(1) Calculate the formula symbol a———the angle of the idler groove, (°);
β———Conveyor inclination angle, (°);
γ———the bulk density of the material.t/m 3 ;
ε———The elastic elongation of the conveyor belt, %.
ε 1 ———the permanent elongation of the conveyor belt, %;
ε 2 ———The elongation of the edge of the conveyor belt is allowed, %, the belt core is 0.8%, and the steel cord is 0.2%;
ζ———the angle of inclination;
η 1 ———The efficiency of the reducer is generally η 1 =0.94;
η 2 ——— voltage drop coefficient, generally η 2 =0.9;
η 3 ———Safe coupling efficiency, η 3 =1.0 when not used, η 3 =0.96 when selecting;
η 4 ——— Take η 4 =0.9 for multi-motor drive, otherwise take η 4 =1.0;
θ, θ 1 , θ 2 ——— the wrap angle of the conveyor belt around the drive roller, rad;
λ———the ratio of the starting torque of the motor to the rated torque, see the motor sample;
μ, μ 1 , μ 2 ——— the coefficient of friction between the drive roller and the conveyor belt;
ξ———speed coefficient;
Ï———the dynamic angle of repose of the material (°);
Ï 0 ——— the static angle of repose of the material (°);
σ———the allowable strength of the conveyor belt, N/m;
σ 1 ———the allowable strength of each canvas of the conveyor belt N/(m · layer);
Ω—the drag coefficient of the roller;
A—the cross-sectional area of ​​the material on the conveyor belt, m 2 ;
A c ———cross-sectional area of ​​wire rope, m 2 /root;
A f ———starting factor, formula 33;
B——-bandwidth, m;
B c ———calculate bandwidth, m. Equation 4;
D c ———wire rope diameter, m;
D i ——— the diameter of the i-th roller in the various rollers having a wrap angle of more than 90°, m;
D p ——— drive drum diameter, m;
d m ———material size, mm;
E———wire rope elastic modulus, Pa;
E a ———Starting inertial force, N. Formula (31)
E b ———Brake inertia force, N;
E d ———bending stress, N. formula (51);
E—the bottom of the natural logarithm, r=2.71;
F ab ——— the maximum value of the starting effective tension F a or the braking effective sheet F b , N;
F a ———start effective tension, N. formula (41);
F b ——— brake effective tension, N. formula (41) and (42)
F c ——— the upper branch running tension, N. formula (18);
F k ———Additional resistance of the guide fence, N;
F p , K pi ———effective tension (traction), N. formulas (20) and (21);
—F p ———the absolute value of the effective tension, N.
F r ——— running tension of the lower branch, N. formula (19);
F s ——— additional resistance of the plow type unloader, N.
F sc ——— the upper branch allows the minimum tension, N. formula (24);
F sr --- the lower branch allows the minimum tension, N. formula (25);
F t ——— additional resistance of the unloading truck, N;
F 1 , F 11 ——— Initial calculation of tightness tension, N. Formulas (22), (26) to (30);
F 12 ———The second set of driving rollers is initially calculated for tight edge tension, N. Formula (28);
F 2 , F 21 ——— Initial calculation of loose edge tension, N. Formula (23), (26) to (30);
F 22 ———The second set of drive rollers is initially calculated for the loose side tension, N. Formula (28);
F 4 ——— total additional resistance, N, F 4 = (P k + P s + P t ) 1000 / V;
G———Package unit mass (weight), kg/piece;
[GD 2 ], [GD 2 ] j , [GD 2 ] ij ———Motor moment of inertia (flywheel torque), kg · m 2 .
