
B–65142E/04
4. SELECTING A MOTORDESCRIPTIONS FOR THE α series
45
Be sure to enter data in this row. Data entered here is needed for
determining the approximate motor load conditions (inertia, load torque).
Enter the movement directions of driven parts such as the table and tool
post (e.g. horizontal, vertical). Write their angle from the horizontal level
if their movement directions are slant (e.g. slant 60°).
Enter the weight of driven parts, such as table, tool post, etc. by the
maximum value including the weight of workpiece, jig, and so on. Do
not include the weight of the counter balance in the next item in this item.
Enter the weight of the counter balance in the vertical axis, if provided.
Enter whether the counter balance is made by a weight or force as this
influences inertia.
Enter the type of table slide (e.g. rolling, sliding or static pressure).
Enter a special slide way material like Turcite, if used. Also enter the
friction coefficient value. This item is significant in estimating the friction
coefficient for calculating mainly the load torque.
Enter the diameter, pitch, and axial length of the lead screw in order.
If a rack and pinion or other mechanism is used, also enter the traveling
distance of the machine tool per revolution of the pinion.
Enter the gear ratio between the ball screw and the servo motor, gear ratio
between the final stage pinion and the servo motor in case of the rack
pinion drive, or gear ratio between the table and the motor in case of rotary
table.
Enter basic data that is required for selecting the motor.
For details on how to calculate each of the items, see 4.1 to 4.2.
Pay special attention to the unit for calculating and expressing torque.
Enter the movement of the machine tool when the motor rotates one turn.
Example
D When the pitch of ball screw is 12 mm and the gear ratio is 2/3,
12 2/3 = 8 mm
D When the gear ratio is 1/72 in rotary table ;
360 1/72 = 5 deg
Enter the least input increment of NC command. (The standard value is
0.001 mm.)
Enter the rapid traverse rate required for machine tool specifications.
Enter the motor speed during rapid traverse.
Enter the rapid traverse rate required for machine tool specifications.
Enter a load inertia applied by the moving object reflected on the motor
shaft. Do not include the inertia of the motor proper in this value. For
details on this calculation, see 4.1.1.
In the case of a linear shaft, enter the load inertia calculated by logical
calculation if you enter the next item. In the case of a rotary shaft,
however, the load inertia cannot be calculated by logical calculation.
4.3.2
Data
Specifications of moving
object
D Axis movement direction
D weight of driven parts
D Counter balance
D Table support
D Feed screw
D Total gear ratio
Mechanical
specifications
D Movement per rotation of
motor
D Least input increment
CNC
D Rapid traverse rate
D Motor speed in rapid
traverse
D Cutting rapid traverse
D Motor shaft converted
load inertia