Oil supply unit and extruder

Abstract

An oil supply unit (40) according to one embodiment is provided with: a tank (51) for storing lubricating oil; an oil return passage (58) for returning the lubricating oil from the first object to be lubricated to the tank (51); an oil return passage (65) for returning the lubricating oil from the second object to be lubricated to the tank (51); a tank (63) and a pump (64a) provided in the oil return passage (65); a replenishing oil passage (70) that connects the oil return passage (65) and the tank (63); a valve (71) provided in the replenishment oil passage (70); a monitoring unit (73) that monitors the oil level of the lubricating oil stored in the tank (63); and a control unit (72) that controls the valve (71) on the basis of the monitoring result of the monitoring unit (73). Furthermore, the valve (71) is closed when the oil level of the lubricating oil in the tank (63) is within a predetermined range, and the valve (71) is opened when the oil level of the lubricating oil in the tank (63) is lower than the predetermined range.

Description

Technical Field

[0001] The invention relates to an oil supply unit and an extruder. Background Art

[0002] In order to make the elements constituting the power transmission system and the elements to which the power is transmitted via the power transmission system run smoothly, it is necessary to supply lubricating oil to these elements. Patent document 1 describes an extruder, which has a reducer that transmits the rotational driving force output from the motor to the screw. The reducer of the extruder described in patent document 1 is an example of the above-mentioned element (lubricated object).

[0003] In order to continuously supply lubricating oil to the lubricated object, a pump, a tank, a valve, etc. may be integrated to form an oil supply unit. In addition, when there are a plurality of lubricated objects, an oil supply unit may be prepared for each lubricated object.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-136959 Summary of the invention

[0007] It is desirable to reduce the number of oil supply units relative to the number of lubrication objects and to simplify the configuration of the oil supply units.

[0008] Other problems and new features will become clear from the description of this specification and the accompanying drawings.

[0009] An oil supply unit of one embodiment includes: a first tank storing lubricating oil; a common oil passage connected to the first tank; a first pump, an oil filter, and an oil cooler provided in the common oil passage; a first branch oil passage connecting the common oil passage and a first lubricated object; a second branch oil passage connecting the common oil passage and a second lubricated object; a first oil return passage for returning lubricating oil from the first lubricated object to the first tank; a second oil return passage for returning lubricating oil from the second lubricated object to the first tank; a second tank and a second pump provided in the second oil return passage; a replenishing oil passage connecting the second oil return passage and the second tank; a second valve provided in the replenishing oil passage; a monitoring unit for monitoring the oil level of the lubricating oil stored in the second tank; and a control unit for controlling the second valve based on the monitoring result of the monitoring unit. Moreover, the second valve is closed when the oil level of the lubricating oil in the second tank is within a prescribed range, and the second valve is opened when the oil level of the lubricating oil in the second tank is lower than the prescribed range.

[0010] Effects of the Invention

[0011] According to one embodiment, a single oil supply unit capable of simultaneously supplying lubricating oil to a plurality of lubricated objects can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is an explanatory diagram schematically showing a granulation device.

[0013] Figure 2 This is an explanatory diagram schematically showing an oil supply unit provided in an extruder.

[0014] Figure 3 It is an explanatory diagram showing the flow of lubricating oil when the valve is closed.

[0015] Figure 4 It is an explanatory diagram showing the flow of lubricating oil when the valve is opened.

[0016] Figure 5 This is a flowchart showing an example of a control process of the oil supply unit.

[0017] Figure 6 This is an explanatory diagram schematically showing another extruder. DETAILED DESCRIPTION

[0018] Below, an embodiment will be described in detail based on the accompanying drawings. In addition, in all the drawings referred to for describing the embodiment, the same reference numerals are used for elements and structures having the same function or substantially the same function. In addition, in principle, no repeated description is given for elements and structures that have been described once.

[0019] <Overall composition>

[0020] Figure 1 This is an explanatory diagram schematically showing a granulation device 1A according to one embodiment. Figure 1 The granulation apparatus 1A shown has an extruder 10 and a granulator 30 .

