A method of laser deposition additive manufacturing of overhanging structures and support assemblies

Abstract

The application discloses a method for laser deposition additive manufacturing of overhanging structure and a support assembly, and belongs to the technical field of additive manufacturing. The method comprises the following steps: firstly, depositing a part body below an overhanging starting surface, suspending, then fixing an oxide ceramic support body through a temporary mechanical fixing device, setting a metal sacrificial layer of the same base material system as the part body on the support body, continuing to deposit the overhanging structure, removing the fixing device after forming, and removing the sacrificial layer through mechanical processing to obtain a pure part. The support assembly comprises an oxide ceramic support body, a temporary mechanical fixing device and a metal sacrificial layer preform. The application solves the problems of difficult support removal, easy damage to the part and non-reusable support in the existing laser deposition forming of the overhanging structure, realizes self-falling of the support, non-chemical pollution and reusable support, significantly reduces the post-processing cost, and is suitable for laser deposition forming of titanium alloy, high-temperature alloy and the like.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to a method and support components for laser deposition additive manufacturing of overhanging structures. Background Technology

[0002] In laser-directed energy deposition additive manufacturing technology, manufacturing parts with overhanging or steeply inclined structures is a common technical challenge. For example, when manufacturing complex parts such as I-beams and cantilever structures, the overhanging parts are prone to collapse, warping, or even failure during the forming process due to the lack of lower support.

[0003] To solve this problem, the most common method is to use a metal material that is the same as or compatible with the part body to simultaneously print a solid support structure below the overhanging area. The support structure is connected to the part body by welding, and after forming, it needs to be removed by machining, wire cutting, or electrochemical dissolution. This post-processing is time-consuming and costly, and may damage the part surface or introduce residual stress, affecting part performance and yield; moreover, the support material is the same as the part, but it is ultimately removed, resulting in a waste of valuable metal materials.

[0004] Another strategy involves using a positioner to rotate the substrate or deposition head, transforming the original overhanging surface into a top- or side-facing orientation for deposition. This method can reduce or eliminate the need for supports. However, it places higher demands on the number of external axes of the equipment and positioning accuracy, and requires more complex path combination planning, resulting in additional costs and technical investment.

[0005] In recent years, some studies have explored using materials of different types from the metal part body (such as ceramics, ceramic precursors, or metals that do not wet the part) as supports. Theoretically, supports are easier to separate from the part due to the lack of metallurgical bonding or the formation of a weak bonding interface compared to supports made of the same material. For example, US Patent 11673289B2 discloses a method using different materials (metal or ceramic) to form a support structure, with a sacrificial interface region between the support and the part, followed by removal of the sacrificial layer through chemical or electrochemical dissolution. Furthermore, some literature reports the use of ceramic plates as direct physical supports for laser deposition.

[0006] However, existing heterogeneous material support solutions still have the following shortcomings: 1) Separation depends on chemical dissolution: The sacrificial layer still needs to be dissolved by chemical or electrochemical methods, which has a long process cycle, high waste liquid treatment cost, and is not suitable for material systems that are sensitive to chemical reagents; 2) Different sacrificial layer materials: The sacrificial layer in existing solutions is usually made of a different material than the part body. After dissolving, it may leave impurities or affect the purity of the part's chemical composition. 3) Supports are usually not reusable: Since the surface of the support may be contaminated or damaged during the separation process, most heterogeneous supports are for single use, which increases printing costs.

[0007] Therefore, there is an urgent need for a laser deposition additive manufacturing method that can reliably support the suspended structure, achieve rapid and non-destructive separation of the support, avoid contaminating the part itself, and allow for the reuse of the support material. Summary of the Invention

[0008] The purpose of this invention is to provide a method and support components for laser deposition additive manufacturing of overhanging structures, overcoming the defects of existing metal laser deposition additive manufacturing technology in forming overhanging structures, and solving the problems of traditional metal supports or heterogeneous supports that rely on chemical dissolution, which consume a lot of time and cost and may damage parts.

