JP7698263B2 - Molding equipment - Google Patents

Description

The present invention relates to a molding device that uses an extruder to inject resin material into a mold to form it.

In a molding apparatus for injection molding or blow molding, as an example, a technique is known in which a resin material (resin pellets or resin powder) is mixed with a liquid additive (a high-concentration pigment dispersion or a plastic additive dispersion) during each molding shot.
For example, a technique has been proposed for producing colored molded products by supplying raw resin and microencapsulated liquid color as a colorant at a constant ratio to a material supply hopper of an injection molding machine (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 3-199021

Accurate metering is required when adding liquid additives to resin materials. For example, when the liquid additive is a colorant, even a slight fluctuation in the supply amount can cause a difference in color in the product. Furthermore, even if an appropriate supply amount is set at the beginning, it can gradually change, so there is a need to improve the stability of the supply amount of liquid additives.
The technique disclosed in Patent Document 1 does not disclose any technique from the viewpoint of improving the stability of the supply amount of the liquid additive, and a new technique has been desired.

The present invention has been developed in consideration of these circumstances, and aims to provide a technology that achieves both accuracy and stability in the supply amount of liquid additive added to a resin material in a molding device that molds the resin material using an extruder.

According to the present invention, there is provided 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 liquid droplet supplying device that supplies a liquid additive to be mixed with the resin material to the resin material;
a control unit that controls the supply of the liquid additive to the resin material by the droplet supplying device;
a supply port through which the liquid additive is discharged into the hopper or into a path between the hopper and the cylinder;
A container for storing the liquid additive to be supplied to the liquid droplet supplying device;
A measuring unit for measuring the liquid additive stored in the container,
The control unit is
a synchronization control function for synchronizing a timing at which the resin material is supplied to the cylinder with a timing at which the liquid droplet supplying device supplies the liquid additive;
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 measurement unit;
A molding apparatus having a

The present invention provides a technology that achieves both accuracy and stability in the supply amount of liquid additive added to a resin material in a molding device that molds the resin material using an extruder.

1 is a schematic diagram showing a schematic configuration of an injection molding apparatus according to an embodiment. FIG. 2 is a schematic diagram showing a schematic configuration of an injection unit according to the embodiment. 1 is a schematic diagram showing a schematic configuration of an adapter installed in a supply pipe according to an embodiment; 1 is a schematic diagram showing a schematic configuration of a liquid supply apparatus according to an embodiment. FIG. 2 is a functional block diagram of a control panel according to the embodiment. 4 is a flowchart showing an example of an injection molding operation according to the embodiment. 4 is a timing chart showing a rotation time of a screw, a supply time of resin pellets to a cylinder, and a pump operation time according to an embodiment. 13A and 13B are diagrams illustrating modified configurations of a hopper and an adaptor according to a modified example of the embodiment. 13A and 13B are diagrams illustrating modified configurations of a hopper and an adaptor according to a modified example of the embodiment.

An embodiment of the present invention will be described with reference to the drawings.
<Outline of injection molding apparatus 1>
1 is a schematic diagram showing the general configuration of an injection molding apparatus 1, and is shown as a cross-sectional view so that the internal structure can be seen. In this embodiment, an injection molding apparatus 1 that performs so-called injection blow molding is illustrated as an example, but the present invention is not limited to this and can be applied to an apparatus that performs molding by injection using an extruder, such as general injection molding, extrusion molding, compression molding, and press molding.
First, the injection unit 10 and the injection molding process will be outlined.

The injection molding device 1 has an injection unit 10, a clamping unit 30, a liquid supply device 50, and a control panel 80 that controls them. In the injection unit 10, resin pellets 99 and liquid additives 98 supplied to a hopper 13 are mixed in a cylinder 11 and injected from an injection nozzle 12 into the clamping unit 30.

Resin pellets 99 are a molding material for thermoplastic plastics (resin), made by melting and kneading resin material with various composite materials (additives), and generally have a small spherical or cylindrical shape.

