Three-dimensional modeling device and abnormality detection device

Abstract

To accurately detect abnormality of unevenness on a surface of a powder bed.SOLUTION: A three-dimensional modeling device 1 comprises: a supply unit 35 for forming a powder bed PA on a main surface 6a of a table 6 by supplying powder P onto the main surface 6a; an irradiation unit 33 for obtaining a three-dimensional object M in which the powder P is solidified by irradiating the powder bed PA with an electron beam; an abnormality detection unit 34 for detecting that an unevenness of an application surface PB of the powder bed PA irradiated with the electron beam is not within an allowable range. The abnormality detection unit 34 comprises: a first detection plate 42A that faces the application surface PB in a normal direction D1; a second detection plate 42B configured to be displaced from a position separated from the first detection plate 42A in the normal direction D1 to a position in contact with the first detection plate 42A; and a continuity detection unit 43 for detecting continuity between the first detection plate 42A and the second detection plate 42B when the second detection plate 42B contacts the first detection plate 42A according to a force acting in the normal direction D1.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a three-dimensional printing apparatus and an abnormality detection apparatus. [Background technology]

[0002] Patent Documents 1 to 3 disclose techniques related to three-dimensional modeling devices. Three-dimensional modeling devices create three-dimensional objects by repeating an operation of laying powder such as metal in layers and an operation of solidifying the powder by irradiating it with an energy beam. In a three-dimensional modeling device, when solidifying the powder by irradiating it with an energy beam, an unintended large protruding solidified object (protrusion) may be formed on the surface of the powder bed. Such protrusions may cause problems such as interference with a coating mechanism for laying the powder in layers. Therefore, in order to avoid interference between the protrusions and the coating mechanism, it is conceivable to detect the presence of the protrusions as an abnormality in the unevenness of the surface of the powder bed. For example, Patent Document 1 discloses a three-dimensional modeling device equipped with a contact detection sensor for detecting such protrusions.

[0003] The contact detection sensor disclosed in Patent Document 1 detects the presence or absence of a protrusion to be detected (hereinafter referred to as a "target protrusion") while moving horizontally on the surface of the powder bed. The contact detection sensor has a pair of leaf springs that extend vertically on the surface of the powder bed and are arranged at a distance in the moving direction of the contact detection sensor, and a continuity sensor that detects the conduction between the pair of leaf springs. The lower ends of the pair of leaf springs are maintained at a height that interferes with the target protrusion. When the contact detection sensor moves horizontally in this state, when the pair of leaf springs collide with the target protrusion, one leaf spring is displaced so as to bend toward the other leaf spring. Then, when one leaf spring contacts the other leaf spring, the continuity sensor detects the conduction between the pair of leaf springs, and the contact detection sensor detects that the target protrusion is present on the surface of the powder bed, that is, that the unevenness of the surface of the powder bed is abnormal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-026577 A [Patent Document 2] JP 2004-277881 A [Patent Document 3] JP 2007-100199 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned contact detection sensor, in order to accurately detect the target protrusion, the height of the lower ends of the pair of leaf springs, i.e., the vertical distance between the surface of the powder bed and the pair of leaf springs, is important. However, in a high-temperature environment during molding, the vertical dimensions of the pair of leaf springs are likely to change significantly due to the influence of thermal expansion. If the vertical dimensions of the pair of leaf springs change significantly, the vertical distance between the surface of the powder bed and the pair of leaf springs changes significantly accordingly, so that there is a possibility that even allowable protrusions that do not need to be detected will be detected. Therefore, it is difficult for the above-mentioned contact detection sensor to accurately detect the target protrusion, i.e., to accurately detect abnormalities in the unevenness of the surface of the powder bed.

[0006] The present disclosure describes a three-dimensional modeling apparatus and an anomaly detection apparatus capable of detecting irregularities in the surface of a powder bed with high accuracy. [Means for solving the problem]

[0007] A three-dimensional modeling apparatus according to one embodiment of the present disclosure includes a supply unit that supplies powder onto a main surface of a table to form a powder bed, which is a layer of powder, on the main surface; an irradiation unit that irradiates the powder bed with an energy beam to obtain a three-dimensional object in which the powder has solidified; and an abnormality detection unit that detects whether the unevenness of the surface of the powder bed irradiated with the energy beam is outside of an acceptable range. The abnormality detection unit has a first conductor that faces the surface in a normal direction to the main surface, a second conductor that is arranged between the surface and the first conductor in the normal direction and is configured to displace from a position spaced apart from the first conductor in the normal direction to a position in contact with the first conductor, and a continuity detection unit that detects continuity between the first conductor and the second conductor when the second conductor contacts the first conductor in response to a force acting in the normal direction.

[0008] An anomaly detection device according to one embodiment of the present disclosure is an anomaly detection device for detecting that unevenness on the surface of a powder bed irradiated with an energy beam on a main surface of a table is not within an acceptable range, and includes a first conductor facing the surface in a normal direction to the main surface, a second conductor arranged between the surface and the first conductor in the normal direction and configured to displace from a position spaced apart from the first conductor in the normal direction to a position in contact with the first conductor, and a continuity detection unit that detects continuity between the first conductor and the second conductor when the second conductor contacts the first conductor in response to a force acting in the normal direction.

[0009] In the above-mentioned three-dimensional modeling device and anomaly detection device, when a protrusion that is not within the allowable range (hereinafter referred to as a "target protrusion") is present on the surface of the powder bed, the second conductor is displaced in the normal direction by the force received from the target protrusion and comes into contact with the first conductor. At this time, the conduction detection unit detects the conduction between the first conductor and the second conductor. Therefore, when the conduction detection unit detects the conduction between the first conductor and the second conductor, it can detect that the unevenness of the surface of the powder bed is not within the allowable range, that is, that the unevenness of the surface of the powder bed is abnormal. In this way, when the first conductor and the second conductor are arranged side by side in the normal direction, the influence of the dimensional change of the first conductor and the second conductor due to thermal expansion on the abnormality detection accuracy of the unevenness of the surface of the powder bed can be reduced compared to the case where these conductors are arranged side by side along the surface of the powder bed so as to stand upright against the surface of the powder bed. Therefore, in the above-mentioned configuration, even if the dimensions of the first conductor and the second conductor change due to thermal expansion, it is possible to suppress a situation in which the positions of the first conductor and the second conductor change significantly in the normal direction with respect to the surface of the powder bed. In other words, even in a high-temperature environment, the distance between the first conductor, the second conductor, and the surface of the powder bed can be maintained. This allows the target protrusion to be detected with high accuracy. As a result, it becomes possible to detect abnormalities in the unevenness of the surface of the powder bed with high accuracy.

[0010] In some embodiments, the abnormality detection unit may further include an abnormality determination unit that, when the continuity detection unit detects continuity between the first conductor and the second conductor, determines that the unevenness of the surface of the powder bed is not within an acceptable range and determines that the unevenness of the surface of the powder bed is in an abnormal state. In this case, the state in which the first conductor and the second conductor are in conduction can be determined as a state in which the unevenness of the surface of the powder bed is abnormal.

[0011] In some embodiments, the second conductor is a conductive plate whose thickness direction is the normal direction, and may have a curved portion that curves toward the surface in the normal direction. In this case, the presence of the curved portion makes it easy to adjust the distance between the second conductor and the surface of the powder bed. As a result, it becomes possible to detect the target protrusion with higher accuracy.

[0012] In some embodiments, the first conductor and the second conductor are movable relative to the surface in the scanning direction along the main surface, and the curved portion may have an arc shape that is convex toward the surface in a cross section along the normal direction and the scanning direction. In this configuration, when a target protrusion is present on the surface of the powder bed, the curved portion of the second conductor is more likely to be displaced in the normal direction by receiving a force from the target protrusion. As a result, when a target protrusion is present on the surface of the powder bed, the second conductor can be more reliably brought into contact with the first conductor. In other words, it is possible to more reliably detect the target protrusion.

[0013] In some embodiments, the curved portion may be configured to elastically deform from a position spaced apart from the first conductor to a position in contact with the first conductor, which can easily realize a configuration in which the second conductor is displaced from a position spaced apart from the first conductor to a position in contact with the first conductor.

[0014] In some embodiments, the three-dimensional modeling apparatus may further include an insulating support that supports the first and second conductors, and both ends of the second conductor may be supported by the support, and a portion between both ends of the second conductor may form a curved portion. In this case, it is possible to easily form the second conductor having a curved portion while ensuring electrical insulation between the first and second conductors.

[0015] In some embodiments, the three-dimensional printing apparatus further includes a third conductor disposed between the surface and the second conductor in a normal direction and configured to be displaced from a position spaced apart from the second conductor in the normal direction to a position in contact with the second conductor, and the continuity detection unit may output a first continuity detection signal indicating that continuity between the third conductor and the second conductor has been detected when the third conductor contacts the second conductor in response to a force acting in the normal direction, and may output a second continuity detection signal indicating that continuity between the second conductor and the first conductor has been detected when the second conductor contacts the first conductor in response to a force acting in the normal direction. In this case, it is possible to detect the height of a target protrusion present on the surface of the powder bed in stages depending on the continuity state between the first conductor, the second conductor, and the third conductor.

[0016] In some embodiments, the abnormality detection unit further includes an abnormality determination unit that determines that the surface unevenness of the powder bed is not within an acceptable range and determines that the surface unevenness of the powder bed is in an abnormal state when the continuity detection unit detects continuity between the first conductor, the second conductor, and the third conductor, and the abnormality determination unit may determine that the surface unevenness of the powder bed is in a first abnormal state when the continuity detection unit outputs only the first continuity detection signal, and may determine that the surface unevenness of the powder bed is in a second abnormal state different from the first abnormal state when the continuity detection unit outputs both the first continuity detection signal and the second continuity detection signal. In this configuration, when the continuity detection unit outputs only the first continuity detection signal, it can be determined that a target protrusion of a height that does not reach at least the first conductor is present on the surface of the powder bed (first abnormal state). On the other hand, when the continuity detection unit outputs both the first continuity detection signal and the second continuity detection signal, it can be determined that a higher target protrusion is present on the surface of the powder bed (second abnormal state) than when the continuity detection unit outputs only the first continuity detection signal. Thus, according to the above-mentioned configuration, it is possible to detect the abnormal state of unevenness on the surface of the powder bed in stages depending on the conduction state between the first conductor, the second conductor, and the third conductor.

