Hemispherical harmonic oscillator inner surface polishing tool and method based on multi-field coupling

Abstract

The invention relates to a hemispherical harmonic oscillator inner surface polishing tool and method based on multi-field coupling, the hemispherical harmonic oscillator inner surface polishing tool comprises a permanent magnet magnetorheological polishing head and a hemispherical harmonic oscillator fixing clamp, and the permanent magnet magnetorheological polishing head comprises a permanent magnet polishing head and a metal clamping rod; the bottom face of the permanent magnet polishing head is an arc surface matched with the radian of the inner surface of the hemispherical harmonic oscillator, a groove is formed in the middle of the permanent magnet polishing head in the horizontal direction, and a liquid injection hole used for injecting magnetorheological fluid in real time is formed between the permanent magnet polishing head and the metal clamping rod in the vertical direction. Four ultrasonic transducers are arranged in the bottom face and the two side faces of the hemispherical harmonic oscillator fixing clamp, and sound fields in the horizontal direction and the vertical direction are added, so that vibration of abrasive particles is promoted, and the machining efficiency is improved. Compared with traditional hemispherical harmonic oscillator magneto-rheological polishing, the size is larger, the effective contact area of magneto-rheological fluid and the inner surface of the harmonic oscillator is increased, meanwhile, due to the spherical shape of the polishing head and the unique movement mode, global machining of the inner surface of the harmonic oscillator is achieved, the uniformity of the inner surface is guaranteed, and the machining efficiency is improved. And the processing efficiency is further improved through the coupling effect of the sound field and the magnetic field.

Description

Technical Field

[0001] The invention relates to the technical field of ultra-precision and high-efficiency polishing processing, and in particular to a tool and method for polishing the inner surface of a hemispherical resonator based on multi-field coupling. Background Art

[0002] As the core component of the hemispherical resonator, the hemispherical resonator is widely used in military, aviation and other fields. Its material is mainly fused quartz crystal. Fused quartz has material properties such as good light transmittance, high hardness and good thermal stability. At the same time, due to the high hardness and complex shape of the resonator material, its processing becomes difficult. There are large residual stresses, surface damage layers and microcracks on the surface of the workpiece after grinding, which affect the navigation accuracy and service life of the hemispherical resonator. Therefore, after precision grinding, the hemispherical resonator needs to be precisely polished to remove the crack layer on the surface of the resonator to improve the quality of the resonator.

[0003] At present, the polishing method for hemispherical resonators is shear rheological polishing or magnetorheological polishing. Shear rheological polishing has problems such as long polishing time and difficulty in ensuring consistent surface accuracy; magnetorheological polishing uses a smaller polishing head to drive magnetorheological fluid to perform small-scale, full-coverage processing on the inner surface of the resonator, which has low processing efficiency and is difficult to ensure the uniformity of the spherical surface. At present, the main method for polishing the inner surface of a hemispherical resonator is to use a small-volume polishing head to perform single-point processing on its inner surface, which has problems such as low processing efficiency, low molding quality, and complex processing process. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a high-efficiency magnetorheological full-domain polishing tool for the inner surface of a hemispherical resonator based on multi-field energy coupling.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A hemispherical resonator inner surface polishing tool based on multi-field coupling, comprising a permanent magnet magnetorheological polishing head and a hemispherical resonator fixing fixture; The permanent magnet magnetorheological polishing head comprises a permanent magnet polishing and a metal clamping rod, the permanent magnet polishing head is fixedly connected to the lower end of the metal clamping rod by gluing, the bottom surface of the polishing head is concentric with the arc of the inner surface of the hemispherical resonator, a groove is opened in the middle horizontal direction of the permanent magnet polishing head, the groove and the arc surface adopt rounded transition and the rounded corner section is concentric with the rounded corner section of the hemispherical resonator, the two side surfaces of the metal clamping rod are provided with clamping surfaces for clamping with a wedge-shaped clamp, and an injection hole for real-time filling of magnetorheological fluid is opened in the vertical direction between the permanent magnet polishing head and the metal clamping rod; The hemispherical resonator fixing fixture is composed of two symmetrical parts. The inner surface is a concentric arc surface that matches the outer surface of the hemispherical resonator. A connecting plate is provided on the side for connecting to a machine tool processing platform, and an ultrasonic transducer is built in to generate ultrasonic waves, thereby promoting the vibration of abrasive particles through the coupling effect of the ultrasonic sound field and the magnetic field generated by the permanent magnet polishing head.

[0006] Furthermore, the width of the middle groove of the permanent magnet polishing head is greater than the inner cylinder diameter of the hemispherical resonator, the height of the groove is greater than the inner cylinder height of the hemispherical resonator, and the arc surface radius of the permanent magnet polishing head is smaller than the inner surface radius of the hemispherical resonator.

[0007] Furthermore, the gap between the arc surface at the bottom of the permanent magnet polishing head and the inner arc surface of the hemispherical resonator is 0.1mm, the gap between the side of the middle groove of the permanent magnet polishing head and the inner cylindrical section of the hemispherical resonator is 0.1mm, the gap between the end face of the groove and the inner cylindrical end face of the hemispherical harmonic is 4mm, and the gap between the transition fillet between the middle groove of the permanent magnet polishing head and the arc surface and the inner fillet section of the hemispherical resonator is 0.1mm.

[0008] Furthermore, the permanent magnet polishing head is formed by hot pressing, bonding or laser 3D printing.

[0009] Furthermore, when the permanent magnet polishing head is formed by hot pressing, the mold used is a cube as a whole, and a cavity is provided inside the mold. The curvature of the bottom surface of the cavity is the same as the curvature of the inner surface of the resonator. An intermediate baffle is provided in the middle position of the bottom of the cavity. The two sides of the intermediate baffle are left-right symmetrical parts. The intermediate baffle is used to form a groove for the permanent magnet polishing head. A cylinder is provided on the top of the intermediate baffle, and the cylinder is used to form an injection hole for the permanent magnet polishing head.

[0010] Furthermore, the hot pressing method comprises the following steps: 1) Mold fixing: clamp and fix the mold; 2) Raw material preparation: NdFeB magnetic powder particles are refined to obtain NdFeB powder with a particle size of about 3.6μm~5.2μm; one or more of polyvinyl alcohol, acrylic acid, polyurethane and other polymers are used as binders to promote the bonding of NdFeB magnetic powder; 3) Mixing: Mix the NdFeB powder and the binder thoroughly and stir evenly, wherein the NdFeB powder accounts for 92%~97% and the rest is the binder; 4) Hot pressing: Place the NdFeB magnetic powder mixed with a binder into a hot pressing mold for a polishing head, heat it to 650°C in a vacuum environment or in a protective inert gas, and apply a pressure of 100Mpa~150Mpa on the top of the mold for 10min~12min to obtain a hot pressed permanent magnet polishing head blank; 5) Sintering treatment: the permanent magnet polishing head blank obtained by hot pressing is sintered at a temperature of 800°C to 1200°C for a time of 3h to 5h; 6) Magnetization treatment: The sintered permanent magnet polishing head blank is placed in a 1.2T~2.0T magnetic field for axial magnetization; 7) Machining: The cylindrical surface of the permanent magnet polishing head blank is machined to reduce the radius of the cylinder and increase its movement angle.

[0011] Furthermore, the bonding method comprises the following steps: 1) Processing of permanent magnet layered workpieces: Use laser cutting to pre-process permanent magnet layered workpieces of different shapes; 2) Bonding molding: Use high-strength structural adhesive to bond each layer of permanent magnet layered workpiece in turn to obtain a patch-type permanent magnet polishing head blank; 3) Grinding and polishing: Finally, the arc surface of the permanent magnet polishing head blank is ground and polished to make it a smooth overall arc, so as to obtain the required permanent magnet polishing head, and the curvature of the arc surface is consistent with the inner surface of the hemispherical resonator.

