標準編號:	GB/T 36698-2018
中文名稱:	帶式輸送機設計計算方法
英文名稱:	Basis for calculation of belt conveyors
中標分類:	J81    輸送機械
行業分類:	GB    國家標準
ICS分類:	53.040.10 53.040.10    輸送機 53.040.10
發布機構:	國家市場監督管理總局 國家標準化管理委員會
發布日期:	2018-09-17
實施日期:	2019-4-1
標準狀態:	valid
翻譯語言:	英文
文件格式:	PDF
中文字符數:	54000 字
翻譯價格(元):	3780.0
交付時間:	付款后 1 個工作日

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. This standard is developed in accordance with the rules given in GB/T 1.1-2009. This standard was proposed by China Machinery Industry Federation. This standard is under the jurisdiction of National Technical Committee 331 on Continuous Handling Equipment of Standardization Administration of China (SAC/TC 331). Basis for calculation of belt conveyors 1 Scope This standard specifies the basis for design calculation of belt conveyors, which is used to determine the basic parameters and layout design of their main components (such as driving unit, braking unit, take-up unit, pulley, idler and conveyor belt). This standard is applicable to belt conveyors used for conveying bulk materials. This standard is not applicable to the basis for design calculation of special belt conveyors such as cable, pipe and air cushion belt conveyors. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 7984 Conveyor belts of textile construction for general use GB/T 9770 Steel cord conveyor belts for general use GB/T 10595 Belt conveyors GB/T 14521 Terms of continuous handling equipment GB/T 28267.1-2012 Steel cord conveyor belts - Part 1: Design, dimensions and mechanical requirements for conveyor belts for general use GB/T 28267.2 Steel cord conveyor belts - Part 2: Preferred belt types GB/T 28267.3 Steel cord conveyor belts - Part 3: Special safety requirements for belts for use in underground installations GB/T 28267.4 Steel cord conveyor belts - Part 4: Vulcanized belt joints GB/T 31256 Conveyor belts - Specification for rubber- or plastics-covered conveyor belts of textile construction for underground mining GB 50431 Code for design of belt conveyor engineering 3 Terms and definitions For the purposes of this document, the terms and definitions given in GB/T 14521 and the following apply. 3.1 starting for inherent characteristics mode where the belt conveyor is started according to the inherent mechanical characteristics (relationship between rotational speed and torque) of driving unit 3.2 starting for motion control starting mode where the belt conveyor is controlled according to the set starting acceleration or speed curve 3.3 nominal capacity conveying capacity used for belt conveyor design according to the requirements of engineering design 4 Symbols, definitions and units Symbols, definitions and units are given in Table 1. Table 1 Symbols, definitions and units Symbol Definition Unit A Cross-sectional area of carried materials m2 A1 Cross-sectional area of the upper part of carried materials m2 (mm2)a A2 Cross-sectional area of carried materials when θ = 0° (cross-sectional area of lower part of carried materials) (3-roller idler set) Cross-sectional area of inverted trapezoidal part on outer roller (5-roller idler set) m2 (mm2)a A3 Cross-sectional area of inverted trapezoidal part on inner roller (5-roller idler set) m2 (mm2)a AN Cross-sectional area of carried materials under nominal capacity m2 AGr Effective contact area between the working face cleaner and the conveyor belt mm2 AGr1 Effective contact area between the non-working face cleaner and the conveyor belt mm2 B Belt width mm C Additional resistance coefficient — D Diameter of pulley mm D1 Datum diameter of pulley determined according to the service life conditions of the conveyor belt mm ELB Longitudinal elastic modulus of the conveyor belt N/mm F Tension or resistance of the conveyor belt N Fa Inertial force caused by acceleration/deceleration under unsteady operating condition N FbA Inertial resistance of conveyed materials and/or frictional resistance between conveyed materials and the conveyor belt in feeding section N Fc1 Conveyor belt tension at the start point of convex or concave curved section N Fc2 Conveyor belt tension at the end point of convex or concave curved section N FD Average tension of conveyor belt on the pulley N FE Indentation rolling resistance per unit length obtained based on the test results N/m Ff Frictional resistance between the conveyed materials and the side plates of the skirt board in feeding section N FH Major resistance N Fgl Frictional resistance between the conveyed materials and the side plates of the skirt board outside the feeding section N FHs Locking force N FI Bending resistance of conveyor belt when winding the pulley N Fr Frictional resistance of the working surface cleaner N Frl Frictional resistance of non-working face cleaner N FN Additional resistance N Fp Frictional resistance of the tripper N FR Rotating resistance of idler per unit length obtained based on the test results N/m FS Special resistance N Fsbn Frictional resistance of buffer bed (sliding bed) N FSk Frictional resistance of apron seal of skirt board in feeding section N FSk1 Frictional resistance of apron seal of skirt board outside the feeding section N FSp Take-up tension of take-up pulley N FSt