A deep controllable complex micro-hole inner surface strengthening device and method

Abstract

The application discloses a deep controllable complex micro-hole inner surface strengthening device and method, a nozzle has a high-pressure nozzle and four low-pressure nozzles, the four low-pressure nozzles are uniformly arranged in the circumferential direction outside the high-pressure nozzle, a water reservoir one outlet is sequentially connected with a high-pressure plunger pump inlet through a pipeline, a first valve and a filter, a high-pressure plunger pump outlet is connected with a high-pressure nozzle through a pipeline, a pressure relief valve and a first pressure gauge, and forms a high-pressure pipeline, the high-pressure plunger pump is electrically connected with a motor and a frequency converter five in sequence; water and abrasive particles are stored in a water reservoir two, the water reservoir two has four outlets, each outlet is connected with a corresponding low-pressure nozzle through a corresponding valve, a centrifugal pump and a pressure gauge, and four low-pressure pipelines are formed, and each centrifugal pump is electrically connected with a frequency converter; the incident pressure entering the high-pressure nozzle and the low-pressure nozzle is controlled by adjusting the frequency converters in the high-pressure pipeline and the low-pressure pipeline, and different depth regions of the micro-hole inner surface are strengthened.

Description

Technical Field

[0001] This invention relates to the field of strengthening the inner surface of micro-through holes, and more specifically to a processing technology that uses artificial submerged cavitation jets carrying abrasives to strengthen the inner surface of micro-through holes. Background Technology

[0002] Micro-through holes, widely used in everyday life, typically have small diameters and large length-to-diameter ratios, and some even have complex shapes, such as curved areas. With the rapid development of industries like electronics and information, the requirements for precision and strength of machine parts in industrial production are gradually increasing. Strengthening processing technology for micro-through holes has always been a challenge, and existing strengthening techniques still face difficulties in meeting the different depths, areas, and surface treatment requirements of complex-shaped micro-through holes.

[0003] Cavitation water jet technology utilizes the enormous energy generated by the collapse of cavitation bubbles in a liquid for material strengthening, making it an effective method for strengthening micro-holes. Compared to traditional strengthening techniques, cavitation water jet technology is more controllable, more environmentally friendly, and lower in cost. Most existing cavitation water jet technologies are artificially submerged, such as the Chinese patent with patent number ZL201810562060.0, entitled "An Apparatus and Method for Artificially Submerged Cavitation Jet Plastic Forming of Micro-parts." However, these cavitation water jet technologies suffer from a small effective target distance and, due to limitations in operating conditions (requiring a liquid environment), cannot process micro-holes attached to large parts due to size constraints. Artificial submerged cavitation jet technology, as described in Chinese Patent No. 202210961025.2 (titled "A Non-Submerged Ultrasonic Cavitation-Assisted Water Jet Nozzle Structure"), involves adding a sleeve around a conventional cavitation nozzle. By introducing a low-velocity jet into the outer sleeve, a submerged environment is created for the high-velocity jet ejected from the internal cavitation nozzle. This induces a shearing effect between the high-velocity and low-velocity jets, forming a low-pressure zone. When the pressure falls below the saturated vapor pressure, cavitation occurs, generating a cavitation jet. This cavitation jet technology effectively overcomes the limitations of submerged cavitation water jets. However, challenges remain, such as controlling the depth and region of micro-holes to enhance cavitation jets and improving processing efficiency in complex shapes. Summary of the Invention

[0004] To overcome the limitations of existing artificial submerged cavitation water jet strengthening processes for the inner surface of micro-holes, such as processing constraints, inability to process different areas in segments, and low strengthening efficiency in complex shaped areas, this invention innovatively proposes a novel depth-controllable device and method for strengthening the inner surface of complex micro-holes. This method achieves strengthening of the inner surface of micro-holes at various depths and in curved areas, improving the continuity, uniformity, and strengthening efficiency of the micro-hole inner surface strengthening process.

[0005] To achieve the above objectives, the technical solution of the depth-controllable complex micro-hole internal surface strengthening device of the present invention is as follows: it has a water storage tank I, a water storage tank II, and a nozzle. The nozzle has one high-pressure nozzle and four low-pressure nozzles. The high-pressure nozzle is located at the center of the nozzle, and the four low-pressure nozzles have the same structure and are evenly arranged circumferentially outside the high-pressure nozzle. The water storage tank I contains water. The outlet of the water storage tank I is connected to the inlet of the high-pressure plunger pump via a pipeline, passing through a first valve and a filter. The outlet of the high-pressure plunger pump is connected to the high-pressure nozzle via a pipeline, passing through a pressure relief valve and a first pressure gauge, forming a high-pressure pipeline. The high-pressure plunger pump... The secondary electrical connection is to the motor and frequency converter five; the second water tank contains water and abrasive particles, and has four outlets. Each outlet is connected to a corresponding low-pressure nozzle via a valve, a centrifugal pump, and a pressure gauge, forming four low-pressure pipelines; each centrifugal pump is electrically connected to a frequency converter; the nozzle is placed above the transparent water tank via a nozzle clamp, and the micro-hole of the workpiece to be processed is placed between the transparent water tank and the nozzle via a workpiece clamp, ensuring that the highest water level in the transparent water tank does not contact the micro-hole; the frequency converter five and the four frequency converters in the low-pressure pipeline are adjusted to control the speed of the high-pressure plunger pump and each centrifugal pump, processing different depth areas on the inner surface of the micro-hole.

