A hydraulic valve block topology optimization method for a support-free printing flow channel and a hydraulic valve block

Abstract

The present application belongs to the technical field of hydraulic valve block preparation, and provides a hydraulic valve block topology optimization method for printing flow channels without support and a hydraulic valve block. Firstly, pressure loss is taken as a fluid dynamics optimization target to perform first topology optimization, and flow channel axes are determined. Then, second topology optimization is performed according to manufacturing feasibility, and flow channel cross-section parameters and shapes are determined. Finally, third topology optimization is performed with structural strength and function as optimization targets, redundant entities of the valve block are reconstructed, and a final topology-optimized hydraulic valve block entity model is obtained. Through optimization of the flow channel axes and the flow channel cross-section parameters and shapes, the flow channel is replaced by a straight hole formed in a mutually orthogonal or a certain angle manner. With pressure loss and manufacturing feasibility as targets, the valve block wall thickness requirement is guaranteed, and the redundant entities of the valve block are reconstructed with structural strength and function as targets, thereby solving the problems of heaviness caused by the reserved safety wall thickness and a large number of redundant entities not effectively utilized in the internal part.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydraulic valve block preparation, and particularly relates to a hydraulic valve block topology optimization method for printing flow channels without support. BACKGROUND

[0002] Traditional valve blocks are generally manufactured by casting or machining processes, and the materials are mainly cast iron and aluminum alloy. The internal flow channels of the valve blocks are usually vertical intersecting right-angle channel structures. This design is limited by manufacturing process constraints, resulting in inherent defects in flow channel layout. In recent years, topology optimization and additive manufacturing technology provide a new way for complex flow channel forming. The process characteristics theoretically support the overall manufacturing of arbitrary three-dimensional flow channel structures. However, existing topology optimization algorithms are mostly based on single field optimization, which cannot accurately represent the multi-physical field coupling effect of the hydraulic valve block under actual working conditions, and cannot fully utilize the geometric freedom advantage of additive manufacturing.

[0003] Although the traditional design method achieves the goals of reducing pressure loss and lightweight gain, it does not introduce relevant strategies at the beginning of topology optimization iteration, and does not fully utilize the lightweight potential of topology. Specifically, the traditional design method needs to compromise the flow channel shape under the limitation of drilling process. The flow channel can only be composed of mutually orthogonal or angled straight holes, and forms unavoidable right-angle turns or T-shaped intersections at the spatial intersection, resulting in large pressure loss and low efficiency. At the same time, in order to ensure that the drill bit does not penetrate adjacent flow channels or the outer wall of the valve block during drilling, the traditional design must reserve a thick safety wall thickness, so the valve block is usually designed as a heavy cuboid or a large-size solid body, and there are a large number of redundant entities inside the valve block that are not effectively utilized. In the face of complex and large-angle flow channels, supports need to be added to ensure the forming precision and surface quality, which restricts the application of additive manufacturing in the hydraulic field. SUMMARY

[0004] In order to solve the above problems, the application provides a hydraulic valve block topology optimization method for printing flow channels without support and a hydraulic valve block. The application optimizes the flow channel axis, flow channel cross-sectional parameters and shape, replaces the method that the flow channel can only be composed of mutually orthogonal or angled straight holes, guarantees the valve block wall thickness requirement by taking pressure loss and manufacturing feasibility as the target, and reconstructs the redundant entities of the valve block according to the structural strength and functional target, solves the problem of heaviness caused by reserving safety wall thickness, and solves the problem of a large number of redundant entities inside the valve block that are not effectively utilized.

[0005] In order to achieve the above purpose, the application is implemented by the following technical scheme:

[0006] In a first aspect, the application provides a hydraulic valve block topology optimization method for printing flow channels without support, comprising:

[0007] Obtaining initial valve block geometric features; discretely processing the initial valve block geometric features to determine the relative positions between relevant physical features;

[0008] Extracting all flow channel axes from the relevant physical features, performing first topology optimization with pressure loss as the fluid dynamics optimization target to determine the flow channel axes;

[0009] Taking the flow channel axes after the first topology optimization as the sweeping path, performing second topology optimization according to the manufacturing feasibility to determine the flow channel cross-sectional parameters and shapes;

[0010] According to the hydraulic valve block load spectrum, performing third topology optimization with structural strength and function as the optimization targets to reconstruct the valve block redundant entities and obtain the final topology-optimized hydraulic valve block entity model.

