Effect of tip path overlap on ring debarker performance of frozen and unfrozen black spruce logs

ABSTRACT

The effect of the tip path overlap on debarking quality of unfrozen and frozen black spruce logs was studied. The power, energy consumption, and torque were also measured for both temperature conditions. The experiment consisted of debarking logs using three overlaps (8, 27, and 43%) at two temperatures (−12°C and +20°C). Debarking quality was evaluated by the proportion of bark remaining on log surfaces and by the amount of wood in bark residues. Log characteristics (dimensions, eccentricity, and knot features), bark/wood shear strength (BWSS), moisture content, and basic densities of sapwood, inner, and outer barks were measured and treated as covariates. Experiments revealed that tip path overlap affects debarking quality for both temperature conditions: the amount of bark remaining on log surfaces decreased, and the proportion of wood in bark residues increased as tip path overlap increased. In addition, the effects of bark/wood shear strength, the proportion of knot area and sapwood, inner and outer barks densities, and moisture content on debarking quality criteria were analyzed. The mean power, energy consumption, and torque increased as the tip path overlap increased. These parameters were also positively affected by the log diameter and BWSS for frozen logs. The results give helpful information to improve debarking quality within the studied range of overlaps, log characteristics, and debarking parameters with efficient energy use.

KEYWORDS:

• Ring debarker
• tip path overlap
• bark/wood shear strength
• debarking quality
• energy consumption

Acknowledgments

The Natural Sciences and Engineering Research Council of Canada (NSERC) and DK-SPEC Inc provided funding for this project. In addition, the authors thank DK-SPEC Quebec, Canada, for providing the knife arms and tips. The authors also thank Rentry Augusti Nurbaity, Félix Pedneault, Jean Ouellet, Daniel Bourgault, and Réjean Demers for their valuable assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Mitacs and Dk-Spec.