Dynamic pressure polishing device for regularly changing cluster magneto-rheological machining gaps

Abstract

The utility model discloses a dynamic pressure polishing device with regularly-changed cluster magneto-rheological machining gaps. The dynamic pressure polishing device comprises a support base structure, a polishing disc structure and a variable-gap workpiece power structure. The variable-gap workpiece power structure comprises a linear displacement structure, a rotating structure and a cam movement structure. And the regular change of the machining gap is completed by a cam movement structure. According to the dynamic pressure polishing device with the regularly-changed cluster magneto-rheological machining gaps, the technical problem that the polishing pressure is lost due to the fact that deformation of the magneto-rheological polishing pad cannot be recovered under the fixed gap polishing effect is solved, and circulating updating of grinding materials can be achieved in the regularly-changed machining gap process; and the polishing force and the polishing effect of the workpiece are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of polishing, in particular to a hydrodynamic polishing device with regularly changing gaps in cluster magnetorheological machining. Background Art

[0002] With the vigorous development of optoelectronic information technology, the requirements for the planarization technology of integrated circuits in various fields are also constantly increasing. To ensure the quality requirements of lithography, the surface flatness and surface roughness of wafers reach the nanometer level or even the atomic level, and at the same time, there are almost stringent requirements for surface defects, cleanliness, and strength. This makes the ultra-smooth surface planarization processing of wafers a key issue in integrated circuit manufacturing.

[0003] Traditional semiconductor materials such as single crystal silicon, silicon carbide, gallium arsenide, sapphire, etc. generally need to go through processes such as crystal bar growth, slicing, chamfering, grinding, and polishing. To meet the usage requirements of industrial production, their surface accuracy needs to reach an ultra-smooth level (roughness Ra below 1 nm), and at the same time, there are also high requirements for surface shape accuracy (surface shape accuracy below 0.5 μm). Existing domestic and foreign processing devices for semiconductor wafers mainly include high-efficiency grinding, ultra-precision polishing, chemical mechanical polishing, etc. Cluster magnetorheological polishing, as a technology that can be used for the planarization processing of semiconductor substrate wafers, uses magnetorheological fluid to form a flexible polishing pad to perform material removal processing on the processing surface. However, the processing efficiency is relatively low. At the same time, most magnetorheological polishing processing devices use fixed processing gaps for polishing. This polishing process will cause the formed magnetorheological fluid polishing pad to be squeezed for a long time and damaged, weakening the self-trimming and abrasive renewal and self-sharpening functions of the polishing pad, reducing the polishing force, reducing the polishing quality, and making it difficult to maintain the processing stability of the workpiece, restricting the further development and application of this process. For example, the patent CN201410440862.6 provides a new magnetorheological polishing method and a polishing tool composed of three-layer concentric circular electromagnets. This patent determines the position of the wafer polishing tool and the polishing gap, and establishes a polishing force distribution model for material removal, which can achieve an ideal polishing effect. However, this patent works under a fixed polishing gap, does not consider the polishing effect of dynamic processing gaps, and the extrusion wear of the polishing pad during the fixed-gap polishing process will affect the polishing force. At the same time, due to the long-term extrusion wear of the polishing pad, it is difficult to control the uniformity of the distribution of the flexible small grinding heads formed during the polishing process, which will reduce the processing effect.

[0004] At present, a large number of studies have shown that: if the processing gap is too wide, the contact between the workpiece and the polishing pad is insufficient, the polishing force is tiny, the material removal rate of the workpiece surface is low, and the polishing effect is poor; if the processing gap is too narrow, the workpiece and the polishing pad are overly squeezed, the polishing force increases sharply, resulting in scratches on the workpiece surface by large abrasive particles, affecting the polishing quality; an appropriate processing gap can solve the problem of material removal processing of the polishing pad on the workpiece surface, but due to the long-term extrusion of the workpiece on the polishing pad, the polishing pad is worn, and in a static magnetic field, the polishing pad lacks the functions of self-trimming and abrasive self-sharpening, and the polishing force is unstable.

[0005] Therefore, how to provide a hydrodynamic polishing device with a regularly changing cluster magnetorheological processing gap to improve the processing quality and efficiency of the workpiece surface is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0006] The utility model proposes a hydrodynamic polishing device with a regularly changing cluster magnetorheological processing gap to effectively improve the polishing force and polishing quality in order to solve the above technical problems.

