Three-dimensional modeling method and three-dimensional modeling device

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

[Technical Field]

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

[0002] Patent Document 1 discloses an apparatus and method for irradiating powder material spread evenly in a chamber with an electron beam to melt and solidify the powder material, thereby forming a three-dimensional object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6101707 Summary of the Invention [Problem to be solved by the invention]

[0004] The build quality of parts manufactured by a 3D printing device is affected by various factors during the printing operation. For example, build quality is affected by the amount of heat applied per unit volume of the object to be printed (hereinafter referred to as "heat input"). For example, if the heat input is too low, the powder material will not melt, leaving defects, while if the heat input is too high, the powder material will melt away. The heat input depends on parameters that determine the heat input (e.g., beam output, speed, etc.). However, because it is difficult to measure the parameters that determine the heat input during actual printing operations, the actual heat input amount was unknown. As a result, it was not possible to determine whether the object had the desired build quality.

[0005] Therefore, the present disclosure describes a three-dimensional printing method and a three-dimensional printing apparatus that can ensure that a modeled object has a desired modeling quality. [Means for solving the problem]

[0006] A three-dimensional printing method according to one embodiment of the present disclosure includes a first preparatory step of photographing the plate to obtain a video including the irradiation point of the energy beam while irradiating the plate with an energy beam in accordance with a heat input setting indicating an acceptable range of a parameter that determines the heat input amount imparted to a powder material by the energy beam and a beam irradiation setting including trajectory information that determines the irradiation position of the energy beam; a second preparatory step of analyzing the video to obtain measurement results of the parameter that determines the heat input amount; a third preparatory step of determining whether the measurement results are within the acceptable range; and a printing step of spreading the powder material evenly on the plate and irradiating the spread powder material with the energy beam to form a three-dimensional object.

[0007] This three-dimensional printing method captures a video of a point irradiated with an energy beam according to beam irradiation settings, which include information specifying the allowable range of parameters that define the amount of heat input and the movement of the beam. The three-dimensional printing method analyzes the video to obtain measurement results of the parameters. The three-dimensional printing method determines whether the measurement results are within the allowable range. In this case, it is determined whether the measurement results of the actual parameters are within the allowable range of the parameters. If the measurement results are within the allowable range, it is determined that the range of the amount of heat input to the three-dimensional printed object is within the allowable range. This makes it possible to ensure that the printed object has the desired printing quality.

[0008] The second preparation step may involve counting the number of consecutive frames in which the energy beam appears by determining whether each frame of the video contains an irradiation point of the energy beam, and acquiring the speed at which the irradiation point of the energy beam moves along the trajectory as a measurement result based on the number of frames in which the energy beam appears, the length of the trajectory of the energy beam, and the frame rate of the video. In this case, the actual speed at which the energy beam is irradiated is acquired as the measurement result. This makes it possible to more precisely ensure that the heat input, which is determined by the speed, is within an allowable range. Therefore, it becomes possible to ensure that the molded object has the desired molding quality.

[0009] In the first preparation step, the energy beam may be irradiated so that the trajectory of the energy beam is circular. In this case, even in a narrow area on the plate, the distance irradiated with the energy beam becomes long, so that the irradiation trajectory can be determined more accurately. As a result, the measurement results can be more accurate.

[0010] The first preparation step may involve irradiating the energy beam so that the speed at which the energy beam moves along the trajectory is constant. In this case, the energy beam appears in the video frames at a constant speed during irradiation. As a result, more accurate measurement results can be obtained.

[0011] A three-dimensional printing apparatus according to one aspect of the present disclosure includes an irradiation unit that irradiates an energy beam onto a plate in accordance with a heat input setting indicating an allowable range of a parameter that determines the amount of heat input imparted to a powder material by the energy beam and a beam irradiation setting including trajectory information that determines the irradiation position of the energy beam; an imaging unit that images the plate and outputs a video including the energy beam irradiation point; and a control unit that analyzes the video to obtain measurement results of the parameter that determines the amount of heat input and determines whether the measurement results fall within the allowable range. The irradiation unit spreads the powder material evenly on the plate and irradiates the spread powder material with the energy beam to form a three-dimensional object. For the reasons described above, this three-dimensional printing apparatus can ensure that the object has the desired printing quality.

[0012] The control unit may include a counting unit that counts the number of frames in which the energy beam is continuously captured by determining whether or not the energy beam irradiation point is included in each frame of the video, and a speed calculation unit that acquires, as a measurement result, the speed at which the energy beam irradiation point moves along the trajectory, based on the number of frames in which the energy beam is captured, the length of the trajectory of the energy beam, and the frame rate of the video. Even in this case, it is possible to ensure that the object has the desired printing quality for the reasons described above.

