Manufacturing method of 3D printing molded body and control method of 3D printing molded body

Abstract

A method for manufacturing a 3D printed molded body is provided, comprising the steps of: mixing a metal powder and a polymer binder to produce a printing source; 3D printing the printing source using a 3D printer to produce a preform; and heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform.

Description

Technology Field

[0001] The present application relates to a method for manufacturing a 3D printed molded body and a method for controlling a 3D printed molded body, and more specifically, to a method for manufacturing a 3D printed molded body in which a polymer binder, which is heat-treated in a reduced pressure atmosphere to impart fluidity, fills a void and increases the density, and a method for controlling a 3D printed molded body. Background Technology

[0003] A 3D printed molded body can be manufactured by a method of stacking a printing source extruded through the nozzle of a 3D printer. For example, Korean Patent Publication No. 10-1644017 discloses a 3D printing method comprising a stacking step of forming a layer that forms a 3D printed structure by stacking a stacking material, a viscoelastic solution injection step in which a viscoelastic solution supply unit injects the viscoelastic solution to the same height as the layer, and a method of forming the 3D printed structure by alternately repeating the stacking step and the viscoelastic solution injection step.

[0004] Meanwhile, a 3D printed body manufactured using a 3D printer may contain voids between the stacked tracks. That is, although the 3D printed body may appear to be joined by contact between the stacked tracks, it may actually contain voids in non-contact areas between the tracks. The voids contained in the 3D printed body may be difficult to remove even at high temperatures of 1,000°C or higher. Rather, the voids contained in the 3D printed body may expand at high temperatures and form larger voids. Consequently, the 3D printed body manufactured by the 3D printer may have a low density and may exhibit mechanical anisotropy. As a result, the quality of the 3D printed body may deteriorate.

[0005] Accordingly, there is a need for a method to manufacture high-density 3D printed bodies. The problem to be solved

[0007] The technical problem that this application aims to solve is to provide a method for manufacturing a 3D printed molded body with high quality and increased density.

[0008] Another technical problem that the present application aims to solve is to provide a method for controlling a 3D printed molded body that controls the density of the molded body.

[0009] Another technical problem that this application aims to solve is to provide a method for controlling a 3D printed molded body that controls the porosity of the molded body.

[0010] The technical problems that this application aims to solve are not limited to those described above. means of solving the problem

[0012] To solve the above technical problem, the present application provides a method for manufacturing a three-dimensional printed molded body.

[0013] According to one embodiment, the method for manufacturing a three-dimensional printed body may include the steps of: mixing a metal powder and a polymer binder to produce a printing source; three-dimensionally printing the printing source using a three-dimensional printer to produce a preform; and heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform.

[0014] According to one embodiment, the method for manufacturing the three-dimensional printing molded body may include heat-treating the preform in a reduced pressure atmosphere to impart fluidity to the polymer binder of the preform, and the polymer binder imparting fluidity fills the voids of the preform to increase the density of the molded body.

[0015] According to one embodiment, the step of manufacturing the molded body is repeated at least once, and as the number of repetitions increases, the density of the molded body manufactured may increase.

[0016] According to one embodiment, the metal powder has a particle size of 1 μm or more to 10 μm or less, and in the reduced pressure atmosphere, the smaller the particle size of the metal powder, the higher the density of the molded body may be.

[0017] According to one embodiment, the heat treatment is performed at a temperature in which the polymer binder has viscosity, and by the heat treatment, the polymer binder may have a viscosity of 108 Pa·s or more to 1,020 Pa·s or less.

[0018] According to one embodiment, the heat treatment may be performed at 100°C or higher to 130°C or lower for 5 minutes or more to 20 minutes or less.

[0019] According to one embodiment, the reduced pressure atmosphere is 1 x 10 -2 It may include torr or higher to atmospheric pressure or lower.

[0020] According to one embodiment, the metal powder may be mixed in an amount of 50 vol% or more to less than 64 vol%.

[0021] According to one embodiment, the metal powder comprises iron, and the polymer binder may comprise at least one of paraffin wax, ethylvinyl alcohol, polyethylene, and stearic acid.

[0023] To solve the above technical problem, the present application provides a method for controlling a 3D printed molded body.

[0024] According to one embodiment, the method for controlling the three-dimensional printed body may include the step of preparing a preform by which a printing source comprising metal powder and a polymer binder is three-dimensionally printed using a three-dimensional printer, and the step of heat-treating the preform while controlling the pressure to control the density or porosity of the body produced from the preform.

[0025] According to one embodiment, the pressure is 1 x 10 -2 It may include adjusting the pressure to decrease or increase within a pressure range of torr or higher and below atmospheric pressure, wherein, when manufacturing the molded body with a higher density than the preformed body, the pressure may be adjusted to decrease within the pressure range or the particle size of the metal powder may be adjusted to decrease, and when manufacturing the molded body with a more porous structure than the preformed body, the pressure may be adjusted to increase within the pressure range or the particle size of the metal powder may be adjusted to decrease.

[0026] According to one embodiment, a method for controlling a 3D printed molded body may include repeating the heat treatment multiple times in a state where the pressure is lowered or the particle size of the metal powder is reduced when manufacturing the molded body with a higher density than the preformed body.

[0027] According to one embodiment, a method for controlling a 3D printed molded body may include, when the density of the molded body is precisely controlled to a second density lower than the first density defined as high density, a step of controlling the pressure to be lowered within the pressure range and a step of controlling the lowered pressure to atmospheric pressure are repeated multiple times as a unit process, and when the porosity of the molded body is precisely controlled to a second porosity lower than the first porosity defined as porosity of porosity, a step of controlling the pressure to be higher within the pressure range and a step of controlling the raised pressure to atmospheric pressure are repeated multiple times as a unit process. Effects of the invention

[0029] According to an embodiment of the present application, a method for manufacturing a 3D printed molded body may be provided, comprising the steps of: mixing a metal powder and a polymer binder to produce a printing source; 3D printing the printing source using a 3D printer to produce a preform; and heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform.

