Injection molding machine and flowability measurement method

Abstract

An injection molding machine is provided that can more easily measure the melt flow rate by utilizing the mechanism of the injection molding machine. [Solution] The injection molding machine includes an injection unit, a measurement unit 5, a position sensor, a pressure sensor, and a control device. The measurement 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 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 a set test load, thereby discharging the molding material from the die hole 621, and to calculate the melt flow rate.

Description

[Technical Field]

[0001] The present invention relates to an injection molding machine and a method for measuring flowability using the 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 used, for example, to determine molding conditions and to help with quality control. Parameters that indicate the properties of molding materials include viscosity and fluidity.

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

[0004] [Patent Document 1] Patent No. 7328431 [Patent Document 2] Patent No. 7560623 Summary of the Invention [Problem to be solved by the invention]

[0005] Depending on the type of molding material, fluidity may be a more appropriate parameter to represent its characteristics than viscosity. For example, when comparing molding materials that are highly pressure-dependent, it is more appropriate to compare them based on fluidity.

[0006] The melt flow rate is known as one of the indicators of fluidity. More specifically, the melt flow rate is expressed as the melt mass flow rate (MFR) [g / 10 min] or the melt volume flow rate (MVR) [cm3 It is expressed as [m / 10 min]. Typically, 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. Furthermore, the measurement requires manual work, such as filling the cylinder with the molding material, making it 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] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an injection molding machine and a flowability measurement method that can more easily measure the melt flow rate by utilizing the mechanism of the injection molding machine. [Means for solving the problem]

[0008] According to the present invention, there is provided an injection molding machine comprising: an injection unit that extrudes and injects a molding material with an injection shaft; a measurement unit attached to the injection unit; a position sensor that measures the position of the injection shaft; a pressure sensor that measures the pressure of the molding material; and a control device, wherein the measurement unit includes: a measuring cylinder that is attached to the injection unit and through which the molding material injected by the injection unit flows; a die that is attached to the measuring cylinder and has a die hole configured to allow the molding material to flow; a purge opening that is provided in the measuring cylinder and has a cross-sectional area larger than that of the die hole and configured to allow the molding material to flow; and a flow path switching pin that selectively switches the destination of the molding material to either the die or the purge opening; and the control device is configured to measure 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 a melt flow rate based on one of the mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined time intervals, the distance traveled by the injection shaft in a predetermined time, and the time required for the injection shaft to travel the predetermined distance. [Effects of the Invention]

[0009] The injection molding machine according to the present invention allows the melt flow rate to be measured by utilizing the mechanism of the injection molding machine. In particular, the advance preparation and measurement can be easily performed, thereby reducing the burden on the operator who measures the melt flow rate. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating the configuration of an injection molding machine according to an embodiment of the present invention, with an injection nozzle attached thereto; [Figure 2] 1 is a schematic configuration diagram of an injection molding machine according to an embodiment of the present invention, with a measurement unit attached thereto; [Figure 3] FIG. 2 is a perspective view of the measurement unit as seen from above. [Figure 4] FIG. 2 is a perspective view of the measurement unit as seen from below. [Figure 5] FIG. 2 is a side cross-sectional view of the measurement unit. [Figure 6] FIG. 6 is a front cross-sectional view of the measurement unit taken along the line VI-VI. [Figure 7] FIG. 2 is a cross-sectional view of a die. [Figure 8] FIG. 2 is a block diagram of a control device. [Figure 9] 1 is an example of a GUI for measuring the melt mass flow rate. [Figure 10] This is an example of a GUI for measuring the melt volume flow rate. [Figure 11] 1 is an example of a flowchart for measuring a melt mass flow rate. [Figure 12] 1 is an example of a flowchart for measuring a melt volume flow rate. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] The injection molding machine of this embodiment includes an injection unit 1 that extrudes and injects molding material using an injection shaft; a clamping unit (not shown) that opens, closes, and clamps a mold (not shown); and a control device 7 that controls the injection unit 1 and the clamping unit. During injection molding, the injection unit 1 plasticizes the molding material, measures out a predetermined amount, and then injects it through an injection nozzle 46. The clamping unit is configured to hold the mold and open, close, and clamp the mold. When the molding material is injected during injection molding, the clamping unit closes the mold and applies a predetermined clamping force to the mold. After the molding material injected from the injection nozzle 46 into the mold cavity is cooled and forms a molded product, the clamping unit opens the mold, ejects the molded product, and then closes the mold again. Well-known configurations, such as a direct pressure type or toggle type, can be used as the clamping unit.

