JP6449403B1 - Gas supply device - Google Patents

Abstract

Provided is a gas supply device capable of supplying an inert gas into a transport pipe while suppressing the biting of powder particles. The gas supply device includes a purge nozzle that discharges an inert gas into a transport pipe. The purge nozzle 512 extends from the outside of the transport pipe 21 toward the screw 22. A discharge port 63 provided at the tip of the purge nozzle 512 is located in the transport pipe 21. Further, a gap G of one or more powder particles is interposed between the discharge port 63 and the outer peripheral portion of the screw 22. For this reason, it is possible to efficiently supply the inert gas into the transport pipe 21 while suppressing the powder particles from being caught between the discharge port 63 of the purge nozzle 512 and the screw. [Selection] Figure 2

Description

  The present invention relates to a gas supply device that supplies an inert gas to a device that conveys a granular material by rotation of a screw disposed in the conveying tube while heating the granular material in the conveying tube.

  2. Description of the Related Art Conventionally, an injection molding machine heats resin pellets (powder particles) supplied from a preceding pellet supply apparatus while being conveyed by rotation of a screw in a conveyance tube. And the resin pellet fuse | melted by heating is inject | poured in a metal mold | die from a conveyance pipe. A conventional injection molding machine is described in Patent Document 1, for example.

JP-A-8-66938

  The inside of the transfer pipe of the injection molding machine becomes high temperature. For this reason, if oxygen is present in the transfer tube, the resin pellets may be oxidized. Oxidation of the resin pellets causes a defect such as discoloration in the molded resin product.

  As a method for preventing such oxidation of the resin pellets, it is conceivable to supply an inert gas into the transport pipe to lower the oxygen concentration in the transport pipe. For example, it is conceivable to insert a purge nozzle into the transport pipe and discharge nitrogen gas from the purge nozzle. At that time, in order to efficiently replace the air around the resin pellet in the transport pipe with nitrogen gas, it is preferable to arrange the discharge port of the purge nozzle close to the resin pellet in the transport pipe. However, if the discharge port of the purge nozzle is too close to the screw, resin pellets may be caught between the discharge port of the purge nozzle and the screw. Further, there is a possibility that the resin pellet enters the discharge port of the purge nozzle and becomes clogged.

  The present invention has been made in view of such circumstances, and efficiently supplies an inert gas into the transport pipe while suppressing the powdery body from being caught between the discharge port of the purge nozzle and the screw. An object of the present invention is to provide a gas supply device that can be used.

In order to solve the above problems, the first invention of the present application is directed to an inert gas for a device that conveys the granular material by rotation of a screw disposed in the conveying tube while heating the granular material in the conveying tube. A purge nozzle that discharges an inert gas into the transport pipe, the purge nozzle extending from the outside of the transport pipe toward the screw, and a discharge port provided at the tip of the purge nozzle. One or more gaps of the granular material are interposed between the discharge port and the outer peripheral portion of the screw, which are located in the transport pipe, and the discharge port has a flat cylindrical shape, and the discharge port The minor axis of the inner peripheral part is smaller than the outer dimension of the granular material .

  A second invention of the present application is the gas supply device according to the first invention, wherein the purge nozzle is refracted from the first tube portion located outside the transfer tube and the first tube portion toward the screw. A second pipe portion extending, and the discharge port is provided at a tip of the second pipe portion.

A third invention of the present application is the gas supply device of the first invention or the second invention , wherein a nozzle member having a cylindrical portion and the purge nozzle extending from an inner peripheral surface of the cylindrical portion, and the cylindrical portion are fitted. A holding member having a round hole; and a pair of annular plates that sandwich the cylindrical portion and are fixed to the holding member.

4th invention of this application is a gas supply apparatus of 3rd invention, Comprising: The said nozzle member further has an outflow port from which the gas in the said conveyance pipe flows out.

5th invention of this application is a gas supply apparatus of 4th invention, Comprising: The oxygen concentration meter which measures the oxygen concentration in the gas which flowed out from the said outflow port is further provided.

6th invention of this application is a gas supply apparatus of any one invention from 1st invention to 4th invention, Comprising: The supply piping part which supplies an inert gas to the said purge nozzle is further provided.

