Power consumption detection system and power consumption detection method for screw machinery

Abstract

The power consumption of the screw machine is detected by calculation without using an energy meter. [Solution] In a power consumption detection system 1 for an extruder 100 comprising a screw 10 that rotates around an axis to transport material toward the tip, a barrel 20 into which a cylinder 21 into which the screw 10 is inserted is formed, a motor unit 50 that rotates the screw 10, and a controller 60 that controls the operation of the motor unit 50, the controller 60 detects the energy efficiency η of the motor unit 50. E The power consumption is calculated using the value of [this value].

Description

[Technical Field]

[0001] The present invention relates to a power consumption detection system for screw machinery and a method for detecting power consumption for screw machinery. [Background technology]

[0002] Patent Document 1 discloses a twin-screw extruder (screw machine) for producing pellets from supplied material, comprising a material supply unit, a melting and kneading unit, and a discharge unit. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-161860 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, in recent years, when using screw machinery, it has become necessary to monitor power consumption from an environmental protection perspective. Normally, an energy meter is used to detect the power consumption of screw machinery, but in order to simplify the equipment, there has been a need to detect power consumption without using an energy meter.

[0005] However, in screw-driven machinery, the load fluctuates greatly depending on the state of the material supplied to the cylinder, resulting in large fluctuations in the power consumption of the motor that rotates the screw. Therefore, it has been difficult to detect the power consumption of screw-driven machinery without using an energy meter.

[0006] This invention has been made in view of the above-mentioned problems, and aims to detect the power consumption of a screw machine by calculation without using an energy meter. [Means for solving the problem]

[0007] According to an aspect of the present invention, in a power consumption detection system for a screw machine including a screw that rotates around an axis to convey a material to the tip side, a barrel in which a cylinder into which the screw is inserted is formed, a motor unit that rotationally drives the screw, and a controller that controls the operation of the motor unit, the controller calculates the power consumption using the value of the energy efficiency of the motor unit.

Advantages of the Invention

[0008] According to this aspect, by using the value of the energy efficiency of the motor unit, the power consumption can be accurately calculated. Therefore, the power consumption of the screw machine can be detected by calculation without using a wattmeter.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a front view of a screw machine to which the power consumption detection system according to an embodiment of the present invention is applied, and is a schematic view showing a barrel in cross section. [Figure 2] FIG. 2 is a schematic view showing a cross section taken along line II-II in FIG. 1. [Figure 3] FIG. 3 is a configuration diagram of the power consumption detection system. [Figure 4] FIG. 4 is a flowchart for explaining power consumption detection control. [Figure 5] FIG. 5 is a diagram for explaining the value of energy efficiency with respect to the rotational speed and output torque of the motor shaft of the motor unit. [Figure 6] FIG. 6 is a diagram for explaining the detection results of the elapsed time and integrated power when the power consumption detection system is applied.

Embodiments of the Invention

[0010] Hereinafter, the power consumption detection system 1 according to an embodiment of the present invention will be described with reference to the drawings. In each drawing, for convenience of explanation, the scale of each component is appropriately changed and is not necessarily strictly shown.

[0011] First, the overall configuration of the extruder 100, which is a screw machine to which the power consumption detection system 1 is applied, will be described with reference to Figures 1 and 2. Figure 1 is a front view of the extruder 100, and is a schematic diagram showing the barrel 20 in cross-section. Figure 2 is a schematic diagram showing the II-II cross-section in Figure 1.

[0012] As shown in Figures 1 and 2, the extruder 100 comprises a pair of screws 10a and 10b, a barrel 20, a feeding device 30, a motor unit 50, and a controller 60. The extruder 100 is a so-called twin-screw compounding extruder equipped with a pair of screws 10a and 10b. However, the extruder 100 is not limited to a twin-screw compounding extruder; for example, it may be a single-screw or multi-screw extruder with three or more screws.

[0013] The extruder 100 is an extruder that kneads granular or powdery material supplied into the cylinder 21 of the barrel 20 while conveying it with screws 10a and 10b, and then extrudes the kneaded material from the discharge port 23 of the barrel 20 to form a shape. In the following, the direction in which the rotation axes of screws 10a and 10b extend, that is, the direction in which the material is conveyed, will be referred to as the "conveying direction" or "axial direction".

