An ultrasonic machining interface region turbulent flow enhanced heat exchange cooling method and system
By spraying dry ice microparticles and cutting fluid during ultrasonic machining, the sublimation of the dry ice microparticles creates turbulence at the tool-material interface, solving the problem of unsatisfactory cooling effect of traditional cooling methods and achieving rapid heat exchange and lubrication in ultrasonic machining.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
- Filing Date
- 2023-10-25
- Publication Date
- 2026-05-12
AI Technical Summary
Traditional cooling methods used in ultrasonic vibration cutting are not ideal. The cutting fluid rapidly vaporizes at high temperatures to form a vapor film, which hinders the entry of new fluid and results in poor cooling performance.
When the tool separates from the workpiece, dry ice microparticles and cutting fluid are sprayed. The sublimation of the dry ice microparticles creates instantaneous fluid turbulence inside and outside the interface cavity. Combined with ultrasonic vibration, multiple cooling mechanisms are formed, including ultrasonic cavitation jet, bubble bursting turbulence, and dry ice sublimation heat absorption, to achieve rapid heat exchange.
Through multiple cooling mechanisms, the cooling and lubrication effect during ultrasonic processing is significantly improved, ensuring processing quality and efficiency and avoiding thermal damage.
Smart Images
Figure CN117340677B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ultrasonic vibration processing technology, and in particular to a method and system for turbulent heat transfer and cooling in the interface region of ultrasonic processing. Background Technology
[0002] In the development of major national equipment in the aerospace field, various difficult-to-machine materials are constantly emerging, including ceramic matrix composites, polymer matrix composites, metal matrix composites, and special metal materials. The manufacturing process involves the accumulation of force and heat, rapid tool wear, difficulty in quality assurance, and low machining efficiency. Manufacturing defects or the physicochemical properties of the process pose numerous challenges to equipment manufacturing and service performance. Ultrasonic vibration cutting is an effective means to address the manufacturing challenges of difficult-to-machine materials. However, a large amount of cutting heat is generated in the cutting zone during the cutting process. To avoid thermal damage to the workpiece and to ensure machining quality and efficiency, the machining zone must be lubricated and cooled to reduce heat generation and remove the generated heat promptly. Traditional cooling methods allow only a small amount of cutting fluid to enter the cutting zone and truly provide lubrication and cooling. Moreover, this small amount of cutting fluid that enters the cutting zone quickly vaporizes into a "vapor film" upon heating. The formation of this vapor film hinders the entry of new cutting fluid into the high-temperature cutting zone, resulting in unsatisfactory cooling effects. Summary of the Invention
[0003] The purpose of this invention is to provide a method and system for turbulent heat transfer and cooling in the interface region of ultrasonic machining, which solves the problem of unsatisfactory cooling effect of traditional cooling methods in existing ultrasonic vibration cutting.
[0004] To achieve the above objectives, in a first aspect, the present invention provides a method for turbulent heat transfer and cooling in the interface region of ultrasonic machining. During the machining process, the ultrasonic amplitude satisfies the following: as the amplitude changes periodically, there exists a state of separation between the tool and the material to be machined. When the tool and the material to be machined separate, an interface cavity is formed between the tool and the material to be machined.
[0005] When dry ice microparticles and cutting fluid are sprayed, at least some of the dry ice microparticles and cutting fluid enter the interface cavity when the tool separates from the workpiece interface. Under the ultrasonic vibration of the tool and the sublimation of the dry ice microparticles, the mixture forms a cavitation jet and instantaneous fluid turbulence in the interface cavity. The mixture of cutting fluid and dry ice microparticles that do not enter the interface cavity forms instantaneous fluid turbulence outside the interface cavity under the sublimation of the dry ice microparticles. When the tool contacts the workpiece interface, the mixture of cutting fluid and dry ice microparticles forms instantaneous fluid turbulence around the cutting area under the sublimation of the dry ice microparticles.