[0013] 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, for the reasons described above, the measurement results can be made more accurate.

[0014] The control unit may control the irradiation of the energy beam by the irradiation unit so that the speed at which the energy beam moves along the trajectory is constant. Even in this case, the measurement results can be made more accurate for the reasons described above. [Effects of the Invention]

[0015] According to the three-dimensional printing method and three-dimensional printing apparatus of the present disclosure, it is possible to ensure that the object has the desired printing quality. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a three-dimensional modeling apparatus. [Figure 2] FIG. 2 is a block diagram showing the main configuration related to parameter measurement. [Figure 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of the control unit. [Figure 4] 4A and 4B are diagrams showing examples of trajectory information. Fig. 4A shows a circular trajectory. Fig. 4B shows an intermittent trajectory. Fig. 4C shows a trajectory in which acceleration and deceleration are performed. [Figure 5] FIG. 5 is a flowchart illustrating an example of the process of the counting unit. [Figure 6] FIG. 6 is a flowchart showing the operation of the three-dimensional modeling apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a three-dimensional modeling method and a three-dimensional modeling apparatus according to the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be omitted.

[0018] The three-dimensional rotational additive manufacturing apparatus (hereinafter referred to as "three-dimensional modeling apparatus 1") shown in FIG. 1 is a so-called 3D printer that manufactures a model PA (three-dimensional model) from powder material P. 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 fusion method.

[0019] The powder material P is a metal powder, such as titanium-based metal powder, Inconel powder, or aluminum powder. The powder material P is not limited to a metal powder. The powder material P may be a powder containing carbon fiber and resin, such as CFRP (Carbon Fiber Reinforced Plastics). The powder material P may also be other conductive powders. The powders in the present disclosure are not limited to those that are conductive. For example, when a laser is used as the energy beam, the powder material P does not need to be conductive.

[0020] The three-dimensional printing apparatus 1 applies energy to the powder material P. In other words, the three-dimensional printing apparatus 1 increases the temperature of the powder material P. As a result, the powder material P melts or sinters. When the three-dimensional printing apparatus 1 stops applying energy, the temperature of the powder material P drops, causing it to solidify. In other words, the three-dimensional printing apparatus 1 produces a model PA by repeatedly applying and stopping energy application multiple times. Note that, in this disclosure, "solidifying the powder material P" includes a case in which the powder material P, which has been heated to a temperature higher than its melting point and has become liquid, solidifies, and a case in which the powder material P is heated to a temperature lower than its melting point and sinters. The model PA is, for example, a mechanical part. The model PA may also be another structure.

[0021] The three-dimensional printing apparatus 1 has a drive unit 2, a processing unit 3, a control unit 4, a housing 5, a window unit 6, and a camera 7 (photographing unit). The drive unit 2 performs various operations required for printing. The processing unit 3 processes a powder material P to obtain a printed object 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 printing process of the powder material P. The control unit 4 controls the entire three-dimensional printing apparatus 1. The housing 5 is supported by multiple columns. The housing 5 forms a printing space S. The printing space S is an airtight space that can be decompressed to process the powder material P by the processing unit 3. The window unit 6 is a viewing window that allows the printing space S to be viewed from outside the three-dimensional printing apparatus 1. The window unit 6 is provided in the housing 5. The camera 7 photographs the top of a plate 51, which will be described later.

[0022] A plate 51 and a modeling tank 52 are arranged in the modeling space S. The plate 51 is a processing stage on which the modeling process is performed. The plate 51 is, for example, a circular plate, and powder material P, which is the raw material of the model PA, is arranged on the plate 51. The plate 51 is arranged so that its central axis overlaps with the central axis of the housing 5. A drive unit 2 is connected to the plate 51. Therefore, the plate 51 rotates and moves linearly along the rotation axis by the drive unit 2. The modeling tank 52 is a container that contains the powder material P. The modeling tank 52 is arranged to surround the plate 51.

[0023] The drive unit 2 rotates and elevates 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. The lower end of the rotation drive mechanism 21 is attached to a drive source. The elevation drive mechanism 22 elevates and lowers the plate 51 relative to the modeling tank 52. This elevation is along the rotation axis of the rotation drive mechanism 21. Note that the drive unit 2 may be any mechanism that can rotate and elevate the plate 51, and the drive unit 2 is not limited to the above mechanism.

[0024] The processing unit 3 is disposed on the plate 51. The processing unit 3 faces the plate main surface 51a of the plate 51. The processing unit 3 has a feeder 3a, a heater 3b, and a beam source 3c (irradiation unit). The feeder 3a performs a supply process of the powder material P. The heater 3b performs a preheat process of the powder material P. The beam source 3c performs a modeling process of the powder material P.

