Abstract: By taking a 25 kJ counterblow hydraulic hammer as specific model, a method for analyzing and studying dynamic characteristics of counterblow hydraulic hammer is put forward by combining theoretical calculation with ambient excitation testing. According to established mechanical frame model and exercising theoretical modal calculation, the first ten step natural frequencies and corresponding vibration modes of this frame are obtained. Then, on-line modal parameter identification of 25 kJ counterblow hammer is performed by employing the response data of frame reference points, and the first ten step natural frequencies and corresponding vibration modes of this frame under operating environment are obtained. The relative error between theoretical modal parameters and experimental modal parameters is below 1%, and the vibration modes of all steps are consistent. The study shows that dynamic characteristic data of counterblow hydraulic hammer can be visually and efficiently obtained by using modal analysis, which provides a theoretical basis for improving structure design, working reliability and service life of the equipment. Self-developed 25 kJ counterblow hydraulic hammer (C83 series) has good dynamic performance, with even overall rigidity and mass distribution.

Key words: Ambient excitation, Counterblow hydraulic hammer, Dynamic characteristics, Modal analysis