JPS6137916A - Heat treatment - Google Patents

Abstract

PURPOSE:To make the whole surface of a cam undergo uniform wear by dividing a beam scanning zone into plural parts and setting the scanning start points and finish points so that they do not meet each other when the cam is heat treated by irradiation. CONSTITUTION:A laser beam 9 is reflected by a reflecting mirror 8 and irradiated on the surface of the cam 2 of a can shaft 1 to be heat treated. At this time, conventional one beam scanning zone is divided into two parts, and the heating start points 5a, 6a and finish points 5b, 6b are set so that they do not meet each other. Two heat treated parts 5, 6 are formed, and untreated intermediate parts 4 are not in a row in the axial direction of the shaft 1, so the concentration of untreated parts on the cam 2 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of heat treating the surface of metal or other materials using a high energy density beam such as an electron beam or a laser beam.

[Prior art]

When using a high energy density beam to heat the surface of a shaft-shaped object to be heated by scanning the beam over the entire circumference, heating is performed such that the scanning start point and scanning end point of the beam scanning band overlap. If this method is used, if the material is cast iron, cracks may occur in the overlapping parts. In order to avoid this, if heating is performed so that the scan start point and scan end point do not overlap, there is a risk that the intermediate portion will be heat-treated and remain. Figure 2 shows an example of heat treatment performed using the conventional method, in which a beam is irradiated onto the cam portion (2) of the cam shaft (1), and a heat treated portion (3) is formed on the surface of the cam (2). However, at the same time, the unheated part (
It is also clear that 4) remains. FIG. 6, which is a partial sectional view taken along the line A--A in FIG. 2, shows this fact even more clearly. This unheated part (4) is generated because the scanning start point (3a) and end point (3b) are heated in the axial direction of the cam as described above during beam scanning so that the scanning start point (3a) and end point (3b) are subjected to gravity. They occur concentrated in a 1.1 lid shape with a certain width. This unheated part (4) t:j is a weak point on the cam surface, for example, (4) of the cam.
It had the disadvantage that only the parts wore out quickly.

[Summary of the invention]

The present invention was made in order to improve the drawbacks of the conventional method.
Instead of completing heating by beam scanning in just one round of a large beam scanning band, the beam scanning is performed on the part to be heat treated by dividing it into multiple beam scanning bands, and the scanning of each scanning band is repeated. By shifting the start point and end point so that they are not located on the same axis, the heat-treated first part (4) is prevented from being aligned on the same axis in the axial direction, thereby reducing weak points on the cam. Summary: This is an attempt to provide a heat treatment method that prevents this.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention. In the figure (1), (2
+, (4) are the same as the conventional method. (5) and f6) are heat-treated parts heated and formed by beam irradiation, (7) is a condenser lens, (8) is a reflecting mirror, and (9) is a laser beam.

The laser beam (9) is irradiated onto the surface of the cam (2) of the cam shaft (1) of the waste heat treated material after passing through the reflecting mirror (8) and the condensing lens (force). The band is divided into two and irradiated.(5L(6)Fi The beam irradiation band, that is, the heat treatment part, is the heating start point (5a), (6a) and end point (5b), (
By shifting the positions of 6b) as shown in the figure, it is possible to ensure that the intermediate portions (4) are lined up on the same line in the axial direction, and to prevent the unheated portions from concentrating on the cam. .

In the above example, there are two beam scanning bands, but the number may be six or more.

〔Effect of the invention〕

As mentioned above, when heat-treating a cam, by dividing the beam scanning band into multiple irradiation bands and shifting the scanning start and end points from each other, the unprocessed parts are lined up in the axial direction and concentrated. Since weak points are prevented from being present in the cam, excellent effects can be obtained in that weak points are scattered and wear is made uniform over the entire surface of the reversing cam.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the heat treatment process according to the present invention, FIG. 2 is a perspective view of a camshaft heat treated by a conventional method, and FIG. 6 is a sectional view thereof. In the figure, (4) is the unheated part, (5) and (6) are the beam scanning force, that is, the heat treated part, (the force is the condenser lens, and (8)
) is a reflecting mirror, and (9) is a laser beam. Note that the same reference numerals in each figure indicate the same or contrasting parts. Agent Patent Attorney Sanro Kimura 2nd Figure Flute 2 L Moe - To Q - Le A Kyo

Claims (1)

[Claims] In an apparatus that performs heat treatment on a shaft-like or cylindrical material to be heated by heating or surface melting using a high-energy density beam such as a laser beam or an electron beam, two or more beams are installed on the surface of the material to be heated. 1. A heat treatment method comprising: a beam scanning band, and scanning the beam so that the scanning start and end points of the beam scanning bands are not aligned on the same axis.