Precision machining method for constant pressure rupture of rocket rupture diaphragm

Abstract

The present invention provides a precision machining method for constant pressure rupture of a rocket rupture diaphragm, comprising: step S1: measuring the original thickness of the diaphragm to be processed; step S2: fixing the diaphragm to be processed, determining the center of the diaphragm, and moving the optical axis to make it concentric with the center of the diaphragm; step S3: adjusting the focus of the laser spot and focusing on the surface of the diaphragm; based on the settings including the laser scanning path, laser power, number of scanning layers, feed amount per layer, and angular velocity of rotation of the workbench, using a femtosecond laser to complete the diaphragm notching processing; step S4: using a confocal microscope to measure the diaphragm notch and calculate the depth of the diaphragm notch; step S5: calculating the remaining thickness of the diaphragm according to the original thickness of the diaphragm and the notch depth, and retaining the diaphragm whose remaining thickness meets the preset requirements. The present invention can achieve a diaphragm rupture pressure fluctuation of no more than ±0.01MPa, solving the problem of large dispersion of diaphragm rupture pressure and low qualified rate.

Description

Technical Field

[0001] The invention relates to the technical field of laser beam processing, and in particular to a precision processing method for constant-pressure rupture of a rocket rupture diaphragm. Background Art

[0002] The rupture diaphragm is one of the key core components of the launch vehicle's booster delivery system. It is mainly used in the booster pipeline to isolate the tank from the booster cylinder before the cylinder gas is pressurized. After the rocket engine is ignited, the pressure reducing valve opens, and the upstream booster gas enters the pipeline. The diaphragm is subjected to the gas pressure gradually rising to the target pressure until it ruptures, thus achieving conduction of the booster pipeline. The accurate rupture of the diaphragm at the target pressure is the key to the normal operation of the rocket's booster delivery system. At present, the production of diaphragms usually adopts stamping and forming, and a small number of diaphragms are processed by picosecond laser. For a long time, the rupture pressure dispersion of the diaphragm has been large. Even through the optimization of process parameters, the dispersion can still reach ±0.06MPa, and constant pressure rupture cannot be achieved. The reason is that, on the one hand, the rupture pressure of the stamped diaphragm cannot be accurately controlled due to the internal stress of the stamping and the strain strengthening of the diaphragm material. On the other hand, the continuous wear of the stamping die causes the change of the equivalent radius of curvature at the bottom of the notch, which in turn causes the change of the stress concentration coefficient at the bottom of the notch, and ultimately leads to a large dispersion of the rupture pressure of the diaphragm. In the stamping method, the mechanical properties of the material at the notch position change due to strain strengthening, which has a strong uncertainty. Therefore, the rupture pressure difference of the diaphragm can only be measured through destructive tests, and there is a lack of accurate prediction methods for its performance.

[0003] Patent document CN116608774B (application number: 202310880767.7) discloses a method for detecting residual thickness of a structural part notch, a thickness detection device and a detection apparatus. The method includes: obtaining first point cloud data and second point cloud data of the structural part placed between a first laser detection unit and a second laser detection unit, the first point cloud data including data of the first surface of the structural part, the second point cloud data including data of the second surface of the structural part, at least one of the first surface of the structural part and the second surface of the structural part is provided with a notch, and the notch corresponds to a plurality of detection points; processing the first point cloud data and the second point cloud data to determine the thickness of the plurality of detection points. In this way, after the structural part is positioned once, the residual thickness detection of all detection points on the notch of the structural part can be completed, thereby improving the detection efficiency.

[0004] The lack of stability in the diaphragm rupture pressure requires a large number of random inspections for each batch of diaphragms. If one piece is out of tolerance, the entire batch must be scrapped, which is not conducive to controlling production costs and improving production efficiency. Summary of the invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a precision machining method for constant-pressure rupture of a rocket rupture diaphragm.

[0006] According to the present invention, a precision machining method for constant pressure rupture of a rocket rupture diaphragm is provided, comprising:

[0007] Step S1: measuring the original thickness of the diaphragm to be processed;

[0008] Step S2: fix the diaphragm to be processed, determine the center of the diaphragm, and move the optical axis to make it concentric with the center of the diaphragm;

[0009] Step S3: adjusting the focus of the laser spot and focusing on the surface of the membrane; based on the settings including the laser scanning path, laser power, number of scanning layers, feed amount per layer and angular velocity of the worktable, using a femtosecond laser to complete the membrane scoring process;

[0010] Step S4: using a confocal microscope to measure the film score and calculate the depth of the film score;

[0011] Step S5: Calculate the remaining thickness of the diaphragm according to the original thickness of the diaphragm and the notch depth, and retain the diaphragms whose remaining thickness meets the preset requirements.

[0012] Preferably, the step S4 adopts:

[0013] Step S4.1: using confocal microscopy to measure the scratches on the ruptured membrane to obtain three-dimensional point cloud data of the scratches;

[0014] Step S4.2: According to the x, y, z coordinates of the notch three-dimensional point cloud data, a least square method is used to perform plane fitting processing on the notch three-dimensional point cloud data to obtain a reference plane;

[0015] Step S4.3: using the reference plane to perform plane calibration on the three-dimensional point cloud data of the notch to obtain the three-dimensional point cloud data after plane calibration;

[0016] Step S4.4: performing statistical analysis on the height coordinate information of the calibrated three-dimensional point cloud data to obtain a bimodal distribution histogram of the data;

[0017] Step S4.5: using the statistical averaging method to calculate the average heights of the two wave peaks respectively;

[0018] Step S4.6: Calculate the difference between the average values ​​of the double peak heights to obtain the effective depth of the membrane notch.

[0019] Preferably, the step S1 comprises: measuring the original thickness of the diaphragm using a contact measuring instrument or a lever micrometer;

[0020] The measuring positions are multiple positions evenly distributed on the circumference of the diaphragm notch, and the original thickness of the diaphragm is determined according to the average thickness of the multiple positions.

[0021] Preferably, the step S2 comprises: fixing the diaphragm on a clamping device;

[0022] The clamping device comprises: a rotating workbench and a negative pressure adsorption device; the negative pressure adsorption device is installed on the rotating workbench; the negative pressure adsorption device is concentrically arranged with the rotating workbench and relatively fixed;

[0023] The negative pressure adsorption device is provided with a boss around it, which is used for horizontal positioning of the diaphragm;

[0024] The membrane is placed on the negative pressure adsorption device, the vacuum pump is turned on, and the membrane is adsorbed and fixed by negative pressure.

[0025] Preferably, the step S2 adopts: using a laser axis bypass camera to identify the edge of the diaphragm and determine the center of the diaphragm.

[0026] Preferably, the step S3 adopts: the femtosecond laser beam reaches the center of the field lens after passing through the X scanning galvanometer and the Y scanning galvanometer, and reaches the surface of the diaphragm after being focused by the field lens.

[0027] Preferably, the step S3 adopts: focusing the laser spot on the upper surface of the diaphragm, and during the processing, controlling the X-scanning galvanometer and the Y-scanning galvanometer to realize a small back-and-forth swing of the spot in the radial direction of the diaphragm to process a groove of a preset width, and using a rotating worktable to realize the circular motion of the diaphragm relative to the laser spot; through the effective cooperation of the X-scanning galvanometer and the Y-scanning galvanometer with the rotating worktable, the processing of a complete C-shaped groove is realized.

[0028] Preferably, the step S3 adopts: setting the scoring pattern to be processed according to the scoring design drawing, selecting a light spot with a diameter of 30um, setting the repetition frequency to 200kHz, setting the laser power to 3.0-3.5W, and using a galvanometer to realize the swing scanning of the light spot along the radial direction of the diaphragm to realize the scoring width processing, and setting the light spot scanning speed to 270-400mm / s; using the workbench rotation to realize the processing in the circumferential direction of the scoring, and the workbench rotation speed to 200-280° / s; setting the number of scanning layers to 51-61 layers according to the original thickness of the diaphragm, and setting the feed amount of each layer to 13-15um.

[0029] Preferably, the step S4 adopts: in the process of measuring the notch of the ruptured membrane using confocal microscopy, the measuring position is within a preset range of the intersection of the C-shaped notch of the membrane and the symmetry axis of the membrane.

[0030] Preferably, the step S5 adopts: calculating the remaining thickness of the membrane according to the original thickness of the membrane and the notch depth, and retaining the membrane with a remaining thickness of 196um to 214um.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention uses a femtosecond laser to process the diaphragm notch. There is no processing internal stress and heat-affected zone at the notch position, and the mechanical properties of the substrate are not affected, so that the working performance of the diaphragm depends only on the material's own properties and the remaining thickness of the diaphragm. Through the selection of raw materials and the combination of reasonable processing parameters, notches of a specific depth can be processed, thereby achieving the rupture of the diaphragm near the set pressure value;

[0033] 2. The 1 mm aluminum alloy diaphragm processed by the method provided by the present invention can achieve a rupture pressure deviation of no more than ±0.01 MPa;

[0034] 3. The present invention obtains millions of large-scale measurement point cloud data including the size of the diaphragm scratches and the surface morphology characteristics through high-precision confocal microscopy measurement of the key positions of the rocket ruptured diaphragm. By processing and analyzing the point cloud data, the effective depth characteristics of the scratches are extracted from the large-scale point cloud, realizing the accurate prediction of the diaphragm performance based on the effective depth of the scratches.

[0035] 4. The diaphragm notch depth determination method proposed in the present invention can accurately measure the diaphragm notch depth, solving the problem that the traditional measurement method cannot determine the accurate depth of the diaphragm, and the performance of the diaphragm can be accurately calculated based on the measurement results;

[0036] 5. The present invention obtains millions of large-scale measurement point cloud data including the size of the diaphragm scratches and the surface morphology characteristics through high-precision confocal microscopy measurement of the key positions of the rocket ruptured diaphragm. By processing and analyzing the point cloud data, the effective depth characteristics of the scratches are extracted from the large-scale point cloud, realizing the accurate prediction of the diaphragm performance based on the effective depth of the scratches.

[0037] 6. The diaphragm notch depth determination method proposed in the present invention can accurately measure the diaphragm notch depth, solving the problem that the traditional measurement method cannot determine the accurate depth of the diaphragm, and the performance of the diaphragm can be accurately calculated based on the measurement results. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0039] Figure 1 This is the schematic diagram of femtosecond laser processing of diaphragm.

[0040] Figure 2It is a top view of the rupture disc involved in the present invention.

[0041] Figure 3 This is a cross-sectional view of the diaphragm notch structure.

[0042] Figure 4 Schematic diagram of the statistical results of the confocal measurement point cloud data of the notch.

[0043] Figure 5 Statistical histogram of the point cloud data at the bottom of the notch.

[0044] Figure 6 Statistical histogram of the notch top point cloud data.

[0045] Figure 7 This is a graph showing the relationship between the effective notch depth of the diaphragm and the diaphragm rupture pressure difference.

[0046] Among them, 1-femtosecond laser beam; 2-X scanning galvanometer; 3-Y scanning galvanometer; 4-field mirror; 5-diaphragm; 6-notch; 7-negative pressure adsorption device; 8-rotating workbench. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0048] Example 1: Figure 1 As shown, a precision machining method for constant pressure rupture of a rocket rupture diaphragm provided by the present invention comprises:

[0049] Steps for measuring the overall thickness of the diaphragm: Use precision measuring instruments such as contact measuring instruments and lever micrometers to measure the original thickness of the diaphragm.

