TW202413055A - Spiral machine and mixing method - Google Patents

Abstract

The extruder 100 is provided with: a first ventilation filling device for pushing the material discharged from the first ventilation hole 24 formed in the barrel 20 back into the cylinder 21; and a second ventilation filling device for pushing the material discharged from the second ventilation hole 25 formed in the barrel 20 back into the cylinder 21; the screw 10 is provided with: a first mixing section 13 for mixing the material supplied from the supply port 22 into the cylinder 21; and a second mixing section 14, which is arranged at a position away from the first mixing section 13 toward the front end side of the screw 10 and has an injection rate higher than that of the first mixing section 13; the first ventilation filling device is configured such that the first ventilation hole 24 between the first mixing section 13 and the second mixing section 14 is open to the atmosphere, and the second ventilation filling device absorbs gas through the second ventilation hole 25 located closer to the front end side than the second mixing section 14 by a vacuum pump.

Description

Screw machine and mixing method

The present invention relates to a screw mill and a kneading method.

As a screw machine that mixes and melts the granular or powdered material through a screw and discharges the material, various screw machines are known (for example, Japanese Patent Publication No. 2017-77651). Japanese Patent Publication No. 2017-77651 discloses a screw machine, which includes: a cylinder, a discharge port formed at a first end; a screw that rotates in the cylinder; and a hopper that is mounted on the second end side of the cylinder and supplies the mixed material into the cylinder; a compression part is provided in the axial middle part of the screw, which compresses the conveyed mixed material and heats the mixed material; and an exhaust hole is provided in the cylinder, which is arranged on the downstream side of the compression part and communicates with the outside of the cylinder.

In the screw machine described in Japanese Patent Publication No. 2017-77651, a vent hole (exhaust hole) is provided in the cylinder to remove the gas in the cylinder. The aforementioned gas is the gas mixed in when the material is supplied or the water vapor generated by the evaporation of water contained in the material.

In order to remove the gas through the vent hole, there are two known methods: opening the vent hole to the atmosphere (so-called open atmosphere ventilation) and sucking the gas through the vent hole with a vacuum pump (so-called vacuum ventilation). In vacuum ventilation, although the amount of gas removed can be increased, if the material is in an unmelted powder form, there is a concern that the material will be sucked together with the gas.

Furthermore, in the screw machine, if the material contains a large amount of gas, there is a concern that the material will be discharged from the vent along with the gas. In order to suppress this, it is also considered to reduce the amount of material fed into the screw machine, but in this case, the amount of material discharged by the screw machine will be reduced, which may lead to a decrease in productivity.

The object of the present invention is to provide a screw machine capable of improving productivity.

According to one aspect of the present invention, a screw machine comprises: a screw, which is driven by a driving source to rotate around an axis and transport materials from the base end side to the front end side; a barrel, which forms a cylinder into which the screw is inserted; a first ventilation filling device, which pushes the material discharged from a first ventilation hole formed in the barrel back into the cylinder; and a second ventilation filling device, which pushes the material discharged from a second ventilation hole formed in the barrel back into the cylinder; the barrel has: a supply port, which is used to put material into the cylinder; and a discharge port, which is used to discharge the material in the cylinder to the outside of the barrel; the screw has: a first mixing section, which mixes and kneads the material from the supply port to the cylinder; The first vent hole opens to the cylinder between the first mixing section and the second mixing section 14 in the axial direction of the screw, and the second vent hole opens to the cylinder at the front end side of the axial direction of the screw closer to the second mixing section of the screw. The first ventilation filling device is configured so that the first ventilation hole is open to the atmosphere, and the second ventilation filling device has a vacuum pump, which is configured to suck the gas in the cylinder through the second ventilation hole by the vacuum pump.

Hereinafter, the screw machine of the embodiment of the present invention will be described with reference to the drawings. In addition, in each drawing, for the convenience of description, the scale of each structure is appropriately changed and may not be exactly as shown in the drawings.

The screw machine of this embodiment is an extruder, which is used to mix the granular or powdered materials supplied to the cylinder 21 of the barrel 20 by the screws 10a and 10b, and extrude and shape the mixed materials from the discharge port 23 of the barrel 20. Hereinafter, the screw machine of this embodiment is described as "extruder 100". In this embodiment, the material is a composite material (mixed material) in which cellulose nanofibers (CNF) and resin materials (for example, polypropylene) are mixed.

As shown in FIG. 1 and FIG. 2 , the extruder 100 includes: a pair of screws 10a and 10b; a barrel 20 having a cylinder 21 into which the pair of screws 10a and 10b are inserted; and a first motor 30 as a driving source for rotating the pair of screws 10a and 10b in the cylinder 21. Accordingly, the extruder 100 is a so-called double-shaft kneading extruder having a pair of screws 10a and 10b. Moreover, the extruder 100 is not limited to a double-shaft kneading extruder, and for example, may also be a single-shaft (single-shaft) or multi-shaft extruder having three or more shafts.

