JPH09277071A - Method and device for laser beam machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a piercing time in a laser beam machining method. SOLUTION: In the piercing in which holes 14a are drilled on a work 14 by a laser beam 13, an assist gas is blown against a piercing part, as is a blow gas from a blow nozzle 19, thereby blowing off molten metal and preventing formation of a bulge.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to laser processing, and more particularly to improvement of piercing (prepared hole processing) in laser processing.

[0002]

2. Description of the Related Art A laser processing apparatus is an apparatus for cutting a plate-like work with a laser beam to form products of various shapes. In this cutting process, first, the laser beam is pierced at a position on the work that has nothing to do with the product, and the laser beam is moved along the cutting line such as the shape of the product starting from the through hole formed by the piercing. Then, the work is cut to form a product.

In order to perform the above-mentioned processing, the laser processing apparatus has a lens for converging a laser beam, a nozzle for irradiating the converged laser beam, a work position controller for moving the work in the XY directions, It has a nozzle position control unit that moves the nozzle forward and backward in the Z-axis direction, and a control device that controls the entire device.

Further, while the work surface of the work is not always flat, the distance from the lens to the work is kept constant during cutting and the intensity of the laser beam applied to the work is kept constant. There is a need. Also, the above lens can be replaced with one having various focal lengths, a lens having an appropriate focal length is selected from the material and thickness of the work, and the tip position of the nozzle is the focal length of the lens and the material of the work. The thickness is set so that the lens comes to a predetermined position with respect to the focal position of the lens.

Therefore, if the distance from the tip of the nozzle to the work is kept constant, the distance from the lens to the work will also be constant, so that the work can be irradiated with a laser beam of uniform intensity, and the cutting surface with high accuracy can be obtained. Can be obtained.

Therefore, the laser processing apparatus is provided with a contact type or non-contact type copy sensor, and copy control is performed so as to keep the distance between the tip of the nozzle and the work surface constant. However, the distance between the tip of the nozzle that can be controlled for copying and the processing surface is limited to a certain range (this is referred to as a “copyable range”).

On the other hand, the above piercing is started when the distance between the tip of the nozzle and the work surface is larger than that at the time of cutting. Then, the distance at which the piercing is started is out of the above-mentioned copying possible range.

In order to adjust the distance between the nozzle and the work, the conventional laser processing apparatus has a servo motor and an encoder so that the control device can move the nozzle in the Z-axis direction by a predetermined distance. It has become. But,
The exact distance between the nozzle tip and the work surface cannot be measured. Further, the scanning sensor can accurately measure the distance between the nozzle tip and the workpiece processing surface, but its measuring range is limited to the copying possible range as described above, and compared to the entire movable range of the nozzle, only a part Nothing more.

Conventionally, in such a laser processing apparatus, when the piercing is to be started outside the range in which copying is possible, the following has been done. First, the nozzle is lowered in the Z-axis direction to the copying possible range, the distance between the nozzle and the work surface is measured by the scanning sensor, and the amount of rise of the nozzle from the measured value to the piercing start position is calculated.
The nozzle was raised and piercing was started.

During the piercing, assist gas is blown from the nozzle to cause an oxidation reaction between the assist gas and the molten metal of the workpiece, and the heat of the oxidation reaction is also used to shorten the time required for the piercing. It was done.

Thus, as the piercing is started and progresses, the depth of the hole gradually becomes deeper, the nozzle gradually comes closer to the work, and eventually enters the range where copying is possible, and the hole penetrates the work. Is controlled so that the distance at the time of cutting is maintained. However, there is also a method of keeping the nozzle at a constant height during the piercing and lowering the nozzle to the scanning range after the piercing.

FIG. 7 is a diagram showing a state of piercing by the above-mentioned conventional technique. In the figure, reference numeral 1 denotes a nozzle, from which laser beam irradiation and assist gas spraying are performed, and a hole 2 a is formed in the work 2.

[0013]

However, in the above method, since the nozzle is once moved into the scannable range and then raised again, the operation of the nozzle is complicated, the operation time becomes long, and the piercing takes a long time. There was a problem of hanging.

