WO2010137700A1

WO2010137700A1 - Method for manufacturing electric wire

Info

Publication number: WO2010137700A1
Application number: PCT/JP2010/059130
Authority: WO
Inventors: 達則林下; 宏和高橋; 正道庭田
Original assignee: 住友電気工業株式会社
Priority date: 2009-05-29
Filing date: 2010-05-28
Publication date: 2010-12-02
Also published as: JP5533672B2; KR20120027086A; JPWO2010137700A1; CN102084437B; CN102084437A

Abstract

Disclosed is a method for manufacturing an electric wire, which can economically manufacture the wire having an air gap formed stably for an insulator covering a conductor and exhibiting good transmission efficiency. The circumference of a central conductor (12) that is drawn out from an insertion hole (44) formed in the center of a point (41) is covered with an insulator (13) consisting of resin (R) by extruding the resin (R) to annular extrusion channels (51, 52) consisting of the gap between a die (31) having a truncated conical inner circumferential surface (32) and the point (41) having a truncated conical outer circumferential surface (42) thus manufacturing an electric wire (11). Three or more tubular bodies (45) extending through the extrusion channels (51, 52) along the extrusion direction are provided on the outer circumferential surface (42) of the point (41) at equally-spaced intervals in the circumferential direction, and the resin (R) is extruded to the extrusion channels (51, 52) thus forming a plurality of air gaps (14) in the resin (R) continuously in the longitudinal direction, at intervals in the circumferential direction, by the air flowing from the tubular bodies (45).

Description

Electric wire manufacturing method

This invention relates to the manufacturing method of the electric wire by which the outer periphery of the conductor was coat | covered with the insulator which consists of resin.

The use frequency band of electric wires has been expanded to a few GHz band, and there is a demand for a wire with a low dielectric constant of the insulator portion. In order to reduce the dielectric constant, a technique for forming a hollow portion in an insulator is a die including a plurality of the same openings arranged symmetrically around a longitudinal axis, and each cross section of the openings is It is known that it has a substantially T-shape, each horizontal bar of T is bent around the vertical axis, all belong to the same cylinder, and the extension lines of the vertical bars use dies that intersect each other on the vertical axis (for example, Patent Document 1). And by using this device, when the molded insulating material is stretched before being superimposed on the conductor, this material stretches the T bars to contact each other at the die exit. Under pressure, this forms a sheath having a plurality of vesicles around the conductor.

In addition, the center hole for inserting the inner conductor, the inner annular hole installed adjacent to the outer periphery of the center hole, a plurality of linear holes extending radially from the outer periphery of the inner annular hole, and the outer ends of the linear holes are connected. Using a die having an outer annular hole, the resin melted from each hole is extruded substantially vertically downward while the inner conductor is inserted into the center hole, and the inner annular part covering the inner conductor, and the inner annular part Manufacturing to form an insulating coating layer including a plurality of radially extending rib portions, an outer annular portion connecting outer ends of the rib portions, and a plurality of hollow portions surrounded by the inner and outer annular portions and the rib portions A method is also known (see, for example, Patent Document 2).

Japanese patent publication: JP-A-10-116527 Japanese Patent Publication: JP 2008-243720 A

In the manufacturing method of Patent Document 1, vesicles are formed by the insulating materials overlapping each other at the end surfaces of the horizontal bars of T. Therefore, if conditions such as the viscosity of the insulating material fluctuate, the overlapping of the end surfaces is defective. There is a possibility that voids formed of stable vesicles may not be formed.

In the manufacturing method of Patent Document 2, an inner annular hole installed adjacent to the outer periphery of the insertion hole of the inner conductor, a plurality of linear holes extending radially from the outer periphery of the inner annular hole, and the outer ends of the linear holes are connected. A very complex die having an outer annular hole is required. In addition, it is extremely difficult to form such a die with high accuracy, and the formed gap portion becomes unstable and the size thereof varies.
Moreover, in the manufacturing method of the said patent documents 1 and 2, a complicated-shaped die | dye is needed for every manufacture of the electric wire from which the outer diameter of an insulator, the magnitude | size of a space | gap part, etc. differ. Even if such a die can be manufactured, the processing cost is high and the cost is high.

