Preparation method of high-strength stainless steel precision spring and application thereof

Abstract

The application provides a preparation method of a high-strength stainless steel precision spring and application thereof, and comprises the following steps: step 1, a spring is wound by using an automatic spring winding machine on 0Cr17Ni7Al raw material; step 2, the wound spring is cleaned and then vacuum stress relief heat treatment is carried out; step 3, the two ends of the spring are ground flat, the grinding amount is not less than 4 / 5 of the circumference of the spring, burrs on the inner and outer diameters and the end of the spring are removed, and the size of the spring is corrected; step 4, the spring is cleaned and then vacuum aging treatment is carried out; step 5, the spring is subjected to 10-15 times of full compression of circle collision at room temperature, and then is subjected to warm aging treatment; step 6, the spring is subjected to shot blasting treatment and surface finishing; and step 7, the spring is subjected to inspection, and a qualified 0Cr17Ni7Al stainless steel spring is obtained. The method has the advantages of low cost, short cycle, high qualified rate and the like, and the prepared stainless steel spring has the characteristics of high elasticity, high precision, high stability and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of aviation manufacturing and application, and particularly relates to a preparation method of a high-strength stainless steel precision spring and application thereof. BACKGROUND

[0002] The fuel nozzle is a key component of an aero-engine, which atomizes and vaporizes fuel to ensure stable combustion with high efficiency. With the development of engine performance, the requirements for the fuel flow control boundary and control precision of the fuel nozzle are continuously improved. The fuel nozzle of an advanced aero-engine usually controls the effective opening at different pressures through a special-shaped hole precisely machined on a valve plug and a precision spring matched with the valve plug, so as to achieve the purpose of adjusting the fuel flow. The strength and precision of the spring have an important influence on ensuring the working reliability of the fuel nozzle.

[0003] 0Cr17Ni7Al is a semi-austenitic precipitation hardening stainless steel, which has the characteristics of high strength, high hardness, fatigue resistance and corrosion resistance. The tensile strength of the 0Cr17Ni7Al stainless steel cold-drawn wire after aging treatment can reach 2000 MPa, which is an ideal material for manufacturing the fuel nozzle spring of an aero-engine.

[0004] The manufacturing process of the 0Cr17Ni7Al stainless steel spring is complex, and needs to go through multiple important processes such as winding, stress relief heat treatment, aging treatment and surface treatment. If the process arrangement is unreasonable, the process parameters are not properly selected, or the analysis and inspection are not in place, it will have a great influence on the product quality, and cannot meet the use requirements. SUMMARY

[0005] Therefore, the application provides a preparation method of a high-strength stainless steel precision spring and application thereof. The preparation process of the method is controllable, has the advantages of low cost, short cycle, high pass rate and the like, and the stainless steel spring prepared has the characteristics of high elasticity, high precision and high stability.

[0006] The application provides the following technical scheme: a preparation method of a high-strength stainless steel precision spring, comprising the following steps:

[0007] Step 1: using an automatic spring winding machine to wind the spring from the 0Cr17Ni7Al raw material, the winding direction is right, and 1 / 4 of the length of the two ends of the spring is gradually tightened during the winding process;

[0008] Step 2: after the wound spring is cleaned, the spring is subjected to vacuum stress relief heat treatment, the loading temperature of the spring during the vacuum stress relief heat treatment is not higher than 120 DEG C, and the pressure in the furnace is kept below 0.10 Pa;

[0009] Step 3, grinding the both ends of the spring, the grinding amount is not less than 4 / 5 of the circumference of the spring, then removing burrs of the inner and outer diameters and the end of the spring, and correcting the size of the spring;

[0010] Step 4, after cleaning the spring, vacuum aging treatment is performed, the actual temperature of the spring during the vacuum aging treatment is not higher than 120℃, and the pressure in the furnace is kept below 0.10Pa;

[0011] Step 5, after the vacuum aging treatment, the spring is subjected to 10-15 times of full compression of circle collision at room temperature, and then is subjected to heating and loading aging treatment;

[0012] Step 6, the spring is subjected to shot blasting treatment and surface finishing, the shot blasting medium is S110 cast steel shot with a diameter of 0.3mm, and the shot blasting strength is 0.15A-0.20A;

[0013] Step 7, the spring is subjected to inspection, and the qualified 0Cr17Ni7Al stainless steel spring is obtained.

[0014] According to an embodiment of the present application, before the step 1, the 0Cr17Ni7Al raw material is first subjected to re-inspection, and the re-inspection standard is that the 0Cr17Ni7Al raw material is wire material, is cold-drawn into shape after being annealed at 1050℃ for 60min, the cold-drawing deformation is not less than 60%, the grain size of the wire material is finer than 8, and the surface is free of defects.

[0015] According to an embodiment of the present application, in the step 1, after winding, the elastic performance of the spring is detected, the diameter of the mandrel, the working turns and the height of the spring are regulated according to the detection result of the elastic performance, and every 50 springs are wound, 3 springs are randomly selected to detect whether the inner diameter, the outer diameter, the height and the perpendicularity are qualified, if not, the unqualified spring product is removed, and the winding parameters are adjusted.

[0016] According to an embodiment of the present application, in the step 2, during the vacuum stress relief heat treatment, the actual temperature of the spring is 450℃-470℃, and after being kept at the temperature for 1-2h, argon is filled in the furnace for cooling.

[0017] According to an embodiment of the present application, in the step 4, during the vacuum aging treatment, the actual temperature of the spring is 482℃±5℃, and after being kept at the temperature for 4-6h, argon is filled in the furnace for cooling.

[0018] According to an embodiment of the present application, in the step 5, before the heating and loading aging treatment, the spring is first clamped on a tool, so that the spring reaches the full compression state of circle collision, and then the spring and the tool are put into a vacuum furnace for heating, the heating temperature is 100℃-250℃, and the time of the heating and loading aging treatment is 4h-6h.

[0019] According to one embodiment of the present application, the shot peening coverage is higher than 90% in the step 6.

[0020] The application further provides application of the high-strength stainless steel precision spring prepared by the method in an aero-engine.

[0021] Compared with the prior art, the at least one technical scheme adopted by the embodiments of the present application can achieve the beneficial effects at least including:

[0022] 1. The 0Cr17Ni7Al stainless steel spring prepared by the application has the characteristics of high elasticity, high precision and high stability, and the size of the spring is stable and the elastic performance does not change obviously after multiple uses.

[0023] 2. The 0Cr17Ni7Al stainless steel spring prepared by the application has the advantages of low cost and short cycle, and the product qualified rate can reach more than 80%.

[0024] 3. The spring prepared by the application and qualified after inspection can meet the use requirements of the fuel injection group of the aero-engine, and problems such as excessive elastic fluctuation or premature fatigue fracture do not occur during service. DETAILED DESCRIPTION

[0025] The embodiments of the present application are described in detail below.

[0026] The embodiments of the present application are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure. Obviously, the described embodiments are only some of the embodiments of the present application, not all. The present application can also be implemented or applied by other different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0027] The embodiments of the present application provide a preparation method of a high-strength stainless steel precision spring, which controls process parameters such as spring winding, stress relief heat treatment, aging treatment, warm and loaded aging treatment, and shot peening treatment, and carries out corresponding detection to prepare a high-precision high-strength stainless steel spring. The specific steps include:

[0028] Step 1, complete the 0Cr17Ni7Al stainless steel spring raw material reinspection, the raw material is wire, after 1050℃ / 60min annealing, cold drawing forming, the cold drawing deformation is not less than 60%. The grain size of the wire should be finer than 8 level, the surface is smooth, no cracks, folding, burr, rust and other defects.

[0029] Step 2, use the automatic spring winding machine to wind the spring, the rotation direction is right, and the 1 / 4 circumference of the two ends of the spring is gradually tightened. According to the elastic performance test results, adjust the mandrel diameter, working turns and spring height, when the elastic performance test results are low, the mandrel diameter or working turns can be appropriately reduced or the spring height can be increased within the tolerance range, until the elastic index requirements are met. After winding 50 springs, randomly select 3 springs for inner diameter, outer diameter, height and perpendicularity detection, and the detection results should all be qualified. If there are unqualified items, the size of each spring should be detected one by one, and unqualified products should be removed. If the qualified rate of 50 springs is less than 80%, the raw material or winding process should be adjusted.

[0030] Step 3, after the wound spring is cleaned, vacuum stress relief heat treatment is carried out, the spring loading temperature during vacuum stress relief heat treatment should not be higher than 120℃, the pressure in the furnace is extracted to below 0.10Pa before heating and the pressure is maintained below this value during the stress relief heat treatment. During stress relief heat treatment, the actual temperature of the spring should be between 450℃ and 470℃, and the temperature should be maintained for 1-2h, then the furnace is filled with argon gas for cooling, the pressure of the filled argon gas should make the cooling rate of the spring close to the air cooling rate.

[0031] Step 4, grind the two ends of the spring, the grinding amount should not be less than 4 / 5 of the circumference, remove the burrs on the inner and outer diameters and the end, and correct the size of the spring.

[0032] Step 5, after the spring is cleaned, vacuum aging treatment is carried out, the spring loading temperature during vacuum aging treatment should not be higher than 120℃, the pressure in the furnace is extracted to below 0.10Pa before heating and the pressure is maintained below this value during the aging treatment. During aging treatment, the actual temperature of the spring should be between 482℃±5℃, and the temperature should be maintained for 4-6h, then the furnace is filled with argon gas for cooling, the pressure of the filled argon gas should make the cooling rate of the spring close to the air cooling rate; wherein, the vacuum aging treatment should select a type II heat treatment furnace with a furnace temperature uniformity≯±5℃.

