JP6844524B2 - Laminated modeling equipment and laminated modeling method - Google Patents

Description

The present invention relates to a laminated molding technique, and relates to a laminated molding control technique using a laser beam and a laminating powder.

One of the laminated molding techniques is laser metal deposition (sometimes referred to as LMD). LMD may be referred to as laser metal deposition, laser powder overlay, and the like. In the LMD method, the laser is scanned while scanning the surface of the base material (sometimes referred to as the base material) and supplying a substance such as a powder metal material (sometimes described as powder metal) and gas to the target location. Irradiate with light. At the location irradiated with the laser beam, the base metal or powder metal melts to form a melt pool. The molten pool solidifies to form a laminate. By repeating such processing for each layer, a structure made of a laminate is laminated on the surface of the base metal.

As a supplement, the molten pool refers to a mixture of the parts where the base metal and powdered metal are melted. Details such as the shape of the molten pool and the degree of melting and solidification differ depending on the physical characteristics of the material, control parameters, and the like. The molten pool may be mixed with other substances in addition to the base metal and powdered metal. In addition to powdered metal, a predetermined gas or other material may be supplied to the laser beam irradiation site.

As a prior art example of the LMD method of laminated molding, as a hardware technology of the laminated molding apparatus, there is a configuration in which a powder metal supply mechanism is built in a laser head provided with a laser light emitting mechanism. Further, as a control technique for laminated molding, there is a technique for performing basic control so as to keep the laser light output (that is, electric power), the amount of powdered metal supplied, and the like constant. In addition, there is a technique for automatically and variably controlling the laser output so as to keep the molten pool area constant.

As an example of the prior art related to the laminated molding of the LMD method, Japanese Patent Application Laid-Open No. 2013-119098 (Patent Document 1) can be mentioned. Patent Document 1 describes that the laser output is controlled according to the distance between the laser head and the object.

Japanese Unexamined Patent Publication No. 2013-119098

In the above-mentioned prior art example regarding the laminated molding of the LMD method, the shape and strength of the laminate are used regardless of whether the control is to keep the laser output constant or to change the laser output so as to keep the molten pool area constant. There is a problem in terms of accuracy and quality. At the time of laminating molding processing, the area of the molten pool and the like may differ in size depending on the result of intentional control or unintended control. The area, depth, height, volume, etc. of the molten pool change depending on the physical properties, shape, amount, etc. of the material. Depending on the size of the molten pool area and the like, the shape of the laminate may collapse, that is, the target shape may not be obtained. For example, when the molten pool area is relatively large with respect to the powder metal supply range, the height of the laminate may be insufficient. Further, for example, when the molten pool area is relatively small with respect to the powder metal supply range, cavities in the laminate and the like occur, leading to internal defects, insufficient strength, and the like. When such shape collapse occurs, it may not be possible to satisfy the predetermined accuracy and quality regarding the shape and strength of the target structure.

An object of the present invention is to improve the accuracy and quality of the shape and strength of a laminate by controlling the laminate molding with respect to the laser powder build-up method of the laminate molding technique using powder for lamination such as powder metal. To provide technology.

A typical embodiment of the present invention is a laminated modeling apparatus or the like, and is characterized by having the following configurations.

The laminated modeling device of one embodiment is a laminated modeling device of a type in which laminating powder is melted and deposited on a base material based on irradiation of laser light, and a control unit that controls laminating modeling and the laser. A laser light emitting mechanism that irradiates light, a powder supply mechanism that supplies the laminating powder, a sensor that detects the area of a molten pool that is a mixture of the base material and the laminating powder, and the base material. The control unit includes a sensor for detecting the specific heat of the laminate, which is a mixture containing the laminating powder, or a specific heat calculation unit for calculating the specific heat, and the control unit sets a control target value of the area of the molten pool according to the specific heat. A laminated molding apparatus having a molten pool control target value calculation unit for calculation and an output control unit for calculating the output value of the laser beam and performing feedback control so as to approach the control target value of the area of the molten pool. is there.

According to a typical embodiment of the present invention, the accuracy and quality of the shape and strength of the laminate can be improved by controlling the laminate molding.

It is a figure which shows the structure of the laminated modeling apparatus of Embodiment 1 of this invention. It is a figure which shows the example of the laminated matter in Embodiment 1. It is a figure which shows the control of the laminated modeling in Embodiment 1. FIG. It is a figure which shows the calculation of the control target value of the molten pool area in Embodiment 1. FIG. It is a figure which shows the control example of the laser light output in Embodiment 1. FIG. It is a figure which shows the structure of the laminated modeling apparatus of Embodiment 2 of this invention. It is a figure which shows the molten metal depth and the height of a laminate in Embodiment 2. FIG. It is a figure which shows the detailed example of the sensor in Embodiment 2. FIG. It is a figure which shows the control of the laminated modeling in Embodiment 2. It is a figure which shows the calculation of the mixing ratio in Embodiment 2. It is a figure which shows the calculation of the specific heat capacity of a laminate in Embodiment 2. It is a figure which shows the mixing ratio and the specific heat of a laminate according to the number of layers in Embodiment 2. FIG. It is a figure which shows the structure of the laminated modeling apparatus of a comparative example. It is a figure which shows the shape collapse in the comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In principle, the same parts are designated by the same reference numerals in all the drawings for explaining the embodiments, and the repeated description thereof will be omitted.

[Problems, etc. (1) -1st control method]
With reference to FIGS. 13 and 14, control issues and the like in the laminated modeling apparatus and method of the prior art example will be supplementarily described.

FIG. 13 schematically shows a configuration in the vicinity of the laser head of the laminated modeling apparatus that performs laminated modeling by the LMD method of the prior art example as a comparative example with respect to the first embodiment. In addition, as explanatory directions, the X direction, the Y direction, and the Z direction are shown. The X direction and the Y direction are two orthogonal directions forming a horizontal plane. The Z direction is the vertical direction.

FIG. 13A shows a state in which the laser head 1 is viewed from the side (Y direction), and the base material 3 and the laminate 5 and the like are shown in a perspective view. As the control of this laminated molding apparatus, basic control for making the laser beam output constant (the first control) or control for making the laser beam output variable so as to make the molten pool area constant (second control). Control) is performed.

The laminated modeling device includes a laser head 1, a drive unit 91, a control unit 90, and the like. An optical fiber or the like is connected to the laser head 1, and as a mounting example, a laser light emitting mechanism and a powder metal supply mechanism are built in. The powder metal supply mechanism may be a mechanism for ejecting and supplying a predetermined gas or other substance in addition to the powder metal.

