JP2020157635A - Injection molding machine - Google Patents

Abstract

To provide an injection molding machine capable of suppressing a reduction of an action of additives while eliminating an adverse effect of volatile components generated when a molding material is melted and transported.SOLUTION: This injection molding machine includes: an injection device that melts and injects a molding material; a takeout unit (71) that takes out a volatile component of the molding material melted by the injection device; and a return unit (76, 77, 78) that returns the volatile component taken out from the takeout unit to the molten molding material from a position different from the takeout unit.SELECTED DRAWING: Figure 2

Description

The present invention relates to an injection molding machine.

In an injection molding machine, in general, an additive that exerts various properties and functions on a molded product is added to a molding material, and the molding material is melted and injection molded. Additives have lower molecules than molding materials, which are resins, and volatilize at lower temperatures. Additives are usually pelletized with the molding material and charged from the hopper with the molding material.

Patent Document 1 discloses an injection molding machine configured such that an inert gas is injected into a high-pressure area of a cylinder and the inert gas is degassed in the low-pressure area.

Japanese Patent No. 5710813

The additive that is conveyed to the nozzle side together with the molding material in the cylinder has a problem that a part of the additive is volatilized and the volatilized component is exposed to a high temperature, so that the component is altered. Further, when the volatile component is cooled in the vicinity of the hopper or the supply port of the material, the volatile component is concentrated, and there arises a problem that the concentrated component adheres to the resin material.

On the other hand, as shown in Patent Document 1, any component volatilized in the cylinder can be degassed using an inert gas. However, since the volatile component contains an additive component, if the volatile component is degassed, there arises a problem that the action of the additive is reduced.

An object of the present invention is to provide an injection molding machine capable of suppressing a reduction in the action of an additive while eliminating an adverse effect of a volatile component generated when a molding material is melted and transported.

The present invention
An injection device that melts and injects molding material,
An extraction unit that takes out the volatile components of the molding material melted by the injection device, and
A return portion that returns the volatile component taken out from the take-out portion to the molten molding material from a position different from that of the take-out portion, and a return portion.
It is an injection molding machine equipped with.

According to the present invention, it is possible to obtain the effect of suppressing the reduction of the action of the additive while eliminating the adverse effect of the volatile components generated when the molding material is melted and transported.

It is a figure which shows the injection molding machine which concerns on embodiment of this invention. It is a figure which shows the part of the cylinder of FIG. 1 in detail. It is a figure which shows the structure of the injection apparatus which concerns on the modification of embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an injection molding machine according to an embodiment of the present invention. The injection molding machine 1 of the present embodiment moves an injection device 10 that melts and injects a molding material (resin), a plasticization moving device 20 that conveys the injection device 10, and a mold 43 that is filled with the molding material. It includes a mold clamping device 30, an ejector device 50 that pushes out a solidified molded product from a mold 43, and a control unit 70 that drives and controls each part.

The injection device 10 includes a hopper 12 into which a molding material is charged, a cylinder 13 in which the molding material is melted and conveyed, a screw 14 that rotates and moves forward and backward in the cylinder 13, and a weighing motor that rotationally drives the screw 14. A 16 and an injection motor 17 for driving the screw 14 forward and backward are provided. The cylinder 13 has a nozzle portion 13n at its tip. The hopper 12 is fixed to the cylinder 13. Further, the injection device 10 transmits the power of the bracket 11A that supports the cylinder 13, the frame 11B that supports the weighing motor 16, the frame (not shown) that supports the injection motor 17, and the weighing motor 16 to the screw 14. The timing belt 15 is provided, the timing belt 18 for transmitting the power of the injection motor 17 to the frame 11B, and a screw nut mechanism (ball screw 19a and nut 19b). The frame that supports the injection motor 17 is connected to the bracket 11A that supports the cylinder 13 so that the relative position is fixed. The frame 11B that supports the weighing motor 16 and the bracket 11A that supports the cylinder 13 are movable along the guide 25, and their distances from each other are variably supported. The rear end of the screw 14 is rotatably supported by the frame 11B.

