Supercritical CO2 minimal quantity lubrication nozzle selection regulation and control method and device for variable working condition machining

Abstract

The invention discloses a supercritical CO2 minimum quantity lubrication nozzle selection regulation and control method and device for variable working condition machining. The method comprises the following steps: calculating a theoretical gas cooling temperature difference under a corresponding machining condition based on working condition parameters of current cutting machining; calculating the average heat flux density required for cooling the cutting area to the target area; calculating the total heat absorbed by the jet flow from the cutting area; calculating an outlet area or a caliber range meeting a target nozzle; according to the outlet area or the caliber range, a matched nozzle is selected from a preset nozzle library; and if the plurality of nozzles meet the condition, selecting the nozzle with the caliber closest to the central value of the range. According to the method, the cutting machining parameters of machining equipment and the cooling requirement of the machined metal are continuously read, the most suitable cooling and lubricating nozzle caliber in the machining state is predicted, the suitable cooling and lubricating nozzle is rapidly selected and switched, the nozzle is accurately positioned to the cutting area, and the machining efficiency is improved. The cooling spraying mode can be dynamically switched according to the machining conditions.

Description

Technical Field

[0001] This invention relates to a nozzle selection and control method in the field of processing and manufacturing technology, and more particularly to a method for selecting and controlling a supercritical CO2 micro-lubrication nozzle in variable working condition processing, and also to a device for selecting and controlling a supercritical CO2 micro-lubrication nozzle in variable working condition processing. Background Technology

[0002] With the increasing demand for high-performance materials in high-end manufacturing fields such as aerospace and energy equipment, metal cutting faces severe challenges such as high cutting temperatures and rapid tool wear. Cooling and lubrication technology is crucial for controlling machining quality and improving efficiency. In particular, supercritical CO2 micro-lubrication technology has attracted attention due to its excellent cooling and environmental performance. However, in actual production, a workpiece often needs to undergo multiple machining steps consecutively, and its cutting parameters (such as speed, feed, and depth of cut) change dynamically due to different processes, resulting in changes in the thermal load of the cutting zone. The ideal cooling and lubrication effect is highly sensitive to the selection of nozzle diameter and jet parameters, and a single cooling solution is difficult to adapt to this "variable working condition" machining requirement.

[0003] In existing technologies, nozzle selection and switching primarily rely on manual experience. This is not only inefficient but also typically requires machine shutdown, interrupting the production process. During switching, if high-pressure residual gas in the pipeline is not safely released, there is a safety hazard of nozzle splashing and causing injury. Furthermore, most processing equipment is equipped with only a single fixed nozzle, whose cooling capacity is limited and cannot be adaptively adjusted. To cope with different heat loads, operators often tend to simply and inefficiently increase the CO2 supply pressure. This not only provides minimal cooling improvement after reaching the threshold, resulting in a huge waste of energy and resources, but also easily leads to prolonged high-load operation of the equipment. More importantly, a single cooling condition cannot accurately match changing working conditions, easily causing drastic temperature fluctuations in the cutting zone. Once the temperature exceeds the suitable range for material processing, it will directly lead to a series of process problems such as accelerated tool wear and decreased machining accuracy. Therefore, there is an urgent need for an intelligent control method and device that can automatically select and switch the optimal nozzle based on real-time working conditions. Summary of the Invention

[0004] To address the technical problems of low efficiency and limited cooling effect in existing intelligent nozzle control methods and devices, this invention provides a method and device for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working conditions.

[0005] This invention is achieved using the following technical solution: a method for selecting and controlling a supercritical CO2 micro-lubrication nozzle for variable working conditions, comprising the following steps: S1: Based on the current cutting process parameters, calculate the theoretical gas cooling temperature difference under the corresponding processing conditions using a cutting temperature prediction model; S2: Based on the cooling temperature difference, the thermal properties of the material being processed, and the heat source distribution characteristics of the cutting zone caused by different cutting parameters, calculate the average heat flux density required to cool the cutting zone to the target range; S3: Based on the heat flux density and the effective area of ​​the CO2 jet impacting the cutting wall, calculate the total heat that the jet needs to absorb from the cutting zone; S4: Based on the CO2 supply pressure and temperature, and combined with the total heat, CO2 supply side jet pressure and temperature, calculate the outlet area or diameter range that meets the target nozzle. S5: Select a matching nozzle from the preset nozzle library according to the outlet area or diameter range; if multiple nozzles meet the conditions, select the nozzle whose diameter is closest to the center value of the range.

