JPH07236985A - Laser cutting method and device - Google Patents

Abstract

PURPOSE:To prevent the turbulence of streaks or melting down causing on a cutting surface of a work to be cut and improve the quality of work to be cut by applying a cutting energy larger than a cutting time on the work to be cut in a specific time from a crossing point of time of a laser beam and the work to be cut. CONSTITUTION:When an emitting light generated at the time of crossing of a laser beam and the work to be cut 2 is detected with a photoelectric sensor 6, the X axial movement is stopped, a working lens 3 is moved to a set cutting position, and then the focus position is changed to the upper side of the work to be cut. After then, a cutting head 5 is moved in the X axis, next a gas supplying path is changed to a supplying path of oxygen 4-1, and the oxygen is made to blow on the cutting part from a nozzle for a set time. Then, the laser beam output is increased, and further the laser beam moving velocity is increased. In such a way, the turbulence of streaks or melting down caused on the cutting surface of the work to be cut can is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser cutting method for moving the incident axis of a laser beam from a state where it does not intersect with a workpiece to a position where it intersects, and starting cutting from the side end surface of the workpiece, and a method thereof. It relates to the device.

[0002]

2. Description of the Related Art Conventionally, in laser cutting in which a workpiece is cut with the energy of a laser beam, first, a prepared hole is formed in a workpiece (piercing), and the prepared hole is used as a starting point to cut into a desired shape. It is common to do so. When the cutting is started from the prepared hole, in order to prevent the cut surface from being disturbed or melted at the start of the cutting, for example, Japanese Patent Laid-Open No. 2-3
In Japanese Patent No. 0388 and Japanese Patent Laid-Open No. 3-57579, the cutting speed is increased stepwise at the start of cutting. However, when cutting is performed starting from the prepared hole, a workpiece having a desired shape is cut out from the workpiece, and when a large number of workpieces are obtained from one workpiece, the remaining material increases, There was a problem that it was uneconomical. Therefore, in order to solve such a problem, as shown in FIG.
A laser cutting method is performed in which the incident axis of the laser beam 1 is moved from a state where it does not intersect with the workpiece 2 to a position where it intersects, and cutting is started from the side end surface of the workpiece 2. Note that reference numeral 7 indicates the cutting proceeding direction.

[0003]

Since the conventional laser cutting method and its apparatus are configured as described above, when the incident axis of the laser beam 1 is moved to the intersection position with the work piece, the work piece is processed. The laser beam 1 is emitted from the lower part of the object. Therefore, the temperature of the work piece rises from the lower part, and the temperature rising region expands toward the upper part of the work piece 2 in a shape corresponding to the divergent shape of the laser beam 1 and the temperature rises, and the temperature rises to the melting temperature. If it becomes above, a melt will flow down. At this time, since the lower part of the work piece 2 is in a sufficiently preheated state, it is further chain-melted by the retained heat of the flowed melt. Further, since the cutting groove is not yet formed in the lower part of the work piece 2 at the start of cutting, there is no wall for restricting the melt flow, so the melt spreads on both sides of the cutting groove in the lower part of the work piece 2. I will end up. For these two reasons, there is a problem in that, at the start of cutting, the cut surface is disturbed and burned down at the lower part of the work piece 2, and the quality of the work piece is significantly deteriorated.

The inventions set forth in claims 1 to 6 are made in order to solve the above-mentioned problems, and prevent disturbances and burn-through in the scratches generated in the cut surface of the workpiece, and It is an object of the present invention to obtain a laser cutting method for improving the quality of laser.

It is an object of the present invention to provide a laser cutting device capable of processing a high quality cutting start portion by a simple operation.

[0006]

According to a first aspect of the present invention, there is provided a laser cutting method for applying a cutting energy, which is larger than that during cutting, for a predetermined time from a time point of intersection between a laser beam and a workpiece. Is.

In the laser cutting method according to the second aspect of the present invention, a large cutting energy is obtained by increasing the output of the laser beam from the time when the laser beam intersects with the workpiece.

