Purity control method and system for laser cutting mixed gas

Abstract

The invention relates to the technical field of laser cutting mixed gas output control, in particular to a laser cutting mixed gas purity control method and system.The method comprises the steps that after a control device receives a starting instruction input by a user, initialization setting is carried out according to values of interface parameters, and the starting instruction is started; meanwhile, detection data transmitted by the mixed gas analyzer in real time are received; the control device performs logical operation according to detection data transmitted by the mixed gas analyzer in real time and a preset logic rule, calculates a control quantity based on a preset PID control algorithm, generates a corresponding control instruction according to a logical operation result and the control quantity, and transmits the control instruction to the valve body control unit; the valve body control unit is used for controlling a gas outlet valve, a waste gas discharge valve and adsorption time of the high-pressure module nitrogen making device according to the control instruction so as to adjust the nitrogen concentration. And stable purity of the output mixed gas is ensured, so that the laser cutting quality and speed are improved.

Description

Technical Field

[0001] The present application relates to the technical field of laser cutting gas mixture output control, and in particular to a laser cutting mixed gas purity control method and system. Background Art

[0002] In the field of laser cutting, auxiliary gases play an indispensable role in ensuring the smooth progress of the cutting process and the quality of cutting. Currently, the auxiliary gases widely used in the market are mostly oxygen, nitrogen, or a mixture of the two. Compared with pure nitrogen and pure oxygen, mixed gases exhibit unique advantages in the cutting process and can better meet the needs of different cutting processes. However, the cutting process has strict requirements on the relative content of nitrogen and oxygen in the mixed gas, and its selection requires comprehensive consideration of multiple factors, among which the material and thickness of the cutting plate are key influencing factors. Taking stainless steel cutting as an example, the use of a mixed gas with a high nitrogen content for cutting can effectively suppress the oxidation reaction and more efficiently blow away the molten material, thereby achieving better cutting results. For plates of other materials such as carbon steel, the required nitrogen content of the mixed gas is different.

[0003] If the purity of the mixed gas is not properly selected, problems such as severe plate cutting slag and uneven cross-sections are likely to occur during the cutting process, greatly reducing the cutting quality. This will also affect the cutting speed and increase production costs. On the other hand, the existing mixed gas preparation process is greatly affected by the gas consumption of the laser cutting machine terminal, resulting in unstable purity of the output mixed gas. In actual production, the gas consumption of the laser cutting machine will frequently change with the different cutting tasks, making it difficult for existing mixed gas preparation equipment to stably provide the required mixed gas, and unable to meet the needs of high-precision, high-quality laser cutting. Summary of the Invention

[0004] In view of the fact that existing mixed gas preparation equipment is difficult to stably provide mixed gases that meet the requirements and cannot meet the needs of high-precision and high-quality laser cutting, the present invention provides a method and system for controlling the purity of mixed gases in laser cutting.

[0005] In a first aspect, the technical solution of the present invention provides a method for controlling the purity of mixed gas in laser cutting, comprising the following steps: S1: The control device receives interface parameters input by the user; S2: After receiving the start-up command input by the user, the control device performs initialization settings according to the values of the interface parameters and simultaneously receives the detection data transmitted in real time by the mixed gas analyzer; S3: The control device performs logical operations according to the detection data transmitted in real time by the mixed gas analyzer according to the preset logical rules, and calculates the control quantity based on the preset PID control algorithm. According to the logical operation results and the control quantity, the control device generates corresponding control instructions and transmits them to the valve body control unit; S4: The valve body control unit controls the outlet valve, the exhaust gas discharge valve and the adsorption time of the high-pressure module nitrogen generator according to the control instruction to adjust the nitrogen concentration; S5: Determine whether the nitrogen concentration reaches the set concentration value; If yes, maintain the current control state; If not, go to step S3.

[0006] As a preferred embodiment of the technical solution of the present invention, the nitrogen purity is A, the control accuracy is ±K, and the logic rules in step S3 include: The first level of logic rules: judge whether the gas concentration meets the set concentration range. When the detection value AK≤X≤A+K, the gas concentration meets the set concentration range; The second logical rule: judge whether the gas concentration is lower than the set concentration range. When the detection value X<AK, the gas concentration is lower than the set concentration range; The third level logic rule: determine whether the time when the equipment is started or the last time the nitrogen purity is switched exceeds the system preset value.

[0007] As a preferred embodiment of the technical solution of the present invention, the method includes: When the logic operation of the first-level logic rule passes, the valve control unit opens the outlet valve of the high-pressure module nitrogen generator according to the received control instruction and starts normal gas supply; the valve control unit continues to operate according to this control instruction until the logic operation of the first-level logic rule fails and enters the logic operation of the second-level logic rule; When the logic operation of the second-level logic rule passes, the valve body control unit opens the exhaust valve of the equipment according to the received control instruction, starts to empty the unqualified gas in the mixed gas process tank, and performs the logic operation of the third-level logic rule at the same time; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously increase the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, so as to reduce the nitrogen concentration until the adsorption time reaches the first set value.

[0008] As a preferred embodiment of the technical solution of the present invention, the method further comprises: When the logic operation of the second-level logic rule fails, the valve body control unit opens the valve leading to the gas mixing process tank according to the received control instruction, reducing the nitrogen purity of the gas mixing process tank, and at the same time the control device performs the logic operation of the third-level logic rule; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously reduce the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, thereby increasing the nitrogen concentration until the adsorption time reaches the second set value.