In such a configuration, when the weighing motor 16 is rotationally driven, the rotational motion is transmitted to the screw 14 via the timing belt 15, and the screw 14 rotates. When the injection motor 17 is rotationally driven, the rotational motion is converted into a linear motion via the timing belt 18, the ball screw 19a and the nut 19b, and the frame 11B moves along the guide 25. As a result, the screw 14 advances and retreats in the cylinder 13. Further, the weighing motor 16 and the frame 11B move relative to the bracket 11A following the advance / retreat of the screw 14.

The plasticization moving device 20 includes a plasticizing moving motor 21, a screw nut mechanism (ball screw 22a and nut 22b), and a guide 25 that supports the bracket 11A and the frame 11B of the injection device 10 in a translational manner. The guide 25 and the plasticization moving motor 21 are supported by the molding machine frame 101 via the injection device frame 24. The ball screw 22a is rotatably supported by the injection device frame 24. The nut 22b is connected to the bracket 11A via a spring 23. When the ball screw 22a is rotated by driving the plasticization moving motor 21, the nut 22b and the bracket 11A connected to the nut 22b move in the axial direction of the ball screw 22a. As a result, the bracket 11A moves along the guide 25, and the injection device 10 (cylinder 13, screw 14, frame 11B, weighing motor 16, injection motor 17) moves in the axial direction of the screw 14. By this movement, the nozzle portion 13n of the cylinder 13 can be pressure-welded or separated from the mold 43.

The mold 43 has a movable mold 43a and a fixed mold 43b, and includes a cavity in which a molding material is injected. The nozzle portion 13n of the cylinder 13 is connected to the fixed mold 43b, and a passage 43r for flowing the molding material from the nozzle portion 13n into the cavity is provided.

The ejector device 50 includes an eject pin (not shown) for extruding a molded product and an eject motor 51 for driving the eject pin, and is attached to a movable platen 34. When the eject motor 51 is driven, the eject pin advances into the cavity of the movable mold 43a, and the molded product is pushed out from the movable mold 43a.

The mold clamping device 30 includes a fixed platen 35 that supports the fixed mold 43b, a movable platen 34 that supports the movable mold 43a, a cross head 33, a toggle mechanism 37 that transmits power to the movable platen 34, and mold clamping. Motor 31, a screw nut mechanism (ball screw 32a and nut 32b) that converts the rotational power of the mold clamping motor 31 into translational power and transmits it to the toggle mechanism 37, and a toggle support 38 that supports the toggle mechanism 37 and the ball screw 32a. To be equipped. The movable platen 34 is guided so as to be able to move forward and backward in the opening / closing direction of the mold 43. The toggle support 38 is connected to the fixed platen 35 via a tie rod 36. The nut 32b is fixed to the crosshead 33.

When the mold clamping motor 31 is rotationally driven, this rotational motion is converted into linear motion by the screw nut mechanism (ball screw 32a and nut 32b) and transmitted to the crosshead 33. The direction of linear motion coincides with the opening / closing direction of the mold 43. When the crosshead 33 moves, the toggle mechanism 37 operates and the movable platen 34 moves forward and backward to open and close the mold 43.

The control unit 70 is composed of, for example, a computer, and has a CPU (Central Processing Unit), a storage medium such as a memory, an input interface, and an output interface. The control unit 70 performs various controls by causing the CPU to execute the program stored in the storage medium. Further, the control unit receives a signal from the outside through the input interface and transmits the signal to the outside through the output interface.

<Molding cycle>
The control unit 70 drives and controls each unit to repeatedly perform a weighing process, a mold closing process, a pressure increasing process, a mold clamping process, a filling process, a pressure holding process, a cooling process, a depressurizing process, a mold opening process, a protrusion process, and the like. As a result, the molded product is repeatedly manufactured. A series of operations for obtaining a molded product, basically, an operation from the start of the weighing process to the completion of the ejection process is called a molding cycle. However, if the weighing process is performed during the previous cooling process or during the mold clamping process for the purpose of shortening the molding cycle time, the ejection process is completed from the start of the mold closing process. The operation up to may be called a molding cycle.

