JPH04157085A - Laser beam welding equipment - Google Patents

Abstract

PURPOSE:To simplify the structure of an optical system, facilitate the work and improve the accuracy by photodetecting and observing an evaporation flame by a photosensor having an optical diode group and focusing and aligning a laser beam. CONSTITUTION:When a material 102 to be welded is mounted on a material 101 to be welded and the materials 101 and 102 to be welded are subjected to fillet welding, the apex formed between the horizontal surface of the material 101 to be welded and the vertical surface of the material 102 to be welded is irradiated with the laser beam P from the direction of an angle of 45 degrees and welding traces are provided on the apex part. When the focus of the laser beam P is coincident with the apex, the direction of the evaporation flame F is coincident with a proceeding path of the laser beam P and the height of the evaporation flame F becomes maximum and this state is most quality is most excellent. When the focus is greatly deviated from the apex, the evaporation flame F stands upright with respect to the horizontal surface. In such a case, fillet welding is not performed.

Description

[Detailed Description of the Invention] [Summary] Regarding a laser welding device, an object of the present invention is to provide a laser welding device that is inexpensive, easy to focus and align the focus with a welding point, and has excellent welding quality. For the purpose of It has a group of photodiodes whose light-receiving surface is divided into four equal parts by a pair of parallel elements placed parallel to the laser beam and a pair of vertical elements placed perpendicular to the laser beam. an optical sensor set directly horizontally to the generated evaporative flame, a operational amplifier inputting the output of the parallel arrangement element, another operational amplifier inputting the output of the vertical arrangement element, and the output of both operational amplifiers. The configuration consists of a detection unit each equipped with a display.

[Industrial application field]

The present invention relates to a laser welding device.

Laser welding methods that use YAG, etc. as a laser light source have the characteristics of being able to weld the object to be welded without contact, being able to perform precise micro-processing, and having almost no mechanical or thermal distortion. Widely used for welding of optical equipment parts, etc.

[Conventional technology]

FIG. 4 is a block diagram of a conventional laser welding device, FIG. 5 is a block diagram of another conventional example, and FIG. 6 is a block diagram of still another conventional example.

In FIG. 4, the path of laser light P emitted from a laser light source 1 such as YAG is shifted by 90 degrees by a mirror 2 and irradiated onto a condensing lens 3. The laser beam P is focused on the joint between the weld and the workpiece 1°2.

By converging the laser beam P on the focal point of the condenser lens 3 in this way, the workpiece to be welded in both waves is heated, and as a result, the material of the workpiece is melted and evaporated, and the welding process is performed.

Note that in the case of seam welding, the welding apparatus itself may be moved parallel to the welding line, but when welding small parts, it is common to move the workpiece to be welded parallel.

On the other hand, the quality of welding depends on narrowing down the laser beam P to a predetermined welding point, that is, making the focus of the condenser lens 3 coincide with the predetermined welding point.

However, since the laser beam P is an invisible beam, it is not possible to visually align the convergence position of the laser beam P (that is, the focal point of the condensing lens 3) and the welding point.

Therefore, the illumination lamp 16 is installed in a housing housing the laser light source 1, and the visible light (hereinafter referred to as guide light) emitted from the illumination lamp I6 is input into the condenser lens 3 that converges the laser light P, and the guide light is welded. It converges on a point.

More specifically, a dichroic mirror 4 that transmits the laser beam P and reflects the guide light is installed between the mirror 2 and the condensing lens 3 at an angle of 45 degrees with respect to the optical path. Then, the beam of guide light from the illumination lamp 16 is passed through a half mirror.
Dichroic mirror 4 by shifting 90 degrees by 17
The guide light is reflected by the dichroic mirror 4, and then introduced into the condenser lens 3, so that the optical path coincides with that of the laser light P, and the guide light is converged at the welding point.

On the other hand, a TV left camera 5 is mounted on the optical axis of the half mirror 17 on the opposite side of the dichroic mirror 4 to photograph the object to be welded.

The video monitor 19 connected to the TV camera 5 determines where on the object to be welded the guide light converges.
The beam diameter of the guide light on the workpiece is also observed.

While observing on the video monitor 19 in this way, the laser beam P is focused by focusing the TV left camera 5 (an operation to move and adjust the entire welding device), and the entire device is moved to focus on the welding point. Aligning with the focal point.

The device shown in FIG. 5 is obtained by separating the device shown in FIG. 4 into a laser light source section 10 and a condensing section 20B, and connecting the laser light source section 10 and the condensing section 20B with an optical fiber 9.

