Patent Publication Number: US-2022226943-A1

Title: Manufacturing method for additive manufactured article and additive manufactured article

Description:
TECHNICAL FIELD 
     The present invention relates to a method for manufacturing an additively-manufactured object and an additively-manufactured object. 
     BACKGROUND ART 
     In recent years, needs for 3D printers as a means of manufacturing have been increasing, and research and development have been carried out for practical use in the aircraft industry and the like, especially for application to metal materials. A 3D printer using a metal material melts a metal powder or a metal wire by using a heat source such as a laser or an arc, and deposits the molten metal to build a built-up object. 
     As a technique for building such an additively-manufactured object, there is known a technique for manufacturing a three-dimensional shaped object by performing scanning with a torch along a horizontal plane or an inclined surface to advance surfacing in a torch scanning step (see, for example, Patent Literature 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: JP-A-2003-266174 
     SUMMARY OF INVENTION 
     Technical Problem 
     In a case where a weld bead is formed on a substrate or a base portion of a lower weld bead, when the base portion is a vertical surface or an inclined surface, dripping due to the influence of gravity may occur. In addition, when a moving speed of the welding torch is increased in order not to drip the weld bead, humping which interrupts the weld bead may occur. Therefore, there is a demand for a technique for smoothly forming a weld bead to manufacture a built-up object without being influenced by the state of the base portion on which the weld bead is formed and without any problems such as dripping or humping. 
     The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing an additively-manufactured object by which a weld bead is efficiently formed to build an additively-manufactured object without any problems such as dripping or humping, and an additively-manufactured object. 
     Solution to Problem 
     The present invention has the following configurations. 
     (1) A method for manufacturing an additively-manufactured object, in which a plurality of weld beads obtained by melting and solidifying a filler metal are deposited on a base portion to build a built-up object, the method including: 
     a support bead forming step of forming a support bead on the base portion; and 
     a depositing step of depositing a weld bead on the support bead, in which, 
     when the support bead is formed to be inclined from a vertical direction in the support bead forming step, a ratio H/W of a height H to a width W of the support bead is set to 0.35 or more. 
     (2) An additively-manufactured object formed by depositing, on a base portion, a plurality of weld beads obtained by melting and solidifying a filler metal, the additively-manufactured object including: 
     a support bead formed on the base portion; and 
     a weld bead deposited on the support bead, in which 
     the support bead has a ratio H/W of a height H to a width W of an overhang-shaped portion having an overhang of 0.35 or more. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to efficiently form a weld bead to build an additively-manufactured object without any problems such as dripping or humping. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram of a manufacturing system for manufacturing an additively-manufactured object. 
         FIG. 2A  is a schematic side view of the additively-manufactured object being manufactured, which shows a procedure for manufacturing the additively-manufactured object. 
         FIG. 2B  is a schematic side view of the additively-manufactured object being manufactured, which shows the procedure for manufacturing the additively-manufactured object. 
         FIG. 2C  is a schematic side view of the additively-manufactured object being manufactured, which shows the procedure for manufacturing the additively-manufactured object. 
         FIG. 2D  is a schematic side view of the additively-manufactured object being manufactured, which shows the procedure for manufacturing the additively-manufactured object. 
         FIG. 3  is a schematic side view showing a state of a support bead formed on a base portion. 
         FIG. 4A  is a perspective view of the additively-manufactured object being manufactured, which shows an example of the procedure for manufacturing the additively-manufactured object. 
         FIG. 4B  is a perspective view of the additively-manufactured object being manufactured, which shows the example of the procedure for manufacturing the additively-manufactured object. 
         FIG. 4C  is a perspective view of the additively-manufactured object being manufactured, which shows the example of the procedure for manufacturing the additively-manufactured object. 
         FIG. 4D  is a perspective view of the additively-manufactured object being manufactured, which shows the example of the procedure for manufacturing the additively-manufactured object. 
         FIG. 5  is a perspective view of the additively-manufactured object being manufactured, which shows another example of the procedure for manufacturing the additively-manufactured object. 
         FIG. 6A  is a perspective view showing a formation state of a weld bead in Test Example 1. 
         FIG. 6B  is a perspective view showing a formation state of a weld bead in Test Example 5. 
         FIG. 7  is a graph showing a relationship of a welding cross-sectional area with respect to a ratio of a height to a width of the weld bead. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 
       FIG. 1  is a schematic configuration diagram of a manufacturing system for manufacturing an additively-manufactured object according to the present invention. 
     A manufacturing system  100  having this configuration includes a depositing-building device  11  and a controller  16  that controls the depositing-building device  11  in an integrated manner. 
     The depositing-building device  11  includes a welding robot  19  having a torch  17  on a tip shaft, and a filler metal feeding unit  21  for feeding a filler metal (weld wire) M to the torch  17 . 