[0014] The barrel 20 has a cylinder 21 into which a pair of screws 10a and 10b are inserted. The barrel 20 is formed by connecting a plurality of barrel units 20a along one direction. The barrel 20 is a cylindrical member formed to extend in one direction, with a pair of through holes 21a and 21b (see Figure 2) formed along its longitudinal direction (axial direction). The pair of through holes 21a and 21b are in communication with each other, and the cylinder 21 is formed by the pair of through holes 21a and 21b.

[0015] The supply device 30 has a supply hole 22 and a hopper 32.

[0016] The supply hole 22 is formed in the barrel unit 20a at one end of the barrel 20 in the longitudinal direction. The supply hole 22 is formed as an opening in the cylinder 21. The supply hole 22 is a hole for supplying material into the cylinder 21 at the base end. The material is supplied from a feeder (not shown) through a hopper 32 to the supply hole 22.

[0017] A discharge port 23 is formed in the barrel unit 20a at the other longitudinal end of the barrel 20, opening into the cylinder 21 for discharging the mixture produced from the molten and kneaded material. Hereinafter, the side of the cylinder 21 with the supply hole 22 (right side in Figure 1) will also be referred to as the "upstream" or "base end" of the cylinder 21, and the side with the discharge port 23 (left side in Figure 1) will also be referred to as the "downstream" or "tip end" of the cylinder 21. The material supplied into the cylinder 21 through the supply hole 22 is transported downstream by screws 10a and 10b and discharged out of the barrel 20 through the discharge port 23.

[0018] The barrel 20 is further provided with a plurality of vent holes (not shown) for discharging and removing gas from inside the cylinder 21 to the outside of the cylinder 21, a heating device (not shown) for heating the barrel 20, a cooling device (not shown) for cooling the barrel 20, and a temperature sensor (not shown) for detecting the temperature of the barrel 20.

[0019] As shown in Figure 2, a pair of screws 10a and 10b have similar shapes and extend parallel to each other, and are inserted into the cylinder 21 of the barrel 20 in a meshed state. The pair of screws 10a and 10b are rotated in the same direction around their respective central axes (axislines) by the motor unit 50 (see Figure 1) via the reduction unit 55. In other words, the pair of screws 10a and 10b rotate synchronously with each other. Hereafter, the pair of screws 10a and 10b will be collectively referred to simply as "screw 10," and their specific configuration will be described.

[0020] As shown in Figure 1, the screw 10 is a shaft member provided along the longitudinal direction of the barrel 20, extending from its base end, which is connected to the motor unit 50, to its tip. The base end of the screw 10 is located upstream of the cylinder 21, and the tip of the screw 10 is located downstream of the cylinder 21. The screw 10 is rotationally driven around its axis by the motor unit 50, and conveys the material supplied at the base end to the tip end.

[0021] The screw 10 has a first transfer section 11a, a second transfer section 11b, and a third transfer section 11c that transfer the material in the cylinder 21 downstream, a first kneading section 13 and a second kneading section 14 that knead the material in the cylinder 21, and an end section 15 that protrudes to the outside of the barrel 20. In this embodiment, the first transfer section 11a, the first kneading section 13, the second transfer section 11b, the second kneading section 14, and the third transfer section 11c are provided in that order from upstream to downstream of the cylinder 21. In the following, when the first transfer section 11a, the second transfer section 11b, and the third transfer section 11c are not distinguished, they will be collectively referred to as "transfer section 11".

[0022] The transfer section 11 has spiral flights 12 (screw blades) on its outer circumference. The material supplied to the cylinder 21 from the supply hole 22 is transferred downstream toward the first kneading section 13 by the first transfer section 11a of the rotating screw 10. In other words, the supply hole 22 is formed in the barrel 20 so as to face the first transfer section 11a.

[0023] The second transfer unit 11b is located between the first kneading unit 13 and the second kneading unit 14, and transports the material kneaded and melted by the first kneading unit 13 toward the second kneading unit 14.

[0024] The third transfer unit 11c transports the material, which has been further kneaded and melted by the second kneading unit 14, toward the discharge port 23.

[0025] The first kneading section 13 is composed of a plurality of discs 13a arranged in the longitudinal direction (the axial direction of the screw 10). The discs 13a are kneading discs with a substantially elliptical shape.

[0026] As disk 13a, a forward-feed disk having a twist in the same direction as the twist of the flight 12 of the transfer unit 11, a reverse-feed disk having a twist in the opposite direction to the twist of the flight 12 of the transfer unit 11, and a neutral disk without twist can be used.

