Injection molding machine and fluidity measurement method

Abstract

To provide an injection molding machine that allows for easier measurement of the melt flow rate using the mechanism of the injection molding machine. [Solution] The injection molding machine comprises an injection unit, a measuring unit 5, a position sensor, a pressure sensor, and a control device. The measuring unit 5 includes a measuring cylinder, a die 62 having a die hole 621, a purge opening 63 provided in the measuring cylinder, and a flow path switching pin that switches the destination of the molding material discharge to either the die 62 or the purge opening 63. The control device is configured to advance the plunger so that the pressure of the molding material matches the set test load, discharge the molding material from the die hole 621, and calculate the melt flow rate.

Description

[Technical Field]

[0001] This invention relates to an injection molding machine and a method for measuring fluidity using an injection molding machine. [Background technology]

[0002] There is a demand for understanding the properties of molding materials used in injection molding. Understanding the properties of molding materials can be useful, for example, in determining molding conditions or in quality control. Parameters that indicate the properties of molding materials include viscosity and fluidity.

[0003] Patent documents 1 and 2 disclose a viscosity measuring unit that can be attached to an injection molding machine in place of a nozzle. This device allows the injection molding machine's mechanism to be used for viscosity measurement, enabling viscosity measurement equivalent to that of a capillary rheometer in an environment closer to actual injection molding. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 7328431 [Patent Document 2] Patent No. 7560623 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Depending on the type of molding material, fluidity may be a more suitable parameter for describing its properties than viscosity. For example, when comparing and analyzing molding materials with high pressure dependence, it is more appropriate to compare them based on fluidity.

[0006] One indicator of fluidity is the melt flow rate. More specifically, the melt flow rate is expressed as the melt mass flow rate (MFR) [g / 10min] or melt volume flow rate (MVR) [cm].3 It is expressed as [ / 10min]. Normally, a dedicated measuring device called an extrusion plastometer is used to measure the melt flow rate, but extrusion plastometers are relatively expensive and are not widely used by injection molding machine users. In addition, it is necessary to manually fill the cylinder with molding material, making the measurement time-consuming. Standard methods for measuring the melt flow rate are specified in JIS K 7210-1:2014 (ISO 1133-1:2011) and JIS K 7210-2:2014 (ISO 1133-2:2011).

[0007] This invention has been made in view of these circumstances, and aims to provide an injection molding machine and a fluidity measurement method that can more easily measure the melt flow rate using the mechanism of the injection molding machine. [Means for solving the problem]

[0008] According to the present invention, an injection molding machine is provided, comprising: an injection unit for extruding and injecting a molding material with an injection shaft; a measuring unit attached to the injection unit; a position sensor for measuring the position of the injection shaft; a pressure sensor for measuring the pressure of the molding material; and a control device. The measuring unit includes a measuring cylinder attached to the injection unit through which the molding material injected by the injection unit flows; a die attached to the measuring cylinder having a die hole configured to allow the molding material to flow; a purge opening provided in the measuring cylinder having a larger cross-sectional area than the die hole and configured to allow the molding material to flow; and a flow path switching pin for selectively switching the destination of the molding material discharge to either the die or the purge opening. The control device is configured to weigh the molding material when instructed to start measurement, advance the injection shaft so that the pressure of the molding material matches a set test load, discharge the molding material from the die hole, and calculate the melt flow rate based on one of the following: the mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined intervals; the distance the injection shaft moves in a predetermined time; or the time required for the injection shaft to move the predetermined distance. [Effects of the Invention]

[0009] According to the injection molding machine of the present invention, the melt flow rate can be measured by using the mechanism of the injection molding machine. In particular, since the preparation and measurement can be easily performed, the burden on the operator who measures the melt flow rate can be reduced.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic configuration diagram of an injection molding machine according to an embodiment of the present invention in a state where an injection nozzle is attached. [Figure 2] It is a schematic configuration diagram of an injection molding machine according to an embodiment of the present invention in a state where a measurement unit is attached. [Figure 3] It is a perspective view of the measurement unit seen from above. [Figure 4] It is a perspective view of the measurement unit seen from below. [Figure 5] It is a side sectional view of the measurement unit. [Figure 6] It is a view in the direction of arrow VI-VI of the measurement unit and is a front sectional view. [Figure 7] It is a sectional view of the die. [Figure 8] It is a block diagram of the control device. [[ID=3�]] [Figure 9] It is an example of a GUI when measuring the melt mass flow rate. [Figure 10] It is an example of a GUI when measuring the melt volume flow rate. [Figure 11] It is an example of a flowchart when measuring the melt mass flow rate. [Figure 12] It is an example of a flowchart when measuring the melt volume flow rate.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, for the purpose of improving visibility and the like, some components may be omitted from illustration. The various modifications described below can be implemented in any combination.

[0012] The injection molding machine of the present embodiment includes an injection unit 1 that extrudes and injects a molding material with an injection shaft, a clamping unit (not shown) that opens and closes and clamps a mold (not shown), and a control device 7 that controls the injection unit 1 and the clamping unit. When performing injection molding, the injection unit 1 plasticizes the molding material, measures a predetermined amount, and then injects it from the injection nozzle 46. The clamping unit holds the mold and is configured to be able to open, close, and clamp the mold. In injection molding, when the molding material is injected, the clamping unit closes the mold and applies a clamping force of a predetermined pressure to the mold. After the molding material injected into the cavity of the mold from the injection nozzle 46 is cooled and becomes a molded product, the clamping unit opens the mold, discharges the molded product, and closes the mold again. As the clamping unit, a well-known configuration such as a direct pressure type or a toggle type can be adopted.

