JP2023039032A - Method and apparatus for three-dimensional manufacturing - Google Patents

Abstract

To provide a method for three-dimensional manufacturing that can ensure that a manufactured object has a desired manufacturing quality.SOLUTION: A method for three-dimensional manufacturing comprises a first preparation step that acquires a moving picture m including an irradiation point of an energy beam by taking pictures on a plate 51 while emitting an energy beam onto the plate 51, according to a beam-irradiation setting including a heat-input setting indicative of an allowable range of a parameter defining a heat input to be given to a powder material P by an energy beam and locus information defining an irradiation position of the energy beam, a second preparation step that acquires a measurement result of the parameter defining the heat input by analyzing the moving picture m, a third preparation step that determines whether or not the measurement result is included in the allowable range, and a manufacturing step that forms a manufactured object PA by irradiating, while uniformly laying a powder material P over the plate 51, the uniformly-laid powder material P with an energy beam.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a three-dimensional modeling method and a three-dimensional modeling apparatus.

Patent Literature 1 discloses an apparatus and method for forming a three-dimensional object by irradiating an electron beam to a powder material spread evenly in a chamber to melt and solidify the powder material.

Japanese Patent No. 6101707

The build quality of a part manufactured by a 3D printer is subject to various influences during the build operation. The modeling quality is affected by, for example, the amount of heat applied per unit volume of the model (hereinafter referred to as "heat input"). For example, if the amount of heat input is small, the powder material will not melt and defects will remain, and if the amount of heat input is large, the powder material will melt down. The heat input depends on the parameters that define the heat input (eg, beam power, velocity, etc.). However, since it is difficult to measure the parameters that determine the amount of heat input during the actual modeling operation, the actual amount of heat input was unknown. As a result, it was not possible to determine whether or not the modeled object had the desired modeled quality.

Accordingly, the present disclosure describes a three-dimensional modeling method and a three-dimensional modeling apparatus that can ensure that a modeled object has desired modeling quality.

A three-dimensional fabrication method according to an aspect of the present disclosure includes a heat input setting that indicates an allowable range of parameters that define a heat input applied to a powder material by an energy beam, and trajectory information that defines the irradiation position of the energy beam. According to the irradiation setting, while irradiating the energy beam toward the plate, the first preparation step of acquiring a moving image containing the irradiation point of the energy beam by photographing the plate and analyzing the moving image, the amount of heat input A second preparation step of acquiring the measurement results of the parameters that define the, a third preparation step of determining whether the measurement results are included in the allowable range, and spreading the powder material on the plate while spreading it evenly and a molding step of molding a three-dimensional object by irradiating the powder material thus obtained with an energy beam.

In this three-dimensional fabrication method, a point irradiated with an energy beam according to a beam irradiation setting including information defining the allowable range of parameters defining the amount of heat input and the movement of the beam is photographed to obtain a moving image. The three-dimensional modeling method analyzes the moving image and acquires the measurement results of the parameters. The three-dimensional modeling method determines whether or not the measurement result is within the allowable range. In this case, it is determined whether the actual parameter measurement result is within the allowable range of the parameter. If the measurement result is within the allowable range, it can be seen that the range of heat input to the three-dimensional structure is within the allowable range. This makes it possible to ensure that the modeled object has the desired modeling quality.

The second preparation step counts the number of frames in which the energy beam is continuously projected by determining whether or not an energy beam irradiation point is included in each frame of the moving image, and counts the number of frames in which the energy beam is projected. The speed at which the irradiation point of the energy beam moves along the trajectory may be obtained as a measurement result based on the length of the trajectory and the frame rate of the moving image. In this case, the speed at which the energy beam is actually applied is acquired as the measurement result. This makes it possible to more precisely ensure that the heat input determined by the speed is within the allowable range. Therefore, it is possible to ensure that the modeled article has the desired modeling quality.

The first preparation step may irradiate the beam so that the trajectory of the energy beam is circular. In this case, even a narrow region on the plate can be irradiated with the energy beam for a longer distance, so that the irradiation trajectory can be determined more accurately. As a result, the measurement results can be made more accurate.

The first preparation step may irradiate the energy beam so that the energy beam moves along the trajectory at a constant speed. In this case, the energy beam appears at a constant speed in the frames of the moving image during the irradiation of the energy beam. As a result, more accurate measurement results can be obtained.

A three-dimensional modeling apparatus according to an aspect of the present disclosure includes a heat input amount setting indicating an allowable range of a parameter that defines a heat input amount applied to a powder material by an energy beam, and trajectory information that defines an irradiation position of the energy beam. An irradiation unit that irradiates an energy beam onto the plate according to the irradiation settings, and an imaging unit that photographs the plate and outputs a video containing the irradiation points of the energy beam, and by analyzing the video, heat input is calculated. and a control unit that acquires the measurement result of the parameter that defines the and determines whether the measurement result is included in the allowable range. The irradiation unit forms a three-dimensional structure by spreading the powder material evenly on the plate and irradiating the spread powder material with an energy beam. With this three-dimensional modeling apparatus, it is possible to ensure that the modeled object has the desired modeling quality for the reasons described above.

