Manufacturing process of thin-walled small-diameter oil guide pipe

Abstract

The application discloses a manufacturing process of a thin-wall small-diameter oil guide pipe, and belongs to the technical field of aero-engine part manufacturing, which comprises the following steps: determining a bending influence area through a bending test, and dividing a plastic deformation area, a transition area and a function maintaining area; performing local chromium plating on the function maintaining area only and grinding to form precise fitting sizes at two ends; performing numerical control pipe bending on the oil guide pipe, and compensating pipe bending program parameters on the basis of the test bending; and performing shape correction and length fixing after bending to obtain a finished product pipe. The application has the advantages of improving the qualified rate of the precise sizes at two ends, avoiding plating layer cracking and falling off, reducing bending deformation influence and good machining quality stability.

Description

Technical Field

[0001] This application relates to the field of aero-engine component manufacturing technology, specifically the manufacturing process of thin-walled, small-diameter lubricating oil conduits. Background Technology

[0002] Oil conduits are crucial pipeline components in aero-engines used to transport lubricating oil. Their complex operating environment necessitates not only good corrosion and wear resistance but also high dimensional accuracy at both ends to ensure reliable connection and sealing with adjacent components. For thin-walled, small-diameter oil conduits, the small diameter, thin walls, and poor rigidity make them prone to local instability, cross-sectional deformation, and dimensional drift during forming and machining. This difficulty is further increased when the conduit structure contains both bends and precise dimensional fits at both ends.

[0003] In existing technologies, such lubricating oil conduits typically employ a process route of surface treatment and precision machining followed by bending, with bending methods often including stamping bending or ordinary pipe bending. This process presents several problems in practical applications: Firstly, during the bending process, thin-walled, small-diameter conduits undergo significant plastic deformation at the bending point, transmitting strain to adjacent areas. This can easily lead to changes in the precision fit dimensions at both ends near the bending point, resulting in dimensional deviations and affecting the assembly quality and processing yield of the parts. Secondly, if a coating is pre-formed on the conduit surface, especially near the bending point, the coating is prone to wrinkles, cracks, fragmentation, or even peeling off during subsequent bending due to substrate deformation, thus affecting the surface quality and reliability of the parts. Summary of the Invention

[0004] This application provides a manufacturing process for thin-walled, small-diameter lubricating oil conduits to solve the technical problem that in the prior art, the coating near the bending part of thin-walled, small-diameter lubricating oil conduits is prone to wrinkles, cracks, breakage, or peeling during the bending and forming process, resulting in low processing qualification rate and poor processing quality stability.

[0005] According to one aspect of this application, a manufacturing process for a thin-walled, small-diameter lubricating oil conduit is provided, comprising: S100. Based on the positional relationship between the bent part of the lubricating oil conduit and the precision fit size area at both ends, the bending influence area that affects the precision fit size at both ends during the bending process is determined by bending test. The bending influence area is divided into the plastic deformation area in the middle and the transition area on both sides of the plastic deformation area. The areas at both ends outside the bending influence area are the function retention area. S200: Only the functional retention area is partially chrome-plated, so that the chrome-plating boundary is outside the bending influence area, and the plastic deformation area and transition area remain unplated. S300: Grinding is performed on the functional retention area after partial chrome plating to form the precise fit dimensions at both ends of the lubricating oil conduit; S400, Perform CNC bending on the lubricating oil conduit; S500: The lubricating oil guide tube after CNC bending is shaped and lengthened to obtain the finished lubricating oil guide tube.

[0006] Optionally, the bending test includes the following steps: S110, while keeping the lubricating oil conduit material and CNC bending parameters consistent, set multiple different partition boundary positions along the direction away from the bending part, prepare test pieces accordingly and bend them separately, and detect the size change of the precision fitting area near the bending part and the surface condition of the coating after bending. S120 uses the condition that the size of the precision fit area after bending is within the target tolerance range and the coating is free of wrinkles, cracks, chips or peeling as the judgment condition. The range corresponding to the smallest partition boundary position that meets the judgment condition is determined as the safety boundary of the bending influence zone. The area inside the safety boundary includes the plastic deformation zone and the transition zone, and the area outside the safety boundary is the function retention zone.

[0007] Optionally, in step S400, an inner support structure for supporting the inner wall of the catheter and / or an outer limiting structure for limiting instability on the outer side of the catheter are provided in the plastic deformation zone to reduce the ellipticization and wrinkling deformation of the thin-walled catheter during bending; the inner support structure extends at least partially into the plastic deformation zone and extends into a portion of the transition zone adjacent to the plastic deformation zone to improve the shape retention of the bending zone and boundary area.

[0008] Optionally, step S400 includes the following sub-steps: S410, performing a trial bend on the specimen to obtain the actual bending result after bending; S420, compensating the CNC tube bending program parameters based on the trial bend result, and using the compensated program parameters for subsequent bending.

