JP2002283440A - Method and apparatus for manufacturing bar-like material made of synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a resin scrap by eliminating a necessity of a complicated maintenance. SOLUTION: An apparatus for manufacturing a bar-like material made of a synthetic resin continuously extrudes a thermoplastic resin to the outer periphery of the continuous bar-like material 12 made of a steel wire running at a predetermined speed, a fiber-reinforced synthetic resin or the like by extruders 16, 18 to cover the material 12 with the resin, and then cools to solidify the resin to form a coating layer thereon. The apparatus comprises an outer diameter measuring instrument 20 installed at the downstream side of the extruder 18 to measure the manufacturing outer diameter value of the bar-like material 10 made of the synthetic resin after cooling to be solidified and having a controller 22. The controller 22 controls the extruded amount of the synthetic resin of the extruder 18 based on the manufacturing outer diameter value detected by the instrument 20, previously sets a deviation value becoming an allowable range for the designed outer diameter of the material 10 intended to be manufactured, and controls so that when a plurality of the manufactured outer diameters obtained by the instrument 20 even once satisfies the value within the deviation value, the extruded amount of the extruder 18 is maintained as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin rod formed by applying a thermoplastic resin coating to a steel wire or a fiber reinforced synthetic resin rod, for example, a tensile strength wire for a helical spacer for supporting an optical fiber. The present invention relates to a method and an apparatus for manufacturing a rod-shaped object to be manufactured.

[0002]

2. Description of the Related Art As a method and an apparatus for manufacturing a synthetic resin rod, a technique proposed in, for example, Japanese Patent Application Laid-Open No. Hei 5-4272 is known. In the method of manufacturing a synthetic resin rod-shaped material disclosed in this publication, after the thermoplastic resin is continuously extruded and coated on the outer periphery of a continuous rod-shaped body running at a predetermined speed, a molten thermoplastic resin is coated. The basic configuration is that a coating layer is formed by cooling and solidifying, and this coating layer is inserted into a diameter adjuster having a predetermined inner diameter to perform mechanical diameter adjustment under heating.

[0003] In the manufacturing method disclosed in this publication,
In particular, by measuring the outer diameter of the synthetic resin rod after diameter adjustment and controlling the number of revolutions of the gear pump of the coating extruder in accordance with the measured value, the outer diameter accuracy can be made uniform. I have to.

[0004] However, such a conventional method of manufacturing a rod made of synthetic resin has the following technical problems.

[0005]

That is, in the manufacturing method proposed in the above publication, the rotation speed of the gear pump is adjusted in order to control the extrusion amount of the coating extruder.
Maintenance when starting or stopping the gear pump is troublesome, and incorrect operation may damage the gear pump.

Further, in the manufacturing method proposed in the above publication, cutting by a diameter adjuster is employed in order to increase dimensional accuracy.
Since it causes loss of raw materials, improvement has been desired.

The present invention has been made in view of such conventional problems, and has as its object to provide a synthetic resin rod-shaped article which does not require troublesome maintenance and does not generate resin waste. It is an object of the present invention to provide a manufacturing method and a manufacturing apparatus.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method in which a thermoplastic resin is continuously coated on the outer periphery of a continuous rod made of a steel wire or a fiber-reinforced synthetic resin running at a predetermined speed. After being extruded and coated, in a method of manufacturing a synthetic resin rod that cools and solidifies to form a coating layer, the design outer diameter value of the synthetic resin rod to be manufactured,
A deviation value within an acceptable range is set in advance, and the production outside diameter value of the synthetic resin rod is measured for a predetermined time after the cooling and solidification, and the obtained plural production outside diameter values are within the deviation value. When the value was satisfied even once, the extrusion amount of the thermoplastic resin was maintained as it was.

According to the method of manufacturing a synthetic resin rod having the above-described structure, a synthetic resin rod having a highly accurate manufacturing outer diameter value with respect to a designed outer diameter value is subjected to diameter reduction processing. If no diameter reduction processing is performed, no resin dust is generated.

Further, in the present invention, a deviation value within an allowable range with respect to the design outer diameter value of the synthetic resin rod to be manufactured is set in advance, and the manufacturing outer diameter of the synthetic resin rod is manufactured. The value is measured for a predetermined time after cooling and solidifying, and when a plurality of obtained outer diameter values satisfy the deviation value at least once, the extrusion amount of the thermoplastic resin is maintained as it is.

The reason why such a control method is employed in the present invention is based on the following reasons.

In other words, in the method of manufacturing a synthetic resin rod according to the present invention, if the control of the extrusion amount is changed every time the production outer diameter value deviates from a preset deviation value, the extrusion amount is changed. As a result, the manufacturing outer diameter value may fluctuate greatly from the plus side to the minus side of the deviation value, or to the opposite side, leading to a so-called hunting phenomenon.

However, according to the knowledge of the present inventors, in the production of a synthetic resin rod having a thermoplastic resin coating on a steel wire or a fiber-reinforced synthetic resin rod as the object of the present invention, It is manufactured in a state where the outer diameter accuracy is quite stable, and even if the manufactured outer diameter value deviates from a preset deviation value, it is very small, and the extrusion amount is controlled so as to lead to a hunting (turbulence) phenomenon. When the value within the deviation value is satisfied even once, it has been found that the control for maintaining the extrusion amount of the thermoplastic resin as it is is more stable in the production outer diameter value.

In view of the above, the present invention employs the above-described control of the extrusion amount. According to such control, the width of the set deviation value is reduced while avoiding troublesome operations. As a result, the manufacturing outer diameter value can be further improved in accuracy.

In the method for producing a synthetic resin rod, when the production outer diameter value of the synthetic resin rod is measured for a predetermined time, a plurality of obtained production outer diameter values are within the deviation value. If the value is never satisfied, the extrusion rate can be increased or decreased according to the direction away from the deviation value.

Further, as the manufacturing outer diameter value, a maximum value and a minimum value within the predetermined time are obtained, and it can be determined whether or not the deviation value is satisfied from these maximum or minimum values.

Further, the coating layer is formed by a plurality of extruders arranged in a multistage manner, and the control of the extrusion amount can be applied to the extruder installed at the last stage.

Further, according to the present invention, a thermoplastic resin is continuously extruded onto an outer periphery of a continuous rod-shaped body such as a steel wire or a fiber-reinforced synthetic resin traveling at a predetermined speed by an extruder to cover the outer periphery.
In the apparatus for manufacturing a synthetic resin rod that cools and solidifies to form a coating layer, an outer diameter that is installed on the downstream side of the extruder and measures a manufacturing outer diameter value of the synthetic resin rod after cooling and solidification. Measuring device, comprising a control unit for controlling the extrusion amount of the synthetic resin of the extruder, based on the manufacturing outer diameter value detected by the outer diameter measuring device, wherein the control unit is to be manufactured For the design outer diameter value of the synthetic resin rod, a deviation value that is within an allowable range is set in advance, and a plurality of manufacturing outer diameter values obtained by the outer diameter measuring device are values within the deviation value. Was satisfied even once, the extruder was controlled so as to maintain the extruded amount as it was.

According to the apparatus for manufacturing a synthetic resin rod-like material thus configured, troublesome maintenance is not required and resin dust is not generated, similarly to the manufacturing method.

The extrusion rate of the extruder can be controlled by changing the rotation speed of a screw for supplying the thermoplastic resin to a die.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 5 show one embodiment of a method and an apparatus for manufacturing a synthetic resin rod according to the present invention.

The method and apparatus for manufacturing a synthetic resin rod shown in these figures are for producing a synthetic resin rod 10 having a cross section shown in FIG. After the molten thermoplastic resin is continuously extruded on the outer periphery of the continuous rod-shaped body 12 such as a steel wire or a fiber-reinforced synthetic resin running in v to cover the periphery thereof, the molten thermoplastic resin is cooled, The basic configuration is to form the coating layer 14.

In this embodiment, the continuous rod 12 has a circular cross-section having an outer diameter of D ₀ , and the coating layer 14 includes a first coating layer 14 a formed directly on the outer periphery of the continuous rod 12. ,
And a second coating layer 14b formed on the outer periphery of the first coating layer 14a.

[0024] In this case, the outer diameter D ₁ becomes when the continuous rod-like body 12 subjected to the first coating layer 14a of the annular predetermined thickness,
Outer diameter when subjected to the second coating layer 14a is not a D _2, the outer diameter D _{2 (off-design} diameter value) becomes the off-design diameter value of the synthetic resin rod member 10 to be manufactured I have.

In order to form such a coating layer 14,
In the case of the present embodiment, as shown in FIG. 2, the primary and secondary extruders 16, 18 for extruding a molten thermoplastic resin.
Are arranged in a continuous two-stage form.

The primary and secondary extruders 16 and 18 are provided with dies 16a and 18a for extruding the molten thermoplastic resin, rotation speed controllers 16b and 18b for supplying the resin to the dies 16a and 18a, respectively. The rotation speed control unit 16b,
18b, and driving inverters 16c and 18c.

[0027] downstream of the secondary extruder 18 has an outer diameter measuring device 20 for measuring the production outside diameter value D _n of the synthetic resin sticks 10 after cooling and solidifying is installed. The outer diameter measuring device 20 includes a main body 20a through which the synthetic resin rod 10 is inserted, and detects an outer diameter thereof, and a display unit 20b for displaying a measured value detected by the main body 20a.

In this embodiment, natural air cooling is used for cooling and solidifying the synthetic resin rod 10.
The main body 20a of the outer diameter measuring device 20 is installed at a position separated by a length L required for cooling from the die 18a of the secondary extruder 18.

In this case, the method of cooling the synthetic resin rod 10 is not limited to the natural air cooling employed in the present embodiment, but may be a forced air cooling or a water cooling method, or a cooling method suitably combining these methods. It may be a method.

The inverters 16 c and 18 c of the primary and secondary extruders 16 and 18 are connected to a wire diameter controller 22. The wire diameter control unit 22 is connected to a touch panel 24 for wire diameter control setting, and sends out a detection signal of the outer diameter measuring device 20.

The wire diameter controller 22 receives the detection signal of the outer diameter measuring device 20 and receives the detection signal from the outer diameter measuring device 20.
Is controlled as shown in FIGS. 3 and 4. In the case of this embodiment, the extruder is arranged in two-step form, but forms a coating layer 14 in multiple stages, manufacturing outside diameter value D _n of the synthetic resin sticks 10 to be manufactured In the case of this embodiment, only the extrusion amount of the secondary extruder 18 disposed in the last stage is controlled by the following procedure, and only the extrusion state of the last stage extruder is controlled. The extrusion rate of the primary extruder 16 is set to be always constant.

In the control procedure shown in FIGS. 3 and 4, the design outer diameter value D _{2 of} the synthetic resin rod 10 to be manufactured is determined.
Respect, to set the deviation value as a permissible range δ advance, produced outside diameter value D _n of the predetermined time of the synthetic resin shaped material 10 (Mississauga time to the same) was measured, with the outer diameter measuring device 20 multiple manufacturing outside diameter value D _n obtained is, to satisfy the values in the deviation δ at least once, and controls so as to maintain the extrusion amount of the secondary extruder 18.

More specifically, when the control procedure starts, first, in step 1, a product name is input, and in step 2, the designed outer diameter value of the resin-made rod 10 to be manufactured is set. D ₂ is input.

Next, in Step 3, the outer diameter tolerance value δ for the design outside diameter value D ₂ is input. This tolerance value δ
An upper limit value DHi and the lower limit value of the design outside diameter value _{D 2} DLo
For example, the width of the deviation value δ is ± 0.
It is set to, for example, 01 mm.

In the following step 4, the viewing times T1 and T2 are set. The sewing times T1, T2 in the case of this embodiment, a predetermined time to measure the production outside diameter value D _n of the synthetic resin shaped material 10 by the outer diameter measuring device 20,
For example, the viewing time T1 is 450 seconds, and the viewing time T2 is 600 seconds.
Set to seconds.

As will be described later, the observation time T1 is determined by _dividing the plurality of manufacturing outer diameter values D _n obtained by the outer diameter measuring device 20 with the deviation value δ.
When this condition is satisfied the value of the inner at least once, a measurement time by the outer diameter measuring device 20 to be applied, sewing time T2, a plurality of manufacturing outside diameter value D _n obtained in the outer diameter measuring device 20 , Deviation value δ
Is the measurement time by the outer diameter measuring device 20 that is applied when the value in is not satisfied even once.

