Punch processing method for laminated iron core and method for manufacturing laminated iron core

1. A punch processing method for a laminated iron core, comprising:

sequentially feeding the steel sheets to a mold; and

performing a plurality of processes in the mold, including:

fixing the steel sheets being stacked to each other at a first fixing part that is positioned outside a closed curved line corresponding to an outermost periphery of the laminated iron core and a second fixing part that is positioned in a portion that finally serves as the laminated iron core, such that the steel sheets include a number of pairs of the first fixing part and the second fixing part which satisfy a requirement that a length of a line segment connecting the first fixing part with the second fixing part is 400 times or less of an average sheet thickness of the steel sheets; and

performing punch processing on the outermost periphery of the laminated iron core while the steel sheets are stacked, wherein

the number of pairs is 0.5 or more per 100 mm in length of the closed curved line on average, and

for the number of pairs of the first fixing part and the second fixing part which satisfy the requirement, when a shorter distance out of a distance between the first fixing part and the closed curved line and a distance between the second fixing part and the closed curved line is determined to be a distance between a fixing part and the closed curved line, an average value of the distance between the fixing part and the closed curved line is made to 250 times or less of the average sheet thickness of the steel sheets.

2. The punch processing method for the laminated iron core according to claim 1 , wherein a method of fixing the steel sheets at the second fixing part is a method of fixing using a caulking projection to form a laminated iron core.

3. A method for manufacturing a laminated iron core, the method comprising:

manufacturing a laminated iron core by laminating and integrating a steel sheet to which punch processing is performed using the punch processing method for the laminated iron core, including:

sequentially feeding the steel sheets to a mold; and

performing a plurality of processes in the mold, including:

fixing the steel sheets being stacked to each other at a first fixing part that is positioned outside a closed curved line corresponding to an outermost periphery of the laminated iron core and a second fixing part that is positioned in a portion that finally serves as the laminated iron core, such that the steel sheets include a number of pairs of the first fixing part and the second fixing part which satisfy a requirement that a length of a line segment connecting the first fixing part with the second fixing part is 400 times or less of an average sheet thickness of the steel sheets; and

performing punch processing on the outermost periphery of the laminated iron core while the steel sheets are stacked, wherein

the number of pairs is 0.5 or more per 100 mm in length of the closed curved line on average, and

for the number of pairs of the first fixing part and the second fixing part which satisfy the requirement, when a shorter distance out of a distance between the first fixing part and the closed curved line and a distance between the second fixing part and the closed curved line is determined to be a distance between a fixing part and the closed curved line, an average value of the distance between the fixing part and the closed curved line is made to 250 times or less of the average sheet thickness of the steel sheets.

4. A method for manufacturing a laminated iron core according to claim 3 , wherein a method of fixing the steel sheets at the second fixing part is a method of fixing using a caulking projection to form a laminated iron core.