TW202311007A - Extruder and strand die - Google Patents

Abstract

The invention provides an extrusion device capable of improving the quality of material strips and a wire drawing die. An extrusion device (1) according to one embodiment of the present invention is provided with: a cylindrical cylinder (20) that extends in one direction and has a flow path (26) through which a raw material (60) of a strand (61) flows; a wire-drawing die (40) having an inflow port (44) disposed on one end side of the cylinder and into which the raw material extruded from the cylinder flows, a discharge port (45) through which the raw material is discharged as a strand (61), and a flow path (46) through which the raw material flows from the inflow port (44) to the discharge port (45); and a screw (30) that extrudes the raw material toward the discharge port (45) by rotating about a rotation axis extending in the one direction, the cross-sectional area of the flow path (26) orthogonal to the one direction being the cross-sectional area of the flow path, and the cross-sectional area of the flow path (26) being the cross-sectional area of the flow path (26). The flow path cross-sectional area of the flow path of the wire drawing die (40), said flow path cross-sectional area being located further toward the discharge port (45) than the tip of the screw (30), is smaller than the flow path cross-sectional area of the flow path of the cylinder.

Description

Extrusion device and stranding die

The present invention relates to an extrusion device and a strand die.

Patent Document 1 discloses an extruding device having a stranding die for extruding molten resin to form strands. In the extrusion device of Patent Document 1, the flow path of the resin has a reverse tapered shape in which the diameter of the discharge port expands. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2012-232432.

In some cases, the strand die installed at the front of the extrusion unit will be fitted with a breaker plate with a fine mesh screen to filter foreign matter. At this time, in order to ensure the filtration area, the area of the particle board is expanded. As a result, the flow path of the resin has a portion whose diameter increases toward the discharge port.

In general, enlarging the diameter of the flow path reduces the flow velocity (shear velocity). Resins with strongly non-Newtonian properties have very low flow at low shear rates and tend to stagnate at the wall. This will increase the heat (thermal energy) from the heater, resulting in thermal degradation such as molecular weight reduction, and the quality of the stranded wire will be lowered.

Other subjects and novel features can be understood from the description and drawings in this specification.

An extrusion device according to one embodiment includes: a cylinder extending in one direction in a cylindrical shape, and having a flow path for the raw material of strands to flow; a stranding die disposed on one end side of the cylinder. , and has an inflow port for the raw material extruded from the cylindrical portion to flow in, a discharge port for the raw material to be discharged into the strand, and a flow path for the raw material to flow from the inflow port to the discharge port and the screw rotates around a rotating shaft extending in the aforementioned one direction, whereby the aforementioned raw material is extruded toward the aforementioned discharge port side; the cross-sectional area of the aforementioned flow path perpendicular to the aforementioned one direction is used as the cross-sectional area of the flow path, The flow path cross-sectional area of the flow path of the stranding die closer to the discharge port than the tip of the screw is smaller than the flow path cross-sectional area of the flow path of the cylindrical portion.

In one embodiment, the stranded wire mold is arranged on one end side of the cylindrical portion, the aforementioned cylindrical portion is cylindrical extending in one direction and has a flow path for the raw material of the stranded wire to flow; the aforementioned stranded wire mold has: an inlet, Inflow of the raw material extruded from the cylindrical portion by a screw rotating around a rotating shaft extending in the aforementioned one direction; a discharge port for expelling the raw material to become the stranded wire; and a flow path, It is used for the aforementioned raw material to flow from the aforementioned inlet to the aforementioned outlet; when the cross-sectional area of the aforementioned flow path perpendicular to the aforementioned one direction is used as the cross-sectional area of the flow path, the aforementioned flow path of the aforementioned stranded wire die is larger than that of the aforementioned screw. The cross-sectional area of the flow path on the side closer to the discharge port at the front end is smaller than the cross-sectional area of the flow path at the inlet.

According to the aforementioned embodiment, it is possible to provide an extruding device and a strand die capable of improving strand quality. The above objects, features and advantages of the present invention, as well as other objects, features and advantages can be fully understood from the detailed description and drawings disclosed below. The detailed description and drawings disclosed below are for illustration and should not be regarded as limiting the present invention.

For clarity of explanation, the following descriptions and drawings have been optimized, omitted and simplified. In each drawing, the same reference numerals are given to the same components, and repeated explanations are omitted as necessary.

[First Embodiment] The extrusion device of the first embodiment will be described. Fig. 1 is a side view showing an example of the structure of a pressing device according to a first embodiment. A part of Fig. 1 is shown in section. As shown in Figure 1, extrusion device 1 has driving part 10, speed reducer 11, feeder (feeder) 12, infusion pump 13, vacuum pump 14, heater 15, cylindrical part 20, through hole 23, screw rod 30, and Stranding die 40. In addition, the extrusion device 1 is provided with a thermometer and a pressure gauge for measuring the temperature and pressure of the cylindrical portion 20 and the strand die 40 at predetermined positions. The extrusion device 1 may also have a strand bath 50 and a strand cutter 51 . The extrusion device 1 extrudes a raw material 60 obtained by melting resin or the like from the strand die 40 to form strands 61 . The formed strand 61 is cooled in the strand bath 50 . After that, the strand 61 is cut with a strand cutter 51 to become a pellet 62 .

Here, an XYZ rectangular coordinate system is introduced for convenience of description of the extrusion device 1 . For example, one direction in which the cylindrical portion 20 extends is the X-axis direction, and two directions perpendicular to the X-axis direction are the Y-axis direction and the Z-axis direction. For example, the Z-axis direction is a vertical direction, and the XY plane is a horizontal plane. In addition, the +Z axis direction is upward. The end of the cylindrical portion 20 on the +X-axis direction side is referred to as one end, and the end of the cylindrical portion 20 on the −X-axis direction side is referred to as the other end. The direction in which the melted raw material 60 is extruded in the extrusion device 1 is the +X axis direction. Each configuration is described below.

[Drive unit 10, reducer 11] The drive unit 10 is provided on the other end side of the cylindrical part 20 , that is, on the −X-axis direction side of the cylindrical part 20 . The driving unit 10 can rotate the screw 30 . When the extrusion device 1 is a biaxial extrusion device, the driving unit 10 rotates the screws 31 and 32 . However, the extruding device 1 is not limited to a biaxial extruding device, and may be a multi-shaft extruding device or a uniaxial extruding device. In addition, the screws 31 and 32 are collectively referred to as the screw 30 .

The driving unit 10 is, for example, a motor. The speed reducer 11 is provided between the drive unit 10 and the screw 30 . The speed reducer 11 adjusts and transmits the rotation of the drive unit 10 to the screw 30 . Therefore, the screw 30 is rotated by the power source of the drive unit 10 regulated by the speed reducer 11 .

[feeder 12] The feeder 12 is provided above the -X axis direction side of the cylindrical portion 20 . The feeder 12 injects the raw material 60 of granulation 62 into the inside of the cylindrical part 20, for example. The raw material 60 of the granulation 62 is resin etc., for example. However, the raw material 60 is not limited to a resin alone, and may be a resin containing fibers such as glass fibers or a resin containing a pigment. The passage through which the raw material 60 flows inside the cylindrical portion 20 is called a flow path 26 . The raw material 60 supplied from the feeder 12 to the flow path 26 is pressed in the direction toward the front end on the opposite side to the base of the rotating screw 30 , that is, in the +X-axis direction. The raw material 60 is melted by the heat energy from the heater 15 attached to the cylindrical part 20 and the rotation of the screw 30 inside the cylindrical part 20 , and is changed into the melted raw material 60 . The melted raw material 60 is sent to the strand die 40 through the opening of the cylindrical portion 20 on the +X-axis direction side.

[infusion pump 13, vacuum pump 14, heater 15] The infusion pump 13 can add additives to the raw material 60 . The vacuum pump 14 can adjust the flow path inside the cylindrical part 20 to a predetermined pressure. The heater 15 heats to melt the raw material 60 .

[cylindrical part 20] The cylindrical portion 20 is a cylindrical member extending in the X-axis direction. The inside of the cylindrical part 20 has the flow path 26 through which the strand raw material 60 flows. A screw 30 is housed in the flow path 26 of the cylindrical portion 20 . When the extrusion device 1 is a biaxial extrusion device, the cylindrical part 20 includes two cylindrical parts 21 and 22 . In addition, the two cylindrical parts 21 and 22 are formed in a shape in which side parts are connected.

Fig. 2 is a cross-sectional view showing an example of the cylindrical portion 20 of the biaxial extrusion device according to the first embodiment. In FIG. 2, the screw 31, the screw 32, and the one screw 30 separated from the cylindrical part 20 are shown from the X-axis direction. As shown in FIGS. 1 and 2 , when the extrusion device 1 is a biaxial extrusion device, the cylindrical portion 20 includes two cylindrical portions 21 and 22 extending in the X-axis direction. The cylindrical part 21 and the cylindrical part 22 are arranged in the Y-axis direction, and the opposite sides of the cylindrical part 21 and the cylindrical part 22 are partially removed to be integrated. The cross-section of the cylindrical part 20 perpendicular to the X-axis direction is glasses-shaped, specifically an inverted "8" shape. However, the opposite sides of the cylindrical portion 21 and the cylindrical portion 22 are removed. Therefore, the flow path 26 of the cylindrical portion 21 and the flow path 26 of the cylindrical portion 22 are integrally formed.

