JPH0360595B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for overlaying a metal base material on a metal base material and an apparatus therefor for forming a build-up layer on the metal base material using metal powder.

Conventionally, as shown in FIG. 1, this type of overlaying method has involved supplying metal powder b onto a metal base material a, rotating it, and rapidly melting and solidifying it with a laser beam c. When overlaying is carried out using this method, boiling occurs in the molten pool due to oxidation of C, Cr, etc. in the components of metal base material a and metal powder b, resulting in problems such as blowholes and slag entrainment. It was happening. Incidentally, even if some blowholes are allowed, there are problems in that the surface has large irregularities, and this finishing process requires many man-hours and has a low yield.

The reason for this is that air is drawn in when the metal powder is supplied, and the oxygen in the air reacts chemically with C, Cr, etc. in the components of the metal base material a and the metal powder b. This is exactly the same even when the powder is molded in advance using a binder.

On the other hand, in addition to the method of depositing copper on a metal base material using a laser beam, as shown in Japanese Patent Publication No. 48-30541, copper is deposited on a metal base material using a plasma arc.
When overlaying is carried out using metal powder such as lead, there is a lot of reflection of the metal powder called licorice on the surface of the molten pool, and the metal powder often spreads out in all directions with the gas flow. However, there is a problem that the ratio of the weight of the formed overlay layer to the weight of the supplied metal powder, that is, the powder efficiency is poor.

This is because the supplied metal powder is accelerated at high speed by the intense plasma gas flow caused by the plasma arc, and the plasma gas flow spreads on the surface of the metal base material, which is the anode.

The present invention aims to solve the above-mentioned problems, and provides a method for overlaying on a metal base material that can form an extremely uniform and high-quality overlay layer while solving the above-mentioned problems. The goal is to provide equipment.

Next, specific embodiments of the method and apparatus for overlaying on a metal base material according to the present invention will be described with reference to the drawings.

In FIG. 2, reference numeral 1 denotes a metal base material placed on a rotary table (not shown), and a groove 6 for overlaying is provided on the upper surface of the metal base material 1. Reference numeral 2 denotes a supply pipe provided above the metal base material 1, and one end of this supply pipe 2 is open and is arranged to face the groove 6 in which the metal base material 1 is to be overlaid. There is. The supply pipe 2 is provided with a gas supply branch pipe 2a and a metal powder supply branch pipe 2b, each facing diagonally downward. A laser device (not shown) is connected to the other end of the supply pipe 2 so that the laser beam 3 passes through the axis of the supply pipe 2, and a gas supply branch pipe 2a is connected to the laser device (not shown). An inert gas supply device (not shown) further connects the metal powder supply branch pipe 2b.
A metal powder supply device (not shown) is connected to each.

The supply pipe 2 is then opposed to the groove 6 of the metal base material 1, and the metal base material 1 is rotated so that the groove 6 moves along the tip of the supply pipe 2. In this state, the laser device, inert gas supply device, and metal powder supply device are operated.

As a result, the laser beam 3 and an inert gas containing metal powder 5 for overlaying, such as argon gas 4
are coaxially formed and supplied from the supply pipe 2 to the groove 6 of the metal base material 1.

In this way, the metal powder 5 is exposed to argon gas 4.
It is melted by the laser beam 3 in an inert gas atmosphere and deposited in the groove 6.

In the above embodiment, the flow rate of argon gas, the inner diameter of the supply pipe 2, and the distance between the tip of the pipe and the metal base material 1 are set in the following ranges.

(1) Argon gas flow rate: 0.5 to 10/min (2) Inner diameter of supply pipe: If the overlay groove width is a
1.1a~3a (3) Distance between supply pipe tip and metal base material surface: 5a
Within the above range, if the flow rate of argon gas is less than the above range, the sealing will be insufficient, and if it is too much, the oxidation prevention effect will be lost due to air entrainment.
If the diameter of the supply pipe is smaller than 1.1a, the seal will be insufficient, and if it is larger than 3a, the gas flow will be disturbed and the seal will be insufficient. Furthermore, gas consumption increases. If the distance between the tip of the supply pipe and the surface of the metal base material is less than 5 mm, the argon gas will be disturbed and the oxidation prevention effect will be lost due to air entrainment.

In the above-described overlay method, the metal powder 5 for overlay is supplied onto the metal base material 1 coaxially with the laser beam 3 and the inert gas, so that the supply direction thereof is directed to the upper surface of the metal base material 1. The overlay work can be carried out without any problem even if it is slightly tilted. Further, the metal powder 5 is preheated within the supply pipe 2 for a relatively long time while being supplied coaxially with the laser beam 3.

According to the above embodiment, since the inert gas is always supplied together with the laser beam 3 and the metal powder 5, the melt build-up part can always be surrounded by a fresh inert gas atmosphere.

The metal powder for overlay used in both of the above examples was commercially available under the trade name Eatonite. Note that nitrogen gas may be used instead of argon gas.

The cross section of the built-up portion is shown in the enlarged photographs taken with a microscope shown in FIGS. 3 and 4. The photograph in FIG. 3 is the one obtained by the conventional method, and the one shown in FIG. 4 is the one according to this embodiment. As is clear from these two photographs, blowholes and slag entrainment are observed in the conventional one shown in Fig. 3, while the present example shown in Fig. 4 has no blowholes or slag entrainment, resulting in a good alloyed part. I was able to do that. Further, the surface irregularities were 0.5 to 1.0 mm in the conventional method, but in this example, an extremely smooth surface of 0.2 to 0.4 mm could be obtained.

