JPH0422181A - Detecting system for abnormality of blower - Google Patents

Abstract

PURPOSE:To simply detect the abnormality of a blower and to prevent a working defect and the damage of the blower and the like by a method wherein the number of revolutions of the blower is detected, the difference between the number of revolutions and the normal number of revolutions is found, the blower is judged to be abnormal when the difference becomes a prescribed value or higher, the operation of the blower is stopped and an alarm is displayed on a display device. CONSTITUTION:A turboblower 20 is turned at high speed by using a high-frequency inverter 26; and the abnormality of the turboblower 20 is detected by using a tachogenerator 27 by means of its number of revolutions. The turboblower 20 circulates a laser gas 19 through coolers 21a and 21b. A shutter control circuit 22 opens and shuts a shutter 23a on the basis of the instruction of a processor 1. A laser beam which has been transmitted partially and output through a rear mirror 5 is input to a power sensor 24. The output power of a laser beam 7 is measured; and the output is converted into a digital value by using an A/D converter 25 and is input to the processor 1. Thereby, it is possible to accurately detect the abnormality of the blower.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for detecting an abnormality in a blower of a gas laser apparatus equipped with a mechanism for forcibly cooling laser gas using a blower and a cooler, and particularly relates to a method for detecting an abnormality in a blower for detecting an abnormality in the blower. Related to abnormality detection method [Prior art] Gas laser oscillators such as C02 gas lasers are highly efficient, provide high output, and have good beam characteristics, so they are widely used as gas laser devices combined with numerical control devices for metal processing, etc. Became. In such a gas laser oscillator,
In order to improve oscillation efficiency, it is necessary to sufficiently re-cool the laser gas that has become hot during laser oscillation. For this reason, the laser gas is constantly circulated within the apparatus through a cooler using a blower such as a turbo blower.

Further, since this blower normally requires high-speed rotation of 10,000 r'pm or more, a high-frequency motor is used, and a high-frequency inverter is used as a driving source.

[Problem to be solved by the invention]

The blower represented by this turbo blower is usually 10.00
It rotates at a high speed higher than Orpm. Therefore, if the bearings that hold rotating bodies such as impellers are not maintained properly, such as replenishing the bearings with new lubricant, the contact surfaces of the bearing balls and bearing link balls will peel off. , contact resistance increases.

When this contact resistance increases, the temperature of the contact portion increases, the rotational load increases, and rotation becomes unstable.

As a result, the flow of the laser gas becomes unstable and the laser output becomes unstable.

However, there are various reasons why the laser output becomes unstable, such as gas leaks from the ventilation system, abnormalities in the constant current control circuit of the laser gas excitation power supply, and deterioration of optical components inside the laser oscillator. However, it is necessary to perform complicated tests until it is determined that the problem is caused by an abnormality in the blower.

In addition, if fluctuations in laser output do not affect laser processing, if the operator does not notice that the rotation speed of the blower has decreased and continues to operate the laser device, the blower will be damaged and the bearings will need maintenance. This alone will lead to a situation that cannot be corrected.

The present invention has been made in view of these points, and it is an object of the present invention to provide a blower abnormality detection method that constantly detects the rotational speed of the blower and detects abnormalities in the blower.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a gas laser that is composed of a laser oscillator that cools the laser gas by forcedly circulating it in a closed loop using a blower and a gas cooler that are Vt-controlled by a high-frequency inverter, and a control device that controls the laser oscillator. In the abnormal pressure detection method of the blower of the device, the rotation speed of the blower is detected, the difference from the normal rotation speed obtained when the blower is operated under normal conditions is determined, and the difference exceeds a predetermined value. Provided is an abnormality pressure detection method for a blower, which is characterized in that when a blower is detected as abnormal, the blower is stopped, and alarm contents are displayed on a display at the same time.

C action] Detect the rotation speed of the blower and find the difference between this rotation speed and the normal rotation speed. When this difference exceeds a predetermined value, it is assumed that the blower is abnormal, the blower operation is stopped, and an alarm is displayed on the display device.

If the operator neglects to maintain the bearings of the blower and an abnormality occurs in the bearings, or if dust, etc. inherent in the blower system gets into the bearings and causes some kind of damage to the bearings. Also, monitor the rotation speed of the blower)
If so, abnormalities in the blower can be accurately detected.