[0009] As a preferred embodiment of the technical solution of the present invention, the method further comprises: The control module converts the analog quantity into a digital quantity for calculation, and controls the nitrogen concentration output by the high-pressure module nitrogen generator in combination with the nitrogen concentration, compressed gas pressure, adsorption time, pressure equalization time, and nitrogen purity alarm value set in the interface, and uses a pre-built PID control algorithm to control the nitrogen concentration value.

[0010] As a preferred embodiment of the technical solution of the present invention, the method further comprises: The control device analyzes the current nitrogen concentration value and the input value on the interface, and calculates the nitrogen concentration compensation value through the PID algorithm model; the nitrogen concentration compensation value is sent to the valve body control unit to control the on and off of nitrogen, which is used to adjust the nitrogen concentration in the tank; data acquisition, PID control algorithm calculation and nitrogen concentration control are continuously performed until the nitrogen production concentration is stabilized within the preset value range.

[0011] As a preferred embodiment of the technical solution of the present invention, the method further comprises: When the nitrogen concentration exceeds the preset value, the control device uses the PID control algorithm to reduce the proportional coefficient to reduce the nitrogen concentration until the actual nitrogen value is within the preset value range; When the nitrogen concentration is lower than the preset value, the control device uses the PID control algorithm to increase the proportional coefficient to increase the nitrogen concentration until the actual nitrogen value is within the preset value range.

[0012] The present invention reduces the number of times users have to manually adjust parameters by integrating automated logic rules and PID control algorithms into the control device. Users only need to set the relevant parameters when using for the first time, and subsequent operations do not require frequent adjustments, making it more convenient to use. The PID control algorithm flexibly adjusts different flow and pressure values, avoiding the phenomenon of fluctuating nitrogen concentrations caused by excessive or insufficient gas consumption, further improving processing stability. By real-time monitoring of nitrogen concentration changes and combining real-time compensation with the PID control algorithm, it is ensured that the nitrogen concentration can remain stable when the gas end continues to discharge gas, avoiding a decrease in cutting quality due to fluctuations in gas consumption.

[0013] As a preferred embodiment of the technical solution of the present invention, the method further comprises: The control device determines the compensation interval of the nitrogen concentration and judges whether the nitrogen concentration is within the preset value range. If not, it generates a nitrogen concentration change curve graph of the equipment to be cut during the nitrogen use time period, and generates a nitrogen concentration horizontal line on the nitrogen concentration change curve graph according to the compensation interval, and calculates the area of several closed images enclosed by the nitrogen concentration change curve graph and the horizontal line.

[0014] As a preferred embodiment of the technical solution of the present invention, the method further comprises: When the cutting equipment starts to use nitrogen, the control device starts to record the nitrogen concentration data corresponding to each time point. When it is determined that the nitrogen concentration is not within the preset value range, a nitrogen concentration change curve is generated according to the recorded time and nitrogen concentration data; Generate a nitrogen concentration horizontal line on the nitrogen concentration change curve graph, the ordinate value of the horizontal line is a preset nitrogen concentration value, that is, the middle value of the nitrogen concentration compensation interval; Discretize the nitrogen concentration change curve and the nitrogen concentration horizontal line into a series of data points; The area between two adjacent data points is regarded as a trapezoid, the area of each trapezoid is calculated, and then the areas of all trapezoids are added together to obtain the total area of the closed image.

[0015] In a second aspect, the technical solution of the present invention further provides a laser cutting mixed gas purity control system, comprising a parameter input unit, a control device, a mixed gas analyzer, a high-pressure module nitrogen generator and a valve body control unit; The user inputs interface parameters and startup instructions through the parameter input unit; Mixed gas analyzer, used to detect the purity of nitrogen in the pipeline; The control device is configured to receive input interface parameter values, including nitrogen purity, input gas pressure, input gas flow rate, output gas flow rate, output gas pressure, control accuracy, adsorption time, and AB tower switching time; upon receiving a startup instruction input by a user, perform initialization settings according to the interface parameter values, and simultaneously receive detection data transmitted in real time from a mixed gas analyzer; the control device performs logical operations according to pre-set logical rules based on the detection data transmitted in real time from the mixed gas analyzer, and simultaneously calculates a control quantity based on a preset PID control algorithm; generates corresponding control instructions based on the logical operation results and the control quantity, and transmits the instructions to the valve body control unit; The valve body control unit is used to control the outlet valve, exhaust gas discharge valve and adsorption time of the high-pressure module nitrogen making device according to the control instructions to adjust the nitrogen concentration.

[0016] As a preferred embodiment of the technical solution of the present invention, the nitrogen purity is A, the control accuracy is ±K, and the logic rules include: The first level of logic rules: judge whether the gas concentration meets the set concentration range. When the detection value AK≤X≤A+K, the gas concentration meets the set concentration range; The second logical rule: judge whether the gas concentration is lower than the set concentration range. When the detection value X<AK, the gas concentration is lower than the set concentration range; The third level logic rule: determine whether the time when the equipment is started or the last time the nitrogen purity is switched exceeds the system preset value.

