JPH04138889A - Head device for laser beam machining - Google Patents

Abstract

PURPOSE:To obtain adaptability for an object to be processed by bending one of the laser beam systems halved by a partial reflection mirror with a total reflection mirror and providing a lens for a normal working laser beam and an auxiliary working laser beam. CONSTITUTION:The laser beam from a laser beam oscillator 1 is halved by a partial reflection mirror Ms into a 1st laser beam system abundant in beam energy and a 2nd laser beam system poor in it, either is bent by a total reflection mirror Mm, a lens is provided at least in one system, the 1st beam system is used for a normal working and the 2nd beam system is for the auxiliary working. In this way, the laser beam energy corresponding to the object to be processed can be used. When this is applied to welding a surface treated steel sheet having a rust preventive film, it is used effectively to prevent welding defects from generation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a head for laser processing, and particularly to a head for laser processing that contains zinc or a zinc-containing alloy, such as a galvanized steel plate, a zinc primer-coated steel plate, or a galvanized aluminum plate. The present invention relates to a laser processing head suitable for welding surface-treated metal plates having a rust-preventing film on the surface and other surface-treated metal plates.

(Conventional technology and problems to be solved) In recent years, in the automobile and housing industries, galvanized steel sheets, galvanized steel sheets, The use of surface-treated steel sheets with improved rust prevention properties, such as zinc primer-coated steel sheets, is rapidly expanding.

Although this kind of surface-treated steel sheet has excellent rust prevention properties, compared to ordinary steel sheet without surface treatment,
Welding defects such as pits and spatters are likely to occur, and weldability is extremely poor. Therefore, at present, we mainly use experience in low-speed welding (approximately 30c+e/min) and welding with gaps between steel plates (gap of approximately 0.5-I) using coated arc welding rods or solid wires with adjusted compositions. We have responded by making improvements in terms of construction based on the following.

However, these welding methods have the fatal problem of not being able to completely prevent the occurrence of welding defects because they are performed without removing in advance the rust-preventive coating that causes welding defects. Furthermore, efficiency is low due to the slow welding speed, and defects such as burn-through and undercuts are likely to occur due to gaps between the steel plates.

On the other hand, it has been pointed out that an increase in welding speed and a decrease in the gap between steel plates will lead to an increase in blowholes and the amount of spatter due to the presence of zinc and its compounds in the anti-rust coating.

However, it is possible to manually remove the anti-rust film before welding, but this is clearly inefficient, and a method of removing the anti-rust film by TIG welding in advance has also been attempted. However, there are problems in that it is difficult to control the width to be removed, and unnecessary parts are burned, and the large amount of heat input causes angular deformation of the steel plate.

Moreover, such a problem similarly occurs in a surface-treated aluminum plate whose surface is coated with zinc or a zinc alloy.

Incidentally, a welding method using a laser beam as a welding heat source is known. This method uses one laser beam head to concentrate energy and perform welding. However, in terms of weldability and weld defects, it is almost the same as the conventional method using coated arc welding rods or solid wire, and furthermore, the hardness of the weld becomes higher than necessary due to rapid heating and cooling, and the steel type In some cases, it may create an extreme imbalance with the base metal, and even if this does not occur, it can only be used for ultra-low carbon steel, which limits the types of steel it can be applied to.

Therefore, the present inventor has previously developed the use of a laser beam for welding such surface-treated steel sheets. In this method, prior to main welding, welding using a laser beam is performed to evaporate and remove the rust preventive coating. However, in this method, it is possible to use a laser beam for the main welding, but when using it for the main welding, as mentioned above, in particular, the hardness of the welded part should not be made higher than necessary.-1 Laser processing with various functions It is necessary to develop a head device.

The present invention was made in response to the above request, and it is possible to obtain a sound welded part of various surface-treated metal plates without causing welding defects, and to reduce the hardness of the base metal and the hardness of the welded part. The object of the present invention is to provide a laser beam processing head that can appropriately adjust the welding speed and perform highly efficient welding.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventor has made the present invention as a result of extensive research into the beam system of a laser beam generated from a laser beam oscillator.

