JPS59202194A - Micro-welding method - Google Patents

Abstract

PURPOSE:To prevent generation of residual stress owing to an abrupt temp. difference near the welding point in the stage of welding a micro-part by using a light beam by passing the light beam through a diaphragm mechanism having a specifically shaped diaphragm aperture. CONSTITUTION:A laser light beam 1 emitted from a light beam welding machine using a laser beam is restricted to laser light having the diameter D0 by a diaphragm mechanism 2 and is condensed by a condenser lens 3 to form a micro-spot image 5 of a diameter D1 on the surface of a work 4 thereby welding the work. A diaphragm aperture of the diameter d0 smaller than said diameter D0 is provided to the mechanism 2 or a brysanthemum-shaped notch 6a of the diameter d1 slightly larger than d0 is provided or a small hole group 6b of semitransparent part 2C is provided around the diaphragm aperture of the diameter d0. The temp. gradient in the part around the spot image 5 on the surface of the object to be welded is made gentle and the remaining of thermal stress owing to the abrupt temp. change is obviated, by which the generation of a crack and corrosion owing to the residual stress around the welding point is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION +al Technical Field of the Invention The present invention relates to a micro welding method for welding minute parts using a light beam, and particularly to a micro welding method that does not generate large residual stress in a welded part.

(bl Technology background) Many welding methods have been used since ancient times, such as electric resistance welding, arc welding, and gas welding using a gas burner, depending on the application. Moreover, electric resistance welding using a Suboso H8 welding machine has been used exclusively for high-precision welding.

Furthermore, light beam welding has recently been rapidly developed as a welding method for fine parts, and is particularly used for welding and assembling precise and fine mechanisms of information processing equipment.

(C1 Prior Art and Problems As is well known, laser beams and infrared rays can be optically converged and concentrated on a desired point, so the area of the welding point can be minutely controlled, and the energy density can therefore be increased. It has many advantages such as: 1) it does not cause any adverse effects such as temperature rise or oxidation on surrounding objects;

However, despite this high degree of energy concentration, there are also disadvantages based on this. Let me explain this point a little bit.

FIG. 1 is a diagram illustrating an optical system of a light beam welding machine using a laser beam. A laser beam 1 emitted from a laser light source (not shown) is generally projected in parallel lines with a diameter of 3 to 10 mm, and the laser beam at the periphery is removed by an aperture mechanism 2 with an inner diameter Do. After that, the light is condensed by the condensing lens 3 located at the point R and focused at the focal point F, and then conversely diverges to reach the diameter spot 7 on the surface of the workpiece 4 located at the point W. Tie statue 5.

In the figure, f indicates the focal length as the distance between R and F, and d
represents the distance between F and W and is one divergence distance.

FIG. 2 is a diagram showing the energy intensity distribution of the light beam 1 of the diameter from the light source of FIG. 1, as shown in FIG.

The energy distribution generally has a Gaussian distribution.

Now, as a result of removing the peripheral portion of the one-dimensional light beam 1 using the aperture mechanism 2, a sharp distribution is obtained as shown by the hatched area with vertical lines in FIG. This laser beam is passed through lens 3.
A spot image 5 is formed on the surface of the workpiece 4 by converging the beam and projecting it onto the workpiece 4, and the workpiece 1 of the spot image 5 is melted and welded.

In such cases, although the diameter of the welding point can be made quite small, such as 0.2 to 0.3 mm, the energy distribution in and around the spot image 5 is too steep and the welding point on the workpiece 4 is As a result of forming a sharp temperature distribution, the workpiece 4
The difference in expansion within the material of the object becomes enormous.

So-called thermal stress remains. This stress can cause cracks to occur in or around the welding point, and if the welding point happens to come into contact with chemicals, the residual stress can cause various problems such as abnormal corrosion. Sometimes. To make matters worse, the above-mentioned fractures due to residual stress often occur not immediately after welding but after a certain period of time has passed, making it difficult to eliminate in the inspection process and causing major problems in the reliability of micro welding. countermeasures are urgently needed in all areas.

(dl) Purpose of the Invention The present invention has been made in view of the above-mentioned points, and it is an object to provide a welding method that reduces the occurrence of cracks, etc. in the vicinity of the welding point during micro welding.

fe) Structure of the Invention The object of the above invention is to provide micro welding in which a light beam is converged by an optical system composed of a lens system and an aperture mechanism, the light beam is concentrated on a minute point, and an object is welded using the energy of the light beam. This is easily achieved by using an aperture mechanism that has a periphery of the aperture that partially transmits the light beam.

+f) Embodiments of the Invention Below, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a plan view showing an embodiment of an aperture mechanism of an optical system according to the present invention in microwelding using a laser beam.

The diameter of the conventional aperture hole of the aperture mechanism 2 shown in FIG. 1 is Do, and as shown in FIG.
A chrysanthemum-shaped cutout as shown in the figure forms a portion 6a.

In that case, the energy distribution of the laser beam within the diameter d1 would be as shown by the curve a in FIG.
Part of the energy of the laser beam between the two is blocked. Therefore, the energy distribution of the laser beam at the spot image 5 on the surface of the workpiece 4 produced by the aperture mechanism 2a shown in FIG. 4 (al) is the distribution hatched by the vertical lines in FIG. In addition, the energy distribution around the spot image 5 (portion A in the figure) is considerably relaxed, so the temperature distribution around the welding point becomes gentler than in the conventional case.
Residual stress, which has been a problem in the past, can be reduced.

As mentioned above, it is good to provide a region on the peripheral edge of the diaphragm mechanism 2 that partially blocks the laser beam, so a region such as the diaphragm mechanism 2b shown in FIG. Another embodiment of the micro welding method according to the present invention is one having a group of small holes 6b on the periphery of the opening. Further, as shown in FIG. 3 (C1), a translucent material such as a half mirror The aperture mechanism 20 formed by the above is also an embodiment of the present invention.

Incidentally, since the aperture mechanism 2 described above is exposed to the laser beam when the laser beam is not yet converged, there is no particular problem that the temperature thereof increases.

Usually punching or etching from a thin metal sheet such as copper.

Alternatively, it is manufactured by a method such as laser processing.

(gl Effects of the Invention As is clear from the above explanation, the micro welding method based on the present invention has problems such as cracks occurring near the welding point and small holes remaining due to poor weld build-up. It is possible to solve this problem and improve the reliability of the micro welding method.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the optical system of the micro welding method using a laser beam, Figure 2 is an energy distribution diagram within the laser beam from the light source, and Figure 3 is the light beam used in the micro welding method shown in Figure 1. FIG. 4 is a plan view showing various embodiments of the aperture mechanism of the optical system of the micro welding method based on the present invention; FIG. 5 is a diagram showing the energy distribution in the spot image of the welding point. It is a line diagram showing distribution. In the figure, 1 is a laser beam and 2 is an aperture mechanism. 3 is a lens, 4 is a workpiece, 5 is a spot image, and 6 is an embodiment of the periphery of the aperture mechanism according to the present invention. Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] An optical system comprising a lens system and an aperture mechanism converges a light beam and concentrates the light beam on a minute point. 1. A micro welding method for welding objects using the energy, characterized in that the micro welding method uses a diaphragm mechanism that forms a periphery of a diaphragm hole that partially transmits the light beam.