[0033] Step 6, after the aging treatment, the spring is subjected to 10-15 times of full compression of circle collision circle at room temperature. Then, the spring is loaded on the tool to reach the full compression state of circle collision circle before warm and load aging treatment. The spring and tool are placed in the vacuum furnace for heating, the heating temperature is the maximum temperature used by the spring in the aero-engine, usually between 100℃ and 250℃; the time of warm and load aging treatment is 4h-6h.

[0034] Step 7, shot blasting and surface finishing of the spring, shot blasting medium is Φ0.3mm S110 cast steel shot, shot blasting intensity is 0.15A-0.20A, shot blasting coverage should reach more than 90%. After shot blasting, vibration finishing treatment is carried out, so that the surface roughness is not more than Ra0.8μm.

[0035] Step 8, inspection of the spring, the spring should be clean and bright, without visible scratches, burrs, scratches, folds, cavities and other defects, and no cracks and other defects are detected by fluorescence detection. The inner and outer diameters of each spring are detected by using a checking rod and a checking cylinder, and there is no interference phenomenon between the checking rod and cylinder and the spring. A certain number of springs are randomly selected, the natural height, inner diameter and outer diameter of the spring are detected by using a vernier caliper, and the perpendicularity of the spring is detected by using a ruler and a protractor. The spring force of the prepared spring is detected by using a spring tension testing machine, and the spring force is detected again after 100 times full compression, and the qualified 0Cr17Ni7Al stainless steel spring is obtained.

[0036] After the above detection results are all qualified, the 0Cr17Ni7Al stainless steel spring can be applied to an aero-engine, and the main application parts are fuel nozzles and the like.

[0037] In a specific embodiment, the spring raw material used is Φ3.5mm 0Cr17Ni7Al stainless steel cold drawn wire material, and the cold drawing deformation is 64%. After inspection, the grain size of the raw material wire material is 10 levels, the diameter deviation is -0.02-+0.01mm, and the room temperature tensile strength of the cold drawn wire material and the cold drawn+aged wire material (aging treatment process is 482℃±5℃, holding for 60min, air cooling) is 1553MPa and 1865MPa respectively. The surface of the wire material is smooth and clean, without cracks, folds, burrs, rust and other defects, and is coiled into a disc shape.

[0038] The winding of the GH4169 alloy spring is carried out by using an automatic spring winding machine, and the rotation direction is right. The control parameters are: working turns are 6 turns, total turns are 7.5±0.2 turns, pitch is 4.4±0.1mm, natural height is 35.4±0.3mm, outer diameter is Φ16.0±0.2mm, and the 1 / 4 circumference of the two ends of the spring is gradually tightened. After winding 50 springs, 3 springs are randomly selected for inspection of the number of turns, pitch, outer diameter, natural height and perpendicularity, and the detection results are all qualified, which are listed in Table 1.

[0039] Table 1: Size detection results of the 0Cr17Ni7Al stainless steel spring prepared after winding

[0040]

[0041] The wound spring is cleaned and then vacuum stress relief heat treated. The spring is loaded into the furnace at a temperature of 40°C, heated to a temperature of 470°C, and held for 1 hour. The pressure in the furnace is not higher than 0.1 Pa. Then, the furnace is filled with 0.2 MPa argon gas to cool the spring. The spring is then ground on an automatic spring grinder to a grinding amount of not less than 4 / 5 of the length, to ensure uniform grinding. The inner and outer diameters and the ends of the spring are deburred and the dimensions of the spring are corrected. The spring is cleaned and then vacuum aged. The actual temperature of the spring during aging is between 482°C±5°C, and the spring is held at this temperature for 4.5 hours. Then, the furnace is filled with argon gas to cool the spring. The aged spring is then fully compressed 15 times at room temperature. Then, the spring is clamped on a tool so that it is fully compressed. The spring and the tool are placed in a furnace and heated to a temperature of 220°C. The spring is then aged for 5 hours under heating and loading. The spring is then shot blasted using Φ0.3 mm S110 cast steel shot at a strength of 0.15A-0.20A, so that the shot blasting coverage of the outer diameter and the cross section of the spring is more than 100%. The shot blasted spring is then surface vibration polished.

[0042] The machined spring has a clean and bright surface, a surface roughness of less than Ra0.8 μm, and no visible scratches, burrs, scratches, folds, holes, or other defects. The spring has no cracks or other defects detected by fluorescence. The inner and outer diameters of each spring are detected using a checking rod and a checking cylinder, and there is no interference between the checking rod and cylinder and the spring. Eight springs are randomly selected, and the natural height, inner diameter, and outer diameter of the springs are detected using a vernier caliper. The perpendicularity of the springs is detected using a ruler and a protractor. The results are shown in Table 2. Eight springs are randomly selected, and the natural height of the prepared springs is detected using a vernier caliper. The spring force of the springs is detected using a spring tension tester. The results are shown in Table 3. The spring force and height of the eight springs are detected again after the springs are fully compressed 100 times. The results are shown in Table 3. The natural height and spring force of the springs do not change significantly after the springs are fully compressed 100 times, and are equivalent to those of the prepared springs.

[0043] Table 2: Size detection results of 0Cr17Ni7Al stainless steel finished springs

[0044]

[0045] Table 3: Spring force and spring force detection results of 0Cr17Ni7Al stainless steel finished springs after 100 times full compression

[0046]

[0047] The preparation method of the stainless steel compression spring of the present application adopts 0Cr17Ni7Al cold-drawing material as raw material, and the preparation process is as follows: raw material inspection, winding, cleaning, stress relief heat treatment, end face grinding, aging treatment, full compression, clamping, warm aging treatment, shot blasting treatment, polishing treatment, cleaning, inspection, oil sealing and packaging. The stainless steel spring prepared by the method has the characteristics of high elasticity, high dimensional accuracy and high stability, and the long-term use temperature can reach 250 DEG C. The qualified spring can be reliably applied in the fuel nozzle valve of an aero-engine.

[0048] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of manufacturing a high-strength stainless steel precision spring, characterized by, The method comprises the following steps: Step 1, using an automatic spring winding machine to wind the 0Cr17Ni7Al raw material into a spring, the winding direction is right, and the 1 / 4 circumference of the two ends of the spring is gradually tightened during the winding process; In step 1, the elastic properties of the spring are detected after winding, and the core shaft diameter, the number of working turns and the spring height are adjusted according to the elastic property detection result; and every 50 springs are wound, 3 springs are randomly selected to detect whether the inner diameter, outer diameter, height and perpendicularity are qualified, if not, the unqualified spring products are removed and the winding parameters are adjusted; Step 2, the wound spring is cleaned and then vacuum stress relief heat treated, the loading temperature of the spring during the vacuum stress relief heat treatment is not higher than 120℃, and the pressure in the furnace is kept below 0.10Pa; Step 3, the two ends of the spring are ground flat, the grinding amount is not less than 4 / 5 of the circumference of the spring, then the inner and outer diameters of the spring and the burrs at the ends are removed, and the size of the spring is corrected; Step 4, the spring is cleaned and then vacuum aging treated, the loading temperature of the spring during the vacuum aging treatment is not higher than 120℃, and the pressure in the furnace is kept below 0.10Pa; Step 5, the spring after the vacuum aging treatment is subjected to 10-15 times of full compression of circle collision at room temperature, and then subjected to warm and loaded aging treatment; Step 6, the spring is subjected to shot blasting treatment and surface finishing, the shot blasting medium is S110 cast steel shot with a diameter of 0.3mm, and the shot blasting intensity is 0.15A-0.20A; Step 7, the spring is inspected to obtain qualified 0Cr17Ni7Al stainless steel spring.

2. The method of claim 1, wherein, Before step 1, the 0Cr17Ni7Al raw material is first reexamined, and the reexamination standard is that the 0Cr17Ni7Al raw material is wire material, which is cold-drawn into shape after being annealed at 1050℃ for 60min, the cold-drawing deformation is not less than 60%, the grain size of the wire material should be finer than 8 levels, and the surface is free of defects.

3. The method of claim 1, wherein, In step 2, during the vacuum stress relief heat treatment, the actual temperature of the spring is 450℃-470℃, and after being kept at this temperature for 1-2h, argon is filled in the furnace for cooling.

4. The method of claim 1, wherein, In step 4, during the vacuum aging treatment, the actual temperature of the spring is 482℃±5℃, and after being kept at this temperature for 4-6h, argon is filled in the furnace for cooling.

5. The method of claim 1, wherein, In step 5, before the warm and loaded aging treatment, the spring is first clamped on a tooling so that the spring reaches the full compression state of circle collision, then the spring and the tooling are put into a vacuum furnace for heating, the heating temperature is 100℃-250℃, and the time of the warm and loaded aging treatment is 4h-6h.

6. The method of claim 1, wherein, In step 6, the shot blasting coverage during the shot blasting treatment is higher than 90%.

7. The use of a high-strength stainless steel precision spring produced by the method according to any one of claims 1 to 6 in an aeroengine, characterized in that, The high-strength stainless steel precision spring is applied to the fuel nozzle of an aero-engine.

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