[0006] Optimized solution: The high-pressure nozzle, near the micro-through hole, consists of a continuous converging section, a cylindrical section, and an expanding section from top to bottom. The diameter of the converging section gradually decreases from top to bottom. The diameter of the cylindrical section is the same as the lower end diameter of the converging section. The diameter of the expanding section gradually increases from top to bottom. The lower sections of the four low-pressure nozzles gradually converge towards the high-pressure nozzle from top to bottom, forming a cone shape.

[0007] The technical solution adopted by the strengthening method of the micro-through-hole inner surface strengthening device is as follows:

[0008] When the front face region of the micro-through hole is strengthened, the speed of the high-pressure plunger pump and the four centrifugal pumps is reduced at the same time, so that the cavitation water jet carrying abrasive particles is shortened.

[0009] When the rear end face region of the micro-hole is strengthened, the speed of the high-pressure plunger pump and the four centrifugal pumps is increased at the same time, so that the cavitation water jet carrying abrasive particles has a longer stroke.

[0010] When strengthening the curved region of the micro-through hole, keep the fluid velocity in the high-pressure nozzle constant, reduce the fluid velocity of the low-pressure nozzle corresponding to the region with a larger bending radius, and increase the fluid velocity of the low-pressure nozzle corresponding to the region with a smaller bending radius, so that the velocity difference between the low-speed jet and the high-speed jet on the side with a larger bending radius is greater than the velocity difference between the low-speed jet and the high-speed jet on the side with a smaller bending radius.

[0011] The initial pressure of the high-speed jet entering the high-pressure nozzle is at least 20 MPa, and the initial pressure does not exceed 1000 times the low-speed jet pressure of the low-pressure nozzle.

[0012] Optimization solution: When the front end face area of ​​the micro-through hole is strengthened, the high-speed jet injection pressure entering the high-pressure nozzle (23) is reduced to half of the initial pressure when the rotation speed of the high-pressure plunger pump is reduced.

[0013] Further optimization: When the rear end face region of the micro-through hole is strengthened, the injection pressure of the high-speed jet entering the high-pressure nozzle increases to 1.5 times the initial pressure.

[0014] Further optimization: When reinforcing the curved region of the micro-orifice, the jet injection pressure of the low-pressure nozzle corresponding to the side with the larger curved radius is the lowest, while the jet injection pressure of the low-pressure nozzle corresponding to the opposite side with the smaller curved radius is the highest. The jet injection pressures of the other two low-pressure nozzles are the same.

[0015] Compared with the prior art, the present invention has the following outstanding advantages:

[0016] (1) The nozzle and micro-holes in this invention do not need to be submerged in water. Under the combined action of high temperature and high pressure generated by cavitation collapse and continuous impact of abrasive particles, the inner surface of the micro-holes is strengthened. This solves the problem that when using artificial submerged cavitation water jet technology to strengthen the inner surface of micro-holes, only a single area can be strengthened and the strengthening efficiency of curved areas is low.

[0017] (2) This invention controls the speed of the high-pressure plunger pump in the high-pressure pipeline and the centrifugal pump in the low-pressure pipeline by adjusting the frequency converter in the high-pressure and low-pressure pipelines, thereby controlling the injection pressure of the fluid entering the high-pressure nozzle and the low-pressure nozzle, thereby controlling the stroke of the cavitation bubble in the jet during the initial generation, development, shedding and collapse stages, so that the cavitation bubble collapses at different depths on the inner surface of the micro-through hole, thereby achieving the purpose of strengthening the processing of different depth areas on the inner surface of the micro-through hole.

[0018] (3) This invention controls the speed of the centrifugal pump in the low-pressure pipeline by adjusting the frequency converter in the low-pressure pipeline, thereby controlling the injection pressure of the fluid entering the low-pressure nozzle. This makes the flow velocities of the low-speed jets on both sides of the micro-hole unequal, and the shearing action between them unequal. As a result, the number of cavitation bubbles collapsing on the side with a larger surface area of ​​the micro-hole is greater than that on the side with a smaller surface area, thereby strengthening the curved area of ​​the micro-hole. This improves the continuity, uniformity and strengthening efficiency of the strengthening treatment of the micro-hole surface. The difference in the number of cavitation bubbles collapsing at the front and rear ends of the micro-hole surface and the difference in the number of cavitation bubbles collapsing due to the surface pressure difference in the curved area of ​​the micro-hole strengthens different areas of the micro-hole surface and improves the strengthening efficiency of the curved area. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0020] Figure 1 This is a schematic diagram of the overall structure of a depth-controllable complex micro-hole inner surface strengthening device according to the present invention.

