JP6556296B1 - Manufacturing method of layered objects - Google Patents

Abstract

An object of the present invention is to provide an additive manufacturing apparatus and an additive manufacturing method for suppressing unintended martensitic transformation. A material layer forming apparatus that forms a material layer for a plurality of divided layers of a three-dimensional structure, and a solidified layer formed by sintering or melting the irradiated region of the material layer by irradiating a first beam. 1 irradiation device and a temperature adjusting device for adjusting the temperature of at least a part of the solidified layer to a predetermined first temperature or the second temperature, and at least a part of the solidified layer reaches the first temperature and then 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, the transformation end temperature is Mf, and the minimum temperature at which the three-dimensional structure is exposed after modeling is Tm, the following formula T1 ≧ Mf (1) T1> T2 (2) T2 ≦ Ms (3) T1 ≧ Ms (4) T2> Mf (5) T2 ≦ Tm (6) or the following formula: T1 ≧ Mf (1) T1> T2 (2) T2 ≦ Ms (3) T1 ≦ Ms (7) T2> Mf (5) T2 ≦ Tm 6) All additive manufacturing apparatus filled. [Selection] Figure 13

Description

This invention relates to a method of manufacturing a product layer shaped object.

  In the additive manufacturing of metal, the present applicant intentionally advances the martensite transformation every time one or more solidified layers are formed, so that the tensile stress due to the shrinkage of the metal is expressed by the compressive stress due to the martensitic transformation. The invention which concerns on the manufacturing method of the additive manufacturing apparatus and additive manufacturing model which can suppress the deformation | transformation of an object by reducing and controlling the residual stress of an object was proposed. Specifically, when the first temperature as a predetermined temperature is T1, the second temperature as a predetermined 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. , T1 ≧ Mf, T1> T2 and T2 ≦ Ms are satisfied at a temperature condition, and each time one or more solidified layers are formed, the solidified layer heated to the first temperature is set to the second temperature. To cool to advance the transformation including martensitic transformation.

Japanese Patent No. 6295001

  In the case where the second temperature is included in the temperature range in which martensitic transformation occurs, that is, the temperature range below the martensitic transformation start temperature Ms and above the martensitic transformation end temperature Mf, the temperature of the shaped article is the second after the shaping is completed. When the temperature becomes lower than the temperature, the martensitic transformation further proceeds, and unintended expansion may occur.

The present invention has been made in view of such circumstances, on unintended martensitic transformation after molding completion is prevented from traveling to control the residual stress of the molded article, the manufacturing method of the product layer the shaped object The main purpose is to provide

Further, according to the present invention, the step of setting the second temperature, which is a predetermined temperature, to a temperature that is equal to or lower than the lowest temperature at which the three-dimensional structure that changes according to the application is exposed after the modeling is desired, and desired for the modeling region A material layer forming step of forming a material layer for each of a plurality of divided layers obtained by dividing the three-dimensional structure at a predetermined height, and irradiating a first irradiation to a predetermined irradiation region of the material layer in the predetermined divided layer A solidification step in which a solidified layer is formed by sintering or melting, a first temperature adjusting step in which at least a part of one or a plurality of solidified layers is a first temperature that is a predetermined temperature, and a first temperature. A second temperature adjusting step of setting at least a part of the one or more solidified layers to a second temperature that is a predetermined temperature, and the material layer forming step, the solidifying step, and the first temperature adjusting step. And the second temperature control step is repeatedly performed, and each of the first temperature control steps is performed. In the second temperature control step, the first temperature is T1, the second temperature is T2, the martensite transformation start temperature of the solidified layer is Ms, the martensite transformation end temperature of the solidified layer is Mf, and the tertiary that changes according to the application. Assuming that the minimum temperature at which the original model is exposed after modeling is Tm, in each of the first temperature control step and the second temperature control step,
All of the following relationships are satisfied:
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1 ≧ Ms (4)
T2> Mf (5)
T2 ≦ Tm (6)
Or all of the following relationships are satisfied,
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1 ≦ Ms (7)
T2> Mf (5)
T2 ≦ Tm (6)
A method for manufacturing a layered object is provided.

In the production method of engaging Ru product layer molded article of the present invention, the 3D object sets the second temperature below the minimum temperature that is exposed after molding. Thereby, since the temperature of a three-dimensional structure does not fall below 2nd temperature after modeling, the progress of unintended martensitic transformation can be suppressed and the quality of a three-dimensional structure is stabilized as a result.

It is a schematic block diagram of the additive manufacturing apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the irradiation unit which concerns on 1st Embodiment. It is a schematic block diagram of a 1st temperature control apparatus. It is a schematic block diagram of a 2nd temperature control apparatus. It is explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus which concerns on 1st Embodiment. It is explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus which concerns on 1st Embodiment. It is explanatory drawing of the additive manufacturing method using the additive manufacturing apparatus which concerns on 1st Embodiment. It is a schematic block diagram of the additive manufacturing apparatus which concerns on 2nd Embodiment. It is a schematic block diagram of the irradiation unit which concerns on 2nd Embodiment. It is explanatory drawing which shows the irradiation area | region in the additive manufacturing apparatus which concerns on 2nd Embodiment. It is explanatory drawing which shows the scanning method of the 1st beam and 2nd beam in the additive manufacturing apparatus which concerns on 2nd Embodiment. It is explanatory drawing which shows the scanning of the 1st beam and 2nd beam which include the predetermined site | part P in the scanning path | route in the additive manufacturing apparatus which concerns on 2nd Embodiment. It is the schematic of the temperature change in the temperature adjustment pattern (alpha). It is the schematic of the temperature change in the temperature adjustment pattern (beta).

