Method for processing long-life high-elasticity beryllium bronze thin-wall ring

Abstract

The application provides a long-life high-elasticity beryllium bronze thin-wall ring processing method, characterized by adopting a C17200 beryllium bronze round bar in a solid solution state for processing, and comprising the following steps: S1, rough processing: rough machining of a blank, and processing the beryllium bronze round bar into a beryllium bronze pipe; S2, solid solution treatment: after the beryllium bronze pipe is bound, it is vertically put into a furnace, kept at 780±20 DEG C for 10-50 min, vertically cooled in water, and the transfer time is less than or equal to 8 s; S3, drawing treatment: the beryllium bronze pipe is drawn; S4, cryogenic treatment: the part is placed in a liquid nitrogen tank, kept at low temperature for a certain time, and then taken out to restore to room temperature; S5, finishing; S6, aging treatment; S7, plasma nanometer polishing; and S8, stabilization. The beryllium bronze thin-wall ring processing method disclosed by the application can meet the requirement of keeping a good service state during long-term pressure rolling of the thin-wall ring, and can meet the requirement of fatigue rotating rolling of hundreds of millions of cycles in an extreme environment.

Description

Technical Field

[0001] This invention relates to the field of machining, and in particular to a method for machining long-life, high-elasticity beryllium bronze thin-walled rings. Background Technology

[0002] Space-grade conductive rings are precision electrical transmission components used in spacecraft to achieve power and signal transmission between two relatively rotating bodies. They are widely used in the solar-orientation drive mechanisms of various spacecraft solar cell wings, as well as in the drive devices of payloads such as mechanical scanning microwave radiometers and microwave imagers. Currently, various spacecraft are generally required to achieve a service life of more than 5 years in low Earth orbit and more than 10 years in medium and high Earth orbit, which places technical demands on space-grade conductive rings for high rotational speed, long lifespan (hundreds of millions of revolutions), and high reliability.

[0003] To meet the requirements of long service life and high revolutions per minute, a conductive rolling ring structure is one implementation approach. Its core principle is to replace sliding friction with rolling friction, thereby significantly reducing frictional torque and consequently reducing wear and debris accumulation. This offers advantages such as long service life, low loss, high transmission efficiency, low electrical noise, and high speed stability. High-elasticity beryllium bronze is used as the key thin-walled ring component—the flexible ring—in the rolling ring current-carrying friction pair. The compressibility of the flexible ring determines the frictional torque of the loop structure and the elastic fatigue life of the loop structure at a certain speed. The compressibility of the flexible ring has a significant impact on the dynamic resistance change. Simultaneously, the thin-walled flexible ring component is manufactured through turning, requiring precise shape and dimensional accuracy while controlling the material microstructure to achieve good fatigue strength, high conductivity, and low elastic hysteresis.

[0004] Currently, foreign conductive ring products boast advanced technology, a wide range of product specifications, and performance indicators covering the application requirements of low, medium, and high-speed orbits. They have 18-year on-orbit application cases and can basically meet various usage requirements such as long lifespan and high speed, possessing rich development experience and on-orbit test data. Domestic conductive rings can guarantee 5 years of on-orbit lifespan for low-speed orbits and 15 years for high-speed orbits, but there is still a significant gap in meeting the requirement of hundreds of millions of revolutions per minute. The main gap lies in the key technologies of microstructure control and precision manufacturing of the flexible thin-walled beryllium bronze material for the rolling electric transmission friction pair. Therefore, there is an urgent need to break through the design, development, and application of long-life rolling ring friction pairs to achieve the domestic substitution of high-speed, hundreds-of-millions-of-revolutions rolling ring conductive rings.

[0005] Patent document CN114871705 (application number: 202210627446.1) discloses a method for preparing a self-stabilizing high-precision conductive thin-walled ring and its processing fixture. This invention discloses a method for preparing a self-stabilizing high-precision conductive thin-walled ring and its processing fixture, which features a radial arc angle on both ends of the conductive thin-walled ring for conductive contact, and a holding contact on the outer circumference of the ring to separate the conductive area from the holding and fixing area. In the preparation of the conductive thin-walled ring, C17200 beryllium bronze material in an aged state of TF00 is first used to achieve the conductive... The forming of conductive thin-walled rings involves placing the ring on a ZrO2 ceramic mandrel for solution treatment and aging to completely remove residual processing stress and maintain the dimensional stability and accuracy of the ring. In the forming process, a self-centering radial locking fixture composed of an expanding mandrel, an expanding shaft, and a positioning sleeve is used. This solves the problems of deformation during clamping and the inability to guarantee dimensional and positional tolerances after multiple clampings. Furthermore, it offers high clamping efficiency, is suitable for batch processing, and can be widely applied to clamping devices for conductive thin-walled rings with strict requirements for perpendicularity and coaxiality. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for machining long-life, high-elasticity beryllium bronze thin-walled rings, characterized by using a C17200 beryllium bronze round bar in a solid solution state for machining, comprising the following steps: S1. Rough machining: Roughly cut the billet and process the beryllium bronze round bar into beryllium bronze tube. Leave a machining allowance of 2mm on each side. S2. Solution treatment: After the beryllium bronze tubes are tied, they are vertically placed into the furnace at 780±20℃ for 10 to 50 minutes, then vertically placed into water for cooling, with a transfer time of ≤8 seconds. S3. Drawing process: The beryllium bronze tube is drawn. S4. Cryogenic treatment: Place the parts in a liquid nitrogen tank and keep them at a low temperature for a certain period of time. Then remove the parts and allow them to return to room temperature. S5. Finishing: Using a soft jaw tooling, the inner hole is first machined to the required size, and the outer circle contour is machined to the required size using a PCD tool. Then, the width is machined to the required size using a cutting tool in a blanking manner to obtain a high-elasticity beryllium bronze thin-walled ring. S6. Aging Treatment: The high-elasticity beryllium bronze thin-walled ring is placed freely in a clean material box. A vacuum furnace with protective atmosphere is used. After the furnace is evacuated, nitrogen is refilled. The part is heated with the furnace. The graded aging process is to first hold at 180-200℃ for 1-2℃, then raise the temperature to 290-330℃ and hold for 1-3 hours. After air cooling, the hardness and strength are tested. The hardness is HV370-410. The maximum grain size of the material after aging is ≤60μm. S7. Plasma Nanopolishing: Plasma nanopolishing equipment is used to polish the outer surface of the thin-walled ring, removing machining marks and improving the surface finish of the thin-walled ring. S8. Stabilization: Place the parts in the furnace at room temperature, heat them up at a rate of ≤10℃ / min, hold them at 100±20℃ for 3-4 hours, air cool them, then place them at -60 to -70℃ for 2-3 hours, and allow them to return to room temperature in the air. Repeat this cycle 1-2 times.

[0007] The beryllium bronze thin-walled ring processing method disclosed in this invention can ensure that the thin-walled ring maintains a good service condition during long-term pressure rolling and can meet hundreds of millions of fatigue rotation rolling cycles under extreme environments.

[0008] The beneficial effects of the long-life, high-elasticity beryllium bronze thin-walled ring processing method provided by this invention are: 1) This invention is the first to use a combination of machining, drawing and heat treatment for high elastic beryllium bronze (C17200). By adding a drawing process between solution treatment and graded aging, cold deformation is introduced into the raw material, which improves the alloy’s conductivity, mechanical strength and wear resistance, thereby ensuring that the high elastic thin-walled ring can maintain dimensional accuracy and stability during long-term service. 2) This invention employs a cryogenic treatment method to relieve stress and optimize the microstructure of high-elasticity beryllium bronze material, reduce grain boundary reactions, refine grains, and further improve the fatigue life of the material; 3) After the final product size is processed, the present invention uses laser polishing to remove machining marks, improve the surface finish of the thin-walled ring, and prevent micro-tool marks from becoming micro-crack sources during the long-term rolling service of the thin-walled ring, leading to fracture failure. Attached Figure Description

[0009] The invention will be further described below with reference to the accompanying drawings: Figure 1 A schematic diagram of a long-life, highly elastic beryllium bronze thin-walled ring.

[0010] Figure 2 This is a schematic diagram of a thin-walled ring being sampled from a pipe. Detailed Implementation

[0011] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for processing long-life, highly elastic beryllium bronze thin-walled rings according to the present invention. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0012] This invention discloses a method for machining long-life, high-elasticity beryllium bronze thin-walled rings. The machining process is as follows: rough machining, solution treatment, drawing, cryogenic treatment, finish machining, aging, plasma nanopolishing, and stabilization. Solution treatment of the rough-machined beryllium bronze raw material homogenizes the microstructure and improves performance consistency. Drawing treatment of the rod-shaped beryllium bronze raw material further refines the grains, improving the wear resistance and fatigue life of the beryllium bronze material. Prolonged cryogenic treatment and stabilization further enhance the grain boundary reaction of the beryllium bronze material and remove machining stress, thereby ensuring the precision and stability of the high-elasticity thin-walled ring. During the machining process of the long-life, high-elasticity beryllium bronze thin-walled ring, a diamond tool is used for precision machining of the thin-walled ring, and plasma nanopolishing further eliminates surface machining marks to prevent fracture failure during long-term service.

[0013] In the long-life, high-elasticity beryllium bronze thin-walled ring processing method of the present invention, the thin-walled ring is mainly used in the conductive rolling ring system of the aerospace long-life scanning drive mechanism. The high-elasticity beryllium bronze thin-walled ring uses C17200 beryllium bronze round bars in solid solution state as processing raw materials. It is required that the C17200 beryllium bronze raw materials should be free of harmful β phases with a size ≥5μm, and long strip continuous β phases are not allowed.

[0014] The method for processing long-life, high-elasticity beryllium bronze thin-walled rings of the present invention includes the following steps: S1. Rough machining: Roughly cut the billet and process the round bar into a tube, leaving a machining allowance of 2mm on each side; S2. Solution treatment: After the beryllium bronze tubes are tied, they are vertically placed into the furnace and held at 780±20℃ for 10 to 50 minutes. Then they are vertically placed into water for cooling, with a transfer time of ≤8 seconds.

[0015] S3. Drawing process: The beryllium bronze tube is drawn.

[0016] In one embodiment, the drawing process is as follows: the outer die of the drawing die has a half-cone angle of 12°, the inner die core is coated with a WC coating to increase the core strength, the surface roughness should be ≤0.2μm, multiple drawing is performed with a single-pass deformation amount of 6% to 8%, and drawing is stopped when the single-sided allowance is 1mm. By introducing cold drawing deformation, the uniformity of the beryllium bronze material structure is improved, and the performance consistency is improved.

[0017] S4. Cryogenic treatment: Place the parts in a liquid nitrogen tank and keep them at a low temperature for a certain period of time. Then remove the parts and allow them to return to room temperature. In one embodiment, during the cryogenic treatment process, the temperature is -190±20℃ and the holding time is 120~168h. Cryogenic treatment can effectively suppress the grain boundary reaction of beryllium bronze, improve the conductivity of beryllium bronze, and extend its fatigue life.

[0018] S5. Finishing: Using a soft jaw tool, the inner hole is machined to the required size in one clamping operation. Then, a diamond tool is used to machine the outer diameter to the required size. Finally, a cutting tool is used to machine the width to the required size in a blanking process, resulting in a high-elasticity beryllium bronze thin-walled ring.

[0019] In one implementation, during the finishing process, a soft-jaw chuck is used for one-time clamping. The inner hole diameter D1 is machined to the required position, with the machining length slightly greater than the part width by 0.5mm. The outer contour is machined using a diamond tool, and the outer circle D2 and the fillet diameter D3 are formed simultaneously. The surface finish is better than Ra0.5. The thin-walled ring width is machined using a cutting tool and then blanked.

[0020] S6. Aging Treatment: The high-elasticity beryllium bronze thin-walled ring is freely placed in a clean material box and placed in a vacuum furnace under protective atmosphere. After the furnace is evacuated, it is refilled with nitrogen. The part is heated with the furnace. The grading aging process is as follows: first, it is held at 180-200℃ for 1-2℃, then heated to 290-330℃ and held for 1-3 hours, followed by air cooling. After aging, the hardness and strength are tested. The hardness is required to be HV370-410, and the maximum grain size of the material after aging is ≤60μm.

[0021] S7. Plasma Nanopolishing: Plasma nanopolishing equipment is used to polish the outer surface of the thin-walled ring, removing machining marks and improving the surface finish of the thin-walled ring.

[0022] In one implementation, a plasma nanopolishing device is used to polish the thin-walled ring for 30 seconds, which improves the surface finish of the flexible ring by more than 0.4.

[0023] S8. Stabilization: Place the parts in the furnace at room temperature, heat them up at a rate of ≤10℃ / min, hold them at 100±20℃ for 3-4 hours, air cool them, then place them at -60 to -70℃ for 2-3 hours, and allow them to return to room temperature in the air. Repeat this cycle 1-2 times.

[0024] In one implementation, during the stabilization process, the sized flexible ring needs to be vacuum-packed in a vacuum bag and placed in a low-temperature chamber. During the positive temperature process, a vacuum furnace needs to be used to prevent the sized beryllium bronze material from oxidizing and discoloring. Example

[0025] Reference Figures 1-2 As shown, the present invention discloses a method for processing long-life, high-elasticity beryllium bronze thin-walled rings, the specific steps of which are as follows: S1. Rough machining: The billet is roughed to process the f25mm solid solution state C17200 beryllium bronze round bar into a tube with f24.5mm*f20mm and a wall thickness of 2.25mm. S2. Solution treatment: After binding the beryllium bronze tube with uncoated iron wire, hang it on an iron hook. After the ammonia furnace temperature reaches 770℃, hang the tube vertically into the furnace and place it in the effective temperature zone of the furnace. After holding it at the temperature for 30 minutes, loosen the iron hook and let the tube fall freely into the water for cooling. The cooling time is ≥3 minutes.

[0026] S3. Drawing process: The outer die half-cone angle of the drawing die is 12°, the inner die core is made of WC material, and the surface roughness should be ≤0.2μm. Three drawing operations are performed with a single-pass deformation amount of 6%. The drawing is stopped when the tube size reaches f18mm*f15.5mm. The tube wall thickness is 1.25mm at this time.

[0027] S4. Cryogenic treatment: After binding the pipe with uncoated iron wire, hang it in a liquid nitrogen tank and keep it at -180℃ for 120 hours. Then, take out the pipe and restore it to room temperature. S5. Finishing: See attached. Figure 2 As shown, the part material base is clamped using a soft jaw chuck. First, the inner circle dimension D1 is machined to the required depth of 1.5mm, slightly larger than the width L of the thin-walled ring. Then, the outer circle diameter D2 and the fillet diameter D3 are machined to the required depth using a diamond tool, ensuring one-time forming. The feed rate is 0.015mm / r. Finally, the width dimension L is machined using a cutting tool and the part is unloaded. The part is then placed on a mandrel fixture and deburred and flanged using metallographic sandpaper.

[0028] S6. Aging Treatment: The high-elasticity beryllium bronze thin-walled ring and the sample are laid flat in a clean iron box, with a furnace gap of ≥5mm. A pre-evacuated atmosphere protective vacuum furnace is used. After the furnace chamber is evacuated, nitrogen is refilled. The parts are placed in the furnace at room temperature. The furnace temperature is raised to 200℃ and held for 1℃, then raised to 295℃ and held for 3 hours, followed by air cooling. After aging, one thin-walled ring is randomly selected and inlaid for microhardness testing. The sample taken with the furnace is subjected to strength testing and microstructure analysis.

[0029] S7. Plasma nanopolishing: Place the part into the plasma nanopolishing equipment, set the polishing time to 30 seconds, and then check the surface finish and the outer diameter D2.

[0030] S8. Stabilization: The thin-walled ring is placed in an iron box and placed in an atmosphere-protected furnace at room temperature. The furnace is heated at a rate of 8℃ / min and held at 100℃ for 3 hours. After air cooling, the thin-walled ring is placed in a plastic box, sealed in a vacuum bag to prevent oxidation and discoloration, and placed in a -60℃ low-temperature chamber for 2 hours. After reaching room temperature, it is removed and allowed to return to room temperature in the air. The thin-walled ring is then placed in an iron box and placed in an atmosphere-protected furnace at room temperature. The furnace is heated at a rate of 8℃ / min and held at 100℃ for 3 hours. After air cooling.

[0031] The contents not described in detail in this specification are prior art known to those skilled in the art. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for processing long-life, high-elasticity beryllium bronze thin-walled rings, characterized in that, It is processed using C17200 beryllium bronze round bars in a solid solution state, including the following steps: S1. Rough machining: Roughly cut the billet and process the beryllium bronze round bar into beryllium bronze tube. Leave a machining allowance of 2mm on each side. S2. Solution treatment: After the beryllium bronze tubes are tied, they are vertically placed into the furnace at 780±20℃ for 10 to 50 minutes, then vertically placed into water for cooling, with a transfer time of ≤8 seconds. S3. Drawing process: The beryllium bronze tube is drawn. S4. Cryogenic treatment: Place the parts in a liquid nitrogen tank and keep them at a low temperature for a certain period of time. Then remove the parts and allow them to return to room temperature. S5. Finishing: Using a soft jaw tooling, the inner hole is first machined to the required size, and the outer circle contour is machined to the required size using a PCD tool. Then, the width is machined to the required size using a cutting tool in a blanking manner to obtain a high-elasticity beryllium bronze thin-walled ring. S6. Aging Treatment: The high-elasticity beryllium bronze thin-walled ring is placed freely in a clean material box. A vacuum furnace with protective atmosphere is used. After the furnace is evacuated, nitrogen is refilled. The part is heated with the furnace. The graded aging process is to first hold at 180-200℃ for 1-2℃, then raise the temperature to 290-330℃ and hold for 1-3 hours. After air cooling, the hardness and strength are tested. The hardness is HV370-410. The maximum grain size of the material after aging is ≤60μm. S7. Plasma Nanopolishing: Plasma nanopolishing equipment is used to polish the outer surface of the thin-walled ring, removing machining marks and improving the surface finish of the thin-walled ring. S8. Stabilization: Place the parts in the furnace at room temperature, heat them up at a rate of ≤10℃ / min, hold them at 100±20℃ for 3-4 hours, air cool them, then place them at -60 to -70℃ for 2-3 hours, and allow them to return to room temperature in the air. Repeat this cycle 1-2 times.

2. The method for processing a long-life, high-elasticity beryllium bronze thin-walled ring according to claim 1, characterized in that, The C17200 beryllium bronze rod has no β phase with a size ≥5μm and no elongated continuous β phase.

3. The method for processing a long-life, high-elasticity beryllium bronze thin-walled ring according to claim 1, characterized in that, The drawing process in step S3 is as follows: the outer die half-cone angle of the drawing die is selected as 12°, the inner die core is made of WC material, the surface roughness should be ≤0.2μm, and multiple drawing is performed with a single-pass deformation amount of 6% to 8%. Drawing is stopped when the single-side allowance is 1mm.

4. The method for processing a long-life, high-elasticity beryllium bronze thin-walled ring according to claim 1, characterized in that, During the cryogenic treatment in step S4, the temperature is -190±20℃ and the holding time is 120~168h.

5. The method for processing a long-life, high-elasticity beryllium bronze thin-walled ring according to claim 1, characterized in that, In the finishing process of step S5, a soft jaw chuck is used for one-time clamping. First, the inner hole diameter D1 is machined to the required position, and the machining length is slightly greater than the width of the part by 0.5mm. The outer contour is machined using a PCD tool, and the outer circle D2 and the fillet diameter D3 are formed simultaneously. The surface finish is better than Ra0.

5. The width of the thin-walled ring is machined using a cutting tool and then blanked.

6. The method for processing a long-life, high-elasticity beryllium bronze thin-walled ring according to claim 1, characterized in that, In step S7, the thin-walled ring is polished for 30 seconds using a plasma nanopolishing device, which improves the surface finish of the flexible ring by more than 0.

4.

7. The method for processing a long-life, high-elasticity beryllium bronze thin-walled ring according to claim 1, characterized in that, In step S8, during the stabilization process, the flexible ring with the correct dimensions is vacuum-packed in a vacuum bag and then placed in a low-temperature chamber. During the positive temperature process, a vacuum furnace must be used to prevent the beryllium bronze material with the correct dimensions from oxidizing and discoloring.

Images