The control unit 90 controls each part of the laminated modeling apparatus and performs a control process for the laminated modeling. The drive unit 91 drives the laser head 1 based on the drive control from the control unit 90. This drive includes driving the laser beam output and driving the supply of a substance such as powder metal. The laser head 1 is driven by the drive unit 91 based on the control from the control unit 90. Based on the drive, the laser head 1 ejects substances such as powder metal 4 and gas to a target portion on the surface of the base material 3 while emitting laser light 2. Such an operation is called scanning. The direction A1 indicated by the arrow indicates the case of the X direction as an example of the scanning direction. The position coordinates of the target location are indicated by (x, y, z).

FIG. 13B shows an XY plane corresponding to the lower surface of the laser head 1. On the lower surface, the central axis has a laser light emitting surface region 901 by a laser light emitting mechanism, as shown by a circle. A ring-shaped outer peripheral portion outside the laser beam emitting surface region 901 has a powder metal emitting surface region 902 by a powder metal supply mechanism. The laser light 2 is emitted from the laser light emitting surface region 901 toward the target portion downward in the Z direction. At least the powder metal substance is ejected and supplied from the powder metal exit surface region 902 toward the target portion downward in the Z direction.

The lower end of the laser head 1 in the Z direction is at a constant distance (distance Zc) from the main surface 3p of the base material 3. The laser head 1 irradiates the target portion on the surface of the base material 3 with the laser beam 2 by the laser beam emitting mechanism. Further, the laser head 1 supplies the powder metal 4 to the target portion on the surface of the base metal 3 by ejecting the powder metal 4 together with the gas by the powder metal supply mechanism. The control unit 90 controls the irradiation of the laser beam 2 and the supply of the powder metal 4 according to the shape of the target structure, the scanning position, and the like. That is, the control unit 90 controls the on / off of the output of the laser beam 2, the electric power, and the like, and controls the on / off of the ejection of the substance such as the powder metal 4, the supply amount, and the like.

When the laser beam 2 is irradiated, for example, both the base metal 3 and the powder metal 4 are melted to form a molten pool 6 as a mixture thereof. The molten pool 6 may be convex or concave in the Z direction with respect to the main surface 3p of the base metal 3. These depend on physical properties and control details.

The laminated modeling apparatus performs scanning control as a control according to the target structure. That is, the laminated modeling apparatus scans the laser head 1 so as to move in a predetermined direction A1 on the surface of the base material 3. Along with this scanning, the irradiation position of the laser beam 2, the supply position of the powder metal 4, the generation position of the molten pool 6, and the like move in the predetermined direction A1. The movement locus or the like obtained by scanning the laser head 1 may be referred to as a path, a tool path, or the like.

The molten pool 6 made of the base metal 3 or the powder metal 4 or a mixture thereof melted by the irradiation of the laser beam 2 solidifies in response to the passage of the laser beam 2 and the temperature change. As a result, the laminate 5 is formed on the moving loci of the laser head 1 and the molten pool 6. A temperature control mechanism (for example, a cooling mechanism) may be further used for solidification of the molten pool 6.

Similarly, scanning is performed at a predetermined path or position on the XY plane including the Y direction of the base material 3. As a result, the laminate 5 having an area or the like on the XY plane is formed. When the modeling of a certain layer (for example, the first layer) is completed among the plurality of layers in the Z direction, processing is performed in the same manner as above on the XY plane of the next layer (for example, the second layer) above the layer. Will be done. As a result, the laminate 5 corresponding to the layer is formed. Such laminated molding for each layer is similarly repeated as many times as necessary (plurality according to the height of the target structure and the like). The number for identifying the layer currently processed in the Z direction is described as the number of layers N.

For example, when molding the second layer laminate 5 on the first layer laminate 5 (during processing with the number of layers N = 2), a laser is applied to the upper surface of the portion of the first layer laminate 5. Light 2 is irradiated and powder metal 4 and the like are supplied. The molten pool 6 is formed by melting the portion of the laminate 5 and the powdered metal 4.

In the case of the first control method of the laminated molding, even when the laser beam output is constant, the molten pool 6 is caused by the temperature change of the substance such as the base metal 3 while irradiating the target portion with the laser beam 2 during scanning. Area etc. can change. The change in the area of the molten pool causes a change in the shape of the laminate 5 to be formed. As a result, the shape of the laminate 5 may be deformed, that is, a difference may occur with respect to the shape of the target structure. As described above, for example, depending on the size of the molten pool area, the height of the laminate 5 may be insufficient, or the strength may be insufficient due to the internal cavity.

[Problems (2) -Second control method]
In the case of the second control method of laminated modeling, it is as follows. The laminated modeling device of the comparative example to which the second control method is applied detects or calculates the value of the current molten pool area by using a sensor or the like at the time of modeling for each layer. The laminated molding apparatus determines a control target value of the molten pool area so as to keep the molten pool area constant. The laminated molding apparatus performs feedback control that variably controls the laser beam output (that is, electric power) according to the control target value of the molten pool area. That is, the laminated molding apparatus changes the laser beam output value during the subsequent processing so that the actual value of the molten pool area approaches the control target value.

For example, in a laminated molding apparatus, when the actual value (first value) of the molten pool area at the time of modeling a certain layer (for example, the first layer) is larger than the control target value, the laser at the time of the next modeling Decrease the light output value. Further, when the actual value of the molten pool area is smaller than the control target value at the time of modeling a certain layer, the laminated modeling apparatus increases the laser light output value at the time of the next modeling.

However, even when the laser beam output is intentionally controlled so as to keep the molten pool area constant by using the second control method, the shape of the laminate may be deformed. For example, the details of the components (base material 3, powder metal 4, etc.) of the mixture of the molten pool 6 differ depending on the number of layers N and the position coordinates (x, y, z). Therefore, in the portion of the laminate 5 formed by the solidification of the molten pool 6, the internal state and the external state may differ.

In the portion of the laminate 5, the specific heat changes, for example, by mixing the components of the powder metal 4 supplied with respect to the components of the base material 3. The temperature and the mixing ratio of the materials are different for each of the number of layers N and the position coordinates, and the specific heat is different accordingly. Due to the different specific heat, the shape of the laminate 5 may be deformed.

[Problems (3) -Shape collapse]
FIG. 14 schematically shows a difference in the shape and the like of the laminate according to the difference in the molten pool area and the like during the processing of the laminated molding in the comparative example, and an example of the shape collapse. FIG. 14 shows the portions of the base metal 3 and the molten pool 6 on the XZ plane. First, FIGS. 14A and 14B show the case of suitable control and modeling as the first condition. (A) shows a state in which the molten pool 6 is formed by irradiating the laser beam while supplying the powder metal 4 in the predetermined powder metal supply range W11 in the X direction on the surface of the base metal 3. Note that FIG. 14 shows a case where the powder metal supply ranges W11, W12, and W13 are the same under each condition for comparison. The area of the molten pool 6 on the XY plane is indicated by S11 or the like. The area S11 is a suitable case. (B) shows the shape of the laminate 5 after passing through the laser head 1 and after solidification as a result of the control and processing of (A). The height of the laminate 5 in the Z direction is indicated by H11 or the like. In this result, the laminate 5 has a height H11 on the surface of the base material 3 (based on the main surface 3p). The height H11 is preferably in the shape of the laminate 5, that is, in a state close to the target value.