As shown in Fig. 1, the cylinder 20 is formed by connecting a plurality of cylinder units 20a in one direction. The cylinder 20 is formed as a cylindrical member extending in one direction and forming a pair of insertion holes 21a, 21b (refer to Fig. 2) along its long side direction. The pair of insertion holes 21a, 21b are connected, and the cylinder 21 is formed through the pair of insertion holes 21a, 21b.

The cylinder unit 20a at one end of the cylinder 20 in the longitudinal direction is opened to form a supply port 22 for supplying material into the cylinder 21. In the present embodiment, the material in a state of pre-mixing CNF and resin is supplied through the supply port 22. Although not shown in the figure, the material is supplied to the supply port 22 from a feeder for supplying the material through a hopper.

The barrel unit 20a at the other end of the barrel 20 in the longitudinal direction opens to the cylinder 21 to form a discharge port 23 for discharging the kneaded material generated by the melted and kneaded material. Hereinafter, in the cylinder 21, the supply port 22 side (the right side in FIG. 1 ) is also referred to as the "upstream" of the cylinder 21, and the discharge port 23 side (the left side in FIG. 1 ) is also referred to as the "downstream" of the cylinder 21. The material supplied to the cylinder 21 through the supply port 22 is transported downstream through the screws 10a and 10b, and is discharged to the outside of the barrel 20 through the discharge port 23.

And, as shown in Fig. 1 to Fig. 3, the first vent hole 24 and the second vent hole 25 are formed in the cylinder 20, which are used to discharge and remove the gas in the cylinder 21 outside the cylinder 21. And, in this embodiment, except for the first vent hole 24 and the second vent hole 25, no vent hole such as open ventilation is provided. In other words, the cylinder 20 only forms the supply port 22, the discharge port 23, the first vent hole 24, and the second vent hole 25 as holes that connect the cylinder 21 with the outside of the cylinder 20 and allow gas to pass through.

Furthermore, although not shown in the figure, a heating device for heating the cylinder 20, a cooling device for cooling the cylinder 20, and a temperature sensor for detecting the temperature of the cylinder 20 are provided on the cylinder 20.

As shown in FIG2 , a pair of screws 10a and 10b are arranged to have the same shape and extend in parallel, and are inserted into the cylinder 21 of the cylinder 20 in a mutually engaged state. The pair of screws 10a and 10b rotate in the same direction around their respective central axes (axes) via the first motor 30 (see FIG1 ) via the speed reduction unit 35. In other words, the pair of screws 10a and 10b rotate synchronously with each other. Hereinafter, the pair of screws 10a and 10b are collectively referred to as "screws 10" and the specific structure is described.

As shown in Fig. 1, the screw 10 is a shaft member provided along the longitudinal direction of the cylinder 20 from the base end connected to the first motor 30 toward the front end. The base end of the screw 10 is located upstream of the cylinder 21, and the front end is located downstream of the cylinder 21.

The screw 10 has: a first conveying part 11a, a second conveying part 11b and a third conveying part 11c, which convey the material in the cylinder 21 to the downstream; a first kneading part 13 and a second kneading part 14, which knead the material in the cylinder 21; and an end 15, which protrudes to the outside of the cylinder 20. In this embodiment, the first conveying part 11a, the first kneading part 13, the second conveying part 11b, the second kneading part 14, and the third conveying part 11c are arranged in this order from the upstream to the downstream of the cylinder 21. In addition, hereinafter, when the first conveying part 11a, the second conveying part 11b, and the third conveying part 11c are not distinguished, they are collectively referred to as the "conveying part 11".

The conveying part 11 has spiral vanes 12 (screw blades) on the outer periphery. The material supplied from the supply port 22 to the cylinder 21 is conveyed toward the first kneading part 13 on the downstream side through the first conveying part 11a of the rotating screw 10. That is, the supply port 22 is formed in the cylinder 20 in a manner facing the first conveying part 11a.

The second conveying section 11 b is provided between the first kneading section 13 and the second kneading section 14 , and conveys the material kneaded in the first kneading section 13 to the second kneading section 14 .

The third conveying unit 11 c conveys the material kneaded and melted in the second kneading unit 14 toward the discharge port 23 .

The first kneading section 13 and the second kneading section 14 are arranged to be separated from each other in the axial direction of the screw 10. The second kneading section 14 is arranged on the relatively downstream side (the front end side of the screw 10). The first kneading section 13 is composed of a plurality of disks (kneading disks) 13a arranged in the long side direction (the axial direction of the screw 10). Similarly, the second kneading section 14 is composed of a plurality of disks 14a arranged in the long side direction.

As the disk, a forward disk having a twist in the same direction as the twist of the vane 12 of the conveying portion 11, a reverse disk having a twist in the opposite direction to the twist of the vane 12 of the conveying portion 11, and a neutral disk having no twist can be used.

Like the conveying part 11, the forward feeding plate transports the material from the upstream to the downstream of the cylinder 21 (in other words, from the base end side to the front end side of the screw 10). The reverse feeding plate transports the material in the opposite direction to the conveying part 11 and the forward feeding plate. Accordingly, the function of the reverse feeding plate is to brake the flow of the material transported from the upstream to the downstream. Since the neutral plate does not rotate, it is a plate that only has the ability to knead the material and does not have the ability to transport the material.

