JP2024089144A - Manufacturing method and manufacturing device for molded object - Google Patents

Abstract

To provide a manufacturing method and a manufacturing apparatus of a molded object that can manufacture a molded object into a target shape even for shapes in which it is difficult to manage the lamination height of a weld beads.SOLUTION: A manufacturing method of a molded object includes: an information acquisition process which acquires lamination planning information and target shape information of a molded object 14; an integration index calculation process which calculates an integration index of the lamination shape in which multiple weld beads B are stacked from the welding conditions, bead shape, and lamination trajectory; a welding condition adjustment process which adjusts the welding condition on the basis of the integration index and the target shape information; and a lamination molding process which repeatedly laminates the weld beads B under the acquired welding condition. The welding condition adjustment process corrects at least the welding amount and lamination position included in the welding condition so that the bead width perpendicular to the lamination trajectory approximates the same value in each layer, and the deviation between the integration index and the target shape is reduced.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method and an apparatus for manufacturing a molded object.

In recent years, there has been an increasing need for 3D printers as a means of production, and research and development is being conducted in the aircraft industry, etc., with a view to practical application of 3D printers to metal materials in particular. 3D printers that use metal materials use a heat source such as a laser or arc to melt metal powder or metal wire, and then layer the molten metal to create a model.

Patent Document 1 discloses a manufacturing method in which a weld bead is formed by moving the workpiece or shaped object and the filler torch using NC control so that the weld surface is always at a specified angle and a specified distance is maintained between the filler torch and the weld surface.

JP 2007-275945 A

In additive manufacturing, in which weld beads are stacked to produce a shaped object, it is common to monitor the height of the stacked weld beads and adjust the stacking conditions according to the bead height in order to manage the stacking status of the weld beads.

However, when stacking weld beads in an overhanging shape, adjusting the stacking conditions by focusing only on the height can cause the weld beads to sag, causing the shape of the molded object to deviate from the target shape.

In particular, when weld beads are layered in an arch shape, the overhang angle of the weld bead differs for each pass, so once a positional deviation occurs, the deviation tends to increase thereafter. Similarly, even when weld beads are layered on a smoothly curved surface, the tendency for the weld bead to sag differs depending on the inclination of the curve, so the shape of the molded object is likely to deviate from the target shape.

The present invention aims to provide a manufacturing method and manufacturing device for a molded object that can be molded into a target shape even when the shape is such that it is difficult to control the stack height of the weld beads.

The present invention comprises the following configurations.
(1) A method for manufacturing a shaped object, comprising melting a welding material to form a weld bead, and forming a shaped object by laminating the weld beads, the method comprising the steps of:
an information acquiring step of acquiring lamination plan information including welding conditions, bead shapes, and lamination trajectories of the weld beads to be laminated, and target shape information of a model to be formed;
an integrated index calculation step of calculating an integrated index of a stacking shape in which a plurality of the weld beads are stacked from the welding conditions, the bead shape, and the stacking trajectory;
a welding condition adjustment process for adjusting the welding conditions based on the integrated index and the target shape information;
an additive manufacturing process of repeatedly stacking the weld beads under the acquired welding conditions;
Including,
The welding condition adjustment step includes at least correcting a deposition amount and a layering position included in the welding conditions so that a bead width in a direction perpendicular to the layering trajectory approaches the same value in each layer and a deviation between the integrated index and a target shape is reduced.
A method for manufacturing a sculpture.
(2) An apparatus for manufacturing a shaped object, which melts a welding material to form a weld bead, and manufactures a shaped object by laminating the weld beads, comprising:
an information acquisition unit that acquires lamination plan information including welding conditions, bead shapes, and lamination trajectories of the weld beads to be laminated, and target shape information of a model to be formed;
an integrated index calculation unit that calculates an integrated index of a stacking shape in which a plurality of the weld beads are stacked, based on the welding conditions, the bead shape, and the stacking trajectory;
a welding condition adjustment unit that adjusts the welding conditions based on the integrated index and the target shape information;
an additive manufacturing unit that repeatedly stacks the weld beads under the acquired welding conditions; and
having
the welding condition adjustment unit at least corrects a deposition amount and a layering position included in the welding conditions so that a bead width in a direction perpendicular to the layering trajectory approaches the same value in each layer and a deviation between the integrated index and a target shape is reduced.
Equipment for manufacturing objects.

According to the present invention, it is possible to form an object into a target shape even in cases where it is difficult to control the stack height of the weld beads.

