JPH11262842A - Abnormal temperature detecting device for sliding part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an abnormal state by adding a rising rate of a measured temperature to a change in the rising rate of the measured temperature. SOLUTION: The temperature of a bearing is measured in a fixed period and a temperature difference from each measured temperature is determined as a temperature rising rate for every measurement. Further, a difference of the rising rate of each temperature rising rate is determined as a rate of change of the temperature rising rate. Till prescribed time from the starting of an operation, whether a measured temperature is lower than an allowable maximum temperature or not and whether the temperature rising rate is lower than the allowable temperature rising rate or not are judged. If each is higher, the effect is displayed on a display device 7 and is outputted to an alarm device 8 and an alarm is given. When the rate of change in the temperature rising rate is positive after prescribed time passes, the state is defined as an abnormal state to be a symptom of an abnormal rise in temperature, and the display to the effect is performed and an alarm is given in the same way. When each of the temperature rising rate or the rate of change is an allowable temperature rising rate or below or negative or zero, the state is defined as a normal operating state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting an abnormal temperature of a sliding part, which detects an abnormal state when the temperature of a sliding part such as a bearing in a general industrial machine rises abnormally.

[0002]

2. Description of the Related Art In a mechanical device such as a forging press machine, if a burning phenomenon occurs on a sliding portion such as a bearing, not only the machine is stopped but also a failure is caused. The cause of the burning is insufficient lubrication oil supply, lack of lubrication oil due to excessive load, etc.
Metal contact (wiping) due to foreign matter biting or the like can be considered.

[0003] In order to prevent this burning, there has conventionally been devised a technique of measuring the temperature of a sliding portion and detecting an abnormal state based on the measured value. As the technique, detection is performed by determining whether or not the measured temperature is equal to or higher than the temperature in an abnormal state. It is detected whether or not the measured temperature rise rate exceeds an allowable value (Japanese Patent Application Laid-Open No. 53-148647). The measured temperature rise rate is determined as a function of temperature, and the reference function and the temperature rise rate based on the measured temperature are used. There is a method of detecting whether or not the difference is within an allowable value (JP-A-56-129524).

[0004]

By the way, as shown by the curve a in FIG. 1, when the machine is started, the temperature T of the sliding portion rises rapidly first, and then the temperature rises in the sliding portion. As the temperature approaches the collision temperature Ta, the temperature rise rate Td
Gradually decreases and changes to almost zero near the balance temperature Ta. The equilibrium temperature Ta is a temperature when the amount of heat generated by the sliding portion and the amount of heat radiated from the sliding portion to the outside are balanced. Atmospheric temperature (ambient temperature), cooling water temperature, shaft rotation speed, lubricating oil It is determined by viscosity and the like.

[0005] In the temperature characteristics having such properties, according to the above-mentioned technology, when the sliding portion abnormally rises at a low temperature, the temperature curve shows that the temperature T of the sliding portion abnormally rises as shown in FIG. It takes time t ₀ from the start time to reach the maximum allowable temperature T _0, and it can be recognized that the bearing temperature T is in an abnormal state only after the elapse of the time t ₀ . For this reason, there is a problem that the bearing portion may be seized before an appropriate measure such as the operation stop measure is performed.

[0006] According to the art, as can be understood from the characteristic curve a 1, to lower gradually the temperature change rate Td, it is difficult to determine the allowable temperature rise rate Td _0. That is, since the rise rate Td is small in the high temperature range, if the rate is made to correspond to the rate, it is determined that the temperature is not abnormal in the low temperature range even though it is not abnormal, and conversely, the rise rate Td is large in the low temperature range. Therefore, if you correspond to that rate,
In the high temperature range, it is determined that there is no abnormality even though it is abnormal.

The above technique has no problem because the temperature rise rate Td is determined as a function and the allowable temperature rise rate Td ₀ at each measured temperature is determined. However, in order to determine the reference function, it is necessary to accurately measure the temperature rise characteristics of the machine during normal operation, and for that purpose, a plurality of temperature measurement positions are required. Is economically disadvantageous. Also, for example, in a hot forging press machine, although the temperature of the main bearing at the initial stage of operation does not differ from room temperature, the temperature of the die increases, the billet in a high temperature heating state, heat radiation from the induction heater, Due to factors such as a rise in the brake temperature, the temperature of the main bearing is not raised only by frictional heat caused by rotation of the metal part. Thus, the temperature rise rate T
Since d depends on the surrounding atmosphere, a reference function that also takes into account the surrounding atmosphere is required, and the determination of the function is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to easily and accurately detect an abnormal state.

