A method of magnetorheological finishing

Abstract

The application discloses a magneto-rheological polishing method and relates to the polishing technical field.The method comprises the following steps: constructing a magnetic field generating device with a ring gap structure;filling the magneto-rheological fluid in the ring gap structure, and then fixing a workpiece to be polished so that the workpiece to be polished is immersed in the magneto-rheological fluid; setting magneto-rheological polishing parameters, starting the magnetic field generating device and adjusting the magnetic field strength, forming a ring magnetic field with different magnetic field strengths, and rotating the workpiece to be polished relative to the magneto-rheological fluid to realize polishing of the surface of the workpiece to be polished.The method can improve the polishing precision of complex curved surface structures, and under the action of the ring magnetic field with adjustable magnetic field strength, the magneto-rheological polishing fluid can simultaneously polish the inner and outer surfaces of the workpiece, thereby improving the polishing efficiency; the strong-viscosity magnetic force brush can remove the surface material of the workpiece to be polished, and the method can be suitable for polishing workpieces of various materials and complex curved surfaces and the inner and outer surfaces thereof.

Description

Technical Field

[0001] This application relates to the field of polishing technology, and in particular to a magnetorheological polishing method. Background Technology

[0002] Magnetorheological polishing (MRP) involves adding polishing powder (magnetically sensitive particles) to a magnetorheological fluid. The fluid solidifies under a strong magnetic field, forming a Bingham viscoplastic material (known as the "Bingham effect") with a certain hardness and elasticity, capable of withstanding significant shear stress in the processing area. This material serves as a controllable point-like polishing tool for workpiece polishing. MRP offers advantages such as high surface accuracy, low surface roughness, easy process control, shallow subsurface damage depth, and no new damage during processing, making it widely applicable in precision machining applications requiring high precision. Unlike traditional polishing and grinding, MRP incorporates electromagnetic principles, achieving high precision, especially for aspherical workpieces. However, traditional MRP is less effective for polishing complex curved surfaces, struggling to achieve precise polishing and requiring improved accuracy. Furthermore, changing the magnetic field strength necessitates disassembling the polishing disc and replacing the permanent magnet, resulting in lower processing efficiency and longer polishing times. Summary of the Invention

[0003] The main objective of this application is to provide a magnetorheological polishing method that aims to solve the technical problem that existing magnetorheological polishing methods do not achieve ideal polishing results on complex curved surfaces.

[0004] To achieve the above objectives, this application proposes a magnetorheological polishing method, comprising the following steps:

[0005] Construct a magnetic field generating device with an annular gap structure;

[0006] The annular gap structure is filled with magnetorheological fluid, and then the workpiece to be polished is fixed so that the workpiece to be polished is immersed in the magnetorheological fluid.

[0007] Set the magnetorheological polishing parameters, turn on the magnetic field generator and adjust the magnetic field strength to form a ring magnetic field with different magnetic field strengths, and make the workpiece to be polished rotate relative to the magnetorheological fluid to achieve polishing of the surface of the workpiece to be polished.

[0008] Optionally, the step of constructing a magnetic field generating device with an annular gap structure includes:

[0009] An electromagnet is formed by winding a coil on an iron core and connecting the coil to a direct current.

[0010] A magnetic plate is connected to the outside of the iron core so that the magnetic plate and the electromagnet form a closed circuit;

[0011] Then, an annular groove concentric with the iron core is made on the magnetic conductive plate to form an annular gap structure.

[0012] Optionally, the step of turning on the magnetic field generating device and adjusting the magnetic field strength to form a ring magnetic field with different magnetic field strengths includes:

[0013] Turn on the DC current to energize the coil and induce the iron core, so that the iron core and the magnetic plate form a radial annular magnetic field;

[0014] By adjusting the magnitude of the DC current using a potentiometer, the coil is controlled to induce different magnetic field strengths in the iron core, thus forming a ring-shaped magnetic field with different magnetic field strengths.

[0015] Optionally, the magnetorheological fluid includes deionized water, modified magnetic particles, nano-silica, modified abrasive, antioxidant, wetting agent, and pH adjuster.