Further, according to this embodiment, the metal powder 5 for overlay
By being coaxial with the laser beam 3 and the inert gas and being supplied onto the metal base material 1, the overlay work can be performed without any problem even if the supply direction is slightly inclined with respect to the top surface of the metal base material 1. can be done,
This makes it possible to efficiently perform build-up work in all directions within one plane.

Furthermore, according to this embodiment, the position of the path for supplying the metal powder 5 to the supply pipe 2, the supply amount of the metal powder 5, the laser output, the laser beam diameter on the surface of the metal base material, and the processing speed can be finely controlled. This makes it possible to control the preheating temperature of metal powder with high precision. For this purpose, the laser power, beam diameter, and processing speed are adjusted to suit the needs of low melting point base materials, e.g.
By setting conditions that do not excessively melt the Al base material and adjusting the amount of metal powder supplied and preheating temperature,
It is possible to preheat a high melting point metal powder, such as Stellite #6, to a high temperature and build it up without excessively melting a low melting point base material.

From the above, in short, the method for overlaying onto a metal base material according to the present invention is to supply an inert gas containing metal powder onto a metal base material from above in a supply flow path coaxially with respect to the supply flow path. The laser beam is positioned along the metal base material, and the metal powder is directly supplied to the molten pool formed by the laser beam on the metal base material.

Further, the overlaying device on a metal base material according to the present invention is provided with a supply pipe having an opening at one end for supplying an inert gas containing metal powder onto the metal base material, and at the other end of the supply pipe. A laser beam supply section is provided on the side so that the laser beam passes through the axial center of the supply pipe at least near the opening, and the metal powder is directly supplied to the molten pool formed by the laser beam on the metal base material. It is characterized by being supplied.

Therefore, according to the present invention, the following effects are achieved.

The metal powder is directly supplied to the molten pool formed by the laser beam without being disturbed by the plasma gas flow as in the case of plasma arc, and the metal powder is hidden in the molten pool. Gases including inert gases in between are reliably removed at the time of submersion, and intrusion of gases into the molten pool can be prevented.

Therefore, the metal powder is smoothly melted and solidified, and an extremely uniform and high-quality build-up layer is formed.

Since the metal powder is supplied onto the metal base material in the form of an inert gas containing metal powder, the metal powder is always melted with a laser beam under a fresh inert gas atmosphere. Therefore, no blowholes or slags are caused in the build-up part, and the surface is smooth, so the quality of the build-up layer and the processing yield after build-up are good.

A laser beam and an inert gas containing metal powder are supplied coaxially, and the metal powder is directly supplied to a molten pool formed by the laser beam on the metal base material. Therefore, (i) in the molten pool formed by the laser beam,
In order for the metal powder to be directly supplied without being disturbed by the plasma gas flow as in the case of plasma arc, and to be hidden in the molten pool, gases containing inert gas between the metal powders are It is reliably removed when it is submerged, and gases can be prevented from entering the molten pool.

(ii) Furthermore, the metal powder is preheated by a laser beam during supply, and the difference between the temperature of the metal powder and the temperature of the molten pool is alleviated, so that the metal powder is quickly integrated into the molten pool.

(iii) Furthermore, the surface of the molten pool is surrounded by an inert gas atmosphere, which prevents oxidation of the molten pool surface.

The effects described in items (i) to (iii) above work together to smoothly melt and solidify the metal powder, forming an extremely uniform and high-quality build-up layer.

In addition, the laser beam does not generate a strong airflow like a plasma gas flow, and as mentioned above, the metal powder is directly supplied from above into the molten pool formed by the laser beam. Very good powder effect.

Furthermore, as mentioned above, the metal powder is preheated during supply, and since this preheated metal powder is supplied to the molten pool, the temperature of the molten pool also rises, increasing the laser energy efficiency and increasing the overlay efficiency. good.

Further, according to the device according to the present invention, a device having the above-mentioned effects can be made compact and economical.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of the conventional method, Fig. 2 is an explanatory view showing an example of the method of the present invention, and Figs. , FIG. 3 shows the case according to the conventional method, and FIG. 4 shows the case according to this embodiment. 1 is a metal base material, 2 is a supply pipe, 2a, 2b are branch pipes, 3 is a laser beam, 4 is argon gas, 5
is metal powder.

Claims (1)

[Claims] 1. A laser beam is positioned coaxially with the supply channel of an inert gas containing metal powder onto the metal base material from above, and A method for overlaying onto a metal base material, characterized in that metal powder is directly supplied to a molten pool formed on the base metal by a laser beam. 2. The metal base material is moved relative to the supply flow path for the inert gas containing the metal powder, which is positioned in the supply path so that the laser beam is aligned coaxially with the metal base material. A method of overlaying onto a metal base material according to claim 1. 3. A hollow supply pipe with one opening facing the metal base material, a laser beam supply section disposed on the axis of the supply pipe and on the side of the other opening,
a metal powder and inert gas supply section disposed on the side between both openings of the supply pipe for supplying an inert gas containing metal powder onto the metal base material from a portion facing the metal base material; A device for overlaying onto a metal base material consisting of. 4. The overlaying device on a metal base material according to claim 3, characterized in that the metal base material is moved relative to the supply pipe.