[0030] According to an embodiment of the present application, when the preform is heat-treated in a reduced pressure atmosphere, fluidity may be imparted to the polymer binder of the preform. Accordingly, the polymer binder imparted with fluidity may fill the voids of the preform, thereby increasing the density of the manufactured molded body. Accordingly, the quality of the molded body may be improved. Brief explanation of the drawing

[0032] FIG. 1 is a drawing for explaining a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application. FIG. 2 is a drawing for explaining the step of manufacturing a printing source in a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application. FIG. 3 is a drawing illustrating the step of manufacturing a preform in a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application. FIG. 4 is a drawing for explaining a cross-section of a preform according to an embodiment of the present application. FIG. 5 is a drawing for explaining the step of manufacturing a molded body in a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application. FIG. 6 is a drawing for explaining a cross-section of a molded body according to an embodiment of the present application. FIG. 7 is a drawing for explaining a method for controlling a three-dimensional printed molded body according to an embodiment of the present application. FIG. 8 is a drawing for explaining a three-dimensional printing molded body manufacturing apparatus according to an embodiment of the present application. FIG. 9 is a photograph illustrating a metal powder having an average particle size of 1 μm according to an experimental example of the present application. FIG. 10 is a graph of particle size analysis of metal powder according to an experimental example of the present application. FIG. 11 is a photograph illustrating a metal powder having an average particle size of 10 μm according to an experimental example of the present application. FIG. 12 is a graph illustrating the mixing amount of metal powder according to the experimental example of the present application. FIG. 13 is a drawing for explaining a printing source according to an experimental example of the present application. FIG. 14 is a drawing for explaining the three-dimensional modeling of a preform according to an experimental example of the present application. FIG. 15 is a drawing for explaining a 3D printer according to an experimental example of the present application. FIG. 16 is a drawing for illustrating a preform manufactured according to an experimental example of the present application. FIG. 17 is a differential scanning calorimeter (DSC) graph of a printing source according to an experimental example of the present application. FIG. 18 is a viscosity-pressure graph according to the temperature of a printing source according to an experimental example of the present application. FIG. 19 is a viscosity-shear rate graph according to the temperature of a printing source according to an experimental example of the present application. FIG. 20 is the result of micro-CT (micro-computed tomography) analysis of a preform and a molded body according to an experimental example of the present application. FIG. 21 is a graph showing the change in void length of a preform and a molded body according to an experimental example of the present application. FIG. 22 is the result of micro-CT analysis of the cross-section of a preform and a molded body according to the experimental example of the present application. FIG. 23 is an optical microscope image of a preform according to an experimental example of the present application. FIG. 24 is an optical microscope image of a molded body according to an experimental example of the present application. Specific details for implementing the invention

[0033] Hereinafter, preferred embodiments of the present application will be described in detail with reference to the attached drawings. However, the technical concept of the present application is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to ensure that the concept of the present application is sufficiently conveyed to those skilled in the art.

[0034] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of shapes and regions are exaggerated for the effective description of the technical content.

[0035] Additionally, although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. Accordingly, what is referred to as the first component in one embodiment may be referred to as the second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. Furthermore, in this specification, "and / or" is used to mean including at least one of the components listed before and after it.

[0036] In the specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, components, or combinations thereof described in the specification, and should not be understood as excluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. Additionally, in this specification, "connection" is used to include both indirectly connecting multiple components and directly connecting them.

[0037] Additionally, terms such as “…part,” “…unit,” and “module” described in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware, software, or a combination of hardware and software.

[0038] Furthermore, in describing the present application below, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the application, such detailed description will be omitted.

[0040] FIG. 1 is a drawing for explaining a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application, FIG. 2 is a drawing for explaining a step of manufacturing a printing source in a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application, FIG. 3 is a drawing for explaining a step of manufacturing a preform in a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application, FIG. 4 is a drawing for explaining a cross-section of a preform according to an embodiment of the present application, FIG. 5 is a drawing for explaining a step of manufacturing a molded body in a method for manufacturing a three-dimensional printed molded body according to an embodiment of the present application, and FIG. 6 is a drawing for explaining a cross-section of a molded body according to an embodiment of the present application.

[0041] Referring to FIGS. 1 and 2, a metal powder (1) and a polymer binder (3) are mixed to produce a printing source (5) (S110). At this time, the metal powder (1) may have a predetermined size, i.e., particle size. The metal powder (1) may have a particle size of, for example, 1 μm or more to 10 μm or less. However, it is not limited thereto.

[0042] According to one embodiment, in order to manufacture the printing source (5), the metal powder (1) may be mixed with the polymer binder (3) in a predetermined ratio. For example, the metal powder (1) may be mixed with the polymer binder (3) in an amount of 50 vol% or more and less than 64 vol% so that the total amount is 100 vol%. Accordingly, the viscosity of the printing source (5) manufactured including the metal powder (1) is increased, and the mixing for manufacturing the printing source (5) may be easy. More specifically, according to an embodiment of the present application, in the manufacture of the printing source (5), the metal powder (1) is mixed in the range described above, i.e., 50 vol% or more to less than 64 vol%, so that the printing source (5) may have a viscosity that is easy to extrude through a nozzle when 3D printed using a 3D printer (120, see FIG. 8) described later. That is, according to an embodiment of the present application, as the printing source (5) is manufactured by mixing the metal powder (1) in the range described above, i.e., 50 vol% or more to less than 64 vol%, the printing source (5) can be easily extruded through the 3D printer (120) and stably printed.

[0043] Meanwhile, unlike the embodiment of the present application, when the metal powder (1) is mixed at 64 vol% or more, the viscosity of the printing source being produced may be excessively high. As a result, a large amount of force, for example, rotational force (torque), may be required for mixing to produce the printing source, and thus mixing may be difficult. In addition, unlike the present application, if the viscosity of the printing source is excessively high, when the printing source is 3D printed using a 3D printer, the extrusion through the nozzle may not be smooth, and the printing may be unstable.

[0044] Alternatively, unlike the embodiments of the present application, if the metal powder (1) is mixed in an amount of less than 50 vol%, the viscosity of the printing source being produced may be excessively low. As a result, when the printing source is 3D printed using a 3D printer, it may be difficult to form the shape of the molded body being produced.

[0045] However, according to an embodiment of the present application, as described above, the metal powder (1) can be mixed with the polymer binder (3) in an amount of 50 vol% or more and less than 64 vol% so that the total amount is 100 vol%, thereby producing the printing source (5). Accordingly, the viscosity of the printing source (5) produced including the metal powder (1) is increased, and the mixing for producing the printing source (5) can be made easy. In addition, the printing source (5) can be easily extruded through the 3D printer (120) and printed stably.

