JPH03165979A - Method and device for laser beam machining - Google Patents

Abstract

PURPOSE:To shorten the piercing time and to improve operability in passing through a piercing hole on a work by a laser beam by detecting the sudden change of frequency of a piercing sound generated on the inside of a laser beam nozzle by a sound sensor. CONSTITUTION:The sudden change of frequency generated at the time of passing through the piercing hole 31 by the laser beam LB on the work W positioned on a work table 11 is detected and a piercing hole passing through completion signal is outputted to an I/O unit 55. Further, the signal is transferred to a detection amplifier 53 and an ON signal is given to a laser beam oscillator 3 from an NC device 57 and in order to cut the work W by the laser beam LB, a microphone 49 for detecting the sound is provided on the inside of the laser beam nozzle 27 provided at the lower part of a machining head assembly body 13. The microphone 49 is connected to the detection amplifier 53 and the detection amplifier 53 and the laser beam oscillator 3 are connected by a signal cable 51 via the NC device 57, by which the change of frequency of the sound in the laser beam nozzle 27 can be detected regardless of material and thickness of the work W.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) This invention provides an acoustic detection sensor that detects whether or not the piercing is completed when a laser beam penetrates a piercing hole in a workpiece. The present invention relates to a laser processing method and an apparatus thereof.

(Prior art) With conventional laser processing means, when drilling a pierced hole by irradiating a laser beam onto a workpiece, it is difficult to determine whether the pierced hole has penetrated or not.
Since there is no detection of whether or not the penetration has been completed, a longer penetration completion time has been set in advance and stored in the NC device, and machining has been performed based on the time specified on the NC machining program.

(Problems to be Solved by the Invention) However, with conventional laser processing means, the time required to complete piercing the piercing hole must be set to a sufficient length, which wastes time and increases the processing time. was there.

In addition, the length of time required to complete piercing the piercing varies depending on the material and plate thickness, so there is a problem that requires knowledge during processing.

The purpose of this invention is to improve the above-mentioned problem by detecting, using an acoustic detection sensor, the rapid frequency change of the drilling sound generated in the laser nozzle when a laser beam passes through the piercing hole in the workpiece, and by detecting the rapid frequency change in the piercing sound that occurs in the laser nozzle. It is an object of the present invention to provide a laser processing method and an apparatus for the same, which aim to shorten the processing time and improve operability for the operator.

[Structure of the invention rIi. ] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a laser processing method in which a laser beam is focused and irradiated onto a workpiece to cut the workpiece. Detects the sudden frequency change of the piercing sound that occurs when the piercing hole is penetrated, and transfers this detection signal to the NC device,
This is a laser processing method in which the workpiece is then cut with a laser beam based on the NC processing program of the NC device.

In addition, the present invention is applicable to processing in which a laser beam oscillated by a laser oscillator is focused and irradiated onto a workpiece positioned on a work table. A laser processing apparatus was constructed by providing an acoustic detection sensor in the laser nozzle, connecting the acoustic detection sensor to a detection amplifier, and communicating the detection amplifier and laser oscillator with a signal cable via an NC device.

(Function) By adopting the laser processing method and device of the present invention, a control unit detects a sudden change in the frequency of the drilling sound that occurs when a laser beam penetrates a piercing hole in a workpiece positioned on a work table. Transfer the signal to the NC device, manually send the skip signal to the N
The C device gives an ON signal to the laser oscillator, and the workpiece is cut by the laser beam.

4 (Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

To facilitate understanding, the overall configuration of a general laser processing apparatus 1 that performs laser processing on a workpiece W will be briefly described.

Referring to FIG. 5, the laser processing device 1 is equipped with a laser oscillator 3, and this laser oscillator 3 is configured to oscillate a laser beam LB toward the laser processing device 1. It is attached to the side.

The laser processing apparatus 1 includes a base 5, a post 7 vertically erected from the base 5, and an overhead beam 9 with the post 7 supported horizontally and cantilevered above the base 5.

A work table 11 is provided on the base 5, and on the upper surface of the work table 11 there are a number of slide balls (not shown) that horizontally support a sheet-like plate material (hereinafter referred to as a work) W to be processed. (not shown) is rotatably mounted.

A processing head assembly 13 is attached to the tip of the overhead beam 9.
A mirror assembly 15 and a condensing lens 17 are housed inside.

The mirror assembly 15 is configured to reflect the laser beam LB emitted from the laser oscillator 3 toward the workpiece W.

The condensing lens 17 is arranged so as to condense the laser beam LB and to apply the laser beam LB to the workpiece W together with an assist gas (inert gas).