[0017] In some embodiments, the third conductor is a conductive plate whose thickness direction is the normal direction, and may have a curved portion curved toward the surface in the normal direction. In this case, the presence of the curved portion makes it easy to adjust the distance between the third conductor and the surface of the powder bed. As a result, it becomes possible to detect the target protrusion with higher accuracy.

[0018] In some embodiments, the three-dimensional modeling apparatus further includes a control unit that controls the operation of the supply unit and the irradiation unit, and when the abnormality determination unit determines that the surface unevenness is in a first abnormal state, the control unit causes the supply unit and the irradiation unit to execute a recovery operation to eliminate the abnormality in the surface unevenness, and when the abnormality determination unit determines that the surface unevenness is in a second abnormal state, the control unit may stop the operation of the supply unit and the irradiation unit. In this way, by taking an appropriate response according to the abnormal state of the surface unevenness of the powder bed, the modeling process can be reliably performed in a normal state. Effect of the Invention

[0019] According to some aspects of the present disclosure, there is provided a three-dimensional printing apparatus and an anomaly detection apparatus capable of detecting irregularities in the surface of a powder bed with high accuracy. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a cross-sectional view showing a three-dimensional modeling apparatus according to an embodiment. [Diagram 2] FIG. 2 is a plan view showing a processing section of the three-dimensional modeling apparatus of FIG. [Diagram 3] FIG. 3 is a block diagram showing the configuration of a control unit of the three-dimensional modeling apparatus of FIG. [Figure 4] FIG. 4 is a cross-sectional view showing an abnormality detection unit of the three-dimensional modeling apparatus of FIG. [Diagram 5] Fig. 5(a) is a cross-sectional view showing a state in which the second detection plate and the third detection plate are electrically connected in the cross section shown in Fig. 4. Fig. 5(b) is a cross-sectional view showing a state in which the first detection plate, the second detection plate, and the third detection plate are all electrically connected in the cross section shown in Fig. 4. [Figure 6] FIG. 6 is a flow diagram showing the operation performed by the control unit when forming one layer of a modeled object. [Figure 7] FIG. 7 is a flow diagram showing details of the recovery operation shown in FIG. [Figure 8] Fig. 8(a) is a diagram for explaining a problem with a conventional anomaly detection unit, and Fig. 8(b) is a diagram for explaining an effect achieved by an anomaly detection unit according to an embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a modified example of the anomaly detection unit. [Figure 10] Fig. 10(a) is a cross-sectional view showing a state in which the second detection plate and the third detection plate are electrically connected in the cross section shown in Fig. 9. Fig. 10(b) is a cross-sectional view showing a state in which the first detection plate, the second detection plate, and the third detection plate are all electrically connected in the cross section shown in Fig. 9. [Figure 11] FIG. 11 is a cross-sectional view showing another modified example of the anomaly detection unit. [Figure 12] Fig. 12(a) is a cross-sectional view showing a state in which the second detection plate and the third detection plate are electrically connected in the cross section shown in Fig. 11. Fig. 12(b) is a cross-sectional view showing a state in which the first detection plate, the second detection plate, and the third detection plate are all electrically connected in the cross section shown in Fig. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0022] The three-dimensional modeling apparatus 1 shown in FIG. 1 is a so-called 3D printer. The three-dimensional modeling apparatus 1 employs an electron beam as an energy beam. In other words, the three-dimensional modeling apparatus 1 employs a so-called electron gun powder bed fusion method. The three-dimensional modeling apparatus 1 uses a powder P to model a three-dimensional object M. The three-dimensional modeling apparatus 1 first supplies the powder P onto a table. Then, the three-dimensional modeling apparatus 1 irradiates the powder P with an electron beam. The powder P irradiated with the electron beam is melted or sintered. Then, when the three-dimensional modeling apparatus 1 stops irradiating the electron beam, the temperature of the powder P drops, and the powder P solidifies. The three-dimensional modeling apparatus 1 repeats this process of irradiating and stopping the electron beam to model a three-dimensional object M.

[0023] The molded object M is, for example, a machine part. The molded object M may be another structure. The powder P is composed of a large number of powder bodies. The powder P is, for example, a metal powder. Examples of the metal powder include titanium-based metal powder, Inconel (registered trademark) powder, and aluminum powder. The powder P is not limited to a metal powder. The powder P may be, for example, a resin powder, or a powder containing carbon fiber and resin, such as CFRP (Carbon Fiber Reinforced Plastics). The powder P may be another powder having electrical conductivity. The powder P does not need to be electrically conductive. For example, when a laser is used as the energy beam, the powder P does not need to be electrically conductive.

[0024] As shown in FIG. 1, the three-dimensional printing apparatus 1 includes a housing 5, a driving unit 10, a modeling processing unit 30, and a control unit 50. The housing 5 is supported by a plurality of columns. The housing 5 forms a modeling space S. The modeling space S is an airtight space that can be decompressed for processing the powder P by the modeling processing unit 30. A table 6 and a modeling tank 7 are arranged in the modeling space S. The table 6 is a processing stage on which modeling processing is performed. The table 6 has, for example, a disk shape, and is installed so as to be rotatable about a rotation axis C. The rotation axis C is set, for example, along the vertical direction. The powder P, which is a raw material of the model M, is arranged on a main surface 6a of the table 6. The main surface 6a of the table 6 is a modeling surface (upper surface) on which the model M is formed. The main surface 6a is arranged so as to be perpendicular to the rotation axis C. In other words, the normal direction D1 of the main surface 6a coincides with the direction in which the rotation axis C extends.

[0025] In the following description, the terms "upper" and "lower" are used based on the state in which the normal direction D1 is aligned vertically. In the state in which the normal direction D1 is aligned vertically, the term "lower" refers to the ground side in the vertical direction, and the term "upper" refers to the opposite side from the ground in the vertical direction. In addition, the "circumferential direction D2" refers to a direction along a ring centered on the rotation axis C. The "circumferential direction D2" includes the rotation direction D21 in which the table 6 rotates around the rotation axis C. The "radial direction" refers to a direction perpendicular to the rotation axis C. In this embodiment, the "circumferential direction D2" and the "radial direction" are directions along the surface direction along the main surface 6a of the table 6. In other words, the "circumferential direction D2" and the "radial direction" are included in the surface direction of the main surface 6a. The "surface direction" here may be any direction along the main surface 6a of the table 6, and also includes directions other than the "circumferential direction D2" and the "radial direction".

[0026] The driving unit 10 realizes various operations required for modeling. For example, the driving unit 10 rotates and raises and lowers the table 6. The driving unit 10 has a rotation unit 11 and a lifting unit 12. The rotation unit 11 rotates the table 6 about a rotation axis C. The upper end of the rotation unit 11 is connected to the table 6, and the lower end of the rotation unit 11 is connected to a drive source (e.g., a motor). The lifting unit 12 raises and lowers the table 6. This raising and lowering is performed along the normal direction D1.

[0027] The formation processing unit 30 processes the powder P to obtain a formed object M. The processing of the powder P includes, for example, a supplying process of the powder P, a preheating process of the powder P (preliminary heating process), a forming process of the powder P, and an abnormality detection process of the powder P. The formation processing unit 30 is disposed above the main surface 6a of the table 6, and is disposed at a position facing the main surface 6a in a normal direction D1. As shown in FIG. 2, the formation processing unit 30 has, for example, a first formation processing unit 31A and a second formation processing unit 31B. The first formation processing unit 31A and the second formation processing unit 31B are disposed side by side along a circumferential direction D2. The first formation processing unit 31A and the second formation processing unit 31B are, for example, at positions rotationally symmetrical by 180° with respect to the rotation axis C. The first formation processing unit 31A and the second formation processing unit 31B have, for example, the same components as each other.

[0028] Hereinafter, unless there is a need to distinguish between the first formation processing unit 31A and the second formation processing unit 31B, they will be collectively referred to simply as the "formation processing unit 31." Note that the first formation processing unit 31A and the second formation processing unit 31B may have different components. For example, the components of one of the first formation processing unit 31A and the second formation processing unit 31B may be a part of the components of the other.

[0029] The modeling processing unit 31 includes, for example, a heating section 32, an irradiation section 33, an anomaly detection section 34 (anomaly detection device), and a supply section 35. The supply section 35 supplies the powder P onto the main surface 6a of the table 6. The supply section 35 includes a raw material tank and a powder application mechanism. The raw material tank stores the powder P and supplies the powder P onto the main surface 6a of the table 6. The powder application mechanism smoothes the surface (upper surface) of the top layer of the stack of the powder P supplied onto the main surface 6a of the table 6. Hereinafter, this stack of the powder P is referred to as the "powder bed PA." The "powder bed PA" here refers to both the stack of the powder P before it is irradiated with the electron beam and the stack including the solidified material of the powder P formed by the irradiation of the electron beam. The powder application mechanism is, for example, a rod-shaped or plate-shaped member, and is arranged so as to extend in the radial direction on the main surface 6a of the table 6. For example, a recoater, a roller, a rod-shaped member, or a brush unit can be used as the powder application mechanism. The powder application mechanism contacts the surface of the powder bed PA and spreads it evenly as the table 6 rotates. In this way, the powder bed PA is applied to the main surface 6a with a uniform thickness. Hereinafter, the surface of the powder bed PA applied to the main surface 6a will be referred to as the "application surface PB."

