WO2022244599A1 - 押出成形機の混練状態検出装置及び混練状態検出方法 - Google Patents
押出成形機の混練状態検出装置及び混練状態検出方法 Download PDFInfo
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- WO2022244599A1 WO2022244599A1 PCT/JP2022/018717 JP2022018717W WO2022244599A1 WO 2022244599 A1 WO2022244599 A1 WO 2022244599A1 JP 2022018717 W JP2022018717 W JP 2022018717W WO 2022244599 A1 WO2022244599 A1 WO 2022244599A1
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- Prior art keywords
- kneading state
- kneading
- extruder
- raw material
- state detection
- Prior art date
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- 238000004898 kneading Methods 0.000 title claims abstract description 166
- 238000001514 detection method Methods 0.000 title claims abstract description 67
- 239000002994 raw material Substances 0.000 claims abstract description 111
- 230000008859 change Effects 0.000 claims abstract description 62
- 239000000654 additive Substances 0.000 claims abstract description 18
- 230000000996 additive effect Effects 0.000 claims abstract description 13
- 239000003365 glass fiber Substances 0.000 claims description 61
- 239000011347 resin Substances 0.000 claims description 61
- 229920005989 resin Polymers 0.000 claims description 61
- 238000001228 spectrum Methods 0.000 claims description 25
- 238000004364 calculation method Methods 0.000 claims description 13
- 230000007423 decrease Effects 0.000 claims description 6
- 238000012545 processing Methods 0.000 description 23
- 238000010586 diagram Methods 0.000 description 19
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- 238000000034 method Methods 0.000 description 11
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
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- 230000000644 propagated effect Effects 0.000 description 2
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- 238000010008 shearing Methods 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000004397 blinking Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
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- 239000000470 constituent Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
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- 230000001747 exhibiting effect Effects 0.000 description 1
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- 238000009499 grossing Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 239000004973 liquid crystal related substance Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
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- 229910001220 stainless steel Inorganic materials 0.000 description 1
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- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
- B29B7/58—Component parts, details or accessories; Auxiliary operations
- B29B7/72—Measuring, controlling or regulating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
- B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
- B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
- B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
- B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
- B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
- B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
- B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
- B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
- B29B7/482—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws provided with screw parts in addition to other mixing parts, e.g. paddles, gears, discs
- B29B7/483—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws provided with screw parts in addition to other mixing parts, e.g. paddles, gears, discs the other mixing parts being discs perpendicular to the screw axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B7/00—Mixing; Kneading
- B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
- B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
- B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
- B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
- B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
- B29B7/488—Parts, e.g. casings, sealings; Accessories, e.g. flow controlling or throttling devices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
- B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/92—Measuring, controlling or regulating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/14—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object using acoustic emission techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4409—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison
- G01N29/4427—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by comparison with stored values, e.g. threshold values
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4472—Mathematical theories or simulation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/449—Statistical methods not provided for in G01N29/4409, e.g. averaging, smoothing and interpolation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/46—Processing the detected response signal, e.g. electronic circuits specially adapted therefor by spectral analysis, e.g. Fourier analysis or wavelet analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/023—Solids
- G01N2291/0231—Composite or layered materials
Definitions
- the present invention relates to a kneading state detection device and a kneading state detection method for an extruder.
- the kneading state of raw materials by an extruder can be measured by, for example, the elapsed time from the start of kneading, the measured value of a pressure sensor that measures the internal pressure of the extruder, and the temperature sensor that measures the internal temperature of the extruder. value, the torque fluctuation value of the motor that drives the extruder, the current value that flows through the motor, and the like (see Patent Documents 1, 2, and 3).
- a kneading state detection device for an extruder is provided when an extruder for kneading a raw material or kneading a raw material and an additive is in an operating state.
- an acquisition unit that acquires the output of an AE sensor installed in the housing of the extruder, and a comparison between the intensity change of the output of the AE sensor over a predetermined time and a threshold value acquired by the acquisition unit, and a determination unit that determines the kneading state of the raw material or the raw material and the additive.
- the kneading state detection device and kneading state detection method for an extruder according to the present invention can reliably detect the kneading state of raw materials in real time.
- FIG. 1 is an explanatory diagram of acoustic emissions.
- FIG. 2 is a schematic structural diagram of the AE sensor.
- FIG. 3 is a schematic structural diagram showing an example of a kneading state detection device for a twin-screw extruder.
- FIG. 4 is a cross-sectional view of the output shaft of a twin-screw extruder.
- FIG. 5 is a hardware block diagram showing an example of the hardware configuration of the kneading state detection device of the twin-screw extruder according to the embodiment.
- FIG. 6 is a diagram showing an example of the results of frequency analysis of AE waves acquired by the AE wave analysis device.
- FIG. 1 is an explanatory diagram of acoustic emissions.
- FIG. 2 is a schematic structural diagram of the AE sensor.
- FIG. 3 is a schematic structural diagram showing an example of a kneading state detection device for a twin-screw extruder.
- FIG. 7 is a diagram showing an example of temporal changes in the integrated value of the power spectrum of the AE wave acquired by the AE wave analyzer from 60 kHz to 80 kHz.
- FIG. 8 is a diagram for explaining a method for determining whether the broken state of the glass fiber has stabilized based on the waveform of the AE wave acquired by the AE wave analyzer.
- FIG. 9 is a functional block diagram showing an example of the functional configuration of the kneading state detection device of the twin-screw extruder according to the embodiment.
- FIG. 10 is a flow chart showing an example of the flow of processing performed by the kneading state detection device.
- FIG. 11 shows an example of the time change of the integrated value of the power spectrum when the screw rotation speed is changed while the twin-screw extruder is continuously operated and the resin raw material and the glass fiber are sufficiently kneaded.
- FIG. 4 is a diagram showing;
- FIG. 12 shows an example of the time change of the integrated value of the power spectrum when the resin raw material and the glass fiber are sufficiently kneaded in a state where the twin-screw extruder is continuously operated and the input flow rate of the resin raw material is changed. It is a figure which shows.
- FIG. 13 shows an example of the time change of the integrated value of the power spectrum when the twin-screw extruder is continuously operated and the resin raw material and the glass fiber are sufficiently kneaded, and the flow rate of the glass fiber is changed. It is a figure which shows.
- AE acoustic emission
- the frequency band of the AE wave is said to be about several tens of kHz to several MHz, and has a frequency band that cannot be detected by a general vibration sensor or acceleration sensor. Therefore, a dedicated AE sensor is used to detect AE waves. Details of the AE sensor will be described later.
- the reinforcing material is mixed into the resin raw material, but the material to be mixed is not limited to the reinforcing material. For example, even when additives such as talc, calcium carbonate, and magnesium carbonate are mixed, the following description is similarly applied.
- Fig. 1 is an explanatory diagram of acoustic emissions.
- FIG. 1 for example, at a point P inside the twin-screw extruder 30, when the resin pellets are crushed or the reinforcing material is broken, an AE wave W is generated.
- the AE wave W spreads radially from the point P and penetrates inside the housing of the twin-screw extruder 30 . Then, the AE waves W that have entered the housing propagate inside the housing of the twin-screw extruder 30 .
- the AE wave W propagated inside the housing of the twin-screw extruder 30 is detected by the AE sensor 20 installed on the surface of the housing of the twin-screw extruder 30 . Then, the AE sensor 20 outputs a detection signal D. Since the detection signal D is a signal representing vibration, it is an AC signal having positive and negative values as shown in FIG. However, since it is difficult to handle the detection signal D (AE wave W) as it is when various calculations are performed, it is common to treat the negative portion of the detection signal D as a half-wave rectified waveform.
- RMS Root Mean Square
- the propagation speed of the AE wave W differs between the longitudinal wave and the transverse wave (the longitudinal wave is faster than the transverse wave), but considering the size (propagation distance) of the solid material Q, the difference can be ignored.
- AE waves W detected within a predetermined period of time are analyzed as measurement signals without distinction between longitudinal waves and transverse waves.
- Fig. 2 is a schematic structural diagram of the AE sensor.
- the AE sensor 20 is enclosed in a shield case 20a and installed in contact with the surface of a housing (barrel) 32 of a twin-screw extruder 30, which is a detection target. It is installed at the tip of a rod 21 (wave guide).
- the waveguide rod 21 is made of ceramic or stainless steel, and transmits the AE wave W transmitted inside the housing 32 to the AE sensor 20 .
- a heater 39 for melting the resin pellets is attached to the surface of the housing 32 of the twin-screw extruder 30, and the temperature rises to about 200°C, so the AE sensor 20 cannot be installed directly on the housing 32. . Therefore, the AE sensor 20 is installed via the waveguide rod 21 .
- a magnet 22 is installed at the tip of the waveguide rod 21 on the side of the twin-screw extruder 30 , and the waveguide rod 21 avoids the position of the heater 39 by the magnet 22 and is located in the housing of the twin-screw extruder 30 . It is fixed to the surface of body 32 .
- the end of the waveguide rod 21 on the side of the twin-screw extruder 30 may be fixed to the surface of the housing 32 by screwing.
- the other end side of the waveguide rod 21 is connected to the wave receiving surface 20b of the AE sensor 20.
- the wave receiving surface 20b of the AE sensor 20 may be coated with grease.
- a deposited film 20c of copper or the like is formed on the wave receiving surface 20b.
- a piezoelectric element 20d made of lead zirconate titanate (PZT) or the like is installed on the deposited film 20c. 20 d of piezoelectric elements receive the AE wave W which propagated the inside of the waveguide rod 21 via the receiving surface 20b, and output the electric signal according to the said AE wave W concerned.
- PZT lead zirconate titanate
- An electric signal output by the piezoelectric element 20d is output as a detection signal D via the deposited film 20e and the connector 20f. Since the detection signal D is weak, a preamplifier (not shown in FIG. 2) is installed inside the AE sensor 20 in order to suppress the influence of noise contamination. can be output with
- a first embodiment of the present disclosure is an example of a kneading state detection device for a twin-screw extruder that determines the kneading state of glass fibers mixed in a resin raw material.
- the twin-screw extruder is an example, and the present embodiment is applicable to general extruders such as single-screw extruders and multi-screw extruders.
- FIG. 3 is a schematic structural diagram showing an example of a kneading state detection device for a twin-screw extruder.
- FIG. 4 is a cross-sectional view of the output shaft of a twin-screw extruder.
- the twin-screw extruder 30 is driven according to the output of the gear box 40. More specifically, the gear box 40 decelerates the rotational driving force of the motor 24 to rotationally drive the two output shafts 42 of the twin-screw extruder 30 in the same direction. A screw 44 and a kneading disk 46, which will be described later, are installed on the outer periphery of the output shaft 42. As the output shaft 42 rotates, the resin material (resin pellets) fed into the twin-screw extruder 30 is plasticized. The strength of the resin raw material is improved by mixing and kneading a reinforcing material such as glass fiber into the resin raw material.
- the twin-screw extruder 30 is an example of an extruder in the present disclosure.
- the two output shafts 42 are arranged parallel to each other along the Y-axis, separated by a certain axial distance C along the X-axis, inside the cylindrical housing (barrel) 32 of the twin-screw extruder 30. placed in
- FIG. 4(a) is an AA cross-sectional view of the twin-screw extruder 30.
- the output shaft 42 is inserted into a spline hole 43 formed in the screw 44 .
- the output shaft 42 rotates the screw 44 inside the insertion hole 34 by meshing with the spline hole 43 .
- FIG. 4(b) is a BB cross-sectional view of the twin-screw extruder 30.
- the output shaft 42 is inserted into a spline hole 43 formed in a kneading disk 46.
- the output shaft 42 rotates the kneading disk 46 inside the insertion hole 34 by meshing with the spline hole 43 .
- the screw 44 rotates at a speed of, for example, 300 revolutions per minute, thereby extruding the melted resin raw material and the glass fiber mixed in the resin raw material introduced into the twin-screw extruder 30 into the twin-screw extruder. 30 downstream. Further, the screws 44 provided on the respective output shafts 42 are engaged with each other to transport the melted resin raw material downstream. Further, the glass fibers mixed in the resin raw material are subjected to a large shearing force and broken when passing through the meshing portion of the screw 44 provided on each output shaft 42 .
- the kneading disc 46 has a structure in which a plurality of elliptical discs are arranged in a direction perpendicular to the output shaft 42 and adjacent discs are shifted along the output shaft 42 .
- the adjacent discs By arranging the adjacent discs in a staggered manner, the flow of the resin raw material is divided between the discs, thereby promoting the kneading of the conveyed resin raw material and the glass fiber mixed in the resin raw material. That is, the kneading disk 46 is heated by the heater 39 and imparts shearing energy to the resin raw material conveyed by the screw 44, thereby completely melting the resin raw material.
- Insertion holes 34 into which the respective output shafts 42 are inserted are provided inside the housing 32 .
- the insertion hole 34 is a hole provided along the longitudinal direction of the housing 32 and has a shape in which portions of cylinders are overlapped. As a result, the screw 44 and the kneading disk 46 can be inserted into the insertion hole 34 while they are engaged with each other.
- a supply port 36a is provided for introducing the pellet-shaped resin raw material to be kneaded and the powder-shaped filler material into the insertion hole 34. It is Then, a reinforcing material such as glass fiber is introduced from a supply port 36b provided in the side feeder 37 on the downstream side of the supply port 36a.
- a reinforcing material such as glass fiber is introduced from a supply port 36b provided in the side feeder 37 on the downstream side of the supply port 36a.
- the direction in which the material is supplied by the supply ports 36a and 36b is not limited to the example shown in FIG.
- a discharge port 38 for discharging the material kneaded while passing through the insertion hole 34 is provided on the other end side of the housing 32 in the longitudinal direction. Further, a heater 39 is provided on the outer periphery of the housing 32 to heat the resin raw material introduced into the insertion hole 34 by heating the housing 32 .
- the output shaft 42 of the twin-screw extruder 30 has two screws 44 and one kneading disk 46.
- the number of screws 44 and kneading disks 46 is It is not limited to the example shown in FIG.
- the kneading discs 46 may be installed at a plurality of locations to knead the resin raw material and the glass fiber.
- the AE sensor 20 is installed via a waveguide rod 21 on the surface of the housing 32 of the twin-screw extruder 30 on the downstream side of the supply port 36b. Then, the output of the AE sensor 20 is input to the AE wave analyzer 10 .
- the AE sensor 20 and the AE wave analyzer 10 constitute a kneading state detector 50 .
- the AE sensor 20 is installed near the kneading disk 46, which is the main source of the AE waves W during the kneading of the raw materials, as shown in FIG. It is desirable to
- the configuration and function of the AE sensor 20 are as described above.
- the AE wave analyzer 10 analyzes the frequency component of the AE wave W output by the AE sensor 20 to determine whether the breaking state of the glass fibers fed into the twin-screw extruder 30 has stabilized. Stabilizing the broken state of the glass fibers means that the resin raw material and the glass fibers are sufficiently kneaded, and a molded product in a state where quality can be secured is discharged from the discharge port 38 . In other words, at each element point inside the twin-screw extruder 30, there is no change over time in the breaking amount of the glass fiber or the degree of kneading with the resin raw material. This state is also called steady state.
- the stable kneading state of raw materials is also referred to as a steady state. A method for determining the frequency component of the AE wave W will be described later.
- FIG. 5 is a hardware block diagram showing an example of the hardware configuration of the kneading state detection device of the twin-screw extruder according to the embodiment.
- the kneading state detector 50 is used in connection with the twin-screw extruder 30 and includes the AE wave analyzer 10 and the AE sensor 20.
- the AE wave analysis device 10 includes a control section 13 , a storage section 14 and a peripheral device controller 16 .
- the control unit 13 includes a CPU (Central Processing Unit) 13a, a ROM (Read Only Memory) 13b, and a RAM (Random Access Memory) 13c.
- the CPU 13a is connected via the bus line 15 to the ROM 13b and the RAM 13c.
- the CPU 13a reads the control program P1 stored in the storage unit 14 and develops it in the RAM 13c.
- the CPU 13a controls the operation of the control section 13 by operating according to the control program P1 developed in the RAM 13c. That is, the control unit 13 has a general computer configuration that operates based on the control program P1.
- the control unit 13 is further connected to the storage unit 14 and the peripheral device controller 16 via the bus line 15 .
- the storage unit 14 is a non-volatile memory such as a flash memory, or a HDD (Hard Disk Drive) that retains stored information even when the power is turned off.
- the storage unit 14 stores programs including the control program P1 and the AE output M(t) output from the AE sensor 20 at time t.
- the control program P1 is a program for exhibiting the functions of the control unit 13 .
- the AE output M(t) is a signal obtained by converting the effective value of the detection signal D output by the AE sensor 20 into a digital signal by the A/D converter 17 .
- control program P1 may be pre-installed in the ROM 13b and provided.
- control program P1 is a file in a format that can be installed in the control unit 13 or in an executable format, and can be read by a computer such as a CD-ROM, flexible disk (FD), CD-R, DVD (Digital Versatile Disc). It may be configured to be recorded on a suitable recording medium and provided.
- the control program P1 may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the control program P1 may be configured to be provided or distributed via a network such as the Internet.
- the peripheral device controller 16 connects with the A/D converter 17, the display device 18, and the operation device 19.
- the peripheral device controller 16 controls the operation of each connected device based on commands from the control unit 13 .
- the A/D converter 17 converts the AE wave W output by the AE sensor 20 into a digital signal and outputs the AE output M(t).
- the AE sensor 20 detects the AE wave W transmitted through the housing 32 of the twin-screw extruder 30 via the waveguide rod 21 as described above.
- the AE wave W output by the AE sensor 20 is input to the A/D converter 17 after being amplified by an amplifier.
- the display device 18 is, for example, a liquid crystal display.
- the display device 18 displays various information related to the operating state of the kneading state detection device 50 .
- the display device 18 notifies that the kneading state detector 50 has reached a steady state after kneading the resin raw material and the glass fiber introduced into the twin-screw extruder 30 .
- the operation device 19 is, for example, a touch panel superimposed on the display device 18.
- the operation device 19 acquires operation information related to various operations performed by the operator on the kneading state detection device 50 of the twin-screw extruder 30 .
- the AE sensor 20 is installed on the surface of the housing 32 of the twin-screw extruder 30 in the configuration described in FIGS. Further, the AE sensor 20 differs in the frequency band of the detectable signal depending on its type. Therefore, when selecting the AE sensor 20 to be used, the raw material to be measured, the operating conditions of the twin-screw extruder 30, etc. are taken into account, and the frequency of the AE wave W expected to occur during kneading is It is desirable to choose an AE sensor 20 with high band sensitivity.
- FIG. 6 is a diagram showing an example of the results of frequency analysis of AE waves acquired by the AE wave analysis device.
- Graph 60 shown in FIG. 6 shows the amplitude X(f ) shows an example of the frequency distribution.
- the horizontal axis of graph 60 represents frequency f.
- the vertical axis of the graph 60 is the amplitude of the frequency f component obtained by performing the discrete Fourier transform on the AE output M(t). The discrete Fourier transform was performed using an FFT algorithm. Also, the AE output M(t) was sampled at a sampling frequency of 250 kHz.
- a graph 61 shows the amplitude of the AE output M(t) obtained when a constant amount of glass fiber is temporarily supplied to the resin raw material that has reached a steady state after being melted and conveyed by the twin-screw extruder 30.
- An example of the frequency distribution of X(f) is shown.
- AE output M(t) was sampled at a sampling frequency of 250 kHz as in graph 60 .
- the graph 60 has peaks at some frequencies, which are inherent frequency components generated when the twin-screw extruder 30 is in operation. These frequency components are generated by, for example, motor vibration, valve opening/closing sound, inverter noise, and the like. It was found that the AE wave W caused by the resin raw material was not generated when the twin-screw extruder 30 conveyed only the molten resin raw material.
- the inventors applied a band-pass filter from 60 kHz to 80 kHz for the amplitude X(f) shown in FIG. made it work.
- a power spectrum from 60 kHz to 80 kHz was calculated.
- the integrated value S(t) of the calculated power spectrum for 0.2 seconds was calculated, and its change over time was observed.
- Equation (1) The power spectrum P(f) of the signal of frequency f is calculated by Equation (1).
- P(f)
- 2 (X(f)*X(f))/n 2 (1)
- X(f) is the amplitude and n is the number of data points.
- FIG. 7 is a diagram showing an example of temporal changes in the integrated value of the power spectrum of 60 kHz to 80 kHz of the AE wave acquired by the AE wave analyzer.
- Graphs 62a, 62b, and 62c shown in FIG. 7 show integral values of the power spectrum of the AE output M(t) acquired by the AE wave analyzer 10 from 60 kHz to 80 kHz when the screw 44 is rotated at different rotational speeds. It shows time change.
- a graph 62a shows the integrated value S(t) when the screw rotation speed is 50 rpm.
- a graph 62b shows the integrated value S(t) when the screw rotation speed is 100 rpm.
- a graph 62c shows the integrated value S(t) when the screw rotation speed is 150 rpm.
- the integrated value S(t) monotonously increases and then monotonously decreases with the passage of time in any of the graphs. That is, it was found that the breakage of the glass fibers frequently occurred immediately after the glass fibers were added. In addition, since the length of the glass fibers becomes shorter with the passage of time, the frequency of breakage decreases, and the size (length) of the glass fibers does not change over time, that is, the kneading state of the raw materials reaches a steady state. found to reach
- FIG. 8 is a diagram explaining a method for determining whether the broken state of the glass fiber has reached a steady state based on the waveform of the AE wave acquired by the AE wave analyzer.
- the AE wave analysis device 10 first smoothes the waveform by calculating the moving average A(t) of the integral value S(t).
- a moving average is a type of low-pass filter that is used to analyze the global trend of a given waveform by smoothing it.
- the time interval for calculating the moving average can be set arbitrarily, but if the time interval is too short, noise components will remain, and if the time interval is too long, the waveform will be too dull. It is desirable to set intervals.
- the moving average A(t) is obtained from the integrated value S(t) shown in the graph 63 of FIG.
- the AE wave analysis device 10 analyzes the time change of the moving average A(t). Specifically, as shown in a graph 64 in FIG. 8, the moving average A(t) is differentiated with time to calculate the rate of change G(t) of the moving average A(t). That is, the rate of change G(t) is calculated by Equation (2).
- the moving average A(t) monotonously decreased and became moderate when the glass fiber was broken and the steady state was reached.
- the interval in which the moving average A(t) is monotonically decreasing is identified by searching for a location where a segment satisfying G(t) ⁇ 0 continues for a predetermined time ⁇ t, for example.
- section K is identified as the section in which moving average A(t) is monotonically decreasing.
- the AE wave analysis device 10 determines that the absolute values of the rate of change G(t) are all equal to or less than the threshold Th over a predetermined time ⁇ t in the section K in which the moving average A(t) is monotonically decreasing. Find the time t when For graph 64, time ta is found. That is, from the time ta to the time tb separated by the predetermined time ⁇ t, the absolute values of the rate of change G(t) are all equal to or less than the threshold Th. At time ta, the AE wave analyzer 10 determines that the breakage of the glass fibers has reached a steady state, that is, the twin-screw extruder 30 is ready to start molding the product.
- the AE wave analyzer 10 determines that the breakage of the glass fibers has not reached a steady state, that is, the operation of the twin-screw extruder 30 needs to be continued.
- FIG. 9 is a functional block diagram showing an example of the functional configuration of the kneading state detection device of the twin-screw extruder according to the embodiment.
- the control unit 13 of the kneading state detection device 50 develops the control program P1 in the RAM 13c and operates the AE wave acquisition unit 71, the kneading state determination unit 72, and the kneading state output unit 73 shown in FIG. Implemented as a functional unit.
- the AE wave acquisition unit 71 detects the housing of the twin-screw extruder 30.
- the output of the AE sensor 20 installed on the body 32 is obtained.
- the AE wave acquisition unit 71 includes an amplifier to amplify the detection signal D detected by the AE sensor 20, and the A/D converter 17 converts the effective value of the detection signal D, which is an analog signal. is converted to the AE output M(t), which is a digital signal.
- the AE wave acquisition unit 71 is an example of an acquisition unit in the present disclosure.
- the kneading state determination unit 72 determines the kneading of the resin raw material and the glass fiber based on the intensity change of the AE output M(t) of the AE sensor 20 over a predetermined time period, which is acquired by the AE wave acquisition unit 71, and the comparison with the threshold value. determine the state. Note that the kneading state determination unit 72 is an example of a determination unit in the present disclosure.
- the kneading state determination unit 72 further includes an FFT processing unit 72a, a BPF processing unit 72b, a power spectrum calculation unit 72c, an integral value calculation unit 72d, a moving average calculation unit 72e, a change rate calculation unit 72f, and a threshold value. and a processing unit 72g.
- the FFT processing unit 72a performs FFT on the AE output M(t).
- the BPF processing unit 72b performs FFT and applies a bandpass filter (BPF) in a predetermined frequency range to the result.
- the predetermined frequency range is, for example, 60-80 kHz.
- the power spectrum calculator 72c calculates the power spectrum P(f) of the predetermined frequency range calculated by the BPF processor 72b.
- the integral value calculator 72d calculates the integral value S(t) for a predetermined time for the power spectrum P(f) in the predetermined frequency range.
- the predetermined time is, for example, 0.2 seconds.
- the moving average calculator 72e calculates a moving average A(t) of the integrated value S(t).
- the change rate calculator 72f calculates the change rate G(t) of the moving average A(t).
- the threshold processing unit 72g searches for the time t when all the absolute values of the rate of change G(t) of the moving average A(t) are equal to or less than the threshold Th over the predetermined time ⁇ t. Then, the threshold processing unit 72g determines that the kneading state of the raw materials has reached a steady state at time t.
- the threshold processing unit 72g does not use the moving average A(t), and the amplitude R(t) (see FIG. 8) of the integrated value S(t) is set to the first threshold and It may be determined that the kneading state of the raw materials has reached a steady state when it is between the second threshold value that is larger than the first threshold value.
- the first threshold value and the second threshold value are appropriately set according to the conditions for kneading the raw materials.
- the kneading state output unit 73 outputs the determination result related to the raw material kneading state determined by the kneading state determination unit 72 . Note that the determination result is displayed on the display device 18 .
- the output method of the kneading state output unit 73 is not limited to this. By lighting or blinking an indicator (not shown in FIG. 5), it is notified that the broken state of the glass fibers has reached a steady state Alternatively, a sound or voice may be output from a speaker or buzzer (not shown in FIG. 5) to notify that the breakage state of the glass fibers has reached a steady state.
- FIG. 10 is a flow chart showing an example of the flow of processing performed by the kneading state detection device.
- the AE wave acquisition unit 71 acquires the AE output M(t) within a predetermined time range (step S11).
- the predetermined time is a time range within which the number of data necessary for performing the FFT in step S12 can be acquired.
- the FFT processing unit 72a performs FFT on the AE output M(t) (step S12).
- the BPF processing unit 72b applies a band-pass filter that cuts outputs outside a predetermined frequency range to the result of the FFT (step S13).
- the predetermined frequency range is 60-80 kHz.
- the power spectrum calculator 72c calculates a power spectrum for the result of applying the bandpass filter (step S14).
- the integral value calculator 72d calculates the integral value S(t) of the power spectrum (step S15).
- the moving average calculator 72e calculates the moving average A(t) of the integrated value S(t) (step S16).
- the change rate calculator 72f calculates the change rate G(t) of the moving average A(t) (step S17).
- the threshold processing unit 72g determines whether the absolute value of the change rate G(t) of the moving average A(t) is equal to or less than the threshold Th over the predetermined time ⁇ t (step S18). If it is determined that the conditions are satisfied (step S18: Yes), the process proceeds to step S19. On the other hand, if it is determined that the conditions are not satisfied (step S18: No), the process returns to step S11.
- step S18 when it is determined that the absolute value of the change rate G(t) of the moving average A(t) is equal to or less than the threshold value Th over the predetermined time ⁇ t, the threshold processing unit 72g It is determined that the state has been reached (step S19).
- the kneading state output unit 73 notifies the display device 18 that the kneading state of the raw materials has reached a steady state (step S20). After that, the kneading state detection device 50 ends the processing of FIG. 10 .
- the kneading state output unit 73 outputs the display device 18
- a notification may be given to indicate that the kneading state of the raw materials has not reached a steady state.
- the threshold processing unit 72g sets the rate of change G(t) of the moving average A(t) to a negative value over the predetermined time ⁇ t, that is, the rate of change G(t) decreases monotonically, Further, when the absolute value of the rate of change G(t) is equal to or less than the threshold value Th over the predetermined time ⁇ t, it may be determined that the kneading state of the raw materials has reached a steady state.
- the kneading state detection device 50 of the first embodiment detects when the twin-screw extruder 30 for kneading raw materials or kneading raw materials and additives is in operation.
- An AE wave acquisition unit 71 acquisition unit that acquires the AE output M(t) of the AE sensor 20 installed in the housing 32 of the extruder 30, and an AE sensor over a predetermined time acquired by the AE wave acquisition unit 71 and a kneading state determination unit 72 (determination unit) that determines the kneading state of the raw material or the raw material and the additive based on the comparison between the intensity change of the AE output M(t) of 20 and the threshold value Th.
- the twin-screw extruder 30 there is no longer any change over time in the amount of glass fiber breakage or the degree of kneading with the resin raw material. can be reliably detected.
- the kneading state of raw materials can be determined even in areas that cannot be determined by a pressure sensor, temperature sensor, torque sensor, or the like.
- waste of raw materials can be reduced.
- the kneading state detection device 50 of the first embodiment includes the integral value calculation unit 72d for calculating the integral value S(t) of the power spectrum of the AE output M(t) of the AE sensor 20 in a predetermined frequency range. and a moving average calculation unit 72e for calculating a moving average A(t) of the time change of the integrated value S(t), the kneading state determination unit 72 (determination unit) calculates the moving average A(t) When the absolute value of the rate of change G(t) is equal to or less than a predetermined threshold value Th over a predetermined period of time ⁇ t, it is determined that the raw material or the kneading state of the raw material and the additive has stabilized. Therefore, it is possible to reliably detect the kneading state of the raw materials in real time.
- the kneading state determination unit 72 determines that the moving average A(t) of the time change of the integral value S(t) monotonously decreases with time.
- the absolute value of the rate of change G(t) of the moving average A(t) is equal to or less than a predetermined threshold value Th over a predetermined period of time ⁇ t, it is determined that the kneading state of the raw materials has stabilized. Therefore, it is possible to reliably determine the kneading state of the raw material in real time.
- the kneading state determination unit 72 determines that the time change of the integrated value S(t) is the first threshold value over the predetermined time ⁇ t, If it is between the second threshold value that is larger than the first threshold value, it is determined that the kneading state of the raw materials has stabilized. Therefore, it is possible to reliably determine the kneading state of the raw material in real time.
- the AE sensor 20 is installed downstream of the twin-screw extruder 30 from the resin raw material and glass fiber inlets. Therefore, it is possible to reliably determine whether or not the kneading state of the raw materials has stabilized. Moreover, since the AE sensor 20 is attached near the kneading part, the response speed is high, and the kneading state of the raw materials can be determined in real time.
- the kneading state determination unit 72 determines unit adds glass fibers (reinforcing material) to the molten resin raw material conveyed inside the twin-screw extruder 30. It is determined that the size of the glass fiber does not change with the lapse of time. Therefore, at each element point inside the twin-screw extruder 30, it is possible to reliably determine whether the amount of glass fiber breakage has stopped changing over time, that is, whether the glass fiber breakage (kneading) state has stabilized. can do.
- the reinforcing material is glass fiber. Therefore, a molded product with improved strength can be reliably manufactured.
- the kneading state determination unit 72 determineation unit provides the twin-screw extruder 30 with unmelted resin pellets and glass fibers. (reinforcing material), the resin pellets are crushed and melted, and the size of the glass fibers does not change over time. Therefore, it is possible to reliably and easily determine the kneading state of the resin raw material and the reinforcing material.
- the twin-screw extruder 30 When the twin-screw extruder 30 is operated to knead the raw materials, the raw materials are continuously fed over a long period of time. Moreover, while the twin-screw extruder 30 is in operation, the operating conditions may be changed in the middle. The operating conditions are, for example, changes in the rotation speed of the screw 44, changes in the flow rate of the resin raw material or glass fiber to be introduced, and the like.
- the kneading state detection device 50 can determine in real time whether the kneading state of the raw materials has stabilized even during such continuous operation. In the case of continuous operation, since new raw materials and additives are constantly fed, unlike the first embodiment, AE waveforms accompanying breakage of raw materials are constantly output.
- the temporal change in the output AE waveform becomes small.
- This state is the steady state in continuous operation.
- the kneading state detection device 50 can also determine that such a steady state has been reached in continuous operation.
- FIG. 11 shows an example of the time change of the integrated value of the power spectrum when the screw rotation speed is changed while the twin-screw extruder is continuously operated and the resin raw material and the glass fiber are sufficiently kneaded.
- FIG. 4 is a diagram showing;
- the screw 44 is rotating at 50 rpm from time 0 to time td.
- time td when the kneading state reaches a steady state, the rotation speed of the screw 44 is increased to 100 rpm, and the screw 44 rotates at 100 rpm from time td to time te.
- the resin raw material is continuously fed into the supply port 36a (see FIG. 3), and from time tc, the glass fiber is continuously fed into the side feeder 37 (see FIG. 3).
- the flow rate of the resin raw material is 5 kg/h, and the flow rate of the glass fiber is 0.5 kg/h.
- the kneading state determination unit 72 of the kneading state detection device 50 detects whether the absolute value of the rate of change G(t) of the moving average A(t) of the integrated value S(t) is equal to or less than a predetermined threshold value Th over a predetermined time ⁇ t. In a certain case, it is determined that the kneading state of the raw materials has stabilized (reached a steady state).
- the graph showing the rate of change G(t) in FIG. 11 is difficult to understand because the compression ratio of the time axis is high. It was confirmed that it was below a predetermined threshold over a predetermined period of time.
- the determination method described in the first embodiment can be applied as is in sections with the same operating conditions.
- FIG. 12 shows an example of the time change of the integrated value of the power spectrum when the screw rotation speed is changed while the twin-screw extruder is continuously operated and the resin raw material and the glass fiber are sufficiently kneaded.
- FIG. 4 is a diagram showing;
- the resin raw material is continuously fed at a flow rate of 2 kg/h from time 0 to time th.
- the flow rate of the resin raw material is increased, and the resin raw material is continuously fed at a flow rate of 9 kg/h between time th and time ti.
- the glass fibers are continuously fed at a flow rate of 0.5 kg/h from time tg. Note that the rotation speed (100 rpm) of the screw 44 is constant.
- the kneading state determination unit 72 of the kneading state detection device 50a detects whether the absolute value of the rate of change G(t) of the moving average A(t) of the integrated value S(t) is equal to or less than a predetermined threshold value Th over a predetermined time ⁇ t. In a certain case, it is determined that the kneading state of the raw materials has stabilized (reached a steady state).
- the graph showing the rate of change G(t) in FIG. 12 is difficult to understand because the compression ratio of the time axis is high. It was confirmed that it was below a predetermined threshold over a predetermined period of time.
- the determination method described in the first embodiment can be applied as is in sections with the same operating conditions.
- FIG. 13 shows an example of the time change of the integrated value of the power spectrum when the twin-screw extruder is continuously operated and the resin raw material and the glass fiber are sufficiently kneaded, and the flow rate of the glass fiber is changed. It is a figure which shows.
- glass fibers are continuously fed at a flow rate of 0.5 kg/h.
- the flow rate of the glass fibers is increased, and the glass fibers are continuously introduced at a flow rate of 1 kg/h from time tl to time tm.
- the resin raw material is continuously fed from time 0 at a flow rate of 5 kg/h. Note that the rotation speed (100 rpm) of the screw 44 is constant.
- the kneading state determination unit 72 of the kneading state detection device 50a detects whether the absolute value of the rate of change G(t) of the moving average A(t) of the integrated value S(t) is equal to or less than a predetermined threshold value Th over a predetermined time ⁇ t. In a certain case, it is determined that the kneading state of the raw materials has stabilized (reached a steady state).
- the graph showing the rate of change G(t) in FIG. 13 is difficult to understand because the compression ratio of the time axis is high. It was confirmed that it was below a predetermined threshold over a predetermined period of time.
- the determination method described in the first embodiment can be applied as is in sections with the same operating conditions.
- the kneading state determination unit 72 detects the AE output M(t ), an integrated value calculator 72d that calculates an integrated value S(t) of the power spectrum in a predetermined frequency domain, a moving average calculator 72e that calculates a moving average A(t) of the integrated value S(t), , when the absolute value of the rate of change G (t) of the moving average A (t) is less than or equal to a predetermined threshold Th over a predetermined time ⁇ t, each element point inside the twin-screw extruder 30 3, it is determined that the kneading condition of the raw materials fed into the twin-screw extruder 30 no longer changes with time, that is, has reached a steady state. Therefore, even when the twin-screw extruder 30 is continuously operated and the raw materials are continuously supplied, the kneading state of the raw materials can be reliably determined.
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Abstract
Description
実施形態の説明の前に、稼働中の押出成形機の混練状態を検出するために使用するアコースティックエミッション(以下、AEと呼ぶ)について説明する。AEとは、例えば、押出成形機で樹脂原料(ペレット)を混練する際に、固体材料である樹脂ペレットが圧潰する際や、樹脂原料を強化するために混入したガラス繊維やカーボンファイバー、セルロースファイバー等の強化材が破断する際に、それまでに蓄積したひずみエネルギーを音波(弾性波、AE波)として放出する現象である。樹脂ペレットの圧潰や強化材の破断に伴って発生するAE波を検出して解析することによって、押出成形機に投入した樹脂材料の混練状態や、強化材の混練状態を予測することができる。AE波の周波数帯域は、数10kHz~数MHz程度と言われており、一般的な振動センサや加速度センサでは検出できない周波数帯域を有する。したがって、AE波を検出するためには、専用のAEセンサを用いる。AEセンサについて、詳しくは後述する。なお、本実施形態では、樹脂原料に強化材を混入するものとして説明するが、混入されるのは強化材に限定されない。例えば、タルクや炭酸カルシウム、炭酸マグネシウム等の添加剤を混入した場合であっても、以下の説明は同様に適用される。
本開示の第1の実施の形態は、樹脂原料に混入したガラス繊維の混練状態を判定する二軸押出成形機の混練状態検出装置の例である。なお、二軸押出成形機は一例であって、本実施の形態は、単軸押出成形機や多軸押出成形機等の押出成形機全般に適用可能である。
まず、図3、図4を用いて、本実施形態における二軸押出成形機30の混練状態検出装置50の概略構造について説明する。図3は、二軸押出成形機の混練状態検出装置の一例を示す概略構造図である。図4は、二軸押出成形機の出力軸の断面図である。
次に、図5を用いて、二軸押出成形機30の混練状態検出装置50のハードウェア構成について説明する。図5は、実施の形態に係る二軸押出成形機の混練状態検出装置のハイドウェア構成の一例を示すハードウェアブロック図である。
発明者らは、図3に示した二軸押出成形機30の内部を搬送される、溶融した樹脂ペレットに、供給口36bから、樹脂原料の強度を増すためのガラス繊維を、一時的に一定量供給して、当該ガラス繊維が破断される際に出力されるAE波Wを、AEセンサ20で観測した。
P(f)=|X(f)|2=(X(f)*X(f))/n2・・・(1)
ここで、X(f)は前記した振幅、nはデータ点数である。
次に、図9を用いて、実施の形態の混練状態検出装置50の機能構成を説明する。図9は、実施の形態に係る二軸押出成形機の混練状態検出装置の機能構成の一例を示す機能ブロック図である。混練状態検出装置50の制御部13は、制御プログラムP1をRAM13cに展開して動作させることによって、図9に示すAE波取得部71と、混練状態判定部72と、混練状態出力部73とを機能部として実現する。
次に、図10を用いて、実施の形態に係る混練状態検出装置50が行う処理の流れを説明する。図10は、混練状態検出装置が行う処理の流れの一例を示すフローチャートである。
前述した実施の形態では、溶融した樹脂ペレットにガラス繊維を投入した際に、混練状態検出装置50が、ガラス繊維が破断されて定常状態に達したかの判定を行う例を説明した。混練状態検出装置50は、更に、AE波Wを観測して、前記したのと同様の信号処理を行うことによって、二軸押出成形機30に投入された未溶融の樹脂ペレットが、圧潰及び溶融されて定常状態に至ったかを判定することもできる。
二軸押出成形機30を稼働させて原料を混練する際は、原料を長時間に亘って連続投入する。また、二軸押出成形機30を運転中に、途中で運転条件を変更する場合がある。運転条件とは、例えば、スクリュ44の回転速度の変更や、投入する樹脂原料又はガラス繊維の流量の変更等である。混練状態検出装置50は、このような連続運転の場面であっても、原料の混練状態が安定したかをリアルタイムで判定することができる。なお、連続運転の場合、新たな原料及び添加材が絶えず投入されるため、第1の実施の形態とは異なり、原料の破断に伴うAE波形が絶えず出力される。そして、投入された原料が二軸押出成形機30の内部に充満した状態において、出力されるAE波形の時間変化が小さくなる。この状態が、連続運転における定常状態である。混練状態検出装置50は、連続運転において、このような定常状態に至ったことも判定することができる。
図11は、二軸押出成形機を連続稼働して、樹脂原料とガラス繊維が十分に混練された状態で、スクリュの回転数を変更した場合の、パワースペクトルの積分値の時間変化の一例を示す図である。
図12は、二軸押出成形機を連続稼働して、樹脂原料とガラス繊維が十分に混練された状態で、スクリュの回転数を変更した場合の、パワースペクトルの積分値の時間変化の一例を示す図である。
図13は、二軸押出成形機を連続稼働して、樹脂原料とガラス繊維が十分に混練された状態で、ガラス繊維の投入流量を変更した場合の、パワースペクトルの積分値の時間変化の一例を示す図である。
Claims (12)
- 原料を混練、又は原料と添加剤とを混練する押出成形機が稼働状態にあるときに、当該押出成形機の筐体に設置したAEセンサの出力を取得する取得部と、
前記取得部が取得した、所定時間に亘るAEセンサの出力の強度変化と閾値との比較に基づいて、原料、又は原料と添加剤との混練状態を判定する判定部と、
を備える押出成形機の混練状態検出装置。 - 前記AEセンサの出力の、所定の周波数領域のパワースペクトルの積分値を算出する積分値算出部と、
前記積分値の時間変化の移動平均を算出する移動平均算出部と、を備えて、
前記判定部は、前記移動平均の変化率の絶対値が、所定時間に亘って所定の閾値以下である場合に、混練状態が安定したと判定する、
請求項1に記載の押出成形機の混練状態検出装置。 - 前記判定部は、前記移動平均が時間とともに単調に減少して、尚且つ当該移動平均の変化率の絶対値が、所定時間に亘って所定の閾値以下である場合に、混練状態が安定したと判定する、
請求項2に記載の押出成形機の混練状態検出装置。 - 前記判定部は、前記積分値の時間変化が所定時間に亘って、第1の閾値と、当該第1の閾値よりも大きい第2の閾値との間に収まっている場合に、混練状態が安定したと判定する、
請求項2または請求項3に記載の押出成形機の混練状態検出装置。 - 前記AEセンサは、
前記原料の投入口、又は前記原料及び前記添加剤の投入口よりも、前記押出成形機の下流側に設置される、
請求項1に記載の押出成形機の混練状態検出装置。 - 前記判定部は、前記押出成形機の内部を搬送される溶融した樹脂原料に添加剤を投入した際に、当該添加剤のサイズが時間の経過とともに変化しない状態であることを判定する、
請求項1から請求項3のいずれか1項に記載の押出成形機の混練状態検出装置。 - 前記判定部は、前記押出成形機に未溶融の樹脂原料と添加剤とを投入した際に、当該樹脂原料が圧潰及び溶融されて、尚且つ、前記添加剤のサイズが時間の経過とともに変化しない状態であることを判定する、
請求項1から請求項3のいずれか1項に記載の押出成形機の混練状態検出装置。 - 前記添加剤は、ガラス繊維である、
請求項1から請求項3のいずれか1項に記載の押出成形機の混練状態検出装置。 - 原料を混練、又は原料と添加剤とを混練する押出成形機が稼働状態にあるときに、当該押出成形機の筐体に設置したAEセンサの出力を取得して、取得したAEセンサの出力の強度変化と閾値との比較に基づいて、原料、又は原料と添加剤との混練状態を判定する、
押出成形機の混練状態検出方法。 - 前記AEセンサの出力の、所定の周波数領域のパワースペクトルの積分値を算出して、
前記積分値の時間変化の移動平均を算出して、
前記移動平均の変化率の絶対値が、所定時間に亘って所定の閾値以下である場合に、混練状態が安定したと判定する、
請求項9に記載の押出成形機の混練状態検出方法。 - 前記移動平均が時間とともに単調に減少して、尚且つ当該移動平均の変化率の絶対値が、所定時間に亘って所定の閾値以下である場合に、混練状態が安定したと判定する、
請求項10に記載の押出成形機の混練状態検出方法。 - 前記積分値の時間変化が所定時間に亘って、第1の閾値と、当該第1の閾値よりも大きい第2の閾値との間に収まっている場合に、混練状態が安定したと判定する、
請求項10に記載の押出成形機の混練状態検出方法。
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