| 摘要 |
<p>1375859 Altering physical properties A G HEBEL JNR and A G HEBEL 6 Dec 1971 [7 Dec 1970] 56505/71 Heading B3V In a method of stress relieving a metallic object, the object is first vibrated over a range of frequencies to produce a plot of vibrational response as a function of frequency comprising at least one hill, which has a resonant peak and slopes extending upwardly and downwardly towards and away from the peak respectively with increasing frequency, and to perform the stress relief the object is vibrated at a selected frequency within a range defined by one of the slopes. A metal beam 10 is supported by rubber pads 14 and a vibrator 16 is clamped to the beam at position A. The vibrator comprises a variable speed motor driving an eccentric and the vibration is detected by a pick-up 18 also clamped to the beam. The motor is run through a speed range, which results in the beam vibrating through a frequency range of 0-10,000 CPM, and the amplitudes indicated on a meter 26 are plotted against frequency to give a curve 30. Effective stress relief can only be given by vibrating the beam at a frequency within a range defined by one of the slopes 36a-36d or 38a- 38d. A preferred location is approximately one third the way up one of the upward slopes 36a- 36d and best results are obtained where the downward slope is steep relative to the upward slope, i.e. at location 39. During the stress relieving operation, the frequency peaks shift to the locations shown in curve 44. This shift is shown as a change in meter reading and when this has stabilized, stress relief is complete. The vibrator is moved successively to positions B, C, D and the operation is repeated. Other metal articles may be similarly stress relieved, e.g. spoked wheels, flat discs and tubular rails joined side-by-side by angle sections, Figs. 2-4 (not shown).</p> |
