Manufacturing method of titanium alloy self-locking nut for aviation

Abstract

The invention discloses a manufacturing method of a titanium alloy self-locking nut for aviation. Comprising the following steps of hexagonal upsetting forming, first-stage solid solution heat treatment, machining forming, second-stage aging heat treatment, fluorescent flaw detection, surface treatment and performance testing. According to the invention, solid solution and aging heat treatment process parameters are optimized, and fluorescence flaw detection and surface treatment technologies are combined, so that the strength and the self-locking performance of the product are improved, and meanwhile, the risks of oxygen pollution and surface defects are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of fasteners, and in particular to a method for manufacturing a titanium alloy self-locking nut for aviation. Background Art

[0002] The level of the aerospace field is an important reflection of a country's comprehensive industrial strength. Key breakthroughs in the aviation field directly affect national defense and national security, and are also one of the key factors for countries to compete in advanced manufacturing and gain commanding heights in the world. In the manufacturing, use and maintenance of aerospace vehicles, most parts are connected by fasteners. Fasteners have a simple structure and reliable anti-vibration and anti-loosening properties, making them one of the most commonly used and most widely used standard parts in aerospace products. The shortcomings of the existing technology are: when the old method is used for processing, the strength after heat treatment cannot be guaranteed, and the self-locking performance test is unstable. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a method for manufacturing titanium alloy self-locking nuts for aviation use, which improves the strength and self-locking performance of the product while reducing the risks of oxygen contamination and surface defects by optimizing the solid solution and aging heat treatment process parameters and combining fluorescent flaw detection and surface treatment technology.

[0004] The purpose of the present invention and the solution of its main technical problems are achieved by adopting the following technical solutions: The present invention provides a method for manufacturing a titanium alloy self-locking nut for aviation, characterized by comprising the following steps: 1) Hexagonal upsetting forming: The hexagonal steel is formed by upsetting at a temperature of 910°C. The first piece of the process is inspected for overheating and overburning, and the warm upsetting heating temperature is controlled at 650°C ~ 730°C.

[0005] 2) The first stage of solution heat treatment: The solution temperature is 890℃~970℃, the solution heat treatment is 900℃~930℃, and the heat preservation time is 20~60 minutes; 3) Machining: Turning flat end face, chamfering, drilling, boring, turning hexagonal end face, chamfering hexagonal, and processing bottom hole; tapping: processing thread, thread stop; turning: turning closing table; closing: the self-locking nut can achieve the self-locking function because there is a closing groove on its cylindrical surface. Under the action of the closing machine, the groove part produces radial closing, thereby changing the shape of the self-locking nut thread, the local thread diameter is reduced, and the nut is closed on the outer cylindrical surface to form a non-circular structure; 4) Second stage aging heat treatment: Aging heat treatment uses titanium alloy water quenching furnace processing, which is carried out in a completely high vacuum environment without oxygen pollution. The processing temperature is 530℃, and the strength requirement is σb=(1100~1250)MPa. 5) Fluorescent flaw detection: Use fluorescence detection to inspect the product surface to ensure there are no defects that affect product performance; 6) Surface treatment: Dry film lubrication is coated with molybdenum disulfide to ensure the lubricity of the product, isolate the product surface from the air, and increase the wear and corrosion resistance of the product.

[0006] 7) Performance test: After passing the performance test, the product design standard requirements are met and the expected effect is achieved, the product manufacturing is completed.

[0007] The hexagonal alloy in step 1) is subjected to upsetting and solutionizing at a temperature of 910°C.

[0008] Compared with the prior art, the present invention has obvious beneficial effects. From the above technical scheme, it can be seen that the titanium alloy fastener is upsetting after heating. The heating temperature needs to be strictly controlled to prevent the product from overheating and oxygen pollution quality defects. The technical conditions of titanium alloy materials require a solid solution temperature of 910°C. The design of upsetting heating parameters should fully consider factors such as forming size quality, die life, overheating, overburning, etc. The process should require the first piece to be overheated and overburned. The warm upsetting heating temperature is optimally controlled at 650°C to 730°C. The general solid solution temperature is between 890°C and 970°C. If the aging temperature and time are fixed, the higher the solid solution temperature, the higher the final strength of the product, but the worse the plastic deformation. Therefore, under the condition of meeting the strength requirements, the solid solution temperature is selected as far as possible to the lower limit, and the holding time, after meeting the time required for the organizational transformation, usually the heating time is longer or shorter, which has little effect. According to the processing experience of other titanium alloy nuts, the solid solution heat treatment is selected at 900°C to 930°C for 20 to 60 minutes. Including turning flat end face, chamfering, drilling, boring, turning hexagonal end face, chamfering hexagonal, and processing bottom hole; tapping: processing thread, thread stop; turning: turning closing table; closing: the self-locking nut can realize the self-locking function because there is a closing groove on its cylindrical surface. Under the action of the closing machine, the groove part produces radial closing, thereby changing the shape of the self-locking nut thread, and the local thread diameter is reduced. The nut is closed on the outer cylindrical surface to form a non-circular structure. This non-circular structure is the locking structure part that produces effective torque. The effective torque is the torsional torque measured during the process of entering the nut under the condition of no axial load. When the bolt and the self-locking nut thread are matched, as the bolt is screwed in, the thread with reduced diameter at the groove produces elastic-plastic deformation and tends to return to the standard thread diameter state. Due to the elastic-plastic deformation recovery process of the self-locking nut, a radial extrusion force is generated on the bolt, which increases the friction resistance between the thread surfaces, thereby playing a locking role. Aging heat treatment uses titanium alloy water quenching furnace processing, which is carried out in a completely high vacuum environment without oxygen pollution. The processing temperature is 530℃, and the strength requirement is σb=(1100~1250)MPa. Fluorescence detection is used to detect the surface of the product to ensure that there are no defects that affect the performance of the product. Molybdenum disulfide is coated with dry film lubrication to ensure the lubricity of the product, isolate the surface of the product from the air, and increase the wear resistance and corrosion resistance of the product. The process parameters of solid solution and aging heat treatment are optimized, and combined with fluorescence flaw detection and surface treatment technology, the strength and self-locking performance of the product are improved, while the risk of oxygen pollution and surface defects is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a process flow chart of the present invention; Figure 2 It is a schematic structural diagram of the nut of the present invention. DETAILED DESCRIPTION

[0010] The specific implementation methods, structures, features and functions of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0011] Example 1 The present invention provides a method for manufacturing a titanium alloy self-locking nut for aviation, characterized by comprising the following steps: 1) Hexagonal upsetting forming: The hexagonal steel is formed by upsetting at a temperature of 910°C. The first piece of the process is inspected for overheating and overburning, and the warm upsetting heating temperature is controlled at 650°C.

[0012] 2) The first stage of solution heat treatment: Solution temperature is 890℃, solution heat treatment is 900℃, and heat preservation is 20 minutes; 3) Machining: Turning flat end face, chamfering, drilling, boring, turning hexagonal end face, chamfering hexagonal, and processing bottom hole; tapping: processing thread, thread stop; turning: turning closing table; closing: the self-locking nut can achieve the self-locking function because there is a closing groove on its cylindrical surface. Under the action of the closing machine, the groove part produces radial closing, thereby changing the shape of the self-locking nut thread, the local thread diameter is reduced, and the nut is closed on the outer cylindrical surface to form a non-circular structure; 4) Second stage aging heat treatment: Aging heat treatment uses titanium alloy water quenching furnace for processing, which is carried out in a completely high vacuum environment without oxygen pollution. The processing temperature is 530℃ and the strength requirement is σb=1100MPa. 5) Fluorescent flaw detection: Use fluorescence detection to inspect the product surface to ensure there are no defects that affect product performance; 6) Surface treatment: Dry film lubrication is coated with molybdenum disulfide to ensure the lubricity of the product, isolate the product surface from the air, and increase the wear and corrosion resistance of the product.

[0013] 7) Performance test: After passing the performance test, the product design standard requirements are met and the expected effect is achieved, the product manufacturing is completed.

[0014] Example 2 The present invention provides a method for manufacturing a titanium alloy self-locking nut for aviation, characterized by comprising the following steps: 1) Hexagonal upsetting forming: The hexagonal steel is formed by upsetting at a temperature of 910°C. The first piece of the process is inspected for overheating and overburning, and the warm upsetting heating temperature is controlled at 690°C.

