A small-diameter grooved heat pipe strong cavitation composite polishing device and method

Abstract

The present invention provides a small-diameter grooved heat pipe strong cavitation composite polishing device and method. The device includes a liquid suction pipe, a vacuum structure, a sealed cavity, a liquid storage tank, a driving mechanism, a nozzle, a polishing fixture, and a fixture base. The grooved heat pipe is fixed on the polishing fixture, the polishing fixture is placed on the fixture base, and the fixture base is fixed at the bottom of the sealed cavity. The liquid storage tank contains polishing liquid. One end of the liquid suction pipe extends into the liquid storage tank, and the other end is inserted into the sealed cavity and connected to the nozzle to transport the polishing liquid in the liquid storage tank to the nozzle for polishing the inside of the grooved heat pipe. The liquid suction pipe and the sealed cavity are sealed and connected through a sealing ring. The driving mechanism is connected to the nozzle to realize the rotation of the nozzle. The vacuum structure is hermetically connected to the sealed cavity to pump out the air inside the sealed cavity. The composite polishing device of the present invention has good airtightness, strong operability, and high stability.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing part polishing, and more particularly, to a strong cavitation composite polishing device and method for small-diameter grooved heat pipes. Background Art

[0002] A heat pipe is a thermal control device that uses the latent heat of gas-liquid phase change to rapidly transport heat over a long distance, and has a high heat transfer coefficient and heat transfer capacity. Grooved heat pipes are widely used in fields with thermal control requirements such as spacecraft and electronic chips due to their unique advantages in microscale heat transfer, microfluidics, and microphase change. Currently, with additive manufacturing printing technology, it is possible to achieve the integrated molding of complex spatially helically bent or crossed-structured grooved heat pipes and spacecraft structural components. However, there are a large number of floating powders and slag on the surface of additive manufacturing parts, which block the microchannels of the grooves, and the groove surface is very rough, seriously restricting the thermal conductivity of the grooved heat pipes. As the industry's requirements for the inner surface quality of grooved heat pipes become higher and higher, traditional automatic polishing processes are difficult to perform high-precision polishing on small-sized inner surfaces, and abrasive and fluid mixture jet polishing methods have been widely applied and developed.

[0003] Zhejiang University of Technology continuously flows a soft abrasive polishing liquid over the surface of the workpiece to obtain a smooth workpiece surface, verifying the feasibility of high-precision abrasive flow polishing, but this method has the problem of too long polishing time. The single abrasive flow polishing method can improve the polishing accuracy, but it is difficult to improve the polishing efficiency. China Jiliang University uses an ultrasonic and abrasive flow composite method to polish the surface of the workpiece; Chinese patents CN102672554B and CN102873643B propose using a negative pressure and abrasive flow composite method to polish circular curved surfaces. The above methods reflect the development process from planar polishing to curved surface polishing and from single polishing methods to composite polishing methods, but existing polishing methods and devices are still difficult to effectively polish the inner surface of grooved pipes. Among existing groove structures, rectangular and Ω-shaped are more common. The groove profile is approximately a C-shaped surrounding structure, and the connection space with the main channel of the heat pipe is relatively narrow. It is difficult for abrasives to enter the grooves, and the heat pipe has a small diameter and a long size, increasing the polishing difficulty. Compared with planar and curved surface polishing, when polishing the inner surface of grooved heat pipes, in addition to ensuring the polishing efficiency and quality, polishing consistency should also be emphasized.

[0004] Therefore, it is crucial to propose a polishing method and device suitable for the inner surface of small-diameter grooved heat pipes. Summary of the Invention

[0005] In view of the technical problems of low polishing efficiency, poor polishing quality and insufficient polishing consistency on the inner surface of the additive manufacturing large aspect ratio complex groove heat pipe by the existing polishing methods and devices proposed above, a strong cavitation composite polishing device and method for small-diameter groove heat pipes are provided. The present invention mainly uses a strong cavitation composite polishing method and device formed by combining abrasive water jet polishing with negative pressure cavitation and ultrasonic cavitation to solve the polishing problem of the inner surface of the groove heat pipe. A special device is designed for the composite polishing method. The driving motor is fixed on one side of the sealed cavity and fixedly connected to the polishing rotating shaft through a coupling. The rotating shaft drives the nozzle to rotate stably under the clamping of the rotating fixture. The polishing liquid enters the rotating shaft through the liquid suction pipe under the action of the liquid suction pump, then enters the five-stage variable diameter nozzle and finally rotates and sprays out. The nozzle enters the heat pipe to maintain polishing tightness. The groove heat pipe has a small diameter, a long length, and a large impact of the polishing liquid jet. The device is fixed and supported by the polishing fixture and the base, and the relative position of the nozzle and the heat pipe is also ensured. The device can realize the rotary spraying of the polishing liquid to polish the inner surface of the pipeline. The ultrasonic device acts on the entire heat pipe through the generating platform, and the ultrasonic platform is clamped and fixed to the heat pipe through the fixture; the air suction pump extracts the air in the sealed cavity through the air suction pipe, and the sealing ring ensures the tightness of the cavity. The internal pressure of the cavity is observed through the pressure valve to make it reach a vacuum degree of -2; the bottom of the sealed cavity is connected to the outside by a liquid suction pipe, and the liquid suction pipe is connected to the liquid storage tank through the liquid suction pump, thus forming a composite polishing device with a sealed cavity and an overall circulation. Under the negative pressure environment of the cavity, there is a high pressure difference at the nozzle. The polishing liquid flows from the liquid storage tank to the sealed cavity. After the polishing liquid flows out of the nozzle, it quickly cavitates under the action of the pressure difference. A large number of tiny bubbles in the polishing liquid quickly collapse, and the local micro-jet generated by the collapse of the bubbles has an obvious effect on material removal; the liquid flow rate is increased by pressurizing with the liquid suction pump, so that the liquid is ejected at a high speed at the nozzle. One is to remove materials through the impact and shearing action of high-speed abrasive grains, and the other is that the high-speed ejection makes the cavitation effect penetrate the entire pipeline. Since the jet is in a vacuum environment, the air resistance is greatly reduced, the air turbulence phenomenon at the edge of the jet is reduced, the entrainment amount and the dispersion amount of the jet are reduced, and the spraying distance is farther; the rotation of the nozzle changes the movement trajectory of the abrasive grains, so that a large number of abrasive grains directly enter the groove structure, which is more conducive to the polishing of the groove structure. The ultrasonic vibration makes a large number of micro-bubbles in the fluid continuously grow, compress and impact on the groove surface or near the surface. When the bubbles collapse, micro-jet shock waves are formed, and the impact on the nearby free abrasive grains hits the workpiece surface. The cavitation effect enhances the friction and impact of the micro-abrasive fluid on the workpiece surface, effectively improving the material removal efficiency. The strong cavitation effect of the ultrasonic plus negative pressure and abrasive flow composite polishing method and the use of the polishing device greatly improve the polishing efficiency, ensure the polishing quality of the inner surface, and have a good integrated polishing effect.

