Supercritical CO2 and ultrasonic combined machining system and control method thereof, machine tool

Abstract

The application discloses a supercritical CO2 and ultrasonic compound machining system and a control method and machine tool thereof. The system comprises a supercritical CO2 supply unit, a control module and an ultrasonic machining device. The control module is electrically connected with the supercritical CO2 supply unit, and the control module is electrically connected with the ultrasonic machining device. The control module is further configured to control the process parameters of the supercritical CO2 to dynamically adjust within a preset range following the ultrasonic parameters according to the corresponding relationship between the process parameters of the supercritical CO2 and the ultrasonic parameters. The process parameters of the supercritical CO2 include the supercritical CO2 pressure P, and the ultrasonic parameters include the ultrasonic amplitude A and the ultrasonic vibration frequency f. The supercritical CO2 pressure is controlled to dynamically adjust following the ultrasonic parameters, the jetting effect of the supercritical CO2 is improved, the machining effect and the machining quality are ensured, the machining efficiency and the machining precision are improved, and the cost is effectively reduced.

Description

Technical Field

[0001] This application relates to the field of cutting and machining technology, and in particular to a supercritical CO2 and ultrasonic composite machining system and its control method, as well as a machine tool. Background Technology

[0002] High-strength steel, high-temperature alloys, and titanium alloys, among other difficult-to-machine materials, typically possess advantages such as high strength, corrosion resistance, oxidation resistance, and excellent high-temperature performance, making them widely used in critical equipment in important fields like aerospace, nuclear energy, and military. However, while meeting high-performance requirements, the difficulty in machining these materials and the poor control of existing cutting equipment lead to severe tool wear, reduced tool life, and high cutting zone temperatures, resulting in unsatisfactory machining effects and quality. Traditional casting cutting fluid machining cannot solve these problems. Furthermore, cutting fluids contain mineral oil and various chemical additives, and their large-scale use can harm the environment and operator health, while waste disposal increases production costs. In recent years, supercritical CO2, being green and non-toxic, has been widely used in extraction and has also been applied to machining. However, to ensure cooling effects, large amounts of supercritical CO2 are consumed, resulting in some waste and low cooling efficiency.

[0003] Ultrasonic machining technology can not only improve the surface roughness and machining accuracy of the machined surface, but also reduce cutting resistance and extend tool life. Therefore, ultrasonic machining is widely used. Summary of the Invention

[0004] This application provides a supercritical CO2 and ultrasonic composite machining system and its control method, as well as a machine tool, to improve the machining effect and quality of difficult-to-machine materials.

[0005] According to one aspect of this application, a supercritical CO2 and ultrasonic composite processing system is provided, comprising: a supercritical CO2 supply unit, a control module, and an ultrasonic processing device; wherein the control module is electrically connected to the supercritical CO2 supply unit and the ultrasonic processing device;

[0006] The control module is further configured to: control the supercritical CO2 process parameters to dynamically adjust within a preset range according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters, wherein the supercritical CO2 process parameters include supercritical CO2 pressure P, and the ultrasonic parameters include the ultrasonic amplitude A and ultrasonic vibration frequency f of the ultrasonic processing device.

[0007] Optionally, the relationship between the supercritical CO2 pressure P and the ultrasonic vibration frequency f is as follows: when the ultrasonic vibration frequency f is within a first preset ultrasonic vibration frequency range, the ultrasonic vibration frequency f is negatively correlated with the supercritical CO2 pressure P; when the ultrasonic vibration frequency f is within a second preset ultrasonic vibration frequency range, the ultrasonic vibration frequency f is positively correlated with the supercritical CO2 pressure P; and any value within the first preset ultrasonic vibration frequency range is less than any value within the second preset ultrasonic vibration frequency range.

[0008] Optionally, the first preset ultrasonic vibration frequency range is 16KHz≤f<30KHz, and the second preset ultrasonic vibration frequency range is 30KHz≤f≤50KHz.

[0009] Optionally, when 16kHz≤f<30kHz, 8MPa<P≤15MPa, and f is negatively correlated with P; when 30kHz≤f≤50kHz, P≥8MPa, and f is positively correlated with P.

[0010] Optionally, the correspondence between the supercritical CO2 pressure P and the ultrasonic amplitude A is as follows: when the ultrasonic amplitude A is within a first preset ultrasonic amplitude range, the ultrasonic amplitude A is negatively correlated with the supercritical CO2 pressure P; when the ultrasonic amplitude A is within a second preset ultrasonic amplitude range, the ultrasonic amplitude A is positively correlated with the supercritical CO2 pressure P; and any value within the first preset ultrasonic amplitude range is less than any value within the second preset ultrasonic amplitude range.

[0011] Optionally, the first preset ultrasonic amplitude range is 0.5μm≤A<10μm, and the second preset ultrasonic amplitude range is A≥10μm.

[0012] Optionally, when 0.5μm≤A<10μm, 8MPa<P≤15MPa, and A and P are negatively correlated; when A≥10μm, P≥8MPa, and A and P are positively correlated.

[0013] Optionally, the control module is configured to: control the supercritical CO2 pressure within a preset pressure range, control the ultrasonic amplitude within a preset ultrasonic amplitude range, and control the ultrasonic vibration frequency within a preset ultrasonic vibration frequency range, wherein the preset pressure range is P≥8MPa, the preset ultrasonic amplitude range is A≥0.5μm, and the preset ultrasonic vibration frequency is 16KHz≤f≤50KHz.

[0014] Optionally, it also includes a micro-lubrication supply unit, which is connected to the output pipeline of the supercritical CO2 supply unit for mixing the lubricating oil provided by the micro-lubrication supply unit with the supercritical CO2 provided by the supercritical CO2 supply unit. The micro-lubrication supply unit is also electrically connected to the control module.

[0015] The control module is also configured to control the output pressure of the lubricating oil from the micro-lubrication supply unit to be greater than the supercritical CO2 pressure.

[0016] Optionally, it also includes a micro-lubrication supply unit and a mixing module. Both the micro-lubrication supply unit and the supercritical CO2 supply unit are connected to the mixing module to provide lubricating oil and supercritical CO2 to the mixing module. The micro-lubrication supply unit is also electrically connected to the control module.

[0017] Optionally, it also includes a micro-lubrication supply unit, wherein the supercritical CO2 supply unit is connected to the output pipeline of the micro-lubrication supply unit for mixing the lubricating oil provided by the micro-lubrication supply unit with the supercritical CO2 provided by the supercritical CO2 supply unit, and the micro-lubrication supply unit is also electrically connected to the control module;

[0018] The control module is also configured to control the output pressure of the lubricating oil from the micro-lubrication supply unit to be less than the supercritical CO2 pressure.

[0019] Optionally, the end of the output pipeline of the supercritical CO2 supply unit is connected to the ultrasonic processing device.

[0020] According to another aspect of this application, a control method is provided for a supercritical CO2 and ultrasonic composite processing system as described in the first aspect. The control method includes: controlling the supercritical process parameters to dynamically adjust within a preset range according to the correspondence between supercritical process parameters and ultrasonic parameters, wherein the supercritical process parameters include supercritical pressure, and the ultrasonic parameters include ultrasonic amplitude and ultrasonic vibration frequency.

[0021] According to another aspect of this application, a machine tool is provided, which includes a supercritical CO2 and ultrasonic composite machining system as described in the first aspect.

[0022] The technical solution of this application embodiment provides a supercritical CO2 and ultrasonic composite machining system and its control method and machine tool. The supercritical CO2 and ultrasonic composite machining system includes: a supercritical CO2 supply unit, a control module, and an ultrasonic machining device. The control module is electrically connected to the supercritical CO2 supply unit to control the process parameters of the supercritical CO2 supplied by the supercritical CO2 supply unit and to control the supercritical CO2 supply unit to provide supercritical CO2 to the machining area. The control module is also electrically connected to the ultrasonic machining device to control the ultrasonic machining device to provide ultrasonic vibration and to acquire the ultrasonic parameters of the ultrasonic machining device. The control module is configured to: based on the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters, control the supercritical CO2 process parameters to dynamically adjust in accordance with the ultrasonic parameters. The supercritical CO2 process parameters include supercritical CO2 pressure, and the ultrasonic parameters include ultrasonic amplitude and ultrasonic vibration frequency. Therefore, by combining supercritical CO2 with ultrasound, green machining of difficult-to-machine materials can be achieved. Furthermore, by controlling the process parameters of supercritical CO2 and dynamically adjusting them according to the correspondence between the supercritical CO2 process parameters and the ultrasound parameters, the jetting effect of supercritical CO2 is improved, thereby ensuring machining effect and quality, improving machining efficiency and precision, and effectively reducing costs. In addition, using supercritical CO2 is environmentally friendly and pollution-free, has good cooling effect, effectively reduces the temperature of the cutting zone, and ultrasonic machining can also improve surface roughness and reduce burr problems.

[0023] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the principle structure of a supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0026] Figure 2 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0027] Figure 3This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0028] Figure 4 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0029] Figure 5 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0030] Figure 6 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0031] Figure 7 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0032] Figure 8 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0033] Figure 9 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0034] Figure 10 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application;

[0035] Figure 11 This is a flowchart of a control method for a supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application.

[0036] Figure 12 This is a schematic diagram of the overall process of a supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application; Detailed Implementation

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] Figure 1 This is a schematic diagram of the principle structure of a supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application. (Reference) Figure 1 The supercritical CO2 and ultrasonic composite processing system includes: a supercritical CO2 supply unit 10, a control module 20, and an ultrasonic processing device 30; wherein, the control module 20 is electrically connected to the supercritical CO2 supply unit and is used to control the supercritical CO2 supply unit to provide supercritical CO2 to the processing area, and to control the process parameters of the supercritical CO2 of the supercritical CO2 supply unit; the control module is electrically connected to the ultrasonic processing device to acquire the ultrasonic parameters of the ultrasonic processing device, and to control the ultrasonic processing device to provide ultrasonic vibration;

[0040] The control module 20 is configured to: control the supercritical CO2 process parameters to dynamically adjust within a preset range according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters. The supercritical CO2 process parameters include supercritical CO2 pressure P, and the ultrasonic parameters include ultrasonic amplitude A and ultrasonic vibration frequency f.

[0041] The output pipe of the supercritical CO2 supply unit 10 can be connected to the ultrasonic processing device 30 to provide supercritical CO2 to the processing area through the internal cooling channel of the ultrasonic processing device 30. Specifically, after passing through the internal cooling channel of the ultrasonic processing device, the supercritical CO2 is further supplied to the processing area through the cooling channel in the internally cooled tool holder or internally cooled tool, forming internal cooling. Of course, the supercritical CO2 supply unit can also be directly connected to an external nozzle to provide supercritical CO2 to the processing area, forming external cooling. That is, in external cooling, the supercritical CO2 does not pass through the cooling channel of the ultrasonic processing device. This part is no different from the prior art, so it will not be elaborated on further. The following description uses internal cooling as an example, unless otherwise stated.

[0042] For example, the ultrasonic machining device 30 provides ultrasonic vibration and, based on the supercritical CO2 supplied by the supercritical CO2 supply unit 10, combines ultrasound to perform cutting machining on the workpiece. The workpiece can be a difficult-to-machine material such as high-strength steel, high-temperature alloys, and titanium alloys. The ultrasonic machining device 30 may include a spindle, an ultrasonic generator, a transmitting unit, an ultrasonic tool holder and a cutting tool mounted on the spindle (or the transducer portion may be installed inside the spindle, connected to the spindle using a precision tool holder). Furthermore, the transmitting unit can be installed inside the spindle, directly at the front end of the spindle, or externally mounted on the spindle housing via a clamp. After receiving the ultrasonic signal from the ultrasonic generator, the ultrasonic transmitting unit transmits it via wired or wireless means to the receiving unit of the ultrasonic tool holder, thereby transmitting the ultrasonic signal. This ultrasonic signal enables the ultrasonic tool holder to generate ultrasonic vibration, thus performing ultrasonic machining on the workpiece.

[0043] The supercritical CO2 supply unit 10 is used to provide supercritical CO2. The specific implementation method of supercritical CO2 output by the supercritical CO2 supply unit 10 can be: heating and pressurizing low-temperature and low-pressure CO2, so that the low-temperature and low-pressure CO2 enters the supercritical state through heating and pressurization, thereby obtaining supercritical CO2.

[0044] The control module 20 can be a CNC system, PLC or other controller, and the specific configuration can be set according to the actual situation. No specific limitations are made here.

[0045] The supercritical CO2 pressure can be obtained by installing a pressure detection unit on the pipeline between the supercritical CO2 supply unit and the ultrasonic processing device. The control module 20 obtains ultrasonic parameters from the ultrasonic processing device 30, and then controls the supercritical CO2 process parameters of the supercritical CO2 supply unit 10 according to the aforementioned ultrasonic parameters. Specifically, the ultrasonic parameters include the ultrasonic vibration frequency fed back to the control module 20 by the ultrasonic generator, and also include the ultrasonic amplitude detected by the tool parameter monitoring unit installed at the tool end.

[0046] For example, the control module is electrically connected to the ultrasonic generator and the tool parameter monitoring unit. The ultrasonic generator and the tool parameter monitoring unit feed back ultrasonic parameters to the control module, so that the control module adjusts the supercritical CO2 pressure of the supercritical CO2 supply unit according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters. In addition, the control module is also electrically connected to the ultrasonic generator and is used to control the start or stop of the ultrasonic generator to control whether it outputs ultrasonic signals to the transmitting unit.

[0047] The control module 20 is also used to control the adjustment of the ultrasonic parameters of the ultrasonic processing device 30 so as to control the ultrasonic parameters within a preset range.

[0048] The control module 20 is electrically connected to the ultrasonic processing device 30 and is also used to control the start or stop of the ultrasonic processing device 30, as well as air blowing, tool changing, etc.

[0049] Regarding the correspondence between supercritical process parameters and ultrasonic parameters, during ultrasonic-assisted machining, the presence of acoustic impedance between the tool and workpiece generates a significant amount of heat due to ultrasonic vibration. Furthermore, the periodic separation of the tool and chips during ultrasonic-assisted machining carries away heat. Therefore, when the amplitude is constant, initially, as the ultrasonic vibration frequency increases, the periodic separation of the tool and workpiece results in heat carried away by the separation exceeding the heat generated by the ultrasonic waves and the acoustic impedance of the tool and workpiece. This helps reduce the amount of carbon dioxide injected, meaning that a higher supercritical CO2 pressure is not required to meet the cooling needs. However, as the ultrasonic vibration frequency continues to increase, the heat generated by the ultrasonic waves and the acoustic impedance of the tool and workpiece increases dramatically and exceeds the heat carried away by the periodic separation. At this point, the amount of carbon dioxide injected needs to be increased, requiring a relatively higher supercritical CO2 pressure to meet the cooling requirements and ensure the stability of ultrasonic machining.

[0050] When the ultrasonic vibration frequency is constant, in the early stages, as the ultrasonic amplitude gradually increases, the tool and workpiece periodically separate. The heat carried away by this periodic separation is greater than the heat generated by the ultrasonic waves and the acoustic impedance of the tool and workpiece, which helps to reduce the amount of carbon dioxide injected, meaning that the cooling requirements can be met without a high supercritical CO2 pressure. However, as the ultrasonic amplitude continues to increase, the heat generated by the ultrasonic waves and the acoustic impedance of the tool and workpiece increases sharply and exceeds the heat carried away by the periodic separation. At this point, it is necessary to increase the amount of carbon dioxide injected, meaning that a relatively high supercritical CO2 pressure is required to meet the cooling requirements and ensure the stability of ultrasonic machining.

[0051] Optionally, the control module 20 is further configured to: when the ultrasonic amplitude A remains constant, the ultrasonic vibration frequency f is negatively correlated with the supercritical CO2 pressure P when the ultrasonic vibration frequency f is within the first preset ultrasonic vibration frequency range, and positively correlated with the supercritical CO2 pressure P when the ultrasonic vibration frequency f is within the second preset ultrasonic vibration frequency range, and any value within the first preset ultrasonic vibration frequency range is less than any value within the second preset ultrasonic vibration frequency range.

[0052] The first preset ultrasonic vibration frequency range is 16KHz≤f<30KHz, and the second preset ultrasonic vibration frequency range is 30KHz≤f≤50KHz.

[0053] Moreover, when 16kHz≤f<30kHz, 8MPa<P≤15MPa, and f is negatively correlated with P; when 30kHz≤f≤50kHz, P≥8MPa, and f is positively correlated with P.

[0054] Optionally, the control module is further configured to: keep the ultrasonic amplitude A constant, and the ultrasonic vibration frequency is a first preset ultrasonic vibration frequency f1, the supercritical CO2 pressure is a first preset pressure P1, and the first preset ultrasonic vibration frequency is negatively correlated with the first preset pressure.

[0055] The first preset ultrasonic vibration frequency f1 satisfies: 16 ≤ f1 < 30 kHz, and the first preset pressure P1 satisfies: 8 MPa < P1 ≤ 15 MPa. It should be noted that the values ​​of the first preset ultrasonic vibration frequency and the first preset pressure can be set according to actual conditions, and are not specifically limited here.

[0056] Optionally, the control module is further configured to: keep the ultrasonic amplitude A constant, and the ultrasonic vibration frequency is a second preset ultrasonic vibration frequency f2, the supercritical CO2 pressure is a second preset pressure P2, and the second preset ultrasonic vibration frequency is positively correlated with the second preset pressure.

[0057] The second preset ultrasonic vibration frequency f2 satisfies: 30kHz ≤ f2 ≤ 50kHz, and the second preset pressure P2 satisfies: P2 ≥ 8MPa. It should be noted that the values ​​of the second preset ultrasonic vibration frequency and the second preset pressure can be set according to actual conditions and are not specifically limited here.

[0058] Optionally, the control module 20 is further configured to: when the ultrasonic vibration frequency f remains constant, the ultrasonic amplitude A is negatively correlated with the supercritical CO2 pressure P when the ultrasonic amplitude A is within the first preset ultrasonic amplitude range; when the ultrasonic amplitude A is within the second preset ultrasonic amplitude range, the ultrasonic amplitude A is positively correlated with the supercritical CO2 pressure P, and any value within the first preset ultrasonic amplitude range is less than any value within the second preset ultrasonic amplitude range.

[0059] The first preset ultrasonic amplitude range is 0.5-10μm, and the second preset ultrasonic amplitude range is greater than 10μm.

[0060] Moreover, when 0.5μm≤A<10μm, 8MPa<P≤15MPa, and A and P are negatively correlated; when A≥10μm, P≥8MPa, and A and P are positively correlated.

[0061] Optionally, the control module is configured to: keep the ultrasonic vibration frequency f constant, and the ultrasonic amplitude is a first preset ultrasonic amplitude A1, the supercritical CO2 pressure is a first preset pressure P1, and the first preset ultrasonic amplitude A1 is negatively correlated with the first preset pressure P1.

[0062] The first preset ultrasonic amplitude A1 satisfies the following conditions: 0.5μm ≤ A1 < 10μm, and the first preset pressure P1 satisfies the following conditions: 8MPa < P1 ≤ 15MPa. It should be noted that the values ​​of the first preset ultrasonic amplitude and the first preset pressure can be set according to actual conditions, and are not specifically limited here.

[0063] Optionally, the control module is configured to: keep the ultrasonic vibration frequency f constant, and the ultrasonic amplitude is a second preset ultrasonic amplitude A2, the supercritical CO2 pressure is a second preset pressure P2, and the second preset ultrasonic amplitude A2 is positively correlated with the first preset pressure P2.

[0064] The second preset ultrasonic amplitude A2 satisfies: A2≥10μm, and the second preset pressure P2 satisfies: P2≥8MPa. It should be noted that the values ​​of the second preset ultrasonic amplitude and the second preset pressure can be set according to actual conditions, and are not specifically limited here.

[0065] It should be noted that the value ranges of the first preset ultrasonic vibration frequency, the second preset ultrasonic vibration frequency, the first preset ultrasonic amplitude, the second preset ultrasonic amplitude, the first preset pressure, and the second preset pressure are merely illustrative examples. Specific settings can be made according to actual conditions, and no specific limitations are imposed here. Other value ranges can also be set. For example, when the ultrasonic amplitude A is kept constant, the value ranges of the ultrasonic vibration frequency f and the corresponding supercritical CO2 pressure P can be set according to Table 1; when the ultrasonic vibration frequency f is kept constant, the value ranges of the ultrasonic amplitude A and the corresponding supercritical CO2 pressure P can be set according to Table 2.

[0066] Table 1. Values ​​of ultrasonic vibration frequency f and supercritical CO2 pressure P

[0067] Serial Number Ultrasonic vibration frequency f / KHz <![CDATA[Supercritical CO2 pressure P / MPa]]> 1 16-20 12-15 2 20-30 8-12 3 30-40 8-15 4 40-50 ≥15

[0068] Table 2. Values ​​of ultrasonic amplitude A and supercritical CO2 pressure P

[0069] Serial Number Ultrasonic amplitude A / μm <![CDATA[Supercritical CO2 pressure P / MPa]]> 1 0.5-5 12-15 2 5-10 8-12 3 10-20 8-15 4 ≥20 ≥15

[0070] Optionally, the control module is also configured to: control the supercritical CO2 pressure P within a preset pressure range, control the ultrasonic amplitude A within a preset amplitude range, and control the ultrasonic vibration frequency f within a preset vibration frequency range.

[0071] For example, the preset pressure range can be greater than or equal to 8 MPa, the preset amplitude range can be greater than or equal to 0.5 micrometers, and the preset vibration frequency range can be 16-50 kHz. The lower limit of supercritical CO2 pressure is 7.31 MPa. Since flow in the pipeline will cause certain losses, this application limits the lower limit of the preset pressure range to be slightly higher than the supercritical lower limit.

[0072] In the technical solution of this embodiment, the implementation process of the supercritical CO2 and ultrasonic composite processing system is as follows: (Refer to...) Figure 1 When it is necessary to cut the workpiece, the workpiece is fixed in the processing area. The control module 20 controls the supercritical CO2 supply unit 10 to supply supercritical CO2 to the processing area, and at the same time controls the ultrasonic processing device 30 to start ultrasonic processing. The control module 20 obtains the ultrasonic amplitude from the ultrasonic processing device 30, and dynamically adjusts the supercritical CO2 pressure of the supercritical CO2 supply unit 10 according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters, so that it follows the dynamic adjustment of the ultrasonic parameters.

[0073] By combining supercritical CO2 with ultrasound, green machining of difficult-to-machine materials can be achieved. Initially, as ultrasonic parameters increase, the periodic separation of the tool and chips due to ultrasonic vibration removes most of the heat, allowing for a reduction in the amount of supercritical CO2 injected. However, as ultrasonic parameters continue to increase, the heat removed during periodic separation becomes less than the heat generated by acoustic resistance, necessitating an increase in the amount of supercritical CO2 injected. Therefore, there is a correlation between ultrasonic parameters and supercritical parameters. By rationally adjusting the supercritical parameters based on this relationship, the supercritical CO2 injection effect can be improved, ensuring machining results and quality, increasing machining efficiency and precision, and effectively reducing costs. Furthermore, using supercritical CO2 is environmentally friendly and pollution-free, providing excellent cooling and effectively reducing the temperature in the cutting zone. Ultrasonic machining also improves surface roughness and reduces machining burrs.

[0074] Figure 2 This is a schematic diagram of another supercritical CO2 and ultrasonic composite machining system provided in this application embodiment. Based on the above embodiment, the ultrasonic machining device may include a spindle 31 and an ultrasonic generator 32. The supercritical CO2 supply unit 10 is connected to the spindle 31 of the ultrasonic machining device, and supercritical CO2 is sprayed out through the cooling channel on the spindle 31 for cooling. In the technical solution of this embodiment, the implementation process of the supercritical CO2 and ultrasonic composite machining system is as follows: (Refer to...) Figure 2When the workpiece needs to be cut, it is fixed in the machining area. The control module 20 controls the supercritical CO2 supply unit 10 to supply supercritical CO2 to the machining area through the spindle 31, and simultaneously controls the ultrasonic generator 32 to provide ultrasonic signals to the transmitting unit on the spindle 31. The control module 20 obtains the ultrasonic vibration frequency from the ultrasonic generator 32 and the ultrasonic amplitude from the tool parameter monitoring unit, and dynamically adjusts the supercritical CO2 pressure of the supercritical CO2 supply unit 10 according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters, so that it follows the dynamic adjustment of the ultrasonic parameters. This helps to improve the supercritical CO2 jetting effect, thereby ensuring the machining effect and quality, improving machining efficiency and accuracy, and effectively reducing costs.

[0075] Figure 3 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in this application embodiment. Based on the above embodiment, see... Figure 3 The control module 20 may include a supercritical CO2 control module 22 and an ultrasonic processing control module 21. The supercritical CO2 control module 21 is electrically connected to the supercritical CO2 supply unit 10 to control the process parameters of the supercritical CO2. The ultrasonic processing control module 20 includes an ultrasonic control module 211, which is electrically connected to the ultrasonic processing device 20 to obtain ultrasonic parameters. The ultrasonic control module 211 is also electrically connected to the supercritical CO2 control module 22 to control the supercritical CO2 process parameters of the supercritical CO2 supply unit to dynamically adjust within a preset range according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters of the ultrasonic processing device. The supercritical CO2 process parameters include supercritical CO2 pressure, and the ultrasonic parameters include ultrasonic amplitude and ultrasonic vibration frequency.

[0076] By combining supercritical CO2 with ultrasound, green machining of difficult-to-machine materials can be achieved. Supercritical CO2 is environmentally friendly and pollution-free, providing excellent cooling and effectively reducing the temperature in the cutting zone. Ultrasonic machining further improves surface roughness and reduces burrs. Furthermore, by controlling the supercritical CO2 process parameters according to the correspondence between the supercritical CO2 process parameters and ultrasonic parameters, the jetting effect of supercritical CO2 is improved, thereby ensuring machining effect and quality, increasing machining efficiency and precision, and effectively reducing costs. Finally, automatic control of the supercritical CO2 and ultrasonic composite machining system is achieved through communication between various control modules.

[0077] The supercritical CO2 control module 22 and the ultrasonic machining control module 21 can be controllers such as microcontrollers, and the specific configuration can be determined according to actual conditions. No specific limitations are made here. The ultrasonic machining control module also includes other modules, such as the spindle control module mentioned later, which will be discussed in detail later.

[0078] Figure 4 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in this application embodiment. Figure 3 Based on the embodiments, see Figure 4 The supercritical CO2 supply unit can be connected to a third control valve 40 before outputting supercritical CO2 to the machining area. The supercritical CO2 control module can also be electrically connected to the third control valve 40 to control its opening and closing, thereby controlling the output of supercritical CO2 from the supercritical CO2 supply unit to the machining area. Furthermore, the supercritical CO2 supply unit 10 can also be connected to an ultrasonic machining device via the third control valve 40. The ultrasonic machining device sprays supercritical CO2 into the cutting area through its cooling channel, thus forming internal cooling. Alternatively, other modules can control the opening and closing of the third control valve 40, such as the spindle control module of the ultrasonic machining control system 21. When supercritical CO2 is needed, the spindle control module controls the third control valve to open, allowing the supercritical CO2 supply unit to input supercritical CO2 into the ultrasonic machining device, thereby cooling the machining area. The following description uses the example of the supercritical CO2 control module being electrically connected to the third control valve 40. The third control valve 40 can be an on / off control valve.

[0079] Figure 5 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in this application embodiment (electrical connections are shown as dashed lines to distinguish them from pipeline connections). Optionally, based on the above embodiments, refer to... Figure 5The supercritical CO2 supply unit 10 includes: a CO2 supply unit 11, a pressurization and heating unit 12, a third temperature monitoring unit 14, a first temperature monitoring unit 16, a third pressure monitoring unit 15, and a first pressure monitoring unit 17. The third temperature monitoring unit 14 and the third pressure monitoring unit 15 are respectively connected to the CO2 supply unit 11 to monitor the temperature and pressure of the CO2 in the CO2 supply unit 11. The pressurization and heating unit 12 is connected to the CO2 supply unit 11 to pressurize and heat the CO2. The first temperature monitoring unit 16 and the first pressure monitoring unit 17 are located on the pipeline connecting the pressurization and heating unit 12 to the third control valve 40 to monitor the temperature and pressure of the supercritical CO2 after pressurization and heating. The pressurization and heating unit 12, the first temperature monitoring unit 16, the first pressure monitoring unit 17, the second temperature monitoring unit 14, and the second pressure monitoring unit 15 are all electrically connected to the supercritical CO2 control module 22 to control the process parameters of the output supercritical CO2. The third temperature monitoring unit 14 and the third pressure monitoring unit 15 can be omitted.

[0080] The heating unit 12 includes a first pressurization unit 121 and a heating unit 122. A CO2 supply unit 11 provides low-temperature, low-pressure CO2 to the first pressurization unit 121. The CO2 supply unit 11 is connected to the first pressurization unit 121. The first pressurization unit 121 pressurizes the low-temperature, low-pressure CO2 to a certain pressure value (e.g., above 7.31 MPa), resulting in high-pressure CO2, which is then transported to the heating unit 122 for heating. The heating unit 122 heats the low-temperature, high-pressure CO2 to a certain temperature (e.g., above 31.7°C), thus causing the low-pressure CO2 to enter a supercritical state, resulting in supercritical CO2, which is then transported to the ultrasonic processing device 30 through the third control valve 40. Of course, provided that the supercritical CO2 output by the supercritical CO2 supply unit meets the preset requirements, the order of the first pressurization unit and the heating unit can be interchanged; that is, heating can be performed before pressurization, pressurization before heating, or both simultaneously.

[0081] The supercritical CO2 control module 22 is used to control the process parameters of the supercritical CO2 output by the supercritical CO2 supply unit 10. Specifically, the third temperature monitoring unit 14 and the third pressure monitoring unit 15 are respectively connected to the CO2 supply unit 11 to monitor the temperature and pressure of the low-temperature, low-pressure CO2 in the CO2 supply unit 11 and send the detection information to the supercritical CO2 control module 22. The first temperature monitoring unit 16 and the first pressure monitoring unit 17 are installed on the pipeline connecting the heating unit 122 and the third control valve 40 to monitor the pressure and temperature after being pressurized by the first pressurization unit 121 and heated by the heating unit 122, and send the monitoring information to the supercritical CO2 control module 22. The supercritical CO2 control module 22 is used to monitor the temperature and pressure of CO2 in the CO2 supply unit 11 in real time based on the temperature and pressure data sent by the third temperature monitoring unit 14 and the third pressure monitoring unit 15, respectively, and to monitor the temperature and pressure of the supercritical CO2 after being pressurized and heated by the first pressurization unit and the heating unit 122 in real time based on the temperature and pressure data sent by the first temperature monitoring unit 16 and the first pressure monitoring unit 17, respectively. When the pressure and temperature of the CO2 after being heated by the heating unit 122 reach the set target pressure and target temperature, the supercritical CO2 control module 22 controls the first pressurization unit 121 and the heating unit 122 to stop working.

[0082] The supercritical CO2 control module 22 is connected in sequence to the first pressurization unit 121 and the heating unit 122, and is used to control the start-up or shutdown of the first pressurization unit 121 and the heating unit 122.

[0083] Optionally, continue to refer to Figure 5 The supercritical CO2 and ultrasonic composite processing system also includes a compressed air supply unit 61, which is connected to a first pressurization unit 121 via a first control valve 64. This unit provides compressed air to the first pressurization unit 121, thereby driving the first pressurization unit 121 to pressurize the low-temperature, low-pressure CO2 output from the CO2 supply unit. The compressed air supply unit 61 is also connected to the ultrasonic processing device 30 via a second control valve 62 and a one-way valve 63. The second control valve 62 is also electrically connected to the supercritical CO2 control module 22. The ultrasonic processing control module 21 also includes a spindle control module 212, which is electrically connected to the spindle 31 of the ultrasonic processing device 30 and also electrically connected to the supercritical CO2 control module 22.

[0084] The second control valve 62 is connected to both the compressed air supply unit 61 and the one-way valve 63, with the one-way valve 63 connected to the ultrasonic processing device 30. The second control valve 62 controls whether the compressed air supply unit 61 supplies compressed air to the ultrasonic processing device 30. The one-way valve prevents supercritical CO2 from entering the compressed air pipeline. Specifically, when the machine tool needs to clean impurities inside the spindle, the spindle control module 212 sends a signal to the supercritical CO2 control module 22, which then opens the third control valve to allow compressed air to clean the spindle. After the work is completed, the third control valve closes, and the compressed air supply unit stops supplying gas to the spindle.

[0085] The supercritical CO2 control module 22 is electrically connected to the second control valve 62 and is used to control the opening or closing of the second control valve 62. Alternatively, the second control valve 62 can also be directly electrically connected to the spindle control module 212 of the ultrasonic machining control module 21, thereby directly controlling the opening or closing of the second control valve 62. Both the second control valve 62 and the first control valve 64 can be on / off control valves.

[0086] Optionally, continue to refer to Figure 5 The ultrasonic processing device 30 includes: a tool parameter monitoring unit 33, a spindle 31, an ultrasonic generator 32, a transmitting unit 35, an ultrasonic tool holder 36, and a tool 34; wherein, the tool parameter monitoring unit 33 and the ultrasonic generator 32 are electrically connected to the ultrasonic control module 211 to feed back ultrasonic parameters to the ultrasonic control module 211, and the ultrasonic control module 211 is electrically connected to the supercritical CO2 control module 22, thereby controlling the process parameters of the supercritical CO2 in the supercritical CO2 supply unit 10 according to the correspondence between the process parameters of supercritical CO2 and the ultrasonic parameters of the ultrasonic processing device. The ultrasonic parameters of the ultrasonic processing device 30 are dynamically adjusted; and the spindle control module 212 is electrically connected to the spindle 31 to control the tool change of the spindle 31. The ultrasonic generator 32 outputs voltage or current signals to the transmitting unit 35 according to the instructions of the ultrasonic control module 211. The transmitting unit 35 is fixed at the front end of the spindle 31 and forms a wireless transmission with the receiving unit of the ultrasonic tool holder 36. The tool 34 is connected to the spindle 31 through the ultrasonic tool holder 36. The spindle 31 is connected to the third control valve 40 to transport the supercritical CO2 output by the supercritical CO2 supply unit to the cutting area through the cooling channel of the spindle 31.

[0087] The third control valve 40 is connected to the spindle 31 and is used to supply supercritical CO2 to the spindle 31. The supercritical CO2 is injected to the cutting edge of the tool 34 through the internal cooling channel of the spindle 31 and the injection hole on the ultrasonic tool holder 36 to cool the cutting process.

[0088] The ultrasonic generator 32 and the tool parameter monitoring unit 33 are electrically connected to the ultrasonic control module 211 to provide feedback of ultrasonic parameters to the ultrasonic control module 211. Specifically, the tool parameter monitoring unit 33 provides feedback of ultrasonic amplitude information to the ultrasonic control module 211, and the ultrasonic generator 32 provides feedback of ultrasonic vibration frequency information to the ultrasonic control module 211.

[0089] The ultrasonic control module 211 is electrically connected to the ultrasonic generator 32 and is also used to control the adjustment of the ultrasonic parameters of the ultrasonic generator 32 to control the ultrasonic vibration frequency and other ultrasonic parameters within a preset range. The tool parameter monitoring unit 33 is electrically connected to the ultrasonic control module 211 and is also used to compare the actual ultrasonic amplitude of the tool 34 with the pre-stored tool ultrasonic amplitude. If they are inconsistent, the control outputs an adjustment signal to the ultrasonic generator 32. The ultrasonic generator 32 outputs a new voltage or current signal to the transmitting unit 33 according to the adjustment signal to adjust the actual ultrasonic amplitude of the tool 36 so that it is consistent with the pre-stored tool ultrasonic amplitude.

[0090] Optionally, continue to refer to Figure 5 The supercritical CO2 and ultrasonic composite processing system also includes a second temperature monitoring unit 91; the second temperature monitoring unit 91 is installed on the pipeline connecting the third control valve 40 and the ultrasonic processing device 30 to monitor the pipeline temperature, and the second temperature monitoring unit 91 is also electrically connected to the supercritical CO2 control module 22.

[0091] For example, refer to Figure 5 The second temperature monitoring unit 91 is installed on the pipeline connecting the third control valve 40 and the spindle 31, and is also electrically connected to the supercritical CO2 control module 22. It monitors the pipeline temperature and sends the monitored temperature to the supercritical CO2 control module 22. The advantage of installing the second temperature monitoring unit 91 between the third control valve 40 and the spindle 31 is that when using supercritical CO2, due to its excellent cooling effect, a leak would significantly reduce the temperature within the transmission channel. To avoid this affecting processing, the second temperature monitoring unit 91 is installed between the third control valve 40 and the spindle 31 to monitor the temperature in real time. If a low temperature is detected, the machine automatically shuts down and stops the supply of supercritical CO2 for troubleshooting.

[0092] Optionally, continue to refer to Figure 5 The supercritical CO2 and ultrasonic composite processing system also includes a pressure relief valve 92 and a fourth pressure monitoring unit 93. The pressure relief valve 92 and the fourth pressure monitoring unit 93 are both located on the pipeline connecting the third control valve 40 and the ultrasonic processing device 30, that is, connected to the ultrasonic processing device 30, and both are electrically connected to the supercritical CO2 control module 22. Of course, they can also be directly electrically connected to the spindle control module 212.

[0093] Because the cooling channel of the spindle contains supercritical CO2, which is under high pressure, the internal pressure of the spindle needs to be quickly relieved before tool changing. Therefore, this supercritical CO2 and ultrasonic composite machining system is also equipped with pressure relief components, including a pressure relief valve 92 and a fourth pressure monitoring unit 93. The pressure relief valve 92 and the fourth pressure monitoring unit 93 are respectively located between the third control valve 40 and the spindle 31. The fourth pressure monitoring unit 93 is used to monitor the internal pressure of the spindle 31 in real time. The tool changing operation can only be performed when the internal pressure of the spindle is zero. The function of the pressure relief valve 92 is to quickly discharge the high-pressure CO2 gas inside the spindle, so that the pressure quickly returns to zero. When tool changing is required, the spindle control module 212 sends a relevant signal to the supercritical CO2 control module 22, which controls the pressure relief valve 92 to open. When the fourth pressure monitoring unit 93 reports that the pressure is 0, the tool changing operation is then performed.

[0094] It should be noted that in this supercritical CO2 and ultrasonic composite machining system, temperature and pressure monitoring is mainly implemented by setting temperature and pressure monitoring after the pressurization unit (such as the first temperature monitoring unit and the first pressure monitoring unit), and by setting temperature monitoring before entering the spindle (such as the second temperature monitoring unit and the fourth pressure monitoring unit). There is a certain transmission distance between the supercritical CO2 supply unit and the spindle, which results in pressure and temperature losses. The pressure and temperature at the jet end of the ultrasonic tool holder 36 need to exceed certain set values ​​(e.g., pressure exceeding 7.31 MPa to ensure a supercritical state). Furthermore, when tool changing is required, pressure must be released first; tool changing can only proceed when the pressure is zero. Monitoring the temperature within the system is also crucial to prevent leakage. Therefore, pressure and temperature monitoring are necessary.

[0095] For example, the first temperature monitoring unit, the second temperature monitoring unit, and the third temperature monitoring unit can be temperature sensors. The first pressure monitoring unit, the second pressure monitoring unit, the third pressure monitoring unit, and the fourth pressure monitoring unit can be pressure sensors.

