as spring-loaded straight terminals with IP65 protection, and sets the port spacing between analog signals and digital signals to a preset terminal spacing, such as 8mm. The signal output module includes four plug terminals, which are used to connect to the high-pressure solenoid valve, low-pressure solenoid valve, high-pressure proportional valve and low-pressure proportional valve of the external pneumatic circuit components, respectively. The signal output module consists of four plug-in terminals, which are used to connect to external high-pressure proportional valves, low-pressure proportional valves, high-pressure solenoid valves, and low-pressure solenoid valves, respectively.

[0033] like Figure 6 As shown, the following is an embodiment of the control method of the gas circuit control board for a low-power laser cutting machine provided in this disclosure. This method belongs to the same inventive concept as the gas circuit control board for the low-power laser cutting machine in the above embodiments. For details not described in detail in the embodiments of the control method of the gas circuit control board for the low-power laser cutting machine, please refer to the embodiments of the gas circuit control board for the low-power laser cutting machine described above.

[0034] The method includes the following steps: S1. The power input and protection module provides graded protection and conversion of the input power supply to provide power supply voltage to each module; It should be noted that through multi-level protection, power grid fluctuations and surges are filtered out, preventing the system from crashing due to power supply problems; S2. Receive external analog signals and digital signals through the control signal input module; It should be noted that by acquiring external analog and digital signals, the control system commands are imported into the board for processing. S3. The analog signal control module performs clamping protection, isolation transmission, attenuation compensation reconstruction, and channel switching on the received analog signal to generate the reconstructed analog control signal. It should be noted that the clamping protection in this step prevents external high voltage and electromagnetic interference from entering the circuit. The attenuation compensation and reconstruction calculation compensates for the signal loss caused by the long cable, so as to obtain the real control command. Dual valve control is realized through channel switching, which improves resource utilization. S4. Receive external digital control signals through the solenoid valve drive module, and generate solenoid valve drive signals to drive the solenoid valve on and off after isolation; It should be noted that by using optocoupler isolation and MOSFET switching drive, the digital control signal is converted into a high-current drive signal that can directly drive the solenoid valve. S5. The reconstructed analog control signal and solenoid valve drive signal are output to the proportional valve and solenoid valve of the external pneumatic circuit component through the signal output module, respectively. It should be noted that by summing and outputting the processed analog quantity and the driven digital quantity, the final precise control of the proportional valve and solenoid valve in the pneumatic circuit assembly is achieved.

[0035] This embodiment achieves lossless long-distance signal transmission through attenuation compensation, ensures stable operation at high temperatures through current redundancy, saves hardware costs by adopting time-division switching logic, and improves installation convenience.