[0011] Further, the relevant physical features include valve block flow channels, valve seat holes, process holes, mounting holes, and redundant entity structures.

[0012] Further, the first topology optimization includes: designing the flow channel axes as gentle cubic B-spline curves; and adopting a gradient descent optimization method to adjust the curve coordinates with the minimization of the along-path pressure loss as the target.

[0013] Further, after the first topology optimization is completed, the minimum Euclidean distance of the spatial relative positions of the flow channel axes is calculated, and if the minimum Euclidean distance of any position is greater than a preset safety margin, the second topology optimization is entered, otherwise the first topology optimization is continued.

[0014] Further, the second topology optimization includes: determining the printing overhang angle according to the included angle between the printing direction and the flow channel axis; and adopting a circular shape for the flow channel cross section at the overhang angle < 45° and a water droplet shape for the flow channel cross section at the overhang angle of 90°.

[0015] Further, a plurality of holes with an inner diameter smaller than a preset value are arranged in parallel at the redundant entities of the optimized flow channel inner wall.

[0016] Further, after the second topology optimization is completed, it is judged whether the minimum wall thickness between the flow channels is greater than a preset value, and if so, the third topology optimization is entered, otherwise the first topology optimization and the second topology optimization are continued.

[0017] Further, the third topology optimization includes: setting the valve block flow channels, valve seat holes, and mounting holes as non-changeable non-design regions, and the remaining valve block redundant entities as topologically-optimizable design regions to establish a valve block three-dimensional entity finite element model; and according to the attribute parameters of the valve body material, iteratively calculating the valve block redundant entities by setting the constraint condition of maximum anisotropic material stiffness.

[0018] Further, after the third topology optimization is completed, the system maximum working pressure, bolt pre-tightening load and external vibration excitation working condition combination are simulated according to the valve block working load spectrum, functional test is carried out through structural mechanics simulation and interference check to determine whether the valve block meets the use requirement, if yes, the optimization is completed, otherwise, the valve block entity structure is re-topologically optimized.

[0019] In a second aspect, the application further provides a hydraulic valve block without support printing flow channel, which is obtained by the hydraulic valve block topology optimization method without support printing flow channel as described in the first aspect.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] 1. The application firstly performs the first topology optimization with pressure loss as the fluid dynamics optimization target to determine the flow channel axis, then performs the second topology optimization according to the manufacturing feasibility to determine the flow channel cross-section parameters and shape, and finally performs the third topology optimization with structural strength and function as the optimization target to reconstruct the valve block redundant entity and obtain the final hydraulic valve block entity model after topology optimization; through the optimization of the flow channel axis and the flow channel cross-section parameters and shape, the flow channel is replaced by the straight hole with mutual orthogonality or a certain angle, the valve block wall thickness requirement is guaranteed by taking the pressure loss and manufacturing feasibility as the target, the valve block redundant entity is reconstructed by taking the structural strength and function as the target, and the problem of bulkiness caused by the reserved safety wall thickness is solved, and the problem of a large number of redundant entities in the valve block that are not effectively utilized is solved.

[0022] 2. The application reconstructs the flow channel axis, cross-section shape and valve block redundant entity in sequence, determines the optimization target function through multi-physical field coupling simulation, and systematically realizes the step-by-step progressive optimization of the high-performance hydraulic valve block flow stability, structural stiffness and additive forming property.

[0023] 3. The traditional technology simply uses diameter as the threshold value of whether to optimize, which can change the cross-section shape of part of unnecessary optimized flow channels; based on this, the application introduces the overhang angle to determine whether to use the water drop type flow channel in addition to the diameter, which can reduce the decline of fluid dynamics characteristics caused by the reduction of flow area after printing. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings constituting a part of this embodiment are used to provide further understanding of the embodiment, and the schematic embodiment and its description are used to explain the embodiment, and do not constitute improper limitation on the embodiment.

[0025] Figure 1 It is a hydraulic valve block topology optimization flowchart of the embodiment of the application;

[0026] Figure 2A hydraulic valve block topology optimization flowchart for the embodiment 1 of the present application is shown in FIG. 1.

[0027] Figure 3 A flow channel axis diagram for the embodiment 1 of the present application is shown in FIG. 2.

[0028] Figure 4 A flow channel diagram after the first time of topology optimization for the embodiment 1 of the present application is shown in FIG. 3.

[0029] Figure 5 A hydraulic valve block flow channel cross-section diagram for the embodiment 1 of the present application is shown in FIG. 4, wherein (a) is a circular flow channel cross-section diagram, and (b) is a water drop flow channel cross-section diagram.

[0030] Figure 6 A valve block structure diagram after the third time of topology optimization for the embodiment 1 of the present application is shown in FIG. 5.

[0031] Wherein, 1, first valve seat hole; 2, second valve seat hole; 3, third valve seat hole; 4, fourth valve seat hole; 5, fifth valve seat hole; 6, first process hole; 7, second process hole; 8, third process hole; 9, first flow channel; 10, second flow channel; 11, third flow channel; 12, fourth flow channel; 13, circular flow channel cross-section; 14, water drop flow channel cross-section. DETAILED DESCRIPTION

[0032] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0034] As the core control unit of a hydraulic system, a hydraulic valve block bears the key functions of flow channel distribution, pressure regulation, and direction control. Traditional valve blocks are generally manufactured using casting or machining processes, with cast iron or aluminum alloy as the main material, and the internal flow channels are usually vertical intersecting right-angle channel structures. This design is limited by manufacturing process constraints, resulting in the following inherent defects in flow channel layout: right-angle bending causes turbulent flow effects, resulting in significant pressure loss; redundant material accumulation leads to excessive valve block volume; multi-body assembly brings about sealing interface leakage risks. With the development of hydraulic systems towards high pressure and integration, traditional structures have been difficult to meet the needs of compact space layout and high energy efficiency.

[0035] In recent years, topology optimization and additive manufacturing technology have provided a new way for complex flow channel forming, and its process characteristics theoretically support the overall manufacturing of arbitrary three-dimensional flow channel structures. However, existing topology optimization algorithms are mostly based on single field optimization, which is difficult to accurately represent the multi-physical field coupling effects under actual working conditions of hydraulic valve blocks, and therefore cannot fully utilize the geometric freedom advantages of additive manufacturing.

[0036] Hydraulic valve block as the key basic components of integrated control elements in hydraulic system, its performance directly affects the efficiency, reliability and space layout of the system. As described in the background art, the traditional design method needs to set the flow channel shape under the limitation of drilling process, the flow channel can only be composed of straight holes which are orthogonal or at a certain angle to each other, and straight turns or T-shaped intersections are formed at the spatial intersection, resulting in large pressure loss and low efficiency. At the same time, in order to ensure that the drill bit does not penetrate the adjacent flow channel or the outer wall of the valve block during drilling, the traditional design must reserve a thick safety wall thickness, so the valve block is usually designed as a heavy cube or a large size solid body, and there is a large amount of redundant entity inside which is not effectively utilized. The lightweight design method for hydraulic valve block has not formed a systematic structure optimization means, and for complex and large angle flow channels, support needs to be added to ensure the forming precision and surface quality, which restricts the application of additive manufacturing in the hydraulic field.

[0037] Based on this, in order to solve the inherent defects of traditional hydraulic valve block in fluid performance, structural efficiency, lightweight, manufacturing complexity and adaptability, etc., as shown in Figure 1 , a hydraulic valve block topology optimization method without support printing flow channel is provided, which adopts a three-stage topology optimization method, and through the collaborative design strategy of fluid dynamics optimization, manufacturing constraint driving and structure performance reconstruction, the optimal design method of hydraulic valve block is obtained.

[0038] The method performs step-by-step topology optimization with hydraulic valve block function and additive manufacturing process as constraints, and reconstructs the flow channel axis, cross-sectional shape and valve block redundant entity in sequence, determines the optimization objective function through multi-physical field coupling simulation, and systematically realizes the progressive optimization of high-performance hydraulic valve block flow stability, structural stiffness and additive forming property. The method comprises the following steps:

[0039] S1, the load spectrum of the hydraulic valve block is determined, the initial valve block geometric model is input, the initial valve block geometric characteristics are discretely processed, and the relative positions between the valve block flow channel, valve seat hole, process hole, mounting hole and redundant entity structure and other related physical characteristics are determined.

[0040] S2, all flow channel axes are extracted separately, and the first topology optimization is performed with pressure loss as the fluid dynamics optimization target to determine the flow channel axis.

[0041] Topology optimization is performed on the flow channel of the hydraulic valve block. The flow channel on the hydraulic valve block can be divided into two categories. The first category is a functional flow channel connecting the valve seat hole port. The other category is a process flow channel passing through the functional flow channel. In order to ensure that the position of the control valve mounting port is not changed after the hydraulic valve block is optimized, the valve block is installed in the same way as the initial valve block. According to the discretized geometric characteristics of the valve block, the relative position of the valve seat hole and the valve block flow channel space is determined and is not changed. Only the functional flow channel connecting the valve seat hole port is subjected to topology optimization. The process hole on the valve block for passing through the flow channel and the corresponding process flow channel are removed to prevent the generation of redundant entity features.

[0042] The first topology optimization retains the valve seat hole and the valve block flow channel, and the relative position of the valve seat hole space is not changed. The flow channel axis is optimized according to the objective function. After each optimization is completed, flow channel entity intersection checking is performed to ensure that there is no intersection interference before entering the next step.

[0043] In some embodiments, by establishing the fluid-structure coupling dynamics equation of the flow channel, the dynamic evolution of the flow channel axis is realized by solving the extremum of the equation. Compared with the experience formula regression method and other pure data-driven methods, it has mathematical guarantee for the continuity of the physical field.

[0044] S2.1, the topology optimization of the valve block flow channel is divided into optimization of the flow channel axis and optimization of the flow channel section. The flow channel axis is the main guiding structure of fluid flow, and its geometric form directly affects key fluid mechanics parameters such as flow separation, pressure loss and turbulence intensity. Optionally, the curvature of the axis can be optimized by parameterizing a cubic B-spline curve to realize the gradual change of the curvature radius. In the optimization process, a pressure loss objective function is established, a gradient descent optimization method is used, and the curve coordinates are adjusted to minimize the pressure loss along the way. The optimization iteration is completed by the fluid simulation software. By topology optimization of the flow channel axis, the right-angle turn or T-shaped intersection formed by the traditional manufacturing process can be avoided, and the generation of intense turbulence, vortex and flow separation of fluid at the corner can be prevented, thereby improving the system efficiency.

[0045] Optionally, the flow channel axis is constructed by parameterizing a cubic B-spline curve. Based on the physical constraints of curvature continuity and minimum turning radius, the fluid velocity gradient field is extracted by the Navier-Stokes equation to modify the curvature of the cubic B-spline curve. The control points of the cubic B-spline are iteratively optimized by the gradient descent method to ensure that the curvature change rate meets the manufacturing requirements. Compared with conventional techniques, the local shape approximation is used to replace the static spline curve in the present embodiment, which can solve the multi-objective optimization problem of collaborative optimization of flow channel flow performance and manufacturing feasibility.

[0046] The pressure loss function of the present embodiment is based on the fluid-structure coupling dynamics equation, which can realize the pressure loss gradient of the flow field, and react on the solid domain to drive the flow channel shape to evolve in the direction of low resistance.

[0047] ;

[0048] wherein, is a pressure loss objective function, is a fluid dynamic viscosity, is a velocity gradient tensor, is a fluid domain volume, is a flow passage pressure difference, is a fluid domain boundary.

[0049] The flow passage axis is designed as a gentle cubic B-spline curve, and the main optimization objective of the flow passage axis is to minimize the pressure loss along the passage, and the flow passage pressure loss is analyzed by fluid simulation software or method.

[0050] S2.2, after the topology of the flow passage axis is completed, the spatial intersection detection of the axis is required to be performed by a geometric interference verification mechanism, a safety margin is determined based on the original valve block flow passage diameter, the minimum Euclidean distance of the spatial relative position of the flow passage axis is calculated, and if the minimum Euclidean distance at any position is greater than the safety margin, step S3 can be entered, otherwise the flow passage axis is re-topologically optimized in step S2.

[0051] S3, the first topologically optimized flow passage axis is taken as a sweeping path, and the second topological optimization is performed according to the manufacturing feasibility to determine the flow passage cross-sectional parameters and shapes.

[0052] S3.1, before the second topological optimization, the printing direction of the valve block needs to be determined first, the printing overhang angle is determined according to the included angle between the printing direction and the flow passage axis, the flow passage cross section at the overhang angle < 45° is circular, the flow passage cross section at the overhang angle of 90° is drop-shaped, and the overhang angle < 45° is taken as the objective function for optimization in the transition region, and a small parallel hole is set at the redundant entity of the optimized flow passage inner wall to prevent the cross section from being reduced and the weight from being increased.