Each pan 13a constituting the first kneading section 13 is either a forward-feeding pan or a neutral pan, and the first kneading section 13 includes at least one forward-feeding pan. In other words, the first kneading section 13 does not include a reverse-feeding pan. Furthermore, the first kneading section 13 may be constituted only by the forward-feeding pan.

Each tray 14a constituting the second kneading section 14 is any one of a forward tray, a reverse tray, and a neutral tray, and the second kneading section 14 includes at least one pair of the forward tray and the reverse tray.

The first kneading section 13 is configured to knead the transported material and has an injection rate that does not completely melt the material. The second kneading section 14 is configured to have an injection rate greater than that of the first kneading section 13 and knead the transported material to melt the material by heat transferred from the cylinder 20 or heat generated by kneading.

The so-called injection rate refers to the ratio of the volume of the material transported by the screw 10 to the volume of the space between the screw 10 and the cylinder 21. For example, the injection rate of the first kneading section 13 is the volume of the space formed between the first kneading section 13 and the cylinder 21 in the radial direction of the screw 10 (the difference between the volume of the part of the cylinder 21 that accommodates the first kneading section 13 and the volume of the first kneading section 13 as a whole) divided by the volume of the material actually contained in the space.

The end 15 of the screw 10 is connected to the first transmission part 11a on the opposite side of the first kneading part 13 in the axial direction of the screw 10. The end 15 is inserted through the cylinder unit 20a in the upstream end of the cylinder 20 and is connected to the motor shaft 31 of the first motor 30 via the speed reduction part 35 described later.

The first motor 30 is an electric motor, and its operation is controlled by a controller (not shown). The motor shaft 31 of the first motor 30 is connected to the speed reducer 35, and the rotation of the motor shaft 31 is transmitted to the pair of screws 10a and 10b via the speed reducer 35. Accordingly, the pair of screws 10a and 10b are driven and rotated by the first motor 30.

The deceleration unit 35 decelerates the rotation of the motor shaft 31 of the first motor 30 by a gear mechanism (not shown) composed of a plurality of gears, and transmits the deceleration to a pair of screws 10a and 10b. The end 15 of the screw 10 is connected to the deceleration unit 35. Since the structure of the gear mechanism of the deceleration unit 35 can adopt a known structure, detailed description and illustration are omitted.

As shown in FIG. 2 and FIG. 3 , the extruder 100 is further equipped with: a first ventilation filling device 40 for pushing the material discharged from the first ventilation hole 24 back to the cylinder 21 ; and a second ventilation filling device 41 for pushing the material discharged from the second ventilation hole 25 back to the cylinder 21 .

As shown in Fig. 1, the first vent hole 24 is provided at the center between the first kneading section 13 and the second kneading section 14 in the axial direction of the screw 10. More specifically, the first vent hole 24 is formed in the cylinder unit 20a located at the center between the first kneading section 13 and the second kneading section 14, and the center of the first vent hole 24 is substantially consistent with the center position between the first kneading section 13 and the second kneading section 14.

The second vent hole 25 is provided in the cylinder unit 20a adjacent from the downstream side relative to the cylinder unit 20a on the most downstream side accommodating the second kneading section 14. Accordingly, the second vent hole 25 is provided adjacent to the second kneading section 14 in the axial direction of the screw 10.

The difference between the first ventilation filling device 40 and the second ventilation filling device 41 is that the first ventilation filling device 40 is open to the atmosphere through the first ventilation hole 24, and the second ventilation filling device 41 is vacuum ventilated through the second ventilation hole 25, and the other structures are the same. Accordingly, the first ventilation filling device 40 is used as an example to explain the common structure of the first ventilation filling device 40 and the second ventilation filling device 41, and the second ventilation filling device 41 is labeled with the same component symbols as the first ventilation filling device 40, and the explanation is appropriately omitted.

As shown in FIG. 2 , the first ventilation filling device 40 includes: side screws 45a and 45b as a pair of screw components; a housing 47 forming a side cylinder 47a into which the side screws 45a and 45b are inserted; and a second motor 48 as a driving source for rotating the pair of side screws 45a and 45b around their axes.

Although detailed illustration is omitted, a pair of side screws 45a, 45b are provided to have the same shape and extend in parallel, and are arranged in the axial direction of the screw 10. The pair of side screws 45a, 45b are inserted into the side cylinder 47a of the housing 47 in a state of being engaged with each other. The pair of side screws 45a, 45b rotate in the same direction around their respective center axes (axes) by the second motor 48. That is, the pair of side screws 45a, 45b rotate synchronously with each other. Hereinafter, the pair of side screws 45a, 45b will be collectively referred to as "side screws 45" and the specific structure will be described.

As shown in Fig. 2, the side screw 45 is a shaft member having a base end connected to the second motor 48 and a front end inserted into the first vent hole 24 of the cylinder 20. The side screw 45 is provided on a substantially same horizontal plane as the screw 10 and substantially perpendicular to the screw 10.

Like the screw 10, a spiral vane 46 (screw blade) is provided on the outer periphery of the side screw 45. The vane 46 is provided in a local area in the axial direction of the side screw 45. Moreover, the present invention is not limited thereto, and the vane 46 may be provided to spread over the entire axial direction of the side screw 45.

The second motor 48 rotates the side screw 45, and the material discharged from the first vent hole 24 to the outside of the cylinder 21 is pushed back into the cylinder 21 by the side screw 45. In other words, the side screw 45 can move the material toward the cylinder 21 by rotating. The second motor 48 is an electric motor, and its operation is controlled by a controller (not shown).

The housing 47 is mounted on the cylinder 20 by means of bolts (not shown) covering the first vent hole 24. The housing 47 is in contact with the cylinder 20 (metal contact), thereby sealing the housing 47 and the cylinder 20 in a manner that does not cause material to flow out. Although not shown, the side cylinder 47a of the housing 47 is formed by inserting a pair of side screws 45a and 45b into insertion holes that are connected to each other, as in the cylinder 21 of the cylinder 20. When the housing 47 is mounted on the cylinder 20, the side cylinder 47a of the housing 47 is connected to the first vent hole 24. A vent 47b connected to the side cylinder 47a is formed in the housing 47. The vent 47b is a hole open to the atmosphere. The vent 47 b is formed to face the portion of the side screw 45 where the vane 46 is not formed.

In the first ventilation filling device 40, when L1 is the length from the end of the barrel unit 20a on the base end side of the screw 10 to the center position O1 of the first ventilation filling device 40 in the axial direction of the screw 10, and D is the diameter of the screw 10, L1/D is set to be greater than 21 and less than 32. The center position O1 of the first ventilation filling device 40 in the axial direction of the screw 10 is equivalent to the central position of the central axes of a pair of parallel side screws 45a and 45b of the first ventilation filling device 40 along the axial direction of the screw 10. In the present embodiment, the center position O1 of the first ventilation filling device 40 is roughly consistent with the center position of the first ventilation hole 24. Furthermore, when the first ventilation filling device 40 is a single-axis device, the center position of the first ventilation filling device 40 is equivalent to the center position of the center axis of the side screw 45. When there are multiple axes of three or more axes, the center position of the first ventilation filling device 40 is equivalent to the center position of the double axes of the side screw 45 with the longest distance between the axes. The center position is also the same for the second ventilation filling device 41 described later. In addition, the diameter D of the screw 10 can be, for example, φ48 (mm).

As shown in FIG. 3 , the second ventilation filling device 41 has a vacuum pump 49 for sucking gas in addition to the structure of the first ventilation filling device 40 .

The vent 47b formed in the housing 47 of the second ventilation filling device 41 is not open to the atmosphere, but is connected to the vacuum pump 49 via a pipe (not shown). Accordingly, the second vent hole 25 of the cylinder 20 is also not open to the atmosphere, but is connected to the vacuum pump 49.

The vacuum pump 49 is driven by a driving source (not shown) and sucks gas from the side cylinder 47a in the housing 47 through the vent 47b of the housing 47 of the second ventilation charging device 41. Accordingly, the vacuum pump 49 sucks gas from the cylinder 21 of the cylinder 20 through the second vent hole 25 connected to the side cylinder 47a in the housing 47. Since the vacuum pump 49 can adopt a known structure, detailed description and illustration are omitted.

In the second ventilation filling device 41, when L2 is the length along the axial direction of the screw 10 from the end of the barrel 20 on the front end side of the screw 10 to the center position O2 of the second ventilation filling device 41 in the axial direction of the screw 10, L2/D is set to be greater than 5 and less than 11. The center position O2 of the second ventilation filling device 41 in the axial direction of the screw 10 is equivalent to the central position of the central axes of a pair of parallel side screws 45a and 45b of the second ventilation filling device 41 along the axial direction of the screw 10. Moreover, in this embodiment, the center position of the second ventilation filling device 41 is roughly consistent with the center position of the second ventilation hole 25.

Next, the function of the extruder 100 will be described.

After the extruder 100 is operated, the first motor 30 controls the pair of screws 10 to rotate in the same direction at the same speed. In addition, while the side screws 45 of the first ventilation filling device 40 and the second ventilation filling device 41 are rotated by the second motor 48, the vacuum pump 49 of the second ventilation filling device 41 is operated.

The material supplied into the cylinder 21 through the supply port 22 is conveyed downstream in the longitudinal direction by the first conveying portion 11 a of the screw 10 .

The material transported downstream by the first conveying section 11a is kneaded in the first kneading section 13. The injection rate of the first kneading section 13 is lower than that of the second kneading section 14, and is set to a level that does not completely melt the material. Therefore, the material introduced to the first kneading section 13 is heated by kneading in the first kneading section 13, and most (at least a part) of it remains in an unmelted solid (powder) state.

The material kneaded in the first kneading section 13 is conveyed to the downstream side of the second kneading section 14 by the second conveying section 11b.

