A method for preparing a 3D fused filament printed part with low damage defects and high tensile strength

Abstract

The present invention belongs to the technical field of metal 3D wire melting printing, and discloses a preparation method for a 3D wire melting printed part with low damage defects and high tensile strength, which includes the following steps: performing three-dimensional modeling on the object to be processed, partitioning the three-dimensional model and determining the printing paths for different partitions; according to the printing paths, adopting the arc wire additive manufacturing 3D printing process for corresponding combined processing, thereby obtaining a 3D wire melting printed part with low damage defects and high tensile strength. After modeling the object to be processed, according to the structural characteristics of the object to be processed, different printing paths are adopted for printing. Through the combination of paths such as "Sichuan", "bow", "well", "filling + border", and "field", it can meet the printing of materials with different structures and sizes, thereby breaking through the technical bottleneck of different special alloys in 3D wire melting printing and solving the problem of the crystal structure metallographic transition of special alloys during hot melting-cooling.

Description

Technical Field

[0001] The present invention relates to the technical field of metal 3D fuse printing, and in particular to a method for preparing a 3D fuse printed part with low damage defects and high tensile strength. Background Art

[0002] 3D printing technology has gradually emerged in recent years, especially in the fields of glass / plastic / nylon, but in the field of metal, especially special alloys, due to their own grain structure and mechanical properties, 3D printing technology is difficult to achieve breakthroughs and high-quality metal parts. Even if printed with existing equipment and processes, it is very easy to have quality problems such as fracture of printed samples / uncontrolled deformation / micro cracks caused by uneven local heat / molten pool vacuum at the cross-section interface. These problems affect the promotion and application of products and the healthy development of the industry.

[0003] To this end, the present invention provides a method for preparing a 3D fused filament printed part with low damage defects and high tensile strength. Summary of the invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a 3D fused filament printed part with low damage defects and high tensile strength.

[0005] The method for preparing a 3D fused filament printed part with low damage defects and high tensile strength of the present invention is achieved by the following technical scheme:

[0006] A method for preparing a 3D fused filament printed part with low damage defects and high tensile strength comprises the following steps:

[0007] Step 1, modeling: perform three-dimensional modeling on the object to be processed to obtain a three-dimensional model;

[0008] Step 2, partitions and printing paths of different partitions:

[0009] For the object to be processed with regular structure and thickness ≤10mm, since it is in the same plane as a whole, it is divided into several parallel regions in the same plane along its length direction, and each region is sliced ​​to obtain the corresponding contour. Then, along the length direction of the object to be processed, each contour is filled in turn, thereby obtaining a "chuan"-shaped printing path;

[0010] For objects with regular structure and thickness greater than 10mm, the objects are divided into several parallel regions at different levels along the height direction, and each region is sliced ​​to obtain the corresponding inner and outer contours. Then, along the height direction of the objects, the inner and outer contours are filled in turn, thereby obtaining a "fill + frame" type printing path.

[0011] For the object to be processed with irregular structure, it is divided into several independent regions according to its longitudinal structural characteristics, so as to facilitate printing operations on each region separately, thereby obtaining a "field"-shaped printing path; then, according to the change of the cross section in the height direction of each region, each region is divided into several layers of sub-regions, wherein, in the printing process from bottom to top, the sub-regions of the odd-numbered layers are printed horizontally, and the sub-regions of the even-numbered layers are printed vertically, so as to increase the tensile isotropy of the printed body in different directions by using different printing processes between two adjacent layers of sub-regions, thereby obtaining a "well"-shaped printing path;

[0012] Step 3, according to the printing path of step 2, the arc fuse additive 3D printing process is used to perform corresponding combined processing, thereby obtaining the required 3D fuse print with low damage defects and high tensile strength.

[0013] Furthermore, the metal wire material used for the object to be processed is any one of aluminum, titanium, magnesium and titanium alloy.

[0014] Furthermore, when titanium alloy is used as the metal wire raw material for 3D fused filament printing, the main process parameters are:

[0015] The current is 150-250A, the arc voltage is 10-14V, the ionized argon gas flow rate is 10-14L / min, and the speed is 1500-2500mm / min.

[0016] Furthermore, in step 2, for the object to be processed with a regular structure and a thickness greater than 10 mm, a "bow"-shaped path or a "river"-shaped path is used to completely fill each inner contour.