  First, the structure of the additive manufacturing apparatus according to the present invention will be described. Even if it is other than the additive manufacturing apparatus specifically shown as the first embodiment and the second embodiment below, a material layer made of a metal material is formed, and a laser beam or an electron beam is formed on a predetermined portion of the material layer. If it is an additive manufacturing apparatus that forms a desired three-dimensional structure by stacking a plurality of sintered layers or molten layers by repeatedly irradiating a beam such as The present invention is applicable. In the following, solidification including sintering and melting is referred to as solidification, and the sintered layer and molten layer are referred to as solidification layer. In addition, various methods such as a powder sintering additive manufacturing method, a powder melt additive manufacturing method, an electron beam sintering method, an electron beam melting method, and a sheet lamination method are known as additive manufacturing methods. Any method may be used as long as it is applicable.

[First Embodiment]
Hereinafter, a first embodiment 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 first embodiment forms a material layer 63 made of a material powder, and irradiates a predetermined portion of the material layer 63 with the first beam L1 to sinter the material powder at the irradiation position. It is a layered manufacturing apparatus that stacks a plurality of solidified layers 65 to form a desired three-dimensional structure by repeating melting. As shown in FIG. 1, the additive manufacturing apparatus of the present invention includes a chamber 1, a material layer forming apparatus 2, an irradiation unit 3 </ b> A, and a cutting apparatus 4.

  A clean inert gas is supplied to the chamber 1 covering the required modeling region RM, and an inert gas containing fumes generated when the material layer 63 is sintered or melted is exhausted to have a predetermined concentration of inert gas. Filled with gas. An inert gas refers to a gas that does not substantially react with the material used, for example, nitrogen or argon.

  As shown in FIG. 1, in the chamber 1, a material layer forming apparatus 2 that forms a material layer 63 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 RM. Is provided. The material layer forming apparatus 2 includes a base table 21 having a modeling region RM, and a recoater head 23 that is arranged on the base table 21 and reciprocates in the horizontal uniaxial direction (arrow B direction). Blades are provided on both sides of the recoater head 23, respectively. The recoater head 23 reciprocates while discharging the material powder accommodated therein from the bottom, and the blade flattens the discharged material powder to form the material layer 63. In the modeling region RM, a modeling table 25 that can be moved in the vertical direction (arrow U direction) by the modeling table drive mechanism 27 is provided. When using the layered modeling apparatus, the modeling plate 61 is usually disposed on the modeling table 25, and the first material layer 63a is formed thereon. A powder holding wall 29 is provided around the modeling table 25. In the powder holding space surrounded by the powder holding wall 29 and the modeling table 25, unsolidified material powder is held. The modeling region RM is a region where a layered product can be formed, and the material layer 63 is formed in the modeling region RM. Further, the irradiation region RI is a region where the solidified layer 65 existing in the modeling region RM is formed, and approximately coincides with a region surrounded by the contour shape of a desired three-dimensional structure.

  An irradiation unit 3A is provided above the chamber 1. The irradiation unit 3A according to the first embodiment includes a first irradiation device 31 that forms a solidified layer by irradiating a predetermined irradiation region RI of the material layer 63 with a first beam L1 to sinter or melt, and a first beam. Scanning means 34 for scanning L1.

  As shown in FIG. 2, the first irradiation device 31 includes a first light source 311, a first collimator 313, and a first focus control unit 315. The first light source 311 outputs the first beam L1. Here, the first beam L1 is a laser beam capable of sintering or melting the material layer 63, and is, for example, a CO2 laser, a fiber laser, or a YAG laser. The first collimator 313 converts the first beam L1 output from the first light source 311 into parallel light. The first focus control unit 315 collects the first beam L1 output from the first light source 311 and adjusts it to a desired spot diameter.

  The scanning unit 34 is, for example, a galvano scanner, and the galvano scanner includes a pair of galvano mirrors 34x and 34y and actuators that rotate the galvano mirrors 34x and 34y, respectively. The biaxial galvanometer mirrors 34x and 34y scan the two-dimensionally controllable first beam L1 output from the first light source 311. The rotation angles of the galvanometer mirrors 34x and 34y are controlled according to the magnitude of a rotation angle control signal input from a control device (not shown). With this feature, the first beam L1 can be irradiated to a desired position by changing the magnitude of the rotation angle control signal input to each actuator of the galvanometer mirrors 34x and 34y.

  The first beam L1 that has passed through the galvanometer mirrors 34x and 34y passes through the protective window 11 provided in the upper portion of the chamber 1 and is irradiated onto the material layer 63 formed in the modeling region RM. Further, a pollution prevention device 13 is provided so as to cover the protective window 11. The contamination prevention device 13 is configured to fill the supplied inert gas under the protective window 11 and to eject the inert gas downward. Thus, fume is excluded from the path of the first beam L1, and contamination of the protective window 11 by fume is prevented.

