JP7497633B2 - Maintenance timing determination system - Google Patents

Description

The present invention relates to a maintenance timing determination system for various parts, etc., on a production line, etc.

In typical manufacturing lines, various sensors are used to detect abnormalities. For example, in Patent Document 1, an abnormality is detected using an acoustic/vibration sensor that analyzes the sound and vibration generated from the manufacturing line and judges the abnormality based on the frequency spectrum. In these manufacturing lines, there are always consumable parts and oil, and the maintenance period is checked using a sensor. In addition, in [0013] to [0014] of Patent Document 2, an acoustic/vibration sensor is used that detects the sound caused by oil shortage in order to know the period for maintenance such as lubrication.

International Publication No. 2006/043511 Japanese Patent Application Laid-Open No. 9-260465

However, it is difficult to detect rust or oil shortage using an acoustic/vibration sensor. For example, when a gear tooth is damaged, a specific sound/vibration occurs when the damaged tooth meshes with another gear tooth in response to the rotation speed of the rotating shaft, and the period of the sound/vibration is synchronized with the rotation speed of the damaged gear. However, in the case of rust or lubricating oil shortage (hereinafter referred to as "oil shortage"), a specific period may not be detected, and Patent Document 2 [0014] describes that oil shortage is judged to occur when a sound with a frequency different from the frequency of the sound generated under normal conditions is generated. However, it is difficult to detect the sound/vibration that is a sign of oil shortage by separating it from noise, although it is different if the oil has completely run out and the condition becomes fatal. In addition, false detection is likely to occur due to unrelated sound/vibration, such as when a loud sound is heard nearby.
In order to prevent false positives, it is possible to increase accuracy or provide a compensation mechanism, but this is costly and it is difficult to completely prevent false positives.
As a result, decisions about when maintenance should be performed had to be based on the experience of the workers operating the production line.

Therefore, the objective of the present invention is to provide a new maintenance timing determination system.

In order to solve such problems, the present invention provides a maintenance timing determination system that includes an occurrence count detection unit, an occurrence frequency detection unit, and a discrimination unit, the occurrence count detection unit counting the occurrence number of alarm signals detected by a sensor within a predetermined first unit time, the occurrence frequency detection unit counting the occurrence number of alarm signals detected within a second unit time obtained by dividing the first unit time into smaller unit times, and the discrimination unit outputting a maintenance timing determination result when a first state occurs in which the occurrence number of the alarm signal detected within the first unit time is equal to or greater than the first number, and (1) a second state occurs in which the occurrence number of the alarm signal detected within a second unit time is equal to or greater than the second number, or (2) a third state occurs in which the occurrence numbers of the alarm signal detected within each of consecutive second unit times are equal to or greater than the third number.

It is now possible to determine when maintenance is required.

Overall configuration diagram of the embodiment FIG. 1 is an explanatory diagram of the number of occurrences of an alarm signal in an embodiment. (A) A graph showing the number of occurrences detected in a first unit time. (B) A graph showing the number of occurrences detected in a second unit time.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings indicate parts having the same function, and duplicated descriptions in each drawing will be omitted as appropriate.

(Example)
The embodiment is a maintenance timing determination system 1 for a power transmission system 7 that uses an acoustic/vibration sensor 6 as an abnormality detection sensor. Since a production line usually has various power transmission systems 7, a large number of acoustic/vibration sensors 6 (abnormality detection sensors) are provided, and each of them independently monitors a specific power transmission system 7.
FIG. 1 is an overall configuration diagram of an embodiment. An acoustic/vibration sensor 6 (anomaly detection sensor) is provided at an appropriate location of a power transmission system 7. The acoustic/vibration sensor 6 (anomaly detection sensor) constantly sends acoustic/vibration data 61 to an analysis unit 63. The analysis unit 63 analyzes the acoustic/vibration data 61, and in this embodiment, the frequency and power spectrum density are analyzed by short-time FFT. The analysis in the analysis unit 63 is not limited to FFT, and an orthogonal transformation such as a wavelet transform that analyzes frequency and period may be used. The analysis unit 63 is input with a frequency capable of detecting a failure or a possibility of failure in advance, and when the power spectrum density value of the frequency or period becomes equal to or greater than a threshold value, it outputs an alarm signal 631 to an alarm unit 62. For example, when a tooth of a gear 71 is scratched, sound and vibration occur with each rotation period of the gear, and by detecting the period together with the frequency of the sound, it is possible to detect which gear is abnormal. In addition, if there is a scratch on a bearing, sound and vibration occur with a period specific to each component constituting the bearing, such as a ball, an inner ring, and an outer ring.

These detections are also performed through general acoustic and vibration analysis.
In the following, to avoid confusion, the warning signal 631 regarding the detection result indicating signs of oil shortage that is sent to the maintenance timing determination system 1 will be referred to as the "oil shortage warning signal 6311", and warning signals based on other troubles will be referred to as "631" to distinguish them.
The signs of oil shortage, which are the detection target of the embodiment, often do not have a specific period or frequency. For example, the period or frequency differs depending on which gear 71 of the power transmission system 7 is running out of oil, and further, the period or frequency differs depending on the rotation speed at that time. Therefore, the analysis unit 63 of the embodiment is configured to determine that there is a sign of oil shortage when a sound or vibration other than the frequency or period caused by other causes input in advance and having a frequency or period different from the frequency of the sound generated under normal conditions is generated. The maintenance time determination system 1 is configured to receive only the oil shortage warning signal 6311 sent from the analysis unit 63. Note that the analysis unit 63 may be configured not to send warning signals 631 other than oil shortage, for example, warning signals 631 when a specific gear is flawed, to the maintenance time determination system.

Conventionally, when the analysis unit 63 of the sound/vibration sensor 6 (anomaly detection sensor) detects a sign of oil shortage, it sends an oil shortage warning signal 6311 to the alarm unit 62 and also sends an alarm signal 631 to the production line control device 8 to stop the production line. As mentioned above, it is difficult to detect oil shortage, and workers who receive an oil shortage warning often press the restart button 81 to restart the machine without checking, as there is a high possibility that it is a false detection. If such restarts are repeated, it will eventually develop into a major problem, and the production line will have to be overhauled on a large scale.
In the maintenance timing determination system 1 of the embodiment, it is possible to prevent the production line from being stopped and the alarm unit 62 from issuing an alarm just because an oil shortage warning signal 6311 indicating signs of oil shortage is output from the analysis unit 63.
The maintenance timing determination system 1 of the embodiment can also be installed as an addition to the analysis unit 63 of an existing manufacturing line.

(Summary of the maintenance timing determination system)
The maintenance time determination system 1 is composed of (1) an occurrence number detection unit 2, (2) an occurrence frequency detection unit 3, (3) a discrimination unit 4, and (4) a notification unit 5. The functions of these units will be described in order. Note that (1) to (4) in the present invention may be physical devices or parts, or software modules. They may be mounted on a single device, or may exist as a virtual maintenance time determination system 1 by connecting devices that are distributed over a network. There is no limitation on the form as long as the system has the functions of the maintenance time determination system 1 in the present invention.

(Occurrence Number Detection Unit)
The oil shortage alarm signal 6311 sent from the analysis unit 63 is sent to the occurrence count detection unit 2. When the occurrence count detection unit 2 receives the oil shortage alarm signal 6311, it counts the number of occurrences of the oil shortage alarm signal 6311 detected within a predetermined first unit time t1 and calculates the total number. Fig. 2 is an explanatory diagram of the number of occurrences of the oil shortage alarm signal 6311 in the embodiment, and Fig. 2(A) is a graph of the number of occurrences detected in the first unit time t1 created for the purpose of explanation. The vertical axis indicates the number of occurrences of the oil shortage alarm signal 6311 generated within the first unit time t1, and the horizontal axis indicates time in units of the unit time t1.
The first unit time t1 is appropriately determined according to the object to be measured. For a power transmission system 7 that rotates at a relatively high speed, the first unit time t1 is set to be short, and for a power transmission system 7 that rotates slowly, the first unit time t1 is set to be long.

