Ultrasonic enhanced hot melting drilling tool for ice layer drilling and ice melting method of ultrasonic enhanced hot melting drilling tool
By combining the ultrasonic vibration of the ultrasonic-enhanced thermal fusion drill bit with the synergistic effect of the thermal fusion module, the problems of low efficiency, high energy consumption, and stuck drill in polar ice drilling technology have been solved, achieving a more efficient and safer ice drilling effect.
Patent Information
- Application Number
- CN202512006139.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-02-06
AI Technical Summary
Existing thermal drilling technology has problems such as low thermal efficiency, unstable melting interface, high energy consumption, and difficulty in destroying the microstructure of ice layers in polar ice drilling. It is particularly ineffective in high-density ice and sandy ice, and there is a risk of drill bit jamming.
An ultrasonically enhanced thermal melting drill is used, which generates axial ultrasonic vibration through a piezoelectric drive module and works in synergy with the thermal melting module. The ultrasonic vibration improves heat transfer, breaks down ice crystal structure, and accelerates melting through cavitation effect. Combined with intermittent pulse working mode and composite vibration unblocking, a more efficient and stable ice melting process is achieved.
It significantly improves ice melting efficiency, reduces energy consumption, reduces the risk of drill bit jamming, and improves drilling safety and continuity. It is suitable for ice drilling in confined environments and low-temperature conditions.
Smart Images
Figure CN121473684A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of ice layer drilling, and particularly relates to an ultrasonic enhanced thermal melting drilling tool for ice layer drilling and an ice melting method thereof. BACKGROUND
[0002] In the fields of polar scientific exploration, mountain glacier monitoring, sea ice engineering, and planetary ice shell (such as Europa and Enceladus) exploration, it is of great significance to quickly penetrate, sample, and deploy sensors in ice layers.
[0003] Thermal melting drilling technology, which melts ice layers by heating drill bits to form a forward channel, is widely used in polar ice cap drilling; however, pure thermal melting technology has the following defects: (1) Low thermal efficiency: ice layers have high latent heat, and the melting speed of pure heating is limited. In addition, the temperature gradient of ice layers is large, which makes the melting interface unstable, resulting in serious energy loss.
[0004] (2) Channel collapse and refreezing problem: the melted water may rise along the drill hole and quickly refreeze, increasing the risk of drill tool jamming.
[0005] (3) High energy consumption: a large amount of electrical energy is usually required to maintain the melting interface, which is not conducive to the use of lightweight mobile platforms or interstellar probes.
[0006] (4) Cannot effectively destroy the microstructure of ice layers: it is difficult to handle high-density ice, sandy ice, or solid inclusions. SUMMARY
[0007] The purpose of the present application is to provide an ultrasonic enhanced thermal melting drilling tool for ice layer drilling and an ice melting method thereof. The ultrasonic enhanced thermal melting drilling tool is a new drilling tool structure that cooperates with ultrasonic vibration. It improves heat transfer, destroys ice crystal structure, and accelerates melting by using cavitation effect, thereby achieving higher drilling speed, lower energy consumption, and more stable melting interface.
[0008] To achieve the above purpose, the present application adopts the following technical solutions: According to a first aspect of the present application, an ultrasonic enhanced thermal melting drilling tool for ice layer drilling is provided, comprising a piezoelectric driving module and a thermal melting module; the piezoelectric driving module is used to generate and transmit axial ultrasonic vibration; the thermal melting module is used to heat and melt ice layers; The vibration output end of the piezoelectric driving module is connected with the drill bit base body of the thermal melting module, so that the ultrasonic vibration can be transmitted to the front end of the drill bit base body and cooperates with the heat generated by the thermal melting module to accelerate the melting of ice layers and inhibit the refreezing of melted water; The driving frequency range of the piezoelectric driving module is 20 kHz to 40 kHz, the piezoelectric driving module comprises a piezoelectric cabin shell, a piezoelectric ceramic stack arranged in the piezoelectric cabin shell, a pre-tightening structure for applying an axial pre-tightening force to the piezoelectric ceramic stack, and a front cover body; the piezoelectric ceramic stack is composed of a plurality of piezoelectric ceramic sheets and positive and negative conductive sheets alternately arranged between adjacent piezoelectric ceramic sheets; the front cover body is connected to the front end of the piezoelectric ceramic stack, and the piezoelectric cabin shell is fixed to the plane where the vibration displacement of the front cover body is always zero; the front cover body is connected with the drill bit base body of the hot melting module for transmitting the vibration generated by the piezoelectric ceramic stack to the drill bit base body. The hot melting module comprises a drill bit base body, a heating rod, a temperature sensor, a connecting stem and a pressure cabin, the heating rod is arranged inside the drill bit base body, the distance between the front end of the heating rod and the front end surface of the drill bit base body is 1 mm to 6 mm; the temperature sensor is used for monitoring the temperature of the drill bit base body; the connecting stem passes through the pressure cabin and connects the front cover body of the piezoelectric driving module with the drill bit base body of the hot melting module.
