A method for processing a sapphire crystal

Abstract

The application relates to the technical field of crystal processing, in particular to a sapphire crystal processing method, which comprises the following steps: clamping and fixing two ends of a sapphire crystal bar through a clamping mechanism, so that the sapphire crystal bar remains stationary; rotating a grinding wheel around its own axis and making the grinding wheel contact the side surface of the sapphire crystal bar for grinding; controlling the grinding wheel to move linearly along the length direction of the sapphire crystal bar, so as to perform axial linear pre-grinding on the side surface of the sapphire crystal bar; and the axial linear pre-grinding process is arranged before a sapphire crystal bar rounding processing process. Through the axial linear pre-grinding process before rounding, the technical effect of improving the rounding quality is achieved.

Description

Technical Field

[0001] This application relates to the field of crystal processing technology, and in particular to a method for processing sapphire crystals. Background Technology

[0002] Sapphire crystal possesses an ultra-high Mohs hardness of 9, excellent optical transmittance, strong chemical stability, and high temperature resistance, making it a core material for LED epitaxial substrates, third-generation semiconductor power device windows, high-end consumer electronics protective glass, and aerospace optical components.

[0003] In existing technologies, sapphire crystals need to be oriented and grown to obtain cylindrical crystal rods. Since the sapphire crystal rods obtained after rod cutting are not standard cylinders, they need to be rounded to precisely grind the blank crystal rods into standard cylinders, ensuring diameter tolerance, cylindricity, straightness, and surface roundness. However, due to the hard and brittle nature of sapphire crystal rods, problems such as microcracks and edge chipping are easily caused during the rounding process.

[0004] Therefore, the technical problem with the existing technology is that the sapphire crystal rods have low roundness quality. Summary of the Invention

[0005] This application provides a sapphire crystal processing method, which improves the rounding quality by setting a grinding wheel axial linear pre-grinding process before rounding.

[0006] This application provides a sapphire crystal processing method, which adopts the following technical solution: In summary, this application includes at least one of the following beneficial technical effects: This application adds a pre-grinding process of stationary crystal rod and axial straight grinding of the grinding wheel before the rounding process. This process pre-treats the polygonal facets and contour allowance of the crystal rod after rounding, significantly reducing the grinding allowance and processing difficulty of the subsequent rounding process, which is beneficial to improving the quality of the subsequent rounding process. Attached Figure Description

[0007] Figure 1 This is a first schematic diagram of the sapphire crystal rod processing apparatus described in this application; Figure 2 This is a schematic diagram of the first working state of the sapphire crystal rod processing apparatus described in this application; Figure 3 This is a schematic flowchart of the sapphire crystal rod processing method described in this application; Figure 4 This is a second schematic diagram of the sapphire crystal rod processing apparatus described in this application; Figure 5 This is a schematic diagram of the second working state of the sapphire crystal rod processing apparatus described in this application; Figure 6 This is a schematic diagram of the grinding wheel infeed end and the grinding wheel outlet end of the sapphire crystal rod processing apparatus described in this application; Figure 7 This is a flowchart illustrating the buffering action of the sapphire crystal rod processing method described in this application; Figure 8 This is a flowchart illustrating the buffer action triggering moment of the sapphire crystal rod processing method described in this application; Figure 9 This is a flowchart illustrating the buffer action triggering time interval of the sapphire crystal rod processing method described in this application.

[0008] Explanation of reference numerals in the attached drawings: 100, clamping mechanism; 200, grinding mechanism; 210, base; 220, grinding wheel; 221, feed end; 222, output end; 230, buffer; 240, collection component; 300, sapphire crystal rod. Detailed Implementation

[0009] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0010] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0011] To better understand the above technical solutions, a detailed description of the technical solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0012] Sapphire crystals, with their superior properties such as high hardness, high light transmittance, and good chemical stability, are widely used in high-end fields such as semiconductor substrates, optical devices, and window materials. After crystal growth and directional rod-making, the resulting sapphire crystal rods (300) are not standard cylindrical structures, and generally exhibit forming defects such as overall eccentricity, multi-faceted outer contours, and localized abrupt protrusions on the surface.

[0013] Sapphire material possesses inherent material characteristics of extremely high hardness, high brittleness, and no ability to undergo plastic deformation. It is highly sensitive to instantaneous impact loads from the outside world and cannot dissipate grinding impact stress through plastic deformation. In the processing technology, the blank crystal rod after being hollowed out is generally directly fed into a rounding machine for rotary rounding. On the one hand, the overall outline of the crystal rod is irregular and the allowance on multiple sides is unevenly distributed. Direct rounding requires the grinding wheel 220 to repeatedly pass and dress the tool with a small depth of cut and a low feed rate. The total grinding allowance is large, the processing cycle is long, and the production efficiency is extremely low. At the same time, long-term high-load grinding will aggravate the wear of the grinding wheel 220 and equipment wear, pushing up the overall processing cost. On the other hand, the local steep protrusions on the surface of the crystal rod will generate instantaneous rigid hard impacts with the high-speed rotating grinding wheel 220 during the crystal rod rotation. The sharp corners and edges form single-point concentrated loads. The impact stress is directly applied to the root of the protrusion, which can easily cause appearance defects such as protrusion chipping, edge chipping, and surface peeling. At the same time, it can also cause hidden microcracks to incubate inside the crystal rod. These microcracks are non-removable and will continue to expand and spread during subsequent slicing, grinding, and polishing processes, significantly reducing the yield and reliability of sapphire wafers.

[0014] To address the aforementioned technical problems, this application proposes a sapphire crystal processing method, which pre-grinds the sapphire crystal ingot 300 before rounding it; the sapphire crystal processing method is applicable to sapphire crystal ingot 300 processing equipment, such as... Figure 1 , 2 As shown, the sapphire crystal rod 300 processing device includes a clamping mechanism 100 and a grinding mechanism 200. The clamping mechanism 100 clamps and fixes both ends of the crystal rod, keeping the crystal rod stationary and non-rotating throughout the process. The grinding mechanism 200 is equipped with a self-rotating grinding wheel 220, which is arranged on the side of the crystal rod and can move linearly along the length of the crystal rod to achieve axial linear pre-grinding before the rounding process.

