Waterproof digital cable design and manufacturing technology
I. Introduction
With the rapid development of communication technology, digital communication cable products have been widely used, and the product structure has also been diversified. Water-blocking digital cable is an important branch of digital cable products. It is mainly used outdoors. It has the function of preventing water vapor and moisture from entering the inside of the cable during wind and rain and wet seasons, so that it can maintain good transmission performance. At present, there are various types of water-blocking digital cables in the integrated wiring market. Since there are no uniform industry standards for water-blocking cables, the products designed by various manufacturers are also varied. This article focuses on the most commonly used types in the industry and combines with our company. The experience of the new water-blocking digital cable provides a brief introduction to the structure, performance, manufacturing process and application prospects of this type of data cable.
Second, the structure characteristics of several commonly used water blocking cables in the industry
2.1 The main types of water-blocking digital cables:
Since the current water-blocking digital cable is not domestic or foreign, there is no corresponding product standard, and each manufacturer is also self-developed according to the actual needs of the customer. Therefore, the design of the water-blocking digital cable is also different. However, most of the water-blocking digital cables on the market today only have short-term moisture-proof functions, and they cannot function in a true sense. Of course, after special design, waterproof digital cables can still be used to block water.
At present, water-blocking digital cables are widely used in the network cabling market. There are basically three structures, namely: water-blocking water-blocking structure; grease-filled water-blocking structure; and water-blocking structure of double-layer sheath structure. The water-blocking cables of these three structures are widely accepted because of their simple structure, easy production and processing, and convenient for users, and are widely used by users.
2.2 Water blocking effect of three commonly used water blocking digital cables:
According to the effect of water blocking, it can be divided into two ways: horizontal water blocking and longitudinal water blocking. The following three types of water-blocking digital cables have different water-blocking effects and production processes. The following is a brief introduction:
Horizontal water blocking method:
(1) Water-blocking water-blocking structure: This form is wrapped around a cable-cable core with a water-blocking strip. Currently, there are various types of water-blocking strips used by various manufacturers. The water-blocking belt standard has the following four types of water-blocking belts as specified in YD/T1115.1-2001: single-sided water-blocking belt – a composite of a single-layer polyester fiber nonwoven fabric and a highly water-absorbing expansion material. Double-sided water-blocking tape - polyester fiber non-woven fabric - high water-absorbent expansion material - polyester fiber non-woven fabric in turn; composite film single-sided water blocking tape - from polyester film - high water absorption expansion material - Polyester fiber non-woven fabrics are sequentially composited; double-coated water-repellent tapes are made of polyester film - polyester fiber nonwoven fabric - high water-absorbent expansion material - polyester fiber nonwoven fabric; All four materials have water blocking properties, but when using digital cables, we recommend using a laminated water blocking tape to ensure the electrical performance of the product.
(2) Double-sheath water-blocking structure: The digital cable of this structure is actually a common type of unshielded digital cable, except that the sheath is made of polyvinyl chloride (PVC) as the inner sheath and polyethylene (PE) as the outer sheath. The double-layered jacket structure only. Since there is no substantial water-blocking element in the entire cable core, its water-blocking function only depends on the double-layer sheath material, which enhances the thickness of the sheath layer. Actually, it has a certain lateral water-blocking effect. Because polyethylene (PE) is used as the outer sheath, it has the functions of preventing ultraviolet rays and anti-aging when it is wired outdoors. Therefore, such products are also popular in the market and occupy a certain market share.
Longitudinal water blocking method:
(3) Ointment filling water blocking structure: This type is the most widely used structure on the market. It is filled with a cold grease or hot grease in the cable core, which is mainly used to fill the air in the cable core. The gap prevents the water vapor from infiltrating from the ends of the cable to achieve the effect of water blocking. Finally, polyethylene (PE) is generally used as the sheath to enhance the water blocking function and the anti-sunlight aging ability. After experimental tests, the cable of this structure has excellent longitudinal water blocking effect, but only has some moisture-proof function in the horizontal direction and does not have water blocking function.
The above-mentioned several types of water-blocking digital cables are used in the market, and each manufacturer is also a comprehensive factor of comprehensive customer demand or manufacturing cost, and according to different customers, cables of different structures are produced. However, we also need to recognize that the above-mentioned products have good lateral water blocking effect or good longitudinal water blocking effect, and there are few products with two-way water blocking.
Third, the design and key control points of the two-way water blocking digital cable
3.1 Overall design of two-way water-blocking digital cable:
Based on the original production of water-blocking digital cable, our company has developed a structure that uses imported hot grease filling and laminating single-sided water-blocking tape longitudinally. This structure has been shown by many experiments to have excellent laterality. A new two-way water-blocking digital cable with water blocking function and excellent longitudinal water blocking function.
Due to the introduction of the water blocking structure, the working capacitance value between the cable pairs is changed. The capacitance variation varies with the structure, so in order to ensure that the water blocking digital cable meets the industry standard YD/T1019-2001, Category 5, Super 5 The electrical performance of the cable, the cable must be redesigned, from insulated single wire extrusion to wire core cable and water blocking tape longitudinal package molding, there are differences.
3.2 Selection of water blocking materials:
(1) Selection of hot ointment materials:
All of us use hot grease, mainly considering the hot grease in the online filling, because of its good fluidity, the entire cable core can be filled more fully, so that the capacitance of the entire cable is more uniform, so the electrical parameters such as impedance and return loss are more stable. . However, cold grease filling is not the case, because of its poor fluidity, the relative viscosity is large, so the line filling is not uniform, it is easy to appear some places filled with supersaturation, and some places basically have no grease. Of course, the quality of the ointment has a great influence on the propagation speed and propagation delay of the finished cable. Therefore, we recommend the use of imported ointment.
The following table is the main technical indicators of hot ointment:
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