JPH0563272B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a processing head position control device in a laser processing apparatus.

[Technical Background of the Invention and Problems Therewith] A laser processing apparatus is generally provided with a device that adjusts the position of a processing head so that the laser beam is focused on a predetermined position on a workpiece.
However, with the processing head position adjustment device in such conventional laser processing equipment, once the workpiece is set on the processing table and the position of the processing head is adjusted to determine the focus of the laser beam, the workpiece is It does not move up or down, and is designed to maintain a constant focus position until the next processing head position change signal is received.

However, in the case of such a processing head position control device, even if the material to be processed is wide like sheet metal and there are waves in the middle, the position will always be fixed at a predetermined position regardless of changes in the material to be processed. There were cases in which the focus remained fixed at the position and shifted, making it impossible to obtain good cutting.

[Purpose of the Invention] The present invention was made in view of the above-mentioned problems in the prior art. The present invention provides a processing head position control device for a laser processing device that controls the clearance to the surface of a workpiece to always be constant, thereby ensuring good laser processing.

[Summary of the Invention] The present invention provides a processing head having a laser irradiation hole and a gas injection hole for irradiating a laser beam onto the processing material and injecting an assist gas so as to be able to move toward and away from the processing material, A plurality of detection holes are provided around the assist gas injection hole to detect the reflected pressure of the assist gas, and the detected reflected pressure is compared and calculated with a reference pressure value, and the position of the processing head is determined according to the pressure difference. A processing head position control device for a laser processing device, characterized in that it is equipped with a position control device for controlling the laser processing head. This system calculates the clearance between the irradiation hole and the surface of the workpiece, and controls the position of the processing head so that the clearance is always constant, allowing for good laser processing.

[Embodiment of the Invention] FIG. 1 shows a cross section of a processing head according to an embodiment of the invention, and FIG. 2 shows a circuit block diagram of a position control device for the processing head. The processing head 1 is composed of a telescopic mechanism section 3, a head rotation mechanism section 5, an air servo mechanism section 7, a lens mount section 9, an assist gas supply section 11, and a nozzle section 13.

The telescopic mechanism 3 is a part that blocks dust from entering from the outside air and allows the processing head 1 to move up and down.

The head rotation mechanism section 5 is constituted by a worm gear reduction device, and is for providing low speed rotation so that the seal section 17 of the air servo cylinder 15 and the inner surface of the cylinder 15 are always in contact with each other with a coefficient of dynamic friction. It is. The head rotation mechanism 5 minimizes hysteresis during operation of the air servo cylinder 15, allowing operation even with minute air pressure.

The air servo mechanism section 7 includes an air servo cylinder 15
This is the part that moves the processing head 1 up and down due to the pressure difference between the first chamber 19 and the second chamber 21 in the air supply port 23 and the feedback air supply port 25 to the first chamber 19 and the second chamber 21, respectively. By supplying air to the machining head 1, the vertical position of the machining head 1 is adjusted.

A bearing 27 and a ball bush 29 are provided in the lens mount section, and the air servo cylinder 1
The shaft 31 is used as a guide to move the entire machining head 1 up and down. A lens 33 for condensing a laser beam is attached to this lens mount portion 9 .

The assist gas supply section 11 is provided with an assist gas supply port 35 through which assist gas is introduced into the processing head 1 .

The nozzle part 13 is screwed and attached to the assist gas supply part 11, and has a gas injection hole/laser beam irradiation hole 37 in the center, and four sensing ports as reflective pressure detection holes around it. 39 are provided.

A laser beam introduced from a laser oscillator (not shown) passes through the center of the processing head 1 in FIG. irradiated on top.

Further, the assist gas supplied from the assist gas supply port 35 is supplied to the processed material W from the gas injection hole 37.
It is injected upward and has the effect of blowing away the melted material caused by the laser beam.

Electrical processing of the reflected pressure from the sensing port 39 of the assist gas from the processing material is performed based on FIG. In other words, the reflected pressure of the assist gas injected from the gas injection hole 37 is obtained by amplifying the reflected pressure obtained through each sensing port 39 by the amplifiers 41a, b, c, d, and then by the pressure sensor 43a, b, c, d. and input it to the amplifier 45. The amplifier 45 supplies the detected pressures from the pressure sensors 43a, b, c, and d to the microprocessor 47 as analog quantities.

In the microprocessor 47, each pressure sensor 43
Among the pressure values a, b, c, and d, only the maximum pressure value is taken as the accurate sensing pressure, and that pressure is compared with the reference pressure to calculate the necessary adjustment value of the processing head. The calculated values are the amplifiers 49a, b, c.
It is given as a control signal to the pressure-type electropneumatic proportional valves 51a, b, and c of the air servo mechanism section 7 through the control signal.