[0016] Optionally, the preparation steps of the modified magnetic particles include:

[0017] Nano-iron powder, polyethylene glycol with a molecular weight of 800-900, and anhydrous ethanol are ball-milled together for 2-3 hours, and then dried under vacuum of 0.1MPa-0.2MPa and temperature of 80℃-90℃ for 2.5-3.5 hours to obtain polyethylene glycol-coated nano-iron powder, namely the modified magnetic particles.

[0018] Optionally, the modified abrasive is obtained by grafting superhydrophilic polyvinyl alcohol onto the surface of nanodiamond using an ultraviolet light method.

[0019] Optionally, the preparation step of the magnetorheological fluid includes:

[0020] Antioxidant, wetting agent and modified abrasive are added to deionized water and mixed well to obtain the initial solution;

[0021] The initial solution is stirred, and modified magnetic particles and nano-silica are added in batches, along with deionized water. After the process is completed, ultrasonic dispersion and emulsification are performed, and then a pH adjuster is added to obtain the magnetorheological fluid.

[0022] Optionally, in the step of fixing the workpiece to be polished, the workpiece to be polished is fixed by a clamping device, the clamping device including a robotic arm, a rotating tray and a workpiece shaft, one end of the robotic arm clamps the workpiece to be polished and the other end is connected to the rotating tray, the workpiece shaft passes through the center of the rotating tray and is located directly above the magnetic field generating device.

[0023] Optionally, the step of rotating the workpiece to be polished relative to the magnetorheological fluid includes:

[0024] The rotating pallet is driven to make the workpiece to be polished rotate along the rotating pallet, while the robotic arm drives the workpiece to be polished to perform a reciprocating swing motion.

[0025] Optionally, the step of setting the magnetorheological polishing parameters includes:

[0026] The magnetorheological polishing time was set to 110-130 min, and the magnetic field strength of the annular magnetic field was 1.12 T-1.35 T.

[0027] This application constructs a magnetic field generating device with an annular gap structure to form an annular magnetic field. For polishing complex curved surfaces, since the workpiece is curved, the magnetic field acting on the surface has components perpendicular to the surface and parallel to the surface. The component perpendicular to the surface mainly provides pressure on the workpiece surface and promotes the chemical reaction between the magnetorheological fluid and the workpiece surface, while the component parallel to the surface can control the amount of material removed. However, the magnetic field strength generated by ordinary permanent magnets is inconsistent at different locations. When the workpiece with a complex curved surface rotates relative to the magnetorheological fluid, it is impossible to guarantee the uniformity of the components perpendicular to and parallel to the workpiece surface, making it difficult to achieve precise polishing of the curved surface. Therefore, this application constructs an annular magnetic field structure for magnetorheological polishing, which can still guarantee the consistency of the circumferential magnetic field strength when the workpiece rotates relative to the magnetorheological fluid, thereby making the workpiece... The polishing is more uniform. The high vertical component of the magnetic induction intensity of the annular magnetic field acting on the complex curved surface promotes the contact reaction between the magnetorheological fluid and the complex curved surface. Then, the uniform parallel component of the annular magnetic field acting on the complex curved surface promotes the removal of material from the complex curved surface by the abrasive formed by the magnetorheological fluid. This enables precise polishing of complex curved surface structures and improves polishing accuracy. Compared with traditional single-sided polishing, this application can simultaneously polish the inner and outer surfaces of the workpiece, thereby greatly improving polishing efficiency. Moreover, under the action of the annular magnetic field with adjustable magnetic field strength, the magnetorheological polishing fluid forms a flexible adaptive solid-like substance, which increases the viscosity of the magnetorheological polishing fluid and forms a more efficient flexible "fixed" high-viscosity abrasive. The high-viscosity magnetic brush removes the material from the surface of the polished workpiece, achieving better polishing effect. It is applicable to polishing of various materials, various complex curved workpieces and their inner and outer surfaces. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the magnetorheological polishing principle described in the embodiments of this application;

[0030] Figure 2 This is a schematic diagram of the clamping device described in the embodiments of this application.

[0031] Figure label:

[0032] 1-Iron core; 2-Coil; 3-Magnetic plate; 4-Clamping device; 41-Robotic arm; 42-Rotating tray; 43-Workpiece shaft; 5-Workpiece to be polished.