14 (C) and 14 (D) show a case where the molten pool area is larger than that in the case of (A) as the second condition. (C) has a molten pool area S12 with respect to a predetermined powder metal supply range W12. S12> S11. Examples of such factors include various factors such as a case where the laser light output is too large with respect to the melting temperature of the powder metal 4 and the like, and a case where the composition of each layer described later is different. In (D), as a result of (C), the laminate 5 has a height H12 on the surface of the base metal 3. In this state, the height of the laminate 5 is insufficient due to the shape of the laminate 5. The height H12 is insufficient with respect to the height H11 of (B).

14 (E) and 14 (F) show a case where the molten pool area is smaller than that in the case of (A) as the third condition. (E) has a molten pool area S13 with respect to a predetermined powder metal supply range W13. S13 <S11. Examples of such factors include various factors such as a case where the laser light output is too small with respect to the melting temperature of the powder metal 4 and the like, and a case where the composition of each layer described later is different. In (F), as a result of (E), the laminate 5 has a height H13 on the surface of the base metal 3. In this state, a cavity is generated inside as the shape of the laminate 5 is deformed. In addition, dents, cracks, and the like may occur on the outer surface of the laminate 5. The height H13 is excessive with respect to the target height H11 in (B). Further, although the height H13 may be about the same as the height H11, a cavity is generated inside the laminate 5. Therefore, the strength of the laminated product 5 is insufficient with respect to the target value, which may cause crushing or the like.

Further, in the case of the second control method, the laser beam output is variably controlled so that the molten pool area approaches a constant value (for example, the area S11 as a control target value). Even in that case, the temperature and other conditions may differ due to differences in the physical characteristics and composition (mixing ratio, etc.) of the various substances that are the constituent elements of the molten pool 6 and the laminate 5 at the target location to be irradiated with the laser beam. There is. As a result, the shape may be deformed as described above.

As a study by the present inventors, an experiment was conducted in which laminated molding was performed with various settings and controls in which the area of the molten pool was changed to large and small. As a result of the experiment, a difference appeared in the accuracy and quality of the shape of the laminate. For example, when molding was performed so as to have a certain molten pool area (first value), a height deficiency occurred as shown in FIG. 14 (D) as the shape of the laminate collapsed. When molding was performed so as to have another molten pool area (second value), cavities were generated in the laminate as shown in FIG. 14 (F). Depending on the value of the molten pool area, the position, type, degree, etc. of the shape collapse of the laminate differed. From this result, it was found that the accuracy and quality of the shape of the laminate can be improved if the molten pool area is appropriately controlled for modeling.

(Embodiment 1)
The laminated modeling apparatus and method of the first embodiment of the present invention will be described with reference to FIGS. 1 to 5. The laminated modeling device of the first embodiment is an device that performs laminated modeling of the LMD method. The laminated modeling method of the first embodiment is a control method of the laminated modeling of the LMD method, and is a method having steps executed in the laminated modeling apparatus of the first embodiment.

[Overview]
As described above, in the laminated modeling apparatus of the comparative example, the shape of the laminated product 5 may be deformed during processing. Therefore, the laminated modeling apparatus and method of the first embodiment has a device for preventing or suppressing the shape collapse of the laminated product 5 as described below. As a device for this, in the laminated modeling apparatus and method of the first embodiment, unique laminated modeling is controlled. In the laminated modeling apparatus of the first embodiment, specific control is added as the control of the laminated modeling, based on the first control method or the second control method. In the laminated molding apparatus and method of the embodiment, a method of appropriately controlling the molten pool area is used.

The laminated molding apparatus of the first embodiment has a sensor for measuring the area of the molten pool at the target location in real time and a sensor for detecting the specific heat of the laminated portion at the time of laminated molding according to the progress of processing. doing.

The laminated modeling apparatus of the first embodiment determines a suitable control target value of the molten pool area according to the value of its specific heat. That is, in the method of the first embodiment, the control target value itself for appropriately controlling the molten pool area is determined as a value reflecting the specific heat of the laminated portion having the number of layers N. Then, the laminated modeling apparatus of the first embodiment performs feedback control so as to change the laser beam output according to the molten pool area control target value. This feedback control is a control that corrects the detected value, which is an actual value, so as to approach the control target value. Thereby, in this method, the shape collapse of the laminate 5 (the above-mentioned insufficient height, generation of cavities, etc.) is prevented or suppressed.

[Laminate modeling equipment]
FIG. 1 shows a configuration including a laminated modeling apparatus and method of the first embodiment. In FIG. 1, the base material 3 and the like, which are the objects to be processed, are included. The laminated modeling apparatus of the first embodiment includes a laser head 1, an optical fiber unit 1C, a control unit 10, a storage unit 20, a drive unit 30, an input / output setting unit 40, and the like, and these elements are connected to each other. ..

The control unit 10 controls the entire and each part of the laminated modeling apparatus, and executes the control of the laminated modeling. The control unit 10 has a CPU, a ROM, a RAM, and the like. The control unit 10 includes a calculation unit 11. The calculation unit 11 calculates a value for control. The drive unit 30 drives the laser head 1 and the like based on the control from the control unit 10. The drive unit 30 is connected to the optical fiber unit 1C, the laser light emitting unit 1A of the laser head 1, the powder metal supply unit 1B, and the like. The laser head 1 is connected to the optical fiber portion 1C. The laser light emitting unit is an embodiment of the laser light emitting mechanism, and the powder metal supply unit is an embodiment of the powder supply mechanism.

The optical fiber unit 1C and the laser head 1 include a laser light emitting unit 1A and a powder metal supply unit 1B. A laser light emitting portion 1A is mounted on the central axis of the laser head 1, and a powder metal supply portion 1B is mounted on the outer annular portion thereof. The laser light emitting unit 1A emits the laser light 2 from the optical fiber unit 1C toward the target portion below in the Z direction. The powder metal supply unit 1B includes a nozzle or the like, and ejects the powder metal 4 and the gas or the like toward the target portion below in the Z direction. The laminated molding apparatus includes a laser light emitting mechanism including a laser light emitting unit 1A and a powder metal supply mechanism including a powder metal supply unit 1B. The powder metal supply mechanism is a mechanism capable of supplying a predetermined gas or other substance in addition to the powder metal 4.

The laminated modeling apparatus according to the first embodiment is not limited to the configuration of the laser head 1 and the like as shown in FIG. 1, and can be applied to other configurations. For example, a powder metal supply unit may be built in the central axis of the laser head 1, and a laser light emitting unit may be built in the outer peripheral portion. Further, the laser head 1 and the head or nozzle including the powder metal supply unit may be separated and arranged in parallel.

