Lightweight high corrosion resistant threaded puller for aviation and its manufacturing method

Abstract

The application discloses a light and high-corrosion-resistant threaded puller for aviation and a manufacturing method thereof. The threaded puller comprises a core rod, a ring, a puller sleeve, a puller body and a driving nut which are sequentially sleeved on the core rod from bottom to top and are threadedly connected, the ring is arranged in a stepped hole of the puller sleeve and is in contact with a guide cone portion at the bottom of the puller body, the core rod and the puller body are made of titanium alloy material, the puller sleeve is made of pure titanium or titanium alloy material, and the ring is made of polyformal material. The application realizes the overall lightweight design of the threaded puller, the weight of the threaded puller is reduced by more than 10% compared with traditional steel materials, the fuel efficiency and the effective load of the aircraft are improved, meanwhile, the titanium alloy material has excellent corrosion resistance and can adapt to the strong corrosion environment such as marine atmosphere, and the service life of the threaded puller is significantly prolonged.

Description

Technical Field

[0001] This invention relates to the field of fastener technology, specifically to a lightweight, highly corrosion-resistant threaded rivet for aerospace applications and its manufacturing method. Background Technology

[0002] In aircraft and aerospace vehicles, composite materials are extensively used as airframe materials to strictly control weight. However, during assembly, situations often arise where installation space is limited, preventing workers from operating from both sides. For these single-sided installation scenarios, blind rivets (threaded rivets) are typically used to securely connect composite materials and aluminum alloy structures.

[0003] Existing threaded tapers have the following technical problems in practical applications:

[0004] 1) It is difficult to achieve both lightweight and high corrosion resistance in materials. Currently, the core material for pull studs is mostly made of high-temperature alloys or stainless steel. However, with the increasing demands for weight reduction and corrosion resistance in next-generation aircraft, traditional steel is no longer sufficient to meet the requirements for use in extreme environments such as the ocean. Specifically, steel has a high density, which is detrimental to aircraft weight reduction; at the same time, in highly corrosive environments such as the marine atmosphere, stainless steel and high-temperature alloys have limited corrosion resistance, posing a risk of corrosion.

[0005] 2) Poor surface flatness after installation After the existing pull studs are installed, the stud head itself has a wrench groove such as a cross groove or a flower groove. After riveting, these grooves will leave a concave gap, and the position of the core rod breakage is uncertain (large tolerance), resulting in an uneven installation surface, which is not conducive to the aerodynamics of the aircraft shape and affects the overall surface flatness of the fuselage.

[0006] Therefore, providing a lightweight, highly corrosion-resistant threaded pull pin for aviation and its manufacturing method is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a lightweight and highly corrosion-resistant threaded pull pin for aviation and a method for manufacturing the same. After the pull pin is installed, the material remaining on the aircraft surface is titanium alloy and polyoxymethylene, which meets the requirements of lightweight and high corrosion resistance in marine environments.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A lightweight, highly corrosion-resistant threaded pull pin for aviation applications includes a core rod, a ring, and a pin sleeve, a pin body, and a drive nut, which are sequentially sleeved on the core rod and threaded together from bottom to top. The ring is placed in a stepped hole in the pin sleeve and contacts a guide cone at the bottom of the pin body. The core rod and the pin body are both made of titanium alloy, the pin sleeve is made of pure titanium or titanium alloy, and the ring is made of polyoxymethylene.

[0009] By adopting the above technical solutions, the present invention has the following beneficial effects: The overall lightweight design of the threaded tappet is achieved, reducing weight by more than 10% compared to traditional steel, which helps improve the aircraft's fuel efficiency and payload. At the same time, the titanium alloy material has excellent corrosion resistance, enabling it to adapt to highly corrosive environments such as the marine atmosphere, significantly extending the service life of the tappet.

[0010] Furthermore, the nail body and the core rod, as well as the core rod and the drive nut, are both fitted with double-threaded connections.