[0009] Preferably, the distance between the front end of the heating rod and the front end surface of the drill bit base body is 2 mm to 4 mm.
[0010] Further, the pre-tightening structure comprises a rear cover plate with studs and a special-shaped nut, the studs of the rear cover plate pass through the piezoelectric ceramic stack and are threadedly connected with the special-shaped nut, the axial pre-tightening force is provided by screwing the special-shaped nut; the thread on the stud of the rear cover plate is a fine thread with a pitch less than or equal to 2 mm.
[0011] Further, the heating rod is fixed in the drill bit base body by a threaded connection.
[0012] Further, the hot melting module further comprises a first heating rod guide partition plate and a second heating rod guide partition plate, both of which are fixed by the connecting stem and are used for guiding and heat insulating the wires of the heating rod.
[0013] Further, the front cover body is made of aluminum alloy, titanium alloy or magnesium-aluminum alloy.
[0014] According to the second aspect of the present application, an ice melting method based on the ultrasonic enhanced hot melting drilling tool is provided, comprising the following steps: Starting the hot melting module, heating the front end of the drill bit base body by the heating rod to melt the ice layer to form a water film; Starting the piezoelectric driving module to make the piezoelectric ceramic sheets generate axial ultrasonic vibration and transmit the ultrasonic vibration to the front end of the drill bit base body; The water film thickness at the front end of the drill bit base is controlled to be greater than the amplitude of the front end of the ultrasonic enhanced thermal melting drilling tool and less than or equal to 1 mm by controlling at least one of the heating power and the drilling pressure; The cavitation effect, the destruction of ice crystal structure and the disturbance of water body generated by the ultrasonic vibration in the water film, together with the heating effect, accelerate the melting of the ice layer and promote the ultrasonic enhanced thermal melting drilling tool.
[0015] The method for controlling the water film thickness comprises dynamically adjusting the heating power of the heating rod according to the drill bit base temperature fed back by the temperature sensor, and adjusting the drilling pressure.
[0016] To prevent the piezoelectric driving module from resonant frequency drift, sharp vibration efficiency decrease or piezoelectric ceramic sheet failure due to continuous work, the piezoelectric driving module works in an intermittent pulse mode, and the duty cycle of the piezoelectric driving module is less than or equal to 75%.
[0017] When the drill is stuck, the driving frequency of the piezoelectric driving module is adjusted to generate a composite vibration containing an axial component and a torsional component to realize vibration unjamming.
[0018] Through the above design scheme, the application has the following advantages: 1. Significantly improve the ice layer melting efficiency: the application couples the ultrasonic vibration generated by the piezoelectric driving module with the heating ice melting function of the thermal melting drilling tool. The high-frequency vibration formed at the front end of the drill bit base can destroy the ice layer crystal structure and weaken the thermal conductivity gradient of the ice, so that the heat diffusion in the ice layer is more uniform, thereby significantly improving the ice melting efficiency; under the same heating power, a faster drilling speed is realized.
[0019] 2. Utilize cavitation effect to accelerate the ice melting process: ultrasonic vibration can generate micro cavitation bubbles near the water-ice interface, and the bubbles release local high temperature and high pressure when they collapse, which helps to further break the ice crystals, loosen the interface structure, accelerate the phase change of the ice layer and improve the overall drilling speed; compared with the traditional pure thermal melting drilling tool, the application has higher energy utilization rate.
