Additive manufacturing transverse hole formability high-throughput evaluation and optimization method

Abstract

The invention discloses an additive manufacturing transverse hole formability high-throughput evaluation and optimization method. The method comprises the following steps that a transverse hole high-throughput evaluation model is established; preparing an evaluation model by adopting the target process parameters; on the basis of formability of different apertures, determining a limit forming size, and establishing a high-throughput optimization model of a corresponding structure size for a transverse hole of which the aperture of an actual part is greater than the limit forming size; preparing an optimization model by adopting corresponding process parameters; and 5, optimizing the model structure based on the optimal formability. By means of the method, the transverse hole forming capacity of different materials and corresponding optimization targets can be efficiently screened, the feature structure model suitable for additive manufacturing is rapidly obtained under the condition that the minimum machining allowance and the optimal forming quality are guaranteed, and the optimization time is greatly shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of metal additive manufacturing, and in particular to a high-throughput evaluation and optimization method for the formability of lateral holes in additive manufacturing. Background Art

[0002] Additive manufacturing technology is to stack metal materials layer by layer into the required shape, which is conducive to the preparation of parts with complex shapes and liberates the freedom of design. However, in the preparation of actual parts, due to the influence of the placement of parts, there are usually forming features of transverse holes, and the aperture of the transverse hole will affect the formability of the area. Generally speaking, the larger the aperture, the worse the formability, resulting in the surface quality, dimensional accuracy, and organizational properties of the final parts not being able to fully meet the technical requirements. Therefore, it is usually necessary to improve the formability of transverse holes by optimizing the model. The limit forming dimensions of transverse holes under different materials and different process parameters are different. Therefore, the corresponding limit forming dimensions need to be obtained for each material and process parameter to assist model preprocessing and optimization. Discrete specimens are usually used to obtain the formability of characteristic structures at different sizes. This method requires a lot of model processing and analysis, and the required cycle is long. In addition, discrete specimens cannot analyze the formability of continuous sizes. If you want to improve the accuracy of the limit forming dimensions, you can only further increase the specimens, and the material and time costs are high. Summary of the invention

[0003] The main purpose of the present invention is to provide a high-throughput evaluation and optimization method for the formability of transverse holes in additive manufacturing, which can realize the rapid screening and optimization of the limit forming size of the transverse holes and improve the efficiency of model optimization.

[0004] To this end, the present invention provides a high-throughput evaluation and optimization method for additive manufacturing transverse hole formability, comprising the following steps: Step 1: Establish a high-throughput evaluation model for transverse pores with gradually changing pore diameters along the axial direction; Step 2: assign process parameters to the transverse hole high-throughput evaluation model, prepare additive manufacturing high-throughput samples, and analyze whether the forming quality of the high-throughput samples at different apertures meets the design technical requirements, and determine the limit forming aperture that meets the design technical requirements; Step 3: Compare the limit forming aperture with the transverse hole aperture of the actual part model to be printed. For transverse holes whose actual aperture to be printed is smaller than the limit forming aperture, directly use the actual part model to be printed for printing. For transverse holes whose actual aperture to be printed is larger than the limit forming aperture, go to step 4. Step 4: Based on the transverse aperture of the actual part model to be printed, a transverse hole high-throughput optimization model is established. The transverse hole cross-sectional contour lines at various locations in the transverse hole high-throughput optimization model are composed of a lower arc segment and an upper inverted V-shaped segment. The lower two ends of the inverted V-shaped segment are respectively connected to the two ends of the arc segment, and the upper end is located at the vertex position of the transverse hole before optimization. The radius of the arc segment is equal to the aperture of the transverse hole before optimization. The arc segment of each transverse hole cross-sectional contour line of the high-throughput optimization model intercepted along the axial direction gradually becomes longer, and the angle of the inverted V-shaped segment gradually becomes larger; Step 5. Assign the same process parameters as in step 2 to the high-throughput optimization model of the transverse hole, prepare the additive manufacturing high-throughput specimen, and analyze the forming quality of the inverted V-shaped segment at different cross-sections of the specimen to determine the maximum design angle allowed for the inverted V-shaped segment when the forming quality meets the design technical requirements. Use the transverse hole cross-sectional contour line corresponding to the inverted V-shaped segment as the transverse hole contour of the final component printing model for printing.

[0005] Specifically, the transverse hole high-throughput evaluation model is composed of a plurality of gradient segments, and the apertures of the plurality of gradient segments gradually decrease or increase along the axial direction of the transverse hole.

[0006] Specifically, the maximum and minimum transverse pore diameters to be evaluated are determined, and a transverse pore model with continuously changing pore diameters is established with these two diameters as boundaries. The transverse pore model is then divided into 10-20 gradient segments, with each gradient segment having an pore diameter change of 1-2 mm and each gradient segment spaced 0.5 mm apart, thereby establishing a transverse pore high-throughput evaluation model.

[0007] Specifically, the angle of the inverted V-shaped segment of the high-throughput optimization model is set to 90°-150°, and the top of the inverted V-shaped segment is rounded.

[0008] Specifically, the forming quality includes surface integrity, roughness, hardness and / or microstructure.

[0009] Compared with the prior art, the present invention has the following beneficial effects: The present invention takes the minimum machining allowance as the criterion and establishes a high-throughput evaluation model for transverse holes. The high-throughput evaluation model uses a high-throughput sample to quickly obtain the ultimate forming size of the transverse hole, and quickly screens the forming size and forming process that meet the technical conditions based on the technical requirements of the target parts, and determines the aperture range of direct forming. There is no need to obtain the required forming capacity by repeatedly refining the size structure as in discrete samples. The high-throughput optimization model can quickly screen the optimization scheme of the transverse hole model with the minimum machining allowance, greatly reducing the difficulty of post-processing, which is beneficial to improving the iterative efficiency of process and model optimization, and improving the quality and efficiency of the forming and post-processing processes of parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0011] Figure 1 This is a flow chart of the evaluation and optimization of the transverse hole formability of the present invention; Figure 2 Schematic diagram of the high-throughput evaluation model for lateral pores; Figure 3 Schematic diagram of the high-throughput optimization model for lateral pores. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] See also Figure 1 , a high-throughput evaluation and optimization method for additive manufacturing transverse hole formability, comprising the following steps: Step 1: Determine the maximum and minimum transverse apertures to be evaluated, and use these two apertures as boundaries to establish a transverse aperture model with continuously changing apertures. In order to reduce the mutual influence between the formability of different apertures, the transverse aperture model is divided into 10-20 gradient segments, and the aperture change of each gradient segment is 1-2mm (based on the maximum and minimum aperture difference), and the interval between each gradient segment is 0.5mm, so as to establish a high-throughput evaluation model for transverse apertures (such as Figure 2 ).

[0014] Step 2: Assign process parameters to the evaluation model, use the metal powder to be evaluated as raw material, prepare additive manufacturing high-throughput samples, and analyze whether the surface integrity, roughness, hardness, microstructure, etc. at different apertures meet the technical requirements, and determine the limit forming aperture that meets the technical requirements; Step 3: Compare the limit forming aperture with the actual transverse aperture of the part model to be printed. For transverse holes whose actual aperture to be printed is smaller than the limit forming aperture, no model processing is required and they can be formed directly. For transverse holes whose actual aperture to be punched is larger than the limit forming aperture, the next step of model optimization is required to obtain transverse holes with the minimum processing allowance. Step 4: Based on the actual lateral hole diameters in the model of the part to be printed, a lateral hole high-throughput optimization model is established, such as Figure 3As shown in the figure, the cross-sectional contour lines of the transverse holes at various locations in the transverse hole high-throughput optimization model are composed of a lower arc segment and an upper inverted V-shaped segment. The lower two ends of the inverted V-shaped segment are respectively connected to the two ends of the arc segment, and the upper end is located at the vertex of the transverse hole before optimization. The radius of the arc segment is equal to the aperture of the transverse hole before optimization (the aperture of the transverse hole of the actual component model to be printed). The arc segments of the cross-sectional contour lines of each transverse hole of the transverse hole high-throughput optimization model intercepted along the axial direction gradually become longer, and the angle of the inverted V-shaped segment gradually becomes larger.

[0015] Specifically, the optimized cross-sectional contour of the transverse hole is to replace the upper arc of the hole with a straight line to improve the formability of the large aperture. The two straight lines are arranged in an inverted V shape, thereby forming an inverted V-shaped segment. The top of the inverted V-shaped segment is the highest point of the arc, and the two ends of the bottom are respectively connected to the two ends of the lower arc and symmetrical about the center of the hole. In order to obtain the minimum machining allowance, a high-throughput optimization model for transverse holes is established. The angle of the inverted V-shaped segment of the model is set to 90°-150° (the larger the angle, the less the allowance), and a 0.5mm fillet is set at the top of the inverted V-shaped segment to avoid stress concentration there.

[0016] Step 5. Assign corresponding process parameters to the optimized model, use the metal powder to be optimized as raw material, prepare additive manufacturing high-throughput specimens, and analyze whether the surface integrity, roughness, hardness, microstructure, etc. at different inverted V-shaped segment angles meet the technical requirements, determine the maximum inverted V-shaped segment angle that meets the technical requirements, obtain the optimized transverse hole optimization scheme, replace the transverse hole scheme in the actual part model to be printed with the optimized transverse hole scheme, obtain the final part printing model, and print it.

[0017] The present invention takes the minimum machining allowance as the criterion and establishes a high-throughput evaluation and optimization model for transverse holes. The high-throughput evaluation model uses a high-throughput sample to quickly obtain the ultimate forming size of the transverse hole, and quickly screens the forming size and forming process that meet the technical conditions based on the technical requirements of the target component, and determines the aperture range of direct forming. There is no need to obtain the required forming capacity by repeatedly refining the dimensional structure as in the case of discrete samples. The high-throughput optimization model can quickly screen the optimization scheme of the transverse hole model with the minimum machining allowance, greatly reducing the difficulty of post-processing, which is beneficial to improving the iterative efficiency of process and model optimization, and improving the quality and efficiency of the forming and post-processing processes of components. Specific examples

[0018] like Figure 2 A transverse pore high-throughput evaluation model was established, with the pore size set to 1-20 mm, divided into 10 gradient segments, each with a 2 mm pore size change, and each gradient segment was separated by 0.5 mm.

[0019] The evaluation model was given process parameters, and GH4169 alloy powder was used as raw material. High-throughput samples were prepared using selective laser melting equipment, and three evaluation models were printed using three different scanning speeds. The laser power was 285W, the scanning speeds were 960, 1160, and 1360 mm / s, the scanning spacing was 0.1 mm, and the layer thickness was 0.04 mm.

[0020] The high-throughput sample was cut horizontally along the hole, and the surface quality was observed using a three-dimensional profilometer. The sample with a scanning speed of 1360 mm / s had poor fusion when the hole diameter was greater than 13.6 mm, and obvious gaps appeared at 18.1 mm; the sample with a scanning speed of 1160 mm / s began to have poor fusion when the hole diameter was greater than 11.2 mm, and obvious gaps appeared at 16.8 mm; the sample with a scanning speed of 960 mm / s began to have poor fusion when the hole diameter was greater than 8.9 mm, and obvious gaps appeared when the hole diameter was greater than 13.4 mm.

[0021] Since there are 20mm transverse holes in actual parts, they cannot be formed directly. Therefore, a transverse hole optimization model is established with a hole diameter of 20mm, and the process parameters are set consistent with the previous ones.

[0022] The formed parts were cut horizontally along the vertical holes, and the surface quality was observed using a three-dimensional profilometer. The sample with a scanning speed of 1360 mm / s had a complete formed surface when the straight edge angle was less than 143°; the sample with a scanning speed of 1160 mm / s had a complete formed surface when the straight edge angle was less than 120°; and the sample with a scanning speed of 960 mm / s had a complete formed surface when the straight edge angle was less than 105°.

[0023] Based on the above, the ultimate forming size of the transverse hole and the optimized structure of the difficult-to-form size of the GH4169 alloy at different scanning speeds can be obtained.

[0024] The above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A high-throughput evaluation and optimization method for additive manufacturing transverse hole formability, characterized in that: The steps include: Step 1: Establish a high-throughput evaluation model for transverse pores with gradually changing pore diameters along the axial direction; Step 2: assign process parameters to the transverse hole high-throughput evaluation model, prepare additive manufacturing high-throughput samples, and analyze whether the forming quality of the high-throughput samples at different apertures meets the design technical requirements, and determine the limit forming aperture that meets the design technical requirements; Step 3: Compare the limit forming aperture with the transverse hole aperture of the actual part model to be printed. For transverse holes whose actual aperture to be printed is smaller than the limit forming aperture, directly use the actual part model to be printed for printing. For transverse holes whose actual aperture to be printed is larger than the limit forming aperture, go to step 4. Step 4: Based on the aperture of the transverse holes of the actual model of the component to be printed, a high-throughput optimization model for transverse holes is established. The cross-sectional contour lines of the transverse holes at various locations in the high-throughput optimization model for transverse holes are composed of a lower arc segment and an upper inverted V-shaped segment. The lower two ends of the inverted V-shaped segment are respectively connected to the two ends of the arc segment, and the upper end is located at the vertex position of the transverse hole before optimization. The radius of the arc segment is equal to the aperture of the transverse hole before optimization. The arc segment of each transverse hole cross-sectional contour line of the high-throughput optimization model for transverse holes taken along the axial direction gradually becomes longer, and the angle of the inverted V-shaped segment gradually becomes larger. Step 5. Assign the same process parameters as in step 2 to the high-throughput optimization model of the transverse hole, prepare the additive manufacturing high-throughput specimen, and analyze the forming quality of the inverted V-shaped segment at different cross-sections of the specimen to determine the maximum design angle allowed for the inverted V-shaped segment when the forming quality meets the design technical requirements. Use the transverse hole cross-sectional contour line corresponding to the inverted V-shaped segment as the transverse hole contour of the final component printing model for printing.

2. The high-throughput evaluation and optimization method for additive manufacturing transverse hole formability according to claim 1, characterized in that: The transverse hole high-throughput evaluation model consists of a number of gradient segments, and the apertures of the gradient segments gradually decrease or increase along the axial direction of the transverse hole.

3. The high-throughput evaluation and optimization method for additive manufacturing transverse hole formability according to claim 2, characterized in that: Determine the maximum and minimum transverse pore diameters that you want to evaluate, and use these two diameters as boundaries to establish a transverse pore model with continuously changing diameters. Then divide the transverse pore model into 10-20 gradient segments, with each gradient segment having an pore diameter change of 1-2 mm and each gradient segment separated by 0.5 mm, thereby establishing a transverse pore high-throughput evaluation model.

4. The method for high-throughput evaluation and optimization of transverse hole formability in additive manufacturing according to any one of claims 1 to 3, characterized in that: The angle of the inverted V-shaped segment of the transverse hole high-throughput optimization model is set to 90°-150°, and the top of the inverted V-shaped segment is rounded.

5. The method for high-throughput evaluation and optimization of transverse hole formability in additive manufacturing according to any one of claims 1 to 3, characterized in that: Forming quality includes surface integrity, roughness, hardness and / or microstructure.

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