[0012] Furthermore, the laser 3D printing method comprises the following steps: 1) 3D modeling: Use 3D modeling software to design a three-dimensional model of permanent magnet polishing; 2) Raw material preparation: NdFeB magnetic powder and binder are used as the molding materials of the permanent magnet polishing head, and one or more organic resins such as epoxy resin, acrylic resin, polyurethane, etc. are used as binders to promote the bonding of NdFeB magnetic powder; 3) Refining and cleaning treatment: crush and sieve the particles of NdFeB magnetic powder to obtain NdFeB powder with a particle size of about 2μm~5μm; wash and dry the obtained NdFeB powder to obtain pure NdFeB magnetic powder; 4) Mixing: Mix the NdFeB powder and the binder thoroughly and stir evenly, with the magnetic powder accounting for 80%~85% and the rest being the binder; 5) Adding materials: Add the mixed raw materials into the feeding box of the laser 3D printing equipment; 6) Printing: Import the designed 3D model of the permanent magnet polishing head into the printing equipment software, and print out the permanent magnet polishing head model layer by layer; 7) Sintering treatment: The printed permanent magnet polishing head model is sintered at a temperature of 800°C to 1200°C for 3h to 5h; 8) Magnetization treatment: The sintered permanent magnet polishing head model is placed in a 1.2T~2.0T magnetic field for axial magnetization treatment.

[0013] Furthermore, the ultrasonic transducer is arranged on the two side surfaces and the bottom surface of the hemispherical resonator fixing fixture, with a power of 60W and a frequency of 40KHz.

[0014] A polishing method for a hemispherical resonator inner surface polishing tool based on multi-field coupling, comprising the following methods: 1) Installation of fixtures: Use a swing-arm five-axis machining center for processing, clamp the permanent magnet magnetorheological polishing head on a wedge-shaped fixture, connect it to the machine tool spindle through the wedge-shaped fixture, install the hemispherical resonator fixing fixture on the C-axis machining platform of the machine tool, and clamp and fix the hemispherical resonator; 2) Tool setting: Use a tool setting instrument to set the tool. After the tool setting is completed, the gap between the surface of the permanent magnet polishing head and the inner surface of the hemispherical resonator should be equal; 3) Polishing program writing: Program the motion program of the polishing process, and realize the permanent magnet polishing head to swing at an angle of ±35° at 60 times / min through the reasonable movement of the Z axis and the Y axis and the reasonable swing of the A axis, and the C axis to rotate continuously at 800r / min; 4) Preparation and addition of magnetorheological fluid: Take 100ml of hydroxyl iron powder, clean it thoroughly to remove oil and impurities, and then dry it; add 10ml of silane coupling agent and 15ml of isopropanol and stir them thoroughly to make them fully contact with the hydroxyl iron powder to promote activation; dry the mixture after activation and stirring, add 168ml of silicone oil and 12ml of diamond polishing powder, stir them thoroughly, and then perform ultrasonic dispersion; finally, add 8ml of silicon dioxide and 10ml of bentonite and stir them thoroughly; add the prepared magnetorheological fluid through the injection hole of the polishing head; 5) Polishing: Turn on the ultrasonic transducer, run the polishing program, and polish the inner surface of the hemispherical resonator for 6 hours; 6) Cleaning: After polishing, lift the spindle, remove the hemispherical resonator, put it in a beaker and pour excess alcohol, then put it in an ultrasonic cleaner for 8 to 10 minutes, then rinse it in running deionized water for 2 to 3 minutes, and then put it in a dryer for drying.