[0006] This invention continuously reads the cutting parameters of the processing equipment and the cooling requirements of the processed metal to predict the most suitable cooling and lubrication nozzle diameter under the processing condition. It quickly selects the appropriate cooling and lubrication nozzle and accurately positions the nozzle to the cutting zone. Based on this, it feeds back to the CO2 industrial equipment under the selected nozzle to adjust the appropriate CO2 pressure according to the real-time cutting temperature. This enables the cooling spray mode to be dynamically switched according to the processing conditions, solving the technical problems of low efficiency and single cooling effect in existing intelligent nozzle control methods and devices.

[0007] As a further improvement to the above solution, in step S1, the working parameters include cutting speed. Tool feed rate Depth of cut, density of the workpiece material Thermal conductivity Tool geometry parameters and ambient temperature during the current cutting process The expression for the prediction model is: In the formula, This indicates the cooling temperature difference. Indicates the target cooling temperature. Indicates the heat distribution coefficient. It represents the main cutting force of the material during dry cutting. Indicates the depth of cut; the tool geometry parameters include the tool rake angle. Shear angle and the main cutting edge angle of the tool .

[0008] Further, in step S2, the formula for calculating the average heat flux density is: In the formula, This represents the heat flux density of CO2 on the rake face. This indicates the actual area of ​​the tool surface covered by the CO2 jet. Indicates the width of the cutting tool. , Represents the horizontal and vertical coordinates.

[0009] Furthermore, in step S3, the formula for calculating the total heat is: In the formula, This represents the total heat. This represents the jet radius of the CO2 jet as it is injected onto the surface of the cutting area. This represents the compensation coefficient.

[0010] Furthermore, in step S4, a diameter is selected from the diameter range for calculation, and the calculation formula is as follows: In the formula, Indicates the caliber, Indicates flow rate. Indicates the flow coefficient. Indicates standard state pressure, This indicates the specific heat capacity of CO2. Represents the gas constant. Indicates the specific heat ratio of CO2. Indicates atmospheric ambient temperature. This indicates the temperature parameter of the high-pressure CO2 supplied by the CO2 supply equipment. This indicates the specific enthalpy of the CO2 jet entering the cutting zone.

[0011] As a further improvement to the above scheme, the control method further includes the following steps: S6: During the cutting process, monitor the actual temperature of the cutting zone in real time; S7: If the actual temperature exceeds the preset target processing temperature range a certain number of times within a set time period, the prediction model and calculation parameters are updated according to the real-time monitoring data, and steps S1 to S5 are re-executed to dynamically correct and select a new target nozzle for switching.

[0012] Furthermore, the target processing temperature range is based on the ideal processing temperature of the material being processed or a temperature range preset according to the processing requirements.

[0013] This invention also provides a supercritical CO2 micro-lubrication nozzle selection and control device for variable working condition machining, which applies any of the above-described supercritical CO2 micro-lubrication nozzle selection and control methods for variable working condition machining. The device includes: The data acquisition module is used to acquire cutting process parameters, CO2 supply pressure and temperature, and real-time temperature of the cutting zone. A calculation and control module is connected to the data acquisition module and is used to execute the calculation steps in the method based on the acquired data, and generate nozzle selection and switching instructions; The nozzle execution module is connected to the calculation and control module and includes multiple nozzles of different diameters, a drive mechanism for moving the nozzles to the working position or retracting them, and a valve for controlling the flow on and off of each nozzle.

