JP2021031685A - Method for manufacturing three-dimensional molded article, three-dimensional molding apparatus, program, recording medium, and die for resin molding - Google Patents

Abstract

To provide a method capable of controlling a nitridation degree in each portion to be molded, when a three-dimensional molded article containing a metal nitride is to be molded by laying a metal source powder into a layer and irradiating the layer with a laser beam to selectively solidify a part of the powder layer.SOLUTION: A method for manufacturing a three-dimensional molded article is provided, which includes repeatedly performing a powder layer formation step of depositing a metal powder to form a powder layer and a solidification step of irradiating a predetermined region of the powder layer with a laser beam to form a solidified portion. The solidification step performed during manufacturing the three-dimensional molded article includes a first solidification step and a second solidification step. In the second solidification step, a solidified portion having a larger nitridation degree than that of a solidified portion formed in the first solidification step is formed at a position different from that of the solidified portion formed in the first solidification step.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for manufacturing a three-dimensional model using a so-called powder lamination and melting method, and a three-dimensional modeling device used therefor. In particular, the present invention relates to a method of controlling the nitriding degree of each part of the three-dimensional modeled object when manufacturing the three-dimensional modeled object.

In recent years, so-called 3D printers have been actively developed, and various methods have been tried. For example, various methods such as a hot melt lamination modeling method, a stereolithography method using a photocurable resin, and a powder lamination fusion method are known.
In the powder additive manufacturing method (Power Bed Fusion), a step of laying raw material powders such as nylon resin, ceramics, and metal in layers and a step of irradiating a laser beam to selectively melt a part of the powder layer are repeated. This is a method of forming a three-dimensional model. In connection with this, a method of sintering an inorganic substance using a laser to form a model may be called a selective laser sintering method (SLS: Selective Laser Sintering).

In recent years, a powder laminating and melting method using a metal powder as a raw material has begun to be used as a method for producing an article that requires high mechanical strength and good thermal conductivity. In addition, some nitride sintered bodies such as metals have excellent properties even in a high temperature region, and are expected to be applied to mechanical parts and structural materials for high temperatures.
In Patent Document 1, a first powder such as a metal and a second powder such as a metal nitride are mixed to form a powder layer, and a nitride sintered body is manufactured by irradiating a laser beam in a nitrogen gas atmosphere. The method of doing so is disclosed.

Japanese Unexamined Patent Publication No. 2015-105201

In various fields where the application of metal nitride is expected, it may be desired that the nitriding degree is uniform throughout the article, but depending on the application, an article having a different nitriding degree for each part may be desired. ..
Patent Document 1 discloses a method for producing a nitride sintered body, but the composition is uniform except for production errors, and it is studied to control the nitriding degree of each part of a three-dimensional model. It has not been.

Therefore, when metal raw material powder is laid in layers and irradiated with laser light to selectively solidify a part of the powder layer to form a three-dimensional model containing metal nitride, each part to be modeled is formed. There has been a demand for a method capable of controlling the degree of nitriding of.

One aspect of the present invention is a tertiary process in which a powder layer forming step of depositing metal powder to form a powder layer and a solidifying step of irradiating a predetermined region of the powder layer with laser light to form a solidified portion are repeated. In the method of manufacturing the original model, the solidification step performed during the production of the three-dimensional model includes a first solidification step and a second solidification step, and in the second solidification step, the first solidification step is performed. A method for manufacturing a three-dimensional model, characterized in that a solidified portion having a higher degree of nitridedness than the solidified portion formed in the first solidification step is formed at a position different from the solidified portion formed in the first solidification step. is there.

Further, another aspect of the present invention includes a powder layer forming unit, a laser beam irradiation unit, an atmosphere adjusting unit, and a control unit, and the control unit drives the powder layer forming unit. A powder layer forming process for forming a powder layer of metal powder and a solidifying process for driving a laser beam irradiating portion to irradiate a predetermined region of the powder layer with laser light to form a solidifying portion are repeatedly performed. In a part of the solidification treatment, a first solidification treatment is performed, and in another part, a second solidification treatment is performed, and the second solidification treatment is performed at a position different from the solidification portion formed in the first solidification treatment. The three-dimensional modeling apparatus is characterized in that it is a process of forming a solidified portion having a higher degree of nitridedness than the solidified portion formed in the first solidifying process.

Another aspect of the present invention is for resin molding, wherein the contact angle of the first portion of the mold surface with water is smaller than the contact angle of the second portion of the mold surface with water. It is a mold of.

Further, in another aspect of the present invention, the first portion of the mold surface is formed of the first material, the second portion of the mold surface is formed of the second material, and the second material is the first material. It is a mold for resin molding characterized in that it is a material having a higher degree of nitriding than the material.

The present invention forms a three-dimensional model containing a metal nitride by laying a metal raw material powder in a layer and irradiating a laser beam to selectively solidify a part of the powder layer. Provided is a method capable of controlling the degree of nitriding for each site.

The schematic diagram for demonstrating the structure of the 3D modeling apparatus of embodiment. The flowchart for demonstrating the three-dimensional modeling method of an embodiment. (A) The figure which shows an example of the three-dimensional model | object which concerns on embodiment. (B) The figure which shows the slice data in the conventional three-dimensional modeling method. (C) The figure which shows an example of the slice data which concerns on the 3D modeling method of embodiment. (D) The figure which shows another example of the slice data which concerns on the 3D modeling method of embodiment. (A) to (d): Schematic diagram for explaining each step of the modeling procedure 1 according to the three-dimensional modeling method of the embodiment. (A) to (d): Schematic diagram for explaining each step of the modeling procedure 2 according to the three-dimensional modeling method of the embodiment. (A) to (d): Schematic diagram for explaining each step of the modeling procedure 3 according to the three-dimensional modeling method of the embodiment. (A) The figure which shows an example of the three-dimensional model | object which concerns on embodiment. (B) The figure which shows another example of the 3D model | object which concerns on embodiment. (A) Schematic cross-sectional view showing the structure of a diffractive optical element. (B) Schematic cross-sectional view showing a method of manufacturing a diffractive optical element. (A) The schematic diagram which shows the manufacturing mold of the diffractive optical element which concerns on embodiment. (B) An enlarged view showing an example of slice data for laminating and modeling a manufacturing mold according to an embodiment. (A) Schematic cross-sectional view showing the structure of a microlens array. (B) Schematic cross-sectional view showing a method of manufacturing a microlens array. (A) Schematic diagram showing an artificial bone according to an embodiment. (B) Schematic diagram for explaining a procedure for laminating and modeling artificial bones according to an embodiment.

A method for manufacturing a three-dimensional model, a three-dimensional modeling device, and a three-dimensional model, which are embodiments of the present invention, will be described with reference to the drawings. In the drawings referred to in the following description, unless otherwise specified, members having the same function shall be indicated with the same reference number.
Further, in the drawings referred to in the following description, the thickness of one layer may be drawn larger than the actual thickness, or the number of layers may be drawn smaller than the actual one. However, the technical scope of the present invention is not limited to the examples of the drawings.

The term sintering may also refer to a phenomenon in which an aggregate of solid powder is heated at a temperature lower than the melting point to solidify the powder into a dense object called a sintered body. However, in the following description, the term sintering is used in a broader sense. That is, sintering means that an aggregate of solid powders is integrated (solidified) through heating, and includes a case where the solid powder is melted by heating to a temperature higher than the melting point and then cooled to solidify.

