A flexible polishing tool, a polishing method and a manufacturing method of a polishing magnetic capsule

Abstract

The present application discloses a flexible polishing tool, a polishing method and a manufacturing method of a polishing magnetic capsule. The flexible polishing tool comprises an electromagnet and the polishing magnetic capsule. The polishing magnetic capsule is a magnetic capsule with uneven wall thickness and constant internal pressure, which is made of magnetorheological elastomer. The polishing method is to polish a workpiece to be polished by using the flexible polishing tool, and to change the magnetic field intensity and the polishing angle during the polishing process. The polishing method can make the polishing equipment reduce the intermediate frequency error generated by polishing under the condition of controlling the flexible polishing tool to run a conventional simple path, so the polishing equipment does not need to run a random path, and is not easy to shake or damage. The manufacturing method of the polishing magnetic capsule can manufacture the flexible polishing tool matched with various polishing equipment with different performances according to the parameters of the polishing equipment, so that the polishing equipment with different performances can polish the workpiece to be polished within the respective ability range by using the polishing method.

Description

Technical Field

[0001] This invention relates to the field of workpiece polishing technology, specifically to a flexible polishing tool, a polishing method, and a method for manufacturing a polishing magnetic capsule. Background Technology

[0002] In existing polishing technologies, flexible polishing tools are commonly used for precision polishing due to their high polishing efficiency and ability to conform to the surface of the workpiece. During polishing, flexible polishing tools typically employ conventional, simple paths, such as grating paths. However, because the polishing spots are of uniform size, mid-frequency errors are unavoidable. To address this, existing technologies control the flexible polishing tool to follow random paths, inducing sharp turns and stops to disperse and evenly distribute the surface ripples generated after polishing, thereby reducing mid-frequency errors. However, operating random paths places stringent demands on the performance of the polishing equipment and can easily cause vibrations or even damage to the equipment. Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned defects or problems in the prior art and to provide a flexible polishing tool, a polishing method, and a method for manufacturing a polishing magnetic capsule thereof. Using this flexible polishing tool and the polishing method to polish the workpiece allows the polishing equipment to reduce mid-frequency errors during polishing while controlling the flexible polishing tool to follow a conventional, simple path. Therefore, the polishing equipment does not need to run a random path, making it less prone to vibration or damage. Furthermore, the method for manufacturing this polishing magnetic capsule allows for the production of flexible polishing tools that match the parameters of various polishing equipment with different performance characteristics, enabling polishing equipment with different performance levels to polish the workpiece using the aforementioned polishing method within their respective capabilities.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] The first technical solution relates to a flexible polishing tool, comprising: a base adapted to be fixed to the processing spindle of a polishing device; a polishing magnetic capsule fixed to the base; the polishing magnetic capsule is made of a magnetorheological elastomer, having a shell of uneven thickness and an inner cavity formed by the shell, the inner cavity being filled with gas or non-magnetic powder of micro-nano diameter, thereby supporting the shell and maintaining a constant pressure within the inner cavity for polishing; an electromagnet fixed to the base, adapted to be connected to an external CNC device to generate a linearly adjustable uniform magnetic field within the volume range of the shell; the outer surface of the shell is a spherical surface with a notch, the corresponding inner surface of the sphere is a corrugated surface, and the magnetic field direction of the uniform magnetic field is perpendicular to the plane where the notch is located. The second technical solution is based on the first technical solution, further comprising a polishing pad attached to the outer surface of the shell.

[0006] The third technical solution is based on the first technical solution, wherein the magnetorheological elastomer is made of silicone mixed with magnetic powder, wherein the ratio of silicone to magnetic powder is 6:4.

[0007] The fourth technical solution relates to a polishing method based on the flexible polishing tool described in any one of technical solutions 1-3, comprising the following steps: S1: installing the flexible polishing tool on the processing spindle of the polishing equipment; S2: the processing spindle of the polishing equipment drives the polishing magnetic bag to rotate at high speed, polishing the workpiece to be polished according to the set polishing angle and a simple path composed of straight paths. During the polishing process, the elastic modulus of the polishing magnetic bag is controlled by adjusting the magnetic field strength, thereby adjusting the pressure in the contact area between the polishing magnetic bag and the workpiece to be polished.

