Laser selective melting gradient additive-based easily removable support device and method

Abstract

This invention discloses an easily removable support device and method based on laser selective melting gradient additive manufacturing. The device includes a support structure, a part body, an additive substrate, a first interface layer, and a second interface layer. The support structure is made of aluminum alloy powder, and the part body is made of metal powder that does not react with alkaline solutions. Both the first and second interface layers are composed of a mixture of aluminum alloy powder and the metal powder from the part body. The mass fraction of aluminum alloy powder in each additive cladding layer decreases or increases progressively, forming a linear compositional transition. The support method includes: support structure design, gradient additive manufacturing of the part, removal of the support structure and interface layers, heat treatment of the part, and post-processing of the part. By placing the entire additive part in an alkaline etching solution, the aluminum alloy support structure and interface layers are selectively dissolved and removed, while the part body remains undamaged. This invention achieves easy removal of the support structure and high-quality bonding of dissimilar material interfaces.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to an easily removable support device and method based on laser selective melting gradient additive manufacturing. Background Technology

[0002] Selective laser melting (SLM) is an additive manufacturing technology that selectively melts a bed of metal powder layer by layer using a laser. It features high forming accuracy, good performance, and the ability to manufacture parts with complex shapes, and has important applications in aerospace, petrochemical and other fields.

[0003] During SLM (Surface Mount Technology), the molten pool formed by the melting of powder in the overhanging parts collapses under its own gravity and capillary action, causing warping or slag buildup defects in the parts. Support structures are needed to prevent deformation and aid in heat conduction. Currently, these support structures are mainly removed manually by fitters through cutting and grinding. This method is not only difficult to remove poorly removable support structures from deep cavities in conduit parts, but also involves a heavy workload for workers, harsh working conditions, and inconsistent manual operation. Therefore, a new, easily removable support device and method are urgently needed.

[0004] Patent application CN 117047133 A discloses a method for removing supports in additive manufacturing of metal parts. This method controls process parameters to ensure the solidification rate of the support structure is lower than that of the part during additive manufacturing. The support is removed by utilizing its rapid dissolution rate during chemical etching. While this method accelerates support removal, it not only narrows the forming process window for the part but also fails to selectively remove the support structure using the etching solution, potentially damaging the part itself during the dissolution process. Summary of the Invention

[0005] The purpose of this invention is to provide an easily removable support device and method based on laser selective melting gradient additive manufacturing, thereby solving the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention employs the following technical solution: An easily removable support device based on laser selective melting gradient additive manufacturing includes a support structure, a part body, an additive substrate, a first interface layer, and a second interface layer. With the additive manufacturing direction as the positive direction, the support structure and the upper part body are transitioned through a first interface layer; the support structure and the lower part body or additive substrate are transitioned through a second interface layer. The support structure is used to support the suspended part during the additive manufacturing process of the part body, and its raw material is aluminum alloy powder; the raw material of the part body is metal powder other than aluminum alloy that does not react with alkaline solution. The raw material of the first interface layer is a mixture of aluminum alloy powder for printing the support structure and metal powder for printing the part body; the first interface layer contains multiple additive cladding layers with linear transition of components, and the mass fraction of aluminum alloy powder in each additive cladding layer decreases layer by layer from the support structure to the part body. The raw material of the second interface layer is a mixture of aluminum alloy powder for printing the support structure and metal powder for printing the part body; the second interface layer contains multiple additive cladding layers with linearly transitioning components, and the mass fraction of aluminum alloy powder in each additive cladding layer increases progressively from the part body or additive substrate to the support structure.

[0007] Furthermore, taking the additive manufacturing direction as the positive direction, the lower side of the first interface layer is a supporting structure, and the upper side is the part body; the first interface layer includes j An additive cladding layer with linear transition of components; wherein, from bottom to top, the first... i In the raw materials for each additive cladding layer, the mass fraction of aluminum alloy powder is: ×100%; of which i It is a positive integer, and 1 ≤ i ≤ j .

[0008] Furthermore, taking the additive manufacturing direction as the positive direction, the lower side of the second interface layer is the part body or additive substrate, and the upper side is the support structure; the second interface layer includes l An additive cladding layer with linear transition of components; wherein, from bottom to top, the first... k In the raw materials for each additive cladding layer, the mass fraction of aluminum alloy powder is: ×100%; of which k It is a positive integer, and 1 ≤ k ≤ l .

