JPH0768394A - Cutting condition monitoring device for heat cutting device - Google Patents

Abstract

PURPOSE:To provide a cutting condition monitoring device which is excellent in the environmental resistance and has no adverse effect of disturbance by ejecting the gas at a work to be cut, and detecting the repulsive pressure of the gas from the work to be cut by a pressure sensor to detect the cutting condition. CONSTITUTION:A pressure sensor 15 is arranged on a nozzle member 7 on the downstream side of the cutting direction 3, and the repulsive pressure of the gas in the vicinity of a cutting groove 6 of a work 1 to be cut is detected. When the cutting groove 6 is not sufficiently formed and the gas from a nozzle 10 is not smoothly released downward from the cutting groove 6 as indicated by the reference symbol 13, the pressure to be detected by the pressure sensor 15 is increased. The output of the pressure sensor 15 is given by a processing circuit 36, and the processing circuit 36 controls a moving means 37 and moves the nozzle member 7 at the constant speed in the preliminarily set cutting direction 3 by keeping the nozzle 10 at the constant distance from the surface of the work 1 to be cut. The processing circuit 36 also actuates a laser beam control means 38 to drive a laser beam source 39 to generate the laser beam 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for monitoring a cutting state in a thermal cutting device for cutting a material to be cut with a thermal cutting beam such as a laser beam.

[0002]

2. Description of the Related Art In a typical prior art, a laser beam is applied to a material to be cut, for example, a steel plate, etc., and a sensor for detecting a sound is used in a state where the laser beam is moving in a predetermined cutting movement direction. An abnormality is detected by identifying a change in sound caused by a change in the disconnection state as compared with the sound when the disconnection is being performed.

In the prior art using such a sound sensor, the adverse effect of noise in the surrounding environment is large, and a large amount of signal processing circuit is required to remove this noise, and therefore the configuration becomes complicated and expensive. There's a problem.

In other prior art, for example, Japanese Patent Laid-Open No. 3-2 is used.
3092. In this prior art, when heat cutting is performed while irradiating the material to be cut with a laser beam, the light reflected by the material to be cut is optically detected by a sensor, and thus the heat cutting portion corresponding to the light reflection state is detected. Detect the cutting quality of.

In the prior art using such an optical sensor, there is a problem that the adverse effect of ambient light of the surrounding environment directly occurs. In order to solve this problem, it is necessary to darken the vicinity of the optical sensor or cover it so that ambient light from the vicinity of the sensor does not enter the sensor. Therefore, the actual thermal cutting work is in progress. As a method for trying to monitor in-process, there is a problem that it becomes an obstacle and lacks reliability.

Further, in this prior art, there is a problem that the light condensing portion such as the lens of the optical sensor is contaminated at the time of thermal cutting by the laser beam, and such an environmental factor cannot be ignored.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cutting condition monitoring device for a thermal cutting device, which is excellent in environmental resistance, has less adverse effects of disturbance, is easy to maintain, and has no malfunction.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a cutting state monitoring device for a thermal cutting device which irradiates a material to be cut with a thermal cutting beam while moving it in the cutting movement direction to provide a thermal cutting device. A nozzle member for injecting gas onto the material to be cut,
A cutting state monitoring device for a thermal cutting device, comprising: a pressure sensor that detects a repulsive pressure of gas from a material to be cut.

Further, the pressure sensor of the present invention is characterized in that it is arranged on the downstream side in the cutting movement direction.

Further, the nozzle member of the present invention is characterized in that it is provided with a follow-up means for holding the pressure sensor and locating the pressure sensor at the downstream side in the cutting movement direction to follow the pressure sensor.

The pressure sensor of the present invention is characterized in that a plurality of pressure sensors are provided at intervals in the circumferential direction, and the output state difference between the pressure sensors is calculated to monitor the disconnection state.

[0012]

In the thermal cutting apparatus of the present invention, not only a laser beam but also a thermal cutting beam such as a flame of a burner burning gas fuel or plasma and the like are used to cut and move a material to be cut, such as a steel plate. If a constant pressure distribution is achieved in the vicinity of the thermal cutting beam on the surface of the cutting portion by the thermal cutting beam, it means that stable cutting is performed, The present invention makes it possible to detect the state of thermal cutting by a simple method of detecting pressure, and the present invention is very effective for in-process monitoring.

