CN104949758A - Production line infrared thermometer calibrating method - Google Patents

Abstract

The invention provides a production line infrared thermometer emittance calibrating method, which comprises the following steps: 1) between a tapping time of a tested object and measurement times recorded by the production line infrared thermometer, a measurement time with a stable temperature value and recorded by using a handheld thermometer is acquired, and a time difference is calculated; 2) a curve of temperature of the tested object changing along with time is known, theoretical temperatures of two measurement times are obtained, and a theoretical temperature difference of the two measurement times is calculated; 3) a corresponding emittance of the handheld thermometer at the testing time is acquired; 4) according to an emittance-temperature increment formula, a theoretical emittance difference of the two temperature measurement times is acquired; and 5) the emittance difference is subtracted from the emittance of the handheld thermometer to acquire the emittance of the production line infrared thermometer. In the condition of not influencing production, calibration on the thermometer emittance can be directly carried out, and problems of inconvenience, over high cost, difficult realization and the like and economic losses brought by the traditional calibration method can be avoided.

Description

The scaling method of production line infrared thermometer

Technical field

The present invention relates to the scaling method of infrared thermometer emissivity, particularly relate to a kind of scaling method being applicable to the infrared thermometer emissivity of production scene.

Background technology

Infrared thermometer utilizes object radiation to pass thermal property, adopts non-contacting temp measuring method, carries out temperature detection by the radiation energy of object unit area and the relation of temperature to object.The emissivity of infrared thermometer is the major parameter affecting measurement result, emissivity inaccurate, directly can affect the accuracy of production scene infrared thermometer thermometric, thus directly affect production run and result.The inaccurate reason of current emissivity: 1) emissivity of testee changes with testee kind; 2) emissivity of testee varies with temperature; 3) emissivity of testee changes with surface quality; 4) testee emissivity changes with thermometric condition (thermometric environmental factor, thermometric angle, visual field fullness rate etc.).

Adopt the method for laboratory test, because its operating mode and actual production operating mode are variant, it is not accurate enough that the emissivity of acquisition is directly used in production; And adopt production line direct calibration method (utilizing the methods such as synchronous thermocouple temperature measurement calibration principle) although be correct in principle, but transient state thermal source is belonged to for testee, and the field condition that its locus changes again in time, this kind of method has many difficulties in actual applications (as the layout of thermopair, the sample and transform of data, that demarcates is synchronous, switching on and shutting down debugging etc.).

Therefore need a kind of scaling method, can avoid laboratory testing method bring inaccurate, the performance difficulty that production line direct calibration method is brought can be avoided again.

Summary of the invention

Technical matters to be solved by this invention is exactly for current infrared emittance scaling method above shortcomings, provides a kind of scaling method of production line infrared thermometer emissivity, for solving the problems of the prior art.

For achieving the above object and other relevant objects, the invention provides a kind of emissivity scaling method of production line infrared thermometer, comprise the following steps:

1) at testee from the moment t that comes out of the stove ₀start, until the measurement moment t of production line infrared thermometer record ₂between, obtain the measurement moment t utilizing hand-held temperature measurer record that has equilibrium temperature value ₁, calculate t ₁and t ₂mistiming Δ t;

2) known testee temperature change curve in time, obtains two measurement moment t in step 1) ₁and t ₂theoretical temperatures T ₁and T ₂, calculate two and measure moment t ₁and t ₂theoretical temperatures difference Δ T=T ₂-T ₁;

3) hand-held temperature measurer is obtained at test moment t ₁time corresponding emissivity ε ₁;

4) according to emissivity-temperature increment formula, obtain the theoretical emission rate difference DELTA ε in two thermometric moment, described emissivity-temperature increment formula is as follows:

Δε＝4.4621×10 ^-4ΔT

5) emissivity ε of the hand-held temperature measurer obtained in step 3) is utilized ₁deduct the emissivity difference DELTA ε obtained in step 4), obtain the emissivity ε of production line infrared thermometer ₂.

Further, in described step 3), under presetting same thermometric condition, the testee emissivity of multiple time period and the increment relation of measuring tempeature.

