JP2023007774A - Laminate molding device and powder bed forming device - Google Patents

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

The present disclosure relates to additive manufacturing apparatus and powder bed forming apparatus.

The layered manufacturing apparatus partially hardens the evenly spread powder by irradiating it with an energy beam. Therefore, the layered manufacturing apparatus has, as a basic component, a part for spreading the powder evenly. Such parts are sometimes called blades. US Pat. No. 6,200,000 discloses a blade instrument. The blade device is equipped with strips for leveling the powder. Additionally, the blade instrument is equipped with a sensor array that monitors the distance from the powder to the blade instrument.

Japanese Patent Application Laid-Open No. 2019-32050

Laminate manufacturing repeats powder spreading and energy beam irradiation. A three-dimensional modeled object is formed by this repetition. In order to obtain a three-dimensional model, the powder is spread evenly several times. It is desired that the state of the powder layer, such as the thickness, be stable over a plurality of operations for the powder layer formed for each powder spreading operation. By stabilizing the spreading motion, it becomes possible to stably continue the modeling process including the spreading motion.

The present disclosure describes an additive manufacturing apparatus and a powder bed forming apparatus that can stably continue the manufacturing process.

A layered manufacturing apparatus according to 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 that is powder spread evenly on the plate main surface, and an energy beam on the powder bed. and an irradiating unit that irradiates. The powder bed forming unit includes a supply unit that supplies powder, and an application unit that spreads the powder supplied from the supply unit over the main surface of the plate by moving relative to the plate in a predetermined direction. and a measuring unit arranged in front of the applying unit in the moving direction of the applying unit with respect to the plate and measuring the amount of powder after being supplied from the supplying unit and before being spread evenly by the applying unit.

The powder bed forming unit of the layered manufacturing apparatus has a measuring unit that measures the amount of powder in front of the coating unit that spreads the powder evenly over the main surface of the plate. According to this configuration, it is possible to measure the amount of powder before it is evenly spread by the application section after being supplied from the supply section. Since it is possible to obtain information about the amount of powder before spreading, it is possible to control the amount of powder supplied from the supply section based on the information. Since a state suitable for even spreading is realized, a desired powder bed can be stably formed by the spreading operation of the application unit. Therefore, the modeling process can be stably continued.

The plate of the additive manufacturing apparatus of the present disclosure may rotate about a predetermined axis of rotation, and rotation of the plate may cause relative movement of the applicator with respect to the plate. According to this configuration, rotary lamination molding can be performed.

The layered 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, the rotation of the plate causes the supply of powder from the supply unit, the measurement of the amount of powder by the measurement unit, the spreading of the powder by the coating unit, and the irradiation of the powder bed with the energy beam. This order can be performed continuously.

The measurement unit of the layered manufacturing apparatus of the present disclosure may be sandwiched between the supply unit and the application unit. According to this configuration, the measuring section can be protected from ambient heat by the supplying section and the applying section. As a result, good measured values can be obtained.

The supply unit, the measurement unit, and the application unit of the layered 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 evenly formed on the disk-shaped plate.

In the layered 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 of the disk-shaped plate. As a result, a radially homogeneous powder bed can be formed.

The layered manufacturing apparatus of the present disclosure may further include a control section that receives a measurement signal from the measurement section and outputs a control signal to the supply section. The control unit may generate a control signal for controlling the amount of powder supplied by the supply unit based on the measurement signal relating to 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 spreading operation.

The powder bed forming apparatus of the present disclosure includes a plate including at least a plate main surface on which powder is placed, and an irradiation unit that irradiates the powder bed, which is the powder spread evenly on the plate main surface, with an energy beam. Forms a powder bed for the modeling device. The powder bed forming apparatus includes a supply unit that supplies powder, and an application unit that spreads the powder supplied from the supply unit over the main surface of the plate by moving relative to the plate in a predetermined direction. and a measuring unit arranged in front of the applying unit in the moving direction of the applying unit with respect to the plate and measuring the amount of powder after being supplied from the supplying unit and before being spread evenly by the applying unit.

The powder bed forming apparatus has a measuring section for measuring the amount of powder in front of the coating section for spreading the powder evenly over the main surface of the plate. According to this configuration, it is possible to measure the amount of powder before it is evenly spread by the application section after being supplied from the supply section. Since it is possible to obtain information about the amount of powder before spreading, it is possible to control the amount of powder supplied from the supply section based on the information. Since a state suitable for even spreading is realized, a desired powder bed can be stably formed by the spreading operation of the application unit. Therefore, the modeling process can be stably continued.

The additive manufacturing apparatus and powder bed forming apparatus of the present disclosure can stably continue the manufacturing process.

