JPH02217188A - Laser beam machining head - Google Patents

Abstract

PURPOSE:To enhance the accuracy of laser beam machining by detecting the emitting position of a condensed laser beam through a sensor at the opening part of a nozzle and automatically moving a machining lens in the direction rectangular to the emitting direction of the laser beam. CONSTITUTION:The laser beam 1 is condensed by a working lens to bring the surface of a material 8 to be worked into focus 9. Thermosensitive sensors 15a, 15b set on the nozzle 7 sense the inclination of the laser beam 1, send a signal to an arithmetic controller 16 and the signal elongates or contracts voltage driving elements 13a, 13b. The lens holder 3 supporting the working lens 4 moves against the spring pressure of coil springs 14a, 14b and the emitting place in the opening part 7 of the condensed laser beam can be adjusted to a prescribed position. Adjusting operations for the laser beam axis and the nozzle part are not required and the place of the condensing laser beam is always fixed and, as a result, the working accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser processing head that constantly controls the focusing position of a laser beam applied to the tip of the processing head of a laser processing machine.

[Conventional technology]

FIG. 8 is a cross-sectional view showing the configuration of a conventional laser processing head.
(5) is a processing gas cylinder, (6)
) is the processing gas inlet provided in the main body (2), and (7) is the processing gas inlet coaxially with the focused laser beam from the nozzle QO at the tip of the processing head main body (2) to the workpiece (8).
(9) is the opening for emitting the laser beam to (1)
This is the focal point on the workpiece (8).

Next, the operation will be explained. The laser beam (1) is focused by the processing lens (4) and irradiated onto the workpiece (8), and in laser cutting, etc., the processing gas cylinder (5) is
Using 02 gas, the workpiece (8) is processed by emitting 02 gas coaxially with the laser beam (1) from the opening (7) of the nozzle portion α1. Opening of nozzle αQ at this time (7)
The diameter φα is set to improve machining performance and reduce the amount of machining gas.
Generally, in the case of (X)2 laser cutting, φ1.5 to 8
ff culmness is applied.

In this type of laser processing head, it is important that the emission position of the focused laser beam at the aperture (7) is at the center of the aperture, and if this is eccentric, it will affect the processing performance and quality. It is well known that For this reason, the configuration is usually such that the coaxiality between the laser beam (1) and the nozzle OQ can be adjusted by moving the laser beam (1) or the nozzle portion.

[Problem to be solved by the invention]

However, even after adjustment, the optical axis of the laser beam (1) that enters the processing head body (2) may be affected by changes in the surrounding environment temperature of a laser transmitter (not shown) or a deflection mirror in the middle of the transmission optical path, or by the laser beam. There is a slight fluctuation due to thermal distortion due to absorption, and as mentioned above, the coaxiality of the laser beam (1) and the nozzle α0 is out of order, which sometimes results in defective machining.

Here, FIG. 4 shows the processing lens (4) and the deflection mirror αB.
shows a conceptual diagram of a rotary processing head of the type that rotates around the rotation axis @, and Fig. 5 shows the 18
It shows an attitude rotated by 0°. Such a type of laser processing head has recently been used in a three-dimensional laser processing machine that connects a plurality of rotating shafts and performs processing by three-dimensionally scanning a laser beam.

However, in the laser processing head as described above, for example, if the incident laser beam (1) is tilted by θran with respect to the rotation axis (2), the focal length of the processing lens (4) will be f when rotated by 180°. Then, the focal point (9) is 2, h
= 2fθ movement.

This means that the coaxiality of the focused laser beam at the nozzle opening (7) changes as described above, which of course often causes poor processing performance and processing quality. be.

However, in order to prevent this, the optical axis of the laser coating such as the nozzle must be adjusted many times.
There is one problem, such as the amount of time it takes to make adjustments.

This invention has been made to solve the above-mentioned problems, and can eliminate the adjustment work of the laser optical axis and nozzle part, and can greatly improve processing accuracy and processing quality. The purpose is to obtain a laser processing head.

[Means to solve the problem]

The laser processing head according to the present invention includes a processing lens that focuses a laser beam, a processing head body that movably supports the processing lens, and an opening at the tip that injects the focused laser beam and processing gas. a nozzle having a part;
a sensor provided at the tip of the nozzle to detect the injection position of the focused laser beam at the nozzle opening; and a controller that determines the movement position of the processing lens in accordance with a signal output from the sensor. , and a driving means for moving the processing lens in a direction perpendicular to the emission direction of the condensed laser beam in response to an output signal from the controller.

[For production]

In this invention, the drive means for moving the processing lens in a direction perpendicular to the beam emission direction is driven and controlled by a signal from a sensor provided at the nozzle opening and detecting the emission position of the condensed laser beam at the nozzle opening.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a cross-sectional view of the laser processing head, and Figure 2 is A--A in Figure 1.
This is a cross-sectional view taken along the line A, and in FIGS. 1 and 2, reference numerals (1) to 01 indicate the same or equivalent parts as those of the conventional device shown in FIG. 8, and explanations are omitted. (18a), (
18b) are first and second piezoelectric driving elements, one of which is in contact with the outside of the lens holder (3) and the other is embedded in the processing head body (2), and has the characteristic of expanding and contracting by voltage. . n4a) and (14b) are piezoelectric drive elements (1
8a), (18b), and one first and second compression coil spring, (15a),
(15b) C processing head main body (2) First and second thermal sensors whose tips protrude into the opening (7) provided in the nozzle α0, and the opening (7) of the nozzle αQ. ) A thermocouple is used that detects the emission position of the focused laser beam as heat and outputs a corresponding voltage signal. , C1G is a voltage drive element (18a) corresponding to the difference in voltage signals output from the respective heat sensitive sensors (15a) and (15b).

