Injection molding machine and viscosity measurement method

Abstract

The invention provides an injection molding machine and a viscosity measurement method capable of performing viscosity measurement with higher precision. The present invention relates to an injection molding machine and a viscosity measuring method, comprising: an injection cylinder in which a viscosity measuring unit can be attached and detached; and a control device which, when the inner diameter of the injection cylinder or the outer diameter of the injection shaft is D and the inner diameter of the capillary tube is d for the capillary tube mold attached to the viscosity measurement unit, calculates the injection speed Vk on the basis of formula (1) or formula (2) using three or more preset shear speed values [gamma] k (k is a natural number), and calculates the injection speed Vk on the basis of formula (1) or formula (2), where D is the inner diameter of the injection cylinder or the outer diameter of the injection shaft, and d is the inner diameter of the capillary tube mold attached to the viscosity measurement unit. Among the calculated injection velocities, the value of the injection velocity Vk within a predetermined range is automatically set as the injection velocity at the time of viscosity measurement. [Number 1] # imgabs0 #

Description

Technical Field

[0001] The present invention relates to an injection molding machine and a viscosity measuring method using the injection molding machine. Background Art

[0002] In injection molding, the viscosity of molten resin is one of the factors that affect product quality. In the viscosity measurement using a capillary rheometer, it is difficult to strictly reproduce the conditions during actual molding. Therefore, the inline screw injection molding machine of Patent Document 1 obtains the injection pressure when the molten resin is injected in a state where the mold is not in contact with the nozzle by using a pressure gauge provided at the rear end of the screw to calculate the viscosity of the molten resin.

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2004-142204 Summary of the invention

[0006] [Problems to be solved by the invention]

[0007] However, although Patent Document 1 proposes to set the injection speed setting value during viscosity measurement to be constant within a specified range, it does not provide a specific guideline for what numerical value to use. At present, the setting value of the injection speed during viscosity measurement depends on the judgment of the operator and may not be an appropriate value. In addition, the setting value of the injection speed for each viscosity measurement is not necessarily constant, so it is difficult to make a simple comparison between data due to different batches of molding materials or different measurement days.

[0008] [Technical means to solve the problem]

[0009] The injection molding machine of the present invention comprises: an injection cylinder capable of detachably attaching and detaching a viscosity measuring unit; an injection shaft located in the injection cylinder; an injection drive device for driving the injection shaft; and a control device for controlling the injection drive device to drive the injection shaft back and forth, wherein the control device uses three or more pre-set shear rate values ​​γ respectively when the inner diameter of the injection cylinder or the outer diameter of the injection shaft is set to D, and the inner diameter of the capillary of a capillary die and / or a slit die mounted on the viscosity measuring unit is set to d, and the slit length and the slit width are set to B and H, respectively. k (k is a natural number), the injection speed V is calculated based on the following formula (1) or formula (2): k , the injection speed V within the specified range among the calculated injection speeds k The value of is automatically set as the injection speed during viscosity measurement.

[0010] [Number 1]

[0011]

[0012] [Number 2]

[0013]

[0014] In addition, the viscosity measuring method of the present invention comprises: at an injection speed V k (k is a natural number), a process of causing a molding material to flow from an injection cylinder of an injection molding machine through a measuring cylinder of a viscosity measuring unit having a pressure sensor in a capillary or a slit of a mold installed in the measuring cylinder; a process of obtaining a pressure value of the molding material flowing in the measuring cylinder through the pressure sensor; and a process of calculating a pressure value related to the injection speed V using the pressure value. k The corresponding viscosity η k The step of causing the molding material to flow includes calculating, by the control device of the injection molding machine, based on the following formula (1) or formula (2), the values ​​γ of the shear speeds respectively corresponding to three or more preset values. k Corresponding injection speed V k The injection speed V in the specified range is calculated. k The value of is automatically set as the injection speed during viscosity measurement. In the following formulas (1) and (2), D represents the inner diameter of the injection cylinder or the outer diameter of the injection shaft in the injection cylinder, d represents the inner diameter of the capillary, and B and H represent the length and width of the slit, respectively.

[0015] [Number 1]

[0016]

[0017] [Number 2]

[0018]

[0019] [Effects of the Invention]

[0020] According to at least one embodiment of the present invention, it is possible to perform viscosity measurement with higher accuracy in which deviation caused by an operator is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a diagram schematically showing an example of an injection molding machine that can be applied to an embodiment of the present invention.

[0022] Figure 2 This is a schematic cross-sectional view of the injection unit 10 showing a state in which the viscosity measuring unit 5 is attached to the nozzle cylinder 45 instead of the injection nozzle 46 .

[0023] Figure 3 It is a perspective view showing an example of the appearance of the viscosity measuring unit 5 .

[0024] Figure 4 It is a perspective view showing another example of the appearance of the viscosity measuring unit 5 .

[0025] Figure 5 1 is a schematic diagram showing an exemplary vertical cross section of the viscosity measuring unit 5 .

[0026] Figure 6 It is schematically indicated Figure 5 FIG. 6 is a diagram of the VI-VI section.

[0027] Figure 7 2 is a schematic enlarged cross-sectional view of the first capillary die 62 .

[0028] Figure 8 2 is a schematic enlarged cross-sectional view of the second capillary die 63 .

[0029] Fig. 9 This is a block diagram for explaining the functions of the control device 7 of the injection molding machine 1 .

[0030] Fig.10 This is a diagram showing an example of an image displayed on the touch panel of the control device 7 in the viscosity measurement mode.

[0031] Fig.11 1 is a flowchart schematically showing an exemplary viscosity measurement method according to an embodiment of the present invention.

[0032] Fig.12 This is a diagram for explaining an example of a graph displayed on the touch panel of the operation panel when the graph drawing button 86 is pressed.

[0033] Fig.13 This is a diagram for explaining an example of displaying a graph showing the most recent measurement result and a graph showing past measurement results in an overlapping manner.

[0034] Fig.14 This is a diagram showing an example of an image displayed on the touch panel of the control device 7 in the Bagley correction mode.

[0035] Fig.15 2 is a schematic diagram showing another exemplary vertical cross section of the viscosity measuring unit 5 .

[0036] [Explanation of Symbols]

[0037] 1: Injection molding machine

[0038] 5: Viscosity measurement unit

[0039] 7: Control device

[0040] 10: Injection unit

[0041] 50: Measuring cylinder

[0042] 51: Rear cylinder

[0043] 52: Front cylinder

[0044] 61: Pressure sensor

[0045] 62: First capillary mode

[0046] 63: Second capillary mode

[0047] 64: Flow path switching pin

[0048] 67, 68: Heater

[0049] 69: Temperature sensor

[0050] 74: Display device

[0051] 82: Mode switch button

[0052] 83: Measurement start button

[0053] 86: Chart drawing button

[0054] 87: Save button

[0055] 88: Setting button

[0056] 89: Close button

[0057] 451: Nozzle mounting hole

[0058] 621: First Capillary

[0059] 631: Second capillary

[0060] 811: Measurement condition input form

[0061] 812: Measurement result display table

[0062] 813: Read the result display table

[0063] 841: Data read button

[0064] 842: Data clear button

[0065] 851: Select button

[0066] 852: Select the Release button DETAILED DESCRIPTION

[0067] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The respective characteristic matters shown in the embodiments shown below can be combined with each other. In addition, each characteristic matter can independently constitute an invention.

[0068] <1. Overall structure of injection molding machine>

[0069] Figure 1 An example of an injection molding machine to which the present invention can be applied is schematically shown. Figure 1 The injection molding machine 1 shown includes an injection unit 10 for injecting molding material, a mold clamping unit 8 for opening and closing the mold, and a control device 7 for controlling the operations of these units. Figure 1 The injection unit 10 shown in FIG. 1 is shown in schematic section.

[0070] The injection unit 10 includes a plasticizing device 2 and an injection device 4. The injection device 4 has an injection cylinder 41 and an injection shaft 42 located in the cylinder hole of the injection cylinder 41. Here, the "injection shaft" refers to an injection plunger or an injection screw arranged inside the injection cylinder. Hereinafter, the "injection plunger" is simply referred to as the "plunger". The injection screw is, for example, a straight screw described later. Figure 1 The injection shaft 42 shown is a plunger configured to be reciprocatable in the cylinder hole of the injection cylinder 41 along the axis of the injection cylinder 41 .

[0071] The injection device 4 has an injection drive device 43. The injection drive device 43 drives the injection shaft 42 forward and backward inside the injection cylinder 41 based on the instruction from the control device 7. The injection drive device 43 can adopt various drive methods such as a hydraulic cylinder or an electric motor.

[0072] exist Figure 1 In the structure shown, the injection cylinder 41, the injection shaft 42 and the injection drive device 43 are arranged in sequence in a substantially straight line. Hereinafter, the injection cylinder 41 side of the injection device 4 is sometimes referred to as the "front side" or "front", and the injection drive device 43 side is sometimes referred to as the "rear side" or "rear".

[0073] exist Figure 1 In the example shown, the front end of the injection cylinder 41 is connected to the nozzle cylinder 45. The injection cylinder 41 and the nozzle cylinder 45 have heaters 47 such as tape heaters wound around their outer peripheral surfaces, and are heated to a predetermined temperature by the heaters 47.