FIG. 1 is a schematic diagram showing the configuration of a layered manufacturing apparatus. FIG. 2 is a perspective view showing the main configuration of the layered manufacturing apparatus of FIG. 1. FIG. FIG. 3 is a diagram showing the configuration of the powder supply mechanism. FIG. 4 is a side view of the powder bed forming mechanism. FIG. 5 is a cross-sectional view for explaining coating defects. FIG. 6 is a flowchart showing operations performed by the controller of the layered manufacturing apparatus. FIG. 7 is a cross-sectional view showing the effect of the powder bed forming mechanism. FIG. 8 is a perspective view showing the main configuration of the layered manufacturing apparatus of the first modified example. FIG. 9A is an example of a powder amount measuring device included in the layered manufacturing apparatus of the second modified example. FIG. 9B is an example of a powder amount measuring device included in the layered manufacturing apparatus of the third modification. FIG.9(c) is an illustration of the powder amount measuring device with which the layered manufacturing apparatus of a 4th modification is provided. FIG. 9D is an example of a powder amount measuring device included in the layered manufacturing apparatus of the fifth modified example. FIGS. 9(e) and 9(f) are examples of a powder amount measuring device included in the layered manufacturing apparatus of the sixth modification. FIG. 10 is a side view of a powder bed formation mechanism of a comparative example.

Hereinafter, one form of the layered 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 overlapping descriptions are omitted.

A three-dimensional rotary laminate-molded article manufacturing apparatus (hereinafter referred to as "laminate-molding apparatus 1") shown in FIG. 1 is a so-called 3D printer that manufactures a modeled article PA from powder P1. The layered manufacturing apparatus 1 employs an electron beam as an energy beam. That is, the layered manufacturing apparatus 1 employs a so-called electron gun powder bed melting method.

The powder P1 is a metal powder, such as titanium-based metal powder, Inconel powder, or aluminum powder. Moreover, the powder P1 is not limited to metal powder. The powder P1 may be powder containing carbon fiber and resin, such as CFRP (Carbon Fiber Reinforced Plastics). Also, the powder P1 may be another powder having electrical conductivity. In addition, the powder in the present disclosure is not limited to those having conductivity. For example, when using a laser as the energy beam, the powder P1 does not have to be conductive.

The layered manufacturing apparatus 1 applies energy to the powder P1. In other words, the layered manufacturing apparatus 1 raises the temperature of the powder P1. As a result, powder P1 is melted or sintered. Then, when the additive manufacturing apparatus 1 stops applying energy, the temperature of the powder P1 drops, so that the powder P1 solidifies. That is, the laminate manufacturing apparatus 1 manufactures the modeled article PA by repeating applying and stopping the energy a plurality of times. In the present embodiment, "solidifying the powder P1" means a mode in which the powder P1 that has been liquidized by being heated to a temperature higher than the melting point is solidified, and a mode in which the powder P1 is sintered by being heated to a temperature lower than the melting point. and including. The modeled object PA is, for example, a machine part. The modeled object PA may be another structure.

The layered modeling apparatus 1 has a drive unit 2 , a modeling processing unit 3</b>A, a controller 4 (control section), and a housing 5 . The drive unit 2 realizes various operations required for modeling. The modeling processing unit 3A obtains a modeled article PA by processing the powder P1. Specifically, the processing of the powder P1 includes feeding processing of the powder P1, preheating of the powder P1, and shaping processing of the powder P1. Housing 5 is supported by a plurality of columns. The housing 5 forms a modeling space S. As shown in FIG. The modeling space S is a decompressible airtight space for processing the powder P1 by the modeling processing unit 3 .

In the modeling space S, a start plate 51 and a modeling tank 52 are arranged. The start plate 51 is a processing platform on which modeling processing is performed. The start plate 51 has, for example, a disk shape, and the powder P1, which is the raw material of the modeled object PA, is arranged thereon. The start plate 51 may be arranged such that its central axis overlaps the central axis of the housing 5 . A drive unit 2 is connected to the start plate 51 . The start plate 51 is thus rotated and translated linearly along the axis of rotation by the drive unit 2 .

The drive unit 2 rotates and raises/lowers the start plate 51 . The drive unit 2 has a rotation drive mechanism 21 and an elevation drive mechanism 22 . The rotation drive mechanism 21 rotates the start plate 51 . The upper end of the rotation drive mechanism 21 is connected to the start plate 51 . A lower end of the rotation drive mechanism 21 is attached to a drive source. The elevation drive mechanism 22 raises and lowers the start plate 51 relative to the modeling tank 52 . This elevation is along the rotation axis of the rotary drive mechanism 21 . It should be noted that the drive unit 2 may be any mechanism capable of rotating and raising and lowering the start plate 51, and the drive unit 2 is not limited to the above mechanism.

