KR102294128B1 - Method and machine for pre-processing of molding material, injection molding machine, and injection molding method - Google Patents

Abstract

Provided are a molding material pretreatment method, a pretreatment apparatus, an injection molding machine, and an injection molding method that can increase the content of an inert gas in the molding material and further suppress oxidation of the molding material during molding.
After drying the molding material by heating, in the container 40 filled with an inert gas, the temperature of the molding material is lowered. At that time, the temperature of the molding material is lowered while maintaining the pressure in the container 40 substantially constant. Further, in the container 40, the temperature of the molding material is lowered more gently than natural cooling. Thereafter, the molding material whose temperature has decreased is supplied to the molding machine 2 . In this way, the content of the inert gas in the molding material can be increased. Therefore, oxidation of the molding material at the time of molding can be suppressed.

Description

Pre-processing method of molding material, pre-processing apparatus, injection molding machine, and injection molding method

This application claims priority on the basis of Japanese Patent Application No. 2014-136312, filed on July 1, 2014, and Japanese Patent Application No. 2015-109397, filed on May 29, 2015. The entire contents of the application are incorporated herein by reference.

The present invention relates to a pre-processing method and a pre-processing apparatus for a molding material supplied to a molding machine, and an injection molding machine and an injection molding method for melting the pre-treated molding material and injecting it into a mold.

Conventionally, in the manufacturing process of a resin product, pre-processing, such as drying, is performed with respect to the molding material, such as resin pellet, supplied to an injection molding machine. About the pre-processing of a molding material, it describes in patent document 1, for example. In the apparatus of Patent Document 1, a resin material in the form of chips or pellets is supplied to a plasticizing apparatus of an injection molding machine through a dehumidifying dryer, an inert gas permeation apparatus, and a material hopper (see Fig. 1).

Japanese Patent Laid-Open No. 2001-353750 Japanese Patent Laid-Open No. 10-87752

However, when the molding material supplied to the injection molding machine is oxidized, discoloration such as yellowing occurs in the resin product after molding. For this reason, in the conventional pre-processing apparatus, the oxidation of the molding material was suppressed by supplying nitrogen gas which is an inert gas to the inside of the hopper which stores a molding material.

Further, Patent Document 2 describes storing the resin pellets in an inert gas atmosphere to reduce the amount of oxygen contained in the resin pellets. In this way, if the oxygen content in the molding material is reduced and an inert gas is contained in the molding material instead, the molding material is supplied to the injection molding machine and then melted and injected in the injection molding machine during the molding process. Oxidation of materials can be suppressed.

However, in recent years, in resin products used for optical parts, etc., the required quality has become higher, and a technique capable of further suppressing discoloration due to oxidation is demanded.

The present invention has been made in view of such circumstances, and includes a method for pretreatment of a molding material, a pretreatment apparatus, which can increase the content of an inert gas in the molding material and further suppress oxidation of the molding material during molding; An object of the present invention is to provide an injection molding machine and an injection molding method.

The first invention of the present application is a method for pre-processing a molding material supplied to a molding machine, a) drying the molding material by heating, b) after the step a), in a container filled with an inert gas, A step of lowering the temperature of the material, c) a step of supplying a molding material to the molding machine after the step b), in the step b), while maintaining the pressure in the container substantially constant lowers the

The second invention of the present application is a pretreatment method for a molding material of the first invention, wherein in the step b), the temperature of the molding material is lowered more gently than natural cooling.

The third invention of the present application is a pretreatment method of a molding material supplied to a molding machine, a) a step of drying the molding material by heating, b) after the step a), in a container filled with an inert gas, A step of lowering the temperature of the material; c) a step of supplying a molding material to the molding machine after the step b). In the step b), the temperature of the molding material is lowered more gently than natural cooling.

The fourth invention of the present application is a pretreatment method for a molding material according to the second or third invention, wherein in the step b), the temperature drop per unit time of the molding material increases with the passage of time.

A fifth invention of the present application is a method for pre-treating a molding material according to the second or third invention, wherein, in the step b), the temperature of the molding material is lowered in stages.

A sixth invention of the present application is a pretreatment method for a molding material according to any one of the first to fifth inventions, wherein in the step b), the temperature of the molding material is lowered to 60° C. or less.

A seventh invention of the present application is a pretreatment method for the molding material according to any one of the first to sixth inventions, wherein the pressure inside the container in the step b) is higher than the environmental pressure outside the container.

An eighth invention of the present application is a pretreatment method for a molding material according to the seventh invention, wherein the pressure in the container in the step b) is lower than the injection pressure of the molding material in the molding machine.

A ninth invention of the present application is a pretreatment method for a molding material according to the eighth invention, wherein the pressure in the container in the step b) is less than 1 MPa.

The tenth invention of the present application is a pretreatment method of the molding material according to any one of the first to ninth inventions, after the step b) and before the step c), adding a step of maintaining a constant temperature of the molding material have as

The eleventh invention of the present application is a method for pre-processing a molding material according to any one of the first to tenth inventions, d) measuring the temperature in the vicinity of the supply port to the molding machine, and based on the measured temperature, It further has the process of controlling the temperature of the molding material in before the injection nozzle in a molding machine.

The twelfth invention of the present application is a pre-processing method of the molding material according to any one of the first to eleventh inventions, wherein the molding material for optical parts is treated as an object.

A thirteenth invention of the present application is an apparatus for pre-processing a molding material supplied to a molding machine, comprising: a cooling vessel for accommodating the molding material dried by heating therein; a gas supply unit for filling the inside of the cooling vessel with an inert gas; and a cooling mechanism for lowering the temperature of the molding material accommodated in the cooling vessel, and by supplying the inert gas from the gas supply unit, the pressure in the cooling vessel is maintained substantially constant while the cooling mechanism is configured to reduce the temperature of the molding material. lowers the

A fourteenth invention of the present application is a pretreatment method for a molding material according to the thirteenth invention, wherein the cooling mechanism lowers the temperature of the molding material more gently than natural cooling.

A fifteenth invention of the present application is an apparatus for pre-processing a molding material supplied to a molding machine, comprising: a cooling vessel for storing the molding material dried by heating therein; a gas supply unit for filling the inside of the cooling vessel with an inert gas; and a cooling mechanism for lowering the temperature of the molding material stored in the cooling vessel, wherein the cooling mechanism lowers the temperature of the molding material more gently than natural cooling.

A sixteenth invention of the present application is an apparatus for pre-processing a molding material according to any one of the thirteenth to fifteenth inventions, comprising: a heating vessel for storing the molding material therein on an upstream side of a conveyance path rather than the cooling vessel; A heating and drying mechanism for drying the molding material stored in the heating vessel by heating, and a conveying pipe for conveying the molding material from the heating vessel to the cooling vessel are further provided.

The seventeenth invention of the present application is a preprocessing apparatus for a molding material according to any one of the thirteenth to sixteenth inventions. , further having a vent in communication with the outside, wherein the pressure in the cooling vessel or the other vessel located on the downstream side of the cooling vessel is higher than the external environmental pressure.

An eighteenth invention of the present application is a pre-processing apparatus for a molding material according to any one of the 13th to 17th inventions, further comprising a temperature control mechanism for maintaining a constant temperature of the molding material after being cooled by the cooling mechanism have

A nineteenth invention of the present application is a pre-processing apparatus for a molding material according to any one of the thirteenth to eighteenth inventions, wherein the molding material for optical parts is an object to be processed.

The twentieth invention of the present application is an injection molding machine that melts a molding material and injects it into a mold, comprising: a cylinder; a supply port for supplying a pre-processed molding material to the cylinder; An injection nozzle for injecting the molten molding material from the cylinder, and a screw for conveying the molding material to the injection nozzle in the cylinder, the supply port is inert in a container containing the molding material dried by heating By supplying the gas, a molding material whose temperature is lowered while maintaining the pressure in the container approximately constant is supplied.

A twenty-first invention of the present application is the injection molding machine of the twentieth invention, wherein a molding material whose temperature is lowered more gently than natural cooling in the container is supplied to the supply port.

The twenty-second invention of the present application is an injection molding machine that melts a molding material and injects it into a mold, comprising: a cylinder; a supply port for supplying a pre-processed molding material to the cylinder; An injection nozzle for injecting the molten molding material from the cylinder, and a screw for conveying the molding material to the injection nozzle side in the cylinder, and an inert gas containing the molding material dried by heating at the supply port In the filled container, a molding material whose temperature is lowered more gently than natural cooling is supplied.

The twenty-third invention of the present application is the injection molding machine according to any one of the twentieth to twenty-second inventions, wherein the supply port is supplied with a molding material maintained at a constant temperature after the temperature in the container is lowered.

A twenty-fourth invention of the present application is the injection molding machine according to any one of the twentieth to twenty-third inventions, wherein the temperature of the molding material in front of the injection nozzle in the cylinder is controlled based on the temperature in the vicinity of the supply port. .

The twenty-fifth invention of the present application is an injection molding method in which a molding material is melted and injected into a mold, x) a step of supplying a pre-treated molding material to a cylinder through a supply port, and y) a molding material in the cylinder. a step of melting; z) a step of injecting the molten molding material from the injection nozzle of the cylinder; While maintaining the pressure in the container substantially constant, the molding material whose temperature has been lowered is supplied to the cylinder through the supply port.

A twenty-sixth invention of the present application is the injection molding method of the twenty-fifth invention, wherein in the step x), a molding material whose temperature is lowered more gently than natural cooling in the container is supplied to the cylinder through the supply port. .

The twenty-seventh invention of the present application is an injection molding method in which a molding material is melted and injected into a mold, x) a step of supplying a pre-treated molding material to a cylinder through a supply port, and y) a molding material in the cylinder. a step of melting; z) a step of injecting the molten molding material from the injection nozzle of the cylinder; The molding material lowered more gently than natural cooling is supplied to the cylinder through the supply port.

A twenty-eighth invention of the present application is the injection molding method according to any one of the twenty-fifth to twenty-seventh inventions, wherein in the step x), the molding material maintained at a constant temperature after the temperature in the container is lowered is supplied through the supply port. is supplied to the cylinder through

A twenty-ninth invention of the present application is the injection molding method according to any one of the twenty-fifth to twenty-eighth inventions, wherein in the step y), based on the temperature in the vicinity of the supply port, the injection molding is performed in front of the injection nozzle in the cylinder. Controls the temperature of the molding material.

According to the 1st - 29th invention of this application, content of the inert gas in a molding material can be increased. As a result, oxidation of the molding material at the time of molding can be suppressed.

In particular, according to the 4th invention and 5th invention of this application, in the process b), a high temperature period can be taken long. Thereby, the temperature of a molding material can be reduced, fully containing an inert gas in a molding material.

In particular, according to the 6th invention and 7th invention of this application, content of the inert gas in a molding material can be increased more.

In particular, according to the tenth invention, the eighteenth invention, the twenty-third invention, and the twenty-eighth invention of the present application, the temperature of the molding material supplied to the molding machine can be more stable. As a result, the resin product can be molded stably.

In particular, according to the eleventh, twenty-fourth, and twenty-ninth inventions of the present application, the position at which the molding material melts in front of the injection nozzle can be adjusted. Thereby, for example, the molding material is melted just before the injection nozzle, and the period of high temperature can be shortened. As a result, oxidation of a molding material can be suppressed more.

In particular, according to the seventeenth invention of the present application, it is possible to suppress backflow of gas from the molding machine into the cooling vessel or another vessel located on the downstream side of the cooling vessel. Thereby, it can suppress that the temperature of a molding material rises before supply to a molding machine.

1 is a view showing the configuration of a pre-processing apparatus and an injection molding machine.
2 is a view showing the configuration of the injection molding machine.
3 is a block diagram showing the configuration of a control system of a pre-processing apparatus and an injection molding machine.
4 is a flowchart showing an example of preprocessing.
5 is a graph showing an example of the temperature change of the resin pellets in the cooling hopper.
6 is a graph showing an example of the temperature change of the resin pellets in the cooling hopper.
7 is a graph showing an example of the temperature change of the resin pellets in the cooling hopper.
8 is a graph showing an example of the temperature change of the resin pellets in the cooling hopper.
It is a figure which shows the structure of the vicinity of the vapor phase hopper which concerns on a modified example.
10 is a diagram showing the configuration of a pre-processing apparatus and an injection molding machine according to a modified example.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described, referring drawings.

