Patent ID: 8061015

Claim:
A method of manufacturing a stator core of an electric rotating machine, comprising the steps of: helically winding a steel plate with a plurality of magnetic pole teeth while thinning a side portion of the steel plate to form a cylindrical laminated core which has a plurality of steel sheets aligned along an axial direction of the laminated core such that the steel sheets have the magnetic pole teeth on an inner side of the laminated core and have respective thinned outer end portions spaced apart from one another on an outer side of the laminated core; and performing ironing for the thinned outer end portions of the steel sheets to form the stator core from the laminated core, wherein the step of performing the ironing includes: preparing a forming apparatus with a cylindrical work receiving member and a cylindrical work pressing member substantially coaxially disposed with each other so as to form a protrusion on at least one of contact surfaces of the members facing each other such that the protrusion protrudes along the axial direction; placing the laminated core between the contact surfaces of the work receiving member and the work pressing member so as to substantially coaxially dispose the laminated core with the work receiving member and the work pressing member; causing the work pressing member to press the thinned outer end portions of the steel sheets on the work receiving member and to deform the thinned outer end portions along a shape of the protrusion such that the thinned outer end portions are brought into contact with one another; and giving an ironing load to the thinned outer end portions, after bringing the thinned outer end portions of the steel sheets into contact with one another, to shorten lengths of the thinned outer end portions in a radial direction of the laminated core at a predetermined value.