According to the present invention, when injecting gas from the nozzle member toward the material to be cut on the outer periphery of the heat cutting beam,
This gas is produced by selecting an inert gas such as argon or nitrogen when the material to be cut is a metal such as stainless steel and titanium and by injecting such an inert gas on the outer circumference of the heat cutting beam. The action of blowing away the metal melted by the thermal cutting beam can be achieved without burning the material to be cut. Further, when oxygen is used as the gas injected at the outer periphery of such a thermal cutting beam, the material to be cut, such as soft iron, burns,
Therefore, the combustion heat is used together with the heat of the heat cutting beam,
A thick material to be cut can be cut, and the cutting speed can be improved.

The pressure sensor is arranged on the downstream side in the cutting movement direction, that is, behind the nozzle member, whereby the cutting groove or the bottomed groove formed by the thermal cutting beam on the material to be cut can be detected.

Further, according to the present invention, a plurality of pressure sensors are arranged on the outer circumference of the heat cutting beam at intervals in the circumferential direction, whereby the pressure distribution on the outer circumference of the heat cutting beam is constantly detected to determine the cutting condition. Monitoring can be done. In this monitoring, the cutting situation can be accurately grasped by calculating the difference between the output levels of the pressure sensors, that is, the difference between the detected pressures detected by the pressure sensors.

Further, according to the present invention, the follow-up means is provided in the nozzle member, and the pressure sensor is always arranged downstream of the nozzle member in the cutting direction so as to follow the cut-off groove. is there.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a partial sectional view of an embodiment of the present invention. In the metal material 1 to be cut, the laser beam 4 is condensed by the lens 5 as the head 2 moves in the cutting movement direction indicated by the arrow 3 along the surface of the material 1 to be cut, The cutting groove 6 is formed and cut.
The laser beam 4 having the same axis is guided to the hollow truncated cone-shaped nozzle member 7 of the head 2. Gas is pressure-fed to the internal space 8 of the nozzle member 7 from the connection end 9, and the gas is jetted onto the material 1 to be cut from the nozzle hole 10 at the tip thereof as indicated by arrows 12 and 13. In this way, the gas is jetted toward the material to be cut 1 along the path of the laser beam 4 and its outer circumference.

FIG. 2 is a horizontal sectional view taken along the section line II-II in FIG. By moving the nozzle member 7 in the cutting movement direction 3 while irradiating the material 1 to be cut with the laser beam 4, a cutting groove 6 is formed in the material 1 to be cut. In order to detect this cutting state, the nozzle member 7 is provided with a pressure sensor 15 via a mounting piece 14. The pressure sensor 15 has a configuration in which the gas injected from the nozzle 10 collides with and is reflected by the material 1 to be cut, and detects the repulsive pressure of the gas.

FIG. 3 is a sectional view of the pressure sensor 15.
A detection cylinder 18 having a detection port 17 is provided in the housing 16 of the pressure sensor 15, and a diaphragm 20 is arranged in a chamber 19 communicating with the detection cylinder 18. The pressure-dependent displacement of the diaphragm 20 in the chamber 19 is detected by the piezoelectric element 21. The piezoelectric element 21 may be made of a material such as PZT (lead zirconate titanate), and detects the amount of deformation of the diaphragm 20 against the spring 31.

FIG. 4 is a sectional view showing the structure of a pressure sensor 22 used in place of the pressure sensor 15 described above. U
A liquid 24 such as mercury or water is stored in the character tube 23, and the detection port 26 of the detection cylinder 25 is arranged toward the cut material 1. The vertical displacement of one end 27 of the liquid 24 in the U-shaped tube 23, which is open to the atmosphere, is optically or magnetically
The pressure of the detection port 26, which is detected by the detection unit 28 and corresponds to the upper and lower positions thereof, can be detected.

FIG. 5 is a sectional view of a pressure sensor 29 which can be used in place of the pressure sensors 15 and 22. This embodiment is similar to the embodiment of FIG. 3 and the corresponding parts bear the same reference numerals. The displacement of the thin film 30 that changes according to the pressure in the room 19 is detected by the piezoelectric element 31.

