JP2016188827A - Temperature measuring device, heater for plating steel plate, pressing device for plating steel plate, method for heating plating steel plate, and method for pressing plating steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature measuring device that can measure the temperature of a plating steel plate while suppressing influence due to variations in the emissivity of the plating steel plate at heating.SOLUTION: A temperature measuring device 4 includes: a reflecting member 6 facing a surface 1a of a plating steel plate 1 and having a reflecting surface 61 reflecting a light emitted from the plating steel plate and an opening 62 in the reflecting surface; and detection means 7 detecting the temperature of the plating steel plate based on the amount of light having entered the opening from the direction of the plating steel plate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a temperature measuring device, a plated steel plate heating device, a plated steel plate pressing device, a plated steel plate heating method, and a plated steel plate pressing method.

  2. Description of the Related Art In recent years, various steel plate processing techniques have been developed along with the increase in strength of thin steel plates aimed at improving fuel efficiency and safety performance by reducing the weight of automobiles. As one of them, there is a hot press technology that can obtain a high-strength steel plate excellent in workability by hot-pressing a steel plate heated at high temperature and simultaneously quenching. In order to form at a high temperature, it is necessary to heat the steel plate to an appropriate temperature, and as a heating method, an electric heating method that can quickly reach the target temperature from the viewpoint of productivity is often used. Further, as a heating control method, a method of predetermining a current / voltage pattern by limiting the size of the steel type and the steel plate, and heating to a target temperature using the pattern (see Patent Document 1), or a steel plate during heating There are methods to measure and control the temperature of In the latter case, measurement with a non-contact radiation thermometer is desirable in consideration of productivity.

  In order to exclude the influence of the emissivity fluctuation of the plated steel sheet, there is a method of measuring temperature by measuring at multiple wavelengths and using the relationship (see Patent Document 2). As a representative method, there is a method of measuring radiated light at two wavelengths, calculating the light quantity ratio, and using a theoretical curve to correspond to the temperature.

JP 2011-82006 A JP-A-5-231945

  The technique of Patent Document 1 has a problem that the current voltage pattern must be experimentally derived each time depending on the steel type and the size of the steel plate, resulting in low productivity. In addition, since the variation in shape and size of the steel sheet becomes a temperature error as it is, there is a problem that the accuracy with respect to the target temperature is often insufficient.

  In the technique of Patent Document 2, unlike Patent Document 1, temperature measurement and control are performed during heating. By the way, steel sheets used in hot press technology are often subjected to surface treatment for the purpose of preventing surface oxidation during quenching and improving corrosion resistance. The change causes emissivity fluctuation. For this reason, when an attempt is actually made to measure with a radiation thermometer, the ratio of the emissivity between the two wavelengths often changes due to melting of the surface plating, and a large error occurs in the measured value. Even if the emissivity of the plated steel sheet fluctuates during heating, it is desirable that the temperature of the plated steel sheet can be accurately measured while suppressing the influence of the fluctuation of the emissivity.

  An object of the present invention is to provide a temperature measuring device capable of measuring the temperature of a plated steel plate while suppressing the influence of fluctuations in the emissivity of the plated steel plate during heating, a heating device for the plated steel plate, a press device for the plated steel plate, and a plated steel plate. And a method of pressing a plated steel sheet.

  The temperature measuring device of the present invention is disposed opposite to the surface of the plated steel plate, has a reflective surface that reflects light emitted from the plated steel plate, and a reflective member having an opening formed in the reflective surface; Detecting means for detecting the temperature of the plated steel sheet based on the amount of light incident on the opening from the plated steel sheet side.

  In the temperature measuring device, it is preferable that the shape of the reflecting surface is a concave shape.

In the temperature measuring device, when the emissivity of the plated steel sheet varies in a range of ε ₁₁ or more and ε ₁₂ or less according to a temperature change, the area S ₁ of the orthogonal projection of the reflecting surface on the surface of the plated steel sheet, The total area S ₃ of the area connecting the outer edge of the reflecting surface and the outer edge of the orthographic projection and the area of the opening, the area S _{2 of} the reflecting surface, and the reflectance r _{2 of the} reflecting surface is [several It is preferable to measure the temperature by satisfying [1] and [Equation 2] so that the apparent emissivity of the plated steel sheet is ε ₁ ^* or more and ε ₂ ^* or less.

  The temperature measuring device further includes a moving means for moving the reflecting member relative to the plated steel sheet in a direction parallel to the surface, and the temperature of the plated steel sheet is adjusted while moving the reflecting member by the moving means. It is preferable to detect.

  In the temperature measuring apparatus, it is preferable that the moving unit moves the reflecting member at a moving speed equal to or higher than a lower limit speed determined from a temperature detection tolerance and a heat removal amount of the plated steel sheet.

  A device for heating a plated steel sheet according to the present invention includes the above temperature measuring device and a heating device for heating the plated steel plate, and heats the plated steel plate to a predetermined temperature based on a temperature detected by the temperature measuring device. It is characterized by that.

  In the heating apparatus for the plated steel sheet, it is preferable that the plated steel sheet is heated by the heating apparatus at a temperature increase rate equal to or higher than a lower limit value determined from a temperature detection tolerance and a heat removal amount of the plated steel sheet.

  The plated steel sheet pressing apparatus of the present invention comprises the above-described plated steel sheet heating apparatus, and press working means for pressing the plated steel sheet heated to the predetermined temperature by the plated steel sheet heating apparatus. To do.

  The method for heating a plated steel sheet according to the present invention reflects light radiated from the plated steel sheet and makes the reflecting surface having an opening face the surface of the plated steel sheet and enters the opening from the plated steel sheet side. A detection step of detecting the temperature of the plated steel plate based on the amount of light; and a heating step of heating the plated steel plate to a predetermined temperature based on the temperature detected in the detection step. .

  In the method for heating a plated steel sheet according to the present invention, it is preferable that in the detection step, the temperature is detected while the reflecting surface is moved relative to the plated steel sheet in a direction parallel to the surface.

  In the method for heating a plated steel sheet according to the present invention, it is preferable that in the detection step, the reflecting surface is moved at a moving speed equal to or higher than a lower limit speed determined from an error in temperature detection and a heat removal amount of the plated steel sheet.

  In the method for heating a plated steel sheet according to the present invention, in the heating step, the plated steel sheet is preferably heated at a temperature increase rate equal to or higher than a lower limit value determined from a temperature detection tolerance and a heat removal amount of the plated steel sheet.

  The method for pressing a plated steel sheet according to the present invention includes the method for heating the plated steel sheet, and a pressing process for pressing the plated steel sheet after the temperature detected in the detection step reaches the predetermined temperature. And

  A temperature measuring device according to the present invention is disposed so as to face a surface of a plated steel plate, has a reflective surface that reflects light emitted from the plated steel plate, and an opening formed in the reflective surface, and plating. Detecting means for detecting the temperature of the plated steel sheet based on the amount of light incident on the opening from the steel sheet side. By disposing the reflective surface opposite to the surface of the plated steel plate, multiple reflection of the emitted light occurs between the surface of the plated steel plate and the reflective surface, and the apparent emissivity increases. Thereby, when the actual emissivity of the plated steel sheet changes during heating, the apparent emissivity change degree becomes smaller than the actual emissivity change degree. Therefore, according to the temperature measuring device concerning the present invention, there is an effect that the temperature of the plated steel sheet can be measured while suppressing the influence due to the change in the emissivity of the plated steel sheet during heating.

FIG. 1 is a schematic configuration diagram of a plated steel plate pressing apparatus according to an embodiment. FIG. 2 is a diagram illustrating a temperature measurement device according to the embodiment. FIG. 3 is a perspective view of the reflecting member and the plated steel plate according to the embodiment. FIG. 4 is a diagram showing the relationship between the lift-off distance and the apparent emissivity. FIG. 5 is a diagram showing the apparent emissivity when the lift-off distance is 0 mm. FIG. 6 is a diagram showing the apparent emissivity when the lift-off distance is 1 mm. FIG. 7 is a diagram showing the apparent emissivity when the lift-off distance is 2 mm. FIG. 8 is a diagram showing the apparent emissivity when the lift-off distance is 3 mm. FIG. 9 is a diagram showing the apparent emissivity when the reflectivity of the reflecting surface is 0.99. FIG. 10 is a diagram showing the apparent emissivity when the reflectance of the reflecting surface is 0.98. FIG. 11 is a diagram showing the apparent emissivity when the reflectivity of the reflecting surface is 0.95. FIG. 12 is a diagram illustrating the apparent emissivity when the reflectivity of the reflecting surface is 0.90. FIG. 13 is a diagram for explaining fluctuations in detection values in a conventional radiation thermometer. FIG. 14 is a diagram for explaining fluctuations in the detection value in the temperature measurement device of the present embodiment. FIG. 15 is a diagram illustrating an example of the arrangement of the temperature measurement devices. FIG. 16 is a diagram illustrating a heating apparatus for a plated steel plate according to a modification of the embodiment.

  Hereinafter, a temperature measuring device, a plated steel plate heating device, a plated steel plate pressing device, a plated steel plate heating method, and a plated steel plate pressing method according to embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

[Embodiment]
The embodiment will be described with reference to FIGS. 1 to 15. The present embodiment relates to a temperature measuring device, a plated steel plate heating device, a plated steel plate pressing device, a plated steel plate heating method, and a plated steel plate pressing method. FIG. 1 is a schematic configuration diagram of a plated steel plate pressing device according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating a temperature measuring device according to the embodiment.

  A plated steel plate pressing apparatus 100 according to this embodiment shown in FIG. 1 presses a plated steel plate 1. The plated steel plate 1 to be processed is, for example, a galvanized steel plate. The plated steel plate pressing device 100 includes a plated steel plate heating device 2 and press working means 3 for pressing the plated steel plate 1.

  The plated steel sheet heating device 2 heats the plated steel sheet 1 to a predetermined temperature based on a temperature detected by a temperature measuring device 4 described later. The press working means 3 presses the plated steel sheet 1 heated to a predetermined temperature by the plated steel heating device 2. The plated steel sheet 1 heated by the plated steel plate heating device 2 is conveyed to the press working means 3 by a conveying means such as a robot arm. The press working means 3 of this embodiment has a punch 31 and a die 32. The press working means 3 presses the plated steel sheet 1 with the punch 31 and the die 32 to form a predetermined shape.

  The plated steel plate heating device 2 includes a temperature measuring device 4 and a heating device 5. As shown in FIG. 2, the temperature measuring device 4 includes a reflecting member 6 and a detection means 7. The reflecting member 6 is disposed to face the plated steel plate 1 and has a reflecting surface 61 that reflects light emitted from the plated steel plate 1 and an opening 62 formed in the reflecting surface 61. The reflecting surface 61 of the reflecting member 6 of the present embodiment has a concave shape. More specifically, the reflecting member 6 of the present embodiment has a hollow cylindrical part 6a and a hollow hemispherical spherical part 6b. The spherical portion 6b is connected so as to close one end of the cylindrical portion 6a. The reflection surface 61 includes a first reflection surface 61a that is an inner surface of the cylindrical portion 6a and a second reflection surface 61b that is an inner surface of the spherical portion 6b. The second reflecting surface 61b has a curved shape in which the cross-sectional radius r decreases as the distance from the cylindrical portion 6a increases. In the present embodiment, the reflecting member 6 is disposed on the upper side of the plated steel plate 1. Thereby, even if the scale of the surface of the plated steel sheet 1 is peeled off during heating, the adhesion to the reflecting surface 61 is suppressed. However, the reflecting member 6 may be disposed below the plated steel plate 1.

  An opening 62 is formed in the reflection surface 61. In the reflecting member 6 of the present embodiment, an opening 62 is formed in the second reflecting surface 61b. The opening 62 is formed at the top of the spherical portion 6 b and coaxially with the central axis of the reflecting member 6. The opening 62 is an emission hole through which the radiated light emitted from the plated steel plate 1 is emitted, and is also a detection hole for detecting the radiated light.

  The detection means 7 detects the temperature of the plated steel sheet 1 based on the amount of light incident on the opening 62 from the plated steel sheet 1 side (internal space of the reflecting member 6). The detection means 7 includes a lens 71, an optical fiber 72, and a detector 73. The lens 71 is disposed in the opening 62. Light incident on the opening 62 from the internal space of the reflecting member 6 is collected on the optical fiber 72 by the lens 71. The optical fiber 72 is a light guide member, and guides light incident from the lens 71 side to the detector 73 of the control device 8. The detector 73 detects the intensity (light quantity) of the light transmitted by the optical fiber 72.

  The control device 8 includes a control unit 81 and a detector 73, and has a function as detection means 7 that detects the temperature of the plated steel sheet 1. Further, the control device 8 has a function as control means for adjusting the heating rate of the heating device 5. The heating device 5 includes electrodes 51a and 51b, a power source 52, and a control unit 81. The heating device 5 increases the temperature of the plated steel sheet 1 by applying a voltage between the electrodes 51 a and 51 b and causing a large current to flow through the plated steel sheet 1. As shown in FIG. 1, the first electrode 51 a is disposed at one end in the width direction (or longitudinal direction) of the plated steel plate 1, and the second electrode 51 b is the other end in the width direction (or longitudinal direction) of the plated steel plate 1. Placed in. The first electrode 51a and the second electrode 51b sandwich the plated steel sheet 1 from both sides in the thickness direction. The electrodes 51a and 51b are connected to a power source 52.

  The power source 52 can adjust the voltage value between the first electrode 51a and the second electrode 51b. The applied voltage by the power source 52 is controlled by the control unit 81. The controller 81 adjusts the applied voltage of the power source 52 so as to increase the temperature of the plated steel sheet 1 at a predetermined heating rate. The control unit 81 adjusts the applied voltage based on the temperature detected by the temperature measuring device 4 so that the rate of increase of the detected temperature becomes the target rate of temperature increase. Moreover, the control part 81 heats the plated steel plate 1 until the temperature detected by the temperature measuring device 4 reaches a predetermined temperature. The predetermined temperature is determined in advance according to the processing content by the press processing means 3. The heating device 5 of this embodiment heats the plated steel plate 1 to 900 [° C.], for example.

  The temperature measuring device 4 is a so-called radiation thermometer, and detects the temperature of the plated steel sheet 1 based on the radiated light emitted from the plated steel sheet 1. The configuration of the temperature measurement device 4 and the temperature detection method of this embodiment will be described. As shown in FIG. 2, the reflecting member 6 is arranged with the reflecting surface 61 facing the surface 1 a of the plated steel plate 1. The reflecting member 6 is arranged so that the central axis of the reflecting member 6 is orthogonal to the surface 1 a of the plated steel plate 1. Further, the reflecting member 6 is disposed with the tip 6c of the cylindrical portion 6a spaced from the surface 1a of the plated steel plate 1 by a predetermined distance L1. In the present specification, the predetermined distance L1 is referred to as a “lift-off distance”.

  The temperature measuring device 4 of the present embodiment multi-reflects light emitted from the plated steel plate 1 between the surface 1 a of the plated steel plate 1 and the reflecting surface 61 when the plated steel plate 1 is heated. The apparent emissivity of the plated steel sheet 1 increases due to the multiple reflection. Thereby, as will be described below, even if the surface properties of the plated steel sheet 1 are changed by heating and the true emissivity changes, the apparent emissivity change degree is relative to the true emissivity change degree. Get smaller. Therefore, the temperature measuring device 4 of the present embodiment can accurately detect the temperature of the plated steel sheet 1 during heating.

The apparent emissivity ε ^* will be described with reference to FIG. FIG. 3 shows a perspective view of the reflecting member 6 and the plated steel sheet 1 during temperature measurement. The amount of reflected light when the emitted light is multiple-reflected can be represented by the areas S ₁ , S ₂ , S ₃ . Here, the area S ₁ is an area of the orthogonal projection 1 b of the reflecting member 6 on the surface _{1 a} of the plated steel plate 1. The area S ₂ is the area of the reflecting surface 61. The opening area S ₃ is the sum of the area S ₃₁ of the gap between the reflecting member 6 and the plated steel plate 1 and the area S ₃₂ of the opening 62 shown in FIG. The area S ₃₁ of the gap is an area of the inner peripheral surface 9 of the virtual wall portion obtained by extending the cylindrical portion 6 a of the reflecting member 6 toward the plated steel plate 1. In other words, the area S ₃₁ of the gap is the area of the surface connecting the outer edge 1c of the outer edge 61c and orthogonal projection 1b of the reflecting surface 61 (curved surface when orthogonal projection 1b is a curve). Area _{S 31} of the gap is the area multiplied by the lift-off distance L1 in the circumferential length (circumferential length of the orthogonal projection 1b) of the outer edge 61c of the reflecting surface 61.