[0011] The beneficial effects of adopting the above-mentioned further technical solutions are that by using double-threaded fit between the nail body and the core rod, and between the core rod and the drive nut, the lead of the double-threaded fit is twice that of the single-threaded fit under the same pitch conditions, thereby improving the thread processing efficiency (double the thread rolling / tapping efficiency) and installation efficiency (half the number of tightening turns), and effectively reducing manufacturing costs and assembly time.

[0012] Furthermore, the end face of the nail head that contacts the drive nut is a smooth plane.

[0013] The beneficial effects of adopting the above-mentioned further technical solutions are that by setting the end face of the nail head that contacts the drive nut to a smooth plane, the wringing groove type such as the cross groove or flower groove on the traditional pull nail head is eliminated, thereby eliminating the concave gap left on the surface of the nail head after riveting, ensuring that the surface is flat after installation, which is beneficial to the aerodynamics of the aircraft shape, and at the same time eliminating the stress concentration and corrosion risk caused by the concave area.

[0014] Furthermore, the titanium alloy material is any one of TB9, TC4, and TA1.

[0015] The beneficial effects of adopting the above-mentioned further technical solutions are that, by limiting the specific grades of titanium alloy materials, the range of achievable material selection is clarified. TB9 titanium alloy, after aging treatment, can achieve a tensile strength of over 1300 MPa, making it suitable for high-strength components such as core rods; TC4 titanium alloy has good comprehensive mechanical properties and processability, making it suitable for nail bodies; TA1 pure titanium has good plasticity and corrosion resistance, making it suitable for nail sleeves. Selecting appropriate titanium alloy materials according to the functional requirements of different components achieves an optimal match between performance and cost.

[0016] A method for manufacturing a lightweight, highly corrosion-resistant threaded pull pin for aviation as described above, comprising manufacturing the pin body, drive nut, core rod, and pin sleeve respectively.

[0017] By adopting the above technical solutions, the present invention has the following beneficial effects: By manufacturing the nail body, drive nut, core rod, and nail sleeve independently, each component can be processed using its own optimal processing technology and heat treatment parameters. This ensures the dimensional accuracy and mechanical properties of each component, providing a high-quality component foundation for subsequent assembly and improving the finished product qualification rate and product consistency.

[0018] The further steps in manufacturing the nail body are as follows: 1) Blank preparation: Select TC4 titanium alloy wire; 2) Upsetting: The TC4 titanium alloy wire is placed in a warm upsetting machine, and the nail head, shank, and transition arc at the connection between the nail head and shank are warm upset in one step using the corresponding mold to obtain a semi-finished nail body; 3) Cleaning: The forged blank is vibrated and polished to remove surface dirt and raw material coatings generated during upsetting; 4) Machining: Machining the nail head; Drilling a tapping hole in the nail body using a drilling machine; 5) Tapping: Use a double-starting thread tap with the same pitch to machine a double-starting thread on the inner wall of the ground nail body semi-finished product; 6) CNC centerless grinder: The heat-treated semi-finished product is placed on a centerless grinder to grind the outer diameter of the rod. 7) Heat treatment: For the first heat treatment, the cleaned nail semi-finished product is subjected to solution heat treatment, heated to 900-980℃, held for 30-60 minutes, and then water-cooled; for the second heat treatment, the air-cooled nail semi-finished product is placed in a vacuum aging furnace at 480℃-580℃ for 4-6 hours, and then cooled with the furnace. 8) Surface treatment: The nail body semi-finished product is passivated or coated with aluminum to obtain the finished product.

[0019] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the use of warm upsetting one-time forming process to form the nail head, shank and under-head transition arc of the nail body in one step reduces the processing steps, improves production efficiency, and at the same time ensures the geometric accuracy of the under-head R, which is conducive to eliminating stress concentration; the use of double-thread same pitch thread tap to process internal threads improves tapping efficiency; the use of solution + aging dual-stage heat treatment (900-980℃ solution water cooling + 480-580℃ aging furnace cooling) enables TC4 titanium alloy to obtain excellent comprehensive mechanical properties.

