JPS6186087A - Laser working device - Google Patents

Abstract

PURPOSE:To execute precise laser working such as laser cut, etc. by providing a distance control means for controlling so that a distance between a working work and a working lens is kept constant. CONSTITUTION:A radiant beam emitted from a light source 7 is focused by a projection lens 8, and irradiated as an optical spot at the same position as a laser beam 1 on a work surface of a working work W. A photodetecting lens 9 executes an image pickup of the optical spot on the work surface, and forms an image of the optical spot on a photodetecting surface of a photodetector 10. The photodetector 10 which has detected this optical spot image generated an electric signal corresponding to an image formed position of the optical spot image. A processing circuit 11 executes an operation and sends out a distance output. That is to say, an electric signal for controlling the position of a working use lens 2 is outputted so as to keep a distance l constant. Accordingly, the position of the lens 2 is adjusted, and the distance between the work surface of the working work W and the lens 2 of a working head 20 is controlled so that it always becomes constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a processing workpiece V (a laser processing apparatus that performs laser processing by irradiating a laser beam, particularly a processing head).

[Conventional technology]

FIG. 2 is a sectional view of a processing head of a conventional laser processing device. In the figure, (1) is the CO1 laser beam that is the main component in laser processing, (2) is the processing lens for finely focusing the metal, and (3) is the tip formed to be thin to make the assist gas flow at high speed. (4) is a lock nut for fixing the nozzle (3) at a predetermined nozzle position,
(5) shows the machining workpiece (G) and the nozzle (3) of the machining head ■.
) is a contact-type scanning sensor that maintains a constant distance from the

A conventional laser processing device is configured as described above. For example, a laser beam (1) emitted from a laser oscillator (not shown) is reflected by a plurality of mirrors and then reaches the processing head. Lens for machining wire (2)
The beam is focused and irradiated onto the workpiece (g), where it is used for precision machining such as laser cutting and laser welding.

When the workpiece (G) is a two-dimensional flat plate and laser cutting is performed on it, even if the workpiece (4) has some irregularities such as "warpage", the equipped contact copying machine ( 5), the focal position of the laser beam (2) is always kept constant, resulting in good cutting.

[Problem that the invention seeks to solve]

By the way, when laser cutting a three-dimensional three-dimensional processing workpiece, which has been rapidly increasing in V in recent years, the attitude of the processing head is controlled and the V nozzle (3
1f, if the direction is too low, a good cut cannot be obtained. Further, it is necessary to maintain a constant distance between the work surface and the nozzle (3) or the processing lens (2).

However, with conventional laser processing equipment such as the one mentioned above,
vC1 to keep the focal position of the laser beam (2) constant.
A contact-type copying sensor (5) is used, but the contact-type copying sensor (5) can achieve a high degree of accuracy.Moreover, in the corners of the three-dimensional surface with small curvature, the contact-type copying sensor (5) is able to produce a high level of accuracy. There was a problem that the workpiece was too large to be used.1 This invention was made to solve this problem. The object of the present invention is to obtain a laser processing device that can perform laser processing such as cutting with good quality by always keeping the distance between the lens and the processing lens of the processing head constant.

[Failure to solve the problem]

The laser processing equipment according to the present invention includes a light projector that focuses a radiation beam from a light source and irradiates a light spot of an appropriate size onto a workpiece, and an image of the light spot on the workpiece. A light-receiving lens and a photodetector that sends an electric signal corresponding to the position of the original spot image imaged by the light-receiving lens; The apparatus is comprised of a processing circuit that outputs an electric signal to control the distance between the workpiece and the processing lens to be kept constant, and is provided with a distance control means to control the distance between the workpiece and the processing lens to be kept constant.

[Operation] ” In the present invention, an image of a light spot on the surface of the workpiece of a radiation beam irradiated onto the workpiece by a light source and a light projecting lens is captured by a light receiving lens, and the light spot image captured by the light receiving lens is is detected by a photodetector, and a processing circuit that receives an electrical signal corresponding to the imaging position of the light spot sent out from the photodetector calculates the distance between the processing workpiece and the processing reno, and keeps the distance constant. An electrical signal is output to control the distance between the workpiece and the processing lens to be maintained at a constant value of 1'L.

〔Example〕

FIG. 1 is a sectional view showing an embodiment of the present invention. In the figure, (1) indicates CO, which is the main ingredient in laser processing.
Laser beam 7 (2) is emitted by a nozzle of the processing head whose tip is formed into a thin shape and has the effect of increasing the flow of assist gas at high speed tC.

Reference numeral (7) denotes a light source that emits a radiation beam, and is provided at a position V in contact with the upper part of the nozzle (3). (8) is the light source (
6) a projection lens that focuses the emitted radiation beam;
(9) Photographs the light spot image of the radiation beam on the surface of the workpiece irradiated with the radiation beam.
This is a light-receiving lens that is L-shaped, and is provided adjacent to the upper part of the nozzle (3) at a position substantially symmetrical to the light-emitting lens (8) with the entire center of the nozzle (3). Qo is a photodetector comprised of a non-contact optical sensor that generates an electrical signal corresponding to the imaging position of a light spot image, and its light-receiving surface is placed on the imaging surface of the light-receiving lens (9). There is. (11) is a processing circuit that processes the output signal of the photodetector diagram and outputs an electric signal for controlling the position of the processing lens (2).

As a result, the distance control means for controlling the distance between the workpiece (g) and the machining lens (2) of the machining head (7) to be kept constant is the light source (7), the light emitting/zoom ( 8), a light receiving lens (9), a photodetector and a processing circuit (11).

In the laser processing apparatus configured as described above, the light source (7
) is emitted by a projection lens (8).
The laser beam (1) is bundled and irradiated onto the workpiece M as the original spot at the same position as the laser beam (1).

Then, the light receiving lens (9) captures an image of the original spot on the workpiece surface, and forms an image of the medical light spot on the light receiving surface of the original detector. The photodetector that detects this light spot image is also called, for example, an original position detector, and generates an fc electric signal depending on the imaging position of the original spot image. That is, based on the values of currents iA and 1B generated by the two electrodes of the photodetector αq, the imaging position P of the light spot image is expressed by the following equation (1) VC.

Since the output of the photodetector αO is proportional to the position and intensity of the light spot image, in equation (1) above, the intensity change of the light spot image is divided by (iA+jB), and the light The samurai has a blade that is proportional only to the position of the spot image.

On the other hand, the light point of (9) (Pll,
(From P21, the distance A to the workpiece surface of the processed workpiece <VV> is expressed by the following equation (2).

In this equation (2), L is the light point (Pl) of the projection lens (8)
The distance between and the light point (P2) of the light receiving lens (9) is ψ
is the angle between the optical axis of the laser beam irradiated onto the workpiece surface and the projection optical axis of the radiation beam irradiated onto the workpiece surface by the projector (8), and θ is the origin of the laser beam. This is the angle between the axis and the receiving optical axis of the radiation beam incident on the receiving lens (9). Among these, L and ψ are fixed values determined only by the configuration of the device. Further, θ is determined by the above-mentioned position ItP of the original spot image and the focal length and installation position of the light receiving lens (9), but the values other than P are fixed values.

In other words, the light point CP of the light emitting/receiving lens (87, (9))
l, (P, ) The distance A to the workpiece surface of the recessed workpiece (5) is only the imaging position P of the light spot image corresponding to the displacement of the workpiece surface, that is, the output of the photodetector αno'NL. The currents iA and iB can be determined as variables.

In addition, the distance l between the workpiece surface of the processed workpiece (4) and the processing lens (2) of the processing head is also
) can be calculated by adding a certain constant to the distance A from the light point (PHI, (Pt)) to the workpiece surface, so the distance l between the workpiece surface and the processing lens (2) can be expressed as the following equation (3): It can be calculated. t = KP ・・・・・・
Song...(3) Here, K is an installation constant, which is a fixed value and is determined by prior calculation or actual measurement.

The processing circuit CIQ executes the above calculation and sends out the distance output, that is, the processing lens (2
) outputs an electrical signal that controls the position of the Therefore, the processing head driving device (not shown) is driven by the electric signal, and the position of the processing lens (2) is adjusted, and the workpiece surface of the processing workpiece (5) and the processing head (7) are aligned.
&lI so that the distance between the
The beam waist of the laser beam (1) is always located at the surface of the workpiece, and the optimum processing condition is maintained.

However, in the above embodiment, an optical position detector is used as the photodetector, but CC is used as the photodetector αq.
A linear seven-sensor array such as D may also be used, and the same effect can be obtained in this case as well.

Furthermore, a window for removing foreign matter from the surface of the workpiece during laser processing or an optical filter for removing the influence of optical noise during laser processing may be inserted into the radiation beam projection/receiving optical system.

Furthermore, it goes without saying that the light source (6) may be subjected to intensity modulation, and only this modulation frequency may be selected and processed on the light receiving side.

〔Effect of the invention〕

As explained above, the present invention includes a light source, a light projecting lens, V [therefore, an image of the radiation beam irradiated onto the workpiece on the workpiece surface is captured by the light receiving lens, and a light spot image captured by the light receiving lens VC]. is detected by a photodetector, and a processing circuit that receives an electrical signal corresponding to the imaging position of the light spot sent out from the photodetector calculates the distance between the processing workpiece and the processing lens, and calculates the distance between the processing workpiece and the processing lens. distance control means e configured to output an electrical signal for controlling to maintain t
This makes it possible to control the distance between the workpiece and the machining head of the machining head to keep it at one foot, so even if the workpiece is a three-dimensional object with complex unevenness, the distance between the workpiece and the The distance between the workpiece surface and the processing lens of the processing head is always constant, which has the effect of allowing precise laser processing such as laser cutting.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view of a processing head of a conventional laser processing apparatus. In the figure, (1) is the laser beam, (2) is the processing lens, (3) is the nozzle, (7) is the light source, (8) is the light projecting lens, (9) is the light receiving lens, (IQ is the light detection 1, OP is a processing circuit, and (4) is a processed workpiece.The same reference numerals in each figure indicate 4 or equivalent parts.・Essence 1゛10・Mr. 9-th 11; Foot-embedding cycle W・no5-Fu 7

Claims (2)

[Claims] (1) In a laser processing device that performs laser processing by irradiating a laser beam onto a workpiece, a distance control means is provided to control the distance between the workpiece and a processing lens that focuses the laser beam to be kept constant; The distance control means is
A light source that emits a radiation beam, a projection lens that focuses the radiation beam from the light source and irradiates a light spot of an appropriate size at the same position where the laser beam is irradiated onto the workpiece, and the workpiece. a light-receiving lens that images the light spot above, and a photodetector that has a light-receiving surface placed on the imaging surface of the light-receiving lens and sends out an electrical signal corresponding to the position of the light spot image formed by the light-receiving lens. and a processing circuit that calculates the distance between the workpiece and the processing lens based on the electrical signal from the photodetector and outputs an electrical signal that controls the distance to be kept constant. . (2) The laser processing apparatus according to claim 1, wherein the photodetector is an optical position detector.