An ultrasonic roll forming method for a non-flared catheter sleeve

Abstract

An ultrasonic roll processing method of a non-flared conduit sleeve includes the following processes: blanking, heat treatment, machining, ultrasonic roll processing, inner hole processing, sand blasting, passivation and dry film spraying. In the ultrasonic roll processing process, the spherical surface of the workpiece is processed by ultrasonic roll processing equipment, the ultrasonic frequency is controlled to be 30 KHz, the amplitude is controlled to be 6-10 mu m, the roll processing linear velocity is controlled to be 13.5-16.5 m / min, and the static pressure is controlled to be 585-615 N. Through the optimization design of the processing process of the sleeve and the control of the process parameters, the roughness and surface hardness of the spherical surface of the sleeve are improved, the sealing performance of the connecting part of the sleeve and the pipe joint is improved, and the use requirement of the high pressure of the pipeline connecting piece of the new aircraft model is met.

Description

Technical Field

[0001] This invention relates to a method for processing hydraulic pipeline components, and more particularly to an ultrasonic rolling processing method suitable for non-flared conduit sleeves in aircraft hydraulic control systems. Background Technology

[0002] With the rapid development of aviation equipment technology, the pressure requirements for hydraulic systems are gradually increasing. However, the flared pipe connection currently in use has many drawbacks, such as frequent cracks and fractures, which cause potential hazards of "running," "leaking," "dripping," and "leaking," becoming a technical bottleneck restricting the reliability of aircraft.

[0003] Developed countries around the world began adopting non-flared joints to gradually replace flared joints starting in the 1950s, as shown in the attached diagram. Figure 1 , Figure 2 As shown, non-flared piping components mainly include a combined conduit (including an outer nut 1, a sleeve 2, and a pipe body 3), pipe fittings (including plugs), and nut components (including caps). A line seal is formed through the contact between the inner conical surface 4-1 of the pipe fitting 4 and the spherical curved surface 2-1 of the sleeve 2 in the combined conduit. The outer nut 1 provides the axial tightening force required for the line seal. Non-flared piping components have advantages such as good fatigue resistance and easy control of early failures. Currently, non-flared piping components have evolved to the third generation, namely, the roll-formed non-flared piping component. However, due to limitations in existing processing technology, the roughness and surface hardness of the spherical curved surface 2-1 of the sleeve 2 in the non-flared piping component are difficult to further improve. This results in the sealing performance of the non-flared piping component failing to meet the 35MPa pressure test standard requirements of the new aircraft model. Therefore, it is urgent to upgrade and improve the existing sleeve processing technology to improve the sealing performance of the connection between the sleeve and the pipe fitting, and meet the high-pressure requirements of the piping connections of the new aircraft model. Summary of the Invention

[0004] This invention provides an ultrasonic rolling process for non-flared conduit sleeves, aiming to improve the surface roughness and surface hardness of the spherical curved surface of the sleeve by optimizing the design of the sleeve processing process and controlling the process parameters, thereby improving the sealing performance of the connection between the sleeve and the pipe fitting and meeting the high-pressure requirements of the pipeline connection parts of new aircraft models.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An ultrasonic rolling process for a non-flared conduit sleeve includes material preparation, heat treatment, machining, ultrasonic rolling, internal hole machining, sandblasting, passivation, and dry film spraying. The specific operation steps are as follows: a. Blanking: Stainless steel bars are selected as raw materials. The diameter of the bars is 3-5mm larger than the outer diameter of the sleeve product. The bars are cut to a set length and their outer surfaces are rough-machined using a lathe. b. Heat treatment: Solution heat treatment and aging treatment are performed on the workpiece; c. Machining: The workpiece is machined on a lathe to form a spherical curved surface at the contact section between the sleeve and the pipe fitting; d. Ultrasonic rolling: The spherical surface of the workpiece is ultrasonically rolled using an ultrasonic rolling equipment. During the ultrasonic rolling process, the ultrasonic frequency is controlled at 30KHz, the amplitude is 6~10μm, the rolling processing speed is 13.5~16.5m / min, and the static pressure is 585~615N. e. Internal hole machining: Machining the internal hole of the workpiece using a CNC machine tool; f. Sandblasting: Sandblasting is performed on the surface of the workpiece, except for spherical curved surfaces. g. Passivation: Passivation treatment is performed on the surface of the workpiece, except for spherical curved surfaces, using a passivation solution with a set ratio. h. Dry film spraying: Dry film spraying is performed on the surface of the workpiece, except for spherical curved surfaces, through a process of degreasing, spraying, and drying.