  The cutting device 4 has a machining head 41 provided with a spindle head 43. The spindle head 43 can be rotated by attaching a cutting tool such as an end mill. The machining head 41 moves the spindle head 43 to a desired position in the chamber 1 by a machining head drive mechanism (not shown). Such a cutting device 4 can perform cutting on the surface of the solidified layer 65 and unnecessary portions.

Here, the additive manufacturing apparatus according to the first embodiment adjusts the temperature of at least a part of the solidified layer to at least one of the first temperature T1 that is a predetermined temperature or the second temperature T2 that is a predetermined temperature. An adjustment device is provided. In the following description, a solidified layer that is a target of temperature adjustment, that is, a solidified layer that has been formed and has not been subjected to temperature adjustment performed in the order of the first temperature T1 and the second temperature T2, is an upper surface layer. Call it. The temperature adjustment is not limited to an active temperature operation by the temperature adjustment device. For example, depending on the composition of the material, the temperature of the surrounding atmosphere may be an appropriate temperature as the first temperature T1 or the second temperature T2. In this case, the temperature adjusting device may adjust only one of the first temperature T1 and the second temperature T2. The temperature adjustment device according to the first embodiment adjusts the temperature of at least a part of the upper surface layer in the order of the first temperature T1 and the second temperature T2. Preferably, the temperature adjustment device according to the first embodiment adjusts the temperature of at least a part of the upper surface layer in the order of the first temperature T1, the second temperature T2, and the first temperature T1. In addition, in the 1st temperature T1, the 2nd temperature T2, the martensitic transformation start temperature Ms of the solidified layer 65, and the martensitic transformation end temperature Mf of the solidified layer 65, all the relations of the following formulas (1) to (3) are satisfied. It is.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
After sintering or melting, the upper surface layer before the temperature adjustment is in a state containing an austenite phase, and at least a part thereof is transformed into a martensite phase by the temperature adjustment.

  The temperature adjusting device may be configured such that the upper surface layer can be adjusted to at least one of the first temperature T1 and the second temperature T2. In particular, the temperature adjustment device has at least one of a heater that adjusts the upper surface layer to the first temperature T1 and a cooler that adjusts the upper surface layer to the second temperature T2, and preferably includes both. Below, the 1st temperature control apparatus 51 and the 2nd temperature control apparatus 52 are shown as a specific example of a temperature control apparatus.

  The first temperature adjustment device 51 includes a heater 51 a and a cooler 51 b provided inside the modeling table 25. The heater 51a is, for example, a conduit through which an electric heater or a heat medium is circulated. The cooler 51b is, for example, a conduit through which a heat medium is circulated. As the heat medium, various fluids such as water, oil, and liquid nitrogen can be used. As a specific configuration example, as shown in FIG. 3, the modeling table 25 includes a top plate 25a and three support plates 25b, 25c, 25d, and a heater 51a is provided between the top plate 25a and the support plate 25b. The cooler 51b is provided between the support plate 25c and the support plate 25d. The modeling table 25 can be adjusted to any temperature including the first temperature T1 and the second temperature T2 by the heater 51a and the cooler 51b. In order to prevent thermal displacement of the modeling table drive mechanism 27, a constant temperature part maintained at a constant temperature may be provided between the first temperature adjustment device 51 and the modeling table drive mechanism 27. By configuring the first temperature adjusting device 51 as described above, the upper surface layer is formed via the modeling plate 61 and the lower solidified layer 65 that are in contact with the top plate 51c of the modeling table 25 set to a desired temperature. It is possible to adjust to a desired temperature.

  The material layer 63 is preferably preheated to a predetermined temperature during sintering or melting, but the first temperature adjusting device 51 also serves as a preheating device for the material layer 63. For example, when the first temperature T1 is appropriate as the preheating temperature, the material layer 63 is preferably preheated to the first temperature T1 by the first temperature adjusting device 51.

  The second temperature adjusting device 52 shown in FIG. 4 includes a heater 52a that adjusts the upper surface layer from the upper side to the first temperature T1, and a cooler 52b that adjusts the upper surface layer from the upper side to the second temperature T2. Have. The heater 52a is, for example, a light heater such as a halogen lamp. The cooler 52b is, for example, a blower that blows the same kind of cooling gas as the inert gas that fills the chamber 1 onto the upper surface layer, or a cooling mechanism that makes a cooling plate cooled by a Peltier element contact the upper surface layer. . According to the second temperature adjusting device 52 as described above, the temperature of the upper surface layer can be directly adjusted, so that the temperature of the upper surface layer can be quickly adjusted even after the multiple solidified layers 65 are formed.

  As described above, the temperature adjusting device may be configured so that the temperature of the upper surface layer can be adjusted to at least one of the first temperature and the second temperature, and various forms can be adopted. For example, one or both of the first temperature adjusting device 51 and the second temperature adjusting device 52 may be provided as the temperature adjusting device. For example, the temperature adjustment device may include the heater 51a and the cooler 51b of the first temperature adjustment device 51 and the heater 52a and the cooler 52b of the second temperature adjustment device 52 in any combination. Other forms may be sufficient as a temperature control apparatus.