[Three-dimensional modeling device]
First, the three-dimensional modeling apparatus according to the present embodiment will be described. FIG. 1 is a schematic diagram for explaining the configuration of a three-dimensional modeling apparatus.
The chamber 113 included in the three-dimensional modeling device 1 is an outer enclosure for shielding the atmosphere inside the three-dimensional modeling device 1 from the outside air. The chamber 113 is preferably a container that is substantially airtight.

The three-dimensional modeling apparatus 1 includes an atmosphere adjusting unit that adjusts the atmosphere in the chamber 113. That is, the exhaust pump 114 is connected to the chamber 113 via the exhaust adjustment valve 115, and the gas supply source 116 is connected to the chamber 113 via the air supply adjustment valve 117. The gas supply source 116 stores a gas having a nitrogen supply capacity (nitrogen supply capacity) such as nitrogen and ammonia, an inert gas such as argon, and a reducing gas such as hydrogen or a hydrocarbon gas (propane or the like). ing. The gas supply source 116 can supply various gases into the chamber 113 at a desired partial pressure via the air supply adjusting valve 117. The exhaust pump 114 can exhaust the inside of the chamber 113 at a desired exhaust speed via the exhaust adjustment valve 115. The atmosphere control in the chamber 113 will be described later.

The plate 102 is a support base for forming a three-dimensional model, but it does not necessarily have to be plate-shaped as long as it functions as a support base. The modeling table 101 is a table for mounting the plate 102, and includes a pin 103 as a position reference. The plate 102 is positioned by fitting the pin 103 and the pin hole of the plate 102. In the present embodiment, the plate 102 is detachably fixed to the modeling table 101 by screws 104, but the positioning and fixing method to the modeling table is not limited to this example. The modeling table 101 is supported so as to be movable in the vertical direction by the vertical movement mechanism 106. When forming a three-dimensional model, the formation of the powder layer and the solidification of a predetermined portion of the powder layer are repeated to stack the solidified layers, and each time the solidified layers are laminated, the modeling table 101 is lowered by the vertical movement mechanism 106. To facilitate the formation of a powder layer and irradiation of laser light. Normally, since it is moved up and down at a height of several tens of μm, it is desirable that the height resolution is 1 μm or less.

Above the modeling table 101, a powder depositing device 107 and a moving guide 108 are arranged as a powder layer forming portion. The powder depositing device 107 is a device for depositing a metal powder as a raw material on the plate 102 as a powder layer 119, and is supported by a moving guide 108 so as to be able to move in the horizontal direction. Specifically, it may be laid using a squeegee, a roller may be used, or a squeegee and a roller may be used together. Since the roller can compress the powder in the vertical downward direction, the density of the modeled object can be increased, but if the modeled object immediately after the laser irradiation has irregularities or the like, it becomes difficult to compress the powder. Since the squeegee spreads the powder while applying force in the plane direction, the effect of compressing the powder itself is small. On the other hand, when the structure has irregularities, a force is applied to the structure in the shearing direction, so that it is easy to obtain a uniform film thickness. Therefore, it is effective to use a squeegee and a roller together, adjust the powder thickness with the squeegee, and then compress with the roller to increase the density of the modeled object.

The powder as a raw material may be appropriately selected from among metal materials capable of forming nitrides by infiltrating and diffusing nitrogen by heating, depending on the use of the three-dimensional model. For example, Li, Mg, Ca, Al, Ti, Si, V, Cr, Mn, Fe, Co, Cu, Ni, Y, Zr, Nb, In, Zn, Ga, Mo, W, Hf, Ta, Ce, It can be selected from simple substances such as Th, U, and Pu, or alloys containing these.

The particle size of the metal powder may be about 5 μm to 500 μm, and is basically determined by the shape accuracy required for the three-dimensional model to be produced. If you want to obtain a finer and more accurate model, you should use a powder with a small particle size, and if you want to model at a higher speed, you should use a powder with a large particle size. In general, fine powder tends to agglomerate and it is difficult to spread the powder. Therefore, it is preferable to use a metal powder having a particle size of about 100 μm. The shape of the metal powder is preferably close to a spherical shape in order to increase the packing density when laying the powder. Further, regarding the particle size distribution, it is easier to increase the filling rate of the powder layer by using a powder having a plurality of peaks or having a gentle peak, rather than using a powder having a uniform particle size.

As a method for producing the metal powder, the gas atomization method is preferable to the water atomization method. This is because the water atomizing method can produce a large amount of powder, but the shape of the powder becomes non-spherical due to quenching. Further, in the water atomization method, the water remaining in the powder may evaporate due to laser irradiation and affect the modeled object. Since the surface of ordinary metal powder is often covered with an oxide film, a pretreatment for removing it may be performed immediately before molding. For example, since the oxide film is thinned in advance, it may be exposed to a reducing atmosphere, or the surface oxide film may be removed by wet etching in an acid solution.

A laser light source 109, a scanner 110, and a condenser lens 111 are arranged above the modeling table 101, and these are laser light irradiation units for locally and selectively irradiating a predetermined region of the powder layer 119 with the laser light LB. Consists of. As the laser light source 109, for example, a laser light source such as a fiber laser, a YAG laser, a CO ₂ laser, or an excimer laser can be used, but the laser light source 109 is not limited to any light source having a heating ability capable of sintering a powder layer. The drive method may be a pulse type or a continuous irradiation method. The irradiation wavelength is preferably selected according to the absorption wavelength of the metal powder. If possible, the absorption wavelength may be 50% or more, and more preferably 80% or more. The scanner 110 is a device for controlling the irradiation position of the laser beam LB, and for example, a galvanometer mirror can be used. A solidified layer SL is formed by sintering in the portion of the powder layer 119 that has been irradiated with the laser beam LB. The control of the irradiation power when irradiating the powder layer 119 with the laser beam LB will be described later.

The control unit 112 is a computer for controlling the operation of the three-dimensional modeling apparatus 1, and internally includes a CPU, a ROM, a RAM, an I / O port, and the like. The operation program of the three-dimensional modeling apparatus 1 is stored (recorded) in the ROM. The I / O port is connected to an external device or network, and can input / output data necessary for, for example, three-dimensional modeling to / from an external computer 118. The data required for 3D modeling includes data on the shape of the 3D model to be created and the degree of nitridement of each part, information on powder materials, and the shape and degree of nitridement of each solidified layer formed by sintering. (Ie, slice data) can be included. The slice data may be created by the CPU in the control unit 112 based on the data related to the shape of the modeled object and the nitriding degree of each part, or the slice data created by an external computer is received by the control unit 112 and recorded as a recording medium. It may be stored in the RAM which is.
Although the control unit 112 is installed inside the chamber 113 in the drawing, it may be arranged outside the chamber 113 in some cases.

The control unit 112 is connected to the vertical movement mechanism 106 of the modeling table and the powder deposition device 107 so as to be able to exchange control signals, and controls these to control the operation of forming the powder layer 119.
Further, the control unit 112 is connected to the laser light source 109, the scanner 110, and the condenser lens 111 so as to be able to send and receive control signals, and controls these to control the operation of irradiating the powder layer 119 with the laser light LB. This control includes power control of the laser light emitted by the laser light source 109, control of the position where the laser light LB is irradiated, control of the scanning speed at which the laser light LB scans on the powder layer 119, and irradiation spot diameter of the laser light LB. Control is included.

