JPS63246502A - Bearing seizing preventing device - Google Patents

Abstract

PURPOSE:To prevent seizing and reduce damage by storing a current value corrected by the voltage value of an electric motor in a memory circuit which is renewed at every defined time and operating a bearing seizing preventing circuit when the corrected current value becomes above a stored current value. CONSTITUTION:An ammeter 3 and a voltmeter 4 are provided in the power circuit 2 of an electric motor 1 and input signals from converters 5, 6 for carrying out the digital convertion of a current value and a voltage value into a correction operating device 7, respectively, to correct fluctuation in the current value due to fluctuation in voltage, and this corrected value is outputted into a sampling device 8. A sampling signal oscillator 12 is connected to the sampling device 8 to output a sampling current value to a comparator 9 as a memory comparison value via a memory device 13. And, when the current value of the correction operation device 7 is larger than the memory comparison value, a seizing preventing circuit is operated via an AND circuit 14 and a transistor 15. Thereby the seizing of bearing can be prevented reducing damage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bearing seizure prevention device for a rotating shaft driven by an electric motor.

[Prior art] For example, if the bearings of the crankshaft, connecting rod, etc. in a high-speed automatic press were to seize due to lack of lubricating oil, etc., conventionally, an operator would visually check the abnormal current using an electric motor ammeter, etc. The operator used an ammeter to read the normal current value, input it manually into the current detection device, and when it detected that the current value exceeded the range, the electric motor was stopped. .

In addition, a temperature sensor is installed on the bearing to detect an abnormal rise in bearing temperature during seizure, and a resistor installed in the input line of the electric motor can detect heat generation due to excessive current during seizure to prevent bearing seizure. was detected and the electric motor was automatically stopped.

[Problems to be Solved by the Invention] However, manual monitoring by workers lacks reliability due to oversights.

Furthermore, in both cases, there is a time delay, and detection and stopping occur only after the bearing is completely seized. This prevents abnormal presses caused by abnormal rotation of the shaft after seizing, but the bearing becomes unusable and must be replaced. In addition, the shaft also requires repair such as polishing.

The present invention solves the above-mentioned problems, automatically detects bearing seizure as early as possible, and activates protective functions such as increasing lubricating oil or decelerating or stopping, thereby minimizing damage caused by seizure. The aim is to keep it to a minimum.

[Means for Solving the Problems] The present invention provides an electric motor power supply circuit with an ammeter and a voltmeter, and a correction calculator that corrects the current value from the ammeter with the voltage value from the voltmeter. A memory circuit is provided to update and store the corrected current value output from the correction calculator at regular intervals, and a comparator is provided to compare the latest stored current value with the corrected current value. The present invention is characterized in that the bearing anti-seizure circuit is configured to operate when the current exceeds a memorized current value.

[Function] The electric power supplied to the electric motor is measured by an ammeter and a voltmeter, a current value corrected for voltage value fluctuations is calculated in a correction calculator, and the corrected current value is stored in a memory circuit at regular intervals. sampled, updated and stored,
The comparator compares the latest stored current value and the corrected current value, and when the corrected current value becomes larger than a certain value, a bearing anti-seizure circuit such as a bearing lubricating device or rotation deceleration or stop device is activated. do.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show an embodiment of the present invention. For example, an ammeter 3 and a voltmeter 4 are attached to the power supply circuit 2 of an electric motor 1 of a high-speed automatic press, and the ammeter 3 converts the current value into a voltage. A converter 5 is provided for converting and further converting to DC and digitally converting,
The voltmeter 4 is provided with a converter 6 that converts the voltage value into direct current and digitally converts it.

A computation unit 7 corrects each digital signal from each converter 5.6.
The current value fluctuations based on voltage fluctuations are corrected, and the corrected values are output to the sampler 8 and the comparator 9.

The sampler 8 includes a sampling signal that counts pulse signals from a pulse oscillator IO that oscillates a constant pulse signal, such as a quartz oscillator, and that emits a sampling signal every pulse number set by a pulse number setting device 11. An oscillator 12 is connected so that the current value can be sampled at regular intervals.

The sampling current value is output to the memory 13, and the memory 13 updates and stores the latest current value, and also outputs the latest stored value to the comparator 9. The stored comparison value is compared with the current value from the comparator 9, and when the current value becomes larger than the stored comparison value by a certain amount or more, an activation signal is sent to the transistor 1 via the AND circuit 14.
5.

In addition, the rotation speed signal from the rotation speed detector 16 that detects the rotation speed of the rotating shaft and the rotation speed set by the rotation speed setting device 17 are outputted to the comparator 18 and compared, and the detected rotation speed is determined as the set rotation speed. In the above case, an ON signal is output to the AND circuit 14, and in the same case, an OFF signal is output to the AND circuit 14.

