Titanium alloy cold extrusion joint

Abstract

The titanium alloy cold extrusion joint is of a cylindrical structure made of titanium alloy and comprises a rigid connector section, an extrusion section and a flexible connector section, a boss is arranged on the inner side of the extrusion section and is in transition connection with the inner side wall along a certain slope angle, a first step-shaped convex ring is arranged on the outer side of the extrusion section, and the portion, close to the rigid connector section, of the step-shaped convex ring is a first large-diameter section; a second step-shaped protruding ring is arranged on the outer side of the rigid connector section and is a second large-diameter section away from the extrusion section, a protruding ring is arranged on the outer side of the flexible connector section, a groove is formed in the end face of the protruding ring in the radial direction, and the outer diameter of the first large-diameter section is larger than the outer diameter of the second large-diameter section and the outer diameter of the protruding ring. By providing high interference amount, the joint is tightly attached to the titanium alloy frame plate of the aircraft after generating plastic deformation, certain anti-push and anti-torsion performance is achieved while the sealing effect is achieved, beneficial hole circumferential pressure stress is provided for the titanium alloy frame plate under the cooperation of the high interference amount, the fatigue life of the titanium alloy frame plate of the aircraft is effectively prolonged, and the service life of the titanium alloy frame plate of the aircraft is prolonged. And connectors at two ends are connected with external conduits, so that long-life frame-penetrating connection is realized.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy aircraft fuel system pipeline joint devices, and specifically discloses a titanium alloy cold extrusion joint. Background Art

[0002] The duct components of the aircraft fuel system are generally connected through flanges and connectors. The aircraft fuel system has a relatively low pressure, and the connectors are generally required not to leak before a certain pressure is reached, and not to fall off before a certain push-out force and unscrewing torque are reached.

[0003] Aircraft work in harsh environments and complex working conditions. Making a large number of satellite holes in the aircraft structural frame plate to achieve bolt connection will seriously reduce the fatigue life of the aircraft fuselage structure. With the extensive application of titanium and titanium alloys in advanced aircraft, serious potential corrosion will occur with traditional aluminum alloy flange structures, reducing the service life and reliability of the aircraft. At the same time, aluminum alloy or copper alloy frame joints cannot provide sufficient fatigue gain for the aircraft and enhance fatigue life due to the large difference in material strength between them and titanium metal fuselage materials. In addition, they cannot guarantee the sealing quality, resulting in fuel system leakage and affecting flight safety. They are now banned from use on advanced aircraft.

[0004] Therefore, how to avoid potential corrosion and improve the fatigue life of the fuselage frame while ensuring the sealing requirements is a key issue in aircraft assembly. Summary of the invention

[0005] The purpose of the present invention is to provide a titanium alloy cold extruded joint that meets the requirements of long life, light weight and strong sealing of the titanium alloy aircraft frame penetration part, so as to overcome the problems of low fatigue life, heavy weight and severe potential corrosion of the titanium alloy aircraft frame penetration part, and ensure the reliability and safety of the aircraft operation.

[0006] The technical solution of the present invention is as follows: A titanium alloy cold extrusion joint, a cylindrical structure made of titanium alloy, including a rigid interface section, an extrusion section, and a flexible interface section. A boss is provided on the inner side of the extrusion section, and the boss is transitionally connected to the inner wall along a certain slope angle. A step-shaped convex ring 1 is provided on the outer side of the extrusion section. The step-shaped convex ring is close to the rigid interface section as the large diameter section 1, and a step-shaped convex ring 2 is provided on the outer side of the rigid interface section. The step-shaped convex ring 2 is away from the extrusion section as the large diameter section 2. A convex ring is provided on the outer side of the flexible interface section, and a groove is provided on the end face of the convex ring in the radial direction. The outer diameter of the large diameter section 1 is larger than the outer diameters of the large diameter section 2 and the convex ring.

[0007] Furthermore, the step-shaped convex ring has a thickness of 1 to 4 mm and is the main load-bearing structural part, bearing the axial force generated by material deformation during extrusion installation. Both ends of the joint part are external connector interfaces, and the thickness can be determined according to the actual needs of various types of external pipeline connectors.

[0008] Furthermore, the inner diameter of the boss is slightly smaller than the core rod for installation, but slightly larger than the inner diameter of the aircraft pipeline, so as to ensure interference installation while not affecting the internal flow resistance.

