JP2012124172A - Molding die used for manufacturing hollow core body for coaxial cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a hollow core body with high hollowness and sufficient circularity.SOLUTION: A molding die 20 has a flange 22 and a tip projection part 24. A center hole 24a for inserting an inner conductor 12 is provided on the projection part 24. An inner annular hole 24b is provided adjacent to an outer periphery of the center hole 24a, and six linear holes 24c radially extending outward at equal angle intervals are provided from the outer periphery of the inner annular hole 24b. An outer annular hole 24d coupling the linear holes 24c are provided between outer ends of the linear holes 24c. Using such a die 24, while the inner conductor 12 is inserted in the center hole 24a, resin molten from the inner and outer annular holes 24b, 24d and the linear holes 24c is extruded almost vertically downward, and the molten resin is cooled and solidified, so as to obtain a hollow core body with a predetermined cross section shape.

Description

  The present invention relates to a forming die used for manufacturing a hollow core body for a coaxial cable.

  With the progress of IT, high performance (low loss, high speed transmission), lightness and thinness (cable size reduction) are also required for coaxial cables, and therefore the dielectric constant of insulators and the improvement of their stability are required. It has been. The reduction of the dielectric constant of the insulator can be achieved by using an aero core (rib structure hollow core), but has the following drawbacks.

(1) Since the rib is an open structure, when a coaxial cable is provided with a horizontal winding shield and a braided wire shield, when the connector is attached by soldering, the solder enters the hollow part and the characteristic impedance changes. was there.

(2) When applied to a coaxial cable having a structure in which a plurality of cores of aero cores (straight rib structure) are arranged, the ribs mesh with each other and cannot be cabled well.

(3) With the aero core (both straight rib and spiral rib structure), the rib body is an open structure, so when a horizontal winding shield or braided wire shield is applied, the outer shape of the shield becomes a polygon, and the specified performance is obtained. In some cases, the outer shape was not stable.

(4) After shielding the braided wire, there is a case where tin is impregnated (semi-flexible coaxial cable) in order to enhance the shielding effect. However, tin may enter the hollow portion and a predetermined characteristic may not be obtained.

Such a drawback can be solved by making the cross section having a perfect circular outer shape and a plurality of hollow chambers inside the lotus structure insulator. A method of manufacturing such a lotus structure (insulator-covered) core body is proposed in Patent Document 1. However, the manufacturing method of the core body disclosed in Patent Document 1 has a technical problem described below particularly in the structure of the forming die.
JP 2003-249129 A

  Patent Document 1 proposes, as a manufacturing method, a method of performing insulation coating using divided porous dies, and a method of performing a first coating with a rib structure and then performing a two-stage coating in an annular shape. However, each of these manufacturing methods has problems described below.

  In the former manufacturing method, since the divided parts are bonded, it is necessary to make the divided holes adjacent to each other. For this reason, the draft rate cannot be increased, shape stability is poor, and there is a possibility that the divided parts may be broken. In addition, there is a problem that the outer shape is difficult to be a perfect circle due to a mutual shift or the like.

  In the latter manufacturing method, a plurality of dies are required, the process becomes complicated, and the annular coating and the rib structure (cross portion) are bonded to each other, so that a force to tighten the annular coating itself is required, and the thickness of the annular coating is reduced. If it is thin, it becomes a polygonal shape, and in order to ensure roundness, it is necessary to increase the thickness. However, if it is increased, there is a problem that the hollowness is reduced.

  The present invention has been made in view of such a conventional problem, and provides a forming die used for manufacturing a hollow core body for a coaxial cable that has a high hollow ratio and can ensure roundness. For the purpose.

In order to achieve the above object, the present invention provides a molding die for use in manufacturing a coaxial cable core body having an inner conductor and an insulating coating layer provided on the outer periphery of the inner conductor. An inner annular portion that covers the inner conductor by extruding molten resin while inserting the conductor, a plurality of rib portions that extend radially from the inner annular portion, and an outer annular portion that connects the outer ends of the rib portions A molding die for forming the insulating coating layer including a plurality of hollow portions surrounded by the inner and outer annular portions and the rib portions, wherein the molding die is the hollow of the extruded core body. It has a through hole for introducing internal pressure adjusting air into the part.