[0025] The feeder 3a supplies the powder material P to the plate 51. For example, the feeder 3a has a raw material tank and a leveling unit. The raw material tank stores the powder material P and supplies the powder material P to the plate 51. The leveling unit levels the surface of the powder material P on the plate 51. For example, the surface layer of the powder material P on the plate 51 comes into contact with the leveling unit as the plate 51 rotates and is spread and leveled. Note that the three-dimensional modeling apparatus 1 may have a roller unit, a rod-shaped member, a brush unit, or the like instead of the leveling unit. The feeder 3a forms a supply region on the plate main surface 51a. The supply region is an area where the powder material P is supplied to the plate 51 and leveled. The supply region has, for example, a rectangular shape with the longitudinal direction aligned with the diameter direction (radial direction) of the plate 51, but is not limited to this.

[0026] The heater 3b heats the powder material P placed on the plate 51. The heater 3b raises the temperature of the powder material P by radiating heat. For example, an infrared heater may be used as the heater 3b. Preheating here refers to a process of heating the powder material P so that its temperature in the preheating area is higher than that of the powder material P in the supply area. This heating process may also be, for example, a process of pre-sintering the powder material P. Pre-sintering is a state in which the powder material P diffuses and bonds at its minimum point due to the diffusion phenomenon. For example, the heater 3b heats the powder material P to a temperature equal to or higher than half the melting point of the powder material P. This is because the diffusion phenomenon of sintering generally becomes active at a temperature equal to or higher than half the melting point. For example, if the powder material P is titanium, the pre-sintering temperature is 700°C to 800°C. The melting point of titanium alloys is approximately 1500°C to 1600°C. If the powder material P is aluminum, the pre-sintering temperature is 300°C. The melting point of aluminum is approximately 660°C. The heater 3b forms a preheating region on the plate main surface 51a. The preheating region is a region where the temperature of the powder material P is increased. The preheating region has, for example, a fan-like shape, but is not limited to this.

[0027] For example, the beam source 3c irradiates an electron beam onto the powder material P placed on the plate 51. The beam source 3c is, for example, an electron gun. The electron gun generates an electron beam according to the potential difference generated between the cathode and the anode. The beam source 3c forms a shaping region on the plate main surface 51a. The shaping region is a region where the temperature of the powder material P is increased, and this temperature is higher than the temperature in the preheating region. In other words, the temperature of the powder material P in the shaping region is a temperature (sintering temperature, melting temperature) at which a shaped object PA can be formed. The beam source 3c irradiates a desired portion within the shaping region with an electron beam. The shape of the shaping region is, for example, circular, but is not limited to this. The shaping region may or may not coincide with the irradiation range (irradiation range) of the beam source 3c.

[0028] The positional relationship between the supply area, preheating area, and building area corresponds to the positional relationship between the feeder 3a, heater 3b, and beam source 3c. The supply area, preheating area, and building area may be formed in this order along the rotation direction of the plate 51. The areas occupied by the supply area, preheating area, and building area may be changed as appropriate.

[0029] The control unit 4 controls the operation of the drive unit 2 and the processing unit 3 to form a three-dimensional object. The lifting drive mechanism 22 moves the plate 51 upward. The plate 51 is positioned at an upper position of the modeling tank 52. The rotation drive mechanism 21 rotates the plate 51. The feeder 3a supplies powder material P to the plate 51 and levels the surface layer of the powder material P. The powder material P is supplied while rotating together with the plate 51. The heater 3b preheats the powder material P before it is irradiated with the electron beam. The powder material P is heated while rotating together with the plate 51. The beam source 3c irradiates the powder material P with the electron beam. This melts or sinters the powder material P, and the model PA is formed. The lifting drive mechanism 22 lowers the plate 51. The plate 51 descends as the modeling of the model PA progresses. The descent of the plate 51 may be synchronized with the rotation of the plate 51, but does not have to be completely synchronized. Then, when the modeling of all layers is completed, the modeling of the object PA is completed.

[0030] The control unit 4 also measures parameters that define the amount of heat input imparted to the powder material P by the electron beam. The parameters include, for example, the output power and scanning speed of the electron beam. 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 imparted per unit volume of the molded object PA and depends on the parameters. Figure 2 is a block diagram showing the main components involved in measuring the parameters. As shown in Figure 2, the control unit 4 includes a memory 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, and a comparison unit 47. The control unit 4 is electrically connected to the beam source 3c and the camera 7.