That is, the laser processing head according to the present invention uses a partial area reflection mirror or a partial reflection mirror to separate the laser beam generated from one laser oscillator into a laser beam (first beam system) with high beam energy and a laser beam with high beam energy (first beam system). Divide into two parts with a smaller laser beam (second beam system),
In addition, either the first beam or the second beam is bent by a total reflection mirror, and at least one of the first beam system and the second beam system is provided with a lens, and the first beam system is used for main processing. The present invention is characterized in that the second beam system is configured to be used for auxiliary processing.

The term "partial area reflective mirror" used here refers to a mirror that controls energy by completely coating a portion of the mirror and allowing laser light to pass through the remaining portion, as shown in Figure 4 below. In other words, a "partially reflective mirror" refers to a mirror whose entire mirror is coated using a method such as dielectric coating to control the amount of energy transmitted.

The present invention will be explained in more detail below.

(Example) FIG. 1 shows an example of a laser beam system in a laser beam processing head of the present invention.

In FIG. 1, a laser beam generated from one laser beam oscillator 1 is first divided into two by a partial area reflection mirror or a partial reflection mirror Ms to form a first beam with more energy and a second beam with less energy. ,Also,
The first beam system includes a total reflection mirror (e.g., parabolic mirror) MIm
The beam path is bent to direct the beam in the same direction as the second beam, and a lens (condensing lens) Ls (or Lm) is provided in one or both of the first beam system and the second beam system. It is the composition.

As an example of the partial area reflection mirror Ms, as shown in Fig. 2, mirrors with mirror parts of various shapes (shaded areas in the figure) are used to reflect the first beam with various energies. For example, in the case of (,), a part of the circular mirror is arranged in the center, and in the case of (b), a part of the ring-shaped mirror is arranged around the periphery. A first beam is formed by the beam, and the beam energy ratio of the first beam and the second beam can be changed depending on the area of a part of the mirror. On the other hand, in the case of (c), a semicircular mirror is movably provided, and by moving this mirror, the beam energy ratio between the first beam and the second beam can be arbitrarily changed.

When a partial area reflection mirror having the shape shown in FIG. 2 is used, the laser beam generated from the laser beam oscillator can be divided into two as shown in FIG. In the case of (a), the central part is reflected as the first beam, in the case of (b), the peripheral part is reflected as the first beam, and in the case of (c), the right or left part is reflected as the first beam. It is. In these aspects, the laser beam is considered to be a collection of beams having many modes, and the energy distribution in the cross section of the laser beam is not necessarily uniform, but partial area reflection having mirror portions of various shapes as described above is possible. By using mirrors, the beam energy can be divided into desired beam energies.

According to the laser processing head of the present invention, the following functions can be realized.

First, the laser beam energy generated from the laser beam oscillator can be divided into two laser beams with arbitrary energy ratios. In this case, the beam energy ratio between the main processing beam and the auxiliary processing beam is such that the energy of the auxiliary processing beam is within 50% of the total.

Therefore, since the beam energy can be divided into two ways, strong and weak, it can be used for auxiliary processing in welding various surface-treated plates, such as surface-treated steel plates or aluminum plates, which have anti-rust coatings containing zinc or zinc alloys on their surfaces. The beam can be used to remove the anticorrosive coating beforehand, or can also be used for preheating treatment or for postheating treatment. On the other hand, a single processing beam can be used for processing such as actual welding. At this time, the beam energy ratio between the main processing beam and the auxiliary processing beam is approximately 4:1.

Second, one or both of the first beam and the second beam can be scanned.

Scanning refers to vibrating a mirror to oscillate the beam in a direction perpendicular to the welding direction, as illustrated in Figures 4(a) to (c).It is easy to vibrate a total reflection mirror. Therefore, for example, the total reflection mirror of the first beam can be vibrated.Of course, it is also possible to fix the distance between the main processing beam system and the auxiliary processing beam and then scan the entire laser beam system. .

Third, since the laser beam system is equipped with a lens, the distance between the workpiece and the focal point can be varied to create a so-called defocus (focal point), as shown in Figures 5(a) and (b). The closer the focal point is to the workpiece, the narrower the irradiation range can be.

The irradiation width, area, and beam energy per unit area can be controlled by the degree of day focus.

Therefore, high power beam energy (e.g. 10KW
) Even if a laser beam is used, it is possible to easily perform processing that suits the purpose by defocusing the laser beam according to the purpose of processing. For example, when using an auxiliary processing beam to remove a rust preventive film, by defocusing it, only a predetermined width of the rust preventive film on the weld line can be efficiently evaporated and removed, and the main processing beam can be defocused. If irradiated without focusing, the beam with the highest energy density can be used for main processing.

Of course, it goes without saying that it can be used with various laser beams.

For example, the type of laser light is gas laser (e.g. C
Various lasers such as O2 laser), solid state laser (e.g. YAG laser), etc. are possible, but CO2 which can obtain high output
A laser or a YAG laser, which is easy to handle because its energy passes through an optical fiber, is suitable.

Since the laser has excellent light focusing characteristics, the workpiece is not heated more than necessary, and deformation of the workpiece due to thermal stress or the like can be ignored.

If necessary, it is also possible to feed a filler wire directly under the main processing beam for welding.

(Effects of the Invention) As described in detail above, according to the present invention, the laser beam generated from the laser beam oscillator is divided into two, and a lens is provided in at least one beam system, so that the main processing beam and the auxiliary processing beam can be separated from each other. Since a special beam is formed, any beam energy depending on the processing purpose can be used for processing. Furthermore, processing to a predetermined width is easy by scanning or defocusing the beam. In particular, it can be applied to welding surface-treated steel sheets with anti-rust coatings containing zinc or zinc-containing alloys on the surface, such as galvanized steel sheets and zinc primer-coated steel sheets, or various surface-treated sheets such as steel materials or aluminum sheets. Since the anti-rust coating can be removed first using the auxiliary processing beam and then the main welding can be performed, it is possible to prevent welding defects such as bits and blowholes from occurring.

The auxiliary processing beam can also be used for preheating or post-heat treatment.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a laser beam system according to the present invention, and FIGS. 2(a) to (c) are diagrams explaining various shapes of the mirror portion of a partial area reflection mirror. FIGS. 3(a) to 3(c) are diagrams illustrating a mode in which the energy distribution of a laser beam is divided into two using a partial area reflection mirror. FIGS. 4(a) to 4(c) are diagrams for explaining the scanning mode, and FIGS. 5(a) and (b) are diagrams for explaining the defocusing mode. 1... Laser beam oscillator, 2... Processed part, Ms
...Partial area reflection mirror, M shoes...Full area reflection mirror Ls, L seal...Lens. Patent issuer Hisashi Nakamura, Patent attorney representing Kobe Steel, Ltd. Figure (a) Figure 2 (b) (C) (Q) Figure 3 (b) (C) Figure (Q) (b) (C) 庺VhaQτp is ＼ Engraving of the drawing (no changes in content) Figure (b) ,′,＞, . 1 1 aH+y@N Procedural Amendment November 8, 1990 1. Case description Relationship to 1990 Patent Application No. 262245 case

Claims (4)

[Claims] (1) A laser beam generated from one laser oscillator is divided into a laser beam with high beam energy (first beam system) and a laser beam with low beam energy (second beam system) using a partial area reflection mirror or a partial reflection mirror.
dividing the beam into two, bending either the first beam or the second beam with a total reflection mirror, and providing a lens in at least one of the first beam system and the second beam system,
A laser processing head characterized in that the first beam system is used for main processing and the second beam system is used for auxiliary processing. (2) The beam energy of the auxiliary processing beam is 5
The laser processing head according to claim 1, wherein the laser processing head is within 0%. (3) The laser processing head according to claim 1, wherein the laser beam system is provided with a scanning mechanism. (4) The laser processing head according to claim 1, wherein the laser processing head is defocused by a lens.