RU2011977C1 - Method of and device for contactless measurement of thermophysical characteristics of materials - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: method of contactless measurement of material thermophysical characteristics involves action of dot-cycle moving source of definite power on body surface, measurement of excess critical temperature of surface being heated at points of body surface, measurement of distance between temperature check point and center of source heating spot, recording of relative position of heat supply points, and temperature measurement; data obtained are used in determining unknown values; temperature check point is placed in center of heating spot; temperature check point is displaced from heating spot along source movement line towards lagging side through preset distance and in the action distance-integral excess critical temperature is measured on movement between heating spot and preset position of check point; excess temperature is determined in preset position of check point, the latter is placed in center of heating spot, and then it is removed along arbitrarily selected line towards lag from source. Contactless measurement device has concentrated heat energy sources secured above surface of body under test, and heat sinks focussed onto body surface, energy source and heat sink moving gear that moves them relative to specimen under test; in addition it has four electronic switches, voltage-to-frequency converter, reversing counter, two analog-to- digital converters, central processor unit, input/output unit, keyboard control console, inverter, motor power polarity switch, two potentiometers with regulated power supply, reference-voltage dropping unit, two heat-sink moving mechanisms, output unit, comparator. EFFECT: improved measurement accuracy in nondestructive tests of materials and finished products. 2 cl, 2 dwg, 1 tbl

Description

 The invention relates to measuring equipment and can be used in non-destructive quality control systems for materials and finished products made of them, used in engineering, aviation, radio engineering, construction and other industries.

 A known method for determining the thermal conductivity of materials [1], including heating the surface of the test sample and the reference with a moving point source of energy, measuring the initial temperatures of the test and reference samples with a temperature sensor moving with a fixed lag from the energy source, as well as determining the maximum excess temperatures of the samples with which calculate the desired value.

 The disadvantage of this method is the inability to take into account the determined thermophysical characteristics of heat loss to the environment in the measurement results, which significantly limits the accuracy and reliability of the received measurement information.

 Also known is a device [2] for determining the thermal conductivity of materials, comprising a movable platform and a platform drive connected in series, as well as a concentrated source of thermal energy, two radiometers, a reference sample mounted on a mobile platform, a recorder and a drive control unit, the radiometers being connected to the corresponding register inputs .

 A disadvantage of the known device is the narrow range of its functionality, which does not allow for a comprehensive determination of the thermophysical characteristics of materials, as well as limitations on the accuracy and reliability of the obtained measurement information due to the lack of the possibility of introducing amendments to the measurement result for thermal energy loss into the environment.

 The prototype adopted a method of non-contact control of the thermophysical characteristics of materials [3], in which the surface of the test body is affected by a point heat source moving in a straight line at a constant speed, excessive temperatures are recorded at surface points with some lag on the same line and parallel to it and by the magnitude of excess temperatures, the desired thermophysical characteristics are calculated.

 The disadvantage of this method is the low accuracy of determining the desired characteristics, since the experiment does not take into account the heat loss from the heated surface of the materials into the environment, which leads to an additional error in the measurement results.

 The prototype is a device for determining the thermophysical characteristics of materials [4], containing a movable platform and a platform drive connected in series, as well as a concentrated source of thermal energy, four radiometers that are connected to the corresponding inputs of the recorder, and two reference samples mounted on a mobile platform. The device further comprises a drive control unit.

 The disadvantage of this device is its low accuracy, since it does not allow to take into account and introduce corrections as a result of measurements of heat losses to the environment.

 The aim of the invention is to improve the accuracy of measuring the thermophysical characteristics of materials.

λ =

, где λ, а - коэффициенты тепло- и температуропроводности [Вт/м˙к] ; [м²/с] ; R₁, R_x1, R_x2 - соответственно заданное и найденные расстояния между центром пятна нагрева и точкой контроля температуры [м] ; T₁(R₁), T₂(R_x1) и T₃(R_x2)- избыточные температуры в точках соответственно на расстояниях R₁, R_x1 и R_x2 от центра пятна нагрева при мощности источника q₁ и q₂ [^oC] ; V - скорость движения источника и термоприемника относительно исследуемого тела [м/с] ; Х^I - расстояние между центром пятна нагрева и проекцией точки, расположенной на расстоянии R_x1, на линию движения источника энергии [м] .The goal is achieved by the fact that in the method of non-contact measurement of the thermophysical characteristics of materials, consisting in the thermal effect on the surface of the body by a point moving source of a certain power, measuring the excess temperature limit of the heated surface at points on the surface of the body moving with the speed of the source along its line of motion and in parallel to it , changing the distance between the temperature control point and the center of the source heating spot, recording the relative position of the heat supply points and temperature grazing, place the temperature control point in the center of the heating spot, shift the temperature control point from the heating spot along the line of movement of the source to the lag side by a predetermined distance, while measuring the distance-integrated value of the excess temperature limit on the segment of movement from the heating spot to the specified position of the point control, determine the excess temperature in a given position of the control point, place the control point in the center of the heating spot, and then remove it along an arbitrarily selected straight line and in the direction of lagging from the source by a distance at which the distance-integrated value of the excess temperature will be equal to the value of the integral temperature obtained when the control point moves along the source line for a given distance, the control point is moved to the center of the heating spot and the power of the energy source is changed by a certain amount , move the control point from the center of the heating spot along the line of movement of the source in the direction of lagging behind it by a distance at which the distance-integral value of the excess internal temperature would be equal to the value of the integral temperature during the motion of the source line with the initial capacity, and the desired thermal characteristics are determined from the following relationships:
a =

λ =

where λ, а are the coefficients of heat and thermal diffusivity [W / m˙k]; [m ² / s]; R ₁ , R _x1 , R _x2 , respectively, the given and found distances between the center of the heating spot and the temperature control point [m]; T ₁ (R ₁ ), T ₂ (R _x1 ) and T ₃ (R _x2 ) are the excess temperatures at the points, respectively, at distances R ₁ , R _x1 and R _x2 from the center of the heating spot at the source power q ₁ and q ₂ [ ^o C]; V is the speed of movement of the source and thermal receiver relative to the test body [m / s]; X ^I - the distance between the center of the heating spot and the projection of the point located at a distance R _x1 , on the line of motion of the energy source [m].

 In the device according to this method, containing a concentrated source of thermal energy and a thermal detector fixed above the surface of the test body, focused on the surface of the body, the mechanism for moving the energy source and thermal detector relative to the test sample, additionally includes four electronic keys, a voltage to frequency converter, a reversible counter, two analog -digital converter, central processor, input-output unit, keypad, inverter, circuit polarity switch engine power supply, two potentiometers with a stabilized power source, a reference voltage setting unit, two mechanisms for moving the thermal receiver relative to the heat energy source, an output unit, the output of the thermal receiver being connected to the information inputs of the first and second electronic keys, and the output of the first key connected to the input of the voltage converter frequency, the output of which is in turn connected to the information input of the reverse counter, the output of the second electronic key through the first analog-to-digital the converter is connected to the first input of the central processor, the second input of which is connected to the keypad via the input-output device, one of the outputs of the control panel is connected to the control input of the third key, the information input of which is connected to the flow rate of the first potentiometer, and the output to the first input a comparator, the second input of which is connected to the output of the reference voltage setting unit and the input of the reference voltage setting unit is connected to the control panel, in addition, the output of the comparator is connected n to the control input of the first electronic switch and the input of the inverter, the output of which is connected to the control unit of the second electronic switch, the control input of which is connected to the output of the reverse counter, and the output of the key through the second analog-to-digital converter is connected to the third input of the central processor, the rechord of the first potentiometer is connected also with the control circuit of the magnetic starter of the reversing motor, the power circuit of which is connected to the motor power supply through the polarity switch, and the motor shaft I am connected to a mechanism for moving the thermal receiver relative to a point source of energy in the direction of movement of the source, and also to a mechanism for moving the thermal receiver in a direction perpendicular to the direction of the source, in addition, the potentiometers are connected to a stabilized voltage source, and the reochord of the first potentiometer is kinematically connected to the mechanism for moving the thermal receiver in the direction movement of the heat source, the rechord of the second potentiometer is connected to the mechanism for moving the thermal receiver in to the perpendicular to the direction of movement of the source, the rechords of two potentiometers are connected respectively to the first and second information inputs of the fourth electronic key, the output of which is connected to the input of the second analog-to-digital converter, the output of the reversible counter is connected to the control inputs of the second and fourth electronic keys, as well as to the circuit control of the magnetic starter, in addition, the output of the comparator is connected to the magnetic starter and the mechanism for moving the energy source and thermal receiver relative relative to the product under study, and the control unit is connected to the reversing motor power supply polarity switching unit, a magnetic starter, a source and thermal detector moving mechanism, and an energy source power supply unit, the information output of the central processor through the output unit is connected to the indicator and information inputs of the reverse counter.