7th invention of this application is the gas supply apparatus of 6th invention, Comprising: The said supply piping part has a heating part which heats the inert gas supplied to the said purge nozzle.

The eighth invention of the present application is the gas supply device of the sixth invention or the seventh invention, wherein the supply pipe section has an oxygen concentration meter for measuring an oxygen concentration in an inert gas supplied to the purge nozzle.

A ninth invention of the present application is the gas supply device according to any one of the sixth invention to the eighth invention, wherein the supply pipe section measures a flow rate of an inert gas supplied to the purge nozzle. Is further provided.

A tenth invention of the present application is the gas supply device according to any one of the sixth to ninth inventions, wherein the supply piping section generates nitrogen gas as the inert gas and supplies the nitrogen gas to the piping. An inert gas generator is further provided.

According to the first to tenth inventions of the present application, it is possible to efficiently supply an inert gas into the transport pipe while suppressing the powder particles from being caught between the discharge port of the purge nozzle and the screw.

Further , according to the first to tenth aspects of the present invention , it is possible to prevent the granular material from entering the discharge port of the purge nozzle.

In addition , according to the first to tenth aspects of the present invention , the opening area of the discharge port can be maintained at a certain level or more while being inactive while suppressing the occurrence of turbulence while preventing the intrusion of the granular material into the discharge port. Gas can be discharged.

In particular, according to the third invention of the present application, the nozzle member can be easily replaced by removing the annular plate from the holding member.

In particular, according to the fourth invention of the present application, the gas in the transport pipe can be collected by the sampling nozzle provided in the nozzle member.

In particular, according to the seventh invention of the present application, it is possible to suppress a decrease in the temperature of the granular material before being charged into the transport pipe.

1 is a schematic view of an injection molding system. It is a fragmentary sectional view of an injection molding system. It is sectional drawing of a nozzle assembly. It is an exploded sectional view of a nozzle assembly. It is the figure which looked at the purge nozzle and the screw from the drive mechanism side. It is the figure which looked at the purge nozzle and screw which concern on a modification from the drive mechanism side. It is sectional drawing of the nozzle assembly which concerns on a modification. It is a fragmentary sectional view of the injection molding system concerning a modification.

<1. About injection molding system>
FIG. 1 is a schematic view of an injection molding system 1 including a gas supply device 30 according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the injection molding system 1. The injection molding system 1 sequentially conveys resin pellets that are powder particles, melts the resin pellets, injects them into the mold 40, and cures the resin in the mold 40, thereby providing a resin product. This is a manufacturing system. As shown in FIGS. 1 and 2, the injection molding system 1 includes a pellet supply device 10, an injection device 20, and a gas supply device 30.

  The pellet supply device 10 is a device that supplies resin pellets to the injection device 20. The pellet supply device 10 is disposed on the upper portion of the injection device 20. The pellet supply apparatus 10 includes a hopper 11 and a supply pipe 12. Resin pellets before supply are stored in the hopper 11. The supply pipe 12 extends downward from the lower end portion of the hopper 11. The supply pipe 12 is provided with an on-off valve 121. When the on-off valve 121 is opened, the resin pellets stored in the hopper 11 are supplied to the injection device 20 through the supply pipe 12.

  The pellet supply device 10 may have a mechanism for heating and drying the resin pellets in the hopper 11 and a mechanism for stirring the resin pellets in the hopper 11.

  The injection device 20 is a device that melts the resin pellets supplied from the pellet supply device 10 while being conveyed and injects them into the mold 40. The injection device 20 includes a transport pipe 21, a screw 22, a drive mechanism 23, and a heater 24. The conveyance tube 21 is a cylindrical container extending in the horizontal direction. A supply port 210 for receiving resin pellets supplied from the pellet supply device 10 is provided on the upper surface of the rear portion of the transport pipe 21. The lower end portion of the supply pipe 12 described above is connected to the supply port 210 via a nozzle assembly 31 described later.

  The screw 22 is disposed inside the transport pipe 21. As shown in FIG. 2, the screw 22 has a screw shaft 221 and a blade 222. The screw shaft 221 is disposed horizontally along the center of the transport pipe 21. The blades 222 protrude outward from the outer peripheral surface of the screw shaft 221. Further, the blades 222 spread in a spiral around the screw shaft 221.

