To manufacture straight and precise pitched twisted flat bars in a short time.

In conventional manufacturing, a flat bar was inserted in a round tube and then, with steel balls packed on both sides of the flat bar, the flat bar was twisted; by this method, however, even though the time required for twisting by a machine is short, it takes much time in the prior/post work and it is far from mass-production. So the round tube is divided into two pieces, an upper die 5 and a lower die 6, and a flat bar 2 and steel balls 3 are put into the lower die, and then the upper die is put on the lower die, and thus twisting is executed. Consequently, the working time required for the manufacturing of twisted flat bar is much shortened.