The material is kneaded and completely melted in the second kneading section 14. The material melted in the second kneading section 14 is conveyed toward the discharge port 23 by the third conveying section 11c, and is discharged through the discharge port 23.

Here, as the material is supplied into the cylinder through the supply port, gas (air) is mixed into the cylinder together with the material. In addition, the moisture contained in the material is vaporized by heating. Therefore, if the material contains gas, it becomes impossible to supply the material into the cylinder. In other words, the air returning from the cylinder hinders the supply of the material.

In particular, there is a concern that CNF agglomeration may occur when the water content is low, and the water content of the composite material of CNF and resin is relatively high. As the material used in the extruder 100 of this embodiment, for example, it is assumed that the mixing ratio of CNF is 50-70% and the water content of the material is 3-7%. In this case, the amount of gas in the material is particularly large.

Therefore, in the present embodiment, the gas in the material is removed through the first vent hole 24 and the second vent hole 25 formed in the cylinder 20 .

However, when the material contains a large amount of gas, there is a concern that the material and the gas may be discharged from the first vent hole 24 and the second vent hole 25, that is, a phenomenon called vent up or flake up occurs. Therefore, in this embodiment, a first ventilation filling device 40 and a second ventilation filling device 41 are respectively provided at the first vent hole 24 and the second vent hole 25. The first ventilation filling device 40 and the second ventilation filling device 41 rotate by the side screw 45 to push the material discharged from the first vent hole 24 and the second vent hole 25 to the outside of the cylinder 21 back into the cylinder 21. On the other hand, the gas in the cylinder 21 is guided to the vent 47b through the interlocking gap between the side screws 45 or the small gap between the side screws 45 and the side cylinder 47a, and is discharged outside the cylinder 21. Therefore, even if the material has a high water content, it can be prevented from bubbling from the first vent 24 and the second vent 25, and the gas in the cylinder 21 can be effectively removed.

Furthermore, if the material contains a large amount of moisture (or even gas), it becomes difficult for the gas contained in the material to pass through the mixing section if the material supplied from the supply port is configured to be fully melted in the first mixing section. In other words, if the injection rate of the first mixing section is set relatively high in order to completely melt the material, it becomes difficult for the moisture (water vapor) in the material to pass through the first mixing section. As a result, there is a concern that the gas or water vapor contained in the material flows back toward the supply port and hinders the supply of the material from the supply port to the cylinder.

In this embodiment, the injection rate of the first kneading section 13 is lower than that of the second kneading section 14, and the material is not completely melted. Therefore, the water vapor in the material is easily guided to the first vent hole 24 through the first kneading section 13, and the backflow of the water vapor to the supply port 22 is suppressed.

Furthermore, since the material is not completely melted in the first kneading section 13, the first ventilation filling device 40 is configured to perform open ventilation to the atmosphere, rather than vacuum ventilation. Since the material is not completely melted in the first kneading section 13, it is transported by the second conveying section 11b in a solid (powder) state. In the case of vacuum ventilation through the first vent hole 24, there is a concern that the solid material is sucked together with the gas by the vacuum pump 49. Accordingly, by configuring the first vent hole 24 to perform open ventilation to the atmosphere, the discharge of the material through the first vent hole 24 can be suppressed, and the gas can be removed.

Furthermore, since the pressure near the first kneading section 13 and the second kneading section 14 becomes higher than that in other parts due to kneading, if the first vent hole 24 is provided near the first kneading section 13 and the second kneading section 14, there is a concern that the material may be discharged from the first vent hole 24 together with the gas due to pressure. Therefore, by providing the first vent hole 24 at the approximate center of the first kneading section 13 and the second kneading section 14 in the axial direction of the screw 10, it is possible to suppress the material from being discharged from the first vent hole 24 due to the pressure of kneading.

Since the material is completely melted in the second kneading section 14, it is difficult to absorb the melted material even if vacuum ventilation is performed in the second vent hole 25. Accordingly, the gas in the cylinder 21 can be effectively removed by using the second vent hole 25 as a structure for performing vacuum ventilation.

Furthermore, the first vent hole 24 may be located between the first kneading section 13 and the second kneading section 14 at least in the axial direction of the screw 10, and at least a portion thereof may face the cylinder 21 between the first kneading section 13 and the second kneading section 14. Furthermore, at least a portion of the second vent hole 25 may face the cylinder 21 downstream of the second kneading section 14.

Furthermore, since the second vent hole 25 is disposed at a position adjacent to the second kneading section 14 from the downstream side in the axial direction, it faces the material just passing through the second kneading section 14. Therefore, the gas is easily discharged through the second vent hole 25 due to the pressure of kneading in the second kneading section 14, and the gas can be effectively removed.

