| 摘要 |
1,179,217. Machine tool damping. CINCINNATI MILLING MACHINE CO. 6 Sept., 1968 [12 Oct., 1967], No. 42648/68. Heading B3B. A damping unit for controlling vibrations, e.g. in the overarm 9 of a milling machine, comprises at least one viscoelastic absorber element, e.g. 27 or 28 of varying cross-section interposed between a damper mass 23 and a support location 25, 26 on an adjustably positioned support means, relative movement between the support means and absorber element altering the working height h of the absorber element (Fig. 2) to alter its stiffness and thereby the frequency of the damping unit. The support means may, as shown, comprise a shaft 24 with shoulder portions 25, 26 and adjustment of the positions of the shoulders relative to the absorber elements may be by means of a screw 32 or alternatively, cam means (Fig. 19a, not shown), responsive to movements of the overarm, automatically vary the support locations to vary the frequency of the damping unit according to a predetermined relationship. Alternatively (Fig. 20, not shown) electrical sensing means responsive to the natural vibration of the machine may be used to control the damping units accordingly. The absorber elements may be straight and of generally triangular section (Figs. 14-18, not shown), or annular, or segmental surrounding the damper mass (Figs. 12, 13, not shown). The damper masses may be supported by springs so as substantially to relieve the absorber elements of static loading. |
