Apparatus and method for controllable fluid polishing of complex internal flow channels
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2024-04-29
- Publication Date
- 2026-05-29
Smart Images
Figure CN118181124B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of precision fluid machining and relates to a device and method for controlling the fluid polishing intensity of the inner surface of complex flow channels by utilizing local obstruction to achieve globally uniform and controllable polishing. Background Technology
[0002] As modern high-end precision equipment tends towards miniaturization, complex flow channel parts with small diameters and curved flow characteristics are widely used in aerospace, biomedicine, and chemical engineering fields, serving functions such as sample extraction, fluid transport, and heat conduction and dissipation. Due to manufacturing methods and other reasons, the surface of the internal flow channels of workpieces manufactured by additive manufacturing and other methods is very rough and has various defects. During use, problems such as high flow resistance, liquid residue, and powder shedding are prone to occur. Therefore, polishing and other methods are needed to improve the surface quality of the internal flow channels to improve the flow characteristics of the internal fluid. However, traditional polishing methods are insufficient to meet the requirements for polishing small-sized, high aspect ratio, and complex internal flow channel parts.
[0003] Currently, the main methods for polishing the inner surfaces of complex flow channel parts include mechanical polishing, abrasive flow polishing, magnetic abrasive polishing, and electrolytic polishing. Mechanical polishing involves inserting a tool head into the inner surface of a slender tube; however, for curved flow channel surfaces, the tool head is difficult to insert and cannot easily change direction at bends. Furthermore, the size of the tool head limits mechanical polishing to polishing only large-diameter flow channels with an inner diameter of tens of millimeters. Abrasive flow polishing uses high-pressure, high-viscosity fluids, but pressure at bends in complex flow channels is severely reduced, resulting in uneven polishing before and after the bend, and abrasive particles remaining inside the flow channel are difficult to remove. Magnetic abrasive polishing uses magnets to drive magnetic particles inside the tube for polishing, but for complex flow channel parts with thick walls, magnetism cannot effectively control the magnetic particles inside the flow channel. Electrolytic polishing uses an oxidation-reduction reaction to dissolve the workpiece as the anode, but for complex flow channel parts, a cathode cannot be designed, making it impossible to polish complex flow channels.
[0004] The following are existing patents related to polishing the inner surface of complex flow channels:
[0005] Patent CN113211291A proposes a polishing device and method for the internal flow channels of additive manufacturing high-temperature alloys. Based on traditional abrasive flow, this device and method can adapt to the size of various high-temperature alloy parts for internal flow channel polishing through a special polishing device with variable space. However, it is only suitable for internal flow channel parts with simple structures. For complex flow channel parts, especially internal flow channel parts with large length-to-diameter ratio, it is easy to cause over-polishing at characteristic parts such as bends and sharp corners, resulting in thinning of the part wall thickness, uneven removal of different areas of the internal flow channel, and even scrapping of the part. At the same time, it has not solved the problems of complex equipment and difficulty in semi-fluid abrasive modulation in traditional abrasive flow polishing.
[0006] Patent CN117506692A proposes a polishing device and method for the inner surface of curved pipes. This device and method can enter the inner surface of curved pipes for polishing based on traditional abrasive polishing. However, it is only suitable for curved pipes with large curvature. For complex flow channels with small curvature and small inner diameter, it is difficult for elastic hoses and spherical polishing heads to penetrate. Moreover, the device achieves uniform polishing by reciprocating the movement of the polishing head, resulting in extremely low polishing efficiency.
[0007] Patent CN206998477U proposes a polishing machine for the inner hole of a slender tube. This device uses yarn to perform axial polishing on the inner hole of the workpiece. The yarn is clamped and fixed in sequence through a guide wheel, the inner hole of the workpiece, and a roller. The yarn drives the abrasive to move axially and radially relative to the inner hole of the workpiece, thereby polishing the inner hole. Although the yarn can enter the small inner hole, the amount of abrasive driven by the yarn is very small, and it cannot effectively polish the surface of the inner hole.