[0036] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process in this embodiment, another control method for a low-power laser cutting machine gas circuit control board is provided, which includes the following steps: S1. The power input and protection module provides graded protection and conversion of the input power supply to provide power supply voltage to each module; The specific steps of step S1 are as follows: S11. After the positive terminal of the external power supply passes through the main input slow-blow fuse F_T1, the first-stage TVS tube TVS_D1 clamps the input surge voltage, generating a primary power supply output. S12. The reverse connection protection MOSFET Q2 automatically turns on according to the primary power supply output, connecting the external power ground to the board system ground to achieve reverse connection protection; S13. The primary power supply is output into three paths: the first path is output to the proportional valve branch power supply terminal via the medium-speed fuse F_MD2; the second path is output to the solenoid valve branch power supply terminal via the medium-speed fuse F_MD3; and the third path is output to the control circuit branch power supply terminal via the self-resetting fuse F_PTC4. S14. The second-stage TVS transistor TVS_D2 performs secondary overvoltage clamping on the power supply terminal of the control circuit branch to suppress the induced voltage surge generated by the operation of the solenoid valve. S15. Determine whether the power supply of the corresponding branch is normal by checking the on / off status of the three LED status indicator circuits; S2. Receive external analog signals and digital signals through the control signal input module; S3. The analog signal control module performs clamping protection, isolation transmission, attenuation compensation reconstruction, and channel switching on the received analog signal to generate the reconstructed analog control signal. The specific steps of step S3 are as follows: S31. After the analog signal is transmitted through a cable with a preset transmission distance (e.g., 30 meters), it enters the board. The input voltage is clamped to below the safe threshold by the resistor R1 and transient suppression diode D2 in the clamping protection circuit, and the clamping voltage signal is output. It should be noted that when the 0-10V analog input port is mistakenly connected to a 24V power supply, the 1.5kΩ resistor R1 and the SMBJ15CA transient suppression diode D2 form a clamping protection circuit, limiting the voltage at the non-inverting input of the first operational amplifier U1A to approximately 17V. At this time, the power consumption of resistor R1 is approximately 32.7mW, and the power consumption of transient suppression diode D2 is approximately 79.4mW, both of which are far less than the rated values ​​of the devices and can withstand the misconnection condition for a long time. S32. The clamping voltage signal is sent to the non-inverting input of the first operational amplifier U1A. The first operational amplifier U1A drives the LED of the linear optocoupler U2 through resistor R3, so that the LED current is linearly related to the input voltage. S33. The feedback photodiode PD1 of the linear optocoupler U2 receives the optical signal and generates a feedback photocurrent. The feedback photocurrent flows from the inverting input terminal of the first operational amplifier U1A through the feedback photodiode PD1 to ground, and together with the current flowing to ground through resistor R5, satisfies the virtual short balance and establishes linear isolation transmission. S34. The output photodiode PD2 of the linear optocoupler U2 generates a photocurrent proportional to the input side. This photocurrent flows through resistor R4 and generates a voltage at the inverting input terminal of the second operational amplifier U1B. S35. The second operational amplifier U1B, together with resistor R4 and adjustable resistor R2, constitutes a proportional amplifier circuit. The actual gain of the proportional amplifier circuit is... Determined by the following formula:

[0037] It should be noted that after 30 meters of long-distance transmission, the measured input 10V signal dropped to 9.5V, an attenuation rate of 5%; the required compensation gain... Combined with the transmission characteristics of linear optical couplers The theoretical value of the adjustable resistor R2 for compensation is derived from the circuit diagram: Substituting R4=330kΩ and R5=330kΩ, we get R2=17.36kΩ; therefore, we set the adjustable resistor R2 to a 20kΩ sliding rheostat to achieve adjustable gain in the range of 1~1.0606. S36. Calculate the required target compensation gain based on the measured attenuation data of long-distance transmission. :

[0038] in, This is the measured voltage after long-distance transmission. The target voltage that needs to be rebuilt; Adjust the resistance value of the adjustable resistor R2 to This makes the actual gain Equal to target compensation gain ; S37. The output terminal of the second operational amplifier U1B outputs the reconstructed analog control signal, which serves as the input signal for the channel switching unit; S38. The channel switching unit receives a time-division control signal from an external digital output port: When the time-sharing control signal is at the first level, the signal relay will connect the reconstructed analog control signal to the first proportional valve interface of the signal output module. When the time-sharing control signal is at the second level, the signal relay will connect the reconstructed analog control signal to the second proportional valve interface; S39. Repeat steps S31 to S38 to realize time-sharing control of the dual proportional valve by a single analog signal based on the periodic change of the time-sharing control signal. S4. Receive external digital control signals through the solenoid valve drive module, and generate solenoid valve drive signals to drive the solenoid valve on and off after isolation; The specific steps of step S4 are as follows: S41. The solenoid valve drive module receives the control signal from the external digital output port and uses the signal to drive the input-side light-emitting diode of the optocoupler U3; S42. The phototransistor on the output side of optocoupler U3 is turned on, and the isolated drive level is applied to the gate of drive MOS transistor Q1 through resistor R7 to determine the drive level. When the drive level is high, proceed to step S43; When the drive level is low, proceed to step S44; S43. Drive MOSFET Q1 to conduct, its drain is pulled to ground, the negative terminal of the external solenoid valve is energized, the solenoid valve is activated, and proceed to step S45. S44. When the drive MOSFET Q1 is turned off, the external solenoid valve is de-energized and reset. The reverse electromotive force generated by the coil of the external solenoid valve forms a freewheeling circuit through the freewheeling diode D3, clamping the spike voltage at the supply voltage and protecting the drive MOSFET Q1. S45. Set the rated current of the driving MOSFET Q1 to a preset multiple or more than the rated current of the driven solenoid valve. By using the redundancy of the rated current of the driving MOSFET Q1 exceeding the actual load current, the operating junction temperature of the driving MOSFET Q1 under the preset high temperature ambient temperature and without forced heat dissipation is suppressed. The process of determining the preset multiple in step S45 is as follows: S451. Based on the rated current of the solenoid valve, select several samples with different current multiples and conduct continuous working temperature rise tests under preset high temperature environment (e.g., 60℃) and natural heat dissipation conditions. For example, a MOSFET with a typical current margin of 2-3 times reaches a junction temperature of over 75°C after 8 hours of natural heat dissipation at 60°C. Using a solenoid valve with a rated current of 800mA as a benchmark, the temperature rise under different redundancy factors was tested, and the results are shown in Table 1 below. Table 1