Lifting resistance of conveyed materials (which includes the lifting resistance of conveyor belt in section resistance calculation) N Fl Pulley bearing resistance N FT Tension of conveyor belt at characteristic point N FT1 Tension at the point of contact between the conveyor belt and the pulley N FT2 Tension at the separation point between the conveyor belt and the pulley N FTm Average tension of the conveyor belt N FTr Peripheral driving force of the pulley N FU Traveling resistance (equal to the peripheral driving force of the pulley) N FV Vector sum (numerical value) of the conveyor belt tension acting on the pulley and the weight of pulley rotor N Fw Additional bending resistance of convex or concave curved section N Ft Forward tilt resistance N ΔFTm The difference between the average conveyor belt tension, FTm, and the minimum conveyor belt tension, FTmin N Im,N Nominal capacity by mass kg/s Im,th Theoretical capacity by mass kg/s IV,N Nominal capacity by volume m3/s IV,th Theoretical capacity by volume m3/s J Moment of inertia of pulley kg·m2 JD Moment of inertia of driving unit rotor on the high-speed shaft of the reducer kg·m2 Jf Moment of inertia of flywheels kg·m2 L Conveyor length m Ka Scraper coefficient N/m PA Total power of driving pulley required to overcome traveling resistance under steady operating condition kW PM Total power of driving motor kW PM,N Rated power of driving motor kW Q Nominal capacity t/h Ra Curvature radius of vertical concave curved section m (mm)a Re Curvature radius of vertical convex curved section m (mm)a S Safety coefficient relative to nominal tensile strength of conveyor belt — S0 Safety coefficient of conveyor belt determined with joint process conditions considered — S1 Safety coefficient determined with expected life and working stress of conveyor belt considered — Smin Minimum safety coefficient relative to the minimum nominal tensile strength of conveyor belt — a Acceleration or deceleration m/s2 b Effective width of conveyor belt (theoretical width of conveyor belt carrying materials) m (mm)a b1 Width of materials stacked on conveyor belt mm b2 Width of materials on 3-roller idler set mm bS Width of conveyor belt on side rollers (only for 2-roller and 3-roller idler sets) mm bSch Clear width between skirt boards m c0 Calculation coefficient used to determine the minimum diameter of pulley — cK Coefficient of minimum joint fatigue strength determined based on edge tension of conveyor belt — cR Calculation coefficient for converting the rotating mass of idler to the equivalent mass on the periphery of the idler — cRank Coefficient of active lateral pressure — cS Speed correction coefficient of simulated friction coefficient — CSchb Coefficient of additional resistance caused by material disturbance in the feeding section — cT Temperature correction coefficient of simulated friction coefficient — cTd Coefficient used to determine the datum value of the minimum length of the troughing transition section — cε Calculation coefficient of forward tilt resistance — d0 Inner diameter of pulley bearing mm dB Thickness of tensile element (core) of conveyor belt (excluding the upper and lower coatings of conveyor belt) mm dR Diameter of idler m e The napierian base (e=2.718 28…) — eK Height difference from neutral datum line to the edge of conveyor belt mm eM Height difference from the neutral datum line to the center of the conveyor belt mm fbase Datum value of simulated friction coefficient — Δfs Correction of simulated friction coefficient related to belt speed — ΔfT Correction of simulated friction coefficient related to temperature — f Simulated friction coefficient — fi Simulated friction coefficient for each section of the upper and lower branches — fr Rotating frequency of rollers in an idler set at a certain belt speed Hz fp Approximate inherent vibration frequency of cross-sectional of conveyor belt Hz fRMBT Pulley load factor (determined by the maximum tension and nominal tensile strength of conveyor belt) — g Gravitational acceleration (g=9.81 m/s2) m/s2 h Height difference (h > 0 in upward case; h<0 in downward case) m hk0 Distance from the plane formed by the edges of both sides of the conveyor belt to the lowest plane of the trough m hk1 Distance between the plane formed by the edges of both sides of the conveyor belt and the upper generatrix plane of the pulley m hTr Distance between the upper generatrix plane of the pulley in the troughing transition section and the lowest plane of the trough (the height of pulley elevation) m i Drive ratio — k Conveyor belt tension relative to conveyor belt width (average conveyor belt tension over belt width) N/mm kK Tension per unit width at the edge of conveyor belt N/mm kM Tension per unit width in the central area of the conveyor belt N/mm kN Nominal tensile strength of conveyor belt N/mm kN,min Minimum nominal tensile strength of conveyor belt N/mm hrel Sag of conveyor belt (ratio of the maximum sagging amount of conveyor belt between idler sets to the spacing between idler sets) — kt Datum fatigue strength of conveyor belt joint (tensile strength of conveyor belt with strength reduction of conveyor belt joint considered) N/mm