JP2006336770A - Pneumatic lubrication oil supply device and its oil supply pipe leakage detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and inexpensively detect leakage when occurring in an oil supply pipe. <P>SOLUTION: This pneumatic lubrication oil supply device uses compressed air for supplying lubrication oil to a lubricated object 3 via the oil supply pipe 2c. It comprises two pressure holding valves 20a, 20b provided in the oil supply pipe 2c at a space in the flowing direction of the lubrication oil for holding pressure in the oil supply pipe 2c when stopping the supply of the compressed air, and a pressure detector 21 for detecting pressure in the oil supply pipe 2c between the two pressure holding valves 20a, 20b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating oil supply device, and more particularly to a pneumatic feed type (oil-air lubrication type) lubricating oil supply device that uses compressed air to send lubricating oil to an object to be lubricated, and a leak detection method for the oil supply piping. It is.

  For example, in a rolling mill used in a steel mill or the like, a large number of rollers such as rolling rollers are arranged, and the rotation shafts of the respective rollers are supported by bearings. In order to lubricate the bearing, it is effective to continuously supply a small amount of oil. Therefore, an oil-air lubrication type lubricating oil supply device as described in Patent Document 1 below is used.

  This lubricating oil supply device supplies lubricating oil and compressed air from a main unit to a mixer, mixes lubricating oil and compressed air to generate oil air, and is subject to lubrication through the oil supply pipe. Supply to the bearing.

JP-A-8-21598

  In a pneumatic feed type lubricating oil supply device, if air leakage occurs due to damage to the oil supply piping or joints, the oil / air may not be sent properly, which may result in insufficient lubrication. There is also a risk. Therefore, how to detect a leak is an important issue.

  One method for detecting this leak is to measure the pressure in the oil supply pipe with a pressure gauge. This is because when the leak occurs, the pressure in the oil supply pipe decreases.

  However, when the pressure drop in the oil supply pipe is slight, it is considered that the deterioration of the seal of the bearing, which is the object to be lubricated, is caused in addition to the leak in the oil supply pipe. A shaft box that houses the bearing is provided with a seal that is in sliding contact with the shaft, so that the lubricant supplied to the shaft box can be held to some extent by this seal. This is because when the seal deteriorates, the amount of air released from the axle box increases.

  Therefore, the leak detection method that merely measures the pressure in the oil supply pipe is useful when the pressure drop in the oil supply pipe is extremely large, but if the pressure drop in the oil supply pipe is slight, It is impossible to specify whether the leak is in the oil supply pipe or the seal is deteriorated. In addition, a high-performance pressure gauge is required to detect a slight pressure drop, which increases the cost.

  On the other hand, in Patent Document 1, in order to detect a leak, a fluid passage detector is disposed immediately before the bearing to be lubricated, and the passage of compressed air and lubricating oil is detected by the fluid passage detector. ing.

  This fluid passage detector includes an acrylic tube that forms a flow path of oil air continuously to the oil supply pipe, a float ball accommodated in the tube, and a float ball directed toward the upstream side in the lubricating oil supply direction. And an urging spring. When oil air is flowing normally in the oil supply piping, the float ball moves against the spring due to the pressure, and if the oil supply piping leaks upstream from the fluid ventilation detector, the resistance decreases. Therefore, the float ball moves upstream. The movement of the float ball is detected visually or mechanically and optically.

  In the case of this technique, when the seal of the bearing is deteriorated, the flow rate of the oil air flowing through the oil supply pipe is increased, and the float ball moves downstream against the spring. Therefore, since the behavior different from the leakage of the oil supply pipe is taken, both can be distinguished.

  However, this fluid passage detector determines whether or not the lubricant is supplied to the bearing. If a leak occurs in the oil supply pipe between the fluid passage detector and the bearing, the lubricant is supplied. Since it cannot be determined whether or not, it must be provided immediately before the bearing. Since the bearing is in an apparatus such as a rolling mill, if a fluid passage detector is provided immediately before the bearing, it is practically impossible to detect the float ball by visual inspection. Even when the movement of the float ball is detected mechanically and optically, it is necessary to provide mechanical connection, wiring, piping, etc. between the fluid passage detector and the detection monitor, etc. Cost increases.

  The present invention has been made in view of the above circumstances, and provides a pneumatic feed lubricant supply device and a leak detection method thereof capable of reliably and inexpensively detecting a leak occurring in an oil supply pipe. For the purpose.

