JP2019147992A - Lamination molding device and production method of lamination molded article - Google Patents

Abstract

To provide a lamination molding device capable of more efficiently adjusting temperature of a solidification layer.SOLUTION: A lamination molding device comprises: a chamber for covering a molding region; a material layer formation device for forming a material layer for a plurality of split layers formed by dividing a prescribed three-dimensional molded article at a prescribed height; a first radiation device for radiating a first laser light or electron beam to a prescribed radiation region of the material layer for sintering or melting the material layer for forming a solidified layer; and a second radiation device for radiating a second laser light to the formed solidified layer and heating the solidified layer to first temperature being prescribed temperature. The solidified layer heated to the first temperature is cooled to prescribed second temperature, and when the first temperature is T1, the second temperature is T2, martensitic transformation start temperature of the solidified layer is Ms, and martensitic transformation finish temperature of the solidified layer is Mf, all relationships of formulae (1)-(3), T1≥Mf(1), T1>T2(2), T2≤Ms(3) are satisfied, in the lamination molding device.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an additive manufacturing apparatus and an additive manufacturing method.

  There are several methods for additive manufacturing of metal.For example, in sintered additive manufacturing method or melt additive manufacturing method, in a sealed chamber filled with inert gas, it is placed on a forming table movable in the vertical direction. A material layer made of a metal material is formed, and a plurality of solidified layers are laminated by repeatedly irradiating a laser beam or electron beam to a predetermined portion of the material layer to sinter or melt the material powder at the irradiated position. Then, a desired three-dimensional structure is formed. A modeling plate may be arranged on the modeling table, and the first solidified layer may be formed on the modeling plate.

  In metal layered modeling, the solidified layer formed by irradiation of the material layer with laser light or electron beam is very hot immediately after solidification, but already formed solidified layer and modeling plate, or inert gas The temperature drops rapidly due to heat dissipation to the atmosphere. At this time, the volume of the metal shrinks because the coefficient of thermal expansion is positive. However, since the amount of shrinkage is limited by the close contact with the adjacent solidified layer or modeling plate, it remains as a tensile stress.

  On the other hand, when the metal material is a martensite-based material, it is an austenite phase immediately after being formed as a solidified layer, but is transformed into a martensite phase by cooling after satisfying a predetermined temperature condition and the like. . Since the martensitic transformation is accompanied by volume expansion, compressive stress is generated.

  Under the above technical background, the present applicant intentionally advances the martensitic transformation every time one or more solidified layers are formed, thereby compressing the tensile stress due to metal shrinkage by the martensitic transformation. The invention which concerns on the manufacturing method of the laminated modeling apparatus which can suppress the deformation | transformation of a molded article, and the manufacturing method of a laminated molded article by reducing the stress by controlling the residual stress of a molded article was proposed (patent document 1). In the invention of Patent Document 1, in order to intentionally advance the martensitic transformation, the temperature of the solidified layer is adjusted every time one or more solidified layers are formed.

Japanese Patent Application No. 2017-165090

  In performing such a layered modeling method, a layered modeling apparatus that can raise the temperature of the solidified layer more efficiently is desired. This invention is made | formed in view of such a situation, and provides the additive manufacturing apparatus which can perform the temperature adjustment of a solidification layer more efficiently by irradiating a solidified layer with a laser beam. .

According to the present invention, a chamber that covers a modeling area, and a material layer forming apparatus that forms a material layer for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to the modeling area. Irradiating a predetermined irradiation region of the material layer with a first laser beam or electron beam having a first irradiation spot to sinter or melt to form a solidified layer; and the first laser beam or the A second irradiation device that irradiates the solidified layer formed by an electron beam with a second laser beam and heats the solidified layer to a first temperature, which is a predetermined temperature, and the solidified layer heated to the first temperature comprises: The first temperature is T1, the second temperature is T2, the martensitic transformation start temperature of the solidified layer is Ms, and the martensitic transformation end temperature of the solidified layer is Mf. Then, the following formula Relationship from 1) (3) are all satisfied, layered manufacturing device is provided.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)

  The additive manufacturing apparatus according to the present invention can efficiently heat the solidified layer by including such a second irradiation apparatus.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, the material layer is made of carbon steel or martensitic stainless steel.
Preferably, the irradiation spot of the second laser light is larger than the irradiation spot of the first laser light or the electron beam, and surrounds the irradiation spot of the first laser light or the electron beam.
Preferably, the second laser light preheats the material layer before being irradiated with the first laser light or the electron beam.
Preferably, a modeling table arranged in the chamber and movable in the vertical direction is further provided, the material layer is formed on the modeling table, and the modeling table is temperature adjusted to the second temperature.
Preferably, the first laser light or the electron beam and the second laser light are coaxial light.
Preferably, one of the first laser beam, the electron beam, and the second laser beam is transmitted and the other is polarized in the same optical path as the one, and the first beam converted into the coaxial light by the polarization unit. Scanning means for scanning one laser beam or the electron beam and the second laser beam.
Preferably, the relationship of the following formulas (4) and (5) is further satisfied.
T1> Ms (4)
T2 <Mf (5)

According to another aspect of the present invention, a recoating step of forming a material layer for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to a modeling region, and a predetermined of the material layer A solidification step in which a solidified layer is formed by irradiating the irradiated region with a first laser beam or an electron beam to sinter or melt, and a second laser beam is applied to the solidified layer formed by the first laser beam or the electron beam. And a heating step of heating the solidified layer heated to the first temperature to a second temperature which is a predetermined temperature, and a heating step of heating the solidified layer heated to the first temperature, When the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, and the martensite transformation end temperature of the solidified layer is Mf, the relationship of the following formulas (1) to (3) Is a laminated structure Method for manufacturing objects are provided.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)

  The manufacturing method of the layered object according to the present invention can efficiently heat the solidified layer by including such a heating step.