The electro-pneumatic proportional valves 51b and 51c are for controlling the amount of compressed air supplied to the first chamber 19 and the second chamber 21 of the air servo cylinder 15, respectively. 15. In addition,
Power is supplied from a constant voltage power supply device 53 to each amplifier 45 and amplifiers 49a, b, and c.

In the above embodiment, the reflected pressure sensing port 39 is used as a gas injection hole and a laser beam irradiation hole 3.
The reason why four locations were provided around 7 is as follows. In other words, as shown in FIG. 3, when there is a cutout 55 or a cutout 57 in the vicinity of the laser processing part of the workpiece W, the reflected pressure of the assist gas is
5 and the cutting section 57, only small values are obtained.
It is sensed that the apparent clearance is extremely large with respect to the portion 59 where actual laser cutting is performed. Therefore, this cutout portion 5
If the position control is performed using the reflected pressure of the cutting portion 5 or the cutting portion 57, accurate position control will not be possible. Therefore, a plurality of ports 39a, b, c,
d, and only the maximum reflected pressure among them is adopted as an accurate sensing pressure, and the reflected pressure is compared with a reference pressure value to control the position of the processing head.

The operation of the processing head position control device in the above laser processing apparatus will now be described. The focus of the laser beam on the workpiece W is adjusted using the first air servo cylinder 15 in the air servo mechanism section 7.
Air supply ports 23 are provided in the chamber 19 and the second chamber 21, respectively.
Adjust up or down depending on the amount of compressed air supplied through 25. At this time, the processing head 1 is constantly rotated by the head rotation mechanism 5 so that the air cylinder 15 can respond to minute fluctuations in air pressure, so that static friction does not act on the air servo cylinder 15. do. In this way, the laser beam passes through the center of the processing head 1 and is focused by the focusing lens 33, and is irradiated onto a predetermined position on the workpiece W to cut that portion. The assist gas supplied from the supply port 35 in the assist gas supply section 11 is injected onto the workpiece W from the assist gas injection hole 37, and blows away the portion melted by the laser beam.

Here, the reflected pressure of the assist gas that hits the workpiece W and is reflected is introduced into each reflected pressure sensing port 39, and the reflected pressure is constantly sensed by pressure sensors 43a, b, c, and d during laser processing. do.

When the reflected pressures obtained by the pressure sensors 43a, b, c, and d are separated from the reference pressure value given as the pressure value obtained at the optimum clearance, the microprocessor 47 calculates the difference. gives a control signal to the amplifiers 49a, b, c to move the machining head 1 in the direction of decreasing or increasing the clearance;
The pressure-type electropneumatic proportional valves 51a, b, and c are controlled to drive the air servo cylinder 15 in a desired direction to adjust the position of the processing head 1.

In the above embodiment, the reflected pressure sensing ports 39 are provided at four locations, but the positions and number of these ports are not limited, and a plurality of ports can be provided at desired locations as necessary.

[Effects of the Invention] This invention provides a plurality of detection holes for detecting the reflected pressure of the assist gas around the assist gas injection hole, compares the detected pressure with a reference pressure value, and calculates the detected pressure according to the pressure difference. Since the position of the processing head is controlled by laser processing, even if the surface of the processing material is wavy and the clearance between the tip of the processing head and the nozzle changes during laser processing, the change in clearance will be avoided. The position of the machining head can be controlled in accordance with this, and good laser machining can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a circuit block diagram of the embodiment, and FIG. 3 is an explanatory diagram of the operation of the embodiment. 1... Processing head, 7... Air servo mechanism section,
9... Lens mount section, 11... Assist gas supply section, 13... Nozzle section, 15... Air servo cylinder, 19... First chamber, 21... Second chamber, 3
3... Focusing lens, 35... Assist gas supply port, 37... Gas injection hole and laser beam injection hole,
39...Reflection pressure sensing port.

Claims (1)

[Claims] 1. A processing head having a laser irradiation hole and a gas injection hole for irradiating the workpiece with a laser beam and injecting assist gas is provided so as to be able to move toward and away from the workpiece, and a processing head is provided around the assist gas injection hole. In addition to providing multiple detection holes to detect the reflected pressure of the assist gas, a position control device is installed that compares and calculates the detected reflected pressure with a reference pressure value and controls the position of the processing head according to the pressure difference. A processing head position control device in a laser processing device, characterized in that: