Manufacturing methods of shapes

Abstract

To provide a method for manufacturing molded objects that can improve the adhesive strength at the interface between dissimilar materials. [Solution] The method for manufacturing a molded object involves extruding a molding material from a nozzle and layering it to form a three-dimensional molded object, and includes a first step of extruding a first molding material from a nozzle, and a second step of extruding a second molding material, which is a different molding material from the first molding material, onto the first molding material from the nozzle, wherein in at least one of the first and second steps, the nozzle temperature for melting the target molding material is set higher than the reference temperature.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a shaped article. [Background Art]

[0002] Patent Document 1 discloses a three-dimensional additive manufacturing apparatus that includes an extrusion head for extruding heat-melted modeling material from a nozzle, and forms a three-dimensional object by stacking the modeling material extruded from the nozzle while moving the extrusion head. This three-dimensional additive manufacturing apparatus has a heating unit fixed to the extrusion head that heats the area immediately below the nozzle, and by heating the area immediately below the nozzle using the heating unit, it improves the strength of the lamination interface and reduces irregularities on the surface of the shaped article. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2017-100304 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] The present disclosure has been devised in view of the above-described conventional situation, and an object of the present disclosure is to provide a method for manufacturing a shaped article that can improve adhesive strength at an interface between different materials. [Means for Solving the Problem]

[0005] The present disclosure provides a method for manufacturing a shaped article in which a modeling material is discharged from a nozzle and stacked to form a three-dimensional shaped article, the method including: a first step of discharging a first modeling material from the nozzle; and a second step of discharging a second modeling material, which is a modeling material different from the first modeling material, from the nozzle onto the first modeling material, wherein in at least one of the first step and the second step, a nozzle temperature for melting the target modeling material is set higher than a reference temperature. [Effects of the Invention]

[0006] According to this disclosure, it is possible to improve the adhesive strength at the interface between dissimilar materials. [Brief explanation of the drawing]

[0007] [Figure 1] Block diagram showing an example of the configuration of a molding apparatus used in the molding method according to Embodiment 1. [Figure 2] A diagram illustrating the reference temperature in the method for manufacturing molded objects according to Embodiment 1. [Figure 3] Conceptual diagram showing an example of a method for manufacturing a molded object according to Embodiment 1. [Figure 4] A schematic diagram showing a laminate in the process of being manufactured by the manufacturing method of the 3D object according to Embodiment 1 (the entire filament is heated to a temperature higher than the reference temperature). [Figure 5] A schematic diagram showing a laminate in the process of being manufactured by the manufacturing method of the first embodiment (only the interface layer is heated at a temperature higher than the reference temperature). [Figure 6] A schematic diagram (a combination of Figures 4 and 5) showing a laminate in the process of being manufactured by the manufacturing method of the shaped object according to Embodiment 1. [Figure 7] A graph comparing the molding method according to Embodiment 1 with a conventional method. [Figure 8] A graph comparing the molding method according to Embodiment 1 with a conventional method. [Modes for carrying out the invention]

[0008] (Background leading to this disclosure) Typically, 3D printers, which are devices for manufacturing three-dimensional objects, extrude a material from a nozzle and build up layers of the extruded material to form a three-dimensional object. During the manufacturing of this three-dimensional object, the material extruded from the nozzle is layered on top of the previous layer, adhering to it. However, when different materials are stacked, the adhesive strength at the interface tends to weaken due to differences in the physical or chemical properties of each material. For this reason, the device described in Patent Document 1 is equipped with a heating unit in the extrusion head and uses the heating unit to heat the area directly below the nozzle in order to improve the adhesive strength at the interface. However, the manufacturing method for objects described in Patent Document 1 requires a device with a heating unit and cannot be implemented using existing or off-the-shelf equipment.

[0009] Therefore, in the following embodiment, a method for manufacturing molded objects that can improve the adhesive strength at the interface between dissimilar materials using existing or off-the-shelf equipment will be described.

[0010] The following describes in detail each embodiment of the method for manufacturing molded objects according to this disclosure, with reference to the drawings as appropriate. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0011] (Embodiment 1) <Configuration of a 3D printing machine> The following describes an example of the configuration of the molding apparatus 1 used in the molding method according to Embodiment 1, with reference to Figure 1. Figure 1 is a block diagram showing an example of the configuration of the molding apparatus 1 used in the molding method according to Embodiment 1.

