JP5990119B2 - Dewatering device in twin screw extruder - Google Patents

Description

  The present invention relates to a dehydrating apparatus in a twin-screw extruder, and more particularly to a novel improvement for obtaining an improvement in dewatering efficiency by using a pair of spiral grooved disks as return screw pieces in a dewatering unit screw.

Conventionally, as this type of dehydrating apparatus for a twin-screw extruder, the configuration disclosed in Patent Document 1 can be cited as FIGS. 5 to 8.
That is, FIG. 5 shows a twin-screw extruder 20, and a cylinder 21 of the twin-screw extruder 20 includes a hopper cylinder 1A, a dehydrating cylinder 1, a vent cylinder 1B, and the like from the upstream side. Is provided with a screen 3 for dehydration.

FIG. 6 is a front view of the dehydrating cylinder 1 in FIG. 5, and what is denoted by reference numeral 1 in FIG. 6 is a dehydrating cylinder used in the twin screw extruder 20 of FIG. 5. Is provided with a pair of flanges 7 having tie rod holes 8. A screen 3 is fixed to a side portion of the dehydrating cylinder 1 via a fixing member 4 and a bolt 9. As shown in FIG. 7, the screen 3 is made of a thin plate member punch metal 3 </ b> A, and has a moisture content. A small-diameter drainage hole 3Aa that can discharge the water is innumerably perforated. The screen 3 covers the drain port 6 of the dewatering cylinder 1 shown in FIG. 8, is pressed along the periphery of the drain port 6 by the fixing member 4, and is fastened and fixed by the plurality of bolts 9.
FIG. 8 is an explanatory view showing a dehydrated state of the screen 3 of FIG. 7, and moisture and synthetic resin raw material 50 are discharged from the drain hole 3Aa to the outside through the drain surface 3Ab.

Further, as shown in FIGS. 9 to 14, the screw piece 30 used in the above-described twin screw extruder 20 includes a screw or a cylinder having a cross-sectional shape having one, two, or three peaks. There is a seal ring of FIG. 15 that is concentric with the inner surface.
In general, the screw used in the twin-screw extruder 20 is a screw that combines a transport section composed of one or two or three screw pieces and two or three screw pieces or a seal ring. The kneading part (dehydration part) comprised by is comprised and comprised.
In the dehydration unit, it is necessary to apply a force to the raw material sent from the transport unit and to have a function of compressing and deforming the raw material.
When the screw rotates, the raw material is deformed by the force (shearing force) when the raw material passes through the clearance between the screw surface and the cylinder inner surface or a pair of screws, and the liquid component is compressed and separated, and the temperature of the raw material As it rises, it plasticizes and melts.
The screw used in the dewatering section, for example, a two or three screw piece 30 such as a kneading disk shown in FIGS. 11 to 13, has different shearing forces on the screw surface depending on the cross-sectional shape of each screw. Yes. The region with the strongest shear force is the peak of the cross-sectional shape where the clearance between the screw surface and the cylinder inner surface is narrow. Occupied. In the case of the seal ring of FIG. 15, the clearance is constant and the shearing force does not change on the outer periphery of the screw because it is concentric with the inner surface of the cylinder.

JP 2003-39530 A

Since the conventional twin-screw extruder is configured as described above, the following problems exist.
That is, the conventional twin-screw extruder is a device for dehydrating and extruding a screw in a dewatering section by configuring a screw piece or a seal ring of 2 to 3 strips such as a kneading disk. In the strip screw piece, since the region where the shearing force is strong is short, the liquid cannot be sufficiently squeezed from the water-containing thermoplastic resin. In addition, since the seal ring has a structure with a constant screw clearance, a constant shearing force can be maintained, but the area through which the raw material passes is limited by the length of the cylinder inner surface. Increase the speed of the raw material that passes through the clearance, the shear force becomes excessively strong, and the raw material temperature that passes through the clearance also rises. The final product has insufficient strength and poor hue, so the amount of processing has to be limited.

  The present invention has been made in order to solve the above-described conventional problems. By optimizing the screw piece of the dehydrating unit screw and improving the dehydrating capability in the dehydrating unit, the productivity is improved and the operation is performed. It can save energy.

A dehydrating apparatus in a biaxial screw extruder according to the present invention has a biaxial screw in a longitudinal cylinder formed by connecting a plurality of cylinder parts in series, and a hydrous thermoplastic resin by the dehydrating part screw of the biaxial screw. In the dehydrating apparatus in the twin screw extruder configured to squeeze the moisture of the raw material, the return screw piece provided on the dewatering unit screw has a plurality of spiral grooves on the outer periphery and partially overlaps each other when viewed from the axial direction. A pair of first and second spiral grooved discs , and one surface of the first and second spiral grooved discs extends in opposite directions along the axial direction. A biaxial portion is provided, and each axial portion of the first and second spiral grooved discs is fitted into the biaxial screw, and the first spiral grooved disc is opposed to the second axial portion and is The second helical grooved disk is configured opposed to the first shaft portion, also, the disk width along the axial direction of the spiral grooved disc, the cylinder inner diameter of the cylinder from 0.1 to 0 2D, the groove width and depth of the spiral groove is 0 . 1D (D is the inner diameter) or less, and the spiral shape of the spiral groove is such that the lead is at least three times the inner diameter of the cylinder.

Since the dehydrating apparatus in the twin screw extruder according to the present invention is configured as described above, the following effects can be obtained.
That is, a biaxial screw having a biaxial screw in a longitudinal cylinder formed by connecting a plurality of cylinder parts in series and squeezing moisture of the water-containing thermoplastic resin material by the dehydrating part screw of the biaxial screw. In the dehydrating apparatus in the extruder, the return screw piece provided in the dewatering unit screw has a plurality of spiral grooves on the outer periphery and a pair of first and second spiral grooves partially overlapping each other when viewed from the axial direction. By comprising a disk, the dewatering part screw disk of the meshing type twin screw extruder is provided with a plurality of spiral grooves, thereby improving the dewatering efficiency in the dewatering part and increasing the throughput. As a result, an effect of downsizing the extruder can be obtained. In addition, since the temperature of the raw material does not rise excessively, the energy consumption required per unit kg for production with a twin screw extruder is reduced, and there is an energy saving effect.
Furthermore, by disposing a disk screw with a plurality of spiral grooves in the dewatering part screw piece of the twin screw extruder, the throughput is increased and the dewatering capacity in the dewatering part is increased accordingly. As a result, it is possible to reduce the size of the extruder and reduce the motor size.
In addition, the first and second shaft portions are provided with the respective spiral grooved disks facing each other, so that the disk can be made compact.
The disk width along the axial direction of the spiral grooved disk is 0.1 to 0.2 D with respect to the cylinder inner diameter of the cylinder, and the groove width and depth of the spiral groove are 0 . 1D (D is the inner diameter) or less, and the spiral shape of the spiral groove is such that the lead is at least three times the inner diameter of the cylinder, so that a sufficient dewatering effect can be obtained with a small spiral groove.

It is a front view which shows the spin-drying | dehydration apparatus in the twin-screw extruder by this invention. It is explanatory drawing which shows the biaxial screw of FIG. It is a top view which shows the return screw piece of FIG. FIG. 4 is a side view of FIG. 3. It is a front view which shows the conventional biaxial screw extruder. FIG. 6 is an enlarged detailed front view showing the dewatering cylinder of FIG. 5. It is an enlarged view of the principal part of FIG. It is an expanded sectional view of the principal part of FIG. It is a perspective view which shows the conventional dehydration screw piece. It is a perspective view which shows the other form of FIG. It is a perspective view which shows the other form of FIG. It is a perspective view which shows the other form of FIG. It is a perspective view which shows the other form of FIG. It is a perspective view which shows the other form of FIG. It is a perspective view which shows the other form of FIG.