[0020] 3. Inhibit the ice layer re-freezing problem: ultrasonic vibration continuously disturbs the melted water body, inhibits the formation of stable temperature gradient in the local stationary water body, and reduces the possibility of re-freezing of the water body on the outer wall of the drilling tool, thereby significantly reducing common faults such as blockage and seizure, and improving the continuous drilling capability.
[0021] 4. Provide active unblocking function to improve operation safety: when the drill tool is stuck, the invention can make the piezoelectric drive module work in low-frequency torsional vibration mode by adjusting the drive frequency, generate axial and micro-torsional composite vibration, so as to make the drill bit base and the surrounding ice wall produce micro-loose displacement, which has the effect of "vibration unblocking". This function can effectively reduce the risk of drill tool sticking and improve the operation safety in polar drilling and planetary exploration.
[0022] 5. Compact structure and high integration: the piezoelectric ceramic sheet, positive and negative electrode conductive sheet and pressure tank of the invention are arranged along the axial direction of the drill tool, so that the overall structure is compact, easy to miniaturize and suitable for narrow drilling environment, deep ice layer drilling or probe carrying task.
[0023] 6. Strong environmental adaptability: the piezoelectric ceramic sheet has a wide temperature resistance range and is not affected by electromagnetic interference, so the invention can be well applied to low-temperature environment and can withstand high temperature generated by the hot melting drill tool to work stably.
[0024] 7. Significantly reduce the weight of the hot melting drill tool: the traditional hot melting drill tool needs counterweight to increase the drilling pressure, and the drilling pressure required by the hot melting drill tool is significantly reduced after ultrasonic vibration, so as to reduce the weight of the drill tool. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 A schematic diagram of the overall system of the ultrasonic enhanced hot melting drill tool for ice layer drilling is provided for the embodiment of the invention. Figure 2 For Figure 1 local enlargement Figure 1 ; Figure 3 For Figure 1 local enlargement Figure 2 ; Figure 4 The working amplitude schematic diagram of the ultrasonic enhanced hot melting drill tool using half-wave ultrasonic system structure in the embodiment of the invention.
[0026] In the figure: 1 - waterproof joint; 2 - piezoelectric tank rear cover; 3 - first O-shaped sealing ring; 4 - piezoelectric tank shell; 5 - rear cover plate; 6 - piezoelectric ceramic sheet; 7 - negative electrode conductive sheet; 8 - positive electrode conductive sheet; 9 - first screw; 10 - second O-shaped sealing ring; 11 - special-shaped nut; 12 - front cover body; 13 - temperature sensor; 14 - cable plug; 15 - connecting core rod; 16 - pressure tank; 17 - second screw; 18 - first heating rod wire partition plate; 19 - fuse holder; 20 - second heating rod wire partition plate; 21 - heating rod; 22 - drill bit base. DETAILED DESCRIPTION
[0027] In order to make the objects, features and advantages of the present application more apparent, the present application will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. Those skilled in the art will understand that the specific description below is illustrative rather than limiting and is not intended to limit the scope of the present application. Unless otherwise defined, technical terms or scientific terms used herein should be understood as commonly understood by those skilled in the art to which the present application belongs. In order to avoid obscuring the essence of the present application, well-known methods, processes, procedures, elements and circuits are not described in detail.
[0028] As shown in Figure 1 , Figure 2 and Figure 3 , an ultrasonic enhanced thermal melting drill for ice layer drilling includes a piezoelectric drive module and a thermal melting module.
[0029] The piezoelectric drive module includes a waterproof joint 1, a piezoelectric cabin rear cover 2, a first O-ring 3, a piezoelectric cabin shell 4, a rear cover plate 5, a piezoelectric ceramic stack, a first screw 9, a second O-ring 10, a special-shaped nut 11 and a front cover body 12.