kt,rel Relative datum fatigue strength of conveyor belt joint — Δk Difference in tension per unit belt width between the edge and the central area of the conveyor belt N/mm l Length of section m l2 Length of 2 middle rollers (5-roller idler set) mm lb Length of the skirt board in the feeding section m lgl Length of the skirt board outside the feeding section m lK Edge length of conveyor belt in troughing transition section m lM Length of the middle idler of 3-roller idler set mm (m)a lR Spacing between idler sets m ls1 Contact length between outer idlers and materials m lTd Length of troughing transition section m lTd,eff Effective length of troughing transition section of steel cord conveyor belt m ΔlTd Additional length of transition section, namely, lTd,eff-lTd of steel cord conveyor belt m lw Length of turnover section of the conveyor belt m mf Equivalent mass of flywheel converted to the periphery of the pulley kg mD Equivalent mass of the pulley, flywheel (if set), driving and braking units converted to the periphery of the pulley kg mL Equivalent mass of conveyor belt, material and idler on belt conveyor line kg ∑m Sum of equivalent mass of conveyor belt, material and idler on belt conveyor line and equivalent mass of pulley, driving and braking units on belt conveyor line converted to the periphery of the pulley kg n Number of sections of belt conveyor divided — nR Maximum allowable rotating speed of roller under steady operating condition of belt conveyor r/min pA Starting coefficient related to driving pulley — pA,0 Starting coefficient related to driving — pB Braking coefficient related to braking pulley — pB,0 Braking coefficient related to braking — pD Power distribution coefficient — pGr Pressure exerted by the working face cleaner on the conveyor belt N/mm2 pGr1 pressure exerted by the non-working face cleaner on the conveyor belt N/mm2 pSk Effective positive pressure per unit length between conveyor belt and seal N/m pBp Allowable specific pressure of the conveyor belt N/mm2 pBs Allowable specific pressure under the steel wire rope of steel cord conveyor belt N/mm2 q Coefficient of estimation of major resistance — qB Mass per unit length of conveyor belt kg/m qR Mass per unit length of idler rotor kg/m qG,i Mass per unit length of material on a section kg/m s1 Thickness of conveyor belt mm sSp Working distance of take-up pulley m v Belt speed m/s v0 Speed of the material fed to the conveyor belt in the conveying direction m/s sB Braking distance m t1 Spacing between steel wire ropes of conveyor belt mm tB Braking time s zD Number of driving or braking pulley Pcs. zM Number of motors (driving units) Pcs. zR Number of idler sets on a section (in upper or lower branch) Set zTr Number of pulleys Pcs. zε Number of forward tilting idler sets on a section (in upper or lower branch) Set α Wrap angle ° or rad αc Central angle corresponding to the convex or concave curved section rad β Equivalent angle of move of materials used to calculate the cross-sectional area of materials ° θ Angle of move (angle of repose) of conveyed materials ° δ Conveying angle of inclination (δ>0 in upward case and δ<0 in downward case) ° ε Angle of inclination of side roller (top rake) ° φ Effective filling coefficient — φSt Cross-sectional reduction coefficient of theoretical total carrying cross-sectional area during inclined conveying — φSt1 Cross-sectional reduction coefficient of theoretical cross-sectional area of the upper part of carried materials during inclined conveying — λ Trough angle of idler set and outer roller (4-roller and 5-roller idler sets) ° λ1 Trough angle of 2 middle rollers (4-roller and 5-roller idler sets) ° μ Friction coefficient between conveyor belt and pulley — μ1 Friction coefficient between conveyor belt and conveyed material — μ2 Friction coefficient between the conveyed materials and the side plates of the skirt board — μ3 Friction coefficient between conveyor belt and idlers — μ4 Friction coefficient between conveyor belt and cleaner — μ5 Sliding friction coefficient between conveyor belt and sealing rubber — μ6 Friction coefficient between buffer bed and conveyor belt — ρ Bulk density of conveyed materials kg/m3 ΔεK Additional elongation (positive or negative) at the edge of conveyor belt relative to natural axial concave or convex curved section of conveyor belt — ΔεK∞ The limit value of ΔεK at the edge of conveyor belt with long curved section — ΔεM Additional elongation (positive or negative) at the central area of conveyor belt relative to natural axial concave or convex curved section of conveyor belt — ΔεM∞ The limit value of ΔεM at the central area of conveyor belt with long curved section — Δε∞ Difference in elongation between the central area and the edge of the conveyor belt with long curved section — η1 Total efficiency of all driving links between motor shaft and pulley shaft in motor mode — η2 Total efficiency of all driving links between motor shaft and pulley shaft in generator mode a Units in brackets are used in some formulae. ? 