[0008] The fifth technical solution is based on the fourth technical solution, wherein, in the simplified path, the polishing angles are different for adjacent straight paths.

[0009] The sixth technical solution relates to a method for manufacturing a polishing magnetic capsule for a flexible polishing tool as described in any of the first to third technical solutions, comprising the following steps: after determining the processing area of ​​the workpiece to be polished, installing an airbag polishing tool with uniform wall thickness and constant air pressure onto the processing spindle of a polishing equipment; the processing spindle of the polishing equipment drives the airbag polishing tool to polish the workpiece to be polished according to a set polishing angle and a simplified path composed of straight paths, obtaining the current pressure distribution curve between the airbag polishing tool and the workpiece to be polished under each straight path; and designing the polishing magnetic capsule shell under each straight path according to the performance of the polishing equipment. The target pressure distribution curve between the workpiece and the workpiece to be polished is calculated, and the temporary wall thickness function of the polishing magnetic capsule shell is obtained. Based on the temporary wall thickness function, the temporary inner cavity filling pressure and the volume magnetic susceptibility of the polishing magnetic capsule are set, and finite element simulation is performed. The temporary wall thickness function and the temporary inner cavity filling pressure are finely adjusted to make the simulation results conform to the target pressure distribution curve, and the final wall thickness function and the final inner cavity filling pressure are obtained. The volume magnetic susceptibility of the polishing magnetic capsule is the volume magnetic susceptibility of the magnetorheological elastomer. Based on the final wall thickness function and the final inner cavity filling pressure, the polishing magnetic capsule is manufactured using a magnetorheological elastomer.

[0010] The seventh technical solution is based on the sixth technical solution, wherein, in the simplified path, the polishing angle and the designed target pressure distribution curve are different under adjacent straight paths.

[0011] The eighth technical solution is based on the sixth technical solution, wherein the calculation of the temporary wall thickness function of the polished magnetic shell includes the following steps:

[0012] The radius of the polished magnetic capsule shell is set to have its center located at... Then we have the equation of the circle:

[0013]

[0014] According to the principle of force balance, we have:

[0015]

[0016] in, This represents the polishing angle corresponding to any straight path. This is the current pressure distribution curve along this straight path. This is the target pressure distribution curve along the straight path. The curve of the magnetic force experienced by the polishing magnetic capsule shell under a set magnetic field along the straight path;

[0017] According to the volume formula for magnetic powder particles, we have:

[0018]

[0019] in, Let be the radius of the magnetic powder particles in the polishing magnetic capsule. The volume of the magnetic powder particles in the polishing magnetic capsule;

[0020] Based on the forces acting in a magnetic field, we have:

[0021]

[0022]

[0023] in, This refers to the magnetic force experienced by a single magnetic powder particle within a polishing magnetic capsule under a set magnetic field strength. The permeability of vacuum. The volume magnetic susceptibility of the magnetic powder particles is denoted as . Indicates the direction of the magnetic field. For the set magnetic field strength, H is the magnetic field gradient;

[0024] Assuming the magnetic powder particles are closely packed within the polished magnetic capsule, then they are arranged in a body-centered cubic pattern, and thus:

[0025]

[0026] in, For polishing the magnetic capsule shell along The thickness along the axial direction, 0.68 is the packing density of the body-centered cubic unit cell, and 1 represents the unit length. Combining the above equations, we can obtain:

[0027]

[0028] in:

[0029]

[0030]

[0031] According to the aforementioned equation of the circle, we can obtain:

[0032]

[0033] The coordinates of any point on the inner surface of the polished magnetic capsule shell can then be expressed as:

[0034]

[0035] According to the Pythagorean theorem, the distance from this point to the center of the circle is:

[0036]

[0037] Then the temporary wall thickness function of the polished magnetic capsule shell can be obtained. :

[0038]

[0039]

