上海维宏电子科技股份有限公司
Weihong Electronic Technology Co., Ltd.
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For instance, the selected screw lead of X-axis for a certain type of machine tool is 5mm, and the
stepping angle of stepping motor is 1.8 degree, with ―10‖ subdivision and motor directly connected with
screw by coupling. Thus, the pulse equivalent of X-axis is:
5mm
Pulse equivalent 0.0025mm/p
360
10 1
1.8
Servo Motor
In general, set the default value of pulse equivalent (p) as 0.001mm/p and calculate electronic gear
ratio (B/A). Their relationship can be shown as:
B encoder resolution
Electronic gear ratio mechanical deceleration ratio
screw pitch
A
pulse equivalent
Namely,
Electronic gear ratio (B/A): the parameter of servo driver (take YASKAWA driver as an example, B is
PN202 while A PN203). This ratio represents servo scales up or down the pulse frequency sent by CNC
system. When B is larger than A, it means scaling up and vice versa. For example, provided the pulse
frequency sent by CNC system is 100HZ, if the numerator of electronic gear ratio (B) is set as 1 while the
denominator 2, the actual running speed of servo is 50HZ. On the contrary, if the numerator is set as 2
while denominator 1, the actual running speed turns to 200HZ.
Encoder Resolution (F): needed pulse number for one circle of servo motor. Please see the servo
motor label plate and then refer to the corresponding manual to confirm its encoder resolution.
See Section 5.3 for more info of electronic gear ratio and encoder resolution.
Rotary Axis
The pulse equivalent of rotary axis refers to the rotation degree of the axis clamping the workpiece
corresponding to each pulse. The difference of rotary axis movement from linear axis movement lies in
that the screw pitch of rotary axis is 360 degrees. Therefore, in calculating rotary axis pulse equivalent,
you just need to replace screw pitch with 360.
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