5 Capacity by volume and by mass 5.1 Theoretical cross-sectional area of materials The theoretical capacity by volume and by mass of belt conveyor are determined by the theoretical cross-sectional area and traveling speed of materials stacking on the conveyor belt. The cross-sectional area of materials depends on the angle of move of the conveyed materials, the specific structural type of the idler set and the feeding mode. In calculating the theoretical capacity by volume and by mass, this standard assumes that the cross section of the conveyed materials has upper surface with parabolic contour line. Figure 1 shows a cross section of materials on the supporting conveyor belt of a common troughing 3-roller idler set. Figure 1 Theoretical cross section of horizontally-carried materials conveyed by 3-roller idler set The theoretical cross-sectional area of carried materials is determined by the length, lM, of middle roller, the trough angle, λ, the effective width, b, of the conveyor belt, and the angle of move, θ. The effective width, b, is the width of the conveyor belt with a certain margin reserved to avoid spillage; it can be calculated using Formulae (1) and (2): b=0.9B-50 (if B≤2,000) (1) b=B-250 (if B>2,000) (2) where, B——the belt width, mm; b——the effective width of conveyor belt (theoretical width of conveyor belt carrying materials), mm. As for the belt conveyor with horizontal curves, the effective width of the conveyor belt may be reduced due to the inclined arrangement of rollers. As for the materials carried by supporting conveyor belt of 3-roller idler set on a horizontally-arranged belt conveyor, the theoretical cross-sectional area, Ath, calculated based on the angle of move θ may be determined based on the sum of cross-sectional areas, A1,th and A2,th, (see Figure 1); Formulae (3), (4) and (5) shall be used for calculation: (3) (4) Ath=A1,th+A2,th (5) where, Ath——the theoretical cross-sectional area of carried materials, m2; A1,th——the theoretical cross-sectional area of the upper part of carried materials, m2; A2,th——the theoretical cross-sectional area of carried materials when θ = 0° (cross-sectional area of lower part of carried materials), m2; lM——the length of the middle idler of 3-roller idler set, m; θ——the angle of move of materials, °; λ——the trough angle of idler set, °; b——the effective width of conveyor belt (theoretical width of conveyor belt carrying materials), m. When used to calculate the cross-sectional area A1,th, the equivalent angle of move β shall be calculated using Formula (6): (6) where, β=θ/1.5. The angle of move of materials depends on the characteristics of conveyed materials and factors of belt conveyors, such as length and belt speed. If empirical value of angle of move is not available, the following may be chosen: ——for materials with normal fluidity, take 0≤θ≤20°; ——for materials with high fluidity, take 20°≤θ≤30°. Theoretical cross-sectional area of materials carried by 2-roller idler set shall be calculated by substituting lM=0 into Formulae (3) and (4); Theoretical cross-sectional area of materials carried by 1-roller idler set shall be calculated by substituting lM=0 and λ=0 into Formulae (3) and (4). See Annex A for the calculation of the theoretical cross-sectional area, Ath, of materials carried by 1-roller, 2-roller, 4-roller and 5-roller idler sets respectively. Theoretical capacity by volume shall be calculated using Formula (7) based on the theoretical cross-sectional area of carried materials: IV,th=Ath·v (7) Theoretical capacity by mass shall be calculated using Formula (8): Im,th=ρAth·v (8) where, IV,th——the theoretical capacity by volume, m3/s; Im,th——the theoretical capacity by mass, kg/s; v——the belt speed, m/s; ρ——the bulk density of conveyed materials, kg/m3. 5.2 Cross-sectional reduction coefficient during inclined conveying When a belt conveyor feeds uniformly and travels horizontally and straightly, its theoretical cross section of materials can be fully utilized. ? Under the influence of material weight, internal friction angle and other factors, the area of the upper part, A1,th, shown in Figure 1 will be reduced. When the belt conveyor is well centered, uniformly feeds and conveys materials with small particle size and the maximum angle of inclination, δmax on the belt conveyor line ≤θ, the reduction coefficient of the upper part shall be calculated using Formula (9): (9) where, φSt1——the cross-sectional reduction coefficient of theoretical cross-sectional area, A1,th, of the upper part of carried materials during inclined conveying, dimensionless; δmax——the maximum angle of inclination on the belt conveyor line, °; θ——the same as that in Formula (3). The reduction coefficient, φSt, of theoretical cross-sectional area of carried materials during inclined conveying shall be calculated using Formula (10): (10) where, φSt——the cross-sectional reduction coefficient of theoretical cross-sectional area, Ath, of the carried materials during inclined conveying, dimensionless. If Formulae (9) and (10) are used, attention shall be paid to that the maximum angle of inclination during inclined conveying can only be equal to the angle of move, θ. In this case, only cross-sectional areas A2,th is used for material conveying. 