JP2002079568A - Extrusion molding apparatus and method for manufacturing molded object using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extrusion molding apparatus capable of obtaining a molded object which can be cut into a molded product reduced in the irregularity of its cut length and has high dimensional accuracy, and a method for manufacturing the molded object using the same. SOLUTION: The extrusion molding apparatus is equipped with a die 1 having an extruding hole 3 for continuously extruding the molded product 11, a cutter 2 for cutting the molded product 11 extruded from the extruding hole 3, the flow rate control valve 17 provided in the extruding hole 3 to control the extrusion speed of the molded product 11 extruded from the extrusion hole 3, a sensor 12 for detecting the extrusion speed of the molded product 11 extruded from the extrusion hole 3 and a control means 40 for performing the on-off operation of the flow rate control valve 17 on the basis of the input signal from the sensor 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion molding apparatus capable of minimizing the variation in cutting length of a molded product and a method of manufacturing a molded article using the same.

[Prior art]

Generally, a catalyst, a catalyst carrier, an adsorbent, a drying material, a humidity control material and the like have a diameter of 2 to 10 mm and a length of 2 to 20 mm.
It is formed into a cylindrical or cylindrical shaped body, which is filled into a reactor and used for various chemical reaction processes. In order to produce such a molded article such as a catalyst, an extrusion molding method has conventionally been employed.

That is, a molded product obtained by continuously extruding a soft clay-like material such as alumina from a die is cut into small pieces to produce a molded product. At this time, if the molded product is cut with a cutting tool or the like, the cut end of the molded product is deformed and cannot be densely filled in the reactor. A problem arises that hinders the process.

For this reason, conventionally, a soft molded product immediately after being extruded from a die has been cut with a piano wire stretched between two points. That is, using a support plate in which a piano wire is stretched between two points, the support plate is rotated or reciprocated in a direction orthogonal to the extrusion direction, and the front surface of the die is extruded at a constant time interval. By crossing, the molded product immediately after extrusion is cut.

In this case, the cutting speed of the piano wire is set to a constant value, and the molded product is cut. However, since the extrusion speed of a molded product is easily changed due to a change in viscosity of a molding material, even if the extrusion speed of the molded product slightly changes, a large variation occurs in the length of the cut molded body, and as described above, Problems such as the inability to densely fill the molded body into the reactor occur.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an extrusion molding apparatus capable of reducing the variation in the cutting length of a molded article and obtaining a molded article with high dimensional accuracy, and the production of a molded article using the same. Is to provide a way.

[0007]

An extrusion molding apparatus according to the present invention for solving the above-mentioned problems comprises a die having an extrusion hole through which a molded product is continuously extruded, and cutting the molded product extruded from the extrusion hole. Cutting device, a flow control valve provided inside the extrusion hole for controlling the extrusion speed of the molded product extruded from the extrusion hole, and a sensor for detecting the extrusion speed of the molded product extruded from the extrusion hole And control means for opening and closing the flow control valve based on an input signal from the sensor.

That is, according to the present invention, since the extrusion speed of the molded product is detected by the sensor, when the extrusion speed of the molded product changes, the control means is controlled based on the input signal from the sensor. The extrusion speed of the molded product is controlled by opening and closing the flow control valve, thereby adjusting the cutting length of the molded product.

The die may have a plurality of extrusion holes. In this case, the extrusion molding device is provided with a die having a plurality of extrusion holes through which the molded product is continuously extruded, a cutting device for cutting the molded product extruded from the extrusion hole, and provided inside each extrusion hole. A flow control valve for controlling the extrusion speed of the molded product extruded from each extrusion hole, a sensor for detecting the extrusion speed of the molded product extruded from each extrusion hole, and a sensor for each extrusion hole detected by this sensor Control means for opening and closing each flow control valve based on the extrusion speed of the molded product.

[0010] The sensor is preferably a spot light source type sensor, and detects the extrusion speed of the molded article by measuring the time required for the molded article to reach the measurement point of the sensor from the extrusion hole. Thus, the extrusion speed of the molded product can be detected with high accuracy, and the cut length of the molded product can be made more uniform.