The liquid additive 98 is a colorant such as a liquid color, but may also be any of a variety of liquid additives to be added to the resin pellets 99, or a liquid additive in which a solid additive is dispersed.

The liquid additive 98 is filled into the filling container 60 and supplied to the liquid supply device 50. Here, the liquid additive 98 is once stored in the receiving container 54 from the filling container 60. Furthermore, 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. The filling container 60 is preferably a deformable pouch container or a container with an opening that functions as a spout or an air hole so that the liquid additive 98 can fall by gravity into the receiving container 54. In this embodiment, a pouch container is exemplified as the filling container 60.

In the mold clamping unit 30, the preform mold 31 is filled with the resin material (a mixture of resin pellets 99 and liquid additive 98) injected from the injection unit 10, and an intermediate molded product called a preform 71 is formed (injection process).

Next, the preform 71 is attached to the pot mold 32, and the preform 71 is partially heated in preparation for the next blowing process (temperature control process). For example, if the finished product is a bottle, the mouth part is controlled to a low temperature so as not to stretch, other stretching parts are controlled to a high temperature, and parts where it is desired to make the wall thinner are partially heated at an even higher temperature. 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, forming a molded product 73 of the desired shape, which is then removed from the blow mold 33 as a finished product (blow process).

<Injection unit 10>
FIG. 2 is a cross-sectional view showing a schematic configuration of the injection unit 10. As shown in FIG.
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 .

A screw 19 is arranged inside the cylinder 11 along the axial direction so that it can be driven in both the rotational and axial directions. The screw 19 is driven in both the rotational and axial directions by a drive unit 20. The operation of the drive unit 20 is controlled by a control panel 80.

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

The hopper 13 has a so-called funnel shape with an inverted cone-shaped hopper body 13a and a cylindrical tube section 13b provided below it, and resin pellets 99 are poured into the upper opening. There are no particular limitations on the shape of the cone (inverted cone), but it can generally be a circular cone or a square pyramid. The tube section 13b of the hopper 13 is connected to the supply pipe 14.

Figure 3 is a schematic perspective view of the adapter 16 attached to the supply pipe 14. The supply pipe 14 connects the hopper 13 and the cylinder 11, and supplies the resin pellets 99 put into the hopper 13 to the cylinder 11. The shape of the supply pipe 14 can be, for example, a cylinder with a circular cross section. The inside of the cylinder functions as the resin supply path 14a. In general, the shape is determined in consideration of 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 tube, the supply pipe 14 is a square tube, but the shapes are not limited to these and can also be other polygonal shapes. Here, a cylindrical supply pipe 14 is shown as an example.

A droplet supply port 17 is provided in the resin supply path between the hopper 13 and the cylinder 11 to supply the liquid additive 98 to the resin pellets 99. "In the resin supply path" means that it may be provided at the boundary between the hopper 13 (tubular portion 13b) and the supply pipe 14, or may be provided in the supply pipe 14. Here, an adapter 16 provided with a 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 from above to below. 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 form a single resin supply path that extends vertically.

The droplet supply port 17 is a tubular member that communicates with the inside of the resin supply path 14b from the outside of the adapter 16 and 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 17b of the droplet supply port 17 located outside the adapter 16.

The tip 17a of the droplet supply port 17 is arranged so as to be the center of the circle of the resin supply path 14b (the inside of the supply pipe 14). That is, the liquid additive 98 is supplied to the resin pellets 99 at the center of the resin supply path 14b. If the resin supply path 14b is rectangular, the tip 17a of the droplet supply port 17 is arranged so that the intersection of the diagonal lines is the tip 17a of the droplet supply port 17. This can prevent the resin pellets 99 and the liquid additive 98 from being mixed unevenly. 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 is not reduced. For example, a cover having an inverted V-shaped cross section can be used.

