Method of producing iron core and apparatus for producing iron core

A multi-workstation iron core-producing apparatus in combination with an iron strip that blanks iron cores from the iron strip such that a longitudinal direction of the iron cores is inclined relative to a direction of a width of the iron strip at an acute inclination angle, the multi-workstation iron core-producing apparatus comprising:

• a guide that guides the iron strip sequentially through a plurality of workstations along a longitudinal direction of the iron strip;
• a first workstation having caulking portion-forming holes and punches that intrude into the respective caulking portion-forming holes and that simultaneously form first plural sets of caulking portions at a predetermined pitch in the iron strip, wherein a longitudinal direction of rows of the caulking portion-forming holes and the punches in the first workstation is inclined at an acute angle relative to the direction of the width of the iron strip;
• and
• a second workstation that includes a die, a die holder for fixing the die, a punch, and a blanking drop hole formed in the die to form a first iron core from the iron strip by punch blanking, wherein the blanking drop hole extends in a longitudinal direction and is inclined at the acute angle relative to the direction of the width of the iron strip,
• a third workstation having a punch that intrudes into caulking portion-forming holes and that simultaneously forms second plural sets of caulking portions in the iron strip at the predetermined pitch in the iron strip;
• and
• a fourth workstation that forms a second iron core by blanking from the iron strip in which the second plural sets of caulking portions were formed at the third workstation,
• wherein the guide includes engagement projections for engagement of pilot holes formed at a predetermined pitch in opposite side edge portions of the iron strip,
• wherein the pilot holes in the opposite side edge portions of the iron strip are not directly opposite one another, and
• wherein a line that intersects the pilot holes on a first side edge portion of the iron strip also intersects the first iron core, and a line that intersects the pilot holes on a second side edge portion of the iron strip also intersects the second iron core.