Three-dimensional modeling methods

Abstract

To provide a three-dimensional molding method capable of suppressing generation of interlayer separation between slice layers whose heat-shrinkage ratios are different from each other.SOLUTION: In a three-dimensional molding method for molding a three-dimensional molded article by using a first material containing a first resin and a second material containing a second resin having a heat-shrinkage ratio different from the heat-shrinkage ratio of the first resin, when a first slice layer formed of one of the first material and the second material is overlaid with a second slice layer formed of the other of the first material and the second material, a first boundary layer formed of the one is laminated on the first slice layer, and a second boundary layer formed of the other is laminated on the first boundary layer, and the second slice layer is laminated on the second boundary layer, and the first boundary layer is, when the first boundary layer is seen from a lamination direction of the first slice layer and the second slice layer, a layer in which a plurality of gaps are formed inside an outline of the first boundary layer.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This invention relates to a three-dimensional shaping method.

Background Art

[0002] Research and development have been carried out on a three-dimensional shaping apparatus that shapes a three-dimensional object by laminating a shaping material in which at least a part is melted.

[0003] Regarding this, as a three-dimensional shaping method of laminating a shaping material with a high thermal shrinkage rate such as POM (Polyoxymethylene) on a stage to shape a three-dimensional object, when laminating the shaping material on the stage, at least one of the temperature of the stage and the ambient temperature is controlled, so that the laminated shaping material is prevented from peeling off from the stage. There is a known three-dimensional shaping method (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the three-dimensional shaping method described in Patent Document 1, when laminating a plurality of shaping materials with different thermal shrinkage rates on a stage to shape a three-dimensional object, among the plurality of shaping materials, the layer formed by the shaping material with a higher thermal shrinkage rate and the plurality of shaping materials In some cases, it has been difficult to suppress the occurrence of delamination at the boundary with the layer formed by the shaping material with a lower thermal shrinkage rate.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the present invention is a three-dimensional molding method for molding a three-dimensional object using a first material containing a first resin and a second material containing a second resin having a different thermal shrinkage rate than the first resin, wherein when a second slice layer formed by the other of the first and second materials is laminated onto a first slice layer formed by one of the first and second materials, a first boundary layer formed by the one is laminated on the first slice layer, a second boundary layer formed by the other is laminated on the first boundary layer, and a second slice layer is laminated on the second boundary layer, wherein the first boundary layer is a layer in which a plurality of voids are formed inside the contour of the first boundary layer when viewed from the lamination direction of the first and second slice layers. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of the configuration of the three-dimensional modeling apparatus 1. [Figure 2] This figure shows an example of the hardware configuration of the control device 60. [Figure 3] This figure shows an example of the functional configuration of the control device 60. [Figure 4] This figure shows an example of the processing flow in which the control device 60 performs molding control. [Figure 5] This figure shows an example of the appearance of the three-dimensional object ML1. [Figure 6] This is a top view showing an example of the appearance of the first part P1. [Figure 7] This is a top view showing an example of the appearance of the first boundary layer B1. [Figure 8] This is a top view showing an example of the appearance of the second boundary layer B2. [Figure 9] This figure shows an example of how a portion of the second boundary layer B2 impregnates into multiple voids formed in the first boundary layer B1. [Figure 10]This figure shows an example of how a portion of the second boundary layer B2 impregnates into the void in the first boundary layer B1 when the thickness of the build path of the second boundary layer B2 is greater than the thickness of the void in the first boundary layer B1 in the direction in which the void extends. [Figure 11] This figure shows an example of how a portion of the second boundary layer B2 impregnates into the voids of the first boundary layer B1 when the thickness of the build path of the second boundary layer B2 is greater than the thickness of the build path of the first boundary layer B1. [Figure 12] This is a top view showing an example of the appearance of the bottommost second slice layer P21 of the three second slice layers stacked as the second part P2. [Figure 13] This is a top view showing an example of the appearance of the middle second slice layer P22, one of three second slice layers stacked as the second part P2. [Figure 14] This is a top view showing an example of the appearance of the uppermost second slice layer P23, one of three second slice layers stacked as the second part P2. [Figure 15] This figure shows an example of the appearance of the three-dimensional object ML2. [Figure 16] This figure shows an example of the appearance of the three-dimensional object ML3. [Figure 17] This figure shows an example of the appearance of a three-dimensional object ML4. [Figure 18] This figure shows an example of the appearance of the ML5 three-dimensional object. [Modes for carrying out the invention]

[0008] <Embodiment> Embodiments of the present invention will be described below with reference to the drawings.

[0009] <Overview of 3D printing equipment> First, an overview of the three-dimensional molding apparatus according to this embodiment will be described.

[0010] The three-dimensional shaping device according to the embodiment shapes a three-dimensional object using a first material and a second material. The first material includes a first resin. The second material includes a second resin having a heat shrinkage rate different from that of the first resin. Further, the three-dimensional shaping device includes a stage, a discharge unit, a moving unit, and a control unit. The discharge unit discharges each of the first material and the second material. The moving unit relatively moves the discharge unit and the stage. The control unit controls the discharge unit and the moving unit. Further, when the control unit laminates a second slice layer formed of the other of the first material and the second material on a first slice layer formed of one of the first material and the second material, the control unit laminates a first boundary layer formed of the one on the first slice layer, laminates a second boundary layer formed of the other on the first boundary layer, and laminates the second slice layer on the second boundary layer. And the first boundary layer is a layer in which a plurality of voids are formed inside the contour of the first boundary layer when the first boundary layer is viewed from the lamination direction of the first slice layer and the second slice layer. Thereby, the three-dimensional shaping device can suppress the occurrence of delamination at the boundary between the first slice layer and the second slice layer formed of materials having different heat shrinkage rates.

[0011] Hereinafter, the configuration of the three-dimensional shaping device according to the embodiment, the configuration of the control device included in the three-dimensional shaping device, and the processing performed by the control device will be described in detail.

[0012] <Configuration of the three-dimensional shaping device> Hereinafter, the configuration of the three-dimensional shaping device according to the embodiment will be described by taking the three-dimensional shaping device 1 as an example.

[0013] FIG. 1 is a diagram showing an example of the configuration of the three-dimensional shaping device 1.

[0014] Here, the three-dimensional coordinate system TC is a three-dimensional Cartesian coordinate system that indicates the direction in the diagram in which the three-dimensional coordinate system TC is drawn. For the sake of explanation, the X-axis in the three-dimensional coordinate system TC will be simply referred to as the X-axis. Similarly, for the sake of explanation, the Y-axis in the three-dimensional coordinate system TC will be simply referred to as the Y-axis. Similarly, for the sake of explanation, the Z-axis in the three-dimensional coordinate system TC will be simply referred to as the Z-axis. Furthermore, as an example, the case in which the negative direction of the Z-axis coincides with the direction of gravity will be explained below. For this reason, for the sake of explanation, the positive direction of the Z-axis will be referred to as the upward direction or simply as up, and the negative direction of the Z-axis will be referred to as the downward direction or simply as down.

[0015] The three-dimensional molding apparatus 1 comprises an extrusion unit 10 having a nozzle Nz, a stage 20 having a molding surface 21 on which a three-dimensional object is molded, a moving unit 30, a heating unit 40, a temperature detection unit 50, a control device 60, and a data generation device 70. In the three-dimensional molding apparatus 1, the control device 60 may be configured integrally with the data generation device 70. Alternatively, the three-dimensional molding apparatus 1 may be configured without the data generation device 70. In this case, the data generation device 70 is connected to the control device 60 of the three-dimensional molding apparatus 1 so as to be able to communicate from the outside. Alternatively, the three-dimensional molding apparatus 1 may be configured without the control device 60 and the data generation device 70. In this case, the control device 60 is connected to the three-dimensional molding apparatus 1 so as to be able to communicate from the outside. Also, in this case, the data generation device 70 is connected to the control device 60 so as to be able to communicate from the outside.

[0016] The three-dimensional printing apparatus 1 extrudes a printing material X (not shown) from the extrusion unit 10 toward the printing surface 21 of the stage 20, while changing the relative position between the extrusion unit 10 and the stage 20. In this way, the three-dimensional printing apparatus 1 creates a three-dimensional object of a predetermined shape by stacking N slice layers L. Here, N can be any integer greater than or equal to 1. In this case, the first slice layer L from the bottom of the N slice layers L is stacked on the printing surface 21. Each of the N slice layers L stacked on the printing surface 21 is a layer of printing material X extruded along a printing path parallel to the printing surface 21. The printing path is the scanning path of the nozzle Nz as it moves while extruding the printing material X relative to the stage 20. In other words, the three-dimensional printing apparatus 1 extrudes the printing material X by the extrusion unit 10 along the printing path of the nth slice layer L out of N slice layers L, and stacks the nth slice layer L on top of the (n-1)th slice layer L. Here, n is any integer between 1 and N. Furthermore, each of the N slice layers L may consist of a single layer or multiple stacked layers. Here, the printing path of a certain slice layer L includes an outline path, which is the scanning path of the nozzle Nz along the contour of the slice layer L, and an infill path, which is the scanning path of the nozzle Nz within the region enclosed by the outline path. That is, a certain slice layer L is composed of the printing material X extruded along the outline path of the slice layer L and the printing material X extruded along the infill path of the slice layer L.

[0017] Furthermore, the three-dimensional molding apparatus 1 can selectively extrude two types of materials, a first material and a second material, which have different thermal shrinkage rates, from the nozzle Nz as molding material X. This allows the three-dimensional molding apparatus 1 to fabricate three-dimensional objects made from these two types of materials. Here, the first material is a material containing a first resin. The second material is a material containing a second resin having a different thermal shrinkage rate than the first resin. Below, as an example, we will describe the case where the thermal shrinkage rate of the second material is greater than that of the first material. In this case, the first resin is, for example, ABS (Acrylonitrile Butadiene Styrene). In this case, the second resin is, for example, POM (Polyoxymethylene). Note that the first resin may be another type of resin having a thermal shrinkage rate smaller than that of the second resin, instead of ABS. Furthermore, the second resin may be other types of resins having a greater thermal shrinkage rate than the first resin, instead of POM. For example, crystalline resins such as PA12 (polyamide 12), PBT (polybutylene terephthalate), PSU (polysulfone), PA66 (polyamide 66), PET (polyethylene terephthalate), LCP (liquid crystal polymer), PEEK (polyether ether ketone), PSF (polysulfone), PA6 (polyamide 6), PPS (polyphenylene sulfide), etc.

[0018] The three-dimensional printing apparatus 1 performs printing control for creating such three-dimensional objects based on three-dimensional printing data. Here, the three-dimensional printing apparatus 1 generates three-dimensional printing data in response to the received operation. The three-dimensional printing data is data for stacking N slice layers L on the three-dimensional printing apparatus 1 as a three-dimensional object of a predetermined shape. The three-dimensional printing apparatus 1 stores shape data that represents the said shape. The shape data can be any data that represents the said shape, for example, STL (Stereolithography) data. Based on the received operation and the shape data, the three-dimensional printing apparatus 1 generates object data that represents at least a virtual object including the virtual object, which is a virtual object having the shape indicated by the shape data and a virtual support attached to the object to support the object. The object is the part of the N slice layers L that are stacked and separated from the N slice layers L to form a single three-dimensional object. Furthermore, the support is the portion of the stacked N slice layers L that supports the molded object.

