JPH04356395A - Laser beam machine - Google Patents

Abstract

PURPOSE:To accurately execute the gas pressure control and to improve the working accuracy, even if set pressure of a regulator is low. CONSTITUTION:To the inside of a duct line 7, a regulator 11 for adjusting pressure of supply gas, based on an external command is connected. Between a nozzle 4 and the regulator 11 in the duct line 7, a solenoid valve 14 is connected, and a variable throttle valve 15 is connected to the duct line 7 so as to become parallel to its solenoid valve 14. This machine is provided with a pressure sensor 6 for detecting pressure of gas injected from the nozzle 4, and a controller 18 for inputting a pressure detect signal of its pressure sensor 6 and applying feedback control to the regulator 11. In the case command pressure from the outside is <=0.8kg/cm<2>, the solenoid valve 14 is subjected to closing control by a comparator 17. In the case the pressure is larger than 0.8kg/cm<2>, the solenoid valve 14 is subjected to opening control by the comparator 17.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing machine, and more particularly to control of gas pressure of assist gas, etc. supplied to a nozzle.

0002

[Prior Art] In this type of laser processing machine, a laser beam is emitted from the tip of a nozzle toward the workpiece, and gas such as assist gas is ejected to cut the workpiece. ing. in this case,
The pressure of the gas ejected from the nozzle is set and adjusted to the optimum pressure according to processing conditions such as the material and thickness of the workpiece.

The pressure of the gas supplied to the nozzle is regulated by a regulator such as an electro-pneumatic regulator, and the pressure of the gas discharged from the regulator is determined by a gas pressure command from a controller such as an NC device. It is set based on.

0004

[Problem to be Solved by the Invention] However, in normal regulators, pressure control in the low pressure region is unstable;
As shown in Figure 2, in a typical regulator, the pressure (secondary pressure) of the gas discharged from the regulator is approximately 0.5~
If it is less than 0.8 Kg/cm2, the discharge pressure cannot be kept constant, and stable laser processing cannot be performed, resulting in a decrease in processing accuracy.

The present invention has been made to solve the above problems, and its purpose is to be able to accurately control gas pressure and improve machining accuracy even if the set pressure of the regulator is low. The object of the present invention is to provide a laser processing machine that can be improved.

[0006]

[Means for Solving the Problems] In order to achieve the above object, in the first invention, a laser beam focused by a lens is emitted to a workpiece, and an assist gas etc. supplied inside the workpiece is emitted. A nozzle that ejects gas to the workpiece, a regulator that is connected to the gas pipeline supplied to the nozzle and adjusts the pressure of the supplied gas based on an external command, and a link between the nozzle and the regulator. A solenoid valve connected to a conduit to open and close the conduit, a throttle valve connected to the conduit in parallel with the solenoid valve, and when a command pressure input to the regulator is greater than a predetermined value. control means for opening the solenoid valve and controlling the operation of the regulator so that the secondary pressure of the regulator is equal to or higher than a predetermined value when the command pressure is less than a predetermined value, and for closing the solenoid valve. , the gas supplied from the regulator to the nozzle passes through the solenoid valve when the command pressure input to the regulator is greater than a predetermined value, and the gas passes through the throttle valve when the command pressure is less than the predetermined value. It is.

In the second aspect of the invention, the control means includes a detector that detects the pressure of the gas ejected from the nozzle, and a controller that inputs a detection signal from the detector to feedback control the regulator. .

[0008]

[Operation] Therefore, according to the present invention, when the command pressure from the outside is less than a predetermined value, the solenoid valve is closed by the control means, and the gas supplied from the regulator to the nozzle passes through the throttle valve to reduce the pressure. Ru. The pressure of the gas ejected from the nozzle is detected by a detector, and the detection signal is input to the controller. Then, the controller performs feedback control of the regulator so that the detected pressure matches the command pressure, and the secondary pressure of the regulator becomes equal to or higher than a predetermined value. Therefore, when the command pressure from the outside is below a predetermined value, gas with a pressure above the predetermined value is discharged from the regulator, so there is no need to perform pressure control in a low pressure range, and stable pressure control can be performed. can.

