Single facer

In a single facer of the type wherein a core paper sheet introduced in a first direction is corrugated by means of a pair of upper and lower corrugated rolls, said rolls having a corrugated circumferential configuration, the corrugated core paper sheet has its crest portions applied with paste, and then a liner introduced to said single facer from a second direction different from said first direction is pasted on the corrugated paper sheet while passing between said lower corrugated roll and a pressure roll to form a single-faced corrugated sheet, the improvement wherein:

• said single facer comprises a rotatable frame supporting said pair of upper and lower corrugated rolls;
• and at least one pair of additional upper and lower corrugated rolls also is supported from said rotatable frame and has a different shape of circumferential corrugations from that of said first mentioned pair of upper and lower corrugated rolls;
• and means for rotating said rotatable frame for bringing a selected said pair of corrugated rolls into operative position with said pressure roll for performing a corrugating operation.