Powder and granular material processing apparatus

Abstract

To provide a powder and granular material processing device capable of drying powder and granular material while suppressing the influence of outside air.SOLUTION: The powder and granular material processing device 1 conveys the powder and granular material from the storage container 10 to the drying container 30 and dries the powder and granular material with hot air in the drying container 30. In addition, the powder and granular material processing device 1 includes the pressure reduction mechanism 20 that reduces the pressure of the gas inside the storage container 10. By reducing the pressure of the gas in the storage container 10, the influence of the outside air on the granular material before being conveyed to the drying container 30 can be suppressed, and the state of the granular material can be made uniform. In addition, by reducing the pressure of the gas inside the storage container 10, the moisture content of the granular material before being conveyed to the drying container 30 can be reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a powder or granular material processing apparatus that dries powder or granular materials (hereinafter referred to as "powder or granular materials") using hot air. [Background technology]

[0002] Conventionally, in the molding process of plastic products, a powder processing apparatus is used that dries powder or granules such as resin pellets with hot air and supplies the dried powder or granules to an injection molding machine. A conventional powder or granule processing apparatus is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-30190 Summary of the Invention [Problem to be solved by the invention]

[0004] In the powder and granular material processing apparatus of Patent Document 1, powder and granular material is dried using hot air in an environment of nitrogen gas, which is an inert gas. This allows the powder and granular material to be dried while suppressing moisture absorption and oxidation of the powder and granular material due to the outside air. However, in recent years, the quality requirements for molded products have been increasing, and there are cases where the quality requirements cannot be met simply by drying using the above-mentioned nitrogen gas.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a powder or granular material processing apparatus that can dry powder or granular material while further suppressing the influence of outside air compared to conventional apparatuses. [Means for solving the problem]

[0006] The first invention of the present application comprises a storage container for storing powdered or granular material, a drying container for drying the powdered or granular material downstream of the storage container in the conveying direction, a conveying pipe connecting the storage container and the drying container, an airflow generating means for generating an airflow from the storage container to the drying container within the conveying pipe, a hot air supplying means for supplying hot air to the drying container, an inert gas introduction section for introducing at least an inert gas into the drying container, and a pressure reducing mechanism for reducing the pressure of the gas in the storage container.

[0007] The second invention of the present application is a powder and granular material processing apparatus of the first invention, further comprising a switching means for switching the storage container between a first state in which the storage container is disconnected from the conveying pipe and connected to the pressure reduction mechanism, and a second state in which the storage container is disconnected from the pressure reduction mechanism and connected to the conveying pipe.

[0008] A third invention of the present application is the powder / granular material processing apparatus of the second invention, which comprises a plurality of the storage containers, and the storage container in the first state and the storage container in the second state are interchangeable.

[0009] A fourth invention of the present application is the powder or granular material processing apparatus of the third invention, wherein the inert gas introducing section further introduces an inert gas into the storage container in the second state.

[0010] The fifth invention of the present application is a powder and granular material processing device of the fourth invention, further comprising a circulation line connected to the conveying pipe, and the inert gas introduced from the inert gas introduction section is circulated in the circulation line.

[0011] The sixth invention of the present application is a powder and granular material processing apparatus according to the fourth or fifth invention, wherein the storage container has a connection port that is connected to the pressure reduction mechanism in the first state and that is connected to the inert gas introduction section in the second state.

[0012] A seventh aspect of the present invention is a powder or granular material processing apparatus according to any one of the second to fifth aspects, further comprising a heater for heating the powder or granular material stored in the storage container in the first state.

[0013] The eighth invention of the present application is a powder or granular material processing device according to any one of the second to fifth inventions, wherein the inert gas introduction section further introduces an inert gas into the storage container in the first state. [Effects of the Invention]

[0014] According to the first to eighth aspects of the present invention, by lowering the gas pressure in the storage container, it is possible to suppress the influence of outside air on the powder or granular material before it is transferred to the drying container and to make the state of the powder or granular material uniform. Furthermore, by lowering the gas pressure in the storage container, it is possible to reduce the moisture content of the powder or granular material before it is transferred to the drying container.

