A method for rapidly detecting the sealing performance of a stepped seal structure

Abstract

This invention relates to a rapid method for testing the sealing performance of a stepped sealing structure, comprising: assembling the stepped sealing structures together to establish a dimensional chain; converting the gasket dimension A3, which characterizes the sealing reliability of the connection parts of the stepped sealing structure, into a tightness measurement value A0 using the dimensional chain; calculating the theoretical range of the tightness measurement value A0 and determining its upper and lower limit dimensions; designing a gap rod, which includes a through end and a stop end; and measuring the tightness measurement value A0 using the gap rod. If the through end passes the measurement, it indicates that the gasket is not over-compressed; if the stop end does not pass the measurement, it indicates that the seal is properly compressed. This method can efficiently and reliably test the sealing reliability of a stepped sealing structure in a liquid rocket engine after tightening.

Description

Technical Field

[0001] This invention relates to a rapid testing method for the sealing performance of stepped sealing structures, applicable to the testing of stepped sealing structures in liquid rocket engines. Background Technology

[0002] With engine deliveries increasing exponentially, frequent leaks have occurred at the tightening points of threaded pipe fittings in engine assembly, with the faults identified as leaks at the stepped connection points. Methods for controlling the tightening torque at these connections are affected by various factors (including the dimensions of the connection structure and the influence of anti-loosening adhesive), and in some cases, the effectiveness of tightening cannot be guaranteed. Therefore, a direct, accurate, and rapid inspection method is urgently needed for stepped sealing structures. Summary of the Invention

[0003] The technical problem solved by the present invention is to overcome the shortcomings of the prior art and provide a rapid testing device and method for the sealing performance of a stepped sealing structure, which can efficiently and reliably test whether the sealing of the stepped sealing structure of a liquid rocket engine is reliable after tightening.

[0004] The technical solution of this invention is:

[0005] A rapid testing method for the sealing performance of a stepped sealing structure includes the following steps:

[0006] (1) Assemble the stepped sealing structures together to establish a dimensional chain;

[0007] (2) The sealing gasket dimension A3, which characterizes the sealing reliability of the connection part of the stepped sealing structure, is converted into the tightness measurement value A0 through the dimension chain.

[0008] (3) Calculate the theoretical range of the tightness measurement value A0, and clarify the upper and lower limit dimensions of the tightness measurement value A0;

[0009] (4) Design a clearance bar, which includes a through end and a stop end;

[0010] (5) Use a gap bar to measure the tightness measurement value A0. If the through end passes, it indicates that the gasket is not over-compressed. If the stop end does not pass, it indicates that the seal is compressed to the required position.

[0011] In this invention, the stepped sealing structure includes: a concave stepped joint, a convex stepped joint, a sealing gasket, and an outer nut;

[0012] The steps on the concave step joint and the steps on the convex step joint mate to form a sealing surface. The sealing gasket is placed between the steps on the concave step joint and the steps on the convex step joint. The outer surface of the concave step joint is threaded. The outer nut is inserted from the direction of the convex step joint and screwed into the threads on the outer surface of the concave step joint to apply the clamping force to the sealing gasket.

[0013] The threads on the concave stepped joint interact with the threads on the outer nut, transmitting the force to the sealing gasket. The sealing gasket is compressed, connecting the inner cavities of the concave stepped joint and the convex stepped joint into one, ensuring that gas or liquid flows through without leakage.

[0014] Furthermore, the dimensional chain of the stepped sealing structure satisfies:

[0015] A0 + A5 - A4 = A1 - A2 + A3

[0016] Wherein, A5 is the machined dimension of the outer nut, A4 is the machined dimension of the raised step joint, A1 is the machined dimension of the concave step joint, A2 is the distance between the step plane and the end plane of the raised step joint, A3 is the sealing gasket dimension, and A0 is the tightness measurement value, i.e., the gap value between the concave step joint and the outer nut. The reliability of the sealing performance of the stepped sealing structure connection is directly characterized by the A3 value after connection, and then converted to the A0 value through the dimensional chain.

[0017] Furthermore, the theoretical range of the calculated tightness measurement value A0 is defined, and the upper and lower limit dimensions of the tightness measurement value A0 are clarified. Specifically, A1, A2, A4, and A5 are constant values, and A3 has an undeformed dimension value and a limit deformed dimension value according to the performance parameters of the sealing gasket.

[0018] Furthermore, the gap rod is a long rod-shaped structure with cylinders of different diameters at both ends. The end with the smaller diameter is the through end, and the end with the larger diameter is the stop end.

[0019] Furthermore, the tightness measurement value A0 is measured using a gap bar. That is, the gap bar is inserted into the gap between the concave step joint and the outer nut. If the through end can be inserted, it indicates that the gasket is not over-compressed. If the through end cannot be inserted, it indicates that the gasket is over-compressed. If the stop end cannot be inserted, it indicates that the seal is fully compressed. If the stop end can be inserted, it indicates that the seal is not fully compressed.

