Figure 3-2 is the stroke control circuit of the power head. It is also controlled by the stroke switch to realize the reciprocating motion of the power head.
The control circuit completes a duty cycle: first, the power head I is moved from the position b to the position a to stop; then the power head II is moved from the position c to the position d to stop; then the power heads I and II are simultaneously returned to the original position. Stop [6].
The stroke switches ST1, ST2, ST3, and ST4 are attached to the bed b, a, c, and d, respectively. The motor M1 drives the power head I, and the motor M2 drives the power head II. The power heads I and II press ST1 and ST3, respectively, in situ. The working process of the line is as follows:
When the start button SB2 is pressed, the contactor KM1 is energized and self-locked, so that the motor M1 is rotated forward, and the power head I is advanced from the home position b to the point a.
When the power head reaches the a point position, the ST2 travel switch is depressed, and as a result, the KM1 is de-energized, the power head I is stopped; at the same time, the KM2 is energized, the motor M2 is rotated forward, and the power head II is from the in-situ c point to the d point. go ahead. There is a picture
When the power head II reaches the point d, the ST4 is depressed, and as a result, the KM2 is de-energized. At the same time, the KM3 and KM4 are energized and self-locking, and the motors M1 and M2 are reversed. Both the power heads I and II are retracted to the home position. When retracting to the home position, the stroke switches ST1 and ST3 are respectively depressed, and the KM3 and KM4 are de-energized, and both power heads are stopped in the home position.
The normally open contacts of the KM3 and KM4 contactors are self-locking, which ensures that the power heads I and II are indeed retracted to their original position. If only one contactor's contact is self-locking, the other power head may have lost the point to the in-situ contactor.