[0039] It is evident that the temperature rise suppression marginal decreases when it exceeds 6 times, therefore a redundancy range of 6 to 10 times is selected; S452. Record the operating junction temperature of the driving MOSFET Q1 at each multiplier, and calculate the temperature difference between the operating junction temperature and the ambient temperature:

[0040] in, For working temperature, Ambient temperature; S453. Analyze the curve of temperature difference as the multiple increases, identify the inflection point where the rate of temperature difference decreases, and take the multiple corresponding to the inflection point as the multiple of temperature rise suppression inflection point; For example, when the multiplier increases from 4 times to 6 times, the temperature difference decreases from the first threshold (e.g., 6.8℃) to the second threshold (e.g., 1.1℃); when the multiplier continues to increase to more than 6 times, the rate of decrease in temperature difference tends to level off, and the improvement effect diminishes marginally; therefore, 6 times is the inflection point multiplier for suppressing temperature rise. S454. Select the lower limit of the multiple corresponding to the temperature rise suppression inflection point (e.g., 6 times) as the preset multiple; For example, at 6 times the current, the difference between the operating junction temperature of the driving MOSFET Q1 and the ambient temperature is kept within a preset range (e.g., ≤1.1℃). S455. Select the rated current specification of the driving MOSFET Q1 according to the preset multiple: Load current is When selecting a rated current ≥ preset multiple × MOSFET; S5. The reconstructed analog control signal and solenoid valve drive signal are output to the proportional valve and solenoid valve of the external pneumatic circuit component through the signal output module, respectively. The specific steps of step S5 are as follows: S51. The signal output module receives the reconstructed analog signal output by the channel switching unit in step S38, and transmits it to the external high-pressure proportional valve and low-pressure proportional valve through the first analog output port and the second analog output port, respectively. S52. The signal output module receives the solenoid valve drive signal generated in step S43 and transmits it to the external high-pressure solenoid valve and low-pressure solenoid valve through the first switch output port and the second switch output port, respectively. S53. The signal output module is connected to the corresponding interface of the external pneumatic circuit component through four plug-in terminals in a one-time plug-in connection to complete the output of all control signals.