g———gravitational acceleration, g=9.81m/s 2 ;
H———the vertical height of the conveyor, m. is negative when shipped;
[h]———Vertical height matrix, m. The element at the time of shipment is negative;
n i ———the height of the i-th segment in the vertical section of the conveyor, m. takes a negative value when it is shipped;
i——— dimensionless number;
j———— dimensionless number;
K———Power safety factor, when using a wound motor, DC motor or safety hydraulic coupling (coupling), take K=1.0, otherwise take K=1.10; [next]
K b ———rated cross-sectional coefficient;
K c ——— coefficient, see formula (33)
K l ——— length coefficient, see formula (7)
K s ———Conveyor belt safety factor, K s =12 for the four layers of the canvas core belt (18 for the heat-resistant type), and K s =7 for the steel cord core;
K st ———The minimum safety factor of steel cord conveyor belt, formula (51);
L———the horizontal length of the conveyor, m;
[L]——— conveyor horizontal length matrix, m;
L a ———2L t , the length of the geometric addition (conveyor belt), such as the increased length of the unloading car, multi-roller drive, etc., m;
L d ———Tighten the stroke, m. formula (47);
L Æ’ --- conveyor belt joint length margin, m.
L m ———When the conveyor is started, stopped or suddenly, the length of time required for the tensioning device to jump, m;
L 0 ——— conveyor correction length, m;
L t ———The belt conveyor is really long, m;
[l] --- conveyor horizontal length matrix, m;
l c ———The distance between the upper rollers, m. Generally taken, l c =1～1.2m;
l i ———the length of the i-th segment in the horizontal section of the conveyor, m;
l k ———The length of the guide fence, m;
l r ———The distance between the lower rollers, m. Generally take l r =3m;
l s ———step length or lap length, m;
M———Motor power, kW. Formulas (15) to (17)
M b ———Brake torque N · m.Formula (43)
[M l ]———Da's matrix;
M c ———number of ropes, roots;
m———quantity;
N—the quantity;
N, N j , N ij ——— motor revolution number, r/min;
N c ———Number of pieces of the transport package, piece /h. Formula (2);
P——-axis power, KW. formula (13);
—P————shaft power, absolute value, KW;
[P]———axis power matrix, KW. formula (14);
P———start additional power, KW. formula (17a)
P 1 ——— horizontal no load power, kW. formula (8);
P 2 ———Horizontal load power.kW.Formula (9);
P 3 ———vertical load power (bit energy), kW. formula (10);
P 4 ———Total additional power, kW;
P k ———Additional power of the guide fence, kW. Formula (11);
P s ——— additional power of the plough discharger, kW. formula (10);
P t ——— additional power of the unloading truck, kW;
Q———feed quantity (transport amount), t/h;
Q t ——— a rated delivery volume, t/h. See equations (1) and (3);
S i ———the tension of the tension point or the tension of the point i on the conveyor belt, N;
S max ———maximum tension of the conveyor belt, N;
S t ———Strength strength required for steel cord conveyor belt, N/m. Formula (50);
S 1 ... S 2m ———point-by-point tension on the conveyor belt, N;
T c — the spacing of the objects on the conveyor belt, m;
T g ———The allowable strength of the wire rope, N/root;
T s ——— canvas core conveyor strength, N / m. formula (48);
T u ———Tightening force, N. Equations (45) to (46);
T 1 ——— The final tightening tension, N. Equations (26) to (30);
T 2 ———The final calculation of the loose edge tension, N. Equations (26) to (30);
T 3 ——— The final set of the second set of driving drum tight side tension or reverse drum tension, N. formula (26) to (30);
T 4 ——— The final set of the second set of drive roller loose or reverse roller tension, N. Equations (26) to (30);
T i ———The tension at the tension point, N;
t a ———starting time, s, t a ≥ 5s or formula (34);
t b , t b i ———braking time, so equations (37) to (40);
υ, υ i ——— belt speed, m/s;
W———the moving part mass of the conveyor, kg/m. formula (5);
W c ———the quality of the upper roller group, kg;
W m ———The mass of the material on the conveyor belt, kg/m. Formula (6);
W q ———The quality of the material allowed to be poured by the downstream equipment, kg;
W r ———The quality of the lower roller, kg;
W t ———weight quality, kg;
W u ———the quality of the parts involved in the tensioning device, kg;
W 1 ———Conveyor belt quality (for calculation of power), kg/m;
W 2 ———Conveyor belt quality (actually selected), kg/m;
Z———the number of layers of the canvas core conveyor belt, layer;
Z c ———calculate the number of layers, layers;
Z max ———Maximum number of layers allowed, layer;
Z min ———Leverage the minimum number of layers, layers. [next]
(II) Design conditions Manufacturing plants in China and other countries have their own series of products. Therefore, in the design of the selection, the bandwidth, power, tension, tension, starting, braking, and selection of conveyor belts and other items can be calculated according to the conditions of the series and according to the user's requirements. Or supplemented by some non-series parts design. The raw data that is generally required is as follows:
(1) Material name and transportation volume. If the feed quantity has an uneven probability characteristic, its basic statistical characteristics or statistical data should be stated.
