JPH056211A - Gap control method for laser beam machine - Google Patents

Abstract

PURPOSE:To prevent a nozzle from interferring a work even when gap control is executed to the work where a missed part exists. CONSTITUTION:When a nozzle 5 is positioned in a prescribed distance suitable for executing laser beam the surface of a work 7, a coordinate value Zoc of the Z axis of the nozzle is detected in advance and based on this detected Z axis coordinate value of the nozzle, a clamp coordinate value ZCL is decided for limiting the movement of the nozzle in the direction of the work. Next, when moving the nozzle relatively to the work in an X-Y direction, the Z axis movement of the nozzle is controlled so that the Z axis coordinate value of the nozzle can not be smaller than the clamp coordinate value ZCL decided in advance. Namely, at a work missing part 71, the nozzle is prevented from being lowered rather than the surface of the work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gap control method for a laser beam machine for machining a work while controlling the gap between the nozzle and the work to a constant value based on a detection signal from a gap detector provided in the nozzle. In particular, the present invention relates to a gap control method for a laser processing machine that prevents a nozzle from interfering with a work even if a work having a missing portion is gap-controlled.

[0002]

2. Description of the Related Art Conventionally, a laser beam machine collects a laser beam by a condenser lens or the like and irradiates it on one point of a work, and heats the irradiated part for processing. Piercing and cutting are performed by evaporating the irradiated part by narrowing it down to a very small spot, and the spot diameter is expanded by slightly shifting the focus to weld the work piece in a molten state.

Therefore, it is required that the spot diameter of the laser beam applied to the work be constant at all times, but in actual machining, the spot diameter on the work may often change due to warping of the work. In order to prevent this, the gap control is performed to keep the distance between the nozzle and the work constant while executing the machining program.

Normally, in the gap control, a gap detector is provided in the nozzle so that the distance between the nozzle and the work (gap).
Is detected, and the deviation is obtained by comparing the detected value with a reference value. The nozzle position is controlled so that this deviation becomes zero, and the distance between the nozzle and the work is kept constant. As the gap detector, beginning with a capacitance type distance detector that detects the capacitance between the nozzle and the work to detect the distance between them, reflected light amount type, eddy current type,
Non-contact type distance detectors such as magnetic type are often used.

[0005]

However, when a work has a missing portion due to cutting work, or when there is a work-free portion in a region to be processed, laser processing attempts to shift to such a work-missing region. Then, the gap detector loses the work to be detected, and detects the position of a work other than the work far away from the detector. For this reason, the value of the deviation becomes large, and the nozzle is greatly moved in the work direction in order to reduce the deviation, and as a result, the nozzle lowers below the work surface and interferes with the end of the work. There was a point.

The present invention has been made in view of the above circumstances, and a gap control method for a laser processing machine in which the nozzle does not interfere with the work even if the gap control is performed on the work having a missing portion. The purpose is to provide.

[0007]

In order to solve the above problems, the present invention controls the gap between the nozzle and the work to a constant value based on a detection signal of a gap detector provided in the nozzle. In the gap control method of a laser processing machine for processing the work, when the nozzle is at a position of a predetermined distance suitable for performing the laser processing from the surface of the work, the coordinate value of the Z axis of the nozzle is detected. ,
Based on the detected Z-axis coordinate value of the nozzle, a clamp coordinate value for limiting the movement of the nozzle in the work direction is determined, and the nozzle moves in the XY directions relative to the work. At this time, there is provided a gap control method for a laser beam machine, wherein movement of the nozzle in the Z-axis direction is controlled so that the Z-axis coordinate value of the nozzle does not become smaller than the determined clamp coordinate value. To be done.

[0008]

When the nozzle is located at a predetermined distance suitable for laser processing from the surface of the workpiece, the Z
The coordinate value of the axis is detected, and the clamp coordinate value for limiting the movement of the nozzle in the work direction is determined based on the detected Z-axis coordinate value of the nozzle.