In the laser cutting method according to the third aspect of the present invention, a large cutting energy is obtained by decreasing the relative speed of the laser beam and the workpiece from the time when the laser beam intersects the workpiece. .

According to a fourth aspect of the present invention, there is provided a laser cutting method for detecting light emission generated when a laser beam is applied to a workpiece to detect a crossing region of the laser beam axis and the workpiece. .

According to a fifth aspect of the present invention, there is provided a laser cutting method, which comprises a first step of moving a laser beam to a position intersecting a side end surface of a workpiece, and a laser beam output at the time of cutting at a crossing position. The second step of increasing the output and the third step of increasing the moving speed of the laser beam to the cutting speed are sequentially executed.

According to a sixth aspect of the laser cutting method of the present invention, the distance between the incident axis of the laser beam and the end of the workpiece, the execution times of the second and third steps, and the execution start time are set as follows. It is set according to the material, plate thickness, and processing shape.

According to a seventh aspect of the present invention, there is provided a laser cutting device, which has a memory means for storing a machining program for giving a predetermined cutting energy to the workpiece at the time of intersection between the laser beam and the workpiece. According to the processing program retrieved from the memory means according to the material and plate thickness of the workpiece, the cutting control means is provided for controlling the cutting process.

[0013]

In the laser cutting method according to the present invention, the cutting groove is swiftly cut by applying a cutting energy larger than that at the time of cutting for a predetermined time from the time when the laser beam intersects the work. It can be formed down to the bottom of the work piece. As a result, since the melt flow is regulated, the disorder and the burn-through of the scratches generated on the cut surface of the workpiece are prevented, and the quality of the workpiece is improved.

In the laser cutting method according to the second aspect of the present invention, the change processing of the cutting energy is easy by increasing the laser beam output to obtain a large cutting energy.

In the laser cutting method according to the third aspect of the present invention, the laser oscillator for generating the laser beam has a small capacity by reducing the relative speed of the laser beam and the workpiece to obtain a large cutting energy. it can.

According to a fourth aspect of the present invention, there is provided a laser cutting method, wherein light emission generated when a workpiece is irradiated with a laser beam is detected to detect an intersection region of the laser beam axis and the workpiece. The end position of the workpiece can be detected easily and accurately without adding a complicated mechanism, and cutting can be stopped immediately before the end of cutting based on the detected intersection area, and a stable micro joint can be obtained. Can be formed.

In the laser cutting method according to the fifth aspect of the present invention, the laser beam and the workpiece are relatively moved to the intersecting position in the first step, and the laser beam output is increased in the second step. By increasing the relative speed of the laser beam and the work piece in the step of, the output of the laser beam is made lower than that at the time of cutting up to the intersecting position, so there is less preheating of the lower part of the work piece and Due to the increased laser beam output, the cutting groove is formed down to the lower part of the workpiece, and the same effect as that of the invention of claim 1 is obtained.

According to a sixth aspect of the present invention, there is provided a laser cutting method, wherein a distance between an incident axis of a laser beam and an end of a workpiece is
By setting according to the material, plate thickness, and processing shape of the work piece, it is possible to perform cutting work quickly under optimum conditions.

In the laser cutting device according to the present invention, the cutting energy is applied to the work piece in accordance with the processing program retrieved from the memory means according to the material and plate thickness of the work piece. A high-quality cutting start part can be processed.

[0020]

【Example】

Example 1. FIG. 1 is a schematic view showing a laser cutting apparatus according to an embodiment of the invention of claim 7 for executing the laser cutting method of the inventions of claims 1 to 6, and the same parts as those of the conventional example shown in FIG. The same reference numerals are given and duplicate description is omitted.
In FIG. 1, 3 is a processing lens for condensing the laser beam 1, 4 is a switching portion between the gas supply paths 4-1 and 4-2, and 5 is a nozzle for blowing a melt removal gas to a cut portion of the workpiece 2. 5a is a machining head having a tip portion, and 6 is a photoelectric sensor for detecting the light emission of the irradiation portion generated when the laser beam 1 is irradiated on the workpiece 2, and this photoelectric sensor 6 is the tip portion of the machining head 5. It is provided in the nozzle 5a. 9
Is a folding mirror that reflects the laser beam 1, 11 is a processing lens moving mechanism that moves the processing lens 3 far and far with respect to the workpiece 2, 12 is a laser oscillator that generates the laser beam 1, 13 is an NC device, and 14 is photoelectric A signal processing circuit that processes signals from the sensor 6 and the NC device 13 and supplies the signals to the NC device, and 15 is a servo control circuit that drives and controls the processing lens moving mechanism 11 and the processing table 16 on which the workpiece 2 is mounted. Is.

