Mitsubishi Electronics QD75D, QD75P Refer to the term Dwell Time Appendix, Motor torque MotorLoad

APPENDICES

STEP OUT

Stepping motors rotate in proportion to the No. of pulses (frequency), but the motor's rotation will deviate if the load is too large for the motor. This is called step out. If step out occurs, the motor must be replaced by one with a larger torque. Step out causes the positioning error to increase.

Motor torque

MotorLoad

STEPPING MOTOR

A motor that rotates a given angle (example: 0.15ø) when 1 pulse is generated.

For that reason, a rotation proportional to the No. of pulses can be obtained. 2-phase to 5- phase stepping motors are available. In the 3- phase type, the rotor rotates in order from A to C when a voltage is applied. Often found in compact motors, stepping motors rotate accurately without feedback. Be careful of step out when overloaded.

MELSEC-Q

STOP SIGNAL

In positioning control, this is the input signal that directly stops the operation from an external source.

The operation stops when the external stop signal (a-contact) turns ON (continuity).

STOP WITH STOPPER

This is one machine OPR method. With this method, a stopper is established at the OP, and the operation is stopped when the machine presses against it.

Motor burning would occur or the stopper would be damaged if the machine were left in that state. There are two methods to prevent this; a timer can be used to shut OFF the motor after a fixed time, or the motor can be stopped by limiting sudden increase in the motor torque when the machine presses against the stopper.

OP

Machine OPR

Stopper

C B

NA A S

B C

1)First, the A phase is excited by a pulse.

N

C

AA

C

S

2) When the B phase is then excited,

the force works in the direction shown by the arrows.

STROKE

The stroke is the variation in the operation by the distance from a stopped state to the next stopped state after a movement.

C B N

AA

B C

3) The nearest tooth to the

B phase is attracted, and the rotation stops.

C B

A A

B C

4)As the excitation phase is continuously changed, the rotor rotates in a clockwise direction.

STOP SETTLING TIME

Refer to the term "DWELL TIME".

Appendix - 89