Further, the control unit 112 is connected to the exhaust adjustment valve 115, the exhaust pump 114, the air supply adjustment valve 117, and the gas supply source 116 so as to be able to send and receive control signals, and controls these to adjust the atmosphere in the chamber 113. To control. This control includes total pressure control of the atmosphere in the chamber 113, partial pressure control of a gas having a nitrogen supply ability, and partial pressure control of each of an inert gas and a reducing gas. It is desirable that a gas pressure gauge (not shown) is provided in the chamber 113 and connected to the control unit 112, and the control unit 112 performs an atmosphere adjusting operation while monitoring the partial pressures of various gases.

Next, the basic operation of the three-dimensional modeling apparatus 1 will be described.
FIG. 2 is a flowchart for explaining the basic operation of the three-dimensional modeling apparatus 1.
First, in step S1, the shape data of the article to be three-dimensionally modeled and the nitriding degree data of each part of the article are prepared. Specifically, CAD data and the like related to the design of the article are loaded into the RAM of the control unit 112.

Hereinafter, a case where the article 200 schematically shown in FIG. 3A is three-dimensionally modeled will be described. It is assumed that the article 200 is a mechanical component made of a metal (for example, Ti) and includes a portion having a relatively small nitriding degree MN (−) and a portion having a relatively large nitriding degree MN (+). Here, the nitriding degree means, for example, in the case of Ti, the ratio of Y to X when the composition ratio is expressed by TixNy in the analysis result obtained when the composition is analyzed by XPS. That is, it can be said that the larger the ratio of Y to X, the larger the degree of nitriding.

Next, in step S2, each layer required for the three-dimensional modeling apparatus 1 to stack and form a solidified layer for each layer based on the shape data of the article prepared in step S1 and the nitriding degree data of each part. Create modeling data, that is, slice data.
As shown in FIG. 3B, the slice data created by the conventional powder additive manufacturing method divides the article 200 into six layers, for example, L1 to L6, and defines only the shape of each layer. It was.

On the other hand, in the present embodiment, separate slice data is created for parts having different nitriding degrees even in the same layer, and the plane shape, thickness, and nitriding degree of the parts are linked to each slice data. Be done. That is, not only the article 200 is divided by the thickness of one layer that can be modeled, but also separate slice data is created for parts having different nitriding degrees even if they are the same layer, for example, as shown in FIG. 3C. To do. The shape of the portion and the degree of nitriding are associated with each slice data.

For example, in the third layer from the bottom, there are a portion having a small nitriding degree MN (-) and a portion having a large nitriding degree MN (+), but instead of using a single slice data L3 as in the conventional case. , L3MN (−) and L3MN (+) are created as two slice data. L3MN (−) is slice data of a portion of the third layer from the bottom where the nitriding degree is small, and is data in which the shape of this portion and the nitriding degree are linked. L3MN (+) is slice data of a portion of the third layer from the bottom having a large nitriding degree, and is data in which the shape of this portion and the nitriding degree are linked. The fourth layer from the bottom is the same as the third layer from the bottom.

Further, in the present embodiment, slice data having different thicknesses for each layer can be created. In the example of FIG. 3C, the thickness of each layer was the same, but in the example of FIG. 3D, for example, the thicknesses of L5MN'(+), L6MN'(+), and L7MN'(+) are different. The slice data is created so as to be smaller than the thickness of the layer of.

After creating the slice data in which the plane shape, the thickness, and the nitriding degree are associated with each other as described above, the slice data is loaded into the RAM of the control unit 112. The slice data may be created by the control unit 112, or may be created by an external computer and loaded into the RAM of the control unit 112.

Next, in step S3, the operating conditions of each part of the apparatus are determined based on the slice data in which the shape and the nitriding degree are associated with each other created in step S2. In other words, when creating each layer of the article 200, the procedure and parameters for controlling each part of the device are determined and stored in the RAM of the control unit 112 as a control program.

In order to explain the operating conditions of each part of the device, the principle of controlling the nitriding degree of the three-dimensional model will be described first.
Qualitatively, the temperature reached by the powder when the powder layer 119 is irradiated with the laser beam LB and heated on the condition that a gas having a nitrogen supply ability is present in the atmosphere (hereinafter referred to as the heating temperature [K]). The higher the value), the greater the degree of nitriding of the solidified layer SL.
Further, when the powder layer 119 is heated by irradiating the powder layer 119 with laser light LB, the higher the partial pressure of the gas having the nitrogen supply ability existing in the atmosphere, the more the powder layer 119 is heated to a temperature higher than the temperature at which sintering occurs. , The degree of nitriding of the solidified layer SL increases.

First, the relationship between the heating temperature [K] and the degree of nitriding will be described. When the powder layer 119 of the raw material powder made of a metal is laid by the powder depositing device 107, the surface of the raw material powder is usually covered with a metal oxide film. The raw material powder goes through the atmospheric environment from the time it is manufactured until it is introduced into the powder deposition apparatus 107, but since the metal oxidation reaction is predominant over the nitride reaction, a metal oxide film is formed on the surface. It is. Once the metal oxide film is formed on the surface of the raw material powder, even if a gas having a nitrogen supply ability exists around the powder, the metal oxide film acts as a barrier and the progress of nitriding is suppressed. On the other hand, when the powder is heated to a temperature higher than the sublimation temperature of the metal oxide by irradiating the laser beam LB, the metal oxide on the surface is sublimated, which has the effect of extinguishing the barrier against nitridation. Further, when the metal powder is heated and melted, the higher the temperature of the molten metal, the larger the diffusion coefficient of nitrogen. That is, the higher the heating temperature, the easier it is for nitrogen to diffuse into the metal, increasing the amount of solid solution and promoting nitriding. As described above, the higher the heating temperature [K] (the temperature at which the powder reaches) due to the irradiation of the laser beam LB, the greater the effect of extinguishing the barrier and the effect of promoting the diffusion of nitrogen. Becomes larger.

In order to increase the heating temperature [K], the power density [W / mm ² ] per unit area in the irradiation area irradiated with the laser beam LB and / or the irradiation time [s] for continuing the irradiation in the unit area is increased. Just let me do it. On the contrary, in order to lower the heating temperature [K], the power density [W / mm ² ] per unit area in the irradiation region and / or the irradiation time [s] for continuing the irradiation in the unit area should be controlled to be small. Just do it. ^{In order to change the power density [W / mm 2} ] in the irradiation region of the powder layer 119, the power [W] of the laser beam LB and / or the area [mm ² ] of the irradiation spot may be appropriately controlled. The power [W] of the laser beam LB can be controlled by the laser light source 109, and the area [mm ² ] of the irradiation spot can be controlled by the position of the condenser lens 111 or the modeling table 101 in the vertical direction.
Further, in order to change the irradiation time [s] per unit area where the laser light LB is irradiated, the scanning speed [mm / s] of the laser light LB on the powder layer may be appropriately controlled. The scanning speed [mm / s] of the laser beam LB on the powder layer can be controlled by the scanner 110.
The scanning pitch of the laser beam LB is made smaller than the irradiation spot diameter, and a part or all of the powder layer is irradiated with the laser beam a plurality of times to substantially reduce the irradiation time [s] per unit area. It can also be configured to be longer. For example, when the power intensity in the irradiation spot is non-uniform as in the Gaussian distribution, the heating can be made more uniform by overlapping irradiation, but at that time, the smaller the scanning pitch, the higher the heating temperature [K]. ] Can be increased. In order to change the irradiation pitch, the scanner 110 may be appropriately controlled.