[0021] Figure 2 yes Figure 1 A magnified isometric view of the nozzle;

[0022] Figure 3 yes Figure 2 Axonometric view of the nozzle structure from below;

[0023] Figure 4 yes Figure 3 A cross-sectional view of the nozzle and a diagram showing the fluid entering the nozzle;

[0024] Figure 5 This is a schematic diagram of the front face area of ​​the nozzle processing the micro-through hole;

[0025] Figure 6 This is a schematic diagram of the rear cross-section area after the nozzle is processed into a micro-through hole;

[0026] Figure 7 This is a schematic diagram of the curved area of ​​a nozzle machining a micro-through hole.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. Water storage tank one; 2. Valve; 3. Filter; 4. Frequency converter five; 5. Motor; 6. High-pressure plunger pump; 7. Pressure relief valve; 8. Pressure gauge; 9. Water storage tank two; 10. Centrifugal pump; 11. Frequency converter one; 12. Frequency converter two; 13. Frequency converter three; 14. Frequency converter four; 15. Nozzle; 16. Stirring device; 17. Transparent water tank; 18. Water storage tank three; 19. Workpiece fixture; 20. Micro-through hole; 21. Nozzle fixture; 22. Abrasive grain; 23. High-pressure nozzle; 24. Low-pressure nozzle one; 25. Low-pressure nozzle two; 26. Low-pressure nozzle three; 27. Low-pressure nozzle four; 28. Cavitation; 231. Contraction section; 232. Cylindrical section; 233. Expansion section. Detailed Implementation

[0029] See Figure 1 The present invention discloses a depth-controllable complex micro-hole internal surface strengthening device, comprising a water storage tank 1, a valve 2, a filter 3, a frequency converter 5 4, a motor 5, a high-pressure plunger pump 6, a pressure relief valve 7, a pressure gauge 8, a water storage tank 2 9, a centrifugal pump 10, a frequency converter 11, a frequency converter 2 12, a frequency converter 3 13, a frequency converter 4 14, a nozzle 15, a stirring device 16, a transparent water tank 17, a water storage tank 3 18, a clamp 19, a micro-hole 20, a nozzle clamp 21, and an abrasive 22.

[0030] The reservoir 1 stores water. The outlet of reservoir 1 is connected to the inlet of the high-pressure plunger pump 6 via a pipeline, passing through the first valve 2 and filter 3. The high-pressure plunger pump 6 is electrically connected to the motor 5 and frequency converter 4. The motor 5 drives the pump to provide high pressure, and the frequency converter 4 regulates its speed. The outlet of the high-pressure plunger pump 6 is connected to the nozzle 15 via a pipeline, passing through the pressure relief valve 7 and the first pressure gauge 8. The pressure relief valve 7 prevents excessive pressure in the high-pressure pipeline, and the filter 3 prevents impurities from entering.

[0031] See Figure 2 and Figure 3 The nozzle 15 has five nozzles: one high-pressure nozzle and four low-pressure nozzles, namely, high-pressure nozzle 23, low-pressure nozzle one 24, low-pressure nozzle two 25, low-pressure nozzle three 26, and low-pressure nozzle four 27. The high-pressure nozzle 23 is located at the center of the nozzle 15. The four low-pressure nozzles have the same structure and are evenly arranged circumferentially outside the high-pressure nozzle 23. Low-pressure nozzle one 24 and low-pressure nozzle three 26 are opposite each other and are symmetrical with respect to the center of the high-pressure nozzle 23; low-pressure nozzle two 25 and low-pressure nozzle four 27 are opposite each other and are symmetrical with respect to the center of the high-pressure nozzle 23.

[0032] The outlet of the high-pressure plunger pump 6 is connected to the high-pressure nozzle 23 of the nozzle 15 via a pipeline through a pressure relief valve 7 and a pressure gauge 8. A high-pressure pipeline is formed by sequentially connecting the water storage tank 1, the first valve 2, the filter 3, the high-pressure plunger pump 6, the pressure relief valve 7, the pressure gauge 8, and the high-pressure nozzle 23. The high-pressure pipeline is supplied with fluid from the water storage tank 1, and the fluid medium is water. The high-pressure pipeline is supplied with high pressure by the high-pressure plunger pump 6, which is driven by a motor 5, and its speed is adjusted by a frequency converter 4. Valve 2 controls the opening and closing of the first valve 2. The filter 3 filters and removes impurities from the fluid in the water storage tank 1. The pressure gauge 8 is used to detect the pressure in the high-pressure pipeline. The pressure relief valve 7 protects the pressure in the high-pressure pipeline within a set pressure range. The pipes in the high-pressure pipeline are high-pressure hoses.

