Additive manufacturing apparatus and powder bed forming apparatus

Abstract

To stably continue a molding process.SOLUTION: A laminate molding apparatus 1 includes a start plate 51 including a plate main surface 51a on which powder P1 is placed, a powder bed forming mechanism 30 that forms a powder bed PB that is the powder P1 spread evenly on the plate main surface 51a, a beam source 3b for irradiating the powder bed PB with an energy beam. The powder bed forming mechanism 30 has a powder supply mechanism 31 that supplies the powder P1, a powder coating mechanism 32 that spreads evenly the powder P1 supplied from the powder supply mechanism 31 on the plate main surface 51a by moving relatively to the start plate 51 toward a clock direction CW, and a powder amount measurement meter 33 placed in front of the powder coating mechanism 32 in a moving direction of the powder coating mechanism 32 relative to the start plate 51, after being supplied from the powder supply mechanism 31, and before evenly spreading by the powder coating mechanism 32 measures an amount of the powder P1.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a layered manufacturing apparatus and a powder bed forming apparatus.

Background Art

[0002] A layered manufacturing apparatus partially solidifies leveled powder by irradiating an energy beam. Therefore, as a basic component, the layered manufacturing apparatus includes a component for leveling the powder. Such a component may be called a blade. Patent Document 1 discloses a blade device. This blade device includes a strip for leveling the powder. Further, the blade device includes a sensor array for monitoring the distance from the powder to the blade device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Layered manufacturing repeats powder leveling and energy beam irradiation. By this repetition, a three-dimensional shaped object is formed. In order to obtain a three-dimensional shaped object, the powder leveling operation is performed multiple times. It is desired that the state such as the thickness of the powder layer formed for each powder leveling operation is stable over a plurality of operations. By stabilizing the leveling operation, it becomes possible to stably continue the shaping process including the leveling operation.

[0005] The present disclosure describes a layered manufacturing apparatus and a powder bed forming apparatus capable of stably continuing a shaping process.

Means for Solving the Problems

[0006] The additive manufacturing apparatus of the present disclosure includes a plate including at least a plate main surface on which powder is placed, a powder bed forming unit that forms a powder bed which is powder evenly spread on the plate main surface, and an irradiation unit that irradiates an energy beam onto the powder bed. The powder bed forming unit includes a supply unit that supplies powder, an application unit that levels the powder supplied from the supply unit on the plate main surface by moving relative to the plate in a predetermined direction, and a measurement unit that is disposed in front of the application unit in the moving direction of the application unit with respect to the plate and measures the amount of powder after being supplied from the supply unit and before being leveled by the application unit.

[0007] The powder bed forming unit of the additive manufacturing apparatus arranges a measurement unit that measures the amount of powder in front of the application unit that levels the powder on the plate main surface. According to this configuration, it is possible to measure the amount of powder after being supplied from the supply unit and before being leveled by the application unit. Since information regarding the amount of powder before leveling can be obtained, it becomes possible to control the supply amount of powder from the supply unit based on this information. A state suitable for leveling is realized, so that a desired powder bed can be stably formed by the leveling operation of the application unit. Therefore, the manufacturing process can be stably continued.

[0008] The plate of the additive manufacturing apparatus of the present disclosure may rotate about a predetermined rotation axis, and relative movement of the application unit with respect to the plate may occur due to the rotation of the plate. According to this configuration, rotary additive manufacturing can be performed.

[0009] The additive manufacturing apparatus of the present disclosure may be arranged in the order of the supply unit, the measurement unit, the application unit, and the irradiation unit from upstream to downstream in the rotation direction of the plate. According to this configuration, due to the rotation of the plate, the supply of powder from the supply unit, the measurement of the amount of powder by the measurement unit, the leveling of the powder by the application unit, and the irradiation of the energy beam onto the powder bed can be continuously performed in this order.

[0010] The measurement unit of the additive manufacturing apparatus of the present disclosure may be sandwiched between the supply unit and the coating unit. According to this configuration, the measurement unit can be protected from the surrounding heat by the supply unit and the coating unit. As a result, good measurement values can be obtained.

[0011] The supply unit, the measurement unit, and the coating unit of the additive manufacturing apparatus of the present disclosure may extend from the rotation axis toward the outer peripheral edge of the plate. According to this configuration, a powder bed can be uniformly formed on the disk-shaped plate.

[0012] In the additive manufacturing apparatus of the present disclosure, the amount of powder supplied by the supply unit on the rotation center side of the plate may be less than the amount of powder supplied by the supply unit on the outer peripheral edge side of the plate. According to this configuration, the supply unit supplies an amount of powder corresponding to the radial direction in the disk-shaped plate. As a result, a radially uniform powder bed can be formed.

[0013] The additive manufacturing apparatus of the present disclosure may further include a control unit that receives a measurement signal from the measurement unit and outputs a control signal to the supply unit. The control unit may generate a control signal for controlling the amount of powder supplied by the supply unit based on a measurement signal regarding the amount of powder output by the measurement unit. According to this configuration, the supply unit can supply an amount of powder suitable for the leveling operation.

[0014] The powder bed forming apparatus of the present disclosure forms a powder bed for an additive manufacturing apparatus including at least a plate including a main surface of the plate on which powder is placed, and an irradiation unit that irradiates an energy beam onto the powder bed that is powder leveled on the main surface of the plate. The powder bed forming apparatus includes a supply unit that supplies powder, a coating unit that levels the powder supplied from the supply unit on the main surface of the plate by moving relative to the plate in a predetermined direction, and a measurement unit that is disposed in front of the coating unit in the moving direction of the coating unit with respect to the plate and measures the amount of powder after being supplied from the supply unit and before being leveled by the coating unit.