  An object of the present invention is to provide a dehydrating apparatus in a twin-screw extruder that uses a pair of spiral grooved disks as return screw pieces in a dewatering unit screw to improve dewatering efficiency.

Hereinafter, preferred embodiments of a dehydrating apparatus in a twin screw extruder according to the present invention will be described with reference to the drawings.
In addition, the same code | symbol is attached | subjected and demonstrated to a part the same as that of a prior art example, or an equivalent part.
1 is a twin screw extruder having a cylinder 21. As an example, the cylinder 21 has a hopper cylinder portion 1A and a first transport portion cylinder 22 from the upstream side toward the downstream side. The dehydrating cylinder part 1, the second transporting part cylinder 23 having the vacuum vent 8, the kneading part cylinder 24, the vacuum venting 8a and the third transporting cylinder part 25 having the discharge port 25a.

In the cylinder 21, the biaxial screw 2 shown in FIG.
The biaxial screw 2 includes a first transport unit screw 30, a dewatering unit screw 31, a second transport unit screw 32, a kneading unit screw 33, and a third transport unit screw 34 from the upstream side to the downstream side. Yes.
The dehydrating unit screw 31 is provided with a return screw piece 29 as a part on the downstream side, and the return screw piece 29 is configured as shown in FIGS. 3 and 4.

That is, the return screw piece 29 is composed of a pair of first and second spiral grooved disks 29A and 29B partially overlapping each other when viewed from the axial direction A, and the circumference of each of the spiral grooved disks 29A and 29B. A plurality of spiral grooves 40 are formed on the surface, and first and second shaft portions 41 and 42 extending in opposite directions along the axial direction A are formed on one surface of each of the spiral grooved disks 29A and 29B. Has been.

Since each of the spiral grooved disks 29A and 29B is fitted and inserted into the biaxial screw 2 of FIG. 2 via the shaft portions 41 and 42 , when viewed in plan as shown in FIG. first spiral grooved disc 29A is pair toward the second shaft portion 42, second helical grooved disks 29B on the other are disposed so as to pair toward the first shaft portion 41.

Next, the case where the extrusion process of the water-containing thermoplastic resin raw material 50 is performed in the above-described configuration will be described.
The hydrous thermoplastic resin material 50 supplied into the hopper cylinder portion 1 </ b> A of the twin-screw extruder 20 is supplied to the dehydrating cylinder portion 1 by the transport portion screw 30. The water-containing thermoplastic resin material 50 supplied to the dehydrating cylinder 1 is squeezed under high pressure generated by the shearing force of the screw, and the moisture in the thermoplastic resin material 50 is extruded from the dewatering slit 6 or the dewatering screen. It is discharged outside the machine. Here, the return screw piece 29 of the dewatering unit screw 31 is configured with the first and second spiral grooved disks 29A and 29B provided with a plurality of spiral grooves 40, so that the water-containing thermoplastic resin can be efficiently used. The dewatering can be performed while passing, and the dewatering slit 6 or the dewatering screen and the dewatering cylinder unit 1 can be provided at least one place in the extruder and can be increased depending on the form of the raw material and the moisture content. Thereafter, the mixture is uniformly kneaded by the kneading unit cylinder 24, and impurities such as moisture and volatile components in the resin are removed by the vacuum vents 8, 8a, and then transported to the discharge port 25a at the tip of the extruder by the third transport unit screw 34. A kneaded product in the form of pellets is produced from the strand by extrusion from a die (not shown) provided at the tip of the extruder.

Note that the shape and number of the spiral grooves 40 depend on the form of the water-containing thermoplastic resin raw material 50 and the moisture content, and the disk width W along the axial direction of the spiral grooved disks 29A and 29B depends on the cylinder width of the cylinder 21. 0.1 to 0.2 D with respect to the inner diameter D, the groove width W ₁ and the groove depth D ₁ of the spiral groove 40 are 0.1 D (D is the inner diameter) or less, and the spiral shape of the spiral groove 40 is a lead. It can be freely changed at least three times the inner diameter D of the cylinder 21 . The purpose of this is to dehydrate while allowing the water-containing thermoplastic resin to pass through efficiently.

Next, an example in which the present applicant experimented on the processing amount and the effect of operation using a self-made twin screw extruder 20 will be described.
The raw material used was a water-containing olefin resin (water content ≈ 30 wt%), and the twin screw extruder 20 was TEX44αII manufactured by Nippon Steel Works. The reverse screw piece of FIG. 12 was replaced with the reverse kneading of FIG. 12, the seal ring of FIG. 14 and the spiral grooved disk of FIG. 3 of the present invention, and the throughput, specific energy (Esp), outlet temperature ( Tp), the amount of dehydration was compared. As can be seen from Table 1, when the operation was carried out with the inventive product, the amount of dewatering was in a state where there was no problem, the processing amount increased compared to the conventional screw, and the values of specific energy and resin temperature decreased. As a result, it is possible to increase the processing amount, and as a result, an effect of reducing the size and energy saving of the extruder can be obtained.

  The dehydrating apparatus in the twin screw extruder according to the present invention improves the quality of the strand by obtaining a higher dewatering efficiency than before by using a spiral grooved disk for the screw piece for returning the dewatering section screw.

DESCRIPTION OF SYMBOLS 1 Dehydration cylinder part 1A Hopper cylinder part 2 Twin screw 6 Dehydration slits 8 and 8a Vacuum vent 20 Twin screw extruder 21 Cylinder 22 1st transport part cylinder 23 2nd transport part cylinder 24 Kneading part cylinder 25 3rd transport part cylinder 25a discharge part 29 return screw pieces 29A, 29B disk with spiral groove 30 first transport part screw 31 dewatering part screw 32 second transport part screw 33 kneading part screw 34 third transport part screw 40 spiral groove 41, 42 shaft part S Screw outer circumference D Inner diameter D ₁ groove depth W Disk W ₁ groove width

Claims (3)

The biaxial screw (2) has a biaxial screw (2) in a longitudinal cylinder (21) formed by connecting a plurality of cylinder parts (1A, 22, 1, 23, 24, 25) in series. In the dehydrating apparatus in the twin screw extruder in which the water content of the hydrous thermoplastic resin raw material (50) is squeezed by the dehydrating part screw (31) of
The return screw piece (29) provided on the dewatering unit screw (31) has a plurality of spiral grooves (40) on the outer periphery and a pair of first and second portions partially overlapped with each other when viewed from the axial direction (A) . second spiral grooved disc (29A, 29B) dehydrating apparatus in twin screw extruder characterized by comprising from. First and second shaft portions (41, 42) extending in opposite directions along the axial direction (A) are provided on one surface of the first and second spiral grooved disks (29A, 29B) , The shaft portions (41, 42) of the first and second spiral grooved disks (29A, 29B) are respectively fitted into the biaxial screws (2), and the first spiral grooved disk (29A) is 2. The twin screw extruder according to claim 1 , wherein the second shaft portion is opposed to the second shaft portion and the second spiral grooved disk is opposed to the first shaft portion. Dehydration equipment. The disk width (W) along the axial direction (A) of the spiral groove disk (29A, 29B) is 0.1 to 0.2D with respect to the cylinder inner diameter (D) of the cylinder (21), and the spiral groove The groove width (W ₁ ) and groove depth (D ₁ ) of (40) are 0 . 3. The method according to claim 1, wherein a spiral shape of the spiral groove is less than 1D (D is the inner diameter), and the lead is at least three times the inner diameter (D) of the cylinder (21). Dehydration device in a screw extruder.

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