Further, the heating temperature [K] can be changed by changing the thickness [μm] of the powder layer within a certain range. In three-dimensional modeling, since it is necessary to sinter the entire powder layer in the thickness direction in the laser beam irradiation region, it is premised that the thickness is within the sinterable thickness range. If the thickness [μm] of the powder layer is increased within this range, the heat capacity of the powder layer can be increased. That is, if the thickness [μm] of the powder layer is increased within the sinterable range, the heating temperature [K] is the same even ^{if the power density [W / mm 2] and the irradiation time [s] per unit area are the same.} ] Can be reduced, and the degree of nitridedness of the solidified layer SL can be reduced. On the contrary, if the thickness [μm] of the powder layer is reduced, the heat capacity is reduced. Therefore, even if the power density [W / mm ² ] and the irradiation time [s] are the same, the heating temperature [K] should be increased. The degree of nitridedness of the solidified layer SL can be increased.

Next, the relationship between the partial pressure of the nitrogen-supplying gas present in the atmosphere and the degree of nitriding will be described. For example, when the powder layer 119 is irradiated with the laser beam LB and heated, if the partial pressure [Pa] of the gas having the nitrogen supply ability in the chamber 113 is substantially zero, the solidified layer formed is substantially zero. It becomes a metal layer that does not contain nitride. When a gas having a nitrogen supply ability is present in the atmosphere in the chamber 113, the higher the partial pressure [Pa] of the gas, the easier it is for nitrogen to diffuse into the molten metal, the more the solid solution amount increases, and the degree of nitriding Has the effect of increasing. The partial pressure [Pa] of the gas having a nitrogen supply ability existing in the atmosphere in the chamber 113 can be controlled by the exhaust adjustment valve 115, the exhaust pump 114, the air supply adjustment valve 117, and the gas supply source 116.

Therefore, the type of raw material powder, the thickness of the powder layer [μm], the power of the laser beam LB [W], the scanning speed of the laser beam LB on the powder layer [mm / s], the area of the irradiation spot [mm ² ], A preliminary experiment is conducted with the partial pressure [Pa] of the gas capable of supplying nitrogen as a parameter. That is, the operation of each part of the three-dimensional modeling apparatus 1 is controlled, the modeling operation is performed for the combination in which these parameters are changed, and the nitriding degree of the solidified layer is measured. In the preliminary experiment, the power of the laser beam LB is changed in the range of, for example, 10 to 1000 [W], and the area of the irradiation spot is changed, for example, in the range of 5 to 500 [μm]. The scanning speed of the laser beam LB is changed in the range of, for example, 10 to 10,000 [m / s], and the thickness of the powder layer is changed in the range of, for example, 5 to 500 [μm]. The partial pressure of the gas having a nitrogen supply property is changed for nitrogen gas and / or ammonia gas, for example, in the range of ^{1 × 10 1 to} 3 × 10 ^{5 [Pa].} When the partial pressure of nitrogen gas and / or ammonia gas is about the same as or lower than the vapor pressure of the raw material powder, the raw material powder volatilizes and contaminates the inside of the chamber 113, so that it is a mixed gas with an inert gas such as Ar. As a result, a vacuum atmosphere sufficiently higher than the vapor pressure was created. On the other hand, when the partial pressure of nitrogen gas and / or ammonia gas is higher than the atmospheric pressure, it is preferable to provide a check valve in the chamber 113 in consideration of the occurrence of problems such as dust explosion.
Then, the degree of nitriding for each combination of these parameters is associated with the operating conditions of each part of the three-dimensional modeling apparatus 1 to create a table, which is stored in advance in the control unit 112 as a nitriding condition table.

Returning to FIG. 2, in step S3, in order to form each layer of the article 200 based on the slice data associated with the plane shape, thickness, and nitriding degree created in step S2 and the nitriding condition table stored in advance. Create the operation procedure of each part of the device. Then, it is stored in the RAM of the control unit 112 as a control program for modeling the article 200.

For example, when forming a solidified layer made of a metal that is substantially non-nitrided, the partial pressure [Pa] of the nitrogen-supplying gas existing in the chamber 113 is set to substantially zero, and when necessary. The control procedure is determined so that the heating temperature is set low. That is, a specific operation procedure of the exhaust adjustment valve 115, the exhaust pump 114, the air supply adjustment valve 117, the gas supply source 116, the laser light source 109, the scanner 110, and the condenser lens 111 is defined.

Further, when forming a solidified layer made of a metal nitride having a predetermined nitriding degree, a specific operation procedure of each part of the apparatus is determined based on the nitriding condition table. In addition, there may be a plurality of combinations of parameters that can form a solidified layer having the same nitriding degree in the nitriding condition table. In that case, the parameters are such that the power consumption is small, the amount of expensive gas used is small, and the time required to change from the formation conditions of other layers formed before and after the layer is short. The combination of is selected, and the specific operation procedure of each part of the device is determined. The user may set prioritized parameters in advance.

When a control program for modeling the article 200 is created in step S3 and stored in the RAM, the control unit 112 sequentially reads and executes the program.
That is, in step S4, the vertical movement mechanism 106 and the powder depositing device 107 are driven to form one powder layer having a predetermined thickness. This step can be referred to as a powder layer forming process or a powder layer forming step.

In the following step S5, the laser beam LB is scanned under the molding conditions for forming a solidified layer having a desired degree of nitriding to form a solidified layer having a predetermined planar shape (solidification treatment). When a plurality of solidified layers having different nitriding degrees are formed from the one powder layer formed in step S4, the laser beam LB is scanned under the molding conditions for forming each solidified layer, and the plurality of solidified layers are scanned. Will be formed in sequence.

When step S5 is completed, it is determined in step S6 whether the formation of the fully solidified layer for producing the article 200 is completed, and if it is not completed (step S6: NO), the process returns to step S4 and the next powder. Form a layer. Hereinafter, steps S4 and S5 are repeatedly executed until it is determined that the step S6 is complete (step S6: YES), and the solidified layers are laminated.
At any time during the process of repeating steps S4 and S5 to produce a three-dimensional model, the first solidification step (first solidification process) of forming a solidified portion having a small nitriding degree and the solidifying portion having a large nitriding degree The second solidification step (second solidification treatment) for forming the above is performed.

[Modeling procedure 1]
Next, a first specific example of the modeling procedure when creating the article 200 shown in FIG. 3A according to the slice data shown in FIG. 3C will be described. From the bottom solidified layer corresponding to the slice data L1MN (−) to the top solidified layer corresponding to the slice data L6MN (+) are sequentially formed.

When the mounting of the plate 102 on the modeling table 101 is completed, the three-dimensional modeling device 1 operates as follows to form the article 200 which is a three-dimensional modeled object. First, the control unit 112 sends a command to the vertical movement mechanism 106 to move the modeling table 101 to an initial position for performing a modeling operation.
Next, as a preparation for forming the solidified layer having a predetermined nitriding degree, the exhaust adjusting valve 115, the exhaust pump 114, the air supply adjusting valve 117, and the gas supply source 116 are appropriately operated to control the nitrogen gas in the chamber 113. Adjust the voltage division to PN ₂ (1). In the modeling procedure 1, the control unit 112 controls each unit so that the _{partial pressure of the nitrogen gas in the chamber 113 is maintained at PN 2} (1) until the formation of the solidified layer of the uppermost layer is completed. To do.

