Additive manufacturing method and additive manufacturing apparatus

Abstract

The temperature acquisition method according to this disclosure includes a temperature measurement step of measuring the temperature of a temperature measurement point on an object to be measured, whose temperature has been raised in advance, at multiple time series times using a thermometer, and a temperature estimation step of estimating the temperature of the temperature measurement point before the temperature was raised, based on the relationship between the multiple time series temperatures, which are the temperatures of the temperature measurement point measured at multiple time series times, and the multiple time series times, or based on the measured temperature measured in the temperature measurement step and the temperature increase value of the object to be measured when the temperature of the object to be measured is raised under predetermined conditions.

Description

[Technical Field]

[0001] This disclosure ,product Layered manufacturing method Law Regarding additive manufacturing equipment. [Background technology]

[0002] Additive manufacturing equipment that produces three-dimensional objects using the Direct Energy Deposition (DED) method is known. Some additive manufacturing equipment locally melts material with a beam emitted from a processing head and adds the molten material to the workpiece. Additive manufacturing equipment has the characteristic of enabling fabrication with a high degree of freedom. Additive manufacturing equipment can easily form shapes that are difficult to create by machining.

[0003] In additive manufacturing equipment, the object being manufactured is heated by the beam irradiation. When manufacturing objects using metal materials in additive manufacturing equipment, if additive manufacturing continues while the object is heated, the reaction between the heated object and oxygen in the atmosphere is accelerated, leading to increased oxidation of the object. Furthermore, as the object accumulates heat during manufacturing, the time required for the object to solidify increases. When the time required for the object to solidify increases, the stacked materials become more prone to collapsing due to the effects of gravity, causing the object to lose its shape. To suppress this deterioration in the quality of the object, interlayer waiting is sometimes performed, which involves providing a cooling time for the object between the manufacturing periods of each of the multiple layers of material stacked together to suppress oxidation.

[0004] Furthermore, the higher the temperature of the heat-accumulating molded object, the more the oxidation of the object is accelerated. Therefore, by allowing the molded object to wait between layers until its temperature drops to a level where oxidation is not actively promoted, oxidation of the molded object can be suppressed. For this reason, it is necessary to measure the temperature of the molded object during manufacturing in order to determine the interlayer waiting time, which is the time for interlayer waiting. Interlayer waiting is the waiting period between the manufacturing of each layer of a molded object.

[0005] Patent Document 1 discloses a 3D additive manufacturing apparatus that derives the temperature of a molten pool based on the brightness of an image of the molten pool.

[0006] Generally, in additive manufacturing systems, radiation thermometers are used to measure the temperature of the manufactured object. These radiation thermometers are sometimes mounted coaxially with the processing head. A beam is emitted from the processing head, which is fitted with quartz-derived components such as protective glass and collimating lenses. Quartz does not transmit light with wavelengths greater than 2.7 μm. Therefore, radiation thermometers cannot detect signals of light with wavelengths they do not transmit. For example, depending on the material of the sensor or optical components in the radiation thermometer, it may be difficult to measure temperatures below approximately 500°C in the manufactured object during interlayer waiting. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2017 / 163430 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The 3D additive manufacturing apparatus described in Patent Document 1 above uses a temperature measurement technique based on visible light, but it is limited to cases where metal materials are melting. It was sometimes difficult to measure the temperature of a manufactured object where the molten pool cannot be observed, such as during interlayer waiting, for example, temperatures below 500°C. In other words, with the 3D additive manufacturing apparatus described in Patent Document 1 above, it was sometimes impossible to obtain the temperature of the workpiece, and thus the accuracy of additive manufacturing could not be improved.

[0009] This disclosure has been made in view of the above, and aims to provide a temperature acquisition method that can appropriately acquire the temperature of an object to be measured. [Means for solving the problem]

[0010] To solve the above-mentioned problems and achieve the objective, the temperature acquisition method according to this disclosure includes a temperature measurement step of measuring the temperature of a temperature measurement point on an object to be measured, which has been pre-heated, at multiple time series points using a thermometer, and a temperature estimation step of estimating the temperature of the temperature measurement point before the temperature was raised, based on the relationship between the multiple time series temperatures, which are the temperatures of the temperature measurement point measured at multiple time series points, and the multiple time series points, or based on the measured temperature measured in the temperature measurement step and the temperature increase value of the object to be measured when the temperature of the object to be measured is raised under predetermined conditions. [Effects of the Invention]

[0011] According to this disclosure, the temperature of the object being measured can be appropriately obtained. [Brief explanation of the drawing]

[0012] [Figure 1] This figure schematically shows an example of the configuration of an additive manufacturing apparatus according to Embodiment 1. [Figure 2] This figure shows an example of an NC (Numerical Control) device included in the additive manufacturing apparatus according to Embodiment 1. [Figure 3] Figure 1 schematically shows how laser marks are formed on the surface of a fabricated object in the additive manufacturing apparatus according to Embodiment 1. [Figure 4] Figure 2 schematically shows how laser marks are formed on the surface of a fabricated object in the additive manufacturing apparatus according to Embodiment 1. [Figure 5] This figure shows an example of the temporal change between the laser beam output and the temperature at the laser mark formation site when forming a laser mark on the surface of an object using the additive manufacturing apparatus according to Embodiment 1. [Figure 6] This figure shows an example of temperature change at the laser mark formation site when a laser mark is formed on an object using the additive manufacturing apparatus according to Embodiment 1. [Figure 7]This figure shows an example of temperature change at the laser mark formation site in an object fabricated by the additive manufacturing apparatus according to Embodiment 1. [Figure 8] A flowchart showing an example of the additive manufacturing process using the additive manufacturing apparatus in Embodiment 2. [Figure 9] A flowchart showing an example of the interlayer waiting process procedure by the additive manufacturing apparatus in Embodiment 2. [Figure 10] A flowchart showing an example of the procedure for other additive manufacturing processes using the additive manufacturing apparatus in Embodiment 2. [Figure 11] This figure shows an example of the temporal changes in the laser beam output and the temperature of the laser trace formation site during the additive manufacturing period of each layer in other additive manufacturing processes using the additive manufacturing apparatus in Embodiment 2. [Figure 12] This figure shows an example of the temperature immediately before irradiation and the temperature immediately after irradiation, obtained by the additive manufacturing apparatus in Embodiment 3, which are obtained just before the formation of the laser trace. [Figure 13] Figure 1 schematically shows how a laser mark is formed on the surface temperature measurement location of an object by an additive manufacturing apparatus in Embodiment 3. [Figure 14] Figure 2 schematically shows how a laser mark is formed on the surface temperature measurement location of an object by an additive manufacturing apparatus in Embodiment 3. [Figure 15] Block diagram showing an example of the hardware configuration of the NC device in the additive manufacturing apparatus according to Embodiment 1. [Modes for carrying out the invention]

[0013] The following describes the embodiments. The product Layered manufacturing method Law The additive manufacturing apparatus will be described in detail based on the drawings.

[0014] Embodiment 1. Figure 1 is a schematic diagram showing an example of the configuration of an additive manufacturing apparatus 100 according to Embodiment 1. The additive manufacturing apparatus 100 according to Embodiment 1 is an apparatus having DED-type additive manufacturing technology. The additive manufacturing apparatus 100 melts the material 5, which is the manufacturing material, with a laser beam 9 and performs additive manufacturing by adding the molten material 5 to the manufactured object 15, which is a base material 14 or a base material 14 to which the molten material 5 has been added. The additive manufacturing apparatus 100 is controlled by an NC device 1. The manufactured object 15, which is a base material 14 or a base material 14 to which the molten material 5 has been added, can be said to be the workpiece in the additive manufacturing apparatus 100.

[0015] In Figure 1, the X, Y, and Z axes are perpendicular to each other. The X and Y axes are two mutually orthogonal axes in the horizontal direction. The Z axis is a vertical axis. For each of the X, Y, and Z axes, the direction indicated by the arrow in Figure 1 is the + direction, and the direction opposite to the direction indicated by the arrow is the - direction. The Z axis direction is the stacking direction, which is the direction in which the printed objects 15 are stacked.