Further, an optical sensor 7 and a specific heat measurement sensor 8 are provided near the side surfaces of the optical fiber portion 1C and the laser head 1. The mounting and method of these sensors are not particularly limited.

The optical sensor 7 is a sensor (melting pond area measuring unit) that detects the area of the molten pool. The optical sensor 7 detects the area of the molten pool (detection value S2 described later) and the like at the target location below in the Z direction during the laminated molding. The detected value of the optical sensor 7 is sent to the calculation unit 11 of the control unit 10 as a detection signal.

The optical sensor 7 detects the molten pool area by an arbitrary method. The optical sensor 7 has, for example, a thermography method, and has a function of measuring the temperature distribution within a predetermined range on three surfaces of the base material including the target portion. In the temperature distribution, the temperature is relatively high in the portion of the molten pool 6 and relatively low in the portion outside the molten pool 6. Therefore, the area of the molten pool 6 can be specified from the temperature distribution, for example, by comparison with the temperature threshold value, and the area of the molten pool can be calculated.

The specific heat measurement sensor 8 measures the specific heat (specific heat Cm of the laminate, which will be described later) of the portion of the laminate 5 formed at the target portion below in the Z direction during the lamination molding. The measured value of the specific heat by the specific heat measurement sensor 8 is sent to the calculation unit 11 of the control unit 10 as a detection signal. The specific heat measurement sensor 8 measures the specific heat by an arbitrary method. For example, the specific heat measurement sensor 8 can measure the specific heat by a laser flash method or the like that irradiates the laminate with a laser pulse light from the opposite side of the sensor using an infrared sensor, but the specific heat may be calculated by another method. ..

The storage unit 20 stores a control program 21, setting information 22, structure data 23, specific heat information 24, and the like. The control unit 10 realizes the control of the laminated modeling by executing the process according to the program 21. The setting information 22 is setting information associated with the program 21, and includes various setting information (including pre-input setting values) used for controlling the laminated modeling. The structure data 23 is data of the target structure, for example, data created by three-dimensional CAD. The specific heat information 24 is publicly known information to be used for measuring the specific heat described later, and is information such as the specific heat for each material substance. As the specific heat information 24, information prepared as a DB in advance may be used. Further, the laminated modeling apparatus may be used for control by referring to various information including the specific heat of the external DB.

The input / output setting unit 40 has an input / output interface for an external device of the laminated modeling device and a user interface for the user. The input / output setting unit 40 includes, for example, an operation panel, a display device, a communication interface device, and the like. The input / output setting unit 40 may be configured by a PC or the like. The input / output setting unit 40 can receive the user's operation input and set the setting information 22 and the like based on the operation input.

The structure data 23 for creating the target laminated model can be created using a three-dimensional CAD system. The structure data 23 is data representing the three-dimensional shape of the structure. The input / output setting unit 40 inputs the structure data 23 and stores it in the storage unit 20. The control unit 10 extracts parameter information such as the number of layers N from the structure data 23. Alternatively, the user may set parameter information such as the number of layers N through the input / output setting unit 40.

Based on the control, the laser head 1 irradiates the target portion of the main surface 3p with the laser beam 2 while moving in the direction A1 according to the scanning on the main surface 3p of the base material 3, and the powder metal 4 and the gas. Etc. are supplied. The powder metal 4 or the like is supplied to the portion irradiated with the laser beam 2. The molten pool 6 is formed by melting the surface of the base metal 3 and the powdered metal 4 and the like by the laser beam 2. The target location (irradiation position of the laser beam 2 and supply position of the powder metal 4) moves with the scanning. The molten pool 6 solidifies due to a temperature change as the irradiation position of the laser beam 2 passes by, and is formed as a laminate 5. That is, the laminate 5 is formed on the moving locus of scanning.

In the first embodiment, as a concept, the molten pool 6 is considered to be a mixture of the base metal 3 and the powder metal 4, and the base metal mixing ratio ε in the mixture is considered. The mixing ratio of the base material 3 and the powder metal 4 varies, and it is assumed that the base material 3 is 100% and the powder metal 4 is 100%. The base material mixing ratio ε is defined as the ratio of the mass (Mp) of the powder metal 4 to the mass (Mb) of the base material 3 (ε = Mb / (Mp + Mb)). The base material mixing ratio ε is a value in the range of 0 to 1 (0 ≦ ε ≦ 1).

The laminated modeling apparatus of the first embodiment shows a case where a part of the laser light emitting mechanism and a part of the powder metal supply mechanism are built in the laser head 1 as in the comparative example, but the present invention is not limited to this. It is possible. The laser light emitting mechanism and the powder metal supply mechanism may be separated as separate devices. Further, for example, a powder metal supply portion may be provided on the central axis of the laser head, and a laser light emitting portion may be provided on the outer peripheral portion. Further, one head may be provided with two or more laser light emitting units and two or more powder metal supply units.

In the laminated modeling apparatus of the first embodiment, the laser head 1 is provided with an optical sensor 7 and a specific heat measurement sensor 8. The details of mounting these sensors are not limited. Various sensors may be built in the laser head 1, or the sensors may be mounted outside the laser head 1. The sensor may move together with the laser head 1, or the sensor may be fixed without moving.

[Example of laminate]
FIG. 2 shows an example of the laminate 5 and the number of layers N. Although the XZ cross section is shown, cross-section hatching and the like are omitted. An example in which a structure consisting of three layers is formed as the laminate 5 on the main surface 3p of the base material 3 is shown. In this laminate 5, the first layer (N = 1) laminate 51, the second layer (N = 2) laminate 52, and the third layer (N = 1) are arranged in this order from the main surface 3p of the base material 3 to the upper layer. It has the laminate 53 of 3). The base material 3 has a path corresponding to the shape of the structure on the XY plane. This path corresponds to the scanning trajectory of the laser head 1. In this example, the layer currently being laminated is the third layer (N = 3), and the molten pool 6 is located at the target location (position below the central axis of the laser head 1 indicated by the alternate long and short dash line) in the laminate 53. Is formed.

[Control parameters]
The parameters (including the case of constant values) handled by the control unit 10 in the first embodiment are as follows. The control unit 10 stores such parameter values in a memory (RAM or the like) or a storage unit 20.

N: Number of layers V: Powdered metal supply amount Cm: Laminate specific heat S1: Control target value of molten pool area S2: Detected value of molten pool area P: Laser light output (electric power).

The number of layers N represents the target layer currently being laminated and modeled in the laminated product 5. It is assumed that the first layer formed by laminating on the three surfaces of the base metal is the first layer (N = 1), and the N value increases in order from the lower layer to the upper layer.

The powder metal supply amount V indicates the supply amount of the powder metal 4 that is ejected from the powder metal supply unit 1B of the laser head 1 to the target location and is supplied.

