Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Patent
1997-01-21
1998-05-05
Raevis, Robert
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
73862041, 73862324, 73862624, 7386249, 356 355, G01L 300
Patent
active
057476993
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method for measuring torsional stresses and/or axial stresses on a rotating shaft or a comparable work piece whereby subsequently the corresponding torque moments and/or bending moments are determined.
For monitoring rotating shafts (or a comparable rotating workpiece) it may be necessary to measure torsional stresses and/or axial stresses to determine therefrom the corresponding torque moments and/or bending moments in order to find out which loads are acting on the shaft. In order to be able to measure the aforementioned values, it has been necessary in the past to provide attachments on the shaft or to impose by flanging special measuring shafts. This is possible only with a great technical expenditure. Furthermore, these measuring devices are very susceptible to breakdown. Since furthermore with the known measuring technics electrical current is used, explosion prevention is not always ensured.
In EP 0 578 422 A2 a method for measuring torque of, for example, a shaft is disclosed. The measuring method suggest to arrange an optical sensor element on the workpiece to be examined. A radiation source loads the sensor element with light while a corresponding detector receives light reflected by the sensor element. As soon as torque is exerted on the workpiece, the sensor element is subjected to a corresponding deformation, and this has the consequence that the polarization of the radiation within the sensor element is changed. For determining the torque, the intensity or the changes in the spectral distribution of the radiation is measured by the detector.
In GB 2 125 958 A a further method for measuring the torque on a shaft is disclosed. For this purpose, two reflectors with axial spacing relative to one another are arranged on the shaft and they are irradiated with light. The light impulses reflected by the reflectors are received by corresponding light detectors whereby the time intervals between the respective light impulses vary with the torque acting on the shaft. Thus, depending on the measured time intervals the currently present torque can be calculated with a corresponding microprocessor and can be displayed.
In DE 30 11 700 A1 a device for measuring the load-dependent torque of a rotating shaft is disclosed. In this measuring device there are also two axially spaced reflectors arranged on the rotating shaft which are loaded with light, and, by measuring the reflected light, the torsion of the rotating shaft based on changing angular distance of the two reflectors is measured and from this the torque is calculated.
Based on this, it is an object of the invention to provide a simple method for measuring the torsional stresses and/or axial stresses on a rotating shaft or a comparable workpiece.
SUMMARY OF THE INVENTION
The inventive method for measuring torsional stress and axial stress of a rotating workpiece is primarily characterized by the steps of: that connecting lines between reflectors of each reflector pair are slanted relative to one another; produce reflected and interfering light beam pairs for each one of the reflector pairs; pair; and difference.
In the step of arranging four reflectors are provided such that two reflectors define one of the reflector pairs and the other two reflectors define the other reflector pair.
Alternatively, in the step of arranging three reflectors are provided for defining two reflector pairs such that one of the three reflectors is common to both reflector pairs.
The step of arranging may include providing the reflectors in the form of impressions in the workpiece, such as concave impressions or equal-sided pyramid-shaped impressions with four facets.
The step of arranging may include connecting a carrier to the workpiece and providing the reflectors in the form of impressions in the carrier, such as concave impressions or equal-sided pyramid-shaped impressions with four facets.
A first one of the connecting lines extends at an angle of +45.degree. to the axis of rotation and a second one of the con
REFERENCES:
patent: 4432239 (1984-02-01), Bykov
patent: 5001937 (1991-03-01), Bechtel et al.
patent: 5438882 (1995-08-01), Karim-Panahi et al.
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