[0019] After generating object data, the 3D printing apparatus 1 stores the generated object data. After storing the object data, the 3D printing apparatus 1 virtually slices the object into N slice layers VL based on the slice condition information. Each of the N slice layers VL that the object is virtually sliced ​​into by the 3D printing apparatus 1 corresponds to each of the aforementioned N slice layers L. For the sake of explanation, in the following, the nth slice layer VL among these N slice layers VL will be referred to as slice layer VLn, and the nth slice layer L among the aforementioned N slice layers L will be referred to as slice layer Ln. In this case, for example, the first slice layer VL1 corresponds to the first slice layer L1. Here, the slice condition information is information that indicates the slice conditions for virtually slicing the object indicated by the object data stored by the 3D printing apparatus 1 into N slice layers VL. The slice condition information includes information indicating the number of N slice layers VL, information indicating the thickness of each of the N slice layers VL, etc., as information indicating the slice conditions.

[0020] After virtually slicing the object, the 3D printing apparatus 1 generates a printing path for each of the N sliced ​​layers VL based on the printing path generation condition information. As mentioned above, the printing path is the scanning path of the nozzle Nz moving while extruding the printing material X to the stage 20. Therefore, the printing material X extruded along the printing path of the nth slice layer VLn is the actual slice layer Ln that corresponds to slice layer VLn.

[0021] Here, the nth slice layer VLn is one of the slice layers from which at least one of the printed body and the support contained in the object has been sliced. Therefore, the nth slice layer VLn contains at least one of the sliced ​​portion of the printed body and the sliced ​​portion of the support. In other words, the nth slice layer VLn contains at least one of the sliced ​​layer of the printed body and the sliced ​​layer of the support. The sliced ​​layers of the printed body are classified into two types: the first solid layer and the build layer. The first solid layer is the solid layer of the printed body. The printed body is composed of the first solid layer and the build layer which is stacked between the first solid layer and the first solid layer. In other words, the printed body is created by stacking the first solid layer and the build layer. The sliced ​​layers of the support are classified into three types: the second solid layer, the support layer, and the raft layer. The second solid layer is the solid layer of the support. The raft layer is the base layer upon which the first solid layer, build layer, second solid layer, and support layer are stacked. The support is composed of the second solid layer, the support layer stacked between the second solid layers, and the raft layer. In other words, the support is formed by stacking the second solid layer, the support layer, and the raft layer. For example, if the shape of a certain object has an overhang, the overhang portion of the object is supported by such a support. From the above, the type of the nth slice layer VLn is classified by the layers contained in the nth slice layer VLn. For example, if the nth slice layer VLn contains only the first solid layer, the type of the nth slice layer VLn is the first solid layer. Furthermore, for example, if the nth slice layer VLn contains a first solid layer and a second solid layer, the type of the nth slice layer VLn is represented by the combination of the type of layer from which the printed object was sliced ​​among the layers contained in the nth slice layer VLn and the type of layer from which the support was sliced ​​among the layers contained in the nth slice layer VLn, that is, the combination of the first solid layer and the second solid layer. And the type of the nth slice layer VLn is also the type of the nth slice layer Ln.Therefore, the three-dimensional molding apparatus 1 can identify the type of the nth slice layer VLn and the type of slice layer Ln based on the slice condition information.

[0022] After generating the build path for each of the N slice layers VL, the three-dimensional printing apparatus 1 generates three-dimensional printing data that includes build path information indicating the build path for each of the generated N slice layers VL. Here, the build path generation condition information is information that indicates the build path generation conditions for generating the build path for each of the N slice layers VL. The build path generation condition information includes information that indicates the shape of the build path for each type of N slice layer VL, information that indicates the width of the build path for each type of N slice layer VL, information that indicates the thickness of the build path for each type of N slice layer VL, information that indicates the movement speed of the nozzle Nz when extruding the build material X along the build path for each type of N slice layer VL, and information that indicates the type of build material X extruded from the nozzle Nz, as information that indicates the build path generation conditions. Furthermore, the build path information indicating a particular build path includes other information such as information indicating the width of the build path, information indicating the thickness of the build path, and information indicating the movement speed of the nozzle Nz when the build material X is extruded along the build path.

[0023] In the three-dimensional printing apparatus 1, the aforementioned slice condition information may or may not include information indicating the type of the (n-1)th slice layer VLn-1 among the N slice layers VL, and information indicating the type of the nth slice layer VLn that is stacked on top of the (n-1)th slice layer VLn-1 among the N slice layers VL.

[0024] Here, the raft layer L, one of the N slice layers L, is a layer formed between the build surface 21 and the other layers as a base for the slice layers L of the other layers, and is a layer filled with build material X. The other layers are the individual slice layers L that are stacked on top of the raft layer among the N slice layers L, and specifically refer to some or all of the slice layers L of the first solid layer, build layer, second solid layer, and support layer. When the other layers are stacked on the build surface 21 so as to be in contact with the build surface 21, they may become difficult to peel off from the build surface 21. Also, in this case, the other layers may not be able to be fixed with good accuracy. Furthermore, residual stress may remain in the other layers. To solve these problems, the raft layer L is a layer that is stacked between the other layers and the build surface 21. Furthermore, each slice layer L of the solid layer, build layer, and support layer is formed by an outline, which is the build material X extruded along a predetermined outer shape contour, and an infill, which is the build material X extruded within the area enclosed by the outline. In other words, each slice layer L of the solid layer, build layer, and support layer is formed by an outline, which is the build material X extruded along the aforementioned outline path, and an infill, which is the build material X extruded along the aforementioned infill path. The slice layer L of the solid layer is a layer in which the area enclosed by the outline of the slice layer L of the solid layer is filled almost completely with infill. In other words, the slice layer L of the solid layer is a layer in which the infill filling rate within that area is 100%. It can also be said that the slice layer L of the first solid layer is one or more layers containing the build material X that form the surface of the build object. Furthermore, the slice layer L of the build layer is one or more layers containing the build material X that form the interior of the build object. Furthermore, the slice layer L of the second solid layer can be rephrased as one or more layers containing the molding material X that forms the surface of the support. On the other hand, the slice layer L of the molding layer is a layer in which infill is included within the region enclosed by the outline of the molding layer, and in which there are regions within that region that are not filled with infill.In other words, the slice layer L of the build layer is a layer in which the infill filling rate within that region is less than 100%. Alternatively, the slice layer L of the build layer can be rephrased as one or more layers containing the build material X that forms the interior of the build object. Furthermore, the slice layer L of the support layer is a layer in which the infill is contained within the region enclosed by the outline of the support layer, and there are regions within that region that are not filled with infill. In other words, the slice layer L of the support layer is a layer in which the infill filling rate within that region is less than 100%. Furthermore, the slice layer Ln of the support layer can be rephrased as one or more layers containing the build material X that forms the interior of the support.

[0025] The three-dimensional molding apparatus 1 performs molding control to fabricate a three-dimensional object based on the three-dimensional molding data generated as described above. Furthermore, when the three-dimensional molding apparatus 1 stacks N slice layers L on the molding surface 21 during molding control, each of the N slice layers L is extruded onto the molding surface 21 by the extrusion unit 10 as a slice layer L of a type represented by some or all of the raft layer, first solid layer, molding layer, second solid layer, and support layer, thereby stacking the N slice layers L to fabricate one three-dimensional object.

[0026] In this case, when a slice layer L formed by a first material and a slice layer L formed by a second material are laminated, delamination may occur at the boundary between these two slice layers due to the difference in thermal shrinkage rates between the first material and the second material.

[0027] Therefore, in the manufacturing control for creating a three-dimensional object, the three-dimensional molding apparatus 1, when stacking a second slice layer on a first slice layer, stacks a first boundary layer formed of the first material on top of the first slice layer, stacks a second boundary layer formed of the second material on top of the first boundary layer, and stacks a second slice layer on top of the second boundary layer. Here, the boundary layer refers to two slice layers L located so as to sandwich the boundary between the slice layer L formed of the first material and the slice layer L formed of the second material, which are among the N slice layers stacked on the manufacturing surface 21 by the three-dimensional molding apparatus 1. Furthermore, the first boundary layer is a boundary layer formed of the first material, and is a boundary layer in which multiple voids are formed inside the contour when viewed from the stacking direction between the first slice layer and the second slice layer. Furthermore, the second boundary layer is a boundary layer formed by the second material, and is a boundary layer that partially impregnates into the multiple voids formed in the first boundary layer. Also, the first slice layer is each of the slice layers L formed by the first material, excluding the first boundary layer. Furthermore, the second slice layer is each of the slice layers L formed by the second material, excluding the second boundary layer.

[0028] Thus, the three-dimensional molding apparatus 1 can suppress delamination at the boundary between the first and second slice layers by stacking the first and second slice layers in the order of first slice layer, first boundary layer, second boundary layer, and second slice layer, sandwiching the first and second boundary layers between them. This is achieved by a combination of three requirements: the first slice layer and the first boundary layer have the same thermal shrinkage rate; the second slice layer and the second boundary layer have the same thermal shrinkage rate; and a portion of the second boundary layer impregnates the multiple voids formed in the first boundary layer. When a portion of the second boundary layer impregnates the multiple voids formed in the first boundary layer, the second boundary layer fits into the first boundary layer. As a result, the first boundary layer supports the compressive stress that causes the second boundary layer to warp due to the decrease in temperature. Consequently, the occurrence of warping in the second boundary layer is suppressed, and the second boundary layer becomes less likely to separate from the first boundary layer. This method of laminating slice layers L allows the three-dimensional molding apparatus 1 to suppress delamination at the boundary between the first slice layer and the second slice layer, which are formed from materials with different thermal shrinkage rates. When a portion of the second boundary layer is impregnated into the first boundary layer in this manner, the interlayer adhesion between the second boundary layer and the first boundary layer is higher compared to when the first boundary layer is formed using the first and second materials separately, and then the second boundary layer is laminated on top of the first boundary layer. This is because when the first boundary layer is formed using the first and second materials separately, and then the second boundary layer is laminated on top of the first boundary layer, a layer interface is formed between the second material in the first boundary layer and the second material in the second boundary layer. In contrast, when a portion of the second boundary layer is impregnated into the voids of the first boundary layer, no layer interface is formed between the second material impregnated into the first boundary layer and the second material in the second boundary layer. Therefore, the process of impregnating a portion of the second boundary layer into the voids of the first boundary layer and the process of forming the first boundary layer with the first and second materials respectively, and then laminating the second boundary layer on top of the first boundary layer, are fundamentally different processes. Furthermore, it is preferable that the thermal shrinkage volume of the second boundary layer during molding is 60% or less of the thermal shrinkage volume of the second boundary layer after molding is complete. This suppresses a decrease in molding accuracy due to changes in the shape of the molded layer during molding.