FIG. 1 is a schematic diagram showing the overall configuration of an additive manufacturing system. FIG. 2 is a functional block diagram of the molding control device. FIG. 3 is a flowchart showing a molding procedure performed by the molding control device. FIG. 4 is a schematic diagram showing a model of an arch-shaped object. FIG. 5A is an explanatory diagram showing an example of stacking plan information. FIG. 5B is an explanatory diagram showing an example of stacking plan information. FIG. 5C is an explanatory diagram showing an example of stacking plan information. FIG. 5D is an explanatory diagram showing an example of stacking plan information. FIG. 5E is an explanatory diagram showing an example of stacking plan information. FIG. 6 is a diagram for explaining the influence of correction of the lamination position of the weld bead. FIG. 7 is a schematic diagram showing an integrated index for a model. FIG. 8 is a diagram illustrating a comparison of the lamination state before and after the adjustment of the welding conditions. FIG. 9 is a flowchart showing a molding procedure performed by the molding control device. FIG. 10 is a schematic diagram showing a model of an arch-shaped object. FIG. 11 is a schematic diagram showing bead models of weld beads having different bead widths. FIG. 12 is a schematic diagram of a molded object formed based on a bead model of a weld bead having different bead widths. FIG. 13 is a schematic diagram showing a model of an arch-shaped object after the welding conditions are adjusted. FIG. 14 is a schematic diagram illustrating the formation of a model on an inclined surface. FIG. 15 is a schematic diagram showing the cross-sectional shape of a weld bead when the weld bead is formed along the inclination direction of the inclined surface. FIG. 16 is a schematic diagram showing a shaped object in the case where weld beads having different cross-sectional shapes are laminated. FIG. 17 is a schematic diagram showing a molded object when the welding conditions are adjusted. FIG. 18 is a flowchart showing a modified example of the molding procedure by the molding control device.

The following describes in detail an embodiment of the present invention with reference to the drawings. The additive manufacturing system shown here uses a heat source device to melt a filler material (welding wire) held by a manipulator to form a weld bead, and then repeatedly stacks the formed weld beads into a desired shape to create a model made of stacked weld beads.

<Configuration of additive manufacturing system>
An example of the configuration of an additive manufacturing system that operates based on a trajectory plan determined by the above-mentioned trajectory planning assistance device will be described.
FIG. 1 is a schematic diagram showing the overall configuration of an additive manufacturing system.
The additive manufacturing system 100 is configured to include a manufacturing control device 15, a manipulator 17, a filler material supply device 19, a manipulator control device 21, and a heat source control device 23.

The manipulator control device 21 controls the manipulator 17 and the heat source control device 23. A controller (not shown) is connected to the manipulator control device 21, and any operation of the manipulator control device 21 can be instructed by the operator via the controller.

The manipulator 17 is, for example, a multi-joint robot, and the torch 11 attached to the tip shaft supports the filler material M so that it can be continuously supplied. The torch 11 holds the filler material M protruding from the tip. The position and posture of the torch 11 can be set arbitrarily in three dimensions within the range of the degrees of freedom of the robot arm constituting the manipulator 17. The manipulator 17 is preferably one that has six or more degrees of freedom, and is preferably one that can arbitrarily change the axial direction of the heat source at the tip. The manipulator 17 may be in various forms, such as a multi-joint robot with four or more axes as shown in FIG. 1, or a robot equipped with angle adjustment mechanisms for two or more orthogonal axes.

The torch 11 has a shield nozzle (not shown), and shielding gas is supplied from the shield nozzle. The shielding gas blocks the atmosphere and prevents oxidation and nitridation of the molten metal during welding, thereby suppressing poor welding. The arc welding method used in this configuration may be either a consumable electrode type such as shielded metal arc welding or carbon dioxide gas arc welding, or a non-consumable electrode type such as TIG (Tungsten Inert Gas) welding or plasma arc welding, and is appropriately selected depending on the object to be molded. Here, gas metal arc welding is used as an example. In the case of the consumable electrode type, a contact tip is placed inside the shield nozzle, and a filler material M to which current is supplied is held by the contact tip. The torch 11 generates an arc from the tip of the filler material M in a shielding gas atmosphere while holding the filler material M.

The filler metal supply device 19 supplies the filler metal M toward the torch 11. The filler metal supply device 19 includes a reel 19a on which the filler metal M is wound, and a payout mechanism 19b that pays out the filler metal M from the reel 19a. The filler metal M is fed to the torch 11 by the payout mechanism 19b while being sent in the forward or reverse direction as necessary. The payout mechanism 19b is not limited to a push type that is disposed on the filler metal supply device 19 side and pushes out the filler metal M, but may also be a pull type or a push-pull type that is disposed on a robot arm or the like.

The heat source control device 23 is a welding power source that supplies the power required for welding by the manipulator 17. The heat source control device 23 adjusts the welding current and welding voltage supplied when forming a bead by melting and solidifying the filler metal M. In addition, the filler metal supply speed of the filler metal supply device 19 is adjusted in conjunction with the welding conditions, such as the welding current and welding voltage, set by the heat source control device 23.

The heat source for melting the filler material M is not limited to the arc described above. For example, other heat sources may be used, such as a heating method using both an arc and a laser, a heating method using plasma, or a heating method using an electron beam or a laser. When heating with an electron beam or laser, the amount of heat can be controlled more precisely, and the state of the bead to be formed can be more appropriately maintained, contributing to further improving the quality of the laminated structure. The material of the filler material M is also not particularly limited, and the type of filler material M used may vary depending on the characteristics of the molded object 14, such as mild steel, high-tensile steel, aluminum, aluminum alloy, nickel, or nickel-based alloy.