  The internal pressure adjusting air can be introduced into the through hole in a pressurized state.

The insulating coating layer is integrally formed of a resin selected from fluororesin, polyolefin, cyclic polyolefin (APO), SPS (syndiotactic PS), polymethylpentene, and polyethylene naphthalate (PEN). Can do.

  According to the molding die used for the production of the coaxial cable hollow core body according to the present invention, a hollow core body having a hollow ratio of 40% or more and a circularity of the outer annular portion of 96.0% or more In particular, the molding die has a through-hole for introducing air for adjusting internal pressure into the hollow portion. By introducing air, the shape stability of the hollow portion and the outer ring shape can be obtained. The roundness of the portion can be ensured satisfactorily, and further, a cooling effect by introducing air is expected.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a hollow core body for a coaxial cable obtained by a forming die according to the present invention. The hollow core body 10 for a coaxial cable shown in the figure includes an inner conductor 12 and an insulating coating layer 14.

The inner conductor 12 is made of copper or a copper alloy fine wire excellent in strength and conductivity, or a single wire plated with a highly conductive metal by these, but may be a stranded wire.

The insulating coating layer 14 is made of a thermoplastic resin, and has an inner annular portion 14a that covers the outer periphery of the inner conductor 12, and six ribs that extend radially outward from the outer periphery of the inner annular portion 14a. A portion 14b and an outer annular portion 14c that connects the outer ends of the rib portions 14b are provided.

In the case of this example, by arranging six rib portions 14b at equal angular intervals along the circumferential direction, the inner and outer annular portions 14a and 14c and the rib portion 14b surround the outer periphery, and Six hollow portions 16 that are continuous in the longitudinal direction are evenly arranged in the circumferential direction with the inner conductor 12 as the center, and the hollow portions 16 are partitioned into small spaces by the rib portions 14b.

The number of the hollow portions 16 is not limited to six, and may be five or more so that the outer end portion does not reach the outer peripheral edge of the insulating coating layer 14, that is, the outer edge of the outer annular portion 14c. Form.

The hollow core body 10 having the above configuration is used as a coaxial cable by providing an outer conductor layer and, if necessary, a protective layer on the outer periphery of the outer annular portion 14c of the insulating coating layer 14. In this case, the outer conductor layer can be formed by metal plating.

In this case, as the activation treatment of the insulating coating layer 14, after wet etching, hydrophilization treatment with fluoroetch (naphthalene / sodium complex), sensitizing with a hydrochloric acid solution of stannous chloride, Further, after activation with a hydrochloric acid solution of palladium chloride, electroless plating is performed.

In addition, when using as a coaxial cable, it can respond to both the case where the single hollow core body 10 is used, and the case where the multiple hollow core bodies 10 are used.

In this example, the outer diameter of the outer annular portion 14c of the insulating coating layer 14 is 5.0 mm or less, the number of the rib portions 14b is three or more, and the proportion of the hollow portions 16 is 40% or more. The roundness of the annular portion 14c is 96.0% or more.

In general, a core for a coaxial cable having high flexibility with an insulation outer diameter of about 5 mm or less uses a foam type insulating layer. If the coaxial cable has a relatively small diameter, the degree of foaming cannot be made extremely large. Therefore, if a hollow ratio of 40% or more is secured, the dielectric constant can be reduced as compared with the foam type coaxial cable.

The hollow insulation structure of this example can secure a hollow ratio of 40% or more, but the number of ribs is 3 or more in order to ensure the roundness of the structure, mechanical characteristics (side pressure, bending characteristics and cable end processing), etc. Is desirable. The number of ribs is preferably not more than 10 in order to ensure a hollow ratio of 40% or more and from the viewpoint of machining accuracy of the die tip.

Here, the porosity, which is the ratio of the hollow portions 16, is the ratio of the hollow portions 16 to the entire insulating portion in the cross-sectional area of the hollow core body 10, and in the present embodiment, six hollow portions. The sum of the cross-sectional areas of 16 is set to be 40% or more of the insulating part (total cross-sectional area of the insulating coating layer 14 + total cross-sectional area of the hollow part 16).

The roundness is the size of the outer diameter of the outer annular portion 14c, where the longest diameter is a, the shortest diameter is b, and the average outer diameter is c (c = (a + b) / 2).
Roundness (%) = (1− (a−b) / c) × 100
It is a value obtained by, and is an index showing how close it is to a perfect circle.