An object of the present invention is to provide an electric wire manufacturing method capable of economically manufacturing an electric wire with good transmission efficiency in which a gap is stably formed in a length direction with respect to an insulator covering a conductor. It is in.

The method of manufacturing an electric wire according to the present invention that can solve the above-described problem has a die having an inner peripheral surface in a shape in which a cylinder is connected to a truncated cone portion and an outer peripheral surface in a shape in which the cylinder is connected to a truncated cone portion A method of manufacturing an electric wire that extrudes and pulls down a resin to an annular extrusion flow path composed of a gap with a point, and covers the resin around a conductor drawn out from an insertion hole formed at the center of the point,
Three or more cylinders extending into the extrusion flow path along the extrusion direction are provided at equal intervals in the circumferential direction on the outer peripheral surface of the truncated cone portion of the point, and the resin is placed around the cylinder. By flowing, a plurality of gaps continuous in the longitudinal direction are formed in the resin at intervals in the circumferential direction. The number of cylinders is preferably 6 or more and 9 or less.

Further, in the method of manufacturing an electric wire according to the present invention, a communication hole that penetrates the cylindrical body and the truncated cone portion of the point is provided in the cylindrical body, and the air naturally flows in from the point through the communication hole. It is preferable to extrude the resin.
Alternatively, it is preferable to extrude the resin while supplying gas to the communication hole.

In the method for producing an electric wire of the present invention, it is preferable that the resin is extrusion coated with a draw ratio of 400 or more and 2000 or less.

According to the method for manufacturing an electric wire of the present invention, three or more cylinders extending in the extrusion flow path along the extrusion direction are provided on the outer peripheral surface of the point at equal intervals in the circumferential direction, and the resin is provided. By extruding to the extrusion flow path, a plurality of voids continuous in the longitudinal direction are formed in the resin at intervals in the circumferential direction by the gas flowing in from the cylindrical body. As a result, it is possible to economically manufacture an electric wire with good transmission efficiency in which a plurality of voids are stably formed in the insulator covering the conductor at intervals in the circumferential direction and the dielectric constant is reduced.

It is sectional drawing of the embodiment of the electric wire manufactured by the manufacturing method of the electric wire which concerns on this invention. It is sectional drawing of a part of die | dye used for the manufacturing method of the electric wire of this embodiment, and a point. It is a one part perspective view of the point used for the manufacturing method of the electric wire of this embodiment. It is sectional drawing of the combination of the die | dye and point which show the extrusion coating process in the manufacturing method of the electric wire of this embodiment. It is a figure which shows another form of the extruder used for the manufacturing method of the electric wire of this embodiment.

Hereinafter, an example of an embodiment of a manufacturing method of an electric wire concerning the present invention is described with reference to drawings.
First, the electric wire manufactured by the manufacturing method of the electric wire of this embodiment is demonstrated.

In FIG. 1, a coaxial wire will be described as an example.
The electric wire 11 has a shape in which a central conductor 12 is covered with an insulator 13, an outer conductor 15 is disposed on the outer periphery of the insulator 13, and the outer side thereof is protected by a jacket 16. The void portion 14 is provided. In addition, there is no design gap between the center conductor 12 and the insulator 13 and between the center conductor 12 and the outer conductor 15.

The center conductor 12 is formed of a single wire or a stranded wire made of an annealed copper wire or a copper alloy wire plated with silver or tin. In the case of a stranded wire, for example, one having an outer diameter of 0.075 mm (equivalent to AWG # 42) twisted from seven strand conductor diameters of 0.025 mm, or one having a strand conductor diameter of 0.127 mm. Seven twisted outer diameters of 0.38 mm (equivalent to AWG # 28) are used.

The outer conductor 15 has a silver-plated or tin-plated annealed copper wire or copper alloy wire having the same thickness as that of the wire conductor used for the center conductor 12 and is wound horizontally or braided on the outer periphery of the insulator 13. Formed. Furthermore, in order to improve a shield function, it is good also as a structure which attaches a metal foil tape side by side. The jacket 16 is formed by extruding a resin material such as a fluororesin, a polyolefin-based resin, or vinyl chloride, or winding a resin tape such as a polyester tape.

