Spiral groove pattern refiner plates

A pie segment of a fibrous stock refiner disc fabricated about an axis of revolution and having a serrated stock working face on one planar surface thereof, said face having a stock distribution groove segment of a circular ring developed about said axis and disposed radially between said axis and an outer peripherial boundary of said disc segment, serrations between said distribution groove and said outer boundary comprising an alternating series of curved bars and channels extending continuously from said groove to said outer boundary, each bar having substantially the same thickness at said groove as at said boundary and each channel being a substantially constant width arc of a first circle developed about a first center point located on the locus of a second circle, said second circle being developed about said axis of revolution.