FIG. 2 is a block diagram showing in detail each part of FIG. 1, in which the NC unit 13 stores a machining program for executing a series of operations in advance, and a memory means 13a for decoding the machining program from the memory means 13a. C as a processing control means for supplying a control signal to the excitation power supply 12a of the laser oscillator 12, the servo control circuit 15, and the switching unit 4.
It has PU13b. The servo control circuit 15 has a linear (circular) interpolation control unit 15a and a speed control unit 15b, and controls the servo motor 16a for driving the machining table 16. The switching unit 4 has a gas selection unit 4a for selecting the type of gas and a gas ejection pressure control unit 4b, and has a supply passage 4-1 for oxygen as an assist gas and a supply passage 4 for argon gas that promotes light emission. -2 and switch.

Next, the operation will be described with reference to the flow chart of FIG. 3 and the schematic showing the cutting order of FIG. In FIG. 4A, in the present embodiment 1, the workpiece 2 has a thickness of 9 mm.
ZnSe processing lens 3 having a focal length of 190.5 mm is moved to a set position so as to focus on the surface of the workpiece and is stopped (steps ST3-1 to ST3-1 to ST3-3).
-3). Then, the type of gas to be ejected from the tip nozzle 5a of the machining head 5 having a hole diameter of 2 mm coaxial with the laser beam 1, for example, the supply path 4-2 of argon gas is selected, and the gas ejection pressure is ejected as a set value ( Step ST3-4
~ 3-6). Then, the beam output condition is set to a set value of 200 W and laser beam irradiation is performed (step ST3
-7 to 3-9), the X-axis moving speed of the processing head 5 is set to a set value, for example, a beam moving speed of 0.5 m / min, and the processing head is moved in the X-axis (step ST3).
-10 to 3-12).

In FIG. 4 (2), when the photoelectric sensor 6 detects light emitted when the laser beam 1 and the workpiece 2 intersect due to the movement of the machining head 5 along the X axis (step ST3-13). The movement is stopped, the processing lens 3 is moved to the set cutting position, and the focus position is changed to 1.0 mm above the surface of the workpiece (step ST3-
14-3-17). Then, the machining head 5 is moved along the X-axis, and the laser beam axis is moved from the set end of the workpiece to the cutting start position inside the workpiece, for example, about 0.5 mm, which corresponds to the width of the cutting groove. Then, it is stopped (steps ST3-18 to 3-20). However, the operation of these steps ST3-18 to 3-20 is performed by the material of the workpiece 2,
It is not absolutely necessary to do it depending on the plate thickness.
Next, the gas supply passage is switched to the oxygen supply passage 4-1 so that the nozzle original pressure is 0.6 kgf / cm ² from the nozzle 5a.
As a result, oxygen is blown to the cutting portion 2a for a set time (steps ST3-21 to 3-24).

In FIG. 4C, thereafter, the beam output is increased from 200 W at a rising time constant of 200 ms to, for example, a set value of 1.2 kW (step ST3-2).
5-3-27). Furthermore, the laser beam moving speed is set to 0 m 300 ms after the laser beam output starts increasing.
/ Min to 1 m / min with a rising time constant of 50 ms (steps ST3-28 to 3-30).

In FIG. 4 (4), by the above operation, the cutting groove 8 is formed as shown in FIG. 4 (3) immediately before the start of laser beam movement, and in the subsequent cutting by the X-axis movement,
As shown in FIG. 4 (4), when the melt flows through the cutting groove 8 (step ST3-31) and the cut surface after processing is observed,
Distortion and burn-through of streak generated on the cut surface of the workpiece 2 are prevented, and the quality of the workpiece is improved.