[0020] Furthermore, the manufacturing steps for the drive nut are as follows: 1) Preparation of drive nut blank: Select hexagonal alloy steel of predetermined specifications as the blank; 2) Machining: Drilling equipment is used to machine the pilot hole in the hexagonal alloy steel billet; 3) Heat treatment: Solution heat treatment: Place the semi-finished drive nut in a vacuum solution furnace at 850℃-900℃ and hold for 45min-60min, then oil cool; Tempering treatment: Place the semi-finished drive nut after solution heat treatment in a vacuum furnace at 350℃-400℃ and hold for 2h-3h, then air cool, so that its hardness reaches 45-55HRC. 4) Use a double-starting, same-pitch thread tap to machine a double-starting internal thread on the nut semi-finished product; 5) Surface treatment: The heat-treated drive nut semi-finished product is then subjected to nickel plating, zinc plating, or chromium plating to obtain the finished product.

[0021] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the heat treatment process of solution treatment (850-900℃, oil cooling) followed by tempering (350-400℃, air cooling) enables the drive nut to achieve a hardness of 45-55HRC, ensuring that the drive nut has sufficient strength and wear resistance; the use of double-threaded taps to process the internal threads improves processing efficiency; and surface nickel plating, zinc plating, or chromium plating improves the corrosion resistance and surface hardness of the drive nut, extending its service life.

[0022] Furthermore, the manufacturing steps for the core rod are as follows: 1) Raw material: TB9 titanium alloy wire is selected as the raw material. TB9 titanium alloy wire is in the solution heat-treated state, with a tensile strength ≥1000MPa and a lubricating coating on the surface. 2) Cold heading: Place the TB9 titanium alloy wire in a four-die cold heading machine, and use dies of the corresponding specifications to cold head the head, large rod, small rod and transition arc at the head rod connection in one step to obtain a semi-finished TB9 titanium alloy core rod with steps. 3) Coating removal: The semi-finished core rod is passed through a vibratory polishing machine and an acid pickling line in sequence to remove surface contaminants and lubricating coatings generated during the upsetting process; 4) CNC centerless grinding: The outer diameter of the large and small rods is ground using a CNC grinding machine to meet the dimensional accuracy requirements of subsequent thread processing; 5) Thread rolling: Using a CNC thread rolling machine, the large and small sections of the ground mandrel are rolled into threads in one pass to produce double-threaded threads with the same pitch. 6) Cleaning: Place the threaded core rod semi-finished product into the ultrasonic cleaning line and remove the surface oil stains through ultrasonic cleaning. 7) Heat treatment: Place the semi-finished core rod into a vacuum aging furnace, heat it to 450-550℃, hold it for 8-12 hours, and then cool it in the furnace to make its tensile strength reach more than 1300MPa. 8) Surface treatment: The core rod semi-finished product is subjected to a base treatment, which includes phosphating and sandblasting. Then, an automatic coating machine is used to coat its surface with a molybdenum disulfide coating. The coating thickness is controlled within the range of 5-15μm to obtain the core rod finished product.

[0023] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: The four-die cold heading process forms the head, large rod, small rod, and transition arc under the head of the mandrel in one step, ensuring dimensional consistency and production efficiency; a CNC thread rolling machine forms double-threaded threads of the same pitch on the large and small rods in one pass, improving thread processing efficiency and quality; precise aging heat treatment (450-550℃, 8-12h) ensures the tensile strength of the mandrel reaches over 1300MPa, meeting high-strength requirements; and a molybdenum disulfide coating (5-15μm) effectively controls the coefficient of friction, improves installation stability, and provides good lubrication and wear resistance.