Further, in described step 3), according to hand-held temperature measurer at test moment t ₁corresponding temperature T ₁carry out the adjustment of hand-held temperature measurer emissivity, be adjusted in emissivity , obtain t respectively ₁corresponding temperature , obtain ε according to mathematic interpolation ₁.

By above technical scheme, production line infrared thermometer emissivity scaling method of the present invention, adopts the mode of environmental error cancellation, achieves and directly demarcate infrared thermometer emissivity in production scene.When not affecting production, the demarcation of temperature measurer emissivity be can directly carrying out, inconvenience that traditional direct calibration method brings, high cost, the economic loss that is difficult to the problems such as realization and brings avoided.

Accompanying drawing explanation

Fig. 1 is the scaling method schematic flow sheet of production line infrared thermometer of the present invention;

Fig. 2 is testee temperature change curve in time;

Fig. 3 is the increment relation figure of testee emissivity and temperature.

Embodiment

By particular specific embodiment, embodiments of the present invention are described below, person skilled in the art scholar the content disclosed by this instructions can understand other advantages of the present invention and effect easily.

Refer to Fig. 1 to Fig. 3.Notice, structure, ratio, size etc. that this instructions institute accompanying drawings illustrates, content all only in order to coordinate instructions to disclose, understand for person skilled in the art scholar and read, and be not used to limit the enforceable qualifications of the present invention, therefore the not technical essential meaning of tool, the adjustment of the modification of any structure, the change of proportionate relationship or size, do not affecting under effect that the present invention can produce and the object that can reach, still all should drop on disclosed technology contents and obtain in the scope that can contain.Simultaneously, quote in this instructions as " on ", D score, "left", "right", " centre " and " one " etc. term, also only for ease of understanding of describing, and be not used to limit the enforceable scope of the present invention, the change of its relativeness or adjustment, under changing technology contents without essence, when being also considered as the enforceable category of the present invention.

One, this scaling method principle explanation

The object emission rate recorded under different thermometric conditions differs greatly, and its emissivity recorded is:

$\mathrm{\ϵ}=\stackrel{\‾}{\mathrm{\ϵ}}+\mathrm{\Δ}{\mathrm{\ϵ}}^{\′}---\left(1\right)$

Wherein: the emissivity of ε-record; the emissivity true value of-testee; The emissivity deviation of Δ ε '-caused by thermometric condition difference.

And the emissivity deviation delta ε ' under different thermometric conditions is different, so directly adopt emissivity measured under different thermometric conditions to be directly used for demarcating production line emissivity, larger error can be produced.Therefore adopt the emissivity value that laboratory obtains, demarcating the temperature measurer emissivity of production scene, is not rigorous.

Due under identical thermometric condition, the emissivity deviation delta ε ' caused by thermometric environment and condition is close.Therefore, error elimination method can be utilized, demarcate, the error that this part causes can be fallen by basic neutralisation.Such as at present respectively at two environment (a ₁, a ₂) under record two temperature (T respectively ₁, T ₂) emissivity.Can at environment a ₁the increment relation of lower acquisition emissivity and temperature, utilizes its increment relation to counteract the characteristic of the error caused by thermometric condition, and then can in the hope of at environment a ₂the emissivity of lower target temperature.

That is:

${\mathrm{\ϵ}}_{a_1,T_1}={\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1,T_1}+\mathrm{\Δ}{{\mathrm{\ϵ}}^{\′}}_{a_1,T_1}---\left(2\right)$

${\mathrm{\ϵ}}_{a_1,T_2}={\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1,T_2}+\mathrm{\Δ}{{\mathrm{\ϵ}}^{\′}}_{a_1,T_2}---\left(3\right)$

${\mathrm{\ϵ}}_{a_2,T_1}={\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2,T_1}+\mathrm{\Δ}{{\mathrm{\ϵ}}^{\′}}_{a_2,T_1}---\left(4\right)$

${\mathrm{\ϵ}}_{a_2,T_2}={\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2,T_2}+\mathrm{\Δ}{{\mathrm{\ϵ}}^{\′}}_{a_2,T_2}---\left(5\right)$

Wherein a ₁, a ₂-two thermometric environment, T ₁, T ₂-intend thermometric temperature place temperature range endpoint value.

