JPH07208369A - Deterioration monitoring device for vacuum pump - Google Patents

Abstract

PURPOSE:To provide a deterioration monitoring device for a vacuum pump which can previously senses deterioration of, especially pump oil, of a vacuum pump, and cope with it. CONSTITUTION:Driving current I of an electric motor for diving a vacuum pump is detected by a current detector 21. A mean value of current Is in a day is computed by a mean value computing means 22. An estimating means 23 estimates fluctuation of the future current I from hysterisis of the mean values. A margin period computing means 24 computes a margin period in which the estimated current I reaches a specified threshold value. In the case that the margin period is in a specified watching period, a first alarm means 25 generates alarm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deterioration monitoring device for a vacuum pump, and more particularly to a vacuum pump indirectly monitoring the deterioration of the vacuum pump based on a change in a driving-related amount such as a driving current of an electric motor for driving the vacuum pump. The present invention relates to a monitoring device for monitoring deterioration.

[0002]

2. Description of the Related Art Conventionally, for example, the deterioration of a vacuum pump used in an electron beam welding machine as an electron beam processing machine is inspected regularly or appropriately by an operator.

[0003]

However, in the above-mentioned conventional inspection method by the worker, there is a possibility that a problem such as an erroneous judgment due to the individual difference of the worker may occur. Also, for example,
It is difficult to detect the deterioration of the pump oil of the vacuum pump, the entry of foreign matter into the vacuum pump, and the increase in load due to the entry of foreign matter into the bearing part of the vacuum pump and the lack of grease. There is a risk that the vacuum pump will fall into an unrepairable state after a while, in which case
This causes a problem that the operating efficiency of the electron beam welding machine is lowered.

It is an object of the present invention to provide a deterioration monitoring device capable of predicting and coping with deterioration of a vacuum pump, particularly of pump oil.

[0005]

A vacuum pump deterioration monitoring apparatus according to the present invention is a vacuum pump monitoring apparatus for monitoring deterioration of a vacuum pump driven by an electric motor.
From the detection means for detecting the drive-related quantity of the electric motor, the average value calculation means for obtaining the average value of the detection quantity of the detection means for each predetermined unit period, and the history of the average values obtained by the average value calculation means. Prediction means for predicting a future change in the detected amount, margin period calculation means for obtaining a margin period until the detection amount predicted by the prediction means reaches a predetermined threshold value, and the margin period is a predetermined warning A first alarm means for issuing an alarm when it is within the period is provided.

[0006]

The deterioration monitoring device for a vacuum pump according to the present invention detects a drive-related amount such as a drive current of an electric motor for driving the vacuum pump, and from the history of the average value of the detected amount for each predetermined unit period, A margin period until the detected amount reaches a predetermined threshold is predicted, and an alarm is issued when the margin period falls within a predetermined warning period. Therefore, an alarm is issued by predicting the deterioration of the vacuum pump, especially the pump oil.

Further, in the case of a vacuum pump used in an electron beam welding machine, for example, the deterioration of the vacuum pump, particularly the pump oil, is predicted and the work efficiency of the electron beam welding machine is deteriorated or the welding quality is deteriorated. It is possible to avoid.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

This embodiment is an application example as a deterioration monitoring device for a vacuum pump for bringing a welding work chamber into a vacuum state in an electron beam welding machine for electron beam welding a work (workpiece W). . Therefore, first, the electron beam welding machine will be briefly described with reference to FIGS. 1, 2, 3, and 4.

[0010] "About electron beam welding machine" this example an electron beam welding machine, while rotating the workpiece W about the axis O ₁ of the vertical in a vacuum chamber (welding chamber) R, the axis O ₁ Electron beam E on top of work W
By irradiating B (see FIG. 2), the upper portion of the work W is continuously welded along its rotation direction. The vacuum chamber R is formed by a chamber chamber R ₁ and a column chamber R ₂ which are communicated with each other via an opening / closing valve 1. Inside the column chamber R ₂ , a filament 2 connected to a high voltage power source (not shown) is provided. It is equipped. Further, each of the chamber chamber R ₁ and the column chamber R ₂ is brought into a vacuum state by an individual exhaust system equipped with a vacuum pump. Below the chamber R ₁ , there is provided a lid 3 which is attachable to and detachable from the lower opening. In the case of this example, the lid 3 is
In the rotating body 4 which rotates about the vertical axis O ₂ ,
A total of four are arranged at equal intervals along the circumferential direction,
Depending on the rotation of the rotating body 4, the lid body 3 is alternatively positioned below the chamber R ₁ . Each lid 3 is movable up and down with respect to the rotating body 4, and a rotary table 5 on which the work W can be placed is further provided so as to be rotatable around an axis line in the vertical direction.