[0015] like Figure 3 As shown, the sapphire crystal processing method includes: S1: clamping and fixing both ends of the sapphire crystal rod 300 by the clamping mechanism 100, so that the sapphire crystal rod 300 remains stationary; S2: Control the grinding wheel 220 to rotate around its own axis and make the grinding wheel 220 contact the side of the sapphire crystal rod 300 for grinding; S3: Control the grinding wheel 220 to move linearly along the length of the sapphire crystal rod 300 to perform axial linear pre-grinding on the side of the sapphire crystal rod 300. The axial linear pre-grinding process is performed before the sapphire crystal rod 300 rounding process.

[0016] In other words, the clamping mechanism 100 is used for clamping and positioning the sapphire crystal rod 300. The clamping mechanism 100 clamps and limits the sapphire crystal rod 300 from both ends along its length, and locks the spatial posture of the crystal rod through mechanical clamping and positioning. The grinding mechanism 200 includes a base 210 and a grinding wheel 220. The grinding wheel 220 is mounted on the base 210 and is arranged on the outer side of the sapphire crystal rod 300. The grinding wheel 220 has a degree of freedom of motion to rotate around its central axis. The grinding wheel 220 performs grinding and cutting operations on the side of the crystal rod by rotating itself. The base 210 has linear movement capability. The base 210 can be displaced along a preset first direction, which is parallel to the length direction of the sapphire crystal rod 300. The grinding wheel 220 is controlled to rotate continuously around its own central axis, so that the outer peripheral grinding surface of the grinding wheel 220 keeps in close contact with the side of the sapphire crystal rod 300, thus establishing the grinding cutting condition. On this basis, the base 210 is controlled to drive the grinding wheel 220 to move in a uniform linear motion along the length of the sapphire crystal rod 300. While rotating, the grinding wheel 220 follows the axial movement of the base 210 to perform continuous axial linear pre-grinding operation on the side of the sapphire crystal rod 300.

[0017] It should be noted that a pre-processing straight-line grinding step is added before the sapphire ingot 300 rounding process to solve the problems of irregular ingot contour and large overall allowance after ingot removal, thereby reducing the difficulty of subsequent rounding and improving production efficiency. The ingot after ingot removal is not a standard cylinder, and small local protrusions are easily left on the side wall. If it directly enters the rounding process, the grinding wheel 220 will have to bear a large amount of grinding allowance, and repeated low-speed tool dressing is required. This not only results in a long processing cycle and low efficiency, but also aggravates the wear of the grinding wheel 220 and increases processing costs. Therefore, pre-processing grinding is a necessary pre-processing step to achieve efficient rounding.

[0018] This application sets the axial linear pre-grinding process before the sapphire ingot 300 rounding process, forming a process combination of pre-treatment and subsequent rounding. If the sapphire ingot 300 after being hollowed out is directly rounded, the grinding wheel 220 needs to consume a lot of time to dress the overall allowance, which greatly increases the equipment load and processing time. This application, through pre-linear grinding before rounding, first pre-treats the large-area overall irregular contour of the ingot, reduces most of the grinding allowance, and makes the ingot contour initially more regular, which greatly reduces the processing difficulty and grinding load of the subsequent rounding process, and improves the overall processing efficiency from the source of the process.

[0019] Furthermore, such as Figure 4 , 5 As shown, the grinding mechanism 200 also includes a buffer 230, which, through the acquisition of protrusion parameters, determination of trigger time, and control of flexible buffer execution, addresses the problem of instantaneous impact stress concentration on the surface of the crystal rod with abrupt protrusions, and solves the problem of easy breakage and microcracks during protrusion grinding.

[0020] Understandably, the purpose of pre-grinding is to homogenize the overall contour, rather than to refine single-point protrusions. The working condition is that the 220 grinding wheel continuously moves along the crystal rod axis, focusing on trimming large areas of irregular excess material, so that the crystal rod contour is initially shaped, reducing the burden on the subsequent rounding process. However, the local protrusions left after the rod is hollowed out are mostly sharp-angled and abruptly changed structures with obvious stress concentration at the root. Moreover, sapphire has extremely high hardness, extremely high brittleness, and no plastic deformation ability. If the 220 grinding wheel rigidly impacts the protrusion under the pre-grinding continuous fast-moving condition, it will instantly generate concentrated impact load, which can easily cause the protrusion area to chip or break off, and may also induce hidden microcracks in the surface and internal layers. Such defects cannot be eliminated by subsequent processes and will seriously affect the yield of subsequent slicing.

[0021] Therefore, when encountering protrusions during pre-grinding, flexible avoidance is necessary. This does not mean abandoning processing, but rather avoiding the inherent contradiction between the process conditions and material properties. The high-efficiency grinding conditions of continuous fast feed are inherently unsuitable for rigid finishing of sharp-angled and steep protrusions. The role of the 220 grinding wheel in avoiding this is to prevent hard impact between the 220 grinding wheel and the protrusion, protecting the crystal matrix from damage and preventing micro-cracks, while not affecting the overall contour homogenization of the pre-grinding. After avoidance, the protrusions are individually finished, and the axial position and height of all avoided protrusions are recorded. After the overall pre-grinding is completed, the process is switched to a dedicated finishing condition with low speed, small depth of cut, and layered micro-feed. Each protrusion is individually aligned and ground layer by layer, which not only completely eliminates the protrusions but also avoids the defects caused by rigid impact. This forms a process of pre-grinding homogenization and load reduction, avoidance to prevent breakage, and individual finishing to ensure quality. It solves the problem of low efficiency of direct rounding and also overcomes the problem of easy breakage during protrusion grinding.

[0022] Specifically, based on the above-mentioned grinding mechanism 200, a buffer 230 and a data acquisition device 240 are added. The buffer 230 is assembled and connected between the base 210 and the grinding wheel 220. As a flexible adjustment actuator, it can finely adjust the radial distance between the grinding wheel 220 and the side of the sapphire crystal rod 300. By adjusting the distance, the grinding wheel 220 can flexibly buffer and avoid the protrusions on the surface of the crystal rod, thus avoiding rigid direct impact. The data acquisition device 240 is a sensor for protrusion information. The data acquisition device 240 is fixedly arranged in front of the grinding wheel 220 as it moves in the first direction. The data acquisition device 240 and the grinding wheel 220 maintain a fixed relative distance, and the data acquisition device 240 is rigidly linked with the grinding wheel 220. It can move axially linearly synchronously with the grinding wheel 220 to detect the surface contour of the crystal rod on the grinding path in front of the grinding wheel 220, so that the data acquisition device 240 can continuously acquire the protrusion parameters of the outer circle of the sapphire crystal rod 300 on the grinding path in front of the grinding wheel 220. In one embodiment, the collecting element 240 may be fixedly connected to the base 210 so that the collecting element 240 moves synchronously with the grinding wheel 220.