  As shown in FIG. 1, the additive manufacturing apparatus may include a temperature sensor 55 that measures the temperature of the upper surface layer, and the temperature adjustment apparatus may be feedback-controlled. With this configuration, the temperature of the upper surface layer can be controlled more accurately. A plurality of temperature sensors 55 may be provided. The temperature sensor 55 is, for example, an infrared temperature sensor.

  Here, each process in the manufacturing method of the layered object according to the first embodiment will be described with reference to FIGS. In the following, a step of forming the material layer 63 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 RM is a material layer forming step, and a predetermined irradiation of the material layer 63 The step of irradiating the region RI with the first beam L1 to sinter or melt to form the solidified layer 65 is a solidifying step, and the step of setting at least a part of the upper surface layer to a first temperature T1 that is a predetermined temperature is the first temperature. The adjusting step, the step of setting at least a part of the upper surface layer that has reached the first temperature T1 to the second temperature T2, which is a predetermined temperature, is referred to as a second temperature adjusting step. As described above, the temperature adjustment in the first temperature adjustment process and the second temperature adjustment process is not limited to the active temperature operation by the temperature adjustment device.

  As described above, the material layer 63 is preferably preheated to a predetermined temperature for solidification. Hereinafter, the step of preheating the material layer 63 before being irradiated with the first beam L1 is referred to as a preheating step. The preheating temperature is set to an appropriate temperature according to the type of material, but when the first temperature T1 is appropriate as the preheating temperature, the preheating temperature may be the first temperature T1. In this case, since the material layer 63 is at the first temperature T1 by the preheating process in advance, the time for raising the temperature to the first temperature T1 in the first temperature adjusting process can be shortened.

  First, the first material layer forming step is performed. As shown in FIG. 5, the modeling plate 61 is mounted on the modeling table 25, and the height of the modeling table 25 is adjusted to an appropriate position. In this state, the recoater head 23 filled with the material powder is moved in the arrow B direction to form the first material layer 63 a on the modeling plate 61. The first preheating step is performed after or in parallel with the material layer forming step. For example, the first material adjustment unit 51 preheats the first material layer 63a by adjusting the temperature of the modeling table 25 to a predetermined preheating temperature, here, the first temperature T1.

  Next, the first solidification step is performed. By irradiating a predetermined portion in the first material layer 63a with the first beam L1 and sintering or melting the laser irradiation position of the first material layer 63a, as shown in FIG. A solidified layer 65a is obtained.

  Subsequently, a second material layer forming step is performed. By lowering the height of the modeling table 25 by a predetermined thickness of the material layer 63 and moving the recoater head 23 in the direction of arrow B, the second material layer 63b is formed on the first solidified layer 65a. In addition, a preheating step is performed, and the second material layer 63b is preheated.

  Next, a second solidification step is performed. By irradiating a predetermined part in the second material layer 63b with the first beam L1 and sintering or melting the laser irradiation position of the second material layer 63b, as shown in FIG. A solidified layer 65b is obtained.

  By repeating the above steps, the third and subsequent solidified layers 65 are formed.

  The first temperature adjustment step is preferably performed in parallel with the above step. In the first embodiment, since the preheating temperature is the first temperature T1, the solidified layer 65 formed by the solidification process, that is, the upper surface layer is temperature-adjusted to the first temperature T1 by the temperature adjusting device, and the first temperature is maintained as it is. Maintained at T1. In other words, the preheating process for the material layer 63 and the first temperature adjustment process for the upper surface layer are performed together.

  When the predetermined number of solidified layers 65 are formed, the second temperature adjustment process is performed. The temperature adjusting device adjusts the temperature of the upper surface layer held at the first temperature T1 to the second temperature T2. In preparation for the next preheating step after the second temperature adjustment step, the temperature adjusting device adjusts the temperature of the upper surface layer to the preheating temperature, here the first temperature T1.

  In the additive manufacturing apparatus including the cutting device 4 as in the first embodiment, the cutting attached to the spindle head 43 with respect to the end surface of the solidified layer 65 every time a predetermined number of solidified layers 65 are formed. You may implement the cutting process which cuts with a tool. Preferably, a cutting process is implemented with respect to the upper surface layer after a 2nd temperature control process. By doing so, it is possible to cut the upper surface layer after the martensitic transformation has occurred and the dimensions have been stabilized, so that the cutting can be performed with higher accuracy. More preferably, the cutting process is performed on the upper surface layer that has been adjusted to room temperature after the second temperature adjustment step. In this way, the upper surface layer can be cut while suppressing the influence of expansion or contraction due to temperature, so that cutting can be performed with higher accuracy. In addition, spatter generated during sintering or melting may adhere to the surface of the solidified layer 65 to generate a protrusion, but when the blade of the recoater head 23 collides with the protrusion during the material layer forming process, Cutting may be performed on the upper surface of the uppermost solidified layer 65 in order to remove the protrusions.