Therefore, the laser light source section 10 is provided with a condensing lens 8 for transmitting light to the optical fiber 9 without providing a mirror, and the condensing section 20B is provided with a lens for converting the light emitted from the optical fiber 9 into a parallel beam. 8B is provided.

The arrangement shown in FIG. 5 has an advantage over the arrangement shown in FIG. 4 in that only the condensing section 20B needs to be moved and adjusted during focusing and the like.

The laser welding device shown in FIG. 6 has a laser light source section 10B and a condensing section 20 connected by an optical fiber 9.

The laser light source unit 10 is equipped with a guide light laser 30 in addition to the laser light source 1, and the guide light emitted by the guide light laser 30 passes through two mirrors 31 and 32 to the optical path of the laser light P emitted by the laser light source 1. I'm trying to make them overlap.

On the other hand, the condensing unit 20 includes a ferrule 21 attached to the output terminal of the optical fiber 9, and a condensing lens 3 attached to the ferrule 21.
It is equipped with.

Then, the distance between the condensing section 20 and the objects to be welded 101 and 102 is adjusted so that the guide light is most focused, and the projection point of the guide light on the object to be welded is aligned with the welding point.

[Problem to be solved by the invention]

By the way, the laser welding apparatus shown in FIGS. 4 and 5 has a complicated optical system and a TV camera, etc. is installed in the light condensing section, so it is expensive. Since the device (including the light condensing part) is large, it is difficult to focus and align the focus and the welding point.

In addition, in the case shown in Fig. 6, there is an error (the error is around 10) between the focus of the guide light and the focus of the laser light due to the difference in wavelength between the guide light and the laser light. It is difficult to confirm the focal point position due to the small beam diameter of the guide light on the surface of the welding object. Both of these problems caused the problem of poor welding quality.

The present invention was created in view of these points, and provides a laser welding device that is inexpensive, easy to focus and align the focus with the welding point, and has excellent welding quality. It is intended to.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a laser light source unit 10 that includes a laser light source l for transmitting a laser light P to an optical fiber 9, and a A condensing section 20 is installed to focus the laser beam P on the welding point.

In addition, in order to receive the light of the evaporative flame F generated at the welding point,
A pair of parallel elements 55-1.55-3 arranged parallel to the laser beam and a pair of vertical elements 55-2.55-4 arranged perpendicular to the laser beam form a light-receiving surface of 4. Optical sensor 5 with equally divided photodiode group 55
0, and the optical sensor 5o is set so that the optical axis and the welding line are parallel to each other within a plane including the traveling path of the laser beam P and the welding point.

And parallel arrangement element 55-1.55- of optical sensor 50
3 and a vertically arranged element 5.
5-2.55-4, and a detector 65 that displays the outputs of both the operational amplifiers 61 and 62, respectively.

[Effect]

In laser welding, the height of the evaporated flame is highest when the beam diameter of the laser beam is narrowed down to the minimum on the surface of the workpiece.

Therefore, the pair of diode elements of the photodiode group 55 arranged parallel to the laser beam (that is, the parallel arrangement elements 55-
By adjusting and moving the condensing unit 20 so that the output voltage of the operational amplifier 62 connected to 1.55-3) becomes almost zero,
The focus of the laser beam can be made to match the surface of the workpiece.

In addition, within a plane including the traveling path of the laser beam P and the welding point,
Install the optical sensor 50 so that the optical axis and welding line are parallel to each other.
is set.

Therefore, the pair of diode elements of the photodiode group 55 arranged perpendicularly to the laser beam (that is, the vertically arranged elements 55-
2.55-4) By adjusting and moving the condensing unit 20 so that the output voltage of the operational amplifier 61 connected to the output voltage becomes almost zero,
The laser beam projection position can be aligned.

On the other hand, the condensing unit 20 is composed of a ferrule 21 attached to the end of the optical fiber 9 and a condensing lens 3 attached to the output end of the ferrule 21, so it is small and lightweight and easy to handle. is easy.

Further, the laser light source section 10 has a simple structure in which only the laser light source 1 is installed.

Therefore, the laser welding device of the present invention is inexpensive, easy to focus and align the focus with the welding point, and has excellent welding quality.

〔Example〕

The present invention will be specifically described below with reference to the drawings. Note that the same reference numerals refer to the same objects throughout the plan.

FIG. 1 is a block diagram of the present invention, in which (a) shows a laser light source section;
A diagram showing the configuration of a light condensing section and an optical sensor, and (b) is a connection diagram between the optical sensor and a detection section.

(a), (b), (C), (d), (
Figures 3(a), 3(e) and 3(e) are diagrams of an evaporative flame during fillet welding, and Figures 3(a), 3(b), 3(c), and 3(d) are diagrams explaining the present invention in detail.

In FIG. 1, a laser light source unit 10 is provided with a condensing lens 8 for transmitting a laser beam P emitted from the laser light source 1 to an optical fiber 9.

The condensing unit 20 includes a ferrule 2 at the output terminal of the optical fiber 9.
1 and a condenser lens 3 is mounted on this ferrule 21.

The optical sensor 50 has an objective lens 52 attached to the tip of a cylindrical detection head 51, and a photodiode group 55 inserted behind the objective lens 52 so that the axis of the detection head 51 and the optical axis coincide. It is.

The photodiode group 55 includes photodiode elements each having a quarter disk shape when viewed from the front (parallel arrangement element 55-1. vertical arrangement element 55-2. parallel arrangement element 55-3. vertical arrangement element 5).
5-4) are combined and inserted into a cylinder 53 in a cylindrical shape, and by inserting the cylinder 53 into the hollow part of the detection head 51, the optical axis of each photodiode element is aligned with the detection head 5.
It is aligned with the optical axis of No. 1.

Such an optical sensor 50 is configured to perform seam welding between the optical axis and the welding line (the workpiece 101 and the workpiece 102 It is set near the object to be welded so that the two parts (part) are parallel to each other, and receives the light of the vaporized flame F generated at the welding point.

On the other hand, the detection section 60 includes two operational amplifiers 61 and 62, and a display 65 that displays the outputs of both operational amplifiers 81 and 62, respectively.

As shown in FIG. 1(b), the operational amplifier 62 includes a pair of parallel elements 5 disposed within the detection head 5 so as to be parallel to the traveling path of the laser beam P when viewed from the front.
It is connected so that the output of 5-1.55-3 is input.

Further, the outputs of a pair of vertically arranged elements 55-2 and 55-4 arranged in the detection head 51 are input to the operational amplifier 61 so as to be perpendicular to the traveling path of the laser beam P when viewed from the front. It is connected.

Next, with reference to FIGS. 2 and 3, the present invention will be described in detail using fillet welding as an example.

In laser welding, when the beam diameter of the laser beam is narrowed down to the minimum on the surface of the workpiece, the height of the evaporator flame F generated by melting and vaporizing the workpiece is the highest.

As shown in FIG. 2(a), when the workpiece 102 is placed on top of the workpiece 101 and the workpieces 101 and 102 are fillet welded, the horizontal surface of the workpiece 101 is Laser light P is irradiated from a 45 degree direction to the apex formed by 101P and the vertical surface 102V of the workpiece 102 to create a diameter at the apex. Welding marks are provided.

Now, if it matches the focus or apex of the laser beam P, the second
As shown in Figure (b), the direction of the evaporator flame F coincides with the traveling path of the laser beam P (at an angle of 45 degrees), and the height of the evaporator flame F is the highest.

This condition is the most desirable and provides the best welding quality.

Then, as shown in FIG. 2(C), the focal point becomes thick and upright at the apex. In such cases, fillet welding is not performed.

In addition, as shown in FIG. 2(d), L2 (L
When the position 2<LO> is reached, welding between the workpiece 101 and the workpiece 102 is performed, but in that case, the vaporized flame F is
Between the vertical plane 102 and the traveling path of the laser beam P, the focus of the laser beam P moves away from the apex as shown in FIG. ■
When the side reaches the position L2 (L3<Lo), welding between the workpiece 101 and the workpiece 102 is performed. In that case, the evaporative herdsman F uses the laser beam between the horizontal plane 101P and the path of the laser beam P. It tilts in a direction approaching the traveling path of the light P.

Then, as shown in Figure 2), when the focal point or apex is greatly shifted and the evaporative herdsman F reaches the position L4 (L4 >Lo) on the vertical plane 102■, the evaporative herdsman F stands upright with respect to the vertical plane 102■. Note that fillet welding is not performed in such cases.

Since the evaporative herdsman F has the above-mentioned properties, when the evaporated herdsman F is observed using the optical sensor 50 and the detection unit 60 according to the present invention, if the focus of the laser beam P coincides with the apex of the object to be welded, As shown in FIG. 3(a), the evaporation herdsman F is the highest and its direction coincides with the traveling path of the laser beam P.

