JPH11197866A - Device for laser beam machining and laser beam cutting method for work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out an excellent cutting by keeping a posture angle of laser beam machining head to a work at a proper angle without resort to robot teaching through manual operation at the time of laser beam cutting of a cylindrical vessel body or others as an object of work. SOLUTION: In a laser beam machining device for cutting work by projecting laser beam outputted from a laser generator, a laser beam machining head 2 is mounted on an articulated robot 1, and by operating the robot the matching head is made to scan along a cutting route according to a teaching. In this case, a servo-mechanism 16 which automatically adjusts a posture angle ψof the machining head with respect to the work 6 to a prescribed angle is provided; concretely, an angle regulator 10 is mounted on the robot 1, and at the same time, as a posture angel detecting element of the machining head 2 a distance sensor 11 is mounted on the machining head 2 to measure the distance to the work 6, the sloped angle ψ is calculated based on a measuring signal of the distance sensor 11 using the cosine law of trigonometry, and then automatic adjustment is executed following the set angle given to an angle setting unit 14.

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 suitable for cutting metal products, in particular, for cutting a cylindrical container into small pieces and disassembling the same, and a laser cutting method for the work.

[0002]

2. Description of the Related Art FIG. 6 shows the general construction of a conventional laser processing machine for cutting. In the figure,
Reference numeral 1 denotes an articulated robot, 1a denotes a robot controller, 2 denotes a laser processing head generally called a "torch" attached to the end of an arm of the robot 1 via a linearly movable actuator 3, 4 denotes an optical fiber 5 to a processing head 2. A laser oscillator (a high-output laser oscillator such as YAG or CO ₂ ) connected via a wire, 6 is a workpiece to be cut, and 7 is a capacitance-type height sensor provided at the tip of a nozzle of the processing head 2. .

Here, the robot 1 uses a playback robot that performs work in accordance with cutting route information that has been taught in advance. In addition, the laser processing head 2
Denotes a laser beam output from the laser oscillator 4, which focuses the laser beam from the laser oscillator 4 into a spot and irradiates the surface of the work 6 with an assist gas (not shown). So that it gushes toward Further, a distance (stand-off) h between the nozzle tip of the processing head 2 and the work 6 during laser processing by an automatic stand-off control system including the actuator 3, the height sensor 7, the control unit 8, and the driver 9 of the actuator 3. At a constant distance of about 1 mm.

When the work 6 is to be cut, the robot controller 1a is first switched to the manual mode, and then the machining head 2 is manually operated to teach the work 6 along the cutting route designated on the work 6. The route is programmed and stored in the robot controller 1a. Next, when actually cutting the workpiece 6 with the laser, the robot controller 1a is switched to the automatic mode, and the laser beam is emitted from the laser oscillator 4 while scanning the processing head 2 along the cutting route specified in the previous teaching. The surface of the work 6 is irradiated with a laser beam through the processing head 2 and, at the same time, is cut by blowing an assist gas. The principle of laser cutting is well known, and the description is omitted here.

On the other hand, when radioactive waste generated in a nuclear reactor facility or the like, in particular, a cylindrical container made of metal such as stainless steel (for example, a plate having a thickness of 4 mm, a diameter of about 700 mm, and a height of 900 mm) is to be stored for a long time in a predetermined storage place, In order to save storage space, cylindrical containers, which are waste materials, are subdivided and dismantled.
It is necessary to reduce the volume. Specifically, after cutting the lid and the bottom plate from the body of the cylindrical container, the body is finely cut into rectangular short pieces. It shall be housed in a cylindrical container at once,
Applying the laser beam machine to the dismantling work is being studied.

FIG. 7 is an explanatory view of an operation of laser cutting a rectangular short piece from the body (work 6) of the cylindrical container using a laser processing machine. It is represented by dotted lines (virtual lines) in the vertical and circumferential directions. Then, when performing the laser cutting operation, the laser processing head 2 is accessed from the side while the body of the cylindrical container is suspended, and the cutting along the contour is performed along each of the cells along the cutting point. After teaching the route, the machining head 2 is scanned in the vertical and circumferential directions while irradiating a laser beam along the cutting route by a robot operation to cut a rectangular short piece. 6a is a cut piece and 6b is a cut piece 6.
It is a hole opened at the mark where a was cut.