Next, the nozzle is moved relative to the workpiece by X.
When moving in the Y direction, the movement of the nozzle in the Z-axis direction is controlled so that the Z-axis coordinate value of the nozzle does not become smaller than the clamp coordinate value determined previously. That is, the movement of the nozzle in the work direction is restricted by the clamp coordinate value, and the nozzle is prevented from interfering with the work surface.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram of the hardware of the laser processing machine for carrying out the present invention. In the figure, the processor 11 reads out a system program stored in the ROM 12a via the bus 10 and controls the overall operation of the control device 1 according to the system program. RAM12b is DRA
M, which stores temporary calculation data. The non-volatile memory 12c is backed up by a battery (not shown) and stores a machining program and various parameters.

The processor 11 issues a laser output command to the laser oscillator 2 via the interface 13, and the laser oscillator 2 outputs the laser beam 3 based on this command. The laser light 3 is condensed by the condenser lens 4 and is irradiated from the nozzle 5 onto the work 7 fixed to the table 6. The gap detector 8 is a capacitance-type distance detector, has a ring-shaped structure centering on the nozzle 5, and detects the capacitance between the workpiece 7 and the detection signal and outputs it. The detected capacitance corresponds to the amount of gap between the nozzle 5 and the work 7.

The detection signal is converted into a digital value by the A / D converter 14. The processor 11 reads this via the bus 10 and uses the correction coefficient to correct the level change caused by the difference in the material and surface condition of the work 7 and the aging and drift of the gap detector 8, and the distance detector 8 The gap amount between the nozzle 5 and the workpiece 7 is obtained by correcting the detection signal from the above, and the deviation amount is obtained by comparing this gap amount with a reference value, and a speed command proportional to the deviation amount is issued to the servo amplifier 15. .

The servo amplifier 15 has a built-in D / A converter, converts the speed command into an analog value and then amplifies it to drive the servo motor 9. The nozzle 5 moves in the Z-axis direction by driving the servo motor 9.
In addition to this, there is a servo system for controlling the table 6 in the X-axis direction and the Y-axis direction perpendicular to the paper surface. These are controlled in accordance with the axis movement command of the machining program, but these are omitted in this figure. is there.

A pulse coder 91 is attached to the servo motor 9, and a pulse signal is generated each time the servo motor 9 rotates by a predetermined angle. This pulse signal is input to the servo amplifier 15 as a feedback signal. As a result, while the nozzle 5 basically moves according to the machining program, the gap amount with the work 7 is kept constant by the gap control.

FIG. 1 shows a work 7 having a missing portion 71.
FIG. 6 is a conceptual diagram illustrating a gap control method according to the present invention when laser machining is performed. The work 7 has a plurality of laser processing areas, and in the processing program, a gap control ON command is set at the processing start point and a gap control OFF command is set at the processing end point for each laser processing area. .

First, prior to the execution of the machining program, the machining program is searched to find a gap control ON command for starting the gap control, and the nozzle 5 is positioned at the XY coordinate position when the gap control is ON. Then, the gap control is started to approach the nozzle 5
The nozzle 5 is moved in the Z-axis direction so that is at a predetermined distance from the surface of the work 7. This predetermined distance is a value set according to processing conditions such as the degree of narrowing of the irradiation spot of the laser light on the surface of the work.

When the approach is completed, the Z-axis coordinate value Z _OC of the nozzle 5 at that time is read and stored. Similarly, from the machining program, the next command for gap control ON is found, the nozzle 5 is positioned at the XY coordinate position when the gap control is ON, the approach is performed, and the Z axis coordinate value Z _OC of the nozzle 5 at that time is determined. A series of processes of reading is repeated throughout the machining program to read and store the Z-axis coordinate value Z _OC of the nozzle 5 when each gap control is turned on.

Next, the machining program is actually executed from the beginning. When there is a gap control ON command to start the gap control, the Z-axis coordinate value Z previously detected and stored.
_A corresponding value is read from _OC , and a clamp level Z _CL , which is the Z-axis coordinate value of the nozzle 5 where the nozzle 5 hits the work 7 and starts causing interference, is calculated. Details of this calculation will be described later.

