KR20010061642A - Apparatus for diagnosing mill by spindle torque - Google Patents

Abstract

PURPOSE: A mill examiner is provided to guide a shape of a load and defects of a rotator by monitoring a rolling motor and a spindle torque of a mill and to prevent a breakage of a spindle. CONSTITUTION: A mill examiner comprises: a strain gauge(1) to detect twisting stress to be added into a rotating spindle; a transmitter(2) to transmit the detected signal from a rotating member to a fixing member; transmitting/receiving antennas(3) to transmit and to receive the signals by installing in the rotating member and the fixing member; a receiver(4) to reproduce the transmitted signal; a data collector(5) to collect data by receiving from the receiver and to offer the data into an output device by automatically backing up; and the output device(6) to display a theoretical torque and a spindle torque on a monitor based on the data and to display a torque distribution chart, a TAF(Terminal Adaptation Functions) distribution chart and a life prediction charge for predicting a state of equipments. Thereby, the twisting stress is monitored always.

Description

Diagnosis device for rolling mill by shaft torque {APPARATUS FOR DIAGNOSING MILL BY SPINDLE TORQUE}

The present invention relates to a rolling mill equipment, and more specifically, to monitor the control signal and electrical torque for the speed control of the motor and mechanical shaft torque of the spindle (Spindle) at all times to provide the failure information in the event of a problem in the equipment to find out the cause of the error The present invention relates to a rolling machine diagnosis device based on shaft torque for preventing the breakage of the spindle in advance by predicting the stable operation of the equipment through the distribution and trend analysis of the shaft torque and the cumulative management of the fatigue stress.

In general, a motor is widely used in the rolling equipment for precise control, and in the related art, it is difficult to measure the shaft torque of the motor in the rolling equipment, and thus the shaft torque is indirectly determined by the electrical torque of the motor. Actual shaft torque was not obtained correctly.

In addition, the measurement of the motor torque was calculated by manual measurement after measuring the voltage, current, and rotation speed by a measuring instrument or a recorder, and the theoretical torque of the motor was calculated and read.

In particular, when the shaft torque measurement is necessary, the portable torque measuring machine was installed to read the shaft torque. However, this measurement method is limited to the short-term measurement because it cannot be continuously measured for a long time. It was difficult to accurately analyze the torque.

In addition, the stress received by the rolling mill depends largely on the operation pattern such as the rolling load and the stability of the control system.To date, excessive stress on the rolling mill due to severe operation for increasing production, instability of the electric control system, and driving error causes the motor trip ( Motor trip) and spindle loss were occurred, but even when a problem occurred, it was difficult to grasp the phenomenon before and after the occurrence and it was impossible to grasp mechanical stress.

The present invention has been made to solve the above-described problems, the object of which is to measure the torsional stress on the rotating shaft, and transmits this signal to the fixed side by the FM (frequency modulation) radio method, the shaft torque value again It is to provide a rolling mill diagnostic device by the shaft torque to be constantly monitored in the output device in terms of.

1 is a block diagram showing the overall configuration of a rolling mill diagnostic apparatus according to the shaft torque according to the present invention.

Figure 2 is a schematic diagram showing the installation configuration of the torque measuring unit in the diagnostic apparatus according to the present invention.

3 is a torque signal flow diagram illustrating a process of measuring and transmitting a torque signal in a diagnostic apparatus according to the present invention.

Figure 4 is a block diagram showing the configuration of the data collection control unit in the diagnostic apparatus according to the present invention.

FIG. 5 is a flowchart for explaining a data collection and processing method performed in a data collection apparatus. FIG. 5A is a processing diagram for failure analysis and real-time trend analysis, and FIG. 5B is a history data processing diagram.

FIG. 6 is a flowchart for explaining the torque data collection processing and diagnostic algorithm. FIG. 6A is a torque data processing method diagram, and FIG. 6B shows a torque diagnosis algorithm.

FIG. 7A is a torque distribution data table, FIG. 7B is a TAF management data table, and FIG. 7C is a table comparing effects of output screens for respective functions.

