JPH10137954A - Feedback control device for laser output - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent control errors and to improve cost effectiveness by controlling laser generator output, based on the quantity of heat imparted to a cooling medium in the cooling means by means of a laser beam during the interruption of machining such as attaching/detaching of a work. SOLUTION: In laser beam machining on a work W, in order to avoid irradiation to the machining position during the attaching and detaching of the work W in the position, a beam damper 3 which is a cooling means and a shutter mirror 4 whose opening/closing is controlled are provided between the laser generator 1 and the work W, with the laser beam R reflected to the beam damper 3 by closing the mirror 4. Simultaneously, with cooling water circulated in the beam damper, using a temperature sensor 31, 32 and a flow sensor 33 attached to the feed water pipe 51 and the distributing pipe 52, the quantity of heat is determined that are imparted to the cooling water by emitting the laser beam R to the beam damper 3. From this quantity of heat, an output controller 2 operates the output of the laser generator 1, controlling the feedback so that the output is equalized to a preset value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feedback control device for maintaining the output of a laser oscillator at a predetermined value.

[0002]

2. Description of the Related Art As a conventional apparatus of this kind, a beam splitter for transmitting only a few percent of irradiated laser light and reflecting the rest is provided obliquely in front of a laser oscillator for outputting laser light. There is known a device in which the laser beam is converted into an electric signal by a photoelectric sensor or the like and the output of the laser beam is feedback-controlled.

[0003]

SUMMARY OF THE INVENTION In the above prior art,
Since the beam splitter is expensive, there is a problem that the cost of the entire apparatus increases. Also, if dust adheres or becomes cloudy on the surface of the beam splitter, the transmittance may decrease, and conversely, the transmittance may increase due to so-called burning due to aging. Problem.

In view of the above problems, an object of the present invention is to provide a feedback control device for laser output.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a cooling means for circulating a refrigerant inside a laser oscillator for outputting a laser beam, and a laser for making the laser beam unnecessary. In a device provided with a shutter mirror that bends the output direction of light and irradiates the cooling unit with laser light, a temperature detecting unit that detects the temperature of the refrigerant of the cooling unit is connected to a control device that controls the output of the laser oscillator, The output of the laser oscillator is obtained based on the temperature of the refrigerant while the cooling means is being irradiated with the laser light, and the output is controlled so that the output of the laser oscillator becomes a set value.

[0006] When processing a work with laser light, the work cannot be irradiated with laser light when the work is attached or detached. On the other hand, if the laser oscillator is intermittently oscillated, it takes time from the start of oscillation to stabilization, so that the work cycle time of the work becomes longer, the efficiency of the laser oscillator becomes worse, and the life of the laser oscillator becomes shorter. Therefore, it is necessary to oscillate the laser oscillator continuously and irradiate the laser beam from the laser oscillator even when the work is attached or detached. Therefore, when the laser light is unnecessary, the cooling means is irradiated with the laser light by the shutter mirror. Since the cooling means is irradiated with the laser light, the temperature of the refrigerant circulating in the cooling means increases in proportion to the output of the laser light. Therefore, the output of the laser oscillator can be obtained from the temperature of the refrigerant.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a laser oscillator, and a workpiece W located in front of the laser oscillator 1 is shown.
The workpiece W is processed by irradiating the workpiece W with a laser beam R. The output of the laser oscillator 1 is controlled by an output control unit 2.
The output control unit 2 controls the AC supplied from the AC power supply 21 to 2
It is converted to a direct current of about 400 V and applied to the laser oscillator 1. On the other hand, the work W is removed from the front position of the laser oscillator 1 when the processing by the laser light R is completed by a not-shown transer device such as a conveyor, and the next unprocessed work W is the processing position of the laser oscillator 1. It is carried forward. As described above, the laser beam R must not be applied to the processing position while the work W is being attached to and detached from the processing position.
Therefore, between the laser oscillator 1 and the work W, a beam damper 3 as a cooling means and a shutter mirror 4 whose opening and closing are controlled by a control device are provided. When the work W is attached or detached, the laser beam R is reflected by the shutter mirror 4 and is irradiated to the beam damper 3 by closing the shutter mirror 4. Water supplied from the water absorption pipe 51 as a refrigerant circulates in the beam damper 3 and is discharged through the water distribution pipe 52. A temperature sensor 31 and a flow rate sensor 33 are attached to the water absorption pipe 51, and a temperature sensor 32 as temperature detection means is attached to the water distribution pipe 52. Then, the temperature sensors 31 and 32 and the flow rate sensor 33
Is input to the output control unit 2.

