A method for determining the reliability of a nut device separating a bolt capture

Abstract

The application is a kind of reliable capture judgment method for butt joint bolt of separated nut device, first, the quantitative relationship between axial extrusion stroke and flying speed of butt joint bolt is obtained by theoretical calculation, then the flying speed range of butt joint bolt in ground test is counted, and the corresponding axial stroke of butt joint bolt under various working conditions is obtained by substituting the relationship. Then, the process of butt joint bolt flying is restored by pneumatic test, and whether it is captured reliably is determined by comparing and analyzing the quantitative results after the test. The application realizes the innovation of positive optimization design of key design index, helps the core function of pyrotechnic separation device to be checked and measured, releases the risk of pyrotechnic separation nut device in flight test in advance, solves the reliability index verification problem of pyrotechnic separation device in aerospace field, and ensures the success of launch task.

Description

Technical Field

[0001] This invention relates to a method for determining the reliability of bolt capture in a separation nut device, belonging to the technical fields of structural design of launch vehicle pyrotechnic separation devices and reliability testing of aerospace products. Background Technology

[0002] Low-impact separation nut devices are widely used in processes such as upper stage separation of launch vehicles, grid wing unlocking of escape systems, head and body separation of spacecraft, and star-rocket unlocking and separation. The device achieves connection and unlocking through the threaded engagement between the separation nut assembly and the docking bolt. A capture device assembly is set on one side of the head of the docking bolt to capture the docking bolt after separation.

[0003] The nut release device capture mechanism employs a conical hole compression capture structure with a single-sided cone angle of 6°. Schematic diagrams of the device in both the connection and capture states are shown below. Figure 1 When the device is in operation, high-pressure gas supplied by pyrotechnic devices such as igniters causes the separating nut to open radially and release the connecting bolt. Simultaneously, the gas pushes the connecting bolt out, which then enters the catcher and locks into place within the conical section at the top of the catcher housing. The catch function is one of the core functions of the entire separating nut device, making the research on testing and evaluation methods for its reliability crucial. Current technologies lack methods for testing and evaluating the catch performance of separating nut devices, thus making it impossible to effectively determine the product's catch reliability before flight testing, resulting in a situation where functional products are neither testable nor verifiable. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a method for determining the reliability of the bolt capture of the separating nut device, which solves the problem of verifying the reliability index of pyrotechnic separation devices in the aerospace field and ensures the success of launch missions.

[0005] The technical solution of this invention is: a method for determining the reliability of bolt capture in a nut separation device, comprising:

[0006] Establish the relationship between the axial travel of the connecting bolt as it is pressed into the tapered hole of the catcher housing and the speed of the connecting bolt;

[0007] Ground tests were conducted on the separating nut device to obtain the speed range of the connecting bolt after ignition; based on the established relationship between the axial travel of the connecting bolt extruding into the cone hole of the catcher housing and the speed of the connecting bolt, the range of axial travel of the connecting bolt extruding into the catcher housing at different speeds was obtained.

[0008] The axial travel of the connecting bolts at different speeds was measured by pneumatic testing, and compared with the axial travel range of the connecting bolts being squeezed into the capture housing at different speeds to determine the reliability of the product.

[0009] The relationship between the axial travel of the connecting bolt as it is pressed into the tapered hole of the catcher housing and the speed of the connecting bolt is as follows:

[0010]

[0011] Where d is the axial stroke of the butt bolt pressing the shell, m is the mass of the butt bolt, D is the outer diameter of the bolt head, θ is the cone angle of the shell, E is the elastic modulus of the shell, h is the wall thickness of the shell, l is the length of the pressing ring between the shell and the bolt head, u is the coefficient of friction, and v is the speed of the butt bolt.

[0012] The separating nut device uses two redundant igniters with internal explosive charges as input energy. Through ground tests with different charge amounts, the performance data of the separating nut device within the envelope of the maximum and minimum charge amounts are obtained, corresponding to the speed range of the connecting bolt after ignition. Using the recorded speed range, the axial travel range of the connecting bolt pressing into the cone hole of the trap housing at different speeds is calculated based on the relationship between the axial travel of the connecting bolt pressing into the trap housing and the speed of the connecting bolt.