[0007]

As described above, when a rectangular cylindrical piece is cut and dismantled from the body of a metal cylindrical container as a work by using the above-mentioned laser processing machine, the following steps are taken. There are problems to be noted. That is, (1) When teaching the cutting route along the peripheral surface of the cylindrical container to the robot, as shown in FIG. The three points A, B, and C of the point are input, and the robot controller calculates an arc trajectory passing through the points A, B, and C to program it.

In this case, teaching at a position for determining each point along the linear cutting route is easy, but the posture angle ψ of the processing head 2 with respect to the peripheral surface of the cylindrical container (at each point A, B, C). Vertical line passing through the center O and the processing head 2
The relative angle with respect to the optical axis (center axis) varies considerably due to visual observation and manual operation at each point. For example, as shown by a broken line at point C in FIG. ψ may be large.

On the other hand, the cutting performance when laser cutting metal products is affected by the attitude angle ψ of the processing head 2. With respect to this point, an experiment of laser cutting a stainless steel plate having a thickness of 4 mm (with the moving speed of the processing head 2 constant) was performed, and the following results were obtained. That is, FIG.
X, Y, Z starting from the cutting point of the work 6 as represented by
In the axis coordinate system, the attitude angle of the processing head 2 with respect to the cutting progress direction P is ψ (the angle in the Y axis direction with respect to the Z axis), and the attitude angle in the direction perpendicular to the cutting progress direction P is θ (in the X axis direction with respect to the Z axis). Angle), the attitude angle of the processing head 2 is −10 ° <
切断 <50 °, −20 ° <θ <20 °, the cutting was successfully performed.
If the angle is larger than this, the cutting is poor (the cut surface becomes grooving due to dross adhesion etc. and it cannot be cut completely)
Occurs.

(2) As described with reference to FIG. 7, when the rectangular cut piece 6a cut from the body of the metal cylindrical container is separated from the body, an arc-shaped piece as shown in FIG. Cutting piece 6
A phenomenon occurs in which a springs back and deforms so as to spread from the broken line to the shape represented by the real gland. Therefore, the posture angle θ 角度 0 ° of the processing head 2 in FIG.
When the optical axis is oriented in the direction of the center of the cylindrical body, the kerf width (cut groove width) for laser cutting is 1 mm.
From the following, the left and right cut surfaces of the cut piece 6a spring-backed after cutting are caught on the inner surface of the hole 6b opened on the trunk side as indicated by point Q in the drawing, and do not separate outwardly. Disturbs the dismantling procedure.

The present invention has been made in view of the above points, and a first object of the present invention is to always adjust the attitude angle of a laser processing head with respect to a work when performing laser cutting on the body of a cylindrical container or the like. A second object is to provide a laser processing apparatus provided with a posture angle adjusting means for a processing head capable of performing good cutting while maintaining an appropriate angle, and a second object is to cut a circular arc-shaped cut piece cut from a body of a cylindrical container. An object of the present invention is to provide a laser cutting method of a work which can be surely separated from a body.

[0012]

According to the present invention, there is provided a laser processing apparatus for irradiating a workpiece with a laser beam output from a laser oscillator and irradiating the workpiece with a laser beam. The work head is mounted on an articulated robot, and the robot is operated so that the distance between the nozzle tip of the work head and the work is kept constant, and the work head is scanned along the cutting route pre-teached. Equipped with a servo mechanism that automatically adjusts the attitude angle of the processing head with respect to the processing surface of the workpiece according to a specified angle given from the outside (claim 1)
Specifically, the servo mechanism is configured as follows.

