A jet hydrostatic magnetorheological polishing device and method

Abstract

The present invention discloses a jet hydrodynamic magnetorheological polishing device and method, which mainly include: a base and a workpiece dynamic structure. The workpiece dynamic structure refers to the workpiece under the action of the workpiece rotation mechanism to realize the workpiece dynamic pressure cover around the rotating main axis, the dynamic pressure cover is provided with a concave portion at the installation position of the workpiece, which is used to control the size and distribution of the jet hydrodynamic fluid dynamic pressure, and form fluid dynamic pressure under the action of dynamic magnetic field and fluid extrusion, effectively enhancing the shear force and positive pressure acting on the workpiece surface. This process method is suitable for the flattening and ultra-smooth surface polishing of optical elements, electronic and microelectronic substrates.

Description

Technical Field

[0001] The invention relates to the technical field of polishing technology, and more specifically, to a jet fluid pressure magnetorheological polishing device and method. Background Art

[0002] Today, countries around the world are in a new stage of information development. The development and application of advanced technologies such as 5G, XR, artificial intelligence (AI), the Internet of Things and cloud computing, and the rapid development of electronic information technology are driving the world economic system towards the development of a digital economy. For this reason, the development of electronic information technology has become a standard for measuring the strength of a country's cutting-edge scientific and technological level, among which the development of integrated circuit chip (IC) technology based on semiconductor materials is particularly critical.

[0003] Traditional semiconductor materials such as single crystal silicon, silicon carbide, gallium arsenide, sapphire, etc. generally need to go through processes such as crystal rod growth, slicing, chamfering, grinding, and polishing. To meet the requirements of industrial production, their surface accuracy needs to reach ultra-smoothness (roughness Ra is below 1nm), and the surface accuracy also has high requirements (surface accuracy is below 0.5μm). The existing domestic and foreign processing devices for semiconductor wafers are mainly high-efficiency grinding, ultra-precision polishing, chemical mechanical polishing, etc. Cluster magnetorheological polishing is a technology that can be used for flattening of semiconductor substrates. It uses magnetorheological fluid to form a flexible polishing pad to remove material from the processing surface. The existing cluster magnetorheological grinding and polishing device is equipped with at least one magnet assembly under the polishing disk, and each magnet assembly includes at least two magnets arranged according to a preset rule, so that the flexible polishing pad formed by the magnetorheological polishing fluid completely covers the surface of the workpiece. However, the polishing intensity of the device is not high and the processing efficiency is relatively low. At the same time, when the workpiece is in compression contact with the magnetorheological polishing pad, due to the relative movement between the workpiece and the polishing disk, the squeezed magnetic particles and abrasives will be thrown out of the processing area under the action of centrifugal force, thereby reducing the polishing force and polishing quality. It is difficult to maintain the processing stability of the workpiece, which restricts the further development and application of this process. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the existing magnetorheological polishing device, such as insufficient polishing force and poor polishing quality, because the squeezed magnetic particles and abrasives will be thrown out of the processing area under the action of centrifugal force. A jet hydrostatic magnetorheological polishing device and method are provided, so that when the polishing liquid flows through the processing area, the shear force and positive pressure acting on the surface of the workpiece can be increased due to the structure of the concave portion, thereby improving the polishing force and polishing quality. The use of this polishing device and method can improve the processing quality and processing efficiency of the workpiece surface.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] On the one hand, the present invention provides a jet hydrodynamic magnetorheological polishing device, comprising a base, a workpiece power structure is arranged on the base, and a magnet capable of covering a processing surface is arranged below the workpiece power structure;

[0007] The workpiece power structure includes a dynamic pressure cover and a workpiece rotation mechanism, the workpiece rotation mechanism is used to rotate the dynamic pressure cover, the dynamic pressure cover is provided with a concave portion at the installation position of the workpiece, the slope of the concave portion can be adjusted according to actual conditions, so as to control the size and distribution of the hydrodynamic pressure of the jet hydraulic fluid;

[0008] In addition, the device also includes a polishing disk, a polishing liquid inlet and a polishing liquid outlet. The top of the polishing disk is sealed and connected to the dynamic pressure top cover to form a cavity. The processing surface of the workpiece to be polished abuts against the cavity. The polishing liquid inlet is arranged at the geometric center position of the bottom of the polishing disk and is connected to the cavity. The polishing liquid outlet is arranged on the side wall of the polishing disk and is connected to the cavity. The polishing liquid inlet is provided with a peristaltic pump for inputting the polishing liquid. Under the magnetorheological effect of the magnet, the polishing liquid forms a magnetorheological polishing pad at the position of the workpiece to be polished.