  The end of the screw shaft 221 is connected to the drive mechanism 23. When the drive mechanism 23 is operated, the screw 22 rotates about the screw shaft 221. Thereby, the resin pellet in the conveyance pipe 21 is pushed by the blade | wing 222, and is conveyed to the metal mold | die 40 side.

  Further, the resin pellets in the transport pipe 21 are heated by the heater 24 while being transported by the screw 22. Thereby, the resin pellet is gradually melted. Thereafter, the molten resin is injected into the mold 40 from an injection port 211 provided at the tip of the transport pipe 21.

  The gas supply device 30 is a device that supplies nitrogen gas, which is an inert gas, into the inside of the transport pipe 21. As shown in FIGS. 1 and 2, the gas supply device 30 includes a nozzle assembly 31 and a supply piping portion 32 that supplies nitrogen gas to the nozzle assembly 31.

  FIG. 3 is a cross-sectional view of the nozzle assembly 31. FIG. 4 is an exploded sectional view of the nozzle assembly 31. As shown in FIGS. 2 to 4, the nozzle assembly 31 includes a nozzle member 51, a holding member 52, and a pair of annular plates 53 and 54.

  The nozzle member 51 includes a cylindrical portion 511 and a purge nozzle 512. The cylindrical portion 511 is a cylindrical portion that supports the purge nozzle 512. The cylindrical portion 511 has a gas introduction hole 513 that is a through hole for introducing nitrogen gas. The purge nozzle 512 is a thin cylindrical nozzle. The cylindrical portion 511 and the purge nozzle 512 are integrated into one member.

  The purge nozzle 512 of this embodiment is a substantially L-shaped nozzle having a first tube portion 61 and a second tube portion 62. The first pipe portion 61 extends horizontally from the inner peripheral surface of the cylindrical portion 511 toward the inside of the cylindrical portion 511 from the portion where the gas introduction hole 513 is provided. The second pipe portion 62 is refracted from the tip of the first pipe portion 61 and extends downward. A discharge port 63 for discharging nitrogen gas is provided at the distal end (lower end) of the second tube portion 62.

  As shown in FIG. 2, in a state where the gas supply device 30 is incorporated in the injection molding system 1, the cylindrical part 511 and the first pipe part 61 are located outside the transport pipe 21. The second pipe part 62 extends from the tip of the first pipe part 61 toward the screw 22 in the transport pipe 21. At least the discharge port 63 of the second pipe portion 62 is located in the transport pipe 21.

  The holding member 52 is a plate-like member that holds the nozzle member 51. The holding member 52 has a circular hole 520 that is a through hole in the center. As shown in FIG. 2, the holding member 52 is disposed between the upper surface around the supply port 210 of the transport pipe 21 and the lower end portion of the supply pipe 12. And the conveyance pipe 21, the holding member 52, and the supply pipe | tube 12 are mutually fixed by fixing tools (illustration omitted), such as a screw. The holding member 52 is provided with a vent hole 521. The vent hole 521 extends in the horizontal direction between the outer end surface and the inner peripheral surface of the holding member 52. The cylindrical portion 511 of the nozzle member 51 is fitted into the circular hole 520 of the holding member 52 so that the vent hole 521 and the gas introduction hole 513 overlap.

  The annular plates 53 and 54 are members for fixing the nozzle member 51 to the holding member 52. Each of the annular plates 53 and 54 has an annular shape and a plate shape thinner than the holding member 52. One annular plate 53 is disposed below the cylindrical portion 511 of the nozzle member 51 fitted into the holding member 52. The other annular plate 54 is disposed on the upper portion of the cylindrical portion 511 of the nozzle member 51 fitted in the holding member 52. That is, the cylindrical portion 511 is sandwiched between the pair of annular plates 53 and 54 in the vertical direction. The pair of annular plates 53 and 54 are fixed to the holding member 52 by a fixing tool (not shown) such as a screw. Thereby, the nozzle member 51, the holding member 52, and a pair of annular plates 53 and 54 are mutually fixed.

  As the material of the nozzle member 51, the holding member 52, and the pair of annular plates 53, 54, for example, a metal such as stainless steel is used. However, some or all of these members may be formed of a material other than metal.