5.3 Nominal capacity and effective filling coefficient When nominal capacity by mass, Im,N, is given, nominal capacity by volume, IV,N, shall be calculated using Formula (11): (11) where: Im,N——the nominal capacity by mass, kg/s; IV,N——the nominal capacity by volume, m3/s. The cross-sectional area required shall be calculated using Formula (12): (12) where: AN——the cross-sectional area of carried materials required under nominal capacity, m2. The effective filling coefficient of belt conveyor shall be calculated using Formula (13): (13) where: φ——the effective filling coefficient of belt conveyor, dimensionless. The effective filling coefficient φ depends on: ——characteristics of conveyed materials; ——particle size and composition; ——angle of move θ; ——operating conditions of belt conveyor; ——uniformity of feeding; ——line layout of conveyor; ——conveying angle of inclination; ——reserve of conveying capacity. The effective filling coefficient, φ, is used to evaluate whether the theoretical sectional area, Ath, of materials matches with the sectional area required under nominal capacity. In this standard, some calculation parameters are selected on premise that the effective filling coefficient φ satisfies 0.7<φ<1.1; otherwise, the calculation parameters selected shall be corrected; in some cases, the effective filling coefficient will be out of the above range, in which the specific values will be determined based on the test data and the experience of the engineer. The mass per unit length of materials under nominal capacity shall be calculated using Formula (14): or qG=φρAth (14) where, qG——the mass per unit length of materials under nominal capacity, kg/m. Nominal capacity shall be calculated using Formula (15): (15) where, Q——the nominal capacity, t/h. 6 Traveling resistance and power consumption under steady operating condition 6.1 Calculation principle As a general rule, before calculating the traveling resistance, it needs to estimate the datum values of the parameters used (such as mass per unit length and simulated friction coefficient of conveyor belt and idler). These values shall be confirmed or corrected according to actual selection during calculation. In general, repeated calculations shall be carried out to achieve calculation results that are completely applicable to specific applications. The traveling resistance, FU, generated under steady operating condition is the total resistance generated by friction, gravity and other resistances together. The power, PA, required by the driving pulley of the belt conveyor is obtained by multiplying the sum of traveling resistances generated by the upper and lower branches by the traveling speed, v, as shown in Formula (16): (16) where, PA——total power on periphery of driving pulley required to overcome traveling resistance under steady operating condition, kW; FU——the sum of traveling resistances generated by the upper and lower branches, N. For the purpose of calculation, the traveling resistances of belt conveyor are classified into: ——major resistance FH (see 6.2); ——additional resistance FN (see 6.3); ——lifting resistance FSt (see 6.4); ——special resistance FS (see 6.5). The sum, FU, of traveling resistances is equal to the peripheral driving force, FTr, of pulley transmitted from the driving pulley to the conveyor belt, as shown in Formula (17): (17) where, FTr——the sum of peripheral driving force of pulley, N; FU,o,i, FU,u,i——the traveling resistance on sections i of the upper and lower branches respectively, N; no, nu——the number of sections divided in upper and lower branches respectively. ? Resistance shall be determined by section. The sectioning principle is to have the same calculation parameters in each section, such as the angle of inclination δi, the simulated friction coefficient, fi, the mass per unit length of materials, qG,i, and the mass per unit length of the idler rotor, qR,i, on each section in the upper and lower branches of the belt conveyor. To facilitate computer programming calculation, during the resistance calculation, the sections shall be numbered from the tail section to the head section of the belt conveyor, with subscripted i as the serial number of the section, the subscripted o as the upper branch and the subscripted u as the lower branch (see Figure 2), and pulley numbered as separate section. In the text below, for the sake of uniform expression, the pulley number is indicated by subscripted j, and the point of contact by subscripted T1 and the separation point by subscripted T2. (See Figures 5 and 6). 6.2 Major resistance 6.2.1 Calculation of major resistance The major resistance is generated over the entire length of the conveying lines of all belt conveyors. It includes rotating resistance of idler, indentation rolling resistance of conveyor belt, bending resistance of conveyor belt and internal friction resistance of materials. The major resistance shall be calculated separately for each section. In order to simplify the calculation of section resistance, the major resistance FH,i in each section of upper and lower branches shall be calculated based on the linear relationship between resistance and motion load, as shown in Formula (18): FH,i=lifig[qR,i+(qB+qG,i)cosδi] (18) where, FH,i——the major resistance on section i, N; li——the length on section i, N; fi——the simulated friction coefficient on section i, dimensionless; qR,i——the mass per unit length of the idler rotor on section i, kg/m; qB——the mass per unit length of conveyor belt, kg/m; qG,i——the mass per unit length of materials on section i, kg/m; δi——the conveying angle of inclination of section i, °; g——the gravitational acceleration, m/s2. To determine the conveyor belt tension, the major resistances, FH,o,i and FH,u,i, in sections of upper and lower branches respectively must be determined firstly (see 8.3). The major resistance of a belt conveyor is the sum of the major resistances, FH,o and FH,u, of upper and lower branches, as shown in Formula (19): (19) where: FH——the total major resistance of upper and lower branches, N; FH,o,i, FH,u,i——the major resistance on sections i of the upper and lower branches respectively, N; FH,o, FH,u——the sum of the major resistances of upper and lower branches respectively, N. Key: 0, 1, 2——characteristic points of conveyor line; lo,1, lo,2, lu,1, lu2——the lengths of sections 1 and 2 of upper branch and lower branch, respectively; FU,o,1, FU,o,2, FU,u,1, FU, u,2——the traveling resistance of sections 1 and 2 of upper and lower branches, respectively. Figure 2 Section division and traveling resistance of each section under steady operating condition In calculating the major resistance of each section, the effective filling coefficient, φ, of materials shall satisfy 0.7<φ<1.1. Otherwise, the datum values of calculation parameters given in this standard shall be corrected. The major resistance shall be calculated under extreme load conditions (nonuniform feeding, partial load and no load) if upward and downward sections are included on the line of belt conveyor, because the sum of resistances in this case may greatly exceed the resistance under steady operating condition. 6.2.2 Determination of simulated friction coefficient Choosing the simulated friction coefficient fi is more important than calculating the major resistance, because fi determines the major resistance, especially for belt conveyors with small lifting resistance. The simulated friction coefficient fi given in Table 2 may be used to calculate the major resistance of upper and lower branches. If measured or empirical value is unavailable, or only rough equipment parameters are available, the datum value of the simulated friction coefficient f may be selected according to the operating condition and structural characteristics given in Table 2. These datum values are obtained by summary based on a large number of measurements on the upper and lower branches and with the following restrictions considered:

Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Symbols, definitions and units 5 Capacity by volume and by mass 5.1 Theoretical cross-sectional area of materials 5.2 Cross-sectional reduction coefficient during inclined conveying 5.3 Nominal capacity and effective filling coefficient 6 Traveling resistance and power consumption under steady operating condition 6.1 Calculation principle 6.2 Major resistance 6.3 Additional resistance 6.4 Lifting resistance 6.5 Special resistance 6.6 Calculation method of total traveling resistance of belt conveyor 7 Design calculation of driving system 7.1 Contents of design calculation 7.2 Position of driving unit, specification and number of driving motor 7.3 Starting, braking and stopping 8 Calculation of tension and take-up tension of conveyor belt 8.1 Factors affecting conveyor belt tension 8.2 Conveyor belt tension 8.3 Traveling resistance and tension at characteristic point of upper and lower branch sections 8.4 Take-up tension and working distance of take up unit 8.5 Tension of conveyor belt at characteristic point of upper and lower branches 9 Tension distribution across the width of conveyor belt 9.1 Calculation principle 9.2 Troughing transition section 9.3 Curve section 10 Determination of tensile strength and coating thickness of conveyor belt 10.1 Selection principles 10.2 Calculation of break strength of conveyor belt 10.3 Determination of coating thickness of conveyor belt 11 Method for determination of minimum diameter of pulley 11.1 Principle 11.2 Determination based on the service life of conveyor belt 11.3 Determination based on allowable specific pressure of conveyor belt 12 Selection of idler and design of idler spacing 12.1 Calculation principle 12.2 Determination of roller diameter 12.3 Spacing between idler sets 12.4 Design to avoid resonance 13 Design of curvature radius of troughing transition section and vertical curved section 13.1 Calculation principle 13.2 Determination of minimum length of troughing transition section 13.3 Determination of minimum radius of vertical curved section 14 Design of turnover of the conveyor belt Annex A (Informative) Calculation of cross-sectional area of materials carried by 5-roller idler sets Annex B (Informative) Determination of total additional resistance based on additional resistance coefficient Annex C (Informative) Calculation of maximum conveyor belt tension for simply arranged belt conveyors Bibliography