The control by the control means is, specifically,
Adjust the extrusion speed of the molded product by opening and closing the flow control valve for each extrusion hole so that the cut length of each molded product extruded from each extrusion hole approaches the average value of the cut length of the molded product Or so that the cut length of each molded product extruded from each extrusion hole approaches the set value of the cut length of the molded product
The opening and closing operation of the flow control valve is performed for each extrusion hole to adjust the extrusion speed of the molded product.

In the present invention, it is preferable to control the cutting device in addition to the control of the flow control valve in order to further reduce the variation in the cutting length of the molded product. That is, another extrusion molding apparatus of the present invention includes a die having an extrusion hole through which a molded product is continuously extruded, and a wire rod stretched between two points, in a direction orthogonal to the extrusion direction of the molded product. A cutting device for rotating or reciprocating the wire to cross the front surface of the extrusion hole to cut a molded product immediately after extrusion, and an extrusion speed of a molded product provided inside the extrusion hole and extruded from the extrusion hole. A flow control valve for controlling, a sensor for detecting an extrusion speed of a molded product extruded from the extrusion hole, a speed control for rotating or reciprocating the cutting device based on an input signal from the sensor, and the flow control And control means for performing opening and closing operations of the valve.

[0013] The die may have a plurality of extrusion holes. In this case, the extrusion molding apparatus of the present invention has a die having a plurality of extrusion holes through which a molded product is continuously extruded, and a wire rod stretched between two points, and a direction orthogonal to the extrusion direction of the molded product. A cutting device for rotating or reciprocating the wire so as to traverse the front surface of each extrusion hole and cut the molded product immediately after extrusion, and extruding a molded product provided inside each extrusion hole and extruded from the extrusion hole. A flow control valve for controlling the speed, a sensor for detecting the extrusion speed of the molded product extruded from each extrusion hole, a speed control for rotating or reciprocating the cutting device based on an input signal from the sensor, and Control means for opening and closing each flow control valve.

[0014] More specifically, the control means rotates or rotates the cutting device so that the average value of the cut length of each molded product extruded from each extrusion hole approaches the set value of the cut length of the molded product. In addition to controlling the reciprocating speed, open and close the flow control valve for each extrusion hole so that the cut length of each molded product extruded from each extrusion hole approaches the average value of the cut length of the molded product. Therefore, it is preferable to adjust the extrusion speed of the molded product. As a result, it is possible to obtain a molded product with small cutting length variation and high dimensional accuracy.

The present invention also provides a method for producing a molded article, characterized in that molded articles continuously extruded from a die are sequentially cut to a predetermined length by a cutting apparatus using the above-mentioned extrusion molding apparatus. To provide.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIGS. FIG. 1 schematically shows an extrusion molding apparatus according to this embodiment. A cutting apparatus 2 is provided on a front surface of a die 1.

The die 1 is attached to the front of the extrusion device 10 and has a plurality of extrusion holes 3 through which a molded product is continuously extruded. The cutting device 2 has two guide rollers 4
It has a piano wire 6 (wire material) stretched between the five. The piano wire 6 moves on the front surface of the extrusion hole 3 while being in contact with the top surface of the bulging portion 15 provided with the extrusion hole 3, and cuts the molded product 11 extruded from the die 1 into a predetermined length. A molded article 7 is obtained.

That is, the cutting device 2 has a disk-shaped mounting plate 9 which is integrally mounted on a rotating shaft 8 arranged parallel to the extrusion direction perpendicularly to the rotating shaft 8. Is formed so as to be spaced apart from the outer surface of the die 1, and is rotated in a direction orthogonal to the extrusion direction of the molded product 11 by rotating the rotation shaft 8 by a rotation drive unit 16 (motor).

The rotating shaft 8 is provided coaxially with the center axis of the disk-shaped die 1. Since a plurality of extrusion holes 3 are arranged concentrically in the die 1 as shown in FIG. 2, the rotation shaft 8 is rotated and the mounting plate 9 is rotated, thereby extending the front surface of the die 1. Piano wire 6
Passing across the front of. As shown in FIG. 2, two piano wires 6, 6 are stretched in the mounting plate 9 in opposite directions via a rotating shaft 8, and the respective piano wires 6, 6 Cutting is performed. In addition, the diameter of the piano wire 6 to be used may be determined in consideration of the material, diameter, and the like of the molded body, but usually 300 μm or less is appropriate.

On the other hand, inside each of the extrusion holes 3, a flow control valve 17 for controlling the extrusion speed of the molded article 11 extruded from each of the extrusion holes 3 is provided. The flow control valve 17 is a gate valve of a gate valve type. As shown in FIG.
The flow rate of the extrudate passing through the gap 19 can be controlled by adjusting the length of the gate valve 18 protruding into the gap 19. For example, the rotation driving unit 2
A so-called rack-and-pinion method in which the pinion is rotated at 0 (motor or the like) and the gate valve 18 is moved by a rack meshed with the pinion can be adopted.

A spot light source type sensor 12 is provided at a position separated from the front surface of the extrusion hole 3. The sensor 12 includes, for example, a sensor used for a purpose such as distance measurement using a laser light or a light emitting diode as a light source.
It is preferable to use a reflection-type sensor 12 (for example, a reflection-type laser sensor) including the light-receiving unit 14 for receiving the light reflected from the object, in order to reduce the size of the entire apparatus.

The mounting position of the sensor 12 is a portion that can be irradiated with spot light on the side of the side where the molded product 11 extruded from the die 1 passes, on the side separated from the die 1. Using this sensor 12, the time required for the molded article 11 to reach the measurement point of the sensor 12 from the extrusion hole 3 is measured. That is, immediately after the first cut, the molded article 11 does not exist at the measurement point (that is, the light irradiation point) of the sensor 12, and thus the sensor 12 does not detect the molded article 11, but after the first cut, the molded article 11 is newly pushed out. When the leading end of the molded article 11 reaches the measurement point, the sensor 12 detects the molded article 11, so that the time t1 from the _first detection to the second detection is known. Since the distance L from the extrusion hole 3 to the measurement point of the sensor 12 are set in advance, wherein: the extrusion velocity V of the molded product 11 is obtained from the L / t _1. The distance L from the extrusion hole 3 to the measurement point of the sensor 12 is equal to or shorter than the cutting length from the extrusion hole 3.

On the other hand, by measuring the rotational speed of the cutting device 2, the time t ₂ from when the piano wire 6 passes through the front surface of the extrusion hole 3 for the first time to when it passes for the second time can be obtained by calculation. The cutting length X of the molded article 11 is detected from the equation: V × t ₂ . The detected cutting length X is determined by the sensor 12
Is compared with the set value X ₀ by the control unit 17 which has received the input signal from the controller. When X> X ₀ , the valve stem 18 is advanced into the gap 19 to reduce the flow rate, and conversely If X <X ₀ , the valve stem 18 is withdrawn from the space 19 and X =
It is controlled such that X _0. At this time, it is preferable to control the rotation drive unit 16 of the cutting device 2 at the same time. That is, when X> X ₀ , the rotation speed of the rotation drive unit 16 is increased, and when X <X ₀ , the rotation speed of the rotation drive unit 16 is reduced.

The sensors 12 are provided for all the extrusion holes 3 as shown in FIG. That is, the sensor 12
Are installed in each of eight extrusion holes 3 concentrically arranged on the disk-shaped die 1.

FIG. 3 also shows details of the control mechanism in this embodiment. An input signal from each sensor 12 is sent to the input unit 19 in the control means 40 (sequencer) via the input switching device 18. On the other hand, the rotation speed (or rotation speed) of the rotating shaft 8 of the cutting device 2 is detected by the rotary encoder 20 and sent to the CPU 21 (central processing unit).

In the CPU 21, as shown in FIG. 4, each of the extrusion holes 3 detected by the sensor 12 disposed in each of the extrusion holes 3 is used.
The cutting length _Xn is determined from the extrusion speed of the molded article 11 at the above, and the average value _Xav of the cutting length is calculated from this. Then, the cutting length _Xn at each extrusion hole 3 is compared with the average value _Xav of the cutting lengths, and when _Xn > _Xav , the gate valve 18 of the flow control valve 17 is inserted into the gap 19. By controlling the flow rate, the flow rate is suppressed, the extrusion speed is reduced, and X = _Xav . Conversely, when X < _Xav , the gate valve 18 is retracted from the gap 19 to increase the flow rate, increase the extrusion speed, and set X =
_Xav is controlled. When X = _Xav , the flow control valve 17 remains unchanged.

These control signals are supplied to a D / A conversion unit.
22 through an inverter 23 to each flow control valve 17
Each of the provided rotary drive units 20a, 20b, 20
c,... sent to 20h, flow rate control for each extrusion hole 3
(Thus, control of the extrusion speed) is performed. For this reason, each push
The variation in the extrusion speed between the outlets 3 is reduced, and the average value X
_avVery small variation in cutting length Xn centered on
can do. The cutting length X_nIs the flat cutting length
Average value of X_avInstead of the set value X of the cutting length₀Compare with
And thus each cutting length X_nImproves dimensional accuracy of
I do.

The average value X _av is compared with the initial setting value X ₀ of the cutting length. If X _av > X ₀ , the rotational speed of the rotary drive unit 16 is reduced, and conversely, X _av If <X ₀ , the rotation speed of the rotation drive unit 16 is increased, and control is performed so that X = X ₀ . When X = X ₀ , the rotation speed of the rotation drive unit 16 does not change.

The output signal to the rotation drive unit 16 is sent from the D / A conversion unit 22 via the inverter 23 to the rotation drive unit 1.
6, and the number of rotations (and thus the rotation speed) is adjusted. As a result, the cut length can be made closer to the set value X ₀ , and the dimensional accuracy of the molded body 7 obtained by cutting the molded article 11 is improved.

On the other hand, data is recorded from the output unit 24 to the recorder 26 via the D / A converter 25. Further, the data of the cut length can be sent from the personal computer link unit 27 to the length display 28 for display.

Next, the die 1 used in this embodiment will be described. The inside diameter of the extrusion hole 3 in the die 1 is about 1 mm
10 mm, preferably about 3 mm to 6 mm. The number of extruded holes may be determined in consideration of the outer diameter of the die, the inner diameter of the extruded holes, and the like. For example, 1, 2, 4, 8, 16,
32 and the like. The shape of the extrusion hole may be, for example, a ring, a honeycomb, a clover shape, or the like in addition to a circular shape.

Specific examples of the molded product include a catalyst, a catalyst carrier, an adsorbent, a drying material, a humidity control material and the like. Further, the material of the molded body is not limited to the inorganic material, and the extrusion molding apparatus of the present invention can be applied to various plastic materials and the like. At this time, the wire used is not limited to the piano wire, but may be another metal wire or a wire made of a plastic material, a fiber material, or the like. Further, in the above-described embodiment, the mounting plate 9 is configured to rotate. However, the mounting plate 9 may be reciprocated in a direction orthogonal to the extrusion direction of the molded product. In this case, the reciprocating speed may be controlled. I just need. The piano wire 6 may be fixed between the guide rollers 4 and 5, but is preferably moved between the guide rollers 4 and 5 while being wound up continuously or intermittently. By moving the piano wire 6, breakage of the piano wire can be prevented, and a molded article can be manufactured continuously.

Another embodiment of the present invention will be described with reference to FIG. The extrusion molding apparatus shown in FIG. 5 includes a butterfly valve type flow control valve 30 which is a kind of a gate valve. This flow control valve 30 is provided behind each extrusion hole 3 of the die 1. The extruder 31 is provided with a cone 32 at the center, and directs the extrudate to each extrusion hole 3 (the flow of the extrudate is indicated by an arrow).

The flow control valve 30 includes a valve body 32 interposed between the cone 32 and the die 1, a rotating plate 33 which faces the valve body 33 and is located in the gap 19 through which the extrudate passes.
There is provided a valve rod 34 which holds the rotating plate 33 at the tip and rotates via gears 36 and 37 by driving a rotation driving unit 35 (motor or the like).

The rotation drive unit 35 receives the signal from the control means, rotates the rotary plate 33 via the valve rod 34, and controls the flow rate. That is, when the plate surface of the rotary plate 33 is orthogonal to the extrusion direction, the flow rate is minimum, and when it is parallel to the extrusion direction, the flow rate is maximum. Therefore, the flow rate can be controlled by adjusting the direction of the rotating plate 33. Others are the same as the above-mentioned embodiment.

The flow control valve according to the present invention is not limited to the above-mentioned gate valve system and butterfly valve system, and various gate valves can be adopted. For example, a screw type flow control valve 38 as shown in FIG. 6 can be adopted. The screw type flow control valve 38 controls the flow by moving forward or backward with respect to the extrusion hole 3.

[0037]

EXAMPLES The extrusion molding apparatus of the present invention will be described below with reference to examples and comparative examples.

Example A clay-like alumina catalyst molded body was extruded using the extrusion molding apparatus shown in FIGS. The die 1 used had a disk shape with eight extrusion holes 3 arranged concentrically, the surface of which was chrome-plated. The extrusion hole 3 has an inner diameter of 5 m
m. The cutting device 2 includes a piano wire 6 having a diameter of 150 μm.
Was rotated at about 90 times / second while contacting the top surface of the bulging portion 15 provided with the extrusion hole 3. Using the die 1 and the cutting device 2, the alumina catalyst molded body was extruded at an extrusion speed of about 1300 mm / min. as a result,
The cut length of the molded body 11 was 6.98 mm on average, and the standard deviation was 0.45 mm.

COMPARATIVE EXAMPLE Extrusion molding of an alumina catalyst molded body was performed in the same manner as in the example except that control using the sensor 12 was not performed. As a result, the cut length of the molded body 11 was 7.02 mm on average, and the standard deviation was 0.58 mm.

[0040]

According to the present invention, there is an effect that a variation in cut length of a molded article is reduced and a molded article having high dimensional accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an extrusion molding apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a relationship between a cutting wire and an extrusion hole of a die.

FIG. 3 is a schematic explanatory view showing a control mechanism of the extrusion molding apparatus.

FIG. 4 is a block diagram showing a control mechanism.

FIG. 5 is a schematic sectional view showing an extrusion apparatus including a flow control valve according to another embodiment of the present invention.

FIG. 6 is a schematic explanatory view showing a flow control valve according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 2 Cutting device 3 Extrusion hole 6 Piano wire (wire material) 7 Molded body 8 Rotary shaft 11 Molded product 12 Sensor 16 Rotation drive unit 17 Flow control valve 30 Flow control valve 40 Control means

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Osamu Yamanishi 5-1, Sokaicho, Niihama-shi, Ehime Sumitomo Chemical Co., Ltd. F-term (reference) 4F207 AA49 AJ02 AJ09 AP07 AR08 AR12 AR14 KA01 KA17 KL64 KL92 KM05 KM15 KM16 KW23 4G054 AA05 AB07 AB09 BD18 DA06 4G055 AA07 AB03 BB08 BB13

Claims (12)

[Claims] 1. A die having an extrusion hole through which a molded product is continuously extruded; a cutting device for cutting a molded product extruded from the extrusion hole; A flow control valve for controlling the extrusion speed of the extruded molded product; a sensor for detecting the extrusion speed of the molded product extruded from the extrusion hole; and an opening / closing operation of the flow control valve based on an input signal from the sensor. Extrusion molding device provided with control means for performing the following. 2. A die having a plurality of extrusion holes through which a molded product is continuously extruded, a cutting device for cutting the molded product extruded from the extrusion hole, and a die provided inside each of the extrusion holes. A flow control valve for controlling the extrusion speed of the molded product extruded from the extrusion hole, a sensor for detecting the extrusion speed of the molded product extruded from each extrusion hole, and the molded product detected for each extrusion hole by this sensor And a control means for opening and closing each flow control valve based on the extrusion speed of the extrusion molding apparatus. 3. The control means controls the opening and closing of the flow control valve for each extrusion hole such that the cut length of each molded product extruded from each extrusion hole approaches the average value of the cut length of the molded product. The extrusion molding apparatus according to claim 2, wherein the extrusion speed is adjusted by adjusting the extrusion speed. 4. The control means controls the opening / closing operation of the flow control valve for each extrusion hole such that the cut length of each molded product extruded from each extrusion hole approaches the set value of the cut length of the molded product. The extrusion molding apparatus according to claim 2, wherein the extrusion speed is adjusted by adjusting the extrusion speed. 5. The apparatus according to claim 1, wherein said sensor is a spot light source type sensor, and detects the extrusion speed of the molded article by measuring a time required for the molded article to reach a measurement point of the sensor from the extrusion hole. 5. The extrusion molding device according to any one of 4. 6. A die having an extrusion hole through which a molded product is continuously extruded, and a wire stretched between two points. The die is rotated or reciprocated in a direction orthogonal to the extrusion direction of the molded product. A cutting device for causing the wire to traverse the front surface of the extrusion hole and cutting the molded product immediately after extrusion; and a flow rate provided inside the extrusion hole and controlling the extrusion speed of the molded product extruded from the extrusion hole. A control valve, a sensor for detecting an extrusion speed of the molded product extruded from the extrusion hole, a speed control for rotating or reciprocating the cutting device based on an input signal from the sensor, and opening and closing of the flow control valve An extrusion molding device comprising a control means for performing operations. 7. A die having a plurality of extrusion holes through which a molded product is continuously extruded, and a wire stretched between two points, wherein the die is rotated or reciprocated in a direction orthogonal to the extrusion direction of the molded product. Then, a cutting device for cutting the molded product immediately after extrusion by causing the wire to traverse the front surface of each extrusion hole and an extrusion speed of a molded product provided inside each extrusion hole and extruded from the extrusion hole. A flow control valve for controlling, a sensor for detecting an extrusion speed of a molded product extruded from each extrusion hole, a speed control for rotating or reciprocating the cutting device based on an input signal from the sensor, and each of the flow rates An extrusion molding apparatus comprising: a control unit for performing an opening and closing operation of a control valve. 8. The cutting device rotates or reciprocates so that the average value of the cut length of each molded product extruded from each extrusion hole approaches the set value of the cut length of the molded product. Control the speed and open and close the flow control valve for each extrusion hole so that the cut length of each molded product extruded from each extrusion hole approaches the average value of the cut length of the molded product. The extrusion molding apparatus according to claim 7, wherein the extrusion speed of the product is adjusted. 9. While continuously extruding a molded product from an extrusion hole of a die, the extrusion speed of the molded product extruded from the extrusion hole is detected by a sensor, and based on an input signal from the sensor, the extrusion speed of the extrusion hole is detected. A method for manufacturing a molded article, characterized by performing opening and closing operations of a flow control valve provided inside, controlling an extrusion speed of a molded article to be extruded, and sequentially cutting the molded article to a predetermined length by a cutting device. . 10. While continuously extruding a molded product from a plurality of extrusion holes provided in a die, a sensor detects the extrusion speed of the molded product extruded from each of the extrusion holes, and detects each extrusion hole by the sensor. Based on the extruded speed of the molded product, the flow control valve provided inside each of the extrusion holes is opened and closed, and the extrusion speed of the molded product extruded from each of the extrusion holes is controlled. A method for producing a molded body, comprising sequentially cutting into a predetermined length by a cutting device. 11. While continuously extruding a molded product from an extrusion hole of a die, an extrusion speed of the molded product extruded from the extrusion hole is detected by a sensor, and based on an input signal from the sensor, the extrusion speed of the extrusion hole is detected. Controls the speed of rotation or reciprocation of the wire stretched between two points crossing the front surface,
In addition, the opening and closing operation of a flow control valve provided inside the extrusion hole is performed, the extrusion speed of the molded product extruded from the extrusion hole is controlled, and the molded product immediately after extrusion is sequentially cut into a predetermined length. A method for producing a molded article, characterized by comprising: 12. While continuously extruding a molded product from a plurality of extrusion holes provided in a die, the extrusion speed of the molded product extruded from each of the extrusion holes is detected by a sensor, and based on an input signal from the sensor. Controlling the speed of rotation or reciprocation of the wire stretched between two points crossing the front surface of the extrusion hole, and causing the flow control valve provided inside each of the extrusion holes to open and close, A method for manufacturing a molded article, characterized in that the extrusion rate of a molded article extruded from each extrusion hole is controlled, and the molded article immediately after extrusion is sequentially cut into a predetermined length.