Furthermore, since the extruder 100 can fully remove the gas in the cylinder 21 through the first vent hole 24 provided with the first vent filling device 40 and the second vent hole 25 provided with the second vent filling device 41, no vent holes other than these are formed in the cylinder 20. Although increasing the number of vent holes is also considered in order to remove the gas more effectively, if the number of vent holes is increased, the total length of the cylinder 20 becomes longer, and accordingly, the material transportation distance also becomes longer. As the material transportation distance becomes longer, the thermal effect on the resin material contained in the material becomes larger, and there is a concern that the quality is affected. In the present embodiment, by not providing ventilation holes other than the first ventilation hole 24 and the second ventilation hole 25, the size of the cylinder 20 is suppressed from being enlarged, the gas in the cylinder 21 can be removed, and the thermal influence on the material can be suppressed.

The following describes the effects of this embodiment.

The extruder 100 includes: a screw 10, which is driven by a first motor 30 to rotate around an axis and transport the material from the base end side to the front end side; a barrel 20, which forms a cylinder 21 into which the screw 10 is inserted; a first ventilation filling device 40, which pushes the material discharged from a first ventilation hole 24 formed in the barrel 20 back into the cylinder 21; and a second ventilation filling device 41, which pushes the material discharged from a second ventilation hole 25 formed in the barrel 20 back into the cylinder 21; the barrel 20 has: a supply port 22, which is used to put the material into the cylinder 21; and a discharge port 23, which is used to discharge the material in the cylinder 21 to the outside of the barrel 20; the screw 10 has: a first kneading section 13, which kneads the material discharged from the supply port 24. 2 is supplied into the cylinder 21; and the second kneading section 14 is arranged at a position away from the first kneading section 13 toward the front end side of the screw 10, and the injection rate is higher than that of the first kneading section 13; the first vent hole 24 is opened to the cylinder 21 between the first kneading section 13 and the second kneading section 14 in the axial direction of the screw 10, and the second vent hole 25 is opened to the cylinder 21 at the front end side of the axial direction of the screw 10 than the second kneading section 14 of the screw 10, the first ventilation filling device 40 is configured so that the first ventilation hole 24 is open to the atmosphere, and the second ventilation filling device 41 has a vacuum pump 49, and is configured so that the gas in the cylinder 21 is sucked through the second ventilation hole 25 by the vacuum pump 49.

Furthermore, the kneading method of this embodiment kneads the material in which the cellulose nanofibers and the resin material are mixed by the extruder 100. The kneading method of this embodiment includes: inserting a screw 10 that transports the material toward the front end side in the axial direction by rotating into the cylinder 21 of the barrel 20, and supplying the material through the supply port 22 provided in the barrel 20 relative to the cylinder 21 of the barrel 20; guiding the material supplied from the supply port 22 to the first kneading section 13 of the screw 10, and kneading the material through the first kneading section 13; guiding the material kneaded by the first kneading section 13 to the second kneading section 14 of the screw 10, and kneading the material through the second kneading section 14; discharging the material kneaded by the second kneading section 14 through the discharge port 23 formed in the barrel 20; and discharging the material through the first ventilation port 23 opened to the cylinder 21 between the first kneading section 13 and the second kneading section 14 in the axial direction of the screw 10. hole 24, a process of pushing the material discharged from the first vent hole 24 back into the cylinder 21 and removing the gas in the cylinder 21 by means of the first vent filling device 40; and a process of pushing the material discharged from the second vent hole 25 back into the cylinder 21 and removing the gas in the cylinder 21 by means of the second vent filling device 41 through a second vent hole 25 opened toward the cylinder 21 at the front end side of the axial direction of the screw 10 rather than the second mixing section 14 of the screw 10; in the process of removing the gas through the first vent hole 24, the first vent filling device 40 opens the first vent hole 24 to the atmosphere to remove the gas, and in the process of removing the gas through the second vent hole 25, the gas is sucked through the second vent hole 25 by means of the vacuum pump 49 of the second vent filling device 41 to remove the gas.

According to these structures, even if there is a powdery material between the first kneading section 13 and the second kneading section 14 that has not reached the second kneading section 14, the first vent hole 24 can be ventilated to the atmosphere instead of being ventilated by vacuum, so that the powdery material can be avoided from being sucked by the vacuum pump 49. Furthermore, the first vent hole 24 and the second vent hole 25 are respectively suppressed from discharging the material by the first side filling device and the second side filling device. According to this, since the gas backflow to the supply port 22 is suppressed, and the material is also suppressed from being discharged from the first vent hole 24 and the second vent hole 25, the productivity of the screw machine can be improved.

Furthermore, in the extruder 100 , the injection rate of the first kneading section 13 is lower than that of the second kneading section 14 .

Furthermore, in the extruder 100, the screw 10 further comprises: a conveying section 11, a spiral-shaped vane 12 formed on the outer periphery, and conveying the material toward the front end side; a plurality of disks 13a constituting the first kneading section 13, including a forward conveying disk having a twist in the same direction as the vane 12 of the conveying section 11, and not including a reverse conveying disk having a twist in the opposite direction to the vane 12 of the conveying section 11; and a plurality of disks 14a constituting the second kneading section 14, including both a forward conveying disk and a reverse conveying disk.

According to these structures, since the injection rate of the first kneading section 13 is lower than that of the second kneading section 14, the melting of the material in the first kneading section 13 is suppressed, and the backflow of the gas toward the supply port 22 is suppressed.

