JPH03138091A - Laser beam welding method - Google Patents

Abstract

PURPOSE:To perform machining with high efficiency in CO2 laser beam welding of ferrous materials by performing machining in the groove form on materials to be welded and considering an angle of incidence and irradiation efficiency of a laser beam. CONSTITUTION:In butt welding of the materials 3 to be welded, 80 deg. angle V groove with respect to a horizontal plane is formed on the end faces of the materials 3 to be welded and the linear polarized laser beam 1 is condensed on this V groove face by a condenser lens 2 and a V groove part is irradiated with the laser beam 1 to form a welding penetration part 4. At this time, efficiency is improved by absorptivity with respect to the ferrous materials to irradiate a P polarization component having an electric vector parallel to the groove face with a linear polarization component of a CO2 laser beam by inclining the V groove by a slant angle theta=70-85 deg. (angle of polarization). By this method, welding with high efficiency is made possible and welding at high speed with low electric power can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a laser welding method using a carbon dioxide laser.

[Prior art] Conventionally, in welding methods that use laser light, the wavelength of the carbon dioxide laser light has a large reflection on iron-based materials, which reduces the conversion efficiency of converting the light energy of the laser light into thermal energy on the workpiece. It's bad. Therefore, for example, the plate thickness t-
When doing 1mm overlap welding, increase the laser power to 1mm.
．． It was necessary to increase the output to 5kW or more. Alternatively, the crabbing speed must be extremely slow.

[Problems to be solved by the invention] However, the cost of laser oscillators is high due to the fact that the device has not yet been mass-produced and each part is a precision component, and the laser oscillation efficiency is only 20%.
Low as below. Therefore, effectively absorbing the output laser light into the workpiece has been one of the challenges in replacing the conventional welding method with laser welding.

The present invention has been made to solve the above-mentioned problems, and is a welding method using a laser beam.
By welding at a low output and maintaining the same welding speed as before, the rated output of the laser oscillator installed can be kept low, and the electricity cost used for glow discharge to perform laser oscillation can be reduced in the running cost during processing. The purpose of this invention is to provide a laser welding method that can reduce the cost of welding processing.

[Means for Solving the Problems] To achieve this object, the method of the present invention uses a linearly polarized beam in a laser beam, and in order to improve its beam absorption characteristics, a V-shaped groove or a modification thereof is used. The shape is processed and welded.

[Function] The present invention having the above-mentioned configuration processes a V-shaped groove or an improved shape thereof on a workpiece to be welded, and adjusts the slope angle to θ-
By being tilted at 70 to 85 degrees (Bliny star angle), the efficiency is at right angles due to the absorption characteristics of iron-based materials that irradiate the linearly polarized component of the carbon dioxide laser beam with the P-polarized component that has an electric vector parallel to the entire surface. The efficiency is dramatically higher at 30-80% compared to 10% in directional irradiation, and welding can be performed with high efficiency.

[Example 1] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

First, a laser welding method according to an embodiment of the present invention will be described with reference to FIG. This welding is a seam welding,
The end faces of the objects to be welded 3 are processed at an angle of 80° with respect to the horizontal plane, the objects to be welded 3 are spliced together, and a V-shaped groove is formed at the welding position. A laser beam 1 having linearly polarized light is focused on the V-groove 9 surface by a condensing lens 2, and an appropriate day focus value is set, and the V-groove is irradiated to form a welding penetration part 4 and to cover the surface. This is for welding the workpiece 3. Figure 5 is P
This shows the incidence angle and absorption rate of carbon dioxide laser of iron, which is zero in polarized light, and is approximately 50% at an 80° angle (Bliny star angle).
It can be seen that the absorption rate of FIG. 2 shows the resonator configuration of a laser oscillator that outputs linearly polarized light. In the figure (
In a), it is composed of an output mirror 5, a folding mirror VT6, and a total reflection mirror 7, and the direction of vibration of light is perpendicular to the plane of the paper. (
b) is also similar to (a). For (C), the laser oscillation medium is contained in a container with Brewster's angle at both ends, and an output mirror 5 and a total reflection mirror 6 are placed outside of the container.
The vibration direction of the light is linearly polarized light parallel to the plane of the paper. FIG. 3 shows examples of groove shapes other than V-shaped grooves that can improve absorption characteristics. In both cases, the groove shape is such that θ is approximately 70 to 85 degrees. FIG. 4 shows another example of a welded shape to which this welding method can be applied.

(a) is lap welding, (b) is seam welding, (c
) is a fillet weld. 4 indicates a welding penetration part.

Figure 6 shows the state in which welding is actually performed.

The laser processing machine is composed of an oscillator 10, a power supply 8, and a processing table 9. Inside the oscillator 1o, there is a laser resonator composed of a total reflection mirror 7, a folding mirror 6, and an output mirror 5. A laser beam is output. This resonator is of the same type as that shown in FIG. 2(a), and the output laser beam is a linearly polarized light wave having an electric vector in the direction C in FIG. 6. The laser beam vertically bent by the external folding mirror 6 has an electric vector in the C direction. And processing table 9
The object 3 to be welded is irradiated with light. The workpiece to be welded 3 has a V-groove machined with a surface inclined at 80 degrees Celsius with respect to the horizontal plane, and a processing table 9 is set in order to perform welding using the incident angle of the maximum part of the P-polarized wave absorption characteristic shown in Fig. 5. Move in the Y direction and weld.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, in carbon dioxide laser welding of iron-based materials, efficiency is increased by taking into account the incident angle of the laser beam and its irradiation efficiency. This allows extremely highly efficient processing. Therefore, high speed processing is possible with low power consumption. Therefore, this method has the effect of providing a welded product at low cost.

[Brief explanation of the drawing]

1 to 6 show embodiments embodying the present invention. FIG. 1 is a schematic diagram of seam welding as an example of the laser welding method of this embodiment, and FIG. 2 is a diagram showing an outline of seam welding. Figure 3 is a diagram showing an example of a laser oscillator that outputs linearly polarized light, Figure 3 is a diagram showing an example of a groove other than the V-shaped groove to increase absorption of laser light, and Figure 4 is a diagram to which the present invention can be applied. FIG. 5 is a diagram showing the incident angle and absorption rate of the linearly polarized component of the carbon dioxide laser beam on the P wave of the iron-based material, and FIG. 6 is a diagram showing the welding state. In the figure, 1 is a laser beam, and 3 is an object to be welded. Patent Applicant Brother Industries, Ltd. President Yoshihiro Yasui Figure 1 Figure 2 (a) (b) Figure 3 (a) (b) (C) Figure 5 Hitotouheji C) @ Figure 4 (a) (1)) (c) 1N6 diagram

Claims (1)

[Claims] 1. In a laser welding method using a carbon dioxide laser for ferrous materials, the angle of incidence on the ferrous material of a P-polarized component having an electric vector parallel to the plane of incidence on the workpiece should be approximately the same as the Brewster angle. , a laser welding method characterized by processing a groove shape on a workpiece and then welding the workpiece.