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In the process of crane lifting operations, wire ropes play a crucial role. As wire ropes are critical components of cranes, it is essential for operators to utilize them appropriately, select the right type of overhead crane wire rope based on the working environment, and master the correct inspection methods. This approach effectively enhances the overall work quality and ensures the stability and safety of crane operations. This article analyzes the selection and inspection methods of overhead crane wire ropes, aiming to continuously improve the work system and optimize the performance of crane wire ropes in practical applications.

Selection of Overhead Crane Wire Ropes

Wire ropes are a critical component of cranes. If the selection is improper, it will affect the overall work progress and lead to serious safety accidents. Based on the working standards for crane wire ropes, during the selection process, the safety factor of the wire rope must first be considered to ensure it complies with relevant national standards. If the safety factor of the wire rope does not meet the standards, it will pose potential safety hazards. Secondly, during the selection process, the price of the wire rope must also be taken into account. To ensure overall work efficiency, operators need to analyze the cost of wire ropes required for the specific working environment of the crane, thereby improving the overall cost-effectiveness. Finally, close attention must be paid to the quantity of wire ropes, which should be determined based on actual work requirements.

1. Determining the Safety Factor of Wire Ropes

In the process of selecting overhead crane wire ropes, it is necessary to consider the type of crane and the safety factor of the wire rope. Factors such as the crane’s luffing and hoisting mechanism grade should be taken into account to determine the safety grade of the wire rope. When determining the safety parameters of crane wire ropes, operators must establish the safety factor in accordance with relevant regulatory requirements.

2. Strength Calculation of Wire Ropes

In the process of selecting overhead crane wire ropes, it is necessary to use the corresponding formulas to calculate the diameter of the wire rope, ensuring the scientific basis for the selection.

F₁≥F_maxS

• F₁​: Minimum breaking force of the wire rope
• F_max​: Maximum static working force of the crane wire rope
• S: Safety factor of the wire rope

F₀≥(F_max/Φ_i)S

• F₀​: Total breaking force of the wire rope
• Φ_i​: Conversion coefficient for the breaking force of the crane wire rope

Based on the calculation results, it can be determined whether the strength of the wire rope meets the work requirements, ensuring the safety and stability of crane operations.

3. Structure of Wire Ropes

The contact methods of crane wire ropes mainly include point contact, line contact, and surface contact. Operators need to select the appropriate wire rope based on the operating parameters of the crane to ensure a scientifically sound selection. For example, during the selection process, operators can determine the structural form of the wire rope through methods such as line contact, cross-lay, and round-strand with a steel core. This helps ascertain whether the selected wire rope can meet the operational requirements of the crane.

Proper Use of Overhead Crane Wire Ropes

During crane operations, wire ropes play a vital role. Therefore, it is essential to handle the selection and use of wire ropes correctly. If the rotational torque of the inner and outer strands of the wire rope lacks balance, the lay length of the wire rope will be disrupted, leading to slackness in the wire rope. This, in turn, affects the load-bearing capacity of the crane wire rope.

Correct Unreeling Method for Wire Ropes

Crane wire ropes are primarily unrolled or installed in coils. When unrolling or installing wire ropes, various measures should be taken to prevent the wire rope from rotating inward or outward, as this may cause looping, kinking, or bending, rendering the wire rope unusable. This includes unspooling from a rope coil or a reel. During actual operations, when unspooling the wire rope, random pulling should be avoided to prevent twisting or looping of the crane wire rope. To avoid such undesirable tendencies, the wire rope should be unspooled in a straight line under the minimum allowable slack.

During the installation of wire ropes, if the working environment and conditions permit, it is essential to ensure that the wire rope always twists in the same direction. Specifically, wire ropes unspooled from the upper part of the reel should enter the upper part of the crane or hoist drum, while wire ropes unspooled from the lower part of the reel should enter the lower part of the crane or hoist drum. If the leading end of the wire rope is counterclockwise, the coil should be formed in a counterclockwise direction. During the winding process of crane wire ropes, the entire coil should be mounted on a dedicated rotating bracket. During the unspooling stage, the wire rope on the hoisting mechanism drum should be rotated uniformly, and the direction of the wire rope and the reel should also be aligned.