[0009] On the other hand, the present invention also discloses a jet hydrodynamic magnetorheological polishing method, which includes the working principle of the polishing device and specifically includes the following steps:

[0010] Step S1, according to the characteristics of the workpiece to be processed, select a magnet with a suitable magnetic field strength, and install it on the lower part of the workpiece power structure in a manner of adjacent same magnetic poles or adjacent different magnetic poles, and at the same time, install the polishing disc on the base;

[0011] Step S2, clamping the workpiece on the lower concave portion of the dynamic pressure top cover by vacuum adsorption or waxing, so that the processing surface of the workpiece is located within the polishing range of the polishing device;

[0012] Step S3, installing a sealing structure between the dynamic pressure cover and the polishing plate, and adjusting the dynamic pressure cover until the bottom surface of the lower concave portion of the dynamic pressure cover is 1-5 mm away from the polishing plate;

[0013] Step S4, adding 1%-10% micron-sized abrasive, 15%-60% micron-sized carbonyl iron powder, 2%-10% dispersant, and 1%-10% stabilizer to deionized water, stirring for 5-20 minutes with a magnetic stirrer, and then vibrating by ultrasonic waves for 5-20 minutes to form a magnetorheological polishing liquid;

[0014] Step S5, injecting the magnetorheological polishing liquid prepared in step S4 from the polishing liquid inlet through a peristaltic pump, and the polishing liquid flows out from the polishing liquid outlet, and the polishing liquid forms a magnetorheological polishing pad under the magnetorheological effect of the magnet;

[0015] Step S6, start the workpiece rotating mechanism to drive the dynamic pressure top cover to rotate at a speed of 10-100r / min. The magnetorheological polishing fluid on the upper end of the polishing disk forms a magnetorheological polishing pad with viscoelasticity under the excitation of the composite magnetic field formed by the magnet. The workpiece and the magnetorheological polishing pad are in dynamic pressure contact in the lower recessed area. The relative movement between the workpiece and the magnetorheological polishing pad can achieve efficient, ultra-smooth and damage-free magnetorheological polishing of the workpiece.

[0016] Furthermore, one or more recesses are provided on the dynamic pressure top cover. When the number of recesses is greater than one, they are rotationally symmetrically arranged along the geometric center of the dynamic pressure top cover so that the dynamic pressure top cover can maintain force balance as much as possible when rotating.

[0017] Furthermore, the device also includes a magnetic field power structure, the magnet is arranged on the top surface of the magnetic field power structure, the magnetic field power structure includes a magnet rotating shaft and a first motor fixed on the base, the output shaft of the first motor is connected to the magnet rotating shaft through a transmission part, and drives the magnet rotating shaft to rotate. Preferably, the transmission part includes a driving pulley connected to the output shaft of the first motor, a driven pulley meshingly connected to the magnet rotating shaft, and a synchronous belt sleeved on the side walls of the driving pulley and the driven pulley.

[0018] Furthermore, there is a gap between the top of the magnet rotating shaft and the bottom surface of the polishing disk, one or more magnets are arranged on the top of the magnet rotating shaft, and the distance between the magnet and the bottom surface of the polishing disk is any value between 0.5mm and 5mm. The magnet is an annular permanent magnet, and the magnetic field strength of the annular permanent magnet is any value between 2000Gs and 6000Gs. The difference between the inner and outer diameters (i.e., the minimum inner diameter and the maximum outer diameter) of the annular permanent magnet is greater than the bottom surface area of ​​the workpiece, ensuring that the magnetorheological polishing pad generated by the annular permanent magnet can completely cover the processing area. It should be noted that when multiple annular permanent magnets are provided, the magnetic pole directions of two adjacent annular permanent magnets can be arranged in the same direction or in opposite directions.

[0019] Furthermore, the workpiece rotating mechanism includes a second motor and a rotating spindle, one end of the rotating spindle is connected to the output shaft of the second motor, and the other end is connected to the geometric center position of the dynamic pressure top cover.

[0020] Furthermore, the dynamic pressure cover is connected to the bottom of the rotating spindle through a first fastening screw, and can rotate relative to the polishing disc at a speed of 10-100r / min. A second sealing ring is provided between the top of the polishing disc and the dynamic pressure cover.

[0021] Further, the workpiece power structure also includes a workpiece self-rotation mechanism, which includes a third motor, a third motor disk, a convex bottom plate and a workpiece disk, wherein the convex bottom plate is arranged on the lower concave portion and has a through hole in the middle thereof, the third motor is mounted on the convex bottom plate, the third motor shaft of the third motor passes through the convex bottom plate and is connected to the workpiece disk, and the workpiece disk is sealed and connected to the dynamic pressure top cover via a first sealing ring. Preferably, the third motor is fixedly connected to the convex bottom plate via a second fastening screw, and the lower end of the convex bottom plate is fixed to the dynamic pressure top cover via a third fastening screw.

[0022] Furthermore, it also includes a bottom plate, the base is fixedly connected to the bottom plate, an arch-shaped bracket is also fixedly connected to the bottom plate, and the linear displacement mechanism is fixed on the arch-shaped bracket.

[0023] Furthermore, the workpiece power structure also includes a linear displacement mechanism, which includes a guide rail panel and a fourth motor. A vertical travel guide is provided on the surface of the guide rail panel. The workpiece rotation mechanism is slidably connected to the travel guide and connected to the output shaft of the fourth motor. Driven by the fourth motor, the workpiece rotation mechanism can move up and down along the travel guide, thereby adjusting the distance between the dynamic pressure top cover and the polishing disk.

[0024] The beneficial effects of the present invention are:

[0025] 1. The dynamic pressure top cover structure is provided with a concave portion. When the magnetorheological polishing fluid flows through the processing / polishing area where the concave portion is located, the magnetorheological polishing fluid flows from the large opening to the small opening and is squeezed to form a more stable magnetorheological polishing pad, which effectively enhances the shear force and positive pressure acting on the workpiece surface, realizes the real-time update of carbonyl iron powder particles and abrasive particles, restores the geometric shape and polishing ability of the flexible polishing pad, and improves the polishing effect;

[0026] 2. A magnetic field power structure is adopted to make the magnet and the polishing disc rotate relative to each other, and the magnet forms a stable dynamic magnetic field. Under the action of the dynamic magnetic field, the magnetorheological polishing fluid can be controlled to form a stable magnetorheological polishing pad. In addition, the magnetorheological polishing fluid can be refluxed and renewed under the action of the dynamic magnetic field and the flow of the magnetorheological polishing fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the jet hydrodynamic magnetorheological polishing device of the present invention;

[0028] Figure 2 for Figure 1 Sectional view at AA in the middle;

[0029] Figure 3 A schematic diagram of the polishing process of the jet hydrostatic magnetorheological polishing device of the present invention;

[0030] Figure 4 for Figure 3 Cross-section at the middle BB;

[0031] Figure 5 for Figure 3 Sectional view at CC;

[0032] Figure 6 The present invention is a flow chart of the jet fluid pressure magnetorheological polishing method.

[0033] In the attached figure:

[0034] 1-bottom plate, 2-base, 3-first deep groove ball bearing, 4-second deep groove ball bearing, 5-first annular permanent magnet, 6-second annular permanent magnet, 7-polishing disc, 8-magnetorheological polishing pad, 9-polishing liquid outlet, 11-dynamic pressure top cover, 13-workpiece disk, 14-convex bottom plate, 15-third motor shaft, 16-third motor, 17-rotating spindle, 18-first fastening screw, 19-second fastening screw, 20-first coupling, 21-third fastening screw, 22-first sealing ring, 23-second sealing ring, 24-fourth fastening screw, 25-first motor, 26-fifth fastening screw, 27-first motor rotating shaft, 28-second coupling, 29-pulley rotating shaft, 30-driving pulley, 31-fastening nut, 32-synchronous belt, 33-sixth fastening screw, 34-driven pulley, 35-seventh fastening screw, 36-polishing liquid inlet, 37-pulley fastener, 38-magnet rotating shaft, 39-bearing inner sleeve, 40-flange, 41-bow bracket, 42-guide panel, 43-travel guide, 44-second motor, 45-fourth motor.

[0035] The direction of the arrow in the figure indicates the flow direction of the polishing liquid. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific implementation methods. The drawings are only used for exemplary description and cannot be understood as limiting the present invention. In order to better illustrate the present embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0037] The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "front", "rear", "left", "right" and the like indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for exemplary explanations and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances. In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0038] Embodiment 1:

[0039] See also Figures 1 to 5 This embodiment provides a jet fluid pressure magnetorheological polishing device, which is mainly used for grinding and polishing the surface of a wafer, and includes a base 2, and a magnetic field power structure and a workpiece power structure arranged on the base 2.

[0040] The magnetic field power structure includes a magnet rotating shaft 38 and a first motor 25, and the magnet rotating shaft 38 is a cylindrical cavity structure. The first motor 25 is fixedly connected to the base 2 through the fifth screw 26, and the first motor rotating shaft 27 is connected to the pulley transmission shaft 29 through the second coupling 28. The pulley transmission shaft 29 is connected to the driving pulley 30, the synchronous belt 32, and the driven pulley 34 in sequence. The driven pulley 34 is meshed and connected with the magnet rotating shaft 38 to drive the magnet rotating shaft 38 to rotate. A pulley fastener 37 is fixed to the bottom of the magnet rotating shaft 38 through the seventh screw 35, which is used to fasten the driven pulley 34 and the magnet rotating shaft 38 to prevent the two from slipping.

[0041] The workpiece power structure includes a dynamic pressure cover 11, a linear displacement mechanism capable of adjusting the height position of the dynamic pressure cover 11, a workpiece rotation mechanism capable of driving the dynamic pressure cover 11 to rotate, and a workpiece self-rotation mechanism capable of driving the workpiece to rotate. The workpiece rotation mechanism includes a second motor 44 and a rotating spindle 17, one end of the rotating spindle 17 is connected to the output shaft of the second motor 44, and the other end is connected to the geometric center position of the dynamic pressure cover 11 and fixed by a first fastening screw 18. The dynamic pressure cover 11 is provided with 6 recesses, which are equidistantly arranged around the geometric center circumference of the dynamic pressure cover 11, and the center of the recess is provided with a working hole for inserting the workpiece to be polished. It should be noted that the number of recesses is not specifically limited, and the number of recesses can be increased within a reasonable range to increase the number of workpieces processed simultaneously and improve the processing efficiency. Preferably, when the number of recesses is greater than one, they are arranged rotationally symmetrically along the geometric center of the dynamic pressure cover 11, so that the dynamic pressure cover 11 can maintain force balance as much as possible when rotating. The workpiece self-rotation mechanism is arranged on each concave part, and any workpiece self-rotation mechanism includes a convex bottom plate 14 with a through hole in the middle, and the convex bottom plate 14 is fixed to the dynamic pressure top cover 11 by a third fastening screw 21. The third motor 16 is fixed to the top surface of the convex bottom plate 14 by a second fastening screw 19. After installation, the third motor shaft 15 of the third motor 16 passes through the through hole and is connected to the first coupling 20, and the first coupling 20 is connected to the workpiece disk 13. The workpiece disk 13 is installed in the working hole of the concave part, and its bottom surface fixes the workpiece to be polished by vacuum adsorption. A first sealing ring 22 is provided between the workpiece disk 13 and the dynamic pressure top cover 11.

[0042] The workpiece dynamic structure also includes a polishing disc 7, the top surface of which is open and is arranged below the dynamic pressure cover 11, and is sealed with the dynamic pressure cover 11 through a second sealing ring 23. The dynamic pressure cover 11 and the polishing disc 7 form a sealed cavity structure, and a polishing liquid inlet 36 is provided at the bottom of the polishing disc 7. In this embodiment, the polishing liquid inlet 36 is arranged at the geometric center of the bottom surface of the polishing disc 7, and the polishing liquid inlet 36 is connected to a peristaltic pump (not shown in the figure), and the peristaltic pump is used to input the polishing liquid into the sealed cavity structure. A polishing liquid outlet 9 is provided on the side wall of the polishing disc 7, and the polishing liquid outlet 9 is connected to the sealed cavity structure for discharging the polishing liquid.