[0012] The molding device 1 is a pre-built device. Therefore, the configuration shown in Figure 1 is just one example, and one part may be divided into multiple parts, or multiple parts may be combined into one. Also, the configuration shown in Figure 1 is just one example, and some parts may be omitted or other parts may be added as needed. Furthermore, the links and arrows for each part shown in Figure 3 show an example of data transmission and reception, but the connection configuration is not limited to this, and other connections and linkages may be made.

[0013] The 3D object manufacturing apparatus 1 comprises a control unit 10, a model data transmission unit 11, a filament changer 12, an extruder 13, a printer head 14, a print bed 15, and a bed heater 16. Under the control of the control unit 10, the 3D object manufacturing apparatus 1 forms a three-dimensional object by extruding and layering molten filament F (modeling material) from the nozzle 20 of the printer head 14 onto the print bed 15. The filament F is a thermoplastic resin.

[0014] The control unit 10 is responsible for controlling each part of the object manufacturing apparatus 1. It is configured using, for example, a Central Processing Unit (CPU) or a Field Programmable Gate Array (FPGA), and works in cooperation with a memory unit (not shown) to perform various processes and controls. Specifically, the control unit 10 refers to the programs and data held in the memory unit (not shown) and executes those programs to realize the various functions of the object manufacturing apparatus 1.

[0015] The model data transmission unit 11 is the part that transmits three-dimensional model data to the control unit 10. Specifically, the model data transmission unit 11 acquires three-dimensional model data generated from software such as slicing software via a recording medium such as a USB memory or a communication interface such as Wi-Fi, and transmits it to the control unit 10.

[0016] The filament exchanger 12 is a part that automatically exchanges filament F. The filament exchanger 12 replaces filament F when filament F is used up or when changing the type of filament F.

[0017] The extruder 13 is a part that draws the filament F held by the filament exchanger 12 into the printer head 14 and supplies it. The extruder 13 has a configuration in which a pair of rollers 13a and 13b are adjacent to each other (see FIG. 3), and conveys the filament F set between the pair of rollers 13a and 13b by rotating the rollers 13a and 13b.

[0018] The printer head 14 is a part that heats and melts the filament F supplied from the extruder 13, discharges the molten filament F from the nozzle 20, and laminates the discharged filament F on the print bed 15 to form a modeled object. Under the control of the control unit 10, the printer head 14 discharges the filament F to a designated position while moving in a horizontal direction or a vertical direction via a drive motor (not shown) or the like. The printer head 14 includes a nozzle 20, a nozzle heater 21, and a cooling fan 22.

[0019] The nozzle 20 is a part that melts the filament F and discharges the molten filament F through a discharge port 20a (see FIG. 3).

[0020] The nozzle heater 21 is a part that heats the nozzle 20 to melt the filament F. The nozzle heater 21 normally heats the nozzle 20 at a reference temperature (see description below), and heats the nozzle 20 at a temperature higher than the reference temperature at a predetermined timing (see description below). It should be noted that the heating temperature of the nozzle heater 21 herein is equal to the nozzle temperature. That is, the nozzle temperature in a normal state is the reference temperature, and the nozzle temperature at the predetermined timing is higher than the reference temperature.

[0021] The cooling fan 22 is responsible for cooling the filament F that is extruded from the nozzle 20 and layered on the print bed 15. The cooling fan 22 can be switched on / off or its airflow adjusted under the control of the control unit 10.

[0022] The print bed 15 is the base portion on which the filament F extruded from the nozzle 20 is layered. The print bed 15 is movable vertically via a drive motor (not shown) or the like under the control of the control unit 10. The bottom layer of filament F extruded from the nozzle 20 adheres to the print bed 15, supporting the layered structure in a stable position during the manufacturing of the three-dimensional object.

[0023] The bed heater 16 is a part that heats the print bed 15 to maintain a constant temperature.

[0024] <Reference temperature> The reference temperature will be explained below with reference to Figure 2. Figure 2 is a diagram illustrating the reference temperature in the molding manufacturing method according to Embodiment 1.