[0015] The powder bed forming device arranges a measuring unit for measuring the amount of powder in front of the coating unit that spreads the powder evenly on the main surface of the plate. According to this configuration, it is possible to measure the amount of powder after being supplied from the supply unit and before being spread evenly by the coating unit. Since information regarding the amount of powder before spreading evenly can be obtained, it becomes possible to control the supply amount of powder from the supply unit based on this information. Since a state suitable for spreading evenly is realized, a desired powder bed can be stably formed by the spreading operation of the coating unit. Therefore, the shaping process can be stably continued.

Advantages of the Invention

[0016] The additive manufacturing apparatus and the powder bed forming device of the present disclosure can stably continue the shaping process.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the laminated manufacturing apparatus and the powder bed forming apparatus of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0019] The three-dimensional rotational laminated object manufacturing apparatus (hereinafter referred to as "laminated manufacturing apparatus 1") shown in FIG. 1 is a so-called 3D printer that manufactures a shaped object PA from powder P1. The laminated manufacturing apparatus 1 employs an electron beam as an energy beam. That is, the laminated manufacturing apparatus 1 employs a so-called electron gun powder bed melting method.

[0020] The powder P1 is a metal powder, such as a titanium-based metal powder, an Inconel powder, or an aluminum powder. Further, the powder P1 is not limited to metal powders. The powder P1 may be a powder containing carbon fiber and resin, such as CFRP (Carbon Fiber Reinforced Plastics). Further, the powder P1 may be other powders having conductivity. Note that the powder in the present disclosure is not limited to those having conductivity. For example, when a laser is used as the energy beam, the powder P1 does not have to have conductivity.

[0021] The additive manufacturing apparatus 1 applies energy to the powder P1. In other words, the additive manufacturing apparatus 1 raises the temperature of the powder P1. As a result, the powder P1 melts or sinters. Then, when the additive manufacturing apparatus 1 stops applying energy, the temperature of the powder P1 drops, so it solidifies. That is, the additive manufacturing apparatus 1 manufactures the shaped object PA by repeating the application and stop of energy a plurality of times. Note that "solidifying the powder P1" as used in this embodiment includes a mode in which the powder P1 that has been heated to a temperature higher than the melting point becomes a liquid and then solidifies, and a mode in which the powder P1 sinters by being heated to a temperature lower than the melting point. The shaped object PA is, for example, a mechanical part. The shaped object PA may be other structures.

[0022] The additive manufacturing apparatus 1 includes a drive unit 2, a shaping processing unit 3A, a controller 4 (control unit), and a housing 5. The drive unit 2 realizes various operations required for shaping. The shaping processing unit 3A obtains the shaped object PA by processing the powder P1. Specifically, the processing of the powder P1 includes the supply processing of the powder P1, the preheating processing of the powder P1, and the shaping processing of the powder P1. The housing 5 is supported by a plurality of columns. The housing 5 forms a shaping space S. The shaping space S is an airtight space that can be depressurized for processing the powder P1 by the shaping processing unit 3.

[0023] In the shaping space S, a start plate 51 and a shaping tank 52 are arranged. The start plate 51 is a processing table on which the shaping process is performed. The start plate 51 has, for example, a disc shape, and the powder P1, which is the raw material of the shaped object PA, is arranged thereon. The start plate 51 may be arranged such that its central axis overlaps with the central axis of the housing 5. The drive unit 2 is connected to the start plate 51. Therefore, the start plate 51 rotates and moves linearly along the rotation axis by the drive unit 2.

[0024] The drive unit 2 rotates and raises and lowers the start plate 51. The drive unit 2 has a rotational drive mechanism 21 and a lifting drive mechanism 22. The rotational drive mechanism 21 rotates the start plate 51. The upper end of the rotational drive mechanism 21 is connected to the start plate 51. The lower end of the rotational drive mechanism 21 is attached to the drive source. The lifting drive mechanism 22 relatively raises and lowers the start plate 51 with respect to the shaping tank 52. This lifting and lowering is along the rotation axis of the rotational drive mechanism 21. Note that the drive unit 2 may be any mechanism that can rotate and raise and lower the start plate 51, and the drive unit 2 is not limited to the above mechanism.

[0025] FIG. 2 shows an enlarged view of the main components used in the shaping process. On the start plate 51, shaping processing units 3A and 3B are arranged. That is, the shaping processing units 3A and 3B face the plate main surface 51a of the start plate 51. The shaping processing units 3A and 3B are arranged at equal intervals (180 degrees) around the rotation axis. In other words, the shaping processing units 3A and 3B are arranged equidistantly, for example, in the circumferential direction. According to this arrangement, the lamination thickness of the powder P1 can be made uniform according to the rotation angle to the next processing area. Note that the arrangement of the shaping processing units 3A and 3B described above is an example and is not limited to this configuration. For example, the shaping processing units 3A and 3B may be arranged at different angles in the circumferential direction.

[0026] The shaping processing units 3A and 3B only differ in the positions where they are arranged, and their specific components are the same. Note that the components of the shaping processing units 3A and 3B may be different from each other. For example, one of the shaping processing units 3A and 3B may be such that the other omits a part of its components. Hereinafter, the shaping processing unit 3A will be described in detail.

[0027] The shaping processing unit 3A includes a powder bed forming mechanism 30 (powder bed forming part, powder bed forming device), a heater 3a, and a beam source 3b (irradiation part). The powder bed forming mechanism 30 forms a powder bed PB. The heater 3a performs pre-treatment of the powder bed PB. The beam source 3b performs a shaping process of irradiating an energy beam onto the powder bed PB.

