Autobiography & resume 
Solomichev Roman
Faculty of Computer Information Technologies and Automation
Cathedra of electronic technics
Speciality: Electronic systems
Abstract on the topic of master's work:
Justification and researching the electronic control system's block diagram of the under surface layer of steel rolling rolls
Scientific adviser: Zori Anatolij Anatolijovich, prof.
1. Introduction
At this time in the mining and metallurgical industry relevant issue is to monitor the technical condition of the rolls to reduce the likelihood of premature failure.
Rolls rolling mill 2300 hot rolling mill are subjected to significant thermal effects (до 500 °С) and loads (pressure of about 3 tons, etc.) in a continuous mode of rolling steel sheets. As a result of aggressive environment surface roll coming into disrepair during a certain period of time: there are fatigue cracks that develop due to the anodic processes (chemical dissolution of metal) and cathode (eg, separation of hydrogen, which diffuses into the material and cause destruction under the influence of temperature and load).
There is also has its own scale degradation of the working body: from 1 to 4: the unit begins with the birth of a surface layer of the fatigue cracks that have not yet opened outward, and the fourth stage, the most dangerous, when a crack opened on the surface of the rolls and the products have a marriage (furrows and lines of on the surface of rolled products, imperfect smoothness).
Currently in production, no technical means are not used for automatic monitoring of the surface of the rolls. Verification is purely visual: employee watching that go out from under the rolls and then had to ostyvshimi rolled sheets and checks for marriage, and surface defects rolls are installed as a fact.2. Purpose and objectives
Objective: To substantiate the structure of the electronic monitoring of the surface layer of steel mill rolls, in use, explore and simulate the effect of disturbing factors on the characteristics and parameters of multichannel defectoscopic complex automated control of high-rollers on the contactless electromagnetic-acoustic (EMA) method.
Achieving this goal provides the following tasks:
investigate the dependence of the attenuation of ultrasonic oscillations (USO) on the size of grains of metal rolls with changes in temperature;
investigate attenuation and distortion of the ultrasonic in the air;
calculate the generator and the receiver to select EMA oscillations;
investigate the effect of the angle of divergence on the amplitude information signal and calculate the acoustic field transducer;
determine the resolving power, sensitivity and metrological characteristics of the converter;
up method of monitoring to detect defects in the minimum.
3. Scientific novelty
Ready-made tools and assessment rolls techniques, which have facilitated the identification of surface cracks, measure their depth, to help determine the places of mechanical stresses concentration, to measure the hardness of work surfaces, to investigate the temperature regimes of the rolls in the process of exploitation, in the workshop environment, instrument-making industry in Ukraine is not performed. There are no regulations that define their requirements, with respect to steel-rolling equipment.
4. Choice of nondestructive testing (NDT)
According to the state standard 18353-73 nondestructive testing is classified into types: acoustic, magnetic, optical, radiation, radio wave, thermal, electrical, electromagnetic and electromagnetic-acoustic.
The method of control of steel mill rolls should be a non-contact, to ensure recognition of internal defects - cracks in the stage of nucleation, and surface, if the internal cracks have opened on the surface.
The easiest way to control the production - visual, the essence of which lies in the fact that the technical staff in a timely manner noticed in the finished product - Plates defects (fissures and a relief pattern) of the crack on the rolls. After this, production is suspended for an indefinite period for the replacement of the rolls of new, which is then calibrated and improving, and damaged rental excluded. Technically, an employee may replace an automated system. The visual method has many shortcomings and does not satisfy us.
The radiation method is based on the interaction of penetrating radiation in the object of control. It is more suitable for determining the internal material impurities and surface defects is not recognized and is not cheap.
Radiofrequency method based on registration of changes in the parameters of electromagnetic waves that interact with the object of control. It is mainly used to control the structure, geometry, dielectrics, and partly in the measurements of the thickness of metal products.
Thermal methods in our case did not apply because the area of monitoring the temperature is sufficiently large, and the thermal contrast of the controlled object will not be recognized.
A purely acoustic methods (ultrasonic, acousto-emission and other) or magnetic (powder, eddy current, etc.) can not be used alone and require conducting acoustic (immersion) environment.
Of all the above methods is most suitable mixed-purpose electromagnetic-acoustic (EMA). EMA method is based on three effects of the interaction of electromagnetic fields with supervision object (SO): magnetostriction, magnetic and electrodynamic interaction.
Electromagnetic interaction is excited in the conductive material to eddy currents, which interact with the static magnetic field and cause fluctuations in the "electron gas", and this in turn leads to the excitation of atomic vibrations, ie crystal lattice of the material (there are mechanical stress, which subsequently leads to the appearance of elastic acoustic oscillations).