[0074] The nozzle cylinder 45 has a nozzle mounting hole 451 on the side opposite to the injection cylinder 41. The nozzle cylinder 45 is configured to freely detach the injection nozzle 46. For example, the inner wall of the nozzle mounting hole 451 has a female threaded portion. The injection nozzle 46 is provided with a male threaded portion having a shape corresponding to the female threaded portion of the nozzle mounting hole 451 at its rear end, thereby being detachable relative to the nozzle cylinder 45. Similar to the injection cylinder 41 and the nozzle cylinder 45, the injection nozzle 46 has a heater 48 such as a coil heater wound around the outer peripheral surface, and is heated to a predetermined temperature by the heater 48.

[0075] In the example, the side of the nozzle cylinder 45 is connected to the junction 3. The plasticizing device 2 is connected to the nozzle cylinder 45 via the junction 3. The plasticizing device 2 includes a plasticizing cylinder 21, a plasticizing screw 23 located in a cylinder hole of the plasticizing cylinder 21, a backflow prevention device 25, a plasticizing screw driving device 27 for rotating the plasticizing screw 23, and a heater 29. The plasticizing cylinder 21 has a hopper 211 at its rear end.

[0076] A supply flow path connecting the connection block 3 and the injection cylinder 41 , and a discharge flow path connecting the injection cylinder 41 and the injection nozzle 46 are provided inside the nozzle cylinder 45 . Figure 1 The injection molding machine 1 shown is a screw preplasticating type injection molding machine.

[0077] Figure 2 The injection unit 10 is shown in a state where the viscosity measuring unit 5 is attached to the nozzle cylinder 45 instead of the injection nozzle 46 .

[0078] The viscosity measuring unit 5 includes a measuring cylinder 50 having a flow path formed therein. Figure 2 In the illustrated structure, the measuring cylinder 50 has a rear cylinder 51, a front cylinder 52 and a fastening element 53. The rear cylinder 51 and the front cylinder 52 are connected by the fastening element 53. For example, the fastening element 53 is a cover nut 531. A male threaded portion having a shape corresponding to a female threaded portion formed on the inner surface of the cover nut 531 is formed at the rear end portion of the front cylinder 52. The flow path in the front cylinder 52 is connected to the flow path in the rear cylinder 51. At least one of the capillary die and the slit die described later is installed in the front cylinder 52. A pressure sensor for measuring the pressure of the fluid (typically molten resin) flowing in the flow path is installed in the front cylinder 52. A temperature sensor 69 for measuring the temperature of the fluid (typically molten resin) flowing in the flow path may also be installed in the measuring cylinder 50. For example, Fig.15As shown, a temperature sensor 69 for measuring the temperature of the fluid flowing in the flow path may also be installed in the front cylinder 52. The temperature sensor 69 is connected to the control device 7. The temperature sensor 69 may be a sensor of various types capable of measuring temperature. The temperature sensor is, for example, a thermocouple.

[0079] like Figure 2 As schematically shown, the viscosity measuring unit 5 is connected to the nozzle cylinder 45 by inserting the rear end portion of the rear cylinder 51 into the nozzle mounting hole 451 of the nozzle cylinder 45. The nozzle cylinder 45 is configured to be able to detach not only the injection nozzle 46 but also the viscosity measuring unit 5. Here, it can be said that the injection nozzle 46 and the viscosity measuring unit 5 can be indirectly detached relative to the injection cylinder 41 using the nozzle cylinder 45. The nozzle cylinder 45 can sometimes be configured as a part of the injection cylinder 41. In this case, it can be said that the injection nozzle 46 and the viscosity measuring unit 5 can be directly detached relative to the injection cylinder 41. The "injection cylinder 41 to which the viscosity measuring unit 5 can be detached" in this specification can be interpreted as including both the injection cylinder 41 to which the viscosity measuring unit 5 can be directly detached and the injection cylinder 41 to which the viscosity measuring unit 5 can be indirectly detached.

[0080] The injection molding machine 1 can measure the viscosity of the molding material (e.g., molten resin) flowing in the viscosity measuring unit 5, with the viscosity measuring unit 5 mounted on the injection cylinder 41 via the nozzle cylinder 45. The injection molding machine 1 is configured to switch the operation mode between the molding mode and the viscosity measuring mode based on the instruction of the control device 7. The molding mode is used when molding an actual product.

[0081] In the viscosity measurement mode, the control device 7 of the injection molding machine 1 calculates the injection speed based on a predetermined relationship using the value of the preset shear speed and the value of the parameter determined by the geometric characteristics of the injection cylinder 41. The control device 7 further automatically sets the calculated value as the injection speed during the viscosity measurement, operates the injection shaft 42 at the injection speed, and discharges the molding material from the viscosity measurement unit 5.

[0082] At this time, the pressure value of the molten resin as the molding material can be obtained in a state close to the actual molding by the pressure sensor of the viscosity measuring unit 5. The control device 7 calculates the viscosity of the molding material according to a predetermined relationship based on the measured value obtained from the pressure sensor, the value of the parameter that specifies the shape of the capillary or slit of the mold installed in the viscosity measuring unit 5, and the value of the shear rate used to calculate the injection speed.

[0083] According to an embodiment of the present invention, the injection speed used in the viscosity measurement mode is automatically set based on the value of the pre-set shear speed, so that high-precision viscosity measurement can be performed without relying on the operator's experience or intuition. At this time, in an embodiment of the present invention, three or more values ​​selected from an appropriate range can be prepared as the shear speed used in calculating the injection speed. The injection speed is calculated for each value of these shear speeds, and the injection speed corresponding to each shear speed is prompted to the operator as a candidate for viscosity measurement. Among the candidates for injection speed, values ​​that deviate from the specified range will not be prompted to the operator. In other words, the injection speed suitable for viscosity measurement is automatically calculated on the injection molding machine side and set as a condition for viscosity measurement.

[0084] <2. Details of the viscosity measuring unit 5>

[0085] Figure 3 and Figure 4 express Figure 2 An example of the appearance of the viscosity measuring unit 5 is shown. Figure 5 An example of a cross section when the viscosity measuring unit 5 is cut along a plane including the flow path inside the measuring cylinder 50 is schematically shown. The viscosity measuring unit 5 includes the measuring cylinder 50, and the measuring cylinder 50 has three components: a rear cylinder 51, a front cylinder 52, and a cap nut 531. The viscosity measuring unit 5 may further include a belt heater 67 wound around the outer peripheral surface of the cap nut 531.

[0086] The viscosity measuring unit 5 also includes a flow path switching pin 64 and a fixing plate 65. The flow path switching pin 64 is inserted into the flow path switching pin mounting hole 522 provided near the center of the front cylinder 52 so as to be rotatable around the axis of the front cylinder 52. The fixing plate 65 is a plate-shaped member fixed to the front surface of the front cylinder 52 by bolts or the like, and has a through hole near the center. A portion of the flow path switching pin 64 is exposed from the through hole provided near the center of the fixing plate 65. The fixing plate 65 prevents the flow path switching pin 64 from falling off from the front cylinder 52 by covering another portion of the flow path switching pin 64.

[0087] The front cylinder 52 has a first hole 525 and two second holes 526 opened on the side thereof. The first hole 525 is provided for mounting the pressure sensor 61 described later on the front cylinder 52. The second hole 526 is a through hole for inserting the positioning rod 66. The second holes 526 extend radially from the opening on the side of the front cylinder 52 to the center of the front cylinder 52. Figure 3 , a T-shaped positioning rod 66 is depicted inserted into one of the second holes 526. The front cylinder 52 has third holes 527 at two locations on the front surface. The third hole 527 is a space for arranging a heater inside. Fig.15 As shown, the front cylinder 52 may also have a fourth hole 528 opened on its side so that the temperature sensor 69 described later can be arranged.

[0088] The viscosity measuring unit 5 further includes a first capillary die 62 and a second capillary die 63 which are respectively mounted on the measuring cylinder 50. Figure 4 In the example shown, these dies 62 , 63 are arranged at intervals in the circumferential direction of the side surface of the cylindrical front cylinder 52 .

[0089] The rear cylinder 51 has a flange 513 and a plug portion 512. The flange 513 is a portion that is connected to the wall surface 531a of the rear end of the cap nut 531 when the rear cylinder 51 is connected to the front cylinder 52 by the cap nut 531. The wall surface 531a of the cap nut 531 has a function of pushing the rear cylinder 51 toward the front cylinder 52. The plug portion 512 of the rear cylinder 51 is a portion of the viscosity measuring unit 5 that protrudes further backward than the cap nut 531, and is inserted into the nozzle mounting hole 451 of the nozzle cylinder 45 when the viscosity measuring unit 5 is mounted on the nozzle cylinder 45. A male thread portion corresponding to the female thread portion of the nozzle mounting hole 451 is provided on the outer peripheral surface of the plug portion 512. The plug portion 512 is connected to the nozzle mounting hole 451 by fitting the female thread portion and the male thread portion.

[0090] The rear cylinder 51 has a flow path 511 inside that passes through the front and rear of the rear cylinder 51. The flow path 511 is connected to the flow path inside the nozzle cylinder 45 when the viscosity measuring unit 5 including the measuring cylinder 50 is mounted on the nozzle cylinder 45. The flow path 511 of the rear cylinder 51 is also connected to the flow path 521 inside the front cylinder 52 when the rear cylinder 51 is connected to the front cylinder 52.

