JPH0230388A - Laser beam cutting method - Google Patents

Abstract

PURPOSE:To prevent defective cutting and to improve cutting efficiency by increasing the cutting speed by stages at the time of starting cutting when the cutting speed is shifted from an unstationary state to a stationary state and at work corner parts. CONSTITUTION:A laser beam 2 oscillated from a laser beam oscillator 1 is led to a machining head 4 and while assisting gas from an assisting gas feeder 8 being regulated, a work 7 is cut. At this time, at the time of starting cutting after piercing the work 7 and at points (b)-(f) of the corner parts of the work 7, an NC device 16 is controlled to execute setting so that a speed command signal is increased by stages from a value of 10%, etc., of the stationary speed and the speed of 100% is attained when the cutting speed gets to the stationary state. Since the cutting speed is increased by stages at the cutting starting point and the rise points of the corner parts, blowing-up at the time of cutting is prevented. Since the cutting speed is increased, the occurrence of defective cutting is prevented and cutting efficiency is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser cutting method for cutting a workpiece such as a plate using a laser beam.

[Conventional technology]

Conventionally, when using a laser processing machine to cut a workpiece such as a plate, the workpiece is cut by irradiating the workpiece with a laser beam while ejecting assist gas from the processing head, and the cutting speed is controlled by an NC device. Ru.

[Problem to be solved by the invention]

However, in the conventional cutting method described above, the acceleration/deceleration of the cutting speed is set to an optimum value by a control system or a mechanical system.

For this reason, the acceleration/deceleration is not optimal for the thickness of the workpiece, especially when working with thick plates made of aluminum or stainless steel, at the time of transition from an unsteady state to a steady state, such as when starting cutting or corner machining. There was a problem in which the molten material blown up during the rise of time, resulting in poor cutting.

Furthermore, in order to prevent the above-mentioned problems, conventionally cutting has been performed at a slow cutting speed, which has led to problems such as poor work efficiency.

The present invention has been made to improve the above-mentioned problems, and it is an object of the present invention to provide a laser cutting method that prevents the blow-up that occurs when the cutting speed changes from an unsteady state to a steady state.

[Means and effects for solving the problem] In order to achieve the above object, the present invention provides a laser cutting method for cutting a workpiece using a laser beam and an assist gas.
By increasing the cutting speed step by step at the start of cutting when the cutting speed transitions from an unsteady state to a steady state, or at the rise of a corner where the cutting direction has been changed, it is possible to prevent cutting defects due to blistering. , the steady cutting speed has been increased to enable high-speed cutting.

In addition, by setting the cutting time stepwise to an optimal value according to the material and thickness of the workpiece, we provide a laser cutting method that facilitates cutting of difficult-to-cut materials and cutting with low power. It is something.

〔Example〕

An embodiment of the method of this invention will be described in detail with reference to the drawings.

In the figure, 1 is a laser oscillator, and this laser oscillator is
The oscillated laser beam 2 is guided to a processing head 4 via a plurality of mirrors 3, focused by a lens 5 provided in the processing head 4, and irradiated from a nozzle 6 toward a workpiece 7. 7.

A rear assist gas is supplied to the support nozzle 6 from an assist gas supply device 8, and the workpiece 7 is supplied with the laser beam 2.
It is designed to eject towards.

The assist gas supply device 8 includes a gas cylinder 9 containing, for example, 02 or N2 gas, and a compressor 10. The air processed by the compressor is dehydrated by a dry air unit 11, and then sent to an air tank 12.
Pressure is stored inside.

Then, when the solenoid valves 13.14 are opened, the mixture is mixed with 02 and N2 gas at a predetermined ratio and sent to the pressure regulation circuit 15, and the solenoid valve 1.5 a provided in the pressure regulation circuit 1-5
, 1.5b, i, 5c is opened, and at the same time, its solenoid valve 15a.

A regulator 15d connected in series to 15b and 15c,
The pressure adjusted by 15e and 15f is supplied to the nozzle 6, and the workpiece 7 is cut.

Next, to explain the cutting method using the above laser processing machine, when cutting the workpiece 7 along the arrow in Fig. 3, first pierce the workpiece 7 at the center a, then start cutting, and Already change the cutting direction 9o° to the right at the corner, then change the cutting direction sequentially to 90° to the right at corner C @ 90° to the right at corner d, and finally at corner f
The seventh cutting of the workpiece is completed by changing the direction 90 degrees to the right and proceeding with the cutting.However, in the above cutting, the point where the cutting speed transitions from an unsteady state to a steady state is between the cutting start point a and each corner. Cutting defects occur at six rising points of parts (a) to (f) due to bubbling.

In order to prevent this, the present invention increases the cutting speed in stages as shown in FIGS. ), the NC device 16 sends a speed command signal to the processing head 5 and the workpiece feeding means to control them once.

After cutting for 14 hours at a cutting speed of 10%, the cutting speed was increased to 20% of the steady speed and cutting was continued for 12 hours.

After that, the cutting speed was increased step by step to 40% and 60% of the steady speed, and 1 hour after the start of cutting (T t
The cutting speed is controlled so that the steady speed (100%) is reached at +T2 +Ts +Ta).

In addition, the cutting speed is controlled so that the cutting speed is reduced and the direction is changed at the corner part or f, and then the cutting speed is increased stepwise as described above to reach a steady speed, and the cutting time at each speed is T, to T4 are set in advance in the NC device 16 according to the material and thickness of the workpiece 7, and when cutting, just input the thickness and material of the workpiece 7, and the cutting is appropriate for the workpiece 7. The speed is selected and the feed speed of the processing head 5 and workpiece 7 is controlled.

Also, when cutting the workpiece 7, the assist gas ejected from the nozzle 6 toward the workpiece 7 is controlled by opening the solenoid valves 15a to 15c of the pressure regulating circuit 15 depending on the thickness and material of the workpiece 7. Assist gas at a suitable pressure is supplied to the nozzle 6.

〔Effect of the invention〕

As described in detail above, this invention increases the cutting speed in stages to cut the workpiece when the cutting speed transitions from an unsteady state to a steady state. It is possible to prevent blow-up at the rising edge of the corner portion to be changed, thereby eliminating problems such as poor cutting due to blow-up.

In addition, there is no need to cut at a slower cutting speed than in the past, so there is no reduction in work efficiency, and it is possible to cut difficult-to-cut materials such as copper, Ag, and thick plates using a pulsed laser beam. Even when cutting, it is possible to easily cut by selecting the optimum feed rate.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a block diagram of a laser processing machine, FIG. 2 is a circuit diagram thereof, and FIGS. 3 and 4 are diagrams for explaining the operation. 2 is a laser beam, 7 is a workpiece.

Claims (2)

[Claims] (1) In a laser cutting method in which the workpiece 7 is cut using the laser beam 2 and assist gas, cutting is performed at the start of cutting when the cutting speed transitions from an unsteady state to a steady state, or at the rise of a corner when the cutting direction is changed. A laser cutting method characterized by cutting by increasing the speed in stages. (2) Time to increase cutting speed step by step T_1, T_2・
. . . is set according to the material of the workpiece, the thickness of the plate, etc.