[0009] Optionally, in step S410, at least three test pieces are first subjected to a first round of trial bending according to the theoretical bending angle, theoretical feed amount, and initial springback compensation value. After the first round of trial bending, the actual bending angle, axial distance from the end reference surface to the bending tangent point, and positional dimensions of the precision fit area at both ends relative to the bending part are measured for each test piece. The measured values ​​of each test piece are compared with the target values ​​to obtain the angle deviation, axial position deviation, and springback deviation, respectively. The average value of each corresponding deviation is taken to obtain the average angle deviation Δθ, average axial position deviation ΔL, and average springback deviation Δθr, respectively.

[0010] Optionally, in step S420, the CNC bending program parameters are corrected in opposite directions based on the average angular deviation Δθ, the average axial position deviation ΔL, and the average springback deviation Δθr. θ0 is the program bending angle used in the first round of bending, θ1 is the program bending angle corrected based on the average angular deviation Δθ, S0 is the feed amount used in the first round of bending, S1 is the feed amount corrected based on the average axial position deviation ΔL, R0 is the springback compensation value used in the first round of bending, and R1 is the springback compensation value corrected based on the average springback deviation Δθr. The program bending angle is corrected to θ1=θ0+k1·Δθ, the feed amount is corrected to S1=S0+k2·ΔL, and the springback compensation value is corrected to R1=R0+k3·Δθr, where k1, k2, and k3 are all compensation coefficients.

[0011] Optionally, in step S420, a second round of trial bending is performed using the modified program bending angle, feed rate, and springback compensation value from the first round of bending. The actual bending angle, the axial distance from the end reference surface to the bending tangent point, and the positional dimensions of the precision fit areas at both ends relative to the bending parts are checked again. If the residual deviation after the second round of trial bending still exceeds 1 / 3 of the target tolerance, the residual deviation is used as the basis for further compensation to continue parameter correction. When the angle deviation and the critical dimension deviation are both no greater than 1 / 3 of the corresponding tolerance zone, the corresponding program bending angle, feed rate, and springback compensation value are determined as formal machining parameters, and the formal machining parameters are used to perform CNC bending on the formal part.

[0012] Optionally, during the first round of compensation, the correction amount for the program bending angle, the correction amount for the feed amount, and the correction amount for the springback compensation are each taken as 70% to 100% of the corresponding average deviation.

[0013] Optionally, step S500 includes verifying the dimensions of the lubricating oil conduit after CNC bending; when the verification result deviates from the target tolerance but is within the correctable range, the lubricating oil conduit is corrected and compensated, and the dimensions are checked again after the correction compensation. The correction compensation adjusts the spatial position relationship of the precision fit areas at both ends by applying a correction effect to the plastic deformation area and its adjacent areas.

[0014] Optionally, the blanking length of the lubricating oil conduit is greater than the length of the finished lubricating oil conduit, so as to form a clamping compensation section at at least one end of the lubricating oil conduit for CNC bending and positioning; in step S400, the clamping position of the CNC bending is set within the clamping compensation section, so that the precision mating area at both ends is not used as the bending clamping area; in step S500, all or part of the clamping compensation section is removed by fixed-length machining to obtain the final length of the finished lubricating oil conduit.

[0015] In summary, this application includes at least one of the following beneficial technical effects: This solution divides the area into a plastic deformation zone and a transition zone, while designating the two ends outside the bending influence zone as functional retention zones. This clearly defines which areas are used to withstand bending plastic deformation and which areas are used to maintain the final precision fit dimensions, thus preventing bending deformation from directly affecting critical precision surfaces. Secondly, only the functional retention zones are locally chrome-plated, with the chrome plating boundary located outside the bending influence zone, keeping the plastic deformation zone and transition zone unplated. This avoids problems such as wrinkles, cracks, fragmentation, or peeling of the plating at the bending location and adjacent areas due to substrate deformation during bending. Thirdly, the functional retention zones after local chrome plating are ground to pre-form the precision fit dimensions at both ends, and then the conduit is formed by subsequent CNC bending. Compared with traditional stamping bending, CNC bending can complete the bending process more smoothly and controllably, reducing the transmission of bending strain to the precision areas at both ends. Finally, after CNC bending, the shape and length are corrected and fixed, further refining and stabilizing the overall spatial shape and end position relationship after bending. It effectively solves the technical problems of thin-walled, small-diameter lubricating conduits that are prone to exceeding the tolerance at both ends after bending and forming, easy damage to the coating in the bending area, and poor overall processing qualification rate and stability in the existing technology.

[0016] In addition to the purposes, features, and advantages described above, this application has other purposes, features, and advantages. A further detailed description of this application will be provided below with reference to the figures. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the lubricating oil conduit. Figure 2 This is a flowchart of the manufacturing process of the thin-walled, small-diameter lubricating oil conduit of this application. Detailed Implementation

[0018] The embodiments of this application are described in detail below with reference to the accompanying drawings; however, this application may be implemented in a variety of different ways as defined and covered below.

