RU2434222C2 - Apparatus for investigating kinematic viscosity of melts - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: apparatus for investigating kinematic viscosity of melts has a viscosimetric module in an evacuated or water-cooled chamber, along the axis of which a suspension system with a crucible is placed in the heating zone of an electric heater. The apparatus also has a suspension system accelerating unit, an accelerating unit switch, a mirror, a light source, a photodetector and a computer. The device also includes a visual and audio signalling unit, having at least one visual and one audio signalling device, a counter with a display. The input bus of the visual and audio signalling unit is connected to one of the computer ports. The input of the counter with a display and the computer are connected to the output bus of the visual and audio signalling unit, and the acceleration unit switch is also connected to one of the computer ports.

EFFECT: simplification and optimisation of the procedure of measuring viscosity, while cutting the measurement time and reducing wastes from melt components while maintaining reliability and accuracy of determining amplitude-time parameters of damping torsional vibrations of the crucible with the melt.

3 cl, 5 dwg

Description

The invention relates to physics and metallurgy, and in particular to devices used in research and laboratory work, and is used for signaling and measuring the physical parameters of melts; it is intended for non-contact measurement of the kinematic viscosity of metal melts, in particular high-temperature, by a non-stationary photometric method based on measuring the damping of torsional vibrations of a cylindrical crucible with a melt. An additional area of application is manufacturing processes.

Measurement of the physicochemical parameters of metallic liquids, melts and slags, in particular viscometry — determining the viscosity v of high-temperature melts in a volume of several cm ³ , allows you to clearly demonstrate the structure-sensitive characteristics of a liquid, conduct prognostic analysis of materials, and make recommendations for producing alloys with specified characteristics at industrial enterprises; in particular, polytherms of viscosity ν (versus temperature) make it possible to distinguish critical temperature points and hysteretic characteristics of heating-cooling. However, for high-temperature studies of metal melts, only a few methods for measuring the viscosity ν and, accordingly, devices for their implementation are used in practice. In particular, a device is known that is intended for university students to perform laboratory work, which uses a non-stationary non-contact photometric (based on measuring the trajectory of the light "bunny") method for determining the kinematic viscosity ν based on preliminary calculation of the logarithmic attenuation decrement δ. The determination of δ is made by measuring the amplitudes of exponentially decaying free vibrations A _i , periods T _i , time values t ₁ , durations of time segments τ _i , number n _{i of} torsional vibrations of a crucible with a melt:

In this case, use an arbitrary, suitable for a particular installation, number n _{i of} amplitudes A _{i of} damped oscillations to determine δ by measuring the amplitude-time parameters of the damping of torsional vibrations of a crucible with a melt suspended on an elastic thread in the heating zone of a vacuum furnace - see V. Vyukhin. . et al. - “Study of the kinematic viscosity of melts” - guidelines for laboratory work in physics, Ekaterinburg, GOU VPO Ural State Technical University - UPI, 2006, p.5 - analogue.

The disadvantage of this device is the complexity of each experiment due to the dependence of the procedure on the parameters of a particular equipment, the randomness and subjectivity of the choice of parameters of damped oscillations for determining δ: for example, n _{i is} taken equal from 4 ... 5 to 8 ... 11 according to the recommendations of different experimenters - see S.I. Filippov et al. “Physico-chemical methods for the study of metallurgical processes”, Moscow: Metallurgy, 1968, p. 246. In this case, the arbitrarily and subjectively selected last measured amplitude A _ni can be of any value and vary from experience to experience with one melt, and for different melts. Therefore, it is necessary to carry out lengthy, sometimes multivariate measurements with additional statistical processing of the results. The device does not provide a typical procedure for measuring attenuation parameters, which makes it difficult to compare the results of various experiments. The device does not automatically select the parameters of the torsional vibrations of the crucible with the melt at characteristic important points of the measurement procedure, as well as the allocation and indication of these moments. Hence the subjective temporal dynamics of the experiments: the researcher manually shuts down acceleration, i.e. forced twisting of the elastic thread, the beginning of free damped torsional vibrations and the researcher's choice of the initial moment of measurement of parameters (t _o = 0, A _i = A _o ), the end of the measurement of parameters, the beginning of a new measurement cycle, i.e. the beginning of a new forced twisting of the elastic thread. Even for a qualified researcher with experience, continuous monitoring and correction of the course of experiments is required. For unskilled personnel, for example, students performing this work as a laboratory, the lack of an unambiguous indication of the above points is fraught, firstly, with a partial or complete lack of understanding of the dynamics of the melt viscometry procedure; secondly, the danger of incorrect actions and the occurrence of emergency situations, up to the failure of the study; thirdly, the receipt of a false or unreliable final result of the study. An automated installation in this case is unsuitable - see above - Vyuhin V.V. and others ..., p.13, but the semi-automatic mode does not guarantee against errors and gross blunders in the experiment.