[0091] The front cylinder 52 has a first hole 525 on its side. The first hole 525 reaches a flow path 521 extending in the axial direction of the front cylinder 52. A pressure sensor 61 is disposed in the first hole 525. The pressure sensor 61 is a pressure transducer that obtains a value of the pressure of the molding material flowing in the flow path 521. The flow path 521 of the front cylinder 52 extends to a flow path 641 of a flow path switching pin 64 provided in the flow path switching pin mounting hole 522.

[0092] Figure 6 The cross section of the measuring cylinder 50 when viewed along the axial direction of the measuring cylinder 50 is schematically shown. Figure 6 As schematically shown by the shaded circles in the figure, a heater 68 is disposed inside each of the third holes 527 opened on the front surface of the front cylinder 52. The heater 68 is, for example, a cartridge heater.

[0093] In a typical embodiment of the present invention, the viscosity measuring unit 5 is configured to be able to install more than two molds. One of the two mold mounting holes 524 provided on the side of the front cylinder 52 of the measuring cylinder 50 is installed with the first capillary mold 62, and the other is installed with the second capillary mold 63. The first capillary mold 62 and the second capillary mold 63 are molds of different specifications. More specifically, the first capillary mold 62 and the second capillary mold 63 respectively have a first capillary 621 and a second capillary 631, and at least one of the inner diameter and the effective length of the capillary is different between these molds.

[0094] The front cylinder 52 has two flow paths 523 extending radially from the center of the front cylinder 52 . One of the flow paths 523 communicates with the first capillary 621 of the first capillary die 62 , and the other communicates with the second capillary 631 of the second capillary die 63 .

[0095] exist Figure 6 In the example shown, one of the two flow paths 523 that communicates with the second capillary 631 is connected to the flow path 641 of the flow path switching pin 64 disposed inside the flow path switching pin mounting hole 522. The flow path switching pin 64 has a flow path 641 that is bent 90 degrees from the axial direction to the radial direction. Figure 6 In the state shown, the molding material delivered from the injection device 4 of the injection unit 10 to the viscosity measuring unit 5 reaches the second capillary mold 63 via the flow path 511 and the flow path 521, and the flow path 641 of the flow path switching pin 64, and is discharged from the second capillary 631 to the outside of the front cylinder 52.

[0096] The flow path switching pin 64 has a socket 642 opened on the front surface of the flow path switching pin 64. The socket 642 is, for example, a hexagonal hole and is formed in a shape that matches the front end of a hexagonal wrench. In this embodiment, the flow path switching pin 64 is located on the central axis of the front cylinder 52. Figure 6 In the state shown, the positioning rod 66 is pulled out from the second hole 526, and a hexagonal wrench is inserted into the socket 642 of the flow switching pin 64 through the through hole in the center of the fixing plate 65, so that the flow switching pin 64 is rotated counterclockwise around the axis, thereby switching the flow path of the molding material to the first capillary mold 62 side.

[0097] The flow path switching pin 64 has a recessed portion 643 on its side. The recessed portion 643 is provided at a position symmetrical to the outlet of the flow path 641 with respect to the center of the flow path switching pin 64. In addition, when the outlet of the flow path 641 is connected to any of the flow paths 523, the second hole portion 526 is also located at a position symmetrical to the outlet of the flow path 641 with respect to the center of the flow path switching pin 64. After the flow path switching pin 64 is rotated, the positioning rod 66 is inserted from the other second hole portion 526, and the front end of the positioning rod 66 is inserted into the recessed portion 643 of the flow path switching pin 64, thereby fixing the direction of the flow path switching pin 64 in the flow path switching pin mounting hole 522. In this way, the flow path switching pin 64 in the flow path switching pin mounting hole 522 can be prevented from unexpectedly rotating.

[0098] In this way, the injection molding machine 1 of the present invention is configured to be able to switch the discharge destination of the molding material between two or more molds of different specifications by being able to detach the viscosity measuring unit 5. In the example described here, the number of the flow path 523, the mold mounting hole 524 and the second hole 526 possessed by the front cylinder 52 is two. However, it is not limited to the example described above, and the number of flow paths 523, the mold mounting holes 524 and the second hole 526 corresponding to the number of molds to be used in the viscosity measurement can be set in the front cylinder 52. The viscosity measuring unit 5 can also be configured to be able to detach more than three molds. These multiple molds can be arranged in the same plane perpendicular to the central axis of the front cylinder 52. However, it is not limited to the example described above, and the multiple molds can also be arranged at positions staggered from each other along the central axis of the front cylinder 52. As described later, the viscosity measuring unit 5 can also be configured to replace the capillary mold or on the basis of the capillary mold, and can be detached from the slit mold.

[0099] In this embodiment, a female threaded portion is formed on the inner wall of each die mounting hole 524, and a male threaded portion having a shape corresponding to the female threaded portion of the die mounting hole 524 is provided on the outer peripheral surface of each of the first capillary die 62 and the second capillary die 63. In addition, a socket 622 and a socket 632 for inserting a tool are provided on the first capillary die 62 and the second capillary die 63, respectively. The socket 622 and the socket 632 are, for example, hexagonal holes, and are configured to accommodate the front end of a hexagonal wrench. The die can be easily attached to and detached from the die mounting hole 524 using a hexagonal wrench.

[0100] Figure 7 The cross section of the first capillary die 62 is schematically shown in an enlarged manner. The first capillary die 62 has a first capillary 621. The first capillary 621 has a circular cross-sectional shape having a predetermined inflow angle, inner diameter, and effective length. Figure 7 "d1" and "L1" shown in the figure respectively represent the inner diameter and effective length of the first capillary 621. The so-called inflow angle of the capillary refers to the size of the taper angle of the taper that can be formed at the inlet of the capillary. Figure 7The first capillary tube 621 having no tapered portion is exemplified. The inflow angle of the capillary tube having no tapered portion is 180°.

[0101] Figure 8 The cross section of the second capillary die 63 is schematically shown in an enlarged manner. Figure 7 The example shown also has a second capillary 631 without a taper. The second capillary 631 has an inner diameter d2 and an effective length L2 that is smaller than the effective length L1 of the first capillary 621. For simplicity, the inner diameter d2 of the second capillary 631 is equal to the effective length L1 of the first capillary 621 unless otherwise specified. Figure 7 The inner diameters d1 of the first capillary tubes 621 are shown to be the same.

[0102] <3. Example of operation of the injection molding machine 1 in the viscosity measurement mode>

[0103] Fig. 9 This is a block diagram for explaining the functions of the control device 7 of the injection molding machine 1. The control device 7 controls the injection unit 10 and the mold clamping unit 8 and calculates the viscosity of the molding material based on the pressure value of the molding material acquired by the viscosity measuring unit 5.

[0104] The control device 7 has a computing device 71, a storage device 72, an input device 73, and a display device 74. The computing device 71 includes a computing circuit such as a central processing unit (CPU), and in addition to performing various operations for controlling the various parts of the injection molding machine 1, it also performs operations related to viscosity measurement. The storage device 72 stores programs for controlling the various parts of the injection molding machine 1, data required for the computing device 71 to perform operations, etc. The storage device 72 can be implemented by any combination of a random access memory (RAM), a read-only memory (ROM), and an auxiliary storage device. These devices can be implemented by any combination of hardware and software.

[0105] The input device 73 is an input interface such as a keyboard, and the display device 74 is an output interface such as a liquid crystal display. The input device 73 and the display device 74 may be separate devices, or may be a single device that combines the functions of both, such as a touch panel. In this embodiment, as a device having the functions of the input device 73 and the display device 74, an operation panel including both a touch panel and a plurality of physical buttons is exemplified.

[0106] In the present embodiment, three or more different shear rate values ​​are stored in advance in the storage device 72. Hereinafter, k is set as a natural number, and the values ​​of these shear rates are generally expressed as γ kIn this embodiment, the shear rate value γ k The γ pre-stored in the storage device 72 is selected from a region where the molten resin as the molding material exhibits non-Newtonian fluid behavior, that is, a region where the viscosity decreases in response to an increase in shear rate. k Can be 1*10 1 sec -1 Above and 5*10 5 sec -1 3 or more different values ​​distributed as widely as possible within the following range ("*" indicates multiplication). Alternatively, γ pre-stored in the storage device 72 k Can be 1*10 1 sec -1 Above and 5*10 5 sec -1 Within the range below, three or more different values ​​are distributed as evenly as possible on the logarithmic scale. k For 1*10 1 sec -1 Above and 5*10 5 sec -1 It is more beneficial to have three or more different values ​​that are distributed as widely as possible within the following range and are as evenly spaced as possible when expressed using a logarithmic scale.

[0107] In this embodiment, the γ stored in advance in the storage device 72 k Selected from 1*10 1 sec -1 Above and 5*10 5 sec -1 The value of shear rate γ is within the range below. k For example, R can be set to a number greater than 1 and less than 5, which is R*10. 1 sec -1 、R*10 2 sec -1 、R*10 3 sec -1 、R*10 4 sec -1 and R*10 5 sec -1 Five values ​​of .

[0108] As described below, in a typical embodiment of the present invention, the apparent viscosity η is calculated by a method in accordance with Japanese Industrial Standards (JIS) K 7199:1999. ap .

[0109] Apparent viscosity η ap (unit: Pa·s) by taking the apparent shear stress τ ap (in Pa) divided by the apparent shear velocity γ ap (Unit: sec -1 In this embodiment, the shear rate γ is used. k Instead of the apparent shear velocity γ ap , calculate the following viscosity η k As the apparent viscosity η ap That is, when the shear rate γ is given within the above range k When the viscosity η is calculated by the following relational formula (3): k .

[0110] [Number 3]

[0111]

[0112] In the case of a capillary die, the apparent shear stress τ ap The capillary geometry of the die and the use of the die can be varied at a shear rate γ. k The measured value (unit: Pa) of the pressure P of the molding material when the molding material is made to flow is calculated based on the following relational expression (4).

[0113] [Number 4]

[0114]

[0115] In formula (4), d is the inner diameter of the capillary of the capillary die (in mm), and L is the effective length of the capillary (in mm). For example, if the first capillary die 62 is used, then as d and L in formula (4), the inner diameter d1 and effective length L1 of the first capillary 621 can be used respectively (refer to Figure 7 )

[0116] When the injection speed of the molding material is set to V (in mm·sec -1 ), the volume of the molding material passing through the die per unit time, i.e., the volume flow rate Q (in mm 3 ·sec -1 ) and the apparent shear velocity γ ap There is a relationship between them as shown in the following formula (5). In the following formula (5), D represents the inner diameter of the injection cylinder or the outer diameter of the injection shaft (in mm). Figure 2 In the illustrated configuration, the outer diameter of the injection shaft 42 , that is, the outer diameter of the plunger disposed in the injection cylinder 41 , may be used as D.

[0117] [Number 5]

[0118]

[0119] If the shear rate γ is used k As the apparent shear velocity γ in the above formula (5) ap , then we get the following relation (1).

[0120] [Number 1]

[0121]

[0122] In this embodiment, the above formula (1) is used for each γ k The shear velocity γ stored in advance in the storage device 72 is calculated. k Corresponding injection speed V k That is, if we take as the shear velocity γ k For example, five values ​​of V are stored in advance in the storage device 72, and five injection speeds V can be calculated. k Each V k The calculation of can be performed by the computing device 71.

[0123] In an embodiment of the present invention, the injection speed V obtained in the above manner k The pressure of the molding material is measured under the condition of 100°C. The viscosity η of the molding material is calculated according to the above formula (3) and formula (4) using the pressure value obtained by the measurement. k However, in this embodiment, for the injection speed V obtained according to the above formula (1), k V outside the specified range k , the injection speed is not used for pressure measurement.

[0124] The prescribed range of injection speed is, for example, 0.05 mm·sec -1 Above and 200mm·sec -1 If the injection speed V k The value of is within the above range, although it depends on the specifications of the mold used, it can handle a size of 1*10 6 sec -1 The shear velocity γ k .

[0125] The viscosity of the molding material using the injection molding machine 1 is measured by attaching the viscosity measuring unit 5 to the injection cylinder 41 of the injection unit 10. As described later, the viscosity may be measured by attaching a slot die to the front cylinder 52 instead of a capillary die.

[0126] Fig.10An example of an image displayed on the touch panel of the control device 7 in the viscosity measurement mode is shown. The graphical user interface (GUI) 8 includes a mode switching button 82 . Fig.10 The figure shows a state in which the screen on the operation panel is changed from "molding mode" to "viscosity measurement mode" by pressing the mode switching button 82 displayed on the touch panel of the control device 7. In addition, the installation of the viscosity measurement unit 5 can also be detected mechanically or electrically to automatically switch the mode of the injection molding machine 1 to the viscosity measurement mode.

[0127] Fig.11 1 is a flowchart showing an outline of an exemplary viscosity measuring method according to an embodiment of the present invention. The viscosity measuring method according to an embodiment of the present invention includes: a step S1 of causing a molding material to flow in a capillary or a slit of a mold mounted on a measuring cylinder 50; a step S2 of acquiring a pressure value of the molding material flowing in the measuring cylinder 50 by a pressure sensor 61 of a viscosity measuring unit 5; and a step S3 of calculating a pressure value related to an injection speed V using the acquired pressure value. k The corresponding viscosity η k Step S3.

[0128] (Step S1 of causing the molding material to flow in the capillary or slit)

[0129] The GUI 8 includes a measurement condition input table 811 in addition to the mode switching button 82. The measurement condition input table 811 has input fields for the inner diameter and effective length of the capillary attached to the die of the measuring cylinder 50. Fig.10 The "die diameter" and "die length" in the measurement condition input table 811 shown correspond to the inner diameter and effective length of the capillary, respectively.

[0130] The measurement condition input table 811 also has an input column for the injection speed used in the viscosity measurement. Here, five columns of "injection speed 1" to "injection speed 5" are displayed on the screen. These columns are columns where the operator has traditionally calculated the candidates for the injection speed manually and input them.

[0131] In this embodiment, the shear rate γ set in advance is automatically input into "injection speed 1" to "injection speed 5". k The injection speed V calculated by the control device 7 k The value of is used as a candidate for the injection speed during viscosity measurement.

[0132] The inner diameter of the injection cylinder 41 or the outer diameter of the injection shaft 42 is a known parameter determined by the specifications of the injection molding machine 1. The value of D in the above-mentioned relational expression (1) is known and is stored in advance in the storage device 72. When the computing device 71 of the control device 7 receives the input of "mold diameter" and "mold length" in the measurement condition input table 811, the value of D (here, the outer diameter of the plunger) is called from the storage device 72, and the value of D for each γ is calculated based on the relational expression (1). k V k , and automatically set it as the injection speed during viscosity measurement. The control device 7 calculates V k The value of is set as the injection speed during viscosity measurement and is displayed in five columns of "Injection speed 1" to "Injection speed 5".

[0133] However, according to V k The difference in the values ​​of the parameters used in the calculation of may result in a result that is not suitable for viscosity measurement. k , a value deviating from the specification of the injection drive device 43 may be obtained. In this embodiment, the injection speed V calculated by the control device 7 is k is within the specified range (e.g. 0.05 mm·sec -1 Above and 200mm·sec -1 Within the range below) V k The value of V is automatically set as the injection speed during viscosity measurement. The control device 7 sets V within the specified range. k The value of V is displayed on the display device 74, and the value of V deviating from the specified range is not displayed. k The value of .

[0134] Since the shear rate γ k Since five values ​​are prepared in advance, the maximum number of candidates for injection speed displayed on the GUI 8 is five. For example, some of the columns of "injection speed 1" to "injection speed 5" may be displayed as blanks for inputting no numbers. Fig.10 In the example shown, 0.2 mm / s, 2 mm / s, 20 mm / s, and 200 mm / s are displayed on the GUI 8 as "Injection speed 1" to "Injection speed 4", respectively, while the column of "Injection speed 5" is blank.

[0135] Furthermore, it is advantageous to preselect the shearing speed γ in such a way that at least three injection speed candidates are displayed on the GUI 8. k As the values ​​of d and D to be substituted into the above formula (1), for example, the following cases can be envisaged.

[0136] (a) D is within the range of 12 mm to 22 mm and d is within the range of 1 mm to 3 mm

[0137] (b) D is within the range of 23 mm to 27 mm and d is within the range of 1 mm to 4 mm

[0138] (c) D is within the range of 28 mm to 32 mm and d is within the range of 1.5 mm to 4 mm

[0139] (d) D is within the range of 33 mm to 39 mm and d is within the range of 1.5 mm to 5 mm

[0140] (e) D is within the range of 40 mm to 60 mm and d is within the range of 2 mm to 5 mm

[0141] In each case, when γ is substituted into equation (1) k For example, R*10 is used. 1 sec -1 、R*10 2 sec -1 、R*10 3 sec -1 、R*10 4 sec -1 and R*10 5 sec -1 When there are five (R is a number greater than or equal to 1 and less than or equal to 5), the five calculated V k At least three of the values ​​enter 0.05 mm·sec -1 Above and 200mm·sec -1 Within the following range.

[0142] In addition, according to the substitution of γ into equation (1) k The difference in the values ​​of d and D is sometimes used as V k In this case, the control device 7 can also be made to execute the V calculated k For example, if V k If the result is less than 1, the result is rounded to 0.01, if it is greater than 1 and less than 10, it is rounded to 0.1, and if it is greater than 10, it can be rounded to 1. On this basis, the calculation result can be rounded to within the specified range (for example, 0.1 mm·sec in this case). -1 Above and 200mm·sec -1 The following range) is used as the value of V k , and automatically set as a candidate for injection speed during viscosity measurement. Fig.10 To set the value of R equal to 5, as γ k And using 5*10 1sec -1 , 5*10 2 sec -1 , 5*10 3 sec -1 , 5*10 4 sec -1 and 5*10 5 sec -1 The five values ​​of , and set as d = 2mm, D = 16mm. Fig.10 In the "Injection Speed ​​1" to "Injection Speed ​​4" columns, enter the set values ​​in order from the smallest value after performing appropriate rounding. k The value is 5*10 5 sec -1 When V k It is outside the range, so the column of "Injection speed 5" is blank.

[0143] Thus, the viscosity measuring method according to the embodiment of the present invention includes the following steps: the control device 7 automatically calculates V based on a predetermined relational expression such as the relational expression (1). k , will be within the specified range of V k The value of is automatically set as the injection speed during viscosity measurement. The above process can also be executed by, for example, providing an "automatic input button" in the measurement condition input table 811 and having the operator press the automatic input button.

[0144] The operator selects one of the injection speed candidates displayed on the GUI 8. For example, when the operator touches one of the injection speeds displayed in the columns of "injection speed 1" to "injection speed 5", the calculation device 71 acquires the V when controlling the injection drive device 43. k The value of .

[0145] When the operator selects an injection speed and presses the measurement start button 83 of the GUI 8, the control device 7 sends a control signal to the injection drive device 43 to perform the injection at the selected injection speed V. k The injection axis 42 is driven. Based on the input data and the set value, the viscosity measuring unit 5 injects the molding material to measure the viscosity of the molding material.

[0146] The injection device 4 may also have an encoder 44 (see Fig. 9 The encoder 44 is a sensor for reading the axial position of the plunger as the injection axis 42 in the injection cylinder 41. The moving speed of the injection axis 42 (equivalent to the injection speed) is calculated by the position information of the injection axis 42 read by the encoder 44 and the timing by a timer, for example. In the viscosity calculation using the above formula (3), the injection speed V can be used as a set value. kAlternatively, an actual measured value of the injection speed calculated based on the output of the encoder 44 may be used.

[0147] (Step S2 of Obtaining the Pressure Value of the Molding Material Flowing in the Measuring Cylinder)

[0148] The molding material introduced into the flow path inside the measuring cylinder 50 flows into the capillary die mounted on the front cylinder 52 via the measuring cylinder 50 including the front cylinder 52 mounted with the pressure sensor 61. The molding material introduced into the measuring cylinder 50 sequentially passes through the flow path 511, the flow path 521, and the flow path 641 (see Figure 5 ), thereby reaching the second capillary die 63.

[0149] During the process of the molding material passing through the flow path 521 of the front cylinder 52, the control device 7 obtains the pressure measurement value of the molding material flowing in the flow path 521 through the pressure sensor 61. The pressure value measured by the pressure sensor 61 may change during the injection of the molding material. The pressure value used in the viscosity calculation can be the value at the time point when the measured pressure value becomes approximately constant. It can also be the average of the time of a specified period after a certain period of time has passed since the injection shaft 42 started to drive. The reason is that in the second half of the injection, it is expected that the pressure of the molding material converges within a substantially constant range.

[0150] The installation position of the pressure sensor 61 only needs to be in the flow path on the upstream side of the first capillary die 62 and the second capillary die 63. It is advantageous for the pressure sensor 61 to be located as close as possible to the first capillary die 62 and the second capillary die 63. The pressure sensor 61 of this embodiment is fixed to the first hole 525 to measure the pressure of the molding material flowing in the flow path 521 of the front cylinder 52.

[0151] (Calculate and injection speed V k The corresponding viscosity η k Process S3)

[0152] The calculation device 71 of the control device 7 receives the measured value obtained by the pressure sensor 61 and calculates the injection speed V which is currently selected based on the above-mentioned relational expressions (3) and (4). k The corresponding viscosity η k The control device 7 calculates the viscosity η k The value of is displayed on the display device 74. Fig.10 In the example shown, the viscosity η k The value of the injection speed V used in the pressure measurement k The value and shear velocity γ kThe values ​​of are displayed together in the row of “this time” in the measurement result display table 812. The measurement result display table 812 is a portion of the GUI 8 that displays data obtained from the current viscosity measurement and parameters used in the current measurement.

[0153] The injection speed setting can be changed to perform multiple pressure measurements and viscosity calculations. In a typical embodiment of the present invention, when V is within a specified range, k The pressure is measured and the viscosity is calculated at each value of. Fig.10 In the example shown, the control device 7 operates the injection drive device 43 for each injection speed shown in the columns of "Injection speed 1" to "Injection speed 4", and performs pressure measurement and viscosity calculation at each injection speed. k At least four measurement results corresponding to the value of. The control device 7 sets the injection speed V k , shear rate γ k and viscosity η k The values ​​of are displayed at a glance in the measurement result display table 812.

[0154] In this embodiment, three or more pre-set shear rate values ​​γ are set. k The data is stored in the storage device 72. For example, if the inner diameter d of the capillary of the mold is input, a plurality of injection speeds corresponding to the specifications of the injection axis 42 can be automatically input. The deviation of the measurement conditions between each operator can be eliminated. It is also easy to compare the viscosity measurement results obtained in the past by other operators.

[0155] In addition, for example, the inner diameter d of the capillary of the mold and the injection speed V k The values ​​of d are associated with each other and stored in the storage device 72 in the form of a table. By referring to this table, the injection speed V corresponding to the value of d can also be automatically input. k As shown in this embodiment, the injection speed V is calculated by receiving the input of the inner diameter d of the capillary and causing the calculation device 71 to calculate the injection speed V. k This provides the advantage of automatically prompting an appropriate injection speed even when a capillary mold of a previously unavailable specification is newly used.

[0156] Get the viscosity η k After the measurement results are obtained, the control device 7 can draw a graph showing the viscosity η k The value of shear velocity γ k A diagram of the relationship between Fig.10In the example shown, the GUI 8 includes a selection button 851, a selection release button 852, and a graph drawing button 86. For example, the operator clicks one or more rows of data displayed in the measurement result display table 812 to temporarily select these rows, and then presses the selection button 851 to select the temporarily selected row. The selection release button 852 is a button for releasing the selection at this time. If the graph drawing button 86 is pressed in a state where one or more rows in the measurement result display table 812 are selected, the control device 7 draws the value γ representing the shear speed based on the data of the selected row. k and viscosity η k The control device 7 detects the pressing of the graph drawing button 86 and displays the graph of the relationship between the values ​​of and on the display device 74. For example, the control device 7 detects the pressing of the graph drawing button 86 and presents the operator with a double logarithmic or single logarithmic rheological curve (sometimes also referred to as a flow curve).

[0157] Fig.12 An example of a graph displayed on the touch panel of the operation panel when the graph drawing button 86 is pressed is shown. Fig.12 The three injection speeds V are shown in the form of a graph. k Viscosity η k Examples of measurement results. Fig.12 The horizontal axis of the graph shown represents the shear rate γ k , the vertical axis represents viscosity η k .like Fig.12 As shown in the diagram, the viscosity η can be measured at each k When the temperature sensor 69 is used, the actual value T of the temperature of the molding material measured by the temperature sensor 69 is displayed. k In the chart, the measured value of the temperature of each part measured by at least one of the temperature sensors 291, 471, 671, and 681 described later may also be displayed together. The displayed measured value of the temperature is, for example, a representative value sampled in one viscosity measurement. In the chart, at least one of the set values ​​for controlling the temperature of the heater 29, the heater 47, the heater 67, and the heater 68 may also be displayed together.

[0158] By k The results of the determination of shear rate γ k (or injection speed V k ) is established in a corresponding form as a chart and presented to the operator, so that the operator can visually and intuitively grasp the viscosity characteristics of the molding material at the molding site. The data of the chart can be stored as image data in an auxiliary storage device of the storage device 72 or an external storage medium 75 such as a flash memory (see Fig. 9 ).

[0159] like Fig.12The graph shown is preferably a graph of V used in viscosity measurement for a certain mold. k The value of is more than three, in other words, the number of points plotted is more than three. The reason is that when the shear velocity value γ k The horizontal axis is the viscosity η k When the vertical axis is at least a straight line fit can be performed. The number of points drawn can also be four or more. In this case, a curve regression can be performed.

[0160] It is desirable that the setting values ​​of the injection speed used in the viscosity measurement be appropriately dispersed. Even for a skilled operator, finding three or more effective and mutually different injection speeds is a complicated task that requires effort and time.

[0161] According to an embodiment of the present invention, based on three or more pre-set shear rate values ​​γ k And can automatically set the k A graph showing the viscosity characteristics of the molding material can be obtained independently of the operator's skill level.

[0162] The control device 7 may also be configured to draw a graph based on data obtained from past viscosity measurements. The GUI 8 includes, in addition to the measurement result display table 812, a read result display table 813 that displays data obtained from past viscosity measurements for each injection speed at a glance. The GUI 8 also includes a data read button 841. When the control device 7 detects that the data read button 841 is pressed, the data stored in the auxiliary storage device of the storage device 72 or the external storage medium 75 is referenced and displayed in the read result display table 813.

[0163] The operator can select data in the read result display table 813 in the same manner as selecting data in the measurement result display table 812. When selecting data from the measurement result display table 812 and the read result display table 813, the step of temporarily selecting can be set as the selection step, and the step of selecting the button 851 can be omitted. In this case, the selection button 851 can be omitted from the GUI 8.

[0164] When it is detected that the operator has pressed the graph drawing button 86 while multiple rows of the reading result display table 813 are selected, the control device 7 displays the past viscosity measurement results in the form of a graph based on the data of the selected row on the display device 74. In addition to selecting the data included in the reading result display table 813, the data included in the measurement result display table 812 can also be selected, and multiple graphs related to the measurement results can be displayed in a superimposed manner on one screen.

[0165] Fig.13An example of displaying a graph showing the most recent measurement result and a graph showing the past measurement result in a superimposed form is shown. Even if the injection speed is set to be the same, data obtained in measurements at different heater temperatures are displayed on the screen as graphs C1 to C3. According to this embodiment, data under different measurement conditions, such as viscosity between data measured on different dates, can be easily compared, and differences in the behavior of the molding material caused by different batches of the molding material can also be visually grasped.

[0166] (Switching of the discharge destination of molding material)

[0167] In this embodiment, the flow path switching pin 64 disposed in the flow path switching pin mounting hole 522 is rotated around the axis of the measuring cylinder 50 to change the direction of the outlet of the flow path 641, so that the discharge destination of the molding material can be switched between multiple molds. For example, in the case of Bagley correction, when calculating the viscosity, it is necessary to switch the mold in addition to two pressure measurements. According to the embodiment of the present invention, Bagley correction can be easily implemented on the injection molding machine 1 without preparing multiple devices for viscosity measurement.

[0168] Bagley correction is a correction for obtaining the true shear stress τ by taking into account the pressure loss generated at the inlet and outlet of the capillary of the mold. In order to more accurately measure the viscosity of the molding material, it is advantageous to perform Bagley correction. The control device 7 may also be configured so that by pressing the mode switching button 82 of the GUI 8, the screen changes from Fig.10 The "simple measurement mode" shown is transformed into Fig.14 The "Bagley correction mode" shown. The "measurement mode" of the injection molding machine 1 may have two or more modes. The "measurement mode" of the injection molding machine 1 may further have a mode for performing Rabinowitsch correction described later.

[0169] Fig.14 The measurement condition input table 811 of the illustrated "Bagley correction mode" has two input fields for "die length." For example, when the first capillary die 62 and the second capillary die 63 are mounted on the measurement cylinder 50, the effective length L1 of the first capillary 621 and the effective length L2 of the second capillary 631 are input in the two input fields for "die length."

[0170] When the molding material passes through the capillary, pressure loss generally occurs at the inlet, inside and outlet of the capillary. By subtracting the estimated pressure P0 when the effective length of the capillary is assumed to be 0 mm from the pressure value P of the molding material when the capillary die is used, the pressure value (P-P0) when it is assumed that no pressure loss occurs at the capillary inlet and capillary outlet can be estimated. Taking into account the true shear stress τ of the Bagley correction, it is expressed using the following formula (6).

[0171] [Number 6]

[0172]

[0173] If the pressure value of the molding material when using the first capillary die 62 is P1 and the pressure value of the molding material when using the second capillary die 63 is P2, the estimated pressure P0 related to the first capillary die 62 can be obtained by the following formula (7).

[0174] [Number 7]

[0175]

[0176] When performing Bagley correction, it is necessary to switch the mold and perform at least two pressure measurements.

[0177] According to the embodiment of the present invention, the discharge destination of the molding material can be easily switched between the first capillary die 62 and the second capillary die 63. After the positioning rod 66 is pulled out from the second hole 526 and the flow path switching pin 64 is rotated to an appropriate angle, the positioning rod 66 is inserted from the other second hole 526 and the front end of the positioning rod 66 is inserted into the recess 643 of the flow path switching pin 64. In this way, the discharge destination of the molding material can be switched from the second capillary die 63 to the first capillary die 62.

[0178] The discharge destination of the molding material is set to the second capillary die 63 and the pressure value P2 of the molding material is obtained. After the pressure value P2 is obtained, for example, the control device 7 displays a message on the touch panel of the operation panel to remind the operator to switch the mold. The operator switches the direction of the flow path switching pin 64 and switches the discharge destination of the molding material to another mold (here, the first capillary die 62). The control device 7 receives the completion of the mold switching, for example, through an input from the operator, and switches the injection speed V to the same as before. k Next, pressure measurement of the molding material is performed using the first capillary die 62.

[0179] By switching the discharge destination of the molding material to the first capillary die 62 and allowing the molding material to flow in the first capillary 621 of the first capillary die 62, the pressure value P1 of the molding material can be acquired by the pressure sensor 61. In this way, the process of acquiring the pressure value of the molding material may also include the process of switching two or more dies as the introduction destinations of the molding material through the measuring cylinder 50 and acquiring the pressure values ​​separately. In addition, when the inner diameter d2 of the second capillary 631 is different from the inner diameter d1 of the first capillary 621, the injection speed V appropriate for each capillary can be automatically set. k .

[0180] The switching of the mold is not limited to the switching between two capillary molds of different specifications. For example, the viscosity measuring unit 5 can also be configured to be able to switch the discharge destination of the molding material between a capillary mold and a slit mold having a slit with a rectangular cross-section. Alternatively, the viscosity measuring unit 5 can also be configured to be able to switch the discharge destination of the molding material between a plurality of slit molds.

[0181] In this embodiment, a female thread is formed on the inner wall of the die mounting hole 524 of the front cylinder 52. It is also easy to mount the slot die having a male thread corresponding to the female thread of the die mounting hole 524 on the outer peripheral surface.

[0182] When the viscosity is measured using a slit die instead of a capillary die, if the effective length of the slit is L (in mm), the apparent shear stress τ can be calculated using the following equation (8) instead of the above equation (4): ap (Here, for simplicity, the inflow angle of the slit is set to 180°.) In the following formula (8), P s is the pressure value of the molding material when using the slit die (in Pa). In addition, in the following formula (8), H represents the slit length (in mm), and B represents the slit width (in mm). In addition, the "slit length" and "slit width" in this specification correspond to the "slit gap" and "slit width" in JIS K 7199:1999, respectively.

[0183] [Number 8]

[0184]

[0185] As the apparent shear velocity γ ap The formula can be replaced by the following formula (9).

[0186] [Number 9]

[0187]

[0188] As the apparent shear rate γ in the formula (9) ap , if a preset shear rate γ k is used, the following relational expression (2) is obtained.

[0189] [Equation 2]

[0190]

[0191] Similarly to the case of applying a capillary die, the control device 7 will use the shear rate γ k and the injection rate V calculated based on the formula (2) k within a specified range in k is automatically set as the injection rate during viscosity measurement. In addition, the control device 7 operates the injection driving device 43 at an injection rate selected from these V k , receives the measured value from the pressure sensor 61, and thereby can calculate the viscosity η k corresponding to V k .

[0192] In the case of performing Bagley correction using two slit dies with different specifications, as long as the following formula (10) is applied instead of the formula (6) to obtain the true shear stress τ. To obtain the estimated pressure P0 in the formula (10), P1 and P2 in the formula (7) are respectively replaced with the pressure values of the molding material when using the first slit die and the pressure values of the molding material when using the second slit die, and L1 and L2 (assuming L2 < L1) are respectively replaced with the effective length of the slit of the first slit die and the effective length of the slit of the second slit die.

[0193] [Equation 10]

[0194]

[0195] In the case of using multiple dies by switching, at the same injection rate, due to the different geometric shapes of the capillary or slit, the magnitude of the actual shear rate may also change. In the case of presenting the viscosity measurement results in a graph to the operator, if the value of the shear rate γ k used in the calculation of the injection rate V k is made consistent among multiple dies, the comparison of the measurement results becomes easy, and thus it is convenient.

[0196] The control device 7 can also be configured to, for example, by being selected by the operator, perform Rabinowitsch correction instead of or on the basis of Bagley correction. By performing at least one of Bagley correction and Rabinowitsch correction, preferably both, more accurate viscosity measurement can be performed.

[0197] The apparent shear velocity γ ap This is the shear rate when the structural viscosity index n of the molding material to be measured is 1, that is, when the molding material is a Newtonian fluid. However, actual molding materials are generally non-Newtonian fluids, so the true shear rate γ and the apparent shear rate γ ap The Rabinovich correction is performed by multiplying the apparent shear rate γ by a specified coefficient determined by the structural viscosity index n. ap And get the correction of the real shear velocity γ.

[0198] When a capillary die is used, the true shear rate γ obtained by Rabinovich correction is expressed by the following equation (11). When a slit die is used, the true shear rate γ obtained by Rabinovich correction is expressed by the following equation (12).

[0199] [Number 11]

[0200]

[0201] [Number 12]

[0202]

[0203] Here, the structural viscosity index n is calculated by the following formula (13).

[0204] [Number 13]

[0205]

[0206] The true shear stress τ and the true shear rate γ can be obtained by Bagley correction and Rabinovich correction, respectively. At this time, the true viscosity η is obtained as the value obtained by dividing τ by γ (τ / γ). Rabinovich correction can be performed frequently, and the operator can switch whether to perform Rabinovich correction at will. In the case of performing Rabinovich correction without Bagley correction, the apparent shear stress τ is used in the calculation instead of the true shear stress τ. ap When at least one of Bagley correction and Rabinovich correction is performed, the corrected viscosity η k The value of is displayed on the vertical axis of the viscosity characteristic graph, the measurement result display table 812, and the read result display table 813. When the Rabinovich correction is implemented, the corrected shear rate γ is k It is displayed on the horizontal axis of the viscosity characteristic graph, the measurement result display table 812 and the reading result display table 813 .

