Additive manufacturing of a hollowed-out metal component and method of making the same

Abstract

This invention relates to an additive manufacturing method for hollow metal components, comprising the following steps: printing raw materials into hollow structure parts; the raw materials consist of metal particles and a thermoplastic polymer binder; heating the hollow structure parts to a set temperature to remove the thermoplastic polymer binder, resulting in a hollow structure part after binder removal; the set temperature is determined by thermogravimetric analysis of the hollow structure parts; the heating rate V to the set temperature and the wall thickness t of the hollow structure parts must satisfy the following relationship: 0.1 mm·℃ / min ≤ V×t ≤ 0.4 mm·℃ / min; 0.1 mm ≤ t ≤ 1 mm, where V is in ℃ / min; sintering the hollow structure parts after binder removal to obtain the additively manufactured hollow metal component. This invention is mainly used to ensure the quality of the hollow metal components while eliminating the need for chemical reagents to remove the binder during additive manufacturing.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and in particular to an additively manufactured hollow metal component and its preparation method. Background Technology

[0002] Additive manufacturing (AM) is a technology that creates parts by adding materials layer by layer. It enables the fabrication of complex shapes with computer assistance, which is difficult to achieve with traditional manufacturing techniques. The additive manufacturing process does not rely on molds, reducing many conventional machining steps and expensive tooling. This technology has been designed for manufacturing metal components, including powder bed fusing (PBF) and direct energy deposition (DED). However, the equipment used in these technologies is expensive and subject to strict safety regulations due to the risks associated with the use of powders and hazardous energy sources such as lasers and electron beams. Furthermore, the localized melting and rapid solidification of the PBF method leads to high-temperature-induced residual stresses, requiring rigid supports and post-processing.

[0003] In recent years, Bound Metal Deposition (BMD) has emerged as an extrusion technology based on powder-filled thermoplastic media. As a novel additive manufacturing technique for metal components, BMD offers a new solution to the problem of high costs associated with manufacturing complex metal components by producing high-quality metal parts at a lower cost. Furthermore, BMD technology eliminates the adverse effects of thermal cycling by avoiding repeated melting and sintering at high energy sources. Simultaneously, BMD allows for component printing at the polymer's printing temperature. Therefore, BMD technology has garnered increasing attention.

[0004] However, a crucial step in BMD technology is the removal of the binder. Currently, almost all binder removal methods rely on chemical reagents, which are often toxic or hazardous, and the process is complex and costly. Therefore, developing a safe, easy-to-operate, and low-cost method for removing binders in the fabrication of metal components using BMD technology is of great significance. Summary of the Invention

[0005] In view of this, the present invention provides an additive manufacturing hollow metal component and a method for preparing the same. The main purpose is to ensure the quality of the hollow metal component while eliminating the need for chemical reagents to remove the adhesive during the preparation of the additive manufacturing hollow metal component.

[0006] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0007] On one hand, embodiments of the present invention provide a method for preparing an additively manufactured hollow metal component, which includes the following steps:

[0008] Printing steps: Print the raw material into a hollow structure; the raw material consists of metal particles and thermoplastic polymer binder;

[0009] Adhesive removal step: In an environment with an oxygen content below 2 ppm, the hollow structure printed part is heated to a set temperature to remove the thermoplastic polymer adhesive in the hollow structure part, resulting in a hollow structure part after adhesive removal; wherein, the set temperature is determined by thermogravimetric analysis of the hollow structure printed part; wherein, the heating rate V to the set temperature and the wall thickness t of the hollow structure printed part must satisfy the following relationship: 0.1 mm·℃ / min ≤ V×t ≤ 0.4 mm·℃ / min; wherein, 0.1 mm ≤ t ≤ 1 mm, and the unit of V is ℃ / min;

[0010] Sintering process: The hollow structure after removing the binder is sintered to obtain an additively manufactured hollow metal component.

[0011] Preferably, in the printing step: the content of thermoplastic polymer binder in the raw material is 8-14 wt%, preferably 10-12 wt%; the content of metal particles in the raw material is 86-92 wt%; preferably, the raw material also contains additives; more preferably, the content of the additives is 0-1.5 wt%.

[0012] Preferably, the raw material is filament; and / or the metal particles are stainless steel particles, preferably 316L stainless steel particles; the thermoplastic polymer binder is polyoxymethylene (POM).

[0013] Preferably, in the printing step: the raw material is heated and then sprayed onto the printing platform through a nozzle to print a hollow structure part; preferably, the temperature of the nozzle is 1-1.4 times the melting temperature of the thermoplastic polymer binder; preferably, the temperature of the nozzle is 230-250℃; preferably, the temperature of the printing platform is 80-120℃, more preferably 100-120℃; it should be noted that the printing platform is the substrate that carries the printed part; preferably, the present invention uses a glass platform, on which polyimide tape is adhered, and the printed part is printed onto the polyimide tape for easy removal from the substrate. The printing speed refers to the speed at which the nozzle moves. Preferably, the printing speed is 5-30 mm / s, more preferably 10-20 mm / s. Here, the printing speed refers to the speed at which the nozzle moves.

[0014] Preferably, in the printing step: the perforated structure printed part has a through-hole structure, and all walls of the perforated structure printed part are in contact with air. It should be noted that: when removing the adhesive solely through heating without using chemical reagents, adhesive removal is difficult. After being heated and forming vapor, sufficient space is needed for release to prevent obstructed release and defects such as blistering and cracking in the component (therefore, it is necessary to ensure that all walls of the perforated structure printed part are in contact with air).

[0015] Preferably, in the adhesive removal step, the heating rate V to the set temperature and the wall thickness t of the hollow structure printed part need to satisfy the following relationship: 0.3 mm·℃ / min ≤ V×t ≤ 0.4 mm·℃ / min; where 0.3 mm ≤ t ≤ 0.6 mm.

[0016] Preferably, in the adhesive removal step, the environment with an oxygen content of less than 2 ppm includes a vacuum environment and an inert gas environment.

[0017] Preferably, in the adhesive removal step: the hollow structure printed part is heated to a set temperature at a heating rate V, held at the temperature for a set time, and then cooled (with furnace cooling); preferably, the set temperature is 380-420℃; preferably, the set time is 0-3h, more preferably 0.5-3h, and even more preferably 1-2h; preferably, the heating rate V is 0.2-3℃ / min, more preferably 0.5-1℃ / min.

[0018] Preferably, in the sintering process: the hollowed-out structural component after removing the binder is heated to a first sintering temperature at a first heating rate, held at that temperature for a first time, then heated to a second sintering temperature at a second heating rate, held at that temperature for a second time, and then cooled (cooled in the furnace); preferably, the first heating rate is 3-8℃ / min, more preferably 4-6℃ / min; the second heating rate is 3-8℃ / min, more preferably 4-6℃ / min; preferably, the first sintering temperature is 500-700℃, more preferably 600-700℃; the second sintering temperature is 1370-1380℃; preferably, the first time is 0.5-2h, more preferably 1-1.5h; preferably, the second time is 2-3h.

[0019] Compared with the prior art, the additive manufacturing hollow metal component and its preparation method of the present invention have at least the following beneficial effects:

[0020] The additive manufacturing method for hollow metal components provided in this invention proposes for the first time a step of removing the binder by heating without using chemical reagents. Specifically, in an environment with an oxygen content of less than 2 ppm, the hollow structure printed part is heated to a set temperature to remove the thermoplastic polymer binder in the hollow structure part, resulting in a hollow structure part after binder removal. The set temperature is determined by thermogravimetric analysis of the hollow structure printed part. The heating rate V to the set temperature and the wall thickness t of the hollow structure printed part must satisfy the following relationship: 0.1 mm·℃ / min ≤ V×t ≤ 0.4 mm·℃ / min; where 0.1 mm ≤ t ≤ 1 mm, and the unit of V is ℃ / min. Here, through extensive research, this invention has identified a narrow range of relationships between the wall thickness *t* of the embossed structure and the heating rate *v*. Specifically, when the heating rate *v* and wall thickness *t* satisfy the following relationship: 0.1 mm·℃ / min ≤ *V* × *t* ≤ 0.4 mm·℃ / min (0.1 mm ≤ *t* ≤ 1 mm), the binder can be successfully removed by heating without producing defects. Preferably, the relationship between the heating rate *v* and wall thickness *t* is 0.3 mm·℃ / min ≤ *V* × *t* ≤ 0.4 mm·℃ / min (0.3 mm ≤ *t* ≤ 0.6 mm). The inventors have discovered that when removing the binder by heating, as long as the heating rate is controlled as described above, blistering and cracking of the structural component can be avoided, and harmful phases will not be formed, thus not affecting the formation of dense metal after sintering. In summary, this invention, when preparing additively manufactured embossed metal components, eliminates the need for chemical reagents to remove the binder while ensuring the quality of the embossed metal components (defect-free and with excellent density).

