Design method of aero-engine pipeline joint with coaxiality maintaining function

Abstract

The invention relates to the technical field of aero-engine pipeline joints, in particular to a design method of an aero-engine pipeline joint with a coaxiality maintaining function. The pipeline joint structure comprises a conical surface pipe, a ball head pipe joint and an outer sleeve nut, and the length of a thread pair matching end of the outer sleeve nut is increased so as to improve the coaxiality with the conical surface pipe; an annular boss is arranged on the inner side of the outer sleeve nut, an annular groove is formed in the pressing face of the ball head pipe joint, and the annular boss and the annular groove are meshed to improve the coaxiality with the ball head pipe joint. Manufacturing the structural parts; the annular boss and the annular groove are meshed and coated with lubricating grease; and after the conical surface pipe is centered and positioned, the jacket nut is screwed to preset torque. By means of the double design of the lengthened threads and the boss-groove meshing, the axial consistency of the conical surface pipe, the ball head pipe joint and the outer sleeve nut is forcibly guaranteed, the contact stress of the conical surface and the ball head pipe joint is evenly distributed, the problem of oil leakage caused by coaxiality deviation is thoroughly solved, the sealing reliability is improved, and the maintenance cost of an engine is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engine pipe joints, and in particular to a design method of an aero-engine pipe joint with a coaxiality maintaining function. Background Art

[0002] Aircraft engine pipes and their joints are common external accessory components. Currently, the most common pipe joint assembly is a cone-ball fit structure, which consists of a tapered pipe, a ball joint, and a jacket nut. The tapered pipe and the ball joint adopt a cone-ball line contact fit, and the thread torque of the jacket nut compresses the two to form a pipeline sealing effect. The traditional structural form is shown in the figure. Figure 1 As shown. Although the traditional structure adopts the tapered ball line contact fit to increase contact stress and improve the sealing of the pipeline, it is difficult to always maintain the axial coaxiality of the tapered tube, ball head pipe joint, and outer nut during the actual assembly process. As a result, there is a slight axial deviation between the three components in the assembled state, making oil leakage in the pipeline joint a common problem. When there is a deviation in the coaxiality of the three components, the uniformity of the contact stress distribution along the circumference is destroyed, as shown in the figure. Figure 2 As shown in the figure, areas with less contact stress are prone to oil leakage, which increases the maintenance cost of the engine. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides a method for designing an aero-engine pipe joint with a coaxiality maintaining function; the specific technical solution is as follows:

[0004] A design method for an aero-engine pipe joint with a coaxiality maintaining function, wherein the pipe joint structure includes a tapered pipe, a ball head pipe joint and a jacket nut;

[0005] The length of the thread pair mating end of the outer sleeve nut is greater than that of the traditional outer sleeve nut, so as to improve the coaxiality with the tapered tube;

[0006] The inner pressing surface of the outer sleeve nut is provided with an annular boss;

[0007] The pressing surface of the ball head pipe joint is provided with an annular groove;

[0008] The outer sleeve nut is connected to the tapered tube through a threaded pair, and the outer sleeve nut is engaged with the ball head pipe joint through an annular boss and an annular groove, which is used to improve the coaxiality of the outer sleeve nut and the ball head pipe joint.

[0009] A design method for an aero-engine pipe joint with a coaxiality maintaining function, wherein a preferred solution is that the cross-sectional shapes of the annular boss and the annular groove match each other to achieve close engagement between the two.

[0010] A method for designing an aero-engine pipe joint with a coaxiality maintaining function, wherein the pipe joint manufacturing comprises the following steps:

[0011] Step 1: Complete the manufacturing and processing of the outer nut and the ball joint according to the dimensions and process requirements of the parts drawing. The tapered tube remains unchanged using the original drawing and process requirements.

[0012] Step 2: During assembly, first install the outer sleeve nut and the ball joint, engage the outer sleeve nut with the ball joint through the annular boss and the annular groove, and apply grease to the mating surfaces to ensure flexibility of circumferential rotation;

[0013] Step 3: When assembling with the tapered tube, align the tapered tube and the ball head pipe joint, gradually screw the outer sleeve nut into the axial direction through the threaded pair mating end on the outer side of the tapered tube, and tighten it according to the tightening torque requirements. The thread tightening torque is converted into axial force to tighten the pipe joint structure to achieve the pipeline sealing effect.

[0014] The preferred solution of the method for designing an aero-engine pipe joint with a coaxiality maintaining function is to ensure that the axes of the tapered tube, the ball head pipe joint and the outer sleeve nut coincide with each other through the centering positioning in step three.

[0015] Beneficial effects

[0016] Compared to currently common structures, the technical solution of this invention effectively addresses the oil leakage problem caused by poor axial alignment between mating parts in pipelines. This design approach avoids the premature repair and repeated test runs of aircraft engines caused by such issues, effectively improving operational reliability and stability and reducing engine maintenance and repair costs. This invention is widely applicable to the design, manufacture, and use of aircraft engine pipelines and can also be extended to similar pipe joint connection structures in other machinery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of a pipe joint assembly with a traditional cone-ball fitting structure;

[0018] Figure 2 A schematic diagram of the cross-sectional three-dimensional structure of a pipe joint assembly with a traditional cone-ball matching structure;

[0019] Figure 3 This is a schematic diagram of the structure of an aircraft engine pipe joint with a coaxiality maintenance function;

[0020] Figure 4 Schematic diagram of the cross section and the finite element calculation results of the contact stress when there is a small axial deviation angle;

[0021] Figure 5Schematic diagram of the improved outer nut structure cross section;

[0022] Figure 6 Schematic diagram of the cross-section of the improved ball head pipe joint structure.