[0015] By adopting the above-mentioned technical scheme, the beneficial effects of the present invention are as follows: compared with the traditional small grinding head, the hemispherical resonator magnetorheological polishing head has a larger size, so that the effective contact area between the magnetorheological fluid and the inner surface of the resonator is increased, and at the same time, due to the spherical shape of the polishing head and the unique movement mode, the full-area processing of the inner surface of the resonator is realized, thereby improving the processing efficiency and ensuring the uniformity of the inner surface; the coupling effect of the sound field generated by the hemispherical resonator fixing fixture with a built-in ultrasonic transducer and the magnetic field generated by the permanent magnet polishing head promotes the vibration of the polishing abrasive particles, further improving the processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 It is a schematic diagram of the permanent magnet magnetorheological polishing head of the present invention; Figure 2 is a schematic diagram of a hot pressing mold; Figure 3 It is a schematic diagram of a permanent magnet polishing head blank formed by hot pressing; Figure 4 A schematic diagram of a permanent magnet polishing head blank formed by bonding; Figure 5 Schematic diagram of the permanent magnet polishing head blank after laser 3D printing, hot pressing and bonding machining; Figure 6 It is a schematic diagram of a fixing fixture of a hemispherical resonator of the present invention; Figure 7 This is a schematic diagram of the assembly of the polishing tool and the hemispherical resonator; Figure 8 A schematic diagram of processing a hemispherical resonator according to the present invention; Fig. 9 Schematic diagram of magnetic flux simulation of hot pressing and 3D printing polishing heads. DETAILED DESCRIPTION Specific implementation plan

[0017] like Figure 1 and Figure 6 As shown, the present invention provides a high-efficiency magnetorheological full-domain polishing tool for the inner surface of a hemispherical resonator based on multi-field coupling, comprising: a permanent magnet magnetorheological polishing head 70 and a hemispherical resonator fixing fixture 150; The permanent magnet magnetorheological polishing head 70 comprises a permanent magnet polishing head 50 and a metal clamping rod 10, wherein the permanent magnet polishing head 50 is fixedly connected to the lower end of the metal clamping rod 10 by gluing, and the bottom surface of the permanent magnet polishing head 50 is in a semi-spherical shape, and the bottom surface arc of the permanent magnet polishing head 50 is concentric with the inner surface arc of the hemispherical resonator and has a small radius. A groove 40 with a width greater than the diameter of the inner cylinder of the hemispherical resonator and a height greater than the height of the inner cylinder of the hemispherical resonator is opened in the middle horizontal direction of the permanent magnet polishing head 50, and a fillet 60 is formed at the transition between the groove 40 and the arc surface, and the groove and the arc surface adopt a fillet transition and the fillet section is concentric with the inner fillet section of the hemispherical resonator, and its main function is to ensure that the gap is the same as the inner surface of the hemispherical resonator during the processing, so as to realize the swing processing and rotation processing of the inner surface of the hemispherical resonator without interference. The metal clamping rod 10 is made of 45# steel. The two sides of the metal clamping rod 10 are designed with clamping surfaces 20, which are mainly used to facilitate the clamping of the wedge clamp. The metal clamping rod 10 and the permanent magnet polishing head 50 are bonded together by gluing, and the coaxiality between the two is ensured during the bonding process. A liquid injection hole 30 for real-time injection of magnetorheological fluid is opened in the vertical direction between the permanent magnet polishing head 50 and the metal clamping rod 10; The hemispherical resonator fixing fixture 150 is composed of two symmetrical parts. Its inner surface 160 is a concentric arc surface that matches the outer surface of the hemispherical resonator. A connecting plate 170 is provided on the side for connecting to the machine tool processing platform. Four ultrasonic transducers 180 with a power of 60W and a frequency of 40KHz are built into the left and right side surfaces and the bottom surface for generating ultrasonic waves. The vibration of the polishing abrasive is promoted by adding a sound field, thereby improving the polishing efficiency.

[0018] Figure 7 As shown, it is a schematic diagram of the assembly of the polishing tool and the hemispherical resonator: the hemispherical resonator fixing fixture 150 clamps and fixes the hemispherical resonator 200, and a 0.1mm gap is left between the permanent magnet polishing head 50 and the inner surface of the hemispherical resonator 200, and a 0.1mm gap is left on the side with the central cylinder to facilitate the flow of the polishing liquid in the gap, and a 4mm gap is left between the top surface of the groove of the permanent magnet polishing head and the end surface of the inner cylinder of the hemispherical resonator to avoid interference when the polishing head swings. When working, magnetorheological polishing liquid abrasive particles and water and other media are injected into the interior through the central injection hole of the polishing head to effectively polish the inner surface of the hemispherical resonator and the surface of the central cylinder.

