Selection And Maintenance of Rotary Drilling Rig Wire Rope

Rotary drilling rigs use the average service life of each domestic wire rope for the construction of 800 ~ 1000m, up to 3500m, the shortest only 15m.

Reasonable priority wire rope, first of all must understand the rotary drilling rigs use wire rope types and characteristics. To determine the type and diameter of the wire rope for the rated lifting capacity of different models to ensure the safety of the equipment in the construction process.

Selection of wire rope type

One end of the wire rope used in the rotary drilling rig is fixed on the reel of the winch with a wedge, and the other end is fixed on the lifting guide at the upper end of the drill pipe. In the process of rotary drilling with the drill pipe driven by the power head, the lower end of the lifter rotates with the drill pipe while the upper end does not rotate, so that the rotary stress of the drill pipe is minimized. At present, domestic and foreign rotary drilling rigs are not installed with dynamic pulleys, so the wire rope has a large single rope tension. This should be equipped with wire ropes with good flexibility, good abrasion resistance, anti-rotation and good extrusion resistance. Especially for multi-layer winding of the front winch reel, it is recommended to use the same twist direction of the wire rope, in order to avoid the inner strand to produce marks.

Selection of wire rope diameter

The service life of the wire rope mainly depends on the size of the rope groove and the correct choice of the ratio between the diameter of the wire rope and the diameter of the reel.

Rotary drilling rigs usually choose: D/d≥20, D/φ≥250.

Where: d is the diameter of the bottom of the reel or pulley; D is the diameter of the wire rope; φ is the diameter of the outermost steel wire of the wire rope.

Matching the shape and diameter of the wire rope and the rope groove of the drum

When the wire rope is wound on the reel after a few layers, in the winding intersection and mutual contact parts will be subject to concentrated pressure and friction. In order to minimize wear and prolong the service life of the wire rope, it is recommended to cut off the section fixed on the reel after the rope has been used for some time. In this way, the section in good condition will replace the original wear position. This cutting operation should be carried out periodically in heavy-duty hoisting systems without waiting until the wire rope is completely damaged. The kind of wire rope that can support the pressure and friction between the spirals should be selected, so it should be a steel-cored, multi-stranded wire rope. Wire rope and reel rope groove matching parameters should be determined in accordance with the following formula: p = 1.15 × D (D maximum of 10mm rope); p = 1.12 × D (D maximum of 20mm rope); p = 1.11 × D (D more than 20mm rope); h = 0.4 × D; r = 0.55 × D. Where: D is the diameter of the wire rope; P is the center of the rope groove; H is the rope groove height; R is the rope groove radius. R is the radius of the rope groove.

Wire rope and pulley rope groove shape and diameter of the matching

Reasonable selection of the size of the pulley rope groove for the service life of the wire rope is critical. Pulley rope groove diameter must be larger than the nominal diameter of the wire rope, the bottom must be smooth, rounded, no bumps, and there should be a complete and proportionate sides. Pulley rope groove do not have to consider reducing the lateral pressure of the wire rope, its diameter must always be larger than the diameter of the wire rope. Pulley rope groove size parameters as shown in Figure 3, the correct rope groove size parameters must be calculated according to the following formula (size error of 0 to 4%):

The minimum diameter of the new pulley rope groove φmin = 1.05D;

Maximum diameter of the new pulley rope groove φmax = 1.10D;

Recommended diameter of new pulley rope groove φ2 = 1.08D;

The side opening angle of the rope groove should be 30°～60°, which is larger than the value of the inclination angle.

It is very dangerous to use worn and damaged wire rope, and it is necessary to check the wear and tear of the wire rope as well as any damage frequently. Once the wire rope breaks during work, the harm caused can be devastating to the entire rig or pile hole, so attention must be paid to the inspection and maintenance of the wire rope when using the drilling rig. With the increase of the working hours of the machine, the wire rope will be worn out continuously, so it is necessary to check its use status every shift.

Observe the lubrication of the wire rope

Wire rope is usually lubricated during processing, including surface and internal lubrication, which can protect the wire rope from corrosion and avoid internal steel wire and dry friction, but also lubricate the internal and external surfaces of the wire rope in motion. The initial lubrication can be maintained for a longer period of time. When it is observed that the wire rope lubrication is poor or lack of lubricant, the need for timely oiling. Lubrication should pay attention to the different degree of wear and tear of the grease used is also different.

① When the wire rope slides on the pulley or rolls on the drum, SAE30W is generally used, which can penetrate the gap of the rope for effective lubrication.

② When the wire rope is severely worn, use high viscosity grease lubrication to reduce mechanical wear, such as high viscosity oil or light grease containing graphite and molybdenum disulfide bonding additives.

③ When the wire rope comes into contact with loose abrasive materials (mud, sand, etc.), the lubricating oil (grease) on the outside of the rope will stick to these objects, resulting in severe wear of the wire rope and pulley. When encountering this situation, the surface of the wire rope must be cleaned and lubricated in time.

Methods of lubricating the wire rope: continuous bath of the rope, i.e., let the rope slide through the container with lubricating oil, and use a cloth to remove the excess oil brought out on the rope; use a cloth or a brush to brush oil or grease on the rope; lubricate the rope by spraying it with oil with a spray gun.

Observe the fatigue of the wire rope

Wire rope will also slowly fatigue in long time use. The aging process can be expressed simply as follows: wear - bending - corrosion and drag - fatigue - plastic deformation - wire fracture - wire rope breakage. Check the fatigue of the main method is to observe the internal steel wire rope breakage and wire rope bending deformation. Wire rope appears the following several common situations should take the necessary measures:

① when the wire rope is found to have several strands of steel wire fracture on the outside of the wire rope, it must be changed in time for the wire rope, otherwise it will be very dangerous.

② when the discovery of wire rope strand deformation, that is, there are several strands of wire rope from the inner layer of steel wire to the outer layer protruding, this situation indicates that the wire rope has been a great deal of local plastic deformation, it is easy to bring up heavy loads for a long time to produce the phenomenon of collapse, you must immediately change the rope.

③When the wire rope spiral twisted very tight and the outermost layer of steel wire appears a lot of burrs, or a part of the wire rope thinning, need to change the rope immediately.

In the construction process, should be strictly in accordance with the norms of operation, regular inspection of the wire rope wear and corrosion, and seriously do a good job on-site maintenance and maintenance, in order to fully explore the potential of the use of steel wire rope, and further improve the service life of the wire rope, so as to reduce the cost, improve efficiency, safety construction, and to improve the comprehensive economic benefits of construction enterprises.

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