The lid 3 located below the chamber R ₁ is pushed up by the cylinder 6 and rises to close the lower opening of the chamber R ₁ as shown in FIG. further,
A rotary table 5 provided on the lid 3 is rotated by a driving force of an AC motor (electric motor) 7. That is, when the cylinder 6 extends upward, the rotary table 5
The upper end of the drive shaft 8 is connected to the lower end of the rotary shaft 5A of the drive shaft 8, and the drive shaft 8 is connected to the gears 10, 11, 12,
And is rotated by the motor 7 via the spline shaft 13. The gear 12 and the spline shaft 13 are spline-fitted to each other to transmit the rotational force of the motor 7 regardless of expansion and contraction of the cylinder 6.

After all, in the electron beam welding machine of this example, the rotary body 4 is rotated to sequentially position the four rotary tables 5 in the chamber R ₁ , so that the workpieces before the rotary tables 5 are welded to the rotary tables 5. It is possible to continuously mount W, weld the work W, and remove the work W after the welding is completed.

In FIG. 3, 15 and 16 are vacuum pumps provided in the exhaust system of the chamber R ₁ , and 17, 1
Reference numeral 8 is a vacuum pump provided in the exhaust system of the column chamber R ₂ . The vacuum pumps 15 to 18 are individually driven by dedicated electric motors. In FIG. 3, a three-phase electric motor (electric motor) for driving the vacuum pump 16 is indicated by reference numeral 19. The motor 19 is driven at a constant voltage.

The monitoring apparatus of this embodiment monitors deterioration of the vacuum pumps 15 to 18 in such an electron beam welding machine. In the following, a monitoring device for monitoring the deterioration of the vacuum pump 16 will be described as a representative.

"Regarding the monitoring device" The vacuum chamber R is evacuated each time the work W is repeatedly welded. The inside of the chamber R ₁ is brought into a vacuum state by operating the vacuum pumps 15 and 16, and the vacuum pump 16 is driven by the motor 19. The monitoring device 20 of this example is shown in FIG.
As shown in, a current detector (detection means) 21 for detecting a drive current of the motor 19 (a drive-related amount of the electric motor) is provided. In this example, a current transformer is used as the current detector 21. Hereinafter, the drive current of the motor 19 detected by the detector 21 is also referred to as “detection current I”. The detected current I increases in accordance with the increase in load caused by the deterioration of the vacuum pump 16. The cause of the deterioration of the vacuum pump is, for example, deterioration of pump oil due to repeated operation of the vacuum pump 16 during operation of the electron beam welding machine, intrusion of foreign matter into the pump 16, and foreign matter in the bearing portion of the pump 16. There is intrusion or lack of grease. Since there is a proportional relationship between the viscosity of the pump oil and the detected current I, in a normal state where foreign matter does not enter and insufficient grease is generated,
The detected current I changes according to the deterioration of the pump oil. Further, in the monitoring device of this example, as shown in FIG. 5, an average value calculation means 22, a prediction means 23, and a margin period calculation means 2 that function based on the detected current I of the current detector 21.
4, first and second alarm means 25 and 26, and display means 27 are provided. These functions will be described later together with the operation.

Next, the operation of the monitoring device will be described with reference to the flowcharts shown in FIGS. 6 and 7.

"Monitoring Operation" First, the current detector 21 samples the drive current I of the motor 19 for example every 100 msec (step S1), and the detected current I exceeds a predetermined comparison reference value I _MAX . Sometimes an abnormal alarm is generated (steps S2, S3, S4). Such an alarm function is achieved by the alarm unit 26A (see FIG. 5) of the second alarm unit 26 displaying the alarm content on the display unit 27A (see FIG. 5) such as a CRT in the display unit 27, for example. The threshold value setting unit 26B (see FIG. 5) performs the function of setting the comparison reference value I _MAX . The comparison reference value I _MAX is a value exceeding the fluctuation range of the drive current I when the vacuum pump 16 is normally loaded, and when the detection current I exceeds this reference value I _MAX , the pump 16
It is determined that an anomaly including deterioration has occurred. After that, the following (data processing of the detection current I) is performed. (Data processing of detected current I) First, every hour, every day,
And in order to calculate the average value of the detected current I for each month, the average value calculation means 22 performs the following calculation processing when they coincide with the elapsed time.

That is, when it coincides with the elapsed time of every hour, the average value (I-H) of the detected current I detected in the past hour is calculated in steps S5, S6 and S7, and As shown in FIG. 9, the data of the “time change graph” (time change graph in time unit) G ₁ displayed on the display unit 27A of the display means 27 is updated. The horizontal axis of the graph G ₁ is the date and time, and the vertical axis is the average value (I-H) for each hour. The graph G _{1 in} FIG. 9 shows that the electron beam welding machine is at rest for 2 hours and 4
It is a change graph when repeating continuous operation of time,
For example, after 1 hour has passed from 12:00 on the 31st, the electron beam welding machine is continuously operated for 4 hours, then stopped for 2 hours, and then again continuously operated for 4 hours. The upper limit in the graph G ₁ indicates the value of I _MAX .

Next, when it coincides with the elapsed time for each day,
In steps S8, S9, and S10, the average value (I-D) obtained by averaging the average values (I-H) for the past one day is calculated and displayed on the display unit 27A of the display unit 27 as shown in FIG. The data of “day-time change graph” (day-by-day time change graph) G ₂ is updated. The horizontal axis of the graph G ₂ is the month and day, and the vertical axis is the average value (ID) for each day. The graph G _{2 in} FIG. 9 shows that the electron beam welding machine is operating on weekdays
It is a change graph at the time of repeating operation for two days off on a weekday, such as a break on Sunday. For example, it is suspended for two days on June 7th and 8th, and then operated for five days. Further, the upper limit in Graph ₂ indicates the value of I _MAX .

Next, when it coincides with the elapsed time of every one month, in the steps S11, S12 and S13, the past 1
Average value (IM) that averages the average values (ID) for months
And the display unit 2 of the display means 27 is calculated as shown in FIG.
It is displayed in 7A - (aging graph monthly) "month aging graph" updates the data in the G _3. The horizontal axis of the graph G ₃ is the year and month, and the vertical axis is the average value (IM) for each month. The upper limit in this graph G ₃ indicates the value of I _MAX .

Further, when the elapsed time coincides with each day, future changes in the average value (ID) for each day are predicted (see FIG. 7).

That is, the average value (I-D) of the latest day and the average value (I-D) of 30 days ago are read as A and B, respectively (steps S15 and S16), and the alarm allowable upper limit value C which will be described later is set. The number of warning days (warning period) D is read (steps S17 and S18). Then, the prediction means 2
3 (see FIG. 5) obtains the average change amount Z per day by the following equation (1) (step S19).

[0023]

[Equation 1]

Further, based on the assumption that the average change amount Z will continue in the future, the marginal period calculating section 24A (see FIG. 5) of the marginal period calculating means 24 (see FIG. 5) calculates a future average value (I-
The simple arrival days (margin period) E until D) reaches the upper limit value C is obtained by the following equation (2) (step S23).
The setting function of the upper limit value C is performed by the threshold value setting unit 24B.
(See FIG. 5).

[0025]

[Equation 2]

For example, at the latest date a in FIG. 8, the average value (ID) of the latest date a is (A-a), and the average value of the day 29 days before that (a-29). (ID) to (B
As -a), the simple arrival days (E-a) from the above equations (1) and (2) to the upper limit value C are predicted. The latest day b
At the time point of, the average value (ID) of the latest day b is (A-
b), and the average value (ID) of the day (b-29) 29 days before that is defined as (Bb), and the above equations (1), (2)
To the upper limit value C, the simple arrival days (E-b) will be predicted. By the way, as shown in FIG. 8, the average value (I-
The increase in D) means that the pump 16 has deteriorated. Therefore, determining the simple arrival days E is
The number of days until the deterioration of the pump 16 progresses to an extent corresponding to the upper limit C will be predicted.

Thereafter, if the number E of simple arrival days is within the number D of warning days, an alarm is issued to report the deterioration of the pump 16 (steps S21 and S22). As described above, the warning function when the simple arrival days E reaches the warning days D is displayed by the warning unit 25A (see FIG. 5) of the first warning unit 25, for example, the display unit 2
This is achieved by displaying the content of the alarm on the display unit 27A of No. 7, and the setting function of the number of warning days D has
(See FIG. 5). Then, the data of the deterioration prediction graph G _{4 which} will be described later is updated (step S2).
3).

The display means 27 will now be described.

The display means 27 is a display unit 2 such as a CRT.
7A, and the display content is displayed by the display content switching unit 27.
It can be switched by B. The display screen is a screen for vacuum pump motor current monitoring that displays four graphs as shown in FIG. 9, an enlarged drawing for individually enlarging and displaying these four graphs, and a vacuum pump motor as shown in FIG. There are a current value deterioration prediction screen and a threshold (I _MAX ) setting screen. Graph G _{0 in} FIG.
Is for sequentially displaying and monitoring changes in the detected current I. Further, the screen of FIG. 10 includes a graph G ₄ showing the history of the average value (ID) as shown in FIG. 8, the alarm output setting date as the warning days D, the change operation screen, and the simple arrival days E. Is displayed.