<1. About device configuration>

1 is a diagram showing the configuration of a pre-processing apparatus 1 and an injection molding machine 2 according to an embodiment of the present invention. The pretreatment device 1 performs pretreatment such as drying on resin pellets, which are powder or three-dimensional molding materials, and supplies the treated resin pellets to the injection molding machine 2 . The injection molding machine 2 melts the resin pellets supplied from the pretreatment device 1 and injects them into the mold 209 , and solidifies the resin in the mold 209 to mold the resin product. However, in Fig. 1, the configuration of the injection molding machine 2 is schematically shown. The pretreatment device 1 and the injection molding machine 2 are connected as shown in FIG. 1 to constitute a single resin product manufacturing system 100 .

The pre-processing apparatus 1 of this embodiment makes resin pellets for optical components a process object. The resin pellets supplied from the pretreatment device 1 are molded in the injection molding machine 2 to become transparent optical parts such as a light guide plate. In the molding of transparent optical parts, prevention of discoloration due to oxidation is a particularly important quality control item. However, in the present invention, the resin pellets to be treated are not necessarily limited to the resin pellets for optical parts.

As shown in FIG. 1 , the pre-processing apparatus 1 of the present embodiment includes a head hopper 10 , a heating hopper 20 , a heating and drying mechanism 30 , a cooling hopper 40 , a cooling mechanism 50 , A gas phase hopper 60 and a control unit 70 are provided.

The head hopper 10 is a container for storing the resin pellets before drying therein. The head hopper (10) has a bottomed cylindrical hopper body (11) having an opening (13) thereon, and a cover part (12) mounted on the top of the hopper body (11). Inside the hopper body 11, a space for storing the resin pellets is provided. The lid part 12 closes the opening 13 of the upper part of the hopper body 11 . In addition, when the cover part 12 is removed, the upper part of the hopper body 11 is opened, and resin pellets can be put into the inside of the hopper body 11 through the opening 13 .

The heating hopper 20 is a container (heating container) for storing resin pellets therein on the downstream side of the conveying path than the lead hopper 10, and on the upstream side of the conveying path from the cooling hopper 40. As shown in Fig. 1, the heating hopper 20 has a substantially cylindrical side wall 21, a funnel-shaped bottom 22 that gradually converges from the lower end of the side wall 21 downward, and a heating hopper It has a top plate part 23 which covers the upper part of (20). Inside the heating hopper 20, there is provided a space for storing and drying the resin pellets.

A first transfer hopper 24 smaller than the heating hopper 20 is provided on the upper portion of the heating hopper 20 . The first transfer hopper 24 is a container for temporarily accommodating the resin pellets when supplying the resin pellets to the heating hopper 20 . The head hopper 10 and the first transfer hopper 24 are connected to each other through the first transfer pipe 81 . In addition, at the lower end of the first transfer hopper 24, an opening and closing inlet 241 is provided. When the inlet 241 is opened, the resin pellets stored in the first transfer hopper 24 are put into the heating hopper 20 .

The heat drying mechanism 30 is a mechanism for drying the resin pellets stored in the heating hopper 20 by heating. The heating and drying mechanism (30) has a gas heating tube (31) that circulates while heating the gas. One end of the gas heating tube (31) is connected to a suction port (25) provided on the side wall (21) of the heating hopper (20). The other end of the gas heating tube (31) is connected to a jet port (26) disposed inside the heating hopper (20). Moreover, in the middle of the path|route of the gas heating tube 31, the blower 32 and the heat exchanger 33 are provided.

When the blower 32 is operated, as indicated by an arrow A1 in FIG. 1 , an airflow from the suction port 25 to the jet port 26 is generated in the gas heating tube 31 . The gas sucked in from the heating hopper 20 to the gas heating tube 31 is heated in the heat exchanger 33 to become hot air. Then, the hot air is blown out from the jet port 26 to the inside of the heating hopper 20 . However, in the middle of the path of the gas heating tube 31, an adsorber for adsorbing moisture contained in the gas may be additionally provided.

The hot air blown out from the jet port 26 passes through the gap between the resin pellets stored in the heating hopper 20 and is diffused in the heating hopper 20 . Thereby, the resin pellets are heated, moisture evaporates from the resin pellets, and the resin pellets are dried. That is, the gas diffused in the heating hopper 20 absorbs moisture from the resin pellets. Further, the absorbed gas passes through the suction port 25 from the heating hopper 20 and is again sucked into the gas heating tube 31 .

The cooling hopper 40 is a container (cooling container) for storing resin pellets in the downstream side of the conveying path than the heating hopper 20, and on the upstream side of the conveying path than the gaseous-phase hopper 60. As shown in Fig. 1, the cooling hopper 40 has a substantially cylindrical side wall 41, a funnel-shaped bottom portion 42 that gradually converges from the lower end of the side wall 41 downward, and a cooling hopper It has a top plate part 43 which covers the upper part of (40). Inside the cooling hopper 40, there is provided a space for storing the resin pellets to lower the temperature.

A second transfer hopper 44 smaller than the cooling hopper 40 is installed on the upper portion of the cooling hopper 40 . The second transfer hopper 44 is a container for temporarily accommodating the resin pellets when supplying the resin pellets to the cooling hopper 40 . The heating hopper 20 and the second conveying hopper 44 are connected to each other through the second conveying pipe 82 . In addition, at the lower end of the second transfer hopper 44, an opening and closing inlet 441 is provided. When the inlet 441 is opened, the resin pellets stored in the second transfer hopper 44 are put into the cooling hopper 40 .

The cooling mechanism 50 is a mechanism for lowering the temperature of the resin pellets stored in the cooling hopper 40 . The cooling mechanism (50) has a gas cooling tube (51) that circulates the gas while cooling it. One end of the gas cooling tube (51) is connected to a suction port (45) provided on the side wall (41) of the cooling hopper (40). The other end of the gas cooling tube (51) is connected to a jet port (46) provided inside the cooling hopper (40). In addition, a blower 52 and a heat exchanger 53 are provided in the middle of the path of the gas cooling tube 51 .

