JPH07232367A - Molding of h-shape slot rod of optical fiber cable - Google Patents

Abstract

PURPOSE:To devise a molding method reducing extrusion resistance while ensuring the molding accuracy of an H-shape slot rod to increase line speed to enhance the molding efficiency of the rod still more. CONSTITUTION:A bridge part 11 is passed through a rotary molding die (rotary die) fitted with a molding nozzle having an H-shape cross section and the left and right side parts of an H-shape slot rod are molded by the left and right side parts of the rotary die to be bonded to both ends of the bridge part 11 in a molten state to form the slot rod having an H-shape cross section by extrusion molding. The H-shape slot rod is taken up while a winder 30 is rotated in matching relation to the rotation of the rotary die to mold the H-shape slot rod of an optical fiber cable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a plastic rod for an optical fiber cable, the slot rod having an H-shaped cross section (hereinafter referred to as "H-shaped slot rod") having a spiral groove on the outer circumference. The present invention is related to the H-shaped slot rod, and the line speed at the time of molding the H-shaped slot rod can be increased to remarkably improve the slot rod molding efficiency.

[0002]

2. Description of the Related Art As a housing for an optical fiber tape capable of high-density mounting, a tension member 2 is embedded in the center and two spiral grooves (grooves for accumulating and stacking optical fiber tapes are provided on the outer periphery thereof. ) 3 formed H-shaped slot rod 1 (FIG. 4) has been invented by the applicant. This H-shaped slot rod 1 is manufactured by extrusion molding. In this molding method, in order to form the above-mentioned spiral groove during the extrusion molding, the extrusion molding die is slowly rotated to form a spiral H-shaped rod. This is a forming method in which a shaped slot rod is formed and is wound around a winding device. In the above-mentioned molding method, molten synthetic resin is extruded from a rotating molding die, and a spiral groove 3 is formed on the outer periphery to form an H-shaped cross section including a bridge portion 4 and left and right semicircular portions 5. Therefore, if the extrusion molding speed, that is, the line speed exceeds a certain limit, the molding accuracy of the groove of the slot rod decreases in proportion to the line speed. This line speed is inversely proportional to the extrusion resistance due to the viscosity of the resin, and is proportional to the extrusion pressure. Therefore, in the conventional molding method, since there is a limit to the extrusion pressure, in order to ensure the predetermined molding accuracy, there is no choice but to stop the line speed at a fixed limit commensurate with the extrusion pressure,
Therefore, the molding efficiency cannot be improved.

[0003]

SUMMARY OF THE INVENTION The present invention aims to further improve the molding efficiency of an H-shaped slot rod. Therefore, while ensuring a predetermined molding accuracy, the extrusion resistance is reduced and the line speed is increased. It is an object to devise a method for forming an H-shaped slot rod so that it can be achieved.

Regarding the first invention,

Means for Solving the Problems The means for the first invention taken to solve the above problems is constituted by the following elements (a) and (b). (A) The bridge portion is passed through a rotating forming die with a forming nozzle having an H-shaped cross section to form the left and right side portions of the H-shaped slot rod from the left and right side portions of the rotating forming die, and the side portion is Extruding an H-shaped slot rod by fusion-bonding to both ends of the bridge portion, and (b) winding the H-shaped slot rod while rotating the winding device according to the rotation of the rotating molding die. The bridge portion may be formed in a step before the forming step using a rotating forming die having an H-shaped cross section, or may be formed in advance and wound.