[0028] The powder bed forming mechanism 30 forms the powder bed PB on the start plate 51. The powder bed forming mechanism 30 includes a powder supply mechanism 31, a powder coating mechanism 32, and a powder amount measuring device 33. The powder supply mechanism 31 stores the powder P1 and supplies the powder P1 onto the start plate 51. The powder coating mechanism 32 levels the surface of the powder P1 on the start plate 51. The powder amount measuring device 33 measures the amount of the powder P1 before it is leveled by the powder coating mechanism 32. The powder bed forming mechanism 30 will be described in detail later.

[0029] The heater 3a raises the temperature of the powder P1 by radiant heat. As the heater 3a, for example, an infrared heater may be used, or for example, a gas heater may be used. The preheating here means a process of heating so that the temperature of the powder P1 in the preheating region is higher than that of the powder P1 in the supply region. Such a heat treatment may be, for example, a process of pre-sintering the powder P1. Pre-sintering means a state in which the powders P1 are diffused and joined at the minimum point by a diffusion phenomenon. The heater 3a, as an example, heats the powder P1 to a temperature of at least half of the melting point of the powder P1. This is based on the fact that the diffusion phenomenon of sintering generally becomes active at a temperature of at least half of the melting point. For example, when the powder P1 is titanium, the pre-sintering temperature is 700°C or higher and 800°C or lower. Note that the melting point of the titanium alloy is about 1500°C or higher and 1600°C or lower. Also, when the powder P1 is aluminum, the pre-sintering temperature is 300°C. Note that the melting point of aluminum is about 660°C.

[0030] The beam source 3b generates an electron beam. The electron beam is irradiated onto the powder P1. The beam source 3b is, for example, an electron gun. The electron gun generates an electron beam according to the potential difference generated between the cathode and the anode. The region on the main surface 51a of the plate irradiated with the electron beam is a region that raises the temperature of the powder P1. The temperature is higher than the temperature of the powder P1 preheated by the heater 3a. That is, the temperature of the powder P1 irradiated with the electron beam is a temperature (sintering temperature or melting temperature) at which the shaped article PA can be formed. The beam source 3b scans and irradiates the electron beam to a desired portion.

[0031] The powder bed forming mechanism 30, the heater 3a, and the beam source 3b are arranged in this order along the rotation direction (clockwise CW) of the start plate 51. In the following description, "upstream" and "downstream" are based on the rotation direction of the start plate 51.

[0032] The start plate 51 rotates in the clockwise direction CW. Then, when a certain point is assumed on the start plate 51, as the start plate 51 rotates, the point passes through the powder bed forming mechanism 30, the heater 3a, and the beam source 3b in this order.

[0033] The controller 4 controls the rotational drive mechanism 21. As a result, the start plate 51 rotates in the clockwise direction CW at a constant rotational speed. This rotational speed may be determined by the temperature rise width in the preheating region and the shaping region. For example, the amount of energy required to raise the temperature of the powder P1 before preheating to a predetermined temperature after preheating is obtained. Next, the required time required to apply the energy amount to the powder P1 is determined. Then, based on the required time and the length of the trajectory passed through when passing through the preheating region, the rotational speed is obtained. The controller 4 controls the lifting drive mechanism 22. As a result, the start plate 51 continuously moves downward (separation operation) over time. The moving speed of the start plate 51 may be determined by the thickness of the layer formed each time the start plate 51 makes one rotation (that is, the thickness of the powder bed PB). The controller 4 controls the powder bed forming mechanism 30. The operation of forming the powder bed PB will be described in detail later when the controller 4 controls the powder bed forming mechanism 30.

[0034] Hereinafter, the powder bed forming mechanism 30 will be described in detail. The powder bed forming mechanism 30 includes a powder supply mechanism 31 (supply unit), a powder coating mechanism 32 (coating unit), and a powder measuring instrument 33 (measuring unit).

[0035] The powder supply mechanism 31 in FIG. 3 conveys the powder P1 by the rotation of the roller 311. The powder supply mechanism 31 includes a roller 311, a hopper 312, and a casing 313. The powder supply mechanism 31 configured by such components is called a roller feeder. Note that the powder supply mechanism 31 may adopt a configuration different from that of the roller feeder. For example, the powder supply mechanism 31 may adopt a screw feeder. In the case of a screw feeder, a plurality of powder discharge ports are provided along the radial direction of the start plate 51. According to the arrangement of the discharge ports, a pseudo-linearly uniform supply of the powder P1 can be realized.

[0036] The hopper 312 is a container for storing the powder P1. The hopper 312 supplies the powder P1 to the casing 313. The outlet of the hopper 312 is connected to the inlet of the casing 313. In the example shown in FIG. 3, the hopper 312 and the casing 313 form an integral container. The casing 313 supplies the powder P1 provided from the hopper 312 to the roller 311. Further, the casing 313 may include a support portion that rotatably supports the roller 311 and a drive portion that rotates the roller 311.

[0037] The roller 311 is housed inside the casing 313, and a part of its circumferential surface is exposed. The roller 311 is rotationally driven by a drive motor which is a drive portion, and rotates about the rotation axis. A gap G is formed between the circumferential surface 311a of the roller 311 and the lower end of the casing 313. The circumferential surface 311a of the roller 311 is preferably rough. The roller 311 has a shape and size (i.e., diameter) that can maintain the state where the powder P1 is deposited on the circumferential surface 311a. As the roller 311 rotates, it moves the circumferential surface 311a in the circumferential direction. The conveyance direction in this case is arc-shaped. The movement amount of the conveyance surface is the movement amount of the circumferential surface 311a of the roller 311, and is determined by the radius and rotation angle of the roller 311. The roller 311 rotates by a predetermined rotation angle when the drive motor is controlled by the controller 4. By this rotation, the circumferential surface 311a is inverted at the front end portion. At this time, the powder P1 deposited on the circumferential surface 311a with a thickness corresponding to the gap falls from the front end portion.