[0041] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pneumatic control board for a low-power laser cutting machine, characterized in that, It includes a power supply input and protection module, a control signal input module, a DC-DC conversion module, an analog signal control module, a solenoid valve drive module, and a signal output module; The input terminal of the power supply input and protection module is connected to an external power source, and the output terminal of the power supply input and protection module is connected to the input terminal of the DC-DC conversion module, the power input terminal of the solenoid valve drive module, and the power supply terminal of the signal output module. The input terminal of the control signal input module is used to receive analog signals within a preset voltage range and switch signals of a first preset voltage value. The output terminal of the control signal input module is connected to the signal input terminal of the analog signal control module. The output of the DC-DC converter module is connected to the power supply of the analog signal control module to provide the analog signal control module with a second preset voltage value. The output terminal of the analog signal control module is connected to the analog signal input terminal of the signal output module; The control signal input terminal of the solenoid valve drive module is used to receive external digital control signals, and the drive output terminal of the solenoid valve drive module is connected to the switch signal input terminal of the signal output module. The interface of the signal output module is used to connect to the high-pressure solenoid valve, low-pressure solenoid valve, high-pressure proportional valve and low-pressure proportional valve of the external pneumatic circuit components. The analog signal control module includes a clamping protection circuit, a first operational amplifier U1A, a linear optocoupler U2, a second operational amplifier U1B, a signal reconstruction and attenuation compensation circuit, and a channel switching unit; The clamping protection circuit includes a resistor R1 and a transient suppression diode D2; The first terminal of resistor R1 is connected to the positive terminal of the analog input, the second terminal of resistor R1 is connected to the first terminal of transient suppression diode D2, the second terminal of transient suppression diode D2 is connected to the negative terminal of the analog input, and grounded; The non-inverting input of the first operational amplifier U1A is connected to the output of the clamping protection circuit. The inverting input of the first operational amplifier U1A is connected to a resistor R5 and is connected to a linear optocoupler U2. The output of the first operational amplifier U1A is connected to a resistor R3. The other end of the resistor R5 is grounded. The linear optocoupler U2 includes an LED, a feedback photodiode PD1, and an output photodiode PD2; The positive terminal of the LED is connected to the other end of the resistor R3, the negative terminal of the LED is grounded, the negative terminal of the output photodiode PD2 is connected to the signal reconstruction and attenuation compensation circuit, and the positive terminal of the output photodiode PD2 is grounded; the negative terminal of the feedback photodiode PD1 is connected to the positive terminal of the second power supply, and the positive terminal of the feedback photodiode PD1 is connected to the inverting input terminal of the first operational amplifier U1A and the resistor R5. The signal reconstruction and attenuation compensation circuit includes a second operational amplifier U1B, a resistor R4, and an adjustable resistor R2. The first terminal of the resistor R4 is connected to the negative terminal of the output photodiode PD2 of the linear optocoupler U2 and the inverting input terminal of the second operational amplifier U1B. The non-inverting input terminal of the second operational amplifier U1B is grounded. The output terminal of the second operational amplifier U1B is connected to the first terminal of the adjustable resistor R2. The second terminal of the adjustable resistor R2 is connected to the second terminal of the resistor R4. The output of the second operational amplifier U1B is also connected to the channel switching unit; The channel switching unit uses a signal relay, which has a common terminal, normally open contact, normally closed contact, first selection terminal and second selection terminal; The first and second selection terminals are used to receive control signals from external digital output ports. The normally open and normally closed contacts are connected to the two analog signal input terminals of the signal output module as the output terminals of the channel switching unit. The working process of the analog signal control module is as follows: S31. After the analog signal is transmitted through a cable with a preset transmission distance, it enters the board. The input voltage is clamped to below the safe threshold by the resistor R1 and transient suppression diode D2 in the clamping protection circuit, and the clamping voltage signal is output. S32. The clamping voltage signal is sent to the non-inverting input of the first operational amplifier U1A. The first operational amplifier U1A drives the LED of the linear optocoupler U2 through resistor R3, so that the LED current is linearly related to the input voltage. S33. The feedback photodiode PD1 of the linear optocoupler U2 receives the optical signal and generates a feedback photocurrent. The feedback photocurrent flows from the inverting input terminal of the first operational amplifier U1A through the feedback photodiode PD1 to ground, and together with the current flowing to ground through resistor R5, satisfies the virtual short balance and establishes linear isolation transmission. S34. The output photodiode PD2 of the linear optocoupler U2 generates a photocurrent proportional to the input side. This photocurrent flows through resistor R4 and generates a voltage at the inverting input terminal of the second operational amplifier U1B. S35. The second operational amplifier U1B, together with resistor R4 and adjustable resistor R2, constitutes a proportional amplifier circuit. The actual gain of the proportional amplifier circuit... Determined by the following formula: S36. Calculate the required target compensation gain based on the measured attenuation data of long-distance transmission. : in, This is the measured voltage after long-distance transmission. The target voltage that needs to be rebuilt; Adjust the resistance value of the adjustable resistor R2 to This makes the actual gain Equal to target compensation gain ; S37. The output terminal of the second operational amplifier U1B outputs the reconstructed analog control signal, which serves as the input signal for the channel switching unit; S38. The channel switching unit receives a time-division control signal from an external digital output port: When the time-sharing control signal is at the first level, the signal relay will connect the reconstructed analog control signal to the first proportional valve interface of the signal output module. When the time-sharing control signal is at the second level, the signal relay will connect the reconstructed analog control signal to the second proportional valve interface; S39. Repeat steps S31 to S38 to realize time-sharing control of the dual proportional valve by a single analog signal based on the periodic change of the time-sharing control signal.