帶式輸送機設計計算方法 1 范圍 本標準規定了帶式輸送機的設計計算，用于確定帶式輸送機主要部件(如驅動裝置、制動裝置、拉緊裝置、滾筒、托輥和輸送帶等)的基本參數與布置設計。 本標準適用于輸送散狀物料的帶式輸送機。 本標準不適用于鋼絲繩牽引帶式輸送機、管狀帶式輸送機、氣墊帶式輸送機等特種帶式輸送機的設計計算，其通用部分的設計計算可參照使用本標準。 2規范性引用文件 下列文件對于本文件的應用是必不可少的。凡是注日期的引用文件，僅注日期的版本適用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改單)適用于本文件。 GB/T 7984普通用途織物芯輸送帶 GB/T 9770 普通用途鋼絲繩芯輸送帶 GB/T 10595 帶式輸送機 GB/T 14521 連續搬運機械術語 GB/T 28267.1—2012 鋼絲繩芯輸送帶 第1部分：普通用途輸送帶的設計、尺寸和機械要求 GB/T 28267.2鋼絲繩芯輸送帶 第2部分：優選帶型 GB/T 28267.3 鋼絲繩芯輸送帶 第3部分：井下用輸送帶的特殊安全要求 GB/T 28267.4鋼絲繩芯輸送帶 第4部分：帶的硫化接頭 GB/T 31256輸送帶 具有橡膠或塑料覆蓋層的地下采礦用織物芯輸送帶規范 GB 50431 帶式輸送機工程設計規范 3術語和定義 GB/T 14521界定的以及下列術語和定義適用于本文件。 3.1 固有特性啟動starting for inherent characteristics 帶式輸送機按照驅動裝置固有的機械特性(轉速和轉矩關系)的啟動方式。 3.2 運動控制啟動starting for motion control 帶式輸送機按照設定的啟動加速度或速度曲線控制的啟動方式。 3.3 設計輸送量nominal capacity 根據工程設計要求的、用以進行帶式輸送機設計的輸送量。 4符號、含義與單位 表1給出了符號、含義與單位。 表1 符號、含義與單位 符號 含義 單位 A 承載物料的橫截面積 m2 A1 承載物料的上部的橫截面積 m2(mm2)a A2 當θ=0°時承載物料的截面積(承載物料的下部的橫截面積)(3輥托輥組) 外側輥子上倒梯形部分橫截面積(5輥托輥組) m2(mm2)a A3 內側輥子上倒梯形部分橫截面積(5輥托輥組) m2(mm2)a AN 設計輸送量下對應的承載物料的橫截面積 m2 AGr 工作面清掃器和輸送帶之間的有效接觸面積 mm2 AGr1 非工作面清掃器和輸送帶之間的有效接觸面積 mm2 B 帶寬 mm C 附加阻力系數 — D 滾筒直徑 mm D1 按輸送帶使用壽命條件確定的滾筒基準直徑 mm ELB 輸送帶縱向彈性模量 N/mm F 輸送帶的張力或阻力 N Fa 非穩態運行條件下由加速/減速度產生的慣性力 N FbA 加料段輸送物料的慣性阻力和(或)輸送物料與輸送帶間摩擦阻力 N Fd 凸、凹弧曲線段起始點的輸送帶張力 N Fc2 凸、凹弧曲線段終止點的輸送帶張力 N FD 滾筒上平均輸送帶張力 N FE 根據測試結果得出的單位長度壓陷滾動阻力 N/m Ff 加料段輸送物料與導料槽側板間的摩擦阻力 N FH 主要阻力 N Fg1 加料段外輸送物料與導料槽側板間的摩擦阻力 N FHs 逆止力 N FI 輸送帶繞經滾筒的彎曲阻力 N Fr 工作面清掃器的摩擦阻力 N Fr1 非工作面清掃器的摩擦阻力 N FN 附加阻力 N Fp 卸料器的摩擦阻力 N FR 根據測試結果得出的單位長度托輥轉動阻力 N/m FS 特種阻力 N Fshn 緩沖床(滑動床)的摩擦阻力 N FSk 加料段導料槽裙板密封的摩擦阻力 N FSk1 加料段外導料槽裙板密封的摩擦阻力 N FAp 拉緊滾筒的拉緊力 N FAt 輸送物料的提升阻力(在區段阻力計算中包括輸送帶的提升阻力) N Ft 滾筒軸承阻力 N FT 輸送帶特征點處張力 N FT1 輸送帶與滾筒相遇點的張力 N FT2 輸送帶與滾筒分離點的張力 N FTm 輸送帶的平均張力 N FTr 滾筒圓周驅動力 N FU 運行阻力(等于滾筒圓周驅動力) N FV 作用在滾筒上輸送帶的張力和滾筒旋轉部分重力的矢量和(數值) N Fw 凸、凹弧曲線段的附加彎曲阻力 N Ft 前傾阻力 N ΔFTm 輸送帶的平均張力FTm與最小輸送帶張力FTmin之差 N Im,N 設計質量輸送量 kg/s Im,th 理論質量輸送量 kg/s IV,N 設計體積輸送量 m3/s IV,th 理論體積輸送量 m3/s J 滾筒的轉動慣量 kg·m2 JD 驅動單元的轉動部件在減速器高速軸上的轉動慣量 kg·m2 Jf 飛輪的轉動慣量 kg·m2 L 輸送機的長度 m Ka 刮板系數 N/m PA 穩定運行條件下克服運行阻力所需的傳動滾筒的總功率 kW PM 驅動電動機總功率 kW PM,N 驅動電動機額定功率 kW Q 設計輸送量 t/h Ra 豎向凹弧段的曲率半徑 m(mm)a Re 豎向凸弧段的曲率半徑 m(mm)a S 相對于輸送帶名義拉斷強度的安全系數 — S0 考慮接頭工藝條件下的輸送帶的安全系數 — S1 考慮輸送帶預期壽命和工作應力的安全系數 — Smin 相對于輸送帶最小名義拉斷強度的最小安全系數 — a 加速度或減速度 m/s2 b 輸送帶有效寬度(理論承載物料的輸送帶寬度) m(mm)a b1 物料堆積在輸送帶上的寬度 mm b2 3輥托輥組上的物料寬度 mm bS 位于側輥上的輸送帶寬度(僅對于2輥和3輥托輥組) mm bSch 導料槽間的凈寬 m c0 確定最小滾筒直徑的計算系數 — cK 基于輸送帶邊緣張力確定的最小接頭疲勞強度的系數 — cR 將托輥轉動質量等效到托輥周邊上等效質量的計算系數 — cRank 主動側壓力系數 — cS 模擬摩擦系數的速度修正系數 — CSchb 加料段內由于物料擾動引起的附加阻力的系數 — cT 模擬摩擦系數的溫度修正系數 — cTd 確定槽形過渡最小長度基準值的系數 — cε 前傾阻力的計算系數 — d0 滾筒軸承的內徑 mm dB 輸送帶抗拉元件(芯層)的厚度(不包括輸送帶的上、下覆蓋層的厚度) mm dR 托輥直徑 m e 自然對數的底(e=2.718 28……) — eK 由輸送帶中性基準線到輸送帶邊緣的高差 mm eM 由輸送帶中性基準線到輸送帶中心的高差 mm fbase 模擬摩擦系數的基準值 — Δfs 與帶速相關的模擬摩擦系數的修正量 — ΔfT 與溫度相關的模擬摩擦系數的修正量 — f 模擬摩擦系數 — fi 用以計算上、下分支各區段的模擬摩擦系數 — fr 在一定帶速下托輥組輥子轉動的頻率 Hz fp 輸送帶的橫截面振動的近似固有頻率 Hz fRMBT 滾筒載荷系數(由輸送帶最大張力和名義拉斷強度確定) — g 重力加速度(g=9.81 m/s2) m/s2 h 高差(上運時h>0；下運時h<0) m hk0 輸送帶兩側邊緣構成的平面到槽形最低平面的距離 m hk1 輸送帶兩側邊緣構成的平面與滾筒上母線所在平面的距離 m hTr 槽形過渡段滾筒上母線平面與槽形最低平面的距離(滾筒抬高高度) m i 傳動比 — k 相對于輸送帶寬度的輸送帶張力(輸送帶張力在帶寬上的平均值) N/ram kK 輸送帶邊緣處單位寬度的張力 N/mm kM 輸送帶中心區域的單位寬度的張力 N/mm kN 輸送帶名義拉斷強度 N/mm kN,min 輸送帶最小名義拉斷強度 N/mm hrel 輸送帶的垂度(托輥組間輸送帶最大下垂量與托輥組間距之比) — kt 輸送帶接頭基準疲勞強度(考慮輸送帶接頭的強度降低的輸送帶拉斷強度) N/mm kt,rel 輸送帶接頭相對基準疲勞強度 — Δk 輸送帶邊緣和輸送帶中心區域單位帶寬上的張力的差值 N/mm l 區段的長度 m l2 中間2輥長度(5輥托輥組) mm lb 加料段導料槽的長度 m lK1 加料段外導料槽的長度 m lK 槽形過渡段輸送帶邊緣的長度 m lM 3輥托輥組的中間輥的長度 mm(m)a lR 托輥組間距 m ls1 外側托輥與物料的接觸長度 m lTd 槽形過渡段的長度 m lTd,eff 鋼絲繩芯輸送帶槽形過渡段的有效長度 m ΔlTd 過渡段的附加長度，鋼絲繩芯輸送帶的lTd,eff-lTd m lw 輸送帶翻轉段的長度 m mf 飛輪等效到滾筒周邊的等效質量 kg mD 滾筒、飛輪(如果設置)、驅動和制動裝置等效到滾筒周邊的等效質量 kg mL 帶式輸送機線路上的輸送帶、物料和托輥的等效質量 kg ∑m 帶式輸送機線路上的輸送帶、物料和托輥的等效質量與滾筒、驅動和制動裝置等效到滾筒周邊的等效質量之和 kg n 帶式輸送機劃分的區段數 — nR 帶式輸送機在穩定運行條件下允許的輥子最大轉速 r/min pA 與傳動滾筒相關的啟動系數 N/mm pA,0 與驅動相關的起動系數 N/mm pB 與制動滾筒相關的制動系數 N/mm pB,0 與制動相關的制動系數 N/mm pD 功率分配系數 N/mm pGr 工作面清掃器作用到輸送帶上的壓力 N/mm2 pGr1 非工作面清掃器作用到輸送帶上的壓力 N/mm2 pSk 輸送帶與密封之間的有效單位長度正壓力 N/m pBp 輸送帶的許用比壓 N/mm2 pBs 鋼絲繩芯輸送帶鋼絲繩下的許用比壓 N/mm2 q 主要阻力的估計系數 — qB 輸送帶的單位長度質量 kg/m qR 托輥旋轉部分的單位長度質量 kg/m qG,i 區段上物料的單位長度質量 kg/m s1 輸送帶厚度 mm sSp 拉緊滾筒行程 m v 帶速 m/s v0 給料到輸送帶上物料在輸送方向的速度 m/s sB 制動距離 m t1 輸送帶的鋼絲繩間距 mm tB 制動時間 s zD 傳動或制動滾筒的數量 個 zM 電動機(驅動單元)的數量 個 zR 區段上(上或下分支)托輥組的數量 組 zTr 滾筒的數量 個 zt 區段上(上或下分支)前傾托輥組的數量 組 α 圍包角 °或rad αc 凸、凹弧曲線段對應的圓心角 rad β 用于與物料計算物料橫截面積的物料動堆積角的等效堆積角 — θ 輸送物料的動堆積角(安息角) — δ 輸送傾角(上運時δ>0，下運時δ<0) — ε 側輥傾斜角(前傾角) — φ 有效填充系數 — φSt 傾斜輸送時理論總承載截面積的截面縮減系數 — φSt1 傾斜輸送時承載物料的上部的理論截面積的截面縮減系數 — λ 托輥組槽角、外側輥的槽角(4、5輥托輥組) — λ1 中間2輥的槽角(4、5輥托輥組) — μ 輸送帶與滾筒間的摩擦系數 — μ1 輸送帶與輸送物料間的摩擦系數 — μ2 輸送物料與導料槽側板間的摩擦系數 — μ3 輸送帶與托輥間的摩擦系數 — μ4 輸送帶與清掃器間的摩擦系數 — μ5 輸送帶與密封橡膠間的滑動摩擦系數 — μ6 緩沖床與輸送帶間的摩擦系數 — ρ 輸送物料的堆積密度 kg/m3 ΔεK 相對于輸送帶自然軸向凹弧段或凸弧段上輸送帶邊緣的附加伸長率(正或負) — ΔεK∞ 很長的曲線段輸送帶邊緣的ΔεK的極限值 — ΔεM 相對于輸送帶自然軸向凹弧段或凸弧段上輸送帶中心區域的附加伸長率(正或負) — ΔεM∞ 很長的曲線段輸送帶中心區域的ΔεM的極限值 — Δε∞ 很長的曲線段輸送帶中心區域與輸送帶邊緣之間的伸長率的差 — η1 電動工況電動機軸與滾筒軸之間全部傳動環節的總效率 — η2 發電工況電動機軸與滾筒軸之間全部傳動環節的總效率 — a 有些計算式中采用括弧內的單位。 5體積輸送量和質量輸送量 5.1 物料理論橫截面積 帶式輸送機的理論體積輸送量和質量輸送量是由所輸送物料在輸送帶上堆積形成的物料理論橫截面積和運行速度所決定的。物料的橫截面積則取決于輸送物料的動堆積角、托輥組的具體結構型式及裝料方式。 本標準在計算理論體積輸送量和質量輸送量時，假設所輸送物料橫截面的上表面的輪廓線為拋物線。圖1為常見槽形3輥托輥組支承輸送帶上的物料橫截面。 圖1 3輥托輥組水平輸送承載物料的理論橫截面 承載物料的理論橫截面積由承載托輥組的中間輥子長度lM、槽角λ、輸送帶有效寬度b及動堆積角θ確定。有效寬度b是在輸送帶寬度上留有一定的空邊距以避免輸送帶撒料的寬度，見式(1)、式(2)： b=0.9B-50(當B≤2 000) (1) b=B-250(當B>2 000) (2) 式中： B——帶寬，單位為毫米(mm)； b——輸送帶有效寬度(理論承載物料的輸送帶寬度)，單位為毫米(mm)。 