Research on Steel Wire Arrangement Rules and Structural Performance Effects of Steel Cord Conveyor Belts

Abstract:

        Steel cord conveyor belts are core equipment in heavy-load continuous conveying scenarios such as mining, ports, power, and metallurgy. Their load-bearing skeleton is formed by high-precision arranged galvanized steel cords vulcanization-bonded with specialty rubber. The arrangement mode, spacing precision, layer structure, and twisting parameters of steel wires and steel cords directly determine the tensile strength, operating stability, tear resistance, and service life of the conveyor belt. These are core technical points that distinguish steel cord conveyor belts from ordinary fabric conveyor belts. Combining national standards and engineering application practices, this paper systematically expounds the standardized steel wire arrangement rules for steel cord conveyor belts and deeply analyzes the influence of arrangement parameter deviations on the mechanical properties, operating state, and safety performance of conveyor belts, providing technical reference for conveyor belt manufacturing, quality inspection, and working condition adaptation.

1. Introduction
        Compared with traditional canvas and polyester fabric-core conveyor belts, steel cord conveyor belts use high-strength galvanized steel cords as the longitudinal load-bearing body. Relying on the bonding, cushioning, and protective functions of the rubber medium, they offer advantages such as high tensile strength, low elastic elongation, impact resistance, stable operation, and suitability for long-distance conveying. They are widely used in various heavy-load, long-distance, and high-intensity continuous conveying conditions. The overall performance of the conveyor belt is not determined solely by the steel wire material and cord specifications; standardized, high-precision steel wire arrangement structure is the core prerequisite for ensuring uniform mechanical performance, structural stability, and safe reliability.

        In actual production, operation, and maintenance, problems such as uneven steel cord arrangement, excessive spacing, layer displacement, and disordered twisting can easily cause stress concentration, local deformation, splice failure, longitudinal tearing, and other faults, greatly reducing equipment service life and even causing safety accidents. Based on the GB/T 28267 series of national standards and industry technical specifications, this paper systematically sorts out the core arrangement rules for steel wires in steel cord conveyor belts and quantitatively analyzes the influence of arrangement parameters on the comprehensive performance of conveyor belts, providing theoretical support for refined production and efficient operation and maintenance in the industry.

2.Core Steel Wire Arrangement Rules for Steel Cord Conveyor Belts

        The steel wire arrangement of steel cord conveyor belts is divided into two dimensions: the twisted arrangement of wires within a single steel cord and the overall steel cord array arrangement in the belt body. The former determines the mechanical characteristics of a single cord, while the latter determines the overall load-bearing performance of the conveyor belt. Both are subject to strict standardized constraints and are core process criteria for manufacturing.

    2.1 Rules for the Twisted Arrangement of Wires Inside a Single Steel Cord

        Steel cords specially used for conveyor belts are twisted from high-carbon galvanized steel wires and have a non-loosening, high-concentricity structure. The internal wire arrangement follows fixed process parameters to ensure uniform single-cord strength, suitable flexibility, and excellent fatigue resistance. First, lay length standardization: the strand lay length of the steel cord is strictly controlled at 6–8 times the cord diameter, and the wire lay length within the strand is uniform and consistent, with no sudden deviation along the entire length, avoiding local stress concentration. Second, concentric structural arrangement: the central strand wires and the central wires of the outer strands are appropriately thickened, and the outer wires are evenly arranged in a spiral around the central strand, with no offset, overlapping, or uneven gaps, ensuring symmetrical force on the cord cross-section. Third, forming stability: all steel cords must be made into a non-loosening structure, with no scattered or warped wires after cutting, ensuring the flatness and straightness of the subsequent overall array arrangement.

    2.2 Overall Steel Cord Array Arrangement Rules in the Belt Body

        All longitudinal load-bearing steel cords inside the belt body are embedded in parallel in the core rubber layer, forming a single-layer uniform array structure. This is the core arrangement form of steel cord conveyor belts, and national standards have clear mandatory requirements for its straightness, spacing precision, and layer position.

        First, straightness rules. All steel cords must maintain straight extension in the longitudinal direction of the belt body, with no bending, offset, or twisting throughout, eliminating wavy arrangement, ensuring that the longitudinal force of the conveyor belt is transmitted completely along the axial direction of the cords and avoiding lateral component forces. Second, spacing precision rules. The horizontal spacing of steel cords is a core control parameter. The nominal spacing of steel cords in conventional mining conveyor belts is 12 mm, and the allowable deviation is strictly controlled within ±1.5 mm. In addition, the number of steel cords with excessive deviation shall not exceed 5% of the total number, ensuring arrangement uniformity at the batch level. Third, uniform layer position rules. All steel cords must be in the same horizontal plane, with no vertical height differences or upward/downward displacement. The upper and lower sides of the cords must be covered with core rubber and cover rubber of uniform thickness, with no local unevenness in rubber layer thickness. Fourth, splice arrangement rules. Steel cord splices are strictly prohibited within 10 m of the belt end. The number of splices in a single steel cord shall not exceed 1, and the number of splices within every 10 m of conveyor belt shall not exceed 1. The proportion of steel cords containing splices in the belt body shall not exceed 5% of the total number, avoiding weak strength zones caused by concentrated splice arrangement.

    2.3 Auxiliary Arrangement Rules for Special-Structure Conveyor Belts

        For tear-resistant and high-strength special conveyor belts, in addition to the longitudinal steel cord array, transverse reinforcement structures are added to form a reticulated reinforcement system. The transverse reinforcement and longitudinal steel cords are arranged crosswise at an angle of 30°–90° and can be placed above, below, or on both sides of the longitudinal steel cords. The transverse and longitudinal cords are completely isolated by rubber layers with no direct contact or friction. Without affecting the longitudinal tensile performance, this greatly improves the puncture resistance and longitudinal tear resistance of the conveyor belt. Some preferred type B conveyor belts use a composite arrangement structure of elastic transverse members combined with longitudinal steel cords, further optimizing the overall elasticity and impact resistance of the belt body.

3.Core Effects of Steel Wire Arrangement Rules on the Performance of Steel Cord Conveyor Belts

        The arrangement precision and structural form of steel wires and steel cords directly determine the mechanical distribution, operating state, durability, and safety factor of the conveyor belt. Even a small arrangement deviation can create a performance weakness. The specific effects are reflected in five core dimensions.

    3.1 Effects on Tensile Strength and Force Uniformity

        A uniform and symmetrical steel cord array arrangement allows the overall load of the conveyor belt to be evenly shared by all steel cords. Each cord bears essentially the same force, fully exploiting the load-bearing potential of high-strength steel wires and ensuring that the nominal tensile strength of the conveyor belt meets the standard. If horizontal spacing is uneven or local density is imbalanced, steel cords in dense areas will be overloaded, while steel cords in sparse areas will bear insufficient force, causing severe imbalance in load distribution. Overloaded cords remain in an overstressed state for a long time and are prone to fatigue fracture, while local load-bearing gaps reduce the effective load-bearing area of the belt body, directly causing attenuation of the overall tensile strength of the conveyor belt and making it unable to meet heavy-load conveying requirements.

        Compared with vertical layer position deviation, uneven horizontal spacing has a more significant effect on the force borne by the conveyor belt and is the primary arrangement defect causing local strength failure and reduced overall load-bearing capacity of the belt body. In addition, uneven lay length or structural eccentricity of wires within a single cord can cause asymmetric force on the steel cord itself. When the cord bears load alone, local fracture may occur and gradually trigger chain failure.

    3.2 Effects on Splice Strength and Connection Stability

        The vulcanized splice of a steel cord conveyor belt is the weakest link in the entire machine. The arrangement precision of steel cords at the splice directly determines the splice bonding strength and service life. Under standard arrangement conditions, the steel cord spacing in the splice area is uniform and the layer position is flat. The core rubber can evenly penetrate the gaps between cords, maximizing the bonding area between rubber and steel wires and making the bonding stress distribution uniform. The splice strength can reach more than 90% of the belt body strength.

        If the arrangement has problems such as spacing deviation, cord displacement, or height unevenness, defects such as uneven rubber filling, local bonding voids, and cord extrusion and overlapping will occur during splice vulcanization, leading to bonding stress concentration and a significant reduction in local bonding strength. During equipment operation, the splice area repeatedly bears tensile, bending, and impact loads and is highly prone to debonding and cracking from weak bonding points, gradually causing splice delamination, tearing, and complete detachment. This is a major cause of conveyor belt splice failure and equipment shutdown. Strictly controlling the horizontal arrangement precision of steel cords is key to improving splice reliability and extending splice service life.

    3.3 Effects on Operating Stability and Deformation Characteristics

        Regular straight parallel arrangement makes the longitudinal elastic elongation of the conveyor belt uniform and consistent. During operation, the belt body has no mistracking, jitter, or local bulging, making it suitable for high-speed and long-distance conveying conditions. Disordered steel cord arrangement, uneven spacing, and local bending or displacement will cause large differences in elastic deformation in different areas of the conveyor belt. During operation, the force and deformation of the belt body are not synchronized, resulting in slight mistracking, vertical jitter, wavy deformation, and other phenomena.

