实践证明：设计出的剃齿刀寿命长，加工质量好，对中凹现象有明显改善。

Facts have proved that the designed shaving cutter is long-lived, good in machining quality, and effective on correcting centre-concave.

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在轴测投影中凹回转曲面的外形线可能存在尖点，这就使凹回转曲面的外形线变得复杂。

Sometimes the outline of a concave revoluted curved surface in axonometric projection would be complicated when there are some singular points on the outline.

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然而用标准渐开线齿形剃齿刀剃齿后，在工件齿形节点附近会出现不同程度的“中凹”现象。

However, after shaved by shaving cutter with true involute profiles, there are the "mid-concave" phenomena on the pitch points of shaved gear tooth profiles inevitably.

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