When the blower 52 is operated, as indicated by an arrow A2 in FIG. 1 , an airflow from the suction port 45 to the jet port 46 is generated in the gas cooling tube 51 . The gas sucked from the cooling hopper 40 into the gas cooling tube 51 passes through the heat exchanger 53 to lose heat to the refrigerant in the heat exchanger 53 . Thereby, the temperature of gas falls. Then, the cooled gas is ejected from the ejection port 46 into the cooling hopper 40 .

The gas ejected from the jet port 46 passes through the gap between the resin pellets stored in the cooling hopper 40 and diffuses into the cooling hopper 40 . Thereby, the temperature of the resin pellet falls. Further, the gas whose temperature has increased due to contact with the resin pellets passes through the suction port 45 from the cooling hopper 40 and is again sucked into the gas cooling tube 51 .

However, the temperature of the refrigerant in the heat exchanger 53 can be set to an arbitrary temperature based on a command from the control unit 70 . When the temperature of the refrigerant is adjusted, the cooling rate of the resin pellets by the cooling mechanism 50 can be adjusted.

The vapor phase hopper 60 is located on the downstream side of the conveyance path rather than the cooling hopper 40 and is installed in the upper part of the injection molding machine 2 . Inside the gas phase hopper 60, a space for storing the resin pellets after cooling is provided. The cooling hopper 40 and the gas phase hopper 60 are connected to each other through the third conveyance pipe 83 . Further, the gas phase hopper 60 and the injection molding machine 2 are connected to each other through a supply pipe 61 . The supply pipe 61 is provided with an on/off valve 62 . When the opening/closing valve 62 is opened, the resin pellets stored in the gas phase hopper 60 pass through the supply pipe 61 and are supplied to the cylinder 211 of the injection molding machine 2 .

In addition, the supply pipe 61 is provided with a vent port 63 and a temperature sensor 64 . The vent port 63 communicates with the outside of the supply pipe 61 via a check valve 631 . The check valve 631 permits only the passage of gas from the inside of the supply pipe 61 to the outside. Accordingly, when the internal pressure of the supply pipe 61 is higher than the external pressure, the gas is discharged from the inside of the supply pipe 61 to the outside. Further, the temperature sensor 64 measures the temperature of the gas in the supply pipe 61 in the vicinity of the supply port of the injection molding machine 2 . The measurement result of the temperature sensor 64 is transmitted to the control unit 70 .

A first suction pipe 84 , a second suction pipe 85 , and a third suction pipe 86 are connected to the upper portions of the first conveying hopper 24 , the second conveying hopper 44 , and the gas phase hopper 60 , respectively. has been The other ends of the first suction pipe 84 , the second suction pipe 85 , and the third suction pipe 86 are connected to one merging pipe 87 . Further, the other end of the merging pipe 87 is connected to the first conveying pipe 81 . In addition, a blower 88 is provided in the middle of the path of the merging pipe 87 .

When the blower 88 is operated, as indicated by the arrow A3 in FIG. 1 , the first suction pipe 84 , the second suction pipe 85 , the third suction pipe 86 , and the merging pipe 87 are inside the , from the first transport hopper 24 , the second transport hopper 44 , and the gas phase hopper 60 , an airflow is generated through the blower 88 toward the first transport pipe 81 . Then, as indicated by arrows A4, A5, and A6 in FIG. 1, the airflow from the top hopper 10 through the first conveying pipe 81 to the first conveying hopper 24, the heating hopper 20 An air flow from the second conveying pipe 82 to the second conveying hopper 44 and from the cooling hopper 40 passing through the third conveying pipe 83 to the gaseous hopper 60 are generated. . By these airflows, the resin pellets are conveyed by air force.

However, the connection part of the first transport hopper 24 and the first suction pipe 84, the connection part between the second transport hopper 44 and the second suction pipe 85, and the gas phase hopper 60 and the third suction pipe 86 Each of the connecting portions is provided with a punched metal plate (not shown). The punched metal plate is provided with a plurality of through holes smaller than the respective resin pellets. Thereby, the resin pellets are prevented from flowing into each of the suction pipes 84, 85, 86 while allowing the gas to pass through.

In addition, the pre-processing apparatus 1 has a plurality of nitrogen gas supply units 89 for supplying nitrogen gas, which is an inert gas, into the piping in the apparatus and the inside of the hopper. As shown in Fig. 1, in this embodiment, the head hopper 10, the heating hopper 20, the gas heating tube 31, the cooling hopper 40, the gas cooling tube 51, the supply pipe 61, the first A nitrogen gas supply unit 89 is connected to the first conveying pipe 81 , the second conveying pipe 82 , the third conveying pipe 83 , and the merging pipe 87 , respectively.

The nitrogen gas supply unit 89 supplies dry nitrogen gas at a positive pressure rather than an external pressure to each of the above-mentioned units. For this reason, when the plurality of nitrogen gas supply units 89 are operated, the resin pellet transport path in the pretreatment device 1 (from the first hopper 10, the first transport pipe 81, the first transport hopper 24) , to the supply pipe 61 through the heating hopper 20, the second conveying pipe 82, the second conveying hopper 44, the cooling hopper 40, the third conveying pipe 83, and the gas phase hopper 60. all the way), it is filled with nitrogen gas. Moreover, the conveyance path|route of the resin pellet in the pretreatment apparatus 1 becomes a positive pressure rather than an external environmental pressure. Thereby, the intrusion of external air into the conveyance path is suppressed. As a result, oxidation of the resin pellets in the pretreatment device 1 is suppressed.

However, the position or number of the nitrogen gas supply units 89 is not limited to the example of FIG. 1 .

FIG. 2 is a diagram showing the configuration of the injection molding machine 2 in more detail than FIG. 1 . The injection molding machine 2 fills the cavity space 293 in the mold device 290 with a liquid resin and solidifies the filled resin to mold a resin product. As shown in Fig. 2, the injection molding machine 2 includes an injection device 210 for filling the mold device 290 with a liquid resin, and a mold for closing, clamping, and opening the mold device 290. A fastening device 220 is provided. The mold apparatus 290 has a stationary mold 291 and a movable mold 292 . A cavity space 293 corresponding to the shape of the resin product is formed between the stationary mold 291 and the movable mold 292 .

The injection device 210 includes a cylinder 211 which is a horizontally extending cylindrical container, and a screw 212 horizontally arranged in the cylinder 211 . A supply port 213 is provided on the rear upper surface of the cylinder 211 . In the pretreatment device (1), the pretreated resin pellets are supplied to the inside of the cylinder (211) through the supply port (213). Meanwhile, an injection nozzle 214 is provided at the front end of the cylinder 211 . In addition, a heater 215 serving as a heating source is provided on the outer periphery of the cylinder 211 .

The screw 212 is rotatable in the cylinder 211 and is arrange|positioned so that advancing and retreating is possible. The injection device 210 includes a metering motor 216 for rotating the screw 212 and an injection motor 217 for moving the screw 212 forward and backward. When the metering motor 216 is driven to rotate the screw 212 , the resin pellets are conveyed forward (the injection nozzle 214 side) along the spiral groove of the screw 212 . The resin pellets are gradually melted by the heat from the heater 215 while being conveyed forward. As a result, the resin pellets become liquid resins. Further, as the liquid resin is sent to the front of the screw 212 and accumulated near the front end of the cylinder 211 , the screw 212 retreats and moves away from the injection nozzle 214 .

In this state, when the injection motor 217 is driven and the screw 212 is advanced, the liquid resin accumulated in the front of the screw 212 passes through the injection nozzle 214 into the cavity space ( 293) is charged. After that, the injection motor 217 is further driven, and the screw 212 is further advanced. As a result, a pressure is applied to the resin in the cavity space 293, and the insufficient amount of the resin due to the shrinkage is replenished.

The mold clamping device 220 includes a fixed platen 221 on which the fixed mold 291 is mounted, a movable platen 222 on which the movable mold 292 is mounted, and a toggle for moving the movable platen 222 . A mechanism 223 is provided. By advancing and retreating the movable platen 222 with respect to the fixed platen 221 along the tie bar 224, mold closing, clamping, and mold opening are performed. In addition, the mold clamping device 220 includes a mold clamping motor 225 for moving the movable platen 222, an ejector motor 226 for moving an ejector pin mounted on the movable platen 222 forward and backward; It has a mold thickness motor 227 for moving the movable platen 222 and the toggle mechanism 223 according to the thickness of the mold device 290 .

By driving the mold clamping motor 225 to advance the movable platen 222, the mold device 290 is closed. After completion of mold closing, a clamping force obtained by multiplying the driving force by the clamping motor 225 by a toggle magnification is generated, and clamping is performed by the clamping force. By the clamping, a cavity space 293 is formed between the movable mold 292 and the stationary mold 291 . The liquid resin filled in the cavity space 293 from the injection device 210 solidifies in the cavity space 293 to become a resin product. Thereafter, the mold opening of the mold apparatus 290 is performed by driving the mold clamping motor 225 to retract the movable platen 222 . Further, the resin product is taken out from the movable mold 292 by driving the ejector motor 226 .

3 is a block diagram showing the configuration of the control system of the preprocessing apparatus 1 and the injection molding machine 2 . The pre-processing apparatus 1 and the injection molding machine 2 are provided with control parts 70 and 230 for controlling the operation of each part, respectively. As shown in FIG. 3 , the control unit 70 of the pretreatment device 1 includes the blower 32 , the heat exchanger 33 , the blower 52 , the heat exchanger 53 , and the on/off valve 62 . , the temperature sensor 64 , the blower 88 , and the plurality of nitrogen gas supply units 89 are electrically connected to each other. The control unit 230 of the injection molding machine 2 is electrically connected to a plurality of motors 216 , 217 , 225 , 226 , 227 and a heater 215 in the injection molding machine 2 , respectively.

These control units 70 and 230 are constituted by, for example, a computer or a microcomputer having an arithmetic processing unit such as a CPU or a memory. The control units 70 and 230 operate and control the respective units based on a preset program or an input signal from the outside. Thereby, the pre-treatment and injection molding treatment of the resin pellets proceed.

However, some of the plurality of control objects described above may be separated from the control units 70 and 230 and operated manually.

1 and 3 , the control unit 70 of the preprocessing apparatus 1 and the control unit 230 of the injection molding machine 2 are connected to each other so as to be able to communicate with each other. Accordingly, request signals and necessary data can be exchanged with each other between the control units 70 and 230 . Thereby, for example, the timing of the operation of the pre-processing apparatus 1 and the timing of the operation of the injection molding machine 2 can be mutually adjusted so that stagnation or shortage of the resin pellets does not occur. In addition, as described later, in the present embodiment, the control unit 70 of the preprocessor 1 transmits the measurement result acquired from the temperature sensor 64 to the control unit 230 of the injection molding machine 2 . Then, the control unit 230 of the injection molding machine 2 adjusts the output of the heater 215 based on the received measurement result.

<2. About the flow of processing>

Next, the flow of the pre-processing of resin pellets and the injection molding process in the above-mentioned resin product manufacturing system 100 is demonstrated. 4 is a flowchart showing an example of processing in the resin product manufacturing system 100 .

In this resin product manufacturing system 100, when manufacturing a resin product, first, supply of nitrogen gas from the plurality of nitrogen gas supply units 89 of the pretreatment device 1 is started. Thereby, nitrogen gas is filled in the whole conveyance path|route of the resin pellet in the pre-processing apparatus 1 (step S1). Next, the cover part 12 of the head hopper 10 is removed, and the resin pellets are put into the hopper body 11 through the opening 13 of the hopper body 11 (step S2). When the injection of the resin pellets is completed, the lid part 12 is placed again, and the opening 13 of the hopper body 11 is closed.

Next, the blower 88 is operated to generate an airflow of nitrogen gas in the first conveyance pipe 81 , the second conveyance pipe 82 , and the third conveyance pipe 83 . The resin pellets discharged from the lower part of the head hopper 10 pass through the first conveying pipe 81 and are conveyed by energy to the first conveying hopper 24 . In addition, the resin pellets stored in the first transfer hopper 24 are put into the heating hopper 20 by opening the inlet 241 (step S3).

The resin pellets put into the heating hopper 20 are heat-dried by the heating and drying mechanism 30 (step S4). Specifically, by operating the blower 32 and the heat exchanger 33 , the hot air of nitrogen gas is supplied to the inside of the heating hopper 20 from the jet port 26 . As a result, the resin pellets are heated, moisture evaporates from the resin pellets, and the moisture content of the resin pellets decreases.