[0006] Optionally, the cutting fluid is injected under high pressure, with a injection pressure range of 5-10 MPa.
[0007] Optionally, the cutting fluid is micro-injected, with a flow rate ranging from 0.02 mL / min to 50 mL / min.
[0008] Optionally, the cutting fluid is deionized water.
[0009] Secondly, the present invention also provides another ultrasonic machining interface region turbulence enhanced heat transfer cooling method. During the machining process, the ultrasonic amplitude satisfies the following: as the amplitude changes periodically, there is a state of separation between the tool and the material to be machined. When the tool and the material to be machined separate, an interface cavity is formed between the tool and the material to be machined.
[0010] When dry ice microparticles are sprayed and the interface between the tool and the workpiece is separated, at least some of the dry ice microparticles enter the interface cavity. Under the sublimation effect of the dry ice microparticles, the dry ice microparticles that have entered the interface cavity and those that have not entered the interface cavity form instantaneous gas turbulence inside and outside the interface cavity, respectively. When the tool contacts the interface of the workpiece, under the sublimation effect of the dry ice microparticles, instantaneous gas turbulence is formed around the cutting area.
[0011] Optionally, based on either the first or the second aspect, the dry ice particles are ejected in a planar manner to form a dry ice particle plane;
[0012] The plane formed by the axis of the tool and the direction of tool movement is called the tool plane;
[0013] The plane of the dry ice particles is parallel to the plane of the cutting tool.
[0014] Thirdly, the present invention also provides a turbulence-enhanced heat transfer and cooling system for the interface region of ultrasonic machining, including a dry ice injector, a cutting fluid injection unit, a dry ice injection control unit, a cutting fluid injection control unit, and a nozzle;
[0015] The liquid carbon dioxide and air source are connected to the dry ice injector through the dry ice injection control unit, which includes a temperature control module and a flow valve for adjusting the temperature and flow rate of the liquid carbon dioxide and air.
[0016] The cutting fluid is connected to the cutting fluid injection unit through the cutting fluid control unit. The cutting fluid injection control unit includes a flow regulating unit for regulating the flow rate of the cutting fluid.
[0017] The dry ice injector and the cutting fluid injection unit are connected to the nozzle and are used to spray dry ice particles and cutting fluid into the cutting area.
[0018] Optionally, the flow regulating unit is a flow regulating valve, and the cutting fluid is connected to the cutting fluid injection unit through the flow regulating valve.
[0019] Optionally, the flow regulating unit is a high-pressure pump and a micro pump, and by switching, the cutting fluid can be delivered to the cutting fluid injection unit via one of the high-pressure pump and the micro pump.
[0020] The above-described technical solution of the present invention has the following advantages:
[0021] The ultrasonic machining interface region turbulence-enhanced heat transfer cooling method provided by this invention addresses the separation state between the tool and the workpiece interface during machining, which occurs due to changes in amplitude and period. When the tool and workpiece interface separate, an interface cavity is formed between them. By spraying dry ice particles and cutting fluid, at least some of the dry ice particles and cutting fluid enter the interface cavity during separation. This cooling method, based on ultrasonic frequency separation of the tool and workpiece interface, can create multiple cutting cooling mechanisms by spraying cutting fluid and dry ice particles onto the tool and workpiece interface: ultrasonic cavitation jets accelerate fluid movement at the ultrasonic machining interface; turbulent flow from the mixing of dry ice particles and cutting fluid within and outside the interface cavity accelerates heat transfer between the interface cavity and the material interface, while simultaneously accelerating heat transfer between the interface cavity and the outside; dry ice and cutting fluid mix, and dry ice sublimation lowers the cutting fluid temperature; dry ice sublimation expands and absorbs heat for cooling; and rapid expansion and rupture of sublimated dry ice creates instantaneous gas turbulence that accelerates fluid movement. Through multiple cooling mechanisms and accelerated solid-liquid flow in the cutting area, rapid heat exchange and cooling / lubrication effects are achieved in the cutting area during ultrasonic vibration cutting. Attached Figure Description
[0022] The accompanying drawings are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not be consistent with the actual product.