Due under identical thermometric condition, the emissivity deviation delta ε ' caused by thermometric environment and condition is close, that is:

${{\mathrm{\Δ\ϵ}}^{\′}}_{a_1,T_2}\≈{{\mathrm{\Δ\ϵ}}^{\′}}_{a,T_1},$

Therefore:

$\mathrm{\Δ}{\mathrm{\ϵ}}_{a_1}{|}_{T_2,T_1}=({\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1,T_2}-{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1,T_1})+({{\mathrm{\Δ\ϵ}}^{\′}}_{a_1,T_2}-{{\mathrm{\Δ\ϵ}}^{\′}}_{a_1,T_1})\≈{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1,T_2}-{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1,T_1}=\mathrm{\Δ}{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1}{|}_{T_2,T_1}---\left(6\right)$

In like manner, at thermometric environment a ₂under, have:

$\mathrm{\Δ}{\mathrm{\ϵ}}_{a_2}{|}_{T_2,T_1}=({\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2,T_2}-{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2,T_1})+({{\mathrm{\Δ\ϵ}}^{\′}}_{a_2,T_2}-{{\mathrm{\Δ\ϵ}}^{\′}}_{a_2,T_1})\≈{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2,T_2}-{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2,T_1}=\mathrm{\Δ}{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2}{|}_{T_2,T_1}---\left(7\right)$

Under different thermometric conditions, testee is under same temperature ranges stated, and the difference of its emissivity true value is identical, that is:

$\mathrm{\Δ}{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2}{|}_{T_2,T_1}=\mathrm{\Δ}{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1}{|}_{T_2,T_1}$

Therefore:

${\mathrm{\Δ\ϵ}}_{a_1}\≈\mathrm{\Δ}{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_2}{|}_{T_2,T_1}=\mathrm{\Δ}{\stackrel{\‾}{\mathrm{\ϵ}}}_{a_1}{|}_{T_2,T_1}\≈\mathrm{\Δ}{\mathrm{\ϵ}}_{a_2}---\left(8\right)$

Two, testee temperature and the explanation of emissivity increment relation preparation method

The increment relation of testee temperature and emissivity can obtain from document, also obtains by test.The experimental technique adopted for this example obtains the increment relation of testee and emissivity, as shown in Figure 3, the method for testee temperature and emissivity increment relation is described.

Experimentation is as follows.

1) under each plate holding temperature of specifying, the emissivity of setting infrared thermometer, after the temperature retention time of regulation, measures the plate temperature in stove, record infrared thermometer displays temperature.

2) then set new emissivity and repeat above-mentioned steps, until the relation of the temperature value that infrared emittance and infrared thermometer show under obtaining this holding temperature.

3) recycle differential technique and obtain emissivity at this plate temperature of specifying.

4) 1 is utilized)-3) step records each temperature emissivity of specifying.

5) above-mentioned 1 is utilized)-4) finally to obtain the increment formula of plate emissivity and temperature as follows for this experiment emissivity rule matching that obtains of each step:

Δε＝4.4621×10 ^-4ΔT

Wherein: Δ ε-emissivity increment; Δ T-testee temperature difference, DEG C.

Three, the production scene thermometric condition of this routine Analysis and interpellation

1. thermometric condition stub

Plate is warmed up to about 930 DEG C in a furnace, and plate temperature is in uniform state substantially, is coming out of the stove in a flash, and namely come out of the stove moment t ₀, plate bulk temperature is substantially all at 930 DEG C, and substantially even.Plate, after coming out of the stove, is transported to " treating progressive die district " by travelling belt, and in transport process, due to plate, spatially the moment moves, and speed, inconvenience is selected to measure moment t as hand-held temperature measurer ₁, and plate arrives " treating progressive die district " moment, has the space of about 2 ~ 3 seconds to pause the period, this time provides possibility just to hand-held temperature measurer measurement, and the moment of so hand-held thermometric is t ₁, the on-the-spot emissivity recorded is ε ₁.T ₁in the moment, plate does not contact with other instruments, and plate belongs to uniform decrease in temperature, each several part temperature close.So, a part can be selected to be full of hand-held temperature measurer visual field in plate body region, using this body region temperature as plate temperature, can emissivity ε be measured ₁.