[0030] The cable of the waterproof joint 1 is fixed in the hole of the piezoelectric cabin rear cover 2 by sealing glue, and the piezoelectric cabin rear cover 2 is connected on the piezoelectric cabin shell 4 through its own thread. The piezoelectric cabin shell 4 is fixed on the front cover body 12 by the first screw 9. The rear cover plate 5 is provided with a stud, the stud of the rear cover plate 5 passes through the piezoelectric ceramic stack, then passes through the hole on the front cover body 12, and the piezoelectric ceramic stack is fastened by the special-shaped nut 11 with pre-tightening force. The piezoelectric ceramic stack is arranged in the piezoelectric cabin shell 4, and the piezoelectric ceramic stack is composed of a plurality of piezoelectric ceramic sheets 6 and positive and negative conductive sheets 7 alternately arranged between adjacent piezoelectric ceramic sheets 6, preferably, the number of piezoelectric ceramic sheets 6 is ten. The rear cover plate 5 is arranged behind the piezoelectric ceramic stack and is not connected with the piezoelectric cabin shell 4, and serves as a mechanical boundary condition of the entire piezoelectric drive module. Its main functions include forming an acoustic reflection and isolation structure to suppress energy leakage backward, and providing the required axial pre-tightening force for the piezoelectric ceramic stack to ensure that the piezoelectric ceramic sheet 6 only bears uniform axial pre-stress. It should be noted that the pre-tightening force in the application is the concentrated force borne by the piezoelectric ceramic stack, and the pre-stress is the distributed force borne by the single piezoelectric ceramic sheet 6. The first O-shaped sealing ring 3 and the second O-shaped sealing ring 10 are used for sealing the piezoelectric drive module, wherein the first O-shaped sealing ring 3 is arranged in the sealing ring groove at the rear end of the piezoelectric cabin shell 4, the piezoelectric cabin shell 4 and the piezoelectric cabin rear cover 2 cooperate to compress the first O-shaped sealing ring 3, thereby realizing the sealing effect; the second O-shaped sealing ring 10 is arranged in the sealing ring groove at the front end of the piezoelectric cabin shell 4, the piezoelectric cabin shell 4 and the front cover body 12 cooperate to compress the second O-shaped sealing ring 10, thereby realizing the sealing effect. The piezoelectric cabin shell 4 is fixed on the displacement node surface (i.e. the plane on the front cover body 12 where the vibration displacement is always zero) of the front cover body 12, otherwise the piezoelectric cabin shell 4 will vibrate with the front cover body 12, thereby consuming part of the vibration energy and affecting the drilling efficiency.
[0031] In order to ensure that the pre-stress between the contact surfaces of the rear cover plate 5, the front cover body 12 and the piezoelectric ceramic sheet 6 of the piezoelectric drive module is uniform, and to ensure that the piezoelectric drive module has a high mechanical quality factor and a low mechanical loss, the thread on the stud of the rear cover plate 5 should be a fine thread, and the pitch should be less than or equal to 2 mm. Since the tensile strength of the piezoelectric ceramic sheet 6 is low and the compressive strength is high, the pre-stress needs to be kept within a reasonable range, and its applied value should be adjusted to be greater than the maximum tensile stress encountered by the piezoelectric drive module during operation.
[0032] The hot melting module comprises a temperature sensor 13, a cable plug 14, a connecting core rod 15, a pressure cabin 16, a second screw 17, a first heating rod guide baffle 18, a fuse holder 19, a second heating rod guide baffle 20, a heating rod 21 and a drill bit base 22. The temperature sensor 13 and the cable plug 14 are fixed on the pressure cabin 16. The temperature sensor 13 is used for measuring the real-time temperature of the drill bit base 22, so as to coordinate the heating efficiency and the ultrasonic driving parameters, thereby adjusting the drilling efficiency. The cable plug 14 is used for connecting the wires led out from the fuse holder 19. The wires at the other end of the fuse holder 19 are connected with the heating rod 21. The cable led out from the cable plug 14 is connected with the waterproof joint 1 through the back cover plate 5. The connecting core rod 15 passes through the pressure cabin 16. One end of the connecting core rod 15 is screwed on the drill bit base 22, and the other end of the connecting core rod 15 is used for pressing and fixing the pressure cabin 16 on the drill bit base 22 through a nut. The pressure cabin 16 plays a sealing protection role and can effectively isolate the melted water from invading the inside, so as to prevent the key components such as the heating rod 21 and the fuse holder 19 from being damaged due to contact with the liquid. The fuse holder 19 is fixed on the second heating rod guide baffle 20 by means of a screw. The first heating rod guide baffle 18 and the second heating rod guide baffle 20 are respectively fixed on the connecting core rod 15 by means of the second screw 17. The heating rod 21 is inserted into the inner hole of the drill bit base 22.
