Multi-layer structure high-strength rivet with stress dispersion function and preparation method of multi-layer structure high-strength rivet

Abstract

The invention relates to the technical field of rivets, and discloses a multilayer-structure high-strength rivet with a stress dispersion function and a preparation method thereof.The multilayer-structure high-strength rivet comprises a rivet core, a rivet body is arranged on the outer wall of the rivet core, located at the center layer position and used for bearing tension and enabling the rivet body to deform, and one end of the rivet core is a rivet head and located on the outer side of one end of the rivet body; the rivet body is used for providing an acting point and conveniently applying tensile force, a first ring groove is formed in the lower side of the rivet body and used for relieving stress when the rivet body deforms, and a plurality of second ring grooves are formed in the rivet body corresponding to the connecting piece and used for conveniently applying pressure to generate internal expansion of the rivet body and increasing the friction force between the rivet body and the connecting piece. Stress can be relieved during deformation through the first ring groove, meanwhile, the rivet body can expand inwards under pressure through the second ring grooves so as to increase the friction force between the rivet body and a connecting piece, the limiting cap can limit the insertion depth of the rivet core, the rivet core makes contact with the connected piece to achieve the positioning and supporting effects, and therefore the effects of stress dispersion and high-strength connection are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of rivets, in particular to a multi-layer high-strength rivet with a stress dispersion function and a preparation method thereof. Background Art

[0002] In the modern industrial field, the performance requirements for connection structures are constantly increasing. With the advancement of science and technology and the development of various industries, complex working environments and high-load conditions have put forward higher requirements for rivets. In the fields of machinery manufacturing, aerospace, and automobile industry, the connection structure needs to withstand huge tension, pressure, and vibration. In order to ensure the safe operation and long-term stability of the equipment, rivets need to have high strength and good stress dispersion function. In the connection of some key parts, such as the connection between the aircraft wing and the fuselage, the connection of the automobile chassis, etc., the performance of the rivet is directly related to the reliability of the entire structure, and it is necessary to ensure that the rivet needs to maintain stable performance in extreme temperature changes and high vacuum environments, and the rivet needs to have good corrosion resistance to prevent corrosion by chemical substances.

[0003] However, with current technology, when traditional rivets are under load, the stress distribution is relatively concentrated, which can easily generate excessive stress in local areas and make it difficult to relieve the stress. At the same time, they cannot expand in the connecting parts, causing local areas to be subjected to excessive stress, making the rivets more likely to break, thereby reducing the reliability and safety of the connection structure. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a multi-layer high-strength rivet with stress dispersion function and a preparation method thereof, which solves the problems of being unable to expand in the connecting piece, difficulty in relieving stress, and reduced reliability and safety of the connecting structure.

[0005] To achieve the above purpose, the present invention is implemented through the following technical solutions: a multi-layer high-strength rivet with stress dispersion function, including a nail core, the outer wall of the nail core is provided with a rivet body, which is located at the center layer position and is used to withstand tension and deform the rivet body. One end of the nail core is a nail head, which is located outside one end of the rivet body and is used to provide a fulcrum for applying tension. A first annular groove is provided inside the lower side of the rivet body to ensure that the stress is relieved when the rivet body is deformed. A plurality of second annular grooves are provided inside the rivet body and the corresponding connecting piece to facilitate the internal expansion of the rivet body when pressure is applied, thereby increasing the friction between the rivet body and the connecting piece. A limiting cap is provided at the other end of the rivet body to limit the insertion depth of the nail core and to contact with the surface of the connected piece to play a role in positioning and supporting. A sealing groove is provided on the surface between the limiting cap and the surface of the connected piece, and the sealing groove is used to place a sealing material to enhance the sealing of the connection. A rubber sleeve is provided on the outer surface of the limiting cap, and the rubber sleeve can ensure that the rivet adapts to different environmental changes.

