Heating control method and heating control device, and heating molding method and heating molding device

Abstract

To heat an object to be heated always stably with a set temperature distribution even if an initial temperature of the object to be heated, a molding device, etc., or the ambient environment is different when the object to be heated is heated with radiant heat from a plurality of heaters.SOLUTION: An object to be heated is heated by a plurality of heaters 11 which generate radiant heat, and the temperature of the object to be heated is controlled to a desired target temperature distribution. Supply energy is imparted to each of the plurality of heaters, and a supply energy distribution is obtained that is set for each of the plurality of heaters in order to heat the object to be heated to a target temperature distribution. The radiant heat corresponding to the supply energy distributions is generated by the plurality of heaters 11, and temperatures at a plurality of places of the object to be heated are measured to find a measured temperature distribution. For each heated area, a difference between the measured temperature distribution and the target temperature distribution is calculated and a correction amount for supply energy is calculated for each heater 11 based upon the difference. The radiant heat corresponding to the corrected energy distribution found by the heaters 11 is generated by the plurality of heaters 11 to heat the object to be heated.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a heating control method, a heating control device, a molding method, and a molding device.

Background Art

[0002] With the recent digitization of the glass molding process, the realization of multi-variety high-speed molding is expected. In glass molding, it is known that the viscosity that changes with the glass temperature affects the quality of the molded product, and in order to realize stable glass molding, it is necessary to accurately control the glass temperature and its temperature distribution.

[0003] In a conventional glass molding machine, glass molded products were produced in a stable environment by continuous production with a constant output of the heater and a constant heating set temperature. However, it takes time for the glass molding machine to reach a stable state, and there are also environmental changes due to the outside air temperature and the like, which have affected the productivity and quality of the molded products.

[0004] Also, in the case of glass molding, even if the output of the heater is set to be constant, the temperature of the glass plate does not become the same and the temperature distribution is also different between the cold state immediately after the start of heating and the hot state during continuous molding in the furnace of the glass molding machine. Thus, in glass molding where the viscosity changes with temperature, the temperature error has a great influence on the molding quality.

[0005] The above is true not only for glass but also for other materials such as steel materials, and accurate control of the heating temperature has been an issue. For example, Patent Document 1 describes a method for controlling the temperature of a steel plate. In this temperature control method, a plurality of divided regions are formed in a heat treatment furnace into which the steel plate is charged, and the shape factor and emissivity are set for each divided region. According to this, when calculating the steel plate temperature using a one-dimensional heat conduction equation, the influence of variations in the shape factor and emissivity in the heat treatment furnace can be suppressed. In that case, the output of the heater is obtained by inversely calculating using the least squares method, associating the heated object and the heater in the radiative heating field with the shape factor. Further, Patent Document 2 describes a method for formulating the relationship between the heated object and the heater in the radiative heating field and controlling the temperature.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the temperature control method of Patent Document 1, instead of controlling the temperature distribution, the steel plate is only taken out of the heat treatment furnace when the preset heat treatment temperature is reached. Further, the shape factor is used when obtaining the relationship between the furnace atmosphere temperature and the steel plate temperature from the thermocouple installed in the furnace and the thermocouple installed in the test steel plate, and the shape factor is not re-entered when estimating and calculating the steel plate temperature from the furnace atmosphere temperature. That is, it is assumed that the conditions do not change between the test time and the actual measurement time. In the temperature control of Patent Document 2, the temperature is measured at only one location, and the temperature distribution is not measured. Further, although the control device of Patent Document 2 includes a plurality of heaters, it does not control each heater individually to control the temperature distribution. Furthermore, PID control is frequently used for general temperature control. However, in a radiation heating field that utilizes radiant heat from a heater, optimal temperature control may not be achievable with normal PID control as it can be affected by disturbances.

[0008] Thus, when the object to be heated is radiantly heated by the heat generation of multiple heaters, there are still many challenges in appropriately setting the output of each heater so that the object to be heated has an ideal temperature distribution.

[0009] Therefore, an object of the present invention is to provide a heating control method, a heating control device, a molding method, and a molding device that can always stably heat to a set temperature distribution even when the initial temperature and the surrounding environment of the object to be heated, the molding device, etc. are different when heating the object to be heated by radiant heat from multiple heaters.

