Timing Belts - Cross & Morse - #29

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cop Cat ref_09.indd table.main {} tr.row {} td.cell {} div.block {} div.paragraph {} .font0 { font:6.00pt "Arial", sans-serif; } .font1 { font:7.00pt "Arial", sans-serif; } .font2 { font:8.00pt "Tahoma", sans-serif; } .font3 { font:10.00pt "Tahoma", sans-serif; } .font4 { font:9.00pt "Times New Roman", serif; } .font5 { font:11.00pt "Times New Roman", serif; } .font6 { font:12.00pt "Times New Roman", serif; } .font7 { font:25.00pt "Times New Roman", serif; } .font8 { font:6.00pt "Trebuchet MS", sans-serif; } Green Belt Sélection Procédure A Green Belt used for linear application can be selected either by considération of the loads and accelerative forces applied to the belt, or by the power applied to the driving pulley and the speed of rotation. In order to select the Green Belt it is first necessary to compile together, dependant on method of selection, the following relevant design parameters. For vertical drives Corrected value Fp = (M+ Mb + Mc) a + 9.807M + FF...N If significantly changed recheck belt width - section 6. The belt can then be specified by type - width x length e.g. U5M 2OE x 1500 - 1500mm length belt a) b) c) d) e) f) Is drive horizontal or vertical The mass of all moving parts to be moved by the belt. Maximum Belt velocity Maximum rate of acceleration Frictional forces due to load being moved Desired Pulley, diameters Pulley Centres/Total length of movement required Driving Motor Power Driving Pulley speed (r.p.m.) Any width constrictions Terms and Definitions :- a = A = b = d = do = dp F = FF = Fm = Fp Fs = FT = Fx = L = Lc = Lm = mB ■ M = MB Mc = acceleration centre distance pulley shafts belt width m/sec mm cm mm mm mm N N N N N/cm N N mm mm mm gm/m kg 53 0 j) bore of pulley outside diameter of pulley pitch diameter of pulley total force seen by belt friction forces seen by belt max. acceptable force for belt (table p23) linear driving force tooth shear resistance (see table below) total force seen by belt fitting tension for belt (see p25) length of belt length of moving carriage distance moved by carriage unit weight of belt ( table p23) weight of moving components (carriage) weight of belt length mB x L compensated weight for pulley Selection of Belt Considering Motor Power 1) Use Power and Pulley speed to select size (pitch) of belt from graph 1 opposite. 2) Considering the desired pulley diameter determine number of teeth in pulley No. Teeth Z = dp xll 3) From Tooth Shear Resistance table against Pulley Speed 'N' determine value for Fs for selected belt size. 4) Determine numbers of pulley teeth in mesh Zm, normally equals z/2, Zm has a maximum Value of 12 5) Then Belt Width b = P x 12 x 106 mm Fs x Zm x Z x N Select next larger standard width to width calculated 6) Belt length L = 2A + Zxp mm Where centre distance not specified but carriage motion distance is, the min. pulley centre can be determined as:- Amin = Lm + Lc + dp. mm The belt can then be specified by type - width x length e.g. U8M 50E X 2600 - 2600mm length belt. Selection of Belt considering loads and accelerative forces 1) Calculate the linear drive force Fp For Horizontal drives Fp = M x a + FF N For Vertical drives Fp = M (9.807+a)+ FF N From table below select size of belt for the application kg dj X = Mp d2 ""2"" V do2/ Mp= weight of idler pulley N = shaft speed p = belt pitch P = drive power V = belt/carriage linear speed Z = number of teeth on pulley Zm= number of teeth in mesh with belt Tooth Shear Resistance kg r.p.m mm KW m/sec = 12 max Pulley Speed N r.p.m Value for Teeth Shear Resistance Fs N/cm by belt size U5M U8M HPU8M UI4M 0 36.70 75.71 75.71 139.65 20 36.36 74.72 74.72 137.37 40 36.02 73.73 73.73 135.03 60 35.68 72.74 72.74 132.81 80 35.34 71.75 71.75 130.53 100 35.00 70.76 70.76 128.24 200 32.85 65.10 65.10 118.00 300 31.50 62.00 62.00 111.00 400 30.45 59.75 59.75 105.00 500 29.55 57.35 57.35 100.51 600 28.58 55.50 55.50 96.04 700 27.78 53.64 53.64 92.39 800 27.10 52.08 52.07 89.31 900 26.52 50.73 50.72 86.64 1000 26.00 49.54 49.54 84.28 1100 25.54 48.50 48.49 82.17 1200 25.13 47.56 47.54 80.25 1300 24.75 46.70 46.69 78.49 1400 24.40 45.92 45.90 76.86 1500 24.08 45.20 45.18 75.34 1600 23.78 44.53 44.51 73.90 1700 23.50 43.90 43.88 72.54 1800 23.24 43.31 43.29 71.25 2000 22.75 42.24 42.21 68.81 2200 22.31 41.27 41.24 66.54 2400 21.91 40.40 40.35 64.38 2600 21.54 39.58 39.53 62.30 2800 21.19 38.83 38.77 60.29 3000 20.86 38.12 38.05 58.32 3200 20.54 37.44 37.37 56.38 3400 20.24 36.80 36.72 54.46 3600 19.96 36.19 36.09 52.54 3800 19.68 35.62 35.50 50.62 4000 19.41 35.04 34.91 48.69 4500 18.76 33.68 33.52 43.81 5000 18.14 32.39 32.20 38.77 5500 17.53 31.15 30.92 33.53 6000 16.94 29.93 29.66 28.07 6500 16.34 28.74 28.41 22.34 7000 15.75 27.53 27.15 - 7500 15.15 26.33 25.89 - 8000 14.54 25.11 24.62 9000 13.28 22.62 22.00 10000 11.97 20.04 19.27 o 9 Size of Belt Drive Load Range N Max Rate acceleration m/sec2 U5M 0 - 920 80 U8M 500 - 3650 60 HPU8M 500 - 3800 60 U14M 1000 - 9000 40 m 3 œ CD 2) Considering the desired pulley diameter determine number of teeth in pulley No. Teeth Z = dp x H Determine Pulley speed, r.p.m. from linear speed of belt V. N = 60V x1000 r.p.m 0) Zxp © O 4) 5) 6) 7) 8) From Tooth Shear Resistance table against Pulley Speed 'N', determine value for Fs for selected belt size. Determine number of pulley teeth in mesh Zm, normally equals Z/2. Zm has a maximum value of 12. Then belt width b = Fp mm Fs x Zm Select next larger standard width to width calculated. Belt Length L = 2A + Zxp mm Where Centre distance not specified but carriage motion distance is, the min. pulley centre distance can be determined as:-A min. = Lm + Lc +dp mm Having determined a belt size and length the calculation for linear drive force can be recalculated incorporating the belt weight and idler pulley (the drive pulley inertia does not effect the belt forces, for horizontal drives.) Corrected value Fp = (M + Mb + Mc) a + FF... N o 03 03 3 o 0) 03 O O 3 27