JPS61235546A - Production of low-melting point metallic member - Google Patents

Abstract

PURPOSE:To give uniform heat treatment effect to the whole parts of alloy by making gradually the irradiation intensity of the heat rays small in case of melting the surface of low-m.p. metal such as Al alloy with the irradiation of the high-density energy heat rays and quenching it to form a finely-divided structure. CONSTITUTION:The high-density energy heat rays such as a laser beam 2 are irradiated on the surface of a low-m.p. alloy plate 1 such as Al alloy and the surface of the Al alloy plate 1 is locally melted and thereafter quenched. The wear resistance is increased because the metallic structure of the part to be treated is made dense and hardened. In such a case, since the adjacent part 1a wherein the heat rays are irradiated, melted and quenched is made to the high temp., the temp. of the part is measured with a thermocouple 3 buried in the transferring direction of the heat rays 2 and the intensity of the heat rays 2 is slowly made weak in accordance with the temp. or the transferring velocity of the heat rays 2 is made speedy and the heat rays 2 are scanned and irradiated so that the temp. hardly wholly reaches the prescribed heat- treating temp. or above and the uniform wear resistant hardening layer is formed on the whole surface of Al alloy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention irradiates a low-melting point metal member such as an aluminum alloy with a high-density energy hot ray such as a laser beam to locally melt and melt the surface of the metal member. The present invention relates to a method of manufacturing a low-melting point metal member in which the metal structure is refined by rapid cooling.

[Prior art]

A method of irradiating the surface of a metal component with high-density energy heat rays such as a laser beam to locally melt and rapidly cool it, thereby densifying and hardening the metal structure and improving the wear resistance of the metal component, is particularly effective. However, when the above method is applied directly to a low melting point metal member such as an aluminum alloy, it is necessary to keep the irradiation intensity of high-density energy hot rays constant and move the irradiation position while melting. If this is done, the temperature of the metal base material will rise significantly in the latter half of the moving irradiation compared to the beginning of irradiation, which will increase the thickness of the molten zone, and not only will the metal structure not be uniformly refined, but the molten zone will There are problems such as the surface becomes rough, the finishing process takes more time, and the dimensional accuracy of the product decreases.

[Purpose of the invention]

The present invention has been made in consideration of the above-mentioned problems in the conventional example, and is a method for locally melting and rapidly cooling a metal member by irradiation with high-density energy heat rays. It is an object of the present invention to provide a method for manufacturing a low-melting point metal member that can make the thickness of the melted part uniform and keep the roughness of the surface of the melted part low even when applied to the present invention.

[Structure of the invention]

The present invention provides a method for manufacturing a low-melting point metal member in which a low-melting point metal member is irradiated with high-density energy heat rays to locally melt and rapidly cool the metal structure to make the metal structure fine. The irradiation of the high-density energy heat rays is controlled so that the amount of heat of the metal member near the irradiation position of the heat rays is kept approximately uniform over the entire movement process, and as a result, the melted and rapidly cooled metal structure has a substantially uniform thickness. It is characterized by the fact that it is made to be.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 7.

This example uses aluminum alloy AC as a low melting point metal member.
Using a 8A (180X80X8'tm flat plate), as shown in Figure 1, this aluminum alloy was irradiated with a scanning laser beam 2 as a high-density energy hot ray, and the surface was locally melted and rapidly cooled. This method is applied to obtain aluminum alloy 1, and the temperature of the base material in the vicinity of the irradiation position (in this case, immediately in front of the irradiation position) of laser beam 2 moving on the surface of aluminum alloy 1 is sequentially detected. Laser beam 2 based on temperature
The irradiation intensity is controlled as the irradiation position moves. That is, once irradiation with the laser beam 2 is started, the temperature of the base material of the aluminum alloy 1 gradually rises, so the laser beam is increased by the amount that the base material temperature at the position where the beam is about to be irradiated has already increased. By repeating control such as keeping the irradiation intensity of beam 2 low, the sum of the amount of heat from laser beam 2 directly applied to the irradiation position and the amount of heat already stored in the base material at that irradiation position is The amount of heat suitable for local surface melting is kept approximately uniform throughout the entire irradiation process.

The base material temperature of each part of the aluminum alloy 1 is detected at a scanning distance of 5fl and 25* from the irradiation start point of the laser beam 2 within the irradiation section length of 55fl as shown in FIG.
3 thermocouples at each point of n, 45m...

By setting , temperature is detected discretely. The embedded depth of the thermocouple 3 is 2 mm from the surface of the aluminum alloy 1 with a thickness of 81 m.
The depth is H. Further, the output of the laser beam 2 at the start of irradiation is 3.9 KW.

At this time, data such as the output conditions of laser beam 2 and the detected temperature at each measurement point are shown in Table 1 (1).
It is shown in the column.

When using this method, the base material temperature near the molten part of aluminum alloy 1 increases only to about 350°C, and
As shown by diagonal lines in the figure, on the surface of aluminum alloy 1,
5 from the irradiation start point to the irradiation end point of laser beam 2
Melting is performed uniformly and under favorable temperature conditions over the entire irradiation section 511, the depth of the melted part 1a is uniform at approximately 1.5+n, and the surface roughness is also suppressed to a low level.