The control unit includes a counting unit that counts the number of frames in which the energy beam is continuously projected by determining whether or not an energy beam irradiation point is included in each frame of the moving image, and a counting unit that counts the number of frames in which the energy beam is projected, A velocity calculation unit that acquires, as a measurement result, a velocity at which the irradiation point of the energy beam moves along the trajectory based on the length of the trajectory of the beam and the frame rate of the moving image. Even in this case, for the reasons described above, it is possible to ensure that the object has the desired modeling quality.

The control unit may control the irradiation of the energy beam by the irradiation unit so that the trajectory of the energy beam becomes circular. Even in this case, the measurement results can be made more accurate for the reasons described above.

The control unit may control the irradiation of the energy beam by the irradiation unit so that the energy beam moves along the trajectory at a constant speed. Even in this case, the measurement results can be made more accurate for the reasons described above.

According to the three-dimensional modeling method and the three-dimensional modeling apparatus of the present disclosure, it is possible to ensure that the modeled object has desired modeling quality.

FIG. 1 is a schematic diagram showing the configuration of a three-dimensional modeling apparatus. FIG. 2 is a block diagram showing the main configuration related to parameter measurement. FIG. 3 is a diagram illustrating an example of a hardware configuration of a control unit; FIG. 4 is a diagram showing an example of trajectory information. FIG. 4(a) shows a circular trajectory. FIG. 4(b) shows an intermittent trajectory. FIG. 4(c) shows a trajectory along which acceleration and deceleration are performed. FIG. 5 is a flow chart showing an example of processing of the counting unit. FIG. 6 is a flow chart showing the operation of the 3D modeling apparatus.

Hereinafter, the three-dimensional modeling method and three-dimensional modeling apparatus of the present disclosure will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations are omitted.

The three-dimensional rotary laminate-molded article manufacturing apparatus (hereinafter referred to as "three-dimensional modeling apparatus 1") shown in FIG. The three-dimensional modeling apparatus 1 employs, for example, an electron beam as an energy beam. For example, the three-dimensional modeling apparatus 1 employs a so-called electron gun powder bed melting method.

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

The three-dimensional modeling apparatus 1 applies energy to the powder material P. As shown in FIG. In other words, the three-dimensional modeling apparatus 1 raises the temperature of the powder material P. As a result, the powder material P is melted or sintered. Then, when the three-dimensional modeling apparatus 1 stops applying energy, the temperature of the powder material P drops, so that the powder material P solidifies. That is, the three-dimensional modeling apparatus 1 manufactures the modeled object PA by repeating applying and stopping the energy a plurality of times. In the present disclosure, "solidifying the powder material P" refers to a mode in which the powder material P that is heated to a temperature higher than the melting point and becomes liquid is solidified, and a mode in which the powder material P is heated to a temperature lower than the melting point to sinter. Aspects. The modeled object PA is, for example, a machine part. The modeled object PA may be another structure.

The three-dimensional modeling apparatus 1 has a drive unit 2, a processing unit 3, a control section 4, a housing 5, a window section 6, and a camera 7 (photographing section). The drive unit 2 realizes various operations required for modeling. The processing unit 3 processes the powder material P to obtain a model PA. The processing of the powder material P includes a supply process of the powder material P, a preheating process of the powder material P, and a shaping process of the powder material P. The control unit 4 controls the entire apparatus of the three-dimensional modeling apparatus 1 . 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 material P by the processing unit 3 . The window part 6 is an observation window through which the modeling space S can be visually recognized from the outside of the three-dimensional modeling apparatus 1 . A window 6 is provided in the housing 5 . The camera 7 takes an image on a plate 51 which will be described later.

In the modeling space S, a plate 51 and a modeling tank 52 are arranged. The plate 51 is a processing platform on which modeling processing is performed. The plate 51 is, for example, a circular plate, and the powder material P, which is the raw material of the modeled object PA, is arranged thereon. The plate 51 is arranged so that its central axis overlaps the central axis of the housing 5 . A drive unit 2 is connected to the plate 51 . The plate 51 is thus rotated and translated linearly along the axis of rotation by the drive unit 2 . The modeling tank 52 is a container in which the powder material P is stored. The modeling tank 52 is arranged so as to surround the plate 51 .

The drive unit 2 rotates and raises and lowers the 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 plate 51 . The upper end of the rotation drive mechanism 21 is connected to the 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 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 plate 51, and the drive unit 2 is not limited to the above mechanism.

The processing unit 3 is arranged on the plate 51 . The processing unit 3 faces the plate main surface 51 a of the plate 51 . The processing unit 3 has a feeder 3a, a heater 3b, and a beam source 3c (irradiation section). The feeder 3a feeds the powder material P. As shown in FIG. The heater 3b preheats the powder material P. As shown in FIG. The beam source 3c performs the shaping process of the powder material P. As shown in FIG.