[0006] A method for preparing a multi-layer high-strength rivet with a stress dispersion function comprises the following steps: S1: Selection of high-strength materials. Prepare the raw materials for each component according to the given mass fraction. The nail core and nail head are made of low-alloy steel, and the rivet body and limit cap are made of titanium-aluminum alloy. S2: Manufacturing of nail core and nail head: various metal raw materials of low alloy steel are put into a furnace to melt into a uniform liquid alloy, and an inert gas is introduced into the furnace to protect the alloy from oxidation. The liquid alloy is then injected into a mold to produce the initial shape of the nail core and nail head. The nail core and nail head are then processed by turning and milling, and then quenched, and nitrogen is introduced during quenching; S3: Manufacturing of rivet body and limit cap. Put the metal raw materials of titanium aluminum alloy into a special furnace and melt them into a uniform liquid alloy. Inert gas can also be introduced for protection. Then, the preliminary shapes of the rivet body and limit cap are made by casting. Holes are drilled on the rivet body and limit cap. The first ring groove, the second ring groove and the sealing groove are machined inside the rivet body by cutting. S4: Assemble the rivets. After ensuring the dimensional accuracy of each component, clean each component to remove surface oil, impurities and oxide scale. Insert the nail core into the corresponding hole of the rivet body to ensure that the axis of the nail core and the rivet body coincide. Press the nail core into the rivet body by a press. Then, fix the limit cap at one end of the rivet body by welding. Then, put the matching rubber sleeve on the limit cap. Then, place a sealing ring in the sealing groove of the limit cap. At the same time, fix the nail core and the nail head at the other end of the rivet body by welding. S5: Surface treatment: Surface treatment of each part of the rivet, and galvanizing of the outer surface of the rivet; S6: Shot peening, by high-speed spraying of steel shots and other particles, the surface of the rivet is shot peened. Shot peening can produce compressive stress on its surface and form a dense reinforcement layer on the surface to improve the surface hardness and wear resistance.

[0007] Preferably, the S1 medium-low alloy steel includes 0.45-0.55 parts of carbon, 1.7-2.1 parts of manganese, 1.6-2.0 parts of silicon, 1.2-1.6 parts of chromium, 185-195 parts of iron and 0.8-1.5 parts of nickel, and the titanium-aluminum alloy includes 5.5-6.8 parts of aluminum, 1.5-2.2 parts of vanadium, 2.1-3.5 parts of copper, 6.4-7.5 parts of manganese, 2.7-3.7 parts of titanium, 0.5-0.8 parts of niobium, 0.07-0.1 parts of carbon, 3.6-4.7 parts of chromium and 180-200 parts of iron.

[0008] Preferably, the temperature of the S2 medium and low alloy steel melting furnace is 1500℃-1650℃ until it melts into liquid alloy, the inert gas is nitrogen, and the introduction rate is 5-10 cubic meters per minute, and then it is injected into the mold for molding and cooled to obtain a preliminary shape, the quenching is slowly heated to the quenching temperature at a rate of 10-15℃ per minute, the quenching temperature is 800℃-900℃, and when the temperature reaches the quenching temperature, the temperature is maintained for 30-60 minutes, and nitrogen is introduced into the quenching furnace to maintain a nitrogen atmosphere in the furnace. The nitrogen flow rate can be controlled at 5-10 liters per minute, and it is placed in quenching medium water for cooling.

[0009] Preferably, the melting temperature of the titanium aluminum alloy in S3 is 1200°C-1400°C, the inert gas is argon, and its introduction rate is controlled at 3-8 cubic meters per minute, the drilling speed of the drill hole is 500-1500 revolutions per minute, and the feed rate is 0.1-0.3 mm per revolution.

[0010] Preferably, in the cleaning of S4, for oil stains, an organic solvent-based cleaner is used, the parts are soaked in the cleaner, and then lightly scrubbed with a brush to remove the oil stains on the surface. For impurities, compressed air is used to blow and wipe them to remove them. For oxide scale, sandpaper or a wire brush is used to gently polish and remove the surface oxide layer. The welding adopts argon arc welding.

[0011] Preferably, the galvanizing step in S5 is treated as degreasing, pickling, galvanizing and passivation, the degreasing alkaline degreasing agent removes oil stains on the surface, the temperature of the alkaline degreasing agent is 50-70°C, and the immersion time is 10-30 minutes, the pickling removes surface oxide scale and rust by dilute hydrochloric acid, and the immersion time is 5-15 minutes, the temperature of the galvanizing solution in the galvanizing is 40-60, the pH value is 12-14, the rivet body is used as the cathode, placed in the galvanizing tank, connected to the power supply, and the anode uses a zinc plate, the current density is between 1-5A / dm², and the time is 10-30 minutes.