[0009] To achieve the above objectives, the present invention provides a method for laser deposition additive manufacturing of a cantilever structure, comprising the following steps: Step 1: Using laser deposition technology, deposit the part body on the substrate to a predetermined height below the starting surface of the overhanging structure to form the deposited portion; Step 2: Pause deposition and fix the prefabricated heterostructure to the deposited part or substrate using a temporary mechanical fixing assembly. The heterostructure is made of oxide ceramic material and its top surface shape matches the lower surface of the overhanging structure to be formed. Step 3: On the top surface of the heterogeneous support, a metal sacrificial layer belonging to the same matrix material system as the part body material is set, and the metal sacrificial layer has a preset thickness. Step 4: Continue to deposit the overhang structure on the metal sacrificial layer using laser deposition process until the entire part is completed, wherein the metal material of the overhang structure forms a metallurgical bond with the metal sacrificial layer; Step 5: Remove the temporary mechanical fixing components. Since there is no metallurgical bond between the heterogeneous support and the metal sacrificial layer, it can be detached as a whole by gravity or by applying external force. Step 6: Remove the metal sacrificial layer by machining to obtain the part body.

[0010] Preferably, the oxide ceramic material is selected from one of alumina, zirconium oxide, and mullite; the material of the part body is selected from steel, titanium alloy, or high-temperature alloy.

[0011] Preferably, the heterogeneous support is a prefabricated block, plate, or 3D-printed ceramic structure with a contoured support surface, based on the shape of the overhanging surface.

[0012] Preferably, the temporary mechanical fixing device includes one or more of the following: rigid struts, clamps, tape, and vacuum suction cups.

[0013] Preferably, the thickness of the metal sacrificial layer is related to the thermal input parameters of the laser deposition process in step 4. The thermal input parameters are configured to form a completely dense metallurgical bond between the metal sacrificial layer and the overhanging structure, while keeping the temperature of the top surface of the heterostructure below its melting point or softening point.

[0014] Preferably, the preset thickness of the metal sacrificial layer is 0.2mm to 2mm.

[0015] Preferably, in step 5, the external force is mechanical impact, ultrasonic vibration, or compressed gas purging.

[0016] Preferably, the heterogeneous support can be reused in another additive manufacturing process after surface cleaning following detachment.

[0017] Preferably, in step 6, after the metal sacrificial layer is removed, the lower surface of the overhanging structure of the part has the same chemical composition as the part body and is free of ceramic inclusions.

[0018] The present invention also provides a support assembly for laser deposition additive manufacturing, for implementing the above method, comprising: The heterogeneous support is made of oxide ceramic material and has a support surface that conforms to the lower surface of the suspended structure to be formed. Temporary mechanical fixing components are used to detachably fix a heterogeneous support to the substrate of a laser deposition equipment or to a deposited part portion; The metal sacrificial layer preform is a metal foil of the same material as the part body, which is placed on the support surface of the heterogeneous support.

[0019] Therefore, the method and support assembly for laser deposition additive manufacturing of overhanging structures of the present invention have the following beneficial effects: (1) Achieve non-destructive natural detachment of the support: Due to the incompatibility between the oxide ceramic support and the metal sacrificial layer, the metallurgical bond between the support and the part is fundamentally eliminated by physical contact alone. After the temporary fixation is removed, the support can fall off naturally by gravity or fall off completely by a slight tap. This avoids the risk of surface damage to the parts caused by wire cutting or milling of the traditional support of the same material, and also eliminates the need for chemical dissolution process, which greatly improves the efficiency of post-processing.

[0020] (2) Pure part body: The sacrificial layer is made of the same material as the part body, and its thickness is sufficient to protect the ceramic below from being melted or contaminated by the heat input of the molten pool. By using the sacrificial layer as a buffer, the sacrificial layer is finally removed by CNC machining. The part body material is below the overhanging surface, and there are no ceramic inclusions. This ensures that the final surface of the part and the body material are not affected by the support process, and meets the requirements of chemical composition and mechanical properties of high-performance parts.

[0021] (3) High forming quality: The sacrificial layer provides a flat and stable metal substrate, avoiding the first layer defects caused by the difference in thermal conductivity when depositing metal directly on ceramics, and the surface flatness of the overhang structure is good.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a laser deposition additive manufacturing overhang structure support component according to an embodiment of the present invention; Figure 2 This is a flowchart of a method for laser deposition additive manufacturing of a cantilever structure according to the present invention; Figure 3 This is a schematic diagram of the structure of the ceramic support in an embodiment of the present invention; Figure label: 1. Part to be formed; 2. Sacrificial layer; 3. Ceramic support; 4. Temporary mechanical fixing components. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0026] This invention proposes a method for using a heterogeneous material of a different material category than the part body as an auxiliary structure in a laser deposition support suspension structure, thereby achieving reliable printing of the suspension structure and enabling the support to detach automatically after printing.

[0027] Please see Figure 2 Specifically, it includes the following steps: Step 1: In laser deposition additive manufacturing, based on the shape characteristics and placement of the parts, the laser deposition process is used to first deposit the unsupported parts of the part body on the substrate until a predetermined height is reached below the starting surface of the overhanging structure, forming the deposited part.

[0028] Step 2: Pause deposition and fix the prefabricated heterogeneous support to the deposited portion or substrate using temporary mechanical fixing components to provide physical support for the suspended structure to be formed. For example, rigid struts can be used in conjunction with tape for auxiliary fixing and positioning to ensure its stability during the deposition process. The heterogeneous support is made of oxide ceramic material, and its top surface shape matches the lower surface of the suspended structure to be formed. This heterogeneous support does not undergo metallurgical bonding or reaction with the metal material to be deposited at high temperatures, fundamentally avoiding the formation of strong bonds.

[0029] Step 3: On the top surface of the heterogeneous support, a metal sacrificial layer belonging to the same matrix material system as the part body is set. The metal sacrificial layer has a preset thickness, providing a flat and stable metal substrate for the subsequent deposition of the metal layer. During overhanging additive manufacturing, the metal powder or wire melts together with the sacrificial layer to form a metallurgical structure. With the shielding of the sacrificial layer, the heat input of the molten pool is insufficient to melt the surface of the ceramic support or cause a significant interfacial reaction with it.

[0030] Step 4: Continue to deposit the overhang structure on the metal sacrificial layer using laser deposition process until the entire part is completed, in which the metal material of the overhang structure forms a metallurgical bond with the metal sacrificial layer.

[0031] Step 5: Remove the temporary mechanical fixing components. Since there is no metallurgical bond between the oxide ceramic, which serves as a heterogeneous support, and all the deposited metal layers (including the sacrificial layer), it is maintained only by physical contact. After removing the temporary fixing devices (such as struts or tape), the heterogeneous support can naturally and completely detach from the metal parts by gravity or by applying a little external force (such as a slight tap or vibration).

[0032] Step 6: After detachment, the lower surface of the overhanging structure will expose the sacrificial layer and transition layer. Subsequent CNC machining removes the metal sacrificial layer, yielding a part blank with chemical composition and microstructure that fully meet design requirements. The sacrificial layer acts as a process buffer layer, ensuring the purity of the part and protecting its surface during the detachment process.

[0033] In some embodiments of the present invention, the oxide ceramic material is selected from alumina, zirconium oxide, and mullite; the material of the part body is selected from steel, titanium alloy, or high-temperature alloy.

[0034] In some embodiments of the present invention, the heterogeneous support is a prefabricated block, plate, or 3D-printed ceramic structure with a contoured support surface, based on the shape of the overhanging surface.

[0035] In some embodiments of the present invention, the temporary mechanical fixing device includes one or more of the following: rigid struts, clamps, tape, and vacuum suction cups.

[0036] In some embodiments of the present invention, the thickness of the metal sacrificial layer is associated with the thermal input parameters of the laser deposition process in step 4, which are configured to form a completely dense metallurgical bond between the metal sacrificial layer and the overhanging structure, while keeping the temperature of the top surface of the heterostructure below its melting point or softening point.

[0037] In some embodiments of the present invention, the preset thickness of the metal sacrificial layer is 0.2 mm to 2 mm.

[0038] In some embodiments of the present invention, in step 5, the external force is mechanical impact, ultrasonic vibration, or compressed gas purging.

[0039] In some embodiments of the invention, the heterogeneous support can be reused in another additive manufacturing process after surface cleaning following detachment.

[0040] In some embodiments of the present invention, in step 6, after the metal sacrificial layer is removed, the lower surface of the overhanging structure of the part has the same chemical composition as the part body and is free of ceramic inclusions.

[0041] Example like Figure 1 , Figure 3 As shown, this embodiment uses laser deposition additive manufacturing to fabricate titanium alloy I-beam components. The titanium alloy I-beam component, as part 1 to be formed, has a long lower horizontal overhang. Its material is Ti-6Al-4V titanium alloy. The support material is a mullite ceramic plate, pre-formed according to the shape of the lower surface of the I-beam, and has a support surface consistent with the contour of the lower surface of the I-beam. The sacrificial layer 2 is made of pure titanium (TA2), which belongs to the same titanium-based material system as Ti-6Al-4V titanium alloy. The pure titanium sacrificial layer 2 is completely miscible with the Ti-6Al-4V molten pool during the deposition process, and the composition of the part body is not affected after subsequent CNC removal.

[0042] The specific manufacturing steps are as follows: Step 1: Deposit the web and upper flange of the I-beam on a titanium alloy substrate using laser deposition. The specific process parameters are: laser power 3400W, powder feed rate 8r / min, and moving speed 0.5m / min. First deposit the lower flange and web, and then pause when the upper flange is about 1.5mm above the overhang starting surface.

[0043] Step 2: The prefabricated mullite ceramic plate is used as the ceramic support 3. It is temporarily fixed and precisely positioned above the substrate by a temporary mechanical fixing assembly 4 consisting of two metal struts and high-temperature resistant tape. The top surface of the ceramic plate matches the lower surface of the lower flange of the I-beam to be formed, and a gap of about 0.5mm is maintained to accommodate the sacrificial layer.

[0044] Step 3: On the upper surface of the mullite ceramic plate, cover it with a pre-rolled 0.5mm thick pure titanium sheet as sacrificial layer 2. The pure titanium sheet is held in place by its own weight and the pressure from the deposition above.

[0045] Step 4: Continue depositing Ti-6Al-4V alloy on sacrificial layer 2 using the same laser deposition process until a full-height I-beam part is formed. During the deposition process, the pure titanium sheet forms a strong metallurgical bond with the Ti-6Al-4V deposited above, while the pure titanium sheet and the mullite ceramic only have physical contact and do not react.

[0046] Step 5: After molding is complete, remove the metal struts and high-temperature tape. Gently tap the side of the I-beam with a rubber mallet, and the mullite ceramic support plate will detach completely, with no metal adhering to the surface.

[0047] Step 6: Mount the part on a five-axis CNC machine tool and mill the lower surface of the I-beam to completely remove the pure titanium sacrificial layer and any potentially thin transition zones, exposing the pure Ti-6Al-4V matrix. The final part achieves the required dimensional accuracy and has no ceramic inclusions on its surface.

[0048] The I-beam cantilever structure fabricated in this embodiment is fully formed without collapse or warping. After removing the supports, the ceramic plate is wiped with alcohol, leaving a smooth surface without residue, and can be directly used for printing the same part in the next iteration. This embodiment verifies the feasibility of using a pre-formed metal sheet as a sacrificial layer, further reducing the process requirements for in-situ deposition of the sacrificial layer.

[0049] Comparative Example This comparative example, using a traditional support scheme, employs laser deposition additive manufacturing of a titanium alloy I-beam of the same specifications as in Example 1. This requires solid support for the entire lower part of the cantilever surface. Specifically: Support method: Using the same Ti-6Al-4V material as the part body, a solid support structure is printed below the overhanging surface. The support structure is connected to the part body by metallurgical bonding (welding).

[0050] To ensure that the overhang does not collapse during the deposition process, the support structure must cover the entire lower flange projection area and be designed as a continuous and dense solid with a thickness that matches the overhang height.

[0051] After the part is printed, wire cutting is used to initially separate the support from the part body, and then five-axis CNC milling is used to finish the lower surface to remove the residual support.

[0052] Testing revealed that the weight of the materials used in the comparative example increased by 84 kg, and the material utilization rate decreased to 6% compared to 53.1% in the example.

