JP2005276785A - Coaxial cable and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial cable excellent in closely contacting property, and a manufacturing method of the same. <P>SOLUTION: The coaxial cable 10 is composed of center conductors 12, an insulation cove layer 14, shield conductors 16, and a protection cover layer 18. The cover layer 14 formed so as to cover the outer periphery of the conductors 12 has a ring-shaped part 20 covering the outer periphery of the conductors 12 and three column-shaped parts 22 radially extended from the sing-shaped part 20a in the direction of diameter. The shield conductor 16 is composed of hollow and compressed strand wire. The strand wire is formed into hollow-shape by passing a plurality of elemental wires 26 through a compression dice while twisting them in one direction. At this time, as a part of outer periphery of the elemental wires 26 is deformed and twisted, shield wires tightly contact with each other like a stone fence, and made to have a stable structure (arch structure). At the same time, a part of the insulation cover layer 14 contacting the shield conductor 16 is turned into a deformation part 28 tightly contacting the shield conductor 16 along the inner face shape thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coaxial cable having good and stable electrical characteristics and high-frequency characteristics, and a method for manufacturing the same.

  Recently, coaxial cables are being used for antenna wiring of personal digital assistants, wiring for connecting an LCD and a CPU, etc. in response to an increase in information amount and high-speed transmission. In addition, with the miniaturization and thinning of information terminals and notebook computers, coaxial cables are also required to have high performance, small diameter, and low cost.

  In general, in order to obtain a coaxial cable with good high-frequency characteristics (low transmission loss and low delay time), the dielectric constant of the electrically insulating coating layer formed between the center conductor and the outer shield layer should be as small as possible. It is important to.

If the characteristic impedance is 50Ω (constant value), for example, by reducing the dielectric constant, the inner diameter of the shield layer (the outer diameter of the cable) can be reduced if the center conductor diameter is the same. If the inner diameter (outer diameter of the cable) is made constant, the center conductor diameter can be increased and the transmission loss can be reduced.
Therefore, a low dielectric constant resin such as a fluorine resin or a polyolefin resin is often used for the insulating coating layer, and foaming is often performed in order to reduce the apparent dielectric constant.

  In addition, in coaxial cables, shielding characteristics are also important, not only reducing the impact on the external environment, but also reducing the transmission loss by improving the shielding effect, but if this is simply composed of stranded wires When bent, the stranded wire may open and the shielding characteristics may deteriorate.

  Also, in order to reduce the dielectric constant of the insulating coating layer, increasing the porosity and foaming level, and increasing these (50% or more), the strength of the insulating coating layer decreases, and it is composed of stranded or braided wire When the shielded conductor is covered, it is easily deformed, and as a result, the characteristic impedance varies.

  As a method for solving such a problem, for example, Patent Document 1 discloses a coaxial cable in which an insulating coating layer has a two-layer structure of an insulating layer and a skin layer, and only the insulating layer is made of foamed resin. Proposed.

However, the coaxial cable disclosed in Patent Document 1 has a technical problem described below.
JP 2000-48653 A

  That is, in the coaxial cable disclosed in Patent Document 1, since the insulating coating layer has a two-layer structure, the manufacturing apparatus becomes complicated and the cost increases. There is a shield conductor with a braided structure, but the shield conductor with this structure has a problem that the braiding processing speed is slow and the cost is increased, and a sufficient shielding effect cannot be obtained.

  Therefore, the present inventors have newly developed a coaxial cable for solving such a problem and have already proposed it in Japanese Patent Application No. 2003-350376. The coaxial cable according to this application is a coaxial cable including a central conductor, an insulating coating layer that covers an outer periphery of the central conductor, and a shield conductor that covers an outer periphery of the insulating coating layer. The gist is that the wire is arranged along the outer periphery of the insulating coating layer, and a part of the outer periphery of the strands that are in contact with each other is plastically deformed to form a hollow hollow shape. Yes.

  However, subsequent studies have revealed that the coaxial cable according to this proposal has the following technical problems. The previously proposed coaxial cable includes, as an insulation coating layer, an annular portion that covers the center conductor in an annular shape, and three columnar portions that extend radially outward from the annular portion, and between the compression strands. The structure of the structure in which the hollow part divided by the columnar part is formed is included.

  In the coaxial cable having such a structure, in particular, the compression stranded wire is affected by the dimension of the core (in which the central conductor is covered with an insulating coating layer composed of an annular portion and a columnar portion) inserted therein. Easy, for example, if the outer dimensions of the three columnar parts are larger than the inner diameter of the compression stranded wire, the shape of the compression stranded wire does not become circular, it becomes close to a triangle, the characteristic impedance becomes unstable, In extreme cases, it may not be possible to form a stranded wire in a hollow shape.

  When the outer dimensions of the three columnar portions are smaller than the inner diameter of the compression strand, the shape of the compression strand is maintained well, but the adhesion between the core and the compression strand is almost maintained. When the coaxial cable is terminated, the core comes out of the compression stranded wire and the termination cannot be performed, or the target dimensions are not met, or the cable is bent. The core may jump out of the cut end face.

  For such inconvenience, for example, it is very difficult to finely control the outer dimensions of the core in relation to the inner diameter of the compression stranded wire, and the adhesion between the core and the compression stranded wire is very difficult. It was difficult to keep good.

