JP2000326392A - Method and apparatus for producing long molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately keep the cross-sectional shape of a coating layer with respect to a change in production linear velocity even in the extrusion not only of a circular cross section but also of a profile cross section. SOLUTION: A long molded object containing a thermoplastic resin part such as a spacer 6 is produced by using at least an extruder 4 and a taking-over machine 7. In this case, when the production linear velocity of the long molded object is changed, the number of rotations of a screw to the production linear velocity is determined on the basis of the preliminarily calculated relation between the number of rotations of the screw of the extruder 4 and the emitting amt. of the thermoplastic resin extruded from the extruder so that a ratio of the production linear velocity and the emitting amt. becomes constant and, according thereto, the number of rotations of the screw and production linear velocity are changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is particularly suitable for producing a long molded article having a modified cross section such as a spacer formed by extruding a coating made of a thermoplastic resin having a spiral groove on the surface thereof around a tensile strength member. The present invention relates to a method and an apparatus for producing a long molded body applicable to the production of a circular long molded body.

[0002]

2. Description of the Related Art A spacer formed by extruding a coating made of a thermoplastic resin having a spiral groove on the surface thereof around a strength member is usually manufactured by the following apparatus. FIG. 4 is a front view showing a main part of the manufacturing apparatus, wherein 1 is a supply reel, 2 is a tensile member, 3 is a tension control mechanism, 4 is an extruder, 4a is a crosshead, 4b is a screw, and 4c is a screw. Drive motor, 5 is a cooling water tank, 6 is a spacer, 7 is a take-off machine,
8 is a take-up reel.

[0003] Tensile member 2 unreeled from supply reel 1
Is a linear body made of steel wire, steel stranded wire, FRP, or the like, and a thermoplastic resin coating layer such as polyethylene extruded from an extruder 4 is provided around the linear body, and a thermoplastic resin coating layer is formed in a cooling water tank 5. Is cooled to form a spacer 6, and is taken up on a take-up reel 8 while applying a take-up force by a take-up machine 7. At the same time, by rotating the die attached to the crosshead 4a of the extruder 4 around the axis in the traveling direction, a spiral groove for accommodating an optical fiber core or the like is formed on the surface of the coating layer of the thermoplastic resin. . The tension control mechanism 3 is a device that controls the tension of the tensile member 2.

[0004]

When a spacer is manufactured by the above-described manufacturing apparatus, at the time of manufacturing, at the time of manufacturing, firstly, based on the design weight of the thermoplastic resin, the manufacturing linear speed of the take-off machine,
Set the screw rotation speed to be the discharge amount of the thermoplastic resin corresponding to the production linear speed, perform test extrusion at a relatively low production linear speed of several meters / minute, and coat the extruded thermoplastic resin. Check if the layer shape is as designed.

After confirming that a coating layer having a predetermined good cross-sectional shape can be obtained, the number of rotations of the screw and the production line speed are increased, and a steady operation state at a high production line speed of several tens m / min is established. Transition. Also, when manufacturing a normal insulated wire provided with a coating layer made of a thermoplastic resin having a circular cross section on the conductor, the same operation as in the case of the above spacer, that is, confirmation of the cross-sectional shape by test extrusion at low speed, The shift to steady operation at high speed is being performed.

In the case of producing a long molded body having a circular cross section, an outside diameter measuring machine is installed at a position where the outside of the cooling water tank is measured, and the outer diameter of the completed long molded body is measured. When the diameter deviates from the design value, control is performed such that the outer diameter of the elongated molded body matches the design value by adjusting the production linear speed of the take-off machine. However, in the case where the cross section is not circular but irregular, such as a spacer, it is difficult to set and measure a point that can represent the entire size with one dimension, such as the outer diameter in the case of a circular cross section. In particular, since the cross-sectional shape of the spacer is spirally rotated in the longitudinal direction, considerable difficulty is involved, such as the need to rotate the measuring device.

Therefore, in the case of the spacer, the screw rotation speed is increased in accordance with the rate of increase in the production linear speed during high-speed operation, based on the screw rotation speed and the production linear speed at low speed ejection. Has shifted from low-speed operation to high-speed operation. However, since the number of rotations of the screw and the discharge amount of the thermoplastic resin from the extruder (the weight of the thermoplastic resin extruded per unit time) are not necessarily in a proportional relationship, the rotation of the screw depends on the increasing rate of the production linear speed. When the number is increased, the cross-sectional shape of the coating layer of the spacer is changed by an amount corresponding to a deviation from the proportional relationship between the screw rotation speed and the discharge amount, which causes a shape change.