Hereinafter, various embodiments of the present invention will be exemplified. The following embodiments can be combined with each other.
Preferably, the material layer is made of carbon steel or martensitic stainless steel.
Preferably, the irradiation spot of the second laser light is larger than the irradiation spot of the first laser light or the electron beam, and surrounds the irradiation spot of the first laser light or the electron beam.
Preferably, the method further includes a preheating step of preheating the material layer before the second laser light is irradiated with the first laser light or the electron beam.
Preferably, a modeling table arranged in the chamber and movable in the vertical direction is further provided, the material layer is formed on the modeling table, and the modeling table is temperature adjusted to the second temperature.
Preferably, the first laser light or the electron beam and the second laser light are coaxial light.
Preferably, one of the first laser beam, the electron beam, and the second laser beam is transmitted and the other is polarized in the same optical path as the one, and the first beam converted into the coaxial light by the polarization unit. Scanning means for scanning one laser beam or the electron beam and the second laser beam.
Preferably, the relationship of the following formulas (4) and (5) is further satisfied.
T1> Ms (4)
T2 <Mf (5)

1 is a schematic configuration diagram of an additive manufacturing apparatus according to an embodiment of the present invention. The perspective view of the recoater head concerning the embodiment of the present invention. The perspective view seen from another angle of the recoater head concerning the embodiment of the present invention. The schematic block diagram of the irradiation apparatus which concerns on embodiment of this invention. Explanatory drawing which shows the irradiation area | region in each division layer concerning embodiment of this invention. Explanatory drawing which shows the scanning method of the 1st laser beam and 2nd laser beam which concern on embodiment of this invention. Explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus which concerns on embodiment of this invention. Explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus which concerns on embodiment of this invention. Explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus which concerns on embodiment of this invention. Explanatory drawing which shows the irradiation method of the 1st laser beam and 2nd laser beam in a predetermined part. Schematic of the temperature change of the uppermost material layer and upper surface layer in the predetermined part by the preferable temperature adjustment example which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various characteristic items shown in the following embodiments can be combined with each other.

  The additive manufacturing apparatus according to the embodiment of the present invention forms the material layer 8 made of the material powder, and irradiates a predetermined portion of the material layer 8 with the first laser beam L1 to sinter the material powder at the irradiation position. Alternatively, it is a layered manufacturing apparatus that stacks a plurality of solidified layers to form a desired three-dimensional shaped object by repeating melting. The solidified layer is a general term for a sintered layer and a molten layer. As shown in FIG. 1, the additive manufacturing apparatus of the present invention includes a chamber 1 and an irradiation device 13.

  The chamber 1 covers a required modeling region R and is filled with an inert gas having a predetermined concentration. The chamber 1 is provided with a material layer forming device 3 inside, and a protective window contamination preventing device 17 is provided on the upper surface. The material layer forming apparatus 3 includes a base table 4 and a recoater head 11.

  The base 4 has a modeling region R where a layered product is formed. In the modeling region R, a modeling table 5 is provided. The modeling table 5 is driven by the modeling table drive mechanism 31 and can move in the vertical direction (the direction of the arrow U in FIG. 1). When the additive manufacturing apparatus is used, the modeling plate 7 is disposed on the modeling table 5 and the material layer 8 is formed thereon. In addition, the predetermined irradiation region exists in the modeling region R and approximately matches the region surrounded by the contour shape of the desired three-dimensional structure.

  The modeling table 5 is preferably configured so that the temperature can be adjusted to a desired temperature (substantially the same temperature as a second temperature described later). A temperature controller is provided inside the modeling table 5, and the temperature controller is, for example, a conduit through which a refrigerant passes. In addition, in order to prevent the thermal displacement of the modeling table drive mechanism 31, a constant temperature part maintained at a constant temperature may be provided between the temperature controller and the modeling table drive mechanism 31.

  A powder holding wall 26 is provided around the modeling table 5. In the powder holding space surrounded by the powder holding wall 26 and the modeling table 5, unsolidified material powder is held. Although not shown in FIG. 1, a powder discharge unit capable of discharging the material powder in the powder holding space may be provided below the powder holding wall 26. In such a case, the solidified material powder is discharged from the powder discharge unit by lowering the modeling table 5 after completion of the layered modeling. The discharged material powder is guided to the shooter by the shooter guide and is accommodated in the bucket through the shooter.

  As shown in FIGS. 2 and 3, the recoater head 11 includes a material storage portion 11a, a material supply portion 11b, and a material discharge portion 11c.

  The material accommodating part 11a accommodates material powder. The material supply unit 11b is provided on the upper surface of the material storage unit 11a, and serves as a receiving port for the material powder supplied from the material supply device (not shown) to the material storage unit 11a. The material discharge part 11c is provided in the bottom face of the material storage part 11a, and discharges the material powder in the material storage part 11a. In addition, the material discharge | emission part 11c is a slit shape extended in the horizontal uniaxial direction (arrow C direction) orthogonal to the moving direction (arrow B direction) of the recoater head 11. FIG.

  Further, blades 11fb and 11rb are provided on both side surfaces of the recoater head 11, respectively. The blades 11fb and 11rb distribute the material powder. In other words, the blades 11fb and 11rb form the material layer 8 by flattening the material powder discharged from the material discharging portion 11c.

  The cutting device 50 has a machining head 57 provided with a spindle head 60. The machining head 57 moves the spindle head 60 to a desired position by a machining head drive mechanism (not shown).

  The spindle head 60 is configured so that a cutting tool such as an end mill (not shown) can be attached and rotated. The spindle head 60 is applied to the surface and unnecessary portions of the solidified layer obtained by sintering or melting the material powder. Can be cut. The cutting tools are preferably a plurality of types of cutting tools, and the cutting tools to be used can be replaced during modeling by an automatic tool changer (not shown).

  A protective window contamination prevention device 17 is provided on the upper surface of the chamber 1 so as to cover the protective window 1a. The protective window contamination prevention device 17 includes a cylindrical casing 17a and a cylindrical diffusion member 17c disposed in the casing 17a. An inert gas supply space 17d is provided between the housing 17a and the diffusion member 17c. An opening 17b is provided on the bottom surface of the housing 17a inside the diffusion member 17c. The diffusion member 17c is provided with a large number of pores 17e, and the clean inert gas supplied to the inert gas supply space 17d fills the clean chamber 17f through the pores 17e. And the clean inert gas with which the clean room 17f was filled is ejected toward the downward direction of the protective window contamination prevention apparatus 17 through the opening part 17b.

  An irradiation device 13 is provided above the chamber 1. Here, the irradiation device 13 is formed by a first irradiation device 13 a that irradiates a predetermined irradiation region of the material layer 8 with the first laser light L to sinter or melt and forms a solidified layer, and the first laser L 1. And a second irradiation device 13b that irradiates the solidified layer with the second laser beam L2 and heats the solidified layer to a predetermined temperature. Specifically, as shown in FIG. 4, the first irradiation device 13a according to the present embodiment includes a first light source 42a, a first collimator 43a, and a first focus control unit 44a. The second irradiation device 13b includes a second light source 42b and a second collimator 43b. Further, polarizing means 45 and scanning means are provided. In addition, you may provide another member as needed, for example, the 2nd irradiation apparatus 13b is the 2nd focus which adjusts the 2nd laser beam L2 output from the 2nd laser light source 42b to a desired irradiation spot diameter. A control unit may be further provided.

  The first light source 42a outputs the first laser light L1. Here, the first laser light L1 is a laser capable of sintering or melting the material layer 8, and is, for example, a CO2 laser, a fiber laser, a YAG laser, or the like.

  The first collimator 43a converts the first laser light L1 output from the first laser light source 42a into parallel light. The first focus control unit 44a collects the first laser light L1 output from the first laser light source 42a and adjusts it to a desired spot diameter. Thereafter, the first laser beam L1 reaches the polarization means 45, and the polarized first laser beam, here reflected light, travels to the biaxial galvanometer mirrors 46a and 46b.

  The second light source 42b outputs the second laser light L2. Here, the second laser light L2 is a laser capable of heating the solidified layer to a desired temperature (first temperature described later), and is, for example, a CO2 laser, a fiber laser, a YAG laser, or the like. In the present embodiment, the second laser light L2 is also used for preheating the material layer 8 before being irradiated with the first laser light L1. When the second laser beam L2 is used for preheating, other preheating means are not essential. For example, the modeling table 5 may not be provided with a heater for preheating.

  The second collimator 43b converts the second laser light L2 output from the second laser light source 42b into parallel light. Preferably, the irradiation spot of the second laser light L2 is larger than the irradiation spot of the first laser light L1, and is configured to surround the irradiation spot of the first laser light L1. The irradiation spot means the irradiation position, that is, the shape of the first laser beam L1 and the second laser beam L2 in the material layer 8 or the solidified layer. When the irradiation spots of the first laser light L1 and the second laser light L2 are substantially circular, the diameter of the irradiation spot at the irradiation position of the first laser light L1 is d1, and the diameter of the irradiation spot of the second laser light L2 is d2. Then, d2 / d1 is, for example, 10 ≦ d2 / d1 ≦ 1000. By such second laser light L2, preheating of the material layer 8 before irradiation with the first laser light L1 and heating of the solidified layer irradiated with the first laser light L1 can be suitably performed. The second laser light L2 adjusted to a desired spot diameter reaches the polarization means 45, and the transmitted light travels to the biaxial galvanometer mirrors 46a and 46b.

  The polarization unit 45 transmits one of the first laser light L1 and the second laser light L2 and polarizes the other in the same optical path as the one. The polarization means 45 is a filter such as a beam splitter. As described above, in the present embodiment, the first laser light L1 polarized by the polarizing means 45 and the second laser light L2 transmitted through the polarizing means 45 become coaxial light and travel to the biaxial galvanometer mirrors 46a and 46b. Configured to do. With this configuration, the first laser beam L1 and the second laser beam L2 can be scanned at the same position by one scanning unit.

