Specifications and parameters of steel wire rope

1、 Talk about the steel wire raw materials used in the production of steel wire rope

Steel wire is the most basic raw material of steel wire rope. The quality of steel wire fundamentally affects the quality of steel wire rope. Therefore, no matter how your steel wire rope technology and production process are, the raw materials can not pass the test. No matter how well you do the follow-up work, it can not make up for this barrier!

The raw materials of steel wire rope are generally high-quality and hard wire, sometimes called wire rod or wire rod, rather than ordinary ordinary wire or high wire. Some Pugao wires are used to produce iron wire, which is different from the properties of steel wire. The iron wire is soft and the steel wire is hard. The raw materials for producing iron wire are generally Q195 or Q235, while the production of steel wire generally uses high carbon steel. The steel grades are mostly between 45 # - 85 #.

The diameter of steel wire in the production of steel wire rope is generally from 0.2mm to 5mm, and the most used is 0.2mm to 3mm. The tensile strength of steel wire for rope making is from 1470mpa to 1960mpa, and the most used is 1570 to 1770mpa. The surface of steel wire for rope making is divided into galvanized, smooth and stainless steel, all of which are smooth steel wire rope, galvanized steel wire rope and stainless steel wire rope.

2、 Type of wire rope

The steel wire rope is made of many high-strength carbon steel wires with a diameter of 0.3-3mm, which are first twisted into strands, and then several strands are twisted around the rope core to form a rope. There are many kinds of wire ropes. According to the different winding methods, they can be divided into four types: left co twisting, right co twisting, left alternating twisting and right alternating twisting. Right alternating twisting wire ropes are commonly used in lifting operations.

According to the different materials of the steel wire rope core, it can be divided into three types: hemp core, asbestos core and metal rope core. Hemp core steel wire rope is often used in lifting operations. The hemp core is soaked with lubricating oil to reduce the friction and prevent corrosion between the rope strand and the steel wire.

According to the different strands and number of wires of the steel wire rope, it can be divided into 6: × 19、6 × 37 and 6 × 61 three kinds, the most commonly used in lifting operations is 6 × 19 and 6 × 37 steel wire rope.

According to the different surface treatment of the steel wire, it can be divided into two types: smooth surface and plating bowl. The smooth surface steel wire rope is commonly used in lifting operations.

According to the classification of wire rope strand structure, it can be divided into point contact rope, line contact rope and surface contact rope.

The diameter of each layer of steel wire of the point contact rope is the same, but the pitch of each layer is different, so the steel wires cross each other to form point contact. The contact stress is very high in the work, and the steel wire is easy to wear and break, but the manufacturing process is simple.

The thickness of the steel wire in the strand of the wire contact rope is different. The thin steel wire is placed in the groove of the thick steel wire, and the thick and thin steel wires are in line contact. Because the contact stress of wire contact wire rope is small, the life of wire rope is long and the flexibility is increased. Since the wire contact wire rope is relatively dense, the breaking force of wire contact wire rope with the same diameter is larger. The same direction twisted wire rope with the same wire diameter in the rope strand is also a wire contact rope.

The shape of the steel wire in the strand of the surface contact rope is special, and the steel wire with special section is used, and the steel wires are in surface contact. It has the advantages of smooth appearance, good corrosion resistance and wear resistance, and can withstand large lateral force; But it is expensive, so it can only be used in special occasions.

3、 Specification parameters of steel wire rope

For general lifting operation, 6 in GB / t8918-1996 steel wire rope can be used × 19 and 6 × 37 steel wire rope. See Table 1 and table 2 for its specifications.