[0014] As a further improvement to the above solution, the data acquisition module includes an infrared thermal imager for monitoring the temperature of the cutting zone and a pressure and temperature transmitter for monitoring the pressure and temperature of the CO2 supply pipeline; the drive mechanism in the nozzle actuation module is a cylinder, and the valve is an electric switching valve.

[0015] As a further improvement to the above solution, the control device also includes a two-dimensional positioning slide, which is used to mount the nozzle actuation module and adjust its position relative to the cutting zone.

[0016] Compared with existing intelligent nozzle control methods and devices, the supercritical CO2 micro-lubrication nozzle selection and control method and device for variable working condition processing of the present invention has the following beneficial effects: 1. The supercritical CO2 micro-lubrication nozzle selection and control method for variable working conditions continuously reads the cutting parameters of the processing equipment and the cooling requirements of the processed metal to predict the most suitable cooling and lubrication nozzle diameter under the processing condition. It quickly selects and switches the appropriate cooling and lubrication nozzle and accurately positions the nozzle to the cutting zone. Based on this, the nozzle diameter is adjusted in real time according to the cutting temperature and CO2 supply pressure and temperature feedback. This enables the cooling spray mode to be dynamically switched according to the processing conditions, solving the technical problems of low efficiency and single cooling effect of existing intelligent nozzle control methods and devices.

[0017] 2. This method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable-condition machining achieves scientific and quantitative nozzle selection by establishing a theoretical calculation model from cutting conditions to nozzle parameters. This method overcomes the arbitrariness and uncertainty of traditional manual selection, enabling precise matching of the most suitable nozzle thermodynamic properties for specific cutting conditions. It optimizes cooling efficiency from the source, avoiding process problems caused by insufficient or excessive cooling.

[0018] 3. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable operating condition processing intelligently matches the optimal nozzle diameter, effectively reducing excessive dependence on CO2 supply pressure while meeting cooling requirements. This avoids blindly increasing system operating pressure to accommodate a single nozzle, thereby reducing the operating load and energy consumption of high-pressure fluid equipment, extending equipment lifespan, and achieving the green manufacturing goal of energy saving and consumption reduction.

[0019] 4. This supercritical CO2 micro-lubrication nozzle selection and control device for variable working conditions integrates rapid switching of multiple nozzles and real-time temperature feedback closed-loop control. When the cutting temperature exceeds the preset range due to changes in working conditions or prediction deviations, the system can automatically trigger the nozzle reselection and switching process without manual intervention or machine shutdown. This achieves continuous, adaptive, and stable control of cooling conditions during the cutting process, significantly improving the automation level and process reliability of machining.

[0020] 5. This invention provides a general method framework and modular device. Its core calculation model can be adapted to different materials (such as steel, titanium alloys, and high-temperature alloys) and tool types through correction coefficients, and its execution module is also compatible with various nozzle structures (such as round and square). This design gives it good process adaptability and scalability, making it easy to promote and apply in different machine tools and machining scenarios. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working conditions in Embodiment 1 of the present invention.

[0022] Figure 2 This is a structural diagram of the supercritical CO2 micro-lubrication nozzle selection and control device for variable working condition processing according to Embodiment 4 of the present invention.

[0023] Figure 3 for Figure 2 A side view of the nozzle execution module of the nozzle selection and control device.

[0024] Figure 4 for Figure 2 A top view of the nozzle actuation module of the nozzle selection and control device.

[0025] Symbol explanation: 1. Nozzle loading module; 2. Electric switching valve; 3. Diverter; 4. Cylinder; 5. Infrared thermal imager; 6. Integrated temperature and pressure transmitter; 7. Manual switching valve; 8. X-axis electric slide; 9. Y-axis electric slide. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Example 1 Please see Figure 1 This embodiment provides a method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable-condition machining. This method is applicable to CNC machine tools, machining centers, and other machining equipment requiring cooling spray. This method can be used alone to guide nozzle selection under different cutting parameter conditions, addressing the issue of unclear nozzle selection during experiments or machining processes. It can also be used in conjunction with a control device to select an appropriate machining nozzle to cool the cutting zone based on changes in cutting conditions. The nozzle selection and control method includes the following steps (S1-S7).

[0028] S1: Based on the current cutting process parameters, calculate the theoretical gas cooling temperature difference under the corresponding processing conditions using a cutting temperature prediction model. The processing parameters include the cutting speed. Tool feed rate Depth of cut, density of the workpiece material Thermal conductivity Tool geometry parameters and ambient temperature during the current cutting process .

[0029] In this embodiment, the nozzle switching device is connected to the processing equipment. If the processing equipment lacks a central control system, it is connected to an external computer to obtain changes in machine tool processing parameters. A cutting temperature prediction model for the cutting zone is constructed within the built-in PLC control system based on the changes in the processing equipment's operating conditions to obtain the theoretical gas cooling temperature difference under these processing conditions. Therefore, the expression for the prediction model is: In the formula, Indicates the cooling temperature difference. Indicates the target cooling temperature. Indicates the heat distribution coefficient. It represents the main cutting force of the material during dry cutting. Indicates the depth of cut; tool geometry parameters include the tool rake angle. Shear angle and the main cutting edge angle of the tool .

[0030] S2: Based on the cooling temperature difference, the thermophysical properties of the workpiece, and the heat source distribution characteristics of the cutting zone caused by different cutting parameters, calculate the average heat flux density required to cool the cutting zone to the target range. Based on the cutting zone jet cooling temperature difference obtained in the previous step, and combined with the thermophysical properties of the workpiece and the heat source distribution characteristics of the cutting zone caused by different cutting parameters, the average heat transfer flux density between the CO2 fluid and the heat source in the cutting zone can be calculated. This is used to establish the relationship between jet parameters and the CO2 jet cooling capacity; the specific formula for calculating the average heat flux density is as follows: In the formula, This represents the heat flux density of CO2 on the rake face. This indicates the actual area of ​​the tool surface covered by the CO2 jet. Indicates the width of the cutting tool. , Represents the horizontal and vertical coordinates.

[0031] S3: Based on the heat flux density and the effective area of ​​the CO2 jet impacting the cutting wall, calculate the total heat that the jet needs to absorb from the cutting zone. Based on the average heat flux density required to cool the cutting zone to the target range obtained in the previous step, combined with the effective area of ​​the CO2 jet impacting the cutting wall, the total heat absorbed by the jet from the cutting zone can be further obtained. This total heat reflects the actual heat absorption capacity of the CO2 supplied at the jet supply end. The specific formula for calculating the total heat is as follows: In the formula, Indicates total calories. This represents the jet radius of the CO2 jet as it is injected onto the surface of the cutting area. This represents the compensation coefficient.

[0032] S4: Based on the supply pressure and temperature of supercritical CO2, and combined with the total heat, CO2 supply-side jet pressure and temperature, calculate the outlet area or diameter range of the target nozzle. In this embodiment, the switching device is connected to a CO2 supply micro-lubrication device to obtain the CO2 supply-side jet pressure and temperature, thereby predicting the required CO2 nozzle diameter under these CO2 jet pressure and temperature conditions to ensure that the cutting zone temperature can be cooled to the predetermined temperature. A diameter is selected from the diameter range for calculation, and the calculation formula is: In the formula, Indicates caliber. Indicates flow rate. Indicates the flow coefficient. Indicates standard state pressure, This indicates the specific heat capacity of CO2. Represents the gas constant. Indicates the specific heat ratio of CO2. Indicates atmospheric ambient temperature. This indicates the temperature parameter of the high-pressure CO2 supplied by the CO2 supply equipment. This indicates the specific enthalpy of the CO2 jet entering the cutting zone.

[0033] S5: Select a matching nozzle from a preset nozzle library based on the outlet area or diameter range; if multiple nozzles meet the conditions, select the nozzle with the diameter closest to the center value of the range. In this embodiment, the relevant dimensions of the corresponding nozzle can be calculated based on the area of ​​the selected nozzle obtained in the previous step. The nozzle type can be determined according to different applications. For example, if the CO2 jet is to surround the cutting area as much as possible, a square nozzle can be selected; if the CO2 jet is concentrated for fixed-point cooling, a round nozzle can be selected. This method uses a round nozzle to calculate the relevant dimensions.

[0034] The method in this embodiment can be applied alone to guide the selection of a single nozzle under different cutting parameter conditions, in order to solve the problem of unclear nozzle selection during corresponding experiments or cutting processes. It can also be used in conjunction with the nozzle selection and control device proposed in this invention to realize automatic nozzle matching and switching based on cutting conditions, so as to achieve appropriate and stable control of the temperature in the cutting area.

[0035] In summary, compared with existing intelligent nozzle control methods, the supercritical CO2 micro-lubrication nozzle selection and control method for variable working conditions in this embodiment has the following advantages: 1. This method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable-condition machining continuously reads the cutting parameters of the machining equipment and the cooling requirements of the processed metal. It predicts the most suitable cooling and lubrication nozzle diameter for the given machining condition, quickly selects the appropriate nozzle, and precisely positions the nozzle in the cutting zone. Based on real-time feedback of the cutting temperature, CO2 supply pressure, and temperature, the nozzle diameter is adjusted, enabling dynamic switching of the cooling spray mode according to machining conditions. This solves the technical problems of low efficiency and limited cooling effect in existing intelligent nozzle control methods and devices. This method effectively overcomes the problems of manual nozzle selection, low efficiency, and large temperature fluctuations in the cutting zone caused by limited nozzle cooling effect in existing high-pressure fluid micro-lubrication technology-assisted cutting or experiments.

[0036] 2. This method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable-condition machining achieves scientific and quantitative nozzle selection by establishing a theoretical calculation model from cutting conditions to nozzle parameters. This method overcomes the arbitrariness and uncertainty of traditional manual selection, enabling precise matching of the most suitable nozzle thermodynamic properties for specific cutting conditions. It optimizes cooling efficiency from the source, avoiding process problems caused by insufficient or excessive cooling.

[0037] 3. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable operating condition processing intelligently matches the optimal nozzle diameter, effectively reducing excessive dependence on CO2 supply pressure while meeting cooling requirements. This avoids blindly increasing system operating pressure to accommodate a single nozzle, thereby reducing the operating load and energy consumption of high-pressure fluid equipment, extending equipment lifespan, and achieving the green manufacturing goal of energy saving and consumption reduction.

[0038] Example 2 This embodiment provides a method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable working condition machining. This method adds steps S6 and S7 to the nozzle selection and control method in Embodiment 1, as detailed below.

[0039] S6: During the cutting process, monitor the actual temperature of the cutting zone in real time.

[0040] S7: If the actual temperature exceeds the preset target processing temperature range a certain number of times within the set time period, the prediction model and calculation parameters are updated based on real-time monitoring data, and steps S1 to S5 are re-executed to dynamically correct and select a new target nozzle for switching. The target processing temperature range is based on the ideal processing temperature of the material being processed or a preset temperature range according to the processing requirements.

[0041] Example 3 This embodiment provides a method for selecting and controlling supercritical CO2 micro-lubrication nozzles in variable-condition machining. This method adds some steps to the nozzle selection and control method in Embodiment 1. In this embodiment, a circular nozzle is used to calculate relevant dimensions.

[0042] Before the processing begins, based on each step of the continuous processing by the processing equipment... The corresponding cutting parameters, such as cutting speed Tool feed rate and depth of cut Thermal conductivity of the workpiece material to be cooled and the ideal processing temperature range or artificially set expected temperature period for the target cooling material. .

[0043] The temperature difference range required for jet cooling during the processing of the target material can be obtained from the formula in step S1. .

[0044] Based on the actual temperature and pressure parameters supplied by the supercritical CO2 supply equipment, and combined with the calculation formulas in steps S2, S3, and S4, the range of nozzle diameter selection that meets the requirements of the current cutting conditions can be obtained. .