  The scanning means is, for example, a galvano scanner, and the galvano scanner includes a pair of galvanometer mirrors 46a and 46b, each of which includes an actuator that rotates the galvanometer mirrors 46a and 46b, respectively. The biaxial galvanometer mirrors 46a and 46b scan the two-dimensionally controllable first and second laser beams L1 and L2 output from the first and second laser light sources 42a and 42b. The rotation angles of the galvanometer mirrors 46a and 46b are controlled according to the magnitude of a rotation angle control signal input from a control device (not shown). With such a feature, the first laser light L1 and the second laser light L2 that have become coaxial light are irradiated to desired positions by changing the magnitude of the rotation angle control signal input to each actuator of the galvanometer mirrors 46a and 46b. can do.

  The first laser light L1 and the second laser L2 that have passed through the galvanometer mirrors 46a and 46b are transmitted through the protective window 1a provided in the chamber 1 and irradiated onto the material layer 8 formed in the modeling region R. The protective window 1a is formed of a material that can transmit the first and second laser beams L1 and L2. For example, when the first laser beam L1 and the second laser L2 are fiber lasers or YAG lasers, the protective window 1a can be made of quartz glass.

  Here, a scanning method of the first laser light L1 and the second laser light L2 in the present embodiment will be described. In the present embodiment, as shown in FIG. 5, the irradiation region in each divided layer is divided into one or more divided regions for each predetermined width w, and the first laser beam L1 and the second laser beam L2 are divided into each divided region. A scan is performed. Specifically, as indicated by arrows in FIG. 6, the scanning in the predetermined width w direction of the first laser light L1 and the second laser light L2 in the divided regions is sequentially performed along the scanning direction s orthogonal to the predetermined width w. Done. The irradiation spot of the second laser beam L2 is larger than the irradiation spot of the first laser beam L1, and the center of each irradiation spot is substantially the same. Therefore, in each part on the irradiation region, it is more than the first laser beam L1. The second laser beam L2 is irradiated for a longer time. In addition, the scanning method of the 1st laser beam L1 and the 2nd laser beam L2 which were shown above is an example to the last, and various scanning methods are employable. Specifically, although an example of so-called raster scanning has been described above, vector scanning or a combination thereof may be used. Further, the divided areas may be set by an arbitrary method.

The additive manufacturing apparatus according to the embodiment of the present invention is characterized in that the upper surface layer is heated to the first temperature using at least the second irradiation device 13b described above, and then the upper surface layer is cooled to the second temperature. When the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, and the martensite transformation end temperature of the solidified layer is Mf, the following formulas (1) to (3) All relationships are satisfied.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
After the sintering or melting, the upper surface layer before being cooled is in a state containing an austenite phase, and at least a part is transformed into a martensite phase by cooling. Note that the upper surface layer is subjected to temperature adjustment performed in a series of order of the first temperature, the second temperature, and the first temperature after being formed, in other words, heating and cooling for martensitic transformation are performed once. This refers to a solidified layer. In the present embodiment, specifically, the upper surface layer is the uppermost solidified layer at the time of the heating process described later.

  As described above, it is possible to heat the upper surface layer to the first temperature, which is a desired temperature, by configuring the second irradiation device 13b. Further, the upper surface layer heated to the first temperature is cooled to the second temperature by radiating heat to the lower solidified layer, the modeling plate 7 and the surrounding inert gas. In particular, as in the present embodiment, when the temperature of the modeling table 5 is adjusted to substantially the same temperature as the second temperature, the upper surface layer can be cooled more efficiently.

  The additive manufacturing apparatus uses a temperature sensor (not shown) that measures the temperature of the uppermost material layer 8 or the upper surface layer, and the scanning speed of the second laser beam L2, the laser intensity, the size of the irradiation spot diameter, and the like. Feedback control may be performed. With this configuration, the temperature of the uppermost material layer 8 or the upper surface layer can be controlled more accurately. A plurality of temperature sensors may be provided. The temperature sensor is, for example, an infrared temperature sensor.

  The chamber 1 is supplied with an inert gas having a predetermined concentration and exhausts an inert gas containing fumes generated when the material layer 8 is sintered or melted. Specifically, an inert gas supply device 15 and a fume collector 19 are connected to the chamber 1 via duct boxes 21 and 23. The inert gas supply device 15 has a function of supplying an inert gas, and includes, for example, a membrane nitrogen separator that extracts nitrogen gas from ambient air. The inert gas supply device 15 supplies an inert gas from a supply port provided in the chamber 1 and fills the chamber 1 with an inert gas having a predetermined concentration. Further, the inert gas containing a large amount of fumes discharged from the discharge port of the chamber 1 is sent to the fume collector 19 and is returned to the chamber 1 after the fumes are removed. In this specification, the inert gas means a gas that does not substantially react with the material powder, and an appropriate gas is selected from nitrogen gas, argon gas, helium gas, etc. according to the type of the material powder. The

  Here, each process in the manufacturing method of the laminate-molded article which concerns on one Embodiment of this invention is demonstrated using FIGS. 7-9 and FIG. 10A-FIG. 10E. 7 to 9, some of the components shown in FIG. 1 are omitted in consideration of visibility. Further, in the following, a step of forming the material layer 8 for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to the modeling region R is irradiated with the first laser light L1. A preheating step in which the second laser beam L2 preheats the material layer 8 before being heated, and a step in which a predetermined irradiation region of the material layer 8 is irradiated with the first laser beam L1 to be sintered or melted to form a solidified layer. A step of heating the solidified layer formed by the first laser beam L1 to the first temperature by irradiating the second laser beam L2, and a step of cooling the solidified layer heated to the first temperature to the second temperature. This is called a cooling process. .

