JPH067996B2 - Laser overlay welding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser overlay welding method for forming a weld metal on the surface of a workpiece by melting a overlay metal with a laser beam.

[Prior Art] In order to improve the wear resistance of metal workpieces such as machine parts and to provide them with corrosion resistance, dissimilar metals such as wear-resistant alloys and corrosion-resistant alloys are applied to the surface of the workpieces. Overlay welding is performed. When a laser beam is used as a heat source for melting the overlay metal, a laser processing head is arranged above the work piece, and a laser beam focused between the laser processing head and the work piece is used. The overlay metal is melted.

As the overlaying metal used to impart wear resistance and corrosion resistance to the workpiece, cobalt-based alloys, nickel-based alloys, pearlite-based steels, martensitic steels, chrome steels,
Many types of manganese / austenitic steels, 16Mn-16Cr austenitic steels, high chromium iron alloys, tungsten carbide alloys and the like have been put to practical use.

Since these build-up metals are generally highly rigid and not flexible, it is difficult to form them in the form of thin wires, thin plates or foils and wind them up on reels. In particular, among cobalt-based alloys, stellite containing 30% chromium, 4-8% tungsten, 1% carbon, 2% iron, etc., tungsten carbide alloys, chromium carbides, etc. have excellent wear resistance, but the hardness of the metal structure is hard. Since it is large and has no flexibility, it is difficult to form it into a thin plate or a wire having a small diameter. Therefore, these high-hardness build-up metals had to be formed in the shape of a welding rod of about 30 cm to 1 m.

[Problems to be Solved by the Invention] As described above, in the conventional overlay welding method, when a high-hard overlay metal is used, the overlay metal must be formed in the shape of a welding rod. Therefore, the overlay metal cannot be automatically fed to the workpiece. Therefore, during welding, it is necessary to manually supply the overlay metal to the workpiece, and there is a problem that the welding speed is significantly reduced. In addition, there is a problem that it is difficult to make the thickness of the weld metal deposited evenly when the metal for overlay is manually supplied.

An object of the present invention is to improve the welding speed by enabling automatic feeding to the work piece of the overlay metal even when using a high-hard overlay metal, and the thickness of the deposited metal group. The object is to propose a laser overlay welding method that can achieve uniform welding.

[Means for Solving Problems] The present invention, as seen in FIG.
In the overlay welding method of melting the overlay metal 2 to form the deposited metal 3 on the surface of the workpiece 1, an amorphous continuous strip metal foil is used as the overlay metal 2, and the continuous strip metal foil is used. Is continuously and intermittently automatically fed to the non-working product 1, and the continuous strip-shaped metal foil is melted by the laser beam 4 to form the deposited metal 3.

[Advantageous Effects of the Invention] Since the overlay metal used in the conventional overlay welding method has a crystal structure, when the hard overlay metal is used, the overlay metal is a thin wire. It could not be formed into a thin plate or foil, and automatic feeding of the overlay metal was not possible. However, when the overlay metal is made amorphous like the present invention, it has flexibility and continuity. Since the build-up metal can be obtained in the form of a strip-shaped metal foil, it becomes possible to automatically feed this to the workpiece through the feeding mechanism. Therefore, the welding speed can be improved and the thickness of the deposited metal layer can be made substantially uniform.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings.

In the examples, an amorphous continuous band-shaped metal foil of nickel-based alloy and cobalt-based alloy was used as the overlay metal. The metal foil of the amorphous alloy can be obtained by a usual method of melting the material for the overlay welding metal and quenching it. The amorphous continuous strip metal foil obtained at present has a thickness of about 0.025 to 0.06 mm and a width of about 10 to 100 mm, and has extremely high flexibility and bending strength as compared with the conventional overlay metal having a crystal structure. Is also large. Therefore, the amorphous continuous strip-shaped metal foil can be wound on a reel and can be automatically fed to the workpiece through the feeding mechanism.

In FIG. 1, reference numeral 1 is a work piece, and 2 is a build-up metal composed of an amorphous continuous metal foil. The overlaying metal foil 2 is wound around a reel 5 and passes through a feeding mechanism 9 including a feeding roller 7 driven by an electric motor 6 and a pressure roller 8 and a guide member 10 to be processed 1 Is automatically fed to the surface of. A laser processing head 11 is arranged above the work piece 1, and the metal 2 for build-up is supplied to the surface of the work piece.
The laser beam 4 focused from the processing head 11 is irradiated to melt the overlay metal and the workpiece. Reference numeral 12 denotes a molten pool formed by the irradiation of the laser beam, and the overlaying metal 2 is guided by the guide member 10 to the molten pool 1
It is guided toward 2 and its tip is inserted into the molten pool. By moving the workpiece 1 and the laser beam 4 relatively, the molten pool 12 is moved, and the molten overlay metal is cooled and solidified to form the overlay weld metal 3.

The speed of the electric motor 6 is controlled by a control device (not shown) so as to keep the supply speed of the overlay metal in an appropriate range, and the overlay metal 2 is automatically fed continuously or intermittently by this motor.