〔Example〕

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

FIG. 2 is a block diagram showing the configuration of a gas laser device for implementing the present invention. In the figure, processor l
reads out the Niprogram stored in the memory 10 based on a control program stored in a ROM (not shown) and controls the operation of the entire gas laser apparatus. The output control circuit 2 has a built-in D/A converter,
The output command value output from the processor 1 is converted into a current command value and output. The excitation power supply 3 rectifies the commercial power supply and then performs a switching operation to generate a high frequency voltage.
A high frequency current according to the current command value is supplied to the discharge tube 4.

A laser gas 19 circulates inside the discharge tube 4, and when a high frequency voltage is applied from the excitation power source 3, a discharge occurs and the laser gas 19 is excited. The rear mirror 5 has a reflectance of 99.
The mirror made of 5% germanium (Ge) and the output mirror 6 are mirrors made of zinc selenium (ZnSe) with a reflectance of 65%.These constitute a Fabry-Perot type resonator, and the output mirror 6 is a mirror made of zinc selenium (ZnSe) with a reflectance of 65%. The 10.6 μm light is amplified and a part of it is outputted from the output mirror 6 as a laser beam 7 to the outside.

When a shutter 23a, which will be described later, is open, the output laser beam 7 changes its direction with a pendulum mirror 8, is focused into a spot of 0.2 mm or less by a condensing lens 9, and is irradiated onto the surface of the workpiece 17.

Memory] 0 is a nonvolatile memory that stores machining programs, various parameters, etc., and CMO 3, which has been backed up by memory, is used. In addition, there is a ROM for storing system programs and a RAM for temporarily storing data, but these are omitted in this figure.

A position control circuit 11 controls the rotation of a servo motor 13 via a servo amplifier 12 in response to a command from a processor 1, and controls the rotation of a servo motor 13 via a ball screw 14 and a nut 15.
6 and the position of the workpiece 17. Although the figure shows only one axis of the servo amplifier and servo motor, there are actually a plurality of control axes. Display device 1
8, a CRT or liquid crystal display device is used.

A turbo blower 20 is used as the blower, and the turbo blower 20 is powered by a high frequency inverter 26 to generate 81,000 yen.
Rotates at 0 rpm. Further, the turbo blower 20 is connected to a tacho generator 27 that detects the rotational speed.

The tacho generator 27 detects the rotation speed of the turbo blower 20 and is used to detect abnormalities in the turbo blower 20 based on the rotation speed, the details of which will be described later.

Further, an encoder or a resolver may be used instead of the tacho generator 27 to detect the rotation speed.

Furthermore, to detect the rotation speed, the gas flow rate can be measured by detecting the pressure difference between the suction side and the discharge side of the turbo blower 20, and the rotation speed of the turbo blower 20 can also be indirectly detected.

Turbo blower 20 circulates laser gas 19 through coolers 21a and 21b. The cooler 21a is a cooler for cooling the laser gas 19 which has become high temperature due to laser oscillation, and the cooler 21b is a cooler for removing compression heat caused by the blower 20.

The shutter control circuit 22 opens and closes the shutter 23a based on instructions from the processor 1. The shutter 23a is made of a copper plate or an aluminum plate whose surface is plated with gold, and when closed, the shutter 23a reflects the laser beam 7 output from the output mirror 6 and causes it to be absorbed by the beam absorber 23b. shutter 23
When opening a, the laser beam 7 is irradiated onto the workpiece 17.

The power sensor 24 is composed of a thermoelectric photoelectric conversion element, etc., and measures the output power of the laser beam 7 by manually inputting the laser beam partially transmitted and output from the rear mirror 5. The Δ/D conversion converter 5 converts the output of the power sensor 24 into a digital value and inputs it to the processor 1 manually. Here, the control device for controlling the laser oscillator is composed of a numerical control device.

FIGS. 1(a), (b), and (c) are flowcharts of a method for detecting an abnormality in a blower according to the present invention. In the figure, the number following S indicates the stamp number.

[S1] Vacuum pump (omitted in Figure 1).

) to lower the pressure inside the discharge tube 4.

[S2] Check whether the gas pressure inside the blower system has become 10 Torr or less, and proceed to S3.

[S3] Start pressure control.

