JPH03193290A - Laser beam machine and laser beam machining method - Google Patents

Abstract

PURPOSE:To greatly improve the accuracy of locus in machining of a fine shape by providing a rotative mechanism to rotate a reflection mirror farthest from a oscillator side round the optical axis entering the reflection mirror and a moving mechanism to move the mirror in the axial direction of the optical axis. CONSTITUTION:The laser beam 9 reflected finally by the reflection mirror 8 is condensed by a condenser 7. A material 6 to be worked irradiated by high energetic density beam reacts immediately to do laser beam machining. A betadrive shaft and an incidence optical axis is meet each other on the reflection mirror 8, the reflected laser beam 9 rotates in accordance with the rotational angle of the beta shaft, passes through the center of the lens and is outgone from the center of a machining head 1. A condensing lens 7 too rotates in a body with the reflection mirror 8 and moves the focus of the laser beam 9 in a direction Y. The reflection mirror 8 has the moving mechanism to be moved by an axis A in the direction parallel to the optical axis and the focus F1 of the laser beam is moved in the direction Y. The focus F1 of the laser beam 9 can be moved by the A axis and the beta shaft on a plane XY. In this way, great improvement of locus accuracy can be expected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser processing machine and a laser processing method for cutting, welding, etc., and relates to a laser processing machine equipped with a processing head for fine processing and a method for controlling this processing head. The present invention relates to a laser processing method for performing laser processing.

[Conventional technology]

In recent years, the application fields of laser processing have become increasingly diverse.
Laser processing machines themselves are also required to be more flexible and at the same time have precision processing performance.

Three-dimensional laser processing machines and laser robots are expected to meet these needs.

In particular, laser robots are an extremely flexible production processing tool, and can produce high-power laser beams of various shapes and shapes, which previously could only be used in the bed of a laser processing machine without making special jigs. It is possible to irradiate and process large-sized workpieces.

[Problem to be solved by the invention]

However, in order to increase the flexibility of such three-dimensional laser processing machines and laser robots, the rigidity of the mechanism tends to decrease, and the response speed of the servo system generally tends to be slow. .

In addition, in order to machine a workpiece into a certain shape, the path to be machined and the posture of the machining head are programmed and reproduced in advance, but the commands issued to the motors of each drive shaft are based on the programmed path and posture. It is calculated and sent from These commands should include acceleration/deceleration times in advance to avoid stressing the mechanism.

In this way, machining is performed while all axes are synchronized. In such a system, all axes are controlled simultaneously to interpolate the path, so the interpolation distance is slow, and the acceleration/deceleration time is set long so as not to burden the large machine body.

Furthermore, the mechanism is kinematically complex, and the calculation time for linear and circular interpolation increases compared to a processing machine configured with a simple orthogonal coordinate system.

As a result, in these radar robots, for example, φ5
It is extremely difficult to process minute shapes such as circles with a size smaller than 0 with high precision. Furthermore, in laser machining, machining speed control is important, and in conventional systems, when machining is attempted at high speed, trajectory controllability usually deteriorates dramatically depending on the speed.

The present invention has been made in view of these points, and an object of the present invention is to provide a laser processing machine equipped with a processing head for processing minute shapes.

Another object of the present invention is to provide a laser processing method for processing minute shapes using this processing head.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a laser processing machine that introduces a laser beam using a reflecting mirror and focuses the laser beam to perform laser processing. A laser beam processing machine is provided, which includes a rotation mechanism that rotates a mirror around an optical axis that enters the reflecting mirror, and a movement mechanism that moves a mirror in the axial direction of the optical axis.

In addition, in a laser processing method in which a laser beam is introduced using a reflecting mirror and condensed to perform laser processing, the reflecting mirror farthest from the oscillator side is rotated around the optical axis that enters the reflecting mirror, and the optical axis is rotated. The laser beam is moved in the axial direction of the
Provided is a laser processing method characterized by processing a workpiece by following a dimensional trajectory.

[Effect]

For example, a rotating mechanism that rotates a reflecting mirror around an optical axis and a moving mechanism that can move in the direction of the optical axis are provided at the tip of an arm of a laser robot, and these are controlled by a robot controller.

The optical axis direction is set as the X axis, and the laser beam is moved in the Y direction by a shaft rotating around the optical axis.

Thereby, the laser beam can be moved in the XY force directions, and a fine shape on a plane can be followed at high speed to perform laser processing.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a diagram illustrating the operation of the processing head of the laser processing machine of the present invention. The laser beam 9 which has been finally turned back by the reflecting mirror 8 is condensed by the condensing lens 7. The workpiece 6 irradiated with the high energy density beam immediately evaporates.
Laser processing is performed after melting and combining. In the reflecting mirror 8 in FIG. 1, the β drive axis and the incident optical axis coincide, and the reflected beam 9 rotates according to the rotation angle of the β axis and always passes through the center of the lens and reaches the processing head. is emitted from the center of The condensing lens 7 also rotates together with the reflecting mirror 8 to move the focal point F1 of the laser beam 9 in the Y direction. The distance l between the reflecting mirror 8 and the focal point F1 of the laser beam needs to be large enough to prevent the gap between the focal point F1 and the workpiece from increasing due to the rotation of the β axis.