The weighing step is a step of sending the molding material to the front portion (nozzle portion 13n side) of the cylinder 13 while melting it by rotating the screw 14. In the weighing step, the screw 14 is retracted as the molding material accumulates in the front portion of the cylinder 13. When the screw 14 retracts to the weighing completion position and a predetermined amount of molding material is accumulated between the tip of the screw 14 and the nozzle portion 13n, the weighing process is completed. The mold closing step is a step of advancing the movable platen 34 and touching the movable mold 43a with the fixed mold 43b. The boosting step is a step of further driving the mold clamping motor 31 to further advance the crosshead 33 from the mold closing completion position to the mold clamping position. A mold clamping force is applied to the mold 43 by the pressurizing step. The mold clamping step is a step of driving the mold clamping motor 31 to maintain the position of the crosshead 33 at the mold clamping position. In the mold clamping step, the mold clamping force generated in the pressurizing step is maintained.

The filling step is a step of advancing the screw 14 at a set moving speed and filling the cavity of the mold 43 with the liquid molding material accumulated in the front portion of the cylinder 13. In the pressure holding step, the injection motor 17 is driven to push the screw 14 forward, and pressure is applied to the molding material remaining in the cylinder 13, so that the pressure of the molding material at the tip of the screw 14 (also referred to as “holding pressure”). This is the process of keeping the set pressure (called). In the pressure holding step, the molding material injected into the cavity of the mold 43 is gradually cooled, and when the pressure holding step is completed, the inlet of the cavity is closed with the solidified molding material. In the cooling step, the molding material in the cavity of the mold 43 is solidified. A weighing step may be performed during the cooling step. The depressurization step is a step of retracting the movable platen 34 by retracting the crosshead 33 from the mold clamping position to the mold opening start position, and reducing the mold clamping force of the mold 43. The mold opening step is a step of retracting the movable platen 34 and separating the movable mold 43a from the fixed mold 43b by retracting the crosshead 33 from the mold opening start position to the mold opening completion position at a set moving speed. .. In the ejection process, the ejector pin is advanced from the standby position to the ejection position at the set movement speed to project the molded product from the movable mold 43a, and then the ejector pin is retracted at the set movement speed to return to the original standby position. It is a process to make it.

A single molding cycle includes, for example, a weighing step, a mold closing step, a pressurizing step, a mold clamping step, a filling step, a pressure holding step, a cooling step, a depressurizing step, a mold opening step, and a protrusion step in this order. The order here is the order of starting each process. The filling, holding and cooling steps are performed during the mold clamping step. The start of the mold clamping step may coincide with the start of the filling step. The end of the decompression process coincides with the start of the mold opening process. In addition, a plurality of steps may be performed at the same time for the purpose of shortening the molding cycle time. For example, the weighing step may be performed during the cooling step of the previous molding cycle or during the mold clamping step. In this case, the mold closing step may be performed at the beginning of the molding cycle. Further, the filling step may be started during the mold closing step.

<Return composition of additives>
Further, as shown in FIG. 2, the injection molding machine 1 of the present embodiment is for inducing the volatile components to the take-out section 71 for taking out the volatile components generated when the molding material is melted in the cylinder 13 and the take-out section 71. It has an injection unit 72a and 72b for injecting the inert gas into the water, and a gas supply unit 73 for supplying the inert gas. Further, the injection molding machine 1 of the present embodiment has a separation unit 75 that separates the additive component from the volatile component taken out from the extraction unit 71, and a second part that returns the separated additive component to the molten molding material. It includes a 1-return unit 76 and a second return unit 77, and a control unit 79 that controls the separated additive components to be returned via the first return unit 76 and the second return unit 77. The control unit 79 may also be used as the control unit 70 that executes the molding process.

In the injection device 10, a solid molding material and a solid or liquid additive are charged from the hopper 12, and the screw 14 rotates in the cylinder 13 to convey these to the nozzle portion 13n side. During transportation, heat is applied from the cylinder 13 to promote melting of the molding material and additives, and for example, a volatile component is generated in a range W1 close to the hopper 12 in the cylinder 13.

One injection portion 72a is provided on the nozzle portion 13n side of the range W1, and the other injection portion 72b is provided on the hopper 12 side of the range W1. An inert gas having a high temperature corresponding to the temperature of the molten molding material is injected from the injection unit 72a, and an inert gas having a lower temperature is injected from the injection unit 72b. The injected inert gas, together with the volatile component of the molding material and the volatile component of the additive, escapes to the hopper 12 side of the cylinder 13 and is sucked from the take-out portion 71. The hopper 12 may be provided with a shutter S, and the shutter may be closed after the molding material is charged so that a large amount of the volatile component released to the hopper 12 side is sucked into the take-out portion 71.

