Method for improving smoothness of inner wall of titanium alloy elbow formed by diameter-expanding push-bending method

Abstract

The invention relates to the technical field of titanium alloy elbow machining, and discloses a method for improving the smoothness of the inner wall of a titanium alloy elbow formed through an expanding push-bending method, the method comprises the following specific steps: S1, process parameter optimization, S2, die optimization design and S3, post-treatment process strengthening, and the S1 process parameter optimization further comprises the steps of S101, push-bending speed regulation and control and S102, expanding amount precise setting; the step S2 of optimal design of the die further comprises the step S201 of reduction of the surface roughness of the die and the step S202 of improvement of a die lubricating system; according to the method, the degree of finish of the inner wall is remarkably improved, the roughness of the inner wall of the titanium alloy elbow is greatly reduced through precise technological parameter optimization, mold optimization design and the strengthening aftertreatment process, and after titanium alloy elbows of common specifications are treated through a new process, the strength of the inner wall of the titanium alloy elbow is improved, and the strength of the inner wall of the titanium alloy elbow is improved. And the roughness of the inner wall can stably reach Ra0.4-Ra1.2 mu m and is improved by more than one order of magnitude compared with that of a traditional process.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy elbow processing, and specifically to a method for improving the inner wall finish of titanium alloy elbows formed by the expanding and pushing bending method. Background Technique

[0002] In high-end fields such as aerospace and chemical engineering, titanium alloy elbows are widely used due to their excellent corrosion resistance and high strength-to-weight ratio. However, in the traditional expanding and pushing bending method for forming titanium alloy elbows, it is difficult to meet the increasingly stringent industrial standards for the inner wall finish. In the original process, parameters such as the pushing bending speed and the expanding amount mostly rely on empirical settings and lack accurate data support, resulting in uneven metal flow and easily generating defects such as inner wall scratches, wrinkles, and tears, and the inner wall roughness is usually between Ra5.0 - Ra6.5μm. In terms of the mold, the surface roughness is relatively high and the lubrication effect is not good, further exacerbating the damage to the inner wall of the pipe. At the same time, the post-treatment process is simple or missing, and it is unable to effectively repair the surface defects generated during the pushing bending process, greatly limiting the application of titanium alloy elbows in key parts such as high-precision fluid transportation systems. Therefore, it is urgent to improve and optimize the expanding and pushing bending method to enhance the inner wall finish of titanium alloy elbows. Summary of the Invention

[0003] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides a method for improving the inner wall finish of titanium alloy elbows formed by the expanding and pushing bending method, which has the advantages of significantly improving the inner wall finish, etc., and solves the problems in the original process that parameters such as the pushing bending speed and the expanding amount mostly rely on empirical settings and lack accurate data support, resulting in uneven metal flow and easily generating defects such as inner wall scratches, wrinkles, and tears.

[0004] (II) Technical Solutions To achieve the above object of the original process that parameters such as the pushing bending speed and the expanding amount mostly rely on empirical settings and lack accurate data support, resulting in uneven metal flow and easily generating defects such as inner wall scratches, wrinkles, and tears, the present invention provides the following technical solutions: A method for improving the inner wall finish of titanium alloy elbows formed by the expanding and pushing bending method, including the following specific method steps: S1 process parameter optimization, S2 mold optimization design, and S3 post-treatment process strengthening. The S1 process parameter optimization further includes S101 pushing bending speed control and S102 accurate setting of the expanding amount; The S2 mold optimization design further includes S201 reduction of the mold surface roughness and S202 improvement of the mold lubrication system; The S3 post-treatment process strengthening further includes S301 vibratory finishing treatment and S302 electrolytic polishing treatment.

[0005] Preferably, for the S101 bending speed regulation: Through preliminary test data, it is found that when the bending speed is in the range of 20 - 30 mm / s, the metal flow on the inner wall of the elbow is relatively stable and it is not easy to generate surface scratches caused by turbulent flow. Within this speed range, bending tests are carried out on titanium alloy elbows with different pipe diameters. When the elbow with a pipe diameter of 50 mm is bent at 25 mm / s, the inner wall roughness is reduced from Ra6.3μm of the original process to Ra4.0μm.

