JP2019209359A - Manufacturing method of welded structure and welded structure - Google Patents

Abstract

To provide a manufacturing method of a welded structure and the welded structure capable of manufacturing the welded structure having improved fatigue strength of a forming part which is formed on base metal according to lamination forming.SOLUTION: A manufacturing method of a welded structure of manufacturing the welded structure W which forms a forming part 53 on the surface 55 of base metal 51 includes a lamination process of forming a laminate part 57 which becomes the forming part 53 by laminating weld beads 61 provided by melting and solidifying filler material M onto the surface 55 of the base metal 51 in layers and a cutting process of cutting the laminate part 57 to work the laminate part into the forming part 53. Therein, in the lamination process, when forming the weld beads 61 of at least the undermost layer, on the outer side of a joint area of the base metal 51 to which the forming part 53 is joined, weld bead 61a for heat input which is caused to continue with the weld beads 61 becoming the forming part 53 and does not become the forming part 53 is formed and, on the cutting process, the weld bead 61a for heat input is cut and removed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a welded structure and a welded structure.

  In recent years, there is an increasing need for modeling using a 3D printer as a production means, and research and development are being promoted toward the practical use of modeling using metal materials. A 3D printer that forms a metal material uses a heat source such as a laser, an electron beam, or an arc to melt a metal powder or a metal wire, and manufactures a welded structure by laminating the molten metal.

  By the way, when a weld bead is welded to a base material made of a bulk material or the like and layered, a heat-affected zone in which the structure and characteristics are different from the base material due to the influence of heat at the time of welding in the vicinity of the base portion of the base material ( HAZ: Heat Affected Zone) occurs. In the heat affected zone, a softened layer with reduced hardness is formed in a portion adjacent to the base material that is not affected by heat during welding, and residual stress increases in the softened layer. For this reason, when a large tensile stress when an external force is applied to the modeling part is added to the position of the softened layer, there is a possibility that a fatigue crack may be generated due to the residual stress and the tensile stress acting on the softened layer.

  In Patent Document 1, it is known that cutting is performed on the outer surface of a seam welded portion of a steel pipe that has been seam welded from the inner and outer surfaces to prevent hydrogen-induced lateral cracking due to welding residual stress. As a technique for suppressing fatigue damage due to the influence of welding residual stress in the vicinity of the toe of the weld bead in a welded structure, Patent Document 2 discloses a weld bead on the surface of the base metal adjacent to the weld bead of the weld. It is known that a striking trace is formed along the edge of the weld bead and compressive residual stress is introduced in the vicinity of the toe of the weld bead. Although these patent documents 1 and 2 are the techniques which reduce the residual stress by welding, neither is the technique regarding additive manufacturing.

JP 2012-051033 A JP2013-1336096A

  The objective of this invention is providing the manufacturing method of a welded structure and the welded structure which can manufacture the welded structure in which the fatigue strength of the modeling part formed on a base material by layered modeling was improved. is there.

The present invention has the following configuration.
(1) A method for manufacturing a welded structure for manufacturing a welded structure in which a shaped part is formed on the surface of a base material,
A laminating step of laminating a welding bead obtained by melting and solidifying a filler material on the surface of the base material in a layered manner to form a laminating portion that becomes the modeling portion;
A cutting step of cutting the laminated portion to process the shaped portion;
Including
In the laminating step, when forming a welding bead of the lowest layer at least, the modeling part is continuously connected to the welding bead serving as the modeling part outside the bonding region of the base material to which the modeling part is bonded. Forming the weld bead for heat input that does not become,
A method for manufacturing a welded structure, wherein the welding bead for heat input is removed by cutting in the cutting step.
(2) With the base material,
A shaped part formed by cutting a laminated part formed by laminating a plurality of welding beads formed on the surface of the base material and melted and solidified the filler material;
With
The base material has a cutting region having a width larger than the bead width of the welding bead, which is obtained by cutting and removing a part of the laminated portion outside the joining region of the base material to which the modeling portion is joined. Having welded structure.

  According to the present invention, it is possible to manufacture a welded structure in which the fatigue strength of a modeled portion formed on a base material by additive manufacturing is improved.

It is sectional drawing of the welded structure manufactured with the manufacturing method of this invention. It is a typical schematic block diagram of the manufacturing system which manufactures a welded structure. It is sectional drawing of the welded structure after the lamination process in the manufacturing method of the welded structure of this invention. It is a figure which shows the welded structure which concerns on a reference example, Comprising: (a) is sectional drawing of a welded structure, (b) is a schematic diagram which shows the residual stress in the base material of a welded structure, (c) is a modeling part. It is a schematic diagram which shows the stress which generate | occur | produces in a base material when external force acts. It is a figure which shows the welded structure of this invention, Comprising: (a) is sectional drawing of a welded structure, (b) is a schematic diagram which shows the residual stress in the preform | base_material of a welded structure, (c) is external force to a modeling part. It is a schematic diagram which shows the stress which generate | occur | produces in a base material when acted. It is a figure explaining the modification 1, Comprising: (a) is sectional drawing of the welded structure after a lamination process, (b) is sectional drawing of the welded structure after a cutting process. It is a figure explaining the modification 2, Comprising: (a) is sectional drawing of the welded structure after a lamination process, (b) is sectional drawing of the welded structure after a cutting process.

  Hereinafter, a manufacturing method of a welded structure and a welded structure according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the welded structure W manufactured by the manufacturing method according to this embodiment includes a base material 51 and a modeling portion 53. The base material 51 is a plate material made of steel. The modeling portion 53 is formed in a plate shape and is erected on the surface 55 of the base material 51. The modeling part 53 is configured by laminating a plurality of welding beads 61. The modeling part 53 is formed by cutting a later-described laminated part 57 (see FIG. 3) in which the weld beads 61 are laminated.

  The base material 51 includes a joining area JA to which the modeling portion 53 is joined, and a cutting area SA in which a part of the laminated portion 57 formed on the surface 55 of the base material 51 is cut and removed outside the joining area JA. And having. This cutting area SA has a width W3 that is at least larger than the bead width Wb of the weld bead 61.

  Further, a weld bead 61 is welded to the surface 55 side of the base material 51, that is, a heat-affected zone (having a different structure and characteristics from the base material 51 due to the influence of heat when the laminated portion 57 is formed ( HAZ: Heat Affected Zone) HA is formed. The heat affected zone HA is formed in a wider range than the stacked portion 57. In particular, in the present embodiment, in the plate width direction of the modeling portion 53, the heat-affected zone HA is a cutting region where the width W1 of the joining region JA where the modeling portion 53 is formed and the laminated portion 57 are formed and removed by cutting. It is formed in a range of the width W2 wider than the total of the SA widths W3.

Next, a manufacturing system for manufacturing the welded structure W will be described with reference to FIG.
As illustrated in FIG. 2, the manufacturing system 100 having this configuration includes a layered modeling apparatus 11, a cutting apparatus 12, and a controller 15 that performs overall control of the layered modeling apparatus 11 and the cutting apparatus 12.

  The additive manufacturing apparatus 11 includes a welding robot 19 having a torch 17 on a tip shaft, and a filler material supply unit 21 that supplies a filler material (welding wire) M to the torch 17. The torch 17 holds the filler material M in a state protruding from the tip.

  The welding robot 19 is an articulated robot, and the filler material M is supported on the torch 17 provided on the tip shaft so as to be continuously supplied. The position and orientation of the torch 17 can be arbitrarily set three-dimensionally within the range of the degree of freedom of the robot arm.

  The torch 17 has a shield nozzle (not shown), and shield gas is supplied from the shield nozzle. The arc welding method used in this configuration may be either a consumable electrode type such as covered arc welding or carbon dioxide arc welding, or a non-consumable electrode type such as TIG welding or plasma arc welding. It is selected appropriately according to.

  For example, in the case of the consumable electrode type, a contact tip is disposed inside the shield nozzle, and a filler material M to which a molten current is fed is held by the contact tip. The torch 17 generates an arc from the tip of the filler material M in a shield gas atmosphere while holding the filler material M. The melt material M is fed from the melt material supply unit 21 to the torch 17 by a feed mechanism (not shown) attached to a robot arm or the like. Then, when the melt material M that is continuously fed is melted and solidified while moving the torch 17, a linear weld bead 61 that is a melt-solidified body of the melt material M is formed on the base material 51 described later. Is done.