The molding control device 15 controls all of the above-mentioned parts.

The additive manufacturing system 100 configured as described above operates according to a modeling program created based on a modeling plan for the object 14. The modeling program is composed of a large number of command codes and is created based on an appropriate algorithm according to various conditions such as the shape, material, and heat input of the object. When the torch 11 is moved while the supplied filler material M is melted and solidified according to this modeling program, a linear weld bead B, which is a molten solidified body of the filler material M, is formed on the base plate 13. In other words, the manipulator control device 21 drives the manipulator 17 and the heat source control device 23 based on a predetermined program provided from the modeling control device 15. The manipulator 17 moves the torch 11 while melting the filler material M with an arc according to a command from the manipulator control device 21 to form the weld bead B. In this way, the weld beads B are formed and stacked sequentially to obtain the desired shape of the object 14.

Figure 2 is a functional block diagram of the shaping control device 15. The shaping control device 15 includes an information acquisition unit 31, a welding condition specification unit 33, an integrated index calculation unit 35, and a welding condition adjustment unit 37.

The above-mentioned molding control device 15 is configured by hardware using an information processing device such as a PC (Personal Computer). Each function of the molding control device 15 is realized by a control unit (not shown) reading out a program having a specific function stored in a storage device (not shown) and executing the program. Examples of the storage device include a memory such as a RAM (Random Access Memory) which is a volatile storage area, a ROM (Read Only Memory) which is a non-volatile storage area, and a storage such as a HDD (Hard Disk Drive) and an SSD (Solid State Drive). Examples of the control unit include a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processor Unit), or a dedicated circuit. In addition to the above-mentioned forms, the molding control device 15 may be another computer remotely connected to the additive manufacturing system 100 via a network or the like.

The above-mentioned molding control device 15 performs an information acquisition process, an integrated index calculation process, a welding condition adjustment process, and an additive manufacturing process when stacking the weld beads B to form the object 14.

<Example of modeling procedure>
Next, an example of a procedure for forming the object 14 by the forming control device 15 will be described.
Fig. 3 is a flowchart showing a procedure for forming a structure by the forming control device 15. Fig. 4 is a schematic diagram showing a model of an arch-shaped structure 14. Note that, as shown in Fig. 4, a case in which an arch-shaped structure 14 is formed by stacking weld beads B will be described as an example.

(Information acquisition process)
The information acquisition unit 31 acquires lamination plan information including the welding conditions, bead shape, and lamination trajectory of the weld bead B to be laminated, and target shape information of the shaped object 14 to be formed (step S1).

5A to 5E are explanatory diagrams showing examples of stacking plan information.
As shown in Fig. 5A, the welding conditions for the weld bead B to be stacked include a moving speed Vt when moving the torch 11 to form the weld bead B and a feed speed Vw of the filler metal M. As shown in Fig. 5B, the bead shape includes a bead height ^hv , a bead width ^wH , and a deposition amount Sw of the weld bead B. As shown in Fig. 5C, the stacking trajectory includes a bead stacking position r (r = (x, y, z)) from a stacking start point Ps(i) to a stacking end point Pe(i) where beads are stacked in a specific pass (kth layer), and a stacking trajectory C where a plurality of weld beads B are stacked, each of which is composed of a movement amount Δr (Δr = (Δx, Δy, Δz)) between the stacking start point Ps(i) and the stacking end point Pe(i) and the stacking start point Ps(j) and the stacking end point Pe(j) between passes (between the kth layer and the k+1th layer), as shown in Fig. 5D. As shown in FIG. 5E, the target shape of the object 14 includes an object width W, which is the width dimension, and an object height H, which is the height dimension, of the object 14 to be formed.

(Integrated index calculation process)
Accumulated index calculation unit 35 calculates an accumulated index of a stack shape in which a plurality of weld beads B are stacked, from the welding conditions, the bead shape, and the stacking trajectory (step S2).

In this integrated index calculation step, indices that reflect the progress of the stacked shape, such as height and width, are calculated. Fig. 7 is a schematic diagram showing integrated indices for the shaped object 14. As shown in Fig. 7, the integrated indices are the integrated height Ha, the integrated width Wa, the bead width ^wi⊥c of the upper surface of the weld bead B perpendicular to the stacking direction at the upper end of the shaped object 14, the integrated value Aa of the stacked position, etc., and in the integrated index calculation step, only some of these indices may be calculated. The integrated height Ha, the integrated width Wa, the bead width ^wi⊥c of the upper surface, and the integrated value Aa of the stacked position are calculated by the formulas (1) to (4), respectively.

