| 摘要 |
In a cutting tool such as an end mill, router bit, tap, thread mill, or other form of insertable rotary tooling, the edge from the center of the tool to the cutting diameter is not a straight line, but instead assumes an arcuate shape. This increases the clearance associated with the center of the tool. In one disclosed example, an arc-ended, ½-inch diameter tool according to the invention starting with a 4-degree dish angle but transitioning to a larger angle of 8 degrees results in a clearance of 0.35, an amount double to the straight-line cut of at 4 degrees, which results in a clearance of 0.0175 drop at center. Broadly, any change in dish angle from lower to higher to increase clearance is anticipated by the invention, including zero degrees to 10 degrees of more, and so forth. Although in the preferred embodiment clearance is increased by a factor of 2 or more, this is not necessary to the invention and, in fact, piecewise linear as opposed to smoothly varying transitions may alternatively be used. This arc end decreases cutting forces in both plunging and ramping operations by directing the cutting forces into a plurality of different directions. This, in turn, reduces the cutting forces and increases feed (RPM) and speed (FEED RATE) in conjunction with material removal. The design also reduces or eliminates chatter, thereby increasing cutting life and utility for the customer in terms of higher throughput and a reduction in tooling cost per part.
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