[0012] Preferably, in S6, the shot peening pressure is 0.2-0.8 MPa, the shot peening time is 30 seconds to 2 minutes, the distance between the spray gun and the rivet surface is 100-300 mm, and the angle between the spray gun and the rivet surface is 30°-90°.

[0013] The present invention provides a multi-layer high-strength rivet with stress dispersion function and a preparation method thereof. It has the following beneficial effects: 1. The present invention can relieve stress during deformation through the first annular groove, and at the same time, multiple second annular grooves can make the rivet body expand under pressure to increase the friction with the connecting piece. The limit cap can limit the insertion depth of the nail core and contact with the connected piece to play a positioning and supporting role, thereby achieving the effect of stress dispersion and high-strength connection.

[0014] 2. In the galvanizing treatment, the present invention first uses an alkaline degreasing agent to soak and remove surface oil stains, then soaks in dilute hydrochloric acid to remove oxide scale and rust, and then galvanizes in the galvanizing solution with the rivet body as the cathode and the zinc plate as the anode, thereby removing impurities on the rivet surface to ensure the subsequent treatment effect, forming a uniform galvanized layer on the rivet surface, playing an anti-corrosion protection role and improving the appearance quality. At the same time, the subsequent passivation treatment creates good conditions to extend the service life of the rivet in different environments.

[0015] 3. The present invention processes the surface of the rivet by high-speed spraying of steel shots and other particles through shot peening, which can generate compressive stress on the surface of the rivet and form a dense reinforcement layer, thereby achieving the effect of improving the surface hardness and wear resistance of the rivet, enhancing the wear resistance of the rivet during use, and extending its service life. At the same time, the surface compressive stress can offset part of the tensile stress during use, improve the fatigue strength and stress corrosion resistance of the rivet, and can remove impurities and oxide scale on the surface of the rivet, thereby improving the appearance quality of the rivet and improving the use quality of the rivet. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A three-dimensional diagram of a multi-layer high-strength rivet with stress dispersion function according to the present invention; Figure 2 It is a cross-sectional view of a multi-layer high-strength rivet with stress dispersion function of the present invention; Figure 3 The present invention is a flow chart of a method for preparing a multi-layer high-strength rivet with stress dispersion function.

[0017] Among them, 1. nail core; 2. rivet body; 3. nail head; 4. first ring groove; 5. second ring groove; 6. limit cap; 7. rubber sleeve; 8. sealing groove. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Please see attached Figure 1 - Attachment Figure 3The embodiment of the present invention provides a multi-layer high-strength rivet with stress dispersion function and a preparation method thereof, comprising a nail core 1, a rivet body 2 is arranged on the outer wall of the nail core 1, which is located at the center layer position and is used to withstand the tensile force to deform the rivet body 2, one end of the nail core 1 is a nail head 3, which is located outside one end of the rivet body 2 and is used to provide a fulcrum for applying tensile force, a first annular groove 4 is provided inside the lower side of the rivet body 2 to ensure that the stress is relieved when the rivet body 2 is deformed, a plurality of second annular grooves 5 are provided inside the rivet body 2 and the corresponding connecting piece to facilitate the application of pressure so that the rivet body 2 expands internally and increases the friction between the rivet body 2 and the connecting piece, a limiting cap 6 is provided at the other end of the rivet body 2 to limit the insertion depth of the nail core 1 and to contact with the surface of the connected piece to play a role of positioning and supporting, a sealing groove 8 is provided on the surface between the limiting cap 6 and the surface of the connected piece, and the sealing groove 8 is used to place a sealing material to enhance the sealing of the connection, and a rubber sleeve 7 is provided on the outer surface of the limiting cap 6, which can ensure that the rivet adapts to different environmental changes.