[0019] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0020] Reference Figure 1 and Figure 2 This application discloses a manufacturing process for a thin-walled, small-diameter lubricating oil conduit, comprising: S100. Based on the positional relationship between the bent part of the lubricating oil conduit and the precision fit size area at both ends, the bending influence area that affects the precision fit size at both ends during the bending process is determined by bending test. The bending influence area is divided into the plastic deformation area in the middle and the transition area on both sides of the plastic deformation area. The areas at both ends outside the bending influence area are the function retention area. S200: Only the functional retention area is partially chrome-plated, so that the chrome-plating boundary is outside the bending influence area, and the plastic deformation area and transition area remain unplated. S300: Grinding is performed on the functional retention area after partial chrome plating to form the precise fit dimensions at both ends of the lubricating oil conduit; S400, Perform CNC bending on the lubricating oil conduit; S500: The lubricating oil guide tube after CNC bending is shaped and lengthened to obtain the finished lubricating oil guide tube.

[0021] In one embodiment, the part to be processed is an oil conduit in an aero-engine. Such parts are characterized by thin walls, small diameters, and high precision requirements at both ends. Taking the part in this embodiment as an example, the oil conduit can be made of 1Cr18Ni9Ti material, with a conduit diameter of 5mm, a wall thickness of 1mm, and an unfolded length of approximately 173mm. Precision fitting areas requiring dimensional accuracy are provided at both ends of the part, while a bending forming section is provided in the middle. During traditional stamping and bending processes, the tensile deformation generated at the bending section easily propagates to adjacent areas, causing changes in the precision dimensions of the end near the bending section. This is especially true when the transition between a straight section and the curved arc is abrupt, and the straight buffer length is short, making dimensional deviations more likely. Therefore, this embodiment employs a zoned processing method based on the division of the bending influence zone to manufacture this type of conduit.

[0022] In specific implementation, step S100 is performed first. Based on the spatial relationship between the bent portion of the lubricating oil conduit and the precision-fitted dimensional areas at both ends, the range potentially affected by plastic deformation after bending is pre-identified, and this affected range is determined through bending tests. Once determined, the central area that actually bears the bending plastic deformation is designated as the plastic deformation zone; the areas on both sides of the plastic deformation zone, which are affected by bending deformation but are not the main bending parts, are designated as the transition zone; and the two ends outside the bending affected zone, which need to maintain the final precision dimensions and surface condition, are designated as the functional retention zone.

[0023] After completing the area division, step S200 is implemented. In this embodiment, only the functional retention area is partially chrome-plated, with the chrome-plating boundary located outside the bending-affected area, while the plastic deformation area and transition area remain unplated. The reason for this arrangement is that the precision-fitted areas at both ends of the lubricating oil conduit need to have good wear resistance and corrosion resistance in subsequent use, so the plating should still be retained; however, the bending part and its adjacent affected areas will undergo significant deformation during the forming process. If these areas are pre-formed with a hard and brittle plating, wrinkles, cracks, breakage, or peeling are likely to occur during subsequent bending.

[0024] Step S300 is then performed. The functional retention area after partial chrome plating is ground to create precise fit dimensions at both ends of the lubricating oil conduit. This grinding primarily affects the surfaces at both ends of the conduit that will subsequently assemble with adjacent components. Grinding ensures the end dimensions meet design requirements and guarantees the surface quality of the mating surfaces. Since the chrome plating in the previous step was limited to the functional retention area, the grinding is concentrated at both ends of the conduit and will not affect areas requiring subsequent bending deformation. After this process, the ends of the conduit first achieve precise fit dimensions that meet assembly requirements, while the central bending area retains a substrate state suitable for subsequent forming.

[0025] Next, step S400 is performed to CNC bend the lubricating oil conduit. In this embodiment, CNC bending is used instead of traditional stamping bending, so that the conduit is formed according to a predetermined bending shape. Compared with stamping bending, CNC bending has more stable deformation and more controllable trajectory during the forming process, which can reduce the influence of bending on adjacent precision dimension areas, thereby helping to maintain the precision fit dimensions that have been machined at both ends of the conduit.

[0026] Finally, step S500 is implemented. After the conduit is formed by CNC bending, it is shaped and length-determined to obtain the finished lubricating oil conduit. Shaping corrects the overall spatial shape and relative positional relationship of the ends after bending, while length determination ensures the total length of the conduit meets the finished product size requirements. Through the above process route, this embodiment effectively reduces the adverse effects of bending forming on the precision fit dimensions of the ends, while avoiding damage to the plating in the bending area during forming, thereby significantly improving the processing pass rate and processing stability of thin-walled, small-diameter lubricating oil conduits. This process route has increased the first-pass yield of parts from nearly 0% to over 90%, and its effectiveness has been verified in multiple batches of products made of the same material.

[0027] In one embodiment, the bending test includes the following steps: S110, while keeping the lubricating oil conduit material and CNC bending parameters consistent, set multiple different partition boundary positions along the direction away from the bending part, prepare test pieces accordingly and bend them separately, and detect the size change of the precision fitting area near the bending part and the surface condition of the coating after bending. S120 uses the condition that the size of the precision fit area after bending is within the target tolerance range and the coating is free of wrinkles, cracks, chips or peeling as the judgment condition. The range corresponding to the smallest partition boundary position that meets the judgment condition is determined as the safety boundary of the bending influence zone. The area inside the safety boundary includes the plastic deformation zone and the transition zone, and the area outside the safety boundary is the function retention zone.

[0028] To determine the actual extent of the impact of the oil conduit on the precision-fitted areas at both ends during the bending process, a bending test was first conducted. The test specimen was an oil conduit identical to the final part, with the geometry, bending direction, and target bending shape all consistent with the final part. During the test, the material, diameter, wall thickness, and CNC bending conditions of each specimen were kept consistent; only the boundary positions of the partitions were changed to compare the effects of different boundary positions on the dimensional stability and surface condition of the precision-fitted areas at the ends.

[0029] In practice, using the bent section as a reference, multiple different partition boundary positions are pre-set sequentially along the direction away from the bent section. These different partition boundary positions can be understood as follows: as the bent section extends towards both ends, a certain position is assumed to be the outer boundary of the bending influence zone, thus obtaining multiple sets of candidate boundaries. For each set of candidate boundaries, a corresponding specimen is prepared and bent according to the same bending requirements. To ensure the comparability of experimental conclusions, all process conditions are kept consistent between different specimens except for the partition boundary positions.

[0030] After each specimen is bent, the precision-fit area near the bending point is inspected. The inspection includes two parts: first, dimensional changes, to confirm whether the precision-fit area remains within the target tolerance range after bending; second, the surface condition of the coating, to confirm whether there are defects such as wrinkles, cracks, chips, or peeling near the boundary. Dimensional inspection can be performed by setting inspection points near the bending point and comparing the corresponding dimensions before and after bending; the coating condition is determined by observing the surface condition near the boundary and the area adjacent to the bending point.

[0031] A candidate boundary position is considered valid when the specimen meets the following conditions after bending: Firstly, the dimensions of the precision-fit area near the bending point remain within the target tolerance range; secondly, the coating near the boundary does not exhibit wrinkles, cracks, fragmentation, or peeling. After comparing each group of candidate boundary positions, the smallest boundary position that satisfies the above criteria is selected, and the area corresponding to this boundary position is determined as the safe boundary of the bending influence zone. Using the smallest boundary position that meets the conditions as the final result ensures that the functional retention zone is as close as possible to the bending point while maintaining dimensional and coating quality, thus balancing processing feasibility and process economy. After determining the safe boundary, the central area within the safe boundary is designated as the plastic deformation zone, the areas on both sides of the plastic deformation zone between the safe boundary and the boundary are designated as the transition zone, and the two ends outside the safe boundary are designated as the functional retention zone.

[0032] In one embodiment, in step S400, an inner support structure for supporting the inner wall of the catheter and / or an outer limiting structure for limiting instability on the outer side of the catheter are provided in the plastic deformation zone to reduce the ellipticization and wrinkling deformation of the thin-walled catheter during bending; the inner support structure extends at least partially into the plastic deformation zone and extends into a portion of the transition zone adjacent to the plastic deformation zone to improve the shape retention of the bending zone and the boundary area.

[0033] Since the part to be processed is a thin-walled, small-diameter conduit, during the bending process, phenomena such as cross-sectional out-of-roundness, local instability on the outer side, or wrinkling on the inner side are prone to occur in the plastic deformation zone, and shape fluctuations are also likely to occur at the boundary between the plastic deformation zone and the transition zone. Therefore, in step S400, an inner support structure for supporting the inner wall of the conduit and / or an outer limiting structure for limiting instability on the outer side of the conduit are provided in the plastic deformation zone to reduce ellipticization and wrinkling deformation during the bending process.

[0034] The inner support structure is arranged within the conduit's inner lumen to support the inner wall region, which is prone to instability during bending, thereby improving the conduit's cross-sectional shape retention. The outer limiting structure is located on the outside of the conduit to limit the outer contour deviation or local instability during bending, ensuring the conduit completes bending along a predetermined shape. Furthermore, the inner support structure extends at least partially into the plastic deformation zone and into the adjacent transition zone to improve the shape retention of the bending and boundary areas, making the bending deformation transition more smoothly and stably from the plastic deformation zone outwards. By incorporating the inner support structure and / or the outer limiting structure, the stability of the bending process of thin-walled, small-diameter lubricating oil conduits can be improved.

[0035] In one implementation, step S400 includes the following sub-steps: S410. Perform a trial bend on the specimen to obtain the actual bending result after bending. S420. Based on the trial bending results, compensate the CNC tube bending program parameters, and use the compensated program parameters for subsequent bending and forming.

[0036] Step S400 does not directly use fixed parameters to CNC bend the final part. Instead, it first obtains the actual bending results through trial bending, and then compensates the CNC bending program parameters based on the trial bending results. Specifically, step S410 is first implemented to perform a trial bending on the test piece, allowing the test piece to complete the preliminary forming according to the predetermined bending requirements, and obtaining the actual angle, position, and shape results after bending. Since thin-walled small-diameter conduits are easily affected by material springback, local deformation, and forming stability during the bending process, there is usually a deviation between the actual bending results and the theoretical settings. Therefore, relying solely on theoretical parameters is insufficient to directly guarantee the machining accuracy of the final part. Based on this, step S420 is then implemented to correct the CNC bending program parameters according to the trial bending results, and the compensated program parameters are used for subsequent bending forming. By first performing trial bending and then compensating, the final bending forming can be based on actual experimental results, thereby improving the accuracy and stability of the bending processing of thin-walled small-diameter lubricating conduits.

[0037] In one embodiment, in step S410, at least three test pieces are first subjected to a first round of trial bending according to the theoretical bending angle, theoretical feed amount, and initial springback compensation value. After the first round of trial bending, the actual bending angle, axial distance from the end reference surface to the bending tangent point, and positional dimensions of the precision fit area at both ends relative to the bending part of each test piece are measured respectively. The measured values ​​of each test piece are compared with the target values ​​to obtain the angle deviation, axial position deviation, and springback deviation respectively. The average value of each corresponding deviation is taken to obtain the average angle deviation Δθ, average axial position deviation ΔL, and average springback deviation Δθr respectively.

[0038] In practice, the theoretical bending angle, theoretical feed amount, and initial springback compensation value are first preset based on the target bending shape of the conduit. This set of parameters is then used to perform a first round of trial bending on at least three specimens. Using multiple specimens instead of a single specimen helps reduce the impact of individual specimen errors on subsequent parameter corrections and improves the representativeness of the trial bending results. After the first round of trial bending, the actual bending angle, axial distance from the end reference surface to the bending tangent point, and positional dimensions of the precision-fit areas at both ends relative to the bending part are measured for each specimen. These measured values ​​are then compared with the target values. The actual bending angle reflects the angular forming of the conduit after bending, the axial distance reflects the positional relationship between the bending part and the end reference, and the positional dimensions of the precision-fit areas at both ends relative to the bending part reflect the spatial positional change of the key mating areas after bending. By comparing these results, the angle deviation, axial positional deviation, and springback deviation can be obtained. The average value of the corresponding deviations for each specimen is then used as the basis for subsequent CNC bending program parameter corrections. This setup allows subsequent parameter adjustments to be based on the average forming results of multiple specimens, thereby improving the stability and consistency of the bending process for the final parts.

[0039] In one embodiment, in step S420, the CNC bending program parameters are corrected in opposite directions based on the average angular deviation Δθ, the average axial position deviation ΔL, and the average springback deviation Δθr. Here, θ0 is the program bending angle used in the first trial bend, θ1 is the program bending angle corrected based on the average angular deviation Δθ, S0 is the feed amount used in the first trial bend, S1 is the feed amount corrected based on the average axial position deviation ΔL, R0 is the springback compensation value used in the first trial bend, and R1 is the springback compensation value corrected based on the average springback deviation Δθr. The program bending angle is corrected to θ1 = θ0 + k1·Δθ, the feed amount is corrected to S1 = S0 + k2·ΔL, and the springback compensation value is corrected to R1 = R0 + k3·Δθr, where k1, k2, and k3 are all compensation coefficients.

[0040] Step S420 is a process of specifically correcting the CNC pipe bending program parameters after obtaining the average angular deviation Δθ, average axial position deviation ΔL, and average springback deviation Δθr in step S410. Because thin-walled, small-diameter lubricating conduits are simultaneously affected by material springback, local deformation, and bending entanglement during bending, the theoretical parameters used in the first trial bending are usually insufficient to directly meet the processing requirements of the final part. Therefore, it is necessary to correct the program bending angle, feed rate, and springback compensation value based on the deviation results obtained from the trial bending, so that the subsequent bending results are closer to the target requirements.