  Such a material layer formation process, a preheating process, a solidification process, a 1st temperature control process, a 2nd temperature control process, and a cutting process are repeatedly implemented as needed, and a desired three-dimensional structure is formed. The first temperature control step and the second temperature control step may be performed every time when one solidified layer 65 is formed, may be performed every time a plurality of layers are formed, or according to the implementation of the cutting step. May be performed immediately before that. As described above, the first temperature adjustment step may be performed in parallel with other steps. Moreover, you may variably set the implementation period of a 1st temperature control process and a 2nd temperature control process according to the shape of a molded article, for example.

[Second Embodiment]
Next, a second embodiment 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. In addition, as shown in FIG. 8, the same code | symbol is attached | subjected to the structural member substantially equivalent to 1st Embodiment, and detailed description is abbreviate | omitted. Specifically, the chamber 1, the material layer forming device 2, and the cutting device 4 are the same as those in the first embodiment.

  An irradiation unit 3 </ b> B is provided above the chamber 1. As shown in FIG. 9, the irradiation unit 3B according to the second embodiment irradiates a predetermined irradiation region RI of the material layer 8 with a first beam L1 to sinter or melt to form a solidified layer 65. An irradiation device 31, a second irradiation device 32 for adjusting the first temperature T1, which is a predetermined temperature, by irradiating the solidified layer 65 formed by the first beam L1 with a second beam L2, a polarizing means 33, And scanning means 34 for scanning the first beam L1 and the second beam L2. The first irradiation device 31 includes a first light source 311, a first collimator 313, and a first focus control unit 315. The second irradiation device 32 includes a second light source 321 and a second collimator 323. In addition, you may provide another member as needed, for example, the 2nd irradiation apparatus 32 is the 2nd focus control unit which adjusts the 2nd beam L2 output from the 2nd light source 321 to a desired irradiation spot diameter. May be further provided.

  The first light source 311 outputs the first beam L1. Here, the first beam L1 is a laser beam capable of sintering or melting the material layer 63, and is, for example, a CO2 laser, a fiber laser, a YAG laser, or the like. The first collimator 313 converts the first beam L1 output from the first light source 311 into parallel light. The first focus control unit 315 collects the first beam L1 output from the first light source 311 and adjusts it to a desired spot diameter. Thereafter, the first beam L1 reaches the polarization means 33, and the polarized first beam L1, here reflected light, travels to the biaxial galvanometer mirrors 34x and 34y of the scanning means 34.

  The second light source 321 outputs the second beam L2. Here, the second beam L2 is a laser beam capable of adjusting the solidified layer 65, particularly the upper surface layer, to the first temperature T1, and is, for example, a CO2 laser, a fiber laser, a YAG laser, or the like. The second collimator 323 converts the second beam L2 output from the second light source 321 into parallel light. The second beam L2 reaches the polarization means 33, and the transmitted light travels to the biaxial galvanometer mirrors 34x and 34y of the scanning means 34.

  With the configuration as described above, the second beam L2 adjusts the upper surface layer to the first temperature T1. In other words, the third temperature adjustment device in the second embodiment includes the second irradiation device 32 that irradiates the upper surface layer formed by the first beam L1 with the second beam L2 to adjust to the first temperature T1. . Preferably, a fourth temperature adjustment device for adjusting the upper surface layer to the second temperature T2 is provided. The fourth temperature adjustment device includes, for example, a cooler provided in the modeling table 25 and capable of adjusting the upper surface layer to the second temperature T2. The cooler is, for example, a pipe line through which a heat medium flows.

  In the second embodiment, the second beam L2 is also used to preheat the material layer 63 before being irradiated with the first beam L1. When the second beam L2 is used for preheating, other preheating means are not essential. For example, the modeling table 25 may not be provided with a heater for preheating.

  Preferably, the irradiation spot of the second beam L2 is larger than the irradiation spot of the first beam L1, and is configured to surround the irradiation spot of the first beam L1. The irradiation spot means the irradiation position, in other words, the shape of the first beam L1 and the second beam L2 in the material layer 8 or the solidified layer 65. When the irradiation spot of the first beam L1 and the second beam L2 is substantially circular, if the irradiation spot diameter at the irradiation position of the first beam L1 is d1, and the irradiation spot diameter of the second beam L2 is d2, d2 / d1 is, for example, 10 ≦ d2 / d1 ≦ 1000. By such second beam L2, the material layer 63 is preheated before being irradiated with the first beam L1, and the solidified layer 65 that has been irradiated with the first beam L1 and solidified, that is, the upper surface layer is adjusted to the first temperature T1. Can be suitably performed.

  The polarization means 33 transmits one of the first beam L1 and the second beam L2 and polarizes the other in the same optical path as one. The polarization means 33 is a filter such as a beam splitter, for example. As described above, in the present embodiment, the first beam L1 polarized by the polarizing unit 33 and the second beam L2 transmitted through the polarizing unit 33 are converted into coaxial light and travel to the biaxial galvanometer mirrors 34x and 34y. Configured. With this configuration, it is possible to scan the first beam L1 and the second beam L2 with one scanning means 34 having substantially the same center position.

  As described above, the first beam L1 polarized by the polarizing means 33 and the second beam L2 transmitted through the polarizing means 33 become coaxial light and travel to the biaxial galvanometer mirrors 34x and 34y. The 1 irradiation apparatus 31 and the 2nd irradiation apparatus 32 were arrange | positioned. However, these are interchanged so that the first beam L1 transmitted through the polarizing means 33 and the second beam L2 polarized by the polarizing means 33 become coaxial light and travel to the biaxial galvanometer mirrors 34x and 34y. May be.

  The scanning unit 34 is, for example, a galvano scanner, and the galvano scanner includes a pair of galvano mirrors 34x and 34y and actuators that rotate the galvano mirrors 34x and 34y, respectively. The biaxial galvanometer mirrors 34x and 34y two-dimensionally scan the first beam L1 and the second beam L2 output from the first light source 311 and the second light source 321 in a controllable manner. The rotation angles of the galvanometer mirrors 34x and 34y are controlled according to the magnitude of a rotation angle control signal input from a control device (not shown). With this feature, the first beam L1 and the second beam L2 that have become coaxial light are irradiated to desired positions by changing the magnitude of the rotation angle control signal input to the actuators of the galvanometer mirrors 34x and 34y. Can do.

  The first beam L1 and the second beam L2 that have passed through the galvanometer mirrors 34x and 34y are transmitted through the protective window 11 provided in the upper portion of the chamber 1 and are applied to the material layer 63 formed in the modeling region RM.

  Here, a scanning method of the first beam L1 and the second beam L2 in the second embodiment will be described. In the present embodiment, as shown in FIG. 10, the irradiation region RI in each divided layer is divided into one or more divided regions for each predetermined width w, and the first beam L1 and the second beam L2 are scanned for each divided region. Is done. Specifically, as indicated by arrows in FIG. 11, scanning in the predetermined width w direction of the first beam L1 and the second beam L2 in the divided regions is sequentially performed along the scanning direction s orthogonal to the predetermined width w. . Since the irradiation spot of the second beam L2 is larger than the irradiation spot of the first beam L1 and the centers of the irradiation spots are substantially the same, the second beam L2 is second in comparison with the first beam L1 in each part on the irradiation region RI. The beam L2 is irradiated for a longer time. The scanning method of the first beam L1 and the second beam L2 described above is merely an example, and various scanning methods can be employed. 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 second embodiment is characterized in that the upper surface layer is adjusted to the first temperature T1 using at least the second irradiation device 32, and then the upper surface layer is adjusted to the second temperature T2. Also in the second embodiment, all the relationships of the following formulas (1) to (3) are satisfied.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
After the sintering or melting, the upper surface layer before being adjusted to the second temperature T2 is in a state containing an austenite phase, and at least a part thereof is transformed into a martensite phase when the second temperature T2 is reached. In the second embodiment, specifically, the upper surface layer is the uppermost solidified layer 65 at the time of a first temperature adjustment process described later.

  As described above, by configuring the second irradiation device 32 as the third temperature adjusting device, it is possible to adjust the upper surface layer to the first temperature T1. Further, the upper surface layer adjusted to the first temperature T1 is adjusted to the second temperature T2 by radiating heat to the lower solidified layer 65, the modeling plate 61, and the surrounding inert gas. In particular, when the fourth temperature adjusting device is provided as in the present embodiment, for example, when the modeling table 25 is temperature-adjusted to substantially the same temperature as the second temperature T2, the upper surface layer is more efficiently formed. It can be adjusted to 2 temperatures T2.

  The additive manufacturing apparatus may include a temperature sensor 55 that measures the temperature of the uppermost material layer 63 or the upper surface layer, and the temperature adjustment apparatus may be feedback controlled. For example, the scanning speed, laser intensity, and irradiation spot diameter of the second beam L2 may be feedback controlled. With this configuration, the temperature of the uppermost material layer 63 or the upper surface layer can be controlled more accurately. A plurality of temperature sensors 55 may be provided. The temperature sensor 55 is, for example, an infrared temperature sensor.

  Here, each process in the manufacturing method of the layered object according to the second embodiment will be described. The definitions of the material layer forming step, the preheating step, the solidifying step, the first temperature adjusting step, the second temperature adjusting step, and the cutting step are as described above. In particular, in the second embodiment, the preheating step and the first temperature adjustment step are performed by the second beam L2.

  First, a material layer forming step is performed. A material layer 63 is formed by the recoater head 23 on the modeling plate 61 or the solidified layer 65 on the modeling table 25 adjusted to an appropriate position.

  Next, a preheating step, a solidification step, a first temperature adjustment step, and a second temperature adjustment step are performed. The preheating step, the solidification step, the first temperature adjustment step, and the second temperature adjustment step are performed in parallel. However, if attention is paid to a certain part, the preheating step, the solidification step, the first temperature adjustment step, and the second temperature adjustment step are performed. It is done in order. Here, attention should be paid to the predetermined portion P in FIG. FIG. 12 schematically shows scanning of the first beam L1 and the second beam L2 in the predetermined width w direction including the predetermined portion P in the scanning path.

  In the state shown in FIG. 12A, the predetermined beam P of the material layer 63 is not irradiated with the first beam L1 and the second beam L2. Here, the first preheating step is performed at the predetermined portion P. As shown in FIG. 12B, the first beam L1 and the second beam L2 are scanned, and the second portion L2 is irradiated to the predetermined portion P. As a result, the predetermined portion P is preheated to a temperature suitable for solidification. The second beam L2 is applied before scanning the first beam L1 and the second beam L2 in the divided regions until the temperature of the material layer 63 in the vicinity of the starting point of scanning in each divided region is increased to a temperature suitable for solidification. It is desirable to irradiate the material layer 63 near the starting point for a predetermined time.