FIG. 2 shows an enlarged view of the main parts used in the molding process. Forming processing units 3A and 3B are arranged on the start plate 51 . That is, the modeling processing units 3A and 3B face the plate main surface 51a of the start plate 51 . The modeling processing units 3A and 3B are arranged at equal intervals (180 degrees) around the rotation axis. In other words, the modeling processing units 3A and 3B are, for example, equidistantly arranged in the circumferential direction. According to this arrangement, the layer 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 modeling processing units 3A and 3B described above is an example, and is not limited to this configuration. For example, the modeling processing units 3A and 3B may be arranged at different angles in the circumferential direction.

The modeling processing units 3A and 3B differ only in their arrangement positions, and have the same specific components. Note that the components of the modeling processing units 3A and 3B may be different from each other. For example, one of the forming processing units 3A and 3B may be a part of which the other is omitted. The modeling processing unit 3A will be described in detail below.

The modeling processing unit 3A includes a powder bed forming mechanism 30 (powder bed forming section, powder bed forming apparatus), a heater 3a, and a beam source 3b (irradiating section). The powder bed forming mechanism 30 forms a powder bed PB. The heater 3a preheats the powder bed PB. The beam source 3b performs a modeling process of irradiating the powder bed PB with an energy beam.

The powder bed forming mechanism 30 forms the powder bed PB on the start plate 51 . The powder bed forming mechanism 30 has a powder supply mechanism 31 , a powder application 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 evens out 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 being evenly spread by the powder coating mechanism 32 . The powder bed forming mechanism 30 will be described in detail later.

The heater 3a raises the temperature of the powder P1 by radiant heat. As the heater 3a, an infrared heater, for example, may be used, or a gas heater, for example, may be used. The term "preheating" as used herein means a process of heating the powder P1 so that the temperature of the powder P1 in the preheating area is higher than that of the powder P1 in the supply area. Such heat treatment may be, for example, pre-sintering of the powder P1. Preliminary sintering is a state in which the powders P1 are diffused and joined together at the minimum point by a diffusion phenomenon. As an example, the heater 3a heats the powder P1 to a temperature equal to or higher than half of the melting point of the powder P1. This is based on the fact that the sintering diffusion phenomenon is generally active at half or more of the melting point. For example, when the powder P1 is titanium, the preliminary 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 more and 1600° C. or less. Moreover, when the powder P1 is aluminum, the temporary sintering temperature is 300°C. Note that the melting point of aluminum is about 660°C.

A beam source 3b generates an electron beam. The electron beam is applied to 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 between the cathode and anode. The area on the plate main surface 51a irradiated with the electron beam is the area where the temperature of the powder P1 is raised. 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 the temperature (sintering temperature or melting temperature) at which the modeled article PA can be formed. The beam source 3b scans and irradiates a desired portion with an electron beam.

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

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

The controller 4 controls the rotation drive mechanism 21 . As a result, the start plate 51 rotates clockwise CW at a constant rotational speed. This rotational speed may be determined by the temperature rise in the preheating zone and the build zone. 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 that amount of energy to the powder P1 is determined. Then, according to the required time and the length of the trajectory passed when passing through the preheating region, the rotational speed can be obtained. The controller 4 controls the elevation drive mechanism 22 . As a result, the start plate 51 continuously moves downward over time (separation operation). The moving speed of the start plate 51 may be determined by the thickness of the layer (that is, the thickness of the powder bed PB) formed each time the start plate 51 rotates. A controller 4 controls the powder bed forming mechanism 30 . The operation of forming the powder bed PB by controlling the powder bed forming mechanism 30 by the controller 4 will be described later in detail.

The powder bed forming mechanism 30 will be described in detail below. The powder bed forming mechanism 30 has a powder supply mechanism 31 (supply section), a powder application mechanism 32 (application section), and a powder amount measuring device 33 (measurement section).

The powder supply mechanism 31 shown in FIG. 3 conveys the powder P1 by rotating the roller 311 . The powder supply mechanism 31 has rollers 311 , a hopper 312 and a casing 313 . The powder supply mechanism 31 configured by such parts is called a roller feeder. Note that the powder supply mechanism 31 may employ a configuration different from that of the roller feeder. For example, the powder supply mechanism 31 may employ 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 this arrangement of the discharge ports, a quasi-linear uniform supply of the powder P1 can be achieved.

The hopper 312 is a container that contains the powder P1. Hopper 312 supplies powder P1 to casing 313 . The outlet of hopper 312 is connected to the inlet of casing 313 . In addition, in the illustration of FIG. 3, the hopper 312 and the casing 313 form an integrated container. Casing 313 supplies powder P1 provided from hopper 312 to roller 311 . Further, the casing 313 may include a support section that rotatably supports the roller 311 and a drive section that rotates the roller 311 .