[0029] The extrusion unit 10 is an extrusion device that selectively extrudes a first material and a second material as molding material X onto the molding surface 21. More specifically, the extrusion unit 10, along with the nozzle Nz described above, has a first material melting unit that melts one or more types of material to make a first material, a second material melting unit that melts one or more types of material to make a second material, a material supply switching unit, a first material supply unit, and a second material supply unit. In the extrusion unit 10, the first material supply unit and the first material melting unit are connected by a first supply passage. Also in the extrusion unit 10, the second material supply unit and the second material melting unit are connected by a second supply passage. Furthermore, the first material melting unit and the material supply switching unit are connected by a third supply passage. Furthermore, the second material melting unit and the material supply switching unit are connected by a fourth supply passage. Furthermore, the material supply switching unit and the nozzle Nz are connected by a communication hole. The material supply switching unit switches the material supplied to the nozzle Nz as molding material X via the communication hole between the first material supplied from the first material melting unit and the second material supplied from the second material melting unit. The nozzle Nz extrudes the molding material X supplied from the material supply switching unit through the communication hole from its tip. The discharge unit 10 may be configured to have two nozzles instead of nozzle Nz: a first nozzle that extrudes the first material and a second nozzle that extrudes the second material. In this case, the discharge unit 10 does not have a material supply switching unit. In this case, the first material melting unit is connected to the first nozzle via the first communication hole. In this case, the second material melting unit is connected to the second nozzle via the second communication hole.

[0030] Here, when the three-dimensional molding apparatus 1 stacks the nth slice layer Ln on top of the n-1th slice layer Ln-1, it changes at least one of the width of the molding material X extruded onto the top surface of the n-1th slice layer Ln-1 and the thickness of the molding material X extruded onto the top surface of the n-1th slice layer Ln-1 by changing the distance between the top surface of the n-1th slice layer Ln-1 and the tip of the nozzle Nz. However, the maximum width of the molding material X extruded onto the top surface of the nth slice layer Ln by the three-dimensional molding apparatus 1 is the outer diameter of the tip of the nozzle Nz. This is because if the distance between the top surface of the n-1th slice layer Ln-1 and the tip of the nozzle Nz is made shorter than the inner diameter of the tip of the nozzle Nz, the molding material X extruded from the tip of the nozzle Nz will be compressed by the tip of the nozzle Nz as it is extruded onto the top surface of the n-1th layer.

[0031] The first material supply unit contains one or more materials in the form of pellets, powder, etc., as the first material. Below, as an example, we will describe the case in which the material contained in the first material supply unit includes a pelletized first resin. The first material supply unit is composed of, for example, a hopper. The material contained in the first material supply unit is supplied to the first material melting unit via a first supply passage provided below the first material supply unit.

[0032] The second material supply unit contains one or more materials in the form of pellets, powder, etc., as the second material. Below, as an example, we will describe the case in which the material contained in the second material supply unit includes pelletized second resin. The second material supply unit is composed of, for example, a hopper. The material contained in the second material supply unit is supplied to the second material melting unit via a second supply passage provided below the second material supply unit.

[0033] The first material melting section comprises a screw case, a flat screw housed within the screw case, a drive motor for driving the flat screw, and a barrel fixed below the flat screw within the screw case.

[0034] A flat screw is a screw with a flattened cylindrical shape, in which a spiral groove is formed on the bottom surface of the cylinder, extending from the outer circumference towards the central axis of the cylinder.

[0035] The barrel is provided with a third supply channel. The barrel also has a built-in heater. The heater temperature is controlled by the control device 60.

[0036] The material supplied between the rotating flat screw and the barrel is melted, at least partially, by the rotation of the flat screw and heating by a heater built into the barrel, becoming a fluid, paste-like first material. The paste-like first material is supplied to the material supply switching unit via a third supply passage provided in the barrel by the rotation of the flat screw. When the state of the material supply switching unit is switched to a state in which the first material is supplied to the nozzle Nz, the first material supplied to the material supply switching unit is supplied to the nozzle Nz via a communication hole. The first material supplied to the nozzle Nz is then extruded as molding material X from the tip of the nozzle Nz toward the stage 20.

[0037] The second material melting section has the same configuration as the first material melting section. Therefore, a detailed explanation of the second material melting section will be omitted below. The second material, which has been made into a paste in the second material melting section, is supplied to the material supply switching section via a fourth supply passage provided in the barrel by the rotation of a flat screw. When the state of the material supply switching section is switched to a state in which the second material is supplied to the nozzle Nz, the second material supplied to the material supply switching section is supplied to the nozzle Nz via a communication hole. The second material supplied to the nozzle Nz is then extruded as molding material X from the tip of the nozzle Nz toward the stage 20.

[0038] The moving unit 30 changes the relative position between the nozzle Nz of the discharge unit 10 and the stage 20. More specifically, the moving unit 30 changes the relative position between the nozzle Nz of the discharge unit 10 and the stage 20 by moving either the discharge unit 10 or the stage 20, or both. Below, as an example, a case in which the moving unit 30 changes the relative position between the nozzle Nz of the discharge unit 10 and the stage 20 by moving the stage 20 will be described. For example, the moving unit 30 includes a first moving mechanism 31 that moves the discharge unit 10 along the Z axis, and a second moving mechanism 32 that moves the stage 20 along the X axis and Y axis relative to the discharge unit 10. In this embodiment, the first moving mechanism 31 shown in Figure 1 is composed of a lifting device that moves the discharge unit 10 along the Z axis, and has a motor for moving the discharge unit 10 along the Z axis. The second moving mechanism 32 shown in Figure 1 is composed of a horizontal transport device that moves the stage 20 along the X and Y axes, and has a motor for moving the stage 20 along the X axis and a motor for moving the stage 20 along the Y axis. The first moving mechanism 31 and the second moving mechanism 32 are controlled by the control device 60.

[0039] The heating unit 40 heats the target area containing the molding material X extruded by the extrusion unit 10. Here, the target area is the area on the molding surface 21 that includes the entirety of the N slice layers L when N slice layers L are stacked on the molding surface 21 as a single three-dimensional object. The heating unit 40 can have any configuration as long as it is capable of heating the target area. In the example shown in Figure 1, the heating unit 40 is a flat panel heater that has the upper surface of the stage 20, i.e., the surface facing the molding surface 21, and heats the target area. In this case, the heating unit 40 heats the area sandwiched between the lower surface of the flat heating unit 40 and the molding surface 21 as the target area. The heating unit 40 is controlled by the control device 60. Also, in the example shown in Figure 1, the heating unit 40 is provided with a through hole through which the nozzle Nz is inserted. Therefore, the heating unit 40 is provided around the nozzle Nz and moves together with the nozzle Nz. The heating unit 40 may be a chamber-type heater that blows hot air instead of a panel heater, a cartridge heater, or any other type of heater capable of heating the area to be heated. Furthermore, the three-dimensional molding apparatus 1 may be configured without a heating unit 40.

[0040] The temperature detection unit 50 is a temperature sensor that detects the temperature of the upper surface of the slice layer L stacked on the molding surface 21. In the example shown in Figure 1, the temperature detection unit 50 is located on the lower surface of the heating unit 40. The temperature detection unit 50 then outputs information indicating the detected temperature to the control device 60. Alternatively, the three-dimensional molding apparatus 1 may be configured without the temperature detection unit 50.

[0041] The control device 60 controls the entire three-dimensional molding apparatus 1. The control device 60 acquires the three-dimensional molding data generated by the data generation device 70 via a network or recording medium. The control device 60 manufactures a three-dimensional object by executing a pre-stored three-dimensional molding program and performing molding control that controls the operation of the ejection unit 10 and the moving unit 30 according to the three-dimensional molding data. Note that the control device 60 may be composed of a combination of multiple circuits rather than a computer.

[0042] The aforementioned molding control refers to the control of the extrusion unit 10 and the movement unit 30. More specifically, the molding control refers to the control of creating a single three-dimensional object of a predetermined shape by stacking N slice layers L on the molding surface 21. Here, the nth slice layer Ln of the N slice layers L is stacked on top of the (n-1)th slice layer Ln-1. When the nth slice layer Ln is stacked on top of the (n-1)th slice layer Ln, the heat of the nth slice layer Ln melts a part of the (n-1)th slice layer Ln-1. As a result, the nth slice layer Ln is joined to the (n-1)th slice layer Ln-1. Consequently, on the molding surface 21, the N slice layers L are stacked as a single three-dimensional object. Therefore, in this embodiment, the 0th slice layer L0 refers to the molding surface 21. That is, in this embodiment, the 1st slice layer L1 is stacked on top of the 0th slice layer L0, i.e., the molding surface 21.

[0043] When the nth slice layer Ln is to be stacked on top of the (n-1)th slice layer Ln-1 by the build control, the control device 60 controls the ejection unit 10 and the movement unit 30, and the ejection unit 10 ejects the build material X along the build path of the nth slice layer VLn corresponding to the nth slice layer Ln. In this way, the control device 60 can stack the nth slice layer Ln on top of the (n-1)th slice layer Ln-1. By performing the above control as build control, the control device 60 sequentially ejects the build material X, stacking N slice layers L on the build surface 21 to create one three-dimensional object.

[0044] Furthermore, in the process of controlling the molding process, when the second slice layer is stacked on the first slice layer, the control device 60 stacks the first boundary layer on top of the first slice layer, stacks the second boundary layer on top of the first boundary layer, and stacks the second slice layer on top of the second boundary layer, as described above. This allows the control device 60 to suppress the occurrence of delamination at the boundary between the first slice layer and the second slice layer, which are formed from materials with different thermal shrinkage rates.

[0045] Figure 2 shows an example of the hardware configuration of the control device 60.

[0046] The control device 60 comprises a processor 61, a storage unit 62, an input receiving unit 63, a communication unit 64, and a display unit 65. As mentioned above, the control device 60 may be an information processing device configured separately from the three-dimensional molding apparatus 1. In this case, the three-dimensional molding apparatus 1 is connected to this information processing device for communication and is controlled by this information processing device.

[0047] The processor 61 is, for example, a CPU (Central Processing Unit). However, the processor 61 may also be another type of processor, such as an FPGA (Field Programmable Gate Array). Furthermore, the processor 61 may be composed of multiple processors. The processor 61 implements various functions of the control device 60 by executing various programs, instructions, etc., stored in the storage unit 62.

[0048] The storage unit 62 includes HDD (Hard Disk Drive), SSD (Solid State Drive), EEPROM (Electrically Erasable Programmable Read Only Memory), ROM (Read Only Memory), RAM (Random Access Memory), etc. Note that the storage unit 62 may be an external storage device connected via a digital input / output port such as USB (Universal Serial Bus) instead of being built into the control device 60. The storage unit 62 stores various programs, instructions, and information processed by the control device 60. For example, the storage unit 62 stores data for three-dimensional modeling.

[0049] The input receiving unit 63 accepts user operations performed while viewing the image displayed on the display unit 65. The input receiving unit 63 is an input device including, for example, a keyboard, mouse, or touchpad. The input receiving unit 63 may also be a touch panel integrated with the display unit 65.

[0050] The communication unit 64 is comprised of, for example, digital input / output ports such as USB, and Ethernet (registered trademark) ports.

[0051] The display unit 65 displays an image. The display unit 65 is a display device that includes, for example, a liquid crystal display panel, an organic EL (ElectroLuminescence) display panel, etc., as a display provided by the control device 60.