水平轉彎運行的帶式輸送機由于輥子的傾斜布置可能會減小輸送帶的有效寬度。 水平布置的帶式輸送機的3輥托輥組支承輸送帶承載物料采用動堆積角θ計算的理論截面積Ath，可用截面積A1,th與A2,th之和來確定(見圖1)，見式(3)、式(4)、式(5)： (3) (4) Ath=A1,th+A2,th (5) 式中： Ath——承載物料的理論橫截面積，單位為平方米(m2)； A1,th——承載物料的上部的理論橫截面積，單位為平方米(m2)； A2,th——當θ=0°時的承載物料理論橫截面積(承載物料的下部的截面積)，單位為平方米(m2)； lM——3輥托輥組的中間輥的長度，單位為米(m)； θ——物料的動堆積角，單位為度(°)； λ——托輥組槽角，單位為度(°)； b——輸送帶有效寬度(理論承載物料的輸送帶寬度)，單位為米(m)。 當采用等效堆積角β計算橫截面積A1,th時，見式(6)： (6) 其中，β=θ/1.5。 物料的動堆積角取決于所輸送的物料的特性和帶式輸送機的長度、帶速等因素。在缺乏動堆積角經驗值情況下，可選擇： ——對于正常流動性物料，取0≤θ≤20°； ——對于流動性較高的物料，則取20°≤θ≤30°。 2輥托輥組承載物料的理論截面積：將lM=0代入式(3)和式(4)進行計算； 1輥托輥組承載物料的理論截面積：將lM=0，λ=0代入式(3)和式(4)進行計算。 1輥、2輥、4輥、5輥托輥組承載物料的理論橫截面積Ath的計算參見附錄A。 根據承載物料的理論橫截面積，理論體積輸送量，見式(7)： IV,th=Ath·v (7) 理論質量輸送量，見式(8)： Im,th=ρAth·v (8) 式中： IV,th——理論體積輸送量，單位為立方米每秒(m3/s)； Im,th——理論質量輸送量，單位為千克每秒(kg/s)； v——帶速，單位為米每秒(m/s)； ρ——輸送物料的堆積密度，單位為千克每立方米(kg/m3)。 5.2傾斜輸送的橫截面縮減系數 當帶式輸送機給料均勻、且水平、直線運行時，帶式輸送機的理論物料截面可以充分利用。 傾斜輸送時，受到物料重力、內摩擦角等因素的影響，圖1中的上部面積A1,th將縮減。當帶式輸送機對中良好并均勻給料、輸送粒度小的物料；且帶式輸送機線路上的最大傾角δmax≤θ時，上部面積的縮減系數，見式(9)： (9) 式中： φSt1——傾斜輸送時承載物料的上部的理論截面積A1,th的截面縮減系數，無量綱； δmax——帶式輸送機線路上的最大傾角，單位為度(°)； θ——同式(3)。 傾斜輸送的承載物料的理論截面積縮減系數φSt，見式(10)： (10) 式中： φSt——傾斜輸送時承載物料的理論截面積Ath的截面縮減系數，無量綱。 在應用式(9)、式(10)時，應注意傾斜輸送時的傾角最大只能等于動堆積角θ。此時只有截面積A2,th用于輸送物料。 5.3 設計輸送量和有效填充系數 當給定物料的設計質量輸送量Im,N時，設計體積輸送量IV,N，見式(11)： (11) 式中： Im,N——設計質量輸送量，單位為千克每秒(kg/s)； IV,N——設計體積輸送量，單位為立方米每秒(m3/s)。 所需要的截面積，見式(12)： (12) 式中： AN——在設計輸送量下需要的承載物料橫截面積，單位為平方米(m2)。 帶式輸送機的有效填充系數，見式(13)： (13) 式中： φ——帶式輸送機的有效填充系數，無量綱。 有效填充系數φ取決于： ——輸送物料的特性； ——粒度及其組成； ——動堆積角θ； ——帶式輸送機的運行條件； ——給料均勻性； ——輸送機的線路布置； ——輸送傾角； ——輸送能力的儲備。 有效填充系數φ用以評價理論物料截面積Ath與設計輸送量下所需截面積匹配性。在本標準中，一些計算參數是在有效填充系數為0.7<φ<1.1范圍內進行選擇，否則，應對所選計算參數進行修正，并且在某些情況下將超出上述的范圍，具體數值將依據試驗數據和工程師的經驗。 設計輸送量下的物料單位長度質量，見式(14)： 或qG=φρAth (14) 式中： qG——設計輸送量下輸送帶上物料的單位長度質量，單位為千克每米(kg/m)。 設計輸送量計算見式(15)： (15) 式中： Q——設計輸送量，單位為噸每小時(t/h)。 6 穩定運行條件的運行阻力和功率消耗 6.1 計算原則 運行阻力的計算通常是首先估計所用參數(如輸送帶和托輥的單位長度質量、模擬摩擦系數等)數值的基準值。這些數值應在計算過程中根據實際選擇確認或修正。通常應進行反復計算，以達到完全符合具體應用的計算結果。 在穩定運行條件時產生的運行阻力FU是由摩擦力、重力和其他阻力產生的總阻力。帶式輸送機傳動滾筒所需要的功率PA是由上、下分支產生的運行阻力總和與運行速度v的乘積得出，見式(16)： (16) 式中： PA——穩定運行條件抵抗運行阻力所需的傳動滾筒圓周上的總功率，單位為千瓦(kW)； FU——上、下分支運行阻力的總和，單位為牛頓(N)。 為了計算運行阻力，將帶式輸送機運行阻力劃分為： ——主要阻力FH(見6.2)； ——附加阻力FN(見6.3)； ——提升阻力FSt(見6.4)； ——特種阻力FS(見6.5)。 運行阻力之和FU等于從傳動滾筒傳遞到輸送帶上的滾筒圓周驅動力FTr，見式(17)： (17) 式中： FTr——滾筒圓周驅動力的總和，單位為牛頓(N)； FU,o,i、FU,u,i——分別為上、下分支、區段i上運行阻力，單位為牛頓(N)； no、nu——分別為上、下分支劃分的區段數。 阻力應以分段形式確定。分段的原則是在每個區段上具有相同的計算參數，例如：帶式輸送機的上分支、下分支，區段上的傾角δi、模擬摩擦系數，fi和單位長度物料的質量qG,i，以及托輥旋轉部分的單位長度質量qR,i?？紤]到方便計算機編程計算，在阻力計算中，可以采用從帶式輸送機的尾部到頭部進行編號，腳標i為區段的序號，腳標o表示上分支、u表示下分支(見圖2)，將滾筒作為單獨的區段編號。在后面的描述中，為了表達統一，將滾筒編號用腳標j表示，腳標T1為相遇點、T2為分離點。(見圖5和圖6)。 6.2主要阻力 6.2.1 主要阻力的計算 主要阻力發生在所有的帶式輸送機的輸送線路的整個長度上。它包括：托輥旋轉阻力、輸送帶壓陷滾動阻力、輸送帶彎曲阻力和物料內摩擦阻力等。主要阻力應在各個區段上分別計算。 為了簡化區段阻力的計算，按照阻力與運動載荷為線性關系來分別計算上、下分支每個區段主要阻力FH,i，見式(18)： FH,i=lifig[qR,i+(qB+qG,i)cosδi] (18) 式中： FH,i——區段i上的主要阻力，單位為牛頓(N)； li——區段i的長度，單位為米(m)； fi——區段i上的模擬摩擦系數，無量綱； qR,i——區段i上托輥旋轉部分的單位長度質量，單位為千克每米(kg/m)； qB——輸送帶的單位長度質量，單位為千克每米(kg/m)； qG,i——區段i上物料的單位長度質量，單位為千克每米(kg/m)； δi——區段i的輸送傾角，單位為度(°)； g——重力加速度，單位為米每二次方秒(m/s2)。 在確定輸送帶張力時，必需確定上、下分支區段主要阻力FH,o,i、FH,u,i(見8.3)。 帶式輸送機的主要阻力是上、下分支主要阻力FH,o、FH,u之和，見式(19)： (19) 式中： FH——總的上、下分支主要阻力，單位為牛頓(N)； FH,o,i、FH,u,i——分別為上、下分支區段i上主要阻力，單位為牛頓(N)； FH,o、FH,u——分別為上、下分支主要阻力的和，單位為牛頓(N)。 頭部 上分支運行方向 尾部 說明： 0、1、2——輸送機線路特征點； lo,1、lo,2、lu,1、lu2——分別為上分支、下分支區段1，2的長度； FU,o,1、FU,o,2、FU,o,2、FU,o,2——分別為上分支、下分支區段1，2上運行阻力。 圖2 區段劃分和穩定工況下的各段運行阻力 計算各區段主要阻力時，物料的有效填充系數應在0.7<φ<1.1的范圍內。否則，應對本標準所給出的計算參數的基準值進行修正。 在帶式輸送機線路中含有上運和下運區段時，應在極端載荷條件(給料不均勻、部分載荷和空載)下計算主要阻力，因為在這種情況下的阻力之和可能大大超過穩定運行條件下的阻力。 6.2.2模擬摩擦系數的確定 選擇模擬摩擦系數fi比主要阻力的計算更為重要，因為它決定了主要阻力。特別是對于提升阻力較小的帶式輸送機尤為重要。表2中給出的模擬摩擦系數廠i值可以用作上、下分支主要阻力計算。 如沒有測量值或經驗值，或僅有粗略的設備參數，可根據表2中運行條件和結構特性選取模擬摩擦系數廠的基準值。這些基準值是通過對上、下分支大量的測量及下列限制條件總結得出的： ——上分支為3輥固定式托輥組； ——輥子采用滾動軸承和迷宮式密封； ——輸送帶垂度hrc1≤0.01； ——有效填充系數為0.7<φ<1.1。 在實際設計中，為保證有較高的安全性，對于驅動裝置為發電運轉方式，采用較小的模擬摩擦系數f；對于驅動裝置為電動運轉方式，采用較大的模擬摩擦系數f。 如果計算精確度要求不高，可以采用此模擬摩擦系數f，按式(18)計算主要阻力。 表2模擬摩擦系數f的基準值(有效填充系數為0.7<φ<1.1) 特征 特征程度 輸送物料的內摩擦 中等 低 高 帶式輸送機的對中性 中等 好 差 輸送帶張力 中等 高 低 運行條件(粉塵，黏性) 中等 好 差 托輥直徑/mm 108～159 >159 <108 上分支托輥組間距/m 1.0～1.5 <1.0 >1.5 下分支托輥組間距/m 2.5～3.5 <2.5 >3.5 帶速/(m/s) 4～6 <4 >6 槽角/(°) 25～35 <25 >35 環境溫度/℃ 15～25 >25 <15 模擬摩擦系數f 基準值≈0.020 導致 模擬摩擦系數f減小至 模擬摩擦系數f增大至 0.010 0.040 6.2.3考慮溫度和帶速的模擬摩擦系數的修正方法 當考慮溫度和帶速的影響對模擬摩擦系數進行修正時，首先用表3確定模擬摩擦系數fbase的基準值。 不同帶建下的模擬摩擦系數的修正量，見式(20)： ΔfS=0.02·(cS-1) (20) 式中： ΔfS——與帶速相關的模擬摩擦系數的修正量，無量綱； cS——由表4給出的模擬摩擦系數的速度修正系數，無量綱。 不同工作溫度下的模擬摩擦系數的修正量，見式(21)： ΔfT=0.02·(cT-1) (21) 式中： ΔfT——與溫度相關的模擬摩擦系數的修正量，元量綱； cT——由表5給出的模擬摩擦系數的溫度修正系數，無量綱。 表3模擬摩擦系數fbase的基準值 安裝情況 工作條件 模擬摩擦系數fbase 水平、向上輸送及向下輸送的電動工況，帶速5 m/s 良好的工作條件，托輥轉動靈活，輸送物料的內摩擦較小，良好的安裝與維護 0.017 正常的安裝，通常的物料 0.02 不好的工作條件，低溫，物料的內摩擦高，物料超載，維護差 0.023～0.030 下運發電工況，帶速5 m/s 制造、安裝正常，電動機為發電運行條件 0.012～0.016 表4速度修正系數cS 帶速v/(m/s) 2 3 4 5 6 系數cS 0.80 0.85 0.90 1.00 1.10 表5溫度修正系數cT 溫度/℃ +20 0 -10 -20 -30 系數cT 1.00 1.07 1.17 1.28 1.47 修正的模擬摩擦系數，見式(22)： f=fbase+ΔfS+ΔfT (22) 式中： fbase——模擬摩擦系數的基準值，無量綱。 應用式(21)修正的模擬摩擦系數是偏于保守的。精確的模擬摩擦系數取決于實際所采用的輸送帶的類型和輸送機的結構設計。當帶速或溫度不是表4或表5中的數值時，可以通過插值法計算修正量。 6.2.4通過托輥轉動阻力和壓陷滾動阻力測量確定主要阻力的方法 為了在保證帶式輸送機性能的同時最小化設備和運營成本，應精確確定模擬摩擦系數f值。模擬摩擦系數fi主要是由托輥轉動阻力和輸送帶的壓陷滾動阻力確定。當輸送帶垂度相對較大時，輸送物料的擠壓阻力也會占較大比例。當測得托輥轉動阻力和壓陷滾動阻力時，可用下面的方法估算主要阻力。 在有效填充系數為0.7≤φ≤1.1情況下，承載區段(一般情況下是上分支區段)輸送帶的壓陷滾動阻力和托輥轉動阻力之和的正常值在主要阻力中占50％～85％，平均值為70％。空載區段(一般情況下是下分支區段)約為主要阻力的90％。