Variable-layer-thickness printing method based on SLM forming part characteristics

Abstract

The invention relates to a variable layer thickness printing method based on SLM (selective laser melting) forming part characteristics, which comprises the following specific steps of: dividing a part into an external surface / thin wall of a quality priority part and an internal filling / entity of an efficiency priority part according to the part characteristics and use performance; respectively slicing the quality priority part and the efficiency priority part obtained by the S I by using slicing software according to the required layer thickness, and setting a proper scanning sequence and an optimized scanning strategy for the sliced model; large-layer-thickness process parameters are given to the efficiency priority part, small-layer-thickness process parameters are given to the quality priority part, and a workpiece or a sample with the good surface metallurgy quality is obtained through SLM printing. A set of complete scheme for improving the printing efficiency through a large and small layer thickness method is formed, the surface metallographic phase of the finished product has no other defects except pores, and the effect is good.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing (SLM) printing technology, and in particular to a variable layer thickness printing method based on SLM formed part features. Background Art

[0002] The diversity of additive manufacturing application markets has driven the rapid development of additive manufacturing technology. For example, in the current civilian market, products are relatively cost-sensitive and demand very high forming efficiency. Most civilian products have a large number of solid objects but a relatively simple internal structure, with strict technical specifications for hardness and surface finish. Conventional printing methods, such as those used in the mold industry, often use large layer thicknesses to print parts without surface precision requirements and small layer thicknesses to meet product quality and surface finish requirements. This method improves efficiency and shortens printing time compared to traditional methods. However, with the rapid iteration and update of products, it still cannot meet customer needs.

[0003] To meet such needs, the variable layer thickness interface remelting technology is used to improve printing efficiency. The quality optimization part and the efficiency optimization part are sliced ​​separately. The efficiency optimization part is printed using large layer thickness technology to shorten printing time and improve efficiency. The quality optimization part is printed using small layer thickness to ensure the accuracy of its fine structure and a high polishing level to meet product performance. The printing method of the present invention can not only obtain products or test pieces with good metallurgical quality, but also increase its printing efficiency by more than 1.5 times. With the advancement of additive manufacturing SLM printing technology and the improvement of large layer thickness technology, the use of the present invention can still improve printing efficiency. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In response to the shortcomings of the existing technology, the present invention provides a variable layer thickness printing method based on the characteristics of SLM formed parts. It adopts variable layer thickness interface remelting overlap technology. By reasonably setting the scanning sequence, remelting spacing and optimizing the scanning strategy, a workpiece or sample with good metallurgical effect can be obtained. Compared with the traditional civilian industry printing method, the printing efficiency is improved by about 1.5 times, the printing time is shortened, and costs are saved. The present invention has formed a complete set of solutions for improving printing efficiency by using large and small layer thickness methods. The metallographic surface of the finished product has no other defects except pores, and the effect is good.

[0006] (2) Technical solution

[0007] To achieve the above-mentioned object, the present invention provides the following technical solution: a variable layer thickness printing method based on the characteristics of SLM formed parts, comprising the following specific steps:

[0008] S1: Based on part characteristics and performance, parts are divided into quality-focused exterior surfaces / thin-walled areas and efficiency-focused interior fill / solid parts. Parts are partitioned to differentiate between quality-critical exterior surfaces and thin-walled areas and efficiency-critical interior fill / solid parts. This allows for flexible control of process parameters for different parts of the part to achieve optimal manufacturing results.

[0009] S2: Use slicing software to slice the quality-prioritized and efficiency-prioritized parts obtained in SI separately according to the required layer thickness. After slicing, set the appropriate scanning order and optimize the scanning strategy. By using slicing software to slice the quality-prioritized and efficiency-prioritized parts separately, and set the appropriate scanning order and optimize the scanning strategy according to the required layer thickness, this can improve the efficiency and print quality of the printing process and ensure the accuracy and stability of the printed parts.

[0010] S3: Assigning high layer thickness process parameters to efficiency-focused areas and low layer thickness process parameters to quality-focused areas, resulting in workpieces or specimens with excellent surface metallurgical quality through SLM printing. Based on part quality requirements, different process parameters are assigned to different areas, with high and low layer thicknesses. This allows for efficient printing of internal fills and solid parts while ensuring print quality for external surfaces and thin-walled areas. SLM printing technology can produce workpieces or specimens with excellent surface metallurgical quality, meeting the quality requirements of diverse applications.

[0011] Preferably, the step S1 is to use software to decompose the workpiece model into a quality-priority part and an efficiency-priority part according to the workpiece model characteristics, and to set the remelting distance required for the interface between the two on the model. Specifically, the technical effects of using software to decompose the workpiece model into a quality-priority part and an efficiency-priority part according to the workpiece model characteristics, and to set the remelting distance required for the interface between the two on the model are as follows:

[0012] Efficient workpiece decomposition: By analyzing workpiece characteristics, the software can accurately decompose the workpiece into quality- and efficiency-focused components. This decomposition method can improve the efficiency of the production process and ensure reasonable control of overall manufacturing costs.

