CN117680698A - Hollowed-out metal component manufactured by additive and preparation method thereof - Google Patents
Hollowed-out metal component manufactured by additive and preparation method thereof Download PDFInfo
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- CN117680698A CN117680698A CN202311664254.9A CN202311664254A CN117680698A CN 117680698 A CN117680698 A CN 117680698A CN 202311664254 A CN202311664254 A CN 202311664254A CN 117680698 A CN117680698 A CN 117680698A
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Abstract
The invention relates to a hollowed-out metal component for additive manufacturing and a preparation method thereof, wherein the method comprises the following steps: printing the raw materials into a printing piece with a hollow structure; the components of the raw materials comprise metal particles and thermoplastic polymer binders; heating the hollow structure printing piece to a set temperature to remove the thermoplastic polymer binder in the hollow structural piece, so as to obtain the hollow structural piece from which the binder is removed; the set temperature is determined by performing thermogravimetric analysis on the hollow-out structure printing piece; the temperature rising rate V for heating to the set temperature and the wall thickness t of the printed part with the hollow structure are required to meet the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute; t is more than or equal to 0.1mm and less than or equal to 1mm, and V is in a unit of ℃/min; and sintering the hollow structural member after the binder is removed to obtain the hollow metal structural member for additive manufacturing. The method is mainly used for preparing the hollowed-out metal component during additive manufacturing, and the quality of the hollowed-out metal component is ensured while the binder is not required to be removed by adopting a chemical reagent.
Description
Technical Field
The invention relates to the technical field of additive manufacturing, in particular to a hollowed-out metal component for additive manufacturing and a preparation method thereof.
Background
Additive manufacturing (additive manufacturing, AM) is a technique for manufacturing parts by adding material layer by layer, enabling structures with complex shapes to be manufactured with the aid of a computer, which is difficult to achieve in conventional manufacturing techniques. The additive manufacturing process is mold independent, reducing many conventional processing steps and expensive tooling. This technique has been designed for manufacturing metal components, including powder bed fusion (powder bed fusing, PBF) and direct energy deposition (direct energy deposition, DED). However, the equipment used for these techniques is expensive and subject to strict safety regulations due to the risk of using powders and dangerous energy sources such as lasers and electron beams. In addition, the localized melting and rapid solidification of the PBF process results in high thermally induced residual stresses requiring rigid support and post-processing.
In recent years, bond metal deposition (Bound Metal Deposition, BMD) has been an extrusion technique based on powder filled thermoplastic media. BMD, a new technology for manufacturing metal components by additive, can produce high quality metal components at a low cost, and provides a new solution to the problem that the cost for manufacturing metal components with complex structures is generally high. In addition, BMD techniques do not require repeated melting and sintering at high energy sources, thereby eliminating the adverse effects of thermal cycling. At the same time, BMD prints the component at the printing temperature of the polymer. BMD technology has gained increasing attention.
However, an important element in BMD technology is binder removal. At present, the binder removal mode almost depends on chemical reagents, but the chemical reagents are usually toxic or dangerous, the operation of the process is complex, and the cost is high. In summary, it is important to develop a safe, easy to operate and low cost way to remove the binder for the process of preparing the metal component using BMD technology.
Disclosure of Invention
In view of the above, the present invention provides a hollowed-out metal component for additive manufacturing and a method for preparing the same, which mainly aims to ensure the quality of the hollowed-out metal component without adopting chemical reagents to remove binders when preparing the hollowed-out metal component for additive manufacturing.
In order to achieve the above purpose, the present invention mainly provides the following technical solutions:
in one aspect, an embodiment of the present invention provides a method for preparing a hollowed-out metal member for additive manufacturing, including the steps of:
and (3) printing: printing the raw materials into a printing piece with a hollow structure; wherein the components of the raw materials comprise metal particles and a thermoplastic polymer binder;
and (3) removing the binder: heating the hollowed-out structural printing piece to a set temperature in an environment with the oxygen content lower than 2ppm so as to remove the thermoplastic polymer binder in the hollowed-out structural piece and obtain the hollowed-out structural piece from which the binder is removed; the set temperature is determined by performing thermogravimetric analysis on the hollowed-out structure printing piece; the heating rate V for heating to the set temperature and the wall thickness t of the hollow-out structure printing piece are required to meet the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.1mm and less than or equal to 1mm, and V is in a unit of ℃/min;
sintering treatment: and sintering the hollow structural member after the binder is removed to obtain the hollow metal member for additive manufacturing.