A device is known for non-contact viscosity measurement of high-temperature metal melts - see patent for utility model of the Russian Federation No. 69249, G01 / N 11/16, publ. 12/10/2007, bull. No. 34 - a prototype containing a viscometric module in a vacuum and water-cooled cylindrical chamber, along the axis of which, in the heating zone of the electric heater, a suspension system with a crucible, a suspension system acceleration unit at a predetermined angle to start torsional vibrations, an acceleration unit switch, a mirror, a light source , photodetector, prototype computer.

The disadvantage of this device, as above, is that there is a subjective and there is no objective and unambiguous for the researcher indication and evaluation of a number of points in the experiment procedure, because there is no automatic selection of the parameters of torsional vibrations of a crucible with a melt at characteristic important points of the measurement procedure, for example, turning off acceleration - forcibly twisting an elastic thread, starting free torsional vibrations, starting measuring the parameters of damped vibrations, finishing measuring these parameters, and starting a new measurement cycle. The above does not allow to simplify and, in some cases, accelerate the experiment, requires increased attention continuously in the research process and does not allow independent experiments to be carried out by unskilled personnel, for example, students.

The objective of the invention is to simplify the procedure for determining the kinematic viscosity of high-temperature metal melts by means of the proposed device for studying the kinematic viscosity of melts, to enable unskilled personnel, such as students, to reduce the measurement time and reduce the fumes of the components of the melts in most experiments, as well as to ensure the reliability and comparability of the procedure and experimental results.

To solve this problem, a device for studying the kinematic viscosity of melts is proposed.

A device for studying the kinematic viscosity of melts containing a viscometric module in a vacuum and water-cooled chamber, along the axis of which, in the heating zone of the electric heater, a suspension system with a crucible, an acceleration unit of the suspension system, an acceleration unit switch, a mirror, a light source, a photodetector, a computer , introduced: a visual and audible alarm unit comprising at least one visual and one audible signaling devices; a counter with an indicator, with the following connections: the input bus of the visual and audible alarm unit is connected to one of the computer ports, the input of the counter with an indicator and a computer are connected to the output bus of the visual and audible alarm unit, the acceleration unit switch is connected to one of the computer ports.

In addition, the visual and audible signaling unit is made in the form of at least a dual-band optical and dual-frequency audible signaling device with adjustable parameters, for example, an alarm time.

In addition, the acceleration block switch is made in the form of an electronic key.

Distinctive features of the proposed technical solution provide a simplification of the procedure for determining the kinematic viscosity of high-temperature metal melts by means of the proposed device for studying the kinematic viscosity of melts, providing the opportunity for unskilled personnel, for example, students, to reduce the measurement time and reduce the fumes of the components of the melts in most experiments, as well as ensuring the reliability and comparability of the procedure and the results of the expert rimentov.