Feeder 3 a supplies powder material P to plate 51 . For example, the feeder 3a has a raw material tank and a leveling section. The raw material tank stores the powder material P and supplies the powder material P to the plate 51 . The smoothing section smoothes the surface of the powder material P on the plate 51 . For example, as the plate 51 rotates, the surface layer of the powder material P on the plate 51 abuts against the leveling portion and is leveled. Note that the three-dimensional modeling apparatus 1 may have a roller section, a rod-like member, a brush section, or the like instead of the leveling section. The feeder 3a forms a supply area on the plate main surface 51a. The feed area is the area where the powder material P is fed to the plate 51 and leveled. The supply region has, for example, a rectangular shape whose longitudinal direction is the diameter direction (radial direction) of the plate 51, but is not limited to this.

The heater 3 b heats the powder material P placed on the plate 51 . The heater 3b raises the temperature of the powder material P by radiant heat. An infrared heater, for example, may be used as the heater 3b. The term "preheating" as used herein means a process of heating the powder material P so that the temperature of the powder material P in the preheating area is higher than that of the powder material P in the supply area. Such heat treatment may be, for example, a process of pre-sintering the powder material P. Preliminary sintering is a state in which the powder materials P are diffused and bonded to each other at the minimum point due to a diffusion phenomenon. The heater 3b heats the powder material P to a temperature equal to or higher than half of the melting point of the powder material P, for example. 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 material P 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 material P is aluminum, the preliminary sintering temperature is 300°C. Note that the melting point of aluminum is about 660°C. The heater 3b forms a preheating area on the plate main surface 51a. A preheating area|region is an area|region which raises the temperature of the powder material P. FIG. The preheating area has, for example, a fan-like shape, but is not limited to this.

For example, the beam source 3c irradiates the powder material P placed on the plate 51 with an electron beam. The beam source 3c is, for example, an electron gun. The electron gun generates an electron beam according to the potential difference between the cathode and anode. The beam source 3c forms a shaping area on the plate main surface 51a. The shaping area is an area where the temperature of the powder material P is raised, which is higher than the temperature in the preheating area. That is, the temperature of the powder material P in the modeling area is the temperature (sintering temperature, melting temperature) at which the modeled article PA can be formed. The beam source 3c irradiates an electron beam onto a desired portion within the modeling area. The shape of the modeling area is, for example, circular, but is not limited to this. The modeling region may or may not match the irradiation range (irradiable range) of the beam source 3c.

The positional relationship among the supply area, preheating area and modeling area corresponds to the positional relationship between the feeder 3a, the heater 3b and the beam source 3c. The supply area, preheating area, and modeling area may be formed in this order along the rotation direction of the plate 51 . The areas occupied by the supply area, the preheating area, and the shaping area may be changed as appropriate.

The control unit 4 controls the operations of the drive unit 2 and the processing unit 3 to form a three-dimensional object. The elevation drive mechanism 22 moves the plate 51 upward. The plate 51 is positioned above the modeling tank 52 . The rotation drive mechanism 21 rotates the plate 51 . The feeder 3a supplies the powder material P to the plate 51 and smoothes the surface layer of the powder material P. As shown in FIG. The powder material P is supplied while rotating with the plate 51 . The heater 3b preheats the powder material P before being irradiated with the electron beam. The powder material P is heated while rotating with the plate 51 . The beam source 3c irradiates the powder material P with an electron beam. As a result, the powder material P is melted or sintered, and the modeled object PA is modeled. The elevation drive mechanism 22 lowers the plate 51 . The plate 51 descends as the modeling of the modeled article PA progresses. The lowering of plate 51 may be synchronized with the rotation of plate 51, but need not be perfectly synchronized. Then, when the modeling of all the layers is completed, the modeling of the modeled object PA is completed.

The control unit 4 also measures a parameter that defines the amount of heat input given to the powder material P by the electron beam. The parameters are, for example, electron beam power, scanning speed, and the like. The scanning speed is the speed at which the irradiation point of the electron beam moves along the trajectory. The amount of heat input is the amount of heat given per unit volume of the modeled article PA, and depends on parameters. FIG. 2 is a block diagram showing the main configuration related to parameter measurement. As shown in FIG. 2, the control unit 4 includes a storage unit 41, a beam control unit 42, an acquisition unit 43, a counting unit 44, a distance calculation unit 45, a speed calculation unit 46, a comparison unit 47, , have The controller 4 is electrically connected to the beam source 3c and the camera 7. FIG.