The roller 311 is housed inside a casing 313 and has its peripheral surface partly exposed. The roller 311 is rotationally driven by a driving motor, which is a driving unit, and rotates around the rotation axis. A gap G is formed between the peripheral surface 311 a of the roller 311 and the lower end of the casing 313 . The peripheral surface 311a of the roller 311 is preferably rough. The roller 311 has a shape and size (that is, a diameter) capable of maintaining the powder P1 deposited on the peripheral surface 311a. The roller 311 moves the circumferential surface 311a in the circumferential direction as it rotates. The conveying direction in this case is arcuate. The amount of movement of the conveying surface is the amount of movement of the peripheral surface 311 a of the roller 311 and is determined by the radius and rotation angle of the roller 311 . The roller 311 rotates at a predetermined rotation angle under the control of the drive motor by the controller 4 . This rotation inverts the peripheral surface 311a at the front end. At this time, the powder P1 deposited on the peripheral surface 311a with a thickness corresponding to the gap falls from the front end.

In addition, in the powder supply device provided with a roller-type conveying device, the diameter of the roller 311 may be changed in the axial direction. By doing so, it is possible to change the gap G in the radial direction of the start plate 51 . For example, the roller 311 may be configured such that the diameter of the roller 311 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 is greater at the central portion than at the axial ends of the roller 311 . Since the height of the gap G is gradually changed, the powder can be supplied with an appropriate supply amount.

The powder coating mechanism 32 shown in FIG. 4 evenly spreads the powder P1 dropped from the powder supply mechanism 31 onto the plate main surface 51a. Here, "spreading" means forming a layer of the powder P1 having a predetermined thickness on the modeling surface. This layer of powder P1 is called a powder bed PB.

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

A blade tip 321e of the rake blade 321 is separated from the surface PL to be processed by a predetermined height. The surface to be processed PL is, for example, the powder before being supplied with the powder P1 from the powder supply mechanism 31 in the modeling processing unit 3B on the downstream side after being partially irradiated with the energy beam in the modeling processing unit 3A. It means the surface of the floor PB.

When the powder P1 drops onto the surface PL to be processed, the powder P1 is deposited on the surface PL to be processed. The height of the deposited powder P1 is greater than the thickness of the powder bed PB. Then, the front surface 321a of the rake blade 321 is pressed against the deposited powder P1. This pressing is caused by the rotation of the start plate 51 relative to the stationary rake blade 321 . Then, of the deposited powder P1, the powder P1 existing between the surface PL to be processed and the blade tip 321e moves to the rear side of the rake blade 321. As shown in FIG. On the other hand, of 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 cannot move to the blade back side 321b. Accordingly, 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.

In the following description, on the blade front surface 321a side of the rake blade 321, the portion deposited so as to be higher than the surface of the powder bed PB is referred to as "powder pool PD". That is, the powder puddle PD is formed of the powder P1. Since the powder P1 forming the powder pool exists above the blade tip 321e, it cannot move to the blade back surface 321b side. Further, the amount of powder puddle PD is defined as "powder puddle amount". The clump amount may be volume or weight.

Also, the “supply amount” is defined as the volume or weight of the powder P1 supplied from the powder supply mechanism 31 per unit time. Furthermore, 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 is defined as the "powder bed amount". The amount of powder accumulation is determined by the difference between the supply amount and the powder bed amount. For example, if the feed rate is greater than the powder bed rate, the puddle rate will gradually increase. Conversely, if the feed rate is less than the powder bed rate, the puddle rate will gradually decrease. Furthermore, if the feed rate is equal to the powder bed rate, the puddle rate will not increase or decrease.

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

Conversely, assume that the amount of powder accumulation increases with the lapse of time. In this case, coating failure occurs. Poor coating refers to occurrence of non-negligible irregularities on the surface of the powder bed PB. This coating failure will be described in detail.

FIG. 5 is a cross-sectional view showing several layers formed on the start plate 51. As shown in FIG. An unsintered layer P2 made of unsintered powder P1 is formed on the plate main surface 51a. A pre-sintered layer P3 made of pre-sintered powder P1 is formed on the unsintered layer P2. In FIG. 5, the surface of the temporary sintered layer P3 corresponds to the surface PL to be processed. Now, the unsintered powder P1 is supplied from the powder supply mechanism 31 to the surface of the preliminary sintered layer P3, which is the surface PL to be processed. Suppose that the supply amount is larger than the powder bed amount, and the powder accumulation amount is gradually increasing.

As shown in FIG. 5, when the amount of accumulated powder increases, the pressing force acting on the surface PL to be processed due to the accumulated powder PD increases. This pressing force affects the inter-layer frictional force R1 acting between the surface PL to be processed and the contact surface where the puddle PD contacts. Since the pressing force is the normal force, when the pressing force increases, the inter-layer frictional force R1 between the preliminary sintered layer P3 and the powder P1 forming the puddle also increases. In such a state, when the puddle PD receives a pressing force from the rake blade 321 along the traveling direction, a large interlayer frictional force R1 is generated between the preliminary sintered layer P3 and the puddle PD.

