JPH06262383A - Laser beam machine - Google Patents

Abstract

PURPOSE:To keep an interval between a ftheta lens being continuously worked in a wide range and a surface to be worked constant by controlling the position of a laser beam machining head according to a detected result by a sensor so that a prescribed interval is kept between a laser beam machining head and an object to be worked, and performing a laser beam machining to a surface to be worked. CONSTITUTION:According to a laser beam machine, a laser beam machining is performed while always watching an interval between the ftheta lens 7 of a laser beam head 1 and a surface P to be worked by a distance sensor 13. So, even when there is a warp and an undulation on the object P to be worked, the intensity of a laser beam irradiating a surface to be worked, a spot diameter, etc., can be correctly controlled. Therefore, it has an large effect on heightening the working accuracy of a marking on a steel sheet P with a large surface area. Also, working accuracy can be further improved by correcting the shift of a mounting position between the sensor 13 and the laser beam head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for marking characters and the like on a surface of a steel plate or the like at high speed.

[0002]

2. Description of the Related Art As an example of a technique for marking a surface of an object such as a steel plate with a laser beam, a galvano scanner for scanning a laser beam from a laser light source in a desired direction and the galvano scanner A laser marking device which makes it possible to move a laser head having an f.theta.
No. 0-106686.

According to this publication, first, a laser head is moved at a marking start position and fixed at that position, marking is performed within a scannable range by a galvano scanner, and then the laser head is moved by a predetermined distance. And fix it in that position,
Marking is performed while scanning again with the galvano scanner, which is faster than the XY driving method in which the marking is performed while driving the entire laser head along the marking characters.

In such a laser processing apparatus using a galvano scanner and an fθ lens, a surface to be processed having a predetermined width can be processed at a high speed while the fθ lens is fixed, but there is a problem such as the depth of focus of laser light. It is necessary to more accurately maintain the distance between the fθ lens of the laser head and the surface to be processed, that is, the focal length within a predetermined range, as compared with an apparatus that performs marking while driving the entire laser head.

[0005]

However, for example, a steel plate or the like does not always have a flat surface to be machined due to warpage or the like, and even if the laser head is set so that the above-mentioned interval becomes constant at the start of marking, the laser head is not processed during machining. There is a risk that the spacing may change and the quality of the engraved characters may deteriorate.

The present invention has been devised in order to eliminate such inconveniences of the prior art, and its main purpose is to provide a gap between the fθ lens of the laser head and a surface to be processed during continuous wide area processing. It is an object of the present invention to provide an improved laser processing apparatus capable of keeping a constant value.

[0007]

According to the present invention, a galvano scanner for scanning a laser beam from a laser light source in a desired direction and a laser beam from the galvano scanner have a predetermined same object. A laser head having an fθ lens for converging light on a flat surface, and means for supporting the laser head so that the laser head can be moved toward and away from a surface to be processed of a workpiece and movable along the surface to be processed. The laser processing head includes a sensor that detects a distance between the laser head and the surface to be processed, and the laser processing head based on a detection result of the sensor so that the laser processing head and the surface to be processed have a predetermined distance. And a means for performing laser processing on the surface to be processed while controlling the position of the laser processing apparatus.

[0008]

According to this structure, the distance between the fθ lens of the laser head and the surface to be processed is always detected by the position sensor, and the distance is always constant even if the workpiece is warped or undulated. Can be controlled.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to specific embodiments shown in the accompanying drawings.

FIG. 1 is a partial sectional side view showing the configuration of a laser processing apparatus constructed according to the present invention. This device is for imprinting characters or the like on the surface of a steel plate P as a workpiece.

Guide means 2 is provided in the width direction (X direction) of the steel plate P.
The laser head 1 movably supported by the motor 3
It is designed to be driven with. Further, the laser head 1 and the base 1a are in the vertical direction, that is, close to the steel plate P.
It comprises a Z-direction movable portion 1b movably supported by the base 1a by the guide means 4 in the separating Z-direction. The Z direction movable portion 1b is driven by a motor 5.

An fθ lens 7 is provided at a position facing the steel plate P in the Z direction movable portion 1b of the laser head 1. The fθ lens 7 has galvanometer mirrors 8a and 8b.
A laser beam is supplied from the laser oscillator 6 via the galvano scanner 8 having the mirrors and the mirrors 9 to 12. Here, the fθ lens 7 is a lens whose focal position moves on one plane orthogonal to the optical axis depending on the incident angle. That is, the focus position of the laser emitted from the fθ lens 7 moves on the surface of the steel plate P within a predetermined range due to the change of the incident angle by the galvano scanner 8.

On the other hand, in order to detect the distance between the fθ lens 7 and the steel plate P in the moving direction of the laser head 1 in the vicinity of the fθ lens 7 in the laser head 1, that is, in the position in front of or behind the X direction. The distance sensor 13 is provided. The distance sensor 13 is a control unit 1 for driving and controlling the motor 3, the motor 5, and the galvano scanner 8.
4 is connected.

The operating procedure of this embodiment will be described below. A marking area 15 is preset on the steel plate P, and for example, 20 characters are laser-marked on the marking area 15. Here, the engraved area 15 is, for example, four areas (A, B, C, and C) defined by the scanning range (or the size of the fθ lens 7) of the galvano scanner 8 and the relationship between the focus retention and the amount of warpage or waviness of the steel plate.
D).

First, the steel plate P is transported by the transport roll 16 and placed thereon, and the distance sensor 13 of the laser head 1 is moved by the motor 3 to the marking start position of the marking region 15 (center of the region A). Then, the distance sensor 13 detects the distance between the fθ lens 7 and the steel plate P at the center of the area A, and the Z-direction movable portion 1b is moved to the motor 5 based on the detection result.
The fθ lens 7 and the focal length of the fθ lens 7 are made to coincide with each other. Then, the center of the fθ lens 7 is moved to the center of the area A, and the galvano scanner 8 is actually scanned to mark the area A.

Next, the distance sensor 13 of the laser head 1 is moved to the center of the area B of the marking area 15 by the motor 3, and the distance sensor 13 sets the distance between the fθ lens 7 and the steel plate P at the center of the area B. After detecting and driving the Z-direction movable portion 1b with the motor 5 based on this detection result, f
The center of the θ lens 7 is moved to the center of the region B, the galvano scanner 8 is actually scanned, and the region B is marked.

Similarly for the areas C and D, the distance sensor 13 detects the distance between the fθ lens 7 and the steel plate P at the center of the area, and the distance and the focal length of the fθ lens 7 are matched. Make a stamp.

The distance sensor 13 detects the distance between the f.theta. Lens 7 and the steel plate P at the center of the area A, and after matching this with the focal length of the f.theta. It is needless to say that the regions A to D may be continuously marked based on the displacement (warpage or waviness amount) data of the steel sheet surface after scanning the regions B to D and performing the same measurement.

[0019]

As described above, according to the laser processing apparatus of the present invention, since the laser processing is performed while always monitoring the interval between the laser head and the surface to be processed by the sensor, the object to be processed is warped or undulated. However, since the intensity of the laser applied to the surface to be processed, the spot diameter, and the like can be accurately controlled, a great effect can be exerted in increasing the accuracy of the marking on a steel sheet having a large surface area. Further, by correcting the mounting position deviation between the sensor and the laser head, the processing accuracy can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional side view of a laser processing apparatus to which the present invention has been applied.

FIG. 2 is a view taken along the line II-II of FIG.

[Explanation of symbols]

 1 laser head 1a base 1b Z direction movable part 2 guide means 3 motor 4 guide means 5 motor 6 laser oscillator 7 fθ lens 8 galvano scanner 8a, 8b galvano mirror 9-12 mirror 13 distance sensor 14 control unit 15 engraving area 16 carrier roll P Steel plate A, B, C, D area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Saito 46-59 Nakahara, Tobata-ku, Kitakyushu City Nippon Steel Corporation Machinery & Plant Division (72) Inventor Yukihisa Fukuda 46-59 Nakahara, Tobata-ku, Kitakyushu City Nittetsu Plant Design Co., Ltd.

Claims (1)

[Claims] 1. A laser head having a galvano scanner for scanning a laser light from a laser light source in a desired direction, and a laser head having an fθ lens for condensing the laser light from the galvano scanner on a predetermined plane. The head is close to the work surface of the work piece /
And a sensor for detecting a distance between the laser head and the surface to be processed, the means for supporting the laser processing head and the surface to be processed. And a means for performing laser processing on the surface to be processed while controlling the position of the laser processing head on the basis of the detection result by the sensor so as to be at a predetermined interval.