JP2570338B2 - Metal surface treatment method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for treating a metal surface, and more particularly to a method for treating a metal surface by irradiating the metal surface with a beam from a high-density energy source. Things.

(Prior art) Conventionally, heat resistance is required for parts requiring heat resistance such as between valve seats of an aluminum alloy cast cylinder head of an internal combustion engine and parts requiring wear resistance such as a piston ring groove. In order to improve the abrasion resistance, etc., see JP-A-61-1937.
No. 73 discloses a method of using a high-density energy beam such as a TIG arc, a laser beam, or an electron beam to locally heat the surface of an aluminum alloy substrate, re-melt the aluminum alloy substrate, and rapidly solidify it. Proposed.

In Japanese Patent Application Laid-Open No. 62-38786, at that time, Fe, Co,
It has been proposed to arrange one or more alloying materials of V, Zr, and Ce in the form of powder, slurry, or the like, and locally alloy an aluminum alloy cylinder head.

[Problems to be solved by the invention]

In the above-described method for treating a metal surface, as shown in FIG. 2, while irradiating the surface of an aluminum alloy substrate 1 with a high-density energy beam 2 such as a TIG arc, a laser beam, an electron beam, or the like, Move 2 Beam 2
A re-melted portion and a rapidly solidified portion are sequentially formed on the surface of the substrate 1 that has been hit. At this time, the irradiated portion of the base material 1 receives the kinetic energy of the high-density energy beam 2 in a molten state, so that the melted base material 1 is pushed to the periphery to form the concave portion 3. The concave portion 3 is successively filled with the molten metal by the movement of the beam 2 and becomes a processing portion 4. However, the surface processing portion 4 of the base material 1 on which the re-melting and the rapid solidification treatment has been completed is provided in FIG. As shown, a convex portion 5 is formed at the irradiation start position of the beam 2,
At the irradiation end portion, the concave portion 3 is not completely filled,
The recess 6 having the depth d remains.

Since the projections 5 can be removed by a later machining process, they do not become a particular obstacle, but the depressions 6 are left in the product as underfill and are harmful.

The occurrence of the underfilling is a phenomenon peculiar to the melting by the high-density energy beam 2 and the rapid solidification treatment. As a solution to this problem, irradiation of the base material 1 is performed even after passing through the region where the treatment is required. At this time, the depth of the concave portion 3 accompanying the melting of the substrate surface was gradually reduced by increasing the relative moving speed of the substrate 1 and the beam 2 or decreasing the output of the beam, and the processing was completed. Methods that minimize the depth d of the concave portion 6 remaining in the state can be considered. However, in these methods, a pinhole is easily generated in a shallow melted portion, and this point becomes a new defect.

An object of the present invention is to solve the above problems and to provide a metal surface treatment method in which a concave portion does not occur at an irradiation end portion of a treated substrate surface.

[Means and actions for solving the problems]

The present invention provides a method of irradiating a metal surface with a beam from a high-density energy source relative to the metal surface to irradiate a local metal surface in an inner portion that does not include an edge of the entire surface. Control to irradiate the projecting part generated at the irradiation start part of the beam on the metal surface,
This is a method for treating a metal surface in which irradiation of a beam is terminated in a state where the convex portion is re-melted.

When a beam from a high-density energy source is relatively moved and irradiated on the metal surface, a molten portion and a rapidly solidified portion are sequentially formed on the surface of the metal to be processed hit by the beam. At this time, since the irradiating portion of the beam receives the kinetic energy of the high-density energy beam in a molten state, the molten metal to be processed is pushed to the periphery to form a concave portion and a convex portion around the concave portion. The concave portion is successively filled with the molten metal by the movement of the beam, and the surface of the metal to be processed after the irradiation of the beam returns to the vicinity of the original surface of the molten metal and rapidly solidifies.

After moving the beam or the metal body to be processed or the beam and the metal body to be processed, and after processing the surface of the predetermined area, the beam and the metal body to be processed are moved so that the beam returns to the start portion of the processing of the metal to be processed. Control. In other words, the irradiation start position and the irradiation end position of the beam on the metal to be processed are made to substantially match each other.