[0009] Furthermore, the support structure consists of multiple parallel rod-shaped components distributed in a grid-like or columnar manner in the area requiring support; the support structure is disposed between the additive substrate and the part body, or disposed within the structure of the part body, so as to maintain the shape of the part body consistent with the design shape.

[0010] Furthermore, the material of the additive substrate is the same as that of the part body; the average diameter of the raw material powder of the support structure, the part body, the first interface layer, and the second interface layer is 10μm to 60μm, and the thickness of a single additive cladding layer is 10μm to 60μm; the thickness of the additive substrate is 30mm to 50mm.

[0011] An easily removable support method based on laser selective melting gradient additive manufacturing includes the following steps: Step 1, Support Structure Design: Import the digital model of the part body into the additive support design software to generate the digital model of the support structure; import the digital models of the support structure and the part body into the laser selective melting simulation software, setting the support structure to aluminum alloy material and the part body to other metal materials besides aluminum alloy; use simulation software to simulate the additive manufacturing process, iterate repeatedly to obtain the digital model of the additive part that does not crack and whose deformation is within the design range, and slice the digital model of the additive part to obtain the sliced ​​digital model; Step 2, Gradient Additive Manufacturing: Selective Laser Melting Gradient Metal Printing Equipment is used. The equipment has a gradient powder supply system. The metal powder is uniformly mixed by the mixer and then transported to the powder spreading system to achieve a gradient continuous supply of powder. Gradient powder spreading is completed according to the slice digital model and the material information of each area. The laser completes the deposition of the cladding layer according to the slice digital model, so that the support structure, the part body, the first interface layer, and the second interface layer are formed as a whole. After the powder spreading and cladding of one layer are completed, the forming platform moves down one layer thickness to start the powder spreading and cladding process of the next layer until the additive part is formed. Step 3, removal of support structure and interface layer: Remove unmelted powder, and use wire cutting to separate the support structure, part body, first interface layer, second interface layer from the additive substrate; place the support structure, part body, first interface layer, and second interface layer as a whole in an alkaline etching solution, and etch them under ultrasonic vibration and thorough stirring to dissolve and remove the aluminum alloy support structure, first interface layer, and second interface layer. Step 4, Heat treatment of additive manufacturing parts: The part body is removed from the corrosion solution, cleaned and dried, and then subjected to overall heat treatment of the additive manufacturing parts according to the microstructure and performance requirements of the part body material. Step 5, Part post-processing: Fine grinding and polishing are performed on the surface of the part to remove the residual first interface layer. Non-destructive testing is then performed on the part to complete the part manufacturing process.

[0012] Furthermore, in step 4, when the part body is made of titanium alloy, the heat treatment is carried out in a vacuum furnace with a vacuum degree ≤ 6.67 × 10⁻⁶. - ²Pa, the pressure rise rate of vacuum furnace cooling is ≤0.4Pa / h, the heat treatment regime is to hold at 700℃ for 1h, cool with the furnace to 550℃ and then air cool to room temperature; when the part body is made of stainless steel, the heat treatment is carried out in a muffle furnace, the heat treatment regime is to hold at 800℃ for 1h and then air cool to room temperature.

[0013] Furthermore, in step 3, when the part body is made of titanium alloy, the alkaline corrosion solution is prepared by sodium hydroxide and deionized water, the solution temperature is 40°C, and the sodium hydroxide solution concentration is 120g / 100ml; when the part body is made of stainless steel, the alkaline corrosion solution is prepared by potassium hydroxide and deionized water, the solution temperature is 50°C, and the potassium hydroxide solution concentration is 170g / 100ml.

[0014] Furthermore, in step 2, when the aluminum alloy powder of the support structure is AlSi10Mg aluminum alloy and the part body is Ti6Al4V titanium alloy, the laser selective melting forming process parameters are laser power 250W, scanning speed 1200mm / s, and scanning spacing 0.1mm; when the aluminum alloy powder of the support structure is 2219 aluminum alloy and the part body is 304 stainless steel, the laser selective melting forming process parameters are laser power 300W, scanning speed 1500mm / s, and scanning spacing 0.15mm.

[0015] Furthermore, when the additive support design software described in step 1 slices the digital model containing the support structure and the part body, the slicing software sets different materials in different areas of the slice according to the digital model of the support structure, the part body, the first interface layer, and the second interface layer.

[0016] Compared with the prior art, the present invention has the following technical features: This invention employs a gradient laser selective melting manufacturing process to print the support structure as aluminum alloy and the part body as other metals. Utilizing the principle that aluminum alloy dissolves in alkaline solutions while other metals do not react, the support structure is selectively removed in the alkaline solution during support removal. This facilitates the removal of support structures in deep cavities and reduces the labor intensity for workers. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the additive manufacturing of the grille component in an embodiment of the present invention; Figure 2 This is a schematic diagram of the additive manufacturing process of the conduit parts in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the first interface layer; Figure 4 This is a schematic diagram of the structure of the second interface layer.

[0018] Explanation of reference numerals in the attached drawings: 1 Support structure, 2 Component body, 3 Additive substrate, 4 First interface layer, 5 Second interface layer. Detailed Implementation

[0019] This invention provides an easily removable support device and method based on laser selective melting gradient additive manufacturing. The support structure 1 is printed using aluminum alloy powder as raw material, and the part body 2 is printed using other metal powders. By utilizing the principle that aluminum alloy dissolves in alkaline solution while other metals do not react with alkali, the support structure 1 is selectively dissolved, making the support structure easy to remove without damaging the part.

[0020] See Figures 1 to 4 This invention provides an easily removable support device based on laser selective melting gradient additive manufacturing, comprising a support structure 1, a part body 2, an additive substrate 3, a first interface layer 4, and a second interface layer 5; with the additive direction as the positive direction, the support structure 1 and the part body 2 above it are connected by the first interface layer 4, as shown in the diagram. Figure 3 As shown; the support structure 1 and the underlying component body 2 or additive substrate 3 are transitioned through the second interface layer 5, and its structure is as follows. Figure 4 As shown. The support structure 1 consists of parallel rod-shaped components, distributed in a grid-like or columnar manner in the area requiring support; it is used to support the suspended parts of the structure during the additive manufacturing process of the part body 2. It can be set between the additive substrate 3 and the structure of the part body 2, or it can be set inside the structure of the part body 2, thereby keeping the shape of the part body 2 consistent with the design shape.

[0021] The supporting structure 1 is made of aluminum alloy powder, such as AlSi10Mg aluminum alloy powder or 2219 aluminum alloy powder. The part body 2 is made of metal powder other than aluminum alloy that does not react with alkaline solutions, such as titanium alloy powder, high-temperature alloy powder, or stainless steel powder. The additive substrate 3 is made of the same material as the part body 2, and the thickness of the additive substrate 3 is 30mm to 50mm.

[0022] See Figure 3 The raw material of the first interface layer 4 is a mixture of aluminum alloy powder from the printing support structure 1 and metal powder from the printing part body 2; with the additive direction as the positive direction, the lower side of the first interface layer 4 is the support structure 1, and the upper side is the part body 2; the first interface layer 4 includes j ( j An additive cladding layer with linear transitions of (positive integers) components; wherein, from the bottom to the top, the... i ( i It is a positive integer, and 1 ≤ i ≤ j In the raw materials for each additive cladding layer, the mass fraction of aluminum alloy powder is: ×100%.

[0023] The linear transition design of the aluminum alloy powder mass fraction decreasing layer by layer in the first interface layer 4 disperses the material property abrupt change that was originally concentrated on a single interface between the support structure 1 and the part body 2 into multiple cladding layers with different composition gradients. This avoids stress concentration at the interface due to the large difference in physical properties such as thermal expansion coefficient and elastic modulus between the two, reduces the risk of interface cracking during the forming process, and enhances the bonding strength of the dissimilar material interface between the support structure and the part body 2.

[0024] See Figure 4 The second interface layer 5 is made of a mixture of aluminum alloy powder from the printing support structure 1 and metal powder from the printed part body 2; with the additive direction as the positive direction, the lower side of the second interface layer 5 is the part body 2 or the additive substrate 3, and the upper side is the support structure 1; the second interface layer 5 includes l ( l An additive cladding layer with linear transitions of (positive integers) components; wherein, from the bottom to the top, the... k ( k It is a positive integer, and 1 ≤ k ≤ l In the raw materials for each additive cladding layer, the mass fraction of aluminum alloy powder is: ×100%.

[0025] The linear transition design of the aluminum alloy powder mass fraction increasing layer by layer in the second interface layer 5 also reduces the degree of abrupt change in material properties between the part body 2 or additive substrate 3 and the support structure 1 through continuous change of composition, reduces residual stress at the interface, and improves the bonding reliability of dissimilar material interfaces.