Furthermore, the reflecting mirror 8 is equipped with a moving mechanism that moves in a direction parallel to the optical axis by the A-axis, and the focal point F1 of the laser beam is
Move in the Y direction.

Therefore, the focal point F1 of the laser beam 9 can be moved on the XY plane by the A axis and the β axis.

FIG. 2 is an overall configuration diagram of a laser processing machine according to the present invention. A laser beam emitted from the laser oscillator 3 is introduced into the laser robot 2 through the light guide path 5, is reflected several times by a reflecting mirror in the laser robot 2, and is guided to the processing head 1. The laser robot and laser oscillator 3 are controlled by a robot control device 4. The workpiece 6 is irradiated with laser light from the processing head 1, and laser processing is performed.

3(a) and 3(b) are diagrams schematically showing the positional relationship around the processing head. b) is a view seen from a direction parallel to the optical axis.

In advance, the attitude of the processing head 1 is controlled so that it is perpendicular to the center of the area where micromachining is to be performed on the surface of the workpiece 6, the gap between the tip of the processing head 1 and the workpiece 6 is adjusted, and the focal point is adjusted. Align Fl with the surface of the workpiece 6. Workpiece 6
has a shape close to a flat surface. Here, consider three-dimensional coordinates on the surface of the workpiece 6 such that the Z axis is in the direction of the processing head 1.

First, the processing head 1 can be moved in parallel in the direction of the A-axis, and when this is taken as the X-axis, a coordinate system is determined by placing the Y-axis orthogonal to the x1Z-axis on the workpiece. Next, the processing head 1 rotates around the β-axis. Let the rotation angle be φ, the distance between the β-axis and the workpiece be l, and consider the point at which the tip of the processing head 1 drops onto the xY plane. and y=β*sinφ −−−−−−・−(1) When φ is small, the calculation time may be further shortened using the following equation.

y=l*φ ・ (2) On the other hand, if the moving distance of the A-axis is a, then x = a ------(3), and on the surface of the workpiece 6, the β-axis is limited to the vicinity of this coordinate. , interpolation can be performed using only two axes, the A-axis.

(x, y) = (a, Il* sinφ)(
4) In other words, the commanded (x, y) is sent to the robot controller 4.
The amount of movement or rotation of the above A-axis and β-axis (B,
1*sinφ) and operate the A-axis and β-axis.

In laser processing, the position of the focal point with respect to the workpiece has an important meaning. FIG. 4 is a diagram showing details of the surface of the workpiece. That is, by moving the β axis, the focus F1
is shifted by 2 with respect to the processing point P1. This value is z=ji'* (1-cosφ) (5).

If the allowable range of deviation of the focal position for the workpiece in laser processing is ±δ, then δ is the output of the laser oscillator, the transverse mode, the beam diameter, the focal length of the condenser, the material of the workpiece,
It varies greatly depending on processing conditions such as thickness. Of course, as long as 1z1×δ·---(6) is satisfied, processing can be performed without any problem. (5), (6
) From the formula, the range ±Φ of φ is limited by Φ= arccos (1-δ/l) − (7).

Further, the optical axis 9 of the laser beam enters the workpiece 6 at an angle of φ. Although it depends on the processing conditions, laser processing generally allows processing even if this angle exceeds 10''.

Since φ is limited to a small value due to the restriction of equation (7), it does not pose a practical problem.

Find the movable range of y ±Y from equation (7). From equation (1), Y=j! *sinΦ (8) Figure 5 is a graph showing the deviation of the focal point position under certain processing conditions. In the figure, the horizontal axis is the cutting width of the workpiece, and the vertical axis is the focal position shift δ. That is, as the focal position shift increases, the cutting width d also increases, the roughness of the cut surface begins to decrease at point Pa, and dross begins to adhere at point Pb. Therefore, for practical machining, the deviation of the focus position is ±
The range is about 1 mm. Therefore, when δ=l mm f=400mm, Φ=0. 0707 rad Y=28.27 mm, and if the movable range of the A axis is set to X=28 mm, a rectangular range of 56 x 56 mm can be covered. In this case, if formula (2) is used, the maximum is 0.02
This results in an error of only 4 mm.

From the above, for a flat workpiece, 56X5B
In the range within mm, only the two axes, β-axis and A-axis, are interpolated and controlled in orthogonal coordinates or a space close to orthogonal coordinates, and there is no need to move other axes, so there are fewer calculations required for interpolation.
In addition, since only the two axes at the tip of the machine are moved, the servo system can be moved quickly, and trajectory accuracy can be improved without reducing machining speed.