Therefore, in order to further correct the shape fluctuation due to the shift, a sample of the cross-sectional shape is taken even after the shift to the high-speed operation, and the screw rotation speed or the production line is adjusted according to the shape shift in the cross-sectional shape sample. The correction is made by correcting the speed. In order to shift to a stable operation state, not only such a procedure and labor are required, but also a product manufactured during that time cannot be made into a good product, and a large amount of dust is generated.

The present invention provides a method and an apparatus for manufacturing a long molded body capable of accurately maintaining the cross-sectional shape of a coating layer with respect to a change in a production linear velocity not only in extruding a circular cross section but also a deformed cross section. Is what you do.

[0010]

According to the present invention, there is provided a method for producing a long molded article having at least an extruder and a take-off machine, the long molded article having a portion made of a thermoplastic resin. In changing the production linear speed of the long molded product, the production linear speed and the discharge speed are determined based on the relationship between the screw speed of the extruder previously obtained and the discharge amount of the thermoplastic resin extruded from the extruder. The screw rotation speed with respect to the production linear speed is determined so that the ratio of the amounts is constant, and accordingly, the screw rotation speed of the extruder is changed, and the production linear speed is changed.

Thus, even during the change of the production linear speed, the screw rotation speed is sequentially corrected so that the discharge amount of the thermoplastic resin is proportional to the production linear speed. The amount of the plastic resin can be made constant, and the dimensional fluctuation in the longitudinal direction of the long molded body can be suppressed.

In changing the screw rotation speed and the production linear speed, first, the screw rotation speed of the extruder is changed, and the time until the discharge rate changes due to the change in the screw rotation speed is delayed. If the production linear speed is changed, the delay in the change in the discharge amount of the thermoplastic resin from the change in the screw rotation speed is corrected, and the longitudinal partial dimensional change of the long molded body due to the delay is corrected. Can be eliminated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a long molded article according to the present invention is also performed by using an apparatus having an extruder and a take-off machine similar to the conventional method for manufacturing a spacer shown in FIG. Do. FIG. 1 shows a portion of the manufacturing apparatus related to the present invention, and the same reference numerals as those in FIG. 4 denote the same parts. Reference numeral 9 denotes a production linear speed control mechanism.

The production linear speed control mechanism 9 determines the number of rotations of the screw of the extruder 4 and the discharge amount of the thermoplastic resin extruded from the extruder (weight of the thermoplastic resin extruded per unit time). The data indicating the relationship is stored, and when changing from one manufacturing linear speed to another manufacturing linear speed, so that the discharge amount changes in proportion to the manufacturing linear speed,
It has a calculation unit for calculating the screw rotation speed with respect to the production linear speed, and has a command unit for instructing the extruder 4 on the calculated screw rotation speed and instructing the take-off machine 7 on the production linear speed.

FIG. 2A is a graph showing an example of the relationship between the screw rotation speed and the discharge amount of the thermoplastic resin of the extruder used in the production.
(B) is a graph showing that the production linear velocity and the discharge amount are in a proportional relationship. The data of FIG. 2A is obtained in advance and stored in the manufacturing linear speed control mechanism 9.

At the time of production, at the time of production, based on the design weight of the thermoplastic resin, first, a production linear speed as low as several m / min and a screw which produces a discharge amount of the thermoplastic resin which is conspicuous with the production linear speed. The number of rotations is set, and extrusion is performed on a trial basis at a low production linear speed, and it is confirmed whether the shape of the extruded spacer 6 is as designed. If the shape of the extruded spacer is not as designed, the screw rotation speed or the production linear speed is changed little by little to make adjustments to obtain the designed shape. Then, after it is confirmed that the cross-sectional shape is as designed, the production linear velocity is increased as follows.