[0033] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0035] To address the technical problems existing in the prior art, embodiments of this application provide a magnetorheological polishing method, comprising the following steps:

[0036] Construct a magnetic field generating device with an annular gap structure;

[0037] The annular gap structure is filled with magnetorheological fluid, and then the workpiece to be polished is fixed so that the workpiece to be polished is immersed in the magnetorheological fluid.

[0038] Set the magnetorheological polishing parameters, turn on the magnetic field generator and adjust the magnetic field strength to form a ring magnetic field with different magnetic field strengths, and make the workpiece to be polished rotate relative to the magnetorheological fluid to achieve polishing of the surface of the workpiece to be polished.

[0039] This application constructs a magnetic field generating device with an annular gap structure to form an annular magnetic field. For polishing complex curved surfaces, since the workpiece is curved, the magnetic field acting on the surface has components perpendicular to the surface and parallel to the surface. The component perpendicular to the surface mainly provides pressure on the workpiece surface and promotes the chemical reaction between the magnetorheological fluid and the workpiece surface, while the component parallel to the surface can control the amount of material removed. However, the magnetic field strength generated by ordinary permanent magnets is inconsistent at different locations. When the workpiece with a complex curved surface rotates relative to the magnetorheological fluid, it is impossible to guarantee the uniformity of the components perpendicular to and parallel to the workpiece surface, making it difficult to achieve precise polishing of the curved surface. Therefore, this application constructs an annular magnetic field structure for magnetorheological polishing, which can still guarantee the consistency of the circumferential magnetic field strength when the workpiece rotates relative to the magnetorheological fluid, thereby making the workpiece... The polishing is more uniform. The high vertical component of the magnetic induction intensity of the annular magnetic field acting on the complex curved surface promotes the contact reaction between the magnetorheological fluid and the complex curved surface. Then, the uniform parallel component of the annular magnetic field acting on the complex curved surface promotes the removal of material from the complex curved surface by the abrasive formed by the magnetorheological fluid. This enables precise polishing of complex curved surface structures and improves polishing accuracy. Compared with traditional single-sided polishing, this application can simultaneously polish the inner and outer surfaces of the workpiece, thereby greatly improving polishing efficiency. Moreover, under the action of the annular magnetic field with adjustable magnetic field strength, the magnetorheological polishing fluid forms a flexible adaptive solid-like substance, which increases the viscosity of the magnetorheological polishing fluid and forms a more efficient flexible "fixed" high-viscosity abrasive. The high-viscosity magnetic brush removes the material from the surface of the polished workpiece, achieving better polishing effect. It is applicable to polishing of various materials, various complex curved workpieces and their inner and outer surfaces.

[0040] As one possible implementation of this application, the step of constructing a magnetic field generating device with an annular gap structure includes:

[0041] A coil 2 is wound on an iron core 1 and connected to a direct current to form an electromagnet.

[0042] A magnetic conductive plate 3 is connected to the outside of the iron core 1 so that the magnetic conductive plate 3 and the electromagnet form a closed circuit;

[0043] Then, an annular groove concentric with the iron core 1 is formed on the magnetic plate 3 to create an annular gap structure.

[0044] like Figure 1 As shown, the magnetic field generating device of this application includes an iron core 1, a coil 2 and a magnetic plate 3. The coil 2 is wound on the iron core 1 and is connected to a direct current. The magnetic plate 3 is connected to the iron core 1. An annular groove concentric with the iron core 1 is opened on the magnetic plate 3 to form an annular gap structure. When the coil 2 is energized by a direct current, an annular magnetic field can be generated.

[0045] As one possible implementation of this application, the step of turning on the magnetic field generating device and adjusting the magnetic field strength to form a ring magnetic field with different magnetic field strengths includes:

[0046] Turn on the DC current to energize the coil 2 and induce the iron core 1, so that the iron core 1 and the magnetic plate 3 form a radial annular magnetic field;

[0047] By adjusting the magnitude of the DC current using a potentiometer, the coil 2 can be controlled to sense different magnetic field intensities in the iron core 1, thus forming a ring-shaped magnetic field with different intensities.

