| 摘要 |
PURPOSE:To permit to rotate the runner in a wide range of rotating number without causing resonance by a method wherein the rigidity of main panel, consisting of a thin plate, is improved to increase the intrinsic frequency thereof. CONSTITUTION:In order to increase the intrinsic frequency of the runner, draw formings are applied to the main panel 1 as shown by numerals 9, 10 to increase the strength thereof as a flat plate by the work-hardening caused by the draw forming. The effect of the work-hardening is increased by adding the protrusion of the stepped part 10. According to this method, the main panel 1 may be adopted to a machine having a large diameter, airflow amount and air pressure even though the main panel 1 is made by the thin plate. Further, wrinkles, generated upon the draw forming, may be absorbed by making a step at the drawn parts 9, 10 and the resonance of the runner may be eliminated within the wide range of rotating number. |
