MECHANICAL SYSTEM NATURAL FREQUENCY REGULATING METHOD

摘要

PURPOSE:To easily lower the rigidity of a mechanical system and regulate its natural frequency by replacing a tap bolt on the field and weakening the bonding strength of flanges in a mechanical system in which the lifting pipe of a vertical shaft pump is integrally bonded with upper and lower flanges. CONSTITUTION:When a natural frequency is to be varied to the maximum, a tap bolt 2A is prepared and the external thread part 21 on the lower end of this bolt 2A is screwed into the tapped hole 1a of a lower flange 1 and the stepped face 23A on the bottom end of its straight body part 33 is brought into contact with the top face of the lower flange 1. The bonding condition is in such a way that a gap 5 having a height h1 corresponding to a dimension within the depth dimension h0 of a recessed part 4 is formed in between the bottom face of a bolt head part 22 and the bottom face 4A of the recessed part 4. In such a bonding condition, the bonding strength through which the upper and lower flanges 3, 1 are strongly brought into pressure contact with each other can be remarkably weakened lowering the rigidity of a system. Hence, the natural frequency of each system can be regulated to effectively avoid resonance phenomenon.