[0026] In this scheme, the average diameter of the raw material powder of the support structure 1, the part body 2, the transition layer 4, and the transition layer 5 is 10μm~60μm; the thickness of the additive cladding layer is 10μm~60μm.

[0027] Based on the above technical solutions, this invention provides an easily removable support method based on laser selective melting gradient additive manufacturing, comprising the following steps: Step 1, Design of Support Structure 1.

[0028] Import the digital model of part body 2 into the additive support design software, and generate the digital model of support structure 1 in the additive support design software; import the digital models of support structure 1 and part body 2 into laser selective melting simulation software, wherein support structure 1 is set to aluminum alloy material, and part body 2 is set to other metal materials other than aluminum alloy according to its design; use laser selective melting simulation software to simulate the additive process, iterate repeatedly, and obtain the digital model of additive part that does not crack and whose deformation is within the design range; use slicing software to slice the digital model of additive part to obtain the sliced ​​digital model.

[0029] Step 2: Laser selective melting gradient additive manufacturing of additive parts.

[0030] Selective laser melting gradient metal printing equipment is used to manufacture additive parts; the selective laser melting equipment has a gradient powder supply system, which can realize uniform powder mixing and material arrangement in the forming space as needed; an additive substrate 3 is installed in the equipment, and the equipment completes gradient powder laying according to the slice digital model obtained in S1 and the material information of each region. The laser completes the deposition of the cladding layer according to the slice digital model obtained in S1, so that the aluminum alloy material support structure 1, part body 2, first interface layer 4, and second interface layer 5 are integrally formed.

[0031] In one embodiment of the present invention, the laser selective melting forming process parameters are: laser power: 250W, scanning speed: 1200mm / s, and scanning spacing: 0.1mm. After one deposition layer completes powder spreading and cladding, the forming platform moves downward by one layer thickness to begin the powder spreading and cladding process for the next layer, until the additive part is formed.

[0032] Step 3: Remove support structure 1.

[0033] Unmelted powder was removed, and the support structure 1, part body 2, first interface layer 4, and second interface layer 5 were separated from the additive substrate 3 using wire cutting. The support structure 1, part body 2, first interface layer 4, and second interface layer 5 were then placed in an alkaline etching solution and etched under ultrasonic vibration and thorough stirring. The aluminum matrix in the aluminum alloy support structure 1 underwent the following chemical reaction in the alkaline solution, with the aluminum element in the aluminum alloy participating in the reaction in its elemental metallic form: 2Al + 2OH - +2H₂O→2AlO₂ - +3H2↑ The aluminum alloy support structure 1, the first interface layer 4, and the second interface layer 5 are dissolved, thereby removing the support structure 1 from the part body 2.

[0034] The alkaline corrosion solution is prepared by thoroughly mixing sodium hydroxide and deionized water at a temperature of 40°C, with a sodium hydroxide solution concentration of 120g / 100ml.

[0035] Alternatively, the alkaline corrosion solution is prepared by thoroughly mixing potassium hydroxide and deionized water at a temperature of 50°C, with a potassium hydroxide solution concentration of 170g / 100ml.

[0036] Step 4: Heat treatment of the additive manufacturing part.

[0037] After removing part body 2 from the corrosive solution, cleaning and drying are performed, and then the additively manufactured part undergoes overall heat treatment based on the microstructure and performance requirements of the material of part body 2. For example, when part body 2 is made of titanium alloy, the heat treatment is carried out in a vacuum furnace with a vacuum degree ≤ 6.67 × 10⁻⁶. - For parts with a vacuum furnace cooling capacity of ≤0.4Pa / h, the heat treatment regime is to hold at 700℃ for 1 hour, then cool in the furnace to 550℃ before air cooling to room temperature. Hot isostatic pressing may be necessary in some cases. When the body of part 2 is made of stainless steel, the heat treatment is carried out in a muffle furnace, and the heat treatment regime is to hold at 800℃ for 1 hour before air cooling to room temperature.

[0038] Step 5, post-processing of parts.

[0039] The surface of the part body 2 is subjected to final fine grinding and polishing to remove the residual first interface layer 4; the part body 2 is subjected to non-destructive testing to complete the manufacturing of the part body 2.

[0040] The final fine polishing process includes manual polishing, electrochemical polishing, abrasive flow polishing, etc.; the non-destructive testing includes geometric dimension testing, visual inspection, magnetic particle testing, fluorescence testing, X-ray testing, and ultrasonic testing, etc.

