DIN 22101 PDF
DOWNLOAD PDF. Report this file. Description. Download DIN - - Belt Conveyors Free in pdf format. Sponsored Ads. Shop Related Products. DOWNLOAD PDF. Report this file. Description. Download DIN - - Belt Conveyors Free in pdf format. Sponsored Ads. Account Login . DIN Continuous conveyors - Belt conveyors for loose bulk materials - Basis for calculation and dimensioning. Title (German). Stetigförderer - Gurtförderer.
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DIN BELT CONVEYORS by diego_mercado_ Download as PDF, TXT or read online from Scribd Englische bersetzung von DIN DIN - Download as PDF File .pdf), Text File .txt) or read online. DIN ‐08 with the explicit permission of the DIN Deutsches Institut für Normung e.V., Price group 17 Sales No. Berlin. Sole sale rights of German .
Continuous conveyors Belt conveyors for loose bulk materials Basis for calculation and dimensioning, English translation of DIN Licensed to Lee Becker. Single user license only. Copying and networking prohibited. Normative references Terms and definitions
This means: The force FTr,A shall be suitably selected to ensure friction grip between the material conveyed and the conveyor belt for the corresponding start-up acceleration a A.
It follows for fine grained bulk material: The start-up factor pA,0 related to the nominal torque of all drive motors shall be applied for the determination of the start-up factor pA in accordance with the equation below, where there are relatively small mass inertia torques of the rotating components of drives operating as motors in the steady operating condition, i.
For the dimensioning of the braking equipment the following is to be considered:. The required braking force FTr,B or the braking factor pB shall be determined for the most unfavourable braking conditions governed by the filling ratio and by the distribution of the load in downhill and uphill stretches of the installation with the relevant total motion resistance FW.
In this connection, either the braking distance sB or braking time tB is to be specified. This will determine the braking deceleration a B , which shall be such that the friction grip between the material conveyed and the belt is maintained.
In the case of fine-grained bulk material, the following applies: The braking factor pB0 related to the nominal torque of all drive motors shall be applied for the determination of the braking factor pB in the case of relatively small mass inertia torques of the rotating components of drives operating as motors in the steady operating condition, i. It may be necessary to limit the total braking force to a given value FTr,B,max, and consequently the braking deceleration to a limiting value a B,max, in order to reduce the belt stresses and those on other parts of the installation as much as possible, and in order to maintain the friction grip on the braked pulleys see 8.
As regards the design and dimensioning of holding devices, the maximum gradient resistance FSt,max likely to arise under the maximum permissible loading conditions and most unfavourable load distribution, shall be used as the base value, minus the primary resistance arising under these conditions. For safety reasons, only the minimum primary resistance anticipated shall be used in calculations. If a number of mechanical holding devices are used, the loads shall be suitably distributed.
Belt tensions should be kept to the lowest possible value in view of the stressing and layout of the belt and of other parts of the installation. The operation of belt conveyor installations requires minimum belt tensions in order to enable the transmission of forces to the belt by friction grip on the drive pulleys, to limit the belt sag and to enable the belt to be guided correctly.
The transmission of the maximum pulley peripheral forces which arise during starting, braking, or in the steady operating condition by friction grip on the individual driven or braked pulleys requires certain minimum belt tensions at the point where the belt runs onto and off the pulley. In the case of more than one driven or braking pulley, whether or not the friction grip is ensured in accordance with Equations 48 and 49 is to be verified for each individual pulley and for all operating conditions.
In this connection it shall be borne in mind that the total pulley peripheral forces FTr, FTr,A or FTr,B are distributed onto the individual pulleys in proportion to the torques induced in said pulleys by the driving or braking equipment. Table 6 gives preferred friction coefficients for the friction between belts with rubber covers and pulley surfaces of different finishes to be used in the design of belt conveyors for the steady operating condition.
Table 6 Recommended friction coefficients for the friction between belts with a rubber cover and pulley surfaces of different finishes see  for the design of belt conveyor installations for the steady operating condition. Friction coefficients for pulley surfaces of bright metal surface plain steel pulley. For the purpose of technical optimization of the belt conveyor installation, especially as regards energy efficiency, the calculated maximum relative belt sag hrel related to the distance between carrying idler centres shall be limited to values lower than 0,01 in the steady operating condition.