At the beam irradiation start site on the metal to be processed, there is a protrusion formed by the beam, so at the end of beam irradiation, this protrusion is irradiated and re-melted, and a large amount of molten metal is emitted. The irradiation of the beam is stopped in the state where it is present, and the surface of the metal to be treated returns to almost the level of the original surface and rapidly solidifies in that state.

Therefore, a convex portion at the beam irradiation start portion and a concave portion at the beam irradiation end portion are not formed on the metal surface on which the treatment has been completed, and the occurrence of underfill in the product is prevented.

〔Example〕

FIG. 1 is an explanatory view showing an example of relative movement control between a beam and a metal object to be processed according to the present invention.

A high-density energy beam 2 such as a TIG arc, a laser beam, an electron beam, etc. is applied to a local surface inside an edge portion of an aluminum alloy casting base material 1 such as an aluminum alloy cylinder head.
The substrate 1 or the beam 2 is moved while irradiating. The surface of the substrate 1 hit by the beam 2 is heated and melted, and receives the kinetic energy of the high-density energy beam 2 in a molten state, so that the melted substrate 1 is pushed to the periphery to form a concave portion as shown in FIG. 3 and a convex portion is formed around it.

In FIG. 1 (A), the beam 2 is moved from the irradiation start site S on the substrate 1 in the direction of the arrow, and is moved from the end of the processing area so as to return to the original direction.
Along with the movement of the beam 2, the concave portion 3 formed by the beam 2 is successively filled with a molten metal, returns almost to the vicinity of the original surface, and is rapidly cooled and solidified to become the processing section 4 where the processing is completed.

Since the projection 5 shown in FIG. 3 is formed at the irradiation end portion of the beam 2, that is, the irradiation start portion S of the beam 2, the projection 5 is irradiated and re-melted at the irradiation end portion of the beam. Then, it flows into and fills the concave portions 3 formed on the surface of the substrate 1. When the irradiation of the beam 2 is stopped in this state, the surface of the substrate 1 is filled with the molten metal to substantially the same level as the original surface, and rapidly solidifies in that state.

Instead of moving the beam 2, the substrate 1 may be moved.

FIG. 1 (B) shows an example of the control of the relative movement between the beam and the substrate 1 when the processing area is large. The beam is moved from the irradiation start site S in the X direction, and the beam is moved in the Y direction at the point a. Then, the beam is moved to the point b, and then moved in the reverse direction in the X direction. Such a movement of the beam is repeated to process the desired area, and finally, the beam returns to the irradiation start site S.

Similarly, the beam shown in FIG. 1 (C) returns to the irradiation start site S when the processing is completed from the irradiation start site S, but the beam is moved in the X direction and moved in the Y direction. May be controlled to move the substrate.

This method can be similarly used when one or more alloying materials are disposed on a substrate in the form of powder, slurry, or the like, and the substrate is locally alloyed.

In addition, although an aluminum alloy casting has been described as an example, the present invention is not limited to this, and can be used for treating a metal surface.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION This invention prevents the generation | occurrence | production of the underfill in the beam irradiation completion site | part which is a peculiar phenomenon in the local surface treatment of the metal by a high density energy beam, and improves the product yield.

[Brief description of the drawings]

1 (A), 1 (B), and 1 (C) are explanatory views showing examples of relative movement control between a beam and a metal object to be processed according to the present invention, and FIG. 2 is a cross-sectional view illustrating a state of surface treatment. FIG. 3 is a cross-sectional view for explaining a state where the conventional surface treatment is completed. 1: Base material 2: High-density energy beam 3: Concavity by high-density energy beam 4: Treated part 5: Convex part remaining on treated surface 6: Depressed part remaining on treated surface

Claims (1)

(57) [Claims] 1. A method for irradiating a metal surface with a beam from a high-density energy source relative to the metal surface to irradiate a local metal surface in an inner portion not including an edge of the entire surface. Control the beam irradiation end part to irradiate the convex part generated at the beam irradiation start part on the metal surface,
A method for treating a metal surface, comprising ending beam irradiation in a state in which the convex portion has been re-melted.