The insulator 13 is formed by extrusion molding using a thermoplastic resin such as polyethylene (PE), polypropylene (PP), or a fluororesin. Examples of fluororesin materials include PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), and ETFE (tetrafluoroethylene / ethylene copolymer). , Etc. are used. Polyphenylene sulfide resin (PPS) can also be used.

The outer diameter D1 of the insulator 13 is desirably about D2 × (2.2 to 3.0), where the conductor diameter of the central conductor 12 is D2. For example, when the conductor diameter of the central conductor 12 is 0.38 mm (AWG # 28), the outer diameter of the insulator 13 is set to 0.84 mm to 1.1 mm. When the conductor diameter of the central conductor 12 is thinner than AWG # 42, the capacitance of the insulator 13 needs to be low depending on the application. In this case, the outer diameter D1 of the insulator 13 is set to D2 × ( 2.2 to 3.6) is desirable. For example, when the conductor diameter of the center conductor 12 is 0.075 mm, the outer diameter of the insulator 13 is set to 0.17 mm to 0.27 mm. In addition, in this invention, the outer diameter of the insulator 13 is made into the object formed by 1.1 mm or less.

The electric wire 11 having this dimension is often used for antenna wiring, wiring for connecting an LCD and a CPU, and as a multi-core electric wire for connecting a sensor and a device in a mobile phone or a notebook personal computer. With the downsizing and thinning of the device, it is required to reduce the diameter of the coaxial cable. The coaxial cable needs to have a predetermined impedance (50Ω, 75Ω, or 80Ω to 90Ω), and has a diameter as small as possible. For this purpose, it is necessary to reduce the dielectric constant of the insulator 13 between the center conductor 12 and the outer conductor 15. In the present embodiment, the void portion 14 is provided in the insulator 13, and the total void ratio of all the void portions 14 (= (sum of cross-sectional areas of the void portions 14) / {(cross-sectional area of the insulator 13) + (Sum of the cross-sectional area of the gap portion 14)}) is set to 43% or more, thereby realizing a reduction in diameter within the above-mentioned range.

Since the electric wire 11 has a small diameter and the insulator 13 is thin, the electric wire 11 may not be able to withstand external pressure or bending applied to the electric wire 11. Therefore, in the thin electric wire 11 targeted by the present embodiment, the size of each gap portion 14 provided in the insulator 13 becomes a problem. This is a problem that is not found in larger diameter wires.
When the ratio of the diameter of the insulator 13 to the diameter of the central conductor 12 is 2.4 to 2.7 times, 7 to 9 gaps 14 are arranged, and the porosity of one gap 14 is 6 It is preferable to set it to 8% or less. In particular, it is preferable that the number of the void portions 14 is 8, and the porosity of the insulator 13 is 43% to 54%.
When the ratio of the diameter of the insulator 13 to the diameter of the central conductor 12 is 3.2 to 4.0 times, the number of the gap portions 14 is 6, and the void ratio of one gap portion 14 is 9.0 to 10%. It is preferable that
In the present embodiment, by setting the porosity per piece to the above-mentioned size, sufficient durability is realized with an electric wire of this size. The air gap portion 14 is formed in a circular cross section (perfect circle, ellipse) and is evenly arranged around the central conductor 12. For example, when the gap 14 is formed in a perfect circle and the inner diameter is D3, the ratio of one gap 14 to the insulator 13 is expressed by the following equation.
{(D3 / 2) ² × π} / {(D1 / 2) ² × π− (D2 / 2) ² × π}

When the ratio of the diameter of the insulator 13 to the diameter of the central conductor 12 is larger than 4 times, the number of the gap portions 14 can be further reduced to 3 or more.

Next, a method for manufacturing the above electric wire will be described.

As shown in FIGS. 2 and 3, the extruder 30 used for manufacturing the electric wire 11 includes a die 31 and a point 41.
The die 31 has a truncated cone portion 32 having an inner peripheral surface having a truncated cone shape, and a cylindrical extrusion hole 33 is formed at the center thereof. The diameter of the extrusion hole 33 is constant in the length direction. The inner peripheral surface of the die 31 has a shape in which a cylinder is joined to a truncated cone.

The point 41 has a truncated cone part 42 whose outer peripheral surface has a truncated cone shape, and a cylindrical part 43 is formed at the tip thereof. Further, an insertion hole 44 is formed at the center of the point 41, and the central conductor 12 is inserted into the insertion hole 44 and drawn forward.

The die 31 and the point 41 are arranged such that the truncated cone part 32 and the truncated cone part 42 form a predetermined annular gap. The gap between the truncated cone part 32 of the die 31 and the truncated cone part 42 of the point 41 and the gap between the extrusion hole 33 of the die 31 and the cylindrical part 43 of the point 41 are formed into

extrusion channels

51 and 52 that communicate with each other. ing. Then, the molten resin R forming the insulator 13 is introduced from the rear side into the extrusion flow path 51, fed into the extrusion flow path 52, and pushed out from the extrusion hole 33.
The cylindrical portion 43 of the point 41 has a plurality of cylindrical cylindrical bodies 45 arranged concentrically at equal intervals in the circumferential direction, and extends along the extrusion direction of the resin R. 43 is inserted into the extrusion hole 32 of the die 31. The tip of the cylinder 45 is on the same surface as the tip of the cylindrical portion 43 or in the vicinity thereof. The cylindrical body 45 exists in the

extrusion flow paths

51 and 52, and the molten resin R does not flow through the portions.

These cylinders 45 have communication holes 46, and the communication holes 46 pass through the cylindrical portion 42 and are opened on the inner surface of the point 41. The inner surface of the point 41 does not form a closed space and communicates with the outside of the extruder 30.

When covering the center conductor 12 with the insulator 13 using the extruder 30, the center conductor 12 is inserted into the insertion hole 44 of the point 41 as shown in FIG. 4.
Then, the molten resin R is pushed out from the rear side to the extrusion channel 51 while pulling out the central conductor 12 from the extruder 30. The resin R is extruded from the extrusion hole 33 through the

extrusion channels

51 and 52, and is stretched to gradually reduce its diameter, and the resin R is placed on the center conductor 12 at a position away from the outlet of the extrusion hole 33 by a certain distance. To cover the central conductor 12. That is, the resin R is coated as the insulator 13 on the outer periphery of the center conductor 12 by pulling down. At this time, the withdrawal ratio is 400 or more and 2000 or less.

Here, this drawing ratio is defined as follows. The inner diameter of the extrusion hole 33 of the die 31 is Dd, and the outer diameter of the cylindrical portion 43 of the point 41 is Dp. From the relationship, it is expressed by the following formula.
^{^{^{(Dd 2 -Dp 2) / (}}} D1 2 -D2 2)

At this time, the resin R forming the insulator 13 becomes a flow surrounding the cylindrical body, and the gap portion 14 is formed. The communication holes 46 of the plurality of cylinders 45 extending along the extrusion direction from the point 41 communicate with the atmosphere outside the point, and air is drawn into the gap portion 14 from the communication hole 46. As a result, a plurality of gaps 14 that are continuous in the longitudinal direction are formed in the insulator 13 at intervals in the circumferential direction.

Next, the outer conductor 15 is provided on the outer periphery of the insulator 13 by braiding or transversely winding a plurality of thin wires of conductive metal. A metal foil may be wound around the insulator 13 or vertically attached as an external conductor. Alternatively, an external conductor may be laminated by sandwiching an insulator between two metal foils.
Thereafter, the outer sheath 15 is formed by coating the outer circumference of the outer conductor 15 with a resin to be the outer sheath 16 or winding an insulating tape to form the outer sheath 16.

According to the electric wire 11 manufactured as described above, the number of the gaps 14 formed in the insulator 13 is 7 to 9 (eight in this embodiment), and the porosity of one gap 14 is 6.8%. By setting it as the following, even if the porosity which puts all the cavity parts 14 together is 43% or more, it is hard to be crushed with respect to an external pressure or a bending, and the stable transmission characteristic can be ensured. When the number of the gap portions 14 is 6, the void ratio of one gap portion 14 is set to 9.0 to 10%, and the void ratio of all the gap portions 14 is set to 54% or more so that the external pressure and the bending can be reduced. On the other hand, it is difficult to be crushed and stable transmission characteristics can be secured.

And the electric wire 11 manufactured in this way is used in the state of the electric wire 11, or is used as a multi-core electric wire in a tape form by bundling a plurality of wires in parallel.

As described above, in the method of manufacturing an electric wire according to the present embodiment, three or more (eight in the present embodiment) cylinders 45 extending in the

extrusion flow paths

51 and 52 along the extrusion direction are point 41. Are provided at equal intervals in the circumferential direction on the outer peripheral surface 42 of the resin, and the resin R is pushed out to the

extrusion flow paths

51 and 52, thereby creating a flow of the resin R around the cylinder 45 and in a portion downstream of the cylinder 45. A gap 14 that is continuous in the longitudinal direction is formed. The gaps 14 are formed at substantially equal intervals in the circumferential direction in the cross section perpendicular to the length direction of the insulator 13 according to the location where the cylinder 45 is located. Since the plurality of gaps 14 are formed in the insulator, the dielectric constant of the insulator 13 is reduced.
Thus, the electric wire 11 in which the dielectric constant of the insulator 13 is reduced can be easily manufactured.

The present invention uses an extruder 30 including a general die 31 having a frustoconical inner peripheral surface 32 and a point 41 having a simple structure in which a plurality of cylindrical bodies 45 are extended from the outer peripheral surface 42. . Compared with the case of using a die in which extrusion holes are formed in a complicated shape in order to form a void portion, the point 41 of the present invention can be processed with high accuracy, so that the void portion to be molded has a stable size. Therefore, no variation occurs. Moreover, since processing is easy, equipment costs can be reduced. That is, the low-capacity electric wire 11 in which the gap portion 14 is formed in the insulator 13 can be manufactured economically.

In addition, by changing the combination of the die 31 and the point 41, the wires 11 having the number and size of the gaps 14 or various diameters can be easily manufactured.
Thereby, the ratio of the space | gap part 14 in the insulator 13 and the thickness of the insulator 13 can be made into a desired thing.

In addition, in a thin wire having an outer diameter of the insulator 13 of 1.1 mm or less by making the draw ratio when the resin R is extrusion coated on the center conductor 12 to be a draw ratio as large as 400 or more and 2000 or less. The insulator 13 having the gap portion 14 can be satisfactorily covered on the outer periphery of the central conductor 12.
The cylinder 45 is not limited to a cylinder, and may have an elliptical cross section or a square shape. In this case, the cross section of the formed void is elliptical.

Moreover, in the said embodiment, at the time of the extrusion covering of the resin R to the center conductor 12, air naturally flows in from the point 41 through the communicating hole 46 of the cylindrical body 45 of the point 41, and the space | gap part 14 is formed without being crushed. However, the resin R may be extruded while supplying a gas such as air to the communication hole 46. The insulator 13 can be formed by feeding gas into the gap portion 14 to maintain the shape of the gap portion 14 and pulling the resin R down. If the pressure in the gap portion 14 is excessively positive, the insulator 13 is deformed and deviated from the intended shape, so that the air pressure in the gap portion 14 is increased by 1 to 100 Pa compared to the outside.

In FIG. 5, the structure of the extruder in the case of sending gas into the space | gap part 14 and pressurizing is shown.
In the extruder 30a, a pressure nozzle 55 is connected to the rear end of the point 41. A gas supply pipe 56 is connected to the pressurizing nozzle 55. A pressurized gas (air or the like) is sent from the gas supply pipe 56 through the pressurizing nozzle 55 into the point 14, and the point 14 is set to a positive pressure of 1 to 100 Pa with respect to the surrounding atmospheric pressure (atmospheric pressure). .

Under the conditions shown below, an electric wire having the structure as shown in FIG. 1 was manufactured, and the outer diameter variation and capacitance of the insulator were examined.
(Example 1)
Inner conductor: Twisted wire (corresponding to AWG42) of seven silver-plated silver-copper alloys (silver content 0.6%) with a diameter of 0.025 mm
Insulator: PFA, outer diameter 0.25mm (thickness 0.087mm)
Withdrawal rate: 1310
Pressurization within the point (difference from atmospheric pressure): 4Pa
Insulator capacitance: 60.5 pF
Insulator outer diameter variation: ± 0.006 mm variation (Example 2)
The capacitance of the insulator is 61.2 pF as in Example 1 except that the inside of the point is not pressurized.
Insulator outer diameter variation: ± 0.026mm variation

Example 1 and 2 were compared, and it was confirmed that the outer diameter of the insulator was stabilized and the capacitance of the insulator was reduced by pressurization. It is considered that the space in the insulator increases due to the slight expansion of the gap and the capacitance decreases. In addition, it is considered that when the resin is drawn down, the void portion is slightly positive pressure, so that the resin drawn shape is stabilized and the outer diameter of the insulator is stabilized in the longitudinal direction.

Example 3
Inner conductor: Stranded wire (corresponding to AWG32) in which seven silver-plated annealed copper wires with a diameter of 0.079 mm are twisted together
Insulator: PFA, outer diameter 0.61 mm (thickness 0.185 mm)
Withdrawal rate: 460
Pressurization within the point (difference from atmospheric pressure): 75 Pa
Insulator capacitance: 79.0 pF
Insulator outer diameter variation: ± 0.014 mm variation (Example 4)
The capacitance of the insulator is 84.0 pF as in Example 3 except that the inside of the point is not pressurized.
Insulator outer diameter variation: ± 0.014mm variation

Example 3 and Example 4 were compared, and the effect of reducing the capacitance by pressurization was confirmed. The outer diameter variation of the insulator was almost the same whether or not it was pressurized. In Example 3 and Example 4, the diameter of the electric wire was larger than that in Example 1 and Example 2, and the differential pressure from the atmospheric pressure was increased. In this case, it has been confirmed that the effect of reducing the capacitance by setting the outer diameter variation of the insulator to the same level is great.

Further, the number of cylinders 45 formed at the point 41 is not limited to eight, but may be three or more, and preferably 7-9.

In the above embodiment, the electric wire 11 made of a coaxial electric wire having a structure in which the central conductor 12, the insulator 13, the outer conductor 15, and the outer sheath 16 are sequentially coaxially laminated has been described as an example. As long as it is an electric wire covered with an insulator, it is not limited to a coaxial electric wire.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on May 29, 2009 (Japanese Patent Application No. 2009-130088), the contents of which are incorporated herein by reference.

DESCRIPTION OF SYMBOLS 11: Electric wire, 12: Center conductor (conductor), 13: Insulator, 14: Space | gap part, 31: Dice, 32: Inner peripheral surface, 41: Point, 42: Outer peripheral surface, 44: Insertion hole, 45: Cylindrical body 51, 52: extrusion flow path, R: resin

Claims

Resin is extruded and pulled down into an annular extrusion flow path consisting of a gap between a die having an inner peripheral surface shaped like a cylinder connected to a truncated cone portion and a point having an outer peripheral surface shaped like a cylinder joined to a truncated cone portion A method of manufacturing an electric wire covering the resin around a conductor drawn out from an insertion hole formed at the center of the point,
Three or more cylinders extending into the extrusion flow path along the extrusion direction are provided at equal intervals in the circumferential direction on the outer peripheral surface of the truncated cone portion of the point, and the resin is placed around the cylinder. A method for producing an electric wire, wherein a plurality of voids continuous in a longitudinal direction are formed in the resin at intervals in a circumferential direction by flowing.
It is a manufacturing method of the electric wire according to claim 1,
The tubular body is provided with a communication hole penetrating the cylindrical body and the truncated cone portion of the point, and the resin is pushed out while air naturally flows from the point through the communication hole. Method.
It is a manufacturing method of the electric wire according to claim 1,
A method of manufacturing an electric wire, wherein a communication hole that passes through the cylindrical body and the truncated cone portion of the point is provided in the cylindrical body, and the resin is extruded while supplying gas to the communication hole.
It is a manufacturing method of the electric wire according to any one of claims 1 to 3,
A method for producing an electric wire, wherein the resin is extrusion coated at a draw ratio of 400 or more and 2000 or less.