  The invention according to claim 1 is the pneumatic feeding type lubricating oil supply device in which the lubricating oil is supplied to the object to be lubricated by compressed air through the oil supply pipe. Two pressure holding valves provided at intervals and capable of holding the pressure in the oil supply pipe when the supply of compressed air is stopped, and a pressure detector for detecting the pressure of the oil supply pipe between the two pressure hold valves And.

  The invention according to claim 2 is characterized in that the pressure holding valve is constituted by a check valve that allows the flow of compressed air and lubricating oil to the object to be lubricated and prevents the flow in the reverse direction. .

  A third aspect of the present invention is a method for detecting a leak in an oil supply pipe in the pneumatic feed lubricating oil supply apparatus according to the first aspect, wherein the supply of compressed air is temporarily interrupted and the pressure of the interrupted oil supply pipe Is detected by a pressure detector, and the presence or absence of a leak is discriminated based on the temporal variation of the pressure.

  (1) According to the present invention, in order to detect a leak in the oil supply pipe, the supply of compressed air is stopped, the pressure in the oil supply pipe is held between the two pressure holding valves, and the pressure is detected by the pressure detector. . When there is no leak in the oil supply pipe, the pressure fluctuation with time is small and the pressure gradually decreases. On the other hand, if a leak occurs in the oil supply pipe, the pressure in the oil supply pipe rapidly decreases. Therefore, the presence or absence of a leak can be accurately determined from the difference in pressure fluctuation.

  (2) Since it is only necessary to provide two pressure holding valves and a pressure detector in order to detect a leak in the oil supply pipe, the apparatus can be configured simply and inexpensively.

  (3) Since the pressure detector may be provided at any position between the two pressure holding valves, when the upstream pressure holding valve is arranged close to the mixer, the pressure detector can A pressure detector can be provided at a remote position, and monitoring of the pressure detector is facilitated.

  (4) When a check valve is used as the pressure holding valve, the apparatus can be configured at a lower cost.

  FIG. 1 is a configuration diagram of the entire system of a lubricating oil supply apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a mixer that mixes compressed air supplied from the main unit 15 and lubricating oil to generate oil air. The mixer 1 is provided with a lubricating oil supply port 1 a and a compressed air supply port 1 b and a plurality of oil air outlets. In the illustrated example, three outlets 1c, 1d, and 1e are provided.

  The outlets 1c, 1d, and 1e are connected to the oil supply pipes 2c, 2d, and 2e, respectively. Connected. The lubrication target 3 of the present embodiment is a bearing that rotatably supports a rolling roll or the like in a rolling mill.

  One of the oil supply pipes 2d is provided with a distributor 4 that distributes oil air into a plurality of parts. The distributor 4 shown in the figure divides the oil air flowing in from the supply port 4a into four equal parts and discharges them from the distribution outlets 4b, 4c, 4d, 4e, and is distributed to the distribution outlets 4b, 4c, 4d, 4e. Oil supply pipes 5b, 5c, 5d, and 5e are connected, and each distribution oil supply pipe 5b, 5c, 5d, and 5e is connected to a lubrication target.

  As shown in FIG. 2, the bearing 3 that is an object to be lubricated is accommodated in a space formed in the axle box 6. The shaft box 6 is provided with a seal device 8 that is in sliding contact with the rotary shaft 7. The seal device 8 substantially seals the arrangement space of the bearing 3 so that the oil supplied to the arrangement space can be held to some extent. It has become.

  As shown in FIG. 1, the axle box 6 is provided with a lubricating oil supply port 6a and a discharge port 6b. The supply port 6a is connected to the oil supply pipes 2c, 2e, 5b to 5e, and is connected to the discharge port 6b. The drain pipe 9 is connected, and the lubricating oil supplied to the bearing 3 returns to the oil tank 10 through the drain pipe 9. However, there is a case where the drain pipe 9 is not constructed because of cost. In this case, the oil-air air overcomes the sealing pressure of the sealing device 8 (FIG. 2) and is released into the atmosphere, and the discharge port 6b is blocked. It becomes the composition which does not have from the beginning.

  The lubricating oil supply apparatus having the above configuration is provided with detecting means for detecting leaks in the oil supply pipes 2c to 2e and 5b to 5e. The detection means includes a pressure holding mechanism 20 that holds the pressure in the oil supply pipes 2c to 2e, 5b to 5e, a pressure detector 21 that detects the pressure in the oil supply pipes 2c to 2e, and 5b to 5e, and a leak is detected. And informing means (not shown) for informing that when it is done.

  In the pressure holding mechanism 20 of this embodiment, check valves (pressure holding valves) 20a and 20b are used. The check valves 20a and 20b are provided at two locations on the upstream side and the downstream side of the oil supply pipes 2c to 2e and 5b to 5e. The upstream check valve 20 a is provided in the vicinity of the outlets 1 c to 1 e of the mixer 1, and allows the flow of oil air to the bearing 3 side and prevents the reverse. The check valve 20b on the downstream side is provided in the vicinity of the upstream side of the bearing 3 or directly in the axle box 6, and allows the flow of oil air to the bearing 3 side, but prevents the reverse.

  The pressure detector 21 includes a pressure gauge, a pressure switch, a pressure sensor, and the like, and is provided between the upstream check valve 20a and the downstream check valve 20b. The notification means is constituted by an alarm, a lamp, and the like.

[Operation of this embodiment]
Hereinafter, the operation of the lubricating oil supply device of the present embodiment will be described.
The lubrication supply apparatus according to the present embodiment performs a normal operation for lubrication and an inspection operation for leak detection. In normal operation, lubricating oil and compressed air are supplied to the mixer 1 and discharged from the mixer 1 as oil air. Oil air is supplied to the axle box 6 of the bearing 3 which is a lubrication object through the oil supply pipes 2c to 2e, 5b to 5e and the distributor 4. The oil after lubricating the bearing 3 is returned from the drain pipe 9 to the oil tank 10.

  The normal operation is continuously performed while lubrication is necessary, while the inspection operation is performed by temporarily stopping the normal operation. Specifically, the main unit 15 stops the supply of compressed air.

  Oil air moves oil droplets along the inner wall surfaces of the oil supply pipes 2c to 2e and 5b to 5e by the flow of compressed air. For example, air leaks due to breakage of pipe joints and pipes, If there is an air leak from a multi-clamp or the like inserted in the middle of the piping, this immediately leads to a stop or decrease in the supply of lubricating oil, which may result in insufficient lubrication. Particularly, since there are hundreds of bearings for heavy machinery such as rolling mills and continuous casting equipment, it is impossible for humans to visually check for leaks.

  If the oil supply pipes 2c to 2e and 5b to 5e are damaged, a large amount of compressed air is released, and the pressure in the pipe drops rapidly, so that the leak can be detected by the pressure detector 21 even during normal operation. However, even if a pressure drop phenomenon due to a slight leak other than that occurs, it cannot be determined whether this is due to an air leak or a deterioration of the sealing device. This is also apparent from Experiment 1 described later.

  Therefore, in the lubricating oil supply apparatus of the present invention, even a slight leak is detected by performing the following inspection operation to prevent insufficient lubrication of the lubrication target object 3.

A specific detection method is as follows.
(1) First, during the normal operation, the supply of compressed air is stopped for a certain time (about several minutes).
(2) While the supply of compressed air is stopped, the pressure in the oil supply pipes 2c to 2e and 5b to 5e between the two check valves 20a and 20b is measured by the pressure detector 21.
(3) The pressure in the oil supply pipes 2c to 2e and 5b to 5e decreases with the passage of time regardless of the presence or absence of leakage. However, if there is a leak, even a slight leak will cause the pressure to drop more rapidly than in a normal state. This is clear from Experiment 2 described later. When the pressure drop is rapid and the pressure becomes 0 within a predetermined time (for example, within 30 seconds to 1 minute), it is determined that there is a leak in the oil supply pipe.
(4) When it is determined that there is a leak in the oil supply pipe, an alarm is issued by the notification means.

[Effect of this embodiment]
Therefore, according to the present embodiment, the following effects are obtained.
(1) The supply of compressed air is stopped during normal operation, and the pressures in the oil supply pipes 2c to 2e and 5b to 5e are held by the two pressure holding valves 20a and 20b, and the pressure is detected by the pressure detector 21. In addition, since the presence or absence of a leak is determined by the change over time of the pressure, it is possible to reliably detect the leaks in the oil supply pipes 2c to 2e and 5b to 5e even if the leak amount is small. It can be distinguished from the deterioration of the sealing device 8.

  (2) Since it is only necessary to provide two check valves 20a and 20b and a pressure detector 21 in each of the oil supply pipes 2c to 2e and 5b to 5e in order to detect a leak, the apparatus is configured simply and inexpensively. Can do.

  (3) Since the pressure detector 21 may be provided at any position between the two check valves 20a and 20b, when the upstream check valve 20a is provided immediately after the mixer 1, The pressure detector 21 can be provided at a position further away from the object to be lubricated, and monitoring of the pressure detector 21 is facilitated.