[0021] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is the thermogravimetric curve of the hollow structure printed part;

[0023] Figure 2 Figure (a) is a physical image of the hollow structure printed part prepared in Example 1, and Figure (b) is a physical image of the hollow metal component prepared in Example 1.

[0024] Figure 3 This is a SEM image of the hollowed-out metal component prepared in Example 1;

[0025] Figure 4 This is an EBSD analysis image of the hollowed-out metal component prepared in Example 1;

[0026] Figure 5This is a SEM image of the hollow structure after removing the adhesive in Example 4;

[0027] Figure 6 This is a SEM image of the hollow structure component prepared in Comparative Example 3 after removing the adhesive. Detailed Implementation

[0028] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0029] For BMD (Binder Deposition Modeling) technology, current methods for removing binder typically combine chemical reagents with heating. The role of the chemical reagents is to create micropores within the component, providing channels for the release of remaining binder during heating. Without chemical reagents, the component lacks these channels, and the binder can only be removed layer by layer. If the heating rate is too fast, the binder decomposes too quickly within the component, generating excessive vapor. Without these micropore channels, the vapor accumulates, causing blistering and cracking. Conversely, if the heating rate is too slow, the binder decomposes too slowly, potentially resulting in incomplete removal. This leads to residual carbon in the component, which forms harmful phases during subsequent sintering, affecting the formation of dense metal after sintering and severely reducing mechanical properties.

[0030] To address the limitations of current adhesive removal methods in BMD (Body Modulation) technology, this invention achieves adhesive removal from components without the use of chemical reagents. Removing adhesive solely through heating is more environmentally friendly, efficient, safer, easier to operate, and lower in cost than using chemical reagents, but this method is generally considered impossible or extremely difficult.

[0031] To remove the binder by heating, this invention, through extensive research, identified a narrow range of relationships between the wall thickness *t* of the etched structure printed part and the heating rate *v*. Specifically, when the heating rate *v* and wall thickness *t* satisfy the following relationship: 0.1 mm·℃ / min ≤ *V*×t ≤ 0.4 mm·℃ / min (0.1 mm ≤ *t* ≤ 1 mm), the binder can be successfully removed by heating without producing defects, thus successfully solving this problem. Preferably, the relationship between the heating rate *v* and wall thickness *t* is 0.3 mm·℃ / min ≤ *V*×t ≤ 0.4 mm·℃ / min (0.3 mm ≤ *t* ≤ 0.6 mm). The inventors discovered that when removing the binder by heating, as long as the heating rate is controlled as described above, blistering and cracking of the structure can be avoided, and harmful phases will not be formed, thus not affecting the formation of dense metal after sintering.

[0032] The specific solution of the present invention is as follows:

[0033] On one hand, the present invention provides a method for preparing an additively manufactured hollow metal component, which includes the following steps:

[0034] Printing steps: Print the raw material into a hollow structure; the raw material consists of metal particles and thermoplastic polymer binder.

[0035] In this step: the raw material is printing filament (here, it is not limited to filament, it can also be rod, etc.). The main components of the raw material include metal particles (preferably stainless steel particles, more preferably 316L stainless steel particles) and thermoplastic polymer binder (preferably polyoxymethylene POM). The content of the thermoplastic polymer binder is 8-14 wt%, preferably 10-12 wt%. Preferably, the raw material also includes additives (e.g., surfactants and plasticizers), with a content of 8-9 wt%.

[0036] In this step: the hollow structure printed part has a through hole structure with a wall thickness of 0.1-1mm, and all the thin walls in the hollow structure printed part are in contact with air.