[0006] In the ultrasonic rolling process for the above-mentioned non-flared conduit sleeve, the stainless steel bar material selected in step a is 05Cr15Ni5Cu4Nb.

[0007] In the ultrasonic rolling process for the above-mentioned non-flared conduit sleeve, in step b, the workpiece is first subjected to solution heat treatment, with the solution temperature controlled at 1030-1060 ºC, held for 30-35 minutes and then air-cooled. Then, the workpiece is subjected to aging treatment, with the aging temperature controlled at 475-485 ºC, held for 55-60 minutes and then air-cooled.

[0008] In the ultrasonic rolling process for the above-mentioned non-flared conduit sleeve, the surface roughness Ra of the spherical curved surface formed after turning in step c is ≤1.250μm.

[0009] In the above-mentioned ultrasonic rolling process for non-flared conduit sleeves, in step d, the ultrasonic rolling equipment includes an ultrasonic power supply, a built-in energy converter, a cemented carbide indenter, and a lubrication system. The cemented carbide indenter is installed at the power output end of the built-in energy converter. The ultrasonic power supply drives the built-in energy converter to provide dynamic impact energy to the cemented carbide indenter. The ultrasonic rolling equipment is fixed on the tool post of a CNC lathe and moves laterally and longitudinally with the tool post to perform ultrasonic rolling on the spherical surface of the workpiece that is rotated by the CNC machine tool. After ultrasonic rolling, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be ≤0.051μm and the surface Vickers hardness value is ≥514kg / mm. 2 .

[0010] In the ultrasonic rolling process for the above-mentioned non-flared conduit sleeve, step e includes two operations: drilling and boring.

[0011] In the ultrasonic rolling process for the above-mentioned non-flared conduit sleeve, the passivation solution in step g is a nitric acid solution.

[0012] In the above-mentioned ultrasonic rolling process for non-flared conduit sleeves, in steps f, g, and h, the ultrasonic rolling area of ​​the workpiece is shielded and protected by protective fixtures.

[0013] This invention provides an ultrasonic rolling process for non-flared conduit sleeves. It applies ultrasonic rolling (USRP) technology to the processing of 35MPa pressure-rolled non-flared conduit sleeves for aircraft. During the rolling process, the combination of static and dynamic impact loads causes intense plastic deformation of the metal surface. Simultaneously, the plastic flow generated during rolling fills the troughs of the material surface, reducing surface roughness, increasing surface hardness, and introducing beneficial residual compressive stress into the surface layer. This positively impacts the material's fatigue strength, wear resistance, and corrosion resistance. Therefore, this invention improves the sealing performance of the connection between the sleeve and the fitting, meeting the high-pressure requirements of new aircraft piping connections. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the non-flared pipe fitting involved in this invention; Figure 2 This is a schematic diagram of the exploded structure of the pipe fitting and pipe sleeve in a non-flared pipe assembly; Figure 3 This is a hardness distribution diagram of the surface hardening layer of a non-flared conduit sleeve, obtained through a preferred embodiment of the present invention and conventional processes.

[0015] Explanation of each label in the diagram: 1 is the outer nut; 2 is the sleeve, 2-1 is the spherical surface; 3 is the pipe body; 4 is the pipe fitting, 4-1 is the inner conical surface. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] Referring to Figure 3, this invention provides an ultrasonic rolling process for non-flared conduit sleeves, mainly including blanking, heat treatment, machining, ultrasonic rolling, internal hole machining, sandblasting, passivation, and dry film spraying. The ultrasonic rolling (USRP) process combines static loads with dynamic impact loads to induce severe plastic deformation on the metal surface, thereby achieving surface strengthening and improved smoothness. Ideal USRP parameters can balance dislocation-dominated grain refinement with grain boundary migration-dominated grain phasing; however, excessively low or high ultrasonic energy will affect surface quality. Based on the above principles, this invention optimizes the sleeve processing procedure and effectively controls the process parameters. Preferred embodiments are listed below: Example 1