[0015] In particular, according to the third aspect of the present invention, while one storage container is in the second state and supplying powder or granular material to the conveying pipe, another storage container can be in the first state and depressurized. Then, the storage container that has finished supplying powder or granular material can be replaced with the storage container that has finished depressurizing. This allows the powder or granular material to be continuously supplied to the conveying pipe.

[0016] In particular, according to the fourth aspect of the present invention, the humidity and oxygen concentration of the gas inside the storage container can be kept low, thereby suppressing moisture absorption and oxidation of the powder or granular material inside the storage container.

[0017] In particular, according to the fifth aspect of the present invention, the humidity and oxygen concentration of the gas inside the conveying pipe can be kept low, thereby suppressing moisture absorption and oxidation of the powder or granular material inside the conveying pipe.

[0018] In particular, according to the sixth aspect of the present invention, the pressure reducing mechanism and the inert gas introducing section are connected to a common connection port, which makes it possible to reduce the number of connection ports. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing the configuration of a powder and granular material processing apparatus. [Figure 2]FIG. 2 is a control block diagram of the powder and granular material processing apparatus. [Figure 3] 1 is a flowchart showing an example of processing in a powder or granular material processing apparatus. [Figure 4] FIG. 10 is a diagram showing the configuration of a powder or granular material processing apparatus according to a second modified example. [Figure 5] FIG. 10 is a diagram showing the configuration of a powder or granular material processing apparatus according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0021] <1. Configuration of powder and granular processing equipment> 1 is a diagram showing the configuration of a powder or granular material processing apparatus 1 according to one embodiment of the present invention. This powder or granular material processing apparatus 1 is an apparatus that dries resin pellets 9, which are powder or granular material, and supplies the dried resin pellets 9 to a downstream injection molding machine 2.

[0022] The powder and granular material processing apparatus 1 processes resins that are significantly affected by moisture and oxygen during molding. For example, the powder and granular material processing apparatus 1 can process resin pellets for optical products. Resin pellets for optical products are those that transmit 90% or more of visible light, and specific examples include polycarbonate, COP (cycloolefin polymer), acrylic, etc. The resin pellets 9 discharged from the powder and granular material processing apparatus 1 are molded in an injection molding machine 2 to become transparent optical products such as light guide plates. In molding transparent optical products, preventing defects such as discoloration caused by moisture absorption or oxidation and appearance defects such as foreign matter is a particularly important quality control item. However, the powder and granular material to be processed in the present invention is not limited to resin pellets for optical products.

[0023] As shown in FIG. 1, the powder and granular material processing apparatus 1 of this embodiment has a storage container 10, a pressure reduction mechanism 20, a drying container 30, a conveying pipe 40, a conveying circulation line 50, a drying circulation line 60, an inert gas introduction section 70, and a control section 80.

[0024] The storage container 10 is a container that stores resin pellets before they are transported to the drying container 30. The storage container 10 is, for example, a hopper. It is desirable that the storage container 10 has airtightness and pressure resistance that allows it to maintain a reduced pressure state of approximately -100 to -60 kPa in gauge pressure. The storage container 10 has a storage container body 11 that has an opening at the top, and a lid 12 placed on top of the storage container body 11.

[0025] The storage container body 11 has a substantially cylindrical sidewall and a funnel-shaped bottom that gradually converges downward from the lower end of the sidewall. A space for storing resin pellets 9 is provided inside the storage container body 11. A discharge port 13 for discharging the resin pellets 9 is provided at the bottom of the storage container body 11. The lid 12 closes the opening at the top of the storage container body 11. When the lid 12 is removed, the top of the storage container body 11 is opened, allowing the resin pellets 9 to be poured into the storage container body 11.

[0026] The storage container 10 is mounted on a wheeled carriage 15. The carriage 15 can move the storage container 10 between a first position P1 and a second position P2. The first position P1 is a position where the storage container 10 can be connected to a pressure reducing mechanism 20. The second position P2 is a position where the storage container 10 can be connected to a transfer pipe 40.

