Fabric advancement device for sewing machines

Abstract

It is a fabric advancement device of a sewing machine, placed near one or more sewing needles and suitable for the movement of the jaws.

1 . Fabric advancement device for sewing machines, comprising a first bar at one end of which a first jaw is fixed, a first U-shaped body, open downwards, being arranged on the opposite end of the first bar, a first elongated seat being formed in the first bar, a square pin is received in said seat and is designed to act as a fulcrum for the first bar and as a runner so as to translate in the first seat, so that the first bar can move according to a horizontal oscillatory and translational movement, a rotating pin being included to which a first cylindrical body is fixed to which a first cylinder is associated which is eccentric with respect to the axis of the pin, the first cylinder being received in a homologous cylindrical seat formed in a first square block adapted to translate vertically in the first U-shaped body, characterized by the fact of comprising a second bar at one end of which a second jaw is fixed, a second U-shaped body, open towards the rear part of the second bar, and a third U-shaped body, open downwards, being comprised at the opposite end of the second bar, a second elongated seat being formed in the second bar, the square pin is received in said seat and is adapted to act as a fulcrum for the second bar and as a runner so as to translate in the second seat, so that the second bar can move according to a horizontal oscillatory and translational movement, a second cylindrical body being comprised and fixed to the rotating pin and to which a second cylinder is associated which is eccentric with respect to the axis of the pin, the second cylinder being received in a homologous cylindrical seat formed in a second square block adapted to translate vertically in the third U-shaped body, a cylindrical eccentric element being comprised and fixed to the rotating pin, received in a cylindrical seat formed in a third square block adapted to translate horizontally in the second U-shaped body. 
     
     
         2 . Fabric advancement device according to  claim 1 , wherein a parallelepiped block, integral with the first bar, is received and slides in an elongated seat formed in the second bar, so that the second bar can translate horizontally with respect to the first bar and any other relative movement between the first bar and the second bar is prevented. 
     
     
         3 . Fabric advancement device according to  claim 1 , wherein a parallelepiped block is constrained to the second bar by means of a platelet. 
     
     
         4 . Fabric advancement device according to  claim 1 , wherein the position of the first cylinder is adjustable with respect to the first cylindrical body, so as to vary the eccentricity of the first cylinder with respect to the rotating pin. 
     
     
         5 . Fabric advancement device according to  claim 1 , wherein the position of the first cylinder is adjustable with respect to the first cylindrical body by means of a first adjustment screw. 
     
     
         6 . Fabric advancement device according to  claim 1 , wherein the position of the second cylinder is adjustable with respect to the second cylindrical body, so as to vary the eccentricity of the second cylinder with respect to the rotating pin. 
     
     
         7 . Fabric advancement device according to  claim 1 , wherein the position of the second cylinder with respect to the second cylindrical body is adjustable by means of a second adjustment screw.