  First, the first recoating step is performed. As shown in FIG. 7, the modeling plate 7 is mounted on the modeling table 5, and the height of the modeling table 5 is adjusted to an appropriate position. In this state, the recoater head 11 in which the material powder is filled in the material container 11a is moved from the left side to the right side of the modeling region R in the direction of arrow B in FIG. The material layer 8 is formed.

  Next, a first preheating step, a solidifying step, a heating step, and a cooling step are performed. Although a preheating process, a solidification process, a heating process, and a cooling process are performed in parallel, if a certain part is noted, it will be performed in order of a preheating process, a solidification process, a heating process, and a cooling process. Here, attention should be paid to the predetermined portion P in FIGS. 10A to 10E. 10A to 10E schematically show scanning of the first laser light L1 and the second laser light L2 in the predetermined width w direction including the predetermined part P in the scanning path.

  In the state shown in FIG. 10A, the material layer 8 at the predetermined site P is not irradiated with the first laser light L1 and the second laser light L2, and represents a state before preheating. At this time, the temperature of the predetermined part P is kept at the second temperature. Here, the first preheating step is performed at the predetermined portion P. As shown in FIG. 10B, the first laser light L1 and the second laser light L2 are scanned in the scanning direction in the figure, and the predetermined laser beam P2 is irradiated to the predetermined portion P. As a result, the predetermined portion P is preheated to a temperature suitable for solidification. The second laser is scanned before the first laser beam L1 and the second laser beam L2 are scanned in the divided regions until the temperature of the material layer 8 in the vicinity of the scanning start point in each divided region is raised to a temperature suitable for solidification. It is desirable to irradiate the material layer 8 near the start point for a predetermined time with the light L2.

  Next, the first solidification step is performed at the predetermined portion P. That is, as shown in FIG. 10C, the first laser beam L <b> 1 is irradiated to a predetermined portion P in the material layer 8 to sinter or melt the laser irradiation position of the material layer 8. That is, the predetermined part P becomes a solidified layer (a part of the first solidified layer 81f as shown in FIG. 8).

  Next, the first heating step is performed at the predetermined portion P. As shown in FIG. 10D, the predetermined portion P that has become a solidified layer is heated by being irradiated with the second laser light L2. The predetermined part P reaches at least the first temperature by the heating. After the first laser beam L1 and the second laser beam L2 have finished scanning in the divided regions until the solidified layer near the end point of scanning in each divided region is sufficiently heated so that martensitic transformation occurs after cooling, It is desirable to irradiate the solidified layer near the end point for a predetermined time with the second laser beam L2. In addition, the heating time and the heating temperature in the heating process are set to appropriate values according to the metal material to be used or the metal material to be used. For example, the scanning speed of the second laser beam L2, the laser intensity, the irradiation spot It can be adjusted according to the size of the diameter.

  Next, a first cooling step is performed at the predetermined portion P. As shown in FIG. 10E, since the heating of the predetermined portion P by the second laser beam L2 is completed, the predetermined portion P is deprived of heat by the lower solidified layer, the modeling plate 7, an inert gas atmosphere, etc. Until cooled.

  Through the first steps, a first solidified layer 81f as shown in FIG. 8 is formed.

  Next, as a second recoating step, the height of the modeling table 5 is lowered by a predetermined thickness (one layer) of the material layer 8, and the recoater head 11 is moved from the right side to the left side of the modeling region R, thereby solidifying the layer. A second material layer 8 is formed on 81f.

  Next, a second preheating step, a solidifying step, a heating step, and a cooling step are performed. Each step is the same as the first step.

  Through these second steps, a second solidified layer 82f as shown in FIG. 9 is formed.

  By repeating the above steps, the third and subsequent solidified layers are formed.

  In the additive manufacturing apparatus including the cutting device 50 as in the present embodiment, every time a predetermined number of solidified layers are formed, the end surface of the solidified layer is cut by a rotary cutting tool attached to the spindle head 60. You may implement the cutting process which processes. The cutting process is performed each time the solidified layer is laminated with a predetermined thickness of 0.4 mm to 1 mm, for example. In addition, spatter generated during sintering or melting may adhere to the surface of the solidified layer and produce a protrusion. If the recoater head 11 collides with the protrusion during the recoating process, the protrusion is removed. Therefore, cutting may be performed on the upper surface of the uppermost solidified layer.

  Such a recoating process, a preheating process, a solidifying process, a heating process, and a cooling process, and preferably a cutting process are repeated to form a desired three-dimensional structure.

  By the temperature adjustment process as described above, that is, the heating process and the cooling process, it is possible to reduce the tensile stress caused by the shrinkage due to the cooling of the solidified layer and to suppress the deformation of the modeled object. That is, in the metal material in which martensitic transformation occurs, the volume expands during the martensitic transformation, and the volume shrinkage during cooling is alleviated. Here, the martensitic transformation occurs in the range below the martensitic transformation start temperature and above the martensitic transformation end temperature.