[0006] Preferably, for the S102 precise setting of the expansion amount: According to the material properties and elbow specifications, the expansion amount is accurately calculated. For a titanium alloy elbow with a wall thickness of 3 mm and a pipe diameter of 80 mm, when the expansion amount is controlled within 8% - 10%, that is, 6.4 - 8 mm, it can effectively reduce the inner wall tearing and wrinkles caused by excessive expansion, improve the inner wall finish, reduce the roughness by 30%, and reach Ra3.5μm, showing a significant improvement compared to the unoptimized expansion amount before (Ra5.0μm).

[0007] Preferably, for the S101 bending speed regulation: When the elbow with a pipe diameter of 50 mm is bent at 25 mm / s, the inner wall roughness is reduced from Ra6.3μm of the original process to Ra4.0μm.

[0008] Preferably, for the S201 reduction of the mold surface roughness: The inner wall of the mold is processed by high-precision grinding and polishing processes to make its surface roughness reach Ra0.2 - Ra0.4μm. Through actual production verification, when using the optimized mold, the fine scratches on the inner wall of the titanium alloy elbow caused by the surface friction of the mold during the forming process are significantly reduced, and the inner wall finish of the elbow is improved. For an elbow with a pipe diameter of 100 mm, the inner wall roughness is reduced from the original Ra5.5μm to Ra3.8μm.

[0009] Preferably, for the S202 improvement of the mold lubrication system: A new lubrication channel is designed to ensure that the lubricant is evenly and fully distributed between the mold and the inner wall of the pipe during the bending process. Taking the high-temperature lubricant containing molybdenum disulfide as an example, after optimizing the lubrication system, the effective coverage rate of the lubricant is increased from 70% before to more than 90%, reducing the friction coefficient between the pipe and the mold, further improving the inner wall finish of the elbow. In the production of elbows with a pipe diameter of 60 mm, the inner wall roughness can be stabilized below Ra3.2μm, which is a 40% reduction compared to when the lubrication system was not optimized (original Ra5.3μm).

[0010] Preferably, the S301 vibration finishing treatment: the formed titanium alloy elbow is placed in a vibration finishing machine, specific abrasives (such as ceramic abrasives) and polishing liquid are added, and the elbow is treated at a vibration frequency of 1500-2000 times / minute for 30-45 minutes. After this treatment, the inner wall roughness of the elbow with a diameter of 40mm can be reduced from Ra4.0μm after bending to Ra0.8-Ra1.2μm, effectively removing tiny burrs and surface defects generated during the bending process, and significantly improving the smoothness of the inner wall.

[0011] Preferably, the S302 electrolytic polishing treatment: the inner wall of the elbow is polished by electrolysis, and the inner wall of the elbow is selectively dissolved in a suitable electrolyte at a current density of 20-30A / dm² and a temperature of 40-50°C for 10-15 minutes, so as to smooth the microscopic concave and convex surfaces. For a titanium alloy elbow with a diameter of 70mm, the inner wall roughness can reach Ra0.4-Ra0.6μm after electrolytic polishing, which greatly improves the inner wall finish and meets the requirements of high-precision applications. Compared with vibration finishing, the inner wall roughness is reduced by 50%.

[0012] (III) Beneficial effects Compared with the prior art, the present invention provides a method for improving the inner wall finish of a titanium alloy elbow formed by a diameter expansion push bending method, which has the following beneficial effects: 1. The method for improving the inner wall finish of titanium alloy elbows formed by the expansion and push-bending method significantly improves the inner wall finish: through precise process parameter optimization, mold optimization design and enhanced post-processing technology, the inner wall roughness of the titanium alloy elbow is greatly reduced. For titanium alloy elbows of common specifications, after being treated with the new process, the inner wall roughness can stably reach Ra0.4 - Ra1.2μm, which is more than an order of magnitude higher than the traditional process. It meets the application scenarios with extremely high requirements for inner wall finish, such as aviation engine fuel pipelines, high-end chemical precision fluid delivery systems, etc., effectively reduces the flow resistance and particle adhesion of the fluid medium in the elbow, and improves the overall performance and reliability of the system.