[0006] The technical means adopted by the present invention are as follows:

[0007] A small-diameter grooved heat pipe strong cavitation composite polishing device, comprising: a liquid suction pipe, a vacuum structure, a sealed cavity, a liquid storage tank placed outside the sealed cavity, and a driving mechanism, a nozzle, a polishing fixture and a fixture base placed inside the sealed cavity. The grooved heat pipe is fixed on the polishing fixture, the polishing fixture is placed on the fixture base, and the fixture base is fixed at the bottom of the sealed cavity; the liquid storage tank contains polishing liquid, one end of the liquid suction pipe extends into the liquid storage tank, and the other end is inserted into the sealed cavity and connected to the nozzle to transport the polishing liquid in the liquid storage tank to the nozzle for polishing the inside of the grooved heat pipe. The liquid suction pipe and the sealed cavity are sealed and connected through a sealing ring; the driving mechanism is connected to the nozzle for realizing the rotation of the nozzle; the vacuum structure is sealed and connected to the sealed cavity for pumping out the air inside the sealed cavity.

[0008] Further, the polishing liquid is an abrasive polishing liquid, comprising silicon dioxide abrasive grains, a stabilizer and a water-based liquid. The mass fraction of the silicon dioxide abrasive grains is 10-20%, the particle size is 0.5-10 μm, and the mass fraction of the stabilizer is 5%.

[0009] Further, the nozzle is a five-stage variable-diameter nozzle structure. The injection port of the nozzle enters the grooved heat pipe, and the injection port is in close contact with the grooved heat pipe to ensure the sealing performance of the connection.

[0010] Further, the driving mechanism includes a motor support platform, a driving motor, a coupling and a rotating shaft. The motor support platform is fixed on one side of the sealed cavity for supporting and fixing the driving motor. The driving motor is connected to the rotating shaft through the coupling for driving the rotating shaft to drive the nozzle to rotate. A rotating fixture is arranged outside the rotating shaft, and the rotating fixture is fixed on the polishing fixture to adjust the relative position between the heat pipe and the nozzle through the polishing fixture; by changing the movement track of the abrasive grains in the polishing liquid with the rotation movement of the nozzle driven by the driving motor, the movement track of the abrasive grains is a composite movement of rotation movement and linear movement, which is more conducive to the abrasive grains entering the difficult-to-polish groove structure and has a better polishing effect.

[0011] Further, it further includes an ultrasonic device. The ultrasonic device includes an ultrasonic platform and an ultrasonic generator. The grooved heat pipe is located on the ultrasonic platform. The ultrasonic platform is fixed on the polishing fixture, and the ultrasonic generator is connected to the ultrasonic platform for providing energy to the ultrasonic platform to build an ultrasonic polishing platform.

[0012] Further, the vacuum structure includes an air suction pipe and an air suction pump disposed on the air suction pipe. The air suction pump is located outside the sealed cavity. One end of the air suction pipe is inserted into the sealed cavity, and the air suction pipe is hermetically connected to the sealed cavity through a sealing ring. After the air suction pump operates, the vacuum degree inside the sealed cavity reaches -2; after the air suction pump starts, the air inside the sealed cavity is pumped out, making the internal pressure P1 of the sealed cavity much lower than the atmospheric pressure P2 outside the sealed cavity. As the nozzle serves as the connection channel between the inside and outside of the cavity, a relatively high pressure difference will be formed inside and outside the nozzle. Under the low-pressure suction effect, the polishing liquid flows to the nozzle at a certain speed through the liquid suction pipe.

[0013] Further, the liquid suction pipe is connected to one side wall or the top of the liquid storage tank; a liquid suction pump is also provided on the liquid suction pipe. The liquid suction pump is located outside the sealed cavity and is used to boost the pressure of the polishing liquid, so that the pressure difference at the nozzle reaches 0.6 - 0.8 MPa, increasing the flow rate of the polishing liquid. When the polishing liquid flows through the five-stage variable-diameter nozzle, the nozzle diameter gradually decreases, and the final jet velocity is 1 - 2 m / s.