In the cylinder 13, the molten molding material is densely occupied on the nozzle portion 13n side of the injection portions 72a and 72b, and a large amount of the molding material before melting is contained on the hopper 12 side, and a gap is provided between them. .. Therefore, even if the molding material is sent to the nozzle portion 13n side by the rotation of the screw 14, the inert gas can be discharged to the hopper 12 side.

The separation unit 75 separates the components of a specific additive by, for example, utilizing the difference in boiling points of the volatile components and cooling and liquefying the volatile components at a predetermined temperature. In addition, as the separation unit 75, various methods such as a configuration in which the components of the additive are separated by using a column may be adopted.

From the volatile components, the separation unit 75 includes a primary antioxidant, a phosphorus-based secondary antioxidant, a metal inactivating material, a filler, a compatibilizer, a clearing agent, a conductive material, an ultraviolet absorber, and a hindered amine-based light. Separate the components of any one or more of the stabilizers, flame retardants, antifogging agents, antibacterial agents and fungicides.

The first return unit 76 returns the component of the additive separated by the separation unit 75 to the arrangement location of the screw 14 inside the cylinder 13. Specifically, the first return portion 76 is a pipe that leads from the outside of the cylinder 13 to the inner surface of the portion where the screw 14 of the cylinder 13 is arranged. The first return portion 76 may be provided with a valve for preventing the backflow of the molten molding material. The first return portion 76 is arranged closer to the nozzle portion 13n than the inert gas injection portions 72a and 72b.

Of the components separated by the separation unit 75, the components of the additive (for example, an additive having an antioxidant function or a function of reducing thermal decomposition of the molding material) that functions when the molding material is heated are added to the first return unit 76. , And the components of the additive that are required to act on the entire molding material are returned. Specifically, any one or more of a primary antioxidant, a phosphorus-based secondary antioxidant, a metal inactivating material, a filler, a compatibilizer, a clearing agent, and a conductive material.

The second return portion 77 returns the component of the additive separated by the separation portion 75 to the portion on the nozzle portion 13n side of the screw 14 inside the cylinder 13. Specifically, the second return portion 77 is a pipe that leads from the outside of the cylinder 13 to the inner surface of the cylinder 13 on the nozzle portion 13n side in which the molding material before injection is stored by the screw 14. The second return portion 77 may be provided with a valve for preventing the backflow of the molten molding material.

Of the components separated by the separation section 75, the component of the additive that is required to function on the surface portion of the molded product is returned to the second return section 77. Specifically, it is one or more of an ultraviolet absorber, a hindered amine-based light stabilizer, a flame retardant, an antifogging agent, an antibacterial agent and an antifungal agent.

The control unit 79 controls the timing at which the component of the additive is returned via the first return unit 76 and the second return unit 77. These controls may be performed, for example, by driving control of the pump p that pumps the component of the additive to the first return unit 76, or by controlling the opening and closing of the valve. The control unit 79 returns the component of the additive via the first return unit 76 during the measurement of the screw 14, that is, during the period from the start to the completion of the measurement process. By returning the components of the additive through the first return portion 76 during this period, the additive can be well mixed with the molding material. Further, the control unit 79 returns the component of the additive via the second return unit 77 during the period from the start of measurement by the screw to the period before injection of the molding material, that is, from the start of the measurement process to the start of the filling process. Since a relatively high pressure is not applied to the molding material of the second return portion 77 during this period, the component of the additive can be easily returned via the second return portion 77 during this period.

The operation of the screw 14 includes a weighing operation in which the molding material is conveyed from the hopper 12 side to the nozzle portion 13n side by rotating while advancing the melting of the molding material, and a weighing operation in which the molding material is accumulated between the screw 14 and the nozzle portion 13n due to translation. The injection operation of pushing out the molding material from the nozzle portion 13n is included. The operation cycle of the screw 14 continues in the order of weighing (rotation) start, weighing, weighing (rotation) end, standby, injection (translation) start, injection, injection (translation) end, and holding pressure. The weighing may include an operation of translating the screw 14 in the retracting direction. As described above, the control unit 79 controls to return the components of the additive in synchronization with the operation timing of these screws 14.

In addition, instead of the second return section 77, or in combination with the second return section 77, a second return section 78 may be provided to return the component of the additive into the cavity of the mold 43. The type and timing of the component of the additive returned to the second return unit 78 is the same as the type and timing of the component of the additive returned to the second return unit 77.

<Operation explanation>
According to the injection molding machine 1 configured as described above, the molding materials and additives charged into the cylinder 13 from the hopper 12 are melted by being heated in the cylinder 13, and the screw 14 rotates. As a result, it is conveyed to the nozzle portion 13n side. During melting, unnecessary components of the molding material (monomers or by-products during resin synthesis, etc.) and some of the additives volatilize. During the transportation of the molding material, the inert gas is injected from the injection portions 72a and 72b, and the volatile components are sent to the hopper 12 side together with the inert gas, and are sent from the extraction portion 71 to the separation portion 75.

In the separation unit 75, the component of the specific additive is separated from the volatile component, and for example, the component of the liquefied additive is transferred to the first return unit 76 or the second return unit 77 depending on the type of the above-mentioned additive. It is sorted. The control unit 79 synchronizes these with the operation timing of the screw 14 and returns the first return unit 76 and the second return unit 77 to the molten molding material. The component of the additive returned via the first return portion 76 is mixed with the molding material by the screw 14 and sent to the nozzle portion 13n side. The component of the additive returned via the second return portion 77 is subsequently ejected from the nozzle portion 13n along with the molding material, and when the molding material is filled in the cavity of the mold 43, the molding material is charged. It penetrates a lot on the surface.

When the molding material is injected into the mold 43 and then solidified, the mold 43 is opened by the mold clamping device 30, the molded product is removed from the mold 43 by the ejector device 50, and the molded product is conveyed to the carry-out port. To. Then, one cycle of molding processing is completed.

As described above, according to the injection molding machine 1 of the present embodiment, the take-out unit 71 from which the volatile components generated when the molding material is melted is taken out, and the first part where the taken-out components are returned to the melted molding material. A return unit 76 and a second return unit 77 are provided. As a result, the inconvenience that the volatilized component is deteriorated by being exposed to a high temperature for a long time, or a part of the volatilized component is returned to the hopper 12 side and concentrated, and the concentrated component adheres to the molding material is suppressed. can do. Further, the volatilized component includes an additive component, but since these components are returned to the molten molding material again, it is possible to suppress the reduction of the action of the molded product by the additive.

Further, when only the treatment for extracting the volatile component is performed, the volatile additive is removed from the molding material, so that it is necessary to add a large amount of the additive in advance. However, according to the injection molding machine 1 of the present embodiment, the components taken out from the take-out section 71 are returned from the first return section 76 or the second return section 77 again, so that the amount of the additive added is optimized. Can be planned.

Further, according to the injection molding machine 1 of the present embodiment, as a return part for returning the component taken out from the take-out part 71, a first return part 76 leading to a place where the screw 14 is arranged in the cylinder 13 is provided. Then, by returning the component of the additive from the first return portion 76, it becomes possible to mix it well with the molding material. Therefore, when the component of the additive is a component that functions when the molding material is heated, or if it is a component that is required to act on the entire molded product, the function can be fully exerted.

Further, according to the injection molding machine 1 of the present embodiment, when the component is returned from the first return unit 76, the control unit 79 controls so that the component returns during the measurement of the molding material by the screw 14. Therefore, the component returned from the first return portion 76 can be well mixed with the molding material.

Further, according to the injection molding machine 1 of the present embodiment, as a return portion for returning the component taken out from the take-out portion 71, it leads to a portion in the cylinder 13 on the nozzle portion 13n side of the tip of the screw 14 before the injection operation. It has a second return unit 77. Alternatively, it has a second return portion 78 that leads into the cavity of the mold 43. Then, by returning the components of the additive from the second return portions 77 and 78, the additive can be permeated into the surface portion more than the inside of the molded product. Therefore, when the component of the additive is a component that is required to act on the surface portion of the molded product, its function can be fully exerted.