The storage unit 41 stores heat input settings and beam irradiation settings. The heat input setting is the allowable range of parameters that define the heat input applied to the powder material P by the electron beam. The allowable range is defined by the reference value and the allowable error of the parameter. The permissible range is defined as, for example, scanning speed: 960 [mm/sec], permissible error: ±20 [mm/sec], and the like. The beam irradiation settings include, for example, the output of the electron beam, the scanning speed, and trajectory information that defines the irradiation position of the electron beam. The trajectory information defines, for example, the start point and end point of the irradiation position, the route along which the irradiation position moves, and the like. Details of the trajectory information will be described later.

The beam control unit 42 controls irradiation of the electron beam. The beam controller 42 outputs a control signal φ according to the beam irradiation setting to the beam source 3c. The beam source 3c irradiates an electron beam onto the plate 51 according to the control signal φ. When the parameters are measured, the plate 51 is not rotated and the elevation position is fixed. Moreover, the powder material P is not supplied onto the plate 51 . That is, the beam source 3c irradiates the plate main surface 51a of the plate 51 with an electron beam.

The camera 7 outputs to the controller 4 a moving image m of the plate 51 photographed. The moving image m includes images (frames) on the plate 51 before the start of the electron beam irradiation, during the electron beam irradiation, and after the stop of the electron beam irradiation. The frame rate (the number of frames per second) of the moving image m is not limited, and is, for example, 240 [Frame/sec]. The camera 7 is, for example, a digital camera, a high speed camera, or the like. The camera 7 photographs the plate 51 through the window 6 from the outside of the three-dimensional modeling apparatus 1 .

Acquisition unit 43 acquires moving image m from camera 7 . The moving image m includes irradiation points of the electron beam. The irradiation point is a position on the plate 51 where the electron beam is irradiated.

The counting unit 44 determines whether or not the electron beam irradiation point is included for each frame of the moving image m. When the electron beam is irradiated onto the plate 51, the irradiation point becomes hot and emits light. In the present embodiment, light emission is defined as a state in which there are a predetermined number or more of pixels having luminances higher than a luminance threshold. Light emission appears continuously in the image during the irradiation of the electron beam in the moving image m. A counting unit 44 counts the number of frames in which the electron beam is continuously captured. Details of the processing of the counting unit 44 will be described later.

The distance calculator 45 calculates the scanning length of the electron beam. The scan length is the length of the trajectory of the electron beam. The distance calculator 45 calculates the scan length by image analysis using the moving image m. A known technique may be used to calculate the scanning length by image analysis. Further, the distance calculation unit 45 may acquire a value measured by an external measuring device by inputting the value from the input device 105 . For example, an irradiation mark remaining on the plate 51 after electron beam irradiation may be measured.

The speed calculator 46 calculates the scanning speed based on the number of frames in which the electron beam is projected, the scanning length of the electron beam, and the frame rate of the moving image. The speed calculator 46 obtains the time during which the electron beam is continuously projected from the frame rate and the number of frames counted by the counter 44 . The speed calculator 46 calculates the scanning speed based on the time during which the electron beam is continuously reflected and the scanning length (distance) of the electron beam. The scanning speed is an example of a parameter measurement result.

The comparison unit 47 determines whether the measurement result is within the allowable range. For example, the comparison unit 47 determines whether the scanning speed is within the allowable error. When the allowable range is scanning speed: 960 [mm/sec] and allowable error: ±20 [mm/sec], the comparison unit 47 determines that the measured scanning speed is included in the range of 940 to 980 [mm/sec]. Determine whether or not

The controller 4 is realized by any combination of hardware and/or software. Each function may be realized by two or more physically and/or logically separated devices that are directly and/or indirectly connected to each other.

FIG. 3 is a diagram illustrating an example of a hardware configuration of a control unit; As shown in FIG. 3, the control unit 4 physically includes a processor 101, a memory 102, a storage 103, a communication device 104, an input device 105, an output device 106, a bus 107, and the like. It may be configured as a computer device. Each function in the control unit 4 is performed by loading predetermined software (program) on hardware such as the processor 101 and the memory 102, the processor 101 performs calculations, communication by the communication device 104, or the memory 102 and storage It is realized by controlling reading and writing of data in 103 .

The processor 101, for example, operates an operating system and controls the entire computer. The processor 101 may be configured by a central processing unit (CPU). For example, various processes of the control unit 4 may be implemented by the processor 101 . The processor 101 also reads programs (program codes), software modules, and data from the storage 103 or the communication device 104 to the memory 102, and executes various processes according to them. The function of executing various processes of the control unit 4 may be implemented by a control program stored in the memory 102 and operated by the processor 101 . Various processes in the control unit 4 may be executed by one processor 101, or may be executed by two or more processors 101 simultaneously or sequentially.

The memory 102 is a computer-readable recording medium, and is composed of at least one of, for example, ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), and the like. may be

The storage 103 is a computer-readable recording medium. The storage 103 may comprise at least one of, for example, a hard disk drive, a flexible disk, a magneto-optical disk, and an optical disk such as a CD-ROM (Compact Disc ROM). The storage media described above may be, for example, a database, server, or other suitable media including memory 102 and storage 103 or the like.

