JPH07185848A - Laser beam machining control device - Google Patents

Abstract

PURPOSE:To realize the laser beam machining with excellent precision of the machined shape without sacrificing the machining speed by preventing generation of melt-down due to the excessive energy at a corner part or the like. CONSTITUTION:A function table storage 31 having a plurality of function tables of the laser beam output command value with the function of the machining speed command value as the accelerating function table 31a and the decelerating function table 31b is prepared, and selection of either of the accelerating function table 31a or the decelerating function table 31b is made by a laser beam output command selecting part 29 according to the acceleration detected by acceleration detecting means 21, 23. The laser beam output command value by the machining speed command value according to the relative moving speed to be detected by speed detecting means 17, 19 is read out of the selected function tables 31a, or 31b, and outputted to a laser beam oscillator 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing control device, and more particularly to a laser processing control device for variably controlling a laser output according to a processing state.

[0002]

2. Description of the Related Art In a laser machining apparatus whose operation is controlled by a numerical control device, a laser output and a preset laser output are set on a plane orthogonal to an emission optical axis of a laser according to an NC program code interpreted by the numerical control device. When performing laser processing such as cutting a predetermined shape by performing position control under speed, in order to improve the processing shape accuracy, CW
The pulse oscillation mode is used rather than the (continuous) oscillation mode. This is because, in the pulse oscillation mode, the average heat input to the workpiece is smaller than that in the CW oscillation mode, so the machining speed is inevitably slowed, and the tracking delay of the servomotor of the feed system is reduced accordingly. This is because the processed shape accuracy is improved.

The position control is generally performed by a closed loop control method and includes a delay time. Therefore, in precision machining, in order to reduce a machining error caused by the delay time, a machining direction such as a corner portion or a minute arc portion is reduced. The machining speed may be changed during the machining of the portion where a sharp change occurs. Further, the change of the machining speed may be performed due to the limitation due to the calculation speed of the numerical control device, the tracking delay of the servo motor, or the like.

Further, the laser output is changed by an NC program in response to the change in the processing speed.

[0005]

When a complex shape is machined or high machined shape accuracy is required, the laser output control in response to the machining speed may be performed in the pulse oscillation mode.
However, in this case, the processing speed is sacrificed, and the processing speed control with a high degree of freedom cannot be performed.

As a natural result, in order to obtain a high processed shape accuracy, the processing speed becomes slower, which improves the processed surface accuracy. On the contrary, when the processed shape accuracy may be poor, The speed can be set faster, but the precision of the machined surface becomes worse. Due to this correlation, it is considered difficult to perform machining with high machining accuracy and high machining speed.

The deterioration of the machining shape accuracy due to the response delay of the servo system can be dealt with on the NC program, but the burn-through due to excess energy can be dealt with only by controlling the laser output.

FIG. 4 shows that when the laser output is not controlled in accordance with the processing speed, a processing region in which the laser output becomes excessive is generated in the relationship between the processing speed and the laser output, and FIG. 5 shows the delay time. 2 shows an example of generation of a machining delay portion due to a positioning delay due to the above and a burn-through portion due to excess energy. From these figures, it can be understood that the shape accuracy is deteriorated due to the burn-through especially at the corners.

The present invention has been made by paying attention to the above-mentioned problems, and directly detects the actual machining speed to suppress the influence of the tracking delay of the servo system, and the laser intensity depending on the actual machining speed. By controlling the (laser output) and giving a controlled variable to the machined part at a rate according to the magnitude of the specific heat of the workpiece, it is possible to prevent burn-through due to excess energy at the corners, etc. An object of the present invention is to provide a laser processing control device that enables laser processing with good shape accuracy to be performed without sacrificing a large processing speed.

[0010]

According to the present invention, the speed detecting means for detecting the relative movement speed between the optical axis of the laser beam emitted from the laser oscillator to the workpiece and the workpiece is provided. An acceleration detecting means for detecting the acceleration of relative movement between the optical axis of the laser and the workpiece, and a function table of the laser output command value with the processing speed command value as a function. Function table storage having a plurality of tables, and laser output command selecting means for selectively setting which of the acceleration function table and the deceleration function table to be used according to the acceleration detected by the acceleration detecting means. And a laser output command value based on the processing speed command value corresponding to the relative movement speed detected by the speed detection means is selected by the laser output command selection means. It is intended to be achieved by the laser machining control apparatus characterized by reading from tables and a laser output instruction value determining means for determining the laser output command value to be output to the laser oscillator.

The laser processing controller according to the present invention is
A laser that calculates laser output command values for a function table for acceleration and a function table for deceleration using a machining speed command value as a function in a numerical control device that controls the operation of the laser processing device according to the condition of the workpiece. Output command value calculation means may be provided, and the function table storage may be given a laser output command value by the laser output command value calculation means (input is possible from the outside).