[0031] The memory unit 41 stores heat input settings and beam irradiation settings. The heat input setting is the allowable range of a parameter that defines the amount of heat input provided to the powder material P by the electron beam. The allowable range is defined by the reference value and allowable error of the parameter. The allowable range is defined, for example, as a scanning speed of 960 [mm / sec] and an allowable error of ±20 [mm / sec]. 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 and the path along which the irradiation position moves. Details of the trajectory information will be described later.

[0032] The beam control unit 42 controls the irradiation of the electron beam. The beam control unit 42 outputs a control signal φ according to the beam irradiation setting to the beam source 3c. The beam source 3c irradiates the electron beam onto the plate 51 in accordance with the control signal φ. When measuring the parameters, the plate 51 is not rotating, and its elevation position is fixed. Furthermore, no powder material P is supplied onto the plate 51. That is, the beam source 3c irradiates the electron beam onto the plate main surface 51a of the plate 51.

[0033] The camera 7 outputs a moving image m of the plate 51 to the control unit 4. The moving image m includes images (frames) of the plate 51 at each of the following times: before the electron beam irradiation starts, while the electron beam is being irradiated, and after the electron beam irradiation stops. The frame rate (number of frames per second) of the moving image m is not limited and is, for example, 240 [frames / sec]. The camera 7 is, for example, a digital camera, a high-speed camera, etc. The camera 7 photographs the plate 51 from outside the 3D printing apparatus 1 through the window 6.

[0034] The acquisition unit 43 acquires a moving image m from the camera 7. The moving image m includes an irradiation point of the electron beam. The irradiation point is a position on the plate 51 where the electron beam is irradiated.

[0035] The counting unit 44 determines whether or not the moving image m includes an irradiation point of the electron beam for each frame. When the electron beam is irradiated onto the plate 51, the irradiation point becomes hot and emits light. In this embodiment, light emission is described as a state in which there are a predetermined number or more pixels with a brightness higher than a brightness threshold. In the moving image m, light emission appears continuously in images while the electron beam is being irradiated. The counting unit 44 counts the number of frames in which the electron beam is continuously displayed. Details of the processing by the counting unit 44 will be described later.

[0036] The distance calculation unit 45 calculates the scanning length of the electron beam. The scanning length is the length of the trajectory of the electron beam. The distance calculation unit 45 calculates the scanning length by image analysis using the moving image m. The calculation of the scanning length by image analysis may be performed using a known technique. The distance calculation unit 45 may also acquire values ​​measured by an external measuring device by inputting the values ​​from the input device 105. For example, the distance calculation unit 45 may actually measure the irradiation marks remaining on the plate 51 after irradiation with the electron beam.

[0037] The speed calculation unit 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 video. The speed calculation unit 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 calculation unit 46 calculates the scanning speed from the time during which the electron beam is continuously projected and the scanning length (distance) of the electron beam. The scanning speed is an example of a measurement result of a parameter.

[0038] The comparison unit 47 determines whether the measurement result is within an allowable range. For example, the comparison unit 47 determines whether the scanning speed is within an allowable error. If the allowable range is a scanning speed of 960 [mm / sec] and an allowable error of ±20 [mm / sec], the comparison unit 47 determines whether the measured scanning speed is within the range of 940 to 980 [mm / sec].

[0039] The control unit 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.

[0040] 3 is a diagram showing an example of the hardware configuration of the control unit. As shown in Fig. 3, the control unit 4 may be physically configured as a computer device including a processor 101, a memory 102, a storage 103, a communication device 104, an input device 105, an output device 106, a bus 107, etc. Each function of the control unit 4 is realized by loading predetermined software (programs) onto hardware such as the processor 101, memory 102, etc., causing the processor 101 to perform calculations and control communication by the communication device 104 or reading and writing of data from and to the memory 102 and storage 103.

[0041] The processor 101 controls the entire computer by running an operating system, for example. 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 reads programs (program codes), software modules, and data from the storage 103 or the communication device 104 into the memory 102 and executes various processes in accordance with these. The function of executing various processes of the control unit 4 may be implemented by a control program stored in the memory 102 and executed by the processor 101. The various processes of the control unit 4 may be executed by one processor 101, or may be executed simultaneously or sequentially by two or more processors 101.

[0042] The memory 102 is a computer-readable recording medium and may be composed of, for example, at least one of a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), a RAM (Random Access Memory), etc.

[0043] The storage 103 is a computer-readable recording medium. The storage 103 may be configured with at least one of a hard disk drive, a flexible disk, a magneto-optical disk, an optical disk such as a CD-ROM (Compact Disc ROM), etc. The storage medium may be, for example, a database including the memory 102 and the storage 103, a server, or other appropriate medium.

[0044] The communication device 104 is a device for communicating between computers via a wired and / or wireless network. For example, some of the various processes of the control unit 4 may be realized by the communication device 104.