[0023] like Figure 6 , 7 As shown, the sapphire crystal processing method also includes: T11: Collect the protrusion parameters of the outer circle of the sapphire crystal rod 300 on the grinding path in front of the grinding wheel 220. The protrusion parameters include the axial position of the protrusion and the height of the protrusion. T12: Determine the triggering time of the buffer 230 based on the position of the grinding wheel 220, the moving speed of the grinding wheel 220, and the protrusion parameters; T13: Causes the buffer 230 to perform the buffering action of the grinding wheel 220 on the protrusion at the trigger time.

[0024] During the pre-grinding process, the grinding wheel 220 grinds the sapphire ingot 300, while the acquisition unit 240 collects the protrusion parameters on the forward path, and the buffer unit 230 performs buffering and adjustment of the grinding wheel 220. Specifically, the acquisition unit 240, which moves synchronously with the grinding wheel 220, collects the protrusion parameters of the outer circle of the sapphire ingot 300 on the forward path of the grinding wheel 220. The collected protrusion parameters mainly include the axial position of the protrusion in the length direction of the ingot and the protrusion height of the protrusion relative to the standard outer circle of the ingot. After obtaining the protrusion parameters, the triggering time of the buffer unit 230 is calculated by combining the real-time axial position of the grinding wheel 220, the linear movement speed of the grinding wheel 220 along the first direction, and the collected protrusion characteristic parameters through preset control logic. When the system reaches the calculated triggering time, the buffer unit 230 is controlled to move, fine-tuning the distance between the grinding wheel 220 and the ingot, and performing a flexible buffering and avoidance action of the grinding wheel 220 on the protrusion.

[0025] The height of the protrusion acquired by the acquisition device 240 is determined based on the theoretical standard cylindrical surface of the sapphire crystal rod 300 as a reference surface, specifically referring to the radial deviation of the protrusion apex on the crystal rod surface relative to this theoretical cylindrical surface. In one embodiment, the acquisition device 240 is a laser rangefinder, a 3D structured light vision camera, or a 3D laser contour camera.

[0026] It should be noted that, as Figure 6 , 7 As shown, the local protrusions formed after the sapphire ingot 300 are mostly steeply angled structures with a natural stress concentration effect at the root. Furthermore, sapphire possesses high hardness, high brittleness, and no plastic deformation, making it sensitive to instantaneous external impact loads. During the linear feed grinding process of the grinding wheel 220 along the ingot axis, the feed end 221 of the grinding wheel 220 is the cutting edge. When the protrusion first reaches the feed end 221 of the grinding wheel 220, the contact area is extremely small, and the load is highly concentrated. The impact stress generated by the high-speed grinding of the grinding wheel 220 directly acts on the root of the protrusion's sharp corner, easily causing protrusion chipping and edge breakage. The initiation of microcracks in the block and its interior is the moment with the greatest stress and the most likely to produce machining defects during the entire grinding process. When the protrusion passes the feed end 221 of the grinding wheel 220 and completely enters the axially covering wide interior of the grinding wheel 220, the contact between the protrusion and the grinding wheel 220 changes from a single-point line contact to a small-area surface contact and enveloping grinding state. The force changes from instantaneous concentrated impact to uniform and slow-release grinding stress. There is no sudden load or sharp corner stress concentration. At this time, it can be set that there is no need to continue flexible avoidance. Conventional rigid grinding can be used to stably dress the protrusion contour, which will not produce chipping defects and can ensure grinding efficiency and dressing accuracy.

[0027] Thus, by flexibly avoiding the protrusion only at the moment it enters the feed end 221 of the grinding wheel 220, the greatest risk point can be avoided; after entering the width of the grinding wheel 220, normal grinding resumes, preventing breakage and suppressing cracks while taking into account the processing efficiency of the preceding straight grinding; the protrusion only experiences a sharp, single-point hard impact at the moment it first touches the feed end 221 of the grinding wheel 220, when the stress is greatest and it is most prone to breakage, so it must be avoided; once the protrusion enters the width of the grinding wheel 220, it becomes a surface contact with uniform force, and there is no instantaneous impact, so there is no need to avoid it, and normal grinding can proceed; this embodiment, through buffer control, matches the dangerous working condition of the protrusion impact, and achieves flexible avoidance between the grinding wheel 220 and the crystal rod at critical moments, taking into account both processing quality and processing efficiency.

[0028] In a preferred embodiment, the guide structure is fixedly mounted on the base 210, and the floating slide seat slides with the base 210 through the guide structure. The floating slide seat can reciprocate slightly along the radial direction of the sapphire crystal rod 300. The grinding wheel 220 is fixedly mounted on the floating slide seat. The buffer 230 is a magnetic fluid and is disposed between the base 210 and the floating slide seat. It is used to adjust the support stiffness and buffer damping of the floating slide seat to cooperate with the grinding wheel 220 to flexibly avoid protrusions. In this way, a rigid guide structure and a radial floating telescopic structure are added between the base 210 and the grinding wheel 220. The guide structure bears the grinding load and attitude constraint, limiting the grinding wheel 220 to only make slight floating along the radial direction of the crystal rod. The floating telescopic structure provides a preset avoidance stroke. The magnetic fluid buffer 230 only acts within the floating stroke to achieve continuously adjustable stiffness and impact damping buffer.

[0029] Furthermore, such as Figure 6 , 7 As shown, the calculation of the triggering time of the buffer 230 is quantitatively limited. By establishing the relationship between the protrusion position, the grinding wheel 220 position, and the moving speed, the buffer triggering time is solved, reducing the judgment error and ensuring that the buffering action matches the moment when the protrusion enters the grinding wheel 220. Specifically, the triggering time of the buffer 230 is determined based on the grinding wheel 220 position, the grinding wheel 220 moving speed, and the protrusion parameters, including: Triggering time of buffer 230:

[0030] The protrusion is located at the axial position of the crystal rod; The feed end 221 of the grinding wheel 220 is positioned along the crystal rod axis; The moving speed of the grinding wheel 220 in the first direction; Triggering time of buffer 230 When the grinding wheel 220 moves to the point where the protrusion coincides with the axial position of the feed end 221 of the grinding wheel 220, the trigger is activated. The punch performs a buffering action.