Furthermore, the eccentricity measured in the specific example described later is the eccentricity when the distance between the center point of the outer diameter of the outer annular portion 14c and the center point of the inner conductor 12 is a, and the radius of the outer diameter is b. Rate (%) = (a / b) × 100
And is an index representing the concentric state of the inner conductor 12 and the outer annular portion 14c.

Also, the area withdrawal magnification is
(Outer diameter of die) ² / (Diameter of outer annular portion of hollow core body) ² ... Formula 1
The preferred range is 4 to 300 times, more preferably 4 to 150 times. Exceeding this range is not preferable in terms of production stability.

1 can be extruded as it is in the cross-sectional shape shown in FIG. 1, or the inner conductor 12 is formed of the inner annular conductors 14a and 14c and the rib portions 14b. It is also possible to form the periphery so as to rotate at a constant pitch.

The insulating coating layer 14 may be integrally formed of a resin selected from a fluororesin, polyolefin, cyclic polyolefin (APO), SPS (syndiotactic PS), polymethylpentene, and polyethylene naphthalate (PEN). it can.

The hollow core body 10 having the above-described configuration can be manufactured by using a die 20 shown in FIGS. The dice 20 shown in these figures have a substantially convex cross section, and are provided with a disk-like flange 22 and a tip convex portion 24.

FIG. 3 is an enlarged view of the tip convex portion 24, and FIG. 4 is a plan view of the tip side of FIG. The leading convex portion 24 shown in these drawings is provided with a central hole 24a for insertion of the internal conductor 12 by inserting and fitting a pipe 26 to the shaft core.

An inner annular hole 24b is provided adjacent to the outer periphery of the center hole 24a, and six linear holes 24c extending radially outward from the outer periphery of the inner annular hole 24b at an angular interval are provided. ing.

Further, between the outer ends of the six linear holes 24c, an outer annular hole 24d for connecting them is provided. Using such a die 20, while the inner conductor 12 is inserted into the center hole 24a, the molten resin is extruded substantially vertically downward from the inner, outer annular holes 24b, 24d and the linear hole 24c to cool the molten resin. When solidified, the hollow core body 10 having the cross-sectional shape shown in FIG. 1 is obtained.

In this case, the inner annular portion 14a covering the inner conductor 12 is extruded from the inner annular hole 24b and formed of resin, and the six rib portions 14b extending radially from the inner annular portion 14a are extruded from the linear holes 24c. An outer annular portion 14c formed of resin and connecting the outer ends of the rib portions 14b is extruded from the outer annular hole 24d and formed of resin.

In such a manufacturing method, in the case of the present embodiment, air for adjusting internal pressure is introduced into the plurality of hollow portions 16 surrounded by the inner and outer annular portions 14a, 14c and the rib portions 14b, and is cooled. Then, the area is withdrawn and the area withdrawing magnification is 4 to 300 times. This internal pressure adjusting air is introduced through the through hole 24e of the die 24 shown in FIGS.

In the case of the present embodiment, one through hole 24e is disposed in each of the portions surrounded by the inner and outer annular holes 24b, 24d and the linear hole 24c, and the inner conductor 12 is inserted into the center hole 24a. Then, when this is taken out at a predetermined speed, the external air is accompanied by the air flow from the rear end side (corresponding to the left end in FIG. 2) forward of the through hole 24e. It introduce | transduces in 16 and the internal pressure of each hollow part 16 will be equalize | homogenized.

Such an internal pressure adjusting air is not only introduced into the hollow portion 16 by an air flow that naturally occurs as the internal conductor 12 is pulled, but the internal pressure adjusting air that has been pressurized to a predetermined pressure is hollow. It is also possible to actively inject into the part 16.

5 and 6 show two examples of coaxial cables using the hollow core body 10 shown in FIG. FIG. 5 is an example in which an outer conductor layer 30 made of a braided wire shield is provided on the outer periphery of the outer annular portion 14 c of one hollow core body 10. In this example, a protective coating layer is provided on the outer periphery of the outer conductor layer 30. 32 is coated. The braided wire shield is formed by arranging a plurality of metal single wires in parallel so as to contact each other and braiding them in a mesh shape.

