JPH02179377A - Laser beam machining device - Google Patents

Abstract

PURPOSE:To simplify the operation and to shorten machining time by outputting laser light at a required output level to start boring and ending the boring at the point of the time when the reflected laser light decreases to a prescribed value or below upon penetration of the hole. CONSTITUTION:A reflected light detecting means which detects the level of the reflected laser light 11 to be fed back into a laser oscillator by the reflection on a work 10 surface and a detecting means which detects the time when the level of the reflected laser light 11 falls down to the prescribed value or below are provided. The boring is started by outputting the laser light at the required output level. The reflected laser light fed back in the laser oscillator decreases to the prescribed value or below when the hole is penetrated. This time is detected by the detecting means and the boring stage is ended. The next stage is started in succession thereto. The need for resetting the execution time is eliminated in this way even if the work material is changed. The operation is simplified and the machining with specified quality is possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser processing device that processes a workpiece by irradiating a laser beam, and in particular detects the point at which drilling is completed and transfers from the drilling process to the next process. Related to automated laser processing equipment.

[Conventional technology]

Laser processing equipment performs processing by irradiating a single point on a workpiece with laser light through a condenser lens, increasing the temperature of the irradiated area, and further evaporating the workpiece. First, if you irradiate the workpiece while it is stopped, it will create a hole (piercing).
will be carried out. If the workpiece is moved continuously after this, the workpiece will be cut.

By the way, when the hole penetrates, the workpiece is no longer irradiated with laser light, so the temperature of the workpiece decreases rapidly. For this reason, for example, in the case of a metal workpiece, approximately 10 minutes after drilling is completed.
When more than 0 milliseconds have elapsed, the absorption rate of the laser beam decreases,
Even if the workpiece is moved after that, good cutting cannot be performed.

Therefore, especially in the case of cutting, it is necessary to move the workpiece as soon as possible after completion of drilling (transfer to the cutting process and start moving the workpiece).

In conventional laser processing equipment, the execution time of the drilling process is set by an operator estimating the time required to actually complete drilling based on conditions such as the material of the workpiece and the plate thickness.

[Problem to be solved by the invention]

However, with conventional laser processing equipment, the operator needs to reset the execution time of the drilling process every time the material, plate thickness, surface condition, etc. of the workpiece change. Furthermore, if operators have different judgment criteria, processing quality will be affected.

The present invention has been made in view of these points, and it is an object of the present invention to provide a laser processing device that automates the detection of the completion point of drilling and the transition operation from the drilling process to the next process.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a laser processing apparatus that outputs a laser beam, irradiates it onto the surface of a workpiece, and processes the workpiece, in which a reflected laser beam is reflected back into a laser oscillator by reflection on the surface of the workpiece. reflected light detection means for detecting the level of the reflected laser light; detection means for detecting the point in time when the level of the reflected laser light has decreased below a predetermined value; and outputting the laser light at a required output level to start drilling, A laser processing apparatus is provided, comprising: command means for terminating the drilling process when the level of the reflected laser light decreases to a predetermined value or less, and continuously outputting a command for the next process. Ru.

[Effect]

The drilling process is started by outputting a laser beam at the required output level. When the hole penetrates, the amount of reflected laser light that is fed back into the laser oscillator is reduced to a predetermined value or less. This point is detected by the detection means, the drilling process is completed, and immediately the next process, for example, the workpiece is moved and cutting is performed. This minimizes the decrease in the temperature of the workpiece during process transition.

〔Example〕

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

FIG. 1 is a block diagram of a laser processing apparatus using a CO2 gas laser oscillator according to an embodiment of the present invention. In FIG. control the whole thing. The output control circuit 2 converts the output command value outputted from the processor 1 into a current command value and outputs the same, and has a built-in DA converter that converts a digital value into an analog output. After rectifying the commercial power source, the laser power source 3 outputs a high frequency voltage according to a command from the output control circuit 2.

Laser gas circulates inside the discharge tube 4, and when a high frequency voltage is applied from the laser power source 3, a discharge is generated and the laser gas is excited. Rear mirror 5 has a reflectance of 99.5%
germanium (Ge) mirror, output mirror 6 has a reflectance of 65
% zinc selenium (Znse), these mirrors constitute a Fabry-Perot type resonator, amplify the 10.6 μm light emitted from the excited laser gas molecules, and send a portion of it to the laser beam from the output mirror 6. Output to the outside as 7.

The direction of the laser beam 7 is changed by a pendulum mirror 8, and the laser beam 7 is condensed into a spot of 0.2 mm or less by a condensing lens 9, and is irradiated onto the surface of a workpiece 10. Reference numeral 11 denotes a reflected laser beam reflected by the surface of the workpiece 10, which passes through the condenser lens 9, the pendulum mirror 8, and the output mirror 6, and returns into the discharge tube 4 again.

