Welding torch and additive manufacturing method

Abstract

This invention provides a welding torch that enables efficient manufacturing of fabricated objects even when performing additive manufacturing with welding materials containing materials or elements that are difficult to process into welding wire. [Solution] The welding torch 10 generates an arc 5 between the welding wire 3A and the workpiece W, melting and solidifying the welding material including the welding wire 3A. The welding torch 10 includes a contact tip 13 that supplies power to the welding wire 3A and guides the welding wire 3A toward the welding area through a wire protrusion port 15 provided at the tip of the torch, a powder flow path 17 that discharges powder 3B as a welding material toward the welding area through a powder discharge port 18 provided at the tip of the torch, and a shielding gas flow path 20 that supplies shielding gas around the arc 5 through a shielding gas nozzle 21 provided at the tip of the torch, with the wire protrusion port 15 and the powder discharge port 18 being formed inside the shielding gas nozzle 21 at the tip of the torch.

Description

Technical Field

[0001] This invention relates to a welding torch suitably used in additive manufacturing and an additive manufacturing method using the same.

Background Art

[0002] As one of the stacking methods of metal additive manufacturing (AM), which is a next-generation production technology, there is a Directed Energy Deposition (DED) method. The DED method is a manufacturing technology that supplies metal powder or welding wire to a molten pool formed by irradiating energy with a laser, an electron beam, or an arc to obtain a desired shape (see, for example, Patent Document 1 below). The DED method has advantages such as a high forming speed, easy switching of the forming material, and few restrictions on the forming size compared to other manufacturing methods.

[0003] In a general DED method, either welding wire or powder is used as the feed material (forming material). When the material or element is difficult to process into a welding wire as the forming material and it is difficult to process the welding wire composed of the composition of the forming material, powder is used as the feed material. However, when powder is used, there is a problem that the welding speed is slower and the productivity is inferior compared to MIG welding using a welding wire as a consumable metal electrode.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Against the backdrop of the above circumstances, the present invention aims to provide a welding torch and an additive manufacturing method that enable efficient production of fabricated objects even when performing additive manufacturing with welding materials containing materials or elements that are difficult to process into welding wire. [Means for solving the problem]

[0006] Thus, the welding torch in the first aspect of this invention is defined as follows: A welding torch that generates an arc between a welding wire and a workpiece to melt and solidify the welding material including the welding wire, A contact tip that supplies power to the welding wire and guides the welding wire toward the welding area through a wire protrusion port provided at the tip of the torch, A powder channel is provided at the tip of the torch to discharge powder, which is used as a welding material, toward the arc. A shielding gas flow path that supplies shielding gas around the arc through a shielding gas nozzle provided at the tip of the torch, Equipped with, At the tip of the torch, the wire protrusion port and the powder discharge port are formed inside the shield gas nozzle.

[0007] According to the first phase of welding torch defined in this way, a weld bead can be formed using both welding material supplied to the welding area in the form of welding wire and welding material supplied to the welding area in powder form. Therefore, even when performing additive manufacturing with welding materials containing materials or elements that are difficult to process into welding wire, the materials or elements that are difficult to process into welding wire can be made into powder, while the materials or elements that can be processed into welding wire can be used as welding wire, and this can be used as a consumable metal electrode. This allows for more efficient manufacturing of the fabricated object compared to when the entire amount of welding material is in powder form. Here, since the powder discharge port is formed inside the shielding gas outlet along with the wire protrusion port, the powder used as welding material can be supplied to the welding area without being obstructed by the shielding gas.

[0008] The additive manufacturing method for the second aspect of this invention is defined as follows: Using an additive manufacturing apparatus including a welding torch as described in the first section, a layer of welding beads is formed on the target surface of the workpiece, and the welding bead layers are laminated to obtain a molded object of a predetermined shape. According to the additive manufacturing method for the second surface as defined in this way, the same effect as that for the first surface is achieved.

[0009] The additive manufacturing method of the third aspect of this invention is defined as follows: In the second phase, the additive manufacturing apparatus includes means for changing the amount of powder supplied to the welding area, The amount of powder supplied to the welding area is changed according to which part of the molded object the weld bead directly below the welding torch corresponds to, thereby obtaining a molded object of a predetermined shape. According to this third aspect, the composition of a part of the molded object can be changed relative to the composition of other parts of the molded object. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the configuration of an additive manufacturing apparatus including a welding torch according to one embodiment of the present invention. [Figure 2] Figure 1 shows a schematic diagram of the welding torch. [Figure 3] This is a cross-sectional view of the tip of the welding torch, taken from the direction of the workpiece, as shown by line III-III in Figure 2. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram showing the configuration of an additive manufacturing apparatus including a welding torch according to one embodiment of the present invention. In the figure, reference numeral 1 denotes an additive manufacturing apparatus that forms a layer of weld bead (weld metal) on the target surface of a workpiece W and stacks these weld bead layers to obtain a molded object of a predetermined shape. The additive manufacturing apparatus 1 comprises a welding torch 10, a wire supply device 30, a welding power supply 35, a shielding gas supply device 40, a powder supply device 44, a carrier gas supply device 47, a drive device 51, and a control unit 55.