(Occurrence frequency detection unit)
The alarm signal 631 sent from the analysis unit 63 is sent to the occurrence frequency detection unit 3. In Fig. 1, the oil shortage alarm signal 6311 is shown as being sent directly from the analysis unit 63, but the oil shortage alarm signal 6311 may be sent via the occurrence number detection unit 2, and the oil shortage alarm signal 6311 may be sent to the occurrence frequency detection unit 3 in any manner as long as the occurrence frequency detection unit 3 functions as a result.

Fig. 2B is a graph of the number of occurrences detected in the second unit time t2, created for the purpose of explanation. The vertical axis represents the number of occurrences of the oil shortage warning signal 6311, and the horizontal axis represents time in units of the second unit time t2, which is obtained by dividing the first unit time t1 into smaller unit times. In Fig. 2B, the second unit time t2 is obtained by dividing the first unit time t1 into 18 parts.
The second unit time t2 can be set in any suitable manner. The occurrence frequency detection unit 3 counts the number of occurrences of the oil shortage warning signal 6311 received within the second unit time t2.

(Discrimination unit)
As shown in FIG. 1, the discrimination unit 4 receives occurrence count information of the oil shortage warning signal 6311 detected within a first unit time t1 sent from the occurrence count detection unit 2, and also receives occurrence count information detected within a second unit time t2 sent from the occurrence frequency detection unit 3.
As shown in Fig. 2A, the discrimination unit 4 judges whether or not the number of occurrences detected within the first unit time t1 is equal to or greater than the first number of occurrences 42, with the first number of occurrences 42 being a threshold value. The case where the number of occurrences detected is equal to or greater than the first number of occurrences 42 is referred to as a "first state 45." In Fig. 2A, the number of occurrences that is equal to the first state 45 is detected twice.
Next, when the first state 45 is detected, the analysis shown in Fig. 2(B) is performed. Whether the first state 45 has been reached is determined at the end of the first unit time t1, so in this embodiment, the analysis shown in Fig. 2(B) begins after the end of the first unit time t1. This is because the maintenance timing determination system 1 does not notify the user that a dangerous state has been reached, but rather determines and notifies the user that it is time for maintenance, and therefore a determination made every first unit time t1 is sufficient.
Of course, nothing prevents moving on to the analysis shown in FIG. 2B when the first condition is detected more than the first occurrence count 42 before the first unit time t1 ends.

The discrimination unit 4 judges whether the number of occurrences of the oil shortage alarm signal 6311 detected within the second unit time t2 is equal to or greater than the second number 43, which is the second state 46. When the discrimination unit 4 judges that the second state 46 has been reached, the discrimination unit 4 outputs the discrimination result 41 to the notification unit 5. The occurrence of many oil shortage alarm signals 6311 exceeding the second number 43 in the short period of the second unit time t2 is likely not a false detection, but rather indicates the need for maintenance. Even if some kind of false detection occurs, it is best for the operator to check the power transmission system 7 to confirm. If there are too many false detections, the operator can take action by increasing the second number 43, for example.

The discrimination unit 4 also judges whether the number of occurrences of the oil shortage warning signal 6311 detected within each of the consecutive second unit times t2 is equal to or greater than the third number 44, resulting in a third state 47. Each of the consecutive second unit times t2 corresponds to adjacent second unit times t2 in the graph of FIG. 2B. FIG. 2B illustrates the third state 47 in which the number of occurrences of the oil shortage warning signal 6311 equal to or greater than the third number 44 is detected within each of the consecutive second unit times t2. In such a case, the discrimination unit 4 outputs a discrimination result 41 to the notification unit 5.
The fact that the third state 47 has been reached in each successive second unit time t2 indicates that there is a high possibility that the oil shortage alarm signal 6311 is being generated constantly, and thus it is necessary to check this for maintenance purposes and not as a false detection.

To summarize the above explanation of the discrimination unit 4, first, the discrimination unit 4 judges whether a first state 45 has occurred in which the number of occurrences of the oil shortage warning signal 6311 detected within a first unit time t1 has become equal to or greater than a first number 42.
Then, only when the first state 45 is reached, the following two decisions are made.
(1) The discrimination unit 4 judges whether or not a second state 46 has occurred in which the number of occurrences of the oil shortage warning signal 6311 detected within the second unit time t2 has become equal to or greater than the second number 43.
(2) Determine whether a third state 47 has occurred in which the number of occurrences of the oil shortage alarm signal 6311 detected within each of consecutive second unit times t2 has reached or exceeded the third number 44.
The determination unit 4 outputs a determination result 41 to the notification unit 5 when the first state 45 occurs and the second state 46 of (1) is reached.
Moreover, the determination unit 4 outputs the determination result 41 to the notification unit 5 when the first state 45 occurs and the third state 47 of (2) is entered.

As described above, the analysis unit 63 is configured to determine that there is a sign of oil shortage when a sound with a frequency or period different from the frequency of the sound emitted during normal operation is generated, but the threshold for generating the oil shortage alarm signal 6311 indicating a sign of oil shortage can be lowered so that the oil shortage alarm signal 6311 is generated frequently. In this way, it is possible to avoid overlooking sounds and vibrations that are signs of oil shortage that are difficult to detect. Even if the oil shortage alarm signal 6311 is frequently output from the analysis unit 63, the determination unit 4 of the maintenance timing determination system 1 separately determines the sign of oil shortage and determines whether the maintenance time has arrived, so that the worker is not bothered by the frequent oil shortage alarm signal 6311. Even if the analysis unit 63 outputs the oil shortage alarm signal 6311 indicating a sign of oil shortage, there is no need to stop the production line via the production line control device 8, and it is also possible to prevent the alarm unit 62 from issuing an oil shortage alarm.

(Notification Department)
The notification unit 5 receives the discrimination result 41 from the discrimination unit 4 and issues a notification. The notification method is arbitrary, and the notification is issued in a manner suitable for the work place, such as by displaying on a display or by an audio message.

As described above, in the embodiment, the occurrence number detection unit 2 and the occurrence frequency detection unit 3 have been described separately. However, the occurrence number detection unit 2 and the occurrence frequency detection unit 3 are the same in that they both count the number of times of the oil shortage warning signal 6311, and the only difference is that the unit time is the first unit time t1 and the second unit time t2. Therefore, the occurrence number detection unit 2 and the occurrence frequency detection unit 3 can be integrated into one unit, which is also included in the present invention.
As mentioned above, the main parts of the occurrence count detection unit 2, occurrence frequency detection unit 3, discrimination unit 4 and notification unit 5 may be software modules, and it goes without saying that a device incorporating software that integrates these parts may be used as the maintenance time determination system 1.

Furthermore, although the embodiment has been described with respect to signs of oil shortage, the present invention can be applied to any sensor or object to be detected, including sensors that are prone to false detection.
As shown in the examples, a new maintenance timing determination system can be provided.

The maintenance timing determination system 1 of the present invention can also be installed in various devices such as manufacturing lines.

Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.
Furthermore, the above-described embodiments and modifications can be combined by utilizing each other's technologies, so long as there are no particular contradictions or problems in the purpose, configuration, and the like.

1 Maintenance timing determination system 2 Occurrence number detection unit 3 Occurrence frequency detection unit 4 Discrimination unit 41 Discrimination result 42 First number of times 43 Second number of times 44 Third number of times 45 First state 46 Second state 47 Third state 5 Notification unit 6 Sound/vibration sensor (abnormality detection sensor)
61: Sound and vibration data 62: Alarm unit 63: Analysis unit 631: Alarm signal 6311: Oil shortage alarm signal 7: Power transmission system 71: Gear 8: Production line control device 81: Restart button t1: First unit time t2: Second unit time

Claims (1)

An occurrence number detection unit, an occurrence frequency detection unit, and a discrimination unit are provided,
The occurrence number detection unit counts the number of occurrences of an alarm signal detected by the abnormality detection sensor within a predetermined first unit time,
the occurrence frequency detection unit counts the number of occurrences of the alarm signal detected within a second unit time obtained by dividing the first unit time into a smaller unit time,
The discrimination unit is
A first state occurs in which the number of occurrences of the alarm signal detected within a first unit time is equal to or greater than a first number, and
(1) a second state in which the number of occurrences of the alarm signal detected within a second unit time is equal to or greater than a second number;
or
(2) A maintenance time determination system characterized by outputting a maintenance time determination result when a third state occurs in which the number of occurrences of the alarm signal detected within each of consecutive second unit times is equal to or greater than a third number.

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