In addition, as for the bead width w ^{i ⊥c} on the upper surface, if sagging occurs in the weld bead B, the bead width will be narrowed accordingly, and the cumulative effect of the sagging is expressed by the right side of formula (3). Also, the integrated value Aa of the stacking position indicates where it is located on the stacking track C, and may be calculated as a coordinate or as a path length on the stacking track C. Here, in formulas (1) to (3), subscripts are provided to specify in which direction the height and width are defined. In the subscripts, V means vertical, H means horizontal, and ⊥c means perpendicular to the stacking track C. In addition, the same thing can be said about the bead width w i ^⊥c on the upper surface of the bead, but also about the bead width w iu ^⊥c on the lower surface of the bead (see FIG. 7), so the integrated index may be calculated with the bead width w iu ^⊥c on the lower surface of the bead. However, since the bead width w iu ^⊥c of the lower surface of the bead is evaluated from the stack after the upper and lower weld beads B have fused together, and the bead width w i ^⊥c of the upper surface of the bead can be measured directly before it is fused with the upper weld bead B, it is more preferable to evaluate formula (7) using the bead width w i ^⊥c of the upper surface of the bead when the welding conditions are corrected successively during manufacturing. For example, it becomes difficult to measure the bead width w iu ^⊥c of the lower surface of the bead with a laser sensor when the inclination in the stacking direction becomes steep, but the bead width w i ^⊥c of the upper surface of the bead can be measured with a laser sensor other than a camera.

(Welding condition adjustment process)
The welding condition adjustment unit 37 adjusts the welding conditions based on the integrated index and the target shape information. In the above-mentioned welding condition adjustment process, the welding condition adjustment unit 37 corrects at least the deposition amount and the lamination position included in the welding conditions so that the bead width in the direction perpendicular to the lamination trajectory C approaches the same value in each layer and the deviation between the integrated index and the target shape is reduced (step S3).

Equations (5) to (7) are used to adjust the welding conditions, and the adjusted index (desired solution) of equation (8) is derived from these equations (5) to (7). Note that equation (8), which is the adjusted index, is distinguished by the addition of a hat symbol.

Equation (5) takes into account height adjustment, and equation (6) takes into account width adjustment. In equations (5) and (6), when the weld bead B is layered at an angle, like an overhang, the height and width do not simply increase compared to when it is layered vertically, so the effect of the inclination is expressed by R1 and R2. In the simplest case, the inclination α from the horizontal can be expressed by cosα or sinα. Meanwhile, the term in brackets { } on the right hand side of equations (5) and (6) is a term that represents the deviation between the integrated index and the target shape, and the denominator n or the weld position r can be changed depending on this deviation.

Equation (7) imposes a condition that the bead width of each layer can be considered to be substantially constant. Of course, when the weld bead B is layered at an angle, such as in an overhang, the width tends to decrease as the bead sags to the side in proportion to the angle, and this effect is expressed by the second term on the middle side. Furthermore, the first term on the middle side of equation (7) indicates that the bead width increases or decreases with the amount of deposition. For example, a regression equation for the function θ may be created from an experiment that examines the correlation between the direction of inclination, the amount of deposition, and sagging. Furthermore, the function Λ may also be experimentally determined, similar to the function θ. Furthermore, a predetermined allowable variation value is set on the right and left sides of equation (7) for the bead width, which is a predetermined constant.

Figure 7 is a diagram explaining the effect of correcting the layering position of weld bead B. In Figure 7, Pa represents the bead layering position before correction, and Pb represents the bead layering position after correction. Figure 7 shows that correcting the bead layering position of the i-th layer changes the increase in height and width.

(Additive manufacturing process)
Thereafter, the weld beads B are repeatedly laminated under the adjusted welding conditions to form the object 14 (step S4).

FIG. 8 is a diagram illustrating a comparison of the lamination state before and after the adjustment of the welding conditions.
The left side of FIG. 8 shows a state where a weld bead B is formed at a target position Pa that does not take into account the influence of the sagging of the weld bead B and is stacked as a unit along the stacking direction. In this state, the upper surface width of the bead of the lower layer does not match the lower surface width of the bead of the upper layer, and sagging actually occurs. The center of FIG. 8 shows a state where a weld bead B is formed at a target position Pb that takes into account the influence of the sagging of the weld bead B, and the deposition amount and the stacking position are corrected so that the upper surface width of the bead of each layer approaches the same value. In this example, since the upper layer is more likely to sag, the deposition amount is smaller in the upper layer and larger in the lower layer. The right side of FIG. 8 shows the stacking position when the influence of the sagging of the weld bead B is not taken into account (left side of FIG. 8) and the stacking position when the influence of the sagging of the weld bead B is taken into account (center of FIG. 8), and the stacking position is corrected so that the final stacking shape matches the target shape. In this way, according to the manufacturing method of this configuration example, it is possible to form a molded object having a shape that is difficult to manage the stacking shape because of an overhang, into a target shape.

<Example of application of modeling procedure for objects>
Next, an application example of the molding procedure of the molding control device 15 for forming the object 14 will be described.
FIG. 9 is a flowchart showing a procedure for forming an object by the forming control device 15.
Fig. 10 is a schematic diagram showing a model of arch-shaped object 14. Fig. 11 is a schematic diagram showing bead models BM of weld beads B with different bead widths BW. Fig. 12 is a schematic diagram of object 14 formed based on bead models BM of weld beads B with different bead widths BW. Fig. 13 is a schematic diagram showing a model of arch-shaped object 14 after adjustment of welding conditions.