[0012] The wire supply device 30 supplies welding wire 3A, which is wound in a coil, to the welding torch 10. The welding wire 3A is a conductor such as metal that can generate an arc with the workpiece W, and is preferably iron, stainless steel, maraging steel, nickel alloy, titanium alloy, copper alloy, or aluminum alloy. The diameter of the welding wire 3A is preferably 1.2 mm or 1.6 mm, but is not limited to these.

[0013] The welding power supply 35 supplies the power necessary to generate an arc between the tip of the welding wire 3A and the workpiece W. One output terminal of the welding power supply 35 is connected via cable 36 to a contact tip 13 (see Figure 2) inside the welding torch 10, and power can be supplied to the welding wire 3A that passes through the welding torch 10 via the contact tip 13. The other output terminal of the welding power supply 35 is connected to the workpiece W via a cable (not shown).

[0014] The shielding gas supply device 40 shown in Figure 1 is connected to the welding torch 10 by a shielding gas supply pipe 41 and supplies shielding gas at a predetermined pressure to the welding torch 10. In this embodiment, for example, an inert gas such as argon can be used as the shielding gas.

[0015] The powder supply device 44 is connected to the welding torch 10 by a powder supply pipe 45, and supplies powder 3B (see FIG. 2) as a welding material to the welding torch 10. The carrier gas supply device 47 is a device that supplies a high-speed carrier gas to the powder supply device 44. The powder supply device 44 includes a powder storage container and a metering device, which are not shown in the figure. Based on a command from the control unit 55, a predetermined supply amount of powder 3B that has been metered is supplied into the powder flow path 17 formed inside the welding torch 10 together with a carrier gas such as argon.

[0016] The components of the powder 3B as a welding material are not particularly limited, and in addition to metals, can include ceramics and the like. As the powder 3B in the present embodiment, among the shaping materials, powders containing materials and elements that are difficult to process into welding wires (for example, difficult-to-process elements such as W) can be exemplified. The diameter of the powder 3B is desirably 1000 μm or less, preferably 500 μm or less, from the viewpoint of the transportability by the carrier gas.

[0017] The welding torch 10 includes a substantially cylindrical torch body 11 and a tapered nozzle portion 12 provided at its tip. As shown in FIG. 2, inside the torch body 11, at a position near the nozzle portion 12, a contact tip 13 is provided. The contact tip 13 has a wire insertion hole 13a, and functions as a component that guides the welding wire 3A toward the workpiece W and also functions as a current-carrying component that supplies power to the welding wire 3A. It is formed of a metal material having electrical conductivity such as copper. The welding wire 3A extending downward from the contact tip 13 in the figure passes through the wire outlet 15 provided at the tip of the nozzle portion 12 and extends toward the welding region (including the molten pool 7 and the periphery of the molten pool 7) of the workpiece W to be welded, and an arc 5 is generated between the tip of the welding wire 3A and the workpiece W.

[0018] Inside the welding torch 10, a powder flow path 17 extending in the axial direction of the welding torch 10 is formed in a manner surrounding the contact tip 13 and the periphery of the welding wire 3A. The powder flow path 17 opens at the tip surface of the nozzle portion 12, and such an opening is defined as a powder discharge port 18. The powder 3B sent into the welding torch 10 together with the carrier gas from the powder supply device 44 flows through the powder flow path 17 and is then discharged from the powder discharge port 18 toward the arc 5.

[0019] Further outside the powder flow path 17, a shield gas flow path 20 extending in the axial direction of the welding torch 10 is formed in a manner surrounding the powder flow path 17. The shield gas flow path 20 opens at the tip surface of the nozzle portion 12, and such an opening is defined as a shield gas ejection port 21. The shield gas sent into the welding torch 10 from the shield gas supply device 40 flows through the shield gas flow path 20 in the welding torch 10 and is then ejected downward in the drawing from the shield gas ejection port 21. The shield gas ejected from the shield gas ejection port 21 surrounds the arc 5 to block the atmosphere, suppress oxidation, nitriding, etc. of the welding bead 6, and also plays a role in stabilizing the arc 5.

[0020] FIG. 3 is a cross-sectional view of the tip of the nozzle portion 12 in the welding torch 10. As shown in the figure, in this embodiment, an annular powder discharge port 18 is formed concentrically with the wire protrusion port 15 provided at the center of the nozzle portion 12. Further outside the powder discharge port 18, an annular shield gas ejection port 21 is formed concentrically with the wire protrusion port 15 and the powder discharge port 18. In the welding torch 10 configured in this way, the powder 3B as a welding material can be supplied to the welding area without being hindered by the shield gas.

[0021] In FIG. 1, the workpiece W located below the welding torch 10 is supported by a pedestal 50. This pedestal 50 is movable in three-dimensional directions by a driving device 51. The welding torch 10 and the workpiece W are relatively moved by the driving device 51, and a welding bead 6 is formed along such a relative movement direction.

[0022] As shown in Figure 1, the control unit 55 is connected to a wire supply device 30, a welding power supply 35, a shielding gas supply device 40, a powder supply device 44, a carrier gas supply device 47, and a drive device 51. The control unit 55 manages a series of operations related to additive manufacturing by controlling these devices. The control unit 55 can be configured using, for example, an information processing device equipped with a CPU, RAM, HDD, and various interfaces, or dedicated hardware. In the control unit 55, if welding conditions for obtaining the desired bead shape (specifically, its height and width) are pre-recorded in a database, the path of the weld bead during additive manufacturing can be derived based on the data of the target object.

[0023] Next, a method for manufacturing a three-dimensional object using the additive manufacturing apparatus 1 described above will be explained. First, data of the object created using separate 3D CAD software is acquired, and slice data for the Z-axis of the object is created. Then, the weld bead path is derived based on the slice data.

[0024] Next, the welding torch 10 is moved relative to the welding material, welding wire 3A and powder 3B, while melting them to manufacture an additively fabricated object. Specifically, while supplying the welding wire 3A and flowing shielding gas, an arc is generated to melt and solidify the welding wire 3A and the powder 3B supplied to the welding area, thereby stacking multiple layers of welding beads 6 on the base 50 to manufacture the target object.

[0025] In this embodiment, the amount of powder 3B supplied to the welding area can be changed depending on which part of the fabricated object the weld bead 6 directly below the welding torch 10 corresponds to, thereby altering the composition of a part of the fabricated object relative to the composition of other parts of the fabricated object. It is also possible to determine which part of the fabricated object the weld bead 6 directly below the welding torch 10 corresponds to based on the elapsed time since the start of additive manufacturing, the cumulative length of the weld bead, etc. For example, if powder 3B is composed of high-strength elements (such as W) that are difficult to process into welding wire, and the weld bead directly beneath the welding torch corresponds to the outer surface of the fabricated object, supplying more powder 3B to the welding area can increase the strength of the outer surface of the fabricated object.

[0026] As described above, with the welding torch 10 and additive manufacturing apparatus 1 of this embodiment, a welding bead 6 can be formed using both the welding material supplied to the welding area in the form of welding wire 3A and the welding material supplied to the welding area in the form of powder 3B. Therefore, even when performing additive manufacturing with welding materials containing materials or elements that are difficult to process into welding wire, the materials or elements that are difficult to process into welding wire can be made into powder 3B, while the materials or elements that can be processed into welding wire can be made into welding wire 3A, and this can be used as a consumable metal electrode. This allows for more efficient manufacturing of the fabricated object compared to when the entire amount of welding material is in powder form. Here, since the powder discharge port 18 is formed inside the shielding gas outlet 21 together with the wire protrusion port 15, the powder 3B as the welding material can be supplied to the welding area without being obstructed by the shielding gas.

[0027] Furthermore, the additive manufacturing apparatus 1 including the welding torch 10 of this embodiment is equipped with a powder supply device 44 that has means for changing the amount of powder 3B supplied to the welding area. During additive manufacturing, the amount of powder 3B supplied to the welding area can be changed according to which part of the manufactured object the welding bead 6 directly below the welding torch corresponds to, thereby changing the composition of a part of the manufactured object relative to the composition of other parts of the manufactured object.

[0028] Although embodiments of the present invention have been described in detail above, this is merely an example. For example, while an annular powder outlet is used in the above embodiment, a non-annular shielding gas outlet may be used as long as it is formed inside the shielding gas outlet and can supply powder to the welding area without being obstructed by the shielding gas. Also, in the above embodiment, the base supporting the workpiece is moved, but it is also possible to configure the system to form a linear welding bead by moving the welding torch side, and so on. The present invention can be implemented in various modified forms without departing from its spirit. [Explanation of symbols]

[0029] 1. Additive manufacturing device 3A welding wire (welding material) 3B Powder (Welding Material) 5 Arc 6. Weld bead 10 Welding Torches 13 Contact Tips 15 Wire protrusion 17 Powder flow path 18 Powder outlet 20 Shielding gas flow path 21 Shield gas nozzle 44 Powder feeding device W Workpiece

Claims

1. A welding torch that generates an arc between a welding wire and a workpiece to melt and solidify the welding material including the welding wire, A contact tip that supplies power to the welding wire and guides the welding wire toward the welding area through a wire protrusion port provided at the tip of the torch, A powder channel is provided at the tip of the torch to discharge powder, which is used as a welding material, toward the arc. A shielding gas flow path that supplies shielding gas around the arc through a shielding gas nozzle provided at the tip of the torch, Equipped with, A welding torch in which the wire protrusion port and the powder discharge port are formed inside the shielding gas nozzle at the tip of the torch.

2. A method for additive manufacturing, comprising using an additive manufacturing apparatus including a welding torch as described in claim 1, forming a layer of welding beads on the target surface of a workpiece, and stacking the welding bead layers to obtain a molded object of a predetermined shape.

3. The additive manufacturing apparatus includes means for changing the amount of powder supplied to the welding area, The additive manufacturing method according to claim 2, wherein the amount of powder supplied to the welding area is changed according to which part of the fabricated object the welding bead directly below the welding torch corresponds to, thereby obtaining a fabricated object of a predetermined shape.

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