Oil supply amount control system

Abstract

To provide an oil supply amount control system which can reduce electric power consumption of an oil supply pump and can restrain deterioration of lubricating oil.SOLUTION: An oil supply amount control system according to an embodiment includes a main device and an inverter device. The main device generates, on the basis of a first speed command for a main unit motor, a second speed command for an oil supply pump which supplies lubricating oil to a bearing of the main unit motor, and outputs the generated command to the inverter device. The inverter device drives the oil supply pump on the basis of the second speed command. A value of the second speed command is larger as a value of the first speed command is larger. The main device starts the oil supply pump in a time shorter than the main unit motor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an oil supply amount control system that automatically controls the amount of oil supplied to bearings of a main electric motor of a rolling mill. [Background technology]

[0002] The main motors of steel rolling equipment often use sliding bearings that require oiling from a bearing oiler. The faster the main motor, the greater the amount of oil that needs to be supplied to the bearings. The amount of oil supplied from the bearing oiler to the main motor is often set to the amount required when the main motor is running at its maximum speed.

[0003] The lubricating oil supplied to the bearings of the main electric motor is supplied by an oil supply pump that is driven by a commercial power source and whose speed cannot be controlled (for example, Patent Document 1, etc.).

[0004] The main motor operates at various speeds depending on the properties of the steel plate being rolled, such as the material and rolling volume. Meanwhile, the oil supply pump, which cannot be controlled in speed, is operated, for example, at maximum speed to ensure the oil supply amount when the main motor is operated at maximum speed. As a result, the oil supply pump tends to operate in a way that supplies more oil than is actually required to the bearings of the main motor, resulting in increased power loss in the oil supply pump. Furthermore, supplying more lubricating oil to the main motor than is actually required can lead to problems such as deterioration of the lubricating oil. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 52-65303 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of an embodiment of the present invention is to provide an oil supply amount control system that can reduce the power consumption of an oil supply pump and suppress deterioration of lubricating oil. [Means for solving the problem]

[0007] An oil supply amount control system according to an embodiment of the present invention includes a main unit that generates a second speed command, which is a speed command for an oil supply pump that supplies lubricating oil to bearings of a main electric motor, based on a first speed command, which is a speed command supplied to a main electric motor drive unit that controls the speed of the main electric motor that drives the rolls of a rolling mill, and an inverter unit that controls the oil supply pump based on the second speed command generated by the main unit. The main unit generates the second speed command, which has a larger value as the value of the first speed command increases, so that the rolled material starts the oil supply pump earlier than the start time of the main electric motor. [Effects of the Invention]

[0008] According to an embodiment of the present invention, it is possible to provide an oil supply amount control system that can reduce the power consumption of an oil supply pump and suppress deterioration of lubricating oil. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic block diagram illustrating a fuel supply amount control system according to an embodiment; [Figure 2] FIG. 3 is a schematic operational waveform diagram for explaining the operation of the fuel supply amount control system. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0011] FIG. 1 is a schematic block diagram illustrating a fuel supply amount control system according to an embodiment. As shown in Fig. 1, the oil supply amount control system 100 is communicatively connected to a main electric motor drive device 10 for a rolling mill. The oil supply amount control system 100 is also electrically connected to an oil supply pump 3. In Fig. 1, solid arrows indicate the direction in which lubricating oil flows, and dashed arrows indicate electrical signals.

[0012] The main electric motor drive device 10 outputs, for example, a first speed command N1, which is a speed command for the main electric motor 1 transmitted from a higher-level control device, to the oil supply amount control system 100. The oil supply amount control system 100 generates a second speed command N2, which is a speed command for the oil supply pump 3, based on the first speed command N1, and drives the oil supply pump 3 at a speed according to the second speed command N2.

[0013] In the steel rolling facility to which the oil supply amount control system 100 is applied, a main electric motor 1 is installed, and the main electric motor 1 is provided with a bearing 2 that rotatably supports the rotor of the main electric motor 1. The steel rolling facility is also provided with an oil supply system that supplies lubricating oil to the bearing 2. The oil supply system consists of an oil supply pump 3, an oil tank 4, and piping through which the lubricating oil flows. The output port of the oil supply pump 3 is connected to one of the pipes, which is connected to the bearing 2. Another pipe is provided to discharge the lubricating oil supplied to the bearing 2, and this separate pipe is connected to the oil tank 4.

[0014] An oil supply pump 3 driven by the oil supply amount control system 100 draws up lubricating oil from an oil tank 4 and supplies the lubricating oil via a pipe to the bearing 2. The lubricating oil supplied to the bearing 2 is collected in the oil tank 4 via another pipe.

[0015] The oil supply amount control system 100 drives the oil supply pump 3 in accordance with the second speed command N2 generated based on the first speed command N1 of the main electric motor 1, so that the lubricating oil is supplied to the bearing 2 at a flow rate corresponding to the second speed command N2.

[0016] More specifically, the oil supply amount control system 100 is set so that the amount of lubricant oil required for the bearing 2 increases as the value of the first speed command N1 increases, and so that the value of the second speed command N2 increases as the value of the first speed command N1 increases. In other words, the oil supply amount control system 100 increases the value of the second speed command N2 as the value of the first speed command N1 increases, thereby supplying a larger amount of lubricant oil to the bearing 2. Furthermore, the oil supply amount control system 100 decreases the value of the second speed command N2 as the value of the first speed command N1 decreases, thereby supplying a smaller amount of lubricant oil to the bearing 2.

[0017] In the example of FIG. 1, a temperature sensor 5 is provided on the bearing 2. The temperature sensor 5 is provided on the bearing 2 so as to measure the temperature of the lubricating oil supplied to the bearing 2. The temperature sensor 5 outputs data on the detected lubricating oil temperature T1 to the oil supply amount control system 100. The oil supply amount control system 100 corrects the second speed command N2 based on the value of the lubricating oil temperature T1. For example, the oil supply amount control system 100 has a threshold value T1th for the lubricating oil temperature T1, and when the lubricating oil temperature T1 exceeds the threshold value T1th, the oil supply amount control system 100 sets the value of the second speed command N2 to a maximum value. The oil supply amount control system 100 operates the oil supply pump 3 at the maximum speed and increases the amount of oil supply until the lubricating oil temperature T1 becomes equal to or lower than the threshold value T1th.

[0018] The configuration of the fuel supply amount control system 100 according to the embodiment will be described. The fuel supply amount control system 100 according to the embodiment includes a main device 20 and an inverter device 30 for a fuel supply pump.

[0019] The master device 20 is communicatively connected to the main electric motor drive device 10. The master device 20 inputs a first speed command N1 for the main electric motor 1 via the main electric motor drive device 10. The master device 20 generates a second speed command N2 for the oil supply pump 3 based on the input first speed command N1 and outputs it to the inverter device 30. Note that the master device 20 is not limited to the above, and may directly acquire the first speed command N1 from a higher-level control device that outputs the first speed command N1, or may acquire it via another control device or the like.

[0020] The relationship between the value of the first speed command N1 and the value of the second speed command N2 can be set based on the relationship between the amount of lubricating oil supply q1 required for the bearing 2 and the amount of oil supply q2 based on the speed characteristics of the oil supply pump 3.

[0021] More specifically, the supply amount q1 of lubricating oil required for the bearing 2 is set to an appropriate value depending on the speed n1 of the main electric motor 1, as shown in the following equation (1).

[0022] q1=F(n1) (1)

[0023] Here, F(n1) is a function of the lubricant supply amount q1 relative to the speed n1, which can be measured in advance by actual measurement or the like. The function F(x) can be determined depending on the structure and material of the bearing, the components of the lubricant, etc. The lubricant supply amount q1 is expressed in units of flow rate (for example, [m 3 / seconds).

[0024] The speed characteristic of the oil supply pump 3 can be expressed as the following equation (2) in terms of the relationship between the oil supply amount q2 and the speed n2 of the oil supply pump 3.

[0025] n2=G(q2) (2)

[0026] Here, G(q2) is a function that represents the relationship between the fuel pump speed n2 and the fuel supply amount q2, and is the speed characteristic of the fuel pump 3. The speed characteristic of the fuel pump 3 can be obtained, for example, by using the characteristic provided by a supplier such as the manufacturer of the fuel pump, or by actual measurement, etc.

[0027] The speed n1 of the main motor 1 follows the first speed command N1 through feedback control by the main motor drive device 10, and in the steady state, if the speed n1 coincides with the first speed command N1, then equation (1) can be expressed as the following equation (1'). q1=F1(N1) (1')

[0028] Furthermore, assuming that the speed n2 of the oil supply pump 3 is equal to the second speed command N2 in the steady state, it can be expressed by the following equation (2').

[0029] N2=G(q2) (2')

[0030] By using equations (1') and (2'), the second speed command N2 for the oil supply pump 3 can be generated for any first speed command N1. More specifically, by assuming that the lubricant supply rate q1 is equal to the oil supply rate q2 due to the oil supply rate q2 in equations (1') and (2'), the second speed command N2 can be calculated based on the first speed command N1. Generally, F(x) and G(x) are monotonically increasing functions, and the larger the value of the first speed command N1, the larger the value of the second speed command N2, and the larger the oil supply rate q2 can be supplied to the bearing 2. Note that the above equations (1) to (2') hold when the speed and flow rate are in a steady state, and may not hold when the electric motor or pump is accelerating or decelerating.

[0031] The temperature sensor 5 provided on the bearing 2 is connected to the master unit 20. The master unit 20 compares the acquired lubricant temperature T1 with a preset threshold value T1th related to the lubricant temperature T1. When the temperature T1 exceeds the threshold value T1th, the master unit 20 sets the value of the second speed command N2 to a maximum value regardless of the value of the first speed command N1, and outputs the maximum value to the inverter unit 30. When the temperature T1 is equal to or lower than the threshold value T1th, the master unit 20 generates a value of the second speed command N2 based on the value of the first speed command N1 and outputs the value to the inverter unit 30. The correction of the value of the second speed command N2 related to the temperature T1 by the master unit 20 is not limited to the above. Multiple threshold values ​​may be set to switch the speed in multiple stages depending on the temperature, or the speed may be changed continuously depending on the temperature.

[0032] The operation of the fuel supply amount control system 100 according to the embodiment will be described with reference to operational waveforms. FIG. 2 is a schematic operational waveform diagram for explaining the operation of the fuel supply amount control system.

[0033] The top diagram in Figure 2 shows the time variation of the value of the first speed command N1 and the actual speed n1 of the main electric motor 1. In the diagram, the value of the first speed command N1 is represented by a dashed line, and the speed n1 is represented by a solid line. This diagram also shows the target value N1s of the first speed command N1.

[0034] The second diagram in Figure 2 shows the change over time in the lubricant supply rate q1. This diagram also shows the target value q1s of the lubricant supply rate q1. As explained in relation to equations (1) to (2'), the speed of the oil supply pump 3 is controlled so that the oil supply rate q2 of the oil supply pump 3 matches the lubricant supply rate q1.

[0035] The bottom diagram in Fig. 2 shows the time variation of the value of the second speed command N2 and the actual speed n2 of the fuel supply pump 3. The value of the second speed command N2 is represented by a dashed line, and the speed n2 is represented by a solid line. This diagram also shows the target value N2s of the value of the second speed command N2.

[0036] As shown in Fig. 2, at time t0, the main motor drive device 10 outputs a first speed command N1 to the main device 20. The main motor drive device 10 drives the main motor 1, and the main motor 1 starts in accordance with the output torque of the main motor drive device 10, the moment of inertia of the rolls of the rolling mill, etc.

[0037] In the period up to time t0, the amount of lubricating oil supplied is set to the minimum value q1m, and in order to supply this, the main device 20 sets the value of the second speed command N2 in the inverter device 30 to the minimum value N2m, thereby ensuring the minimum amount of lubricating oil supplied.

[0038] During the period from time t0 to time t1, the speed n2 of the oil supply pump 3 reaches the target value N2s. This period is the startup time of the oil supply pump 3. The supply amount q1 of lubricating oil gradually increases during the startup time of the oil supply pump 3, and reaches the target value q1s of the supply amount q1.

[0039] Meanwhile, the speed n1 of the main electric motor 1 reaches the target value N1s in the period from time t0 to time t2. This period is the start-up time of the main electric motor 1. In other words, the oil supply pump 3 starts up in a time shorter than the start-up time of the main electric motor 1. This allows the supply amount q1 of lubricating oil supplied to the bearings 2 to reach the desired amount before the main electric motor 1 reaches the target value N1s, making it possible to ensure stable operation of the main electric motor 1.

[0040] In order to make the startup time of the oil supply pump 3 shorter than the startup time of the main electric motor 1, for example, during the startup time, the main device 20 sets the value of the second speed command N2 to the maximum value and overdrives the oil supply pump 3. Alternatively, the main device 20 may use a tracking signal that tracks the position of the leading edge of the rolled material to generate the second speed command N2 at a timing earlier than time t0, regardless of the first speed command N1, and output it to the inverter device 30.

[0041] During the period from time t2 to time t7, the speed n1 of the main electric motor 1 is controlled to a substantially constant value, following the value of the first speed command N1. During the period from time t2 to time t7, the value of the second speed command N2 of the oil supply pump 3 is constant at the target value N2s. The oil supply pump 3 is operated at a constant speed substantially equal to the target value N2s, and the oil supply amount q2 is a substantially constant value that matches the lubricating oil supply amount q1.

[0042] During the period from time t2 to time t7, the material to be rolled enters and is discharged from the rolling mill. During the period from time t3 to time t4, the material to be rolled is engaged in the rolling mill, so the speed n1 transiently decreases. Furthermore, during the period from time t5 to time t6, the material to be rolled leaves the rolling mill, so the speed n1 transiently increases. The main unit 20 generates a second speed command N2 based on the first speed command N1, and the inverter unit 30 drives the oil supply pump 3 based on the generated second speed command N2. Therefore, the oil supply amount q2 of the oil supply pump 3 is not affected by transient speed fluctuations of the main electric motor 1, and the desired supply amount q1 (= q2) can be supplied to the bearing 2.

[0043] At time t7, the main electric motor drive device 10 outputs a first speed command N1 with a value of 0 to the main device 20. As the value of the first speed command N1 becomes 0, the main electric motor drive device 10 starts deceleration and stops driving the main electric motor 1 at time t8.

[0044] At time t7, even though the value of the first speed command N1 becomes 0, the main device 20 continues to output the target value N2s to the inverter device 30 until time t8. The oil supply pump 3 maintains the supply of the target value q1s of the lubricating oil supply amount q1, which is the target value of the oil supply amount q2, until time t8. A sufficient length is set for the period between time t7 and time t8.

[0045] The lubricant supply amount q1 is maintained at the target value q1s until time t8, and then decreases, and in the example of Figure 2, reaches the minimum value q1m at time t9 when the oil supply pump 3 reaches the minimum maintaining speed N2m.

[0046] Although not described in the example of FIG. 2, when the lubricant temperature T1 detected by the temperature sensor 5 reaches a predetermined threshold value T1th, the master device 20 sets, for example, the value of the second speed command N2 to the maximum value, regardless of the target value N1s of the first speed command N1. This allows the oil supply pump 3 to supply lubricant to the bearing 2 at the maximum amount of oil. By supplying low-temperature lubricant to the bearing 2, the temperature of the bearing 2 decreases, and the lubricant temperature T1 also decreases. This makes it possible to suppress increases in the temperature of the bearing 2 and the lubricant temperature T1, thereby extending their lifespans.