[0013] In this specification, a material that can be injected by an injection molding machine is broadly referred to as a molding material, and in addition to materials mainly made of resin, it also includes MIM materials in which resin is added as a binder to metal powder and CIM materials in which resin is added as a binder to ceramic powder. Further, hereinafter, an injection molding machine using a thermoplastic molding material will be described as an example, but the present invention is also applicable to an injection molding machine using a thermosetting molding material. Thermosetting molding materials include LIM materials that are thermosetting liquid materials.

[0014] The injection molding machine of this embodiment is a so-called screw pre-plasticized injection molding machine in which the plasticizing unit 2 and the injection unit 4 are configured as separate components. As shown in Figure 1, the injection unit 1 comprises the plasticizing unit 2, the junction 3, and the injection unit 4. In Figure 1, some of the components are shown in a cross-sectional view. Hereafter, the left side in Figure 1, i.e., the side from which the molding material is injected, will be referred to as the front. The right side in Figure 1, i.e., the side from which the molding material is supplied, will be referred to as the rear.

[0015] The plasticizing unit 2 comprises a plasticizing cylinder 21, a plasticizing screw 23, a check valve 25, a plasticizing screw drive unit 27, and a heater 29. The plasticizing cylinder 21 is a hollow cylindrical body heated to a predetermined temperature by a heater 29, such as a band heater. A material inlet 211 is formed at the rear end of the plasticizing cylinder 21, through which the molding material is supplied. The plasticizing screw 23 is rotatably mounted inside the plasticizing cylinder 21. The plasticizing screw 23 moves the molding material supplied into the plasticizing cylinder 21 from the material inlet 211 forward, melting it with heat from the heater 29 and through shear heat. The check valve 25 is an arbitrary actuator that advances the plasticizing screw 23, such as a fluid pressure cylinder or an electric cylinder. The check valve 25 advances the plasticizing screw 23 when metering is complete to block the flow path and prevent backflow of the molding material during injection. The plasticizing screw drive device 27 is any actuator that rotates the plasticizing screw 23, such as a hydraulic motor or an electric motor.

[0016] Junction 3 connects the plasticizing cylinder 21 of the plasticizing section 2 and the injection cylinder 41 of the injection section 4. Junction 3 may be heated to a predetermined temperature by a heater.

[0017] The injection unit 4 comprises an injection cylinder 41, a plunger 42 which is the injection shaft, a plunger drive device 43, a position sensor 441, a pressure sensor 442, a nozzle cylinder 45, an injection nozzle 46, and heaters 47 and 48.

[0018] The injection cylinder 41 is a hollow cylindrical body heated to a predetermined temperature by a heater 47, such as a band heater. The molding material sent from the plasticizing cylinder 21 is stored in the injection cylinder 41. The plunger 42 is a substantially cylindrical member that is provided within the injection cylinder 41 so as to be able to move back and forth. In a screw pre-plasticized injection molding machine, the plunger 42 corresponds to the injection shaft for pushing out and injecting the molding material. The plunger drive device 43 is any actuator that moves the plunger 42 forward and backward, such as a hydraulic cylinder or an electric cylinder. The plunger 42 and the piston rod of the plunger drive device 43 are connected via a coupling.

[0019] The position sensor 441 is a sensor that reads the position of the plunger 42. The position sensor 441 may be any sensor that can measure the position of the plunger 42 directly or indirectly, such as a linear scale. When the plunger drive device 43 is an electric cylinder, the position sensor 441 may be a rotary encoder.

[0020] The pressure sensor 442 is a sensor that reads the pressure applied to the plunger 42. The pressure sensor 442 may be any sensor capable of directly or indirectly measuring the pressure applied to the plunger 42, for example, a load cell installed between the plunger 42 and the piston rod. When the plunger drive device 43 is a hydraulic cylinder, the pressure sensor 442 may be a hydraulic pressure gauge. When the plunger drive device 43 is an electric cylinder, the position sensor 441 may be a motor current meter or torque meter.

[0021] The nozzle cylinder 45 is a cylindrical body mounted in front of the injection cylinder 41 and heated to a predetermined temperature by a heater 47 such as a band heater. The nozzle cylinder 45 has a supply passage connecting the junction 3 and the injection cylinder 41, and a discharge passage connecting the injection cylinder 41 and the injection nozzle 46. A nozzle mounting hole 451 is formed on the front surface of the nozzle cylinder 45, to which the injection nozzle 46 can be attached. More specifically, a female thread is formed on the inner wall of the nozzle mounting hole 451, which engages with a male thread formed on the rear end of the injection nozzle 46. The injection nozzle 46 is attached to the nozzle cylinder 45 during injection molding. The injection nozzle 46 is heated to a predetermined temperature by a heater 48 such as a coil heater.

[0022] The molding material melted by the plasticizer 2 is sent through the junction 3 and nozzle cylinder 45 to the injection cylinder 41. In the injection cylinder 41, the molding material is stored in front of the plunger 42, and the desired amount of molding material is metered. After metering, backflow to the plasticizer 2 is prevented by the check valve 25, and then the plunger 42 is advanced, sending 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.

[0023] Here, the measurement unit 5 of this embodiment will be described. The measurement unit 5 is attached to the injection unit 1 when measuring the melt flow rate of the molding material. The mounting position of the measurement unit 5 can be in front of the injection cylinder 41, but from the viewpoint of workability, it is preferable to attach it in place of the injection nozzle 46, as shown in Figure 2. That is, the injection nozzle 46 can be removed from the nozzle cylinder 45, and the measurement cylinder 50 of the measurement unit 5 can be attached to the nozzle mounting hole 451 of the nozzle cylinder 45. A detailed method for attaching the measurement unit 5 will be described later.

[0024] As shown in Figures 3 to 6, the measurement unit 5 of this embodiment includes a measurement cylinder 50 to which a pressure sensor 61 is attached, a die 62, a purge opening 63, a flow path switching pin 64, a fixing plate 65, a positioning rod 66, and heaters 67, 68.

[0025] The measuring cylinder 50 is attached to the injection section 4 of the injection unit 1, and the molding material injected by the injection section 4 flows through it. The measuring cylinder 50 in this embodiment includes a first cylinder 51 and a second cylinder 52, and the first cylinder 51 and the second cylinder 52 are configured to be separable. The first cylinder 51 and the second cylinder 52 are fastened together by a cover nut 53, which serves as a fastening means. A heater 67, which is a band heater, is wound around the cover nut 53.

[0026] The first cylinder 51 has a flow path 511, a mounting portion 512, and a flange 513. The flow path 511 is formed to penetrate axially into the interior of the first cylinder 51 and is connected to the discharge flow path of the nozzle cylinder 45. The mounting portion 512 is provided at the rear end of the first cylinder 51 and has a male thread that screws into the female thread formed in the nozzle mounting hole 451. The flange 513 is provided at the front end of the first cylinder 51 and abuts against the cover nut 53.

[0027] The second cylinder 52 has a flow path 521, a flow path switching pin mounting hole 522, a flow path 523, a die mounting hole 524, a pressure sensor mounting hole 525, a positioning rod insertion hole 526, and a heater mounting hole 527. In addition, a male thread is formed at the rear end of the second cylinder 52, which engages with the female thread formed in the inner hole of the cover nut 53.

[0028] The flow path 521 is formed axially inside the second cylinder 52 and is connected to the flow path 511 and the flow path switching pin mounting hole 522. The flow path switching pin mounting hole 522 is a hole formed on the front surface of the second cylinder 52. A flow path switching pin 64 is rotatably inserted into the flow path switching pin mounting hole 522. The flow path 523 is formed radially inside the second cylinder 52 and is connected to the flow path switching pin mounting hole 522 and the die mounting hole 524. In this embodiment, two flow paths 523 are formed.

[0029] The die mounting hole 524 is a hole formed on the side surface of the second cylinder 52. In this embodiment, two die mounting holes 524 are provided, with the die 62 fixed to one and the other functioning as a purge opening 63. In other words, in this embodiment, the die mounting hole 524 and the purge opening 63 are interchangeable components, but it is not essential that the die 62 can be mounted in the purge opening 63. To put it another way, it is sufficient that at least one of the holes communicating with the flow path 523 can be used to mount the die 62. In this embodiment, female threads are formed on the inner wall of the die mounting hole 524, and male threads are formed on the outer circumference of the die 62, allowing for easy attachment and detachment by screwing them together.

[0030] The pressure sensor mounting hole 525 is a hole formed through the side of the second cylinder 52 and the flow path 521. A pressure sensor 61 is mounted in the pressure sensor mounting hole 525. The positioning rod insertion hole 526 is a hole formed through the side of the second cylinder 52 and the flow path switching pin mounting hole 522. A positioning rod 66 is inserted through the positioning rod insertion hole 526. The heater mounting hole 527 is a hole formed in the second cylinder 52 through which a cartridge heater 68 is inserted.

[0031] The pressure sensor 61 is a pressure transducer inserted into the pressure sensor mounting hole 525 of the measuring cylinder 50 and measures the pressure of the molding material inside the measuring cylinder 50. More specifically, in this embodiment, the pressure sensor 61 measures the pressure of the molding material flowing through the flow path 521 of the second cylinder 52.

[0032] As described later, when discharging the molding material from the die 62 during melt flow rate measurement, the plunger 42 is advanced with a set test load. At this time, i.e., during measurement, feedback control is performed based on the measured pressure of the molding material so that the pressure of the molding material and the test load match. The test load, i.e., the pressure of the molding material during melt flow rate measurement, is very low compared to the pressure of the molding material that occurs during normal injection molding. Therefore, the pressure sensor 442 of the injection unit 4, which is intended for use in pressure detection during injection molding, may not be able to detect the pressure during melt flow rate measurement with high accuracy. Thus, by providing a pressure sensor 61 suitable for low-pressure measurement in the measuring cylinder 50 and referring to the detected value of the pressure sensor 61 during melt flow rate measurement, the feedback accuracy of the plunger 42 can be made more accurate, and consequently the accuracy of melt flow rate measurement can be improved. The measurable range of the pressure sensor 61 is preferably a low-pressure range, for example, greater than 0 MPa and less than or equal to about 20 MPa. However, if an acceptable measurement accuracy can be obtained even when using the pressure sensor 442, the pressure sensor 61 may be omitted and the pressure sensor 442 may be used for feedback control when measuring the melt flow rate.

[0033] As shown in Figure 7, a die 62 having a die bore 621 configured to allow the molding material to flow is attached to the measuring cylinder 50. When performing measurements equivalent to those specified in JIS K 7210-1:2014 (ISO 1133-1:2011) and JIS K 7210-2:2014 (ISO 1133-2:2011), the standard die or half-size die described in the said standard is used as the die 62. A standard die is a die 62 having a die bore 621 with an effective length L of 8,000 mm and a bore diameter φ of 2,095 mm. A half-size die is a die 62 having a die bore 621 with an effective length L of 4,000 mm and a bore diameter φ of 1,050 mm. The die bore 621 is located at the end of the die 62, and the molding material sent via the flow path switching pin 64 flows through it. The flow channels in die 62 other than die holes 621 only need to have a sufficient cross-sectional area so as not to hinder the flow of the molding material.

[0034] The purge opening 63 is a hole provided in the measuring cylinder 50, configured to allow the molding material to flow through it. The purge opening 63 has a sufficient cross-sectional area so as not to hinder the flow of the molding material, and at least the cross-sectional area of ​​the purge opening 63 is larger than the cross-sectional area of ​​the die hole 621. The diameter of the purge opening 63 is, for example, about 4.0 mm or more and about 6.0 mm or less. In order to measure the melt flow rate, as a preliminary step, the existing molding material present in the injection unit 1 is replaced with the molding material to be measured, and a purging operation is performed to discharge the molding material until the condition stabilizes. Since the die hole 621 of the die 62 has a very small diameter, attempting to discharge the molding material from the die hole 621 during purging takes a very long time and places a heavy load on the equipment. Therefore, by discharging the molding material from the purge opening 63 during purging, purging can be performed efficiently.

[0035] In this embodiment, as shown in Figure 6, the die mounting hole 524, which has nothing attached to it, is used as the purge opening 63 as is. However, a cylindrical body having a sufficiently large through hole may be attached to the die mounting hole 524, and this through hole may be used as the purge opening 63. The cylindrical body may be configured to be screwable with the die mounting hole 524. By using a cylindrical body, it is possible to prevent the molding material discharged during purging from adhering to the inner wall of the die mounting hole 524.

[0036] The flow path switching pin 64 selectively switches the discharge destination of the molding material supplied from the flow paths 511 and 521 to either the die 62 or the purge opening 63. In this embodiment, the flow path switching pin 64 is a cylindrical member rotatably fitted into the flow path switching pin mounting hole 522, and has a flow path 641, a tool hole 642, and a recess 643. The flow path 641 is bent at 90° in the middle, with the inlet side connected to the flow path 521 and the outlet side connected to one of the flow paths 523. By rotating the flow path switching pin 64, the flow path 523 connected to the flow path 641 can be switched. The tool hole 642 is formed on the front surface of the flow path switching pin 64 and is a hole that fits into a tool of any shape. In this embodiment, a hexagonal hole that fits into a hex wrench is formed as the tool hole 642. By fitting a tool into the tool hole 642, the flow path switching pin 64 can be rotated. The recess 643 is a hole formed on the side of the flow path switching pin 64, and is positioned to connect with one of the positioning rod insertion holes 526 when the flow path 641 is connected to one of the flow paths 523. In other words, in this embodiment, the flow path switching pin 64 is located on the central axis of the second cylinder 52, and when the outlet side of the flow path 641 is connected to the flow path 523, the recess 643 and the positioning rod insertion hole 526 are located on opposite sides of the central axis.

[0037] The fixing plate 65 is a plate-shaped member that is fixed to the front surface of the second cylinder 52 with bolts or the like, and contacts the flow path switching pin 64 to prevent the flow path switching pin 64 from falling out. An opening is formed in the center of the fixing plate 65 so as not to cover the tool hole 642.

[0038] The positioning rod 66 has a rod-shaped member that is inserted into the positioning rod insertion hole 526. The positioning rod 66 is inserted into the positioning rod insertion hole 526 after the flow path to be used is selected by rotating the flow path switching pin 64. As a result, the tip of the positioning rod 66 fits into the recess 643, accurately positioning the flow path switching pin 64 and preventing accidental rotation.

[0039] In this embodiment, the flow path switching pin 64 is configured to be manually rotatable using a tool, but it may also be configured to be automatically rotatable by any actuator such as a fluid pressure cylinder or an electric motor. In this case, the switching of the die by the flow path switching pin 64 may be controlled by the control device 7.

[0040] In order to prevent the molding material discharged from the die 62 and the purge opening 63 from scattering, it is preferable that the measuring cylinder 50 be attached to the injection unit 1 so that the die 62 and the purge opening 63 face downward. Specifically, the measuring cylinder 50 is attached by the following procedure. First, the cover nut 53 is inserted through the first cylinder 51 and the mounting portion 512 of the first cylinder 51 is screwed into the nozzle mounting hole of the nozzle cylinder 45. Next, the first cylinder 51 and the second cylinder 52 are engaged and positioned so that the die mounting hole 524 of the second cylinder 52 faces downward. In this state, the cover nut 53 is screwed onto the second cylinder 52 and the cover nut 53 is rotated until the wall surface 531 of the cover nut 53 contacts the flange 513 of the first cylinder 51. In this way, the first cylinder 51 and the second cylinder 52 are fastened together.

[0041] Each component attached to the second cylinder 52 may be attached before or after fastening the first cylinder 51 and the second cylinder 52. In this embodiment, the first cylinder 51 and the second cylinder 52 are fastened together with a cover nut 53, but other fastening means such as bolts may be used.