Next, the control unit 112 sends a command to the powder depositing device 107 to execute a powder layer forming process (powder layer forming step) for depositing the raw material powder (for example, Ti powder) on the plate 102. As shown in FIG. 4A, the lowest powder layer PLY having a thickness of t1 is formed. The powder depositing device 107 deposits powder while moving on the modeling table 101 along the moving guide 108. In the modeling procedure 1, the thickness of the powder layer to be formed thereafter is set to t1.

Next, the control unit 112 sends a command to the laser light source 109, the scanner 110, and the condenser lens 111, and irradiates the laser beam LP1 along the shape of the solidified layer to be formed as shown in FIG. 4 (b). The raw material powder is sintered to form a solidified layer having a degree of nitridedness MN (−). The laser beam LP1 is a condition (power) for forming a solidified layer having a nitriding degree of MN (-) when the thickness of the Ti powder layer is t1 in an atmosphere where the partial pressure of the nitrogen gas is PN _{2 (1).} Irradiation is performed at (density, scanning speed). As a result, a solidified layer (solidified portion) is formed in a predetermined region corresponding to the slice data L1MN (−) shown in FIG. 3 (c).

Further, the steps shown in FIGS. 4 (a) and 4 (b) are repeated in the same manner to form a solidified layer (solidified portion) corresponding to the slice data L2MN (−). After that, a powder layer for forming a solidified layer (solidified portion) corresponding to the slice data L3MN (−) and the slice data L3MN (+) is formed.

FIG. 4C shows a solidified layer having a nitriding degree MN (−) corresponding to the slice data L3MN (−) and a solidifying layer having a nitriding degree MN (+) corresponding to the slice data L3MN (+). It is a figure for demonstrating how to irradiate a laser beam. The region corresponding to the slice data L3MN (−) is irradiated with the laser beam LP1 at the power density and scanning speed described above. On the other hand, in the region corresponding to the slice data L3MN (+), the nitriding degree MN (+) is obtained when the thickness of the Ti powder layer is t1 in an atmosphere _{where the partial pressure of the nitrogen gas is PN 2 (1).} ) Is irradiated with the laser beam LP2 under the conditions (power density, scanning speed) for forming the solidified layer. Comparing the irradiation conditions of the laser light LP1 and the laser light LP2, the laser light LP2 for forming the solidified layer having a high degree of nitridedness has a higher power density and / or a lower scanning speed than the laser light LP1. .. As a result, a solidified layer (solidified portion) is formed in a predetermined region corresponding to the slice data L3MN (−) and the slice data L3MN (+) shown in FIG. 3 (c).

Further, the steps described with reference to FIG. 4C are repeated in the same manner to form a solidified layer corresponding to the slice data L4MN (−) and the slice data L4MN (+). Then, a powder layer for forming a solidified layer corresponding to the slice data L5MN (+) is formed.

FIG. 4D is a diagram for explaining how to irradiate a laser beam in order to form a solidified layer having a nitriding degree MN (+) corresponding to the slice data L5MN (+). The region corresponding to the slice data L5MN (+) is irradiated with the laser beam LP2 under the conditions (power density, scanning speed) for forming the solidified layer having the nitridedness MN (+) described above.
Further, the formation of the powder layer and the irradiation step described with reference to FIG. 4D are repeated in the same manner to form a solidified layer corresponding to the slice data L6MN (+), and the article 200 is completed.

In this modeling procedure, the power density and / or scanning speed of the laser beam to be irradiated when creating a solidified layer (solidified portion) having different nitriding degrees from one powder layer laid in one powder layer forming step is determined. changed. This change is possible by controlling the output of the laser light source 109 and / or the scanning speed by the scanner 110 and / or controlling the area of the irradiation spot by the condenser lens 111, but all of them have a high control response speed. It is possible to suppress an increase in modeling time.

[Modeling procedure 2]
A second example of a modeling procedure that can be used when creating the article 200 shown in FIG. 3A will be described. In the modeling procedure 2, as in the modeling procedure 1, from the bottom solidified layer corresponding to the slice data L1MN (−) according to the slice data shown in FIG. 3C, the most corresponding to the slice data L6MN (+). The upper solidified layer is formed in sequence.
5 (a) to 5 (d) are explanatory views of each step according to the modeling procedure 2. Of these, the steps shown in FIGS. 5 (a) to 5 (c) are shown in FIG. 4 (a). -Since it is the same as the modeling procedure 1 described with reference to FIG. 4 (c), the description thereof will be omitted.

In the modeling procedure 2, the modeling procedure of the solidified layer corresponding to the slice data L5MN (+) of the fifth layer from the bottom and the modeling procedure of the solidified layer corresponding to the slice data L6MN (+) of the sixth layer from the bottom are modeled. Different from step 1.
In the modeling procedure 1, the heating temperature of the powder layer was raised to form a solidified layer having a high degree of nitriding of these two layers. That is, a solidified layer having a high degree of nitridedness was formed by increasing the output of the laser light source 109 and / or reducing the scanning speed by the scanner 110 and / or reducing the area of the irradiation spot by the condenser lens 111. The modeling procedure 1 has an advantage that the control response speed is high, but on the other hand, if the output of the laser light source 109 is increased, the power consumption required for forming the solidified layer increases. Further, if the scanning speed is lowered, the time required for forming the solidified layer increases and the total power consumption increases. Further, if the area of the irradiation spot is reduced, the scanning pitch must be reduced in order to cover the irradiation region of the laser beam, the number of scannings increases, the time required for forming the solidified layer increases, and the total power consumption increases. Increase. That is, if the heating temperature of the powder layer is raised to increase the degree of nitriding as in the molding procedure 1, the power consumption increases.

On the other hand, in the modeling procedure 2, as shown in FIG. 5D, the nitrogen content in the atmosphere in the chamber 113 was not changed (the heating temperature of the powder layer was not changed) without changing the irradiation conditions of the laser beam. The pressure is _{changed to PN 2 (2), which is larger than PN 2} (1), to form a solidified layer with a large degree of nitriding. According to the modeling procedure 2, an increase in power consumption can be suppressed when a large-area solidified layer having a high degree of nitriding is formed or when the solidified layer having a high degree of nitriding is continuously laminated.

[Modeling procedure 3]
A third example of the modeling procedure that can be used when creating the article 200 shown in FIG. 3A will be described. In the modeling procedure 1, the article 200 shown in FIG. 3 (a) was created based on the slice data shown in FIG. 3 (c), but in the modeling procedure 3, the article 200 was created based on the slice data shown in FIG. 3 (d). To create the article 200. In the modeling procedure 1, two layers of slice data of L5MN (+) and L6MN (+) were used for the top of the article 200 having a high degree of nitriding. On the other hand, in the modeling procedure 3, a top having a high degree of nitriding is formed by using the slice data L5MN'(+) to the slice data L7MN'(+) of three layers having a smaller layer thickness.
That is, in the modeling procedure 3, when forming the top of the article 200 having a high degree of nitriding, the heat capacity per unit area is reduced by reducing the thickness of the powder layer, and the irradiation of laser light is performed as compared with the modeling procedure 1. The heating temperature for high nitriding is reached with the power reduced.
6 (a) to 6 (d) are explanatory views of each step according to the modeling procedure 3, but the steps shown in FIGS. 6 (a) to 6 (c) are shown in FIGS. 4 (a) to 4 (c). Since it is the same as the modeling procedure 1 described with reference to 4 (c), the description thereof will be omitted.