[0018] a. Material cutting: Select stainless steel bars of grade 05Cr15Ni5Cu4Nb as raw materials. The diameter of the bars is 3-5mm larger than the outer diameter of the sleeve product. Cut to the set length and rough machine the outer surface of the bars using a lathe. b. Heat treatment: First, the workpiece is subjected to solution heat treatment, with the solution temperature controlled at 1030 ºC, held for 30 minutes and then air-cooled. Then, the workpiece is subjected to aging treatment, with the aging temperature controlled at 485 ºC, held for 60 minutes and then air-cooled. c. Machining: The workpiece is machined on a lathe to form a spherical curved surface at the contact section between the sleeve and the pipe joint. The surface roughness of the spherical curved surface after machining is Ra=1.198μm. d. Ultrasonic Rolling: The spherical surface of a workpiece is ultrasonically rolled using an ultrasonic rolling device. This device includes an ultrasonic power supply, a built-in energy converter, a carbide indenter, and a lubrication system. The carbide indenter is installed at the power output end of the built-in energy converter. The ultrasonic power supply drives the built-in energy converter to provide dynamic impact energy to the carbide indenter. The ultrasonic rolling device is fixed on the tool post of a CNC lathe and moves laterally and longitudinally with the tool post to perform ultrasonic rolling on the spherical surface of the workpiece, which is rotated by the CNC machine tool. During the ultrasonic rolling process, the ultrasonic frequency is controlled at 30 kHz, the amplitude at 8 μm, the rolling speed at 15 m / min, and the static pressure at 600 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured using a testing instrument, resulting in a surface Vickers hardness value of 504 kg / mm². 2 ; e. Internal hole machining: Machining the internal hole of the workpiece using a CNC machine tool, including two operations: drilling and boring. f. Sandblasting: The ultrasonic rolling processing area of ​​the workpiece is shielded and protected by protective fixtures, and sandblasting is performed on the surface of the workpiece except for the spherical curved surface. g. Passivation: The ultrasonic rolling processing area of ​​the workpiece is shielded and protected by protective fixtures. A nitric acid solution with a set ratio is used as the passivation liquid to passivate the surface of the workpiece except for the spherical curved surface. h. Dry film spraying: The ultrasonic rolling processing area of ​​the workpiece is shielded and protected by protective fixtures. The dry film spraying operation is completed on the surface of the workpiece except for the spherical curved surface through degreasing, spraying and drying processes in sequence. Example 2

[0019] The difference between this embodiment and Embodiment 1 lies in steps b, c, and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. c. Machining: The workpiece is machined on a lathe to form a spherical curved surface at the contact section between the sleeve and the pipe joint. The surface roughness of the spherical curved surface after machining is Ra=1.201μm. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 8 μm, the rolling speed at 15 m / min, and the static pressure at 585 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.037 μm, and the surface Vickers hardness value is 513 kg / mm². 2 . Example 3

[0020] The difference between this embodiment and Embodiment 1 lies in steps b, c, and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. c. Machining: The workpiece is machined on a lathe to form a spherical curved surface at the contact section between the sleeve and the pipe joint. The surface roughness of the spherical curved surface after machining is Ra=1.205μm. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 8 μm, the rolling speed at 15 m / min, and the static pressure at 615 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.041 μm, and the surface Vickers hardness value is 527 kg / mm². 2 . Example 4

[0021] The difference between this embodiment and Embodiment 1 lies in steps b, c, and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. c. Machining: The workpiece is machined on a lathe to form a spherical curved surface at the contact section between the sleeve and the pipe joint. The surface roughness of the spherical curved surface after machining is Ra=1.202μm. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 8 μm, the rolling speed at 15 m / min, and the static pressure at 600 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.029 μm, and the surface Vickers hardness value is 525 kg / mm². 2 . Example 5

[0022] The difference between this embodiment and Embodiment 1 lies in steps b and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 6 μm, the rolling speed at 16.5 m / min, and the static pressure at 600 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.051 μm, and the surface Vickers hardness value is 514 kg / mm². 2 . Example 6

[0023] The difference between this embodiment and Embodiment 1 lies in steps b and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 10 μm, the rolling speed at 13.5 m / min, and the static pressure at 600 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.045 μm, and the surface Vickers hardness value is 528 kg / mm². 2 . Example 7

[0024] The difference between this embodiment and Embodiment 1 lies in steps b and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 6 μm, the rolling speed at 13.5 m / min, and the static pressure at 600 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.044 μm, and the surface Vickers hardness value is 515 kg / mm². 2 . Example 8

[0025] The difference between this embodiment and Embodiment 1 lies in steps b and d, specifically: b. Heat treatment: control the solution temperature at 1055 ºC, hold for 30 minutes and then air cool. Then perform aging treatment on the workpiece, control the aging temperature at 480 ºC, hold for 60 minutes and then air cool. d. Ultrasonic rolling: The ultrasonic frequency is controlled at 30 kHz, the amplitude at 10 μm, the rolling speed at 16.5 m / min, and the static pressure at 600 N. After the ultrasonic rolling operation is completed, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be 0.042 μm, and the surface Vickers hardness value is 517 kg / mm². 2 .