[0050] Clamping and positioning steps: Place the circular diaphragm raw material to be processed on a special negative pressure adsorption clamping fixture, use the laser axis bypass camera to identify the edge of the diaphragm and determine the center of the circle. Move the optical axis to make it concentric with the center of the diaphragm.

[0051] Laser processing steps: After the film is clamped and positioned, adjust the focus of the laser spot and focus on the film surface. Set the laser scanning path, laser power, number of scanning layers, feed amount per layer, angular velocity of the worktable and other parameters, and use femtosecond laser to complete the film scoring process.

[0052] Membrane scratch depth measurement steps: Use a confocal microscope to measure the membrane scratch and calculate the depth of the membrane scratch.

[0053] Diaphragm screening steps: Calculate the remaining thickness of the diaphragm based on the original thickness and the depth of the notch, remove diaphragms with surface scratches and excess remaining thickness, and retain diaphragms with remaining thickness within the required range.

[0054] In this embodiment, the femtosecond laser beam 1 reaches the center of the field lens 4 after passing through the X-scanning galvanometer 2 and the Y-scanning galvanometer 3, and reaches the surface of the diaphragm 5 to be processed after being focused by the field lens 4. The laser spot is focused on the upper surface of the diaphragm 5. During the processing, the X-scanning galvanometer 2 and the Y-scanning galvanometer 3 are controlled to realize a small reciprocating swing of the spot in the radial direction of the diaphragm to process a groove of a specific width. At the same time, the rotary table 8 is used to rotate to realize the circular motion of the diaphragm 5 relative to the laser spot. Through the effective cooperation of the X-scanning galvanometer 2, the Y-scanning galvanometer 3 and the rotary table 8, the processing of the complete C-shaped groove 6 is realized. During the processing, the laser beam always moves in the central area of ​​the field lens 4, the spatial distortion of the spot is small, and the processing shape control ability is strong. At the same time, the negative pressure adsorption device 7 is used to firmly adsorb the diaphragm 5 on the surface of the negative pressure adsorption device 7, which increases the flatness of the diaphragm 5, eliminates the deformation of traditional mechanical clamping, and further improves the processing accuracy.

[0055] The specific implementation is as follows:

[0056] The overall thickness measurement step of the diaphragm is as follows: the original thickness of the diaphragm is measured using a contact measuring instrument, a lever micrometer or other precision measuring instrument. The measuring positions are four positions evenly distributed on the circumference of the diaphragm notch, and the original thickness of the diaphragm is determined based on the average value of the four positions, and the thickness should meet 1.0±0.02mm.

[0057] The clamping and positioning steps are as follows: Place the circular diaphragm raw material to be processed on a special negative pressure adsorption clamping tool, use a laser axis bypass camera to identify the edge of the diaphragm, and determine the center of the circle. Move the optical axis so that it is concentric with the center of the diaphragm. The clamping device includes a rotating worktable at the bottom and a negative pressure adsorption device at the top, which are concentrically arranged and relatively fixed. There are bosses around the negative pressure adsorption device for horizontal positioning of the circular diaphragm. Place the diaphragm on the negative pressure adsorption device and identify the center of the circle, turn on the vacuum pump, and maintain the gauge pressure at -0.1MPa. Use negative pressure to adsorb and fix the diaphragm. Use a bypass camera to identify the outer circle of the negative pressure adsorption device and calculate the center of the circle, and move the laser spindle so that it is concentric with the diaphragm.

[0058] The laser processing steps are as follows: After the diaphragm is clamped and positioned, adjust the focus of the femtosecond laser spot and focus on the surface of the diaphragm. Set the pattern of the notch to be processed according to the notch design drawing, select a laser spot with a diameter of 30um, set the repetition frequency to 200kHz, set the laser power to 3.0-3.5W, and use a galvanometer to realize the radial swing scanning of the spot along the diaphragm to realize the notch width processing, and set the spot scanning speed to 270-400mm / s. Use the workbench rotation to realize the processing in the circumferential direction of the notch, and the workbench rotation speed is 200-280° / s. Set the number of scanning layers to 51-61 layers according to the original thickness of the diaphragm, and set the feed amount per layer to 13-15um. The spot scanning is coordinated with the workbench rotation to realize the complete C-shaped notch processing until the given number of processing layers is processed to complete the final processing of the diaphragm.