[0030] The heating unit 32 preheats (preliminarily heats) the powder bed PA applied on the main surface 6a. The heating unit 32 increases the temperature of the powder bed PA, for example, by radiant heat. The heating unit 32 may be, for example, an infrared heater or a heater that heats by another method. Note that "preheating" here means heating so that the temperature of the powder P in the preheating region is higher than the temperature of the powder P in the supply region.

[0031] The irradiation unit 33 irradiates the preheated powder bed PA with an electron beam. The irradiation unit 33 is, for example, an electron gun. The irradiation unit 33 generates an electron beam according to the potential difference generated between the cathode and the anode. Then, the irradiation unit 33 irradiates the electron beam, which is converged by adjusting the electric field, to a desired position of the powder bed PA. The electron beam heats the powder P in the powder bed PA. That is, the irradiation unit 33 imparts energy to the powder P. As a result, the powder P is heated and melted or sintered. The heating temperature of the powder P at this time is higher than the preheating temperature of the powder P by the heating unit 32, and is a temperature at which the molded object M can be formed (i.e., the sintering temperature or melting temperature). Then, when the irradiation unit 33 stops irradiating the powder P with the electron beam, the temperature of the powder P drops, and the powder P solidifies. As the table 6 rotates, irradiation and stopping of the electron beam on the powder P are repeated multiple times, thereby forming the molded object M.

[0032] The abnormality detection unit 34 detects an abnormality in the unevenness of the coating surface PB of the powder bed PA irradiated with the electron beam. The state in which there is an abnormality in the unevenness of the coating surface PB means a state in which the unevenness of the coating surface PB is not within an acceptable range. The state in which the unevenness of the coating surface PB is not within an acceptable range means a state in which the height (degree) of the unevenness of the coating surface PB is not within a certain acceptable range, more specifically, a state in which an unintended large protrusion (i.e., a protrusion having a height outside the acceptable range) is present on the coating surface PB. An unintended large protrusion is, for example, a large warped portion of the model M that occurs when the powder P is irradiated with the electron beam. The melting and solidification of the powder P by the irradiation of the electron beam is accompanied by thermal deformation due to the material properties of the powder P. At this time, the model M may be significantly warped upward from the coating surface PB due to unintended thermal stress.

[0033] If such a large protrusion (i.e., a warped portion of the model M) is present on the coating surface PB, the supply unit 35 may come into contact with the protrusion, hindering the operation of the supply unit 35, making it difficult for the three-dimensional modeling device 1 to perform the modeling process normally. Therefore, when the abnormality detection unit 34 detects a large protrusion to be detected (hereinafter referred to as a "target protrusion TP"), it detects that the unevenness of the coating surface PB is abnormal. In this embodiment, the target protrusion TP (see Figures 5(a) and 5(b) described later) refers to a protrusion having a height of 0.1 mm or more based on the coating surface PB. In other words, a state in which a protrusion having such a height is present on the coating surface PB is considered to be a state in which the unevenness of the coating surface PB is not within the allowable range. The height of the target protrusion TP may be the height of the tip (upper end) of the target protrusion TP based on the height of the coating surface PB in the normal direction D1.

[0034] In this embodiment, when detecting the target protrusion TP on the coating surface PB, the abnormality detection unit 34 detects the size (height) of the target protrusion TP in stages. When the height of the target protrusion TP is, for example, a height H1 in a range of 0.1 mm or more and less than 1 mm (hereinafter referred to as the "restorable range") (see FIG. 5(a) described later), a recovery operation is performed to eliminate the state in which the target protrusion TP exists on the coating surface PB, so that the normal modeling process can be continued. Therefore, when the target protrusion TP having a height H1 in the restorable range exists on the coating surface PB, the modeling process can be continued without stopping, so that the unevenness of the coating surface PB can be said to be in a mild abnormal state (first abnormal state). Details of the recovery operation will be described later. On the other hand, for example, when the height of the target protrusion TP is a height H2 in a range of 1 mm or more (hereinafter referred to as the non-restorable range) (see FIG. 5(b) described later), it is highly likely that the modeling object M is largely deformed overall. In this case, the modeling process cannot be continued in a normal state. Therefore, when a target protrusion TP having a height H2 in the non-restorable range is present on the coating surface PB, the unevenness of the coating surface PB can be said to be a severe abnormal state (second abnormal state) in which the modeling process should be abnormally stopped.

[0035] Therefore, when the abnormality detection unit 34 detects a target protrusion TP having a height H1 in the restorable range, the abnormality detection unit 34 outputs a first abnormality detection signal S1 (see FIG. 3 described later) indicating that the unevenness of the coating surface PB is in a mild abnormal state to the control unit 50. On the other hand, when the abnormality detection unit 34 detects a target protrusion TP having a height H2 in the non-restorable range, the abnormality detection unit 34 outputs a second abnormality detection signal S2 (see FIG. 3 described later) indicating that the unevenness of the coating surface PB is in a severe abnormal state to the control unit 50. Note that, when the target protrusion TP does not exist on the coating surface PB (i.e., when a protrusion having a height of less than 0.1 mm exists on the coating surface PB, or when no protrusion exists on the coating surface PB), normal modeling processing can be continued without performing a restoration operation, so that it can be said that the unevenness of the coating surface PB is within the allowable range, that is, there is no abnormality in the unevenness of the coating surface PB. In this case, the abnormality detection unit 34 does not detect an abnormality in the unevenness of the coating surface PB. Therefore, the unevenness of the coated surface PB being within the allowable range means that the height of the protrusions that may exist on the coated surface PB is within a certain range (e.g., less than 0.1 mm) that allows the continuation of the normal modeling process. The continuation of the normal modeling process here means a state in which the normal modeling process can be continued without performing a recovery operation. Therefore, the unevenness of the coated surface PB being within the allowable range means a state in which the height of the protrusions that may exist on the coated surface PB is not within the recoverable range or the non-recoverable range. The unevenness of the coated surface PB not being within the allowable range means that the height of the protrusions that may exist on the coated surface PB is within a range that does not allow the continuation of the normal modeling process (e.g., less than 0.1 mm). The range that does not allow the continuation of the normal modeling process means both the recoverable range in which the normal modeling process cannot be continued without performing a recovery operation and the non-recoverable range in which the normal modeling process cannot be continued even if a recovery operation is performed. Therefore, the unevenness of the coated surface PB not being within the allowable range means a state in which the height of the protrusions that may exist on the coated surface PB is within the recoverable range or the non-recoverable range.

[0036] As shown in FIG. 2, the heating unit 32, the irradiation unit 33, the abnormality detection unit 34, and the supply unit 35 are arranged in this order above the main surface 6a of the table 6 along the rotation direction D21 (counterclockwise direction in FIG. 2). With the heating unit 32, the irradiation unit 33, the abnormality detection unit 34, and the supply unit 35 arranged in the rotation direction D21 in this manner, the table 6 rotates in the rotation direction D21, whereby the preheating process by the heating unit 32, the modeling process by the irradiation unit 33, the abnormality detection process by the abnormality detection unit 34, and the supply process by the supply unit 35 are performed in parallel. Each process is repeatedly performed according to the rotation of the table 6, and a modeled object M is modeled on the main surface 6a. When each process is performed in parallel in this manner, there is an advantage that the modeling time of the modeled object M can be shortened compared to when each process is performed sequentially.

[0037] The control unit 50 shown in FIG. 1 is an electronic control unit that controls the entire three-dimensional printing apparatus 1. The control unit 50 is a computer including hardware such as a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM), and software such as a program stored in the ROM. The form and location of the control unit 50 are not particularly limited. The control unit 50 may be electrically connected to the driving unit 10 and the modeling processing unit 30. As shown in FIG. 3, the control unit 50 includes, as functional components, an operation control unit 51 that controls the operations of the driving unit 10 and the modeling processing unit 30, and an operation selection unit 52 that selects the control content of the operation control unit 51. These functional components are realized by the CPU executing a program.

[0038] The operation control unit 51 performs rotation control to rotate the table 6. For example, the operation control unit 51 sets the rotation speed of the table 6. The operation control unit 51 outputs a control signal for controlling the rotation of the table 6 to the rotation unit 11, and the rotation unit 11 operates according to the control signal. As a result, the table 6 rotates in a rotation direction D21 at a constant rotation speed, for example.

[0039] The operation control unit 51 performs lifting control to lift and lower the table 6. For example, the operation control unit 51 sets the descent speed of the table 6. The operation control unit 51 outputs a control signal for controlling the lifting and lowering of the table 6 to the lifting unit 12, and the lifting unit 12 operates in accordance with the control signal. As a result, the table 6 descends, for example, at a constant descent speed. The descent speed of the table 6 may be determined according to the rotation speed of the table 6, for example.

[0040] The operation control unit 51 performs supply control to supply the powder P onto the main surface 6a of the table 6. For example, the operation control unit 51 sets the timing of supplying the powder P onto the main surface 6a, the supply amount of the powder P, and the operation of the powder application mechanism. The operation control unit 51 outputs a control signal for supply control to the supply unit 35, and the supply unit 35 operates in accordance with the control signal. As a result, the powder P on the main surface 6a of the table 6 is spread evenly as the table 6 rotates, and a powder bed PA is formed on the main surface 6a.

[0041] The operation control unit 51 performs preheating control to preheat the powder bed PA formed on the main surface 6a of the table 6. For example, the operation control unit 51 sets the amount of heat to be applied to the powder bed PA. The amount of heat to be applied to the powder bed PA may be determined according to the material and type of the powder P, the rotation speed of the table 6, and the like. The operation control unit 51 outputs a control signal for performing preheating control to the heating unit 32, and the heating unit 32 operates according to the control signal. As a result, the powder bed PA on the main surface 6a is preheated at the position of the heating unit 32.