[0096] In the technical solution of this embodiment, the implementation process of the supercritical CO2 and ultrasonic composite processing system is as follows: (Refer to...) Figure 5When machining is required, the workpiece is installed in the machining position. The CO2 supply unit 11 provides low-temperature, low-pressure CO2 to the first pressurization unit 121. The compressed air supply unit 61 is connected to the first pressurization unit 121 and provides compressed air to drive the first pressurization unit 121 to pressurize it. The first pressurization unit 121 pressurizes the low-temperature, low-pressure CO2 to a certain pressure value (above 7.31 MPa) to obtain high-pressure CO2, which is then fed into the heating unit 122 for heating. The heating unit 122 heats the low-temperature, high-pressure CO2 into high-temperature, high-pressure supercritical CO2. Furthermore, a first temperature monitoring unit 16 and a first pressure monitoring unit 17 are respectively installed on the pipeline connecting the heating unit 122 and the third control valve 40 to monitor the temperature and pressure of the supercritical CO2 at the outlet of the heating unit 122 in real time, ensuring that the temperature and pressure of the CO2 reach the set temperature and pressure (the set value is slightly higher than the lower limit of the temperature and pressure in the supercritical state, and is set according to the actual situation). After being pressurized and heated, the low-temperature, low-pressure CO2 enters a supercritical state, thus obtaining supercritical CO2, which is then delivered to the spindle 31 through the third control valve 40. The spindle control module 212 controls the spindle 31 to spray the supercritical CO2 into the machining area through the spindle 31; the ultrasonic control module 211 controls the ultrasonic generator 32 to emit ultrasonic signals, thereby achieving cutting machining through the combined use of supercritical CO2 and ultrasound. Moreover, the ultrasonic control module 211 is electrically connected to the ultrasonic generator 32 and the tool parameter monitoring unit 33 to obtain the ultrasonic vibration frequency and ultrasonic amplitude. The ultrasonic control module 211 is also electrically connected to the supercritical CO2 control module 22 to control the supercritical CO2 pressure to dynamically adjust with the ultrasonic parameters according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters, thereby improving the supercritical CO2 spraying effect, ensuring machining effect and quality, improving machining efficiency and accuracy, and effectively reducing costs.

[0097] Figure 6 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application. Optionally, based on the above embodiments, refer to... Figure 6The supercritical CO2 and ultrasonic composite machining system also includes a micro-lubrication supply unit 50, which is connected to the output pipeline of the supercritical CO2 supply unit 10. The lubricating oil supplied by the micro-lubrication supply unit 50 mixes with the supercritical CO2 supplied by the supercritical CO2 supply unit 10 in the output pipeline of the supercritical CO2 supply unit 10. This mixture is then sprayed into the machining area through the internal cooling channel of the ultrasonic machining device's spindle 31, providing cooling and lubrication. Alternatively, the output pipeline of the supercritical CO2 supply unit 10 can be directly connected to an external nozzle to spray the mixture into the machining area, bypassing the internal cooling channel of the ultrasonic machining device. The control module 20 is also configured to control the oil pressure output by the micro-lubrication supply unit 50 to be greater than the supercritical CO2 pressure and to control the amount of lubricating oil output.

[0098] The control module 20 is connected to the micro-lubrication supply unit 50 and is also used to control the activation or deactivation of the micro-lubrication supply unit 50, so as to control whether the micro-lubrication supply unit 50 provides micro-lubricating oil to the output pipeline of the supercritical CO2 supply unit.

[0099] For example, a lubricating oil metering device can be installed on the output pipeline of the micro-lubrication supply unit 50 to control the amount of lubricating oil mixed with supercritical CO2. The lubricating oil metering device can be a mechanical pump, a precision metering pump, etc., and can be configured according to actual conditions; no specific limitations are made here.

[0100] Specifically, when the workpiece needs to be cut, it is fixed in the machining area. The control module 20 controls the supercritical CO2 supply unit 10 to provide supercritical CO2 and controls the micro-lubrication supply unit 50 to provide lubricating oil. The mixture of lubricating oil and supercritical CO2 is then delivered to the spindle 31. Simultaneously, the control module 20 controls the ultrasonic generator 32 to output relevant signals to the transmitting unit on the spindle 31, and dynamically adjusts the supercritical CO2 pressure of the supercritical CO2 supply unit 10 according to the feedback ultrasonic vibration frequency and amplitude, based on the correspondence between the supercritical CO2 process parameters and ultrasonic parameters. At the same time, the oil pressure output by the micro-lubrication supply unit 50 is controlled to be greater than the supercritical CO2 pressure. Therefore, by jointly controlling micro-lubrication, supercritical CO2, and ultrasound, the process parameters of supercritical CO2, ultrasonic parameters, and lubricating oil pressure can be controlled within a reasonable range, thereby improving the spraying effect of the cooling and lubricating medium, ensuring machining effect and quality, and improving machining efficiency and accuracy. Furthermore, the high-frequency vibration of ultrasound promotes better mixing of supercritical CO2 and lubricating oil, preventing excessive oil accumulation in the pipeline due to the low solubility of lubricating oil in supercritical CO2, which would otherwise lead to oil droplets ejected from the spindle nozzle. This achieves efficient internal spraying of supercritical lubricating oil and CO2. Moreover, when supercritical CO2 is ejected from the nozzle on the ultrasonic tool holder, dry ice may form at the outlet over time, affecting the spray direction and thus the cooling and lubrication effect on the tool. The high-frequency vibration of ultrasound effectively prevents dry ice accumulation and growth, ensuring the uninterrupted spray direction of supercritical CO2. In addition, using supercritical CO2 is environmentally friendly and pollution-free, provides excellent cooling, effectively reduces the temperature of the cutting zone, and, in conjunction with ultrasound, improves surface roughness, reduces burrs, lowers processing costs, and enhances processing quality and results.

[0101] Optionally, to allow the lubricating oil to dissolve better in supercritical CO2, the pressure difference between the oil pressure output by the micro-lubrication supply unit and the supercritical CO2 pressure is greater than a preset pressure difference. The preset pressure difference can be 0.5 MPa. Other values ​​are also possible and can be set according to actual conditions; no specific limitations are imposed here.

[0102] Figure 7 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application. Optionally, based on the above embodiments, refer to... Figure 7The supercritical CO2 and ultrasonic composite machining system also includes a micro-lubrication supply unit 50, which is electrically connected to the control module 20 to control the supply of lubricating oil. A supercritical CO2 supply unit 10 is connected to the output pipeline of the micro-lubrication supply unit 50, allowing the lubricating oil supplied by the micro-lubrication supply unit 50 to mix with the supercritical CO2 supplied by the supercritical CO2 supply unit 10 in the output pipeline of the micro-lubrication supply unit 50. The mixture is then sprayed into the machining area through the internal cooling channel of the spindle 31, providing cooling and lubrication. The control module 20 is also configured to control the output lubricating oil pressure of the micro-lubrication supply unit 50 to be lower than the supercritical CO2 pressure, so that the supercritical CO2 mixes better with the lubricating oil, and to control the output lubricating oil quantity.

[0103] Figure 8 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application. Optionally, based on the above embodiments, refer to... Figure 8 The supercritical CO2 and ultrasonic composite machining system also includes a micro-lubrication supply unit 50 and a mixing module 60. Both the micro-lubrication supply unit 50 and the supercritical CO2 supply unit 10 are connected to the mixing module 60. The micro-lubrication supply unit 50 is electrically connected to the control module 20 to control the output of lubricating oil. The mixing module 60 is also connected to the spindle 31. The micro-lubrication supply unit 50 is used to supply lubricating oil to the mixing module 60, and the supercritical CO2 supply unit 10 is used to supply supercritical CO2 to the mixing module 60. The mixing module 60 is used to mix the supercritical CO2 with the lubricating oil and then deliver it to the spindle 31.

[0104] The control module 20 is connected to the micro-lubrication supply unit 50 and is also used to control the activation or deactivation of the micro-lubrication supply unit 50, so as to control whether the micro-lubrication supply unit 50 provides micro-lubricating oil to the mixing module 60 and control the output of lubricating oil.

[0105] Figure 9 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in the embodiments of this application. Optionally, based on the above embodiments, refer to... Figure 9The supercritical CO2 and ultrasonic composite processing system also includes a micro-lubrication supply unit 50 and a compressed air supply unit 61. The output end of the micro-lubrication supply unit 50 is connected to the pipeline connecting the supercritical CO2 supply unit 10 and the third control valve 40, i.e., connected to the output pipeline of the supercritical CO2 supply unit 10. Since the third control valve 40 is connected to the ultrasonic processing device 30, supercritical CO2 and oil mist are finally sprayed from the ultrasonic processing device 30. The micro-lubrication supply unit 50 is also electrically connected to the supercritical CO2 control module 22. The compressed air supply unit 61 is connected not only to the supercritical CO2 supply unit 10 but also to the micro-lubrication supply unit 50 to drive the pressurization unit of the micro-lubrication supply unit 50, ensuring that the lubricating oil pressure reaches the set value.

[0106] The micro-lubrication supply unit 50 is used to supply lubricating oil to the output pipeline of the supercritical CO2 supply unit 10 so that the lubricating oil can be mixed with the supercritical CO2.

[0107] Specifically, when the system requires oil mixing, the supercritical CO2 control module 22 controls the micro-lubrication supply unit 50 to start working. When the system does not require oil mixing, the micro-lubrication supply unit 50 does not work. It should be noted that whether oil mixing is required can be set according to the actual processing requirements. For example, some products in the medical industry have special requirements that oil cannot be present.

[0108] In the technical solution of this embodiment, the implementation process of the supercritical CO2 and ultrasonic composite processing system is as follows: (Refer to...) Figure 9 When machining is required, the workpiece is mounted in the machining position. The supercritical CO2 supply unit 10 provides supercritical CO2, and the micro-lubrication supply unit 50 provides lubricating oil. In the pipeline connecting the supercritical CO2 supply unit 10 and the third control valve 40, the supercritical CO2 mixed with lubricating oil is supplied to the ultrasonic machining device 30 through the third control valve 40. The ultrasonic machining device 30 sprays the supercritical CO2 mixed with lubricating oil through its spindle cutting area, achieving cooling and lubrication, and combining this with ultrasound to perform machining on the workpiece.

[0109] Figure 10 This is a schematic diagram of another supercritical CO2 and ultrasonic composite processing system provided in this application embodiment (electrical connections are shown as dashed lines to distinguish them from pipeline connections). Optionally, based on the above embodiments, refer to... Figure 10The micro-lubrication supply unit 50 includes: a lubricating oil storage tank 51, a second pressurization unit 52, and a second pressure monitoring unit 53; the lubricating oil storage tank 51 is connected to the output pipeline of the supercritical CO2 supply unit through the second pressurization unit 52, thereby inputting lubricating oil into it; the second pressure monitoring unit 53 is connected to the output pipeline of the second pressurization unit 52 to monitor the lubricating oil pressure after the second pressurization unit 52; both the second pressurization unit 52 and the second pressure monitoring unit 53 are electrically connected to the supercritical CO2 control module 22.

[0110] The compressed air supply unit 61 is also connected to the second booster unit 52, providing compressed air to drive the second booster unit 52 to pressurize it. A control valve (not shown in the figure) is installed between the second booster unit and the compressed air supply unit. This control valve is electrically connected to the supercritical CO2 supply unit and functions the same as the second control valve; details will not be elaborated here. The lubricating oil is pressurized by the second booster unit 52. The second pressure monitoring unit 53 is connected to the second booster unit 52 and monitors the pressure of the pressurized lubricating oil. When the pressure reaches the system-set pressure value, the second booster unit 52 stops pressurizing. The lubricating oil pressurized by the second booster unit 52 is then delivered to the output pipeline of the supercritical CO2 supply unit and mixed with supercritical CO2.

[0111] When supercritical CO2 is mixed with pressurized lubricating oil (i.e., high-pressure lubricating oil), the pressure of the high-pressure lubricating oil needs to be higher than the pressure of the supercritical CO2. For example, the pressure of the lubricating oil is 0.5 MPa higher than the pressure of the supercritical CO2, which makes it easier for the lubricating oil to dissolve in the supercritical CO2.

[0112] For example, refer to Figure 10 The compressed air supply unit 61 is connected to the first booster unit 121 and the second booster unit 72 respectively, and is used to drive the first booster unit 121 and the second booster unit 72 respectively.

[0113] Optionally, continue to refer to Figure 10 The supercritical CO2 and ultrasonic composite processing system also includes a lubricating oil metering supply unit 80; one end of the lubricating oil metering supply unit 80 is connected to the second pressurization unit 72, and the other end is connected to the pipeline connecting the supercritical CO2 supply unit 10 and the third control valve 40.

[0114] When the system requires the use of lubricating oil, the amount of lubricating oil used is usually relatively small. Therefore, setting up a lubricating oil metering supply unit 80 is beneficial for accurately controlling the supply of lubricating oil, which in turn helps to ensure the efficient mixing of lubricating oil and supercritical CO2.

[0115] The lubricating oil metering unit 80 can be electrically connected to the supercritical CO2 control module 22 to limit the amount of lubricating oil mixed with supercritical CO2. The oil flow rate control range can be 0-100 ml / h or other values, which can be set according to actual conditions and are not specifically limited here.

[0116] The lubricating oil metering supply unit 80 can be a mechanical pump or a precision metering pump, and the specific configuration can be determined according to the actual situation. No specific limitations are made here.

[0117] In the technical solution of this embodiment, the implementation process of the supercritical CO2 and ultrasonic composite processing system is as follows: (Refer to...) Figure 10 When machining is required, or when supercritical CO2 needs to be mixed with a small amount of lubricating oil, the lubricating oil storage tank 51 is connected to the second pressurization unit 52, and the compressed air supply unit 61 is connected to the second pressurization unit 52 to provide compressed air to drive the second pressurization unit 52 to pressurize. The second pressurization unit 52 pressurizes the lubricating oil. The second pressure monitoring unit 53 is connected to the second pressurization unit 52 to monitor the pressure of the pressurized lubricating oil. When the pressure reaches the system-set pressure value, the second pressurization unit 52 stops pressurizing. The lubricating oil pressurized by the second pressurization unit 52 is then quantitatively delivered to the output end of the supercritical CO2 supply unit 10 via the lubricating oil metering supply unit 80 to mix with the supercritical CO2. The supercritical CO2 mixed with lubricating oil is then delivered to the spindle 31 through the third control valve 40. The spindle control module 212 controls the spindle 31 to spray supercritical CO2 mixed with lubricating oil into the machining area through the cooling channel of the spindle 31 to achieve cooling and lubrication. The ultrasonic control module 211 controls the ultrasonic generator 54 to emit ultrasonic signals, so that the supercritical CO2 mixed with a trace amount of lubricating oil and the ultrasonic waves work together to achieve cutting.

[0118] Figure 11 This is a flowchart illustrating a control method for a supercritical CO2 and ultrasonic composite processing system provided in an embodiment of this application. An embodiment of this application also provides a control method for a supercritical CO2 and ultrasonic composite processing system, see reference... Figure 11 The method includes the following steps:

[0119] S110. Based on the correspondence between the process parameters of supercritical CO2 and the ultrasonic parameters, control the process parameters of supercritical CO2 to be dynamically adjusted within a preset range in accordance with the ultrasonic parameters.

[0120] The process parameters for supercritical CO2 include supercritical CO2 pressure, and the ultrasonic parameters include ultrasonic amplitude and ultrasonic vibration frequency.

[0121] The control method for the supercritical CO2 and ultrasonic composite machining system is applied to the system. This system includes at least a supercritical CO2 supply unit, a control module, and an ultrasonic machining device. The supercritical CO2 supply unit provides supercritical CO2 to the machining area. The control module dynamically adjusts the supercritical CO2 process parameters within a preset range, based on the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters.

[0122] Furthermore, the control module can also be used to control the process parameters of the supercritical CO2 in the supercritical CO2 supply unit and the ultrasonic parameters of the ultrasonic processing device to remain stable within a preset range, as well as to control the start-up or stop of the supercritical CO2 supply unit and the ultrasonic processing device.