Means for Solving the Problems

[0010] The present invention has the following configuration. (1) A heating control method for heating an object to be heated by a plurality of heaters that generate radiant heat and controlling the temperature of the object to be heated to a desired target temperature distribution, wherein the plurality of heaters are arranged for each of a plurality of heating regions obtained by dividing the object to be heated, supply energy to be applied to each of the plurality of heaters is determined, and a supply energy distribution set for each heater for heating the object to be heated to the target temperature distribution is obtained, radiant heat corresponding to the supply energy distribution is generated from the plurality of heaters to heat the object to be heated, temperatures at a plurality of locations of the heated object to be heated are measured to obtain a measured temperature distribution, a difference between the measured temperature distribution and the target temperature distribution is calculated for each of the heating regions, a correction amount of the supply energy is calculated for each heater based on the difference, a corrected energy distribution obtained by correcting the supply energy for each heater with the correction amount is obtained, radiant heat corresponding to the corrected energy distribution is generated from the plurality of heaters to heat the object to be heated. Heating control method. (2) A movable member is pressed against the heated object heated by the heating control method according to (1) to form a molded body having a desired shape. Heat molding method. (3) A heating control device that heats a heated object by radiant heat and controls the temperature of the heated object to a desired target temperature distribution, A plurality of heaters arranged for each of a plurality of heating regions obtained by dividing the heated object, which generate radiant heat; Supply energy calculation unit that calculates a supply energy distribution that is supply energy applied to each of the plurality of heaters and is set for each heater to heat the heated object to the target temperature distribution; A heater drive unit that generates radiant heat corresponding to the supply energy distribution from the plurality of heaters to heat the heated object; A temperature measurement unit that measures the temperatures at a plurality of locations of the heated object and outputs information on the measured temperature distribution; A difference calculation unit that calculates the difference between the measured temperature distribution and the target temperature distribution for each heating region; A correction amount calculation unit that calculates a correction amount of the supply energy for each heater based on the difference; A correction energy calculation unit that obtains a corrected energy distribution in which the supply energy for each heater is corrected by the correction amount; Comprising The heater drive unit generates radiant heat corresponding to the corrected energy distribution from the plurality of heaters to heat the heated object. Heating control device. (4) The heating control device according to (3), which heats the heated object to a molding temperature, A molding unit that presses a movable member against the heated object heated by the heating control device to mold the heated object; A heat molding device including

Advantages of the Invention

[0011] According to the present invention, when heating an object to be heated by radiant heat from a plurality of heaters, even if the initial temperature of the object to be heated, the molding apparatus, etc. and the ambient environment are different, it is always possible to stably heat to a set temperature distribution.

Brief Description of the Drawings

[0012]

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MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the heating control method according to the present invention, a plurality of heaters that generate radiant heat according to supplied energy are used to heat the object to be heated to a desired temperature distribution. Here, a heat forming method in which a glass plate is bent and formed into a desired shape by a forming unit equipped with a heating control device will be described as an example, but the object to be heated is not limited to a glass plate and may be other members or other shapes.

[0014] <Heating Control Device and Forming Device> FIG. 1 is a schematic configuration diagram of a thermoforming apparatus 300 including a heating control device 100. The thermoforming apparatus 300 includes a heating control device 100 and a forming unit 200. The heating control device 100 that heats a glass plate G as a body to be heated includes a plurality of heaters 11, a plurality of temperature sensors 13, a heater driving unit 17 that individually drives the plurality of heaters 11, and a control unit 19. The heating control device 100 performs heating control on the glass plate G placed on the forming unit 200 described later so as to have a temperature distribution suitable for its forming shape. Although not shown, the heating control device 100 may be provided with a mechanism that moves up and down in accordance with the operation of the forming unit 200 to avoid mutual collision.

[0015] (Configuration of Heating Control Device) FIG. 2 is a partially enlarged cross-sectional view schematically showing the state of heating of the glass plate G by the heater 11 and the state of temperature measurement of the glass plate G by the temperature sensor 13. The heater 11 generates radiant heat corresponding to the supplied energy input and heats the glass plate G as the body to be heated. The temperature sensor 13 is disposed on the side opposite to the heater 11 side of the heat shield plate 15 and measures the temperature of the heated glass plate G.

[0016] The plurality of heaters 11 are provided to face the glass plate G and mainly heat specific heating regions (exemplified as A1 and A2 in FIG. 2) of the different glass plates G by radiant heat. Each heating region may overlap with each other or may be an independent region. That is, each heater 11 may be disposed corresponding to a plurality of divided heating regions of the glass plate G, respectively, or may be disposed at an arbitrary position. In the present heating control device 100, it is particularly effective when the heating regions from the plurality of heaters 11 overlap and the relationship between the heater 11 and the heating measurement object and the heating control object is not a one-to-one relationship.

[0017] Further, each heater 11 is preferably arranged at an equal distance from the glass plate G and at equal intervals from each other within a range corresponding to the size of the glass plate G. As the heater 11, for example, various electric heaters such as tubular or block-shaped heaters such as a sheathed heater, a carbon heater, and a ceramic heater, or surface heaters such as a rubber heater and a foil heater can be used, and they generate heat according to the magnitude of the supplied energy (current, voltage). The heater 11 is not limited to the above-described electric heaters, and may be of other types as long as it can heat the object to be heated.

[0018] The temperature sensor 13 measures the temperature of the glass plate G from the gap between the arranged heaters 11. The temperature sensor 13 is preferably a non-contact type sensor that can measure the temperature of the glass plate G without contact. For example, an infrared sensor or the like can be used. The infrared sensor can stably measure a wide range of temperatures with high responsiveness. By making the temperature sensor 13 non-contact type, cable wiring and the like become unnecessary, and temperature measurement can be easily performed without complicating the mechanism. Further, since the temperature measurement position can be freely adjusted, the pitch of the measurement points and the like can be easily changed and adjusted according to the size of the glass plate G, the required measurement resolution, and the like for the purpose.

[0019] Note that an air-cooling device, a reflector, a heat shield plate, or the like may be placed between the temperature sensor 13 and the glass plate G.

[0020] The heater 11 is preferably arranged in a one - dimensional or two - dimensional matrix facing the heating region described above. FIG. 3 is a schematic diagram showing an arrangement example of the heater 11 and the temperature sensor 13. The heater 11 shown in FIG. 3 is a linear tube heater arranged in parallel with each other. A plurality of temperature sensors 13 are arranged in a grid along the longitudinal direction and the arrangement direction of the heater 11, and measure the temperature of the glass plate G from the gaps between the heaters 11 respectively. When using a linear heater 11, the glass plate G can be heated uniformly along the longitudinal direction of the heater 11, and the variation in temperature distribution can be suppressed. Also, when using a tube heater, among the plurality of temperature sensors 13 arranged along the tube heater, a configuration may be adopted in which any one of them is representative for temperature measurement. Further, a pair of heater groups each composed of a plurality of rows of tube heaters arranged in parallel with each other may be prepared, the height positions of the respective heater groups may be made different, and the longitudinal directions of the mutually parallel tube heaters may be crossed and arranged to generate a two - dimensional temperature distribution.

[0021] FIG. 4 is a schematic diagram showing another arrangement example of the heater 11 and the temperature sensor 13. As shown in FIG. 4, the heater 11 may be a surface heater arranged facing each heating region. In that case, by arranging the surface heaters in a two - dimensional matrix, a two - dimensional temperature distribution can be finely controlled. Thereby, the temperature and temperature distribution of each heating region arranged in one - dimension or two - dimension of the glass plate G can be measured. Note that the temperature sensor 13 only needs to be able to measure the temperature distribution of the glass plate G, and its method and type are not limited. For example, the temperatures of a plurality of locations on the glass plate G may be extracted at once from the image information by thermography.

[0022] The control unit 19 is configured as a computer including a processor such as a CPU, and storage devices such as a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), and an SSD (Solid State Drive). In this case, the functions of each part shown in FIG. 1 can be realized by the processor executing a predetermined program stored in the storage device.

[0023] (Configuration of the molding device) The forming unit 200 projects and presses a plurality of pins 21, which are movable members, against a glass plate G heated to a forming temperature by the heating control device 100 to form it into a desired shape. The plurality of pins 21 are supported with their axial directions aligned by a pin support portion 23. The glass plate G is placed on the upper end portions 21a of the pins 21, and the lower end portions 21b of the pins 21 are pushed up by a mold body 27 fixed to a lifting table 25. The upper surface 27a of the mold body 27 has the designed shape of the glass plate G to be formed, and by the plurality of pins 21 protruding according to the designed shape, the glass plate G is formed into a desired shape. Note that a heat insulating sheet may be placed between the upper end portions 21a of the pins 21 and the glass plate G.

[0024] FIG. 5 is a schematic explanatory diagram showing the forming operation of the glass plate G by the forming unit 200. The forming unit 200 drives the lifting table 25 to rise according to a command from the control unit 19 shown in FIG. 1. When the mold body 27 pushes up the pins 21, the designed shape of the upper surface 27a of the mold body 27 is reproduced by the upper end portions 21a of the pins 21. By pushing up the glass plate G by the upper end portions 21a of the pins 21, the glass plate G is formed into the designed shape. According to this configuration, forming into an arbitrary shape can be easily performed without the need for a mold.

[0025] The configuration of the forming unit 200 described above is an example, and other configurations may also be used. For example, the mold body 27 described above may be a mold formed by machining, cutting, printing, a structure using pins, or the like.