The droplet supply port 17 (tubular member) may be made of a metal material (such as aluminum, copper, or stainless steel), a resin material, or a composite material thereof, but is not limited thereto, and may be made of any material that has a certain strength against the flow of the resin pellets 99 and is heat resistant to the heated resin pellets 99. In the case of a resin material, it is preferable that the material has a glass transition temperature Tg of 100°C or higher from the viewpoint of heat resistance. The inner diameter of the droplet supply port 17 is appropriately set depending on the required supply speed of the liquid additive 98.

<Liquid supply device 50>
FIG. 4 is a perspective view showing a schematic configuration of the liquid supply device 50. As shown in FIG.
The liquid supplying device 50 includes a weight measuring device 51, a tube pump 53, a receiving container 54, a first liquid feed pipe 55 and a second liquid feed pipe 56 as transport paths for the liquid additive 98, and an on-off valve 59. With this configuration, the liquid supplying 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 measuring chamber 52, so that the liquid additive 98 can flow down by gravity.

The weight measuring device 51 has a weighing chamber 52 with a load cell 57 inside. A receiving container 54 is provided above 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 control panel 80 of the measurement result. An elastic member (seismic rubber) for vibration control may be placed below the load cell 57.

The upper part of the measuring chamber 52 has a first liquid delivery pipe 55 that delivers the liquid additive 98 from the filling container 60 to the receiving container 54, and a second liquid delivery pipe 56 that delivers the liquid additive 98 from the receiving container 54 to the tube pump 53.

The upper end 55a of the first liquid feed tube 55 is attached to the filling container 60. The lower end 55b of the first liquid feed tube 55 is at a predetermined height from the bottom surface of the receiving container 54. The first liquid feed tube 55 is provided with an on-off valve 59, and the flow path is controlled by the control panel 80 to control the supply of the liquid additive 98 filled in the filling container 60 to the receiving container 54. Here, the on-off valve 59 (i.e., the flow path of the first liquid feed tube 55) is normally closed by a spring, and by transmitting an open signal, 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 (off), the on-off valve 59 closes the flow path by the spring, and the supply of the liquid additive 98 is stopped. The on-off valve 59 can be opened and closed by a simple control of only an open or close signal, but this control method is not limited to this, and other controls may be used. Other configurations that can be used as the on-off valve 59 include a combination of a solenoid and a spring, an air cylinder, a pinch cock, etc.

One end 56b of the second liquid feed pipe 56 is at a predetermined height from the bottom surface of the receiving container 54. The other end 56a of the second liquid feed pipe 56 is attached to the flexible tube 41 of the tube pump 53 via a 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 feed pipe 56 and supplies a set amount to the hopper 13.

There are no particular limitations on the materials used for the first liquid transfer tube 55 and the second liquid transfer tube 56, but from the standpoint of durability, chemical resistance, heat resistance, etc., a fluororesin tube, for example, can be used.

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

A plurality of rollers are attached to the outer periphery of the rotor, which partially presses the flexible tube 41 against the inner wall of the housing, etc., and the liquid additive 98 in the receiving container 54 is delivered to the hopper 13 by the rotation of the rotor.
That is, in synchronization with the drive of the injection unit 10 (for example, a signal that causes the drive unit 20 to drive the screw 19), the tube pump 53 is driven to deliver the liquid additive 98 (for example, liquid color) from the receiving container 54 to the hopper 13.

The flexible tube 41, the above-mentioned tube 18, the first liquid feed pipe 55, and the second liquid feed pipe 56 are replaced for each type of liquid additive 98 used in order to prevent contamination of the liquid additive 98. In addition, multiple flexible tubes 41 may be attached to the tube pump 53 in parallel. In that case, multiple tubes 18, the first liquid feed pipe 55, and the second liquid feed pipe 56 connected to the flexible tube 41 may be connected, or may be joined midway by a joint mechanism.