[0033] Water storage tank 2 (9) has four outlets. Each outlet is connected to a corresponding low-pressure nozzle on nozzle 15 via a valve, a centrifugal pump 10, and a pressure gauge. Water storage tank 2 (9), valves, centrifugal pumps 10, pressure gauges, and low-pressure nozzles form a low-pressure pipeline, resulting in four low-pressure pipelines in total. Each centrifugal pump 10 is electrically connected to a frequency converter. Water storage tank 2 (9) stores water and abrasive particles 22 as the medium fluid. A stirring device 16 is installed in water storage tank 2 (9) to uniformly mix the water and abrasive particles 22. The fluid in all four low-pressure pipelines is supplied by water storage tank 2 (9). The speed of the first low-pressure pipeline (I) is regulated by frequency converter 1 (11), the second low-pressure pipeline (II) by frequency converter 2 (12), the third low-pressure pipeline (III) by frequency converter 3 (13), and the fourth low-pressure pipeline (IV) by frequency converter 4 (14).

[0034] All pipes in the four low-pressure pipelines are corrugated pipes. By adjusting frequency converters 5 (4), 11 (11), 2 (12), 3 (13), and 4 (14), the speeds of the high-pressure plunger pump 6 and the centrifugal pump 10 are controlled, thereby controlling the injection pressure of the fluid entering the high-pressure nozzle 23, low-pressure nozzle 1 (24), low-pressure nozzle 2 (25), low-pressure nozzle 3 (26), and low-pressure nozzle 4 (27).

[0035] Nozzle 15 is positioned above transparent water tank 17 via nozzle clamp 21. The micro-hole 20 of the workpiece to be processed is positioned between transparent water tank 17 and nozzle 15 via workpiece clamp 19. The central axis of the front end of the micro-hole 20 to be processed is collinear with the central axis of nozzle 15 (in this invention, the front end of the micro-hole 20 to be processed is positioned upwards). The highest water level in transparent water tank 17 must not touch the micro-hole 20 and should be below the bottom surface of the micro-hole 20. The water in transparent water tank 17 prevents splashing of fluid ejected from nozzle 15. Transparent water tank 17 is connected to water storage tank 3 18 via a pipe, and the fluid in transparent water tank 17 enters water storage tank 3 18.

[0036] See Figure 4The high-pressure nozzle 23, near the micro-through hole 20, consists of a continuous converging section 231, a cylindrical section 232, and an expanding section 233 from top to bottom. The diameter of the converging section 231 gradually decreases from top to bottom, the diameter of the cylindrical section 232 is the same as the lower diameter of the converging section 231, and the diameter of the expanding section 233 gradually increases from top to bottom. The lower sections of the four low-pressure nozzles gradually converge towards the high-pressure nozzle 23 at the center, forming a conical structure.

[0037] When the inner surface of the micro-through hole 20 is strengthened, the outlet of the nozzle 15 is collinear with the central axis of the inlet of the micro-through hole 20. High-pressure, high-speed water flows through the high-pressure pipeline to the high-pressure nozzle 23, and low-pressure, low-speed water flows through four low-pressure pipelines to low-pressure nozzle 1 24, low-pressure nozzle 25, low-pressure nozzle 3 26, and low-pressure nozzle 4 27 respectively. Due to the large velocity gradient between the two jets, a violent shearing action occurs, forming a low-pressure zone under the action of shearing force. When the pressure in this zone is lower than the saturated vapor pressure of the environment, cavitation occurs, and the cavitation bubbles collapse to generate high temperature and high pressure, which together with the abrasive particles 22 carried in the low-speed jet act on the inner surface of the micro-through hole 20. By controlling the frequency converter 54 in the high-pressure pipeline and the frequency converters 11, 212, 313 and 414 in the low-pressure pipeline, the speed of the high-pressure plunger pump 6 in the high-pressure pipeline and the centrifugal pumps 10 in the four low-pressure pipelines are controlled. This controls the injection pressure of the fluid entering the high-pressure nozzle 23 and the low-pressure nozzles 124, 25, 326 and 427, and ultimately controls the stroke of the cavitation bubble in its initial, development, shedding and collapse stages, thereby achieving the purpose of strengthening the processing of different depth areas on the inner surface of the micro-through hole 20. By using frequency converters 11, 12, 13, and 14, the rotational speed of centrifugal pumps 10 in the four low-pressure pipelines is controlled, thereby controlling the injection pressure of the fluid entering the low-pressure nozzles 24, 25, 26, and 27. This causes the flow velocities of the low-speed jets on both sides of the micro-through hole 20 to be unequal, resulting in unequal shearing action between the low-speed and high-speed jets on both sides. Consequently, the number of cavitation bubbles collapsing on the side with a larger surface area inside the micro-through hole 20 is greater than that on the side with a smaller surface area, thus achieving the purpose of strengthening the curved area of ​​the inner surface of the micro-through hole 20.

