Reconditioning is performed such that the curvature of the arcuate surface of the crest on the upper corrugating roll is increased as compared before conditioning. Further, reconditioning is performed such that the curvature of the arcuate surface of the crest on the lower corrugating roll is increased as compared before conditioning. In this step, polishing is performed so as to maintain the maximum diameter of the crest on the upper corrugating roll as much as possible. Thereby, since the length of the inclined surface of the corrugating roll connecting between a crest and a trough of the upper and lower corrugating rolls and is reduced, the rate of the increase in the consumption of corrugated mediums of fluted corrugated mediums for double-faced corrugated cardboard sheets shaped by the upper and lower corrugating rolls and after reconditioning can be reduced.
1. A single facer comprising:
a first corrugating roll and a second corrugating roll being intermeshing with each other to shape a fluted corrugated medium, the first and second corrugating rolls each having a fluted outer periphery surface;
a gluing unit that applies glue to a flute tip of the fluted corrugated medium; and
a pressure unit that presses the glued fluted corrugated medium and a back liner to bond them together, in conjunction with the first corrugating roll which is located at a corrugated medium feed direction downstream side,
wherein a curvature of an arcuate surface of a crest on the second corrugating roll, which is located at a corrugated medium feed direction upstream side, is configured to be greater than a curvature of an arcuate surface of a crest on the first corrugating roll, and
wherein the single facer is capable of manufacturing a double-faced corrugated cardboard sheet wherein a curvature of an arcuate surface of the fluted corrugated medium shaped in a joint portion with a front liner is greater than a curvature of an arcuate surface of the fluted corrugated medium shaped in a joint portion with the back liner protecting an article to be packaged.
2. The single facer according to claim 1 , wherein
a difference between a curvature radius of the arcuate surface of the crest on the first corrugating roll and a curvature radius of an arcuate surface of a trough on the second corrugating roll is substantially the same as a difference between a curvature radius of the arcuate surface of the crest on the second corrugating roll and a curvature radius of an arcuate surface of a trough on the first corrugating roll.