In this way, by using the tube pump 53, it is possible to achieve both accuracy and stability in the supply amount of the liquid additive 98. In addition, 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, it is possible to measure the liquid additive 98 with high accuracy without causing fluctuations in the amount of the liquid additive 98 supplied to the resin pellets 99, compared to the case of measuring the liquid additive 98 downstream of the tube pump 53. In other words, unlike a configuration in which a flow meter or the like is disposed downstream of the tube pump 53, the path from the tube pump 53 to the droplet supply port 17 can be simplified, and from this viewpoint as well, it is possible to achieve both stability and accuracy in the supply amount of the liquid additive 98.
In addition, since the load cell 57 is disposed upstream of the tube pump 53 and away from the injection unit 10, which is a heat source, it is not affected by temperature changes due to the viscosity and density of the liquid additive 98, and stable and accurate measurement can be achieved.

<Control Panel 80>
5 is a functional block diagram showing a schematic configuration of the control board 80. The control board 80 can be configured with, for example, a processor such as an MPU (Micro Processing Unit), a memory such as a ROM (Read Only Memory) or a RAM (Random Access Memory), and an output device such as an audio output device or 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 board 80 may be configured as a single device, or may be configured as multiple devices.

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).

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

The injection control unit 83 controls the injection process and the blow process performed by the injection unit 10 and the mold clamping unit 30 .
The injection control unit 83 controls the drive unit 20 to rotate and advance the screw 19 in the cylinder 11, and also injects the resin pellets 99 fed 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.

Furthermore, the injection control unit 83 performs a temperature control process for the mold clamping unit 30 to partially heat the preform 71 obtained in the injection process, and as a blow molding process, attaches the preform 71 after temperature control to the blow mold 33 and blows air 95 into the inside of the preform 71 to mold a molded product 73 of the desired shape.

The liquid supply control unit 84 has a synchronization control unit 85, a supply control unit 86, and a liquid shortage prevention unit 87.

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

The supply control unit 86 monitors the fluctuation in weight 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 so that it is the set amount.
Specifically, the monitoring frequency during molding is set by operating the control panel 80, and the weight fluctuation of the receiving container 54 by the load cell 57 is monitored during molding, and the weight fluctuation is 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. The monitoring frequency (number of shots) is selected from six levels, for example, "10, 20, 30, 40, 50, and 100 shots." Furthermore, the upper and lower limits of the weight of the liquid additive 98 that can be filled in the receiving container 54 are set.
This allows appropriate adjustments to be made even if the supply amount of the tube pump 53 differs from the setting due to wear of the flexible tube 41 used in the tube pump 53 caused by the discharge operation of the tube pump 53, thereby achieving a highly accurate supply of the liquid additive 98.

As a function of preventing liquid shortage, the liquid shortage 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 reason, an upper and lower limit are set in the monitoring setting for the liquid amount of the liquid additive 98 filled into the receiving container 54. When the set lower limit amount of liquid additive 98 is filled, the end 56b of the second liquid delivery pipe 56 is always inside the liquid additive 98.

<Operation of Injection Molding Apparatus 1>
6 is a flow chart showing an example of the injection molding operation of the injection molding apparatus 1. Here, the operation of the injection unit 10 will be described, focusing in particular on the supply operation of the liquid additive 98 by the liquid supply device 50.
The operation of the injection molding apparatus 1 broadly includes an initial setting S10 of the liquid supply device 50, and an injection molding step S20 by the injection unit 10 and the mold clamping unit 30 based on the initial setting. This will be described in detail below.

<Initial Settings S10 of Liquid Supply Apparatus 50>
The initial setting S10 of the liquid supplying device 50 includes a tube installation step S11, a liquid filling step S12, a calibration step S13, and a molding preparation step S14.

[Tube installation step S11]
A cleaned (or new) flexible tube 41 is installed in the tube pump 53, and cleaned (or new) tubes 18, a first liquid feed pipe 55, and a second liquid feed pipe 56 are also installed. Note that the tube 18 is in a state of being removed from the droplet supply port 17 of the adapter 16.