Let D be the inner diameter of the cylindrical portion 21 and the cylindrical portion 22 . In addition, let the central axes of the cylindrical part 21 and the cylindrical part 22 be C1 and C2. Let the distance between the central axis C1 and the central axis C2 be W. Since the opposite sides of the cylindrical portion 21 and the cylindrical portion 22 are partially removed to be integrated, the distance W is smaller than the inner diameter D (distance W<inner diameter D). The side surface of the cylindrical portion 21 and the side surface of the cylindrical portion 22 are an intersection line L1 on the side of the +Z axis direction (intersection point P1 in the sectional view) and an intersection line L2 on the side of the -Z axis direction (intersection point P1 in the sectional view). Connect at point P2). Let the height between the intersection line L1 and the intersection line L2 be H. The height H is the height of the cylindrical portion at the center point between the central axis C1 and the central axis C2.

[Screw 30] The screw 30 rotates around a rotation axis extending in the X-axis direction. Thereby, the screw 30 extrudes the melted raw material 60 in the direction of the +X axis. The screw 30 is provided in the flow path 26 formed inside the cylindrical portion 20 . When the extrusion device 1 is a biaxial extrusion device, two screws 31 and 32 are provided. The screw 31 is provided in the flow path 26 of the cylindrical portion 21 . The screw 32 is provided in the flow path 26 of the cylindrical portion 22 . The screw 32 rotates around a rotation axis extending in the X-axis direction at a position adjacent to the screw 31 in the Y-axis direction. For example, the screw 32 is provided on the +Y-axis direction side of the screw 31 .

The rotation axis of the screw 31 is located on the central axis C1 of the cylindrical portion 21 . The rotation axis of the screw 32 is located on the central axis C2 of the cylindrical portion 22 . Seen from the X-axis direction, the screw 31 and the screw 32 are formed in an elongated shape having a length and a width. The length of the screw 30 is the same as the inner diameters of the respective cylindrical parts 21 and 22 and both are D. Let the width of the screw 30 be d. When the longitudinal direction of the screw 30 faces the Z-axis direction, it is referred to as a position in the longitudinal direction. When the width direction of the screw 30 faces the Z-axis direction, it is referred to as a lateral position. In this way, the screw rod 31 in FIG. 2 is at the position in the transverse direction, and the screw rod 32 is at the position in the longitudinal direction. Since the length of the screw 30 is the same as the length D of each of the cylindrical portions 21 and 22 , it is assumed that the screw 32 is positioned in the longitudinal direction when the screw 31 is positioned in the horizontal direction. That is, the rotation phase of the screw 31 and the rotation phase of the screw 32 are different by 90°. In addition, the width d and the shapes of the screws 31 and 32 are set so that the screws 31 and 32 can rotate in the flow paths 26 of the cylindrical parts 21 and 22 with a phase difference of 90°. Specifically, for example, α is defined as D/d, and α is the groove depth ratio of the screw 30 . In this case, the distance W and the height H satisfy Mathematical Expression 1 and Mathematical Expression 2 below.

[數學式2]

[mathematical formula 1]

[mathematical formula 2]

FIG. 3 shows an example of the cross-sectional area of the flow path of the cylindrical portion 20 of the first embodiment. As shown in FIG. 3 , assuming that the cross-sectional area of the flow path 26 perpendicular to the X-axis direction is the cross-sectional area S of the flow path, the cross-sectional area S of the flow path can be obtained by the following Mathematical Expression 3.

[mathematical formula 3]

Here, the area S1 is the sum of the fan-shaped area from the intersection point P1 to the intersection point P2 centered on the central axis C1 and the sector area from the intersection point P1 to the intersection point P2 centered on the central axis C2. The area S2 is the rectangular area enclosed by the central axis C1 , the intersection point P1 , the central axis C2 and the intersection point P2 . In this way, the area S1 and the area S2 are represented by the following Mathematical Expression 4 and Mathematical Expression 5, respectively.

[數學式5]

[mathematical formula 4]

[mathematical formula 5]

[Through hole 23, pressure and thermometer] The through hole 23 discharges volatile substances, moisture, and the like generated from the raw material 60 kneaded by the rotation of the screw 30 to the outside of the cylindrical portion 20 .