Further, according to the injection molding machine 1 of the present embodiment, the control unit 79 returns the components from the second return units 77 and 78 during the period from the start of weighing the molding material by the screw 14 to before injection. To control. By such synchronous control, the components can be easily returned to the molten molding material when the pressure of the second return portions 77 and 78 is low.

Further, according to the injection molding machine 1 of the present embodiment, a separation unit 75 for separating the additive component from the volatile component taken out from the take-out unit 71 is provided, and the separated additive component is the first return unit. It is sent to 76 and the second return units 77 and 78. With such a configuration, it is possible to prevent unnecessary volatile components from being returned to the molding material and further suppress the occurrence of molding defects, and further, the components of the additive contained in the volatile components can be adjusted according to the type. It is possible to return to a suitable period and a suitable place.

Further, according to the injection molding machine 1 of the present embodiment, from the first return portion 76, as the components of the additive, a primary antioxidant, a phosphorus-based secondary antioxidant, a metal inactivating material, and a filler , One or more of the compatibilizer, the clearing agent and the conductive material are returned. Therefore, since these components are well mixed with the molding material at a high temperature of the molding material, the function of the additive can be fully exerted.

Further, according to the injection molding machine 1 of the present embodiment, from the second return portions 77 and 78, as components of the additive, an ultraviolet absorber, a hindered amine-based light stabilizer, a flame retardant, an antifogging agent, an antibacterial agent and the like. One or more of the fungicides are returned. Therefore, since these components permeate a large amount into the surface portion of the molding material during molding of the molding material, the function of the additive can be fully exerted.

The embodiment of the present invention has been described above. However, the present invention is not limited to the above embodiment. For example, in the above embodiment, the configuration is shown in which the component of the additive is separated from the volatile component taken out and returned, but the volatile component taken out may be returned without performing the separation. Even in this case, it is possible to prevent the volatile component from being exposed to a high temperature for a long time, and to prevent the volatile component from being concentrated and adhering to the molding material. Further, in the above embodiment, the configuration is shown in which the volatile components of the molten molding material are taken out by injecting an inert gas, but the volatile components can be taken out by using various methods such as taking out the volatile components by evacuation. You may take it out. Further, in the above embodiment, the configuration having both the first return unit 76 and the second return units 77 and 78 is shown, but these may be configured to have only one of them. Further, the position of the take-out part and the position of the return part are not limited to the positions shown in the figure, and for example, the return part may be provided on the upstream side of the take-out part.

Further, in the above embodiment, an example in which the present invention is applied to an in-line type injection device in which the molding material is weighed and injected by one cylinder and one screw is shown, but the present invention is shown in FIG. In addition, a plastic cylinder 81 that melts and conveys the molding material and an injection cylinder 85 that injects the melted molding material into the cavity of the mold may be applied to the pre-plastic injection device 80 separately provided. FIG. 3 is a diagram showing a configuration of an injection device according to a modified example of the embodiment. The pre-plastic injection device 80 is, for example, an injection cylinder 81 and a screw 82 capable of rotating and advancing and retreating therein, an injection cylinder 85 and a plunger 86 capable of advancing and retreating therein, and an injection for injecting a molding material into a mold. A nozzle 89 and a switching unit 88 for switching the passage of the molding material are provided. As the screw 82 rotates (the screw 82 may retract while rotating), the molding material is melted and fed along the groove 82a between the fins of the screw 82, and the molding material is sent to the tip of the plastic cylinder 81. It is stored in the part. The switching portion 88 is configured so that the internal flow path portion 88a can be rotationally driven, and the passage between the nozzle portion 81h of the plastic cylinder 81 and the nozzle portion 85h of the injection cylinder 85 at the first rotation angle (angle in FIG. 3). To communicate. When a set amount of molding material is stored in the tip of the plasticizing cylinder 81, the screw 82 advances with the flow path portion 88a at the first rotation angle. As a result, the molten molding material is sent from the plasticizing cylinder 81 to the injection cylinder 85, and the molten molding material is stored at the tip of the injection cylinder 85 (even if the molding material is stored while the plunger 86 is retracted). Good). When the molding material is accumulated at the tip of the injection cylinder 85, the flow path portion 88a is rotationally driven to a second rotation angle (an angle rotated by 90 ° in the direction of the arrow in FIG. 3), whereby the nozzle portion of the injection cylinder 85 The passage between 85h and the injection nozzle 89 communicates with each other. Then, in this state, the plunger 86 of the injection cylinder 85 advances, so that the molding material stored at the tip of the injection cylinder 85 is injected from the injection nozzle 89 into the cavity of the mold. In the case of such a pre-plastic injection device 80, a return portion 91 corresponding to the first return portion 76 of the embodiment may be provided at a position where the screw 82 of the plastic cylinder 81 is arranged. Further, a passage of the return portion 92 leading to the tip portion for storing the molding material of the plastic cylinder 81, the return portion 93 leading to the passage interposed between the plastic cylinder 81 and the switching portion 88, and the passage portion 88a of the switching portion 88. The return portion 94 leading to the injection cylinder 85, the return portion 95 communicating with the tip portion where the molding material is stored in the injection cylinder 85, and the return portion 96 communicating with the passage of the injection nozzle 89 are provided as the return portion corresponding to the second return portion 77 of the embodiment. You may. The return portion 94 is provided so as to communicate with the passage of the molding material both when the flow path portion 88a is rotated to the first rotation angle and when it is rotated to the second rotation angle.