[0019] The permanent magnet polishing head of the present invention is formed by hot pressing, bonding or laser 3D printing.

[0020] like Figure 2As shown, when the permanent magnet polishing head is formed by hot pressing, the mold 80 used is a cube as a whole, and a cavity is provided inside the mold 80. The curvature of the bottom surface 110 of the cavity is the same as the curvature of the inner surface of the resonator. An intermediate baffle 100 is provided in the middle of the bottom of the cavity. The two sides of the intermediate baffle 100 are left-right symmetrical parts. The intermediate baffle 80 is used to form a groove for the permanent magnet polishing head. A cylinder 90 is provided on the top of the intermediate baffle 100, and the cylinder 90 is used to form a liquid injection hole for the permanent magnet polishing head.

[0021] The method of thermoforming comprises the following steps: 1) Mold fixing: clamp and fix the mold; 2) Raw material preparation: NdFeB magnetic powder particles are refined to obtain NdFeB powder with a particle size of about 3.6μm~5.2μm; one or more of polyvinyl alcohol, acrylic acid, polyurethane and other polymers are used as binders to promote the bonding of NdFeB magnetic powder; 3) Mixing: Mix the NdFeB powder and the binder thoroughly and stir evenly, wherein the NdFeB powder accounts for 92%~97% and the rest is the binder; 4) Hot pressing: Place the NdFeB magnetic powder mixed with a binder into a hot pressing mold for a polishing head, heat it to 650°C in a vacuum environment or in a protective inert gas, and apply a pressure of 100Mpa~150Mpa on the top of the mold for 10min~12min. Figure 3 As shown, a hot-pressed permanent magnet polishing head blank 120 is obtained; 5) Sintering treatment: the permanent magnet polishing head blank 120 obtained by hot pressing is sintered at a temperature of 800° C. to 1200° C. for a time of 3 h to 5 h; 6) Magnetization treatment: The sintered permanent magnet polishing head blank 120 is placed in a 1.2T to 2.0T magnetic field for axial magnetization. The magnetic flux simulation diagram is shown in FIG. Fig. 9 As shown; 7) Mechanical processing: The cylindrical surface of the permanent magnet polishing head blank 120 is processed by mechanical processing to obtain the polishing head blank 140 .

[0022] The bonding method comprises the following steps: 1) Processing of permanent magnet layered workpieces: Use laser cutting to pre-process permanent magnet layered workpieces of different shapes; 2) Bonding molding: Use high-strength structural adhesive to bond each layer of permanent magnet layered workpiece in sequence, such as Figure 4 As shown, a patch-type permanent magnet polishing head blank 130 is obtained; 3) Grinding and polishing: Finally, the arc surface of the permanent magnet polishing head blank 130 is ground and polished to make it a smooth overall arc, so as to obtain the desired permanent magnet polishing head 140. The laser 3D printing method includes the following steps: 1) 3D modeling: Use 3D modeling software to design a three-dimensional model of permanent magnet polishing; 2) Raw material preparation: NdFeB magnetic powder and binder are used as the molding materials of the permanent magnet polishing head, and one or more organic resins such as epoxy resin, acrylic resin, polyurethane, etc. are used as binders to promote the bonding of NdFeB magnetic powder; 3) Refining and cleaning treatment: crush and sieve the particles of NdFeB magnetic powder to obtain NdFeB powder with a particle size of about 2μm~5μm; wash and dry the obtained NdFeB powder to obtain pure NdFeB magnetic powder; 4) Mixing: Mix the NdFeB powder and the binder thoroughly and stir evenly, with the magnetic powder accounting for 80%~85% and the rest being the binder; 5) Adding materials: Add the mixed raw materials into the feeding box of the laser 3D printing equipment; 6) Printing: Import the 3D model of the permanent magnet polishing head into the printing equipment software, such as Figure 5 As shown, the permanent magnet polishing head model 140 is printed out layer by layer; 7) Sintering treatment: the printed permanent magnet polishing head model 140 is sintered at a temperature of 800° C. to 1200° C. for a time of 3 h to 5 h; 8) Magnetization treatment: The sintered permanent magnet polishing head model 140 is placed in a 1.2T to 2.0T magnetic field for axial magnetization treatment. The magnetic flux simulation diagram is shown in FIG. Fig. 9 shown. Specific implementation plan