[0040] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The flexible polishing tool provided by this invention has a non-uniform wall thickness of the polishing magnetic capsule used for polishing. Therefore, the pressure distribution in the contact area between the magnetic capsule and the workpiece is no longer a Gaussian type, but a shape related to the wall thickness design. Different pressure distributions can be obtained by adjusting the polishing angle between the magnetic capsule and the workpiece. Thus, with a constant rotation speed of the magnetic capsule, polishing spots of different shapes can be obtained. Therefore, even when following a simple path, it can still disperse and evenly distribute the surface ripples generated after polishing, thereby reducing the intermediate frequency error. Compared with using a random path to reduce intermediate frequency error, this invention has lower performance requirements for the polishing equipment and causes less damage to components. Furthermore, since the magnetic capsule is made of magnetorheological elastomer, the stiffness of the magnetic capsule can be controlled by a magnetic field, thereby adjusting the contact pressure between the magnetic capsule and the workpiece. This not only allows for obtaining more polishing spots of varying depths, further dispersing and evenly distributing the surface ripples generated after polishing to reduce intermediate frequency error, but also overcomes the curvature effect.

[0042] 2. Since the outer surface of the shell is a spherical surface with notches and the inner surface is a corrugated surface, the thickness of the shell varies irregularly in a corrugated shape. Therefore, by changing the polishing angle, pressure curves with different shapes and different maximum pressure values ​​can be obtained to meet the needs of actual polishing.

[0043] 3. Since both the outer and inner surfaces of the shell are spherical surfaces with notches and the centers of the spheres do not coincide and the notches are located on the same plane, the polishing pressure contact surface can be uniformly varied by changing the polishing angle, resulting in pressure curves with roughly the same shape but different maximum pressure values, thus meeting the needs of actual polishing.

[0044] 4. A polishing pad can be attached to the outer surface of the housing to form a polishing working surface.

[0045] 5. By making the polishing angles of adjacent straight paths in the simplified path different, the shapes and depths of adjacent polishing spots are different, thus disrupting the surface ripples after polishing and reducing the mid-frequency error.

[0046] 6. Based on the performance of the polishing equipment, namely the range of polishing angles that can be adjusted by different polishing equipment in actual applications, the minimum amount of adjustment of the polishing angle, and the range of adjustable magnetic field strength, the wall thickness of the polishing magnetic bladder is designed and finite element simulation is performed to obtain the final wall thickness function and the final inner cavity filling pressure. The polishing magnetic bladder is then manufactured accordingly, so that the polishing method of the present invention can be applied to different polishing equipment.

[0047] 7. The temporary wall thickness function of the polished magnetic bladder is obtained in advance by formula and then finite element simulation is performed to facilitate fine-tuning to obtain the final wall thickness function and the final inner cavity filling pressure. Attached Figure Description

[0048] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments are briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A perspective view of a flexible polishing tool including a polishing magnetic capsule.

[0050] Figure 2 An exploded view of a flexible polishing tool including a polishing magnetic capsule.

[0051] Figure 3 This is one of the structural schematic diagrams of a polishing magnetic capsule.

[0052] Figure 4 This is the second schematic diagram of the polishing magnetic capsule.

[0053] Figure 5 This is a schematic diagram of the pressure distribution during conventional airbag polishing.

[0054] Figure 6 This is a schematic diagram of the polishing marks on a conventional airbag following the grating path.

[0055] Figure 7 This is a schematic diagram of the residual ripples after polishing the grating path of a conventional airbag.

[0056] Figure 8 This is a schematic diagram of the pressure distribution during the polishing of the polishing magnetic capsule.

[0057] Figure 9 This is a schematic diagram of the force analysis of a polishing magnetic capsule in a uniform magnetic field.

[0058] Explanation of key figure labels:

[0059] 1. Polishing pad, 2. Countersunk bolt, 3. Flange, 4. Polishing magnetic bladder, 5. Rubber sealing ring, 6. Gasket, 7. Electromagnet, 8. Base, 9. Housing, 10. Annular flange, 11. Through hole. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are preferred embodiments of the present invention and should not be considered as excluding other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0061] Unless otherwise expressly defined, the use of terms such as "first," "second," or "third" in the claims, description, and accompanying drawings of this invention is for distinguishing different objects and not for describing a specific order.

[0062] Unless otherwise expressly defined, in the claims, description, and accompanying drawings of this invention, the use of directional terms such as "center," "lateral," "longitudinal," "horizontal," "vertical," "top," "bottom," "inner," "outer," "upper," "lower," "front," "rear," "left," "right," "clockwise," and "counterclockwise" to indicate orientation or positional relationships is based on the orientation and positional relationships shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the specific scope of protection of this invention.

