JPH0347686A - Duty control method for oscillation pulse of laser beam oscillator - Google Patents

Abstract

PURPOSE:To improve machining efficiency at the time of changing the duty ratio of an oscillation pulse of a laser beam oscillator by increasing change rate in the region of the high duty ratio and decreasing in the region of the low duty ratio. CONSTITUTION:At the time of decreasing gradually the oscillation pulse from a high value to a low value, a present value of the duty ratio is decreased at the maximum change rate (a), at the intermediate change rate (b) and at the minimum change rate (c) in the region from 100 to D1%, in the region from D1 to D2% and in the region lower than D2%, respectively. By this method, the duty regions are determined by the preset duty values D1 and D2 and the duty ratio can be changed at the maximum speed where an arc is not discharged at each region and machining efficiency is improved to that extent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a control technique for a laser oscillator, and particularly to a duty control method for changing the duty ratio of an oscillation pulse.

(Prior Art) In a numerically controlled laser processing machine, a processing method is known in which the duty ratio of the oscillation pulse of a laser oscillator is changed depending on the part to be processed in a series of processing steps.

In the conventional device, as shown in FIG. 4, when the duty ratio of the oscillation pulse is gradually decreased from a large value d1 to a small value d2, a control method is adopted in which the duty ratio is decreased at a constant rate of change.

(Problems to be Solved by the Invention) The faster the duty ratio is changed during processing, the shorter the processing cycle can be. For this purpose, it is better to increase the rate of change when gradually reducing the duty ratio from dl to d2. However, if the rate of decrease in the duty ratio is too large (then the area where the duty ratio is small (20 to 10%)
There is a problem in that the oscillator is more likely to cause arc discharge in the range of Area with large duty ratio (
(100 to 50%), there is no problem with arc discharge even if the reduction rate is made sufficiently large, but since the control method uses a constant reduction rate, the reduction rate must be set small according to the region where the duty ratio is small. Therefore, it takes time to change the duty ratio.

This invention was made in view of the conventional problems mentioned above, and its purpose is to provide a duty control method that allows changing the duty ratio, particularly changing the duty ratio from a large value to a small value, at a higher speed. Our goal is to provide the following.

[Structure of the Invention] (Means for Solving the Problems) In this invention, when changing the duty ratio, a control method is provided in which the reduction rate of the duty ratio is increased in a region where the duty ratio is large and decreased in a region where the duty ratio is small. And so.

(Function) In this invention, the reduction rate is made sufficiently large in the region where the duty ratio is large so that there is no risk of shifting to arc discharge even if the duty change rate is too large, and in the IN region where the duty ratio is small where there is a risk of arc discharge. Then, reduce the rate of decrease.

(Embodiment) FIG. 3 shows a schematic configuration of a drive/control system for a laser oscillator to which the present invention is applied. As is well known, a pulse signal with a predetermined frequency and duty ratio is generated by the controller 2 of the power supply unit 1, and this pulse signal controls the switching of the high-voltage power supply of the driver 3, and the high-voltage output of the driver 3 controls the oscillator 4. Driven. controller 2
is a control circuit using a microcomputer, and can generate pulse signals of arbitrary frequency and duty ratio using a digital control method.

FIG. 2 shows control characteristics according to an embodiment of the present invention, and the first
The figure shows a control procedure that embodies this control characteristic.

As shown in Figures 1 and 2, when the duty ratio of the generated pulse is gradually decreased from a large value to a small value, ■The largest change occurs in the area where the current value of the duty ratio is from 100% to 01%. The current value of the duty ratio falls from D+% to D2%, and the intermediate rate of change has already decreased (Steps 101, 103, 104). ), (■When the current value of the duty ratio is smaller than D2%, it is decreased at a very small rate of change C (step 105).

As described above, in this example, the duty region is determined by the duty values D+ and D2 set in advance as parameters, and the duty ratio can be changed in each region by the maximum speed that does not cause arc discharge, and the machining efficiency is improved accordingly. do.

In the above embodiment, the rate of change is switched in three stages.
It may be possible to switch in more steps.

The present invention is not limited to the above-described embodiments, but can be implemented in any appropriate manner by making appropriate design changes.

[Effects of the Invention] As explained in detail above, according to the present invention, the reduction rate is reduced in the region where the duty ratio is small to prevent arc discharge, while the reduction rate is increased in the region where the duty ratio is large. Therefore, the time required to change the duty ratio can be reduced compared to the conventional method.

[Brief explanation of drawings]

FIG. 1 is a flowchart of a duty control method according to an embodiment of the present invention, and FIG. 2 is a control characteristic diagram according to the same embodiment.
FIG. 3 is a schematic diagram of a drive/control system for a laser oscillator to which the present invention is applied, and FIG. 4 is a control characteristic diagram of a conventional method. a, b, c...Decrease rate D...Duty ratio

Claims (1)

[Claims] In a method for controlling the duty of the oscillation pulse of a laser oscillator that outputs pulsed laser to a laser processing machine, when changing the duty ratio of the oscillation pulse of the laser oscillator, the rate of change of the duty ratio is set to be large in the region where the duty ratio is large; A method for controlling the duty of an oscillation pulse of a laser oscillator, characterized by reducing the duty in a region where the ratio is small.