[0053] Specifically, after the topology optimization of the flow passage axis is completed, the flow passage cross section is topologically optimized according to the manufacturing requirements. Before the cross section optimization, the printing direction of the valve block needs to be determined first, the flow passage axis is discretely sampled along the parameters, the included angle between the tangent direction of each point axis and the printing direction is calculated, and the flow passage cross section is classified and processed according to the included angle value. Among them, the overhang angle < 45° is divided into the bottom overhang area, the flow passage cross section does not change, and the circular cross section of the initial flow passage is adopted; the overhang angle of 90° is divided into the high overhang area, in order to prevent collapse during printing, a drop-shaped cross section is adopted as Figure 5The water droplet type cross section shown; the overhanging angle is between 45° and 90°, which is divided into a transition zone, in order to ensure the continuity of the cross section position, the continuity of the section, and the continuity of the curvature, combined with the lofting algorithm of the curved surface, the transition surface fitting is carried out with the cross section curve and the printing direction <45° as the objective function. At the same time, in order to prevent the increase of flow velocity caused by the reduction of flow passage cross section, and the increase of redundant entities in the flow passage after optimization, reduce the influence of flow passage cross section optimization on the performance of the valve block, set a small hole in parallel at the redundant entity of the inner wall of the optimized flow passage, the inner diameter of the hole <8mm, ensure that the hole can be printed without support.

[0054] It should be noted that in the conventional technology, the diameter is used to determine whether to use the water droplet type flow passage, and any overhanging angle can be printed for the flow passage with a diameter less than 8mm, but the flow passage with an overhanging angle <45° can be successfully printed even if the diameter is greater than 8mm without changing the cross section shape, so simply using the diameter as the threshold value of optimization will change the cross section shape of part of the unnecessary optimization flow passage. Based on this, in addition to the diameter, the overhanging angle is introduced to determine whether to use the water droplet type flow passage, which can reduce the decline of fluid dynamics caused by the reduction of cross-sectional area after printing.

[0055] S3.2, after the topology optimization of the flow passage cross section is completed, the minimum wall thickness of the flow passage needs to be checked to ensure that the wall thickness of the flow passage is not less than the preset value, which can meet the working pressure demand before entering the next step.

[0056] Specifically, in order to prevent the hydraulic valve block from being broken in use, after the flow passage cross section fitting is completed, the distance between the flow passage fitting surfaces should be detected according to the hydraulic valve block load spectrum, and the minimum wall thickness value between the flow passages is generally not less than 5mm, and can be multiplied by the corresponding safety factor according to the highest working pressure in the flow passage. If the distance between all flow passage fitting surfaces is greater than the safety wall thickness, it can enter step S4, otherwise it returns to step S2 and step S3 to re-optimize the flow passage axis and flow passage cross section.

[0057] S4, according to the hydraulic valve block load spectrum, the third topology optimization is carried out according to the optimization target of structural strength and function, and the redundant entity of the valve block is reconstructed to obtain the final topology optimized hydraulic valve block entity model.

[0058] S4.1, the third topology optimization reconstructs the redundant entity according to the function constraint and manufacturing constraint of the hydraulic valve block, and the entity surface adopts smooth cambered surface to reduce the existence of stress concentration structure.

[0059] Specifically, the completed flow channel, valve seat hole and mounting hole are set as non-changeable non-design area, and the remaining valve block redundant entity is set as design domain for topology optimization. A three-dimensional entity finite element model of the valve block is established, and the elastic modulus, Poisson's ratio, yield strength and other attribute parameters of the valve body material are input. Iterative calculation is performed on the redundant entity of the valve block by setting the constraint condition of maximum stiffness of anisotropic material. When the structural stress concentration coefficient is lower than the safety value, the iteration is stopped and the optimization result is output. In the optimization process, a smooth transition of the special-shaped structure is generated through surface fitting technology, and the topology features of the reinforcing ribs added to the pressure-bearing wall are highlighted, and the arc-shaped transition structure for stress dispersion is constructed in the cross-hole area to prevent stress concentration.

