JP5304608B2 - Electric wire manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an electric wire which is made in a narrow diameter without having uneven thickness of an outer cover while securing excellent wear resistance. <P>SOLUTION: In the method for manufacturing an electric wire 1 where the outer cover 7 made of a resin R is coated on a shield core 8 while the resin R is pulled out from a resin passage 13 between a point 12 and a die 13 and an outer diameter of the outer cover 7 is 0.25 mm or below and a ratio of an outer diameter of the shield core 8 to the outer diameter of the outer cover 7 is 1.15 or below, a difference between an inner diameter of the die and an outer diameter of the point is set at 0.5 mm or more, a melt-flow rate of the resin R is set at 50g/10 minutes or more, and a pulling-out balance is set at 0.99-1.10. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing an electric wire whose outer periphery is covered with a jacket.

  Insulated electric wires and coaxial electric wires having an outer sheath formed of ETFE (tetrafluoroethylene-ethylene copolymer) are known. For example, on a central conductor in which a continuous sinusoidal wave having a pitch of 3.0 mm and a wave height of 0.65 mm is formed on a # 28 silver-plated copper wire according to the AWG (American Wire Gauge) standard, a thickness of 0.13 mm × A first porous PTFE tape having a porosity of 0.8% having a width of 0.8 mm is spirally wound at a pitch of 3.0 mm, and a second porosity having a porosity of 0.13 mm and a width of 2 mm and having a porosity of 75% is further provided thereon. The porous PTFE tape is wound in a spiral manner with a pitch of 5.5 mm and the winding direction opposite to that of the first tape to form a porous tape wound insulating layer. It is known that a 40% 0.06 mm tin-plated copper wire horizontal winding shield is applied and an ETFE extrusion coating layer is applied to the outer periphery thereof (see, for example, Patent Document 1).

Further, it has been shown that a resin such as ETFE can be used as a resin for a coating layer in an ultrafine insulated wire having a conductor core wire and a coating layer coated by extruding a resin around the conductor core wire ( For example, see Patent Document 2).
It is also known to extrude and coat a resin with a draw ratio as a molding condition of 100 (see Non-Patent Document 1).

JP-A-9-259657 JP 2004-56302 A

Polyflon Handbook Daikin Industries, Ltd. Revised December 1983

  In electronic devices such as portable terminals, small video cameras, and medical devices, in order to further reduce the size and thickness of the devices, the casings and components that are moved relative to each other are electrically connected to each other to bend, twist, or slide. It is desired to further reduce the diameter of the moving electric wire, and it is conceivable to reduce the thickness of the outer sheath of the electric wire.

Patent Documents 1 and 2 disclose that ETFE is used as a resin material for the outer sheath of an electric wire, but it has been difficult to coat thinly by extrusion coating under general molding conditions.
In addition, when the outer cover is covered with a thin wall, uneven thickness may occur in the outer cover. In such a case, a withstand voltage failure occurs in the thin part. Further, when the resin is colored by mixing a pigment, the color of the internal electric wire emerges in a thin portion due to the uneven thickness, which causes a hue failure.

  An object of the present invention is to provide a method of manufacturing an electric wire having a small diameter without uneven thickness of the outer jacket.

The method of manufacturing an electric wire according to the present invention that can solve the above-described problem is to coat the outer cover made of the resin on the core portion while drawing the resin from the resin flow path between the point and the die. A manufacturing method for manufacturing an electric wire having a diameter of 0.25 mm or less and a ratio of an outer diameter of the jacket to an outer diameter of the core portion of 1.15 or less,
The difference between the inner diameter of the die and the outer diameter of the point is 0.5 mm or more, the melt flow rate of the resin is 50 g / 10 min (temperature 372 ° C., load 5 kg) or more, and the draw-down balance is 0.99 or more 1 10 or less.

  Further, in the method for producing an electric wire of the present invention, the resin used for the jacket is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, a perfluoromethyl vinyl ether copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer. , Tetrafluoroethylene-ethylene copolymer, polyether ether ketone, polyphenylene sulfide, and polyimide are preferable.

  According to the method of manufacturing an electric wire of the present invention, it is possible to cover the outer cover while minimizing the influence of the deviation between the die and the point, the uneven thickness of the outer cover is suppressed as much as possible, and the pin on the outer cover due to the uneven thickness It is possible to smoothly manufacture a thinned electric wire that does not generate holes. In addition, even when a pigment is mixed into the resin and the outer jacket is colored, an electric wire free from a hue defect due to uneven thickness of the outer jacket can be manufactured.