[0005]

[Operation] With a molding nozzle with a H-shaped cross section, melted synthetic resin is extruded from the left and right side parts of a rotating molding die to extrude the left and right side parts, and at the same time, it is connected to an already cross-linked unbridged bridge part. Therefore, the shape of the die for extrusion molding on the left and right sides is simpler in cross-sectional shape than the shape of the die for extrusion molding a conventional H-shaped slot rod in one step, and Small surface area.
Therefore, the processing resistance (extrusion resistance) by the molding die for extrusion molding is small, the extrusion speed under a predetermined extrusion pressure can be increased, and the line speed can be increased. A fixed die with a molding nozzle of rectangular cross-section for molding the bridge is placed in front of a rotating molding die with a molding nozzle of H-shaped cross section, and the fixed die with the molding nozzle of H-shaped cross-section Even if the side part is continuously formed, the extrusion speed in the step of forming the bridge part should be sufficiently faster than the extrusion speed from the die for extruding the left and right side parts for the same reason as above. There is no problem because you can. When the bridge portion is preformed and wound up and is used for forming an H-shaped slot rod by a rotating forming die with a forming nozzle having an H-shaped cross section, the bridge portion is passed at the time of passing through the rotating forming die. It is necessary to ensure that both ends of the are heated to the extent that they can be melt-bonded to the extruded sides. The molding die rotates, whereby a spiral groove is formed while the bridge portion is twisted, but the bridge portion is plastically deformed in the twisting direction by the twisting. Since the H-shaped slot rod is wound while the winding drum rotates in accordance with the rotation of the forming die, the bridge portion can be smoothly wound by the winding device in a twisted state, and there is no problem.

Regarding the second invention,

Means for Solving the Problems The means of the second invention taken to solve the above problems is constituted by the following elements (a) and (b). (A) The bridge portion is passed through a non-rotating forming die with a forming nozzle having an H-shaped cross section, the left and right side portions of the non-rotating forming die form the left and right side portions of the H-shaped slot rod, and both ends of the bridge portion are formed. And extruding a slot rod having an H-shaped cross section by fusion-bonding the side portions to each other, and (b) rotating the winding device also in a direction in which the H-shaped slot rod is twisted. Winding the H-shaped slot rod by the above winding device while transforming the groove into a spiral groove.

[0007]

[Operation] Since the forming dies that form the left and right sides of the H-shaped slot rod do not rotate, the operation is the same as that of the first invention except that the H-shaped slot rod having the linear groove is extruded. There is no. Although the H-shaped slot rod is extruded by the forming die as having a straight groove, the winding device also rotates in the direction of twisting the H-shaped slot rod, so that the extruding device and the winding device can be rotated. The H-shaped slot rod is twisted in the meantime, and its linear groove is deformed into a spiral shape, and the H-shaped slot rod is wound by the winding device as it is. Since the H-shaped slot rod is twisted at a high temperature, the H-shaped slot rod is plastically deformed by the twist to form an H-shaped slot rod having a spiral shape.

[0008]

[Examples] Next, an example in which molding of a bridge portion and molding by a molding die having an H-shaped cross section are continuously performed will be described with reference to the drawings. A bridge portion extruder 10 having a fixed die with a forming nozzle having a rectangular cross section and a slot rod extruder 20 having a rotating forming die (rotating die) with a forming nozzle having an H-shaped cross section are arranged in front and rear. A slot rod winding device 30 that rotates in the direction of arrow A is arranged behind it. The tension member 2 is supplied from the reel 40 to the bridge extrusion molding machine 10,
The tension member 2 is formed by the bridge extrusion molding machine 10.
The bridge portion 11 in which is embedded is extruded. The bridge portion 11 extruded from the bridge portion extrusion molding machine 10 is immediately supplied to the slot rod extrusion molding machine 20. The left and right semi-circular portions 21 of the slot rod are formed by the rotary die with a forming nozzle having an H-shaped cross section of the slot rod extruder 20.
21 is molded, and the semicircular portions 21 and 21 are melt-bonded to both ends of the bridge portion 11 to form an H-shaped slot rod 22. Since the rotary die of the slot rod extruder 20 rotates in the direction of arrow A,
The shaped slot rod 22 is twisted in the direction of arrow A, and the groove 23
Becomes a spiral groove. The take-up reel of the slot rod take-up device 30 rotates in the direction of arrow A in accordance with the rotation of the slot rod extruder 20 and the H-shaped slot rod 2 extruded from the slot rod extruder 20.
Wind up 2. When molding an H-shaped slot rod made of PBT resin having a diameter of 7 mm and a groove having a width of 3.5 mm and a depth of 2.0 mm, the line speed of the slot rod extruder 20 can be increased to 15 m / min. This corresponds to 3 times the line speed (5 m / min) in the conventional molding method. Since the bridge portion 11 passes through the rotary die of the slot rod extrusion molding machine 20 in an uncrosslinked state, the resistance of the bridge portion to the twist by the rotary die is extremely small, and the deformation of the bridge portion due to the twist is elastic. Since it is not a deformation (it is a plastic deformation), there is no elastic return after passing through the rotary die with the H-shaped cross section of the slot rod extruder 20 and therefore by using the preformed bridge portion 11. The forming accuracy of the H-shaped slot rod 22 by the rotary die is not affected at all. The above embodiment is an invention of forming a spiral groove by rotating the molding die, that is, an example of the first invention, but the molding die is not rotated, that is, in the second invention, the groove is Since the linear groove is formed, the winding device 30 is also rotated in the arrow A direction so as to twist the H-shaped slot rod 22 in the arrow A direction in order to deform the linear groove.