[S4] Start operation of the turbo blower 20 [S5]
] Check whether the turbo blower 20 has reached the rated rotational speed of 81,000, and if it has reached the rated speed, proceed to S6.

[S6] The rotation speed of the turbo blower 20 is detected from the tacho generator 27, and abnormality detection is started. The abnormality detection process is 5IO1Sll.

[S7] Determine whether the pressure within the ventilation system has settled to 30 Torr or not, and if it has settled, proceed to S8.

[S8] Start discharging. Laser processing starts from here. In other words, while performing laser processing, SIO ~
The abnormality detection process of S12 is executed.

[S10] The rotation speed R1 of the cube blower 20 is read from the tachogenerator 27.

[S11] Check whether the absolute value of the difference between the detected rotation speed R1 and the normal rotation speed Rr of the turbo blower 20 is 200 rpm or more, and if so, proceed to S12. Note that the rotation speed of the turbo blower 20 is read at intervals of 16 m5ec.

[512:] Display the abnormality of the turbo blower 20 on the display device 18, and proceed to S21.

[S21] Discharge is stopped. That is, turbo blower 2
This is because there is an abnormality in the discharge tube 4, and if discharge continues as it is, there is a risk of damaging the discharge tube 4 and the like.

[522E Stop rotation of turbo blower 20.

That is, the output of the high frequency inverter 26 is turned off. Also, the pressure control of the laser gas is stopped, and the operation of the vacuum pump is also stopped.

[323] Start gas purge.

[524E Check for completion of gas purge, and when gas purge is completed, proceed to 325.

[525:] Inspect and repair the bearings of the turbo blower 20.

In the above description, an abnormality in the turbo blower is detected when the difference between the rotation speed of the turbo blower and the rated rotation speed exceeds a certain value, but an abnormality can also be detected by examining changes in this difference.

That is, there is fluctuation in the rotation speed of the turbo blower. The frequency components of these fluctuations are measured with the turbo blower in a normal state. During actual turbo blower operation, the frequency component of fluctuation within a predetermined time is detected, and if the frequency component has a frequency component other than the pre-measured frequency component in the normal state, it is regarded as an abnormality in the blower and the abnormality is detected. It can also be detected.

Further, in the above description, the blower is Turbo Pro, but it goes without saying that the present invention can also be applied to a blower such as a Roots blower.

Note that the above numerical values such as the rotational speed and the difference in rotational speed for detecting an abnormality are merely examples, and these numerical values are determined according to the actual laser device.

〔Effect of the invention〕

As explained above, in the present invention, an abnormality in the blower is detected by comparing the rotation speed of the blower with the rotation speed in a normal state. This can prevent damage such as

[Brief explanation of drawings]

FIGS. 1(a), (b), and (c) are flowcharts of an abnormality detection method for a blower according to the present invention, and FIG. 2 is a block diagram showing the configuration of a gas laser device for implementing the present invention. G Processor Discharge tube Memory Display device Turbo blower High frequency inverter Tacho generator

Claims (5)

[Claims] (1) In a method for detecting an abnormality in a blower of a gas laser device, which includes a laser oscillator that cools the laser gas by forced circulation in a closed loop using a blower driven by a high-frequency inverter and a gas cooler, and a control device that controls the laser oscillator, the method includes: The number of rotations of the blower is detected, the difference between the number of rotations and the normal number of rotations obtained when the blower is operated under normal conditions is determined, and if the difference exceeds a predetermined value, it is considered that the blower is abnormal and the blower is turned off. An abnormality detection method for a blower characterized by stopping the operation of the blower and simultaneously displaying alarm details on a display device. (2) A frequency component of fluctuation within a predetermined time is detected from the rotation speed, and if the frequency component has a frequency component other than the predetermined frequency component, it is regarded as an abnormality of the blower. Blower abnormality detection method. (3) The abnormality detection method for a blower according to claim 1, wherein the rotation speed of the blower is detected using a tachometer, an encoder, or a resolver provided inside the blower. (4) The detection of the rotational speed of the blower is characterized in that the gas flow rate is measured by detecting a pressure difference between the suction side and the discharge side of the blower, and the rotational speed of the blower is detected in a pseudo manner. An abnormality detection method for a blower according to item 1. (5) The abnormality detection method for a blower according to claim 1, wherein the control device is constituted by a numerical control device.