[0023] Figure 1 This is a schematic diagram of the wave-like cutting process of the ultrasonic vibration cutting system in Embodiment 1 of the present invention;
[0024] Figure 2 This is a schematic diagram of the turbulent heat transfer and cooling process in the ultrasonic processing interface region in Embodiment 1 of the present invention;
[0025] Figure 3 This is a schematic diagram of the turbulent enhanced heat transfer cooling process in the ultrasonic processing interface region according to Embodiment 1 of the present invention.
[0026] Figure 4 This is a schematic diagram illustrating the relationship between the plane of dry ice particles and the plane of the cutting tool in Embodiment 1 of the present invention;
[0027] Figure 5 yes Figure 4 A top-down view.
[0028] In the picture:
[0029] 100: Knives;
[0030] 200: Materials to be processed;
[0031] 300: Cutting fluid;
[0032] 400: Dry ice microparticles;
[0033] 500: Interface cavity;
[0034] 600: Turbulence;
[0035] 700: Nozzle;
[0036] 800: Dry ice particle plane;
[0037] 900: Tool plane. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0039] Example 1
[0040] See Figures 1-3 As shown in the embodiment of the present invention, the ultrasonic machining interface region turbulence-enhanced heat transfer cooling method is used in an ultrasonic vibration cutting system. During the machining process, the ultrasonic amplitude satisfies the following condition: as the amplitude changes periodically, the interface between the tool 100 and the material to be machined 200 is in a state of separation. When the interface between the tool 100 and the material to be machined 200 separates, an interface cavity 500 is formed between the interface between the tool 100 and the material to be machined 200. Figure 1 The dashed line represents the tool at different positions during vibration; h(t) is the dynamic cutting thickness; z(t) is the current cutting trajectory; z(tT) is the cutting trajectory of the tool in the previous revolution; Asin(2kπt) is the tool vibration trajectory. Where A is the amplitude; k is the frequency; t is the time; and T is the tool's revolution per cycle. Figure 2 The dashed lines of the same shape near the cutting tool indicate the tool at different positions during vibration; when the tool is in contact with the workpiece, the area between the two vertical dashed lines indicates the machining area; when the tool is separated from the workpiece, the area between the two vertical dashed lines indicates the interface cavity; the irregular lumps between the tool and the workpiece indicate the bursting of bubbles in the mixture of dry ice particles and cutting fluid.
[0041] See Figure 2 and Figure 3As shown, when the interface between the cutting tool 100 and the workpiece 200 separates, dry ice particles 400 and cutting fluid 300 are sprayed. At least some of the dry ice particles 400 and cutting fluid 300 enter the interface cavity 500. Under the ultrasonic vibration of the cutting tool 100 and the sublimation of the dry ice particles, the mixture of cutting fluid and dry ice particles forms a cavitation jet and instantaneous fluid turbulence, accelerating the fluid movement inside the interface cavity 500. The mixture of cutting fluid and dry ice particles that does not enter the interface cavity 500 forms instantaneous fluid turbulence outside the interface cavity 500 under the sublimation of the dry ice particles. When the cutting tool 100 contacts the interface of the workpiece 200, the mixture of cutting fluid and dry ice particles forms instantaneous fluid turbulence around the cutting area under the sublimation of the dry ice particles. It should be noted that under ultrasonic machining conditions, when cutting fluid is present in the interface cavity, the fluid inside the interface cavity is mainly liquid.