        Under long-term operation, uneven deformation will aggravate friction and wear between the conveyor belt and pulleys and idlers, causing excessively fast local wear and uneven thickness of the belt body. It will also cause material deviation and spillage, reducing conveying efficiency. In addition, vertical height deviation of cords will lead to uneven belt thickness, inconsistent force cushioning during operation, increased dynamic load fluctuations, significantly higher equipment noise and vibration, and aggravated mechanical loss of the entire machine.

    3.4 Effects on Tear Resistance, Impact Resistance, and Durability

        Standardized uniform arrangement makes the thickness of the internal rubber buffer layer of the conveyor belt uniform and the combination between steel cords and rubber tight, effectively buffering material impact and resisting puncture damage from sharp materials. When the conveyor belt is subjected to impact or puncture loads, uniformly arranged steel cords can quickly disperse local stress, avoid stress concentration, and greatly improve impact and tear resistance.

        If steel cord arrangement is uneven in density, sparse areas have an overly thick rubber layer and insufficient rigidity, resulting in weak impact resistance and easy puncture or tearing by sharp materials. Dense areas have an overly thin rubber layer and excessive rigidity, resulting in insufficient toughness; under impact, they are prone to debonding between steel wires and rubber and cord extrusion damage. At the same time, local stress concentration caused by arrangement deviation will accelerate steel wire fatigue aging, corrosion, and wear, greatly shortening the overall service life of the conveyor belt. The transverse-longitudinal composite reticulated arrangement structure can further optimize stress dispersion and structurally prevent longitudinal tearing faults.

    3.5 Effects on Safety Performance and Operation and Maintenance Costs

        Faults caused by non-compliant steel cord arrangement, such as local fracture, splice failure, longitudinal tearing, and mistracking wear, not only affect the continuous operation of the conveying system but also pose major safety hazards. Under heavy-load conditions such as mines and ports, sudden tearing or breaking of the conveyor belt can cause material collapse, equipment jamming, and even safety accidents.

        From the perspective of operation and maintenance, early damage and local failure caused by arrangement defects will greatly increase the frequency of conveyor belt repair and replacement and raise equipment operation and maintenance costs and downtime losses. Strictly implementing standardized arrangement rules can avoid structural defects at the source, improve the operating stability and safety factor of the conveyor belt, extend equipment service life, and reduce comprehensive operation and maintenance costs.

4.Common Causes of Arrangement Defects and Key Points for Optimal Control

    4.1 Common Causes of Arrangement Defects

        During production and manufacturing, insufficient precision of forming equipment, uneven tension control, deviation in vulcanization process parameters, and manual operation errors are the main reasons for excessive steel cord spacing, layer displacement, and insufficient straightness. At the same time, unqualified twisting quality of the steel cords themselves and failure to meet non-loosening performance requirements will cause cord deformation and misalignment after arrangement, leading to overall arrangement disorder.

    4.2 Key Points for Production and Application Optimization

        On the production side, national standard arrangement specifications must be strictly implemented, the consistency of steel cord tension must be precisely controlled, and the straightness and spacing precision of cords during forming must be ensured, with the proportion of out-of-tolerance cords strictly controlled. The vulcanization process should be optimized to ensure uniform rubber filling and avoid arrangement defects in the splice area. On the application side, conveyor belts with arrangement structures suitable for the working conditions should be selected. For heavy-load and tear-prone conditions, reticulated composite reinforcement structures should be preferred. During operation and maintenance, belt deformation and splice conditions should be regularly inspected, and early damage caused by arrangement defects should be promptly identified.

5.Conclusion

        The steel wire arrangement of steel cord conveyor belts is a core process that balances structural rationality and performance stability. The standardized implementation of single-cord twisted arrangement, overall array arrangement, and special-structure composite arrangement is the foundation for ensuring high strength, high stability, and long service life of conveyor belts. The horizontal spacing precision, straightness, and layer consistency of steel cords are core indicators of arrangement control. Small deviations in these indicators directly affect the force uniformity, splice strength, operating stability, and damage resistance of the conveyor belt and are key structural factors causing equipment faults and safety hazards.

        In the context of high-quality development of the industry, only by strictly following standardized arrangement rules, precisely controlling production process precision, and optimizing arrangement structure design according to working conditions can the comprehensive performance of steel cord conveyor belts be improved at the source, operation and maintenance losses be reduced, and safe, efficient, and stable operation of heavy-load continuous conveying systems be ensured. In the future, with the upgrading of intelligent forming processes, high-precision, deviation-free, and customized steel wire arrangement structures will further drive steel cord conveyor belts toward high durability, high safety, and intelligent iteration and upgrading.