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8 ZERO POINT RETURN CONTROL
8.2.2 Machine zero point return method
The method by which the machine zero point is established (method for judging the
zero point position and machine zero point return completion) is designated in the
machine zero point return according to the configuration and application of the
positioning method.
The following table shows the six methods that can be used for this zero point return
method.
(The zero point return method is one of the items set in the zero point return
parameters. It is set in "
Pr.45 Zero point return method" of the basic parameters for
zero point returns.)
Pr.45 Zero point return
method
Operation details
Near-point dog method
When near-point dog turns from OFF
ON, deceleration is started.
(Speed decreases to "
Pr.49
Creep speed".)
After near-point dog has turned from ON
OFF, a stop is made at the first zero
point signal*, and the machine zero point return is regarded as completed at
completion of deviation counter clear output.
Stopper stop method 1)
The stopper position is defined as the zero point.
After deceleration is started when near-point dog turns from OFF
ON, the
machine is brought into contact with the stopper at "
Pr.49
Creep speed" to a stop.
After "
Pr.51
Zero point return dwell time" has then elapsed, the machine zero
point return is regarded as completed at completion of deviation counter clear
output.
Stopper stop method 2)
The stopper position is defined as the zero point.
After deceleration is started when near-point dog turns from OFF
ON, the
machine is brought into contact with the stopper at "
Pr.49
Creep speed" to a stop.
After the zero point signal* is then detected, the machine zero point return is
regarded as completed at completion of deviation counter clear output.
Stopper stop method 3)
The stopper position is defined as the zero point.
The machine starts at "
Pr.49
Creep speed" from the beginning, and is brought
into contact with the stopper at "
Pr.49
Creep speed" to a stop.
After the zero point signal* is then detected, the machine zero point return is
regarded as completed at completion of deviation counter clear output.
Count method 1)
When near-point dog turns from OFF
ON, the machine starts deceleration and
moves at "
Pr.49
Creep speed".
After the machine has moved the distance set in "
Pr.52
Setting for the
movement amount after near-point dog ON" from the position where near-point
dog turned from OFF
ON, it stops at the first zero point signal*, and the
machine zero point return is regarded as completed at completion of deviation
counter clear output.
Count method 2)
When near-point dog turns from OFF
ON, the machine starts deceleration and
moves at "
Pr.49
Creep speed".
The machine stops after moving the distance set in "
Pr.52
Setting for the
movement amount after near-point dog ON" from the position where near-point
dog turned from OFF
ON, and the machine zero point return is regarded as
completed.
*: The zero point input signals of the D75P2 in each zero point return method are described below.
Near-point dog method and count method 1): One-pulse signal output per each motor revolution
(Z-phase signal output from drive unit, etc.)
Stopper stop method 2), 3): Signal output upon detection of contact with stopper
(Supplied from an external device)
REMARK
Creep speed
The stopping accuracy is poor when the machine suddenly stops from high
speeds. To improve the machine's stopping accuracy, its must change over to a
low speed before stopping. This speed is set in the "
Pr.49 Creep speed".