[0053] Compared to the embodiments of the present invention, traditional solutions have extremely low material utilization, enormous support weight, and significantly increased post-processing time and costs. This fully demonstrates that the present invention represents a significant technological advancement in saving materials, simplifying post-processing, and reducing manufacturing costs.

[0054] Therefore, this invention provides a method and support assembly for laser deposition additive manufacturing of overhanging structures. Utilizing the incompatibility between ceramics and metals, it fundamentally eliminates the metallurgical bond between the support and the part, allowing for easy removal of the support after forming. This avoids complex and time-consuming mechanical or chemical removal processes, significantly improving post-processing efficiency. By setting a sacrificial layer as a buffer and placing it within the final CNC machining removal range, it ensures that the final surface and body material of the part are not affected by the support process, guaranteeing the purity of the part's chemical composition and mechanical properties. Using temporary mechanical fixing (such as struts or tape) to install the prefabricated ceramic support eliminates the need for designing complex special fixtures or positioners, reducing manufacturing costs and preparation time, and improving process flexibility. If the detached ceramic support is undamaged, it can be used for the remanufacturing of the same or similar parts after simple cleaning.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for laser deposition additive manufacturing of a cantilever structure, characterized in that, Includes the following steps: Step 1: Using laser deposition technology, deposit the part body on the substrate to a predetermined height below the starting surface of the overhanging structure to form the deposited portion; Step 2: Pause deposition and fix the prefabricated heterostructure to the deposited part or substrate using a temporary mechanical fixing assembly. The heterostructure is made of oxide ceramic material and its top surface shape matches the lower surface of the overhanging structure to be formed. Step 3: On the top surface of the heterogeneous support, a metal sacrificial layer belonging to the same matrix material system as the part body material is set, and the metal sacrificial layer has a preset thickness. Step 4: Continue to deposit the overhang structure on the metal sacrificial layer using laser deposition process until the entire part is completed, wherein the metal material of the overhang structure forms a metallurgical bond with the metal sacrificial layer; Step 5: Remove the temporary mechanical fixing components. Since there is no metallurgical bond between the heterogeneous support and the metal sacrificial layer, it can be detached as a whole by gravity or by applying external force. Step 6: Remove the metal sacrificial layer by machining to obtain the part body.

2. The method for laser deposition additive manufacturing of a cantilever structure according to claim 1, characterized in that: The oxide ceramic material is selected from one of alumina, zirconium oxide, and mullite; the material of the part body is selected from steel, titanium alloy, or high-temperature alloy.

3. The method for laser deposition additive manufacturing of a cantilever structure according to claim 2, characterized in that: Heterogeneous supports are prefabricated blocks, plates, or 3D-printed ceramic structures with contoured support surfaces, based on the shape of the overhanging surface.

4. The method for laser deposition additive manufacturing of a cantilever structure according to claim 3, characterized in that: Temporary mechanical fixing devices include one or more of the following: rigid struts, clamps, tape, and vacuum suction cups.

5. The method for laser deposition additive manufacturing of a cantilever structure according to claim 4, characterized in that: The thickness of the metal sacrificial layer is related to the thermal input parameters of the laser deposition process in step 4. The thermal input parameters are configured to form a completely dense metallurgical bond between the metal sacrificial layer and the overhanging structure, while keeping the temperature of the top surface of the heterostructure below its melting point or softening point.

6. The method for laser deposition additive manufacturing of a cantilever structure according to claim 5, characterized in that: The preset thickness of the metal sacrificial layer is 0.2mm to 2mm.

7. The method for laser deposition additive manufacturing of a cantilever structure according to claim 6, characterized in that: In step 5, the external force is mechanical impact, ultrasonic vibration, or compressed gas purging.

8. A support assembly for laser deposition additive manufacturing, used to implement the method according to any one of claims 1-7, characterized in that, include: The heterogeneous support is made of oxide ceramic material and has a support surface that conforms to the lower surface of the suspended structure to be formed. Temporary mechanical fixing components are used to detachably fix a heterogeneous support to the substrate of a laser deposition equipment or to a deposited part portion; The metal sacrificial layer preform is a metal foil of the same material as the part body, which is placed on the support surface of the heterogeneous support.

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