[0052] Figure 3 shows an example of the functional configuration of the control device 60.

[0053] The control device 60 includes a storage unit 62, an input receiving unit 63, a communication unit 64, a display unit 65, and a control unit 66.

[0054] The control unit 66 controls the entire control device 60. The control unit 66 includes a device control unit 661. These functional units of the control unit 66 are realized, for example, by the processor 61 executing various programs stored in the memory unit 62. Some or all of these functional units may be hardware functional units such as LSIs (Large Scale Integration) or ASICs (Application Specific Integrated Circuits).

[0055] The device control unit 661 controls the entire three-dimensional molding apparatus 1. For example, the device control unit 661 controls the ejection unit 10, the moving unit 30, and the heating unit 40, respectively.

[0056] The data generation device 70 is a device that generates three-dimensional modeling data used by the three-dimensional modeling device 1 to create three-dimensional objects. The data generation device 70 generates three-dimensional modeling data in the same way as the three-dimensional modeling device 1 generates three-dimensional modeling data as described above. For this reason, the explanation of this method will be omitted here. The data generation device 70 also stores the shape data described above in accordance with the received operation. The data generation device 70 may or may not be capable of generating shape data. If the data generation device 70 is not capable of generating shape data, the data generation device 70 acquires shape data from another device via a network or storage medium. The data generation device 70 also stores the slice condition information and modeling path generation condition information described above in accordance with the received operation.

[0057] The data generation device 70 is, for example, an information processing device such as a workstation, desktop PC (Personal Computer), notebook PC, tablet PC, multifunction mobile phone terminal (smartphone), mobile phone terminal, or PDA (Personal Digital Assistant), but is not limited to these. More specifically, the data generation device 70 is composed of a computer equipped with one or more processors, memory, and an input / output interface for inputting and outputting signals to and from the outside.

[0058] <Processing performed by the control device to control the molding process> The following describes the process by which the control device 60 performs molding control, with reference to Figure 4. Figure 4 is a diagram showing an example of the flow of the process by which the control device 60 performs molding control. In the following, as an example, we will describe the case in which the three-dimensional molding data is stored in the storage unit 62 at a timing prior to the processing of step S110 shown in Figure 4. In addition, in the following, as an example, we will describe the case in which the control device 60 receives an operation to start molding control at that timing. In addition, in the following, as an example, we will describe the case in which the three-dimensional object that the three-dimensional molding device 1 molds according to the processing of the flowchart shown in Figure 4 is the three-dimensional object ML1 shown in Figure 5. Figure 5 is a diagram showing an example of the appearance of the three-dimensional object ML1. The three-dimensional object ML1 is a roughly rectangular three-dimensional object in which a second part P2, which is formed in a rectangular shape by stacking one or more second slice layers, is stacked on a first part P1, which is formed in a rectangular shape by stacking one or more first slice layers. The three-dimensional object ML1 is, for example, one of the parts of a device such as a printer. In the three-dimensional object ML1, for example, a sliding member is placed on top of the second part P2. In this case, the three-dimensional object ML1 receives the sliding of the member from the second part P2, which is formed of a second material such as POM with a low coefficient of friction, so wear on the first part P1 due to the sliding of the member can be suppressed. When the three-dimensional printing device 1 attempts to print a three-dimensional object ML1 in which a second part P2 formed of a second material is laminated onto a first part P1 formed of a first material, as shown in Figure 5, it laminates a first boundary layer B1 on top of the first part P1, a second boundary layer B2 on top of the first boundary layer B1, and a second part P2 on top of the second boundary layer B2. As a result, the three-dimensional molding apparatus 1 can suppress the occurrence of delamination at the boundary between the first part P1 and the second part P2, which are formed from materials with different thermal shrinkage rates, that is, at the boundary between the first slice layer and the second slice layer.

[0059] After the control device 60 receives an operation to start the molding control, the device control unit 661 reads the three-dimensional molding data that has been previously stored in the storage unit 62 from the storage unit 62 (step S110).

[0060] Next, the device control unit 661 starts the fabrication of the first part P1 based on the three-dimensional fabrication data read in step S110 (step S120).

[0061] Next, the device control unit 661 waits until the molding of the first part P1, which was started in step S120, is completed (step S130). In Figure 4, the process in step S130 is indicated by "Complete?". Here, the device control unit 661 determines, for example, whether the molding of the first part P1 is completed based on the three-dimensional molding data read in step S110. The device control unit 661 may determine whether the molding of the first part P1 is completed by any method.

[0062] Here, Figure 6 is a top view showing an example of the appearance of the first part P1. In the example shown in Figure 6, the first part P1 is formed by one first slice layer. In this example, the outline OL1 of the first slice layer forming the first part P1 is fabricated by the 3D 3D printer 1 extruding the first material along the build path PH1, which is shown in Figure 6 from the starting point S1 to the ending point G1. In this example, the infill IF1 of the first slice layer forming the first part P1 is fabricated by the 3D 3D printer 1 extruding the first material along the build path PH2, which is shown in Figure 6 from the starting point S2 to the ending point G2. In Figure 6, the build paths PH1 and PH2 are indicated by dotted arrows. In Figure 6, the hatched areas indicate the areas where the first material has been extruded. That is, in this example, the infill IF1 is 100%. Therefore, in this example, the first slice layer forming the first portion P1 is the first solid layer. The first portion P1 may also be formed by stacking multiple first slice layers. In this case, these multiple first slice layers may include a molded layer in addition to the first solid layer.

[0063] If the device control unit 661 determines that the fabrication of the first part P1, which was started in step S120, has been completed (step S130-YES), it stacks the first boundary layer B1 on top of the first part P1 (step S140).

[0064] Here, Figure 7 is a top view showing an example of the appearance of the first boundary layer B1. In the example shown in Figure 7, the first boundary layer B1 is formed by one slice layer L. However, it is desirable that the first boundary layer B1 be formed by two or more slice layers L. This is because it is possible to increase the depth of each of the multiple voids formed in the first boundary layer B1, making it easier for the second boundary layer B2 to impregnate each of these multiple voids. For example, the first boundary layer B1 may be fabricated by stacking five slice layers L. In this case, the three-dimensional fabrication apparatus 1 can, for example, make the thickness of the first boundary layer B1 about 1 cm. As a result, the depth of the second boundary layer that impregnates the voids becomes deeper, and the length over which the second boundary layer and the first boundary layer fit together can be increased.

[0065] In the example shown in Figure 7, the outline OL2 of the first boundary layer B1 is fabricated by the extrusion of the first material by the 3D printing device 1 along the build path PH3, which runs from the starting point S3 to the ending point G3, as shown in Figure 7. In this example, the infill IF2 of the first boundary layer B1 is fabricated by the extrusion of the first material by the 3D printing device 1 along the build path PH4, which runs from the starting point S4 to the ending point G4, as shown in Figure 7. In Figure 7, the build paths PH3 and PH4 are indicated by dotted arrows. In Figure 7, the hatched areas indicate the areas where the first material was extruded. In other words, in this example, the infill IF2 is less than 100%. In this case, as shown in Figure 7, multiple voids are formed in the first boundary layer B1 according to the infill IF2 infill rate. In order to fit the second boundary layer B2 into the first boundary layer B1, the infill IF2 should have a filling rate within the range of 20% to 90%. If the infill IF2 filling rate is within the range of 30% to 80%, the second boundary layer B2 will fit more reliably into the first boundary layer B1. The device control unit 661 can change the infill IF2 filling rate by, for example, separating adjacent infill paths in the infill path for forming the infill IF2 by a predetermined distance. In other words, the device control unit 661 can change the infill IF2 filling rate by separating the molding paths PH4 by a predetermined distance. For example, in experiments conducted by the applicant, when the predetermined interval was approximately 1 / 4 the width of the molding path of the infill IF2, the infill IF2 filling rate was approximately 20%. The correspondence between the predetermined interval and the infill IF2 filling rate can be determined by prior experiments, various theoretical calculations, etc. Furthermore, the distance considered optimal as a predetermined interval may be determined by prior experiments or by other methods. Such other methods include, for example, a method based on the correlation between the ratio of the inner diameter of the nozzle Nz to the longitudinal length of the infill IF2 and the strength of the fit of the second boundary layer B2 to the first boundary layer B1. Here, the longitudinal direction of the infill IF2 is the direction in which the length of the build path PH4 is longer of the two directions in which the build path PH4 extends.In other words, in this example, the longitudinal direction of the infill IF2 is parallel to the Y-axis. When using this method, it is necessary to obtain such correlations through prior experiments or other means. Furthermore, when using this method, the convenience can be improved by creating a table of such correlations. In this example, the first boundary layer B1 has seven voids that extend in a direction parallel to the Y-axis. In this example, the filling rate of the infill IF2 is approximately 45%. Note that the device control unit 661 may be configured to form the first boundary layer B1 by other methods. For example, the device control unit 661 may be configured to stack the first boundary layer B1, which has an infill IF2 with multiple voids formed at random positions, on top of the first part P1.

[0066] Furthermore, in the example shown in Figure 7, the longitudinal direction of infill IF2 is parallel to the longitudinal direction of infill IF1 of the first part P1. The longitudinal direction of infill IF1 is the direction in which the length of the build path PH2 of infill IF1 is longer than the direction in which the build path PH2 of infill IF1 extends. However, the device control unit 661 may be configured to laminate the first boundary layer B1 on the first part P1 such that these two longitudinal directions intersect. In this case, the three-dimensional molding apparatus 1 can improve the interlayer adhesion between the first part P1 and the first boundary layer B1.

[0067] Furthermore, the device control unit 661 may be configured to control the heating unit 40 so that the temperature of the first boundary layer B1 when forming the first boundary layer B1 is higher than the temperature of the first part P1 when forming the first part P1. This allows the three-dimensional molding apparatus 1 to suppress the cooling of the second boundary layer B2 by the first boundary layer B1 when the second boundary layer B2 is laminated on top of the first boundary layer B1 in step S150, which will be described later. As a result, the three-dimensional molding apparatus 1 can more reliably suppress delamination at the boundary between the first boundary layer B1 and the second boundary layer B2. The method for heating the first boundary layer B1 by the heating unit 40 to achieve this may be a known method or a method to be developed in the future.

[0068] After the process in step S140 is completed, the device control unit 661 stacks the second boundary layer B2 on top of the first boundary layer B1 fabricated in step S140 (step S150).

[0069] Here, Figure 8 is a top view showing an example of the appearance of the second boundary layer B2. As shown in Figure 8, the second boundary layer B2 is formed by a single slice layer L. This is because if the second boundary layer B2 is made thicker, the degree of thermal shrinkage of the second boundary layer B2, which is formed by the second material having a larger thermal shrinkage rate than the first material, will increase, and there is a higher possibility that the second boundary layer B2 will delaminate from the first boundary layer B1 as the temperature decreases.

[0070] In the example shown in Figure 8, the outline OL3 of the second boundary layer B2 is formed by the extrusion of the second material by the three-dimensional molding apparatus 1 along the build path PH5, which runs from the starting point S5 to the ending point G5, as shown in Figure 8. In the same example, the infill IF3 of the second boundary layer B2 is formed by the extrusion of the second material by the three-dimensional molding apparatus 1 along the build path PH6, which runs from the starting point S6 to the ending point G6, as shown in Figure 8. In Figure 8, the build paths PH5 and PH6 are indicated by dotted arrows. In Figure 8, the hatched areas indicate the areas where the second material was extruded. The apparatus control unit 661, for example, separates adjacent infill paths for forming the infill IF3 by a predetermined second distance. In other words, the apparatus control unit 661 separates the build paths PH6 by a predetermined second distance. As a result, the 3D printing apparatus 1 can reduce the infill IF3 filling rate to less than 100%, thereby reducing the degree of deformation of the second boundary layer B2 due to thermal shrinkage. This is because the higher the infill IF3 filling rate, the greater the degree of thermal shrinkage of the second boundary layer B2 formed by the second material, which has a higher thermal shrinkage rate than the first material, and the higher the possibility that the second boundary layer B2 will peel off from the first boundary layer B1 as the temperature decreases. The predetermined second interval may be the same as the predetermined interval, or it may be a different interval from the predetermined interval.

[0071] Furthermore, the longitudinal direction of infill IF3 intersects with the longitudinal direction of infill IF2 of the first boundary layer B1. In the example shown in Figure 8, the longitudinal direction in which infill IF3 of the second boundary layer B2 extends is perpendicular to the longitudinal direction in which infill IF2 of the first boundary layer B1 extends. Here, the longitudinal direction of infill IF3 is the direction of the longer of the two directions in which the build path PH6 extends. That is, in this example, the longitudinal direction of infill IF3 is parallel to the X-axis. As a result, the three-dimensional molding apparatus 1 can more reliably impregnate a portion of the second boundary layer B2 into the multiple voids formed in the first boundary layer B1. Here, Figure 9 shows an example of how a portion of the second boundary layer B2 is impregnated into the multiple voids formed in the first boundary layer B1. Furthermore, Figure 9 is a cross-sectional view obtained by cutting the first portion P1, the first boundary layer B1, and the second boundary layer B2 at the cross-section AA shown in Figures 6 to 8, respectively. Note that the thicknesses of the first portion P1, the first boundary layer B1, and the second boundary layer B2 shown in Figure 9 are depicted as different from the thicknesses of the first portion P1, the first boundary layer B1, and the second boundary layer B2 shown in Figure 5, in order to clearly show the impregnation of a portion of the second boundary layer B2 into the multiple voids formed in the first boundary layer B1. As shown in Figure 9, when the second boundary layer B2 is laminated on top of the first boundary layer B1, a portion of the second boundary layer B2 impregnates into the multiple voids formed in the first boundary layer B1. As a result, the second boundary layer B2 and the first boundary layer B1 fit together. Consequently, the three-dimensional molding apparatus 1 can suppress the occurrence of delamination at the boundary between the first boundary layer B1 and the second boundary layer B2.

[0072] Furthermore, the device control unit 661 may configure the second boundary layer B2 to be laminated on top of the first boundary layer B1 such that the longitudinal direction of the infill IF3 of the second boundary layer B2 is parallel to the longitudinal direction of the infill IF2 of the first boundary layer B1. However, in this case, it may become difficult for a portion of the second boundary layer B2 to impregnate the multiple voids formed in the first boundary layer B1, or it may become too easy for a portion of the second boundary layer B2 to impregnate the multiple voids formed in the first boundary layer B1. If it becomes difficult for a portion of the second boundary layer B2 to impregnate the multiple voids formed in the first boundary layer B1, the second boundary layer B2 and the first boundary layer B1 may become difficult to fit together and may easily peel off from the first boundary layer B1. On the other hand, if a portion of the second boundary layer B2 becomes too easily impregnated into the multiple voids formed in the first boundary layer B1, the second boundary layer B2 will have difficulty forming a slice layer L on the first boundary layer B1, resulting in a higher likelihood of manufacturing defects. To prevent this, when the device control unit 661 stacks the second boundary layer B2 on the first boundary layer B1 so that these two longitudinal directions are parallel, it makes the thickness of the manufacturing path of the second boundary layer B2 thicker than the thickness of the voids in the first boundary layer B1 in the direction in which the voids extend, or thicker than the thickness of the manufacturing path of the first boundary layer B1, as shown in Figures 10 and 11. As a result, even in this case, the three-dimensional printing apparatus 1 can suppress manufacturing defects in the second boundary layer B2 while making it easier for a portion of the second boundary layer B2 to impregnate into the multiple voids formed in the first boundary layer B1.

[0073] Here, Figure 10 shows an example of how a portion of the second boundary layer B2 impregnates into the void of the first boundary layer B1 when the thickness of the build path of the second boundary layer B2 is greater than the thickness of the void in the first boundary layer B1 in the direction in which the void extends. Build paths PT1 and PT2 shown in Figure 10 are examples of build paths for the first boundary layer B1. That is, in the example shown in Figure 10, the void between build path PT1 and build path PT2 is an example of a void in the first boundary layer B1. Also, build path PT3 shown in Figure 10 is an example of a build path for the second boundary layer B2. As shown in Figure 10, when the thickness of build path PT3 is greater than the thickness of the void between build path PT1 and build path PT2, a portion of build path PT3 impregnates into the void. On the other hand, in this case, the rest of the build path PT3 remains on top of the build paths PT1 and PT2. As a result, if the thickness of the build path of the second boundary layer B2 is greater than the thickness of the void in the first boundary layer B1 in the direction in which the void extends, it becomes less likely that defects will occur in the second boundary layer B2, and a portion of the second boundary layer B2 will be more easily impregnated into the multiple voids formed in the first boundary layer B1. In other words, the three-dimensional printing apparatus 1 can suppress defects in the second boundary layer B2 while making it easier for a portion of the second boundary layer B2 to be impregnated into the multiple voids formed in the first boundary layer B1.

[0074] On the other hand, Figure 11 shows an example of how a portion of the second boundary layer B2 impregnates into the voids of the first boundary layer B1 when the thickness of the build path of the second boundary layer B2 is greater than the thickness of the build path of the first boundary layer B1. The build path PT4 shown in Figure 11 is an example of the build path of the first boundary layer B1. That is, in the example shown in Figure 11, the voids on both sides of the build path PT4 are examples of the voids of the first boundary layer B1. Also, the build path PT5 shown in Figure 11 is an example of the build path of the second boundary layer B2. As shown in Figure 11, when the thickness of the build path PT5 is greater than the thickness of the build path PT4, a portion of the build path PT5 impregnates into the voids on both sides of the build path PT4. On the other hand, in this case, the rest of the build path PT5 remains on top of the build path PT4. As a result, when the thickness of the printing path for the second boundary layer B2 is greater than the thickness of the printing path for the first boundary layer B1, printing defects in the second boundary layer B2 become less likely, and a portion of the second boundary layer B2 becomes more easily impregnated into the multiple voids formed in the first boundary layer B1. In other words, the three-dimensional printing apparatus 1 can suppress the occurrence of printing defects in the second boundary layer B2 while facilitating the impregnation of a portion of the second boundary layer B2 into the multiple voids formed in the first boundary layer B1.

[0075] Furthermore, in the examples shown in Figures 5 and 9, when the first boundary layer B1 is viewed from the stacking direction of the first part P1 and the second part P2, the contour of the second boundary layer B2 is contained within the contour of the first boundary layer B1. That is, the device control unit 661 may be configured to fabricate the outline OL3 of the second boundary layer B2 in such a case that the outline OL3 of the second boundary layer B2 is contained within the outline OL2 of the first boundary layer B1. This is because, since there is no void in the first boundary layer B1 on the outline OL2, the second boundary layer B2 may peel off from the first boundary layer B1 due to thermal shrinkage of the second boundary layer B2. To suppress this, the three-dimensional molding apparatus 1 fabricates the outline OL3 in such a case that the outline OL3 is contained within the outline OL2. As a result, the three-dimensional molding apparatus 1 can impregnate a portion of the outline OL3 into the void formed in the first boundary layer B1, thereby suppressing the delamination of the second boundary layer B2 from the first boundary layer B1 on the outline OL2. In this case, when the apparatus control unit 661 forms the second boundary layer B2, it may configure the second boundary layer B2 to be thinner than the thickness of each of the second slice layers that form the second portion P2, which will be described later. As a result, the three-dimensional molding apparatus 1 can suppress the reduction in the dimensional accuracy of the three-dimensional molded object ML1 due to the thickness of the second boundary layer B2, which has a contour included inside the contour of the first boundary layer B1.

[0076] Here, when the device control unit 661 forms the second boundary layer B2, it may, for example, form the outline OL3 first and then the infill IF3. This is because, if the second material is a material such as POM, forming the infill IF3 first may result in failure to form the second boundary layer B2. In other words, this allows the three-dimensional molding apparatus 1 to easily form the second boundary layer B2.

[0077] Furthermore, when forming the outline OL3, the device control unit 661 may, for example, control the heating unit 40 to raise the temperature of the first boundary layer B1 to a higher temperature than when forming the infill IF3. This allows the three-dimensional molding apparatus 1 to improve the interlayer adhesion between the outline OL3 and the first boundary layer B1. As a result, the three-dimensional molding apparatus 1 can fabricate the infill IF3 while it is in contact with the outline OL3, thereby suppressing the occurrence of fabrication defects in the second boundary layer B2.

[0078] Furthermore, when forming the second boundary layer B2, the device control unit 661 may, for example, maintain the supply speed of the second material by the discharge unit 10 while slowing down the relative movement speed between the discharge unit 10 and the stage 20 using the movement unit 30, in order to promote the impregnation of a portion of the second boundary layer B2 into the multiple voids formed in the first boundary layer B1 as shown in Figure 9. In this case, the amount of the second material supplied per unit area when forming the second boundary layer B2 will be greater than the amount of the second material supplied per unit area when forming the second portion P2. As a result, the three-dimensional molding apparatus 1 can increase the amount of the second boundary layer B2 that is impregnated into the multiple voids. Consequently, the three-dimensional molding apparatus 1 can more reliably suppress delamination at the boundary between the first boundary layer B1 and the second boundary layer B2.

[0079] Furthermore, when forming the second boundary layer B2, the device control unit 661 may, for example, increase the supply speed of the second material by the discharge unit 10 while maintaining the relative movement speed between the discharge unit 10 and the stage 20 using the movement unit 30, in order to promote the impregnation of a portion of the second boundary layer B2 into the multiple voids formed in the first boundary layer B1 as shown in Figure 9. In this case as well, the amount of the second material supplied per unit area when forming the second boundary layer B2 will be greater than the amount of the second material supplied per unit area when forming the second portion P2. This also allows the three-dimensional molding apparatus 1 to increase the amount of the second boundary layer B2 that is impregnated into the multiple voids. As a result, the three-dimensional molding apparatus 1 can more reliably suppress the occurrence of delamination at the boundary between the first boundary layer B1 and the second boundary layer B2.