[0027] The pressure reducing mechanism 20 is a mechanism that reduces the pressure of the gas inside the storage container 10. The pressure reducing mechanism 20 is connected to the storage container 10 that is disposed at the first position P1. Hereinafter, the state in which the storage container 10 is disconnected from the transfer pipe 40 and connected to the pressure reducing mechanism 20 will be referred to as the "first state." In the first state, the outlet 13 of the storage container 10 is blocked by a cap or a loop-shaped pipe.

[0028] As shown in FIG. 1, the decompression mechanism 20 has a suction pipe 21 and a decompression pump 22. The storage container 10 has a connection port 14. One end of the suction pipe 21 is connected to the connection port 14 of the storage container 10 disposed at the first position P1. The other end of the suction pipe 21 is connected to the decompression pump 22. When the decompression pump 22 is operated, the gas in the storage container 10 is discharged to the outside through the suction pipe 21. This reduces the pressure of the gas in the storage container 10. In addition, the suction pipe 21 is provided with an on-off valve (not shown). By closing the on-off valve, the pressure in the storage container 10 can be maintained.

[0029] The drying container 30 is a container for heating and drying the resin pellets 9. The drying container 30 is located downstream of the storage container 10 in the conveying direction of the resin pellets 9. The drying container 30 is, for example, a hopper. The drying container 30 has a substantially cylindrical side wall 31, a funnel-shaped bottom 32 that gradually converges downward from the lower end of the side wall 31, and a top plate 33 that covers the upper part of the drying container 30. A space for storing and drying the resin pellets 9 is provided inside the drying container 30.

[0030] A transfer hopper 34 is installed on the top of the drying container 30. The transfer hopper 34 is a container that temporarily stores the resin pellets 9 when the resin pellets 9 are supplied to the drying container 30. The transfer hopper 34 is connected to the drying container 30 via an openable and closable inlet 331 provided in the top plate 33 of the drying container 30. In addition, the downstream end of a transfer pipe 40 is connected to the side of the transfer hopper 34.

[0031] Meanwhile, a discharge pipe 35 for discharging the resin pellets 9 from the drying container 30 is connected to the lower part of the drying container 30. The discharge pipe 35 extends downward from a discharge port 321 provided in the bottom part 32 of the drying container 30. The lower end of the discharge pipe 35 is connected to the injection molding machine 2. In addition, the discharge pipe 35 is provided with a discharge valve 36 that switches the discharge port 321 between open and closed states.

[0032] The conveying pipe 40 is a pipe for conveying the resin pellets 9 between the storage container 10 and the drying container 30. The upstream end of the conveying pipe 40 in the conveying direction is connected to the discharge outlet 13 of the storage container 10 disposed at the second position P2. Hereinafter, the state in which the storage container 10 is disconnected from the pressure reducing mechanism 20 and connected to the conveying pipe 40 is referred to as the "second state." In this embodiment, a switching means for switching the storage container 10 between the first state and the second state is configured by a dolly 15 or the like.

[0033] The downstream end of the conveying pipe 40 in the conveying direction is connected to the conveying hopper 34. That is, the storage container 10 in the second state and the drying container 30 are connected by the conveying pipe 40 and the conveying hopper 34. The resin pellets 9 discharged from the storage container 10 are conveyed to the conveying hopper 34 by the airflow generated in the conveying pipe 40.

[0034] The transfer circulation line 50 is a piping system that circulates gas to generate an airflow toward the transfer hopper 34 within the transfer pipe 40. One end of the transfer circulation line 50 is connected to the top of the transfer hopper 34. The other end of the transfer circulation line 50 is connected to the transfer pipe 40.

[0035] A filter 341 is provided at the connection between the transfer circulation line 50 and the transfer hopper 34. The filter 341 has a plurality of through holes that restrict the passage of the resin pellets 9 and allow the passage of gas and fine powder. The filter 341 may separate the resin pellets 9 from the fine powder by using centrifugal force.

