5 Project Planning for Gear Units

Transcription

1 General information Project Planning for Gear Units.1 General information The planning information provided in this catalog is primarily concerned with the special needs of EBD gear units. For detailed planning information, please refer tochapters 4-6 in the SEW-EURODRIVE catalog "Industrial Gear Units of the MC.. Series" Edition 04/200, / EN..2 Efficiency of gear units The efficiency of the gear unit is mainly determined by the gearing and bearing friction. Note that the starting efficiency of a gear unit is always less than its efficiency at operating speed. The efficiency of MC.. helical and bevel-helical gear units varies depending on the number of gear stages. The efficiency is: MC2P: 0.97 MC3P: 0.9 MC2R: 0.97 MC3R: Service factor F S, peak factor F F Service factor F S The service factor takes into account the load impacts generated by the driving motor and the driven machine. Recommended values in respect to field of application driven machine operating period / day are given in the following table. These tables are valid for electric motors used as driving machine. For other types of driving machines, the following correction values apply: Combustion engines with four or more cylinders: F S (selection table) Combustion engines with one or three cylinders: F S (selection table) + 0. Field of application/industry Agitators and mixers Fans Driven machine Service factor operating period /day < 3 h 3-10 h > 10 h Agitators for liquids Agitators for liquids (variable density) Agitators for solids (non-uniform material) Agitators for solids (uniform material) Concrete mixers Dry cooling towers Wet cooling towers Catalog Mixer and Agitator Drives of the MC.. Series

2 Fstart Start factor Peak factor F F The peak factor F F takes into account how often peak loads occur. The permitted peak load depends on the frequency per hour and is calculated according to the following formula: 1. Based on torque M = K2 zul 2 x M N2 F F [ M K2 zul M N2 F F = permitted peak torque at the gear unit output = gear unit nominal torque = peak factor according to the following table Calculating the peak load M K2 max : * Start M K2 max = M a x F [Nm] M K2 max M a F start Maximum peak torque at the gear unit output Output torque based on the motor power Start factor * If F start is not specified, please observe the start factors according to section.4. Checking the gear unit selection: M K2 max M K2 zul Frequency of peak load per hour > 160 Peak factor F F The gear units may only be overloaded for a short period of time. Individual peak loads must not last for more than ten seconds..4 F start Start factor The start factor F start takes into account the overload generated by the starting procedure. Start mode Start factor - F start direct 3.0 soft starter 1.8 frequency inverter star / delta 1.3 fluid coupling without delay chamber 2.0 fluid coupling with single delay chamber 1.6 Catalog Mixer and Agitator Drives of the MC.. Series 31

3 Thermal rating PT. Thermal rating P T The thermal rating P T of a gear unit is the power that a gear unit can transmit continuously without exceeding a certain oil temperature. The thermal rating depends on the following factors: Type of lubricant used Ambient temperature Gear unit ratio Optional forced cooling methods (e.g. fan on HSS) Installation altitude of the gear unit ( table, altitude factor f 1 ) Lubrication method of the gear unit ( table, lubrication factor f L ) For the following ambient conditions, the thermal rating can be directly read from the selection tables for ambient temperatures of 20 C or 40 C, natural cooling, or for cooling with fan altitudes < 1000 m (f 1 = 1) bath lubrication (vertical positions) P T = P TH f 1 f 2 f L f T P TH = Nominal thermal rating of the gear unit. The values given in the selection tables in chapters depend on the ambient temperature and cooling method. For 20 C: P TH [20] 40 C: P TH [40] with cooling fan 20 C: P TH [20] 40 C: P TH [40] f 1 = f 2 = f L = f T = Altitude factor (see the next page) Mounting option factor 1.07 = shaft mounted with torque arm 1.00 = all other mounting options Lubrication factor 1.0 = splash and bath lubrication 1.1 = pressure lubrication Ambient temperature factor (see the next page) The selection tables already take account of different ambient temperatures; the factor is therefore only relevant for ambient temperatures above 40 C. For ambient temperatures of 30 C, the thermal rating can be interpolated P TH [30] = P TH [20] + P TH [40] 2 32 Catalog Mixer and Agitator Drives of the MC.. Series

4 Altitude factor f 1 Altitude H [m above sea level] ) f ) Intermediate values must be interpolated Consult SEW-EURODRIVE in case of deviating conditions. Ambient temperature factor f T Ambient temperature f T 1.0 1) 20 C 30 C 40 C 0 C 1), 2) 1.0 1) The selection tables in chapter already take account of different ambient conditions. 2) Interpolation between P TH[20] and P TH[40] in chapters is possible 1.0 1) Contact SEW- EURODRIVE.6 The permitted overhung load (axial and radial forces on the gear unit shafts) depends on different factors: Gear unit service factor Required bearing lifetime Direction of axial load (away from or towards gear unit) Direction of radial load (rotating or at a distinct position) Relation of axial to radial load For the input shaft, a guideline value is given in the selection tables in chapter 10 and 11 of the basic MC catalog "Industrial Gear Units of the MC..Series", publication number For the output shaft, the permitted overhung load can be checked with the help of diagrams. Two kinds of diagrams were developed for typical load cases: Catalog Mixer and Agitator Drives of the MC.. Series 33

5 Load case 1: Typical aerator drive Lh > h Fs > 2.0 X = 1000 n 2 < 7 min-1 X 9063AXX The tables apply to Minimum gear unit service factor of 2.0 Bearing lifetime for LSS of h Output speed n 2 = 7 min -1 The tables are still valid (on the safe side) for speeds < 7 min -1 The tables must not be used for speeds > 7 min -1 Foot-mounted gear units Point of application of radial load is X = 1000 mm from shaft shoulder The tables are still valid for application points < 1000 mm for application points > 1000 mm, the value for the radial load for use in the diagram can be interpolated using the following formula: F = ra X x 1000 mm F ra X = Radial load to use in the selection tables in N = Occurring radial load in N = Application point of radial load from shaft shoulder in mm Direction of radial load is at a fixed, most unfavorable point 34 Catalog Mixer and Agitator Drives of the MC.. Series

6 Load case 2: Typical agitator drive L h > h Fs > 1. X= L 2 n 2 < 100 min-1 [2] L [1] X= L 2 929AXX [1] Radial bearing (external to gear unit, customer supplied and part of agitator) [2] Gear unit The tables apply to Minimum gear unit service factor of 1. Bearing lifetime for LSS of h Output speed n 2 = 100 min -1 The tables are still valid (on the safe side) for speeds < 100 min -1 The tables must not be used for speeds > 100 min -1 For solid LSS, the application point of the radial load is in the middle of the LSS (=L/2) for application points < L/2 mm, the tables must not be used for application points > L/2 mm, the value for the radial load for use in the diagram can be interpolated using the following formula F = ra F x R 2 x X L F ra X L = Radial load to use in the selection tables in N = Occurring radial load in N = Application point of radial load from shaft shoulder in mm = Shaft length in mm Catalog Mixer and Agitator Drives of the MC.. Series 3

7 For hollow LSS, the application point of the radial load is at the lower end of the hollow shaft Direction of radial load is at a fixed, most unfavorable point Gear unit is foot mounted for bearing arrangement EZ22 Gear unit is flange mounted for bearing arrangement EF12 with solid or hollow shaft Solid and hollow shaft gear units are shown Example of how to read the diagram Required bearing lifetime of LSS: h Radial load: = F ra = 6 kn in X = 1000 mm distance from shaft shoulder Axial load: 2 kn towards gear unit X F F ax 914AXX 36 Catalog Mixer and Agitator Drives of the MC.. Series

8 Example for overhung load diagramm [3] torwards gear unit (pressure in LSS) [A] kn Fax [N] [2] [1] away from gear units (tension in LSS) [1] [2] [3] 6 kn Fra [N] [B] 9290AEN [A] Fax [N]: Applied axial load on the LSS in N Negative: away from gear unit (tension in LSS) Positive: towards gear unit (pressure in LSS) [B] Fra [N]: Applied radial load on the LSS in N [1] Standard bearing arrangement (no EBD!) = Standard [2] EBD with shaft 2 ("thick" solid shaft) = EN22/EZ22 [3] EBD with shaft 2 ("thin" solid shaft and hollow shaft) = EZ12 Result: Bearing arrangement EZ12 fulfills the requirements. (With a radial load of 6 kn and bearing arrangement EZ22/EN22, the permitted axial load towards the gear unit is approximately only 19 kn. EZ12 has a permitted axial load of 29 kn towards the gear unit) Catalog Mixer and Agitator Drives of the MC.. Series 37