2. The low-power laser cutting machine gas circuit control board according to claim 1, characterized in that, The power input and protection module includes a main input slow-blow fuse F_T1, a first-stage TVS transistor TVS_D1, a reverse connection protection MOSFET Q2, a second-stage TVS transistor TVS_D2, three branch protection circuits, and three LED status indicator circuits. The first terminal of the main input slow-blow fuse F_T1 is connected to the positive terminal of the external power supply, and the second terminal is connected to the first terminal of the first-stage TVS transistor TVS_D1, serving as the primary power supply output terminal; the second terminal of the first-stage TVS transistor TVS_D1 is connected to the ground of the external power supply. The reverse polarity protection MOSFET Q2 is an N-channel MOSFET with its drain connected to the external power supply ground, its source connected to the board system ground, and its gate connected to the primary power supply output terminal through a voltage divider resistor network. The primary power supply output terminal is connected to the protection circuits of all three branch circuits; The three branch protection circuits are the first branch, the second branch, and the third branch, respectively; The first branch is equipped with a medium-speed fuse F_MD2. The first end of the medium-speed fuse F_MD2 is connected to the one-time power supply output terminal, and the second end is connected to the proportional valve branch power supply terminal. The second branch is equipped with a medium-speed fuse F_MD3. The first end of the medium-speed fuse F_MD3 is connected to the one-time power supply output terminal, and the second end is connected to the power supply terminal of the solenoid valve branch. The third branch is equipped with a self-resetting fuse F_PTC4. The first end of the self-resetting fuse F_PTC4 is connected to the one-time power supply output terminal, and the second end is connected to the power supply terminal of the control circuit branch. The second-stage TVS transistor, TVS_D2, is connected in parallel between the power supply terminal of the control circuit branch and the system ground of the board. The three LED status indicator circuits are respectively connected between the power supply terminals of the proportional valve branch, the solenoid valve branch, and the control circuit branch, and the system ground of the board.

3. The low-power laser cutting machine gas circuit control board according to claim 2, characterized in that, The solenoid valve drive module includes an optocoupler U3, a drive MOSFET Q1, and a freewheeling diode D3; The input side of optocoupler U3 is used to receive external digital control signals; The gate of the driving MOSFET Q1 is connected to resistors R7 and R8, and the other end of resistor R7 is connected to the output side of optocoupler U3. The source of the driving MOSFET Q1 is connected to the other end of the resistor R8 and grounded, and the drain of the driving MOSFET Q1 is connected to the negative terminal of the external solenoid valve. The positive terminal of the freewheeling diode D3 is connected to the drain of the driving MOSFET Q1, and the negative terminal of the freewheeling diode D3 is connected to the positive power supply terminal of the external solenoid valve. The ratio of the rated current of the driving MOSFET Q1 to the rated current of the driven solenoid valve is greater than or equal to 6.

4. The low-power laser cutting machine gas circuit control board according to claim 2, characterized in that, The control signal input module uses waterproof terminals and sets the port spacing between analog signals and digital signals to a preset terminal spacing. The signal output module includes four plug terminals, which are used to connect to the high-pressure solenoid valve, low-pressure solenoid valve, high-pressure proportional valve and low-pressure proportional valve of the external pneumatic circuit components, respectively.

5. A control method based on the gas circuit control board of a low-power laser cutting machine according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1. The power input and protection module provides graded protection and conversion of the input power supply to provide power supply voltage to each module; S2. Receive external analog signals and digital signals through the control signal input module; S3. The analog signal control module performs clamping protection, isolation transmission, attenuation compensation reconstruction, and channel switching on the received analog signal to generate the reconstructed analog control signal. S4. Receive external digital control signals through the solenoid valve drive module, and generate solenoid valve drive signals to drive the solenoid valve on and off after isolation; S5. The reconstructed analog control signal and solenoid valve drive signal are output to the proportional valve and solenoid valve of the external pneumatic circuit component through the signal output module.