[0036] The transfer circulation line 50 is provided with a transfer blower 51, which is an airflow generating means, and a filter 52. When the transfer blower 51 is operated, an airflow is generated in the transfer circulation line 50 from the transfer hopper 34 to the transfer pipe 40, as shown by arrow A1 in Fig. 1. Then, an airflow is generated in the transfer pipe 40 from the storage container 10 to the transfer hopper 34, as shown by arrow A2 in Fig. 1. The resin pellets 9 discharged from the storage container 10 are forcefully transported to the transfer hopper 34 by the airflow.

[0037] Of the resin pellets 9, fine powder, and gas that flow into the transfer hopper 34, the fine powder and gas pass through the filter 341 and are sucked into the transfer circulation line 50. The fine powder is then collected by the filter 52 on the transfer circulation line 50. On the other hand, the resin pellets 9 are blocked by the filter 341 and are therefore stored in the transfer hopper 34 without flowing into the transfer circulation line 50.

[0038] After the resin pellets 9 have been stored in the transport hopper 34, when the pneumatic transport is stopped, the inlet 331 is opened and the resin pellets 9 are fed from the transport hopper 34 into the drying container 30 through the inlet 331. In this way, by repeating the pneumatic transport of the resin pellets 9 from the storage container 10 to the drying container 30 and the opening of the inlet 331, the resin pellets 9 are stored in the drying container 30.

[0039] The drying circulation line 60 is a piping system that circulates gas to supply hot drying air into the drying container 30. One end of the drying circulation line 60 is connected to a suction port 332 provided on the top plate 33 of the drying container 30. The other end of the drying circulation line 60 passes through the side wall 31 of the drying container 30 and is connected to an air outlet 64 disposed inside the drying container 30. The drying circulation line 60 is also provided with a filter 61, a drying blower 62, and a heater 63.

[0040] When the drying blower 62 is operated, an airflow is generated in the drying circulation line 60 from the suction port 332 toward the outlet 64, as shown by arrow A3 in FIG. 1 . Fine powder sucked into the drying circulation line 60 from the drying container 30 is collected by the filter 61. The gas that has passed through the filter 61 is heated by the heater 63 to become hot air. The hot air is then blown into the drying container 30 through the outlet 64. That is, in this embodiment, the drying circulation line 60 including the heater 63 constitutes a hot air supplying means that supplies hot air to the drying container 30. An absorber that adsorbs moisture contained in the gas may be provided between the filter 61 and the heater 63.

[0041] The hot air blown out from the air outlet 64 passes through gaps between the resin pellets 9 stored inside the drying container 30 and diffuses into the drying container 30. This heats the resin pellets 9, evaporating moisture from the resin pellets 9 and drying the resin pellets 9. That is, moisture is transferred from the resin pellets 9 and carried away by the gas diffused inside the drying container 30. The hygroscopic gas inside the drying container 30 is sucked out again into the drying circulation line 60 from the drying container 30 through the suction port 332. However, to prevent an increase in humidity in the circulating gas, the hygroscopic gas is discharged little by little from an exhaust port (not shown) and is replaced with inert gas introduced into the path as described below.

[0042] The inert gas introduction section 70 is a mechanism that introduces nitrogen gas, which is an inert gas, into each section of the powder and granular material processing apparatus 1. The inert gas introduction section 70 has a first air supply pipe 71, a second air supply pipe 72, and a nitrogen gas generator 74. The nitrogen gas generator 74 generates dry nitrogen gas. The upstream end of the first air supply pipe 71 is connected to the nitrogen gas generator 74. The downstream end of the first air supply pipe 71 is connected to the discharge pipe 35 of the drying container 30.

[0043] An on-off valve 711 is provided in the first air supply pipe 71. When the on-off valve 711 is opened, nitrogen gas is introduced from the nitrogen gas generator 74 through the first air supply pipe 71 into the discharge pipe 35. Furthermore, when nitrogen gas continues to be introduced from the inert gas introduction part 70, the nitrogen gas flows from the discharge pipe 35 into the drying container 30. The nitrogen gas is then circulated in the drying container 30 and the drying circulation line 60.