  (4) When the check valves 20a and 20b are used as the pressure holding valves, the lubricating oil supply device can be configured at a lower cost.

  (5) Since an alarm is issued when a rapid pressure drop is detected in the oil supply pipes 2c to 2e, 5b to 5e during the inspection operation, the operator can quickly recognize the abnormal state and immediately Can be transferred to repair work.

Other Embodiment
The present invention is not limited to the above-described embodiment. For example, the design can be appropriately changed as follows.
(1) The pressure holding valve is not limited to a check valve, and an open / close valve (solenoid valve) may be used. In this case, when starting the inspection operation, the solenoid valve may be closed simultaneously with the stop of the supply of compressed air, and the pressure of the oil supply pipe may be maintained between the upstream and downstream solenoid valves.

(2) When the distributor 4 is provided in the oil supply pipe, the downstream check valve 20 b can be disposed in the vicinity of the upstream side of the distributor 4. In this case, a leak upstream of the distributor 4 can be detected.

(3) The object to be lubricated is not limited to a bearing, but refers to a portion where various devices and parts thereof can be lubricated.

[Experiment 1]
The applicant of the present application used the experimental apparatus shown in FIG. 3 to artificially cause a leak in the oil supply pipe during normal operation, and examined the pressure fluctuation in the oil supply pipe.

  In FIG. 3, a pressure reducing valve 32, a pressure gauge 33 for setting a supply pressure, a flow meter 34 for setting the amount of supply air, and a supply of compressed air are turned on and off in a supply pipe 31 for compressed air to the mixer 1. A solenoid valve 35 is provided. The pressure reducing valve 32 is set to 0.3 MPa. The amount of compressed air to be supplied is 25 NL / min. The oil supply pipe 2c has an outer diameter of 6 mm, a thickness of 0.8 mm, and a length of 10 m. The cracking pressure of the check valve 20a is 0.005 MPa, and the cracking pressure of the check valve 20b is 0.1 MPa.

  A branch pipe 36 is connected to the oil supply pipe 2 c, and an open / close valve 37 and a flow meter 38 are provided in the branch pipe 36. The on-off valve 37 artificially generates a leak in the oil supply pipe 2c, and the flow meter 38 sets the leak amount. Pressure detectors P1 and P2 are provided between the two check valves 20a and 20b on the upstream side and the downstream side of the branch pipe 36, respectively. A pressure detector P3 is also provided between the downstream check valve 20b and the axle box 6. The pressure detector P3 substantially detects the pressure in the axle box 6.

FIG. 4 is a table showing measured values of the pressure gauges P1, P2, and P3 during normal operation (when there is no leak) and when a leak occurs.
In this experiment 1, the pressure values of the pressure gauges P1, P2, and P3 corresponding to changes in the leak amount were measured for the following three patterns.
<Pattern A>: When the pressure of the pressure detector P3 (pressure in the axle box 6) is high (0.04 MPa when the leak amount is 0)
<Pattern B>: When the pressure is intermediate (0.03 MPa)
<Pattern C>: When the pressure is low (0.02 MPa)

  The pressure in the axle box 6 (P3 measurement value) becomes higher as the performance of the sealing device 8 is higher. Therefore, it can be said that the pattern A has the highest sealing performance and the pattern C has the lowest sealing performance. The difference in the sealing performance in this experiment is caused by the dimensional tolerance of the sealing device 8, but in the actual use state, the sealing performance is changed due to the deterioration of the sealing device. Therefore, when this experiment is replaced with an actual use state, it can be considered that the sealing device is deteriorated in the order of patterns A to C.

  FIG. 4 shows the measured values of the pressure gauges P1, P2 and P3 when the solenoid valve 35 is opened and the leak on-off valve 37 is closed, that is, when the leak amount is 0 during normal operation, , B, and C, each pressure gauge P1, when the leak on / off valve 37 is opened and the leak amount is increased stepwise to 5 NL / min, 8 NL / min, and 10 NL / min. The measured values of P2 and P3 are shown in the 2nd to 4th lines, respectively.

  When FIG. 4 is analyzed, for example, when the leak performance does not occur but the seal performance is low (column a of pattern C), the measured value of the pressure gauge P1 is 0.143 MPa, whereas the seal performance is high but the leak amount Is 10 NL / min (pattern A, column b), the measured value of the pressure gauge P1 is 0.154. That is, in the pattern A, the measured value is higher than that in the pattern C although the leak occurs. There is a similar tendency for the measured values of the pressure gauges P2 and P3.