(1) An actuator for the servo mechanism is equipped with an angle adjuster for the processing head at the tip of the robot, and a distance for measuring the distance between the outer surface of the processing head and the surface of the work is used as an attitude angle detecting element for the processing head. Attach a sensor, calculate the inclination angle of the machining head with respect to a perpendicular line set at the machining point of the workpiece using the second law of cosine of the triangle based on the output signal of the distance sensor, and use the angle adjuster with an error signal from the set angle. Is driven (claim 2).

(2) In the above item (1), in order to increase the measurement accuracy of the inclination angle, distance sensors are installed at two positions on the outer periphery of the processing head with the processing head interposed therebetween, and the processing head is determined from the difference between the measured values. The angle of inclination is calculated so as to be accurately obtained (claim 3). As described above, by equipping the servo mechanism for adjusting the attitude angle of the processing head, it is not necessary to manually teach the robot the attitude angle of the processing head with respect to the workpiece for each point on each cutting route by visual manual operation. By simply inputting a numerical value in advance, during laser cutting, the attitude angle of the processing head can be automatically controlled to follow the set angle, so that the attitude angle of the processing head on the cutting route is always set to the appropriate angle. Good work cutting can be performed while maintaining

According to the present invention, in order to achieve a second object, when the body of a metal cylindrical container is cut into rectangular short pieces and disassembled using the laser processing apparatus,
Along the cutting route in the vertical direction, the attitude angle of the laser processing head is inclined to the outside of the cut piece in a direction perpendicular to the cutting progress direction so as to cut the short piece from the trunk.

According to this laser cutting method, even if a rectangular cut piece cut from the body of a metal cylindrical container is deformed so as to spring back and expand right and left immediately after cutting, the inner surface of the cut mark hole is formed. Separate without getting caught on the outside. In this case, the posture angle of the machining head may be about 10 °, and the setting of this angle can be simply performed by inputting the posture angle to the angle setting device of the servo mechanism without relying on manual teaching. Can be set to

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a laser processing apparatus according to the present invention will be described below with reference to the embodiments shown in FIGS. 1, 2, 3 and 4. FIG. In the drawings of each embodiment, the same members corresponding to FIGS. 6 to 10 are denoted by the same reference numerals. [Embodiment 1] FIGS. 1 and 2 show an embodiment corresponding to claims 1 and 2 of the present invention. That is, in this embodiment, as compared with the conventional laser processing machine shown in FIG. 6, a servo mechanism for automatically adjusting the attitude angle of the processing head 2 with respect to the processing surface of the work 6 in accordance with a specified angle given from the outside. 16 are equipped.

The servo mechanism 16 includes an attitude angle adjuster (actuator) 1 attached to the end of the arm of the robot 1.
0 and a distance sensor (posture angle detecting element) that is attached to the outer periphery of the processing head 2 to measure the distance between the workpiece 6 and the surface of the work 6
11 and a feedback control system including an arithmetic unit 12, a comparator 13, an angle setting unit 14, and an angle controller 15.

Here, the attitude angle adjuster 10 moves the actuator 3 to which the processing head 2 is attached in the direction of the arrow along the arc-shaped rail centering on the tip point of the processing head 2 (the laser irradiation point of the work 6). This is a servomotor that moves and changes the attitude angle of the processing head with respect to the work 6. The distance sensor 11 is a laser displacement meter, an ultrasonic displacement meter, or a contact displacement meter (measurement distance: 100 to 200).
mm), and is attached to the side surface of the case of the processing head 2 with the detection end facing forward (one of the front and rear sides with respect to the moving direction of the attitude angle adjuster 10).

Next, a method of detecting the attitude angle of the machining head 2 with respect to the workpiece 6 by the servo mechanism 17 will be described with reference to FIG.
This will be described below. In FIG. 2, the laser irradiation point on the work 6 facing the processing head 2 is D, the distance sensor 1
The mounting point of No. 1 is E and the measuring point of the distance sensor 11 is F. In a triangle DEF formed by connecting points D, E, and F, the distance between DE and L is L (fixed value), the distance between EF is l _S (measured value of the distance sensor),
The distance between the D-F l _X, the apex angle ∠DEF β (fixed value) of the E, the apex angle of D and alpha _X. Further, assuming that the angle between the center line O ′ of the processing head 2 and the line DE is γ (fixed value), the unknown angle α _X can be calculated as follows using the second law of cosine of a triangle. You can ask.