2. hand-held temperature measurer temperature and the explanation of emissivity relation principle

Gray-body radiation degree and temperature relation:

$j_g^{*}=\mathrm{\ϵ}\·j^{*}={\mathrm{\ϵ\σT}}^4$

Wherein: -grey body total radiation degree, W/m ²; ε-grey volume emissivity; σ-Si Difen-Boltzmann constant σ=5.670400 × 10 ^-8w/ (m ²k ⁴); j ^*-black matrix total radiation degree, W/m ².

When testee one timing, it is certain (in thermometric moment, in unit area, liberated heat is certain).The i.e. unit interval, the radiation energy that unit area instrument receives is certain.And σ is a constant.Therefore the test moment can be regarded as, ε and T ⁴be inversely proportional to.Therefore ε can be adjusted to obtain temperature T.When hand-held infrared thermometer, when being adjusted to ε ', the temperature T' of acquisition is just equal with theoretical temperatures or close, and so ε ' is the on-the-spot emissivity in this moment.Or differential technique also can be adopted to calculate, according to the adjustment that the temperature T1 that the t1 moment is corresponding carries out hand-held temperature measurer emissivity, be adjusted in emissivity under, obtain t respectively ₁corresponding temperature , can ε be obtained according to mathematic interpolation ₁.

3. record ε ₁necessity explanation

Be applied to the timing signal in production scene, needing on the production line demarcated, after testee enters mould, production line infrared video camera starts shooting, and this moment is t ₂, corresponding emissivity is ε ₂.Now testee contacts with part mould or chuck, forms Non-isothermal Temperature Field.So be a temperature field by the image of the temperature measurer acquisition of demarcating, there is certain temperature range in this temperature field.If directly with the theoretical temperatures T in this temperature measurer shooting moment ₂directly go to adjust emissivity ε ₂, can be obtained several and contain T ₂temperature range, thus cannot obtain the ε determined ₂value, such as: at T ₂the situation of=500 DEG C, the ε of adjustment ₂when=0.5, obtaining temperature range is [350,55] 0 DEG C, and adjusts ε ₂when=0.4, the temperature range of acquisition is [450,65] 0 DEG C, and these two temperature ranges all comprise T ₂=500 DEG C, but the emissivity ε of correspondence ₂different.In this case, be difficult to directly carry out the accurate ε 2 of demarcation acquisition one to it by this temperature range.

So, if at tested plate from the moment t that comes out of the stove ₀start, until the measurement moment t of production line infrared thermometer record ₂between, a measurement moment t utilizing hand-held temperature measurer record with equilibrium temperature value can be found ₁, draw ε ₁.Pass through emissivity ε ₁deduct emissivity difference DELTA ε, the actual transmission rate ε of production line infrared thermometer can be obtained ₂.

4. temp measuring method embodiment

According to above-mentioned principle, the concrete calibration process be applied in production scene is as follows, as shown in Figure 1:

1) at testee from the moment t that comes out of the stove ₀start, until the measurement moment t of production line infrared thermometer record ₂between, obtain the measurement moment t utilizing hand-held temperature measurer record that has equilibrium temperature value ₁, calculate t ₁and t ₂mistiming Δ t;

2) known testee temperature change curve in time, obtains two measurement moment t in step 1) ₁and t ₂theoretical temperatures T ₁and T ₂, calculate two and measure moment t ₁and t ₂theoretical temperatures difference Δ T=T ₂-T ₁;

3) hand-held temperature measurer is obtained at test moment t ₁time corresponding emissivity ε ₁;

4) according to emissivity-temperature increment formula, obtain the theoretical emission rate difference DELTA ε in two thermometric moment, described emissivity-temperature increment formula is according to test findings fitting formula, as follows:

Δε＝4.4621×10 ^-4ΔT

5) emissivity ε of the hand-held temperature measurer obtained in step 3) is utilized ₁deduct the emissivity difference DELTA ε obtained in step 4), obtain the emissivity ε of production line infrared thermometer ₂.