[0027] Similarly, the second kneading section 14 is composed of a plurality of discs 14a arranged in the longitudinal direction (the axial direction of the screw 10). The discs 14a are substantially elliptical kneading discs. The second kneading section 14 is located relatively downstream of the first kneading section 13 (towards the tip of the screw 10). That is, the second kneading section 14 is spaced apart from the first kneading section 13 in the axial direction of the screw 10.

[0028] As disk 14a, a forward-feed disk having a twist in the same direction as the twist of the flight 12 of the transfer unit 11, a reverse-feed disk having a twist in the opposite direction to the twist of the flight 12 of the transfer unit 11, and a neutral disk without twist can be used.

[0029] The forward-feed disc, like the transfer unit 11, transports the material from upstream to downstream of the cylinder 21 (in other words, from the base end to the tip end of the screw 10). The reverse-feed disc transports the material in the opposite direction to the transfer unit 11 and the forward-feed disc. Therefore, the reverse-feed disc functions to brake the material flow that is transported from upstream to downstream. The neutral disc has no twist and therefore only has the ability to knead the material and does not have the ability to transport the material.

[0030] The end 15 of the screw 10 is connected to the first transfer section 11a on the side opposite to the first kneading section 13 in the axial direction of the screw 10. The end 15 passes through the barrel unit 20a at the upstream end of the barrel 20 and is connected to the motor shaft 54, which serves as the output shaft of the motor unit 50, via a reduction section 55, which will be described later.

[0031] The motor unit 50 rotates a pair of screws 10a and 10b within the cylinder 21. The operation of the motor unit 50 is controlled by the controller 60. The motor shaft 54 ​​of the motor unit 50 is connected to a reduction gear 55, and the rotation of the motor shaft 54 ​​is transmitted to the pair of screws 10a and 10b via the reduction gear 55. As a result, the pair of screws 10a and 10b are rotationally driven by the motor unit 50.

[0032] The reduction gear unit 55 reduces the rotation of the motor shaft 54 ​​of the motor unit 50 by a gear mechanism (not shown) composed of multiple gears and transmits it to a pair of screws 10a and 10b. The end 15 of the screw 10 is connected to the reduction gear unit 55. Since a known configuration can be used for the gear mechanism of the reduction gear unit 55, a detailed explanation and illustration are omitted.

[0033] The controller 60 controls the operation of the motor unit 50. Specifically, the controller 60 controls the rotational speed N [rpm] and output torque T [N·m] of the motor shaft 54 ​​in the motor unit 50. The controller 60 is composed of a microcomputer equipped with a CPU, RAM, ROM, input / output interface, etc. The controller 60 performs various processes by having the CPU read and execute a program stored in the ROM. The controller 60 can also be composed of multiple microcomputers.

[0034] Next, the power consumption detection system 1 will be described with reference to Figure 3. Figure 3 is a configuration diagram of the power consumption detection system 1.

[0035] The power consumption detection system 1 detects the power consumption of the extruder 100. In this case, the power consumption detection system 1 detects the power consumption of the motor unit 50 in the extruder 100. The power consumption detection system 1 may also detect the power consumption of other units of the extruder 100, such as a heating device that heats the barrel 20.

[0036] The power consumption detection system 1 includes a controller 60. Here, power consumption detection control is performed by a controller other than the controller 60, which controls the operation of the motor unit 50 provided in the extruder 100.

[0037] As shown in Figure 3, the motor unit 50 is supplied with power from the power supply unit 2. The motor unit 50 includes a motor 51 that rotates the screw 10 and an inverter device 52 that drives the motor 51. The motor 51 has a pulse generator 51a that generates an electrical signal corresponding to the rotational speed N [rpm].

[0038] The controller 60 controls the energy efficiency η of the motor unit 50. E The power consumption is calculated using the [%] value. The controller 60 also operates using power supplied from the power supply unit 2.

[0039] Energy efficiency η E [%] represents a value corresponding to the rotational speed N [rpm] and output torque T [N·m] of the motor shaft 54 ​​of the motor unit 50. Energy efficiency η E [%] represents the overall energy efficiency of the motor 51 and the inverter device 52 combined.

[0040] Next, power consumption detection control by the power consumption detection system 1 will be explained with reference to Figures 4 to 6. Figure 4 is a flowchart illustrating the power consumption detection control. Figure 5 shows the energy efficiency η of the motor shaft 54 ​​of the motor unit 50 with respect to the rotational speed N [rpm] and output torque T [N·m]. E This figure explains the value of [%]. Figure 6 shows the elapsed time t [sec] and integrated power P when the power consumption detection system 1 is applied. I This diagram explains the detection results for [kWh].

[0041] The controller 60 repeatedly executes the flow shown in Figure 4, for example, at intervals of 10 [ms], to calculate the power consumption of the extruder 100, which changes moment by moment.

[0042] In step S101, the controller 60 detects the rotational speed N [rpm] of the motor shaft 54. The rotational speed N [rpm] of the motor shaft 54 is obtained from the feedback value of the pulse generator 51a from the motor 51 to the inverter device 52.

[0043] In step S102, the controller 60 detects the output torque T [N·m] of the motor 51. The output torque T [N·m] is obtained from the torque output value from the inverter device 52 to the motor 51.

[0044] In step S103, the controller 60 obtains the energy efficiency η E [%] from the rotational speed N [rpm] and the output torque T [N·m]. This will be specifically described below.

[0045] The following equation (1) is a general formula for obtaining the power consumption P M of the motor 51. In equation (1), P M is the power consumption [kW] of the motor 51, T is the output torque T [N·m] of the motor 51, and N is the rotational speed N [rpm] of the motor shaft 54.

[0046]

Equation

[0047] The following equation (2) is a formula for obtaining the energy efficiency η INV [%] of the inverter device 52, and equation (3) is a formula for obtaining the energy efficiency η M [%] of the motor 51. In equations (2) and (3), P INV(IN) is the power [W] input from the power supply device 2 to the inverter device 52, P INV(OUT) is the power [W] output from the inverter device 52, P M(IN) is the power [W] supplied to the motor 51, P M(OUT) is the power [W] output from the motor 51 (see FIG. 3). As shown in FIG. 3, P INV(IN)This is the power consumption supplied from the power supply unit 2 and consumed by the motor unit 50, P INV(OUT) and P M(IN) These are the same value.

[0048]

number

[0049]

number

[0050] Equation (4) below is derived from equations (2) and (3) and represents the energy efficiency η of the motor unit 50, which combines the motor 51 and the inverter device 52. E This is the formula for calculating [%].

[0051]

number

[0052] Equation (5) below is derived from equations (1) and (4) and represents the power P input to the inverter device 52. INV(IN) This is the formula for finding [the value].

[0053]

number

[0054] Here, as shown in Figure 5, when the output torque T [N·m] of the motor 51 decreases, the ratio of loss to output increases, so the energy efficiency η of the motor 51 decreases. M [%] decreases. Also, even when the output torque T [N·m] is constant, if the rotational speed N [rpm] (output frequency) of the motor shaft 54 ​​decreases, the energy efficiency η of the motor 51 decreases. M [%] decreases. Therefore, in the power consumption detection system 1, P, which is the power consumption of the motor unit 50, is calculated as shown in equation (6) below. INV(IN)When determining the energy efficiency η, the rotational speed N [rpm] of the motor shaft 54 ​​and the output torque T [N·m] of the motor 51 are used. E The value [%] can be set as a parameter. Note that equation (6) is derived from equations (4) and (5).

[0055]

number

[0056] Returning to Figure 4, in step S104, the controller 60 controls the energy efficiency η E The power consumption of the motor unit 50 is calculated using the value of [%] (Equation (6)).

[0057] In Figure 6, the horizontal axis represents the elapsed time t [sec] since the start of operation of the extruder 100, and the vertical axis represents the power consumption P. INV(IN) The cumulative value P I [kWh]. Also, in Figure 6, the integrated value of power consumption measured using an energy meter is shown as a dashed line for comparison, and the energy efficiency η E The dashed line shows the cumulative power consumption calculated using a typical value (90[%] in this case) for [%], and the cumulative power consumption P calculated by applying the power consumption detection system 1 according to this embodiment. I [kWh] is shown by a solid line.

[0058] As shown in Figure 6, the energy efficiency η E When [%] is calculated using a general value, it deviates from the cumulative power consumption measured using an energy meter over time. In contrast, when the power consumption detection system 1 according to this embodiment is applied to the calculation, it does not deviate from the cumulative power consumption measured using an energy meter over time, and shows a value close to the cumulative power consumption measured using an energy meter.

[0059] Thus, the energy efficiency η of the motor unit 50 EBy using the [%] value, power consumption can be calculated with high accuracy. Therefore, the power consumption of the extruder 100 can be detected by calculation without using an energy meter.

[0060] At this time, the energy efficiency η changes according to the rotational speed N [rpm] and output torque T [N·m] of the motor shaft 54. E Using the [%] value can improve the accuracy of power consumption calculations.

[0061] The effects and advantages of this embodiment will be described below.

[0062] In a power consumption detection system 1 for an extruder 100, which includes a screw 10 that rotates around an axis to transport material toward the tip, a barrel 20 into which a cylinder 21 into which the screw 10 is inserted is formed, a motor unit 50 that rotationally drives the screw 10, and a controller 60 that controls the operation of the motor unit 50, the controller 60 detects the energy efficiency η of the motor unit 50. E The power consumption is calculated using the value of [%].

[0063] Furthermore, in a method for detecting the power consumption of an extruder 100 comprising a screw 10 that rotates around an axis to transport material toward the tip, a barrel 20 into which a cylinder 21 into which the screw 10 is inserted is formed, a motor unit 50 that rotationally drives the screw 10, and a controller 60 that controls the operation of the motor unit 50, the energy efficiency η of the motor unit 50 E The power consumption is calculated using the value of [%].

[0064] According to these configurations, the energy efficiency η of the motor unit 50 E By using the [%] value, power consumption can be calculated with high accuracy. Therefore, the power consumption of the extruder 100 can be detected by calculation without using an energy meter.

[0065] Furthermore, energy efficiency η E[%] represents a value corresponding to the rotational speed N [rpm] and output torque T [N·m] of the motor shaft 54 ​​of the motor unit 50.

[0066] Furthermore, the controller 60 detects the rotational speed N [rpm] and output torque T [N·m] of the motor shaft 54, and calculates the energy efficiency η of the motor unit 50 from the rotational speed N and output torque T. E [%] is obtained, and energy efficiency η E The power consumption is calculated using the value of [this value].

[0067] According to these configurations, the energy efficiency η changes depending on the rotational speed N [rpm] and output torque T [N·m] of the motor shaft 54. E Using the [%] value can improve the accuracy of power consumption calculations.

[0068] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. [Explanation of symbols]

[0069] 100 Extruders (Screw Machines) 1. Power Consumption Detection System 10 screws 10a screw 10b screw 20 barrels 21 Cylinders 50 Motor Units 51 Motor 51a Pulse Generator 52 Inverter device 54 Motor shaft (output shaft) 60 Controllers η E Energy efficiency

Claims

1. A power consumption detection system for a screw machine comprising: a screw that rotates around an axis to transport material toward the tip; a barrel into which a cylinder into which the screw is inserted is formed; a motor unit that rotates the screw; and a controller that controls the operation of the motor unit, The controller calculates the power consumption using the energy efficiency value of the motor unit. A power consumption detection system for screw machinery.

2. A power consumption detection system for a screw machine according to claim 1, The energy efficiency is a value that corresponds to the rotational speed and output torque of the output shaft of the motor unit. A power consumption detection system for screw machinery.

3. A power consumption detection system for a screw machine according to claim 2, The controller detects the rotational speed and output torque of the output shaft, obtains the energy efficiency of the motor unit from the rotational speed and output torque, and calculates the power consumption using the value of the energy efficiency. A power consumption detection system for screw machinery.

4. A power consumption detection system for a screw machine according to claim 2 or 3, The motor unit is A motor that rotates the screw, An inverter device that drives the motor, It has, The aforementioned energy efficiency is the overall energy efficiency of the motor and the inverter device combined. A power consumption detection system for screw machinery.

5. A power consumption detection system for a screw machine according to claim 4, The output torque is determined from the torque output value from the inverter device to the motor. A power consumption detection system for screw machinery.

6. A power consumption detection system for a screw machine according to claim 4, The motor has a pulse generator that generates an electrical signal corresponding to the rotational speed, The rotational speed is determined from the feedback value of the pulse generator from the motor to the inverter device. A power consumption detection system for screw machinery.

7. A method for detecting the power consumption of a screw machine comprising a screw that rotates around an axis to transport material toward the tip, a barrel into which a cylinder into which the screw is inserted is formed, and a motor unit that rotates the screw, The power consumption is calculated using the energy efficiency value of the motor unit. A method for detecting the power consumption of a screw machine.

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