After this calculation, laser processing is performed according to the processing program, for example, in the laser processing area (1), and at the same time, the gap control according to the present invention is performed. That is,
With the movement of the nozzle 5 in the XY directions, the position control of the nozzle 5 in the Z direction is performed so as to keep the gap amount between the workpiece 7 and the nozzle 5 constant, and the current value Z of the Z axis coordinate value of the nozzle 5 is set. _Are compared with the previously calculated clamp level Z _CL .

When the nozzle 5 reaches the workpiece missing portion 71 in FIG. 1, the current value Z of the Z-axis coordinate value of the nozzle 5 is reduced by the downward operation of the nozzle 5 in order to make the gap amount constant. descend. In this case, according to the present invention, the current value Z of the Z-axis coordinate value of the nozzle 5 is prevented from becoming a value below the clamp level Z _CL . That is, the tip of the nozzle 5 is the work 7.
The nozzle 5 is prohibited from moving downward (minus the Z-axis) immediately before it hits the workpiece 7 from the surface of the nozzle.

Then, when the nozzle 5 reaches the portion of the work 7 which is not the missing portion again, the nozzle 5 is held at a predetermined distance from the work 7. After that, when there is a gap control OFF command that should terminate the gap control, the gap control is terminated, and at the same time, the laser machining in the laser machining area (1) is terminated according to the machining program, and the nozzle 5 waits for a predetermined fast-forward. Move up to the position (Z-axis plus direction).

The execution of the machining program and the gap control according to the present invention as described above are repeated for each laser machining area. In addition, the Z-axis coordinate value Z _OC of the nozzle 5 when each gap control is turned on is read for each of a plurality of laser processing areas, and the clamp level Z _CL is calculated based on the read value to suppress the movement of the nozzle 5 in the Z direction. I am trying to do it. Therefore, even if the workpiece 7 is warped between the laser processing areas, the nozzles 5 can be prevented from interfering with the workpiece 7 because the Z-axis coordinate values Z _OC have already folded the warpage of the workpiece 7.

The above gap control method according to the present invention will be described in more detail with reference to a flowchart. FIG. 3 is a flowchart showing a procedure for reading and storing the Z-axis coordinate value Z _OC of the nozzle 5 when each gap control is turned on, and FIG. 4 shows the interference of the nozzle 5 with the work 7 when the machining program is actually executed. It is a flow chart which shows the procedure of gap control which prevents it. These flowcharts are stored in the ROM 12a of FIG. 2 and are executed by the processor 11. In the figure, the number following S represents a step number.

[S1] The entire machining program is read. [S2] The read machining program is searched to find the command for turning on the gap control. That is, it is determined whether or not a gap control ON command is issued when the nozzle 5 is positioned at the XY coordinate values updated in step S3. If the gap control ON command is issued, the process proceeds to step S4, and if not, the process proceeds to step S3.

[S3] The XY coordinate values are updated according to the machining program. [S4] If the gap control ON command is issued, the nozzle 5 is actually positioned at the XY coordinate value. [S5] The gap control is started, and the nozzle 5 is moved in the Z-axis direction so that the nozzle 5 is located at a predetermined distance from the surface of the work 7.

[S6] It is determined whether or not the nozzle 5 has reached a position at a predetermined distance from the surface of the work 7, that is, whether or not the approach has been completed. When the approach is completed, the process proceeds to step S7. [S7] The Z-axis coordinate value Z _OC of the nozzle 5 at the time when the approach is completed is read and stored in association with the XY coordinate value of the gap control ON in step S4.

[S8] The search in step S2 for all the commands for turning on the gap control included in the machining program and the Z-axis coordinate value Z _{OC in} step S7 based on the search.
It is determined whether or not the reading of is completed. If not completed, the process returns to step S1 and steps S1 to S7 are repeated, while if completed, the process proceeds to step S11 in FIG.

By executing the above steps S1 to S8,
The reading and storage of the Z-axis coordinate value Z _OC at the time of turning on each gap control, which should be performed in advance, are completed. Next, the actual machining program is executed according to the flowchart of FIG. [S11] The machining program read in FIG. 3 is returned to the initial position. [S12] The machining programs are sequentially read and decoded.

[S13] Read in step S12,
It is determined whether or not there is a gap control ON command in the decoded machining program portion. Only when the command to turn on the gap control is issued, the process proceeds to step S14. [S14] from among the Z-axis coordinate value Z _OC stored in step S7 of FIG. 3, reads XY coordinate values of the gap control ON by selecting the same Z-axis coordinate value Z _OC.

[S15] The clamp level Z _CL is calculated based on the following equation using the read Z-axis coordinate value Z _OC . Z _CL = Z _{OC −Z R} Here, Z _R is a clamp allowable value given as a variable, and if the warp of the workpiece 7 in each laser processing region is negligible, the nozzle 5 is held at a constant value. And work 7
Is set to a predetermined distance between. However, if the warp of the work 7 in each laser processing area is taken into consideration, a value obtained by subtracting the maximum value of the warp of the work 7 in each laser processing area from the predetermined distance between the nozzle and the work is given. , Z _R
You may set as.

[S16] Whether or not the gap control is off
To determine. If the gap control is on, step S1
7 to S19, while if the gap control is off
For example, skip steps S17 to S19 and skip step S
Go to 20. [S17] The current value Z of the Z-axis coordinate value of the nozzle 5 is detected.
And the clamp level calculated in step S15
Z_CLCompared to. Current value Z is clamp level Z _CLThan
Is larger, that is, the tip of the nozzle 5 is on the surface of the workpiece 7.
If it is above the surface, the nozzle 5 will not interfere with the work 7.
Therefore, the process proceeds to step S18. However, the current value Z
Ramp level Z_CLIf, that is, if the tip of the nozzle 5 is
If it is on the surface of work 7 or below the surface, nozzle
5 interferes with the work 7, so proceed to step S19.
Mu.

[S18] Normal gap control is performed. That is, control is performed to keep the gap between the nozzle 5 and the work 7 at a predetermined distance. [S19] The movement of the nozzle 5 in the negative Z-axis direction is clamped. That is, the position just before the tip of the nozzle 5 reaches the surface of the workpiece 7 is held, and the current value Z of the Z-axis coordinate value of the nozzle 5 is controlled to be a value slightly larger than the clamp level Z _CL .

[S20] Machining calculation is performed according to the machining program, and pulse distribution is performed. [S21] It is determined whether all the machining programs have been completed. If not completed, the process returns to step S12, and if completed, this program ends. As described in steps S11 to S21 above, in the case of normal processing in which the warp of the work 7 in each laser processing region can be ignored, the tip of the nozzle 5 is aligned with the surface of the work 7 in FIG. And moves in the XY directions while maintaining the Z-axis coordinate value Z _OC , and reaches the missing portion 71 of the work, it moves in the XY directions while maintaining a position slightly above the surface of the work 7. Then, the Z-axis coordinate value Z _OC is maintained again when it reaches a portion of the work 7 which is not the missing portion. In this way, the gap control in the laser processing area (1) is completed, and the nozzle 5 becomes the work 7.
Can be prevented from interfering with.

Similarly, when the Z-axis coordinate value Z _OC shifts to a different laser processing area (n), the different Z-axis coordinate value Z _OC.
The clamp level Z _CL is calculated based on _{OC, and} when the missing portion of the work is reached, the clamp level Z _CL is moved in the XY directions while maintaining a position slightly above the surface of the work 7. Thus, the nozzle 5 can be prevented from interfering with the work 7 even if the work is warped between the laser processing areas.

As shown by double brackets in FIG. 1, if Z _OC is regarded as the Z-axis coordinate value of the surface of the work 7, the clamp level Z
_CL can be represented by the position of the broken line, and the position of this broken line represents the clamp limit surface position of the workpiece 7 where the clamping is performed at the position below this.

[0036]

As described above, according to the present invention, in advance,
The clamp coordinate value for limiting the movement of the nozzle in the work direction is determined based on the distance from the work surface to the nozzle, and then when the nozzle moves in the XY directions relative to the work, the Z of the nozzle is determined. Since the movement of the nozzle in the Z-axis direction is controlled so that the coordinate value of the axis does not become smaller than the previously determined clamp coordinate value, the movement of the nozzle in the work direction is restricted by the clamp coordinate value, The nozzle is prevented from interfering with the work surface.