[0045] The input device 105 is an input device (for example, a keyboard) that receives input from the outside. The output device 106 is an output device (for example, a display) that outputs to the outside.

[0046] The above devices are connected by a bus 107 for communicating information. The bus 107 may be configured as a single bus or may be configured as different buses between the devices.

[0047] An example of the trajectory information will be described with reference to Fig. 4. The trajectory information of the present disclosure must satisfy three conditions: it must be a so-called one-stroke trajectory, the scanning speed must not fluctuate during irradiation of the electron beam, and it must be on the plate 51 and within the field of view of the camera 7. As long as these conditions are satisfied, the shape of the trajectory does not matter.

[0048] The trajectory information T1 shown in FIG. 4(a) satisfies all three of the above-mentioned conditions. The trajectory information T1 has a path that draws a circle clockwise (CW) from the starting point ST to the end point ED. The diameter D of the circle is, for example, approximately 200 mm. The center of the circle is, for example, on the central axis of the plate 51. The beam source 3c irradiates the plate 51 with an electron beam according to the trajectory information T1. As the irradiation point moves along the trajectory information T1, a circular trajectory is left on the plate 51 due to heating. The circular trajectory has a width W (for example, 100 μm) corresponding to the width of the electron beam. Such trajectory information T1 is stored in the memory 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 that allows the length of the trajectory to be obtained. For example, the trajectory information T1 may have a path 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 completely 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 amount of heat input.

[0049] The trajectory information T2 shown in FIG. 4(b) is a reference example that does not satisfy the above-mentioned conditions. The start point ST and end point ED of the trajectory information T2 are located on the circumference of a circle. The start point ST is located at one end of a straight line LN that passes through the center of the circle, and the end point ED is located at the other end of the straight line LN. The trajectory information T2 has a path T2a that arcs clockwise from the start point ST to the other end of the straight line LN. The trajectory information T2 also has a path T2b that passes along the straight line LN and moves from the other end of the straight line LN to one end of the straight line LN. The trajectory information T2 also has a path T2c that arcs counterclockwise from one end of the straight line LN to the end point ED. In the trajectory information T2, the electron beam is not irradiated when passing along the straight line LN. The trajectory information T2 may have a movement path formed by multiple beam sources 3c. The trajectory information T2 may include, for example, a first path that draws an arc clockwise from the start point ST to the end point ED, and a second irradiation point that draws an arc counterclockwise from the start point ST to the end point ED. Such trajectory information T2 does not satisfy the condition of being drawn in one stroke, and therefore does not need to be stored in the storage unit 41.

[0050] Trajectory information T3 shown in FIG. 4(c) is a reference example that does not satisfy the above-mentioned conditions. Trajectory information T3 has a single-stroke path that moves in a substantially rectangular shape. Trajectory information T3 has sides that are the first, second, third, and fourth sides in order of proximity to starting point ST, and each side is divided into two sections (first half section and second half section). Trajectory information T3 has a path 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 of the second side, and accelerates in the first half section A4 of the third side. Such trajectory information T3 does not need to be stored in memory unit 41 because the scanning speed fluctuates.

[0051] An example of processing by the counting unit 44 will be described with reference to the flowchart shown in FIG. 5. The counting unit 44 initializes the number of the frame to be processed (hereinafter referred to as "frame No.") and the number of frames F in which the electron beam is continuously projected (step S1). For example, the counting unit 44 sets the frame No. to 1 and the number of frames F to 0. Next, image analysis is performed on the frame to be processed (step S2). For example, the counting unit 44 analyzes the image of frame No. 1 to obtain the luminance of each pixel. The counting unit 44 counts the number of pixels whose luminance is equal to or greater than Lu, which is a luminance threshold.

[0052] The counting unit 44 determines whether the number of pixels with a brightness of Lu or more is equal to or greater than a threshold value E (step S3). If the number of pixels with a brightness of Lu or more is equal to or greater than the threshold value E, it indicates that the frame to be processed is an image taken during irradiation with the electron beam. On the other hand, if the number of pixels with a brightness of Lu or more is less than the threshold value E, it indicates that the frame to be processed is an image taken before or after irradiation with the electron beam.

[0053] If the number of pixels with a luminance equal to or greater than Lu is equal to or greater 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 increments the frame number (step S5). In other words, the counting unit 44 moves the frame to be processed to the next frame.

[0054] If the number of pixels with a brightness equal to or greater than Lu 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 the number of frames F is 0 (step S6). If the number of frames F is 0, this indicates that the frame being processed is before irradiation with the electron beam. In this case (Yes in step S6), the process proceeds to step S5. If the number of frames is not 0 (No in step S6), the process ends.

[0055] After step S5, the process returns to step S2. By returning to step S2, the frames to be processed are switched sequentially. When all processing is completed, the counting unit 44 outputs the frame number F. The frame number F indicates the number of images during irradiation with the electron beam.

[0056] Next, a three-dimensional printing method executed by the three-dimensional printing apparatus 1 will be described with reference to the flowchart shown in Fig. 6. It is assumed that heat input settings and beam irradiation settings are stored in advance in the storage unit 41. Hereinafter, it is assumed that the allowable ranges of parameters for heat input setting are scanning speed: 960 [mm / sec], and allowable error: ±20 [mm / sec].

[0057] As a first preparation step, the three-dimensional modeling apparatus 1 captures an image of the plate 51 (step S10). The three-dimensional modeling apparatus 1 captures an image of the plate 51 while irradiating the plate 51 with an electron beam according to the beam irradiation settings. The three-dimensional modeling apparatus 1 then acquires a video m including the irradiation point of the electron beam. More specifically, after the camera 7 starts capturing an image of the plate 51, the beam source 3c irradiates the plate 51 with the electron beam. The controller 4 controls the irradiation of the electron beam by the beam source 3c so that the trajectory of the electron beam is circular. The controller 4 also controls the irradiation of the electron beam by the beam source 3c so that the scanning speed is constant. If the scanning speed is not constant, the heat input may also vary depending on the scanning speed. In this disclosure, a scanning speed is considered to be "constant" if it is within a range in which unintended fluctuations in the scanning speed do not affect measurement accuracy. The term "constant" is defined as being within an allowable range for a parameter, which is the heat input setting. The controller 4 controls the irradiation of the electron beam so that the scanning speed is within the allowable range. When the irradiation of the electron beam stops, the camera 7 outputs the moving image m to the control unit 4.

[0058] The three-dimensional modeling apparatus 1 analyzes the moving image m for each frame (step S11). The three-dimensional modeling apparatus 1 acquires the number of frames F in which the electron beam is continuously captured based on the moving image m through the process shown in FIG.

[0059] The three-dimensional modeling apparatus 1 calculates the scanning length of the electron beam (step S12). The distance calculation unit 45 calculates the scanning length using the moving image m. The distance calculation unit 45 detects the trajectory of the electron beam by, for example, edge detection on the frame after irradiation with the electron beam, and calculates the length of the trajectory.

[0060] The three-dimensional modeling apparatus 1 calculates the scanning speed of the electron beam (step S13). If the frame rate of the video m is c [frame / sec], the shutter interval of the camera 7 is 1 / c [sec]. Assuming that the timing of the camera 7 to capture images is simultaneous with the start and end of the electron beam irradiation, the scanning time t can be expressed by the following equation (1) using the number of frames F [frame].

[0061]

number

[0062] However, the timing of the camera 7 to capture images is not necessarily synchronized with at least one of the start and stop of electron beam irradiation. Therefore, at least one of the start and stop of irradiation may miss up to 1 / c [sec] of an image. Therefore, the actual scanning time t [sec] satisfies the range of the following equation (2).

[0063]

number

[0064] Here, if 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 equations (1) and (2), the scanning speed v satisfies the range of the following equation (3).

[0065]

number

[0066] Therefore, the measured value of the velocity expressed by the following equation (4) is calculated by averaging the upper and lower limits that can be considered from the measurement results. m Defined as [mm / sec].

[0067]

number

[0068] The three-dimensional printing device 1 calculates the scanning speed v as the measurement result of the parameter using Equation (4). m The above-described steps S11 to S13 can be regarded as a second preparation step for acquiring measurement results of parameters that define the amount of heat input by analyzing the moving image m.

[0069] In the third preparation step, the three-dimensional modeling apparatus 1 performs scanning at a scanning speed vm (Step S14). The comparison unit 47 evaluates the measured scanning speed v m By determining whether or not the scanning speed v is within the allowable range of 940 to 980 mm / sec, m Evaluate.

[0070] Scanning speed v m is within the allowable range, it can be said that the amount of heat input actually given to the powder material P is appropriate. m It can be said that the heat input to the powder material P is appropriate in the molding operation performed immediately before or after measuring the amount of heat input. If the amount of heat input is appropriate, it can be said that the quality of the molded object evaluated based on the amount of heat input meets the standard.

[0071] In the modeling step, the three-dimensional modeling apparatus 1 spreads the powder material P evenly on the plate 51 and irradiates the spread powder material P with an electron beam, thereby forming a model PA (step S15).

[0072] The three-dimensional modeling method includes a first preparatory step of irradiating an electron beam onto a plate 51 in accordance with a heat input setting indicating the allowable range of a parameter that determines the heat input amount imparted to a powder material P by the electron beam and a beam irradiation setting including trajectory information that determines the irradiation position of the electron beam, and photographing the plate 51 to obtain a video m that includes the irradiation point of the electron beam; a second preparatory step of analyzing the video m to obtain measurement results of the parameter that determines the heat input amount; a third preparatory step of determining whether the measurement results are within the allowable range; and a modeling step of spreading the powder material P evenly on the plate 51 and irradiating the spread powder material P with the electron beam to form a model PA.

[0073] This three-dimensional printing method captures a video m of points irradiated with an electron beam according to beam irradiation settings, which include information specifying the allowable range of parameters that define the amount of heat input and the movement of the beam. The three-dimensional printing method analyzes the video m to obtain measurement results of the parameters. The three-dimensional printing method determines whether the measurement results are within the allowable range. In this case, it is determined whether the measurement results of the actual parameters are within the allowable range of the parameters. If the measurement results are within the allowable range, it is determined that the range of the amount of heat input to the object PA is within the allowable range. This makes it possible to ensure that the object PA has the desired printing quality.

[0074] The second preparation step counts the number of frames F in which the electron beam is continuously projected by determining whether each frame of the moving image m contains an irradiation point of the electron beam, and 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 in which the electron beam is projected, the length of the electron beam trajectory, and the frame rate of the moving image m. In this case, the actual speed at which the electron beam is projected is acquired as the measurement result. This makes it possible to more precisely ensure that the heat input, which is determined by the speed, is within an allowable range. Therefore, it becomes possible to ensure that the object PA has the desired printing quality.

[0075] In the first preparation step, the electron beam is irradiated so that the trajectory of the beam is circular. In this case, even in a narrow area on the plate 51, the distance irradiated with the electron beam becomes long, so it becomes possible to more accurately determine the irradiation trajectory. As a result, the measurement results can be more accurate.

[0076] In the first preparation step, the electron beam is irradiated so that the speed at which the electron beam moves along the trajectory is constant. In this case, the electron beam appears in the frame of the moving image m at a constant speed during irradiation of the electron beam. As a result, the measurement results can be obtained more accurately.

[0077] Additive manufacturing is a relatively new manufacturing technology. A molded object PA obtained by additive 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 a molded object PA manufactured by additive manufacturing has the desired quality has not yet been established. Heat input is one parameter that affects the quality of the molded object PA. If the heat input is too high or too low, defects will occur inside the molded object PA. Therefore, if it is possible to confirm that the heat input is properly managed, it is possible to at least prove that there are no defects caused by inadequate heat input. Therefore, the inventors have intensively studied a method capable of measuring the heat input of a molded object PA with sufficient accuracy to be applicable to quality control, and have come up with the three-dimensional printing method and three-dimensional printing apparatus 1 disclosed herein.

[0078] The three-dimensional printing apparatus 1 includes a beam source 3c that irradiates an electron beam onto a plate 51 in accordance with a heat input setting indicating an allowable range of a parameter that determines the amount of heat input imparted to a powder material P by the electron beam and a beam irradiation setting including trajectory information that determines the irradiation position of the electron beam; a camera 7 that captures an image of the plate 51 and outputs a video m that includes the electron beam irradiation point; and a control unit 4 that analyzes the video m to obtain measurement results of the parameter that determines the amount of heat input and determines whether the measurement results are within the allowable range. The beam source 3c spreads the powder material P evenly on the plate 51 and irradiates the spread powder material P with an electron beam to form a model PA. For the reasons described above, the three-dimensional printing apparatus 1 can ensure that the model PA has the desired printing quality.

[0079] The control unit 4 includes a counting unit 44 that counts the number of frames F in which the electron beam is continuously captured by determining whether or not an irradiation point of the electron beam is included in each frame of the moving image m, and a speed calculation unit 46 that acquires, as a measurement result, the speed at which the irradiation point of the electron beam moves along the trajectory, based on the number of frames F in which the electron beam is captured, the length of the trajectory of the electron beam, and the frame rate of the moving image m. Even in this case, for the reasons described above, it is possible to ensure that the modeled object PA has the desired modeling quality.

[0080] The control unit 4 controls the irradiation of the electron beam by 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.

[0081] The control unit 4 controls the irradiation of the electron beam by the beam source 3c so that the speed at which the electron beam moves along the trajectory is constant. Even in this case, the measurement results can be made more accurate for the reasons described above.

[0082] The three-dimensional printing method and three-dimensional printing 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.