Therefore, the laser processing apparatus 1 having the above configuration is configured to receive the laser beam LB from the laser oscillator 3 and to direct the laser beam LB onto the workpiece W via the condensing lens 17 of the processing head assembly 13.

In order to move and position the workpiece W to be processed, the laser processing device 17 is provided with movable first carriages 1 and 9, and a sixth carriage holding a plurality of clamp devices 23 for clamping the workpiece W. Two carriages 21 are provided.

The first carriage 19 is movably supported by a pair of rails 25 attached parallel to each other on both sides of the upper part of the base 5, and can freely approach and move away from the processing area directly under the processing head assembly 13 during driving. It is.

The second carriage 21 holding the clamp device 23 is slidably supported above the first carriage, and is horizontally movable by driving in a direction perpendicular to the rail 25.

Therefore, the workpiece W gripped by the clamping device W23 can be transferred below the processing head assembly 13 on the worktable 11 by the movement of the first and second carriages 19.21.

In the above configuration, the work W is processed by the laser beam LB by positioning the work W on the work table 11 directly below the processing head assembly 13 using the first and second carriages 19.21.

Of course, the laser beam LB emitted by the laser oscillator 3 is applied to the processing head assembly 13 and is directed downward by the mirror assembly 15 as shown by the arrow. After the light is focused by the focusing lens 17,
Can be applied with Work W hair assist gas.

A laser nozzle 27 is provided at the bottom of the processing head assembly 13.

As shown in FIG. 1, the laser nozzle 27 has a tapered conical shape, and the workpiece W located directly below it is set at an appropriate distance by means such as a distance detection sensor (not shown). It is maintained.

The size of the light emitting port 29 of the laser nozzle 27 is made variable depending on the material and plate thickness of the workpiece W to be processed. Therefore, the pierced hole 31 is approximately the same size as the light emitting port 29. It will be the same.

The laser nozzle 27 has an annular double structure formed by an inner wall 33 and an inner chamber 35 and an outer chamber 37. The inner chamber 35 and the outer chamber 37 each have an assist gas (inert gas) supply pipe. The three (hereinafter simply referred to as gas feed pipes) and 41 are directly connected.

Assist gas for cutting the workpiece is supplied from the three gas supply pipes in the inner chamber 35, and assist gas for shielding is supplied from the gas supply pipe 41 in the outer chamber 37, while adjusting the pressure inside the laser nozzle 27. It is inserted, circulates inside the inner chamber 35 and the outer chamber 37, and is ejected from the ejection ports 43 and 45.

The assist gas for cutting the workpiece protects and cools the condenser lens 17, and also serves to blow off the melt (splatter) during cutting the workpiece.
As shown in FIG. 1, it serves to block outside air (air) outside the cutting section.

A bracket 47 is provided at an appropriate position near the gas feed pipe 39 in the inner chamber 35 of the laser nozzle 27, and a sound detection microphone 49 as a sound detection sensor is provided on this bracket 47.

The four acoustic detection microphones (hereinafter simply referred to as acoustic microphones) and their accessories are shielded from the heat of the laser beam LB by the assist gas and placed in a state where they are hardly affected by the laser beam LB. However, in order to avoid the effects of radiant heat, the main body is made of, for example, a highly heat-resistant Teflon resin material.

Next, a method of detecting penetration of the piercing hole 31 due to a change in acoustic quality in this embodiment will be described with reference to the block diagram shown in FIG. 2.

The four acoustic microphones in the laser nozzle 27 are connected to a detection amplifier 53 by a signal cable 51, and further connected to an I/O
It is connected to unit 55.

The detection amplifier 53 is assembled in a strong electric panel (not shown) installed outside the laser processing device 1, and
/O unit 55 and acoustic microphone 49 of laser nozzle 27
It serves as a power source for the four acoustic microphones and controls communications between the two.

Further, the I/O unit 55 is assembled inside the NC console, and performs human output of signals from an automatic control device (hereinafter referred to as the NC device) 57.

The I/O unit 55 is connected to the NC via the signal cable 51.
It is connected to the apparatus and further connected to the operating source of the laser oscillator 3 of the laser processing apparatus 11 0 .

With the above configuration, as shown in FIG. 4, first, in step S1, the workpiece W is placed at a processing position on the worktable 11, and the position of the piercing hole 31 is determined.

The assist gas sent into the inner chamber 35 of the laser nozzle 27 by the ON signal of the four acoustic microphones from the detection amplifier 53 in step S2 becomes a sound source when machining the piercing hole 31 in the workpiece W is started, together with the laser beam. The frequency of the sound is detected and an analog signal is transferred to the detection amplifier 53 in real time.