[0123] The technical solution of this embodiment provides a control method for a supercritical CO2 and ultrasonic composite machining system. This control method includes: maintaining stable process parameters of the supercritical CO2 supply unit and ultrasonic parameters of the ultrasonic machining device; and dynamically adjusting the supercritical CO2 process parameters within a preset range, following the ultrasonic parameters, based on the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters. The supercritical CO2 process parameters include supercritical CO2 pressure, and the ultrasonic parameters include ultrasonic amplitude and ultrasonic vibration frequency. Therefore, by combining supercritical CO2 and ultrasound, green cutting processing of difficult-to-machine materials can be achieved. Furthermore, by controlling the supercritical CO2 process parameters to dynamically adjust according to the correspondence between the supercritical CO2 process parameters and the ultrasonic parameters, the supercritical CO2 process parameters are kept within a reasonable range, thereby ensuring processing effect and quality, improving processing efficiency and accuracy, and effectively reducing costs. In addition, by using supercritical CO2 internal injection, it is green, environmentally friendly and pollution-free, with good cooling effect, which can effectively reduce the temperature of the cutting zone. Furthermore, ultrasonic processing can also improve the surface roughness, reduce burr problems, and reduce processing costs.

[0124] Figure 12 This is a schematic diagram of the overall process of a supercritical CO2 and ultrasonic composite processing system provided in an embodiment of this application. For example, refer to... Figure 12Under normal processing conditions (automatic mode, program loading upon startup), the sequence of actions of the machining tool is as follows: First, the supercritical CO2 supply unit is started, allowing the pressurized heating system (i.e., the first pressurization unit and the heating unit) to pressurize and heat to a reasonable preset value. The workpiece to be processed is fixed on the machine tool's operating table, and the machine tool is started to prepare for processing. The depressurization system (i.e., the second pressure monitoring unit) monitors the internal pressure of the spindle. When the pressure signal is zero, the next instruction can be executed. If the program has a tool change instruction, the tool change action is executed. After the tool is ready, (if the program has an instruction) the ultrasonic control module controls the completion of the amplitude adjustment action. Subsequently, the supercritical CO2 control module controls the supercritical CO2 supply unit to spray supercritical CO2 (the supercritical CO2 control module controls the third control valve to open). Then, processing is carried out according to the part processing program. During the processing, the second temperature monitoring unit can monitor the system temperature in real time. During processing, the ultrasonic control module collects ultrasonic vibration frequency data from the ultrasonic generator and ultrasonic amplitude monitoring data from the tool parameter monitoring unit. The supercritical CO2 control module monitors the supercritical CO2 pressure. The ultrasonic control module is electrically connected to the supercritical CO2 control module. Based on the acquired ultrasonic vibration frequency and amplitude, the ultrasonic control module continuously sends commands to the supercritical CO2 control module to adjust the supercritical CO2 pressure, i.e., controlling the process parameters of supercritical CO2 in the supercritical CO2 supply unit to dynamically adjust within a preset range according to the ultrasonic parameters of the ultrasonic processing device. This adjustment is continuously cyclical during the processing. When the current tool's processing step is completed and a tool change is required for subsequent processing, the ultrasonic control module controls the ultrasonic generator to shut down and simultaneously communicates with the supercritical CO2 control module to control the supercritical CO2 supply unit to stop injecting supercritical CO2. It also opens the pressure relief system (i.e., the fourth pressure monitoring unit and pressure relief valve) until the internal pressure of the spindle is zero. Then, a tool change is performed for subsequent processing until the part is finished.

[0125] This application also provides a machine tool, which includes the supercritical CO2 and ultrasonic composite machining system provided in any embodiment of this application.

[0126] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0127] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A supercritical The ultrasonic composite processing system is characterized by, include: supercritical The system comprises a supply unit, a control module, and an ultrasonic processing device; wherein the control module is connected to the supercritical fluid. The supply unit is electrically connected, and the control module is also electrically connected to the ultrasonic processing device; The control module is also configured to: based on supercritical... The correspondence between process parameters and ultrasonic parameters is used to control the supercritical... The process parameters are dynamically adjusted within a preset range following the ultrasonic parameters, and the supercritical... The process parameters include supercritical Pressure P, the ultrasonic parameters include the ultrasonic amplitude A and ultrasonic vibration frequency f of the ultrasonic processing device; Among them, the supercritical The relationship between pressure P and ultrasonic vibration frequency f is as follows: when the ultrasonic vibration frequency f is within the first preset ultrasonic vibration frequency range, the ultrasonic vibration frequency f and the supercritical... Pressure P is negatively correlated. When the ultrasonic vibration frequency f is within the second preset ultrasonic vibration frequency range, the ultrasonic vibration frequency f is related to the supercritical... The pressure P is positively correlated, and any value within the first preset ultrasonic vibration frequency range is less than any value within the second preset ultrasonic vibration frequency range; or; The supercritical The relationship between pressure P and ultrasonic amplitude A is as follows: when ultrasonic amplitude A is within the first preset ultrasonic amplitude range, ultrasonic amplitude A is related to supercritical... Pressure P is negatively correlated. When the ultrasonic amplitude A is within the second preset ultrasonic amplitude range, the ultrasonic amplitude A is related to the supercritical... The pressure P is positively correlated, and any value within the first preset ultrasonic amplitude range is less than any value within the second preset ultrasonic amplitude range.

2. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, The first preset ultrasonic vibration frequency range is 16KHz ≤ f < 30KHz, and the second preset ultrasonic vibration frequency range is 30KHz ≤ f ≤ 50KHz.

3. The supercritical system according to claim 2 The ultrasonic composite processing system is characterized by, When 16kHz ≤ f < 30kHz, 8MPa < P ≤ 15MPa, and f is negatively correlated with P; when 30kHz ≤ f ≤ 50kHz, P ≥ 8MPa, and f is positively correlated with P.

4. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, The first preset ultrasonic amplitude range is 0.5μm≤ A<10μm, and the second preset ultrasonic amplitude range is A≥10μm.

5. The supercritical system according to claim 4 The ultrasonic composite processing system is characterized by, When 0.5μm≤A<10μm, 8MPa<P≤15MPa, and A and P are negatively correlated; when A≥10μm, P≥8MPa, and A and P are positively correlated.

6. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, The control module is configured to: control the supercritical... The pressure is within a preset pressure range, the ultrasonic amplitude is controlled within a preset ultrasonic amplitude range, and the ultrasonic vibration frequency is controlled within a preset ultrasonic vibration frequency range. The preset pressure range is P≥8MPa, the preset ultrasonic amplitude range is A≥0.5μm, and the preset ultrasonic vibration frequency is 16KHz≤f≤50KHz.

7. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, It also includes a micro-lubrication supply unit, which is connected to the supercritical fluid. On the output pipeline of the supply unit, the micro-lubrication supply unit is also electrically connected to the control module; The control module is also configured to control the pressure of the lubricating oil output by the micro-lubrication supply unit to be greater than the supercritical pressure. pressure.

8. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, It also includes a micro-lubrication supply unit and a mixing module, the micro-lubrication supply unit and the supercritical All supply units are connected to the hybrid module, and the micro-lubrication supply unit is also electrically connected to the control module.

9. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, It also includes a micro-lubrication supply unit, the supercritical The supply unit is connected to the output pipeline of the micro-lubrication supply unit, and the micro-lubrication supply unit is also electrically connected to the control module; The control module is also configured to: control the lubricating oil pressure output by the micro-lubrication supply unit to be less than the supercritical pressure. pressure.

10. The supercritical system according to claim 1 The ultrasonic composite processing system is characterized by, The supercritical The end of the output pipe of the supply unit is connected to the ultrasonic processing device.

11. A method for use in supercritical fluid as described in any one of claims 1-10 The control method for the ultrasonic composite processing system is characterized by, include: According to supercritical The correspondence between process parameters and ultrasonic parameters is used to control the supercritical... The process parameters are dynamically adjusted within a preset range following the ultrasonic parameters, and the supercritical... The process parameters include supercritical Pressure, the ultrasonic parameters include ultrasonic amplitude and ultrasonic vibration frequency.

12. A machine tool, characterized in that, Including supercritical as described in any one of claims 1-10 And ultrasonic composite processing system.

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