[0020] Specifically, the first annular groove 4 inside the rivet body can relieve stress during deformation, and the multiple second annular grooves 5 can make the rivet body 2 expand under pressure to increase the friction with the connecting piece. The limit cap 6 can limit the insertion depth of the nail core 1 and contact with the connected piece to play a positioning and supporting role. The sealing groove 8 on its surface is filled with sealing material to enhance the sealing of the connection. The rubber sleeve 7 on the outer surface ensures that the rivet can adapt to different environmental changes, thereby achieving stress dispersion, high-strength connection, good sealing performance and strong adaptability. It can meet the connection requirements in various complex working environments in the fields of industry, construction, electronic equipment, etc.

[0021] A method for preparing a multi-layer high-strength rivet with a stress dispersion function comprises the following steps: S1: Selection of high-strength materials. Prepare the raw materials for each component according to the given mass fraction. The nail core and nail head are made of low-alloy steel, and the rivet body and limit cap are made of titanium-aluminum alloy. S2: Manufacturing of nail core and nail head: various metal raw materials of low alloy steel are put into a furnace to melt into a uniform liquid alloy, and an inert gas is introduced into the furnace to protect the alloy from oxidation. The liquid alloy is then injected into a mold to produce the initial shape of the nail core and nail head. The nail core and nail head are then processed by turning and milling, and then quenched, and nitrogen is introduced during quenching; S3: Manufacturing of rivet body and limit cap. Put the metal raw materials of titanium aluminum alloy into a special furnace and melt them into a uniform liquid alloy. Inert gas can also be introduced for protection. Then, the preliminary shapes of the rivet body and limit cap are made by casting. Holes are drilled on the rivet body and limit cap. The first ring groove, the second ring groove and the sealing groove are machined inside the rivet body by cutting. S4: Assemble the rivets. After ensuring the dimensional accuracy of each component, clean each component to remove surface oil, impurities and oxide scale. Insert the nail core into the corresponding hole of the rivet body to ensure that the axis of the nail core and the rivet body coincide. Press the nail core into the rivet body by a press. Then, fix the limit cap at one end of the rivet body by welding. Then, put the matching rubber sleeve on the limit cap. Then, place a sealing ring in the sealing groove of the limit cap. At the same time, fix the nail core and the nail head at the other end of the rivet body by welding. S5: Surface treatment: Surface treatment of each part of the rivet, and galvanizing of the outer surface of the rivet; S6: Shot peening, by high-speed spraying of steel shots and other particles, the surface of the rivet is shot peened. Shot peening can produce compressive stress on its surface and form a dense reinforcement layer on the surface to improve the surface hardness and wear resistance.

[0022] S1 medium and low alloy steel includes carbon: 0.45-0.55 parts, manganese: 1.7-2.1 parts, silicon: 1.6-2.0 parts, chromium: 1.2-1.6 parts, iron: 185-195 parts and nickel: 0.8-1.5 parts. Titanium-aluminum alloy includes aluminum: 5.5-6.8 parts, vanadium: 1.5-2.2 parts, copper: 2.1-3.5 parts, manganese: 6.4-7.5 parts, titanium: 2.7-3.7 parts, niobium: 0.5-0.8 parts, carbon: 0.07-0.1 parts, chromium: 3.6-4.7 parts, and iron: 180-200 parts.

[0023] Specifically, low alloy steel has high strength, hardness and toughness, good hardenability and machinability, good corrosion resistance and oxidation resistance, and is suitable for manufacturing rivet cores and rivet heads that withstand heavy loads and work in certain corrosive environments. Titanium aluminum alloy has high strength, high toughness, good corrosion resistance and high temperature performance, and is suitable for manufacturing rivet bodies and limit caps of rivets. It can withstand greater stress and work in complex environments, and at the same time has a lighter weight and good mechanical properties.

[0024] The temperature of the melting furnace for S2 medium and low alloy steel is 1500℃-1650℃ until it melts into liquid alloy. The inert gas is nitrogen, and the introduction rate is 5-10 cubic meters per minute. It is then injected into the mold for molding and cooled to obtain a preliminary shape. The quenching is slowly heated to the quenching temperature at a rate of 10-15℃ per minute. The quenching temperature is 800℃-900℃. When the temperature reaches the quenching temperature, the temperature is maintained for 30-60 minutes. Nitrogen is introduced into the quenching furnace to maintain a nitrogen atmosphere in the furnace. The nitrogen flow rate can be controlled at 5-10 liters per minute and placed in quenching medium water for cooling.