  The supply piping unit 32 is a piping system for supplying nitrogen gas to the purge nozzle 512. As shown in FIG. 2, the supply piping unit 32 of this embodiment includes a nitrogen gas generation unit 321, a flow rate adjustment unit 322, a flow meter 323, an oxygen concentration meter 324, and a heating unit 325. The flow rate adjustment unit 322, the flow meter 323, the oxygen concentration meter 324, and the heating unit 325 are provided in this order from the upstream side on the path of the pipe 320 that connects the nitrogen gas generation unit 321 and the vent hole 521 of the holding member 52. It is done.

  The nitrogen gas generator 321 separates and generates nitrogen gas from air using a nitrogen separation membrane. The flow rate adjustment unit 322 adjusts the flow rate of nitrogen gas flowing through the pipe 320. The flow meter 323 measures the flow rate of nitrogen gas flowing through the pipe 320. The oxygen concentration meter 324 measures the oxygen concentration in the nitrogen gas flowing through the pipe 320. The heating unit 325 includes a heater that heats the nitrogen gas that flows through the pipe 320 and a temperature sensor that measures the temperature of the nitrogen gas. The nitrogen gas generator 321 does not necessarily have to use a nitrogen separation membrane. For example, a deep-cooling type or PSA type nitrogen gas generator or a nitrogen cylinder may be used.

  Nitrogen gas supplied from the nitrogen gas generation unit 321 to the pipe 320 is introduced into the vent hole 521 and the gas introduction hole 513 through the flow rate adjustment unit 322, the flow meter 323, the oxygen concentration meter 324, and the heating unit 325 described above. Is done. Then, the introduced nitrogen gas passes through the purge nozzle 512 and is discharged from the discharge port 63 to the inside of the transport pipe 21. Thereby, the air inside the transport pipe 21 is replaced with nitrogen gas. As a result, the oxygen concentration in the internal space of the transport pipe 21 is reduced, and the oxidation of the resin pellets is suppressed.

  FIG. 5 is a view of the purge nozzle 512 and the screw 222 as viewed from the drive mechanism 23 side. As shown in FIGS. 2 and 5, the discharge port 63 of the purge nozzle 512 is disposed in the vicinity of the screw 22 inside the transport pipe 21. For this reason, the nitrogen gas discharged from the discharge port 63 is stirred by the screw 22 and efficiently spreads in the transport pipe 21. Therefore, the air in the transport pipe 21 is more efficiently replaced with nitrogen gas.

  However, as shown in the enlarged view in FIG. 2 and FIG. 5, a gap G is provided between the discharge port 63 of the purge nozzle 512 and the outer peripheral portion of the screw 22 (the outer end of the blade 222). For this reason, the purge nozzle 512 can discharge nitrogen gas into the transport pipe 21 without contacting the screw 22. Further, the gap G has a dimension equal to or larger than one resin pellet to be processed (an average value of the outer diameter of the resin pellet). In this way, it is possible to prevent the resin pellets from being caught between the discharge port 63 of the purge nozzle 512 and the outer end of the blade 222. It is more preferable that the gap G is equal to or more than two resin pellets. Specifically, the size of the gap G may be set to 5 mm or more, for example.

  As shown in FIG. 3, in this embodiment, the discharge port 63 of the purge nozzle 512 has a flat cylindrical shape. Specifically, the inner peripheral portion of the discharge port 63 is elliptical when viewed from below. As described above, when the discharge port 63 has a flat cylindrical shape, the opening area of the discharge port 63 can be maintained at a certain level or more while preventing the granular material from entering the discharge port 63. Therefore, the inert gas can be discharged while suppressing the generation of turbulent flow. It is preferable that at least the minor axis of the inner peripheral portion of the discharge port 63 is smaller than the outer dimension of the resin pellet to be processed.

  Further, as described above, the nozzle member 51 of the present embodiment is fixed to the holding member 52 by the cylindrical portion 511 being sandwiched between the pair of annular plates 53 and 54. For this reason, the nozzle member 51 can be easily attached and detached by removing the annular plates 53 and 54 from the holding member 52. Therefore, maintenance such as cleaning of the nozzle member 51 is easy. It is also possible to prepare a plurality of nozzle members 51 having different dimensions of the purge nozzle 512 in advance and replace these nozzle members 51 depending on the situation.

