Automatic Needle Threading Of Machine Head - ELNA E9020 Service Manual

5) The main shaft which has been disengaged stops at 40˚ to 50˚ by the main shaft disengaging stopper.
6) Main shaft returns from disengagement when the data other than the disengagement of main shaft occur (70˚), the needle throwing STM starts driving at 287˚ and
the main shaft disengaging link moves to the waiting position.
7) The main shaft disengaging cam slides by the main shaft disengaging cam spring and comes in contact with the main shaft hand wheel.
8) When the main shaft rotates by 30˚ to 70˚ in the normal direction in the state that the main shaft comes in contact with the main shaft disengaging cam, the main shaft
disengaging cam slides further by the main shaft disengaging stopper and the main shaft hand wheel is joined together with the main shaft. As a result, the rotation
power is connected.

Automatic needle threading of machine head

1) Automatic needle threading mechanism is actuated by the exclusive threading stepping motor and the lateral feed stepping motor.
2) The automatic needle threading is carried out by the following.
1 Thread transfer body section ........ transfers the needle thread from the waiting position located on the upper side of the sewing machine.
2 Needle eyelet threading section ... passes the needle thread which is drawn in front of the needle eyelet to the needle eyelet, and puts the thread on the needle
3 Threading section of thread take-up spring .... puts the needle thread which is drawn by the thread transfer body to the thread take-up lever and the the thread
3) The possible range of automatic needle threading is 36˚ to 54.5˚. When the needle threading key is pressed within this range, the automatic needle threading
mechanism starts working. A series of motions is as described below.
1 Interlocking with the rotation of the lateral feed stepping motor, the drawing roller and the auxiliary roller separate from each other.
At the same time, the drawing stepping motor is joined together with the threading body.
2 The thread transfer body comes down and rotates. (The threading STM starts rotating in the normal direction.)
3 The needle eyelet threading section comes down following the descending thread transfer body.
4 The thread transfer body stops in the state that the needle thread is drawn in front of the needle eyelet.
At this time, the needle threading hook stops descending at the position of needle eyelet as well.
5 The needle threading hook rotates and enters the needle eyelet. At the same time, the needle clamp thread hook arm catches the needle thread and pushes the
needle thread to near the entrance of the needle clamp thread guide.
6 By the rotation of the drawing STM, the threading body catches the needle thread and rotates. Then the threading body stops at the entrance of the thread take-
up spring. (The threading body detects the stop position by opening the needle thread breakage detection shield plate.) At this time, the needle thread is put to
the thread take-up lever and the drawing roller.
7 The threading STM starts rotating in the reverse direction. The thread transfer body rotates and goes up.
At the same time, a) the needle threading hook catches the needle thread and psasses it to the needle eyelet.
b) The needle clamp thread hook arm returns to its home position after leaving the needle thread in the needle clamp thread guide.
8 When the lateral feed stepping motor returns to its home position, interlocking of the threading body with the drawing stepping motor is released and the
threading body returns to its home position by means of the force of the spring. At this time, the needle thread is left in the the thread take-up spring.
9 The thread transfer body stops at the upper waiting position (origin) and the automatic needle threading completes.
clamp thread guide.
take-up spring.
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