[0045] Based on the CO2 injection nozzle library compatible with this device, within the above-mentioned nozzle diameter selection range Select the appropriate nozzle: If the nozzle diameter loaded by this device satisfy If the nozzle is suitable for cutting operations, then the nozzle is determined to be suitable for cutting operations. j Applicable to current cutting conditions.

[0046] If two or more nozzles loaded by this device meet the above conditions, the system further selects nozzles based on the degree of matching between the nozzle diameter and the target cooling temperature difference range. To ensure more stable temperature control of the cutting zone during subsequent processing and to keep temperature fluctuations within the expected temperature range, a nozzle with a diameter closer to the center value of the range is selected as the target nozzle. That is, a nozzle that satisfies the following relationship is selected as the target nozzle: in, Indicates the target nozzle number. It is the center value of the caliber interval, that is: Example 4 Please see Figure 2 , Figure 3 as well as Figure 4 This embodiment provides a supercritical CO2 micro-lubrication nozzle selection and control device for variable working condition machining. This device applies any one of the supercritical CO2 micro-lubrication nozzle selection and control methods for variable working condition machining described in Embodiments 1-3. The device includes a data acquisition module, a calculation and control module, a nozzle execution module, and a two-dimensional positioning slide (positioning module).

[0047] The data acquisition module is used to acquire cutting process parameters, CO2 supply pressure and temperature, and real-time temperature of the cutting zone. The module includes an infrared thermal imager 5 (infrared temperature detector), a temperature and pressure integrated transmitter 6, and a manual on / off valve 7. The infrared thermal imager 5 monitors the cutting zone temperature, the temperature and pressure integrated transmitter 6 monitors the actual pressure and temperature of the supercritical CO2 supply pipeline, and the manual on / off valve 7 is used to manually control the on / off state of the CO2 supply pipeline. This allows for real-time monitoring of temperature fluctuations in the cutting zone and the supply temperature of the supercritical CO2 supply equipment. With pressure parameters This provides data support for nozzle selection and jet parameter control.

[0048] The calculation and control module connects to the data acquisition module and is used to execute calculation steps in the method based on the acquired data, and generate nozzle selection and switching instructions. The calculation and control module mainly communicates with the corresponding experimental or processing platform to obtain the processing parameters of the equipment under different processes, and selects the nozzle diameter after obtaining the corresponding processing parameters, and sends corresponding control signals and nozzle posture adjustments to the nozzle control device to achieve rapid nozzle response.

[0049] The nozzle execution module is connected to the calculation and control module and includes multiple nozzles of different diameters, a drive mechanism to move the nozzles to the working position or retract them, and valves to control the flow on and off of each nozzle. The drive mechanism in the nozzle execution module is a cylinder, and the valves are electrically operated on / off valves 2. In this embodiment, the nozzle execution module mainly consists of N different types of selectable nozzles, 5 nozzle loading modules 1, a fluid diversion device 3, 5 fluid control switches, and corresponding nozzle drive cylinders 4. The connecting pipes between the execution module components are flexible hoses, which can contract or bend within permissible limits as the nozzle position changes.

[0050] N different types of selectable nozzles are used to provide injection schemes with different diameters or structures; 5 nozzle loading modules 1 are used to accommodate the nozzles and load the target nozzles into the cooling area upon command; fluid distribution device 3 is connected to the CO2 main pipeline to distribute supercritical CO2 to each nozzle unit. 5 fluid control switches are connected to the corresponding nozzle units to independently open or close the injection path of the corresponding nozzles; each nozzle drive cylinder 4 is used to drive the extension angle and retraction of the corresponding nozzle, realizing automatic nozzle selection, positioning and switching.