[0033] The vibration is transmitted through the front cover body 12, the pressure cabin 16 and the drill bit base 22 in stages. The front cover body 12, the pressure cabin 16 and the drill bit base 22 are all regarded as the front cover plate of the conventional sandwich piezoelectric transducer. The position of the heating rod 21 must be in front, so as to ensure that the thickness of the melted water film is limited within a certain range, thereby ensuring the occurrence of ultrasonic cavitation.
[0034] The pre-tightening force of the piezoelectric ceramic stack is accurately controlled through the special-shaped nut 11, so that the working frequency of the piezoelectric driving module is stable, and the frequency deviation caused by low temperature is avoided. The piezoelectric driving module is arranged in an axial direction, so that the vibration direction is completely consistent with the heat flow direction, thereby forming a longitudinal vibration coupling effect.
[0035] The cable plug 14 and the fuse holder 19 jointly constitute an internal power supply and protection system, which can cut off the heating or ultrasonic power supply in abnormal conditions, thereby ensuring the safety of the device.
[0036] Since the ultrasonic cavitation inputs concentrated energy (acoustic energy) into the local water to excite cavitation, the ultrasonic wave intensity increases, and the cavitation intensity increases. However, when the ultrasonic wave intensity reaches a certain value, the cavitation tends to be saturated. At this time, increasing the ultrasonic wave intensity will produce a large number of useless cavities, thereby increasing the scattering attenuation, and thus reducing the cavitation intensity. The lower the ultrasonic frequency, the easier it is to produce cavitation in the liquid. Therefore, the ultrasonic frequency of the ultrasonic enhanced hot melting drilling tool is set to 20 kHz-40 kHz. That is, when the ultrasonic enhanced hot melting drilling tool is designed, the sizes of various components should be reasonably designed, so that the longitudinal vibration frequency is 20 kHz-40 kHz.
[0037] The position of the heating rod 21 needs to be designed reasonably. If the distance is too large, it will lead to increased heat loss and be detrimental to heat conduction. If the distance is too small, the heating rod 21 will be directly exposed to the impact environment of the ice layer and will also affect the ultrasonic coupling. Therefore, in order to ensure stable and efficient heat conduction, the distance from the front end of the heating rod 21 to the front end of the drill bit base 22 is set to 1mm to 6mm, preferably 2mm to 4mm. At the same time, due to the generation of mechanical vibration, the heating rod 21 may be damaged if it is fixed too loosely. Therefore, the heating rod 22 is screwed in by a top thread connection.
[0038] During drilling, the melting rate at the front end of the drill bit base 22 is controlled by coordinating the coupling ratio of heating power and ultrasonic power, the lowering speed, and the drilling pressure. Furthermore, before drilling begins, the weight of the entire drill string must be adjusted to maintain the drilling pressure. Excessive drilling pressure can cause the resonant frequency of the piezoelectric drive module to drift, the amplitude to decrease, or losses to increase, while insufficient drilling pressure can prevent adequate drilling efficiency. This ensures stable and efficient operation of the ultrasonic-enhanced thermal fusion drill string. The drilling speed is controlled by adjusting the coupling ratio of heating power and ultrasonic power, the drilling speed, the drilling pressure, and the structure of the front end of the drill bit base 22.
[0039] In addition, since the piezoelectric drive module generates heat during long-term operation, the duty cycle (the percentage of ultrasonic application time in the total working time) needs to be selected reasonably during drilling. For example, if a 50% duty cycle is selected, the piezoelectric drive module will work for 15 seconds during a 30-second drilling time, and the rest of the time will be used for heat dissipation.
[0040] To ensure that ultrasonic energy is radiated as high as possible from the front end of the piezoelectric drive module, the front cover 12 is made of lightweight metals such as aluminum alloy, titanium alloy, and magnesium-aluminum alloy. To reduce the energy radiated from the rear end of the piezoelectric drive module, the rear cover 5 is made of heavy metals such as 45 steel and brass.