[0042] This cooling method is based on ultrasonic separation at the tool-material interface. By spraying cutting fluid and dry ice particles onto the tool-material interface, multiple cutting cooling mechanisms are formed: ultrasonic cavitation jets at the ultrasonic machining interface accelerate fluid movement; inside and outside the interface cavity, dry ice particles mix with cutting fluid, causing bubble bursts and turbulence, accelerating heat exchange between the interface cavity and the material interface, and simultaneously accelerating heat exchange between the interface cavity and the outside; dry ice mixes with cutting fluid, and dry ice sublimation lowers the cutting fluid temperature; dry ice sublimation expands and absorbs heat for cooling; rapid expansion and bursting of dry ice sublimation creates instantaneous gas turbulence, accelerating fluid movement. Through multiple cooling mechanisms and accelerated solid-liquid flow in the cutting area, rapid heat exchange and cooling / lubrication effects are achieved in the cutting area during ultrasonic vibration cutting.
[0043] In some preferred embodiments, see Figure 4 and Figure 5 As shown, dry ice particles are ejected in a planar manner through nozzle 700, forming a dry ice particle plane 800. The plane formed by the axis of the cutter 100 and the direction of movement of the cutter 100 is the cutter plane 900. The dry ice particle plane 800 is parallel to the cutter plane 900. Under the action of the rotation of the cutter 100, the dry ice particles can more easily enter the cutting area, thereby further improving the heat exchange effect.
[0044] It should be noted that the dry ice particles are ejected in a planar shape through nozzle 700 using the existing nozzle structure, which will not be elaborated here.
[0045] Depending on the processing materials or processing scenarios, dry ice microparticles and cutting fluid are combined in different ways. In some implementations, the cutting fluid is injected at high pressure, with a pressure range of 5-10 MPa. In one example, this is achieved by pressurizing with a high-pressure pump. Under ultrasonic machining conditions, high-pressure cutting fluid is injected into the cutting zone. Dry ice microparticles mix with the cutting fluid, rapidly sublimating and lowering the cutting fluid temperature. Under ultrasonic interface separation conditions, the cutting fluid enters the separation interface, achieving cooling.
[0046] In other embodiments, the cutting fluid is micro-injected at a flow rate ranging from 0.02 mL / min to 50 mL / min. In some specific examples, this is achieved using a flow valve or a micro-pump. During ultrasonic machining, dry ice microparticles are mixed with a micro-sized cutting fluid and separated at the ultrasonic interface. The micron-sized dry ice microparticles are then sprayed into the cutting zone and surrounding area. The dry ice sublimates and expands in the dry ice-micro-cutting fluid mixture, creating instantaneous turbulence around the cutting zone. This accelerates heat exchange between the cutting zone and the surrounding environment, speeds up the cutting process, and improves cutting quality.
[0047] In some implementations, the cutting fluid is deionized water, which can effectively reduce pollution.
[0048] The above embodiments can use a dry ice injector to spray dry ice particles and a cutting fluid injection unit to spray cutting fluid. More specifically, the dry ice injector and the cutting fluid injection unit are connected to a nozzle, through which dry ice particles and cutting fluid are sprayed into the cutting area.
[0049] This embodiment also provides a turbulence-enhanced heat transfer and cooling system for the interface region of ultrasonic machining, including a dry ice injector, a cutting fluid injection unit, a dry ice injection control unit, a cutting fluid injection control unit, and a nozzle.
[0050] In this embodiment, dry ice microparticles are prepared using liquid carbon dioxide and air. The liquid carbon dioxide and air sources are connected to the dry ice injector via a dry ice injection control unit. This control unit includes a temperature control module and a flow valve, used to adjust the temperature and flow rate of the liquid carbon dioxide and the air required for preparing the dry ice microparticles, thereby achieving the generation and flow control of the dry ice microparticles. In a preferred embodiment, the air is filtered, dried, and its pressure is regulated. In an example embodiment, the air source pressure is 0.6-0.8 MPa, and the liquid carbon dioxide pressure is not less than 6 MPa. Under ultrasonic processing conditions, the high-pressure liquid carbon dioxide is ejected through a throttling expansion effect, forming dry ice microparticles (solid carbon dioxide) at the nozzle outlet according to the Joule-Thomson effect. These microparticles are then sprayed onto the heat exchange surface. Under ultrasonic interface separation conditions, the dry ice microparticles approach the cutting interface, and on the heat source surface, the dry ice sublimates, carrying away surface heat, thereby achieving cooling.
