JP7100488B2 - Overlay welding method - Google Patents

Description

The present invention relates to a overlay welding method and an overlay weld obtained by this overlay welding method. The present invention also relates to a method for manufacturing parts using the overlay welded product.

Conventionally, MIG (Metal Inert Gas) welding, TIG (Tungsten Inert Gas) welding, LMD (Laser Metal Deposition) and the like have been used for overlay welding. Of these, in TIG welding and LMD, the surface of the work and the tip of the welding wire are melted by a heat source (arc or laser) to form a molten pool, while the welding wire is supplied to the molten pool from a direction different from the heat source.

Some welding wires for overlay include a center line and at least one outer peripheral line (see, for example, Patent Documents 1 and 2). For example, when there is one outer peripheral line, the center line is arranged inside the hollow outer peripheral line. When there are three or more outer peripheral lines, the outer peripheral lines are twisted together and the center line is arranged inside the outer peripheral lines. By using such a welding wire, an overlay bead having an arbitrary alloy composition can be formed depending on the composition of the center line and the composition of the outer peripheral line.

Japanese Unexamined Patent Publication No. 2009-221602 Japanese Unexamined Patent Publication No. 8-103888

By the way, when overlay welding is performed by TIG welding or LMD, the welding wire may be heated by energization in order to reduce the amount of heat input to the work (so-called hot wire method). In such a hot wire method, when a welding wire including the center line and at least one outer peripheral line as described above is used, both the center line and the outer peripheral line are heated by Joule heat when the welding wire is energized. , It is necessary to prevent melting of the center line and the outer circumference line. The overlay welding described in Patent Documents 1 and 2 does not use the hot wire method.

Therefore, an object of the present invention is to provide a build-up welding method capable of preventing melting of the center line and the outer peripheral line of the welding wire due to Joule heat.

In order to solve the above problems, the overlay welding method of the present invention comprises a step of melting the surface of the work and the tip of the welding wire with a heat source to form a molten pool, and heating the welding wire by energization. The welding wire includes a center line and at least one outer peripheral line, and the melting point of the outer peripheral line is 300 ° C. or higher higher than the melting point of the center line. Further, it is characterized by using a wire in which a resistance layer that inhibits electrical conduction from the outer peripheral line to the central line is interposed between the center line and the outer peripheral line.

According to the above configuration, since the melting point of the outer peripheral line to which the voltage is applied is set to be 300 ° C. or higher higher than the melting point of the center line, it is possible to prevent the outer peripheral line from melting due to Joule heat. Moreover, the resistance layer interposed between the outer peripheral line and the center line suppresses the heat of the outer peripheral line from being conducted to the center line even when the temperature of the outer peripheral line becomes higher than the melting point of the center line. Therefore, it is also prevented that the center line is melted by heat conduction. Further, since the resistance layer inhibits the electrical conduction from the outer peripheral line to the center line, the Joule heat generated in the center line when the welding wire is energized can be suppressed to a small value. This makes it possible to prevent the center line from melting due to Joule heat.

The resistance layer may be an air layer. According to this configuration, since the electrical resistivity of the resistance layer becomes remarkably large, the Joule heat generated in the center line when the welding wire is energized can be suppressed to be extremely small.

For example, the weld wire may be a stranded wire containing at least three of the outer peripheral wires twisted together.

For example, the diameter of the center line may be less than the diameter of the inscribed circle of the outer peripheral line in the cross section of the weld wire.

The composition of the center line and the composition of the outer peripheral line are such that the composition of the welding wire as a whole is expressed in mass percent as Cu: 60 to 85%, Sn: 5 to 15%, Pb: 2 to 20%. It may be adjusted to be. According to this configuration, the overlay bead can be composed of lead bronze, and the overlay bead can be imparted with lubricity.

The center line may contain Pb as a main component, and the outer peripheral line may contain Cu as a first main component and Sn as a second main component. Since lead bronze has poor ductility, it is difficult to manufacture a single wire made of lead bronze. On the other hand, if a single wire made of lead and a single wire made of bronze, which are on the market, are used as the center line and the outer peripheral line, respectively, the welded wire can be easily manufactured at low cost.

The center line may contain not only Pb but also Sn as a main component. According to this configuration, a single wire made of solder can be used as the center line.

The heat source may be a laser. According to this configuration, overlay welding can be performed by LMD.

The present invention also provides an overlay weld obtained by the overlay welding method described above.

Further, the present invention provides a part manufacturing method for manufacturing a part by machining the above-mentioned overlay weld.

According to the present invention, it is possible to prevent melting of the center line and the outer peripheral line of the welding wire due to Joule heat.

It is a figure for demonstrating the overlay welding method which concerns on one Embodiment of this invention. It is a figure for demonstrating the structure of the welding wire used in the said embodiment. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. It is a figure for demonstrating the structure of the welding wire of the modification. It is sectional drawing along the VV line of FIG.

With reference to FIG. 1, the overlay welding method according to the embodiment of the present invention will be described. In this embodiment, overlay welding is performed by LMD. That is, the laser 3, which is a heat source for melting, is irradiated toward the surface of the work 1 from the laser emission port shown in the figure.

The material of the work 1 is not particularly limited, but is, for example, steel, cast iron, stainless steel, a nickel-based alloy, an aluminum alloy, or the like.

In the overlay welding method of the present embodiment, the surface of the work 1 and the tip of the weld wire 2 for overlay are melted by the laser 3 to form a molten pool 10, while the weld wire 2 is melted from a direction different from that of the laser 3. It is supplied to the pool 10. Further, in the present embodiment, the welding wire 2 is supplied to the melting pool 10 while being heated by energization.

The welding wire 2 is fed through the nozzle 4. The nozzle 4 also serves as an electrode for applying a voltage to the outer peripheral surface of the welding wire 2. By applying this voltage, a current flows from the nozzle 4 to the work 1 through the welding wire 2 and the molten pool 10, and the welding wire 2 is heated. It is desirable that the welding wire 2 is heated so that the temperature of the outer peripheral wire 22 described later is equal to or higher than the melting point of the center line 21 described later and lower than the melting point of the outer peripheral wire 22.

Further, the nozzle 4 is provided with an annular flow path 41 around the welding wire 2, and the inert gas 5 such as argon is supplied to the periphery of the molten pool 10 through the flow path 41. In addition, instead of the annular flow path 41, a plurality of flow paths scattered in the circumferential direction may be adopted.

The laser ejection port and the nozzle 4 (not shown) are moved relative to the work 1 along the planned line to be overlaid welded. As a result, the overlay bead 11 is formed.

In FIG. 1, the welding wire 2 is located in front of the laser 3 in the welding direction along the above-mentioned planned line (direction from left to right in FIG. 1), but their positional relationship is opposite. May be good. Alternatively, the weld wire 2 and the laser 3 may be located on both sides of the planned line described above. Further, the nozzle 4 may be provided with a light guide path for guiding the laser 3, and the laser 3 may be emitted from the nozzle 4 at a position different from that of the welding wire 2.

The laser 3 may be directly irradiated to the welding wire 2, but it is desirable that the laser 3 is not directly irradiated to the welding wire 2 as shown in FIG. In other words, it is desirable that the irradiation range of the laser 3 with respect to the molten pool 10 deviates from the supply position of the welding wire 2 with respect to the molten pool 10.

As shown in FIG. 2, the weld wire 2 includes a center line 21 and at least one outer peripheral line 22. In this embodiment, as shown in FIGS. 2 and 3, the weld wire 2 is a stranded wire. More specifically, the weld wire 2 includes six perimeter wires 22 twisted together. The center line 21 is arranged inside the outer peripheral line 22. However, the number of outer peripheral wires 22 in the stranded wire may be at least three.

The stranded wire may be compressed from the outside and crushed after the outer peripheral wires 22 are twisted together. That is, the cross-sectional shape of each outer peripheral line 22 may or may not be a perfect circle.

A resistance layer 23 that inhibits electrical conduction from the outer peripheral line 22 to the center line 21 is interposed between the center line 21 and the outer peripheral line 22. The electrical resistivity of the resistance layer 23 is preferably 1.0 × 10 ^-5 Ω · m or more, and more preferably 10 Ω · m or more. In this embodiment, the resistance layer 23 is an air layer.

More specifically, the diameter Dc of the center line 21 is less than the diameter Di of the inscribed circle of the outer peripheral line 22 in the cross section of the welding wire 2. When the cross-sectional shape of each outer peripheral line 22 is a perfect circle, the diameter Di of the inscribed circles of the six outer peripheral lines 22 is equal to the diameter Do of the outer peripheral line 22.

From the viewpoint of ensuring a sufficient thickness of the resistance layer 23, the diameter Dc of the center line 21 is preferably 90% or less, and 70% or less of the diameter Di of the inscribed circle of the outer peripheral line 22. Is more desirable.

