conveyor belts conveying systems 11 Dimensioning force-dependent take-up systems conveying systems 15 Calculation example for unit goods conveying MOVEMENT SYSTEMS Siegling - total belting solutions

This brochure contains advanced equations, figures and recommendations, based on our longstanding experience. Results calculated can however differ from our calculation program B_Rex (free to download from the Internet at www.forbo-siegling.com). These variations are due to the very different approaches taken: while B_Rex is based on empirical measurements and requires a detailed description of the machinery, the calculation methods shown here are based on general, simple physical equations, supplemented by certain factors that include a safety margin. In the majority of cases, the safety margin...

Unit goods conveying systems m = lT . Weight of conveyed goods per metre FU = µR . g . (m + mB + mR ) Direction conveyed upward: FU = µR . g (m + mB + mR ) + g . m . sin α Direction conveyed downward: FU = µR . g (m + mB + mR ) – g . m . sin α Direction conveyed upward: FU = µT . g ( m + mB ) + µR . g ( mB  + mR ) + g . m . sin α 2 2 Direction conveyed downward: FU = µT . g ( m + mB ) + µR . g ( mB + mR ) – g . m . sin α 2 2 Load examples to establish the

Lagged drum not recommended Minimum diameter of the drive drums dA

Checking the Transtex type selected if the value Jn_ is larger than C2, bo Note: If belts have been perforated, b0 must be reduced by the total width of the holes at a typical cross section. In the case of extreme temperatures, the C2 factors change. Please enquire. a stronger belt type (with a higher ki% value) must be used. C2 indicates the max. permitted belt pull per unit width for the belt type: The product data sheets list details on the relaxed k1% value. If example calculations and rough estimates without a data sheet are required, the following assumptions can be made (but not guaranteed):...

Unit goods conveying systems Take-up range for screwoperated take-up systems The following factors must be taken into account when establishing the take-up range: 1. The approximate magnitude of elon gation at fitting ε of the belt, resulting from the belt load. To establish ε, see pages 7 and 8. 2. The production tolerances (Tol) of the belt as regards the length. 3. Any external influences that might necessitate greater elongation (tensioning) than usual, or might require a safety margin Z, such as for example the impact of temperature, stop-and-go operation. Guidelines for shaft load at rest...

Guidelines for elongation at fitting ε for tail drives Tail drive in steady state forces The minimum elongation at fitting for return side drives is: Guidelines for elongation at fitting ε for return-side drives The minimum elongation at fitting for operating head drives is: Return side drive in steady state K for head drives K for return-side drives K for tail drives

Typical drive drum p = 180° Typical snub roller p = 60° Typical drive drum p * 180° Shaft load when tensioning belts Tension members made of synthetic materials display significant relaxation behaviour. As a result, the relaxed k1% value is taken as a basis for calculating belts in line with ISO 21181. It describes the probable long-term force-elongation properties of the belt material that has been subjected to stress due to deflection and load change. This produces the calculation force Fw. This implies that higher belt forces Fwinitiai will occur when tensioning the belt. They will have to...

Dimensioning force-dependent take-up systems Establishing FR In weight-loaded take-up systems, the tension weight must generate the minimum belt pull F2 to achieve perfect grip of the belt on the drive drum (spring, pneumatic and hydraulic takeup systems work on a similar principle). The tension weight must be able to move freely. The take-up system must be installed behind the drive section. Reverse operation is not possible. The take-up range depends on the effective pull, the tensile force F2 required, elongation of the belt ΔL, the production tolerance Tol, the safety margin for tensioning...

Goods conveyed Bulk density pS [103 kg/m3] Longitudinal angle of inclination 6 Guidelines for the longitudinal angle of inclination 5 permissible in various bulk goods. The machinery's actual angle of inclination a must be less than 5. These values depend on the particle shape, size and mechanical properties of the goods conveyed, regardless of any conveyor belt coating. The table shows the hourly volume flow (m3/h) at a belt velocity of v = 1 m/s. Conveyor belt lying flat and horizontal. The belt is equipped with 20 mm high longitudinal profiles T20 on the belt edges of the top face.

Under real world conditions, the theoretical values for volume flow are hardly ever reached as they only apply to horizontal belts with perfectly even loads. Uneven loads and the properties of the goods conveyed can decrease the amount by approx. 30 %. In inclined conveying, the theoretical quantity of goods conveyed is slightly less. It is calculated by applying the factor C6 which depends on the conveying angle a. Additional effective pull, for example from scrapers and cleaning devices, is taken into account by including the factor Q.

Bulk goods conveying systems Rolling resistance for support rollers f Establishing the mass of goods conveyed m Establishing the effective pull FU Support roller pitches f = 0.025 for roller bearings f = 0.050 for slide bearings Calculation as for unit goods The support roller pitch depends on the belt pull and the masses. The following equation is used to calculate it: If maximum sag of 1 % is permitted, (i.e. yB = 0.01 l0) Recommendation l0 max ≤ 2b0 lu = Support roller pitch on upper side in mm = Maximum conveyor belt sag in mm = Belt pull in the place concerned in N = Weight of goods conveyed...