[0041] The ultrasonic-enhanced thermal fusion drill bit proposed in this invention adopts a half-wavelength ultrasonic system structure, and the working amplitude diagram is shown below. Figure 4 As shown, Figure 4 In the diagram, 'a' represents the amplitude of the rear cover plate, and 'b' represents the working amplitude. Ultrasonic vibration forms an effective acoustic pressure field at the front end of the drill bit base 22. The coupling effect with the thermal field ensures that the melt water film maintains a stable thickness, thereby achieving directional vibration enhancement of the ice-water interface. To achieve efficient and stable thermo-acoustic coupled drilling, the geometric dimensions of the core components of the ultrasonic-enhanced thermo-melting drill bit (including the rear cover plate 5, the front cover 12, and the drill bit base 22) need to be collaboratively designed through system modal analysis and harmonic response analysis to ensure that the ultrasonic-enhanced thermo-melting drill bit is in a resonant state at the target working frequency (20kHz~40kHz) and outputs a longitudinal vibration displacement amplitude that meets the requirements at the front end of the drill bit base 22.
[0042] The specific design principles and key dimensional parameter ranges are as follows: The rear cover plate 5 is designed as a variable cross-section column. Its axial length needs to be matched with the thickness of the selected piezoelectric ceramic stack and the length of the front cover 12 through the half-wavelength theory. The axial length range is usually 1 / 4 wavelength.
[0043] The front cover 12, as a key component for vibration transmission and amplification, is typically designed as an amplitude transformer (e.g., stepped). Its input end diameter (connected to the piezoelectric ceramic stack), output end diameter (connected to the drill bit base 22), and length together determine the displacement amplification factor of the ultrasonically enhanced thermoelectric drill bit. The total length of the front cover 12 is typically 1 / 4 wavelength. The input end diameter of the front cover 12 needs to match the outer diameter of the piezoelectric ceramic stack, while the output end diameter is determined based on the dimensions of the drill bit base 22 and the required output amplitude. Its precise profile dimensions need to be optimized through finite element modal analysis to achieve the desired resonant frequency and amplification effect.
[0044] As the working component that directly interacts with the ice layer, the geometry of the drill bit body 22 directly affects the heat transfer efficiency and sound field distribution. The drill bit body 22 is rigidly connected to the output end of the front cover 12, and its axial length must also be considered in the entire half-wavelength resonant system. The coordinated design of the rear cover 5, the front cover 12, and the drill bit body 22 aims to ensure that the entire ultrasonic-enhanced thermal fusion drill bit achieves longitudinal resonance at the target operating frequency of the piezoelectric drive module, maximizing energy transfer efficiency; and ensuring that the required ultrasonic vibration amplitude (i.e.,...) is generated at the working face of the drill bit body 22's front end. Figure 4 The operating amplitude b is crucial for forming an effective sound pressure field and achieving stable coupling with the thermal field.
[0045] When the ultrasonic-enhanced thermomelting drill bit is designed and operates according to the above principles, the high-frequency vibration at the front end of the drill bit base 22 generates a strong acoustic pressure field (including acoustic flow and cavitation effects) in the melt water film in front of it. This acoustic pressure field couples with the thermal field provided by the drill bit base 22, enhancing heat transfer through convection and disturbing the melt water film, ensuring that the melt water film maintains a stable optimal thickness. In this invention, the melt water film thickness is controlled to be greater than the amplitude of the front end of the ultrasonic-enhanced thermomelting drill bit and less than or equal to 1 mm. This stable water film is the foundation for achieving efficient and stable thermomelting drilling because it ensures that heat is continuously and efficiently transferred to the ice-water interface, while facilitating the discharge of melt water. By limiting and optimizing the above-mentioned structural dimensions, operating parameters, and their coupling relationships, this invention ensures the reliable implementation of ultrasonic-enhanced thermomelting drilling.
[0046] This invention proposes a novel drill bit structure that combines thermal fusion drilling with ultrasonic vibration. High-frequency vibration improves heat transfer, disrupts ice crystal structures, and accelerates melting through cavitation, resulting in higher drilling speeds, lower energy consumption, and a more stable melting interface. Furthermore, the application of ultrasonic vibration significantly reduces the drilling pressure required for the thermal fusion drill bit, thereby making it lighter.
