TIMING PULLEYS & BELTS T E C H N I C A L T E C H N I C A L T: +44 1246 455500 [email protected] www.ondrives.com Updated July 2020 subject to change for use as a guide only. Z e d o1 z B1 L B F zul t z 1 a d k1 n 1 d o2 z 2 d k2 n 2 F U1 v a = Centre distance (mm) M B = Acceleration torque (Nm) t B = Acceleration time (s) d = Bore (mm) r = Density (kg/dm 3 ) M = Torque (Nm) n = RPM (min -1 ) d k = Outside diameter (mm) P = Power (kW) J = Moment of Inertia (kgm 2 ) L B = Belt length (mm) i = Ratio F zul = Allowable tensile load (N) B = Pulley width (mm) t = Pitch (mm) v = Velocity (m/s) F U = Peripheral force (N) w = Angular velocity (s -1 ) d 0 = Pitch circle diameter (mm) z = No. of teeth when i = 1 z 1 = No. of teeth of small pulley z 2 = No. of teeth of large pulley z B = No. of teeth in the belt z e = No. of teeth in mesh Mass Moment of Inertia J = 98.2 · 10 -15 · B · r · (dk 4 – d 4 ) Acceleration Torque M B = J · ∆n 9.55 · t B Angular Velocity w = p · n 30 Rpm n = 19.1 · 10 3 · v d 0 Velocity v = d 0 · n 19.1 · 10 3 Pitch Circle Diameter d 0 = z · t p Peripheral Force F U = 2 · 10 3 · M d 0 F U = 19.1 · 10 6 · P n · d 0 F U = 10 3 · P v Torque M = d 0 · F U 2 · 10 3 M = 9.55 · 10 3 · P n M = d 0 · P 2 · v Power P = M · n 9.55 · 10 3 P = F U · d 0 · n 19.1 · 10 6 P = F U · v 10 3 Belt length i ≠ 1 L B ≈ † (z 2 + z 1 ) + 2 a + 1 (z 2 – z 1 )† 2 2 4 a p Belt length when i = 1 L B =2 a + p · d 0 L B =2 a + z · t [ ] Centre Distance (approx.) for i = 1 a ≈ z B · z 1 · t 2 Centre Distance (approx.) for i ≠ 1 a ≈ L B - (p /2)(d 01 + d 02 ) + L B - (p /2)(d 01 + d 02 ) 2 - (d 02 + d 01 ) 2 4 4 8 ( )
11
Embed
TMG PULLES & BELTS Pulleys and Bel… · (N/cm) M Spez (Ncm/cm) P Spez (W/cm) Rpm, n (min-1) F U Spez (N/cm) M Spez (Ncm/cm) P Spez (W/cm) TMG PULLES & BELTS TNAL T: +44 1246 455500
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
TIMING PULLEYS & BELTS
TE
CH
NIC
AL
TE
CH
NIC
AL
T: +44 1246 455500 [email protected] www.ondrives.comUpdated July 2020 subject to change for use as a guide only.
Z e do1
zB1 LB
Fzul
t
z1
a
d k1
n1
do2
z2
dk2
n2
FU1 v
a = Centre distance (mm)MB = Acceleration torque (Nm)tB = Acceleration time (s)d = Bore (mm)r = Density (kg/dm3)M = Torque (Nm)n = RPM (min-1)dk = Outside diameter (mm)
P = Power (kW)J = Moment of Inertia (kgm2)LB = Belt length (mm)i = RatioFzul = Allowable tensile load (N)B = Pulley width (mm)t = Pitch (mm)v = Velocity (m/s)
FU = Peripheral force (N)w = Angular velocity (s-1)d0 = Pitch circle diameter (mm)z = No. of teeth when i = 1z1 = No. of teeth of small pulleyz2 = No. of teeth of large pulleyzB = No. of teeth in the beltze = No. of teeth in mesh
Mass Moment of InertiaJ = 98.2 · 10-15 · B · r · (dk4 – d4)
Acceleration TorqueMB = J · ∆n 9.55 · tB
Angular Velocity
w = p · n
30
Rpm
n = 19.1 · 103 · v
d0
Velocity
v = d0 · n
19.1 · 103
Pitch Circle Diameter
d0 = z · t
p
Peripheral Force
FU = 2 · 103 · M d0
FU = 19.1 · 106 · P n · d0
FU = 103 · P v
TorqueM = d0 · FU
2 · 103
M = 9.55 · 103 · P nM = d0 · P 2 · v
PowerP = M · n 9.55 · 103
P = FU · d0 · n 19.1 · 106
P = FU · v 103
Belt length i ≠ 1
LB ≈ †
(z2 + z1) + 2 a + 1 (z2 – z1)† 2
2 4 a p
Belt length when i = 1
LB = 2 a + p · d0LB = 2 a + z · t[ ]
Centre Distance (approx.) for i = 1
a ≈ zB · z1 · t
2
Centre Distance (approx.) for i ≠ 1
a ≈ LB - (p/2)(d01 + d02) + LB - (p/2)(d01 + d02)
2 - (d02 + d01)2
4 4 8( )
TE
CH
NIC
AL
TE
CH
NIC
AL
Updated July 2020 subject to change for use as a guide only.