FIG. 6 is an example in which an outer conductor layer 30a made of a horizontal winding shield is provided on the outer periphery of the outer annular portion 14c of one hollow core body 10, and also in this example, the outer conductor layer 30a has a protective coating on the outer periphery. Layer 32 is coated. The horizontal winding shield is formed by arranging a plurality of single metal wires in parallel so as to be in contact with each other, and spirally wound in this state in close contact with the outer periphery of the outer annular portion 14c.

In the example shown in FIGS. 5 and 6, the protective coating layer 32 is provided, but the protective coating layer 32 is not necessarily required. Further, the hollow core body 10 is not limited to a single one, for example, a configuration in which two are arranged in parallel, or three or more are arranged in a straight line so that the outer circumferences are in close contact with each other, and an outer conductor is arranged on the outer circumference. Layers 30 and 30a may be provided.

In addition to providing the outer conductor layers 30 and 30a so as to be in direct contact with the outer peripheral surface of the outer annular portion 14c, for example, tape winding (horizontal winding or horizontal winding made of a synthetic resin film having a metal layer on both sides or one side). The outer conductor layers 30 and 30a can be provided on the upper surface of the outer conductor layers 30a and 30a.

Further, the outer conductor layers 30 and 30a can be impregnated with tin. In this case, in the foam type core, since the bubbles are closed cells, when they are impregnated with tin, they expand due to heat and bite into the braided wire, resulting in insufficient impregnation. However, such a problem does not occur because the hollow core body of this example is open-celled.

Hereinafter, more specific specific examples of the production of the hollow core will be described, but the present invention is not limited to the following specific examples.

Specific Example 1 ( Example of obtaining a round shape by setting the water cooling point with air-cooling + water-cooling swinging method)
As an internal conductor 12, a 0.51 mm annealed copper wire is guided to a crosshead die, and the die 20 at the mouth portion shown in FIG. The ratio 2.1) was coated on an outer diameter of φ1.4 mm, and was gradually cooled by air cooling at an atmospheric temperature of about 30 ° C.

As a result of measuring the point with the largest roundness with an oscillating outer diameter measuring instrument, it was 50 mm from the die surface. The roundness in this case was 96%, and water cooling was performed at this point. By the above method, a hollow core body having an area withdrawal ratio of 35 times was obtained. The coating temperature immediately before cooling with water was 315 ° C., which was higher than the melting point.

When the obtained hollow core body 10 was cut and its dimensions were measured, the thickness of the outer annular portion was 0.07 mm, the thickness of the rib portion was 0.06 mm, and the thickness of the inner annular portion was 0.06 mm. From these values, a hollow core 16 having a hollowness of 58%, a roundness of 96.2%, and an eccentricity of 3% could be obtained.

FIG. 7 is a diagram illustrating an arrangement state of the manufacturing apparatus in the first specific example. In the figure, reference numeral 20 denotes a forming die, and this die 20 has substantially the same structure as that shown in FIG. 2, and the inner conductor 12 is connected to the die 20 via a turn sheave 40. be introduced. An air cooling tube 42 for slow cooling is disposed on the downstream side of the die 20, and a hot air generator 44 with a blower is attached to the air cooling tube 42.

A water cooling tank 46 is installed on the downstream side of the air-cooled cylinder 42, and a water receiving tank 47 is provided below the water cooling tank 46. Between the air cooling cylinder 42 and the water cooling tank 46, there is a non-contact thermometer 48 that measures the temperature of the hollow core body 10 that is led out from the die 20 and gradually cooled by passing through the air cooling cylinder 42. Has been placed.

The above-described die 20, wind-cooled cylinder 42, non-contact thermometer 48, and water cooling tank 46 are arranged in this order in the vertical direction, can be moved up and down on a rail 52 fixed to the gantry 50, and can be arbitrarily It is supported so that it can be fixed in position.

On the other hand, the hollow core body cooled in the water cooling tank 46 is redirected by a sheave 54 provided in the water receiving water tank 47, guided to the Nelson roller 56, and then sent to a winder (not shown). . Immediately after that, the outer diameter of the hollow core body led out from the Nelson roller 56 is measured by the swinging outer diameter measuring device 58.