[0014] Further, a stirrer is provided in the liquid storage tank. The stirrer stirs thoroughly in the liquid storage tank to fully mix the abrasive grains and the aqueous solution in the polishing liquid. During the polishing process, the stirrer continuously stirs to ensure the uniform dispersion of the abrasive grains.

[0015] Further, a liquid suction pipe I and a liquid suction pump I are also provided at the bottom of the sealed cavity. The liquid suction pump I is disposed on the liquid suction pipe I and is located outside the sealed cavity. One end of the liquid suction pipe I is located at the bottom end inside the sealed cavity, and the other end extends and is inserted into the liquid storage tank. Through this set of liquid suction pipe I and liquid suction pump I, the polishing liquid at the bottom of the sealed cavity is returned to the liquid storage tank to realize the recycling of the polishing liquid. The liquid suction pipe I is hermetically connected to the sealed cavity through a sealing ring.

[0016] The present invention also provides a polishing method for a small-diameter groove heat pipe strong cavitation composite polishing device, including the following steps:

[0017] Step 1: Install each device of the composite polishing device and adjust the relative positions of the nozzle and the groove heat pipe through the polishing fixture;

[0018] Step 2: Start the stirrer to stir the polishing liquid stored in the liquid storage tank. During the polishing process, the stirrer continuously stirs to keep the abrasive grains evenly dispersed in the solution;

[0019] Step 3: Start the driving motor, which drives the rotating shaft to rotate through the coupling. The rotating shaft drives the nozzle to rotate stably under the clamping of the rotating fixture;

[0020] Step 4: Start the ultrasonic device, and apply the ultrasonic vibration generated through the ultrasonic platform to the entire groove heat pipe;

[0021] Step 5: Start the suction pump. The suction pump extracts the air in the sealed cavity through the suction pipe. Observe the internal pressure of the cavity through the pressure valve and make it reach a vacuum degree of -2, so as to create a negative pressure environment in the sealed cavity. There is a large pressure difference at the nozzle, which drives the polishing liquid to flow from the liquid storage tank to the nozzle.

[0022] Step 6: Start the liquid suction pump. Increase the liquid flow rate by pressurizing with the liquid suction pump. The polishing liquid enters the rotating shaft through the liquid suction pipe under the action of the liquid suction pump, then enters the five-stage variable-diameter nozzle, and finally sprays out at high speed in a rotating manner, so that the polishing liquid rotates and sprays on the inner surface of the grooved heat pipe, realizing the composite polishing of the grooved heat pipe.

[0023] Step 7: During the polishing process, start the liquid suction pump I to return the polishing liquid during the polishing process to the liquid storage tank through the liquid suction pipe I for recycling the polishing liquid.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention use the fluid polishing liquid as the main part of the composite polishing method, which has strong adaptability to complex groove structures. Traditional methods are difficult to meet the current structural requirements. The composite polishing method has good polishing consistency and is suitable for polishing parts with complex surfaces.

[0026] 2. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention generate a large pressure difference at the nozzle in the composite polishing method, making the polishing liquid flow rapidly and strong cavitation effect occur near the wall surface. A large number of microbubbles in the fluid continuously grow - compress - collapse - impact near the wall surface. Compared with the traditional high-pressure abrasive jet, the cavitation effect in the negative pressure environment is greatly enhanced. The erosion ability of the cavitation jet is higher than that of the ordinary jet. Materials are removed during the cavitation process, and at the same time, the influence of air resistance on the jet is reduced, and the negative pressure cavitation improves the polishing efficiency.

[0027] 3. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention are based on the new cavitation jet polishing method of negative pressure cavitation effect. The polishing process is more stable. The degree of expansion of the abrasive jet beam with the increase of the polishing distance is reduced, and the jet can still maintain high-speed impact polishing at the end of the heat pipe. The traditional water jet polishing method is limited by high-pressure equipment, air turbulence and unstable material removal rate in high pressure.

[0028] 4. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention further enhance the polishing effect with an ultrasonic energy field. Under the action of ultrasonic energy, cavitation bubbles grow more rapidly, the energy released during collapse is greater, and the removal effect is better. The negative pressure environment combined with the ultrasonic energy field forms a strong cavitation and efficient removal effect, and the removal effect is higher than that of existing methods. At the same time, the stable energy field formed by the ultrasonic wave has a multiple acceleration effect on the polishing abrasive grains, improving the integrated polishing effect of the inner surface of the pipeline.

[0029] 5. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention adopt a fifth-order variable-diameter nozzle structure. Compared with traditional nozzles, the diameter is smaller, and one side of the nozzle can enter the pipeline with a higher degree of fit. At the same time, the polishing liquid can enter the groove at a higher speed and the spraying distance is farther, and the polishing distance is better than that of traditional devices.

[0030] 6. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention. In a traditional jet polishing device in a negative pressure environment, the incident angle of abrasive grains is small, which will lead to poor material removal rate and poor polishing consistency inside the groove. The composite polishing device proposes a motor-driven rotating nozzle structure, which makes the movement trajectory of the abrasive grains become a composite trajectory of linear motion and rotational motion, enabling a large number of abrasive grains to enter the groove structure. The composite polishing device also has a good polishing effect on groove structures of different shapes.

[0031] 7. The small-diameter grooved heat pipe strong cavitation composite polishing device and method provided by the present invention have good airtightness, strong operability, and high stability.

