Flux cored wire and manufacturing method thereof and manufacturing device thereof

1. A flux cored wire comprising:

an inner tubular body formed with a first flat strip by curling up side edges of the first flat strip into a tubular body having a first seam and filled with flux inside; and

an outer tubular body formed with a second flat strip by curling up side edges of the second flat strip into a tubular body having a second seam and wrapping around the inner tubular body in tight contact,

wherein the first and second seams of the inner tubular body and the outer tubular body are located at different positions,

wherein diameters of the inner tubular body and the outer tubular body are reduced by a drawing process,

wherein the first and second flat strips of the inner tubular body and the outer tubular body are rolled so that longitudinal edges contact with opposite longitudinal edges to form circular cross-sections, and a thickness of a wall of the outer tubular body is greater than a thickness of a wall of the inner tubular body, and

wherein a ratio of the flux filled inside of the inner tubular body is between 30% to 40% by weight of the entire inner tubular body including the flux, and wherein a ratio of the flux filled inside of the inner tubular body is between 12% to 15% of the total weight of the inner tubular body including the flux and the outer tubular body.

2. The flux cored wire of claim 1 , wherein the first and second seams of the inner tubular body and outer tubular body are arranged at different positions away from each other by an interior angle of at least 60 degrees from a center of the inner tubular body and outer tubular body.

3. The flux cored wire of claim 1 , wherein the second seam of the outer tubular body is removed by welding.

4. The flux cored wire of claim 2 , wherein the interior angle is about 90 degrees.

5. The flux cored wire of claim 1 , wherein the inner tubular body and the outer tubular body are formed as an integrated body by the drawing process.

6. The flux cored wire of claim 1 , wherein the thickness of the wall of the outer tubular body is 0.6-1.2 millimeters, and the thickness of the wall of the inner tubular body is 0.4-0.8 millimeters.

7. A flux cored wire comprising:

an inner tubular body formed with a first flat strip by curling up side edges of the first flat strip into a tubular body having a first seam and filled with flux inside; and

an outer tubular body formed with a second flat strip by curling up side edges of the second flat strip into a tubular body having a second seam and wrapping around the inner tubular body in tight contact,

wherein the first and second seams of the inner tubular body and the outer tubular body are located at different positions away from each other by an interior angle of at least 60 degrees from a center of the inner tubular body and outer tubular body, and

wherein a ratio of the flux filled inside of the inner tubular body is between 30% to 40% by weight of the entire inner tubular body including the flux, wherein a ratio of the flux filled inside of the inner tubular body is between 12% to 15% of the total weight of the outer tubular body and the inner tubular body including the flux.

8. The flux cored wire of claim 7 , wherein the outer tubular body has a wall thickness equal to or greater than a wall thickness of inner tubular body.

9. The flux cored wire of claim 8 , wherein the thickness of the wall of the outer tubular body is 0.6-1.2 millimeters, and the thickness of the wall of the inner tubular body is 0.4-0.8 millimeters.

10. The flux cored wire of claim 7 , wherein the interior angle is about 90 degrees.

11. The flux cored wire of claim 7 , wherein diameters of the inner tubular body and the outer tubular body are reduced by a drawing process.

12. The flux cored wire of claim 11 , wherein the inner tubular body and the outer tubular body are formed as an integrated body by the drawing process.