[0037] In the case of this embodiment, prepared outside diameter value D _n, obtained by sewing time T1, if that does not satisfy once the value of the deviation value δ is extruded by the secondary extruder 18 Since the amount is changed, the subsequent measurement time by the outer diameter measuring device 20, that is, the viewing time T2 is made longer than T1, and the production outer diameter value D is set.
_{The observation} of the change of _n is strengthened.

[0038] Subsequently, in step 5, is set rotational speed of the screw of the secondary extruder 18, in a next step 6, manufactured outside diameter value D _n of the synthetic resin rod member 10 is measured by the outer diameter measuring device 20 Then, at the same time as this measurement, the timer set to the viewing time T1 starts.

[0039] Measurement of manufacturing outside diameter value D _n of the synthetic resin rod-shaped body 10, in step 7, the timer is continued until it is determined to have become the sewing time T1, in this sewing machine within the time T1,
A plurality of manufacturing outer diameter _values Dn are obtained, and each manufacturing outer diameter value Dn is obtained.
_n is stored in the memory of the control unit 22.

If it is determined in step 7 that the viewing time T1 has elapsed, the timer is stopped in step 8 and the process proceeds to step 9. In step 9, the maximum value Dmax and minimum value Dmin of the plurality of manufacturing outside diameter value produced outside diameter value D _n obtained in the sewing time T1 is calculated.

[0041] In the next step 10, whether the minimum value Dmin is larger than the lower limit value DLo for off-design diameter value _{D 2} set in step 3 is determined and the minimum value Dmin
Is smaller than the lower limit value DLo, the process proceeds to step S11.

In step 11, it is determined whether or not the maximum value Dmax is larger than the lower limit value DLo.
If x is smaller than the lower limit value DLo, step 12
Move to

In step 12, the screw rotation is accelerated so as to increase the extrusion amount of the secondary extruder 18, and the acceleration signal is sent from the control unit 22 to the inverter 18c of the secondary extruder 18. .

The process of increasing the extrusion amount is performed as follows.
Through steps 10 and 11, the procedure described above has reached the step 12, as indicated by the two-5, and the maximum value Dmax and minimum value Dmin of the manufacturing outside diameter value D _n measured in Mississauga time within T1 , they become both smaller than the lower limit value DLo a preset deviation value [delta], because apart from these downward, so that manufacturing outside diameter value D _n is larger than the lower limit value DLo, the extrusion rate Increase.

When such processing is completed, step 1
In Step 3, the timer is set to the viewing time T2, and Step 14 is performed.
Then, it is determined whether or not to end the outer diameter control, and if the outer diameter control is to be continued, the process returns to step 6.

On the other hand, if it is determined in step 11 that the maximum value Dmax is larger than the lower limit value DLo, the process shifts to step 15 to determine whether the maximum value Dmax is smaller than the maximum value DHi. Is determined.

In this step 15, the maximum value Dmax is
When it is determined that the value is larger than the large value DHi, FIG.
As shown by, the manufacturing outer diameter measured within the viewing time T1
Value D _nThe maximum value Dmax and the minimum value Dmin of
Between the lower limit value DLo and the upper limit value DHi of the determined deviation value δ.
The outer diameter D_nAre
In step 16, the secondary extruder 18 is
Send deceleration or acceleration signal to step 13 and proceed to step 13
I do.

[0048] The state shown by a two-5, i.e., the maximum value Dmax and the minimum value Dmi manufacturing outside diameter value _{D n}
n is larger than a predetermined width of the deviation value δ, and this spans between the lower limit value DLo and the upper limit value DHi, such as the stability of the production of the synthetic resin rod 10. From the viewpoint, it hardly occurs.

However, this occurrence probability is not zero,
If it is left unattended if it occurs, a runaway of the manufacturing apparatus will result, so in the present embodiment, step 16 and the like are provided to deal with this.