[0024] Furthermore, the manufacturing steps for the nail sleeve are as follows: 1) Preparation of nail sleeve blanks: Select drawn bars or tubes with tensile strength of 500-750MPa; 2) Turning: Turning to form stepped holes to obtain the semi-finished nail sleeve; 3) Cleaning: Cleaning removes surface dirt; 4) Heat treatment: Heat the semi-finished nail sleeve to 500-650℃ and keep it at that temperature for 2-4 hours; then perform local annealing on the upper section at 600-800℃ and roll extrusion strengthening treatment on the lower section to make the nail sleeve form a three-section structure with high strength in the lower section, medium strength in the middle section and low strength in the upper section. 5) Surface treatment: Coating with aluminum coating and molybdenum disulfide coating to obtain the finished nail sleeve.

[0025] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: using drawn bar or tube material (500-750MPa) ensures the initial strength of the nail sleeve; through overall heating (500-650℃, 2-4h) combined with local annealing (600-800℃) and roll extrusion strengthening treatment, the nail sleeve forms a three-section structure with high strength in the lower section, medium strength in the middle section, and low strength in the upper section. Each section plays a supporting, deforming, and expanding role during installation, ensuring that a bell tower-shaped head is formed after riveting, reducing the installation driving force and improving installation stability; coating with aluminum coating and molybdenum disulfide coating improves the corrosion resistance and lubrication performance of the nail sleeve.

[0026] Furthermore, the manufacturing steps for the nail sleeve are as follows: 1) Blank preparation: Select annealed and cold-drawn coiled wire as blank, with a lubricating coating on its surface; 2) Cold heading: Using a cold heading machine and molds of corresponding specifications, the blank is cold-headed in one step to form an inner hole and a stepped hole, resulting in a shaped semi-finished product with a stepped hole. 3) Coating removal: The upset semi-finished product is subjected to vibration polishing and pickling in sequence to remove surface dirt and lubricating coating generated during upseting; 4) Turning and repairing stepped holes: The semi-finished product after the coating is removed is turned to repair the stepped holes and obtain the nail sleeve semi-finished product; 5) Heat treatment: Place the semi-finished nail sleeve into a vacuum furnace and heat it to 450-660℃, hold it at that temperature for 0.5-2 hours, and then cool it in the furnace. 6) CNC centerless grinder: The outer diameter of the nail sleeve semi-finished product is ground using a CNC grinder to provide a precise dimensional reference for subsequent riveting and installation; 7) Cleaning: Place the ground nail sleeve semi-finished product into the ultrasonic cleaning line and remove surface oil stains through ultrasonic cleaning; 8) Surface treatment: The cleaned nail sleeve semi-finished product is subjected to a base treatment, which includes phosphating and sandblasting. Then, an automatic coating machine is used to coat the surface with a molybdenum disulfide coating, with the coating thickness controlled within the range of 5-15μm, to obtain the finished nail sleeve.

[0027] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: the internal hole and stepped hole are processed by cold heading one-time forming process, which has higher material utilization and production efficiency compared with machining; the vacuum heat treatment (450-660℃, 0.5-2h) ensures the strong plasticity matching of the nail sleeve; the outer diameter is ground by CNC centerless grinding, which provides a precise dimensional reference for subsequent riveting and installation, ensuring installation accuracy; the surface is coated with a molybdenum disulfide coating (5-15μm), which improves the lubrication performance and wear resistance of the nail sleeve and reduces the frictional resistance during installation. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 The attached figure is a cross-sectional view of a lightweight, highly corrosion-resistant threaded puller for aviation applications provided by the present invention. Figure 2 The attached figure is an exploded view of a lightweight, highly corrosion-resistant threaded pull pin for aviation applications provided by the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1: like Figure 1 , 2 As shown in the figure, this invention discloses a lightweight, highly corrosion-resistant threaded snap pin for aviation applications. It includes a core rod 1, a ring 5, and a pin sleeve 2, a pin body 3, and a drive nut 4, which are threadedly connected to the core rod 1 from bottom to top. The ring 5 is placed within a stepped hole in the pin sleeve 2 and contacts the guide cone at the bottom of the pin body 3. Both the core rod 1 and the pin body 3 are made of titanium alloy. The pin sleeve 2 is made of pure titanium or a titanium alloy. In this embodiment, the titanium alloy is any one of TB9, TC4, and TA1, but is not limited to the listed titanium alloys. The pin body 3 is made of TC4. The ring 5 is made of polyoxymethylene (POM). This invention achieves an overall lightweight design for the threaded snap pin, reducing weight by more than 10% compared to traditional steel, which helps improve aircraft fuel efficiency and payload. Simultaneously, titanium alloy has excellent corrosion resistance, enabling it to adapt to highly corrosive environments such as marine atmospheres, significantly extending the service life of the snap pin.

[0032] To further optimize the technical solution of the present invention, the nail body 3 and the core rod 1, as well as the core rod 1 and the drive nut 4, are both fitted with double-threaded connections. The double-threaded connection must ensure that the phase difference between the two helical lines is 180°. In this way, under the same pitch conditions, the lead of the double-threaded connection is twice that of the single-threaded connection, thereby improving the thread processing efficiency (double the thread rolling / tapping efficiency) and installation efficiency (half the number of tightening turns), effectively reducing manufacturing costs and assembly time.

[0033] Specifically, the end face of the nail head of the nail body 3 that contacts the drive nut 4 is a smooth plane, which eliminates the wringing grooves such as cross grooves or flower grooves on the traditional pull nail head, thereby eliminating the recessed gaps left on the surface of the nail head after riveting, ensuring a flat surface after installation, which is beneficial to the aerodynamics of the aircraft shape, and at the same time eliminating the stress concentration and corrosion risk caused by the recessed area.

[0034] This invention also discloses a manufacturing method for the lightweight, highly corrosion-resistant threaded pull pin for aviation applications as described above, comprising manufacturing the pin body 3, drive nut 4, core rod 1, and pin sleeve 2 separately. By manufacturing the pin body 3, drive nut 4, core rod 1, and pin sleeve 2 independently, each component can employ its own optimal processing technology and heat treatment parameters, ensuring the dimensional accuracy and mechanical properties of each component. This provides a high-quality component foundation for subsequent assembly, improving the finished product qualification rate and product consistency.

[0035] Specifically, the manufacturing steps for nail body 3 are as follows: 1) Blank preparation: Select TC4 titanium alloy wire; 2) Upsetting: The TC4 titanium alloy wire is placed in a warm upsetting machine, and the nail head, shank, and transition arc at the connection between the nail head and shank are warm upset in one step using the corresponding mold to obtain a semi-finished nail body; 3) Cleaning: The forged blank is vibrated and polished to remove surface dirt and raw material coatings generated during upsetting; 4) Machining: Machining the nail head; Drilling a tapping hole in the nail body using a drilling machine; 5) Tapping: Use a double-starting thread tap with the same pitch to machine a double-starting thread on the inner wall of the ground nail body semi-finished product; 6) CNC centerless grinder: The heat-treated semi-finished product is placed on a centerless grinder to grind the outer diameter of the rod. 7) Heat treatment: For the first heat treatment, the cleaned nail semi-finished product is subjected to solution heat treatment, heated to 900-980℃, held for 30-60 minutes, and then water-cooled; for the second heat treatment, the air-cooled nail semi-finished product is placed in a vacuum aging furnace at 480℃-580℃ for 4-6 hours, and then cooled with the furnace. 8) Surface treatment: The nail body semi-finished product is passivated or coated with aluminum to obtain the finished product.

[0036] Specifically, the manufacturing steps for drive nut 4 are as follows: 1) Preparation of drive nut blank: Select hexagonal alloy steel of predetermined specifications as the blank; 2) Machining: Drilling equipment is used to machine the pilot hole in the hexagonal alloy steel billet; 3) Heat treatment: Solution heat treatment: Place the semi-finished drive nut in a vacuum solution furnace at 850℃-900℃ and hold for 45min-60min, then oil cool; Tempering treatment: Place the semi-finished drive nut after solution heat treatment in a vacuum furnace at 350℃-400℃ and hold for 2h-3h, then air cool, so that its hardness reaches 45-55HRC. 4) Use a double-starting, same-pitch thread tap to machine a double-starting internal thread on the nut semi-finished product; 5) Surface treatment: The heat-treated drive nut semi-finished product is then subjected to nickel plating, zinc plating, or chromium plating to obtain the finished product.

[0037] Specifically, the manufacturing steps for core rod 1 are as follows: 1) Raw material: TB9 titanium alloy wire is selected as the raw material. TB9 titanium alloy wire is in the solution heat-treated state, with a tensile strength ≥1000MPa and a lubricating coating on the surface. 2) Cold heading: Place the TB9 titanium alloy wire in a four-die cold heading machine, and use dies of the corresponding specifications to cold head the head, large rod, small rod and transition arc at the head rod connection in one step to obtain a semi-finished TB9 titanium alloy core rod with steps. 3) Coating removal: The semi-finished core rod is passed through a vibratory polishing machine and an acid pickling line in sequence to remove surface contaminants and lubricating coatings generated during the upsetting process; 4) CNC centerless grinding: The outer diameter of the large and small rods is ground using a CNC grinding machine to meet the dimensional accuracy requirements of subsequent thread processing; 5) Thread rolling: Using a CNC thread rolling machine, the large and small sections of the ground mandrel are rolled into threads in one pass to produce double-threaded threads with the same pitch. 6) Cleaning: Place the threaded core rod semi-finished product into the ultrasonic cleaning line and remove the surface oil stains through ultrasonic cleaning. 7) Heat treatment: Place the semi-finished core rod into a vacuum aging furnace, heat it to 450-550℃, hold it for 8-12 hours, and then cool it in the furnace to make its tensile strength reach more than 1300MPa. 8) Surface treatment: The core rod semi-finished product is subjected to a base treatment, which includes phosphating and sandblasting. Then, an automatic coating machine is used to coat its surface with a molybdenum disulfide coating. The coating thickness is controlled within the range of 5-15μm to obtain the core rod finished product.

[0038] Specifically, the manufacturing steps for the nail sleeve 2 are as follows: 1) Preparation of nail sleeve blanks: Select drawn bars or tubes with tensile strength of 500-750MPa; 2) Turning: Turning to form stepped holes to obtain the semi-finished nail sleeve; 3) Cleaning: Cleaning removes surface dirt; 4) Heat treatment: Heat the semi-finished nail sleeve to 500-650℃ and keep it at that temperature for 2-4 hours; then perform local annealing on the upper section at 600-800℃ and roll extrusion strengthening treatment on the lower section to make the nail sleeve form a three-section structure with high strength in the lower section, medium strength in the middle section and low strength in the upper section. 5) Surface treatment: Coating with aluminum coating and molybdenum disulfide coating to obtain the finished nail sleeve.

[0039] Example 2: The only difference between this embodiment and Embodiment 1 is the manufacturing method of the nail sleeve 2. The manufacturing steps of the nail sleeve 2 in this embodiment are as follows: 1) Blank preparation: Select annealed and cold-drawn coiled wire as blank, with a lubricating coating on its surface; 2) Cold heading: Using a cold heading machine and molds of corresponding specifications, the blank is cold-headed in one step to form an inner hole and a stepped hole, resulting in a shaped semi-finished product with a stepped hole. 3) Coating removal: The upset semi-finished product is subjected to vibration polishing and pickling in sequence to remove surface dirt and lubricating coating generated during upseting; 4) Turning and repairing stepped holes: The semi-finished product after the coating is removed is turned to repair the stepped holes and obtain the nail sleeve semi-finished product; 5) Heat treatment: Place the semi-finished nail sleeve into a vacuum furnace and heat it to 450-660℃, hold it at that temperature for 0.5-2 hours, and then cool it in the furnace. 6) CNC centerless grinder: The outer diameter of the nail sleeve semi-finished product is ground using a CNC grinder to provide a precise dimensional reference for subsequent riveting and installation; 7) Cleaning: Place the ground nail sleeve semi-finished product into the ultrasonic cleaning line and remove surface oil stains through ultrasonic cleaning; 8) Surface treatment: The cleaned nail sleeve semi-finished product is subjected to a base treatment, which includes phosphating and sandblasting. Then, an automatic coating machine is used to coat the surface with a molybdenum disulfide coating, with the coating thickness controlled within the range of 5-15μm, to obtain the finished nail sleeve.