[Liquid agent filling step S12]
Next, the receiving container 54 is placed on the load cell 57. At this time, the lower end 55b of the first fluid feed pipe 55 and the lower end 56a of the second fluid feed pipe 56 are placed in the receiving container 54. At this time, the end 56b of the second fluid feed pipe 56 is set to a predetermined height from the receiving container 54 in order to prevent 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.
In addition, upper and lower limits are set by monitoring the amount of liquid additive 98 filled into 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 within the liquid additive 98.
Next, the control panel 80 is operated to turn on (open) the on-off valve 59, and the liquid additive 98 is filled into the receiving container 54. Furthermore, with the tube 18 removed from the droplet supply port 17 of the adapter 16, the tube pump 53 is rotated to fill the tube 18 and the flexible tube 41 with the liquid additive 98.

[Calibration step S13]
The calibration is performed by rotating the tube pump 53 at, for example, 50% of its pumping capacity for a certain period of time, and determining the pumping capacity value from the weight loss in the receiving vessel 54, the number of revolutions, and the time.

[Molding preparation step S14]
After the calibration is completed, the tube 18 is connected to the droplet supply port 17 of the adapter 16, and various molding conditions are set by operating the control panel 80. Specifically, the control panel 80 is operated to input the amount of resin (amount of resin pellets 99) required for one shot of molding and the addition rate of the liquid additive 98, and the amount of the liquid additive 98 to be added to the resin pellets 99 is set. More specifically, the pump speed of the tube pump 53 is calculated from the time taken for the screw 19 to rotate, taking into consideration the timing at which the resin pellets 99 are fed into the hopper 13 and the timing at which the liquid additive 98 is discharged from the droplet supply port 17, the pump capacity of the tube pump 53, and the amount of the liquid additive 98 added. At this time, since it is necessary to obtain the pump speed in advance, the time taken for the screw 19 to rotate is measured in advance, and the pump speed is determined using the measured value for the first injection molding. In this process, it is preferable to actually operate the injection molding apparatus 1 and measure and reflect the measurement results, but if there is a measurement history, or more specifically, if there is little variation in the measurement history, it is also possible to only perform setting without measuring.

Next, the monitoring frequency during molding is set. The monitoring frequency (number of shots) is selected from six levels, for example, "10, 20, 30, 40, 50, and 100 shots." Furthermore, the upper and lower limits of the weight of the liquid additive 98 that can be filled in the receiving vessel 54 are set.
Also, the synchronization timing between the injection unit 10 and the liquid supply device 50 is set. Here, the time after (or before) the operation timing of the injection unit 10 (extruder) is set as to how many seconds after (or how many seconds before) the tube pump 53 is operated. The signal of the injection unit 10 (i.e., the supply of the resin pellets 99) and the operation of the liquid supply device 50 are synchronized, but at this time, it is 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). To deal with such a case, the liquid supply device 50 can set the gap in 0.1 second increments, for example, between 0 and 5.0 seconds.

Figure 7 shows a timing chart of the rotation time of the screw 19, the supply time of resin pellets 99 (labeled "resin" in the figure) to the cylinder 11, and the pump operation time. Here, the rotation time of the screw 19 is set to 10 seconds, and an example is shown in which the synchronization timing of the supply time of resin pellets 99 to the rotation time of the screw 19 (hereinafter referred to as "resin supply time") and the pump operation time is set. Here, the resin supply time and the pump operation time are set to match. As the synchronization timing, a "delay time" from the start of rotation of the screw 19 and a "shortened time" for the rotation time of the screw 19 are set.

Figure 7(a) shows an example where the "delay time" is set to "1.0 second" and the "shortened time" is set to "1.0 second." With this setting, since there is a delay gap of 1.0 second in the start timing between the rotation signal of the screw 19 and the resin supply time, the tube pump 53 is set to start operating 1 second late. In addition, the stop timing of the tube pump 53 is set 1 second shorter than the rotation time of the screw 19.