The communication device 104 is a device for communicating between computers via wired and/or wireless networks. For example, part of the various processes of the control unit 4 may be implemented by the communication device 104 .

The input device 105 is an input device (for example, a keyboard or the like) that receives input from the outside. The output device 106 is an output device (such as a display) that outputs to the outside.

Each of the above devices are connected by a bus 107 for communicating information. The bus 107 may be composed of a single bus, or may be composed of different buses between devices.

An example of trajectory information will be described with reference to FIG. The trajectory information of the present disclosure needs to satisfy three conditions: that it is a so-called unicursal trajectory, that the scanning speed does not fluctuate during electron beam irradiation, and that it is on the plate 51 and within the imaging field of the camera 7 . There is As long as these conditions are satisfied, the shape of the trajectory does not matter.

The trajectory information T1 shown in FIG. 4(a) satisfies all of the above three conditions. The trajectory information T1 has a route that draws a circle clockwise CW from the start point ST to the end point ED. A diameter D of the circle is, for example, about 200 mm. The center of the circle is on the central axis of the plate 51, for example. The beam source 3c irradiates the plate 51 with an electron beam along the trajectory information T1. When the irradiation point moves along the trajectory information T1, a circular trajectory remains on the plate 51 due to heating. The circular locus has a width W (eg 100 μm) corresponding to the width of the electron beam. Such trajectory information T1 is stored in the storage unit 41 . Note that the trajectory indicated by the trajectory information T1 is not limited to an exact circle. The trajectory indicated by the trajectory information T1 may have any shape as long as the length of the trajectory can be obtained. For example, the trajectory information T1 may have a route that draws an ellipse. Furthermore, when the trajectory information T1 defines a circular trajectory indicated by the diameter D, it is not required that the trajectory actually irradiated with the electron beam matches the set trajectory. The allowable deviation of the actual trajectory from the trajectory indicated by the trajectory information T1 may be set based on the allowable error in determining the heat input amount.

Trajectory information T2 shown in FIG. 4B shows a reference example that does not satisfy the above conditions. A start point ST and an end point ED of the trajectory information T2 are located on the circumference. The start point ST is located on one end side of the straight line LN passing through the center of the circle, and the end point ED is located on the other end side of the straight line LN. The trajectory information T2 has a route T2a that draws an arc clockwise from the starting point ST to the other end of the straight line LN. Further, the trajectory information T2 has a route T2b that passes through the straight line LN and moves from the other end to one end of the straight line LN. Further, the trajectory information T2 has a route T2c that draws an arc counterclockwise from one end of the straight line LN to the end point ED. In the trajectory information T2, the electron beam is non-irradiated when passing on the straight line LN. The trajectory information T2 may have movement paths by a plurality of beam sources 3c. The trajectory information T2 may have, for example, a first path that draws an arc clockwise from the start point ST to the end point ED, and a second path that draws an arc counterclockwise from the start point ST to the end point ED for the second irradiation point. good. Such trajectory information T2 does not satisfy the condition of single-stroke writing, so it does not have to be stored in the storage unit 41 .

Trajectory information T3 shown in FIG. 4C shows a reference example that does not satisfy the above conditions. The trajectory information T3 has a one-stroke path that moves in a substantially rectangular shape. In the trajectory information T3, the first side, the second side, the third side, and the fourth side are defined in order from the start point ST, and each side is divided into two sections (first half section and second half section). The trajectory information T3 indicates a route that decelerates in the second half section A1 of the first side, accelerates in the first half section A2 of the second side, decelerates in the second half section A3, and accelerates in the first half section A4 of the third side. have. Such trajectory information T3 does not have to be stored in the storage unit 41 because the scanning speed fluctuates.

An example of the processing of the counting unit 44 will be described with reference to the flowchart shown in FIG. The counting unit 44 initializes the number of a frame to be processed (hereinafter referred to as "frame No.") and the number F of frames in which the electron beam is continuously captured (step S1). For example, the counting unit 44 may calculate the frame number. is set to 1, and the number of frames F is set to 0. Next, image analysis is performed on the frame to be processed (step S2). The counting unit 44, for example, counts the frame number. 1 image is analyzed to obtain the brightness of each pixel. The counting unit 44 counts the number of pixels having luminance Lu or more, which is a threshold value for luminance.

The counting unit 44 determines whether or not the number of pixels having luminance Lu or more is equal to or more than the threshold value E (step S3). If the number of pixels with luminance Lu or higher is equal to or higher than the threshold value E, it indicates that the frame to be processed is an image during electron beam irradiation. On the other hand, when the number of pixels having luminance Lu or higher is less than the threshold value E, it indicates that the frame to be processed is an image before or after electron beam irradiation.