[0015] 2) The first stage of solution heat treatment: The solution temperature is 930℃, and the solution heat treatment is 915℃ for 40 minutes; 3) Machining: Turning flat end face, chamfering, drilling, boring, turning hexagonal end face, chamfering hexagonal, and processing bottom hole; tapping: processing thread, thread stop; turning: turning closing table; closing: the self-locking nut can achieve the self-locking function because there is a closing groove on its cylindrical surface. Under the action of the closing machine, the groove part produces radial closing, thereby changing the shape of the self-locking nut thread, the local thread diameter is reduced, and the nut is closed on the outer cylindrical surface to form a non-circular structure; 4) Second stage aging heat treatment: Aging heat treatment uses titanium alloy water quenching furnace processing, which is carried out in a completely high vacuum environment without oxygen pollution. The processing temperature is 530℃ and the strength requirement is σb=1100~1250MPa. 5) Fluorescent flaw detection: Use fluorescence detection to inspect the product surface to ensure there are no defects that affect product performance; 6) Surface treatment: Dry film lubrication is coated with molybdenum disulfide to ensure the lubricity of the product, isolate the product surface from the air, and increase the wear and corrosion resistance of the product.

[0016] 7) Performance test: After passing the performance test, the product design standard requirements are met and the expected effect is achieved, the product manufacturing is completed.

[0017] Example 3 The present invention provides a method for manufacturing a titanium alloy self-locking nut for aviation, characterized by comprising the following steps: 1) Hexagonal upsetting forming: The hexagonal steel is formed by upsetting at a temperature of 910°C. The first piece of the process is inspected for overheating and overburning, and the warm upsetting heating temperature is controlled at 730°C.

[0018] 2) The first stage of solution heat treatment: The solution temperature is 970℃, and the solution heat treatment is kept at 930℃ for 60 minutes; 3) Machining: Turning flat end face, chamfering, drilling, boring, turning hexagonal end face, chamfering hexagonal, and processing bottom hole; tapping: processing thread, thread stop; turning: turning closing table; closing: the self-locking nut can achieve the self-locking function because there is a closing groove on its cylindrical surface. Under the action of the closing machine, the groove part produces radial closing, thereby changing the shape of the self-locking nut thread, the local thread diameter is reduced, and the nut is closed on the outer cylindrical surface to form a non-circular structure; 4) Second stage aging heat treatment: Aging heat treatment uses titanium alloy water quenching furnace processing, which is carried out in a completely high vacuum environment without oxygen pollution. The processing temperature is 530℃, and the strength requirement is σb=(1100~1250)MPa. 5) Fluorescent flaw detection: Use fluorescence detection to inspect the product surface to ensure there are no defects that affect product performance; 6) Surface treatment: Dry film lubrication is coated with molybdenum disulfide to ensure the lubricity of the product, isolate the product surface from the air, and increase the wear and corrosion resistance of the product.

[0019] 7) Performance test: After passing the performance test, the product design standard requirements are met and the expected effect is achieved, the product manufacturing is completed.

[0020] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for manufacturing a titanium alloy self-locking nut for aviation, characterized in that: The following steps are involved: 1) Hexagonal upsetting forming: Hexagonal parts are solid solution formed by upsetting. The first piece of the process is inspected for overheating and overburning. The warm upsetting heating temperature is controlled at 650℃~730℃. 2) The first stage of solution heat treatment: The solution temperature is 890℃~970℃; the solution heat treatment is 900℃~930℃, and the temperature is kept at 20~60 minutes; 3) Machining: Turning flat end face, chamfering, drilling, boring, turning hexagonal end face, chamfering hexagonal, and processing bottom hole; tapping: processing thread, thread through and stop; Turning: Turning and closing table; Closing: The self-locking nut can achieve the self-locking function because there is a closing groove on its cylindrical surface. Under the action of the closing machine, the groove part produces radial closing, thereby changing the shape of the self-locking nut thread, the local thread diameter is reduced, and the nut is closed on the outer cylindrical surface to form a non-circular structure; 4) Second stage aging heat treatment: Aging heat treatment uses titanium alloy water quenching furnace processing, which is carried out in a completely high vacuum environment without oxygen pollution. The processing temperature is 530℃ and the strength requirement is σb=1100~1250MPa. 5) Fluorescent flaw detection: Use fluorescence detection to inspect the product surface to ensure there are no defects that affect product performance; 6) Surface treatment: Dry film lubrication coating with molybdenum disulfide ensures the lubricity of the product, isolates the product surface from the air, and increases the wear and corrosion resistance of the product; 7) Performance test: After passing the performance test, the product design standard requirements are met and the expected effect is achieved, the product manufacturing is completed.

2. A method for processing a titanium alloy high locking bolt as claimed in claim 1, characterized in that; The hexagonal alloy in step 1) is subjected to upsetting and solutionizing at a temperature of 910°C.

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