[0031] By dividing the difference in axial position between the protrusion and the feed end 221 of the grinding wheel 220 by the uniform moving speed of the grinding wheel 220, the time required for the grinding wheel 220 to travel until the axial position of the protrusion and the feed end 221 of the grinding wheel 220 coincides is obtained. The calculated time... This is the trigger moment of buffer 230; during actual processing and operation, data is collected in real time. and Coordinate data (where, (This can be calculated using the stroke of grinding wheel 220 and the width of grinding wheel 220 itself), combined with the moving speed of grinding wheel 220. The trigger time can be calculated. When the equipment runs delayed Then, the buffer 230 is immediately triggered to perform the buffering action.

[0032] By calculating the trigger moment, the critical working condition of the protrusion just arriving at the feed end 221 of the grinding wheel 220 can be captured. The flexible buffer is activated at the moment when the instantaneous impact of the single-point edge is about to occur, which is in line with the dangerous characteristics of stress concentration of sapphire protrusion. Compared with traditional control methods such as fuzzy delay trigger and fixed position trigger, the calculation method of this embodiment has no time lag and no position deviation. The buffer action matches the impact condition, avoiding instantaneous impact load to the greatest extent and preventing protrusion breakage and microcrack generation.

[0033] In another embodiment, an optimized single-point buffering scheme is implemented at the instant the protrusion enters the feed end 221. This is achieved by defining a continuous buffering trigger interval based on the axial width of the grinding wheel 220, ensuring that the buffer 230 maintains its buffering function throughout the entire period when the protrusion is within the full width coverage of the grinding wheel 220. Figure 8 As shown, it includes: T21: Collect the protrusion parameters of the sapphire ingot 300 on the outer diameter of the grinding path in front of the grinding wheel 220. The protrusion parameters include the axial position of the protrusion on the ingot. and protrusion height ; T22: Determine the triggering time range of the buffer 230 based on the position of the grinding wheel 220, the moving speed of the grinding wheel 220, the protrusion parameters, and the width of the grinding wheel 220; T23: Causes the buffer 230 to perform the buffering action of the grinding wheel 220 on the protrusion during the triggering time interval.

[0034] The acquisition element 240, which moves synchronously with the grinding wheel 220, continuously acquires the protrusion parameters of the outer circle of the sapphire ingot 300 on the grinding path in front of the grinding wheel 220, so as to measure the axial position of the protrusion on the ingot. and protrusion height To collect parameters, after the parameters are collected, the axial width of the grinding wheel 220 itself is introduced as a calculation variable. Based on the position, moving speed, and protrusion parameters of the grinding wheel 220 and the width of the grinding wheel 220, a continuous buffer trigger time interval is defined. After the time interval is determined, the buffer component 230 is controlled to maintain the trigger state throughout the entire trigger time interval, that is, to perform the buffer avoidance action of the grinding wheel 220 on the protrusion until the protrusion is completely removed from the coverage area of ​​the width of the grinding wheel 220.

[0035] Furthermore, the start and end points of the time interval are quantified. Using the position parameters of the feed end 221 and the exit end 222 of the grinding wheel 220, the start and end times of the buffer are calculated, thereby determining the duration of the buffer and achieving a closed-loop buffer throughout the entire axial width of the grinding wheel 220. Specifically, based on the position of the grinding wheel 220, its moving speed, the protrusion parameters, and the width of the grinding wheel 220, the trigger time interval of the buffer element 230 is determined as follows: The start time of the trigger time interval and end time :

[0036]

[0037] The protrusion is located at the axial position of the crystal rod; The feed end 221 of the grinding wheel 220 is positioned along the crystal rod axis; The cutting end 222 of the grinding wheel 220 is positioned along the crystal rod axis. The moving speed of the grinding wheel 220 in the first direction; The triggering time interval of buffer 230 is From the moment the protrusion reaches the feed end 221 of the grinding wheel 220 until the protrusion leaves the feed end 222 of the grinding wheel 220, the buffer 230 continuously performs the buffering action.

[0038] Start time The physical meaning of "time point" is the time when the grinding wheel 220 moves to the point where the protrusion just reaches the feed end 221 of the grinding wheel 220, serving as the starting point of the buffer action; the ending point is... The physical meaning is the time point at which the grinding wheel 220 moves to the point where the protrusion is about to disengage from the cutting end 222 of the grinding wheel 220, which serves as the termination point of the buffering action; thus, the triggering time interval of the buffer element 230 is determined as follows. This time interval fully covers the entire process from the protrusion entering the feed end 221 of the grinding wheel 220, fully entering the wide interior of the grinding wheel 220, until it leaves the feed end 222 of the grinding wheel 220.

[0039] Throughout During the time interval, the buffer 230 maintains a flexible buffer state, and the grinding wheel 220 continuously yields and avoids the protrusion, thus preventing the grinding wheel 220 from making rigid contact impact with the protrusion throughout the entire process. Compared with single-point instantaneous buffering, full-range buffering can completely eliminate the impact load during the entire process of the protrusion contacting the grinding wheel 220, and avoid the problems of chipping, breakage and micro-crack formation in all aspects, thereby further improving the processing yield.

[0040] It should be noted that in actual industrial processing, the surface of the crystal rod has a large number of low and tiny protrusions. These protrusions are extremely low in height, and the impact stress generated when they come into contact with the grinding wheel 220 is minimal, which will not cause chipping or microcrack defects. If the buffer action is activated for all protrusions, the buffer mechanism will be frequently triggered, disrupting the normal grinding rhythm and reducing the overall processing efficiency. Whether it is single-point buffering by the buffer component 230 when the protrusion is about to reach the feed end 221 of the grinding wheel 220, or interval buffering for the protrusion within a wide range of the grinding wheel 220, it is generally necessary to set a protrusion height threshold. The calculation of the buffer trigger time interval and the execution of the buffer action are only activated when the collected protrusion height is greater than or equal to the preset protrusion height threshold. For tiny protrusions with a protrusion height lower than the threshold, there is no need to activate the buffer control, and conventional rigid grinding can be used directly. By filtering by height threshold, the efficiency loss caused by ineffective buffering is avoided, ensuring processing quality and efficiency.