[0013] The measured values ​​of the axial travel of the connecting bolts at different speeds are tested using pneumatic testing, and compared with the axial travel range of the connecting bolts being squeezed into the capture device housing at different speeds to determine product reliability, including:

[0014] 31) Select N samples of the same specification from the formal products;

[0015] 32) Simulate different ejection speeds of the docking bolts, and record the entire process from ejection to capture using sensors or high-speed photography; statistically analyze the capture success rate of the docking bolts, and measure the height of the docking bolts from the top of the capture device to calculate the measured axial travel value of the docking bolts being squeezed into the capture device housing.

[0016] 33) Compare the measured values ​​with the calculated axial travel range of the bolts being squeezed into the capture housing at different speeds. If the values ​​are within the range, and all samples can be captured and the corresponding measured axial travel values ​​are not less than the minimum axial travel range of the bolts being squeezed into the capture housing at different speeds, then the capture is considered reliable.

[0017] 34) If there is an uncaptured sample or the measured value of axial travel is less than the minimum value of the axial travel range of the butt bolt pressing into the capture housing at different speeds, then add an extra sample and make the axial travel range of the butt bolt pressing into the capture housing at different speeds M times the original value, and repeat step 33). If all samples can be captured and the corresponding measured value of axial travel is not less than the minimum value of the axial travel range of the butt bolt pressing into the capture housing at different speeds after M times, then the capture is considered reliable; otherwise, the capture is considered unreliable.

[0018] The number of samples N is not less than 3.

[0019] The value of M is 1.5.

[0020] Light bubbles were used to simulate the different ejection speeds of the bolts.

[0021] Each sub-sample includes a mating bolt, a catcher base, and a catcher housing, ensuring that the product installation meets design requirements.

[0022] The advantages of this invention compared to the prior art are:

[0023] (1) The core functions of the nut separation device include bearing, separation and capture. The structural design parameters of the product usually depend on the two functions of bearing and separation. This invention establishes a test and evaluation method for capture reliability, verifies the influence of design parameters such as bolt head outer diameter, capture device housing wall thickness, and housing cone angle on capture reliability, and achieves innovation in the positive optimization design of key design indicators.

[0024] (2) Through theoretical derivation, the formula for the proportional relationship between the axial travel of the connecting bolt and the flight speed is obtained. Based on the experimental test data, this invention obtains the quantitative index envelope range representing the capture process, and realizes the innovation in the capture reliability test and evaluation method.

[0025] (3) The nut separation device uses pyrotechnics as the separation power source. Due to the inherent characteristics of pyrotechnics, they usually do not have detectable properties. This invention effectively releases the risk of pyrotechnic products by pneumatically capturing and restoring the pyrotechnic separation and capture process, and realizes the innovation of the core function of the pyrotechnic separation device in terms of detectability and measurability. Attached Figure Description

[0026] Figure 1 This diagram illustrates the connection and capture states of the nut release device. a) – Connection state, b) – Capture state.

[0027] Figure 2 This diagram illustrates the expansion and deformation of the housing due to the pressure exerted by the connecting bolts.

[0028] Figure 3This is a schematic diagram of a dual-igniter cluster igniter (in a single-igniter configuration, only one igniter is activated). Detailed Implementation

[0029] This invention provides a method for determining the reliability of bolt capture in a nut-separating device, comprising:

[0030] Establish the relationship between the axial travel of the connecting bolt as it is pressed into the tapered hole of the catcher housing and the speed of the connecting bolt;

[0031] Ground tests were conducted on the separating nut device to obtain the speed range of the connecting bolt after ignition; based on the established relationship between the axial travel of the connecting bolt extruding into the cone hole of the catcher housing and the speed of the connecting bolt, the range of axial travel of the connecting bolt extruding into the catcher housing at different speeds was obtained.

[0032] The axial travel of the connecting bolts at different speeds was measured by pneumatic testing, and compared with the axial travel range of the connecting bolts being squeezed into the capture housing at different speeds to determine the reliability of the product.