[0063] Unless otherwise expressly defined, the terms "fixed connection" or "fixed connection" used in the claims, description and drawings of this invention should be interpreted broadly to refer to any connection in which there is no displacement or relative rotation relationship between the two parties, including non-removable fixed connection, detachable fixed connection, integral connection and fixed connection by other means or components.

[0064] In the claims, description and accompanying drawings of this invention, the terms "comprising," "having," and variations thereof are used to mean "including but not limited to."

[0065] In the claims, description, and accompanying drawings of this invention, the term "spherical surface with a notch" refers to an incomplete sphere. For example, a spherical cap, or a hemisphere, etc. The term "plane where the notch is located" refers, depending on the context, to the bottom surface of a spherical cap, a hemisphere, or other spherical surfaces with a notch.

[0066] See Figure 1 and Figure 2 This embodiment provides a flexible polishing tool, which includes a base 8, an electromagnet 7, a gasket 6, a rubber sealing ring 5, a polishing magnetic bladder 4, a countersunk bolt 2, a flange 3, and a polishing pad 1.

[0067] The base 8 is adapted to be fixed to the machining spindle of the polishing equipment. It has a cavity (not shown in the figure) and a channel (not shown in the figure) communicating with the cavity.

[0068] The polishing magnetic capsule 4 is made of magnetorheological elastomer. The polishing magnetic capsule 4 has a shell 9 of uneven thickness and an inner cavity formed by the shell 9. The inner cavity is filled with gas or micro / nano-diameter non-magnetic powder, thereby supporting the shell 9 and maintaining a constant pressure within the inner cavity for polishing. Filling can be achieved by fixing the polishing magnetic capsule 4 to the base 8 and then filling it through an extremely fine needle. Complete filling maintains a constant internal pressure within the polishing magnetic capsule 4, allowing it to be supported and ready for polishing. The diameter of the micro / nano-diameter non-magnetic powder is generally less than 50 micrometers. Specifically, the outer surface of the shell 9 of the polishing magnetic capsule 4 is a notched spherical surface; in this embodiment, the outer surface of the shell 9 of the polishing magnetic capsule 4 is a hemispherical surface. Figure 3 and Figure 4 As shown, the housing 9 also has an annular flange 10 at the bottom surface of the hemispherical surface, and the annular flange 10 has through holes 11 matching the number of countersunk bolts 2. The non-uniform thickness of the housing 9 can be as follows: Figure 3 As shown, the inner surface corresponding to the hemispherical surface is corrugated, so that the thickness of the shell 9 has an irregular corrugated shape. Alternatively, as shown... Figure 4As shown, the inner surface corresponding to the hemisphere is a sphere with a notch, and the center of the sphere does not coincide with the outer surface. The notch of the hemisphere and the notch of the inner surface are located on the same plane to make the thickness of the shell 9 vary uniformly. Since the performance of polishing equipment varies in practical applications—for example, the adjustable range of the polishing angle, the minimum change value of the polishing angle adjustment, and the adjustable magnetic field strength range differ—a corresponding polishing magnetic bag 4 can be designed according to the performance of the polishing equipment. The design process includes the following steps:

[0069] Step 1: After determining the processing area of ​​the workpiece to be polished, install an airbag polishing tool with uniform wall thickness and constant air pressure onto the processing spindle of the polishing equipment. The processing spindle of the polishing equipment drives the airbag polishing tool to polish the workpiece according to the set polishing angle and a simplified path composed of straight lines, obtaining the current pressure distribution curve between the airbag polishing tool and the workpiece under each straight path. .like Figures 5-7 As shown, the pressure distribution curve of a conventional airbag polishing tool is typically Gaussian-like. Therefore, when polishing the workpiece along a simple path consisting of straight lines, the polishing spot size is uniform, resulting in residual ripples that cause mid-frequency errors. It is important to note that the polishing angle should be selected based on the performance of the polishing equipment used. Specifically, the polishing angle used each time a straight path is followed should be within the adjustment range of the polishing spindle, and the degree of angle change should be adapted to the minimum change in polishing angle allowed by the equipment.