[0040] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0041] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lightweight, highly corrosion-resistant threaded pull pin for aviation applications, comprising a core rod, a ring, and a pin sleeve, a pin body, and a drive nut, which are sequentially sleeved on the core rod from bottom to top and threadedly connected, wherein the ring is placed within a stepped hole in the pin sleeve and contacts a guide cone at the bottom of the pin body, characterized in that... Both the core rod and the nail body are made of titanium alloy, the nail sleeve is made of pure titanium or titanium alloy, and the ring is made of polyoxymethylene.

2. The lightweight, highly corrosion-resistant threaded pull pin for aviation use according to claim 1, characterized in that, The nail body and the core rod, as well as the core rod and the drive nut, are both fitted with double-threaded connections.

3. The lightweight, highly corrosion-resistant threaded pull pin for aviation use according to claim 1, characterized in that, The end face of the nail head that contacts the drive nut is a smooth plane.

4. The lightweight, highly corrosion-resistant threaded pull pin for aviation use according to claim 1, characterized in that, The titanium alloy material is any one of TB9, TC4, and TA1.

5. A method for manufacturing a lightweight, highly corrosion-resistant threaded pull pin for aviation as described in any one of claims 1-4, characterized in that, The nail body, drive nut, core rod, and nail sleeve are manufactured separately.

6. The manufacturing method according to claim 5, characterized in that, The manufacturing steps for the nail body are as follows: 1) Blank preparation: Select TC4 titanium alloy wire; 2) Upsetting: The TC4 titanium alloy wire is placed in a warm upsetting machine, and the nail head, shank, and transition arc at the connection between the nail head and shank are warm upset in one step using the corresponding mold to obtain a semi-finished nail body; 3) Cleaning: The forged blank is vibrated and polished to remove surface dirt and raw material coatings generated during upsetting; 4) Machining: Machining the nail head; Drilling a tapping hole in the nail body using a drilling machine; 5) Tapping: Use a double-starting thread tap with the same pitch to machine a double-starting thread on the inner wall of the ground nail body semi-finished product; 6) CNC centerless grinder: The heat-treated semi-finished product is placed on a centerless grinder to grind the outer diameter of the rod. 7) Heat treatment: For the first heat treatment, the cleaned nail semi-finished product is subjected to solution heat treatment, heated to 900-980℃, held for 30-60 minutes, and then water-cooled; for the second heat treatment, the air-cooled nail semi-finished product is placed in a vacuum aging furnace at 480℃-580℃ for 4-6 hours, and then cooled with the furnace. 8) Surface treatment: The nail body semi-finished product is passivated or coated with aluminum to obtain the finished product.

7. The manufacturing method according to claim 5, characterized in that, The manufacturing steps for the drive nut are as follows: 1) Preparation of drive nut blank: Select hexagonal alloy steel of predetermined specifications as the blank; 2) Machining: Drilling equipment is used to machine the pilot hole in the hexagonal alloy steel billet; 3) Heat treatment: Solution heat treatment: Place the semi-finished drive nut in a vacuum solution furnace at 850℃-900℃ and hold for 45min-60min, then oil cool; Tempering treatment: Place the semi-finished drive nut after solution heat treatment in a vacuum furnace at 350℃-400℃ and hold for 2h-3h, then air cool, so that its hardness reaches 45-55HRC. 4) Use a double-starting, same-pitch thread tap to machine a double-starting internal thread on the nut semi-finished product; 5) Surface treatment: The heat-treated drive nut semi-finished product is then subjected to nickel plating, zinc plating, or chromium plating to obtain the finished product.