[0020] The advantages of this invention compared to the prior art are:

[0021] (1) The present invention provides a rapid testing device and method for determining the reliability of a stepped sealing structure in a liquid rocket engine after tightening. It is efficient and reliable, and can be extended to other stepped sealing structures.

[0022] (2) The method of the present invention realizes effective and quick inspection of the sealing performance after the step-type sealing structure is connected. At the same time, it changes the inspection mode from full production tracking to centralized inspection, eliminates the process confirmation link of inspectors, and promotes the optimization and upgrading of the inspection mode. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a stepped sealing structure;

[0024] Figure 2 This is a dimensional cross-sectional view of the stepped sealing structure. Detailed Implementation

[0025] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the stepped sealing structure includes: a concave stepped joint 1, a convex stepped joint 2, a sealing gasket 3, and an outer nut 4;

[0027] The steps on the concave step joint 1 and the steps on the convex step joint 2 cooperate to form a sealing surface. The sealing gasket 3 is placed between the steps on the concave step joint 1 and the steps on the convex step joint 2. The outer surface of the concave step joint 1 is provided with threads. The outer nut 4 is inserted from the direction of the convex step joint 2 and screwed into the threads on the outer surface of the concave step joint 1 to apply the clamping force to the sealing gasket.

[0028] The threads on the concave stepped joint interact with the threads on the outer nut, transmitting the force to the sealing gasket. The sealing gasket is compressed, connecting the inner cavities of the concave stepped joint and the convex stepped joint into one, ensuring that gas or liquid flows through without leakage.

[0029] like Figure 2 As shown, the dimensions of each part of the stepped sealing structure are as follows: A5 is the machined dimension of the outer nut, A4 is the machined dimension of the convex stepped joint, A1 is the machined dimension of the concave stepped joint, A2 is the distance between the step plane of the convex stepped joint and the end plane, A3 is the dimension of the sealing gasket, and A0 is the tightness measurement value, that is, the gap value between the concave stepped joint and the outer nut.

[0030] The dimensional chain of the stepped sealing structure satisfies:

[0031] A0 + A5 - A4 = A1 - A2 + A3

[0032] The reliability of the sealing performance of the stepped sealing structure connection is directly characterized by the A3 value after connection, which is then converted to the A0 value through a dimensional chain. A1, A2, A4, and A5 are constant values, while A3, based on the performance parameters of the gasket, has both undeformed and limit deformed dimensional values.

[0033] Through dimensional chain conversion, the A0 value, which characterizes the sealing reliability of the stepped sealing structure connection, has upper and lower deviations. That is, the manufactured gap bar includes a through end and a stop end. The through end indicates that the sealing gasket is not over-compressed, while the stop end indicates that the sealing element is compressed to the correct position.

[0034] The gap bar is a long rod-shaped structure with cylinders of different diameters at both ends. The end with the smaller diameter is the through end, and the end with the larger diameter is the stop end.

[0035] The tightness measurement value A0 is measured using a gap bar. This involves inserting the gap bar into the gap between the concave stepped joint and the outer nut. If the through end can be inserted, it indicates that the gasket is not over-compressed. If the through end cannot be inserted, it indicates that the gasket is over-compressed. If the stop end cannot be inserted, it indicates that the seal is fully compressed. If the stop end can be inserted, it indicates that the seal is not fully compressed.

[0036] Based on the above analysis, this invention proposes a rapid testing method for the sealing performance of a stepped sealing structure, comprising the following steps:

[0037] (1) Assemble the stepped sealing structures together to establish a dimensional chain;

[0038] (2) The sealing gasket dimension A3, which characterizes the sealing reliability of the connection part of the stepped sealing structure, is converted into the tightness measurement value A0 through the dimension chain.

[0039] (3) Calculate the theoretical range of the tightness measurement value A0, and clarify the upper and lower limit dimensions of the tightness measurement value A0;

[0040] (4) Design a clearance bar, which includes a through end and a stop end;

[0041] (5) Use a gap bar to measure the tightness measurement value A0 (the gap value between the concave step joint and the outer nut). If the through end passes, it indicates that the gasket is not over-compressed. If the stop end does not pass, it indicates that the seal is compressed to the correct position.

[0042] Example:

[0043] By studying the entire tightening process of the stepped sealing structure, it was found that the compression of the sealing gasket after tightening is a direct indicator of the sealing effectiveness. The compression of the sealing gasket can be verified by measuring the gap A0 between the concave stepped joint and the nut, making it a key indicator for verifying whether the seal is in place.