Now, the rising time constant will be described. In the first embodiment, the changes in the values of parameters such as the laser beam output and the laser beam moving speed are made to follow the following formula (1). K = K1 + (K2-K1) * (1-exp (-t / λ)) (1) Here, the target value of the parameter is K2, the initial value of the parameter is K1, where K2> K1, and the rising time constant is λ. ,
The time from the start of the parameter change is t, and the value of the parameter at time t is K.

In the first embodiment, the time for forming the cutting groove 8, that is, the time from the start of the laser beam output increase to the start of the laser beam movement is set to 300 ms. It depends on the plate thickness. Generally, the thicker the plate, the lower the absorptance of the laser, and the higher the melting point, the longer the time from the start of the laser beam output increase to the start of the laser beam movement. At this time, both the rising speed of the laser beam output as shown in FIG. 5A and the rising speed of the laser beam movement as shown in FIG.
If the settings were made so that the time points (hatched areas in FIG. 5) at which the above values were reached were substantially the same, no defects occurred. In the first embodiment, the coincidence point between the laser beam axis and the end surface of the workpiece is detected by detecting the light emission (blue frame) generated at the machining point with the photoelectric sensor 6, but another method, for example, a television You may make it detect by performing image processing by a camera etc.

Example 2. FIG. 6 shows a second embodiment of the present invention. In the second embodiment, the workpiece 2 having a thickness of 12 is used.
A mild steel coated with the paint 21 with a thickness of 100 μm on the surface of mm is used, and the focal length is 190.5 mm as in the first embodiment.
The processing lens 3 made of ZnSe is used as an assist gas, oxygen is supplied from the nozzle 5a at the tip of the processing head 5 having a hole diameter of 2 mm coaxial with the laser beam, and the nozzle original pressure is 0.6 kgf /
It was sprayed onto the cut portion 2a as cm ² . In the second embodiment, the laser output is 200 W and the laser beam moving speed is 0.8 when the end face is detected by the photodiode, which is the photoelectric sensor 6.
The workpiece 2 was brought closer to the workpiece 2 at m / min, and then the workpiece was scanned as shown in FIG. 6, and the second workpiece end surface on the opposite side was also detected by the change in light emission.

A blue frame is generated at the same time when the laser beam 1 is applied to the end surface of the workpiece, and the light is extinguished at the same time when the laser beam 1 is emitted from the second end surface of the workpiece on the opposite side. 6 is aware of the intersection area, that is, the dimension of the workpiece 2, and after the laser beam 1 is moved by this operation, only the paint 21 on the surface of the workpiece is removed.

Then, the processing lens 3 is raised upward to change the focal point position to 1.5 mm above the surface of the workpiece,
The laser beam 1 is moved from the end of the surface of the work into the work by about 0.6 mm, which corresponds to the width of the cutting groove. After that, the laser beam output is increased from 200 W to 1.75 kW with a rising time constant of 200 ms, and after the laser beam output starts increasing, the laser beam moving speed is increased from 0 m / min to 1 m / min with a rising time constant of 50 ms after 350 ms. Let By this operation, it is possible to prevent the distortion and the burn-through of the scratches generated on the cut surface of the workpiece 2 and to improve the quality of the workpiece.

Further, since the end of the workpiece at the end of cutting is also detected in advance by detecting the intersecting area, the cutting can be reliably stopped 1 mm before the end of the workpiece, and the micro joint can be stably performed. Can also be formed, and there is also an effect that the work piece can be prevented from falling off after the completion of cutting.

Further, since the paint 21 on the surface of the cut portion is removed when the end surface of the workpiece is detected, that is, when the crossing area is detected,
There is also an effect that the deterioration of the purity of oxygen as an assist gas due to the evaporation of the coating material 21 during cutting is reduced, and the cut surface roughness is improved.