The information acquisition unit 31 acquires stacking plan information including the reference width Bw as the bead shape of the weld bead B to be stacked, and target shape information of the object 14 to be formed (step S11).

For example, as shown in FIG. 10, when forming an arch-shaped object 14, trapezoidal bead models BM of the same shape, equally divided, are assigned and positioned on the object 14. Then, by adjusting the size of this bead model BM, a bead model BM that satisfies the target shape to be formed (black solid line in FIG. 10) is created, and a reference width BWb, which is the reference bead width BW of this bead model BM, is obtained. This reference width BWb is the dimension of the bead model BM in a direction perpendicular to the stacking direction DL of the weld bead B.

As a method of allocating the weld bead B to the shaped object 14, for example, the shape of the loaded three-dimensional shape data (CAD data, etc.) of the shaped object 14 is sliced in a direction perpendicular to the layering direction DL of the weld bead B, and further divided into rectangular bead models BM corresponding to the bead shape of the weld bead B. Then, the divided rectangular bead models BM are fitted to a trapezoid, which is a simple geometric figure, and changed into trapezoidal bead models BM.

The welding condition specification unit 33 specifies the welding conditions for forming a weld bead B with a deposition amount that satisfies the standard width BWb (step S12). The deposition amount of each weld bead B is adjusted according to the stacking direction DL and number of layers of the weld bead B. When adjusting, the bead width BW of each weld bead B is restricted so as to satisfy the standard width BWb. Note that the welding conditions may be specified directly from the stacking plan.

Here, as shown in Figures 11 and 12, when weld beads B1 and B2 are alternately stacked based on bead models BM1 and BM2 with different bead widths BW1 and BW2, weld bead B2 with a bead width BW2 wider than weld bead B1 is likely to sag at the protruding portions at both ends. In this way, when weld beads B1 and B2 are stacked using bead models BM1 and BM2 with different bead widths BW1 and BW2, not only is the stacking height not met, but the overall shape may significantly deviate from the target shape. This phenomenon is likely to occur, for example, when weld beads B are stacked on a base plate 13 with an inclined surface. When the base plate 13 has an inclined surface, the bead width BW is narrow in the upward weld bead B formed upward in the inclination direction, and the bead width BW is wide in the downward weld bead B formed downward in the inclination direction. In other words, deviation of the shape of the shaped object 14 from the target shape is likely to occur when upward weld beads B and downward weld beads B are layered alternately.

For this reason, the welding condition specification unit 33 creates a bead model BM in which the bead width BW of each weld bead B is adjusted to the reference width BWb while adjusting the deposition amount of the weld bead B. Ideally, the bead width BW of the bead model BM of each weld bead B is a constant value, but a minute tolerance value α may be set to adjust the deposition amount so that the bead width BW falls within ±α of the reference width BWb.

When the bead width BW of the weld bead B of the bead model BM is adjusted to the reference width BWb with priority, the deposition amount and bead height may differ for each weld bead B. The welding condition specification unit 33 calculates the welding conditions for each weld bead B while allowing for such differences in the deposition amount and bead height for each weld bead B.

The specific method of calculating the welding conditions is not particularly limited, but for example, a formula that is modeled based on representative parameters of the welding conditions may be prepared, and the conditions may be adjusted based on the formula.

For example, the bead height BH may be calculated from equation (9), and the bead width BW may be calculated from equation (10).
BH = C1 + C2Wf + C3Ts + C4Wf2 + C5Ts2 + C6WfTs ... formula (9)
BW=D1+D2Wf+D3Ts+D4Wf2+D5Ts2+D6WfTs ... Equation (10)
Ts: Torch travel speed Wf: Filler metal feed speed C1 to C6: Coefficients D1 to D6: Coefficients

The integrated index calculation unit 35 calculates the integrated height Ha of the height of the weld bead B to be stacked as an integrated index from the welding conditions, the reference width BWb of the bead shape, and the stacking trajectory (step S13). In other words, the integrated height Ha is the height dimension consisting of the vertical dimension of the shaped object 14 on which the weld bead B is stacked. The integrated height Ha may also be calculated as the length of a curved line segment along the stacking direction DL of the weld bead B.

The welding condition adjustment unit 37 adjusts the welding conditions based on the integrated height Ha, which is an integrated index, and the target shape information (step S14). Specifically, the integrated height Ha calculated by the integrated index calculation unit 35 is compared with the target height Ht based on the target shape information. Then, it is determined whether the deviation between the integrated height Ha and the target height Ht (|Ha-Ht|) is within a predetermined variation tolerance ε.

When the welding condition adjustment unit 37 determines that the deviation between the integrated height Ha and the target height Ht exceeds the variation tolerance ε (step S14: No), it adjusts the welding conditions identified by the welding condition identification unit 33 to welding conditions in which the number of passes or the deposition amount of the weld bead B is changed (step S15). In adjusting the welding conditions, for example, at least one of the number of passes of the weld bead B that forms the object 14 and the distribution of the bead height BH of each weld bead B is adjusted.