The number of layers N and the powder metal supply amount V are basic control parameters, and are obtained as one of the structure data 23 or the corresponding setting information 22. Other basic control parameters or setting information include the material to be used, the dimensions of the target structure, and the like.

The specific heat Cm of the laminate is the specific heat of each portion of the laminate 5 (the portion corresponding to the number of layers N and the position coordinates). The specific heat Cm of the laminate is obtained as a value measured by the specific heat measurement sensor 8.

The control target value S1 of the molten pool area is a parameter value that is variably controlled according to the specific heat Cm of the laminate.

The detection value S2 of the molten pool area is an actual value of the area of the molten pool 6 at the target location (the portion corresponding to the number of layers N and the position coordinates) obtained as the detected value by the optical sensor 7.

The laser light output P is the electric power of the laser light 2, and is a parameter value that is variably controlled according to the control target value S1 of the molten pool area.

At the time of control, for example, a threshold value St or the like related to the molten pool area is also used. The threshold value such as the threshold value St or the like may be set in advance as a fixed constant value, or may be set variably by the user through the input / output setting unit 40.

[Control of laminated modeling (laminated modeling method)]
FIG. 3 shows an outline of feedback control of laminated modeling by the control unit 10 in the first embodiment. The control unit 10 uses the number of layers N, the powder metal supply amount V, and the like as basic control parameters. The control unit 10 grasps the number (number of layers N) representing the layer currently being modeled in the plurality of layers in the height direction (Z direction) for laminating the target structure. The control unit 10 makes the control target value different according to the number of layers N.

The control unit 10 counts the number of layers N of the stacking program, and uses the calculation unit 11 to control the number of layers when the number of layers increases, such as calculation 101 of the control target value S1 of the molten pool area and the laser light output P. Calculation 102 is performed. In the control at the first time, a predetermined initial setting value is applied. The control unit 10 drives the laser head 1 based on the calculated and determined laser light output P to execute the laminated modeling at each time. As a result of the state of the laminated molding at each time, the detected value by each sensor is obtained. That is, as the detection value by the optical sensor 7, the detection value S2 of the area of the molten pool 6 at the target location is obtained. Further, as a value measured by the specific heat measurement sensor 8, the specific heat Cm of the laminate 5 of the laminate 5 at the target location can be obtained.

The control unit 10 controls the next time point using the detected value S2 of the obtained molten pool area and the specific heat Cm of the laminate. First, the control unit 10 uses the laminate specific heat Cm as the calculation 101, and calculates the control target value S1 of the molten pool area by the calculation unit 11 (particularly the molten pool control target value calculation unit) based on a predetermined relational expression or the like. Calculate and decide. The control target value S1 is determined as a value proportional to the specific heat Cm of the laminate.

Next, the control unit 10 calculates and determines the laser light output P by the calculation unit 11 (particularly the output control unit) based on a predetermined relational expression or the like using the control target value S1 of the molten pool area. .. In this way, each control is repeated as a feedback control loop.

[Calculation of molten pool area control target value]
As calculation 101, the calculation unit 11 calculates the control target value S1 of the molten pool area based on the detection signal of the specific heat Cm of the laminate. At this time, the control target value S1 of the molten pool area is calculated based on the following equation 1.

S1 = A × Cm ・ ・ ・ Equation 1
As described above, it is as shown in Equation 1 that the control target value S1 is proportional to the specific heat Cm of the laminate. Equation 1 shows that the control target value S1 of the molten pool area is determined by a linear function by multiplying the specific heat Cm of the laminate by a predetermined coefficient A. When Equation 1 is modified, S1 / Cm = A. The coefficient A is a constant value.

FIG. 4 shows a graph showing the relationship between the parameters corresponding to Equation 1. This graph corresponds to the linear function of Equation 1 and is represented by a linear straight line. The horizontal axis is the specific heat of the laminate Cm [J / (kg · K)], and the vertical axis is the control target value S1 [mm ² ] of the molten pool area. The calculation unit 11 determines the control target value S1 based on such a relational expression.

In the method of the first embodiment, the specific heat Cm of the laminate may be different for each portion of the laminate 5 according to the number of layers N and the position coordinates. The control target value S1 of the molten pool area is set as a value different depending on the specific heat Cm of the laminate.

[Calculation of laser light output]
FIG. 5 shows the control of the laser light output P in the control unit 10 and the calculation 102. In the method of the first embodiment, the laser light output P at the next time point is determined by observing the difference between the control target value S1 and the detected value S2 of the molten pool area. When the detected value S2 is larger than a certain value with respect to the control target value S1 of the molten pool area, the control unit 10 reduces the laser light output P at the next time. Similarly, when the detected value S2 is smaller than a certain value with respect to the control target value S1, the control unit 10 increases the laser light output P at the next time point.

In the method of the first embodiment, the variable value of the laser beam output P is calculated using the control target value S1, the detection value S2, and the threshold value St of the molten pool area. In this control example, the variable control value is determined by increasing or decreasing the value by each control with respect to the reference value P0 of the laser light output P. Let it be a positive threshold value St1 and a negative threshold value St2.

The details are as follows. The calculation unit 11 sees the difference value Sd = (S2-S1) of the detection value S2 with respect to the control target value S1 of the molten pool area at a certain time point. When the difference value Sd is equal to or greater than a predetermined positive threshold value St1 (Sd ≧ St1), the calculation unit 11 sets the laser light output P at the next time point as a predetermined unit with respect to the laser light output P at the previous time point. Decrease in quantity or at a given rate. Similarly, when the difference value Sd is equal to or less than a predetermined negative threshold value St2 (Sd ≦ St2), the control unit 10 sets the laser light output P at the next time point with respect to the laser light output P at the previous time point. Increase by a given unit amount or a given rate. In this example, the unit amount Pu is used.

FIG. 5 shows a control example. The horizontal axis represents time and the vertical axis represents laser light output P. The lower side shows the threshold value determination. Initially, the laser light output P has a reference value P0 as an initial value. At the time point t1, Sd = (S2-S1) ≧ St1. Therefore, the control unit 10 changes the laser light output P to a value P1 (= P0-Pu) that is reduced by a predetermined unit amount Pu from the reference value P0. Further, at the time point t2, Sd <St1. Therefore, the control unit 10 changes the laser light output P from the value P1 to a value increased by a predetermined unit amount Pu, that is, returns to the reference value P0. Further, at the time point t3, Sd ≦ St2. Therefore, the control unit 10 changes the laser light output P from the reference value P0 to a value P2 (= P0 + Pu) increased by a predetermined unit amount Pu. Further, at the time point t4, Sd> St2. Therefore, the control unit 10 changes the laser light output P from the value P2 to a value reduced by the unit amount Pu, that is, returns to the reference value P0.