[0070] Step 2: Based on the performance of the polishing equipment, design the target pressure distribution curve between the shell 9 of the polishing magnetic bag 4 and the workpiece to be polished under various straight paths. The temporary wall thickness function of the shell 9 of the polished magnetic bladder 4 was obtained through calculation. Under adjacent straight paths, the polishing angle and the designed target pressure distribution curve differ. The calculation process is as follows. It should be noted that the magnetic field strength used in the following calculations... For a fixed value, the median value of the magnetic field strength adjustment range of the actual polishing equipment is taken, and the direction of the uniform magnetic field is parallel to the rotation axis of the polishing spindle in step 1; polishing angle It is also a constant value, that is, the polishing angle corresponding to each straight path traveled by the conventional airbag polishing tool in step 1.

[0071] like Figure 8 and Figure 9As shown, the downward pressure of the polishing ball head during actual polishing is very small. For example, with a ball head radius of 320mm, the downward pressure is less than 2mm. In actual engineering, the downward pressure is generally only about 0.8mm. Therefore, the deformation caused by this downward pressure can be ignored in the derivation of the theoretical formula. When this deformation is ignored, the contact surface between the workpiece and the ball head can be regarded as a straight line, and the derivation can be performed on a two-dimensional plane.

[0072] The radius of the shell 9 of the polished magnetic capsule 4 is set to have its center located at... Then we have the equation of the circle:

[0073]

[0074] According to the principle of force balance, we have:

[0075]

[0076] in, This represents the polishing angle corresponding to any straight path. This is the current pressure distribution curve along this straight path. This is the target pressure distribution curve along the straight path. The curve of the magnetic force experienced by the shell 9 of the polishing magnetic capsule 4 under the set magnetic field along the straight path;

[0077] According to the volume formula for magnetic powder particles, we have:

[0078]

[0079] in, The radius of the magnetic powder particles in the polishing magnetic capsule 4 can be obtained directly. The volume of the magnetic powder particles in the polishing magnetic capsule 4;

[0080] Based on the forces acting in a magnetic field, we have:

[0081]

[0082]

[0083] in, This refers to the magnetic force experienced by a single magnetic powder particle in the polishing magnetic capsule 4 under a set magnetic field strength. The permeability of vacuum. The volume magnetic susceptibility of the magnetic powder particles is denoted as . Indicates the direction of the magnetic field. For the set magnetic field strength, H is the magnetic field gradient;

[0084] Assuming the magnetic powder particles are closely packed in the polished magnetic capsule 4, then they are arranged in a body-centered cubic pattern, and thus:

[0085]

[0086] in, The shell 9 of the polished magnetic capsule 4 is along The thickness along the axial direction, 0.68 is the packing density of the body-centered cubic unit cell, and 1 represents the unit length. Combining the above equations, we can obtain:

[0087]

[0088] in:

[0089]

[0090]

[0091] Since the shell 9 of the polishing magnetic capsule 4 is a hemisphere rather than a complete sphere, according to the aforementioned circle equation, we can obtain:

[0092]

[0093] The coordinates of any point on the inner surface of the shell 9 of the polishing magnetic capsule 4 can be expressed as:

[0094]

[0095] According to the Pythagorean theorem, the distance from this point to the center of the circle is:

[0096]

[0097] Then the temporary wall thickness function of the shell 9 of the polished magnetic capsule 4 can be obtained. :

[0098]

[0099]

[0100] Step 3: Based on the temporary wall thickness function, after setting the temporary inner cavity filling pressure and the volumetric magnetic susceptibility of the polishing magnetic bladder 4, finite element simulation is performed. The temporary wall thickness function and temporary inner cavity filling pressure are finely adjusted to make the simulation results conform to the target pressure distribution curve, thus obtaining the final wall thickness function and final inner cavity filling pressure. The volumetric magnetic susceptibility of the polishing magnetic bladder 4 is the volumetric magnetic susceptibility of the magnetorheological elastomer. In this embodiment, the magnetorheological elastomer is made by mixing silicone and magnetic powder in a 6:4 ratio. Therefore, a small portion of the magnetorheological elastomer can be manufactured first, its volumetric magnetic susceptibility measured, and then input into the finite element simulation software for simulation. The temporary inner cavity filling pressure is generally set to be sufficient to support the shell 9, i.e., standard atmospheric pressure.

[0101] Step 4: Based on the final wall thickness function and the final internal cavity filling pressure, a polishing magnetic capsule 4 is manufactured using a magnetorheological elastomer. It is important to note that since the simplified path during actual polishing consists of multiple straight paths, there are multiple polishing angles. Therefore, each time the polishing angle is changed, the above steps need to be repeated to obtain multiple final wall thickness functions, which are then used to manufacture the polishing magnetic capsule 4. The polishing magnetic capsule 4 can be manufactured using 3D printing. After obtaining the multiple final wall thickness functions, a suitable mold is obtained through 3D modeling, and silicone and magnetic powder are injection molded in a 6:4 ratio. Alternatively, magnetic materials can be directly 3D printed. Then, the polishing magnetic capsule 4 is filled according to the final internal cavity filling pressure obtained from finite element simulation.

[0102] An electromagnet 7, fixed to a base 8, is adapted to be connected to an external CNC device to generate a linearly adjustable uniform magnetic field within the volume of the shell 9 of the polishing magnetic capsule 4. Specifically, the electromagnet 7 is housed within a cavity of the base 8, and a gasket 6 is used to encapsulate the electromagnet 7 within the cavity. A wire connected to the electromagnet 7 passes through a channel in the base 8 to connect to the external CNC device. In this embodiment, by placing the electromagnet 7 between the base 8 and the polishing magnetic capsule 4, and ensuring that both the electromagnet 7 and the polishing magnetic capsule 4 are close to the gasket 6, the magnetic field lines are most densely packed near the magnetic poles and have the smallest directional deflection. Therefore, it is possible to cooperate with the external CNC device to test and select a suitable current range, so that within the current range, the magnetic field within the volume of the shell 9 of the polishing magnetic capsule 4 is a uniform magnetic field. Furthermore, without changing the direction of the magnetic field, the magnetic field strength can change uniformly and linearly with the adjustment of the current. The direction of the uniform magnetic field is perpendicular to the plane containing the notch on the outer surface of the shell 9 of the polishing magnetic capsule 4, i.e., perpendicular to the bottom surface of the hemisphere. External CNC equipment is usually integrated into the polishing equipment to facilitate connection of the electromagnet 7.

[0103] The countersunk bolt 2 passes through the flange 3, the through hole 11 on the annular flange 10, and the gasket 6, and is then fixed to the base 8. This secures the polishing magnetic capsule 4 to the base 8. The housing 9 is fixed to the base 8 through its bottom surface, and its hemispherical surface is used to attach the polishing pad 1 for polishing. Furthermore, to seal the gas or micro / nano-sized non-magnetic powder inside the polishing magnetic capsule, a rubber sealing ring 5 is placed between the polishing magnetic capsule 4 and the gasket 6, thus achieving a sealing effect. The gasket 6 has a recessed semicircle with a suitable design radius to stabilize the position of the sealing ring.

[0104] Polishing pad 1 is attached to the outer surface of housing 9 and can be used to contact the workpiece to be polished. There are no special requirements for the selection of polishing pad 1; a conventional polishing pad 1 can be used.

[0105] This embodiment also provides a polishing method. The flexible polishing tool in this embodiment is mounted on the machining spindle of the polishing equipment and connected to an external CNC device. The machining spindle of the polishing equipment drives the polishing magnetic capsule 4 to rotate at high speed. The axis of rotation should be parallel to the direction of the uniform magnetic field generated by the electromagnet 7. Then, the workpiece to be polished is polished according to the set polishing angle and a simple path composed of straight paths. During the polishing process, that is, during each movement along the straight path, the elastic modulus of the polishing magnetic capsule 4 is controlled by adjusting the magnetic field strength, thereby adjusting the pressure between the polishing magnetic capsule 4 and the workpiece to be polished. After completing a straight path, the polishing angle is changed so that the polishing angles under adjacent straight paths are different. Then, the magnetic field strength is repeatedly adjusted so that the shape and size of the polishing spots under adjacent paths are different. The adjustment of the magnetic field strength and the change of the polishing angle should be the same as those in the aforementioned finite element simulation.

