JP2002045961A - Heating evaluating method for heating furnace, and method for estimating temperature of body to be heated using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantify the heating characteristic in a heating evaluating method of a beating furnace. SOLUTION: The temperature change of a test piece is measured by heating the test piece having identified physical properties while moving it in the heating furnace, the temperature change of the test piece in the heating furnace is calculated by using a differential equation with the heating characteristic of the heating furnace as parameter variables, the calculation is repeated by changing the value indicating the heating characteristic of the heating furnace so that the difference between the measured temperature of the test piece and the calculated value becomes minimum, and the optimum heating characteristic is determined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating heating of a heating furnace, and is particularly suitable for use in a reflow soldering method using a reflow apparatus for soldering.

[0002]

2. Description of the Related Art Generally, soldering of electronic components to the surface of a substrate is performed in a batch by inserting the substrate on which the electronic components are mounted into a reflow furnace and moving the inside of the furnace by a conveying means such as a belt conveyor. I have. At this time, conventionally, the optimum heating condition of the reflow furnace has been obtained by measuring the actual temperature of the substrate and changing the condition until a target temperature is obtained. This method of setting heating conditions requires skilled skills, and has to be repeated many times, which is not efficient.

Therefore, there is a technique for efficiently obtaining a temperature change of a substrate based on a certain measurement result. In this technology, the temperature condition of the reflow furnace is divided into a plurality of areas,
First, move the substrate in a reflow furnace under certain heating conditions,
Measure the temperature change of the substrate. Then, based on this temperature change, it becomes possible to calculate and predict the temperature change of the substrate when the furnace temperature setting in each region or the speed of the conveyor which affects the heating time of the substrate is changed. ing.

[0004]

However, in the above-described method for estimating a change in temperature, since only one value is used as the set temperature in each region, when a plurality of types of heating sources are used, the temperature may vary. In some cases, the predicted calculated temperature may differ from the actually measured temperature. in this way,
Using only one value as the set temperature does not take into account the features related to the heating of each heating source when using a plurality of types of heating sources. This corresponds to not taking into account heating characteristics such as infrared emissivity depending on the infrared heater.

In view of the above problems, an object of the present invention is to quantify heating characteristics in a heating furnace heating evaluation method. It is another object of the present invention to accurately predict a temperature change of an object to be heated by a heating furnace.

[0006]

According to the first aspect of the present invention, there is provided a heating furnace provided with a heating means (2) and a conveying means (4). In a heating furnace heating evaluation method for heating a body to be heated by a heating means while moving the body to be heated by a conveying means in a furnace, a test member (10) having a clear thermal property value is prepared.
The test member is heated while being moved in the heating furnace, the time change of the temperature of the test member is measured, and the heating characteristic of the heating furnace is used as a parameter variable, using the thermal properties of the test member,
Numerical analysis is performed on the temperature and time of the test member, and parameter variables are determined so that the deviation between the temperature change of the test member by the numerical analysis and the measured temperature change of the test member is minimized. .

In general, when performing a numerical analysis on a temperature change of a test member, the thermal property value of the test member and the heating characteristics of the heating furnace are required. In the present invention, the thermal property values of the test member are clear, and the temperature change of the test member is also measured in advance, so that an appropriate value is substituted as the heating characteristic of the heating furnace, and a numerical analysis is performed. By appropriately changing the value of the heating characteristic so that the obtained temperature change and the measured temperature change are approximated, the optimal heating characteristic can be obtained. Thus, the heating characteristics of the heating furnace can be quantified.

For example, in the first aspect of the present invention,
As described in the invention, as the heating temperature by the heating means,
Temperature T by infrared heater_hAnd temperature T∞ by hot air convection
Using the density, ρ, specific heat
c, using the infrared absorption coefficient α,
Using flow heat transfer coefficient h, infrared emissivity ε, and view factor F,
The temperature of the test member is T, the surface area is A, the volume is v, and the time is
Is t, the numerical analysis is a differential equation, dT / dt = A /
ρcv · ｛h (T∞−T) + αεF (T_h ^Four-T ^Four)｝
It can be performed using.

According to the third aspect of the present invention, there is provided a heating furnace (1) provided with a heating means (2) and a conveying means (4), wherein the object to be heated is moved in the heating furnace by the conveying means. In the method for estimating the temperature of an object to be heated when the object to be heated is heated by the heating means, a test member (10) having a clear thermal property value is prepared, and the test member is heated while being moved in a heating furnace. Measuring the time change of the temperature of the test member,
Using the heating properties of the heating furnace as a first parameter variable and using the thermal physical property values of the test member, a first numerical analysis is performed on the temperature and time of the test member, and the temperature of the test member is determined by the first numerical analysis. The first parameter variable is determined such that the deviation between the change and the measured temperature change of the test member is minimized. Then, the object to be heated whose thermal physical property value is unknown is heated while moving in the heating furnace, the time change of the temperature of the object to be heated is measured, and the object to be heated is determined using the determined first parameter variable. As a second parameter variable, a second numerical analysis is performed on the temperature and time of the object to be heated, the temperature change of the object to be heated by the second numerical analysis, and the measured In order to minimize the deviation from the temperature change, the second
Are determined, and the temperature change of the object to be heated is obtained by using the determined thermal property values of the object to be heated.

When the thermal properties of each part of the object to be heated are unknown, it is not always possible to accurately determine the temperature change of each part of the object to be heated under arbitrary heating conditions. Therefore, in the present invention, after determining the first parameter variable in the same manner as in the method of determining the parameter variable in claim 1, a second numerical analysis is performed on the temperature change of the object to be heated. At this time, the thermal properties of the object to be heated and the heating characteristics of the heating furnace are required. However, since the heating characteristics have already been obtained by the first numerical analysis, and the temperature change of the object to be heated has been measured in advance. A second numerical analysis is performed by substituting an appropriate value as a thermal physical property value of the object to be heated, and a temperature change of the object to be heated obtained by the second numerical analysis and a temperature change of the object to be heated are measured. As appropriate, by changing the value of the thermal physical property value of the object to be heated as appropriate, the optimal thermal physical property value of the object to be heated can be obtained. If the thermal properties of the object to be heated and the heating characteristics of the heating furnace are known, the temperature change of the object to be heated can be obtained by numerical analysis. Therefore, according to the present invention, it is possible to accurately predict a temperature change of the object to be heated by the heating furnace.

[0011] For example, in the invention of claim 3, as in the invention of claim 4, the heating temperature by the heating means is:
Temperature T∞ due to the temperature T _h and hot air convection by the infrared heater
Using the density ρ ₁ , the specific heat c ₁ , and the infrared absorptivity α ₁ as the thermal physical properties of the test member, and using the convection heat transfer coefficient h, the infrared emissivity ε, and the form factor F as the first parameter variables , The temperature of the test member is T ₁ , the surface area is A ₁ , the volume is v ₁ , the time is t, and the first numerical analysis is a differential equation, dT ₁ / dt = A ₁ / ρ ₁ c ₁ v ₁ · ｛h (T∞−T ₁ )
Performed using the ^{_{+ α 1 εF (T h 4}} -T 1 4)}, T 2 the temperature of the object to be heated, A ₂ surface area, the volume and v _2, and the time t, as a second parameter variables, Using A ₂ / ρ ₂ c ₂ v ₂ and α ₂ , a second numerical analysis is performed using a differential equation, dT ₂ / d
t = A ₂ / ρ ₂ c ₂ v ₂ ｛h (T∞−T ₂ ) + α ₂ εF (T
_h ⁴ -T ₂ ^4)} can be carried out using.

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the concrete means described in the embodiments described later.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, an outline of the present embodiment will be described. In the present embodiment, the following method is performed in order to obtain a heating characteristic specific to a certain heating condition of the heating furnace. First, a test member having a known thermal property value is moved in a heating furnace, and a temperature change of the test member at that time is measured.
Next, a differential equation showing the time change of temperature, dT / dt =
A / ρcv · {h (T∞ -T) + αεF (T h 4 -
T ⁴ ) By using｝, numerical analysis is performed under the same heating conditions of the heating furnace as in the case where the temperature change of the test member is actually measured, and the temperature change of the test member is obtained by calculation.

In this differential equation, the first term on the right side indicates a temperature change caused by hot air convection, and the second term indicates a temperature change caused by heat radiation. T is the temperature of the test member, t is time, A is the surface area of the test member, v is the volume of the test member, T∞
The temperature of the hot air convection, the T _h is the temperature of the heating source the heat radiation. Further, h, ε, and F are values indicating the heating characteristics of the heating furnace, h is a convective heat transfer coefficient depending on hot air convection, ε is an infrared emissivity depending on a heat radiation heat source, and F is a heat radiation A view factor depending on the geometric relationship between the heating source and the test member. Further, ρ, c, and α are thermal physical properties of the test member, ρ is density, c is specific heat, and α is infrared absorptance.

[0015] In the numerical analysis using the above differential equation, since the thermal physical properties of the test member is known, A differential equation, [rho, c, v, alpha, T ∞, substituting constant T _h I do. Since the values of h, ε, and F are unknown, appropriate numerical values are substituted as temporary values. Then, the differential equation is solved to obtain a calculated temperature change.

Next, the calculated temperature change is compared with the actually measured temperature change. Then, so that the deviation between the calculated temperature change and the measured temperature change is small,
The values of h, ε, and F are appropriately changed. Then, the case where the deviation is the smallest is defined as a value (h, ε, F) indicating the heating characteristic of the heating furnace. In this way, the heating characteristics can be determined.

Next, a more detailed description will be given. Hereinafter, a case where a reflow furnace for reflow soldering an electronic component or the like to a printed circuit board is applied as a heating furnace will be described. FIG. 1 is a schematic sectional view of a heating furnace 1 used in the present embodiment. The heating furnace 1 includes a heater 2 including an infrared heater and a fan that transfers heat of the infrared heater into the heating furnace 1 and generates convection of hot air. The heater 2 corresponds to a heating unit.
In the illustrated example, the heating furnace 1 is partitioned by an area 3 having a plurality of heaters 2 arranged at the upper and lower parts of the heating furnace 1. In the heating furnace 1, a chain 4 is disposed as a transfer unit for moving the substrate in the heating furnace 1.

Then, using such a heating furnace 1, a substrate is arranged on the chain 4, the chain 4 is moved by a motor 5 or the like to move the substrate in the heating furnace 1, and the substrate is moved to the heating furnace 1. Heating is performed by the heaters 2 arranged at the upper and lower portions, and the electronic components and the like are soldered to the substrate.

Next, how to determine the heating characteristics of the heating furnace 1 will be described with reference to the flowchart of FIG. First, in step S101, the thermal properties (density ρ,
Using a test member whose specific heat c, infrared absorption rate α), surface area A and volume v are known, the temperature change of the test member when the test member is moved in the heating furnace 1 is measured. FIG. 3 shows a schematic perspective view of a test member used in the present embodiment.

As shown in FIG. 3, a test member 10 includes a holding plate 11 and two kinds of thin film metal plates 12 made of stainless steel or the like.
13 and a temperature sensor 14. The holding plate 11 has two holes formed therein.
Are installed. Of these, the front and back surfaces of one thin film metal plate 12 are highly polished to reduce the infrared absorption, and the front and back surfaces of the other thin metal plate 13 increase the absorption of infrared. For matte black paint. Hereinafter, the thin metal plate which is a highly polished surface is referred to as a mirror plate 12, and the black painted thin metal plate is referred to as a black plate 13. The temperature of each of these thin metal plates 12 and 13 can be measured at any time by a sensor (not shown) or the like. In addition, temperature sensor 1
Reference numeral 4 is arranged at the center of the holding plate 11 to measure the temperature of the atmosphere on the upper and lower surfaces of the holding plate 11.

While the test member 10 is moved by the chain 4, the temperatures of the mirror plate 12 and the black plate 13 are measured by a sensor or the like. Hereinafter, this temperature change is referred to as an actually measured temperature change. FIG. 4 shows the result of the measured temperature change. In the figure, plots indicated by white circles indicate the temperature of the mirror plate 12, and plots indicated by black circles indicate the temperature of the black plate 13.

Next, the temperature change of the mirror plate 12 and the black plate 13 under the same conditions as when the measured temperature change is measured as described above is obtained by numerical analysis using a physical model.
First, the heating furnace 1 is virtually divided into an arbitrary number of heating regions. The number of divisions and the division width of the heating area are determined by the structure of the heating furnace 1, the temperature distribution of the atmosphere, the wind velocity distribution of the hot air, and the like, and are not necessarily the same as the state of the heating furnace 1 partitioned by the heater 2 as described above. They do not have to match. When the heating characteristics are different between the upper surface and the lower surface of the test member 10, the physical properties of the heating characteristics are defined for the upper surface and the lower surface, respectively. In FIG. 4, the time that the test member 10 passes through the boundary of the heating region is indicated by a broken line.

In each heating zone, a convection heat transfer coefficient h, an infrared emissivity ε, and a form factor F are set as values indicating the heating characteristics of the heating furnace 1, and these physical property values are used as parameter variables for the test member. Numerical analysis is performed on the time t change of the temperature T of No. 10.

Then, in step S102,
Appropriate value as the value indicating the heating characteristics in the heating region of
And the heating characteristic in the ith heating zone is h_i,
ε_i, F _iAnd Also, hot air in the i-th heating area
Temperature T∞_i, Infrared heater temperature to T_hiAnd In addition,
In FIG. 4, heat on the upper and lower surfaces of the test member 10 is shown.
Wind temperature T∞_iAre indicated by a dashed line and a bold line, respectively. What
Contact, hot air temperature T∞ on the lower surface_iIs hot air on the top surface
Temperature T∞_iOnly the parts that differ from are shown.

[0025] Then, in step S103, the differential equation, dT / dt = A / ρcv · {h i (T∞ i -T)
By using + αε _i F _i (T _hi ⁴ −T ⁴ )}, the temperature change of the mirror plate 12 and the black plate 13 in each heating region is obtained by numerical calculation. At this time, in each of the mirror plate 12 and the black plate 13, the initial temperature in each heating region is set to be the same as the actually measured temperature, and the temperature change of the mirror plate 12 and the black plate 13 is calculated by numerically calculating each heating region in order. Obtained by

However, the values (h _i , ε _i , F
_Since the value defined in step S102 is used as _i ), this temperature change may not approximate the actually measured temperature change. Therefore, in step S104, it is determined whether the deviation between the calculated temperature change and the actually measured temperature change is minimum. Specifically, the judgment is made based on the result of Σ (measured value−calculated value) ² , and at each time when the temperature change is measured, the difference between the measured value and the calculated value of the temperature is squared, and from the beginning of the temperature change The sum of the squared values is calculated. Then, it is determined whether the sum is minimum.

If it is not the minimum, step S1
02, the value of the heating characteristic is changed and defined again, and a numerical operation is performed in step S103, and a step S1 is performed.
At 04, it is determined whether the deviation between the measured value and the calculated value has been minimized. Then, steps S102 to S104 are repeated until the deviation between the measured value and the calculated value is minimized, and an optimal solution of the heating characteristic is obtained. Thus, the heating characteristics of the heating furnace 1 can be determined.

In FIG. 4, the temperature change using the optimum solution is shown by a solid line for the mirror plate 12, and by a broken line for the black plate 13. As shown in FIG. 4, with respect to the mirror plate 12, the measured temperature indicated by the white circle plot and the temperature calculated by the solid line could be approximated very much. Also, for the black plate 13, the measured temperature shown by the black circle plot and the temperature calculated by the broken line could be made very similar. As described above, the temperature of the one having a low infrared absorptivity (mirror plate 12) and the temperature of the one having a high infrared absorptance (black plate 13) could be approximated.

FIG. 5 shows the result of the same measurement performed by changing the frequency of the fan of the heater 2 which affects the value of the convection heat transfer coefficient h. In this case, the measured temperature change and the calculated temperature are also shown. The change could be very closely approximated.

As described above, since the heating characteristics of the heating furnace 1 are quantified, the measured temperature change and the calculated temperature change can be approximated very much.

It should be noted that the heating by the heater 2 does not need to rely on both hot air convection and radiation from the infrared heater, but may use only one of them. In addition, in order to increase the accuracy of the suitability of the optimal solution, the heating characteristics such as the temperature setting of the heating furnace 1 are appropriately changed, and the heating characteristics are determined so that the measured value and the calculated value under each heating condition are close to each other. Good.

Further, in this embodiment, the frequency of the fan is set to the same value in all the heating regions, but a different frequency may be applied to each heating region as appropriate.

(Second Embodiment) First, an outline of the present embodiment will be described. In the first embodiment, the method for obtaining the heating characteristics of the heating furnace is described. However, in order to predict the temperature change of the object to be heated by the heating furnace, h is calculated in the same manner as in the first embodiment. , Ε, and F, the object to be heated is moved in a heating furnace under the same heating conditions, and the temperature change of the object to be heated at that time is measured. And
The same differential equation as in the first embodiment, dT / dt = A / ρc
v · using {h (T∞-T) + αεF (T h 4 -T 4)}, by performing numerical analysis under the heating conditions of the same heating furnace in the case where a temperature change was measured in the object to be heated, The temperature change of the object to be heated is calculated.

[0034] At this time, this time, h, epsilon, since the F have already _{determined, A, T∞, T h,} h, ε, by substituting a constant to F, with A / ρcv (pseudo concentrated heat capacity) Substitute an appropriate numerical value as a temporary value for α to solve the differential equation. Then, the calculated temperature change is compared with the actually measured temperature change, and the values of A / ρcv and α are appropriately changed so that the deviation between the calculated temperature change and the measured temperature change is reduced. Then, the case where the deviation is the smallest is defined as the thermal physical property value (A / ρcv, α) of the object to be heated.

As described above, since the value of the thermal physical property value can be obtained, if the heating characteristics of the heating furnace are changed, if the heating characteristics are known, the object to be heated can be obtained by using the above differential equation. Temperature change can be obtained. Less than,
More specifically, a case where a reflow furnace for reflow soldering an electronic component or the like to a printed circuit board is applied as a heating furnace will be described.

In general, when an electronic component is reflow-soldered to a printed circuit board or the like, the thermal properties of the portion to be soldered are unknown. This is because it is difficult to estimate a thermal property value of a part of the electronic component, and the thermal property value also depends on the mounting density of the electronic component. As a result, it has been difficult to grasp the temperature change at the soldered portion on the printed circuit board. In the present embodiment, a thermal property value of the portion to be soldered is obtained.

Hereinafter, description will be made with reference to the flowchart of FIG.
I do. First, in step S201, the first embodiment
In the same manner as described above, a test member 10 having a thermal property value
Convection heat transfer, which is a value indicating the heating characteristics of the heating furnace 1
Coefficient h_i, Infrared emissivity ε_i, View factor F_iTo determine.
At this time, the parameter variable in the first embodiment is the first
Of the first embodiment.
Temperature T of member, surface area A, volume v, density ρ, specific heat c, red
The external ray absorption rate α and the time t are each referred to as T in the present invention. ₁, A₁,
v₁, Ρ₁, C₁, Α₁, T. And in the present invention
A first numerical analysis is performed.

Next, in step S202, the temperature change at each part of the printed circuit board as the object to be heated is measured. In the present embodiment, the temperature changes of the chip resistance land, the QFP land, and the inductor land on the printed circuit board were measured. Hereinafter, this temperature change is referred to as an actually measured temperature change. FIG. 7 shows the result of this actually measured temperature change. In the figure, white circles indicate the temperature of the chip resistor lands, black circles indicate the temperatures of the QFP lands,
The white triangle indicates the temperature change of the inductor land. Further, in FIG. 7 shows a hot air temperature T ∞ _i in the upper and lower surfaces of the object to be heated, each by a chain line and a thick line.
Incidentally, the hot air temperature T ∞ _i of the lower surface shows only a portion different from the hot-air temperature T ∞ _i at the top surface.

Next, the temperature change of each land is obtained by a numerical analysis (second numerical analysis) using a physical model. At this time, the convection heat transfer coefficient h _i , the infrared emissivity ε _i , and the view factor F _i obtained in step S201 are used. Then, in step S203, the value of A ₂ / ρ ₂ c ₂ v ₂ is appropriately defined as the simulated heat capacity of each land of the printed circuit board.

Next, in step S204, the differentiation method
Equation, dT_Two/ Dt = A_Two/ Ρ_Twoc_Twov _Two・ ｛H_i(T∞_i−
T_Two) + Α_Twoε_iF_i(T_hi ^Four-T_Two ^FourUsing A), A_Two/ Ρ
_Twoc_Twov_TwoAnd α_TwoAnd the parameter variable (the second parameter
Number), the temperature change of each land in each heating area
Performs a numerical operation for conversion. And the steps of the first embodiment
In step S205, the measurement is performed in the same manner as in step S104.
Steps should be taken as appropriate to minimize the difference between the fixed and calculated values.
Returning to step S203, the simulation heat capacity A_Two/ Ρ_Twoc_Twov_TwoWhen
α_TwoAdjust the value of.

In this way, the optimum simulated heat capacity is calculated. FIG. 7 shows a temperature change using the optimum simulated heat capacity. The solid line is the temperature change of the chip resistance land, the broken line is the temperature change of the QFP land, and the dotted line is the temperature change of the inductor land. As shown in this figure,
The measured temperature changes indicated by white circles, black circles, and white triangles and the calculated temperature changes could be matched with considerable accuracy.

Since the thermal physical properties (simulated heat capacity) of each part of the printed circuit board were clarified in this manner, the next time the conditions of the heating furnace 1 were changed,
If the heating characteristics are known, the temperature change of each part on the printed circuit board can be easily obtained by using the above differential equation.

(Other Embodiments) In the above-described second embodiment, the temperature change at the measurement point is obtained. However, if the relationship between the heat capacity of the measurement point and other parts on the printed circuit board is known, , Temperature changes in other parts can also be obtained.

In each of the above embodiments, the heating furnace 1 is virtually divided and numerical analysis is performed for each of the i-th heating regions. However, if not necessary, the heating furnace 1 may not be virtually divided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a heating furnace.

FIG. 2 is a schematic diagram of a test member used in the first embodiment.

FIG. 3 is a flowchart relating to a method of obtaining a heating characteristic of a heating furnace.

FIG. 4 is a graph showing a temperature change according to the first embodiment.

FIG. 5 is a graph showing a temperature change in another example of the first embodiment.

FIG. 6 is a flowchart relating to a method of obtaining a thermal physical property value of a heated object.

FIG. 7 is a graph showing a temperature change according to the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating furnace, 2 ... Heating machine (heating means), 4 ... Chain (conveying means), 10 ... Test member.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 31/02 310 B23K 31/02 310F H05K 3/34 507 H05K 3/34 507K 512 512A

Claims (4)

[Claims] 1. A heating furnace (1) provided with a heating means (2) and a conveyance means (4), wherein the heating means is moved in the heating furnace by the conveyance means. In the heating furnace heating evaluation method for heating the object to be heated, a test member (10) having a clear thermal property value is prepared, and the test member is heated while being moved in the heating furnace. Measuring the time change of the temperature of the member, performing a numerical analysis on the temperature and the time of the test member using the thermal properties of the test member with the heating characteristic of the heating furnace as a parameter variable; And determining the parameter variable such that a deviation between the temperature change of the test member and the measured temperature change of the test member is minimized. As the heating temperature according to claim 2, wherein said heating means using the temperature T∞ by temperature T _h and hot air convection by an infrared heater, a thermal physical property value of the test member, the density [rho, specific heat c, the infrared absorptivity α Using the convection heat transfer coefficient h, infrared emissivity ε, and view factor F as the parameter variables, the temperature of the test member is T, the surface area is A, and the volume is v,
The time is represented by t, and the numerical analysis is performed by a differential equation, dT / dt = A / ρcv
· {H (T∞-T) + αεF (T h 4 -T 4)} heating method for evaluating the heating furnace according to claim 1, characterized in that with. 3. A heating furnace (1) provided with a heating means (2) and a transport means (4), wherein the heating means is moved in the heating furnace by the transport means by the transport means. In the method for estimating the temperature of the object to be heated when heating the object to be heated, a test member (10) having a clear thermal property value is prepared, and the test member is heated while being moved in the heating furnace. Measuring the time change of the temperature of the test member, the heating characteristics of the heating furnace as a first parameter variable,
Using the thermal properties of the test member, performing a first numerical analysis on the temperature and time of the test member, the temperature change of the test member by the first numerical analysis, and the measured test member The first parameter variable is determined so that the deviation from the temperature change is minimized, and the object to be heated whose physical properties are unknown is moved while being moved in the heating furnace, so that the object to be heated is heated. Measuring the temporal change of the temperature of the body, using the determined first parameter variable as a second parameter variable with the thermal physical property value of the heated object, as a second parameter variable, with respect to the temperature and time of the heated object, The second parameter variable is determined such that the deviation between the temperature change of the heated object by the second numerical analysis and the measured temperature change of the heated object is minimized. The thermal object of the determined object to be heated Temperature prediction method of the heated body and obtains the temperature change of the heated object by using the values. As the heating temperature according to claim 4, wherein said heating means using the temperature T∞ by temperature T _h and hot air convection by an infrared heater, a thermal physical property value of the test member, the density [rho _1,
Using the specific heat c ₁ , the infrared absorptance α ₁ , the convective heat transfer coefficient h, the infrared emissivity ε, and the form factor F as the first parameter variables, the temperature of the test member is T ₁ , and the surface area is A ₁ , The volume is v ₁ , the time is t, and the first numerical analysis is a differential equation, dT ₁ / dt = A _{1
/ Ρ 1 c 1 v 1 ·} {h (T∞-T 1) + α 1 εF (T h 4 -T 1
⁴ ) The temperature is T ₂ , the surface area is A ₂ , the volume is v ₂ , the time is t, the time is t, and the second parameter variable is
Using A ₂ / ρ ₂ c ₂ v ₂ and α ₂ , the second numerical analysis is performed using a differential equation, dT ₂ / dt = A _{2
/ Ρ 2 c 2 v 2 ·} {h (T∞-T 2) + α 2 εF (T h 4 -T 2
⁴ ) The method according to claim 3, wherein the method is performed by using｝.