[0059] The step of measuring the depth of the membrane notch is as follows: using a confocal microscope to measure the depth of the membrane notch, and the measurement position is selected near the highest point of the C-shaped notch, such as Figure 2 The position of the section line is shown in FIG. 1 , where AA indicates that a local section plane is drawn at this position. The resulting local section view is shown in FIG. Figure 3 As shown. The depth of the membrane scratch is calculated based on the confocal measurement of the active point cloud data. Specifically, the scratches of the ruptured membrane are measured using confocal microscopy to obtain the three-dimensional point cloud data of the scratches; based on the x, y, and z coordinates of the three-dimensional point cloud data of the scratches, the least squares method is used to perform plane fitting processing on the three-dimensional point cloud data of the scratches to obtain a reference plane; the reference plane is used to perform plane calibration on the three-dimensional point cloud data of the scratches to obtain the three-dimensional point cloud data after plane calibration; that is, based on the x and y coordinates of the three-dimensional point cloud of the scratches, the reference plane equation is used to calculate the z coordinate of the (x, y) point on the reference plane, and the z coordinate of the corresponding position on the reference plane is subtracted from the z coordinate of the three-dimensional point cloud of the scratches to obtain the three-dimensional point cloud data after plane calibration. The height coordinate information of the calibrated three-dimensional point cloud data is statistically analyzed to obtain a bimodal distribution histogram of the data, as shown in Figure 4 As shown; specifically, the number and range of histogram columns are determined according to the maximum and minimum values ​​of the point cloud z coordinates and the width of a single column interval;

[0060] No. The interval corresponding to the root column is:

[0061]

[0062] in, Indicates the column interval width;

[0063] Count the z coordinates that fall in each interval The number of point clouds in each interval is calculated, the average z coordinate of the point cloud in each interval is calculated, and a histogram is drawn;

[0064] The average z-coordinate in each interval is:

[0065]

[0066] like Figure 5 As shown, the data with z coordinates less than the average depth of the notch in the histogram are regarded as the smaller part of the data, and the distribution of the smaller part of the data is arranged in descending order to obtain a list of point cloud data in each interval from high to low; based on the current arrangement list, the first n elements in the list are obtained, L1, L2, ..., Ln; based on L1, L2, ..., Ln, the bottom peak of the notch is constructed;

[0067] like Figure 6 As shown, the data whose z coordinate in the histogram is greater than the average depth of the notch is regarded as the larger part of the data, and the distribution of the larger part of the data is arranged in descending order to obtain a list of point cloud data in each interval from high to low; based on the current arrangement list, the first n elements H1, H2, ..., Hn in the list are obtained; based on H1, H2, ..., Hn, the peak at the top of the notch is constructed.

[0068] The statistical averaging method was used to calculate the average height of the two peak positions.

[0069] Specifically, after obtaining the average height of all point clouds in L1, use the average height as the effective height of the bottom plane of the notch; when the difference between the number of point clouds in L1 and L2 is less than a preset value, calculate the average height of all point cloud data in L1 and L2, and use the average height as the effective height of the bottom plane of the notch; when the difference between the number of point clouds in L1 and L2 is less than a preset value, and the difference between the number of point clouds in L2 and L3 is less than a preset value, calculate the average height of all point cloud data in L1, L2 and L3, and use the average height as the effective height of the bottom plane of the notch; and so on to Ln; wherein, ;

[0070] After obtaining the average height of all point clouds in H1, use this average as the effective height of the top plane of the notch; when the difference in the number of point clouds in H1 and H2 is less than the preset value, calculate the average height of all point cloud data in H1 and H2, and use this average as the effective height of the top plane of the notch. When the difference in the number of point clouds in H1 and H2 is less than the preset value, and the difference in the number of point clouds in H2 and H3 is less than the preset value, calculate the average height of all point cloud data in H1, H2 and H3, and use this average as the effective height of the top plane of the notch. Figure 7 The relationship between the effective depth of 11 diaphragms and the rupture pressure difference is given, and the correlation coefficient (absolute value) reaches 0.9991, which shows that the notch effective depth measurement method proposed in the present invention is reasonable and can reflect the change of the diaphragm rupture pressure difference.