[0021] The extruder 10 includes an extruder body 10a for kneading supplied resin raw materials while heating to produce molten resin, a gear pump 20 for conveying the molten resin to a pelletizer 30, and an oil supply unit 40 for simultaneously supplying lubricating oil to a plurality of lubricated objects.

[0022] The pelletizer 30 includes a die head 31 for molding the molten resin extruded from the extruder 10 into a linear shape (ribbon shape, rope shape), and a cutter 32 for cutting the molten resin molded into a linear shape.

[0023] The lubricating objects to which the lubricating oil is supplied by the oil supply unit 40 of the present embodiment are two reducers provided in the extruder 10. More specifically, one lubricating object is a reducer provided in the extruder body 10a, and the other lubricating object is a reducer provided in the gear pump 20. However, the lubricating objects to which the lubricating oil is supplied simultaneously by the oil supply unit 40 are not limited to the above two reducers.

[0024] <Extruder body>

[0025] The extruder body 10a includes a main motor 11, a speed reducer 12, and a kneading processing unit 13. The main motor 11 is a driving source of the kneading processing unit 13. The rotational driving force output from the main motor 11 is input to the speed reducer 12. The speed reducer 12 reduces the rotation speed of the input rotational driving force and increases the rotational force to output to the kneading processing unit 13. The kneading processing unit 13 includes two screws 14a and 14b driven by the input rotational driving force.

[0026] The screws 14a and 14b of the kneading treatment section 13 knead the molten resin while conveying the molten resin. The screws 14a and 14b are provided inside a barrel (drum) 15 to which the resin raw material is supplied and supported in a rotatable manner. The resin raw material is supplied to the barrel 15 via a raw material hopper 16 provided at one end side of the barrel 15 in the longitudinal direction.

[0027] As described above, the two screws 14a and 14b are rotationally driven by the main motor 11. The screws 14a and 14b are arranged parallel to each other and are rotationally driven at the same time. That is, the extruder 10 has two screws 14a and 14b that are driven simultaneously and parallel to each other, which is generally called a "double-shaft extruder". However, the extruder 10 is not limited to a double-shaft type, and can also be a single-shaft type.

[0028] In the following description, the two screws 14 a and 14 b may be collectively referred to as “screws 14 ”.

[0029] <Gear Pump>

[0030] The gear pump 20 transfers (pressure-feeds) the molten resin delivered from the extruder body 10a (the barrel 15 of the kneading treatment section 13) to the granulator 30. The gear pump 20 includes a motor 21, a speed reducer 22, and a pair of gears 23. The gears 23 are provided in a housing 24 and supported in a rotatable manner. The housing 24 is arranged on a conveying path extending at a right angle to the barrel 15.

[0031] In addition, there is an embodiment in which the housing 24 is arranged on a conveying path parallel to the cartridge 15. From another perspective, there is an embodiment in which the conveying path on which the housing 24 is arranged extends linearly from the cartridge 15.

[0032] The rotational driving force output from the motor 21 is input to the speed reducer 22. The speed reducer 22 reduces the rotation speed of the inputted rotational driving force and increases the rotational force to output to the gear 23. The gear 23 rotates in the housing 24 by the inputted rotational driving force, and extrude the molten resin fed into the housing 24 toward the pelletizer 30.

[0033] <Pelletizer>

[0034] The die head 31 of the pelletizer 30 includes a die base, a die plate, a die plate cover, etc., and has a plurality of nozzles for extruding molten resin. The molten resin fed into the pelletizer 30 by the gear pump 20 is extruded from each nozzle of the die head 31 and formed into a linear shape (ribbon shape, rope shape).

[0035] The cutter 32 provided in the pelletizer 30 continuously cuts the linear molten resin extruded from the die head 31. The cutter 32 is provided on the flow path of the pellet conveying water circulating in the manufacturing system including the pelletizer 1A, and the cutter 32 includes a cutter head driven by a cutter motor 33. The molten resin is extruded from the die head 31 into the pellet conveying water, and is cut into a predetermined length by the cutter head. As a result, resin pellets of a predetermined size (length and thickness) are produced.