[0007] In order to achieve the above object, the utility model adopts the following technical scheme:

[0008] A hydrodynamic polishing device with a regularly changing cluster magnetorheological processing gap, including a support base structure, a polishing disc structure, and a variable-gap workpiece power structure. The polishing disc structure is arranged at the lower end of the support base structure, and the variable-gap workpiece power structure is arranged at the upper end of the support base structure;

[0009] The support base structure includes a bottom plate, a convex bottom plate, and an arched support. The convex bottom plate is fixed at the upper end of the bottom plate, and the arched support is fixed on one side of the bottom plate;

[0010] The polishing disc structure includes a first servo motor, a driving pulley, a driven pulley, a synchronous belt, a main shaft, and bearings. The main shaft is arranged in the polishing device base through the bearings. The first servo motor is fixed at the upper end of the convex bottom plate. The driving pulley is connected to the main shaft of the first servo motor. The driven pulley is arranged at the lower end of the main shaft. The driven pulley is connected to the driving pulley through the synchronous belt. The polishing device base is a hollow structure and is fixed at the upper end of the convex bottom plate. The end cover of the bearing is fixed at the upper port of the polishing device base. The polishing disc is fixed at the upper end of the main shaft, and a partition plate is arranged in the polishing disc;

[0011] The variable-gap workpiece power structure includes a linear displacement structure, a rotary structure, and a cam motion structure. The linear displacement structure is arranged at the upper end of the arched support. The rotary structure is arranged at the upper end of the linear displacement structure. A workpiece disc is connected to the lower end of the rotary structure. The cam motion structure is fixed at the upper part of the rotary structure;

[0012] The linear displacement structure includes a stroke panel, a moving slider, and a stroke guide rail. The rotation structure includes a first motor fixing plate, a second servo motor, a workpiece disk connecting member, and a workpiece disk. The cam motion structure includes a cam, a third servo motor, an L-shaped motor fixing plate, and a baffle. The stroke panel is fixed on the bow-shaped bracket. A stroke guide rail is provided on the surface of the stroke panel. The first motor fixing plate is fixed on the moving slider. The moving slider is fixed on the stroke guide rail. The second servo motor is fixed at the upper end of the first motor fixing plate. The L-shaped motor fixing plate is arranged at the upper end of the stroke panel. The third servo motor is fixed at the lower end of the L-shaped motor fixing plate. The cam contacts the upper end surface of the baffle. The second servo motor is arranged at the lower end of the baffle. The workpiece disk connecting member is connected to the main shaft of the second servo motor. The workpiece disk is arranged at the lower end of the workpiece disk connecting member. The workpiece disk is provided with a plurality of workpiece clamping positions, and the workpieces are respectively installed on the workpiece clamping positions of the workpiece disk.

[0013] The polishing device base is fixed on the upper end of the convex plate. The upper port of the polishing device base is connected to the bearing end cover. The main shaft is arranged in the polishing device base through a first tapered roller bearing and a second tapered roller bearing. The lower end of the main shaft is connected to the driven pulley through a fastening screw. The driving pulley is connected to the main shaft of the first servo motor through a connecting key. The first tapered roller bearing and the second tapered roller bearing are sealed around.

[0014] Further, the motor speed of the third servo motor is 1 r / min ~ 1000 r / min.

[0015] Further, the difference range between the major axis and the minor axis of the contour curve of the cam is 0.2 mm to 2 mm.

[0016] Further, the major axis of the cam is an elliptical curve, and the minor axis of the cam is a circular curve.

[0017] Further, the cam motion structure further includes a spring reset mechanism. The spring reset mechanism includes a reset spring and a spring limit rod. The upper end of the spring limit rod is fixed on the lower end surface of the L-shaped motor fixing plate. The lower end of the spring limit rod is fitted with the baffle. The reset spring is arranged in the middle of the spring limit rod. The upper end of the reset spring is connected to the L-shaped motor fixing plate. The lower end of the reset spring is connected to the baffle. The reset spring and the cam act together on the upper end of the baffle to jointly drive the processing workpiece disk to vibrate up and down.

[0018] Furthermore, the upper end of the polishing disc is of a cup-shaped structure, the magnetorheological fluid is arranged inside the cup-shaped body, the bottom of the polishing disc has a cavity, and a cylindrical permanent magnet is arranged in the cavity; the cylindrical permanent magnet is axially magnetized, and two adjacent cylindrical permanent magnets are arranged in the same or opposite directions.

[0019] In summary, the beneficial effects of the present utility model are as follows:

[0020] For the hydrodynamic polishing device with regularly changing machining gap of the present utility model, (1) Under the action of the static magnetic field, since there is no relative movement between the polishing disc and the cylindrical permanent magnet, the magnetic field lines formed by the cylindrical permanent magnet do not change at the surface position of the polishing disc. During the polishing process with a fixed gap, there is no process of breakage and formation of the magnetic particle chain strings in the polishing pad, so that the polishing pad squeezed by the rotation of the workpiece cannot restore its morphology, and its polishing force cannot stably act on the surface of the workpiece; when the workpiece disc vibrates up and down relative to the polishing disc, the damaged magnetic particle chain strings in the polishing pad alternate during the process of restoration and breakage, which can force the magnetorheological fluid polishing pad without abrasive renewal to transform into a polishing pad with abrasive self-sharpening and real-time shape restoration, maintaining the stability of the polishing force during the material removal process and solving the core problem that the processing pressure on the workpiece is lost due to the deformation of the magnetorheological fluid under the viscous and magnetic effects during static magnetic field polishing. Changing the morphology of the cam and adjusting the motor speed can change the up-and-down vibration law of the workpiece disc. At the same time, the regular change of the machining gap will change the instantaneous velocity of the magnetorheological polishing fluid flowing through the machining gap, increasing the extrusion between the abrasives and generating a hydrodynamic pressure effect, which can promote the material removal of the abrasives on the surface of the workpiece and effectively improve the polishing force;