The volatile component (or the component of the additive contained in the volatile component) taken out from the flow path of the molding material from the plasticizing cylinder 81 to the switching section 88 may be returned via the return section, but the switching section 88 may be returned. It is better not to return the volatile component (or the component of the additive contained in the volatile component) taken out from the flow path of the subsequent molding material through the return portion. This is because the volatile components released in the flow path of the molding material after the switching portion 88 are highly likely to be deteriorated by heat. The flow path of the molding material after the switching unit 88 includes the flow path of the molding material from the switching unit 88 to the injection cylinder 85 and the flow path of the molding material from the switching unit 88 to the injection nozzle 89. When the volatile component is taken out from the flow path of the molding material after the switching unit 88, the amount of the additive initially added may be increased by the amount that the volatile component is not returned to the molding material. According to such a configuration, it is possible to remove the volatile component deteriorated by heat by taking out the volatile component, and in addition, by increasing the initial amount of the additive input, the shortage of the additive is compensated. be able to. The amount of the additive initially charged from the hopper 12 may be determined in consideration of the balance between the removal of the volatile component in the middle and the return of the component of the additive. In addition, the details shown in the embodiments can be appropriately changed without departing from the spirit of the invention.

1 Injection molding machine 10 Injection device 12 Hopper 13 Cylinder 13n Nozzle part 14 Screw 43 Mold 71 Extraction part 72a, 72b Injection part 73 Gas supply part 75 Separation part 76 First return part 77, 78 Second return part 79 Control part

Claims (6)

An injection device that melts and injects molding material,
A take-out part that takes out the components volatilized when the molding material is melted, and
A return portion that returns the component taken out from the take-out portion to the molten molding material from a position different from that of the take-out portion, and a return portion.
An injection molding machine equipped with. The injection device has a cylinder, a screw, and a nozzle portion for injecting a molding material.
The return portion leads to at least one of the placement location of the screw in the cylinder, the nozzle portion side of the screw in the cylinder, and the cavity of the mold.
The injection molding machine according to claim 1. A control unit that controls the return of the component from the return unit is further provided.
The control unit
The component is returned from the return portion from the start of weighing by the screw to before the injection of the molding material.
The injection molding machine according to claim 2. Further provided with a separation unit for separating a specific component from the extracted component,
The separated component is sent from the separation part to the return part.
The injection molding machine according to any one of claims 1 to 3. Further provided with a separation unit for separating a specific component from the extracted component,
One or more of the primary antioxidant, the phosphorus-based secondary antioxidant, the metal inactivating material, the filler, the compatibilizer, the clearing agent and the conductive material separated by the separation part. The injection molding machine according to claim 2 or 3, which is returned from a portion of the cylinder on the nozzle portion side of the screw or from the return portion leading to the cavity. Further provided with a separation unit for separating a specific component from the extracted component,
One or more of an ultraviolet absorber, a hindered amine-based light stabilizer, a flame retardant, an antifogging agent, an antibacterial agent and an antifungal agent separated by the separation portion are placed at the location of the screw in the cylinder. The injection molding machine according to claim 2 or 3, which is returned from the return portion.

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