Wire rope use and maintenance
(1) Use qualified products to ensure that their mechanical properties and specifications meet the design requirements, and do not use scrap wire ropes.
(2) Ensure a sufficient safety factor and, if necessary, do a force calculation.
(3) Lifting and luffing mechanisms shall not use wire ropes with braided lengths.
(4) The take-up device is in any position, and a safety ring of 2 to 3 turns must be kept on the reel.
(5) Avoid the intersection of the two steel ropes and the pressure of the stacking during use to prevent knotting, twisting, excessive bending and scratching.
(6) Keep the surface of the wire rope clean and in good lubrication.
(7) Adhere to the inspection of the wire rope for each work shift (including parts that are difficult to see and inaccessible).
The connection and fixing of the wire rope should be consistent with the requirements of use and meet the corresponding strength and safety requirements.
(1) rope card connection
1) The joint strength is not less than 85% of the breaking force of the wire rope.
2) The number of rope cards meets the requirements according to the diameter of the rope (see Table 3).
3) The rope clamp should be on the long side of the rope; the pitch of the rope should not be less than 6 times the diameter of the rope.
(2) braided connections
1) The joint strength is not less than 75% of the breaking force of the wire rope.
2) The braiding length should not be less than 15 times the diameter of the wire rope and should not be less than 300 mm.
(3) Other connections: Connections such as wedge wedge sleeve, tapered sleeve casting method and aluminum alloy sleeve compression method shall meet the corresponding technical requirements, and the joint strength shall reach the breaking tension of the steel wire rope.
During the use of the wire rope of the scrap wire rope, due to strong tensile stress, metal fatigue caused by repeated bending and extrusion, wear caused by motion, etc., after a period of use, wire rope defects will occur, which are manifested in broken wire and rust wear. , deformation and other aspects. In general, the destruction of the wire rope first occurs on the outer wire. In one of the following cases, it will be scrapped.
(1) Broken wire and wear indicators
1) When the number of broken wires reaches the value in Table 4.
Note: The number of broken wires in the table refers to thin steel wires, and each of the thick steel wires is equivalent to 1.7 thin steel wires.
2) When the steel wire rope is corroded or worn, the number of broken wires in Table 4 shall be reduced according to Table 5, and shall be scrapped according to the number of broken wires after reduction.
3) The number of scrapped broken wires of steel wire ropes carrying hot metal or dangerous crystals is taken as half of the number of broken wires of general crane wire ropes, including the reduction of abrasion of steel wire surface.
4) Broken wire ends. When there is a broken wire at or near the end of the rope, even if the number is small, if the length of the rope is allowed, the broken part should be cut off and reinstalled.
5) The degree of local aggregation of broken wires. If the broken filaments are concentrated in a rope length less than one pitch, or concentrated in any strand, even if the number of broken filaments is less than the values listed in the above table, it should be scrapped.
6) The growth rate of broken wires. When the number of broken wires is gradually increased and the time interval is shortened, the growth of broken wires should be carefully checked and recorded, the law should be determined, and the date of scrapping should be determined.
7) One strand of the wire rope is broken.
8) Wear. When the outer wire is worn up to 40%, or the wire diameter is reduced by 7% due to wear.
9) Corrosion. Corrosion pits appear on the surface of the wire, or the rope diameter increases or decreases due to rusting of the strands.