[0032] In summary, applying the technical solution of the present invention can solve the problems of low polishing efficiency, poor polishing quality, and insufficient polishing consistency of the inner surface of the additive manufacturing large aspect ratio complex grooved heat pipe by existing polishing methods and devices.

[0033] For the above reasons, the present invention can be widely promoted in the fields of polishing of additive manufacturing parts, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a schematic structural diagram of an embodiment of the small-diameter grooved heat pipe strong cavitation polishing device of the present invention.

[0036] Figure 2A C-shaped groove heat pipe structure and a sectional view related to the present invention, where (a) is a schematic diagram of the C-shaped groove heat pipe structure and (b) is a sectional view of the C-shaped groove heat pipe.

[0037] Figure 3 It is a schematic structural diagram of another embodiment of the small-diameter groove heat pipe strong cavitation polishing device of the present invention.

[0038] In the figure: 1. Liquid storage tank; 2. Stirrer; 3. Liquid suction pump; 4. Liquid suction pipe; 5. Motor support platform; 6. Driving motor; 7. Coupling; 8. Rotating shaft; 9. Rotating fixture; 10. Nozzle; 11. Groove heat pipe; 12. Air suction pipe; 13. Air suction pump; 14. Ultrasonic platform; 15. Sealed cavity; 16. Polishing fixture; 17. Ultrasonic generator; 18. Fixture base; 19. Sealing ring; 20. Liquid suction pump I; 21. Liquid suction pipe I. Detailed implementation manners

[0039] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restricts the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0041] It should be noted that the terms used here are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for the sake of convenience in description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific values should be interpreted as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0043] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by orientation terms such as "front, rear, upper, lower, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom", etc. are usually based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description. Without contrary statements, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and thus cannot be construed as limiting the protection scope of the present invention: The orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0044] For the convenience of description, spatial relative terms such as "above...", "over...", "on the upper surface of...", "above" etc. can be used here to describe the spatial positional relationships between a device or feature shown in the drawings and other devices or features. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation described in the drawings for the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "over other devices or structures" will then be positioned as "below other devices or structures" or "under other devices or structures". Thus, the exemplary term "above..." can include both the orientations of "above..." and "below...". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations should be made for the spatial relative descriptions used here.

[0045] In addition, it should be noted that the use of words such as "first", "second", etc. to limit components is only for the convenience of differentiating the corresponding components. Without additional statements, the above words have no special meanings, and thus cannot be construed as limiting the protection scope of the present invention.

[0046] The present invention mainly uses a strong cavitation composite polishing method and device formed by combining abrasive water jet polishing with negative pressure cavitation and ultrasonic cavitation to solve the polishing problem of the inner surface of a grooved heat pipe. A special device is designed for the composite polishing method. The driving motor is fixed on one side of the sealed cavity and fixedly connected to the polishing rotating shaft through a coupling. The rotating shaft drives the nozzle to rotate stably under the clamping of the rotating fixture. The polishing liquid enters the rotating shaft through the liquid suction pipe under the action of the liquid suction pump, then enters the five-stage variable-diameter nozzle and finally rotates and sprays out. The nozzle enters the heat pipe to maintain polishing tightness. The grooved heat pipe has a small diameter, a long length, and a large impact of the polishing liquid jet. The device is fixed and supported by the polishing fixture and the base, and the relative position of the nozzle and the heat pipe is also ensured. This device can realize the rotary spraying of the polishing liquid to polish the inner surface of the pipe. The ultrasonic device acts on the entire heat pipe through the generating platform, and the ultrasonic platform is clamped and fixed to the heat pipe through the fixture. The air suction pump extracts the air in the sealed cavity through the air suction pipe, and the sealing ring ensures the tightness of the cavity. The internal pressure of the cavity is observed through the pressure valve to make it reach a vacuum degree of -2. The bottom of the sealed cavity is connected to the liquid suction pipe outward, and the liquid suction pipe is connected to the liquid storage tank through the liquid suction pump, thereby forming a composite polishing device with a sealed cavity and an overall circulation. Under the negative pressure environment of the cavity, there is a large pressure difference at the nozzle. The polishing liquid flows from the liquid storage tank to the sealed cavity. After the polishing liquid flows out of the nozzle, it quickly cavitates under the action of the pressure difference. A large number of tiny bubbles in the polishing liquid quickly collapse, and the local micro-jet generated by the bubble collapse has an obvious effect on material removal. By pressurizing with the liquid suction pump to increase the liquid flow rate, the liquid is sprayed out at a high speed at the nozzle. First, material removal is achieved through the impact and shearing action of high-speed abrasive grains. Second, the high-speed spraying makes the cavitation effect penetrate the entire pipeline. Since the jet is in a vacuum environment, the air resistance is greatly reduced, the air turbulence phenomenon at the jet edge is reduced, the entrainment amount and dispersion amount of the jet are reduced, and the spraying distance is farther. The rotation of the nozzle changes the movement trajectory of the abrasive grains, enabling a large number of abrasive grains to directly enter the groove structure, which is more conducive to the polishing of the groove structure. The ultrasonic vibration causes a large number of micro-bubbles in the fluid to continuously grow, compress and impact on the groove surface or near the surface. When the bubbles collapse, micro-jet shock waves are formed, which impact the nearby free abrasive grains against the workpiece surface. The cavitation effect enhances the friction and impact of the micro-abrasive fluid on the workpiece surface, effectively improving the material removal efficiency. The strong cavitation effect of the ultrasonic plus negative pressure and abrasive flow composite polishing method and the use of the polishing device greatly improve the polishing efficiency, ensure the polishing quality of the inner surface, and have a good integrated polishing effect.