Further, this transformation amount (= expansion amount) can be controlled by the relationship between the first temperature, the second temperature, the martensite transformation end temperature, and the martensite transformation start temperature. That is, the residual stress of the shaped article can be controlled by their temperature relationship. In particular, in the additive manufacturing apparatus according to the present embodiment, an example as shown in FIG. 11 is preferable. This graph represents temperature changes of the uppermost material layer 8 and the upper surface layer at the predetermined portion P. In the example shown in FIG. 11, both the first temperature and the second temperature are not included in the temperature range where martensitic transformation occurs. That is, all the following formulas (1) to (5) are satisfied.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1> Ms (4)
T2 <Mf (5)

  In this temperature pattern, the upper limit of the first temperature and the lower limit of the second temperature are not limited as long as the temperature can be adjusted, so that temperature control becomes easy. In particular, in the additive manufacturing apparatus according to the present embodiment, the upper layer is heated using the second laser beam L2, so that a high first temperature can be realized. That is, it is also effective when the martensitic transformation start temperature (Ms) is relatively high. In addition, the cooling is started from the martensite transformation start temperature or higher and is cooled to the martensite transformation end temperature or lower, in other words, the martensite transformation is caused in the entire temperature range where the martensite transformation occurs, so that the reproducibility is high. This is a control method suitable for materials in which the amount of expansion due to martensitic transformation is equal to or less than the amount of shrinkage during modeling.

  The material powder that can be used in the method for producing a metal layered object according to an embodiment of the present invention is a metal material that causes martensitic transformation, for example, carbon steel or martensitic stainless steel powder. The shape of the material powder is, for example, a sphere with an average particle diameter of 20 μm.

  It has also been found that the martensitic transformation start temperature and martensitic transformation end temperature vary depending on the carbon content of the material. Then, the modeling method using the martensitic transformation of the present invention can be applied to various materials by adjusting the carbon content of the material.

  As a method for adjusting the carbon content of the material, for example, a plurality of materials may be mixed. Specifically, a mixed material having a desired martensite transformation start temperature or martensite transformation end temperature is produced by mixing at least one of a metal having a relatively high carbon content or carbon with a certain metal. May be.

  The additive manufacturing apparatus according to the embodiment of the present invention can also be implemented in the following manner, and can be expected to exhibit the same effect.

  1stly, although the additive manufacturing apparatus which concerns on embodiment of this invention was an additive manufacturing apparatus by a powder sintering additive manufacturing method or a powder fusion additive manufacturing method, the additive manufacturing apparatus by a sheet | seat lamination method may be sufficient. That is, it is configured so that a material layer is formed using a plate-like metal sheet instead of the material powder, and the metal sheet is melted by irradiating a predetermined portion of the material layer with the first laser beam L1. Also good.

  Secondly, in the present embodiment, the first irradiation device 13a that irradiates the first laser beam L1 is used as the irradiation device for forming the solidified layer. However, even if the first irradiation device that irradiates the electron beam is used. Good. In this case, in the description according to the above-described embodiment, the first laser light L1 may be read as an electron beam, and thus detailed description is omitted.

  Thirdly, in the additive manufacturing apparatus according to the embodiment of the present invention, the first laser light L1 polarized by the polarizing means 45 and the second laser light L2 transmitted through the polarizing means 45 become coaxial light and are biaxial galvano. The first irradiation device 13a and the second irradiation device 13b are arranged so as to proceed to the mirrors 46a and 46b. However, these are interchanged so that the first laser light L1 transmitted through the polarizing means 45 and the second laser light L2 polarized by the polarizing means 45 become coaxial light and travel to the biaxial galvanometer mirrors 46a and 46b. You may implement.

Fourth, as long as all the relationships of the following formulas (1) to (3) are satisfied,
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
The first temperature and the second temperature may not be constant during modeling. For example, the specific numerical values of the first temperature and the second temperature may change for each divided layer.

  Fifth, in the present embodiment, the preheating step, the solidification step, the heating step, and the cooling step were performed in parallel, but each step is performed in the order of the preheating step, the solidification step, the heating step, and the cooling step. For example, the preheating step, the solidifying step, the heating step, and the cooling step may not be performed in parallel. For example, every time the solidification process related to the formation of one or more solidified layers is completed, the solidification process using the second laser beam L2 may be performed. In this case, the upper surface layer is one or a plurality of solidified layers including at least the uppermost solidified layer at the time of the heating step.

  Although embodiments of the present invention and modifications thereof have been described, these are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1: Chamber 1a: Protection window 3: Material layer forming device 4: Base table 5: Modeling table 7: Modeling plate 8: Material layer 11: Recoater head 11a: Material container 11b: Material supply unit 11c: Material discharge unit 11fb : Blade 11rb: blade 13: laser irradiation device 13a: first irradiation device 13b: second irradiation device 15: inert gas supply device 17: protective window contamination prevention device 17a: housing 17b: opening 17c: diffusion member 17d: Inert gas supply space 17e: pore 17f: clean chamber 19: fume collector 21: duct box 23: duct box 26: powder holding wall 31: modeling table drive mechanism 42a: first light source 42b: second light source 43a: first 1 collimator 43b: second collimator 44a: first focus control unit 45 Polarizing means 46a: galvanomirror 46b: galvanomirror 50: Cutting device 57: the processing head 60: Spindle head 81f: solidified layer 82f: solidified layer L1: first laser beam L2: second laser beam P: a predetermined portion R: shaping region