[0016] The additive manufacturing apparatus 100 comprises an NC device 1, a laser oscillator 2, a fiber optic cable 3, a material supply device 4, a gas supply device 6, piping 7, a processing head 8, a material nozzle 11, a head drive device 12, a stage 13, protective glass 16, and a radiation thermometer 17.

[0017] The laser oscillator 2 outputs a laser beam 9, which is a heat source that melts the material 5. The laser oscillator 2 corresponds to the beam heat source supply unit. Note that the beam is not limited to a laser beam 9, but may also be an arc or an electron beam. In the following description, the beam output of the laser beam 9 is also referred to as the laser output. The fiber cable 3 propagates the laser beam 9 output by the laser oscillator 2 to the processing head 8.

[0018] The processing head 8 emits a laser beam 9 toward the object 15. The processing head 8 has a collimating lens 24 inside that parallelizes the laser beam 9, a focusing lens 25 that focuses the laser beam 9, and protective glass 16 that prevents powdered material from entering the inside of the processing head 8.

[0019] The processing head 8 can be moved in the X-axis, Y-axis, and Z-axis directions by driving the head drive device 12. The direction of the center line of the laser beam 9 that is irradiated onto the workpiece from the processing head 8 is in the Z-axis direction. If the beam is a laser beam 9, the center line is preferably the optical axis, for example. If the beam is something other than a laser beam 9, the center line is preferably the point in the beam's irradiance distribution where the irradiance is strongest. The position of the center line may deviate from the optical axis, the point of strongest irradiance, etc., as exemplified above, to the extent that it does not cause problems in controlling the parameters of additive manufacturing performed based on the position through which the center line passes. For example, the center line of the beam can be an axis that passes through the inside of the beam or near the outer edge of the beam, within a range determined from the outer edge of the beam, and is substantially parallel to the direction of beam propagation.

[0020] The processing head 8 is equipped with a gas nozzle that supplies shielding gas 10. The additive manufacturing apparatus 100 sprays the shielding gas 10, which has been sent from the gas supply device 6 through the piping 7 to the processing head 8, toward the manufactured object 15, thereby suppressing oxidation of the manufactured object 15 and cooling the manufactured object 15. Examples of shielding gas 10 include inert gases such as argon, nitrogen, and carbon dioxide.

[0021] The molding material supply unit supplies a metal wire material 5, which is the molding material, to a molded object 15 that is a base material 14 supported on a stage 13 or a base material 14 to which molten material 5 has been added. The molding material supply unit has a material supply device 4 which is the source of the material 5.

[0022] The material supply device 4 supplies material 5 via the material nozzle 11 towards the area on the base material 14 or the object 15 that is irradiated by the laser beam 9. The material nozzle 11 guides the material 5 supplied from the material supply device 4 so that it is supplied towards the area on the base material 14 or the object 15 that is irradiated by the laser beam 9. The direction in which the material 5 is supplied is oblique to the direction in which the laser beam 9 is emitted from the processing head 8.

[0023] The radiation thermometer 17 is attached to the processing head 8. The light-receiving part of the radiation thermometer 17 (not shown) is located inside the processing head 8. The radiation light emitted from the base material 14 or the object 15 passes inside the processing head 8 and is received by the light-receiving part of the radiation thermometer 17. This allows the radiation thermometer 17 to measure the temperature of the base material 14 or the object 15. Before the radiation light emitted from the base material 14 or the object 15 is received by the light-receiving part of the radiation thermometer 17, it passes through the protective glass 16, the collimating lens 24, and the focusing lens 25. The radiation thermometer 17 is called a coaxial radiation thermometer because the path through which the radiation light is received by the radiation thermometer 17 is approximately coaxial with the laser beam 9 irradiated from the processing head 8.

[0024] In Figure 1, the radiation thermometer 17 is shown directly above the machining head 8, but it does not have to be mounted directly above the machining head 8. The radiation thermometer 17 may be mounted, for example, on the side of the machining head 8. When the radiation thermometer 17 is mounted on the side of the machining head 8, it is configured so that the radiation thermometer 17 can receive the radiation light emitted from the base material 14 or the molded object 15 by reflecting it with a mirror or beam splitter. Alternatively, instead of the radiation thermometer 17, an infrared thermograph may be used to measure the temperature of the base material 14 or the molded object 15.

[0025] The NC device 1 controls the entire additive manufacturing apparatus 100 according to the processing program 18. The NC device 1 controls the laser oscillator 2 by commanding the laser output. The NC device 1 controls the coordinates of the processing head 8 by outputting axis commands to the head drive device 12. The NC device 1 controls the amount of material supplied by commanding the material supply amount to the material supply device 4. The NC device 1 controls the flow rate of the shielding gas 10 by outputting a gas supply command to the gas supply device 6.

[0026] Figure 2 shows an example of an NC device 1 included in the additive manufacturing apparatus 100 according to Embodiment 1. The NC device 1 receives a machining program 18, which is an NC program. The machining program 18 is created by a CAM (Computer Aided Manufacturing) device.

[0027] The NC device 1 controls the entire additive manufacturing apparatus 100 by outputting various commands. The NC device 1 includes a condition data table 20a that stores layering condition data indicating the layering conditions of the manufactured object 15, a storage unit 20 that stores information used to control the additive manufacturing apparatus 100, a program analysis unit 21 that analyzes the processing program 18, an inter-layer waiting time calculation unit 22 that calculates the inter-layer waiting time, and a command value generation unit 23 that generates various command values.

[0028] The program analysis unit 21 analyzes the processing in the processing program 18 that will be performed after the currently running processing, based on the description of the processing program 18. By analyzing the content of the processing described in the processing program 18, the program analysis unit 21 determines the movement path that moves the supply position of the material 5 in the molded object 15. The program analysis unit 21 outputs data indicating the movement path to the command value generation unit 23.

[0029] The interlayer waiting time calculation unit 22 performs an interlayer waiting time determination process to calculate the interlayer waiting time, which is the time spent waiting between the manufacturing of each layer of the molded object 15. The interlayer waiting time calculation unit 22 can perform a temperature prediction process and a temperature estimation process in order to calculate the interlayer waiting time. Details of the interlayer waiting time determination process, temperature prediction process, and temperature estimation process will be described later.

[0030] The temperature acquisition device 120 is comprised of an interlayer waiting time calculation unit 22 and a radiation thermometer 17. In the manufacturing of the molded object 15, the temperature acquisition device 120 can raise the temperature of the molded object 15 by forming a laser mark 26 on the surface of the molded object 15 and measure the temperature at the location where the laser mark 26 is formed. The temperature acquisition device 120 estimates the interlayer temperature before the formation of the laser mark 26 from the temperature transition of the molded object 15 after the formation of the laser mark 26.

[0031] The command value generation unit 23 generates position commands, which are interpolated point groups for each unit time along the movement path, based on data indicating the movement path. Interpolated points are also called command points. The command value generation unit 23 outputs the position commands to the head drive device 12. The head drive device 12 drives the machining head 8 according to the position commands input from the command value generation unit 23.

[0032] The program analysis unit 21 determines the amount of material 5 supplied to the irradiation position of the laser beam 9 and the output of the laser beam 9 based on the description of the processing program 18. The program analysis unit 21 outputs a supply amount command value specifying the amount of material 5 supplied to the irradiation position of the laser beam 9 and an output command value specifying the output of the laser beam 9 to the command value generation unit 23.

[0033] The command value generation unit 23 generates a supply command instructing the supply of material 5 to the irradiation position of the laser beam 9, based on the supply quantity command value input from the program analysis unit 21. The command value generation unit 23 outputs the generated supply command to the material supply device 4. The material supply device 4 supplies material 5 to the irradiation position of the laser beam 9 according to the supply command input from the command value generation unit 23.

[0034] The command value generation unit 23 generates an output command that instructs the output of the laser beam 9 based on the output command value input from the program analysis unit 21. The command value generation unit 23 outputs the generated output command to the laser oscillator 2. The laser oscillator 2 oscillates the laser beam 9 according to the output command input from the command value generation unit 23.

[0035] Interlayer temperature data 19 is input to the NC device 1. Interlayer temperature is the temperature of the object 15 during the manufacturing period of each layer formed when the object 15 is fabricated. Interlayer temperature data 19 is data on the interlayer temperature. Interlayer temperature data 19 is acquired by a radiation thermometer 17 attached to the additive manufacturing device 100 and input to the NC device 1.