[0047] The present invention provides the following technical means:

[0048] Preferably, start the air suction pump to extract the air in the sealed cavity until the cavity reaches a vacuum degree of -2. By reading the barometer at the air suction pump, the air pump is adjusted to control the stability of the internal pressure of the cavity.

[0049] Preferably, a liquid storage tank is used to store the polishing liquid, and a stirring device continuously stirs during the polishing process to keep the abrasive grains evenly dispersed in the solution.

[0050] Preferably, the mass fraction of the abrasive grains in the polishing liquid in the liquid storage tank is 10-20%, and the abrasive grains are silicon dioxide with a particle size of 0.5-10 μm. The fine abrasive fluid shears the microscopic surface, thereby achieving micro-removal of the material.

[0051] Preferably, to better adapt to the polishing of long-distance and small-diameter groove pipeline structures, the nozzle structure is optimized. The device adopts a five-stage variable-diameter nozzle structure. The outlet size of this nozzle is smaller than the existing size, and a part of the nozzle can enter the pipeline, with good sealing performance. At the same time, at the same pressure, the spraying distance of this structure is farther, which is suitable for the polishing of slender and small-diameter groove heat pipes.

[0052] Preferably, the fluid jet with a small nozzle can generate sufficient shear stress and remove materials under high-speed impact conditions. The traditional high-pressure jet is carried out in the atmospheric air environment. The air turbulence of the high-speed fluid jet is obvious and strong, and the entrainment expansion disturbance is also strong, which is easy to produce larger polishing spots.

[0053] Preferably, the nozzle rotates and sprays at a high speed under the action of a driving motor and a rotating shaft. In the traditional device, the incident angle of the nozzle is smaller and it is not easy to enter the groove structure. However, the floating powder and slag are mainly concentrated in the groove, which will cause the problem that the polishing effect of the main channel of the heat pipe is much greater than that of the groove and a large amount of main impurities remain. In the rotating polishing nozzle device of the present invention, the movement trajectory of the abrasive grains is a composite movement of a straight line and rotation, and more abrasive grains in the polishing liquid enter the groove with more impurities. Therefore, the polishing removal rate is higher.

[0054] Preferably, compared with the traditional high-pressure abrasive jet, the cavitation effect in the negative pressure environment of the method of the present invention is enhanced, the air entrainment is smaller, and the erosion ability of the cavitation jet is higher than that of the ordinary jet. Among them, the collapse of the cavitation bubble is a main factor.

[0055] Preferably, the ultrasonic field greatly promotes the periodic cavitation effect of the cavitation bubble to expand-compress-collapse-impact near the wall surface, causing local micro-plastic deformation and micro-damage removal on the workpiece surface. The cavitation effect strengthens the disorder of the flow field, and the movement direction of the abrasive grains is more random, which can improve the processing efficiency in the low-efficiency processing area and at the same time inhibit the over-processing phenomenon in the high-efficiency processing area, thereby making the precision abrasive flow machining more reasonable and perfect.

[0056] Preferably, under the combined negative action of negative pressure cavitation and ultrasonic cavitation, a strong cavitation effect is formed on the inner surface of the pipeline, which greatly promotes the polishing efficiency of the inner surface of the pipeline.

[0057] Preferably, the groove structure in a C-shaped semi-surrounding shape has a narrow connection space with the main channel of the heat pipe. Under the impact of high-speed abrasive flow, while in a vacuum environment and an ultrasonic energy field, a single groove structure can be regarded as a simple stable flow field. In this flow field, the abrasive grains will continuously repeat the cycle of acceleration - impact - re-acceleration - re-impact, which can improve the stable polishing distance of the abrasive grains to a certain extent.

[0058] Preferably, after the groove forms a stable flow field, the pressure in the center of the flow field is higher than that of the periphery. Under the action of the pressure difference and ultrasonic waves, a large number of tiny bubbles contained in the solution will generate cavitation on the surface and near the surface of the workpiece. The bubbles grow continuously, then dent towards the surface of the workpiece, and finally collapse. At the moment of bubble collapse, a strong shock wave is generated in a small range, directly impacting the surface of the workpiece or impacting the surrounding free abrasive grains and then impacting the surface of the workpiece, thereby realizing the removal of impurities on the surface of the workpiece.

[0059] Preferably, the device of the present invention has good sealing performance, realizes the recycling of the polishing liquid, and can carry out the polishing work continuously for a long time.

[0060] Example 1

[0061] As Figure 1 shown, a small-diameter groove heat pipe strong cavitation composite polishing device includes a liquid suction pipe 4, a liquid suction pipe I 21, an air suction pipe 12, an ultrasonic platform 14, an ultrasonic generator 17, a sealed cavity 15, a liquid storage tank 1, a stirrer 2, a liquid suction pump 3, and a liquid suction pump I 20 placed outside the sealed cavity 15, and a motor support platform 5, a driving motor 6, a coupling 7, a rotating shaft 8, a rotating fixture 9, a nozzle 10, an air suction pump 13, a polishing fixture 16, and a fixture base 18 placed inside the sealed cavity 15.