[0017] Furthermore, in step 2, when filling each inner contour along the height direction of the object to be processed, the printing directions of the processing paths of two adjacent inner contours are perpendicular to each other.

[0018] Furthermore, in the "chuan" type printing path, the printing route moves in a straight line, from one end of the printing area to the other end, then stops after the arc is extinguished, and then restarts a parallel line to start arc printing, and the printing routes are parallel.

[0019] Furthermore, in the “bow”-shaped path, the printing route moves straight from one end of the printing area to the other end without extinguishing the arc, and continues to move straight after making a right-angle turn.

[0020] The second object of the present invention is to provide a 3D fused filament printed part with low damage defects and high tensile strength prepared by the above preparation method.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] After modeling the object to be processed, according to the structural characteristics of the object to be processed, different printing paths are adopted for printing. Through the combination of paths such as "Sichuan", "Bow", "Well", "Filling + Border", and "Field", it is possible to meet the printing of materials with different structures and sizes, thereby breaking through the technical bottleneck of different characteristic alloys in 3D fuse printing and solving the problem of crystal structure metallographic transition in the hot melting-cooling of special alloys. In terms of printing speed, it is more than 20 times the efficiency of powder forming printing by selective laser melting. Secondly, it can perform additive manufacturing of large-sized parts without being restricted by equipment.

[0023] The method of the present invention can avoid tissue defects such as microscopic pores in metal powder printing, and can avoid the phenomenon of molten pool segregation in binary alloys and multi-component alloys, improving the homogenization degree of the secondary molten pool metallographic structure; at the same time, it improves the tissue performance of the printed product and avoids the fusion defect of the printing boundary.

[0024] The present invention realizes the excellent properties of special alloys with low damage defects and high mechanical properties, enabling them to be promoted and applied in high-end fields such as aerospace / medical implants.

[0025] The present invention significantly improves the qualification rate of products and avoids major quality problems such as metal cooling cracks.

[0026] The present invention eliminates the molten pool blind area and printing blind area in the traditional printing technical route, making it possible to eliminate the printing hollow / corner cavity / boundary collapse phenomenon.

[0027] The special alloy prepared by the present invention has isotropic mechanical properties. Due to the scientific and reasonable molten pool solution guiding and layer-by-layer stacking process, the mechanical properties of metal products are consistent in different orientations, such as the elongation and tensile strength in the X / Y / Z axial directions are the same.

[0028] The method of the present invention increases the material utilization rate. Compared with the 50% material utilization rate of the selective laser printing technology for raw materials, the material utilization rate of this process technology reaches 75%-80%.

[0029] In the traditional powder printing process, each component requires a support structure during the printing process, that is, the support structure of the printed component needs to be designed first during printing. After printing, the first process is to remove the support, so at least 30-50% of the material will be removed and wasted. However, in the 3D fuse printing process of the present invention, all the wire materials are completely used for the additive manufacturing of components, without the need for support material design. The material utilization rate is much higher than that of powder printing, and the production efficiency of the present invention is significantly improved. The selective laser printing technology is about 0.2KG / h, and this process technology is about 1.0-5.0KG / h, and the production efficiency is increased by at least 5-20 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of a "Sichuan"-shaped printing path;

[0031] Figure 2 Schematic diagram of a "bow"-shaped printing path;

[0032] Figure 3 Schematic structural diagram of the coin model in Embodiment 2;

[0033] Figure 4 Schematic diagram of partitioning Embodiment 2. Detailed implementation manners

[0034] In consideration of the fact that a large amount of heat energy is generated during the fused filament printing process, the distribution of this heat energy causes non-uniform distribution of the thermal stress of the printed body, thereby causing performance differentiation of the printed parts and adversely affecting the quality. Moreover, in the prior art, 3D fused filament printing is carried out layer by layer using the same process. However, during the printing process, due to the shape change of the printed body, such as the presence of hollow and variable diameter situations, a single circular printing path is not suitable for the printing process of complex parts and special-shaped parts. Moreover, the existing circular printing process for each layer will cause adverse factors such as uneven height of the printing surface and low fused filament accuracy. For this reason, a preparation method for a 3D fused filament printed part with low damage defects and high tensile strength is provided. And below, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0035] The present invention provides a preparation method for a 3D fused filament printed part with low damage defects and high tensile strength, including the following steps:

[0036] Step 1, modeling: performing three-dimensional modeling on the object to be processed to obtain a three-dimensional model;

[0037] It should be noted that the present invention does not limit the metal wire used for the object to be processed, and any one of aluminum, titanium, magnesium, and titanium alloys can be selected. And when using a titanium alloy as the raw material of the metal wire for 3D fused filament printing, its main process parameters are: current 150 - 250A, arc voltage 10 - 14V, ionization argon gas flow rate 10 - 14L / min, speed 1500 - 2500mm / min.