 When analyzing known technical solutions for methods and devices of non-destructive testing of the thermophysical characteristics of materials, no solutions were found that have significant features similar to the distinguishing features of the proposed method and device.

 Based on the analysis, we can conclude that the claimed technical solution has significant differences.

The presence of a set of essential features, namely the measurement of excess temperatures at given and found accordingly control points T ₁ (R ₁ ). T ₂ (R _x1 ), T ₃ (R _x2 ), changing the power of the energy source by a certain amount, moving the control point along the line of movement of the energy source by a distance at which the distance-integrated value of the excess temperature will be equal to the temperature value when moving along the source line with initial power, as well as the introduction to the device of an additional four electronic keys of a voltage-to-frequency converter, a reverse counter, a central processor, an input-output unit, a keypad, an inventory , The polarity of the power switch circuit, the motor, the two displacement termopriemnika, the output unit increases the precision mechanisms, which indicates the achievement of the purpose of the invention.

The essence of the method is as follows. A point source of thermal energy and a thermal detector, focused at a point on the surface exposed to heat, are placed above the test product. They turn on the energy source and begin moving it and the thermal receiver over the test article at a constant speed. Then, the control point of the limiting excess temperature is gradually shifted from the heating spot along the line of movement of the source to the lagging direction until a predetermined distance R ₁ between the source and the thermal receiver is reached, while measuring the distance-integrated value of the excess temperature S ₁ (R) on the segment of the line of motion from the heating spot to the point of control. Measure the excess temperature at point R ₁ . Further, by moving the temperature control point to the center of the heating spot, the points of excess temperature control are gradually removed from the heating spot in the direction of lagging from the source along an arbitrary chosen straight line until the value of the excess temperature controlled by the distance of movement becomes equal to S ₁ (R ) (see Fig. 1), i.e., S ₁ (R) = S ₂ (R _x1 ). The found value of the distance R _x1 and the value of the excess temperature T ₂ (R _x1 ) are measured at this distance of the control point from the center of the heating spot. Then, by moving the temperature control point to the center of the heating spot and changing the source power by a certain amount, the excess temperature control point is shifted from the heating spot along the line of movement of the source in the direction of lagging from it until the temperature value controlled by the distance of movement becomes equal to the integral values of S ₁ (R ₁ ) or S ₂ (R _x1 ) (see Fig. 1), i.e. S ₁ (R ₁ ) = S ₃ (R _x2 ). The found value of the distance R _x2 and the value of the excess temperature are measured at this distance of the control point from the center of the heating spot, and the desired thermophysical characteristics are determined by the dependences obtained on the basis of the following considerations.

, (1) где q - мощность источника [Вт] ;

- коэффициент теплопроводности изделия [Вт/м˙К] ; R - расстояние между центром пятна нагрева и точкой измерения температуры [м] .It is known that when the surface of a body semi-infinite in heat terms is heated by a moving source of point energy, the excess limit temperature of the surface of this body at points moving after the source along its line of motion at a speed equal to the speed of movement of the energy source, determined by the dependence
T _t (R) =

, (1) where q is the source power [W];

- coefficient of thermal conductivity of the product [W / m˙K]; R is the distance between the center of the heating spot and the temperature measuring point [m].

, (2) где Δq_пот - потери тепловой мощности в окружающую среду за счет конвективного и лучистого теплообмена.Since the surface of the investigated product during the experiment is not thermally insulated from the environment, then after applying the heat, part of the heat from the heated surface of the product will be removed due to convective and radiant heat transfer to the environment. Therefore, the measured value of the excess limit temperature at a point moving after the source along the line of its movement and lagging behind it by a distance R ₁ will be determined by the dependence
T ₁ (R ₁ ) =

, (2) where Δq _sweat is the loss of thermal power to the environment due to convective and radiant heat transfer.

From the theory of heat conduction it is known (see, for example, Lykov A.V. Theory of heat conduction // Higher school, 1967) that the heat flux during convective and radiant heat transfer between the surface of a heated body and the environment is determined by the expression
q = α [T _t (R) - T _c ], (3) where α = α _к + α _beam is the total heat transfer coefficient [W / m ² K];
α _to - convective heat transfer coefficient; α _beam is the coefficient of radiant heat transfer; T _with - ambient temperature.

[T₁(R)-T_с] dR= S₁(R) (4) Чтобы потери энергии в окружающую среду при мощности источника q₁ были бы равны потерям Δq₁. экспериментально находят такое расстояние R_x1между точкой контроля избыточной температуры и пятна нагрева, при котором
Δq₂= α

[T₂(R)-T_с] dR= S₂(R

)= S₁(R) (5) При нагреве поверхности исследуемого тела подвижным точечным источником энергии избыточная предельная температура в точке, перемещающейся вслед за источником со скоростью источника и на расстояния R_x1 от него, определяется зависимостью
T₂(R) =

·exp

-

(R

-x′)

, (6) где V - скорость движения источника и термоприемника, а - коэффициент температуропроводности исследуемого материала; Х^I - расстояние между центром пятна нагрева и проекцией точки R_x на линию движения источника тепла (см. фиг. 1).The loss of thermal energy into the environment when passing the temperature control point, the distance from the heating spot to the point with coordinate R ₁ at power q ₁ will be determined by the expression
Δq ₁ = α

[T ₁ (R) -T _s ] dR = S ₁ (R) (4) So that the energy loss to the environment when the source power q ₁ would be equal to the loss Δq ₁ . experimentally find such a distance R _x1 between the control point of the excess temperature and the heating spot at which
Δq ₂ = α

[T ₂ (R) -T _s ] dR = S ₂ (R

) = S ₁ (R) (5) When the surface of the body under study is heated by a moving point source of energy, the excess limit temperature at the point moving after the source at the speed of the source and at a distance R _x1 from it is determined by the dependence
T ₂ (R) =

Exp

-

(R

-x ′)

, (6) where V is the speed of movement of the source and thermal receiver, and is the coefficient of thermal diffusivity of the studied material; X ^I - the distance between the center of the heating spot and the projection of the point R _x on the line of motion of the heat source (see Fig. 1).

(7) Чтобы тепловые потери в окружающую среду от конвективного и лучистого теплообмена при измененной мощности источника q₂ были бы равны потерям Δq₁ ^пот, экспериментально определяют такое расстояние R_x2по линии движения источника между точкой контроля температуры и пятном нагрева, при котором
Δq $\genfrac{}{}{0ex}{}{\text{п}}{\text{3}}$ ^от= α

[T₃(R)-T_с] dR= S₃(R

)= S₁(R₁) (8) При этом значение контролируемой температуры будет определяться выражением
T₃(R) =

(9) Так как из условия эксперимента Δ q₁ ^пот= Δ q₃ ^пот, то после несложных математических преобразований выражений (2) и (9), получим формулу для расчета теплопроводности в следующем виде:
λ =

. (10) Таким образом, определив расстояния R_x1 и R_x2, при которых тепловые потери в окружающую среду с поверхности исследуемого тела будут равны потерям при движении термоприемника на заданное расстояние R₁ от источника тепла, а также измерив соответствующие этим трем расстояниям значения предельных избыточных температур, зная мощность источника и скорость его движения над поверхностью тела, по формулам (7) и (10) можно определить искомые теплофизические характеристики.Since it follows from (4) and (5) that Δ q ₁ ^sweat = Δ q ₂ ^sweat , then after simple mathematical transformations of expressions (2) and (6), we obtain a formula for calculating thermal diffusivity in the form:
a =

(7) In order for the heat loss to the environment from convective and radiant heat transfer with a changed source power q ₂ to be equal to losses Δq ₁ ^sweat , experimentally determine such a distance R _x2 from the source’s line of movement between the temperature control point and the heating spot at which
Δq $\genfrac{}{}{0ex}{}{\text{P}}{}$$\genfrac{}{}{0ex}{}{}{\text{3}}$ ^from = α

[T ₃ (R) -T _s ] dR = S ₃ (R

) = S ₁ (R ₁ ) (8) In this case, the value of the controlled temperature will be determined by the expression
T ₃ (R) =

(9) Since from the experimental condition Δ q ₁ ^sweat = Δ q ₃ ^sweat , after simple mathematical transformations of expressions (2) and (9), we obtain a formula for calculating thermal conductivity in the following form:
λ =

. (10) Thus, having determined the distances R _x1 and R _x2 at which the heat loss to the environment from the surface of the test body will be equal to the loss when the heat detector moves a predetermined distance R ₁ from the heat source, and also by measuring the corresponding excess temperatures, knowing the power of the source and the speed of its movement above the surface of the body, using the formulas (7) and (10), one can determine the desired thermophysical characteristics.

 In FIG. 2 shows a diagram of a device that implements the proposed method.

 The device consists of a source of thermal energy 1 focused on the surface of the test product 2, a heat detector 3 located above the surface of the test product, focused on it. The thermal receiver is connected to the information inputs of the first and second electronic keys 4 and 5, the output of the first key is connected to the input of the voltage converter 6 to the frequency, the output of which is in turn connected to the informative input of the reverse counter 7. The output of the second electronic key through the first analog-to-digital converter 8 connected to the first input of the Central processor 9, the second input of which is connected via the input-output device 10 to the keypad 11. One of the outputs of the keypad 11 is connected to the control input of the third electronic key 12, the information input of which is connected to the rechord of the first potentiometer 13, and the output is connected to the first input of the comparator 14, the second input is connected to the output of the reference voltage setting unit (settings) 15. The input of block 15 is connected to the remote control 11. The output of the comparator 14 is connected to the control input of the first electronic key 4 and the input of the inverter 16, the output of which is connected to the control input of the second electronic key 5. The rechord of the first potentiometer 13 is connected to the first information input of the fourth electronic key 17, the control input of which is connected to the output of the reverse counter 7 and the output through the second analog-to-digital converter 18 is connected to the third input of the central processor 9. The reochord of the potentiometer 13 is also connected to the control circuit of the magnetic starter I am 19 of the reversible motor 20, the power circuit of which is connected through the polarity switch 21 to the power supply unit of the motor 22, and the motor shaft is connected to the mechanism 23 for moving the thermal receiver 3 relative to the source 1 along the X-axis, and also to the mechanism 24 for moving the thermal receiver along the Y- axis Cove. Potentiometers 13 and 25 are connected to a stabilized voltage source 26. The movement mechanism of the thermal receiver 23 is connected to the reochord of the first potentiometer 13, and the movement mechanism 24 is connected to the reochord of the second potentiometer 25. The reochord of the second potentiometer 25 is connected to the second information input of the electronic key 17. The output of the power supply unit 27 is connected to the input of the energy source 1, and the circuit control unit of the power supply 27 is connected to the control unit 11, which in turn is connected to the polarity switching unit 21 and the control circuits of the magnetic starter 19 and the mechanism 28 for moving the energy source 1 and thermal receiver 3 relative to sample 2. The information output of the central processor 9 through the output device 29 is connected to the indicator 30 and the information inputs of the counter 5. The output of the reverse counter 7 is connected to the control inputs of the second and fourth electronic keys 5 and 17, as well as to the magnetic control circuit starter 19. The output of the comparator 14 is also connected to the control circuits of the magnetic starter 19 and the movement mechanism 28.

The device implements the proposed method as follows. The operator before starting the measurement from the keypad 11 controls the program for calculating the thermophysical characteristics, constructed in accordance with dependences (7) and (10). Then, on command from the control panel, the device is restored to its initial state: the first 4, second 5, third 12 and fourth 17 electronic keys are closed, the counter 7 is reset, the setpoint block 15 is set to a voltage proportional to the value of the set distance R ₁ , the magnetic starter is turned on 19, while the reversible motor 20 through the movement mechanism 23 moves the thermal receiver 3 relative to the source 1 until the temperature control point coincides with the heat exposure point, while the rechord of the potentiometer 13 is established a zero position and the zero signal from it switches off the magnetic contactor 19, t. e. lock motor 20 realized.

=

определяется расстояние R_x1 между источником 1 и термоприемником. При этом открывается ключ 5 и информация о температуре Т₂(R_x1 ) в точке R_x1 с термоприемника 3 через ключ 5 и АЦП 8 запишется в оперативную память процессора. Далее по команде с пульта 11 управления термоприемник 3 перемещается в исходное нулевое положение, подается сигнал на блок 27 питания, по которому мощность теплового воздействия становится равной q₂. Из оперативной памяти процессора 9 информация об интегральном значении температуры S₁(R₁) через блок 29 вывода по информативному входу заносится в счетчик 5. После этого по команде с пульта управления переключается блок 21, включается механизм 28 перемещения термоприемника и источника и механизм 23 перемещения, включается пускатель 19 и двигатель 20, открывается электронный ключ 4, а реверсивный счетчик 7 переключается в режим вычитания. Перемещение термоприемника относительно источника происходит до тех пор, пока не обнулится реверсивный счетчик 7, что произойдет при выполнении условия (5) S₁(R₁) = S₃(R_x2), т. е. условия равенства контролируемых интегральных по расстоянию значений температур. При этом сигналом с выхода счетчика 7 выключается магнитный пускатель 19 и происходит остановка двигателя 20, открывается ключ 17 и информация о расстоянии R_x2 через второй аналого-цифровой преобразователь 18 заносится в оперативную память микропроцессора, открывается электронный ключ 5 и информация Т₃(R_x2) об избыточной контролируемой температуре в точке R_x2 с термоприемника 3 через ключ 5 и аналого-цифровой преобразователь 8 запишется в оперативную память микропроцессора 9.The device is started by the operator by issuing a command from the control panel 11 to turn on the power supply unit 1 of the energy source 1, turn on the mechanism for moving the source 1 and the thermal receiver 3 relative to the test product 2, switch the power polarity by unit 21, turn on the starter 19 and start the engine 20, which is through the mechanism 23 carries out the movement of the thermal receiver 3 in the direction of lagging from the source 1, the opening of electronic keys 4, 5 and 12. When moving the thermal receiver from the point of thermal influence on the test product Other information about the integral value of the controlled excess temperature S ₁ (R) is entered in counter 7. Since the stabilized supply voltage in block 24 is selected so that when moving the rechord of potentiometer 13 by a unit of length, the voltage value taken from the rechord is strictly proportional to the selected unit linear movement, then when the thermal receiver passes a predetermined distance R ₁ from source 1, the reochord kinematically connected with the thermal receiver will also move to the distance R ₁ . In this case, the signal from the re-chord supplied through the key 12 to the input of the comparator 14 will become equal to the value of the setpoint applied to the second input of the comparator 14. The latter will then switch to the state of the logical unit by closing the electronic key 4 by direct output, turning off the starter 19 of the engine 20, the mechanism 28 displacement and opening through an inverter 16 key 5. Information of excess temperatures T ₁ (R ₁₎ at the control point at a distance R ₁ from termopriemnika 3 through the switch 5 and the first analog-to-digital converter 8 is written into memory of the microprocessor 9. Then, on command from the control panel 11, the mechanism 28 for moving the source and the thermal receiver is turned off, the polarity of the power of the reversing motor 20 is switched, the magnetic starter 19 is turned on and the thermal receiver 3 is moved to the energy source 1 with the mechanism 23 until the temperature control point coincides with the heat exposure point, when this blocking turns off the starter motor 20. After this, at the command of the control panel, the unit 21 is switched on, the engine 20 is turned on, and through the mechanism 23 for moving the thermal receiver 3 is placed until it coincides with the point of thermal influence, while the rechord of potentiometer 13 is set to zero and the engine 20 is turned on. Then, by command from the remote control 11, the power supply polarity of the engine 20 is switched and the movement mechanisms along the X-axis 23 and the Y- axis are turned on kov 24. The electronic key 4 is opened, and the reverse counter 7 switches from the summation mode to the subtraction mode. The movement of the thermal receiver relative to the source occurs until the reversible counter 7 is reset to zero, which will happen when condition (5) S ₁ (R ₁ ) = S ₂ (R _x1 ) is fulfilled. In this case, the signal from the counter 7 turns off the magnetic starter and the engine 20 stops, the key 17 opens and information from the rechords 13 and 25 about the distance x ^I , through the second ADC is entered into the RAM of the processor 9, where, in accordance with the R algorithm

=

the distance R _x1 between the source 1 and the thermal receiver is determined. This opens the key 5 and the temperature information T ₂ (R _x1 ) at the point R _x1 from the thermal receiver 3 through the key 5 and the ADC 8 is recorded in the RAM of the processor. Further, on command from the control panel 11, the thermal detector 3 moves to its initial zero position, a signal is supplied to the power supply unit 27, by which the thermal power becomes equal to q ₂ . From the RAM of the processor 9, information about the integral temperature S ₁ (R ₁ ) through the output unit 29 is inputted to the counter 5 via the informative input. After this, the unit 21 is switched by a command from the control panel, the thermal receiver and source movement mechanism 28 and the movement mechanism 23 are turned on , the starter 19 and the engine 20 are turned on, the electronic key 4 is opened, and the reverse counter 7 switches to the subtraction mode. The thermal receiver moves relative to the source until the reverse counter 7 is reset to zero, which will happen when condition (5) S ₁ (R ₁ ) = S ₃ (R _x2 ) is fulfilled, i.e., the conditions for the equality of the controlled temperature-integral values of distance . In this case, the signal from the output of the counter 7 turns off the magnetic starter 19 and the motor 20 stops, the key 17 and distance information R _{x2 are} opened through the second analog-to-digital converter 18, it is entered into the microprocessor RAM, the electronic key 5 and information T ₃ (R _x2 ) about the excess controlled temperature at point R _x2 from the thermal receiver 3 through the key 5 and the analog-to-digital converter 8 is recorded in the RAM of the microprocessor 9.

Using the found value of R _x1 , R _x2 , T ₁ (R ₁ ) and T ₂ (R _x1 ), T ₃ (R _x2 ), as well as information on the power of thermal effects q ₁ and q ₂ and speed V according to the program built in in accordance with formulas (7) and (10), introduced into the microprocessor 9, the values of the sought quantities are calculated. The found values of thermophysical characteristics are stored in the RAM of the microprocessor and can be called by the operator to the indicator device 30 at any time after the end of the experiment.

 The proposed method allows to take into account in the measurement results the desired thermophysical characteristics of heat loss to the environment, which significantly improves the metrological quality of the developed method. A big advantage of the proposed method is that it allows in the absence of information about the ambient temperature, the heat transfer coefficient α, which cannot be determined with great accuracy, and in practice its value is taken, as a rule, approximately, in the absence of information about the surface condition of the controlled products, determine losses to the environment and amend the measurement results accordingly, which ultimately increases the reliability and accuracy of the information about the desired heat and temperature coefficients oprovodnosti.

 The proposed device allows you to automatically determine and introduce corrections for heat loss from the product into the environment, register and process measurement information in digital form, increases noise immunity and reliability of the results.

 The conducted experimental verification showed that the proposed technical solution compared to the known methods and devices made it possible to increase the accuracy of measurement results by taking into account heat losses from the heated test surface into the environment by 3-5%. The results of a series of experiments on products with known thermophysical characteristics, carried out using the claimed solution and prototypes, are shown in the table.

Claims (2)

1. The method of non-contact measurement of the thermophysical characteristics of materials, which consists in the fact that they act on the surface of the body with a point moving source of heat of a certain power, measure the excess temperature of the heated surface of the line of its movement and on a parallel line, measure the distance between the temperature control point and the center of the heating spot the source and the magnitude of excess temperatures determine the desired values, characterized in that they place the temperature control point in the center of the spot on heating, shift the temperature control point from the heating spot along the line of movement of the source to the backward lag by a predetermined distance, while measuring the distance-integral value of the excess limit temperature in the segment of movement from the heating spot to the specified position of the control point, determine the excess temperature in the given position of the control point , place the control point in the center of the heating spot, and then remove it along an arbitrarily chosen straight line in the direction of the lag from the source by a distance at which the integral the distance value of the excess temperature will be equal to the value of the integral temperature obtained when the control point moves along the source line for a given distance, the control point is moved to the center of the heating spot and the power source is measured by a certain amount, the control point is moved from the center of the heating spot along the movement line the source in the direction of lagging behind it by a distance at which the distance-integral value of the excess temperature will be equal to the value of the integral temperature at izhenii of source lines with the initial capacity, and the desired thermal characteristics determined from the relations
a =