The invention is illustrated by drawings:

figure 1. Block diagram of a measuring complex;

figure 2. Oscillogram of the trajectory of the reflected light beam corresponding to torsional vibrations of the crucible with the melt;

figure 3. Experimental data of damped torsional vibrations and measurement errors in the form of standard deviations σ ² : a - pure electrical copper, t ° = 1150 ° C; b - high alloy cast iron, t ° = 1350 ° C;

figure 4. Experimental data of damped torsional vibrations and measurement errors in the form of coefficient of variation C _v ; a - pure electrical copper, t ° = 1150 ° C; b - high alloy cast iron, t ° = 1350 ° C;

figure 5. Algorithm for controlling the measurement procedure and signaling.

A device for studying the kinematic viscosity of melts contains: a crucible 1 with a charge placed in the center of the high-temperature zone of the furnace 2 with a molybdenum cylindrical electric heater 3 and suspended on an elastic thread 4, an acceleration unit 5 that rotates the suspension system at a given angle to start torsional vibrations, mirror 6 , light source 7, photodetector 8, computer 9, switch 10 of the acceleration unit 5, visual and audible alarm unit 11, counter with indicator 12, visual and audible alarm unit 11 t, at least one visual 13 and one sound 14 signaling devices, the control bus 15 of the switch 10 of the acceleration unit 5, the input bus 16 of the block visual and audible alarm 11.

The device is made on the following elements: crucible 1 is made of high-temperature beryllium ceramics, a molybdenum cylindrical electric heater 3 is made of a sheet with a thickness of a few tenths of a millimeter, an elastic filament 4 is nichrome, a length of about 650 and a diameter of 0.08 mm, the acceleration unit 5 is made in the form of an electric motor direct current (not shown in the diagram) with a power consumption of approximately 70 mW connected to a low-voltage power supply (not shown in the diagram), mirror 6 has an area of 1 cm ² , light source 7 is an ultra-bright LED L7113SEC-H of firms Kingbright s - see catalog Kingbright, 2005-2006, photodetector 8 contains integrated circuits - optosensors TSL250 manufactured by TAOS (or their analogues ORT101, S4810 from other companies) - see catalog ELFA - 55, 2007, p. 812, located on a fixed distance +/- L from each other symmetrically with respect to the center of the double-sided optical scale in the equilibrium position and IR solid state PVG612 opto-couplers, personal computer 9 - PC level no worse than Р-2, acceleration block 10 switch assembled on the key CMOS IC КТ561КТ3, in parallel with which it is turned on manually operated emergency toggle switch - a switch (not shown in the diagram), a visual and audible alarm unit 11 contains: CMOS IC KT561KT3 keys, a single vibrator based on CMOS IC KT561LE5, visual 13 signaling devices — LEDs of different optical ranges (colors) of the AL307 series, audio signaling device 14 — standard autogenerators — multivibrators on transistors KT315, loaded on a low-power dynamic head, for example, 0.25GD; option - visual 13 and sound 14 signaling devices of the visual and sound signaling unit 11 can be made in the form of one multi-frequency sound generator and one multi-color - for example, a two-color LED; counter with indicator 12 - serial frequency meter Ф5035.

A device for studying the kinematic viscosity of melts works as follows.

