Rotary shuttle for sewing machine

Abstract

The present invention relates to a rotary shuttle for a sewing machine, wherein a shuttle tension spring having a lower thread separation-prevention end for facilitating threading the lower thread (A) supplied from the center is coupled to the outer circumferential edge of a lower thread case ( 30 ).

1 . A rotary shuttle for a sewing machine comprising:
 a hook body ( 10 ) having a lower part to which a drive shaft is rotatably coupled;   a lower thread base ( 20 ) that is coupled to an inner circumference of the hook body ( 10 ) to rotate in a direction opposite to the hook body ( 10 ) when the drive shaft rotates and includes a concave groove ( 21 ) recessed in a downward direction on an upper part of a main wall, and a lower thread case ( 30 ) surrounding upper and lateral parts of a lower thread (A) that is inserted into the lower thread base ( 20 ) to expose an upper part thereof,   wherein:   the lower thread case ( 30 ) includes a protrusion ( 31 ) that protrudes to be inserted into the concave groove ( 21 ) by spring elastic force, a hook ( 32 ) having one end coupled to a hook coupling hole ( 31   a ) formed in the protrusion ( 31 ) and moving the protrusion ( 31 ) in an inward direction when a remaining end is lifted, a case body ( 33 ) that includes a protrusion inlet ( 33   a ) formed on an upper part thereof to allow opposite lateral parts of the protrusion ( 31 ) to be inserted thereinto and to be supported by spring elastic force and is shaped like a cylinder with an opened lower surface to insert the lower thread (A) thereinto, and a bobbin shell ( 34 ) coupled to one side of an outer circumference of the case body ( 33 ) and including a lower thread hanger ( 34   a ) bent inward at one end to guide the lower thread (A) when the lower thread (A) is pulled out; and   the protrusion inlet ( 33   a ) includes a lower thread concave groove ( 33   a ′) formed in one end thereof to be positioned inward to guide the lower thread (A) when the lower thread (A) is pulled out.   
     
     
         2 . The rotary shuttle for a sewing machine according to  claim 1 , wherein the lower thread case ( 30 ) includes a lower thread outlet hole ( 30   a ) formed through centers of the case body ( 33 ), the protrusion ( 31 ), and the hook ( 32 ) to easily pull out the lower thread (A), and an outlet hole channel ( 30   b ) formed on the protrusion ( 31 ) and the case body ( 33 ) to connect the lower thread outlet hole ( 30   a ) to an outer lateral part thereof. 
     
     
         3 . The rotary shuttle for a sewing machine according to  claim 1 , wherein the bobbin shell ( 34 ) includes a case fixing unit ( 34   b ) that extends from the lower thread hanger ( 34   a ) and is coupled to the outer circumference of the case body ( 33 ), and an elastic insert unit ( 34   c ) that extends from the case fixing unit ( 34   b ) and is in close contact with an outer circumference of the lower thread case ( 30 ) by elastic force, and the elastic insert unit ( 34   c ) includes a lower thread separation prevention end ( 341 ) that is bent inward to prevent separation of the lower thread (A). 
     
     
         4 . The rotary shuttle for a sewing machine according to  claim 3 , wherein:
 the lower thread separation prevention end ( 341 ) includes an upper prevention end ( 341 ′) bent from an upper part thereof and a lower prevention end ( 341 ″) bent from a lower part thereof to pull out the lower thread (A) from a center of an end thereof; and   the case body ( 33 ) includes a prevention end concave groove ( 33   c ) through which the lower thread separation prevention end ( 341 ) is positioned inward.   
     
     
         5 . The rotary shuttle for a sewing machine according to  claim 1 , wherein a lower thread hanger ( 33   b ) that rotates spirally and extends to position the lower thread (A) at a center thereof and to pull out the lower thread (A) from the center is provided at one side of an upper surface of the case body ( 33 ).