Real-time monitoring method for abnormal state of magnetorheological polishing

Abstract

The present invention belongs to the technical field of real-time monitoring of optical processing, and in particular relates to a method for real-time monitoring of abnormal conditions of magnetorheological polishing. The method comprises: S1: obtaining ribbon data under the complete magnetorheological polishing process in combination with a displacement sensor; S2: the data processing module calculates the magnetorheological polishing state of the current sampling point based on the ribbon contour vectors corresponding to the adjacent ribbon data; S3: the processing control module determines whether the magnetorheological polishing state display at the current sampling point is normal. If so, magnetorheological polishing is performed on the mirror surface based on the current processing grinding head, and the magnetorheological polishing state at the next sampling point is calculated based on steps S1-S2 until the magnetorheological polishing is completed. Otherwise, the current processing grinding head is processed, and the magnetorheological polishing state at the next sampling point is calculated based on steps S1-S2 until the magnetorheological polishing is completed. The present invention can realize automatic and accurate monitoring of abnormal conditions of magnetorheological polishing.

Description

Technical Field

[0001] The invention belongs to the technical field of real-time monitoring of optical processing, and in particular relates to a real-time monitoring method for abnormal states of magnetorheological polishing. Background Art

[0002] Magnetorheological polishing (MRP) is a representative optical processing technique widely used in the field due to its advantages, such as minimal subsurface damage and high removal efficiency. MR fluid forms a Bingham flow under the influence of a magnetic field, generating shear forces that remove material. Therefore, the stability of the MR polishing ribbon indirectly reflects the stability of the MR polishing process.

[0003] During long, multi-round processes, magnetorheological polishing systems can experience anomalies, such as iron filings blocking the pipes. These anomalies can lead to reduced polishing efficiency at best, or even non-convergent machining results at worst. Therefore, the automation level of real-time monitoring of anomalies during multi-round, long-term magnetorheological polishing needs to be improved.

[0004] The Chinese invention patent entitled "Neural Network-Based Magnetorheological Polishing Removal Function Prediction Device and Method" (publication number CN117556345A, publication date March 12, 2024) predicts a real-time removal function using a ribbon profile. Its purpose is to detect real-time polishing removal efficiency, but its monitoring and judgment capabilities for different abnormal conditions are weak, and it is unable to automatically handle abnormal conditions. Summary of the Invention

[0005] In view of this, the present invention aims to provide a real-time monitoring method for abnormal states of magnetorheological polishing to solve the problem that the existing technology has weak monitoring and judgment capabilities for different abnormal states and cannot automatically handle abnormal states. The present invention establishes a relationship between the ribbon changes in the polishing process and the processing state, thereby realizing automatic and accurate monitoring of abnormal states of magnetorheological polishing.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] A real-time monitoring method for abnormal state of magnetorheological polishing, the method specifically comprises the following steps:

[0008] S1: Combined with the displacement sensor to obtain the ribbon data under the complete magnetorheological polishing process, and the sampling interval between adjacent sampling points is T;

[0009] S2: The data processing module calculates the magnetic streamer polishing state of the current sampling point based on the ribbon contour vectors corresponding to the adjacent ribbon data;

[0010] S3: The processing control module determines whether the magnetofluidic polishing status display at the current sampling point is normal. If so, magnetofluidic polishing is performed on the mirror surface based on the current processing grinding head, and the magnetofluidic polishing status at the next sampling point is calculated based on steps S1-S2 until the magnetofluidic polishing is completed. Otherwise, the current processing grinding head is processed, and the magnetofluidic polishing status at the next sampling point is calculated based on steps S1-S2 until the magnetofluidic polishing is completed.

[0011] Furthermore, in step S2, each ribbon outline vector has a dimension of 1×M.