[0025] The reference temperature is the temperature at which the filament F falls linearly from the nozzle 20 without clogging near the nozzle's extrusion port 20a and without interruption. The reference temperature can be rephrased as a recommended temperature set by, for example, the manufacturer of the 3D printing apparatus 1 or the manufacturer of the filament F, taking into account the apparatus configuration, ambient temperature, type of filament F, etc.

[0026] If the nozzle temperature is below the reference temperature, the filament F may not reach its melting temperature, resulting in insufficient melting and clogging near the nozzle's outlet 20a. Furthermore, clogging near the nozzle's outlet 20a and insufficient melting of the filament F can increase its viscosity, preventing smooth extrusion of the filament F from the nozzle 20. As a result, the extrusion of the filament F from the nozzle 20 may become intermittent, or the filament F may deform irregularly, becoming bent or wavy when extruded from the nozzle 20.

[0027] If the nozzle temperature is excessively high compared to the reference temperature, the filament F may carbonize and accumulate near the nozzle's discharge opening 20a, causing a blockage. As a result, the extrusion of filament F from the nozzle 20 may become intermittent, or the filament F may not be extruded linearly from the nozzle 20. Also, if the nozzle temperature is excessively high compared to the reference temperature, the filament F may melt excessively in the extruder 13, changing its physical properties (making the filament F softer). This may prevent the rollers 13a and 13b from firmly gripping the filament F, resulting in an insufficient supply of filament F from the extruder 13 to the nozzle 20. Consequently, the extrusion of filament F from the nozzle 20 may become intermittent, or the filament F may not be extruded linearly from the nozzle 20.

[0028] On the other hand, in this disclosure, the nozzle temperature is raised above the reference temperature at a predetermined timing. However, if the nozzle temperature is excessively higher than the reference temperature, the aforementioned problems may occur. Therefore, even at temperatures higher than the reference temperature in this disclosure, it is necessary to satisfy the same conditions as at the reference temperature: the filament F does not clog near the discharge port 20a of the nozzle 20 and falls in a straight line from the nozzle 20 without interruption. A specific example of a temperature higher than the reference temperature here is a temperature that is 10°C to 20°C higher than the reference temperature (reference temperature + 10 to 20°C). However, it goes without saying that the appropriate range will differ depending on the type of filament F.

[0029] <Basic operation of 3D printing equipment> The following describes the basic operation of the 3D printing apparatus 1.

[0030] The 3D modeling apparatus 1 acquires three-dimensional model data via the model data transmission unit 11 and transmits it to the control unit 10. The control unit 10 controls each part based on the acquired three-dimensional model data and starts the printing process. In addition, the control unit 10 turns on the nozzle heater 21, cooling fan 22, and bed heater 16 when starting the printing process.

[0031] First, the filament changer 12 selects the filament F to be used and supplies it to the extruder 13. Next, the extruder 13 draws the filament F into the printer head 14 and pushes it into the nozzle 20. Then, the filament F melts inside the nozzle 20, which is heated by the nozzle heater 21.

[0032] Subsequently, the molten filament F is extruded from the nozzle 20's extrusion port 20a, and the extruded filament F is stacked on the print bed 15. At this time, the print bed 15 is kept at an appropriate temperature by the bed heater 16, so the bottom layer of the stacked filament F (the layer in contact with the print bed 15) is properly adhered to the print bed 15.

[0033] In this way, the control unit 10 moves the printer head 14 and the print bed 15 in accordance with the progress of printing, thereby forming a three-dimensional object.

[0034] <Manufacturing method of modeled object> The following describes an example of a method for manufacturing a molded object, with reference to Figures 3 to 6. Figure 3 is a conceptual diagram showing an example of a method for manufacturing a molded object according to Embodiment 1. Figure 4 is a schematic diagram showing a laminate in the process of being manufactured, formed by the method for manufacturing a molded object according to Embodiment 1 (the entire filament F is heated at a temperature higher than the reference temperature). Figure 5 is a schematic diagram showing a laminate in the process of being manufactured, formed by the method for manufacturing a molded object according to Embodiment 1 (only the interface layer is heated at a temperature higher than the reference temperature). Figure 6 is a schematic diagram showing a laminate in the process of being manufactured, formed by the method for manufacturing a molded object according to Embodiment 1 (a combination of Figures 4 and 5).

[0035] The method for manufacturing a molded object according to this disclosure repeats the process of extruding filament F from the nozzle 20, based on the basic operation of the molded object manufacturing apparatus 1 described above. In this way, the molded object manufacturing apparatus 1 stacks the filament F layer by layer (see Figures 4-6). This is also called the "lamination process".

[0036] Specifically, the method for manufacturing a molded object according to this disclosure, as shown in Figure 3, comprises a first step of extruding filament F1 (corresponding to the "first molding material") from a nozzle 20, and a second step of extruding filament F2 (corresponding to the "second molding material") onto filament F1.

[0037] Here, filament F1 is either a rigid material or a flexible material, and filament F2 is the other of the rigid and flexible materials. Rigid materials include, for example, PLA (Poly Lactic Acid) or ABS (Acrylonitrile Butadiene Styrene). Flexible materials include, for example, TPU (Thermoplastic Polyurethane).

[0038] In each of the aforementioned steps, it is important to set the temperature to increase the adhesive strength at the interface between filament F1 and filament F2. For this reason, in the molding method of this disclosure, in at least one of the first and second steps, the nozzle is heated by the nozzle heater 21 to a temperature higher than the reference temperature. This is because at least one of filament F1 and filament F2 is sufficiently melted, improving the fluidity of the filament in question. As a result, both filament F1 and filament F2 are cooled and solidified in a diffused and intertwined state at the interface, thus increasing the adhesive strength at the interface between filament F1 and filament F2.

[0039] In other words, the method for manufacturing the molded object described herein can be implemented in one of the following three patterns: [1] to [3]. [1] In the first step, the filament F1 is heated to a temperature higher than the reference temperature (see Figures 4(c) and 4(d); in the second step, the nozzle temperature is the reference temperature). [2] In the second step, the filament F2 is heated to a temperature higher than the reference temperature (see Figures 4(a) and 4(b); in the first step, the nozzle temperature is the reference temperature). [3] In the first step, filament F1 is heated to a temperature higher than the reference temperature, and in the second step, filament F2 is heated to a temperature higher than the reference temperature (see Figures 4(e) and (f)).

[0040] Furthermore, the method for manufacturing a molded object according to this disclosure may also involve heating only the interface layer at a temperature higher than the reference temperature, based on any of the above [1] to [3] (see Figure 5). Here, the term "interface layer" as used herein refers to a layer formed by filament F1 that is in contact with the interface between filament F1 (first molding material) and filament F2 (second molding material), or a layer formed by filament F2 that is in contact with the aforementioned interface.

[0041] Furthermore, the method for manufacturing a molded object according to this disclosure may include a mixture of cases based on any of the above [1] to [3], where the entire target filament F is heated to a temperature higher than the reference temperature, and cases where only the interface layer of the target filament F is heated to a temperature higher than the reference temperature (see Figure 6).

[0042] Furthermore, in the additive manufacturing process including the first and second steps of the present disclosure, the cooling fan 22 may be stopped or slowed down when the nozzle temperature is raised above the reference temperature (see below).

[0043] Incidentally, when the extrusion speed of the filament F from the nozzle 20 increases, the force with which the extruder 13 pushes the filament F into the nozzle 20 also increases. On the other hand, even when the nozzle temperature is higher than the reference temperature (reference temperature + 10 to 20°C), the physical properties of the filament F may change in the extruder 13 (the filament F becomes softer). In this case, if the extrusion speed is high, the rollers 13a and 13b may not be able to firmly grip the filament F, and the extruder 13 may not be able to adequately supply the filament F to the nozzle 20. For this reason, in the method for manufacturing molded objects of this disclosure, the extrusion speed when the nozzle temperature is higher than the reference temperature may be slower than the extrusion speed when the nozzle temperature is at the reference temperature. Note that the extrusion speed referred to here is roughly equivalent to the layering speed.

[0044] <Comparison with conventional methods> The following comparison will be made between the manufacturing method of the object according to this disclosure and the conventional method, with reference to Figures 7 and 8. Figure 7 is a graph comparing the manufacturing method of the object according to Embodiment 1 and the conventional method. Figure 8 is a graph comparing the manufacturing method of the object according to Embodiment 1 and the conventional method.