[0036] The above method of cutting the molten resin in the pellet conveying water (water) is sometimes referred to as "underwater cutting". In addition, depending on the characteristics of the resin raw material (particularly the melting point), there are cases where the resin pellets are produced without circulating the pellet conveying water. In this case, the molten resin extruded from the die head 31 is extruded into the air and cut. In this way, the method of cutting the molten resin in the air is sometimes referred to as "thermal cutting".

[0037] <Composition of the oil supply unit>

[0038] Figure 2 1 is an explanatory diagram schematically showing an oil supply unit 40 provided in the extruder 10 of the present embodiment. The oil supply unit 40 supplies lubricating oil to both the speed reducer 12 provided in the extruder body 10a and the speed reducer 22 provided in the gear pump 20.

[0039] The oil supply unit 40 includes two tanks 51 and 63 , and an oil passage, a pump, and the like for circulating lubricating oil between the tanks 51 and 63 and the speed reducers 12 and 22 .

[0040] More specifically, the oil supply unit 40 has a common oil passage 52 connected to the tank 51. A pump 53a, an oil cooler 54, an oil filter 56, and an oil filter 62 are provided on the common oil passage 52. The common oil passage 52 is divided into a branch oil passage 55 connected to the speed reducer 12 and a branch oil passage 61 connected to the speed reducer 22 in front of the oil filters 56 and 62 (on the downstream side).

[0041] A valve 57 is provided in the branch oil passage 55 connected to the speed reducer 12. The valve 57 is a manual valve. The opening of the valve 57 is set to supply a predetermined amount of lubricating oil to the speed reducer 12 and the speed reducer 22, and the opening of the valve 57 can be adjusted as needed.

[0042] The oil supply unit 40 further includes an oil return passage 58 for returning the lubricating oil supplied to the speed reducer 12 via the common oil passage 52 and the branch oil passage 55 to the tank 51 , and an oil return passage 65 for returning the lubricating oil supplied to the speed reducer 22 via the common oil passage 52 and the branch oil passage 61 to the tank 51 .

[0043] The tank 63 is provided on the oil return passage 65, and a pump 64a is provided on the oil return passage 65 on the downstream side of the tank 63. However, the lubricating oil supplied to the reducer 22 flows into the tank 63 by gravity (self-weight). Therefore, there is a case where the section on the upstream side of the tank 63 in the oil return passage 65 is referred to as the "connection passage 65a" to distinguish it from other sections. In addition, unless otherwise specified, the "oil return passage 65" in the following description refers to the section on the downstream side of the tank 63 (the section other than the connection passage 65a).

[0044] The oil supply unit 40 also has a replenishing oil passage 70 connecting the oil return passage 65 and the tank 63. In addition, the oil supply unit 40 has a valve 71 provided in the replenishing oil passage 70, a control unit 72 for controlling the valve 71, and a monitoring unit 73 for monitoring the oil level of the lubricating oil stored in the tank 63. In the following description, the control unit 72 may be referred to as a "valve control unit 72".

[0045] The valve 71 is a solenoid valve. The control unit 72 controls the valve 71 based on the monitoring result of the monitoring unit 73. The monitoring unit 73 is a level transmitter that measures the oil level without contacting the lubricating oil in the tank 63. More specifically, the monitoring unit 73 measures the oil level based on the time from when an ultrasonic wave or electromagnetic wave is emitted toward the oil surface to when the ultrasonic wave or electromagnetic wave returns.

[0046] However, the monitoring unit 73 is not limited to a non-contact type such as a liquid level transmitter, and the monitoring unit 73 may be replaced by a contact type such as a floating type or a pressure type.

[0047] The oil supply unit 40 further includes a backup oil passage 59 connecting the tank 51 and the common oil passage 52, and a discharge oil passage 66 connecting the tank 63 and the oil return passage 65. The backup oil passage 59 is provided with a pump 53b, and the discharge oil passage 66 is provided with a pump 64b.