[0021] (2) The regular change of the machining gap can effectively fit the immersion effect of the magnetorheological fluid. The immersion effect means that when there are large and small abrasive grains during the machining process, the large abrasive grains are immersed in the flexible polishing pad formed by iron powder under the action of pressure, enabling the fine and large abrasive grains to contact the workpiece simultaneously and perform micron cutting on the workpiece, avoiding scratches on the workpiece by the coarse abrasive grains. When the workpiece disk moves upward, the machining gap widens, the extrusion effect between the workpiece and the polishing pad weakens, and the surface scratches of the material decrease. When the workpiece disk moves downward, the machining gap narrows. At this time, after the polishing pad is repaired, the fine abrasive grains adhere to the outermost layer. When the workpiece disk contacts the polishing pad, it is ensured that the fine abrasive grains contact the workpiece disk first, reducing the scratching of the material surface caused by the narrowing of the machining gap. Since the polishing of optoelectronic materials requires nanoscale and sub-nanoscale surface roughness, micron-scale surface shape accuracy, and no surface damage and stress, the immersion effect in magnetorheological polishing technology can process the wafer to a nanoscale ultra-smooth surface without causing surface damage. In addition, the magnetorheological fluid covers the surface of the polishing disk. During the polishing process, cluster micro-abrasive heads are used for polishing instead of traditional single-point polishing, and the workpieces are processed not individually but one or more at the same time, greatly improving the uniformity and efficiency of the polishing process, achieving the purpose of rapid polishing and enhancing the polishing effect. Importantly, the present utility model realizes a polishing method with a new regular change in the machining gap, ensuring the real-time restoration of the self-sharpening and shape of the magnetorheological fluid polishing pad into a pad with abrasives, effectively improving the polishing force of the polishing pad, ensuring the machining quality, and the device has a simple structure, only requiring an additional servo motor to drive the machining workpiece disk to move up and down according to a certain rule. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a front view structural schematic diagram of a hydrodynamic polishing device with a regular change in the machining gap of a cluster magnetorheological machining according to the present utility model;

[0023] Figure 2 is Figure 1 a front view sectional structural schematic diagram of a hydrodynamic polishing device with a regular change in the machining gap of a cluster magnetorheological machining as shown;

[0024] Figure 3 is Figure 1 a left view structural schematic diagram of a hydrodynamic polishing device with a regular change in the machining gap of a cluster magnetorheological machining as shown;

[0025] Figure 4 is Figure 1 a front view of the variable-gap workpiece power structure of a hydrodynamic polishing device with a regular change in the machining gap of a cluster magnetorheological machining as shown;

[0026] Figure 5 is Figure 1Left view of the variable-gap workpiece dynamic structure of a hydrodynamic polishing device with regularly changing cluster magnetorheological machining gaps as shown;

[0027] Figure 6 For Figure 1 Schematic diagram of the polishing process of a hydrodynamic polishing device with regularly changing cluster magnetorheological machining gaps as shown;

[0028] Figure 7 Schematic diagram of a cam structure in the form of triangular vibration;

[0029] Figure 8 Schematic diagram of a cam structure in the form of simple harmonic motion;

[0030] Figure 9 Schematic diagram of a cam structure in the form of quick return motion;

[0031] In the figure: 1 - base plate, 2 - convex base plate, 3 - first fastening screw, 4 - driving pulley, 5 - second fastening screw, 6 - first servo motor, 7 - polishing device base, 8 - first tapered roller bearing, 9 - third fastening screw, 10 - main shaft, 11 - polishing disc, 12 - cylindrical permanent magnet, 13 - partition plate, 14 - magnetorheological polishing pad, 15 - magnetorheological fluid, 16 - stroke panel, 17 - moving slider, 18 - fourth fastening screw, 19 - first motor fixing plate, 20 - second servo motor, 21 - fifth fastening screw, 22 - workpiece disc connecting piece, 23 - bow-shaped bracket, 24 - workpiece disc, 25 - workpiece, 26 - sixth fastening screw, 27 - bearing end cover, 28 - inner sleeve, 29 - outer sleeve, 30 - second tapered roller bearing, 31 - seventh fastening screw, 32 - stroke guide rail, 33 - return spring, 34 - cam, 35 - L-shaped motor fixing plate, 36 - third servo motor, 37 - coupling key, 38 - synchronous belt, 39 - eighth fastening screw, 40 - driven pulley, 41 - baffle, 42 - spring limit rod. Detailed implementation manners

[0032] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0033] Please refer to Figures 1-6, the present utility model provides a hydrodynamic polishing device with regularly changing machining gaps in cluster magnetorheological machining, including a support base structure, a polishing disc power structure, a polishing disc housing structure, and a variable-gap workpiece power structure. The variable-gap workpiece power structure is arranged at the upper end of the support base structure, and the polishing disc power structure is arranged at the lower end of the support base structure;

[0034] The support base structure includes a bottom plate (1), a convex bottom plate (2), and an arcuate support (23). The convex bottom plate (2) is arranged at the upper end of the bottom plate (1), and the arcuate support (23) is arranged above the bottom plate (1). Specifically, the convex bottom plate (2) is a hollow structure and is fixed to the upper end of the bottom plate (1) by a first fastening screw (3).

[0035] The polishing disc power structure includes a driving pulley (4), a first servo motor (6), a main shaft (10), a synchronous belt (38), a driven pulley (40), a first tapered roller bearing (8), and a second tapered roller bearing (30). The first servo motor (6) is fixed to the convex bottom plate (2) by a second fastening screw (5); the driving pulley (4) is connected to the main shaft of the first servo motor (6) through a coupling key (37); an outer sleeve (29) is sleeved on the main shaft (10), and an inner sleeve (28) is arranged inside the outer sleeve (29). The driven pulley (40) is fixed to the lower end face of the main shaft (10) by an eighth fastening screw (39); the driven pulley (40) is connected to the driving pulley (4) through a synchronous belt (38); the main shaft (10) is fixed inside the polishing device base (7) through the first tapered roller bearing (8) and the second tapered roller bearing (30);

[0036] The polishing disc housing structure includes a polishing device base (7), a polishing disc (11), a cylindrical permanent magnet (12), a partition plate (13), and a bearing end cover (27). The polishing device base (7) is a hollow structure and is fixed to the upper end face of the convex bottom plate (2) by a seventh fastening screw (31); the bearing end cover (27) is fixed at the upper stop of the polishing device base (7) by a third fastening screw (9) to limit the axial movement of the first tapered roller bearing (8); the polishing disc (11) is fixed to the upper end of the polishing device base (7) by a sixth fastening screw (26); a cavity is formed inside the polishing disc (11); the plurality of cylindrical permanent magnets (12) are arranged in the cavity of the polishing disc (11) through spacers; the upper part of the polishing disc (11) is cup-shaped for containing magnetorheological polishing fluid (15); the partition plate (13) is laid flat on the polishing disc (11).

[0037] In this embodiment, the variable-gap workpiece power structure includes a linear displacement structure, a rotating structure, and a cam motion structure. The linear displacement structure is fixed on the bow-shaped bracket (23); the rotating structure is arranged on the linear displacement structure; the cam mechanism is arranged on the rotating structure, and the lower end of the rotating structure is connected to the workpiece (25).

[0038] Among them, the linear displacement structure includes a travel panel (16), a moving slider (17), and a travel guide rail (32); the rotating structure includes a first motor fixing plate (19), a second servo motor (20), a workpiece disk connecting member (22), and a workpiece disk (24); the cam motion structure includes: a cam (34), a third servo motor (36), an L-shaped motor fixing plate (35), a return spring (33), a spring limiting rod (42), and a baffle (41); the travel panel (16) is fixed on the bow-shaped bracket (23) by a fourth fastening screw (18); the travel guide rail (32) is on the surface of the travel panel (16); the first motor fixing plate (19) is fixed on the moving slider (17) by a fifth fastening screw (21); the moving slider (17) is arranged on the travel guide rail (32); the second servo motor (20) is arranged at the upper end of the first motor fixing plate (19); the L-shaped motor fixing plate (35) is fixed at the upper end of the travel panel (16); the third servo motor (36) is arranged at the lower end of the L-shaped motor fixing plate (35); the cam (34) is arranged between the L-shaped motor fixing plate and the second servo motor (20); the spring limiting rod (42) is arranged between the L-shaped motor fixing plate (35) and the baffle (41), the upper end of the spring limiting rod (42) is fixed on the lower end surface of the L-shaped motor fixing plate (35), the lower end of the spring fixing rod (42) is not fixed and is connected to the baffle (41) by an embedding method, and the baffle (41) can move up and down in the spring limiting rod; the return spring (33) is arranged in the middle of the spring limiting rod (42), the upper end is connected to the L-shaped motor fixing plate (35), and the lower end is connected to the baffle (41); the baffle (41) is connected to the upper end of the second servo motor (20) by a fastening screw; the workpiece disk connecting member (22) is arranged on the main shaft of the second servo motor (20), and the workpiece disk (24) is fixed on the lower end surface of the workpiece disk connecting member (22) by a fastening screw; the workpiece disk (24) is provided with a plurality of workpiece clamping positions; the workpieces (25) are respectively installed on the workpiece clamping positions of the workpiece disk (24).

