JP2001334378A - Method of welding cast iron with laser beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of welding cast iron with a laser beam welding, by which a cast iron and a steel member are welded with high reliability without need of a complicated control, a large sized welding head, or the like. SOLUTION: A pure Ni member 19 which is a foil whose thickness is 0.3 mm is inserted as an inserted member between a steel member 17 and a cast iron 18. The laser beam welding is performed while irradiating with the laser beam 1 from the side of the steel member 17. The Ni member 19 is located between the steel member 17 and the cast iron 19, thus the Ni member 19, melted behind a keyhole 8 generated by the radiation of the laser beam 1, is stirred by the upper part flow and the lower part flow in a molten pool 7 and distributed in the whole part of the upper and lower parts of the molten metal. Thus a stability and an elasticity of the structure after the high temperature welding are available throughout the whole molten zone of the metal due to the action of the Ni 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method using a laser, and more particularly, to a method for joining cast iron using a laser.

[0002]

2. Description of the Related Art It is extremely difficult to weld cast iron and steel with high reliability. When a commonly used mild steel welding wire is used to perform arc welding of cast iron and steel, the welding metal and The carbon in the cast iron diffuses into the deposited metal on the boundary with the cast iron, resulting in a very hard martensite structure.

When the deposited metal has a very hard martensite structure, the frequency of occurrence of welding cracks increases, the structure becomes poor in toughness, and the reliability of welding decreases.

Therefore, in the prior art, when welding of cast iron and steel is performed by arc welding, a method of performing arc welding using a pure nickel or iron nickel alloy-based welding wire is used.

[0005] The purpose of this is to improve the structure of the welded portion and obtain the stability and toughness after high-temperature welding by the nickel component.

[0006] For the arc welding, there is a method of welding cast iron and steel by laser. When the cast iron and the steel are welded by the laser, the welding process is rapidly quenched compared to the arc welding.

For this reason, when welding by laser,
The increase in hardness is greater than in arc welding, the toughness is significantly reduced, and the reliability of the weld is extremely low.

Therefore, when welding cast iron and steel by laser, a method is adopted in which welding is performed while feeding a welding wire of the above-mentioned pure nickel or iron-nickel alloy, as in arc welding. There is.

That is, as shown in FIG. 6, a laser 1 is irradiated from a nozzle 4 of a processing head portion 5 to a welding portion. At this time, a welding wire 2 of pure nickel or an iron-nickel alloy is fed. While welding method is adopted.

[0010]

However, in the case of the laser welding in the above-mentioned conventional technique, as shown in FIG.
Since the feeding cable 3 for adding the welding wire 2 to the processing head portion 5 is routed to add the welding wire 2 to the welding portion, the welding head portion becomes large, and the welding device becomes large.

In addition, since the feeding cable 3 is routed to add the welding wire 2 to the welded portion, a direction is generated in the welding, and it is necessary to control the welding direction and the feeding direction of the welding wire 2. However, the control becomes complicated.

Further, there arises a problem that the shape of the workpiece 6 to be welded is limited by the interference of the welding wire 2.

Further, when the steel material 6 and the cast iron material 6 'are welded, the flow of the molten metal around the keyhole 8 during welding, as shown in FIG. Occurs with

For this reason, as shown in FIG. 8, the nickel fed and added from above the melting pool 7 by the welding wire 2 has a main convection region at the upper part of the melting point, as shown in the part A, and the molten metal is added. At the bottom of the portion, the addition of nickel is small, and the effect of nickel for improving the structure is reduced.

Therefore, in a method of welding cast iron by laser, a welding method that improves the toughness of the welded portion and improves the reliability of welding without complicated control and enlargement of the welding head is desired. Was.

An object of the present invention is to realize a method for welding cast iron by laser welding, which can weld a cast iron and a steel material with high reliability without complicated control or enlargement of a welding head. That is.

[0017]

In order to achieve the above object, the present invention is configured as follows. (1) In a method of welding a cast iron by laser, in which a cast iron and a steel are overlapped and welded by a laser, a portion to be welded between the cast iron and the steel is filled with pure nickel or an iron-nickel-based alloy, and the above-mentioned portion to be welded By irradiating a laser beam, the cast iron and the steel are welded.

(2) Preferably, in the above (1),
A recess is formed in the portion to be welded of the cast iron or steel,
The recess is filled with the pure nickel or the iron-nickel alloy.

(3) Preferably, in the above (1) or (2), the pure nickel or iron-nickel alloy is in the form of a foil, a powder, or a paste.

According to the present invention, the joint between the cast iron and the steel is filled with foil or powder or paste of pure nickel or an iron-nickel alloy, and then irradiated with a laser to separate the cast iron and the steel. Complete joining.

Since pure nickel or an iron-nickel alloy material is located between steel and cast iron, the molten nickel behind the keyhole generated by the laser irradiation flows between the upper and lower flows of the molten pool. Is stirred by
It is distributed over the entire upper and lower portions of the molten metal.

This makes it possible to obtain the stability and toughness of the structure after high-temperature welding by the action of nickel on the entire molten metal portion.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for welding cast iron with a laser according to one embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic configuration diagram of a laser welding apparatus that performs a laser welding method according to one embodiment of the present invention.

In FIG. 1, a laser welding apparatus includes a laser oscillator 9 for oscillating a laser 1 and a laser power supply unit 10 for supplying power required for oscillation of the laser oscillator 9.
And

The laser 1 oscillated by the laser oscillator 9 is guided to a parabolic mirror 13 in the processing head 5 by a bending mirror 12 shown, and the laser 1 is collected on the surface of the work 6 by the parabolic mirror 13. It is illuminated and illuminated.

The work 6 is fixed on the XY table 16 by a work fixing jig 15, and the operation of the XY table 16 is controlled by the controller 11.

The controller 11 also controls the laser oscillator 9 and the laser power supply unit 10.

Further, the processing head 5 is fixed to a Z-axis (not shown), and can move up and down with respect to the work 6, and its operation is controlled by the controller 11.

Further, the laser welding apparatus is provided with a nozzle 4 for blowing a shielding gas near the area where the laser 1 is irradiated onto the workpiece 6, and argon, helium, nitrogen or the like is supplied from the nozzle 4 as a shielding gas. Work 6
Injected to.

The laser 1 is condensed and irradiated on the work 6 by the laser welding apparatus configured as described above, and the work 6 is moved by the XY table 16 to perform welding.

In the method for welding cast iron by laser according to one embodiment of the present invention, the work 6 to be welded is
As shown in FIG. 2, lap welding is performed using an SPCC material 17 having a thickness of 2 mm as a steel material as an upper plate and a spherical black smoke cast iron FCD450 material 18 having a thickness of 10 mm as a cast iron as a lower plate.

In one embodiment of the present invention, the steel 1
A pure nickel material 19 having a thickness of 0.3 mm is interposed between the cast iron 7 and the cast iron 18 as an insert material.

In the laser welding, the laser 1 is irradiated from the steel material 17 side, and the XY table 16 is moved to perform welding.

FIG. 3 is a diagram illustrating the flow of molten metal during welding using the laser welding method according to one embodiment of the present invention. In FIG. 3, since the nickel material 19 is located between the steel material 17 and the cast iron 19, the molten nickel material 1 is located behind the keyhole 8 generated by the irradiation of the laser 1.
Due to the flow of the upper part and the lower part of the molten pool 7, the molten metal 9 is distributed throughout the upper and lower parts of the agitated and molten metal.

As a result, nickel 1
The operation of No. 9 makes it possible to obtain the stability and toughness of the structure after high-temperature welding.

As shown in FIG. 4, a recess 20 is previously formed in a steel material 17 (upper plate) or a cast iron 18 (lower plate), and the recess 20 is filled with pure nickel or an iron-nickel alloy 19. I do. Then, the steel material 17 and the cast iron 18 may be laser-welded. Also in this case, it is possible to obtain the stability and toughness of the structure in the molten metal portion described above.

FIG. 5 shows a comparison between a case where a steel material and a cast iron are welded using the laser welding method according to one embodiment of the present invention and a case where the steel material and the cast iron are welded using the conventional laser welding method. It is a graph to do.

In FIG. 5, the vertical axis indicates the hardness (Hv) of the steel or cast iron, and the horizontal axis indicates the position (m) of the steel or cast iron.
m) shows a case according to an embodiment of the present invention in which a 0.4 mm nickel foil is inserted between a steel material and cast iron.

In FIG. 5, the line indicated by a black circle and the line indicated by a black square are those according to the prior art, and indicate the hardness on the cast iron side and the hardness on the steel material side, respectively.

The line indicated by a white circle and the line indicated by a white square are according to one embodiment of the present invention, and indicate the hardness on the cast iron side and the hardness on the steel material side, respectively.

As can be understood from FIG. 5, in both the cast iron and the steel material, in the range of about 1.5 to 3.5 mm, the hardness is higher in the case of the prior art than in the case of the present invention.

In the case of the prior art, there are cast irons exceeding 1000 Hv, and steel
Some are near v.

On the other hand, in the case of the present invention, both the cast iron and the steel material are at most around 350 Hv, and the increase in the hardness of the welded portion can be greatly suppressed as compared with the case of the prior art. It can be understood.

As described above, according to one embodiment of the present invention, a nickel material is filled or inserted between a cast iron and a steel material,
It is constructed so that the cast iron and the steel material are overlapped and welded by the laser.Therefore, no welding wire is required, and the cast iron and the steel material can be reliably connected without complicated control or enlargement of the welding head. A method for welding cast iron by laser welding that can be welded can be realized.

The pure nickel or iron-nickel alloy 19 inserted between the steel material 17 and the cast iron 18 is:
The same effect can be obtained by using a powder or a paste instead of a foil.

In the above-described example, the steel material 17 is used as the upper plate, the cast iron 18 is used as the lower plate, and the laser 1 is irradiated from the steel material 17 side to perform welding, but the cast iron 18 is used as the upper plate. The steel 1 is used as a lower plate, and the laser 1 is
The present invention can also be applied to an example of welding by irradiating.

[0047]

According to the present invention, in laser welding in which lap welding of steel material and cast iron is performed, pure nickel or iron-nickel alloy foil or powder or paste is welded to the steel material and cast iron at the portion to be laser-welded. It is configured to be filled and inserted during welding, so that the nickel component is distributed throughout the molten metal by the flow of the molten metal generated at the time of laser welding, to obtain a stable structure and good toughness of the welded part It is possible to join the steel material and the cast iron with high reliability.

Accordingly, it is possible to realize a method of welding cast iron by laser welding, which can weld a cast iron and a steel material with high reliability without complicated control and enlargement of a welding head.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a laser welding apparatus to which the present invention is applied.

FIG. 2 is a diagram showing a schematic configuration of a welding work in one embodiment of the present invention.

FIG. 3 is a view showing a state of a flow of a nickel component in a molten portion during laser welding according to one embodiment of the present invention.

FIG. 4 is a diagram showing another configuration example of the welding work according to the embodiment of the present invention.

FIG. 5 is a graph for comparing the hardness at the welded portion between the present invention and the prior art.

FIG. 6 is a view showing the periphery of a processing head when a welding wire is fed and welded during laser welding in the prior art.

FIG. 7 is a diagram showing a flow of a molten metal during laser welding according to the related art.

FIG. 8 is a diagram showing a region where a nickel component of a welding wire is agitated in a molten pool in a conventional technique.

[Explanation of symbols]

 Reference Signs List 1 laser 4 processing nozzle 5 processing head 6 processing work 7 melting pool 8 keyhole 9 laser oscillator 10 laser power supply 11 controller 12 bending mirror 13 parabolic mirror 15 work fixing jig 16 XY table 17 steel material 18 cast iron 19 pure nickel 20 recess

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toru Nakajima 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 4E068 BA06 BF00 DB01 DB05 DB14

Claims (3)

[Claims] 1. A method of welding a cast iron by laser in which a cast iron and a steel are overlapped and welded by a laser, wherein a portion to be welded between the cast iron and the steel is filled with pure nickel or an iron-nickel alloy. A method for welding cast iron with a laser, comprising irradiating a predetermined portion with a laser to weld the cast iron and steel. 2. A method for welding cast iron by laser according to claim 1, wherein a recess is formed in a portion of said cast iron or steel to be welded, and said recess is filled with said pure nickel or iron-nickel alloy. A method of welding cast iron by a user. 3. A method according to claim 1, wherein said pure nickel or iron-nickel alloy is in the form of a foil, powder, or paste. Welding method.