[0013] In this specification, the term "molding material" refers broadly to any material that can be injected by an injection molding machine, and includes not only materials primarily made of resin, but also 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. While the following description uses an injection molding machine that uses a thermoplastic molding material as an example, the present invention is also applicable to injection molding machines that use a thermosetting molding material. Thermosetting molding materials include LIM materials, which are thermosetting liquid materials.

[0014] The injection molding machine of this embodiment is a so-called screw pre-plasticizing injection molding machine in which the plasticizing section 2 and the injection section 4 are configured separately. As shown in FIG. 1, the injection unit 1 includes the plasticizing section 2, a junction 3, and the injection section 4. In FIG. 1, a partial configuration is shown in cross section. In the following, the left side in FIG. 1, i.e., the side from which the molding material is injected, is referred to as the front side. The right side in FIG. 1, i.e., the side from which the molding material is supplied, is referred to as the rear side.

[0015] The plasticizing section 2 includes a plasticizing cylinder 21, a plasticizing screw 23, a check device 25, a plasticizing screw driver 27, and a heater 29. The plasticizing cylinder 21 is a hollow cylinder 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 within the plasticizing cylinder 21. The plasticizing screw 23 melts the molding material supplied from the material inlet 211 into the plasticizing cylinder 21 by the heat from the heater 29 and shear heat, and sends it forward. The check device 25 is an actuator, such as a fluid pressure cylinder or an electric cylinder, that advances the plasticizing screw 23. Upon completion of metering, the check device 25 advances the plasticizing screw 23 to block the flow path, preventing 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] The junction 3 connects the plasticizing cylinder 21 of the plasticizing section 2 and the injection cylinder 41 of the injection section 4. The junction 3 may be heated to a predetermined temperature by a heater.