By the variable control of the laser beam output P, the detected value S2 of the molten pool area approaches the control target value S1. As a result, the shape collapse of the laminate 5 is prevented or suppressed. Not limited to the above control example, it is possible. For example, the amount of increase / decrease may be determined at a rate according to the magnitude of the difference value Sd = (S2-S1).

[Effects, etc.]
As described above, according to the first embodiment, the shape collapse of the laminate 5 is prevented or suppressed by the control of the laminated molding of the LMD method, so that the accuracy and quality regarding the shape and strength of the structure are improved. Can be done.

(Embodiment 2)
The laminated modeling apparatus and method of the second embodiment of the present invention will be described with reference to FIGS. 6 to 12. The basic configuration of the second embodiment is the same as that of the first embodiment, and the components different from the first embodiment of the second embodiment will be described below. In the second embodiment, the configuration of the sensor and the calculation processing content of the calculation unit 11 are different. In the second embodiment, a more detailed calculation is performed. In the second embodiment, the specific heat Cm of the laminate is obtained by detailed calculation instead of directly measuring with the specific heat measurement sensor 8.

[Laminate modeling equipment]
FIG. 6 shows the configuration of the laminated modeling apparatus and the like according to the second embodiment. In the laminated modeling apparatus of the second embodiment, the laser head 1 includes an optical sensor 7 and a position sensor 9, but does not include the above-mentioned specific heat measurement sensor 8.

The position sensor 9 detects the depth of the molten pool 6 and the height of the laminate 5 at the target location by an arbitrary method. The detected value of the position sensor 9 is sent to the calculation unit 11 as a detection signal.

The control unit 10 uses the program 21 and the preset input set value (setting information 22) with reference to the number of layers N, the powder metal supply amount V, the base metal specific heat Cb, the powder metal specific heat Cp, and the like (FIG. 9). ..

The calculation unit 11 calculates the specific heat Cm of the laminate using the detected values of the position sensor 9 (depth D of the molten pool, height H of the laminate), the specific heat Cb of the base metal, and the specific heat Cp of the powder metal (FIG. 9).

[Control parameters]
The control parameters (including the case of constant values) handled by the control unit 10 in the second embodiment are as follows. The control unit 10 stores such a parameter value in a memory or a storage unit 20. The parameters common to those in the first embodiment are N, V, Cm, S1, S2, and P.

N: Number of layers V: Powder metal supply amount Cb: Base material specific heat Cp: Powder metal specific heat Cm: Laminate specific heat ε: Mixing ratio (base material mixing ratio)
S1: Control target value of the molten pool area S2: Detected value of the molten pool area D: Depth of the molten pool H: Height of the laminate P: Laser light output (electric power).

In the second embodiment, the base material specific heat Cb, the powder metal specific heat Cp, the mixing ratio ε, the molten pool depth D, and the laminate height H are used. The base material specific heat Cb is the specific heat of the base material 3. The specific heat Cp of the powder metal is the specific heat of the powder metal 4. The base material specific heat Cb and the powder metal specific heat Cp are values according to the material and are obtained as a part of the structure data 23 and the specific heat information 24. The specific heat Cm of the laminate is calculated using those specific heats. The mixing ratio ε indicates the ratio in which the components of the base material 3 are mixed with respect to the total amount of the laminate 5 at the target location. This ratio is roughly expressed as [base material amount] / [total amount] = [base material amount] / ([powder metal amount] + [base material amount]). The molten pool depth D is the depth (length in the Z direction) of the molten pool 6. The height of the laminate H is the height of the laminate 5 (the length in the Z direction). The "amount" of the total amount, the base material amount, and the powder metal amount in the present embodiment is typically a mass.

[Melting pond depth, laminate height]
FIG. 7 shows the concept of the molten pool depth D and the laminate height H. It is shown in the case of the number of layers N = 1. FIG. 7A shows a control target of the molten pool 6 at the target location and the area of the molten pool when the laminate 5 of the first layer (N = 1) is formed on the main surface 3p of the base metal 3. The value S1 (or the detected value S2) and the molten pool depth D are shown. FIG. 7B shows the laminate height H in the portion of the first layer laminate 5 formed by the solidification of the molten pool 6, that is, as a result of the processing of (A).

The concept of the shape of the molten pool 6 includes the case where the shape of the molten pool 6 is as shown in FIGS. 7C and 7D. In FIG. 7C, the molten pool 6 is formed as a convex portion on the main surface 3p or more in the Z direction. The base metal 3 is hardly melted. In this case, the molten pool depth D includes the concept of molten pool height. In FIG. 7D, the molten pool 6 is formed as a downwardly convex portion below the main surface 3p in the Z direction.

[Optical sensor, position sensor]
FIG. 8 shows a detailed example of the optical sensor 7 and the position sensor 9. The optical sensor 7 is, for example, a sensor capable of detecting a temperature distribution state by a thermography method. The optical sensor 7 detects the temperature distribution state in a predetermined range 801 including the target portion below the central axis of the laser head 1. The optical sensor 7 (or the calculation unit 11) identifies the region of the molten pool 6 from the temperature distribution state, and detects the molten pool area (detection value S2).

The position sensor 9 detects the position and shape of the object (melting pond 6 or laminate 5). As the position sensor 9, for example, an optical distance sensor is used. The position sensor 9 irradiates a measurement light toward a target location (irradiation position of the laser beam 2 or a predetermined position behind the laser beam 2), and detects the reflected light. The position sensor 9 measures the round-trip time until the light hits the object and returns, and measures the distance to the object based on the time. The position sensor 9 (or the calculation unit 11) measures the molten pool depth D and the stack height H from the distance and the reference distance Zc (distance between the main surface 3p and the laser head 1). As a method for measuring the depth D of the molten pool, for example, there is a method of measuring and calculating the temperature distribution in the vicinity of the laser irradiation portion with an optical sensor, but the measuring method is not limited thereto.

The melting pond depth D may be detected by the optical sensor 7. Further, the sensor for detecting the depth D of the molten pool and the sensor for detecting the height H of the laminate may be provided separately.

[Control of laminated modeling]
FIG. 9 shows an outline of feedback control of laminated modeling by the control unit 10 in the second embodiment. The control unit 10 uses the number of layers N, the powder metal supply amount V, the base material specific heat Cb, the powder metal specific heat Cp, and the like as basic control parameters. The control unit 10 performs calculation 201 of the mixing ratio ε, calculation 202 of the specific heat Cm of the laminate, calculation 203 of the control target value S1 of the molten pool area, and calculation 204 of the laser light output P as the control at each time. In the control at the first time, a predetermined initial setting value is applied. The control unit 10 drives the laser head 1 based on the calculated and determined laser light output P to execute the laminated modeling at each time.

As a result of the state of laminated modeling at each time, the value detected by each sensor is obtained. That is, as the detection value by the optical sensor 7, the detection value S2 of the molten pool area of the target location is obtained. As the measured values by the position sensor 9, the molten pool depth D and the laminate height H at the target location are obtained.