[0036] Figure 3 is a first diagram schematically showing how laser marks 26 are formed on the surface of a fabricated object 15 in the additive manufacturing apparatus 100 according to Embodiment 1. Figure 4 is a second diagram schematically showing how laser marks 26 are formed on the surface of a fabricated object 15 in the additive manufacturing apparatus 100 according to Embodiment 1. Figure 3 shows the laser beam 9 being irradiated onto the surface of the fabricated object 15. Figure 4 shows the laser marks 26 formed on the surface of the fabricated object 15 after the laser beam 9 has been irradiated onto the fabricated object 15.

[0037] In Figure 3, when forming laser marks 26 on the surface of the fabricated object 15, the processing head 8 irradiates the surface of the fabricated object 15 with a laser beam 9 for an irradiation time of 0.1 seconds or more and not exceeding 10 seconds. When forming laser marks 26 on the surface of the fabricated object 15, the material supply device 4 does not supply material 5 to the fabricated object 15. Also, when forming laser marks 26 on the surface of the fabricated object 15, the head drive device 12 does not drive the processing head 8.

[0038] In Figure 4, the laser marks 26 formed on the fabricated object 15 by irradiation with the laser beam 9 are heated by the heat input of the laser beam 9, and therefore immediately after irradiation with the laser beam 9, the temperature of the areas of the fabricated object 15 other than the laser marks 26 is higher. The process of forming the laser marks 26 corresponds to the temperature rise process. The temperature rise process is performed between the fabrication periods of each layer of the fabricated object 15. Note that the areas on the surface of the fabricated object 15 where the laser marks 26 are formed may be referred to as "laser mark formation areas".

[0039] The location where the laser marks 26 are formed on the surface of the fabricated object 15 does not have to be one. For example, the laser marks 26 may be formed at two or more locations on the surface of the fabricated object 15 where the temperature is measured. Furthermore, when forming two or more laser marks 26 on the surface of the fabricated object 15, the output of the laser beam 9 and the irradiation time of the laser beam 9 may differ depending on the location where the laser marks 26 are formed.

[0040] Figure 5 shows an example of the temporal change between the output of the laser beam 9 and the temperature T at the laser mark formation site when forming a laser mark 26 on the surface of an object 15 using the additive manufacturing apparatus 100 according to Embodiment 1. In Figure 5, the upper characteristic diagram shows the time transition of the laser output, which is the output of the laser beam 9, from before the formation of the laser mark 26 to after the formation of the laser mark 26. In the upper characteristic diagram of Figure 5, time t is shown on the horizontal axis and the laser output is shown on the vertical axis. Also in Figure 5, the lower characteristic diagram shows the time transition of the temperature T at the laser mark formation site on the object 15 from before the formation of the laser mark 26 to after the formation of the laser mark 26. In the lower characteristic diagram of Figure 5, time t is shown on the horizontal axis and the temperature T is shown on the vertical axis.

[0041] The time immediately after irradiation of the surface of the fabricated object 15 with the laser beam 9 and the temperature of the laser mark formation area on the fabricated object 15 immediately after irradiation with the laser beam 9 are defined as follows: a , temperature T immediately after irradiation aThis is referred to as [the term]. Furthermore, the time immediately before the laser beam 9 is irradiated onto the surface of the fabricated object 15 and the temperature of the laser mark 26 formation site on the fabricated object 15 immediately before the laser beam 9 is irradiated onto the surface of the fabricated object 15 are defined as [the term]. b , temperature T just before irradiation b This is referred to as [the period immediately before irradiation by laser beam 9]. Furthermore, "immediately before irradiation by laser beam 9" includes the period from the instantaneous moment immediately before irradiation by laser beam 9 to several tens of minutes before irradiation by laser beam 9, and is not limited to the instantaneous moment immediately before irradiation by laser beam 9.

[0042] Time t immediately before irradiation b From the time t immediately after irradiation a As the laser beam 9 heats up the object 15, the temperature T of the laser-marked area rises. As the temperature T of the laser-marked area rises, the temperature difference between the temperature T of the laser-marked area and the surrounding temperature of the object 15 increases. This increases the heat dissipation from the laser-marked area, and the rate at which the temperature T of the laser-marked area rises per unit time decreases.

[0043] The temperature T of the laser mark formation site is determined by the temperature rise caused by irradiation with the laser beam 9, immediately after irradiation at time t a It reaches its maximum at time t immediately after irradiation. a From this point onward, there is no heat input from the laser beam 9 to the laser mark formation area, and the temperature T of the laser mark formation area gradually decreases. The location where the temperature of the fabricated object 15 is measured does not have to be the laser mark formation area. The location where the temperature of the fabricated object 15 is measured may be any location on the surface of the fabricated object 15 where the temperature has risen due to the formation of the laser mark 26. The location where the temperature of the fabricated object 15 is measured does not have to be just one location. For example, the temperature of the fabricated object 15 may be measured at two or more locations on the surface of the fabricated object 15 where the temperature has risen due to the formation of the laser mark 26.

[0044] Next, the effects obtained by the additive manufacturing apparatus 100 according to Embodiment 1 forming the laser marks 26 on the surface of the formed object 15 will be described. FIG. 6 is a diagram showing an example of the change in the temperature T at the location where the laser marks 26 are formed on the formed object 15 by the additive manufacturing apparatus 100 according to Embodiment 1. In FIG. 6, the temperature T immediately before irradiation at the time t b immediately before irradiation in the additive manufacturing apparatus 100 b and the temperature T immediately after irradiation at the time t a immediately after irradiation are shown. In FIG. 6, the horizontal axis represents the time t, and the vertical axis represents the temperature T at the location where the laser marks are formed. The measurable minimum temperature T a in FIG. 6 indicates the lowest temperature measurable by the radiation thermometer 17. The temperature rise value ΔT in FIG. 6 is the temperature rise value at the location where the laser marks are formed due to the irradiation of the laser beam 9. measure_min is the lowest temperature measurable by the radiation thermometer 17. The temperature rise value ΔT in FIG. 6 is the temperature rise value at the location where the laser marks are formed due to the irradiation of the laser beam 9.

[0045] The radiation thermometer 17 is attached coaxially with the central axis of the processing head 8. The radiation light emitted from the base material 14 or the formed object 15 passes through the inside of the processing head 8, passes through the protective glass 16, the collimating lens 24, and the condenser lens 25, and is received by the light receiving portion of the radiation thermometer 17. Thereby, the radiation thermometer 17 measures the temperature at the location where the radiation light is emitted.

[0046] The protective glass 16, the collimating lens 24, and the condenser lens 25 are derived from quartz glass and do not transmit light with a wavelength of 2.7 μm or more. Therefore, the light received by the radiation thermometer 17 is light with a wavelength of less than 2.7 μm, and the radiation thermometer 17 cannot obtain a temperature of 400° C. or more and less than 800° C. For this reason, the radiation thermometer 17 of the additive manufacturing apparatus 100 has the measurable minimum temperature T measure_min which is the lowest measurable temperature.

[0047] In FIG. 6, the temperature T immediately before irradiation, which is the temperature at the planned location of formation of the laser marks 26 at the time t b immediately before irradiation, b is lower than the measurable minimum temperature T measure_min On the other hand, at the time t immediately after irradiationa The temperature immediately after irradiation is the temperature at the laser mark formation site. a is the lowest measurable temperature T measure_min It is higher. Therefore, immediately after irradiation time t a In this case, the temperature immediately after irradiation T is measured by a radiation thermometer 17 mounted coaxially with the processing head 8. a This makes it possible to measure the temperature of the laser mark formation site. The process of measuring the temperature of the laser mark formation site corresponds to the temperature measurement process performed by the radiation thermometer 17.

[0048] Note that in Figure 6, the temperature T immediately before irradiation is b is the lowest measurable temperature T measure_min Although a lower example is shown, the temperature T immediately before irradiation is shown. b is the lowest measurable temperature T measure_min It can be even more expensive.

[0049] Figure 7 shows an example of the change in temperature T at the laser trace formation site in a fabricated object 15 on which a laser trace 26 has been formed by the additive manufacturing apparatus 100 according to Embodiment 1. In Figure 7, the time t immediately after irradiation in the fabricated object 15. a This shows the time transition of the temperature T at the laser mark formation site. In Figure 7, the horizontal axis shows time t, and the vertical axis shows the temperature T at the laser mark formation site measured by the radiation thermometer 17.

[0050] The radiation thermometer 17 measured time t immediately after irradiation. a From t1, t2, t3, t4, ... n The time-series temperatures T1, T2, T3, T4, ... are obtained at a later time. n Each of these is measured and obtained. Immediately after irradiation temperature T a The number of samples is n, where n is any integer greater than or equal to 3. The acquired time-series temperature data is temperature T1, T2, T3, T4, ... n The data is a time series of t1, t2, t3, t4, ... t n The data is associated with and stored in the memory unit 20 of the NC device 1. The temperature immediately after irradiation is T. a The number of samples is n, where n is any integer greater than or equal to 3.

[0051] The temperature T at the laser mark formation site is expressed by the following equation (1).

[0052]

number

[0053] In equation (1), "t" represents the time t immediately after irradiation. a This shows the elapsed time from [the point]. In equation (1), "f" represents a function for determining the temperature T of the laser mark 26 formed on the fabricated object 15, and the contents of the parentheses () indicate that they are variables of the function f. The function f has the property that as t becomes large, T becomes small. For example, the function f can be simplified and expressed by equation (2) below.

[0054]

number

[0055] The constant K used in equation (2) i (i=1,2,3) is a constant that changes depending on processing parameters such as the laser output of the laser beam 9 and the irradiation time of the laser beam 9 onto the fabricated object 15 when forming the laser trace 26, the surrounding environment of the additive manufacturing apparatus 100, the shape of the fabricated object 15, the position of the laser trace 26 formation on the fabricated object 15, and the physical properties of the fabricated object 15, such as the temperature of the fabricated object 15 before the formation of the laser trace 26. The surrounding environment of the additive manufacturing apparatus 100 includes the atmosphere around the additive manufacturing apparatus 100 and the temperature around the additive manufacturing apparatus 100. Constant K i (i=1,2,3) are time-series temperature data stored in the memory unit 20 of the NC device 1, namely temperatures T1, T2, T3, T4, ...T n The data and time-series data t1, t2, t3, t4, ... n Based on the data and its relationship to equation (2), the constant K can be calculated using the least squares method. i The calculation of (i=1,2,3) is performed when each build layer is created.

[0056] The first term of equation (2) shows the effect of temperature due to heat input during the formation of the laser marks 26. As time passes from immediately after the formation of the laser marks 26, the effect of heat input due to the formation of the laser marks 26 decreases exponentially. From this, as time t increases, equation (2) approaches the temperature of the fabricated object 15 when there is no heat input from the laser beam 9. For this reason, the second term of equation (2) can be considered as the temperature of the fabricated object 15 when there is no heat input from the laser beam 9, that is, before heat input from the laser beam 9 is performed.

[0057] Therefore, by using equation (2), the fabricated object 15 reaches the target temperature T immediately after the formation of the laser trace 26. target The cooling time t is the time it takes for the material to cool down to a certain point. wait It is possible to estimate and calculate the cooling time t. wait This can be called interlayer waiting time. The time-series temperature data is temperature T1, T2, T3, T4, ...T n The data and time-series data t1, t2, t3, t4, ... n Based on the data, the fabricated object 15 reaches the target temperature T immediately after the formation of the laser trace 26. target The cooling time t is the time it takes for the material to cool down to a certain point. wait The process of estimating and determining corresponds to the interlayer waiting time determination process. In other words, in the interlayer waiting time determination process, it is possible to estimate the interlayer temperature by monitoring the temperature T of the measured laser trace 26 and determine the time required for interlayer waiting.

[0058] In the interlayer waiting time determination process, the time from the completion of the lower layer of the fabricated object 15 to the start of the additive manufacturing of the upper layer on top of the lower layer is determined. Target temperature T target This is determined by the target accuracy of the material 5 or the fabricated object 15. Target temperature T target The closer the temperature is to the ambient temperature of the additive manufacturing device 100, the less the deformation of the shape of the manufactured object 15 due to heat accumulation will be. For example, if the material 5 is an aluminum alloy, the target temperature T targetThe temperature is set to a range between 50°C and 400°C.

[0059] By using equation (2), the temperature of the fabricated object 15 after any time has elapsed since the laser mark 26 was formed, i.e., the temperature immediately after irradiation time t, can be calculated. a This makes it possible to predict the temperature of the fabricated object 15 after any given time has elapsed. The step of predicting the temperature of the fabricated object 15 after any given time has elapsed since the formation of the laser trace 26 using equation (2) corresponds to the temperature prediction step. In the temperature prediction step, multiple time-series temperatures at multiple time points are obtained, and based on the relationship between the multiple time points and the multiple time-series temperatures, the temperature T of the laser trace formation site, which is a temperature measurement site at a non-measurement time point when the temperature of the temperature measurement site is not measured, is estimated. In other words, in the temperature prediction step, it is possible to predict the temperature of the fabricated object 15 after any given time has elapsed since the laser beam 9 was irradiated and the laser trace 26 was formed, based on the relationship between the elapsed time and the measured temperature of the laser trace 26.

[0060] The function f in equation (1) does not have to be expressed in equation (2), as long as it is a function that has the property that T becomes small when t becomes large. The function f in equation (1) may also be expressed as, for example, in equation (3) below.

[0061]

number

[0062] The constant K2 is the temperature of the fabricated object 15 before the formation of the laser trace 26, which is the temperature immediately before irradiation T. b There is a positive correlation between this and the temperature T immediately before irradiation, which is the temperature of the fabricated object 15 before the formation of the laser trace 26. b This can be expressed by the following equation (4).

[0063]

number

[0064] In equation (4), "g" is the temperature T immediately before irradiation. bThis indicates that it is a function that calculates the temperature T immediately before irradiation when K2 is large. b Any function that has the property of taking a large value is acceptable. The function g can be simplified and expressed by, for example, equation (5) below.

[0065]

number

[0066] The constant l used in equation (5) i (i=1,2) is a constant that changes depending on the laser output of the laser beam 9 when forming the laser trace 26, the irradiation time of the laser beam 9 onto the fabricated object 15, the surrounding environment of the additive manufacturing device 100, the shape of the fabricated object 15, and the position where the laser trace 26 is formed on the fabricated object 15.

[0067] constant l i The method for calculating K2 is explained below. First, under the same conditions as the laser output of the laser beam 9 when forming the laser trace 26, the irradiation time of the laser beam 9 onto the fabricated object 15, the surrounding environment of the additive manufacturing device 100, the shape of the fabricated object 15, and the formation position of the laser trace 26 on the fabricated object 15, K2 is calculated based on the relationship between the time-series temperature data and time-series time data after the formation of the laser trace 26 and equation (2), and the temperature of the fabricated object 15 before the formation of the laser trace 26, which is the temperature immediately before irradiation T. b And, the group (T bm ,K 2m Find multiple values ​​of ). Here, m is a constant l i This represents the number of sampling steps required to form the laser trace 26 in order to obtain the result, and is any integer greater than or equal to 2. Next, the multiple sets obtained (T bm ,K 2m Based on the relationship between () and equation (5), the constant l can be calculated using the least squares method. i Calculate the temperature T immediately before irradiation from K2. bThe process of calculating corresponds to a temperature estimation process that estimates the temperature of the temperature measurement point before the temperature is increased, based on the relationship between multiple time-series temperatures, which are the temperatures of the laser marks 26, which are temperature measurement points measured at multiple time series, and the multiple time series times. Furthermore, the fabricated object 15 can be said to be the object of measurement, which is the object of measurement for the temperature of the temperature measurement point before the temperature is increased.

[0068] According to the additive manufacturing apparatus 100 of the above-described embodiment 1, when performing additive manufacturing with the additive manufacturing apparatus 100, a temperature acquisition method can be implemented that includes: a temperature measurement step of measuring the temperature of a temperature measurement point on the object to be measured, whose temperature has been raised in advance, at multiple time series points using a thermometer; and a temperature estimation step of estimating the temperature of the temperature measurement point before the temperature was raised, based on the relationship between the multiple time series temperatures, which are the temperatures of the temperature measurement point measured at multiple time series points, and the multiple time series points, or based on the measured temperature measured in the temperature measurement step and the temperature rise value of the object to be measured when the temperature of the object to be measured is raised under predetermined conditions.