[0041] Furthermore, a correlation control system is established for the protrusion height, the target retraction amount of the grinding wheel 220, the magnetofluid stiffness, and the excitation current to achieve continuous and controllable adjustment of the buffer stiffness; specifically, the buffer component 230 is a magnetofluid; such as Figure 9 As shown, the method also includes: T31: Based on the collected protrusion height, determine the target yield amount of the grinding wheel 220 for the protrusion; T32: Determine the required stiffness of the magnetohydrodynamic fluid based on the target relief amount of the grinding wheel 220; T33: Determine the excitation current for the magnetic fluid based on the required stiffness and parameters of the magnetic fluid itself; T34: An excitation current is supplied to the excitation coil of the magnetofluid to make the magnetofluid reach the required stiffness so that the grinding wheel 220 can provide a flexible buffer against the protrusion.

[0042] In one embodiment, the buffer 230 is a magnetorheological fluid, which is a smart material with controllable rheological properties in a magnetic field. Under the action of an external excitation magnetic field, the apparent stiffness and viscosity of the magnetorheological fluid can change continuously and smoothly with the magnetic field strength, without mechanical transmission gaps or sudden changes in gear, making it suitable for the flexible buffering scenario in this embodiment. By adjusting the current flowing through the excitation coil, the stiffness characteristics of the magnetorheological fluid can be changed, thereby fine-tuning the radial distance between the grinding wheel 220 and the sapphire crystal rod 300 or the distance that allows for buffering and avoidance, to achieve flexible buffering and avoidance of the protrusion.

[0043] Specifically, the acquisition component 240 obtains the precise height of the protrusion. Based on the protrusion height, the grinding wheel 220 is matched with the target retraction amount required for the protrusion. The retraction amount is used to compensate for the radial height of the protrusion and avoid rigid contact between the grinding wheel 220 and the sharp corner of the protrusion. Then, based on the calculated target retraction amount of the grinding wheel 220, the required working stiffness of the magnetic fluid is matched in reverse. The larger the retraction amount, the higher the required flexibility of the magnetic fluid, and the lower the corresponding working stiffness. The smaller the retraction amount, the higher the stiffness of the magnetic fluid can be maintained, ensuring grinding stability. Furthermore, combining the inherent parameters of the magnetofluid itself, including the viscosity of the magnetofluid base fluid, the ratio of magnetic particles, and the saturation magnetization intensity, the magnitude of the excitation current matching the target working stiffness is calculated. The calculated excitation current is then passed into the excitation coil that is matched with the magnetofluid, and the excitation coil generates a magnetic field of corresponding intensity, so that the rheological adjustment of the magnetofluid is adjusted to the set working stiffness. Relying on the flexible deformation of the magnetofluid, the grinding wheel 220 is driven to produce a slight retraction displacement, and finally the grinding wheel 220 provides flexible buffering for the crystal rod protrusion.

[0044] This embodiment uses magnetofluid as a buffer carrier, replacing the limitations of traditional mechanical springs, elastic pads and other fixed stiffness buffer components, to achieve continuous adjustment of buffer stiffness and match the degree of buffering according to the height characteristics of different protrusions.

[0045] More specifically, based on the target retraction amount of the grinding wheel 220, the working stiffness of the magnetohydrodynamic fluid, and the calculation formula for the excitation current, a mathematical model is established between the protrusion height and the buffer control parameters. Automatic parameter conversion is achieved through preset calibration coefficients to ensure the matching of buffer parameters. Specifically, the target retraction amount of the grinding wheel 220... :

[0046] The amount of retraction of the grinding wheel 220 towards the protruding target represents the radial displacement distance that the grinding wheel 220 needs to move away from the standard outer circle of the crystal rod. The process fitting coefficient, without theoretical derivation, was obtained through multiple calibrations using actual grinding prototypes of sapphire crystal rods 300, and is a fixed process constant. The measured height of the protrusion is for sample 240; based on the formula. The target relief amount of the grinding wheel 220 is linearly positively correlated with the protrusion height. The higher the protrusion height, the greater the radial relief amount required, and the stronger the matching buffer flexibility, which meets the actual grinding process requirements. Stiffness of magnetohydrodynamics :

[0047] This represents the rated maximum stiffness without any protrusions. This is the stiffness attenuation coefficient; The real-time working stiffness after magnetohydrodynamic adjustment; The rated maximum stiffness of the magnetofluid under normal grinding conditions without protrusions is the reference stiffness value for the magnetofluid during normal operation. This is the stiffness attenuation coefficient, a constant parameter preset and calibrated before the equipment leaves the factory; based on the formula... This reflects the negative correlation between magnetohydrodynamic stiffness and target yield, yield amount The larger the value, the greater the decrease in magnetohydrodynamic stiffness, the higher its own flexibility, and the more obvious the buffering and avoidance effect.

[0048] Excitation current :

[0049] The excitation current supplied to the excitation coil; , The calibration constants for the magnetofluid and excitation coil system are determined by the joint calibration of hardware circuit parameters and the electromagnetic characteristics of the magnetofluid, and are stored in the control system.

[0050] Excitation current radial height of the protrusion As the current increases, the magnetic field strength of the excitation coil decreases, and the magnetohydrodynamic stiffness decreases accordingly. The radial clearance of the grinding wheel 220 further increases, accurately achieving adaptive flexible avoidance for high protrusions with large buffer and low protrusions with small buffer. No manual parameter setting is required, adapting to the buffering needs of protrusions of different heights.

[0051] This application further introduces the axial depth of the protrusion entering the grinding wheel 220 as a control variable, and constructs a linear gradual mathematical model of magnetohydrodynamic stiffness and excitation current. This enables the magnetohydrodynamic stiffness to gradually and smoothly harden from its softest state as the protrusion moves from the feed end 221 of the grinding wheel 220 to its complete entry into the wide interior of the grinding wheel 220. This avoids secondary stress impact caused by sudden stiffness changes and further enhances the process effect of preventing chipping and suppressing cracks.