[0023] like Figure 8 As shown, the present invention provides a polishing method for a hemispherical resonator inner surface polishing tool based on multi-field energy coupling, comprising the following methods: 1) Installation of fixtures: Use a swing-arm five-axis machining center for processing, clamp the permanent magnet magnetorheological polishing head 70 on the wedge-shaped fixture 230, connect it to the machine tool spindle 220 through the wedge-shaped fixture 230, install the hemispherical resonator fixing fixture 150 on the machining platform of the C-axis 270 of the machine tool, and clamp and fix the hemispherical resonator 200; 2) Tool setting: Use a tool setting instrument to set the tool. After the tool setting is completed, the gap between the surface of the permanent magnet polishing head and the inner surface of the hemispherical resonator should be equal; 3) Polishing program writing: Program the motion program of the polishing process, and realize the permanent magnet polishing head to swing at an angle of ±35° at 60 times / min through the reasonable movement of the Z axis and the Y axis and the reasonable swing of the A axis, and the C axis to rotate continuously at 800r / min; 4) Preparation and addition of magnetorheological fluid: Take 100ml of hydroxyl iron powder, clean it thoroughly to remove oil and impurities, and then dry it; add 10ml of silane coupling agent and 15ml of isopropanol and stir them thoroughly to make them fully contact with the hydroxyl iron powder to promote activation; dry the mixture after activation and stirring, add 168ml of silicone oil and 12ml of diamond polishing powder, stir them thoroughly, and then disperse them ultrasonically; finally, add 8ml of silicon dioxide and 10ml of bentonite and stir them thoroughly to effectively improve the viscosity and anti-sedimentation properties of the magnetorheological polishing fluid. After the magnetorheological fluid is prepared, add it through the injection hole of the polishing head; 5) Polishing: Turn on the ultrasonic transducer, run the polishing program, and polish the inner surface of the hemispherical resonator for 6 hours; 6) Cleaning: After polishing, lift the spindle, remove the hemispherical resonator, put it in a beaker and pour excess alcohol, then put it in an ultrasonic cleaner for 8 to 10 minutes, then rinse it in running deionized water for 2 to 3 minutes, and finally put it in a dryer for drying.

[0024] The above describes a specific embodiment of the present invention, but those skilled in the art should understand that this is only an example. Those skilled in the art can make various changes or modifications to this embodiment without departing from the principle and essence of the present invention, but these changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A hemispherical resonator inner surface polishing tool based on multi-field coupling, characterized in that: It includes a permanent magnet magnetorheological polishing head and a hemispherical resonator fixing fixture; The permanent magnet magnetorheological polishing head comprises a permanent magnet polishing head and a metal clamping rod, the permanent magnet polishing head is fixedly connected to the lower end of the metal clamping rod by gluing, the bottom surface of the polishing head is concentric with the arc of the inner surface of the hemispherical resonator, a groove is horizontally provided in the middle of the permanent magnet polishing head, the groove and the arc surface adopt a rounded transition and the rounded corner section is concentric with the rounded corner section of the hemispherical resonator, the two side surfaces of the metal clamping rod are provided with clamping surfaces for clamping with a wedge-shaped clamp, and the permanent magnet polishing head and the metal clamping rod are vertically provided with injection holes for real-time injection of magnetorheological fluid; The hemispherical resonator fixing fixture is composed of two symmetrical parts. The inner surface is a concentric arc surface that matches the outer surface of the hemispherical resonator. A connecting plate is provided on the side for connecting to a machine tool processing platform, and an ultrasonic transducer is built in to generate ultrasonic waves, thereby promoting the vibration of abrasive particles through the coupling effect of the ultrasonic sound field and the magnetic field generated by the permanent magnet polishing head.