[0033] The relationship between the axial travel of the connecting bolt as it is pressed into the tapered hole of the catcher housing and the speed of the connecting bolt is as follows:

[0034]

[0035] Where d is the axial stroke of the butt bolt pressing the shell, m is the mass of the butt bolt, D is the outer diameter of the bolt head, θ is the cone angle of the shell, E is the elastic modulus of the shell, h is the wall thickness of the shell, l is the length of the pressing ring between the shell and the bolt head, u is the coefficient of friction, and v is the speed of the butt bolt.

[0036] The separating nut device uses two redundant igniters with internal explosive charges as input energy. Through ground tests with different charge amounts, the performance data of the separating nut device within the envelope of the maximum and minimum charge amounts are obtained, corresponding to the speed range of the connecting bolt after ignition. Using the recorded speed range, the axial travel range of the connecting bolt pressing into the cone hole of the trap housing at different speeds is calculated based on the relationship between the axial travel of the connecting bolt pressing into the trap housing and the speed of the connecting bolt.

[0037] The measured values ​​of the axial travel of the connecting bolts at different speeds are tested using pneumatic testing, and compared with the axial travel range of the connecting bolts being squeezed into the capture device housing at different speeds to determine product reliability, including:

[0038] 31) Select N samples of the same specification from the formal products;

[0039] 32) Simulate different ejection speeds of the docking bolts, and record the entire process from ejection to capture using sensors or high-speed photography; statistically analyze the capture success rate of the docking bolts, and measure the height of the docking bolts from the top of the capture device to calculate the measured axial travel value of the docking bolts being squeezed into the capture device housing.

[0040] 33) Compare the measured values ​​with the calculated axial travel range of the bolts being squeezed into the capture housing at different speeds. If the values ​​are within the range, and all samples can be captured and the corresponding measured axial travel values ​​are not less than the minimum axial travel range of the bolts being squeezed into the capture housing at different speeds, then the capture is considered reliable.

[0041] 34) If there is an uncaptured sample or the measured value of axial travel is less than the minimum value of the axial travel range of the butt bolt pressing into the capture housing at different speeds, then add an extra sample and make the axial travel range of the butt bolt pressing into the capture housing at different speeds M times the original value, and repeat step 33). If all samples can be captured and the corresponding measured value of axial travel is not less than the minimum value of the axial travel range of the butt bolt pressing into the capture housing at different speeds after M times, then the capture is considered reliable; otherwise, the capture is considered unreliable.

[0042] A schematic diagram of the installation state of the nut release device involved in this invention is shown below. Figure 1 (a) In the installed state, the three-lobed nut at the separating nut end assembles into a complete internal thread, achieving a threaded connection with the external thread of the mating bolt, and a pre-tightening installation torque is applied. When the separating nut device is working, two redundant igniters output detonation energy, generating a large amount of gas that radially opens the three-lobed nut, unlocking the mating bolt and providing the initial ejection velocity for the bolt. During bolt ejection, it overcomes frictional resistance and the deformation energy of the trap housing, ultimately being squeezed into the conical section of the housing, achieving capture. The product state after capture is shown in the image. Figure 1 (b) In the method of this invention, the quantitative relationship between the axial travel and the ejection velocity of the connecting bolt is first obtained through theoretical calculation. Then, the ejection velocity range of the connecting bolt in the ground test is statistically analyzed, and the axial travel of the connecting bolt under various working conditions is obtained by substituting it into the relationship. Afterwards, the ejection process of the connecting bolt is reconstructed through pneumatic testing, and the quantitative results after the test are compared and analyzed to determine whether the capture is reliable. The specific implementation method for the reliability test and evaluation of the connecting bolt capture of the separating nut device is as follows.

[0043] 1. Analysis of the extrusion deformation process of the conical hole

[0044] The process of the bolt being forced into the trap cone shell is the kinetic energy of the bolt. E, converted into the elastic deformation energy of the shell nand frictional resistance work E f The sum, the energy equation is as follows:

[0045]

[0046] Assuming the axial travel of the bolt pressing against the housing is d, the deformation process of the catcher is illustrated in the attached diagram. Figure 2 As shown, based on the geometric deformation relationship, the expansion of the shell radius is:

[0047] ΔR=dsinθ (2)

[0048] Where θ is the 6° cone angle of the shell.

[0049] The shell expansion deformation energy is:

[0050]

[0051] in,

[0052] D: outer diameter of the bolt head;

[0053] E: Elastic modulus of the shell;

[0054] h: wall thickness of the shell;

[0055] l: Length of the compression ring between the housing and the bolt head

[0056] The work done by frictional resistance is:

[0057]

[0058] in,

[0059] u: coefficient of friction.

[0060] According to formulas (2), (3), and (4), the relationship between frictional resistance work and elastic deformation energy can be obtained as follows:

[0061] E f / E n =u / (sinθcos 2 θ)

[0062] Substituting θ = 6° and the coefficient of friction u = 0.12, we can obtain that the work done by frictional resistance is 1.16 times that of elastic deformation energy, and the proportion of work done by frictional resistance is larger.

[0063] Substituting formulas (2), (3), and (4) into formula (1), we get:

[0064]

[0065] That is, to obtain the proportional relationship between the axial movement stroke of the mating bolt and the speed of the mating bolt.

[0066] 2. Ignition test and capture performance test

[0067] The nut-separating device uses two redundant igniters as input energy. Ground tests were conducted to assess ignition performance under various conditions, including single igniter design charge, dual igniter design charge, single igniter small charge, and dual igniter large charge. The dual igniter cluster configuration is shown in the attached figure. Figure 3 As shown, a single igniter ignites only one end. The process of capturing the mating bolt is recorded by deploying sensors and high-speed photography along the ignition channel, and data such as the bolt speed and distance from the top after capture are measured. See Table 1 for details.

[0068] Table 1. Data on the capture performance of the nut release device after ignition test.

[0069]

[0070] Data obtained from ignition tests can be used to acquire performance data of the separating nut device within the envelope of maximum and minimum charge amounts, corresponding to the velocity range of the mating bolts after ignition. By recording the velocity range, the theoretical range of axial travel of the mating bolts as they are forced into the trap housing at different speeds can be calculated.

[0071] 3. Capture baseline test at different speeds

[0072] The data collected in Table 1 were filtered and organized to clarify the velocity distribution law of the docking bolt under different input energy conditions. The capture velocity of the docking bolt during actual flight was obtained by taking a safety factor (f = 1.5).

[0073] Products of the same specifications (sample size usually not less than 3) were selected, and a light air gun was used to conduct preliminary tests on the capture performance of the nut-separating device's capture device at different bolt speeds. Two rounds of preliminary capture tests were conducted for each test piece, one with speed decreasing and the other with speed increasing. The speed increment was typically 1 m / s. Sensors and high-speed photography were also installed on the pneumatic capture channel to record the entire capture process. The bolt speed, distance from the top, and capture success rate were measured. Finally, the reliability of the nut-separating device's capture capability was verified through testing and evaluation.

[0074] After the test, the capture success rate of the connecting bolts was statistically analyzed, and the height of the connecting bolts from the top of the capture device was measured. The axial stroke of the connecting bolts being squeezed into the capture device housing was then calculated. The measured values ​​were compared with the calculated range. If all samples were captured within the statistically specified speed range and the corresponding stroke was not less than the theoretical minimum, the capture was deemed reliable. Conversely, if any samples were not captured or the measured stroke was less than the theoretical minimum, additional samples were required. Using a safety factor of 1.5, the corresponding pneumatic simulation connecting bolt speed range was further expanded, and supplementary verification tests on capture reliability were conducted until all samples passed, at which point the capture was deemed reliable.

[0075] Typical Case

[0076] 1) Through ground tests with different charge amounts, the measured velocity of the single-point ignition butt bolts was statistically obtained to be 2.67 m / s to 3.87 m / s, and the measured velocity of the double-point synchronous ignition butt bolts was 3.97 m / s to 4.69 m / s. That is, the statistical velocity range of the butt bolts is 2.67 m / s to 4.69 m / s.

[0077] 2) The calculated distance between the butt bolt and the top of the catcher housing is in the range of 1.01mm to 2.92mm.

[0078] 3) By using a safety factor of 1.5, the speed range of 2.67m / s to 4.69m / s is expanded. After rounding, the resulting speed range is 1m / s to 7m / s. A light bubble is used to simulate the capture process within this speed range, the capture probability is statistically analyzed, and the position of the connecting bolts after capture is measured.