FIG. 2 shows an example of a supply mechanism suitable for use in the method of the present invention. In this example, the feed roller 7 is formed in a substantially drum shape and has a shallow V-shape on the outer periphery of its body. Groove 7a is formed. The pressure roller 8 is formed in a substantially drum shape having a V-shaped convex portion 8b complementary to the V-shaped groove 7a on the outer periphery of the body of the feeding roller 7 on the outer periphery of the body. The overlaying metal 2 made of foil is plastically deformed when passing between the rollers 7 and 8 to be formed into a shape having a shallow V-shaped groove. In this case, of course, the shape of the feeding roller 7 and the shape of the pressure roller 8 may be interchanged.

Since the amorphous continuous strip metal foil is very thin, it easily deforms,
Moreover, since the deformation is not constant, there is a possibility that the thickness of the overlay deposition metal may vary. Therefore, when the strip-shaped metal foil is forcibly plastically deformed into a constant cross-sectional shape by using a feeding mechanism as shown in FIG. 2, the shape of the metal foil supplied to the surface of the workpiece is kept constant and the overlay is built up. It is possible to eliminate the possibility that the thickness of the deposited metal fluctuates.

In the above embodiment, the build-up metal consisting of the strip-shaped metal foil is automatically fed to the workpiece through the space between the feeding roller and the pressure roller, but it may be automatically fed by another method. May be. For example, as shown in FIG. 3, a build-up metal 2 made of a continuous strip of metal foil is spirally wound around a rotary cylinder 13 that is driven to rotate by a motor 6, and the build-up is performed while rotating the cylinder 13. Even if the working metal 2 is automatically fed to the workpiece 1, it is possible to perform the overlay welding with high efficiency and evenly.

When a laser beam is used as a heat source for heating and melting the overlay metal as in the present invention, the advantage of laser beam welding that fine processing can be easily performed, and overlay welding is performed efficiently be able to.

Also, since the laser beam is a high-output, high-energy-density heat source, if a laser beam is used as a heat source for overlay welding,
The melting can be performed rapidly to improve the wettability between the overlay metal and the base material, and local overlaying is possible. Further, since the laser beam can be accurately controlled in terms of time and space by an optical means or the like, the laser beam is oscillated in the width direction of the overlay metal 2 made of, for example, a continuous strip metal foil, so The whole metal can be heated uniformly. Therefore, when a laser beam is used, dilution of the overlay metal with the base material can be minimized and uniform melting can be obtained, and the properties of the overlay portion can be improved.

Further, when a laser beam is used as a heat source, heat input to the base material is small, so that distortion and deformation of the base material can be reduced.

There are various known methods for oscillating a laser beam, one example of which is shown in FIG. In the example shown in FIG. 4, the laser beam 4 generated from the laser oscillator 20 is focused on the workpiece 1 via the focusing mirror 21 and the oscillating plane mirrors 22 and 23, and the oscillating plane mirrors 22 and 23 are The laser beam 4 is oscillated to oscillate in the width direction of the overlay metal 2.

As the laser beam, one that is continuously generated may be used, or a pulsed laser beam may be used.

In each of the above-mentioned examples, the overlaying metal 2 is energized by applying a low voltage between the overlaying metal 2 made of a strip-shaped metal foil and the workpiece so as not to continuously generate an arc. Alternatively, the overlay metal can be preheated by resistance heating. If the preheating is performed in this manner, the thickness of the overlay welding metal formed on the surface of the workpiece can be increased without increasing the penetration depth of the surface of the workpiece 1.

[Advantages of the Invention] As described above, according to the overlay welding method of the present invention, the overlay metal is used in the form of an amorphous continuous strip-shaped metal foil.
Even if automatic feeding cannot be performed because the hardness is high in the state of having a crystalline structure and the shape of the welding rod is unavoidable, the overlay metal can be automatically fed. ,
There is an advantage that the overlay welding in which the thickness of the deposited metal is substantially uniform can be efficiently performed.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment in which the laser beam overlay welding method of the present invention is performed using an amorphous continuous strip metal foil as a overlay metal, and FIG. 2 is suitable for use in the method of the present invention. FIG. 3 is an explanatory view showing an example of a metal feeding mechanism for overlay welding, FIG. 3 is an explanatory view showing another embodiment of the present invention, and FIG. 4 is an explanation explaining a method of oscillating a laser beam during welding. It is a figure. DESCRIPTION OF SYMBOLS 1 ... Workpiece, 2 ... Overlay metal consisting of amorphous continuous strip metal foil, 3 ... Overlay weld metal, 4 ... Laser beam.

Claims (3)

[Claims] 1. A build-up welding method for forming a deposited metal on a surface of a workpiece by melting a build-up metal, wherein an amorphous continuous strip-shaped metal foil is used as the build-up metal. A laser overlay welding method of forming a weld metal by melting a continuous strip-shaped metal foil with a laser beam while automatically or continuously feeding the metal foil to the workpiece. 2. The laser overlay welding method according to claim 1, wherein the amorphous continuous strip metal foil is made of a cobalt-based amorphous alloy. 3. The laser overlay welding method according to claim 1, wherein the amorphous continuous strip metal foil is made of a nickel-based amorphous alloy.