5. embody rule illustrates

Below to demarcate the infrared thermometer emissivity of certain production scene, carry out the citing of embodiment, testee is the metal blank that high temperature is come out of the stove.

1) adopt hand-held infrared thermometer to resting on the test (treat progressive die district plate come out of the stove moment be about t1=3.5s) treating the emissivity that the plate in progressive die district has carried out after coming out of the stove, by the plate temperature change curve (Fig. 2 shown in) in time of verification or experimental record, find corresponding temperature, T ₁≈ 850 DEG C.Adopt this thermometric condition to carry out the mensuration of hand-held infrared thermometer emissivity, measuring emissivity is ε 1=0.63.

2) calculating production line infrared thermometer time that moment distance testee comes out of the stove of taking pictures is about t2=9.9s, by plate temperature in time change curve learn the temperature T that this time is corresponding ₂≈ about 750 DEG C.

Twice probe temperature difference DELTA T=750-850=-100 DEG C, according to increment formula Δ ε=4.4621 × 10 ^-4Δ T draws, corresponding emissivity difference is about-0.04621.

3) calculate plate and be about 0.63-0.04621=0.58379 in the emissivity that production line infrared thermometer photo opporunity point is corresponding.

Calibration result is verified:

1) emissivity checking is carried out to production scene infrared thermometer, carried out the emissivity setting that emissivity is 0.5,0.6,0.7 3 section respectively, obtained corresponding temperature-measuring results.

2), when emissivity is 0.6, recording plate body temperature is 728.3 DEG C.The emissivity 0.58379 corresponding temperature 750 DEG C of results obtained with theory are close, prove scaling method of the present invention success.

In sum, the scaling method of production line infrared thermometer of the present invention, adopts the mode of environmental error cancellation, achieves and directly demarcate infrared thermometer emissivity in production scene, propose the infrared emittance scaling method being suitable for production scene.This measuring method when not affecting production, can directly carry out the demarcation of temperature measurer emissivity, avoids inconvenience that traditional direct calibration method brings, high cost, the economic loss that is difficult to the problems such as realization and brings.So the present invention effectively overcomes various shortcoming of the prior art and tool high industrial utilization.

Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all without prejudice under spirit of the present invention and category, can modify above-described embodiment or changes.Therefore, such as have in art usually know the knowledgeable do not depart from complete under disclosed spirit and technological thought all equivalence modify or change, must be contained by claim of the present invention.

Claims (3)

1. an emissivity scaling method for production line infrared thermometer, is characterized in that, comprise the following steps:

1) at testee from the moment t that comes out of the stove ₀start, until the measurement moment t of production line infrared thermometer record ₂between, obtain the measurement moment t utilizing hand-held temperature measurer record that has equilibrium temperature value ₁, calculate t ₁and t ₂mistiming Δ t;

2) known testee temperature change curve in time, obtains two measurement moment t in step 1) ₁and t ₂theoretical temperatures T ₁and T ₂, calculate two and measure moment t ₁and t ₂theoretical temperatures difference Δ T=T ₂-T ₁;

3) hand-held temperature measurer is obtained at test moment t ₁time corresponding emissivity ε ₁;

4) according to emissivity-temperature increment formula, obtain the theoretical emission rate difference DELTA ε in two thermometric moment, described emissivity-temperature increment formula is as follows:

Δε＝4.4621×10 ^-4ΔT

5) emissivity ε of the hand-held temperature measurer obtained in step 3) is utilized ₁deduct the emissivity difference DELTA ε obtained in step 4), obtain the emissivity ε of production line infrared thermometer ₂.

2. the emissivity scaling method of production line infrared thermometer according to claim 1, is characterized in that, in described step 3), under presetting same thermometric condition, and the testee emissivity of multiple time period and the increment relation of measuring tempeature.

3. the emissivity scaling method of production line infrared thermometer according to claim 1, is characterized in that, in described step 3), according to hand-held temperature measurer at test moment t ₁corresponding temperature T ₁carry out the adjustment of hand-held temperature measurer emissivity, be adjusted in emissivity under, obtain t respectively ₁corresponding temperature , obtain ε according to mathematic interpolation ₁.