8 is an S-N curve diagram of material SF60 of a spindle;

* Description of the symbols for the main parts of the drawings *

1 ... Strain Gauge 2 ... Transmitter

3. Transmitter and receiver antenna 4 ... Receiver

5 ... Data acquisition device 5a ... Analog signal input

5b ... Digital signal input 5c ... Multiplexer

5d ... A / D converter 5e ... 1st memory (for collecting 0.1msec data)

5f ... 2nd memory (for 1msec data collection)

5g ... 3rd memory device (20msec data collection)

5h ... control unit 5i ... 4th memory device (for historical data)

6.Output device 101 ... Motor shaft

102 ... Spindle 103 ... Stand

104 ... Work Roll

As a constitutional means for achieving the above object of the present invention, the rolling mill diagnostic apparatus according to the shaft torque of the present invention

A strain gauge for detecting the torsion stress applied to the rotating shaft,

A transmitter for transmitting the signal detected by the strain gauge from the rotor to the fixed side;

A transmission / reception antenna installed at the rotating body and the fixed side to transmit and receive signals,

A receiver that receives and reproduces a transmission signal,

A data collecting device which receives each data inputted from the receiver and collects data in real time, and automatically backs up the data within a predetermined range before and after the occurrence of an event or an alarm and provides the output device as required;

Output device that displays the theoretical torque and shaft torque based on the data sent from the data collection device and displays them on the screen, and displays the torque distribution chart, TAF distribution chart and life prediction chart on the screen so that the user can predict the equipment condition. Characterized in that consists of.

Briefly describing the present invention, first, in order to calculate the measurement stress range of the rotating shaft, considering the output torque of the motor, the allowable strength of the shaft, and the like, the measurement range of the strain gauge 1 as shown in Equation 1 of the following torque and stress Determine appropriately.

In the above, T is the torque, G is the lateral elastic modulus [N mm 2], D is the shaft diameter [mm 2], and ε is the stress.

In order to stably transmit the stress signal measured from the rotating shaft to the fixed side, the technical specifications of the transmitter 2, the transmission / reception antenna 3, the receiver 4, etc. are selected to suit the site conditions.

In this case, the transmit / receive frequency should be selected so as not to influence or be affected by the surrounding wireless devices, and the transmission frequency for each transmitter is different. Also, the important factor is that the signal and the signal having the same characteristics as the original signal during the signal transmission process. The size must also be guaranteed to be linear, and the calibration must be done accurately to ensure this.

The torque data obtained from the field must be collected in synchronization with the electric control data, so that a data traceback up of 0.1 msec / 1 msec / 20 msec period and a data collection device capable of data collection of 20 msec period ( 5) was used.

In addition, the torque distribution chart is used to determine the load rating and overload condition acting on the spindle, the TAF distribution chart is used to determine the play and impact of the rotation system, and the diagnosis of predicting the remaining service life and life by cumulative working fatigue stress. Implement the algorithm.

Now, with reference to the accompanying drawings will be described in detail the configuration and operation of the diagnostic apparatus according to the present invention.

1 is a block diagram showing the overall configuration of a diagnostic apparatus according to the present invention, a strain gauge 1 for detecting a torsional stress applied to a rotating shaft, and a transmitter 2 for transmitting this signal from a rotating body to a fixed side. ), A transmitting / receiving antenna (3) installed on the rotating body and the fixed side, respectively, to receive and transmit a signal, a receiver (4) for receiving and reproducing a transmission signal, and receiving each data input from the receiver (4). A data collecting device 5 which collects data in real time and automatically backs up data within a predetermined range before and after an occurrence of an event or alarm and provides the output device 6 as required; and the data collecting device 5 as a user interface device. The theoretical torque and shaft torque are calculated and displayed on the screen based on the data sent from the system. It consists of an output device 6 which displays the prediction degree on the screen.

In addition, as shown in FIG. 4, the data collecting device described above includes a torque signal, a motor voltage, a current, a rotation speed, a rolling reduction amount, an operation on-off signal, a light fault, and a heavy fault ( Various signals required for diagnosis such as Heavy Fault) and the analog signal input terminal 5a and the digital signal input terminal 5b to which these signals are input, and the signals input from the analog signal input terminal 5a and the digital signal input terminal 5b. Selected sequentially, the analog signal is applied to the A / D converter 5d and the digital signal is applied to the multiplexer 5c to the first to third storage devices 5e to 5g, and the input signal is connected to the high speed A /. A first D / D converter 5d for converting D, and each data input from the A / D converter 5d and the multiplexer 5c are stored at set cycles, respectively, and a first range for backing up and outputting a range of data as required. To fourth memory devices 5e to 5g, 5i and the alarm occurrence and / or Therefore, the event occurrence, or a user's request of the first to fourth memory device to output the data stored in the (5e-5g, 5i) is composed of a control arithmetic unit (5h) for transmitting to the output device (6).

