A processing technology for improving the manufacturing qualification rate of lubricating oil guide pipe

Abstract

This invention discloses a processing technology to improve the manufacturing yield of lubricating oil conduits, relating to the field of aero-engine component processing technology. Addressing the problem of low yield rates caused by deformation at the bending points leading to out-of-tolerance φ5 precision dimensions at both ends when processing 1Cr18Ni9Ti lubricating oil conduits using traditional stamping processes, this process includes blanking, chrome plating, CNC bending, grinding, and quality inspection steps: the blanking dimension is extended to 170mm to accommodate CNC bending machine clamping; chrome plating is applied to the entire conduit, covering only the grinding areas at both ends, avoiding the bending points; precise bending is achieved using a CNC bending machine to control deformation; overall grinding ensures precision dimensions; and multi-node inspection controls quality. This invention abandons the traditional stamping process, effectively controlling bending deformation and chrome plating defects through process optimization, significantly improving the quality of parts processing. It is suitable for processing thin-walled, small-diameter bent parts with precision dimensions, meeting the production requirements of aero-engines.

Description

Technical Field

[0001] This invention relates to the field of aero-engine component processing technology, specifically a processing technology to improve the manufacturing qualification rate of lubricating oil conduits. Background Technology

[0002] The lubricating oil conduit, a critical pipeline component in aero-engines, is a single-piece pipeline part with a diameter of 5mm, a wall thickness of 1mm, and a material grade of 1Cr18Ni9Ti. It is formed by bending and has an unfolded length of approximately 173mm. The core machining requirement for this part is to ensure precise dimensions at both ends. However, traditional machining processes using a one-piece stamping die present several problems. There is a gap in the clamping of the part, and the part is not accurately positioned during the processing, resulting in increased deformation. There is a large gap between the part and the stamping die, and the part becomes loose during the processing, which further aggravates the deformation. The stamping process itself has a large deformation, and there are almost no straight sections in the transition area between the straight section and the curved arc of the part. The bending deformation has a significant impact on the precision dimensions. In the traditional processing route, the blank size is 80mm, and a segmented chrome plating process is used, which makes it difficult to guarantee the dimensional accuracy in subsequent processing. Therefore, we propose a processing technology to improve the manufacturing yield of lubricating oil conduits. Summary of the Invention

[0003] The purpose of this invention is to provide a processing technology that improves the manufacturing yield of lubricating oil conduits, thus solving the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a processing technology to improve the manufacturing qualification rate of lubricating oil conduits, step one, blanking process: for lubricating oil conduits with material grade 1Cr18Ni9Ti, diameter 5mm, wall thickness 1mm, and unfolded length of about 173mm, the blanking size is set to 170mm. The blanking size is extended by 90mm compared to the traditional 80mm blanking size. The extended part is used to adapt to the clamping requirements of CNC pipe bending machine to ensure stable clamping of parts during processing; Step 2, Chromium Plating Process: A full-body chromium plating process is adopted instead of the traditional segmented chromium plating process. Through CNC pipe bending data calculation and actual verification, the chromium plating area is precisely limited, requiring only the two ends of the part to meet the φ5 requirement. Chromium plating is applied to the grinding area that requires precision dimensions, avoiding the parts that will be bent later, to prevent the chromium plating layer from developing wrinkles, cracks or peeling during the bending process. Step 3, CNC bending process: Abandoning the traditional stamping process, a CNC pipe bending machine is used for bending. Based on the bending angle, bending radius and material properties of the lubricating pipe, the clamping force, bending speed and bending angle compensation value of the CNC pipe bending machine are preset to accurately bend the chrome-plated parts and control the amount of deformation of the parts during the bending process. Step 4: Grinding Process: After CNC bending is completed, the chrome-plated areas at both ends of the part are ground as a whole. During the grinding process, step-by-step measurement and precision calibration are used to ensure that the φ5 at both ends of the part is properly ground. The precision dimensions conform to the drawing requirements; Step 5, Quality Inspection Process: Before and after CNC bending, inspect the outer diameter of the part near the bending area. The inspection points should include at least the maximum and minimum size inspection points along the circumference to ensure that the dimensional change after bending does not exceed 0.008mm and that all inspected dimensions are within the tolerance range, so that the part processing qualification rate is not less than 90%.

[0005] In a preferred embodiment of the present invention, during the blanking process, the blanking cut must be flat and free of defects such as burrs, cracks and oxide scale. The perpendicularity deviation of the cut should not exceed 0.02mm to avoid subsequent processing dimensional deviations due to blanking quality issues.

[0006] In a preferred embodiment of the present invention, the chromium plating process has a uniform chromium plating layer thickness with a thickness deviation controlled within ±0.005mm. The hardness of the chromium plating layer is HRC35-45, and the adhesion meets the requirement of no peeling in the cross-cut adhesion test, thus avoiding the impact of poor plating performance on processing accuracy or the service life of parts.

[0007] As a preferred embodiment of the present invention, the CNC pipe bending machine needs to be calibrated before bending. The calibration includes the positioning accuracy of the clamping mechanism, the rotation accuracy of the bending spindle, and the accuracy of the angle measurement system, so as to ensure that the part is accurately positioned and the bending deformation is uniform and controllable during the processing.

[0008] In a preferred embodiment of the present invention, in the CNC bending process, the bending speed of the CNC pipe bending machine is set to 5-10 mm / s, the clamping force is set to 0.3-0.5 MPa, and the bending angle compensation value is adjusted according to the actual bending test results, with a range of 0.5°-1.5°.

[0009] In a preferred embodiment of the present invention, the grinding process is carried out using a precision cylindrical grinding machine with a grinding wheel grit size of 800-1000 mesh, a grinding speed of 30-40 m / s, and a feed rate of 0.001-0.003 mm / r, ensuring that the surface roughness Ra of the part after grinding is Ra≤0.8 μm.

[0010] In a preferred embodiment of the present invention, in the quality inspection process, a micrometer with an accuracy of not less than 0.001 mm is used to measure the size of the inspection points. Each inspection point is measured at least 3 times, and the average value is taken as the final inspection result to ensure the accuracy of the inspection data.

[0011] In a preferred embodiment of the present invention, the CNC pipe bending machine is a fully automatic CNC pipe bending machine with multi-axis linkage control function, positioning accuracy ≤ ±0.01mm, angle control accuracy ≤ ±0.1°, which can accurately realize the bending and forming of lubricating oil conduits.

[0012] In a preferred embodiment of the present invention, after the grinding process is completed, the parts need to be deburred by ultrasonic cleaning to remove iron filings and impurities generated during grinding. The cleaning time is 10-15 minutes to ensure that the surface of the parts is clean and free of residue.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention replaces the traditional stamping process with CNC tube bending technology. CNC tube bending machines have high processing precision and can accurately control the amount of bending deformation. Tests have verified that the outer diameter of the part near the bending area changes little before and after bending, and all are within the allowable tolerance range. By increasing the blanking size to 170mm, the clamping requirements of the CNC pipe bending machine were solved, the positioning stability of the parts during processing was improved, and the deformation caused by loose clamping was reduced. The chemical chromium plating process, by adjusting the chromium plating range and adopting an overall chromium plating method, not only ensures the chromium plating quality in precision dimensional areas, but also avoids defects in the chromium plating layer during bending. At the same time, the overall grinding process further improves dimensional accuracy. This process eliminates the need for rework or remanufacturing of traditional stamping dies, reducing production costs. Furthermore, the process is mature and reliable, significantly improving the part manufacturing qualification rate. Attached Figure Description

[0014] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a process flow diagram of a method for improving the manufacturing qualification rate of lubricating oil conduits according to the present invention. Detailed Implementation

[0015] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0016] like Figure 1 As shown, a processing technology to improve the manufacturing pass rate of lubricating oil conduits is implemented as follows: Parts preparation: The lubricating oil conduit to be processed must meet the following core parameters: the material grade is 1Cr18Ni9Ti, which has excellent corrosion resistance, high temperature strength and processing stability, and is a commonly used preferred material for aero-engine parts; the part has a diameter of 5mm and a wall thickness of 1mm, belonging to a thin-walled small-diameter structure, with an unfolded length of approximately 173mm, and both ends must strictly guarantee the φ5mm precision dimension requirement, the surface roughness must reach the high precision standard of Ra≤0.8μm, and the dimensional change of key parts after bending must be controlled within 0.008mm to ensure that the assembly accuracy and sealing performance requirements of the aero-engine piping system are met; Seamless steel pipes made of 1Cr18Ni9Ti material conforming to GB / T1220-2007 standard are purchased. Before the raw materials arrive on site, they must undergo strict inspection: eddy current testing is used to detect no cracks, inclusions or other defects on the surface; a spectral analyzer is used to verify that the chemical composition meets the standards; and a hardness tester is used to test the hardness of the raw materials to ensure that they meet the processing performance requirements.

[0017] Equipment and tool preparation Material cutting equipment: A high-precision CNC shearing machine is selected, with a shearing accuracy error of ≤±0.01mm, which can accurately achieve the material cutting size requirement of 170mm. It is equipped with a digital display cut perpendicularity detection gauge to facilitate real-time control of cut quality.

[0018] Chrome plating equipment: It adopts intelligent control area chrome plating equipment, equipped with programmable logic controller (PLC) and high-precision positioning fixture. It can accurately limit the chrome plating area through preset program to avoid chrome plating on bent parts. It is also equipped with an online monitoring system for plating thickness to provide real-time feedback of chrome plating thickness data.

[0019] Bending equipment: High-end CNC fully automatic pipe bending machine is selected, with multi-axis linkage control function, positioning accuracy ≤ ±0.01mm, angle control accuracy ≤ ±0.1°, supports storage and recall of processing parameters, and is equipped with a special parameter calibration kit, including positioning accuracy calibration block, angle calibrator, etc.

[0020] Grinding equipment: High-precision CNC cylindrical grinding machine with stepless spindle speed adjustment, equipped with 800-1000 grit diamond grinding wheels, the grinding wheel runout is controlled within 0.002mm to ensure grinding accuracy and surface quality.

[0021] Testing equipment: Equipped with an electronic micrometer with an accuracy of 0.0001mm, supporting automatic data recording and statistics; a special tool for cross-cut adhesion testing, used for testing the adhesion of chrome plating; and a surface roughness meter, used to verify the surface quality after grinding.

[0022] Auxiliary equipment: Ultrasonic cleaner, power ≥500W, supports water temperature adjustment, equipped with a dedicated cleaning basket to avoid collision damage to parts during cleaning.

[0023] The real number steps are as follows: Blanking process According to the design requirement that the unfolded length of the lubricating oil duct is about 173 mm, combined with the clamping requirements of the numerical control pipe bender, the blanking size is set to 170 mm. Input the size parameters through the programming system of the numerical control shearing machine. Before batch blanking, conduct a first-piece trial cut. After confirming that the size is correct, then start batch processing.

[0024] During the blanking process, control the shearing speed at 50 mm / s to avoid burrs or deformation at the cut due to too fast speed. After shearing, use an angle grinder with a special grinding wheel to preliminarily grind the cut to remove potential burrs.

[0025] Use a digital display cut perpendicularity detection gauge to detect the cut, ensuring that the perpendicularity deviation does not exceed 0.02 mm. At the same time, observe the cut through a magnifying glass for no cracks and oxide scale, and touch the cut edge by hand for no burr feeling. Immediately mark and reject unqualified parts to avoid flowing into the next process.

[0026] Qualified blanking parts are stored in layers using a special material rack. Rubber pads are pasted on the contact surface of the material rack to prevent scratches on the part surface. Make markings in the storage area, indicating the part specifications, blanking date, and inspection status.

[0027] Chromium plating process Part pre-treatment: First, put the qualified blanking parts into an alkaline degreaser and soak them at 60 °C for 15 min to remove surface oil stains. Then pickling with 10% hydrochloric acid solution for 5 min to remove oxide scale. Finally, rinse with deionized water 3 times to ensure no residual impurities on the surface, avoiding affecting the adhesion of the chromium plating layer.

[0028] Clamping and positioning: Install the pre-treated parts on a special chromium plating fixture. Accurately limit the chromium plating range through the fixture, only exposing the 20-mm grinding areas at both ends. Completely wrap the bent parts with high-temperature and corrosion-resistant tape for protection.

[0029] Chromium plating processing: Start the overall chromium plating equipment and set the chromium plating parameters: current density 20 - 25 A / dm², chromium plating temperature 55 - 60 °C, and the chromium plating time is accurately controlled according to the thickness requirement to ensure that the thickness of the chromium plating layer is uniform, with the deviation controlled within the range of ±0.005 mm. During the process, monitor in real time through the on-line monitoring system for the chromium plating layer thickness. Immediately adjust the parameters when any deviation is found.

[0030] Post-treatment and inspection: After chromium plating, put the parts into deionized water and wash for 5 min to remove the residual chromium plating solution on the surface. Use the cross-cut test to detect the adhesion: Use a grid cutter to draw a 10×10 mm grid on the surface of the chromium plating layer, with the depth reaching the substrate, stick a 3M tape and pull it hard. Observe that the chromium plating layer does not peel off as qualified. Use a hardness tester to detect the hardness of the chromium plating layer, ensuring that it reaches HRC35 - 45. Qualified parts are transferred to the next process.

[0031] CNC bending process Equipment calibration: Before bending, the CNC fully automatic pipe bending machine is fully calibrated.

[0032] Parameter settings: Based on the bending angle and bending radius of the lubricating oil conduit and the mechanical properties of 1Cr18Ni9Ti material, preset processing parameters are used to ensure that the actual bending angle is consistent with the design angle.

[0033] Clamping and bending: The qualified chrome-plated parts are loaded into the clamping mechanism of the CNC pipe bending machine. The extended unloading section is used to achieve stable clamping. The machine is started to perform automatic bending processing. During the processing, the machine provides real-time feedback on data such as clamping force and bending angle. If any abnormality occurs, the machine will automatically stop and alarm.

[0034] Preliminary inspection after bending: After bending is completed, visually inspect the bent part for obvious deformation and no damage to the chrome plating. Use calipers to measure the bending angle. If the deviation is within the allowable range, it can proceed to the next process.

[0035] Grinding process Equipment debugging: Install the qualified bent parts on the chuck of the precision cylindrical grinder, adjust the chuck clamping force to avoid clamping deformation; install an 800-1000 grit diamond grinding wheel, and after starting the equipment, use a grinding wheel balancer to check that the grinding wheel runout is ≤0.002mm to ensure grinding stability.

[0036] Grinding parameter settings: Set the grinding parameters according to the thickness of the chrome plating layer and the precision dimensional requirements.

[0037] Step-by-step measurement and calibration: After each grinding process is completed, pause the equipment and use an electronic micrometer to measure the φ5mm dimension at both ends of the part. Measure 4 points at each cross-section and take the average value. Adjust the feed rate of the next process according to the measurement results to ensure that the dimensions gradually approach the design requirements. After fine grinding, the dimensional deviation is controlled within ±0.001mm.

[0038] Surface quality inspection: After grinding, use a surface roughness tester to inspect the surfaces at both ends of the part to ensure that Ra≤0.8μm; observe the surface with a magnifying glass to ensure that there are no grinding scratches, burns or other defects.

[0039] Deburring and cleaning processes Deburring: A combination of ultrasonic deburring and manual grinding is used: First, put the ground parts into an ultrasonic cleaner, add a special deburring cleaning solution, set the water temperature to 50℃, and the cleaning time to 10-15 minutes. Use ultrasonic vibration to remove the tiny burrs and iron filings generated during grinding. For stubborn burrs that are not removed by ultrasonic cleaning, gently grind them with fine sandpaper to ensure that the edges of the parts are smooth and burr-free.

[0040] Cleaning and drying: After deburring, rinse the parts twice in a clean water tank, and then rinse once with deionized water to remove cleaning solution residue; finally, put them in a hot air drying oven and dry them at 80℃ for 10 minutes to ensure that the surface of the parts is clean, free of moisture and residual impurities.

[0041] Quality inspection process Dimensional Inspection: The outer diameter of the part near the bending point is inspected before and after bending. Three inspection sections are selected for each part (one before bending and two after bending). The maximum and minimum dimensions are measured at two points on each section. Each inspection point is measured three times with an electronic micrometer with an accuracy of 0.0001mm, and the average value is taken to ensure that the dimensional change after bending is ≤0.008mm. At the same time, the φ5 at both ends of the part is inspected. Precision dimensions, ensuring they are within tolerance limits.

[0042] Appearance and performance inspection: Visually inspect the parts for defects such as cracks, deformation, and chrome plating peeling; perform a cross-cut adhesion test again to verify that the chrome plating adhesion has not decreased; use a hardness tester to check the hardness of the chrome plating to ensure HRC35-45.

[0043] Conformity assessment and labeling: Parts that meet all test requirements are considered qualified products, and a qualified label is affixed, indicating the product number and test date; unqualified products are classified and marked, the reasons for non-compliance are analyzed, and corrective measures are formulated.

[0044] In summary, the pass rate of lubricating oil conduit processing has increased from 0% in the traditional process to over 95%. The accuracy of key dimensions and surface quality meet the high standards required for aero-engines, reducing assembly rework costs caused by defective parts. The high degree of automation in each process shortens the single-piece processing cycle during mass production compared to the traditional process, meeting the batch delivery requirements of aero-engine parts. There is no need to repair or remake traditional stamping dies, reducing die investment costs. The utilization rate of chrome plating materials is improved, scrap loss is reduced, and the overall production cost is lowered.

[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. 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 basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, 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.

[0046] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A processing technology to improve the yield rate of lubricating oil conduits, characterized in that: The methods and steps include the following: Step 1, Blanking process: For the lubricating conduit with material grade 1Cr18Ni9Ti, diameter 5mm, wall thickness 1mm, and unfolded length of about 173mm, the blanking size is set to 170mm. The blanking size is extended by 90mm compared to the traditional 80mm blanking size. The extended part is used to adapt to the clamping requirements of the CNC pipe bending machine and ensure the stability of the part clamping during the processing. Step 2, Chromium Plating Process: A full-body chromium plating process is adopted instead of the traditional segmented chromium plating process. Through CNC pipe bending data calculation and actual verification, the chromium plating area is precisely limited, requiring only the two ends of the part to meet the φ5 requirement. Chromium plating is applied to the grinding area that requires precision dimensions, avoiding the parts that will be bent later, to prevent the chromium plating layer from developing wrinkles, cracks or peeling during the bending process. Step 3, CNC bending process: Abandoning the traditional stamping process, a CNC pipe bending machine is used for bending. Based on the bending angle, bending radius and material properties of the lubricating pipe, the clamping force, bending speed and bending angle compensation value of the CNC pipe bending machine are preset to accurately bend the chrome-plated parts and control the amount of deformation of the parts during the bending process. Step 4: Grinding Process: After CNC bending is completed, the chrome-plated areas at both ends of the part are ground as a whole. During the grinding process, step-by-step measurement and precision calibration are used to ensure that the φ5 at both ends of the part is properly ground. The precision dimensions conform to the drawing requirements; Step 5, Quality Inspection Process: Before and after CNC bending, inspect the outer diameter of the part near the bending area. The inspection points should include at least the maximum and minimum size inspection points along the circumference to ensure that the dimensional change after bending does not exceed 0.008mm and that all inspected dimensions are within the tolerance range, so that the part processing qualification rate is not less than 90%.

2. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: During the blanking process, the blanking cut must be flat and free of defects such as burrs, cracks, and oxide scale. The perpendicularity deviation of the cut should not exceed 0.02mm to avoid subsequent processing dimensional deviations due to blanking quality issues.

3. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: In the chrome plating process, the chrome plating layer has a uniform thickness with a thickness deviation controlled within ±0.005mm. The hardness of the chrome plating layer is HRC35-45, and the adhesion meets the requirement of no peeling in the cross-cut adhesion test, thus avoiding the impact of poor plating performance on processing accuracy or the service life of parts.

4. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: Before bending, the CNC pipe bending machine needs to be calibrated. The calibration includes the positioning accuracy of the clamping mechanism, the rotation accuracy of the bending spindle, and the accuracy of the angle measurement system, to ensure that the parts are accurately positioned and the bending deformation is uniform and controllable during the processing.

5. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: In the CNC bending process, the bending speed of the CNC pipe bending machine is set to 5-10 mm / s, the clamping force is set to 0.3-0.5 MPa, and the bending angle compensation value is adjusted according to the actual bending test results, with a range of 0.5°-1.5°.

6. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: The grinding process is carried out using a precision cylindrical grinding machine with a grinding wheel grit size of 800-1000 mesh, a grinding speed of 30-40 m / s, and a feed rate of 0.001-0.003 mm / r, ensuring that the surface roughness Ra of the part after grinding is Ra≤0.8μm.

7. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: In the quality inspection process, a micrometer with an accuracy of not less than 0.001 mm is used to measure the size of the inspection points. Each inspection point is measured at least 3 times, and the average value is taken as the final inspection result to ensure the accuracy of the inspection data.

8. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: The CNC pipe bending machine is a fully automatic CNC pipe bending machine with multi-axis linkage control function, positioning accuracy ≤ ±0.01mm, angle control accuracy ≤ ±0.1°, and can accurately realize the bending and forming of lubricating oil conduits.

9. The processing technology for improving the manufacturing pass rate of lubricating oil conduits according to claim 1, characterized in that: After the grinding process is completed, the parts need to be deburred. Ultrasonic cleaning is used to remove iron filings and impurities generated during grinding. The cleaning time is 10-15 minutes to ensure that the surface of the parts is clean and free of residue.

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