[0069] As described above, the additive manufacturing apparatus 100 according to Embodiment 1 irradiates the manufactured object 15 with a laser beam 9 to form a laser mark 26. Immediately after the formation of the laser mark 26, the temperature of the laser mark 26 rises due to the heat input of the laser beam 9. The radiation thermometer 17, which is mounted coaxially with the processing head 8, receives the radiation from the manufactured object 15 through quartz glass such as protective glass 16, collimating lens 24, and focusing lens 25, and therefore cannot obtain a temperature of 400°C or higher and less than 800°C. For this reason, the additive manufacturing apparatus 100 cannot directly measure the temperature of the manufactured object 15 during the additive manufacturing period of each layer while the manufactured object 15 is cooling after the additive manufacturing process of the layers made of material 5.

[0070] However, the additive manufacturing apparatus 100 forms a laser trace 26 on the manufactured object 15 after the additive manufacturing process of each layer, thereby reducing the temperature to the lowest measurable temperature T that can be measured by the radiation thermometer 17. measure_minSince the temperature of the fabricated object 15 can be raised to the above temperature, the radiation thermometer 17 can measure the temperature of the fabricated object 15 during the additive manufacturing period of each layer. The interlayer waiting time calculation unit 22 uses the information on the time transition of the temperature T of the fabricated object 15 at the laser trace formation site immediately after the formation of the laser trace 26, so that the temperature of the fabricated object 15 at the laser trace formation site reaches the target temperature T. target The time required to cool down to that point can be estimated. Furthermore, the temperature T in equation (2) above can be considered as the temperature of the fabricated object 15 when no heat is being input by the laser beam 9.

[0071] In other words, the interlayer waiting time calculation unit 22 calculates the constant K in equation (2) above, which is a sum of the following for the additive manufacturing apparatus 100 and the manufactured object 15: processing parameters such as the laser output and irradiation time of the laser beam 9 when forming the laser trace 26, the surrounding environment of the additive manufacturing apparatus 100, the shape of the manufactured object 15, the formation position of the laser trace 26 on the manufactured object 15, and physical properties of the manufactured object 15 such as the temperature of the manufactured object 15 before the formation of the laser trace 26. i It is possible to calculate this.

[0072] This allows the interlayer waiting time calculation unit 22 to estimate the temperature of the fabricated object 15 during the additive manufacturing period of each layer using the measurement results of the radiation thermometer 17 located coaxially with the processing head 8. Furthermore, the interlayer waiting time calculation unit 22 uses the calculated constant K i From this value, it becomes possible to estimate the interlayer temperature at the laser trace formation site immediately before the formation of the laser trace 26.

[0073] Furthermore, the interlayer waiting time calculation unit 22 calculates the constant l of the above formula (5), which summarizes the processing parameters when forming the laser trace 26 for the additive manufacturing apparatus 100 and the manufactured object 15, the surrounding environment of the additive manufacturing apparatus 100, the shape of the manufactured object 15, the formation position of the laser trace 26 on the manufactured object 15, and the physical properties of the manufactured object 15. i It is possible to calculate this.

[0074] This allows the interlayer waiting time calculation unit 22 to estimate the temperature of the fabricated object 15 at the laser trace formation location before the formation of the laser trace 26 during the additive manufacturing period of each fabrication layer.

[0075] In other words, with the additive manufacturing apparatus 100, by forming a laser trace 26, it is possible to raise the temperature of the fabricated object 15 at the temperature measurement point and measure the temperature, and the interlayer temperature before the formation of the laser trace 26 can be estimated from the temperature transition of the fabricated object 15 after the formation of the laser trace 26. As a result, the additive manufacturing apparatus 100 can estimate the lowest measurable temperature T of the radiation thermometer 17 in the fabricated material or workpiece. measure_min It is possible to obtain temperatures in a lower temperature range than before, and since additive manufacturing can be performed based on the obtained temperature, the accuracy of additive manufacturing can be improved.

[0076] Therefore, according to the additive manufacturing apparatus 100, the minimum measurable temperature T of the radiation thermometer 17 is measure_min This has the effect of enabling the proper acquisition of the workpiece temperature in a lower temperature range than that of other methods.

[0077] Embodiment 2. Embodiment 2 describes the additive manufacturing process using the additive manufacturing apparatus 100. Figure 8 is a flowchart showing an example of the procedure for additive manufacturing using the additive manufacturing apparatus 100 in Embodiment 2.

[0078] In step S1, the processing head 8 irradiates a laser beam 9 onto the build area of ​​the workpiece where the build layers are to be constructed. Step S1 corresponds to a beam heat source supply process in which the laser beam 9 that melts the workpiece is irradiated onto the build area of ​​the workpiece.

[0079] In step S2, the material supply device 4 supplies the material 5, which is the molding material, to the molding area on the workpiece that is irradiated by the laser beam 9, via the material nozzle 11. Step S2 corresponds to the molding material supply process, in which the molding material is supplied to the workpiece.

[0080] Steps S1 and S2 perform a first additive manufacturing process, which includes a beam heat source supply process and a molding material supply process, to build up layers of material 5 on a workpiece. After the first additive manufacturing process is completed, the irradiation of the laser beam 9 and the supply of material 5 are stopped.

[0081] In step S3, the NC device 1 controls the interlayer waiting period to cool the fabricated object 15 after the fabricated layers have been created. Then, the process returns to step S1, and the second additive manufacturing process is carried out by performing steps S1 and S2. The additive manufacturing device 100 repeats the above operations to repeatedly build up layers and construct the fabricated object 15. Step S3 corresponds to the interlayer waiting period, which is the waiting period from the end of the first additive manufacturing process until the start of the second additive manufacturing process.

[0082] Next, we will describe the details of the interlayer waiting process in step S3 described above. Figure 9 is a flowchart showing an example of the interlayer waiting process by the additive manufacturing apparatus 100 in Embodiment 2.

[0083] In step S11, the processing head 8 irradiates a laser beam 9 onto a temperature measurement point on the surface of the molded object 15 to form a laser mark 26. During the formation of the laser mark 26, the temperature T of the laser mark formation point rises due to the heat input to the molded object 15 by the laser beam 9. As the temperature T of the laser mark formation point rises, the temperature difference between the temperature T of the laser mark formation point and the surrounding temperature of the laser mark formation point on the molded object 15 increases. As a result, heat dissipation from the laser mark formation point increases, and the rate of temperature increase T per unit time of the laser mark formation point decreases. Step S11 corresponds to the temperature rise process.

[0084] In step S12, the radiation thermometer 17 measures the temperature T of the laser mark formation site after the formation of the laser mark 26. The temperature T of the laser mark formation site is the temperature of the temperature measurement site. After the formation of the laser mark 26, no heat is input to the laser mark 26 by the laser beam 9, so the temperature T of the laser mark formation site gradually decreases. The process in step S12 corresponds to the temperature measurement process. The measurement of the temperature T of the laser mark formation site is performed in the same way as the temperature measurement process described in Embodiment 1 above.

[0085] In step S13, the interlayer waiting time calculation unit 22 calculates the target temperature T of the laser trace formation site after the formation of the laser trace 26, and determines that the fabricated object 15 is at the target temperature T target The cooling time t is the time it takes to cool down to a certain point. wait The cooling time t is calculated and determined. wait This can be called the first interlayer waiting time, which is the interlayer waiting time. The process in step S13 corresponds to the interlayer waiting time determination process. Cooling time t wait The calculation is performed in the same manner as the interlayer waiting time determination process described in Embodiment 1 above. The interlayer waiting time determination process also includes the temperature prediction process described in Embodiment 1.

[0086] In step S14, the additive manufacturing apparatus 100 cools down for a certain period of time t under the control of the NC device 1. wait During this period, the additive manufacturing process is suspended, and inter-layer waiting is performed.