[0047] In the above description, the target value reached during the start-up of the oil supply pump 3 is set to a constant target value N1s based on the value of the first speed command N1 during constant speed control of the main electric motor 1. However, this is not limiting. In a rolling plant where the main electric motor 1 is installed, the oil supply system may use very long piping to supply and circulate lubricating oil. The piping length may reach several tens of meters. In such long piping, the oil supply pump 3 may need to be operated at a sufficient speed to ensure a sufficient supply amount during start-up. In such cases, a value exceeding the target value N2s, e.g., a maximum value, may be temporarily set during the start-up of the oil supply pump 3, and the lubricating oil may be quickly supplied to the desired flow rate by overdrive. Alternatively, instead of or in addition to overdrive, the oil supply pump 3 may be started prior to the start-up of the main electric motor 1 using a tracking signal from the leading edge of the rolled material, thereby enabling a more reliable increase in the amount of lubricating oil.

[0048] The effects of the fuel supply amount control system 100 according to the embodiment will be described. In the fuel supply amount control system 100 according to the embodiment, the fuel supply pump 3 is driven by the second speed command N2 generated based on the value of the first speed command N1 that drives the main electric motor 1. Therefore, even if the speed setting of the main electric motor 1 differs depending on the type of steel, for example, the power loss of the fuel supply pump 3 can be reduced compared to when the fuel supply pump 3 is driven at maximum speed.

[0049] In the oil supply amount control system 100 according to this embodiment, the oil supply pump 3 is driven by the second speed command N2 generated based on the value of the first speed command N1 that drives the main electric motor 1, so that lubricating oil can be supplied to the bearings 2 at a supply amount that corresponds to the speed of the main electric motor 1. Therefore, when the main electric motor 1 is operated at a high speed, the amount of lubricating oil supplied is large, and when the main electric motor 1 is operated at a slow speed, the amount of lubricating oil supplied can be reduced, so that deterioration of the lubricating oil can be suppressed and the life of the lubricating oil can be extended.

[0050] In the oil supply amount control system 100 according to the embodiment, the amount of lubricating oil supplied can be minimized while the main electric motor 1 is stopped. Therefore, during periods when rolling is stopped, the speed of the oil supply pump 3 can be minimized, and power loss can be further reduced. Similarly, deterioration of the lubricating oil can be further suppressed.

[0051] In the oil supply amount control system 100 according to the embodiment, the speed of the oil supply pump 3 is appropriately set according to the temperature T1 of the lubricating oil in the bearing 2, thereby preventing an excessive rise in the temperature of the lubricating oil and further extending the life of the lubricating oil.

[0052] In this way, it is possible to realize an oil supply amount control system that can reduce the power consumption of the oil supply pump and suppress deterioration of the lubricating oil.

[0053] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0054] 1...Main motor, 2...Bearing, 3...Oil supply pump, 4...Oil tank, 5...Temperature sensor, 10...Main motor drive device, 20...Main device, 30...Inverter device, 100...Oil supply amount control system

Claims

1. a main unit that generates a second speed command, which is a speed command for an oil supply pump that supplies lubricating oil to bearings of the main electric motor, based on a first speed command, which is a speed command supplied to a main electric motor drive unit that controls the speed of the main electric motor that drives the rolls of the rolling mill; an inverter device that controls the fuel pump based on the second speed command generated by the main device; Equipped with The main device generates the second speed command having a larger value as the value of the first speed command increases, and the rolled material starts the oil supply pump earlier than the start-up time of the main electric motor.

2. 2. The fuel supply amount control system according to claim 1, wherein the master device sets the value of the second speed command to a maximum value when the fuel supply pump is started.

3. 2. The fuel supply amount control system according to claim 1, wherein the master device sets the second speed command to a value greater than 0 at a timing before the first speed command transitions to a set value greater than 0.

4. 2. The fuel supply amount control system according to claim 1, wherein the main device sets the value of the second speed command to 0 after the value of the first speed command becomes 0.

5. An oil supply amount control system as described in any one of claims 1 to 4, wherein the main device sets the value of the second speed command to a maximum value when the temperature of the lubricating oil in the bearing detected by a temperature sensor provided in the bearing is above a predetermined threshold value.

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