[0048] One end side of the backup oil passage 59 merges with the common oil passage 52 between the pump 53a and the oil cooler 54. Therefore, no matter which of the pumps 53a and 53b is operated, the lubricating oil in the tank 51 is sent to the common oil passage 52 and flows to the downstream side through the oil cooler 54. When the pump 53a stops operating for some reason, the pump 53b will operate instead of the pump 53a. That is, the pump 53b is a backup pump.

[0049] Among the components of the oil supply unit 40, at least the tank 51, the common oil passage 52, the pump 53a, the pump 53b, the oil cooler 54, the oil filter 56, the valve 57, the backup oil passage 59, the oil filter 62, the tank 63, the pump 64a, the pump 64b, the discharge oil passage 66, the replenishment oil passage 70, the valve 71, the valve control unit 72 and the monitoring unit 73 are provided on a common base member (e.g., a pad). In addition, the branch oil passage 55, the oil return passage 58, the branch oil passage 61 and a part of the oil return passage 65 that cross the oil supply unit 40 and the speed reducers 12 and 22 are also provided on the above-mentioned base member.

[0050] That is, the oil supply unit 40 is a single oil supply unit capable of simultaneously supplying lubricating oil to two or more lubricating objects (reducers 12, 22). From another perspective, in the extruder 10 having the oil supply unit 40, even if the oil supply unit for the reducer 12 and the oil supply unit for the reducer 22 are not separately provided, lubricating oil can be simultaneously supplied to these reducers 12, 22.

[0051] All or part of the oil passages may be formed using piping components such as metal pipes, resin pipes, and resin hoses. However, it is not necessary to form all the oil passages using the same piping components. In other words, the oil passages may also be formed using a plurality of piping components of different types.

[0052] The pump is an electric pump, and the pump is controlled by a control unit 80. In the following description, the control unit 80 may be referred to as a "pump control unit 80." The pump control unit 80 controls at least the operation of the pump 64b based on the monitoring result of the monitoring unit 73.

[0053] In addition, there is an embodiment in which an integrated control unit is provided for integrated control of the entire oil supply unit 40 including the valve control unit 72 and the pump control unit 80, and an embodiment in which an integrated control unit is provided for integrated control of the entire extruder 10 including the oil supply unit 40. In such an embodiment, the valve control unit 72 controls the valve 71 under the control of the integrated control unit, and the pump control unit 80 controls the pump 64b and other pumps under the control of the integrated control unit.

[0054] <Lubricating oil flow>

[0055] In the oil supply unit 40, the flow of lubricating oil when the valve 71 on the replenishing oil passage 70 is closed is different from the flow of lubricating oil when the valve 71 is opened. In addition, as described above, the valve 57 on the branch oil passage 55 is always open at a preset opening.

[0056] Figure 3 It is an explanatory diagram showing the flow of lubricating oil when the valve 71 is closed. Figure 4 It is an explanatory diagram showing the flow of lubricating oil when the valve 71 is opened.

[0057] Reference Figure 3 If pump 53a and pump 64a are operated when valve 57 is in an open state and valve 71 is in a closed state, lubricating oil is supplied from tank 51 to reducer 12 via common oil passage 52 and branch oil passage 55. At the same time, lubricating oil is supplied from tank 51 to reducer 22 via common oil passage 52 and branch oil passage 61.

[0058] The lubricating oil supplied to the speed reducer 12 lubricates the bearings, gears, and the like in the speed reducer 12 , and then returns to the tank 51 through the oil return passage 58 .

[0059] On the other hand, the lubricating oil supplied to the reducer 22 lubricates the bearings, gears, etc. in the reducer 22, and then returns to the tank 51 via the oil return passage 65. More specifically, the lubricating oil after passing through the reducer 22 flows into the tank 63 via the oil return passage 65 (connecting passage 65a) and is temporarily stored. Thereafter, the lubricating oil is sucked out of the tank 63 by the pump 64a and sent to the oil return passage 65. That is, the lubricating oil supplied to the reducer 22 returns to the tank 51 via the tank 63 and the pump 64a.