With the formation of the hole 2a, the molten metal rises around the hole, and the raised portion 3 is formed after processing. In such a portion where the raised portion 3 is formed, the plate thickness of the work 2 becomes thicker, which may result in defective cutting, or the nozzle 1 and the raised portion 3 may interfere during cutting.

Further, when the raised portion 3 is formed, the scanning sensor outputs an incorrect interval, or the contact of the sensor has a raised portion 3.
In some cases, the distance between the nozzle and the work changed, which caused defective cutting.

Therefore, when cutting the raised portion 3 after piercing, it is necessary to change cutting conditions such as the height of the nozzle and the output of the laser beam only here, and the piercing work is complicated and time-consuming.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a laser processing method and apparatus capable of shortening the piercing time in laser processing.

[0018]

In order to achieve the above object, the present invention sets a nozzle at a predetermined position with respect to a focal position of a lens that converges a laser beam, and the nozzle can be copied from a work or more within a range. In the laser processing method of separating and starting piercing, the calculated position of the nozzle for starting piercing is obtained from the Z-axis position of the nozzle tip and the thickness of the work, and the piercing is performed by moving the nozzle to the position. It is characterized in that the nozzle position is corrected by bringing the nozzle close to the work, measuring the distance between the nozzle and the work by the scan sensor after the nozzle has entered the range where copying is possible.

At this time, the correction amount is stored to correct the nozzle position for starting piercing from the next time onward,
When bringing the nozzle closer to the work, it is desirable that the movement limit of the nozzle be set to the lowest end where the nozzle can move.

A laser processing apparatus of the present invention for carrying out the above method is provided with a nozzle for irradiating a laser beam, and a Z
In a laser processing apparatus having a Z-axis management unit that moves in the axial direction and a scanning sensor that measures a distance between a nozzle and a work, the Z-axis management unit is based on a plate thickness of the work input in advance. To move the nozzle to the calculated piercing start position to start piercing, then move the nozzle toward the work, measure the distance between the nozzle and the work by the scanning sensor, and use the measured value to measure the nozzle The feature is that the position in the Z-axis direction is corrected.

Another method of the present invention is a laser processing method in which piercing of a work is performed by a laser beam and an assist gas is blown to a processing portion during piercing, wherein blow gas is blown to the processing portion.

The blow gas may be blown from a direction intersecting with the laser beam, or the blow gas may be blown after a predetermined time has elapsed after the start of piercing, and the laser processing method follows the distance between the nozzle and the work. In the case of the laser processing method capable of performing the scanning control for sensing the position of the nozzle with respect to the work by sensing by the sensor, the scanning control is performed during the piercing.
It is desirable to set it to F.

A laser processing apparatus for carrying out the above method is characterized in that a blow nozzle for blowing blow gas to the work is provided in the laser processing apparatus for performing piercing by a laser beam while blowing assist gas from the nozzle onto the work.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram of an embodiment of the present invention. In the figure, 10 is a torch, and a nozzle 11 is attached to the tip. A lens 12 is provided inside the torch 10, and a laser beam 13 emitted from a laser oscillator is converged by the lens 12 inside the torch 10 by a reflecting mirror (not shown), and the nozzle 1 is provided coaxially with the laser beam 13.
1 to the work 14 are irradiated. Nozzle 11 is torch 1
0, for example, screwed onto lens 1
It can be set to a predetermined position with respect to the distance from 2, that is, the focal position of the lens.

The work 14 is fixed on an XY table (not shown) of the laser processing apparatus and is movable in the X and Y planes. Further, the torch 10 can move back and forth in the Z-axis direction. Further, at the lower end of the torch 10, for example, a capacitance type non-contact type copying sensor 15 is provided, and the distance between the tip of the nozzle 11 and the work 14 can be measured within the range in which copying is possible, and copying control is performed. This makes it possible to keep this distance constant.

An assist gas inflow port 16 is provided below the lens 12 of the torch 10, and one of oxygen, nitrogen and air is supplied from a gas supply source (not shown). The assist gas is blown out from the hole 11 a at the tip of the nozzle 11 almost in parallel with the laser beam 13, and the hole 14 of the work 14
It is blown into the inside of a to accelerate the oxidation reaction of the molten metal, and the heat of the oxidation reaction promotes the progress of piercing.

A support 17 is attached to the left side surface of the torch 10, a blow gas inlet 18 is formed therein, and a blow nozzle 19 is attached. A blow gas composed of nitrogen or air is supplied to the blow gas inlet 18 from a gas supply source (not shown). The blow nozzle 19 blows blow gas in a direction intersecting with the laser beam 13.

FIG. 2 is a block diagram of a control system of the laser processing apparatus of the present invention. The main control unit 21 is composed of a computer and controls the entire laser processing apparatus. Although not shown, an input device such as a keyboard for inputting processing conditions such as the work thickness, the piercing start position, the laser output, and the shape of the molded product is provided. Have. This main control unit 21 has
A laser control unit 22, an XY position control unit 23, and a Z axis management unit 24 are connected.

The laser control unit 22 increases / decreases the laser output of the laser oscillator 25, turns it on and off, and controls the assist gas device 26 to open / close the assist gas and adjust the pressure.

The XY position controller 23 includes an X-axis amplifier 2
Servo motors 29 and 30 via the 7 and Y-axis amplifier 28
Are connected, and encoders 31 and 32 are provided on the servo motors 29 and 30, respectively. With such a configuration, the work 14 on the XY table can be moved to any position on the XY plane, and the position information after the movement can be transferred to the main controller via the XY position controller 23. Enter in 21. Therefore, the work can be freely moved according to the shape of the molded product input to the main control unit 21.

The Z-axis management section 24 includes a servo motor 35 and an encoder 3 via a Z-axis amplifier 33 and a Z-position control section 34.
6 is connected, and the nozzle 11 is freely movable in the Z-axis direction,
In addition, the position signal of the nozzle 11 from the encoder 36 is input to the main controller 21. A copying control unit 37 is connected to the Z-axis management unit 24, and the copying control unit 37 is connected to the copying sensor 15
Is connected. The scanning sensor 15 is of a capacitance type and a non-contact type.

Next, the operation of the first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a flowchart showing the operation of the Z-axis management unit 24, and FIG. 4 is a diagram showing the relationship between the Z-axis height of the nozzle 11 and the passage of time in the embodiment of FIG. In starting the piercing, conventionally, the nozzle is moved in the Z-axis direction to once descend to the range in which copying is possible, and then raised again to determine the piercing start position. In this embodiment, a simpler operation is performed. It can be done in.

Prior to the start of the flow chart, necessary data such as the plate thickness of the work, the piercing start height, the shape of the molded product, etc. are input to the main control section 21 in advance. When an instruction to start piercing is issued from the main control unit 21 to the Z-axis management unit 24, the Z-axis management unit 24 issues an instruction to drive the servo motor 35 to the Z-axis amplifier 33 (101). When the servo motor 35 rotates, the nozzle 11 starts descending, but the amount of descending is determined by the encoder 36 in each Z position control unit 3.
4 is input. The Z-axis management unit 24 monitors the signal from the Z-position control unit 34 and waits for the nozzle 11 to reach the calculated piercing start position (103).

When the nozzle reaches the calculated piercing start position, piercing is started in the same manner as in the above-mentioned embodiment. Then, as the piercing progresses, the nozzle 11 is gradually lowered downward. This lowering is limited to the lower end of the drivable range of the nozzle 11 (105).

As the piercing progresses, the nozzle 11 continues to descend, and eventually the distance between the tip of the nozzle and the workpiece machining surface reaches the scanning range of the scanning sensor 15 (10
7). Therefore, the distance from the tip of the nozzle to the work surface is accurately measured by the scanning sensor 15. Then, calculate the difference from the calculated nozzle position used up to that time,
The Z-axis position of the nozzle 11 is corrected (109).

Since the distance from the nozzle tip to the work surface is transmitted to the Z-axis management unit 24 and the main control unit 21 as described above, the main control unit 21 determines the target position for cutting and Z
An instruction is given to the axis management unit 24 (111), and the Z-axis amplifier 3
3, the servo motor 35, the encoder 36, and the Z position controller 34 move the nozzle 11 to the cutting position (11
3). At this time, piercing is also completed.

When the nozzle 11 is moved to the cutting position, the copying control section 37 is instructed to switch to the copying control (11
5). As a result, the nozzle is kept at a constant distance from the work surface, and the work is cut and processed according to the shape of the molded product that has been input in advance.

As described above, according to this embodiment, piercing is started at the calculated piercing start position, and then the nozzle position is corrected by lowering the nozzle 11 and entering the scan controllable range. There is. Therefore,
It is not necessary to temporarily move the nozzle down to the copy controllable range and then move it up to the piercing start position, and the piercing time can be shortened.

Further, since the lower limit position when lowering the nozzle is set to the lowermost end, that is, the lower limit position of the nozzle in the laser processing apparatus, the nozzle can trace when the work surface is lower than the calculated position. It is possible to avoid a situation in which correction cannot be made due to the inability to enter the range. If the work surface is higher than the calculated position,
You will be able to enter the copyable range earlier than planned.

Further, by storing the above correction amount, the position of the nozzle 11 in the second piercing can be corrected, and the accuracy of the height control after the second time can be improved.

In the above embodiment, the previous correction amount is stored and reflected in the next correction. However, the correction amounts are stored a plurality of times and the average value of them is calculated after that. It may be a correction amount.

Next, a second embodiment of the present invention will be described with reference to FIGS. First, as described in the above-described embodiment, the work is irradiated with the laser beam 13 at a position where the distance H (FIG. 5A) between the tip of the nozzle 11 and the work 14 is set wider than the possible range h. Start piercing. At the same time, the assist gas is sprayed from the nozzle 11. The processed portion of the work 14 irradiated with the laser beam is melted and molten metal 14b starts to be formed. The assist gas is blown into the molten metal 14b to promote the oxidation reaction, and the holes 1
4a is formed and piercing is started. Next, blow gas 19a is blown from blow nozzle 19 into hole 14a.
Is blown towards.

Since the blow gas is blown in the direction intersecting with the laser beam, it is possible to prevent the molten metal around the hole 14a from being blown off and the rising portion 3 shown in the conventional example from being formed. Further, it is desirable to delay the start of blowing the blow gas by an arbitrary time from the start of blowing the assist gas so that the blow gas does not block the assist gas.

Irradiation of the laser beam is continued, and the hole 14a
Becomes gradually deeper as shown in FIG. 5 (b), and eventually penetrates the work as shown in FIG. 5 (c), and blow gas 1
9a is stopped.

After this, the nozzle 11 is controlled by the main controller 21 and the work is cut while keeping the distance h to the work 14 constant within the range in which copying is possible. As described above, according to the present invention, since the raised portion 3 is not formed, it is possible to immediately shift to the cutting distance h and other processing conditions after the piercing is completed.
It is possible to prevent cutting failure at the top of the ridge and reduce the laser processing time.

In the above embodiment, the blow nozzle 19
However, a plurality may be provided. Further, the height H of the nozzle 11 gradually decreases during the piercing so that it finally reaches h.
It may be kept constant as it is and lowered to h after piercing.

FIG. 6 is a diagram showing a third embodiment of the present invention. When the copying control is turned on during the piercing as in the above embodiment, when the copying sensor 15 is a capacitance type non-contact sensor, it is erroneous by detecting the molten metal scattered from the hole 14a. Prints the interval and, as a result,
There was a case where the distance between the nozzle and the work changed and the piercing became defective.

Therefore, in this embodiment, the following control is performed according to the flow chart shown in FIG. When the nozzle 11 descends (201) and the interval (piercing height) between the nozzle 11 and the work 14 reaches a predetermined height, the copying control is turned off (203).

A laser beam is output and the assist gas is opened at the same time (205). Then, wait a specified time until the surface of the work begins to melt (20
7) The blow gas is opened (209).

The blow gas may be blown until the piercing is completed, and the time required for the piercing can be known in advance. Therefore, the control device measures the time from the start of blowing the blow gas, and when the predetermined blow time has elapsed (211), the blow gas is closed (21).
3).

Thus, the piercing is completed. Therefore,
The copying control is turned on (215), the height of the nozzle 11 is maintained at the height for cutting (217), and the cutting is started (219).

In this way, the copying control is turned on during the piercing.
By using FF, it is possible to prevent erroneous measurement of the distance between the nozzle and the workpiece processing surface, and it is possible to prevent piercing failure.