[0048] This application uses direct current to energize coil 2 and induce iron core 1 to form an electromagnet; the magnetic plate 3 can form a closed circuit with the electromagnet, so that iron core 1 and magnetic plate 3 form a radial ring magnetic field. By directly adjusting the magnitude of the direct current through a potentiometer, the coil 2 can induce iron core 1 to generate different magnetic field intensities, directly forming ring magnetic fields with different magnetic field intensities. When it is necessary to change the magnetic field intensity, it is not necessary to disassemble the polishing disc to replace the permanent magnet. The magnetic field intensity can be changed by adjusting the magnitude of the direct current, thereby improving processing efficiency and shortening polishing time.

[0049] As one possible implementation of this application, the magnetorheological fluid includes deionized water, modified magnetic particles, nano-silica, modified abrasive, antioxidant, wetting agent, and pH adjuster.

[0050] Magnetorheological fluids, acting as polishing "grinding heads," significantly influence the effectiveness of magnetorheological polishing. However, due to the large density differences among the various components in the magnetorheological fluid, its stability is poor, making it prone to particle sedimentation, agglomeration, and rusting, thus affecting polishing performance. Therefore, this application uses a water-based magnetorheological fluid and modifies the magnetic particles and abrasives to reduce particle agglomeration. Simultaneously, nano-silica is added. Because nano-silica has a large specific surface area, it easily forms a stable three-dimensional structure, providing support and buffering for the modified magnetic particles, thereby slowing down sedimentation. Furthermore, nano-silica gelates after entering the magnetorheological fluid, increasing its viscosity and reducing its fluidity to some extent, further mitigating sedimentation.

[0051] Specifically, the wetting agent is a polyol, which can promote the dispersion of magnetic particles and abrasives in the water-based magnetorheological fluid and reduce particle agglomeration. The antioxidant is sodium carbonate, and the pH adjuster is one of ammonia, sodium hydroxide solution, and potassium hydroxide solution. Since the magnetic particles are immersed in the liquid for a long time and are in contact with air, they are easily oxidized and lose their magnetism, reducing the magnetization performance of the magnetorheological fluid. Therefore, adding a pH adjuster to the magnetorheological fluid can maintain an alkaline environment and further slow down the oxidation rate of the magnetic particles through the antioxidant.

[0052] As one possible implementation method of this application, the preparation steps of the modified magnetic particles include:

[0053] Nano-iron powder, polyethylene glycol with a molecular weight of 800-900, and anhydrous ethanol are ball-milled together for 2-3 hours, and then dried under vacuum of 0.1MPa-0.2MPa and temperature of 80℃-90℃ for 2.5-3.5 hours to obtain polyethylene glycol-coated nano-iron powder, namely the modified magnetic particles.

[0054] This application uses nano-iron powder as magnetic particles. Since pure iron powder has a small particle size, the van der Waals attraction between iron powder particles is prone to agglomeration. Therefore, this application coats the nano-iron powder with polyethylene glycol and combines it with nano-silica. The three-dimensional network structure increases the distance between magnetic particles, thereby weakening the van der Waals force, reducing particle agglomeration, significantly improving the sedimentation stability of the magnetorheological fluid, and maintaining the excellent magnetorheological effect of the magnetorheological fluid.

[0055] As one possible implementation of this application, the modified abrasive is obtained by grafting superhydrophilic polyvinyl alcohol onto the surface of nanodiamond using an ultraviolet light method.

[0056] This application grafts superhydrophilic polyvinyl alcohol onto the surface of nanodiamonds, which can give the modified abrasive better hydrophilicity and dispersibility, thereby promoting the dispersion of the abrasive in a water-based polishing fluid environment. In the magnetorheological polishing process, as the polishing fluid flows, water molecules react with the surface-grafted polyvinyl alcohol, thereby weakening the deposition on the workpiece surface caused by the increase in abrasive gravity due to abrasive agglomeration, and enabling the abrasive particles to be carried away by water molecules during polishing without leaving residue on the workpiece surface.

[0057] Specifically, when the abrasive particle size increases, the number of effective polishing abrasive particles in the polishing area decreases. At the same time, when the normal pressure remains unchanged, the load borne by the abrasive particles in the effective polishing area also increases. At this time, under the action of the normal pressure, the abrasive particles penetrate deeper into the workpiece surface. The preferred particle size of the abrasive in this application is 2μm.

