1 concept
Bare stranded conductor is the process of twisting several single wires together according to certain directions and rules to form a whole core.
2 features
2.1 Good flexibility
Broadly speaking, the thinner the wire, the more flexible it is. Stranded wire is made up of many thin metal wires and is therefore relatively flexible. However, the flexibility of the stranded wire has a great relationship with the process parameters selected during stranding.
The flexibility of the stranded wire is related to the following factors:
For stranded wires with the same cross-section, the more single wires used, the thinner the single wires and the better the flexibility.
For stranded wires with the same structure, generally the smaller the pitch of the corresponding stranded layer, the softer it is.
To make the wire more flexible, multiple strands can be used.
2.2 High reliability
When single wires are used as cable conductors, the reliability of the individual wires can be reduced by defects and material inhomogeneities in the manufacturing process. With the core of multiple single wires twisted, the defects can be dispersed, and the reliability of the wire is obviously improved.
2.3 Strong
A stranded wire with the same cross-sectional area is much stronger than a single wire.
2.4 Good stability
When the twisted wire is bent, the position of each single wire is in the upper elongation zone and the lower compression zone of the twisted wire in turn. The single wire will not be elongated and compressed, and the position of the single wire will not move, and the structure has good stability.
2.5 Reduce eddy current loss and improve power transmission effect
3 forms of stranded wire
3.1 Regular stranding
It is a twisting method in which single wires or strands are twisted in concentric circles, adjacent layers are twisted in opposite directions, and layers are regularly twisted around the axis of the twisted wire.
3.2 Irregular stranding
Informal stranding methods include bundle stranding, special stranding (fan-shaped, semi-circular, and tile-shaped cores), circular compacted cores, shaped wire stranding, etc.
4 process parameters
4.1 Stranding direction
The direction of texture is divided into right direction and left direction. Generally, the outermost layer of bare stranded wire is right-handed, and the outermost layer of conductive core is left-handed.
Direction judgment: You can use your left or right hand to put your palm upwards, spread your thumbs apart, and keep the other four fingers close together. The four fingers that are close together are along the axis of the twisted wire. If the oblique direction of the right thumb is consistent with the oblique direction of the single wire, it is the right direction (z direction) ), if the slant of the left thumb is consistent with the slant of the single line, it is left (S direction).
4.2 Strand pitch measurement
To measure the pitch of wire harness products, the actual measurement method can be used, that is, take out a section of wire harness products, cut off one of the surface and mark it at the cut point, remove 10 spirals in the opposite direction of the wire harness, and then use a ruler to measure and remove 10 spirals. The length of the helical part of the stranded wire, and then divide the obtained length data by 10 to obtain the pitch length of the bundled wire.
4.3 Pitch ratio
The pitch ratio of the stranded wire refers to the ratio of the pitch length of the stranded wire to the diameter of the stranded wire, that is, the pitch is a multiple of the diameter. The smaller the pitch ratio, the better the flexibility; the smaller the gap between each single wire, that is, the more densely twisted; and the greater the difference between the pitch and the actual length of a single wire at a pitch, the greater the difference between the pitch and the actual length of the single wire, the same length of twisted wires. The length of the single line used is longer.