[0039] Among them, the workpiece (25) is clamped on the workpiece disk (24) by means of vacuum adsorption or wax pasting, etc., and the workpiece (25) is located within the polishing range of the polishing device. The second servo motor (20) is started to realize the high-speed rotation of the workpiece disk (24) driving the workpiece (25). The third servo motor (36) is started, and the movement of the cam (34) is used to realize the reciprocating up and down movement of the moving slider (17) driving the workpiece (25). The first servo motor (6) is started, and the first servo motor (6) drives the driving pulley (4) to rotate at a high speed. The driven pulley (40) drives the main shaft (10) to rotate at a high speed under the drive of the synchronous belt (38). Therefore, the main shaft (10) can drive the polishing disk (11) to rotate at a high speed relative to the workpiece. The polishing liquid (15) at the upper end of the polishing disk (11) forms a magnetorheological polishing pad (14) with viscoelasticity under the excitation of the magnetic field formed by the cylindrical permanent magnet (12). Through the relative movement between the workpiece (25) and the magnetorheological polishing pad (14), the high-efficiency, ultra-smooth and non-damaging magnetorheological polishing removal of the workpiece (25) can be realized.

[0040] A counterbore is provided at the upper end of the polishing disk (11), and one or more cylindrical permanent magnets (12) are arranged in the counterbore. During specific assembly, the distance between the upper part of the cylindrical permanent magnet (12) and the outer ring of the partition plate (13) is any value between 0.5 mm and 5 mm. Among them, the cylindrical permanent magnet (12) is preferably a permanent magnet (12) with a magnetic field strength of 2000 Gs to 6000 Gs.

[0041] The regular change of the above machining gap can be adjusted by replacing cams (34) with different morphologies and the rotation speed of the third servo motor (36). The rotation speed of the motor (36) directly determines the vibration frequency; the morphology of the cam (34) determines the vibration mode and amplitude of the machining gap.

[0042] Please refer to Figure 7 , the dynamic pressure polishing method for triangular vibration of a cluster magnetorheological machining gap includes the following steps:

[0043] 1) According to the structure of the machine tool, design a suitable structure of a dynamic pressure polishing device for triangular vibration of a cluster magnetorheological machining gap:

[0044] 2) According to the characteristics of the single-crystalline silicon substrate, select cylindrical permanent magnets with appropriate magnetic field strength, and install them inside the polishing disk of a polishing device with regularly changing machining gaps in the adjacent like-pole or adjacent unlike-pole manner. The polishing disk is fixed on the main shaft through connecting threads. The main shaft is fixed inside the polishing device through tapered roller bearings. The upper end of the main shaft is pre-tightened by a bearing end cover, and the lower end of the main shaft is connected to the main shaft of the first servo motor through a synchronous belt;

[0045] 3) Clamp the workpiece at the clamping position of the workpiece disk by means of vacuum adsorption or wax pasting, etc., and within the corresponding range polished by the polishing device;

[0046] 4) Add abrasive of micron level with a concentration of 4% in deionized water, add micron-level carbonyl iron powder with a concentration of 10% in deionized water, add a dispersant with a concentration of 5%, and a stabilizer with a concentration of 2% - 10%. Stir with a magnetic stirrer for 5 minutes and then vibrate ultrasonically for 20 minutes to form a magnetorheological fluid;

[0047] 5) Add the magnetorheological fluid into the cup-shaped structure above the polishing disk through a nozzle. The magnetorheological fluid forms a magnetorheological polishing pad under the magnetorheological effect of the cylindrical permanent magnet;

[0048] 6) Start the second servo motor to make the processing workpiece disk rotate self - rotatably. Adjust the up - down position of the moving slider and the length of the return spring to ensure that the initial processing gap between the processing workpiece disk and the polishing disk is 1 mm. Start the first servo motor, and the motor spindle drives the main shaft to revolve at a speed of 700 rpm through a synchronous belt. Start the third servo motor, and the motor spindle drives the cam to rotate at a speed of 50 rmp. Under the combined action of the cam and the return spring, the processing workpiece disk vibrates up and down relative to the polishing disk according to a certain law. The vibration law can be achieved by changing the motor speed and the cam profile. Therefore, the above structure can realize the stable revolution of the polishing disk, and the processing workpiece disk rotates self - rotatably while vibrating up and down regularly. The revolution of the polishing disk, the self - rotation of the processing workpiece disk, and the up - down vibration of the three jointly realize the material removal of the workpiece by the magnetorheological polishing pad;

[0049] 7) Obtain the specific value of the material removal rate according to the theoretical modeling analysis of the removal rate and the measurement and calculation of actual experiments. Then determine the feed amount in the Z - direction of the linear displacement structure in the processing state according to the size of the material removal rate, so as to ensure that the change law of the processing gap between the polishing disk and the workpiece surface remains stable and realize the stable polishing of the magnetorheological polishing pad; or install a detector on the polishing device. In the polishing processing state, the needle of the detector periodically detects the processing gap between the polishing disk and the workpiece. The detected data is processed through the feedback of the numerical control system, and the feed amount in the Z - direction of the linear displacement structure is adjusted according to the change of the processing gap, so as to ensure that the change law of the processing gap between the polishing disk and the workpiece surface remains stable, and realize the polishing and removal of the workpiece surface material under the stable shearing action of the magnetorheological polishing pad and the rotation of the workpiece itself, and obtain a smooth workpiece surface without subsurface damage;