The pressure and temperature gauges are installed at predetermined positions of the cylindrical part 20, the stranding die 40, and the like. The pressure and temperature gauge can measure the pressure and temperature of the raw material 60, the melted raw material 60, the strand 61, and the like. The pressure and thermometer can also measure the pressure and temperature of gas or the like generated by kneading the raw material 60 .

[Strand wire die 40] As shown in FIG. 1 , the stranding die 40 is installed on one end side of the cylindrical portion 20 , that is, on the +X-axis direction side of the cylindrical portion 20 . The stranding die 40 is formed, for example, in a rectangular parallelepiped shape. The stranding die 40 has a front surface 47 on the +X-axis direction side and a rear surface 48 on the −X-axis direction side. The rear surface 48 is connected to one end of the cylindrical portion 20 . The rear surface 48 is formed with an inflow port 44 . A discharge port 45 is formed on the front surface 47 . Therefore, the stranding die 40 has: an inlet 44 for the molten raw material 60 extruded from the cylindrical portion 20 to flow in; an outlet 45 for discharging the molten raw material 60 into strands 61; and a flow path 46 , for the melted raw material 60 to flow from the inlet 44 to the outlet 45 .

Here, let the cross-sectional area of the flow path 46 perpendicular to the X-axis direction be the flow path cross-sectional area S0. Thus, the flow path cross-sectional area S0 of the flow path 46 of the stranding die 40 on the side closer to the discharge port 45 than the tip of the screw 30 is smaller than the flow path cross-sectional area S of the flow path 26 of the cylindrical portion 20 . That is, the following Mathematical Expression 6 is satisfied.

[mathematical formula 6]

Fig. 4 is a perspective view illustrating the stranding die 40 of the first embodiment. Fig. 5 is a partially cutaway perspective view illustrating the stranding die 40 of the first embodiment. Fig. 6 is a sectional view illustrating the stranding die 40 of the first embodiment, showing the section VI-VI in Fig. 4 . Fig. 7 is a sectional view illustrating the stranding die 40 of the first embodiment, showing the section VII-VII in Fig. 4 . As shown in FIGS. 4 to 7 , the strand die 40 includes a die holder 41 , a die head 42 and a die 43 . However, particle boards or straight rings may also be provided between the die support 41 and the die head 42 .

As mentioned above, the flow path cross-sectional area S0 of the flow path 46 of the stranding die 40 is collectively referred to as the flow path cross-sectional area S0. The flow path cross-sectional areas of the die support 41 , the die head 42 , and the die 43 are respectively referred to as a flow path cross-sectional area S41 , a flow path cross-sectional area S42 , and a flow path cross-sectional area S43 .

The flow path cross-sectional area S41 has an inflow port 44 into which the melted raw material 60 flows. Furthermore, the mold support 41 includes a part of the flow path 46 . The inlet 44 of the mold support 41 is connected to one end of the cylindrical portion 20 . Therefore, the inflow port 44 flows in the melted raw material 60 extruded from the cylindrical portion 20 . The raw material 60 flowing in from the inflow port 44 moves in the flow path 46 .

The flow path 46 of the mold support 41 may also be provided at the front end portion of the screw 30 . For example, the tip of the screw 30 may be located closer to the cylindrical portion 20 than the center point of the flow path 46 of the die holder 41 in the X-axis direction. At this time, the flow channel cross-sectional area S41 of the inlet port 44 may be the same as the flow channel cross-sectional area S of the cylindrical portion 20 . In addition, the shape of the channel cross-sectional area S41 of the inlet port 44 may be a figure-eight shape similar to the shape of the channel cross-sectional area S of the cylindrical portion 20 . The front end of the screw 30 is located in the flow path 46 of the mold support 41, thereby suppressing a decrease in the flow velocity of the molten raw material 60. Furthermore, the front end of the screw 30 is located closer to the cylindrical portion 20 than the center point of the flow path 46 of the mold support 41, thereby suppressing a decrease in the flow velocity of the raw material 60 and allowing the material to flow from the mold support 41 to the discharge port 45. The degree of change in the reduction of the flow path cross-sectional area S0 is relatively gentle.