  Further, the gas supply device 30 of this embodiment includes a heating unit 325 that heats an inert gas supplied to the purge nozzle 512. Thereby, high-temperature nitrogen gas can be discharged from the purge nozzle 512. A part of the discharged high-temperature nitrogen gas spreads in the vicinity of the supply port 210. For this reason, it can suppress that the temperature of the resin pellet before thrown into the conveyance pipe 21 falls. In particular, in the present embodiment, the heating unit 325 is disposed immediately before the purge nozzle 512 (the most downstream portion of the pipe 320). For this reason, the inert gas supplied to the purge nozzle 512 can be efficiently heated.

  In addition, it is preferable that the temperature of the nitrogen gas discharged from the purge nozzle 512 is higher than normal temperature (environment temperature around the injection molding system 1). The temperature of the nitrogen gas discharged from the purge nozzle 512 is preferably lower than the melting point of the resin pellets in order to prevent the resin pellets from being immediately melted by blowing nitrogen gas.

  Further, the gas supply device 30 of the present embodiment includes a flow meter 323 and a flow rate adjustment unit 322. For this reason, the discharge amount of nitrogen gas from the purge nozzle 512 can be adjusted by operating the flow rate adjusting unit 322 based on the measurement result of the flow meter 323. If the discharge amount of nitrogen gas from the purge nozzle 512 is too small, the air in the transport pipe 21 cannot be efficiently replaced with nitrogen gas. On the other hand, if the discharge amount of the nitrogen gas from the purge nozzle 512 is too large, turbulent flow of nitrogen gas occurs in the transport pipe 21, which may cause outside air to be caught from the gap in the transport pipe 21. Therefore, it is preferable that the discharge amount of nitrogen gas from the purge nozzle 512 is adjusted to an amount that can efficiently replace the air in the transport pipe 21 with nitrogen gas and that does not easily involve outside air. In order to suppress the intrusion of outside air, it is preferable that the air pressure inside the transport pipe 21 is a positive pressure rather than the outside air pressure.

<2. Modification>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

  FIG. 6 is a view of the purge nozzle 512 and the screw 22 according to one modification as viewed from the drive mechanism 23 side. In the example of FIG. 6, the discharge port 63 of the purge nozzle 512 is arranged at a position shifted from directly above the screw shaft 221. As described above, the position of the discharge port 63 may not be directly above the screw shaft 221. It is sufficient that the minimum dimension of the gap G between the discharge port 63 and the screw 22 is equal to or more than one particle. However, in that case, the discharge port 63 is connected to the screw 22 from the position directly above the screw shaft 221 so that the discharge direction of the nitrogen gas from the discharge port 63 coincides with the rotation direction of the screw 22. It is preferable to arrange at a position shifted in the rotation direction. Thereby, the stirring effect of the nitrogen gas by the blades 222 of the screw 22 can be obtained satisfactorily.

  FIG. 7 is a cross-sectional view of a nozzle assembly 31 according to another modification. FIG. 8 is a partial cross-sectional view of the injection molding system 1 having the nozzle assembly 31. In the example of FIGS. 7 and 8, the nozzle member 51 includes a purge nozzle 512 and a sampling nozzle 514. The purge nozzle 512 is used to discharge nitrogen gas into the transport pipe 21 as in the above embodiment. The sampling nozzle 514 is used for collecting the gas in the transport pipe 21. An outlet 515 is provided at the tip of the sampling nozzle 514.

  When the sampling nozzle 514 is used, part of the gas in the transport pipe 21 flows out from the outlet 515 into the sampling nozzle 514. Then, the gas flows from the sampling nozzle 514 through the outflow pipe 326 to the oximeter 324 as shown in FIG. In this way, it is possible to measure the oxygen concentration of the gas collected from the inside of the transport pipe 21. Therefore, the oxygen concentration of the nitrogen gas discharged from the purge nozzle 512 can be adjusted according to the measurement result. Note that the pipes 320 and 326 connected to the oxygen concentration meter 324 may be appropriately switched using a valve (not shown). Moreover, you may measure characteristic values (for example, temperature) other than the oxygen concentration of the extract | collected gas.