Preferably, in the printing step: the thermoplastic polymer binder content in the raw materials is 8-14wt%, preferably 10-12wt%; the content of metal particles in the raw materials is 86-92wt%; preferably, the raw materials also contain additives; further preferably, the content of the additive is 0 to 1.5wt%.
Preferably, the raw material is a wire; and/or the metal particles are stainless steel particles, preferably 316L stainless steel particles; the thermoplastic polymer binder is polyoxymethylene POM.
Preferably, in the printing step: heating the raw materials, spraying the raw materials onto a printing platform through a nozzle, and printing to form a printing piece with a hollow structure; preferably, the temperature of the nozzle is 1 to 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 ℃, preferably 100-120 ℃; what should be stated here is: the printing platform is a substrate for bearing printing pieces; preferably, the invention uses a glass platform to which a polyimide tape is adhered, and the printed article is printed onto the polyimide tape to facilitate removal of the printed article from the substrate. The printing speed refers to the speed at which the nozzles move. Preferably, the printing speed is 5 to 30mm/s, more preferably 10 to 20mm/s. The printing speed here is the speed at which the nozzles move.
Preferably, in the printing step: the hollow-out structure printing piece is of a through hole structure, and all walls of the hollow-out structure printing piece are in contact with air. Here, it should be noted that: in the case of removing the binder by heating without using a chemical agent, it is difficult to remove the binder, and a sufficient release space is required after it is heated to form steam to prevent defects such as foaming and cracking of the member due to release inhibition (thus, it is required to ensure that all walls of the printed member of the hollow structure are in contact with air).
Preferably, in the binder removal step: the temperature rising rate V for heating to the set temperature and the wall thickness t of the hollow-out structure printing piece are required to meet the following relation: v x t is less than or equal to 0.3mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.3mm and less than or equal to 0.6mm.
Preferably, in the binder removal step: the environment with the oxygen content lower than 2ppm comprises a vacuum environment and an inert gas environment.
Preferably, in the binder removal step: heating the hollow-out structure printing piece to a set temperature at a heating rate V, preserving heat for a set time, and cooling (cooling with a furnace); preferably, the set temperature is 380-420 ℃; preferably, the setting time is 0 to 3 hours, preferably 0.5 to 3 hours, further preferably 1 to 2 hours; preferably, the temperature rising rate V is 0.2-3 ℃/min, preferably 0.5-1 ℃/min.
Preferably, in the sintering treatment step: heating the hollow structural member after the binder is removed to a first sintering temperature at a first heating rate, preserving heat for a first time, then continuously heating to a second sintering temperature at a second heating rate, preserving heat for a second time, and cooling (cooling along with a furnace); preferably, the first heating rate is 3-8 ℃/min, preferably 4-6 ℃/min; the second heating rate is 3-8 ℃/min, preferably 4-6 ℃/min; preferably, the first sintering temperature is 500-700 ℃, preferably 600-700 ℃; the second sintering temperature is 1370-1380 ℃; preferably, the first time is 0.5-2 hours, preferably 1-1.5 hours; preferably, the second time is 2-3 hours.
Compared with the prior art, the hollow metal component for additive manufacturing and the preparation method thereof have at least the following beneficial effects:
the preparation method of the hollowed-out metal component for additive manufacturing provided by the embodiment of the invention is provided for the first time: the method comprises the steps of removing a binder without using a chemical reagent by adopting a heating mode, specifically, heating a printing piece with a hollow structure to a set temperature in an environment with oxygen content lower than 2ppm so as to remove a thermoplastic polymer binder in the hollow structural piece, and obtaining the hollow structural piece after the binder is removed; the set temperature is determined by performing thermogravimetric analysis on the hollowed-out structure printing piece; the heating rate V for heating to the set temperature and the wall thickness t of the hollow-out structure printing piece are required to meet the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.1mm and less than or equal to 1mm, and V is in a unit of ℃/min. In the invention, a narrow relation range between the wall thickness t and the heating temperature rising rate V of the hollow-out structure printing piece is found through a large amount of researches, namely when the temperature rising rate V and the wall thickness t meet the following relation of 0.1mm DEG C/min not more than V multiplied by t not more than 0.4mm DEG C/min (0.1 mm not more than t not more than 1 mm), the binder can be successfully removed through a heating method without generating defects. Wherein, the relation between the temperature rising rate V and the wall thickness t is preferably 0.3mm DEG C/min which is less than or equal to V x t which is less than or equal to 0.4mm DEG C/min (0.3 mm which is less than or equal to t which is less than or equal to 0.6 mm). Here, the inventors found that: when the binder is removed by heating, foaming and cracking of the structural member can be avoided by controlling the heating rate, and the formation of dense metal after sintering can not be influenced. In conclusion, when the additive manufacturing hollowed-out metal component is manufactured, the method does not need to adopt chemical reagents to remove the binder, and ensures the quality (without defects and with excellent compactness) of the hollowed-out metal component.