[0013] 2. The method for improving the inner wall finish of titanium alloy elbows formed by the expansion and push-bending method, which improves production efficiency and product qualification rate: based on data-driven process parameter optimization, the number of trial and error times is reduced and the production cycle is shortened. At the same time, mold optimization and stable process make product quality more stable, and the product qualification rate is increased from the original 70% to more than 90%, which reduces production costs and enhances the company's competitiveness in the market. It is especially suitable for manufacturing companies that engage in large-scale industrial production of titanium alloy elbows, bringing them significant economic benefits and market advantages.

[0014] 3. The method for improving the inner wall finish of titanium alloy elbows by the improved expanding and pushing bending method. This method expands the application fields: The optimized forming method enables titanium alloy elbows to meet the requirements of more high-end fields, such as ultra-pure gas transmission pipelines in semiconductor chip manufacturing, high-precision fluid channels in medical devices, etc. It broadens the market application scope of titanium alloy elbows, promotes the technological progress and development of related industries, provides technical support for the application of titanium alloy materials under more complex and precise working conditions, and promotes the development process of the entire high-end equipment manufacturing industry. Detailed implementation manners

[0015] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0016] This solution provides a technical solution, specifically, a method for improving the inner wall finish of titanium alloy elbows by the expanding and pushing bending method, including the following specific method steps: S1 process parameter optimization, S2 die optimization design, and S3 post-treatment process strengthening; The S1 process parameter optimization further includes S101 pushing bending speed regulation and S102 accurate setting of the expanding amount; The S2 die optimization design further includes S201 reduction of the die surface roughness and S202 improvement of the die lubrication system; The S3 post-treatment process strengthening further includes S301 vibratory finishing treatment and S302 electrolytic polishing treatment; S1 process parameter optimization: S101 pushing bending speed regulation: Through the previous test data, it is found that when the pushing bending speed is in the range of 20 - 30 mm / s, the metal flow on the inner wall of the elbow is relatively stable and it is not easy to generate surface scratches caused by turbulent flow. Within this speed range, pushing bending tests are carried out on titanium alloy elbows with different pipe diameters. When the elbow with a pipe diameter of 50 mm is pushed bent at 25 mm / s, the inner wall roughness is reduced from the original Ra6.3 μm of the process to about Ra4.0 μm; S102 accurate setting of the expanding amount: According to the material characteristics and elbow specifications, the expanding amount is accurately calculated. For a titanium alloy elbow with a wall thickness of 3 mm and a pipe diameter of 80 mm, when the expanding amount is controlled within 8% - 10%, that is, 6.4 - 8 mm, it can effectively reduce the inner wall tearing and wrinkles caused by excessive expansion, improve the inner wall finish, reduce the roughness by 30%, and reach about Ra3.5 μm, showing a significant improvement compared with the previous unoptimized expanding amount (Ra5.0 μm); S2 die optimization design: S201 Reduction of mold surface roughness: The inner wall of the mold is processed by high-precision grinding and polishing processes to make its surface roughness reach Ra0.2 - Ra0.4μm. Through actual production verification, when using the optimized mold, the fine scratches on the inner wall of the titanium alloy elbow caused by the surface friction of the mold during the forming process are significantly reduced, and the surface finish of the elbow inner wall is improved. For elbows with a pipe diameter of 100mm, the inner wall roughness is reduced from the original Ra5.5μm to Ra3.8μm; S202 Improvement of the mold lubrication system: Design a new lubrication channel to ensure that the lubricant is evenly and fully distributed between the mold and the inner wall of the pipe during the push-bending process. Taking the high-temperature lubricant containing molybdenum disulfide as an example, after optimizing the lubrication system, the effective coverage rate of the lubricant is increased from 70% before to over 90%, reducing the friction coefficient between the pipe and the mold, and further improving the surface finish of the elbow inner wall. In the production of elbows with a pipe diameter of 60mm, the inner wall roughness can be stabilized below Ra3.2μm, which is 40% lower than that without optimizing the lubrication system (the original Ra5.3μm); S3 Enhancement of post-treatment process: S301 Vibration finishing treatment: Place the formed titanium alloy elbow in a vibration finishing machine, add specific abrasives (such as ceramic abrasives) and polishing liquid, and process it at a vibration frequency of 1500 - 2000 times / minute for 30 - 45 minutes. After this treatment, the inner wall roughness of elbows with a pipe diameter of 40mm can be reduced from Ra4.0μm after push-bending to Ra0.8 - Ra1.2μm, effectively removing the tiny burrs and surface defects generated during the push-bending process, and significantly improving the inner wall surface finish; S302 Electrolytic polishing treatment: Use electrolysis to polish the inner wall of the elbow. In a suitable electrolyte (such as a phosphoric acid - sulfuric acid mixture), process it for 10 - 15 minutes under the conditions of a current density of 20 - 30A / dm² and a temperature of 40 - 50°C, which can cause selective dissolution of the inner wall of the elbow and flatten the microscopic uneven surfaces. For titanium alloy elbows with a pipe diameter of 70mm, the inner wall roughness can reach Ra0.4 - Ra0.6μm after electrolytic polishing, greatly improving the inner wall surface finish and meeting the requirements of high-precision applications. Compared with the inner wall roughness after vibration finishing, it is reduced by 50% again.