  Furthermore, when the core is formed of a central conductor and a circular coating layer (not hollow, solid, nor foamed or porous) formed on the outer periphery of the core conductor, the outer diameter of the core is If it is smaller than the inner diameter of the compression stranded wire, there will be a gap between them, the position of the core will fluctuate and the high frequency characteristics will deteriorate, and if the outer diameter of the core is larger than the inner diameter of the compression stranded wire, compression will occur. The compression rate of the stranded wire becomes small, and the outer periphery of the core cannot be completely closed with the compressed stranded wire, so that a sufficient shielding effect cannot be obtained.

  In this case, when the circular coating layer is porous or foamed, the coating layer can be deformed when the compression stranded wire is disposed on the outer periphery of the core, so that the adhesion can be improved to some extent. That's not enough.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a coaxial cable having good adhesion and a method for manufacturing the same.

  In order to achieve the above object, the present invention provides a coaxial cable comprising a central conductor, an insulating coating layer covering an outer periphery of the central conductor, and a shield conductor covering an outer periphery of the insulating coating layer. A plurality of strands are arranged along the outer periphery of the insulating coating layer, and are composed of compression stranded wires formed in a hollow shape by plastic deformation of a part of the outer periphery of the strands that are in contact with each other, The insulating coating layer is configured to closely contact and deform the contact portion with the shield conductor along the inner surface shape of the shield conductor.

  According to the coaxial cable configured in this manner, the compression stranded wires are formed in a hollow shape by plastic deformation of a part of the outer periphery of the strands that are in contact with each other, and the strands of the strands are stone-walled Since the stable structure (arch structure) in close contact with each other is taken, the inside of the stranded wire is hollow.

  A coaxial cable can be obtained by providing an insulation-coated conductor in which the outer circumference of the center conductor having the same outer diameter as the hollow inner diameter is covered with an insulation coating layer in such a compression stranded wire. The coaxial cable has good shielding properties because the strands are in close contact with each other, and also has good flexibility because the strands are joined together but are not integrated.

  In the present invention, since the insulating coating layer is in close contact with and deformed at the contact portion with the shield conductor along the inner surface shape of the shield conductor, the adhesion strength between the insulating coating layer and the shield conductor is large. Become.

  A protective coating layer can be provided on the outer periphery of the seal conductor composed of compression stranded wires, and an electrically insulating thermoplastic resin can be used for the protective coating layer.

  In the coaxial cable of the present invention, since a stable hollow portion can be formed only with a compression stranded wire, the shape of the insulation-coated conductor provided in the inside does not necessarily need to be a circle that contacts all the strands of the compression stranded wire. If a conductor can be located in the center part of a compression strand, the shape can be selected arbitrarily.

  Therefore, the insulating coating layer includes an annular portion that annularly covers the center conductor, and one or more columnar portions extending radially outward from the annular portion, and the compression stranded wire, The hollow part divided by the columnar part can be formed.

  The insulating coating layer includes an inner annular portion that covers an outer periphery of a central conductor, a plurality of connecting portions that extend outward from the inner annular portion, and an outer annular portion that connects the outer peripheral edges of the connecting portions. And the circumferential direction of the gap portion defined by the inner and outer annular portions can be divided by the connecting portion.

  In addition, a structure in which a hollow pipe is twisted around the center conductor, a structure in which an insulating (porous) tape is wound, or a structure in which insulating fibers are knitted may be used.

  The cross-sectional shape of the strand of the hollow compression stranded wire may be circular, rectangular, trapezoidal or the like. In the case of a circular shape, it is advantageous in terms of cost, but as the number increases, it may be difficult to maintain a hollow structure. In such a case, it is desirable to use a rectangular or trapezoidal shape.

  For the insulating coating layer, a low dielectric constant resin such as a fluorine resin, a polyolefin resin, a PEN (polyethylene naphthalate) resin, or an APO (cyclic polyolefin) resin excellent in dielectric constant and heat resistance can be used.

  In particular, in order to reduce loss characteristics, the insulating coating layer preferably has a hollow portion stably provided. In this case, the structure having the columnar portion described above is suitable. When providing the columnar part, it is desirable that the number is 2 to 4 and the hollowness is 50% or more.

  When the hollow ratio is 50% or less, the hollow effect is lowered. Further, the number of columnar portions may be eccentric with one, and even when the number is five or more, the eccentricity prevention effect does not change, and conversely, the hollowness decreases.

  The present invention also relates to a method of manufacturing a coaxial cable including a center conductor, an insulating coating layer, and a shield conductor, and an insulating coating layer formed by extruding a synthetic resin on the outer periphery of the center conductor. A step of obtaining a coated conductor, and the insulating coated conductor is arranged and introduced into the central portion of a collective stranding machine such as a single twist machine via an alignment guide plate provided at the front, and a plurality of strands, Through the alignment guide plate, after evenly arranged on the same circumference along the outer circumference of the insulation coating layer of the insulation coating conductor, while passing a compression die attached to the concentrating port of the assembly stranding machine, By rotating the compression die, a part of the outer circumferences of the strands that are in contact with each other is plastically deformed to form a hollow compressed hollow strand continuously on the outside of the insulation-coated conductor. Above Forming a yield conductor, and heat-softening the insulation coating layer when introducing the insulation coating conductor into the central portion of the assembly stranding machine, heating the compression die to a predetermined temperature, A heating process selected from at least one of heating each of the strands to a predetermined temperature was performed.