[0060] When the stress concentration of the valve block is greater than the preset safety value, the third topology optimization is performed again. It should be noted that when the third topology optimization is returned, if only the position where the stress concentration is greater than the preset safety value is optimized, the stress of other positions may increase. At this time, the important positions are optimized and limited:

[0061] When the stress concentration at the connection between the first flow channel 9, the second flow channel 10, the third flow channel 11 or the fourth flow channel 12 and the first valve seat hole 1 is greater than the preset safety value, at this time, in order not to affect the overall fluid performance, only the connection is reinforced, such as increasing the welding point outside or increasing the external wall thickness of the flow channel connection. If the stress concentration is lower than the safety value after reinforcement, the optimization result is iterated and output; otherwise, continue to optimize. If the optimization times exceed the preset number of times, it means that the reinforcement method cannot meet the requirements, and the orientation, wall thickness, etc. of the first flow channel 9, the second flow channel 10, the third flow channel 11 or the fourth flow channel 12 are considered for optimization until the stress concentration after reinforcement is lower than the safety value.

[0062] When the stress concentration at the connection between the first flow channel 9, the second flow channel 10, the third flow channel 11 or the fourth flow channel 12 and the first valve seat hole 1 is greater than the preset safety value, at this time, in order not to affect the overall fluid performance, only the connection is reinforced, such as increasing the welding point outside or increasing the external wall thickness of the flow channel connection. If the stress concentration is lower than the safety value after reinforcement, the optimization result is iterated and output; otherwise, continue to optimize. If the optimization times exceed the preset number of times, it means that the reinforcement method cannot meet the requirements, and the orientation, wall thickness, etc. of the first flow channel 9, the second flow channel 10, the third flow channel 11 or the fourth flow channel 12 are considered for optimization until the stress concentration after reinforcement is lower than the safety value.

[0063] If the stress concentration is lower than the safety value after optimization, the optimization result is iterated and output; otherwise, continue to optimize. If the optimization times exceed the preset number of times, it means that the wall thickness optimization method cannot meet the requirements, and the orientation of the corresponding flow channel is optimized until the stress concentration after reinforcement is lower than the safety value.

[0064] S4.2, After the topology optimization of the redundant entity is completed, mechanical simulation analysis and function checking are performed on the hydraulic valve block load spectrum to ensure that the optimized valve block can meet the use requirements before entering the next step.

[0065] Specifically, after the hydraulic valve block optimization in step S4 is completed, the system maximum working pressure, bolt pre-tightening load, external vibration excitation and other typical working condition combinations are simulated according to the valve block working load spectrum, functional testing is performed through structural mechanics simulation and interference checking, and it is determined that the valve block can meet the use requirements. If the testing is not passed, the entity structure of the valve block is re-optimized in step S4.

[0066] S5, according to the hydraulic valve block entity model, laser powder bed fusion technology is used to complete printing preparation.

[0067] Optionally, before the hydraulic valve block entity model is prepared, the printing parameters are determined according to the hydraulic valve block material, and the support and slicing processing are sequentially added, and finally the laser powder bed fusion technology is used for preparation.

[0068] Specifically, after the functional testing in step S4 is met, the valve block entity is prepared by using the laser powder bed fusion technology in step S5. Before printing, the printing parameters are determined according to experience, and the support is sequentially added to the external entity structure with a cant angle greater than 45°, and the valve block entity model after adding the support is sliced.

[0069] The application also provides a hydraulic valve block with a support-free printing flow channel, which is obtained by the support-free printing flow channel hydraulic valve block topology optimization method.

[0070] The application optimizes the flow channel axis form, cross-sectional shape and redundant entity structure in sequence through multi-target and multi-step cooperative optimization, effectively reduces the pressure loss and mass of the valve block along the way, and ensures the self-supporting manufacturability and pressure-bearing reliability of the flow channel. This progressive and target-oriented optimization strategy eliminates the dilemma that fluid, manufacturing and structural targets cannot be completely unified in traditional valve block design, and realizes the optimal solution of overall performance.

[0071] The application is driven by the optimization of three physical targets of fluid performance, manufacturing constraints and structural strength, and finally outputs an entity model directly used for laser powder bed fusion (LPBF) equipment. Combined with fluid simulation, mechanical simulation and constraint checking, the high-quality conversion from model to entity is ensured.

[0072] Embodiment 1

[0073] The embodiment provides a support-free printing flow channel hydraulic valve block topology optimization method, which takes a specific example of a hydraulic valve block design and manufacturing method to illustrate.

[0074] As Figure 2As shown, a hydraulic valve block designed and manufactured using traditional machining methods includes a first valve seat hole 1, a second valve seat hole 2, a third valve seat hole 3, a fourth valve seat hole 4, a fifth valve seat hole 5, a first process hole 6, a second process hole 7, and a third process hole 8. The valve seat holes are used to install the control valve, and the process holes are machining holes remaining on the valve block surface after machining the process flow channels; they are generally plugged using plugs. The optimization and manufacturing method of the hydraulic valve block in this embodiment includes:

[0075] S1. Define the load spectrum of the hydraulic valve block and the typical working conditions of the valve block. Discretize the valve block features and define the relative spatial positions between the valve block features.