In order to simplify the reflection model, S ₂ / (S ₂ + S ₃ ) of the reflected light reflected on the surface 1 a of the plated steel sheet 1 proceeds toward the reflecting surface 61 of the reflecting member 6, and the remaining S ₃ It is assumed that / (S ₂ + S ₃ ) proceeds toward the external space of the reflecting member 6. Note that the light that travels through the opening 62 toward the external space is detected by the detection means 7. Further, of the reflected light reflected by the reflecting surface 61, S ₁ / (S ₁ + S ₃ ) travels toward the orthogonal projection 1b, and S ₃ / (S ₁ + S ₃ ) travels toward the external space. A part of the light reflected by the reflecting surface 61 travels toward another portion of the reflecting surface 61, but the shape of the reflecting surface 61 is determined so that the amount thereof is negligible. In addition, it is assumed that the light once emitted to the external space does not return to the orthographic projection 1b or the reflecting surface 61.

The reflected light quantity of light radiated from the plated steel sheet 1 and reflected on the surface 1a at the nth multiple reflection is assumed to be In. The nth reflected light amount In is calculated by the following [Equation 3]. Here, T: temperature of the surface 1a of the plated steel sheet 1, Tb (T): black body radiation energy at the temperature T, ε ₁ : emissivity of the surface 1a of the plated steel sheet 1, r ₁ : surface 1a of the plated steel sheet 1 Reflectance, r ₂ : Reflectance of the reflecting surface 61. Note that the surface temperature T of the plated steel plate 1 is sufficiently higher than the temperature of the internal space of the reflecting member 6, and the amount of light emitted from the reflecting member 6 is negligible.

The energy E of light incident on the opening 62 from the plated steel sheet 1 side and detected by the detection means 7 is expressed by the following [Equation 4] as an infinite series sum of multiple reflections.

Further, from Kirchhoff's law, the following formula (1) is established. Therefore, the apparent emissivity ε ^* in the amount of light obtained from the optical fiber 72 is expressed by the following [Equation 5].
r ₁ = 1−ε ₁ (1)

FIG. 4 shows a simulation result and an actual measurement value of the apparent emissivity ε ^* . In FIG. 4, the horizontal axis represents the lift-off distance L1, and the vertical axis represents the apparent emissivity ε ^* . The reflectance r ₂ of the reflecting surface 61 is 0.89 and the emissivity ε ₁ of the surface 1a of the plated steel sheet 1 is 0.4. The spherical portion 6b of the reflecting member 6 is a hemispherical shape having an inner diameter of 25 [mm], and the opening 62 is a circular shape having a radius of 4 [mm]. In FIG. 4, the curve is the apparent emissivity ε ^* calculated by the above [Equation 5], and the point plot is the emissivity obtained by actual measurement. The actual measurement value is an apparent emissivity value obtained from the surface temperature of the plated steel sheet 1 measured by a thermocouple and the amount of light detected by the radiation thermometer with the reflection member 6 installed. The detection target wavelength of the radiation thermometer is 900 [nm]. As shown in FIG. 4, the simulation and the actual measurement values are in good agreement.

As shown in FIG. 4, according to the temperature measuring device 4 of the present embodiment, the value of the apparent emissivity ε ^* is larger than the emissivity ε ₁ (= 0.4) of the surface 1a of the plated steel plate 1. Become. The apparent emissivity ε ^* changes according to the lift-off distance L1. As the lift-off distance L1 increases, the apparent emissivity ε ^* increases.

5 to as described with reference to FIG. 8, it is possible to reduce the detection error when the emissivity epsilon ₁ is changed in accordance with lift-off distance L1 decreases. In FIGS. 5 through 8, the horizontal axis represents the emissivity epsilon ₁ of the surface 1a of the plated steel plate 1, the vertical axis represents the emissivity of the apparent epsilon ^*. The lift-off distance L1 increases in the order from FIG. 5 to FIG. Specifically, the lift-off distance L1 is 0 [mm] in FIG. 5, 1 [mm] in FIG. 6, 2 [mm] in FIG. 7, and 3 [mm] in FIG. In the simulation shown in FIGS. 5 to 8, the reflectance r ₂ of the reflecting surface 61 is 0.99. In each figure, the curve showing the relationship between the emissivity ε ₁ and the apparent emissivity ε ^* is convex upward (apparent emissivity ε ^* > actual emissivity ε ₁ ). Further, as the lift-off distance L1 increases, the magnification (ε ^* / ε ₁ ) of the apparent emissivity ε ^* with respect to the actual emissivity ε ₁ increases.

In the case of the lift-off distance L1 = 2 [mm] shown in FIG. 7, when the emissivity ε1 of the plated steel sheet ₁ is 0.5, the apparent emissivity ε ^* is 0.81. Therefore, in the range of emissivity ε ₁ of 0.5 or more, the apparent emissivity ε ^* value changes in the range of 0.81 or more. Suppose that the emissivity ε ₁ of the plated steel sheet 1 is halved from 1.0 to 0.5 due to the temperature rise of the plated steel sheet 1. In this case, in the conventional radiation thermometer, the detected light quantity is halved. On the other hand, in the temperature measurement device 4 of the present embodiment, the apparent emissivity ε ^* is only lowered from 1.0 to 0.81, and the temperature measurement error is reduced as compared with the conventional case. Further, in the case of the lift-off distance L1 = 0 shown in FIG. 5, a emissivity epsilon ^* 0.95 of apparent when the actual emissivity epsilon ₁ is 0.5. Thus, in accordance with to reduce the lift-off distance L1, to reduce the effect on the actual emissivity of the changes in emissivity epsilon ₁ apparently epsilon ^*, it is possible to reduce the measurement error of the temperature.

Next, the relationship between the reflectance r ₂ of the reflecting surface 61 and the apparent emissivity ε ^* will be described. 9 to FIG. 12, the horizontal axis represents the emissivity epsilon ₁ of the surface 1a of the plated steel plate 1, the vertical axis represents the emissivity of the apparent epsilon ^*. In the order from FIG. 9 to FIG. 12, the reflectance r ₂ of the reflecting surface 61 decreases. Specifically, the reflectance r ₂ of the reflecting surface 61 is 0.99 in FIG. 9, 0.98 in FIG. 10, 0.95 in FIG. 11, and 0.90 in FIG. In the simulation shown in FIGS. 9 to 12, the lift-off distance L1 is 1 [mm]. As the reflectance r ₂ of the reflecting surface 61 increases, the magnification (ε ^* / ε ₁ ) of the apparent emissivity ε ^* with respect to the actual emissivity ε ₁ increases.

In the case of the reflectivity r ₂ = 0.95 shown in FIG. 11, when the actual emissivity ε ₁ is 0.5, the apparent emissivity ε ^* is 0.84. Even when the reflectivity r ₂ = 0.90 shown in FIG. 12, if the actual emissivity ε ₁ is 0.5 or more, the apparent emissivity ε ^* is 0.81 or more. Therefore, even if the actual emissivity ε ₁ changes due to the temperature rise of the plated steel sheet 1, it can be said that the apparent emissivity ε ^* is hardly affected.

In addition, it is preferable that the fluctuation range of the emissivity ε ₁ of the plated steel sheet 1 according to the temperature change is a range in which the change in the apparent emissivity ε * is small. For example, in FIG. 11, in a range emissivity epsilon ₁ is more than 0.5, the slope of the curve showing the emissivity apparent epsilon _* (percentage change in the emissivity of the apparent epsilon _* to variations in emissivity epsilon ₁₎ is less . To the extent emissivity epsilon ₁ of plated steel sheet 1 varies according to the temperature change, the slope of the curve showing the emissivity apparent epsilon _* is preferably less than 1.

The temperature detection evaluation by the temperature measuring device 4 of the embodiment will be described. The plated steel sheet 1 to be measured is galvanized, and the melting point of the zinc alloy is around 700 [° C.]. It is assumed that the emissivity ε _{1 on} the surface of the plated steel sheet 1 changes from 0.8 to 0.5 by melting the zinc alloy beyond the melting point. The wavelength of the monochromatic radiation thermometer is 900 [nm], the temperature measurement region is 600 [° C.] or more, and the emissivity is set to 0.8. FIG. 13 shows the relationship between the temperature T of the plated steel sheet 1 and the radiance when the emissivity ε ₁ of the plated steel sheet 1 is 1.0, 0.8, and 0.5, respectively. The amount of radiant light is calculated using a general Planck equation. The spectral radiant energy u is calculated by the following [Equation 6]. Here, h is the Planck constant, c is the speed of light, k is the Boltzmann constant, and λ is the wavelength.

It is assumed that the actual emissivity ε ₁ of the plated steel sheet 1 decreases from 0.8 to 0.5 due to the temperature rise while the emissivity is set to 0.8 in the radiation thermometer. As can be seen from FIG. 13, when the temperature T of the plated steel sheet 1 is 800 [° C.], the radiation thermometer shows a temperature 33 [° C.] lower than the true temperature. Further, when the temperature T of the plated steel plate 1 is 700 [° C.], the radiation thermometer shows a temperature 27 [° C.] lower than the true temperature.

FIG. 14 shows an example of measurement by the temperature measuring device 4 of the present embodiment. The lift-off distance L1 of the reflection member 6 1 [mm], when the reflectance _{r 2} of the reflecting surface 61 and 0.99, when the emissivity epsilon ₁ of the surface 1a of the plated steel sheet 1 is 0.5, 0.8 In addition, from the above [Equation 5], the apparent emissivity ε ^* is obtained as 0.87 and 0.96, respectively. FIG. 14 shows the relationship between the temperature T of the plated steel sheet 1 and the radiance when the emissivity ε ₁ is 1.0, 0.96, and 0.87. When emissivity epsilon ₁ of plated steel sheet 1 is changed from 0.8 to 0.5, emissivity apparent epsilon ^* changes from 0.96 to 0.87. Therefore, when the emissivity ε is set to 0.96 in the radiation thermometer, if the temperature T of the plated steel sheet 1 is 800 [° C.], the detection error is 7 [° C.], and the temperature T of the plated steel sheet 1 is 700 [° C.]. [° C.], the detection error is 6 [° C.]. Therefore, the temperature measuring device 4 of the present embodiment having the reflecting member 6 can reduce the detection error of the temperature T to less than a quarter compared to the conventional case.

Here, when the value of the emissivity ε ₁ of the plated steel sheet 1 corresponding to the temperature change is known in advance, the apparent emissivity ε ^* can be designed to change within a desired range. For example, it is assumed that the emissivity ε ₁ of the plated steel sheet 1 varies in the range of ε ₁₁ or more and ε ₁₂ or less while being heated to the target temperature by the heating device 5. In this case, when it is desired to set the apparent emissivity ε ^* to be equal to or greater than ε ₁ ^* , the areas S ₁ , S ₂ , S ₃ and the reflectance r ₂ may be determined so that the above [Equation 1] is satisfied. .

If the apparent emissivity ε ^* is desired to be equal to or less than ε ₂ ^* , the areas S ₁ , S ₂ , S ₃ and the reflectance r ₂ may be determined so that the above [Equation 2] is satisfied.

  In addition, the radiation light from the plated steel plate 1 is reflected toward the plated steel plate 1 by the reflecting member 6, so that radiation heat from the surface 1 a is suppressed at a portion facing the reflecting member 6. Accordingly, if a temperature difference occurs between the portion facing the reflecting member 6 and the other portion, the temperature of the plated steel sheet 1 may not be measured correctly. Therefore, it is preferable to quickly raise the temperature of the plated steel sheet 1 to the target temperature so as not to be affected by the suppression of heat removal. In other words, it is preferable to raise the temperature increase rate to the target temperature by sufficiently increasing the temperature increase rate compared to the heat removal rate.

The amount of heat removal inhibition per unit area of the plated steel sheet 1 by the reflecting member 6 is evaluated. For simplicity, the temperature rise rate constant value (alpha), considering that heating from room temperature T _o to the target temperature T _1. The emissivity of the steel sheet surface epsilon _o, Stefan Boltzmann constant sigma, the heating time is t _o, heat removal Q per unit area is represented by the following [Equation 7].

When the above [Equation 7] is integrated, the following [Equation 8] is obtained.

Thus, heat removal amount per unit time during the heating is proportional to the heating time t _o, it is possible reduce heat loss inhibiting effect by shortening the heating time t _o. For example, the temperature decrease in the size of the surface 1a during heating according to the heat loss quantity Q may be determined heating time t _o to be a predetermined value or less. The predetermined value is determined based on a tolerance for temperature detection. For example, it is assumed that a temperature difference Tdif occurs between the orthogonal projection 1b and its peripheral part due to the heat removal inhibition by the reflecting member 6. It is assumed that the temperature difference Tdif can be allowed up to 5 [° C.] based on the temperature detection tolerance. In this case, it is preferable to determine the upper limit of the reflective member 6 and the temperature decrease amount corresponding to the dissipation heat quantity Q in not facing the portion 5 [° C.] heating time as to become less t _o of the surface 1a. In this way, even if heat removal is completely obstructed at the portion facing the reflecting member 6, the temperature detection error can be suppressed within the allowable error range. As a result, the plated steel sheet 1 can be heated at a temperature increase rate α equal to or higher than the lower limit determined from the tolerance of temperature detection and the heat removal amount Q (heat removal speed) of the plated steel sheet 1 being heated.

As described above, the temperature measurement device 4 according to the present embodiment includes the reflecting member 6 and the detection unit 7. The reflecting member 6 is disposed so as to face the surface 1 a of the plated steel plate 1, and has a reflecting surface 61 that reflects light emitted from the plated steel plate 1, and an opening 62 formed in the reflecting surface 61. The detecting means 7 detects the temperature of the plated steel sheet 1 based on the amount of light incident on the opening 62 from the plated steel sheet 1 side. By arranging the reflecting surface 61 of the reflecting member 6 so as to face the plated steel plate 1, the apparent emissivity ε ^* of the plated steel plate 1 increases due to multiple reflection. Thereby, even if emissivity changes by the change of the surface property of the plated steel plate 1 during heating, the change of the light quantity detected by the detection means 7 is suppressed. Therefore, the temperature measuring device 4 of this embodiment can detect the temperature of the plated steel plate 1 to be heated with high accuracy.

Moreover, in the temperature measuring device 4 of this embodiment, the shape of the reflective surface 61 is a concave shape. Thereby, the multiple reflection between the reflective surface 61 and the surface 1a of the plated steel plate 1 can be promoted, and the apparent emissivity ε ^* can be improved. The shape of the reflecting surface 61 is not limited to a hemispherical shape. For example, the reflecting surface 61 may be a parabolic curved surface such as a parabolic antenna or a concave surface as a whole by combining a number of flat surfaces. Good. Further, the reflecting surface 61 may be a flat surface.

The temperature measuring device 4 of this embodiment, when the emissivity of the coated steel sheet 1 varies in a range of epsilon ₁₁ or epsilon ₁₂ below according to a temperature change, the positive reflecting surface 61 at the surface 1a of the plated steel sheet 1 The area S _{1 of} the projection 1b, the total area S ₃ of the area connecting the outer edge 61c of the reflecting surface 61 and the outer edge 1c of the orthographic projection 1b and the area of the opening 62, the area S _{2 of} the reflecting surface 61, and the reflection When the reflectance r ₂ of the surface 61 satisfies the above [Equation 1] and [Equation 2], the apparent emissivity of the plated steel sheet 1 is set to ε ₁ ^{* and not} more than ε ₂ ^* , and the temperature is measured. Therefore, the apparent emissivity ε * can be set in a desired range, and the temperature of the plated steel sheet 1 to be heated can be detected with high accuracy.

  The plated steel plate heating device 2 of the present embodiment includes a temperature measuring device 4 and a heating device 5 for heating the plated steel plate 1. The plated steel sheet heating device 2 heats the plated steel sheet 1 to a predetermined temperature based on the temperature detected by the temperature measuring device 4. Since the detection accuracy of the temperature measuring device 4 is high, the temperature of the plated steel sheet 1 can be controlled to a predetermined temperature with high accuracy by feedback control.

  The plated steel plate pressing apparatus 100 according to this embodiment includes a plated steel plate heating device 2 and press working means 3 that presses the plated steel plate 1 heated to a predetermined temperature by the plated steel plate heating device 2. . Since the temperature control of the plated steel plate 1 is performed with high accuracy by the heating device 2 for the plated steel plate, it is possible to perform hot stamping of the plated steel plate 1 at an appropriate temperature with high quality.

The method for heating a plated steel sheet according to the present embodiment includes a detection step and a heating step. The detecting step reflects light emitted from the plated steel sheet 1 and causes the reflecting surface 61 having the opening 62 to face the surface 1a of the plated steel sheet 1 so that light incident on the opening 62 from the plated steel sheet 1 side is reflected. This is a step of detecting the temperature of the plated steel sheet 1 based on the amount of light. The heating process is a process of heating the plated steel sheet 1 to a predetermined temperature based on the temperature detected in the detection process. In the detection step, the reflected light 61 is reflected multiple times between the reflecting surface 61 and the surface 1a of the plated steel plate 1, thereby improving the apparent emissivity ε ^* and improving the temperature detection accuracy. Therefore, the heating method of the plated steel plate of this embodiment can control the temperature of the plated steel plate 1 with high accuracy.

  Moreover, the heating method of the plated steel plate of this embodiment heats the plated steel plate 1 at a temperature increase rate equal to or higher than a lower limit value (allowable) determined (allowed) from the tolerance of temperature detection and the heat removal amount of the plated steel plate 1 in the heating process. . As a result, the temperature detection error can be suppressed within the allowable error range.

  The method for pressing a plated steel sheet according to the present embodiment includes the above-described heating method for the plated steel sheet and a pressing process for pressing the plated steel sheet 1 after the temperature detected in the detection process reaches a predetermined temperature. Since the temperature control of the plated steel sheet 1 is performed with high accuracy in the heating step, it is possible to perform hot stamping of the plated steel sheet 1 with high quality.

  In addition, in the heating apparatus 2 for the plated steel plate, the plated steel plate 1 may be fixed perpendicular to the horizontal plane as shown in FIG. In this way, when the plated steel sheet 1 is heated and the scale peels from the surface 1 a, the peeled scale is difficult to adhere to the reflective surface 61.

From the viewpoint of suppressing radiated light from escaping to the external space of the reflecting member 6, the lift-off distance L1 is preferably zero. However, if the reflecting member 6 is brought into contact with the plated steel sheet 1 while the heating device 5 is energizing the electrodes 51a and 51b, the current distribution changes. For this reason, it is necessary to bring the reflecting member 6 as close as possible without touching the plated steel plate 1. Considering the flapping of the plated steel sheet 1 during heating, a certain amount of lift-off distance L1 is required. Therefore, for example, by increasing the size of the reflecting member 6 in the same lift distance L1, it may be relatively small influence of the gap area S _31. Alternatively, the lift-off distance L1 may be reduced by applying a large tension to the plated steel sheet 1 during energization heating to suppress vibration and fluttering and avoiding a collision between the plated steel sheet 1 and the reflecting member 6.

[Modification of Embodiment]
A modification of the embodiment will be described. FIG. 16 is a diagram illustrating a heating apparatus for a plated steel plate according to a modification of the embodiment. The plated steel sheet heating apparatus 2 according to the modification is different from the plated steel sheet heating apparatus 2 of the above embodiment in that it includes a moving unit 10 that moves the reflecting member 6. The temperature measuring device 4 of the present modification detects the temperature of the plated steel sheet 1 while moving the reflecting member 6 by the moving means 10. Thereby, the degree of suppression of heat removal by the reflection member 6 can be reduced, and the temperature detection accuracy can be improved.

The moving means 10 moves the reflecting member 6 relative to the plated steel plate 1 in a direction parallel to the surface 1 a of the plated steel plate 1. The moving means 10 moves the reflecting member 6 by a force generated by a power source such as a motor, for example. It is preferable that the moving means 10 can move the reflecting member 6 in both the width direction and the longitudinal direction of the plated steel sheet 1. When the heating device 5 is heating the plated steel plate 1, by measuring the temperature while moving the reflecting member 6 relative to the plated steel plate 1, the degree to which heat removal from the surface 1 a is suppressed is reduced. For example, when the length of the reflecting member 6 in the moving direction by the moving means 10 is L and the moving speed is V, the time facing the reflecting member 6 in each measurement portion of the surface 1a is L / V. Therefore, the heating time _{t o} may be divided _Vt o / L.

The moving speed of the reflecting member 6 can be determined as follows, for example, based on the error effect due to the suppression of heat removal. The temperature _{T o} of the heating starting plated steel 1 30 [° C.], the target temperature _{T 1 900 [℃], 2} [mm] thickness d of the plated steel sheet, the specific heat c 0.435 [J / g · K], density ρ is 6.83 [g / cm ³ ], emissivity ε is 0.8, and Boltzmann constant σ is 5.67 × 10 ⁻⁸ . As the temperature of the plated steel sheet 1 is high, since the heat removing amount increases due to radiation, to calculate the heat removal amount immediately before reaching the target temperature T _1. A temperature change amount ΔT [° C./s] per unit time due to heat removal in the vicinity of the target temperature T ₁ is calculated as in the following [Equation 9].

Here, it is assumed that the target error δ is within 5 [° C.] and the length L in the moving direction of the reflecting member 6 is 40 [mm]. In the vicinity of the target temperature, the time Δt during which the reflecting member 6 faces an arbitrary point on the surface 1a and the moving speed v [mm / s] of the reflecting member 6 must satisfy the following [Equation 10]. . That is, the lower limit speed of the reflecting member 6 in this case is 143.87 [mm / s].

  From the above [Equation 10], for example, if the reflecting member 6 is moved at a speed of 150 [mm / s] or more, the temperature measurement error can be kept within 5 [° C.]. When the difference in temperature after measurement is within the target error δ without moving the reflecting member 6, the total temperature change is integrated by integrating the temperature change ΔT due to heat removal from the initial temperature until reaching the target temperature. Find the amount. The lower limit of the temperature increase rate α by the heating device 5 is determined so that the total temperature change amount is within the target error δ.

  As described above, the temperature measuring device 4 of the present modification has the moving means 10 for moving the reflecting member 6 relative to the plated steel plate 1 in a direction parallel to the surface 1a, and is reflected by the moving means 10. The temperature of the plated steel sheet 1 is detected while moving the member 6. That is, in the detection process, the temperature measuring device 4 detects the temperature while moving the reflecting surface 61 relative to the plated steel plate 1 in a direction parallel to the surface 1a. Therefore, the temperature measuring device 4 of the present modification can suppress the occurrence of a heat removal bias (surface temperature bias) on the surface 1a, and can detect the temperature of the plated steel sheet 1 with high accuracy.

  Further, the moving means 10 of the temperature measuring device 4 of the present modification moves the reflecting member 6 at a moving speed equal to or higher than the lower limit speed determined from the temperature detection tolerance and the amount of heat removed from the plated steel sheet 1. That is, in the detection process, the temperature measuring device 4 moves the reflecting surface 61 at a moving speed equal to or higher than the lower limit speed determined from the temperature detection tolerance and the amount of heat removed from the plated steel sheet 1. Thereby, the temperature detection error can be suppressed within the allowable error range.

  The contents disclosed in the above embodiments and modifications can be executed in appropriate combination.

DESCRIPTION OF SYMBOLS 1 Plated steel plate 1a Surface 1b Orthographic projection 1c Outer edge of orthographic projection 2 Heating device of plated steel plate 3 Press working means 31 Housing 32 Work roll 33 Backup roll 4 Temperature measuring device 5 Heating device 51a First electrode 51b Second electrode 52 Power supply 6 Reflection Member 6a Cylindrical part 6b Spherical part 61 Reflective surface 61a First reflective surface 61b Second reflective surface 61c Outer edge of reflective surface 62 Opening 7 Detection means 71 Lens 72 Optical fiber 73 Detector 8 Control device 81 Control part 9 Virtual wall part 10 Moving means 100 emissivity of the surface area S ₃ opening area epsilon ₁ plated steel orthogonal projection of the area S ₂ reflection surface of the reflection factor S ₁ reflecting surface of the press L1 liftoff distance r ₂ the reflecting surface of the plated steel sheet

Claims (13)

A reflecting member that is disposed to face the surface of the plated steel plate, reflects the light emitted from the plated steel plate, and has an opening formed in the reflecting surface;
Detection means for detecting the temperature of the plated steel sheet based on the amount of light incident on the opening from the plated steel sheet side;
A temperature measuring device comprising: The temperature measuring device according to claim 1, wherein the shape of the reflecting surface is a concave shape. When the emissivity of the coated steel sheet varies in a range of epsilon ₁₁ or epsilon ₁₂ below according to a temperature change, the orthogonal projection of the area S ₁ of the reflecting surface at the surface of the plated steel _sheet, the outer edge of the reflecting surface The total area S ₃ of the area connecting the outer edges of the orthogonal projection and the area of the opening, the area S _{2 of} the reflecting surface, and the reflectance r _{2 of the} reflecting surface are expressed by the following formulas (I) and ( The temperature measurement device according to claim 1 or 2, wherein the temperature measurement is performed by satisfying II) so that the apparent emissivity of the plated steel sheet is ε ₁ ^* or more and ε ₂ ^* or less.

Furthermore, it comprises a moving means for moving the reflecting member relative to the plated steel plate in a direction parallel to the surface,
The temperature measuring device according to any one of claims 1 to 3, wherein the temperature of the plated steel sheet is detected while the reflecting member is moved by the moving means. The temperature measuring apparatus according to claim 4, wherein the moving unit moves the reflecting member at a moving speed equal to or higher than a lower limit speed determined from an error in temperature detection and a heat removal amount of the plated steel sheet. The temperature measuring device according to any one of claims 1 to 5,
A heating device for heating the plated steel sheet;
And heating the plated steel plate to a predetermined temperature based on the temperature detected by the temperature measuring device. The apparatus for heating a plated steel sheet according to claim 6, wherein the heating apparatus heats the plated steel sheet at a temperature increase rate equal to or higher than a lower limit value determined from a temperature detection tolerance and a heat removal amount of the plated steel sheet. A heating apparatus for a plated steel sheet according to claim 6 or 7,
A pressing means for pressing the plated steel sheet heated to the predetermined temperature by the heating device for the plated steel sheet;
An apparatus for pressing a plated steel sheet, comprising: Reflecting the light radiated from the plated steel sheet, with the reflecting surface having an opening opposed to the surface of the plated steel sheet, based on the amount of light incident on the opening from the plated steel sheet side, A detection step for detecting the temperature;
Based on the temperature detected in the detection step, a heating step of heating the plated steel sheet to a predetermined temperature;
A method for heating a plated steel sheet, comprising: The method for heating a plated steel sheet according to claim 9, wherein, in the detecting step, the temperature is detected while the reflective surface is moved relative to the plated steel sheet in a direction parallel to the surface. The said detection process WHEREIN: The said reflective surface is moved by the moving speed more than the minimum speed determined from the tolerance of temperature detection, and the amount of heat removal of the said plated steel plate of the part facing the said reflective surface. Heating method for plated steel sheets. In the heating step, the plated steel sheet is heated at a temperature increase rate equal to or higher than a lower limit value determined from a tolerance of temperature detection and a heat removal amount of the plated steel sheet in a portion facing the reflection surface. The heating method of the plated steel plate according to any one of 11. A method for heating a plated steel sheet according to any one of claims 9 to 12,
And a pressing step of pressing the plated steel plate after the temperature detected in the detecting step reaches the predetermined temperature.

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