[0038] In the powder supply device provided with a roller type conveyance device, the diameter of the roller 311 may be changed in the axial direction. By doing so, the gap G can be changed in the radial direction of the start plate 51. For example, the roller 311 may be configured such that its diameter decreases from the center toward the outer periphery in the radial direction of the start plate 51. With this configuration, the height of the gap G becomes larger at the central portion than at the axial end portions of the roller 311. Since the height of the gap G changes gradually, the powder can be supplied with an appropriate supply amount.

[0039] The powder application mechanism 32 shown in FIG. 4 levels the powder P1 that has fallen onto the main surface 51a of the plate from the powder supply mechanism 31. Here, "leveling" means forming a layer of the powder P1 having a predetermined thickness on the shaping surface. And this layer of the powder P1 is referred to as a powder bed PB.

[0040] The powder application mechanism 32 has a rake blade 321 and a body 322. The rake blade 321 is a part that contacts the powder P1. The rake blade 321 may be a thin metal plate. The body 322 holds the blade base end 321f of the rake blade 321. The body 322 is stationary with respect to the shaping space S. By the body 322 holding the rake blade 321, the rake blade 321 can also be stationary with respect to the shaping space S. The rake blade 321 does not move in the direction of the pressing force.

[0041] The blade tip 321e of the rake blade 321 is separated from the surface to be treated PL by a predetermined height. The surface to be treated PL means, for example, the surface of the powder bed PB after being partially irradiated with an energy beam in the shaping processing unit 3A and before receiving the supply of the powder P1 from the powder supply mechanism 31 in the downstream shaping processing unit 3B.

[0042] When the powder P1 falls onto the surface PL to be processed, the powder P1 accumulates on the surface PL to be processed. The height of the accumulated powder P1 is greater than the thickness of the powder bed PB. Then, the blade front surface 321a of the rake blade 321 is pressed against the accumulated powder P1. This pressing occurs when the start plate 51 rotates with respect to the stationary rake blade 321. Then, among the accumulated powder P1, the powder P1 existing between the surface PL to be processed and the blade tip 321e moves to the back side of the rake blade 321. On the other hand, among the powder P1 on the back side of the rake blade 321, the powder P1 existing above the blade tip 321e is blocked by the rake blade 321 and thus cannot move to the side of the blade back surface 321b. Therefore, a powder bed PB, which is a layer of powder P1 having the same thickness PBt as the gap between the surface PL to be processed and the blade tip 321e, is formed.

[0043] In the following description, on the side of the blade front surface 321a of the rake blade 321, the portion that accumulates so as to be higher than the surface of the powder bed PB is referred to as a "powder lump PD". That is, the powder lump PD is formed by the powder P1. The powder P1 that forms the powder lump exists above the blade tip 321e and thus cannot move to the side of the blade back surface 321b. Further, the amount of the powder lump PD is defined as the "powder lump amount". The powder lump amount may be a volume or a weight.

[0044] Also, the "supply amount" is defined as the volume or weight of the powder P1 supplied per unit time from the powder supply mechanism 31. Further, the "powder bed amount" is defined as the volume or weight of the powder P1 that moves per unit time to the downstream side of the powder coating mechanism 32 as the powder bed PB. The powder lump amount is determined by the difference between the supply amount and the powder bed amount. For example, when the supply amount is greater than the powder bed amount, the powder lump amount gradually increases. Conversely, when the supply amount is less than the powder bed amount, the powder lump amount gradually decreases. Further, when the supply amount is equal to the powder bed amount, the powder lump amount does not increase or decrease.

[0045] For example, assume that the amount of powder pile decreases over time and the height of the deposited powder P1 becomes lower than the height from the surface to be treated PL to the tip of the blade 321e. In this case, a powder bed PB having a desired thickness cannot be formed in the first place.

[0046] Conversely, assume that the amount of powder pile increases over time. In this case, coating defects occur. Coating defects mean that noticeable unevenness has occurred on the surface of the powder bed PB. This coating defect will be described in detail.

[0047] FIG. 5 is a cross-sectional view showing a state in which several layers are formed on the start plate 51. An unsintered layer P2 made of unsintered powder P1 is formed on the main surface 51a of the plate. A semi-sintered layer P3 made of semi-sintered powder P1 is formed on the unsintered layer P2. And in this FIG. 5, the surface of the semi-sintered layer P3 corresponds to the surface to be treated PL. Now, assume that unsintered powder P1 is supplied from the powder supply mechanism 31 to the surface of the semi-sintered layer P3 which is the surface to be treated PL, and the supply amount is larger than the powder bed amount, and the amount of powder pile is gradually increasing.

[0048] As shown in FIG. 5, when the amount of powder pile increases, the pressing force acting on the surface to be treated PL due to the powder pile PD increases. This pressing force affects the interfacial frictional force R1 acting between the surface to be treated PL and the contact surface where the powder pile PD is in contact. Since the pressing force is the normal force, when the pressing force increases, the interfacial frictional force R1 between the semi-sintered layer P3 and the powder P1 forming the powder pile also increases. In such a state, when the powder pile PD receives a pressing force along the traveling direction from the rake blade 321, a large interfacial frictional force R1 is generated between the semi-sintered layer P3 and the powder pile PD.

[0049] On the other hand, wall surface frictional force R2 also occurs between the main surface 51a of the plate and the green layer P2. However, even if the vertical resistance force is the same, the state between the semi-sintered layer P3 and the powder pile PD is different from the state between the main surface 51a of the plate and the green layer P2. Therefore, the magnitude of the interfacial frictional force R1 generated between the semi-sintered layer P3 and the powder pile PD is different from the magnitude of the wall surface frictional force R2 generated between the main surface 51a of the plate and the green layer P2. In the following description, the frictional force generated between the semi-sintered layer P3 and the powder pile PD is simply referred to as "interfacial frictional force R1". Similarly, the frictional force generated between the main surface 51a of the plate and the green layer P2 is simply referred to as "wall surface frictional force R2".