The foregoing description is only an overview of the present invention, and is intended to provide a better understanding of the present invention, as it is embodied in the following description, with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
FIG. 1 is a thermogravimetric graph of a printed part of hollow structure;
fig. 2 is a diagram (a) showing a printed matter of the hollow structure prepared in example 1, and (b) showing a diagram of a hollow metal member prepared in example 1;
FIG. 3 is an SEM image of a hollowed out metal part made in example 1;
FIG. 4 is an EBSD analysis chart of the hollowed out metal component prepared in example 1;
FIG. 5 is an SEM image of the hollow structure of example 4 after removing the binder;
fig. 6 is an SEM image of the debindered hollow out structural member prepared in comparative example 3.
Detailed Description
In order to further describe the technical means and effects adopted for achieving the preset aim of the invention, the following detailed description refers to the specific implementation, structure, characteristics and effects according to the application of the invention 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, the particular features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.
For BMD technology, the current way to remove the binder is typically a combination of chemicals and heat. The chemical agent functions to form microscopic voids within the member, which are channels for the remaining binder to release during heating. When no chemical reagent is used, the interior of the component is provided with pore channels, the adhesive can only be removed in a layer-by-layer release mode, if the temperature rising rate is too high, the adhesive is decomposed too fast in the interior of the component to form more steam, and at the moment, the component is provided with microscopic pore channels, and the steam is accumulated in the interior of the component to force the component to generate foaming and cracks. When the rate of temperature rise is too slow, the binder is decomposed too slowly, and there may be cases where binder removal is incomplete, which may result in carbon residue in the component and formation of deleterious phases during subsequent sintering, affecting the formation of dense metals after sintering, and severely degrading mechanical properties.
In view of the limitations of the current methods of removing binders in BMD technology, the present invention achieves binder removal from components without the use of chemicals. Removal of the binder by heating alone is more environmentally friendly, more efficient, safer, more manageable and less costly than the use of chemical agents, but this approach is generally considered impossible or very difficult.
In order to remove the binder by heating, a narrow relation range between the wall thickness t and the heating temperature rising rate V of the hollow-out structure printing piece is found through a large number of researches, namely when the temperature rising rate V and the wall thickness t meet the following relation, V x t is less than or equal to 0.1 mm/min is less than or equal to 0.4 mm/min (t is less than or equal to 0.1mm is less than or equal to 1 mm), the binder can be successfully removed by heating without generating defects, and the problem is successfully solved. Wherein, the relation between the temperature rising rate V and the wall thickness t is preferably 0.3mm DEG C/min which is less than or equal to V x t which is less than or equal to 0.4mm DEG C/min (0.3 mm which is less than or equal to t which is less than or equal to 0.6 mm). Here, the inventors found that: when the binder is removed by heating, structural foaming and cracking can be avoided by controlling the heating rate, and the formation of a dense metal after sintering can not be influenced by forming a harmful phase.
The specific scheme of the invention is as follows:
in one aspect, the preparation method of the hollowed-out metal component for additive manufacturing provided by the embodiment of the invention comprises the following steps:
and (3) printing: printing the raw materials into a printing piece with a hollow structure; wherein the components of the raw materials comprise metal particles and a thermoplastic polymer binder.