[0044] This keeps the humidity and oxygen concentration of the gas inside the drying container 30 low. This makes it possible to suppress moisture absorption and oxidation of the resin pellets 9 inside the drying container 30. Furthermore, by supplying nitrogen gas, the pressure of the gas inside the drying container 30 becomes higher than the outside air pressure. This makes it possible to suppress the intrusion of outside air into the drying container 30. As a result, it is possible to further suppress moisture absorption and oxidation of the resin pellets 9 inside the drying container 30.

[0045] The upstream end of the second air supply pipe 72 is connected to a nitrogen gas generator 74. The downstream end of the second air supply pipe 72 is connected to a connection port 14 of a storage container 10 disposed at the second position P2. The connection port 14 is connected to the pressure reduction mechanism 20 at the first position P1, and is connected to the inert gas introduction part 70 at the second position P2. In this way, by connecting the pressure reduction mechanism 20 and the inert gas introduction part 70 to a common connection port 14, the number of connection ports can be reduced.

[0046] An on-off valve 721 is provided in the second air supply pipe 72. When the on-off valve 721 is opened, nitrogen gas is introduced from the nitrogen gas generator 74 through the second air supply pipe 72 into the interior of the storage container 10 in the second state. This keeps the humidity and oxygen concentration of the gas inside the storage container 10 low. This makes it possible to suppress moisture absorption and oxidation of the resin pellets 9 inside the storage container 10. Furthermore, the supply of nitrogen gas makes the pressure of the gas inside the storage container 10 higher than the outside air pressure. This makes it possible to suppress the intrusion of outside air into the interior of the storage container 10. As a result, it is possible to further suppress moisture absorption and oxidation of the resin pellets 9 stored in the storage container 10.

[0047] Furthermore, when nitrogen gas continues to be introduced into the storage container 10 from the inert gas introduction part 70, the nitrogen gas flows out of the storage container 10 into the transfer pipe 40 and is circulated through the transfer pipe 40 and the transfer circulation line 50. This keeps the humidity and oxygen concentration of the gas in the transfer pipe 40 low. As a result, moisture absorption and oxidation of the resin pellets 9 can be suppressed even in the transfer pipe 40.

[0048] In this way, the powder / granular material processing apparatus 1 of this embodiment can fill the entire transport path of the resin pellets 9, from the storage container 10 through the transport pipe 40, the transport hopper 34, and the drying container 30 to the discharge pipe 35, with dry nitrogen gas. The oxygen concentration in the gas in the transport path is set to, for example, 1% or less. This makes it possible to suppress moisture absorption and oxidation of the resin pellets 9 in the powder / granular material processing apparatus 1. Note that the positions to which the downstream ends of the air supply pipes 71 and 72 are connected are not limited to those shown in FIG. 1. The air supply pipes 71 and 72 may be connected to any other positions as long as the space containing the resin pellets 9, including the transport path, the storage container 10, and the drying container 30, can be filled with nitrogen gas.

[0049] FIG. 2 is a control block diagram of the powder / granular material processing apparatus 1. The control unit 80 is a unit for controlling the operation of each part of the powder / granular material processing apparatus 1. As shown in FIG. 2, the control unit 80 is electrically connected to the above-mentioned pressure reducing pump 22, discharge valve 36, conveying blower 51, drying blower 62, heater 63, nitrogen gas generator 74, on-off valve 711, and on-off valve 721. The control unit 80 may be configured by a computer having a processor such as a CPU and memory, or may be configured by an electronic circuit. The control unit 80 controls the operation of each of the above-mentioned parts based on a preset program or an external input signal. This allows the processing of resin pellets 9 in the powder / granular material processing apparatus 1 to proceed.

[0050] The discharge valve 36, the on-off valve 711, and the on-off valve 721 may be separated from the control unit 80 so that the user can manually open and close them.

[0051] <2. Operation of powder and granular processing equipment> Next, a description will be given of the processing of the resin pellets 9 in the powder or granular material processing apparatus 1. Fig. 3 is a flowchart showing an example of processing in the powder or granular material processing apparatus 1.