The control unit 10 controls the next time point using the detected value S2 of the obtained molten pool area, the molten pool depth D, the laminate height H, and the like. First, as calculation 201, the calculation unit 11 calculates the mixing ratio ε based on a predetermined relational expression or the like using the number of layers N and their detected values (S2, D, H).

Next, the specific heat calculation unit of the calculation unit 11 uses the mixing ratio ε, the base material specific heat Cb, and the powder metal specific heat Cp as the calculation 202 to calculate the laminate specific heat Cm based on a predetermined relational expression or the like. calculate.

Next, the molten pool control target value calculation unit of the calculation unit 11 uses the laminate specific heat Cm as calculation 203 as in the first embodiment, and uses a predetermined relational expression to control the molten pool area. Calculate S1.

Next, as calculation 204, the calculation unit 11 determines the laser light output P by a predetermined method using the control target value S1 of the molten pool area as in the first embodiment. In this way, each control is repeated as a feedback control loop.

As described above, the laminated molding apparatus of the second embodiment calculates the mixing ratio ε and the specific heat Cm of the laminated product in the portion of the laminated product 5 actually formed at the time of the laminated modeling of the number of layers N at a certain time point. , Store in memory. The laminated molding apparatus calculates the mixing ratio ε and the specific heat Cm of the laminate using the preset input values (number of layers N, powder metal supply amount V, etc.) and the detected values of the position sensor 9.

The mixing ratio is, for example, the base material mixing ratio, and represents the ratio in which the base material is mixed with respect to the entire laminated portion of interest.

In the laminated molding apparatus of the second embodiment, the control target value of the molten pool area for the control at the next time point is based on the mixing ratio ε of the part of the laminate 5 having the number of layers N at a certain time point and the specific heat capacity of the laminate Determine S1. In other words, the laminated molding apparatus is set so as to change the control target value S1 of the molten pool area according to the change of the mixing ratio ε and the specific heat Cm of the laminate for each portion of the laminate 5 having the number of layers N.

The laminated molding apparatus determines a variable value of the laser beam output P according to the control target value S1 of the molten pool area, and performs feedback control. By repeating such feedback control, the shape collapse of the laminate 5 is prevented or suppressed. As a result, the accuracy and quality of the shape and strength of the structure can be improved.

[Calculation of mixing ratio]
FIG. 10 shows the calculation 202 of the mixing ratio ε in the second embodiment. The graph of FIG. 10 shows the relationship between the mixing ratio ε and the number of layers N. Equation 3 for calculating the mixing ratio ε is also shown on the lower side.

The calculation unit 11 grasps the detected value S2 of the area of the molten pool 6, the depth D of the molten pool, and the height H of the laminate based on the detection signals of the optical sensor 7 and the position sensor 9. Based on these values, the calculation unit 11 calculates the mixing ratio ε of the base metal 3 and the powder metal 4 in the molten pool 6 and the laminate 5 having the number of layers N by the following equation 3.

ε _N = ε _N-1 (1-V / (S2 × (D + H))) ・ ・ ・ Equation 3
The polygonal line in the graph of FIG. 10 shows the mixing ratio ε [%] according to the number of layers N as the relationship based on the equation 3. In Equation 3, the mixing ratio ε is expressed by a recurrence formula. The mixing ratio ε is calculated using the number of layers N, the detected value S2 of the molten pool area, the molten pool depth D, the laminate height H, and the powder metal supply amount V. _{In Equation 3, the mixing ratio ε N} of the portion of the laminate 5 at a certain position (x, y) of a certain layer (number of layers N) is the same position (x, y) of the layer (N-1) immediately below it. ) Is calculated in relation to _{the mixing ratio ε N-1} of the portion of the laminate 5 (or the base material 3). (S2 × (D + H)) roughly indicates the volume of the portion of the molten pool 6 or the laminate 5.

The mixing ratio ε (base material mixing ratio) is roughly represented by [base material amount] / [total amount] = [base material amount] / ([powder metal amount] + [base material amount]).

In the polygonal line of the graph of FIG. 10, the mixing ratio ε becomes a value closer to 0 as the number of layers N increases. The larger the portion of the upper structure 5, the smaller the amount of the base material 3 as the component of the mixture with respect to the amount of the powder metal 4. Therefore, this is the relationship. As described above, since the mixing ratio ε differs depending on the number of layers N, the specific heat Cm of the laminate also differs for each portion of the laminate 5 having the number of layers N.

The calculation unit 11 stores the calculated values such as the mixing ratio ε in the memory or the storage unit 20. For example, the calculation unit 11 updates the value of the mixing ratio ε by using the equation 3 every time the number of layers N increases.

As the laminated modeling device of the modified example, the equation 3 may be simplified and applied by setting an equation such as _{ε N} = ε _{N-1 × B.} The coefficient B is a set value according to the physical properties and detailed control. This equation represents that when calculating the mixing ratio ε of a certain number of layers N, the mixing ratio ε of the layer immediately below it is reflected by the multiplication of the coefficient B. For example, in the first layer, the component of the base material 3 is 50%, in the second layer is 25%, in the third layer is 12.5%, and so on. Becomes smaller.

[Calculation of specific heat of laminate]
FIG. 11 shows the calculation 202 of the specific heat capacity Cm of the laminate according to the second embodiment. The calculation unit 11 determines the portion of the laminate 5 at the target location based on the values of the base material specific heat Cb and the powder metal specific heat Cp, which are preset values, and the value of the mixing ratio ε obtained in the above calculation 201. The specific heat Cm of the laminate is calculated using the following formula 4.

Cm = ε × Cb + (1-ε) × Cp ・ ・ ・ Equation 4
The straight line in the graph of FIG. 11 shows the specific heat Cm [J / (kg · K)] of the laminate corresponding to the mixing ratio ε [%] as a relationship based on the equation 4. As shown in Equation 4, the specific heat Cm of the laminate can be obtained by calculating the combination of the specific heat Cb of the base metal and the specific heat Cp of the powder metal according to the mixing ratio ε. In FIG. 11, the specific heat Cm of the laminate is represented by a linear straight line with the mixing ratio ε as a variable. When considering the layer of the base material 3, the mixing ratio ε = 100% = 1.0 in that layer, and Cm = Cb in the formula 4, for example, Ni-based alloy (718 alloy) is selected as the base material. If so, Cm will be about 450. Further, when considering the upper layer having almost no component of the base material 3, the mixing ratio is ε = 0% = 0 in that portion, and Cm = Cp in the formula 4, for example, when cemented carbide is selected as the powder metal. , Cm is about 250.