The flow path cross-sectional area S41 of the flow path of the mold support 41 closer to the discharge port 45 than the front end of the screw 30 is preferably smaller as it is closer to the discharge port 45 (towards the +X-axis direction side). That is, the cross-sectional area S41 of the flow path is preferably gradually reduced toward the discharge port 45 side. Thereby, the reduction of the shear velocity of the wall surface of the flow path 46 can be suppressed. However, in the mold support 41 , the flow path cross-sectional area S41 may be a portion that decreases toward the +X-axis direction side, and the flow path cross-sectional area S41 may be a portion that does not change. That is, the flow path cross-sectional area A1 of the position X1 on the X-axis in the flow path 46 of the mold support 41 and the flow path cross-sectional area A2 of the position X2 closer to the +X-axis direction side than the position X1 may be A1< The part of A2 may also be the part of A1=A2. However, there will not be a portion where A1>A2.

In the mold support member 41, the cross-sectional shape of the flow path 46 may gradually change from a figure-eight shape to an oval shape toward the discharge port 45 side.

The die head 42 is provided on the side closer to the discharge port 45 than the die support 41 . Die 42 includes a portion of flow path 46 . The melted raw material 60 moves in the +X axis direction in the flow path 46 . The width in the horizontal direction of the flow path 46 of the die head 42 becomes larger toward the discharge port 45 side (+X-axis direction side). That is, the horizontal width of the flow channel 46 of the die head 42 gradually expands toward the +X-axis direction side. However, at the connection point of the die support 41 and the die head 42 , the horizontal width of the flow path 46 of the die head 42 is the same as the horizontal width of the flow path 46 of the die support 41 .

On the other hand, the width in the vertical direction of the flow path 46 of the die head 42 becomes smaller toward the discharge port 45 side (+X-axis direction side). That is, the width in the vertical direction of the flow channel 46 of the die head 42 gradually decreases toward the +X-axis direction side. However, at the connection point between the die support 41 and the die head 42 , the vertical width of the flow channel 46 of the die head 42 is the same as the vertical direction width of the flow channel 46 of the die support 41 .

The cross-sectional area S42 of the flow path of the die head 42 is preferably constant in the X-axis direction. The flow path 46 of the die head 42 expands horizontally and shrinks vertically, but the cross-sectional area S42 of the flow path is constant, so that the decrease of the shear velocity on the wall surface of the flow path 46 can be suppressed. The flow path cross-sectional area S42 of the die head 42 is equal to or smaller than the flow path cross-sectional area S41 of the die support 41 . Specifically, at the connection point between the die support 41 and the die head 42 , the flow channel cross-sectional area S42 of the die head 42 is the same as the flow channel cross-sectional area of the die support 41 . On the side closer to the +X-axis direction than the connection point, the cross-sectional area S42 of the flow path of the die head 42 may also be smaller than the cross-sectional area of the flow path of the die support 41 .

The die 43 is installed closer to the discharge port 45 than the die head 42 . The die 43 has a discharge port 45 for discharging the melted raw material 60 into strands 61 . Die 43 includes a part of flow path 46 . The discharge ports 45 are provided on the front surface 47, and a plurality of them are arranged in a row in the horizontal direction. The channel cross-sectional area S43 of the die 43 is equal to or smaller than the channel cross-sectional area S42 of the die head 42 . Specifically, at the connection point between the die head 42 and the die 43 , the flow channel cross-sectional area S43 of the die 43 is the same as the flow channel cross-sectional area of the die head 42 . However, the flow path cross-sectional area S43 of the die 43 may be smaller than the flow path cross-sectional area S42 of the die head 42 on the side in the +X-axis direction relative to the connection point.

[comparative example] Next, before explaining the effects of the present embodiment, a comparative example will be described. Then compare it with the comparative example to illustrate the effect of this embodiment. FIG. 8 is a partially cutaway perspective view illustrating a stranding die 140 of a comparative example. FIG. 9 is a cross-sectional view illustrating a strand die 140 of a comparative example. FIG. 10 is a cross-sectional view illustrating a strand die 140 of a comparative example. As shown in FIGS. 8 to 10 , the strand die 140 includes a die support 141 , a die head 142 and a die 143 . A particle board 149 may also be disposed between the mold support 141 and the mold head 142 .

The inflow port 144, the discharge port 145, the flow path 146, the front surface 147 and the rear surface 148 in the stranding die 140 of the comparative example correspond to the inflow port 44, the discharge port 45, The flow path 46 , the front surface 47 and the rear surface 48 .

In the comparative example, the flow path cross-sectional area S140 of the flow path 146 of the stranding die 140 on the side closer to the discharge port 145 than the tip of the screw 30 includes a portion larger than the flow path cross-sectional area S of the flow path of the cylindrical portion 20 . For example, the flow path cross-sectional area S141 of a part of the flow path 146 of the mold support 141 is larger than the flow path cross-sectional area S of the cylindrical portion 20 . In addition, the flow path cross-sectional area S142 of a part of the flow path 146 of the die head 142 is larger than the flow path cross-sectional area S of the cylindrical portion 20 .

Specifically, for example, in order to filter foreign matter mixed into the molten raw material 60 , a particle board 149 is generally provided between the die support member 141 and the die head 142 . Particle board 149 contains a fine mesh screen. In the comparative example, in order to ensure the filtration area of the particle board 149 , the particle board 149 and the flow path cross-sectional areas S141 , S142 before and after the particle board 149 are set larger. Therefore, the cross-sectional flow area S140 of the twisted wire die 140 includes a larger portion than the cross-sectional area S of the cylindrical portion 20 .

When the flow channel cross-sectional area S140 of the strand die 140 is larger than the flow channel cross-sectional area S of the cylindrical portion 20, the flow velocity (shear velocity) in the flow channel 146 of the strand die 140 decreases. Therefore, the fluidity of the raw material 60 is extremely reduced and stagnates on the wall surface of the flow path 146 . This may cause thermal degradation of the raw material 60 and cause a problem that the quality of the strand 61 is lowered.

Next, effects of this embodiment will be described. Generally, in the extrusion device 1 constituted by the cylindrical portion 20 and the screw 30 , the molten raw material 60 such as resin is conveyed in the axial direction by the rotation of the screw 30 . In the cylindrical part 20, due to the high shear rate generated by the rotation of the screw 30, the raw material 60 hardly stays and thermal degradation of the resin does not occur.

On the other hand, the stranding die 40 is attached to the cylindrical part 20 and the front end of the screw 30 . Therefore, the part of the twisted wire die 40 that is ahead of the front end of the screw 30 will not be subjected to the high shear rate generated by the rotation of the screw 30 . Therefore, only a pressure flow flowing purely in the axial direction is generated in the stranding die 40 . Therefore, as in the comparative example, the larger the flow path cross-sectional area S140 of the strand die 140 is, the lower the shear rate becomes. The resin fluid system with relatively low fluidity tends to stagnate on the wall of the flow channel 146 and absorb the heat generated by the heater installed in the stranding die 140, resulting in thermal degradation (decreasing molecular weight, discoloration and other quality degradation).

In contrast, in the present embodiment, the cross-sectional area S0 of the flow passage 46 of the stranding die 40 on the side closer to the discharge port 45 than the front end of the screw 30 is smaller than that of the flow passage 26 of the cylindrical portion 20. Area S. That is, the cross-sectional area S0 of the flow path closer to the discharge port 45 than the tip of the screw 30 is smaller than the cross-sectional area S of the flow path at any position. Therefore, the flow velocity (shear velocity) of the raw material 60 in the flow path 46 does not decrease. Thus, in this embodiment, the shear rate in the flow path 46 of the stranding die 40 can be increased. Therefore, it is possible to suppress stagnation of the raw material 60 on the wall surface of the flow path 46 . Thereby, thermal degradation of the raw material 60 can be suppressed, thereby improving the quality of the strand 61 . However, in this case, it sometimes happens that the pressure loss increases because the filter area of the particle board is too small. Therefore, there is an option of using a straight ring instead of using a particle board including a mesh screen by sufficiently performing management of foreign matter incorporation of the raw material 60 or the like.

[Table 1] Operating time [minutes] 60 120 180 240 300 Yellowing of comparative example 2.6 3.3 6.1 8.5 12.6 Yellowing of the first embodiment 2.2 3.4 3.2 4.0 3.9

Table 1 is an example showing the yellowing (YI; Yellow Index) of the resin when the strand 61 is formed using the strand die 140 and the strand die 40 of the comparative example and the first embodiment. For example, the following test is implemented: the stranding die 140 and the stranding die 40 shown in the comparative example and the first embodiment are installed at one end of a biaxial extrusion device with an inner diameter D=69mm of the cylindrical portion 20, and Polyamide 6 was extruded as raw material 60 at a speed of 300 kg/h. The temperature of the extruded strand 61 is about 280°C, and the temperature applied by the heater 15 of the strand die 140 and the strand die 40 is set to 280°C. In addition, in order to deliberately promote the oxidative degradation of the resin, oxygen gas is blown in at the same time as the raw material 60 of the resin is supplied to the twin-screw extruder as a condition for increasing the oxygen concentration in the twin-screw extruder.