Correct Method for Threading Wire Ropes

For the proper application of crane wire ropes, it is crucial to select the appropriate lay direction of the wire rope, especially during the threading process. Special attention must be paid to the lay direction of the crane wire rope. When changing or replacing the crane wire rope, the position of the end in the rope groove and the fixed position on the upper end of the drum should be noted.

• When using left-lay crane wire ropes, the wire rope should be wound from left to right, with the wire rope exiting from the lower side.
• When using right-lay wire ropes:
  • In the first scenario, the wire rope should be wound from left to right, with the wire rope exiting from the upper side of the drum.
  • In the second scenario, the wire rope should be wound from right to left, with the wire rope exiting from the lower side of the drum.

Inspection Methods for Overhead Crane Wire Ropes

Inspeksi visual

After determining the model and quantity of crane wire ropes, operators must conduct a visual inspection. During this process, they need to check whether the wire ropes exhibit any signs of damage. The current crane wire rope market includes counterfeit and substandard products, which cannot guarantee the reliability of wire rope applications. Therefore, during the visual inspection, it is essential to ensure that all crane wire ropes are free from quality issues and to avoid using defective wire ropes.

During the visual inspection, operators can employ a comparative analysis method. In construction projects, when selecting crane wire ropes, it is advisable to establish long-term partnerships with wire rope manufacturers. By comparing unused crane wire ropes with newly purchased ones, operators can determine whether there are any quality issues with the wire ropes’ appearance. If the overall condition of the crane wire rope is acceptable but some parts show signs of wear, it can still be put into use as long as the wear does not affect its direct application performance.

Manual Inspection

When crane load-bearing wire ropes are used in actual environments and conditions, their outer surfaces come into contact and friction with surfaces such as pulley grooves and drum exteriors, leading to external wear. This wear causes the rope diameter to thin and shrink, and may also result in the outer wires becoming smooth, broken, or even causing strand fractures. These issues reduce the cross-sectional area of the load-bearing wire rope, thereby affecting its tensile strength. Daily manual inspections primarily include visual observation and caliper measurement methods. Below are the specific inspection details:

• Broken Wire Inspection: During crane operations, wire ropes need to be replaced regularly because broken wires are a common issue during use. Operators must systematically analyze the internal and external broken wire conditions to ensure the rigor of the inspection process.
• End Broken Wires: Severe wear at the ends of the wire rope can lead to breakage. If broken wires are detected, it indicates that the wire rope has aged and needs to be replaced promptly.
• Broken Wire Growth Rate: As the usage time of overhead crane wire ropes increases, the number of broken wires accumulates, and the interval between broken wires shortens. Therefore, the application time of the wire rope should be calculated based on the broken wire condition.
• Rope Diameter Reduction: Damage to the rope core reduces the diameter of the crane wire rope and weakens its strength, affecting the stress balance of the wire rope strands. Thus, the condition of the rope core must be checked during actual work, and issues should be identified and addressed promptly.
• Internal and External Wear: Under pressure, repeated contact between the crane wire rope and the drum groove or pulley groove causes external wear, reducing the wire rope’s strength and decreasing its cross-sectional area and diameter. To resolve this, operators must replace the wire rope with a new one in good condition.
• Corrosion: Cranes primarily operate in external environments. If the lubrication of the wire rope is poor or it operates in high-temperature and humid conditions, corrosion may occur. Upon detecting such issues, operators must lubricate the wire rope.
• Deformation: Under external forces, overhead crane wire ropes may suddenly break. Operators must replace the wire rope promptly in such cases.
• Inspection of Connecting Fittings: During the connection of wire rope ends, operators must check the firmness of various connecting devices. Through manual inspection, they should optimize and replace wire ropes based on their actual condition.

To reduce oversight in crane wire rope inspections, operators should conduct inspections in batches. This ensures that inspection details are thoroughly implemented and overall work quality is maintained. To guarantee the effectiveness of manual inspections, a review process must be implemented. All overhead crane wire ropes should undergo at least two rounds of review to avoid any issues that could affect actual work performance.