(18b) is an arithmetic controller into which a program for determining the amount of expansion/contraction is input.

Next, the operation will be explained. When the focused laser beam is emitted from the center of the opening (7) of the nozzle 00, the first and second thermal sensors (15a
The distances from -) and (151)) to the focused laser beam are all the same, and each heat sensor (15'3) is the same.
．． ).

(151)), the same one delayed pressure signal is input to the arithmetic controller (
Output to 1119. The arithmetic controller Qυ is inputted to the piezoelectric drive element f18'L, where there is no difference in the input Tcomical pressure signal and the same value.

(18b"l outputs a signal for the amount of expansion/contraction of 1 stem'. As a result, the piezoelectric drive element (I(a), flak)) Since it is configured to expand and contract, the above signal naturally does not cause expansion and contraction.However, the lens holder (3) also does not move, and the processed lens (4) is held in its original position. Note that if there is no difference in the voltage signals from the thermal sensors (15a,) and (15b), the arithmetic controller αυ
It may also be configured so that no signal is output.

Next, the focused laser beam is directed to the opening (7) of the nozzle αO.
) The injection position adjustment in the case of deviation from the center will be explained.

Now, for example, a focused laser beam is applied to the first thermal sensor (1
5'3. ) due to some disturbance, the distance and time at which the focused laser beam arrives from each thermal sensor (15a), (15b') will be different, so of course each thermal sensor (15a), (15b') will move in the direction of A difference also arises in the voltage signal output by 15b). The arithmetic controller αQ activates the piezoelectric drive element (18a) in advance according to the difference between the input voltage signals.
), (18b) in which the expansion/contraction amount is set is executed, and the signal thereof is output to the first piezoelectric drive element (1 block). As a result, the first piezoelectric driving element (L3a,) is extended to support the processed lens (4) and move the single lens holder (3) against the spring pressure of the first compression coil spring (14a). . As a result of ζ, the emission position of the focused laser beam at the aperture (7) is adjusted by a predetermined position t.

Note that the above shows the case of open-loop control, but closed-loop control (feedback system #J) may also be used. , arithmetic controller (16 piezoelectric drive element +
18a) may be controlled and driven.

By the way, although not shown, the thermal sensor is also provided with a pair of directions 9ζ perpendicular to the plane of the paper in FIG.
) is controlled and driven, and as a result, the focused laser beam emission position within the aperture plane is controlled to become the center of the nozzle QO opening (7).

In the above embodiment, the laser beam is shown as a coy+v-laser, but other lasers such as a YAG laser may be used, and it may be used not only for cutting processing but also for laser processing such as welding and heat treatment. The sensor that detects the emission position of the laser beam is the beam 1 depending on the wavelength of the laser used (for example, in the case of (I) 2, an infrared detection sensor)
Furthermore, the piezoelectric drive element for driving the processing lens (4) may be a general actuator such as an actuator.

Since the processing lens is configured to detect the injection position at the aperture and control the movement of the processing lens, there is no need to adjust the laser optical axis or nozzle part, and the position of the focused laser beam is always constant, allowing for easy processing. This has the effect of providing a laser processing head that can perform laser processing with improved accuracy and without causing processing defects.

[Brief explanation of the drawing]

@ Figure 1 is a configuration diagram of a laser processing head according to an embodiment of the present invention ζζ, Figure 2 is a sectional view taken along line A-A of the first cabinet, Figure 8 is a sectional view of a conventional laser processing head, and Figure 4. and FIG. 5 is an explanatory diagram of optical axis eccentricity in a conventional rotary processing head. In the figure, (1) is the laser beam, (2) is the processing head body, (3) is the lens holder, (4) is the processing lens, (6) is the processing gas inlet, (7) is the opening, and Ql is Nozzle, (18a) c1 c7) Piezoelectric drive element, (18
b) i is the second (7) piezoelectric drive element, (15a =) K 1 (D thermal sensor, (15b) is the @2 thermal sensor, and αG is the arithmetic controller. In the figure, the same Codes indicate the same or corresponding parts.

Claims (1)

[Claims] A processing lens that focuses a laser beam, a processing head body that movably supports this processing lens, a nozzle having an opening at its tip for ejecting the focused laser beam and processing gas, and the tip of this nozzle. a sensor for detecting the injection position of the condensed laser beam at the nozzle opening; a controller for determining the amount of movement of the processing lens according to a signal output from the sensor; A laser processing head characterized by comprising a drive means for moving a processing lens in a direction perpendicular to the emission direction of a condensed laser beam in response to an output signal.