JPH01148484A - Power control method for laser beam - Google Patents

Abstract

PURPOSE:To enable laser beam machining without lowering a working performance with working speed and laser output corresponding correctly by controlling the laser output by peak power and pulse duty against the speed of a machine. CONSTITUTION:A processor reads a working program and decodes a command, outputting the respective moving instruction to a position control circuit 11. A speed is calculated from the moving command value per unit hour and a pulse duty is calculated according to the speed. In case of this pulse duty being found at >=100% by studying as to whether >=100% or not the pulse duty is fixed at 100%. The peak power corresponding to the speed is calculated in case of <=100%. The peak power and pulse duty are then outputted to an output control circuit 2. Whether the moving command of one block is completed or not is then studied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser power control method, and particularly to a power control method in which output is controlled by peak power and pulse duty.

[Conventional technology]

Laser processing machines have become widely used because they are combined with numerical control devices and can process complex shapes at high speed. In general, there is no problem when machining straight lines or curves with a large radius of curvature, but when machining corners or sharp edges of the workpiece,
If the laser output is not controlled in accordance with the speed, the retention of thermal energy from the laser beam at the edge and the retreating heat will cause melting damage to the edge, resulting in a decrease in accuracy and deterioration of the material.

In order to solve these problems, there is a method called "Japanese Patent Application No. 107824/1983" that controls the laser output by changing the pulse duty depending on the speed. This method controls the laser output.

In addition to this, a method of controlling the laser output by controlling the peak power is also known.

[Problem that the invention seeks to solve]

However, in the method of controlling the laser output using only the pulse duty, when the speed exceeds a certain value, the pulse duty exceeds 100%, which is uncontrollable, and it becomes impossible to control the laser output corresponding to the speed.

On the other hand, with the method of controlling laser output using only peak power, it is known that the higher the peak power, the better the machining characteristics when processing a workpiece with laser machining, and when the speed decreases, the machining performance deteriorates. There is a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a power control method that controls laser output using both peak power and pulse duty parameters.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a first invention that controls the laser output according to an NC command, and controls the laser output as a function of the movement command speed of the machine or the actual speed of the machine. In the power control method, the laser output is controlled by pulse duty according to the feed speed of the machine or the actual speed of the machine, and when the pulse duty exceeds 100%, the pulse duty is set to 100%.
Provided is a laser power control method characterized by controlling the laser output at a peak power while fixing the peak power to a peak power.

Further, in a second invention, in a laser power control method, the laser output is controlled by an NC command, and the laser output is controlled as a function of a movement command speed of the machine, or an actual speed of the machine, comprising: a feed rate of the machine, or When the actual speed of the machine is higher than the program command speed using the feed speed override function, etc., the laser output is controlled at peak power, and when the feed speed or the actual speed is less than the program command speed, the laser output is controlled at pulse duty. A method for controlling laser power is provided, the method comprising controlling the output power of a laser.

[Effect]

The pulse duty is calculated from the commanded speed or actual moving speed of the machine, and when this becomes 100% or more, the peak power is controlled as a function of the commanded speed or actual moving speed. Conversely, when the pulse duty is less than 100%,
Control the laser output with the calculated pulse duty.

Further, the program command speed and the actual command speed are compared, and if the actual command speed is larger than the program command, the peak power is controlled as a function of the actual command speed.

Conversely, when the moving speed is smaller than the command speed, the pulse duty is controlled as a function of the moving speed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a configuration diagram of a laser processing machine used in an embodiment of the present invention. 1 is a processor that controls the whole, and 2 is an output control circuit that converts an output command value into a current command value and outputs it, and has a built-in DA converter that converts a digital value into an analog output. Reference numeral 3 denotes a laser power source, which rectifies a commercial power source and outputs a high-frequency voltage according to a command from the output control circuit 2. 4 is a discharge tube;
Laser gas is circulated inside and a high frequency voltage from the laser power source 3 is applied to excite the laser gas. 5
is a total reflection mirror that reflects the laser beam, and 6 is an output mirror. By reciprocating between the total reflection mirror 5 and the output mirror 6, the laser beam receives energy from the excited laser gas.
It is amplified and a portion is output from the output mirror 6 to the outside. The output laser beam 9 changes direction with a pendamor mirror 7,
The condensing lens 8 irradiates the surface of the workpiece.

Reference numeral 10 denotes a memory in which the program, parameters, etc. are stored, and a non-volatile bubble memory or the like is used. 11 is a position control circuit, the output of which is amplified by a servo amplifier 12, controls the rotation of a servo motor 13, controls the movement of a table 16 by a ball screw 14 and a nut 15, and processes a workpiece 17; Although the position control circuit 11 is shown for only one axis, in reality, position control circuits for two axes are required. 18 is a display device, and a CRT, liquid crystal device, or the like is used.

Here, the processor 1 reads out the machining program stored in the memory 10, decodes the command, outputs the amount of movement of each axis to the position control circuit 11, and at the same time calculates the movement speed from this amount of movement per unit time. Calculate.

Here, there are the following two methods of controlling the laser output.

(1) Calculate the pulse duty from the moving speed data, and when the pulse duty is 100% or less, keep the peak power constant and output the pulse duty as a command value, and when the pulse duty is 100% or more, The pulse duty is set to 100% and the peak power is controlled.

(2) Compare the moving speed data and the commanded speed. If the moving speed is greater than the commanded speed, the pulse duty is kept constant and the peak power is controlled. If the moving speed is smaller than the commanded speed, the peak power is kept constant and the pulse duty is controlled. Control.

Next, the laser power source 3 receives the analog voltage from the output control circuit 2, applies a voltage to the discharge tube 4, and controls the current flowing through the discharge tube 4.

The discharge tube 4 has a total reflection mirror 5 and an output mirror 6 at both ends, forming a Fapry-Perot resonator, which amplifies the laser generated by the discharge and outputs it to the outside. The laser beam 9 output from the laser oscillator is transmitted by the pendamor mirror 7,
The direction is changed, the light is made into a small spot by the condensing lens 8, and the workpiece 17 is irradiated with the light.

Next, the operation of the first embodiment is explained according to the time chart.
explain. FIGS. 2(a), (b), and (C) show time charts of the first embodiment.

FIG. 2(a) shows the relationship between time and machine speed, where the horizontal axis is time (1) and the vertical axis is speed. FIG. 2(b) shows the relationship between time and peak power, where the horizontal axis is time (1) and the vertical axis is peak power. Figure 2 (c) shows the relationship between time and pulse duty, where the horizontal axis is time (1) and the vertical axis is pulse duty (%). .

As shown in FIG. 2(a), the speed of the machine decreases from a constant speed at time Ta, reaches a constant speed at time Tb, and then at time T
It accelerates at time c and reaches a constant speed at time Te.

As shown in FIG. 2(b), the peak power is constant until time Td, and the laser output is controlled by pulse duty until time Td.

As shown in Fig. 2 (C), the laser output is controlled by pulse duty according to the speed of the machine until time Td, and after time Td, the pulse duty is fixed at 100% and the laser output is controlled by the peak power. Output is controlled.

Next, a second embodiment will be described based on a time chart. FIGS. 4(a), (b), and (e) show time charts of the second embodiment. FIG. 4(a) shows the relationship between time and machine speed, where the horizontal axis is time (1) and the vertical axis is speed. Figure 4(b) shows the relationship between time and peak power,
The horizontal axis is time (1) and the vertical axis is peak power. Figure 4 (
C) represents the relationship between time and pulse duty, where the horizontal axis is time (1) and the vertical axis is pulse duty (%). In each figure, the time axes are on the same scale and match.

As shown in FIG. 4(a), the speed of the machine decreases from a constant speed at time Ta, reaches a constant speed at time Tb, and then decreases to a constant speed at time T.
It accelerates at time c and reaches a constant speed at time Te.

As shown in FIG. 4(b), the peak power is constant until time Td, and the laser output is controlled by pulse duty until time Td.

As shown in FIG. 4(C), the laser output is controlled by pulse duty according to the speed of the machine until time Td, and after time Td, the pulse duty is fixed at the command value and the laser output is controlled by the peak power. Output is controlled.

Next, the software processing of the first embodiment will be described. FIG. 3 shows a flowchart of the software of this embodiment. In the figure, the number following S indicates the step number.

[S1], [S2] The processor 1 reads the computer program and decodes the instructions.

[S3] Each movement command is output to the position control circuit 11.

[S4] Calculate the speed from the movement command value per unit time.

[S5] Calculate the pulse duty according to the speed.

[S6] Check whether the pulse duty is 100% or more. 1
If it is 00% or more, go to S7, and if it is less than 00%, go to S9.

[S7] The calculated pulse duty must be 100% or more, so first, the pulse duty is fixed at 100%.

[S8] Calculate peak power according to speed.

[S9] Output the peak power and pulse duty to the output control circuit.

(SIO) Check whether the movement command for one block has been completed. If the process has ended, go to Sl; if not, go to S3.

Next, the software processing of the second embodiment will be described. FIG. 5 shows a flowchart of the software of this embodiment. In the figure, the number following S indicates the step number.

[S1], [S2] The processor 1 reads the computer program and decodes the instructions.

[S3] Each movement command is output to the position control circuit 11.

[S4] Calculate the speed from the movement command value per unit time.

[S5] Check whether the moving speed is greater than or equal to the commanded speed. If the command speed is higher than the command speed, the flow goes to S6, and if it is lower than the command speed, the flow goes to S7.

[S6] Calculate the peak power according to the speed while keeping the pulse duty at the command value.

[S7] Calculate the pulse duty according to the speed while keeping the peak power at the command value.

[S8] Output the peak power and pulse duty to the output control circuit.

(S9) Check whether the movement command for one block has been completed.

If the process has ended, go to Sl; if not, go to S3.

In this way, the laser output is controlled by controlling the peak power and pulse duty according to the speed of the machine.

As a result, the speed of the machine and the laser output correspond accurately, and the precision of laser processing can be increased.

〔Effect of the invention〕

As explained above, in the present invention, with respect to the speed of the machine,
Since the laser output is controlled by peak power and pulse duty, the processing speed and laser output correspond accurately, and processing can be performed at low speeds without reducing the peak power, so there is no reduction in processing performance. Laser processing can be performed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a laser processing machine used in an embodiment of the present invention. FIGS. 2(a), (b), and (C) are time charts of the first embodiment of the present invention. The figure shows a flowchart diagram of the software of the first embodiment of the present invention. 4(a), (b), and (c) are time charts of the second embodiment of the present invention, and FIG. 5 is a software flowchart of the second embodiment of the present invention. 1--------------------Processor 2--
1--・--------1 output control wholesale circuit 3--
−−−−1−−−−−−Laser power supply 4・・−・−・
−・−・Discharge tube 9・−−−−−−−・−・−・Laser beam 10−−
−−−−−−−−−−−−−Memory 11−−−−−・
−・−・・−Position control circuit 16−−−−−−−・−・−
Table 17 - Work patent applicant Fanuc Corporation Figure 2 Figure 4

Claims (2)

[Claims] (1) In a laser power control method in which the laser output is controlled by an NC command and the laser output is controlled as a function of the movement command speed of the machine or the actual speed of the machine, A laser power control method comprising: controlling the laser output with a pulse duty according to the pulse duty, fixing the pulse duty at 100% when the pulse duty exceeds 100%, and controlling the laser output with a peak power. (2) In a laser power control method in which the laser output is controlled by an NC command and the laser output is controlled as a function of the movement command speed of the machine or the actual speed of the machine, the feed rate of the machine or the actual speed of the machine is , by using the feed speed override function, etc., the laser output is controlled by peak power when the speed is higher than the program command speed, and the laser output is controlled by pulse duty when the feed speed or the actual speed is lower than the program command speed. A laser power control method characterized by: