Forming device

Abstract

To provide a technique for achieving both accuracy and stability in a supply amount of a liquid additive to be added to a resin material in a molding apparatus.SOLUTION: An injection molding apparatus 1 includes: a liquid supply device 50 for supplying a liquid additive 98 to a resin pellet 99; a control panel 80 (liquid supply controller) for controlling a supply of the liquid additive 98 by the liquid supply device 50; a droplet supply port 17 for ejecting the liquid additive 98 into a hopper 13 or a path between the hopper 13 and a cylinder 11; a receiving container 54 for storing the liquid additive 98 to be supplied to the liquid supply device 50; and a load cell 57 for weighing the liquid additive 98 stored in the receiving container 54. The control panel 80 includes: a synchronization control unit that synchronizes a timing of supplying the resin pellets 99 to the cylinder 11 and a timing of supplying the liquid additive 98 from the liquid supply device 50; and a supply control unit that controls an amount of the liquid additive 98 supplied by the liquid supply device 50 based on a measurement result of the liquid additive 98 by the load cell 57.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a molding apparatus for injecting a resin material into a mold by an extruder for molding.

Background Art

[0002] In molding apparatuses for performing injection molding or blow molding, as an example, a technique of mixing a resin material (resin pellets or resin powder) and a liquid additive (high-concentration pigment dispersion or plastic additive dispersion) during molding for each shot is known. For example, a technique has been proposed in which a raw material resin and microencapsulated liquid color as a colorant are supplied to a material supply hopper of an injection molding machine at a certain ratio to produce a colored molded product (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Accuracy in metering when adding a liquid additive to a resin material is required. For example, when the liquid additive is a colorant, a slight variation in the supply amount may cause a color difference in the product. Further, even if an appropriate initial supply amount is set, it may gradually change, and it has been required to improve the stability of the supply amount of the liquid additive. In the technique disclosed in Patent Document 1, there is no disclosure of a technique from the viewpoint of improving the stability of the supply amount of the liquid additive, and a new technique has been required.

[0005] The present invention has been made in view of such a situation, and an object thereof is to provide a technique for achieving both accuracy and stability of the supply amount of a liquid additive added to a resin material in a molding apparatus for molding a resin material with an extruder.

Means for Solving the Problems

[0006] According to the present invention, in a molding apparatus including at least an extruder having a cylinder in which a screw is provided so as to be drivable in a rotational direction and an axial direction, and a hopper for supplying a resin material to the cylinder, a droplet supply device for supplying a liquid additive to be mixed with the resin material to the resin material, a control unit for controlling the supply of the liquid additive to the resin material by the droplet supply device, a supply port through which the liquid additive discharges in a path between the hopper or between the hopper and the cylinder, a container for storing the liquid additive to be supplied to the droplet supply device, a measuring unit for measuring the liquid additive stored in the container, the control unit has a synchronization control function for synchronizing the timing of supplying the resin material to the cylinder and the timing of the droplet supply device supplying the liquid additive, and a supply control function for controlling the supply amount of the liquid additive by the droplet supply device based on the measurement result of the liquid additive by the measuring unit. A molding apparatus having these is provided.

Advantages of the Invention

[0007] According to the present invention, in a molding apparatus for molding a resin material with an extruder, it is possible to provide a technique for achieving both accuracy and stability of the supply amount of a liquid additive added to the resin material.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0009] Embodiments of the present invention will be described with reference to the drawings. <Overview of Injection Molding Apparatus 1> FIG. 1 is a schematic diagram showing a schematic configuration of an injection molding apparatus 1, shown as a sectional view so that the internal structure can be understood. In the present embodiment, an injection molding apparatus 1 that performs so-called injection blow molding is exemplified, but the present invention is not limited to this, and it can be applied to general injection molding, extrusion molding, compression molding, press molding, and other apparatuses that perform molding by injection with an extruder. First, an overview of the injection unit 10 and the injection molding process will be described.

[0010] The injection molding apparatus 1 includes an injection unit 10, a mold clamping unit 30, a liquid supply device 50, and a control panel 80 that controls them. In the injection unit 10, the resin pellets 99 and the liquid additive 98 supplied to the hopper 13 are kneaded in the cylinder 11 and injected from the injection nozzle 12 into the mold clamping unit 30.

[0011] Resin pellets 99 are the molding raw materials of thermoplastic plastics (resins), which are formed by melting and kneading resin materials and various composite materials (additives), and generally have a small spherical or cylindrical shape.

[0012] The liquid additive 98 is a coloring agent such as liquid color, and in addition, it may be various liquid additives added to the resin pellets 99, or a liquid additive in which solid additives are dispersed.

[0013] The liquid additive 98 is filled in the filling container 60 and supplied to the liquid supply device 50. Here, the liquid additive 98 is temporarily stored at one end in the receiving container 54 from the filling container 60. Further, the tube pump 53 of the liquid supply device 50 sucks the liquid additive 98 stored in the receiving container 54 and supplies it to the resin pellets 99 in the hopper 13. It is preferable to use a deformable pouch container or a container having an opening that functions as a pouring port and a ventilation hole for the filling container 60 so that the liquid additive 98 can be dropped by gravity into the receiving container 54. In this embodiment, a pouch container is exemplified as the filling container 60.

[0014] In the mold clamping unit 30, the resin material (the material in which the resin pellets 99 and the liquid additive 98 are kneaded) injected from the injection unit 10 is filled into the preform mold 31, and an intermediate molded product called a preform 71 is molded (injection process).

[0015] Subsequently, the preform 71 is attached to the pot mold 32, and partial heating of the preform 71 is performed in preparation for the next blowing process (temperature control process). For example, if the finished product is a bottle, the temperature of the mouth part is controlled at a low temperature so as not to be stretched, the other stretched parts are controlled at a high temperature, and partial heating is performed at an even higher temperature for the parts where the wall thickness is to be made thinner. Finally, the preform 71 after temperature control is attached to the blow mold 33, and air 95 is blown into the inside of the preform 71 to stick it to the inner surface of the blow mold 33, thereby molding a molded product 73 of a desired shape, and the molded product 73 is taken out from the blow mold 33 as a finished product (blowing process).

[0016] <Injection unit 10> FIG. 2 is a diagram showing a schematic configuration of the injection unit 10, and is shown as a cross-sectional view. The injection unit 10 includes a cylinder 11, an injection nozzle 12, a hopper 13, a supply pipe 14, a heater 15, and a drive unit 20.

[0017] Inside the cylinder 11, a screw 19 is arranged along the axial direction so as to be drivable in the rotational direction and the axial direction. The screw 19 is driven in the rotational direction and the axial direction by the drive unit 20. The drive unit 20 is operationally controlled by the control panel 80.

[0018] A heater 15 is provided around the screw 19. Although not shown in the figure, the heater 15 is also appropriately provided in the injection nozzle 12 and the path from the injection nozzle 12 to the preform mold 31.

[0019] The hopper 13 has a so-called funnel shape having an inverted conical hopper body 13a and a cylindrical tube portion 13b provided below it, and resin pellets 99 are introduced from the upper opening portion. The shape of the cone (inverted cone) is not particularly limited, but generally can be a cone or a quadrangular pyramid. The tube portion 13b of the hopper 13 communicates with the supply pipe 14.

[0020] FIG. 3 is a schematic diagram of an adapter 16 attached to the supply pipe 14, shown as a perspective view. The supply pipe 14 connects the hopper 13 and the cylinder 11 and supplies the resin pellets 99 introduced into the hopper 13 to the cylinder 11. As the shape of the supply pipe 14, for example, it can be a cylinder with a circular cross-section. The inside of the cylinder functions as a resin supply path 14a. Generally, it has a shape considering the affinity with the connecting portion with the tube portion 13b of the hopper 13. For example, if the tube portion 13b of the hopper 13 is a cylinder, the supply pipe 14 is a cylinder, and if the tube portion 13b is a square cylinder, the supply pipe 14 is a square cylinder, but it is not limited to those shapes and can also be other polygonal shapes. Here, the cylindrical supply pipe 14 is illustrated.

[0021] In the resin supply path between the hopper 13 and the cylinder 11, a droplet supply port 17 for supplying the liquid additive 98 to the resin pellets 99 is provided. The resin supply path means that it may be provided at the boundary portion between the hopper 13 (cylindrical portion 13b) and the supply pipe 14, or may be provided in the supply pipe 14. Here, an adapter 16 provided with the droplet supply port 17 is attached to the supply pipe 14. The adapter 16 is formed of a metal plate and has a circular communication hole that communicates vertically. This communication hole functions as the resin supply path 14b. The resin supply path 14a of the supply pipe 14 and the resin supply path 14b of the adapter 16 constitute one resin supply path that extends vertically.

[0022] The droplet supply port 17 is a tubular member that communicates from the outside of the adapter 16 to the inside of the resin supply path 14b and further extends horizontally within the resin supply path 14b. One end 18b of a tube 18 extending from the liquid supply device 50 is connected to an end portion 17b of the droplet supply port 17 located outside the adapter 16.

[0023] The tip 17a of the droplet supply port 17 is arranged so as to be at the center of the circle presented by the resin supply path 14b (the inside of the cylinder of the supply pipe 14). That is, at the center of the resin supply path 14b, the liquid additive 98 is supplied to the resin pellets 99. If the resin supply path 14b is rectangular, for example, it is arranged so that the position at the intersection of the diagonals becomes the tip 17a of the droplet supply port 17. This can suppress the deviation in the mixing of the resin pellets 99 and the liquid additive 98. In addition, the adapter 16 may have a cover that covers the upper side of the droplet supply port 17 so that the droplet supply port 17 is not covered by the resin pellets 99 and the discharge performance of the liquid additive 98 does not deteriorate. As the cover, for example, a shape with an inverted V-shaped cross section can be adopted.

[0024] The droplet supply port 17 (tubular member) is composed of a metal member (such as aluminum, copper, stainless steel, etc.), a resin material, or a composite material thereof, but is not limited thereto, as long as it has a certain strength against the flow of the resin pellets 99 and has heat resistance to the heated resin pellets 99. In the case of a resin material, from the viewpoint of heat resistance, it is preferably composed of a resin material having a glass transition temperature Tg of 100°C or higher. The inner diameter of the droplet supply port 17 is appropriately set according to the required supply rate of the liquid additive 98.

[0025] <Liquid supply device 50> FIG. 4 is a perspective view showing a schematic configuration of the liquid supply device 50. The liquid supply device 50 includes a weighing device 51, a tube pump 53, a receiving container 54, a first liquid delivery pipe 55 and a second liquid delivery pipe 56 as a transport path of the liquid additive 98, and an on-off valve 59. With this configuration, the liquid supply device 50 temporarily stores the liquid additive 98 filled in the filling container 60 in the receiving container 54 and supplies it to the injection unit 10 using the tube pump 53. The filling container 60 is attached at a position above the receiving container 54, here above the weighing chamber 52, so that the liquid additive 98 can flow down by gravity.

[0026] The weighing device 51 has a weighing chamber 52 and has a load cell 57 inside. The receiving container 54 is provided on the load cell 57. The load cell 57 measures the weight of the receiving container 54 in which the liquid additive 98 is stored and notifies the measurement result to the control panel 80. Note that an elastic member (vibration damping rubber) for vibration damping may be arranged under the load cell 57.

[0027] At the upper part of the weighing chamber 52, there are a first liquid delivery pipe 55 for transporting the liquid additive 98 from the filling container 60 to the receiving container 54 and a second liquid delivery pipe 56 for transporting the liquid additive 98 from the receiving container 54 to the tube pump 53.

[0028] The upper end portion 55a of the first liquid delivery pipe 55 is attached to the filling container 60. The lower end portion 55b of the first liquid delivery pipe 55 is at a predetermined height from the bottom surface of the receiving container 54. An on-off valve 59 is provided in the first liquid delivery pipe 55, and by controlling the on-off of the flow path under the control of the control panel 80, the supply of the liquid additive 98 filled in the filling container 60 to the receiving container 54 is controlled. Here, the on-off valve 59 (that is, the flow path of the first liquid delivery pipe 55) is normally closed by a spring, and when an open signal is transmitted, the on-off valve 59 opens and the liquid additive 98 is supplied from the filling container 60 to the receiving container 54. When the transmission of the open signal stops (turns off), the on-off valve 59 closes the flow path by the spring, and the supply of the liquid additive 98 is stopped. Note that the opening and closing of the on-off valve 59 can be performed by simple control with only an open or closed signal, but it is not limited to this control method, and other controls may be used. As the on-off valve 59, in addition, a configuration combining a solenoid and a spring, an air cylinder, a pinch cock, etc. can be used.

[0029] One end portion 56b of the second liquid delivery pipe 56 is at a predetermined height from the bottom surface of the receiving container 54. The other end portion 56a of the second liquid delivery pipe 56 is attached to the flexible tube 41 of the tube pump 53 via the joint 58a. In the injection process, the tube pump 53 takes in the liquid additive 98 from the receiving container 54 via the second liquid delivery pipe 56 and supplies the set amount to the hopper 13.

[0030] There is no particular limitation on the materials of the first liquid delivery pipe 55 and the second liquid delivery pipe 56, but from the viewpoints of durability, chemical resistance, heat resistance, etc., for example, a fluororesin tube can be used.

[0031] <Tube pump 53> The tube pump 53 has a rotatable rotor, and the intermediate portion of the flexible tube 41 is wound around the outer periphery of the rotor. One end portion 41a of the flexible tube 41 is connected to the end portion 56a of the second liquid delivery pipe 56 via the joint 58a. The other end portion 41b of the flexible tube 41 is connected to one end portion 18a of the tube 18 via the joint 58b.

[0032] A plurality of rollers are attached to the outer periphery of the rotor and partially sandwich the flexible tube 41 between the inner wall of the housing and the like. As the rotor rotates, the liquid additive 98 in the receiving container 54 is sent to the hopper 13. That is, in synchronization with the drive of the injection unit 10 (for example, a signal for the drive unit 20 to drive the screw 19), the tube pump 53 is driven and the liquid additive 98 (for example, liquid color) in the receiving container 54 is sent to the hopper 13.

[0033] Note that the flexible tube 41, the above-described tube 18, the first liquid delivery pipe 55, and the second liquid delivery pipe 56 are replaced for each type of liquid additive 98 used from the viewpoint of preventing contamination of the liquid additive 98. Also, a plurality of flexible tubes 41 may be attached to the tube pump 53 in parallel. In that case, a plurality of tubes 18, first liquid delivery pipes 55, and second liquid delivery pipes 56 connected to the flexible tube 41 can be provided, or they can be joined together in the middle by a joint mechanism.

[0034] In this way, by using the tube pump 53, it is possible to achieve both the accuracy and stability of the supply amount of the liquid additive 98. Also, since the liquid additive 98 is temporarily stored in the receiving container 54 provided upstream of the tube pump 53 and the weight of the receiving container 54 is measured by the load cell 57, compared with the case of measuring downstream of the tube pump 53, the amount of the liquid additive 98 supplied to the resin pellets 99 can be accurately measured without giving fluctuations. In other words, different from a configuration in which a flow meter or the like is arranged downstream of the tube pump 53, the path from the tube pump 53 to the liquid droplet supply port 17 can be simplified, and from this viewpoint, it is also possible to achieve both the stability and accuracy of the supply amount of the liquid additive 98. Also, since the load cell 57 is arranged upstream of the tube pump 53 and is away from the injection unit 10 that is a heat source, it is not affected by temperature changes in the viscosity and density of the liquid additive 98, and stable and accurate measurement can be performed.

[0035] <Control panel 80> FIG. 5 is a functional block diagram showing a schematic configuration of the control panel 80. The control panel 80 can be configured by, for example, a processor such as an MPU (Micro Processing Unit), memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and output devices such as a voice output device and a display device connected to the processor via an input / output interface circuit. The processor executes processing using programs and various information stored in the memory. Each component of the control panel 80 may be configured as one device or may be divided into a plurality of devices.

[0036] Specifically, the control panel 80 includes a main control unit 81, an injection control unit 83, a liquid supply control unit 84, and an operation panel (not shown).

[0037] The main control unit 81 comprehensively controls each component of the control panel 80 and communicates with components of the injection molding apparatus 1 (injection unit 10, mold clamping unit 30, and liquid supply device 50) and other external devices (not shown) to perform injection molding processing in cooperation with various processes.

[0038] The injection control unit 83 controls the injection process and the blow process by the injection unit 10 and the mold clamping unit 30. The injection control unit 83 rotates and advances the screw 19 in the cylinder 11 by controlling the drive unit 20, and injects the resin pellets 99 introduced into the hopper 13 from the injection nozzle 12 into the mold clamping unit 30 (preform mold 31). At this time, the injection control unit 83 controls the heater 15 to heat and melt the resin pellets 99 in the cylinder 11.

[0039] Furthermore, as a temperature control process of the mold clamping unit 30, the injection control unit 83 partially heats the preform 71 obtained in the injection process, attaches the temperature-controlled preform 71 to the blow mold 33 as a blow molding process, and blows air 95 into the inside of the preform 71 to mold a molded product 73 having a desired shape.

[0040] The liquid supply control unit 84 includes a synchronization control unit 85, a supply control unit 86, and a dry-run prevention unit 87.

[0041] The synchronization control unit 85 controls the supply of the liquid additive 98 to the resin pellets 99 in the hopper 13 in synchronization with the injection process of the injection unit 10.

[0042] The supply control unit 86 monitors the weight variation of the liquid additive 98 in the receiving container 54 and calibrates the supply amount of the liquid additive 98 from the tube pump 53 to be the set amount. Specifically, the monitoring frequency during molding is set by operating the control panel 80. During molding, the weight variation of the receiving container 54 by the load cell 57 is monitored, compared with the set supply amount of the liquid additive 98, and the pump capacity of the tube pump 53 (i.e., the discharge amount of the liquid additive 98 per shot) is adjusted based on the error obtained by the comparison. As the monitoring frequency (number of shots), for example, it is selected from six levels of "10, 20, 30, 40, 50, 100 shots". Further, the upper limit and the lower limit of the weight of the liquid additive 98 that can fill the receiving container 54 are set. Thereby, even when the flexible tube 41 used for the tube pump 53 wears due to the discharge operation of the tube pump 53 and the supply amount of the tube pump 53 becomes different from the setting, it can be appropriately adjusted, and highly accurate supply of the liquid additive 98 is realized.

[0043] As a dry-run prevention function, the dry-run prevention unit 87 monitors that the suction port (i.e., one end 56b of the second liquid delivery pipe 56) when the liquid supply device 50 sucks the liquid additive 98 from the receiving container 54 is always inside the liquid additive 98 stored in the receiving container 54. For this purpose, the upper limit and the lower limit are set in the monitoring setting of the liquid amount of the liquid additive 98 filled in the receiving container 54. When the liquid additive 98 in the set lower limit amount is filled, the end 56b of the second liquid delivery pipe 56 is always made to be inside the liquid additive 98.

[0044] <Operation of the injection molding apparatus 1> FIG. 6 is a flowchart showing an operation example of injection molding by the injection molding apparatus 1. Here, the operation of the injection unit 10 will be described with particular attention paid to the supply operation of the liquid additive 98 by the liquid supply apparatus 50. The operation of the injection molding apparatus 1 mainly includes the initial setting S10 of the liquid supply apparatus 50 and the injection molding process S20 by the injection unit 10 and the mold clamping unit 30 based on the setting. This will be specifically described below.

[0045] <Initial setting S10 of the liquid supply apparatus 50> The initial setting S10 of the liquid supply apparatus 50 includes a tube installation process S11, a liquid agent filling process S12, a calibration process S13, and a molding preparation process S14.

[0046] [Tube installation process S11] Install a cleaned (or new) flexible tube 41 on the tube pump 53, and also install cleaned (or new) ones for the tube 18, the first liquid delivery pipe 55, and the second liquid delivery pipe 56. Note that the tube 18 is in a state of being removed from the liquid droplet supply port 17 of the adapter 16.

[0047] [Liquid agent filling process S12] Subsequently, place the receiving container 54 on the load cell 57. At this time, the lower end 55b of the first liquid delivery pipe 55 and the lower end 56a of the second liquid delivery pipe 56 are arranged inside the receiving container 54. At this time, the end 56b of the second liquid delivery pipe 56 is set to a predetermined height from the receiving container 54 from the viewpoint of preventing the liquid of the liquid additive 98 from running out during molding. At this time, the end 56b is set at a position where the flow rate of the liquid additive 98 sucked by the tube pump 53 is stable. Note that upper and lower limits are set for monitoring the liquid volume of the liquid additive 98 filled in the receiving container 54, and when the set lower limit amount is filled, the end 56b of the second liquid delivery pipe 56 is always inside the liquid additive 98. Subsequently, operate the control panel 80 to turn on the on-off valve 59 (open state) and fill the receiving container 54 with the liquid additive 98. Further, with the tube 18 removed from the droplet supply port 17 of the adapter 16, rotate the tube pump 53 to fill the tube 18 and the flexible tube 41 with the liquid additive 98.

[0048] [Calibration Step S13] For calibration, the tube pump 53 is rotated at, for example, 50% of its pump capacity rotation speed for a certain period of time, and the pump capacity value is determined from the weight reduction, rotation speed, and time inside the receiving container 54.

[0049] [Molding Preparation Step S14] After the calibration is completed, connect the tube 18 to the droplet supply port 17 of the adapter 16 and operate the control panel 80 to set various molding conditions. Specifically, first, operate the control panel 80 to input the amount of resin required for one shot of molding (the amount of resin pellets 99) and the addition rate of the liquid additive 98, and set the addition amount of the liquid additive 98 to be added to the resin pellets 99. More specifically, based on the time when the screw 19 rotates, the time considering the timing when the resin pellets 99 are introduced into the hopper 13 and the timing when the liquid additive 98 is discharged from the droplet supply port 17, the pump capacity of the tube pump 53, and the addition amount of the liquid additive 98, the pump rotation speed of the tube pump 53 is calculated. At this time, since it is necessary to obtain the pump rotation speed in advance, for the first injection molding, measure the time when the screw 19 rotates in advance and determine the pump rotation speed using that value. This step is preferably carried out by actually operating the injection molding apparatus 1 for measurement and reflecting the measurement results. However, if there is a measurement history, etc., more specifically, for example, when there is little variation in the measurement history, it may be sufficient to only set without measurement.

[0050] Subsequently, set the monitoring frequency during molding. As the monitoring frequency (number of shots), for example, select from six levels of "10, 20, 30, 40, 50, 100 shots". Further, set the upper and lower limits of the weight of the liquid additive 98 that can fill the receiving container 54. Also, the synchronization timing between the injection unit 10 and the liquid supply device 50 is set. Here, it is set at how many seconds later (or how many seconds before) the tube pump 53 is to be operated with respect to the operation timing of the injection unit 10 (extruder). Although the signal of the injection unit 10 (i.e., the supply of the resin pellets 99) is synchronized with the movement of the liquid supply device 50, at this time, it is also assumed that there may be a gap between the supply of the resin pellets 99 and the supply signal (the rotation signal of the screw 19). In order to cope with such a case, the liquid supply device 50 can set the gap in units of 0.1 seconds within, for example, 0 to 5.0 seconds.

[0051] Fig. 7 shows a timing chart of the rotation time of the screw 19, the supply time of the resin pellets 99 (denoted as "resin" in the figure) to the cylinder 11, and the pump operation time. Here, an example is shown in which the rotation time of the screw 19 is set to 10 seconds, and the synchronization timing between the supply time of the resin pellets 99 to the rotation time of the screw 19 (hereinafter referred to as the "resin supply time") and the pump operation time is set. Here, the resin supply time and the pump operation time are set to be the same. As the synchronization timing, a "delay time" from the start of rotation of the screw 19 and a "shortening time" with respect to the rotation time of the screw 19 are set.

[0052] In Fig. 7(a), an example is shown in which the "delay time" is set to "1.0 second" and the "shortening time" is set to "1.0 second". According to this setting, since there is a delay gap of 1.0 second at the start timing between the rotation signal of the screw 19 and the resin supply time, the start of operation of the tube pump 53 is set to be delayed by 1 second. Also, the stop timing of the tube pump 53 is set to be 1 second shorter than the rotation time of the screw 19.

[0053] In Fig. 7(b), an example is shown in which the "delay time" is set to "1.0 second" and the "shortening time" is set to "0 second" (no change). According to this setting, the start of operation of the tube pump 53 is set to be delayed by 1.0 second with respect to the rotation signal of the screw 19. Also, the stop timing of the tube pump 53 is set to the same timing as the rotation time of the screw 19.

[0054] In Fig. 7(c), an example is shown where the “delay time” is set to “0 seconds” (no change) and the “shortening time” is set to “1.0 second”. According to this setting, the operation start of the tube pump 53 is set to be simultaneous with the rotation signal of the screw 19. Also, the stop timing of the tube pump 53 is set to be 1.0 second shorter than the rotation time of the screw 19. In the above, an example where the resin supply time and the pump operation time match has been described, but the resin supply time and the pump operation time may be set individually.

[0055] In this way, by matching the timing of supplying the resin pellets 99 to the cylinder 11 and the timing of supplying the liquid additive 98, the liquid additive 98 spreads uniformly over the resin pellets 99, improving accuracy.

[0056] <Injection molding process S20 (operations during molding)> [Volume measurement process S21, injection process S22, temperature control process S23, blow process S24] When the molding injection process of the injection unit 10 (extruder) is started (S20), the injection unit 10 melts and kneads the resin pellets 99 and the liquid additive 98 supplied to the hopper 13 by rotating the screw 19 in the cylinder 11, and collects them at the tip portion of the cylinder 11, and measures the volume of the melt-kneaded raw material (i.e., the resin pellets 99 and the liquid additive 98) (volume measurement process S21). By pushing the screw 19 forward, the measured raw material (resin pellets 99 and liquid additive 98) is injected from the injection nozzle 12 into the preform mold 31 of the mold clamping unit 30 to obtain a preform 71 (injection process S22). The preform 71 is attached to the pot mold 32, and partial heating of the preform 71 is performed (temperature control step S23) in preparation for the next blowing process. For example, if the finished product is a bottle, the temperature of the mouth part is controlled at a low temperature so as not to be stretched, the other stretched parts are controlled at a high temperature, and partial heating is performed at an even higher temperature at the locations where the wall thickness is desired to be reduced. Finally, the preform 71 after temperature control is attached to the blow mold 33, and air 95 is blown into the interior of the preform 71 to cause it to adhere to the inner surface of the blow mold 33, thereby forming a molded product 73 of the desired shape, and the molded product 73 is taken out of the blow mold 33 as the finished product (blowing step S24).

[0057] [Liquid additive supply step S25] When the injection molding step S20 is started, in synchronization with the volume measurement step S21, the liquid supply control unit 84 of the control panel 80 executes the liquid additive supply step S25. That is, the synchronization control unit 85 of the liquid supply control unit 84 acquires the intermittent operation (signal for each shot) of the injection unit 10, and operates the tube pump 53 of the liquid supply device 50 at the pump rotation speed converted from the pump capacity and the added amount of the liquid, and supplies the liquid additive 98 to the hopper 13 through the droplet supply port 17 of the adapter 16. More specifically, the injection molding apparatus 1 is configured such that the liquid additive 98 is continuously supplied from the liquid supply device 50 during the supply of the resin pellets 99 in one injection molding, and when the supply of the resin pellets 99 for injection molding stops, the tube pump 53 also stops. Thereby, the liquid supply device 50 can stably add the liquid additive 98 to the resin pellets 99.

[0058] [Pump value correction step S26] During the supply stop of the liquid additive 98 by the liquid supply device 50, that is, during the operation stop of the tube pump 53, the liquid supply control unit 84 of the control panel 80 executes the pump value correction step S26. That is, the supply control unit 86 of the liquid supply control unit 84 acquires the measurement result of the weight of the receiving container 54 by the load cell 57, calculates the history of the weight reduction (i.e., the variation amount) of the receiving container 54 for each monitoring frequency, and corrects the pump capacity value. Since the weight measurement is performed when the tube pump 53 is not operating, the measurement accuracy can be improved, and the liquid additive 98 can be supplied extremely accurately. In other words, by measuring the weight of the receiving container 54 after the operation of the tube pump 53 each time and averaging the calculated values with the set number of shots, and then feeding back the averaged value to the pump rotation speed, both accuracy and stability can be achieved. Also, when the number of rotors constituting the tube pump 53 is large, the maximum supply amount of the liquid additive 98 per pump rotation becomes small, and the supply accuracy during pump rotation control is improved. On the other hand, when there are many rotors, the tube (flexible tube 41) is likely to wear. However, by correcting with weight control as in this embodiment, the stability and accuracy of the supply of the liquid additive 98 to the resin pellets 99 are improved.

[0059] [Liquid shortage prevention monitoring step S27] As the liquid shortage prevention monitoring step S27, the supply control unit 86 monitors the weight of the receiving container 54 when the pump is not rotating. When it is determined that the weight of the liquid additive 98 in the receiving container 54 has fallen below the set lower limit, the on-off valve 59 is opened, and the liquid additive 98 is supplied to the receiving container 54 until it reaches the set weight. Note that supplying the liquid additive 98 to the receiving container 54 when the pump is rotating makes the pump flow rate of the tube pump 53 unstable, so the liquid additive 98 is not replenished by liquid shortage prevention monitoring. In other words, by replenishing the liquid additive 98 from the filling container 60 when the tube pump 53 is not operating, the stability and accuracy of the weight measurement of the liquid additive 98 filled in the receiving container 54 can be improved, and the stability and accuracy of the supply of the liquid additive 98 by the tube pump 53 can be improved.

[0060] Through the above steps, the injection molding apparatus 1 can accurately and stably add the set amount of the liquid additive 98 to the resin pellets 99.