  In this manufacturing method, a protective coating layer can be formed of an electrically insulating synthetic resin on the outer periphery of the compression stranded wire after the shield conductor forming step.

  Generally, a stranded wire is manufactured with a single twist machine and a double twist machine. The same applies to the compression stranded wire used in the coaxial cable of the present invention, and a compression die is inserted during the twisting process to produce a hollow compression stranded wire.

  So, first, using a double twist machine, we tried to manufacture a coaxial cable by introducing an insulation coated conductor and a strand for compression stranded wire, but the insulation coated conductor was twisted together with the compression stranded wire, It has been found that a twist similar to that of a compression stranded wire is applied.

  In this case, when a twist is applied to the central conductor of the insulation-coated conductor, when the central conductor is a single wire, undulation occurs and the phenomenon of eccentricity occurs. In the case where the central conductor is a stranded wire, the strands were broken together with the eccentricity and the undulations of the strands. These phenomena affect the stability of the electrical characteristics and high-frequency characteristics of the coaxial cable.

  When a double twist machine is used, twisting is applied in two stages, but the compression die needs to be put in the first stage twisting process. This is because if this is put in the second stage, the variation in the length of the strands of the compression stranded wire cannot be absorbed.

  In this case as well, in the first-stage twisting process, the insulation-coated conductor is gripped by the compression twisted wire, and further the second-stage twist is added, and the length of the compression-twisted wire in the longitudinal direction is reduced by the second-stage twisting. However, since the insulation-coated conductor has a small diameter, it does not shrink as much, and a difference in length occurs. Based on this difference in compression length, undulation is generated in the insulation-coated conductor, and the strands of the compressed stranded wire are scattered, and the insulation-coated conductor is popped out at the time of cutting. Therefore, it is practically difficult to produce a long run by a production method using a double twist machine.

  The insulating coating layer includes an annular portion that covers the center conductor in an annular shape, and one or more columnar portions that extend radially outward from the annular portion, and is partitioned by a columnar portion between the compression strands. In the case of a structure that forms a hollow portion, when a double twist machine is used, since the twist pitch of the columnar portion matches the pitch of the compression strand, a part of the strand of the compression strand is There was a problem of falling between the columnar parts.

  However, according to the method of manufacturing a coaxial cable according to the present invention configured as described above, a single twist machine is used to twist in a single step, so that there is no difference in length between the insulation-coated conductor and the compression stranded wire. . For this reason, the central conductor does not have a backlash, and the insulation covered conductor does not protrude.

  Further, in the manufacturing method according to the present invention, the insulation coating layer is heated and softened when the insulation coating conductor is disposed and introduced in the central portion of the assembly strand wire machine, the compression die is heated to a predetermined temperature, and each of the strands. When heat-softening the insulation coating layer when introducing the insulation coating conductor in the central portion of the collective stranding machine, a heat treatment selected from at least one of heating to a predetermined temperature is performed. When a compression stranded wire is made of a plurality of strands in contact with the insulating coating layer to form a hollow shape, the heat-softened portion is partially deformed when contacting the strand, and follows the shape of the compression stranded wire. It will be.

  In addition, when heating the compression die to a predetermined temperature, the strand is passed through the inside, so that the strand is heated and the temperature rises to a predetermined value and reaches the predetermined temperature. Since the wire comes into contact with the insulating coating layer, the contact portion of the insulating coating layer is partially deformed and conforms to the shape of the compression stranded wire.

  Furthermore, when each of the strands is heated to a predetermined temperature, the strand that has reached the predetermined temperature contacts the insulating coating layer in the same manner as when the compression die is heated. Part of the contact portion of the layer is deformed to conform to the shape of the compression strand.

  As described above, when the heat treatment is performed, the insulating coating layer has a contact portion with the shield conductor in close contact with and deformed along the inner surface shape of the shield conductor. The adhesion strength between the conductors is increased.

  The said insulation coating conductor can be supplied to the center part of the said compression die | dye, rotating in the same direction as the rotation direction of the said assembly stranding machine.

  According to this configuration, since the supply is performed while being rotated in the same direction as the rotating direction of the collective stranding machine, it is possible to prevent the insulation-coated conductor from being twisted, or to suppress it to such an extent that it does not affect even if it enters. Thus, the center conductor can be stably positioned at the center of the coaxial cable, and the characteristics can be stabilized and improved.

  Further, since the pitch of the compression stranded wire is different from the twist pitch of the insulating coated conductor, in the case of the insulating coating layer provided with the columnar portion, the strand of the compressed stranded wire does not fall between the columnar portions.

  The supply of the insulating coated conductor can be completely synchronized with the rotation of the collective stranding machine.

  According to this configuration, it is possible to prevent any twist from entering the insulating coated conductor. When the central conductor of the insulation-coated conductor is a single wire, waviness is particularly likely to occur, and it is necessary to rotate it completely synchronously.

  According to the coaxial cable and the method of manufacturing the same according to the present invention, the adhesion between the insulating layer and the shield is increased, whereby the pulling strength is improved, and the terminal processability (such as dimensional accuracy) is improved accordingly.