[0012] Furthermore, in step S2, based on the ribbon contour vectors corresponding to the adjacent sampling points, the formula used to calculate the magnetic streamer polishing state of the current sampling point is:

[0013] (1);

[0014] Where i is the i-th element in the ribbon profile vector, t is the t-th second in the complete magnetorheological polishing process, E is the ribbon profile vector, is the processing speed, For tolerance, This is the ribbon outline when the polishing wheel is outside the mirror surface. This is the ribbon outline when the polishing wheel is in the mirror surface. is the distance between adjacent sampling points, The element number in the ribbon profile vector corresponding to the limit point where the polishing wheel undergoes a sudden change between outside and inside the mirror surface.

[0015] Furthermore, at the current sampling point, when If formula (1) is satisfied, it means that the magnetorheological polishing state is normal; otherwise, it means that the magnetorheological polishing state is abnormal.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0017] The present invention provides a real-time monitoring method for abnormal magnetorheological polishing conditions. This method processes ribbon profile change data collected by displacement sensors during previous processes to model the ribbon's fluctuations during normal processing. When a new magnetorheological polishing monitoring task arises, the ribbon profile change data, acquired by the displacement sensors, is simply fed into a real-time processing algorithm to quickly determine whether the process is abnormal. Compared to traditional manual monitoring methods, this method offers significant automation advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 A flow chart of a method for real-time monitoring of abnormal states of magnetorheological polishing according to an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of the machining trajectory according to an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the processing process described in an embodiment of the present invention;

[0022] Figure 4 A graph showing the profile of a ribbon before processing and the profile of a ribbon in a stable processing state according to an embodiment of the present invention;

[0023] Figure 5 This is a diagram showing the changing process of the ribbon in the edge area according to an embodiment of the present invention;

[0024] Figure 6 This is a diagram showing the slow change process of the ribbon in the edge area according to an embodiment of the present invention.

[0025] Description of reference numerals:

[0026] 1. Processing grinding head; 2. Polishing ribbon; 3. Mirror surface. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0032] The present invention adopts a real-time monitoring system for abnormal state of magnetorheological polishing, comprising:

[0033] Displacement sensor, used to obtain ribbon data under the complete magnetorheological polishing process;

[0034] A data processing module, configured to calculate a corresponding magnetic streamer polishing state based on a ribbon contour vector corresponding to the ribbon data;

[0035] The processing control module is used to determine whether the magnetorheological polishing state display is normal. If so, magnetorheological polishing is performed on the mirror surface 3 based on the current processing grinding head 1. Otherwise, the current processing grinding head 1 is processed.

[0036] The process of obtaining the ribbon data under the complete magnetorheological polishing process by combining the displacement sensor and obtaining the ribbon contour vector based on the ribbon data belongs to the existing technology and will not be described in detail here.

[0037] It should be noted that the present invention collects statistics on the ribbon fluctuations in various normal processes, and then processes the polishing ribbon 2 in the magnetorheological polishing process collected by the displacement sensor through a real-time processing algorithm, outputs the real-time processing status, and then issues an alarm and automatically processes abnormal conditions that occur during the processing. That is, the proposed real-time processing algorithm establishes a relationship between the ribbon changes in the polishing process and the processing status, thereby realizing automated and accurate monitoring of abnormal conditions in magnetorheological polishing.

[0038] like Figure 1 As shown, the present invention proposes a real-time monitoring method for abnormal state of magnetorheological polishing, which specifically includes the following steps:

[0039] S1: Combined with the displacement sensor to obtain the ribbon data under the complete magnetorheological polishing process, and the sampling interval between adjacent sampling points is T;

[0040] S2: The data processing module calculates the magnetic streamer polishing state of the current sampling point based on the ribbon contour vectors corresponding to the adjacent ribbon data;

[0041] S3: The processing control module determines whether the magnetofluidic polishing status display at the current sampling point is normal. If so, magnetofluidic polishing is performed on the mirror surface 3 based on the current processing grinding head 1, and the magnetofluidic polishing status at the next sampling point is calculated based on steps S1-S2 until the magnetofluidic polishing is completed. Otherwise, the current processing grinding head 1 is processed, and the magnetofluidic polishing status at the next sampling point is calculated based on steps S1-S2 until the magnetofluidic polishing is completed.

[0042] In some embodiments, in step S2 , each ribbon outline vector has 1×M dimensions.

