Single facer with resilient small diameter corrugating roll

The invention pertains to an apparatus for forming a single face web of corrugated paperboard. More particularly, the invention relates to a corrugating roll assembly comprising a large diameter corrugating roll (i.e. a bonding roll) and a small diameter corrugating roll in which the small diameter roll is resilient so that it is capable of deflection in the vicinity of the corrugating nip in order to cushion impact as the rolls mesh along the corrugating nip. A single facer for corrugated paperboard of the type using a very large diameter fluted bonding roll and a much smaller diameter fluted corrugating roll which engages the bonding roll to provide a corrugating nip. The small diameter corrugating roll is made to be resilient by utilizing a thin walled roll shell so that it is capable of inward deflection in the corrugating nip in order to cushion impact and absorb the deflection as the rolls interengage along the nip. This cushioning deflection absorbs vibrational movement due to chordal action of the interengaging flutes, and thereby reduces noise level and roll wear and improves the quality and consistency of corrugation. A modified flute profile, compensating for flute pitch variations between the large diameter bonding roll and small diameter corrugating roll, assures uniform flute-to-flute engagement in the corrugating nip. Strategic positioning of the supporting stub shafts for the thin walled small corrugating roll axially outside the flute patterns provides substantially uniform small roll deflection along the nip.