[0043] The top of the magnet rotating shaft 38 is provided with a first annular permanent magnet 5 and a second annular permanent magnet 6. The first annular permanent magnet 5 is arranged on the inner side, and the distance between its inner edge and the rotating main shaft 17 is smaller than the distance between the inner side edge of the workpiece and the rotating main shaft 17. Similarly, the distance between the outer edge of the second annular permanent magnet 6 and the rotating main shaft 17 is larger than the distance between the outer side edge of the workpiece and the rotating main shaft 17, so as to ensure that the top area of ​​the first annular permanent magnet 5 and the second annular permanent magnet 6 can cover the bottom surface of the workpiece, that is, the processing surface. When the polishing liquid flows in the sealed cavity structure, a magnetorheological polishing pad 8 can be formed under the magnetorheological effect of the magnet, and the magnetorheological polishing pad 8 can completely cover the bottom surface of the workpiece, that is, the processing surface.

[0044] Embodiment 2:

[0045] This embodiment provides a jet hydrodynamic magnetorheological polishing method, using the jet hydrodynamic magnetorheological polishing device as described in the first embodiment, referring to Figure 6 , the polishing method comprises the following steps:

[0046] Step S1, according to the characteristics of the workpiece to be processed, select the first annular permanent magnet 5 and the second annular permanent magnet 6 with appropriate magnetic field strength, install them on the upper end of the magnet rotating shaft 38 in a manner of adjacent same magnetic poles, and install the polishing disc 7 on the base 2;

[0047] Step S2, clamping the workpiece on the workpiece plate 13 by vacuum adsorption, so that the workpiece is located in the processing area of ​​the polishing device;

[0048] Step S3, installing the dynamic pressure cover 11 on the lower end of the rotating spindle 17, installing the second sealing ring 23 between the dynamic pressure cover 11 and the polishing plate 7, and starting the linear displacement mechanism to lower the dynamic pressure cover 11 until the distance between it and the polishing plate 7 is 1 mm;

[0049] Step S4, adding 1% of micron-sized abrasive, 15% of micron-sized carbonyl iron powder, 1% of dispersant, and 1% of stabilizer to deionized water, stirring for 20 minutes with a magnetic stirrer, and then vibrating by ultrasonic waves for 20 minutes to form a magnetorheological polishing liquid;

[0050] Step S5, injecting the magnetorheological polishing liquid prepared in step S4 from the polishing liquid inlet 36 through a peristaltic pump, and the polishing liquid flows out from the polishing liquid outlet 9, and the polishing liquid forms a magnetorheological polishing pad 8 under the magnetorheological effect of the first annular permanent magnet 5 and the second annular permanent magnet 6;

[0051] Step S6, start the third motor 16 to drive the workpiece disk 13 to rotate at a speed of 50r / min, start the second motor 44 to drive the dynamic pressure cover 11 to rotate around the rotating spindle 17 at a speed of 10r / min, and start the first motor 25 to drive the magnet rotating shaft 38 and the magnet to rotate relative to the polishing disk 7 at a speed of 10r / min. It should be noted that the rotation direction of the magnet is opposite to the rotation direction of the dynamic pressure cover 11. Under the excitation of the composite magnetic field formed by the magnet, the magnetorheological polishing liquid on the upper end of the polishing disk 7 forms a magnetorheological polishing pad 8 with viscoelasticity. The workpiece is in dynamic pressure contact with the magnetorheological polishing pad 8 in the lower concave area. The relative movement of the workpiece and the magnetorheological polishing pad 8 can achieve efficient, ultra-smooth and damage-free magnetorheological polishing of the workpiece.