[0042] The operation control unit 51 controls the irradiation of the electron beam when the powder P of the powder bed PA is melted or sintered. For example, the operation control unit 51 sets the timing to start the irradiation of the electron beam, the timing to end the irradiation of the electron beam, and the irradiation position of the electron beam. The irradiation position of the electron beam is set in a region of the coating surface PB of the powder bed PA where the molded object M is to be molded. Three-dimensional CAD (Computer Aided Design) data of the molded object M is input to the operation control unit 51. The operation control unit 51 generates two-dimensional slice data based on this three-dimensional CAD data. The slice data is, for example, data of a horizontal cross section of the molded object M, and is a collection of a large number of data according to the vertical positions. The operation control unit 51 sets the irradiation position of the electron beam based on this slice data. The operation control unit 51 outputs a control signal for performing irradiation control to the irradiation unit 33, and the irradiation unit 33 operates according to the control signal. As a result, the preheated powder P melts at the irradiation position of the electron beam and then solidifies. The molded object M is formed by the solidification of the powder P.

[0043] The operation control unit 51 controls the abnormality detection of the abnormality detection unit 34 when detecting an abnormality in the unevenness of the coating surface PB. For example, the operation control unit 51 sets the timing for starting detection by the abnormality detection unit 34 and the timing for ending detection by the abnormality detection unit 34. The operation control unit 51 outputs a control signal for performing the abnormality detection control to the abnormality detection unit 34, and the abnormality detection unit 34 operates in accordance with the control signal. In this manner, the operation control unit 51 executes a series of molding processes for forming the molded object M by performing rotation control, elevation control, preheating control, irradiation control, abnormality detection control, and supply control of the table 6.

[0044] The operation selection unit 52 selects the control contents of the operation control unit 51 according to the detection result by the abnormality detection unit 34. When the abnormality detection unit 34 detects that there is an abnormality in the unevenness of the coating surface PB, it outputs a first abnormality detection signal S1 or a second abnormality detection signal S2 to the operation selection unit 52. The operation selection unit 52 judges the abnormal state of the unevenness of the coating surface PB according to the output of the first abnormality detection signal S1 or the second abnormality detection signal S2. Then, the operation control unit 51 outputs an instruction signal S3 instructing the control contents of the operation control unit 51 to the operation control unit 51 according to the judgment result. The operation control unit 51 performs operation control according to the instruction signal S3. The control contents of the operation control unit 51 include a normal operation, a recovery operation, and an abnormality stop operation. The normal operation is an operation for performing a normal modeling process including a supply process, a preheating process, and an irradiation process. The recovery operation is an operation for recovering from a state in which there is an abnormality in the unevenness of the coating surface PB to a state in which there is no abnormality. The abnormality stop operation is an operation for abnormally stopping the modeling process.

[0045] When the operation selection unit 52 has not received either the first abnormality detection signal S1 or the second abnormality detection signal S2 from the abnormality detection unit 34, that is, when it is determined that there is no abnormality in the uneven state of the application surface PB, the operation selection unit 52 selects the normal operation as the control content of the operation control unit 51. In this case, the operation control unit 51 controls the drive unit 10 and the formation processing unit 30 to continue the normal formation processing. When the operation selection unit 52 receives the first abnormality detection signal S1 from the abnormality detection unit 34, that is, when it is determined that the unevenness of the application surface PB is in a mildly abnormal state, the operation selection unit 52 selects the restoration operation as the control content of the operation control unit 51. In this case, the control content of the operation control unit 51 switches from the normal operation to the restoration operation. Then, the operation control unit 51 controls the drive unit 10 and the formation processing unit 30 so as to restore the unevenness of the application surface PB to a state without abnormalities.

[0046] The recovery operation is an operation in which a series of modeling processes using preheating control, irradiation control, and supply control are repeatedly performed in a state in which the modeling conditions at the location where the abnormality occurred on the coating surface PB (i.e., the location of the target protrusion TP) are changed. Examples of changes in the modeling conditions include changes in the scanning speed of the irradiation unit 33 and changes in the current value of the electron beam. By changing the modeling conditions in this way, the formation speed of the target protrusion TP is slowed down relatively to the formation speed of the layers of the surrounding object M. When a series of modeling processes are performed in this state, the height of the target protrusion TP relative to the coating surface PB becomes relatively lower as the modeling process progresses.

[0047] As a result, the target protrusion TP gradually becomes lower relative to the coating surface PB, so that the target protrusion TP can be embedded in the coating surface PB. In other words, the restoration operation is an operation for embedding the target protrusion TP in the coating surface PB. In this way, the state in which the target protrusion TP exists on the coating surface PB is resolved. In other words, the unevenness of the coating surface PB is restored to a normal state. After restoring the unevenness of the coating surface PB to a normal state, the operation selection unit 52 selects the normal operation. Therefore, after completing the restoration operation, the operation control unit 51 performs the normal operation again.

[0048] On the other hand, when the operation selection unit 52 receives the second abnormality detection signal S2 from the abnormality detection unit 34, that is, when it is determined that the unevenness of the application surface PB is in a severe abnormal state, the operation selection unit 52 selects the abnormality stop operation as the control content of the operation control unit 51. In this case, the control content of the operation control unit 51 switches from the normal operation to the abnormality stop operation. Then, the operation control unit 51 forcibly stops the operations of the drive unit 10 and the formation processing unit 30, and forcibly stops a series of formation processes.

[0049] Here, the details of the configuration of the abnormality detection unit 34 will be described. As shown in FIG. 2, the abnormality detection unit 34 is arranged so as to extend along the radial direction with respect to the rotation axis C. The abnormality detection unit 34 is arranged between the supply unit 35 and the irradiation unit 33 in the circumferential direction D2. The abnormality detection unit 34 is arranged, for example, at a position adjacent to the supply unit 35 in the opposite direction of the rotation direction D21. The abnormality detection unit 34 may be fixed to the supply unit 35 in the opposite direction. The opposite direction of the rotation direction D21 coincides with the scanning direction (movement direction) of the abnormality detection unit 34 with respect to the table 6. Therefore, hereinafter, the opposite direction of the rotation direction D21 will be described as the scanning direction D22. The abnormality detection unit 34 has a plurality of abnormality detection units 40 for detecting abnormalities in the uneven state of the coating surface PB. Each abnormality detection unit 40 is linearly arranged along the radial direction. Therefore, each abnormality detection unit 40 is arranged at a different position from each other in the radial direction. Each abnormality detection unit 40 may be fixed to each other in the radial direction. The anomaly detection units 40 have, for example, the same configuration as each other.

[0050] Fig. 4 shows a cross section of the anomaly detection unit 40 when cut along a plane along the normal direction D1 and the circumferential direction D2. As shown in Fig. 4, the anomaly detection unit 40 includes an insulator 41 (support), a first detection plate 42A (first conductor), a second detection plate 42B (second conductor), a third detection plate 42C (third conductor), a continuity detection section 43, and an anomaly determination section 44. Hereinafter, when the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C are not to be distinguished from one another, they will be collectively referred to simply as "detection plate 42".

[0051] The insulator 41 is a block-shaped member having electrical insulation properties. The insulator 41 is fixed at a position spaced above the application surface PB with a predetermined distance therebetween. The insulator 41 is fixed, for example, to the supply unit 35 (see FIG. 2) adjacent to the circumferential direction D2. Therefore, when the table 6 rotates in the rotation direction D21, the insulator 41 rotates (moves) relatively to the table 6 together with the supply unit 35 in the scanning direction D22. The lower surface 41a of the insulator 41 faces the application surface PB in the normal direction D1. The lower surface 41a of the insulator 41 functions as a support surface for supporting the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C.

[0052] The lower surface 41a of the insulator 41 includes a pair of first support grooves 41b for supporting the first detection plate 42A, a pair of second support grooves 41c for supporting the second detection plate 42B, and a pair of third support grooves 41d for supporting the third detection plate 42C. The pair of first support grooves 41b are arranged on the lower surface 41a of the insulator 41 at a distance from each other in the scanning direction D22, and extend linearly along the radial direction. The pair of second support grooves 41c are arranged on the outside of the pair of first support grooves 41b in the scanning direction D22, and extend linearly along the radial direction. The pair of third support grooves 41d are arranged on the outside of the pair of second support grooves 41c in the scanning direction D22, and extend linearly along the radial direction. The interval between the first support groove 41b and the second support groove 41c in the scanning direction D22 is set to be the same as the interval between the second support groove 41c and the third support groove 41d in the scanning direction D22.

[0053] The detection plate 42 is a conductive plate for detecting the target protrusion TP (i.e., irregularities in the coating surface PB) and is configured to be elastically deformable. Therefore, the detection plate 42 is formed of a material that is conductive and elastically deformable. For example, the detection plate 42 may be formed of a material having a higher elastic coefficient than the shaped object M. The detection plate 42 is disposed between the lower surface 41a of the insulator 41 in the normal direction D1 and the coating surface PB, so that the normal direction D1 is the thickness direction, and is curved to be convex downward. The state in which the detection plate 42 is disposed so that the normal direction D1 is the thickness direction means a state in which the detection plate 42 is disposed so that the thickness direction of the detection plate 42 is along the normal direction D1. In this state, the main surface of the detection plate 42 that is perpendicular to the thickness direction is disposed so that it faces the coating surface PB in the normal direction D1. In other words, the detection plate 42 is disposed so that the extension direction of the detection plate 42 is along the surface direction. The detection plate 42 is supported by the lower surface 41a of the insulator 41. Therefore, when the table 6 rotates in the rotation direction D21, the detection plate 42 rotates (moves) together with the insulator 41 in the scanning direction D22 relative to the table 6. Since the detection plate 42 is supported by the insulator 41, the distance between the coating surface PB and the detection plate 42 in the normal direction D1 is maintained constant.

[0054] The first detection plate 42A, the second detection plate 42B, and the third detection plate 42C are arranged in this order from the lower surface 41a of the insulator 41 toward the coating surface PB in the normal direction D1. Therefore, the first detection plate 42A faces the coating surface PB in the normal direction D1 via the second detection plate 42B and the third detection plate 42C. The first detection plate 42A is supported by a pair of first support grooves 41b in a state in which it is curved so as to be convex from the lower surface 41a of the insulator 41 toward the coating surface PB in the normal direction D1. Specifically, both ends 42a of the first detection plate 42A in the scanning direction D22 are fitted into the pair of first support grooves 41b without any gaps. As a result, both ends 42a of the first detection plate 42A are supported and fixed by the pair of first support grooves 41b. The portion between both ends 42a of the first detection plate 42A forms a curved portion 42b that is curved so as to be convex from both ends 42a toward the coating surface PB in the normal direction D1.

[0055] As shown in FIG. 4, the cross-sectional shape of the curved portion 42b of the first detection plate 42A is arc-shaped so as to be convex from both ends 42a of the first detection plate 42A toward the application surface PB. The term "arc-shaped" means a shape curved like a bow, and includes, for example, a circular arc, a parabola, a C-shape, and a U-shape. The curved portion 42b may be formed only in a part of the first detection plate 42A. Since the first detection plate 42A is made of an elastically deformable material, the curved portion 42b is elastically deformable in the normal direction D1. Therefore, when the curved portion 42b is pressed from below, a reaction force acts upward, and the curved portion 42b is displaced upward by elastic deformation. The first detection plate 42A may be made of a rigid body that does not elastically deform. In this case, the curved portion 42b is not displaced even when pressed from below.

[0056] The second detection plate 42B is disposed between the first detection plate 42A and the coating surface PB in the normal direction D1. The second detection plate 42B is supported by the pair of second support grooves 41c in a state where it is curved so as to be convex from the lower surface 41a of the insulator 41 toward the coating surface PB in the normal direction D1. Specifically, both ends 42c of the second detection plate 42B in the scanning direction D22 are fitted into the pair of second support grooves 41c without any gaps. As a result, both ends 42c of the second detection plate 42B are supported and fixed by the pair of second support grooves 41c. The portion between both ends 42c of the second detection plate 42B is a curved portion 42d that is curved so as to be convex from both ends 42c toward the coating surface PB in the normal direction D1.

[0057] As shown in FIG. 4, the cross-sectional shape of the curved portion 42d of the second detection plate 42B is arc-shaped so as to be convex from both ends 42c of the second detection plate 42B toward the application surface PB. The curved portion 42d may be formed only in a part of the second detection plate 42B. For example, the curved portion 42d is curved so as to follow the curved portion 42b of the first detection plate 42A, and is spaced apart from the curved portion 42b of the first detection plate 42A at a constant interval. The state in which the curved portion 42d is spaced apart from the curved portion 42b at a constant interval means a state in which the distance between the curved portion 42d and the curved portion 42b in the normal direction D1 is maintained constant at each position along the scanning direction D22. Since the second detection plate 42B is made of an elastically deformable material, the curved portion 42d is elastically deformable in the normal direction D1. Therefore, when curved portion 42d is pressed from below, a reaction force acts upward and curved portion 42d is displaced upward by elastic deformation, so that curved portion 42d is displaced upward from a position separated from curved portion 42b to a position in contact with curved portion 42b.

[0058] The third detection plate 42C is disposed between the second detection plate 42B and the coating surface PB in the normal direction D1. The third detection plate 42C is supported by the pair of third support grooves 41d in a state where it is curved so as to be convex from the lower surface 41a of the insulator 41 toward the coating surface PB in the normal direction D1. Specifically, both ends of the third detection plate 42C in the scanning direction D22 are fitted into the pair of third support grooves 41d without any gaps. As a result, both ends 42e of the third detection plate 42C are supported and fixed by the pair of third support grooves 41d. The portion between both ends 42e of the third detection plate 42C is a curved portion 42f that is curved so as to be convex from both ends 42e toward the coating surface PB in the normal direction D1.

[0059] As shown in FIG. 4, the cross-sectional shape of the curved portion 42f of the third detection plate 42C is arc-shaped so as to be convex from both ends 42e of the third detection plate 42C toward the application surface PB. The curved portion 42f may be formed only in a part of the third detection plate 42C. For example, the curved portion 42f is curved so as to follow the curved portion 42d of the second detection plate 42B, and is spaced apart from the curved portion 42d at a constant interval. The state in which the curved portion 42f is spaced apart from the curved portion 42d at a constant interval means that the distance between the curved portion 42f and the curved portion 42d in the normal direction D1 is maintained constant at each position along the scanning direction D22. A distance d2 between the curved portion 42f of the third detection plate 42C and the curved portion 42d of the second detection plate 42B is set, for example, to be the same as a distance d3 between the curved portion 42d of the second detection plate 42B and the curved portion 42b of the first detection plate 42A.

[0060] Therefore, the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C are arranged so as to be spaced apart at equal intervals vertically. The third detection plate 42C is spaced apart from the application surface PB at a predetermined interval d1 upward. Since the third detection plate 42C is made of an elastically deformable material, the curved portion 42f of the third detection plate 42C is elastically deformable in the normal direction D1. Therefore, when the curved portion 42f is pressed from below, a reaction force acts upward, and the curved portion 42f is displaced upward by elastic deformation. As a result, the curved portion 42f of the third detection plate 42C is displaced upward from a position spaced apart from the curved portion 42d of the second detection plate 42B to a position in contact with the curved portion 42d of the second detection plate 42B.

[0061] The distance d1 between the third detection plate 42C and the application surface PB, the distance d2 between the second detection plate 42B and the third detection plate 42C, and the distance d3 between the first detection plate 42A and the second detection plate 42B are set according to the height of the target protrusion TP. For example, the distances d1, d2, and d3 are set to be the same as each other. The sum of the distances d2 and d3 is set to the lower limit value (for example, 0.1 mm) of the height H1 of the target protrusion TP in the restorable range. Therefore, as shown in FIG. 5(a), when the abnormality detection unit 40 passes through the target protrusion TP of the height H1 of the restorable range, the curved portion 42f of the third detection plate 42C collides with the target protrusion TP and is pressed upward, so that it is displaced upward while being elastically deformed. As a result, the third detection plate 42C is in contact with the second detection plate 42B. Meanwhile, the second detection plate 42B and the first detection plate 42A are maintained in a spaced state.

[0062] The sum of the intervals d1, d2, and d3 is set to the lower limit (for example, 1 mm) of the height of the target protrusion TP of the height H2 of the non-restorable range. Therefore, as shown in FIG. 5(b), when the abnormality detection unit 40 passes the target protrusion TP of the non-restorable range, the curved portion 42f of the third detection plate 42C collides with the target protrusion TP and is pressed upward, so that it is displaced upward while elastically deforming. Then, the curved portion 42f of the third detection plate 42C contacts the curved portion 42d of the second detection plate 42B and presses the curved portion 42d further upward. The curved portion 42d of the second detection plate 42B pressed upward is displaced upward while elastically deforming, and contacts the curved portion 42b of the first detection plate 42A. As a result, the third detection plate 42C, the second detection plate 42B, and the first detection plate 42A are in contact with each other. Note that the intervals d1, d2, and d3 do not have to be set to be the same as each other. For example, the interval d2 may be set to be smaller than the interval d3, or the interval d3 may be set to be smaller than the interval d2.

[0063] Referring again to FIG. 4, the continuity detection unit 43 detects the continuity between the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C. The continuity detection unit 43 includes a first continuity detection circuit 46 and a second continuity detection circuit 47. The first continuity detection circuit 46 is electrically connected to one end 42c of the second detection plate 42B and one end 42e of the third detection plate 42C. The first continuity detection circuit 46 includes a power source 46a that applies a voltage to the second detection plate 42B and the third detection plate 42C, and a detection sensor 46b that detects the continuity between the second detection plate 42B and the third detection plate 42C. The detection sensor 46b detects the continuity between the third detection plate 42C and the second detection plate 42B, for example, in response to a change in the electrical resistance between the third detection plate 42C and the second detection plate 42B. In this case, the detection sensor 46b uses an ammeter to measure the value of the current flowing through the third detection plate 42C and the second detection plate 42B, and uses a voltmeter to measure the value of the voltage applied to the third detection plate 42C and the second detection plate 42B. Then, the detection sensor 46b calculates the electrical resistance value based on the measured current value and voltage value, and monitors the change in the calculated electrical resistance value.

[0064] As shown in FIG. 4, when the third detection plate 42C is separated from the second detection plate 42B, no current flows between the third detection plate 42C and the second detection plate 42B, and the electrical resistance between the third detection plate 42C and the second detection plate 42B is infinite. In this case, the detection sensor 46b does not detect the electrical continuity between the third detection plate 42C and the second detection plate 42B, since the electrical resistance between the third detection plate 42C and the second detection plate 42B does not change from infinity. On the other hand, as shown in FIG. 5(a), when the third detection plate 42C comes into contact with the second detection plate 42B and a current flows between the third detection plate 42C and the second detection plate 42B, the electrical resistance between the third detection plate 42C and the second detection plate 42B changes (decreases). In this case, the detection sensor 46b detects the electrical continuity between the third detection plate 42C and the second detection plate 42B in response to the electrical resistance decreasing from infinity. Then, the detection sensor 46b outputs to the abnormality determination unit 44 a first continuity detection signal S4 indicating that continuity has been established between the third detection plate 42C and the second detection plate 42B.

[0065] As shown in FIG. 4, the second continuity detection circuit 47 is electrically connected to one end 42a of the first detection plate 42A and one end 42c of the second detection plate 42B. The second continuity detection circuit 47 includes a power source 47a that applies a voltage to the first detection plate 42A and the second detection plate 42B, and a detection sensor 47b that detects the continuity between the first detection plate 42A and the second detection plate 42B. The detection sensor 47b detects the continuity between the second detection plate 42B and the first detection plate 42A, for example, according to a change in the electrical resistance value between the second detection plate 42B and the first detection plate 42A. In this case, the detection sensor 47b measures the current value flowing between the second detection plate 42B and the first detection plate 42A with an ammeter, and measures the voltage value applied to the second detection plate 42B and the first detection plate 42A with a voltmeter. Then, the detection sensor 47b calculates an electric resistance value based on the measured current value and voltage value, and monitors a change in the calculated electric resistance value.