Figure 7 (b) shows an example where the "delay time" is set to "1.0 second" and the "reduced time" is set to "0 second" (no change). With this setting, the start of operation of the tube pump 53 is delayed by 1.0 second from the rotation signal of the screw 19. In addition, the timing for stopping the tube pump 53 is set to the same timing as the rotation time of the screw 19.

7C shows an example in which the "delay time" is set to "0 seconds" (no change) and the "shortened time" is set to "1.0 second." According to this setting, the tube pump 53 is set to start operating simultaneously with the rotation signal of the screw 19. In addition, the timing for stopping the tube pump 53 is set to be 1.0 second shorter than the rotation time of the screw 19.
In the above description, the resin supply time and the pump operation time coincide with each other, but the resin supply time and the pump operation time may be set separately.

In this way, by synchronizing the timing of supplying the resin pellets 99 to the cylinder 11 with the timing of supplying the liquid additive 98, the liquid additive 98 spreads evenly over the resin pellets 99, improving accuracy.

<Injection molding process S20 (operation during molding)>
[Volume measuring 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 liquid additives 98 supplied to the hopper 13 by rotating the screw 19 inside the cylinder 11, collects them at the tip of the cylinder 11, and measures the volume of the melt-kneaded raw materials (i.e., the resin pellets 99 and the liquid additives 98) (volume measuring process S21).
By pushing the screw 19 forward, the measured raw materials (resin pellets 99 and liquid additive 98) are injected from the injection nozzle 12 into the preform mold 31 of the mold clamping unit 30, to obtain the preform 71 (injection step S22).
The preform 71 is attached to the pot mold 32, and partially heated in preparation for the next blowing step (temperature control step S23). For example, if the finished product is a bottle, the mouth part is controlled to a low temperature so as not to stretch, the other stretching parts are controlled to a high temperature, and the parts where it is desired to make the wall thickness thinner are partially heated to an even higher temperature. 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 forming a molded product 73 of the desired shape, and the molded product 73 is taken out of the blow mold 33 as a finished product (blow step S24).

[Liquid additive supply step S25]
When the injection molding process S20 is started, the liquid supply control unit 84 of the control panel 80 executes the liquid additive supply process S25 in synchronization with the volume measuring process S21. 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, operates the tube pump 53 of the liquid supply device 50 at a pump rotation speed calculated from the pump capacity and the amount of liquid added, 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 to continue to supply the liquid additive 98 from the liquid supply device 50 while the resin pellets 99 are being supplied in one injection molding, and when the supply of the resin pellets 99 for injection molding stops, the tube pump 53 also stops. This allows the liquid supply device 50 to stably add the liquid additive 98 to the resin pellets 99.

[Pump value correction step S26]
The liquid supply control unit 84 of the control panel 80 executes the pump value correction step S26 while the supply of the liquid additive 98 by the liquid supply device 50 is stopped, that is, while the tube pump 53 is stopped. 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 loss (i.e., the amount of fluctuation) of the receiving container 54 for each monitoring frequency, and corrects the pump capacity value. Since the weight is measured 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, the weight of the receiving container 54 after the operation of the tube pump 53 is measured every time, and the calculated value averaged over the set number of shots is fed back to the pump rotation speed, thereby achieving both accuracy and stability. In addition, if 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 increases. On the other hand, if there are many rotors, the tube (flexible tube 41) becomes more likely to wear. However, by performing correction by weight control as in this embodiment, the stability and accuracy of supplying the liquid additive 98 to the resin pellets 99 is improved.

[Liquid Outage Prevention Monitoring Step S27]
In the liquid run-out prevention monitoring step S27, the supply control unit 86 monitors the weight of the receiving container 54 while the pump is not rotating, and when it is determined that the weight of the liquid additive 98 in the receiving container 54 falls below the set lower limit, it opens the on-off valve 59 and supplies the liquid additive 98 to the receiving container 54 until the set weight is reached. Note that if the liquid additive 98 is supplied to the receiving container 54 while the pump is rotating, the pump flow rate of the tube pump 53 becomes unstable, so that the liquid additive 98 is not replenished by the liquid run-out prevention monitoring. In other words, by replenishing the liquid additive 98 from the filling container 60 while 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.

Through the above process, the injection molding device 1 can accurately and stably add a set amount of liquid additive 98 to the resin pellets 99.

<Summary of features and functions of injection molding device 1>
The features of the injection molding apparatus 1 of this embodiment will be briefly summarized and described.
(1) 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 supplying device 50 that supplies 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) that controls 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 a liquid additive 89 into the hopper 13 or into a path (supply pipe 14) between the hopper 13 and the cylinder 11;
a receiving vessel 54 for storing a liquid additive 98 to be supplied to the liquid supply device 50;
A measuring unit (load cell 57) for measuring the liquid additive 98 stored in the receiving container 54 is provided.
The control panel 80 (liquid supply control unit 84)
a synchronization control unit 85 (synchronization control function) that synchronizes the timing of supplying the resin pellets 99 to the cylinder 11 with the timing of supplying the liquid additive 98 by the liquid supply device 50;
a supply control unit 86 (supply control function) that controls 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;
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 added to the resin pellets 99 accurately and stably.
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, the amount of liquid additive 98 to be supplied to the resin pellets 99 can be reliably measured compared to the case where it is measured downstream of the tube pump 53, and the supply amount of liquid additive 98 can be accurately adjusted.
(2) The supply control unit 86 calibrates the amount of liquid additive 98 supplied by the liquid supply device 50 based on the difference between the amount of liquid additive 98 set in the liquid supply device 50 and the amount of fluctuation in the liquid additive 98 in the receiving container 54 due to the supply of the liquid additive 98 measured by the load cell 57.
For example, even if there is no variation (error) in the operation of the liquid supply device 50 (tube pump 53) itself, as deterioration such as wear progresses in the tube 18, there may be a variation (increase) in the liquid additive 98 supplied from the liquid supply device 50 (tube pump 53). By having the supply control unit 86 execute the calibration function, it is possible to eliminate the influence of measurement variations, including weight variations due to tube deterioration.
(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 depending on the function. 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 performs a calibration function regarding the supply amount of the liquid additive 98 based on the weight fluctuation of the receiving container 54 obtained 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 that operates the injection unit 10 .
That is, the synchronization control unit 85 synchronizes the operation of the injection unit 10 with the operation of the liquid supply device 50. For example, the synchronization control unit 85 synchronizes the rotation operation (rotation instruction signal) of the screw 19 with the operation signal of the supply operation (tube pump 53) of the liquid supply device 50 to supply the liquid additive 98.
(5) The droplet supply port 17 is a tubular member extending horizontally within the hopper 13 or the supply pipe 14 .
(6) The hopper 13 or the supply pipe 14 has a circular cross-sectional shape taken along a plane perpendicular to the moving direction of the resin pellets 99.
The droplet supply port 17 is provided in the center of the circle.
(7) The liquid supply control unit 84 of the control panel 80 has a liquid shortage prevention unit 87 that monitors whether the suction port (i.e., the 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 inside the liquid additive 98 stored in the receiving container 54.
(8) A filling container 60 (pack) filled with a liquid additive 98 can be attached,
an on-off valve 59 for opening and closing a path for supplying the liquid from the filling container 60 to the receiving container 54;
The control panel 80 controls the on/off (opening/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 made 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 made of a tubular member made of a metal material.

The above describes embodiments of the present invention, but these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

With reference to Figures 8 and 9, modified examples of the configuration of the hopper 13 and the adapter 16 will be described. In the following, the hopper body 13a is illustrated as an inverted cone, and the tube portion 13b and the supply pipe 14 are illustrated as cylinders. In addition, the resin supply paths in the hopper 13, the supply pipe 14, and the adapter 16 are indicated by dashed lines.

Figure 8(a) shows a configuration in which an adapter 16 is placed 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 located at a position offset toward the path surface from the center of the resin supply path, which has a circular cross section, in the adapter 16. Figure 8(b) shows a configuration in which the tip 17a of the droplet supply port 17 is the center of the resin supply path in the configuration of Figure 8(a).

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 pipe portion 16c below the flange portion 16a. A resin supply path that communicates vertically is provided in 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.

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 that communicates from top to bottom is provided in the center of the adapter 16. The top 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.

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.

In Figure 8(f), the supply pipe 14 is omitted from the configuration in Figure 8(d), and the pipe section 16c below the flange section 16a is directly connected to the cylinder 11.

Figures 9(a) to 9(d) show the configuration of the hopper 13 shown in Figures 8(a) to 8(d), except that the cylindrical portion 13b is omitted and the hopper body 13a is connected to the adapter 16.

1 Injection molding apparatus 10 Injection unit 11 Cylinder 12 Injection nozzle 13 Hopper 13a Hopper body 13b Cylindrical portion 14 Supply pipe 15 Heater 16 Adapter 16a Flange portion 16b, 16c Cylindrical portion 17 Liquid droplet supply port 18 Tube 19 Screw 20 Drive unit 30 Mold clamping unit 31 Preform mold 32 Pot mold 33 Blow mold 50 Liquid supply device 51 Weight measuring device 52 Measuring chamber 53 Tube pump 54 Receiving container 55 First liquid feed pipe 56 Second liquid feed pipe 57 Load cell 58a, 58b Joint 59 Opening and closing valve 60 Filling container 71 Preform 73 Molded product 95 Air 98 Liquid additive 99 Resin pellets

Claims (10)

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 liquid droplet supplying device that supplies a liquid additive to be mixed with the resin material to the resin material;
a control unit that controls the supply of the liquid additive to the resin material by the droplet supplying device;
a supply port for discharging the liquid additive into the hopper or into a passage between the hopper and the cylinder;
A container for storing the liquid additive to be supplied to the liquid droplet supplying device;
A measuring unit for measuring the liquid additive stored in the container,
The control unit is
a synchronization control function for synchronizing a timing at which the resin material is supplied to the cylinder with a timing at which the liquid droplet supplying device supplies the liquid additive;
a supply control function for controlling the amount of the liquid additive supplied by the droplet supply device based on the measurement result of the liquid additive by the measurement unit;
having
A pack filled with the liquid additive can be attached,
an on-off valve for supplying a supply from the pack to the container;
The control unit controls the on/off of the on-off valve . The molding device according to claim 1, wherein the supply control function calibrates the amount of the liquid additive supplied by the droplet supply device based on the difference between the amount of the liquid additive supplied set in the droplet supply device and the amount of the liquid additive fluctuation in the container caused by the supply of the liquid additive measured by the measuring unit. The molding device according to claim 1 or 2, wherein the droplet supply device is provided with the supply control function of the control unit. The molding device according to any one of claims 1 to 3, wherein the synchronization control function synchronizes the timing of the supply of the liquid additive from the droplet supply device with an operation signal that operates the extruder. The molding device according to any one of claims 1 to 4, wherein the supply port is a tubular member extending horizontally within the hopper or the path. The hopper or the path has a circular cross-sectional shape taken along a plane perpendicular to a moving direction of the resin material,
The molding apparatus according to claim 1 , wherein the supply port is provided at the center of the circle. The molding device according to any one of claims 1 to 6, wherein the control unit has a liquid shortage prevention function that monitors whether the suction port when the droplet supplying device sucks the liquid additive from the container is inside the liquid additive stored in the container. The molding apparatus according to claim 1 , wherein the droplet supplying device has a tube pump that transports the liquid additive to the supply port. 9. The molding apparatus according to claim 1 , wherein the supply port is a tubular member made of a resin material having a glass transition temperature Tg of 100[deg.] C. or higher. The molding apparatus according to claim 1 , wherein the supply port is a tubular member made of a metal material.

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