[0058] As one possible implementation of this application, the preparation steps of the magnetorheological fluid include:

[0059] Antioxidant, wetting agent and modified abrasive are added to deionized water and mixed well to obtain the initial solution;

[0060] The initial solution is stirred, and modified magnetic particles and nano-silica are added in batches, along with deionized water. After the process is completed, ultrasonic dispersion and emulsification are performed, and then a pH adjuster is added to obtain the magnetorheological fluid.

[0061] In preparing the magnetorheological fluid, antioxidants, wetting agents, and modified abrasives are first added to deionized water to prepare an initial solution. Then, modified magnetic particles and nano-silica are added, which is more conducive to the dispersion of magnetic particles and abrasives. Ultrasonic dispersion and emulsification are then used to further improve the dispersion of magnetic particles and abrasives in the magnetorheological fluid environment. Finally, a pH adjuster is added to the magnetorheological fluid to maintain an alkaline environment and slow down the oxidation rate of magnetic particles.

[0062] In one possible implementation of this application, in the step of fixing the workpiece to be polished, the workpiece to be polished is fixed by a clamping device 4. The clamping device 4 includes a robotic arm 41, a rotating tray 42 and a workpiece shaft 43. One end of the robotic arm 41 clamps the workpiece to be polished 5, and the other end is connected to the rotating tray 42. The workpiece shaft 43 passes through the center of the rotating tray 42 and is located directly above the magnetic field generating device.

[0063] This application uses a clamping device 4 to achieve the rotation of the workpiece 5 to be polished relative to the magnetorheological fluid. First, the rotating tray 42 is driven. Under the rotation of the rotating tray 42, the robotic arm 41 connected to the rotating tray 42 is driven to rotate, so that the workpiece 5 to be polished rotates around the workpiece axis 43. The robotic arm 41 can reciprocate. Simultaneously, the robotic arm 41 is driven to perform reciprocating oscillation motion, which drives the workpiece 5 to reciprocate, so that the workpiece 5 to be polished undergoes a compound motion relative to the magnetorheological fluid. This promotes the complete removal of the material from the workpiece 5 by the "abrasive" formed by the magnetorheological fluid. Especially for complex curved surface structures, the compound motion of the workpiece 5 to be polished can promote full contact between the magnetorheological fluid and the complex curved surface.

[0064] As one possible implementation of this application, the step of rotating the workpiece to be polished relative to the magnetorheological fluid includes:

[0065] The rotating tray 42 is driven to make the workpiece 5 to be polished rotate along the rotating tray 42, while the robotic arm 41 drives the workpiece 5 to be polished to perform a reciprocating swing motion.

[0066] like Figure 2 As shown, Figure 2The motion state of the workpiece at a certain instant is determined by taking the instantaneous point W on the workpiece surface and analyzing its relative velocity with the magnetorheological fluid. The velocity V of point W rotating along the rotating tray 42 is also considered. x It can be represented as:

[0067] V x =ω1+R

[0068] In the formula, ω1 represents the angular velocity of point W as it rotates, and R represents the distance from point W to workpiece axis 43.

[0069] The linear velocity V of point W undergoing reciprocating oscillation motion y It can be represented as:

[0070] V y =ω2×r

[0071] In the formula, ω2 represents the angular velocity of point W as it oscillates back and forth, and r represents the distance from point W to the center of the oscillation.

[0072] The relative velocity V between instantaneous point W and the magnetorheological fluid can then be expressed as:

[0073]

[0074] The workpiece 5 to be polished undergoes a combined motion of rotation and reciprocating oscillation, enabling it, especially workpieces with complex curved surfaces, to fully interact with the magnetorheological polishing fluid. During the polishing process, magnetic particles form radially distributed magnetic chains in the annular magnetic field, creating a highly viscous magnetic brush. When the workpiece undergoes a combined motion in the annular magnetic field, the radially distributed magnetic chains can break, forming multiple micro-brush heads that act on the curved surface. The temporarily broken magnetic chains tend to heal each other under the influence of the magnetic field, which will compress the abrasive particles evenly distributed in these magnetic brush heads, causing the abrasive particles to interact with the workpiece surface to promote material removal.