[0106] In this embodiment, the flexible polishing tool provided by the present invention has a non-uniform wall thickness of the polishing magnetic capsule 4 used for polishing. Therefore, the pressure distribution in the contact area between the magnetic capsule 4 and the workpiece to be polished is no longer a Gaussian type, but a shape related to the wall thickness design. Different pressure distributions can be obtained by adjusting the polishing angle between the magnetic capsule 4 and the workpiece. Therefore, with a constant rotation speed of the magnetic capsule 4, polishing spots of different shapes can be obtained. Thus, even when following a simple path, it can still disperse and evenly distribute the surface ripples generated after polishing, thereby reducing the intermediate frequency error. Compared with the method of reducing intermediate frequency error using a random path, the present invention has lower performance requirements for the polishing equipment and causes less damage to components. Furthermore, since the magnetic capsule 4 is made of magnetorheological elastomer, the stiffness of the magnetic capsule 4 can be controlled by a magnetic field, thereby adjusting the magnitude of the contact pressure between the magnetic capsule 4 and the workpiece. This not only allows for obtaining more polishing spots of varying depths, further dispersing and evenly distributing the surface ripples generated after polishing to reduce intermediate frequency error, but also overcomes the curvature effect.

[0107] In this embodiment, since the outer surface of the housing 9 is a spherical surface with a notch and the inner surface corresponding to the spherical part is a corrugated surface, the thickness of the housing 9 is irregularly varied in a corrugated shape. Therefore, by changing the polishing angle, pressure curves with different shapes and different maximum pressure values ​​can be obtained to meet the needs of actual polishing.

[0108] In this embodiment, since both the outer and inner surfaces of the shell are spherical surfaces with notches and the centers of the spheres do not coincide and the notches are located on the same plane, the polishing pressure contact surface can be uniformly changed by changing the polishing angle, resulting in pressure curves with roughly the same shape but different maximum pressure values, thus meeting the needs of actual polishing.

[0109] In this embodiment, a polishing pad 1 is attached to the outer surface of the housing 9 to form a polishing working surface.

[0110] In this embodiment, by making the polishing angles of adjacent straight paths in the simplified path different, the shapes and depths of adjacent polishing spots are different, thus disrupting the surface ripples after polishing and reducing the mid-frequency error.

[0111] In this embodiment, based on the performance of the polishing equipment, namely the range of polishing angles that can be adjusted by different polishing equipment in actual applications, the minimum amount of adjustment of the polishing angle, and the range of adjustable magnetic field strength, the wall thickness of the polishing magnetic bladder 4 is designed and finite element simulation is performed to obtain the final wall thickness function and the final inner cavity filling pressure, and then the polishing magnetic bladder 4 is manufactured accordingly, so that the polishing method of the present invention can be applied to different polishing equipment.

[0112] In this embodiment, the temporary wall thickness function of the polished magnetic bladder 4 is obtained in advance by formula and then finite element simulation is performed to facilitate fine-tuning to obtain the final wall thickness function and the final inner cavity filling pressure.

[0113] The foregoing description of the specifications and embodiments is intended to explain the scope of protection of this invention, but does not constitute a limitation on the scope of protection of this invention. Modifications, equivalent substitutions, or other improvements to the embodiments of this invention or a portion thereof that can be obtained by those skilled in the art through logical analysis, reasoning, or limited experimentation, based on the teachings of this invention or the foregoing embodiments, in conjunction with common knowledge, general technical knowledge, and / or existing technology, should all be included within the scope of protection of this invention.

Claims

1. A flexible polishing tool, characterized in that, include: The base (8) is suitable for being fixed to the machining spindle of the polishing equipment; Polishing magnetic capsule (4) is fixed to the base (8); the polishing magnetic capsule (4) is made of magnetorheological elastomer and has a shell (9) of uneven thickness and an inner cavity formed by the shell (9). The inner cavity is filled with gas or non-magnetic powder of micro- and nano-diameter, thereby supporting the shell (9) and keeping the pressure in the inner cavity constant for polishing. An electromagnet (7) is fixed to the base (8) and is adapted to be connected to an external CNC device to generate a linearly adjustable uniform magnetic field within the volume of the housing (9). The outer surface of the shell (9) is a spherical surface with a notch, and the inner surface corresponding to the spherical surface is a corrugated surface. The magnetic field direction of the uniform magnetic field is perpendicular to the plane where the notch is located.

2. The flexible polishing tool as described in claim 1, characterized in that, It also includes a polishing pad (1), which is attached to the outer surface of the housing (9).