[0080] After the process in step S150 is completed, the device control unit 661 starts fabricating the second part P2 (step S160). In the following description, as an example, the case in which the second part P2 is a part of the three-dimensional fabricated object ML1 in which three rectangular parallelepiped second slice layers, second slice layer P21 to second slice layer P23, are stacked is explained. The second part P2 may also be a part of the three-dimensional fabricated object ML1 in which two or fewer second slice layers are stacked, or a part of the three-dimensional fabricated object ML1 in which four or fewer second slice layers are stacked.

[0081] Next, the device control unit 661 waits until the molding of the second part P2, which was started in step S160, is completed (step S170). In Figure 4, the process in step S170 is indicated by "Complete?". Here, the device control unit 661 determines, for example, whether the molding of the second part P2 is completed based on the three-dimensional molding data read in step S110. The device control unit 661 may determine whether the molding of the second part P2 is completed by any method.

[0082] Here, Figure 12 is a top view showing an example of the appearance of the bottommost second slice layer P21 of the three second slice layers stacked as the second part P2. In the example shown in Figure 12, the outline OL4 of the second slice layer P21 is fabricated by the extrusion of the second material by the 3D 3D printer 1 along the build path PH7, which goes from the starting point S7 to the ending point G7 as shown in Figure 12. In this example, the infill IF4 of the second slice layer P21 is fabricated by the extrusion of the second material by the 3D 3D printer 1 along the build path PH8, which goes from the starting point S8 to the ending point G8 as shown in Figure 12. In Figure 12, the build paths PH7 and PH8 are indicated by dotted arrows. Also in Figure 12, the hatched areas indicate the areas where the second material has been extruded. That is, in this example, the infill IF4 is less than 100%. The device control unit 661, for example, sets a predetermined third-degree separation between adjacent infill paths in the infill path for forming the infill IF4. In other words, the device control unit 661 sets a predetermined third-degree separation between, for example, the build paths PH8. This allows the three-dimensional molding apparatus 1 to achieve a filling rate of less than 100% for the infill IF4, and as a result, the degree of deformation due to thermal shrinkage of the second slice layer P21 can be reduced. This is because the higher the filling rate of the infill IF4, the greater the degree of thermal shrinkage of the second slice layer P21, and the compressive stress of the second slice layer P21 in response to the decrease in temperature generates tensile stress in the second boundary layer B2 at the interface with the first boundary layer B1, increasing the likelihood that the second boundary layer B2 will delaminate from the first boundary layer B1. For these reasons, the device control unit 661 sets the infill filling rate of the infill IF4 within the outline OL4 of the bottommost second slice layer P21 to the lowest filling rate among the infill filling rates within the outlines of each of the three second slice layers stacked on the second boundary layer B2. The predetermined third interval may be the same as at least one of the predetermined interval and the predetermined second interval, or it may be a different interval from both the predetermined interval and the predetermined second interval.Furthermore, if, for example, prior experiments have shown that there is little likelihood of the second boundary layer B2 delaminating from the first boundary layer B1, the device control unit 661 may be configured to set the infill filling rate within the outline of each of the three second slice layers stacked on top of the second boundary layer B2 to the lowest filling rate, except for the bottommost layer.

[0083] Furthermore, the longitudinal direction of infill IF4 intersects with the longitudinal direction of infill IF3 of the second boundary layer B2. In the example shown in Figure 12, the longitudinal direction of infill IF4 is perpendicular to the longitudinal direction of infill IF3. Here, the longitudinal direction of infill IF4 is the direction of the longer of the two directions in which the build path PH8 extends. That is, in this example, the longitudinal direction of infill IF4 is parallel to the Y-axis. As a result, the 3D printing apparatus 1 can improve the interlayer adhesion between the second slice layer P21 and the second boundary layer B2. That is, the 3D printing apparatus 1 can improve the interlayer adhesion between the second part P2 and the second boundary layer B2.

[0084] Furthermore, the device control unit 661 forms outline OL4 such that, when viewing the first boundary layer B1 from the stacking direction of the first part P1 and the second part P2, at least a portion of outline OL2 of the first boundary layer B1 and at least a portion of outline OL4 overlap. In the example shown in Figure 12, the device control unit 661 forms outline OL4 such that outline OL2 and outline OL4 overlap. This allows the three-dimensional molding apparatus 1 to suppress a decrease in the dimensional accuracy of the three-dimensional molded object ML1 due to the difference between the size of the contour of the first boundary layer B1 and the size of the contour of the second boundary layer B2.

[0085] The device control unit 661 stacks the second slice layer P21 on top of the second boundary layer B2, and then stacks the second slice layer P22 shown in Figure 13 on top of the second slice layer P21. Figure 13 is a top view showing an example of the appearance of the middle second slice layer P22, one of the three second slice layers stacked as the second portion P2. In the example shown in Figure 13, the outline OL5 of the second slice layer P22 is formed by the extrusion of the second material by the three-dimensional molding device 1 along the build path PH9, which goes from the starting point S9 to the ending point G9, as shown in Figure 13. In this example, the infill IF5 of the second slice layer P22 is formed by the extrusion of the second material by the three-dimensional molding device 1 along the build path PH10, which goes from the starting point S10 to the ending point G10, as shown in Figure 13. In Figure 13, the build path PH9 and the build path PH10 are indicated by dotted arrows. Furthermore, in Figure 13, the hatched areas indicate the areas where the second material was extruded. In other words, in this example, the filling rate of infill IF5 is less than 100%. The device control unit 661, for example, separates adjacent infill paths in the infill path for forming infill IF5 by a predetermined fourth interval. In other words, the device control unit 661 separates, for example, the build paths PH10 by a predetermined fourth interval. As a result, the three-dimensional molding apparatus 1 can reduce the filling rate of infill IF5 to less than 100%, and consequently, the degree of deformation of the second slice layer P22 due to thermal shrinkage can be reduced. This is because the higher the infill density of the infill IF5, the greater the degree of thermal shrinkage of the second slice layer P22. As the temperature decreases, the compressive stress on the second slice layer P22 generates tensile stress on the second slice layer P21 at the interface with the first boundary layer B1, increasing the likelihood that the second boundary layer B2 will delaminate from the first boundary layer B1 along with the second slice layer P21. Thus, in this example, the device control unit 661 gradually increases the infill density of the second slice layer as the fabrication progresses from the lower second slice layer to the upper second slice layer during the fabrication of the second portion P2. For this reason, the predetermined fourth interval is shorter than the predetermined third interval. Note that the predetermined fourth interval may be less than or equal to the predetermined third interval.

[0086] Furthermore, in the example shown in Figure 13, the longitudinal direction of infill IF5 is parallel to the longitudinal direction of infill IF4 of the second slice layer P21, but it may also be in a direction that intersects with the longitudinal direction of infill IF4. The longitudinal direction of infill IF5 is the direction in which the length of the build path PH10 is longer of the two directions in which the build path PH10 extends. When these two longitudinal directions intersect, the three-dimensional printing apparatus 1 can improve the interlayer adhesion between the second slice layer P21 and the second slice layer P22.

[0087] Furthermore, in the example shown in Figure 13, the device control unit 661 forms the outline OL5 such that, when viewed from the stacking direction of the first part P1 and the second part P2, the outline OL2 of the first boundary layer B1 and the outline OL5 of the second slice layer P22 overlap. As a result, the three-dimensional molding apparatus 1 can suppress the reduction in the dimensional accuracy of the three-dimensional molded object ML1 due to the difference in the size of the outline of the first boundary layer B1 and the size of the outline of the second boundary layer B2.

[0088] The device control unit 661 stacks the second slice layer P22 on top of the second slice layer P21, and then stacks the second slice layer P23 shown in Figure 14 on top of the second slice layer P22. Figure 14 is a top view showing an example of the appearance of the uppermost second slice layer P23 among the three second slice layers stacked as the second portion P2. In the example shown in Figure 14, the outline OL6 of the second slice layer P23 is formed by the extrusion of the second material by the three-dimensional molding device 1 along the build path PH11, which goes from the starting point S11 to the ending point G11, as shown in Figure 14. In this example, the infill IF6 of the second slice layer P23 is formed by the extrusion of the second material by the three-dimensional molding device 1 along the build path PH12, which goes from the starting point S12 to the ending point G12, as shown in Figure 14. In Figure 14, the build path PH11 and the build path PH12 are indicated by dotted arrows. Furthermore, in Figure 14, the hatched areas indicate the areas where the second material was extruded. In other words, in this example, the infill rate of infill IF6 is 100%. This is because the second slice layer P23 is a slice layer L that constitutes part of the surface of the three-dimensional object ML1, and is the first solid layer. Thus, in this example, the three-dimensional printing apparatus 1 gradually increases the infill rate of the second slice layer as it moves from the printing of the lower second slice layer to the printing of the upper second slice layer during the printing of the second part P2.

[0089] Furthermore, in the example shown in Figure 14, the longitudinal direction of infill IF6 is parallel to the longitudinal direction of infill IF5 of the second slice layer P22, but it may also be in a direction that intersects with the longitudinal direction in which infill IF5 extends. The longitudinal direction of infill IF6 is the direction of the longer of the two directions in which the build path PH12 extends. When these two longitudinal directions intersect, the three-dimensional printing apparatus 1 can improve the interlayer adhesion between the second slice layer P22 and the second slice layer P23.

[0090] Furthermore, in the example shown in Figure 14, the device control unit 661 forms the outline OL6 such that, when viewed from the stacking direction of the first part P1 and the second part P2, the outline OL2 of the first boundary layer B1 and the outline OL6 of the second slice layer P23 overlap. As a result, the three-dimensional molding apparatus 1 can suppress the reduction in the dimensional accuracy of the three-dimensional molded object ML1 due to the difference in the size of the outline of the first boundary layer B1 and the size of the outline of the second boundary layer B2.

[0091] If the device control unit 661 determines that the molding of the second part P2, which was started in step S160, has been completed (step S170-YES), it terminates the process shown in the flowchart in Figure 4.

[0092] As described above, when the three-dimensional molding apparatus 1 stacks a second part P2 formed of a second material onto a first part P1 formed of a first material, it stacks a first boundary layer B1 formed of the first material on top of the first part P1, stacks a second boundary layer B2 formed of the second material on top of the first boundary layer B1, and stacks the second part P2 on top of the second boundary layer B2. This allows the three-dimensional molding apparatus 1 to suppress delamination between slice layers with different thermal shrinkage rates.

[0093] In the example described above, the case where the thermal shrinkage rate of the second material is greater than that of the first material was explained. However, the thermal shrinkage rate of the second material may be smaller than that of the first material. In this case, the three-dimensional molding apparatus 1 can suppress delamination at the boundary between the first part P1 and the second part P2 by forming the first slice layer and the first boundary layer B1 described above with the second material, and forming the second boundary layer B2 and the second slice layer with the first material.

[0094] Furthermore, the device control unit 661 may, in step S110 shown in Figure 4, identify one or more boundaries between the first slice layer and the second slice layer based on the read-out three-dimensional printing data, and automatically insert the two boundary layers, the first boundary layer and the second boundary layer, into each of the identified boundaries. In this case, the three-dimensional printing apparatus 1 can suppress delamination between slice layers with different thermal shrinkage rates, even if data for the first and second boundary layers are not included in the three-dimensional printing data.

[0095] <Modification 1 of the embodiment> The following describes Modification 1 of the Embodiment. In Modification 1 of the Embodiment, as an example, we will describe the case in which the thermal shrinkage rate of the second material is greater than that of the first material. However, in Modification 1 of the Embodiment, the first slice layer and the first boundary layer are formed from the second material. Also in Modification 1 of the Embodiment, the second slice layer and the second boundary layer are formed from the first material. Furthermore, in Modification 1 of the Embodiment, the three-dimensional molding apparatus 1 fabricates a three-dimensional object ML2 as shown in Figure 15 instead of the three-dimensional object ML1.

[0096] Figure 15 shows an example of the appearance of the three-dimensional object ML2. The three-dimensional object ML2 is a roughly rectangular three-dimensional object in which a second part P4, also formed in a rectangular shape by a second slice layer of the first material, is stacked on a first part P3, also formed in a rectangular shape by a first slice layer of the second material. The three-dimensional object ML2 is a part similar to the three-dimensional object ML1. However, the three-dimensional object ML2 is fabricated in the reverse order of fabrication compared to the three-dimensional object ML1. That is, the first part P3 of the three-dimensional object ML2 corresponds to the second part P2 of the three-dimensional object ML1. Therefore, the first part P3 has the same configuration as the second part P2, except that the first slice layers corresponding to the second slice layers P21 to P23 are stacked from bottom to top in the order of the first slice layer corresponding to the second slice layer P23, the first slice layer corresponding to the second slice layer P22, and the first slice layer corresponding to the second slice layer P21, as the first slice layer of the second material. Furthermore, the second part P4 is the part corresponding to the first part P1 of the three-dimensional object ML1. Therefore, the second part P4 has the same configuration as the first part P1, except that it is formed by the second slice layer of the first material. When the three-dimensional molding apparatus 1 attempts to fabricate a three-dimensional object ML2, which is formed by laminating a second part P4 made of the first material onto a first part P3 made of the second material, it laminates a first boundary layer B3 on top of the first part P3, a second boundary layer B4 on top of the first boundary layer B3, and a second part P4 on top of the second boundary layer B4, as shown in Figure 15. Here, the first boundary layer B3 is a boundary layer having the same configuration as the first boundary layer B1, except that it is made of the second material. On the other hand, the second boundary layer B4 is a boundary layer having the same configuration as the second boundary layer B2, except that it is made of the first material. As a result, the three-dimensional molding apparatus 1 can suppress the occurrence of delamination at the boundary between the first part P3 and the second part P4, which are made of materials with different thermal shrinkage rates.In other words, even when the thermal shrinkage rate of the second material is greater than that of the first material, and the first part P3 is formed from the second material and the second part P4 is formed from the first material, the three-dimensional molding apparatus 1 can suppress the occurrence of delamination at the boundary between the first part P3 and the second part P4.

[0097] The process by which the control device 60 performs the fabrication control for fabricating the three-dimensional object ML2 is the same as the process shown in the flowchart in Figure 4. Therefore, the device control unit 661 fabricates the first part P3 in steps S120 to S130 shown in Figure 4. However, in steps S120 to S130, the device control unit 661 uses the same method and second material as the method used to form the second part P2 to stack three first slice layers on the fabrication surface 21 in the order of a first slice layer corresponding to the second slice layer P23, a first slice layer corresponding to the second slice layer P22, and a first slice layer corresponding to the second slice layer P21. Furthermore, in step S140 shown in Figure 4, the device control unit 661 fabricates the first boundary layer B3 using the same method and second material as the method used to form the first boundary layer B1. Furthermore, in step S150 shown in Figure 4, the device control unit 661 fabricates the second boundary layer B4 using the same method as the method for forming the second boundary layer B2 and the first material. Also, in steps S160 to S170 shown in Figure 4, the device control unit 661 fabricates the second part P4 using the same method as the method for forming the first part P1 and the first material. Through this process, the three-dimensional molding apparatus 1 can fabricate a three-dimensional object ML2 made of materials with different thermal shrinkage rates.

[0098] In the first modified embodiment, the case where the thermal shrinkage rate of the second material is greater than that of the first material was described. However, the thermal shrinkage rate of the second material may be smaller than that of the first material. In this case, the three-dimensional molding apparatus 1 can suppress delamination at the boundary between the first part P3 and the second part P4 by forming the first slice layer and the first boundary layer B3 described above with the first material, and forming the second boundary layer B4 and the second slice layer with the second material.

[0099] <Modified Example 2 of the Embodiment> The following describes a second modification of the embodiment. In this second modification, as an example, we will describe the case where the thermal shrinkage rate of the second material is greater than that of the first material. In this second modification, the three-dimensional molding apparatus 1 fabricates a three-dimensional object ML3 as shown in Figure 16, instead of the first three-dimensional object ML3.

[0100] Figure 16 shows an example of the appearance of the three-dimensional object ML3. The three-dimensional object ML3 is a three-dimensional object in which the three-dimensional object ML1 is stacked on top of the three-dimensional object ML2. In other words, the three-dimensional object ML3 is a three-dimensional object in which both the top and bottom surfaces are formed by slice layers L of the second material. However, in the three-dimensional object ML3, the second part P4 formed of the first material and the first part P1 formed of the first material are shared as a single object. When the three-dimensional molding apparatus 1 attempts to fabricate a three-dimensional object ML3 in which the second part P4 is stacked on the first part P3 and the second part P2 is stacked on the second part P4, as shown in Figure 16, the first boundary layer B3 of the second material is stacked on the first part P3 of the second material, the second boundary layer B4 of the first material is stacked on the first boundary layer B3 of the second material, the second part P4 of the first material is stacked on the second boundary layer B4 of the first material, the first boundary layer B1 of the first material is stacked on the second boundary layer B1 of the first material, the second boundary layer B2 of the second material is stacked on the second boundary layer B2 of the second material. As a result, the three-dimensional molding apparatus 1 can suppress delamination at the boundaries between the first part P3 and the second part P4, which are formed from materials with different thermal shrinkage rates, and at the boundaries between the second part P4 and the second part P2, which are formed from materials with different thermal shrinkage rates. Consequently, the three-dimensional molding apparatus 1 can, for example, fabricate a three-dimensional object ML3 in which both the upper and lower surfaces are formed from POM, and the space between the upper and lower surfaces is formed from ABS.

[0101] The process by which the control device 60 controls the fabrication of the three-dimensional object ML3 is an application of the flowchart shown in Figure 4. For example, the device control unit 661 fabricates the first part P3 using the same method and second material as the method for forming the first part P3 in modified embodiment 2, through the process of steps S120 to S130 shown in Figure 4. Next, the device control unit 661 fabricates the first boundary layer B3 using the same method and second material as the method for forming the first boundary layer B3 in modified embodiment 2, through the process of step S140 shown in Figure 4. Next, the device control unit 661 fabricates the second boundary layer B4 using the same method and first material as the method for forming the second boundary layer B4 in modified embodiment 2, through the process of step S150 shown in Figure 4. Next, the device control unit 661 fabricates the second part P4 using the same method and the first material as the method for forming the second part P4 in modified embodiment 2, through the processes of steps S160 to S170 shown in Figure 4. Next, the device control unit 661 fabricates the first boundary layer B1 using the same method and the first material as the method for forming the first boundary layer B1 in the embodiment, through the process of step S140 shown in Figure 4. Next, the device control unit 661 fabricates the second boundary layer B2 using the same method and the second material as the method for forming the second boundary layer B2 in the embodiment, through the process of step S150 shown in Figure 4. Then, the device control unit 661 fabricates the second part P2 using the same method and the second material as the method for forming the second part P2 in modified embodiment 2, through the processes of steps S160 to S170 shown in Figure 4. Through the above processing, the three-dimensional molding apparatus 1 can suppress the occurrence of delamination between slice layers L with different thermal shrinkage rates, even when molding a three-dimensional object ML3 made of materials with different thermal shrinkage rates.

[0102] In the modified embodiment 2, the case where the thermal shrinkage rate of the second material is greater than that of the first material was described. However, the thermal shrinkage rate of the second material may be smaller than that of the first material.

[0103] <Modification 3 of the embodiment> The following describes a third modification of the embodiment. In this third modification, as an example, we will describe the case where the thermal shrinkage rate of the second material is greater than that of the first material. In this third modification, the three-dimensional molding apparatus 1 may be configured to fabricate a three-dimensional object ML4 as shown in Figure 17, instead of the three-dimensional object ML3.

[0104] Figure 17 shows an example of the appearance of the three-dimensional object ML4. The three-dimensional object ML4 is a three-dimensional object in which three-dimensional object ML2 is stacked on top of three-dimensional object ML1. In other words, the three-dimensional object ML4 is a three-dimensional object in which both the top and bottom surfaces are formed by slice layers L of the first material. However, in the three-dimensional object ML4, the second part P2 formed by the second material and the first part P3 formed by the second material are shared as a single object. When the three-dimensional molding apparatus 1 attempts to fabricate a three-dimensional object ML4, which is formed by stacking a second part P2 on a first part P1 and stacking a second part P4 on the second part P2, it stacks the first boundary layer B1 of the first material on top of the first part P1 of the first material, stacks the second boundary layer B2 of the second material on top of the first boundary layer B1 of the first material, stacks the second part P2 of the second material on top of the second boundary layer B2 of the second material, stacks the first boundary layer B3 of the first material on top of the first boundary layer B3 of the first material, stacks the second boundary layer B4 of the second material on top of the second boundary layer B4 of the second material. As a result, the 3D printing apparatus 1 can suppress delamination at the boundary between the first part P1 and the second part P2, which are formed from materials with different thermal shrinkage rates, and at the boundary between the second part P2 and the second part P4, which are formed from materials with different thermal shrinkage rates. Consequently, the 3D printing apparatus 1 can, for example, print a 3D object ML4 in which both the upper and lower surfaces are formed from ABS and the space between the upper and lower surfaces is formed from POM.

[0105] In the third modified embodiment, the case where the thermal shrinkage rate of the second material is greater than that of the first material was described. However, the thermal shrinkage rate of the second material may be smaller than that of the first material.

[0106] <Modification 4 of the embodiment> The following describes a fourth modification of the embodiment. In this fourth modification, as an example, we will describe the case where the thermal shrinkage rate of the second material is greater than that of the first material. In this fourth modification, the three-dimensional molding apparatus 1 may be configured to fabricate a three-dimensional object ML5 as shown in Figure 18, instead of the three-dimensional object ML4.

[0107] Figure 18 shows an example of the appearance of the three-dimensional object ML5. As shown in Figure 18, the three-dimensional object ML5 is a three-dimensional object in which three-dimensional objects ML3 and ML4 are alternately stacked. The three-dimensional printing apparatus 1 can print the three-dimensional object ML5 by repeatedly performing a combination of the process of printing the three-dimensional object ML3 in the modified example 2 of the embodiment and the process of printing the three-dimensional object ML4 in the modified example 3 of the embodiment. In other words, the three-dimensional printing apparatus 1 can print the three-dimensional object ML5 by repeatedly stacking objects formed from the first material and objects formed from the second material alternately through the repetition of these combinations of processes. As a result, the three-dimensional printing apparatus 1 can simulate the creation of three-dimensional objects having desired Young's modulus, desired bending stiffness, etc., which would be impossible to achieve with a single material. Furthermore, this means that it is also possible to create three-dimensional objects that have strong bending stiffness in one direction and weak bending stiffness in other directions. Furthermore, this means that it is possible to create three-dimensional objects in which the Young's modulus differs between parts. These effects are achieved because the three-dimensional printing apparatus 1 can suppress delamination between slice layers with different thermal shrinkage rates. For example, the three-dimensional printing apparatus 1 can create three-dimensional objects in which objects made of POM and objects made of ABS are alternately layered. The Young's modulus of such a three-dimensional object will differ from that of a three-dimensional object made solely of ABS and from that of a three-dimensional object made solely of POM.

[0108] Furthermore, the elements described above can be combined in any way you like.

[0109] Furthermore, the shapes of the three-dimensional objects ML1 to ML5 described above may be any other shape instead of a roughly rectangular parallelepiped shape.

[0110] <Note> [1] A three-dimensional molding method for molding a three-dimensional object using a first material containing a first resin and a second material containing a second resin having a different thermal shrinkage rate than the first resin, wherein when a second slice layer formed by the other of the first and second materials is laminated onto a first slice layer formed by one of the first and second materials, a first boundary layer formed by the one is laminated on the first slice layer, a second boundary layer formed by the other is laminated on the first boundary layer, and a second slice layer is laminated on the second boundary layer, wherein the first boundary layer is a layer in which a plurality of voids are formed inside the contour of the first boundary layer when viewed from the lamination direction of the first and second slice layers. [2] When the first boundary layer is viewed from the stacking direction of the first slice layer and the second slice layer, the plurality of voids corresponding to the filling rate of the infill within the outline of the first boundary layer are formed inside the contour of the first boundary layer, the three-dimensional fabrication method according to [1]. [3] The three-dimensional molding method according to [2], wherein the filling rate of the infill is in the range of 20% to 90%. [4] A three-dimensional fabrication method according to any one of [1] to [3], wherein a portion of the second boundary layer is impregnated into the plurality of voids formed in the first boundary layer by stacking the second boundary layer on the first boundary layer. [5] The three-dimensional fabrication method according to any one of [1] to [4], wherein the amount supplied per unit area of ​​the other when a plurality of the second slice layers are stacked on the second boundary layer to form the second boundary layer is greater than the amount supplied per unit area of ​​the other when forming the second slice layer. [6] The three-dimensional fabrication method according to any one of [1] to [5], wherein the infill filling rate within the outline of each of the multiple second slice layers stacked on the second boundary layer is set to the lowest infill filling rate within the outline of the lowest second slice layer. [7] The three-dimensional molding method according to any one of [1] to [6], wherein the thermal shrinkage rate of the second resin is greater than the thermal shrinkage rate of the first resin. [8] The three-dimensional fabrication method according to [7], wherein the temperature of the first boundary layer when forming the first boundary layer is higher than the temperature of the first slice layer when forming the first slice layer. [9] When the first boundary layer is viewed from the stacking direction of the first slice layer and the second slice layer, the contour of the second boundary layer is contained within the contour of the first boundary layer, the three-dimensional fabrication method according to any one of [1] to [8].

[10] The three-dimensional fabrication method according to [9], wherein when forming the second boundary layer, the outline of the second boundary layer is formed and then the infill of the second boundary layer is formed.

[11] The three-dimensional fabrication method according to

[10] , wherein the temperature of the first boundary layer when forming the outline of the second boundary layer is higher than the temperature of the first boundary layer when forming the infill of the second boundary layer.

[12] The three-dimensional fabrication method according to [9], wherein when the first boundary layer is viewed from the stacking direction of the first slice layer and the second slice layer, at least a portion of the outline of the first boundary layer overlaps with at least a portion of the outline of the second slice layer.

[13] The three-dimensional fabrication method according to [9], wherein the thickness of the second boundary layer is thinner than the thickness of the second slice.

[14] A three-dimensional molding apparatus for molding a three-dimensional object using a first material comprising a first resin and a second material comprising a second resin having a different thermal shrinkage rate than that of the first resin, wherein the three-dimensional molding apparatus comprises a stage, an extrusion unit for extruding the first material and the second material respectively, a moving unit for moving the extrusion unit and the stage relative to each other, and a control unit for controlling the extrusion unit and the moving unit, wherein the control unit, when laminating a second slice layer formed of the other of the first material and the second material onto a first slice layer formed of one of the first material and the second material, laminates a first boundary layer formed of the one on the first slice layer, laminates a second boundary layer formed of the other on the first boundary layer, and laminates a second slice layer on the second boundary layer, wherein the first boundary layer is a layer on which a plurality of voids are formed inside the contour of the first boundary layer when viewed from the lamination direction of the first slice layer and the second slice layer.

[15] When the first boundary layer is viewed from the stacking direction of the first slice layer and the second slice layer, the plurality of voids corresponding to the filling rate of the infill within the outline of the first boundary layer are formed inside the contour of the first boundary layer, as described in

[14] .

[16] The three-dimensional molding apparatus according to

[15] , wherein the filling rate of the infill is in the range of 20% to 90%.

[17] A three-dimensional molding apparatus according to any one of

[14] to

[16] , wherein a portion of the second boundary layer is impregnated into the plurality of voids formed in the first boundary layer by laminating the second boundary layer on the first boundary layer.

[18] The three-dimensional molding apparatus according to any one of

[14] to

[17] , wherein the thermal shrinkage rate of the second resin is greater than that of the first resin, and the amount supplied per unit area of ​​the other when forming the second boundary layer is greater than the amount supplied per unit area of ​​the other when forming the second slice layer.

[19] The three-dimensional molding apparatus according to any one of

[14] to

[18] , wherein the control unit, when forming the second boundary layer, slows down the relative moving speed between the discharge unit and the stage using the moving unit while maintaining the supply speed by the other discharge unit.

[20] The extrusion unit extrudes the first material and the second material from a common nozzle, as described in any one of

[14] to

[19] .

[21] A control device for controlling a three-dimensional molding apparatus that molds a three-dimensional object using a first material containing a first resin and a second material containing a second resin having a different thermal shrinkage rate than the first resin, wherein the three-dimensional molding apparatus comprises a stage, an ejection unit for ejecting the first material and the second material respectively, and a moving unit for moving the ejection unit and the stage relative to each other, and the control device comprises a control unit for controlling the ejection unit and the moving unit, and the control unit is formed from one of the first material and the second material A control device in which, when a second slice layer formed of the other of the first material and the second material is laminated onto a first slice layer, a first boundary layer formed of the one is laminated on the first slice layer, a second boundary layer formed of the other is laminated on the first boundary layer, and the second slice layer is laminated on the second boundary layer, wherein the first boundary layer is a layer in which a plurality of voids are formed inside the contour of the first boundary layer when viewed from the lamination direction of the first slice layer and the second slice layer.

[22] A three-dimensional fabrication method for fabricating a three-dimensional object comprising a first portion formed from a first material containing a first resin and having a first Young's modulus, and a second portion formed from a second material containing a second resin having a different thermal shrinkage rate than the first resin and having a second Young's modulus different from the first Young's modulus.

[0111] Although embodiments of this invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may be modified, substituted, deleted, etc., as long as it does not depart from the spirit of this invention.

[0112] Furthermore, a program to realize the function of any component in the apparatus described above may be recorded on a computer-readable recording medium, and that program may be loaded into a computer system and executed. Here, the apparatus is, for example, a three-dimensional molding apparatus 1, a control device 60, a data generation apparatus 70, etc. Here, "computer system" includes hardware such as an OS (Operating System) and peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, CD (Compact Disk)-ROMs, and storage devices such as hard disks built into a computer system. Moreover, "computer-readable recording medium" also includes volatile memory inside a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which retains the program for a certain period of time.

[0113] Furthermore, the above program may be transmitted from a computer system that stores the program in a memory device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" used to transmit the program refers to a medium that has the function of transmitting information, such as a network like the Internet or a communication line like a telephone line. Furthermore, the above program may be intended to implement some of the functions described above. In addition, the above program may be one that can implement the functions described above in combination with a program already recorded in the computer system, a so-called differential file or differential program. [Explanation of symbols]

[0114] 1...3D modeling device, 10...Ejection unit, 20...Stage, 21...Modeling surface, 30...Movement unit, 31...First movement mechanism unit, 32...Second movement mechanism unit, 40...Heating unit, 50...Temperature detection unit, 60...Control device, 61...Processor, 62...Storage unit, 63...Input reception unit, 64...Communication unit, 65...Display unit, 66...Control unit, 70...Data generation device, 661...Device control unit, Nz...Nozzle, TC...3D coordinate system, X...Modeling material

Claims

1. A three-dimensional molding method for forming a three-dimensional object using a first material containing a first resin and a second material containing a second resin having a different thermal shrinkage rate than the first resin, When a second slice layer, formed from the other of the first and second materials, is laminated onto a first slice layer, formed from one of the first and second materials, The first boundary layer formed by the one described above is laminated on the first slice layer. The second boundary layer formed by the other means is laminated on top of the first boundary layer. The second slice layer is stacked on the second boundary layer, The first boundary layer is a layer in which, when viewed from the stacking direction of the first slice layer and the second slice layer, a plurality of voids are formed inside the contour of the first boundary layer. Three-dimensional modeling method.

2. When the first boundary layer is viewed from the stacking direction of the first slice layer and the second slice layer, the plurality of voids corresponding to the filling rate of the infill within the outline of the first boundary layer are formed inside the contour of the first boundary layer. The method for creating a three-dimensional object according to claim 1.

3. The filling rate of the infill is within the range of 20% to 90%. The method for creating a three-dimensional object according to claim 2.

4. By laminating the second boundary layer on top of the first boundary layer, a portion of the second boundary layer is impregnated into the plurality of voids formed in the first boundary layer. The method for creating a three-dimensional object according to claim 1.

5. Multiple second slice layers are stacked on top of the second boundary layer. The amount supplied per unit area of ​​the other layer when forming the second boundary layer is greater than the amount supplied per unit area of ​​the other layer when forming the second slice layer. The method for creating a three-dimensional object according to claim 1.

6. Of the infill filling rates within the outlines of each of the multiple second slice layers stacked on the second boundary layer, the infill filling rate within the outline of the lowest second slice layer is set to the lowest rate. The method for creating a three-dimensional object according to claim 1.

7. The thermal shrinkage rate of the second resin is greater than that of the first resin. The method for creating a three-dimensional object according to claim 1.

8. When forming the first boundary layer, the temperature of the first boundary layer is made higher than when forming the first slice layer. The method for creating a three-dimensional object according to claim 7.

9. When the first boundary layer is viewed from the stacking direction of the first slice layer and the second slice layer, the contour of the second boundary layer is included inside the contour of the first boundary layer. The method for creating a three-dimensional object according to claim 1.

10. A three-dimensional object is fabricated by laminating a first portion formed from a first material containing a first resin and having a first Young's modulus, and a second portion formed from a second material containing a second resin having a different thermal shrinkage rate than the first resin and having a second Young's modulus different from the first Young's modulus. Three-dimensional modeling method.

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