[0009] Furthermore, the groove diameter and the diameter of the second small diameter section of the stepped convex ring are both smaller than the diameter of the first small diameter section of the stepped convex ring, and larger than the inner diameter of the boss, thereby ensuring that the titanium alloy cold extruded joint 1 can be freely installed in both directions while having sufficient structural strength.

[0010] Furthermore, the boss and its chamfered position are coated with a solid dry film lubricant, the friction coefficient of the solid dry film lubricant is ≤0.05, and the temperature resistance can reach 300°C, thereby achieving the effect of reducing the tension during the joint extrusion installation process.

[0011] Furthermore, when not installed, the extrusion section is clearance-matched with the titanium alloy aircraft frame plate.

[0012] Beneficial effects of the present invention:

[0013] (1) The fatigue strengthening effect is outstanding. Through high interference fit, the titanium alloy cold extrusion joint and the frame plate part produce grain dislocation, which introduces residual compressive stress on a macro scale, eliminates the harmful tensile stress around the frame plate hole, and effectively improves the fatigue life around the hole.

[0014] (2) Significantly improve installation efficiency. Titanium alloy cold extruded joints are easy and quick to install, do not require a large number of bolt connections, have low labor costs, high reliability, and good process control effects.

[0015] (3) The weight is greatly reduced. The titanium alloy cold extruded joint consists of only one part and does not require a large number of bolt connections. The overall weight is greatly reduced compared to the flange-threaded connection, and the weight reduction effect is outstanding.

[0016] (4) Good electrical conductivity. After the extrusion installation is completed, the cold extruded joint fits tightly with the aircraft frame plate, has a large contact area and is not affected by long-term use. It can be regarded as an integral part of the frame plate, has high electrical conductivity, and has good conductive effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings herein are incorporated into and constitute a part of the specification, showing embodiments consistent with the present invention, and together with the specification, are used to explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0018] Figure 1 A schematic diagram of the structure of a titanium alloy cold extrusion joint provided by the present invention;

[0019] Figure 2 A stereoscopic view of a titanium alloy cold extruded joint provided by the present invention;

[0020] Figure 3 A schematic diagram of the structure of the titanium alloy cold extrusion joint provided by the present invention being fixed on a titanium alloy frame plate of an aircraft;

[0021] Figure 4 Schematic diagram of different connector structures connected to the titanium alloy cold extruded joint provided by the present invention;

[0022] In the attached figure: 1-Titanium alloy cold extrusion joint

[0023] 11-rigid interface section, 111-convex ring 2, 1111-large diameter section 2

[0024] 12-extrusion section, 121-boss, 122-convex ring 1, 1221-large diameter section 1

[0025] 13-flexible interface section, 131-convex ring, 1311-groove

[0026] 2- core rod, 3- aircraft titanium alloy frame plate, 4- rigid connector, 5- flexible connector,

[0027] α-slope angle. DETAILED DESCRIPTION

[0028] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present invention will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0029] See also Figure 1-2, the figure shows a schematic diagram of the titanium alloy cold extrusion joint structure provided by the present invention, which is a cylindrical structure made of titanium alloy, including a rigid interface section 11, an extrusion section 12, and a flexible interface section 13. The inner side of the extrusion section 12 is provided with a boss 121, and the boss 121 is transitionally connected with the inner wall along a certain slope angle α. The outer side of the extrusion section 12 is provided with a step-shaped convex ring 122, and the step-shaped convex ring 122 is close to the rigid interface section 11 as a large diameter section 1221, and the outer side of the rigid interface section 11 is provided with a step-shaped convex ring 2 111, and the step-shaped convex ring 2 111 is far away from the extrusion section 12 as a large diameter section 2 1111, and the outer side of the flexible interface section 13 is provided with a convex ring 131, and the end face of the convex ring 131 is provided with a groove 1311 in the radial direction, and the outer diameter of the large diameter section 1221 is larger than the outer diameters of the large diameter section 2 1111 and the convex ring 131. The thickness of the stepped convex ring 122 is 1 to 4 mm. It is the main load-bearing structural part and bears the axial force generated by the deformation of the material during extrusion installation. The two ends of the titanium alloy cold extrusion joint 1 are external connector interfaces, which can be determined according to the actual needs of various types of external pipeline connectors. The inner diameter of the boss 121 is slightly smaller than the installation core rod 2, but slightly larger than the inner diameter of the aircraft pipeline, so that while ensuring interference installation, it does not affect the internal flow resistance. When not installed, the extrusion section 12 and the aircraft titanium alloy frame plate 3 are clearance-matched, and the matching accuracy is high above H7, ensuring that the stress during extrusion installation is effectively transmitted to the frame plate. The boss 121 and its slope angle α are coated with a solid dry film lubricant to reduce the tension required during the joint extrusion installation process. The friction coefficient of the solid dry film lubricant is ≤0.05, and the temperature resistance can reach 300°C, thereby achieving the effect of reducing the tension during the joint extrusion installation process. The diameter of the groove 1311 and the diameter of the small diameter section of the stepped convex ring 111 are both smaller than the diameter of the small diameter section of the stepped convex ring 122, and larger than the inner diameter of the boss 121, thereby ensuring that the titanium alloy cold extruded joint 1 can be freely installed in both directions while having sufficient structural strength. Special coatings or special treatments can be added to the outside of the titanium alloy cold extruded joint 1 to give the joint some special properties, such as: adding adhesives to improve its sealing effect, adding surface treatments to improve corrosion resistance, etc.