[0071] The difference between the average values ​​of the double peak heights was calculated to obtain the effective depth of the film notch.

[0072] The diaphragm screening step is to check whether the diaphragm surface is scratched or not. If so, it is considered as an unqualified diaphragm and is discarded. Then, the residual thickness d of the diaphragm is obtained by subtracting the scratch depth from the measured original thickness of the diaphragm, as shown in Figure 3 As shown, the membranes with a residual thickness d between 196um and 214um are considered qualified, can be accurately ruptured, and have a small dispersion, and the rest are discarded.

[0073] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0074] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A precision machining method for constant pressure rupture of a rocket rupture diaphragm, characterized in that: include: Step S1: measuring the original thickness of the diaphragm to be processed; Step S2: fix the diaphragm to be processed, determine the center of the diaphragm, and move the optical axis to make it concentric with the center of the diaphragm; Step S3: adjusting the focus of the laser spot and focusing on the surface of the membrane; based on the settings including the laser scanning path, laser power, number of scanning layers, feed amount per layer and angular velocity of the worktable, using a femtosecond laser to complete the membrane scoring process; Step S4: using a confocal microscope to measure the film score and calculate the depth of the film score; Step S5: calculating the remaining thickness of the membrane according to the original thickness of the membrane and the notch depth, and retaining the membrane whose remaining thickness meets the preset requirements; The step S4 adopts: Step S4.1: using confocal microscopy to measure the scratches on the ruptured membrane to obtain three-dimensional point cloud data of the scratches; Step S4.2: According to the x, y, z coordinates of the notch three-dimensional point cloud data, a least square method is used to perform plane fitting processing on the notch three-dimensional point cloud data to obtain a reference plane; Step S4.3: using the reference plane to perform plane calibration on the three-dimensional point cloud data of the notch to obtain the three-dimensional point cloud data after plane calibration; Step S4.4: performing statistical analysis on the height coordinate information of the calibrated three-dimensional point cloud data to obtain a bimodal distribution histogram of the data; Step S4.5: using the statistical averaging method to calculate the average heights of the two wave peaks respectively; Step S4.6: Calculate the difference between the average values ​​of the double peak heights to obtain the effective depth of the film notch; The step S1 comprises: measuring the original thickness of the diaphragm using a contact measuring instrument and a lever micrometer; The measuring positions are multiple positions evenly distributed on the circumference of the diaphragm notch, and the original thickness of the diaphragm is determined according to the average thickness of the multiple positions; The step S4.5 comprises: The data whose z coordinate in the histogram is less than the average depth of the notch is regarded as a smaller part of the data, and the distribution of the smaller part of the data is arranged in descending order to obtain a permutation list of the point cloud data of each interval from high to low; based on the current permutation list, the first n elements in the list are obtained, L1, L2, ..., Ln; based on L1, L2, ..., Ln, the bottom peak of the notch is constructed; The data with z coordinates greater than the average depth of the notch in the histogram are regarded as the larger part of the data, and the distribution of the larger part of the data is arranged in descending order to obtain a list of point cloud data in each interval from high to low; based on the current arrangement list, the first n elements H1, H2, ..., Hn in the list are obtained; based on H1, H2, ..., Hn, the peak of the notch top is constructed; After obtaining the average height of all point clouds in L1, use the average height as the effective height of the bottom plane of the notch; when the difference between the number of point clouds in L1 and L2 is less than the preset value, calculate the average height of all point cloud data in L1 and L2, and use the average height as the effective height of the bottom plane of the notch; when the difference between the number of point clouds in L1 and L2 is less than the preset value, and the difference between the number of point clouds in L2 and L3 is less than the preset value, calculate the average height of all point cloud data in L1, L2 and L3, and use the average height as the effective height of the bottom plane of the notch; and so on to Ln; where, ; After obtaining the average height of all point clouds in H1, use the average height as the effective height of the top plane of the notch; when the difference in the number of point clouds in H1 and H2 is less than a preset value, calculate the average height of all point cloud data in H1 and H2, and use the average height as the effective height of the top plane of the notch; when the difference in the number of point clouds in H1 and H2 is less than a preset value, and the difference in the number of point clouds in H2 and H3 is less than a preset value, calculate the average height of all point cloud data in H1, H2 and H3, and use the average height as the effective height of the top plane of the notch.

2. The precision machining method for constant pressure rupture of rocket rupture diaphragm according to claim 1 is characterized in that: The step S2 comprises: fixing the diaphragm on a clamping device; The clamping device comprises: a rotating workbench and a negative pressure adsorption device; the negative pressure adsorption device is installed on the rotating workbench; the negative pressure adsorption device is concentrically arranged with the rotating workbench and relatively fixed; The negative pressure adsorption device is provided with a boss around it, which is used for horizontal positioning of the diaphragm; The membrane is placed on the negative pressure adsorption device, the vacuum pump is turned on, and the membrane is adsorbed and fixed by negative pressure.

3. The precision machining method for constant pressure rupture of rocket rupture diaphragm according to claim 1 is characterized in that: The step S2 adopts: using a laser axis bypass camera to identify the edge of the diaphragm and determine the center of the diaphragm.

4. The precision machining method for constant pressure rupture of rocket rupture diaphragm according to claim 1 is characterized in that: The step S3 adopts: the femtosecond laser beam reaches the center of the field lens after passing through the X scanning galvanometer and the Y scanning galvanometer, and reaches the surface of the diaphragm after being focused by the field lens.

5. The method for precision machining of rocket rupture diaphragm constant pressure rupture according to claim 4, characterized in that: The step S3 adopts: focusing the laser spot on the upper surface of the diaphragm, and during the processing, controlling the X-scanning galvanometer and the Y-scanning galvanometer to realize a small back-and-forth swing of the spot in the radial direction of the diaphragm to process a groove of a preset width, and using a rotating worktable to realize the circular motion of the diaphragm relative to the laser spot; through the effective cooperation of the X-scanning galvanometer and the Y-scanning galvanometer and the rotating worktable, the processing of a complete C-shaped groove is realized.

6. The method for precision machining of rocket rupture diaphragm constant pressure rupture according to claim 5, characterized in that: The step S3 adopts: setting the scoring pattern to be processed according to the scoring design drawing, selecting a light spot with a diameter of 30um, setting the repetition frequency to 200kHz, setting the laser power to 3.0-3.5W, using a galvanometer to realize the swing scanning of the light spot along the radial direction of the diaphragm to realize the scoring width processing, and setting the light spot scanning speed to 270-400mm / s; using the workbench rotation to realize the processing in the circumferential direction of the scoring, the workbench rotation speed is 200-280° / s; setting the number of scanning layers to 51-61 layers according to the original thickness of the diaphragm, and setting the feed amount of each layer to 13-15um.

7. The precision machining method for constant pressure rupture of rocket rupture diaphragm according to claim 1 is characterized in that: The step S4 adopts: in the process of measuring the score of the ruptured membrane using confocal microscopy, the measuring position is within a preset range of the intersection of the C-shaped score of the membrane and the symmetry axis of the membrane.

8. The method for precision machining of rocket rupture diaphragm constant pressure rupture according to claim 1, characterized in that: The step S5 adopts: calculating the remaining thickness of the membrane according to the original thickness of the membrane and the notch depth, and retaining the membrane with a remaining thickness of 196um to 214um.

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