[0013] Accurately setting the interface remelting distance: During the decomposition process, it is crucial to set the required remelting distance between the two interfaces. By accurately setting the interface remelting distance, you can fully utilize the advantages of efficiency-first parts while maintaining part quality. This helps optimize the manufacturing process and improve production efficiency.

[0014] Precise process control: By decomposing the workpiece and setting the interface remelting distance, appropriate process parameters can be specified for each part based on the part's characteristics and requirements. For example, a smaller layer thickness can be set for quality-focused parts to achieve higher surface quality and accuracy, while a larger layer thickness can be set for efficiency-focused parts to increase printing speed.

[0015] Preferably, the specific operation process of S2 is: importing the model into the slicing software, slicing the efficiency-prioritized part with large slice thickness and the quality-prioritized part with small slice thickness, selecting a suitable scanning sequence setting for the sliced ​​model, and optimizing the scanning strategy.

[0016] Preferably, the specific operation process of S3 is: assigning process parameters to the models processed by S1 and S2, and obtaining a workpiece or sample with good metallurgical quality through SLM printing.

[0017] Preferably, the optimization of the scanning strategy in S2 requires closing the contour of the efficiency-first part.

[0018] Preferably, in said S3, the difference in laser absorption rate and heat dissipation rate between the powder state and the printed state of the interface remelting area of ​​the quality priority part and the efficiency priority part is taken into account during the SLM printing process. The interface remelting area of ​​the two is generally selected to be about 0.3mm-0.6mm, among which the metallurgical quality of the 0.4mm interface remelting area is the best. Taking into account the difference in laser absorption rate and heat dissipation rate between the powder state and the printed state of the interface remelting area of ​​the quality priority part and the efficiency priority part during the SLM printing process, and selecting a suitable interface remelting area, the following technical effects are achieved:

[0019] Optimal metallurgical quality: By selecting an appropriate interface remelting zone, particularly a 0.4 mm interface remelting zone, optimal metallurgical quality can be achieved. Within this remelting zone, better powder melting and bonding can be achieved, thereby improving the metallurgical properties of the part.

[0020] Adaptability to different materials and requirements: Different materials may exhibit differences in laser absorption and heat dissipation rates in both powder and printed states. Therefore, the interface remelting area can be selected based on the specific material characteristics to accommodate the printing requirements and achieve optimal metallurgical quality.

[0021] Controlling the heat-affected zone: Selecting an appropriate interface remelting zone can help control the size of the heat-affected zone. By controlling the extent of the interface remelting zone, you can control the local heat input and heat dissipation rate, thereby reducing thermal stress and deformation, and improving the accuracy and stability of the printed workpiece.

[0022] Preferably, the variable layer thickness applicable to the present method is generally in a "multiple" relationship, and the layer thickness of the efficiency priority part is an integer multiple of the layer thickness of the quality priority part.

[0023] Preferably, the materials suitable for SLM printing using this method are high-temperature alloys, aluminum alloys, stainless steel or titanium alloy powders.

[0024] Preferably, the outer surface / thin wall of the quality-prioritized portion is smaller than 3 mm in size, and the inner filling / solid portion of the efficiency-prioritized portion is larger than 3 mm in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0026] Figure 1 This is a schematic diagram of processing a horizontal interface based on a variable layer thickness model in Example 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of processing a horizontal interface based on a variable layer thickness model in Example 1 of the present invention;

[0028] Figure 3 This is a cross-sectional metallographic structure diagram prepared based on variable layer thickness in Example 1 of the present invention;

[0029] Figure 4 This is a longitudinal cross-sectional metallographic structure diagram prepared based on variable layer thickness in Example 1 of the present invention.

[0030] (3) Beneficial effects

[0031] Compared with existing technologies,

[0032] This invention utilizes variable layer thickness interface remelting and overlapping technology. By rationally configuring the scanning sequence, remelting spacing, and optimizing the scanning strategy, it can produce workpieces or specimens with excellent metallurgical properties. Compared with traditional civilian printing methods, this method improves printing efficiency by approximately 1.5 times, shortening printing time and saving costs. This invention provides a comprehensive solution for improving printing efficiency using variable layer thickness methods. The finished product exhibits surface metallographic defects other than pores, demonstrating excellent results. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0034] Example 1:

[0035] Die steel 18Ni300 was selected as the SLM printing powder, and a small mold model (size 40×40×40mm) was selected as the printing product. The model was shelled and Boolean operations were performed using software. The processed model was sliced ​​using HBDBuildExpert software, and the scanning strategy, remelting spacing, and scanning strategy were optimized. SLM printing produced a workpiece with good metallurgical effects. The basic operation steps are as follows:

[0036] Step 1: Use software to decompose the model into two or more models: efficiency optimization and quality optimization. Set the remelting spacing on the model. Use HBDBuild Expert software to slice the model according to the required layer thickness. Set the appropriate scanning order (efficiency optimization first, then quality optimization) and optimize the scanning strategy for the sliced ​​model.

[0037] Step 2: Assign the required standard process parameters of different layer thicknesses to the processed model, and obtain a workpiece or sample with good surface metallurgical quality through SLM printing.

[0038] The steps of a variable layer thickness printing method based on SLM formed part features are as follows:

[0039] 1) Perform shell extraction and Boolean operations on the mold (size 40×40×40 mm). The layer thickness of the quality optimization part is 1.4 mm, and the layer thickness of the efficiency optimization part is 38.8 mm. The remelting area of ​​both is 0.4 mm.

[0040] 2) Use HBDBuildExpert software to slice the model according to the required layer thickness, set the appropriate scanning order (generally the efficiency optimization part first and then the quality optimization part) and optimize the scanning strategy (turn off the filling contour in the efficiency optimization part during optimization).

[0041] 3) The processed model was assigned standard process parameters. For the efficiency optimization part, a large layer thickness (60 μm) process parameter was selected, and for the quality optimization part, a small layer thickness (30 μm) process parameter was selected. Through SLM printing, a surface with good metallurgical effect was obtained. The metallographic results are shown in the attached figure.

[0042] Note: This invention is suitable for workpieces with complex structures, and the printing effect of multi-layer structures is still good. The thickness of the layer of the quality-optimized part of this invention can reach 0.5mm, and its fine structures can also be printed with this invention to improve efficiency.

[0043] Note: The product workpiece of the present invention can obtain a metallographic structure with no other defects except a small amount of pores, and the pore diameter is less than 40μm.

[0044] In summary, the present invention uses a variable layer thickness method to improve printing efficiency, and the efficiency can be increased by more than 1.5 times. The present invention provides a complete set of printing methods in the field of additive manufacturing, which is simple in process, saves time and cost, and can meet customer needs with higher quality. The present invention selects the appropriate remelting spacing, scanning sequence and scanning strategy optimization by overlapping the remelting areas of the efficiency optimization part and the quality optimization part, and obtains a test piece with good metallurgical quality through SLM printing.

[0045] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A variable layer thickness printing method based on SLM formed part features, characterized in that: The specific steps include: S1: Based on part features and performance, parts are divided into external surface / thin wall for quality priority and internal filling / solid for efficiency priority; S2: Use slicing software to slice the quality priority part and efficiency priority part obtained by SI according to the required layer thickness, and set the appropriate scanning order and optimize the scanning strategy for the sliced ​​model; S3: Assign large layer thickness process parameters to the efficiency priority part and small layer thickness process parameters to the quality priority part, and obtain workpieces or samples with good surface metallurgical quality through SLM printing.

2. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: The specific method of S1 is to use software to decompose the workpiece model into a quality priority part and an efficiency priority part according to the features of the workpiece model, and at the same time set the remelting distance required for the interface between the two on the model.

3. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: The specific operation process of S2 is: import the model into the slicing software, slice the efficiency-first part with a large layer thickness, slice the quality-first part with a small layer thickness, select a suitable scanning sequence setting for the sliced ​​model, and optimize the scanning strategy.

4. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: The specific operation process of S3 is: assigning process parameters to the models processed by S1 and S2, and obtaining a workpiece or sample with good metallurgical quality through SLM printing.

5. The variable layer thickness printing method based on SLM formed part features according to claim 3 is characterized in that: To optimize the scanning strategy in S2, it is necessary to close the contour of the efficiency priority part.

6. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: In S3, the differences in laser absorption rate and heat dissipation rate in the powder state and the printed state in the interface remelting area of ​​the quality priority part and the efficiency priority part are taken into consideration during the SLM printing process. The interface remelting area of ​​the two is generally selected to be around 0.3mm-0.6mm, among which the 0.4mm interface remelting area has the best metallurgical quality.

7. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: The variable layer thickness applicable to the present method is generally in a "multiple" relationship, where the layer thickness of the efficiency priority part is an integer multiple of the layer thickness of the quality priority part.

8. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: The materials suitable for SLM printing by this method are high-temperature alloys, aluminum alloys, stainless steel or titanium alloy powders.

9. The variable layer thickness printing method based on SLM formed part features according to claim 1, characterized in that: The outer surface / thin wall of the quality priority part is smaller than 3 mm in size, and the inner filling / solid of the efficiency priority part is larger than 3 mm in size.

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