[0087] Next, other additive manufacturing processes using the additive manufacturing apparatus 100 will be described. Figure 10 is a flowchart showing an example of the procedure for other additive manufacturing processes using the additive manufacturing apparatus 100 in Embodiment 2. Figure 11 is a diagram showing an example of the temporal change between the output of the laser beam 9 and the temperature T at the laser trace 26 formation site during the additive manufacturing period of each layer in other additive manufacturing processes using the additive manufacturing apparatus 100 in Embodiment 2. In Figure 11, the time transition of the laser output, which is the output of the laser beam 9, from before the formation of the laser trace 26 to after the formation of the laser trace 26 is shown in the upper characteristic diagram. In the upper characteristic diagram of Figure 11, time t is shown on the horizontal axis and the laser output is shown on the vertical axis. Also in Figure 11, the time transition of the temperature T at the laser trace formation site on the manufactured object 15 from before the formation of the laser trace 26 to after the formation of the laser trace 26 is shown in the lower characteristic diagram. In the lower characteristic diagram of Figure 11, time t is shown on the horizontal axis and the temperature T is shown on the vertical axis.

[0088] First, steps S11 to S14 described above are performed, and then the process proceeds to step S15.

[0089] In step S15, the laser trace 26 is formed again and the interlayer temperature is calculated. That is, the processing head 8 forms the laser trace 26 again at the same temperature measurement location as in step S11, the radiation thermometer 17 measures the temperature T of the laser trace formation location after the formation of the laser trace 26 again in the same manner as in step S12, and the interlayer waiting time calculation unit 22 calculates the temperature of the fabricated object 15, which is the interlayer temperature immediately before the formation of the laser trace 26, and the temperature T of the laser trace formation location immediately before irradiation by the laser beam 9 during the formation of the laser trace 26 again. b The temperature of the fabricated object 15 is calculated and estimated. The temperature of the fabricated object 15 is calculated in the same way as the temperature estimation process described in Embodiment 1 above. Figure 11 shows the time t immediately after irradiation when the laser trace 26 is formed again in step S15. a1 Temperature T immediately after irradiation a1 And, the time immediately before irradiation t b1 Temperature T immediately before irradiation b1 This indicates that. Then proceed to step S16.

[0090] In step S16, the interlayer waiting time calculation unit 22 determines whether the interlayer temperature of the shaped object 15 estimated in step S15 is lower than a temperature reference value which is the value obtained by adding a threshold value ΔT target to the target temperature T th . The threshold value ΔT th is provided in consideration of the measurement error of the radiation thermometer 17. Note that the interlayer waiting time calculation unit 22 may determine whether the interlayer temperature of the shaped object 15 estimated in step S15 is lower than the target temperature T target itself. In this case, the target temperature T target becomes the temperature reference value in step S16.

[0091] The above steps S15 and S16 correspond to a temperature confirmation step in which, after the end of the interlayer waiting, a temperature increase step, a temperature measurement step, and a temperature estimation step are performed, and it is confirmed whether the estimated interlayer temperature of the shaped object 15 has dropped to the target temperature T target .

[0092] In the determination of step S16, if the interlayer temperature of the shaped object 15 estimated in step S15 is lower than the temperature reference value which is the value obtained by adding the threshold value ΔT target to the target temperature T th (step S16, Yes), the process proceeds to step S17. In the determination of step S16, if the interlayer temperature of the shaped object 15 estimated in step S15 is not lower than the temperature reference value which is the value obtained by adding the threshold value ΔT target to the target temperature T th (step S16, No), the process returns to step S13, and steps S13 to S16 are performed again. The repeated steps S13 to S16 correspond to an interlayer waiting time redetermination step for determining a second interlayer waiting time which is the time from after the implementation of the temperature confirmation step to the start of the second laminated shaping step when the temperature at the temperature measurement location estimated in the temperature confirmation step is not less than a predetermined temperature reference value. In the interlayer waiting time redetermination step, when the interlayer temperature of the shaped object 15 estimated in step S15 is not lower than the temperature reference value, the interlayer waiting time can be determined again, and it is possible to wait until the interlayer temperature of the shaped object 15 is lower than the temperature reference value.

[0093] In step S17, the next layer of the build plate is constructed. Then, the process returns to step S11, and the layer construction is repeated.

[0094] Furthermore, the interlayer temperature of the fabricated object 15 estimated in step S15 is equal to the target temperature T target threshold ΔT th If the temperature does not fall below the temperature reference value obtained by adding the values ​​(step S16, No), it is not necessary to repeat steps S13 to S16. For example, return to step S13 and allow the cooling time t wait The value may be recalculated, and then interlayer waiting may be performed again in step S14, followed by the additive manufacturing of the next layer.

[0095] Furthermore, according to the above-described embodiment 2, an additive manufacturing method can be implemented that includes: a beam heat source supply step of irradiating a workpiece with a beam that melts the molding material; a molding material supply step of supplying the molding material to the area of ​​the workpiece irradiated with the beam; a temperature rise step of irradiating a temperature measurement point on the workpiece with a beam after the beam heat source supply step and the molding material supply step have been performed to raise the temperature of the temperature measurement point; a temperature measurement step of measuring the temperature of the temperature measurement point with a thermometer at multiple time series points; and a temperature estimation step of estimating the temperature of the temperature measurement point before the beam is irradiated after the beam heat source supply step and the molding material supply step have been performed, based on the relationship between the multiple time series temperatures, which are the temperatures of the temperature measurement point measured at multiple time series points, and the multiple time series points, or based on the measured temperature measured in the temperature measurement step and the temperature rise value of the workpiece when the beam is irradiated on the workpiece.

[0096] Furthermore, according to the above-described embodiment 2, the additive manufacturing apparatus 100 includes a thermometer that measures the temperature of a temperature measurement point in the object to be measured, which has been preheated, at multiple time series intervals, and a temperature estimation unit that estimates the temperature of the temperature measurement point before the temperature is raised, based on the relationship between the multiple time series temperatures, which are the temperatures of the temperature measurement point measured at multiple time series intervals, and the multiple time series intervals, or based on the measured temperature measured by the thermometer and a predetermined temperature rise value for when the temperature of the object to be measured is raised.

[0097] Furthermore, according to the above-described embodiment 2, the additive manufacturing apparatus 100 is an additive manufacturing apparatus that repeats the process of supplying a manufacturing material to a region of a workpiece irradiated with a beam to form a manufacturing layer, and comprises: a processing head that irradiates a beam onto a temperature measurement point in the manufacturing layer after the manufacturing layer has been formed; a thermometer that measures the temperature of the temperature measurement point at multiple time series points after the beam irradiation; and a temperature estimation unit that estimates the temperature of the temperature measurement point before the beam irradiation after the manufacturing layer has been formed, based on the relationship between the multiple time series temperatures, which are the temperatures of the temperature measurement point measured at multiple time series points, and the multiple time series points, or based on the measured temperature measured by the thermometer and the temperature rise value of the workpiece when the beam is irradiated onto the workpiece.

[0098] In other words, the interlayer waiting time calculation unit 22 incorporates the functions of the temperature estimation unit in the temperature acquisition device 120 and the temperature estimation unit in the additive manufacturing device 100.

[0099] According to Embodiment 2, the additive manufacturing apparatus 100 can measure the temperature of the manufactured object 15 by raising the temperature of the manufactured object 15 at the temperature measurement point by forming a laser trace 26 on the surface of the manufactured object 15, and can estimate the interlayer temperature before the formation of the laser trace 26 from the temperature transition of the manufactured object 15 after the formation of the laser trace 26. As a result, the additive manufacturing apparatus 100 can measure the lowest measurable temperature T of the radiation thermometer 17 in the manufactured material or workpiece. measure_minIt is possible to obtain a temperature in a lower low-temperature range, and based on the obtained temperature, layer manufacturing can be performed, so that the accuracy of layer manufacturing can be improved.

[0100] Also, according to Embodiment 2, after the interlayer standby is completed, the layer manufacturing apparatus 100 checks whether or not the estimated interlayer temperature of the manufactured object 15 has dropped to a temperature lower than a predetermined temperature reference value. That is, the layer manufacturing apparatus 100 irradiates the manufactured object 15 with the laser beam 9 in order to check the temperature of the manufactured object 15 after the interlayer standby, and forms the laser mark 26. Then, the layer manufacturing apparatus 100 estimates the temperature of the manufactured object 15 at the formation location of the laser mark 26 before the formation of the laser mark 26 from the temperature transition at the formation location of the laser mark 26. Thus, the layer manufacturing apparatus 100 can check whether or not the temperature of the manufactured object 15 has dropped to a temperature lower than the temperature reference value after the interlayer standby. As a result, the layer manufacturing apparatus 100 can check that the manufactured object 15 has cooled to a temperature lower than the temperature reference value and perform layer manufacturing of the next layer to be manufactured, and it becomes possible to suppress oxidation or shape collapse of the manufactured object 15.