It is an example of embodiment of the electric wire which concerns on this invention, and is the perspective view of the edge part which exposed each member of the electric wire in steps. It is sectional drawing of the electric wire of FIG. It is sectional drawing which shows a mode that the outer sheath of the electric wire of FIG. 1 is extrusion-molded. (A) is AA sectional drawing in FIG. 3, (b) is BB sectional drawing in FIG.

Hereinafter, an example of an embodiment of a manufacturing method of an electric wire concerning the present invention is described with reference to drawings.
As shown in FIGS. 1 and 2, the electric wire 1 is a coaxial electric wire having a center conductor 2 and an outer conductor 6.
In the electric wire 1, a central conductor 2 is disposed at the center, an insulator 4 is formed around the central conductor 2, and an external conductor 6 is disposed around the insulator 4. The electric wire 1 is configured by covering a shield core (core portion) 8 including a center conductor 2, an insulator 4, and an outer conductor 6 with a jacket 7.

The center conductor 2 is constituted by using a plurality of thin conductive metal wires. In the present embodiment, seven ultrafine copper alloy wires 3 are used and six copper alloy wires 3 are twisted around one copper alloy wire 3.
The copper alloy wire 3 is formed from, for example, a copper alloy containing 0.1 wt% or more and 10 wt% or less of silver, and the wire diameter thereof is set to 0.010 mm or more and 0.025 mm or less. The copper alloy wire 3 has a plated layer of tin, silver or nickel formed on the surface.
For example, the center conductor 2 obtained by twisting copper alloy wires 3 having a silver concentration of 0.1 to 5% by weight has a tensile strength of 600 MPa or more and a conductivity of 65% IACS or more.

  The insulator 4 is made of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), which is a fluororesin, and has an outer diameter of about 0.07 to 0.20 mm.

The outer conductor 6 is braided or laterally wound using a plurality of conductive metal thin wire rods (for example, tin-plated copper alloy wires), and is provided so as to cover the periphery of the insulator 4.
The outer conductor 6 may be, for example, a metal tape vertically attached or spirally wound around the outer periphery of the insulator 4.
In the case of horizontal winding or braiding, the wire is a copper wire or a copper alloy wire (tin copper alloy), and the thickness (diameter) is 0.01 to 0.04 mm.
When using a metal tape (there is a metal layer on the resin tape), the thickness of the resin tape is about 2 to 20 μm and the metal layer (copper or aluminum) is 0.1 to 20 μm.

  Examples of the resin that is provided around the shield core 8 and forms the outermost layer 7 of the electric wire 1 are PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), MFA (perfluoromethyl vinyl ether copolymer). ), FEP (tetrafluoroethylene-hexafluoropropylene copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), PEEK (polyetheretherketone), PPS (polyphenylene sulfide), PI (polyimide) It is used. By using these resins, it is possible to provide an electric wire 1 suitable for wiring to a narrow accommodation space in order to electrically connect the casings that are relatively moved such as rotating and sliding.

  In the electric wire 1, the outer diameter of the outer sheath 7 is 0.25 mm or less, and the ratio of the outer diameter of the outer sheath 7 to the outer diameter of the shield core 8 is 1.15 or less. If the outer diameter of the outer cover 7 is 0.25 mm, the thickness of the outer cover 7 is 0.016 mm or less, and if the outer diameter of the outer cover 7 is 0.22 mm, the thickness of the outer cover 7 is 0. 014 mm or less.

  The electric wire 1 having the above configuration is used in an electronic device such as a portable terminal, a small video camera, or a medical device, and is also used as an electric wire that bends, twists, or slides.

When terminal processing is performed to connect the electric wire 1, first, the outer sheath 7 of the electric wire 1 is cut at a position away from the end portion by a predetermined distance, and the end portion side is pulled out and removed.
Thereafter, the outer conductor 6 is cut at a position closer to the end portion by a predetermined length than the cutting position of the outer jacket 7, and the outer conductor 6 on the end side is pulled out and removed.
Thereafter, the insulator 4 is further cut at a position closer to the end, and the end-side insulator 4 is pulled out and removed.