FIGS. 6(a) and 6(b) are external views of a laser robot equipped with the present invention. FIG. 6(b) is a side view of FIG. 6(a). The laser beam transmitted from the oscillator 3 passes through the light guide path 5, is guided to the processing head 1 through the light guide path 14 by reflectors 13a and 13b, etc., is focused, is output from the nozzle 15, and is laser processed. I do. The processing head 1 is controlled in any position and in any posture along five axes, θ, W, U, r, and β, so that the laser beam can be incident perpendicularly onto the workpiece. An A-axis is added to the machining blade 1 in order to carry out the present invention.

FIG. 7 is a diagram showing a first embodiment of the processing head. The reflecting mirror 8 and lens 7 in FIG. 1 correspond to the reflecting mirror 21 and lens 23 in FIG.

The laser beam 25 is irradiated through the nozzle 33,
The distance between the nozzle tip and the workpiece is usually between 0.5 mm and 5 mm depending on the processing purpose. Although the entire processing head 1 rotates around the β-axis and moves in the direction of the arrow by the A-axis, the laser beam 25 always passes through the center of the nozzle 33.

Next, the detailed mechanism of the processing head will be described.

In Fig. 7, 21 is a reflecting mirror, 22 is a reflection angle adjustment mechanism, and 23
is a condensing lens. A laser beam 25 entering the oscillator 3 along the β axis is reflected by a reflecting mirror 22, condensed by a condensing lens 23, and focused 26 on the workpiece 6.
Laser cutting is performed at focal point 26. The processing head 1 including the reflecting mirror 21 includes a spline nut 28a, a spline shaft 28b, a ball nut 29a, and a ball screw 29b.
When the shaft 30 is rotated by a servo motor or the like, it rotates around the β axis.

Furthermore, when the shaft 31 is rotated, it moves linearly in the A-axis direction. The servo motor and the pulse coder attached thereto are simultaneously controlled by the robot control device 4. Reference numeral 32 denotes a piping for supplying auxiliary gas, and the auxiliary gas introduced therefrom is supplied to the processing point and assists the laser processing.

To carry out fine machining, first, keep the RAD 1 perpendicular to the workpiece near the center of the area to be machined.
Position at the correct distance.・Next, fix the axes other than the β-axis and the A-axis to enter the micro-machining mode. Simultaneous control of only the β-axis and A-axis enables high-speed laser processing with high trajectory accuracy. After returning to the position when micromachining was started, simultaneous control of all axes except the A-axis is resumed.

FIG. 8 is a diagram showing a locus of a circle processed by the laser processing machine of the present invention. That is, it is a diagram processed only with the A-axis.

FIG. 9 is a diagram showing a trajectory of machining performed by controlling five axes of a laser robot without a machining head.

Comparing the two, we see a significant improvement in trajectory accuracy.

FIG. 10 is a diagram showing a second embodiment of the processing head.

Here, the reflecting mirror 21 in FIG. 7 is replaced with a parabolic mirror 41, and the condensing lens 23 becomes unnecessary.

This machining head can also be expected to improve trajectory accuracy based on the same principle as the machining head shown in FIG. Symbols in other figures are number 7
Since it is the same as the figure, it is omitted.

〔Effect of the invention〕

As explained above, the present invention can be expected to significantly improve trajectory accuracy in processing fine shapes. In particular, according to the present invention, even if a new device is added to improve trajectory accuracy, there is no need to increase the number of reflecting mirrors, resulting in a simple configuration.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the operation of the processing head of the laser processing machine of the present invention, Fig. 2 is an overall configuration diagram of the laser processing machine according to the invention, and Fig. 3 (a) and (b) are the surroundings of the processing head. Figure 4 is a diagram showing the details of the surface of the workpiece, Figure 5 is a graph showing the deviation of the focal position under certain processing conditions, Figure 6 (a) and ( b) is an external view of a laser robot equipped with the present invention; FIG. 7 is a diagram showing the second embodiment of the processing head; FIG. 8 is a diagram showing the locus of a circle processed by the laser processing machine of the present invention; FIG. 9 is a diagram showing a trajectory of machining performed by controlling five axes of a laser robot without a machining head, and FIG. 10 is a diagram showing a second embodiment of the machining head. Laser robot for processing --- Laser oscillator --- Robot controller Light guide path Workpiece Condensing lens Reflector

Claims (5)

[Claims] (1) In a laser processing machine that introduces a laser beam using a reflector and focuses it for laser processing, a rotation mechanism that rotates the reflector farthest from the oscillator around the optical axis that enters the reflector. and a moving mechanism for moving in the axial direction of the optical axis. (2) The laser processing machine according to claim 1, wherein the reflecting mirror is a parabolic mirror and also serves as a condensing device. (3) The laser processing machine according to claim 1, characterized in that the rotating mechanism and the moving mechanism are configured to be able to be controlled simultaneously. (4) The laser processing machine according to claim 1, wherein the rotation mechanism and the movement mechanism are provided at the tip of an arm of a robot. (5) In a laser processing method in which a laser beam is introduced using a reflecting mirror and focused to perform laser processing, the reflecting mirror farthest from the oscillator side is rotated around the optical axis that enters the reflecting mirror, and the Move the laser beam in the axial direction of the optical axis to
A laser processing method characterized by processing a workpiece by following a dimensional trajectory.