[0050] First, assume that the magnitude of the interfacial frictional force R1 is smaller than the wall surface frictional force R2. This assumption holds when the amount of the powder pile is small. In this case, when the powder pile PD receives a pressing force from the rake blade 321, slipping occurs between the semi-sintered layer P3 and the powder pile PD. At this time, no slipping occurs between the main surface 51a of the plate and the green layer P2. In this case, coating defects do not occur.

[0051] Conversely, assume that the magnitude of the interfacial frictional force R1 is larger than the wall surface frictional force R2. This assumption holds when the amount of the powder pile is large. In this case, when the powder pile PD receives a pressing force from the rake blade 321, the large interfacial frictional force R1 makes it difficult for slipping to occur between the semi-sintered layer P3 and the powder pile PD. Then, slipping occurs between the main surface 51a of the plate and the green layer P2 without slipping occurring between the semi-sintered layer P3 and the powder pile PD. In this case, coating defects occur.

[0052] Therefore, the amount of the powder pile PD (powder pile amount) needs to be maintained within a predetermined range. The powder pile amount is not allowed to be less than the lower limit, nor is it allowed to be more than the upper limit. That is, it is necessary to increase or decrease the supply amount from the powder supply mechanism 31 according to the powder pile amount. Since the control of the supply amount is based on the powder pile amount, it is necessary to measure the powder pile amount. Therefore, the powder bed forming mechanism 30 has a powder amount measuring instrument 33 for measuring the powder pile amount.

[0053] The powder measuring device 33 shown in FIG. 4 measures the amount of powder pile. The amount of powder pile can be treated as the volume of the deposited powder P1 or the weight of the deposited powder P1. On the other hand, the powder measuring device 33 does not directly measure the volume or weight of the powder P1. The powder measuring device 33 obtains data regarding a measurement item different from the volume or weight of the powder P1. Then, using the data, the volume or weight of the powder P1 is obtained. Note that the powder measuring device 33 may only acquire data regarding a measurement item different from the volume or weight of the powder P1. That is, the powder measuring device 33 may not be provided with a function of converting data regarding another measurement item into the volume or weight of the powder P1. In this case, the function of converting data regarding another measurement item into the volume or weight of the powder P1 may be performed by the controller 4.

[0054] The measurement item directly measured by the powder measuring device 33 is the powder height H or the powder width W. The powder measuring device 33 measures at least one of the powder height H and the powder width W. In the present disclosure, the powder height H is exemplified as the measurement item. A mode in which the powder width W is the measurement item will be described as a modification.

[0055] As an example, the powder height H is the distance along the normal direction of the main surface 51a of the plate from the powder bed surface PBs to the surface of the powder pile PD (hereinafter referred to as "powder pile surface PDs"). As the powder pile surface PDs, any position may be selected in the powder P1 located in front of the rake blade 321. For example, it may be the slope PDs1 formed immediately before the rake blade 321. Further, it may be the flat surface PDs2 formed further in front of the slope PDs1. Also, a reference different from the powder bed surface PBs may be used as the reference for the powder height H. The tip 321e of the blade of the rake blade 321 can also be adopted as the reference for the powder height H. In this case, the powder height H is the distance along the normal direction N from the blade tip 321e to the powder pile surface PDs.

[0056] Note that in the normal direction N, the position of the blade tip 321e is substantially the same as the position of the powder bed PB. Therefore, the definition of the powder height H as the distance from the blade tip 321e to the powder lump surface PDs is substantially the same as the definition of the powder height H as the distance from the powder bed surface PBs to the powder lump surface PDs. Also, for example, the main surface 51a of the plate can be adopted as a reference for the powder height H. In this case, the powder height H is the distance from the main surface 51a of the plate to the powder lump surface PDs.

[0057] As an example, the powder amount measuring device 33 can use a laser rangefinder. According to the laser rangefinder, the distance from the emission position of the laser L to the powder lump surface PDs can be obtained. Since the relative position of the powder amount measuring device 33 with respect to the powder application mechanism 32 can be uniquely known, the distance from the emission position to the blade tip 321e of the rake blade 321 can be known. Therefore, the powder height H can be obtained by subtracting the distance from the emission position of the laser L to the powder lump surface PDs from the distance to the blade tip 321e of the rake blade 321.

[0058] Note that the specific configuration of the powder amount measuring device 33 is not limited to the laser rangefinder. The powder amount measuring device 33 may adopt a non-contact method of measuring the powder height H without contacting the powder P1, like a laser rangefinder. The powder amount measuring device 33 may also adopt a contact method of measuring the powder height H by contacting the powder P1. Other examples will be described in the modification examples described later.

[0059] Next, the operation of forming the powder bed by the powder bed forming mechanism 30 will be described with reference to the flowchart shown in FIG. 6.

[0060] First, the controller 4 acquires a set value (step S1). This set value is a value for determining whether the supply amount should be increased or decreased. Specifically, it is a threshold value for the amount of powder accumulation. In step S1, an appropriate set value may be selected from a plurality of pre-prepared set values based on manufacturing conditions such as the thickness of the powder bed PB. Alternatively, in step S1, the set value may be calculated based on separately input manufacturing conditions.

[0061] Next, the controller 4 outputs a control signal to cause the powder supply mechanism 31 to supply the powder P1 (step S2). Also, the controller 4 starts the rotation of the start plate 51 by outputting a control signal.