A greater belt sag is permitted in the non-steady operating condition. The greater the conveying speed and the lumpier the material conveyed, the smaller the sag should be. Greater conveying speeds require either considerably lower sag values or the acceptance of higher primary resistances see 6.
The following minimum belt tensions are required for a given maximum belt sag and a given distance between carrying idler centres: Upper strand with load: If a maximum value of hrel is specified, different distances between carrying idler centres can be allocated to the belt tension occurring along the path of an installation.
When these distances between centres are finally selected, the load-carrying capacity of the carrying idlers and the transverse vibration behaviour of the belt shall be taken into account see . In order to ensure the trouble-free operation of belt conveyor installations, it may be necessary to maintain higher minimum belt tensions in addition to the belt sag, especially for:. From the point of view of the correct sizing of the belt and of other parts of the installation, sufficient knowledge of the course or pattern of the belt tension along the length of the installation, and in particular the magnitude of the extreme values of the force, is extremely important.
Local belt tensions FT,i can be determined by summation of the motion resistances FW, i see Clause 6 and superimposition of the take-up force see 8. The calculation of motion resistances Fw,i for the individual sections of a belt conveyor installation in the stationary operating condition is given in Clause 6. During the starting and stopping process, the magnitude and pattern of the forces generated by the driving and braking equipment, and the breakaway resistance and motion resistances of a belt conveyor installation result in additional dynamic belt tensions.
These additional tensions are a function of the following factors, if we assume a belt acceleration independent of local conditions and, hence, quasi steady operating conditions of the conveyor see also Annex A:. For the frequently occurring case where the secondary resistance represents only a small proportion of the total resistance, the forces Fa,i resulting from acceleration or deceleration can be determined as follows for an individual section i with the aid of the belt acceleration a: Value cR,i depends on the design of the carrying idler.
Such devices shall enable the compensation of elastic, plastic, and thermal length variations of the belt, and additional lengths originating from the installation process and reserve lengths.
The calculation of the take-up distance provided below takes into consideration only the portion due to elastic elongation of the conveyor belt. The magnitude of the take-up forces will depend on the type and location of the take-up device, and on the operating conditions of the belt conveyor. In view of the costs and time needed for construction and design, take-up devices are preferably installed in those positions where the minimum belt tensions in the steady operating condition are anticipated.
Other aspects to be taken into consideration include:. In principle, a distinction is made between take-up devices with a fixed take-up pulley and take-up devices with a flying take-up pulley. In cases which deviate from the above, one must additionally take into consideration the difference between. This will result in the belt being operated with greater belt tensions than those required according to 8.
However, in the case of take-up devices with a flying take up pulley see also Annex A the take-up force will either remain constant under all operating conditions e. In both cases, suitably altered take-up pulley paths s Sp elongation: In general the belt tensions in the steady and in the non-steady operating conditions of a belt conveyor installation are decisive for the design and layout of:.
The maximum local belt tension, which is to be taken into consideration for the dimensioning of the conveyor belt, is determined taking into consideration all loading and operating conditions. For the purpose of determining the local belt tensions in non-steady operating conditions, the minimum belt tensions in accordance with 8.
Of the local minimum belt tensions at start-up FT,min,A and at braking FT,min,B in general it is FT,min,A which is decisive for the calculation of the take-up forces and the force FT,min in the steady operating condition. The belt tensions in the steady operating condition are determined by the required local minimum belt tensions in accordance with 8. However, there is, as a general rule, a greater minimum FT,min, dependent on the mimima FT,A,min or FT,B,min which occur during the non-steady conditions, and dependent also on the type of take-up device uses.
This consequently results in higher belt tensions than those required under the steady operating condition in accordance with 8. The thus established maximum belt tension FT,max is, as a general rule, the determining one for the calculation of the conveyor belt. However, in the case of unfavourable transitions or curves, even local belt tensions smaller than FT,max may cause the highest stress across the belt cross section see Clause 9.