[0042] After fastening the first cylinder 51 and the second cylinder 52 using the procedure described above, the first cylinder 51 is aligned so that when it is screwed into the nozzle mounting hole 451, the die 62 and the purge opening 63 face downwards. Therefore, once the first cylinder 51 and the second cylinder 52 have been fastened using the procedure described above, they may be attached to the nozzle cylinder 45 in their assembled state. However, if the injection molding machine to which they are attached is changed, the same alignment procedure will need to be repeated.

[0043] In order to ensure that the die 62 and the purge opening 63 face downwards, it is desirable that the angle between the line passing through the center of the die 62 and the line passing through the center of the purge opening 63 in a front view be 40° or less.

[0044] Here, the control device 7 of this embodiment will be described. The control device 7 controls the injection unit 1 and the clamping unit, and is configured to calculate the melt flow rate based on one of the following: the mass of a sample obtained by cutting the molding material discharged from the die hole 621 at predetermined intervals, the distance the plunger 42 moves in a predetermined time, or the time required for the plunger 42 to move the predetermined distance. Based on the mass of a sample obtained by cutting the molding material discharged from the die hole 621 at predetermined intervals, the melt mass flow rate can be calculated directly. Based on the distance the plunger 42 moves in a predetermined time or the time required for the plunger 42 to move the predetermined distance, the melt volume flow rate can be calculated directly. Furthermore, it is possible to convert between the melt mass flow rate and the melt volume flow rate based on the density of the molding material.

[0045] The control device 7 may be configured by any combination of hardware and software, and for example, as shown in Figure 8, it comprises an arithmetic unit 71, a storage device 72, an input device 73, a display device 74, a timer 75, and a sound output device 76. The arithmetic unit 71 is any arithmetic circuit such as a CPU, and performs various calculations for controlling each part, as well as calculations related to melt flow rate calculation. The storage device 72 may be configured by any combination of RAM, ROM, and auxiliary storage devices, and stores data necessary for calculations by the arithmetic unit 71. The storage device 72 may also store standard test conditions for major molding materials. The input device 73 and the display device 74 may each be standalone devices, or they may include a device that serves both purposes, such as a touch panel. In this embodiment, an operation panel equipped with a touch panel and input keys is provided as a device that serves as both the input device 73 and the display device 74. The timer 75 can measure the time used for various controls.

[0046] When measuring the melt mass flow rate, a notification means may be provided to inform the operator of the timing to cut the molding material discharged from the die hole 621. In this embodiment, the notification means consists of a display device 74 and a sound output device 76. That is, the display device 74 displays a message or image to inform the operator of the timing to cut the molding material. The sound output device 76 outputs a buzzer sound or voice to inform the operator of the timing to cut the molding material. The notification means is not limited to these devices and may include other devices such as lamps, or one or more devices may be used in any combination.

[0047] The control device 7 controls the plasticizing screw drive device 27, check valve 25, and plunger drive device 43 of the injection unit 1 during injection molding and melt flow rate measurement to melt, meter, and inject the molding material.

[0048] The control device 7 controls heaters 29, 47, 48, 67, and 68 to heat the plasticizing cylinder 21, injection cylinder 41, nozzle cylinder 45, injection nozzle 46, and measuring cylinder 50 to the desired temperature. However, heaters 67 and 68 are not used during injection molding. Also, heater 48 is not used during melt flow rate measurement. Temperature sensors such as thermocouples may be provided in each part, and heaters 29, 47, 48, 67, and 68 may be feedback controlled based on the measured temperature.

[0049] Figures 9 and 10 show an example of the GUI displayed on the display device 74 during melt flow rate measurement. The GUI for melt flow rate measurement can be accessed from the GUI for normal injection molding. The injection molding machine in this embodiment is configured to be switchable between an MFR mode, which directly measures the melt mass flow rate, and an MVR mode, which directly measures the melt volume flow rate.

[0050] The GUI for MFR mode, as shown in Figure 9, includes, for example, a test condition input unit 80, a measurement start button 81, a message display unit 82, a measurement result input unit 83, a calculation start button 84, a calculation result display unit 86, a data save button 87, a data display unit 88, and an exit button 89. The GUI for MVR mode, as shown in Figure 10, includes, for example, a test condition input unit 80, a measurement start button 81, a calculation start button 84, a measurement result display unit 85, a calculation result display unit 86, a data save button 87, a data display unit 88, and an exit button 89.

[0051] The test condition input unit 80 includes a button for switching between MFR mode and MVR mode, an input field for the measurement name, a button for selecting the die 62 to be used, and an input field for the test conditions. The die 62 may be selected from a standard die or a half-size die. Standard test conditions are known for major molding materials. Therefore, by selecting the type of molding material (resin type), the standard test conditions may be automatically entered into the test condition input field. The automatically entered test conditions may be changed as needed. The operator can also manually enter the test conditions.

[0052] The test conditions for MFR mode are: • Test load [kgf]: The set pressure to advance plunger 42. • Test temperature [°C]: Set temperature of injection unit 1 and measuring cylinder 50 • Sample cutting time [sec]: Time interval for cutting the molding material ejected from die hole 621. • Number of measurements [times]: The number of times the molded material is cut to obtain a sample. It holds.

[0053] When measuring the distance the plunger 42 moves in a predetermined time, the test conditions for MVR mode are: • Test load [kgf]: The set pressure to advance plunger 42. • Test temperature [°C]: Set temperature of injection unit 1 and measuring cylinder 50 • Movement time [sec]: Time to advance plunger 42 • Number of measurements [times]: The number of times the travel distance of plunger 42 is measured. It holds.