[0062] Next, the controller 4 obtains the amount of powder accumulation (step S3). First, the controller 4 obtains the distance from the powder amount measuring device 33 to the surface PDs of the powder accumulation. Next, the controller 4 calculates the powder height H using the distance. Next, the controller 4 converts the powder height H into the amount of powder accumulation.

[0063] Next, the controller 4 compares the amount of powder accumulation, which is the amount of powder before coating, with the set value (step S4). Specifically, the controller 4 determines whether the amount of powder accumulation is greater than the set value. As a result of the comparison in step S4, if the amount of powder accumulation is greater than the set value (step S4: YES), the controller 4 reduces the supply amount from the powder supply mechanism 31 by outputting a control signal (step S5). As a result of the comparison in step S4, if the amount of powder accumulation is less than the set value (step S4: NO), the controller 4 increases the supply amount from the powder supply mechanism 31 by outputting a control signal (step S6).

[0064] Note that in addition to the binary control of increasing or decreasing the supply amount, the controller 4 may perform ternary control of increasing the supply amount, decreasing the supply amount, and maintaining the supply amount.

[0065] Thereafter, due to the rotation of the start plate 51, the powder dam PD reaches the rake blade 321. As a result, a powder bed PB having a predetermined thickness is formed (step S7).

[0066] Next, the controller 4 determines whether the shaping process is completed (step S8). If the shaping process is not completed (step S8: NO), the process from step S3 is repeated again. If the shaping process is completed (step S8: YES), the overall process ends.

[0067] Hereinafter, the operation and effects of the additive manufacturing apparatus 1 and the powder bed forming mechanism 30 of the present disclosure will be described.

[0068] The additive manufacturing apparatus 1 includes a start plate 51 including at least a plate main surface 51a on which the powder P1 is placed, a powder bed forming mechanism 30 that forms a powder bed PB which is the powder P1 spread evenly on the plate main surface 51a, and a beam source 3b that irradiates an energy beam onto the powder bed PB. The powder bed forming mechanism 30 includes a powder supply mechanism 31 that supplies the powder P1, a powder coating mechanism 32 that moves relative to the start plate 51 in the clockwise direction CW to spread the powder P1 supplied from the powder supply mechanism 31 evenly on the plate main surface 51a, and a powder amount measuring device 33 that is disposed in front of the powder coating mechanism 32 in the moving direction of the powder coating mechanism 32 with respect to the start plate 51 and measures the amount of the powder P1 after being supplied from the powder supply mechanism 31 and before being spread evenly by the powder coating mechanism 32.

[0069] In the powder bed forming mechanism 30 of the additive manufacturing apparatus 1, a powder quantity measuring device 33 for measuring the quantity of powder P1 is arranged in front of a powder coating mechanism 32 that spreads the powder P1 evenly on the main surface 51a of the plate. According to this configuration, it is possible to measure the quantity of powder P1 after being supplied from the powder supply mechanism 31 and before being spread evenly by the powder coating mechanism 32. Since information regarding the quantity of powder P1 before spreading evenly can be obtained, it becomes possible to control the supply quantity of powder P1 from the powder supply mechanism 31 based on this information. A state suitable for spreading evenly is realized, so that a desired powder bed PB can be stably formed by the spreading operation of the powder coating mechanism 32. Therefore, the shaping process can be stably continued.

[0070] The start plate 51 of the additive manufacturing apparatus 1 rotates about a predetermined axis of rotation, and relative movement of the powder coating mechanism 32 with respect to the start plate 51 may occur due to the rotation of the start plate 51. According to this configuration, rotary additive manufacturing can be performed.

[0071] The additive manufacturing apparatus 1 is arranged in the order of the powder supply mechanism 31, the powder quantity measuring device 33, the powder coating mechanism 32, and the irradiation unit from upstream to downstream in the rotation direction of the start plate 51. According to this configuration, due to the rotation of the start plate 51, the supply of powder P1 from the powder supply mechanism 31, the measurement of the quantity of powder P1 by the powder quantity measuring device 33, the spreading of powder P1 by the powder coating mechanism 32, and the irradiation of the energy beam on the powder bed PB can be continuously performed in this order.

[0072] For example, assume that the powder amount measuring device 133 is arranged on the downstream side of the powder coating mechanism 32 as in the comparative example shown in FIG. 10. The powder amount measuring device 133 measures the thickness PBt of the powder bed PB. The entire powder amount measuring device 133 is exposed to the shaping space S. The shaping space S is a vacuum region. Then, the powder amount measuring device 133 is likely to receive heat radiated as electromagnetic waves from the surrounding objects, particularly the powder P1 irradiated with the electron beam. On the other hand, the powder amount measuring device 33 of the additive manufacturing apparatus 1 is sandwiched between the powder supply mechanism 31 and the powder coating mechanism 32. According to this configuration, since the powder amount measuring device 33 is sandwiched between the powder supply mechanism 31 and the powder coating mechanism 32, the exposed surface for receiving radiant heat is reduced. That is, the powder amount measuring device 33 can be protected from the surrounding heat by the powder supply mechanism 31 and the powder coating mechanism 32. As a result, good measurement values can be obtained.

[0073] The powder supply mechanism 31, the powder amount measuring device 33, and the powder coating mechanism 32 of the additive manufacturing apparatus 1 may extend from the rotation axis toward the outer peripheral edge of the start plate 51. According to this configuration, the powder bed PB can be uniformly formed on the disk-shaped start plate 51.

[0074] The additive manufacturing apparatus 1 further includes a controller 4 that receives a measurement signal from the powder amount measuring device 33 and outputs a control signal to the powder supply mechanism 31. The controller 4 generates a control signal for controlling the amount of powder P1 supplied by the powder supply mechanism 31 based on the measurement signal regarding the amount of powder P1 output by the powder amount measuring device 33. According to this configuration, the powder supply mechanism 31 can supply an appropriate amount of powder P1 for the leveling operation.