[0052] Specifically, it also includes: when the protrusion enters the feed end 221 of the grinding wheel 220, the stiffness of the magnetofluid and the excitation current change linearly with the depth of the protrusion entering the grinding wheel 220, so that the stiffness of the magnetofluid gradually hardens with the depth of the protrusion entering the grinding wheel 220. Calculate the axial depth of the protrusion entering the grinding wheel 220. :

[0053] Gradual variation formula for magnetohydrodynamic stiffness:

[0054] Gradual change in excitation current:

[0055] in, , For grinding wheels with a width of 220mm; The minimum stiffness of the magnetohydrodynamic fluid; This represents the rated maximum stiffness without any protrusions. , This is the calibration constant for the magnetohydrodynamic coil.

[0056] After the protrusion enters the feed end 221 of the grinding wheel 220, this embodiment no longer maintains the fixed buffer stiffness of the magnetofluid. Instead, it adjusts the working stiffness and excitation current value of the magnetofluid synchronously and linearly according to the axial depth change of the protrusion entering the grinding wheel 220, so that the magnetofluid as a whole exhibits a smooth gradual change characteristic from soft to hard. First, the axial depth parameter of the protrusion entering the grinding wheel 220 is defined. The calculation formula is: This parameter characterizes the straight-line distance of the protrusion cutting into the axial width of the grinding wheel 220 from the feed end 221, directly reflecting the contact process between the protrusion and the grinding wheel 220; it also limits the effective range of the axial depth. ,in Defined as the effective axial width of the grinding wheel 220.

[0057] The formula for calculating the linear gradual change in magnetohydrodynamic stiffness is as follows: In the formula This represents the minimum adjustable stiffness of the magnetofluid, corresponding to the softest working state of the magnetofluid. The rated maximum stiffness under the condition of no protrusion is defined with parameters consistent with those in the aforementioned embodiments; this formula establishes a linear relationship between stiffness and penetration depth, and the stiffness value increases with... Increase the uniform lifting speed.

[0058] The excitation current changes gradually in sync with the stiffness, and the calculation formula is as follows: The calibration constant of the magnetohydrodynamic coil is used. , This ensures a unified electrical control parameter system.

[0059] When axial depth When the value is 0, it means that the protrusion is just in contact with the feed end 221 of the grinding wheel 220, which is the dangerous point of maximum instantaneous impact. At this time, the magnetohydrodynamic fluid maintains minimum stiffness. It is in its softest working state, maximizing the dissipation of single-point impact stress at sharp corners; when the axial depth The value is equal to the width of the grinding wheel (220mm). At this point, the protrusion has fully entered the axially covered wide interior of the grinding wheel 220, the contact state has changed from single-point impact to uniform surface contact, the risk of stress concentration has been completely eliminated, and the magnetohydrodynamic fluid automatically recovers to its rated maximum stiffness. Switch to conventional rigid grinding mode; from 0 to Within the specified range, the magnetofluid stiffness increases linearly and smoothly, avoiding secondary stress fluctuations caused by abrupt changes in stiffness, and further preventing bulging and cracking as well as the propagation of internal microcracks.

[0060] In another embodiment, an axial wear gradient correction coefficient for the grinding wheel 220 is introduced to construct a nonlinear gradual hardening model with two variables: depth of cut and local wear. This model is adapted to the actual working condition where the wear at the feed end 221 of the grinding wheel 220 is large and the wear at the exit end 222 is small after long-term use, thereby improving the engineering adaptability and service life of the process. It also includes: when the protrusion enters the feed end 221 of the grinding wheel 220, the magnetohydrodynamic stiffness is nonlinearly gradually hardened based on the axial depth of the protrusion and the wear gradient of the grinding wheel 220. The wear amount at the feed end 221 of grinding wheel 220 was obtained based on the cumulative working time and cumulative grinding stroke of grinding wheel 220. Wear at the cutter end 222 And satisfy > The wear of the grinding wheel 220 decreases gradually along the axial direction from the infeed end 221 to the exit end 222; Calculate the axial depth of the protrusion entering the grinding wheel 220. :

[0061] , For grinding wheels with a width of 220mm; Grinding wheel 220 wear gradient correction factor :

[0062] This refers to the local wear amount at the location where the protrusion enters the axial depth. These are the initial calibration reference coefficients; Gradual variation formula for magnetohydrodynamic stiffness:

[0063] Gradual change in excitation current:

[0064] The minimum stiffness of the magnetohydrodynamic fluid; This represents the rated maximum stiffness without any protrusions. , This is the calibration constant for the magnetohydrodynamic coil.

[0065] During long-term continuous grinding operations, the wear degree of the grinding wheel 220 varies significantly at different axial positions. The infeed end 221 of the grinding wheel 220, as the area that first contacts the blank ingot and the protrusion, is subjected to large-mass grinding and instantaneous impact loads for a long time, and its wear rate is much higher than that of the exit end 222. On the other hand, the exit end 222 only grinds the surface of the ingot that has been preliminarily dressed, with a small grinding allowance and low impact load, and its wear is much less than that of the infeed end 221. Overall, the wear of the infeed end 221 of the grinding wheel 220 is significantly greater. Wear greater than 222 at the cutter end The distribution pattern is such that the wear amount decreases continuously in a gradient from the infeed end 221 to the exit end 222 along the axial direction of the grinding wheel 220.

[0066] To accurately obtain the wear parameters of the grinding wheel 220, this embodiment uses big data on equipment operation to calibrate the working conditions based on two main operating parameters: the cumulative working time of the grinding wheel 220 and the cumulative grinding stroke. The reference wear amount of the infeed end 221 of the grinding wheel 220 is then calibrated. Wear amount relative to the 222 reference point at the cutter end To determine the local wear at any axial position of the grinding wheel 220, this embodiment employs a linear interpolation model, pre-calibrating the wear at the feed end 221 based on the cumulative working time and cumulative grinding stroke of the grinding wheel 220. Wear at the cutter end 222 Then, linear interpolation is performed along the 220mm axial width of the grinding wheel to obtain the arbitrary axial depth. Corresponding local wear amount This enables parameter solving without additional wear sensors, reducing equipment modification costs.

[0067] This embodiment uses the formula for calculating the axial depth of the protrusion entering the grinding wheel 220. The range of values ​​is , The axial width of the grinding wheel is 220.

[0068] Introducing a wear gradient correction factor for grinding wheel 220 The calculation formula is: In the formula These serve as the initial calibration reference coefficients, used to normalize the correction interval and ensure that the values ​​of the correction coefficients are reasonable and controllable. This represents the local wear at the 220 position on the grinding wheel corresponding to the current protrusion depth.

[0069] After introducing the wear correction factor, the nonlinear gradual variation formula for magnetohydrodynamic stiffness is: Excitation current Conversion relationship, minimum stiffness of magnetohydrodynamics Rated maximum stiffness Coil calibration constant , All parameters are consistent with those in the aforementioned embodiments.

[0070] In this way, the magnetohydrodynamic stiffness is adaptively adjusted according to the depth of penetration of the protrusion and the local wear of the grinding wheel 220. The greater the local wear at the corresponding position of the grinding wheel 220, the greater the correction coefficient. The smaller the value, the lower the working stiffness of the magnetohydrodynamic fluid and the stronger the buffering flexibility, making it suitable for the strong buffering needs of severely worn areas; the smaller the local wear of the 220 grinding wheel, the better the correction coefficient. The larger the value, the higher the magnetohydrodynamic stiffness, restoring the normal grinding state. Through wear gradient correction, it can adapt to different working conditions of new grinding wheel 220, moderately worn grinding wheel 220, and heavily worn grinding wheel 220. No manual replacement of grinding parameters is required, which effectively solves the problem of buffer matching failure and easy breakage after the grinding wheel 220 wears.

[0071] In other embodiments, based on the magnetohydrodynamic buffer, two controllable variables, namely the axial depth of the protrusion and the height of the protrusion, are introduced simultaneously. A protrusion height gradual correction coefficient is added to construct a bivariate nonlinear gradual hardening model. The gradual rate of change of the magnetohydrodynamic stiffness is automatically matched according to the height of the protrusion itself. High protrusions slow down the gradual process and extend the buffer time, while low protrusions speed up the gradual process to ensure processing efficiency. It also includes: when the protrusion enters the feed end 221 of the grinding wheel 220, the stiffness of the magnetohydrodynamic fluid exhibits nonlinear gradual hardening with the axial depth of the protrusion entering the grinding wheel 220 and the height of the protrusion. Calculate the axial depth of the protrusion entering the grinding wheel 220. :

[0072] , For grinding wheels with a width of 220mm; Magnetohydrodynamic stiffness gradual correction factor :

[0073] These are the process fitting coefficients; Gradual variation formula for magnetohydrodynamic stiffness:

[0074] Gradual change in excitation current:

[0075] The minimum stiffness of the magnetohydrodynamic fluid; This represents the rated maximum stiffness without any protrusions. , This is the calibration constant for the magnetohydrodynamic coil.

[0076] After the protrusion enters the feed end 221 of the grinding wheel 220, the hardening process of the magnetic fluid is no longer determined solely by the depth of cut, but also follows the axial depth. With the height of the protrusion Nonlinear gradual hardening is performed; axial depth is adopted. Perform calculations, range of values , The grinding wheel has an axial width of 220mm; to achieve differentiated control of the protrusion height, a magnetohydrodynamic stiffness gradual correction coefficient is constructed. The calculation formula is: In the formula Using the process fitting coefficients from the previous embodiments to maintain the uniformity of the entire parameter system, the correction coefficient values ​​vary with the height of the protrusion. Increase the synchronous linearity boost.

[0077] The nonlinear gradual variation formula for magnetohydrodynamic stiffness based on bivariate regulation is as follows: The excitation current is converted synchronously with the stiffness, and the formula is as follows: minimum stiffness of magnetohydrodynamics Rated maximum stiffness Coil calibration constant , All definitions are continued from those in the previous embodiments to ensure consistent control logic.

[0078] This embodiment achieves a negative correlation between the gradual rate of change of magnetohydrodynamic stiffness and the radial height of the protrusion through a height correction coefficient. The larger the protrusion height, the greater the correction coefficient. The larger the value, the gentler the hardening rate of the magnetohydrodynamic stiffness, extending the duration of the soft-state buffer, fully releasing the concentrated impact stress of the steep protrusion, and avoiding the risk of cracking and microcracks; the smaller the protrusion height, the smaller the correction coefficient. The smaller the value, the faster the stiffness change rate, which can quickly break away from the flexible buffer state and switch to the conventional rigid grinding mode, avoiding excessive buffering that occupies processing time and ensuring overall grinding efficiency.

[0079] The adaptive gradient mode of this embodiment can automatically match the buffer rhythm according to the actual height and shape of the protrusions on the surface of the crystal rod, which not only meets the long-term flexible protection requirements of high-risk large protrusions, but also takes into account the high-efficiency grinding requirements of low and risk-free protrusions, thus balancing processing quality and production efficiency.

[0080] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0081] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for processing sapphire crystals, characterized in that, An apparatus for processing sapphire ingots (300), the apparatus comprising: A clamping mechanism (100) is used to clamp the two ends of a sapphire crystal rod (300) along its length. Grinding mechanism (200), the grinding mechanism (200) includes: Base (210); A grinding wheel (220) is disposed on the side of a sapphire crystal rod (300) and connected to a base (210). The grinding wheel (220) is used for grinding the side of the sapphire crystal rod (300) and can rotate around its own axis. The base (210) can move along a first direction, which is the length direction of the sapphire crystal rod (300). Sapphire crystal processing methods include: The clamping mechanism (100) clamps and fixes both ends of the sapphire crystal rod (300) so that the sapphire crystal rod (300) remains stationary. The grinding wheel (220) is controlled to rotate around its own axis and to make the grinding wheel (220) contact the side of the sapphire crystal rod (300) for grinding; The grinding wheel (220) is controlled to move linearly along the length of the sapphire crystal rod (300) to perform axial linear pre-grinding on the side of the sapphire crystal rod (300); The axial linear pre-grinding process is set before the sapphire crystal rod (300) rounding process.