[0046] According to one embodiment, the mixing of the metal powder (1) and the polymer binder (3) may be performed at a predetermined temperature. For example, the metal powder (1) and the polymer binder (3) may be mixed at 130°C or higher and 150°C or lower. More specifically, for example, the metal powder (1) and the polymer binder (3) may be mixed at 145°C. However, it is not limited thereto. The printing source (5) produced by mixing the metal powder (1) and the polymer binder (3) may be produced, for example, in the form of a feedstock. However, it is not limited thereto. The metal powder (1) may be, for example, iron powder, and more specifically, for example, the metal powder (1) may be a single-size pure iron powder. However, it is not limited thereto. The polymer binder (3) may include, for example, at least one of paraffin wax, ethylvinyl alcohol, polyethylene, and stearic acid. More specifically, for example, the polymer binder (3) may include 57 wt% paraffin wax, 20 wt% ethylvinyl alcohol, 20 wt% polyethylene, and 3 wt% stearic acid so that the total amount is 100 wt%. However, it is not limited thereto.

[0047] Referring further to FIGS. 1 and FIGS. 3, the printing source (5) can be 3D printed using a 3D printer (120, see FIG. 8) to manufacture a preform (10) (S120). More specifically, the printing source (5) provided to the 3D printer (120) can be extruded through a nozzle and deposited, thereby manufacturing the preform (10).

[0048] According to one embodiment, the extrusion of the printing source (5) using the 3D printer (120) can be performed at a predetermined temperature. For example, the printing source (5) can be extruded through the nozzle of the 3D printer (120) at a temperature of 140°C or higher and 160°C or lower. More specifically, for example, the printing source (5) can be extruded through the nozzle of the 3D printer (120) at 150°C. However, it is not limited thereto.

[0049] Meanwhile, the above-mentioned preform (10) may include voids (vd) as shown in FIG. 4. More specifically, the above-mentioned preform (10) may include voids (vd) between stacked tracks. As a result, the density of the above-mentioned preform (10) may be low.

[0050] Referring further to FIGS. 1 and FIG. 5, the preform (10) may be heat-treated in a reduced pressure atmosphere to produce a molded body (20) with a higher density than the preform (10) (S130). More specifically, the heat treatment may be performed at a temperature in which the polymer binder (3) has viscosity. In other words, the heat treatment may be performed at a temperature in which the polymer binder (3) melts. As a result, the polymer binder (3) may have viscosity. For example, the polymer binder (3) may have a viscosity of 108 Pa·s or more to 1,020 Pa·s or less by the heat treatment. However, it is not limited thereto. The heat treatment may be performed, for example, at 100°C or more to 130°C or less for 5 minutes or more to 20 minutes or less. More specifically, for example, the heat treatment may be performed at 110°C for 15 minutes. However, it is not limited to this.

[0051] According to an embodiment of the present application, the preform (10) may be heat-treated in a reduced pressure atmosphere to impart fluidity to the polymer binder (3) of the preform (10). This may be because, as previously described, the heat treatment is performed at a temperature in which the polymer binder (3) has viscosity. The polymer binder (3) imparted fluidity can fill the voids (vd) of the preform (10), as illustrated in FIG. 6. As a result, the density of the molded body (20) may be increased. Furthermore, the molded body (20) manufactured by heat-treating the preform (10) in a reduced pressure atmosphere may maximize bonding between stacked tracks. The reduced pressure atmosphere is, for example, 1 X 10 -2 It may include torr or higher and atmospheric pressure or lower. However, it is not limited thereto.

[0052] According to one embodiment, in the reduced pressure atmosphere, the density of the molded body (20) produced may be higher as the particle size of the metal powder (1) becomes smaller. As described above, the metal powder (1) may have a particle size of 1 μm or more to 10 μm or less, but is not limited thereto.

[0053] According to an embodiment of the present application, the step of manufacturing the molded body (20) can be repeated at least once, and as the number of repetitions increases, the density of the molded body (20) being manufactured can be increased. Accordingly, the quality of the molded body (20) can be improved.

[0055] FIG. 7 is a drawing for explaining a method for controlling a three-dimensional printed molded body according to an embodiment of the present application.

[0056] Referring to FIG. 7, the preform (10, FIG. 3) can be prepared by 3D printing the printing source (5, FIG. 2) containing the metal powder (1, FIG. 2) and the polymer binder (3, FIG. 2) using a 3D printer (120, FIG. 8) (S210). Alternatively, the preform (10) may be a preform manufactured using a conventional 3D printer. In other words, the preform (10) may be prepared by the manufacturing method described above with reference to FIG. 1 to 3, or a preform formed in the past may be prepared.

[0057] When the above preform (10) is prepared, the preform (10) is heat-treated while the pressure is controlled so that the density or porosity of the molded body (20) manufactured from the preform (10) can be controlled (S220). At this time, the heat treatment can be performed, for example, at 110°C for 15 minutes, and the pressure is 1 x 10 -2 It can be adjusted to decrease or increase within a pressure range of torr or higher and below atmospheric pressure. However, it is not limited thereto. Additionally, the particle size of the metal powder (1) can be adjusted to decrease or increase within, for example, 1 μm or more and 10 μm or less. However, it is not limited thereto.

[0058] According to one embodiment, when the molded body (20) is manufactured with a higher density than the preformed body (10), the pressure may be adjusted to be lower within the pressure range. Alternatively, when the molded body (20) is manufactured with a higher density than the preformed body (10), the particle size of the metal powder (1) may be adjusted to be smaller. For example, when the molded body (20) is manufactured with a higher density than the preformed body (10), the pressure is 2 x 10 -2 It can be controlled to torr, or, the metal powder (1) can have a particle size of 1 μm.

[0059] Meanwhile, when the molded body (20) with a higher density than the preformed body (10) is manufactured, the heat treatment may be repeated multiple times while the pressure is controlled to be lowered or the particle size of the metal powder (1) is controlled to be smaller. For example, when the molded body (20) with a higher density than the preformed body (10) is manufactured, the preformed body (10) manufactured including the metal powder (1) having a particle size of 1 μm, the pressure 2 X 10 -2 At torr, it can be heat-treated at 110°C for 15 minutes, and the heat treatment can be repeated two or more times.