[0038] In this invention, each of the high-pressure and low-pressure nozzles in the nozzle 15 corresponds to a pipeline: the high-pressure nozzle corresponds to the high-pressure pipeline, and the four low-pressure nozzles correspond to the four low-pressure pipelines. By adjusting the frequency converters in the high-pressure and low-pressure pipelines, the rotational speeds of the high-pressure plunger pump 6 in the high-pressure pipeline and the centrifugal pump 10 in the low-pressure pipeline are controlled, thereby controlling the injection pressure of the fluid entering the high-pressure and low-pressure nozzles. This achieves the purpose of processing different depth areas on the inner surface of the micro-through hole 20 and improving the processing efficiency of the curved area. When strengthening the front end face area of ​​the micro-through hole 20, the frequency converters in the high-pressure and low-pressure pipelines are adjusted, and the rotational speeds of the high-pressure plunger pump 6 and the four centrifugal pumps 10 are reduced, thereby reducing the injection pressure of the fluid entering the high-pressure and low-pressure nozzles. This shortens the stroke of the cavitation water jet carrying the abrasive particles 22, causing the cavitation bubbles to collapse in the front end face area of ​​the micro-through hole 20. The resulting high pressure and high temperature, together with the abrasive particles 22, act on the micro-through hole 20, strengthening the front end face area of ​​the micro-through hole 20. When strengthening the rear end face region of the micro-hole, the frequency converter in the high and low pressure pipeline is adjusted, and the speed of the high pressure plunger pump 6 and the four centrifugal pumps 10 is increased at the same time. This increases the injection pressure of the fluid entering the high pressure nozzle and the low pressure nozzle, making the cavitation water jet carrying the abrasive particles 22 longer. The cavitation bubbles 28 collapse in the rear end face region of the micro-hole 20. The high pressure and high temperature generated by the collapse, together with the abrasive particles 22, act on the micro-hole 20, strengthening the rear end face region of the micro-hole 20. When strengthening the curved region of the micro-through hole, the fluid velocity in the high-pressure nozzle 23 is kept constant. On the one hand, the abrasive particles 22 carried by the low-speed water flow around the high-pressure nozzle 23 continuously impact the inner surface of the curved region of the micro-through hole 20. On the other hand, by reducing the fluid velocity of the low-pressure nozzle corresponding to the side with a larger bending radius of the curved region of the micro-through hole 20 and increasing the fluid velocity of the low-pressure nozzle corresponding to the side with a smaller bending radius of the curved region of the micro-through hole 20, the velocity of the low-speed jet at the side with a larger bending radius is less than that at the side with a smaller bending radius. At this time, the velocity difference between the low-speed jet and the high-speed jet at the side with a larger bending radius is greater than that at the side with a smaller bending radius. Therefore, the shearing effect between the low-speed jet and the high-speed jet at the side with a larger bending radius is stronger than that between the low-speed jet and the high-speed jet at the side with a smaller bending radius. As a result, the number of cavitation collapses at the larger area of ​​the curved region with a larger bending radius is greater than that at the smaller area of ​​the curved region with a smaller bending radius, thereby improving the processing efficiency of strengthening the curved region of the micro-through hole 20.

[0039] The following are three examples of the enhancement method:

[0040] Example 1:

[0041] like Figure 5As shown, when it is necessary to strengthen the front face area of ​​the micro-through hole 20, the front face area is the area near the nozzle 15. Open all valves 2 in the high-pressure and low-pressure pipelines. The high-pressure plunger pump 6 and centrifugal pump 10 provide high and low pressure to the high-pressure and low-pressure pipelines respectively. The fluids in reservoir 1 and reservoir 2 9 enter the high-pressure nozzle 23, low-pressure nozzle 1 24, low-pressure nozzle 2 25, low-pressure nozzle 3 26, and low-pressure nozzle 4 27 respectively through the high-pressure pipeline, low-pressure pipeline I, low-pressure pipeline II, low-pressure pipeline III, and low-pressure pipeline IV. Adjust the frequency converter 5 4 to ensure that the injection pressure of the high-speed jet entering the high-pressure nozzle 23 is at least 20 MPa; this pressure is the initial pressure. Adjust inverters 11, 12, 13, and 14 to ensure that the low-velocity jet injection pressure entering low-pressure nozzles 24, 25, 26, and 27 is 0.05 MPa. The initial pressure of the high-velocity jet injection in high-pressure nozzle 23 shall not exceed 1000 times the low-velocity jet injection pressure of the low-pressure nozzle. The micro-through-hole 20 is approximately 70 mm long and has an inner diameter of approximately 35 mm. The nozzle 15 has an inner diameter of approximately 30 mm, and the inner diameter of the micro-through-hole 20 must be slightly larger than that of the nozzle 15. In high-pressure nozzle 23, the contraction section is approximately 4 mm long with a contraction angle of approximately 40°, the cylindrical section is approximately 7 mm long, and the expansion section is approximately 4 mm long with an expansion angle of approximately 60°. When strengthening the front face region of the micro-via 20, on the one hand, the low-pressure water carries abrasive particles 22. Under the continuous impact of the abrasive particles 22, the dislocation density in the plastic deformation layer of the micro-via 20 increases and the grain size is refined, thus achieving the purpose of strengthening the front face region of the micro-via 20. On the other hand, the frequency converter 4 is adjusted to reduce the injection pressure of the high-speed jet entering the high-pressure nozzle 23 by half to 10 MPa. When the high-speed jet receives a reduced injection pressure, the velocity gradient between the high-speed jet and the low-speed jet decreases, thus weakening the shearing effect and reducing the range of the local low-pressure zone in the liquid. The cavitation nuclei undergo a process of initiation and development, forming a cavitation cloud that moves downstream with the high-speed jet. When the pressure around the cavitation cloud recovers, the cavitation group within it will collapse in a concentrated manner. Due to the reduction in the low-pressure area, the distance from the nozzle outlet to the collapse of the cavitation group becomes shorter, meaning the journey from the formation to the collapse of the cavitation bubble 28 is shortened. The collapse of the cavitation bubble in the front face region of the micro-through hole 20 generates high temperature and high pressure, thereby achieving the purpose of strengthening the front face region of the micro-through hole 20.