Next, referring to FIG. 2, the output control unit 2 keeps the shutter mirror 4 closed while the work W is being attached and detached, so that the outlet water temperature of the beam damper 3 detected by the temperature sensor 32 becomes high temperature H. However, when the attachment / detachment of the work W is completed, the control device opens the shutter mirror 4 and the outlet water temperature becomes low temperature L. Then, when the shutter mirror 4 is closed again, the outlet water temperature rises to H. Here, in the present embodiment, when the attachment / detachment of the work W is completed and the laser processing is started, it takes about 10 seconds until the outlet water temperature decreases and becomes stable. In addition, when the laser processing is completed and the work W is started to be attached / detached, the outlet water temperature rises to about 1 till darkening occurs.
It takes 0 seconds. Therefore, the output control unit 2 captures the outlet water temperature 10 seconds after the start of attachment / detachment of the work W, and obtains the beam damper 3 from the difference between the detected temperature from the temperature sensor 31 provided in the water suction pipe 51 and the detected flow rate from the flow rate sensor 33. The amount of heat transferred to the circulating water is determined. Since the heat quantity is proportional to the output of the laser oscillator 1, the output control unit 2 calculates the output of the laser oscillator 1 from the heat quantity and performs feedback control on the output of the laser oscillator 1 so that the output becomes a preset value. I do.

Since the laser beam R is not irradiated on the beam damper 3 during the laser processing, the low temperature L of the outlet water temperature detected by the temperature sensor 32 becomes substantially equal to the water temperature in the water absorption pipe 51 detected by the temperature sensor 31. Therefore, the difference between the high temperature H and the low temperature L among the detected temperatures of the temperature sensor 32 may be used as the temperature difference without providing the temperature sensor 31. If the flow rate of the circulating water is constant and does not fluctuate, the flow rate sensor 33 need not always be provided to detect the flow rate if the flow rate is known.

[0010]

As is apparent from the above description, the present invention performs feedback control on the output of the laser oscillator based on the temperature of the refrigerant circulating in the cooling means, and thus performs feedback control using a conventional beam splitter. It is cheaper and does not age.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a timing chart showing a change in outlet water temperature of a beam damper due to opening and closing of a shutter mirror;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser oscillator 2 Output control part 3 Beam damper (cooling means) 4 Shutter mirror 31 Temperature sensor 32 Temperature sensor 33 Flow rate sensor

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Rikuo Kato 1-10-1, Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Haruhiko Saito 1-10-1, Shinsayama, Sayama City, Saitama Prefecture Hong Da Engineering Co., Ltd.

Claims (1)

[Claims] 1. A cooling means for circulating a cooling medium in front of a laser oscillator for outputting a laser beam, and irradiating the cooling means with a laser beam by bending the output direction of the laser light when the laser light is unnecessary. In a device provided with a shutter mirror, a temperature detecting means for detecting the temperature of the refrigerant of the cooling means is connected to a control device for controlling the output of the laser oscillator,
A laser characterized in that an output of a laser oscillator is obtained based on a temperature of a refrigerant in a state where laser light is irradiated to a cooling unit, and the output is controlled so that an output of the laser oscillator becomes a set value. Output feedback control device.