Automated Condition Monitoring with Remaining Lifetime Assessment for Wire Ropes in Ladle Cranes

The hazards and deterioration of operating wire ropes on overhead cranes, which articulate the ladle in the basic oxygen steelmaking process and are subjected to intensive periodic loads and exposure to high temperatures, are discussed. An automated condition monitoring system (ACMS) based on a magnetic flux leakage testing (MFL) flaw detector permanently installed on the rope under test is used. An algorithm of the rope’s residual tensile strength assessment is provided. A specially developed software that submits a decision on the rope’s condition to the crane operator is described. The practice of combining magnetic rope testing (MRT) and tensile strength analysis for the quantitative assessment of rope condition is reviewed. Practical issues are also discussed, such as how to establish the condition monitoring process, set loss thresholds for rope metallic cross-sectional area, and safely prolong the service life of rope.

Разработка метода ультразвукового контроля качества пластиковых изделий, полученных методом ротационного формования

At present, the technology of rotational molding of plastics is rapidly developing in the world. However, with this method of processing, it is possible for "microbubbles" to appear in the walls of the products, which significantly impair their quality. In this work, to assess the quality of plastic products, the method of ultrasonic testing (UT) was applied. Using the echo method at an operating frequency of 2.5 MHz, samples of various degrees of quality were analyzed. It was found that the propagation speed of the ultrasonic signal does not depend on the degree of product quality and is 2330 ± 10 m / s. It was found that the larger the parameter of the surface roughness Rz of the products (from 2.5 to 20 μm), the smaller the amplitude of the background signal Аа becomes. An unfinished sample is determined by the Aa parameters (from -6.0 to -15.0 MHz). A reference sample (ρ = 0.942 g / cm3) has been determined with which it is possible to calibrate the flaw detector, its Aa = 0 dB at an operating frequency of 2.5 MHz. Revealed the relationship between the density / baking of products and the amplitude of the bottom signal. The possibility of detecting internal defects of products by the ultrasonic inspection method has been proved. A new method is proposed for identifying suitable products in production, with the help of which it is possible to determine the degree of product quality.

INVESTIGATION PARAMETERS ULTRASONIC DEVICE ON PHASED ARRAYS. FOCUSING MODES FOR ULTRASONIC DEVICE TYPE OF OMNISCAN

The article is devoted to possibilities of regular focusing of Omniscan device on phased arrays. Questions are raised about evaluation of testing results when using linear and sector scan-ning with different focus parameters. The question of size near-field for phased arrays and asso-ciated choice of focus mode is discussed. The article is based on experiments conducted on samples with artificial reflectors at the same size, but different in type: a non-directional reflector (a side-drill hole) and a directional reflector (a flat-bottomed reflector), located at the same depth. The study was conducted for transducers with different frequencies. Families of curves of the signal amplitude dependence are obtained: on depth reflector, on focus depth setting, and on type reflector. The results emphasize need for precise focusing with-in the near-field of the transducer for small thicknesses or shallow depth of occurrence of discontinuities, and large variability in choice of focusing for depths in far-field. The study notes a significant difference in values of depth reflector at different focusses at a fixed position of transducer. In this article, in addition to considering possibility of focusing a flaw detector with phased arrays, the focus is on interpretation of results and reliability of testing in the analysis and comparison data. An integral part of the technological testing protocol for phased array is the depth of focus and the type of scanning. The obtained data do not depend on the frequency of transducer, which means that conclusions are applicable to general range of flaw detectors on phased arrays.

APPLICATION OF INCLINED LONGITUDINAL ULTRASONIC WAVES TO IMPROVE THE EFFICIENCY OF RAIL FLAW DETECTION

The article is devoted to the question of rail ultrasonic testing confidence. At present there is a range of flaw orientation angles in within which the testing is absent and, therefore such flaws can be lost. To except this drawback the current sound testing scheme in flaw detector railcars is to be supplemented with inclined probes exciting longitudinal wave. Experimental checks using echomethod showed the good results on an October railway section with flaw models and on a loaded Zabaycalskaya railway section. The next step was idea of mirror-shadow method using as well as echomethod by turning of probes towards each other. Envelope analysis of bottom signals allows receiving additional information about flaws: location depth of its center and form. But using of pair of probes was not enough for unambiguous definition of other geometric flaws characteristics. That is why the bottom signal envelope of straight probe was to be analyzed additionally. A mobile (as well removable) searching system of rail checking means has such probe as a rule. In the process of writing the article previously obtained formulas to calculate depth, inclination angle and plane size of revealed flaw were modified. Values changing during testing process are absent now. Algorithm of flaws identification on the basis of bottom signals envelope is given. The approach is confirmed by mathematical modeling in CIVA-UT.

К вопросу об интерпретации эхограмм ультразвукового импульсного дефектоскопа

The echogram of an ultrasonic pulse flaw detector is considered as an auto-convolution of an acoustic signal radiated into the load and received by a damped piezo plate. The reconstruction of the acoustic signal makes it possible to determine the drift of the reflection coefficients of ultrasonic vibrations at the boundaries of the piezo plate-load and piezo plate-damper, for example, when checking transducer during manufacture, under operating conditions. A method for evaluating the sensitivity of the transducer is proposed.

METHOD OF REFERENCE SIGNALS CREATING IN NON-DESTRUCTIVE TESTING BASED ON LOW-SPEED IMPACT

The article describes the approach to the formation of a simulation model of information signals, which are typical for objects with different types of defects. The dispersive analysis of the signal spectrum components in the bases of the discrete Hartley transform and the discrete cosine transform is carried out. The analysis of the form of the reconstructed information signal is carried out depending on the number of coefficients of the spectral alignment in Hartley bases and cosine functions. The basis of orthogonal functions of a discrete argument is obtained, which can be used for the spectral transformation of information signals of a flaw detector. A method of simulation of information signals has been developed and experimentally investigated, which allows taking into account the deterministic and random components of the characteristics of real information signals. References 24, figures 13, tables 3.

ULTRASOUND INSPECTION OF COMPOSITE MATERIAL PRODUCTS

Polymer composite materials are used in modern rocket and space engineering, but the question of technical diagnostics of such products is very acute. The study of PCM products showed that the use of a portable ultrasonic flaw detector with high-frequency transducers is possible, but on small particles (product areas) of control.

An Algorithm for Correcting Levels of Useful Signals on Interpretation of Eddy-Current Defectograms

To ensure traffic safety of railway transport, non-destructive tests of rails are regularly carried out by using various approaches and methods, including eddy-current flaw detection methods. An automatic analysis of large data sets (defectograms) that come from the corresponding equipment is an actual problem. The analysis means a process of determining the presence of defective sections along with identifying structural elements of railway tracks in defectograms. This article continues the cycle of works devoted to the problem of automatic recognizing images of defects and structural elements of rails in eddy-current defectograms. In the process of forming these images, only useful signals are taken into account, the threshold levels of amplitudes of which are determined automatically from eddy-current data. The previously used algorithm for finding threshold levels was focused on situations in which the vast majority of signals coming from the flaw detector is a rail noise. A signal is considered useful and is subject to further analysis if its amplitude is twice the corresponding noise threshold. The article is devoted to the problem of correcting threshold levels, taking into account the need to identify extensive surface defects of rails. An algorithm is proposed for finding the values of threshold levels of rail noise amplitudes with their subsequent correction in the case of a large number of useful signals from extensive defects. Examples of the algorithm’s operation on real eddy-current data are given.