  In addition, there is no residual strain in the insulating coating layer, and the dimensional accuracy during terminal processing and connector mounting is improved.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, preferred embodiments of the present invention will be described in detail based on examples.

  FIG. 1 shows a first embodiment of a coaxial cable 10 according to the present invention. The coaxial cable 10 shown in the figure includes a central conductor 12, an insulating coating layer 14, a shield conductor 16, and a protective coating layer 18.

  The center conductor 12 is comprised from the strand wire (copper wire) of a circular cross section, for example. The stranded wire may be a single copper wire. The insulating coating layer 14 is an electrically insulating layer formed so as to cover the outer periphery of the center conductor 12, and in the case of this embodiment, an annular portion 20 that covers the outer periphery of the center conductor 12, and the annular portion 20. And three columnar portions 22 extending radially in the radially outward direction.

  The insulating coating layer 14 is formed by extruding, for example, a fluorine-based resin such as PTFE, FEP, or PFA, or a synthetic resin such as APO (amorphous polyolefin) resin or PEN (polyethylene naphthalate) on the outer periphery of the center conductor 12. The annular portion 20 and the columnar portion 22 can be integrally formed at the same time.

  In the case of the present embodiment, the insulating coating layer 14 has three columnar portions 22 extending outward from the center, and each columnar portion 22 has a substantially cross-sectional shape that is tapered at the tip side. It is formed in a triangular shape.

  Each columnar portion 22 extends radially at equiangular intervals (120 °) in the cross section, and extends linearly along the longitudinal axis direction of the coaxial cable 10 while maintaining this interval. .

  The shield conductor 16 is provided so as to be in contact with the outer periphery of the columnar portion 22 of the insulating coating layer 14. The shield conductor 16 is partitioned in the circumferential direction by the columnar portion 22 inside the shield conductor 16 and extends in the longitudinal direction of the coaxial cable 10. Three continuous voids 24 are provided.

  In this case, three air gaps 24 are equally arranged in the circumferential direction with the center conductor 12 at the center, and in the cross section, the area ratio is relative to the area of the portion excluding the center conductor 12 and the shield conductor 16. It is desirable to occupy 50% or more.

  In the present embodiment, the shield conductor 16 is formed of a hollow compression stranded wire. Such a compression stranded wire is formed in a hollow shape by arranging a plurality of strands 26 having a circular cross section on the same circumference and passing the compression dies while twisting each strand 26 in one direction. .

  At this time, the strands 26 are plastically deformed and part of the outer circumferences in contact with each other are twisted, so that they form a stable structure (arch structure) in close contact with the stone wall, The shape is maintained without breaking.

  In the case of the present embodiment, the insulating coating layer 14 is a deformed portion 28 that is in contact with the shield conductor 16 along the inner surface shape of the shield conductor 16. Specifically, the deformed portion 28 is formed at the tip of the columnar portion 22 of the insulating coating layer 14, and in this embodiment, the contact portion of each shield conductor 16 with the strands 26 is the strand 26. The surface is deformed along the inner surface, and the surfaces are in close contact with each other.

  As described in detail in the specific examples described later, such a deformed portion 28 heats and softens the insulating coating layer 14 when the insulating coating conductor is disposed and introduced into the central portion of the collective stranding machine, and a compression die. Is heated to a predetermined temperature, and each of the strands 26 is heated to a predetermined temperature.

  The protective coating layer 18 is provided so as to cover the outer periphery of the shield conductor 16, but the protective coating layer 18 is not necessarily provided, but when it is provided, it is the same as the insulating coating layer 16. For example, a fluorine-based resin such as FEP or PFA, or a synthetic resin such as amorphous polyolefin resin or PEN (polyethylene naphthalate) can be formed by extrusion molding on the outer periphery of the shield conductor 16. Note that the outermost diameter of the coaxial cable 10 of the present embodiment can be 1 mm or less.

  According to the coaxial cable 10 configured as described above, the three gap portions 24 that are continuous in the longitudinal direction are provided inside the shield conductor 16, so that the dielectric constant (between the center conductor 12 and the shield conductor 16 ( Equivalent dielectric constant) can be reduced.

  Further, in the coaxial cable 10 of the present embodiment, the shield conductor 16 is composed of a compression stranded wire, and the stranded wire has good shielding characteristics because the strands 26 are in close contact with each other. Although the strands 26 are joined to each other, they are not integrated with each other, and therefore have good flexibility.

  In the case of the present embodiment, the insulating coating layer 14 is a deformed portion 28 that closely contacts the contact portion with the shield conductor 16 along the inner surface shape of the shield conductor 16. The adhesion strength between the shield conductor 16 and the shield conductor 16 increases.

  FIG. 2 shows a coaxial cable according to a second embodiment of the present invention. The same or corresponding parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof is omitted. Only explained.

  Similar to the first embodiment, the coaxial cable 10a shown in the figure includes a central conductor 12a, an insulating coating layer 14a, and a shield conductor 16a. In the case of the present embodiment, the central conductor 12a and the shield conductor 16a are substantially the same as in the first embodiment, and in particular, the shield conductor 16a is a compression twist composed of a plurality of strands 26a as in the first embodiment. Each of the strands 26a is composed of a wire, and a part of the outer periphery that is in contact with each other is plastically deformed, twisted, and in close contact with a stone wall shape to form a stable structure (arch structure) It has become.