(2) Material properties. The material being conveyed is bulk or packaged. The maximum particle size and composition of the bulk material, loose density, static angle of repose and dynamic angle of repose; temperature, humidity, cohesiveness, wear and friction coefficient of the material. The external dimensions of the package.
(3) Installation features and working environment. Mark the conveyor line diagram with the main dimensions, including the projection length, solid length, lifting or lowering height, inclination, distance of each connected straight line segment and curve segment, height difference and other dimensions.
(4) Feeding and unloading methods.
(5) The working system of the conveyor.
(3) Belt conveyor allows the determination of the maximum inclination angle. The maximum inclination of the belt conveyor is related to the material and surface shape of the conveyor belt, the running speed of the conveyor belt, the nature of the material to be conveyed (grain size, shape, angle of repose).
(4) When designing belt conveyors with belt conveyors, a higher belt speed should be selected from the economical point of view. The maximum running speed of the belt conveyor is limited by its own specifications and component performance (such as rollers, seals, unloading devices, etc.); it is also related to the nature of the material being conveyed and the working environment.
(5) The loose density of the material and the loose density and angle of repose of the material of the angle of repose should be determined according to the experimental data.
(6) Calculation of transportation volume and conveyor belt bandwidth
A Calculation of the amount of package transport When transporting the package, the bandwidth should be 50 to 100 mm larger than the lateral dimension of the object. Object surface pressure on the conveyor belt, TD75 predetermined less than 5 kPa (0.05 kgf / cm 2) Number its delivery volume and delivery member Q i n c is calculated as follows:
D The bandwidth calculated by equation (4) must be checked against the maximum material size and its composition. [next]
(7) Calculation of driving power of belt conveyor
A-axis power calculation The calculation steps and methods of the belt conveyor power of the belt conveyor are as follows:
(1) Moving parts of belt conveyors, unit mass (weight) W:
(8) Plough unloader additional power P S :
P s =1.5BÏ… (12)
(9) Drive roller shaft power P:
P=P 1 +P 2 +P 3 +P k +P s +P t (13)
Checking the power of the B-axis The formula (14) only shows the calculation method of the shaft power of the simple belt conveyor under full load operation. Therefore, for the side shape is complicated (there are n turning points and n turning points, that is, the turning point of the tail end of the conveyor is O point, the turning point of the turning point appearing along the running direction of the conveyor belt, and the turning point of the head end roller is The n point, as shown in Figure 1f, at S 1 is 0, S 2 is 1 point, the following analogy) and the down belt conveyor, it is also necessary to carry out the power check and the shaft power check under no load condition, so that the belt conveyor The absolute value of the shaft power of the machine—P—is:
—P—≥MAX{—[P] —} (14)
The calculation method of [P] in the formula is:
The elements in each matrix are:
[P]=
[next]
(2) For P<0:
M=K—P—η 1 η 3 η 4 /η 2 (16)
D Motor power load start check When the shaft power P is large and zero and the low starting torque motor and elastic coupling are selected, the load should be checked to check the power of the motor.
(8) Calculation of the tension of the conveyor belt A Calculation of the running tension (running resistance) (1) Running tension of the upper branch (bearing branch):
The resistance F k +F s +F t of the guide fence and the unloading equipment is not included in the formula; when it is up (upper), H and h i take a positive value, and vice versa.
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