As shown in Table 1, when using the stranding die 140 of the comparative example to form the stranding wire 61, the yellowing was 2.6, 3.3, 6.1, 8.5 and 12.6. In the strand die 140 of the comparative example, at the very beginning of extrusion, a resin that is transparent and does not contain foreign matter is ejected. However, yellowing was confirmed over time. Analyzing the results of yellowing, the yellowing system increased after three hours and then increased slowly. Thus, in the case of the comparative example, the yellowing becomes larger as the operating time becomes longer. After the experiment, the stranding die 140 was disassembled, and as a result, the accumulation of resin discolored into yellowish brown was confirmed on the wide wall surface of the flow path 146 .

On the other hand, in the case of using the stranding die 40 of the first embodiment to form strands 61, the yellowing was 2.2, 3.4, 3.2, 4.0 and 3.9. The twisted wire mold 40 of the first embodiment was not found to have yellowed resin spit out within five hours from the beginning to the end of the experiment. In this way, in the case of the first embodiment, there is almost no change in yellowing even if the operating time increases. After the experiment, the stranding mold 40 was disassembled and the results of the flow path 46 were checked. Yellowed resin accumulation was not confirmed, and smooth resin flow was confirmed even in the stranding mold 40 .

Next, the flow analysis results using the strand die 140 and the strand die 40 of the comparative example and the first embodiment will be described. FIG. 11 is a diagram showing an example of the shear velocity in the flow path 146 of the strand die 140 of the comparative example. Fig. 12 is a diagram showing an example of the shear velocity in the flow path 46 of the strand die 40 of the first embodiment. The darker parts in FIG. 11 and FIG. 12 indicate that the shear rate is lower.

As shown in FIG. 11 , in the results of the three-dimensional flow analysis in the flow path 146 under the extrusion condition of 300 kg/hour using the strand die 140 of the comparative example, the expansion of the flow path to obtain the filtration area of the particle board 149 Therefore, the portion where the shear rate of the wall surface of the flow path 146 becomes 1 [1/sec] or less can be observed. This shows that the same shear velocity of the wall surface is exhibited even if the analysis is performed by changing the particle board 149 to a straight ring, and it shows that the resin tends to stagnate in the enlarged flow path 146 .

On the other hand, as shown in FIG. 12, in the results of three-dimensional flow analysis in the flow path 46 using the strand die 40 of the first embodiment under the same extrusion conditions as in the comparative example, the wall surface of the flow path 46 was ensured. The shear rate is above 5 [1/sec] in the whole area. Therefore, it is possible to suppress the stagnation of the raw material 60 on the wall surface, and it is also possible to suppress the resin degradation phenomenon caused by the excessive heat applied.

Needless to say, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. Such changes should not be regarded as departing from the scope of technical ideas of the present invention, and all changes that are obvious to those with ordinary knowledge in the technical field are included in the scope of the following claims.

1: extrusion device 10: Drive Department 11: reducer 12: Feeder 13: Infusion pump 14: Vacuum pump 15: heater 20,21,22: Cylindrical part 23: Through hole 26: flow path 30,31,32: screw 40,140: twisted wire mold 41,141: mold support 42,142: die head 43,143: mold 44,144: Inflow port 45,145: spit outlet 46,146: flow path 47,147: front surface 48,148: back surface 50: Twisted wire bath 51: Strand cutter 60: raw material 61: twisted wire 62: Granulation 149: particle board C1, C2: central axis d: width D: inner diameter H: height L1, L2: intersecting lines S1, S2: area P1, P2: intersection point W: distance

[FIG. 1] It is a side view which exemplifies the structure of the extrusion apparatus of 1st Embodiment. [ Fig. 2 ] is a cross-sectional view showing an example of a cylindrical portion of a biaxial extrusion device according to a first embodiment. [ Fig. 3 ] shows an example of the cross-sectional area of the flow path of the cylindrical portion of the first embodiment. [ Fig. 4 ] is a perspective view showing an example of a stranding die of the first embodiment. [ Fig. 5 ] is a partially cutaway perspective view showing an example of the stranding die of the first embodiment. [Fig. 6] is a cross-sectional view illustrating the stranding die of the first embodiment, showing the cross-section of VI-VI in Fig. 4. [ Fig. 7 ] is a cross-sectional view showing an example of the stranding die of the first embodiment, showing the cross-section of VII-VII in Fig. 4 . [ Fig. 8 ] is a partially cutaway perspective view illustrating a stranding die of a comparative example. [ Fig. 9 ] is a cross-sectional view illustrating a strand die of a comparative example. [ Fig. 10 ] is a sectional view illustrating a strand die of a comparative example. [ Fig. 11 ] is a diagram showing an example of the shear velocity in the flow path of a strand die of a comparative example. [ Fig. 12 ] is a diagram showing an example of the shear velocity in the flow path of the strand die according to the first embodiment.