By the way, as described above, since there is a proportional relationship between the viscosity of the pump oil and the detected current I, in a normal state where there is no invasion of foreign matter or lack of grease, the pump oil will be deteriorated. As a result, the detection current I changes. Therefore, obtaining the simple arrival days E predicts the number of days until the deterioration of the pump oil progresses to an extent corresponding to the upper limit value C, and the replacement time of the pump oil can be grasped.

In the above embodiment, the drive current of the electric motor 16 driven by the constant voltage is detected as the drive-related quantity and the drive current is monitored. However, the electric motor 16 is driven by the constant current. In that case, the drive voltage may be detected as a drive-related amount and monitored. Also,
When both the drive current and the voltage fluctuate, the power may be detected as the drive-related quantity and monitored.

[0032]

As described above, the deterioration monitoring device for a vacuum pump according to the present invention detects a drive-related amount such as a drive current of an electric motor for driving a vacuum pump, and a predetermined unit period of the detected amount. From the history of the average value for each, it is configured to predict the margin period until the detection amount reaches a predetermined threshold value, and to issue an alarm when the margin period falls within a predetermined warning period. It is possible to predict the deterioration of the vacuum pump, especially the pump oil, and issue an alarm.

Therefore, for example, in the case of a vacuum pump used in an electron beam welding machine, the deterioration of the vacuum pump, particularly the pump oil, is predicted and the work efficiency of the electron beam welding machine is deteriorated or the welding quality is deteriorated. Can be avoided in advance.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a work rotation drive system of an electron beam welding machine provided with a monitoring device of the present invention.

FIG. 2 is a schematic configuration diagram of a vacuum chamber in the electron beam welding machine shown in FIG.

FIG. 3 is a side view of the entire electron beam welding machine shown in FIG.

4 is an explanatory diagram of a drive current detection circuit of the electric motor shown in FIG.

FIG. 5 is a block diagram showing an embodiment of the present invention.

FIG. 6 is a flow chart for explaining the operation of the embodiment of the present invention.

FIG. 7 is a flow chart for explaining the operation of the embodiment of the present invention.

FIG. 8 is an explanatory diagram of operations of a prediction unit and a margin period calculation unit shown in FIG.

9 is a front view of a display screen for explaining an example of display contents on the display unit shown in FIG. 4. FIG.

10 is a front view of a display screen for explaining another example of the display contents on the display unit shown in FIG.

[Explanation of symbols]

 R vacuum chamber (welding work room) W work (workpiece) EB electron beam 15, 16, 17, 18 vacuum pump 21 current detector (detection means) 22 average value calculation means 23 prediction means 24 margin period calculation means 25 1 warning means 26 2nd warning means 27 display means

Claims (6)

[Claims] 1. A vacuum pump monitoring device for monitoring deterioration of a vacuum pump driven by an electric motor, comprising: detection means for detecting a drive-related amount of the electric motor; and a predetermined detection amount of the detection means. An average value calculating means for obtaining an average value for each unit period, a predicting means for predicting a future change of the detection amount from a history of the average values obtained by the average value calculating means, and a detection amount predicted by the predicting means Is provided with a margin period calculation means for obtaining a margin period until the threshold value reaches a predetermined threshold value, and a first alarm means for issuing an alarm when the margin period falls within a predetermined warning period. Deterioration monitoring device for vacuum pumps. 2. The predicting means assumes that the degree of change between the past average value and the latest average value before the predetermined period, which is obtained by the average value calculating means, will continue in the future.
The deterioration monitoring device for a vacuum pump according to claim 1, wherein the deterioration monitoring device predicts a future change in the detected amount. 3. The deterioration of the vacuum pump according to claim 1, further comprising second alarm means for issuing an alarm when the detection amount of the detection means exceeds a predetermined threshold value. Monitoring equipment. 4. The vacuum according to claim 1, further comprising display means for displaying a calculation result of the average value calculation means and the margin period calculation means and a prediction result of the prediction means. Pump deterioration monitoring device. 5. The electric motor is driven by a constant voltage, and the detecting means detects a drive current of the electric motor as the drive-related amount. Alternatively, the deterioration monitoring device of the vacuum pump according to item 4. 6. The vacuum pump is provided in an electron beam processing machine, and exhausts a processing chamber of the electron beam processing machine to create a vacuum state.
The deterioration monitoring device for a vacuum pump according to 2, 3, 4 or 5.