[0021]

## EQU1 ## l _X = (l _S ² + L ² −2l _S L cosβ) ^1/2 (1)

[0022]

## EQU2 ## l _S = (l _X ² + L ² -2l _X L cosα _X ) ^1/2 ........................ (2)

[0023]

Α _x = cos ^-1 ｛(L ² + l _X ² -l _S ² ) / 2Ll _X ｝ ^1/2 (3) Also, the inclination angle of the machining head 2 at the point D ψ (D
The angle formed between the perpendicular set at the point and the center line O ′ of the machining head 2) is expressed by 90 ° − (γ + α _X ).

[0024]

４ = 90 ° − [γ + cos ⁻¹ ｛(L ² + l _X ² −l _S ² ) / 2Ll _X ｝ ^1/2 ] (4) Here, the angle γ and the distance L are fixed. The value, the distance l _S, can be calculated by the distance sensor 10, and the distance l _X can be calculated from the above equation (1).

Therefore, the distance sensor 11 shown in FIG.
Is input to the calculator 12, the inclination angle ψ obtained by the calculation is compared with the set angle given to the angle setter 14 by the comparator 13, and the error signal is sent to the angle controller 15. By outputting, the angle controller 15 drives the angle adjuster 10 as an actuator so that the attitude angle of the processing head 2 approaches the above-mentioned set angle.

With this arrangement, an appropriate inclination angle can be set by the angle setting device 12 without manually teaching the posture angle of the machining head 2 at each of the teaching points A, B, and C in FIG. For example, at the time of cutting, the posture angle of the processing head 2 is automatically adjusted (feedback control) so as to follow the set angle, and as a result, good laser cutting can be performed.

Although the work 6 is flat in FIG. 2,
Even when the workpiece 6 has an arc shape, if the radius of curvature is sufficiently large compared to the radius of the processing head 2, the inclination angle の of the processing head 2 can be calculated by calculation with almost no angular error. [Embodiment 2] FIGS. 3 and 4 show an embodiment corresponding to claims 1 and 3 of the present invention. That is, when the work 6 has an arc shape like a cylindrical container and the radius of curvature is not sufficiently large as compared with the radius of the laser processing head 2, the configuration of the first embodiment (the distance sensor 11) is used. Is one), the detection accuracy of the attitude angle of the processing head 2 is low. In this embodiment, this point is improved. In the servo mechanism 16 shown in FIG. 3, two laser processing heads 2 are provided on the front and rear sides (front and rear with respect to the cutting progress direction) of the main body case with respect to the laser processing head 2. The distance sensors 11A and 11B are provided. Further, the computing units 12A and 12B are combined for each of the distance sensors 11A and 11B, and the comparator 17 and the second computing unit 18 are additionally provided at the subsequent stage. ,
The output of the arithmetic unit 18 and the set angle of the angle setting unit 14 are compared by the comparator 13 as in the first embodiment, and the error signal is input to the angle controller 15 to drive the angle adjuster 10. ing.

Next, a method of calculating the inclination angle of the processing head 2 with the configuration of FIG. 3 will be described with reference to FIG. In FIG. 3, D is a laser irradiation point on the work 6 facing the processing head 2, E and G are attachment points to the distance sensors 11A and 11B, and F and H are measurement points of the distance sensors 11A and 11B. In the triangle DEF and the triangle DGH formed by connecting the above points,
The distance between DE, DG is L (fixed value), EF, G-
The distance between H is l _1S , l _2S (measured value of the distance sensor), and the distance between DF and DH is l _1X , l _2X , respectively.
The vertex angles ∠DEF, ∠DGH of E and G are β (fixed values), and the vertex angles of D are α _1X and α _2X , respectively. Further, the angle between the center line O ′ of the processing head 2 and the lines DE and DG is represented by γ.
Then, the unknown angles α _1X and α _2X can be obtained as follows using the second law of cosine of the triangle, as in the first embodiment. That is,

[0029]

Α _1X = cos ^-1 ｛(L ² + l _1X ² -l _1S ² ) / 2Ll _1X ｝ ^1/2 ... (5)

[0030]

Α _2X = cos ⁻¹ ｛(L ² + l _2X ² −l _2S ² ) / 2Ll _2X ｝ ^1/2 (6) Here, the inclination angle of the processing head 2 at the point Dψ
(The angle between the perpendicular line at the point D and the center line O 'of the processing head 2) is obtained by the following equation.

[0031]

７ = (α _1X −α _2X ) / 2 = [cos ⁻¹ ｛(L ² + l _1X ² −l _1S ² ) / ² Ll _1X ｝ ^1/2 − cos ⁻¹ ｛(L ² + l _2X ² −l _2S ² ) / ² Ll _2X ｝ ^1/2 ] / 2 (7) And, in the servo mechanism of FIG. 3, the distance sensors 11A, 1
1B, the computing units 12A and 12B are connected to the angles α _1X ,
α _2X is calculated and calculated, and α _1X and α output from the comparator 17 are calculated.
The difference from _2X is divided by “2” by the calculator 18 to calculate the inclination angle ψ. The subsequent circuit configuration is the same as that of the first embodiment. The output of the arithmetic unit 18 and the set angle input to the angle setting unit 14 are compared by the comparator 13, and the error signal is output to the angle controller 15 and The angle adjuster 10 is driven. Thus, the tracking control is performed so that the attitude angle の of the processing head 2 approaches the set angle given from the outside.

In this embodiment, even when the radius of curvature of the work 6 is small, such as the body of a small cylindrical container, the attitude angle ψ of the laser processing head 2 with respect to the work 6 is accurately detected and appropriate follow-up control is performed. be able to. Next, a laser cutting method for a workpiece according to claim 4 of the present invention will be described. That is, as described above with reference to FIG. 7, when a rectangular short piece is laser-cut from the body of a metal cylindrical container using a laser processing machine, the posture angle of the laser processing head 2 is taken along the vertical cutting route. θ (corresponding to the tilt angle θ in the X-axis direction shown in FIG. 9) is slightly inclined outward with respect to the cutting piece 6a, and in this state, the work 6 is laser-cut along the vertical cutting route. .

FIG. 5 shows a state in which a rectangular short piece is laser-cut from the body (work 6) of the cylindrical container by the above-mentioned laser cutting method (in comparison with the conventional laser cutting method shown in FIG. 10). Even if the arc-shaped cut piece 6a separated from the trunk immediately after cutting is spring-backed to a shape represented by a solid gland from the broken line, the cut surfaces at the left and right ends of the cut piece 6a It is possible to smoothly separate outwardly without being caught on the inner surface of the hole 6b of the cutting mark opened on the part side.

If the inclination angle θ of the processing head 2 in this laser cutting step is about 10 °, there is no risk of catching the cut piece 6a due to spring back, and the angle is set in the first embodiment. , 2 can be easily set without relying on visual teaching by manual operation, and during laser cutting, the machining head 2 can be set along the vertical cutting route. The posture angle θ can be automatically adjusted according to the set angle.

[0035]

As described above, according to the laser cutting apparatus of the present invention, the servo mechanism for automatically adjusting the attitude angle of the processing head with respect to the processing surface of the work to the specified angle given from the outside is provided. By doing so, the following effects can be obtained. That is, when teaching a cutting route to a robot such as a cylindrical container having a cut processing surface having an arc surface or a curved surface, the posture angle of the laser processing head with respect to the processing surface of the work is visually determined. Instead of relying on manual operation, just by setting an appropriate attitude angle with the servo mechanism, it is possible to adjust the attitude angle of the laser processing head properly and automatically during laser cutting, which causes cutting failure. And excellent laser cutting can be performed without any problem.

When the body of the cylindrical container is cut into short rectangular pieces by using the laser processing apparatus according to the present invention, the posture angle of the laser processing head is cut along the vertical cutting route. By cutting the short piece from the torso by inclining outwardly of the cut piece in a direction perpendicular to the direction, even if the arc-shaped cut piece cut off from the body immediately after cutting is deformed so that it springs back and spreads The left and right cut surfaces of the cut pieces are pulled out to the outside without being caught on the inner surface of the hole of the cut mark opened on the body side, and are separated smoothly, thereby facilitating the dismantling work of the cylindrical container. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a servo mechanism for adjusting an attitude angle of a laser processing head corresponding to a first embodiment of the present invention, and a control system thereof.

FIG. 2 is an explanatory diagram of a calculation method for obtaining the attitude angle of the laser processing head using the second law of cosine of the triangle in the configuration of FIG. 1;

FIG. 3 is a diagram showing a configuration of a servo mechanism for adjusting an attitude angle with respect to a laser processing head according to a second embodiment of the present invention, and a control system thereof.

FIG. 4 is an explanatory diagram of a method of calculating a posture angle of a laser processing head with the configuration of FIG. 3;

FIG. 5 is an explanatory diagram of a laser cutting method for a workpiece according to a third embodiment of the present invention.

FIG. 6 is an overall configuration diagram of a conventional laser beam machine.

FIG. 7 is an explanatory view of a process when laser cutting a rectangular short piece from the body of a cylindrical container using the laser processing machine of FIG. 6;

8 is an explanatory diagram of a teaching method by manual operation of the robot in FIG. 7;

FIG. 9 is a schematic diagram showing a posture angle of a processing head with respect to a traveling direction of laser cutting.

FIG. 10 is an explanatory view of a trouble situation in which a cut piece laser-cut from the body of the cylindrical container in FIG. 7 is caught on the body by deformation due to springback;

[Explanation of symbols]

 Reference Signs List 1 articulated robot 2 laser processing head 4 laser oscillator 6 work 6a cut piece 7 height sensor 10 attitude angle adjuster (actuator) 11, 11A, 11B distance sensor ψ, θ

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B25J 17/02 B25J 17/02 A // B23K 101: 12

Claims (4)

[Claims] A laser processing apparatus for irradiating a workpiece with a laser beam output from a laser oscillator and cutting the workpiece, wherein a processing head for irradiating a laser beam is attached to an articulated robot, and a nozzle tip of the processing head is operated by the robot. While maintaining the distance to the work constant, the processing head is scanned along the cutting route pre-teached, and the posture angle of the processing head with respect to the work surface of the work is adjusted to the specified angle given from the outside. A laser processing device equipped with a servo mechanism for automatically adjusting. 2. A laser processing apparatus according to claim 1, wherein
The actuator of the servo mechanism is equipped with an angle adjuster for the processing head at the tip of the robot, and a distance sensor that measures the distance between the workpiece surface and the outer periphery of the processing head is attached as a posture angle detection element for the processing head. Based on the output signal of the sensor, the inclination angle of the machining head with respect to the vertical line at the machining point of the work is calculated using the second law of cosine of a triangle, and the angle adjuster is driven with an error signal from the set angle. A laser processing apparatus characterized by the above-mentioned. 3. A laser processing apparatus according to claim 2, wherein
The distance sensor is placed between the front and rear 2
A laser processing device which is installed at a location. 4. When the body of a metal cylindrical container is cut into small rectangular pieces and disassembled by using the laser processing apparatus according to claim 1, laser processing is performed along a vertical cutting route. A laser cutting method for a work, wherein a short piece is cut from a body by tilting a posture angle of a head outwardly of a cut piece in a direction perpendicular to a cutting progress direction.