[0017] The injection unit 4 includes an injection cylinder 41, a plunger 42 serving as an injection axis, a plunger driving 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 cylinder that is heated to a predetermined temperature by a heater 47 such as a band heater. The injection cylinder 41 stores the molding material sent from the plasticizing cylinder 21. The plunger 42 is a generally cylindrical member that is freely movable back and forth within the injection cylinder 41. In a screw pre-plasticizing injection molding machine, the plunger 42 corresponds to the injection shaft that pushes out and injects the molding material. The plunger drive unit 43 is any actuator that moves the plunger 42 back and forth, such as a hydraulic cylinder or an electric cylinder. The plunger 42 and the piston rod of the plunger drive unit 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 directly or indirectly measure the position of the plunger 42, such as a linear scale. When the plunger driving 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 that can directly or indirectly measure the pressure applied to the plunger 42, such as a load cell provided between the plunger 42 and the piston rod. When the plunger driver 43 is a hydraulic cylinder, the pressure sensor 442 may be a hydraulic gauge. When the plunger driver 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 attached to the 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 flow path connecting the junction 3 and the injection cylinder 41, and a discharge flow path connecting the injection cylinder 41 and the injection nozzle 46. A nozzle mounting hole 451 to which the injection nozzle 46 can be attached is formed on the front surface of the nozzle cylinder 45. More specifically, a female thread is formed on the inner wall of the nozzle mounting hole 451 to be threaded 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 in the plasticizing section 2 is sent to the injection cylinder 41 via the junction 3 and the nozzle cylinder 45. In the injection cylinder 41, the molding material is stored in front of the plunger 42, and the desired amount of molding material is measured out. After measuring, the check device 25 prevents backflow into the plasticizing section 2, and then the plunger 42 is moved forward, whereupon the molding material is sent 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 measuring unit 5 of this embodiment will be described. The measuring unit 5 is attached to the injection unit 1 when measuring the melt flow rate of the molding material. The measuring unit 5 may be attached in any position forward 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 FIG. 2. That is, the injection nozzle 46 is removed from the nozzle cylinder 45, and the measuring cylinder 50 of the measuring unit 5 is attached to the nozzle attachment hole 451 of the nozzle cylinder 45. A detailed method of attaching the measuring 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 fixed plate 65, a positioning rod 66, and heaters 67 and 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 of this embodiment includes a first cylinder 51 and a second cylinder 52, which are configured to be separable from each other. The first cylinder 51 and the second cylinder 52 are fastened together by a cover nut 53, which serves as 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, an attachment portion 512, and a flange 513. The flow path 511 is formed so as to penetrate the interior of the first cylinder 51 in the axial direction, and is connected to the discharge flow path of the nozzle cylinder 45. The attachment portion 512 is provided at the rear end of the first cylinder 51, and is formed with a male thread that screws into a female thread formed in the nozzle attachment 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, the rear end of the second cylinder 52 is formed with a male thread that screws into a female thread formed in the inner hole of the cover nut 53.

[0028] The flow path 521 is formed in the axial direction inside the second cylinder 52, and is connected to the flow path 511 and a flow path switching pin mounting hole 522. The flow path switching pin mounting hole 522 is a hole formed in 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 in the radial direction 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 attachment hole 524 is a hole formed in the side surface of the second cylinder 52. In this embodiment, two die attachment holes 524 are provided, one to which the die 62 is fixed and the other to which the purge opening 63 functions. That is, in this embodiment, the die attachment holes 524 and the purge opening 63 are mutually interchangeable components, but it is not essential that the die 62 be attachable to the purge opening 63. In other words, it is sufficient that at least one of the holes communicating with the flow path 523 is capable of attaching the die 62. In this embodiment, a female thread is formed on the inner wall of the die attachment hole 524, and a male thread is formed on the outer periphery of the die 62, and these threads are screwed together to enable easy attachment and detachment.

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

[0031] The pressure sensor 61 is a pressure transducer that is 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 inside the flow path 521 of the second cylinder 52.

[0032] As described below, when measuring the melt flow rate, the plunger 42 is advanced with a set test load when the molding material is discharged from the die 62. At this time, i.e., during measurement, feedback control is performed based on the measured molding material pressure so that the molding material pressure matches the test load. The test load, i.e., the molding material pressure during melt flow rate measurement, is significantly lower than the molding material pressure generated during normal injection molding. Therefore, the pressure sensor 442 of the injection section 4, which is intended for use in detecting pressure during injection molding, may not be able to accurately detect the pressure during melt flow rate measurement. Therefore, by providing a pressure sensor 61 suitable for measuring low pressures in the measuring cylinder 50 and referring to the detected value of the pressure sensor 61 during melt flow rate measurement, more accurate feedback accuracy of the plunger 42 can be achieved, thereby improving the accuracy of the melt flow rate measurement. The measurable range of the pressure sensor 61 is preferably a low pressure range, e.g., above 0 MPa and below approximately 20 MPa. However, if acceptable measurement accuracy can be obtained even when pressure sensor 442 is used, pressure sensor 61 may be omitted and pressure sensor 442 may be used for feedback control when measuring the melt flow rate.

[0033] As shown in FIG. 7 , a die 62 having a die hole 621 configured to allow the molding material to flow through 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), a standard die or half-size die specified in the relevant standards is used as the die 62. The standard die is a die 62 having a die hole 621 with an effective length L of 8.000 mm and a hole diameter φ of 2.095 mm. The half-size die is a die 62 having a die hole 621 with an effective length L of 4.000 mm and a hole diameter φ of 1.050 mm. The die hole 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 paths in the die 62 other than the die holes 621 need only have a cross-sectional area large enough to allow the flow of the molding material without any impediments.

[0034] The purge opening 63 is a hole provided in the measuring cylinder 50 and is configured to allow the molding material to flow through it. The purge opening 63 has a cross-sectional area large enough to allow the molding material to flow freely. The cross-sectional area of ​​the purge opening 63 is at least larger than the cross-sectional area of ​​the die hole 621. The diameter of the purge opening 63 is, for example, approximately 4.0 mm or more and approximately 6.0 mm or less. Before measuring the melt flow rate, a preliminary step called purging is performed, in which the existing molding material in the injection unit 1 is replaced with the molding material to be measured and the molding material is discharged until the condition stabilizes. Because the die hole 621 of the die 62 has a very small diameter, attempting to discharge the molding material through the die hole 621 during purging takes a long time and places a heavy load on the device. Therefore, discharging the molding material through the purge opening 63 during purging allows for efficient purging.

[0035] 6, the empty die attachment hole 524 is used as the purge opening 63. However, a cylinder having a sufficiently large through-hole may be attached to the die attachment hole 524, and the through-hole may be used as the purge opening 63. The cylinder may be configured to be able to be screwed into the die attachment hole 524. Using the cylinder can prevent the molding material discharged during purging from adhering to the inner wall of the die attachment 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. The flow path switching pin 64 of this embodiment is a cylindrical member rotatably inserted 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 90° in the middle, and its inlet side is connected to the flow path 521 and its outlet side is 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 can be fitted with a tool of any shape. In this embodiment, the tool hole 642 is a hexagonal hole that can be fitted with a hexagonal wrench. The flow path switching pin 64 can be rotated by fitting a tool into the tool hole 642. The recess 643 is a hole formed in the side surface of the flow path switching pin 64, and is provided at a position where it will connect with one of the positioning rod insertion holes 526 when the flow path 641 is connected to one of the flow paths 523. That is, in this embodiment, the flow path switching pin 64 is provided 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 fixed plate 65 is a plate-like member fixed to the front surface of the second cylinder 52 with bolts or the like, and abuts against the flow path switching pin 64 to prevent the flow path switching pin 64 from falling off. An opening is formed in the center of the fixed 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. After the flow path switching pin 64 is rotated to select the flow path to be used, the positioning rod 66 is inserted into the positioning rod insertion hole 526. As a result, the tip of the positioning rod 66 fits into the recess 643, and the flow path switching pin 64 is accurately positioned and prevented from unexpected rotation.

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

[0040] To prevent the molding material discharged from the die 62 and the purge opening 63 from scattering, it is preferable to attach the measuring cylinder 50 to the injection unit 1 so that the die 62 and the purge opening 63 face downward. Specifically, the measuring cylinder 50 is attached in the following manner. First, the cover nut 53 is inserted into the first cylinder 51, and the mounting portion 512 of the first cylinder 51 is threaded into the nozzle mounting hole of the nozzle cylinder 45. Next, the first cylinder 51 and the second cylinder 52 are engaged with each other, and the second cylinder 52 is positioned so that the die mounting hole 524 faces downward. In this state, the cover nut 53 is threaded onto the second cylinder 52 and rotated until the wall surface 531 of the cover nut 53 abuts against the flange 513 of the first cylinder 51. In this manner, the first cylinder 51 and the second cylinder 52 are fastened together.

[0041] The members 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 using the cover nut 53, but other fastening means such as bolts may also be used.

[0042] After fastening the first cylinder 51 and the second cylinder 52 together using the above procedure, the first cylinder 51 is aligned so that the die 62 and the purge opening 63 face downward when the first cylinder 51 is screwed into the nozzle mounting hole 451. Therefore, if the first cylinder 51 and the second cylinder 52 are fastened using the above procedure, they may be attached to the nozzle cylinder 45 in an assembled state. However, if the injection molding machine to which they are attached is changed, the alignment must be performed again using the same procedure.

[0043] In order to orient the die 62 and purge opening 63 downward, it is desirable that the angle formed by the line passing through the center of the die 62 and the line passing through the center of the purge opening 63 is 40° or less in a front view.

[0044] The control device 7 of this embodiment will now be described. The control device 7 controls the injection unit 1 and the mold clamping unit, and is configured to calculate the melt flow rate based on any one of the mass of a sample obtained by cutting the molding material discharged from the die hole 621 at predetermined intervals, the distance traveled by the plunger 42 at predetermined intervals, and the time required for the plunger 42 to travel the predetermined distance. The melt mass flow rate can be calculated directly based on the mass of a sample obtained by cutting the molding material discharged from the die hole 621 at predetermined intervals. The melt volume flow rate can be calculated directly based on the distance traveled by the plunger 42 at predetermined intervals or the time required for the plunger 42 to travel the predetermined distance. Furthermore, the melt mass flow rate and the melt volume flow rate can be converted to each other based on the density of the molding material.

[0045] The control device 7 may be configured using any combination of hardware and software. For example, as shown in FIG. 8 , it includes a calculation device 71, a storage device 72, an input device 73, a display device 74, a timer 75, and a sound output device 76. The calculation device 71 is an arbitrary calculation circuit such as a CPU, and performs various calculations to control each component, as well as calculations related to melt flow rate calculation. The storage device 72 may be configured using any combination of RAM, ROM, and auxiliary storage devices, and stores data necessary for the calculations performed by the calculation device 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 may include a device that serves both purposes, such as a touch panel. In this embodiment, a control 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 notify an operator of the timing to cut the molding material discharged from the die hole 621. In this embodiment, the notification means is composed of a display device 74 and a sound output device 76. That is, the display device 74 displays a message or an image to notify the operator of the timing to cut the molding material. Furthermore, the sound output device 76 outputs a buzzer sound or voice to notify the operator of the timing to cut the molding material. The notification means is not limited to these devices and may be composed of other devices such as a lamp, or one or more devices may be used in any combination.

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

[0048] The control device 7 controls the 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 temperatures. However, the heaters 67 and 68 are not used during injection molding. Furthermore, the heater 48 is not used during melt flow rate measurement. Temperature sensors such as thermocouples may be provided in each section, and the heaters 29, 47, 48, 67, and 68 may be feedback-controlled based on the measured temperatures.

[0049] 9 and 10 show an example of a GUI for measuring the melt flow rate, which is displayed on the display device 74. The GUI for measuring the melt flow rate can be accessed from the GUI for normal injection molding. The injection molding machine of this embodiment is configured to be able to switch 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] 9, the GUI for the MFR mode includes, for example, a test condition input section 80, a measurement start button 81, a message display section 82, a measurement result input section 83, a calculation start button 84, a calculation result display section 86, a data save button 87, a data display section 88, and an end button 89. As shown in FIG. 10, the GUI for the MVR mode includes, for example, a test condition input section 80, a measurement start button 81, a calculation start button 84, a measurement result display section 85, a calculation result display section 86, a data save button 87, a data display section 88, and an end button 89.

[0051] The test condition input section 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 selectable 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 input into the input field for the test conditions. The automatically input test conditions may be changed as necessary. The operator can also manually input the test conditions.

[0052] The test conditions for MFR mode are: Test load [kgf]: Set pressure to advance plunger 42 Test temperature [℃]: Set temperature of injection unit 1 and measurement cylinder 50 Sample cutting time [sec]: time interval for cutting the molding material discharged from the die hole 621 Number of measurements: Number of times the molding material is cut to obtain a sample It has.

[0053] When measuring the distance that the plunger 42 moves in a predetermined time, the test conditions in the MVR mode are as follows: Test load [kgf]: Set pressure to advance plunger 42 Test temperature [℃]: Set temperature of injection unit 1 and measurement cylinder 50 Movement time [sec]: Time required to advance the plunger 42 Number of measurements: the number of times the movement distance of the plunger 42 is measured It has.

[0054] When measuring the time required for the plunger 42 to move a predetermined distance, the test conditions in the MVR mode are as follows: Test load [kgf]: Set pressure to advance plunger 42 Test temperature [℃]: Set temperature of injection unit 1 and measurement cylinder 50 Movement distance [mm]: distance to advance plunger 42 Number of measurements: the number of times the movement time of the plunger 42 is measured It has.

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

[0056] When the measurement start button 81 is pressed, the control device 7 receives an 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 ejects the molding material from the die hole 621 of the die 62.

[0057] In this embodiment, when measuring the melt mass flow rate in the MFR mode, the operator manually cuts the sample. The timing to cut 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 that cuts the molding material discharged from the die hole 621 may be provided so that the sample is automatically cut. 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 meter and manually inputs the mass into the measurement result input unit 83. After that, 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 meter connected to the control device 7 may be provided so that the mass of the sample is automatically input.

[0059] In the MVR mode of this embodiment, the distance traveled by the plunger 42 in a predetermined time is displayed on the measurement result display unit 85, and the value of 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 a predetermined distance may be displayed on the measurement result display unit 85, and the value of the melt volume flow rate calculated based on that time may be displayed on the calculation result display unit 86. In this embodiment, the value of 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 may be saved in an external storage medium 77 such as a portable storage medium such as a flash memory. Measurement data once saved in the storage device 72 of the control device 7 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 measurement data displayed on the data display unit 88 may be able to be displayed or hidden as desired. The device may be configured to allow supplemental information to be added to the measurement data.

[0061] When the end button 89 is pressed, the GUI for measuring the melt flow rate is closed and the GUI for normal injection molding is displayed.

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

[0063] FIG. 11 is an example of a flowchart for calculating the melt mass flow rate using the MFR mode.

[0064] First, advance preparation for measurement is performed (S11). This advance preparation may include the following steps. As described above, the operator sets the test conditions required for measurement. The plasticizing section 2, the injection unit 1 including the injection section 4, and the measuring cylinder 50 are heated to a predetermined temperature, i.e., the test temperature. After the temperature rise of each section is complete, the molding material to be measured is introduced into the material inlet 211 to purge the molding material. During purging, the flow path switching pin 64 sets the molding material discharge destination to the purge opening 63, and the molding material sent from the plasticizing section 2 and the injection section 4 passes through the measuring cylinder 50 and is discharged from the purge opening 63. Purging can be performed in two ways: a rolling purge, which is performed with the plunger 42 fixed, and a metering purge, which involves metering using the injection cylinder 41 and injection using the plunger 42. Either one of these methods may be performed, or a combination of these methods may be performed. After the purging is completed, 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 in order to achieve high-precision measurements. 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, which eliminates the need for large-scale work and allows for quick progress to measurement.

[0066] When the measurement start button 81 is pressed to start measurement, the molding material is metered (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 as it pushes down. When the plunger 42 reaches a predetermined position, metering is considered complete, the plasticizing screw 23 stops, and backflow prevention is performed by the non-return device 25. The measured amount need only be sufficient for measurement; for example, the maximum amount that can be measured in the injection section 4 may be measured. Note that with an extrusion-type plastometer, after filling the cylinder with molding material, a process of compressing the material with a rod to degas the material is required. However, when metering using an injection molding machine as in this embodiment, this process is not necessary in principle because metering can be performed with almost no air entrapment.

[0067] Next, the plunger 42 starts 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, the molten molding material is ejected 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 begins when the plunger 42 reaches the predetermined measurement start position.

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

[0069] The plunger 42 continues to advance, and each time the time set as the sample cutting time elapses, the notifying means notifies 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 the sample. That is, the process of advancing the plunger 42 for a predetermined time and cutting the molding material to obtain the sample is repeated the set number of times (S15-S17).

[0070] When cutting the molding material, the movement of plunger 42 may be temporarily stopped. That is, control device 7 may temporarily stop the movement of plunger 42 at the start of the test and when a sample is taken. Plunger 42 may resume forward movement after a predetermined time has elapsed, or may resume forward movement based on an instruction 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]: Melt mass flow rate m n [g]: mass of the sample at the nth measurement t[sec]: Sample cutting time n [times]: number of measurements Let's say.

[0072]

number

[0073] FIG. 12 is an example of a flowchart for calculating the melt volume flow rate using the MVR mode.

[0074] The same procedures as for calculating the melt mass-flow rate are performed: advance preparation (S31), weighing of the molding material (S32), and advancement of the plunger 42 to the weighing start position (S33). The subsequent flow branches depending on whether the measurement target is the distance traveled by the plunger 42 in a specified time or the time required for the plunger 42 to travel the specified distance (S34).

[0075] The flow for measuring the distance traveled by the plunger 42 is as follows. Every time a time set as the travel time elapses, the position of the plunger 42 at that time is read and the travel distance is calculated. That is, the measurement of the distance traveled by the plunger 42 in a predetermined time is repeated the set number of times (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 / 10min]: Melt volume flow rate A [cm 2 ]: cross-sectional area of ​​plunger 42 l n [cm]: nth time movement distance of plunger 42 t [sec]: movement time of plunger 42 n [times]: number of measurements Let's say.

[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 movement distance, the time required for the movement is calculated. That is, the measurement of the time required for the plunger 42 to move a predetermined distance is repeated the set number of times (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 / 10min]: Melt volume flow rate A [cm 2 ]: cross-sectional area of ​​plunger 42 l [cm]: travel distance of plunger 42 t n [sec]: nth movement time of plunger 42 n [times]: number of measurements Let's say.

[0078]

number

[0079] The melt volume flow rate may be converted into a 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, where: MFR [g / 10min]: Melt mass flow rate MVR [cm 3 / 10min]: Melt volume flow rate ρ [g / cm 3 ]: Density of molding material at test temperature Conversely, the melt mass flow rate may be converted into a melt volume flow rate and displayed on the calculation result display unit 86.

[0080]

number

[0081] If the density is known, that information can be referenced, but it may also be calculated based on the mass of a 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, where: ρ [g / cm 3 ]: Density of molding material at test temperature m n [g]: mass of the sample at the nth measurement A [cm2 ]: cross-sectional area of ​​plunger 42 l [cm]: travel distance of plunger 42 n [times]: number of measurements Let's say.

[0082]

number

[0083] The density may be calculated on the injection molding machine using the same device as used to measure the melt flow rate. In this case, the injection molding machine may be configured to be able to display a GUI related to a density measurement mode for measuring the density on the display device 74. The operator may enter the following as test conditions for the density measurement mode: Test load [kgf]: Set pressure to advance plunger 42 Test temperature [℃]: Set temperature of injection unit 1 and measurement cylinder 50 Movement distance [mm]: distance to advance plunger 42 Number of measurements: Number of times the molding material is cut to obtain a sample When measuring density, theoretically, it is required to measure at the same test temperature and test pressure as when measuring the melt flow rate later. However, the test pressure is low enough that it does not have to be the same. Weigh the molding material and move the plunger 4 to the measurement start position. 2 After the movement, the molding material is cut to obtain a sample every time the moving distance is set based on the same procedure as in the measurement in MFR mode. Based on the mass of the measured sample, the control device 7 calculates and displays the density using the above formula.

[0084] The injection molding machine of this embodiment allows for 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 using an extrusion plastometer. Furthermore, compared to an extrusion plastometer, it has the advantage of placing less of a burden on the operator, particularly in terms of requiring less preparation work. Furthermore, it is possible to perform viscosity measurements equivalent to those performed by an extrusion plastometer, under an environment closer to that of actual injection molding.

[0085] The injection molding machine for carrying out the fluidity measurement method of this embodiment may be a so-called inline screw injection molding machine in which the plasticizing section 2 and the injection section 4 are integrated. An inline screw injection molding machine includes a cylinder and a screw that is rotatable and retractable within the cylinder, serving as both the plasticizing section 2 and the injection section 4. In an inline screw injection molding machine, the screw corresponds to the injection axis. However, a screw pre-plasticizing injection molding machine equipped with a check device 25 that advances the plasticizing screw 23 to prevent backflow, like the injection molding machine of this embodiment, offers superior metering and injection stability and reproducibility compared to an inline screw 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 within the scope that does not deviate from the technical concept of the present invention. [Explanation of symbols]

[0087] 1 injection unit 2. Plasticization Section 3 Junction 4 Injection part 42 Plunger 441 Position Sensor 5 Measuring Unit 50 Measuring Cylinder 61 Pressure Sensor 62 Die 621 Die hole 63 Purge opening 64 Flow path switching pin 7 Control Device 74 Display device 76 Sound output device

Claims

1. an injection unit that extrudes and injects molding material using an injection shaft; a measurement unit attached to the injection unit; a position sensor for measuring the position of the injection axis; a pressure sensor for measuring the pressure of the molding material; a control device; The measuring unit a measuring cylinder attached to the injection unit and 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; a purge opening provided in the measuring cylinder, the purge opening having a cross-sectional area larger than that of the die hole, and configured to allow the molding material to flow therethrough; a flow path switching pin that selectively switches the discharge destination of the molding material to either the die or the purge opening, the control device is configured to, when instructed to start measurement, weigh the molding material, 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 a melt flow rate based on any one of the mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined time intervals, the distance traveled by the injection shaft in a predetermined time, and the time required for the injection shaft to travel the predetermined distance.

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

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

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

5. a cutting device that cuts the molding material discharged from the die hole; 2. The injection molding machine according to claim 1, wherein the control device is configured to calculate a melt mass flow rate based on a mass of a sample obtained by cutting the molding material discharged from the die hole at predetermined time intervals.

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

7. 2. 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 comprises: a plasticizing section including a plasticizing cylinder to which the molding material is supplied and a plasticizing screw rotatably provided within the plasticizing cylinder; an injection section including an injection cylinder in which the molding material sent from the plasticizing cylinder is stored, and a plunger serving as the injection shaft provided in the injection cylinder so as to be able to move forward and backward; 2. The injection molding machine according to claim 1, further comprising: a junction connecting the plasticizing cylinder and the injection cylinder.

9. A flowability measurement method using the injection molding machine according to claim 1, The advance preparation process and A step of measuring the molding material; a step of advancing the injection shaft to a 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 molding material discharged from the die hole to obtain a sample; Weighing the mass of the sample; inputting the mass of the sample into the controller; The control device calculates a melt mass flow rate.

10. A flowability measurement method using the injection molding machine according to claim 1, The advance preparation process and A step of measuring the molding material; advancing the injection shaft to a measurement start position; measuring a distance traveled by the injection shaft in a predetermined time or a time required for the injection shaft to travel a predetermined distance; The control device calculates a melt volume flow rate.

11. The advance preparation step includes: Setting test conditions; heating the injection unit and the measuring cylinder to a predetermined temperature; purging the molding material with the purge opening selected as the discharge destination of the molding material; The flowability measuring method according to claim 9 or 10, further comprising: a step of switching a discharge destination of the molding material to the die after purging.

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