Table 1 breaking force of steel wire rope

Tensile strength of diameter steel wire rope / MPa

a wire rope

/Mm steel wire

/mm 1400 1550 1700 1850 2000

Total breaking force of steel wire / kn

6.2 0.4 20.00 22.10 24.30 26.40 28.60

7.7 0.5 31.30 34.60 38.00 41.30 44.70

9.3 0.6 45.10 49.60 54.70 59.60 64.40

11.O 0.7 61.30 67.90 74.50 81.10 87.70

12.5 0.8 80.10 88.70 97.30 105.50 114.50

14.O 0.9 101.00 112.00 123.00 134.00 114.50

15.5 1.O 125.00 138.50 152.00 165.50 178.50

17.O 1.1 151.50 167.50 184.00 200.00 216.50

18.5 1.2 180.00 199.50 219.00 238.00 257.50

20.O 1.3 21150 234.00 257.00 279.50 302.00

21.5 1.4 245.50 271.50 298.00 324.00 350.50

23.O 1.5 281.50 312.00 342.00 372.00 402.50

24.5 1.6 320.50 355.00 389.00 423.50 458.00

26.O 1.7 362.00 400.50 439.50 478.00 517.00

28.O 1.8 405.50 499.00 492.50 536.00 579.50

31.O 2.O 501.00 554.50 608.50 662.00 715.50

34.O 2.2 606.00 671.00 736.00 801.00 —

37.O 2.4 721.50 798.50 876.00 953.50 —

40.O 2.6 846.50 937.50 1025.00 1115.00 —

Table 2 breaking force of steel wire rope

Tensile strength of diameter steel wire rope / MPa

a wire rope

/Mm steel wire

/mm 1400 1550 1700 1850 2000

Total breaking force of steel wire / kn

8.7 0.4 39.00 43.20 47.30 51.50 55.70

11.O 0.5 60.00 67.50 74.00 80.60 87.10

13.O 0.6 87.80 97.20 106.50 116.00 125.00

15.O 0.7 119.50 132.00 145.00 157.50 170.50

17.5 0.8 156.00 172.50 189.50 206.00 223.00

19.5 0.9 197.50 218.50 239.50 261.00 282.00

21.5 1.O 243.50 270.00 296.00 322.00 348.50

24.O 1.1 295.00 326.50 358.00 390.00 421.50

26.O 1.2 351.00 388.50 426.50 464.00 501.50

28.O 1.3 412.00 456.50 500.50 544.50 589.00

30.O 1.4 478.00 529.00 580.50 631.50 683.00

32.5 1.5 548.50 607.50 666.50 725.00 784.00

34.5 1.6 624.50 691.50 758.00 825.00 892.00

36.5 1.7 705.00 780.50 856.00 931.50 1005.00

39.O 1.8 790.00 875.00 959.50 1040.00 1125.00

43.O 2.O 975.50 1080.00 1185.00 1285.00 1390.00

47.5 2.2 1180.00 1305.00 1430.00 1560.00 —

52.O 2.4 1405.00 1555.00 1705.00 1855.00 —

56.O 2.6 1645.00 1825.00 2000.00 2175.00 —

Marking of wire rope

At present, the steel wire rope used on the crane is mainly ordinary structural steel wire rope, rope 6 × 19 and rope 6 × 37。 According to the national standard round strand steel wire rope (gb1102-74), the marking method of steel wire rope is as follows:

For example, steel wire rope 6 × 37-15.0-170-i (one nail, one plating and one right crossing) (gb1102-74)

This means that the round strand steel wire rope is twisted by 6 strands, and the structural form of the strands is point contact. Each strand has 37 steel wires, fiber rope core, and the diameter of the steel wire rope is 15.0mm. It is made of No. I group a coated bowl steel wire with a nominal tensile strength of 1700mpa. The twisting direction of the steel wire rope is right alternating twisting.

Selection of steel wire rope

When the wire rope has the same diameter, the lower the nominal tensile strength, the more wires in each rope, and the smaller the wire diameter, the better the flexibility of the rope, but the wire rope is easy to wear. On the contrary, the thicker the diameter of the steel wire in each rope, the worse the flexibility of the steel wire rope and the wear resistance of the steel wire rope. Therefore, different types of wire rope have different application ranges. According to the actual needs of lifting operation, generally, the following principles can be considered for the selection of steel wire rope:

(1)6 × 19 steel wire rope is used as cable wind rope, stay cable and lifting sling, which is generally used in places with small bending load or abrasion.

(2)6 × 37 steel wire rope is used for binding various articles, equipment, threading pulley group and making lifting slings during lifting operation. Applicable when the rope is bent.

(3)6 × 61 steel wire rope is used to bind various articles. Rope?? Small rigidity, easy to bend, used for bearing??? Not a big place.

The steel wire rope twisted in the same direction has a flat and soft surface, good bending fatigue resistance and durability; Its disadvantage is that the rope strand is easy to be loose at the disconnection of the rope head, and it is easy to rotate and curl and twist when hanging heavy objects. Therefore, it is not suitable to use it alone in hoisting. The alternating twisted steel wire rope is commonly used in hoisting operations.