According to the present invention, a chamber that covers a modeling area, and a material layer forming apparatus that forms a material layer for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to the modeling area. A first irradiation device that irradiates a predetermined irradiation region of the material layer with a first laser beam or an electron beam to sinter or melt to form a solidified layer, and the first irradiation unit is formed by the first laser beam or the electron beam. A second irradiation device that irradiates the solidified layer with a second laser beam and heats the solidified layer to a first temperature, which is a predetermined temperature, and the solidified layer heated to the first temperature has a predetermined temperature. When cooled to the second temperature, the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, and the martensite transformation end temperature of the solidified layer is Mf. The relationship from 1) to (3) Is satisfied Te layered manufacturing device is provided.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)

An irradiation device 13 is provided above the chamber 1. Here, the irradiation device 13 is formed by a first irradiation device 13 a that irradiates a predetermined irradiation region of the material layer 8 with the first laser light L to sinter or melt and forms a solidified layer, and the first laser L 1. A second irradiation device 13b that irradiates the solidified layer with the second laser beam L2 and heats the solidified layer to a predetermined temperature; Specifically, as shown in FIG. 4, the first irradiation device 13a according to the present embodiment includes a first light source 42a, a first collimator 43a, and a first focus control unit 44a. The second irradiation device 13b includes a second light source 42b and a second collimator 43b. Further, polarizing means 45 and scanning means are provided. In addition, you may provide another member as needed, for example, the 2nd irradiation apparatus 13b is 2nd focus control which adjusts the 2nd laser beam L2 output from the 2nd light source 42b to a desired irradiation spot diameter. A unit may be further provided.

The first collimator 43a converts the first laser light L1 output from the first light source 42a into parallel light. The first focus control unit 44a collects the first laser light L1 output from the first light source 42a and adjusts it to a desired spot diameter. Thereafter, the first laser beam L1 reaches the polarization means 45, and the polarized first laser beam, here reflected light, travels to the biaxial galvanometer mirrors 46a and 46b.

The second collimator 43b converts the second laser light L2 output from the second light source 42b into parallel light. Preferably, the irradiation spot of the second laser light L2 is larger than the irradiation spot of the first laser light L1, and is configured to surround the irradiation spot of the first laser light L1. The irradiation spot means the irradiation position, that is, the shape of the first laser beam L1 and the second laser beam L2 in the material layer 8 or the solidified layer. When the irradiation spots of the first laser light L1 and the second laser light L2 are substantially circular, the diameter of the irradiation spot at the irradiation position of the first laser light L1 is d1, and the diameter of the irradiation spot of the second laser light L2 is d2. Then, d2 / d1 is, for example, 10 ≦ d2 / d1 ≦ 1000. By such second laser light L2, preheating of the material layer 8 before irradiation with the first laser light L1 and heating of the solidified layer irradiated with the first laser light L1 can be suitably performed. The second laser light L2 adjusted to a desired spot diameter reaches the polarization means 45, and the transmitted light travels to the biaxial galvanometer mirrors 46a and 46b.

The scanning means is, for example, a galvano scanner, and each of the pair of galvanometer mirrors 46a and 46b of the galvano scanner includes an actuator that rotates the galvanometer mirrors 46a and 46b, respectively. The biaxial galvanometer mirrors 46a and 46b scan the two-dimensionally controllable first and second laser beams L1 and L2 output from the first and second light sources 42a and 42b. The rotation angles of the galvanometer mirrors 46a and 46b are controlled according to the magnitude of a rotation angle control signal input from a control device (not shown). With such a feature, the first laser light L1 and the second laser light L2 that have become coaxial light are irradiated to desired positions by changing the magnitude of the rotation angle control signal input to each actuator of the galvanometer mirrors 46a and 46b. can do.

The additive manufacturing apparatus according to the embodiment of the present invention is characterized in that the upper surface layer is heated to the first temperature using at least the second irradiation device 13b described above, and then the upper surface layer is cooled to the second temperature. When the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, and the martensite transformation end temperature of the solidified layer is Mf, the following formulas (1) to (3) All relationships are satisfied.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
After the sintering or melting, the upper surface layer before being cooled is in a state containing an austenite phase, and at least a part is transformed into a martensite phase by cooling. Note that the upper surface layer, a first temperature after being formed, the temperature adjustment performed by the sequential order of the second temperature, heating and cooling for the martensitic transformation is not performed even once in other words solidified Refers to the layer. In the present embodiment, specifically, the upper surface layer is the uppermost solidified layer at the time of the heating process described later.

Here, each process in the manufacturing method of the laminate-molded article which concerns on one Embodiment of this invention is demonstrated using FIGS. 7-9 and FIG. 10A-FIG. 10E. 7 to 9, some of the components shown in FIG. 1 are omitted in consideration of visibility. Further, in the following, a step of forming the material layer 8 for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to the modeling region R is irradiated with the first laser light L1. A preheating step in which the second laser beam L2 preheats the material layer 8 before being heated, and a step in which a predetermined irradiation region of the material layer 8 is irradiated with the first laser beam L1 to be sintered or melted to form a solidified layer. A step of heating the solidified layer formed by the first laser beam L1 to the first temperature by irradiating the second laser beam L2, and a step of cooling the solidified layer heated to the first temperature to the second temperature. This is called a cooling process .