[0037] In this step: the raw material is heated and then sprayed onto the printing platform through a nozzle to print a hollow structure. The printing parameters are as follows: the nozzle temperature is 1-1.4 times the melt temperature of the thermoplastic polymer binder, preferably 230-250℃; the printing platform temperature is 80-120℃, preferably 100-120℃; and the printing speed is 5-30mm / s, preferably 10-20mm / s.

[0038] Adhesive removal step: In an environment with an oxygen content of less than 2 ppm, the hollow structure printed part is heated to a set temperature to remove the thermoplastic polymer adhesive in the hollow structure part, resulting in a hollow structure part after adhesive removal; wherein, the set temperature is determined by thermogravimetric analysis of the hollow structure printed part; wherein, the heating rate V to the set temperature and the wall thickness t of the hollow structure printed part must satisfy the following relationship: 0.1 mm·℃ / min ≤ V×t ≤ 0.4 mm·℃ / min; wherein, 0.1 mm ≤ t ≤ 1 mm, and the unit of V is ℃ / min.

[0039] Preferably, the heating rate V to the set temperature and the wall thickness t of the hollow structure printed part need to satisfy the following relationship: 0.3 mm·℃ / min≤V×t≤0.4 mm·℃ / min; where 0.3 mm≤t≤0.6 mm.

[0040] In this step: the set temperature is determined based on the thermogravimetric curve of the printed part, where the thermogravimetric curve is shown in [reference needed]. Figure 1 Specifically, thermogravimetric analysis can record the change in sample mass with temperature. The thermogravimetric curve can show at what temperature the sample begins to lose weight and at what temperature the weight loss ends, and the set temperature can be determined based on this. Figure 1 The peak value in the thermogravimetric curve indicates the point of fastest weight loss, and based on this, the set temperature is determined to be 380-420℃.

[0041] Specifically, in an environment with an oxygen content of less than 2 ppm (including vacuum and Ar environments), the heating process is as follows: the temperature is raised to 380℃-420℃ (preferably 380℃-400℃) at a heating rate of 0.2-3℃ / min (preferably 0.5-1℃ / min), held at that temperature for 0.5-3h (preferably 1-2h), and then cooled.

[0042] Sintering process: The hollow structure after removing the binder is sintered to obtain an additively manufactured hollow metal component.

[0043] The purpose of the sintering process is to heat the component to a temperature slightly below the melting point of the metal, so that the metal particles gradually combine to form a dense metal.

[0044] In this step: the hollowed-out structural component after removing the adhesive is heated to 500-700℃ at a heating rate of 3-8℃ / min and held at that temperature for 0.5-2 hours. Then, the temperature is further increased to 1370℃-1380℃ at a rate of 3-8℃ / min and held for 2-3 hours. Preferably, the hollowed-out structural component after removing the adhesive is heated to 600-700℃ at a heating rate of 4-6℃ / min and held for 1-1.5 hours. Then, the temperature is further increased to 1370-1380℃ at a rate of 4-6℃ / min and held for 2-3 hours before cooling.

[0045] Regarding the above-described solution of the present invention, it should be noted that:

[0046] (1) Removing the adhesive by heating is more environmentally friendly than using chemical reagents: chemical reagents are usually toxic, harmful to operators, and environmentally unfriendly, and need to be recycled.

[0047] (2) Heating to remove the adhesive is more efficient than using chemical reagents: the time required to remove the adhesive by chemical reagents is about 24-60 hours, while the time required to remove the adhesive by heating in this invention is no more than 7 hours, which greatly reduces the time to remove the adhesive and improves manufacturing efficiency.

[0048] (3) Removing the binder by heating is safer and easier to operate than using chemical reagents: When using chemical reagents to remove polymers, the slow chemical reaction poses a safety risk, while heating has a low safety risk and is simple to operate.

[0049] (4) The equipment for removing adhesives by heating is simple, avoids the use of chemical reagents, and is less expensive.

[0050] (5) Thin-walled hollow metal components are an important part of automotive anti-collision systems and protective motion equipment. In this invention, thin-walled hollow metal components were successfully manufactured using BMD technology without the use of chemical reagents to remove the adhesive. This solves the problem that chemical reagents could not be avoided in the past, overcomes the difficulty of removing the adhesive by heating alone, and provides a new approach to the manufacture of thin-walled hollow metal components.