The transistor 15 is connected via a relay 19 to operate a seizure prevention circuit such as a lubricating oil supply device, a rotating shaft deceleration/stop device, etc.

In the above, it is better that the interval of sampling time Δt determined by the set number of pulses is as short as possible.
Determine as appropriate depending on the accuracy of other equipment and the actual conditions of the rotating shaft.

Further, the comparison value in the comparator 9 may be determined to be abnormal if the measured corrected current value exceeds the stored value even slightly, or if it exceeds a certain value by AA after cutting a certain noise, it is determined to be abnormal. It may be determined that The level for cutting this noise is appropriately set depending on actual conditions.

With the above configuration, when the electric motor 1 is turned on to start the press line, the press line gradually increases its operating speed and reaches a steady speed. During this time, the rotation speed of the rotating shaft is detected by the rotation speed detector 16, and a detected rotation speed signal is sent to the comparator 18. compared to numbers. If the detected rotational speed is lower than the set rotational speed, an off signal is sent to the AND circuit 14, the AND circuit 14 is cut off, and the signal from the comparator 9 is cut off.

This automatically cuts out the unstable period at startup.

When the detected rotational speed exceeds the set rotational speed, an on signal is sent from the comparator 18 to the AND circuit 14.

Also, the current and voltage of the electric power supplied to the electric motor l are
They are constantly measured by an ammeter 3 and a voltmeter 4, respectively.

For example, if one of the bearings on the rotating shaft runs out of lubricating oil,
When the load on the electric motor 1 begins to increase, the current value immediately increases as shown in FIG. However, changes in the amount of current also occur due to changes in voltage. Therefore, the ammeter 3
The current value measured by is converted into a voltage by a converter 5, and further converted into a direct current and digitally converted, and then sent to a correction calculator 7.
However, the voltage value measured by the voltmeter 4 is also converted into DC by the converter 6, converted into digital data, and sent to the correction calculator 7, where the fluctuation of the current value based on the voltage fluctuation is corrected. Corrected.

The current value corrected by the correction calculator 7 is sent to a sampler 8 and a comparator 9. The sampling signal oscillator 12 counts the pulse signals from the pulse oscillator 10, and the sampling signal is sent to the sampler 8 every pulse number set by the pulse number setting device 11, and the corrected current value at that moment is Sampler 8
The data is taken out and sent to the storage device 13. The storage device 1
3, the newly sent current value is updated and stored, and the latest stored current value is sent to the comparator 9.

Therefore, the comparator 9 constantly compares the just-measured corrected current value with the latest updated stored current value, and when the difference between the measured current value and the stored current value is 0, the rotating shaft rotates normally. I know what you're doing. However, if this difference becomes a positive value, it means that the current value has increased compared to when it was stored, so a command signal to activate the anti-seize circuit is sent to the transistor 15 through the AND circuit 14.

When the transistor 15 receives the command signal, the relay 19 is turned on, and the lubricating oil supply device supplies lubricating oil to the bearing, or the rotation of the rotating shaft is decelerated or stopped.

As a result, seizure of the bearing can be prevented or stopped at an early stage, and damage can be kept to a small level.

It should be noted that the present invention is not limited to the above-described embodiments, and that the sampling circuit may be a differential circuit, a SIRISK may be used instead of a transistor, and the protection means for the anti-seize circuit may be any arbitrary one. It goes without saying that various changes can be made without departing from the gist of the present invention, such as combinations or the omission of the AND circuit.

[Effects of the Invention] As described above, according to the bearing anti-seizure device of the present invention,
An ammeter and a voltmeter are installed in the input system of the electric motor, and the corrected current value sampled and stored at regular intervals is compared with the corrected measured value, and when the measured value exceeds the stored value, the anti-seize circuit is activated. Therefore, when the load on the electric motor increases slightly and the amount of current increases, the anti-seizure circuit immediately activates to supply oil, decelerate or stop the rotation, and prevent the bearing from seizing. It exhibits various excellent effects such as minimizing damage to bearings.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the apparatus of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between time and current value during bearing seizure. 3 is an electric motor, 3 is an ammeter, 4 is a voltmeter, 7 is a correction calculator, 8 is a sampler, 9 is a comparator, 12 is a sampling signal oscillator, 13 is a memory, 14 is an AND circuit,
15 indicates a transistor. Patent output five people

Claims (1)

[Claims] 1) Install an ammeter and a voltmeter in the electric motor power supply circuit,
A correction calculator for correcting the current value from the ammeter with a voltage value from the voltmeter is provided, a storage circuit is provided for updating and storing the correction current value output from the correction calculator at regular intervals, A bearing seizure prevention device characterized in that a comparator is provided to compare the latest stored current value and the corrected current value, and the bearing seizure prevention circuit is configured to operate when the corrected current value exceeds the stored current value. Device.