  The insulating coating layer 14a is an electrically insulating layer formed so as to cover the outer periphery of the center conductor 12a. For example, the insulating coating layer 14a is a fluorine-based resin such as PTFE, FEP, or PFA, or APO (amorphous polyolefin) resin, PEN ( A synthetic resin such as polyethylene naphthalate is extruded on the outer periphery of the center conductor 12a in an annular shape.

  In the case of the present embodiment, the insulating coating layer 14a is a deformed portion 28a where the contact portion with the shield conductor 16a is in close contact with the inner shape of the shield conductor 16a. Specifically, the deformed portion 28a is formed on the outer peripheral edge of the insulating coating layer 14a. In this embodiment, the contact portion of the shield conductor 16a with each strand 26a is formed on the inner surface of the strand 26a. It is deformed into a concave shape along the surface and the surfaces are in close contact with each other.

  Even in the coaxial cable 10a configured as described above, the shield conductor 16a is formed of a compression stranded wire, and the strand wire 26a is in close contact with each other. Although the wires 26a are joined to each other, they are not integrated with each other, and thus have good flexibility. Further, as in the above embodiment, the adhesion strength between the insulating coating layer 14a and the shield conductor 16a is increased.

  FIG. 3 shows a third embodiment of the coaxial cable according to the present invention. The same or corresponding parts as those in the above embodiment are designated by the same reference numerals and the description thereof is omitted. Only explained.

  Similar to the first embodiment, the coaxial cable 10b shown in the figure includes a central conductor 12b, an insulating coating layer 14b, and a shield conductor 16b. In the case of the present embodiment, the center conductor 12b and the shield conductor 16b are substantially the same as in the first embodiment, and in particular, the shield conductor 16b is a compression twist composed of a plurality of strands 26b as in the first embodiment. Each of the strands 26b is composed of a wire, and a part of the outer periphery that is in contact with each other is plastically deformed, twisted, and in close contact with a stone wall shape to form a stable structure (arch structure) It has become.

  The insulating coating layer 14b is formed by extrusion molding of a synthetic resin as in the first embodiment, and includes an inner annular portion 140b that covers the outer periphery of the center conductor 12b, and a plurality of couplings that extend outward from the inner annular portion 140b. Part 141b and outer annular part 142b for coupling the outer peripheral edge of connecting part 141b, and configured to divide the circumferential direction of gap 24b defined by inner and outer annular parts 140b and 142b by connecting part 142b. doing.

  In the case of the present embodiment, the connecting portion 141b is composed of three pieces, and the three connecting portions 141b extend radially outward from the center at equal angular intervals.

  In the case of the present embodiment, the insulating coating layer 14b is a deformed portion 28b where the contact portion with the shield conductor 16b is in close contact with the inner shape of the shield conductor 16b. Specifically, the deformed portion 28b is formed on the outer peripheral edge of the outer annular portion 142b of the insulating coating layer 14b, and in the case of this embodiment, the contact portion with each strand 26b of the shield conductor 16b It is deformed into a concave shape along the inner surface of the line 26b, and the surfaces are in close contact with each other.

In the third embodiment configured as described above, the same effects as those of the first embodiment can be obtained.
Next, the manufacturing method of the coaxial cable according to the present invention will be described based on specific examples.

Example 1

1 is a specific example when the coaxial cable 10 having the cross-sectional shape shown in FIG. 1 is manufactured. In this manufacturing method, Thus, the insulating coated conductor 30 having the cross-sectional shape shown in FIG. 4 is produced.

  The insulated conductor 30 has a stranded wire formed by twisting seven 0.065 mm silver-plated copper wires as a central conductor 12, which is led to a crosshead die and has a through hole similar in shape to the insulated conductor 30. At an extrusion temperature of 350 ° C. while being drawn at a take-up speed of 11 m / min (tetrafluoroethylene-perfluorovinyl ether copolymer (hereinafter abbreviated as PFA resin)) (AP-201: trade name) , Manufactured by Daikin Industries, Ltd., and a dielectric constant of 2.1) is extrusion-coated to form an insulating coating layer 14. In this case, the size of the virtual circumscribed circle connecting the tips of the columnar portions 22 was 0.485 mm. In this case, it is desirable that the size of the virtual circumscribed circle is set to be slightly larger than the inscribed circle of the shield conductor 16 formed by a compression stranded wire.

  Next, the forming process of the shield conductor 16 by the compression strand was performed using the single twist type collective stranding machine 34 and the rotation supply device 36. FIG. 5 is an explanatory view showing the state of processing at this time.

  The collective stranding machine 34 is provided with a swivel portion 38 provided with a compression die 36 at a leading end of the concentrator, a winding bobbin 40, and a traverse mechanism 42 of the winding bobbin 40, and in front of the compression die 36. An alignment guide plate 44 is provided.

  In the alignment guide plate 44, an insertion hole 44a of the insulating coated conductor 30 is formed in the center, and a plurality of insertion holes 44b of the element wire 26 are formed in the periphery thereof. In addition, a twister 46 is installed in front of the alignment guide plate 44, and the core bobbin 32 around which the insulation-coated conductor 30 is wound is attached to the twister 46.