The output device 6 for query analysis of data in FIG. 1 is composed of a computer and a printer. The device is equipped with a monitoring screen for requesting and outputting various data, and for diagnosis of rolling mills and spindles. The software of the torque diagnosis algorithm (FIGS. 5 and 6) is mounted.

Hereinafter, the operation according to the present invention will be described with reference to the accompanying drawings.

As shown in Figs. 2 and 3, the strain gauge 1 installed in the motor shaft measures the torsional stress proportional to the torque. The measured stress value is the same as that of Equation 1 described above.

As described above, the fine signal detected by the strain gauge 1 is amplified by the amplifier 2a of the transmitter 2, and is modulated at a frequency proportional to the voltage by the V / F converter 2b to transmit / receive an antenna 3 as a transmission means. Is transmitted over the air to the receiver.

The receiver 4 on the receiving side amplifies the signal transmitted as described above in the amplifier 4a to a predetermined level, converts the signal back to the voltage in the F / V converter 4b, and reproduces the original stress signal.

As described above, the signal reproduced with the original signal is input to the analog signal input terminal 5a of the data collecting device 5.

As described above, the processing in the data collecting device 5 for the collected data will be described, which refers to the flowcharts of FIGS. 4 and 5 to perform the step-by-step operations from the input stage to the storage device and the control operation section. Explain.

The analog signal input terminal 5a of the data collecting device 5 inputs torques measured as described above, electrical signals of the rolling motor, that is, signals of voltage, current, rotational speed, rolling mill rolling amount, and the digital signal input terminal. (5b) inputs a condition signal such as on / off signal, light fault, heavy fault, and the like and has a high input impedance such that the signal is stably input.

As described above, the multi-channel analog signal and the digital signal input to the input terminal are sequentially selected by one channel at a moment instantaneously in the multiplexer 5c, and the analog signal is the A / D converter 5d, and the digital signal is the first to the first. It is transferred to three memory devices (5e ~ 5g).

The analog signal input to the A / D converter 5d is digitalized and coded into data that can be recognized by a computer. As described above, the A / D-converted analog data and the digital data selected by the multiplexer 5c are basically processed at 0.1 msec periods, and each memory device is a 0.1 msec period data storage device 5e and 1 msec share price data. The memory device 5f, the 20msec data storage device 5g, and the history data storage device 5i are controlled and stored in the respective periods to store data.

The data processing and utilization of each memory device is described below.

The first memory device 5e stores data while continuously shifting data collected at 0.1 msec periods as shown by 'a' in FIG. 5a (s510, s511), and at 20msec period data. If an alarm occurs (greater than the threshold) and an event (heavy fault) occurs or a user request signal is present (s512), the data of 4 seconds before and 2.4 seconds after that time is automatically backed up (s513). Is stored in the fourth memory device (5i) for history memory (s514), and at the same time output to the failure analysis screen of the output device (s515), to reproduce the situation before and after the alarm and event occurrence to analyze the abnormal cause To do it.

This data is stored in the fifth memory device 5i up to 20 times of the recent standard.

The second memory device 5f collects and stores data at a 1 msec period as shown by 'b' in FIG. 5 (s521, s522), and transmits the data to the output device 6 in real time upon user's request. By outputting to the real-time trend screen (s527, s528), it is possible to monitor the current electric control amount and torque in real time. In addition, when an alarm occurs or a predetermined event occurs (s523), the collected data is automatically backed up for 10 seconds before and 5 seconds later, and then transmitted to the fourth memory device 5i and stored (s524 and s525).

When the user requests, the trend backup data is output to the output device 6 on the failure analysis screen, and the cause before and after the occurrence of the abnormality is reproduced (s526).

In addition, the third memory device 5g collects and stores data at 20 msec intervals as shown in 'c' of FIG. 5A (s531 and s532), and transmits the data directly to the output device 6 when requested by the user in real time. The monitoring screen is output so that the amount of electric power and torque can be continuously monitored (s533, s534).

In addition, the data collected in 20msec period is transmitted to the control operation unit (5h) at all times, and analog data is recognized as alarm when exceeded compared with the set alarm reference value. It is recognized (s535). When such an alarm and / or event occurs, the alarm contents are registered in the alarm list, and at the same time, the alarm sound is output through the speaker (s536).