When the production linear speed is to be changed from V ₀ to V ₁ , the arithmetic unit of the production linear speed control mechanism 9 calculates the current screw rotation speed R ₀ based on the data shown in FIG. A current discharge amount N ₀ is calculated, and N ₁ / N is calculated according to FIG.
V ₁ = and N ₀ / V ₀ The discharge amount N ₁ in the case of the so as to manufacture the linear velocity V ₁ calculated, obtaining the screw rotation speed R ₁ corresponding to the discharge amount N ₁ from the data shown in FIG. 2 (A) .

[0018] Then, at the command of the production line speed control mechanism 9, the screw rotation speed R ₁ to extruder 4, the take-up machine 7 instructs the manufacturing line speed V _1, changing respectively. Usually, the response speed of the extrusion discharge amount to the change in the screw rotation speed of the extruder 4 is slower than the response speed of the change in the production linear speed of the take-off machine. It changes according to the response speed of the screw rotation speed change.

Even if the production linear velocity changes greatly, if the production linear velocity in the middle is increased linearly, V ₁ ,
Since N ₁ and R ₁ can be calculated by the calculation unit and commanded by the command unit to the extruder and the take-off unit, even in the process of changing the production linear speed, the discharge amount is proportional to the production linear speed. Can be controlled.

FIG. 3 is a diagram showing an example of such a control method, in which the horizontal axis represents time and the vertical axis represents the set production linear speed, the production linear speed of the take-off machine, and the discharge of the extruder from the top. Amount and screw rotation number are shown. Set production line speed from V ₀ to V ₁
When changing to, it receives an instruction production line speed control mechanism, produced linear speed of take-up machine rises toward the V ₀ over a certain time at a certain ratio along the line 12 to V _1.

In addition, the discharge amount is adjusted to line 13
It is required to increase from N ₀ to N ₁ along the line. Therefore, the arithmetic unit of the manufacturing linear speed control mechanism uses the line 13 for changing the screw rotation speed from the line 13 and FIG.
4 is calculated, and a command to change the screw rotation speed along the line 14 is given from the command unit to the extruder, thereby satisfying the discharge amount requirement. In this case, the production linear speed of the take-off machine usually increases linearly, but the screw rotation speed of the extruder increases along the curve.

The screw 4b of the extruder 4 has a length of several tens cm to several meters, and the thermoplastic resin advances along the screw and is extruded from the crosshead 4a. Does not directly change the discharge amount of the thermoplastic resin from the extruder, and the discharge amount changes slightly later than the screw rotation speed. Therefore, when the screw speed of the extruder and the production linear speed of the take-off machine are simultaneously changed, the amount of the thermoplastic resin per length of the long molded body differs from the expected value during the delay. become.

The actual discharge rate of the extruder changes after a time ΔT behind the line 13 and changes along the line 13 ′. Therefore, as shown in a line 12 'in FIG. 3, if the change in the production line speed of the take-off machine is delayed by a time ΔT corresponding to the delay time, the change in the line speed of the take-up machine is caused by the line 13' Since the change in the discharge amount indicated by 'and the change in the production linear velocity can be matched, it is possible to prevent the elongated molded product from becoming thinner or thicker in the longitudinal direction.

When the production linear velocity changes slowly or when the production linear velocity does not change significantly, the shape variation of the long molded body due to the delay in the change in the discharge amount with respect to the change in the screw rotation speed falls within an acceptable range. In such a case, the change in the number of revolutions of the screw and the change in the production linear speed of the take-off machine may be simultaneous.

As described above, the method and apparatus for producing a long molded article according to the present invention have been described by taking as an example a spacer provided with a coating layer having a spiral groove on the surface of a tensile strength member. Not only can it be applied to the case where a thermoplastic resin coating layer is provided around the centerline body, such as the manufacture of insulated wires that apply a circular coating to the cable, the manufacture of cables that apply an external coating of a thermoplastic resin on the cable core, etc. Circular pipe without centerline,
The present invention can be applied to the manufacture of a long molded body made of a thermoplastic resin such as a rod-shaped body having an irregular cross section.

Further, in the above-described case, the case where the change in the production linear speed is changed from the low production line speed at the time of tapping to the high normal operation speed has been described. Can also be applied when changing from high speed to low speed.