[0017] As a preferred embodiment of the technical solution of the present invention, when the logical operation of the first-level logic rule passes, the valve body control unit opens the gas outlet valve of the high-pressure module nitrogen generator according to the received control instruction and starts normal gas supply; the valve body control unit continues to operate according to this control instruction until the logical operation of the first-level logic rule fails and enters the logical operation of the second-level logic rule; When the logic operation of the second-level logic rule passes, the valve body control unit opens the exhaust valve of the equipment according to the received control instruction, starts to empty the unqualified gas in the mixed gas process tank, and performs the logic operation of the third-level logic rule at the same time; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously increase the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, so as to reduce the nitrogen concentration until the adsorption time reaches the first set value.

[0018] As a preferred embodiment of the technical solution of the present invention, when the logic operation of the second-level logic rule fails, the valve body control unit opens the valve leading to the gas mixing process tank according to the received control instruction, thereby reducing the nitrogen purity of the gas mixing process tank, and at the same time, the control device performs the logic operation of the third-level logic rule; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously reduce the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, thereby increasing the nitrogen concentration until the adsorption time reaches the second set value.

[0019] As a preferred embodiment of the technical solution of the present invention, the control module converts the analog quantity into a digital quantity for calculation, and controls the nitrogen concentration output by the high-pressure module nitrogen generator in combination with the nitrogen concentration, compressed gas pressure, adsorption time, pressure equalization time, and nitrogen purity alarm value set in the interface, and uses a pre-built PID control algorithm to control the nitrogen concentration value.

[0020] As a preferred embodiment of the technical solution of the present invention, the control device analyzes the current nitrogen concentration value and the input value on the interface, and calculates the nitrogen concentration compensation value through the PID algorithm model; the nitrogen concentration compensation value is sent to the valve body control unit to control the on and off of nitrogen, so as to adjust the nitrogen concentration in the tank body; data acquisition, PID control algorithm calculation and nitrogen concentration control are continuously performed until the nitrogen production concentration is stabilized within the preset value range.

[0021] As a preferred embodiment of the technical solution of the present invention, when the nitrogen concentration exceeds a preset value, the control device uses a PID control algorithm to reduce the proportional coefficient to reduce the nitrogen concentration until the actual nitrogen value is within the preset value range; When the nitrogen concentration is lower than the preset value, the control device uses the PID control algorithm to increase the proportional coefficient to increase the nitrogen concentration until the actual nitrogen value is within the preset value range.

[0022] As a preferred embodiment of the technical solution of the present invention, the control device determines the compensation interval of the nitrogen concentration and judges whether the nitrogen concentration is within the preset value range. If not, a nitrogen concentration change curve graph of the equipment to be cut during the nitrogen use time period is generated, and a nitrogen concentration horizontal line is generated on the nitrogen concentration change curve graph according to the compensation interval, and the area of several closed images enclosed by the nitrogen concentration change curve graph and the horizontal line is calculated.

[0023] As a preferred embodiment of the technical solution of the present invention, when the cutting equipment starts to use nitrogen, the control device starts to record the nitrogen concentration data corresponding to each time point. When it is determined that the nitrogen concentration is not within the preset value range, a nitrogen concentration change curve is generated according to the recorded time and nitrogen concentration data; Generate a nitrogen concentration horizontal line on the nitrogen concentration change curve graph, the ordinate value of the horizontal line is a preset nitrogen concentration value, that is, the middle value of the nitrogen concentration compensation interval; Discretize the nitrogen concentration change curve and the nitrogen concentration horizontal line into a series of data points; The area between two adjacent data points is regarded as a trapezoid, the area of each trapezoid is calculated, and then the areas of all trapezoids are added together to obtain the total area of the closed image.

[0024] As can be seen from the above technical solution, this application has the following advantages: through real-time monitoring and feedback from the control device and mixed gas analyzer, combined with multi-layer logic rules and PID control algorithms, the nitrogen content in the mixed gas can be precisely adjusted to ensure the stable purity of the output mixed gas, thereby improving the quality and speed of laser cutting. This can avoid the situation where the difference in mixed gas purity required for plates of different thicknesses and materials causes a decrease in cutting quality and speed, effectively reduce the phenomenon of dross when cutting carbon steel plates, and improve the cutting effect and stability of laser cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 A schematic flow chart of a method provided in an embodiment of the present invention.

[0027] Figure 2 This is the adjustment logic of the system provided by the embodiment of the present invention during the laser cutting process. DETAILED DESCRIPTION

[0028] In order to make the application objectives, features, and advantages of this application more obvious and easy to understand, the technical solutions protected by this application will be clearly and completely described below using specific embodiments and drawings. Obviously, the embodiments described below are only part of the embodiments of this application, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this patent.

[0029] like Figure 1 As shown, an embodiment of the present invention provides a method for controlling the purity of mixed gas in laser cutting, comprising the following steps: S1: The control device receives interface parameters input by the user; the interface parameters include nitrogen purity, input gas pressure, input gas flow, output gas flow, output gas pressure, control accuracy, adsorption time, and AB tower switching time; S2: After receiving the start-up command input by the user, the control device performs initialization settings according to the values of the interface parameters and simultaneously receives the detection data transmitted in real time by the mixed gas analyzer; Initialize the operating status of the high-pressure module nitrogen generator based on the set parameters such as nitrogen purity, adsorption time, and AB tower switching time. Ensure that the high-pressure module nitrogen generator can switch at the set time interval.

