26
Md. N. H. Nihad et al.
2 Materials and Methodology
This work mainly focuses on the continuous bottom thread supply where stitch
loop forms by using a half-circular rotation of “Rotary Hook/Loop Taker/Shuttle.”
The half rotations performed here by turning the middle bed shaft into a crankshaft
on the right side were facing the machine pulley. There joined a connecting rod
which is connected with a rack. The rack is being held inside a frame where it
gets a reciprocating motion from the circular motion of the crankshaft through the
connecting rod. As a result, the rack is proving a half-circular rotary motion to the
pinion (1) adjoined on a shaft that is connected with another gear (2) on the left
side and supported by a bush placed under the machine bed. The gear (2) is being
provided with the same half-circular motion from the pinion (1) directly (Fig. 1).
Gear (2) is meshing with an idle gear (3) which rotates on a shaft attached to a
bush with the bed. The idle gear (3) drives the spur gear (4) which is attached with
the loop taker. The Loop Taker gets the rotation and being hold by a cylindrical pipe
which is fastening to the body. This pipe is the ultimate bottom thread path where
one end used for thread insertion (5) and the other end exposed to the inside of the
Loop taker. The inside portion is divided into two sections; one is for loop rotation
and the other one for the bottom thread supply. The loop rotation part is modified
(Fig. 3) into a nearly half-circle shaped bracket in such a manner that the upper
thread can pass smoothly. The other section is made of another half-circle shaped
bracket with a tensioning device connected to the opening of that cylindrical pipe.
During the stitch operation, the loop taker gets the upper thread from the needle and
rotating half around and then releases it in the midway. But the upward movement
of the needle creates a tensile force that takes the loop up through the gap between
the two half-circular brackets. On that spot, the bottom thread passing through the
Fig. 1 The rack and pinion
Md. N. H. Nihad et al.
2 Materials and Methodology
This work mainly focuses on the continuous bottom thread supply where stitch
loop forms by using a half-circular rotation of “Rotary Hook/Loop Taker/Shuttle.”
The half rotations performed here by turning the middle bed shaft into a crankshaft
on the right side were facing the machine pulley. There joined a connecting rod
which is connected with a rack. The rack is being held inside a frame where it
gets a reciprocating motion from the circular motion of the crankshaft through the
connecting rod. As a result, the rack is proving a half-circular rotary motion to the
pinion (1) adjoined on a shaft that is connected with another gear (2) on the left
side and supported by a bush placed under the machine bed. The gear (2) is being
provided with the same half-circular motion from the pinion (1) directly (Fig. 1).
Gear (2) is meshing with an idle gear (3) which rotates on a shaft attached to a
bush with the bed. The idle gear (3) drives the spur gear (4) which is attached with
the loop taker. The Loop Taker gets the rotation and being hold by a cylindrical pipe
which is fastening to the body. This pipe is the ultimate bottom thread path where
one end used for thread insertion (5) and the other end exposed to the inside of the
Loop taker. The inside portion is divided into two sections; one is for loop rotation
and the other one for the bottom thread supply. The loop rotation part is modified
(Fig. 3) into a nearly half-circle shaped bracket in such a manner that the upper
thread can pass smoothly. The other section is made of another half-circle shaped
bracket with a tensioning device connected to the opening of that cylindrical pipe.
During the stitch operation, the loop taker gets the upper thread from the needle and
rotating half around and then releases it in the midway. But the upward movement
of the needle creates a tensile force that takes the loop up through the gap between
the two half-circular brackets. On that spot, the bottom thread passing through the
Fig. 1 The rack and pinion