[0042] Example 2:

[0043] like Figure 6As shown, when it is necessary to strengthen the rear end face area of ​​the micro-through hole 20, all valves 2 in the high-pressure and low-pressure pipelines are opened. The high-pressure plunger pump 6 and centrifugal pump 10 provide high pressure and low pressure to the high-pressure and low-pressure pipelines, respectively. The fluids in reservoir 1 and reservoir 2 9 enter the high-pressure nozzle 23, low-pressure nozzle 1 24, low-pressure nozzle 25, low-pressure nozzle 3 26, and low-pressure nozzle 4 27 through the high-pressure pipeline, low-pressure pipeline I, low-pressure pipeline II, low-pressure pipeline III, and low-pressure pipeline IV, respectively. Adjust the frequency converter 5 4 so that the initial injection pressure of the high-speed jet entering the high-pressure nozzle 23 is 20 MPa. Adjust the frequency converters 1 11, 2 12, 3 13, and 4 14 so that the injection pressure of the low-speed jet entering the low-pressure nozzle 1 24, low-pressure nozzle 25, low-pressure nozzle 3 26, and low-pressure nozzle 4 27 is 0.05 MPa. The micro-orifice 20 is approximately 70 mm long and has an inner diameter of approximately 35 mm. The nozzle 15 has an inner diameter of approximately 30 mm, and the inner diameter of the micro-orifice 20 needs to be slightly larger than that of the nozzle 15. In the high-pressure nozzle 23, the contraction section is approximately 4 mm long with a contraction angle of approximately 40°, the cylindrical section is approximately 7 mm long, and the expansion section is approximately 4 mm long with an expansion angle of approximately 60°. When strengthening the rear end face region of the micro-orifice 20, on the one hand, the low-pressure water carries abrasive particles 22. Under the continuous impact of these abrasive particles 22, the dislocation density within the plastic deformation layer of the micro-orifice 20 increases, and the grain size becomes finer, thus achieving the purpose of strengthening the front end face region of the micro-orifice 20. On the other hand, the frequency converter 4 is adjusted so that the injection pressure of the high-speed jet entering the high-pressure nozzle 23 gradually increases from the initial pressure to 1.5 times the initial pressure of 20 MPa, reaching 30 MPa. When the high-speed jet receives an increased injection pressure, the velocity gradient between the high-speed jet and the low-speed jet increases, thus enhancing the shearing effect and increasing the range of the local low-pressure zone in the liquid. Cavitation nuclei undergo a process of initiation and development, forming a cavitation cloud that moves downstream with the high-speed jet. When the pressure around the cavitation cloud recovers, the cavitation swarm within it will collapse in a concentrated manner. Due to the increased range of the low-pressure zone, the location where the cavitation swarm collapses becomes longer from the nozzle exit, meaning the journey from the formation to the collapse of cavitation bubble 28 becomes longer. The collapse of cavitation bubble 28 in the rear end face region of the micro-through hole 20 generates high temperature and high pressure, achieving the purpose of strengthening the rear end face region of the micro-through hole 20.

[0044] Example 3:

