b Tension calculation when the effective tool F p <0 The following formula is applicable to the down Belt Conveyor. When F Ï <0 is calculated by taking ω=0.022, in order to obtain the brake running tension, take ω=0.012 to calculate F p .
(1) When F p <0, the head drive (this drive method is not ideal):
T 1 =F 1 =F 2 +—F p — =T 2 +—F p — (29b)
T 3 =T 4 =T 1 +F r (29c)
When T<F SC or F sr :
T 2 =F sc or F sr (29d)
T 1 =T 2 +—F p — (29e)
T 3 =T 4 =Tι+F r (29f)
Tension distribution, as shown in Figure 1d.
(2) When F p <0, the tail drive (single or double roller):
T 1 =F 1 =F 2 +—F p — =T 2 —F p — (30b)
T 3 =T 4 =T 2 -F r (30c)
When T 4 <F sr or F sr :
T 3 =T 4 -T sc or F sr (30d)
T 2 =T 3 +F r (30e)
T 1 =T 2 +—F p — (30f)
Tension distribution, as shown in Figure 1e. [next]
(9) Starting and braking calculation of the belt conveyor The size of the belt conveyor starting or braking force is directly related to the acceleration or deceleration of the conveyor belt. If the starting or braking is too fast, there will be belt surge, drive roller and conveyor belt slippage, motor overload, and damaged parts; for the down belt conveyor, rolling will also occur. Under normal circumstances, the acceleration and deceleration of the belt conveyor is 0.1 to 0.3 m / s 2 for starting acceleration or braking deceleration; the starting or braking time is generally 5 to 50 seconds for long distance or down belt conveyor. The starting or braking time of the machine is preferably greater than 10 seconds.
A Starting calculation (1) Starting inertia force:
The uplink can take A Æ’ =0.1~0.2; the long-distance parallel machine can take A Æ’ =0.35~0.5; in general, A Æ’ =0.35.
(4) Starting time:
If the above requirements are not met, increase the wrap angle of the drive roller; or increase the tension of the conveyor belt.
The above calculation formula [Equations (31) to (36)] is not applicable to the calculation when the starting tension of the down belt conveyor is negative (in this case, the starting calculation is not necessary). [next]
B Brake calculation a Determination of braking time (1) System balance method: first calculate the free stop time t bi of each belt conveyor, and then find the smallest one to determine the braking time of the system Æ’ b . However, For a belt conveyor operating under a downward power generation condition, it is impossible to freely stop at full load.
The above formulas are not suitable for the case where the upstream belt conveyor reverses the dumping after the full load is stopped. In this case, it is not necessary to calculate the braking time, because the selection of a general electromagnetic brake or a backstop can meet the requirements.
b inertia force calculation brake braking inertial force E b E b may refer to formula (31), as long as the formula E a to E b; T b can be changed.
c Calculation of brake effective tension F b (1) Belt speed from Ï… to zero: F b =E b -F p (41)
(2) When the upstream belt mechanism is reversed: F b = 2W m gH-F p (42)
When calculating F p , take ω=0.012.
d Calculation of braking torque When braking on a drive drum, the braking force on the shaft:
(10) Calculation of tension and tension stroke A Calculation of tension force T u =2T i (45)
When using a trolley or heavy hammer tensioner:
T a =(W t +W u )g (46)
B Calculation of the tension stroke L d =L t (ε+ε 1 )L m (47)
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