For example, when forming an arch-shaped object 14 (see FIG. 10), as shown in FIG. 13, the deposition amount of the weld bead B is increased as the stacking direction DL becomes closer to vertical, while the deposition amount of the weld bead B is decreased as the inclination becomes greater. The welding conditions and number of passes for each weld bead B may be adjusted based on the bead width BW and aspect ratio of the portion that can be realized with one weld bead B. For example, in areas where the weld bead B is prone to sagging, the number of passes may be increased to reduce the deposition amount per weld bead B and adjust the welding conditions to reduce the aspect ratio.

These welding conditions can be relatively easily adjusted by, for example, any one or a combination of the angle of the torch 11 that forms the weld bead B, the welding speed of the weld bead B, the feed speed of the filler metal M fed to the torch 11, the welding current of the weld bead B, the welding voltage of the weld bead B, the operating direction of the torch 11, and the weaving conditions of the torch 11.

Then, when the welding condition adjustment unit 37 determines that the deviation between the integrated height Ha and the target height Ht is within the variation tolerance ε (step S14: YES), it maintains the welding conditions identified or adjusted by the welding condition identification unit 33, and then repeatedly stacks the weld beads B under these welding conditions to form the object 14 (step S16).

In this way, according to the manufacturing method of the shaped object 14 of this configuration example, by stacking the weld beads B with a priority on uniformity of the bead width BW, it is possible to suppress sagging of the weld beads B when stacking the weld beads B, and the stacking height of the shaped object 14 can be easily adjusted.

In addition, when adjusting the bead width BW, the deposition amount and bead height BH of each weld bead B are not fixed, so the welding conditions can be flexibly adjusted according to the layering location and layering position, making it possible to shape overhanging parts and achieve good layering on inclined surfaces in particular.

Next, an application example of the method for forming a model by the above-mentioned model-forming control device 15 will be described.
Fig. 14 is a schematic diagram for explaining the formation of object 14 on inclined surface Si. Fig. 15 is a schematic diagram showing the cross-sectional shape of weld bead B when weld bead B is formed along the inclination direction of inclined surface Si. Fig. 16 is a schematic diagram showing an object when weld beads B with different cross-sectional shapes are laminated. Fig. 17 is a schematic diagram showing object 14 when the welding conditions are adjusted.

As shown in FIG. 14, in this application example, the base plate 13 has an inclined surface Si that is inclined at an inclination angle θa with respect to the horizontal plane, and the weld beads B are layered on this inclined surface Si to form the shaped object 14. The weld beads B are formed in an upward inclination direction Du and a downward inclination direction Dd with respect to the inclined surface Si. In other words, the upward weld beads Bu formed toward the upward inclination direction Du and the downward weld beads Bd formed toward the downward inclination direction Dd are layered alternately on the inclined surface Si. In this way, by layering the upward weld beads Bu and the downward weld beads Bd alternately on the inclined surface Si, the torch 11 can be turned back between each pass, thereby reducing the amount of movement of the torch 11 and improving productivity.

However, as shown in FIG. 15, when a weld bead B is formed on an inclined surface Si along the inclination direction, the upward weld bead Bu and the downward weld bead Bd are formed with a different aspect ratio in cross section compared to a normal weld bead Bf when formed on a horizontal surface.

As a result, as shown in FIG. 16, when upward weld beads Bu and downward weld beads Bd are alternately layered on an inclined surface Si (right side in FIG. 16), a discrepancy occurs in the shape and build height compared to when weld beads Bf are layered on a horizontal surface (left side in FIG. 16).

In such a case, the welding conditions for each weld bead Bu, Bd are adjusted so that the bead width BW of the upward weld bead Bu and the downward weld bead Bd is such that the deposition amount satisfies the reference width BWb obtained from the reference bead model (steps S12 to S15). For example, by adjusting the welding speed, the deposition amount when forming the upward weld bead Bu is increased and the deposition amount when forming the downward weld bead Bd is decreased. Then, as shown in FIG. 17, when the weld bead Bf is layered on a horizontal surface (left side in FIG. 17), the weld beads Bu, Bd can be layered in a balanced manner and the shape and height of the weld bead can be approximated even when the upward weld bead Bu and the downward weld bead Bd are alternately layered on the inclined surface Si (right side in FIG. 17).

Next, a modified example will be described.
The same components as those in the above example are designated by the same reference numerals and their description will be omitted.
FIG. 18 is a flowchart showing a modified example of the molding procedure by the molding control device 15.

As shown in FIG. 18, in the modified example, when the weld bead B is formed and layered (step S16), the shape of the in-process object 14 is measured by a shape measurement sensor to obtain a shape profile (step S17). Note that the shape measurement sensor may be installed in parallel with the torch 11 on the tip axis of the manipulator 17, or may be installed separately from the manipulator 17.