When the signals from the four acoustic microphones are output from the NC device 57, the detection amplifier 53 turns on the power to the four acoustic microphones through the I/O unit 1-55 and receives the analog signal.

Next, in step S3, the laser oscillator 3 is activated, and the laser beam LB starts machining the piercing hole 31 in the workpiece W.

When the piercing hole 31 penetrates in step S4, A ↑ 1 The pressure of the cyst gas and the height of the nozzle are constant, but only the change in the shape of the work W is affected by the frequency of the sound whose source is the processing start point. receive.

A sudden change in frequency is detected by the detection amplifier 53,
A piercing hole penetration signal is output to the I/O unit 55.

In step S5, the I/O unit 55
The acoustic microphones are turned on by ON signals from the four acoustic microphones, and this signal is transferred to the detection amplifier 53.

Furthermore, the piercing hole 31 penetration completion signal from the detection amplifier 53 is turned on, and the skip signal is manually sent to the NC device.

Next, in step S6, the laser oscillator 3
When an ON signal is received from the laser processing device 1, the laser processing device 1 is activated, moves the workpiece W, and starts cutting the workpiece W into a predetermined shape using the laser beam LB, as shown in FIG.

As described above, in the laser processing method and its apparatus of the present embodiment, the sharp drilling sound generated when the laser beam LB penetrates the via hole 31 into the work W positioned on the work table 11 2 1. detects the change in frequency, outputs a piercing hole completion signal to the I/O unit 55, further transfers the signal to the detection amplifier 53, gives an ON signal to the relay laser oscillator 3 from the NC device 57, and outputs the piercing hole completion signal to the I/O unit 55. In order to cut the workpiece W by the N.
Since the detection amplifier 53 and the laser oscillator 3 are connected by the signal cable 51 via the C device 57, the laser nozzle 27 can be
Changes in the frequency of sound within can be detected. Further, the sound detection microphone 49 can perform stable detection without being affected by spacks and dust.

It should be noted that the present invention is not limited to the embodiments described above, but can be implemented in other embodiments by making appropriate changes.

1 1 [Effects of the Invention] As can be understood from the description of the embodiments above, according to the present invention, the drilling sound generated when a laser beam passes through a piercing hole in a workpiece positioned on a work table can be reduced. Detects a sudden change in frequency, transfers the piercing completion signal to the detection amplifier, manually outputs a skip signal to the NC device, and turns the laser oscillator on from the NC device.
In order to give a signal and cut the workpiece with a laser beam, an acoustic detection sensor is installed in the laser nozzle installed at the bottom of the processing head assembly, and the acoustic detection sensor is connected to a detection amplifier, and the NC device By connecting the detection amplifier and the laser oscillator via a signal cable, changes in the acoustic frequency within the laser nozzle can be detected regardless of the material or thickness of the workpiece, and unnecessary piercing penetration time can be set. The fact that the penetration has been completed can be accurately known in a short period of time without any problems, and the operator's operability can be improved, thereby increasing the productivity of laser processing.

1 4 Furthermore, since the acoustic detection sensor is located above the workpiece, it is possible to achieve the effect that stable detection is possible without being affected by splatter and dust.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view of a laser nozzle embodying the present invention, Fig. 2 is a block diagram illustrating a device for detecting changes in acoustic frequency, and Fig. 3 shows a state in which a workpiece is cut by a laser beam. 4 is a flowchart explaining the process of the laser processing method, and FIG. 5 is a schematic plan view shown in FIG.
FIG. 1 is a plan view of a laser processing device including a laser oscillator. 1... Laser processing device, 3... Laser oscillator 11.
...Work table 27...Laser nozzle 31...
・4 piercing holes...acoustic detection microphone 51...signal cable 53...detection amplifier 55・
...I/O unit LB...Laser beam 57...
・Automatic control device

Claims (2)

[Claims] (1) In a laser processing method in which a laser beam is focused and irradiated onto the workpiece to cut the workpiece, a sudden change in the frequency of the drilling sound that occurs when the laser beam passes through a pierced hole in a positioned workpiece is detected. A laser processing method characterized in that the detection signal is transferred to an NC device, and then a workpiece is cut with a laser beam based on an NC processing program of the NC device. (2) In a laser processing device equipped with a laser nozzle installed at the bottom of a processing head that focuses a laser beam emitted from a laser oscillator and irradiates it onto a workpiece positioned on a worktable, acoustic detection is performed on the laser nozzle. What is claimed is: 1. A laser processing device comprising: a sensor for acoustic detection; the sensor for acoustic detection is connected to a detection amplifier; and the detection amplifier and a laser oscillator are connected by a signal cable via an NC device.