[0075] As one possible implementation of this application, the step of setting the magnetorheological polishing parameters includes:

[0076] The magnetorheological polishing time was set to 110-130 min, and the magnetic field strength of the annular magnetic field was 1.12 T-1.35 T.

[0077] Within a magnetic field strength range of 1.12T-1.35T, polishing the workpiece for 120 minutes can quickly remove material and obtain a high-precision, high-quality surface.

[0078] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0079] Example 1

[0080] A magnetorheological polishing method includes the following steps:

[0081] An electromagnet is formed by winding a coil on an iron core and connecting the coil to a direct current.

[0082] A magnetic plate is connected to the outside of the iron core so that the magnetic plate and the electromagnet form a closed circuit;

[0083] Then, an annular groove concentric with the iron core is formed on the magnetic conductive plate to create an annular gap structure;

[0084] Nano-iron powder, polyethylene glycol with a molecular weight of 800 and anhydrous ethanol were ball-milled together for 2.5 hours, and then dried for 3 hours under a vacuum of 0.1 MPa and a temperature of 80°C to obtain polyethylene glycol-coated nano-iron powder, i.e. modified magnetic particles.

[0085] Modified abrasives were obtained by grafting superhydrophilic polyvinyl alcohol onto the surface of nanodiamonds using ultraviolet light.

[0086] Sodium carbonate, polyol and modified abrasive were added to deionized water and mixed well to obtain the initial solution.

[0087] The initial solution was stirred, and modified magnetic particles and nano-silica were added in batches, along with deionized water. After the process was completed, ultrasonic dispersion and emulsification were performed, and then ammonia was added to adjust the pH to obtain the magnetorheological fluid.

[0088] The annular gap structure is filled with magnetorheological fluid, and the workpiece to be polished is fixed by a clamping device so that the workpiece to be polished is immersed in the magnetorheological fluid.

[0089] Turn on the DC current to energize the coil and induce the iron core, so that the iron core and the magnetic plate form a radial annular magnetic field;

[0090] The magnitude of the DC current is adjusted by a potentiometer to control the coil to induce different magnetic field intensities in the iron core, forming a ring magnetic field with different magnetic field intensities. The magnetorheological polishing time is set to 120 minutes, and the magnetic field intensity of the ring magnetic field is 1.12T-1.35T. Then, the rotating tray is driven to make the workpiece to be polished rotate along the rotating tray. At the same time, the robotic arm drives the workpiece to be polished to perform a reciprocating oscillating motion, thereby achieving the polishing of the surface of the workpiece to be polished.

[0091] Example 2

[0092] A magnetorheological polishing method includes the following steps:

[0093] An electromagnet is formed by winding a coil on an iron core and connecting the coil to a direct current.

[0094] A magnetic plate is connected to the outside of the iron core so that the magnetic plate and the electromagnet form a closed circuit;

[0095] Then, an annular groove concentric with the iron core is formed on the magnetic conductive plate to create an annular gap structure;

[0096] Nano-iron powder, polyethylene glycol with a molecular weight of 900 and anhydrous ethanol were ball-milled together for 3 hours, and then dried under a vacuum of 0.2 MPa and a temperature of 90°C for 2.5 hours to obtain polyethylene glycol-coated nano-iron powder, i.e. modified magnetic particles.

[0097] Modified abrasives were obtained by grafting superhydrophilic polyvinyl alcohol onto the surface of nanodiamonds using ultraviolet light.

[0098] Sodium carbonate, polyol and modified abrasive were added to deionized water and mixed well to obtain the initial solution.

[0099] The initial solution was stirred, and modified magnetic particles and nano-silica were added in batches, along with deionized water. After the process was completed, ultrasonic dispersion and emulsification were performed, and then sodium hydroxide solution was added to adjust the pH to obtain the magnetorheological fluid.

[0100] The annular gap structure is filled with magnetorheological fluid, and the workpiece to be polished is fixed by a clamping device so that the workpiece to be polished is immersed in the magnetorheological fluid.

[0101] Turn on the DC current to energize the coil and induce the iron core, so that the iron core and the magnetic plate form a radial annular magnetic field;

[0102] The magnitude of the DC current is adjusted by a potentiometer to control the coil to induce different magnetic field intensities in the iron core, forming a ring magnetic field with different magnetic field intensities. The magnetorheological polishing time is set to 110 minutes, and the magnetic field intensity of the ring magnetic field is 1.12T-1.35T. Then, the rotating tray is driven to make the workpiece to be polished rotate along the rotating tray. At the same time, the robotic arm drives the workpiece to be polished to perform a reciprocating oscillating motion, thereby achieving the polishing of the surface of the workpiece to be polished.

[0103] Example 3

[0104] A magnetic field generating device includes an iron core 1, a coil 2 and a magnetic plate 3. The coil 2 is wound on the iron core 1 and is connected to a direct current. The magnetic plate 3 is connected to the iron core 1 and an annular groove concentric with the iron core 1 is formed on the magnetic plate 3 to form an annular gap structure.

[0105] When the magnetic field generating device is turned on, the coil 2 is energized by direct current and induces the iron core 1 to form an electromagnet.

[0106] The magnetic plate 3 and the electromagnet form a closed circuit, so that the iron core 1 and the magnetic plate 3 form a radial ring magnetic field;

[0107] By adjusting the magnitude of the DC current using a potentiometer, the coil 2 induces the iron core 1 to generate different magnetic field strengths, thus forming a ring-shaped magnetic field with different magnetic field strengths.

[0108] Example 4

[0109] A clamping device 4 includes a robotic arm 41, a rotating tray 42, and a workpiece shaft 43. One end of the robotic arm 41 clamps the workpiece 5 to be polished, and the other end is connected to the rotating tray 42. The workpiece shaft 43 passes through the center of the rotating tray 42 and is located directly above the magnetic field generating device.

[0110] The workpiece 5 to be polished is rotated relative to the magnetorheological fluid by the clamping device 4. First, the rotating tray 42 is driven. Under the rotation of the rotating tray 42, the mechanical arm 41 connected to the rotating tray 42 is driven to rotate, so that the workpiece 5 to be polished rotates around the workpiece axis 43. At the same time, the mechanical arm 41 makes a reciprocating swing motion, which drives the workpiece 5 to be polished to make a reciprocating swing motion, so that the workpiece 5 to be polished performs a compound motion relative to the magnetorheological fluid.

[0111] Test case

[0112] 1. Select an aluminum alloy workpiece with a rectangular shape and curved surfaces around its perimeter as the polishing test workpiece, and select 8 points on the test workpiece as the test objects. Among them, test points 1, 2, 3, and 4 are the side areas of the test workpiece, and test points 5, 6, 7, and 8 are the curved surface areas. Before polishing, the workpiece is processed using traditional methods to make the surface roughness value of the workpiece reach 0.2μm. Measure the surface roughness of these 8 points. After polishing, measure the surface roughness of these 8 points again and calculate the average surface roughness. The test results are shown in Table 1 below.

[0113] Table 1

[0114] Measurement points Surface roughness (μm) before machining Surface roughness after machining (μm) 1 0.2 0.02 2 0.2 0.02 3 0.2 0.02 4 0.2 0.02 5 0.2 0.05 6 0.2 0.05 7 0.2 0.035 8 0.2 0.03

[0115] As shown in Table 1, after polishing aluminum alloy workpieces using the magnetorheological polishing method of this application, the surface roughness of the aluminum alloy workpieces can be significantly improved compared to before polishing. Furthermore, it can achieve precise polishing of the arc surfaces of aluminum alloy workpieces, resulting in a significant improvement in processing accuracy.

[0116] 2. A stainless steel workpiece with a spherical shape was selected as the polishing test workpiece, and eight points on the test workpiece were selected as the test objects. Among them, test points 1-8 are all spherical curved surface areas. Before polishing, the workpiece was processed using traditional methods to make the surface roughness value of the workpiece reach 0.2μm. The surface roughness of these eight points was measured. After polishing, the surface roughness of these eight points was measured again, and the average surface roughness was calculated. The test results are shown in Table 2 below.