[0025] Specifically, the temperature control can make various metal raw materials fully melted to form a uniform liquid alloy. Different metal elements fuse with each other at high temperature to form a stable alloy structure. At the same time, high temperature can also volatilize impurities in the metal or react with other elements to form easily removable compounds, thereby improving the purity of the alloy. A stable inert atmosphere is formed in the furnace, which effectively prevents the liquid alloy from oxidizing when it comes into contact with oxygen in the air at high temperature. Slowly increasing the temperature during quenching can make the internal temperature of the nail core and the nail head uniform, avoiding deformation or cracking caused by thermal stress caused by temperature gradient. Keeping the material at the quenching temperature for a certain period of time allows the material to be fully austenitized, and prepares the organization for subsequent rapid cooling, so that the rivet can withstand greater loads during use. In the quenching process, the nitrogen environment further prevents oxidation during the cooling process. Water as a quenching medium can quickly cool the alloy, allowing the martensite and other strengthening organizations to be fully formed.

[0026] The melting temperature of titanium aluminum alloy in S3 is 1200℃-1400℃, the inert gas is argon, the introduction speed is controlled at 3-8 cubic meters per minute, the drilling speed is 500-1500 revolutions per minute, and the feed speed is 0.1-0.3 mm per revolution.

[0027] Specifically, the melting temperature of aluminum alloy is 1200℃-1400℃, which can ensure the uniform mixing of elements such as aluminum, vanadium, copper, manganese, titanium, niobium, carbon, chromium, and iron, providing high-quality liquid alloy for subsequent processing, helping to remove impurities and gases in the alloy, and improving the purity and performance of the alloy. The introduction of argon gas can keep the chemical composition of titanium-aluminum alloy stable and avoid impurities and performance degradation caused by oxidation and nitridation.

[0028] For cleaning in S4, for oil stains, use an organic solvent-based cleaner, soak the parts in the cleaner, and then gently scrub them with a brush to remove the oil stains on the surface. For impurities, use compressed air to blow and wipe them to remove them. For oxide scale, use sandpaper or a wire brush to gently grind to remove the surface oxide layer. TIG welding is used for welding.

[0029] Specifically, through cleaning, impurities on the surface can be effectively removed. After cleaning, the surface of the component becomes clean and free of oil residue, ensuring the firmness of welding and the effect of surface treatment. At the same time, argon arc welding can form a stable arc and protective gas atmosphere during the welding process. Using argon arc welding to weld riveted components can obtain firm and beautiful welds with high welding quality, smooth weld surface, and no defects such as pores and slag inclusions.

[0030] The galvanizing steps in S5 are degreasing, pickling, galvanizing and passivation. Degreasing uses alkaline degreasing agent to remove oil stains on the surface. The temperature of the alkaline degreasing agent is 50-70℃ and the immersion time is 10-30 minutes. Pickling uses dilute hydrochloric acid to remove surface oxide scale and rust. The immersion time is 5-15 minutes. The temperature of the galvanizing solution in galvanizing is 40-60, and the pH value is 12-14. The rivet body is used as the cathode and placed in the galvanizing tank. The power supply is connected. The anode uses a zinc plate. The current density is between 1-5A / dm² and the time is 10-30 minutes.

[0031] Specifically, through degreasing. The removal of oil stains can make the subsequent processing steps better, improving the quality and effect of surface treatment. Pickling with dilute hydrochloric acid can remove the oxide scale and rust on the surface of the rivet body. After pickling, the fresh metal matrix is ​​exposed on the surface of the rivet body, providing a good foundation for galvanizing. At the same time, the pickling time is 5-15 minutes, which can effectively remove the oxide scale and rust in a short time, while avoiding damage to the rivet body caused by excessive pickling. After galvanizing, the zinc layer forms a protective film on the surface of the rivet body, which can effectively prevent the rivet body from being corroded in the atmospheric environment. Zinc has good corrosion resistance and can play a protective role even in a humid environment. The subsequent passivation can form a more stable protective film on the surface of the galvanized layer. The passivation solution is usually a chromate or phosphate solution, which can react chemically with the galvanized layer to form a dense passivation film, and improve the corrosion resistance and decorativeness of the galvanized layer, making the rivet body surface smoother and more beautiful.