With the help of EMA transducers can excite different waves: horizontal, vertical polarization, the longitudinal, transverse, Lamb, Rayleigh, etc. The most acceptable in our case are inclined shear waves of horizontal polarization, due to its minimal damping coefficient, diffraction, refraction in the structure of the metal. Waves of this type can be excited by a spatially periodic system of magnets, as shown in Figure 1.
Figure 1 - Excitation of acoustic waves EMA method
The method consists in the fact that irradiates the object of control of Rayleigh waves, register transformed defect ultrasound: an object is placed upon the control of the magnetic field and record the scattered defect magnetic flux, modulated ultrasound wave, the amplitude and polarization of the transformed ultrasonic wave. As the variable component of the scattered flux is judged on the depth, orientation and the disclosure of the defect.
Technically, this principle is being implemented as follows: between the magnets and the OC have conductors paramennym shock I (on Figure 1 shows one of the conductors). The interaction of the induced current I' with the force lines of magnetic field B gives rise to elastic forces directed perpendicular to the plane of the figure (σ). This is required to excite the inclined shear waves polarized perpendicular to the plane of refraction.
The general rule that should guide the design of EMA-converter for a certain type of wave excitation lies in the fact that the resulting electromagnetic interaction of mechanical stresses σ proportional to the vector product in the product induced by AC I' on the magnetic induction B:σ ~ I' × B
The distance between the like poles of magnets m chosen from the condition:
m = λ / sin(α),
where λ -length of the transverse wave, α - USO proliferation angle.
A major merit EMA-method is the possibility of using high temperatures (to 1300°С), as well as the fact that he is SO with the contactless.
EMA-transducers now obtain the greatest spread the word as a means of contactless radiation and reception of ultrasonic waves. This is due to their relatively high conversion efficiency compared to other methods of contactless excitation of acoustic waves (at frequencies commonly used in flaw: 1-5 MHz), and their broadband, to initiate a wave of various types, the weak dependence of the transformation from surface irregularities (verification can be produce in the presence of scale on the rolls), applicability of EMA-transducers to control not only cold but also hot items.
Disadvantages should be considered cumbersome converters because of the need for strong bias and low conversion efficiency, but because of all the shortcomings, this method is the best in the context of this topic.
A device that implements this method, contains electromagnetic acoustic transducers (emission - shaper UT and reception - sensors), the amplifier unit of informative parameters, coupled with the flaw, and block the decision. Effect: improving the sensitivity and reliability of control.
Figure 2 - Block diagram of electronic system
On the structural diagram used such blocks: channel sensors 1..N - piezoelectric ultrasonic transmitters; probe of channel temperature compensation; transmitters parameter of an electrical circuit - an electrical signal (Tr); Analog Transmitters (ATr), to convert the measured acoustic signals in a unified signal current or voltage; Link (L); Matching Amplifier (MA); Analog Multiplexer (AMUX); Sample and Hold (S&H); Analog-Digilal Converter (ADC); Microprocessor Unit (MPU), providing data processing, decision-making and control signals Actuating Signal AS1..AS3 respectively МАС, ПВЗ, АЦП; random-access memory (RAM) for storage; Screen Display (SD).
The process of rolled steel sheet and control of the rolls for the presence of developing defects is shown in Figure 3.
Figure 3 - The control process steel rolling rolls. Flash animation, 145 frames, looped repetition, 35Kb
There is on Figure 3 numerals denote parts block the formation of USO: 1 - the system of permanent magnets with the applied voltage U1; 2 - conductors with alternating current I2 and the applied voltage U2; 3 - sensor (piezoelectric ultrasonic transducer).
In the normal state of the rollers, when missing from fatigue cracks generated ultrasonic vibrations are dispersed in the structure of the metal, not focusing on the sensor, which shows waveform without perturbation block display.
When does the birth defects in the surface layer of rolls, generated by ultrasonic reflected from the cracks and get on the acoustic transducer, the output signal is amplified, processed and displayed on the screen. Depending on what set the detection threshold, the intensity of the alarm can be changed with a corresponding development of defects: an increase in the volume of cracks amplitude of acoustic signals from the sensor, increases substantially. Thus, judging on the state of the residual life of the object control.5. Conclusion
This study formulates the goal and objectives of research, which argumantiruyutsya real business needs in the system diagnosis, which are caused by increased efficiency and productivity of equipment. When you install additional equipment, much reduce the likelihood of premature failure of the working bodies - rollers, reduced to a minimum yield of defective rolling. The monitoring process would take place without contact with a certain interval of time when using electromagnetoelasticity-acoustic method, which will reduce the downtime of the camp at technological break.
Further calculations and studies will provide the numerical characteristics and parameters of the optimal system of control of the surface layer of steel mill rolls, the resolving power of scanning, the number of converters that will fully cover the maximum amount of the working surface of rolls.
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© DonNTU, Colomichev Roman, 2010