Wire rope twist direction and wire rope core code

According to different twisting methods, steel wire rope can be divided into left same direction twisting, right same direction twisting, left alternating twisting and right alternating twisting. The twisting direction of steel wire rope (or strand) refers to the direction of spiral line twisted by strand in rope (or wire in strand). Judgment method: place the rope (or strand) vertically and observe it. If the spiral rising direction of the strand (wire) is from left to top, it is left twist. According to the twisting direction, two letters (Z or s) are used to represent the twisting direction of the steel wire rope, the second letter represents the twisting direction of the strand, "Z" represents the right twisting direction, and "s" represents the left twisting direction. According to the twisting direction of strand and rope, the steel wire rope is divided into:

A right alternating twist ZS: right twist of rope, left twist of strand, the direction of strand twist is opposite to the direction of steel wire twist in strand, which is called alternating twist

B left alternating twist SZ: rope left twist, strand right twist

C right same direction twist ZZ: rope right twist, strand right twist

D left same direction twist: rope left twist, strand left twist

E right mixed twist: right twist of rope, left twist of some strands and right twist of some strands

F left mixed twist: rope left twist, part strand right twist, part strand left twist

The steel wire rope twisted in the same direction has flat and soft surface, bending fatigue resistance and durability; Its disadvantage is that the rope strand is easy to be loose at the broken end of the rope head, and it is easy to rotate and curl and kink when hanging heavy objects. Therefore, it is not suitable to be used alone in hoisting. Interactive lay steel wire rope is commonly used in hoisting operation.

Steel wire rope core and code

A fiber core (natural or synthetic): FC

B natural fiber core: NF

C synthetic fiber core: SF

D. wire rope core: IWR (or iwrc)

E. wire strand core: IWS

The surface state of the steel wire is marked with the following codes:

a. Smooth steel wire: Nat;

b. Grade a galvanized steel wire: zaa;

c. Grade AB galvanized steel wire: Zab;

d. Grade B galvanized steel wire: ZBB

The cross section of the steel wire in the steel wire rope is marked with the following code:

a. Round steel wire: no code;

b. Triangular steel wire: V;

c. Rectangular or flat steel wire: R;

d. Trapezoidal steel wire: T;

e. Oval steel wire: Q;

F. Matching of semi sealing steel wire (or rail shaped steel wire) and circular steel wire: H;

g. Z-shaped steel wire: Z

The cross section of the steel wire rope is marked with the following code:

a. Circular steel wire rope: no code;

b. Braided steel wire rope: y;

c. Flat wire rope

The twisting spiral direction (i.e. twist direction) of the steel wire in the rope strand and the strand in the rope and the mutual coordination between the twist direction of the wire in the strand and the twist direction of the strand in the rope (twist method). Twist direction is divided into left twist and right twist; There are two kinds of twisting methods: alternating twisting and same direction twisting. According to the mutual cooperation of twist direction and twist method, the wire rope twist method is divided into four types: right alternating twist, left alternating twist, right same direction twist and left same direction twist, as shown in Figure 1. Place the steel wire rope (rope strand) vertically and observe the twisting spiral direction of the rope strand (steel wire). The upward and rightward twisting direction starting from the left side of the center line is called right twisting, which can be expressed in accordance with "Z"; The upward and leftward twist direction starting from the right side of the centerline is called left twist, which can be represented by "s". Cross twisting refers to the twisting direction of the strand opposite to that of the rope, also known as reverse twisting. The same twist refers to the same twist direction of the strand and the rope, which is also called forward twist. Right alternating twist means that the steel wire rope is right twisted and the rope strand is left twisted. Left alternating twist means that the steel wire rope is left twisted and the rope strand is right twisted. Right common twist means that the twist direction of steel wire rope and rope strand is right twist. Left same twist means that the twist direction of rope and strand is left twist.

From the appearance, the position of the outer steel wire is almost parallel to the longitudinal axis of the steel wire rope. Therefore, the characteristics of the cross twisted steel wire rope in use are: (1) the contact length between the surface steel wire and its drum or pulley surface is short, that is, the support surface is small and the wear is fast (Fig. 2), and in use, the steel wire in the rope is not easy to separate from both sides when it is squeezed, which is easy to produce uneven wear and explosive fracture of the steel wire; (2) Due to different twist directions, the internal steel wire arrangement of the steel wire rope is different, which will lead to the difference of its performance, and the twist deformation is large, the flexibility is poor, and the bending stress of the steel wire is large when in use; (3) Because the residual stress in the rope and strand or the rotating torque caused by load can offset each other after interactive twisting, it is not easy to cause the loosening of the steel wire rope and the rotation during use; (4) In the alternating twist steel wire rope, the inclination of the center line of the steel wire and the rope is only between 0o and 5O, the surface appearance is flat, the use is stable and the vibration is small.

From the appearance of the co twisted steel wire rope, the position of the outer steel wire is inclined to the longitudinal axis of the steel wire rope, and the inclination angle is about 30o. The characteristics of the same direction twisted wire rope are: (1) when in use, the contact area between the surface steel wire and the surface of the winding Jane or pulley is long, that is, the support surface is large, so the wear resistance is good; (2) Good flexibility and good bending fatigue resistance; (3) Due to the same twist direction, the total bending and torsion deformation of the steel wire after being twisted into the rope is small, and the stress of the steel wire in the rope is relatively uniform during use, which is also beneficial to improving the fatigue life of the steel wire rope; (4) The rotation is slightly larger, which is prone to loose twist and kink. It is generally suitable for use when both ends are fixed.

Among the varieties of steel wire rope, the right alternating twist is the most. Generally, when the supplier and the demander determine the twist direction, if the flexibility is emphasized, the same direction twist can be selected, and if the non looseness and non rotation are emphasized, the interactive twist can be selected. Whether to choose left twist or right twist depends on factors such as equipment conditions and operation habits.