[0051] The present invention will be further illustrated below through specific experimental examples:

[0052] Example 1

[0053] This invention provides a method for additive manufacturing of hollow metal components, comprising the following steps:

[0054] (1) Printing steps: Print the raw material into a hollow structure print.

[0055] The raw material is printing filament. The printing filament consists of 316L stainless steel particles, polyoxymethylene (POM), and additives; the POM content is 10 wt%, the metal particles content is 89 wt%, and the additive content is 1 wt%.

[0056] The printing parameters are as follows: nozzle temperature is 240℃, printing platform temperature is 110℃, and printing speed is 15mm / s.

[0057] In this embodiment, the wall thickness of the hollow structure printed part is 0.4 mm, and the structure is shown in [see details]. Figure 2As shown in Figure (a).

[0058] (2) Adhesive removal step: Determine the heating temperature based on the thermogravimetric curve of the cutout structure printed part (according to...) Figure 1 (The peak value of the curve is determined). The specific heating process is as follows: In an Ar environment, the temperature is raised to 380℃ at a heating rate of 1℃ / min, and held for 1 hour before being cooled with the furnace to obtain the hollow structure after removing the binder.

[0059] Here, the heating rate V and wall thickness t in this step satisfy the following relationship: 0.1 mm·℃ / min ≤ V×t ≤ 0.4 mm·℃ / min.

[0060] (3) Sintering process: The hollow structure after removing the adhesive is heated to 600°C at a heating rate of 5°C / min and held for 1 hour. Then, it is heated to 1380°C at the same rate of 5°C / min and held for 3 hours. After cooling, the hollow metal component is obtained.

[0061] Here, please refer to the physical image of the hollowed-out metal component prepared in this embodiment. Figure 2 As shown in Figure (b) of the document.

[0062] The hollowed-out metal component prepared in this embodiment was observed by SEM, and its SEM image is shown below. Figure 3 .from Figure 3 It can be seen that the particle surface is smooth, the binder has been removed, and the component does not have defects such as blistering and cracking.

[0063] In addition, the microstructure of the hollow metal component prepared in this embodiment contains an austenitic phase with twins, indicating that a dense metal component is formed after sintering, with a relative density greater than 95%.

[0064] EBSD analysis was performed on the hollowed-out metal component prepared in this embodiment. See [link to EBSD analysis]. Figure 4 As shown, this thin-walled hollow structure has an energy absorption effect and can be used as an energy absorption component.

[0065] Example 2

[0066] This invention provides a method for additive manufacturing of hollow metal components. The main difference between this embodiment and Embodiment 1 is that the printing speed is different. The printing speed of Embodiment 2 is 5 mm / s, while the other steps are the same as those of Embodiment 1.

[0067] The printing effect of this embodiment is good, and the adhesive is removed in this embodiment, so no defects such as blistering and cracking are generated. After the final sintering treatment, a dense thin-walled hollow metal component is formed.

[0068] Example 3

[0069] This invention provides a method for additive manufacturing of hollow metal components. The main difference between this embodiment and embodiment 1 is that the printing speed is different. The printing speed of embodiment 3 is 30 mm / s, while the other steps are the same as those of embodiment 1.

[0070] (1) Printing steps: Print the raw material into a hollow structure; wherein the raw material consists of metal particles and thermoplastic polymer binder.

[0071] The printing effect of this embodiment is good, and the adhesive is removed in this embodiment, so no defects such as blistering and cracking are generated. After the final sintering treatment, a dense thin-walled hollow metal component is formed.

[0072] Example 4

[0073] This invention provides a method for additive manufacturing of hollow metal components, which differs from Example 1 in that: in the adhesive removal step, after heating to 380°C, the temperature is not maintained at that temperature. The other steps are the same as in Example 1.

[0074] The adhesive removal step in this embodiment is as follows: In an Ar environment, the temperature is raised to 380°C at a rate of 1°C / min, without holding, and directly cooled to room temperature in the furnace to obtain the hollowed-out structural part after adhesive removal. Here, the heating rate V and wall thickness t in this step satisfy the following relationship: 0.1 mm·°C / min ≤ V×t ≤ 0.4 mm·°C / min.