[0052] When processing resin pellets 9 in this powder or granular material processing apparatus 1, first, the storage container 10 is placed at a first position P1. Then, the storage container 10 is placed in a first state connected to the pressure reducing mechanism 20 (step S1). That is, the suction pipe 21 of the pressure reducing mechanism 20 is connected to the connection port 14 of the storage container 10. The discharge port 13 of the storage container 10 is closed by a cap or a loop-shaped pipe.

[0053] Next, resin pellets 9 are poured into the storage container 10 (step S2). Specifically, the lid 12 of the storage container 10 is removed, and the resin pellets 9 are poured into the storage container body 11. After the pouring of the resin pellets 9 is completed, the lid 12 is attached again, and the storage container 10 is sealed.

[0054] Next, the pressure inside the storage container 10 is reduced by the decompression mechanism 20 (step S3). Specifically, the decompression pump 22 is operated to discharge the gas inside the storage container 10 to the outside through the suction pipe 21. This reduces the pressure of the gas inside the storage container 10. Then, the pressure of the gas inside the storage container 10 is maintained at a low vacuum of about minus several tens of kPa in gauge pressure for a predetermined time or more.

[0055] By reducing the pressure inside the storage container 10, the water vapor and oxygen inside the storage container 10 are discharged to the outside. This makes it possible to suppress moisture absorption and oxidation of the resin pellets 9 stored in the storage container 10. Furthermore, by reducing the pressure inside the storage container 10, the saturated water vapor pressure decreases, allowing moisture to evaporate from the surface of the resin pellets 9 stored in the storage container 10. Therefore, the amount of moisture in the resin pellets stored in the storage container 10 can be reduced. Furthermore, the effect of reducing the pressure acts uniformly on the resin pellets 9 inside the storage container 10. Therefore, the state of the resin pellets 9 before being transported to the drying container 30 can be made uniform.

[0056] Once the depressurization process is complete, the storage container 10 is then switched from the first state to the second state (step S4). Specifically, first, the depressurization mechanism 20 is removed from the connection port 14 of the storage container 10 in the first state. Next, the storage container 10 is moved from the first position P1 to the second position P2. Then, the second air supply pipe 72 of the inert gas introduction part 70 is connected to the connection port 14 of the storage container 10 in the second position P2. In addition, the transfer pipe 40 is connected to the discharge port 13 of the storage container 10 in the second position P2.

[0057] Next, the supply of nitrogen gas from the inert gas introducing part 70 is started (step S5). Specifically, by opening the on-off valve 711, nitrogen gas is introduced from the nitrogen gas generator 74 to the drying container 30. Furthermore, by opening the on-off valve 721, nitrogen gas is supplied from the nitrogen gas generator 74 to the storage container 10. As a result, the air in the storage container 10, the transfer pipe 40, the transfer hopper 34, the drying container 30, and the discharge pipe 35 is replaced with nitrogen gas.

[0058] Next, the resin pellets 9 are transported from the storage container 10 to the drying container 30 (step S6). Specifically, the transport blower 51 is operated to generate a nitrogen gas flow in the transport pipe 40. Then, the resin pellets 9 discharged from the bottom of the storage container 10 are forcefully transported through the transport pipe 40 to the transport hopper 34. Thereafter, the inlet 331 of the drying container 30 is opened, and the resin pellets 9 stored in the transport hopper 34 fall into the drying container 30.

[0059] Next, the resin pellets 9 are dried in the drying container 30 (step S7). Specifically, the drying blower 62 and the heater 63 are operated to supply hot nitrogen gas from the outlet 64 into the drying container 30. This causes moisture to move from the inside of the resin pellets 9 to the surface and evaporate, and the moisture content of the resin pellets 9 decreases to a target value.

[0060] When the drying process is completed for a predetermined time, the discharge valve 36 is opened, whereby the resin pellets 9 are discharged from the drying container 30 through the discharge pipe 35 to the injection molding machine 2 (step S8).

[0061] As described above, in step S3 of this powder or granular material processing apparatus 1, the gas pressure in the storage container 10 is reduced to suppress the influence of outside air on the resin pellets 9 before they are transferred to the drying container 30, and the state of the resin pellets 9 is made uniform. Furthermore, by reducing the gas pressure in the storage container 10, the moisture content of the resin pellets 9 before they are transferred to the drying container 30 is reduced to a certain level. Thereafter, the resin pellets 9 are dried with hot air in the drying container 30, thereby reducing the moisture content of the resin pellets 9 to a target value. This suppresses the influence of outside air and further improves the dry state of the resin pellets 9.