If the number of pixels with luminance Lu or higher is equal to or higher than the threshold value E (Yes in step S3), the process proceeds to step S4. The counting unit 44 increments the number of frames (step S4). In other words, the counting unit 44 counts up the number of frames by adding 1 to the current number of frames. Subsequently, the counting unit 44 determines the frame number. is incremented (step S5). In other words, the counting unit 44 moves the frame to be processed to the next frame.

If the number of pixels with luminance Lu or more is not equal to or greater than the threshold value E (No in step S3), the process proceeds to step S6. The counting unit 44 determines whether or not the number of frames F is 0 (step S6). When the frame number F is 0, it indicates that the frame to be processed has not yet been irradiated with the electron beam. In this case (Yes in step S6), the process proceeds to step S5. When the number of frames is not 0 (No in step S6), the process ends.

After step S5, the process returns to step S2. By returning to step S2, the frame to be processed is sequentially switched. When all the processes are completed, the counting section 44 outputs the number of frames F. FIG. The number of frames F indicates the number of images during electron beam irradiation.

Next, a three-dimensional modeling method executed by the three-dimensional modeling apparatus 1 will be described with reference to the flowchart shown in FIG. It is assumed that the storage unit 41 stores the heat input setting and the beam irradiation setting in advance. In the following, it is assumed that the permissible range of parameters in setting the amount of heat input is scanning speed: 960 [mm/sec] and permissible error: ±20 [mm/sec].

The 3D modeling apparatus 1 takes an image of the plate 51 as a first preparation step (step S10). The three-dimensional modeling apparatus 1 photographs the plate 51 while irradiating the electron beam onto the plate 51 according to the beam irradiation settings. Then, the three-dimensional modeling apparatus 1 acquires the moving image m including the irradiation point of the electron beam. More specifically, after the camera 7 starts photographing the plate 51, the beam source 3c irradiates the plate 51 with an electron beam. The controller 4 controls the irradiation of the electron beam from the beam source 3c so that the trajectory of the electron beam becomes circular. Further, the controller 4 controls the electron beam irradiation from the beam source 3c so that the scanning speed is constant. If the scanning speed is not constant, the heat input can also vary depending on the scanning speed. In the present disclosure, the scanning speed is assumed to be "constant" as long as unintended fluctuations in the scanning speed do not affect the measurement accuracy. “Constant” is defined as being within the permissible range of the parameter, which is the heat input setting. The controller 4 controls electron beam irradiation so that the scanning speed is within the allowable range. When the electron beam irradiation stops, the camera 7 outputs the moving image m to the controller 4 .

The three-dimensional modeling apparatus 1 analyzes the moving image m frame by frame (step S11). The 3D modeling apparatus 1 obtains the number F of frames in which the electron beam is continuously captured based on the moving image m by the process shown in FIG. 4 .

The three-dimensional modeling apparatus 1 calculates the scan length of the electron beam (step S12). The distance calculator 45 calculates the scanning length using the moving image m. The distance calculator 45 detects the trajectory of the electron beam by, for example, edge detection for the frame after the irradiation of the electron beam, and calculates the length of the trajectory.

The three-dimensional modeling apparatus 1 calculates the scanning speed of the electron beam (step S13). Assuming that the frame rate of the moving image m is c [Frame/sec], the shutter interval of the camera 7 is 1/c [sec]. Assuming that the imaging timing of the camera 7 coincides with the start and stop of electron beam irradiation, the scanning time t can be expressed by the following equation (1) using the number of frames F[Frame].

However, the imaging timing of the camera 7 and at least one of the start and stop of electron beam irradiation are not necessarily synchronized. Therefore, at least one of the start and stop of irradiation, an imaging omission of up to 1/c [sec] may occur. Therefore, the actual scanning time t [sec] satisfies the range of the following formula (2).

Here, assuming that the scanning speed is v and the scanning length is L [mm], the scanning speed v is calculated by scanning length L/scanning time t. From the expressions (1) and (2), the scanning speed v satisfies the range of the following expression (3).

Therefore, by averaging the upper limit value and the lower limit value that can be considered from the measurement results, the measured velocity value represented by the following equation (4) is defined as v _m [mm/sec].

The three-dimensional modeling apparatus 1 acquires the scanning speed v _m as the measurement result of the parameter using Equation (4). The above-described steps S11 to S13 can be regarded as a second preparatory step of obtaining the measurement results of the parameters that define the heat input amount by analyzing the moving image m.

The 3D modeling apparatus 1 evaluates the scanning speed _vm as a third preparatory step (step S14). The comparison unit 47 evaluates the scanning speed v _m by determining whether the measured scanning speed v _m is within the allowable range of 940 to 980 [mm/sec].

When the scanning speed v _m is within the allowable range, it can be said that the heat input actually given to the powder material P is appropriate. Therefore, it can be said that the heat input to the powder material P is appropriately performed in the modeling operation performed immediately before or after measuring the scanning speed _vm . Appropriate heat input means that the quality of the model evaluated based on the heat input satisfies the criteria.