     The controller  16  includes a CAD/CAM unit  31 , a track calculation unit  33 , a storage unit  35 , and a control unit  37  connected to the above units. 
     The welding robot  19  is an articulated robot, and the torch  17  provided on the tip shaft is supported such that the filler metal M can be continuously fed. The position or posture of the torch  17  can be set three-dimensionally desirably within the range of the degree of freedom of the robot arm. 
     The torch  17  includes a not-shown shield nozzle, and shielding gas is supplied from the shield nozzle. 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 welding or plasma arc welding. The arc welding method is appropriately selected depending on an additively-manufactured object to be manufactured. 
     For example, in the case of the consumable electrode type, a contact tip is disposed inside the shield nozzle, and the filler metal M to which a melting current is to be supplied is held on the contact tip. The torch  17  generates an arc from the tip of the filler metal M in a shielding gas atmosphere while holding the filler metal M. The filler metal M is fed from the filler metal feeding unit  21  to the torch  17  by a not-shown delivery mechanism attached to the robot arm or the likes. Then, when the filler metal M continuously fed is melted and solidified while moving the torch  17 , a linear weld bead B, which is a melt-solidified body of the filler metal M, is formed on a base plate  10 . 
     A heat source for melting the filler metal M is not limited to the aforementioned arc. The heat source using another system such as a heating system using an arc and a laser together, a heating system using plasma, or a heating system using an electron beam or a laser may be used. In the case of heating by an electron beam or a laser, a heating amount can be controlled more finely to keep the weld bead in a more proper state, thereby contributing to further improvement of the quality of the additively-manufactured object. 
     The CAD/CAM unit  31  creates shape data of the additively-manufactured object to be manufactured, and then divides the additively-manufactured object into a plurality of layers to generate layer shape data representing the shape of each layer. The track calculation unit  33  obtains a movement track of the torch  17  based on the generated layer shape data. The storage unit  35  stores data such as the generated layer shape data and the movement track of the torch  17 . 
     The control unit  37  drives the welding robot  19  by executing a drive program based on the layer shape data or the movement track of the torch  17  stored in the storage unit  35 . 
     The control unit  37  drives the welding robot  19  by executing a drive program based on the layer shape data or the movement track of the torch  17  stored in the storage unit  35 . That is, the welding robot  19  moves the torch  17  while melting the filler metal M with an arc based on the movement track of the torch  17  generated by the track calculation unit  33  in response to a command from the controller  16 .  FIG. 1  shows a state where a plurality of weld beads B are deposited on the vertically installed base plate  10  made of a steel plate to build an additively-manufactured object W 1 . 
     The manufacturing system  100  having the above configuration melts the filler metal M while moving the torch  17  by driving the welding robot  19  along the movement track of the torch  17  generated based on the set layer shape data, and supplies the molten filler metal M onto the base plate  10 . Accordingly, for example, the additively-manufactured object W 1  in which a plurality of linear weld beads B are deposited in a horizontal direction on a base portion  13  of the vertically installed base plate  10  is built. 
     When the weld bead B is deposited on a base portion having a vertical surface or an inclined surface inclined from a vertical direction to build the additively-manufactured object W 1  having an overhang-shaped portion, the weld bead B to be deposited may drip due to the influence of gravity. In such a case where the weld bead B to be formed is greatly influenced by gravity, dripping may be prevented by increasing the moving speed of the torch  17 , but there is a possibility that the weld bead B may be interrupted and humping occurs. 
     Therefore, in the present embodiment, the additively-manufactured object W 1  is built while preventing dripping and humping in the weld bead B as follows. Here, a case where the weld bead B is formed in the horizontal track direction on the base portion  13  of the base plate  10 , which is a vertical surface, to build the additively-manufactured object W 1  will be described. 
       FIG. 2A  to  FIG. 2D  are schematic side views of the additively-manufactured object being manufactured, which show a procedure for manufacturing the additively-manufactured object. 
     Support Bead Forming Step 
     As shown in  FIG. 2A , a support bead Bs made of the weld bead B is formed on the base portion  13  of the base plate  10  whose surface is a vertical surface. Specifically, the tip of the torch  1  with the filler metal M protruded therefrom is disposed toward the base portion  13  of the base plate  10 , and the torch  17  is moved in the horizontal direction, which is a track direction, while melting the filler metal M with an arc. Accordingly, the support bead Bs is formed along the horizontal direction on the base portion  13  having a vertical surface. At this time, the support bead Bs to be formed is formed such that a ratio of a height H to a width W is 0.35 or more (H/W≥0.35). 
     Here, a state of the support bead Bs formed on the base portion  13  will be described. 
       FIG. 3  is a schematic side view showing a state of the support bead formed on the base portion. 
     As shown in  FIG. 3 , when the support bead Bs is formed along the horizontal direction with respect to the base portion  13  having a vertical surface, gravity G acts on this support bead Bs. In addition, due to an inclination angle γ of the torch  17  with respect to the vertical direction, a downward component force Fa·cos γ at an arc pressure Fa acts downward in the vertical direction. Then, a surface tension Fst, which is an apparent viscous force of the support bead Bs to be formed, is given by the following equation (1). 
       Fst= G +Fa·cos γ  (1)
 