[0038] Step 2, partitioning and printing paths for different partitions:

[0039] For an object to be processed with regular structure and thickness ≤ 10mm, due to its feature of being on the same plane as a whole, it is divided into several parallel regions on the same plane along its length direction, and each region is sliced to obtain the corresponding contour. Then, along the length direction of the object to be processed, each contour is filled in sequence, thereby obtaining a "Sichuan"-shaped printing path;

[0040] For objects with regular structure and thickness greater than 10mm, the objects are divided into several parallel regions at different levels along the height direction, and each region is sliced ​​to obtain the corresponding inner and outer contours. Then, along the height direction of the objects, the inner and outer contours are filled in turn, thereby obtaining a "fill + frame" type printing path.

[0041] For the object to be processed with irregular structure, it is divided into several independent regions according to its longitudinal structural characteristics, so as to facilitate printing operations on each region separately, thereby obtaining a "field"-shaped printing path; then, according to the change of the cross section in the height direction of each region, each region is divided into several layers of sub-regions, wherein, in the printing process from bottom to top, the sub-regions of the odd-numbered layers are printed horizontally, and the sub-regions of the even-numbered layers are printed vertically, so as to increase the tensile isotropy of the printed body in different directions by using different printing processes between two adjacent layers of sub-regions, thereby obtaining a "well"-shaped printing path;

[0042] Step 3, according to the printing path of step 2, the arc fuse additive 3D printing process is used to perform corresponding combined processing, thereby obtaining the required 3D fuse print with low damage defects and high tensile strength.

[0043] The present invention takes into account the size of the printed part, the size of the printing chamber, and the functional properties of the printing body, and therefore, the preparation method of the present invention can realize the preparation process of the present invention through the current general-purpose printing body and the special-type printing body, so as to achieve efficient and accurate printing of printed parts of different sizes, angles, shapes, hollow variable diameters, etc.

[0044] It should be noted that the difference between the above-mentioned river-shaped printing path and the bow-shaped printing path is that the paths they travel are different. Figure 1 As shown in the figure, the Sichuan-type path is a printing route that runs in a straight line without turning. It runs in a straight line from one end of the printing area to the other end, then stops and extinguishes the arc, and then restarts the arc printing in a parallel line. The path is parallel. Figure 2 As shown, the bow-shaped printing path is a walking path with right-angle turns, and there is no arc extinguishing and arc interruption process when turning during printing.

[0045] Example 1

[0046] This embodiment will take the wing of an airplane as an example to specifically explain the above preparation steps of the present invention one by one:

[0047] Step 1: Modeling

[0048] Performing three-dimensional modeling on the aircraft wing as the object to be processed to obtain a three-dimensional model corresponding to the aircraft wing;

[0049] Step 2, partitions and printing paths of different partitions:

[0050] In order to avoid the molten pool segregation phenomenon between the component alloys in the printing material, the present invention divides the wing tip and the wing body into area A and area B respectively according to the different thicknesses and shapes of the wing, and prints area A and area B respectively.

[0051] For the wing-fuselage, its structure is mainly a planar structure with a thickness greater than 10 mm. Therefore, the present invention re-divides the area B corresponding to the wing-fuselage, and divides the area B into several mutually parallel sub-areas on different horizontal planes along the height direction of the area B, and slices each sub-area to obtain the corresponding inner and outer contours, and then fills each inner and outer contour in turn along the height direction of the wing-fuselage, thereby obtaining a "fill + border" type printing path.