[0051] The two-dimensional positioning slide is used to mount the nozzle actuation module and adjust its position relative to the cutting zone. The two-dimensional positioning slide mainly includes an X-axis slide 8, a Y-axis slide 9, and a base. The base is primarily responsible for connecting the device and ensuring its stability during operation. The X-axis slide 8 and Y-axis slide 9 are mainly responsible for adjusting the position of the device relative to the relevant experimental platform or processing equipment, ensuring that the nozzle can reach the predetermined area for cooling and lubrication during the relevant process.

[0052] Example 5 This embodiment provides a method for selecting and controlling a supercritical CO2 micro-lubrication nozzle for variable working conditions. It is used in conjunction with the control device in Embodiment 4, and adds some steps based on Embodiment 3. The specific details are as follows.

[0053] In the iAfter the cutting operation begins, the temperature in the cutting zone fluctuates frequently within the expected temperature range due to initial thermal load fluctuations and errors in cutting temperature prediction. The temperature may intermittently or continuously exceed the expected range. This device uses a thermal imager in the data detection module to detect the peak temperature of the cutting zone in real time. If at the set time Within the specified range, if the peak temperature of the cutting zone exceeds the set number of times N, the system control module first calls the data detection module to obtain the cutting zone temperature. Average temperature update forecast temperature within the time period The system then modifies the target cooling requirements based on the model in Example 1. Subsequently, the system determines the target nozzle number that matches the current operating conditions according to the pre-selected nozzle diameter range and optimization rules, and replaces the nozzle through the nozzle selection execution module.

[0054] Specifically, the system controls the electric switch valve 2 corresponding to the original working nozzle to close and drives the cylinder 4 corresponding to the original working nozzle to retract to complete the nozzle removal. At the same time, it drives the cylinder 4 corresponding to the target nozzle to extend and adjusts the X-axis slide 8 and Y-axis slide 9 to load it into the cooling area. The corresponding fluid control switch is turned on so that the supercritical CO2 jet is output to the cutting area with matching pressure and flow rate, thereby realizing continuous, stable and adaptive control of the temperature of the cutting area, ensuring that the thermal state and machining accuracy of the machining process meet the expected requirements.

[0055] To ensure part accuracy, a single part needs to be finished on multiple surfaces under the same clamping conditions. Under different machining conditions, parameters such as cutting speed, feed rate, depth of cut, and tool condition often need to be adjusted. In the... i After the first cutting condition is completed, the machining process enters the next... i+1 During the machining process, parameters such as cutting speed, feed rate, depth of cut, and tool condition often change under different machining conditions, and the cutting temperature will change accordingly. The previous method can be repeated to adjust and replace the corresponding nozzles to stabilize the cutting temperature within the original expected temperature range.

[0056] Example 6 This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements any one of the supercritical CO2 micro-lubrication nozzle selection and control methods for variable working condition machining in Embodiments 1, 2, and 3.

[0057] The method in Example 1 can be applied in software form, such as by designing it as a standalone program and installing it on a computer terminal, which can be a computer, smartphone, control system, or other IoT device. Alternatively, the method in Example 1 can be designed as an embedded program and installed on a computer terminal, such as on a microcontroller.

[0058] Example 7 This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, it implements the steps of the supercritical CO2 micro-lubrication nozzle selection and control method for variable working condition machining as described in Embodiment 1.

[0059] When applying the method of Example 1, it can be applied in the form of software, such as by designing it as a program that can run independently on a computer-readable storage medium. The computer-readable storage medium can be a USB flash drive, designed as a USB security token, and the program can be designed to start the entire method through an external trigger.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for selecting and controlling a supercritical CO2 micro-lubrication nozzle in variable working condition machining, characterized in that, It includes the following steps: S1: Based on the current cutting process parameters, calculate the theoretical gas cooling temperature difference under the corresponding processing conditions using a cutting temperature prediction model; S2: Based on the cooling temperature difference, the thermal properties of the material being processed, and the heat source distribution characteristics of the cutting zone caused by different cutting parameters, calculate the average heat flux density required to cool the cutting zone to the target range; S3: Based on the heat flux density and the effective area of ​​the CO2 jet impacting the cutting wall, calculate the total heat that the jet needs to absorb from the cutting zone; S4: Based on the CO2 supply pressure and temperature, and combined with the total heat, CO2 supply side jet pressure and temperature, calculate the outlet area or diameter range that meets the target nozzle. S5: Select a matching nozzle from the preset nozzle library according to the outlet area or diameter range; if multiple nozzles meet the conditions, select the nozzle whose diameter is closest to the center value of the range.

2. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 1, characterized in that, In step S1, the operating parameters include cutting speed. Tool feed rate Depth of cut, density of the workpiece material Thermal conductivity Tool geometry parameters and ambient temperature during the current cutting process The expression for the prediction model is: ； In the formula, This indicates the cooling temperature difference. Indicates the target cooling temperature. Indicates the heat distribution coefficient. It represents the main cutting force of the material during dry cutting. Indicates the depth of cut; the tool geometry parameters include the tool rake angle. Shear angle and the main cutting edge angle of the tool .

3. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 2, characterized in that, In step S2, the formula for calculating the average heat flux density is: ； In the formula, This represents the heat flux density of CO2 on the rake face. This indicates the actual area of ​​the tool surface covered by the CO2 jet. Indicates the width of the cutting tool. , Represents the horizontal and vertical coordinates.

4. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 3, characterized in that, In step S3, the formula for calculating the total heat is: ； In the formula, This represents the total heat. This represents the jet radius of the CO2 jet as it is injected onto the surface of the cutting area. This represents the compensation coefficient.

5. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 4, characterized in that, In step S4, a diameter is selected from the diameter range for calculation, and the calculation formula is as follows: ； In the formula, Indicates the caliber, Indicates flow rate. Indicates the flow coefficient. Indicates standard state pressure, This indicates the specific heat capacity of CO2. Represents the gas constant. Indicates the specific heat ratio of CO2. Indicates atmospheric ambient temperature. This indicates the temperature parameter of the high-pressure CO2 supplied by the CO2 supply equipment. This indicates the specific enthalpy of the CO2 jet entering the cutting zone.

6. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 1, characterized in that, The control method further includes the following steps: S6: During the cutting process, monitor the actual temperature of the cutting zone in real time; S7: If the actual temperature exceeds the preset target processing temperature range a certain number of times within a set time period, the prediction model and calculation parameters are updated according to the real-time monitoring data, and steps S1 to S5 are re-executed to dynamically correct and select a new target nozzle for switching.

7. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 6, characterized in that, The target processing temperature range is based on the ideal processing temperature of the material being processed or a preset temperature range according to the processing requirements.

8. A device for selecting and controlling a supercritical CO2 micro-lubrication nozzle for variable working condition machining, characterized in that, Its application is the supercritical CO2 micro-lubrication nozzle selection and control method for variable working condition machining as described in any one of claims 1-7, wherein the device comprises: The data acquisition module is used to acquire cutting process parameters, CO2 supply pressure and temperature, and real-time temperature of the cutting zone. A calculation and control module, which is connected to the data acquisition module, is used to execute the calculation steps in the method based on the acquired data and generate nozzle selection and switching instructions; The nozzle execution module is connected to the calculation and control module and includes multiple nozzles of different diameters, a drive mechanism for moving the nozzles to the working position or retracting them, and a valve for controlling the flow on and off of each nozzle.

9. The method for selecting and controlling supercritical CO2 micro-lubrication nozzles for variable working condition machining as described in claim 8, characterized in that, The data acquisition module includes an infrared thermal imager for monitoring the temperature of the cutting zone and a pressure and temperature transmitter for monitoring the pressure and temperature of the CO2 supply pipeline; the drive mechanism in the nozzle actuation module is a cylinder, and the valve is an electric switching valve.

10. The supercritical CO2 micro-lubrication nozzle selection and control device for variable working condition machining as described in claim 8, characterized in that, The control device also includes a two-dimensional positioning slide, which is used to mount the nozzle actuation module and adjust its position relative to the cutting zone.

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