; ;
λ =

,,
where λ, a are the coefficients of heat and thermal diffusivity, W / m to; m ² / s;
R ₁ , R _x1 , R _x2 , respectively, the given and found distances between the center of the heating spot and the temperature control point, m;
T ₁ (R ₁ ), T ₂ (R _x2 ), T ₃ (R _x2 ) - excess temperatures at points, respectively, at distances R ₁ , R _x1 and R _x2 from the center of the heating spot at the source power q ₁ and q ₂ , ^o WITH;
V is the speed of movement of the source and the thermal receiver relative to the investigated body, m / s;
X ¹ - the distance between the center of the heating spot and the projection of the point located at a distance R _x1 , on the line of motion of the energy source, m  2. A non-contact device for measuring the thermophysical characteristics of materials, containing a concentrated source of thermal energy and a thermal detector fixed above the surface of the test body, focused on the surface of the body, a mechanism for moving the energy source and thermal detector relative to the test sample, an energy source power supply unit, characterized in that it further comprises four electronic keys, voltage-to-frequency converter, reversible counter, two analog-to-digital converters, trawl processor, input-output unit, keypad, inverter, comparator, magnetic starter and motor power supply unit, polarity switch of the motor power supply circuit, two potentiometers with a stabilized power supply, reference voltage setting unit, two mechanisms for moving the thermal receiver relative to thermal energy, unit output indicator, and the output of the thermal receiver is connected to the information inputs of the first and second electronic keys, and the output of the first key is connected to the input of the Converter I am in the frequency, the output of which, in turn, is connected to the information input of the reverse counter, the output of the second electronic key through the first analog-to-digital converter is connected to the first input of the central processor, the second input of which is connected to the keypad via the input-output device, one of the outputs of the control panel is connected to the control input of the third electronic key, the information input of which is connected to the rechord of the first potentiometer, and the output is connected to the first input of the comparator, W The input of which is connected to the output of the reference voltage setting unit, and the input of the reference voltage setting unit is connected to the control panel, in addition, the comparator output is connected to the control input of the first electronic key and the inverter input, the output of which is connected to the control input of the second electronic key, control input which is connected to the output of the reversible counter, and the output of the fourth key through the second analog-to-digital converter is connected to the third input of the central processor, the rechord of the first potential meter is also connected to the control circuit of the magnetic starter of the reversible motor, the power circuit of which is connected through the polarity switch to the motor power supply, and the starter output is connected to the motor, the shaft of which is connected to the mechanism for moving the thermal receiver relative to the point source of energy in the direction of movement of the source, as well as to the mechanism movement of the thermal receiver in a direction perpendicular to the direction of movement of the source, in addition, the potentiometers are connected to the stabilized source voltage, moreover, the reochord of the first potentiometer is kinematically connected to the mechanism of moving the thermal receiver in the direction of movement of the heat source, the reochord of the second potentiometer is connected to the mechanism of moving the thermal receiver in the direction perpendicular to the direction of movement of the source, the rechords of two potentiometers are connected respectively to the first and second information inputs of the fourth electronic key , the output of the reverse counter is connected to the control input of the fourth electronic key, as well as to the circuit control of the magnetic starter, in addition, the output of the comparator is connected to the magnetic starter and the mechanism for moving the energy source and thermal receiver relative to the test product, and the control panel is connected to the control input of the first and second keys, the power polarity reversing motor reversing motor, the magnetic starter, the source movement mechanism and thermal receiver, reversible counter and power supply unit of the energy source, the information output of the central processor through the output unit is connected to indicator and information inputs of the reverse counter.

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