The memory 12 is a memory that stores the program, parameters, etc., and is connected to the battery-backed CMO3.
etc. are used. The position control circuit 13 decodes the position command value output from the processor 1, controls the rotation of the servo motor 15 via the servo amplifier 14, controls the movement of the table 18 using the ball screw 16 and nut 17, and controls the movement of the workpiece 10. Control position. The display device 19 has C
An RT or liquid crystal display device is used.

A monitor laser beam 20 is output from the rear mirror 5 with a transmittance of 0.5%, and the output level, that is, the monitor value, is measured by the power sensor 21. A thermoelectric or photoelectric conversion element or the like is used for the power sensor 2■.

The output of the power sensor 21 is amplified and digitally converted by an amplifier 22, and then output to the processor 1.

FIG. 2(a) shows the change over time in the monitor value Pa during drilling. The axis represents the monitor value Pa, and the horizontal axis represents time. When the output of the laser beam is started at the output command value Pc from time to, the monitor value Pa increases to nearly twice the output command value in a short time due to the reflected laser light from the workpiece surface. Thereafter, the workpiece is heated and the absorption rate of the laser beam increases, so the monitored value Pa gradually decreases. Time t1
When the drilling is completed, the monitor value Pa rapidly decreases and becomes approximately equal to the output command value Pc.

The processor 1 inputs this monitor value Pa via the power sensor 21 and the amplifier circuit 22, and calculates the reflectance of the workpiece to the laser beam.

FIG. 2(b) is a graph showing changes in reflectance over time. In this way, the reflectance rapidly decreases from QO to Q2 after time t1 when drilling is completed. Therefore, by providing a threshold value at these intermediate points, it is possible to detect the point in time when drilling is completed. In this embodiment, this threshold value is set to 10%. In the case of cutting, the drilling process is first started, and when the reflectance drops to 10% or less, the process moves to the cutting process and the movement of the workpiece is started.

FIG. 3 is a flowchart of processing during cutting in a laser processing apparatus according to an embodiment of the present invention.

In the figure, the number following S represents the step number.

[S1] Decipher the drilling process command of the Canadian program.

[S2] Start the drilling process.

[S3] It is determined whether the reflectance has decreased to 10% or less. If it has decreased, the process proceeds to S4; if it has not decreased, the drilling process continues.

[S4] End the drilling process.

[S5] The cutting process command is deciphered.

[S6] Execute the cutting process.

Note that although the case of cutting has been described here, after the drilling process is completed, it is also possible to move to another drilling process.

Further, the threshold value of the reflectance described above is just an example, and is changed depending on the material of the workpiece.

〔Effect of the invention〕

As explained above, the present invention detects a decrease in the reflected laser light from the workpiece and automatically ends the drilling process and moves on to the next process, so even if the material of the workpiece is changed, the operator can There is no need to reset the execution time of the drilling process, which simplifies the operation. Furthermore, processing can be performed with a constant quality regardless of the skill level of the operator. Furthermore, machining time can be shortened since the next step can be performed in the shortest drilling time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a laser processing apparatus according to an embodiment of the present invention. FIG. 2(a) is a graph showing changes over time in monitor values during drilling in an embodiment of the present invention. (b)
3 is a graph showing changes over time in the reflectance of the workpiece with respect to laser light in an embodiment of the present invention. FIG. . 1-・-1--------- Processor 5...
−・・・−・−Rear mirror 6−−−−−−−・−・・−Output mirror 7−・−−・−・Laser beam 0−・−・・・・・・・・・・・Work 1−・−・−・
−・−Reflected laser beam 0−・−・−・−・・−Monitoring laser beam 1−・・・・・
......-Power sensor a--・------Monitor value C----Output command value during drilling 0...-- ...Drilling start time 1.
−・・・・・−−−1−−−−Drilling completion time Patent applicant Fanuc Co., Ltd. agent Patent attorney Takeshi Hattori Figure 2 (0) Figure 2 (b)

Claims (4)

[Claims] (1) In a laser processing device that outputs a laser beam and irradiates the workpiece surface to process the workpiece, reflected light detection detects the level of the reflected laser beam that is reflected back into the laser oscillator by reflection on the workpiece surface. means for detecting when the level of the reflected laser beam decreases to a predetermined value or less; outputting the laser beam at a required output level to start drilling processing until the level of the reflected laser beam decreases to a predetermined value; A laser processing device comprising: command means for terminating the drilling process when the number of holes decreases below a value and outputting a command for the next process. (2) The reflected light detection means detects the level of the reflected laser light by inputting the monitoring laser light transmitted from the rear mirror of the laser oscillator. laser processing equipment. (3) The laser processing apparatus according to claim 1, wherein the next step is a cutting step using the hole made by the hole drilling as a starting point. (4) The laser processing apparatus according to claim 1, wherein the next step is another drilling step.