Example 3. The third embodiment of the present invention will be described below. Laser beam output for edge detection, scanning speed and laser beam output during cutting, cutting speed, laser beam output rising speed, cutting speed rising speed, laser beam output depending on various conditions such as plate thickness and material of work piece It is necessary to set parameters such as the time from the start of rising to the start of laser beam movement to more suitable values.
In the third embodiment, it is possible to set and store each parameter value according to the conditions such as the plate thickness and material of the workpiece 2.

FIG. 7 shows a part of the parameter diagram showing the processing conditions, which comprises a data number column, an end face detection condition column, a cutting condition column, and a parameter rising speed column. The data number column is a column for numbering data, and the end face detection condition column is input with the average output Sa, frequency Ba, duty Ta, gas pressure Na, focus position Za, and laser beam moving speed Fa at end face detection. In the cutting condition column, the average output Sb during cutting, frequency Bb, duty Tb, gas pressure Nb, focus position Zb, and laser beam moving speed Fb are input, and the parameter rising speed column shows the rising speed Sc of laser beam output, laser The beam movement speed rise Fc and the delay time Dc from the start of increasing the laser beam output to the start of moving the laser beam are input.

This data can be input by the code shown in FIG. Here, G88 is a code for inputting data, L is a code for designating a data number, an end face detection condition column, a cutting condition column, and a parameter rising speed column.
1.1 is the end face detection condition column of data number 1, L1.2 is the cutting condition column of data number 1, and L1.3 is the data number 1
It is a code to input data in the parameter rising speed column of. Symbols such as S indicate the above parameters.

As described above, if the table shown in FIG. 7 is prepared from the combination of proper processing conditions before the cutting processing is performed, good cutting processing of the end face can be performed by the code.
The command form of the end face cutting method according to the third embodiment is, for example,
It is shown as G33 L1.

Example 4. FIG. 9 is a flowchart showing the function of the control device or the automatic programming device that automatically determines the end face detection condition, the cutting condition, and the parameter rising speed condition so that the processing failure does not occur at the cutting portion from the end face of the workpiece. is there. First, after a shape program is created (step ST9-1), a portion to start cutting from the outside of the end surface of the work piece is recognized (step ST9-2), and end surface cutting conditions are set corresponding to the material and plate thickness of the work piece (step). S
T9-3), end face cutting start code input (step ST7
-4), by assigning cutting conditions (step ST7-5), it is possible to create a processing program capable of excellently cutting the end surface of the workpiece (step ST7-).
6). In each of the above-described embodiments, the case where the machining head 5 is moved along the X axis has been described. However, even if the machining table 16 is moved along the X axis, or the machining head 5 and the machining table 16 are relatively moved along the X axis. Good.

[0038]

As described above, according to the first aspect of the invention, the coincidence between the laser beam and the end of the workpiece is detected,
Since the cutting energy is applied to the work piece for a predetermined time from the time of this detection as compared with the cutting work, the cutting groove can be quickly formed even under the work piece. As a result, since the melt flow is regulated, it is possible to prevent the distortion and burn-through of the scratches generated on the cut surface of the workpiece,
The quality of the processed product is improved.

According to the second aspect of the present invention, since the laser beam output is increased to obtain a large cutting energy, the cutting energy change process is easy.

According to the third aspect of the present invention, since the relative speed of the laser beam and the workpiece is reduced to obtain a large cutting energy, the laser oscillator for generating the laser beam should have a small capacity. Can be used.

According to the fourth aspect of the invention, the light emission generated when the laser beam is applied to the workpiece is detected to detect the intersection region of the laser beam axis and the workpiece. , The edge of the work piece can be detected easily and accurately without adding a new complicated mechanism, and the cutting can be stopped immediately before the end of cutting based on the detected intersecting area, and a stable micro Can form joints.

According to the fifth aspect of the invention, the output of the laser beam is lower than that during the cutting process until the laser beam axis coincides with the end of the work, so the preheating of the lower part of the work is performed. And the cutting groove is formed to the lower part of the work piece by the increased laser beam power after the coincidence point. As a result, since the melt flow is regulated, it is possible to prevent the distortion and burn-through of the scratches generated on the cut surface of the workpiece,
The quality of the processed product is improved.