[0041] Example 1: like Figure 1 As shown, in this embodiment, the part body 2 is a grid part; the device consists of a support structure 1, a grid part, an additive substrate 3, a first interface layer 4, and a second interface layer 5; with the additive direction as the positive direction, the support structure 1 and the grid part above it are connected by the first interface layer 4, as shown. Figure 3 As shown; the support structure 1 and the underlying grid component or additive substrate 3 are transitioned through the second interface layer 5, such as... Figure 4 As shown.

[0042] Support structure 1 is made from AlSi10Mg aluminum alloy powder with an average powder diameter of 50 μm; the grid parts are made from Ti6Al4V titanium alloy powder with an average powder diameter of 50 μm. The additive substrate 3 is made of Ti6Al4V titanium alloy hot-rolled plate with a thickness of 43 mm. The alloy compositions of AlSi10Mg aluminum alloy powder, Ti6Al4V titanium alloy powder, and Ti6Al4V titanium alloy hot-rolled plate are shown in Tables 1 and 2.

[0043] Table 1. Composition of AlSi10Mg aluminum alloy powder

[0044] Table 2. Composition of Ti6Al4V titanium alloy powder and additive substrate

[0045] The first interface layer 4 is as follows Figure 3 The structure shown; with the additive manufacturing direction as the positive direction, the interface layer consists of 20 cladding layers, from the bottom to the top. i In the raw materials of each additive cladding layer ( i It is a positive integer, and 1 ≤ i ≤20), the mass fraction of aluminum alloy powder is ×100%. The second interface layer 5 is as follows: Figure 4 The structure shown. With the additive manufacturing direction as the positive direction, the interface layer consists of 10 cladding layers; from the bottom to the top... k In the raw materials of each additive cladding layer ( k It is a positive integer, and 1 ≤ k ≤10), the mass fraction of aluminum alloy powder is ×100%.

[0046] The method for removing the support structure in this embodiment is as follows: Step 1, Support structure design.

[0047] Import the digital model of the grille part into the Magics additive support design software to generate, as shown below. Figure 1 The digital model of support structure 1 is shown. The digital models of support structure 1 and the grid part are imported into the laser selective melting simulation software Simufact Additive, where support structure 1 is set to AlSi10Mg aluminum alloy and the grid part is set to Ti6Al4V titanium alloy. Simulation is performed using Simufact Additive software, iterating repeatedly to obtain an additive manufacturing model that does not crack and whose deformation is within the design range. In Magics software, the digital model containing support structure 1 and the grid part is sliced, with a slice thickness of 50μm. The slicing software sets different materials in different areas of the slice based on the digital models of support structure 1, grid part, first interface layer 4, and second interface layer 5.

[0048] Step 2: Laser selective melting gradient additive manufacturing of additive parts.

[0049] Selective laser melting gradient metal printing equipment is used to print an additive part consisting of a support structure 1, a grid part, an additive substrate 3, a first interface layer 4, and a second interface layer 5. This equipment features a gradient powder supply system, which uniformly mixes metal powder via a mixer and then delivers it to the powder spreading system, achieving a gradient and continuous supply of powder. The selective laser melting equipment completes gradient powder spreading based on the digital model of the slice obtained in step S1 and the material information of each region. The laser then completes the cladding of the deposited layers based on the digital model of the slice obtained in step S1, thus forming the support structure 1, grid part, first interface layer 4, and second interface layer 5 into a single unit. The selective laser melting forming process parameters are: laser power: 250W, scanning speed: 1200mm / s, scanning spacing: 0.1mm. After one layer of deposition is completed, the forming platform moves downwards by one layer thickness to begin the powder spreading and cladding process for the next layer, until the additive part is formed.

[0050] Step 3: Remove the supporting structure and interface layer.

[0051] Unmelted powder was removed, and the support structure 1, grid parts, first interface layer 4, and second interface layer 5 were separated from the additive substrate 3 using wire cutting. The support structure 1, grid parts, first interface layer 4, and second interface layer 5 were then placed in a NaOH alkaline etching solution and etched under ultrasonic vibration and thorough stirring to dissolve the support structure 1 and the first and second interface layers 4 and 5, allowing them to be removed from the grid parts. In this embodiment, the NaOH alkaline etching solution was prepared by mixing NaOH and deionized water at 40°C with a concentration of 120 g / 100 ml.

[0052] Step 4: Heat treatment of the additive manufacturing part.