2. The hemispherical resonator inner surface polishing tool based on multi-field coupling according to claim 1 is characterized in that: The width of the middle groove of the permanent magnet polishing head is greater than the inner cylinder diameter of the hemispherical resonator, the height of the groove is greater than the inner cylinder height of the hemispherical resonator, and the arc surface radius of the permanent magnet polishing head is smaller than the inner surface radius of the hemispherical resonator.

3. The hemispherical resonator inner surface polishing tool based on multi-field coupling according to claim 2 is characterized in that: The gap between the bottom arc surface of the permanent magnet polishing head and the inner arc surface of the hemispherical resonator is 0.1mm, the gap between the side of the middle groove of the permanent magnet polishing head and the inner cylindrical section of the hemispherical resonator is 0.1mm, the gap between the top surface of the groove and the inner cylindrical end surface of the hemispherical harmonic is 4mm, and the gap between the transition fillet between the middle groove of the permanent magnet polishing head and the arc surface and the inner fillet section of the hemispherical resonator is 0.1mm.

4. The hemispherical resonator inner surface polishing tool based on multi-field coupling according to claim 1 is characterized in that: The permanent magnet polishing head is formed by hot pressing, bonding or laser 3D printing.

5. The hemispherical resonator inner surface polishing tool based on multi-field coupling according to claim 4 is characterized in that: When the permanent magnet polishing head is formed by hot pressing, the mold used is a cube as a whole, and a cavity is provided inside the mold. The curvature of the bottom surface of the cavity is the same as the curvature of the inner surface of the resonator. An intermediate baffle is provided in the middle position of the bottom of the cavity. The two sides of the intermediate baffle are left-right symmetrical parts. The intermediate baffle is used to form a groove of the permanent magnet polishing head. A cylinder is provided on the top of the intermediate baffle, and the cylinder is used to form an injection hole of the permanent magnet polishing head.

6. According to claim 4, a high-efficiency magnetorheological full-range polishing tool for the inner surface of a hemispherical resonator based on multi-field energy coupling is characterized by: The method of thermoforming comprises the following steps: 1) Mold fixing: clamp and fix the mold; 2) Raw material preparation: NdFeB magnetic powder particles are refined to obtain NdFeB powder with a particle size of about 3.6μm~5.2μm; one or more of polyvinyl alcohol, acrylic acid, polyurethane and other polymers are used as binders to promote the bonding of NdFeB magnetic powder; 3) Mixing: Mix the NdFeB powder and the binder thoroughly and stir evenly, wherein the NdFeB powder accounts for 92%~97% and the rest is the binder; 4) Hot pressing: Place the NdFeB magnetic powder mixed with a binder into a hot pressing mold for a polishing head, heat it to 650°C in a vacuum environment or in a protective inert gas, and apply a pressure of 100Mpa~150Mpa on the top of the mold for 10min~12min to obtain a hot pressed permanent magnet polishing head blank; 5) Sintering treatment: the permanent magnet polishing head blank obtained by hot pressing is sintered at a temperature of 800°C to 1200°C for a time of 3h to 5h; 6) Magnetization treatment: The sintered permanent magnet polishing head blank is placed in a 1.2T~2.0T magnetic field for axial magnetization; 7) Machining: The cylindrical surface of the permanent magnet polishing head blank is machined to reduce the radius of the cylinder and increase its movement angle.

7. According to claim 4, a high-efficiency magnetorheological full-range polishing tool for the inner surface of a hemispherical resonator based on multi-field energy coupling is characterized by: The bonding method comprises the following steps: 1) Processing of permanent magnet layered workpieces: Use laser cutting to pre-process permanent magnet layered workpieces of different shapes; 2) Bonding molding: Use high-strength structural adhesive to bond each layer of permanent magnet layered workpiece in turn to obtain a patch-type permanent magnet polishing head blank; 3) Grinding and polishing: Finally, the arc surface of the permanent magnet polishing head blank is ground and polished to make it a smooth overall arc, so as to obtain the required permanent magnet polishing head, and the curvature of the arc surface is consistent with the inner surface of the hemispherical resonator.