[0008] Patent CN109079590B proposes a polishing method based on magnetic field-assisted thickening of non-Newtonian fluids. It uses an external magnetic field to increase the viscosity of non-Newtonian fluids and an external polishing fluid circulation device. However, this method is mainly for polishing external surfaces. It is very difficult for high-viscosity fluids to enter complex flow channels with large length-to-diameter ratios and curved pipes.
[0009] In summary, existing polishing methods for complex flow channel structures use tools such as tool heads and yarns, which are not suitable for situations where there are bends in the flow channel and the flow channel diameter is as small as millimeters. Therefore, there is an urgent need to provide a polishing device and method for smaller diameter and more complex internal flow channels to improve the surface quality and uniformity of the flow channel. Summary of the Invention
[0010] To address the problems of existing polishing solutions, this invention provides a device and method for controllable fluid polishing of complex internal flow channels. This method can achieve uniform polishing intensity of controllable polishing on the inner surface of complex flow channel parts, improve the quality of the inner surface of the flow channel, reduce the frictional resistance of the medium inside the pipe, enhance the stability of the fluid inside the pipe, and solve the problems of limited, uneven, and inefficient polishing of the inner surface of existing complex flow channel parts.
[0011] To achieve the above objectives, the present invention provides the following technical solution:
[0012] A device for controllable fluid polishing of complex internal flow channels includes a work platform 9, fluid processing units, and controllable blocking ball units. Two fluid processing units are symmetrically installed on the left and right sides of the work platform 9. The complex flow channel, i.e., the workpiece 8, is located between the two fluid processing units, with the outlet and inlet ends of the workpiece 8 connected to the left and right fluid processing units, respectively. The controllable blocking ball units are located inside the workpiece 8, with a connector 5 connected to each end of the workpiece 8 to ensure the sealing of the entire device and to clamp and position the workpiece 8.
[0013] The fluid processing unit includes a piston 4, a piston cylinder 2, a piston rod 1, a connecting piece 5, and a piston cylinder support 3. The piston cylinder 2 is fixedly connected to the work platform 9 via the piston cylinder support 3. The piston 4 is installed inside the piston cylinder 2, and polishing fluid is poured into the cavity between the inner side of the piston 4 (the side connected to the workpiece 8) and the inner surface of the piston cylinder 2. The inner end of the piston rod 1 is fixedly connected to the piston 4, and the piston rod 1 is slidably connected to the opening at the outer end of the piston cylinder 2. The outlet at the inner end of the piston cylinder 2 is connected to one end of the workpiece 8 via the connecting piece 5.
[0014] The controllable blocking ball unit includes a blocking ball 6, two guide rings 7, an adjusting valve 10, and a traction rope 11. The traction rope 11 is located inside the workpiece 8; the blocking ball 6 is located inside the workpiece 8 and connected by the traction rope 11; the guide rings 7 are located on both sides of the blocking ball 6 and connected by the traction rope 11. To prevent the blocking ball 6 from deviating from the flow channel axis due to excessive tension in the traction rope 11, the guide rings 7 support the traction rope 11, ensuring that the center of the blocking ball 6 is located on the flow channel axis of the workpiece 8 through the two guide rings 7. The adjusting valve 10 is connected to the traction rope 11 on both sides; by adjusting the position of the adjusting valve 11, the length of the traction rope 11 on both sides of the blocking ball 6 is controlled, thereby adjusting the position of the blocking ball 6 inside the workpiece 8.
[0015] The position of the blocking ball 6 is controlled by the length of the traction rope 11 entering the inner flow channel of the workpiece 8, thereby controlling the scouring area. The diameter of the blocking ball 6 is close to but smaller than the inner flow channel diameter of the workpiece 8, forming a local blockage and polishing gap, allowing the high-pressure polishing fluid, i.e., the polishing slurry, to flow through only the gap at high speed. By changing the diameter of the polishing slurry flow area, the flow rate and pressure of the polishing slurry are increased, thereby controlling the polishing intensity and achieving controllable polishing of any area on the inner surface of complex flow channel parts. During the polishing process, based on Bernoulli's principle, high fluid velocity results in low pressure, and low or even no flow velocity results in high pressure. Therefore, the blocking ball automatically positions itself on the central axis of the flow channel in the high-speed fluid to ensure balanced pressure around it and prevents it from sticking to the inner wall. This principle ensures that the polishing intensity area is consistent throughout the radial direction of the flow channel, guaranteeing uniform polishing of the flow channel.
[0016] Furthermore, the piston 4 is slidably connected to the inner surface of the piston cylinder 2. The outlet at the inner end of the piston cylinder 2 is connected to one end of the connecting member 5, and the other end of the connecting member 5 communicates with the workpiece 8 (the other end of the connecting member is secured to one end of the workpiece by an internal buckle).
[0017] Furthermore, the distance between the traction rope 11 and the blocking ball 6 is 1-3mm.
[0018] Furthermore, the guide ring 7 is an umbrella-rib support ring structure; the outer diameter of the guide ring 7 is the same as the inner diameter of the flow channel of the workpiece 8, and the traction rope 11 passes through the center of the guide ring 7 to ensure that both ends of the blocking ball 6 are always near the central axis of the flow channel. The guide ring 7 has a small cross-sectional area, so it does not affect the fluid flow state within the flow channel of the workpiece 8.
[0019] Furthermore, the polishing medium in the polishing slurry is selected according to the workpiece material: when the workpiece 8 is made of aluminum-silicon alloy, the polishing slurry is made of silicon carbide; when the workpiece 8 is made of stainless steel, the polishing slurry is made of aluminum oxide; and when the workpiece 8 is made of cast iron, the polishing slurry is made of diamond powder.
[0020] A controlled fluid polishing method for complex internal flow channels, utilizing the aforementioned controlled fluid polishing device for complex internal flow channels, includes the following steps:
[0021] Step 1: Select a suitable polishing medium according to the material of workpiece 8 and prepare polishing liquid. Stir the prepared polishing liquid evenly and then draw it into the inner cavity of the piston cylinder 2 of the two fluid processing units.
[0022] Step 2: Connect the outlet of piston cylinder 2 to connector 5 via threaded connection. Connect the connector 5 to the inlet and outlet ends of workpiece 8 via internal snap-fit. After the entire connection is completed, check the sealing performance.
[0023] Step 3: The external push rod drives the piston rods 1 at both ends to move synchronously, ensuring that while one piston cylinder 2 ejects high-pressure polishing fluid, the other piston cylinder 2 draws in polishing fluid. Due to the partial blockage of the controllable blocking ball unit inside the workpiece 8, the polishing fluid has a low flow rate and low pressure loss before the blockage, maintaining a high-pressure state. When it passes through the blockage, the pressure is completely released, converting to high speed, which drives the abrasive particles in the polishing fluid to remove material from the inner wall surface of the workpiece 8. The polishing fluid is pushed back and forth by the piston rod 1 to wash the inner surface of the workpiece 8, thereby polishing the inner surface of the workpiece 8.
[0024] Step 4: Change the length of the traction rope 11 entering the inner flow channel by adjusting the position valve 10, and control the blocking ball 6 to produce a blocking effect in different areas of the workpiece.
[0025] Step 5: After processing is completed, stop changing the length of the traction rope 11 entering the inner flow channel, remove the workpiece 8, put it into the ultrasonic cleaner for cleaning, and at the same time use water to rinse the inner flow channel of the workpiece 8 until there is no polishing liquid residue in the flow channel.
[0026] Step 6: Inspect the processed workpiece 8. If the quality of its inner surface meets the expected target, the polishing process is complete.
[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0028] (1) The present invention utilizes a blocking ball or other tools similar in shape to the flow channel to enter the interior of a complex flow channel, without being limited by the inner diameter of the flow channel, the degree of curvature of the flow channel, or the thickness of the flow channel wall, thus realizing the accessibility of tools for any complex flow channel.
[0029] (2) The present invention utilizes local blockage to form fluid gaps, reducing the cross-sectional area of the regional flow channel. When the polishing fluid containing polishing abrasive particles passes through this region, the flow rate increases rapidly, and only this local region has a significant polishing effect, ensuring the controllability of the polishing position and polishing effect.
[0030] (3) The present invention utilizes the Bernoulli principle of fluid and the guide ring to achieve uniformity of the gap between the surrounding fluids, ensuring that the radial polishing effect of the flow channel is the same everywhere, and realizing the uniformity of polishing of complex flow channels.
[0031] (4) The present invention uses a traction rope to adjust the position of the local blockage, and through a three-way connector, pipeline and adjustment valve, a parallel channel with the polishing unit is formed, thereby realizing the position of the blockage and the overall sealing of the device. Attached Figure Description
[0032] Figure 1 This is a front cross-sectional view of the device of the present invention (section lines are not shown).
[0033] Figure 2 This is an enlarged view of the interior of the workpiece of the present invention.
[0034] In the diagram: 1. Piston rod; 2. Piston cylinder; 3. Piston cylinder bracket; 4. Piston; 5. Connector; 6. Blocking ball; 7. Guide ring; 8. Workpiece; 9. Work platform; 10. Adjustment valve; 11. Traction rope. Detailed Implementation
[0035] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.
[0036] like Figure 1-2As shown, a device for controllable fluid polishing of complex internal flow channels includes a working platform 9, a fluid processing unit, and a controllable blocking ball unit; there are two fluid processing units, which are symmetrically installed on the left and right sides of the working platform 9; the complex flow channel, i.e., the left and right ends of the workpiece 8, is connected to the fluid processing units on the left and right sides respectively.
[0037] The fluid processing unit includes a piston 4, a piston cylinder 2, a piston rod 1, a connecting piece 5, and a piston cylinder support 3. The piston cylinder 2 is fixedly connected to the working platform 9 via the piston cylinder support 3. The inner end of the piston rod 1 is fixedly connected to the piston 4, and the piston rod 1 is slidably connected to the opening at the outer end of the piston cylinder 2. The piston 4 is slidably connected to the inner surface of the piston cylinder 2, and polishing liquid is injected into the cavity between the inner side of the piston 4 and the inner surface of the piston cylinder 2. The outlet at the inner end of the piston cylinder 2 is connected to one end of the connecting piece 5, and the other end of the connecting piece 5 communicates with the workpiece 8. A connecting piece 5 is connected to each end of the workpiece 8 to ensure the sealing of the entire device and to clamp the workpiece 8 to determine its position.
[0038] The workpiece 8 is located in the center of the fluid processing unit; one end of the connector 5 is connected to the piston cylinder 2 and kept stationary, while the other end communicates with the workpiece 8. The controllable blocking ball unit is located inside the workpiece 8 and includes a blocking ball 6, a guide ring 7, an adjusting valve 10, and a traction rope 11. By changing the length of the traction rope 11 entering the flow channel inside the workpiece 8, the position of the blocking ball 6 is controlled, thereby controlling the flushing area, forming local blockage, and changing the effective diameter of the polishing fluid flow area. The traction rope 11 is located inside the workpiece 8; the blocking ball 6 is located inside the workpiece 9 and is connected by the traction rope 11; the guide ring 7 is located on both sides of the small ball and is connected by the traction rope 11, with a distance of 2mm from the blocking ball 6; the adjusting valve 10 is connected to the traction rope 11 on both sides, and by adjusting the position of the adjusting valve 10, the length of the traction rope 11 on both sides of the blocking ball 6 is controlled, thereby adjusting the position of the blocking ball 6 inside the workpiece 8.
