Continuous Thrust - Mitsubishi Electric MELDAS MDS-B Series Instruction Manual

3-1-3 Continuous thrust

A typical operation pattern is assumed, and the motor's continuous effective load thrust (Frms) is
calculated from the load force. If numbers (1) to (8) in the following drawing were considered a one
cycle operation pattern, the continuous effective load thrust is obtained from the root mean square of
the thrust during each operation, as shown in the expression (3-2).
Motor
0
speed
Motor
0
thrust
F1
Frms =
Select a motor so that the continuous effective load thrust (Frms) is 80% or less of the motor rated
thrust (Fs).
Frms ≤ 0.8 × Fs
(1) Horizontal axis load thrust
When operations (1) to (8) are for a horizontal axis, calculate so that the following thrusts are
required in each period.
Period Load thrust calculation method
(Amount of acceleration thrust) + (Kinetic
(1)
friction force)
(2) (Kinetic friction force) + (Cutting force)
(Amount of deceleration thrust) +
(3)
(Kinetic friction force)
(4) (Static friction force)
− (Amount of acceleration thrust) −
(5)
(Kinetic friction force)
− (Kinetic friction force) − (Cutting force)
(6)
− (Amount of deceleration thrust) −
(7)
(Kinetic friction force)
− (Static friction force)
(8)
Chapter 3 Selection
(1) (2) (3)
F
1
F
2
F
3
t t t
1 2 3
Fig. 3-1 Continuous operation pattern
2 2 2
·t1 + F2 ·t2 + F3 ·t3 + F4
Table 3-1 Load thrusts of horizontal axes
(4) (5) (6) (7)
F
F
4
F
6
F
5
t t t t
4 5 6
t
0
2 2 2
·t4 + F5 ·t5 + F6 ·t6 + F7
t0
Normally the acceleration/deceleration time constant is
calculated so this thrust is 80% of the maximum thrust of
the motor.
The signs for the amount of acceleration thrust and
amount of deceleration thrust are reversed when the
absolute value is the same value.
Calculate so that the static friction force is always required
during a stop.
The signs are reversed with period (1) when the kinetic
friction does not change according to movement direction.
The signs are reversed with period (2) when the kinetic
friction does not change according to movement direction.
The signs are reversed with period (3) when the kinetic
friction does not change according to movement direction.
Calculate so that the static friction force is always required
during a stop.
3–4
(8)
7
Time
F
8
t
7 8
2 2
·t7 + F8 ·t8
Explanation
･･･
(3-2)
･･･
(3-3)