8. According to claim 4, a high-efficiency magnetorheological full-range polishing tool for the inner surface of a hemispherical resonator based on multi-field energy coupling is characterized by: The laser 3D printing method comprises the following steps: 1) 3D modeling: Use 3D modeling software to design a three-dimensional model of permanent magnet polishing; 2) Raw material preparation: NdFeB magnetic powder and binder are used as the molding materials of the permanent magnet polishing head, and one or more organic resins such as epoxy resin, acrylic resin, polyurethane, etc. are used as binders to promote the bonding of NdFeB magnetic powder; 3) Refining and cleaning treatment: crush and sieve the particles of NdFeB magnetic powder to obtain NdFeB powder with a particle size of about 2μm~5μm; wash and dry the obtained NdFeB powder to obtain pure NdFeB magnetic powder; 4) Mixing: Mix the NdFeB powder and the binder thoroughly and stir evenly, with the magnetic powder accounting for 80%~85% and the rest being the binder; 5) Adding materials: Add the mixed raw materials into the feeding box of the laser 3D printing equipment; 6) Printing: Import the designed 3D model of the permanent magnet polishing head into the printing equipment software, and print out the permanent magnet polishing head model layer by layer; 7) Sintering treatment: The printed permanent magnet polishing head model is sintered at a temperature of 800°C to 1200°C for 3h to 5h; 8) Magnetization treatment: The sintered permanent magnet polishing head model is placed in a 1.2T~2.0T magnetic field for axial magnetization treatment.

9. According to claim 1, a high-efficiency magnetorheological full-range polishing tool for the inner surface of a hemispherical resonator based on multi-field energy coupling, characterized in that: The ultrasonic transducer is arranged on the two side surfaces and the bottom surface of the hemispherical resonator fixing fixture, and the transducer power is 60W and the frequency is 40KHz.

10. A polishing method for the inner surface polishing tool of a hemispherical resonator based on multi-field coupling according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: 1) Installation of fixtures: Use a swing-arm five-axis machining center for processing, clamp the permanent magnet magnetorheological polishing head on a wedge-shaped fixture, connect it to the machine tool spindle through the wedge-shaped fixture, install the hemispherical resonator fixing fixture on the C-axis machining platform of the machine tool, and clamp and fix the hemispherical resonator; 2) Tool setting: Use a tool setting instrument to set the tool. After the tool setting is completed, the gap between the outer surface of the permanent magnet polishing head and the inner surface of the hemispherical resonator should be equal; 3) Polishing program writing: Program the motion program of the polishing process, and realize the permanent magnet polishing head to swing at an angle of ±35° at 60 times / min through the reasonable movement of the Z axis and the Y axis and the reasonable swing of the A axis, and the C axis to rotate continuously at 800r / min; 4) Preparation and addition of magnetorheological fluid: Take 100ml of hydroxyl iron powder, clean it thoroughly to remove oil and impurities, and then dry it; add 10ml of silane coupling agent and 15ml of isopropanol and stir them thoroughly to make them fully contact with the hydroxyl iron powder to promote activation; dry the mixture after activation and stirring, add 168ml of silicone oil and 12ml of diamond polishing powder, stir them thoroughly, and then perform ultrasonic dispersion; finally, add 8ml of silicon dioxide and 10ml of bentonite and stir them thoroughly; add the prepared magnetorheological fluid through the injection hole of the polishing head; 5) Polishing: Turn on the ultrasonic transducer, run the polishing program, and polish the inner surface of the hemispherical resonator for 6 hours; 6) Cleaning: After polishing, lift the spindle, remove the hemispherical resonator, put it in a beaker and pour excess alcohol, then put it in an ultrasonic cleaner for 8 to 10 minutes, then rinse it in running deionized water for 2 to 3 minutes, and then put it in a dryer to dry.

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