[0060] Reference Figure 4 If the pump 53a and the pump 64a are operated when the valve 57 and the valve 71 are in the open state, the lubricating oil supplied to the speed reducer 12 returns to the tank 51 through the same path as described above.

[0061] On the other hand, at least a portion of the lubricating oil supplied to the speed reducer 22 does not return to the tank 51 but returns to the tank 63. More specifically, if the valve 71 on the replenishing oil passage 70 connecting the oil return passage 65 and the tank 63 is opened, the lubricating oil sucked from the tank 63 by the pump 64a and sent to the oil return passage 65 returns to the tank 63 via the replenishing oil passage 70.

[0062] <Operation of the oil supply unit>

[0063] Figure 51 is a flowchart showing an example of the control process of the oil supply unit 40. When the control process starts, step S1 is implemented. In step S1, the valve control unit 72 determines the oil level of the lubricating oil in the tank 63. More specifically, the valve control unit 72 determines whether the oil level of the lubricating oil in the tank 63 is between the lower limit value and the upper limit value of the prescribed range based on the monitoring result of the monitoring unit 73.

[0064] If it is determined in step S1 that the oil level of the lubricating oil is lower than the specified range, the process proceeds to step S2. More specifically, if the valve control unit 72 determines that the oil level of the lubricating oil is lower than the lower limit of the specified range, the process proceeds to step S2. In step S2, the valve 71 is opened under the control of the valve control unit 72. Specifically, power is supplied to the solenoid coil of the valve 71 to open the valve 71.

[0065] Next, the process proceeds to step S3. In step S3, the valve control unit 72 determines the oil level of the lubricating oil in the tank 63 again. More specifically, the valve control unit 72 determines whether the oil level of the lubricating oil in the tank 63 has returned to within a specified range based on the monitoring result of the monitoring unit 73. In other words, the valve control unit 72 determines whether the oil level of the lubricating oil in the tank 63 is between the lower limit value and the upper limit value of the specified range.

[0066] If the valve 71 is opened in step S2, the following occurs: Figure 4 As shown in FIG. 1 , the oil level of the lubricating oil in the tank 63 gradually rises. That is, the amount of lubricating oil in the tank 63 gradually increases.

[0067] If it is determined in step S3 that the oil level of the lubricating oil in the tank 63 has returned to within the predetermined range, the process proceeds to step S4 .

[0068] In step S4, the valve 71 is closed under the control of the valve control unit 72. Specifically, the power supplied to the solenoid coil of the valve 71 is cut off, and the valve 71 is closed.

[0069] On the other hand, if it is determined in step S1 that the oil level of the lubricating oil is higher than the upper limit of the prescribed range, the process proceeds to step S5 instead of step S2. In step S5, the pump 64b is operated under the control of the pump control unit 80. In addition, since step S2 is not performed, the valve 71 is not opened and remains closed.

[0070] If the pump 64b is running in step S5, Figure 3In addition to the flow of lubricating oil shown in FIG. 1 , the flow of lubricating oil from the tank 63 to the oil return passage 65 via the discharge oil passage 66 occurs. That is, the lubricating oil is sucked out of the tank 63 by the two pumps 64a and 64b. In addition, since the valve 71 is in the closed state, the lubricating oil does not return to the tank 63. As a result, the oil level of the lubricating oil in the tank 63 gradually decreases. That is, the amount of lubricating oil in the tank 63 gradually decreases.

[0071] After the oil level of the lubricating oil in the tank 63 returns to within the prescribed range, the pump 64b is manually stopped. However, there is also an embodiment in which the pump 64b is automatically stopped if the oil level of the lubricating oil in the tank 63 returns to within the prescribed range. In addition, after stopping the pump 64b, the opening of the valve 57 is adjusted as needed.

[0072] One of the reasons why the oil level of the lubricating oil is determined to be lower than the lower limit of the specified range in step S1 is that the oil filter 62 is clogged. If the oil filter 62 is clogged, the amount of lubricating oil supplied to the reducer 22 via the branch oil passage 61 will decrease. As a result, the amount of lubricating oil passing through the reducer 22 and flowing into the tank 63 will also decrease. As a result, the amount of lubricating oil in the tank 63 gradually decreases. From another perspective, the balance between the oil storage amount of the tank 51 and the oil storage amount of the tank 63 is destroyed.