Furthermore, in the extruder 100, the barrel 20 is composed of a plurality of barrel units 20a connected along the axial direction of the screw 10, the first vent hole 24 is formed in the barrel unit 20a located in the center between the first mixing section 13 and the second mixing section 14, and the second vent hole 25 is formed in the barrel unit 20a adjacent to the barrel unit 20a accommodating the second mixing section 14 on the front end side of the screw 10.

Furthermore, in the extruder 100, when L1 is the length along the axial direction of the screw 10 from the end of the barrel 20 on the base end side of the screw 10 to the center position O1 of the first ventilation filling device 40 in the axial direction of the screw 10, and D is the diameter of the screw 10, L1/D is greater than 21 and less than 32, and when L2 is the length along the axial direction of the screw 10 from the end of the barrel 20 on the front end side of the screw 10 to the center position O2 of the second ventilation filling device 41 in the axial direction of the screw 10, and D is the diameter of the screw 10, L2/D is greater than 5 and less than 11.

In these structures, since the first vent hole 24 is provided at the center between the first kneading section 13 and the second kneading section 14, it is possible to suppress the unmelted material from being discharged from the first vent hole 24 due to the kneading pressure. Furthermore, since the second vent hole 25 is provided adjacent to the downstream side of the second kneading section 14, it is possible to more effectively discharge only the gas in the material by the kneading pressure. Accordingly, in these structures, it is possible to suppress the discharge of the material and effectively remove the gas in the material.

Next, the variants of this embodiment are described. The following variants are also within the scope of the present invention, and can be combined with the structures of the above-mentioned embodiment, or can be combined with each other. In addition, in each variant, the same component symbols are marked for the same structures as the above-mentioned embodiment, and the description is omitted.

In the above embodiment, the extruder 100 is used for kneading and melting the composite material of CNF and resin material containing a high moisture content. The material that can use the extruder 100 is not limited thereto, and although it can be applied to various materials, as described above, it is particularly useful for materials with a high moisture content.

Furthermore, in the above-mentioned embodiment, the material is a mixture of CNF and resin material, and the material is supplied from one feeder to the cylinder 21 of the barrel 20 through the supply port 22. In contrast, a feeder for supplying CNF to the hopper of the supply port 22 and a feeder for supplying the resin material to the hopper of the supply port 22 may be separately provided, and CNF and the resin material may be mixed in the hopper of the supply port 22 or in the cylinder 21.

Furthermore, in the above-mentioned embodiment, the first ventilation filling device 40 and the second ventilation filling device 41 have the same structure except for the structure of the vacuum pump 49. In this regard, the first ventilation filling device 40 and the second ventilation filling device 41 may not have the same structure. For example, the side screws 45 of the first ventilation filling device 40 and the second ventilation filling device 41 may not have the same shape.

The side screw 45 improves the ability to push back the material (carrying ability) by shortening the pitch of the outer periphery of the vanes 46 or lengthening the length (vane length) of the portion where the vanes 46 are provided. The pitch or length of the vanes 46 of the side screw 45 can be arbitrarily set according to the properties of the material, etc. In addition, the vent 47b can also be provided at a position facing the vanes 46 of the side screw 45.

Furthermore, the side screws 45 of the first ventilation filling device 40 and the second ventilation filling device 41 can also be operated under different operating conditions (rotation speeds). By increasing the rotation speed of the side screws 45, the ability to push back the material can be improved.

Furthermore, although the first ventilation filling device 40 and the second ventilation filling device 41 are double-axis devices having a pair of side screws 45a and 45b respectively, they may also be multi-axis devices having one axis or more than three axes, as in the extruder 100.

Although the embodiments of the present invention have been described above, the embodiments described above merely represent a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific structures of the embodiments described above.

10, 10a, 10b: screw 11: transmission part 11a: first transmission part 11b: second transmission part 11c: third transmission part 12: vane 13: first mixing part 13a: disk 14: second mixing part 14a: disk 15: end part 20: cylinder 20a: cylinder unit 21: cylinder 21a, 21b: insertion hole 22: supply port 23: discharge port 24: first ventilation hole 25: second ventilation hole 30: first motor 31: motor shaft 35: speed reduction part 40: first ventilation filling device 41: second ventilation filling device 45, 45a, 45b: side screw 46: Feather 47: Shell 47a: Side cylinder 47b: Vent 48: Second motor 49: Vacuum pump 100: Extruder D: Diameter L1, L2: Length O1, O2: Center position

FIG1 is a cross-sectional view showing the overall structure of an extruder according to an embodiment of the present invention. FIG2 is a cross-sectional view showing an extruder according to an embodiment of the present invention, and is a cross-sectional view taken along the II-II line in FIG1. FIG3 is a cross-sectional view showing an extruder according to an embodiment of the present invention, and is a cross-sectional view taken along the III-III line in FIG1.