[0075] SEM observation was performed on the hollowed-out structural component after the adhesive was removed, such as... Figure 5 As shown, a small amount of binder residue remained on the surface of the metal particles, but most of the binder was removed, and the component did not exhibit defects such as blistering or cracking. In this embodiment, a dense, thin-walled, perforated metal component was formed after final sintering.

[0076] Example 5

[0077] This invention provides a method for additive manufacturing of hollow metal components, which differs from Example 1 in that: in the adhesive removal step, the temperature is raised to 380°C and held for 1 hour, then the temperature is raised further to 420°C, but not held at that temperature. The other steps are the same as in Example 1.

[0078] The adhesive removal step in this embodiment is as follows: In an Ar environment, the temperature is raised to 380°C at a heating rate of 1°C / min, held at this temperature for h, and then further raised to 420°C. Without holding, the temperature is directly cooled to room temperature in the furnace to obtain the hollowed-out structural part after the adhesive has been removed. Here, the heating rate V and the wall thickness t in this step satisfy the following relationship: 0.1 mm·°C / min ≤ V×t ≤ 0.4 mm·°C / min.

[0079] In this embodiment, the adhesive is removed through a bonding process without causing defects such as blistering or cracking. The final sintering process results in a dense, thin-walled, perforated metal component.

[0080] Example 6

[0081] This invention provides a method for additive manufacturing of hollow metal components. The main difference from Embodiment 1 is that the wall thickness of the printed hollow structure is 0.1 mm, and the heating rate in the adhesive removal step is 3 °C / min (the heating rate V and the wall thickness t satisfy the following relationship: 0.1 mm·°C / min ≤ V×t ≤ 0.4 mm·°C / min). All other steps are completely the same.

[0082] In this embodiment, the adhesive is removed through a bonding process without causing defects such as blistering or cracking. The final sintering process results in a dense, thin-walled, perforated metal component.

[0083] Comparative Example 1

[0084] This comparative example prepares an additively manufactured hollow metal component, which differs from Example 1 in that the printing speed is 40 mm / s. However, Comparative Example 1 has the following problems: due to the faster printing speed, the printing stripes are uneven, multiple breaks occur, and the thin-walled hollow component cannot be completely formed.

[0085] Comparative Example 2

[0086] This comparative example prepares an additively manufactured hollow metal component, which differs from Example 1 in that the wall thickness of the hollow structure printed part is 0.8 mm, while the other steps are completely the same.

[0087] In the adhesive removal step of Comparative Example 2, the heating rate did not meet the requirement of 0.1 mm·℃ / min≤V×t≤0.4 mm·℃ / min, which caused blistering and cracking in the component after heating. As a result, a defect-free thin-walled hollow component could not be manufactured after sintering.

[0088] Comparative Example 3

[0089] Comparative Example 3 provides a method for additive manufacturing of hollow metal components, which differs from Example 1 in that the temperature is raised to 340°C in the adhesive removal step, without heat preservation. All other steps are exactly the same.

[0090] SEM images of the hollowed-out structural component after adhesive removal are shown below. Figure 6 As shown, a large amount of binder is present. Due to the large amount of binder, a dense metal component cannot be formed after sintering.

[0091] Comparative Example 4

[0092] Comparative Example 4 provides a method for additive manufacturing of hollow metal components, which differs from Example 1 in that the temperature is raised to 450°C in the adhesive removal step, without heat preservation. All other steps are exactly the same.

[0093] In this comparative example, the hollow structure component after removing the adhesive exhibited blistering and cracking defects, and after sintering, it could not form a defect-free thin-walled hollow metal component.

[0094] In summary, the additive manufacturing method for hollow metal components provided in this embodiment of the invention can ensure the quality of the hollow metal components without using chemical reagents to remove the adhesive.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an additively manufactured hollow metal component, characterized in that, It comprises the following steps: The printing step: printing the raw material into a hollow structure printed part; wherein the composition of the raw material comprises metal particles and a thermoplastic polymer binder; wherein the raw material is heated and then sprayed from the nozzle onto the printing platform to form a hollow structure printed part; wherein the printing speed is 5-30mm / s; The binder removal step: heating the hollow structure printed part to a set temperature in an environment with an oxygen content of less than 2ppm to remove the thermoplastic polymer binder in the hollow structure part, obtaining a hollow structure part after removing the binder; wherein the set temperature is determined by thermogravimetric analysis of the hollow structure printed part; wherein the heating rate V to the set temperature and the wall thickness t of the hollow structure printed part satisfy the following relationship: 0.1mm·℃ / min≤V×t≤0.4mm·℃ / min; wherein 0.1mm≤t≤1mm, and the unit of V is ℃ / min; wherein the hollow structure printed part is heated to the set temperature at a heating rate V, and cooled after holding for a set time; wherein the set temperature is 380-420℃; The sintering treatment step: sintering the hollow structure part after removing the binder to obtain an additive manufacturing hollow metal component.

