JPH0399252A - Method and apparatus for estimating and displaying remaining life of member - Google Patents

Abstract

PURPOSE:To achieve higher reliability and safety by measuring limit damage length and actual length of a flaw. CONSTITUTION:Degree of damage is detected as length (a) of a flaw with a detector 5. The length ai of a damage is estimated at the subsequent operation, for example, after 6 months from the length (a) detected. The subsequent formula is determined from a detection or calculation value of the length of the flaw at present. log (a)=C(t/ tr), wherein C represents constant determined by grain size, tr breaking life, (t) elapsed time for member under a high temperature. On the other hand, a hysteresis loop area A is detected with an aging detector 10 to calculate a limit damage length acr for the member from the area A. A forecast limit damage length acri after 6 months is forecast by estimating a progress of the limit damage length acr. The lengths ai and acri are compared and when the estimated damage length ai does not reach the forecast limit damage length acri, after the estimating period, the life of the member does not yet expire even after the 6 months. Hence, the extra life of the member is diagnosed. In the diagnosis of the residual life, the life is determined as time until it reaches intersection between extension of the estimated damage length ai and extension of the forecast limit damage value acri as 100% of life.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to the remaining life diagnosis of components used in environments that degrade materials, such as high temperature environments and high radiation environments, and particularly relates to the remaining life diagnosis of components. The present invention relates to a remaining life diagnosing method and a diagnostic device suitable for accurately, reliably and quickly diagnosing even an unskilled person, and a display method and a display device for displaying the diagnosis results.

[Background Art] When operating a thermal power plant, a nuclear power plant, etc., it is necessary to ensure operational safety and stable supply of electric power. Therefore, it is necessary to maintain each part in the best condition so that the various parts constituting the plant will not be damaged and malfunction, causing the plant to be shut down for a long period of time. On the other hand, replacing parts with new ones even though their lifespan has not yet expired is not only costly and wasteful, but also impedes the smooth operation of the plant, given the high initial failure rate. It becomes a factor. Therefore, it is preferable to diagnose the remaining life of each component and replace the components starting with those that are most likely to cause damage, in terms of cost, plant operation efficiency, and safety.

In the conventional remaining life diagnosis, for example,
As described in Publication No. 7, the temperature and stress are calculated from the usage state quantities of the high-temperature member, and the high-temperature The amount of damage sustained by the component is calculated, and the remaining life is estimated from this calculated value.

In the remaining life diagnosis that is actually performed, the remaining life of the component is estimated by evaluating the results of non-destructive tests covering a plurality of items, similar to the above-mentioned conventional technology.

[Problem to be solved by the invention] Conventional remaining life diagnosis technology estimates remaining life using non-destructive test results covering multiple items, but accurate estimation requires advanced knowledge and wealth. There is a problem in that non-experts cannot diagnose the remaining lifespan because it requires experience. This is because in the past, various non-destructive test results were obtained blindly, and the causal relationship was determined based on experience without quantifying their mutual relationship (causal relationship).

A first object of the present invention is to provide a method and apparatus for diagnosing the remaining life of a (high temperature) member that can accurately diagnose the remaining life.

A second object of the present invention is to provide a display method and display device that allow even an unskilled person to easily and quickly determine the remaining life.

[Means for Solving the Problem] The first objective is to detect the physical quantity of a member and determine the current critical damage length acr (this length is the length that the flaw has reached). This is the value indicating that the member will be damaged when the material is damaged. Therefore, this length will become shorter as the material deteriorates. This is achieved by diagnosing the remaining life of the member from the length a of the scratch.

The first purpose is to detect the physical quantities of the member to determine the progression prediction line of the critical damage length acr of the member, and to detect the growth of the flaw from the detected value a of the actual length of the flaw on the surface or inside of the member. This is achieved by finding a predicted line and diagnosing the remaining life using the intersection of the face measurement lines as the life limit value.

The second objective is achieved by displaying the critical damage length acr and the actually detected length a of the flaw together with past data on a graph screen that shares a common time axis.

The second purpose is to display the progress prediction line and the growth prediction line on a graph screen with a common time axis.
achieved.

[Operation] When the scratches that grow inside or on the surface of a member reach a certain length, the member becomes unusable due to the scratches, and the life of the member comes to an end. Therefore, by predicting the growth of scratches, the remaining life of the component can be diagnosed.