  Next, a solidification step is performed at the predetermined portion P. That is, as shown in FIG. 12 (c), the predetermined portion P in the material layer 63 is irradiated with the first beam L1, and the laser irradiation position of the material layer 63 is sintered or melted. That is, the predetermined part P becomes a part of the solidified layer 65.

  Next, the first temperature adjustment step is performed at the predetermined portion P. As shown in FIG. 12D, the predetermined beam P that has become the solidified layer 65 is irradiated with the second beam L2. The predetermined part P reaches at least the first temperature T1 by irradiation with the second beam L2. Note that the first beam L1 and the second beam L2 are irradiated until the second beam L2 is sufficiently irradiated so that the martensite transformation occurs when the solidified layer 65 near the end point of scanning in each divided region is adjusted to the second temperature T2. It is desirable that the solidified layer 65 near the end point is irradiated with the second beam L2 for a predetermined time after the beam L2 finishes scanning in the divided area. In addition, the time for which the first temperature T1 is held in the first temperature control step and the first temperature T1 are set to appropriate values according to the metal material used or the metal material assumed to be used. It can be adjusted by the scanning speed of the beam L2, the laser intensity, and the irradiation spot diameter.

  As shown in FIG. 12E, after the irradiation of the predetermined part P by the second beam L2 is completed, the second temperature adjustment process is performed in the predetermined part P. The predetermined portion P is deprived of heat by the lower solidified layer 65, the modeling plate 7, an inert gas atmosphere, etc., and becomes the second temperature T2.

  Such a material layer forming step, a preheating step, a solidifying step, a first temperature adjusting step, a second temperature adjusting step, and a cutting step that is preferably inserted as appropriate are repeated to form a desired three-dimensional structure. In the above manufacturing method, the preheating step, the solidification step, the first temperature adjustment step, and the second temperature adjustment step were performed in parallel. However, in each part, the preheating step, the solidification step, the first temperature adjustment step, and the second temperature adjustment step were performed. If each process is performed in the order of the temperature control process, the preheating process, the solidification process, the first temperature control process, and the second temperature control process may not be performed in parallel. For example, the first temperature adjustment step and the second temperature adjustment step may be performed every time the solidification step related to the formation of one or more solidified layers 65 is completed. In this case, the upper surface layer is the one or more solidified layers 65 including at least the uppermost solidified layer at the time of the first temperature adjustment step.

[Temperature pattern]
As specifically exemplified as the first embodiment and the second embodiment, by performing additive manufacturing while repeatedly performing the temperature adjustment including the first temperature adjustment step and the second temperature adjustment step, the martensite transformation is performed. It is possible to reduce the tensile stress caused by the shrinkage due to cooling of the solidified layer 65 by the volume expansion of the solidified layer 65 and to suppress the deformation of the modeled object. In other words, the first temperature adjustment step and the second temperature adjustment step can be performed a plurality of times during the modeling, and the solidified layer can be laminated while reducing the tensile stress.

  The temperature range where martensitic transformation occurs is not more than martensitic transformation start temperature Ms and not less than martensitic transformation end temperature Mf. That is, the amount of expansion due to martensitic transformation, and thus the residual stress of the shaped article, can be controlled by the relationship between the first temperature T1, the second temperature T2, the martensitic transformation start temperature Ms, and the martensitic transformation end temperature Mf. . Further, as described above, when the second temperature T2 is included in the temperature range in which martensitic transformation occurs, the martensitic transformation is further performed when the temperature of the modeled object becomes lower than the second temperature T2 after the modeling is completed. It may progress and unintentional expansion may occur. Therefore, the second temperature T2 is set to be equal to or lower than the minimum temperature Tm at which the three-dimensional structure is exposed after modeling. If it does in this way, since the temperature of a modeling thing will not become less than 2nd temperature after modeling, it can control that a martensitic transformation advances after modeling.

  That is, when the second temperature T2 is included in the temperature range in which martensitic transformation occurs, the temperature adjustment patterns shown in FIGS. 13 and 14 are appropriate. 13 and 14, the temperature change in the first embodiment, that is, the solidified layer 65 in the predetermined divided layer is solidified, and then the temperature is adjusted in the order of the first temperature T1, the second temperature T2, and the first temperature T1. The temperature change is schematically displayed. The temperature change at each time point in the first embodiment will be specifically described. First, the material layer 63 is irradiated with the first beam L1, and the solidified layer 65 is formed. Immediately after formation, the heat of the solidified layer 65 is taken away by the lower solidified layer 65, the modeling plate 61, etc., and the temperature of the solidified layer 65 is maintained at the first temperature T1 (t1). When the predetermined solidified layer 65 is formed (t2), the solidified layer 65 is adjusted to the second temperature T2 (t3). After the temperature adjustment to the second temperature T2 is completed (t4), the solidified layer 65 is again heated to the first temperature T1 (t5). Note that, as described above, the temperature of the predetermined portion of the solidified layer 65 may be adjusted at least in the order of the first temperature T1 and the second temperature T2, and thus the present disclosure is limited to the temperature change illustrated in FIGS. It is not something. 13 and 14 are only reference diagrams for visually displaying each relational expression. Further, the same pattern may be applied to the solidified layers 65 related to all the divided layers, but different patterns may be individually applied to the solidified layers 65 related to the respective divided layers.