In this step: the raw material is a printing wire (here, not limited to a wire, but may be a bar or the like). The components of the feedstock mainly comprise metal particles (preferably stainless steel particles, more preferably 316L stainless steel particles) and a thermoplastic polymer binder (preferably polyoxymethylene POM). Wherein the content of the thermoplastic polymer binder is 8-14wt%, preferably 10-12wt%. Preferably, the raw materials further include additives (e.g., surfactants, plasticizers, etc.) in an amount of 8 to 9wt%.
In this step: the hollow-out structure printing piece is of a through hole structure, the wall thickness is 0.1-1mm, and all the thin walls in the hollow-out structure printing piece are in contact with air.
In this step: and heating the raw materials, spraying the raw materials onto a printing platform through a nozzle, and printing to form a printing piece with a hollow structure. The printing parameter range is as follows: the nozzle temperature is 1 to 1.4 times the melting temperature of the thermoplastic polymer binder, preferably the nozzle temperature is 230 to 250 ℃; the temperature of the printing platform is 80-120 ℃, preferably 100-120 ℃; the printing speed is 5-30mm/s, preferably 10-20mm/s.
And (3) removing the binder: heating the hollowed-out structural printing piece to a set temperature in an environment with the oxygen content lower than 2ppm so as to remove the thermoplastic polymer binder in the hollowed-out structural piece and obtain the hollowed-out structural piece from which the binder is removed; the set temperature is determined by performing thermogravimetric analysis on the hollowed-out structure printing piece; the heating rate V for heating to the set temperature and the wall thickness t of the hollow-out structure printing piece are required to meet the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.1mm and less than or equal to 1mm, and V is in a unit of ℃/min.
Preferably, the temperature rising rate V heated to the set temperature and the wall thickness t of the printed part with the hollow structure need to satisfy the following relationship: v x t is less than or equal to 0.3mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.3mm and less than or equal to 0.6mm.
In this step: the set temperature is determined from a thermal weight curve of the print, wherein the thermal weight curve is shown in fig. 1. Specifically, the thermogravimetric analysis can record the change of the mass of the sample along with the temperature, and the thermogravimetric curve can observe at what temperature point the sample starts to lose weight and at what temperature point the loss of weight is finished, and the set temperature is formulated according to the change. The peak in the thermogravimetric curve in fig. 1 is the point of the fastest loss of weight, from which the set temperature is determined to be 380-420 ℃.
Specifically, in an environment with the oxygen content lower than 2ppm (including a vacuum environment and an Ar environment), the specific process of heating is as follows: raising the temperature to 380-420 ℃ at a heating rate of 0.2-3 ℃/min (preferably 0.5-1 ℃/min), keeping the temperature for 0.5-3h (preferably 1-2 h) and cooling.
Sintering treatment: and sintering the hollow structural member after the binder is removed to obtain the hollow metal member for additive manufacturing.
The purpose of the sintering treatment step is: the component is heated to a temperature slightly below the melting point of the metal, so that the metal particles gradually combine to finally form a dense metal.
In this step: heating the hollow structural member after removing the binder to 500-700 ℃ at a heating rate of 3-8 ℃/min, preserving heat for 0.5-2h, then continuously heating to 1370-1380 ℃ at a heating rate of 3-8 ℃/min, and preserving heat for 2-3h. Preferably, the hollow structural member after the binder is removed is heated to 600-700 ℃ at the heating rate of 4-6 ℃/min, is kept for 1-1.5h, is continuously heated to 1370-1380 ℃ at the heating rate of 4-6 ℃/min, is kept for 2-3h, and is cooled.
Regarding the above-described aspects of the present invention, it should be noted that:
(1) Removal of the binder by heating is more environmentally friendly than the way in which chemical agents are used: chemical reagents are generally toxic, are not friendly to operators, and are environmentally unfriendly and need to be recycled.
(2) Removal of the binder by heating is more efficient than using chemical agents: the time for removing the binder by the chemical reagent is about 24-60 hours, and the time for heating to remove the binder is not more than 7 hours, so that the time for removing the binder is greatly reduced, and the manufacturing efficiency is improved.
(3) Removal of the binder by heating is safer and easier to handle than using chemical agents: when the chemical reagent is used for removing the polymer, the slow chemical reaction has safety risk, and the heating mode has low safety risk and is simple to operate.
(4) The device for heating and removing the binder is simple, avoids using chemical reagents, and has lower cost.
(5) The thin-wall hollowed-out metal component is an important component of an automobile anti-collision system and protective sports equipment. According to the invention, the thin-wall hollow metal component is successfully manufactured by a BMD technology without using a chemical reagent to remove the binder, the problem that the chemical reagent cannot be used before is solved, the difficulty of removing the binder only by heating is broken through, and a new thought is provided for manufacturing the thin-wall hollow metal component.
The invention is further illustrated below by means of specific experimental examples:
example 1
The embodiment of the invention provides a method for manufacturing a hollowed-out metal component by additive, which comprises the following steps:
(1) And (3) printing: printing the raw materials into a printing piece with a hollow structure.
Wherein the raw material is printing silk material. The printing wire comprises 316L stainless steel particles, polyoxymethylene (POM) and additives; wherein the content of POM is 10wt%, the content of metal particles in the raw material is 89wt%, and the content of the additive is 1wt%.
Wherein, the printing parameters are as follows: the nozzle temperature was 240 ℃, the printing platform temperature was 110 ℃, and the printing speed was 15mm/s.
The thickness of the hollow-out structure printing piece prepared in the embodiment is 0.4mm, and the structure is shown in a (a) diagram in fig. 2.
(2) And (3) removing the binder: the heating temperature is determined according to the thermal weight curve of the printed piece with the hollow structure (determined according to the curve peak value of fig. 1). The specific heating process is as follows: in Ar environment, heating to 380 ℃ at a heating rate of 1 ℃/min, preserving heat for 1h, and cooling with a furnace to obtain the hollow structural member after removing the binder.
Here, the heating rate V and the wall thickness t in this step satisfy the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute.
(3) Sintering treatment: and heating the hollow structural member after the binder is removed to 600 ℃ at a heating rate of 5 ℃/min, preserving heat for 1h, continuously heating to 1380 ℃ at the same rate of 5 ℃/min, preserving heat for 3h, and cooling to obtain the hollow metal structural member.
Here, a physical diagram of the hollowed-out metal member prepared in this embodiment is shown in fig. 2 (b).
SEM observation is carried out on the hollowed-out metal component prepared in the embodiment, and an SEM image of the hollowed-out metal component is shown in FIG. 3. As can be seen from fig. 3: the surface of the particles is smooth, the binder is removed, and the member has no defects such as foaming and cracking.
In addition, the microstructure of the hollowed-out metal component prepared in the embodiment forms an austenite phase containing twin crystals, which indicates that a compact metal component is formed after sintering, and the relative density of the compact metal component is more than 95%.
EBSD analysis is carried out on the hollowed-out metal component prepared by the embodiment, and the thin-wall hollowed-out structure has an energy absorption effect and can be used as an energy absorption component as shown in FIG. 4.
Example 2
The embodiment of the invention provides a method for manufacturing a hollowed-out metal component by additive, which is mainly different from embodiment 1 in that: the printing speed was different, and the printing speed of example 2 was 5mm/s, and the other steps were the same as in example 1.
The printing effect of the embodiment is good, the binder is removed, the defects such as foaming and cracking are not generated, and the compact thin-wall hollowed-out metal component is formed after final sintering treatment.
Example 3
The embodiment of the invention provides a method for manufacturing a hollowed-out metal component by additive, which is mainly different from embodiment 1 in that: the printing speed was varied, and the printing speed of example 3 was 30mm/s, and the other steps were identical to those of example 1.
(1) And (3) printing: printing the raw materials into a printing piece with a hollow structure; wherein the components of the raw materials comprise metal particles and a thermoplastic polymer binder.
The printing effect of the embodiment is good, the binder is removed, the defects such as foaming and cracking are not generated, and the compact thin-wall hollowed-out metal component is formed after final sintering treatment.
Example 4
The embodiment of the invention provides a method for manufacturing a hollowed-out metal component in an additive manner, which is different from embodiment 1 in that: in the binder removal step, after the temperature was raised to 380 ℃, no heat preservation was performed at that temperature. Other steps were consistent with example 1.
The binder removal step of this embodiment is as follows: in Ar environment, the temperature is raised to 380 ℃ at the heating rate of 1 ℃/min, the heat is not preserved, and the hollow structural member is directly cooled to room temperature along with a furnace, so that the hollow structural member after the binder is removed is obtained. Here, the heating rate V and the wall thickness t in this step satisfy the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute.
SEM observation is carried out on the hollow structural member after the binder is removed, as shown in fig. 5, a small amount of binder remains on the surface of the metal particles, most of the binder is removed, and the structural member has no defects such as foaming, cracking and the like. The embodiment finally forms a compact thin-wall hollowed-out metal component after sintering treatment.
Example 5
The embodiment of the invention provides a method for manufacturing a hollowed-out metal component in an additive manner, which is different from embodiment 1 in that: in the binder removal step, the temperature is raised to 380 ℃ and then kept for 1h, and then the temperature is continuously raised to 420 ℃ without keeping the temperature. Other steps were consistent with example 1.
The binder removal step of this embodiment is as follows: in Ar environment, heating to 380 ℃ at a heating rate of 1 ℃/min, keeping the temperature for h, continuously heating to 420 ℃, and directly cooling to room temperature along with a furnace without keeping the temperature, thus obtaining the hollow structural member after removing the binder. Here, the heating rate V and the wall thickness t in this step satisfy the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute.
In this embodiment, the binder is removed by the binder removal step, and defects such as foaming and cracking are not generated. And finally, forming a compact thin-wall hollowed-out metal component after sintering treatment.
Example 6
The embodiment of the invention provides a method for manufacturing a hollowed-out metal component by additive, which is mainly different from embodiment 1 in that: the wall thickness of the hollow-out structure printing piece is 0.1mm, and the heating rate in the step of removing the binder is 3 ℃/min (the heating rate V and the wall thickness t meet the following relational expression that V multiplied by t is less than or equal to 0.1mm and less than or equal to 0.4 mm). The other steps are completely identical.
In this embodiment, the binder is removed by the binder removal step, and defects such as foaming and cracking are not generated. And finally, forming a compact thin-wall hollowed-out metal component after sintering treatment.
Comparative example 1
This comparative example produces an additive manufactured hollowed-out metal part that differs from example 1 in that: the printing speed was 40mm/s. However, comparative example 1 had the following cases: because the printing speed is higher, the printing stripes are uneven, a plurality of positions are broken, and the thin-wall hollowed-out member cannot be integrally formed.
Comparative example 2
This comparative example produces an additive manufactured hollowed-out metal part that differs from example 1 in that: the wall thickness of the hollow-out structure printing piece is 0.8mm, and other steps are completely consistent.
In the binder removal step of comparative example 2, since the temperature rising rate does not satisfy: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute, so that the heated member generates foaming and cracks, and a defect-free thin-wall hollowed-out member cannot be manufactured after sintering treatment.
Comparative example 3
Comparative example 3 provides a method of additive manufacturing of hollowed-out metal components, differing from example 1 in that: in the binder removal step, the temperature was raised to 340℃without maintaining the temperature. The other steps are completely identical.
SEM observation is carried out on the hollowed-out structural part after the binder is removed, and an SEM image is shown in FIG. 6, so that the following can be seen: the binder is present in a large amount. Due to the presence of a large amount of binder, a dense metal member cannot be formed after the sintering process.
Comparative example 4
Comparative example 4 provides a method of additive manufacturing of hollowed-out metal components, differing from example 1 in that: in the binder removal step, the temperature was raised to 450 ℃ without heat preservation. The other steps are completely identical.
The hollow structural member of the comparative example, from which the binder was removed, had foaming and cracking defects, and after the sintering treatment, a defect-free thin-walled hollow metal member could not be formed.
In summary, the method for preparing the hollowed-out metal component for additive manufacturing provided by the embodiment of the invention is used for removing the adhesive without adopting a chemical reagent when preparing the hollowed-out metal component for additive manufacturing, and also ensuring the quality of the hollowed-out metal component.
The above description is only of the preferred embodiments of the present invention, and is not intended to limit the present invention in any way, but any simple modification, equivalent variation and modification made to the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.