[0041] Specifically, the correction of the program bending angle is used to correct the angle result after the duct is bent. θ0 represents the program bending angle used in the first round of bending, and θ1 represents the corrected program bending angle. When the average angle deviation Δθ is obtained after the first round of bending, the program bending angle is corrected in the opposite direction based on this deviation. If the actual bending angle is less than the target bending angle, it indicates insufficient bending, and the program bending angle needs to be appropriately increased; if the actual bending angle is greater than the target bending angle, it indicates excessive bending, and the program bending angle needs to be appropriately decreased. Through the relationship θ1=θ0+k1·Δθ, a correspondence can be established between the bending angle correction and the average angle deviation, where the compensation coefficient k1 is used to control the correction range, so that the parameter adjustment can reflect the bending result while avoiding excessive correction that would lead to new deviations.

[0042] The feed amount correction is mainly used to correct the axial positional relationship between the bent section and the end of the conduit. S0 represents the feed amount used in the first trial bend, and S1 represents the corrected feed amount. Since the feed amount directly affects the bending tangent point and the spatial distribution of the bent section relative to the end reference during CNC pipe bending, the feed amount needs to be corrected based on the average axial positional deviation ΔL obtained in the first trial bend. The formula S1 = S0 + k2·ΔL allows the corrected feed amount to be closer to the target position requirement. The compensation coefficient k2 is used to adjust the feed amount correction range, ensuring that the bent conduit meets overall shape requirements while also maintaining the positional accuracy of the precision-fitted areas at both ends relative to the bent section.

[0043] The springback compensation value correction is used to correct the impact of material springback on the forming result. R0 represents the springback compensation value used in the first round of trial bending, and R1 represents the corrected springback compensation value. For thin-walled, small-diameter conduits, the material will experience a certain amount of springback after bending and unloading. If the springback is not compensated, the final angle and positional relationship after bending are prone to deviate from the target requirements. After obtaining the average springback deviation Δθr through the first round of trial bending, the springback compensation value is corrected in the opposite direction to form the corrected springback compensation value R1. Through the relationship R1=R0+k3·Δθr, the preset springback compensation amount in the program can be made to correspond with the actual springback measured by the trial bending. Among them, the compensation coefficient k3 is used to control the adjustment range of the springback compensation value, so that the correction of material springback during subsequent bending forming is more in line with the actual forming law.

[0044] In this embodiment, the program bending angle, feed rate, and springback compensation value are not modified in isolation, but rather act as a set of related parameters in the subsequent bending and forming process. Specifically, the program bending angle primarily affects the angle result after the guide tube is bent; the feed rate primarily affects the axial positional relationship between the bent portion and the end reference; and the springback compensation value is used to reduce the impact of material unloading springback on the final forming result. By synchronously modifying these three types of parameters, the CNC tube bending program can be transformed from the theoretical parameter state of the initial trial bending to a compensated parameter state that better conforms to the actual forming law, thereby providing a more accurate program basis for subsequent formal processing.

[0045] In one implementation, in step S420, a second round of trial bending is performed using the modified program bending angle, feed rate, and springback compensation value from the first round of bending. The actual bending angle, the axial distance from the end reference surface to the bending tangent point, and the positional dimensions of the precision fit areas at both ends relative to the bending parts are checked again. When the residual deviation after the second round of trial bending still exceeds 1 / 3 of the target tolerance, the residual deviation is used as the basis for further compensation to continue parameter correction. When the angle deviation and the critical dimension deviation are both no greater than 1 / 3 of the corresponding tolerance zone, the corresponding program bending angle, feed rate, and springback compensation value are determined as formal machining parameters, and the formal machining parameters are used to perform CNC bending on the formal part.

[0046] After the first round of parameter correction, a second round of trial bending is performed using the corrected program bending angle, feed rate, and springback compensation value. Following the second round of trial bending, the actual bending angle, the axial distance from the end reference surface to the bending tangent point, and the relative positional dimensions of the precision-fitted areas at both ends relative to the bending portion are checked again. The results are compared with the target values ​​to obtain the residual deviation. If the residual deviation still exceeds 1 / 3 of the target tolerance, it indicates that the existing program parameters still cannot meet the processing requirements, and the program parameters need to be further corrected based on the residual deviation. If the angle deviation and critical dimension deviation are both no greater than 1 / 3 of the corresponding tolerance zone, it indicates that the current program parameters can stably meet the forming requirements. At this point, the corresponding program bending angle, feed rate, and springback compensation value are determined as the formal processing parameters, and this set of formal processing parameters is used to perform CNC bending on the formal part. Through the above two-round trial bending and residual deviation correction process, the formal processing parameters can be established on the basis of gradually approaching the target value, thereby improving the accuracy and stability of bending and forming of thin-walled, small-diameter lubricating conduits.

[0047] In one implementation, during the first round of compensation, the program bending angle correction, feed amount correction, and springback compensation correction are each taken as 70% to 100% of the corresponding average deviation.