<Pattern α>
In the pattern α, the following expressions (1), (2), (3), (4), (5) and (6) are all satisfied. FIG. 13 shows a schematic diagram of the temperature change of the predetermined solidified layer 65 having the pattern α.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1 ≧ Ms (4)
T2> Mf (5)
T2 ≦ Tm (6)
In the pattern α, it is not necessary to consider the influence of the temperature increase of the solidified layer 65 due to the irradiation of the first beam L1, and the modeling can proceed with the residual stress suppressed, and the compression is performed by lowering the temperature after the modeling is completed. Stress can be generated. Generation of cracks can be suppressed by leaving an appropriate compressive stress in the molded article. This is a control method suitable for a material whose expansion due to martensitic transformation is sufficiently larger than the contraction during molding.

<Pattern β>
In the pattern β, the following expressions (1), (2), (3), (5), (6) and (7) are all satisfied. Further, FIG. 14 shows a schematic diagram of the temperature change of the predetermined solidified layer 65 of the pattern β.
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1 ≦ Ms (7)
T2> Mf (5)
T2 ≦ Tm (6)
In the pattern β, when the temperature can be accurately controlled, it is possible to control the residual stress during the modeling and after the modeling is completed and the temperature is lowered. This is a control method suitable for a material whose expansion due to martensitic transformation is sufficiently larger than the contraction during molding.

[material]
Each of the above-mentioned temperature patterns is limited in applicable materials. For example, when the temperature of the pattern α is adjusted, at least the martensitic transformation start temperature Ms needs to be included in the range in which the temperature can be controlled by the temperature adjusting device, but all materials satisfy the condition. is not. On the other hand, it is known that the martensite transformation start temperature Ms and the martensite transformation end temperature Mf rise and fall 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 desired martensite transformation start temperature is obtained by mixing at least one of the second metal, which is another metal having a relatively high carbon content, or carbon with the first metal, which is the predetermined metal. A mixed material having Ms or a martensite transformation end temperature Mf may be generated.
[Other variations]

  The additive manufacturing apparatus according to the first embodiment and the second embodiment is an additive manufacturing apparatus using a powder sintering additive manufacturing method or a powder fusion additive manufacturing method. Good. In the sheet lamination method, the material layer forming apparatus uses a plate-like metal sheet 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 RM. Form. That is, a configuration may be adopted in which a material layer is formed using a plate-shaped 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 beam L1. Good.

  In the first and second embodiments, laser light is used as the first beam L1, but other configurations may be used as long as the solidified layer 65 can be formed. For example, the first beam L1 is an electron beam. There may be. In the second embodiment, laser light is used as the second beam L2, but other configurations may be used as long as the solidified layer 65 can be adjusted to the first temperature T1, for example, the second beam L2 is an electron beam. It may be.

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 T1 and the second temperature T2 may not be constant during modeling. For example, the specific numerical values of the first temperature T1 and the second temperature T2 may change for each first temperature adjustment step or second temperature adjustment step.

  As mentioned above, although embodiment and the modification of this invention were demonstrated, these are shown as an example and are not intending limiting the range of 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. In particular, the technical features shown in the first embodiment and the second embodiment can be combined with each other as long as there is no technical contradiction. These embodiments and modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

2 Material layer forming device 31 First irradiation device 63 Material layer 65 Solidified layer L1 First beam RI Irradiation region RM Modeling region

Claims (1)

A step of setting a second temperature, which is a predetermined temperature, to a temperature equal to or lower than a minimum temperature at which the three-dimensional structure that changes according to the application is exposed after modeling;
A material layer forming 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 the modeling region;
A solidification step of irradiating a predetermined irradiation region of the material layer in the predetermined divided layer with a first beam to sinter or melt to form a solidified layer;
A first temperature adjusting step of setting at least a part of the solidified layer of one or more layers to a first temperature that is a predetermined temperature;
A second temperature adjusting step of bringing the at least part of the one or more solidified layers that have reached the first temperature into the second temperature,
The material layer forming step, the solidifying step, the first temperature adjusting step and the second temperature adjusting step are repeatedly performed,
In each of the first temperature control step and the second temperature control step, 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 of the solidified layer is performed. Assuming that the end temperature is Mf, and the minimum temperature at which the three-dimensional structure that changes according to the application is exposed after modeling is Tm,
In each of the first temperature control step and the second temperature control step,
All of the following relationships are satisfied:
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1 ≧ Ms (4)
T2> Mf (5)
T2 ≦ Tm (6)
Or all of the following relationships are satisfied,
T1 ≧ Mf (1)
T1> T2 (2)
T2 ≦ Ms (3)
T1 ≦ Ms (7)
T2> Mf (5)
T2 ≦ Tm (6)
Manufacturing method of layered object.

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