Fagor 8035-T - Page 199

 Installation manual
CNC 8035
CONCEPTS
feedback system
5.
(SOFT M: V15.3X)
(S
OFT T: V16.3X)
·199·
5.4.2 Resolution
The CNC provides a number of machine parameters for the axes and for the spindle in order to
establish the counting resolution of each one of the axes and the spindle.
PITCH (P7)
Defines the pitch of the ballscrew or the linear encoder being used. When using a Fagor linear
encoder, this parameter must be set with the pitch value of the feedback signals (20 µm or 100 µm).
When using a rotary axis, indicate the number of degrees per encoder revolution. E.g. if the encoder
is mounted on the motor and the axis has a gear ratio of 1/10, parameter PITCH must be set with
the value of 360/10 = 36.
NPULSES (P8)
Indicates the number or pulses/rev provided by the rotary encoder. When using a linear encoder,
it must be set to ·0·. When using a gear reduction on the axis, the whole assembly must be taken
into account when defining the number of pulses per turn.
SINMAGNI (P10)
Indicates the multiplying factor (x1, x4, x20, etc.) that the CNC must apply only to sinusoidal
feedback signal.
For square feedback signals, this parameter must be set to 0 and the CNC will always apply a
multiplying factor of x4.
The counting resolution for each axis will be defined by means of the combination of these
parameters as shown in the following table:
Example 1:
Resolution in "mm" with squarewave encoder.
We would like to obtain a 2µm resolution by using a squarewave encoder mounted on 5 mm pitch
leadscrew.
Since the CNC applies a x4 multiplying factor to squarewave signals, we would require an encoder
that provides the following number of pulses (lines) per turn.
Nr of pulses = ballscrew pitch / (multiplying factor x Resolution)
Nr pulses = 5000 µm / (4 x 2 µm) = 625 pulses/turn
Therefore:
Allthough the CNC accepts a maximum squarewave frequency of 400 kHz, when using Fagor
squarewave rotary encoders their output frequency is limited to 200 kHz; thus, the maximum
possible feedrate (F) will be:
Max. feedrate = (200.000 pulses/sec. / 625 pulses/turn) x 0.2 inch/turn
Max. feedrate = 1600 mm/s = 96 m/min.
PITCH NPULSES SINMAGNI
Square signal encoder
Sinusoidal signal encoder
Leadscrew pitch
Leadscrew pitch
Nr of pulses
Nr of pulses
0
multiplying factor
Square signal linear encoder
Sinusoidal signal linear encoder
linear encoder pitch
linear encoder pitch
0
0
0
multiplying factor
INCHES = 0 PITCH=5.0000 NPULSES = 625 SINMAGNI=0