[0061] <Summary of Features and Functions of Injection Molding Apparatus 1> The features of the injection molding apparatus 1 of this embodiment will be briefly summarized and described. (1) In a molding apparatus (injection molding apparatus 1) including at least an extruder (injection unit 10) having a cylinder 11 in which a screw 19 is provided so as to be drivable in a rotational direction and an axial direction, and a hopper for supplying a resin material (resin pellets 99) to the cylinder 11, a liquid supply device 50 for supplying a liquid additive 98 to be mixed with the resin pellets 99 to the resin pellets 99, a control panel 80 (liquid supply control unit 84) for controlling the supply of the liquid additive 98 to the resin pellets 99 by the liquid supply device 50, a droplet supply port 17 for discharging the liquid additive 89 to a hopper 13 or a path (supply pipe 14) between the hopper 13 and the cylinder 11, a receiving container 54 for storing the liquid additive 98 to be supplied to the liquid supply device 50, having a measuring unit (load cell 57) for measuring the liquid additive 98 stored in the receiving container 54, the control panel 80 (liquid supply control unit 84) has a synchronization control unit 85 (synchronization control function) for synchronizing the timing of supplying the resin pellets 99 to the cylinder 11 and the timing of the liquid supply device 50 supplying the liquid additive 98, and a supply control unit 86 (supply control function) for controlling the supply amount of the liquid additive 98 by the liquid supply device 50 based on the measurement result of the liquid additive 98 by the load cell 57. It has. Since the supply operation of the liquid additive 98 by the liquid supply device 50 is synchronized with the operation of the injection unit 10, the liquid additive 98 can be accurately and stably added to the resin pellets 99. In addition, the liquid additive 98 is temporarily stored in the receiving container 54 provided upstream of the tube pump 53, and the weight of the receiving container 54 is measured by the load cell 57. Therefore, compared with the case of measuring on the downstream side of the tube pump 53, the amount of the liquid additive 98 supplied to the resin pellets 99 can be reliably measured, and the adjustment of the supply amount of the liquid additive 98 becomes accurate. (2) The supply control unit 86 corrects the supply amount of the liquid additive 98 by the liquid supply device 50 based on the difference between the supply amount of the liquid additive 98 set in the liquid supply device 50 and the variation amount of the liquid additive 98 in the receiving container 54 associated with the supply of the liquid additive 98 measured by the load cell 57. For example, even when there is no variation (error) in the operation of the liquid supply device 50 (tube pump 53) itself, if the tube 18 deteriorates due to wear or the like, the liquid additive 98 supplied from the liquid supply device 50 (tube pump 53) may vary (increase). By the supply control unit 86 executing the calibration function, the influence of the measurement variation including the weight variation due to tube deterioration can be eliminated. (3) The liquid supply device 50 has the function of the supply control unit 86 of the control panel 80. The control panel 80 may be configured as one device, or may be provided in different devices according to functions. For example, the supply control unit 86 of the control panel 80 may be provided in the liquid supply device 50. In that case, the liquid supply device 50 executes a calibration function regarding the supply amount of the liquid additive 98 based on the weight variation of the receiving container 54 acquired from the load cell 57. (4) The synchronization control unit 85 synchronizes the timing of the supply of the liquid additive 98 from the liquid supply device 50 with the operation signal for operating the injection unit 10. That is, the synchronization control unit 85 synchronizes the operation of the injection unit 10 and the operation of the liquid supply device 50. For example, the rotation operation (rotation instruction signal) of the screw 19 and the operation signal of the supply operation of the liquid additive 98 by the liquid supply device 50 (tube pump 53) are synchronized. (5) The droplet supply port 17 is a tubular member extending horizontally in the hopper 13 or in the supply pipe 14. (6) The hopper 13 or the supply pipe 14 has a circular cross-sectional shape by a plane perpendicular to the moving direction of the resin pellets 99, The droplet supply port 17 is provided at the center of the circle. (7) The liquid supply control unit 84 of the control panel 80 has a liquid breakage prevention unit 87 that monitors that the suction port (that is, the end 56b of the second liquid feed pipe 56) when the liquid supply device 50 sucks the liquid additive 98 from the receiving container 54 is inside the liquid additive 98 stored in the receiving container 54. (8) A filling container 60 (pack) filled with the liquid additive 98 can be attached, It has an on-off valve 59 that opens and closes the path for supplying from the filling container 60 to the receiving container 54, The control panel 80 controls the on-off (opening and closing) of the on-off valve 59. (9) The liquid supply device 50 has a tube pump 53 that transports the liquid additive 98 to the droplet supply port 17. (10) The droplet supply port 17 is composed of a tubular member made of a resin material having a glass transition temperature Tg of 100 °C or higher. (11) The droplet supply port 17 is composed of a tubular member made of a metal member.

[0062] The embodiments of the present invention have been described above, but these are examples of the present invention, and various configurations other than the above can also be adopted.

[0063] With reference to FIGS. 8 and 9, a modified example of the configuration of the hopper 13 and the adapter 16 will be described. Hereinafter, the hopper body 13a is an inverted cone, and the cylindrical portion 13b and the supply pipe 14 are exemplified as cylinders. Also, the resin supply path in the hopper 13, the supply pipe 14, and the adapter 16 is indicated by a broken line.

[0064] In Fig. 8(a), a configuration is shown in which an adapter 16 is disposed between the cylindrical portion 13b of the hopper 13 and the supply pipe 14. The tip 17a of the droplet supply port 17 attached to the adapter 16 is at a position shifted toward the path surface side from the center of the resin supply path having a circular cross-section in the adapter 16. In Fig. 8(b), in the configuration of Fig. 8(a), the tip 17a of the droplet supply port 17 is centered on the resin supply path.

[0065] In Fig. 8(c), the adapter 16 has a disk-shaped flange portion 16a, a pipe portion 16b above the flange portion 16a, and a portion 16c below the flange portion 16a. A resin supply path communicating vertically is provided at the center of the adapter 16. The upper pipe portion 16b is connected to the cylindrical portion 13b of the hopper 13, and the lower pipe portion 16c is connected to the supply pipe 14. The droplet supply port 17 is attached to the flange portion 16a.

[0066] In Fig. 8(d), the adapter 16 has a disk-shaped flange portion 16a and a portion 16c below the flange portion 16a. A resin supply path communicating vertically is provided at the center of the adapter 16. The upper surface of the flange portion 16a is connected to the cylindrical portion 13b of the hopper 13, and the lower pipe portion 16c is connected to the supply pipe 14. The droplet supply port 17 is attached to the flange portion 16a.

[0067] In Fig. 8(e), the adapter 16 is omitted, and the cylindrical portion 13b of the hopper 13 is directly connected to the supply pipe 14. The droplet supply port 17 is attached to the cylindrical portion 13b of the hopper 13.

[0068] In Fig. 8(f), in the configuration of Fig. 8(d), the supply pipe 14 is omitted, and the pipe portion 16c below the flange portion 16a is directly connected to the cylinder 11.

[0069] Figs. 9(a) to 9(d) show a configuration in which, in the configuration of the hopper 13 shown in Figs. 8(a) to 8(d), the cylindrical portion 13b is omitted and the hopper body 13a is connected to the adapter 16.

Explanation of reference numerals

[0070] 1 Injection Molding Device 10 Injection Unit 11 Cylinder 12 Injection Nozzle 13 Hopper 13a Hopper Body 13b Cylindrical Part 14 Supply Pipe 15 Heater 16 Adapter 16a Flange Part 16b, 16c Cylindrical Parts 17 Droplet Supply Port 18 Tube 19 Screw 20 Driving Part 30 Mold Clamping Unit 31 Preform Mold 32 Pot Mold 33 Blow Mold 50 Liquid Supply Device 51 Weighing Instrument 52 Measuring Chamber 53 Tube Pump 54 Receiving Container 55 First Liquid Delivery Pipe 56 Second Liquid Delivery Pipe 57 Load Cell 58a, 58b Joint 59 On - Off Valve 60 Filling Container 71 Preform 73 Molded Product 95 Air 98 Liquid Additive 99 Resin Pellet

Claims

1. In a molding apparatus including at least an extruder having a cylinder in which a screw is provided so as to be drivable in a rotational direction and an axial direction, and a hopper for supplying a resin material to the cylinder, a droplet supply device for supplying a liquid additive to be mixed with the resin material to the resin material, a control unit for controlling the supply of the liquid additive to the resin material by the droplet supply device, a supply port for discharging the liquid additive in the hopper or a path between the hopper and the cylinder, a container for storing the liquid additive to be supplied to the droplet supply device, a measuring unit for measuring the liquid additive stored in the container, wherein the control unit has a synchronization control function for synchronizing the timing of supplying the resin material to the cylinder and the timing of supplying the liquid additive by the droplet supply device, and a supply control function for controlling the supply amount of the liquid additive by the droplet supply device based on the measurement result of the liquid additive by the measuring unit, and is capable of mounting a pack filled with the liquid additive, has an on-off valve in a path for supplying from the pack to the container, and the control unit controls the on-off of the on-off valve, a molding apparatus.

2. The supply control function corrects the supply amount of the liquid additive by the droplet supply device based on the difference between the supply amount of the liquid additive set in the droplet supply device and the variation amount of the liquid additive in the container accompanying the supply of the liquid additive measured by the measuring unit. The molding apparatus according to Claim 1.

3. The droplet supply device has the supply control function of the control unit. The molding apparatus according to Claim 1 or 2.

4. The synchronization control function interlocks the timing of supplying the liquid additive from the droplet supply device with an operation signal for operating the extruder. The molding apparatus according to any one of Claims 1 to 3.

5. The supply port is a tubular member extending horizontally in the hopper or in the path. The molding apparatus according to any one of Claims 1 to 4.

6. The hopper or the path has a circular cross-sectional shape by a plane perpendicular to the moving direction of the resin material, and the supply port is provided at the center of the circle. The molding apparatus according to any one of Claims 1 to 5.

7. The molding apparatus according to any one of claims 1 to 6, wherein the control unit has a liquid breakage prevention function of monitoring that a suction port when the liquid droplet supply device sucks the liquid additive from the container is inside the liquid additive stored in the container.

8. The molding apparatus according to any one of claims 1 to 7, wherein the liquid droplet supply device has a tube pump that transports the liquid additive to the supply port.

9. The molding apparatus according to any one of claims 1 to 8, wherein the supply port is a tubular member made of a resin material having a glass transition temperature Tg of 100°C or higher.

10. The molding apparatus according to any one of claims 1 to 8, wherein the supply port is a tubular member made of a metal member.

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