[0054] When measuring the time required for the plunger 42 to travel a predetermined distance, the test conditions in MVR mode are: • Test load [kgf]: The set pressure to advance plunger 42. • Test temperature [°C]: Set temperature of injection unit 1 and measuring cylinder 50 • Distance traveled [mm]: The distance the plunger 42 is advanced. • Number of measurements [times]: The number of times the travel time of plunger 42 is measured. It holds.

[0055] In this embodiment, the melt volume flow rate measured in MVR mode is configured to be converted to a melt mass flow rate and displayed. Therefore, in this embodiment, the test condition input unit 80 in MVR mode is configured ·Density [g / cm 3 ]: Density of the molding material at the test temperature It also has an input field for density. Furthermore, the device may be configured to convert the melt mass flow rate measured in MFR mode to a melt volume flow rate and display it; in that case, an input field for density may also be provided in MFR mode.

[0056] When the measurement start button 81 is pressed, the control device 7 receives the instruction to start measurement, weighs the molding material, advances the plunger 42 so that the pressure of the molding material matches the set test load, and discharges the molding material from the die hole 621 of the die 62.

[0057] In this embodiment, when measuring the melt mass flow rate in MFR mode, the operator manually cuts the sample. The timing for cutting the molding material is communicated to the operator via a notification means. The message display unit 82 constitutes the notification means in the display device 74. However, a cutting device for cutting the molding material discharged from the die hole 621 may be provided, and the sample may be cut automatically. In this case, the notification means may be omitted.

[0058] In the MFR mode of this embodiment, the operator measures the mass of the sample using a mass scale and manually inputs the measurement result into the measurement result input unit 83. Then, when the calculation start button 84 is pressed, the calculated melt mass flow rate value is displayed on the calculation result display unit 86. However, a mass scale connected to the control device 7 may be provided, and the sample mass may be automatically input.

[0059] In the MVR mode of this embodiment, the distance the plunger 42 travels in a predetermined time is displayed on the measurement result display unit 85, and the melt volume flow rate calculated based on that distance is displayed on the calculation result display unit 86. Alternatively, the time required for the plunger 42 to travel the predetermined distance may be displayed on the measurement result display unit 85, and the melt volume flow rate calculated based on that time may be displayed on the calculation result display unit 86. In this embodiment, the melt mass flow rate calculated based on the melt volume flow rate and density is also displayed on the measurement result display unit 85.

[0060] When the data save button 87 is pressed, the measurement data is saved and displayed in a list on the data display unit 88. The measurement data may include information such as the measurement date, the measurement mode used, the measurement name, the type of die 62 used, the type of molding material, the test conditions, and the measurement results. The measurement data may be saved in the storage device 72 of the control device 7, or in an external storage medium 77 such as a portable storage medium like flash memory. Once the measurement data is saved in the storage device 72 of the control device 7, it may be output to the external storage medium 77. Past measurement data saved in the storage device 72 or the external storage medium 77 may be read and displayed on the data display unit 88. Each item of the measurement data displayed on the data display unit 88 may be arbitrarily switched on or off. The system may be configured to allow the addition of supplementary information to the measurement data.

[0061] When the exit button 89 is pressed, the GUI for measuring the melt flow rate is closed and the system switches to the GUI for normal injection molding.

[0062] Here, an example of a fluidity measurement method using the injection molding machine of this embodiment will be described.

[0063] Figure 11 shows an example flowchart for calculating the melt mass flow rate using the MFR mode.

[0064] First, preparations are made before the measurement (S11). The preparations may include the following steps. The operator sets the test conditions necessary for the measurement as described above. The injection unit 1, including the plasticizer 2 and the injection unit 4, and the measuring cylinder 50 are heated to a predetermined temperature, i.e., the test temperature. After the heating of each part is complete, the molding material to be measured is introduced into the material input port 211 and the molding material is purged. During purging, the discharge destination of the molding material by the flow path switching pin 64 is set to the purge opening 63, and the molding material sent from the plasticizer 2 and the injection unit 4 passes through the measuring cylinder 50 and is discharged from the purge opening 63. There are two types of purging: a drawing purge performed with the plunger 42 fixed, and a metering purge performed with metering in the injection cylinder 41 and injection by the plunger 42. Either one of these may be performed, or a combination of both may be performed. After purging is complete, the flow path switching pin 64 is rotated to switch the discharge destination of the molding material to the die 62.

[0065] Since the state of the molding material can change if it remains in the injection molding machine for a long time, it is desirable to start measurement immediately after purging for high-precision measurement. With the injection molding machine of this embodiment, after purging, the discharge destination of the molding material can be switched from the purge opening 63 to the die 62 using the flow path switching pin 64, eliminating the need for extensive work and allowing for a quick transition to measurement.

[0066] When the measurement start button 81 is pressed and measurement is initiated, the molding material is weighed (S12). The plasticizing screw 23 rotates, melting the molding material and sending it to the injection cylinder 41. The molding material sent to the injection cylinder 41 is stored in front of the plunger 42, pushing it down. When the plunger 42 reaches a predetermined position, the weighing is considered complete, the plasticizing screw 23 stops, and the check valve 25 prevents backflow. The weighed value only needs to be a sufficient amount for measurement; for example, the maximum amount that can be weighed in the injection unit 4 may be weighed. Note that in extrusion-type plastometers, it is necessary to compress the molding material with a rod to remove gas after filling the cylinder, but with weighing using an injection molding machine as in this embodiment, weighing can be performed with almost no air being drawn in, so this operation is generally unnecessary.

[0067] Next, the plunger 42 begins to move and advances to the measurement start position (S13). The plunger 42 is feedback controlled based on the pressure measured by the pressure sensor 61 so that the pressure of the molding material matches the set test load. As the plunger 42 advances, molten molding material is discharged from the die hole 621 of the die 62. The plunger 42 advances while applying a predetermined test load to the molding material. The test starts when the plunger 42 reaches the predetermined measurement start position.

[0068] The notification means informs the operator that the plunger 42 has reached the measurement start position, and the operator then cuts the molding material being discharged from the die hole 621 (S14). The molding material cut off at this time is not used for measurement and may be discarded.

[0069] The plunger 42 continues to advance, and each time the set sample cutting time has elapsed, the notification means informs the operator that it is time to cut the molding material. The operator then cuts the molding material being discharged from the die hole 621 to obtain a sample. In other words, the process of advancing the plunger 42 for a predetermined time and cutting the molding material to obtain a sample is repeated for the set number of measurements (S15-S17).

[0070] When cutting the molding material, the movement of the plunger 42 may be temporarily paused. That is, the control device 7 may temporarily pause the plunger 42 at the start of the test and when taking a sample. The plunger 42 may resume moving forward after a predetermined time has elapsed, or it may resume moving forward based on instructions from the operator.

[0071] The operator measures the mass of the sample and inputs the measured mass into the measurement result input unit 83 of the control device 7 (S18-S19). When the calculation start button 84 is pressed, the control device 7 calculates the melt mass flow rate based on the following formula and displays it on the calculation result display unit 86 (S20). Here, MFR [g / 10min]: Meltmass Flow Rate m n [g]: Mass of the sample after the nth measurement. t[sec]: Sample cutting time n[times]: Number of measurements Let's assume that.

[0072]

number

[0073] Figure 12 shows an example flowchart for calculating the melt volume flow rate using MVR mode.

[0074] The same procedure as when calculating the melt mass flow rate is followed: preliminary preparation (S31), weighing of the molding material (S32), and advancement of the plunger 42 to the weighing start position (S33). Subsequent flow branches depending on whether the measurement target is the distance the plunger 42 moves in a predetermined time or the time required for the plunger 42 to move a predetermined distance (S34).

[0075] The flow for measuring the distance the plunger 42 moves is as follows: After each set time has elapsed, the position of the plunger 42 at that time is read and the distance moved is calculated. That is, the distance the plunger 42 moves in a predetermined time is measured and repeated for a set number of measurements (S35A-S36A). The control device 7 calculates the melt volume flow rate based on the following formula and displays it on the calculation result display unit 86 (S37). Here, MVR[cm 3 [10 min]: Melt Volume Flow Rate A[cm 2 ]: Cross-sectional area of ​​plunger 42 l n [cm]: Distance traveled by plunger 42 on the nth step t[sec]: Travel time of plunger 42 n[times]: Number of measurements Let's assume that.

[0076]

number

[0077] The flow for measuring the time it takes for the plunger 42 to move is as follows: Each time the plunger 42 moves a distance set as the travel distance, the time required for that movement is calculated. That is, the measurement of the time required for the plunger 42 to move a predetermined distance is repeated for a set number of measurements (S35B-S36B). The control device 7 calculates the melt volume flow rate based on the following formula and displays it on the calculation result display unit 86 (S37). Here, MVR[cm 3 / 10 min]: Melt volume flow rate A [cm 2 : Cross-sectional area of plunger 42 l [cm]: Movement distance of plunger 42 t n [sec]: Movement time of plunger 42 for the nth time n [times]: Number of measurements Let it be so.

[0078]

Number

[0079] The melt volume flow rate may be converted to the melt mass flow rate and displayed on the calculation result display unit 86. The control device 7 can calculate the melt mass flow rate from the melt volume flow rate based on the following formula. Here, MFR [g / 10 min]: Melt mass flow rate MVR [cm 3 / 10 min]: Melt volume flow rate ρ [g / cm 3 : Density of the molding material at the test temperature Let it be so. Conversely, the melt mass flow rate may be converted to the melt volume flow rate and displayed on the calculation result display unit 86.

[0080]

Number

[0081] If the density is known, the information may be referred to, but it may be calculated based on the mass of the sample obtained by cutting the molding material discharged from the die hole 621 when the plunger 42 moves a predetermined distance. Specifically, the density can be calculated based on the following formula. Here, ρ [g / cm 3 ​​​​​​​2 ]: Cross-sectional area of ​​plunger 42 l[cm]: Distance traveled by plunger 42 n[times]: Number of measurements Let's assume that.

[0082]

number

[0083] The density may be calculated on the injection molding machine using the same equipment as when the melt flow rate was measured. In this case, the injection molding machine may be configured to display a GUI related to the density measurement mode on the display device 74. The operator may set the test conditions for the density measurement mode as follows: • Test load [kgf]: The set pressure to advance plunger 42. • Test temperature [°C]: Set temperature of injection unit 1 and measuring cylinder 50 • Distance traveled [mm]: The distance the plunger 42 is advanced. • Number of measurements [times]: The number of times the molded material is cut to obtain a sample. Enter the following. When measuring density, theoretically, the same test temperature and pressure as when measuring the melt flow rate later are required. However, since the test pressure is sufficiently low, it does not need to be practically the same. After weighing the molding material and moving the plunger 42 to the measurement start position, the molding material is cut to obtain a sample each time it moves the distance set as the movement distance, following the same procedure as for measurement in MFR mode. Based on the mass of the weighed sample, the control device 7 calculates and displays the density from the above formula.

[0084] The injection molding machine of this embodiment allows for the measurement of the melt flow rate using the mechanism of the injection molding machine. Therefore, it is possible to measure the melt flow rate at a lower cost than preparing an extrusion-type plastometer. In addition, it has the advantage of reducing the workload on the operator compared to an extrusion-type plastometer, especially in that it requires less preparation time. Furthermore, viscosity measurements equivalent to those of an extrusion-type plastometer can be performed under conditions closer to actual injection molding.

[0085] The injection molding machine used to implement the fluidity measurement method of this embodiment may be a so-called inline screw type injection molding machine in which the plasticizing section 2 and the injection section 4 are integrated. The inline screw type injection molding machine includes a cylinder and a screw that is rotatable and reciprocable within the cylinder, serving as both the plasticizing section 2 and the injection section 4. In an inline screw type injection molding machine, the screw corresponds to the injection shaft. However, if the injection molding machine is a screw pre-plasticized injection molding machine equipped with a check valve 25 that advances the plasticizing screw 23 to prevent backflow, as in this embodiment, it offers superior stability and reproducibility in metering and injection compared to an inline screw type injection molding machine, allowing for more accurate measurement of the melt flow rate of the molding material.

[0086] As several examples have already been specifically shown, the present invention is not limited to the configuration of the embodiments shown in the drawings, and various modifications or applications are possible without departing from the technical spirit of the present invention. [Explanation of Symbols]

[0087] 1. Injection Unit 2 Plasticizing part 3 Junction 4 Injection part 42 plungers 441 Position Sensor 5. Measurement Unit 50 Measuring Cylinders 61 Pressure Sensor 62 Dies 621 Die hole 63 Purge opening 64 Pathway switching pins 7 Control device 74 Display device 76. Sound output device

Claims

1. An injection unit that extrudes and injects the molding material using an injection shaft, A measuring unit attached to the injection unit, A position sensor for measuring the position of the injection shaft, A pressure sensor for measuring the pressure of the molding material, A control device is provided, The aforementioned measuring unit is A measuring cylinder attached to the injection unit through which the molding material injected by the injection unit flows, A die attached to the measuring cylinder and having a die hole configured to allow the molding material to flow through, A purge opening is provided in the measuring cylinder, having a larger cross-sectional area than the die hole, and configured to allow the molding material to flow through it, The system includes a flow path switching pin that selectively switches the discharge destination of the molding material to either the die or the purge opening, An injection molding machine configured such that when instructed to start measurement, the control device weighs the molding material, advances the injection shaft so that the pressure of the molding material matches a set test load, discharges the molding material from the die hole, and calculates the melt flow rate based on one of the following: the mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined intervals, the distance the injection shaft moves in a predetermined time, or the time required for the injection shaft to move the predetermined distance.

2. The control device includes notification means for notifying the operator of the timing to cut the molding material discharged from the die hole. The injection molding machine according to claim 1, wherein the control device is configured to calculate the melt mass flow rate based on the mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined intervals.

3. The injection molding machine according to claim 2, wherein the notification means is a display device.

4. The injection molding machine according to claim 2, wherein the notification means is a sound output device.

5. The device further comprises a cutting device for cutting the molding material discharged from the die hole, The injection molding machine according to claim 1, wherein the control device is configured to calculate the melt mass flow rate based on the mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined intervals.

6. The injection molding machine according to claim 1, wherein the control device is configured to calculate the melt volume flow rate based on the distance the injection shaft moves in a predetermined time or the time required for the injection shaft to move a predetermined distance, and to calculate the melt mass flow rate based on the melt volume flow rate and the density of the molding material.

7. The injection molding machine according to claim 1, wherein the pressure sensor is a pressure transducer inserted into the measuring cylinder.

8. The injection unit is, A plasticizing unit having a plasticizing cylinder to which the molding material is supplied, and a plasticizing screw rotatably provided within the plasticizing cylinder, An injection unit having an injection cylinder in which the molding material sent from the plasticizing cylinder is stored, and a plunger which is the injection shaft provided within the injection cylinder so as to be able to move back and forth, The injection molding machine according to claim 1, further comprising a junction connecting the plasticizing cylinder and the injection cylinder.

9. A method for measuring fluidity using an injection molding machine as described in claim 1, Preparation process, A step of weighing the molding material, A step of advancing the injection shaft to the measurement start position and cutting the molding material discharged from the die hole, A step of advancing the injection shaft for a predetermined time and cutting the molded material discharged from the die hole to obtain a sample, A step of weighing the mass of the sample, A step of inputting the mass of the sample into the control device, A fluidity measurement method comprising the step of the control device calculating the melt mass flow rate.

10. A method for measuring fluidity using an injection molding machine as described in claim 1, Preparation process, A step of weighing the molding material, A step of advancing the injection shaft to the measurement start position, A step of measuring the distance the injection shaft moves in a predetermined time or the time required for the injection shaft to move a predetermined distance, A fluidity measurement method comprising the step of the control device calculating the melt volume flow rate.

11. The aforementioned preparatory steps are: The process of setting test conditions, A step of heating the injection unit and the measuring cylinder to a predetermined temperature, A step of purging the molding material with the purge opening selected as the discharge destination for the molding material, A method for measuring fluidity according to claim 9 or claim 10, comprising the step of switching the discharge destination of the molding material to the die after purging.

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