[0053] The grid parts were removed from the corrosive solution, ultrasonically cleaned in a 75% ethanol solution, dried, and then subjected to heat treatment. The heat treatment was carried out in a vacuum furnace with a vacuum degree ≤6.67×10⁻⁶. -2 The pressure rise rate during vacuum furnace cooling is ≤0.4 Pa / h. The heat treatment regime is as follows: hold at 700℃ for 1 hour, cool in the furnace to 550℃, and then air-cool to room temperature. The grid parts also need to undergo hot isostatic pressing (HIP) treatment, which is performed at 160 MPa pressure and 1180℃ for 3 hours, followed by furnace cooling.

[0054] Step 5, post-processing of parts.

[0055] The outer surface of the grating parts is manually polished to remove the residual first interface layer 4. After geometric dimension inspection, visual inspection, magnetic particle inspection, fluorescence inspection, X-ray inspection and ultrasonic inspection, the grating parts meet the design requirements and no defects such as cracks, lack of fusion, pores, or inclusions are found.

[0056] Example 2: like Figure 2 As shown, in this embodiment, the component body 2 is a conduit component; the device consists of a support structure 1, a conduit component, an additive substrate 3, a first interface layer 4, and a second interface layer 5; with the additive direction as the positive direction, the support structure 1 and the conduit component above it are connected by the first interface layer 4, as shown. Figure 3 As shown; the support structure 1 and the underlying conduit component or additive substrate 3 are transitioned through the second interface layer 5, such as... Figure 4 As shown.

[0057] Support structure 1 is made from 2219 aluminum alloy powder with an average powder diameter of 55 μm. The conduit components are made from 304 stainless steel powder with an average powder diameter of 55 μm. The additive substrate 3 is made of 304 stainless steel hot-rolled plate with a thickness of 40 mm. The alloy compositions of the 2219 aluminum alloy powder, 304 stainless steel powder, and 304 stainless steel hot-rolled plate are shown in Tables 3 and 4.

[0058] Table 32219 Aluminum Alloy Powder Composition

[0059] Table 4. Composition of 304 stainless steel powder and additive substrate

[0060] The first interface layer 4 is as follows Figure 3 The structure shown. With the additive manufacturing direction as the positive direction, the interface layer consists of 30 cladding layers. From the bottom to the top... i In the raw materials of each additive cladding layer ( i It is a positive integer, and 1 ≤ i ≤30), the mass fraction of aluminum alloy powder is ×100%.

[0061] The second interface layer 5 is as follows Figure 4 The structure shown. With the additive manufacturing direction as the positive direction, the interface layer consists of 30 cladding layers. From the bottom to the top... k In the raw materials of each additive cladding layer ( k It is a positive integer, and 1 ≤ k ≤30), the mass fraction of aluminum alloy powder is ×100% The method for removing the support structure in this embodiment is as follows: Step 1, Support structure design.

[0062] Import the digital model of the conduit component into the Magics additive support design software to generate, for example... Figure 2The digital model of support structure 1 is shown. The digital models of support structure 1 and the conduit component are imported into the laser selective melting simulation software Simufact Additive, where support structure 1 is set to 2219 aluminum alloy and the conduit component to 304 stainless steel. Simulation is performed using SimufactAdditive software, iterating repeatedly to obtain an additive manufacturing model that does not crack and whose deformation is within the design range. In Magics software, the digital model containing support structure 1 and the conduit component is sliced, with a slice thickness of 50 μm. The slicing software sets different materials in different areas of the slice based on the digital models of support structure 1, conduit component, first interface layer 4, and second interface layer 5.

[0063] Step 2: Laser selective melting gradient additive manufacturing of additive parts.

[0064] Selective laser melting gradient metal printing equipment was used to print an additive part consisting of a support structure 1, a conduit component, an additive substrate 3, a first interface layer 4, and a second interface layer 5. This equipment features a gradient powder supply system, which uniformly mixes metal powder via a mixer and then delivers it to the powder spreading system, achieving a gradient and continuous supply of powder. The selective laser melting equipment completes gradient powder spreading based on the digital model of the slice obtained in step S1 and the material information of each region. The laser then completes the cladding of the deposited layers based on the digital model of the slice obtained in step S1, thus forming the support structure 1, the conduit component, the first interface layer 4, and the second interface layer 5 into a single unit. The selective laser melting forming process parameters are: laser power: 300W, scanning speed: 1500mm / s, scanning spacing: 0.15mm. After one layer of deposition is completed, the forming platform moves downwards by one layer thickness to begin the powder spreading and cladding process for the next layer, until the additive part is formed.

