11-2
MHT260a (Engl.)
In designing the mechanical equipment system, the following shoud be examined as required.
(a) Reduction gear ratio
Use near the rated speed of motor is recommended where possible.
(b) Pre-load torque
When applying a pre-load to screw, load torque increases.
(c) Holding torque at vertical drive.
At stop of a vertical-feed load machine, energized-motor has a holding torque unless an external-braking device is used.
(d) Mechanical efficiency
(e) Rough estimated mechanical-coefficients
(i) Friction coefficient μ (ii) Mechanical efficiency η
Application μ Application η
Rail and iron wheel (crane traveling, traverse 0.05 Screw 0.5 to 0.8
motion, traveling carriage) Ball-screw 0.9
Linear way 0.05 to 0.2 Rack and pinion 0.8
Linear pole slide unit Spur gear reduction 0.8 to 0.95
Roller system Worm reduction gear At start 0.5 to 0.7
During operation 0.6 to 0.8
Belt drive 0.95
Chain drive 0.9
(iii) Densities of major materials ρ[kg/m
3
]
Steel 7850
Stainless steel 7910
Copper 8960
Aluminum 2700
Brass 8540
Poly-acetal 1430
(2) Model type selection determination
(a) Flow chart for selecting a model type
(*)
(＊) : Trms : Actual torque
Tr : Rated torque
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