Next, a first cooling step is performed at the predetermined portion P. As shown in FIG. 10E, since the heating of the predetermined portion P by the second laser beam L2 is completed, the predetermined portion P is deprived of heat by the modeling plate 7 or the inert gas atmosphere (as described above, the second and subsequent times) In the cooling step, heat is also taken away by the lower solidified layer) , and is cooled to the second temperature.

1: Chamber 1a: Protection window 3: Material layer forming device 4: Base table 5: Modeling table 7: Modeling plate 8: Material layer 11: Recoater head 11a: Material container 11b: Material supply unit 11c: Material discharge unit 11fb : Blade 11rb: blade 13: irradiation device 13a: first irradiation device 13b: second irradiation device 15: inert gas supply device 17: protective window contamination prevention device 17a: housing 17b: opening 17c: diffusion member 17d: non Active gas supply space 17e: Fine hole 17f: Clean chamber 19: Fume collector 21: Duct box 23: Duct box 26: Powder holding wall 31: Modeling table drive mechanism 42a: First light source 42b: Second light source 43a: First Collimator 43b: Second collimator 44a: First focus control unit 45: Polarized light Stage 46a: galvanomirror 46b: galvanomirror 50: Cutting device 57: the processing head 60: Spindle head 81f: solidified layer 82f: solidified layer L1: first laser beam L2: second laser beam P: a predetermined portion R: shaping region

Claims (16)

A chamber covering the modeling area;
A material layer forming apparatus for forming a material layer for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to the modeling region;
A first irradiation device that forms a solidified layer by irradiating a first laser beam or an electron beam having a first irradiation spot to a predetermined irradiation region of the material layer to sinter or melt;
A second irradiation device that heats the solidified layer formed by the first laser beam or the electron beam to a first temperature that is a predetermined temperature by irradiating the solidified layer with a second laser beam;
The solidified layer heated to the first temperature is cooled to a second temperature, which is a predetermined temperature,
When the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, and the martensite transformation end temperature of the solidified layer is Mf, the following formulas (1) to (3) All relationships are satisfied,
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
Additive manufacturing equipment. The material layer is made of carbon steel or martensitic stainless steel.
The additive manufacturing apparatus according to claim 1. The irradiation spot of the second laser light is larger than the irradiation spot of the first laser light or the electron beam and surrounds the irradiation spot of the first laser light or the electron beam.
The additive manufacturing apparatus according to claim 1 or 2. The second laser light preheats the material layer before being irradiated with the first laser light or the electron beam.
The additive manufacturing apparatus according to any one of claims 1 to 3. Further comprising a shaping table arranged in the chamber and movable in the vertical direction;
The material layer is formed on a modeling table,
The modeling table is temperature adjusted to the second temperature,
The additive manufacturing apparatus according to any one of claims 1 to 4. The first laser light or the electron beam and the second laser light are coaxial light,
The additive manufacturing apparatus according to any one of claims 1 to 5. Polarizing means for transmitting one of the first laser light, the electron beam, or the second laser light and polarizing the other in the same optical path as the one;
Scanning means for scanning the first laser light or the electron beam and the second laser light that have been converted into coaxial light by the polarizing means;
The additive manufacturing apparatus according to claim 6. Further satisfy the relationship of the following formulas (4) and (5):
T1> Ms (4)
T2 <Mf (5)
The additive manufacturing apparatus according to any one of claims 1 to 7. A recoating step of forming a material layer for each of a plurality of divided layers obtained by dividing a desired three-dimensional structure at a predetermined height with respect to a modeling region;
A solidification step in which a predetermined irradiation region of the material layer is irradiated with a first laser beam or an electron beam to be sintered or melted to form a solidified layer;
A heating step of irradiating the solidified layer formed by the first laser beam or the electron beam with a second laser beam to heat it to a first temperature which is a predetermined temperature;
Cooling the solidified layer heated to the first temperature to a second temperature, which is a predetermined temperature, and
When the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, and the martensite transformation end temperature of the solidified layer is Mf, the following formulas (1) to (3) All relationships are satisfied,
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
Manufacturing method of layered object. The material layer is made of carbon steel or martensitic stainless steel.
The method for producing a layered object according to claim 9. The irradiation spot of the second laser light is larger than the irradiation spot of the first laser light or the electron beam and surrounds the irradiation spot of the first laser light or the electron beam.
The manufacturing method of the laminate-molded article of Claim 9 or Claim 10. A preheating step of preheating the material layer before the second laser light is irradiated with the first laser light or the electron beam;
The method for producing a layered object according to any one of claims 9 to 11. Further comprising a shaping table arranged in the chamber and movable in the vertical direction;
The material layer is formed on a modeling table,
The modeling table is temperature adjusted to the second temperature,
The method for manufacturing a layered object according to any one of claims 9 to 12. The first laser light or the electron beam and the second laser light are coaxial light,
The method for manufacturing a layered object according to any one of claims 9 to 13. Polarizing means for transmitting one of the first laser light, the electron beam, or the second laser light and polarizing the other in the same optical path as the one;
Scanning means for scanning the first laser light or the electron beam and the second laser light that have been converted into coaxial light by the polarizing means;
The method for producing a layered object according to claim 14. Further satisfy the relationship of the following formulas (4) and (5):
T1> Ms (4)
T2 <Mf (5)
The method for manufacturing a layered object according to any one of claims 9 to 15.