In addition, the 20msec period data also automatically backs up data for 2.5 minutes before occurrence and 0.5 minutes after occurrence (s537) when an alarm occurs and an event occurs (s537), and transmits and stores the data to the fourth memory device 5i (s538). . If requested by the user, the trend backup data is transferred from the fourth storage device 5i to the output device 6, and a failure analysis screen for reproducing the situation before and after a long event occurrence is displayed (s539).

Next, as described above, the fourth memory device 5i is a device for storing history data, and is based on data of 20 msec period (s541), and the collected 20 msec data is stored in the control operation unit 5g. The second, minute, hour, and day data are generated by a time trigger (not shown) of the control operation unit 5g and stored in the fourth storage device 5i (s542).

As shown in Fig. 5b, the second data takes one data per second among 20 msec period data and recognizes it as second data. The minute data is the maximum from 60 data for one minute. , Mean, median, and minimum value can be monitored separately. Hour data can be monitored by selecting one of the maximum, average, median, and minimum value of 60 minutes data. It is possible to monitor either the value or the minimum value (s543, s544).

Each second, minute, hour, and day data is displayed on the trend screen of the output device upon request by the user (D1), and these data show trends over time of facility operation and deterioration (s545).

Next, the torque data processing and diagnosis method will be described with reference to the flowchart of FIG. 6. The torque data is based on the 20 msec period data obtained from the third storage device 5g of the data collection device 5 as follows. Processed together and monitored.

The theoretical torque has a voltage, a current, and a rotation speed value related to the theoretical torque, and is calculated as shown in Equation 2 below (s602).

In the above, V is voltage, I is current, and N is rotation speed.

Therefore, when the user requests theoretical torque, voltage, current, and rotational speed data are sent to the output device 6, and the output device 6 calculates the theoretical torque based on Equation 2 above and displays the theoretical torque on the theoretical torque screen. (s603). This data is the output torque of the motor.

Next, when the processing and collection relationship of the shaft torque data is examined, the measured stress value is first converted into the shaft torque value according to Equation 1 (s604).

The torque value obtained here is further divided into a torque peak value (T _peak ) and a torque middle value (T _normal ), which are as follows.

That is, the rolling reduction signal is always checked to determine when the rolling reduction is 200 ton or more (s605), and the maximum torque value (T _peak ) and the torque middle value (from the collected data from one second before the rolling start time to the rolling completion point) _normal T) by finding the value obtains the _peak T and T _normal, and at the same time by counting the number of occurrences storing each data in the fourth memory device (5i) (s606, s607) .

The data collection accumulates the number of occurrences by T _noraml and T _peak by accumulating the number of times per day, the number of times per day, and the total number of times. The form of the data is as shown in FIG. 7A, and is output as a torque distribution upon user request (s608). The data indicates the distribution of loads applied to the rolling axis, the most ideal distribution being when the normal distribution, the more the bias to the right, the more the overload is applied to the rolling mill.

Next, a torque TAF is calculated (s608), which is defined by Equation 3 below.

TAF = T _peak / T _normal

The collected and calculated TAF data are continuously stored in the fourth memory device 5i by accumulating the rolling passes continuously in units of time based on the TAF value and the T _normal value at the time of collection.

At this time, the form of the data is shown in FIG. 7B, and is output on the TAF distribution map (e.g. 3) of the output device 6 when the user requests. The output method is T _normal on the X axis, TAF on the Y axis, and T _normal and TAF. The number of occurrences is displayed at a position corresponding to the number of occurrences in graphic form (s609).

For example, 1 to 500 times are "☆", 501 to 1000 times are "◇", 1001 to 5000 times are "■" and the like. This TAF distribution chart shows the degree of impact torque applied, and the TAF value is large when the play of the shaft rotation system progresses and the play is excessive or when rolling excessively. Indicates.

Next, the remaining life and prediction of the life of the spindle (s610 ~ s613), first to obtain the fatigue stress of the actual material of the spindle (spindle), the fatigue limit of the standard specimen as shown in SN Obtained from the curve, considering the following factors to calculate the fatigue stress of the actual material and the formula is as shown in Equation 4.

In Equation 4, τ _al is the fatigue stress of the material, τ _n is the fatigue stress of the standard specimen, S is the safety factor, Kt is the stress concentration coefficient, ζ ₁ is the surface effect coefficient, ζ ₂ is the dimensional effect Coefficient.

To obtain the fatigue stress of the actual material, first, the fatigue stress value for the standard specimen is read from the S-N curve of the spindle (Fig. 8). As an example, FIG. 8 shows the SN curve of the material SF60, where the horizontal axis represents the allowable frequency and the vertical axis represents the stress, as shown in this graph, the allowable stress value is 23.4 kg / mm 2 and above is the fatigue stress. This is an area that affects lifespan. From this graph, the fatigue stress of each step of the standard specimen is read, and the fatigue stress of the actual material is calculated based on Equation 4 with the fatigue stress of the standard specimen obtained here.

At this time, the fatigue stress of the obtained material is lower than the stress of the standard specimen. (K times, IK <1) And the fatigue stress value of the actual material obtained from the above Equation (4) is divided into 10 steps, allowing each step The number of times is read from the SN curve, and the allowable number of steps is N1, N2, N3 ... N10.

The fatigue stress acting on the spindle must then be obtained. This method converts the collected torque P _eak value from the torsional fatigue stress of the torsion. This is shown in Equation 5 below.

In the above, Zp is the extreme cross-sectional secondary moment.

Based on the above Equation 5, the actual torsional stress is obtained, and the torsional stress is divided into 10 steps with the same magnitude as the fatigue stress of the material obtained above, and the cumulative management is performed by counting the number of times of stress generation (rolling pass). . That is, the cumulative frequency of acting stress in one section is defined as the cumulative number of acts in n1 and 2 sections, and the number of acts allowed in n2 ... 10 sections is defined as n10.

When the user requests the stress distribution diagram, if the user transmits the accumulated Tpeak data stored in the data collection device and the data of the accumulated number of occurrences to the output device, the output device calculates the working torsional stress and calculates it on the stress distribution screen (M4). Displays the cumulative number of occurrences by torsional stress. In this case, the number of actual allowable fatigue stresses of the material is also indicated.

In the above, the remaining life and the life prediction are obtained as in the following Equations 6 and 7.

In the above, Dt is the current date, Da is the number of days available now, Lt is the current remaining life (%), L _-60 is 60 days ago remaining life (%).

In other words, the life expectancy is obtained by dividing the difference between the remaining lifespan 60 days ago and the current lifespan by 60 days, and the daily life reduction rate is obtained, and dividing the current remaining life by the daily life reduction rate, the number of available days is obtained. Life expectancy can also be determined by adding the number of future days to the current date.

Therefore, when the user requests the life expectancy diagram, the cumulative frequency for each section about the working torsion stress accumulated in the data collection device is transmitted to the output device, and the life expectancy screen (Eq. 5) is expressed by Equations 6 and 7 described above. The remaining life and life expectancy data are output to.

7C shows the torque distribution chart, the TAF distribution chart, the stress distribution chart, and the life expectancy screen, showing the data collection method, the contents displayed on the X and Y axes of the output screen, and the application effect.

As described above, the present invention constantly monitors the rolling motor and rolling mill shaft torque to guide the torque distribution, the form of load applied to the rolling mill due to the torque TAF distribution, and the defect of the rotating body, and the stress applied to the shaft. The cumulative management of has excellent effect to prevent the loss of spindle due to life expectancy in advance.

In addition, by providing comprehensive information of shaft torque, voltage, current, RPM, and control signal, it provides abnormal information in case of trouble or operation failure to help establish the cause analysis and countermeasures. Can improve.

Claims (7)

