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Causes of uneven and bulged cable insulation surface (I)

Release time：

2023-02-13

source：

network

Due to the different processing technologies such as extrusion temperature, extrusion speed and cross-linking speed used by silane crosslinked cable material from different manufacturers, the extrusion surface quality of low-voltage cable insulation core is also greatly affected. In the process of producing silane cross-linked polyethylene insulated wire core, the common phenomena and causes are as follows:

1. Raw gum phenomenon

Cross-linked insulation cores sometimes have raw rubber phenomenon in the production process, which also become insulation rigid blocks or hard blocks. The main reasons for this phenomenon are:

(1) The temperature of the machine neck or head is not enough, resulting in local cold glue inside;

(2) Poor local plasticization due to insufficient body temperature or shear force;

(3) When the liner of the filter screen is not in place, it will eventually affect the extrusion pressure of the cross-linked insulating material, and will also produce raw rubber, making the surface of the insulating core appear concave-convex hard lumps.

2. Old glue phenomenon

In the production process of cross-linked insulation core, sometimes there will be old glue, which is also known as pre-crosslinking. It is caused by the high head temperature during the extrusion of cross-linked material or the dead angle of cross-linked material staying in the flow channel for a long time. The old glue is amber. The longer the retention time is, the darker the color is. The higher the temperature is, the darker the color is. Generally, the causes of old glue are:

(1) If the extrusion speed is too fast, the faster the screw speed is, the stronger the shear force of the cross-linked material in the screw barrel is, which will increase the local temperature of the fuselage and lead to the old rubber phenomenon;

(2) The cross-linked insulating materials stay in the barrel for a long time, and some of the insulating materials are cross-linked prematurely, which will cause uneven surface of the wire core when it is out of the mold.

(3) The displacement of the filter screen liner causes the uneven distribution of the rubber pressure at the splitter plate, forming a dead corner of the flow channel. In this case, the old rubber will also be produced. At the same time, it is also possible that the filter screen will lose part of the filtering function. After a long time of production, the old rubber accumulated on the screw head will be carried out during extrusion, and the old rubber particles will be mixed in the insulation layer, resulting in quality problems of the insulation core.

In the next three years, the State Grid will invest 21 billion yuan to make good use of electricity in deeply poor areas (II)

Causes of uneven and bulged cable insulation surface (II)

In the next three years, the State Grid will invest 21 billion yuan to make good use of electricity in deeply poor areas (II)

Causes of uneven and bulged cable insulation surface (II)