[0079] 4) Using a speed increment of 1 m / s, two rounds of capture tests were conducted on the three samples, one from small to large and the other from large to small. Throughout all six rounds of tests, successful capture was achieved within a speed range of 2.67 m / s to 4.69 m / s, with a distance from the top ranging from 0.98 mm to 2.40 mm. The results indicate that the maximum distance from the top of 2.40 mm did not exceed the upper limit of 2.92 mm, proving the reliability of the product's capture function.

[0080] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention based on the above-disclosed technical content without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for determining the reliability of bolt capture in a nut-separating device, characterized in that, include: Establish the relationship between the axial travel of the connecting bolt as it is pressed into the tapered hole of the catcher housing and the speed of the connecting bolt; Ground tests were conducted on the separating nut device to obtain the speed range of the connecting bolt after ignition; based on the established relationship between the axial travel of the connecting bolt extruding into the cone hole of the catcher housing and the speed of the connecting bolt, the range of axial travel of the connecting bolt extruding into the catcher housing at different speeds was obtained. The measured values ​​of the axial travel of the connecting bolts at different speeds were tested by pneumatic testing, and compared with the axial travel range of the connecting bolts being squeezed into the capture housing at different speeds to determine the reliability of the product. The relationship between the axial travel of the connecting bolt as it is pressed into the tapered hole of the catcher housing and the speed of the connecting bolt is as follows: in, d To allow the mating bolts to compress the axial travel of the housing, m For the quality of the connecting bolts, D The outer diameter of the bolt head. θ The cone angle of the shell, E Let be the elastic modulus of the shell. h The thickness of the shell wall. l The length of the compression ring that contacts the housing and the bolt head. u The coefficient of friction, v For the speed of the connecting bolts; The measured values ​​of the axial travel of the connecting bolts at different speeds are tested using pneumatic testing, and compared with the axial travel range of the connecting bolts being squeezed into the capture device housing at different speeds to determine product reliability, including: 31) Select N subsamples of the same specification of formal products; 32) Simulate different ejection speeds of the docking bolts, and record the entire process from ejection to capture using sensors or high-speed photography; statistically analyze the capture success rate of the docking bolts, and measure the height of the docking bolts from the top of the capture device to calculate the measured axial travel value of the docking bolts being squeezed into the capture device housing. 33) Compare the measured values ​​with the calculated axial travel range of the bolts being squeezed into the capture housing at different speeds. If the values ​​are within the range, and all samples can be captured and the corresponding measured axial travel values ​​are not less than the minimum axial travel range of the bolts being squeezed into the capture housing at different speeds, then the capture is considered reliable. 34) If there is an uncaptured sample or the measured value of axial travel is less than the minimum value of the axial travel range of the butt bolt pressing into the capture housing at different speeds, then add an extra sample and make the axial travel range of the butt bolt pressing into the capture housing at different speeds M times the original value, and repeat step 33). If all samples can be captured and the corresponding measured value of axial travel is not less than the minimum value of the axial travel range of the butt bolt pressing into the capture housing at different speeds after M times, then the capture is considered reliable; otherwise, the capture is considered unreliable.

2. The method for determining the reliability of bolt capture in a separating nut device according to claim 1, characterized in that, The separating nut device uses two redundant igniters with internal explosive charges as input energy. Through ground tests with different charge amounts, the performance data of the separating nut device within the envelope of the maximum and minimum charge amounts are obtained, corresponding to the speed range of the connecting bolt after ignition. Using the recorded speed range, the axial travel range of the connecting bolt pressing into the cone hole of the trap housing at different speeds is calculated based on the relationship between the axial travel of the connecting bolt pressing into the trap housing and the speed of the connecting bolt.

3. The method for determining the reliability of bolt capture in a separating nut device according to claim 1, characterized in that, The number of samples N is not less than 3.

4. The method for determining the reliability of bolt capture in a separating nut device according to claim 1, characterized in that, The value of M is 1.

5.

5. The method for determining the reliability of bolt capture in a separating nut device according to claim 1, characterized in that, Light bubbles were used to simulate the different ejection speeds of the bolts.

6. The method for determining the reliability of bolt capture in a separating nut device according to claim 1, characterized in that, Each sub-sample includes a mating bolt, a catcher base, and a catcher housing, ensuring that the product installation meets design requirements.

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