If it is determined in step 15 that the maximum value Dmax is smaller than the maximum value DHi, the flow chart shown in FIG.
As shown by the two, and the maximum value Dmax and minimum value Dmin of the manufacturing outside diameter value D _n measured in Mississauga time within T1 is, they become as to straddle the lower limit DLo a preset deviation value δ , prepared outside diameter value D _n it is, at least once, is determined to have satisfied the allowable deviation value [delta].

When such a determination is made, the control signal is not sent from the control unit 22 to the secondary extruder 18 so that the extruded amount is maintained as it is. The time is set to T1, and the process proceeds to step S14.

On the other hand, if it is determined in step 10 that the minimum value Dmin is larger than the lower limit value DLo, the process proceeds to step 17 where it is determined whether the minimum value Dmin is smaller than the upper limit value DHi. Is determined.

If it is determined in step 17 that the minimum value Dmin is smaller than the upper limit value DHi, as shown in FIG. 5, the maximum value Dmax is smaller than the maximum value DHi or larger. even in the case of any production outside diameter value D _n is at least once, it can be determined that it has satisfied the allowable deviation value [delta], in this case, the secondary extruder 1
In step 8, the control unit 22 does not send a control signal, and the extruding amount is maintained as it is. In step 16, the timer is set to the viewing time T1, and the process proceeds to step 14.

If it is determined in step 17 that the minimum value Dmin is larger than the upper limit value DHi,
As shown by the two, and the maximum value Dmax and minimum value Dmin of the manufacturing outside diameter value D _n measured in Mississauga time within T1 is, have both larger than the upper limit value DHi a preset deviation value δ , Since they are spaced upward from these values,
As manufacturing outside diameter value D _n is smaller than the upper limit value DHi, it is necessary to achieve a reduction in extrusion rate.

Therefore, when the determination is made in step 17, the screw rotation of the secondary extruder 18 is decelerated in step 18, and this deceleration signal is sent from the control unit 22 to the inverter of the secondary extruder 18. 18c.

When such processing is completed, the timer is set to the viewing time T2 in step 19, and it is determined in step 14 whether or not the outer diameter control is to be terminated. When performing control, return to step 6;
When ending the outer diameter control, the procedure ends.

[0057] Now, according to the manufacturing method and manufacturing apparatus of the constructed synthetic resin sticks 10 as described above, equipped with a outside diameter value D _n of precision with respect to the design outside diameter value D ₂ Synthesis A resin rod 10 is obtained without performing a diameter-sizing process,
Unless the diameter is reduced, resin waste does not occur.

Also, in this embodiment, the manufacturing
Design outer diameter value D of synthetic resin rod 10 ₂Acceptable for
The deviation value δ is set in advance in the range of
Outer diameter D of the product 10_nAfter cooling and solidifying for a predetermined time (viewing
Time T1) Measured and obtained multiple production outer diameter values D_nBut,
If the value within the deviation value δ is satisfied even once, the thermoplastic resin
Maintain the extrusion rate.

The reason why such a control method is employed in this embodiment is based on the following reason.

[0060] That is, the control of the extrusion amount in the manufacturing method of synthetic resin shaped material 10, when manufactured outside diameter value D _n is changed every time the outside from the deviation value δ to be set in advance, with the change of extrusion rate, production outer diameter value D _n is, can lead to so-called hunting (hunting) phenomenon varies greatly to the minus side from the plus side of the deviation value [delta].

However, in the production of a synthetic resin rod 10 having a thermoplastic resin coating on a steel wire, a fiber reinforced synthetic resin rod 12 or the like, which is the object of the present embodiment, the present inventors know. According to give an outer diameter is produced at a fairly stable, manufactured outside diameter value D _n is a negligible even deviate from the deviation value δ to be set in advance, hunting (hunting) of the extrusion amount as lead to phenomena from performing control also to satisfy the values in the deviation even once, who directly control for maintaining the extrusion amount of the thermoplastic resin is produced outside diameter value D _n is found to be stable.

Therefore, in the present embodiment, a predetermined viewing
Manufacturing outer diameter value D within time T1 _nMaximum value Dmax of
And a minimum value Dmin, and a deviation value δ is calculated from these values.
It is determined whether or not the value is satisfied, and the value within the deviation value δ is determined even once.
If satisfied, keep the thermoplastic resin extrusion rate as it is
Control, and the control
For example, you can set a deviation value while avoiding troublesome operations.
By reducing the width of δ, the production outer diameter D_nof
High accuracy can be achieved.

In the above embodiment, the case where the synthetic resin rod 10 is manufactured using the extruders 16 and 18 arranged in two stages has been exemplified. However, the present invention is not limited to this. However, one extruder may be used, or three or more extruders may be provided.

[0064]

As described above in detail, according to the method and the apparatus for manufacturing a synthetic resin rod according to the present invention, troublesome maintenance is not required and no resin dust is generated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a rod-shaped object manufactured by a method and an apparatus for manufacturing a synthetic resin rod-shaped object according to the present invention.

FIG. 2 is an overall layout view showing one embodiment of the apparatus for manufacturing a synthetic resin rod according to the present invention.

FIG. 3 is a flowchart illustrating an example of a control procedure performed by a control unit of the manufacturing apparatus illustrated in FIG. 2;

FIG. 4 is a flowchart illustrating an example of a control procedure performed by a control unit of the manufacturing apparatus illustrated in FIG. 2;

FIG. 5 is an explanatory diagram of a determination state performed in the flowchart shown in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Synthetic resin rod 12 Continuous rod 14 Coating layer 14a First coating layer 14b Second coating layer 16 Primary extruder 18 Secondary extruder 20 Outer diameter measuring device 22 Control unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hiroshi Kimura 2-1-1, Yabuta Nishi, Gifu City, Gifu Prefecture Ube Nitto Kasei Co., Ltd. F term (reference) 4F207 AD15 AG14 AP11 AR09 AR12 AR14 KA01 KA17 KB18 KK12 KL96 KM06 KM15

Claims (6)

[Claims] 1. A thermoplastic resin is continuously extruded around the outer periphery of a continuous rod made of a steel wire or a fiber-reinforced synthetic resin which travels at a predetermined speed, and then cooled and solidified to form a coating layer. In the method of manufacturing a synthetic resin rod, a deviation value within an allowable range is set in advance with respect to a design outer diameter value of the synthetic resin rod to be manufactured. The outer diameter value is measured for a predetermined time after the cooling and solidification, and when a plurality of obtained outer diameter values satisfy the value within the deviation value at least once, the extrusion amount of the thermoplastic resin is maintained as it is. A method for producing a synthetic resin rod. 2. The method for producing a synthetic resin rod according to claim 1, wherein when the production outer diameter value of the synthetic resin rod is measured for a predetermined time, a plurality of obtained production outer diameter values are: A method of manufacturing a synthetic resin rod, wherein the extrusion amount is increased or decreased in accordance with a direction away from the deviation value when a value within the deviation value is never satisfied. 3. The manufacturing outer diameter value is obtained by obtaining a maximum value and a minimum value within the predetermined time, and determining whether or not the deviation value is satisfied from the maximum value or the minimum value. The method for producing a synthetic resin rod according to claim 1 or 2. 4. The method according to claim 1, wherein the coating layer is formed by a plurality of extruders arranged in a multistage manner, and the control of the extruding amount is applied to an extruder installed at the last stage. 4. The method for producing a synthetic resin rod according to any one of items 3. 5. An extruder is used to continuously extrude and coat a thermoplastic resin on the outer periphery of a continuous rod made of a steel wire or a fiber-reinforced synthetic resin or the like which runs at a predetermined speed, and then cools and solidifies to form a coating layer. An apparatus for measuring the production outer diameter of the synthetic resin rod after cooling and solidification, wherein the outer diameter measuring device is installed on the downstream side of the extruder; A control unit for controlling the amount of the synthetic resin to be extruded by the extruder based on the production outside diameter value detected by a diameter measuring device, wherein the control unit controls the amount of the synthetic resin rod to be produced. For the design outer diameter value, a deviation value within an allowable range is set in advance, and when a plurality of manufacturing outer diameter values obtained by the outer diameter measuring device satisfy the value within the deviation value at least once. Controlling the extrusion amount of the extruder to be maintained as it is. Equipment for manufacturing rods made of synthetic resin. 6. The apparatus according to claim 5, wherein the control of the extruding amount of the extruder is performed by changing the number of revolutions of a screw for supplying the thermoplastic resin to a die. .