[0101] Embodiment 3. FIG. 12 is a diagram showing an example of the temperature T before irradiation b immediately before forming the laser mark 26 and the temperature T after irradiation a immediately after forming the laser mark 26, which are obtained by the layer manufacturing apparatus 100 in Embodiment 3. In FIG. 12, the time t is shown on the horizontal axis, and the temperature T at the laser mark formation location is shown on the vertical axis. The measurable minimum temperature T measure_min in FIG. 12 indicates the minimum temperature measurable by the radiation thermometer 17. The temperature rise value ΔT in FIG. 12 is the temperature rise value at the laser mark formation location due to the irradiation of the laser beam 9.

[0102] To measure the temperature of the manufactured object 15, the temperature measurement location is irradiated with the laser beam 9 to form the laser mark 26. The temperature T after irradiation a immediately after forming the laser mark 26 is the temperature T before irradiation bThe temperature rises by a value ΔT due to the heat input from the laser beam 9. The value ΔT of temperature rise is determined by the material 5 of the fabricated object 15, the shape of the fabricated object 15, the location where the laser marks 26 are formed, and the surrounding environment of the fabricated object 15. The value ΔT of temperature rise is expressed by the following equation (6).

[0103]

number

[0104] Figure 13 is a first schematic diagram showing how the additive manufacturing apparatus 100 forms a laser mark 26 on the surface temperature measurement point P of the fabricated object 15 in Embodiment 3. Figure 14 is a second schematic diagram showing how the additive manufacturing apparatus 100 forms a laser mark 26 on the surface temperature measurement point P of the fabricated object 15 in Embodiment 3. Figure 13 shows the laser beam 9 being irradiated onto the surface of the fabricated object 15. Figure 14 shows the laser mark 26 formed on the surface temperature measurement point P of the fabricated object 15 after the laser beam 9 has been irradiated onto the fabricated object 15.

[0105] As shown in Figure 13, a laser beam 9 is irradiated onto a temperature measurement point P, which is a part of the surface of the fabricated object 15. The position of the temperature measurement point P is not limited as long as it is on the surface of the fabricated object 15. For example, the temperature measurement point P can be set to the area where the fabrication of the previous layer in additive manufacturing ended, which is the area with the highest temperature on the surface of the fabricated object 15. As shown in Figure 14, the irradiated laser beam 9 forms a laser mark 26 on the temperature measurement point P, and the temperature rises.

[0106] Next, we will explain how to measure the temperature rise value ΔT. Before actual additive manufacturing in the additive manufacturing apparatus 100, the following process is performed in advance. A laser mark 26 is formed at the temperature measurement point P of the manufactured object 15, and the temperature T immediately before irradiation, just before the formation of the laser mark 26, is measured for the temperature measurement point P. b and the temperature T immediately after irradiation, immediately after the formation of the laser trace 26. a The radiation thermometer 17 is mounted coaxially with the processing head 8 when measuring temperature, so the temperature T immediately before irradiation just before the formation of the laser mark 26 is measured.b is the lowest measurable temperature T measure_min The temperature may fall below this level. For this reason, it is preferable to use a measurement method that can measure from room temperature (20°C) down to the melting point of the molded object 15 by other means. For example, one method is to photograph the molded object 15 with a thermal viewer and measure the temperature of the molded object 15.

[0107] The measured temperature T immediately before irradiation, just before the formation of the laser mark 26. b and the temperature T immediately after irradiation, immediately after the formation of the laser trace 26. a From this, the temperature rise value ΔT is calculated using equation (6). Then, the material 5 of the fabricated object 15, the shape of the fabricated object 15, the temperature measurement location P (the location where the laser mark 26 is formed), and the surrounding environment of the fabricated object 15 are linked to the temperature rise value ΔT and stored in the memory unit 20 of the NC device 1.

[0108] The shape of the fabricated object 15 may be the target shape to be fabricated by the additive manufacturing device 100. The shape of the fabricated object 15 can be stored in a data format that can represent an object, such as a Stereolithography (STL) file or a Polygon File Format (PLY) file. The temperature measurement point P only needs to indicate the coordinates on the surface of the fabricated object 15 where the temperature is to be measured, and may be the coordinates of the 3D points in the PLY file of the fabricated object shape as described above. The surrounding environment includes the chemical composition of the atmosphere and the temperature of the atmosphere.

[0109] Then, for the temperature measurement point P, the material 5 of the molded object 15, the shape of the molded object 15, the temperature measurement point P (the location where the laser mark 26 is formed), and the surrounding environment of the molded object 15 are all changed, the temperature rise value ΔT is calculated, and each condition and the temperature rise value ΔT are linked and stored in the memory unit 20 of the NC device 1.

[0110] When measuring the temperature by forming a laser trace 26 during actual additive manufacturing in the additive manufacturing apparatus 100, the interlayer waiting time calculation unit 22 uses the temperature rise value ΔT stored in the memory unit 20 of the NC device 1, which matches the material 5 of the manufactured object 15, the shape of the manufactured object 15, the temperature measurement location P (location where the laser trace 26 is formed), and the surrounding environment of the manufactured object 15, and the temperature T immediately after irradiation, measured by the radiation thermometer 17, immediately after the formation of the laser trace 26. a From this, using the following equation (7), the irradiation temperature T immediately before the formation of the laser mark 26 can be obtained. b Calculate.

[0111] The temperature T immediately after irradiation, measured by the radiation thermometer 17, which formed the laser trace 26. a From this, using the following equation (7), the irradiation temperature T immediately before the formation of the laser mark 26 can be obtained. b The process of calculating the temperature corresponds to the process of estimating the temperature of the temperature measurement point before the temperature is increased, based on the measured temperature measured in the temperature measurement process and the temperature rise value ΔT of the workpiece when the temperature of the workpiece is increased under predetermined conditions, and can also be said to correspond to the temperature estimation process. Furthermore, the workpiece can be said to be the object of measurement, which is the object whose temperature at the temperature measurement point before the temperature is increased is measured.

[0112]

number

[0113] Note that the temperature rise value ΔT used in equation (7) does not necessarily have to be one in which the material 5 of the fabricated object 15, the shape of the fabricated object 15, the temperature measurement point P (the location where the laser mark 26 is formed), and the surrounding environment of the fabricated object 15 match; a margin of error may be allowed. For example, for the material 5 of the fabricated object 15, it can be considered to match if the main components match. Also, the temperature measurement point can be considered to match if it is within an arbitrarily determined threshold distance from the temperature measurement point P stored in the memory unit 20 of the NC device 1. The surrounding environment can be considered to match if the main components of the atmosphere match. The temperature of the surrounding atmosphere can be considered to match if it is within an arbitrarily determined temperature threshold from the temperature of the surrounding atmosphere stored in the memory unit 20 of the NC device 1.

[0114] According to the above-described embodiment 3, before the additive manufacturing apparatus 100 forms a laser mark 26 on the manufactured object 15 and measures the temperature of the manufactured object 15, data linking the material 5 of the manufactured object 15, the shape of the manufactured object 15, the temperature measurement location P (where the laser mark 26 is formed), the surrounding environment of the manufactured object 15, and the temperature rise value ΔT at the temperature measurement location P due to the laser mark 26 is stored in the storage unit 20 of the NC device 1. Multiple combinations of this data are stored in the storage unit 20 of the NC device 1 by changing the conditions of the material 5 of the manufactured object 15, the shape of the manufactured object 15, the temperature measurement location P (where the laser mark 26 is formed), and the surrounding environment of the manufactured object 15.

[0115] Once the material 5 of the fabricated object 15, the shape of the fabricated object 15, the temperature measurement location P (the location where the laser mark 26 is formed), and the surrounding environment of the fabricated object 15 are determined, it becomes possible to derive the temperature rise value ΔT due to the formation of the laser mark 26.