     In a case where the weld bead B is formed on the base portion  13 , when a current value of the arc increases, the entire arc pressure Fa increases, and accordingly the weld bead B becomes to have a flat shape. Moreover, when the current value of the arc increases, the downward component force Fa·cos γ at the arc pressure Fa increases, and the weld bead tends to drip. In addition, even when the inclination angle γ of the torch  17  with respect to the vertical direction is small, the downward component force Fa·cos y at the arc pressure Fa increases, and the weld bead tends to drip. Further, when an amount of welding to the base portion  13  increases, the influence of the gravity G increases, and the weld bead B tends to drip. 
     In this example, for example, when forming the support bead Bs, the current value of the arc, a voltage value of the arc, the moving speed of the torch  17 , the angle of the torch  17 , and the like are adjusted. Accordingly, the support bead Bs is formed such that a ratio of a height H to a width W is 0.35 or more (H/W≥0.35). Then, the support bead Bs to be formed on the base portion  13  is formed on the base portion  13  without dripping due to the influence of the gravity G. Here, the support bead Bs is formed in the horizontal direction, but the support bead Bs is not necessarily formed horizontally, and may be formed to be inclined from the vertical direction. 
     Support Layer Building Step 
     As shown in  FIG. 2B , a plurality of support beads Bs are sequentially deposited on a side of the support bead Bs that has been formed on the base portion  13 . Accordingly, a support layer  15  in which a plurality of support beads Bs are deposited is built from the base portion  13  toward the side. 
     At this time, each of the support beads Bs is formed such that the ratio of the height H to the width W is also 0.35 or more (H/W≥0.35). Then, the support beads Bs that have been sequentially deposited are formed without dripping due to the influence of the gravity G. 
     Depositing Step 
     As shown in  FIG. 2C , a weld bead Bw wider than the support bead Bs is formed on the support layer  15  formed with the support beads Bs. The wide weld bead Bw is formed along a deposition direction orthogonal to a forming direction of the support beads Bs forming the support layer  15 . At this time, since the weld bead Bw is formed on the support layer  15 , the weld bead Bw is smoothly formed without dripping due to the influence of the gravity G. Accordingly, a wide weld bead Bw can be formed to reduce a formation pass after building the support layer  15 , and the manufacturing efficiency can be improved. As shown in  FIG. 2D , the weld bead Bw may be formed in the same direction as the forming direction of the support beads Bs. 
     Thus, according to the method for manufacturing an additively-manufactured object and the additively-manufactured object of the present embodiment, the ratio of the height H to the width W of the support bead Bs is set to 0.35 or more when forming the support bead Bs on the base portion  13 . Accordingly, the support bead Bs can be formed without dripping with respect to the base portion  13  by preventing the influence of the gravity G. Therefore, the weld bead Bw deposited on this support bead Bs can be prevented from dripping under the influence of the gravity G, and the occurrence of humping that may occur when increasing the moving speed of the torch  17  to prevent dripping can be prevented. Accordingly, the additively-manufactured object W 1  having an overhang-shaped portion protruding from the base portion  13  to the side can be manufactured with high quality while reducing a takt time. 
     In addition, the support bead Bs is deposited from the base portion  13  toward the side to form the support layer  15 , and the wide weld bead Bw is formed on the support layer  15  to form the additively-manufactured object W 1 . That is, the support layer  15  is built with the support bead Bs formed without dripping, and the weld bead Bw wider than the support bead Bs is deposited on the support layer  15 . Therefore, the wide weld bead Bw to be formed on the support layer  15  can be smoothly formed and deposited without dripping due to the influence of the gravity G. Accordingly, the wide weld bead Bw can be formed to reduce the formation pass after building the support layer  15 , and the manufacturing efficiency can be improved. 
     The support layer  15  formed by depositing the support bead Bs from the base portion  13  to the side is formed without dripping. Therefore, for example, by forming a part of a wall such as a ceiling of a cavity portion that serves as a flow path or the like, the additively-manufactured object W 1  having a cavity portion having a stable shape can be obtained. 
     Next, examples of manufacturing the additively-manufactured object by the manufacturing method according to the above embodiment will be described. 
       FIG. 4A  to  FIG. 4D  are perspective views of the additively-manufactured object being manufactured, which show an example of the procedure for manufacturing the additively-manufactured object. 
     As shown in  FIG. 4A , first, the weld bead B is deposited on a plate-shaped base metal  20 , and a bent wall portion (outer frame portion)  40  is formed by depositing the weld bead B while changing a stretching direction. In this example, an example of building the wall portion  40  having a substantially C-shape in a plan view is shown. Alternatively, the weld bead B may have a curved wall portion extending along an arc, a curve, or the like having a curvature such as a substantially U-shape or an O-shape in the plan view. 
     Next, as shown in  FIG. 4B , a part of an inner surface side of the wall portion  40  is used as a base portion  43 , and the support bead Bs is formed on an upper edge portion of the base portion  43  (support bead forming step). At this time, the support bead Bs to be formed is formed such that the ratio of the height H to the width W is 0.35 or more (H/W≥0.35) (see  FIG. 2A ). 
     Then, a plurality of support beads Bs are sequentially deposited on the side of this support bead Bs. At this time, the support bead Bs is formed such that the ratio of the height H to the width W is also 0.35 or more (H/W≥0.35). Accordingly, as shown in  FIG. 4C , a support layer  45  in which a plurality of support beads Bs are deposited is formed from the base portion  43  toward the side (support layer building step). At this time, start edges and end edges of the support beads Bs are connected to inner sides of the wall portion  40  facing each other. 
     Thereafter, as shown in  FIG. 4D , a weld bead Bw wider than the support beads B is formed and deposited on the wall portion  40  formed by the weld bead B and the support layer  45  formed by the support bead Bs along a direction orthogonal to the forming direction of the support beads Bs (depositing step). When forming this wide weld bead Bw, weaving may be performed to displace the torch  17  in a direction intersecting the forming direction of the weld bead Bw. 
     An additively-manufactured object W 2  formed in this way has a cavity portion S in which the support layer  45  is a ceiling wall, and this cavity portion S can be applied to a flow path, for example. 
     When forming the support layer  45 , since the start edges and the end edges of the support beads Bs are connected to inner surfaces of the wall portion  40  facing each other, dripping of the support beads Bs can be further prevented. In addition, since the support beads Bs are deposited on the inner sides of the wall portion  40  to form a support layer, the length of each support bead Bs can be shortened, and the amount of dripping per support bead Bs can be prevented. Here, the support bead Bs is formed in the horizontal direction, but the support bead Bs is not necessarily formed horizontally, and may be formed to be inclined from the vertical direction. Accordingly, the additively-manufactured object W 1  having an overhang-shaped portion protruding to the side can be manufactured with high quality while reducing a takt time. 
     Next, another example of manufacturing the additively-manufactured object will be described. 
       FIG. 5  is a perspective view of the additively-manufactured object being manufactured, which shows another example of the procedure for manufacturing the additively-manufactured object. 
     As shown in  FIG. 5 , first, the weld bead B is deposited on the plate-shaped base metal  20 , and a plurality of independent wall portions (outer frame portions)  40  are formed. These wall portions  40  are not limited to a case of being vertically installed, and may be inclined to be close to each other toward the upper side, which is the deposition direction of the weld bead B. 
     Next, a part of an inner surface side of one wall portion  40  is used as the base portion  43 , and the support bead Bs is formed on the upper edge portion of the base portion  43  (support bead forming step). At this time, the support bead Bs to be formed is formed such that the ratio of the height H to the width W is 0.35 or more (H/W≥0.35) (see  FIG. 2A ). 
     Then, a plurality of support beads Bs are sequentially deposited on the side of this support bead Bs. At this time, each of the support beads Bs is formed such that the ratio of the height H to the width W is also 0.35 or more (H/W≥0.35). Accordingly, the support layer  45  in which a plurality of support beads Bs are deposited is formed from the base portion  43  toward the side (support layer building step). Then, the support bead Bs is deposited such that the support layer  45  is connected to the upper edge portion on the inner surface side of the other wall portion  40 . 
     At this time, since the start edges and the end edges of the support beads Bs are not limited, each support bead Bs can be formed long. Accordingly, when the support bead Bs is deposited to form the support layer  45 , the number of passes of the support bead Bs can be reduced for efficient building. 
     When building the support layer  45 , a part of the inner surface sides of the wall portions  40  facing each other may be used as base portions  43 , and the support layer  45  may be deposited on and connected at an intermediate position of these base portions  43 . 
     Thereafter, a weld bead Bw wider than the support beads B is formed and deposited on the wall portion  40  formed by the weld bead B and the support layer  45  formed by the support bead Bs along a direction orthogonal to the forming direction of the support beads Bs or along the forming direction (depositing step). In this case, when forming the wide weld bead Bw, weaving may also be performed to displace the torch  17  in a direction intersecting the forming direction of the weld bead Bw. 
     The additively-manufactured object W 2  formed in this way has the cavity portion S in which the support layer  45  is a ceiling wall and both edges are open, and this cavity portion S can be applied to a flow path, for example. 
     EXAMPLES 
     Weld beads B having different heights and widths (height/width) were deposited on the base portion  13  of the base plate  10  having a vertical surface while changing welding conditions (voltage, heat input), and the shape was evaluated. The weld bead B was deposited 5 times in Test Examples 1 to 5. 
     Welding Conditions and Evaluation Results 
     Table 1 shows the welding conditions, the shape of the weld bead, and the evaluation results. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 Welding cross- 
                   