  When the compression stranded wire is formed on the outer periphery of the insulating coated conductor 30, the insulating coated conductor 30 unwound from the core bobbin 32 is placed at the center of the compression die 36 via the alignment guide plate 44 as shown in FIG. The tip is fixed to the take-up bobbin 40 by being inserted.

  At the same time, the plurality of strands 26 are inserted into the outer periphery of the compression die 36 via the alignment guide plate 44. In this state, the collective stranding machine 34 is driven to turn the turning unit 38 in a predetermined direction.

  At this time, the insulating coated conductor 30 is supplied to the central portion of the alignment guide plate 44 while being rotated by the untwisting machine 46 in the same direction as the turning direction (twisting direction) of the turning portion 38 at a rotation speed of 700 rpm. .

  Further, the insulating coated conductor 30 is inserted into the heating device 50 behind the alignment guide plate 44, heated at a temperature of 250 ° C., and softened by heating. FIG. 6 is a detailed view of the heating device 50 used at this time.

  The heating device 50 shown in the figure is of a hot air type, and has a metal pipe 51 having both ends opened through which the insulating coating conductor 30 is inserted, and a cylindrical heating cylinder covering the outer periphery of one end side of the metal pipe 51. 52 and a hot air generator 54 provided at one end of the heating cylinder 52.

  In the metal pipe 51, approximately half of the entire length protrudes outward from one end of the heating cylinder 52, and the distal end side of the heating cylinder 52 is fixed to the outer peripheral surface of the metal pipe 51. The rear end side of the heating cylinder 52 is a flat surface, and the insertion hole 55 of the insulating coated conductor 30 is formed through the central axis thereof.

  The insertion hole 55 is coaxial with the central axis of the metal pipe 51, and the opening on the rear end side of the metal pipe 51 is disposed in the vicinity of the insertion hole 55. In the heating device 50 configured as described above, when the hot air W is discharged from the hot air generator 54 into the heating cylinder 52, the hot air W enters the inside through the opening on the rear end side of the metal pipe 51, and the metal pipe 51. It is discharged to the outside from the opening on the tip side.

  At this time, since the insulating coated conductor 30 is inserted into the metal pipe 51 through the insertion hole 55, the conductor 30 moves at a predetermined speed together with the hot air W into the metal pipe 51, and the process of this movement. Then, it is heated at a predetermined temperature, for example, a temperature lower than the melting point of the resin for forming the insulating coating layer 14 and above the softening point, for example, a temperature of 250 ° C., and supplied to the compression die 36.

  On the other hand, as the strand 26, 17 silver-plated copper wires having an outer diameter of 0.117 mm are used and arranged in an annular shape on the outer periphery of the alignment guide plate 44. The shield conductor 16 is formed by a compression twisted wire having an outer diameter of 0.70 mm and an inner diameter of 0.480 mm while being twisted at a Pt of 6.2 mm (700 rpm) while being compressed through a compression die 36 having a diameter of 0.701 mm. did. The winding speed of the winding bobbin 40 was 4.4 m / min.

  The compression die 36 is provided with a taper from the entrance to the back side, and the strands 26 inserted into the compression die 36 move closer to each other as they move to the back side. By gradually plastically deforming and closely adhering to each other, by turning the swivel portion 38 in this state, twist is added, and such a form is continuously formed.

  Next, the obtained intermediate is guided to a crosshead die, and PFE resin (AP-201: trade name, manufactured by Daikin Industries, Ltd.) is thickened with a round die having a diameter of 3φ while being drawn at a take-up speed of 11 m / min. A protective coating layer 18 was formed by coating with 0.05 mm to obtain a coaxial cable 10 having a final outer diameter of 0.80 mm shown in FIG.

  As a result of cutting the obtained coaxial cable 10 and observing its end face, there was no protrusion of the insulating layer, the shield was further removed, and the twist pitch of the core (insulating layer 14 + center conductor 12) was examined to be 6.5 mm. It was the same as the set pitch set in the manufacturing stage, and it was found that no residual strain remained.

  In addition, the cable 10 was cut to 10 cm, and the extraction strength of the insulating coating layer 14 with respect to the shield conductor 16 was measured. As a result, it was 506 g. FIG. 6 shows the measurement jig used at this time. The measuring method is to end both ends of a 10 cm cable 10 and fix one end with a gripping part made of a polyethylene plate to create a test sample, sandwiching the gripping plate and the center conductor 12 between both ends of the cable 10 Tensile to the side and the force until they were separated was measured.

  The tensile speed at that time was 5 mm / min. In addition, a pressure trace due to the pressing of the copper wire (element wire 26) was present at the tip of the columnar portion 22 of the insulating coating layer 14. When this cable is processed with a terminal processing machine (manufactured by Schleuniger: Model No. MC252) with a shield layer, an insulation coating layer, and a central conductor, each set to a length of 1 mm and processed with the dimensions as set. Was made.

Example 2

Manufacturing Method of Coaxial Cable 10 of Example 1 Shown in FIG. 1 By the same method as that of Specific Example 1, the insulating coated conductor 30 having a virtual circumscribed circle connecting the tips of the columnar portions 22 having a size of 0.485 mm was formed. . Next, similarly to Example 1, the shield conductor 16 was formed by compression stranded wires using the single twist type collective stranding machine 34 and the rotation supply device 36 shown in FIG.