As a modeling process, the three-dimensional modeling apparatus 1 forms the object PA by spreading the powder material P evenly on the plate 51 and irradiating the spread powder material P with an electron beam (step S15).

In the three-dimensional fabrication method, according to the beam irradiation setting including the heat input setting indicating the allowable range of the parameter that defines the heat input given to the powder material P by the electron beam and the trajectory information defining the irradiation position of the electron beam, the plate 51 While irradiating the electron beam upward, the heat input is defined by the first preparation step of capturing a moving image m containing the irradiation point of the electron beam by photographing the plate 51 and analyzing the moving image m. a second preparation step of acquiring the measurement results of the parameters to be measured; a third preparation step of determining whether the measurement results are within the allowable range; and a molding step of molding the object PA by irradiating the powdered material P with an electron beam.

In this three-dimensional fabrication method, a moving image m is acquired by photographing points irradiated with an electron beam according to beam irradiation settings including information defining the allowable range of parameters that define the amount of heat input and the movement of the beam. In the three-dimensional modeling method, the moving image m is analyzed to acquire parameter measurement results. The three-dimensional modeling method determines whether or not the measurement result is within the allowable range. In this case, it is determined whether the actual parameter measurement result is within the allowable range of the parameter. If the measurement result is within the allowable range, it can be seen that the range of the amount of heat input to the modeled article PA is within the allowable range. This makes it possible to ensure that the modeled article PA has the desired modeling quality.

In the second preparation step, the number F of frames in which the electron beam is continuously projected is counted by judging whether or not the irradiation point of the electron beam is included in each frame of the moving image m, and the number of frames F in which the electron beam is projected is counted. , the length of the trajectory of the electron beam, and the frame rate of the moving image m, the speed at which the irradiation point of the electron beam moves along the trajectory is obtained as a measurement result. In this case, the velocity at which the electron beam is actually irradiated is acquired as the measurement result. This makes it possible to more precisely ensure that the heat input determined by the speed is within the allowable range. Therefore, it is possible to ensure that the modeled article PA has desired modeling quality.

In the first preparation step, the beam is irradiated so that the trajectory of the electron beam becomes circular. In this case, even a narrow area on the plate 51 is irradiated with the electron beam for a longer distance, so that the irradiation trajectory can be determined more accurately. As a result, the measurement results can be made more accurate.

In the first preparation step, the electron beam is irradiated so that the electron beam moves along the trajectory at a constant speed. In this case, the electron beam appears at a constant speed in the frames of the moving image m during the irradiation of the electron beam. As a result, more accurate measurement results can be obtained.

By the way, the additive manufacturing technology is a relatively new manufacturing technology. A modeled article PA obtained by layered manufacturing is required not only to have a desired shape, but also to have mechanical properties such as strength. However, a method for evaluating whether the modeled article PA manufactured by the layered manufacturing technique has desired quality has not yet been established. A parameter that affects the quality of the modeled article PA is the amount of heat input. If the amount of heat input is too large or too small, defects or the like will occur inside the modeled article PA. Therefore, if it can be confirmed that the heat input is properly managed, at least it can be proved that there are no defects caused by inadequate heat input. Therefore, the inventors diligently studied a technique that can measure the heat input of the modeled article PA with high accuracy to the extent that it can be applied to quality control, and as a result, came up with the three-dimensional modeling method and the three-dimensional modeling apparatus 1 of the present disclosure. reached.

The three-dimensional modeling apparatus 1 uses a heat input setting that indicates the allowable range of a parameter that defines the heat input applied to the powder material P by the electron beam, and a beam irradiation setting that includes trajectory information that defines the irradiation position of the electron beam. A beam source 3c that irradiates an electron beam toward the top of 51, a camera 7 that photographs the plate 51 and outputs a moving image m containing the irradiation point of the electron beam, and by analyzing the moving image m, the amount of heat input and a control unit 4 that acquires the measurement result of the parameter that defines and determines whether the measurement result is included in the allowable range. The beam source 3c forms the object PA by spreading the powder material P evenly on the plate 51 and irradiating the spread powder material P with an electron beam. For the reasons described above, the three-dimensional modeling apparatus 1 can ensure that the modeled object PA has desired modeling quality.

The control unit 4 includes a counting unit 44 that counts the number of frames F in which the electron beam is continuously projected by determining whether or not the electron beam irradiation point is included in each frame of the moving image m, and a counting unit 44 that counts the number of frames F in which the electron beam is projected. A speed calculation unit 46 that acquires the speed at which the irradiation point of the electron beam moves along the trajectory as a measurement result based on the number of frames F, the length of the trajectory of the electron beam, and the frame rate of the moving image m. Even in this case, for the reason described above, it is possible to ensure that the modeled object PA has the desired modeling quality.

The controller 4 controls the irradiation of the electron beam from the beam source 3c so that the trajectory of the electron beam becomes circular. Even in this case, the measurement results can be made more accurate for the reasons described above.