When the number of the outer peripheral lines 22 is 7 or more and the cross-sectional shape of the outer peripheral line 22 is a perfect circle, the diameter Di of the inscribed circle of the outer peripheral line 22 is larger than the diameter Do of the outer peripheral line 22. In this case, the diameter Dc of the center line 21 may be equal to or larger than the diameter Do of the outer peripheral line 22.

As described above, since the diameter Dc of the center line 21 is set small so that a gap is formed between the center line 21 and the outer peripheral line 22, the center line 21 is partially set to the outer peripheral line 22 in the axial direction. Contact with any of. That is, the cross-sectional shape of the resistance layer 23 is annular at a position where the center line 21 does not contact the outer peripheral line 22, and is substantially C-shaped at a position where the center line 21 contacts the outer peripheral line 22.

The melting point of each outer peripheral line 22 is set to be 300 ° C. or higher higher than the melting point of the center line 21. The composition of the center line 21 and the outer peripheral line 22 is appropriately determined depending on what kind of alloy the overlay bead 11 is composed of. For example, examples of the alloy of the built-up bead 11 include lead bronze, aluminum bronze, bronze, brass, and nickel-aluminum alloy.

When the overlay bead 11 is composed of lead bronze, for example, the composition of the center line 21 and the composition of the outer peripheral line 22 indicate the composition of the welding wire 2 as a whole in terms of mass percent (hereinafter, the same), Cu: It is adjusted to be 60 to 85%, Sn: 5 to 15%, and Pb: 2 to 20%. In this case, the center line 21 contains Pb or both Pb and Sn as the main component, and the outer peripheral line 22 contains Cu as the first main component and Sn as the second main component.

When the overlay bead 11 is made of lead bronze, lubricity can be imparted to the overlay bead 11. Since lead bronze has poor ductility, it is difficult to manufacture a single wire made of lead bronze. On the other hand, when the center line 21 contains only Pb as the main component and the outer peripheral line 22 contains Cu and Sn as the main components, the center line 21 is a single wire made of lead and a single wire made of bronze, which are distributed on the market. And can be used as the outer peripheral line 22. Therefore, the welding wire 2 can be easily manufactured at low cost. Alternatively, when the outer peripheral line 22 contains Pb and Sn as main components, a single wire made of solder can be used as the center line 21.

For example, the composition of the center line 21 and the outer peripheral line 22 when the diameter Dc of the center line 21 is 70% of the diameter Di of the inscribed circles of the six outer peripheral lines 22 is as follows.

When the center line 21 contains only Pb as a main component, for example, the composition of the center line 21 is Pb: 99 to 100%, and the composition of the outer peripheral line 22 is Cu: 90 to 95% and Sn: 5 to 10%. be.

When the center line 21 contains both Pb and Sn as main components, for example, the composition of the center line 21 is Pb: 60 to 99% and Sn: 1 to 40%, and the composition of the outer peripheral line 22 is Cu: 87 to. 98%, Sn: 2 to 13%.

When the overlay bead 11 is made of lead bronze, P, Al, Si and the like may be contained as additives in at least one of the center line 21 and the outer peripheral line 22. P, Al, and Si have a strong affinity for oxygen and act as a deoxidizing agent during overlaying. Therefore, P, Al, and Si are added in order to suppress bubble defects derived from the oxide of the overlay bead 11.

When the overlay bead 11 is made of aluminum bronze, for example, the composition of the center line 21 and the composition of the outer peripheral line 22 are such that the composition of the welding wire 2 as a whole is Cu: 80 to 99% and Al: 1 to 20%. It is adjusted to be. In this case, the center line 21 contains Al as a main component, and the outer peripheral line 22 contains Cu as a main component.

When the overlay bead 11 is made of bronze, for example, the composition of the center line 21 and the composition of the outer peripheral line 22 are such that the composition of the welding wire 2 as a whole is Cu: 80 to 99% and Sn: 1 to 20%. Is adjusted to. In this case, the center line 21 contains Sn as a main component, and the outer peripheral line 22 contains Cu as a main component.

When the overlay bead 11 is made of brass, for example, the composition of the center line 21 and the composition of the outer peripheral line 22 are such that the composition of the welding wire 2 as a whole is Cu: 60 to 99% and Zn: 1 to 40%. Is adjusted to. In this case, the center line 21 contains Zn as a main component, and the outer peripheral line 22 contains Cu as a main component.

When the overlay bead 11 is made of a nickel-aluminum alloy, for example, the composition of the center line 21 and the composition of the outer peripheral line 22 are such that the composition of the welding wire 2 as a whole is Ni: 90 to 99%, Al: 1 to 5%. It is adjusted to be. In this case, the center line 21 contains Al as a main component, and the outer peripheral line 22 contains Ni as a main component.

By the overlay welding method described above, an overlay weld including the overlay bead 11 can be obtained. From this overlay weld, it is also possible to machine the overlay weld to manufacture parts.

As described above, in the overlay welding method of the present embodiment, the melting point of the outer peripheral line 22 to which the voltage is applied is set to be 300 ° C. or higher higher than the melting point of the center line 21, and therefore the outer peripheral line 22 due to Joule heat is set. Can be prevented from melting. Moreover, the resistance layer 23 interposed between the outer peripheral line 22 and the center line 21 ensures that the heat of the outer peripheral line 22 is conducted to the center line 21 even if the temperature of the outer peripheral line 22 is higher than the melting point of the center line 21. Suppress. Therefore, it is also prevented that the center line 21 is melted by heat conduction. Further, since the resistance layer 23 inhibits the electrical conduction from the outer peripheral line 22 to the center line 21, the Joule heat generated in the center line 21 when the welding wire 2 is energized can be suppressed to a small value. This makes it possible to prevent the center line 21 from melting due to Joule heat.

(Modification example)
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, overlay welding may be performed by TIG welding. In this case, the heat source for melting is an arc.

Further, the welding wire 2 does not necessarily have to be a stranded wire including at least three outer peripheral wires 22. For example, the welding wire 2 may have a configuration in which the center line 21 is arranged inside one hollow outer peripheral line 22 (so-called hoop material).

Alternatively, as shown in FIGS. 4 and 5, the welding wire 2 has a configuration in which the center line 21 is covered with the resistance layer 23 and one or more outer peripheral wires 22 are wound around the resistance layer 23. May have (so-called winding). The resistance layer 23 in this case is made of, for example, a resin.

However, if the welded wire 2 is a stranded wire as in the above embodiment, there is an advantage that the alloy composition of the built-up bead 11 can be easily adjusted as compared with the hoop material. The parameter for adjusting the alloy composition of the overlay bead 11 when the materials of the center line 21 and the outer peripheral line 22 are determined is limited to the wall thickness of a single outer peripheral line 22 in the hoop material, whereas the stranded wire is used. This is because the diameter and twist pitch of the outer peripheral wire 22 can be used. Further, in the winding as shown in FIGS. 4 and 5, it is necessary to give the center line 21 the strength and flexibility of the welding wire 2, whereas in the winding, the center line 21 needs to have the strength and flexibility. There is no need to have sex. Moreover, if the resistance layer 23 is an air layer, the electrical resistivity of the resistance layer 23 becomes remarkably large, so that the Joule heat generated in the center line 21 when the welding wire 2 is energized can be suppressed to be extremely small.

1 Work 10 Melting pool 2 Welding wire 21 Center line 22 Outer line 23 Resistance layer 3 Laser (heat source)

Claims (8)

The process of melting the surface of the work and the tip of the welding wire with a heat source to form a molten pool,
A step of supplying the welding wire to the melting pool from a direction different from that of the heat source while heating the welding wire by energization is included.
The welding wire includes a center line and at least one outer peripheral line, the melting point of the outer peripheral line is 300 ° C. or more higher than the melting point of the center line, and the outer peripheral line is between the center line and the outer peripheral line. A overlay welding method using a wire having a resistance layer that inhibits electrical conduction from the center line to the center line. The overlay welding method according to claim 1, wherein the resistance layer is an air layer. The overlay welding method according to claim 1 or 2, wherein the welding wire is a stranded wire including at least three outer peripheral wires twisted together. The overlay welding method according to claim 3, wherein the diameter of the center line is smaller than the diameter of the inscribed circle of the outer peripheral line in the cross section of the welding wire. The composition of the center line and the composition of the outer peripheral line are such that the composition of the welding wire as a whole is expressed in terms of mass percent, Cu: 60 to 85%, Sn: 5 to 15%, Pb: 2 to 20%. The overlay welding method according to any one of claims 1 to 4, which is adjusted so as to be. The overlay welding method according to claim 5, wherein the center line contains 99 to 100% by mass of Pb, and the outer peripheral line contains 90 to 95% by mass of Cu and 5 to 10% by mass of Sn. 5. The center line contains 60 to 99% by mass of Pb and 1 to 40% by mass of Sn , and the outer peripheral line contains 87 to 98% by mass of Cu and 2 to 13% by mass of Sn . The overlaid welding method described. The overlay welding method according to any one of claims 1 to 7, wherein the heat source is a laser.

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