  The sampling nozzle 514 may be used as a path for discharging air from the inside of the transport pipe 21 to the outside when the air in the transport pipe 21 is replaced with nitrogen gas. Since the atmospheric pressure in the transport pipe 21 becomes a positive pressure by supplying nitrogen gas, air is naturally discharged from the transport pipe 21 to the sampling nozzle 514. However, the air in the transport pipe 21 may be actively sucked into the sampling nozzle 514 using a vacuum pump or the like. Then, the replacement speed from air to nitrogen gas can be increased. Further, the outgas generated from the resin pellet in the transport pipe 21 may be discharged to the outside through the sampling nozzle 514.

  In the above embodiment, the discharge port 63 of the purge nozzle 512 has an elliptical shape. However, the discharge port 63 of the purge nozzle 512 may have another shape such as a circle.

  In the above embodiment, nitrogen gas is used as the inert gas. However, instead of nitrogen gas, another gas having a low oxygen concentration may be used as the inert gas.

  Moreover, you may combine suitably each element which appeared in said embodiment or modification in the range which does not produce inconsistency.

DESCRIPTION OF SYMBOLS 1 Injection molding system 10 Pellet supply apparatus 11 Hopper 12 Supply pipe 20 Injection apparatus 21 Conveyance pipe 22 Screw 23 Drive mechanism 24 Heater 30 Gas supply apparatus 31 Nozzle assembly 32 Supply piping part 40 Mold 51 Nozzle member 52 Holding member 53 Annular plate 54 Annular plate 61 First pipe part 62 Second pipe part 63 Discharge port 121 On-off valve 210 Supply port 211 Injection port 221 Screw shaft 222 Blade 320 Piping 321 Nitrogen gas generating part 322 Flow rate adjusting part 323 Flow meter 324 Oxygen meter 325 Heating part 511 Cylindrical portion 512 Purge nozzle 513 Gas introduction hole 514 Sampling nozzle 520 Circular hole 521 Vent hole G Gap

Claims (10)

A gas supply device that supplies an inert gas to a device that conveys the granular material by rotation of a screw disposed in the conveying tube while heating the granular material in the conveying tube,
A purge nozzle for discharging an inert gas into the transport pipe;
The purge nozzle extends from the outside of the transport pipe toward the screw, and a discharge port provided at the tip thereof is located in the transport pipe.
Between the discharge port and the outer periphery of the screw, there is a gap of one or more of the powder particles ,
The discharge port has a flat cylindrical shape,
A gas supply device in which a minor axis of an inner peripheral portion of the discharge port is smaller than an outer dimension of the granular material . The gas supply device according to claim 1,
The purge nozzle is
A first pipe portion located outside the transport pipe;
A second pipe part that refracts from the first pipe part and extends toward the screw;
Have
A gas supply device in which the discharge port is provided at a tip of the second pipe portion. The gas supply device according to claim 1 or 2, wherein
A nozzle member having a cylindrical portion and the purge nozzle extending from an inner peripheral surface of the cylindrical portion;
A holding member having a circular hole into which the cylindrical portion is fitted;
While sandwiching the cylindrical portion, a pair of annular plates fixed to the holding member;
A gas supply device comprising: The gas supply device according to claim 3,
The nozzle member is
Outlet through which gas in the transfer pipe flows out
A gas supply device further comprising: The gas supply device according to claim 4,
Oxygen concentration meter for measuring oxygen concentration in gas flowing out from the outlet
A gas supply device further comprising: The gas supply device according to any one of claims 1 to 4, wherein:
Supply piping section for supplying inert gas to the purge nozzle
A gas supply device further comprising: The gas supply device according to claim 6,
The supply piping section is
A heating unit for heating the inert gas supplied to the purge nozzle
A gas supply device. The gas supply device according to claim 6 or 7, wherein
The supply piping section is
An oxygen concentration meter for measuring the oxygen concentration in the inert gas supplied to the purge nozzle
A gas supply device. A gas supply device according to any one of claims 6 to 8,
The supply piping section is
A flow meter for measuring the flow rate of the inert gas supplied to the purge nozzle
A gas supply device further comprising: A gas supply device according to any one of claims 6 to 9,
The supply piping section is
Inert gas generator that generates nitrogen gas as the inert gas and supplies it to the piping
A gas supply device further comprising:

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