[0075] According to the additive manufacturing apparatus 1 and the powder bed forming mechanism 30, further effects can also be achieved. FIG. 7 shows an example of a state where the amount of powder accumulation has increased. In the example shown in FIG. 7, although the amount of powder accumulation has increased, it is assumed that coating defects have not occurred. When the amount of powder accumulation increases, the pressing force acting on the rake blade 321 increases. When the pressing force received by the rake blade 321 increases, the rake blade 321 bends toward the downstream side. Since the distance from the blade base end 321f to the blade tip 321e of the rake blade 321 is constant, this bending causes the length along the normal direction from the blade base end 321f to the blade tip 321e to become shorter. As a result, the thickness of the powder bed PB increases by the amount of shortening (thickness DH). In short, when the amount of powder accumulation increases, the thickness PDt of the powder bed PB tends to increase.

[0076] On the other hand, the additive manufacturing apparatus 1 can maintain the amount of powder accumulation within an appropriate range. As a result, the occurrence of bending of the rake blade 321 that affects the thickness of the powder bed PB is suppressed. Therefore, the additive manufacturing apparatus 1 can satisfactorily maintain the thickness of the powder bed PB.

[0077] The additive manufacturing apparatus and the powder bed forming apparatus of the present disclosure are not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0078] FIG. 8 is a perspective view of the additive manufacturing apparatus 1A of the first modification. The additive manufacturing apparatus 1A of the first modification has a configuration of the powder supply mechanism and the powder measuring instrument different from that of the additive manufacturing apparatus 1 of the embodiment. Specifically, the additive manufacturing apparatus 1A of the first modification includes a plurality of powder supply mechanisms 31A1, 31A2, 31A3 arranged along the radial direction of the start plate 51. Further, the additive manufacturing apparatus 1A of the first modification includes a plurality of powder measuring instruments 33A arranged along the radial direction of the start plate 51. One powder supply mechanism 31A3 corresponds to one powder measuring instrument 33A. According to this configuration, the supply amount can be adjusted for each of the powder supply mechanisms 31A1, 31A2, 31A3. The supply amount of the powder supply mechanism 31A1 arranged on the most central side and the supply amount of the powder supply mechanism 31A3 arranged on the outermost peripheral side can be made different from each other. For example, in the additive manufacturing apparatus 1A, the amount of the powder P1 supplied by the powder supply mechanism 31A1 on the rotation center side of the start plate 51 can be made less than the amount of the powder P1 supplied by the powder supply mechanism 31A3 on the outer peripheral edge side of the start plate 51. Therefore, the powder supply mechanism 31A can supply an amount of the powder P1 corresponding to the radial direction in the disk-shaped start plate 51. As a result, a powder bed PB having uniform thickness in the radial direction can be formed.

[0079] The powder measuring instrument 33 of the powder bed forming mechanism 30 adopted a method of measuring the height of the powder using a laser beam. The method adopted by the powder measuring instrument 33 is not limited to this method. Hereinafter, the powder measuring instrument 33 which is the second to sixth modifications will be described.

[0080] FIG. 9(a) shows a powder bed forming mechanism 30B provided in the additive manufacturing apparatus 1B of the second modification. The powder amount measuring device 33B measures the powder height H. The powder amount measuring device 33B is a contact type. Specifically, the powder amount measuring device 33B has an electric probe 33B1 disposed at a predetermined height. Further, the powder amount measuring device 33B has a power supply 33B2 and an ammeter 33B3. The electric probe 33B1, the power supply 33B2, and the ammeter 33B3 are connected in series. And the ammeter 33B3 is connected to the rake blade 321. According to this configuration, an electric probe 33B1, a power supply 33B2, an ammeter 33B3, and a rake blade 321 constitute a contact detection circuit. Since the electric probe 33B1 does not directly contact the rake blade 321, normally, no current flows through the circuit. However, when the amount of powder accumulation increases, the powder accumulation PD contacts the rake blade 321 and also contacts the electric probe 33B1. Then, the electric probe 33B1 and the rake blade 321 become conductive. As a result, current flows through the circuit. Triggered by the flow of this current, it is possible to know that the amount of powder accumulation has reached the threshold value.

[0081] FIG. 9(b) shows a powder bed forming mechanism 30C provided in the additive manufacturing apparatus 1C of the third modification. The powder amount measuring device 33C measures the powder height H. The powder amount measuring device 33C is a contact type. Specifically, the powder amount measuring device 33C has a temperature probe 33C1 and a thermometer 33C2. The temperature probe 33C1 is disposed at the same position as the electric probe 33B1 of the second modification. When the amount of powder accumulation increases, the powder accumulation PD contacts the temperature probe 33C1. This contact causes a discontinuous change in the temperature data output by the thermometer 33C2. Triggered by this discontinuous change, it is possible to know that the amount of powder accumulation has reached the threshold value.

[0082] FIG. 9(c) shows the powder bed forming mechanism 30D included in the additive manufacturing apparatus 1D of the third modification. The powder amount measuring device 33D measures the powder width W. Specifically, the powder amount measuring device 33D includes a foil plate 33D1 and a laser rangefinder 33D2. The foil plate 33D1 is disposed in front of the rake blade 321. The foil plate 33D1 may be attached to the housing of the powder applying mechanism 32D. The foil plate 33D1 is more deformable than the rake blade 321. Also, the tip of the foil plate 33D1 is at a position higher than the blade tip 321e. When the amount of powder accumulation increases, the powder width W becomes longer. When the powder width W becomes longer, the foil plate 33D1 is pressed by the powder P1, so the foil plate 33D1 deforms forward. This deformation is detected by the laser rangefinder 33D2. Even with such a configuration, the powder width W can be obtained.