40: twisted wire mold

41: mold support

42: die head

43: mold

44: Inflow port

45: spit out

46: flow path

47: front surface

48: back surface

Claims (10)

An extrusion device comprising: The cylindrical part is in the shape of a cylinder extending in one direction, and has a flow path for the raw material of the stranded wire to flow; The strand die is provided on one end side of the cylindrical portion, and has an inlet for the raw material extruded from the cylindrical portion to flow in, a discharge port for the raw material to be discharged into the stranded wire, and an outlet for the aforementioned a flow path through which the raw material flows from the inlet to the outlet; and The screw rotates around a rotating shaft extending in one direction, thereby extruding the raw material toward the discharge port; Taking the cross-sectional area of the flow path perpendicular to the one direction as the cross-sectional area of the flow path, the cross-sectional area of the flow path closer to the discharge port than the front end of the screw in the flow path of the strand die is smaller than the circle. The aforementioned flow path cross-sectional area in the aforementioned flow path of the cylindrical portion. The extruding device as described in claim 1, wherein the aforementioned stranding dies include: a mold support having the aforementioned inflow port; a die head disposed on a side closer to the discharge port than the die support; and a mold, which is arranged on the side closer to the discharge port than the die head and has the discharge port; The aforementioned flow path cross-sectional area of the aforementioned mold is smaller than the aforementioned flow path cross-sectional area of the aforementioned die head; The flow path cross-sectional area of the die head is equal to or smaller than the flow path cross-sectional area of the die support. The extruding device as described in Claim 2, wherein a plurality of the aforementioned discharge ports are arranged in a horizontal direction perpendicular to the aforementioned one direction; The width in the horizontal direction of the flow path of the die is larger toward the outlet; The width in the vertical direction of the flow path of the die head becomes smaller toward the discharge port; The aforementioned cross-sectional area of the flow path of the aforementioned die is kept constant in the aforementioned one direction. The extrusion device according to claim 2 or 3, wherein the cross-sectional area of the flow path closer to the outlet than the front end of the screw in the flow path of the die support becomes smaller toward the outlet. The extrusion device according to claim 2 or 3, wherein the front end of the screw is located closer to the cylindrical portion side than the middle point of the flow path of the die support in the one direction. A stranded wire die provided on one end side of a cylindrical portion having a cylindrical shape extending in one direction and having a flow path for the raw material of the stranded wire to flow; The aforementioned stranded wire molds include: an inflow port for the inflow of the aforementioned raw material extruded from the aforementioned cylindrical portion by a screw that rotates around a rotating shaft extending in the aforementioned one direction; an outlet for expelling the aforementioned raw material to become the aforementioned stranded wire; and A flow path for the aforementioned raw material to flow from the aforementioned inlet to the aforementioned outlet; When the cross-sectional area of the aforementioned flow path perpendicular to the aforementioned one direction is used as the cross-sectional area of the flow path, the aforementioned flow path cross-sectional area of the aforementioned flow path of the aforementioned twisted wire die closer to the discharge port side than the front end of the aforementioned screw is smaller than The aforementioned flow path cross-sectional area of the aforementioned inflow port. As the stranding die described in claim 6, it has: a mold support having the aforementioned inflow port; a die head disposed on a side closer to the discharge port than the die support; and a mold, which is arranged on the side closer to the discharge port than the die head and has the discharge port; The aforementioned flow path cross-sectional area of the aforementioned mold is smaller than the aforementioned flow path cross-sectional area of the aforementioned die head; The flow path cross-sectional area of the die head is equal to or smaller than the flow path cross-sectional area of the die support. The stranding die as described in Claim 7, wherein the plurality of outlets are arranged in a horizontal direction perpendicular to the first direction; The width in the horizontal direction of the flow path of the die is larger toward the outlet; The width in the vertical direction of the flow path of the die head becomes smaller toward the discharge port; The aforementioned cross-sectional area of the flow path of the aforementioned die is kept constant in the aforementioned one direction. The twisted wire die as described in claim 7 or 8, wherein the cross-sectional area of the flow path of the flow path of the mold support member closer to the discharge port than the front end of the screw decreases toward the discharge port. The stranding die as described in claim 7 or 8, wherein the front end of the screw is located closer to the cylindrical portion than the middle point of the flow path of the die support in the one direction.

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