Screw supply device for coupled screw tightening machine

A screw supply device for a coupled screw tightening machine which tightens one of coupled screws fed to a nose portion slidably accommodated into a nose holder arranged in a front portion of a main body, said screw supply device comprising:

• a pair of feed wheels rotatably supported within the nose portion, each engageable with at least one of coupled screws;
• a pair of ratchet wheels supported concentrically with said feed wheels, rotatable in a forward/backward direction, and engageable with said respective feed wheels only when said ratchet wheels rotate in a single direction;
• a pair of guide holes formed in respective side walls of the nose holder, said guide holes extending axially;
• a pair of drive links coupled at one end thereof to a portion close to an outer edge of said respective ratchet wheels, and the other end thereof being arranged slidably along said respective guide holes;
• a pair of control plates pivotally provided in the nose holder, said control plates being engagable with the other end of said respective drive links;
• and
• a pair of springs urging said control plates respectively,
• wherein a strength of said springs is enough to temporarily stop only the retreating of said drive links when said the other end of said drive links engages with said control plates,
• wherein the other end of said drive links is in contact with a front end of said guide holes when the nose portion is on the way of advancing from a retreat end, and
• wherein said feed wheels are rotated intermittently in a coupled screw feed direction by causing said ratchet wheels to make a forward/backward rotation based on stoppage of said drive links while the nose portion is on the way of retreating and while the nose portion is in the course of advancing.