[0083] FIG. 9(d) shows the powder bed forming mechanism 30E included in the additive manufacturing apparatus 1E of the fourth modification. The powder amount measuring device 33E measures the powder width W. The powder amount measuring device 33E includes a foil plate 33E1 and a contact detection circuit 33E2. The foil plate 33E1 has the same configuration as the foil plate 33D1 of the third modification. In the fourth modification, the configuration for detecting the deformation of the foil plate 33E1 is different from that of the third modification. In the fourth modification, the deformation of the foil plate 33E1 is detected electrically. The contact detection circuit 33E2 includes a contact 33E3, a power source 33E4, and an ammeter 33E5. When the deformed foil plate 33E1 contacts the contact 33E3, the contact detection circuit 33E2 becomes conductive and current flows through the circuit. Using the flow of this current as a trigger, it is possible to know that the amount of powder accumulation has reached the threshold value.

[0084] Figs. 9(e) and 9(f) show the powder bed forming mechanism 30F provided in the additive manufacturing apparatus 1F of the fifth modification. The powder quantity measuring instrument 33F measures the powder height H or the powder width W. In the fifth modification, it is detected by a laser that the powder width W has reached a threshold value. Specifically, the powder quantity measuring instrument 33F includes a laser light source 33F1 arranged on the center side along the radial direction and a light receiving sensor 33F2 arranged on the outer peripheral side. In the examples of Figs. 9(e) and 9(f), it is assumed that the laser L is irradiated from the back side of the paper surface toward the front side of the paper surface. When the amount of powder lumps is small, the laser L is not blocked by the powder P1, so it can be detected by the light receiving sensor 33F2 (see Fig. 9(e)). On the other hand, when the amount of powder lumps is large, the laser L is blocked by the powder P1, so it cannot be detected by the light receiving sensor 33F2 (see Fig. 9(f)). In this light receiving sensor 33F2, when the laser that has been detected is no longer detected, it can be known that the amount of powder lumps has reached the threshold value using this as a trigger.

Explanation of Signs

[0085] 1, 1A, 1B, 1C, 1D, 1E, 1F Additive manufacturing apparatus 2 Drive unit 3 Forming processing unit 3A Forming processing unit 3a Heater 3B Forming processing unit 3b Beam source, beam source (irradiation unit) 4 Controller (control unit) 5 Housing 7 Column 21 Rotation drive mechanism 22 Lifting drive mechanism 30, 30B, 30C, 30D, 30E, 30F Powder bed forming mechanism (powder bed forming part, powder bed forming apparatus) 31, 31A, 31A1, 31A3 Powder supply mechanism (supply part) 32, 32D Powder coating mechanism (coating part) 33, 33A, 33B, 33C, 33D, 33E, 33F Powder quantity measuring instrument (measurement part) 51 Start plate (plate) Main surface of the 51a plate 52 Shaping tank P1 Powder PA Shaped object PB Powder bed H Powder height W Powder width

Claims

1. A plate including at least a main surface of the plate on which powder is placed, the plate rotating about a predetermined axis of rotation; A powder bed forming unit that forms a powder bed which is the powder spread evenly on the main surface of the plate; An irradiation unit that irradiates an energy beam onto the powder bed, and comprising: The powder bed forming unit includes: A supply unit that supplies the powder; An application unit that moves relative to the plate in a predetermined direction to spread evenly on the main surface of the plate the powder supplied from the supply unit; A measurement unit that is disposed in front of the application unit in the moving direction of the application unit with respect to the plate, and measures the amount of the powder after being supplied from the supply unit and before being spread evenly by the application unit; and having Due to the rotation of the plate, relative movement of the application unit with respect to the plate occurs; A laminated manufacturing apparatus in which the supply unit, the measurement unit, the application unit, and the irradiation unit are arranged in this order from upstream to downstream in the rotation direction of the plate.

2. The measurement unit is sandwiched between the supply unit and the application unit. The laminated manufacturing apparatus according to claim 1.

3. The supply unit, the measurement unit, and the application unit extend from the axis of rotation toward the outer peripheral edge of the plate. The laminated manufacturing apparatus according to claim 2.

4. The amount of the powder supplied by the supply unit on the rotation center side of the plate is less than the amount of the powder supplied by the supply unit on the outer peripheral edge side of the plate. The laminated manufacturing apparatus according to claim 3.

5. Further comprising a control unit that receives a measurement signal from the measurement unit and outputs a control signal to the supply unit, The control unit generates the control signal for controlling the amount of the powder supplied by the supply unit based on the measurement signal regarding the amount of the powder output by the measurement unit. The laminated manufacturing apparatus according to any one of claims 1 to 4.

6. A powder bed forming apparatus for forming the powder bed of a laminated manufacturing apparatus including at least a main surface of the plate on which powder is placed, the plate rotating about a predetermined axis of rotation, and an irradiation unit that irradiates an energy beam onto the powder bed which is the powder spread evenly on the main surface of the plate, A supply unit that supplies the powder; An application unit that moves relative to the plate in a predetermined direction to spread evenly on the main surface of the plate the powder supplied from the supply unit; A measuring unit that is disposed in front of the coating unit in the moving direction of the coating unit with respect to the plate and measures the amount of the powder after being supplied from the supply unit and before being spread by the coating unit. Due to the rotation of the plate, relative movement of the coating unit with respect to the plate occurs. The supply unit, the measuring unit, and the coating unit are disposed upstream of the irradiation unit in the rotation direction of the plate. A powder bed forming apparatus, which is arranged in the order of the supply unit, the measuring unit, and the coating unit from upstream to downstream in the rotation direction of the plate.

Images