The pressure sensor 32 having the other structure shown in FIG. 6 also has a structure similar to that of FIG. 5 described above, but in this embodiment, the strain gauge 33 is fixed to the thin film 30 by affixing the strain gauge 33. An electric signal corresponding to the pressure can be obtained.

Referring again to FIGS. 1 to 3, the pressure sensor 1
The nozzle member 7 is arranged on the downstream side in the cutting movement direction 3 of the nozzle member 7 to detect the repulsive pressure of the gas in the vicinity of the cutting groove 6 of the material to be cut 1. The cutting groove 6 is not sufficiently formed, so that the gas from the nozzle 10 is removed from the cutting groove 6 by the reference numeral 1 in FIG.
When the escape of gas downward as shown by 3 becomes worse, the detection pressure detected by the pressure sensor 15 increases.

FIG. 7 shows the output of the pressure sensor 15 over time. The detected pressure detected by the pressure sensor 15 when the cutting groove 6 is formed in the state where the material 1 to be cut is cut using the laser beam 4 is p1,
When the cutting state becomes insufficient, the detected pressure detected by the pressure sensor 15 rises and a waveform 35 indicating an abnormal state is obtained. By discriminating the output level of the pressure sensor 15 as described above, the disconnection state can be known.

FIG. 8 is a block diagram showing the electrical construction of an embodiment having the construction shown in FIGS. 1, 2, 3 and 7. The output of the pressure sensor 15 is given to a processing circuit 36 realized by a microcomputer,
The processing circuit 36 controls the moving means 37 to move the nozzle member 7 in the predetermined cutting movement direction 3 at a constant speed, and at the same time, the nozzle 10 moves from the surface of the material 1 to be cut at a predetermined constant interval. The processing circuit 36 also operates the laser control means 38 to drive the laser source 39 which generates the laser beam 4. Thus, the normal detected pressure p1 in FIG.
When the abnormal detection output waveform 35 higher than the above is detected by the level discrimination in the processing circuit 36, the output energy of the laser source 39 is increased by the laser control means 38,
In this way, it is possible to surely form the cutting groove 6 in the material 1 to be cut and perform the cutting.

FIG. 9 is a sectional view of another embodiment of the present invention. This embodiment is similar to the embodiment of FIG. 1 described above, and corresponding parts bear the same reference numerals. In this embodiment, it should be noted that another pressure sensor 40 is fixed to the nozzle member 7 on the upstream side of the cutting movement direction 3, that is, on the front side.

FIG. 10 is a sectional view taken along the line XX in FIG. The output of the pressure sensor 15 provided on the downstream side in the cutting movement direction 3 is as shown by the line 41 in FIG. 11, and when the normal cutting groove 6 is formed,
The pressure p1 detected by the pressure sensor 15 has a relatively low value, which is similar to the operation described with reference to FIG. 7 above. When the cutting groove 6 is no longer reliably formed, the pressure detected by the pressure sensor 15 rises and a waveform 42 is obtained. On the other hand, the pressure sensor 40 mounted on the downstream side of the nozzle member 7 in the cutting movement direction 3 constantly detects the pressure p2 exceeding the pressure p1 described above, and the output waveform 43 thereof is obtained.

The other structure of the embodiment shown in FIGS. 9 to 11 is similar to that of the above-mentioned embodiment, and the outputs of the two pressure sensors 15 and 40 are the microcomputer shown in FIG. Is provided to the processing circuit 36. FIG. 12 (1) is almost the same as the waveform shown in FIG. 11 described above. The processing circuit 36 is provided for each pressure sensor 1
Subtract the outputs of 5, 40. The output of the pressure sensor 15 is V15, and the output of the other pressure sensor 40 is V40.
Then, the subtraction value ΔV (= V40−V15) is obtained and the calculation of FIG. 12 (2) is performed. Based on the calculated value of FIG. 12 (2), the processing circuit 36 causes the laser control means 38 to output the laser beam from the laser source 39 when the detected pressure detected by the pressure sensor 15 increases. 12 (3). In this way, it becomes possible automatically to reliably form the cutting groove 6 in the material 1 to be cut.