On the other hand, a wall frictional force R2 is also generated between the plate main surface 51a and the unsintered layer P2. However, even if the normal force is the same, the state between the preliminary sintered layer P3 and the powder puddle PD and the state between the plate main surface 51a and the unsintered layer P2 are different from each other. Therefore, the magnitude of the interlayer frictional force R1 generated between the temporary sintered layer P3 and the powder puddle PD is different from the magnitude of the wall surface frictional force R2 generated between the plate main surface 51a and the unsintered layer P2. . In the following description, the frictional force generated between the temporary sintered layer P3 and the powder puddle PD is simply referred to as "interlayer frictional force R1". Similarly, the frictional force generated between the plate main surface 51a and the unsintered layer P2 is simply referred to as "wall surface frictional force R2".

First, it is assumed that the interlayer friction force R1 is smaller than the wall surface friction force R2. This assumption holds true when the amount of powder accumulation is small. In this case, when the puddle PD receives a pressing force from the rake blade 321, slippage occurs between the preliminary sintered layer P3 and the puddle PD. At this time, no slip occurs between the plate main surface 51a and the unsintered layer P2. In this case, coating defects do not occur.

Conversely, assume that the magnitude of the interlayer friction force R1 is greater than the wall surface friction force R2. This assumption holds true when the amount of powder accumulation is large. In this case, when the powder puddle PD receives a pressing force from the rake blade 321, the large interlayer frictional force R1 makes it difficult for slippage to occur between the presintered layer P3 and the powder puddle PD. As a result, slippage occurs between the plate main surface 51a and the unsintered layer P2 while no slippage occurs between the temporary sintered layer P3 and the powder puddle PD. In this case, coating failure occurs.

Therefore, the amount of puddle PD (amount of puddle) must be maintained within a predetermined range. The amount of powder accumulation 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 amount of powder supplied from the powder supply mechanism 31 according to the amount of powder accumulation. Since the control of the amount of supply is based on the amount of accumulated powder, it is necessary to measure the amount of accumulated powder. Therefore, the powder bed forming mechanism 30 has a powder amount measuring device 33 for measuring the amount of accumulated powder.

A powder amount measuring device 33 shown in FIG. 4 measures the amount of powder accumulation. The amount of accumulated powder can be treated as the volume of the deposited powder P1, or can be treated as the weight of the deposited powder P1. On the other hand, the powder quantity measuring instrument 33 does not directly measure the volume or weight of the powder P1. The powder amount measuring instrument 33 obtains data on measurement items other than 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 amount measuring instrument 33 may only acquire data related to measurement items other than the volume or weight of the powder P1. In other words, the powder amount measuring instrument 33 does not have to have the function of converting data relating to another measurement item into the volume or weight of the powder P1. In this case, the controller 4 may have the function of converting data relating to another measurement item into the volume or weight of the powder P1.

A measurement item directly measured by the powder amount measuring device 33 is the powder height H or the powder width W. As shown in FIG. The powder amount measuring device 33 measures at least one of the powder height H and the powder width W. In the present disclosure, powder height H is exemplified as a measurement item. A mode in which the powder width W is used as a measurement item will be described as a modified example.

As an example, the powder height H is the distance along the normal direction of the plate main surface 51a from the powder bed surface PBs to the surface of the powder puddle PD (hereinafter referred to as "powder puddle surface PDs"). Any position on the powder P1 positioned in front of the rake blade 321 may be selected as the powder puddle surface PDs. For example, the slope PDs1 formed immediately before the rake blade 321 may be used. Alternatively, it may be a flat surface PDs2 formed further forward of the slope PDs1. In addition, as a reference for the powder height H, a reference other than the powder bed surface PBs may be used. The blade tip 321e 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 puddle surface PDs.

In addition, 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 puddle 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 puddle surface PDs. Further, for example, the plate main surface 51a can be used as a reference for the powder height H. The powder height H in this case is the distance from the plate main surface 51a to the powder pool surface PDs.

A laser rangefinder can be used as an example of the powder amount measuring device 33 . According to the laser rangefinder, the distance from the emission position of the laser L to the surface PDs of the puddle can be obtained. Since the relative position of the powder amount measuring device 33 with respect to the powder coating 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 puddle surface PDs from the distance to the blade tip 321e of the rake blade 321 .

Note that the specific configuration of the powder amount measuring device 33 is not limited to the laser rangefinder. The powder amount measuring instrument 33 may adopt a non-contact method for measuring the powder height H without contacting the powder P1 like a laser rangefinder. The powder amount measuring instrument 33 may employ a contact method that measures the powder height H by contacting the powder P1. Other examples will be described in modified examples to be described later.

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.

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

Next, the controller 4 causes the powder supply mechanism 31 to supply the powder P1 by outputting a control signal (step S2). Further, the controller 4 starts rotating the start plate 51 by outputting a control signal.

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 powder puddle surface PDs. 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 accumulated powder.