In the modeling procedure 3, as shown in FIG. 6D, the thickness t2 of the powder layer is made smaller than the thickness t1 of the lower layer (t1> t2), and the irradiation power density of the laser beam LP3 has a high nitriding degree. It was made smaller than the laser beam LP2 that formed the lower layer. Even under such laser light irradiation conditions, the powder layer having a small thickness had a small heat capacity, so that it reached a sufficient heating temperature, and it was possible to form a solidified layer having a high nitriding degree MN (+).
In the PBF method (powder layering and melting method), the laser is absorbed by the powder near the surface, which causes a thermal gradient in the depth direction, and as a result, there is a possibility that a nitrogen concentration distribution will occur in a single layer. There is. On the other hand, if the film thickness per layer is reduced and laser irradiation is performed as in the molding procedure 3, the thermal gradient can be reduced and the diffusion time of nitrogen can be shortened. Can be produced.

[Three-dimensional model]
Although the three-dimensional modeling method of the embodiment has been described by taking the article 200 shown in FIG. 3A as an example, the three-dimensional modeled object that can be modeled by the present invention is not limited to this. It does not have to be an article composed of only two types of parts, such as the article 200, a portion having a nitriding degree MN (−) and a portion having a relatively large nitriding degree MN (+).
For example, as shown in FIG. 7A, not only the nitriding degree MN (−) and nitriding degree MN (+) parts but also the nitriding degree M (0) part (from a metal having substantially zero nitriding degree). It may be an article containing a portion having a nitriding degree of MN (++), which is an extremely large nitriding degree.
Further, for example, as shown in FIG. 7B, the article may be configured so that the degree of nitriding changes in a multi-step gradation.
Further, there is no particular limitation on the shape of the three-dimensional model as long as it can be formed by the selective laser sintering method.

In the figure used in the explanation, a boundary for distinguishing between the solidified layers may be drawn for convenience of explanation, but it is not always possible to distinguish between the solidified layers in an actual three-dimensional model. Absent. In particular, the boundaries between solidified layers having the same nitriding degree may not be distinguishable due to the fusion of the solidified layers. However, the nitriding degree of each part of the article can be measured by an analytical means such as XPS.

The shape accuracy of the nitrided portion in the present embodiment can be considered separately for the in-plane resolution when the modeling stage is viewed in a plan view and the height resolution when the solid layer is viewed in the film thickness direction. The in-plane resolution depends on the laser spot diameter. For example, when a laser having a spot diameter of 60 μm is used, the in-plane resolution of the same size is obtained, and if the laser spot diameter can be narrowed down, nitriding with higher resolution becomes possible. The height resolution is a value according to the thickness of the powder layer. The height resolution depends on the operating accuracy of the vertical movement mechanism 106, but when a commercially available micrometer is used, for example, the height can be controlled with a sub μm. As described above, it is possible to form a portion and nitriding with a shape accuracy smaller than several tens of μm in both the in-plane and the height direction.

There are several properties that can be expected by nitriding a metal. For example, hardness, strength, melting point, adhesion, biocompatibility, color, optical characteristics, etc. can be controlled by the degree of nitriding. Therefore, the present invention, in combination with the above-mentioned minute modeling resolution, can be applied to the control of local characteristics when manufacturing various articles.
The following is an example in which the present invention is carried out in the manufacture of molds used for manufacturing optical parts, the manufacture of artificial bones, the manufacture of decorative parts, and the like.

[Mold for manufacturing optical parts]
An example in which the present invention is carried out in the production of a mold for manufacturing an optical component is shown.
FIG. 8A shows a diffractive optical element 300 shown as an example of an optical component, in which a resin diffractive groove PL is integrated on the optical surface of the glass lens GL. FIG. 8B is a schematic cross-sectional view for explaining a method of manufacturing the diffractive optical element 300. The glass lens GL is set facing the mold MD1, the ultraviolet curable resin is injected into the space between the glass lens GL and the mold MD1, and then the glass lens GL is irradiated with ultraviolet rays to cure the glass lens GL. A resin diffraction groove PL is attached to the lens.
In the space for injecting the ultraviolet curable resin, a portion having a small resin thickness (hereinafter referred to as a thin portion A) as indicated by A in FIG. 8B and a portion having a large resin thickness as indicated by B are provided. There is a portion (hereinafter referred to as a thick portion B).

When a conventional metal mold, that is, a mold made of a metal material having a substantially uniform composition is used, the resin is formed in a thick portion B with a gap between the recess of the mold and the resin. There was a tendency for the phenomenon of solidification (so-called sink mark) to occur. When sink marks occur in the thick portion B, the mold shape is not accurately transferred to the resin at the portion designated as DEF in FIG. 8A, so that the corners are rounded, the shape accuracy of the diffraction grating is lowered, and the optical performance is lowered. I had done it.

When a conventional metal mold is used, the sink mark phenomenon is considered to occur through the following process. When the ultraviolet curable resin injected between the glass lens GL and the mold is cured by irradiating the ultraviolet curable resin from the glass lens GL side with ultraviolet rays, the curing is first completed in the thin portion A, and then the thin portion A to the thick portion B. Curing progresses so that the cured portion expands toward. It is said that the shrinkage of the UV-curable resin when it is cured is, for example, 5% to 20%, but if the curing timing differs depending on the site, the resin will flow toward the thin portion A where the curing precedes, resulting in the shrinkage. A gap is generated at the end of the thick portion B, and sink marks occur.

In the present embodiment, in order to suppress the occurrence of sink marks, a metallic mold MD1 in which the degree of nitriding of the mold surface in contact with the resin is different depending on the site is prepared and used. By making the nitriding degree of the metal material on the mold surface in contact with the resin different depending on the part, the adhesion between the ultraviolet curable resin and the mold surface is made different for each part.

Specifically, the nitriding degree of the metal forming the mold surface of the thick portion B is made relatively smaller than the nitriding degree of the metal forming the mold surface of the thin-walled portion A. As a result, the adhesion between the ultraviolet curable resin and the mold surface is greater in the thick portion B having a relatively small nitriding degree than in the thin portion A having a relatively large nitriding degree. In this way, by making the adhesion of the mold surface of the thick portion B relatively higher than that of the thin portion A, the shrinkage of each portion during curing is balanced and the localization of the gap is suppressed. , It is possible to suppress a decrease in shape accuracy.

The contact angle of the mold surface with water is useful as an index showing the adhesion between the mold surface and the ultraviolet curable resin. When the adhesion is high, the contact angle with water becomes small, and when the adhesion is low, the contact angle becomes large. For example, in the case of Ti, Cr, Si, and Al, the contact angle of these materials with water is as small as 5 ° or less, but in the case of nitrided TiN, CrN, SiN, and AlN, the contact angle with water is as large as 50 ° or more. Become. For example, in the case of Ti, in the analysis result obtained when the composition is analyzed by XPS, the ratio of Y to X when expressing the composition ratio by TixNy, that is, by changing the degree of nitriding, the adhesion of each part of the mold surface is achieved. The sex (contact angle with water) can be controlled. Table 1 shows the relationship between the degree of nitriding and the contact angle in the case of Ti.

表１はＴｉの例であるが、Ｔｉ以外にも金型に使用可能な材料に関して窒化度と接触角の関係のデータを、予め実験等により作成しておくことが可能である。

Table 1 shows an example of Ti, but it is possible to prepare data on the relationship between the nitriding degree and the contact angle in advance by experiments or the like for materials other than Ti that can be used for the mold.

Therefore, when the mold MD1 is created by using the three-dimensional modeling apparatus 1, the degree of nitriding of the portion surrounded by the dotted line 202 in FIG. 9A, that is, the portion constituting the mold surface of the thick portion B is determined. , Make it smaller than the nitriding degree of other parts. In other words, when the portion that transfers the shape of the thick portion of the article to the resin is the first portion of the mold surface, and the portion that transfers the shape of the thin portion of the article to the resin is the second portion of the mold surface, the first portion. The second material forming the second portion has a larger degree of nitriding than the first material forming the first portion. As a result, the contact angle of the first portion of the mold surface with water is made smaller than the contact angle of the second portion of the mold surface with water.

The mold MD1 can be created by using the three-dimensional modeling apparatus 1 by any of the modeling procedure 1 to the modeling procedure 3 described above. For example, when the mold MD1 is created by the modeling procedure 1, FIG. 3C is shown. Create slice data associated with the degree of nitriding as explained with reference to. FIG. 9B is a diagram showing slice data in which the nitriding degree is associated with the portion surrounded by the dotted line 203 in FIG. 9A. A small layer of nitriding MN (-) is exposed on the mold surface of the part where sink marks are likely to occur in the past, and a large layer of nitriding MN (+) is exposed on the mold surface of other parts. It is configured as follows.

The degree of nitriding is not limited to two stages of MN (−) and MN (+), and is increased from the thick portion B to the thin portion A as described with reference to FIG. 7 (b). It may be configured so that the degree of nitriding gradually changes in each step.
Further, after modeling by any one of the above-mentioned modeling procedure 1 to modeling procedure 3, grinding or surface polishing for correcting the shape of the mold surface may be performed as necessary. When the correction process is planned, the control unit 112 uses slice data so that a layer having a predetermined nitriding degree is always present on the surface of the mold even if the thickness is reduced due to the correction process. Design the shape of.

The mold for manufacturing the diffractive optical element has been described. Next, an example of the mold for manufacturing other optical components will be given. FIG. 10A shows a microlens array 201 in which a large number of resin microlens PLMs are arranged on a glass substrate GS. FIG. 10B is a schematic cross-sectional view for explaining a method of manufacturing the microlens array 201. The glass substrate GS is set facing the mold MD2, the ultraviolet curable resin is injected into the space between the glass substrate GS and the mold MD2, and then ultraviolet rays are irradiated from the glass substrate GS side to cure the glass substrate GS. A large number of resin microlenses PLM are attached to the.

In the space for injecting the ultraviolet curable resin, a portion having a small resin thickness (hereinafter referred to as a thin portion A) as indicated as A in FIG. 10B and a portion having a large resin thickness as indicated as B are provided. There is a portion (hereinafter referred to as a thick portion B). In the portion corresponding to the thick portion B, sink marks are likely to occur in the conventional mold, and the mold shape is not accurately transferred to the resin at the portion designated as DEF in FIG. 10 (a). The radius of curvature became large and the optical performance deteriorated.

Therefore, even in the mold MD2 for creating the microlens array 201, the nitriding degree of the metal forming the mold surface of the thick portion B is higher than the nitriding degree of the metal forming the mold surface of the thin portion A. Make it relatively small. By manufacturing and using the mold MD2 by the method described above, the microlens array 201 with high shape accuracy can be mass-produced.

It should be noted that the mold made of a metal material having a different nitriding degree depending on the portion is not limited to the mold for manufacturing an optical component. According to the present invention, in a resin molding die for manufacturing various resin products, the nitriding degree of a portion corresponding to a portion where sink marks are not desired to occur in the resin product is set to be higher than the nitriding degree of other portions. It can be made relatively small, and the shape deterioration of the resin molded product due to sink marks can be suppressed. For example, in the case of suppressing sink marks that occur in the thick portion of the resin, the nitriding degree of the mold at the portion where the thick portion shape is transferred to the resin is relative to the nitriding degree of the portion where the thin wall portion shape is transferred. Can be made smaller. On the contrary, for example, in order to omit chamfering after molding, when it is desired to mold so as to locally generate sink marks, the nitriding degree of the mold portion corresponding to the portion where sink marks are desired to be generated is set to another portion. It can also be made relatively larger than the degree of nitriding of.

[Artificial bone]
Next, an example in which the present invention is carried out in the production of artificial bone will be shown. Shown in FIG. 11 (a) is a part of the artificial bone 400. The artificial bone 400 has a joint portion 301 in contact with other bones and a strut portion 302 which is a support structure. Since the joint portion 301 is in contact with other bones, wear resistance is required, but the strut portion 302 is required to have flexibility so as not to break even when it receives an impact of an external force.

Therefore, as shown in FIG. 11B, the joint portion 301 is formed by laminating and modeling a metal material having a large nitriding degree MN (+), and the strut portion 302 is a metal material having a small nitriding degree MN (−). Is formed by laminating modeling. The wear resistance of the joint portion 301 can be improved by increasing the degree of nitriding. Furthermore, the joint portion 301 is required to have biocompatibility because its lubricity is maintained by a biological membrane such as synovium, but metal nitride is known to have high biocompatibility. However, nitrides with high wear resistance work advantageously. Since it is more durable to infiltrate the biological membrane to the inside of the bone, a slice having a shape including a portion not irradiated with laser light so that a gap (not shown) is formed inside the joint portion 301. It is good to create data. By forming the strut portion 302 with a material having a nitriding degree relatively smaller than that of the joint portion 301 (including a metal that is not nitrided), it is possible to provide flexibility so that the strut portion 302 does not break even when subjected to an impact. ..
Such artificial bone can be produced by using the three-dimensional modeling apparatus 1 by any of the above-mentioned modeling procedures 1 to 3 using, for example, Ti powder.

[Decorative parts, etc.]
An example of carrying out the present invention in the manufacture of a decorative part or a functional part to which the decorative property is imparted will be described. The metal material has a color and metallic luster peculiar to the metal, but some of them change in color tone and luster by nitriding. For example, Ti is a metal having a silvery luster, but it is known that it changes to a golden color by nitriding. Further, for example, a Cu—Ti alloy can change its color from red to purple by nitriding.

According to the present invention, as described above, it is possible to control the nitriding degree of each part with high shape accuracy to perform three-dimensional modeling, so that it is possible to change the color tone peculiar to metallic luster with a fine shape. Therefore, it is possible to improve the aesthetics and visibility of an article (or part) that is visible to humans, such as a clock face or a logo plate. That is, by any of the above-mentioned modeling procedure 1 to modeling procedure 3, it is possible to create a decorative part or a functional part to which decorativeness is imparted, which has never existed before, by using the three-dimensional modeling device 1.

[Other Embodiments]
The present invention is not limited to the embodiments and examples described above, and many modifications and combinations are possible within the technical idea of the present invention.
For example, the arrangement of layers when laminating articles is not limited to the examples shown in FIGS. 3 (c), 3 (d), 9 (b), and 11 (b). It is also possible to stack layers in orthogonal directions. The optimum stacking direction may be determined from the viewpoints of the shape of the article, power consumption, amount of expensive gas used, time required for stacking, etc., and slice data linked with the degree of nitridedness may be created in step S2 of FIG. ..

