Measuring and testing – Vibration – Resonance – frequency – or amplitude study
Reexamination Certificate
1999-03-23
2001-09-18
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
Resonance, frequency, or amplitude study
C073S001820, C073S012010
Reexamination Certificate
active
06289736
ABSTRACT:
FIELD OF THE INVENTION
The present invention is concerned with the ultrasonic technology and can be adapted for various uses, more particularly for technological processes employed by machine building, shipbuilding, and bridge engineering for production of welded structures, especially those operating on the ultimate stress limit, as well as for relaxation strengthening of welded structures.
DESCRIPTION OF THE PRIOR ART
Known is the method for Ultrasonic Impact Treatment (UIT) with automatic adjustment of resonant oscillation system power source frequency. Minimization of power consumed and automatic control over the required quality of ultrasonic treatment of welded structures and other objects are provided through processing of a return signal. A control parameter is the amplitude of the return signal, which is proportional to that of electromechanical transducer output mechanical oscillations. The level of the latter is maintained within the range of the preset critical values through the voltage pulse-width modulation at a carrier resonant frequency of an oscillation system under load (e.g. RF(RU)patent
1
12031144, Int. Cl.6 C21D 1/04, 11/00 of May 11, 1990).
This method for electroacoustic transducer excitation is inefficient with discontinuous load and susceptible to external influences upon the amplitude of transducer ultrasonic displacements.
The most close technical solution to that described above is the method for electroacoustic transducer excitation at discontinuous load, which lies in that the excitation electric impulses are supplied to the transducer at resonant frequency or frequency multiple of the resonant one, while impulse length is not more than a half-period of transducer mechanical oscillations. The supply of impulses is periodically terminated and then, in response to a return striction signal, is resumed again at an adjusted frequency (see, for example, author's certificate of the USSR No. 1271585, A 06A 1/06 of 1986). The current impulses are supplied to the transducer synchronously with the oscillations in a electric circuit formed by the transducer and the compensator.
The deficiency of this method is that the frequency of electric resonance in the circuit formed by the concatenated transducer and compensator differs from transducer intrinsic mechanical oscillation frequency due to influence of various external factors such as load, temperature, viscosity, etc. The transducer efficiency coefficient at electric circuit resonant frequency is considerably reduced with the increase in difference of frequencies of the transducer mechanical oscillations and resonant oscillations of electric circuit.
SUMMARY OF THE INVENTION
The method aims to solve the problem of efficient excitation of the oscillation system at its resonant frequency under conditions of discontinuous load. The method lies in that the excitation electric impulses are supplied to the transducer at resonant frequency or frequency multiple of the resonant one, while impulse length is not more than a half-period of transducer mechanical oscillations. The supply of impulses is periodically terminated and then, in response to a return striction signal, is resumed again at an adjusted frequency.
The method is distinguished in that the supply of excitation impulses is resumed at the time corresponding to the highest transducer sensitivity at frequency and in oscillation phase adjusted to those of the transducer at this time.
The invention enhances the efficiency of the transducer excitation and reduces the influence of external factors upon the change of ultimate amplitude of its ultrasonic displacement in the course of operation under load. This allows for significant widening of the range of applications of the UIT method, automating the selection of optimal treatment modes to achieve the required quality of a surface treated depending on its plastic deformation conditions, and for lowering power consumption.
For the reason that the combination of essential features of the method, described in the method claim, is currently unknown, this invention conforms with novelty criterion (N). Since no technical solutions are identified to have the features matching the distinctive features of the present invention, it is deemed to conform with the invention level criterion (IS). The reasons stated below in the Paragraph on Industrial Applicability prove that the invention conforms with industrial applicability criterion (IA).
REFERENCES:
patent: 3918442 (1975-11-01), Nikolaev et al.
patent: 4973876 (1990-11-01), Roberts
patent: 5766137 (1998-06-01), Omata
patent: 6036796 (2000-03-01), Halbert et al.
patent: 6171415 (2001-01-01), Statnikov
Breiner & Breiner L.L.C.
Saint-Surin Jacques
UIT, L.L.C. Company
Williams Hezron
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