[0032] In S6, the shot peening pressure is 0.2-0.8MPa, the shot peening time is 30 seconds to 2 minutes, the distance between the spray gun and the rivet surface is 100-300mm, and the angle between the spray gun and the rivet surface is 30°-90°.

[0033] Specifically, shot peening causes plastic deformation on the rivet surface, forming a cold-work hardened layer, which significantly increases the surface hardness. This makes the rivet more resistant to wear and scratches during use, extending its service life. The shot peening process also introduces compressive stress on the rivet surface, which can offset some of the tensile stress generated during use, thereby reducing the possibility of fatigue cracks.

[0034] Example 1, in S1, the low alloy steel raw materials are: carbon: 0.45 parts, manganese: 1.7 parts, silicon: 1.6 parts, chromium: 1.2 parts, iron: 185 parts and nickel: 0.8 parts, titanium aluminum alloy raw materials: aluminum is 5.5 parts, vanadium is 1.5 parts, copper is 2.1 parts, manganese is 6.4 parts, titanium is 2.7 parts, niobium is 0.5 parts, carbon is 0.07 parts, chromium is 3.6 parts, iron is 180 parts The temperature of the S2 medium and low alloy steel melting furnace is 1500℃, the nitrogen introduction rate is 5 cubic meters per minute, and the quenching temperature is slowly increased to the quenching temperature at a rate of 10℃ per minute. The quenching temperature is 800℃ and maintained for 30 minutes. Nitrogen is introduced into the quenching furnace to maintain a nitrogen atmosphere in the furnace. The nitrogen flow rate can be controlled at 5 liters per minute, and the quenching medium is water.

[0035] The melting temperature of titanium-aluminum alloy in S3 is 1200°C, the argon gas introduction rate is controlled at 3 cubic meters per minute, the drilling speed is 500 revolutions per minute, and the feed rate is 0.1 mm per revolution.

[0036] In S4, for oil stains, use an organic solvent-based cleaner, soak the parts in the cleaner, and then gently scrub them with a brush to remove the oil stains on the surface. For impurities, use compressed air to blow and wipe them to remove them. For oxide scale, use sandpaper or a wire brush to gently grind to remove the surface oxide layer, and then weld them using argon arc welding.

[0037] The temperature of alkaline degreasing agent in S5 is 50 degrees, the immersion time is 10 minutes, the immersion time of pickling is 5 minutes, the temperature of galvanizing solution in galvanizing is 40 degrees, the pH value is 12, the rivet body is used as cathode, put into the galvanizing tank, connect the power supply, use zinc plate as anode, the current density is between 1A / dm², and the time is 10 minutes.

[0038] In S6, the shot peening pressure is 0.2MPa, the shot peening time is 30 seconds, the distance between the spray gun and the rivet surface is 100mm, and the angle between the spray gun and the rivet surface is 30°. Example 2, in S1, the low alloy steel raw materials are: carbon: 0.45 parts, manganese: 1.7 parts, silicon: 1.6 parts, chromium: 1.2 parts, iron: 185 parts and nickel: 0.8 parts, titanium aluminum alloy raw materials: aluminum is 5.5 parts, vanadium is 1.5 parts, copper is 2.1 parts, manganese is 6.4 parts, titanium is 2.7 parts, niobium is 0.5 parts, carbon is 0.07 parts, chromium is 3.6 parts, iron is 180 parts The temperature of the S2 medium and low alloy steel melting furnace is 1500℃, the nitrogen introduction rate is 5 cubic meters per minute, and the quenching temperature is slowly increased to the quenching temperature at a rate of 10℃ per minute. The quenching temperature is 800℃ and maintained for 30 minutes. Nitrogen is introduced into the quenching furnace to maintain a nitrogen atmosphere in the furnace. The nitrogen flow rate can be controlled at 5 liters per minute, and the quenching medium is water.