[0039] According to the apparatus described above, the present invention provides a controllable fluid polishing method for internal channels of complex structures, comprising the following steps:
[0040] Step 1: Install and connect the polishing device in the order of the process and check the airtightness of the device.
[0041] Step 2: The workpiece 8 is made of stainless steel, with an inner diameter of Φ0.3mm, an outer diameter of Φ0.6mm, and an initial surface roughness of 2μm. Alumina is selected as the polishing medium. 200mL of polishing fluid is prepared by mixing alumina and water at a mass ratio of 3:7. The prepared polishing fluid is stirred with a magnetic stirrer for 10 minutes. The well-stirred polishing fluid is then drawn into the inner cavity of piston cylinder 2 in the two fluid processing units.
[0042] Step 3: The workpiece 8 is clamped and fixed between two fluid processing units. Both ends of the workpiece 8 are connected to the inner cavity of the piston cylinder 2 through the connector 5, so that the polishing liquid can enter the interior of the workpiece 8 for processing.
[0043] Step 4: Push and pull the piston rods 1 on the left and right sides in sequence to make the polishing liquid move rapidly in the inner cavity of the left and right piston cylinders 2 and inside the workpiece 8, so that the flow rate of the polishing liquid reaches 35mL / s and is continuously flushed 1000 times. Every fifty flushes, the position of the adjustment valve is moved by 1mm, thereby changing the length of the traction rope 11 entering the inner flow channel and controlling the blocking ball 6 to produce a blocking effect in different areas of the workpiece.
[0044] Step 5: After processing is complete, stop pushing the piston rod 1, remove the stainless steel workpiece 8, put it into an ultrasonic cleaner for cleaning, and use an air gun to dry its inner surface to remove any residual polishing liquid.
[0045] Step 6: Perform a bevel cut on the machined workpiece 8, and inspect the surface quality of the inner surface at the cross-section. The overall roughness Ra is about 0.04 μm, and the local roughness is optimal, reaching Ra 0.03 μm.
[0046] This invention uses specific examples to illustrate the principles and implementation methods of this application. The above examples are only for the purpose of helping to understand the method and core ideas of this application. The above descriptions are only preferred embodiments of this application. It should be noted that due to the limitations of written expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the concept and technical solution of the application to other situations without modification, should all be considered within the scope of protection of this application.
Claims
1. A device for controllable fluid polishing of complex internal flow channels, characterized in that, The device includes a working platform (9), a fluid processing unit, and a controllable blocking ball unit; there are two fluid processing units, which are symmetrically installed on the left and right sides of the working platform (9); the complex flow channel, i.e., the workpiece (8), is located between the two fluid processing units, and the outlet end and inlet end of the workpiece (8) are respectively connected to the fluid processing units on the left and right sides; the controllable blocking ball unit is located inside the workpiece (8), and a connector (5) is connected to each end of the workpiece (8) to ensure the sealing of the entire device and to clamp the workpiece (8) to determine its position; The fluid processing unit includes a piston (4), a piston cylinder (2), a piston rod (1), a connector (5), and a piston cylinder bracket (3); the piston cylinder (2) is fixedly connected to the work platform (9) through the piston cylinder bracket (3), the piston (4) is installed inside the piston cylinder (2), and polishing liquid is poured into the cavity between the inner side of the piston (4) and the inner surface of the piston cylinder (2); the inner end of the piston rod (1) is fixedly connected to the piston (4), and the piston rod (1) is slidably connected to the opening at the outer end of the piston cylinder (2); the outlet at the inner end of the piston cylinder (2) is connected to one end of the workpiece (8) through the connector (5); The controllable blocking ball unit includes a blocking ball (6), two guide rings (7), an adjusting valve (10), and a traction rope (11). The blocking ball (6) is located inside the workpiece (8) and is connected by the traction rope (11). The guide rings (7) are located on both sides of the blocking ball (6) and are connected by the traction rope (11). To prevent the blocking ball (6) from deviating from the central axis of the flow channel when the tension of the traction rope (11) is too large, the guide rings (7) are used to support the traction rope (11). The two guide rings (7) ensure that the center of the blocking ball (6) is located on the central axis of the flow channel of the workpiece (8). The adjusting valve (10) is connected to the traction rope (11) on both sides. By adjusting the position of the adjusting valve (10), the length of the traction rope (11) on both sides of the blocking ball (6) is controlled, thereby adjusting the position of the blocking ball (6) inside the workpiece (8) and controlling the flushing area. The diameter of the blocking ball (6) is smaller than the inner flow channel diameter of the workpiece (8), which is used to form a local blockage and polishing gap. The polishing liquid can only flow through the gap at high speed. By changing the diameter of the polishing liquid flow area, the flow rate and pressure of the polishing liquid are increased, thereby controlling the polishing intensity and realizing controllable polishing of any area on the inner surface of the complex flow channel part.