[0062] Furthermore, in this embodiment, the same storage container 10 is used by switching between the first state and the second state. This simplifies the configuration of the powder / granular material processing apparatus 1. If a first storage container connected to the pressure reduction mechanism 20 and a second storage container connected to the transfer pipe 40 were prepared and the resin pellets 9 were transferred from the first storage container to the second storage container, a valve would need to be installed between the first storage container and the second storage container. In this case, wear caused by the operation of the valve, which has a mechanical sliding contact portion, would easily generate particles that cause foreign matter. According to the configuration of the above embodiment, the pressure in the resin pellets 9 can be reduced while suppressing particle generation by the valve.

[0063] <3. Modifications> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0064] <3-1. First modified example> The powder or granular material processing apparatus 1 in the above embodiment includes only one storage container 10 mounted on the carriage 15. However, the powder or granular material processing apparatus 1 may include multiple storage containers 10 mounted on the carriage 15. In this case, while one storage container 10 is in the first state and undergoing depressurization treatment, the other storage container 10 can be in the second state and resin pellets 9 can be supplied to the conveying pipe 40. Furthermore, the storage container 10 in the second state after the supply of resin pellets 9 has been completed can be exchanged for the storage container 10 in the first state after the depressurization treatment has been completed. This allows the resin pellets 9 to be continuously supplied to the conveying pipe 40.

[0065] There are no particular limitations on the location where the depressurization treatment is performed on the storage container 10. That is, the first position P1 where the depressurization treatment is performed is not limited to being near the second position P2, and may be a location away from the second position P2 (for example, a separate room or building). There is no limitation on the time required for the storage container 10 to move from the first position P1 to the second position P2, as long as there is sufficient time to maintain airtightness. In this case, with regard to the control unit 80, a first control unit that controls the depressurization mechanism 20 and a second control unit that controls parts other than the depressurization mechanism 20 may be provided and operated independently.

[0066] <3-2. Second modified example> FIG. 4 is a diagram showing the configuration of a powder or granular material processing apparatus 1 according to a second modified example. The powder or granular material processing apparatus 1 of FIG. 4 further includes a heater 16 attached to the storage container 10. The heater 16 is, for example, a jacket heater attached around the storage container body 11. The heater 16 is used when the storage container 10 is in the first state. When the heater 16 is operated, the resin pellets 9 stored in the storage container 10 are heated. This allows moisture to evaporate from the resin pellets 9 in the storage container 10 not only by the action of reducing pressure but also by the action of heating.

[0067] However, if the resin pellets 9 are temporarily exposed to the outside air when switching from the first state to the second state, and if the resin pellets 9 remain at a high temperature, the outside air may cause the resin pellets 9 to be more susceptible to oxidation, or the resin pellets 9 may reabsorb moisture from the outside air as the temperature drops. For this reason, after heating with the heater 16, it is desirable to cool the resin pellets 9 to room temperature before switching the storage container 10 from the first state to the second state.

[0068] <3-3.Third modified example> Fig. 5 is a diagram showing the configuration of a powder or granular material processing apparatus 1 according to a third modified example. In powder or granular material processing apparatus 1 of Fig. 5, inert gas introduction section 70 further includes a third air supply pipe 73. The upstream end of third air supply pipe 73 is connected to nitrogen gas generator 74. The downstream end of third air supply pipe 73 is connected to storage container 10 disposed at first position P1.

[0069] An on-off valve 731 is provided in the third air supply pipe 73. When the on-off valve 731 is opened, nitrogen gas is introduced from the nitrogen gas generator 74 through the third air supply pipe 73 into the storage container 10 in the first state. This keeps the humidity and oxygen concentration of the gas in the storage container 10 low. This further suppresses moisture absorption and oxidation of the resin pellets 9 in the storage container 10. Note that the powder or granular material processing apparatus 1 may perform decompression treatment using the decompression mechanism 20 while introducing nitrogen gas from the inert gas introduction section 70 into the storage container 10 in the first state.