[0207] In the above example, the flow path switching pin 64 can be rotated manually using a tool. Without being limited to the above example, the flow path switching pin 64 can also be automatically rotated by various driving devices such as a hydraulic cylinder, a pneumatic cylinder, or an electric motor. The switching of the mold caused by the rotation of the flow path switching pin 64 can also be controlled by the control device 7.

[0208] When performing Bagley correction, multiple modes having different specifications other than effective length may be used.

[0209] Even when Bagley calibration is not performed, viscosity measurement can be performed by switching between multiple dies of different specifications.

[0210] If the mold mounting hole 524 of the viscosity measuring unit 5 is arranged to face approximately downward, it is easy to recover the molding material discharged from the mold. Figure 6 It is understood that, in front view, the angle between the straight line parallel to the central axis of the mold mounting hole 524 and the vertical line passing through the center of the front cylinder 52 is preferably less than about 40°. The vertical line passing through the center of the front cylinder 52 is a straight line parallel to the direction of gravity.

[0211] The fastening element 53 may be a bolt or the like instead of the cap nut 531 .

[0212] <4. Others>

[0213] Hereinafter, other parts of the structural example of the injection molding machine 1 will be briefly described.

[0214] During injection molding and viscosity measurement, the control device 7 controls the operation of the plasticizing screw drive device 27, the backflow prevention device 25 and the injection drive device 43 of the injection unit 10 to perform melting, metering and injection of the molding material.

[0215] The control device 7 controls the heater 29, the heater 47, the heater 48, the heater 67 and the heater 68 to heat the plasticizing cylinder 21, the injection cylinder 41, the nozzle cylinder 45, the injection nozzle 46 and the viscosity measuring unit 5 to the desired temperature. In the molding mode, the heater 67 and the heater 68 of the viscosity measuring unit 5 are not used. In the viscosity measuring mode, the heater 48 of the injection nozzle is not used. The injection unit 10 may also include: a temperature sensor 291 for measuring the temperature of the plasticizing cylinder 21, a temperature sensor 471 for measuring the temperature of the injection cylinder 41 and the nozzle cylinder 45, a temperature sensor 481 for measuring the temperature of the injection nozzle 46, a temperature sensor 671 for measuring the temperature of the rear cylinder 51 of the viscosity measuring unit 5, and a temperature sensor 681 for measuring the temperature of the front cylinder 52 of the viscosity measuring unit 5. The temperature sensors 291, 471, 481, 671 and 681 may be various types of sensors capable of measuring temperature. For example, the temperature sensor 291, the temperature sensor 471, the temperature sensor 481, the temperature sensor 671, and the temperature sensor 681 are thermocouples or the like. Each of the temperature sensors 291, 471, 481, 671, and 681 is connected to the control device 7. The control device 7 can perform feedback control on the heater 29, the heater 47, the heater 48, the heater 67, and the heater 68 corresponding to each of the temperature sensors 291, 471, 481, 671, and 681 based on the measurement values ​​obtained from each of the temperature sensors 291, 471, 481, 671, and 681. The control device 7 can also perform feedback control on the heater 67 and the heater 68 based on the measurement values ​​obtained from the temperature sensor 69 instead of the temperature sensor 671 and the temperature sensor 681.

[0216] The mold clamping unit 8 is configured to open, close, and clamp the mounted mold. The mold clamping unit 8 closes the mold and applies a predetermined clamping force to the mold before injecting the molding material into the mold. After the molding material solidifies in the mold, the mold is opened and the molded product is ejected. The mold clamping unit 8 can adopt a known structure such as a direct pressure type or a toggle type.

[0217] The injection unit 10 injects the molding material from the injection nozzle 46 or the viscosity measuring unit 5 after plasticizing the polymer particles and measuring a predetermined amount. The polymer particles are put into the plasticizing cylinder 21 from the hopper 211. "Molding material" is not limited to polymer particles, and includes various materials that can be injected by an injection molding machine. "Molding material" includes, in addition to resin materials, Metal Injection Molding (MIM) materials in which a resin as a binder is added to metal powder, and Ceramic Injection Molding (CIM) materials in which a resin as a binder is added to ceramic powder. The molding material may be thermoplastic or thermosetting. Thermosetting molding materials are, for example, liquid injection molding (LIM) materials that are thermosetting liquid materials.

[0218] The plasticizing cylinder 21 is heated to a predetermined temperature by a heater 29 such as a belt heater. The molding material supplied to the plasticizing cylinder 21 is melted by the heat from the heater 29 and the shear heat caused by the rotation of the plasticizing screw 23, and is sent to the front of the plasticizing cylinder 21 as the plasticizing screw 23 rotates.

[0219] The plasticizing screw driving device 27 rotates the plasticizing screw 23. The plasticizing screw driving device 27 can be driven by various driving methods such as a hydraulic motor or an electric motor. The backflow prevention device 25 prevents the molding material from flowing back into the plasticizing cylinder 21 during injection by advancing the plasticizing screw 23 and blocking the flow path with the front end of the plasticizing screw 23. The backflow prevention device 25 can be driven by various driving methods such as a hydraulic cylinder, a pneumatic cylinder, an electric cylinder or an electric motor. The backflow prevention mechanism can also use a check valve or a rotary valve set in the middle of the flow path instead of the backflow prevention device 25.

[0220] The molding material sent out from the plasticizing device 2 is introduced into the injection cylinder 41 of the injection device 4 via the connecting block 3 connecting the plasticizing device 2 and the injection device 4, and the nozzle cylinder 45. A supply flow path for sending the molding material from the plasticizing cylinder 21 to the nozzle cylinder 45 is formed inside the connecting block 3. The connecting block 3 can also be heated to a predetermined temperature by a heater.

[0221] The molding material sent into the injection cylinder 41 is temporarily stored in front of the injection axis 42 while the injection axis 42 is retracted, thereby being measured into a desired amount.

[0222] After the molding material is metered, the plasticizing screw 23 is advanced through the backflow prevention device 25, and the front end of the plasticizing screw 23 blocks the flow path connecting the plasticizing cylinder 21 and the connecting block 3. After preventing the backflow of the molding material, the injection shaft 42 advances and delivers the molding material to the injection nozzle 46 via the nozzle cylinder 45. In this way, the molding material is injected from the injection nozzle 46.

[0223] In the viscosity measurement mode, the viscosity measurement unit 5 is installed on the injection unit 10 instead of the injection nozzle 46, and the molding material is melted, measured, and injected in the same manner as when the molding mode is selected. In this embodiment, the measured value during the viscosity measurement is set to the maximum value that can be measured by the injection unit 10. The set value of the measurement is not limited to the maximum value that can be measured, and can be appropriately determined within the range that can be measured stably.

[0224] The molding material extruded by the injection shaft 42 passes through the nozzle cylinder 45 and sequentially passes through the flow path 511, the flow path 521, the flow path 641 and the flow path 523 inside the viscosity measuring unit 5, and is discharged from one of the plurality of molds. At this time, the pressure of the molding material flowing in the flow path 521 is measured by the pressure sensor 61.

[0225] Next, Fig.10 and Fig.14 The temperature data displayed and stored below are, for example, set values ​​for controlling the temperatures of heaters 29, 47, 67, and 68; actual values ​​of the temperatures of the respective parts measured by temperature sensors 291, 471, 481, 671, and 681 provided in the respective parts; and actual values ​​of the temperature of the molding material measured by temperature sensor 69. k The measured value of the temperature displayed or stored is, for example, a representative value sampled in a single viscosity measurement.

[0226] The GUI 8 in the viscosity measurement mode includes a measurement condition input table 811, a measurement result display table 812, and a read result display table 813. The GUI 8 may also have a function for displaying the actual measured values ​​of the temperature of each part and the actual measured value T of the molding material in real time. k Display some or all of the columns.

[0227] The measurement condition input table 811 has an input column for data required for calculating viscosity and setting values ​​related to viscosity measurement. In the example, the operator inputs the specifications of the mold (for example, the inner diameter and effective length of the capillary in the case of a capillary mold), a measurement name that can be arbitrarily set, etc. through the touch panel as the input device 73. In this embodiment, the injection speed column automatically inputs a plurality of pre-set shear speeds γ. kCorresponding multiple V k In one embodiment, the control device 7 changes the injection speed in the order of V1, V2, V3, ... to perform multiple viscosity measurements. k The corresponding V k In addition to the mode, the operator can also prepare an additional mode in which an arbitrary value can be manually input as the injection speed.

[0228] The reading result display table 813 is a part that displays the data obtained by the past viscosity measurement for each injection speed. The operator can compare the data shown in the measurement result display table 812 with the data shown in the reading result display table 813. Comparison of these data makes it easy to understand the characteristics of the molding material.

[0229] The data displayed in the measurement result display table 812 and the read result display table 813 include, for example, the data of the injection speed, shear speed, pressure measurement value of the molding material, viscosity, temperature, and measurement name. For example, the data of the injection speed and temperature may display either the set value or the actual value, or both the set value and the actual value. When the estimated actual value is substantially the same as the set value, the display of the actual value may be omitted.

[0230] The data displayed in the measurement result display table 812 and the read result display table 813 may be part of the data related to the measurement result. The items of data displayed in the measurement result display table 812 and the read result display table 813 can be arbitrarily selected by the operator.