[0030] Figure 3Schematic diagram of the structure of titanium alloy cold extrusion joint fixed on titanium alloy frame plate of aircraft, the titanium alloy cold extrusion joint 1 is placed in the titanium alloy frame plate 3 of aircraft, and the interference size between the boss 121 and the core rod 2 provides a high interference amount, and the installation tool is used to pull the tapered core rod 2 to make the protective bushing expand radially, and the inner wall of the titanium alloy cold extrusion joint 1 is extruded through the inner wall extrusion part of the titanium alloy cold extrusion joint 1 to produce elastic-plastic deformation, and the outer wall of the extrusion part of the titanium alloy cold extrusion joint 1 and the hole of the aircraft titanium alloy frame plate 3 are elastically deformed to form deformation stress, and the titanium alloy cold extrusion joint 1 is fixed on the titanium alloy frame plate 3 of aircraft, so that the joint fits tightly with the frame plate after plastic deformation, and the sealing is completed. At the same time, under the cooperation of high interference amount, the frame plate will be provided with beneficial hole circumferential compressive stress, which effectively improves the fatigue life of the frame plate.

[0031] Figure 4 Schematic diagram of titanium alloy cold extruded joint connected with different connector structures. The titanium alloy cold extruded joint 1 is fixed on the aircraft titanium alloy frame plate 3, with one end connected to the flexible connector 5 and the other end connected to the rigid connector 4. Different connectors can be connected according to different working conditions.

[0032] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Any modification or equivalent substitution made to the technical solution of the present invention by ordinary technicians in this field shall be included in the scope of the claims of the present invention as long as it does not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A titanium alloy cold extrusion joint, characterized in that: A cylindrical structure made of titanium alloy comprises a rigid interface section (11), an extrusion section (12), and a flexible interface section (13); a boss (121) is provided on the inner side of the extrusion section (12); the boss (121) is transitionally connected to the inner wall along a certain slope angle (α); a step-shaped convex ring (122) is provided on the outer side of the extrusion section (12); the step-shaped convex ring (122) is close to the rigid interface section (11) and is a large diameter section (1221); a step-shaped convex ring (111) is provided on the outer side of the rigid interface section (11); the step-shaped convex ring (111) is far away from the extrusion section (12) and is a large diameter section (1111); a convex ring (131) is provided on the outer side of the flexible interface section (13); a groove (1311) is provided on the end face of the convex ring (131) in a radial direction; the outer diameter of the large diameter section (1221) is greater than the outer diameters of the large diameter section (1111) and the convex ring (131).

2. The titanium alloy cold extrusion joint according to claim 1, characterized in that: The thickness of the stepped protruding ring 1 (122) is 1 to 4 mm.

3. The titanium alloy cold extrusion joint according to claim 1, characterized in that: The inner diameter of the boss (121) is slightly smaller than the installation core rod (2), but slightly larger than the inner diameter of the aircraft pipeline.

4. The titanium alloy cold extrusion joint according to claim 1, characterized in that: The diameter of the groove (1311) and the diameter of the small diameter section of the stepped convex ring (111) are both smaller than the diameter of the small diameter section of the stepped convex ring (122), and larger than the inner diameter of the boss (121).

5. The titanium alloy cold extrusion joint according to claim 1, characterized in that: When not installed, the extrusion section (12) and the titanium alloy aircraft frame plate (3) are clearance-matched.

6. The titanium alloy cold extrusion joint according to claim 1, characterized in that: The boss (121) and its slope angle are coated with a solid dry film lubricant.

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