[0051] It should be noted that the preparation of dry ice microparticles using liquid carbon dioxide and air is an existing technology and will not be elaborated upon here.
[0052] The cutting fluid is connected to the cutting fluid injection unit via a cutting fluid control unit. The cutting fluid injection control unit includes a flow regulating unit for regulating the flow rate of the cutting fluid. The dry ice injector and the cutting fluid injection unit are connected to a nozzle for spraying dry ice particles and cutting fluid into the cutting area.
[0053] In some embodiments, the flow regulation unit is a flow regulating valve, through which the cutting fluid is connected to the cutting fluid injection unit. In other embodiments, the flow regulation unit is a high-pressure pump and a micro pump, which can be switched to deliver the cutting fluid to the cutting fluid injection unit. The high-pressure pump has a pressure range of 5-10 MPa, and the micro pump has a flow rate range of 0.02 mL / min-50 mL / min.
[0054] The working process of this ultrasonic machining interface region turbulence-enhanced heat transfer and cooling system is as follows:
[0055] Step 1: With the machining center in a stopped state, connect all pipelines, adjust the nozzle position, align it with the cutting area, and fix the ultrasonic processing equipment to the machining center;
[0056] Step 2: Adjust the liquid carbon dioxide pressure to be no less than 6 MPa, and adjust the flow rate of the micro pump to be between 0.02 mL / min and 50 mL / min;
[0057] Step 3: Turn on the cooling system and adjust the dry ice output;
[0058] Step 4: Turn on the ultrasonic processing equipment and adjust the ultrasonic power to make the amplitude appropriate. For hard and brittle materials or fine machining, the amplitude can be appropriately reduced, while for plastic materials or rough machining, the amplitude can be appropriately increased.
[0059] Step 5: After processing is complete, first turn off the ultrasonic processing equipment, and then turn off the cooling system.
[0060] Ultrasonic vibration cutting systems are existing technology, and in this embodiment, they are used to provide ultrasonic assistance to improve cooling efficiency. In one example, the ultrasonic excitation section includes an ultrasonic power supply primary, an ultrasonic transducer, and an ultrasonic power source. The ultrasonic power supply primary is connected to the machine tool spindle, the ultrasonic transducer is connected to the spindle, the ultrasonic power source is connected to the ultrasonic power supply primary, and the cutting tool is connected to the end of the ultrasonic transducer. The direction of ultrasonic vibration is parallel to the machine tool spindle axis. The ultrasonic power supply primary and the ultrasonic transducer are powered by induction. The ultrasonic power source adjusts the amplitude by regulating the power, ensuring that the ultrasonic amplitude during machining satisfies the condition of separation between the cutting tool and the material interface.
[0061] When the cutting fluid is deionized water, deionized water can be supplied to the cutting fluid injection unit. Alternatively, ordinary water can be deionized before being supplied to the cutting fluid injection unit.
[0062] The aforementioned ultrasonic machining interface region turbulence-enhanced heat transfer and cooling system can provide equipment support for the ultrasonic machining interface region turbulence-enhanced heat transfer and cooling method, and realize rapid heat exchange and cooling and lubrication effects in the cutting area during ultrasonic vibration cutting.
[0063] Example 2
[0064] The ultrasonic processing interface region turbulence-enhanced heat transfer and cooling method provided in this embodiment is basically the same as that in embodiment one. The similarities will not be repeated here. The difference is that the cooling method only sprays dry ice particles. The dry ice particles sublimate, expand in volume, absorb heat and cool, and form instantaneous gas turbulence, which accelerates gas flow and enhances the heat transfer effect.