               
               
                   
                 Voltage 
                 Heat input 
                 Bead width 
                 Bead height 
                   
                 sectional area 
                 Shape 
               
               
                   
                 (V) 
                 (J/mm) 
                 (mm) 
                 (mm) 
                 Height/width 
                 (mm 2 ) 
                 evaluation 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Test Example 1 
                 11.8 
                 474 
                 5.76 
                 3.52 
                 0.61 
                 14.41 
                 ∘ 
               
               
                 Test Example 2 
                 13.7 
                 390 
                 6.65 
                 2.91 
                 0.44 
                 11.64 
                 ∘ 
               
               
                 Test Example 3 
                 13.7 
                 260 
                 5.30 
                 2.33 
                 0.44 
                 7.76 
                 ∘ 
               
               
                 Test Example 4 
                 16.1 
                 547 
                 9.94 
                 2.91 
                 0.29 
                 19.21 
                 x 
               
               
                 Test Example 5 
                 16.1 
                 274 
                 7.50 
                 2.07 
                 0.28 
                 9.61 
                 x 
               
               
                   
               
            
           
         
       
     
     All of Test Example 1 (height/width=0.61) and Test Examples 2 and 3 (height/width=0.44) were evaluated to be passed (evaluation ○ in Table 1).  FIG. 6A  is a diagram showing a formation state of the weld bead B in Test Example 1. As shown in  FIG. 6A , the weld bead B was formed without dripping with respect to the base portion  13 , and was uniformly deposited in the horizontal direction. 
     In contrast, both Test Example 4 (height/width=0.29) and Test Example 5 (height/width=0.28) were evaluated to be failed (evaluation x in Table 1).  FIG. 6B  is a diagram showing a formation state of the weld bead B in Test Example 5. As shown in  FIG. 6B , the weld bead B had dripping from the base portion  13 , and had a non-uniform formation state in the horizontal direction. 
       FIG. 7  shows a relationship of a welding cross-sectional area with respect to the ratio of the height to the width of the formed weld bead B. As see from  FIG. 7 , when the ratio of the height to the width (height/width) is 0.35 or more, regardless of the welding cross-sectional area, the weld bead B can be formed uniformly in the horizontal direction without any problems such as dripping, and particularly, the ratio of the height to the width (height/width) is preferably 0.44 or more. That is, when the ratio of the height to the width (height/width) of the weld bead B is 0.35 or more, the weld bead B can be suitably used as the support bead Bs when forming an additively-manufactured object from the base portion  13  to the side. 
     The present invention is not limited to the above embodiments, and combinations of the respective configurations of the embodiments, or changes and applications made by those skilled in the art based on the description of the specification and the well-known technology are also intended by the present invention and are included within the scope to be protected. 
     As described above, the present description discloses the following matters. 
     (1) A method for manufacturing an additively-manufactured object, in which a plurality of weld beads obtained by melting and solidifying a filler metal are deposited on a base portion to build a built-up object, the method including: 
     a support bead forming step of forming a support bead on the base portion; and 
     a depositing step of depositing a weld bead on the support bead, in which, 
     when the support bead is formed to be inclined from a vertical direction in the support bead forming step, a ratio H/W of a height H to a width W of the support bead is set to 0.35 or more. 
     According to the method for manufacturing an additively-manufactured object having the configuration described in the above (1), the support bead is formed on the base portion, and the weld bead is deposited on this support bead to build a built-up object. When forming the support bead on the base portion, the ratio of the height to the width of the support bead is set to 0.35 or more. Accordingly, the support bead can be formed without dripping with respect to the base portion while preventing the influence of the gravity. Therefore, the weld bead deposited on this support bead can be prevented from dripping under the influence of the gravity, and the occurrence of humping that may occur when increasing the moving speed of the torch to prevent dripping can be prevented. Accordingly, an additively-manufactured object having an overhang-shaped portion protruding from the base portion to the side can be manufactured with high quality while reducing a takt time. 
     (2) The method for manufacturing an additively-manufactured object according to (1), further including: 
     a support layer building step of building a support layer by depositing the support bead to be connected in one direction, in which 
     in the depositing step, a weld bead wider than the support bead is formed on the support layer. 
     According to the method for manufacturing an additively-manufactured object having the configuration described in the above (2), the support bead is deposited to be connected in one direction to form the support layer, and a wide weld bead is formed on the upper portion of the support layer to build an additively-manufactured object. That is, the support layer is built by the support bead formed without dripping, and the weld bead wider than the support bead is deposited on the support layer. Therefore, the wide weld bead to be formed on the support layer can be smoothly formed and deposited without dripping due to the influence of the gravity. Accordingly, the wide weld bead can be formed to reduce the formation pass after building the support layer, and the manufacturing efficiency can be improved. 
     (3) The method for manufacturing an additively-manufactured object according to (2), in which the support layer built in the support layer building step is used as a wall portion forming a cavity portion. 
     According to the method for manufacturing an additively-manufactured object having the configuration described in the above (3), the support layer formed by depositing the support bead to be connected in one direction is formed without dripping. Therefore, for example, by forming a part of a wall such as a ceiling of a cavity portion that serves as a flow path or the like, an additively-manufactured object having a cavity portion having a stable shape can be obtained. 
     (4) The method for manufacturing an additively-manufactured object according to (2) or (3), further including: 
     a step of forming an outer frame portion that is bent or curved by depositing a weld bead while changing a stretching direction, in which 
     a start edge and an end edge of the support bead are set with respect to the outer frame portion, and the support bead is deposited on an inner side of the outer frame portion to form the support layer. 
     According to the method for manufacturing an additively-manufactured object having the configuration described in the above (4), the start edge and the end edge of the support bead are connected to the outer frame portion, so that dripping of the support bead can be further prevented. In addition, since the support beads are deposited on the inner sides of the outer frame portion to form a support layer, the length of each support bead can be shortened, and the amount of dripping per support bead can be prevented. 
     (5) The method for manufacturing an additively-manufactured object according to (2) or (3), further including: 
     a step of depositing a weld bead to form a plurality of independent outer frame portions, in which 
     the support layer is formed to connect the plurality of outer frame portions. 
     According to the method for manufacturing an additively-manufactured object having the configuration described in the above (5), the start edges and the end edges of the support beads are not limited, so that each support bead can be formed long. Accordingly, when the support bead is deposited to form the support layer, the number of passes of the support bead can be reduced for efficient building. 
     (6) An additively-manufactured object formed by depositing, on a base portion, a plurality of weld beads obtained by melting and solidifying a filler metal, the additively-manufactured object including: 
     a support bead formed on the base portion; and 
     a weld bead deposited on the support bead, in which 
     the support bead has a ratio H/W of a height H to a width W of an overhang-shaped portion having an overhang of 0.35 or more. 
     According to the additively-manufactured object having the configuration described in the above (6), the support bead is formed on the base portion, and the weld bead is deposited on the support bead. The support bead formed to protrude from the base portion to the side has a ratio of the height to the width of 0.35 or more. Accordingly, when building an additively-manufactured object, the support bead can be formed without dripping with respect to the base portion while preventing the influence of the gravity. In addition, the weld bead deposited on the support bead can be prevented from dripping under the influence of the gravity, and the occurrence of humping that may occur when increasing the moving speed of the torch to prevent dripping can be prevented. Accordingly, a high-quality additively-manufactured object having an overhang shape while preventing the takt time can be built. 
     (7) The additively-manufactured object according to (4), further including: 
     a support layer in which the support bead is deposited to be connected in one direction, in which 
     a weld bead wider than the support bead is formed on the support layer. 
     According to the additively-manufactured object having the configuration described in the above (7), the wide weld bead is formed on the upper portion of the support layer in which the support bead is deposited to be connected in one direction. That is, the support layer is built by the support bead formed without dripping, and the weld bead wider than the support bead is deposited on the support layer. Therefore, the wide weld bead can be smoothly formed and deposited on the support layer without dripping due to the influence of the gravity. Accordingly, the wide weld bead can be formed to reduce the formation pass after building the support layer, and the manufacturing efficiency can be improved. 
     (8) The additively-manufactured object according to (5), in which the support layer is used as a wall portion forming a cavity portion. 
     According to the additively-manufactured object having the configuration described in the above (8), the support layer in which the support bead is deposited to be connected in one direction is formed without dripping. Therefore, for example, by forming a part of a wall such as a ceiling of a cavity portion that serves as a flow path or the like, an additively-manufactured object having a cavity portion having a stable shape can be obtained. 
     (9) The additively-manufactured object according to (7) or (8), further including: 
     an outer frame portion that is curved and formed by depositing a weld bead while changing a stretching direction, in which 
     the support layer is formed on an inner side of the outer frame portion, the support layer being formed by depositing the support bead both edges of which are connected to an inner surface of the outer frame portion. 
     According to the additively-manufactured object having the configuration described in the above (9), both edges of the support bead are connected to the outer frame portion, so that an additively-manufactured object in which the dripping of the support bead is further prevented can be obtained. In addition, because of a structure in which the support bead is connected to the inner side of the outer frame portion to form the support layer, during the manufacturing, the length of each support bead can be shortened, and the amount of dripping per support bead can be prevented. 
     (10) The additively-manufactured object according to (7) or (8), further including: 
     a plurality of independent outer frame portions formed by depositing a weld bead, in which 
     the support layer is formed to connect the plurality of outer frame portions. 
     According to the additively-manufactured object having the configuration described in the above (10), the start edges and the end edges of the support beads are not limited, so that an additively-manufactured object with a long length of each support bead can be obtained. Accordingly, when the support bead is deposited to form the support layer, the number of passes of the support bead can be reduced for efficient building. 
     The present application is based on a Japanese patent application (Japanese Patent Application No. 2019-91596) filed on May 14, 2019, contents of which are incorporated herein by reference. 
     REFERENCE SIGNS LIST 
       13 ,  43  base portion 
       15 ,  45  support layer 
       40  wall portion (outer frame portion) 
     B, Bw weld bead 
     Bs support bead 
     H height of support bead 
     M filler metal 
     S cavity portion 
     W width of support bead 
     W 1 , W 2  additively-manufactured object