[0045] like Figure 7As shown, when it is necessary to strengthen the curved area of ​​the micro-through hole 20, all valves 2 in the high-pressure and low-pressure pipelines are opened. The high-pressure plunger pump 6 and centrifugal pump 10 provide high pressure and low pressure to the high-pressure and low-pressure pipelines, respectively. The fluids in reservoir 1 and reservoir 2 9 enter the high-pressure nozzle 23, low-pressure nozzle 1 24, low-pressure nozzle 25, low-pressure nozzle 3 26, and low-pressure nozzle 4 27 through the high-pressure pipeline, low-pressure pipeline I, low-pressure pipeline II, low-pressure pipeline III, and low-pressure pipeline IV, respectively. Adjust the frequency converter 5 4 to make the injection pressure of the high-speed jet entering the high-pressure nozzle 23 20MPa. Adjust the frequency converters 1 11, 2 12, 3 13, and 4 14 to make the injection pressure of the low-speed jet entering the low-pressure nozzle 1 24, low-pressure nozzle 25, low-pressure nozzle 3 26, and low-pressure nozzle 4 27 0.05MPa. The inner diameter of the micro-through hole 20 is approximately 35 mm, and the inner diameter of the nozzle 15 is approximately 30 mm. The inner diameter of the micro-through hole 20 needs to be slightly larger than the inner diameter of the nozzle 15. The radius of the bending radius on the larger side A of the bending region is approximately 40 mm, and the corresponding bending radius on the smaller side B is approximately 5 mm. In the high-pressure nozzle 23, the length of the contraction section is approximately 4 mm, the contraction angle is approximately 40°, the length of the cylindrical section is approximately 7 mm, and the length of the expansion section is approximately 4 mm, the expansion angle is approximately 60°. On one hand, the low-pressure water carries abrasive particles 22. Under the continuous impact of the abrasive particles 22, the dislocation density in the plastic deformation layer of the micro-through hole 20 increases and the grain size is refined, thereby strengthening the bending region of the micro-through hole 20. On the other hand, the bending radius of the micro-through hole 20 on the larger side A is greater than the bending radius on the inner side B, reducing the injection pressure of the fluid at the low-pressure nozzle corresponding to the outer side A and increasing the injection pressure at the low-pressure nozzle corresponding to the inner side B. If the side with the larger bending radius, A, is directly opposite the low-pressure nozzle 1 24, then the side with the smaller bending radius, B, corresponds to the low-pressure nozzle 3 26. In this case, the injection pressure of the fluid entering the low-pressure nozzle 1 24 is reduced, and the injection pressure of the fluid entering the low-pressure nozzle 3 26 is increased. At this time, the injection pressure of the low-velocity jet in the nozzle 15 is: 0.08 MPa for low-pressure nozzle 3 26, 0.05 MPa for low-pressure nozzle 25, 0.02 MPa for low-pressure nozzle 4 27, and 0.02 MPa for low-pressure nozzle 1 24.If the side with the larger bending radius, A, corresponds to low-pressure nozzle 25, then the side with the smaller bending radius, B, corresponds to low-pressure nozzle 4, 27. Therefore, the injection pressure of the fluid entering low-pressure nozzle 25 is reduced, and the injection pressure of the fluid entering low-pressure nozzle 4, 27 is increased. At this time, the low-velocity jet injection pressure within nozzle 15 is: 0.08 MPa for low-pressure nozzle 4, 27; 0.05 MPa for low-pressure nozzle 1, 24; and 0.02 MPa for low-pressure nozzle 25. Similarly, if the side with the larger bending radius, A, corresponds to low-pressure nozzle 3, 26, then the side with the smaller bending radius, B, corresponds to low-pressure nozzle 1, 24. Therefore, the injection pressure of the fluid entering low-pressure nozzle 3, 26, is reduced, and the injection pressure of the fluid entering low-pressure nozzle 1, 24 is increased. At this time, the low-velocity jet injection pressure within nozzle 15 is: 0.08 MPa for low-pressure nozzle 1, 24; and 0.02 MPa for low-pressure nozzle 25. The pressure of nozzle 4 (27) is 0.05 MPa, and the pressure of low-pressure nozzle 3 (26) is 0.02 MPa. If the low-pressure nozzle 4 (27) corresponds to the side with a larger bending radius (A), then the low-pressure nozzle 2 (25) corresponds to the side with a smaller bending radius (B). The injection pressure of the fluid entering low-pressure nozzle 4 (27) is reduced, and the injection pressure of the fluid entering low-pressure nozzle 2 (25) is increased. At this time, the injection pressure of the low-velocity jet inside nozzle 15 is as follows: low-pressure nozzle 2 (25) is 0.08 MPa, low-pressure nozzle 1 (24) is equal to low-pressure nozzle 3 (26) at 0.05 MPa, and low-pressure nozzle 4 (27) at 0.02 MPa. That is, the injection pressure of low-pressure nozzle 4 (27) corresponding to the side with a larger bending radius (A) is the smallest, and the injection pressure of low-pressure nozzle 2 (25) corresponding to the side with a smaller bending radius (B) is the largest. The injection pressures of the other two low-pressure nozzles, low-pressure nozzle 1 (24) and low-pressure nozzle 3 (26), are the same.

[0046] At the side with a larger bending radius (A), the incident pressure of the low-speed jet decreases, and the velocity gradient between the low-speed and high-speed jets increases, thus enhancing the shearing effect and promoting the generation of cavitation 28. Furthermore, the reduced confining pressure of the jet enhances the interference of the high-speed jet with the surrounding fluid, further promoting the growth and development of cavitation 28. At the side with a smaller bending radius (B), the incident pressure of the low-speed jet increases, and the velocity gradient between the low-speed and high-speed jets decreases, thus enhancing the shearing effect and limiting the generation of cavitation 28. Additionally, the increased confining pressure of the jet weakens the interference of the high-speed jet with the surrounding fluid, hindering the growth and development of cavitation 28. Therefore, the number of cavitation collapses at the larger bending radius side (A) is greater than the number at the smaller bending radius side (B), achieving the goal of improving the processing efficiency of the bent region of the reinforced micro-through hole 20.