[0065] The cooling method of this embodiment can be implemented using the ultrasonic machining interface region turbulence-enhanced heat transfer cooling system in Embodiment 1 (only the dry ice spraying part needs to work, and the cutting fluid spraying part does not need to work). Of course, the cutting fluid spraying part can also be removed from the ultrasonic machining interface region turbulence-enhanced heat transfer cooling system in Embodiment 1, and only the dry ice spraying part can be retained to realize the ultrasonic machining interface region turbulence-enhanced heat transfer cooling method of this embodiment.
[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution, and in the absence of conflict between solutions, the various technical features mentioned in each embodiment can be combined in any way to form other implementation methods that can be understood by those skilled in the art.
[0067] Furthermore, without departing from the scope of the present invention, modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for enhancing heat transfer and cooling through turbulence in the interface region of ultrasonic processing, characterized in that: During the processing, the ultrasonic amplitude satisfies the following: as the amplitude changes periodically, there is a state of separation between the tool and the material to be processed. When the tool and the material to be processed separate, an interface cavity is formed between the tool and the material to be processed. When dry ice microparticles and cutting fluid are sprayed, at least a portion of the dry ice microparticles and cutting fluid enter the interface cavity when the tool separates from the workpiece interface. Under the ultrasonic vibration of the tool and the sublimation of the dry ice microparticles, the mixture of cutting fluid and dry ice microparticles forms a cavitation jet and instantaneous fluid turbulence within the interface cavity. The remaining portion of the mixture of cutting fluid and dry ice microparticles that does not enter the interface cavity forms instantaneous fluid turbulence outside the interface cavity under the sublimation of the dry ice microparticles. When the tool contacts the workpiece interface, the mixture of cutting fluid and dry ice microparticles forms instantaneous fluid turbulence around the cutting area under the sublimation of the dry ice microparticles. The dry ice particles are ejected in a planar manner, forming a dry ice particle plane. The plane formed by the axis of the cutting tool and the direction of movement of the cutting tool is the cutting tool plane; The plane of the dry ice particles is parallel to the plane of the cutting tool.
2. The ultrasonic processing interface region turbulence-enhanced heat transfer and cooling method according to claim 1, characterized in that: The cutting fluid is injected at high pressure, with a injection pressure range of 5-10 MPa.
3. The ultrasonic processing interface region turbulence-enhanced heat transfer and cooling method according to claim 1, characterized in that: The cutting fluid micro-injection has a flow rate range of 0.02 mL / min to 50 mL / min.
4. The ultrasonic processing interface region turbulence-enhanced heat transfer and cooling method according to claim 1, characterized in that: The cutting fluid is deionized water.
5. A turbulence-enhanced heat transfer and cooling system for the interface region of ultrasonic machining, used to implement the turbulence-enhanced heat transfer and cooling method for the interface region of ultrasonic machining as described in claim 1, characterized in that: It includes a dry ice injector, a cutting fluid injection unit, a dry ice injection control unit, a cutting fluid injection control unit, and a nozzle; Liquid carbon dioxide and air sources are connected to the dry ice injector through the dry ice injection control unit. The dry ice injection control unit includes a temperature control module and a flow valve for adjusting the temperature and flow rate of the liquid carbon dioxide and air. The cutting fluid is connected to the cutting fluid injection unit via a cutting fluid control unit, and the cutting fluid injection control unit includes a flow regulating unit for regulating the flow rate of the cutting fluid; The dry ice injector and the cutting fluid injection unit are connected to the nozzle and are used to spray dry ice particles and cutting fluid into the cutting area.
6. The ultrasonic processing interface region turbulence-enhanced heat transfer and cooling system according to claim 5, characterized in that: The flow regulation unit is a flow regulation valve, and the cutting fluid is connected to the cutting fluid injection unit through the flow regulation valve.
7. The ultrasonic processing interface region turbulence-enhanced heat transfer and cooling system according to claim 5, characterized in that: The flow regulation unit consists of a high-pressure pump and a micro pump. By switching between them, the cutting fluid can be delivered to the cutting fluid injection unit via one of the high-pressure pump and the micro pump.