[0060] On the other hand, if the molded body (20) is manufactured to be more porous than the preformed body (10), the pressure may be controlled to be higher within the pressure range. Alternatively, if the molded body (20) is manufactured to be more porous than the preformed body (10), the particle size of the metal powder (1) may be controlled to be smaller. For example, if the molded body (20) is manufactured to be more porous than the preformed body (10), the pressure may be controlled to 2 torr, or the metal powder (1) may have a particle size of 1 μm.

[0061] Meanwhile, according to an embodiment of the present application, the density and porosity of the molded body (20) can be precisely controlled. More specifically, when the density of the molded body (20) is precisely controlled to a second density lower than the first density defined as high density, the step of adjusting the pressure to be lowered within the pressure range and the step of adjusting the lowered pressure to atmospheric pressure can be repeated multiple times as a unit process. For example, the unit process can be repeated three times.

[0062] On the other hand, when the porosity of the molded body (20) is precisely controlled to a second porosity lower than the first porosity defined by the porosity of the above porosity, the step of adjusting the pressure to increase within the pressure range and the step of adjusting the increased pressure to atmospheric pressure may be repeated multiple times as a unit process. For example, the unit process may be repeated three times.

[0064] FIG. 8 is a drawing for explaining a three-dimensional printing molded body manufacturing apparatus according to an embodiment of the present application.

[0065] Referring to FIG. 8, the 3D printing molded body manufacturing device (100) may include a mixing unit (110) that mixes the metal powder (1) and the polymer binder (3) to produce the printing source (5), a 3D printer (120) that 3D prints the printing source (5) to produce the preform (10), and a density control unit (130) that heat-treats the preform (10) in a reduced pressure atmosphere to produce the molded body (20) which has a higher density than the preform (10).

[0066] More specifically, the mixing unit (110) may include at least one of a tank into which the metal powder (1) and the polymer binder (3) are introduced, a heater provided on one side of the tank to heat the tank, and a screw provided with a rotating blade for mixing the metal powder (1) and the polymer binder (3) introduced into the tank. Accordingly, the metal powder (1) and the polymer binder (3) are mixed through the mixing unit (110), and the printing source (5) can be manufactured.

[0067] The above 3D printer (120) may include at least one of a hopper into which the printing source (5) is fed, a motor that pushes the printing source (5) of the hopper through a barrel to a nozzle, a heating unit provided adjacent to the nozzle to apply heat to the printing source (5) provided by the motor, a printing bed on which the preform (10) manufactured by extruding the heated printing source (5) through the nozzle is placed, and a cooling fan that cools the preform (10) placed on the printing bed. Accordingly, the printing source (5) can be 3D printed through the 3D printer (120) to manufacture the preform (10).

[0068] The density control unit (130) may include at least one of a chamber into which the preform (10) is introduced, a heater provided on one side of the chamber to heat the preform (10) introduced into the chamber, a pump for controlling the pressure inside the chamber, and a pipe connecting the chamber and the pump. Accordingly, through the density control unit (130), the preform (10) is heat-treated in a reduced pressure atmosphere, thereby producing a molded body (20) with a higher density than the preform (10). The molded body (20) may have a higher density than the preform (10) by controlling the pressure inside the chamber to be lowered or by controlling the particle size of the metal powder (1) to be smaller. As this overlaps with the previously described embodiment, it is recommended to refer to the previously described embodiment.

[0069] Alternatively, the porous molded body (20) may be manufactured by controlling the pressure inside the chamber to increase or controlling the particle size of the metal powder (1) to increase through the density control unit (130). Since this overlaps with the previously described embodiment, we will refer to the previously described embodiment.

[0071] Hereinafter, experimental examples of the present application are described.

[0073] FIG. 9 is a photograph illustrating a metal powder having an average particle size of 1 μm according to an experimental example of the present application, FIG. 10 is a graph of the particle size analysis of the metal powder according to an experimental example of the present application, and FIG. 11 is a photograph illustrating a metal powder having an average particle size of 10 μm according to an experimental example of the present application.

[0074] Referring to FIG. 9, the metal powder (1) having an average particle size of 1 μm prepared according to the experimental example of the present application can be observed. Referring to FIG. 10, it can be demonstrated that the metal powder (1) has an average particle size of 1 μm. Additionally, referring to FIG. 11, the metal powder (1) having an average particle size of 10 μm prepared according to the experimental example of the present application can be observed.

[0076] FIG. 12 is a graph for explaining the mixing amount of metal powder according to an experimental example of the present application, and FIG. 13 is a drawing for explaining a printing source according to an experimental example of the present application.

[0077] Referring to FIG. 12, the optimal mixing amount of the metal powder (1) for manufacturing the printing source (5) can be derived according to the experimental example of the present application. To derive the optimal mixing amount of the metal powder (1), the amount of the metal powder (1) was increased by 2 vol% and mixed with the polymer binder (3). When the amount of the metal powder (1) being mixed was 64 vol%, the mixing torque for mixing the metal powder (1) and the polymer binder (3) increased rapidly, as shown in FIG. 12.

[0078] Accordingly, according to the experimental example of the present application, the metal powder (1) can be mixed in an amount of less than 64 vol% to manufacture the printing source (5).

[0079] Referring to FIG. 13, the printing source (5) prepared according to the mixture amount derived in the experimental example of the present application can be observed.

[0081] FIG. 14 is a drawing for explaining the three-dimensional modeling of a preform according to an experimental example of the present application, FIG. 15 is a drawing for explaining a three-dimensional printer according to an experimental example of the present application, and FIG. 16 is a drawing for explaining a preform manufactured according to an experimental example of the present application.

[0082] Referring to FIG. 14(a) and FIG. 14(b), the results of three-dimensional modeling to manufacture the preform (10) according to the experimental example of the present application can be observed. In the experimental example of the present application, the preform (10) is manufactured in a cylindrical shape including a hollow, and a track may be formed by stacking tracks from the lower side to the upper side.

[0083] Referring to FIG. 15, the 3D printer (120) for manufacturing the preform (10) can be observed. As previously described, the 3D printer (120) may include at least one of a hopper (hp) into which the printing source (5) is introduced, a motor (mt) that pushes the printing source (5) from the hopper (hp) through a barrel (br) to a nozzle, a heating unit (not shown) provided adjacent to the nozzle (nz) to apply heat to the printing source (5) provided by the motor (mt), a printing bed (pb) on which the preform (10) manufactured by extruding the heated printing source (5) through the nozzle (nz) is placed, and a cooling fan (cp) that cools the preform (10) placed on the printing bed (pb).