[0026] <Glass plate forming procedure> FIG. 6 is a process explanatory diagram showing a schematic temperature history of the glass forming process. The glass forming process includes a heating step (t 0 ~t 1 ), a forming step (t 1 ~t 2 ), a slow cooling step (t 2 ~t 3 ), and a cooling step (t 3 ~t 4) is included. Tf is the forming temperature, and Ts is the glass strain point. In particular, in the forming process, since the viscosity distribution of the glass plate due to heating affects the forming quality, it is necessary to approach the set temperature distribution as closely as possible. For example, for a part with a large bending curvature, the temperature is increased compared to a part with a small curvature to lower the viscosity and improve the formability. Also, for a part with a small bending curvature, the temperature is lowered compared to a part with a large curvature to increase the viscosity, making it difficult for the shape to sag while suppressing the occurrence of transfer marks on the glass plate.

[0027] When transitioning to the forming process, the temperature distribution of the glass plate, that is, the target temperature distribution of the glass plate in the heating process, can be set based on the result (ideal temperature distribution) of obtaining the optimal glass temperature distribution by forming simulation. The closer the actual temperature distribution of the glass plate is to the ideal temperature distribution, the more ideal glass forming with high precision and high productivity can be performed.

[0028] However, the temperature distribution reached by the glass plate in the heating process does not become ideal as expected due to various factors such as the physical properties of the glass plate, the forming shape, and the ambient temperature, as shown by the multiple dashed curves in the heating process of FIG. 6. Therefore, in this heating control device 100, the temperature distribution of the glass plate during heating is measured, and based on the measurement result, a simple thermal simulation is sequentially performed to optimally control the heater output. In this way, the variation in the reached glass temperature distribution due to the above factors and the like is canceled out by the optimal control of the heater output during heating.

[0029] FIG. 7 is a schematic functional block diagram of the heating control by the heating control device 100. This heating control includes the following configuration and procedure. The plurality of heaters 11 are arranged for each of the plurality of heating regions into which the glass plate G is divided, and each generates radiant heat. The target temperature distribution (ideal temperature distribution) of the glass plate G is input to the control unit 19. The supply energy calculation unit 19A obtains the supply energy (heater output) to be applied to each of the plurality of heaters 11, that is, the supply energy distribution (heater output distribution) set for each heater 11 to heat the glass plate G to the target temperature distribution. The heater driving unit 17 generates radiant heat corresponding to the supply energy distribution from the plurality of heaters 11 to heat the glass plate G. The temperature measurement unit 14 including the plurality of temperature sensors 13 shown in FIG. 1 measures the temperatures at a plurality of locations on the glass plate G and outputs information on the measured temperature distribution to the control unit 19. The difference calculation unit 19B calculates the difference between the input measured temperature distribution and the target temperature distribution for each heating region. The correction amount calculation unit 19C calculates the correction amount of the supply energy for each heater 11 based on the difference calculated by the difference calculation unit 19B. The corrected energy calculation unit 19D obtains the corrected energy distribution obtained by correcting the supply energy for each heater 11 by the correction amount, and outputs information on the corrected energy distribution to the heater driving unit 17. The heater driving unit 17 generates radiant heat corresponding to the corrected energy distribution from the plurality of heaters 11 to heat the glass plate G.

[0030] <First Heating Control> Next, the procedure of the first heating control, which is an example of the above-described heating control, will be specifically described. FIG. 8 is a flowchart showing the procedure of the first heating control by the heating control device 100. In the first heating control, first, the above-described ideal temperature distribution is obtained by three-dimensional forming simulation of the glass plate G (S11). In this forming simulation, the optimum temperature distribution when bending and forming the glass plate is obtained by thermal deformation analysis using a three-dimensional model.

[0031] Next, using the ideal temperature distribution obtained by the forming simulation as the target temperature distribution, the heater output of each of the plurality of heaters 11 is set, and each heater 11 is heated. At the same time, the temperature distribution of the heated glass plate G is measured by a plurality of temperature sensors 13 (S12).

[0032] Then, based on the information on the temperature distribution of the glass plate G measured after heating, the reaching temperature distribution of the glass plate G when continuing to heat with the set heater output distribution is predicted (S13). The prediction of the reaching temperature distribution here is performed by a simple analysis using, for example, a one-dimensional heat simulation model that can reduce the computational burden.

[0033] FIG. 9 is an explanatory diagram schematically showing a one-dimensional heat simulation model. In this heat simulation model, radiant heat from the plurality of heaters 11 is transmitted to the glass plate G supported on the upper parts of the pins of the plurality of pins 21 shown in FIG. 1, and the transmitted input heat is thermally conducted within the glass plate G and heat is removed to the pins 21 supporting the glass plate G. According to this model, since the measured temperature distribution of the glass plate G and the radiant heat from each heater 11 are known, the change in the temperature distribution due to heating of the glass plate G can be predicted. Although the model shown here has a simple model configuration, the heat simulation will be appropriately redesigned according to various conditions such as the configuration of the heating device and changes in the heating target.

[0034] Next, it is determined whether the predicted reaching temperature distribution is within the allowable error from a predetermined target temperature distribution (S14). If the predicted reaching temperature distribution is within the allowable error, the current heater output distribution is updated as it is (S15). On the other hand, if the predicted reaching temperature distribution exceeds the allowable error, the heater output distribution is obtained by inverse calculation from the difference between the reaching temperature distribution and the target temperature distribution and the form factor (S16).

[0035] In this inverse calculation, from the temperature distribution of the glass plate G after correction to be within the allowable error, the heater output distribution for obtaining such a temperature distribution is calculated. Here, the specific procedure of the inverse calculation will be described. The temperature of the glass plate can be expressed by Equation (1) when formulated in a one-dimensional integral type.

[0036]

Number

[0037] T glass : Temperature of the glass plate [K] t: Time [s] ρ: Density of the glass plate [kg / m 3 C p : Specific heat of the glass plate [J / kgK] k: Thermal conductivity of the glass plate [W / mK] V: Volume of the glass plate [m 3 S: Area of the glass plate [m 2 x: Coordinate of the glass plate [m] W heater : Heat flux per unit time of radiant heat from the heater (heat input) [W / m 2 W others : Heat flux per unit time of other heat (heat extraction) [W / m 2

[0038] The left side of Equation (1) is the change amount per unit time of the total heat quantity that the glass plate G has, the right side first term is the heat quantity that diffuses thermally per unit time in the glass plate G by heat conduction, and the right side second term is the total of the heat input quantity from the heater and the heat quantity per unit time to others. Since the process of obtaining the heater output distribution from Equation (1) involves an enormous amount of calculation, the equation is transformed as follows.

[0039] On the right side of Equation (1), the first term is called the diffusion term and exhibits the effect of smoothing (averaging) the temperature distribution by heat conduction. Therefore, it is the second term that actively forms the temperature distribution. When the heater output is changed, the temperature distribution changes due to the change in the second term, and then, due to the first term, a phenomenon occurs where the temperature distribution is smoothed. Also, regarding W out in the second term on the right side, it becomes a passive phenomenon where the radiative cooling amount due to diffuse reflection changes due to the change in the glass temperature caused by the change in the heater output. Focusing on the phenomenon before the temperature distribution is smoothed, the change in the glass temperature with respect to the change in the heat flux from the heater can be approximated by Equation (2) obtained by transforming Equation (1).

[0040]

Equation

[0041] When Equation (2) is rearranged, it becomes Equation (3), and the change in the glass temperature can be approximated by a relationship proportional to the change in the heat flux from the heater.

[0042]

Equation

[0043] At this time, dW in represents the direct radiation component from the heater, and the heat flux can be approximated as in Equation (4) using the form factor and the change amount of the heater output.

[0044]

Equation

[0045] By substituting Equation (4) into Equation (3) and introducing the calculation coefficient α, Equation (5) is derived.

[0046]

Equation

[0047] Equation (5) enables the calculation of the optimal solution by the least squares method, and from the difference dT between the current temperature distribution and the target temperature distribution, the heater output distribution dI to be changed can be obtained by inverse calculation.

[0048] VF: Shape factor from the heater to the glass plate dI: Correction amount of the heater output distribution α: Calculation coefficient Also, the subscript i represents the coordinates on the glass plate, and the subscript j represents the heater number (a total of n heaters).

[0049] That is, by the least squares method, the correction amount dI that minimizes the error of the system of linear equations prepared for each coordinate on the glass plate in Equation (5) is derived. In this way, since the change in the glass temperature with respect to the change in the heater output is modeled by a very simple approximate equation, real-time temperature control can be realized. Note that in order to derive the correction amount dI by the least squares method, it is preferable that the number of coordinates i (temperature evaluation points) on the glass plate is larger than the number of heaters j controlled, but if necessary, the temperature may be estimated by interpolation for non-measured coordinates.