Claims

1. A device for strengthening the inner surface of complex micro-holes with controllable depth, comprising a water storage tank (1), a water storage tank (9), and a nozzle (15), characterized in that: The nozzle (15) has one high-pressure nozzle and four low-pressure nozzles. The high-pressure nozzle (23) is located at the center of the nozzle (15). The four low-pressure nozzles have the same structure and are evenly arranged around the outside of the high-pressure nozzle (23) in a circumferential direction. The first water tank (1) contains water. The outlet of the first water tank (1) is connected to the inlet of the high-pressure plunger pump (6) through a pipe via the first valve and the filter (3). The outlet of the high-pressure plunger pump (6) is connected to the high-pressure nozzle (23) through a pipe via the pressure relief valve (7) and the first pressure gauge (8), forming a high-pressure pipeline. The high-pressure plunger pump (6) is electrically connected to the motor (5) and the frequency converter (4) in sequence. The second water tank (9) contains water and abrasive particles. 22) The second reservoir (9) has four outlets. Each outlet is connected to a corresponding low-pressure nozzle via a valve, a centrifugal pump (10), and a pressure gauge, forming four low-pressure pipelines. Each centrifugal pump (10) is electrically connected to a frequency converter. The nozzle (15) is placed above the transparent water tank (17) through the nozzle clamp. The micro-hole of the workpiece to be processed is placed between the transparent water tank (17) and the nozzle (15) through the workpiece clamp. The highest water level in the transparent water tank (17) does not contact the micro-hole. Adjust the frequency converter (4) and the four frequency converters in the low-pressure pipeline to control the speed of the high-pressure plunger pump (6) and each centrifugal pump (10) to process different depth areas on the inner surface of the micro-hole.

2. The complex micro-hole internal surface strengthening device according to claim 1, characterized in that: The high-pressure nozzle (23) is composed of a continuous contraction section (231), a cylindrical section (232), and an expansion section (233) from top to bottom in the lower section near the micro-through hole (20). The diameter of the contraction section (231) gradually decreases from top to bottom. The diameter of the cylindrical section (232) is the same as the lower diameter of the contraction section (231). The diameter of the expansion section (233) gradually increases from top to bottom. The lower sections of the four low-pressure nozzles gradually contract towards the high-pressure nozzle (23) from top to bottom, forming a cone shape.

3. The complex micro-hole internal surface strengthening device according to claim 1, characterized in that: The transparent water tank (17) is connected to the reservoir three (18) via a pipe.

4. The complex micro-hole internal surface strengthening device according to claim 1, characterized in that: A stirring device (16) is installed in the second (9) reservoir.

5. The complex micro-hole internal surface strengthening device according to claim 2, characterized in that: The inner diameter of the micro-through hole is larger than the inner diameter of the nozzle (15), the contraction angle of the contraction section (231) is 40°, and the expansion angle of the expansion section (233) is 60°.

6. A strengthening method for the complex micro-hole inner surface strengthening device as described in claim 1, characterized in that: When the front face area of ​​the micro-through hole is strengthened, the speed of the high-pressure plunger pump (6) and the four centrifugal pumps (10) is reduced at the same time, so that the cavitation water jet carrying abrasive particles (22) has a shorter stroke. When the rear end face region of the micro-hole is strengthened, the rotation speed of the high-pressure plunger pump (6) and the four centrifugal pumps (10) is increased at the same time, so that the cavitation water jet carrying abrasive particles (22) has a longer stroke. When strengthening the curved region of the micro-through hole, keep the fluid velocity in the high-pressure nozzle (23) constant, reduce the fluid velocity of the low-pressure nozzle corresponding to the region with a larger bending radius in the curved region, and increase the fluid velocity of the low-pressure nozzle corresponding to the region with a smaller bending radius, so that the velocity difference between the low-speed jet and the high-speed jet at the region with a larger bending radius is greater than the velocity difference between the low-speed jet and the high-speed jet at the region with a smaller bending radius.

7. The strengthening method according to claim 6, characterized in that: The initial pressure of the high-speed jet entering the high-pressure nozzle (23) is at least 20 MPa, and the initial pressure does not exceed 1000 times the low-speed jet pressure of the low-pressure nozzle.

8. The strengthening method according to claim 7, characterized in that: When the front end face region of the micro-through hole is strengthened, the high-speed jet injection pressure entering the high-pressure nozzle (23) is reduced to half of the initial pressure when the rotational speed of the high-pressure plunger pump (6) is reduced.

9. The strengthening method according to claim 7, characterized in that: When the rear end face region of the micro-through hole is reinforced, the injection pressure of the high-speed jet entering the high-pressure nozzle (23) increases to 1.5 times the initial pressure.

10. The strengthening method according to claim 7, characterized in that: When reinforcing the curved region of the micro-through hole, the jet injection pressure of the low-pressure nozzle corresponding to the side with the larger curvature is the smallest, while the jet injection pressure of the low-pressure nozzle corresponding to the opposite side with the smaller curvature is the largest. The jet injection pressures of the other two low-pressure nozzles are the same.

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