[0084] Referring to FIG. 16, the preform (10) manufactured according to the experimental example of the present application can be observed. It can be seen that the preform (10) is manufactured in a cylindrical shape according to the result of the three-dimensional modeling (see FIG. 14).

[0086] FIG. 17 is a differential scanning calorimeter (DSC) graph of a printing source according to an experimental example of the present application, FIG. 18 is a viscosity-pressure graph according to temperature of a printing source according to an experimental example of the present application, and FIG. 19 is a viscosity-shear rate graph according to temperature of a printing source according to an experimental example of the present application.

[0087] Referring to FIG. 17, it can be seen that the printing source (5) according to the experimental example of the present application melts at a temperature of 105°C or higher. This means that the polymer binder (3) contained in the printing source (5) melts at a temperature of 105°C or higher. Accordingly, according to the experimental example of the present application, the heat treatment of the preform (10) for manufacturing the molded body (20) can be performed at 105°C or higher.

[0088] Referring to FIG. 18, the viscosity-pressure relationship according to the temperature of the printing source (5) can be examined. Through the graph shown in FIG. 18, the slope value at each temperature can be derived using Equation 1 below.

[0089] <Equation 1>

[0090] lnη = β·p + c

[0091] Here, lnη is viscosity, β is slope, p is pressure, and c is a constant, that is, the natural logarithm of viscosity (lnη) at low pressure (p).

[0093] The slope value according to the temperature of the printing source (5) derived through the above Equation 1 can be summarized as shown in Table 1 below.

[0094] Temperature (°C) Slope (β) 110 -0.1154 115 -0.1149 120 -0.1167 125 -0.1039 130 -0.093

[0096] Referring to FIG. 19, the viscosity-shear rate relationship according to the temperature of the printing source (5) can be examined.

[0097] As can be seen from FIG. 19, the printing source (5) has a viscosity of 108 Pa·s or more and 1,020 Pa·s or less depending on the temperature.

[0099] Preparation of a molded body (ex1-1) according to Experimental Example 1-1

[0100] 60 vol% of iron powder having an average particle size of 1 μm as the metal powder (1), and 40 vol% of the polymer binder (3) containing 57 wt% paraffin wax, 20 wt% ethyl vinyl alcohol, 20 wt% polyethylene, and 3 wt% stearic acid were introduced into a tank, and the printing source (5) was prepared in the form of a feedstock by mixing at a rotational speed of 60 rpm while maintaining the internal temperature of the tank at 145 ℃.

[0101] The above printing source (5) was fed into the hopper of a 3D printer and extruded at a speed of 17.5 mm / s through a nozzle of 150°C having a diameter of 0.8 mm and a layer thickness of 0.2 mm to produce the above preform (10).

[0102] 2 X 10 -2 The above preform (10) was heat-treated at 110°C for 5 minutes in a torr to produce a molded body (ex1-1) according to Experimental Example 1-1.

[0104] Preparation of a molded body (ex1-2) according to Experimental Example 1-2

[0105] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 110°C for 8 minutes to produce a molded body (ex1-2) according to Experimental Example 1-2.

[0107] Preparation of a molded body (ex1-3) according to Experimental Example 1-3

[0108] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 110°C for 10 minutes to produce a molded body (ex1-3) according to Experimental Example 1-3.

[0110] Preparation of a molded body (ex1-4) according to Experimental Example 1-4

[0111] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 110°C for 15 minutes to produce a molded body (ex1-4) according to Experimental Example 1-4.

[0113] Preparation of a molded body (ex1-5) according to Experimental Example 1-5

[0114] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 110°C for 18 minutes to produce a molded body (ex1-5) according to Experimental Example 1-5.

[0116] Preparation of a molded body (ex1-6) according to Experimental Example 1-6

[0117] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 115°C for 5 minutes to produce a molded body (ex1-6) according to Experimental Example 1-6.

[0119] Preparation of a molded body (ex1-7) according to Experimental Example 1-7

[0120] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 115°C for 8 minutes to produce a molded body (ex1-7) according to Experimental Example 1-7.

[0122] Preparation of a molded body (ex1-8) according to Experimental Example 1-8

[0123] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 115°C for 10 minutes to produce a molded body (ex1-8) according to Experimental Example 1-8.

[0125] Preparation of a molded body (ex1-9) according to Experimental Example 1-9

[0126] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 120°C for 5 minutes to produce a molded body (ex1-9) according to Experimental Example 1-9.

[0128] Preparation of a molded body (ex1-10) according to Experimental Example 1-10

[0129] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 120°C for 8 minutes to produce a molded body (ex1-10) according to Experimental Example 1-10.

[0131] Preparation of a molded body (ex1-11) according to Experimental Example 1-11

[0132] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 120°C for 10 minutes to produce a molded body (ex1-11) according to Experimental Example 1-11.

[0134] Preparation of a molded body (ex1-12) according to Experimental Example 1-12

[0135] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 125°C for 5 minutes to produce a molded body (ex1-12) according to Experimental Example 1-12.

[0137] The above-described experimental examples 1-1 to 1-12 (ex1-1 to ex1-12) can be summarized as shown in Table 2 below. Table 2 below summarizes the thickness and density of the above-described preform (10) and the above-described molded body (20) in experimental examples 1-1 to 1-12 (ex1-1 to ex1-12).

[0138] division Pressure (torr) Temperature (°C) Time (minutes) Thickness (outer diameter - inner diameter) density Preform (mm) Molded body (mm) Preformed body (%) Molded body (%) ex1-1 2 X 10 -2 110 5 2.54 2.50 97.4 97.1 ex1-2 2 X 10 -2 110 8 2.59 2.58 98.1 98.5 ex1-3 2 X 10 -2 110 10 2.60 2.61 97.8 98.4 ex1-4 2 X 10 -2 110 15 2.55 2.54 97.2 99.4 ex1-5 2 X 10 -2 110 18 2.58 2.94 melting ex1-6 2 X 10 -2 115 5 2.62 2.58 97.4 97.9 ex1-7 2 X 10 -2 115 8 2.57 2.55 97.9 98.1 ex1-8 2 X 10 -2 115 10 2.58 2.56 96.6 97.8 ex1-9 2 X 10 -2 120 5 2.58 2.58 96.3 97.0 ex1-10 2 X 10 -2 120 8 2.56 2.55 97.0 97.6 ex1-11 2 X 10 -2 120 10 2.55 3.25 melting ex1-12 2 X 10 -2 125 5 2.58 2.59 97.6 98.3

[0140] Referring to Table 2 above, it can be seen that the density characteristics of the molded body (ex1-4) according to Experimental Example 1-4 are the best. More specifically, according to Experimental Example 1-4 (ex1-4), 2 X 10 -2 It can be seen that the density of the manufactured molded body (10) is highest when heat-treated at 110°C for 15 minutes at torr. In addition, according to Experimental Example 1-4 (ex1-4), the above preformed body (10) is 2 x 10 -2When heat-treated at 110°C for 15 minutes in torr, the density of the molded body (20) increases by 2.2% compared to the pre-molded body (10), which is a much greater increase than in other experimental examples. In particular, when comparing experimental examples 1-2 to 1-5, it can be seen that the density of the molded body (20) gradually increased by 0.4% in experimental example 1-2, 0.6% in experimental example 1-3, and 2.2% in experimental example 1-4, until the molded body (20) melted in experimental example 1-5. Thus, 2 X 10 -2 The critical significance of the molded body (ex1-4) according to Experimental Example 1-4, which is manufactured when heat-treated at 110 ℃ for 15 minutes at torr, can be understood.

[0141] Accordingly, the heat treatment temperature and time were fixed according to Experimental Example 1-4 (ex1-4), and the pressure was set to high vacuum (2 x 10 -2 Experimental Examples 2-1 to 2-6 (ex2-1 to ex2-6) were conducted by adjusting the pressure to various levels, such as torr), medium vacuum (2 torr), and / or atmospheric pressure (760 torr).

[0143] Preparation of a molded body (ex2-1) according to Experimental Example 2-1

[0144] A molded body (ex2-1) according to Experimental Example 2-1 was prepared using the same method as Experimental Example 1-4 described above.

[0146] Preparation of a molded body (ex2-2) according to Experimental Example 2-2

[0147] In the above-described Experimental Example 1-1, the above-described preform (10) was heat-treated at 110°C for 15 minutes in a medium vacuum (2 torr) to produce a molded body (ex2-2) according to Experimental Example 2-2.

[0149] Preparation of a molded body (ex2-3) according to Experimental Example 2-3

[0150] In the above-described Experimental Example 1-1, the preform (10) is placed in a high vacuum (2 x 10 -2A molded body (ex2-3) according to Experimental Example 2-3 was prepared by heat treating at 110°C for 15 minutes in torr, at 110°C for 15 minutes at atmospheric pressure, at 110°C for 15 minutes in high vacuum, at 110°C for 15 minutes at atmospheric pressure, and at 110°C for 15 minutes in high vacuum.

[0152] Preparation of a molded body (ex2-4) according to Experimental Example 2-4

[0153] In the above-described Experimental Example 1-1, the preform (10) was heat-treated at 110°C for 15 minutes in a medium vacuum, at 110°C for 15 minutes at atmospheric pressure, at 110°C for 15 minutes in a medium vacuum, at 110°C for 15 minutes at atmospheric pressure, and at 110°C for 15 minutes in a medium vacuum to produce a molded body (ex2-4) according to Experimental Example 2-4.

[0155] Preparation of a molded body (ex2-5) according to Experimental Example 2-5

[0156] In the above-described Experimental Example 2-1, iron powder having an average particle size of 10 μm was prepared using the metal powder (1), and a molded body (ex2-5) according to Experimental Example 2-5 was manufactured.

[0158] Preparation of a molded body (ex2-6) according to Experimental Example 2-6

[0159] In the above-described Experimental Example 2-2, iron powder having an average particle size of 10 μm was prepared using the metal powder (1), and a molded body (ex2-6) according to Experimental Example 2-6 was manufactured.

[0161] Experimental Examples 2-1 to 2-6 described above can be summarized as shown in Table 3 below. Table 3 below summarizes the thickness and density of the preform (10) and the molded body (20) in Experimental Examples 2-1 to 2-6 described above.

[0162] division Average particle size of metal powder (μm) Pressure (temperature (110℃) and time (15 min) are fixed) Thickness (outer diameter - inner diameter) density Preform (mm) Molded body (mm) Preformed body (%) Molded body (%) ex2-1 1 High vacuum (2 x 10 -2 torr) 2.55 2.54 97.2 99.4 ex2-2 1 SME Corporation (2 torr) 2.72 2.83 94.5 92.8 ex2-3 1 High vacuum, atmospheric pressure, high vacuum, atmospheric pressure, high vacuum 2.60 2.62 93.4 94.5 ex2-4 1 Medium vacuum, atmospheric pressure, medium vacuum, atmospheric pressure, medium vacuum 2.60 2.83 93.9 93.1 ex2-5 10 High vacuum 2.41 2.44 98.1 99.2 ex2-6 10 Korea Small Business Corporation 2.43 2.88 97.7 97.1

[0164] Referring to Table 3 above, the same high vacuum pressure (2 x 10 -2In torr), it can be seen that the density of the molded body (ex2-1) according to Experimental Example 2-1 increased by 2.2%, while the density of the molded body (ex2-5) according to Experimental Example 2-5 increased by 1.1%. Accordingly, it can be seen that in order to increase the density of the molded body (20), a lower reduced pressure atmosphere is required when the particle size of the metal powder (1) is larger than when it is smaller. In other words, when controlling to increase the density of the molded body (20), the particle size of the metal powder (1) can be controlled to become smaller at the same high vacuum pressure. Also, from another perspective, when controlling to increase the density of the molded body (20), the pressure can be controlled to become lower as the particle size of the metal powder (1) of the pre-molded body (10) increases.