[0017] Furthermore, this method significantly improves the inner wall finish: Through precise process parameter optimization, optimized die design, and enhanced post-treatment processes, the inner wall roughness of titanium alloy elbows is greatly reduced. For titanium alloy elbows of common specifications, after being processed by the new process, the inner wall roughness can stably reach Ra0.4 - Ra1.2μm, which is more than an order of magnitude higher than that of the traditional process, meeting the requirements of application scenarios with extremely high inner wall finish requirements, such as aviation engine fuel pipelines and high-end chemical precision fluid transportation systems, effectively reducing the flow resistance and particle adhesion of the fluid medium in the elbow, and improving the overall performance and reliability of the system.

[0018] Furthermore, this method improves production efficiency and product qualification rate: Based on data-driven process parameter optimization, the number of trial-and-error attempts is reduced, and the production cycle is shortened. At the same time, die optimization and a stable process make the product quality more stable. The product qualification rate has increased from about 70% to over 90%, reducing production costs and enhancing the competitiveness of enterprises in the market. It is especially suitable for manufacturing enterprises that mass-produce titanium alloy elbows, bringing significant economic benefits and market advantages to them.

[0019] Furthermore, this method expands the application fields: The optimized forming method enables titanium alloy elbows to meet the requirements of more high-end fields, such as ultra-pure gas transportation pipelines in semiconductor chip manufacturing and high-precision fluid channels in medical devices, broadening the market application scope of titanium alloy elbows, promoting the technological progress and development of related industries, providing technical support for the application of titanium alloy materials in more complex and precise working conditions, and driving the development process of the entire high-end equipment manufacturing industry.

[0020] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for improving the inner wall finish of titanium alloy elbows formed by the expanding-diameter pushing-bending method, including the following specific method steps: S1 process parameter optimization, S2 die optimization design, and S3 post-treatment process strengthening, characterized in that: The optimization of the S1 process parameters also includes the regulation of the pushing and bending speed in S101 and the precise setting of the diameter expansion amount in S102; The optimized design of the S2 die also includes the reduction of the die surface roughness in S201 and the improvement of the die lubrication system in S202; The enhancement of the S3 post-treatment process also includes the vibratory finishing treatment in S301 and the electrolytic polishing treatment in S302.

2. A method for improving the inner wall finish of a titanium alloy elbow formed by the diameter-expanding push-bending method according to claim 1, characterized in that: The regulation of the pushing and bending speed in S101: Through the preliminary test data, it is found that when the pushing and bending speed is in the range of 20 - 30 mm / s, the metal flow on the inner wall of the elbow is relatively stable and it is not easy to generate surface scratches caused by turbulent flow. Within this speed range, the pushing and bending tests are carried out on titanium alloy elbows with different pipe diameters.

3. A method for improving the inner wall finish of a titanium alloy elbow formed by the expanding and pushing bending method according to claim 1, characterized in that: The precise setting of the diameter expansion amount in S102: According to the material properties and elbow specifications, the diameter expansion amount is accurately calculated. For a titanium alloy elbow with a wall thickness of 3 mm and a pipe diameter of 80 mm, when the diameter expansion amount is controlled within 8% - 10%, that is, 6.4 - 8 mm, it can effectively reduce the inner wall tearing and wrinkles caused by excessive diameter expansion, improve the inner wall finish, reduce the roughness by 30% to reach Ra3.5μm, showing significant improvement compared with the unoptimized diameter expansion amount before (Ra5.0μm).

4. A method for improving the inner wall finish of a titanium alloy elbow formed by the expanding and bending method according to claim 1, characterized in that: The regulation of the pushing and bending speed in S101: When the 50-mm diameter elbow is pushed and bent at 25 mm / s, the inner wall roughness is reduced from Ra6.3μm of the original process to Ra4.0μm.

5. A method for improving the inner wall finish of a titanium alloy elbow formed by the expanding-diameter push-bending method according to claim 1, characterized in that: The reduction of the die surface roughness in S201: The inner wall of the die is processed by high-precision grinding and polishing processes to make its surface roughness reach Ra0.2 - Ra0.4μm. Through actual production verification, when using the optimized die, the fine scratches on the inner wall of the titanium alloy elbow caused by the die surface friction during the forming process are significantly reduced, and the inner wall finish of the elbow is improved. For a 100-mm diameter elbow, the inner wall roughness is reduced from the original Ra5.5μm to Ra3.8μm.

6. A method for improving the inner wall finish of a titanium alloy elbow formed by the expanding-diameter push-bending method according to claim 1, characterized in that: The improvement of the die lubrication system in S202: A new lubrication channel is designed to ensure that the lubricant is evenly and fully distributed between the die and the inner wall of the pipe during the pushing and bending process. Taking the high-temperature lubricant containing molybdenum disulfide as an example, after optimizing the lubrication system, the effective coverage rate of the lubricant is increased from 70% before to more than 90%, reducing the friction coefficient between the pipe and the die, further improving the inner wall finish of the elbow. During the production of a 60-mm diameter elbow, the inner wall roughness can be stabilized below Ra3.2μm, which is a 40% reduction compared with the unoptimized lubrication system (original Ra5.3μm).

7. A method for improving the inner wall finish of a titanium alloy elbow formed by the expanding-diameter push-bending method according to claim 1, characterized in that: The vibratory finishing treatment in S301: The formed titanium alloy elbow is placed in a vibratory finishing machine, and specific abrasives (such as ceramic abrasives) and polishing fluids are added, and it is treated at a vibration frequency of 1500 - 2000 times / minute for 30 - 45 minutes. After this treatment, the inner wall roughness of a 40-mm diameter elbow can be reduced from Ra4.0μm after pushing and bending to Ra0.8 - Ra1.2μm, effectively removing the tiny burrs and surface defects generated during the pushing and bending process, and significantly improving the inner wall finish.

8. A method for improving the inner wall finish of a titanium alloy elbow formed by the expanding-diameter push-bending method according to claim 1, characterized in that: The S302 electrolytic polishing treatment: The inner wall of the elbow is polished by electrolysis. In a suitable electrolyte, it is treated for 10 - 15 minutes under the conditions of a current density of 20 - 30 A / dm² and a temperature of 40 - 50 °C, which can cause selective dissolution of the inner wall of the elbow, flatten the microscopic uneven surfaces. For a titanium alloy elbow with a pipe diameter of 70 mm, the inner wall roughness can reach Ra0.4 - Ra0.6 μm after electrolytic polishing, greatly improving the inner wall finish and meeting the requirements of high-precision applications. Compared with the inner wall roughness after vibratory finishing, it is reduced by 50%.