[Brief description of drawings]

FIG. 1 is a conceptual diagram illustrating a gap control method according to the present invention in the case of laser processing a work having a missing portion.

FIG. 2 is a schematic configuration diagram of hardware of a laser processing machine for carrying out the present invention.

FIG. 3 is a flowchart showing a procedure for reading and storing a Z-axis coordinate value Z _OC of a nozzle.

FIG. 4 is a flowchart showing a procedure of gap control when a machining program is actually executed.

[Explanation of symbols]

5 nozzles 7 work 71 Work missing part 8 Gap detector

Claims (4)

[Claims] 1. A gap control method for a laser processing machine, which processes the work while controlling the gap between the nozzle and the work to a constant value based on a detection signal from a gap detector provided in the nozzle, wherein When the nozzle is at a position of a predetermined distance suitable for performing laser processing from the surface of the work, the coordinate value of the Z axis of the nozzle is detected,
When the clamp coordinate value for limiting the movement of the nozzle in the work direction is determined based on the detected nozzle Z-axis coordinate value, and the nozzle moves in the XY directions relative to the work. A gap control method for a laser processing machine, wherein movement of the nozzle in the Z-axis direction is controlled so that the Z-axis coordinate value of the nozzle does not become smaller than the determined clamp coordinate value. 2. A gap control method for a laser processing machine, which processes the work while controlling the gap between the nozzle and the work to a constant value based on a detection signal of a gap detector provided in the nozzle. Add a gap control ON command for the laser machining start point and a gap control OFF command for the laser machining end point to the machining program including the laser machining process of When the nozzle reaches a position of a predetermined distance suitable for performing laser processing from the work surface, the Z-axis coordinate value of the nozzle is detected and stored, and then the processing program is started from the beginning. In each of the laser machining steps of the machining program executed, the work direction of the nozzle is determined based on the detected and stored Z-axis coordinate value of the nozzle. The clamp coordinate value for limiting the movement in the direction, and when the nozzle moves in the XY directions relative to the workpiece, the coordinate value of the Z axis of the nozzle is the determined clamp coordinate value. A gap control method for a laser beam machine, wherein each movement of the nozzle in the Z-axis direction is controlled so as not to become smaller than the above. 3. A gap control method for a laser processing machine, which processes the work while controlling the gap between the nozzle and the work to a constant value based on a detection signal from a gap detector provided in the nozzle. Add a gap control ON command for the laser machining start point and a gap control OFF command for the laser machining end point to the machining program including the laser machining step of Every time there is an instruction to turn on the gap control, the nozzle is positioned at the X / Y coordinate position at the time when the instruction to turn on the gap control, and each time the nozzle is positioned. , Start gap control to bring the nozzle to a position at a predetermined distance suitable for laser processing from the work surface. Therefore, every time the approach is performed, based on the detection signal, it is determined that the nozzle has approached the work,
Each time the determination is performed, the Z-axis coordinate value of the nozzle at that time is detected and stored, then the machining program is executed from the beginning, and when the machining program is executed,
Each time the command to turn on the gap control in each laser processing step is read, the stored Z-axis coordinate value of the nozzle corresponding to each laser processing step is read out, and each time the read out nozzle of the read nozzle is read out. The clamp coordinate value is determined by subtracting the predetermined distance from the Z-axis coordinate value, and when the nozzle moves in the XY directions relative to the workpiece in each of the laser processing steps, the Z of the nozzle is adjusted. The axis coordinate values are respectively compared with the corresponding determined clamp coordinate values, and the Z axis direction of the nozzle is adjusted so that the Z axis coordinate value of the nozzle does not become smaller than the corresponding determined clamp coordinate value. A method for controlling a gap in a laser processing machine, characterized in that the movement of each of the two is controlled. 4. When a gap control OFF command for each laser processing step is read during execution of the processing program,
When the clamp coordinate value used for the comparison up to that point is canceled and then the command for turning on the gap control of the next laser processing step is read, a new clamp coordinate value corresponding to this laser processing step is used for the comparison. The gap control method for a laser beam machine according to claim 3, wherein