JPH069755Y2 - Nozzle attitude angle detector for laser processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a nozzle attitude angle detection device applied to a laser processing machine.

[Conventional technology]

In the laser processing machine disclosed in JP-A-60-72692, a plurality of light beams are emitted from a nozzle so as to intersect in front of the surface of the workpiece, and an irradiation spot of these light beams on the surface of the workpiece is imaged. The nozzle attitude angle is detected by imaging with the device and processing the image of the spot obtained thereby.

[Problems to be solved by the invention]

The conventional technique described above has the following problems.

) Since the optical system such as the image pickup means and the image processing means are required, the processing machine itself becomes large and the cost becomes high.

ii) Complex adjustments such as optical path adjustment of the optical system are required.

iii) Since image processing is performed, it takes time to obtain a detection result. Therefore, when correcting the attitude angle of the nozzle based on the detection result, control is delayed.

iv) Since the optical system is arranged in the vicinity of the tip of the nozzle, the optical system is an obstacle and it is not possible to bring the nozzle to a narrow space of the workpiece.

[Means and Actions for Solving Problems]

The present invention is made in order to solve the above-mentioned conventional problems, and is provided symmetrically with respect to the central axis of the nozzle that discharges the assist gas, and controls the pressure of the assist gas discharged from each of the nozzle tips. A pair of pressure detecting means for detecting and a nozzle attitude angle detecting means for detecting an attitude angle of the nozzle with respect to the upper surface of the workpiece based on the output of the pressure detecting means.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a sectional view of a processing head of a laser processing machine to which the present invention is applied.

In the figure, the processing head 1 has rotating shafts 2, 3 and 4 in the θ ₁ , θ ₂ and θ ₃ directions. Then, inside thereof, reflecting mirrors 6 and 7 for guiding the laser light L emitted from a laser oscillator (not shown) to the nozzle 5 are arranged at an angle of 45 degrees.

The nozzle 5 includes a lens 8 that collects the laser light L,
A supply port 9 for assist gas (for example, oxygen, air, nitrogen, etc.) is provided.

The laser beam L focused by the lens 8 is focused on the upper surface 10a of the workpiece 10 and the assist gas is blown to the processing point. As a result, processing such as cutting is performed on the workpiece 10. At this time, in order to optimize the processing accuracy and efficiency, the central axis of the nozzle 5
₁ and the normal ₂ of the upper surface 10a of the workpiece 10 are required to coincide with each other.

Here, the principle of detecting the angle θ formed by the central axis ₁ of the nozzle 5 and the normal ₂ of the processed surface 10a of the workpiece 10 will be described.

As shown in FIG. 3, in general, a fluid that has entered a curved pipe from a straight pipe is subjected to centrifugal force at the curved portion, so that the pressure of the fluid is high (to a positive pressure) outside the curved portion and low inside ( Negative pressure), and its size increases as the bend becomes tighter.

The positions A and B on the tip surface of the nozzle 5 shown in FIG.
It is set to be symmetrical with respect to the axis ₁ of the nozzle. Now, as shown in FIG.
0a when the nozzle 5 is positioned vertically (θ
= 0), the gas discharged from the nozzle flows along a flow path equivalent to the above-mentioned pipe as indicated by the arrow, and thus negative pressure is generated at the positions A and B. Further, in the case of the same figure, since the left and right flow paths are symmetrical, the gas pressures at the positions A and B become equal.

Next, as shown in FIG.
On the other hand, when the nozzle 5 has the posture angle θ, the negative pressure increases at the point A in proportion to the posture angle θ,
The negative pressure decreases at the point B. At this time, points A and B P _A ,
P _B is expressed by the following equations (1) and (2).

P _A = −Kθ + P ₀ (1) P _B = Kθ + P ₀ (2) where K; proportional constant P ₀ ; pressure of P _A and P _B when = 0 Therefore, the nozzle attitude angle θ is From the above equations (1) and (2), it is represented by the following equation (3).

_{θ = P A -P B / -2K} ...... (3) Figure 1 shows an embodiment of the present invention based on the principle described above.

In the figure, at the tip of the nozzle 5, gas introduction passages 11 and 12 are provided symmetrically with respect to the central axis _{1 of the} nozzle. The tip of each passage 11 and 12 is a nozzle 5
Open at positions A'and B'on the distal end surface of the tube and the proximal ends of their passages 11, 12 are tubes 13 and 1, respectively.
It is connected via 4 to pressure sensors 15 and 16.

Further, in the nozzle 5, gas introduction passages 17 and 18 are provided symmetrically like the passages 11 and 12. The tips of these passages 17 and 18 open at the positions A ″ and B ″ of the nozzle tip surface, respectively, and the base ends thereof are connected to the pressure sensors 21 and 22 via tubes 19 and 20, respectively. .

FIG. 5 is a bottom view of the nozzle 5, and the nozzle cross sections shown in the upper and lower parts of FIG. 1 are aa of FIG. 5, respectively.
It is a cross section and a bb cross section. The aa direction in FIG. 5 indicates the left-right direction in FIG. 2, and the bb direction indicates the direction perpendicular to the paper surface in the same figure.

The output signals of the sensors 15 and 16 indicating the gas pressures P _A ′ and P _B ′ at the positions A ′ and B ′ are applied to the calculator 25 via amplifiers 23 and 24, respectively. The computing unit 25 executes the computation of the equation (3), and thereby the attitude angle θ ₁ of the nozzle 5 with respect to the upper surface 10a of the workpiece 10 is detected.

Also, the gas pressure P _A ″ at the positions A ″ and B ″
The output signals of the sensors 21 and 22 indicating P _B ″ and P _B ″ are supplied to an arithmetic unit 28 via amplifiers 26 and 27, respectively.
Added to. The computing unit 28 executes the computation of the equation (3), and thereby the attitude angle θ ₂ of the nozzle 5 with respect to the upper surface 10a of the workpiece 10 is detected. The posture angles θ ₁ and θ ₂ calculated by the calculators 25 and 28
Are respectively displayed on the display 29.

Furthermore, the computing unit 30 executes the computation of the following equation (4) to obtain the average pressure P of the gas pressures at the positions A ′, B ′, A ″ and B ″.

P = P _A ′ + P _B ′ + P _A ″ + P _B ″ / 4 (4) In the comparator 31, the average pressure P obtained by the calculator 30 is the reference pressure P preset in the setting machine 32. is compared to _r . The reference pressure P _r is a threshold value for determining whether the nozzle 5 and the workpiece 10 are too far apart or whether the workpiece 10 is present at the tip of the nozzle 5, If the comparator 32 has P ≦ P _r ,
That is, an alarm signal is generated when the workpiece is too far away or the workpiece is not present. This alarm signal is applied to drive the alarm device 33, emergency stop of laser light, and the like.

The nozzle attitude angles θ ₁ and θ ₂ in the above-described embodiment can be used for checking the nozzle attitude angle with respect to the workpiece during teaching and for controlling the nozzle attitude angle correction during machining such as cutting.

In the above embodiment, the nozzle 5 is used to detect the gas pressure.
The passages 10, 11, 16 and 17 were formed in the
As shown in the figure, the tubes 34, 3 are provided on the side of the nozzle.
5 may be provided, and the tips of these tubes 34, 35 may be made to face the nozzle tip surface to detect the pressure.

Further, in the above-described embodiment, the nozzle attitude angles θ ₁ and θ in two directions based on the pressures at four points A ′, B ′, A ″ and B ″.
_{Although 2} is detected, it is also possible to improve the measurement accuracy by increasing the number of pressure measurement points.

[Effect of device]

As described above, according to the present invention, the attitude angle of the nozzle can be detected by detecting the pressure of the assist gas. Therefore, it is possible to solve all of the above-mentioned problems i) to iv) of the conventional device that detects the attitude angle using the image pickup means or the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a nozzle attitude angle detecting device of a laser processing machine according to the present invention, FIG. 2 is a sectional view of a processing head portion of the laser processing machine, and FIG. 3 is pressure in a bent pipe. FIG. 4 is a view showing the distribution, FIGS. 4 (a) and 4 (b) are views showing the state of releasing assist gas, FIG. 5 is a bottom view of the nozzle according to the embodiment, and FIG. 6 is another view of the present invention. It is the figure which showed the Example. 1 ... Machining head, 2, 3, 4 ... Rotating shaft, 6, 7 ... Reflecting mirror, 8 ... Lens, 9 ... Supply port, 10 ... Workpiece, 10a
... top surface, 11, 12, 17, 18 ... passage, 13, 14,
19, 20 ... Tube, 15, 16, 21, 22 ... Pressure sensor, 23, 24, 26, 27 ... Amplifier, 25, 28
... Calculator

Claims (1)

[Scope of utility model registration request] 1. A laser processing machine comprising a nozzle for emitting an assist gas and laser light toward a workpiece from a tip opening, the laser processing machine being provided symmetrically with respect to the central axis of the nozzle, each from the tip of the nozzle. The attitude angle of the nozzle with respect to the upper surface of the workpiece is detected based on the difference between the pressure detected by the pair of pressure detection means for detecting the pressure of the assist gas released and the pressure detected by the pair of pressure detection means. A nozzle attitude angle detection device in a laser beam machine, comprising: a nozzle attitude angle detection means.