[0039] The melting temperature of titanium-aluminum alloy in S3 is 1200°C, the argon gas introduction rate is controlled at 3 cubic meters per minute, the drilling speed is 500 revolutions per minute, and the feed rate is 0.1 mm per revolution.

[0040] In S4, for oil stains, use an organic solvent-based cleaner, soak the parts in the cleaner, and then gently scrub them with a brush to remove the oil stains on the surface. For impurities, use compressed air to blow and wipe them to remove them. For oxide scale, use sandpaper or a wire brush to gently grind to remove the surface oxide layer, and then weld them using argon arc welding.

[0041] The temperature of alkaline degreasing agent in S5 is 50 degrees, the immersion time is 10 minutes, the immersion time of pickling is 5 minutes, the temperature of galvanizing solution in galvanizing is 40 degrees, the pH value is 12, the rivet body is used as cathode, put into the galvanizing tank, connect the power supply, use zinc plate as anode, the current density is between 1A / dm², and the time is 10 minutes.

[0042] In S6, the shot peening pressure is 0.8MPa, the shot peening time is minutes and seconds, the distance between the spray gun and the rivet surface is 300mm, and the angle between the spray gun and the rivet surface is 60°. Table 1 is a comparison table of rivet preparation Stress distribution refers to the stress state inside and at various locations on the surface of the rivet, and rivet appearance refers to the roughness of the outer surface of the rivet.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Multi-layer high-strength rivet with stress dispersion function, characterized in that: The invention comprises a nail core (1), wherein the outer wall of the nail core (1) is provided with a rivet body (2), which is located at a central layer position and is used to withstand tensile force to cause the rivet body (2) to deform; one end of the nail core (1) is a nail head (3), which is located outside one end of the rivet body (2) and is used to provide a force point to facilitate the application of tensile force; a first annular groove (4) is provided inside the lower side of the rivet body (2) to ensure that stress is relieved when the rivet body (2) is deformed; a plurality of second annular grooves (5) are provided inside the rivet body (2) and the connecting piece to facilitate the application of pressure to cause the rivet body (2) to expand internally. The rivet body (2) is provided with a limit cap (6) at the other end thereof, which is used to limit the insertion depth of the rivet core (1) and to contact with the surface of the connected part to play a positioning and supporting role. A sealing groove (8) is provided on the surface between the limit cap (6) and the surface of the connected part. The sealing groove (8) is used to place a sealing material to enhance the sealing of the connection. A rubber sleeve (7) is provided on the outer surface of the limit cap (6). The rubber sleeve (7) can ensure that the rivet can adapt to different environmental changes.

2. A method for preparing a multi-layer high-strength rivet with a stress dispersion function, according to claim 1, wherein the multi-layer high-strength rivet with a stress dispersion function is characterized in that: The following steps are involved: S1: Selection of high-strength materials. Prepare the raw materials for each component according to the given mass fraction. The nail core and nail head are made of low-alloy steel, and the rivet body and limit cap are made of titanium-aluminum alloy. S2: Manufacturing of nail core and nail head: various metal raw materials of low alloy steel are put into a furnace to melt into a uniform liquid alloy, and an inert gas is introduced into the furnace to protect the alloy from oxidation. The liquid alloy is then injected into a mold to produce the initial shape of the nail core and nail head. The nail core and nail head are then processed by turning and milling, and then quenched, and nitrogen is introduced during quenching; S3: Manufacturing of rivet body and limit cap. Put the metal raw materials of titanium aluminum alloy into a special furnace and melt them into a uniform liquid alloy. Inert gas can also be introduced for protection. Then, the preliminary shapes of the rivet body and limit cap are made by casting. Holes are drilled on the rivet body and limit cap. The first ring groove, the second ring groove and the sealing groove are machined inside the rivet body by cutting. S4: Assemble the rivets. After ensuring the dimensional accuracy of each component, clean each component at the same time to remove the oil, impurities and oxide scale on the surface. Insert the nail core into the corresponding hole of the rivet body to ensure that the axis of the nail core and the rivet body coincide. Press the nail core into the rivet body by a press. Then, fix the assembly limit cap at one end of the rivet body by welding, and then put the matching rubber sleeve on the limit cap. Then, put the matching rubber sleeve on the limit cap. Then, place a sealing ring in the sealing groove of the limit cap. At the same time, the nail core and the nail head at the other end of the rivet body are welded and fixed; S5: Surface treatment: Surface treatment of each part of the rivet, and galvanizing of the outer surface of the rivet; S6: Shot peening, by high-speed spraying of steel shots and other particles, the surface of the rivet is shot peened. Shot peening can produce compressive stress on its surface and form a dense reinforcement layer on the surface to improve the surface hardness and wear resistance.