  At this time, the compression die 36 having a diameter of 0.701 mm was heated to 550 ° C., and the insulating coated conductor 30 was heated by the heating device 50 set at a temperature of 250 ° C. similarly to the specific example 1. At this time, the take-up speed was 4 m / min, and the shield conductor 16 was heat compression molded at a compression rate of 70% to form the shield conductor 16 having an outer diameter of 0.70 mm and an inner diameter of 0.480 mm.

  Next, the intermediate obtained was guided to a crosshead die, and a protective coating layer 18 was formed with a resin thickness of 0.05 mm while taking a PFA resin (AP-201: manufactured by Daikin Industries) while taking it at a take-up speed of 11 m / min. A coaxial cable 10 having a final outer diameter of 0.80 mm was obtained.

  As a result of cutting the cable 10 and observing its end face, no jump out of the insulating layer occurred. The obtained cable 10 was cut into 10 cm and the pulling strength of the insulating layer with respect to the outer conductor was measured. As a result, it was 510 g. Further, when the shield conductor 16 was removed and the twist pitch of the core (insulating coating layer 14 + center conductor 12) was examined, it was found that 6.5 mm was the same as the set pitch set in the manufacturing stage and no residual strain remained. It was. At the tip of the columnar portion 22 of the insulating coating layer 14, there was a compression mark (a mark of melting dent) due to the heated copper wire (element wire 26) being pressed.

  When this cable is processed with a terminal processing machine (manufactured by Schleuniger: Model No. MC252) with a shield layer, an insulation coating layer, and a central conductor, each set to a length of 1 mm and processed with the dimensions as set. Was made.

Example 3

Manufacturing Method of Coaxial Cable 10 of Example 1 Shown in FIG. 1 Insulated coated conductor 30 having a size of a virtual circumscribed circle connecting the tips of columnar portions 22 of 0.485 mm was formed by the same method as in specific example 2. . Next, similarly to Example 1, the shield conductor 16 was formed by compression stranded wires using the single twist type collective stranding machine 34 and the rotation supply device 36 shown in FIG.

  At this time, 17 silver-plated copper wires (element wires 26) were heated to 450 ° C. and supplied to a compression die 36 having a diameter of 0.701 mm. In this case, the heating device 50 was removed. The take-up speed at this time was 4 m / min, and the shield conductor 16 was compression-molded at a compression rate of 70% to form the shield conductor 16 having an outer diameter of 0.70 mm and an inner diameter of 0.480 mm.

  Next, the obtained intermediate was guided to a crosshead die, and a protective coating layer 18 was formed in the same manner as in Example 2 to obtain a coaxial cable 10 having a final outer diameter of 0.80 mm.

  As a result of cutting the cable 10 and observing its end face, no jump out of the insulating layer occurred. The obtained cable 10 was cut into 10 cm, and the extraction strength of the insulating layer with respect to the outer conductor was measured. As a result, it was 540 g. Further, when the shield conductor 16 was removed and the twist pitch of the core (insulating coating layer 14 + center conductor 12) was examined, it was found that 6.5 mm was the same as the set pitch set in the manufacturing stage and no residual strain remained. It was. At the tip of the columnar portion 22 of the insulating coating layer 14, there was a compression mark (a mark of melting dent) due to the heated copper wire (element wire 26) being pressed.

  When this cable is processed with a terminal processing machine (manufactured by Schleuniger: Model No. MC252) with a shield layer, an insulation coating layer, and a central conductor, each set to a length of 1 mm and processed with the dimensions as set. Was made.

Comparative Example 1

  A 7 / 0.065 mm center conductor is guided to a crosshead die, passed through a nozzle having the same shape as in Example 1, and PFA resin (AP--) at an extrusion temperature of 350 ° C. while being drawn at a take-up speed of 11 m / min. 201), an insulation coating conductor 30 as shown in FIG. 4 was obtained. The size of the virtual circumscribed circle passing through the apex of each columnar portion 22 of the insulating coated conductor 30 was 0.470 mm.

  Next, using the apparatus shown in FIG. 5, 17 pieces of 0.117 mm tin-plated copper wires are arranged on the circumference of the insulation-coated conductor 30, and a diameter of 0.701 mm is further applied to the obtained insulation-coated conductor 30. While being drawn on the compression die 36 at a take-up speed of 4 m / min, the shield conductor 16 was compression-molded at a compression rate of 7.0% to obtain a cable intermediate having an outer conductor diameter of 0.70 mm and an outer conductor inner diameter of 0.480 mm.

  Next, the obtained cable intermediate was guided to a crosshead die, and a protective coating was formed with a resin thickness of 0.05 mm while taking a PFA resin (AP-201) while taking it at a take-up speed of 11 m / min. An 80 mm coaxial cable was obtained.

  As a result of cutting the cable and observing its end face, the insulation coating layer protruded 0.5 mm from the shield end face. The obtained cable was cut into 10 cm, and the pulling strength of the insulating coating layer with respect to the shield conductor was measured. As a result, the value was as low as 25 g. Furthermore, when the shield conductor was removed and the twist pitch of the core (insulation coating layer + center conductor) was examined, it was 7.2 mm, which was longer than the set pitch set at the manufacturing stage of 6.5 mm, and residual strain remained. There was found. There was no trace of the copper wire (elementary wire) being pressed at the tip of the columnar portion of the insulating coating layer.