FIG. 13 is a partial sectional view of another embodiment of the present invention. This embodiment is similar to the previous embodiment, and corresponding parts bear the same reference numerals. FIG. 13 corresponds to the drawings of FIGS. 2 and 10 described above. In this embodiment, a plurality (8 in this embodiment) of pressure sensors 45 to 52 are fixed to the nozzle member 7 at equal intervals in the circumferential direction around the upper and lower axes. Other configurations are the same as those in the above-mentioned embodiment.

As shown in FIG. 14A, when one of the pressure sensors 45 to 52 is directly above the cutting groove 6 of the material to be cut 1, the detected pressure is as shown in FIG. It is a low value as indicated by reference numeral 53 in (2), and the pressure detected by the remaining pressure sensors 46 to 52 is high, and therefore the level of the output waveform 54 of those pressure sensors 46 to 52 is high. When the cutting groove 6 is not reliably formed, a waveform 55 corresponding to the high pressure detected by the pressure sensor 45 is derived from the waveform 53.

In the embodiment of FIG. 13, when the nozzle member 7 is moved so that the cutting groove 6 is located between the pressure sensor 45 and the pressure sensor 46 as shown in FIG. The waveform 56 of FIG. 15 (2) is obtained, the waveform 57 is obtained from the pressure sensor 46, and the waveform 58 is obtained from the remaining pressure sensors 47 to 52.
The output level of the pressure sensors 45 and 46 depends on the distance between the pressure sensor 45 and the cutting groove 6, and in this embodiment, the output level of the pressure sensor 45 near the cutting groove 6 is small and the output level of the pressure sensor 46 distant from the cutting groove 6 is small. The output level is high. The cutting groove 6 is calculated by the interpolation calculation of the output levels of the pressure sensors 45 and 46.
It is also possible to calculate and obtain the position in the circumferential direction of. When the cutting groove 6 is not sufficiently formed, a waveform 59 appears on the pressure sensor 45 and the pressure sensor 46.
, A waveform 60 having a variation ΔV2 lower than the variation ΔV1 in the waveform 56 of the waveform 59 is obtained (Δ
V1> ΔV2).

Further, in the embodiment shown in FIGS. 13 to 15, since a plurality of pressure sensors 45 to 52 are used, there is an excellent effect that the starting end 61 and the ending end 62 of the material to be cut 1 can also be detected. To be achieved.

FIG. 16 is a partial cross-sectional view of still another embodiment of the present invention. Sectional line XVII- in FIG.
The cross section viewed from XVII is shown in simplified form in FIG.
Although this embodiment is similar to the embodiment shown in FIG. 9 above, it should be noted that in this embodiment a skirt 62 is fixed to the nozzle member 7, which skirt 62 is formed with an outward flange 63, Pressure sensors 15 and 40 are fixed on the outward flange 63 to detect the repulsive pressure of gas by the surface of the material 1 to be cut. By providing such a skirt 62, the purity of the gas supplied from the connection end 9 is maintained in the vicinity of the position 640 where the laser beam 4 is irradiated, and the entrainment of air is prevented. Therefore, when the gas is an inert gas such as argon and nitrogen, oxidation by air near the cutting position 640 by the laser beam 4 is prevented, and when the gas is pure oxygen, the oxidation of the molten metal is smooth. Can be done.

FIG. 18 is a partial sectional view of a further embodiment of the present invention, and FIG. 19 is a horizontal sectional view of a part thereof. This embodiment is also similar to the above-mentioned embodiment, and corresponding parts bear the same reference numerals. An attachment member 65 is attached to the nozzle member 7 by a bearing 64. A wheel 69 having a rotation axis perpendicular to the axis of the bearing 64 is rotatably provided below the mounting member 65. The width W1 of the wheel 69 is less than the width W2 of the cutting groove 6 (that is, W1> W
It is defined in 2). The cutting width W2 of the cutting groove 6 is, for example, 0.5 mm. The pressure sensor 15 is fixed to the mounting member 65, and its detection port 17 has a straight line 7 that connects the axis of the nozzle member 7, the axis of the bearing 64, and the center line 69a of the wheel 69.
On the straight line 70, the detection port 71 of the pressure sensor 40 fixed to the mounting piece 65 is also provided. Thus, in the embodiment shown in FIGS. 18 and 19, the detection port 1 of the pressure sensor 15 is irrespective of the movement of the nozzle member 7.
7 can reliably detect the repulsive pressure due to the gas near the cutting groove 6 formed by the laser beam 4.

Although in the above-described embodiment, the description has been made mainly on the one having the structure of the pressure sensor 15, the same operation is performed also on the pressure sensors 22, 29, 32 having other structures and the pressure sensors having other structures. To be achieved.

In addition to the laser beam 4, the present invention is broadly applicable in the case of performing thermal cutting of a material to be cut by using a burner using a fuel, for example, a flame such as a gas burner and another heat cutting beam such as plasma. It can be carried out.

[0037]

As described above, according to the present invention, the gas is jetted from the nozzle member to the material to be cut at the outer periphery of the heat cutting beam,
Since the repulsive pressure is detected by the pressure sensor,
Since it has excellent environmental resistance, has no adverse effect of disturbance, and has a simple structure, it is easy to perform maintenance, and many excellent effects such as less malfunction are achieved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along the section line II-II in FIG.

FIG. 3 is a cross-sectional view showing a configuration of a pressure sensor 15.

FIG. 4 is a sectional view showing a configuration of a pressure sensor 22 according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the structure of a pressure sensor 29 according to still another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the structure of a pressure sensor 32 according to still another embodiment of the present invention.

7 is a diagram showing a detection output waveform of the pressure sensor 15. FIG.

8 is a block diagram showing an electrical configuration of the embodiment shown in FIGS. 1 to 3 and 7. FIG.

FIG. 9 is a partial cross-sectional view of another embodiment of the present invention.

10 is a cross-sectional view taken along the section line XX of FIG.

11 is a diagram showing respective output waveforms of the pressure sensors 15 and 40 shown in FIG.

FIG. 12 is a waveform diagram for explaining the operation of the processing circuit 36 that operates in response to the outputs from the pressure sensors 15 and 40.

FIG. 13 is a partial horizontal cross-sectional view of another embodiment of the present invention.

14 is a diagram showing a state in which the pressure sensor 45 detects the cutting groove 6 in the embodiment shown in FIG.

FIG. 15 is a view showing a state in which the cutting groove 6 is located between the pressure sensors 45 and 46 in the embodiment shown in FIG.

FIG. 16 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 17 is a horizontal sectional view taken along the section line XVII-XVII in FIG.

FIG. 18 is a partial cross-sectional view of still another embodiment of the present invention.

19 is a cross-sectional view taken along the section line IX-IX in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cut material 2 Processing head 3 Cutting movement direction 4 Laser beam 5 Condensing lens 6 Cutting groove 7 Nozzle member 10 Nozzle 15, 22, 29, 32, 40, 45-52 Pressure sensor 36 Processing circuit 37 Moving means 38 Laser source Control means 39 Laser source

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01L 7/08

Claims (4)

[Claims] 1. A cutting state monitoring device for a thermal cutting device which irradiates a material to be cut with a thermal cutting beam while moving in a cutting movement direction to thermally cut the material, and injects gas onto the material to be cut at the outer periphery of the cutting beam. A cutting state monitoring device for a thermal cutting device, comprising a nozzle member and a pressure sensor for detecting a repulsive pressure of gas from a material to be cut. 2. The cutting state monitoring device for a thermal cutting device according to claim 1, wherein the pressure sensor is arranged on the downstream side in the cutting movement direction. 3. The cutting condition monitoring device for a thermal cutting device according to claim 2, wherein the nozzle member is provided with a follow-up means for holding the pressure sensor and locating the pressure sensor on the downstream side in the cutting movement direction to follow the pressure sensor. . 4. The heat sensor according to claim 1, wherein a plurality of pressure sensors are provided at intervals in the circumferential direction, and a difference in output level between the pressure sensors is calculated to monitor the disconnection state. Cutting condition monitoring device for cutting device.