3. The method for preparing a multi-layer high-strength rivet with stress dispersion function according to claim 2, characterized in that: The S1 medium-low alloy steel includes 0.45-0.55 parts of carbon, 1.7-2.1 parts of manganese, 1.6-2.0 parts of silicon, 1.2-1.6 parts of chromium, 185-195 parts of iron and 0.8-1.5 parts of nickel. The titanium-aluminum alloy includes 5.5-6.8 parts of aluminum, 1.5-2.2 parts of vanadium, 2.1-3.5 parts of copper, 6.4-7.5 parts of manganese, 2.7-3.7 parts of titanium, 0.5-0.8 parts of niobium, 0.07-0.1 parts of carbon, 3.6-4.7 parts of chromium and 180-200 parts of iron.

4. The method for preparing a multi-layer high-strength rivet with stress dispersion function according to claim 2, characterized in that: The temperature of the S2 medium and low alloy steel melting furnace is 1500℃-1650℃ until it melts into liquid alloy. The inert gas is nitrogen, and its introduction rate is 5-10 cubic meters per minute. It is then injected into the mold for molding and cooled to obtain a preliminary shape. The quenching is slowly heated to the quenching temperature at a rate of 10-15℃ per minute. The quenching temperature is 800℃-900℃. After the temperature reaches the quenching temperature, the temperature is maintained for 30-60 minutes. Nitrogen is introduced into the quenching furnace to maintain a nitrogen atmosphere in the furnace. The nitrogen flow rate can be controlled at 5-10 liters per minute, and the quenching medium water is placed for cooling.

5. The method for preparing a multi-layer high-strength rivet with stress dispersion function according to claim 2, characterized in that: The melting temperature of the titanium-aluminum alloy in S3 is 1200°C-1400°C, the inert gas is argon, and its introduction speed is controlled at 3-8 cubic meters per minute. The drilling speed of the drilling hole is 500-1500 revolutions per minute, and the feed speed is 0.1-0.3 mm per revolution.

6. The method for preparing a multi-layer high-strength rivet with stress dispersion function according to claim 2, characterized in that: In the S4, for cleaning of oil stains, an organic solvent-based cleaner is used. The parts are soaked in the cleaner and then gently scrubbed with a brush to remove the oil stains on the surface. For impurities, compressed air is used to blow and wipe them away. For oxide scale, sandpaper or a wire brush is used to gently polish and remove the oxide layer on the surface. The welding is performed by argon arc welding.

7. The method for preparing a multi-layer high-strength rivet with stress dispersion function according to claim 2, characterized in that: The galvanizing step in S5 is degreasing, pickling, galvanizing and passivation. The degreasing alkaline degreasing agent removes oil stains on the surface. The temperature of the alkaline degreasing agent is 50-70°C and the immersion time is 10-30 minutes. The pickling removes oxide scale and rust on the surface by dilute hydrochloric acid. The immersion time is 5-15 minutes. The temperature of the galvanizing solution in the galvanizing is 40-60, and the pH value is 12-14. The rivet body is used as a cathode and placed in a galvanizing tank. A power supply is connected. A zinc plate is used as an anode. The current density is between 1-5A / dm² and the time is 10-30 minutes.

8. The method for preparing a multi-layer high-strength rivet with stress dispersion function according to claim 2, characterized in that: In the S6, the shot peening pressure is 0.2-0.8 MPa, the shot peening time is 30 seconds to 2 minutes, the distance between the spray gun and the rivet surface is 100-300 mm, and the angle between the spray gun and the rivet surface is 30°-90°.

Images