[0053]

As described above, according to the present invention, in the laser processing method of starting piercing from outside the range in which copying is possible, the nozzle of piercing starting from the Z-axis position of the nozzle tip and the thickness of the workpiece Obtain the calculated position, move the nozzle to that position and perform piercing, bring the nozzle closer to the work, and after the nozzle enters the range that can be copied, measure the distance between the nozzle and the work with the copy sensor Since the correction is performed, piercing can be performed in a short time.

If the above-mentioned correction amount is stored and the nozzle position for starting piercing from the next time is corrected,
Further, the time can be shortened. If the movement limit of the nozzle is set to the lowest end where the nozzle can move, even if the work surface is below the calculation, it is possible to smoothly shift to the copying control. Further, when blow gas is blown together with the assist gas to the processing portion during piercing, the raised portion is not formed after the piercing processing, the piercing processing is easy and the processing time can be shortened.

If the blow gas is blown from the direction intersecting with the laser beam, the formation of the raised portion can be effectively prevented. In addition, if the blow gas is blown after a predetermined time has passed after the start of piercing, the blow gas does not blow the assist gas.

Further, when the laser processing method is capable of controlling the copying, the copying control is turned off during the piercing.
If set to F, it is possible to prevent erroneous piercing due to a wrong nozzle position during piercing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part showing a main part configuration of a laser processing apparatus of the present invention.

FIG. 2 is a block diagram showing a configuration of a control system of the laser processing apparatus of the present invention.

FIG. 3 is a flowchart showing a first embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the nozzle position and the passage of time in the embodiment of FIG.

FIG. 5 is a diagram showing a piercing state according to the present invention,
(A) shows a state just after starting, (b) shows piercing, and (c) shows a piercing completed state.

FIG. 6 is a flowchart showing a third embodiment of the present invention.

FIG. 7 is a sectional view of an essential part for explaining a conventional laser processing method.

[Explanation of symbols]

 11 Nozzle 12 Lens 13 Laser Beam 14 Workpiece 14a Hole 15 Copy Sensor 19 Blow Nozzle 19a Blow Gas

Claims (9)

[Claims] 1. A laser processing method in which a nozzle is set at a predetermined position with respect to a focal position of a lens for converging a laser beam, and the piercing is started by separating the nozzle from a work by a distance more than a traceable range. Calculating the position of the nozzle for starting piercing from the Z-axis position and the thickness of the work, moving the nozzle to that position for piercing, bringing the nozzle closer to the work, and moving the nozzle into the range where copying is possible. A laser processing method characterized in that the position of a nozzle is corrected by measuring a distance between a rear nozzle and a work by a scanning sensor. 2. The laser processing method according to claim 1, wherein the correction amount is stored and the nozzle position at which piercing is started from the next time onward is corrected. 3. The laser processing method according to claim 1, wherein when the nozzle is brought close to the work, the movement limit of the nozzle is set to the lowest end at which the nozzle can move. 4. A laser processing apparatus comprising: a nozzle for irradiating a laser beam; a Z-axis management unit for moving the nozzle in the Z-axis direction; and a scanning sensor for measuring a distance between the nozzle and a work. The Z-axis management unit moves the nozzle to a calculated piercing start position based on the plate thickness of the workpiece input in advance to start piercing, and then moves the nozzle toward the workpiece to cause the scanning sensor to nozzle the nozzle. A laser processing apparatus, which measures a distance between a workpiece and a work, and corrects the position of the nozzle in the Z-axis direction based on the measured value. 5. A laser processing method in which piercing of a work is performed by a laser beam and an assist gas is blown to a processed portion during piercing, wherein a blow gas is blown to the processed portion. 6. The laser processing method according to claim 5, wherein the blow gas is blown from a direction intersecting the laser beam. 7. The laser processing method according to claim 5, wherein the blow gas is blown after a lapse of a predetermined time after the start of piercing. 8. The laser processing method is a laser processing method capable of performing scanning control for sensing a distance between a nozzle and a work by a scanning sensor to keep the position of the nozzle relative to the work constant, and during the piercing. 8. The laser processing method according to claim 5, wherein the copying control is turned off. 9. A laser processing apparatus for performing piercing by a laser beam while blowing an assist gas from a nozzle, wherein a blow nozzle for blowing a blow gas to the work is provided.