[0065] Step 3: Remove the supporting structure.

[0066] Unmelted powder was removed, and the support structure 1, conduit component, first interface layer 4, and second interface layer 5 were separated from the additive substrate 3 using wire cutting. The support structure 1, conduit component, first interface layer 4, and second interface layer 5 were then placed in a KOH alkaline etching solution and etched under ultrasonic vibration and thorough stirring to dissolve the support structure 1 and the first and second interface layers 4 and 5, allowing them to be removed from the conduit component. In this embodiment, the KOH alkaline etching solution was prepared by mixing KOH and deionized water at 50°C with a concentration of 170 g / 100 ml.

[0067] Step 4: Heat treatment of the additive manufacturing part.

[0068] The conduit components were removed from the corrosive solution, ultrasonically cleaned in a 75% ethanol solution, and then dried. They were then subjected to heat treatment in a muffle furnace. The heat treatment regime was as follows: holding at 800℃ for 1 hour, then air-cooling to room temperature.

[0069] Step 5, post-processing of parts.

[0070] The outer surface of the conduit component was manually finished with fine grinding and polishing, while the inner surface underwent abrasive flow polishing to remove the residual first interface layer 4. After geometric dimension inspection, visual inspection, magnetic particle inspection, fluorescence inspection, X-ray inspection, and ultrasonic inspection, the conduit component met the design requirements, and no defects such as cracks, lack of fusion, porosity, or inclusions were found.

[0071] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An easily removable support device based on laser selective melting gradient additive manufacturing, characterized in that, It includes a support structure (1), a part body (2), an additive substrate (3), a first interface layer (4), and a second interface layer (5); With the additive direction as the positive direction, the support structure (1) and the upper part body (2) are connected by a first interface layer (4); the support structure (1) and the lower part body (2) or additive substrate (3) are connected by a second interface layer (5). The support structure (1) is used to support the suspended part during the structural additive manufacturing process of the part body (2), and its raw material is aluminum alloy powder; the raw material of the part body (2) is metal powder other than aluminum alloy that does not react with alkaline solution. The raw material of the first interface layer (4) is a mixture of aluminum alloy powder of the printing support structure (1) and metal powder of the printing part body (2); the first interface layer (4) contains multiple additive cladding layers with linear transition of components, and the mass fraction of aluminum alloy powder in each additive cladding layer decreases layer by layer from the support structure (1) to the part body (2). The raw material of the second interface layer (5) is a mixture of aluminum alloy powder of the printing support structure (1) and metal powder of the printing part body (2); the second interface layer (5) contains multiple additive cladding layers with linear transition of components, and the mass fraction of aluminum alloy powder in each additive cladding layer increases layer by layer from the part body (2) or additive substrate (3) to the support structure (1).

2. The easily removable support device according to claim 1, characterized in that, With the additive manufacturing direction as the positive direction, the lower side of the first interface layer (4) is the support structure (1), and the upper side is the part body (2); the first interface layer (4) includes j An additive cladding layer with linear transition of components; wherein, from bottom to top, the first... i In the raw materials for each additive cladding layer, the mass fraction of aluminum alloy powder is: ×100%; of which i It is a positive integer, and 1 ≤ i ≤ j .

3. The easily removable support device according to claim 1, characterized in that, With the additive manufacturing direction as the positive direction, the lower side of the second interface layer (5) is the part body (2) or the additive substrate (3), and the upper side is the support structure (1); the second interface layer (5) includes l An additive cladding layer with linear transition of components; wherein, from bottom to top, the first... k In the raw materials for each additive cladding layer, the mass fraction of aluminum alloy powder is: ×100%; of which k It is a positive integer, and 1 ≤ k ≤ l .

4. The easily removable support device according to claim 1, characterized in that, The support structure (1) consists of multiple parallel rod-shaped components, distributed in a grid or column shape in the area requiring support; the support structure (1) is located between the additive substrate (3) and the part body (2), or inside the structure of the part body (2), so as to keep the shape of the part body (2) consistent with the design shape.

5. The easily removable support device according to claim 1, characterized in that, The material of the additive substrate (3) is the same as that of the part body (2); the average diameter of the raw material powder of the support structure (1), the part body (2), the first interface layer (4), and the second interface layer (5) is 10 μm to 60 μm, and the thickness of a single additive cladding layer is 10 μm to 60 μm; the thickness of the additive substrate (3) is 30 mm to 50 mm.