[0050] Please refer to Figure 8 It can be understood that in another embodiment, the present invention also provides a hydrodynamic polishing method for the simple harmonic vibration of the cluster magnetorheological processing gap, including the following steps:

[0051] 1) According to the structure of the machine tool, design a structure of a hydrodynamic polishing device with a simple harmonic vibration of the cluster magnetorheological machining gap that is adapted:

[0052] 2) According to the characteristics of the silicon carbide substrate, select cylindrical permanent magnets with appropriate magnetic field intensities and install them inside the polishing disc of a polishing device with regularly changing machining gaps in the way of adjacent like magnetic poles or adjacent unlike magnetic poles. Fix the polishing disc on the main shaft through connecting threads. The main shaft is fixed inside the polishing device through tapered roller bearings. The upper end of the main shaft is pre-tightened by a bearing end cover, and the lower end of the main shaft is connected to the main shaft of the first servo motor through a synchronous belt;

[0053] 3) Clamp the workpiece on the clamping position of the workpiece disc by means of vacuum adsorption or wax sticking, etc., and within the corresponding range polished by the polishing device;

[0054] 4) Add abrasive with a concentration of 4% in deionized water, micron-sized carbonyl iron powder with a concentration of 35% in deionized water, a dispersant with a concentration of 10%, and a stabilizer with a concentration of 5%. Stir with a magnetic stirrer for 5 minutes and then vibrate ultrasonically for 20 minutes to form a magnetorheological fluid;

[0055] 5) Add the magnetorheological fluid into the cup-shaped structure above the polishing disc through a nozzle. The magnetorheological fluid forms a magnetorheological polishing pad under the magnetorheological effect of the cylindrical permanent magnet;

[0056] 6) Start the second servo motor to make the machining workpiece disc rotate. Adjust the up and down position of the moving slider and the length of the return spring to ensure that the initial machining gap between the machining workpiece disc and the polishing disc is 0.8 mm. Start the first servo motor. The main shaft of the motor drives the main shaft to revolve at a speed of 700 rpm through a synchronous belt. Start the third servo motor. The main shaft of the motor drives the cam to rotate at a speed of 60 rmp. Under the combined action of the cam and the return spring, the machining workpiece disc vibrates up and down relative to the polishing disc according to a certain law. The vibration law can be achieved by changing the motor speed and the cam profile. Therefore, the above structure can realize the stable revolution of the polishing disc, and the machining workpiece disc rotates while vibrating up and down according to a certain law. The revolution of the polishing disc, the rotation of the machining workpiece disc, and the up and down vibration of the three motions together achieve the material removal of the workpiece by the magnetorheological polishing pad;

[0057] 7) Based on the theoretical modeling analysis of the removal rate and the measurement and calculation of actual experiments, the specific value of the material removal rate is obtained, and then the feed amount in the Z direction of the linear displacement structure in the processing state is determined according to the size of the material removal rate, so as to ensure that the variation law of the machining gap from the polishing pad to the workpiece surface remains stable, realizing stable polishing of the magnetorheological polishing pad; or a detector is installed on the polishing device. In the polishing processing state, the needle of the detector periodically detects the machining gap between the polishing pad and the workpiece. The detected data is processed through the feedback of the numerical control system, and the feed amount in the Z direction of the linear displacement structure is adjusted according to the change of the machining gap, so as to ensure that the variation law of the machining gap from the polishing pad to the workpiece surface remains stable, and realizing the polishing and removal of the workpiece surface material under the stable shearing action of the magnetorheological polishing pad and the rotation of the workpiece itself, obtaining a smooth workpiece surface without subsurface damage;

[0058] Please refer to Figure 9 , the present utility model also provides a hydrodynamic polishing method for the rapid return vibration of the machining gap in cluster magnetorheological processing, including the following steps:

[0059] 1) According to the structure of the machine tool, design a suitable hydrodynamic polishing device structure for the rapid return vibration of the machining gap in cluster magnetorheological processing:

[0060] 2) According to the characteristics of K9 glass, select cylindrical permanent magnets with appropriate magnetic field intensity, and install them inside the polishing pad of a polishing device with regularly changing machining gaps in the way of adjacent like poles or adjacent unlike poles. The polishing pad is fixed on the main shaft through connecting threads. The main shaft is fixed inside the polishing device through tapered roller bearings. The upper end of the main shaft is pre-tightened by a bearing end cover, and the lower end of the main shaft is connected to the main shaft of the first servo motor through a synchronous belt;

[0061] 3) Clamp the workpiece on the clamping position of the workpiece disk by means of vacuum adsorption or wax sticking, etc., and within the corresponding range polished by the polishing device;

[0062] 4) Add abrasive with a concentration of 4% in micron size in deionized water, and add carbonyl iron powder with a concentration of 35% in micron size in deionized water, and add a dispersant with a concentration of 5% and a stabilizer with a concentration of 5%. Stir with a magnetic stirrer for 5 minutes and then vibrate with ultrasonic waves for 20 minutes to form a magnetorheological fluid;

