The pressurizing work with the wavy pattern for repeating a pressurize-lowering process and a prescribed amount raising-up of a slide 3, is performed based on a comparison between the workload of the electric servo motor 21 and a threshold value or a threshold value curve. 電動サーボモータ21の仕事量と、閾値または閾値曲線との比較に基づきスライド3の加圧下降行程と所定量上昇とを繰り返す波状パターンで加圧加工する。 - 特許庁