[0050] The shape factor VF is a coefficient representing the geometric positional relationship between the heater 11 and the glass plate G in the heat transfer from the heater 11 to the glass plate G, and represents the ratio of the radiant energy radiated from one surface that reaches another surface in terms of the geometric shapes of the two surfaces. This shape factor is uniquely determined when the positional relationship between the configuration of the thermoforming apparatus 300 and the glass plate G is determined. Specifically, the shape factor is determined for each heating region and represents the geometric positional relationship between the heater 11 and the heating region. In this thermoforming apparatus 300, the above-described heater output distribution is calculated and set using the shape factor. Therefore, even if a change occurs in the positional relationship between the heater 11 and the glass plate G during the heating process, the shape factor can be recalculated according to the change, preventing the change from affecting the heater output. In particular, the plurality of heaters 11 in the heating control apparatus 100 of this configuration are arranged at a predetermined fixed distance in the normal direction of the glass plate G and are arranged parallel to the plate surface of the glass plate G, etc., and the positional relationship between the heater 11 and the glass plate G is simplified. Therefore, it becomes possible to calculate the shape factor using a simple theoretical formula, and even if a change occurs in the geometric positional relationship between the heater 11 and the glass plate G, it is not necessary to perform complex heat calculations, and it can be dealt with only by recalculating the shape factor. As a result, the correction amount of the heater output distribution can be accurately obtained in real time.

[0051] FIG. 10 and FIG. 11 are explanatory diagrams showing examples of the set outputs of the plurality of heaters 11 obtained by the above-described iterative calculation. The heater outputs of the plurality of heaters 11 (HT1 to HTn) are obtained from the correction amount of the heater output distribution obtained by the above-described iterative calculation and are individually set for each heater 11. FIG. 10 is an example of the set output arranged in one dimension shown in FIG. 3, and FIG. 11 is an example of the set output of the heaters 11 arranged in two dimensions (N rows and M columns) shown in FIG. 4. The set output shown as an example specifically becomes control parameters such as the current value and voltage value input to each heater 11. By setting the heater output independently for each heater 11, the temperature distribution of the glass plate G can be finely controlled.

[0052] FIG. 12 is an explanatory diagram showing an example of the heater output distribution of a plurality of heaters 11. The distribution of the heater output is not limited to a constant or smoothly continuous output distribution along the arrangement direction of the heaters 11. There are heating distributions in which regions with relatively large heater outputs are continuous, such as the heater numbers 1 to 5 and 34 to 37 shown in FIG. 12, heating distributions in which there are regions that heat discretely, such as the heater numbers 6 to 33, and heating distributions in which both of the above regions are mixed. The output distributions of the plurality of heaters 11 can be set with a high degree of freedom. Further, by using the constrained least squares method when solving the above-described equation (5), arbitrary restrictions such as upper and lower limits of the heater output can be provided for the derived heater output. Thus, by the optimization by the iterative calculation of the equation (5), a heating distribution can be obtained that can approximate the temperature of the glass plate G to the target temperature distribution with higher accuracy. Note that the number of points (i) for setting the temperature distribution of the glass plate G can be made larger than the number of heaters 11 (j) to enable calculation of the optimal solution.

[0053] FIG. 13 is a graph showing changes in the target temperature distribution of the glass plate G and the optimized calculated temperature distribution according to the number of iterative calculations. It can be seen that the optimized calculated temperature distribution in the first iterative calculation has a large gap from the target temperature distribution, but it approaches the target temperature distribution as the number of iterative calculations increases.

[0054] Referring again to FIG. 8, the heater output distribution for approaching the target temperature distribution obtained as described above is set as the heater output for heat simulation input (S17). Then, in S13, heat simulation is performed again using the set heater output, and the reached temperature distribution is predicted (S13). The processes of S16 and S17 described above are repeated until the reached temperature distribution becomes within the allowable error from the target temperature distribution (S14). When it becomes within the allowable error, the heater output distribution is updated as the heater output value for each heater 11 (S15). Then, the processes of S12 to S17 described above are repeated until the heating process ends (S18).

[0055] As described above, in the first heating control, when heating the glass plate G with the ideal temperature distribution as the target in the heating process, a thermal simulation is performed based on the measured temperature distribution measured by the plurality of temperature sensors 13, and the reaching temperature distribution under the conditions is predicted. The heater output distribution is obtained by inverse calculation so that the predicted reaching temperature distribution becomes the target temperature distribution. Then, the reaching temperature distribution when the glass plate G is heated with the obtained heater output distribution is predicted by thermal simulation, and if the predicted reaching temperature distribution is within the allowable error from the target temperature distribution, the heater output distribution is updated as the output value of each heater 11. By the feedforward control repeated in this heating process, the reaching temperature of the glass plate G at the end of the heating process can be made closer to the ideal temperature distribution. As a result, in the subsequent forming process, the glass plate G has a temperature distribution suitable for forming, and the glass plate G can be formed well.