The heat-dried resin pellets are discharged from the lower part of the heating hopper 20 , pass through the second conveying pipe 82 , and are conveyed by energy to the second conveying hopper 44 . In addition, the resin pellets stored in the second transfer hopper 44 are introduced into the cooling hopper 40 by opening the inlet 441 (step S5).

The resin pellets put into the cooling hopper 40 are cooled by the cooling mechanism 50 (step S6). Specifically, by operating the blower 52 and the heat exchanger 53 , the low-temperature nitrogen gas is supplied into the cooling hopper 40 from the jet port 46 . Thereby, the temperature of the resin pellet falls.

As described above, the conveyance path of the resin pellets in the pretreatment device 1 is filled with nitrogen gas. For this reason, in the pretreatment device 1, the oxygen content in the resin pellets gradually decreases, and instead, the nitrogen gas content in the resin pellets gradually increases. In particular, the saturated content of nitrogen gas in the resin pellets increases as the temperature of the resin pellets decreases. For this reason, when the temperature of the resin pellet in the cooling hopper 40 is reduced, the nitrogen gas content in the resin pellet can be increased more. As a result, it is possible to suppress the occurrence of discoloration due to oxidation during injection molding, which will be described later.

However, the saturated content of nitrogen gas in the resin pellets decreases as the ambient pressure decreases. Therefore, if the pressure in the cooling hopper 40 is also reduced along with the temperature, the saturated content of nitrogen gas in the resin pellets cannot be sufficiently increased. For this reason, in this pre-processing apparatus 1, the temperature of the resin pellets is reduced while maintaining the pressure in the cooling hopper 40 substantially constant by continuing the supply of nitrogen gas from the nitrogen gas supply part 89. Thereby, a larger amount of nitrogen gas can be contained in the resin pellet.

In addition, in step S6, the pressure in the cooling hopper 40 is made into a positive pressure rather than the external environmental pressure. Thereby, the content of nitrogen gas in the resin pellets becomes higher. However, in order to prevent bubbles from being generated due to reduced pressure during injection molding, it is preferable that the pressure in the cooling hopper 40 is lower than the injection pressure of the resin in the injection molding machine 2 . Moreover, since the pressure in the cooling hopper 40 does not restrict the freedom degree of device design, it is preferable to set it as less than 1 MPa which becomes the object of a high-pressure gas security method. Specifically, the pressure in the cooling hopper 40 in step S6 may be set to a pressure slightly higher than the environmental pressure.

5 is a graph showing an example of a temperature change of the resin pellets in the cooling hopper 40 . The horizontal axis in FIG. 5 represents the time after the start of cooling. The vertical axis of Fig. 5 represents the temperature of the resin pellets. 5, the temperature change of the resin pellets in this embodiment is indicated by a solid line, and as a comparative example, the temperature change of the resin pellets when the resin pellets are naturally cooled by the environmental temperature is indicated by a dashed-dotted line. .

In FIG. 5, the temperature Tb before cooling is the temperature after heat-drying of the resin pellet used as a process object, and becomes 100-150 degreeC, for example. On the other hand, the temperature Ta after cooling is a temperature for setting the nitrogen gas content in the resin pellets to a desired value, for example, a temperature slightly higher than the environmental temperature Te outside the apparatus. Specifically, the temperature Ta after cooling may be, for example, 60°C or less, and may be 40°C or less in order to further increase the nitrogen gas content.

As shown in Fig. 5, in step S6, at least in the initial stage of cooling, the temperature of the resin pellets in the cooling hopper 40 is lowered more gently than natural cooling. This can be realized, for example, by setting the temperature of the refrigerant in the heat exchanger 53 to a temperature lower than the temperature of the resin pellets before cooling and higher than the temperature of the external environment.

In this way, when the temperature of the resin pellets is lowered more gently than natural cooling, the period during which the resin pellets are at a high temperature can be lengthened. At a high temperature, the saturated content of nitrogen gas in the resin pellets in an equilibrium state is low, but dissolution and diffusion of nitrogen molecules into the resin pellets occur more actively than at a low temperature. Therefore, by taking a long period of high temperature, the saturated content of the resin pellets can be increased while sufficiently containing nitrogen gas in the resin pellets. Thereby, content of the inert gas in the resin pellet after cooling can be increased more. As a result, it is possible to further suppress the occurrence of discoloration due to oxidation during injection molding, which will be described later.

Moreover, as shown in FIG. 5, in this embodiment, the temperature fall width per unit time of a resin pellet is enlarged with the lapse of time. In this way, while suppressing the total time required for cooling the resin pellets, the period during which the resin pellets are at a high temperature can be lengthened. Therefore, the temperature of the resin pellets can be reduced while the inert gas is sufficiently contained in the resin pellets, and the processing time can also be shortened.

When the resin pellets are cooled to the temperature Ta, the cooled resin pellets are discharged from the lower part of the cooling hopper 40, pass through the third conveying pipe 83, and are conveyed by energy to the gas phase hopper 60 (step S7). Then, in response to a request from the control unit 230 of the injection molding machine 2 , the control unit 70 of the pre-processing device 1 opens the on-off valve 62 . Thereby, the resin pellets are supplied from the gas phase hopper 60 through the supply pipe 61 into the cylinder 211 of the injection molding machine 2 (step S8).

At this time, due to the supply of nitrogen gas from the nitrogen gas supply unit 89, the pressure in the gas phase hopper 60 is more positive than the external environmental pressure. Then, nitrogen gas is continuously discharged from the vent port 63 of the supply pipe 61 to the outside through the check valve 631 . For this reason, even if the gas flows backward from the cylinder 211 of the injection molding machine 2 into the supply pipe 61, the said gas is discharged|emitted from the vent port 63 to the outside. Thereby, the contact of the gas component in the cylinder 211 with the resin pellet in the gaseous-phase hopper 60 is suppressed. Moreover, it can suppress that the temperature of the resin pellet rises before supply of the resin pellet to the cylinder 211.

When the resin pellets are supplied into the cylinder 211 , the control unit 230 of the injection molding machine 2 rotates the screw 212 in the cylinder 211 . As a result, the resin pellets move toward the injection nozzle 214 . Further, the resin pellets in the cylinder 211 are heated and melted by the heater 215 to become a flowable liquid (step S9).