[0063] 5) Add the magnetorheological fluid into the cup-shaped structure above the polishing pad through the nozzle. The magnetorheological fluid forms a magnetorheological polishing pad under the magnetorheological effect of the cylindrical permanent magnet;

[0064] 6) Start the second servo motor to make the workpiece disk rotate self - rotatably, adjust the vertical position of the moving slider and the length of the return spring to ensure that the initial machining gap between the workpiece disk and the polishing disk is 0.8 mm; start the first servo motor, the motor spindle drives the main shaft to revolve at a speed of 700 rpm through the synchronous belt, start the third servo motor, the motor spindle drives the cam to rotate at a speed of 50 rmp. Under the combined action of the cam and the return spring, the workpiece disk vibrates up and down relative to the polishing disk according to a certain law, and the vibration law can be achieved by changing the motor speed and the cam profile; so the above - mentioned structure can realize the stable revolution of the polishing disk, and the workpiece disk vibrates up and down regularly while rotating self - rotatably; the revolution of the polishing disk, the self - rotation of the workpiece disk and the up - and - down vibration of the three movements together realize the material removal of the workpiece by the magnetorheological polishing pad;

[0065] 7) According to the theoretical modeling analysis of the material removal rate and the measurement and calculation of the actual experiment, obtain the specific value of the material removal rate, and then determine the feed amount in the Z - direction of the linear displacement structure in the machining state according to the size of the material removal rate, so as to ensure that the change law of the machining gap between the polishing disk and the workpiece surface remains stable and realize the stable polishing of the magnetorheological polishing pad; or install a detector on the polishing device. In the polishing machining state, the needle of the detector regularly detects the machining gap between the polishing disk and the workpiece. The detected data is processed through the feedback of the numerical control system, and the feed amount in the Z - direction of the linear displacement structure is adjusted according to the change of the machining gap, so as to ensure that the change law of the machining gap between the polishing disk and the workpiece surface remains stable, and realize the polishing and removal of the workpiece surface material under the stable shearing action of the magnetorheological polishing pad and the rotation of the workpiece itself, and obtain a smooth workpiece surface without subsurface damage;

[0066] In summary, the present utility model provides a hydrodynamic polishing device with a regularly changing machining gap for cluster magnetorheological machining. This device can force the workpiece disk to vibrate up and down regularly, making the micron - level iron powder chain strings under the magnetic field continuously break and form. Under the action of the magnetic field, it can force the magnetorheological fluid polishing pad without abrasive renewal to transform into a polishing pad with self - sharpening and real - time shape recovery of the abrasive, solving the core problem that under the action of static magnetic field polishing, due to the viscosity and magnetic action of the magnetorheological fluid, the deformation cannot be restored and the machining pressure on the workpiece is lost. At the same time, the regular change of the machining gap forces the flow rate of the magnetorheological fluid flowing through the machining gap to change, the pressure of the magnetorheological fluid polishing pad on the workpiece changes, generating a hydrodynamic pressure effect, which can increase the extrusion effect of the abrasive in the magnetorheological fluid on the workpiece, effectively improve the polishing force and the polishing effect.

[0067] In addition, the present utility model provides a hydrodynamic polishing method with regularly changing gaps in cluster magnetorheological machining, which can effectively fit the powder-holding effect in magnetorheological polishing. The powder-holding effect occurs when there are large and small abrasive grains during the machining process. Under the action of pressure, the large abrasive grains are held in the flexible polishing pad formed by iron powder, enabling the fine and large abrasive grains to contact the workpiece simultaneously and perform micron-scale cutting on the workpiece, thus avoiding scratches on the workpiece caused by the coarse abrasive grains. The reciprocating movement of the workpiece up and down can also reduce the scratches on the workpiece surface caused by the large abrasive grains. Since the processing of optoelectronic materials requires nanoscale and sub-nanoscale surface roughness, micron-scale surface shape accuracy, and no surface damage and stress, the powder-holding effect in cluster magnetorheological polishing technology and the regularly changing machining gaps designed in this device can process the optoelectronic materials to obtain a nanoscale ultra-smooth surface without surface damage. In addition, the magnetorheological fluid covers the surface of the polishing disc. During the polishing process, the contact form between the polishing pad and the workpiece is line contact, replacing the traditional point contact. Under the excitation of multiple cylindrical permanent magnets, cluster micro-abrasive heads are formed on the surface of the polishing disc. The contact area between the workpiece and the polishing pad is greatly increased, and the workpiece is processed not individually but one or more at the same time, greatly improving the uniformity and efficiency of the polishing process and achieving the purpose of rapid polishing and enhanced polishing effect. Importantly, the present utility model realizes a polishing method with regularly changing gaps in cluster magnetorheological machining, which can solve the problem of the decline in polishing effect caused by the long-term extrusion and damage of the polishing pad, effectively improve the polishing force, and enhance the polishing effect. Using the hydrodynamic polishing device with regularly changing gaps in cluster magnetorheological machining provided by the present utility model can obtain high-quality workpieces with good surface consistency and no surface and subsurface damage, and it has a low cost, making it very suitable for the high-efficiency ultra-smooth and uniform polishing of optical components.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and not to limit the protection scope of the present utility model. Although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present utility model can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present utility model.

