Refiner plates with logarithmic spiral bars
AssigneeDurametal Corporation
InventorPeter Antensteiner
Life of this patent
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Abstract
A special shape of bars on refining discs or plate segments (54) of a rotating disc refiner (10) is disclosed including a plurality of bars (76) generally extending outwards toward the outer end of the disk across its surface, arranged in a single, two or more radial zones (64, 66, 68), the plurality of the bars within a zone being curved with the shape of a logarithmic spiral. Disc refiners including such refining discs are also disclosed.
Claims14
A refining disc having a working surface, a radially inner end and a radially outer end, the working surface including a plurality of bars having inner and outer ends, laterally spaced by intervening grooves, and extending generally outwardly toward said outer end across said surface, said bars and grooves forming a pattern defining at least one radially extending substantially annular zone and wherein each of at least a majority of said plurality of bars in said zone being curved with the shape of a logarithmic spiral from the inner to the outer end of said bars, wherein said shape of said bars conforms within manufacturing tolerances to the mathematical expression in polar coordinates:
- r=a·ek·φ
- where k=0→circlek=cotα and
- “r” is the radial position along the centerline of the bar, “a” is a scale parameter for r and α is the intersecting angle between any tangent to the curve and the generatrix of the coordinate system.
A plate segment for a disc of a rotary disc refiner, comprising a working surface including a plurality of bars having inner and outer ends and laterally spaced by intervening grooves, said bars and grooves forming a pattern defining at least one radially extending zone and wherein each of at least a majority of said bars in said zone being curved with the shape of a logarithmic spiral from the inner to the outer end of said bars, wherein the shape of said bars conforms within manufacturing tolerances to the mathematical expression in polar coordinates:
- r=a·ek·φ
- where k=0→circlek=cotα and “r” is the radial position alone the centerline of the bar, “a” is a scale parameter for r and α is the intersecting angle between any tangent to the curve and the generatrix of the coordinate system.
Dependencies are inferred from the claim text.