The oscillating outer diameter measuring device 58 can measure the outer diameter of the hollow core body 10 continuously or intermittently, and measures the measuring device itself while reciprocatingly rotating at 180 ° C. The outer diameter can be measured in the entire circumferential direction of the hollow core body. In the first specific example, the water cooling tank 46 is moved in the vertical direction with respect to the die 20 to measure the outer diameter with respect to the distance between the two. When the distance is 50 mm from the die surface, the roundness is the largest. It was. Therefore, the test production was finished, and the production after that was performed with the distance fixed at this interval.

Example 2
As the inner conductor 12, a φ0.51mm annealed copper wire is led to a crosshead die and passed through the mouth die 20 shown in FIG. 2.1) was coated on an outer diameter of φ1.4 mm and annealed by air cooling at an atmospheric temperature of about 30 ° C. to obtain a hollow core body with an area withdrawal ratio of 35 times.

When the obtained hollow core body was cut and measured for dimensions, the thickness of the outer annular portion was 0.07 mm, the thickness of the rib portion was 0.06 mm, and the thickness of the inner annular portion was 0.06 mm. A core close to a perfect circle shape having a hollow ratio of 58%, a roundness of 96.5%, and an eccentricity ratio of 3% obtained from these values was obtained.

Example 3
As an inner conductor 12, a φ0.51mm annealed copper wire is led to a crosshead die, and the die at the mouth shown in FIG. .1) was coated to an outer diameter of φ1.4 mm, and after coating, it was gradually cooled by air cooling at about 30 ° C. at ambient temperature to obtain a hollow core body. At the time of this coating, air was pressurized into the through hole 24e of the die 20 and supplied at a flow rate of 8 cm ^{3 /} min.

In such a positive air supply, when natural intake alone is used, a pressure drop occurs inside the coating and the outer annular part is pushed inward, or the outer annular part is recessed inward due to insufficient cooling. It is effective for.

The hollow core body obtained at an area withdrawal magnification of 35 times was cut and measured for dimensions. As a result, the outer annular portion had a thickness of 0.07 mm, the rib portion had a thickness of 0.05 mm, and the inner annular portion had a thickness of 0.05 mm. Met. From these values, the hollowness of the hollow portion was 64%, the roundness was 96.5%, and the eccentricity was 3%. Although the thickness of the corner portion tended to decrease due to the air injection, a perfect circle shape could be obtained.

According to the forming die used for manufacturing the coaxial cable core body according to the present invention, since the dielectric constant of the coaxial cable can be reduced, it can be effectively used for downsizing of IT equipment using the coaxial cable. .

It is sectional drawing which shows an example of the core body obtained with the shaping | molding die | dye of the core body for coaxial cables which concerns on this invention. It is explanatory drawing which shows an example of the die | dye used for manufacture of the core body for coaxial cables which concerns on this invention. It is the A section enlarged view of FIG. It is the top view seen from the front end side of FIG. It is sectional drawing which shows an example of the coaxial cable using the core body shown in FIG. It is sectional drawing which shows the other example of the coaxial cable using the core body shown in FIG. It is arrangement | positioning explanatory drawing of the manufacturing apparatus using the shaping | molding die concerning this invention.

DESCRIPTION OF SYMBOLS 10 Coaxial cable hollow core body 12 Center conductor 14 Insulation coating layer 14a Inner ring part 14b Rib part 14c Outer ring part 16 Hollow part 20 Dice 42 Wind-cooled cylinder 44 Water cooling tank

Claims (2)

In a forming die used when manufacturing a core body for a coaxial cable having an inner conductor and an insulating coating layer provided on the outer periphery of the inner conductor,
The molten resin is extruded while the inner conductor is inserted through the center, and the inner annular portion covering the inner conductor, a plurality of rib portions extending radially from the inner annular portion, and the outer ends of the rib portions are connected. A forming die for forming the insulating coating layer comprising an outer annular portion and a plurality of hollow portions surrounded by the inner and outer annular portions and the rib portion,
The forming die for use in manufacturing a hollow core body for a coaxial cable, characterized in that the forming die has a through hole for introducing air for adjusting internal pressure into the hollow portion of the extruded core body.   The forming die for use in the method for producing a hollow core body for a coaxial cable according to claim 1, wherein the internal pressure adjusting air is introduced into the through-hole in a pressurized state.

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