[0052] In order to avoid the situation in which the thermal stress of the printed part is unevenly distributed due to the single "circle-by-circle printing path" used in the prior art, which leads to the performance differentiation of the printed part, the present invention prints each of the above-mentioned mutually parallel sub-areas from bottom to top in sequence, and adopts the following method for the sub-areas of odd layers: Figure 1 The "bow" path described above will fill the corresponding inner contour completely. For the sub-areas of the even-numbered layers, the following Figure 2 The “chuan”-shaped path shown in the figure will fill the corresponding inner contour completely; or for the sub-areas of the odd-numbered layers, the following Figure 2 The “chuan”-shaped path shown in the figure fills the corresponding inner contour completely. For the sub-areas of the even-numbered layers, the following Figure 1 The "bow"-shaped path fills the corresponding inner contour completely, and during the printing process, the printing directions of the two adjacent layers of "Chuan"-shaped paths and the "bow"-shaped paths are made perpendicular, so that different printing processes are used between the two adjacent layers of sub-regions to increase the tensile strength isotropy of the printed body in different directions, thereby making the mechanical properties of the printed wing-body in different directions consistent.

[0053] For the wing tip, it is necessary to print on the basis of the wing body, and the present invention takes into account that the structures of different areas of the wing tip on the same horizontal plane are different, and the changes in the cross section along the height direction are different. Therefore, the present invention first divides the area A corresponding to the wing tip into a number of independent sub-areas according to its longitudinal structural characteristics, so as to facilitate the printing operation on each area separately, thereby obtaining a "field"-shaped printing path; then, according to the change of the cross section in the height direction of each area, each area is divided into several layers of sub-areas, and then filled in from bottom to top according to the outline of each sub-area, so as to avoid the occurrence of printing blind areas in the traditional printing process, and can print in sequence according to the structural characteristics of each sub-area, so as to scientifically and rationally perform layered stacking and printing. In order to improve the isotropy of the mechanical properties of the wing tip, the present invention uses horizontal printing for the sub-regions of the odd-numbered layers and vertical printing for the sub-regions of the even-numbered layers during the bottom-up printing process. That is, different printing methods are used for the two adjacent sub-regions. By making the printing directions of the two adjacent sub-regions perpendicular, a "well"-shaped printing path is obtained to increase the tensile isotropy of the printed body in different directions, thereby maintaining the consistent mechanical properties of the printed wing in different directions.

[0054] Example 2

[0055] This embodiment takes a special Ti-Zr alloy printed part as an example to specifically explain the above preparation steps of the present invention one by one:

[0056] Step 1: Modeling

[0057] In this embodiment 1, Figure 3 The coin shown is used as the object to be processed, and three-dimensional modeling is performed on it to obtain a three-dimensional model of the coin;

[0058] Step 2, partitions and printing paths of different partitions:

[0059] The present invention takes into account the different angles, shapes, and hollow structures of coins, and the different structures in different areas on the same horizontal plane, so the coin model is divided into four areas in an "X" shape, such as Figure 4As shown, "1, 2, 3, 4" represent four different areas, that is, a "field" type printing path is executed on the coin model. Then, each area is divided into several layers of sub-areas along the height direction of the four areas, and then each sub-area is sliced ​​to obtain the inner and outer contours of each sub-area. The outer contour is printed separately according to its structure, and then the inner contour is filled using a "bow" type printing path. In the process of printing from bottom to top, the "bow" type printing process used in the sub-areas of the odd layers is printed in the horizontal direction, and the "bow" type printing process used in the sub-areas of the even layers is printed in the longitudinal direction, so that the tensile isotropy of the printed body in different directions is increased by using different printing processes between two adjacent layers of sub-areas.

[0060] In this embodiment, under the condition of 1950°C, the above steps are combined with the arc fuse additive 3D printing process to perform corresponding combined processing, so that the thermal conductivity of the cooling molten pool printed in different time periods is unified, and the metal molten pools at different printing interfaces influence and fuse each other, thereby improving the uniformity and consistency of mechanical properties, and avoiding workpiece abnormalities caused by the superposition and consistency of quality defects of traditional printing technology.

[0061] It should be noted that in actual operation, the above-mentioned three-dimensional model of the aircraft wing or the three-dimensional model of the coin can be exported as an STL file representing the surface information of the model stored in binary form, the coordinates and vector information of the facet in the STL file can be read, and then partitioned according to the above steps, divided into regions and / or sub-regions, and then sliced ​​in layers (according to the coordinates and vector information of the facet in the STL file, the facets can be sorted from small to large according to the Z coordinate, and then sliced ​​in the layer thickness direction of the Z coordinate) and path planning can be obtained. The printing path represented by an ordered point cloud can be obtained, and the obtained printing path can be converted into the robot language to obtain the robot motion printing instruction. Then, the robot motion printing instruction is imported into the robot control platform, and the arc fuse 3D printing manufacturing of each partition part is carried out using appropriate process parameters. For example, in the printing process of the above-mentioned aircraft wings or coins, according to a preferred embodiment of the present invention, 3D fuse printing is performed using titanium alloy as the metal wire raw material, and is performed based on the following process parameters: current is 150-250A, arc voltage is 10-14V, ionized argon gas flow rate is 10-14L / min, and speed is 1500-2500mm / min.

[0062] After printing one part, the component is transformed to the appropriate position through the positioner, and the above steps are repeated to print the next part until the final product is obtained.

[0063] After modeling the object to be processed, according to the structural characteristics of the object to be processed, different printing paths are adopted for printing. Through the combination of paths such as "Sichuan", "Bow", "Well", "Filling + Border", and "Field", it is possible to meet the printing of materials with different structures and sizes, thereby breaking through the technical bottleneck of different alloys in 3D fuse printing and solving the problem of crystal structure metallographic transition in the hot melting-cooling of special alloys. In terms of printing speed, it is more than 20 times the efficiency of selective laser melting powder forming printing. Secondly, it can perform additive manufacturing of large-size parts without being restricted by equipment. Moreover, in the 3D fuse printing process of the present invention, all wire materials are completely used for the additive manufacturing of parts, without the need for support material design, and the material utilization rate is much higher than that of powder printing, and the production efficiency of the present invention is significantly improved. The selective laser printing technology is about 0.2 KG / h, and this process technology is 1.0 - 5.0 KG / h, and the production efficiency is increased by at least 5 - 20 times.

[0064] Obviously, the above-mentioned embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a 3D fused filament printed part with low damage defects and high tensile strength, characterized in that: The steps include the following: Step 1, Modeling: Perform three-dimensional modeling on the object to be processed to obtain a three-dimensional model; Step 2, Partitioning and printing paths for different partitions: For the object to be processed with regular structure and thickness ≤ 10 mm, since its whole is in the same plane, along its length direction, it is divided into several mutually parallel regions in the same plane, and each region is sliced to obtain the corresponding contour. Then, along the length direction of the object to be processed, each contour is filled in sequence, thereby obtaining a "Sichuan"-type printing path; For the object to be processed with regular structure and thickness > 10 mm, it is divided into several mutually parallel regions in different horizontal planes along its height direction, and each region is sliced to obtain the corresponding inner and outer contours. Then, along the height direction of the object to be processed, each inner contour and outer contour are filled in sequence, thereby obtaining a "filling + border"-type printing path; For the object to be processed with irregular structure, according to its longitudinal structural characteristics, it is divided into several mutually independent regions to facilitate printing operations on each region respectively, thereby obtaining a "field"-type printing path; Then, according to the change of the cross-section in the height direction of each region, each region is respectively divided into several sub-regions of layers, and each layer of sub-regions is sliced to obtain the corresponding contour. Then, the contours are printed successively from bottom to top; and during the printing process, the sub-regions of odd layers are printed horizontally, and the sub-regions of even layers are printed vertically, thereby obtaining a "well"-type printing path; Step 3, According to the printing path in Step 2, adopt the arc wire additive 3D printing process to perform corresponding combined processing, and further obtain the required 3D fuse printing part with low damage defects and high tensile strength; In Step 2, for the object to be processed with regular structure and thickness > 10 mm, each inner contour is filled completely by adopting a "bow"-type path or a "Sichuan"-type path; In Step 2, when filling each inner contour along the height direction of the object to be processed, the printing directions of the processing paths of two adjacent inner contours are perpendicular to each other; In the "Sichuan"-type printing path, the printing route walks in a straight line, extinguishes the arc and stops after walking in a straight line from one end of the printing area to the other end, and then starts a new parallel line to start arc printing. The printing routes are parallel to each other; In the "bow"-type path, the printing route walks in a straight line from one end of the printing area to the other end, does not extinguish the arc, and continues to walk in a straight line after turning at a right angle.

2. The preparation method according to claim 1, characterized in that The metal wire used for the object to be processed is any one of aluminum, titanium, magnesium and titanium alloy.

3. The preparation method according to claim 1, characterized in that: When using titanium alloy as the raw material of the metal wire for 3D fuse printing, its main process parameters are: Current 200 A, arc voltage 12 V, ionization argon gas flow rate 12 L / min, speed 2000 mm / min.

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