High-throughput evaluation and optimization method for formability of additive manufacturing suspended structure

Abstract

The invention discloses a high-throughput evaluation and optimization method for formability of an additive manufacturing suspended structure. The method comprises the following steps: establishing a suspended high-throughput evaluation model; preparing an evaluation model by adopting the target process parameters; based on the formability of different suspension lengths, determining a limit forming size, and establishing a high-throughput optimization model of a corresponding structure size for a suspension structure of which the suspension length of an actual part is greater than the limit forming size; preparing an optimization model by adopting corresponding process parameters; and preparing a verification piece based on the optimal model structure with the optimal formability. By means of the method, the suspended structure 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 belongs to the technical field of metal additive manufacturing, and in particular relates to a high-throughput evaluation and optimization method for the formability of an additively manufactured suspended structure. Background Art

[0002] High-energy beam metal additive manufacturing mainly includes selective laser melting (SLM), selective electron beam melting (EBM), and direct energy deposition (DED). These processes use high-energy beams to melt powder and stack metal materials layer by layer into the desired shape, which is conducive to the preparation of parts with complex shapes and liberates the freedom of design. However, when preparing parts with suspended structures, it is necessary to selectively add supports based on the size of the suspended structure to ensure the formability of the parts. The limit size of the support required for different materials and different process parameters is different. Therefore, for each material and process parameter, it is necessary to obtain the limit forming size of the suspended structure to assist in model preprocessing and optimization. Discrete specimens are usually used to obtain the formability of suspended 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 size, you can only further increase the number of 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 suspended structures in additive manufacturing. This method takes the minimum processing allowance as the criterion, can realize the rapid screening and optimization of the ultimate forming dimensions of the suspended length, and improve the efficiency of model optimization.

[0004] To this end, the present invention provides a high-throughput evaluation and optimization method for the formability of an additively manufactured suspended structure, which is characterized by comprising the following steps: Step 1: Establish a high-throughput evaluation model in which the overhang length gradually changes along the width direction, and the overhang thickness of the high-throughput evaluation model is consistent with the overhang thickness of the actual component model to be printed; Step 2: Assign process parameters to the suspended high-throughput evaluation model, prepare additive manufacturing high-throughput specimens, and analyze whether the forming quality of the high-throughput specimens at different cantilever lengths meets the design technical requirements, and determine the limit suspended length that meets the design technical requirements; Step 3: Compare the maximum overhang length with the actual overhang length of the component model to be printed. If the actual overhang length to be printed is less than the maximum overhang length, directly use the actual component model to be printed for printing. If the actual overhang length to be printed is greater than the maximum overhang length, go to step 4. Step 4: Based on the actual hanging length of the model of the component to be printed, a hanging high-throughput optimization model is established. The hanging high-throughput optimization model includes a base segment, a hanging segment arranged on the base segment, and a 45° chamfer arranged at the connection between the bottom of the hanging segment and the base segment. The hanging length and thickness of the hanging segment are consistent with the actual model of the component to be printed, and the length dimension of the chamfer changes gradually along the width direction of the hanging segment. Step 5: Assign the same process parameters as in step 2 to the suspended high-throughput optimization model, prepare additive manufacturing high-throughput specimens, and analyze the forming quality of the specimens at different chamfer lengths to determine the minimum chamfer length allowed when the forming quality meets the design technical requirements; A 45° chamfer is added to the root corner of the suspended structure of the actual component model to be printed. The length of the chamfer is the minimum length of the chamfer determined above, so as to optimize the actual component model to be printed, and use the optimized component model to complete the printing of the part.

[0005] Specifically, the suspended section is composed of a plurality of gradient sections, and the suspended lengths of the plurality of gradient sections gradually decrease or increase along the width direction.

[0006] Specifically, the maximum and minimum overhang lengths to be evaluated were determined, and a model with continuous changes in the overhang length was established with these two length dimensions as boundaries. The model was then divided into 10-20 gradient segments, with each gradient segment length varying by 1-2 mm and each gradient segment spaced 0.5 mm apart, thereby establishing an overhang high-throughput evaluation model.

[0007] Specifically, the chamfer length size of the overhang high-throughput optimization model varies in the range of 1 / 10*overhang length to 2 / 3*overhang length.