Next, the controller 4 compares the amount of accumulated powder, which is the amount of powder before coating, with the set value (step S4). Specifically, the controller 4 determines whether or not the amount of accumulated powder is greater than a set value. As a result of the comparison in step S4, if the amount of accumulated powder is greater than the set value (step S4: YES), the controller 4 outputs a control signal to reduce the supply amount from the powder supply mechanism 31 (step S5 ). As a result of the comparison in step S4, if the amount of accumulated powder is smaller than the set value (step S4: NO), the controller 4 outputs a control signal to increase the amount supplied from the powder supply mechanism 31 (step S6 ).

In addition to the binary control of increasing or decreasing the supply amount, the controller 4 may also perform ternary control of increasing the supply amount, decreasing the supply amount, and maintaining the supply amount.

After that, the powder puddle PD reaches the rake blade 321 due to the rotation of the start plate 51 . As a result, a powder bed PB having a predetermined thickness is formed (step S7).

Next, the controller 4 determines whether or not the modeling process has been completed (step S8). If the modeling process has not been completed (step S8: NO), the process from step S3 is repeated. When the modeling process is completed (step S8: YES), the entire process is terminated.

Hereinafter, the effects of the layered manufacturing apparatus 1 and the powder bed forming mechanism 30 of the present disclosure will be described.

The layered manufacturing apparatus 1 includes a start plate 51 including a plate main surface 51a on which at least the powder P1 is placed, and a powder bed forming mechanism 30 that forms a powder bed PB of the powder P1 evenly spread on the plate main surface 51a. , and 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, and a powder P1 supplied from the powder supply mechanism 31 by moving in the clockwise direction CW relative to the start plate 51. The powder coating mechanism 32 spreads evenly on the main surface 51a, and the powder coating mechanism 32 is arranged in front of the powder coating mechanism 32 in the movement direction of the powder coating mechanism 32 with respect to the start plate 51, and after the powder is supplied from the powder supply mechanism 31, the powder is coated. a powder quantity meter 33 for measuring the quantity of the powder P1 before being evenly spread by the mechanism 32;

The powder bed forming mechanism 30 of the layered manufacturing apparatus 1 has a powder amount measuring device 33 that measures the amount of the powder P1 in front of the powder coating mechanism 32 that evenly spreads the powder P1 on the plate main surface 51a. According to this configuration, it is possible to measure the amount of the powder P1 before being evenly spread by the powder coating mechanism 32 after being supplied from the powder supply mechanism 31 . Since it is possible to obtain information about the amount of the powder P1 before spreading, it is possible to control the amount of the powder P1 supplied from the powder supply mechanism 31 based on the information. Since a state suitable for even spreading is realized, the desired powder bed PB can be stably formed by the spreading operation of the powder applying mechanism 32 . Therefore, the modeling process can be stably continued.

The start plate 51 of the layered manufacturing apparatus 1 may rotate about a predetermined rotation axis, and the rotation of the start plate 51 may cause the powder coating mechanism 32 to move relative to the start plate 51 . According to this configuration, rotary lamination molding can be performed.

In the layered manufacturing apparatus 1, a powder supply mechanism 31, a powder amount measuring device 33, a powder application mechanism 32, and an irradiation unit are arranged in this order from upstream to downstream in the rotation direction of the start plate 51. FIG. According to this configuration, the rotation of the start plate 51 causes the powder supply mechanism 31 to supply the powder P1, the powder amount measuring device 33 to measure the amount of the powder P1, and the powder application mechanism 32 to evenly spread the powder P1. and irradiation of the powder bed PB with the energy beam can be continuously performed in this order.

For example, as in the comparative example shown in FIG. 10, assume that the powder amount measuring device 133 is arranged downstream of the powder coating mechanism 32 . The powder amount measuring device 133 measures the thickness PBt of the powder bed PB. The powder amount measuring instrument 133 is exposed to the modeling space S in its entirety. The modeling space S is a vacuum area. Then, the powder quantity measuring instrument 133 is likely to receive heat radiated as electromagnetic waves from surrounding objects, particularly the powder P1 that has received the electron beam. On the other hand, the powder amount measuring device 33 of the layered 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 application mechanism 32, the exposed surface that receives radiant heat is reduced. In other words, the powder amount measuring device 33 can be protected from ambient heat by the powder supply mechanism 31 and the powder application mechanism 32 . As a result, good measured values can be obtained.

The powder supply mechanism 31 , the powder amount measuring device 33 and the powder coating mechanism 32 of the layered 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 evenly formed on the disk-shaped start plate 51 .

The layered 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 relating to the amount of powder P1 output by the powder amount measuring device 33 . According to this configuration, the powder supply mechanism 31 can supply the powder P1 in an amount suitable for spreading operation.

