The reasons for the failure of inclined shaft hoisting wire ropes were analyzed in detail. The corrosion and mechanical damage mechanisms during the use of mine hoisting and transportation wire ropes were analyzed in detail. Based on the analysis results, targeted preventive countermeasures were made to improve the wire ropes. The purpose is to ensure the safe operation of the wire rope.
1. Problem
A local coal mine has an annual design production capacity of 300,000 tons, and there are 5 lifting winches above 2Mt underground, and the wire rope model is 6△ (26) 24.51670 light On the other hand, due to insufficient understanding of steel wire ropes, a sports car accident with a broken rope occurred in 2004; after using the new steel wire rope for 20 days, it was found that there were uniform pitting pits on the surface, and the development was rapid; in addition, in the management of other small Similar problems exist in winch wire ropes. In response to the above accidents and phenomena, the damage to the wire rope was carefully analyzed and studied, and some regular understandings were obtained, and countermeasures were studied to guide the improvement of transportation management and ensure safe production.
2. Reasons for replacement of wire rope failure
Causes of wire rope failure:
(1) Serious corrosion of the wire rope causes failure;
(2) Severe wear and tear of the wire rope causes failure;
(3) Failure of the steel wire rope caused by bending and knotting;
(4) Failure of the steel wire rope due to excessive impact force.
3. Causes of failure and protection
1. Failure caused by severe corrosion of the wire rope
The environment in which the wire rope for inclined shaft lifting is used is relatively harsh, and it is often exposed to the sulfuric acid water in the wellbore. Corrosion causes the surface layer to peel off, resulting in black pits and grooves. Practice has proved that the loss of strength and toughness due to corrosion greatly exceeds the effects of normal wear and fatigue. Acidic and alkaline spray water and airflow will not only wash away the grease on the surface and inside of the steel wire rope, but will also cause the steel wire rope to rust, the rope core to rot, the strands and the wire ropes to wear and squeeze, and the loss of steel wire strength and toughness will be aggravated.
(1) Strengthen inspections and carefully analyze the severity of wire rope corrosion. According to Article 408 of the "Coal Mine Safety Regulations": Mine steel wire ropes must not be used for lifting personnel when the wires are damaged such as blackening, embroidery, pitting, etc. When the steel wire rope is severely rusted, or pitted to form grooves, or the outer steel wire is loose, it must be replaced immediately regardless of the number of broken wires or the change in rope diameter;
(2) Strengthen the daily maintenance of the steel wire rope . Apply anti-corrosion oil regularly to ensure that the water channel in the shaft is smooth, and clean the water in the ground roll ditch in time to prevent the wire rope from running in the water; Zinc steel wire rope.
2. Serious wear of the wire rope causes failure
In the inclined shaft hoisting system, the wear of the wire rope is the main factor of failure. During the operation of the steel wire rope, the wear caused by its outer periphery contacting the surface of the ropeway, bottom plate, rope stopper and other objects is external wear. The cross section of the steel wire rope will be reduced, the outer surface of the steel wire will be smoothed, and the breaking load will be reduced accordingly. When the steel wire rope is outside If the diameter is worn below the requirements of the "Coal Mine Safety Regulations", use should be stopped and a new rope should be replaced.
(1) Strengthen the maintenance of floor rollers and promptly replace damaged ones. For inclined shafts with heavy lifting tasks, it is best to use floor rollers made of rubber nylon materials;
(2) Strengthen Lubricate sheaves and pulleys to reduce the friction coefficient;
(3) Strengthen the maintenance of the winch drum wood and excessive rope grooves to ensure that the wire ropes are arranged neatly and do not bite the ropes, and reduce local wear.
(4) Avoid single-week wear, and achieve uniform wear as much as possible over the entire length, that is, full-circle wear;
(5) Single-week wear is not avoided, and replacement is required regularly Winch wire rope ends, such as large winches, should be worn evenly once a quarter.
(6) Change the cast iron sheave of the inclined shaft to the polyurethane sheave to reduce the rigid wear of the wire rope as much as possible.
3. Failure caused by bending and knotting of wire ropes
During the use of inclined shaft steel wire ropes, phenomena such as bending, knotting, twisting and snubs often occur. If not dealt with in time, they will Will wear and damage the wire rope. If there is too much remaining rope at the hook hook in the parking lot, it is easy for the wire rope to become coiled. If not handled in time, bending or twisting will occur at this time. During operation, the bending and protruding parts wear out quickly, and wire breakage is easy to occur and develop rapidly until the wire rope is scrapped.
(1) The winch driver operates according to regulations to avoid the phenomenon of residual rope. After the residual rope bends and turns, the transport handle hook worker should handle it in time;
(2) Left and right twisting When changing the wire rope in the direction of the drum, pay attention to the direction of the rope when winding it on the drum, and follow the direction of the rope. When winding up the rope, the wire ropes on the drum should be arranged neatly, leaving no gaps in the middle, thereby preventing job hopping and rope biting;
(3) When bending protrusions occur, take timely measures to deal with them, such as using a handle The rope puller can straighten the wire rope, chop the slippery head or turn the large rope around to extend the service life of the wire rope. 4. Excessive impact force on the wire rope causes failure
There are many stress factors on the inclined shaft lifting wire rope, including factors within the lifting system and external factors that affect the impact force.
(1) During operation, acceleration and deceleration are too large to generate inertia force. When the inertia force is too large, it will have a direct impact on the steel wire rope and even penetrate holes or shed cans.
(2) If the braking force is too large when transporting heavy objects, the wire rope will be subject to a greater impact when lowered; if the braking force is too large and lifted up, a loose rope will be generated, which will accelerate down under the action of the heavy object. , causing the wire rope to be suddenly tightened and subject to impact;
(3) When double rollers were lifted, the underground switchman's incorrect operation caused the same hook phenomenon, causing the lifting containers to collide with each other and cause impact;
(4) The disrepair of the track bed causes the lifting container to fall, and the jamming phenomenon causes impact on the wire rope.
Measures to be taken:
(1) The start-up or deceleration speed of the winch must be strictly limited and the provisions of the "Coal Mine Safety Regulations" must be followed. Lifting personnel must not exceed the limit when lifting heavy objects in inclined shafts. When the safety gate is activated, under normal circumstances, the speed limiting device must be used correctly to avoid artificial limitation of acceleration and deceleration;
(2) Reasonable adjustment The braking force of the brake shoe ensures the normal operation of the secondary brake and alleviates the impact caused by excessive braking force;
(3) Strengthen employees' safety awareness and avoid misoperation. At the same time, in order to prevent containers from colliding with each other, alarm signals on the same side should be installed to prevent the steel wire rope from being impacted by external forces;
(4) Strengthen the maintenance of transportation and lifting-related facilities. When the steel wire rope is impacted by external forces, it should be immediately Parking inspection. If the damaged section of the wire rope does not meet the specified requirements, it should be chopped off or replaced immediately.
IV. Conclusion
The inspection, maintenance and scrapping of steel wire ropes used in coal mines involve the safety of coal mine production and the safety of life and property. In order to further improve the reliability and service life of the wire rope operation, it is necessary to twist the wire rope with uniform quality, stable performance and advanced structure. It also needs correct use and maintenance.
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