[0165] In addition, referring to Table 3 above, it can be seen that at the same medium vacuum pressure (2 torr), the density of the molded body (ex2-2) according to Experimental Example 2-2 decreased by 1.7%, while the density of the molded body (ex2-6) according to Experimental Example 2-6 decreased by 0.6%. From another perspective, this may mean that at the medium vacuum pressure, the porosity of the molded body (ex2-2) according to Experimental Example 2-2 is higher than the porosity of the molded body (ex2-6) according to Experimental Example 2-6. In other words, if the porosity of the molded body (20) is controlled to increase, the particle size of the metal powder (1) can be controlled to decrease at the same medium vacuum pressure.

[0166] In addition, by referring to Table 3 above and comparing Experimental Example 2-1 (ex2-1) and Experimental Example 2-3 (ex2-3), it can be seen that the density of the molded body (ex2-1) according to Experimental Example 2-1 increased by 2.2%, while the density of the molded body (ex2-3) according to Experimental Example 2-3 increased by 1.1%. If the density of the molded body (ex2-1) according to Experimental Example 2-1, which increased more, is defined as the first density, and the density of the molded body (ex2-3) according to Experimental Example 2-3, which is lower than the first density, is defined as the second density, then when the density of the molded body (20) is precisely controlled to the second density, which is lower than the first density, the step of controlling to the high vacuum and the step of controlling to the atmospheric pressure can be repeated multiple times as a unit process at the same particle size of the metal powder (1) of 1 μm.

[0167] In addition, by referring to Table 3 above and comparing Experimental Example 2-2 (ex2-2) and Experimental Example 2-4 (ex2-4), it can be seen that the density of the molded body according to Experimental Example 2-2 (ex2-2) decreased by 1.7%, while the density of the molded body according to Experimental Example 2-4 (ex2-4) decreased by 0.8%. From another perspective, this may mean that the porosity of the molded body according to Experimental Example 2-4 (ex2-4) is lower than that of the molded body according to Experimental Example 2-2 (ex2-2). If the porosity of a molded body (ex2-2) according to experiment example 2-2, which has a high porosity, is defined as the first porosity, and the porosity of a molded body (ex2-4) according to experiment example 2-4, which has a lower porosity than the first porosity, is defined as the second porosity, then when the porosity of the molded body (20) is precisely controlled to a second porosity lower than the first porosity, the step of controlling to a medium vacuum and the step of controlling to atmospheric pressure can be repeated multiple times as a unit process at the same particle size of 1 μm of the metal powder (1).

[0169] FIG. 20 is a micro-CT (micro-computed tomography) analysis result of a preform and a molded body according to an experimental example of the present application, FIG. 21 is a graph of the change in pore length of a preform and a molded body according to an experimental example of the present application, FIG. 22 is a cross-sectional micro-CT analysis result of a preform and a molded body according to an experimental example of the present application, FIG. 23 is an optical microscope image of a preform according to an experimental example of the present application, and FIG. 24 is an optical microscope image of a molded body according to an experimental example of the present application.

[0170] Referring to FIG. 20, a preform (10) according to an experimental example of the present application can be observed through FIG. 20(a) and a molded body (20) according to an experimental example of the present application can be observed through FIG. 20(b). The preform (10) and the molded body (20) illustrated in FIG. 20(a) and FIG. 20(b), respectively, were manufactured through the manufacturing method according to Experimental Example 1-4 or Experimental Example 2-1 described above. Referring to FIG. 20(a) and FIG. 20(b), many voids (pr) exist in the preform (10) before heat treatment, whereas most of the voids (pr) are not observed in the molded body (20) after heat treatment. Thus, through the heat treatment, the polymer binder (3) can fill the voids (pr) of the preform (10), and it can be proven that the density of the molded body (20) produced is maximized.

[0171] Referring to FIG. 21, changes in the length of the pores (pr) of the preform (10) and the molded body (20) according to Experimental Example 1-4 or Experimental Example 2-1 of the present application can be observed. Referring to FIG. 21, it can be seen that the preform (10) before the heat treatment has many pores (pr) and the length of the pores (pr) is relatively long, whereas the molded body (20) after the heat treatment has most of the pores (pr) not observed and the length of the pores (pr) is short. Thus, it can be proven that through the heat treatment, the polymer binder (3) can fill the pores (pr) of the preform (10), and thereby the density of the molded body (20) manufactured is maximized.

[0172] Referring to FIG. 22, as illustrated in FIG. 22(a), a preform (10) and a molded body (20) according to Experimental Example 1-4 or Experimental Example 2-1 of the present application were cut, and the cross-section of the preform (10) can be observed through FIG. 22(b) and the cross-section of the molded body (20) through FIG. 22(c). Referring to FIG. 22(b), many voids (pr) are observed in the preform (10) before heat treatment, whereas referring to FIG. 22(c), voids (pr) are substantially not observed in the molded body (20) after heat treatment. Thus, it can be demonstrated that through the heat treatment, the polymer binder (3) can fill the voids (pr) of the preform (10), thereby maximizing the density of the molded body (20) produced.

[0173] Referring to FIG. 23, the cross-section and longitudinal section of a preform (10) according to Experimental Example 1-4 or Experimental Example 2-1 of the present application can be observed, and referring to FIG. 24, the cross-section and longitudinal section of a molded body (20) according to Experimental Example 1-4 or Experimental Example 2-1 of the present application can be observed. Referring to FIG. 23, many long voids (pr) are observed in the preform (10) before the heat treatment, whereas referring to FIG. 24, voids (pr) are substantially not observed in the molded body (20) after the heat treatment. Thus, it can be demonstrated that through the heat treatment, the polymer binder (3) can fill the voids (pr) of the preform (10), thereby maximizing the density of the molded body (20) produced.

[0175] Preparation of a molded body (ex3-1) according to Experimental Example 3-1

[0176] 60 vol% of iron powder having an average particle size of 1 μm as the metal powder (1), and 40 vol% of the polymer binder (3) containing 57 wt% paraffin wax, 20 wt% ethyl vinyl alcohol, 20 wt% polyethylene, and 3 wt% stearic acid were introduced into a tank, and the printing source (5) was prepared in the form of a feedstock by mixing at a rotational speed of 60 rpm while maintaining the internal temperature of the tank at 145 ℃.

[0177] The above printing source (5) was fed into the hopper of a 3D printer and extruded at a speed of 17.5 mm / s through a nozzle of 150°C having a diameter of 0.8 mm and a layer thickness of 0.2 mm to produce the above preform (10).