2. The apparatus for controllable fluid polishing of complex internal flow channels according to claim 1, characterized in that, The distance between the traction rope (11) and the blocking ball (6) is 1-3 mm.
3. The apparatus for controllable fluid polishing of complex internal flow channels according to claim 1, characterized in that, The guide ring (7) is an umbrella rib support ring structure; the maximum outer diameter of the guide ring (7) is the same as the inner diameter of the flow channel of the workpiece (8), and the cross-sectional area of the guide ring (7) is small, so it does not affect the fluid flow state in the flow channel of the workpiece (8).
4. The apparatus for controllable fluid polishing of complex internal flow channels according to claim 1, characterized in that, The polishing medium in the polishing slurry is selected according to the workpiece material: when the workpiece (8) is made of aluminum-silicon alloy, the polishing slurry is made of silicon carbide; when the workpiece (8) is made of stainless steel, the polishing slurry is made of aluminum oxide; when the workpiece (8) is made of cast iron, the polishing slurry is made of diamond powder.
5. A method for controllable fluid polishing of internal channels in complex structures, characterized in that, The method, based on the apparatus described in any one of claims 1-4, performs polishing of the inner surface of the workpiece (8), and includes the following steps: Step 1: Select polishing medium according to the material of workpiece (8) and prepare polishing liquid. Stir the prepared polishing liquid evenly and then suck it into the inner cavity of the piston cylinder (2) of the two fluid processing units. Step 2: Connect the outlet of piston cylinder (2) to connector (5), and connect it to the inlet and outlet ends of workpiece (8) through the internal buckle of connector (5). After the whole connection is completed, check the sealing performance. Step 3: Push the piston rods (1) at both ends of the workpiece (8) to move synchronously by pushing the external push rod, so that while one side piston cylinder (2) pushes out the high pressure polishing liquid, the other side piston cylinder (2) draws in the polishing liquid. Due to the presence of the local blockage of the controllable blocking ball unit in the workpiece (8), the flow rate of the polishing liquid is small before the blockage, the fluid pressure loss is small, and the high pressure is maintained. When the blockage is passed, the pressure is completely released and converted into high speed, which drives the abrasive particles in the polishing liquid to remove material from the inner wall surface of the workpiece (8). The polishing liquid is pushed back and forth by the piston rod (1) to brush the inner surface of the workpiece (8), thereby polishing the inner surface of the workpiece (8). Step 4: Change the length of the traction rope (11) entering the inner flow channel by adjusting the position valve (10) to control the blocking ball (6) to produce a blocking effect in different areas of the workpiece; Step 5: After processing is completed, stop changing the length of the traction rope (11) entering the inner channel, remove the workpiece (8), put it into the ultrasonic cleaner for cleaning, and at the same time use water to rinse the inner channel of the workpiece (8) until there is no polishing liquid residue in the channel. Step 6: Inspect the processed workpiece (8). If the quality of its inner surface reaches the expected target, the polishing process is completed.