According to the sixth aspect of the present invention, the distance between the incident axis of the laser beam and the end of the workpiece is determined by the material of the workpiece,
Since it is configured to set according to the plate thickness and processing shape,
You can quickly perform cutting under optimal conditions.

According to the seventh aspect of the present invention, the cutting energy is applied to the workpiece according to the machining program retrieved from the memory means according to the material and plate thickness of the workpiece, so that a simple operation is possible. With this, high-quality cutting start part processing can be performed.

[Brief description of drawings]

FIG. 1 is a schematic view showing a laser cutting apparatus according to an embodiment of the invention of claim 7 for performing the laser cutting method of the invention of claims 1-6.

FIG. 2 is a block diagram showing each part of FIG. 1 in detail.

FIG. 3 is a flowchart illustrating a laser cutting method according to the first to sixth aspects of the invention.

FIG. 4 is a schematic diagram illustrating a laser cutting method according to the first to sixth aspects of the invention.

FIG. 5 is a characteristic diagram of laser beam output and laser beam moving speed with respect to time.

FIG. 6 is a schematic view for explaining a laser cutting method according to another embodiment of the invention described in claims 1 to 6.

FIG. 7 is a parameter diagram showing processing conditions.

FIG. 8 is a code diagram for inputting processing conditions.

FIG. 9 is a flowchart for creating a machining program.

FIG. 10 is a schematic diagram illustrating a conventional laser cutting method.

[Explanation of symbols]

 1 Laser Beam 2 Workpiece 13a Memory Means 13b CPU (Processing Control Means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisao Isaka 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Production Technology Research Institute (72) Inventor Yu Kanaoka 5-1-1 Yada Minami, Higashi-ku, Nagoya Mitsubishi Electric Corporation Nagoya Works

Claims (7)

[Claims] 1. A laser cutting method in which an incident axis of a laser beam is moved from a state where the laser beam does not intersect with a workpiece to a position where the laser beam intersects, and cutting is started from a side end surface of the workpiece. A laser cutting method, characterized in that an intersection with an end of a workpiece is detected, and a cutting energy larger than that at the time of cutting is applied to the workpiece for a predetermined time from the detection time. 2. The laser cutting method according to claim 1, wherein the output of the laser beam is increased to obtain a large cutting energy. 3. The laser cutting method according to claim 1, wherein a relative cutting speed of the laser beam and the workpiece is reduced to obtain a large cutting energy. 4. The laser according to claim 1, wherein an intersection region of the laser beam axis and the workpiece is detected by detecting light emission generated when the workpiece is irradiated with the laser beam. Cutting method. 5. A laser cutting method, wherein an incident axis of a laser beam is moved from a state where the laser beam does not intersect with a workpiece to a position where the laser beam intersects with the workpiece so as to start cutting from a side end surface of the workpiece. A first step of moving to a position intersecting the side end surface of the workpiece, a second step of increasing the output of the laser beam to the output at the time of cutting at the intersecting position, and a moving speed of the laser beam up to the cutting speed. A laser cutting method comprising performing a series of operations of a third step of raising. 6. The material of the work piece, the distance between the incident axis of the laser beam and the end of the work piece in the first step, the execution time of the second and third steps, and the execution start time point. ,
The laser cutting method according to claim 5, wherein the thickness is set according to a plate thickness and a cutting shape. 7. A laser cutting device for moving a laser beam incident axis from a state where the laser beam does not intersect the workpiece to a position where the laser beam intersects the workpiece so as to start cutting from a side end surface of the workpiece. A first step of moving to a position intersecting the side end surface of the workpiece, a second step of increasing the output of the laser beam to the output at the time of cutting at the intersecting position, and a moving speed of the laser beam up to the cutting speed. A third step of raising, a memory means for storing a machining program for executing a series of operations in advance, and a cutting process according to the machining program retrieved from the memory means according to the material and plate thickness of the workpiece. A laser cutting device comprising processing control means for controlling