VACUUM PUMP AND FLANGE

摘要

Stress concentration in an impact damping structure is appropriately suppressed when it receives an impact. The impact damping structure has grooves (50) arranged on both sides of a bolt penetration section (14), or near portions on both those sides of the bolt penetration section (14) that lie along the circumferential direction of a flange (61), and also has a thin wall section (70) formed between a groove (50) and the bolt penetration hole (14). When an object receives a load, resistance force, or stress, occurring inside the object according to the load concentrates in a portion where there is a drastic change in shape. To avoid such stress concentration, portions, such as the bottoms and openings of the grooves (50), susceptible to stress concentration are formed in a circular arc shape to positively reduce the degree of stress concentration. Before the thin wall section (70) deforms, or before the thin wall section (70) damps an impact (to absorb energy), cracks caused by stress concentration and resultant failure of the thin wall section (70) can be avoided.