6. A method for easily removing supports based on laser selective melting gradient additive manufacturing, characterized in that, Using the easily removable support device as described in any one of claims 1 to 5 includes the following steps: Step 1, Support Structure Design: Import the digital model of the part body (2) into the additive support design software to generate the digital model of the support structure (1); import the digital models of the support structure (1) and the part body (2) into the laser selective melting simulation software, set the support structure (1) to aluminum alloy material, and set the part body (2) to other metal materials besides aluminum alloy; use simulation software to simulate the additive process, iterate repeatedly to obtain the digital model of the additive part that does not crack and whose deformation is within the design range, and slice the digital model of the additive part to obtain the slice digital model; Step 2, gradient additive manufacturing of additive parts: Selective laser melting gradient metal printing equipment is selected. The equipment has a gradient powder supply system. The metal powder is uniformly mixed by the mixer and then transported to the powder spreading system to realize the gradient continuous supply of powder in the powder spreading system. Gradient powder spreading is completed according to the slice digital model and the material information of each area. The laser completes the deposition of the cladding layer according to the slice digital model, so that the support structure (1), the part body (2), the first interface layer (4), and the second interface layer (5) are formed as a whole. After the powder spreading and cladding of one layer are completed, the forming platform moves down by one layer thickness and starts the powder spreading and cladding process of the next layer until the additive part is formed. Step 3, removal of support structure and interface layer: Remove unmelted powder, and use wire cutting to separate the support structure (1), part body (2), first interface layer (4), second interface layer (5) from the additive substrate (3); place the support structure (1), part body (2), first interface layer (4), and second interface layer (5) as a whole in an alkaline corrosion solution, and etch them under ultrasonic vibration and thorough stirring to dissolve and remove the aluminum alloy support structure (1), first interface layer (4), and second interface layer (5); Step 4, Heat treatment of additive parts: The part body (2) is taken out from the corrosion solution, cleaned and dried, and then the additive parts are subjected to overall heat treatment according to the microstructure and performance requirements of the material of the part body (2). Step 5, Part post-processing: Fine grinding and polishing are performed on the surface of the part body (2) to remove the residual first interface layer (4), and non-destructive testing is performed on the part body (2) to complete the manufacturing of the part body (2).

7. The method for easily removing supports according to claim 6, characterized in that, In Step 4, when the part body (2) is made of titanium alloy material, the heat treatment is performed in a vacuum furnace with a vacuum degree of ≤6.67x10 - Pa, a pressure rise rate of the vacuum furnace during emptying of the furnace is ≤0.4 Pa / h, a heat treatment schedule is to keep at 700°C for 1 h, and the furnace is cooled to 550°C, and then the part is taken out and air-cooled to room temperature; when the part body (2) is made of stainless steel material, the heat treatment is performed in a muffle furnace, and a heat treatment schedule is to keep at 800°C for 1 h, and then the part is taken out and air-cooled to room temperature.

8. The method for easily removing supports according to claim 6, characterized in that, In step 3, when the part body (2) is made of titanium alloy, the alkaline corrosion solution is prepared by sodium hydroxide and deionized water, the solution temperature is 40°C, and the sodium hydroxide solution concentration is 120g / 100ml; when the part body (2) is made of stainless steel, the alkaline corrosion solution is prepared by potassium hydroxide and deionized water, the solution temperature is 50°C, and the potassium hydroxide solution concentration is 170g / 100ml.

9. The method for easily removing supports according to claim 6, characterized in that, In step 2, when the aluminum alloy powder of the support structure (1) is AlSi10Mg aluminum alloy and the part body (2) is Ti6Al4V titanium alloy, the laser selective melting forming process parameters are laser power 250W, scanning speed 1200mm / s, and scanning spacing 0.1mm; when the aluminum alloy powder of the support structure (1) is 2219 aluminum alloy and the part body (2) is 304 stainless steel, the laser selective melting forming process parameters are laser power 300W, scanning speed 1500mm / s, and scanning spacing 0.15mm.

10. The method for easily removing supports according to claim 6, characterized in that, When the additive support design software described in step 1 slices the digital model containing the support structure (1) and the part body (2), the slicing software sets different materials in different areas of the slice according to the digital model of the support structure (1), the part body (2), the first interface layer (4), and the second interface layer (5).

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