Almost all conveyor belts are designed as troughed belts in order to enable larger cross section fills. For this purpose, the belts are reshaped from a flat belt into a troughed belt or vice versa transition zone. In the transition zones, the belt edges will travel a longer distance than the central zone of the conveyor belt.
Consequently, the calculated belt tensions are non-uniformly distributed across the cross section of the belt; and the edges are to bear a higher portion of the belt tensions than the central zone of the conveyor belt.
The same effect also occurs where troughed belt conveyors are routed through convex, vertical curves. If troughed belts are routed through concave, vertical curves, the central zone of the belt will be subject to higher tensions, whereas the belt tensions arising at the edges will be lower. In horizontal curves, one side of the belt will be subject to higher tensions than the other one. The geometry of the transition zone shall be suitably designed for the given belt tensions at the respective spots so as to avoid impermissible high stress and to prevent compression across the entire cross section of the conveyor belt.
The belt tensions are dependent on the geometry of the curve radius or transition zone transition length, trough angle, position of pulley surface relative to the deepest level of the trough. Therefore, the geometrical considerations are of vital importance with regard to the design and layout of the conveyor belt. The stresses in the conveyor belt are also dependent on its elastic characteristics and the belt tensions arising in the relevant positions.
Once the initial calculations required for the design and layout of the conveyor belt have been carried out, the geometry of the transitions and curves of the belt conveyor and the characteristics of the conveyor belt can be modified for further optimization see Clause If there are no particular requirements, the standard value of minimum transition length for 2-roller and 3-roller carrying idler sets shall be determined as follows: If the pulley is arranged at a higher position, shorter transition lengths are possible, resulting in a reduction of the belt tensions at the belt edge.
If the belt pulley is positioned at a lower position longer transitions will be necessary or result in higher belt tensions at the edges and lower tensions in the central zone of the belt. Figure 7 Transition length without pulley elevation above and with pulley elevation below With the tension difference k between the belt edge and the central zone of the belt according to Figure 8, the width-related belt tension is calculated as follows: Central zone of the belt:.
The length of the belt edge lK is the decisive parameter for the magnitude of the occurring belt tensions see Figure 7. Key a uniform distribution along the conveyor path outside the transition zones b non-uniform distribution in the transition zone c idealized distribution according to the approach in accordance with Equations 63 and 65 Figure 8 Distribution of belt tensions across the belt width in transition zones 9.
Forced length variations of textile conveyor belts are almost completely compensated for in the transition zone. Therefore, the determination of the elongations and tensions occurring is simpler than for steel cord belts. Provided the belt runs in the middle of the trough, the difference k of the width-related belt tension at the belt edge and in the central zone of the belt can be calculated for 2-roller and 3-roller carrying idler sets with the aid of the equation below see : In contrast to the characteristics of textile conveyor belts, with steel cord belts forced length variations will be compensated not only in the zone in which they occur, but also along considerably long portions of the adjacent belt.
Due to the relatively small elastic elongation of the steel cords of steel cord conveyor belts, the transition zones and convex curves have particularly serious effects on the stresses caused in the conveyor belt and other parts of the belt conveyor installation. Therefore, it is necessary to calculate the stresses as precisely as possible.
The stresses occurring with steel cord conveyor belts can be calculated very precisely thanks to the results of pertinent research work see  and .
The stress calculation method for steel cord conveyor belts is not only based on the geometry of the transition zone and the modulus of elasticity, but also on the belt design and modulus of shear of the rubber between the steel cords. This calculation is complex and therefore requires electronic data processing. The rough calculation below can be applied to 2-roller and 3-roller troughed idler sets. The following conditions are assumed for this purpose:.
The selected length of the transition zone is not shorter than the standard value determined in accordance with Equation In the calculation of the elongation of the conveyor belt, the elongation of the edge shall not be related to the transition length l but to the length l,eff:. This, however, is based on the condition that there is at least a section of belt with a length l,eff l to compensate for length variations before or behind the next pulley.