[0231] The GUI 8 includes a data clear button 842, a save button 87, a setting button 88, and a close button 89. The data clear button 842 is a button for instructing the calculation device 71 to reset the data displayed in the measurement result display table 812 and the read result display table 813.

[0232] When the save button 87 is pressed, the data related to the measurement results are saved in an auxiliary storage device of the storage device 72 or an external storage medium 75 such as a flash memory in an arbitrary form such as a comma-separated value (CSV) form. The output and saved data may include data such as the specifications of the mold measured each time, the injection speed, the shear speed, the pressure measurement value, the viscosity, the temperature and the measurement name. For example, the injection speed and temperature data may be saved as either a set value or a measured value, or both the set value and the measured value. In the case where the predicted measured value is substantially the same as the set value, the saving of the measured value may also be omitted. In the case where corrections such as Bagley correction and Rabinovich correction are implemented, the data of the corrected viscosity, or the data of both the viscosity before correction and the viscosity after correction may also be saved. In the case where corrections such as Rabinovich correction are implemented, the data of the corrected shear speed, or the data of both the shear speed before correction and the shear speed after correction may also be saved.

[0233] The setting button 88 is a button for calling a predetermined setting screen. In this embodiment, the conditions that do not need to be changed in each viscosity measurement are displayed in the same manner as the measurement condition input table 811. Fig.10 For example, the diameter of the plunger of the injection axis 42, the shear velocity γ k , injection speed V k The range, temperature rise waiting time, etc. are input from the screen displayed by pressing the setting button 88. If the parameters such as the plunger diameter determined by the specifications of the injection molding machine 1 are automatically input by referring to the data related to the model of the injection molding machine 1, the input column for the parameters can be omitted.

[0234] The close button 89 is a button for switching the screen from the GUI 8 for viscosity measurement to the GUI for molding mode.

[0235] In this embodiment, the heater temperature of each part of the injection molding machine 1 is set from the GUI for the molding mode. An input column related to the heater temperature can also be set in the measurement condition input table 811. The set temperature of the heater 29, the heater 47, the heater 67, and the heater 68 is usually input at the same temperature. When performing viscosity measurement, it is desired that the temperature of each part where the molding material flows is stable. After moving from the GUI for the molding mode to the GUI 8 for viscosity measurement, a restriction can be set so that the viscosity measurement cannot be started before the set temperature rise waiting time has passed, thereby ensuring temperature stability.

[0236] As shown in the examples, the present invention is not limited to the structure of the embodiment shown in the drawings, and can be applied to other injection molding machines such as an inline screw injection molding machine. The inline screw injection molding machine has an injection cylinder and an inline screw as an injection shaft 42 arranged inside the injection cylinder. The inline screw has both the function of the plasticizing screw 23 of the injection molding machine 1 and the function of the plunger as the injection shaft 42. However, compared with the inline screw injection molding machine, the screw pre-plasticizing injection molding machine has excellent stability in the metering and injection of the molding material, and it can be expected that the viscosity of the molding material can be measured more accurately.

[0237] The embodiments are selected to illustrate the principles of the invention and its practical application. Various modifications can be made with reference to the above description. The scope of the invention is defined by the appended claims.

Claims

1. An injection molding machine, comprising: Injection cylinder, capable of disassembling and assembling the viscosity measuring unit; An injection shaft, located in the injection cylinder; An injection drive device drives the injection axis; as well as a control device for controlling the injection drive device to drive the injection axis back and forth, The control device uses three or more pre-set shear rate values ​​γ respectively when the inner diameter of the injection cylinder or the outer diameter of the injection shaft is set to D, and the inner diameter of the capillary die and / or the slit die installed in the viscosity measuring unit is set to d, and the slit length and the slit width are set to B and H respectively. k , where k is a natural number, the injection speed V is calculated based on the following formula (1) or formula (2): k , the injection speed V within the specified range among the calculated injection speeds k The value of is automatically set as the injection speed during viscosity measurement. [Number 1] [Number 2] 2. The injection molding machine according to claim 1, wherein: The viscosity measuring unit comprises: The capillary die and / or the slit die; a measuring cylinder, on which the capillary die and / or the slit die are installed; and The pressure sensor measures the pressure of the molding material flowing in the measuring cylinder.

3. The injection molding machine according to claim 2, wherein: The viscosity measuring unit is configured to be capable of mounting two or more dies having different specifications from each other.

4. The injection molding machine according to claim 1, Also includes a display device, The control device controls the injection speed V within the specified range. k The value is displayed on the display device.

5. The injection molding machine according to claim 2, wherein: The control device uses the injection speed V within the specified range k The injection drive device is operated at each value of and the measured value obtained from the pressure sensor is calculated and compared with the injection speed V k The value corresponding to the viscosity η of the molding material k .

6. The injection molding machine according to claim 5, Also includes a display device, The control device controls the injection speed V within the specified range. k The value of the viscosity η k The value is displayed on the display device.

7. The injection molding machine according to claim 6, wherein The control device controls the value γ representing the shearing speed k With the viscosity η k A graph showing the relationship between the values ​​of is plotted and displayed on the display device.

8. The injection molding machine according to claim 6, wherein The control device plots the value γ of the shear velocity by the Rabinovich correction k The corrected value is the same as the viscosity η corrected by Rabinovich k A graph showing the relationship between the values ​​obtained by calibration is displayed on the display device.

9. The injection molding machine according to any one of claims 6 to 8, wherein The viscosity measuring unit includes a temperature sensor for measuring the temperature of the molding material flowing in the measuring cylinder. The control device obtains the injection speed V within the specified range. k The injection drive device is operated at each value of and the actual measured value T of the temperature of the molding material obtained from the temperature sensor k , The control device then converts the measured value T of the temperature of the molding material into k displayed on the display device.

10. The injection molding machine according to claim 9, wherein The values ​​of the three or more shear rates γ k Selected from 1*10 1 sec -1 Above and 5*10 5 sec -1 The following range of values, where "*" indicates multiplication, The specified range of the injection speed is 0.05 mm·sec -1 Above and 200mm·sec -1 the following.

11. The injection molding machine according to claim 10, wherein Regarding the values ​​γ of the three or more shear rates k , R is set to a number greater than 1 and less than 5, and is R*10 1 sec -1 、R*10 2 sec -1 、R*10 3 sec -1 、R*10 4 sec -1 and R*10 5 sec -1 Five values ​​of .

12. The injection molding machine according to any one of claims 1 to 8, wherein The values ​​of the three or more shear rates γ k Selected from 1*10 1 sec -1 Above and 5*10 5 sec -1 The following range of values, where "*" indicates multiplication, The specified range of the injection speed is 0.05 mm·sec -1 Above and 200mm·sec -1 the following.

13. The injection molding machine according to claim 12, wherein Regarding the values ​​γ of the three or more shear rates k , R is set to a number greater than 1 and less than 5, and is R*10 1 sec -1 、R*10 2 sec -1 、R*10 3 sec -1 、R*10 4 sec -1 and R*10 5 sec -1 Five values ​​of .

14. The injection molding machine according to any one of claims 1 to 8, wherein The injection molding machine is a screw pre-plastic injection molding machine, The injection axis is a plunger.

15. The injection molding machine according to any one of claims 1 to 8, wherein The injection molding machine is an inline screw injection molding machine, The injection shaft is an inline screw.

16. A viscosity determination method comprising: At the injection speed V k wherein k is a natural number, and a step of causing a molding material to flow from an injection cylinder of an injection molding machine through a measuring cylinder of a viscosity measuring unit having a pressure sensor, and in a capillary or a slit of a mold mounted on the measuring cylinder; A step of acquiring a pressure value of the molding material flowing in the measuring cylinder by the pressure sensor; and The pressure value is used to calculate the injection speed V k The corresponding viscosity η k The process, The step of causing the molding material to flow includes calculating, by the control device of the injection molding machine, based on the following formula (1) or formula (2), the values ​​γ of the three or more shear speeds that are set in advance. k Corresponding injection speed V k The injection speed V in the specified range is calculated. k The value of is automatically set as the injection speed process during viscosity measurement. In the following formulas (1) and (2), D represents the inner diameter of the injection cylinder or the outer diameter of the injection shaft in the injection cylinder, d represents the inner diameter of the capillary, B and H represent the length and width of the slit, respectively. [Number 1] [Number 2] 17. The viscosity measuring method according to claim 16, wherein The injection speed V is automatically set k In the process, the values ​​of the three or more shear rates γ k Selected from 1*10 1 sec -1 Above and 5*10 5 sec -1 The values ​​in the following range, where "*" indicates multiplication, the specified range of the injection speed is 0.05 mm·sec -1 Above and 200mm·sec -1 the following.

18. The viscosity measuring method according to claim 17, wherein Regarding the values ​​γ of the three or more shear rates k , R is set to a number greater than 1 and less than 5, and is R*10 1 sec -1 、R*10 2 sec -1 、R*10 3 sec -1 、R*10 4 sec -1 and R*10 5 sec -1 Five values ​​of .

19. The viscosity measuring method according to any one of claims 16 to 18, wherein The step of acquiring the pressure value includes the step of switching two or more dies that are respectively the introduction destinations of the molding material through the measuring cylinder and acquiring the pressure values ​​individually.

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