[0043] In some embodiments, in step S2, based on the ribbon contour vectors corresponding to the adjacent sampling points, the formula used to calculate the magnetic streamer polishing state of the current sampling point is:

[0044] (1);

[0045] Where i is the i-th element in the ribbon profile vector, t is the t-th second in the complete magnetorheological polishing process, E is the ribbon profile vector, is the processing speed, For tolerance, This is the ribbon outline when the polishing wheel is outside the mirror surface 3. This is the ribbon profile when the polishing wheel is in the mirror 3. is the distance between adjacent sampling points, is the element number in the ribbon profile vector corresponding to the limit point where the polishing wheel undergoes a sudden change between the outside of mirror 3 and the inside of mirror 3.

[0046] In some embodiments, at the current sampling point, when If formula (1) is satisfied, it means that the magnetorheological polishing state is normal; otherwise, it means that the magnetorheological polishing state is abnormal.

[0047] Example 1

[0048] The present invention uses a displacement sensor to collect The present invention collects data on the changes in the magnetorheological polishing ribbon 2 during the complete polishing process and records any specific normal fluctuations in the data. This facilitates eliminating these fluctuations during the next processing step. The present invention inputs real-time ribbon profile data into a real-time processing algorithm to determine the magnetorheological polishing status.

[0049] S1, collect data in the current sampling period through the displacement sensor A complete set of ribbon data for the processing flow ,in Representative The ribbon profile at the tth second under the complete processing flow.

[0050] S2. To eliminate the impact of ribbon fluctuations during normal processing on the real-time processing algorithm, the ribbon fluctuations generated during normal processing are calibrated to prevent the algorithm from misjudging the ribbon fluctuations generated during normal processing. The abnormal processing state is judged using the following formula.

[0051] Generally speaking, optical processing trajectories include grating trajectories, spiral trajectories, random trajectories, etc. Here we take two commonly used processing trajectories as examples, such as Figure 2 As shown, the grating trajectory ( Figure 2 (a)) and the spiral trajectory ( Figure 2 (b) in the figure analyzes the various normal ribbon fluctuations generated during the optical processing.

[0052] like Figure 3 As shown, when the polishing ribbon 2 does not interact with the mirror 3, the ribbon appears as follows under the action of the magnetic field. Figure 4 In the profile (a), when the effective area of ​​the ribbon is in contact with the mirror 3 and acts on the mirror 3, the effective area of ​​the ribbon is deformed due to the positive pressure between the polishing wheel and the mirror 3. At this time, the ribbon profile is as follows: Figure 4 As shown in (b) in the figure. During most of the processing time using the magnetorheological polishing equipment, the ribbon is in Figure 4 However, when the edge of the mirror 3 is processed, the effective area of ​​the ribbon is not entirely within the mirror 3 area, which will produce Figure 4 (a) to Figure 4 The intermediate state between (b).

[0053] The processing procedure of magnetorheological polishing is generally obtained by calculating the initial parameters such as the initial surface characteristics of the processed mirror and the removal function of the processing through the residence time algorithm. The residence time of the processing equipment at each control point is generally converted into the feed speed of the processing equipment between the two control points. Therefore, magnetorheological polishing is not a uniform process. However, under normal circumstances, the distribution of the feed speed does not have a particularly large variance. Here, in order to simplify the analysis, it is assumed that the polishing wheel of magnetorheological processing is within a small range of the edge area, and the speed of the ribbon entering and leaving the processing area is constant. , and the removal function forms a 90° angle with the machining trajectory.

[0054] In summary, considering the grating track and the spiral track, each time the magnetorheological polishing wheel runs along the processing track to the edge area, the ribbon behaves as follows each time it leaves the mirror surface 3. Figure 5 (a)- Figure 5 The change process of (d) in the figure is as follows. On the contrary, when the processing unit performs the mirror 3 area, the ribbon changes from Figure 5 (d)- Figure 5 The changing process of (a) in .

[0055] It should be noted that when the ribbon is in Figure 5 When the limit state shown in (a) is reached, the ribbon moves further away from the mirror 3. Due to the instantaneous release of pressure, the ribbon will suddenly change to the state shown in (a). Figure 5 The state shown in (b) in the figure. Figure 5 The state of (b) is Figure 5 The state (d) in the figure will gradually change as the processing unit moves outside the mirror 3. Similarly, when entering the mirror 3 from outside, the ribbon will gradually change from Figure 5 (d) to Figure 5 (b) in the extreme state suddenly changes to Figure 5 Therefore, the normal ribbon fluctuations in the edge area are divided into two types: one is a sudden change and the other is a slow change.

[0056] The present invention uses the L1 norm of the difference between the ribbon contour vectors collected by the displacement sensor before and after two samplings as an indicator to measure the ribbon abnormality. Sampling is performed once per second, and the ribbon contour vector obtained by each sampling is , then the indicator for measuring stability is: ;

[0057] like Figure 6 As shown, for the special case of the edge area, the ribbon outline when the entire ribbon is outside the mirror surface 3 is , the outline of the ribbon when the entire ribbon is within the mirror plane 3 is , the limit point when the mutation occurs is the first data points, and the distance between each data point is , when in the slowly changing area, the change of each sampling at this time is approximately: ;

[0058] When in the mutation region, it is approximately: ;

[0059] Therefore, when the ribbon profile does not change to these two values ​​or is not constant, it means that the magnetorheological polishing is abnormal. Assume that the system tolerance is , specifically the small fluctuations that may occur due to the vibration of the robot arm or machine tool itself: (1);

[0060] S3. After the above-mentioned normal processing fluctuations are calculated, when real-time magnetorheological polishing abnormal state monitoring is required, the ribbon contour vectors corresponding to two adjacent sampling points are used as input to obtain the processing state at that time. If the processing is abnormal, the abnormal state will be transmitted to the processing control unit, and the processing grinding head 1 will be urgently lifted and stopped to prevent the processing abnormality from affecting the final processing result.

[0061] The present invention is not limited to grating track processing and spiral track processing, and can also be used for ribbon monitoring under any other processing track, and this method can also be used to monitor the abnormal polishing state of aspheric mirrors.

[0062] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0063] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A real-time monitoring method for abnormal state of magnetorheological polishing, characterized in that: The method specifically comprises the following steps: S1: Combined with the displacement sensor to obtain the ribbon data under the complete magnetorheological polishing process, and the sampling interval between adjacent sampling points is T; S2: The data processing module calculates the magnetic streamer polishing state of the current sampling point based on the ribbon contour vectors corresponding to the adjacent ribbon data; In step S2, based on the ribbon contour vectors corresponding to the adjacent sampling points, the formula used to calculate the magnetic streamer polishing state of the current sampling point is: （1）； Where i is the i-th element in the ribbon profile vector, t is the t-th second in the complete magnetorheological polishing process, E is the ribbon profile vector, is the processing speed, For tolerance, This is the ribbon outline when the polishing wheel is outside the mirror surface. This is the ribbon outline when the polishing wheel is in the mirror surface. is the distance between adjacent sampling points, is the element number in the ribbon profile vector corresponding to the limit point where the polishing wheel undergoes a sudden change between outside the mirror surface and inside the mirror surface; S3: The processing control module determines whether the magnetofluidic polishing status display at the current sampling point is normal. If so, magnetofluidic polishing is performed on the mirror surface based on the current processing grinding head, and the magnetofluidic polishing status at the next sampling point is calculated based on steps S1-S2 until the magnetofluidic polishing is completed. Otherwise, the current processing grinding head is processed, and the magnetofluidic polishing status at the next sampling point is calculated based on steps S1-S2 until the magnetofluidic polishing is completed.

2. The real-time monitoring method for abnormal state of magnetorheological polishing according to claim 1 is characterized in that: In step S2, each ribbon outline vector is of 1×M dimensions.

3. The real-time monitoring method for abnormal state of magnetorheological polishing according to claim 1 is characterized in that: At the current sampling point, when If formula (1) is satisfied, it means that the magnetorheological polishing state is normal; otherwise, it means that the magnetorheological polishing state is abnormal.

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