[0030] Initialize the status of each valve (such as closing the air inlet, air outlet, exhaust valve, etc.) to ensure that the system is in a safe state when starting.

[0031] Start the mixed gas analyzer and ensure that it can normally detect gas concentration, flow, pressure and other data.

[0032] It should be noted that the test data usually includes: nitrogen concentration (the percentage of nitrogen in the mixed gas), oxygen concentration (the percentage of oxygen in the mixed gas), gas flow, i.e. the flow value of the mixed gas, and gas pressure, i.e. the pressure value of the mixed gas.

[0033] S3: The control device performs logical operations according to the detection data transmitted in real time by the mixed gas analyzer according to the preset logical rules, and calculates the control quantity based on the preset PID control algorithm. According to the logical operation results and the control quantity, the control device generates corresponding control instructions and transmits them to the valve body control unit; In the embodiment of the present invention, the nitrogen purity is A, the control accuracy is ±K, and the logic rules include: The first level of logic rules: judge whether the gas concentration meets the set concentration range. When the detection value AK≤X≤A+K, the gas concentration meets the set concentration range; The second logical rule: judge whether the gas concentration is lower than the set concentration range. When the detection value X<AK, the gas concentration is lower than the set concentration range; The third level logic rule: determine whether the time when the equipment is started or the last time the nitrogen purity is switched exceeds the system preset value.

[0034] The logical operation process includes: When the detection value AK≤X≤A+K received by the control device, the gas concentration meets the set concentration range and the first-level logical operation is passed.

[0035] When the control device receives the detection value X<AK fed back by the mixed gas analyzer, the gas concentration is lower than the set concentration range, and the second-level logical operation is passed.

[0036] When the equipment is powered on or the time since the last nitrogen purity switch exceeds the system preset value, the third-level logic operation passes.

[0037] S4: The valve body control unit controls the outlet valve, the exhaust gas discharge valve and the adsorption time of the high-pressure module nitrogen generator according to the control instruction to adjust the nitrogen concentration; S5: Determine whether the nitrogen concentration reaches the set concentration value; If yes, maintain the current control state; If not, go to step S3.

[0038] In some embodiments, step S3 includes: The control module converts analog quantities into digital quantities for calculation. Combined with the nitrogen concentration, compressed gas pressure, adsorption time, pressure equalization time, and nitrogen purity alarm value set on the interface, it uses the pre-built PID control algorithm to calculate the control quantity and generate control instructions to the valve body control unit.

[0039] Specifically, the control device analyzes the current nitrogen concentration value and the input value on the interface, and calculates the nitrogen concentration compensation value through the PID algorithm model; the nitrogen concentration compensation value is sent to the valve body control unit to control the nitrogen on and off, thereby adjusting the nitrogen concentration in the tank; data acquisition, PID control algorithm calculation and nitrogen concentration control are continuously performed until the nitrogen production concentration is stabilized within the preset value range; When the nitrogen concentration exceeds a preset value, the control device uses a PID control algorithm to reduce the proportional coefficient to reduce the nitrogen concentration until the actual nitrogen value is within the preset value range; When the nitrogen concentration is lower than the preset value, the control device uses the PID control algorithm to increase the proportional coefficient to increase the nitrogen concentration until the actual nitrogen value is within the preset value range.

[0040] The present invention reduces the number of times users have to manually adjust parameters by integrating automated logic rules and PID control algorithms into the control device. Users only need to set the relevant parameters when using for the first time, and subsequent operations do not require frequent adjustments, making it more convenient to use. The PID control algorithm flexibly adjusts different flow and pressure values, avoiding the phenomenon of fluctuating nitrogen concentrations caused by excessive or insufficient gas consumption, further improving processing stability. By real-time monitoring of nitrogen concentration changes and combining real-time compensation with the PID control algorithm, it is ensured that the nitrogen concentration can remain stable when the gas end continues to discharge gas, avoiding a decrease in cutting quality due to fluctuations in gas consumption.

[0041] The PID control algorithm calculates the nitrogen concentration compensation value through the following steps: The control module converts the analog signals (such as nitrogen concentration, gas pressure, etc.) detected by the mixed gas analyzer into digital signals through an analog-to-digital converter (ADC); Input analog quantities: nitrogen concentration X, compressed gas pressure P, adsorption time Tads, and pressure equalization time Teq.

[0042] Output digital quantity: discrete numerical value Xd, Pd, Tads_d, Teq_d.

[0043] The PID control algorithm first calculates the deviation (error) between the current nitrogen concentration value and the set value. The deviation calculation formula is: e ( t ) = set value − actual nitrogen concentration in, e ( t ) is the deviation at the current moment; the set value is the nitrogen concentration target value entered by the user through the interface; the actual nitrogen concentration value is the nitrogen concentration detected in real time by the mixed gas analyzer; The proportional term generates the control amount in proportion to the current deviation. The calculation formula of the proportional term is:

[0044] in, is the proportional coefficient, which is set by the user or automatically adjusted by the system; is the control quantity of the proportional term.

[0045] The integral term generates a control quantity based on the accumulated value of the deviation, which is used to eliminate the steady-state error of the system. The calculation formula of the integral term is:

[0046] in, is the integral coefficient, which is set by the user or automatically adjusted by the system; is the control quantity of the integral term; Indicates the cumulative deviation value from system startup to the current moment; The differential term generates a control variable based on the rate of change of the deviation, which is used to suppress overshoot and oscillation of the system. The calculation formula of the differential term is:

[0047] in, is the differential coefficient, which is set by the user or automatically adjusted by the system; is the control quantity of the differential term; Indicates the rate of change of the deviation.

[0048] Add the proportional term, integral term, and differential term to get the PID control value (i.e., nitrogen concentration compensation value). The calculation formula for the PID control value is:

[0049] in, It is the PID control quantity, that is, the nitrogen concentration compensation value.

[0050] In digital systems, the PID control algorithm is usually implemented in discrete form:

[0051] in, is the control quantity at the kth sampling moment; is the deviation at the kth sampling moment; is the sampling time interval.

[0052] The calculation continues based on the interface parameters. Input parameters include the nitrogen concentration setpoint A (from the user interface), control accuracy ±K (allowable fluctuation range), compressed gas pressure P, adsorption time Tads, pressure equalization time Teq, and nitrogen purity alarm value.

[0053] According to the relationship between the detection value X and the set value A, adjust the PID parameters: If AK≤X≤A+K, maintain the current PID parameters; If X<AK, increase or To increase nitrogen concentration; If X>A+K, reduce or increase To reduce nitrogen concentration.

[0054] PID control algorithm calculated Converted into instructions executable by the valve control unit: like >0, increase the opening of the outlet valve or extend the adsorption time; like <0, open the exhaust valve or shorten the adsorption time.

[0055] The digital control quantity is converted to Converted into analog signal to drive the valve actuator.

[0056] For example, if the nitrogen concentration compensation value is positive, it means that the nitrogen concentration needs to be increased, and the on-off valve will open to increase the nitrogen flow rate; if the nitrogen concentration compensation value is negative, it means that the nitrogen concentration needs to be reduced, and the on-off valve will close to reduce the nitrogen flow rate.

[0057] During PID control calculations, the PID control algorithm automatically adjusts the proportional, integral, and differential parameters based on the calculated deviation. The proportional component is used to quickly respond to deviations, the integral component is used to eliminate the system's steady-state errors, and the differential component is used to predict the changing trend of the deviation and make adjustments in advance. The adjusted parameters are substituted into the PID calculation formula to calculate the current control variable. This control variable is used to adjust the operating parameters of the high-pressure module nitrogen generator, such as adsorption time and pressure equalization time, to achieve precise control of nitrogen concentration.

[0058] Based on the control variable calculated by the PID algorithm, corresponding control instructions are sent to the high-pressure module nitrogen generator to adjust its operating parameters. For example, if the current nitrogen concentration is lower than the set value, the control module will increase the adsorption time or adjust the pressure equalization time to increase the nitrogen output concentration; conversely, if the nitrogen concentration is higher than the set value, the adsorption time will be reduced or adjusted accordingly.

[0059] During the regulation process, the control device continuously monitors changes in nitrogen concentration and processes and analyzes the newly acquired data. Based on the new deviation, the PID algorithm continuously adjusts the control variable, forming a closed-loop feedback control system to ensure that the nitrogen concentration remains stable near the set value.

[0060] In some embodiments, step S4 specifically includes: When the logic operation of the first-level logic rule passes, the valve control unit opens the outlet valve of the high-pressure module nitrogen generator according to the received control instruction and starts normal gas supply; the valve control unit continues to operate according to this control instruction until the logic operation of the first-level logic rule fails and enters the logic operation of the second-level logic rule; When the logic operation of the second-level logic rule passes, the valve body control unit opens the exhaust valve of the equipment according to the received control instruction, starts to empty the unqualified gas in the mixed gas process tank, and performs the logic operation of the third-level logic rule at the same time; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously increase the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, so as to reduce the nitrogen concentration until the adsorption time reaches the first set value.

[0061] When the logic operation of the second-level logic rule fails, the valve body control unit opens the valve leading to the gas mixing process tank according to the received control instruction, reducing the nitrogen purity of the gas mixing process tank, and at the same time the control device performs the logic operation of the third-level logic rule; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously reduce the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, thereby increasing the nitrogen concentration until the adsorption time reaches the second set value.

[0062] In some embodiments, the method further comprises: S6: Determine whether the nitrogen concentration is within a preset value range. If not, generate a nitrogen concentration change curve for the equipment to be cut during the nitrogen use time period, and generate a nitrogen concentration horizontal line on the nitrogen concentration change curve according to the compensation interval, and calculate the area of several closed images enclosed by the nitrogen concentration change curve and the horizontal line.

[0063] Step S6 specifically includes: when the cutting equipment starts to use nitrogen, the control device starts to record the nitrogen concentration data corresponding to each time point, and when it is determined that the nitrogen concentration is not within the preset value range, generates a nitrogen concentration change curve according to the recorded time and nitrogen concentration data; Generate a nitrogen concentration horizontal line on the nitrogen concentration change curve graph, the ordinate value of the horizontal line is a preset nitrogen concentration value, that is, the middle value of the nitrogen concentration compensation interval; Discretize the nitrogen concentration change curve and the nitrogen concentration horizontal line into a series of data points; The area between two adjacent data points is regarded as a trapezoid, the area of each trapezoid is calculated, and then the areas of all trapezoids are added together to obtain the total area of the closed image.

[0064] The control device determines whether the nitrogen concentration is within the preset range, providing an intuitive indication of whether the nitrogen concentration meets cutting requirements. If it is outside the preset range, a nitrogen concentration curve and a nitrogen concentration horizontal line are generated. The area of the closed image formed by these two curves is calculated to quantify the degree of deviation of the nitrogen concentration from the preset value. The larger the area, the more severe the deviation of the nitrogen concentration from the preset value during that period, providing a precise basis for subsequent adjustments. For example, when cutting stainless steel sheets, if the preset nitrogen concentration is 90%, and the concentration fluctuates significantly during the actual cutting process, calculating the area can clearly understand the overall concentration deviation.

[0065] The calculated area can be used to optimize the pre-built PID control algorithm. Based on the concentration deviation indicated by the area, the proportional, integral, and differential coefficients in the PID algorithm are adjusted. If the area indicates a persistently large concentration deviation, the integral coefficient can be increased appropriately to enhance the cumulative regulation of the deviation. If the area indicates drastic concentration fluctuations, the differential coefficient can be increased to make the system respond more quickly to concentration changes, thereby more accurately adjusting the nitrogen concentration compensation value and stabilizing the purity of the mixed gas.

[0066] By observing the nitrogen concentration change curve and calculating the area, we can analyze the stability of the mixed gas supply during the laser cutting process. If the area fluctuates greatly, it means that the nitrogen concentration is unstable, which may affect the cutting quality and cause problems such as rough cut surfaces and slag. By recording and analyzing these data over a long period of time, potential faults in the nitrogen generation device or gas mixing system can be discovered in a timely manner, and the equipment can be maintained in advance to ensure the smooth progress of the cutting work. It is convenient to correlate the calculated area data with the cutting quality data in the later stage, which can provide a strong basis for improving the laser cutting process. If it is found that under a specific cutting process, the area enclosed by the nitrogen concentration change curve and the horizontal line is always large, and the cutting quality is poor, the cutting parameters can be adjusted in a targeted manner, such as changing the cutting speed and power, or optimizing the ratio of the mixed gas, to improve the cutting effect and production efficiency.

[0067] In some embodiments, the control device compares the current nitrogen concentration with a nitrogen purity alarm value in real time. If the nitrogen concentration exceeds the alarm value range, the control device triggers an alarm mechanism, emits an audible and visual alarm signal, and takes appropriate safety measures, such as stopping the nitrogen generator or adjusting process parameters, to ensure safe operation of the system.

[0068] The embodiment of the present invention further provides a laser cutting mixed gas purity control system, comprising a parameter input unit, a control device, a mixed gas analyzer, a high-pressure module nitrogen generator and a valve body control unit; The user inputs interface parameters and startup instructions through the parameter input unit; Mixed gas analyzer, used to detect the purity of nitrogen in the pipeline; The control device is configured to receive input interface parameter values, including nitrogen purity, input gas pressure, input gas flow, output gas flow, output gas pressure, control accuracy, adsorption time, and AB tower switching time; upon receiving a start-up instruction input by a user, perform initialization settings according to the interface parameter values, and simultaneously receive detection data transmitted in real time by a mixed gas analyzer; perform logical operations according to pre-set logical rules based on the detection data transmitted in real time by the mixed gas analyzer; generate corresponding control instructions based on the results of the logical operations, and transmit them to the valve body control unit; The valve body control unit is used to control the outlet valve, exhaust gas discharge valve and adsorption time of the high-pressure module nitrogen making device according to the control instructions. At the same time, the control device controls and adjusts the concentration of nitrogen in the tank based on a preset PID control algorithm.

[0069] In the embodiment of the present invention, the nitrogen purity is A, the control accuracy is ±K, and the logic rules include: The first level of logic rules: judge whether the gas concentration meets the set concentration range. When the detection value AK≤X≤A+K, the gas concentration meets the set concentration range; The second logical rule: judge whether the gas concentration is lower than the set concentration range. When the detection value X<AK, the gas concentration is lower than the set concentration range; The third level logic rule: determine whether the time when the equipment is started or the last time the nitrogen purity is switched exceeds the system preset value.

[0070] Accordingly, when the logic operation of the first-level logic rule passes, the valve control unit opens the outlet valve of the high-pressure module nitrogen generator according to the received control instruction and starts normal gas supply; the valve control unit continues to operate according to this control instruction until the logic operation of the first-level logic rule fails and enters the logic operation of the second-level logic rule; When the logic operation of the second-level logic rule passes, the valve body control unit opens the exhaust valve of the equipment according to the received control instruction, starts to empty the unqualified gas in the mixed gas process tank, and performs the logic operation of the third-level logic rule at the same time; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously increase the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, so as to reduce the nitrogen concentration until the adsorption time reaches the first set value.

[0071] When the logic operation of the second-level logic rule fails, the valve body control unit opens the valve leading to the gas mixing process tank according to the received control instruction, reducing the nitrogen purity of the gas mixing process tank, and at the same time the control device performs the logic operation of the third-level logic rule; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously reduce the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, thereby increasing the nitrogen concentration until the adsorption time reaches the second set value.