Instrument Inspection

During the instrument inspection of overhead crane wire ropes, flaw detectors can be utilized, primarily employing the magnetic flux leakage (MFL) method to detect broken wire defects in crane wire ropes. In the actual operation phase, operators need to magnetize the wire rope axially using a magnetic field and perform non-destructive testing through magnetic-sensitive detection devices. Finally, by analyzing the magnetic flux leakage signals, it can be determined whether the crane wire rope has broken wire issues. Additionally, defects can be detected based on the magnetic permeability of the crane wire rope. Operators need to use balanced magnetic circuit sensors to measure the magnetic flux of the wire rope and determine changes in the wire rope’s cross-sectional area based on the signals.

To maximize the effectiveness of the flaw detector, sensors should be installed near the crane’s fixed pulley and drum. By analyzing and storing defect signals from the wire rope, signal simulation can be performed, and a computer monitor can be used to obtain information such as the position, length, and number of broken wires in the crane wire rope. If issues are detected, the monitor will issue an alarm, and specific inspection parameters can be printed out.

Compared to manual inspection methods, instrument inspection provides more accurate data and higher detection efficiency, facilitating a comprehensive understanding of defects in crane wire ropes and precise determination of their load capacity and lifespan. Additionally, online inspection methods allow operators to clearly understand the actual condition of the crane wire rope. However, instrument inspection also has limitations. For example, it cannot identify issues such as corrosion or bending in crane wire ropes, nor can it systematically inspect the position of the wire rope ends and related connecting fittings. Therefore, in practical inspection work, operators need to choose the appropriate inspection method based on specific usage conditions.

Maintenance of Overhead Crane Wire Ropes

During the lifting phase of a crane, significant fluctuations in its load-bearing capacity can cause varying degrees of tensile stress between each layer of wire rope on the drum. This situation often leads to pressure gap issues, causing the outer layer of wire rope to bear excessive pressure, which is then transmitted to the layers below. If the crane wire rope is in a slack state, the outer layer may experience localized deformation, disrupting the arrangement of the wire rope and accelerating its wear, thereby reducing its service life. When such issues occur, the following measures should be taken:

Manual Rope Arrangement

When the above problems arise, operators must immediately stop the equipment and address the issue through manual rope arrangement. Although this method is relatively inefficient, it can release all tangled wire ropes, thereby improving and optimizing the wire rope’s performance.

Requirements for Wire Rope Arrangement on the Drum

The user unit should replace the crane wire rope based on the actual lifting height of the equipment. The wire rope on the drum should be used effectively without releasing excess rope. When the lifting tool is at its lowest working position, the wire rope wound on the drum (excluding the fixed end coils) should have no fewer than 2 coils (for tower cranes and mobile cranes, no fewer than 3 coils). For mechanical parking equipment, when the carrier or car tray is at the lowest working position, the wire rope wound on the drum (excluding the fixed end coils) should have no fewer than 2 coils.

Wire Rope Lubrication

Lubricating the wire rope can enhance its performance. During use, overhead crane wire ropes are subjected to both tensile forces and pulley compression, generating heat due to friction. Depletion of the wire rope’s lubricant can lead to corrosion, negatively impacting its quality. Additionally, surface roughness caused by external wear can affect the anti-corrosion performance of the inner wire ropes, potentially leading to breakage. Therefore, operators should regularly clean and lubricate the crane wire rope to ensure its lubrication effectiveness.

Inspection and Recording

In addition to lubrication, the wear and broken wire conditions of the wire rope should be inspected during use. If any issues are detected, the wire rope should be replaced promptly with a new one, and the relevant situation should be reported to ensure the safe operation of the equipment.

Kesimpulan

To fully leverage the role of overhead crane wire ropes, it is essential to select the appropriate type of wire rope, adopt scientific inspection methods, and ensure proper use and maintenance. This approach guarantees the safe operation of cranes and prevents safety accidents.

Referensi: Selection and Inspection Methods for Crane Wire Ropes

Cindy

Ada apa: +86-19137386654

Surel: cindywang@hndfcrane.com

Saya Cindy, dengan 10 tahun pengalaman kerja di industri derek dan telah mengumpulkan banyak pengetahuan profesional. Saya telah memilih derek yang memuaskan bagi 500+ pelanggan. Jika Anda memiliki kebutuhan atau pertanyaan tentang derek, jangan ragu untuk menghubungi saya, saya akan menggunakan keahlian dan pengalaman praktis saya untuk membantu Anda memecahkan masalah!