[0045] Figures 7 and 8 illustrate how the temperature of the filament F, which constitutes a predetermined layer, changes at a specific point during the printing process. Specifically, in Figure 7(A), it can be seen that the temperature of the filament F extruded from the nozzle 20 decreases due to the ambient air or the cooling fan 22. In Figure 7(B), it can be seen that the temperature of the filament F constituting the predetermined layer increases as the next layer is stacked on top of the predetermined layer. In Figure 7(c), it can be seen that the temperature of the filament F constituting the predetermined layer increases as yet another layer is stacked on top of the predetermined layer. Based on the above, it can be seen that after the filament F is extruded from the nozzle 20, it cools rapidly due to the ambient air or the cooling fan 22, causing its temperature to drop sharply. Then, as the next layer approaches, it is heated and its temperature rises slightly. This cycle is repeated many times, resulting in a decrease in the overall temperature increase.

[0046] As shown in Figures 7 and 8, when the nozzle temperature is higher than the reference temperature (the manufacturing method of the object according to this disclosure), it can be confirmed that the filament F extruded from the nozzle 20 maintains a higher temperature compared to when the nozzle temperature is at the reference temperature (conventional method). Therefore, the manufacturing method of the object according to this disclosure has higher adhesive strength between adjacent layers compared to the conventional method.

[0047] Furthermore, as shown in Figure 7, when the nozzle temperature is higher than the reference temperature and the cooling fan 22 is off, it can be confirmed that the filament F extruded from the nozzle 20 maintains a higher temperature compared to when the nozzle temperature is higher than the reference temperature and the cooling fan 22 is on. For this reason, it is preferable to stop or slow down the cooling fan 22, especially when the nozzle temperature is higher than the reference temperature, during the lamination process.

[0048] Furthermore, as shown in Figure 8, it can be confirmed that when the filament F is made of a soft material, the filament F extruded from the nozzle 20 maintains a higher temperature compared to when the filament F is made of a hard material.

[0049] Furthermore, referring to Figures 7 and 8, it can be seen that the temperature of the filament F extruded from the nozzle 20 decreases until the next layer is stacked. For this reason, heating filament F2 at a nozzle temperature higher than the reference temperature allows the filament to be maintained at a higher temperature than heating filament F1 at a nozzle temperature higher than the reference temperature. In other words, the method for manufacturing molded objects according to this disclosure is preferred in the order of [3], [2], and [1] above.

[0050] Furthermore, taking into account the matters mentioned above, in the example shown in Figure 4, the order (e), (f), (a), (b), (d), (c) is preferable. Similarly, in the example shown in Figure 5, the order (c), (f), (a), (d), (e), (b) is preferable.

[0051] As described above, the method for manufacturing molded objects according to Embodiment 1 can improve the adhesive strength at the interface between dissimilar materials.

[0052] (Other variations) Although various embodiments have been described above with reference to the drawings, it goes without saying that this disclosure is not limited to these examples. It will be clear to those skilled in the art that various modifications, alterations, substitutions, additions, deletions, and equivalents can occur within the scope of the claims, and these will naturally fall within the technical scope of this disclosure. Furthermore, the components of the various embodiments described above can be combined arbitrarily without departing from the spirit of the invention.

[0053] (Note) The following technologies are disclosed based on the above description of embodiments.

[0054] <Technology 1> A method for manufacturing a three-dimensional object, wherein a molding material (filament F) is extruded from a nozzle 20 and layered to form a three-dimensional object, A first step of extruding a first molding material (filament F1) from the nozzle 20, The process includes a second step of extruding a second molding material (filament F2), which is a different molding material from the first molding material (filament F1), from the nozzle 20 onto the first molding material (filament F1), In at least one of the first and second steps, the nozzle temperature for melting the target molding material (filament F) is raised to a reference temperature. Modeled object manufacturing method.

[0055] This configuration ensures that at least one of the first and second molding materials is sufficiently melted, improving the fluidity of the material in question. As the two materials cool and solidify while diffusing and intertwining at the interface, the adhesive strength at the interface between the first and second molding materials increases. In other words, this configuration improves the adhesive strength at the interface between dissimilar materials. As a result, delamination and cracking at the interface between the first and second molding materials, i.e., the interface between dissimilar materials, can be suppressed, leading to superior mechanical strength and durability of the molded object.

[0056] <Technology 2> The aforementioned reference temperature is, The temperature at which the molding material (filament F) falls linearly from the nozzle 20 without clogging near the extrusion port 20a of the nozzle 20 and without interruption along the way. The method for manufacturing the molded object described in Technical 1.

[0057] This configuration ensures that the fluidity of the molding material is properly maintained, allowing for stable extrusion of the molding material from the nozzle.

[0058] <Technology 3> In the second step, the nozzle temperature for melting the second molding material (filament F2) is raised to a higher temperature than the reference temperature. A method for manufacturing a molded object as described in Technology 1 or Technology 2.

[0059] This configuration increases the adhesive strength at the interface between the first and second molding materials compared to the case where the first molding material is heated at a nozzle temperature higher than the reference temperature.

[0060] <Technology 4> The second molding material (filament F2) is a soft material. A method for manufacturing a molded object as described in any one of the three technologies described in Technology 1 to Technology 3.

[0061] With this configuration, when a second, soft material is laminated onto a first, flexible material, the flexibility of the second material is utilized, making it easier to fill gaps at the interface with the first material and improving adhesion at this interface.

[0062] <Technology 5> In at least one of the first and second steps, only the interface layer between the first molding material (filament F1) and the second molding material (filament F2) is heated at a nozzle temperature higher than the reference temperature. A method for manufacturing a molded object as described in any one of the technologies 1 through 4.

[0063] This configuration ensures that the interface layer of the target material is sufficiently melted, thereby further improving the adhesion between the first and second materials. Furthermore, this configuration allows only the interface layer of the target material to be heated at a nozzle temperature higher than the reference temperature, thus maintaining the fluidity of the target material and enabling stable extrusion of the material from the nozzle.

[0064] <Technology 6> The first discharge speed when the nozzle temperature is higher than the reference temperature is reduced compared to the second discharge speed when the nozzle temperature is at the reference temperature. A method for manufacturing a molded object as described in any one of the technologies 1 through 5.

[0065] This configuration prevents the printing material from breaking or tearing in the extruder, and allows for stable ejection of the printing material from the nozzle.

[0066] <Technology 7> In at least one of the first and second steps, in which the nozzle temperature is raised higher than the reference temperature, the cooling fan 22 that cools the extruded molding material (filament F) is stopped or slowed down. A method for manufacturing a molded object as described in any one of the techniques 1 through 6.

[0067] This configuration prevents the extruded molding material from cooling rapidly, thus maintaining the fluidity of the molding material. [Industrial applicability]

[0068] This disclosure is useful as a method for manufacturing molded objects that can improve the adhesive strength at the interface between dissimilar materials. [Explanation of symbols]

[0069] 1 Modeled object manufacturing equipment 10 Control Unit 11 Model data transmission unit 12 Filament changer 13 Extruder 13a, 13b Laura 14 Printer head 15 Print Bed 16 Bed heater 20 nozzles 20a outlet 21 Nozzle Heater 22 Cooling Fans F, F1, F2 filaments

Claims

1. A method for manufacturing a three-dimensional object by extruding a molding material from a nozzle and layering it, A first step of extruding a first molding material from the nozzle, The process includes a second step of extruding a second molding material, which is a molding material different from the first molding material, from the nozzle onto the first molding material. In at least one of the first and second steps, the nozzle temperature for melting the target molding material is raised to a reference temperature. Modeled object manufacturing method.

2. The aforementioned reference temperature is, The temperature at which the molding material falls linearly from the nozzle without clogging near the nozzle's discharge port and without interruption is such that the material does not clog the nozzle's outlet. The method for manufacturing a molded object according to claim 1.

3. In the second step, the nozzle temperature for melting the second molding material is raised to a higher temperature than the reference temperature. The method for manufacturing a molded object according to claim 1.

4. The second molding material is a soft material. The method for manufacturing a molded object according to claim 1.

5. In at least one of the first and second steps, only the interface layer between the first molding material and the second molding material is heated at a nozzle temperature higher than the reference temperature. The method for manufacturing a molded object according to claim 1.

6. The first discharge speed when the nozzle temperature is higher than the reference temperature is reduced compared to the second discharge speed when the nozzle temperature is at the reference temperature. The method for manufacturing a molded object according to claim 1.

7. In at least one of the first and second steps, in which the nozzle temperature is raised higher than the reference temperature, the cooling fan that cools the extruded molding material is stopped or slowed down. The method for manufacturing a molded object according to claim 1.

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