[0072] In some embodiments, the control module converts analog quantities into digital quantities for calculation, and controls the nitrogen concentration output by the high-pressure module nitrogen generator in combination with the nitrogen concentration, compressed gas pressure, adsorption time, pressure equalization time, and nitrogen purity alarm value set in the interface, and uses a pre-built PID control algorithm to control the nitrogen concentration value.

[0073] The control device analyzes the current nitrogen concentration value and the input value on the interface, and calculates the nitrogen concentration compensation value through the PID algorithm model; the nitrogen concentration compensation value is sent to the valve body control unit to control the on and off of nitrogen, which is used to adjust the nitrogen concentration in the tank; data acquisition, PID control algorithm calculation and nitrogen concentration control are continuously performed until the nitrogen production concentration is stabilized within the preset value range.

[0074] When the nitrogen concentration exceeds the preset value, the control device uses the PID control algorithm to reduce the proportional coefficient to reduce the nitrogen concentration until the actual nitrogen value is within the preset value range; When the nitrogen concentration is lower than the preset value, the control device uses the PID control algorithm to increase the proportional coefficient to increase the nitrogen concentration until the actual nitrogen value is within the preset value range.

[0075] In some embodiments, the control device determines whether the nitrogen concentration is within a preset value range. If not, it generates a nitrogen concentration change curve graph of the equipment to be cut during the nitrogen use time period, and generates a nitrogen concentration horizontal line on the nitrogen concentration change curve graph according to the compensation interval, and calculates the area of several closed images enclosed by the nitrogen concentration change curve graph and the horizontal line.

[0076] Specifically, when the cutting equipment starts to use nitrogen, the control device starts to record the nitrogen concentration data corresponding to each time point, and when it is determined that the nitrogen concentration is not within the preset value range, a nitrogen concentration change curve is generated according to the recorded time and nitrogen concentration data; Generate a nitrogen concentration horizontal line on the nitrogen concentration change curve graph, the ordinate value of the horizontal line is a preset nitrogen concentration value, that is, the middle value of the nitrogen concentration compensation interval; Discretize the nitrogen concentration change curve and the nitrogen concentration horizontal line into a series of data points; The area between two adjacent data points is regarded as a trapezoid, the area of each trapezoid is calculated, and then the areas of all trapezoids are added together to obtain the total area of the closed image.

[0077] In the embodiment of the present invention, Figure 2 The figure shows the adjustment logic of the nitrogen purity control system during the laser cutting process, which mainly involves key operations such as nitrogen purity detection, adsorption time adjustment, and air branch control. The following are detailed steps: Set the initial value: Set the nitrogen purity to A%.

[0078] Purity detection and judgment: Use the mixed gas analyzer to detect the nitrogen purity every 5 seconds to determine whether it is within the set value A±1%. If the nitrogen purity meets the set value, it will directly enter the laser cutting machine cutting stage. If the nitrogen purity does not meet the set value, there are two situations: If it is greater than or equal to A+1%, it is determined whether the time interval between the last adsorption adjustment time and the current adjustment time reaches 120 seconds, and whether the time interval from the power-on is 120 seconds.

[0079] If the above two interval conditions are met, the adsorption time is increased by 2 seconds, and then the air branch is opened. If not, the air branch is opened directly.

[0080] If it is less than or equal to A-1%, turn off the air branch and also determine whether the time interval between the last adsorption adjustment time and the current adjustment time is 120 seconds, and whether the time interval from the power-on is 120 seconds.

[0081] If the two interval conditions are met, the adsorption time is reduced by 2 seconds, then the drain valve is opened and the cutting path valve is closed. If not, the drain valve is directly opened and the cutting path valve is closed.

[0082] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one 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 present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the purity of mixed gas in laser cutting, characterized in that: The steps include: S1: The control device receives interface parameters input by the user; S2: After receiving the start-up command input by the user, the control device performs initialization settings according to the values of the interface parameters and simultaneously receives the detection data transmitted in real time by the mixed gas analyzer; S3: The control device performs logical operations according to the detection data transmitted in real time by the mixed gas analyzer according to the preset logical rules, and calculates the control quantity based on the preset PID control algorithm. According to the logical operation results and the control quantity, the control device generates corresponding control instructions and transmits them to the valve body control unit; S4: The valve body control unit controls the outlet valve, the exhaust gas discharge valve and the adsorption time of the high-pressure module nitrogen generator according to the control instruction to adjust the nitrogen concentration; S5: Determine whether the nitrogen concentration reaches the set concentration value; If yes, maintain the current control state; If not, go to step S3.

2. The method for controlling the purity of mixed gas for laser cutting according to claim 1, characterized in that: The nitrogen purity is A, the control accuracy is ±K, and the logic rules in step S3 include: The first level of logic rules: judge whether the gas concentration meets the set concentration range. When the detection value AK≤X≤A+K, the gas concentration meets the set concentration range; The second logical rule: judge whether the gas concentration is lower than the set concentration range. When the detection value X<AK, the gas concentration is lower than the set concentration range; The third level logic rule: determine whether the time when the equipment is started or the last time the nitrogen purity is switched exceeds the system preset value.

3. The method for controlling the purity of mixed gas for laser cutting according to claim 2, characterized in that: Step S3 includes: The control module converts analog quantities into digital quantities for calculation. Combined with the nitrogen concentration, compressed gas pressure, adsorption time, pressure equalization time, and nitrogen purity alarm value set on the interface, it uses the pre-built PID control algorithm to calculate the control quantity and generate control instructions to the valve body control unit.

