Preparation of signal transmission coaxial cable and physic foaming insulation layer and mould

Abstract

Said invention relates to improvement to signal transmission coaxial cable, featuring cable internal conductor outer physics sparkle insulating layer being secondary extruding composed double layer compound sparkle insulation. Due to adopting secondary physics sparkle extrusion laminating, said invention not only solves inside and outside cooling down misproportion problem and resulted fault of once extruded moulding of thick physics sparkle insulation, greatly raising radial and longitudinal sparkle hole uniformity without bunlla hole and cuniculus. For example the leakance RF coaxial cable sparkle degree can be raised to more than 78 per cent, reducing cable dielectric constant and dielectric loss tangent value, reducing cable transmission attenuation, voltage standing wave ratio less than 1.15 with fine product consistency. Said invented insulation physics sparkle forming method and mould is suitable for signal transmission coaxial cable sparkle insulation with greater than 10 mm sparkle insulation thickness.

Description

technical field [0001] The invention relates to the improvement of the coaxial cable for signal transmission, in particular to a coaxial cable with a thicker (eg ≥ 10mm) physically foamed insulating layer, preparation of the physically foamed insulating layer and an insulating extrusion die. Background technique [0002] Coaxial cables for signal transmission, in order to reduce the dielectric constant of the insulation and reduce cable attenuation, usually use physical foam insulation to form a uniform and mutually closed cell insulation structure. In some special applications and to save materials, it is necessary to manufacture coaxial cables with insulation thickness greater than 10mm. However, for thick foam insulation, due to the constraints of the physical foaming process, it is impossible to synchronize the inner and outer cooling of the thickness of the foam insulation layer. Uneven cooling inside and outside the insulation layer will lead to poor uniformity of ins...

AI Technical Summary

Problems solved by technology

However, for thick foam insulation, due to the restriction of the physical foaming process, the inner and outer cooling of the thickness of the foam insulation layer cannot be synchronized.

Uneven cooling inside and outside the insulation layer will lead to poor uniformity of insulation radial and longitudinal cells, and serious "big cells" will appear inside the insulation; secondly, due to the large insulation thickness during the water cooling process, the molten plastic will be affected Due to the influence of buoyancy, the phenomenon of "string holes" will appear in the insulating layer close to the conductor

The uneven cells of the foamed insulating layer and the "big cells" and "serial holes" will not only lead to increased cable attenuation, but also lower voltage standing wave performance. The voltage standing wave ratio is usually between 1.25-1.30, which is difficult to achieve Design requirements below 1.15; and it will also cause poor cable consistency, which will cause interference and noise to the signal, and increase attenuation

In order to reduce the phenomenon of uneven foaming, the method of reducing the degree of foaming is usually used, so that the degree of foaming usually can only reach about 76%. However, the low degree of foaming will lead to large cable attenuation and short signal transmission distance, etc. insufficient

In fact, when preparing a thick insulating layer, the use of a low foaming degree has a limited effect on improving the uniformity of foaming, but it will indeed cause a great impact on the performance of the cable.

[0003] Therefore, due to the constraints of the physical foaming process technology, the above-mentioned shortcomings of the physical foaming thick insulating layer have not been effectively solved so far, which has become a major technical problem in the industry

Images