[0076] S2, such as Figure 3 As shown, the valve seat hole and process hole features are preserved, the flow channel axis is extracted, and the location and quantity of right-angle flow channels and T-shaped flow channels are analyzed.

[0077] Remove the process holes and corresponding flow channels, connect each valve seat port through a cubic B-spline curve according to the through relationship, and perform topology optimization on the flow channel axis to minimize pressure loss.

[0078] After the flow channel axis is optimized, the overall layout is as follows: Figure 4 As shown, the middle port of the first valve seat hole 1 is connected to the bottom ports of the second valve seat hole 2, the third valve seat hole 3 and the fourth valve seat hole 4 respectively to form the third flow channel 11, the fourth flow channel 12 and the first flow channel 9; the bottom port of the first valve seat hole 1 and the bottom port of the fifth valve seat hole 5 are connected to form the second flow channel 10.

[0079] Using the original valve block diameter as a safety margin, the spatial intersectingity of the first flow channel 9, the second flow channel 10, the third flow channel 11, and the fourth flow channel 12 is tested. The distance between flow channels that do not enter the same valve seat port should be less than the safety margin; otherwise, the flow channel axis is re-optimized.

[0080] Output the optimized flow channel axis features.

[0081] S3. Calculate the diameter of the flow channel cross-section. For flow channels with a diameter < 8mm, no support is needed for printing; step S3 can be skipped, and all steps can proceed as follows. Figure 5 The circular flow channel section 13 shown in the figure; for flow channels with a diameter ≥ 8 mm, flow channel section topology optimization is still required to achieve supportless printing.

[0082] The 3D printing direction is determined to be the axis direction of the first valve seat hole 1, and the angle between the axis of each flow channel after optimization and the printing direction is calculated as the overhang angle.

[0083] The optimization targets are divided according to the overhang angle value, and the axial region with an overhang angle < 45° is used as follows: Figure 5The circular flow passage section 13 is shown; the axis region with a 90° overhang angle uses the method as Figure 5 The water droplet flow passage section 14 is shown; the water droplet-shaped section upper side straight line and the printing direction angle needs to be less than 45°; the middle region is a transition region, combined with the curve lofting algorithm, the transition surface fitting is carried out with the section curve and the printing direction < 45° as the objective function. At the same time, the flow passage of the water droplet flow passage section 14 is provided with a circular hole with a diameter < 8mm, which forms a parallel hole with the water droplet hole, reducing the influence of flow passage section optimization on the performance of the valve block.

[0084] According to the minimum wall thickness determined by the valve block use pressure, the distance between the obtained flow passage inner walls should be greater than the minimum wall thickness, otherwise the flow passage axis optimization is re-performed.

[0085] Output the optimized flow passage entity characteristics.

[0086] S4, set the valve seat hole obtained in step S1 and the flow passage obtained in step S3 as non-changeable non-design regions, and establish a parameterized three-dimensional model according to the actual size of the original valve block, and retain the redundant entities as design domains through Boolean operation.

[0087] Combine the valve block load spectrum, and input the elastic modulus, Poisson's ratio, yield strength and other attribute parameters of the valve body material.

[0088] Set the volume reduction target, and perform geometric reconstruction on the redundant entities with the maximum anisotropic stiffness as the constraint condition. For the wall surface bearing pulsating pressure, arrange reinforcing ribs along the principal stress trace, and adopt a double curvature transition structure in the cross-hole region to ensure the continuity of the surface curvature.

[0089] According to the valve block typical working condition in step S1, perform multi-physical field simulation on the topologically optimized valve block to ensure that the valve block can meet the use requirements, otherwise re-topologically optimize the redundant entities of the valve block.

[0090] Output the optimized valve block entity model.

[0091] S5, in order to ensure the assembly accuracy between the valve block and the remaining components, add machining allowance to the features with high machining precision requirements such as valve seat hole.

[0092] According to the printing direction determined in step S3, add supports to the convex parts, inclined surfaces and end surfaces of the valve block with an overhang angle > 45° on the outer surface, and select columnar or grid-shaped supports according to the position difference.

[0093] Divide the valve block entity model with added supports into a series of horizontal layers by slicing the model according to the set layer thickness.

[0094] Complete the preparation of the valve block by using laser powder bed fusion technology.

[0095] The valve block key feature processing and support removal are completed by a numerical control machine tool.

[0096] Figure 6 As shown, the topological optimization hydraulic valve block mechanism is obtained by manufacturing after optimization by the method of the embodiment, which maximizes the weight reduction of the hydraulic valve block, improves the lightweight level of the hydraulic valve block, reduces the flow passage pressure loss, and improves the flow efficiency.

[0097] The above only describes the preferred embodiments of the present embodiment and is not intended to limit the present embodiment. Those skilled in the art can make various modifications and changes to the present embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present embodiment shall be included in the protection scope of the present embodiment.

Claims

1. A topology optimization method for a hydraulic valve block of a support- free printing runner, characterized in that, The method comprises the following steps: acquiring initial valve block geometric features; discretizing the initial valve block geometric features to determine the relative positions between relevant physical features; the relevant physical features include valve block flow channels, valve seat holes, process holes, mounting holes, and redundant entity structures; extracting all flow channel axes from the relevant physical features, and performing first topology optimization on the flow channel axes to determine the flow channel axes, taking pressure loss as the fluid dynamics optimization target; the first topology optimization includes: designing the flow channel axes as gentle cubic B-spline curves, optimizing the curvature of the axes by parameterizing the cubic B-spline curves, and realizing the gradual change of the curvature radius; during the optimization process, a pressure loss objective function is established, and a gradient descent optimization method is adopted to adjust the curve coordinates to minimize the pressure loss along the way, and the optimization iteration under multiple working conditions is completed through a fluid simulation software; taking the flow channel axes after the first topology optimization as the sweeping path, and performing second topology optimization according to the manufacturing feasibility to determine the flow channel cross-sectional parameters and shapes; performing third topology optimization on the valve block redundant entity according to the valve block load spectrum, taking structural strength and function as the optimization targets, and obtaining the final topology-optimized hydraulic valve block entity model.

2. A topology optimization method of a hydraulic valve block without support printing flow channels as claimed in claim 1, characterized in that, After the first topology optimization is completed, the minimum Euclidean distance of the spatial relative positions of the flow channel axes is calculated, if the minimum Euclidean distance of any position is greater than a preset safety margin, the second topology optimization is entered, otherwise the first topology optimization is continued.

3. The topology optimization method of a hydraulic valve block without support printing flow channels according to claim 1, wherein, The second topology optimization includes: determining the printing overhang angle according to the included angle between the printing direction and the flow channel axis; the flow channel cross section at the overhang angle < 45° adopts a circular shape, and the flow channel cross section at the overhang angle of 90° adopts a water drop shape.

4. A topology optimization method of a hydraulic valve block without support printing flow channels as claimed in claim 3, characterized in that, A plurality of holes with an inner diameter smaller than a preset value are arranged in parallel at the redundant entity of the inner wall of the optimized flow channel.

5. A topology optimization method of a hydraulic valve block without support printing flow channels as claimed in claim 3, wherein, After the second topology optimization is completed, it is judged whether the minimum wall thickness between the flow channels is greater than a preset value, if yes, the third topology optimization is entered, otherwise the first topology optimization and the second topology optimization are continued.

6. A topology optimization method of a hydraulic valve block without support printing flow channels as claimed in claim 1, wherein, The third topology optimization includes: setting the valve block flow channels, valve seat holes, and mounting holes as non-designable non-design regions, and setting the remaining valve block redundant entities as designable design regions to establish a valve block three-dimensional entity finite element model; according to the attribute parameters of the valve body material, the valve block redundant entity is iteratively calculated by setting the constraint condition of maximum anisotropic material stiffness.

7. A topology optimization method of a hydraulic valve block without support printing flow channels as claimed in claim 6, characterized in that, After the third topology optimization is completed, the system maximum working pressure, bolt pre-tightening load, and external vibration excitation working condition combination are simulated according to the valve block working load spectrum, functional testing is performed through structural mechanics simulation and interference checking to determine whether the valve block meets the use requirements, if yes, the optimization is completed, otherwise the valve block entity structure is re-topologically optimized.

8. A hydraulic valve block without support printing flow channels, characterized in that, The hydraulic valve block is obtained by the topology optimization method of the unsupported printing flow channel according to any one of claims 1-7.

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