[0047] Working principle of the invention: When the ultrasonic-enhanced thermal fusion drilling tool of the present invention is in operation, it is connected to an external power supply and control signal through a waterproof connector 1, which are respectively transmitted to the piezoelectric drive module and the thermal fusion module, thereby realizing coordinated drilling control.
[0048] When the equipment is started, the temperature sensor 13 first monitors the temperature of the drill bit base 22 in real time and feeds the detection signal back to the external control system to adjust the output power of the heating rod 21. The heating rod 21 is located inside the drill bit base 22 and provides heat directly to the front ice layer, causing the ice layer to heat up rapidly and form an initial meltwater layer. The first heating rod wire separator 18 and the second heating rod wire separator 20 provide thermal insulation support for the wiring of the heating rod 21, preventing ineffective heat conduction to the rear end and improving heating efficiency.
[0049] Meanwhile, under the action of a high-frequency sinusoidal alternating current applied to the positive electrode conductive plate 8 and the negative electrode conductive plate 7, the piezoelectric ceramic plate 6 generates high-frequency mechanical vibrations of 20kHz to 40kHz. The high-frequency vibrations generated by the piezoelectric ceramic plate 6 are transmitted to the drill bit base 22 through the front cover 12 and the pressure chamber 16, forming stable longitudinal ultrasonic vibrations.
[0050] The combined effects of ultrasonic vibration and front-end thermal melting on the ice layer are as follows: 1. Interface fragmentation effect: High-frequency vibration causes microcracks in the ice crystal structure, reducing the strength of the ice and improving the thermal melting efficiency; 2. Acoustic flow and disturbance effect: Micro-circulation flow is formed in the meltwater layer, which accelerates interfacial heat exchange and makes the temperature gradient tend to be uniform; 3. Microcavitation effect: During the drilling process into ice, the thermal fusion drill bit forms a water film at the level of tens to hundreds of μm, unlike a conventional liquid tank. After applying ultrasound, the ultrasonic-enhanced thermal fusion drill bit can generate transient microbubbles in the melt water. The collapse of these cavitation bubbles generates microjets with speeds up to hundreds of meters per second. These microjets cause asymmetric collapse and microflow of the bubbles, absorbing more energy, leading to an increase in temperature, reducing the heat and mass transfer resistance at the ice / water interface, accelerating the phase change rate from ice to water, and forming a strong mechanical impact near the contact area between the water film and the ice layer, further accelerating the breaking and melting of the ice layer. 4. Reduce stuck drill accidents: Vibration can reduce the adhesion of ice to the drill bit substrate 22, thereby reducing the possibility of stuck drill.
[0051] As the drill bit body 22 advances forward, the melted water naturally drains out along the outer surface of the drill bit body 22 and will not refreeze on the sidewall of the drill bit; the heating rod 21 and the piezoelectric drive module work together dynamically under the regulation of the control system to enable the drill bit body 22 to continuously and stably penetrate into the ice layer.
[0052] Through the aforementioned thermal-ultrasonic coupling working mechanism, this invention achieves low energy consumption, high stability, and high-speed drilling, making it particularly suitable for exploration and sampling missions in polar ice caps, thick glacial ice layers, frozen soil layers, and planetary ice shell environments.