6. The control method according to claim 5, characterized in that, The specific steps of step S1 are as follows: S11. After the positive terminal of the external power supply passes through the main input slow-blow fuse F_T1, the first-stage TVS tube TVS_D1 clamps the input surge voltage, generating a primary power supply output. S12. The reverse connection protection MOSFET Q2 automatically turns on according to the primary power supply output, connecting the external power ground to the board system ground to achieve reverse connection protection; S13. The primary power supply is output into three paths: the first path is output to the proportional valve branch power supply terminal via the medium-speed fuse F_MD2; the second path is output to the solenoid valve branch power supply terminal via the medium-speed fuse F_MD3; and the third path is output to the control circuit branch power supply terminal via the self-resetting fuse F_PTC4. S14. The second-stage TVS transistor TVS_D2 performs secondary overvoltage clamping on the power supply terminal of the control circuit branch to suppress the induced voltage surge generated by the operation of the solenoid valve. S15. Determine whether the power supply of the corresponding branch is normal by checking the on / off status of the three LED status indicator circuits.

7. The control method according to claim 6, characterized in that, The specific steps of step S4 are as follows: S41. The solenoid valve drive module receives the control signal from the external digital output port and uses the signal to drive the input-side light-emitting diode of the optocoupler U3; S42. The phototransistor on the output side of optocoupler U3 is turned on, and the isolated drive level is applied to the gate of drive MOS transistor Q1 through resistor R7 to determine the drive level. When the drive level is high, proceed to step S43; When the drive level is low, proceed to step S44; S43. Drive MOSFET Q1 to conduct, its drain is pulled to ground, the negative terminal of the external solenoid valve is energized, the solenoid valve is activated, and proceed to step S45. S44. When the drive MOSFET Q1 is turned off, the external solenoid valve is de-energized and reset. The reverse electromotive force generated by the coil of the external solenoid valve forms a freewheeling circuit through the freewheeling diode D3, clamping the spike voltage at the supply voltage and protecting the drive MOSFET Q1. S45. Set the rated current of the driving MOSFET Q1 to a preset multiple or more than the rated current of the driven solenoid valve. By using the redundancy of the rated current of the driving MOSFET Q1 exceeding the actual load current, the operating junction temperature of the driving MOSFET Q1 under the preset high temperature ambient temperature and without forced heat dissipation is suppressed. The specific steps of step S5 are as follows: S51. The signal output module receives the reconstructed analog signal output by the channel switching unit in step S38, and transmits it to the external high-pressure proportional valve and low-pressure proportional valve through the first analog output port and the second analog output port, respectively. S52. The signal output module receives the solenoid valve drive signal generated in step S43 and transmits it to the external high-pressure solenoid valve and low-pressure solenoid valve through the first switch output port and the second switch output port, respectively. S53. The signal output module is connected to the corresponding interface of the external pneumatic circuit component through four plug-in terminals in a one-time plug-in connection to complete the output of all control signals.

8. The control method according to claim 7, characterized in that, The process of determining the preset multiple in step S45 is as follows: S451. Based on the rated current of the solenoid valve, select several samples with different current multiples and conduct continuous working temperature rise tests under preset high temperature environment and natural heat dissipation conditions. S452. Record the operating junction temperature of the driving MOSFET Q1 at each multiplier, and calculate the temperature difference between the operating junction temperature and the ambient temperature: in, For working temperature, Ambient temperature; S453. Analyze the curve of temperature difference as the multiple increases, identify the inflection point where the rate of temperature difference decreases, and take the multiple corresponding to the inflection point as the multiple of temperature rise suppression inflection point; S454. Select the lower limit of the multiple corresponding to the temperature rise suppression inflection point as the preset multiple; S455. Select the rated current specification of the driving MOSFET Q1 according to the preset multiple: Load current is When selecting a rated current ≥ preset multiple × MOSFET.

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