[0052] Embodiment three:

[0053] See also Figure 1 , Figure 3 as well as Figure 4 On the basis of the first embodiment, the jet fluid pressure magnetorheological polishing device further includes a base plate 1, and the base 2 is fixed to the base plate 1 by an eighth screw 31. In addition, an arch bracket 41 is provided, the bottom end of the arch bracket 41 is integrally connected to the base plate 1, and the other end of the arch bracket 41 is connected to the linear displacement mechanism. The linear displacement mechanism includes a guide rail panel 42 and a fourth motor 45, and the surface of the guide rail panel 42 is provided with a vertical travel guide rail 43. The mounting frame of the second motor 44 is slidably connected to the travel guide rail 43, and the mounting frame is connected to the output end of the fourth motor 45. When the fourth motor 45 is started, the mounting frame of the second motor 44 can move up and down along the travel guide rail 43. Since the second motor 44, the rotating spindle 17 and the dynamic pressure top cover 11 are fixedly connected, the height of the dynamic pressure top cover 11 can be adjusted, and the distance between the workpiece and the magnetorheological polishing pad 8 can be changed. The workpiece is clamped on the workpiece disk 13 by waxing, so that the workpiece is located in the processing area of ​​the polishing device. After the dynamic pressure top cover 11 and the polishing disk 7 are sealed and installed, the fourth motor 45 is started to lower the dynamic pressure top cover 11 to a distance of 5 mm between it and the polishing disk 7.

[0054] A magnetorheological polishing fluid was prepared by adding 10% micron-sized abrasive, 60% micron-sized carbonyl iron powder, 10% dispersant and 10% stabilizer to deionized water, stirring with a magnetic stirrer for 5 minutes and then vibrating with ultrasonic waves for 5 minutes.

[0055] The configured magnetorheological polishing liquid is injected from the polishing liquid inlet 36 into the sealed cavity formed by the dynamic pressure top cover 11 and the polishing disk 7 through a peristaltic pump (not shown in the figure). The polishing liquid forms a magnetorheological polishing pad 8 under the magnetorheological effect of the magnet and then flows out from the polishing liquid outlet 9.

[0056] After the sealing chamber is filled with polishing liquid, the third motor 16 is started to drive the workpiece disk 13 to rotate at a speed of 500 r / min, the second motor 44 is started to drive the dynamic pressure top cover to rotate around the rotating spindle 17 at a speed of 100 r / min, and the first motor 25 is started to drive the magnet rotating shaft 38 and the magnet to rotate relative to the polishing disk 7 at a speed of 50 r / min. Under the excitation of the composite magnetic field formed by the magnet, the magnetorheological polishing liquid on the upper end of the polishing disk 7 forms a magnetorheological polishing pad 8 with viscoelasticity. The workpiece is in dynamic pressure contact with the magnetorheological polishing pad 8 in the lower recessed area to polish and grind the bottom surface of the workpiece.

[0057] Embodiment 4:

[0058] See also Figures 1 to 3 ,as well as Figure 5 On the basis of any of the above-mentioned jet fluid pressure magnetorheological polishing devices, a gap is left between the top of the magnet rotating shaft 38 and the bottom surface of the polishing plate 7 in this embodiment. The base 2 and the polishing plate 7 are connected by a fourth fastening screw 24. The fourth fastening screw 24 can be screwed to adjust the distance between the base 2 and the polishing plate 7, and then adjust the distance between the polishing plate 7 and the magnet installed on the top surface of the magnet rotating shaft 38, so that the distance is adjustable within the range of 0.5-5mm.

[0059] The magnet rotating shaft 38 is a hollow cylindrical structure, and the peristaltic pump (not shown in the figure) is installed in the cavity of the magnet rotating shaft 38 and connected to the polishing liquid inlet 36. The outer wall of the magnet rotating shaft 38 is provided with a first deep groove ball bearing 3 and a second deep groove ball bearing 4, and the first deep groove ball bearing 3 and the second deep groove ball bearing 4 are fixed by a flange 40 and a bearing inner sleeve 39, wherein the flange 40 is fixedly connected to the base 2 by a sixth screw 33. The first deep groove ball bearing 3 and the second deep groove ball bearing 4 mainly bear radial loads, and can also bear radial loads and axial loads at the same time. When they only bear radial loads, the contact angle is zero. When the deep groove ball bearing has a large radial clearance, it has the performance of an angular contact bearing and can withstand a large axial load. The friction coefficient of the deep groove ball bearing is very small, and the limit speed is also very high, so it can withstand the rotation speed of the magnet rotating shaft 38 up to 50r / min.