[0083] In the embodiment, an example in which the scanning speed is acquired as the measurement result has been described, but the measurement result may also be the scanning length, the output of the electron beam, etc. In addition, in the three-dimensional printing method, the processing of step S15 may be performed before step S10. Even in these cases, if the measurement result is within the allowable range, it is clear that the range of the heat input amount to the molded object PA is within the allowable range. This makes it possible to ensure that the molded object PA has the desired printing quality.

[0084] The three-dimensional printing method may acquire a first measurement result by processing steps S10 to S14, and after processing step S15, further execute the processing steps S10 to S14 to acquire a second measurement result. In this case, if the first measurement result and the second measurement result are within a predetermined range, it can be evaluated that the measurement results of the parameters in the printing step (step S15) are stable.

[0085] The camera 7 may output an image of the plate 51 to the control unit 4 separately from the video m. For example, the camera 7 may output an image of the plate 51 after the irradiation of the electron beam has stopped to the control unit 4 in order to calculate the scanning length. The camera 7 may be provided inside the three-dimensional printing apparatus 1. The plate 51 may be rotating during parameter measurement, or powder material P may be placed on the plate 51. Even in these cases, it is possible to ensure that the model PA has the desired modeling quality for the reasons described above. [Explanation of symbols]

[0086] 1 3D printing equipment 2 Drive Unit 3 Processing Unit 3a Feeder 3b Heater 3c Beam source 4. Control Unit 5. Housing 6 Window section 7. Camera 21 Rotation drive mechanism 22 Lifting drive mechanism 41 Storage section 42 Beam control section 43 Acquisition Department 44 Counting Unit 45 Distance calculation unit 46 Speed ​​calculation section 47 Comparison Section 51 Plate 51a Plate main surface 52 Modeling Tank 101 processors 102 memory 103 Storage 104 Communication equipment 105 Input Device 106 Output Device 107 Bus φ control signal m video P powder material PA sculpture S Build space

Claims

1. a first preparation step of irradiating the energy beam onto a plate in accordance with a heat input setting indicating an allowable range of a parameter that defines the heat input amount imparted to the powder material by the energy beam and a beam irradiation setting including trajectory information that defines a trajectory where a start point and an end point of the irradiation position of the energy beam overlap, and capturing an image of the plate to obtain a video including the irradiation point of the energy beam; a second preparation step of acquiring measurement results of parameters that define the heat input amount by analyzing the video; a third preparation step of determining whether the measurement result is within the allowable range; a manufacturing process of manufacturing a three-dimensional object by irradiating the energy beam onto the powder material while spreading the powder material evenly on the plate; A three-dimensional modeling method comprising:

2. The second preparation step includes: Counting the number of frames in which the energy beam is continuously projected by determining whether or not the energy beam irradiation point is included in each frame of the video; The three-dimensional printing method according to claim 1, wherein the speed at which the irradiation point of the energy beam moves along the trajectory is obtained as the measurement result based on the number of frames over which the irradiation point of the energy beam moves, the length of the trajectory of the energy beam, and the frame rate of the video.

3. The three-dimensional modeling method according to claim 1 , wherein the first preparation step includes irradiating the energy beam so that the trajectory of the energy beam is circular.

4. 4. The three-dimensional modeling method according to claim 1, wherein the first preparation step irradiates the energy beam so that the speed at which the energy beam moves along the trajectory is constant.

5. an irradiation unit that irradiates the energy beam onto a plate in accordance with a beam irradiation setting including a heat input setting indicating an allowable range of a parameter that defines a heat input amount imparted to the powder material by the energy beam and trajectory information that defines a trajectory where a start point and an end point of the irradiation position of the energy beam overlap; an imaging unit that captures an image of the plate and outputs a video including the irradiation point of the energy beam; a control unit that analyzes the video to obtain a measurement result of a parameter that defines the heat input amount, and determines whether the measurement result is within the allowable range; The irradiation unit spreads a powder material evenly on the plate and irradiates the energy beam onto the powder material, thereby forming a three-dimensional object.

6. The control unit a counting unit that counts the number of frames in which the energy beam is continuously projected by determining whether or not the energy beam irradiation point is included in each frame of the moving image; a velocity calculation unit that acquires, as the measurement result, a velocity at which the irradiation point of the energy beam moves along the trajectory based on the number of frames in which the energy beam is captured, the length of the trajectory of the energy beam, and the frame rate of the video. The three-dimensional modeling apparatus according to claim 5 .

7. The three-dimensional modeling apparatus according to claim 5 , wherein the control unit controls the irradiation of the energy beam by the irradiation unit so that the trajectory of the energy beam becomes circular.

8. 8. The three-dimensional modeling apparatus according to claim 5, wherein the control unit controls the irradiation of the energy beam by the irradiation unit so that the speed at which the energy beam moves along the trajectory is constant.

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