3. The flexible polishing tool as described in claim 1, characterized in that, The magnetorheological elastomer is made of silica gel mixed with magnetic powder, wherein the ratio of silica gel to magnetic powder is 6:

4.

4. A polishing method based on the flexible polishing tool according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Install the flexible polishing tool on the processing spindle of the polishing equipment; S2: The processing spindle of the polishing equipment drives the polishing magnetic bag (4) to rotate at high speed. The workpiece to be polished is polished according to the set polishing angle and the simple path composed of straight paths. During the polishing process, the elastic modulus of the polishing magnetic bag (4) is controlled by adjusting the magnetic field strength, and then the pressure of the contact area between the polishing magnetic bag (4) and the workpiece to be polished is adjusted.

5. The polishing method as described in claim 4, characterized in that, In the simplified path, the polishing angles are different for adjacent straight paths.

6. A method for manufacturing a polishing magnetic capsule for a flexible polishing tool as described in any one of claims 1-3, characterized in that, Includes the following steps: After determining the processing area of ​​the workpiece to be polished, an airbag polishing tool with uniform wall thickness and constant air pressure is installed on the processing spindle of the polishing equipment. The processing spindle of the polishing equipment drives the airbag polishing tool to polish the workpiece to be polished according to the set polishing angle and a simple path composed of straight paths, and obtains the current pressure distribution curve between the airbag polishing tool and the workpiece to be polished under each straight path. Based on the performance of the polishing equipment, the target pressure distribution curve between the shell (9) of the polishing magnetic bag (4) and the workpiece to be polished is designed under each straight path, and the temporary wall thickness function of the shell (9) of the polishing magnetic bag (4) is obtained by calculation. Based on the temporary wall thickness function, after setting the temporary inner cavity filling pressure and the volume magnetic susceptibility of the polishing magnetic bladder (4), finite element simulation is performed. The temporary wall thickness function and the temporary inner cavity filling pressure are finely adjusted so that the simulation results conform to the target pressure distribution curve, and the final wall thickness function and the final inner cavity filling pressure are obtained. The volume magnetic susceptibility of the polishing magnetic bladder (4) is the volume magnetic susceptibility of the magnetorheological elastomer. Based on the final wall thickness function and the final cavity filling pressure, a polished magnetic bladder is manufactured using a magnetorheological elastomer (4).

7. The method as described in claim 6, characterized in that, In the simplified path, the polishing angle and the designed target pressure distribution curve are different under adjacent straight paths.

8. The method as described in claim 6, characterized in that, The temporary wall thickness function of the shell (9) of the polished magnetic bladder (4) is obtained by calculation through the following steps: The radius of the shell (9) of the polishing magnetic capsule (4) is set to be located at its center. Then we have the equation of the circle: According to the principle of force balance, we have: in, This represents the polishing angle corresponding to any straight path. This is the current pressure distribution curve along this straight path. This is the target pressure distribution curve along the straight path. The magnetic force curve of the shell (9) of the polished magnetic bag (4) under the set magnetic field along the straight path; According to the volume formula for magnetic powder particles, we have: in, The radius of the magnetic powder particles in the polishing magnetic capsule (4) is given by the following formula: The volume of the magnetic powder particles in the polishing magnetic capsule (4); Based on the forces acting in a magnetic field, we have: in, The magnetic force experienced by a single magnetic powder particle in the polishing magnetic capsule (4) under a set magnetic field strength. The permeability of vacuum. The volume magnetic susceptibility of the magnetic powder particles is denoted as . Indicates the direction of the magnetic field. For the set magnetic field strength, For magnetic field gradient; Assuming the magnetic powder particles are closely packed in the polished magnetic capsule (4), then they are arranged in a body-centered cubic pattern, and thus: in, The shell (9) of the polished magnetic bladder (4) along The thickness along the axial direction, 0.68 is the packing density of the body-centered cubic unit cell, and 1 represents the unit length. Combining the above equations, we can obtain: in: According to the aforementioned equation of the circle, we can obtain: The coordinates of any point on the inner surface of the shell (9) of the polishing magnetic capsule (4) can be expressed as: According to the Pythagorean theorem, the distance from this point to the center of the circle is: Then the temporary wall thickness function of the shell (9) of the polished magnetic capsule (4) can be obtained. : 。

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