STEEL WIRE ROPE STRUCTURE
Steel wire rope is a machine that consists of a number of moving parts that are designed and manufactured to be in constant interaction with each other. Steel ropes consist of wires, strands and a core. The main element is steel wire. Wire ropes are produced by careful processing and shaping of wires with predetermined physical properties and nominal strength.
Steel ropes are named according to the structures. Special ropes may have their own names (6×19 Seale, 6×36 Warrington Seale, X 53, HD 8 K etc.) extensions like Standard, Filler, Seale, Warrington Seale refers to the thinness, thickness and arrangement of the wires in a strand
Steel ropes are named according to the structures. Special ropes may have their own names (6×19 Seale, 6×36 Warrington Seale, X 53, HD 8 K etc.) extensions like Standard, Filler, Seale, Warrington Seale refers to the thinness, thickness and arrangement of the wires in a strand
Steel ropes are normally made of bright wires that have not been coated. They are galvanized if protection is required due to rust, moisture and steam.
Nominal strength
It refers to the amount of load at which the mm2 of the wires are broken. Some nominal strengths are as follows;
1770 N/mm2 = 180 kgf/mm2
1960 N/mm2 = 200 kgf/mm2
2160 N/mm2 = 220 kgf/mm2
Steel Wire Ropes Direction of lay
During the production of rope, while the wires and the strands are helically shaped, the selected directions of lay indicates the direction of the rope if lay of the strands and the wires in the strand have the opposite direction, then it is called ordinary lay, if have the same direction, then called lang lay. The lay of the strand determines the lay of the rope. The basic lays are seen to figure
Steel Wire Rope Preforming
Preformed means that the wires and strands have been pre – set during manufacture into the permanent helical form they take in the completed rope.
Steel Wire Rope core
There are basically two types of core. There are basically two types of essence. These are called fiber core and steel core. Fiber cores are usually formed from fibers of synthetic products such as sisal and polypropylene. The steel core is again made of steel wires and there are two main types strand core and independent rope core.
Cutting of Steel Wire Rope
Hand cutting tools up to 8 mm rope diameter can be used. But it is necessary to use mechanical or hydraulic cutters for diameters greater than 8 mm. The best method is cutting with grinding disc. If the rope is not scraped, it is not recommended to cut using flaming cutting tools.
The ropes should be cut with grinding dics by seizing with wire as in the figure 4. Wire should be seized to the right and left with 3 times the wire diameter. This process is important in order not to disturb the physical property of the rope
Steel Wire Rope Lubrication
Lubricant applied to steel ropes during production; is used to prevent problems such as corrosion, dust and abrasion due to friction. Lubricants are generally asphalt based.
Steel Wire Rope Abrasion Flexibility Relationship
There are two main features that influence the selection of rope; these are abrasion resistance caused by friction and fatigue resistance due to bending and twisting.
Determination of Equivalent Steel Wire Rope
If you cannot supply the current rope you have used or if you need to use an equivalent rope for any reason,you must check the following rope characteristics
- The diameter of the rope should always be the same.
- The minimum breaking load of the equivalent rope must be equal to or greater than the minimum breaking load of the previous rope.
- Always replace with a rope with the same characteristic. For example, a non-rotating rope should be replaced with a non-rotating rope.
Measuring Steel Wire Rope Diameter
Rope diameters are determined by measuring the circle that just touches the extreme outer limits of the strands. In the measurement of the rope, it is necessary for the caliper’s jaws to contact the two outerstrands (Figure), generally two measurements perpendicular to each other, at least 1 meter apart from two points in the distance. And the average of these four measurement is to be within tolerances. In case of dispute in standarts, it is also foreseen to measure the rope diameter under a certain tension.
Steel Wire Rope Groove and Rope Relation
The diameter of the pulley and drum and the diameter and other characteristics of the grooves on them have a great impact on the rope life. The groove gauges can be used for the diameter and width measurements of the grooves. Drum and pulley made of suitable material are useful for rope life. If the grooves are wider and the rope contact angle is higher, then the rope is ovalized. If grooves are narrower or less than necessary, the wire and strands will get stuck both cases there are inconvenient for the service life of the rope. Generally the rope and groove contact angle should be between 135 – 150 degrees (Figure ).
a. New Rope- New Groove
b. New Halat- Worn Groove
c. Worn Rope- Worn Groove
Unwinding of Steel Wire Ropes
The ropes must be delivered in coils or on reels, when using the rope for the purpose of use or taking into system, the precautions shown in Figure 8 must be complied. Waves occured during the unwinding, cause permanent and undesired damages like kinks and birdcages that lead the rope to be unusable for further applications (Figure 7). It is not possible to repair the ropes that have the damages of kink or birdcage leading the discard of the ropes.
It cannot be the manufacturer’s fault in the rope damage caused by such use errors. In order to avoid similar situations, winding machines should be used in the rope unwinding and cutting operations for certain lengths ropes should be rewind under a preload.
Ropes, are part of a working system, should be very carefully handled and stored before use. In all these activities, rope contact with external influences should be avoided. It should not be forgotten that the ropes are composed of a number of thin wires, as will be seen when they are examined closely, and this situation is very sensitive to external influences.
When the ropes are unwinded from the reels or coils during installation, service and rewinding to the reels, that care should be taken not to cause any damage to the rope and create stress on the ropes due to external factors. No matter what the method is unwinding, the sand, gravel and other hard objects should not be adhered to the rope. Otherwise, it can damage the system and rope when the rope passes through the pulleys during the use due to these hard objects.
It has been tested that it is not a practical and efficient method, even if the problem is not seen in the rope unwinding process by rounding the wooden reel on the ground face.