6、 Stress calculation of steel wire rope

There is a certain limit to the maximum tensile force that a certain specification of steel wire rope can bear. Beyond this limit, the steel wire rope will be damaged or broken. Therefore, the stress of the steel wire rope needs to be calculated in the work.

（1） Breaking control force of steel wire rope

The breaking force of the steel wire rope can be found in Table 1 and 2. Considering that the twisting of the steel wire rope causes uneven stress on each steel wire, the breaking force of the whole steel wire rope shall be calculated according to the following formula:

SP= ΨΣ Si

Where SP -- breaking force of steel wire rope, kn;

Σ Si -- total breaking force of steel wire provided in the specification table of steel wire rope, kn;

Ψ—— Reduction coefficient of uneven twisting of steel wire, for 6 × 19 rope, Ψ= 0.85; Right, 6 × 37 rope, Ψ= 0.82; Right, 6 × 61 rope, Ψ= 0.80。

However, at the work site, there is generally no chart data, and accurate calculation is not required. At this time, the following formula (only for data estimation, non-standard formula) can be used to estimate the breaking force of steel wire rope:

Where, SP -- breaking force of steel wire rope, N;

D - diameter of steel wire rope, mm.

（2） Safety factor of steel wire rope

In order to ensure the safety of lifting operation, the allowable tension of steel wire rope is only a fraction of its breaking force. The ratio of breaking force to allowable tension is the safety factor. The following table lists the safety factors of wire ropes for different purposes.

The table shows the safety factor of steel wire rope

Safety factor of use

Used as cable, wind rope and drag rope 3.5 mechanical driven lifting equipment 5-6

Manual driven lifting equipment 4.5 used as slings (no bending) 6-7

Used as binding slings (8-10) and used as manned elevators (14)

Allowable torsion of wire rope

P=SP/K

Where, P -- allowable tensile force of steel wire rope, N;

SP -- breaking force of steel wire rope, N;

K - safety factor of steel wire rope.

Example: Model 6 × What is the allowable tension of 37-26 steel wire rope when it is used as binding rope?

Solution: SP = 500d2 = 500 × 262=338000(N)

When used as binding rope, take k = 10, then

P=SP/K=338000/10=33800（N）

7、 Scrapping standard of steel wire rope

When the wire rope is damaged to a certain extent, it must be scrapped according to the regulations. The scrapping standards are as follows:

① When the number of broken steel wires in each pitch (also known as lay pitch, which refers to the axial length of any strand of the steel wire rope wound for one week) exceeds the number specified in Table 2.4, it shall be scrapped. The number of broken wires of the steel wire rope is not large, but it should also be scrapped when the number of broken wires increases rapidly.

② When the wear or corrosion of the steel wire of the steel wire rope reaches or exceeds 40% of the original steel wire diameter, it shall be scrapped. Those within 40% shall be degraded according to table 2.5. When the pitted surface formed by the corrosion of the outer surface of the whole wire rope reaches the level that can be easily seen by the naked eye, it shall be scrapped.

The table shows the number of scrapped broken wires of steel wire rope

The table shows the reduction factors

Steel wire surface wear or corrosion (%) reduction coefficient (%) steel wire surface wear or corrosion disc (%) reduction coefficient (%)

10 85 25 60

15 75 30-40 50

20 70 > 40 o

③ The wire rope shall be scrapped if it has been burnt or local arc.

④ The wire rope shall be scrapped in case of flattening deformation, strand or wire extrusion, cage distortion, local increase of rope diameter, kinking and bending.

⑤ The wire rope shall be scrapped when the rope core is damaged and the rope diameter is significantly reduced (up to 7%).

⑥ For the steel wire rope lifting hot metal or dangerous goods, the number of scrapped broken wires shall be half of the number of broken wires of the steel wire rope of the general crane, including the reduction of wear or corrosion on the surface of the steel wire rope.

8、 Use, maintenance and repair of wire rope

① The wire rope shall be uncoiled correctly. When uncoiling the steel wire rope, it is necessary to prevent the steel wire rope from being twisted and damaged due to strength reduction. The steel wire rope shall be tied tightly to prevent loosening.

② The steel wire rope shall not be overloaded and cannot work under impact load. The speed shall be stable during operation.

③ When binding or lifting objects, the wire rope shall avoid direct contact with the sharp corners and edges of the objects, and the contact shall be padded with wood blocks, linen or other cushions.

④ It is forbidden to contact the wire rope with the wire to avoid being damaged or electric shock. Thermal insulation measures shall be taken when approaching high-temperature objects.