Then, based on this acquired shape profile, the bead width BW and stacking height of the stacked weld beads B are extracted. Furthermore, by referring to the information on the bead width BW and stacking height, the reference width BWb and cumulative height Ha are monitored during the manufacturing process, and the welding conditions are adjusted as necessary. For example, the bead width BW may be monitored and the welding conditions corrected in real time so that it does not fall below the reference width BWb. Furthermore, after correcting the reference width BWb with the bead width BW obtained by shape measurement, the cumulative height Ha may be compared with the target height Ht, and the welding conditions, such as the feed speed of the filler material M, the welding speed of the weld bead B, and the presence or absence of weaving, may be adjusted again during the manufacturing process.

According to this modified example, the cumulative height Ha is corrected from the shape profile obtained by shape measurement based on the shape of the object 14 in the process of being manufactured, so that the cumulative height Ha can be compared more accurately with the target shape, and as a result, the welding conditions can be adjusted with high precision.

As such, the present invention is not limited to the above-described embodiments, and the invention also contemplates combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known technologies, and these are included in the scope of the protection sought.

As described above, the present specification discloses the following:
(1) A method for manufacturing a shaped object, comprising melting a welding material to form a weld bead, and forming a shaped object by laminating the weld beads, the method comprising the steps of:
an information acquiring step of acquiring lamination plan information including welding conditions, bead shapes, and lamination trajectories of the weld beads to be laminated, and target shape information of a model to be formed;
an integrated index calculation step of calculating an integrated index of a stacking shape in which a plurality of the weld beads are stacked from the welding conditions, the bead shape, and the stacking trajectory;
a welding condition adjustment process for adjusting the welding conditions based on the integrated index and the target shape information;
an additive manufacturing process of repeatedly stacking the weld beads under the acquired welding conditions;
Including,
The welding condition adjustment step at least corrects the deposition amount and the layer position included in the welding conditions so that the bead width in the direction perpendicular to the layering trajectory approaches the same value for each layer and the deviation between the integrated indicator and a target shape is reduced.
According to this method for manufacturing a molded object, by stacking the weld beads with a priority on uniformity of bead width, it is possible to suppress sagging of the weld beads when stacking the weld beads, and the stacking height of the molded object can be easily adjusted.
In addition, when adjusting the bead width, the deposition amount and bead height of each weld bead are not fixed, so the welding conditions can be flexibly adjusted according to the stacking location and stacking position, making it possible to achieve particularly good shaping of overhanging parts and stacking on inclined surfaces.

(2) The method for manufacturing a shaped object according to (1), wherein the welding condition adjustment step involves adjustment of any one or a combination of an angle of a torch that forms the weld bead, a welding speed of the weld bead, a feed speed of a filler metal fed to the torch, a welding current of the weld bead, a welding voltage of the weld bead, a rod operating direction of the torch, and a weaving condition of the torch.
According to this method for manufacturing a shaped object, the deposition amount, bead width, and aspect ratio of the weld bead can be adjusted relatively easily.

(3) The method for manufacturing a shaped object according to (1) or (2), wherein the welding condition adjustment step corrects the number of layers by decreasing the deposition amount and increasing the number of layers.
According to this method for manufacturing a molded object, by increasing the number of layers, it is possible to fine-tune the height and width of the laminated shape, making it easier to approximate the laminated shape to a target shape.

(4) The method further includes a shape profile acquisition step of measuring a shape of the laminated weld bead to acquire a shape profile,
The manufacturing method of a molded object according to any one of (1) to (3), further comprising correcting the integrated index based on the acquired shape profile.
According to this method for manufacturing a molded object, the integrated index is corrected based on the shape profile obtained by shape measurement, so that the integrated index can be compared more accurately with the target shape, and as a result, the welding conditions can be adjusted with higher accuracy. Also, during the lamination of the weld beads, the welding conditions can be adjusted and corrected based on the shape of the molded object in the process of being manufactured.

(5) The method for manufacturing a shaped object according to any one of (1) to (4), wherein the welding condition adjustment step includes adjusting the welding condition so that the deposition amount is decreased as the inclination angle of the lamination direction of the weld beads with respect to a vertical direction increases.
According to this manufacturing method for a molded object, for example, in a location where the inclination of the lamination direction of the weld beads with respect to the vertical direction is large and it is difficult to obtain a sufficient lamination height and the amount of sagging is likely to occur, the amount of deposition of the weld beads can be reduced to suppress the amount of sagging. Also, in a location where the inclination with respect to the vertical direction is small and sagging is difficult, the amount of deposition of the weld beads can be increased to efficiently mold the object.

(6) A method for manufacturing a shaped object according to any one of (1) to (5), in which upward weld beads formed in an upward direction of the inclination and downward weld beads formed in a downward direction of the inclination are alternately layered on an inclined surface.
According to this method for manufacturing a shaped object, by alternately stacking upward weld beads and downward weld beads, the amount of torch movement between passes can be shortened, thereby improving productivity.

(7) The method for manufacturing a shaped object according to (6), wherein in the welding condition adjustment step, a deposition amount of the upward weld bead is increased and a deposition amount of the downward weld bead is decreased.
According to this method for manufacturing a structure, by increasing the amount of deposition of the upward weld bead and decreasing the amount of deposition of the downward weld bead, the weld beads can be layered in a balanced manner, and a structure closer to the target shape can be produced.

