JPS5897489A - Laser welding method - Google Patents

Abstract

PURPOSE:To execute spot welding extremely easily by opening an under hole to a material to be welded by the first irradiation of laser and welding the materials to be welded by the second irradiation. CONSTITUTION:The 1st irradiation generates energy by a laser 5 and works an under hole 6. The diameter of the under hole is 60-70% the spot welding diameter and arrives slightly at a material 2 to be welded. A part of a material 1 to be welded and the material 2 are melted simultaneously by the 2nd irradiation of the laser 5, whereby a sound molten metal 3 is obtained and the material 1 is thoroughly welded to the material 2. Since the laser 5 is irradiated to the metal 3 at the same center as that of the hole 6, a sufficient joined area is obtained without deviation to one side.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for spot welding relatively thin plates (1 to 3 cm) in overlap. Furthermore, this method can be used not only for overlapping spot welding of the same thin plates, but also for spot welding of steel or metal materials with different thicknesses.

Electron beam welding is used primarily for joining minute parts, but it has the disadvantage that welding cannot be performed in the atmosphere. Laser beams have recently been widely used to weld small parts in the atmosphere.

This method uses a light beam with a narrow wavelength range, so it can focus the light on a minute point, and therefore has a high energy density, making it suitable for minute welding. For processing minute parts, a fixed laser such as a YAG laser is suitable and has been put into practical use in view of ease of handling. However, as shown in Fig. 1, the YAG laser is effective if the material to be welded 1.2 is less than 1 degree, but if it exceeds l1101+, the melting of the material to be welded 2 will be small in the case of lap welding. Reliability regarding strength is poor. Therefore, in order to sufficiently melt 1.2 tl of the material to be welded, a method is adopted in which a pilot hole 4 is previously formed in the material to be welded 1 by some method, and then a laser is irradiated. When welding materials 1 and 2 to be welded one on top of the other, positioning the laser irradiation is important.If the center position is shifted, only the upper material 1 will melt and become uneven, as shown in Figure 2. As a result of melting, sound welding cannot be obtained. Therefore, it is necessary to perform the alignment work accurately.

The present invention provides a laser spot welding method for obtaining a sound welded part without the above-mentioned drawbacks.

The present invention relates to spot welding using a laser for one or more plate thicknesses, in which the first irradiation processes a prepared hole that reaches the material to be welded, the second irradiation irradiates a beam suitable for welding, The aim is to obtain a sound overlapping spot weld.

Examples of the present invention will be described below. FIG. 3 is an explanatory diagram for spot welding the bathed materials 1 and 2 by the method of the present invention. In the example, 5US3 with a plate thickness of 2 wn
04 lap welding was performed.

In the first irradiation, the laser 5 generates energy of about 35 J, and in order to obtain a predetermined spot welding diameter of 1 m,
A 0.6 cylinder with a pilot hole drilled is shown in Fig. 3(a).

The pilot hole 6 slightly reaches the material to be welded 2, and the laser 5 used is a pulsed Nd glass laser.

In Figure (a), if the diameter of the prepared hole is small compared to the predetermined spot diameter, the area of the joint between the welded materials 1 and 2 cannot be made large, and the areas that require strength will not have sufficient strength. I can't get it. On the other hand, if the pilot hole diameter becomes as large as the spot welding diameter, only the surface of the welded material 2 will be melted without melting the welded material 1 f-. The materials 2 cannot be joined sufficiently. Various fruits;
According to the inspection, if the diameter of this pilot hole is 60 to 70% of the spot welding diameter, one group of temporary welding material 1 and the material to be welded 2 will be melted at the same time. Got r
It became clear that the choreography of the welded material 1 and the welded material 2 was sufficiently performed.

Figure 3 (1) shows that the second irradiation was performed for welding, and the oscillation output was 35 J when the pilot hole was completely machined, and the focal position was adjusted to obtain the required welding spot diameter. shift it. In addition, the energy density was lowered to suit welding.

The weld metal 3 formed between the welded material 1 and the welded material 2 was not biased due to the laser 115 being irradiated in the same center as the processed hole, and a sufficient bonding area was obtained. Therefore, a highly reliable welding part was obtained.

The energy density can be adjusted by keeping the output the same and shifting the focus, by adjusting the output energy itself, or by installing an ND filter or mechanical aperture mechanism between the oscillator and the focusing lens. It is possible.

In this example, since it was necessary to obtain a predetermined spot diameter, a method of moving the focal point position was applied.

As explained above, according to the present invention, it is not necessary to align the prepared hole position and the irradiation beam, and spot welding can be performed extremely easily. Furthermore, since the irradiation is carried out along the same central axis, there is no welded part due to one-sided melting, and a highly reliable welded part can be obtained. Further, since drilling and welding can be performed with the same output value, there is no variation in output, and a stable weld can be obtained even when a large number of spot welds are performed.

[Brief explanation of the drawing]

Figure 1 shows the preparation of holes in the material to be welded for spot welding. FIG. 2 is a diagram illustrating the position of the prepared hole and the process of making contact. 1... Upper welded material, 2... Lower welded material, 3...
- Weld metal, 5... Laser light, 10... Preparation hole. Agent: Toshiyuki Usuda, Patent Attorney, Sudo A A J (OL) 475-

Claims (1)

[Claims] In laser spot welding, in which two or three sheets of steel or metal are overlapped and irradiated with a laser to perform spot welding, the first irradiation produces 60 to 70% of the final target spot weld diameter on the steel or metal. A laser spot welding method characterized by machining a pilot hole and performing predetermined bath welding in the second irradiation.