[0178] 2 X 10 -2 The above preform (10) was heat-treated at 110°C for 15 minutes in a torr to produce a molded body (ex1-1) according to Experimental Example 1-1.

[0180] Preparation of a molded body (ex3-2) according to Experimental Example 3-2

[0181] Experimental Example 3-1 described above was repeated twice to produce a molded body (ex3-2) according to Experimental Example 3-2.

[0183] Experimental Example 3-1 and Experimental Example 3-2 (ex3-1, ex3-2) described above can be summarized as shown in Table 4 below. Table 4 below summarizes the thickness and density of the preform (10) and the molded body (20) in Experimental Example 3-1 and Experimental Example 3-2 (ex3-1, ex3-2) described above.

[0184] division Average particle size of metal powder (μm) Temperature, time, pressure Thickness (outer diameter - inner diameter) density Preform (mm) Molded body (mm) Preformed body (%) Molded body (%) ex3-1 1 110℃, 15 min, 2 x 10 -2 torr 2.61 2.64 96.4 97.1 ex3-2 1 110℃, 15 min, 2 x 10 -2 torr 2.64 2.63 97.1 97.5

[0186] Referring to Table 4 above, it can be seen that the density of the molded body according to Experimental Example 3-2 (ex3-2) increased by 0.4% compared to the molded body according to Experimental Example 3-1 (ex3-1). Accordingly, the preformed body (10) containing the metal powder (1) having a particle size of 1 μm is 2 x 10 -2 It can be seen that when the process of heat treatment at 110°C for 15 minutes in torr is repeated multiple times, the density of the molded body (20) being manufactured increases. That is, from another perspective, when the density of the molded body (20) is controlled to increase, the pre-molded body (10) containing the metal powder (1) having a particle size of 1 μm is 2 x 10 -2 The process of heat treating at 110°C for 15 minutes at torr can be repeated multiple times.

[0188] Although the present application has been described in detail using preferred embodiments, the scope of the present application is not limited to specific embodiments and should be interpreted by the appended claims. Furthermore, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the present application. Explanation of the symbols

[0190] 1: Metal powder 3: Polymer binder 5: Print source 10: Preform 20: Molded body

Claims

Claim 1 A method for manufacturing a 3D printed molded body, comprising: a step of mixing a metal powder and a polymer binder to produce a printing source; a step of 3D printing the printing source using a 3D printer to produce a preform; and a step of heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform, wherein heat-treating the preform in the reduced pressure atmosphere imparts fluidity to the polymer binder of the preform, and the polymer binder imparting fluidity fills the voids of the preform, thereby increasing the density of the molded body. Claim 2 delete Claim 3 A method for manufacturing a 3D printed molded body according to claim 1, wherein the step of manufacturing the molded body is repeated at least once, and the density of the molded body manufactured increases as the number of repetitions increases. Claim 4 A method for manufacturing a 3D printed molded body according to claim 1, wherein the metal powder has a particle size of 1 μm or more to 10 μm or less, and wherein, in the reduced pressure atmosphere, the density of the molded body increases as the particle size of the metal powder decreases or the vacuum degree increases. Claim 5 A method for manufacturing a 3D printed molded body, comprising: a step of mixing a metal powder and a polymer binder to produce a printing source; a step of 3D printing the printing source using a 3D printer to produce a preform; and a step of heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform, wherein the heat treatment is performed at a temperature in which the polymer binder has viscosity, and wherein the polymer binder has a viscosity of 108 Pa·s or more to 1,020 Pa·s or less as a result of the heat treatment. Claim 6 A method for manufacturing a 3D printed molded body, comprising: a step of mixing a metal powder and a polymer binder to produce a printing source; a step of 3D printing the printing source using a 3D printer to produce a preform; and a step of heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform, wherein the heat treatment is performed at 100°C or higher to 130°C or lower for 5 minutes or more to 20 minutes or less. Claim 7 In claim 1, the reduced pressure atmosphere is 1 x 10 -2 A method for manufacturing a three-dimensional printed molded body comprising torr or higher and atmospheric pressure or lower. Claim 8 A method for manufacturing a 3D printed molded body, comprising: a step of mixing a metal powder and a polymer binder to produce a printing source; a step of 3D printing the printing source using a 3D printer to produce a preform; and a step of heat-treating the preform in a reduced pressure atmosphere to produce a molded body having a higher density than the preform, wherein the metal powder is mixed in an amount of 50 vol% or more and less than 64 vol%. Claim 9 A method for manufacturing a three-dimensional printed molded body according to claim 1, wherein the metal powder comprises iron, and the polymer binder comprises at least one of paraffin wax, ethylvinyl alcohol, polyethylene, and stearic acid. Claim 10 delete Claim 11 The method comprises the steps of: preparing a preform by 3D printing a printing source comprising metal powder and a polymer binder using a 3D printer; and heat-treating the preform while controlling the pressure to control the density or porosity of a molded body produced from the preform, wherein the pressure is 1 X 10 -2 It includes being adjusted to decrease or increase within a pressure range of torr or higher to less than atmospheric pressure, wherein the pressure range is 2 x 10 -2 A method for controlling a 3D printed molded body, comprising a high vacuum pressure of torr and a medium vacuum pressure of 2 torr, wherein when manufacturing the molded body which is more dense than the preformed body, the pressure is lowered within the pressure range or the particle size of the metal powder is reduced at the high vacuum pressure, and when manufacturing the molded body which is more porous than the preformed body, the pressure is raised within the pressure range or the particle size of the metal powder is reduced at the medium vacuum pressure. Claim 12 A method for controlling a 3D printed molded body according to claim 11, comprising repeating the heat treatment multiple times in a state in which the pressure is lowered or the particle size of the metal powder is reduced at the high vacuum pressure when manufacturing the molded body having a higher density than the preformed body. Claim 13 A method for controlling a 3D printed molded body according to claim 11, comprising: a step of controlling to a high vacuum pressure within a pressure range when precisely controlling the density of the molded body to a second density lower than the first density defined as the high density; and repeating the step of controlling the high vacuum pressure to atmospheric pressure multiple times as a unit process, and a step of controlling to a medium vacuum pressure within a pressure range when precisely controlling the porosity of the molded body to a second porosity lower than the first porosity defined as the porosity of the porous body; and repeating the step of controlling the medium vacuum pressure to atmospheric pressure multiple times as a unit process.

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