JPS59193779A - Laser welding device - Google Patents

Abstract

PURPOSE:To set small the deviation of a condensing system optical axis and to perform seal welding of a pipe diameter smaller than the diameter of a laser beam prior to condensation by changing specific times the optical axis direction of the laser beam. CONSTITUTION:An optical system device 23 consists of a reflecting system and a condensing system. The reflecting system is combined with four pieces of reflection mirrors 28-31, by which the optical axis direction is changed four times to deviate a laser beam 24 for working at a prescribed small deviation L relative with a revolving shaft 25. The condensing system is constituted of a convex lens 32 which condenses the beam deviated by the reflecting system to a beam focus F. The device 23 is rotated so that the focus F of the condensed beam draws a circumference with the shaft 25 as a center and the deviation L as a radius. A piece of reflection mirror 31 is formed of a dichroic mirror having the function to reflect the light of the wavelength region of the laser beam 24 and to allow transmission of visible light. A monitor device 33 is installed behind the mirror 31 to photograph the part near the weld zone.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser welding device for performing seal welding between tubes and tube sheets of a heat exchanger.

FIG. 1 is a sectional view of a heat exchanger, in which 1 is a hollow hole, 2 is a tube plate, 3 is a tube, and 4 is a hole provided for welding the tube plate 2 and the tube 3. This hole 4 is about 1.5 times the diameter of the pipe and is covered by welding a plug after the welding of the legs and soles is completed.

A conventional laser welding device for welding the tube plate 2 and the tube 3 is shown in FIG. In this device, an optical system device 7 is mounted in a laser head fixing frame 5 via a bearing 6 so as to be rotatable around the input source axis of a processing laser beam 8. This optical system device 7 includes a reflection system consisting of two total reflection mirrors 10 and 11 that decenters the original axis direction of the laser beam for processing from the rotation axis 9 of the optical system device 6, and a processing device that is decentered by the reflection system. and a condensing system provided with a convex lens 12 for condensing the laser beam.

Then, by rotating the optical system device 6 around the rotation axis 9 by the motor 13 and the gear 14, rotational movement under the beam focal point F is provided. Note that instead of the reflecting mirror 1 and the focusing light lens 12, a concave mirror is placed at the position of the reflecting mirror 11,
There are also examples in which this concave mirror has a reflecting and condensing function.

Since this laser welding device uses two reflecting mirrors 10° and 11 to decenter the optical axis from the rotational axis, the diameter that can be welded circumferentially due to its mechanism is at least 3 to 3 times the diameter of the laser beam 8.
It becomes 4 times. However, the actual pipe diameters of various heat exchangers are approximately the same as the laser beam (20 to 40 wnφ), and therefore the conventional ones are inappropriate.

Furthermore, when applying the optical system shown in FIG. 2 to the heat exchanger shown in FIG. I will do it. However, in this case, the part to be welded cannot be visually observed from the outside, and it is impossible to monitor the part to be welded from the outside, such as adjusting the welding target position.

The present invention has been made in view of the above circumstances, and its object is to provide a laser welding device that is capable of small-diameter circumferential welding and that is also capable of monitoring a narrow welded area.

That is, the present invention includes a reflecting system having a plurality of reflecting mirrors for decentering the optical axis direction of a laser beam for processing, and a focusing system having a convex lens or a concave mirror for focusing the decentered laser beam in the reflecting system. In the laser welding apparatus, the optical system device is configured to be rotatable around the input optical axis of the processing laser beam, and the processing laser beam is rotated circumferentially by the rotation of the optical system device. ,
The optical axis direction of the laser beam is changed at least four times, and one of the reflecting mirrors or the concave mirror is formed of a dichroic mirror that reflects light in the wavelength range of the processing laser beam and transmits visible light, and further A feature is that a monitoring device for monitoring the bath contact area is placed behind the dichroic mirror.

The present invention will be explained below with reference to the embodiment shown in FIG.

The illustrated laser welding device has a laser head fixing frame 21.
An optical system device 23 is rotatably mounted therein via a bearing 22. This optical system device 23 is rotationally driven by a motor 26 and a gear 27, with the input optical axis of the processing laser beam 24 serving as a rotation axis 25. The optical system device 23 consists of a reflection system and a condensing system. The reflection system has 4 reflections @28~
31 are combined so that the optical axis direction is changed four times, so that the processing laser beam 24 is eccentric with respect to the rotating shaft 25 by a predetermined small eccentricity amount. The condensing system focuses the laser beam 24' decentered by the reflection thread at a beam focus A.
It is composed of a convex lens 32 that focuses light on F.

By rotating the optical system device 23, the beam focus F of the condensed Radhe beam 24' forms a circumference with the rotation axis 25 as the center and a radius of eccentricity Li.

Further, one reflecting mirror 31 is formed of a dichroic mirror that has the function of reflecting all light in the wavelength range of the processing laser beam 24 and transmitting visible light. Behind this reflecting mirror 31, a monitoring device 33 such as a television camera is installed at a position facing the object to be welded (not shown), and is configured to take pictures of the vicinity of the welding part. Further, this image is displayed on a TV monitor device (not shown) or the like.

In addition, in the present invention, as shown in FIG.
43 constitutes a reflection thread, and a concave mirror 44 made of a dichroic mirror constitutes a condensing thread.Furthermore, a monitoring device 33 is placed behind this concave mirror 44, and the original axis of the laser beam 24 is changed four times to determine eccentricity. It may be possible to reduce the amount.

Further, in the present invention, the optical axis of the laser beam may be changed five times or more in total. The point is to combine the reflection system and the condensing thread so that the amount of eccentricity is small.

However, according to this Lede beam welding device, the optical axis can be
Since the change is made more than once, it is possible to set the amount of the focusing thread ye axis to a small value, and it is possible to connect the tube diameter to a tube diameter smaller than the diameter of the laser beam before focusing.

In addition, since the welded area is monitored through dichroic and Kumirr metal, it is possible to monitor the welded area well even in cases where it is difficult to monitor the welded area, such as 7-hole welding in a narrow area of a heat exchanger. It can be very effective in alignment work, etc.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a bath contact point between a tube sheet and a tube, FIG. 2 is a sectional view of a conventional laser welding device, and FIG. 3 is a sectional view of a Rede welding device showing an embodiment of the present invention. FIG. 4 is a sectional view of a laser welding device showing another embodiment of the present invention. 2... Laser head fixing frame, 22... Bearing, 23... Optical system device, 24... Laser beam for processing, 25... Rotating shaft, 26... Motor, 27... Gear , 28-31...Reflector, 32...Convex lens, 33
・Supervisor 1 device, 41-43...Reflector, 44 ・Concave mirror. Applicant's sub-agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] An optical system device comprising a reflection system having a plurality of reflection mirrors for decentering the optical axis direction of a processing laser beam, and a condensing system having a convex lens or a concave mirror for condensing the decentered laser beam in the reflection system. , a laser welding device configured to be freely rotatable around the input optical axis of a laser beam for processing, and to rotate the laser beam for processing in a circumferential shape by rotation of the optical system device, the optical system device described above The optical axis direction is changed at least four times, and one of the reflecting mirrors or the concave mirror is formed of a dichroic mirror that reflects light in the wavelength range of the processing radar beam and transmits visible light, and the dichroic mirror A laser welding device that has a monitoring device placed behind it to monitor the welding area.