[0056] Generally, in order to control the temperature distribution at a plurality of locations by the plurality of heaters 11 to a desired heating distribution or history, complicated control is required, and it is difficult to control with high precision and good responsiveness. However, according to this heating control, by individually adjusting the heater output of each of the plurality of heaters by thermal simulation during heating, it is possible to heat so as to draw an optimal temperature rise curve. Further, in this configuration, since the temperature of the glass plate G is directly measured from the gap between the heaters 11, the temperature distribution can be obtained with higher accuracy than indirect measurement such as converting the temperature value of the glass plate G from other measurement parameters or the temperature of other parts. Thereby, the thermal simulation and the feedforward control can be performed with high precision, and a more appropriate heater output distribution can be set.

[0057] And according to this heating control, the glass temperature can be controlled more quickly and stably, and the forming conditions can be determined quickly. Thereby, even when a large number of varieties are continuously produced, it becomes easy to instantaneously determine appropriate forming conditions, and the productivity of glass forming can be improved.

[0058] FIG. 14 is a graph showing an example in which the temperature distribution of the glass plate G is controlled to a V-shaped temperature distribution by the first heating control. FIG. 15 is a graph showing an example in which the temperature distribution of the glass plate G is controlled to an S-shaped temperature distribution by the first heating control. The target temperature distribution here is set in the range of 350° C. to 450° C., which is below the strain point of the glass plate G, in order to easily confirm the temperature controllability. The horizontal axis of each graph is the coordinate in the longitudinal direction of the glass plate G, and the vertical axis is the temperature. As shown in FIGS. 14 and 15, according to the first heating control, temperature distributions close to the V-shaped and S-shaped target temperature distributions are obtained.

[0059] FIG. 16 is a graph showing the relationship between the process time and the temperature of the glass plate G when the first heating control is started during heating for two types of glass plates G having different initial temperatures. The glass plate G of Example 1 having the initial temperature of room temperature T1 and the glass plate G of Example 2 having the initial temperature of T2 higher than room temperature were heated, and the first heating control was started from the time ta when they reached a substantially equilibrium state. As a result, in both Example 1 and Example 2, the target temperature Tt was reached in a short time immediately after the start of the first heating control, and an equilibrium state was achieved. Thus, by the feedforward control using the heat simulation model of the first heating control, highly robust heating control can be realized regardless of the initial temperature of the glass or the forming apparatus and the surrounding environment.

[0060] <Second Heating Control> FIG. 17 is a flowchart showing the procedure of the second heating control by the heating control device 100. In the second heating control, first, an ideal temperature distribution is obtained by three-dimensional forming simulation of the glass plate G (S21). In this forming simulation, the optimum temperature distribution when bending and forming the glass plate is obtained by thermal deformation analysis using a three-dimensional model.

[0061] Next, the heater output of each of the plurality of heaters 11 is set with the ideal temperature distribution obtained by the forming simulation as the target temperature distribution, and each heater 11 is heated. At the same time, the temperature distribution of the heated glass plate G is measured by the temperature sensor 13 (S22). The steps of S21 and S22 above are the same as the steps of S11 and S12 of the first heating control.

[0062] Then, the difference between the measured temperature distribution and the ideal temperature distribution of the measured glass plate G is obtained, and the heater output distribution is inversely calculated from the obtained difference and the shape factor (S23). The procedure for the inverse calculation is the same as S16 (Fig. 8) in the first heating control described above. That is, the heater output distribution for making the measured temperature distribution into the ideal temperature distribution is calculated.

[0063] Next, based on the information of the obtained heater output distribution, the heater output is set by PID control (S24). Then, the heater output is updated as the heater output value for each heater 11 (S25). The processes of S22 to S25 described above are repeated until the heating process ends (S26).

[0064] Fig. 18 is a conceptual diagram of PID control and feedback control in the second heating control. The heater output is PID-controlled according to the difference between the ideal temperature distribution and the measured temperature distribution measured by the temperature sensor. The temperature distribution of the glass plate G after the PID control is measured, and the information of the obtained temperature distribution is fed back to the calculation of the next heater output distribution. By such feedback control, it is possible to quickly converge to the target temperature.

[0065] In this heating control, the ideal temperature distribution is set as the target temperature distribution, but an intermediate target temperature distribution may be provided during the heating process, and the ideal temperature distribution may be gradually approached step by step. In that case, the glass plate G can be heated to the ideal temperature distribution with an intentional heating distribution and history according to the shape, characteristics, etc. of the glass plate G, and the design freedom can be improved.

[0066] FIG. 19 is a graph showing an example in which the temperature distribution of the glass plate G is controlled to a V-shaped temperature distribution by the second heating control. FIG. 20 is a graph showing an example in which the temperature distribution of the glass plate G is controlled to an S-shaped temperature distribution by the second heating control. The target temperature distributions are each set in the range of 350°C to 450°C. The horizontal axis of each graph is the coordinate in the longitudinal direction of the glass plate G, and the vertical axis is the temperature. As shown in FIGS. 19 and 20, according to the second heating control, a temperature distribution closer to the V-shaped and S-shaped target temperature distributions can be obtained more accurately than in the case of the first heating control.