  When this cable was processed with a terminal processing machine (manufactured by Schleuniger: Model No. MC252) with a shield layer, an insulation coating layer, and a central conductor set to a length of 1 mm, the insulation coating layer portion was 1.8 mm. The core was pulled out of the shield, and the dimensions were greatly displaced.

Comparative Example 2

  The outer conductor (shield) was compression-molded under the same conditions as in Example 2 except that the insulation-coated conductor obtained by the same manufacturing method as in Example 2 was not heated by a compression die and heating tank. . In this case, the circumscribed circle passing through the apex of each columnar portion of the insulating coating layer is larger than the inner diameter of the shield conductor (virtual inscribed circle of the compression stranded wire), so that the shape of the compression stranded wire collapses immediately after the twisting process. Occurred and the cable could not be obtained.

  The coaxial cable according to the present invention and the manufacturing method thereof can be obtained without increasing the cost of a coaxial cable excellent in adhesion, and can be effectively used for wiring of a portable terminal.

It is sectional drawing which shows Example 1 of the coaxial cable concerning this invention. It is sectional drawing which shows Example 2 of the coaxial cable concerning this invention. It is sectional drawing which shows Example 3 of the coaxial cable concerning this invention. It is sectional drawing which shows an example of the insulation coating conductor used with the manufacturing method of the coaxial cable concerning this invention. It is explanatory drawing of the single twist type collective stranding machine used with the manufacturing method of the coaxial cable concerning this invention. It is explanatory drawing which shows an example of the heating apparatus used for the collective stranding machine shown in FIG. It is explanatory drawing of the measuring method of the drawing strength of the coaxial cable concerning this invention.

Explanation of symbols

10, 10a, 10b Coaxial cables 12, 12a, 12b Center conductors 14, 14a, 14b Insulating coating layers 16, 16a, 16b Shield conductors 18 Protective coating layers 28 Deformed portions

Claims (10)

In a coaxial cable comprising a central conductor, an insulating coating layer covering the outer periphery of the central conductor, and a shield conductor covering the outer periphery of the insulating coating layer,
The shield conductor is a compression stranded wire in which a plurality of strands are arranged along the outer periphery of the insulating coating layer, and a part of the outer periphery of the strands in contact with each other is plastically deformed to form a hollow shape. Configured,
The coaxial cable according to claim 1, wherein the insulating coating layer closely contacts and deforms a contact portion with the shield conductor along an inner surface shape of the shield conductor.   The coaxial cable according to claim 1, wherein a protective coating layer is provided on an outer periphery of the seal conductor. The insulating coating layer includes an annular portion that annularly covers the center conductor, and one or more columnar portions that extend radially outward from the annular portion,
The coaxial cable according to claim 1, wherein a hollow portion divided by the columnar portion is formed between the compression stranded wires. The insulating coating layer includes an inner annular portion that covers an outer periphery of a central conductor, a plurality of connecting portions that extend outward from the inner annular portion, and an outer annular portion that joins the outer peripheral edges of the connecting portions. Prepared,
The coaxial cable according to claim 1 or 2, wherein a circumferential direction of a gap portion defined by the inner and outer annular portions is divided by the connecting portion.   5. The insulating coating layer according to claim 1, wherein a low dielectric constant resin such as fluorine resin, polyolefin resin, PEN (polyethylene naphthalate) resin, or APO (cyclic polyolefin) resin is used. Coaxial cable.   The coaxial cable according to claim 3, wherein the insulating coating layer has 2 to 4 columnar portions and a hollowness of 50% or more. In the manufacturing method of the coaxial cable composed of the center conductor, the insulating coating layer, and the shield conductor,
A step of obtaining an insulating coated conductor formed by extruding a synthetic resin and forming an insulating coating layer on the outer periphery of the central conductor;
The insulating coated conductor is arranged and introduced into the central portion of a collective stranding machine such as a single twist machine through an alignment guide plate provided in the front,
After arranging a plurality of strands equally on the same circumference along the outer periphery of the insulating coating layer of the insulating coating conductor via the alignment guide plate,
By rotating the compression die while passing the compression die attached to the concentrator of the collective stranding machine, part of the outer circumferences of the strands that contact each other are plastically deformed to form a hollow shape. A step of continuously forming a compression stranded wire on the outside of the insulation-coated conductor to form the shield conductor;
Heating and softening the insulating coating layer, heating the compression die to a predetermined temperature, and heating each of the strands to a predetermined temperature when the insulating coated conductor is arranged and introduced in the central portion of the assembly stranding machine about,
A method for manufacturing a coaxial cable, comprising performing a heat treatment selected from at least one of the following.   8. The method of manufacturing a coaxial cable according to claim 7, wherein a protective coating layer is formed of an electrically insulating synthetic resin on an outer periphery of the compression stranded wire after the step of forming the shield conductor.   The method of manufacturing a coaxial cable according to claim 7 or 8, wherein the insulation-coated conductor is supplied to the central portion of the compression die while being rotated in the same direction as the rotation direction of the collective stranding machine. 10. The method of manufacturing a coaxial cable according to claim 9, wherein the supply of the insulation-coated conductor is completely synchronized with the rotation of the collective stranding machine.

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