[0044] The theoretical range of clearance dimensions was calculated using a theoretical dimensional chain, and the measured clearance dimensions met the theoretical range requirements. Based on the statistically determined clearance dimension envelope, upper and lower limit dimensions of the clearance dimension were established, and a dedicated go / no-go end inspection fixture (clearance bar) was fabricated. After tightening the connection, the inspection personnel independently confirmed whether the clearance value met the requirements, checked the tightening torque record, and performed a rapid inspection of the tightening effectiveness of the threaded pipe joint.

[0045] After implementation, this method has been successfully verified through 30 engine process acceptance tests, proving its reliability and stability! The application of the rapid inspection method for the tightening effectiveness of threaded pipe fittings has changed the inspection mode from 4 days of continuous production monitoring to a mode of checking torque records and confirming clearance values, requiring only 2.5 hours. Under the production monitoring mode, inspection and confirmation are sequential with the main assembly process, occupying the assembly cycle; the rapid inspection method runs in parallel with the main assembly process, shortening the assembly cycle from 4 days / unit to 3 days / unit, increasing assembly efficiency by 25%, and reducing the number of people responsible for threaded pipe fitting assembly inspection from 3 to 2. The testing method has been optimized from process confirmation to a combination of process confirmation and result confirmation, achieving a 100% pass rate for threaded pipe fitting tightening.

[0046] This method enables effective and rapid inspection of the sealing performance of stepped sealing structures after connection. It also transforms the inspection process from continuous production monitoring to centralized testing, eliminating the need for inspector verification and thus promoting an optimized and upgraded inspection model. It will be subsequently applied to different models.

[0047] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A rapid testing method for the sealing performance of a stepped sealing structure, characterized in that, include: By assembling the stepped sealing structures together, a dimensional chain is established; The sealing gasket dimension A3, which characterizes the sealing reliability of the connection part of the stepped sealing structure, is converted into a tightness measurement value A0 through the dimensional chain. Calculate the theoretical range of the tightness measurement value A0, and determine the upper and lower limit dimensions of the tightness measurement value A0; Design a clearance bar, which includes a go end and a stop end; The tightness measurement value A0 is measured using a gap bar. If the through end passes through, it indicates that the gasket is not over-compressed, and if the stop end does not pass through, it indicates that the seal is fully compressed.

2. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 1, characterized in that: The stepped sealing structure includes: a concave stepped joint (1), a convex stepped joint (2), a sealing gasket (3), and an outer nut (4); The steps on the concave step joint (1) and the steps on the convex step joint (2) are matched to form a sealing surface. The sealing gasket (3) is placed between the steps on the concave step joint (1) and the steps on the convex step joint (2). The outer surface of the concave step joint (1) is provided with threads. The outer nut (4) is inserted from the direction of the convex step joint (2) and screwed into the threads on the outer surface of the concave step joint (1) to apply the clamping force to the sealing gasket.

3. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 2, characterized in that: The threads on the concave stepped joint interact with the threads on the outer nut, transmitting the force to the sealing gasket. The sealing gasket is compressed, connecting the inner cavities of the concave stepped joint and the convex stepped joint into one, ensuring that gas or liquid flows through without leakage.

4. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 2, characterized in that: The dimensional chain of the stepped sealing structure satisfies: A0 + A5 - A4 = A1 - A2 + A3 Among them, A5 is the machining dimension of the outer nut, A4 is the machining dimension of the convex step joint, A1 is the machining dimension of the concave step joint, A2 is the distance between the step plane of the convex step joint and the end plane, A3 is the sealing gasket dimension, and A0 is the tightness measurement value, that is, the gap value between the concave step joint and the outer nut.

5. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 4, characterized in that: The reliability of the sealing performance of the stepped sealing structure connection is directly characterized by the A3 value after connection, and then converted to the A0 value through the dimensional chain.

6. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 4, characterized in that: The theoretical range of the calculated tightness measurement value A0 is defined, and the upper and lower limit dimensions of the tightness measurement value A0 are specified as follows: A1, A2, A4, and A5 are constant values, and A3 has an undeformed dimension value and a limit deformed dimension value according to the performance parameters of the sealing gasket.

7. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 1, characterized in that: The gap bar is a long rod-shaped structure with cylinders of different diameters at both ends. The end with the smaller diameter is the through end, and the end with the larger diameter is the stop end.

8. The rapid testing method for the sealing performance of a stepped sealing structure according to claim 7, characterized in that: The tightness measurement value A0 is measured by inserting a gap bar into the gap between the concave stepped joint and the outer nut. If the through end can be inserted, it indicates that the gasket is not over-compressed; if the through end cannot be inserted, it indicates that the gasket is over-compressed. If the stop end cannot be inserted, it indicates that the seal is fully compressed; if the stop end can be inserted, it indicates that the seal is not fully compressed.

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