[0062] The liquid storage tank 1 is connected to the mixer 2 and the liquid suction pipe 4. The liquid suction pipe 4 is connected to the liquid suction pump 3. The liquid suction pipe 4 is hermetically connected to the left side wall of the sealed cavity 15 through the sealing ring 19. The liquid suction pipe 4 passes through the sealing ring 19 and the rotating fixture 9 and then reaches the rotating shaft 8. The rotating shaft 8 is connected to the driving motor 6 through the coupling 7. The driving motor 6 is fixed to the motor support platform 5 by bolts. The other end of the rotating shaft 8 is connected to the nozzle 10 to drive the nozzle 10 to rotate. A part of the nozzle 10 enters the grooved heat pipe 11. Under the action of the polishing fixture 16, the positions of the nozzle 10 and the grooved heat pipe 11 are always fixed. The fixture base 18 is fixedly connected to the polishing fixture 16 to ensure the stable polishing of the entire device. The ultrasonic platform 14 is located between the grooved heat pipe 11 and the polishing fixture 16. The ultrasonic generator 17 provides energy for the ultrasonic platform 14 to build a stable ultrasonic polishing platform. The suction pump 13 is connected to the sealed cavity 15 through the suction pipe 12 and the sealing ring 19. After the suction pump 13 works, the internal vacuum degree of the sealed cavity 15 reaches -2. The inside of the sealed cavity 15 is a vacuum environment, and the outside is an atmospheric environment. The pressure difference between the inside and outside of the cavity is large. The polishing liquid at the bottom of the sealed cavity 15 is recycled back to the liquid storage tank 1 through another set of liquid suction pipe Ⅰ21 and liquid suction pump Ⅰ20 for recycling the polishing liquid.

[0063] The abrasive polishing liquid used in this embodiment is composed of silicon dioxide abrasive with a mass fraction of 10-20% and a particle size of 0.5-10 μm, a stabilizer with a mass fraction of 5%, and a water-based liquid.

[0064] In this embodiment, the mixer is fully stirred in the liquid storage tank to fully mix the abrasive and the aqueous solution. During the polishing process, the mixer continues to stir to ensure the uniform dispersion of the abrasive.

[0065] In this embodiment, the fixture base is fixed in the sealed cavity to support the polishing fixture and the rotating fixture. The polishing fixture is used to fix the grooved heat pipe and the nozzle fixture. The polishing fixture can adjust the relative position of the heat pipe and the nozzle, and the support device has good stability.

[0066] In this embodiment, the motor support platform is fixed to one side of the sealed cavity to support the driving motor. The driving motor drives the rotating shaft to rotate through the coupling. The rotating shaft is fixedly connected to the nozzle. The nozzle injection port enters the grooved heat pipe. Since the diameter of the grooved heat pipe is small, the nozzle and the heat pipe can be in close contact to ensure the sealing performance of the connection. At the same time, the rotation of the nozzle with the motor changes the movement trajectory of the abrasive. The movement trajectory is a composite movement of rotational movement and linear movement, which is more conducive to the abrasive entering the difficult-to-polish groove structure and has a better polishing effect.

[0067] In this embodiment, the suction pump is connected to the sealed cavity through a suction pipe, and the suction pipe and the sealed cavity are hermetically connected through a sealing ring. After the suction pump is started, the air inside the sealed cavity is pumped out, resulting in the internal pressure P1 of the cavity being much lower than the atmospheric pressure P2 outside the cavity. As the nozzle serves as the connection channel between the inside and outside of the cavity, a relatively high pressure difference will be formed inside and outside the nozzle. Under the effect of the low-pressure suction, the polishing liquid flows to the nozzle through the liquid suction pipe at a certain speed. The suction pipe is connected to one side wall or the top of the sealed cavity.

[0068] In this embodiment, the liquid suction pump is further used to increase the pressure of the polishing liquid, so that the pressure difference at the nozzle reaches 0.6 - 0.8 MPa, increasing the flow rate of the polishing liquid. When the polishing liquid flows through the five-stage variable-diameter nozzle, the nozzle diameter gradually decreases, and the final jet velocity is 1 - 2 m / s. In addition, the air resistance in the polishing environment is greatly reduced, so the polishing distance is farther and the polishing effect inside the pipeline is more stable.

[0069] In this embodiment, after the abrasive flow is sprayed from the nozzle onto the workpiece surface at a high speed, the abrasives impact the materials at the protrusions and peaks of the workpiece surface at a certain angle and speed, so as to achieve the purpose of material removal.

[0070] In this embodiment, under the condition of high pressure difference, the cavitation in the polishing liquid is more intense. The local instantaneous impact energy under cavitation is huge, and the randomness of the impact also reduces the material removal in a single direction, making the polishing efficiency higher and the polishing quality better.

[0071] In this embodiment, the grooved heat pipe is located on the ultrasonic generating platform and is also affected by ultrasonic vibration during the negative pressure polishing process. Under the action of ultrasonic energy, cavitation bubbles are generated, grow and collapse rapidly and periodically on the workpiece surface. The local high-pressure jet generated by the collapse of the cavitation bubbles pushes the liquid and abrasives to impact the workpiece surface, generating a micro-removal effect.

[0072] In this embodiment, under the combined action of ultrasonic cavitation and negative pressure cavitation in this device and method, without interference, under the formed strong cavitation effect, the polishing effect on the inner surface of the grooved heat pipe is better and the polishing efficiency is higher. Under the action of ultrasonic, negative pressure and the device, the integrated polishing effect on the inner surface of the pipeline is also significantly improved.

[0073] In this embodiment, the structure of the polishing heat pipe is usually Figure 1 the straight cylinder structure in, and the present invention also provides a C-shaped grooved heat pipe structure and cross-section as shown in Figure 2 . The polishing fixture has the function of adjustable height and still has a good fixing and supporting effect on special structure heat pipes such as C-shaped except for the straight cylinder structure. This device and method are still applicable to other pipeline structures.