Therefore, the parallel arrangement element 55-1 and the parallel arrangement element 55
-3 is the highest and the same amount of light is received. Therefore, the output of the operational amplifier 62 connected to these becomes zero.

Further, in this case, the amounts of light received by the vertically arranged element 55-2 and the vertically arranged element 55-4 are equal at most. Therefore, the output of the operational amplifier 61 connected to these becomes zero.

If the focal point does not coincide with the apex of the workpiece, as shown in FIG. 3Tb), the evaporating herdsman F is small and its direction coincides with the traveling path of the laser beam P.

Therefore, the parallel arrangement element 55-1 and the parallel arrangement element 55
A difference occurs in the amount of light received by -3, and an output voltage is output from the operational amplifier 62 connected to these and displayed on the display. Therefore, focusing can be performed.

In this case, since the amounts of light received by the vertically arranged elements 55-2 and 55-4 are equal, the output of the operational amplifier 61 is zero.

Furthermore, if the laser beam P is projected at the position shown in Figure 2(d) and the focal points are almost the same, the evaporative herdsman F will be at almost the highest height as shown in Figure 3fc). Or, the direction is biased towards the vertically arranged element 55-4.

Therefore, the operational amplifier 61 includes vertically arranged elements 55-4
A high output voltage is output to the side and displayed on the display.

Therefore, the projection position of the laser beam P can be adjusted.

Furthermore, if the laser beam P is projected at the position shown in Figure 2(e) and the focusing is poor, the evaporating herdsman F2 will become smaller and move in that direction, as shown in Figure 3(d). It is biased toward the vertically arranged element 55-2 side.

Therefore, the operational amplifier 61 includes the vertically arranged element 55-2.
A high output voltage is output to the side and displayed on the display.

Furthermore, since the output voltage is also output to the operational amplifier 62 connected to the parallel arrangement element 55-1, 55-3 and displayed on the display, focusing can be performed.

Although the effect of fillet welding has been explained, the laser welding device of the present invention can be applied to butt welding,
It has almost the same effect as fillet welding.

[Effects of the Invention] As explained above, the present invention uses an optical sensor having a group of photodiodes to receive and observe the evaporative herdsman, and focuses and aligns the laser beam. It has the following excellent effects.

That is, the structure of the laser light source section and the light condensing section, especially the structure of the optical system, is simplified, and the welding apparatus becomes inexpensive.

In addition, the condensing unit is smaller and lighter, making focusing and positioning operations easier and more accurate, improving welding quality.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the present invention, (a) is a diagram showing the configuration of a laser light source section, a condensing section, and an optical sensor, (b) is a connection diagram between an optical sensor and a detection section, and ( a)
, (b), (C), (d), (e), ge) are
A diagram of an evaporative herdsman during fillet welding, Figures 3 (a), (b), (CL) (d) are diagrams explaining the present invention in detail, Figure 4 is a configuration diagram of a conventional example, Figure 5 is a configuration diagram of another conventional example, and FIG. 6 is a configuration diagram of still another conventional example. In the figure, 1 is a laser light source, 3.8 is a condensing lens, 4 is a dichroic mirror, 9 is an optical fiber, 10, IOB is a racer light source, 15 is a TV camera, 16 is a lighting lamp, 19 is a video monitor, 20
, 20B is a condenser, 21 is a ferrule, 50 is an optical sensor, 51 is a detection head, 52 is an objective lens, 55 is a photodiode group, 55-1.55-3 is a parallel arrangement element, 55-2.55- 4 is a vertically arranged element, 60 is a detection section, 61 and 62 are operational amplifiers, 65 is a display device, and 101 and 102 are objects to be welded, respectively.

Claims (1)

[Claims] A laser light source section (10) incorporating a laser light source (1) for transmitting laser light (P) to an optical fiber (9); a condensing unit (20) that narrows down the laser beam (P) to a point; a pair of parallel elements (55-1, 55-3) arranged parallel to the laser beam (P); a pair of vertically arranged elements (55-2,
55-4) and a photodiode group (
55) and is set in the direction directly beside the evaporative flame (F) generated at the welding point, and a differential sensor that inputs the output of the parallel arrangement elements (55-1, 55-3). amplifier (62), the vertically arranged elements (55-2, 5
5-4), and a detection unit (60) equipped with a display (65) that displays the outputs of both differential amplifiers (62, 61), respectively; A laser welding device comprising: