Oil duct optimization design method based on additive manufacturing and oil duct

Abstract

The invention discloses an oil duct optimization design method based on additive manufacturing and an oil duct. The method comprises the following steps: firstly, performing feature recognition on an original oil duct model, positioning a process hole, a blind hole and a runner inlet and outlet, and recognizing a to-be-optimized region based on a printing direction; reconstructing an oil duct path by using a quasi-uniform B-spline curve, and minimizing the flow resistance while satisfying the suspension angle constraint through shape optimization; in the path key area, topological optimization is carried out with the material volume as the constraint and the minimum pressure drop as the target, and an efficient flow guide structure is generated; and finally, through model reconstruction and performance verification, a metal additive manufacturing technology is adopted for integrated forming. The oil duct designed through the method is an integrally-formed metal component, no auxiliary hole or supporting structure exists in the oil duct, the flow channel is smooth and has the optimized flow guide characteristic, the leakage risk is fundamentally eliminated, and flowing pressure loss, noise and vibration are remarkably reduced. According to the invention, deep collaborative optimization of fluid performance, structural reliability and additive manufacturing manufacturability is realized.

Description

Technical Field

[0001] This invention relates to the field of mechanical design and manufacturing technology, specifically to an oil passage optimization design method and oil passage based on additive manufacturing. Background Technology

[0002] This section provides only background information related to this application to enable those skilled in the art to understand this application more thoroughly and accurately, and it is not necessarily prior art.

[0003] Armored vehicle transmission systems operate under harsh conditions involving wide loads, wide temperature ranges, strong impacts, and complex vibrations. The performance of their internal lubrication and hydraulic channels directly affects the reliability and efficiency of the transmission. Currently, transmission box components with hydraulic channels exceeding 500mm in size primarily utilize precision casting combined with machining to form their complex internal hydraulic systems. This traditional process has several inherent drawbacks: First, due to the limitations of mold core pulling and tool accessibility, the oil channel layout is greatly simplified, and right-angle or non-orthogonal sharp turns are often used for transition, which easily generates severe fluid turbulence and eddies, resulting in increased energy loss (pressure drop), oil heating, and unstable flow noise and vibration.

[0004] Secondly, to facilitate casting and machining, process holes and blind holes must be installed in the oil passages, which are then sealed with plugs. Under the long-term strong impact and vibration of vehicles, these plug seals are prone to failure, causing oil leakage, which is one of the key weak links affecting the reliability of the equipment.

[0005] Finally, solid parts of large castings are prone to shrinkage defects during solidification, which affect the strength of the casting and pose potential quality risks.

[0006] Additive manufacturing (3D printing) technology, especially metal powder bed fusion technology, offers near-limitless design freedom, near-net-shape forming capabilities, and excellent mechanical properties, providing a revolutionary solution for the integrated manufacturing of complex internal flow channels. However, designing flow channels that fully leverage the advantages of additive manufacturing while meeting specific fluid performance requirements and possessing good printability (e.g., avoiding internal supports) remains a systemic engineering problem that urgently needs to be solved. Current technologies lack a complete design methodology chain, encompassing manufacturability identification, performance optimization, and process implementation, to address the aforementioned problems inherent in traditional oil passages. Summary of the Invention

[0007] The present invention aims to overcome the shortcomings of the prior art and provide an oil passage optimization design method based on additive manufacturing and a high-performance oil passage manufactured therefrom.

[0008] To achieve the above objectives, in a first aspect, the present invention discloses an oil passage optimization design method based on additive manufacturing, comprising the following steps: S1. Feature Recognition: Obtain the original three-dimensional model of the oil channel to be optimized, identify the process holes, blind holes and flow channel inlets and outlets in the model, and identify the area to be optimized in the flow channel based on the preset additive manufacturing printing direction; S2. Path optimization and manufacturability design: After removing process holes and blind holes in the oil duct, the oil duct path of the region to be optimized is reconstructed based on a quasi-uniform B-spline curve; the curve parameters are adjusted so that the reconstructed path meets the overhang angle constraint of additive manufacturing, and the curve shape is optimized to obtain the optimized path with the goal of reducing flow resistance. S3. Local oil passage topology optimization: Extract the design domain in the critical flow region of the optimization path, use the actual working conditions as boundary conditions, the volume of material in the flow domain as constraint conditions, and the minimum fluid pressure drop in the design domain as the optimization objective to perform topology optimization and obtain the local configuration with optimized material distribution. S4. Model Reconstruction and Performance Verification: The local configuration is reconstructed into a geometric model and integrated with the optimization path to form a complete optimized oil passage model, which is then verified by fluid simulation. S5. Integrated Additive Manufacturing: The optimized oil passage model that has passed verification is given an outer diameter allowance and external support, and is integrally formed using metal additive manufacturing technology. The resulting oil passage has no internal support structure.

[0009] According to an example of the present invention, in step S1, the region to be optimized is: a flow channel region where the overhang angle is less than a first preset threshold and the aperture is greater than a second preset threshold.

[0010] Preferably, the first preset threshold is 40° and the second preset threshold is 10mm.

[0011] According to an example of the present invention, in step S2, the quasi-uniform B-spline curve is a fourth-order or higher curve; the shape optimization is completed iteratively through fluid simulation analysis, with the control point coordinates of the curve as the design variable, the overhang angle constraint as the geometric constraint, and the minimum total pressure drop of the flow channel as the optimization objective; wherein, the overhang angle of the oil channel is greater than 40°.

[0012] According to an example of the present invention, in step S2, the following algorithm is used for path optimization: Path representation: , , Where C(u) is a parametric curve defined by a B-spline, and u is a variable at any point on the path curve; N i,p (μ) is a basis function used to pass through control point P. i Fit a continuous path, where P0 is the starting point of the path, P n The endpoint of the path; Path constraints: Where Z'(u) is the rate of change of the curve in the Z direction at u, and D(C(u)) is the aperture function along the path (i.e., the cross-sectional diameter at a point on the path). Objective function: ;in, J(P) is the objective function, representing the pressure loss under the design path; W1 is the weighting coefficient of the path length, i.e., the pressure loss along the path; and W2 is the weighting coefficient of the local pressure loss caused by the change of the path.

[0013] According to an example of the present invention, in step S4, the reconstruction is based on the material density cloud map generated by topology optimization, and through isosurface extraction and geometric smoothing, a local flow channel structure with a machinable surface is generated.

[0014] On the other hand, the present invention also discloses a transmission device oil passage, which is manufactured by the aforementioned oil passage optimization design method based on additive manufacturing.

[0015] According to one example of the present invention, the oil passage is a one-piece formed metal component with no internal process holes or sealing plugs, and the overhang angle of all internal flow channel surfaces is greater than 40°.

[0016] According to one example of the invention, the oil passage includes a flow guiding structure generated by topology optimization design at the location where the flow direction changes or the cross-section changes.

[0017] The following benefits can be obtained by adopting this technical solution: (1) Completely eliminates sealing links such as process holes and plugs, making the oil passage a complete and sealed cavity, eliminating oil leakage caused by seal failure under vibration and impact, and is particularly suitable for military and heavy equipment with extremely stringent reliability requirements.

[0018] (2) By optimizing the oil passage path through high-order B-spline curves and combining topology optimization to generate better flow guiding structures locally, the eddy current and flow separation can be significantly reduced, the transmission efficiency can be improved, and the fluid noise and vibration levels can be significantly reduced.

[0019] (3) The absence of internal support is treated as a hard constraint and guaranteed through path optimization. This avoids the difficult problem of removing internal support after printing, simplifies the post-processing process, and improves the yield. It also avoids the impact of support residue on the quality of the inner wall of the flow channel, and achieves near-net-shape forming of complex internal flow channels.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a general flowchart of the oil passage optimization design method provided in the embodiments of the present invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. Example

[0024] This embodiment takes a main oil passage in the integrated transmission device of a certain type of armored vehicle, which is responsible for providing lubrication to bearings and gears, as the object, and demonstrates the entire process of redesigning and manufacturing using the method of the present invention.

[0025] S1. Problem Analysis and Feature Recognition The designers first obtained a 3D model of the transmission housing and the existing casting oil channels from existing CAD drawings. Analysis revealed that the existing oil channels, designed for casting, contained two right-angle bends (90°) and one M12 threaded blind hole for installing a process plug. The inlet and outlet positions of the oil channels were fixed. Laser powder bed fusion (LPBF) technology was chosen for manufacturing, and the printing direction was set to the natural vertical direction (Z-axis) of the housing within the equipment.

[0026] By manually identifying or analyzing the model using software, the overhang angle analysis threshold was set to 40°, and the aperture filtering threshold was set to 10mm. The areas to be optimized were identified: the overhang angles of the inner wall areas of the two right-angle bends were close to 0°, much less than 40°, and the equivalent diameter of the flow channel at these locations reached 12mm, which are typical areas that require internal support for printing.

[0027] S2, Global Path Reconstruction and Shape Optimization The designers removed the threaded blind hole feature. Subsequently, a fifth-order quasi-uniform B-spline curve was used as the new framework to redesign the oil passage path from inlet to outlet. Initially, the control points of the curve were roughly arranged along the original path. In the CAD software, the overhang angle (i.e., the angle between the tangent at that point and the horizontal plane) of each point on the new path was monitored in real time using visualization tools. By manually or automatically adjusting the Z-coordinate of the control points using scripts, the overhang angle at any point along the entire path was ensured to be greater than 45°, thus meeting the self-support requirement.

[0028] Next, we proceed to the automated shape optimization stage. An optimization workflow was built in the ANSYS Workbench environment: 15 parameters (X, Y, Z coordinates) of 5 key control points were set as design variables; the geometric constraint was set as the overhang angle of the lowest point of the path > 45°; the optimization objective was set as minimizing the total static pressure loss between the oil passage inlet and outlet at rated speed (corresponding to a lubricating oil flow rate of 80 L / min and a temperature of 100°C). The following algorithm was used for path optimization: Path representation: , , Where C(u) is a parametric curve defined by a B-spline, and u is a variable at any point on the path curve; N i,p (μ) is a basis function used to pass through control point P. i Fit a continuous path, where P0 is the starting point of the path, P n The endpoint of the path; Path constraints: Where Z'(u) is the rate of change of the curve in the Z direction at u, and D(C(u)) is the aperture function along the path (i.e., the cross-sectional diameter at a point on the path). Objective function: ;in, J(P) is the objective function, representing the pressure loss under the design path; W1 is the weighting coefficient of the path length, i.e., the pressure loss along the path; and W2 is the weighting coefficient of the local pressure loss caused by the change of the path.

[0029] The optimization process automatically performed approximately 50 iterations. Each iteration automatically updated the curve, generated the flow channel entity (setting a circular cross-section with a diameter of 12mm), and performed CFD mesh generation and solution. Ultimately, a set of optimal control point coordinates was found. This optimized path forms a smooth "S"-shaped curve in space, perfectly avoiding internal support requirements while theoretically reducing pressure drop by approximately 25% compared to the initial right-angled path.

[0030] S3, Key Region Topology Optimization In the global optimization path, there is a point where the main oil flow needs to be smoothly split into two, leading to two bearing seats. Focusing on this splitting region, a cube-shaped volume containing the original bifurcation point is extracted as the topology optimization design domain.

[0031] In the Altair HyperWorks platform, the OptiStruct module was used for fluid topology optimization. The design variable was defined as the "pseudo-density" of each element within the design domain. The optimization objective was set to minimize the weighted sum of the total pressure drops at the two outlets after the split, under the same inlet flow rate (80 L / min). Constraints included a maximum material volume fraction of 35% (i.e., the final solid material must occupy at most 35% of the design domain) and a minimum member size of 2 mm (to ensure structural strength). After iterative calculations, the software output the optimal material distribution map. The results showed that the optimal structure was not a simple "Y"-shaped bifurcation, but rather formed a streamlined "split island" before the bifurcation. This island had a rounded head and gradually narrowed tail, guiding the fluid to separate smoothly and effectively avoiding common "dead zones" and vortices.

[0032] S4. Model Integration and Final Validation Based on the topology optimization results, the designers meticulously reconstructed the smooth surface of the distribution island in CAD software, and performed Boolean operations and filleting on it with the global "S"-shaped main oil passage model obtained in step 2 to form a seamlessly connected overall oil passage model.

[0033] The final model was imported into ANSYS Fluent for high-precision CFD verification. The simulation results were compared to ensure that, under the same operating conditions, the overall pressure drop of the optimized oil passage was lower than that of the original right-angled bifurcation oil passage, meeting the expected target. The original model exhibited a large area of ​​low-velocity vortex region after the bifurcation, while the optimized model showed a uniform velocity distribution and only extremely weak vortices after the bifurcation island. Flow noise assessment indicators also showed a significant improvement.

[0034] S5, Additive Manufacturing Realization The final 3D model was exported as an STL file and imported into the slicing software of an LPBF device (such as the EOS M290). Software analysis confirmed that the overhang angles of all internal surfaces of the oil passages were greater than 45°, and the system did not generate any internal supports. Only a small number of external grid-like supports were generated for the necessary areas where the bottom of the model contacts the substrate. 18Ni300 maraging steel powder was selected as the printing material. After printing, the model was removed from the substrate by wire cutting, the external supports were removed, and then sandblasted. The interior of the oil passages was inspected using an industrial endoscope to confirm that the inner walls were smooth, there were no support residues, and there were no defects visible to the naked eye.

[0035] The oil passage manufactured through the above process is a seamless metal component. It lacks threaded holes and plugs, and its internal flow channel is a complex, smoothly transitioning spatial surface. The guide island structure at its branch point is a unique design that cannot be achieved using traditional machining methods. This oil passage was integrated into the remanufacturing of the transmission box. Bench tests verified that its lubrication flow distribution is uniform, and the system temperature rise has decreased, achieving the expected goals of improving reliability and efficiency.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0038] For those skilled in the art, various changes and modifications will undoubtedly be apparent after reading the above description. Therefore, the appended claims should be construed as covering all changes and modifications that encompass the true intent and scope of the invention. Any and all equivalent scope and content within the scope of the claims should be considered to remain within the intent and scope of the invention.

Claims

1. A method for optimizing oil passage design based on additive manufacturing, characterized in that, Includes the following steps: S1. Feature Recognition: Obtain the original three-dimensional model of the oil channel to be optimized, identify the process holes, blind holes and flow channel inlets and outlets in the model, and identify the area to be optimized in the flow channel based on the preset additive manufacturing printing direction; S2. Path optimization and manufacturability design: After removing process holes and blind holes in the crude oil duct, the oil duct path of the region to be optimized is reconstructed based on a quasi-uniform B-spline curve. Adjust the curve parameters to make the reconstructed path meet the overhang angle constraints of additive manufacturing, and optimize the shape of the curve to obtain an optimized path with the goal of reducing flow resistance. S3. Local oil passage topology optimization: Extract the design domain in the critical flow region of the optimization path, use the actual working conditions as boundary conditions, the volume of material in the flow domain as constraint conditions, and the minimum fluid pressure drop in the design domain as the optimization objective to perform topology optimization and obtain the local configuration with optimized material distribution. S4. Model Reconstruction and Performance Verification: The local configuration is reconstructed into a geometric model and integrated with the optimization path to form a complete optimized oil passage model, which is then verified by fluid simulation. S5. Integrated Additive Manufacturing: The optimized oil passage model that has passed verification is given an outer diameter allowance and external support, and is integrally formed using metal additive manufacturing technology. The resulting oil passage has no internal support structure.

2. The method according to claim 1, characterized in that, In step S1, the region to be optimized is the flow channel region where the overhang angle is less than the first preset threshold and the aperture is greater than the second preset threshold.

3. The method according to claim 2, characterized in that, The first preset threshold is 40°, and the second preset threshold is 10mm.

4. The method according to claim 1, characterized in that, In step S2, the quasi-uniform B-spline curve is a fourth-order or higher curve; the shape optimization uses the control point coordinates of the curve as the design variable, the overhang angle constraint as the geometric constraint, and the minimum total pressure drop of the flow channel as the optimization objective, and is completed through fluid simulation analysis iteration; wherein, the overhang angle of the oil channel is greater than 40°.

5. The method according to claim 4, characterized in that, In step S2, the following algorithm is used for path optimization: Path representation: , , Where C(u) is a parametric curve defined by a B-spline, and u is a variable at any point on the path curve; N i,p (μ) is a basis function used to pass through control point P. i Fit a continuous path, where P0 is the starting point of the path, P n The endpoint of the path; Path constraints: Where Z'(u) is the rate of change of the curve in the Z direction at u, and D(C(u)) is the aperture function along the path; Objective function: ;in, J(P) is the objective function, representing the pressure loss under the design path; W1 is the weighting coefficient of the path length, i.e., the pressure loss along the path; and W2 is the weighting coefficient of the local pressure loss caused by the change of the path.

6. The method according to claim 1, characterized in that, In step S4, the reconstruction is based on the material density cloud map generated by topology optimization, and through isosurface extraction and geometric smoothing, a local flow channel structure with a machinable surface is generated.

7. An oil passage for a transmission device, characterized in that, The oil passage is manufactured by the oil passage optimization design method based on additive manufacturing as described in any one of claims 1 to 6.

8. The oil passage according to claim 7, characterized in that, The oil passage is a one-piece molded metal component with no internal process holes or sealing plugs, and the overhang angle of all internal flow channel surfaces is greater than 40°.

9. The oil passage according to claim 7 or 8, characterized in that, The oil passage contains a flow guiding structure generated by topology optimization design at the points where the flow direction changes or the cross-section changes.

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