2. The sapphire crystal processing method according to claim 1, characterized in that, The grinding mechanism (200) further includes: A buffer (230) is connected between the base (210) and the grinding wheel (220). The buffer (230) is used to adjust the distance between the grinding wheel (220) and the sapphire crystal rod (300) so that the grinding wheel (220) can buffer the protrusion. The collecting element (240) is located in front of the grinding wheel (220) in a first direction. The collecting element (240) maintains a fixed distance from the grinding wheel (220) and can move synchronously with the grinding wheel (220). The collecting element (240) is used to collect the protrusion parameters of the sapphire crystal rod (300) on the grinding path in front of the grinding wheel (220). Sapphire crystal processing methods also include: Collect the protrusion parameters of the outer circle of the sapphire crystal rod (300) on the grinding path in front of the grinding wheel (220). The protrusion parameters include the position of the protrusion in the axial direction of the crystal rod and the height of the protrusion. Based on the position of the grinding wheel (220), the moving speed of the grinding wheel (220), and the protrusion parameters, the triggering time of the buffer (230) is determined; The buffer (230) performs the buffering action of the grinding wheel (220) on the protrusion at the trigger time.

3. The sapphire crystal processing method according to claim 2, characterized in that, The determination of the triggering time of the buffer (230) based on the position of the grinding wheel (220), the moving speed of the grinding wheel (220), and the protrusion parameters includes: The triggering time of the buffer (230): The protrusion is located at the axial position of the crystal rod; The feed end (221) of the grinding wheel (220) is positioned along the axial direction of the crystal rod; The speed at which the grinding wheel (220) moves in the first direction; The triggering time of the buffer (230) When the grinding wheel (220) moves to the point where the protrusion coincides with the axial position of the feed end (221) of the grinding wheel (220), the buffer is triggered. The punch performs a buffering action.

4. The sapphire crystal processing method according to claim 2, characterized in that, Also includes: The protrusion parameters of the sapphire ingot (300) on the outer circle of the grinding path in front of the grinding wheel (220) are collected. The protrusion parameters include the axial position of the protrusion on the ingot. and protrusion height ; Based on the position of the grinding wheel (220), the moving speed of the grinding wheel (220), the protrusion parameters, and the width of the grinding wheel (220), the triggering time range of the buffer (230) is determined; The buffer (230) performs the buffering action of the grinding wheel (220) on the protrusion during the triggering time interval.

5. The sapphire crystal processing method according to claim 4, characterized in that, The determination of the triggering time interval of the buffer (230) based on the position of the grinding wheel (220), the moving speed of the grinding wheel (220), the protrusion parameters, and the width of the grinding wheel (220) includes: The start time of the trigger time interval and end time : The protrusion is located at the axial position of the crystal rod; The feed end (221) of the grinding wheel (220) is positioned along the axial direction of the crystal rod; The cutting end (222) of the grinding wheel (220) is positioned along the axial direction of the crystal rod; The speed at which the grinding wheel (220) moves in the first direction; The triggering time interval of the buffer (230) is as follows: From the moment the protrusion reaches the feed end (221) of the grinding wheel (220) until the protrusion leaves the feed end (222) of the grinding wheel (220), the buffer (230) continuously performs the buffering action.

6. The sapphire crystal processing method according to claim 2 or 3, characterized in that, The buffer (230) is a magnetofluid; Based on the collected height of the protrusion, determine the target yield amount of the grinding wheel (220) for the protrusion; Based on the target retraction amount of the grinding wheel (220), the required stiffness of the magnetofluid is determined; Based on the required stiffness of the magnetofluid and the magnetofluid's own parameters, the excitation current for the magnetofluid is determined. The excitation current is supplied to the excitation coil of the magnetic fluid to make the magnetic fluid reach the required stiffness so that the grinding wheel (220) can provide a flexible buffer against the protrusion.

7. The sapphire crystal processing method according to claim 6, characterized in that, Target yield of grinding wheel (220) : These are the process fitting coefficients; Stiffness of magnetohydrodynamics : This represents the rated maximum stiffness without any protrusions. This is the stiffness attenuation coefficient; Excitation current : , This is the calibration constant for the magnetohydrodynamic coil.

8. The sapphire crystal processing method according to claim 6, characterized in that, Also includes: When the protrusion enters the feed end (221) of the grinding wheel (220), the stiffness of the magnetofluid and the excitation current change linearly with the depth of the protrusion entering the grinding wheel (220), so that the stiffness of the magnetofluid gradually becomes harder with the depth of the protrusion entering the grinding wheel (220). Calculate the axial depth of the protrusion entering the grinding wheel (220). : Magnetohydrodynamic stiffness : Excitation current : in, , For the width of the grinding wheel (220); The minimum stiffness of the magnetohydrodynamic fluid; This represents the rated maximum stiffness without any protrusions. , This is the calibration constant for the magnetohydrodynamic coil.

9. The sapphire crystal processing method according to claim 6, characterized in that, Also includes: When the protrusion enters the feed end (221) of the grinding wheel (220), the magnetohydrodynamic stiffness undergoes nonlinear gradual hardening based on the axial depth of the protrusion and the wear gradient of the grinding wheel (220); The wear amount at the feed end (221) of the grinding wheel (220) is obtained based on the cumulative working time and cumulative grinding stroke of the grinding wheel (220). Wear at the cutter end (222) And satisfy > The wear of the grinding wheel (220) decreases gradually along the axial direction from the infeed end (221) to the exit end (222); Calculate the axial depth of the protrusion entering the grinding wheel (220). : , For the width of the grinding wheel (220); Grinding wheel (220) wear gradient correction factor : This refers to the local wear amount at the location where the protrusion enters the axial depth. These are the initial calibration reference coefficients; Magnetohydrodynamic stiffness : Excitation current : The minimum stiffness of the magnetohydrodynamic fluid; This represents the rated maximum stiffness without any protrusions. , This is the calibration constant for the magnetohydrodynamic coil.

10. The sapphire crystal processing method according to claim 6, characterized in that, Also includes: When the protrusion enters the feed end (221) of the grinding wheel (220), the stiffness of the magnetohydrodynamic fluid gradually hardens nonlinearly with the axial depth of the protrusion entering the grinding wheel (220) and the height of the protrusion. Calculate the axial depth of the protrusion entering the grinding wheel (220). : , For the width of the grinding wheel (220); Magnetohydrodynamic stiffness gradual correction factor : These are the process fitting coefficients; Magnetohydrodynamic stiffness : Excitation current : The minimum stiffness of the magnetohydrodynamic fluid; This represents the rated maximum stiffness without any protrusions. , This is the calibration constant for the magnetohydrodynamic coil.

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