(8) An apparatus for manufacturing a shaped object, the apparatus melting a welding material to form a weld bead, and forming a shaped object by laminating the weld beads, comprising:
an information acquisition unit that acquires lamination plan information including welding conditions, bead shapes, and lamination trajectories of the weld beads to be laminated, and target shape information of a model to be formed;
an integrated index calculation unit that calculates an integrated index of a stacking shape in which a plurality of the weld beads are stacked, based on the welding conditions, the bead shape, and the stacking trajectory;
a welding condition adjustment unit that adjusts the welding conditions based on the integrated index and the target shape information;
an additive manufacturing unit that repeatedly stacks the weld beads under the acquired welding conditions; and
having
the welding condition adjustment unit at least corrects the deposition amount and the layer position included in the welding conditions so that the bead width in the direction perpendicular to the layering trajectory approaches the same value for each layer and the deviation between the integrated indicator and a target shape is reduced.
According to this object manufacturing apparatus, by stacking the weld beads with a priority on uniformity of bead width, it is possible to suppress sagging of the weld beads when stacking the weld beads, and the stacking height of the object can be easily adjusted.
In addition, when adjusting the bead width, the deposition amount and bead height of each weld bead are not fixed, so the welding conditions can be flexibly adjusted according to the stacking location and stacking position, making it possible to achieve particularly good shaping of overhanging parts and stacking on inclined surfaces.

REFERENCE SIGNS LIST 11 Torch 14 Modeled object 31 Information acquisition unit 35 Accumulation index calculation unit 37 Welding condition adjustment unit 100 Additive manufacturing system (additive manufacturing unit, manufacturing device)
B Weld bead Bu Upward weld bead Bd Downward weld bead Ha Accumulated height (accumulation index)
Ht target height Si inclined surface

Claims (8)

A method for manufacturing a shaped object, comprising melting a welding material to form a weld bead, and forming a shaped object in which the weld beads are laminated, the method comprising the steps of:
an information acquiring step of acquiring lamination plan information including welding conditions, bead shapes, and lamination trajectories of the weld beads to be laminated, and target shape information of a model to be formed;
an integrated index calculation step of calculating an integrated index of a stacking shape in which a plurality of the weld beads are stacked from the welding conditions, the bead shape, and the stacking trajectory;
a welding condition adjustment process for adjusting the welding conditions based on the integrated index and the target shape information;
an additive manufacturing process of repeatedly stacking the weld beads under the acquired welding conditions;
Including,
The welding condition adjustment step corrects a deposition amount and a layering position included in the welding conditions so that a bead width in a direction perpendicular to the layering trajectory approaches the same value in each layer and a deviation between the integrated index and a target shape is reduced.
A method for manufacturing a sculpture. The welding condition adjustment step involves adjusting any one or a combination of an angle of a torch forming the weld bead, a welding speed of the weld bead, a feed speed of a filler metal fed to the torch, a welding current of the weld bead, a welding voltage of the weld bead, a rod operating direction of the torch, and a weaving condition of the torch.
The method for producing a shaped object according to claim 1 . The welding condition adjustment step corrects the number of layers so as to reduce the deposition amount and increase the number of layers.
The method for producing a shaped object according to claim 1 . The method further includes a shape profile acquisition step of measuring the shape of the laminated weld bead to acquire a shape profile,
correcting the integrated index based on the acquired shape profile;
The method for producing a shaped object according to claim 1 . In the welding condition adjustment step, the welding amount is adjusted to be smaller as the inclination angle of the lamination direction of the weld beads with respect to the vertical direction increases.
The method for producing a shaped object according to claim 1 . On the inclined surface, upward weld beads formed in an upward direction in the inclination direction and downward weld beads formed in a downward direction in the inclination direction are alternately laminated.
The method for producing a shaped object according to any one of claims 1 to 5. In the welding condition adjustment step, a deposition amount of the upward weld bead is increased and a deposition amount of the downward weld bead is decreased.
The method for producing a shaped object according to claim 6 . An apparatus for manufacturing a shaped object, the apparatus melting a welding material to form a weld bead and forming a shaped object in which the weld beads are laminated, comprising:
an information acquisition unit that acquires lamination plan information including welding conditions, bead shapes, and lamination trajectories of the weld beads to be laminated, and target shape information of a model to be formed;
an integrated index calculation unit that calculates an integrated index of a stacking shape in which a plurality of the weld beads are stacked, based on the welding conditions, the bead shape, and the stacking trajectory;
a welding condition adjustment unit that adjusts the welding conditions based on the integrated index and the target shape information;
an additive manufacturing unit that repeatedly stacks the weld beads under the acquired welding conditions; and
having
the welding condition adjustment unit at least corrects a deposition amount and a layering position included in the welding conditions so that a bead width in a direction perpendicular to the layering trajectory approaches the same value in each layer and a deviation between the integrated index and a target shape is reduced.
Equipment for manufacturing objects.

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