[0060] According to the characteristics of the workpiece, a first annular permanent magnet 5 and a second annular permanent magnet 6 with a magnetic field strength of 2000Gs are selected, and the two magnets are installed on the top surface of the magnet rotating shaft 38. The two magnets are installed in a manner of adjacent opposite magnetic poles. The fourth fastening screw 24 is adjusted so that the distance between the top surface of the magnet and the bottom surface of the polishing disk 7 is 0.5mm. Then the workpiece is fixedly clamped on the workpiece disk 13, and a first sealing ring 22 is installed on the outer periphery of the workpiece disk 13 so that the workpiece disk 13 is sealed and connected with the dynamic pressure top cover 11, and at the same time, it is ensured that the workpiece is located in the processing area, that is, the workpiece is located in the area formed by the first annular permanent magnet 5 and the second annular permanent magnet 6. Next, the dynamic pressure top cover 11 is installed at the lower end of the rotating spindle 17, and a second sealing ring 23 is installed between the dynamic pressure top cover 11 and the polishing disk 7. The linear displacement mechanism is started to lower the dynamic pressure top cover 11 to a distance of 1mm from the polishing disk 7. The magnetorheological polishing liquid as described in Example 2 or Example 3 is configured and injected into the polishing liquid inlet 36 through a peristaltic pump.

[0061] After the sealing chamber is filled with polishing liquid, the third motor 16 is started to drive the workpiece disk 13 to rotate at a speed of 200 r / min, the second motor 44 is started to drive the dynamic pressure top cover to rotate around the rotating spindle 17 at a speed of 50 r / min, and the first motor 25 is started to drive the magnet rotating shaft 38 and the magnet to rotate relative to the polishing disk 7 at a speed of 50 r / min. Under the excitation of the composite magnetic field formed by the magnet, the magnetorheological polishing liquid on the upper end of the polishing disk 7 forms a magnetorheological polishing pad 8 with viscoelasticity. The workpiece is in dynamic pressure contact with the magnetorheological polishing pad 8 in the lower recessed area to polish and grind the bottom surface of the workpiece.

[0062] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0063] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A jet hydrodynamic magnetorheological polishing device, comprising a base (2), a workpiece dynamic structure being arranged on the base (2), and a magnet capable of covering a processing surface being arranged below the workpiece dynamic structure; The workpiece dynamic structure comprises a dynamic pressure top cover (11) and a workpiece public rotation mechanism, wherein the workpiece public rotation mechanism is used to rotate the dynamic pressure top cover (11), and is characterized in that: The dynamic pressure top cover (11) is provided with a recessed portion at the installation position of the workpiece; The invention also comprises a polishing disc (7), a polishing liquid inlet (36) and a polishing liquid outlet (9); the top of the polishing disc (7) is sealed and connected to the dynamic pressure top cover (11) to form a cavity; the processing surface of the workpiece to be polished abuts against the cavity; the polishing liquid inlet (36) is arranged at the geometric center position of the bottom of the polishing disc (7) and is connected to the cavity; the polishing liquid outlet (9) is arranged on the side wall of the polishing disc (7) and is connected to the cavity; the polishing liquid inlet (36) is provided with a peristaltic pump for inputting the polishing liquid; a magnet is arranged on the other side of the cavity relative to the workpiece to be polished; the polishing liquid forms a magnetorheological polishing pad (8) at the position of the workpiece to be polished under the magnetorheological effect of the magnet.

2. The jet hydrodynamic magnetorheological polishing device according to claim 1 is characterized in that: One or more recessed portions are provided on the dynamic pressure top cover (11); when the number of the recessed portions is greater than one, the recessed portions are rotationally symmetrically arranged along the geometric center of the dynamic pressure top cover (11).

3. The jet fluid pressure magnetorheological polishing device according to claim 1 or 2, characterized in that: It also includes a magnetic field power structure, wherein the magnet is arranged on the top surface of the magnetic field power structure, and the magnetic field power structure includes a magnet rotating shaft (38) and a first motor (25) fixed on the base (2), and the output shaft of the first motor (25) is connected to the magnet rotating shaft (38) through a transmission part, thereby driving the magnet rotating shaft (38) to rotate.

4. The jet hydrodynamic magnetorheological polishing device according to claim 3 is characterized in that: A gap is left between the top of the magnet rotating shaft (38) and the bottom surface of the polishing plate (7), one or more magnets are arranged on the top of the magnet rotating shaft (38), and the distance between the magnet and the bottom surface of the polishing plate (7) is any value between 0.5 mm and 5 mm. The magnet is an annular permanent magnet, and the magnetic field strength of the annular permanent magnet is any value between 2000 Gs and 6000 Gs.