  The heat source for melting the filler material M is not limited to the arc described above. For example, a heat source using other methods such as a heating method using both an arc and a laser, a heating method using plasma, and a heating method using an electron beam or a laser may be adopted. When heating with an electron beam or a laser, the amount of heating can be controlled more finely, the state of the weld bead can be maintained more appropriately, and the quality of the welded structure W can be further improved.

  As the melt material M, any commercially available welding wire can be used. For example, it is defined by MAG welding and MIG welding solid wire (JIS Z 3312) for mild steel, high strength steel and low temperature steel, arc welding flux cored wire (JIS Z 3313) for mild steel, high strength steel and low temperature steel. Can be used.

  The cutting device 12 includes a cutting robot 41. The cutting robot 41 is an articulated robot similar to the welding robot 19, and includes a metal processing tool 45 such as an end mill or a grinding wheel at the tip of the tip arm 43. Thereby, the cutting robot 41 can be moved three-dimensionally by the controller 15 so that the processing posture can take an arbitrary posture.

  The cutting robot 41 uses the metal processing tool 45 to cut the laminated portion 57 in which the welding bead 61 is laminated on the base material 51 by the welding robot 19 of the layered shaping apparatus 11 to process the shaped portion 53.

  The controller 15 includes a CAD / CAM unit 31, a trajectory calculation unit 33, a storage unit 35, and a control unit 37 to which these are connected.

  The CAD / CAM unit 31 creates shape data of the welded structure W to be manufactured, and then generates layer shape data representing the shape of each layer by dividing the data into a plurality of layers. The trajectory calculation unit 33 obtains the movement trajectory of the torch 17 based on the generated layer shape data. Further, the trajectory calculation unit 33 obtains the movement trajectory of the metal working tool 45 based on the shape data. The storage unit 35 stores data such as the shape data of the welded structure W, the generated layer shape data, the movement locus of the torch 17 and the movement locus of the metal working tool 45.

  The control unit 37 drives the welding robot 19 by executing a drive program based on the layer shape data stored in the storage unit 35 and the movement trajectory of the torch 17. That is, the welding robot 19 moves the torch 17 while melting the filler metal M with an arc based on the movement trajectory of the torch 17 generated by the trajectory calculation unit 33 according to a command from the controller 15. In addition, the control unit 37 drives the cutting robot 41 by executing a drive program based on the shape data stored in the storage unit 35 and the movement locus of the metal working tool 45. Accordingly, the welding structure W is cut by the metal working tool 45 provided on the tip arm 43 of the cutting robot 41.

  Next, the manufacturing method of the welded structure of this embodiment is demonstrated with reference to FIG.1 and FIG.3.

(Lamination process)
First, the base material 51 is set in the manufacturing system 100. Next, the melt material M is melted while moving the torch 17 of the additive manufacturing apparatus 11 by driving the welding robot 19 along the movement trajectory of the torch 17 generated from the set layer shape data, and FIG. As shown, the melted filler material M is supplied to the surface 55 of the base material 51. As a result, a plurality of linear weld beads 61 are arranged in parallel on the surface 55 of the base material 51 to form each layer, and each layer is further laminated to form a laminated portion 57.

  Here, when forming the lowest-layer weld bead 61, it is for heat input that does not become the modeling part 53 continuously with the welding bead 61 to be the modeling part 53 outside the joining area JA to which the modeling part 53 is joined. A weld bead 61a is formed. The heat input welding beads 61a may be formed at least one on the outer side of the bonding area JA in the plate width direction of the modeling portion 53, but preferably the width W1 of the bonding area JA of the base material 51. Multiple pieces are formed so as to form the above range.

  For example, when the width of the lowermost layered portion 57 is W0, the bead width of the weld bead 61 is Wb, and the number of weld beads 61a for heat input is n in the plate width direction of the modeling portion 53, the following formula ( The welding bead 61a for heat input is formed so as to satisfy 1).

  W0−W1 ≧ n × Wb (1)

(Cutting process)
The cutting robot 41 is driven to cut the laminated portion 57 with the metal working tool 45, thereby forming the welded structure W in which the plate-shaped modeling portion 53 is erected on the surface 55 of the base material 51. Specifically, the laminated portion 57 located outside the both side surfaces of the modeling portion 53 is cut, and the welding bead 61a for heat input of the laminated portion 57 formed on the surface 55 of the base material 51 is cut and removed. .

  And in the welding structure W manufactured by said lamination process and cutting process, the plate-shaped modeling part 53 is formed in the surface 55 of the base material 51, and the both sides of the board | substrate width direction of the modeling part 53 in the base material 51 are formed. Then, a cutting area SA is formed by cutting and removing a part of the laminated portion 57. Therefore, the cutting area SA has a width that is at least larger than the bead width Wb of the weld bead 61. Specifically, in the plate width direction of the modeling portion 53, the cutting area SA is provided outside the joining area JA in a range equal to or greater than the width W1 of the joining area JA of the base material 51. Similarly, in the plate width direction of the modeling portion 53, the heat affected zone HA is provided outside the bonding area JA and in a range equal to or larger than the width W1 of the bonding area JA of the base material 51.

  Here, in the reference example shown in FIG. 4 (a), the laminated portion 57 is formed without forming the heat input bead 61a, and the shaped portion 53 is formed by cutting the laminated portion 57 by a cutting process. Yes. In this reference example, since the laminated portion 57 is formed without forming the heat-input welding bead 61 a, the heat-affected zone HA formed in the base material 51 is the lowermost welding bead of the laminated portion 57. It is formed over the vicinity of the modeling part 53 including the place where 61 is formed.

  Therefore, in this reference example, the position of the softened layer N formed in the vicinity of the boundary between the heat-affected portion HA and the base material not affected by heat is in the vicinity of the modeling portion 53. For this reason, as shown in FIG. 4B, the residual stress σ1 of the base material 51 is maximized in the vicinity of the modeling portion 53 where the softened layer N is formed. Further, as shown in FIG. 4C, when an external force F along the plate width direction acts on the modeling part 53, the tensile stress σ <b> 2 applied to the base material 51 by the external force F approaches the modeling part 53. growing.

  Therefore, in this reference example, when an external force F acts on the modeling portion 53, a large tensile stress σ2 is applied to a location near the softened layer N in the base material 51 having a large residual stress σ1. That is, the total stress (σ1 + σ2) obtained by adding the large tensile stress σ2 to the residual stress σ1 is concentrated at the position of the softened layer N in the base material 51, and there is a possibility that a fatigue crack is generated.

  On the other hand, in the welded structure W manufactured by the manufacturing method according to this embodiment, as shown in FIG. 5A, the weld bead that becomes the modeling portion 53 on both sides in the plate width direction of the modeling portion 53. By forming the welding bead 61a for heat input that does not become the modeling part 53 continuously with 61, the range of the heat affected part HA is expanded, and the softened layer N of the heat affected part HA is moved away from the modeled part 53. be able to. That is, as shown in FIG. 5B, the position of the softened layer N having a large residual stress σ <b> 1 can be arranged at a position as far as possible from the modeling portion 53. On the other hand, as shown in FIG. 5C, the tensile stress σ <b> 2 applied to the base material 51 by the external force F along the plate width direction acting on the modeling portion 53 approaches the modeling portion 53 as described above. It grows according to. Therefore, in the welded structure W in which the softened layer N is positioned far from the modeling portion 53, the tensile stress σ2 applied at the position of the softened layer N is small.

  Thus, in the present embodiment, the position of the softened layer N having a large residual stress σ1 is a position sufficiently separated from the modeling portion 53 where the tensile stress σ2 applied by the external force F becomes small. That is, the total stress (σ1 + σ2) obtained by adding a relatively small tensile stress σ2 to the residual stress σ1 is added to the position of the softened layer N in the base material 51, thereby suppressing stress concentration and suppressing fatigue cracks. It becomes possible to do.

  As described above, according to the present embodiment, the welding bead 61a for heat input that does not become the modeling part 53 by being continuous with the welding bead 61 that becomes the modeling part 53 on both sides in the plate width direction of the modeling part 53. Form. Thereby, the range of the heat affected zone HA can be expanded, and the softened layer N of the heat affected zone HA can be positioned away from the modeling portion 53. Therefore, the tensile stress σ2 generated at the position of the softened layer N where the large residual stress σ1 exists can be reduced, and the stress concentration at the position of the softened layer N can be suppressed to suppress the fatigue crack.

