Method of manufacturing laminated ring and apparatus for measuring circumferential length difference of ring in such method

A method of manufacturing a laminated ring by severing a cylindrical drum, which comprises a sheet of maraging steel with welded opposite ends, into a plurality of rings of predetermined width, rolling said rings to a predetermined target circumferential length, correcting circumferential lengths of the rings, aging and nitriding the rings, and laminating the rings into a laminated ring for transmitting power in a continuously variable transmission, said method comprising the steps of:

• training each of the rings which is shaped to have the same circumferential length along the circumferential edges thereof, around a drive roller and a driven roller which are displaceable in directions toward and away from each other and a correction roller disposed intermediate between said drive roller and said driven roller and displaceable in directions perpendicular to the directions in which said drive roller and said driven roller are displaceable;
• displacing said drive roller and said driven roller away from each other under a given force, determining an actual circumferential length of the ring while keeping the ring taut around said drive roller and said driven roller, determining the difference between the actual circumferential length of the ring and the target circumferential length for the rolled ring as a reference value, and calculating a distance that said correction roller is to be displaced depending on the difference between the actual circumferential length and the reference value;
• and
• holding said drive roller and said driven roller spaced by a predetermined distance from each other, and displacing said correction roller in a direction perpendicular to the directions in which said drive roller and said driven roller are displaceable and to extend said ring, by the calculated distance depending on the difference between the actual circumferential length and the reference value, for thereby correcting the circumferential length of the ring.

An apparatus for measuring the difference between the circumferential lengths of circumferential edges of each of rings produced by severing a cylindrical drum, which comprises a sheet of maraging steel with welded opposite ends, into a plurality of rings of predetermined width, and rolling said rings to a predetermined target circumferential length, comprising:

• a pair of support means for supporting the ring trained therearound;
• load imparting means for imparting a tensile load to said ring by spacing said support means away from each other;
• first load measuring means mounted on one of said support means, for abutting against an inner surface of one of the circumferential edges of the ring and measuring a load imparted to said one of the circumferential edges of the ring;
• second load measuring means disposed in juxtaposed relationship to said first load measuring means, for abutting against an inner surface of the other circumferential edge of the ring and measuring a load imparted to said other circumferential edge of the ring;
• and
• circumferential length difference detecting means for detecting the difference between the circumferential lengths of the circumferential edges of the ring based on the difference between the load measured by said first load measuring means and the load measured by said second load measuring means when said difference between the loads is maximum.