2. The method of claim 1, wherein, In the printing step: The content of the thermoplastic polymer binder in the raw material is 8-14wt%; the content of the metal particles in the raw material is 86-92wt%.

3. The method of claim 2, wherein, In the printing step: the content of the thermoplastic polymer binder in the raw material is 10-12wt%.

4. The method according to claim 1, wherein In the printing step: the raw material also contains an additive; wherein the content of the additive is 0-1.5wt%.

5. The method of claim 1, wherein, The raw material is a wire material.

6. The method of claim 1, wherein, The metal particles are stainless steel particles; the thermoplastic polymer binder is polyoxymethylene POM.

7. The method of claim 6, wherein, The metal particles are 316L stainless steel particles.

8. The method of claim 1, wherein, In the printing step: the temperature of the nozzle is 1-1.4 times the melting temperature of the thermoplastic polymer binder.

9. The method of claim 8, wherein, In the printing step: the temperature of the nozzle is 230-250℃.

10. The method of claim 1, wherein, In the printing step: the temperature of the printing platform is 80-120℃.

11. The method of claim 10, wherein, In the printing step: the temperature of the printing platform is 100-120℃.

12. The method of claim 1, wherein, In the printing step: The printing speed is 10-20mm / s.

13. The method of claim 1, wherein, In the printing step: The hollow structure printed part is a through-hole structure, and all the walls of the hollow structure printed part are in contact with air.

14. The method of claim 1, wherein, In the binder removal step: The heating rate V to the set temperature and the wall thickness t of the hollow structure printed part satisfy the following relationship: 0.3mm·℃ / min≤V×t≤0.4mm·℃ / min; wherein 0.3mm≤t≤0.6mm.

15. The method of claim 1, wherein, In the binder removal step: The environment with an oxygen content of less than 2ppm includes a vacuum environment, an inert gas environment.

16. The method of claim 1, wherein, In the binder removal step: the set time is 0-3h.

17. The method of claim 16, wherein, In the binder removal step: the set time is 0.5-3h.

18. The method of claim 17, wherein, In the binder removal step: the set time is 1-2h.

19. The method of claim 1, wherein, In the binder removal step: the temperature increasing rate V is 0.2-3℃ / min.

20. The method of claim 19, wherein, In the binder removal step: the temperature increasing rate V is 0.5-1℃ / min.

21. The method of claim 1, wherein, In the sintering treatment step: the binder-removed hollow structure is heated to a first sintering temperature at a first temperature increasing rate, kept for a first time, then heated to a second sintering temperature at a second temperature increasing rate, kept for a second time, and then cooled.

22. The method of claim 21, wherein, the first temperature increasing rate is 3-8℃ / min; the second temperature increasing rate is 3-8℃ / min.

23. The method of claim 22, wherein, the first temperature increasing rate is 4-6℃ / min; the second temperature increasing rate is 4-6℃ / min.

24. The method of claim 21, wherein, the first sintering temperature is 500-700℃; the second sintering temperature is 1370-1380℃.

25. The method of claim 24, wherein, the first sintering temperature is 600-700℃.

26. The method of claim 21, wherein, the first time is 0.5-2h.

27. The method of claim 26, wherein, the first time is 1-1.5h.

28. The method of claim 21, wherein: the second time is 2-3h.

29. An additively manufactured open-structured metal component, characterized in that, The additive manufacturing hollow metal member is prepared by the method of any one of claims 1-28.

30. The additively manufactured lattice metal structure of claim 29, wherein, The additive manufacturing hollow metal member is a stainless steel member.

31. The additively manufactured lattice metal structure of claim 30, wherein, The additive manufacturing hollow metal member contains a twinned austenite phase.

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