  Further, the welding bead 61a for heat input that is formed in order to separate the position of the softening layer N from the modeling portion 53 is removed by cutting together with the laminated portion 57 when it is processed into the modeling portion 53. Even if the welding bead 61a for heat input is formed, the labor of the cutting process can be minimized.

  Moreover, in the present embodiment, in the laminating step, the welding beads 61a for heat input are formed on both sides of the modeling portion 53 in the plate width direction over at least the width W1 or more of the joining area JA. Thereby, the position of the softening layer N can be sufficiently separated from the modeling portion 53, and the durability at the position of the softening layer N can be reliably ensured.

  In particular, when the width of the bonding area JA is W1, the width of the laminated portion is W0, the bead width of the weld bead 61 is Wb, and the number of weld beads 61a for heat input is n in the plate width direction of the modeling portion 53. , The welding bead 61a for heat input is formed so as to satisfy W0−W1 ≧ n × Wb. Thereby, the welding bead 61a for sufficient heat input can be formed without waste, and durability at the position of the softened layer N can be enhanced.

  As described above, the present invention is not limited to the above-described embodiments, and those skilled in the art can change and apply the configurations of the embodiments based on the combination of each other, the description of the specification, and well-known techniques. This is also the scope of the present invention, and is included in the scope for which protection is sought.

  For example, in the above-described embodiment, the welding bead 61a for heat input is formed only in the lowermost layer in contact with the surface 55 of the base material 51. However, the present invention is not limited to the heat affected zone HA formed in the base material 51. The range should just be formed to the position away from the modeling part 53 as much as necessary. For this reason, the welding bead 61a for heat input may be formed with the welding bead 61 used as a modeling part over a predetermined number of layers from the lowest layer. Specifically, as in Modification 1 shown in FIG. 6, the welding bead 61a for heat input is inclined so that the width in the plate width direction gradually decreases from the lowermost layer to a predetermined number of layers. It may be laminated. Alternatively, as in Modification 2 shown in FIG. 7, the welding beads 61a for heat input may be stacked from the lowest layer to a predetermined number of layers without changing the width in the plate width direction.

  Moreover, in this embodiment, although the base material 51 is made into the plate material and the modeling part 53 is formed in plate shape, it is not restricted to this, For example, the base material 51 may be a columnar member.

As described above, the following items are disclosed in this specification.
(1) A method for manufacturing a welded structure for manufacturing a welded structure in which a shaped part is formed on the surface of a base material,
A laminating step of laminating a welding bead obtained by melting and solidifying a filler material on the surface of the base material in a layered manner to form a laminating portion that becomes the modeling portion;
A cutting step of cutting the laminated portion to process the shaped portion;
Including
In the laminating step, when forming a welding bead of the lowest layer at least, the modeling part is continuously connected to the welding bead serving as the modeling part outside the bonding region of the base material to which the modeling part is bonded. Forming the weld bead for heat input that does not become,
A method for manufacturing a welded structure, wherein the welding bead for heat input is removed by cutting in the cutting step.
According to this method for manufacturing a welded structure, the range of the heat affected zone can be expanded, and the softened layer at the boundary between the heat affected zone and the portion not affected by the heat can be positioned away from the shaped portion. Therefore, even when an external force along the plate width direction acts on the modeling part, the tensile stress generated at the position of the softened layer where a large residual stress exists can be reduced, and the stress concentration at the modeling part can be suppressed and modeling can be performed. The fatigue strength of the part can be improved.
In addition, the welding bead for heat input formed in order to separate the position of the softened layer from the modeling part is removed by cutting when the laminated part is cut and processed into the modeling part. Even if the bead is formed, the labor of the cutting process can be minimized.

(2) The modeling portion is formed in a plate shape,
In the laminating step, the welding bead for heat input is formed over a range equal to or larger than the width of the joining region of the base material on the outside of the joining region of the base material in the plate width direction of the modeling part (1). The manufacturing method of the welded structure as described in 2.
According to this method for manufacturing a welded structure, the position of the softened layer can be sufficiently separated from the modeling part, and the fatigue strength of the modeling part can be improved.

(3) The modeling part is formed in a plate shape,
In the plate width direction of the modeling part, the width of the bonding region of the base material is W1, the width of the laminated part is W0, the bead width of the welding bead is Wb, and the number of welding beads for heat input is n. sometimes,
W0-W1 ≧ n × Wb
The method for manufacturing a welded structure according to (1) or (2), wherein the welding bead for heat input is formed in the laminating step so as to satisfy the condition.
According to this method for manufacturing a welded structure, a sufficient weld bead for heat input can be formed without waste, and the fatigue strength of the shaped part can be improved.

(4) With the base material,
A shaped part formed by cutting a laminated part formed by laminating a plurality of welding beads formed on the surface of the base material and melted and solidified the filler material;
With
The base material has a cutting region having a width larger than the bead width of the welding bead, which is obtained by cutting and removing a part of the laminated portion outside the joining region of the base material to which the modeling portion is joined. Having welded structure.
According to this welded structure, the range of the heat-affected zone in the base material is expanded, and the softened layer at the boundary between the heat-affected zone and the portion not affected by heat is positioned away from the modeling portion. Therefore, even when an external force along the plate width direction acts on the modeling part, the tensile stress generated at the position of the softened layer where a large residual stress exists can be reduced, and the stress concentration at the modeling part can be suppressed and modeling can be performed. The fatigue strength of the part can be improved.
Moreover, since the cutting region can be formed by cutting together with the laminated portion when it is cut into a modeling portion, the labor for forming the cutting region can be minimized.

(5) The modeling portion is formed in a plate shape,
The welding structure according to (4), wherein the cutting region is provided outside the bonding region of the base material over a range equal to or larger than the width of the bonding region of the base material in the plate width direction of the modeling portion.
According to this welded structure, the position of the softened layer can be sufficiently separated from the modeling part, and the fatigue strength of the modeling part can be improved.

51 Base material 53 Modeling part 55 Surface 57 Laminating part 61, 61a Welding bead M Filling material n Number of welding beads for heat input SA Cutting area W Welded structure W0 Width of laminating part W1 Width of joining area Wb Bead width

Claims (5)

A manufacturing method of a welded structure for manufacturing a welded structure in which a shaped part is formed on the surface of a base material,
A laminating step of laminating a welding bead obtained by melting and solidifying a filler material on the surface of the base material in a layered manner to form a laminating portion that becomes the modeling portion;
A cutting step of cutting the laminated portion to process the shaped portion;
Including
In the laminating step, when forming a welding bead of the lowest layer at least, the modeling part is continuously connected to the welding bead serving as the modeling part outside the bonding region of the base material to which the modeling part is bonded. Forming the weld bead for heat input that does not become,
A method for manufacturing a welded structure, wherein the welding bead for heat input is removed by cutting in the cutting step. The modeling part is formed in a plate shape,
The said lamination process forms the welding bead for said heat input over the range beyond the width | variety of the joining area | region of the said base material in the board width direction of the said modeling part on the outer side of the joining area | region of the said base material. The manufacturing method of the welded structure as described in 2. The modeling part is formed in a plate shape,
In the plate width direction of the modeling part, the width of the bonding region of the base material is W1, the width of the laminated part is W0, the bead width of the welding bead is Wb, and the number of welding beads for heat input is n. sometimes,
W0-W1 ≧ n × Wb
The said lamination process is a manufacturing method of the welded structure of Claim 1 or Claim 2 which forms the said welding bead for heat input so that it may satisfy | fill. With the base material,
A shaped part formed by cutting a laminated part formed by laminating a plurality of welding beads formed on the surface of the base material and melted and solidified the filler material;
With
The base material has a cutting region having a width larger than the bead width of the welding bead, which is obtained by cutting and removing a part of the laminated portion outside the joining region of the base material to which the modeling portion is joined. Having welded structure. The modeling part is formed in a plate shape,
The welded structure according to claim 4, wherein the cutting region is provided outside the bonding region of the base material over a range equal to or larger than the width of the bonding region of the base material in the plate width direction of the modeling portion.

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