Further, in the laser processing control apparatus according to the present invention, the acceleration detecting means is composed of an acceleration sensor for directly detecting the acceleration of relative movement between the laser emission optical axis and the workpiece.

[0013]

According to the above-described structure, the function table for acceleration and the function table for deceleration are prepared as the function table of the laser output command value using the machining speed command value as a function, and the laser beam is output by the speed detecting means. The relative movement speed between the optical axis and the work piece, that is, the actual processing speed is detected, and the acceleration of the relative movement between the laser emission optical axis and the work piece, that is, the speed change amount is detected by the acceleration detecting means, and the acceleration is detected. The laser output command selecting means selectively uses the function table for acceleration and the function table for deceleration according to the acceleration detected by the means, and the laser output according to the machining speed command value according to the relative moving speed detected by the speed detecting means. The command value is read from the selected function table for acceleration or deceleration and is commanded to the laser oscillator.

As a result, the laser output control corresponding to the actual machining speed is performed in consideration of the amount of change in the actual machining speed.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a laser processing controller according to the present invention. The laser processing apparatus 1 is a laser processing apparatus of a fixed optical axis, which is configured to move the workpiece W along the X axis along a laser oscillator 3 and an orthogonal table surface perpendicular to the optical axis L of the laser emitted from the laser oscillator 3. It has an X-axis servomotor 5 and a Y-axis servomotor 7 which positionally drive in each of the direction and the Y-axis direction.

The laser oscillator 3 receives a laser output command from the numerical controller 9 and the laser output controller 1
A laser output command value is given from 1, and laser output is performed according to the laser output command value.

The numerical controller 9 interprets the NC program, issues an X-axis feed command to the axis feed drive unit 13 which is a driver of the X-axis servo motor 5, and an axis feed drive unit 15 which is a driver of the Y-axis servo motor 7. The Y-axis feed command is output to each.

On the orthogonal table surface portion of the laser processing apparatus 1, the relative movement speed (actual processing speed) between the optical axis L of the laser irradiated onto the workpiece W from the laser oscillator 3 and the workpiece W.
As means for detecting V, an X-axis speed sensor 17 that directly detects the moving speed Vx of the workpiece W in the X-axis direction and a Y-axis speed sensor that directly detects the moving speed Vy of the workpiece W in the Y-axis direction. And 19 are provided.

On the orthogonal table surface portion of the laser processing apparatus 1, as means for detecting the relative movement acceleration A between the optical axis L of the laser and the workpiece W, the acceleration of the movement of the workpiece W in the X-axis direction is detected. X-axis acceleration sensor 21 that directly detects Ax
And a Y-axis acceleration sensor 23 that directly detects the acceleration Ay of the movement of the workpiece W in the Y-axis direction.

The acceleration A may be obtained by a differential operation of the relative moving speed V, but in order to obtain high responsiveness, an acceleration sensor such as a size sensor system that directly detects the acceleration in each axial direction is used. Preferably.

The laser output control device 11 includes a vector operation circuit 25, a laser output command value determination unit 27, a laser output command selection unit 29, and a function table storage 31.

The function table storage 31 has two function tables of the laser output command value using the machining speed command value Vχ as a function table 31a for acceleration and a function table 31b for deceleration. 31a
Defines the laser output command value Pχ, and the deceleration function table 31b defines the laser output command value P'χ.

The vector calculation circuit 25 has a relative moving speed calculation section 33 and an acceleration calculation section 35.

The relative movement speed calculation unit 33 inputs a signal indicating the movement speed Vx of the workpiece W in the X-axis direction from the X-axis speed sensor 17, and the Y-axis direction of the workpiece W from the Y-axis speed sensor 19. The signal indicating the moving speed Vy is input, and vector calculation is performed by the following calculation formula to calculate the relative moving speed V between the optical axis L of the laser and the workpiece W.

[0026]

## EQU1 ## V = √ (Vx ² + Vy ² ) The acceleration calculation unit 35 inputs a signal indicating the acceleration Ax of the workpiece W in the X-axis direction from the X-axis acceleration sensor 21 and outputs the signal from the Y-axis acceleration sensor 23. A signal indicating the acceleration Ay of the workpiece W in the Y-axis direction is input, and vector acceleration is executed by the following arithmetic expression to calculate the acceleration A of the workpiece.

[0027]

## EQU2 ## A = √ (Ax ² + Ay ² ) The signal (voltage signal) of the relative movement speed V output from the relative movement speed calculation unit 33 is input in parallel to the two comparators 37 and 39 of the laser output command value determination unit 27. To be done.