[0074] In this embodiment, the liquid suction pump and the liquid suction pipe located at the bottom of the sealed cavity can suck out the polishing liquid stored during the polishing process. After starting the liquid suction pump, the polishing liquid flows back into the liquid storage tank through the liquid suction pipe, replenishing the polishing liquid in the liquid storage tank and realizing the recycling of the polishing liquid, greatly increasing the utilization rate of the solution polishing.

[0075] The present invention also provides a polishing method for a small-diameter groove heat pipe strong cavitation composite polishing device, including the following steps:

[0076] Step 1: Install each device of the composite polishing device and adjust the relative positions of the nozzle 10 and the groove heat pipe 11 through the polishing fixture 16;

[0077] Step 2: Start the stirrer 2 to stir the polishing liquid stored in the liquid storage tank 1. During the polishing process, the stirrer 2 continuously stirs to keep the abrasive grains evenly dispersed in the solution;

[0078] Step 3: Start the driving motor 6, which drives the rotating shaft 8 to rotate through the coupling 7. The rotating shaft 8 is clamped by the rotating fixture 9 to drive the nozzle 10 to rotate stably;

[0079] Step 4: Start the ultrasonic device, and apply the generated ultrasonic vibration to the entire groove heat pipe 11 through the ultrasonic platform 14;

[0080] Step 5: Start the air suction pump 13. The air suction pump 13 extracts the air in the sealed cavity 15 through the air suction pipe 12, observes the internal pressure of the cavity through the pressure valve, and makes it reach a vacuum degree of -2, so as to form a negative pressure environment in the sealed cavity 15. There is a high pressure difference at the nozzle 10, driving the polishing liquid to flow from the liquid storage tank 1 to the nozzle 10;

[0081] Step 6: Start the liquid suction pump 3, increase the liquid flow rate by pressurizing the liquid suction pump 3. The polishing liquid enters the rotating shaft 8 through the liquid suction pipe 4 under the action of the liquid suction pump 3, then enters the five-stage variable-diameter nozzle, and finally sprays out at high speed in a rotating manner, so that the polishing liquid rotates and sprays on the inner surface of the groove heat pipe 11 to realize the composite polishing of the groove heat pipe 11;

[0082] Step 7: During the polishing process, start the liquid suction pump I 20 to return the polishing liquid during the polishing process to the liquid storage tank through the liquid suction pipe I 21, and recycle the polishing liquid.

[0083] Embodiment 2

[0084] As Figure 3As shown, a small-diameter grooved heat pipe strong cavitation composite polishing device increases the length of the liquid suction pipe 4. The liquid suction pipe 4 is changed from entering from one side of the liquid storage tank 1 to entering from the top, reducing the volume of the sealing cavity 15. A smaller volume of the sealing cavity 15 is more conducive to adjusting the air pressure in the cavity, making the device more stable and smaller in size. The device structures and processing methods of other parts are the same as those in Embodiment 1.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A small-diameter grooved heat pipe strong cavitation composite polishing device, characterized in that, it includes: a liquid suction pipe (4), a vacuum structure, a sealed cavity (15), a liquid storage tank (1) placed outside the sealed cavity (15), and a driving mechanism, a nozzle (10), a polishing fixture (16), a fixture base (18) and an ultrasonic device placed inside the sealed cavity (15). The grooved heat pipe (11) is fixed on the polishing fixture (16), the polishing fixture (16) is placed on the fixture base (18), and the fixture base (18) is fixed at the bottom of the sealed cavity (15); the liquid storage tank (1) contains polishing liquid inside. One end of the liquid suction pipe (4) extends into the liquid storage tank (1), and the other end is inserted into the sealed cavity (15) and connected to the nozzle (10) to transport the polishing liquid in the liquid storage tank (1) to the nozzle (10) for polishing the inside of the grooved heat pipe (11). The liquid suction pipe (4) and the sealed cavity (15) are sealed and connected through a sealing ring (19); the driving mechanism is connected to the nozzle (10) to realize the rotation of the nozzle (10); the vacuum structure is sealed and connected to the sealed cavity (15) to pump out the air inside the sealed cavity (15); the nozzle (10) is a five-stage variable-diameter nozzle structure. The injection port of the nozzle (10) enters the grooved heat pipe (11), and the injection port is in close contact with the grooved heat pipe (11) to ensure the sealing performance of the connection; the driving mechanism includes a motor support platform (5), a driving motor (6), a coupling (7) and a rotating shaft (8). The motor support platform (5) is fixed on one side of the sealed cavity (15) to support and fix the driving motor (6). The driving motor (6) is connected to the rotating shaft (8) through the coupling (7) to drive the rotating shaft (8) to drive the nozzle (10) to rotate. A rotating fixture (9) is arranged outside the rotating shaft (8), and the rotating fixture (9) is fixed on the polishing fixture (16) to adjust the relative position between the heat pipe and the nozzle (10) through the polishing fixture (16); by the rotational movement of the nozzle (10) with the driving motor (6), the movement trajectory of the abrasive grains in the polishing liquid is changed, and the movement trajectory of the abrasive grains is a composite movement of rotational movement and linear movement; the vacuum structure includes an air suction pipe (12) and an air suction pump (13) arranged on the air suction pipe (12). The air suction pump (13) is located outside the sealed cavity (15). One end of the air suction pipe (12) is inserted into the sealed cavity (15). After the air suction pump (13) works, the vacuum degree inside the sealed cavity (15) reaches -2; after the air suction pump (13) is started, the air inside the sealed cavity (15) is pumped out, so that the internal pressure P1 of the sealed cavity (15) is much lower than the atmospheric pressure P2 outside the sealed cavity (15). As the connection channel inside and outside the cavity, a high pressure difference will be formed inside and outside the nozzle (10). Under the low-pressure suction effect, the polishing liquid flows to the nozzle (10) at a certain speed through the liquid suction pipe (4).

2. The small-diameter grooved heat pipe strong cavitation composite polishing device according to claim 1, characterized in that, The polishing liquid is an abrasive polishing liquid, comprising silicon dioxide abrasives, a stabilizer and a water-based liquid. The mass fraction of the silicon dioxide abrasives is 10-20%, the particle size is 0.5-10 μm, and the mass fraction of the stabilizer is 5%.

3. The strong cavitation composite polishing device for small-diameter groove heat pipe according to claim 1, It is characterized in that The ultrasonic device comprises an ultrasonic platform (14) and an ultrasonic generator (17); the grooved heat pipe (11) is located on the ultrasonic platform (14); the ultrasonic platform (14) is fixed on a polishing fixture (16); and the ultrasonic generator (17) is connected to the ultrasonic platform (14) and is used to provide energy to the ultrasonic platform (14) to build an ultrasonic polishing platform.

4. The strong cavitation composite polishing device for small-diameter groove heat pipe according to claim 1, It is characterized in that The air intake pipe (12) and the sealed cavity (15) are sealed and connected via a sealing ring (19).

5. The strong cavitation composite polishing device for small-diameter groove heat pipe according to claim 1, It is characterized in that The liquid suction pipe (4) is connected to a side wall of the liquid storage tank (1) or the top of the liquid storage tank (1); a liquid suction pump (3) is also provided on the liquid suction pipe (4), and the liquid suction pump (3) is located outside the sealed cavity (15) and is used to increase the pressure of the polishing liquid so that the pressure difference at the nozzle (10) reaches 0.6-0.8 MPa, thereby increasing the flow rate of the polishing liquid. When the polishing liquid flows through the five-step variable diameter nozzle, the nozzle (10) gradually decreases in diameter, and the final jet velocity is 1-2 m / s.

6. The strong cavitation composite polishing device for small-diameter groove heat pipe according to claim 1 or 2, It is characterized in that The liquid storage tank (1) is provided with a stirrer (2), and the stirrer (2) fully stirs the liquid storage tank (1) to achieve full mixing of the abrasive particles and the aqueous solution in the polishing liquid. During the polishing process, the stirrer (2) continuously stirs to ensure that the abrasive particles are evenly dispersed.

7. The strong cavitation composite polishing device for small-diameter groove heat pipe according to claim 1, It is characterized in that A liquid suction pipe I (21) and a liquid suction pump I (20) are also provided at the bottom of the sealed cavity (15). The liquid suction pump I (20) is arranged on the liquid suction pipe I (21) and is located outside the sealed cavity (15). One end of the liquid suction pipe I (21) is located at the bottom end of the sealed cavity (15), and the other end extends out and is inserted into the liquid storage tank (1). The polishing liquid at the bottom of the sealed cavity (15) is returned to the liquid storage tank (1) through the liquid suction pipe I (21) (4) and the liquid suction pump I (20), so as to realize the recycling of the polishing liquid. The liquid suction pipe I (21) and the sealed cavity (15) are sealed and connected via a sealing ring (19).

8. A polishing method for a small-diameter groove heat pipe strong cavitation composite polishing device as claimed in any one of claims 1 to 7, It is characterized in that The steps include: Step 1: Install each device of the composite polishing device, and adjust the relative position of the nozzle (10) and the groove heat pipe (11) by means of a polishing fixture (16); Step 2: Start the mixer (2) to stir the polishing liquid stored in the liquid storage tank (1). During the polishing process, the mixer (2) keeps stirring continuously to ensure that the abrasive grains are evenly dispersed in the solution; Step 3: Start the drive motor (6), which drives the rotating shaft (8) to rotate through the coupling (7). The rotating shaft (8), under the clamping of the rotating fixture (9), drives the nozzle (10) to rotate stably; Step 4: Start the ultrasonic device, and the ultrasonic vibration generated acts on the entire grooved heat pipe (11) through the ultrasonic platform (14); Step 5: Start the suction pump (13). The suction pump (13) extracts the air in the sealed cavity (15) through the suction pipe (12). Observe the internal pressure of the cavity through the pressure valve to make it reach a vacuum degree of -2, so as to form a negative pressure environment in the sealed cavity (15). There is a high pressure difference at the nozzle (10), which drives the polishing liquid to flow from the liquid storage tank (1) to the nozzle (10); Step 6: Start the liquid suction pump (3). Increase the liquid flow rate by pressurizing the liquid suction pump (3). The polishing liquid enters the rotating shaft (8) through the liquid suction pipe (4) under the action of the liquid suction pump (3), then enters the five-stage variable-diameter nozzle, and finally sprays out at high speed in a rotating manner, so that the polishing liquid rotates and sprays on the inner surface of the grooved heat pipe (11) to achieve the composite polishing of the grooved heat pipe (11); Step 7: During the polishing process, start the liquid suction pump I (20) to return the polishing liquid during the polishing process to the liquid storage tank through the liquid suction pipe I (21) for recycling the polishing liquid.

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