| 摘要 |
A rasp blade 10 includes a planar sheet 12 with inner perimeter 14 and outer perimeter 16, the latter defined by the tips of a row of teeth 18. The teeth 18 extend from left side edge 20 to right side edge 22. The tips of the teeth 18 are arranged along a line of constant radius from centre 28 with the pitch of the teeth and their height from the baseline 17 (dotted line) varying from left to right. The variation can be a continuous or a variable increase along the arcuate extent of the blade. The blade has three apertures 30 for supporting the blade on pins running between end plates of a hub assembly. The blade can extend over an arc of approximately 30° up to 120° with the number of apertures depending on the arcuate extent of the blade. The blade can also include projections 40 which can be punched or pressed from the planar sheet 12 forming hollow frustro-conical extensions of the planar sheet 12 or projections 40 can be fixed separately as hollow or solid members. The tops 42 of respective projections 40 of adjacent blades provide abutting surfaces to space apart adjacent blades in a hub assembly. The top 42 can be flat, curved, round, or indented. The teeth are presented at various slant angles in a hub assembly whereby a better abrading surface is provided. Further worn blades having projections 40 can be used as spacers.
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