At this time, the control unit 70 of the preprocessor 1 transmits the measurement result of the temperature sensor 64 to the control unit 230 of the injection molding machine 2 . Then, the control unit 230 of the injection molding machine 2 controls the output of the heater 215 based on the received measurement result. Thereby, the temperature of the resin pellets in front of the injection nozzle 214 is controlled to be substantially constant.

Specifically, for example, by comparing the measurement result of the temperature sensor 64 with a preset target temperature, if the measurement result is lower than the target temperature, the output of the heater 215 is increased, and if the measurement result is higher than the target temperature, Lower the output of the heater 215 . In this way, the melting position of the resin pellets in the cylinder 211 can be stabilized. Therefore, for example, by melting the resin pellets immediately before the injection nozzle 214, the period during which it is higher than the melting temperature can be shortened. As a result, discoloration by oxidation of resin can be suppressed more.

However, instead of the variable output heater 215, a heater having a constant output and capable of ON/OFF switching may be used. In this case, when the temperature in the cylinder 211 is lower than the set temperature, the heater is turned on, and when the temperature in the cylinder 211 is higher than the set temperature, the heater is turned off. In this case, based on the measurement result of the temperature sensor 64 near the supply port 213, you may change the set temperature used as the threshold value of ON/OFF of a heater. For example, when the measurement result of the temperature sensor 64 is lower than the target temperature, the set temperature in the cylinder 211 is increased, and when the measurement result of the temperature sensor 64 is higher than the target temperature, the set temperature in the cylinder 211 is lowered. . In this way, similarly to the above, the melting position of the resin pellets in the cylinder 211 can be stabilized.

Thereafter, the molten resin is injected from the injection nozzle 214 by the pressure generated by the advancement of the screw 212 , and is filled in the cavity space 293 in the mold apparatus 290 . Then, in the cavity space 293, the resin is cooled and solidified, whereby a resin product (a transparent optical component in this embodiment) is molded (step S10). Even when the resin is ejected from the injection nozzle 214, oxidation of the resin is unlikely to occur because the content of nitrogen gas in the resin is large. Accordingly, a resin product in which discoloration is suppressed can be obtained.

However, in the above description, although the process was demonstrated in order along the flow of a resin pellet, these processes may progress simultaneously. That is, different processes may be performed simultaneously with respect to some resin pellets and other resin pellets, and the process may be progressed continuously as a whole.

<3. Variant example>

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said embodiment.

6 is a graph showing the temperature change of the resin pellets in the cooling hopper 40 according to a modification. In the example of Fig. 6, at least in the initial stage of cooling, the temperature of the resin pellets is decreasing step by step. This can be realized by, for example, turning the heat exchanger 53 on and off intermittently. In this way, the period during which the resin pellets are maintained at a high temperature and at a substantially constant temperature can be long. Therefore, the temperature of the resin pellets can be reduced while sufficiently containing nitrogen gas in the resin pellets.

However, after cooling the resin pellets in the cooling hopper 40, there are cases where the resin pellets cannot be immediately discharged from the cooling hopper 40. In such a case, the resin pellets after cooling may be placed on standby in the cooling hopper 40 while controlling the temperature. For example, as shown in the graphs of FIGS. 7 and 8 , after cooling the resin pellets to the temperature Ta, in the cooling hopper 40, the resin pellets may be kept on standby while maintaining the temperature Ta. The maintenance of the temperature may be realized by operating the cooling mechanism 50 as a temperature control mechanism. In this way, the temperature of the resin pellets can be prevented from being lower than the target temperature Ta. Therefore, it is possible to always discharge the resin pellets from the cooling hopper 40 at a constant temperature (Ta).

Moreover, also between the cooling hopper 40 and the cylinder 211 of the injection molding machine 2, you may control the temperature of the resin pellet actively. For example, as shown in FIG. 9, a band heater 65 as a temperature control mechanism is mounted around the gas phase hopper 60 and the supply pipe 61, and the temperature of the resin pellets is approximately adjusted by the heat of the band heater 65. You may keep it constant. In this way, it can suppress that the temperature of the resin pellet discharged|emitted from the cooling hopper 40 falls in the gaseous-phase hopper 60 or the supply pipe 61. Therefore, the temperature of the resin pellets supplied to the cylinder 211 can be more stable. As a result, the resin product can be molded more stably. However, instead of the band heater 65, another temperature control mechanism such as a hot air supply mechanism may be used. In addition, as a temperature control mechanism around the supply pipe 61, instead of the band heater 65, an insulating material made of glass fiber, urethane foam, or silicone foam is provided, and the insulating material is used to produce resin pellets. The temperature of the may be kept approximately constant.

10 is a diagram showing the configuration of the pre-processing apparatus 1 and the injection molding machine 2 according to another modification. In the example of FIG. 7 , the cooling hopper 40 is disposed above the cylinder 211 of the injection molding machine 2 . And the cooling hopper 40 and the cylinder 211 are connected without passing through another hopper. The cooling hopper 40 and the cylinder 211 are connected through a supply pipe 61 , and a vent port 63 is provided in the supply pipe 61 . In this way, the resin pellets cooled in the cooling hopper 40 can be quickly supplied from the cooling hopper 40 to the cylinder 211 . Moreover, the number of hoppers can be reduced compared with said embodiment, and the pre-processing apparatus 1 can be comprised more compactly.

Moreover, in the said embodiment, although heat-drying and cooling of the resin pellet were performed in another hopper, you may make it perform these processes in a single hopper. That is, the heat-drying mechanism 30 and the cooling mechanism 50 are connected to one hopper, and you may make it perform the process from heat-drying to cooling in the inside of the said one hopper.

Moreover, in the said embodiment, although the resin pellet in the heating hopper 20 was heated by hot air, you may heat the resin pellet using other heating means, such as a band heater.

Moreover, although nitrogen gas was used as an inert gas in the said embodiment, what is necessary is just a gas which can suppress oxidation of a resin pellet by containing the inert gas of this invention in resin pellet. For example, instead of nitrogen gas, carbon dioxide or argon gas may be used as the inert gas.

In addition, the resin pellet used in the said embodiment is an example of a molding material. As the molding material, a material other than resin pellets may be used.

In addition, about the detailed structure of a pre-processing apparatus and an injection molding machine, you may differ from the structure shown in each figure of this application.