FIG. 4(A) and FIG. 4(B) respectively show a point at a scanning distance of 5fi from the irradiation start point in the above process and a point at a scanning distance of 45.
The graph shows the measurement results of the unevenness of the surface at the dragon point using a surface roughness meter.

The measurement direction of the surface roughness meter at this time is the direction indicated by symbol A in FIG. 5 with respect to the melted portion 1a.

In addition, in the above melting/quenching process, A is used as an assist gas.
"I am using 2.5 kg/cni, 501/min.

As a comparative example for this example, a sample 1' identical to the aluminum alloy 1 was irradiated with the laser beam under the laser beam irradiation conditions shown in Table 1 (21jl), that is, at a constant irradiation intensity (here, 3.9 KW/CIA). Fig. 6 shows the state of melting in the case of conventional scanning, and Fig. 7 (A) and Fig. 7 (B) show the unevenness of the surface at scanning distances of 5 and 45 points, respectively. ) is shown graphically.

As is clear from FIG. 3 showing the results of this example, in this example, as the temperature of the aluminum alloy 1 increases due to irradiation with the laser beam 2, the laser beam 2 increases.
The irradiation intensity is controlled to be low, and the amount of heat of the aluminum alloy 1 at the irradiation position is always kept approximately constant. Therefore, local surface melting is performed under approximately constant temperature conditions throughout the entire irradiation process, and the melting area 1a is The depth is also uniform. Furthermore, due to the above irradiation control, as shown in (1)+1i11 in Table 1, the temperature of the base material near the melted zone 1a increases by about 350°C at most, and since the melted zone 1a does not overheat, its surface The surface roughness can be kept low as shown in FIGS. 4(A) and 4(B).

Incidentally, in the conventional method, as shown in column (2) of Table 1 above, as the irradiation with the laser beam 2 progresses, the temperature near the melted part 1a' increases, and at a point 45 fins from the irradiation start point, the temperature increases. It reaches up to 520℃. Therefore, as shown in FIG. 6, the depth of the molten zone 1a' at this overheating point reaches approximately 300 mm, and the thickness of the fused zone 1a1 becomes uneven, as shown in FIG. 7(B). The surface roughness will also increase.

In this embodiment, a case is shown in which the irradiation intensity of the laser beam 2 is changed to control the irradiation, but the irradiation is not limited to this, and the irradiation may be controlled by changing the moving speed of the laser beam 2. As the irradiation of the laser beam 2 progresses, the temperature of the base material near the irradiation position increases.The moving speed of the laser beam 2 is increased by an amount commensurate with the detected temperature rise, so that the amount of heat of the aluminum alloy 1 at each irradiation position is equal to the total amount of irradiation. It is made to remain approximately constant throughout the stroke.

Further, as means for detecting the temperature near the irradiation position, in addition to using a contact type sensor such as the thermocouple 3 described above, it is also possible to use a non-contact type sensor.

The high-density energy hot wire used in this method is
Of course, in addition to the laser beam 2, an electron beam can also be applied.

〔Effect of the invention〕

As described above, the method for manufacturing a low-melting point metal member of the present invention involves irradiating the surface of a low-melting point metal member while moving high-density energy heat rays to locally melt and rapidly cool the metal structure to refine the metal structure. The high-density energy heat rays are applied so that the amount of heat of the metal member at the irradiation position of the high-density energy heat rays (the sum of the amount of heat directly given by the high-density energy heat rays and the amount of heat that has already been stored) remains approximately constant throughout the entire process of moving irradiation. It is for controlling. Therefore, the metal member does not overheat during the moving irradiation, and the resulting melted and quenched part has a substantially uniform thickness over the entire area, and the surface roughness is kept low, so the treatment is It can be performed well over a wide range. Furthermore, since the surface roughness is low, finishing of the product is easy and dimensional accuracy can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an outline of an embodiment of the present invention, and FIG. 2 is a sectional view showing the arrangement of thermocouples in the embodiment.
Figure 3 is an explanatory diagram showing the results of the example, Figure 4 (A)
(B) is a graph showing the surface roughness results according to the example, FIG. 5 is an explanatory diagram showing the surface roughness measurement direction, FIG. 6 is an explanatory diagram showing the results of the conventional example, and FIG. B) is a graph showing the results of surface roughness according to the conventional example. 1 is an aluminum alloy (low melting point metal member), 1a is a melting part, 2 is a laser beam (high-density energy hot ray), and 3 is a thermocouple. Figure 3 Figure 4 Traveling distance a Traveling distance a

Claims (1)

[Claims] 1. A method for manufacturing a low-melting point metal member in which the low-melting point metal member is irradiated with high-density energy hot rays, locally melted and rapidly cooled to refine the metal structure, in which the irradiation is performed while moving. A method for manufacturing a low-melting point metal member, characterized in that irradiation with high-density energy heat rays is controlled so that the amount of heat of the metal member near the irradiation position of the high-density energy heat rays is kept substantially uniform over the entire movement of the metal member. 2. The method of manufacturing a low melting point metal member according to claim 1, wherein the control of the irradiation of the high-density energy heat rays is performed by controlling the intensity of the heat rays. 3. The method of manufacturing a low-melting point metal member according to claim 1, wherein the control of the irradiation of the high-density heat rays involves controlling the moving speed of the heat rays.