[0009]

[Effect] The invention which has solved the above-mentioned problems is not yet known. Therefore, it is possible to solve the novel problems described above, and to improve the line speed of the slot rod extrusion molding while securing a sufficient groove machining accuracy, thereby significantly improving the production efficiency. is there. further,
Producing a slot rod by a conventional processing method using a plastic material having poor extrusion processability is poor in productivity. Therefore, in the past, it was practically impossible to use a plastic material having poor workability in extrusion for manufacturing the slot rod, but according to the present invention, a certain line speed can be secured even for a material having poor workability in extrusion molding. Therefore, even a material having good workability in extrusion molding can be actually used for manufacturing the H-shaped slot rod. This is also a great advantage of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of the present invention.

FIG. 2 is a schematic sectional view of a rotary die of a slot rod extruder.

FIG. 3 is a sectional view taken along line XX in FIG.

FIG. 4 is a sectional view of a conventional H-shaped slot rod.

[Explanation of symbols]

 1, 22 ... H-shaped slot rod 2 ... Tension member 3, 23 ... Groove 4, 11 ... Bridge part 5, 21 ... Semi-circle part 10 ... Bridge part extrusion molding machine 20・ ・ ・ Slot rod extruder 30 ・ ・ ・ Slot rod winding device 40 ・ ・ ・ Reel

Claims (2)

[Claims] 1. A method of molding an H-shaped slot rod in which two spiral grooves are formed on the outer circumference of the rod by extrusion molding, wherein the bridge portion of the H-shaped slot lot is rotated with a molding nozzle having an H-shaped cross section. The left and right side portions of the H-shaped slot rod are molded by the left and right side portions of the rotating molding die through the die, and the side portions are melt-bonded to both ends of the bridge portion to form a slot rod having an H-shaped cross section. A method for molding an H-shaped slot rod of an optical fiber cable in which extrusion molding is performed, and the H-shaped slot rod is wound while rotating the winding device in accordance with the rotation of the rotating molding die. 2. A method for molding an H-shaped slot rod in which two spiral grooves are formed on the outer periphery of the rod by extrusion molding, wherein the bridge portion of the H-shaped slot lot has a H-shaped cross section and is not rotated. The left and right side portions of the non-rotating forming die are passed through a die to form the left and right side portions of the H-shaped slot rod, and the side portions are melt-bonded to both ends of the bridge portion to form a slot rod having an H-shaped cross section. Extrusion molding is performed, and the winding device is rotated in a direction in which the H-shaped slot rod is twisted, and the H-shaped slot rod is wound by the winding device while deforming the groove of the H-shaped slot rod into a spiral groove. A method for forming an H-shaped slot rod of an optical fiber cable.