[0027]

According to the method for producing a long molded article of the present invention, when the production linear velocity of the long molded article is changed, the screw speed of the extruder and the thermoplastic resin extruded from the extruder are determined in advance. Based on the relationship between the amount of resin discharged, the screw rotation speed is determined so that the ratio between the production linear speed and the discharge amount is constant, and the screw rotation speed and the production linear speed are changed accordingly. Even during speed changes,
The screw rotation speed is sequentially corrected so that the discharge amount of the thermoplastic resin is proportional to the production linear speed, and the dimensional fluctuation in the longitudinal direction of the long molded body can be suppressed. Further, it is possible to manufacture a long molded body having a stable shape in the longitudinal direction without installing an outer diameter measuring machine.

In changing the screw rotation speed and the production linear speed, first, the screw rotation speed of the extruder is changed, and after a certain period of time, the production linear speed of the take-off machine is changed. Since it is possible to correct the delay in the change in the discharge amount of the thermoplastic resin due to the change in the number of revolutions, even if the change in the production linear speed is large, even if the change in the production linear speed is fast, the long line accompanying the delay It is possible to eliminate partial dimensional fluctuation in the longitudinal direction of the molded body.

The method and apparatus for producing a long molded article according to the present invention can be applied to the formation of a coating layer having a circular cross section, but it is difficult to measure the dimensions with an outer diameter measuring device or the like. It is suitable for manufacturing spacers and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a portion related to a main part of the present invention in a device for manufacturing a long molded body of the present invention.

FIG. 2A is a graph showing a relationship example between a screw rotation speed and a discharge amount of a thermoplastic resin of an extruder,
(B) is a graph showing that the production linear velocity and the discharge amount are in a proportional relationship.

FIG. 3 shows an example of a control method according to the manufacturing method or the manufacturing apparatus according to the present invention, in which time elapses, a set manufacturing linear speed, a take-off machine manufacturing linear speed, an extruder discharge rate, and a screw rotation. It is a figure showing the relation with a number.

FIG. 4 is a front view showing a main part of a manufacturing apparatus of a spacer which is an example of a long molded body.

[Explanation of symbols]

1: supply reel 2: tensile strength member 3: tension control mechanism 4: extruder 4a: cross head 4b: screw 4c: screw drive motor 5: cooling water tank 6: spacer 7: take-up machine 8: take-up reel 9: production line Speed control mechanism 11: Change line of set production linear speed 12: Change line of production linear speed of take-off machine (when changing simultaneously with screw rotation speed) 12 ': Change line of production linear speed of take-off machine (screw rotation) 13: Extruder discharge amount change line (assuming that it changes simultaneously with screw rotation speed) 13 ': Extruder discharge amount change line (actual value) 14: Screw rotation speed change line

Continued on the front page (72) Inventor Teruo Araki 1F, Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa F-term in Sumitomo Electric Industries, Ltd. Yokohama Works 4F207 AD18 AR09 AR14 AR20 KA01 KA17 KB18

Claims (3)

[Claims] In a method for producing a long molded body having a portion made of a thermoplastic resin using at least an extruder and a take-off machine, a method is used in which the production linear speed of the long molded body is changed beforehand. Based on the relationship between the screw rotation speed of the extruder and the discharge amount of the thermoplastic resin extruded from the extruder, the screw rotation speed with respect to the production linear speed so that the ratio between the production linear speed and the discharge amount is constant. A method for producing a long molded article, comprising: determining a rotational speed of a screw of the extruder based on the determined value; and changing a production linear velocity by the take-off machine. 2. In changing the screw rotation speed of the extruder and the production linear speed of the take-off machine, first change the screw rotation speed, and change the time until the discharge rate changes due to the change in the screw rotation speed. The method for producing a long molded body according to claim 1, wherein the production linear velocity is changed by a take-off machine with a delay. 3. An apparatus for producing a long molded body made of a thermoplastic resin, comprising at least an extruder having a screw and a take-off machine. Based on the stored data relating to the relationship between the rotation speed of the screw and the discharge amount of the thermoplastic resin extruded from the extruder and the set production linear speed, the production linear speed is controlled so that the ratio between the production linear speed and the discharge amount becomes constant. A production line speed control comprising: a calculation unit for determining a screw rotation speed for the extruder; and a command unit for giving a screw rotation speed command to the extruder based on the calculation result and giving a production linear speed command to the take-off machine. An apparatus for manufacturing a long molded body, comprising a mechanism.