[0073] In this embodiment, if the oil storage amount of the tank 63 falls below a predetermined range due to any reason including the above reasons, the tank 63 will automatically be replenished with lubricating oil. Therefore, the balance between the oil storage amount of the tank 51 and the oil storage amount of the tank 63 will not be disturbed.

[0074] The invention completed by the inventor of the present application is specifically described above based on the embodiments and examples, but the present invention is not limited to the above embodiments or examples, and various changes can be made within the scope of the main purpose. For example, the multiple lubrication objects to which the lubricating oil is simultaneously supplied by the oil supply unit are not limited to the reducer equipped with the extruder body and the reducer equipped with the gear pump.

[0075] Figure 6 This is an explanatory diagram schematically showing an extruder 10 according to another embodiment. Figure 6 The extruder 10 shown in the figure includes two or more extruder bodies and an oil supply unit for simultaneously supplying lubricating oil to these extruder bodies. More specifically, it includes two extruder bodies 10A and 10B and an oil supply unit 40 for simultaneously supplying lubricating oil to these extruder bodies 10A and 10B.

[0076] The extruder bodies 10A and 10B have the same or substantially the same structure as the extruder 10a of the above-mentioned embodiment. However, there are cases where the extruder bodies 10A and 10B are arranged in parallel, and there are also cases where the extruder bodies 10A and 10B are arranged in series. For example, there is also a case where the extruder body 10A constitutes a first-stage extrusion mechanism and the extruder body 10B constitutes a second-stage extrusion mechanism.

[0077] The oil supply unit 40 supplies lubricating oil to the lubricating objects respectively provided in the extruder bodies 10A and 10B. For example, the oil supply unit 40 simultaneously supplies lubricating oil to the main motor reducers respectively provided in the extruder bodies 10A and 10B. Alternatively, the oil supply unit 40 simultaneously supplies lubricating oil to other reducers respectively provided in the extruder bodies 10A and 10B.

[0078] The granulator 30 of the above embodiment can be replaced with a film forming machine. In this case, the extruder 10 and the film forming machine constitute a film forming device.

[0079] The valve 71 of the above embodiment is not limited to a solenoid valve. In addition, the valve 57 is not limited to a manual valve. The position of the oil cooler 54 can be appropriately changed. However, in the above embodiment in which the oil cooler 54 is arranged on the common oil passage 52, the lubricating oil circulating in the unit is cooled by one oil cooler 54. From another perspective, the number of required oil coolers is reduced. From another perspective, the number of parts requiring maintenance is reduced.

[0080] The housing of the lubricated object can be used as the tank of the oil supply unit. For example, the housing of the speed reducer 12 of the above embodiment can also serve as the tank 51, and the housing of the speed reducer 22 can also serve as the tank 63.

[0081] Description of Reference Numerals

[0082] 1A: granulator, 10: extruder, 10a, 10A, 10B: extruder body, 11: main motor, 12: reducer, 13: kneading processing unit, 14, 14a, 14b: screw, 15: barrel, 16: raw material hopper, 20: gear pump, 21: motor, 22: reducer, 23: gear, 24: housing, 30: granulator, 31: die head, 32: cutter, 33: cutter motor, 40: oil supply unit, 51: tank, 52: Common oil passage, 53a, 53b: Pump, 54: Oil cooler, 55: Branch oil passage, 56: Oil filter, 57: Valve, 58: Oil return passage, 59: Backup oil passage, 61: Branch oil passage, 62: Oil filter, 63: Tank, 64a, 64b: Pump, 65: Oil return passage, 65a: Connecting passage, 66: Discharge oil passage, 70: Refill oil passage, 71: Valve, 72: Control unit (valve control unit), 73: Monitoring unit, 80: Control unit (pump control unit).

