Vertical down welding process by gravity arc welding and welding machine therefor

A downward welding machine comprising:

• a guide rail comprising;
• a main rail and a sub-rail and disposed upwardly slanted with respect to a vertical weld line;
• said sub-rail terminating at its lower end with the upper end of said main rail and being adapted such that the angle between a welding rod and a vertical weld line is continuously increased from an initial angle of at least 20.degree. up to an angle in a range between 35.degree. and 80.degree. with a descent of a welding rod holder supporting said welding rod along said sub-rail from the upper end to the lower end thereof;
• said main rail extending from the lower end of said sub-rail being straight so that said angle between 35.degree. and 80.degree. between said welding rod and vertical weld line is maintained while said welding rod holder is lowered along said main rail from the upper end to the lower end thereof;
• said welding rod holder capable of lowering gravity along said guide rail, said welding rod being securedly set in said welding rod holder so that it cannot be rotated with respect thereto;
• and
• a support base having a triangular or like shape, the lower end of said guide rail being supported on said support base at or in the vicinity of the intersection of two sides thereof other than the largest side, said support base having magnetic holder members attached to its back at the other two intersection points than said guide rail support point and also at least two positioning rods extending from its edge facing said vertical weld line, one end of each said positioning rod being rotatable with respect to said support base.