The crucible 1, containing a volume of the investigated metal melt of about 3 cm ³ and suspended on an elastic filament 4, is placed in the center of the high-temperature zone of the furnace 2, heated to the required temperature by a coaxial cylindrical molybdenum electric heater 3, providing an isothermal zone and turned on continuously throughout the experiment, after which from the power supply unit (not shown in the diagram), by means of the switch 10, the supply voltage is applied to the acceleration unit 5, which creates torsional vibrations 17. The switch 10 is switched on lyayut by feeding on the control bus 15 signals from a computer 9. The signal for shut down procedures and acceleration, respectively, to the top of the measurement cycle is established to achieve the maximum, for a given installation and this experiment, the amplitude of torsional vibrations of A _o and the minimum time interval τ _i. At the same time, via the control bus 15, the same signal from the computer 9 through the corresponding key stages includes the corresponding visual 13 and sound 14 signaling devices of the visual and sound signaling unit 11. The signaling devices 13 and 14 can be modulated, for example, using a single vibrator (S) with a pulse duration, for example, 1 second. Such a short sound signal of a multivibrator detector 14 with a frequency of F ₁ = 400 ... 600 Hz and the simultaneous glow, for example, in the green range, of the LED detector 13, for a duration of, for example, 1 s, serve as a signal to the experimenter about the beginning of the measurement procedure. The oscillation path 17 is monitored using a mirror 6 fixed on the elastic thread 4 of the suspension system with the crucible 1, while the path of the light beam from the light source 7, reflected from the mirror 6, reproduces the torsional vibration curve 17. At some point in time t ₁ reflected beam falls on one of the photosensors of the photodetector unit 8, the output photodetector 8 appears a corresponding signal U _1, which through the output line photodetecting device 8 is introduced in the computer 9 as a starter for performing one of fragm ntov computer program - calculating τ _i time slots required for further calculation of parameters logarithmic decrement δ of known formulas. After some time at time t _{2, the} light beam reflected from the mirror 6 illuminates another photosensor of the photodetector 8, the corresponding signal U ₂ appears at the output of the photodetector 8, which, like the first signal U ₁ , is entered into the computer 9 as a stop signal of this fragment of a computer program - calculation of time intervals τ _i .

Note that the oscillation period, for example, T = 4.2 s, is unambiguously associated with the number of oscillations n _i for each particular experiment in this installation, with a time of complete attenuation of the oscillations up to several tens of minutes for each temperature measurement point. On the oscillatory trajectory 17 in FIG. 2, amplitude extrema are noted, starting from A _o to A _i , the times t ₁ , t _{2 of the} passage of the linear portion ΔA of the oscillatory trajectory 17 by the reflected light beam through the photosensor of the photodetector 8.

Starting from the moment the acceleration unit 5 is turned off, which is accompanied by the above-described visual and audible signaling procedure carried out by the visual and audible signaling unit 11, a cycle of measuring the amplitude-time parameters of damped torsional vibrations (t _o = 0, A _i = A _o ) begins. The leading edge of the signal U ₁ launches a computer program for calculating δ at time intervals τ _i in accordance with the formula [1]. In the process of measurement, a characteristic important moment of the measurement procedure is distinguished, when the current amplitude of the oscillation decreases e times: A _i = A ₀ / e = A _e , respectively, the current time interval increases e times: τ _i = e × τ ₀ = τ _e , and the number of oscillations becomes equal to n _i = n _e . Moreover, the formula [1] is simplified, in the calculations it becomes enough to use only the number of oscillations n _e . A computer program for calculating δ at the end of the time interval τ ₁ = τ _e , when the corresponding signal U _2e appears, the trailing edge of which for computer 9 is a stop signal of a fragment of a computer program - calculating time intervals τ _i , includes a visual and audible alarm unit 11, feeding on its input bus 16, the corresponding signal. This signal includes, through other key stages, other visual 13 and sound 14 signaling devices of the visual and sound signaling unit 11, which differ in sound frequency, for example, F ₂ = 2 ... 3 kHz ≠ F ₁ , and the glow color, for example, red. Alternatively, visual 13 and sound 14 signaling devices of the visual and sound signaling unit 11 can be made in the form of one multi-frequency sound generator and one two-color LED.

Signals from the visual signaling device 13 of the visual and audible signaling unit 11 through diode dividing chains (not shown in the diagram) are fed as start (from one LED) and stop (from another LED) signals to computer 9 and to the counter input with indicator 12, which indicates number n _i = n _e . Such an indication of the number of vibrations, together with an audible and visual alarm, visually reflects the course of the experiment and its main critical points, simplifies and facilitates both understanding the course of the study and making decisions by the experimenter, if necessary.

The visual and audible alarm unit 11, as well as the counter with indicator 12, can be implemented in virtual form by means of computer 9, while the display of computer 9 serves, among other things, as a visual signaling device 13 and indicator of virtual counter 12, and the sound signal is reproduced by acoustic emitters computer or monitor.