Claims

1. An oil supply unit, characterized in that: Lubricating oil is supplied to a plurality of lubricated objects simultaneously, and the oil supply unit comprises: The first tank for storing lubricating oil; a common oil passage connected to the first tank; A first pump, an oil filter and an oil cooler provided in the common oil passage; a first branch oil passage connecting the common oil passage and a first lubrication object; a second branch oil passage connecting the common oil passage and a second lubrication object; Returning lubricating oil from the first lubricated object to the first oil return passage of the first tank; Returning lubricating oil from the second lubricated object to the second oil return passage of the first tank; a second tank and a second pump provided in the second oil return passage; an oil replenishment passage connecting the second oil return passage and the second tank; a second valve provided in the replenishing oil passage; a monitoring unit for monitoring the oil level of the lubricating oil stored in the second tank; and a control unit that controls the second valve based on a monitoring result of the monitoring unit, The second valve is closed when the oil level of the lubricating oil in the second tank is within a prescribed range, and the second valve is opened when the oil level of the lubricating oil in the second tank is lower than the prescribed range.

2. An extruder, characterized in that: Equipped with extruder body, gear pump and oil supply unit, The extruder body has: a first electric motor; a first speed reducer to which the rotational driving force output from the first electric motor is input; and a screw driven by a rotational driving force output from the first speed reducer; The gear pump has: A second electric motor; a second speed reducer to which the rotational driving force output from the second electric motor is input; a gear driven by the rotational driving force output from the second speed reducer to extrude the molten resin, The oil supply unit comprises: The first tank for storing lubricating oil; a common oil passage connected to the first tank; A first pump, an oil filter and an oil cooler provided in the common oil passage; A first branch oil passage connecting the common oil passage and the first reducer; A second branch oil passage connecting the common oil passage and the second reducer; Returning lubricating oil from the first reducer to the first oil return passage of the first tank; Returning lubricating oil from the second reducer to the second oil return passage of the first tank; a second tank and a second pump provided in the second oil return passage; an oil replenishment passage connecting the second oil return passage and the second tank; a second valve provided in the replenishing oil passage; a monitoring unit for monitoring the oil level of the lubricating oil stored in the second tank; and a control unit that controls the second valve based on a monitoring result of the monitoring unit, The second valve is closed when the oil level of the lubricating oil in the second tank is within a prescribed range, and the second valve is opened when the oil level of the lubricating oil in the second tank is lower than the prescribed range.

3. An extruder, characterized in that: The invention is provided with two or more extruder bodies and an oil supply unit for simultaneously supplying lubricating oil to the extruder bodies. The oil supply unit comprises: The first tank for storing lubricating oil; a common oil passage connected to the first tank; A first pump, an oil filter and an oil cooler provided in the common oil passage; A first branch oil passage connecting the common oil passage and the first extruder body; A second branch oil passage connecting the common oil passage and the second extruder body; Returning lubricating oil from the first extruder body to the first oil return passage of the first tank; Returning lubricating oil from the second extruder body to the second oil return passage of the first tank; a second tank and a second pump provided in the second oil return passage; an oil replenishment passage connecting the second oil return passage and the second tank; a second valve provided in the replenishing oil passage; a monitoring unit for monitoring the oil level of the lubricating oil stored in the second tank; and a control unit that controls the second valve based on a monitoring result of the monitoring unit, The second valve is closed when the oil level of the lubricating oil in the second tank is within a prescribed range, and the second valve is opened when the oil level of the lubricating oil in the second tank is lower than the prescribed range.

4. The extruder according to claim 2 or 3, characterized in that The oil supply unit includes a discharge oil passage connecting the second tank and the second oil return passage, and a third pump provided in the discharge oil passage. If the oil level of the lubricating oil in the second tank is higher than the predetermined range, the third pump is operated with the second valve closed.

5. The extruder according to claim 4, characterized in that The oil supply unit includes a backup oil passage connecting the first tank and the common oil passage, and a fourth pump provided in the backup oil passage.

6. The extruder according to claim 5, characterized in that The monitoring unit is a level transmitter that measures the oil level without contacting the lubricating oil stored in the second tank.

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