10: Screw

11:Transmission Department

11a: First transmission unit

11b: Second transmission unit

11c: The third transmission unit

12: Feathers

13: First Mixing Section

13a: Plate

14: Second Mixing Section

14a: Plate

15: End

20: Cylinder parts

20a: Cylinder unit

21: Cylinder

22: Supply port

23: Spit it out

24: First vent hole

25: Second vent hole

30: First Motor

31: Motor shaft

35: Speed reduction unit

100: Extruder

D: Diameter

L1, L2: length

O1, O2: center position

Claims (9)

A screw machine, the screw machine having: A screw, which is driven by a driving source to rotate around an axis and transports a material from a base end side to a front end side; A barrel, which forms a cylinder into which the screw is inserted; A first ventilation filling device, which pushes the material to be discharged from a first ventilation hole formed in the barrel back into the cylinder; and A second ventilation filling device, which pushes the material to be discharged from a second ventilation hole formed in the barrel back into the cylinder; The barrel has: A supply port, which is used to put the material into the cylinder; and A discharge port, which is used to discharge the material in the cylinder out of the barrel; The screw has: A first kneading section, which mixes the material supplied from the supply port into the cylinder; and The second kneading section is arranged at a position away from the first kneading section toward the front end side of the screw; The first vent hole opens toward the cylinder between the first kneading section and the second kneading section in the axial direction of the screw, The second vent hole opens toward the cylinder at the front end side of the axial direction of the screw closer to the second kneading section of the screw, The first ventilation filling device is configured to open the first ventilation hole to the atmosphere, The second ventilation filling device has a vacuum pump, and is configured to suck the gas in the cylinder through the second ventilation hole by the vacuum pump. The screw mill as described in claim 1, wherein the injection rate of the first mixing section is lower than that of the second mixing section. The screw machine as described in claim 2, wherein, the screw further comprises: a conveying section having spiral vanes formed on the outer periphery and conveying the material toward the front end side; the plurality of disks constituting the first mixing section include a forward conveying disk having a twist in the same direction as the twist of the vanes of the conveying section, and do not include a reverse conveying disk having a twist in the opposite direction to the vanes of the conveying section, the plurality of disks constituting the second mixing section include both the forward conveying disk and the reverse conveying disk. The screw machine as described in claim 1, wherein, Let L1 be the length from the end of the barrel at the base end of the screw to the center position of the first ventilation filling device along the axis direction of the screw, and let D be the diameter of the screw, L1/D is greater than 21 and less than 32; Let L2 be the length from the end of the barrel at the front end of the screw to the center position O2 of the second ventilation filling device along the axis direction of the screw, and let D be the diameter of the screw, L2/D is greater than 5 and less than 11. The screw machine as described in claim 1, wherein a mixed material of cellulose nanofibers and resin material is kneaded as the aforementioned material and discharged. A kneading method, wherein the kneading method kneads a material in which cellulose nanofibers and a resin material have been mixed by a screw machine, wherein the kneading method comprises: Inserting a screw that transports the material toward the front end side of the axial direction by rotation into a cylinder of a barrel, and supplying the material through a supply port provided in the barrel by the cylinder relative to the barrel; Guide the material supplied from the supply port to a first kneading section of the screw, and knead the material by the first kneading section; Guide the material kneaded by the first kneading section to a second kneading section of the screw, and knead the material by the second kneading section; Discharge the material kneaded by the second kneading section through a discharge port formed in the barrel; The process of pushing the material discharged from the first vent hole back into the cylinder through the first vent filling device through the first vent hole opening toward the cylinder between the first kneading section and the second kneading section in the axial direction of the screw, and removing the gas in the cylinder; and The process of pushing the material discharged from the second vent hole back into the cylinder through the second vent hole opening toward the cylinder on the front end side of the axial direction of the screw than the second kneading section of the screw, and removing the gas in the cylinder through the second vent filling device; In the process of removing the gas through the first vent hole, the first vent filling device opens the first vent hole to the atmosphere to remove the gas, In the process of removing gas through the aforementioned second vent hole, the gas is removed by sucking gas through the aforementioned second vent hole using the vacuum pump of the aforementioned second vent filling device. The kneading method as described in claim 6, wherein the injection rate of the first kneading section is lower than that of the second kneading section. The kneading method as described in claim 7, wherein, the screw has: a conveying section, which forms a spiral blade on the outer periphery and transports the material toward the front end side; the plurality of disks constituting the first kneading section includes a forward conveying disk that is twisted in the same direction as the blade of the conveying section, and does not include a reverse conveying disk that is twisted in the opposite direction to the blade of the conveying section, the plurality of disks constituting the second kneading section includes both the forward conveying disk and the reverse conveying disk. The kneading method as described in claim 6, wherein, Let L1 be the length from the end of the barrel at the base end of the screw to the center position of the first ventilation filling device along the axis direction of the screw, and let D be the diameter of the screw, L1/D is greater than 21 and less than 32; Let L2 be the length from the end of the barrel at the front end of the screw to the center position O2 of the second ventilation filling device along the axis direction of the screw, and let D be the diameter of the screw, L2/D is greater than 5 and less than 11.