4. The method for controlling the purity of mixed gas for laser cutting according to claim 3, characterized in that: Step S3 further includes: The control device analyzes the current nitrogen concentration value and the input value on the interface, and calculates the nitrogen concentration compensation value through the PID control algorithm. The nitrogen concentration compensation value is sent to the valve body control unit to control the nitrogen on and off, which is used to adjust the nitrogen concentration in the tank. Data acquisition, PID control algorithm calculation and nitrogen concentration control are continuously performed until the nitrogen production concentration is stabilized within the preset value range. When the nitrogen concentration exceeds a preset value, the control device uses a PID control algorithm to reduce the proportional coefficient to reduce the nitrogen concentration until the actual nitrogen value is within the preset value range; When the nitrogen concentration is lower than the preset value, the control device uses the PID control algorithm to increase the proportional coefficient to increase the nitrogen concentration until the actual nitrogen value is within the preset value range.

5. The method for controlling the purity of mixed gas for laser cutting according to claim 4, characterized in that: Step S4 specifically includes: When the logic operation of the first-level logic rule passes, the valve control unit opens the outlet valve of the high-pressure module nitrogen generator according to the received control instruction and starts normal gas supply; the valve control unit continues to operate according to this control instruction until the logic operation of the first-level logic rule fails and enters the logic operation of the second-level logic rule; When the logic operation of the second-level logic rule passes, the valve body control unit opens the exhaust valve of the equipment according to the received control instruction, starts to empty the unqualified gas in the mixed gas process tank, and performs the logic operation of the third-level logic rule at the same time; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously increase the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, so as to reduce the nitrogen concentration until the adsorption time reaches the first set value.

6. The method for controlling the purity of mixed gas for laser cutting according to claim 5, characterized in that: Step S4 also includes: When the logic operation of the second-level logic rule fails, the valve body control unit opens the valve leading to the gas mixing process tank according to the received control instruction, reducing the nitrogen purity of the gas mixing process tank, and at the same time the control device performs the logic operation of the third-level logic rule; When the logical operation of the third-level logic rule is passed, the valve body control unit begins to continuously reduce the adsorption time of the high-pressure module nitrogen generator according to the preset single adjustment amount based on the received control instruction, thereby increasing the nitrogen concentration until the adsorption time reaches the second set value.

7. The method for controlling the purity of mixed gas for laser cutting according to claim 6, characterized in that: The method further includes: S6: When it is determined that the nitrogen concentration is not within the preset value range, a nitrogen concentration change curve graph of the equipment to be cut during the nitrogen use time period is generated, and a nitrogen concentration horizontal line is generated on the nitrogen concentration change curve graph according to the compensation interval, and the areas of several closed images enclosed by the nitrogen concentration change curve graph and the horizontal line are calculated.

8. The method for controlling the purity of mixed gas for laser cutting according to claim 7, characterized in that: Step S6 specifically includes: When the cutting equipment starts to use nitrogen, the control device starts to record the nitrogen concentration data corresponding to each time point. When it is determined that the nitrogen concentration is not within the preset value range, a nitrogen concentration change curve is generated according to the recorded time and nitrogen concentration data; Generate a nitrogen concentration horizontal line on the nitrogen concentration change curve graph, the ordinate value of the horizontal line is a preset nitrogen concentration value, that is, the middle value of the nitrogen concentration compensation interval; Discretize the nitrogen concentration change curve and the nitrogen concentration horizontal line into a series of data points; The area between two adjacent data points is regarded as a trapezoid, the area of each trapezoid is calculated, and then the areas of all trapezoids are added together to obtain the total area of the closed image.

9. A laser cutting mixed gas purity control system, characterized in that: It includes parameter input unit, control device, mixed gas analyzer, high-pressure module nitrogen generator and valve control unit; The user inputs interface parameters and startup instructions through the parameter input unit; Mixed gas analyzer, used to detect the purity of nitrogen in the pipeline; The control device is configured to receive input interface parameter values, including nitrogen purity, input gas pressure, input gas flow rate, output gas flow rate, output gas pressure, control accuracy, adsorption time, and AB tower switching time; upon receiving a startup instruction input by a user, perform initialization settings according to the interface parameter values, and simultaneously receive detection data transmitted in real time from a mixed gas analyzer; the control device performs logical operations according to pre-set logical rules based on the detection data transmitted in real time from the mixed gas analyzer, and simultaneously calculates a control quantity based on a preset PID control algorithm; generates corresponding control instructions based on the logical operation results and the control quantity, and transmits the instructions to the valve body control unit; The valve body control unit is used to control the outlet valve, exhaust gas discharge valve and adsorption time of the high-pressure module nitrogen making device according to the control instructions to adjust the nitrogen concentration.

10. The laser cutting mixed gas purity control system according to claim 9, characterized in that: The nitrogen purity is A, the control accuracy is ±K, and the logic rules include: The first level of logic rules: judge whether the gas concentration meets the set concentration range. When the detection value AK≤X≤A+K, the gas concentration meets the set concentration range; The second logical rule: judge whether the gas concentration is lower than the set concentration range. When the detection value X<AK, the gas concentration is lower than the set concentration range; The third level logic rule: determine whether the time when the equipment is started or the last time the nitrogen purity is switched exceeds the system preset value.

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