Further, when the command pressure from the outside is higher than a predetermined value, the solenoid valve is opened by the control means, and the gas discharged from the regulator is supplied to the nozzle without passing through the throttle valve.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings. As shown in FIG. 1, the nozzle holder 1
has a lens 2 fitted and supported therein for condensing laser light, and a nozzle 4 having a spout 3 at the tip at the bottom thereof.
is supported by screws. Gas supply port 5 is connected to nozzle holder 1
An opening is formed in one side wall of the nozzle 4 and communicates with the internal space of the nozzle 4 . A pressure sensor 6 as a detector is attached to the side wall of the nozzle 4 so as to face the internal space of the nozzle 4.

One end of the pipe line 7 is connected to the gas supply port 5 of the nozzle holder 1, and the other end is connected to three electromagnetic valves 8, 9, and 10 connected in parallel with each other. Oxygen, air, nitrogen, etc. are usually used as assist gas.
These assist gases are each housed in a gas supply section (not shown). Each gas supply section has each solenoid valve 8.
, 9, and 10, and each electromagnetic valve 8, 9, and 10 is selectively opened and closed by a switching command from a controller of an NC device (not shown), and required assist gas is sent to the pipe line 7.

A regulator 11 made of an electropneumatic regulator or the like is connected to the conduit 7. The controller 18 is built in the regulator 11, and this controller 18 receives a gas pressure command signal from the controller, and based on the gas pressure command signal, the supplied assist gas is adjusted to a required pressure and discharged. Controls the operation of the regulator 11. Further, the controller 18 is electrically connected to the pressure sensor 6 via an analog latch circuit 16. Then, the pressure signal detected by the pressure sensor 6 is transmitted to the analog latch circuit 16.
is fed back to the controller 18 via the controller 1
8 performs feedback control on the regulator 11 so that the pressure detected by the pressure sensor 6 matches the command pressure.

A direct-acting solenoid valve 12 for opening/closing switching is connected to the pipe 7 between the nozzle holder 1 and the regulator 11, and a direct-acting solenoid valve 12 for non-return is connected to the output side of the solenoid valve 12. A valve 13 is connected with its output side facing the solenoid valve 12. Both electromagnetic valves 12 and 13 are opened and closed simultaneously by a switching command from the controller. A direct-acting solenoid valve 14 is connected to the pipe line 7 between the regulator 11 and the direct-acting solenoid valve 12, and a variable throttle valve 15 is connected to the pipe line 7 in parallel with the solenoid valve 14. ing.

The comparator 17 controls the opening and closing of the direct acting solenoid valve 14 based on the pressure command. That is, in this embodiment, the comparator 17 has an input command pressure of 0.8 kg/
cm2 or less, the solenoid valve 14 is closed and 0.8
If it is larger than Kg/cm2, the solenoid valve 14 is controlled to open. In this embodiment, the pressure sensor 6, controller 18 and comparator 17 constitute a control means.

A piercing gas pipe 19 is connected between the input side pipe of the electromagnetic valve 8 and the gas supply port 5, and oxygen as a piercing gas is supplied into the nozzle 4 through this pipe 19. Ru. A regulator 20 such as an electro-pneumatic regulator is connected to this conduit 19. A controller 23 built into the regulator 20 receives a gas pressure command signal from the controller, and adjusts the pressure of the supplied piercing gas based on the command signal to a required pressure before discharging the regulator 20. control the operation of A direct acting solenoid valve 21 for opening/closing switching is connected to the pipe line 19 between the nozzle holder 1 and the regulator 20, and a direct acting solenoid valve 22 for checking is connected to the output side of the solenoid valve 21. It is connected with its output side facing the solenoid valve 21. Both electromagnetic valves 21 and 22 are opened and closed simultaneously by a switching command from the controller.