[0066] As shown in Fig. 4 and Fig. 5(a), when the second detection plate 42B is separated from the first detection plate 42A, no current flows between the second detection plate 42B and the first detection plate 42A, and the electrical resistance between the second detection plate 42B and the first detection plate 42A is infinite. In this case, the detection sensor 47b does not detect the electrical continuity between the second detection plate 42B and the first detection plate 42A, because the electrical resistance between the second detection plate 42B and the first detection plate 42A does not change from infinity. On the other hand, as shown in Fig. 5(b), when the second detection plate 42B comes into contact with the first detection plate 42A and a current flows between the second detection plate 42B and the first detection plate 42A, the electrical resistance between the second detection plate 42B and the first detection plate 42A changes (decreases). In this case, the detection sensor 47b detects the electrical continuity between the second detection plate 42B and the first detection plate 42A in response to the electrical resistance value decreasing from infinity. Then, the detection sensor 47b outputs to the abnormality determination unit 44 a second continuity detection signal S5 indicating that the second detection plate 42B and the first detection plate 42A are electrically connected to each other.

[0067] The abnormality determination unit 44 determines whether or not there is an abnormality in the unevenness of the coating surface PB, and the degree of the abnormal state of the unevenness of the coating surface PB, according to the detection result of the continuity detection unit 43. When neither the first continuity detection signal S4 nor the second continuity detection signal S5 is received, the abnormality determination unit 44 determines that the unevenness of the coating surface PB is within the allowable range and determines that there is no abnormality in the unevenness of the coating surface PB. On the other hand, when the abnormality determination unit 44 receives the first continuity detection signal S4, or both the first continuity detection signal S4 and the second continuity detection signal S5, it determines that the unevenness of the coating surface PB is not within the allowable range and determines that there is an abnormality in the unevenness of the coating surface PB. In this case, the abnormality determination unit 44 further determines the abnormal state of the unevenness of the coating surface PB, that is, the degree of the size of the target protrusion TP of the coating surface PB.

[0068] When the abnormality determination unit 44 receives only the first continuity detection signal S4, that is, when only the third detection plate 42C and the second detection plate 42B are conductive (see FIG. 5(a)), it determines that the target protrusion TP of the height H1 of the recovery range is present on the coating surface PB. In this case, the abnormality determination unit 44 outputs the first abnormality detection signal S1 indicating that the unevenness of the coating surface PB is in a mild abnormal state to the operation selection unit 52 of the control unit 50. On the other hand, when the abnormality determination unit 44 receives both the first continuity detection signal S4 and the second continuity detection signal S5, that is, when the third detection plate 42C, the second detection plate 42B, and the first detection plate 42A are all conductive (see FIG. 5(b)), it determines that the target protrusion TP of the height H2 of the non-recoverable range is present on the coating surface PB. In this case, the abnormality determination unit 44 outputs the second abnormality detection signal S2 indicating that the unevenness of the coating surface PB is in a severe abnormal state to the operation selection unit 52 of the control unit 50. The abnormality determination section 44 may be provided in the control section 50 instead of in the abnormality detection section 34. In this case, the first continuity detection signal S4 and the second continuity detection signal S5 from the continuity detection section 43 are output to the control section 50, and the abnormality determination section 44 of the control section 50 determines whether there is an abnormality in the unevenness of the coating surface PB.

[0069] Next, the operation performed by the control unit 50 when forming one layer of the model M will be described with reference to FIG.

[0070] The control unit 50 executes a normal modeling process while rotating the table 6 in the rotation direction D21. At this time, the operation selection unit 52 selects the normal operation. The operation control unit 51 forms a powder bed PA on the table 6 by supplying the powder P, and then causes the heating unit 32 to execute a preheating process of the powder P (step S11). Thereafter, the powder P enters a region below the irradiation unit 33 while moving in the rotation direction D21 with the rotation of the table 6. Next, the operation control unit 51 causes the irradiation unit 33 to execute a modeling process of the powder P (step S12). Specifically, the operation control unit 51 causes the powder P present within the irradiation range of the irradiation unit 33 to be irradiated with an electron beam, thereby solidifying the powder P irradiated with the electron beam. The solidified powder P approaches the anomaly detection unit 34 while moving with the rotation of the table 6.

[0071] Next, the operation control unit 51 causes the abnormality detection unit 34 to execute an abnormality detection process. That is, the operation control unit 51 causes the abnormality detection unit 34 to detect whether there is an abnormality in the unevenness of the coating surface PB of the powder bed PA (step S13). Specifically, each abnormality detection unit 40 of the abnormality detection unit 34 detects whether any of the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C is conductive while rotating (moving) relatively to the coating surface PB in the scanning direction D22. If the target protrusion TP does not exist on the coating surface PB, none of the abnormality detection units 40 outputs the first abnormality detection signal S1 and the second abnormality detection signal S2 to the operation selection unit 52. In this case, the operation selection unit 52 determines that there is no abnormality in the unevenness of the coating surface PB (Yes in step S13), and continues to select the normal operation. Then, the operation control unit 51 executes the supply process on the coating surface PB determined to be abnormal. That is, the operation control unit 51 controls the supply unit 35 to perform a coating operation of spreading the coating surface PB evenly after supplying the powder P to the coating surface PB (step S14). In this manner, the operation control unit 51 performs a normal operation while the table 6 rotates once, whereby a series of modeling processes for forming one layer of the modeled object M is normally completed.

[0072] On the other hand, when the target protrusion TP exists on the coating surface PB, any one of the abnormality detection units 40 outputs the first abnormality detection signal S1 or the second abnormality detection signal S2 to the operation selection unit 52. In this case, the operation selection unit 52 judges that there is an abnormality in the unevenness of the coating surface PB (No in step S13), and then judges whether the abnormality in the unevenness of the coating surface PB can be restored (step S15). When the target protrusion TP of the height H1 of the restorable range exists on the coating surface PB, the third detection plate 42C is pushed upward and contacts the second detection plate 42B, and only the third detection plate 42C and the second detection plate 42B are conductive. In this case, any one of the abnormality detection units 40 outputs the first abnormality detection signal S1 to the operation selection unit 52. Then, the operation selection unit 52 judges that the abnormality in the unevenness of the coating surface PB can be restored (Yes in step S15), and switches the control content from the normal operation to the restoration operation. In response to this, the operation control unit 51 interrupts the normal operation and executes a recovery operation.

[0073] Here, the detailed operation of the recovery operation will be described with further reference to FIG. 7. When performing the recovery operation, the operation control unit 51 first identifies the abnormality occurrence location on the application surface PB (i.e., the position of the target protrusion TP present on the application surface PB). Specifically, the operation control unit 51 first determines the position of the abnormality occurrence location in the circumferential direction D2 (step S21). For example, the operation control unit 51 identifies the angular position (i.e., the position in the circumferential direction D2) of the abnormality detection unit 34 that output the first abnormality detection signal S1 around the rotation axis C, and determines the identified angular position as the position of the abnormality occurrence location in the circumferential direction D2. Next, the operation control unit 51 determines the radial position of the abnormality occurrence location (step S22). The abnormality detection unit 34 is composed of a plurality of abnormality detection units 40 separated in the radial direction. Therefore, the operation control unit 51 identifies the abnormality detection unit 40 that output the first abnormality detection signal S1 among the plurality of abnormality detection units 40, and determines the position of the identified abnormality detection unit 40 as the radial position of the abnormality occurrence location.

[0074] In this way, the operation control unit 51 determines the position of the abnormality occurrence location on the coating surface PB. At this time, the operation control unit 51 can also calculate the range of the abnormality occurrence location in the scanning direction D22, that is, the width of the target protrusion TP in the scanning direction D22. When the abnormality detection unit 40 passes over the target protrusion TP on the coating surface PB in the scanning direction D22, the third detection plate 42C contacts the second detection plate 42B at the location where the target protrusion TP exists, and the third detection plate 42C and the second detection plate 42B are in a conductive state, and at the location where the target protrusion TP does not exist, the third detection plate 42C separates from the second detection plate 42B, and the third detection plate 42C and the second detection plate 42B are not in a conductive state. Therefore, the third detection plate 42C and the second detection plate 42B are in a conductive state only while the abnormality detection unit 40 passes over the target protrusion TP. Therefore, the operation control unit 51 can grasp the width of the target protrusion TP in the scanning direction D22 from the time during which the third detection plate 42C and the second detection plate 42B are in electrical conduction. Specifically, the operation control unit 51 can calculate the width of the target protrusion TP in the scanning direction D22 from the movement speed of the anomaly detection unit 40 in the scanning direction and the time during which the third detection plate 42C and the second detection plate 42B are in electrical conduction.

[0075] Next, the operation control unit 51 changes the modeling conditions of the determined abnormality occurrence location (step S23). Specifically, the operation control unit 51 changes the irradiation conditions of the electron beam for the abnormality occurrence location, i.e., the target protrusion TP present on the coating surface PB. In this state, the operation control unit 51 repeatedly executes a series of modeling processes by preheating control, irradiation control, and supply control to eliminate the state in which the target protrusion TP exists on the coating surface PB, i.e., the state in which the coating surface PB has an abnormality. After that, when the operation control unit 51 ends the recovery operation, the operation selection unit 52 switches the control content from the recovery operation to the normal operation. In response to this, the operation control unit 51 executes the remaining operation of the interrupted normal operation. That is, as shown in FIG. 6, the operation control unit 51 causes the supply unit 35 to execute the remaining application operation (step S14) and normally ends the series of processes.