[Number of layers, mixing ratio, specific heat of laminate]
FIG. 12 shows, as a supplement to the second embodiment, the mixing ratio ε and the specific heat Cm of the laminate, which differ depending on the number of layers N of the laminate 5. FIG. 12A shows a molten pool 6 and the like at the target location in the laminate 51 of the first layer (N = 1) on the main surface 3p of the base metal 3. In this example, the detected value S2 of the molten pool area is the area S0. In the portion of the molten pool 6, both the base metal 3 and the powder metal 4 have an influence as a mixture. The details also depend on the material and control parameters.

FIG. 12B shows a portion 501 of the laminate 51 as a processing result corresponding to (A). Since this portion 501 is the first layer (N = 1), there are many components of the base material 3, and the mixing ratio ε (base material mixing ratio) is a relatively large value. For example, the ratio of the amount of the base material 3 to the amount of the powder metal 4 in this portion 501 is set on the assumption that [base material amount]: [powder metal amount] = 2: 1. In that case, the mixing ratio ε = ε1 at this point is about 2/3 = 66% from the [base material amount] / [total amount]. Using this mixing ratio ε1, the specific heat Cm1 of the laminate in the portion 501 of the laminate 51 is calculated.

FIG. 12C shows the molten pool 6 in the second layer (N = 2) laminate 52. The molten pool 6 is a portion formed on the portion 501 of the laminate 51 having an area S0 of the first layer. In the portion of the molten pool 6, both the portion 501 of the first layer laminate 51 (the powder metal 4 and the base metal 3 constituting the same) and the supplied powder metal 4 have an influence.

(D) of FIG. 12 shows a portion 502 of the laminate 52 as a processing result corresponding to (C). This portion 502 is formed on the portion 501 of the laminate 51 of the next lower layer. Since this portion 502 is in the upper layer than the portion 501 in the next lower layer, the component of the base material 3 is relatively small. Therefore, the mixing ratio ε (base material mixing ratio) is relatively small as compared with the portion 501. For example, the mixing ratio ε = ε2 (ε _N ) of the portion 502 of the second layer laminate 52 can be calculated by the above formula using the mixing ratio ε1 (ε _{N-1) of the portion 501.} Using this mixing ratio ε2, the specific heat capacity Cm2 of the laminate in this portion 502 can be calculated.

The same is true, but in the melt pond 6 and the laminate 5 portion in each layer having the number of layers N, the characteristics of the portion of the layer immediately below the molten pool 6 have a large influence, and therefore, a predetermined relationship is taken in consideration of the influence. The mixing ratio ε and the specific heat Cm of the laminate can be calculated by the formula. As a result, control using the control target value S1 of the molten pool area that reflects the specific heat Cm of the laminate, which differs depending on the number of layers N, can be realized.

[Effects, etc.]
As described above, according to the second embodiment, the shape collapse of the laminate 5 is prevented or suppressed by the control of the laminated molding of the LMD method, so that the accuracy and quality regarding the shape and strength of the structure are improved. Can be done.

(Modification example)
As the laminated modeling apparatus and method of the modified examples of the first embodiment and the second embodiment, the following control may be further performed. According to experiments and studies by the present inventors, the mixing ratio and specific heat are different, and the degree, type, and details of the shape collapse that occur are also different depending on the molten pool and the part of the laminate having the number of layers N. By appropriately controlling the area of the molten pool and the laser beam output according to the portion of the molten pool and the laminate having the number of layers N, more suitable results can be obtained in terms of the shape and strength of the laminate 5 as a processing result. .. For example, a plurality of layers of the structure may be roughly divided into a plurality of layers such as a lower layer, a middle layer, and an upper layer, and control parameter values may be set to different values in each layer division. Further, in the first and second embodiments, the calculation process of the laser light output P so as to approach the control target value S1 by the control unit 10 is disclosed. However, another calculation may be adopted as the calculation of the laser beam output P that approaches the control target value S1.

As another modification, not only the variable control of the laser beam output but also the variable control of other parameters (for example, the amount of powdered metal supplied) may be added.

Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. For example, the powder metal may be a powder of an alloy (for example, cemented carbide). Further, although the case where the powder metal 4 is used as the laminating powder has been described so far, the laminating powder has (1) a specific heat different from that of the base material, (2) can be melted by laser light, and is a laminating powder. The substance may be any substance having the property that the melt can be mixed with the melt of the base material, and the present invention can be applied to the case of a laminating powder other than the powder metal. Examples of such laminating powders include ceramic powders and cermet powders in addition to the above-mentioned powdered metals. The base material may be any substance having the property of being melted by laser light, and may be ceramics or cermet in addition to metals (including alloys).

1 ... Laser head, 1A ... Laser light emitting part, 1B ... Powder metal supply part, 1C ... Optical fiber part, 2 ... Laser light, 3 ... Base material, 4 ... Powder metal, 5 ... Laminate, 6 ... Molten pond, 7 ... Optical sensor, 8 ... Specific heat measurement sensor, 9 ... Position sensor, 10 ... Control unit, 11 ... Calculation unit, 20 ... Storage unit, 21 ... Program, 22 ... Setting information, 23 ... Structure data, 24 ... Specific heat information , 30 ... Drive unit, 40 ... Input / output setting unit.

Claims (6)

It is a laminating molding device of the type that melts and deposits laminating powder on the base material based on the irradiation of laser light.
A control unit that controls laminated modeling and
A laser light emitting mechanism that irradiates the laser light and
A powder supply mechanism for supplying the laminating powder and
A sensor that detects the area of a molten pool that is a mixture containing at least the base material and the laminating powder, and
A sensor for detecting the specific heat of a laminate, which is a mixture containing at least the base material and the powder for lamination, or a specific heat calculation unit for calculating the specific heat is provided.
The control unit includes a molten pool control target value calculation unit that calculates a control target value of the area of the molten pool according to the specific heat.
A laminated molding apparatus including an output control unit that calculates an output value of the laser beam and performs feedback control so as to approach a control target value of the area of the molten pool. The laminating modeling apparatus according to claim 1, wherein the laminating powder is a powder metal. The laminated molding apparatus according to claim 2, wherein the control unit further includes a position sensor that detects the depth of the molten pool and the height of the laminated product. It is a laminating molding method using a laminating molding device that melts and deposits laminating powder on a base material based on laser light irradiation.
The area of the molten pool is determined from at least the detected value of the area of the molten pool which is a mixture containing the base material and the laminating powder, and at least the specific heat of the laminate which is a mixture containing the base material and the laminating powder. Steps to calculate the control target value and
A step of adjusting the output value of the laser beam to perform feedback control so as to approach the control target value of the area of the molten pool, and
Laminated modeling method. The laminating molding method according to claim 4, wherein the laminating powder is a powder metal. The laminated molding method according to claim 5, wherein the specific heat of the laminate is calculated based on the specific heat of the base material, the specific heat of the powder metal, and the mixing ratio of the base material and the powder metal of the laminate. ..

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