The laser output command value determining unit 27 performs discrimination and follow-up control for determining the laser output command value in response to the relative moving speed V.
7 and 39 are given a hysteresis potential corresponding to a predetermined step, for example, two steps of the function table of the function table storage 31 from the hysteresis voltage applying section 41, and the digital output of the up / down counter 43 is analogized by the D / A converter 45. The feedback voltage obtained by the conversion is applied to the reference voltage side, and when the relative movement speed V increases beyond the hysteresis width, the EX-OR gate 47 commands the up-down counter 43 to up-count, and the reference of the comparator 37. When the voltage becomes higher than the signal voltage of the relative movement speed V, the up count command is stopped. On the other hand, when the relative movement speed V has decreased to the hysteresis width or more, the EX-OR gate 49 instructs the up-down counter 43 to down-count, and the reference voltage of the comparator 39 becomes higher than the signal voltage of the relative movement speed V. For example, stop the down count command. The hysteresis width can be arbitrarily changed from the outside by using a variable resistor.

The up / down counter 43 is given a clock pulse by the clock pulse generator 51, and at the time of up-counting, the laser output command value is stepped by the number of clock pulses from the desired value V0 (P1) of the function table by the up-step signal. On the other hand, when the count is down, the laser output command value is stepped down by the number of clock pulses from the desired value V0 (P1) in the function table by the down step signal.

As a result, the speed signal (step) Vχ, which is the read key for the laser output command values Pχ and P'χ read from the function table 31a or 31b of the function table storage 31, is determined, and the laser output command of the corresponding speed signal Vχ is determined. The value Pχ or P′χ is output to the laser oscillator 3.

The signal of the acceleration A output from the acceleration calculator 35 is given positive and negative polarities by the polarity signal adder 53 and is input to the non-inverting amplifier 55 of the laser output command selector 29.

The acceleration calculation section 35 includes a selection switch section 57 for inputting an amplified signal from the non-inverting amplifier 55.
The selection switch unit 57 receives a predetermined hysteresis voltage from the hysteresis voltage applying unit 59, and if the acceleration A is not zero, selects the acceleration function table 31a, and the acceleration A is on the negative side (deceleration or more) than the hysteresis width. If the value exceeds a predetermined value in), the function table 31b for deceleration is selected. This hysteresis width is set for the purpose of ignoring the uneven feed rate in the mechanical system.

The laser output command values Pχ and Pχ ′ for the function table for acceleration and the function table for deceleration using the machining speed command value Vχ as a function are laser output command value calculators included in the numerical controller 9. 61 is transferred.

The laser output command value calculation unit 61, every time the processing conditions such as the material of the workpiece W and the plate thickness are newly input,
Prior to the start of laser processing, the laser output command value P for the acceleration function table using the processing speed command value Vχ as a function.
χ is calculated by a function arithmetic expression P = f (Vχ) using a coefficient f, and the laser output command value P for the function table for deceleration is calculated.
′ Χ is calculated by the functional operation formula P ′ = f ′ (Vχ) using the coefficient f ′.

The range of the function Vχ in this case is, as illustrated in FIG. 2, a range between V0 where the laser output is zero (minimum) and Vn where the laser output is maximum.

The coefficients f and f'are determined according to the acceleration, the material of the workpiece W, the plate thickness, etc., and their proper values are obtained in advance by experiments or the like, and the laser output command value calculation unit 6 is used.
1 is stored together with the above-mentioned function calculation formula.

In the piercing process, the laser output control device 11 inputs a command laser output command from the numerical control device 9, and the accelerations Ax and Y detected by the X-axis acceleration sensor 21.
The acceleration A based on the acceleration Ay detected by the axial acceleration sensor 23, the relative movement speed Vx detected by the X-axis speed sensor 17, and the relative movement speed V detected by the Y-axis speed sensor 19.
The relative movement speed V based on y is monitored, and if the acceleration A and the relative movement speed V are both zero, the laser output command value for piercing is output to the laser oscillator 3 as instructed. As a result, the oscillator 3 outputs a laser having an intensity suitable for piercing.

At the time of processing, the laser output control device 11
Initially, a prescribed laser output command is issued as in the case of piercing processing, but when the above-mentioned acceleration A becomes non-zero, the function table 31a for acceleration is selected and the processing speed command according to the above-mentioned relative moving speed V is selected. The laser output command value Pχ of the value Vχ is used as the acceleration function table 31a of the function table storage 29.
It is read out and output to the laser oscillator 3. As a result, the laser oscillator 3 outputs a laser beam having an intensity corresponding to the laser output command value Pχ.

When there is a speed decrease in a minute arc portion, but the acceleration A is small and is within the hysteresis range of the acceleration, the function table 31a for acceleration is kept selected, but the acceleration A has a hysteresis width. When the negative side (deceleration) exceeds the predetermined value, the function table to be used is switched to the deceleration function table 31b.

As a result, at this time, the laser output command value P'χ determined by the deceleration function table 31b is output to the laser oscillator 3, and the laser oscillator 3 has a strength corresponding to the laser output command value P'χ. Laser output.

FIG. 3 shows the relationship between the relative moving speed V and the acceleration A and the laser output in the laser output control as described above in time series.

In the above, the present invention has been described in detail with respect to a specific embodiment, but the present invention is not limited to this, and various embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

[0043]

As can be understood from the above description, according to the laser processing control apparatus of the present invention, the function table for acceleration and the function table for deceleration are used as the function table of the laser output command value in which the processing speed command value is a function. A function table is prepared, and the laser output command selecting means selectively uses the function table for acceleration and the function table for deceleration in accordance with the acceleration detected by the acceleration detecting means to obtain the relative movement speed detected by the speed detecting means. The laser output command value according to the corresponding machining speed command value is read from the selected function table for acceleration or deceleration and output to the laser oscillator. Laser output control is performed according to the actual processing speed, and laser processing with high processing accuracy is performed without sacrificing processing speed significantly. Is Fame.

The acceleration is detected by using the acceleration sensor,
Since acceleration / deceleration and constant-speed machining are discriminated, it is possible to suppress the detection delay when the hysteresis width on the speed signal side is widened within the detection error of the acceleration sensor. Since the detection delay time is determined by the detection sensitivity and the detection step width because it is taken in from the sensor provided in the section, it is not affected by the delay of the mechanical system or the delay of the servo control.

Since the function table is calculated by the information in the numerical control device, the delay time is only read from the function table, and since the function table is created in the numerical control device, the data can be changed freely. Therefore, it is possible to control the speed and output with a high degree of freedom.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a laser processing control device according to the present invention.

FIG. 2 is a graph showing the relationship between relative moving speed and laser output.

FIG. 3 is a time-series graph showing the relationship between relative output speed and acceleration and laser output in the laser processing control apparatus according to the present invention.

FIG. 4 is a graph showing that a processing area in which a laser output becomes excessive occurs in a relationship between a processing speed and a laser output.

FIG. 5 is an explanatory diagram showing an example of generation of a machining delay portion due to a positioning delay due to a delay time and a burn-through portion due to excess energy.

[Explanation of symbols]

 1 Laser Processing Device 3 Laser Oscillator 5 X-axis Servo Motor 7 Y-axis Servo Motor 9 Numerical Control Device 11 Laser Output Control Device 17 X-axis Speed Sensor 19 Y-axis Speed Sensor 21 X-axis Acceleration Sensor 23 Y-axis Acceleration Sensor 25 Vector Calculation Circuit 27 Laser Output Command Value Determining Section 29 Laser Output Command Selecting Section 31 Function Table Storage 31a Function Table for Acceleration 31b Function Table for Deceleration 33 Relative Movement Speed Calculator 35 Acceleration Calculator 37, 39 Comparator 43 Up / Down Counter 51 Clock Pulse Generator 57 Selection switch section 61 Laser output command value calculation section

Claims (3)

[Claims] 1. A speed detecting means for detecting a relative moving speed of a laser and an optical axis of a laser irradiated onto a workpiece by a laser oscillator, and an acceleration of relative movement between the optical axis of the laser and the workpiece. A function table storage having a plurality of function tables of a laser output command value as a function of the machining speed command value as a function table for acceleration and a function table for deceleration, and the acceleration detection means. A laser output command selecting means for selectively setting which of the acceleration function table and the deceleration function table is used according to the acceleration, and the relative movement speed detected by the speed detecting means. The laser output command value based on the processing speed command value is read out from the function table selected by the laser output command selection means, and is read by the laser oscillator. The laser machining control apparatus characterized by and a laser output instruction value determining means for determining obtain laser output command value. 2. A laser output command value for a function table for acceleration and a function table for deceleration, which uses a processing speed command value as a function, is set as a condition of a workpiece in a numerical controller for controlling the operation of the laser processing device. 2. The laser processing apparatus laser according to claim 1, further comprising: laser output command value calculation means for calculating according to the function table storage, wherein the function table storage is given a laser output command value by the laser output command value calculation means. Output control device. 3. The laser processing according to claim 1, wherein the acceleration detecting means is composed of an acceleration sensor that directly detects the acceleration of relative movement between the optical axis of the laser and the workpiece. Control device.