[0048] The initial compensation does not directly incorporate all the average angle deviation, average axial position deviation, and average springback deviation obtained from the first trial bend into the CNC bending program. Instead, it controls the program's bending angle correction, feed rate correction, and springback compensation correction within 70% to 100% of their respective average deviations. This is because while the deviations obtained from the first trial bend reflect the difference between the actual forming result and the target result, these differences may still include factors such as material batch fluctuations, single-batch forming discreteness, and inspection errors. Directly correcting to over 100% could easily lead to excessive program parameter adjustments, causing new deviations. Limiting the initial compensation to 70% to 100% of the corresponding average deviation allows for a buffer margin for parameter adjustments while ensuring the correct correction direction. This allows for a smooth transition of the program's bending angle, feed rate, and springback compensation values ​​from theoretical parameters to actual adaptive parameters, thereby improving the stability of subsequent second-round trial bends and formal bending forming.

[0049] In one implementation, step S500 further includes the following steps: The dimensions of the lubricating oil conduit after CNC bending are checked. When the check result deviates from the target tolerance but is within the correctable range, the lubricating oil conduit is corrected and compensated. After the correction and compensation, the dimensions are checked again. The correction and compensation adjusts the spatial position relationship of the precision fit area at both ends by applying a correction effect to the plastic deformation area and its adjacent areas.

[0050] After CNC bending, the dimensions of the lubricating oil guide tube are checked. This check includes the actual bending angle, the axial distance from the end reference surface to the bending tangent point, and the positional dimensions of the precision-fit areas at both ends relative to the bent portion. If the check results meet the target tolerance requirements, the tube proceeds to the subsequent length-fixing process. If the check results deviate from the target tolerance but are still within the correctable range, the lubricating oil guide tube undergoes shape correction compensation. Shape correction compensation primarily restores the spatial relationship between the bent portion and the precision-fit areas at both ends to the target state by applying a corrective effect to the plastic deformation zone and its adjacent areas, without directly re-machining the precision-fit surfaces at both ends. After shape correction compensation, a second dimensional inspection is performed to confirm whether the lubricating oil guide tube meets the target tolerance requirements after correction. By adding dimensional checks and shape correction compensation after CNC bending, residual deviations caused by bending can be further corrected, improving the positional accuracy of the precision-fit areas at both ends and the overall forming quality, thereby improving the processing stability and yield rate of the finished lubricating oil guide tube.

[0051] In one embodiment, the blanking length of the lubricating oil conduit is greater than the length of the finished lubricating oil conduit, so as to form a clamping compensation section at at least one end of the lubricating oil conduit for CNC bending and positioning; in step S400, the clamping position of the CNC bending is set within the clamping compensation section, so that the precision mating area at both ends is not used as the bending clamping area; in step S500, all or part of the clamping compensation section is removed by fixed-length machining to obtain the final length of the finished lubricating oil conduit.

[0052] To meet the clamping and positioning requirements during CNC pipe bending, the blanking length of the lubricating oil conduit is longer than the final length of the finished lubricating oil conduit, thus forming a clamping compensation section at at least one end of the lubricating oil conduit. The clamping compensation section provides clamping and positioning space during CNC pipe bending, concentrating the clamping action of the bending equipment within the compensation section rather than directly acting on the precision-fit areas at both ends. This design is because directly clamping in the precision-fit areas at both ends can easily affect the already machined surface quality and dimensional accuracy, and may also introduce additional deformation during clamping, which is detrimental to maintaining the subsequent precision fit requirements. By setting the clamping position within the clamping compensation section, the clamping action area of ​​the bending pipe can be separated from the precision-fit area that needs to be retained. After completing the CNC pipe bending and necessary straightening, all or part of the clamping compensation section is removed through fixed-length machining, allowing the lubricating oil conduit to reach the final length required for the finished product. This method satisfies the process implementation conditions of CNC pipe bending while avoiding adverse effects of the clamping process on critical areas of the finished product, thereby improving the stability of the thin-walled, small-diameter lubricating oil conduit processing and the quality of the finished product.

[0053] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A manufacturing process for thin-walled, small-diameter lubricating oil conduits, characterized in that, include: S100. Based on the positional relationship between the bent portion of the lubricating oil conduit and the precision fit dimensions at both ends, a bending test is conducted to determine the bending influence zone that affects the precision fit dimensions at both ends during the bending process. The bending influence zone is divided into a plastic deformation zone in the middle and transition zones on both sides of the plastic deformation zone. The areas at both ends outside the bending influence zone are the function retention zones. S200. Only the function retention zones are partially chrome-plated, ensuring that the chrome-plating boundary is outside the bending influence zone, and the plastic deformation zone and transition zone remain unplated. S300. The function retention zones after partial chrome plating are ground to form the precision fit dimensions at both ends of the lubricating oil conduit. S400. The lubricating oil conduit is CNC bent. S500. The CNC-bent lubricating oil conduit is straightened and lengthened to obtain the finished lubricating oil conduit.

2. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 1, characterized in that: The bending test includes the following steps: S110, while keeping the lubricating oil conduit material and CNC bending parameters consistent, set multiple different partition boundary positions along the direction away from the bending part, prepare test pieces accordingly and bend them separately, and detect the size change of the precision fitting area near the bending part and the surface condition of the coating after bending. S120 uses the condition that the size of the precision fit area after bending is within the target tolerance range and the coating is free of wrinkles, cracks, chips or peeling as the judgment condition. The range corresponding to the smallest partition boundary position that meets the judgment condition is determined as the safety boundary of the bending influence zone. The area inside the safety boundary includes the plastic deformation zone and the transition zone, and the area outside the safety boundary is the function retention zone.

3. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 1, characterized in that: In step S400, before CNC bending the lubricating oil conduit, an inner support structure for supporting the inner wall of the conduit and / or an outer limiting structure for limiting the instability of the outer side of the conduit are provided in the plastic deformation zone to reduce the ellipticization and wrinkling deformation of the thin-walled conduit during the bending process; the inner support structure extends at least partially into the plastic deformation zone and extends into the transition zone adjacent to the plastic deformation zone to improve the shape retention of the bending zone and the boundary area.

4. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 1, characterized in that: Step S400 includes the following sub-steps: S410, perform a trial bend on the specimen to obtain the actual bending result after bending; S420, compensate the CNC bending program parameters according to the trial bend result, and use the compensated program parameters for subsequent bending.

5. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 4, characterized in that: In step S410, at least three test pieces are first subjected to a first round of trial bending according to the theoretical bending angle, theoretical feed amount, and initial springback compensation value. After the first round of trial bending, the actual bending angle, axial distance from the end reference surface to the bending tangent point, and positional dimensions of the precision fit area at both ends relative to the bending part are measured for each test piece. The measured values ​​of each test piece are compared with the target values ​​to obtain the angle deviation, axial position deviation, and springback deviation, respectively. The average value of each corresponding deviation is taken to obtain the average angle deviation Δθ, average axial position deviation ΔL, and average springback deviation Δθr, respectively.

6. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 5, characterized in that: In step S420, the CNC pipe bending program parameters are corrected in opposite directions based on the average angular deviation Δθ, the average axial position deviation ΔL, and the average springback deviation Δθr. The program bending angle is corrected to θ1=θ0+k1·Δθ, the feed amount is corrected to S1=S0+k2·ΔL, and the springback compensation value is corrected to R1=R0+k3·Δθr. θ0 is the program bending angle used in the first round of bending, θ1 is the program bending angle corrected according to the average angle deviation Δθ, S0 is the feed amount used in the first round of bending, S1 is the feed amount corrected according to the average axial position deviation ΔL, R0 is the springback compensation value used in the first round of bending, R1 is the springback compensation value corrected according to the average springback deviation Δθr, and k1, k2, and k3 are all compensation coefficients.

7. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 6, characterized in that: In step S420, a second round of trial bending is performed using the modified program bending angle, feed rate, and springback compensation value from the first round. The actual bending angle, the axial distance from the end reference surface to the bending tangent point, and the positional dimensions of the precision fit areas at both ends relative to the bending parts are checked again. If the residual deviation after the second round of trial bending still exceeds 1 / 3 of the target tolerance, the residual deviation is used as the basis for further compensation to continue parameter correction. When the angle deviation and dimensional deviation are both no greater than 1 / 3 of the corresponding tolerance zone, the corresponding program bending angle, feed rate, and springback compensation value are determined as the formal machining parameters, and the formal machining parameters are used to perform CNC bending on the formal part.

8. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 6, characterized in that: During the first round of compensation, the correction amounts for program bending angle, feed amount, and springback compensation are taken as 70% to 100% of the corresponding average deviation.

9. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 1, characterized in that: Step S500 includes verifying the dimensions of the lubricating oil conduit after CNC bending; when the verification result deviates from the target tolerance but is within the correctable range, the lubricating oil conduit is corrected and compensated, and the dimensions are checked again after the correction and compensation. The correction and compensation adjusts the spatial position relationship of the precision fit areas at both ends by applying a correction effect to the plastic deformation area and its adjacent areas.

10. The manufacturing process of the thin-walled small-diameter lubricating oil conduit according to claim 1, characterized in that: The length of the lubricating oil conduit is greater than the length of the finished lubricating oil conduit, so that a clamping compensation section for CNC bending and positioning is formed at at least one end of the lubricating oil conduit; in step S400, the clamping position of the CNC bending is set within the clamping compensation section, so that the precision fit area at both ends is not used as the bending clamping area; in step S500, all or part of the clamping compensation section is removed by fixed-length machining to obtain the final length of the finished lubricating oil conduit.

Images