Claims

1. A hydrodynamic polishing device with regularly changing gaps in cluster magnetorheological machining, characterized in that It includes a bracket base structure, a polishing disc structure, and a variable-gap workpiece power structure. The polishing disc structure is arranged at the lower end of the bracket base structure, and the variable-gap workpiece power structure is arranged at the upper end of the bracket base structure. The bracket base structure includes a bottom plate, a convex bottom plate, and an arched bracket. The convex bottom plate is fixed to the upper end of the bottom plate, and the arched bracket is fixed to one side of the bottom plate. The polishing disc structure includes a first servo motor, a driving pulley, a driven pulley, a synchronous belt, a main shaft, and a bearing. The main shaft is arranged in the polishing device base through the bearing. The first servo motor is fixed to the upper end of the convex bottom plate. The driving pulley is connected to the main shaft of the first servo motor. The driven pulley is arranged at the lower end of the main shaft. The driven pulley is connected to the driving pulley through the synchronous belt. The polishing device base is a hollow structure and is fixed to the upper end of the convex bottom plate. The end cover of the bearing is fixed to the upper port of the polishing device base. The polishing disc is fixed to the upper end of the main shaft, and a partition plate is arranged in the polishing disc. The variable-gap workpiece power structure includes a linear displacement structure, a rotating structure, and a cam motion structure. The linear displacement structure is arranged at the upper end of the arched bracket. The rotating structure is arranged at the upper end of the linear displacement structure. A workpiece disc is connected to the lower end of the rotating structure. The cam motion structure is fixed to the upper part of the rotating structure. The linear displacement structure includes a stroke panel, a moving slider, and a stroke guide rail. The rotating structure includes a first motor fixing plate, a second servo motor, a workpiece disc connecting piece, and a workpiece disc. The cam motion structure includes a cam, a third servo motor, an L-shaped motor fixing plate, and a baffle. The stroke panel is fixed to the arched bracket. The surface of the stroke panel is provided with a stroke guide rail. The first motor fixing plate is fixed to the moving slider. The moving slider is fixed to the stroke guide rail. The second servo motor is fixed to the upper end of the first motor fixing plate. The L-shaped motor fixing plate is arranged at the upper end of the stroke panel. The third servo motor is fixed to the lower end of the L-shaped motor fixing plate. The cam is in contact with the upper end surface of the baffle. The second servo motor is arranged at the lower end of the baffle. The workpiece disc connecting piece is connected to the main shaft of the second servo motor. The workpiece disc is arranged at the lower end of the workpiece disc connecting piece. The workpiece disc is provided with a plurality of workpiece clamping positions, and the workpieces are respectively installed in the workpiece clamping positions of the workpiece disc. The polishing device base is fixed to the upper end of the convex plate. The upper port of the polishing device base is connected to the bearing end cover. The main shaft is arranged in the polishing device base through a first tapered roller bearing and a second tapered roller bearing. The lower end of the main shaft is connected to the driven pulley through a fastening screw. The driving pulley is connected to the main shaft of the first servo motor through a connection key. The first tapered roller bearing and the second tapered roller bearing are sealed around.

2. The hydrodynamic polishing device with regularly changing machining gaps for cluster magnetorheological machining according to claim 1, characterized in that The motor speed of the third servo motor is 1 r / min ~ 1000 r / min.

3. The hydrodynamic polishing device with regularly changing machining gaps in cluster magnetorheological machining according to claim 1, characterized in that, The difference range between the major axis and the minor axis of the contour curve of the cam is 0.2 mm to 2 mm.

4. The hydrodynamic polishing device with regularly changing machining gaps in cluster magnetorheological machining according to claim 1, characterized in that, The major axis of the cam is an elliptical curve, and the minor axis of the cam is a circular curve.

5. The hydrodynamic polishing device with regularly changing cluster magnetorheological machining gap according to claim 1, characterized in that, The cam motion structure further includes a spring reset mechanism, which includes a reset spring and a spring limiting rod. The upper end of the spring limiting rod is fixed to the lower end surface of the L-shaped motor fixing plate, and the lower end of the spring limiting rod is fitted with a baffle. The reset spring is arranged in the middle of the spring limiting rod. The upper end of the reset spring is connected to the L-shaped motor fixing plate, and the lower end of the reset spring is connected to the baffle. The reset spring and the cam act together on the upper end of the baffle to jointly drive the processing workpiece disk to vibrate up and down.

6. The hydrodynamic polishing device with regularly changing machining gaps in cluster magnetorheological machining according to claim 1, characterized in that, The upper end of the polishing disc is a cup-shaped structure, and the magnetorheological fluid is arranged inside the cup-shaped body. The bottom of the polishing disc has a cavity, and a cylindrical permanent magnet is arranged in the cavity; the cylindrical permanent magnet is axially magnetized, and two adjacent cylindrical permanent magnets are arranged in the same or opposite directions.

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