[0076] On the other hand, when a target protrusion TP with a height H2 in the non-restorable range is present on the coating surface PB, the third detection plate 42C is pushed upward together with the second detection plate 42B, the second specimen plate comes into contact with the first detection plate 42A, and the third detection plate 42C, the second detection plate 42B, and the first detection plate 42A are all electrically connected. Therefore, one of the anomaly detection units 40 outputs a second anomaly detection signal S2 to the operation selection unit 52. In this case, the operation selection unit 52 determines that the irregularity of the coating surface PB is non-restorable (No in step S15), and switches the control content from normal operation to an abnormality stop operation. In response to this, the operation control unit 51 forcibly stops the operation of the drive unit 10 and the forming processing unit 30, and terminates the operation due to an abnormality.

[0077] <Effects> The effects obtained by the three-dimensional modeling apparatus 1 and the abnormality detection unit 34 according to the present embodiment described above will be described. In this embodiment, the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C are arranged in a line in the normal direction D1, and the second detection plate 42B and the third detection plate 42C are displaced in the normal direction D1 to detect an abnormality in the unevenness of the coating surface PB. In this embodiment, all the detection plates 42 are arranged so that the normal direction D1 is the thickness direction, and are curved so as to be convex downward. When the detection plates 42 are arranged in this manner, the influence of the dimensional change of the detection plate 42 due to thermal expansion on the abnormality detection accuracy of the unevenness of the coating surface PB can be reduced compared to the case where the detection plates are arranged in a line in the scanning direction D22 so as to stand upright with respect to the coating surface PB.

[0078] FIG. 8(a) shows a case where the detection plate 142 is supported by the insulator 141 so as to stand on the application surface PB. In this way, when the detection plate 142 is arranged to extend in the normal direction D1, if the dimension of the detection plate 142 in the normal direction D1 before thermal expansion is L and the dimensional change of the detection plate 42 due to thermal expansion is ΔL, the dimension of the detection plate 142 in the normal direction D1 after thermal expansion is expressed as (L+ΔL). On the other hand, as shown in FIG. 8(b), in this embodiment, the detection plate 42 is arranged so that the normal direction D1 is the thickness direction, and is curved so as to be convex downward. In the example shown in FIG. 8(b), for the sake of simplicity of explanation, a case where the detection plate 42 is curved in a semicircular arc is shown. In this case, the dimension of detection plate 42 before thermal expansion is L, which is the same as the dimension of detection plate 142, the dimensional change of detection plate 42 due to thermal expansion is ΔL, the radial distance of detection plate 42 from insulator 41 before thermal expansion (hereinafter referred to as "radius") is R, and the change in radius of detection plate 42 due to thermal expansion is ΔR. In this case, when the dimension (L+ΔL) of detection plate 42 after thermal expansion is converted to the radius (R+ΔR) of detection plate 42 after expansion, the dimension (L+ΔL) can be expressed as radius (R+ΔR)×π. Furthermore, when the changes ΔL and ΔR are compared, it can be seen that the change in radius ΔR is 1 / π smaller than the dimensional change ΔL.

[0079] In this way, by arranging the detection plate 42 so that it lies flat in the surface direction (i.e. so that the detection plate 42 extends in the surface direction) rather than standing upright in the normal direction D1 relative to the coating surface PB, it is possible to prevent the position of the detection plate 42 from significantly changing in the normal direction D1 relative to the coating surface PB even if the dimensions of the detection plate 42 change due to thermal expansion. Therefore, in this embodiment, the distance between the detection plate 42 and the coating surface PB can be maintained even in a high-temperature environment. This makes it possible to accurately detect the target protrusion TP. In other words, it becomes possible to accurately detect abnormalities in the unevenness of the coating surface PB.

[0080] In this embodiment, when the continuity detection unit 43 detects continuity between any of the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C, the abnormality determination unit 44 determines that the unevenness of the application surface PB is not within the allowable range and determines that the unevenness of the application surface PB is in an abnormal state. This makes it possible to determine that the state in which the first detection plate 42A and the second detection plate 42B are in conduction as a state in which the unevenness of the application surface PB is abnormal.

[0081] In this embodiment, the second detection plate 42B is a conductive plate whose thickness direction is the normal direction D1, and has a curved portion 42d that curves toward the application surface PB in the normal direction D1. In this case, the presence of the curved portion 42d makes it easy to adjust the distance between the second detection plate 42B and the application surface PB, making it possible to detect the target protrusion TP with greater accuracy.

[0082] In this embodiment, the curved portion 42d has an arc shape that is convex toward the application surface PB in a cross section along the normal direction D1 and the scanning direction D22. In this case, when the third detection plate 42C moves relative to the application surface PB in the scanning direction D22 and collides with the target protrusion TP, the curved portion 42d of the second detection plate 42B receives a reaction force from the target protrusion TP via the third detection plate 42C and is easily displaced in the normal direction D1. As a result, when the target protrusion TP is present on the application surface PB, the first detection plate 42A can be brought into contact with the second detection plate 42B more reliably. In other words, the target protrusion TP can be detected more reliably.

[0083] In this embodiment, the curved portion 42d is configured to elastically deform from a position spaced apart from the first detection plate 42A to a position in contact with the first detection plate 42A. In this case, a configuration in which the second detection plate 42B is displaced from a position spaced apart from the first detection plate 42A to a position in contact with the first detection plate 42A can be easily realized.

[0084] In this embodiment, both end portions 42c of the second detection plate 42B are supported by the insulator 41, and the portion between both end portions 42c of the second detection plate 42B forms the curved portion 42d. In this case, it is possible to easily form the second detection plate 42B having the curved portion 42d while ensuring electrical insulation between the first detection plate 42A and the second detection plate 42B.

[0085] In this embodiment, when the third detection plate 42C comes into contact with the second detection plate 42B, the continuity detection unit 43 outputs a first continuity detection signal S4 indicating that continuity between the third detection plate 42C and the second detection plate 42B has been detected, and when the second detection plate 42B comes into contact with the first detection plate 42A, the continuity detection unit 43 outputs a second continuity detection signal S5 indicating that continuity between the second detection plate 42B and the first detection plate 42A has been detected. This makes it possible to detect the height of the target protrusion TP present on the application surface PB in stages according to the state of continuity between the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C.

[0086] In this embodiment, when the continuity detection unit 43 outputs only the first continuity detection signal S4, the abnormality determination unit 44 determines that the unevenness of the coating surface PB is in a first abnormal state, and when the continuity detection unit 43 outputs both the first continuity detection signal S4 and the second continuity detection signal S5, the abnormality determination unit 44 determines that the unevenness of the coating surface PB is in a second abnormal state different from the first abnormal state. In this configuration, when the continuity detection unit 43 outputs only the first continuity detection signal S4, it can be determined that a target protrusion TP with a height that does not reach at least the first detection plate 42A is present on the coating surface PB (first abnormal state). On the other hand, when the continuity detection unit 43 outputs both the first continuity detection signal S4 and the second continuity detection signal S5, it can be determined that a target protrusion TP that is higher than the one when the continuity detection unit 43 outputs only the first continuity detection signal S4 is present on the coating surface PB (second abnormal state). In this manner, with the above-described configuration, it is possible to detect abnormal unevenness in the coating surface PB in a stepwise manner depending on the conductive state between the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C.

[0087] In this embodiment, the third detection plate 42C is a conductive plate whose thickness direction is the normal direction D1, and has a curved portion 42f that curves toward the application surface PB in the normal direction D1. This makes it easy to adjust the distance between the third detection plate 42C and the application surface PB due to the presence of the curved portion 42f. As a result, it becomes possible to detect the target protrusion TP with higher accuracy.

[0088] In this embodiment, when the abnormality determination unit 44 determines that the unevenness of the coating surface PB is in a first abnormal state, the operation control unit 51 causes the supply unit 35 and the irradiation unit 33 to execute a recovery operation for eliminating the abnormality in the unevenness of the coating surface PB, and when the abnormality determination unit 44 determines that the unevenness of the coating surface PB is in a second abnormal state, the operation control unit 51 stops the operation of the supply unit 35 and the irradiation unit 33. In this way, by taking an appropriate response according to the abnormal state of the unevenness of the coating surface PB, the modeling process can be reliably performed in a normal state.

[0089] Although one embodiment of the present disclosure has been described above, the present invention is not limited to the above embodiment.

[0090] <Variation 1> The abnormality detection unit 40A shown in FIG. 9 is different from the abnormality detection unit 40 according to the above embodiment in that the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C are made of rigid bodies that do not elastically deform. In the abnormality detection unit 40A, the second detection plate 42B and the third detection plate 42C are supported by the insulator 41A so as to be displaceable upward. As shown in FIG. 9, a pair of second support grooves 41e and a pair of third support grooves 41f formed on the lower surface 41a of the insulator 41A extend further upward than the second support groove 41c and the third support groove 41d according to the above embodiment. In a state in which both ends 42c of the second detection plate 42B are supported by the pair of second support grooves 41e, both ends 42c of the second detection plate 42B are spaced downward from the bottom surfaces of the pair of second support grooves 41e by a predetermined distance and are also spaced from the inner side surfaces of the pair of second support grooves 41e by a predetermined distance. Similarly, in a state in which both ends 42e of the third detection plate 42C are supported by the pair of third support grooves 41f, both ends 42e of the third detection plate 42C are spaced a predetermined distance downward from the bottom surfaces of the pair of third support grooves 41f and also from the inner side surfaces of the pair of third support grooves 41f. Meanwhile, the pair of first support grooves 41b are fitted tightly into both ends 42a of the first detection plate 42A, as in the above embodiment.

[0091] In this way, the second detection plate 42B and the third detection plate 42C are configured to be movable upward relative to the application surface PB by upward displacement when pressed from below. Therefore, as shown in FIG. 10(a), when a target protrusion TP of a height H1 in the recovery range exists on the application surface PB, the third detection plate 42C collides with the target protrusion TP, receives a reaction force from the target protrusion TP, and displaces upward and contacts the second detection plate 42B. As a result, the third detection plate 42C and the second detection plate 42B are electrically connected, and the abnormality determination unit 44 transmits a first abnormality detection signal S1 to the control unit 50. On the other hand, as shown in FIG. 10(b), when a target protrusion TP of a height H2 in the non-recoverable range exists on the application surface PB, the third detection plate 42C collides with the target protrusion TP, displaces upward, and pushes the second detection plate 42B further upward while contacting the second detection plate 42B. As a result, the second detection plate 42B is also displaced upward and comes into contact with the first detection plate 42A. As a result, electrical continuity is established between the third detection plate 42C, the second detection plate 42B, and the first detection plate 42A, and the abnormality determination unit 44 transmits a second abnormality detection signal S2 to the control unit 50. Therefore, even when the abnormality detection unit 40A shown in FIG. 9 is used, the same effect as in the above embodiment can be obtained.

[0092] <Variation 2> The abnormality detection unit 40B shown in FIG. 11 has a detection rod 42D (first conductor), a detection tube 42E (second conductor), and a detection tube 42F (third conductor) instead of the first detection plate 42A, the second detection plate 42B, and the third detection plate 42C. The insulator 41B has one support groove 41g instead of the pair of first support grooves 41b, the pair of second support grooves 41c, and the pair of third support grooves 41d. The detection rod 42D is a conductive rod that extends linearly in the radial direction. The detection rod 42D is made of a rigid body that is conductive and does not elastically deform. The insulator 41B supports, for example, both ends of the detection rod 42D in the radial direction. The detection tube 42E is a cylindrical conductive tube that extends linearly in the radial direction. The detection tube 42E is made of a rigid body that is conductive and does not elastically deform. Detection tube 42E has an outer diameter larger than detection rod 42D and is disposed so as to house detection rod 42D. Insulator 41B supports, for example, both radial ends of detection tube 42E.

[0093] The detection tube 42F is a cylindrical conductive tube that extends linearly in the radial direction. The detection tube 42F is made of a rigid body that is conductive and does not elastically deform. The detection tube 42F has an outer diameter larger than that of the detection tube 42E, and is arranged to accommodate the detection tube 42E. The insulator 41B supports, for example, both ends of the detection tube 42F in the radial direction. The support groove 41g of the insulator 41B is a circular groove that extends linearly along the radial direction. The support groove 41g has an inner diameter larger than the outer diameter of the detection tube 42F, and accommodates the detection tube 42F. The width of the opening of the support groove 41g in the lower surface 41a of the insulator 41B in the scanning direction D22 is smaller than the outer diameter of the detection tube 42F. In this configuration, the downward movement of the detection tube 42F relative to the insulator 41B is restricted, while the upward movement of the detection tube 42F relative to the insulator 41B is permitted.

[0094] In this way, the detection tube 42E and the detection tube 42F are configured to be displaceable upward when pressed from below. Therefore, as shown in FIG. 12(a), when the target protrusion TP of the height H1 of the restorable range exists on the application surface PB, the detection tube 42F collides with the target protrusion TP, receives a reaction force from the target protrusion TP, displaces upward, and contacts the detection tube 42E. As a result, the detection tube 42F and the detection tube 42E are conductive, and the abnormality determination unit 44 transmits the first abnormality detection signal S1 to the control unit 50. On the other hand, as shown in FIG. 12(b), when the target protrusion TP of the height H2 of the non-restorable range exists on the application surface PB, the detection tube 42F collides with the target protrusion TP, displaces upward, and pushes the detection tube 42E further upward while contacting the detection tube 42E. As a result, the detection tube 42E is also displaced upward and contacts the detection rod 42D. As a result, the detection tube 42F, the detection tube 42E, and the detection rod 42D are all electrically connected, and the abnormality determination section 44 transmits the second abnormality detection signal S2 to the control section 50. Therefore, even when the abnormality detection unit 40B shown in Fig. 11 is used, the same effect as in the above embodiment can be obtained.

[0095] <Other Modifications> The present disclosure can be modified in various other ways. For example, the above-mentioned embodiment and each modified example may be combined with each other according to the necessary purpose and effect. In addition, the configuration of the three-dimensional printing apparatus may be appropriately modified. For example, the three-dimensional printing apparatus may form a model using an energy beam other than an electron beam. For example, the three-dimensional printing apparatus may form a model by irradiating an ion beam, a laser beam, an ultraviolet ray, or the like. In the above-mentioned embodiment, the abnormality detection unit detects the conduction between the first detection plate, the second detection plate, and the third detection plate by detecting the change in the electric resistance value of these detection plates, but may also detect the change in the current value measured by an ammeter or the change in the voltage value measured by a voltmeter. In the above-mentioned embodiment, the case where the abnormality detection unit includes the first detection plate, the second detection plate, and the third detection plate has been described, but the third detection plate may not be included. Alternatively, the abnormality detection unit may further include another detection plate between the application surface and the third detection plate. The scanning direction of the anomaly detection unit with respect to the coating surface does not have to be a circumferential direction, but may be a radial direction or another direction along the main surface of the table. [Explanation of symbols]

[0096] 1 3D printing equipment 6 Tables 6a Main surface 33 Irradiation unit 34 Anomaly detection unit (anomaly detection device) 35 Supply section 41 Insulator (support) 42A First detection plate (first conductor) 42a, 42c, 42e both ends 42B Second detection plate (second conductor) 42b, 42d, 42f Curved section 42C Third detection plate (third conductor) 42D Detection rod (first conductor) 42E Detector tube (second conductor) 42F Detector tube (third conductor) 43 Continuity detection unit 44 Abnormality determination section 50 Control section D1 Normal direction D22 Scanning direction M Modeled object P powder PA powder bed PB coating surface (surface)

Claims

1. a supply unit that supplies powder onto a main surface of the table to form a powder bed, which is a layer of the powder, on the main surface; an irradiation unit that irradiates the powder bed with an energy beam to obtain a three-dimensional model by solidifying the powder; and an abnormality detection unit that detects whether the unevenness of the surface of the powder bed irradiated with the energy beam is outside an allowable range, The abnormality detection unit is a first conductor facing the front surface in a normal direction of the main surface; a second conductor disposed between the surface and the first conductor in the normal direction, and configured to be displaced from a position spaced apart from the first conductor in the normal direction to a position in contact with the first conductor when the unevenness exceeds the allowable range by being pressed by a protrusion of the unevenness; a continuity detection unit that detects continuity between the first conductor and the second conductor when the second conductor comes into contact with the first conductor.

2. The three-dimensional printing device according to claim 1, wherein the abnormality detection unit further includes an abnormality judgment unit that judges that the unevenness of the surface of the powder bed is in an abnormal state when the conductivity detection unit detects conductivity between the first conductor and the second conductor.

3. The three-dimensional modeling apparatus according to claim 1 , wherein the second conductor is a conductive plate whose thickness direction is the normal direction and has a curved portion that is curved toward the surface in the normal direction.

4. the first conductor and the second conductor are movable relative to the surface in a scanning direction along the main surface, The three-dimensional modeling apparatus according to claim 3 , wherein the curved portion has an arc shape that is convex toward the surface in a cross section taken along the normal direction and the scanning direction.

5. The three-dimensional modeling apparatus according to claim 3 , wherein the curved portion is configured to be elastically deformed from a position spaced apart from the first conductor to a position in contact with the first conductor.

6. The insulating support member supports the first conductor and the second conductor, The three-dimensional printing apparatus according to any one of claims 3 to 5, wherein both ends of the second conductor are supported by the support body, and a portion between the both ends of the second conductor constitutes the curved portion.

7. a third conductor disposed between the surface and the second conductor in the normal direction, and configured to be displaced from a position spaced apart from the second conductor in the normal direction to a position in contact with the second conductor when the unevenness exceeds the allowable range by being pressed by a protrusion of the unevenness, The three-dimensional printing device according to any one of claims 1, 3 to 6, wherein the conduction detection unit further detects conduction between the third conductor and the second conductor when the third conductor comes into contact with the second conductor.

8. The abnormality detection unit further includes an abnormality determination unit that determines that the unevenness of the surface of the powder bed is in an abnormal state when the continuity detection unit detects continuity between any of the first conductor, the second conductor, and the third conductor, The three-dimensional printing device of claim 7, wherein the abnormality determination unit determines that the unevenness of the surface of the powder bed is in a first abnormal state when the conductivity detection unit detects conductivity between the third conductor and the second conductor, and determines that the unevenness of the surface of the powder bed is in a second abnormal state different from the first abnormal state when the conductivity detection unit detects both conductivity between the third conductor and the second conductor and conductivity between the second conductor and the first conductor.

9. The three-dimensional printing apparatus according to claim 7 or 8, wherein the third conductor is a conductive plate whose thickness direction is the normal direction and has a curved portion that is curved toward the surface in the normal direction.

10. A control unit that controls operations of the supply unit and the irradiation unit, 9. The three-dimensional printing device according to claim 8, wherein the control unit, when the abnormality determination unit determines that the surface unevenness is in the first abnormal state, causes the supply unit and the irradiation unit to execute a recovery operation to eliminate the abnormality in the surface unevenness, and, when the abnormality determination unit determines that the surface unevenness is in the second abnormal state, stops operation of the supply unit and the irradiation unit.

11. An abnormality detection device for detecting whether or not a surface unevenness of a powder bed irradiated with an energy beam on a main surface of a table is outside an allowable range, a first conductor facing the front surface in a normal direction of the main surface; a second conductor disposed between the surface and the first conductor in the normal direction, and configured to be displaced from a position spaced apart from the first conductor in the normal direction to a position in contact with the first conductor when the unevenness exceeds the allowable range by being pressed by a protrusion of the unevenness; an electrical continuity detection unit that detects electrical continuity between the first electrical conductor and the second electrical conductor when the second electrical conductor comes into contact with the first electrical conductor;

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