Pulley Tooth VersionsAll Ondrives pulleys are supplied with normal backlash tooth gap form.SE and zero backlash are available on request. Please contact our Technical department.
FlexibilityThe minimum number of teeth on the pulley / minimum diameter recommended for trouble free operation is based on the belt type selected. When considering drives with reverse bending (contraflexure), it is especially important to remember that the minimum number of teeth on the pulley / minimum diameter must be increased. Values are given at the end of each belt type section.
Pre-tensionThe pre-tension FV is determined by the maximum operating peripheral force FU. The purpose of pre-tension is to allow both sides of the belt between the pulleys to run without sagging. It is important to recognise the difference between the loaded (tight) and unloaded (slack) side of a drive as when power is applied, the tension increases in the loaded (tight) side and decreases proportionately in the slack side.The pre-tension is correctly set when the unloaded (slack) side of the belt always remains taut under the maximum operating loads. Any sag or flap indicates too low a pre-tension.
For two pulley drives: For multiple pulley and linear drives:Pre-tension ≥ 0.5 · Peripheral force Pre-tension ≥ 1.0 · Peripheral force FV ≥ 0.5 · FU FV ≥ 1.0 · FU
Tension Member Tensile Loading Fzul The timing belt is designed correctly when the tension member loading value is not exceeded.Values for each belt can be found on the product page. Fu < Fzul
Tooth Sheer Strength The belt width (in cm) required to transmit known peripheral force FU, torque M or power P without exceeding the maximum allowable tooth shear strength is calculated using any of the following formulae and the values from the tables:
FU 100 . M 1000 . P b = ze.FUspez b = z1.ze.Mspez b = z1.ze.Pspez
T: +44 1246 455500 [email protected] www.ondrives.comUpdated July 2020 subject to change for use as a guide only.
Synchronous Drive Belt Width bThe synchronous drive belt width b in mm results from the power P to be transmitted, corrected by the overall service factor co and the power rating PR corrected by the teeth in mesh factor c1 and the length factor c5. The following applies to standard belt width:P · co ≤ PR · c1 · c5 If P · co > PR · c1 · c5 The next larger standard width should be applied.To obtain a synchronous drive belt width as narrow as possible, the toothed pulleys should be selected as large as possible.This will result in a longer service life at a lower bending load.
Overall Service Factor co The overall service factor co takes into consideration safety factors for special operating conditions caused by loading conditions, acceleration and fatigue. It is calculated on the basis of the following factors: co = c2 + c3 + c4
An initial selection is made using the belt graphs based on P. co and speed of the small pulley. This is then checked against PR.c1.c2PR is taken from the Power Rating Tables. Where the graph offers two possible pitches a check should be made of both.
Number of Teeth in Mesh Factor c1Ze: 2 = 0.2, 3 = 0.4, 4 = 0.6, 5 = 0.8, ≥6 = 1.0
Fatigue Factor c4Daily Period of Operation: 10-16 hours = +0.2, Daily period of operation 16+ hours = +0.4, Additional Belt Deflection (e.g. by means of tensioning rolls): = +0.2, Intermittent operation = –0.2
Load Factor c2 The load factor considers the type ofprime mover (driver) and driven machine. Values are reference only.
HTD Timing Belts and Pulleys
Pre-tensionAfter an initial selection has been made our Technical department would be happy to advise on checking the belt tension and its correct setting.
Tension Member Tensile Loading FzulThe timing belt is designed correctly when the tension member loading value is not exceeded.Values for each belt can be found on the product page. Fu < Fzul
Electric Motors with slow starting torque (up to 1.5 times the rated torque). Water and steam turbines, internal combustion engines with 8 and more cylinders
Electric Motors with medium starting torque (1.5 to 2.5 times the rated torque). Internal combustion engines with 4-6 cylinders
Electric Motors with high starting torque and braking torque (more than 2.5 times the rated torque). Internal combustion engines up to 4 cylinders