However, it is not possible to make an accurate diagnosis just by predicting the length of the wound. In other words, if the material of the component does not undergo any deterioration,
It is possible to fully diagnose the remaining life just by predicting the length of the scratch, but as the material itself deteriorates, the length of the scratch becomes shorter than predicted and the component becomes unusable. In other words, the critical damage length of a member becomes shorter depending on the degree of deterioration of the material. Therefore, in the present invention, diagnosis is performed taking into consideration both the degree of deterioration of the material and the length of the flaw, so it is possible to accurately diagnose the remaining life.

In addition, when displaying the diagnosis results from the remaining life diagnosis device, by displaying the limit damage length and the length of the actually detected scratches on the screen using a common time axis, it is possible to visually determine the progress of deterioration and the extent of scratches. Growth can be seen and even non-experts can easily judge.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a remaining life diagnosis device in an embodiment of the present invention. The remaining life diagnosis device in this embodiment LQ is a damage level detection system 1 that detects scratches on the surface of a member.
, a deterioration degree detection system 2 that detects the degree of deterioration of the component, a remaining life diagnostic device 3 that diagnoses the remaining life from the correlation between the detected values of both systems 1.2, and a diagnostic result of the remaining life diagnostic device 3. It consists of a display device 4 for displaying images.

As a damage level detection system 1 In this embodiment, flaws on the surface of a member are directly detected as described later, but the present invention is not limited to this, and for example, flaws inside the member may be detected using an ultrasonic flaw detector. It goes without saying that anything you do is fine. In addition, in this embodiment, as the deterioration degree detection system 2,
Although the magnetic properties of the member are detected, the present invention is not limited to this, and any physical quantity that changes as the member deteriorates, such as the electrical resistance or hardness of the member, may be detected. Furthermore.

In this example, the remaining life of a member due to heat is diagnosed.
It is not limited to thermal fatigue, but can also be applied to remaining life diagnosis of components that are damaged or deteriorated by exposure to radiation such as neutron beams, or components that are damaged or deteriorated by repeated operation cycles. Of course.

The damage level detection system 1 according to the present embodiment includes a surface microscopic damage detector 5 that is an optical damage detector, and an imaging control device 6 that adjusts the magnification, focus, etc. of the damage image taken by the detector 5.
, a position control device 7 that controls the position of the detector 5 so as to be at the position of the flaw on the surface of the member to be detected, and an image processing device 8 that processes and digitizes the damage image to detect the length of the damage. and a damage degree calculation device 9 that performs statistical processing on the length of each detected flaw to calculate the degree of damage to the member.

In fact, when detecting the degree of damage to a member, the problem is whether the detector 5 can accurately detect damage with a size of 1 mm or less. The main form of damage is micro defects such as non-metallic inclusions contained in metal materials, and cracks that occur from corrosion holes (cracks that occur early in life), which are several tens of microns deep.
It is on the order of m (same size as a crystal grain), and this is a problem in the microscopic region. There is a unique relationship between the growth of microscopic damage and the life of the member, regardless of the load applied to the member or the material, as described in, for example, Japanese Unexamined Patent Publication No. 61-139743. Therefore, it is important to accurately detect the length of damage from the time of microscopic damage. However, in the past, such microscopic damage was not considered much of a problem, and for this reason, highly accurate detectors were not used. However, in the present invention, since microscopic damage becomes a problem, a highly accurate detector 5 is used.

FIG. 2 is a detailed configuration diagram of the surface microscopic damage detector 5. As shown in FIG.

This detector 5 is connected to an object to be observed (member to be diagnosed with remaining life) 20
a prism 21 that captures an image of the surface of
3, a photoelectric conversion device (TV camera) 24 made of a solid-state imaging device such as a COD that converts images obtained by these optical systems into electrical signals, a servo motor 26 that adjusts the imaging of the zoom lens, and a photoelectric conversion device It consists of a cable 25 that connects I24 and the imaging control device 6 shown in FIG. Note that the servo motor 26 is connected to the imaging control device 6 via the cable 25.
It is controlled by control signals sent from. Such a configuration makes it possible to magnify and detect even minute damage of several tens of micrometers.

The deterioration degree detection system 2 shown in FIG. Judging from the area of the hysteresis loop. Therefore, the deterioration detection system 2 in this embodiment includes a magnetic deterioration detection device 10 (details of which will be described later), a magnetization control device 11 that controls excitation and magnetic detection of the detection device 10, and a position that controls the inspection target position. It consists of a control device 12, a data processing device 13 that processes detection data from the detection device 10 as deterioration parameters, and a deterioration degree calculation device 14 that evaluates the data-processed deterioration parameters based on data stored in a database of the member and material.

FIG. 3 is a detailed configuration diagram of the magnetic deterioration detection device 10.

This detection device includes a waveform controlled oscillator 31 whose waveform is controlled in response to a control signal from the magnetization control device 11, an amplifier 32 that amplifies one oscillation output, and is excited by the flow of the current output from the amplifier 32. It consists of an excitation coil 33, a magnetic sensor 34 provided between the excitation coil 33 and the member to be measured 20, and a converter 35 that converts the output of the sensor 34.

Next, the principle of diagnosis by the remaining life diagnosis apparatus having the above-described configuration will be explained.

It is known that low-alloy steel used in many high-temperature devices becomes brittle when used at high temperatures for long periods of time.

Therefore, the characteristics graph shown in FIG. 4 is the result of exposing the material to high temperatures for a long time and examining the changes in its magnetic properties. In this graph, the horizontal axis is the parameter P of temperature T and time t,
The vertical axis is the area A of the magnetic hysteresis loop as the magnetization characteristic. When the detected hysteresis loop area A is plotted against the parameter P, it can be seen that the relationship shown in FIG. 4 exists. In other words, it can be seen that the hysteresis loop area A is a function of the parameter P, that is, the temperature T and the time t.

\ On the other hand, it has been found through experiments that there is a correlation between the Charpy impact value (CVN), which quantitatively indicates the embrittlement (deterioration) of a material, and the magnetization hysteresis loop area A, as shown in Figure 5. There is. In other words, when a component is exposed to high temperature, the hysteresis loop area A changes depending on the temperature T and the time t it is exposed to high temperature, and this area A has a correlation with the Charpy impact value, so the hysteresis loop The degree of deterioration of the member can be evaluated from the area A.

In the present invention, the remaining life of the member is diagnosed based on both the degree of deterioration and the degree of damage. Therefore, next, the degree of damage detected non-destructively (in this example, the length a of the scratch on the member surface) and the degree of deterioration detected non-destructively (in this example, the magnetization hysteresis loop area a) are This section explains the principle of using this method to diagnose remaining life.

FIG. 7 is a flowchart showing the remaining life diagnosis procedure executed by the remaining life diagnosis device shown in FIG.

First, the degree of damage is detected by the detector 5. In this embodiment, the length a of the scratch is detected. Furthermore, this length a is.

The detected length a may be left as it is, or
This length a may be corrected as in the technique described in Japanese Patent No. 139743. In this embodiment, the lengths of a large number of scratches are detected and a representative length a is calculated through statistical processing (step 1). Next, in step 2,
From the calculated length a, estimate the damage length ai next time, for example, after 6 months. For example, if it is estimated that it will grow by Δa, set ai=a + Δ a. The estimation of Δa is, for example, the previous damage length ai. Although it may be estimated from the difference from the detected/calculated length a, in this embodiment, it is determined directly from the detected value or calculated value of the current flaw length using the following equation.

1og a=C(t/l r) Here, C is a constant that can be determined experimentally or based on the grain size, and its value is, for example, ro
, about 2J. tr is the rupture life, and this value is unknown. However, since the relationship between a and the ratio (t/lr) to the elapsed time t of the member under high temperature is known, the extent of damage growth can be determined from this equation.

On the other hand, the deterioration detection device 1o detects the hysteresis loop area A, and calculates the critical damage length acr in the member from this area A (step 3).

The principle of this calculation will be explained. The critical damage length acr is related to the toughness of the member. Therefore, the critical damage length acr is the fracture toughness value KI that indicates the fracture resistance of the member.
It can be determined from C using the following equation.

KIC=f・σ・l]=7ττcf: Shape parameter of the member σ: Stress Also, since this fracture toughness value KIC has the following relationship with the Charpy impact value CVN mentioned above, the Charpy impact value C
It can be obtained from vN.

(KIC/a ys)” = 5 ((CVN/a
ys) -0,05) σys: Yield point of material Meanwhile, as described above, the Charpy impact value CVN and the hysteresis loop area A have the relationship shown in FIG. In other words, the relationship is 1ogCVN=A. Therefore, the critical damage length acr can be determined from the hysteresis loop area A.

In the next step 4, the progression of this critical damage length acr is predicted, and the predicted critical damage length a cr after 6 months, for example, is calculated.
Predict i. This prediction, that is, the rate at which the predicted critical damage length will decrease, Δa', is predicted and determined as acri=acr-Δa'. Δa′ may be calculated from the currently determined critical damage length and the previously determined critical predicted length, but in this example, Δa′ is determined from only the currently determined critical damage length.
Predict the exact acri. The critical damage length acr is
As mentioned above, the critical damage length acr is found from the hysteresis loop area A, which has a correlation with the Charpy impact value CVN, and since this area A is a function of the parameter P (a function of temperature T and time t), the critical damage length acr is determined by the Charpy impact value CVN. It is a function of the impact value and the parameter P. Therefore, the critical damage length ac
The critical damage prediction length acri is determined from r.

In the next step 5, the length ai obtained in step 2 and
Compare the length acri obtained in step 4,
If the predicted damage length ai has not reached the limit predicted damage length aeri, the remaining life of the component is diagnosed because the life is still not over after the prediction period, that is, after 6 months in the above example. (Step 6), return to Steps 1 and 3. As will be described in detail later, the diagnosis of the remaining life is determined as the time required to reach 100% life, which is the intersection of the extension line of the predicted damage length ai and the extension line of the critical damage prediction value acri.

If it is determined in step 5 that the predicted damage length ai is equal to or greater than the critical predicted damage length acri, the member will necessarily reach the end of its life after the prediction period, so in step 7 the member is repaired or replaced.

In the remaining life diagnosis in step 6 of FIG. 7, in this embodiment, the graph shown in FIG. 6 is displayed on the display device,
To enable even an unskilled person to easily and quickly diagnose remaining life.

As shown in FIG. 6, the remaining life diagnostic device 3 stores past detection and calculation data, and plots the currently detected or calculated damage length ai and limit damage length aer on the screen. At this time, set the horizontal axis of the screen to be common (for example, t/l
Let it be r. ) so that the growth of the damage length a and the tendency for the critical damage length to become shorter can be seen at a glance. Thereby, even an unskilled person can easily grasp the deterioration tendency of the member, the degree of flaw growth, and the correlation between the two.

In addition, on this display screen, the extension line of each plot point (
For example, by calculating and displaying the predicted line (predicted line) using the least squares method, the trend becomes clearer.Furthermore, in order to understand the degree of change between the past predicted line and the current predicted line, The predicted line may be displayed in different colors from the past predicted line.In this embodiment, the predicted line is not determined by the least squares method, but is determined from only the current detected value, so this predicted line is also used. By displaying the color components at the same time as the predicted line obtained using the least squares method, it is possible to improve the diagnostic accuracy.

Note that the remaining life of a member usually varies depending on the location if the shape, position, etc. of the member differ. Therefore, the entire part is displayed on the display device, and the remaining life of each part is displayed in shading or color on this display screen to indicate which part has a short remaining life and which part has a long remaining life. If you make it easy to understand, the trends will become obvious at a glance.

The above is a description of the remaining life diagnosis device in this embodiment. FIG. 8 shows an example of a detection device that can suitably detect the magnetic characteristics of a member in this embodiment.

This detection device uses a superconducting quantum interference device (SQUID) as a magnetic sensor. In Figure 8, 81 is 5
It is QUID. In this detection device, an excitation coil 8 made of a superconducting material is placed inside a container 87 made of a non-magnetic material.
3 and a coolant 88 such as liquid helium, a current is passed through the excitation coil 83, and the member to be measured 20 is excited by the generated strong magnetic field. Then, the excitation coil 38 is covered with a magnetic shield 84 other than the surface facing the object to be measured, and the detection signal of the pickup coil 82 placed in the center of the excitation coil is guided to the 5QUID 81 placed outside the magnetic shield 84, and the detection signal 89 of the 5QUID 81 is is sent to the data processing device via the magnetization control device. Note that 86 is a cooling device for the coolant 88, and 85 is a pipe, through which the coolant 88 is recirculated and cooled.

By using a configuration using such a superconducting quantum interference element, magnetic field detection can be made highly sensitive, and the accuracy of detecting material deterioration can be dramatically improved.

Using a laser microscope or an ultrasonic microscope as an optical surface microscopic damage detector further improves the accuracy of surface damage detection.

[Effects of the Invention] According to the present invention, even an unskilled person can easily and quickly diagnose the accurate remaining life of a member, thereby improving the reliability and safety of a device that uses the member. This also makes maintenance management easier.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a remaining life diagnosis device according to an embodiment of the present invention, FIG. 2 is a detailed block diagram of the surface microscopic damage detector shown in FIG. 1, and FIG. A detailed configuration diagram of the deterioration detection device, and FIG. 4 is a graph showing the relationship between the magnetic hysteresis loop area and the parameter P (a function of temperature T and time t).
FIG. 5 is a graph showing the relationship between Charpy impact value and magnetic hysteresis loop area, FIG. 6 is an explanatory diagram showing an example of a display screen of a display device according to an embodiment of the present invention, and FIG.
A flowchart showing the diagnostic procedure executed by the remaining life diagnostic device shown in the figure, and FIG. 8 is an explanatory diagram of another embodiment of the magnetic deterioration detection device. DESCRIPTION OF SYMBOLS 1... Damage degree detection system, 2... Deterioration degree detection system, 3... Remaining life diagnostic device, 4... Display device, 20
...Parts to be diagnosed.

Claims (1)

[Claims] 1. In a method for diagnosing the remaining life of a member exposed to high temperatures, the length a of a flaw that grows on the surface or inside of the member due to thermal fatigue is measured, and the length a of the damage caused by thermal aging is determined. A method for diagnosing the remaining life of the member, comprising: measuring a physical quantity, determining a critical damage length acr from the measured value, and diagnosing the remaining life of the member from both lengths a and acr. 2. In a method for diagnosing the remaining life of a component used in a high-temperature environment, the length a of a flaw that grows on the surface or inside of the component due to heat is measured, and a growth prediction line of the length a is determined. and measure the physical quantity of the member that deteriorates due to heat,
A fracture toughness value indicating the fracture resistance of the member is determined from the measured value, a critical damage length acr is determined from the fracture toughness value, a predicted line of the critical damage length acr is determined, and the predicted line and the growth predicted line are determined. A method for diagnosing the remaining life of the member, with the intersection of the two being 100% of the life. 3. In claim 2, the growth prediction line has a material constant of C,
The elapsed time is t, the rupture life is tr, and t/tr=log
A method for diagnosing remaining life, characterized in that the material constant C is determined from the grain size of the member or an experimental value. 4. In a method for diagnosing the remaining life of a member used in an environment that deteriorates the material, the length of the scratch on the surface or inside of the member that grows over time is detected, and the physical quantity of the member that deteriorates over time is determined. A method for diagnosing remaining life of the member, comprising measuring the length of the flaw detected by the detection and the value of the physical quantity obtained by the measurement. 5. In a method for diagnosing the remaining life of a component used in an environment that degrades the material, the length of the scratch on the surface or inside of the component that grows over time is detected, and the physical quantity of the component that deteriorates over time is determined. is measured, a critical damage length is calculated from the measured value, a flaw growth prediction line is determined from the detected flaw length, and a progression prediction line of the critical damage length is determined from the calculated critical damage length. , and the remaining life of the member is determined by using the intersection of the predicted growth line and the predicted progress line as the life limit point. 6. A remaining life diagnosis device for diagnosing the remaining life of a component used in a high-temperature environment, including a non-destructive damage detection means for measuring the length of a flaw that grows on the surface or inside of the component in response to heat; The remaining life of a high-temperature member is characterized by comprising: a non-destructive deterioration detection means for measuring a physical quantity of the member that deteriorates due to the heat applied thereto; and a calculation means for calculating the remaining life of the member from the detected values of both the detection means. Lifespan diagnosis device. 7. A remaining life diagnosis device for diagnosing the remaining life of a component used in a high-temperature environment, including a non-destructive damage detection means for measuring the length of a flaw that grows on the surface or inside of the component in response to heat; non-destructive deterioration detection means for measuring the physical quantity of the member that deteriorates due to the damage; Calculate the progression prediction line of the critical damage length, and set the intersection of the progression prediction line and the growth prediction line to 100% of the lifespan.
and a calculation means for calculating the remaining life of the member. 8. In claim 7, the calculation means uses the detected flaw length a, the growth prediction line, the material constant C, and the elapsed time t.
, where tr is the rupture life, calculated as t/tr=loga/C, and the material constant C is determined from the grain size of the member or an experimental value. 9. In claim 7 or claim 8, the non-destructive deterioration detection means is one that measures the area of the magnetic hysteresis loop of the member, and the calculation means calculates the Charpy impact from the value of the area which is a function of temperature and time. determine the fracture toughness value of the member from the Charpy impact value, determine the critical damage length at the time of measurement of the member from this fracture toughness value,
A remaining life diagnosing device characterized in that the progression prediction line is calculated from this critical damage length. 10. In claim 7 or 8, the non-destructive deterioration detection means is one that measures the area of the magnetic hysteresis loop of the member, and the calculation means calculates the Charpy impact from the value of the area which is a function of temperature and time. Determine the fracture toughness value of the member from the Charpy impact value, determine the critical damage length at the time of measurement of the member from this fracture toughness value, and compare the determined critical damage length with the previously determined critical damage length. A remaining lifespan diagnosis device, characterized in that the progression prediction line is calculated from. 11. In claim 9 or 10, when the calculation means calculates the fracture toughness value KIC from the Charpy impact value CVN, the yield point of the material is σys, and (KIC/σys
) ^2 = 5 ((CVN/σys) - 0.05), and when determining the critical damage length acr from the fracture toughness value KIC, the shape parameter of the member is f, the stress is σ, and KIC = f・σ - A remaining life diagnostic device characterized by calculating from the relationship of √(π・acr). 12. In an apparatus for diagnosing the remaining life of a member used in an environment that deteriorates the material, a means for non-destructively detecting the length of a scratch on the surface or inside of the member that grows over time, and a means for detecting the length of a scratch on the member's surface or inside that grows over time; a means for non-destructively measuring the physical quantity of the member in which the damage progresses; and a means for calculating the critical damage length from the measured value, calculating a flaw growth prediction line from the detected flaw length, and determining the limit from the calculated critical damage length. 1. A remaining lifespan diagnosing device, comprising: calculating means for determining a progression prediction line of damage length and calculating the remaining life of the member by using the intersection of the growth prediction line and the progression prediction line as the limit point of lifespan. 13. In an apparatus for diagnosing the remaining life of a member used in an environment that degrades materials, a means for non-destructively detecting the length of scratches on the surface or inside of the member that grows over time, and and a calculation means for calculating the remaining life of the member from the length of the flaw detected by the detection and the value of the physical quantity determined by the measurement. Lifespan diagnosis device. 14. In the remaining life display method for displaying the diagnosis result by the remaining life diagnosis device according to any one of claims 6 to 13, the detected value of the length of the scratch on the surface or inside the member and the measured value of the measured physical quantity. A method for displaying remaining life, characterized by displaying the data together with past data on a graph screen with a common time axis. 15. In the remaining lifespan display method for displaying the diagnosis result by the remaining lifespan diagnosis device according to any one of claims 7 to 12, the obtained growth prediction line and progression prediction line are displayed on a graph screen with a common time axis. A method for displaying remaining life, characterized by displaying the remaining life on the top. 16. The method for displaying remaining life according to claim 15, characterized in that a predicted growth line and a predicted progression line based on past data are also displayed. 17. In the remaining life display device that displays the diagnosis result by the remaining life diagnosis device according to any one of claims 6 to 13, a detected value of the length of a scratch on the surface or inside of the member and a measured value of the measured physical quantity. A remaining life display device characterized by displaying the information on a graph screen having a common time axis together with past data. 18. In the remaining lifespan display device for displaying the diagnosis result by the remaining lifespan diagnosis device according to any one of claims 7 to 12, a graph screen is provided in which the obtained growth prediction line and progression prediction line are displayed on a common time axis. A remaining life display device characterized by displaying the remaining life on the top. 19. The remaining life display device according to claim 18, characterized in that a growth prediction line and a progress prediction line based on past data are also displayed.