[0009]

In order to solve the above-mentioned problems, the present invention focuses on the fact that, when the temperature rise curve a in FIG. 1 is normal, the temperature rise rate gradually decreases. If the change in the rate of temperature rise tends to increase, it is a sign of an abnormal state. For this reason, the temperature of the sliding portion is measured, and an abnormal state of the sliding portion is detected based on a change in the measured temperature rise rate.

In this detection, the abnormal temperature curve b in FIG.
As can be understood from the above, even if the temperature rise rate Td is abnormal in the early stage of the operation, the rate of change is close to zero, so that the detection means may not be able to detect the abnormality. For this reason, it is preferable to detect an abnormal state of the sliding portion by taking into account the measured temperature rise rate in addition to the change in the measured temperature rise rate Td.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment is shown in FIGS.
A temperature sensor 1 including a resistance temperature detector, a thermocouple, and the like is attached to a bearing portion such as a crankshaft of a hot forging press,
The signal (measured temperature T _(n) ) is input to a microprocessor (computing unit) 3 through an A / D converter 2, and an operation start signal or a rotation detection signal 4 is input to a microprocessor via a contact input interface 5. Input to the processor 3. The maximum allowable temperature T ₀ and the allowable temperature increase rate Td ₀ in a low temperature range (for example, between t _{0 in} FIG. 1) obtained by experiments, actual operations, and the like are input from the storage device 6 to the microprocessor 3. The calculation result is output to the display device 7 and the alarm device 8.

FIG. 3 shows the operation of the abnormality detecting device having this configuration.
The bearing temperature T _(n) is set to a constant cycle,
For example, measurement is performed at intervals of 50 msec,
_{(n-1 )} and the temperature difference (T _(n) -T _(n-1) ) as the temperature rise rate T
d _(n) , and this action is performed for each measurement, and the difference (Td ₎ between the temperature rise rate Td _(n-1) and the previous temperature rise rate Td _(n-1)
(n) -Td _(n-1) ) is obtained as a rate of change Tdd _(n) of the temperature rise rate.

From the start of the operation to a predetermined time t ₀ , whether the measured temperature T _(n) is lower than the allowable maximum temperature T ₀ and whether the temperature rise rate Td is lower than the allowable temperature rise rate Td ₀ . If the respective values are high, the fact is indicated on the display device 7 and output to the alarm device 8 to give an alarm.

After the elapse of the predetermined time t _0, the rate of change Tdd _(n) of the temperature rise rate is positive, that is, (Td _(n) > T ₎
In the case of d _(n-1) ), the temperature curve a is turned upward and an abnormal state is indicated, which is a sign of an abnormal rise in temperature. Temperature increase rate Td _(n), or its rate of change Tdd _(n) is the allowable temperature increase rate Td ₀ or less, or negative or if _{zero, T (n-1) =} T (n), Td (n-1 ₎
= Td _(n) and normal operation. In this case, like in consideration of the measurement error, width Td _(n) exceeds Td _0,
A width _where Tdd _(n) exceeds zero and becomes positive (allowable change width Tdd ₀ of the temperature rise rate) is appropriately provided, and within the width,
Similarly, a normal operation state may be set.

In this embodiment, the above technique can be used in combination. At this time, (Td _(n) > Td ₀ )
May be omitted.

[0016]

As described above, according to the present invention, the abnormal state is detected based on the rate of change of the rate of temperature rise, so that it is possible to perform highly accurate detection with less influence of the ambient temperature. . Further, since it is not affected by the temperature rise characteristics, there is no need to obtain a characteristic curve suitable for the characteristics as in the above-described technology, and there is no complicated control.

[Brief description of the drawings]

FIG. 1 is a graph showing a temperature rise characteristic of a sliding portion.

FIG. 2 is a detection block diagram of one embodiment.

FIG. 3 is a detection flowchart of the embodiment.

[Explanation of symbols]

T ₀ allowable maximum temperature T _(n) measured temperature Td, Td _(n) temperature rise rate Td ₀ allowable temperature rise rate Tdd, Tdd _(n) change rate of temperature rise rate 1 temperature sensor 3 microprocessor 6 storage device 7 display device 8 Alarm device

Claims (2)

[Claims] The temperature of a sliding portion is measured, and the measured temperature T
_(n) abnormal temperature detecting device of the sliding portion which is adapted to detect the abnormal state of the sliding portion in the rate of change Tdd _(n) of the increase rate Td _(n) of the. Wherein the rate of change of the increasing rate of the measured temperature _{T (n) Td (n)} Tdd (n), the increase rate Td of the measured temperature T _(n)
2. The abnormal temperature detecting device for a sliding part according to claim 1, wherein an abnormal state of the sliding part is detected in consideration of _(n) .