Note that when the piercing operation is started after the end of the assist operation, the analog latch circuit 16 controls the pressure sensor 6 immediately before the end of the assist operation.
This is to hold the assist gas pressure detection signal from the assist gas until the start of the next assist operation. In other words,
If the assist operation is started after the piercing operation ends, the regulator 11 is activated at the start of the assist operation.
Since the detection signal of the pressure sensor 6 that is fed back is the pressure detection signal of the piercing gas just before the end of the piercing operation, accurate pressure control cannot be performed immediately after the start of the assist operation. However, by providing the analog latch circuit 16, it is possible to can be prevented.

Next, the operation of the laser processing machine configured as described above will be explained. Now, in the laser processing machine of this embodiment, based on a command from the controller, the direct-acting solenoid valves 21 and 22 for opening/closing switching and checking in the piping gas pipe 19 are simultaneously opened and operated. ,
Similarly, based on a set pressure command input from the controller, the regulator 20 adjusts the pressure of the supplied piercing gas to the set pressure and discharges it. Piercing gas is then supplied into the nozzle 4 from the gas supply port 5 via the conduit 19. Then, the supplied piercing gas is ejected from the ejection port 3 onto the workpiece (not shown), and the laser beam focused by the lens 2 is also emitted from the ejection port 3 toward the workpiece, causing the workpiece to be pierced in a predetermined manner. will be held. At this time, even if a portion of the piercing gas flows back into the assist gas pipe 7, the backflow is completely prevented by the reverse direct-acting electromagnetic valve 13 in the closed state.

When the piercing is completed, both the electromagnetic valves 21 and 22 are simultaneously closed based on a command from the controller, and then, based on a command from the controller, the opening/closing switching and Direct-acting electromagnetic valves 12 and 13 for check are simultaneously opened, and electromagnetic valves 8, 9, and 10 are selectively opened, and the required assist gas is sent to conduit 7. and,
Similarly, based on a set pressure command input from the controller, the regulator 11 adjusts the pressure of the supplied assist gas to the set pressure and discharges the assist gas.

[0019] Here, the commanded set pressure is 0.8 kg.
/cm2, the direct-acting solenoid valve 14 is controlled to open by the comparator 17, and the assist gas is supplied from the gas supply port 5 into the nozzle 4 through the solenoid valve 14 without passing through the variable throttle valve 15. Ru. Then, the supplied assist gas is ejected from the ejection port 3 toward the workpiece (not shown), and the laser beam focused by the lens 2 is also emitted from the ejection port 3 toward the workpiece, so that a predetermined laser beam is applied to the workpiece. Processing is performed. At this time, even if a part of the assist gas flows back into the piping gas pipe 19, the back flow is completely prevented by the reverse direct-acting electromagnetic valve 22 in the closed state.

At this time, the pressure of the assist gas ejected from the nozzle 4 is constantly detected by the pressure sensor 6, and the detection signal of the pressure sensor 6 is fed back to the controller 18 of the regulator 11. And controller 1
8, the regulator 1 is controlled so that the pressure detected by the pressure sensor 6 matches the command pressure from the controller.
The discharge pressure of assist gas from 1 is automatically controlled.

Therefore, for example, when pressure fluctuations occur due to changes in the gap between the tip of the nozzle 4 and the workpiece, or when the command pressure to the regulator 11 is increased or decreased as shown in FIG. The same regulator 11
Even if an error ΔP occurs due to hysteresis in the secondary pressure of Since the gas supply amount is controlled so that the pressure is always maintained at the set pressure, laser processing can be performed with high precision.

If the set pressure commanded by the controller is 0.8 kg/cm2 or less, the comparator 17 closes the direct-acting solenoid valve 14, and the assist gas passes through the variable throttle valve 15 to the nozzle 4. supplied within. Here, assuming that the flow rate ratio of the variable throttle valve 15 is set to 10:1, the pressure of the assist gas ejected from the nozzle 4 will be approximately one-tenth of the set pressure. When the pressure inside the nozzle 4 is detected by the pressure sensor 6 and the detection signal is fed back to the controller 18 of the regulator 11, the controller 18 converts the pressure detected by the pressure sensor 6 into the command pressure from the controller. The discharge pressure of the assist gas from the regulator 11 is increased approximately 10 times to match the above.

In other words, from the controller to the regulator 1
When the set pressure commanded for 1 is low pressure, the pressure of the assist gas supplied to the nozzle 4 is made lower than the discharge pressure of the regulator 11 by the variable throttle valve 15,
By feedback-controlling the regulator 11 so that the pressure inside the nozzle 4 becomes the set pressure, the pressure of the assist gas discharged from the regulator 11 can be increased as a result. Therefore, even when ejecting low-pressure assist gas from the nozzle 4, the discharge pressure from the regulator 11 can be increased to a pressure range in which the pressure control characteristics of the regulator 11 are good, and stable pressure control can be performed. Laser processing using low-pressure assist gas can also be performed with high precision. Therefore, it is possible to adjust the assist gas to the optimal pressure depending on the machining conditions such as the material and thickness of the workpiece, and it is also possible to perform stable pressure control in any pressure range, making it possible to control the laser with high precision. It is possible to perform machining, and the degree of freedom in machining various types of workpieces can be increased. Furthermore, as shown in FIG. 2, even if an error ΔP occurs due to hysteresis in the secondary pressure of the regulator 11 when the command pressure to the regulator 11 is increased or decreased, no pressure is ejected from the nozzle 4. Since the pressure of the reduced assist gas and its error ΔP are reduced to approximately one-tenth, it can contribute to improving the machining accuracy.

It should be noted that the present invention is not limited to the above embodiment, and for example, the flow rate ratio of the variable throttle valve 15 may be changed as appropriate. Further, as shown by the chain line in FIG. 2, a direct-acting electromagnetic valve 24 and a variable throttle valve 25 are provided in the piping line 19 for the piercing gas, so that the same pressure control as that for the assist gas can be performed for the piercing gas as well. It may be configured to do so. In this case, it is necessary to provide an analog latch circuit, a comparator, and a controller similarly to the assist side.

[0025]

As described in detail above, according to the present invention, when the set pressure of the regulator is low, the pressure of the gas supplied to the nozzle is made lower than the discharge pressure of the regulator by the variable throttle valve, By controlling the regulator in feedback so that the pressure inside the nozzle reaches the set pressure, the pressure of the gas discharged from the regulator can be increased to the pressure range where the pressure control characteristics of the regulator are good. Even if the pressure of the gas supplied to the nozzle is low, it exhibits the excellent effect of being able to accurately control the gas pressure and improving processing accuracy.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a laser processing machine embodying the present invention.

FIG. 2 is a diagram showing the relationship between the command pressure from the controller and the secondary pressure of the regulator, and the relationship between the secondary pressure and the pressure reduced by the variable throttle valve.

[Explanation of symbols]

2 lens, 4 nozzle, 6 pressure sensor as a detector constituting control means, 7 pipe line, 11 regulator, 14 direct acting solenoid valve, 15 variable throttle valve, 17 comparator constituting control means, 18 also control A controller constituting the means.

Claims (2)

[Claims] 1. A nozzle for emitting a laser beam focused by a lens onto a workpiece and ejecting a gas such as an assist gas supplied thereinto the workpiece; A regulator that is connected to a gas pipeline and adjusts the pressure of the supplied gas based on an external command; a solenoid valve that is connected to a pipeline between the nozzle and the regulator that opens and closes the pipeline; and the solenoid valve. a throttle valve connected to the conduit in parallel with the solenoid valve, which opens the solenoid valve when the command pressure input to the regulator is greater than a predetermined value, and opens the solenoid valve when the command pressure is less than the predetermined value; control means for controlling the operation of the regulator so that the next side pressure is equal to or higher than a predetermined value, and closing the solenoid valve, and when the command pressure input to the regulator is greater than the predetermined value, the regulator supplies it to the nozzle. gas passes through the solenoid valve,
A laser processing machine characterized in that the gas is configured to pass through the throttle valve when the command pressure is below a predetermined value. 2. The control means includes a detector that detects the pressure of the gas ejected from the nozzle, and a controller that inputs a detection signal from the detector to feedback control the regulator. laser processing machine.