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

[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 to establish a high-throughput evaluation and optimization model for overhangs. The high-throughput evaluation model can use a high-throughput sample to quickly obtain the ultimate forming dimensions of the overhang length, and quickly screen the forming dimensions and forming processes that meet the technical conditions based on the technical requirements of the target parts, and determine the size range for direct forming. There is no need to repeatedly refine the dimensional structure to obtain the required forming capacity as in the case of discrete samples. The high-throughput optimization model can quickly screen the optimization scheme for the overhang model with the minimum machining allowance, greatly reducing the difficulty of post-processing, which is conducive to improving the efficiency of process and model optimization iterations, 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 is a flow chart of the present invention; Figure 2 Schematic diagram of the suspended high-throughput evaluation model; Figure 3 Schematic diagram of the suspended high-throughput optimization model; 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 the formability of an additively manufactured suspended structure, comprising the following steps: Step 1: Establish a high-throughput evaluation model in which the overhang length gradually changes along the width direction. The overhang thickness of the high-throughput evaluation model is consistent with the overhang thickness of the actual component model to be printed.

[0014] Specifically, the suspended high-throughput evaluation model includes a base segment and a suspended segment arranged on the base segment, the suspended segment is composed of a plurality of gradient segments, and the suspended lengths of the plurality of gradient segments gradually decrease or increase along the width direction, such as Figure 1 shown.

[0015] In practical applications, the specific process of establishing the overhang segment is as follows: determine the maximum and minimum overhang lengths to be evaluated, and use these two length dimensions as boundaries to establish a model with continuous changes in overhang length. In order to reduce the mutual influence between the formability of different overhang lengths, the model is divided into 10-20 gradient segments, and the length of each gradient segment changes by 1-2mm (based on the difference between the maximum and minimum overhang lengths), and each gradient segment is separated by 0.5mm, so as to establish a high-throughput evaluation model for overhang.

[0016] Step 2: Assign process parameters to the suspended high-throughput evaluation model, use the metal powder to be evaluated as raw material, prepare additive manufacturing high-throughput samples, and analyze whether the forming quality of the high-throughput samples at different cantilever lengths meets the design technical requirements, and determine the limit suspension length that meets the design technical requirements; Step 3: Compare the maximum overhang length with the actual overhang length of the component model to be printed. If the actual overhang length to be printed is less than the maximum overhang length, directly use the actual component model to be printed for printing. If the actual overhang length to be printed is greater than the maximum overhang length, go to step 4 to further optimize the actual component model to be printed. Step 4: Based on the actual suspended length of the model of the component to be printed, a suspended high-throughput optimization model is established. The suspended high-throughput optimization model includes a base segment, a suspended segment arranged on the base segment, and a 45° chamfer arranged at the connection between the bottom of the suspended segment and the base segment. By adding a 45° chamfer at the root corner of the suspended segment (forming a chamfered boss), the suspended length and thickness of the suspended segment are consistent with the actual model of the component to be printed, and the length dimension of the chamfer gradually changes along the width direction of the suspended segment. Step 5: Assign the same process parameters as in step 2 to the suspended high-throughput optimization model, use the metal powder to be optimized as the raw material, prepare the additive manufacturing high-throughput sample, and analyze the forming quality of the sample at different chamfer lengths to determine the minimum chamfer length allowed when the forming quality meets the design technical requirements; A 45° chamfer is added to the root corner of the suspended structure of the actual component model to be printed to form a chamfered boss that supports the suspended section (which will be removed by machining later). The length of the chamfer is the minimum chamfer length determined above, so as to optimize the actual component model to be printed, and use the optimized component model to complete the printing of the part.

[0017] Specifically, a 45° chamfer is added at the overhang corner, and the chamfer length is set within the range of 2 / 3*overhang length to 1 / 10*overhang length. This is because usually when the chamfer length is less than 1 / 10*overhang length, the formability of the overhang structure cannot be improved by the structure. When the chamfer size is greater than 2 / 3*overhang length, the addition of excessive chamfer allowance is contrary to the minimum machining allowance goal.

[0018] The present invention uses the minimum machining allowance as a criterion to establish a high-throughput evaluation and optimization model for overhangs. The high-throughput evaluation model can use a high-throughput sample to quickly obtain the ultimate forming size of the overhang length, and quickly screen the forming size and forming process that meet the technical conditions based on the technical requirements of the target parts, and determine the size range for direct forming. There is no need to repeatedly refine the dimensional structure to obtain the required forming capacity as in discrete samples. The high-throughput optimization model can quickly screen the optimization solution for the overhang model with the minimum machining allowance, greatly reducing the difficulty of post-processing of the chamfered boss, which is conducive 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.

[0019] like Figure 2A suspended high-throughput evaluation model was established, and the suspended length was set to 0-5 mm, divided into 10 gradient segments, each with a suspension length change of 0.5 mm, and each gradient segment was separated by 0.5 mm.

[0020] Using GH4169 alloy powder as raw material, the evaluation model was prepared by selective laser melting equipment, and three different scanning speeds were set. Among them, 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. Warping and deformation are prone to occur during the forming process of the suspended structure. During the forming process, the model printing of the warped area needs to be stopped in time to avoid damaging the scraper and affecting the forming.

[0021] A 3D scanner was used to detect deformation in the area without obvious warping in the evaluation model. As the overhang length increases, the overhang deformation increases. The sample with a scanning speed of 1360mm / s will have a deformation greater than 0.2mm (design requirement) when the overhang length is greater than 3.4mm; the sample with a scanning speed of 1160mm / s will have a deformation greater than 0.2mm when the overhang length is greater than 3.1mm; the sample with a scanning speed of 1160mm / s will have a deformation greater than 0.2mm when the overhang length is greater than 2.3mm.

[0022] In actual parts, there is a 5mm overhang structure that cannot be formed directly. Therefore, based on the 5mm overhang length, a high-throughput optimization model was established, with the chamfer length ranging from 1 to 2.5mm. The same process parameters were set to complete the model preparation.

[0023] A 3D scanner was used to detect deformation in the area without obvious warping in the optimized model. As the chamfer length increased, the deformation of the overhang became smaller and smaller. The sample with a scanning speed of 1360mm / s had a deformation greater than 0.2mm when the chamfer length was less than 1.3mm (limit forming chamfer size); the sample with a scanning speed of 1160mm / s had a deformation greater than 0.2mm when the chamfer length was less than 1.7mm; the sample with a scanning speed of 1360mm / s had a deformation greater than 0.2mm when the chamfer length was less than 2mm.

[0024] Based on the above, the limit forming size of the suspended structure and the optimized chamfer length of the GH4169 alloy at different scanning speeds can be obtained, and a structure with high formability and minimum processing allowance can be obtained.

[0025] 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 the formability of suspended structures in additive manufacturing, characterized in that: The steps include: Step 1: Establish a high-throughput evaluation model in which the overhang length gradually changes along the width direction, and the overhang thickness of the high-throughput evaluation model is consistent with the overhang thickness of the actual component model to be printed; Step 2: Assign process parameters to the suspended high-throughput evaluation model, prepare additive manufacturing high-throughput specimens, and analyze whether the forming quality of the high-throughput specimens at different cantilever lengths meets the design technical requirements, and determine the limit suspended length that meets the design technical requirements; Step 3: Compare the maximum overhang length with the actual overhang length of the component model to be printed. If the actual overhang length to be printed is less than the maximum overhang length, directly use the actual component model to be printed for printing. If the actual overhang length to be printed is greater than the maximum overhang length, go to step 4. Step 4: Based on the actual suspended length of the model of the component to be printed, a suspended high-throughput optimization model is established. The suspended high-throughput optimization model includes a base segment, a suspended segment arranged on the base segment, and a 45° chamfer arranged at the connection between the bottom of the suspended segment and the base segment. The suspended length and thickness of the suspended segment are consistent with the actual model of the component to be printed, and the length dimension of the chamfer changes gradually along the width direction of the suspended segment. Step 5: Assign the same process parameters as in step 2 to the suspended high-throughput optimization model, prepare additive manufacturing high-throughput specimens, and analyze the forming quality of the specimens at different chamfer lengths to determine the minimum chamfer length allowed when the forming quality meets the design technical requirements; A 45° chamfer is added to the root corner of the suspended structure of the actual component model to be printed. The length of the chamfer is the minimum length of the chamfer determined above, so as to optimize the actual component model to be printed, and use the optimized component model to complete the printing of the part.

2. The high-throughput evaluation and optimization method for additive manufacturing suspended structure formability according to claim 1, characterized in that: The suspended section is composed of a plurality of gradient sections, and the suspended lengths of the plurality of gradient sections gradually decrease or increase along the width direction.

3. The high-throughput evaluation and optimization method for additive manufacturing suspended structure formability according to claim 2, characterized in that: Determine the maximum and minimum overhang lengths that you want to evaluate, and use these two length dimensions as boundaries to establish a model with continuous changes in overhang length. Then divide the model into 10-20 gradient segments, with each gradient segment length varying by 1-2 mm and each gradient segment spaced 0.5 mm apart, to establish an overhang high-throughput evaluation model.

4. The high-throughput evaluation and optimization method for additive manufacturing suspended structure formability according to any one of claims 1 to 3, characterized in that: The chamfer length size of the overhang high-throughput optimization model varies in the range of 1 / 10*overhang length to 2 / 3*overhang length.

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

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