Further, the modeling procedure for changing the degree of nitriding depending on the portion is not limited to the above modeling procedures 1 to 3. When changing the nitriding degree, only one of the parameters such as the power density of the laser beam, the length of the irradiation time, the thickness of the powder layer, and the partial pressure of the gas having nitrogen supply must be selected and changed. Do not mean. Multiple parameters may be changed to achieve the desired degree of nitriding.
Further, in the above, the case where the three-dimensional modeling is performed by the powder bed melting method (powder melting and laminating method) has been described, but the technical idea of the present invention can also be applied to the three-dimensional modeling by the directed energy deposition method. In other words, when performing three-dimensional modeling with the directed energy deposition method, parameters such as the power density of the laser beam, the discharge amount of the material powder, and the partial pressure of the gas having nitrogen supply are changed, and the degree of nitridedness is adjusted depending on the modeling site. Can be changed.
For example, in a method (for example, a cladding method) in which a base material processed in advance according to the approximate shape of an article to be produced is prepared and a solidified layer is formed by irradiating a laser beam while spraying raw material powder on the surface of the base material, parameters are set. It may be changed and the degree of nitriding may be changed depending on the modeling site. As the base material, it is desirable to use a material having high adhesion to the solidified layer made of metal or metal nitride, and for example, stainless steel or chromium alloy stainless steel, for example, STAVAX ESR (registered trademark) manufactured by Woodeholm Co., Ltd. is used.

The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

1 ... Three-dimensional modeling device / 101 ... Modeling table / 102 ... Plate / 106 ... Vertical movement mechanism / 107 ... Powder deposition device / 109 ... Laser light source / 110 ... Scanner / 111 ... Condensing lens / 112 ... Control unit / 113 ... Chamber / 114 ... Exhaust pump / 115 ... Exhaust adjustment valve / 116 ... Gas supply source / 117 ... Supply Air adjustment valve / 119 ... Powder layer / L1MN (-) to L4MN (-), L3MN (+) to L6MN (+) ... Slice data / MD1, MD2 ... Mold

Claims (23)

A powder layer forming process in which metal powder is deposited to form a powder layer,
A solidification step of irradiating a predetermined region of the powder layer with a laser beam to form a solidified portion,
In the method of manufacturing a three-dimensional model by repeating
The solidification step performed during the production of the three-dimensional modeled object includes a first solidification step and a second solidification step.
In the second solidification step, a solidified portion having a higher nitriding degree than the solidified portion formed in the first solidification step is formed at a position different from the solidified portion formed in the first solidification step.
A method for manufacturing a three-dimensional model, which is characterized in that. The second solidification step irradiates the laser beam in an atmosphere containing a gas having a nitrogen supply property under a condition that the heating temperature is higher than that of the first solidification step.
The method for manufacturing a three-dimensional model according to claim 1. The power density per unit area of the laser beam irradiating the powder layer in the second solidification step is larger than the power density per unit area of the laser beam irradiating the powder layer in the first solidification step.
The method for manufacturing a three-dimensional model according to claim 1 or 2. The irradiation time per unit area of the laser beam irradiating the powder layer in the second solidification step is longer than the irradiation time per unit area of the laser light irradiating the powder layer in the first solidification step.
The method for manufacturing a three-dimensional model according to any one of claims 1 to 3. The atmosphere when irradiating the laser beam in the second solidification step has a higher partial pressure of the gas having nitrogen supply than the atmosphere when irradiating the laser beam in the first solidification step.
The method for manufacturing a three-dimensional model according to any one of claims 1 to 4, wherein the three-dimensional modeled object is manufactured. The gas having a nitrogen supply property is nitrogen gas or ammonia gas.
The method for manufacturing a three-dimensional model according to claim 2 or 5. In the first solidification step, the laser beam is irradiated in an atmosphere that does not contain a gas having a nitrogen supply property.
The method for manufacturing a three-dimensional model according to any one of claims 1 to 6, wherein the three-dimensional modeled object is manufactured. The first solidification step and the second solidification step are performed on the powder layer formed in one powder layer forming step.
The method for manufacturing a three-dimensional model according to any one of claims 1 to 7. The first solidification step is performed on the powder layer formed in one powder layer forming step, and the second solidification is performed on the powder layer formed in another one powder layer forming step. Perform the process,
The method for manufacturing a three-dimensional model according to any one of claims 1 to 7. The method for manufacturing a three-dimensional model according to any one of claims 1 to 9.
A program to be executed by a 3D modeling device. The program includes a program created based on slice data in which the planar shape, thickness, and nitriding degree of the solidified portion are linked.
The program according to claim 10. A computer-readable recording medium on which the program according to claim 10 or 11 is recorded. A powder layer forming unit, a laser beam irradiation unit, an atmosphere adjusting unit, and a control unit are provided.
The control unit
A powder layer forming process for forming a powder layer of metal powder by driving the powder layer forming portion,
The solidification process of driving the laser beam irradiation unit to irradiate a predetermined region of the powder layer with laser light to form a solidification portion is repeatedly performed.
A first solidification process is performed in a part of the solidification process, and a second solidification process is performed in another part.
The second solidification treatment is a process of forming a solidification portion having a higher nitriding degree than the solidification portion formed in the first solidification treatment at a position different from the solidification portion formed in the first solidification treatment.
A three-dimensional modeling device characterized by this. The control unit executes the powder layer forming process and the solidifying process by a program created based on slice data in which the plane shape, thickness, and nitriding degree of the solidifying unit are linked.
The three-dimensional modeling apparatus according to claim 13. The control unit
After driving the atmosphere adjusting unit to form an atmosphere containing a nitrogen-supplying gas, the second solidification process is executed.
In the second solidification treatment, the laser light irradiation unit is driven under a condition that the heating temperature is higher than that of the first solidification treatment.
The three-dimensional modeling apparatus according to claim 13 or 14. The control unit
After executing the powder layer forming process of driving the powder layer forming portion to form a powder layer having a thickness of t1, the second solidification process is executed on the powder layer having a thickness of t1.
After performing the powder layer forming process of driving the powder layer forming portion to form a powder layer having a thickness of t2 larger than that of t1, the first solidification process is performed on the powder layer having a thickness of t2. To execute,
The three-dimensional modeling apparatus according to any one of claims 13 to 15. The control unit
The power density per unit area of the laser beam irradiating the powder layer in the second solidification treatment becomes larger than the power density per unit area of the laser light irradiating the powder layer in the first solidification treatment. To control the laser beam irradiation unit,
The three-dimensional modeling apparatus according to any one of claims 13 to 16. The control unit
The irradiation time per unit area of the laser beam irradiating the powder layer in the second solidification treatment is longer than the irradiation time per unit area of the laser light irradiating the powder layer in the first solidification treatment. To control the laser light irradiation unit,
The three-dimensional modeling apparatus according to any one of claims 13 to 17, wherein the three-dimensional modeling apparatus is characterized. The control unit
The atmosphere is adjusted so that the atmosphere when irradiating the laser beam in the second solidification process is higher than the atmosphere when irradiating the laser beam in the first solidification process. Control the part,
The three-dimensional modeling apparatus according to any one of claims 13 to 18. The atmosphere adjusting unit can supply nitrogen gas and / or ammonia gas.
The three-dimensional modeling apparatus according to any one of claims 13 to 19. The contact angle of the first portion of the mold surface with water is smaller than the contact angle of the second portion of the mold surface with water.
A mold for resin molding, which is characterized by this. The first portion of the mold surface is formed of the first material, the second portion of the mold surface is formed of the second material, and the second material is a material having a higher degree of nitriding than the first material.
A mold for resin molding, which is characterized by this. The first portion of the mold surface is a portion that transfers the shape of the thick portion of the article to the resin, and the second portion of the mold surface is a portion that transfers the shape of the thin portion of the article to the resin.
The mold for resin molding according to claim 21 or 22, characterized in that.

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