[0070] <3-4. Fourth Variation> In the above embodiment, the storage container 10 is moved by the cart 15 and the piping is changed over to switch the storage container 10 between the first state and the second state. However, the storage container 10 may be changed over between the first state in which it is connected to the pressure reducing mechanism 20 and the second state in which it is connected to the conveying pipe 40 by changing the piping using a valve without moving the storage container 10.

[0071] <3-5. Fifth Variation> In the above embodiment, the storage container 10 is configured with one hopper. However, the storage container 10 may be configured with two hoppers: a first hopper that performs a decompression process and a second hopper that supplies the resin pellets 9 to the conveying pipe 40. In this case, for example, the first hopper may be connected above the second hopper via a valve. Alternatively, the first hopper and the second hopper may be connected via a pipe. <3-6. Other variations>

[0072] In the above embodiment, nitrogen gas is introduced from the inert gas introduction part 70. However, the inert gas introduction part 70 may introduce other inert gases such as argon gas instead of nitrogen gas.

[0073] The powder / granular material processing apparatus of the present invention may also be used to process powder / granular materials other than resin pellets.

[0074] The detailed configuration of the powder / granular material processing apparatus may differ from that shown in the drawings of the present application. Furthermore, the elements appearing in the above-described embodiments and modifications may be combined as appropriate within the scope of not causing any contradiction. [Explanation of symbols]

[0075] 1: Powder and granular material processing equipment 2: Injection molding machine 9: Resin pellets 10: Storage container 14: Connection port 15: Cart 16: Heater 20: Pressure reduction mechanism 21:Suction tube 22: Pressure reducing pump 30: Drying container 40: Conveyor pipe 50: Circulation line for transport 60: Drying circulation line 70: Inert gas inlet 71: First air intake pipe 72: Second air intake pipe 73: Third air intake pipe 74: Nitrogen gas generator 80: Control unit P1: 1st position P2: 2nd position

Claims

1. a storage container for storing powder and granular material; a drying container for drying powder or granular material, the drying container being located downstream of the storage container in the conveying direction; a conveying pipe connecting the storage container and the drying container; an airflow generating means for generating an airflow from the storage container to the drying container within the conveying pipe; a hot air supplying means for supplying hot air to the drying container; an inert gas introduction unit that introduces an inert gas into at least the drying container; a pressure reducing mechanism that reduces the pressure of the gas in the storage container; A powder and granular material processing apparatus comprising:

2. The powder and granular material processing apparatus according to claim 1, The storage container, a first state in which the conveying pipe is disconnected from the conveying pipe and connected to the pressure reducing mechanism; a second state in which the pressure reducing mechanism is disconnected and the conveying pipe is connected; A means of switching between The powder and granular material processing apparatus further comprises:

3. The powder and granular material processing apparatus according to claim 2, A plurality of the storage containers is provided, The powder / granular material processing apparatus is capable of exchanging the storage container in the first state with the storage container in the second state.

4. The powder and granular material processing apparatus according to claim 3, The inert gas introduction unit further introduces an inert gas into the storage container in the second state.

5. The powder and granular material processing apparatus according to claim 4, Further, a circulation line connected to the conveying pipe is provided. The powder or granular material processing apparatus, wherein the inert gas introduced from the inert gas introduction part is circulated in the circulation line.

6. The powder and granular material processing apparatus according to claim 4 or 5, The storage container comprises: a connection port that is connected to the pressure reducing mechanism in the first state and that is connected to the inert gas introducing portion in the second state A powder and granular material processing apparatus having the above structure.

7. The powder / granular material processing apparatus according to any one of claims 2 to 5, a heater for heating the powder or granular material stored in the storage container in the first state; The powder and granular material processing apparatus further comprises:

8. The powder / granular material processing apparatus according to any one of claims 2 to 5, The powder / granular material processing apparatus, wherein the inert gas introduction unit further introduces an inert gas into the storage container in the first state.

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