8. The manufacturing method according to claim 5, characterized in that, The manufacturing steps of the core rod are as follows: 1) Raw material: TB9 titanium alloy wire is selected as the raw material. TB9 titanium alloy wire is in the solution heat-treated state, with a tensile strength ≥1000MPa and a lubricating coating on the surface. 2) Cold heading: Place the TB9 titanium alloy wire in a four-die cold heading machine, and use dies of the corresponding specifications to cold head the head, large rod, small rod and transition arc at the head rod connection in one step to obtain a semi-finished TB9 titanium alloy core rod with steps. 3) Coating removal: The semi-finished core rod is passed through a vibratory polishing machine and an acid pickling line in sequence to remove surface contaminants and lubricating coatings generated during the upsetting process; 4) CNC centerless grinding: The outer diameter of the large and small rods is ground using a CNC grinding machine to meet the dimensional accuracy requirements of subsequent thread processing; 5) Thread rolling: Using a CNC thread rolling machine, the large and small sections of the ground mandrel are rolled into threads in one pass to produce double-threaded threads with the same pitch. 6) Cleaning: Place the threaded core rod semi-finished product into the ultrasonic cleaning line and remove the surface oil stains through ultrasonic cleaning. 7) Heat treatment: Place the semi-finished core rod into a vacuum aging furnace, heat it to 450-550℃, hold it for 8-12 hours, and then cool it in the furnace to make its tensile strength reach more than 1300MPa. 8) Surface treatment: The core rod semi-finished product is subjected to a base treatment, which includes phosphating and sandblasting. Then, an automatic coating machine is used to coat its surface with a molybdenum disulfide coating. The coating thickness is controlled within the range of 5-15μm to obtain the core rod finished product.

9. A manufacturing method according to claim 5, characterized in that, The manufacturing steps for the nail sleeve are as follows: 1) Preparation of nail sleeve blanks: Select drawn bars or tubes with tensile strength of 500-750MPa; 2) Turning: Turning to form stepped holes to obtain the semi-finished nail sleeve; 3) Cleaning: Cleaning removes surface dirt; 4) Heat treatment: Heat the semi-finished nail sleeve to 500-650℃ and keep it at that temperature for 2-4 hours; then perform local annealing on the upper section at 600-800℃ and roll extrusion strengthening treatment on the lower section to make the nail sleeve form a three-section structure with high strength in the lower section, medium strength in the middle section and low strength in the upper section. 5) Surface treatment: Coating with aluminum coating and molybdenum disulfide coating to obtain the finished nail sleeve.

10. A manufacturing method according to claim 5, characterized in that, The manufacturing steps for the nail sleeve are as follows: 1) Blank preparation: Select annealed and cold-drawn coiled wire as blank, with a lubricating coating on its surface; 2) Cold heading: Using a cold heading machine and molds of corresponding specifications, the blank is cold-headed in one step to form an inner hole and a stepped hole, resulting in a shaped semi-finished product with a stepped hole. 3) Coating removal: The upset semi-finished product is subjected to vibration polishing and pickling in sequence to remove surface dirt and lubricating coating generated during upseting; 4) Turning and repairing stepped holes: The semi-finished product after the coating is removed is turned to repair the stepped holes and obtain the nail sleeve semi-finished product; 5) Heat treatment: Place the semi-finished nail sleeve into a vacuum furnace and heat it to 450-660℃, hold it at that temperature for 0.5-2 hours, and then cool it in the furnace. 6) CNC centerless grinder: The outer diameter of the nail sleeve semi-finished product is ground using a CNC grinder to provide a precise dimensional reference for subsequent riveting and installation; 7) Cleaning: Place the ground nail sleeve semi-finished product into the ultrasonic cleaning line and remove surface oil stains through ultrasonic cleaning; 8) Surface treatment: The cleaned nail sleeve semi-finished product is subjected to a base treatment, which includes phosphating and sandblasting. Then, an automatic coating machine is used to coat the surface with a molybdenum disulfide coating, with the coating thickness controlled within the range of 5-15μm, to obtain the finished nail sleeve.

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