Moreover, you may combine each element which appeared in the said embodiment and a modified example suitably in the range which does not generate|occur|produce a contradiction.

1 Preprocessor
2 injection molding machine
10 Lead Hopper
20 Heating hopper
24 1st transfer hopper
30 Heat Drying Appliance
31 gas heating tube
32 blower
33 heat exchanger
40 cooling hopper
44 2nd transfer hopper
50 cooling mechanism
51 gas cooling tube
52 blower
53 heat exchanger
60 Weather Hopper
61 supply pipe
62 on/off valve
63 vent
64 temperature sensor
65 band heater
70 control
81 First return pipe
82 Second conveying pipe
83 3rd return pipe
84 first suction tube
85 second suction tube
86 3rd suction tube
87 confluence
88 blower
89 nitrogen gas supply
100 Resin product manufacturing system
210 injection device
211 cylinder
212 screw
213 inlet
214 injection nozzle
215 heater
216, 217, 225, 226, 227 motors
220 clamping device
230 control
290 Mold Equipment
291 fixed mold
292 Movable Mold
293 cavity space

Claims (29)

As a pre-processing method of a molding material supplied to a molding machine,
a) drying the molding material by heating;
b) a step of lowering the temperature of the molding material in a container filled with an inert gas after step a);
c) After the step b), the step of supplying a molding material to the molding machine
To have,
In the step b), while maintaining a constant pressure in the container, the temperature of the molding material is lowered,
In the step b), the pretreatment method of the molding material for lowering the temperature of the molding material more gently than natural cooling. delete As a pre-processing method of a molding material supplied to a molding machine,
a) drying the molding material by heating;
b) a step of lowering the temperature of the molding material in a container filled with an inert gas after step a);
c) After the step b), the step of supplying a molding material to the molding machine
To have,
In the step b), the pretreatment method of the molding material for lowering the temperature of the molding material more gently than natural cooling. 4. The method according to claim 1 or 3,
In the step b), the pretreatment method of the molding material in which the temperature drop per unit time of the molding material increases with the lapse of time. 4. The method according to claim 1 or 3,
In the step b), a pre-treatment method of the molding material for stepwise lowering the temperature of the molding material. 4. The method according to claim 1 or 3,
In the step b), a pretreatment method of a molding material for lowering the temperature of the molding material to 60° C. or less. 4. The method according to claim 1 or 3,
The pretreatment method of a molding material in which the pressure in the said container in the said process b) is higher than the environmental pressure outside the said container. 8. The method of claim 7,
The pressure in the container in the step b) is lower than the injection pressure of the molding material in the molding machine. 9. The method of claim 8,
The pressure in the container in the step b) is less than 1 MPa. 4. The method according to claim 1 or 3,
After the step b), the pretreatment method of the molding material further comprising a step of maintaining a constant temperature of the molding material before the step c). 4. The method according to claim 1 or 3,
d) A method for pre-processing a molding material, further comprising: measuring a temperature in the vicinity of a supply port to the molding machine, and controlling the temperature of the molding material in front of the injection nozzle in the molding machine based on the measured temperature. 4. The method according to claim 1 or 3,
A method of pre-processing a molding material for processing an optical part molding material. As a pre-processing device for the molding material supplied to the molding machine,
A cooling container for accommodating the molding material dried by heating therein;
a gas supply unit for filling the inside of the cooling vessel with an inert gas;
A cooling mechanism for lowering the temperature of the molding material accommodated in the cooling vessel
to provide
A preprocessing apparatus for a molding material in which the cooling mechanism lowers the temperature of the molding material more slowly than natural cooling while maintaining a constant pressure in the cooling vessel by supply of an inert gas from the gas supply unit. delete As a pre-processing device for the molding material supplied to the molding machine,
A cooling container for storing the molding material dried by heating therein;
a gas supply unit for filling the inside of the cooling vessel with an inert gas;
A cooling mechanism for lowering the temperature of the molding material stored in the cooling vessel
to provide
The cooling mechanism is a pre-processing device for a molding material that lowers the temperature of the molding material more gently than natural cooling. 16. The method according to claim 13 or 15,
On the upstream side of the conveyance path than the cooling vessel, a heating vessel for storing the molding material therein;
a heating drying mechanism for drying the molding material stored in the heating container by heating;
A conveying pipe for conveying the molding material from the heating vessel to the cooling vessel
A pre-processing device for molding materials further comprising a. 16. The method according to claim 13 or 15,
A vent port located between the cooling vessel or another vessel located downstream of the cooling vessel and the molding machine, and communicating with the outside
have additionally,
The pressure in the cooling vessel or the other vessel located downstream of the cooling vessel is higher than an external environmental pressure. 16. The method according to claim 13 or 15,
A pre-processing apparatus for a molding material further comprising a temperature control mechanism for maintaining a constant temperature of the molding material after being cooled by the cooling mechanism. 16. The method according to claim 13 or 15,
A pre-processing device for molding materials for optical parts. delete delete delete delete delete An injection molding method in which a molding material is melted and injected into a mold,
x) the process of supplying the pre-treated molding material to the cylinder through the supply port;
y) melting the molding material in the cylinder;
z) the process of injecting the molten molding material from the injection nozzle of the cylinder
To have,
In the step x), molding in which the temperature is lowered more gently than natural cooling in the container while maintaining the pressure in the container constant by supply of an inert gas in the container containing the molding material dried by heating An injection molding method for supplying a material to the cylinder through the supply port. delete An injection molding method in which a molding material is melted and injected into a mold,
x) the process of supplying the pre-treated molding material to the cylinder through the supply port;
y) melting the molding material in the cylinder;
z) the process of injecting the molten molding material from the injection nozzle of the cylinder
To have,
In the step x), an injection molding method in which a molding material whose temperature is lowered more gently than natural cooling in a container filled with an inert gas containing a molding material dried by heating is supplied to the cylinder through the supply port . 28. The method of claim 25 or 27,
In the step x), after the temperature in the container is lowered, the molding material maintained at a constant temperature is supplied to the cylinder through the supply port. 28. The method of claim 25 or 27,
In the step y), an injection molding method in which the temperature of the molding material in front of the injection nozzle in the cylinder is controlled based on the temperature in the vicinity of the supply port.

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