The controller 4 controls the irradiation of the electron beam from the beam source 3c so that the electron beam moves along the trajectory at a constant speed. Even in this case, the measurement results can be made more accurate for the reasons described above.

The three-dimensional modeling method and three-dimensional modeling 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.

In the embodiment, an example of obtaining the scanning speed as the measurement result has been described, but the measurement result may be the scanning length, the output of the electron beam, or the like. In addition, the three-dimensional modeling method may perform the process of step S15 before step S10. Even in these cases, if the measurement result is within the allowable range, it can be seen that the range of the amount of heat input to the modeled object PA is within the allowable range. This makes it possible to ensure that the modeled article PA has the desired modeling quality.

In the three-dimensional modeling method, the first measurement result may be acquired by the processes of steps S10 to S14, and after the process of step S15, the processes of steps S10 to S14 may be further executed to acquire the second measurement result. In this case, when the first measurement result and the second measurement result are within a predetermined range, it can be evaluated that the parameter measurement result is stable in the modeling step (step S15).

The camera 7 may output an image of the plate 51 photographed to the control unit 4 in addition to the moving image m. For example, the camera 7 may output to the control unit 4 an image of the plate 51 after the electron beam irradiation has stopped in order to calculate the scan length. The camera 7 may be provided inside the three-dimensional modeling apparatus 1 . The plate 51 may be rotating during parameter measurement, and the powder material P may be placed on the plate 51 . Even in these cases, it is possible to ensure that the modeled article PA has the desired modeling quality for the reasons described above.

1 Three-dimensional modeling apparatus 2 Drive unit 3 Processing unit 3a Feeder 3b Heater 3c Beam source 4 Control part 5 Housing 6 Window part 7 Camera 21 Rotation drive mechanism 22 Elevation drive mechanism 41 Storage part 42 Beam control part 43 Acquisition part 44 Counting part 45 distance calculation unit 46 speed calculation unit 47 comparison unit 51 plate 51a plate main surface 52 modeling tank 101 processor 102 memory 103 storage 104 communication device 105 input device 106 output device 107 bus φ control signal m moving image P powder material PA modeled object S modeling space

Claims (8)

The energy beam is directed onto a plate according to a beam irradiation setting including a heat input setting indicating an allowable range of parameters defining the heat input applied to the powder material by the energy beam and trajectory information defining the irradiation position of the energy beam. a first preparation step of acquiring a moving image including the irradiation point of the energy beam by photographing the plate while irradiating the
A second preparation step of acquiring measurement results of parameters that define the heat input by analyzing the moving image;
a third preparation step of determining whether the measurement result is included in the allowable range;
A modeling step of spreading the powder material evenly on the plate and irradiating the evenly spread powder material with the energy beam to form a three-dimensional model;
A three-dimensional modeling method comprising: The second preparation step includes
counting the number of frames in which the energy beam is continuously projected by determining whether or not each frame of the moving image includes an irradiation point of the energy beam;
The speed at which the irradiation point of the energy beam moves along the trajectory is measured based on the number of frames in which the irradiation point of the energy beam moves, the length of the trajectory of the energy beam, and the frame rate of the moving image. The three-dimensional fabrication method according to claim 1, obtained as a result. 3. The three-dimensional fabrication method according to claim 1, wherein said first preparation step irradiates said beam so that said trajectory of said energy beam is circular. The three-dimensional fabrication method according to any one of claims 1 to 3, wherein said first preparation step irradiates said energy beam so that said energy beam moves at a constant speed along said trajectory. The energy beam is directed onto a plate according to a beam irradiation setting including a heat input setting indicating an allowable range of parameters defining the heat input applied to the powder material by the energy beam and trajectory information defining the irradiation position of the energy beam. an irradiation unit that irradiates the
a photographing unit for photographing the plate and outputting a moving image including the irradiation point of the energy beam;
A control unit that acquires a measurement result of a parameter that defines the heat input amount by analyzing the moving image and determines whether the measurement result is included in the allowable range,
The irradiation unit forms a three-dimensional modeled object by spreading the powder material evenly on the plate and irradiating the evenly spread powder material with the energy beam. The control unit
a counting unit that counts the number of frames in which the energy beam is continuously displayed by determining whether or not the energy beam irradiation point is included in each frame of the moving image;
Based on the number of frames in which the energy beam is projected, the length of the trajectory of the energy beam, and the frame rate of the moving image, the speed at which the irradiation point of the energy beam moves along the trajectory is obtained as the measurement result. and a speed calculation unit that
The three-dimensional modeling apparatus according to claim 5. 7. The three-dimensional modeling apparatus according to claim 5, wherein said control unit controls irradiation of said energy beam by said irradiation unit so that said trajectory of said energy beam becomes circular. 8. The controller according to any one of claims 5 to 7, wherein said control unit controls irradiation of said energy beam by said irradiation unit so that the speed of movement of said energy beam along said trajectory is constant. Three-dimensional modeling device.

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