  Therefore, just because the measured values of the pressure gauges P1, P2, and P3 are low, it cannot be determined that a leak has occurred, and vice versa. That is, it can be understood that it is difficult to discriminate between leakage of the oil supply pipe and deterioration of the seal based on the measured values of the pressure gauges P1, P2, and P3 during normal operation.

[Experiment 2]
Next, the present applicant uses the experimental apparatus shown in FIG. 3 to examine the measurement values of the pressure gauge P1 when the solenoid valve 35 is closed and the supply of compressed air is temporarily stopped for the patterns A to C. It was. Furthermore, the measured values of the pressure gauge P1 when the solenoid valve 35 was closed and the leakage on-off valve 37 was opened to generate a leak were examined for the patterns A to C. Then, these two conditions are compared with the time-dependent fluctuation of the measured value of the pressure gauge P1 during normal operation without leakage, and are summarized in the graph of FIG.

  In FIG. 5, the horizontal axis represents the elapsed time since the supply of compressed air was stopped, and the vertical axis represents the measured value of the pressure gauge P1. In FIG. 5, during normal operation with no leak, the measured value of the pressure gauge P1 takes a constant value regardless of the passage of time in any pattern. When the compressed air is stopped in a state where there is no leak (when the inspection operation is performed), the measured value of the pressure gauge P1 decreases with the passage of time in any pattern, although it is slow. However, the pressure of 0.03 MPa or more is maintained even after 30 minutes. When the inspection operation is performed in a state where there is a leak (leak amount: 5 NL / min), the pressure rapidly decreases in any pattern, and the pressure value becomes 0 by 30 seconds. This tends to be substantially the same regardless of the amount of leakage and the length of the oil supply pipe 2c.

  That is, when the compressed air is stopped, the state of pressure fluctuation clearly differs depending on whether or not there is a leak. In determining whether there is a leak, the supply of compressed air is stopped and the pressure of the oil supply pipe 2c is reversed. It can be understood that holding by the stop valves 20a and 20b is effective.

  In FIG. 5, when there is a leak and the compressed air is stopped, the pressure value becomes 0 within 30 seconds. Further, even if the conditions such as the pipe length and the leak amount are changed, the pressure value becomes 0 within approximately one minute. Therefore, in the leak detection method according to the present invention, it is sufficient that the time for stopping the compressed air (time for stopping the normal operation) to detect the leak is about 1 to 2 minutes.

  On the other hand, the delivery of the lubricating oil to the mixer 1 is intermittent, about once every 3 to 5 minutes, and the lubricating oil supply amount is about 1.5 cc / hr for a bearing of about φ200 mm. Therefore, even if the compressed air for about 1 to 2 minutes is stopped, the bearing 3 is not insufficiently lubricated.

  The present invention can be suitably used for lubrication of apparatuses equipped with a large number of rollers, such as rolling mills and continuous casting apparatuses.

It is a lineblock diagram of the whole system of a lubricating oil supply device concerning an embodiment of the present invention. It is side surface sectional drawing of the axle box which is lubrication object. It is a block diagram which shows an experimental apparatus. It is a table | surface which shows an experimental result. It is a graph which shows an experimental result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mixer 3 Bearing 2c-2e Oil supply piping 5b-5e Distribution oil supply piping 21 Pressure detector 20a Upstream check valve (pressure holding valve)
20b Check valve on the downstream side (pressure holding valve)

Claims (3)

In the pneumatic feed type lubricating oil supply device that supplies the lubricating oil to the object to be lubricated through the oil supply pipe by compressed air,
Between the two pressure holding valves and the two pressure holding valves, which are provided in the oil supply pipe with an interval in the supply direction of the lubricating oil and can hold the pressure in the oil supply pipe when the supply of compressed air is stopped And a pressure detector for detecting the pressure of the oil supply pipe.   2. The pneumatic feed type lubricating oil supply device according to claim 1, wherein the pressure holding valve is configured by a check valve that allows compressed air and lubricating oil to flow to an object to be lubricated and prevents reverse flow. 3. . A method for detecting a leak in an oil supply pipe in the pneumatic feeding lubricant supply device according to claim 1, wherein the supply of compressed air is temporarily interrupted, and the pressure of the interrupted oil supply pipe is detected by a pressure detector, A leak detection method, wherein the presence or absence of a leak is determined based on a change in pressure over time.

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