This condition is not fulfilled when there is a convex curve directly adjacent to the transition zone. In this case l,eff shall be approximated as l, i. In analogy with Equation 68 , the difference k of the width-related belt tension k between the belt edge and central belt zone is calculated as follows:.
Subclause In the horizontal plane, changes of direction can only be accommodated to a limited extent, and they require a quite extensive calculation see . In the case of convex belt guidance see Figure 9 of troughed belts, additional elongations at the edge of the belt and compressions of the belt centre will occur.
These superimpose themselves on the elongations caused by the belt tension in the form of positive and negative elongations, K and M. In the case of concave belt guidance see Figure 9 , however, additional elongation of the belt centre and compressions of the edge of the belt will occur. The absolute values of the resulting elongations are the same as elongations in a convex curve of the same radius, as long as the belt is not lifted from the conveyor idlers.
Figure 9 Conveyor installation with concave and convex transition curves In the case of short and medium curve lengths, the additional elongations resulting from convex and concave transition curves can only be calculated with a relatively high level of complexity see  ; however, as far as their magnitude is concerned they are always smaller than the limiting values K and M occurring in the middle zone of very long curves independently of the construction of the belt, and can be calculated with the aid of Table 7 and Figure 10 below.
Table 7 Definition of the limiting values K and M Limiting values. Figure 10 Aid to the calculation of the limiting values of elongation K and M at the centre of long convex and concave transition curves The distances eK and eM of the centre lines of the belt carcass from its neutral axis are illustrated in Figure The position of the neutral axis can be assumed in this case to pass through the centre of gravity of the belt carcass.
The following approximation equation can be used for the calculation of the difference of elongations between the belt edge and the belt centre for long transition curves and for 2-roller and 3-roller troughed idler sets, with bS calculated in accordance with Equation In design drawings the radius of vertical transition curves is frequently related to the upper edge of the centre idler.
This difference from the middle of the tension member to the upper edge of the centre idler can be neglected as insignificant compared to the curve radius. By introducing this value k in Equation 63 and Equation 65 , the width-related belt tensions in the central zone of the belt and at the belt edge can be calculated for textile and steel cord conveyor belts passing through the curve.
The additional elongation of steel cord belts can be determined with sufficient accuracy for small and medium curves as well by applying the method in accordance with . Usually no excessive stresses will occur in the conveyor belt in concave curves with small radii, as the belt will lift off the idlers see The tension members and cover layers of a conveyor belt shall be selected according to the operating conditions.
Their specification will be governed to a considerable extent by the characteristics of the bulk material conveyed physical and chemical characteristics, grain structure and by the application conditions of the belt environmental influences, scheduled service life, mechanical stresses, e.
The dynamic strength of the conveyor belt verified for vulcanized splices on a test stand according to DIN shall form the basis for the selection of conveyor belts and splices. The design and layout shall be based on the reference dynamic splice efficiency k t as defined in the above-mentioned test procedure see , ,  and . The values of the dynamic splice efficiency are established for splices made and tested under ideal conditions.
Deviations from these conditions, either related to the situation or due to the operating conditions, shall be taken into account by applying a safety factor S0, which shall be established in accordance with Table 8. Chemical and physical stresses, influences of natural ageing, and the frequency of high tensions and bending stresses are represented by factor S1 from Table 9.
At this stage, the design and layout shall be based on the highest belt tensions calculated for a belt cross section in the steady operating condition. High belt tensions, which may arise temporarily when conveyor belts with partial loads are passing through uphill and downhill stretches of the installation, shall be taken into account by carrying out a check in accordance with Equation Table 8 Determination of the safety factor S0 based on the classification of belt splice characteristics Characteristics of the belt splice.
Table 9 Safety factor S1 based on the classification of operating conditions Characteristics relevant to the dynamic strength of belt and belt splices. Hence the minimum dynamic splice efficiency k t,min of the belt and belt splice can be calculated as follows:. Figure The factor cK is chosen as 1,25 where the width related belt tension at the belt edge is calculated according to the method shown in 9. The relative dynamic splice efficiency k t,rel of a belt describes the portion of its nominal breaking strength k N:.
The relative dynamic splice efficiency is characteristic for a certain belt type and its splices. Therefore, it is to be incorporated in future product standards as a minimum requirement. Table 10 contains the relative values of dynamic splice efficiency for several belt types.
The following aspects shall be taken into consideration for their application:. The values for conveyor belts with textile plies are standard values based on practical experience.
It is likely that they will need to be corrected once a larger number of test results are available. The values for steel-cord conveyor belts have been determined in numerous tests and can be considered as minimum requirements which need to be verified. In the calculation of the minimum breaking force k N2 only the actual dynamic splice efficiency k t proven for a certain belt type and a certain type of splice may be applied. Table 10 Values for the relative dynamic splice efficiency k t,rel Belt type Textile belts with one ply Textile belts with two plies and thick intermediate layer Textile belts with more than two plies Textile belts with one ply Textile belts with two plies Steel cord belts Steel cord belts.
Please note that it cannot be expected that the standard values are achieved with aged or used belts. The minimum nominal breaking force kN,min is calculated as follows applying the highest value k K,max in accordance with Equation 75 and Equation 76 under the steady operating condition:. Taking the value k N,min calculated according to Equation 77 and the width-related mean belt force k at the point of the value k K,max calculated according to Equation 60 , the safety factor Smin related to the mean local belt force can be determined:.
In order to avoid extreme stresses in non-steady operating conditions and under those conditions that may arise when belts with a partial load are passing through uphill and downhill stretches of the conveyor installation, it shall be checked that the following limiting conditions are met: According to this method, the tension members of the conveyor belts are dimensioned exclusively on the basis of tensile loads.
It shall be checked whether they will provide sufficient resistance against additional stresses and whether their transversal rigidity will be sufficient for supporting the bulk material. They are therefore to be designed with a higher strength, if necessary. If DIN Standards and other normative regulations do not provide further details, the standard values for the minimum thickness of cover layers indicated in Table 11 and corresponding allowances for the carrying side of the belt as provided in Table 12 can be applied.
Certain minimum thickness values are required if a belt protection transverse reinforcement is incorporated in the conveyor layers.
In order to avoid impermissible cupping of the belt, the ratio of the thickness of the cover layer on the carrying side relative to the cover layer on the running side should not exceed 3: Table 11 Standard values for minimum thickness of cover layers on the carrying side and running side of the belt Material of longitudinal tension member. Table 12 Determination of the standard values for additions to the minimum thickness of carrying side cover layers in accordance with Table 11 Characteristics and their assessment Loading conditions Loading frequency Maximum particle size Bulk density Abrasiveness.
The idea behind the determination of minimum pulley diameters is directly linked with the expectations regarding the service life of the conveyor belt and its splices. The minimum pulley diameters to be determined in accordance with the method described in this clause allows the assumption that the endurance strength of splices will be at least equal to the expected service life of the conveyor belt, provided that the splices are properly executed.
Smaller pulley diameters than those determined in accordance with the method described in this document can lead to premature failure; they also facilitate wear and tear of pulley surfaces or lagging. The minimum pulley diameters of a belt conveyor installation will be determined by the design and layout, stresses and splicing method of the belt see also Annex A. A distinction is made between the following groups of pulleys when determining the minimum diameters:.
If DIN Standards and other normative regulations do not provide further relevant details, the minimum diameters of Group A pulleys, for the four different groups of pulley load factors provided in Table 14, can be determined as follows: The factor cTr is a parameter dependent on the material of the tension member according to Table 13 below:.
Table 13 Parameter cTr for the determination of the minimum pulley diameter Dtr Material of longitudinal tension member. Each diameter determined for Group A pulleys in accordance with the above description shall be rounded up to the next standard value indicated in Table The minimum diameters of Group B and C pulleys shall be chosen in relation to the pulley load factor from Table 14 that is relevant for Group A.
Table 14 Minimum diameter of Group A, B and C pulleys in relation to the utilization of the maximum pulley load factor in the steady operating condition Minimum diameter in mm without lagging DTr as per.
A 1 1 1 1 1 2 2 B 1 1 1 1 1 2 C 1 1 1 1 1 A 1 1 1 1 1 2 This clause deals with the calculation of suitable transitions and vertical curves suitable for a specified belt type. According to Equation 84 it follows that:. The transition lengths thus calculated provide sufficient accuracy for textile conveyor belts.
With Equation For the latter equation for steel cord belts, the parameter cK is to be considered as explained in the comments to Equation According to Equation 86 it follows that:.
A comparison of Equations 87 and 85 shows that the minimum troughing length for steel cord belts can only be calculated by iteration. Equation 86 and Equation 87 may be applied only if there is a piece of belt of sufficient length provided in front of or behind the belt pulley to compensate for length variations.
If there is a convex curve right after a transition, for example, the above condition is not met. In this case l,eff shall be replaced by l so that l,min can explicitly be determined using Equation For more precise calculations in which elongations resulting from superimposition are to be taken into consideration, it is recommended that the methods described in  and  be used. These elongations form the basis of the calculations below.
This lifting can be avoided if the following minimum radius is met under all operating conditions.
DIN - - Belt Conveyors
The length and type of the belt turnovers are dependent on the following parameters:. A distinction is made between the types of turnovers of the conveyor belt with different supporting principles as illustrated in Figure Key top: The standard values provided in Table 15 will be sufficient if the return strand is subjected to low belt tensions.
If this is not the case, a more precise calculation is to be carried out see . After a year validity, DIN The next version was published in with some formal and substantial shortcomings that required an early revision.
The working group responsible for revising DIN This task appeared to be unrealistic. In fact, the current descriptions are even more complex than those given in the edition because of new knowledge which needed to be incorporated.
The working group came to the conclusion that comprehensive computerized calculations, which are widely practiced, should be preferred in order to find improved technical and economical solutions. Nevertheless, simplified calculation methods are referred to wherever feasible i.
Re Clause 5 Theoretical cross section of fill Ath and equivalent angle of slope. In the case of a troughed belt, the bulk material cross section comprises the water cross section and the slope cross section lying above it.
Amongst other factors, the shape of the slope will depend on the properties of the bulk material conveyed e. The slope cross section which actually takes shape is markedly smaller than the cross section given by the static angle of slope. A calculation of this actual cross section can therefore in general only be undertaken under idealized assumptions.
In the case of belt conveyor installations with a horizontal layout, in German technical literature the slope cross section is nearly always idealized in the form of a triangular cross section, whilst in International Standard ISO The working group considered the adoption of the approach according to ISO and its incorporation in this revision, but finally refrained from this intention for the following reasons: ISO uses the angle of repose instead of referring to the surcharge angle as mentioned in ISO Hence it can be assumed that in its next revision, ISO will use an idealized triangular cross section.
Reduction factor st. In the case of inclined installations, to avoid determining cross sections of fill that are considerably too small when using this value, it will be necessary to calculate the factor st which is dependent on the inclination, with an angle of slope dyn close to the static angle of slope the angle of internal static friction.
If accurate values are required in borderline cases, such values are to be determined by tests carried out under conditions which approximate the actual application conditions as closely as possible.
For the calculation of resistances, even complex equations are not excluded here, since computerized calculations of this type are widely practiced. In deviation from DIN The simplest conceivable layout of a belt conveyor installation consists of two sections only: Simplifying a belt conveyor installation with uphill and downhill part sections as an installation with only two part sections may yield extremely false results.
In order to enable a high degree of accuracy of design and layout, the hypothetical friction coefficient f should be determined more precisely by measuring two major parts of the resistance to motion, i.
DIN 22101 - 2011 - Belt Conveyors
The indentation rolling resistance is generally measured with a single idler under consideration of the conveyor specific parameters. For the transformation to the indentation rolling resistance of a complete set of idlers, the values of the normal forces acting on each idler must be known. Figure A. Key 1 Bulk material 2 Direction of travel 3 Load over length on side idler 4 Load over length on centre idler 5 Related indentation rolling resistance on centre idler F'E,m 6 Related indentation rolling resistance on side idler F'E,s Figure A.
Here the values ca and cb vary depending on the measured function of the relevant indentation rolling resistance. The indentation rolling resistance FE,3 acting on each idler of a 3-roller idler set is determined by integrating the locally varying value of F'E along the contact line bR under consideration of the local line load. For the total indentation rolling resistance acting on the idler set the following numeric equation applies :.
In order to demonstrate the importance of the indentation rolling resistance for a safe dimensioning while at the same time minimizing investments and operating costs, Figure A.
Left column: Furthermore, the information shown in Figure A. Key Gradient resistances Special resistances Secondary resistances Flexing resistance of the belt Flexing resistance of the bulk material Idler running resistance Indentation rolling resistance.
For the secondary resistances a determination of each part is preferable to the determination of a generalized value for the portion of the primary resistance. In determining the friction resistance between conveyor belt and lateral chutes in the acceleration zone of a dyn. This factor characterizes the increase of the resistance due to additional pressure on the chute walls caused by the dynamic pressure of the material flow of feed material.
Consequently, the magnitude of the coefficient cSchb will be equal to 1 for the transfer height 0; it then increases with rising conveying speeds and dropping heights. A distinction has not been made between special resistances arising along the entire stretch of the installation and those occurring in individual sections only, as introduced by ISO The calculation approach detailed in this standard requires the calculation of resistance values for individual sections which implies the consideration of special resistances.
Detailed information on the magnitudes of the dynamic angle of slope dyn in the Rankine factor cRank applied in the calculation of the resistance arising at the material guide bars can be seen from the above comments on the reduction factor st. A belt conveyor installation for which the rate of increase of the pulley peripheral forces is limited during starting or stopping procedures, and where the belt is in motion along the entire installation, exhibits a belt acceleration which is independent of location; it behaves in a quasi steady-state fashion, and enables the dynamic additional forces to be determined as mass forces.
If the non-quasi steady operating conditions, e. For the calculations, a distinction is to be made between take-up devices with a fixed take-up pulley and those with a flying take-up pulley. Take-up devices with a fixed pulley are devices on which the position of the driven and non-driven pulleys remains unaltered for every operating condition of the conveyor.
The desired adjustment of the tensile force is effected, for example, by means of spindles screws or jacks.
Depending on the prevailing operating condition, a fixed take-pulley will result in varying forces at the tensioning location. Take-up devices with a flying take-up pulley are devices which generate tensile forces which are either independent of the operating conditions and practically constant, or which are suitably matched to the prevailing operating conditions.
This is achieved, for example with the aid of take-up weights, pneumatic or hydraulic devices and force-controlled jacks in the case of take-up pulleys with an adequate travel facility. Their mode of operation is, therefore, characterized by the fact that the total of the local belt elongations in the upper strand and the lower strand and consequently the take-up pulley travel vary:.
For the calculation of li a linear relationship between the elastic elongations and the belt tensions k related to the belt width is generally assumed as a simplification, and this is expressed by means of a mean widthrelated longitudinal modulus of elasticity related to the belt ELGk. Take-up forces that can be adjusted by suitable means shall be adjusted with an adequate speed in order to avoid sliding and slipping on the drive pulleys. In this context, it may be helpful to adjust the take-up force to a higher degree than the calculated one in order to ensure an adequate belt tension at any time.
Re Clause 9. The determination of belt tensions in accordance with DIN Non-uniform distribution of tensions over the width of a troughed belt as arising in transitions or curves was accounted for by a deduction r1 introduced for this particular purpose. This, however, no longer represents the state of the art in respect of the design and layout of conveyor belts with a high demand of accuracy. For the consideration and determination of additional elongations of the conveyor belt, a distinction shall be made between belts with textile plies and steel-cord belts because of their extremely different elastic characteristics.
Elongations of belt edges in the transition zones shall be calculated proceeding from the geometrical approach suggested by Laier see . Applying this approach, length variations and for conveyor belts with textile plies elongations and additional loads can be determined with sufficient accuracy. Length compensations of steel-cord belts involve considerably large belt portions adjacent to the transition zone, which is why higher belt tensions than those which actually arise will be calculated if the approach recommended for conveyor belts with textile plies is applied to steel-cord belts.
In the referenced literature see [12 and  descriptions of safe methods for the precise calculation of steel-cord conveyor belts are provided, which can be applied without problems using computerised support, provided that the mechanical characteristics of these belts are available.
If no mechanical characteristics of the belt are available, empirical relationships are provided for conveyor belts in accordance with DIN or DIN EN and steel-cord belts of similar design. These relationships will enable a sufficiently precise prediction of the stresses arising in conveyor belts installed on 2-roller idlers and the more frequently used 3-roller idlers, in many cases.
However, the relationships can only be referred to as being correct if the elastic characteristics of the belt currently ensured according to common practice, but not as specified in the applicable standards, are maintained, except for insignificant modifications.
The belt pulley should not be arranged at a level which is lower than the deepest trough level as this requires greater transition lengths or may aggravate the non-uniform distribution of belt tensions across the cross section of the belt. This also increases the load on idlers and bearings. There is also an increasing risk of damage to the belt as the belt may run into the gap between the rollers of the carrying idlers. Re Instead, one single limiting condition has been specified which will be applicable only to extremely high stresses in the non-steady operating conditions.
Safety factors are to be selected Table 8 of the previous edition of this standard in order to take the frequency of non-steady operating conditions into consideration. For this reason the deduction r2 is no longer required for the global consideration of these stresses. The load-bearing capacity of a conveyor belt is primarily dependent on the dynamic strength of the conveyor belt and belt splices.
DIN By testing the belt in accordance with DIN the dynamic splice efficiency of the conveyor belt and the belt splices can be 1. The characteristics of the belt splice manufacture are represented by the safety factors S0 provided in Table 8. The magnitude of stresses is expressed by the safety factor S1 to be selected from Table 9.
The values in Table 8 and 9 have been verified by comparison with the values obtained from existing and proven heavy-duty conveyor installations.
The relationship of the safety factors S0 and S1 to the safety factor Smin in steady operation which is based on the mean belt force over the width of the belt is given in Equation Its use leads to the results in Table A. From them the influence of belt specific parameters k t,rel, S0 and conveyor-specific parameters S1, k K,max on the safety factor Smin can be seen.
Table A. The safety factor S which is related to the nominal breaking strength of the belt k N, as opposed to the value kN,min can be determined analogously to Equation 78 as:. Because the relevant DIN Standards, International Standards and currently available drafts of European Standards do not contain data regarding the selection of the cover layer thickness, recommendations in this respect have been incorporated in this standard.
The cover layer thickness on the running side of the conveyor belt is determined to a great extent by the tension member, or in some cases by the transverse reinforcement, whilst the cover layer thickness on the carrying side of the belt is determined mainly by the stressing of the belt by the material conveyed, and consequently by the following influencing quantities: Nature of material conveyed:.
The thickness on the carrying side shall be at least equal to the thickness on the running side of the belt. The principle and general contents of the method of calculating minimum pulley diameters is identical with that described in ISO Therefore, a fourth category has been introduced for pulleys with loads exceeding the permissible values defined in DIN Re Clause This standard contains empirical values for minimum turnover lengths for different belt types and turnover principles.
Annex B informative Explanations of relationship of this standard to international standards The following ISO Standards have been taken into consideration for the revision of this standard: ISO In the ISO document, the cross section of fill of a troughed belt is composed of an equal sided trapezium or triangle surmounted by a segment of a parabola.
In this standard see Clause 5 , the upper portion of the cross section of fill is idealized in the form of an isosceles triangle, in accordance with the German technical literature. This approach has been maintained as it can be assumed that the standard ISO According to the recommendations contained in the ISO document for the calculation of the secondary and special resistances, the resistances due to the belt cleaners are deemed to be special resistances. However, as belt cleaners form part of the standard equipment of belt conveyor installations for bulk materials, the associated resistances have been allotted to the secondary resistances in this standard see 6.
Nevertheless, the standard refers to simplified calculation methods wherever feasible i. Replaces DIN OK, I agree. Standard DIN Please select from Subscription 1. Quick delivery via download or delivery service. All transactions are encrypted. Amendments Replaces DIN Relationship to other standards This document references:
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