Claims (10)
1. The preparation method of the hollowed-out metal component for additive manufacturing is characterized by comprising the following steps of:
and (3) printing: printing the raw materials into a printing piece with a hollow structure; wherein the components of the raw materials comprise metal particles and a thermoplastic polymer binder;
and (3) removing the binder: heating the hollowed-out structural printing piece to a set temperature in an environment with the oxygen content lower than 2ppm so as to remove the thermoplastic polymer binder in the hollowed-out structural piece and obtain the hollowed-out structural piece from which the binder is removed; the set temperature is determined by performing thermogravimetric analysis on the hollowed-out structure printing piece; the heating rate V for heating to the set temperature and the wall thickness t of the hollow-out structure printing piece are required to meet the following relation: v x t is less than or equal to 0.1mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.1mm and less than or equal to 1mm, and V is in a unit of ℃/min;
sintering treatment: and sintering the hollow structural member after the binder is removed to obtain the hollow metal member for additive manufacturing.
2. The method of manufacturing an additive manufacturing hollowed-out metal member according to claim 1, wherein in the printing step:
the thermoplastic polymer binder content in the raw materials is 8-14wt%, preferably 10-12wt%; the content of metal particles in the raw materials is 86-92wt%;
preferably, the raw materials also contain additives; further preferably, the content of the additive is 0 to 1.5wt%.
3. The method for producing a hollowed-out metal member for additive manufacturing according to claim 1 or 2, wherein the raw material is a wire; and/or
The metal particles are stainless steel particles, preferably 316L stainless steel particles; the thermoplastic polymer binder is polyoxymethylene POM.
4. A method of producing an additive manufacturing hollowed-out metal member according to any of claims 1 to 3, wherein in the printing step:
heating the raw materials, spraying the raw materials onto a printing platform through a nozzle, and printing to form a printing piece with a hollow structure;
preferably, the temperature of the nozzle is 1 to 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 ℃, preferably 100-120 ℃;
preferably, the printing speed is 5 to 30mm/s, more preferably 10 to 20mm/s.
5. The method of producing an additive manufacturing hollowed-out metal member according to any one of claims 1 to 4, wherein in the printing step:
the hollow-out structure printing piece is of a through hole structure, and all walls of the hollow-out structure printing piece are in contact with air.
6. The method of producing an additive manufacturing hollowed-out metal member according to any one of claims 1 to 5, wherein in the binder removal step:
the temperature rising rate V for heating to the set temperature and the wall thickness t of the hollow-out structure printing piece are required to meet the following relation: v x t is less than or equal to 0.3mm per minute and less than or equal to 0.4mm per minute; wherein t is more than or equal to 0.3mm and less than or equal to 0.6mm.
7. The method of producing an additive manufacturing hollowed-out metal member according to any one of claims 1 to 6, wherein in the binder removal step:
the environment with the oxygen content lower than 2ppm comprises a vacuum environment and an inert gas environment.
8. The method of producing an additive manufacturing hollowed-out metal member according to any one of claims 1 to 7, wherein in the binder removal step:
heating the hollow-out structure printing piece to a set temperature at a heating rate V, preserving heat for a set time, and cooling;
preferably, the set temperature is 380-420 ℃;
preferably, the setting time is 0 to 3 hours, preferably 0.5 to 3 hours, further preferably 1 to 2 hours;
preferably, the temperature rising rate V is 0.2-3 ℃/min, preferably 0.5-1 ℃/min.
9. The method of producing an additive manufacturing hollowed-out metal member according to any one of claims 1 to 8, wherein in the sintering treatment step:
heating the hollow structural member after removing the binder to a first sintering temperature at a first heating rate, preserving heat for a first time, then continuously heating to a second sintering temperature at a second heating rate, preserving heat for a second time, and cooling;
preferably, the first heating rate is 3-8 ℃/min, preferably 4-6 ℃/min; the second heating rate is 3-8 ℃/min, preferably 4-6 ℃/min;
preferably, the first sintering temperature is 500-700 ℃, preferably 600-700 ℃; the second sintering temperature is 1370-1380 ℃;
preferably, the first time is 0.5-2 hours, preferably 1-1.5 hours;
preferably, the second time is 2-3 hours.
10. An additive manufacturing hollowed-out metal component, characterized in that the additive manufacturing hollowed-out metal component is prepared by the preparation method of the additive manufacturing hollowed-out metal component according to any one of claims 1-9;
preferably, the hollow metal member for additive manufacturing is a stainless steel member; further preferably, the additive manufacturing hollowed-out metal component contains an austenite phase of twin crystals.
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