[0023] In the figure: 1-conical tube, 2-ball head pipe joint, 3-jacket nut, 4-thread pair matching end, 5-annular boss, 6-annular groove. DETAILED DESCRIPTION

[0024] The following is combined with Figure 1-6 The present invention is described in detail, but the protection scope of the present invention is not limited by the accompanying drawings.

[0025] A method for designing an aero-engine pipe joint with a coaxiality maintaining function, wherein the pipe joint comprises a tapered pipe 1, a ball pipe joint 2, and a jacket nut 3;

[0026] The length of the thread pair matching end 4 of the outer sleeve nut 3 is greater than that of the thread pair matching end of the traditional outer sleeve nut, and is used to improve the coaxiality with the tapered tube 1;

[0027] The inner pressing surface of the outer sleeve nut 3 is provided with an annular boss 5;

[0028] The pressing surface of the ball pipe joint 2 is provided with an annular groove 6;

[0029] The outer sleeve nut 3 is connected to the tapered tube 1 through a threaded pair, and the outer sleeve nut 3 is engaged with the ball head pipe joint 2 through an annular boss 5 and an annular groove 6, which is used to improve the coaxiality of the outer sleeve nut 3 and the ball head pipe joint 2.

[0030] The cross-sectional shapes of the annular boss 5 and the annular groove 6 match each other to achieve close engagement between the two.

[0031] A method for designing an aero-engine pipe joint with a coaxiality maintaining function, wherein the pipe joint manufacturing process includes the following steps:

[0032] Step 1: Complete the manufacturing and processing of the outer nut 3 and the ball joint 2 according to the dimensions and process requirements of the parts drawing. The tapered tube 1 remains unchanged using the original drawing and process requirements.

[0033] Step 2: During assembly, first install the outer sleeve nut 3 and the ball joint 2, engage the outer sleeve nut 3 with the ball joint 2 through the annular boss 5 and the annular groove 6, and apply grease to the mating surfaces to ensure flexibility in circumferential rotation;

[0034] Step 3: When assembling with the tapered tube 1, align the tapered tube 1 and the ball head pipe joint 2, gradually screw the outer sleeve nut 3 into the threaded pair matching end 4 on the outside of the tapered tube 1 in the axial direction, and tighten it according to the tightening torque requirements. The thread tightening torque is converted into axial force to tighten the pipe joint structure to achieve the pipeline sealing effect.

[0035] The alignment in step three ensures that the axes of the tapered tube 1, the ball head tube joint 2 and the outer sleeve nut 3 coincide with each other.

Claims

1. A design method for an aero-engine pipe joint with a coaxiality maintaining function, characterized by: The pipe joint structure comprises a conical pipe (1), a ball pipe joint (2) and a jacket nut (3); The length of the threaded pair mating end (4) of the outer sleeve nut (3) is greater than that of the threaded pair mating end of a conventional outer sleeve nut, and is used to improve the coaxiality with the conical tube (1); The inner pressing surface of the outer sleeve nut (3) is provided with an annular boss (5); The pressing surface of the ball-end pipe joint (2) is provided with an annular groove (6); The outer sleeve nut (3) is connected to the conical tube (1) via a threaded pair, and the outer sleeve nut (3) is meshedly connected to the ball-end tube joint (2) via an annular boss (5) and an annular groove (6), so as to improve the coaxiality of the outer sleeve nut (3) and the ball-end tube joint (2).

2. The method for designing an aero-engine pipe joint with a coaxiality maintaining function according to claim 1, characterized in that: The cross-sectional shapes of the annular boss (5) and the annular groove (6) match each other to achieve close engagement between the two.

3. The method for designing an aero-engine pipe joint with a coaxiality maintaining function according to claim 1, characterized in that: The pipe joint manufacturing process includes the following steps: Step 1: Complete the manufacturing and processing of the outer sleeve nut (3) and the ball head pipe joint (2) according to the dimensions of the parts drawing and the process requirements, and the tapered tube (1) remains unchanged using the original drawing and process requirements; Step 2: During assembly, first install the outer sleeve nut (3) and the ball joint (2), engage the outer sleeve nut (3) with the ball joint (2) through the annular boss (5) and the annular groove (6), and apply grease to the mating surface to ensure flexibility of circumferential rotation; Step 3: When assembling with the conical tube (1), align the conical tube (1) and the ball head tube joint (2), gradually screw the outer sleeve nut (3) and the threaded pair matching end (4) on the outer side of the conical tube (1) in along the axial direction, and tighten it according to the tightening torque requirement, and convert the thread tightening torque into axial force to press the pipeline joint structure to achieve the pipeline sealing effect.

4. The method for designing an aero-engine pipe joint with a coaxiality maintaining function according to claim 3, characterized in that: The alignment in step three ensures that the axes of the tapered tube (1), the ball tube joint (2) and the outer sleeve nut (3) coincide with each other.

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