[0117] Table 2

[0118] Measurement points Surface roughness (μm) before machining Surface roughness after machining (μm) 1 0.2 0.015 2 0.2 0.015 3 0.2 0.015 4 0.2 0.012 5 0.2 0.014 6 0.2 0.012 7 0.2 0.015 8 0.2 0.013

[0119] As shown in Table 2, after polishing stainless steel workpieces with spherical shapes using the magnetorheological polishing method of this application, the surface roughness of the stainless steel workpieces can be significantly improved compared to before polishing, indicating that the polishing method of this application still has a good polishing effect on spherical curved surface structures.

[0120] The above description is merely an optional embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the inventive concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A magnetorheological polishing method, characterized in that, Includes the following steps: Construct a magnetic field generating device with an annular gap structure; The annular gap structure is filled with magnetorheological fluid, and then the workpiece to be polished is fixed so that the workpiece to be polished is immersed in the magnetorheological fluid. Set the magnetorheological polishing parameters, turn on the magnetic field generator and adjust the magnetic field strength to form a ring magnetic field with different magnetic field strengths, and make the workpiece to be polished rotate relative to the magnetorheological fluid to achieve polishing of the surface of the workpiece to be polished; The magnetorheological fluid includes deionized water, modified magnetic particles, nano-silica, modified abrasive, antioxidant, wetting agent and pH adjuster. The preparation steps of the modified magnetic particles include: ball milling nano-iron powder, polyethylene glycol with a molecular weight of 800-900 and anhydrous ethanol together for 2h-3h, and then drying under vacuum of 0.1 MPa-0.2 MPa and temperature of 80℃-90℃ for 2.5h-3.5h to obtain polyethylene glycol-coated nano-iron powder, i.e., the modified magnetic particles; The modified abrasive is obtained by grafting superhydrophilic polyvinyl alcohol onto the surface of nanodiamond using an ultraviolet light method; The preparation steps of the magnetorheological fluid include: adding antioxidants, wetting agents and modified abrasives to deionized water, mixing them to obtain an initial solution; stirring the initial solution, adding modified magnetic particles and nano-silica in batches, and replenishing with deionized water; after completion, performing ultrasonic dispersion and emulsification treatment, and then adding a pH adjuster to obtain the magnetorheological fluid.

2. The magnetorheological polishing method according to claim 1, characterized in that, The steps for constructing a magnetic field generating device with an annular gap structure include: An electromagnet is formed by winding a coil on an iron core and connecting the coil to a direct current. A magnetic plate is connected to the outside of the iron core so that the magnetic plate and the electromagnet form a closed circuit; Then, an annular groove concentric with the iron core is made on the magnetic conductive plate to form an annular gap structure.

3. The magnetorheological polishing method according to claim 2, characterized in that, The step of activating the magnetic field generating device and adjusting the magnetic field strength to form a ring magnetic field with different magnetic field strengths includes: Turn on the DC current to energize the coil and induce the iron core, so that the iron core and the magnetic plate form a radial annular magnetic field; By adjusting the magnitude of the DC current using a potentiometer, the coil is controlled to induce different magnetic field strengths in the iron core, thus forming a ring-shaped magnetic field with different magnetic field strengths.

4. The magnetorheological polishing method according to claim 1, characterized in that, In the step of fixing the workpiece to be polished, the workpiece to be polished is fixed by a clamping device, which includes a robotic arm, a rotating tray and a workpiece shaft. One end of the robotic arm clamps the workpiece to be polished and the other end is connected to the rotating tray. The workpiece shaft passes through the center of the rotating tray and is located directly above the magnetic field generating device.

5. The magnetorheological polishing method according to claim 4, characterized in that, The step of rotating the workpiece to be polished relative to the magnetorheological fluid includes: The rotating pallet is driven to make the workpiece to be polished rotate along the rotating pallet, while the robotic arm drives the workpiece to be polished to perform a reciprocating swing motion.

6. The magnetorheological polishing method according to claim 1, characterized in that, The step of setting the magnetorheological polishing parameters includes: setting the magnetorheological polishing time to 110 min-130 min, and the magnetic field strength of the annular magnetic field to 1.12 T-1.35 T.

Images