Claims
1. An ultrasonically enhanced thermo-fusion drill for ice drilling, characterized in that, It includes a piezoelectric drive module and a thermal melting module; the piezoelectric drive module is used to generate and transmit axial ultrasonic vibrations; the thermal melting module is used to heat and melt ice. The vibration output end of the piezoelectric drive module is connected to the drill bit base (22) of the heat fusion module, so that the ultrasonic vibration can be transmitted to the front end of the drill bit base (22) and work together with the heat generated by the heat fusion module to accelerate the melting of ice and inhibit the refreezing of meltwater. The piezoelectric drive module has a drive frequency range of 20kHz to 40kHz. The piezoelectric drive module includes a piezoelectric chamber housing (4), a piezoelectric ceramic stack disposed in the piezoelectric chamber housing (4), a pre-tightening structure for applying axial pre-tightening force to the piezoelectric ceramic stack, and a front cover (12). The piezoelectric ceramic stack consists of multiple piezoelectric ceramic sheets (6) and positive conductive sheets (8) and negative conductive sheets (7) alternately disposed between adjacent piezoelectric ceramic sheets (6). The front cover (12) is connected to the front end of the piezoelectric ceramic stack, and the piezoelectric chamber housing (4) is fixed to the plane where the vibration displacement of the front cover (12) is always zero. The front cover (12) is connected to the drill bit base (22) of the thermal fusion module and is used to transmit the vibration generated by the piezoelectric ceramic stack to the drill bit base (22). The heat fusion module includes a drill bit body (22), a heating rod (21), a temperature sensor (13), a connecting core rod (15), and a pressure chamber (16). The heating rod (21) is disposed inside the drill bit body (22). The distance between the front end of the heating rod (21) and the front end face of the drill bit body (22) is 1 mm to 6 mm. The temperature sensor (13) is used to monitor the temperature of the drill bit body (22). The connecting core rod (15) passes through the pressure chamber (16) and connects the front cover (12) of the piezoelectric drive module to the drill bit body (22) of the heat fusion module.
2. The ultrasonic-enhanced thermo-fusion drill for ice drilling according to claim 1, characterized in that, The distance between the front end of the heating rod (21) and the front end face of the drill bit base (22) is 2mm to 4mm.
3. The ultrasonic-enhanced thermo-fusion drill for ice drilling according to claim 1, characterized in that, The pre-tightening structure includes a rear cover plate (5) with a stud and a shaped nut (11). The stud of the rear cover plate (5) passes through the positive conductive sheet (8), the negative conductive sheet (7) and the piezoelectric ceramic sheet (6) and then engages with the shaped nut (11) by threading. The axial pre-tightening force is provided by tightening the shaped nut (11). The thread on the stud of the rear cover plate (5) is a fine thread with a pitch of less than or equal to 2 mm.
4. The ultrasonic-enhanced thermo-fusion drill for ice drilling according to claim 1, characterized in that, The heating rod (21) is fixed inside the drill bit body (22) by a threaded connection.
5. The ultrasonic-enhanced thermo-fusion drill for ice drilling according to claim 1, characterized in that, The heat fusion module also includes an upper heating rod guide partition (18) and a lower heating rod guide partition (20), which are fixed by the connecting core rod (15) and are used to guide and insulate the wires of the heating rod (21).
6. The ultrasonic-enhanced thermo-fusion drill for ice drilling according to claim 1, characterized in that, The front cover (12) is made of aluminum alloy, titanium alloy or magnesium-aluminum alloy.
7. A method for melting ice based on the ultrasonically enhanced thermal fusion drill according to any one of claims 1-6, characterized in that, Includes the following steps: The heat fusion module is activated, and the front end of the drill bit base (22) is heated by the heating rod (21) to melt the ice layer and form a melt water film; The piezoelectric drive module is activated to generate axial ultrasonic vibration in the piezoelectric ceramic sheet (6) and transmit the ultrasonic vibration to the front end of the drill bit body (22); By controlling at least one parameter of heating power and drilling pressure, the thickness of the melt water film at the front end of the drill bit substrate (22) is controlled to be greater than the amplitude at the front end of the ultrasonically enhanced thermal fusion drill bit and less than or equal to 1 mm; The ultrasonic vibration generates cavitation in the meltwater film, destroys the ice crystal structure, and disturbs the water, which, in conjunction with the heating effect, accelerates the melting of the ice layer and propels the ultrasonic-enhanced thermal fusion drill bit.
8. The ice-melting method according to claim 7, characterized in that, The method for controlling the thickness of the melt film includes: dynamically adjusting the heating power of the heating rod (21) based on the temperature of the drill bit substrate (22) fed back by the temperature sensor (13), and adjusting the drilling pressure accordingly.
9. The ice-melting method according to claim 7, characterized in that, The piezoelectric drive module operates in an intermittent pulse mode, with a duty cycle of less than or equal to 75%.
10. The ice-melting method according to claim 7, characterized in that, When a stuck drill occurs, the driving frequency of the piezoelectric drive module is adjusted to generate a composite vibration containing axial and torsional components, thereby achieving vibration-based unblocking.