When implementing in virtual form the visual and audible alarm unit 11, as well as the counter with indicator 12, in computer 9, the experimental data of the damped torsional vibrations of the crucible 1 with melts are obtained, shown in FIG. 3: a - pure electrical copper, t ° = 1150 ° C; b - high alloy cast iron, t ° = 1350 ° C.

The corresponding equations of the exponentials of damped torsional vibrations 18 for time t and the number n of vibrations, standard deviations σ ² 19 are calculated, the amplitude point A _i = A _o / e = A _e 20 and σ ² 21 for it are marked. The conditional amplitude Y _i , determined by the time the light beam travels on the linear portion ΔA of the oscillatory path 17 through the optosensors of the photodetector 8: Y _i ~ 1 / Δt = 1 / (t ₁ -t ₂ ), is uniquely associated with the amplitudes A _i . The time Δt is measured in proportion to the number of clock cycles of the central processor of computer 9, having, for example, a clock frequency f = 166 MHz. Similar data are shown in Fig. 4 and differ in that, instead of the standard deviation σ ² 19, the coefficient of variation C _v = (√σ / A _average ) 100% 22, i.e. relative error in%, taking into account the standard deviation σ ² 19, including for A _e 23. The data of Figs. 3, 4 demonstrate that, on the one hand, the use of the first 5 ... 10 amplitudes A _i as A _n causes significant errors (scatter of both σ ² 19 and C _v 22), which corresponds to the data of some researchers (see the above S. I. Filippov et al. “Physicochemical methods for studying metallurgical processes”, M .: Metallurgy, 1968, p. 246). On the other hand, the use of the “tail” of an exponent requires unreasonably large time expenditures, at which burnout of the melt components is inevitable, and the accuracy increases slightly. In addition, there is a danger of entering the nonlinear region of amplitudes, where the linear segment ΔА of the cosine wave 17 (see Fig. 2) degenerates into the cosine wave itself, after which it is impossible to evaluate the reliability and accuracy of the results. Therefore, the alarm at an important point A _e 20, indicating the end of the measurements (second signal), is the optimal solution for measuring the necessary and sufficient number of oscillations n = n _e , allowing to obtain a reasonable, reliable and accurate result (C _v 23 is 0.5 ... 0 , 7%) instead of the subjective long, complex and not always reasonable measure different amounts of amplitudes a _i 18. The use of signaling at a given point can reasonably be automated, at least measuring cycle time and amplitude parameters cool damped nyh oscillation from the time of acceleration OFF unit 5 (first signal).

The control algorithm of the measurement procedure and alarm is shown in figure 5.

The technical result of the proposed technical solution is to increase the level of automation, simplify and, in most cases, accelerate experiments while reducing the melt burn, while maintaining the reliability of determining the amplitude-time attenuation parameters of the torsional vibrations of the crucible with the melt when measuring the kinematic viscosity of metal melts using the proposed device. EFFECT: reduction of the researcher's labor intensity, expansion of the scope of the device, in particular, the ability to work with the device to unskilled personnel, such as students.

Claims (3)

1. A device for studying the kinematic viscosity of melts, containing a viscometer module in a vacuum and water-cooled chamber, along the axis of which, in the heating zone of the electric heater, a suspension system with a crucible, an acceleration unit of the suspension system, an acceleration unit switch, a mirror, a light source, a photodetector, a computer, characterized in that a visual and audible alarm unit is introduced into it, comprising at least one visual and one audible alarms, a counter with an indicator, an input bus the visual and audible alarm unit is connected to one of the computer ports, the counter input with an indicator and the computer are connected to the output bus of the visual and audible alarm unit, and the acceleration unit circuit breaker is also connected to one of the computer ports. 2. The device according to claim 1, characterized in that the visual and audible signaling unit is made in the form of at least a dual-band optical and dual-frequency sound signaling device with adjustable parameters, for example, signaling time. 3. The device according to claim 1, characterized in that the accelerator block switch is made in the form of an electronic key.

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