Next, a method for manufacturing the electric wire 1 will be described.
First, seven copper alloy wires 3 having a very small diameter made of a copper alloy containing 0.1 wt% or more and 10 wt% or less of silver are twisted to form the center conductor 2. As the copper alloy wire 3, for example, a silver copper alloy having a silver concentration of 0.6% by weight is used. The tensile strength of the central conductor is 600 MPa or more, and the conductivity is 85% IACS or more. When the silver concentration is 5% by weight, the tensile strength of the center conductor 2 is 120 MPa or more, and the conductivity is 65% IACS or more and 80% IACS or less.
Then, the outer periphery of the central conductor 2 is extruded and covered with PFA serving as the insulator 4.
The insulator 4 may be configured by winding a fluororesin tape such as PTFE (polytetrafluoroethylene).

  For example, seven conductors (silver copper alloy wires) having a diameter of 0.1 to 5% by weight and having a diameter of 0.025 mm are twisted to form the center conductor 2 having a diameter of 0.075 mm. Then, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) is extruded and coated to form an insulator having an outer diameter of 0.22 mm, for example. A conductor having a smaller diameter and a smaller conductor thickness may be used.

Next, the outer conductor 6 is provided on the outer periphery of the insulator 4 by horizontally winding a plurality of thin conductive metal wires.
After that, the outer conductor 6 is coated on the outer periphery with a resin to be the outer cover 7 to form the outer cover 7. Thereby, it is set as the electric wire 1 whose outer diameter is 0.25 mm or less.
The outer jacket 7 may be formed after a resin tape such as PET is wound around the outer conductor 6 as a press roll.

  In order to form the outer cover 7 on the shield core 8 by extrusion-coating the resin, by selecting a die and a point used for extrusion molding, extrusion coating is performed with the molding conditions as predetermined conditions.

Here, FIG. 3 and FIG. 4 show the state of extrusion molding of the outer cover 7 by pulling down.
Resin R is supplied to the resin flow path 13 between the die 11 and the point 12 constituting the extruder. The end of the die 11 and the end of the point 12 are combined so that they are on the same plane. The shield core 8 in which the outer conductor 6 is wound around the through hole 14 is passed through the center of the point 12. The resin R pushed out from the discharge port 15 which is the outlet between the die 11 and the point 12 does not immediately contact the shield core 8, but gradually becomes thinner and contacts the shield core 8 at a point away from the outlet. And coated.

  At the time of extrusion molding by pulling down, the difference between the inner diameter of the die 11 and the outer diameter of the point 12 is 0.5 mm or more, and in this state, the melt flow rate (MFR) is 50 g / 10 minutes (temperature 372 ° C., load 5 kg). ) Resin R is supplied. At this time, the withdrawal balance DRB that is the degree of similarity between the shape between the die 11 and the point 12 and the shape of the outer cover 7 is set to 0.99 or more and 1.10 or less. The withdrawal balance DRB is obtained by “(die inner diameter × shield core diameter) / (wire finished diameter × point outer diameter)”. As shown in FIG. 4, when the point outer diameter A, the die inner diameter B, the shield core diameter a, and the electric wire finished outer diameter b, the ratio of A / B and = a / b is the withdrawal balance DRB. The withdrawal balance DRB is “DRB = (B × a) / (b × A)”.

  Here, it is difficult to combine the die 11 and the point 12 completely concentrically, and a slight deviation occurs. In the case where the discharge port 15 of the resin flow path 13 between the die 11 and the point 12 is large, even if the center of the die and the point is slightly shifted, uneven thickness hardly occurs, but the discharge port 15 of the resin flow path 13 is small. Then, the thickness of the outer cover 7 is uneven due to the influence of the deviation between the die 11 and the point 12.

  In this embodiment, the difference between the die inner diameter B and the point outer diameter A is 0.5 mm or more, the melt flow rate of the resin R is 50 g / 10 min or more (temperature 372 ° C., load 5 kg), and the withdrawal balance DRB is 0. Since the outer cover 7 is covered with the shield core 8 in the range of .99 to 1.10, the influence of the deviation between the die 11 and the point 12 can be suppressed as much as possible.

Further, when the drawing ratio DDR required by “(die inner diameter) ² − (point outer diameter) ² / (wire finished diameter) ² − (shield core diameter) ² ” is increased, the shear stress applied to the resin R decreases. As a result, the viscosity increases, the fluidity decreases, the follow-up stability of the resin R to the shield core 8 deteriorates, and good coating cannot be performed. Therefore, the withdrawal ratio DDR is usually 50 to 100. However, in the present invention, the difference between the die inner diameter B and the point outer diameter A is 0.5 mm or more, the melt flow rate of the resin R is 50 g / 10 minutes (temperature 372 ° C., load 5 kg) or more, and the withdrawal balance DRB is 0. By setting the value to .99 or more and 1.10 or less, the drawing ratio DDR is set to 300 or more without difficulty, and a thin outer jacket 7 can be realized.

  Therefore, the outer diameter of the jacket 7 is 0.25 mm or less, the ratio of the outer diameter of the jacket 7 to the outer diameter of the shield core 8 is 1.15 or less, and the uneven thickness of the jacket 7 is suppressed as much as possible. The obtained electric wire 1 can be manufactured. Accordingly, the occurrence of pinholes in the outer cover 7 due to uneven thickness is eliminated, the breakdown pressure performance of the outer cover 7 is improved, and a hue failure due to uneven thickness when a pigment is mixed into the resin R and the outer cover 7 is colored. It is possible to manufacture a wire 1 that is not present.

  According to the above-described wire manufacturing method, the outer diameter of the jacket 7 is reduced without unevenness, and it is suitable for wiring to a narrow housing space in order to electrically connect between relatively moved casings such as rotation and sliding. The electric wire 1 can be manufactured smoothly.

  In the above-described embodiment, the electric wire 1 including the coaxial electric wire having the structure in which the center conductor 2, the insulator 4, the outer conductor 6, and the outer jacket 7 are sequentially laminated in a coaxial manner is described as an example. If it is an electric wire covered with, it is not limited to a coaxial electric wire, but can also be applied to an insulated electric wire in which the periphery of a conductor is covered with a jacket.

  For example, a conductor having a wire diameter of 0.217 mm is formed by twisting an element wire such as a tin-plated copper alloy, and an outer sheath 7 is formed by extruding the outer periphery of the resin R to obtain an outer diameter of 0.25 mm or less. An insulated wire may be used.

  The electric wires of Examples 1 to 3 and Comparative Examples 1 to 3 in which the outer sheath was coated under various different molding conditions were manufactured, and the thickness deviation rate of the outer sheath of each electric wire was measured and evaluated. The molding conditions and evaluation results are shown in Table 1. The uneven thickness ratio is the minimum thickness / maximum thickness.

(Evaluation results)
Examples 1-3 in which the difference between the inner diameter of the die and the outer diameter of the point was 0.5 mm or more, the melt flow rate of the resin was 50 g / 10 min or more, and the draw-down balance was 0.94 or more and 1.10 or less In addition, the thickness ratio of the outer jacket became 90% or more, and it was possible to manufacture an electric wire in which the shield core was covered with the outer jacket having a uniform thickness.

  On the other hand, in Comparative Example 1, since the melt flow rate was set to 45 g / 10 minutes which is smaller than 50 g / 10 minutes, the resin was not smoothly supplied to the shield core, and the follow-up stability was lowered to the shield core. The application of the resin was cut off.

  Further, in Comparative Example 2, the difference between the inner diameter of the die and the outer diameter of the point was set to 0.3 mm or less, which is smaller than 0.5 mm. As a result, a large thickness deviation occurred in the outer jacket.

  Further, in Comparative Example 3, the withdrawal balance was 1.14 that was out of the range of 0.99 or more and 1.10 or less, so the withdrawal balance was too large, and the resin did not smoothly follow the shield core, and the shield The application of resin to the core has been cut off.

1: electric wire, 7: jacket, 8: shield core (core part), 11: die, 12: point, 13: resin flow path, R: resin

Claims (2)

The core portion is coated with a jacket made of the resin while pulling the resin from the resin flow path between the point and the die, and the outer diameter of the jacket is 0.25 mm or less, and the outer diameter of the core portion is A manufacturing method for manufacturing an electric wire having an outer diameter ratio of a jacket of 1.15 or less,
The difference between the inner diameter of the die and the outer diameter of the point is 0.5 mm or more, the melt flow rate of the resin is 50 g / 10 min or more, and the draw-down balance is 0.99 or more and 1.10 or less. A method for manufacturing an electric wire. It is a manufacturing method of the electric wire according to claim 1,
Resin used for the jacket is tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, perfluoromethyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyether ether ketone, polyphenylene sulfide, polyimide. A method for producing an electric wire, which is any one of the above.

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