[0026] See Figure 3 For ease of comparison, hardness distribution diagrams were drawn for the surface hardening layer of the non-flared conduit sleeves produced by Embodiments 1 to 4 of the present invention and by conventional processes. Lines III, IV, V, and VI correspond to the hardness distribution within the surface hardening layer of the non-flared conduit sleeves produced by Embodiments 1 to 4, respectively. (Due to significant overlap between the lines of Embodiments 5 to 8 and Embodiments 1 to 4, they are not shown in the diagrams for clarity.) Figure 3 The figures show the hardness distribution within the surface hardened layer of the unflared conduit sleeve completed through Examples 5 to 8; Line I corresponds to the hardness distribution within the surface hardened layer of the unflared conduit sleeve completed without a rolling process; Line II corresponds to the hardness distribution within the surface hardened layer of the unflared conduit sleeve completed by the conventional rolling method. As can be seen from the six sets of figures, after using the method of the present invention, the surface hardness of the workpiece can be increased from 424 kg / mm². 2 (The maximum surface hardness of the unflared conduit sleeve completed without a rolling process is 424 kg / mm) 2 The maximum surface hardness of the non-flared conduit sleeve produced by the traditional rolling method is 455 kg / mm². 2 Increased to 527 kg / mm 2This improves the sealing performance of the connection between the sleeve and the fitting, meeting the high-pressure requirements of aircraft piping connections.

Claims

1. An ultrasonic rolling process for a non-flared conduit sleeve, characterized in that: It includes the processes of blanking, heat treatment, machining, ultrasonic rolling, internal hole machining, sandblasting, passivation, and dry film spraying. The specific operation steps are as follows: a. Blanking: Stainless steel bars are selected as raw materials. The diameter of the bars is 3-5mm larger than the outer diameter of the sleeve product. The bars are cut to a set length and their outer surfaces are rough-machined using a lathe. b. Heat treatment: Solution heat treatment and aging treatment are performed on the workpiece; c. Machining: The workpiece is machined on a lathe to form a spherical curved surface at the contact section between the sleeve and the pipe fitting; d. Ultrasonic rolling: The spherical surface of the workpiece is ultrasonically rolled using an ultrasonic rolling equipment. During the ultrasonic rolling process, the ultrasonic frequency is controlled at 30KHz, the amplitude is 6~10μm, the rolling processing speed is 13.5~16.5m / min, and the static pressure is 585~615N. e. Internal hole machining: Machining the internal hole of the workpiece using a CNC machine tool; f. Sandblasting: Sandblasting is performed on the surface of the workpiece, except for spherical curved surfaces. g. Passivation: Passivation treatment is performed on the surface of the workpiece, except for spherical curved surfaces, using a passivation solution with a set ratio. h. Dry film spraying: Dry film spraying is performed on the surface of the workpiece, except for spherical curved surfaces, through a process of degreasing, spraying, and drying.

2. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 1, characterized in that: In step a, the stainless steel bar material selected is grade 05Cr15Ni5Cu4Nb.

3. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 2, characterized in that: In step b, the workpiece is first subjected to solution heat treatment, with the solution temperature controlled at 1030–1060 ºC, held for 30–35 minutes and then air-cooled. Then, the workpiece is subjected to aging treatment, with the aging temperature controlled at 475–485 ºC, held for 55–60 minutes and then air-cooled.

4. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 2 or 3, characterized in that: In step c, the surface roughness Ra of the spherical curved surface formed after turning is ≤1.250μm.

5. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 4, characterized in that: In step d, the ultrasonic rolling equipment includes an ultrasonic power supply, a built-in energy converter, a cemented carbide indenter, and a lubrication system. The cemented carbide indenter is installed at the power output end of the built-in energy converter. The ultrasonic power supply drives the built-in energy converter to provide dynamic impact energy to the cemented carbide indenter. The ultrasonic rolling equipment is fixed on the tool post of a CNC lathe and moves laterally and longitudinally with the tool post to perform ultrasonic rolling on the spherical surface of the workpiece that is rotated by the CNC machine tool. After ultrasonic rolling, the surface roughness Ra of the spherical surface of the workpiece is measured by a testing instrument to be ≤0.051μm and the surface Vickers hardness value is ≥514kg / mm. 2 .

6. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 5, characterized in that: In step e, the machining of the workpiece's inner hole includes two operations: drilling and boring.

7. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 5, characterized in that: In step g, the passivation solution is a nitric acid solution.

8. The ultrasonic rolling processing method for non-flared conduit sleeves according to claim 7, characterized in that: In steps f, g, and h, the ultrasonic rolling processing area of ​​the workpiece is shielded and protected by protective fixtures.

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