A strain gauge for detecting the torsion stress applied to the rotating shaft, A transmitter for transmitting the signal detected by the strain gauge from the rotor to the fixed side; A transmission / reception antenna installed at the rotating body and the fixed side to transmit and receive signals, A receiver that receives and reproduces a transmission signal, A data collecting device which receives each data inputted from the receiver and collects data in real time, and automatically backs up the data within a predetermined range before and after the occurrence of an event or an alarm and provides the output device as required; Output device that displays the theoretical torque and shaft torque based on the data sent from the data collection device and displays them on the screen, and displays the torque distribution chart, TAF distribution chart and life prediction chart on the screen so that the user can predict the equipment condition. Rolling mill diagnostic apparatus according to the shaft torque, characterized in that consisting of. The apparatus of claim 1, wherein the data collecting device is Torque signal, motor voltage, current, rotation speed, rolling reduction, operation signal, warning sign, and other signals necessary for diagnosis, heavy signal, analog signal input terminal and digital signal input terminal, A multiplexer for sequentially selecting the signals applied from the analog signal input terminal and the digital signal input terminal one by one at a moment, and transmitting the analog signals to the A / D converters and the digital signals to the first to third storage devices; An A / D converter for fast A / D conversion of the signal input from the multiplexer, First to fourth memory devices 5e to 5g and 5i for storing each data inputted from the A / D converter and the multiplexer at set cycles and backing up and outputting a predetermined range of data as required; Rolling mill according to the shaft torque, characterized in that the control operation unit for outputting the corresponding data stored in the first to fourth memory device to the output device 6 according to the alarm occurrence and / or event occurrence or the user's request Diagnostic device. The apparatus of claim 2, wherein the data collection device Data collected at 0.1msec cycles are continuously stored in the first storage device, and when 20msec cycle data occurs, an alarm occurrence (over-the-baseline) and an event (heavy failure) occur or a user request signal is displayed. Back up the data within a predetermined time before and after and store it in the fourth memory device and output it to the output device, Collect data at 1msec period and store it in the second memory device, and then send it to the output device in real time when the user requests it, or in case of an alarm or a predetermined event, back up the data within a predetermined time before and after the occurrence and store it in the fourth memory device Provide it to the output device when requested by the user, It collects data at 20msec period and stores it in the third memory device, and transmits it to the output device in real time when requested by the user.The analog data is recognized as an alarm occurrence when exceeded compared with the set alarm reference value, and the digital data is Determining whether it is a warning site or a heavy site and recognizing it as an event occurrence.When an alarm and / or event occurs, it registers the alarm contents in the alarm list and outputs an alarm sound, and automatically backs up data in a predetermined range before and after the occurrence. A rolling mill diagnostic device according to shaft torque, which is transmitted to a storage device and an output device. The method of claim 1, wherein the diagnostic device When the user requests theoretical torque, the user receives the voltage, current, and rotational speed data from the data collection device. (N is rotational speed, V is voltage, I is current) and the theoretical torque is calculated, and the theoretical torque screen is displayed on the output device. The method of claim 1, wherein the diagnostic device Data inputted from the data collection device; Where T is the torque, G is the lateral modulus, D is the shaft diameter, and ε is the stress After calculating the axial torque by substituting in, the rolling reduction signal is always checked to determine the rolling time, and then the maximum torque value (T _peak ) and the middle torque value (T _normal ) are collected from the collected data from a predetermined time before the rolling start time to the rolling completion time. And rolling the torque distribution diagram by accumulating the respective data by counting the number of occurrences at the same time as acquiring the value). The method of claim 1, wherein the diagnostic device TAF is calculated from the torque maximum value (T _peak ) and the torque middle value (T _normal ) according to TAF = T _peak / T _normal , and then the TAF value and the torque middle value T _normal at the time when the calculated TAF data are collected. Continuously accumulate in rolling time unit on the basis of the standard, and display the number of occurrences at the torque mid value T _normal on the X axis, the TAF on the Y axis, and the position corresponding to each torque mid value T _normal and TAF. Rolling machine diagnostic apparatus according to the shaft torque, characterized in that for outputting the TAF distribution. The method of claim 1, wherein the diagnostic device The fatigue limit of the standard specimen is obtained from the S-N curve, and the fatigue stress of the actual material is calculated by the following equation. Where τ _al is the fatigue stress of the material, τ _n is the fatigue stress of the standard specimen, S is the safety factor, Kt is the stress concentration factor, ζ ₁ is the surface effect factor, ζ ₂ is the dimensional effect factor .) Among the calculated fatigue stresses of the actual material, the allowable stress value is divided into predetermined steps, expressed as the allowable frequency for each step, and the value of the applied fatigue stress of the torsion on the shaft is converted from the collected torque P _eak value as shown below. and, (Where Zp is the extreme quadratic moment), By dividing the torsion stress into predetermined steps with the same magnitude as the fatigue stress of the material, cumulative management of the number of times the stress generation step by step, to represent the cumulative number of times generated by the torsional stress, Obtain the remaining life and life expectancy values as (Where Dt is the current date, Da is the number of days available, Lt is the current remaining life (%), and L _-60 is the remaining life (%) 60 days ago.) And a stress distribution diagram for displaying the cumulative frequency for each section of the torsional stress, and the remaining life and life prediction data when the user requests the life prediction chart.