JPS59104288A - Laser working device - Google Patents

Abstract

PURPOSE:To form the focus of laser light for working always automatically on the surface of a work in the stage of working a metal with a laser working device by converting photoelectrically the light reflected from the work and controlling a lens driving device by the electric power thereof. CONSTITUTION:An He-Ne laser beam 5b for aligning an optical system emitted from a CO2 laser device 4 is passed through a toric plane mirror 6, is made incident to a convex lens 8 by a plane mirror 7, and is focussed to a focal position. A material 1 to be worked is moved in a prescribed course from a start point P for working by a work table control device 3 according to the movement of a surface plate 2b in an X direction and the movement of a surface plate 2c in a Y direction. The CO2 laser beam 5a cuts or welds the work 1, and the light of the He-Ne laser beam reflected from the surface of the work is reflected at the toric part of the toric plane mirror and is converted to electric power by a photoelectric transducer 12. A lens driving device 19 is driven by a servocontrol device 13 according to said electric power, by which a cylindrical body 17 attached with a condenser lens 8 is moved to control the focus of the laser light so as to bring the same always on the surface of the work.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser processing device that can automatically align a laser beam spot on the surface of a workpiece.

To explain a conventional laser processing device with reference to FIG. 1, a laser beam for optical system alignment, for example, a HeNe laser beam 05b, generated by a laser device 04 is transferred to a first cylinder fixed to support stands 08a, 08b, and 08c. The signal is transmitted into the body 06 and reaches the mirror 010 fixed to the first cylindrical body 06. The laser beam 05b that has reached the mirror 010 is made incident on the lens 01B fixed to the lens holter 09a, and is focused into a spot at its focal position. Note: Lens halter
The nozzle 09b fixed to the nozzle 09a is normally structured to inject assist dregs, but is omitted for simplicity.

The workpiece 01 is the first. Second and eighth surface plates 02a.

02b, 02c, and first and second drive devices 02d
, 02c.

A lens drive device 011. which attaches a lens holder 09a to a second cylinder 07 fixed to a first cylinder 06. And the lens drive control device 014 moves the lens 013 in the optical axis direction, and the surface of the workpiece 01.
The focal position of the nozzle 013 marked 1 is matched visually. Note that the lens driving device 011 is the second cylinder body 0 of "2.
7 by fixing members 012a and 012b.

By workpiece full control device 03.

$1 and the second drive devices 02d and 02e are operated to match the spot of the laser beam 05b with the starting point P of laser processing, for example, cutting operation. 0 to laser device 04
02 laser heat is generated by the workpiece full control device 03.

While moving the workpiece 01 in the X and Y directions, it is cut, welded, or hardened into a predetermined shape.

In this way, with the conventional equipment, the 002 laser beam for processing (
+He-
The operator of the laser processing equipment visually observes the Ne laser heat laser beam and sets the workpiece, and during processing such as cutting, the operator observes the processing state through a protective mechanism. However, the liquid-added Nio A is moved, but this has the following drawbacks.

1. It is difficult to automate laser processing work because it is not possible to extract as an electrical signal whether the spot of the processing laser beam matches the surface of the workpiece.

1) Especially when the workpiece is not a flat body but a curved body,
It becomes difficult to match the Nupono I of the processing laser beam with the surface of the workpiece, and automation is difficult unless the shape and dimensions of the workpiece are known in advance. Therefore, it cannot be used for cutting spent nuclear fuel rods, etc.

The present invention eliminates the drawbacks of the conventional device u as described above, and provides a laser device and a device for processing a workpiece by transmitting a processing laser beam generated by a laser device to a workpiece through a laser processing optical system. An annular plane mirror is disposed in the laser beam transmission path between the optical system for laser processing, and a red light detection device is disposed in the reflected optical path of the annular plane mirror to detect red light and convert it into an electrical signal. We propose a laser processing device characterized in that a servo device is provided at the end of the device to operate a drive device d of a laser processing optical system in accordance with the electric signal.

The device of the present invention is equipped with an annular plane mirror that can detect the reflected light from the surface of the workpiece in the laser beam transmission path2, and detects the reflected red light and converts it into an electric signal to operate the driving device of the laser processing optical system. Since we have installed an automatic control device to do this, before processing begins.

At any time during processing, the laser torch can be adjusted automatically and the laser beam spot can be accurately aligned on the surface of the workpiece.

The accuracy and efficiency of laser processing can be significantly improved.

One embodiment-1 of the apparatus of the present invention will be explained with reference to FIGS. 2 and 3. First, in FIG. 2, which shows the overall configuration of the device.

1 is the workpiece + 28 is the first surface plate; 2b is the second surface plate fixed to the first surface plate 2a; 2c is the third surface plate fixed to the second surface plate 2b. , 2d is a first driving device that moves the second surface plate 2b in the X direction, 2e
3 is a second drive device that moves the third surface plate 2c in the Y direction, and 3 is a work table control device that operates the first and second drive devices 2d and 2c.