According to the layered manufacturing apparatus 1 and the powder bed forming mechanism 30, further effects can be obtained. FIG. 7 shows an example of a state in which the amount of puddle has increased. In the example of FIG. 7, it is assumed that although the amount of powder accumulation has increased, no coating failure has occurred. As the amount of accumulated powder increases, the pressing force acting on the rake blade 321 increases. As the pressing force applied to the rake blade 321 increases, the rake blade 321 bends downstream. Since the distance from the blade base end 321f to the blade tip 321e of the rake blade 321 is constant, this bending shortens the length along the normal direction from the blade base end 321f to the blade tip 321e. As a result, the thickness of the powder bed PB increases by the shortened portion (thickness DH). In short, the thickness PDt of the powder bed PB tends to increase as the amount of accumulated powder increases.

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

The layered manufacturing apparatus and 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.

FIG. 8 is a perspective view of a layered manufacturing apparatus 1A of a first modified example. The layered manufacturing apparatus 1A of the first modified example differs from the layered manufacturing apparatus 1 of the embodiment in the configuration of the powder supply mechanism and the powder amount measuring device. Specifically, the layered manufacturing apparatus 1A of the first modified example has a plurality of powder supply mechanisms 31A1, 31A2, and 31A3 arranged along the radial direction of the start plate 51 . Furthermore, the layered manufacturing apparatus 1A of the first modified example has a plurality of powder amount measuring instruments 33A arranged along the radial direction of the start plate 51 . One powder supply mechanism 31A3 corresponds to one powder amount measuring device 33A. According to this configuration, the supply amount can be adjusted for each of the powder supply mechanisms 31A1, 31A2, and 31A3. The amount of powder supplied by the powder supply mechanism 31A1 arranged closest to the center and the supply amount of the powder supply mechanism 31A3 arranged on the outermost side can be made different from each other. For example, in the layered manufacturing apparatus 1A, the amount of powder P1 supplied by the powder supply mechanism 31A1 on the rotation center side of the start plate 51 is less than the amount of powder P1 supplied by the powder supply mechanism 31A3 on the outer peripheral edge side of the start plate 51. can do. Therefore, the powder supply mechanism 31A can supply the amount of the powder P1 corresponding to the radial direction of the disc-shaped start plate 51 . As a result, a radially homogeneous powder bed PB can be formed.

The powder amount measuring device 33 of the powder bed forming mechanism 30 employs a method of measuring the height of the powder using laser light. The technique adopted by the powder quantity measuring instrument 33 is not limited to this technique. The powder amount measuring device 33 of second to sixth modifications will be described below.

FIG. 9(a) shows a powder bed forming mechanism 30B provided in a layered manufacturing apparatus 1B of the second modified example. The powder amount measuring device 33B measures the powder height H. The powder quantity measuring instrument 33B is of a contact type. Specifically, the powder amount measuring instrument 33B has an electric probe 33B1 arranged at a predetermined height. Further, the powder amount measuring instrument 33B has a power supply 33B2 and an ammeter 33B3. Electric probe 33B1, power supply 33B2 and ammeter 33B3 are connected in series. The ammeter 33 B 3 is connected to the rake blade 321 . According to this configuration, the electric probe 33B1, the power source 33B2, the ammeter 33B3 and the rake blade 321 constitute one contact detection circuit. Since electrical probe 33B1 does not directly contact rake blade 321, no current normally flows through the circuit. However, when the amount of puddle increases, the puddle PD contacts the rake blade 321 as well as the electric probe 33B1. Then, the electric probe 33B1 and the rake blade 321 are brought into a conductive state. As a result, current flows in the circuit. Using the flow of this current as a trigger, it is possible to know that the amount of accumulated powder has reached the threshold value.

FIG. 9(b) shows a powder bed forming mechanism 30C provided in a layered modeling apparatus 1C of the third modified example. The powder amount measuring device 33C measures the powder height H. The powder quantity measuring instrument 33C is of a contact type. Specifically, the powder amount measuring instrument 33C has a temperature probe 33C1 and a thermometer 33C2. The temperature probe 33C1 is arranged at the same position as the electric probe 33B1 of the second modified example. When the amount of puddle increases, the puddle PD comes into contact with the temperature probe 33C1. This contact causes a discontinuous change in the temperature data output by the thermometer 33C2. Using this discontinuous change as a trigger, it can be known that the amount of accumulated powder has reached a threshold value.

FIG. 9(c) shows a powder bed forming mechanism 30D provided in a layered manufacturing apparatus 1D of the third modified example. The powder amount measuring device 33D measures the powder width W. Specifically, the powder amount measuring instrument 33D has a foil plate 33D1 and a laser rangefinder 33D2. The foil plate 33D1 is arranged in front of the rake blade 321. As shown in FIG. The foil plate 33D1 may be attached to the housing of the powder coating mechanism 32D. The foil plate 33D1 deforms more easily than the rake blade 321. Also, the tip of the foil plate 33D1 is positioned higher than the blade tip 321e. As the amount of powder accumulation increases, the powder width W becomes longer. As the powder width W becomes longer, the foil plate 33D1 is pressed against the powder P1, so the foil plate 33D1 deforms forward. This deformation is detected by a laser rangefinder 33D2. The powder width W can also be obtained by such a configuration.

FIG. 9(d) shows a powder bed forming mechanism 30E provided in a layered manufacturing apparatus 1E of the fourth modification. The powder amount measuring device 33E measures the powder width W. The powder amount measuring instrument 33E has 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 modified example. The fourth modification differs from the third modification in the configuration for detecting deformation of the foil plate 33E1. In the fourth modification, deformation of the foil plate 33E1 is electrically detected. The contact detection circuit 33E2 includes a contact 33E3, a power supply 33E4, and an ammeter 33E5. When the deformed foil plate 33E1 comes into contact with 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 accumulated powder has reached the threshold value.

FIG.9(e) and FIG.9(f) show the powder bed formation mechanism 30F with which the lamination-modeling apparatus 1F of a 5th modification is provided. The powder amount measuring instrument 33F measures the powder height H or the powder width W. In the fifth modification, the laser detects that the powder width W has reached the threshold. Specifically, the powder amount measuring instrument 33F has 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 radiated from the back side of the paper toward the front side of the paper. When the amount of accumulated powder is small, the laser L is not obstructed 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 accumulated powder is large, the laser L is obstructed by the powder P1, so that it cannot be detected by the light-receiving sensor 33F2 (see FIG. 9(f)). In this light-receiving sensor 33F2, it is possible to know that the amount of accumulated powder has reached the threshold value by using the fact that the detected laser is no longer detected as a trigger.

1, 1A, 1B, 1C, 1D, 1E, 1F Laminated modeling apparatus 2 Drive unit 3 Modeling processing unit 3A Modeling processing unit 3a Heater 3B Modeling processing unit 3b Beam source, beam source (irradiation section)
4 controller (control unit)
5 housing 7 column 21 rotary drive mechanism 22 elevation drive mechanisms 30, 30B, 30C, 30D, 30E, 30F powder bed forming mechanism (powder bed forming section, powder bed forming apparatus)
31, 31A, 31A1, 31A3 powder supply mechanism (supply unit)
32, 32D powder coating mechanism (coating part)
33, 33A, 33B, 33C, 33D, 33E, 33F Powder amount measuring instrument (measurement part)
51 start plate (plate)
51a Plate main surface 52 Modeling tank P1 Powder PA Modeled object PB Powder bed H Powder height W Powder width

Claims (8)

a plate comprising at least a plate main surface on which the powder is placed;
a powder bed forming part that forms a powder bed that is the powder that is evenly spread on the main surface of the plate;
an irradiation unit that irradiates the powder bed with an energy beam,
The powder bed forming part is
a supply unit that supplies the powder;
an application unit that spreads the powder supplied from the supply unit over the main surface of the plate by moving relative to the plate in a predetermined direction;
A measurement unit arranged in front of the application unit in the moving direction of the application unit with respect to the plate and measuring the amount of the powder after being supplied from the supply unit and before being spread evenly by the application unit. and a layered manufacturing apparatus comprising: the plate rotates about a predetermined axis of rotation;
The layered manufacturing apparatus according to claim 1 , wherein rotation of the plate causes relative movement of the applicator with respect to the plate. The layered manufacturing apparatus according to claim 2, wherein 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. The layered manufacturing apparatus according to claim 3, wherein the measurement section is sandwiched between the supply section and the application section. The layered manufacturing apparatus according to claim 4, wherein the supply section, the measurement section, and the application section extend from the rotation axis toward the outer peripheral edge of the plate. The layered manufacturing apparatus according to claim 5, wherein the amount of the powder supplied by the supply unit on the rotation center side of the plate is smaller than the amount of the powder supplied by the supply unit on the outer peripheral edge side of the plate. A control unit that receives a measurement signal from the measurement unit and outputs a control signal to the supply unit,
7. The control unit according to any one of claims 1 to 6, wherein the control unit generates the control signal for controlling the amount of the powder supplied by the supply unit based on the measurement signal relating to the amount of the powder output by the measurement unit. or the layered manufacturing apparatus according to claim 1. The powder for a layered manufacturing apparatus, comprising: a plate including at least a plate main surface on which powder is placed; A powder bed forming apparatus for forming a bed, comprising:
a supply unit that supplies the powder;
an application unit that spreads the powder supplied from the supply unit over the main surface of the plate by moving relative to the plate in a predetermined direction;
A measurement unit arranged in front of the application unit in the moving direction of the application unit with respect to the plate and measuring the amount of the powder after being supplied from the supply unit and before being spread evenly by the application unit. and a powder bed forming apparatus.

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