5. The jet fluid pressure magnetorheological polishing device according to claim 1 or 4, characterized in that: The workpiece rotating mechanism comprises a second motor (44) and a rotating spindle (17); one end of the rotating spindle (17) is connected to the output shaft of the second motor (44), and the other end is connected to the geometric center position of the dynamic pressure top cover (11).

6. The jet hydrodynamic magnetorheological polishing device according to claim 5, characterized in that: The dynamic pressure cover (11) is connected to the bottom of the rotating main shaft (17) via a first fastening screw (18) and can rotate relative to the polishing disc (7) at a speed of 10-100 r / min. A second sealing ring (23) is provided between the top of the polishing disc (7) and the dynamic pressure cover (11).

7. The jet fluid pressure magnetorheological polishing device according to claim 1 or 6, characterized in that: The workpiece power structure also includes a workpiece self-rotation mechanism, which includes a third motor (16), a third motor disk, a convex bottom plate (14) and a workpiece disk (13); the convex bottom plate (14) is arranged on the lower recess and has a through hole in the middle; the third motor (16) is mounted on the convex bottom plate (14); a third motor shaft (15) of the third motor (16) passes through the convex bottom plate (14) and is connected to the workpiece disk (13); and the workpiece disk (13) is sealed to the dynamic pressure top cover (11) via a first sealing ring (22).

8. The jet fluid pressure magnetorheological polishing device according to claim 7 is characterized in that: It also comprises a bottom plate (1), a base (2) fixedly connected to the bottom plate (1), and a bow-shaped bracket (41) fixedly connected to the bottom plate (1).

9. The jet hydrodynamic magnetorheological polishing device according to claim 8, characterized in that: The workpiece power structure also includes a linear displacement mechanism, which is fixed on the bow-shaped bracket (41). The linear displacement mechanism includes a guide rail panel (42) and a fourth motor (45). A vertical travel guide rail (43) is provided on the surface of the guide rail panel (42). The workpiece rotary mechanism is slidably connected to the travel guide rail (43) and is connected to the output shaft of the fourth motor (45), and can move up and down along the travel guide rail (43).

10. A jet hydrodynamic magnetorheological polishing method, using the jet hydrodynamic magnetorheological polishing device according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1, according to the characteristics of the workpiece to be processed, select a magnet with a suitable magnetic field strength, and install it on the lower part of the workpiece power structure in a manner of adjacent same magnetic poles or adjacent different magnetic poles, and at the same time, install the polishing disc (7) on the base (2); Step S2, clamping the workpiece on the lower concave portion of the dynamic pressure top cover (11) by vacuum adsorption or waxing, so that the processing surface of the workpiece is located within the range of the processing surface of the polishing device; Step S3, installing a sealing structure between the dynamic pressure cover (11) and the polishing plate (7), and adjusting the dynamic pressure cover (11) until the bottom surface of the lower concave portion of the dynamic pressure cover (11) is 1-5 mm away from the polishing plate (7); Step S4, adding 1%-10% micron-sized abrasive, 15%-60% micron-sized carbonyl iron powder, 2%-10% dispersant, and 1%-10% stabilizer to deionized water, stirring for 5-20 minutes with a magnetic stirrer, and then vibrating by ultrasonic waves for 5-20 minutes to form a magnetorheological polishing liquid; Step S5, injecting the magnetorheological polishing liquid prepared in step S4 from the polishing liquid inlet (36) through a peristaltic pump, and the polishing liquid flows out from the polishing liquid outlet (9), and the polishing liquid forms a magnetorheological polishing pad (8) under the magnetorheological effect of the magnet; Step S6, starting the workpiece rotary mechanism to drive the dynamic pressure top cover (11) to rotate at a speed of 10-100 r / min, the magnetorheological polishing fluid on the upper end of the polishing disc (7) forms a magnetorheological polishing pad (8) with viscoelasticity under the excitation of the composite magnetic field formed by the magnet, and the workpiece and the magnetorheological polishing pad (8) are in dynamic pressure contact in the lower concave area, and magnetorheological polishing of the workpiece can be achieved through the relative movement between the workpiece and the magnetorheological polishing pad (8).

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