4 is a 002 laser device that generates a laser beam for processing (wavelength 106 μm) and also generates a HeNe laser beam (wavelength 0.L928 μm) for optical system alignment; 5a is a CO2 laser beam for processing; 5b is a CO2 for processing This is a HeNe laser beam for optical system alignment that propagates in the same direction as the laser beam 5a.

6 is an annular plane mirror whose central portion allows the laser beam to pass through and whose outer peripheral portion reflects the laser beam.

7 is a plane mirror that reflects the laser beam, and 8 is a first convex lens that focuses the laser beam into a spot at its focal position.

9 is a red filter that allows only visible light with a wavelength of 0.63287 zm to pass through; 10 is a second convex lens that focuses the visible light that has passed through the red filter 9 into a spot at its focal position; and 11 is, for example, 500 μm in diameter. 12 is a photoelectric conversion element such as a photodiode or a phototransistor, and 13 is a servo device that operates a lens driving device 19, which will be described later, so that the output voltage of the photoelectric conversion element 12 is maximized. be.

14 is a first cylindrical body to which the annular mirror 6 red filter 9 and flat mirror 7 are fixed, 15 is a support base to which the first cylindrical body is fixed, and 16 is the first (7) cylindrical body. 14 is a second cylindrical body into which a convex lens holder 17 is inserted; 17 is a convex lens holder 118 to which the first convex lens 8 is fixed; a nozzle is fixed to the convex lens holder 17; Note that this nozzle has a structure to eject assist scum; however, this is omitted for the sake of simplicity.

19 receives a signal from the servo device 18;

- A lens driving device for moving the convex lens holder 17 in the optical axis direction of the first convex lens 8; 20 is a fixing member that fixes the lens driving device 19 to the second cylindrical body 6;

The operation of laser cutting a curved object in this device will be explained as follows.

HeN for optical system alignment notebook generated by laser device 4
The e-laser beam 5b is transmitted into the first cylindrical body 14 fixed to the support stand 15, passed through the annular plane mirror 6 fixed to the first cylindrical body 14, and then the e-laser beam 5b is transmitted to the plane mirror 7.
reach. Laser beam 5 reaching plane mirror 7
The light beam b is made incident on the first convex lens 8 fixed to the convex lens holster 17, and is focused into a spot at its focal position.

The workpiece 1 is placed in the first. Second and third surface plates 2a.

2b, 2c, and first and second drive devices 2d, 2
It is fixed to the work table-F consisting of e. In this case, the position of the starting point P of laser processing is (x
, Y) coordinates are determined as (Xo, Yo), for example, and the processed side 1 is installed in consideration of that point (Xo, Yo).

The HeNe laser beam is focused by the first convex lens 8, but even if the spot does not match the surface of the workpiece 1, a part of the light reflected from the surface is The light enters a convex lens 8, becomes parallel light, and enters a second convex lens 10 via a plane mirror 7, an annular plane mirror 6, and a red filter 9. The light is then focused by the second convex lens 10, passes through a pinhole 11 installed at its focal point, and enters the photoelectric conversion element 12. The photoelectric conversion element 12 generates a voltage pj compared to the intensity of the incident light, and transmits it to the servo device 13. The servo device 18 sends an actuation signal to cause the first convex lens 8 to reciprocate in the direction of its optical axis. The lens driving device 19 is actuated by a signal from the servo device 13, and the convex lens halter 1
A reciprocating motion is applied to the first convex lens 8 in the direction of its optical axis via the lens 7.

The first convex lens 8 first moves, for example, toward the workpiece l side, and in that direction, the spot of the He-Ne laser beam approaches the surface of the workpiece 1 (if the direction is -h light distribution electric conversion element 12 The output voltage increases. When the spot of the HeNe laser beam and the surface of the workpiece 1 match, the photoelectric conversion element 12 has the maximum output voltage. Then,
-1- When the position of the spot and the surface of the workpiece shifts.

The output voltage of the photoelectric conversion element 12 decreases. When the output voltage starts to decrease, the servo device 13 controls the position of the first convex lens 8 indicated by -f- through the lens drive device 19 in a direction in which the output voltage increases. The surface of the workpiece 1 and the spot of the HeNe laser are controlled to always coincide with each other by the method described below.

Regarding the optical system for detecting the reflected light from the workpiece of the 1-1eNe laser beam with a photoelectric conversion element.

The explanation below will be supplemented with an explanatory diagram of the optical system in FIG. 3a and an equivalent system diagram in FIG. 3b. Figure 3a is a redrawing of only the optical system in Figure 2;

This is an optical system equivalent to that. In Figure 3a.

On the surface of the workpiece 1, the H light is focused by the first convex lens 8.
e Ne relay hem 5b is scattered. A portion of the scattered light enters the first convex lens 8.

The light becomes parallel light and enters the second convex lens 10 via the plane mirror 7 and the annular plane mirror 6.

Pass through pinhole 11. In this case, as shown in FIG. 3, if the surface of the workpiece 1 is at the focal point of the first convex lens 8, most of the scattered light on that surface will be focused by the second convex lens 10. Been.

Pass through pinhole 11. However, in FIG. 3, when the surface of the workpiece 1 is at a position 1b shifted from the focal point of the first convex lens 8, most of the light focused by the second convex lens 10 is , it becomes impossible to pass through the pinhole 11. Therefore, the strength of the light passing through the pinhole 11 is as follows.

It is determined by the relationship between the position of the surface of the workpiece 1 and the focal point of the first convex lens 8, that is, the spot position of the f(e-N e laser).

The third surface plate 2C is operated by the workpiece full control device a, Igt and the second drive device 2d, 2e according to a trajectory based on a preset x-yl reference system display.

Regarding the start of its operation.

A start signal is transmitted from the workpiece full control device 3 to the laser device 4.

When the laser device 4 receives an operation start signal from the work table control device 3, it stops generating the +He--Ne laser beam and generates a C02 laser beam 5a (wavelength: 10.67 zm). The 0C12 laser beam 5a passes through a two-ring annular mirror 6, and then via a plane mirror 7 and a first convex lens.

The light is focused on the cutting start point P, and cutting is started.

002 When cutting by the laser beam starts.

Visible light is generated from the cutting location due to high heat melting of the workpiece 1. The visible light is detected by the same method as the above-mentioned detection of the reflected light of the 1-1e Ne relay beam by the photoelectric conversion element.
First convex lens 8. Plane mirror 7, annular plane mirror 6
, red filter 9° via second convex lens 10 and pinhole 11.

The light is incident on the photoelectric conversion element 12. However, red filter 9
Therefore, only red light (wavelength 0.6828 μm) is incident. The output voltage of the photoelectric conversion element 12 is then used by the servo device 13 in the same manner as described above.

The workpiece 1 is moved in the X direction by the workpiece full control device 3 and the worktable. The workpiece 1 has a curved surface, and the spot of the co2 beam and the surface of the workpiece are misaligned (002
As the energy density of the laser beam at its surface is reduced, the high thermal melting of the cut location is reduced. the result,
The intensity of visible light, that is, red light due to high-temperature melting decreases, and the output voltage of the -h light distribution electric conversion element 12 decreases.

Once its output voltage begins to transition to a state of decline.

By the servo device 13 and the lens drive device 19.

The position of the first convex lens 8 is changed in the same way as described above. Therefore, while the workpiece 1 is moved in the X direction, the spot of the C02 laser beam always coincides with the surface of the workpiece l.

When the workpiece table moves according to a preset trajectory and completes its operation, the worktable controller 8 sends a signal to the CO2 laser 4. and,
002 The laser device 4 stops generating the laser beam,
The cutting process is completed.

Due to one or more actions, this device has the following effects.

In conventional equipment, in order to focus the spot of the processing laser beam on the surface of the workpiece, the operator of the laser processing equipment either visually observes the workpiece or measures the workpiece whose shape and dimensions are accurately known in advance. In some cases, the work table was moved along a predetermined trajectory. For this reason, it is difficult to automate laser processing for workpieces whose shape and dimensions are not accurately known, such as when disassembling spent nuclear fuel rods, and this method has not been practically usable.

According to the apparatus of the present invention, the laser processing torch can be moved and adjusted so that the spot position of the processing laser beam always matches the surface of the workpiece, even when the shape and dimensions of the workpiece are not accurately known. Processing such as laser cutting, welding, and hardening is now possible.

In particular, the ability to perform laser processing, such as cutting spent nuclear fuel rods, which was impossible with conventional equipment, has a significant effect from an industrial standpoint.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional laser processing device, and FIG. 2 is a generally equivalent diagram of an embodiment of the laser processing device of the present invention. 1...Work material, 28~2c...Surface plate, 2d~
2e... Drive device, 8... Workpiece full control device. 4...CO2 laser device +5a...Laser beam for processing, 5b・°・Saheem for alignment,
6... Annular plane mirror, 9... Red filter,
8゜10...Convex lens, 11...Pinhole, 1
2... Photoelectric conversion element, 13... Servo device, 19.
...Lens drive device.

Claims (1)

[Claims] In a device that transmits and processes a processing laser beam generated by a laser device to a workpiece through a laser processing optical system, an annular plane is provided in the laser beam transmission path between the laser device and the laser processing optical system. A red light detection device is installed in the reflected optical path of the annular plane mirror to detect red light and convert it into an electrical signal, and the output end of the detection device is connected to a laser processing optical system according to the electrical signal. A laser processing device characterized by being provided with a servo device for operating a drive device.