在机械工业中，由圆柱面运动生成的包络面是一种常见的曲面。由于机械磨损，圆柱会变小从而需要及时更换。这是一笔很大的浪费。因此很自然引出如下的问题：由一柱面运动生成的包络面能否由另一更小的圆柱面运动生成。我们对这一问题进行了研究，发现了一个充分条件，并通过一反例说明了在一般的情形下对该问题的回答是否定的。 In the mechanical industry, envelopes generated by cylindrical motions are a common surface. Due to mechanical wear, the cylinder becomes smaller and needs to be replaced in time. This is a great waste. It is therefore naturally a question of whether the envelope generated by one cylindrical motion can be generated by another, smaller cylindrical motion. We have studied this issue and found a sufficient condition, and through an example of counter-examples, we can say that the answer to this question is negative under normal circumstances.