Device for correcting circumferential length of metal ring

An apparatus for correcting the circumferential length of a metal ring, comprising:

• a drive roller and a driven roller positionable closely to each other for training a metal ring therearound;
• a correcting roller disposed between said drive roller and said driven roller;
• first displacement applying means for displacing said drive roller and said driven roller away from each other when the metal ring is trained around said drive roller, said driven roller, and said correcting roller;
• spacing means for spacing said drive roller and said driven roller a predetermined distance from each other when said drive roller and said driven roller are released from being displaced by said first displacement applying means;
• second displacement applying means for displacing said correcting roller in a direction perpendicular to the direction in which said drive roller and said driven roller are displaced by said first displacement applying means and also to extend said metal ring, thereby to correct the circumferential length of said metal ring while said drive roller and said driven roller are being spaced said predetermined distance from each other;
• and
• third displacement applying means for displacing said drive roller and said driven roller toward each other when said drive roller, said driven roller, and said correcting roller are released from being displaced by said first displacement applying means and said second displacement applying means.