Tham khảo tài liệu 'gear noise and vibration episode 1 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Marcel Dekker Inc. Madison Avenue New York New York 10016 Copyright Marcel Dekker Inc. All rights reserved. 8 Recording and Storage Is recording required For much work especially for initial investigations and development there is little point in recording masses of data whether . or vibration. Displaying the information dfrectly on an oscilloscope preferably triggered to synchronise with 1 rev of pinion or wheel is very valuable and should never be omitted. It is especially usefill when the problem occurs at particular points in the revolution. A typical example is the noise of a timing drive clatter on a diesel engine. Even more important is the information from the raw signal to see whether noise or vibration is due to isolated impulses or to steady excitation. Steady vibration typically at one-per-tooth frequency is easily recorded by hand since the frequency is obvious and there is a single Figure for amplitude. A . trace such as that sketched in Fig. will give an immediate value for eccentricity and for the expected 1 tooth so no data logging is requfred whereas a trace such as that in Fig. needs recording for detailed analysis. If a condition is transient . scuffing or if there is a suspicion that a small regular defect is hidden underneath steady or irregular vibration then it is essential to record for detailed subsequent analysis. It is not unknown for the signal-to-noise ratio to be -20 dB or even lower in a gearbox. Fig Simple . trace. 121 Copyright Marcel Dekker Inc. All rights reserved. Marcel Dekker Inc. 270 Madison Avenue New York New York 10016 122 Chapter 8 1 rev Fig Complicated vibration recording. Noise in this context is used to describe any electrical or mechanical vibration which is not the vibration of interest. Digital versus analog Until 20 years ago analog tape recording completely dominated the field of data recording. Digital storage was expensive and restricted in size and sampling rate so there was