[0116] This allows for the temperature T immediately after irradiation, which is obtained immediately after the formation of the laser trace 26. a Therefore, by using the above equation (7), the irradiation temperature T immediately before the formation of the laser mark 26 can be determined. bSince this can be calculated, the temperature of the fabricated object 15 can be determined. In addition, by forming the laser trace 26, the temperature of the fabricated object 15 can be increased by the heat input of the laser beam 9, making it possible to measure the temperature of the fabricated object 15 with the radiation thermometer 17 which is coaxial with the processing head 8.

[0117] Next, the hardware configuration of the NC device 1 will be described. The functions of the NC device 1 are realized by the execution of a control program, which is a program for controlling the additive manufacturing device 100, using hardware. In the following description, the program for executing the control method of the additive manufacturing device 100 may be referred to as the control program.

[0118] Figure 15 is a block diagram showing an example of the hardware configuration of the NC device 1 of the additive manufacturing apparatus 100 according to Embodiment 1. The NC device 1 includes a CPU (Central Processing Unit) 201 that performs various processes, a RAM (Random Access Memory) 202 that includes a data storage area, a ROM (Read Only Memory) 203 which is a non-volatile memory, a storage device 204, and an input / output interface 205 for inputting information to and outputting information from the NC device 1. The parts shown in Figure 15 are interconnected via a bus 206.

[0119] The CPU 201 executes the control program stored in the ROM 203 or the storage device 204. Overall control of the additive manufacturing apparatus 100 by the NC device 1 is achieved using the CPU 201.

[0120] The storage device 204 is either an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The storage device 204 stores the condition data table 20a shown in Figure 2. The storage device 204 stores the control program and various data. The ROM 203 stores a boot loader such as a BIOS (Basic Input / Output System) or UEFI (Unified Extensible Firmware Interface), which is the basic control program for the computer or controller that is the NC device 1, and is software or a program that controls the hardware. The control program may also be stored in the ROM 203.

[0121] The programs stored in ROM 203 and storage device 204 are loaded into RAM 202. The CPU 201 loads the control program into RAM 202 and executes various processes. The input / output interface 205 is the interface for connecting the NC device 1 to external devices. Machining programs 18, interlayer temperature data 19, CAD (Computer Aided Design) data, etc., are input to the input / output interface 205. The input / output interface 205 also outputs various commands. The NC device 1 may have input devices such as a keyboard and a pointing device, and output devices such as a display.

[0122] The control program for executing the control method of the additive manufacturing apparatus 100 according to Embodiment 1 may be stored in a storage medium that is readable by a computer. The NC device 1 may store the control program stored in the storage medium in the storage device 204. The storage medium may be a portable storage medium such as a flexible disk, or a semiconductor memory such as flash memory. The control program may be installed from another computer or server device via a communication network to the computer or controller that will become the NC device 1.

[0123] The functions of the NC device 1 may be implemented by a processing circuit, which is dedicated hardware for controlling the additive manufacturing device 100. The processing circuit may be a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. The functions of the NC device 1 may be partially implemented by dedicated hardware and partially implemented by software or firmware.

[0124] The configurations shown in each of the embodiments described above are examples of the content of this disclosure. The configurations of each embodiment can be combined with other known technologies. The configurations of each embodiment may be combined with each other as appropriate. It is possible to omit or modify parts of the configurations of each embodiment without departing from the gist of this disclosure. [Explanation of symbols]

[0125] 1 NC device, 2 Laser oscillator, 3 Fiber optic cable, 4 Material supply device, 5 Material, 6 Gas supply device, 7 Piping, 8 Processing head, 9 Laser beam, 10 Shielding gas, 11 Material nozzle, 12 Head drive device, 13 Stage, 14 Base material, 15 Manufactured object, 16 Protective glass, 17 Radiation thermometer, 18 Processing program, 19 Interlayer temperature data, 20 Storage unit, 20a Condition data table, 21 Program analysis unit, 22 Interlayer waiting time calculation unit, 23 Command value generation unit, 24 Collimating lens, 25 Focusing lens, 26 Laser trace, 100 Additive manufacturing device, 120 Temperature acquisition device, 201 CPU, 202 RAM, 203 ROM, 204 Storage device, 205 Input / output interface, 206 Bus, P Temperature measurement location, t Time, t a ,t a1 Time immediately after irradiation, T a ,T a1 Temperature immediately after irradiation, t b ,t b1 Time immediately before irradiation, T b ,T b1Direct temperature before irradiation, T measure_min Determine the lowest possible temperature, T target Target temperature, t wait Cooling time, ΔT temperature rise value, ΔT th Threshold value.

Claims

1. A beam heat source supply process in which a beam that melts the molding material is irradiated onto the workpiece, A material supply step of supplying the molding material to the area of ​​the workpiece irradiated with the beam, After the beam heat source supply step and the molding material feeding step are performed, a temperature rise step is performed in which the beam is irradiated onto the temperature measurement point on the workpiece to raise the temperature of the temperature measurement point, A temperature measurement step in which the temperature of the temperature measurement location is measured at multiple time points in a series using a thermometer, A temperature estimation step that estimates the temperature of the temperature measurement location before irradiation with the beam after the beam heat source supply step and the molding material supply step are performed, based on the relationship between the multiple time-series temperatures, which are the temperatures of the temperature measurement location measured at multiple time-series times, and the multiple time-series times, or based on the measured temperature measured in the temperature measurement step and the temperature rise value of the workpiece when the beam is irradiated onto the workpiece, A method for additive manufacturing characterized by including [a certain element].

2. The temperature estimation step includes a temperature prediction step of obtaining multiple time-series temperatures at multiple time points and estimating the temperature of the temperature measurement location at a time when the temperature of the temperature measurement location is not measured, based on the relationship between the multiple time points and the multiple time-series temperatures. The additive manufacturing method according to claim 1, characterized by the above.

3. After performing a first additive manufacturing step which includes the beam heat source supply step and the molding material supply step to perform additive manufacturing of a first molding layer on the workpiece, a second additive manufacturing step which includes the beam heat source supply step and the molding material supply step to perform additive manufacturing of a second molding layer on the workpiece, An interlayer waiting time determination step involves obtaining multiple time-series temperatures at multiple time-series times and determining a first interlayer waiting time, which is the time from the end of the first additive manufacturing step to the start of the second additive manufacturing step, based on the relationship between the multiple time-series times and the multiple time-series temperatures. An interlayer waiting process in which the system waits for the duration of the first interlayer waiting time from the end of the first additive manufacturing process until the start of the second additive manufacturing process, The additive manufacturing method according to claim 1, characterized by including the following.

4. The system includes a temperature confirmation step after the interlayer waiting step, in which the temperature rise step, the temperature measurement step, and the temperature estimation step are performed. If the temperature of the temperature measurement location estimated in the temperature confirmation step falls below a predetermined temperature reference value, the second additive manufacturing step is started. The additive manufacturing method according to claim 3, characterized by the above.

5. The process includes an interlayer waiting time re-determination step, which determines a second interlayer waiting time, which is the time from the end of the temperature confirmation step to the start of the second additive manufacturing step, if the temperature of the temperature measurement location estimated in the temperature confirmation step is equal to or greater than a predetermined temperature reference value. The additive manufacturing method according to claim 4, characterized by the above.

6. In the temperature measurement step, the temperature at the temperature measurement location is measured if the temperature has risen to a level above the minimum measurable temperature, which is the temperature that can be measured by the thermometer. A method of additive manufacturing according to any one of claims 1 to 5, characterized by the above.

7. An additive manufacturing apparatus that repeatedly performs the process of supplying a molding material to a region of a workpiece irradiated with a beam to form a molding layer, After the molding layer is formed, a processing head is used to irradiate the temperature measurement point in the molding layer with the beam, A thermometer that measures the temperature of the temperature measurement location at multiple time points in a series after irradiation with the beam, A temperature estimation unit estimates the temperature of the temperature measurement location before the beam is irradiated after the molding layer is formed, based on the relationship between multiple time-series temperatures, which are the temperatures of the temperature measurement location measured at multiple time-series times, and the multiple time-series times, or based on the measured temperature measured by the thermometer and the temperature rise value of the workpiece when the beam is irradiated onto the workpiece. An additive manufacturing apparatus characterized by comprising the following features.

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