[0067] <Improvement effect in the forming process> According to the first heating control and the second heating control described above, the time until the heating conditions are set can be shortened, and an effect of suppressing the shape variation of the molded product can be obtained. Conventionally, the heating conditions were set based on calculations and tests in the pre-preparation before molding, and then a molding test was performed to verify the set heating conditions. On the other hand, in this heating control, an ideal temperature distribution is obtained by optimization calculation, a molding test is performed based on this ideal temperature distribution, and while obtaining the deviation from the ideal temperature distribution during the molding test, the heater output distribution is updated by inverse calculation. Therefore, unnecessary man-hours can be reduced and the heating conditions can be set efficiently. In addition, since an ideal temperature distribution can be achieved, the variation of the molded product can be suppressed and high-quality molding is possible.

[0068] The present invention is not limited to the above-described embodiments, and it is also contemplated by the present invention that those skilled in the art can make changes and applications based on combining each configuration of the embodiments, the description of the specification, and well-known techniques, and are included in the scope for which protection is sought.

[0069] As described above, the following matters are disclosed in this specification. (1) A heating control method for heating a body to be heated by a plurality of heaters that generate radiant heat and controlling the temperature of the body to be heated to a desired target temperature distribution, wherein the plurality of heaters are arranged for each of a plurality of heating regions obtained by dividing the body to be heated, Supply energy to be applied to each of the plurality of heaters, and obtain a supply energy distribution set for each heater to heat the object to be heated to the target temperature distribution. Generate radiant heat corresponding to the supply energy distribution from the plurality of heaters to heat the object to be heated. Measure the temperatures at a plurality of locations on the heated object to obtain a measured temperature distribution. Calculate the difference between the measured temperature distribution and the target temperature distribution for each heating region. Based on the difference, calculate a correction amount for the supply energy for each heater. Obtain a corrected energy distribution in which the supply energy for each heater is corrected by the correction amount. Generate radiant heat corresponding to the corrected energy distribution from the plurality of heaters to heat the object to be heated. Heating control method. According to this heating control method, by generating radiant heat corresponding to the corrected energy distribution corrected based on the difference between the measured temperature distribution and the target temperature distribution of the object to be heated from a plurality of heaters, the temperature distribution of the object to be heated can be efficiently controlled to the target temperature distribution regardless of the initial temperature of the object to be heated, the molding apparatus, etc. and the surrounding environment.

[0070] (2) The heating control method according to (1), wherein the correction amount is calculated according to the difference obtained for each heating region and a form factor representing the geometric positional relationship between the heater and the heating region. According to this heating control method, since the correction amount is obtained using the form factor according to the geometric positional relationship between the heater and the heating region to be heated, the correction energy can be set more accurately and the temperature distribution of the object to be heated can be accurately controlled.

[0071] (3) Obtain a system of linear equations including the difference and the form factor for each coordinate on the object to be heated. Obtain, by the least squares method, a correction amount that minimizes the error of the system of linear equations. The heating control method according to (2), wherein based on the obtained correction amount, the correction energy for each of the plurality of heaters is calculated. According to this heating control method, a correction amount that minimizes the error of the system of linear equations can be easily obtained by the least squares method, making it easier to perform temperature control in real time.

[0072] (4) The heating control method according to (3), wherein the correction amount is obtained by performing a plurality of iterative calculations so that the root mean square error is minimized. According to this heating control method, the correction amount can be set with higher accuracy by performing a plurality of iterative calculations.

[0073] (5) Predict the temperature distribution reached by the object to be heated when heating the object to be heated by the plurality of heaters based on the correction energy distribution by thermal simulation. The heating control method according to any one of (1) to (4), wherein the calculation of the correction amount is repeated until the predicted temperature distribution reached is within the allowable error. According to this heating control method, the correction amount can be calculated with high accuracy by repeatedly performing feedforward control so that the predicted temperature distribution reached predicted by thermal simulation approaches the target temperature distribution.

[0074] (6) The heating control method according to (1), wherein the plurality of heaters are PID-controlled based on the correction amount, and information on the measured temperature distribution obtained by measuring the temperature distribution of the object to be heated after the PID control is fed back to the calculation of the next correction amount. According to this heating control method, the temperature distribution of the object to be heated can be quickly converged to the target temperature by PID control and feedback control.

[0075] (7) After setting the target temperature distribution to an intermediate temperature distribution during the process of reaching the predetermined final temperature distribution of the object to be heated and heating the object to be heated to the intermediate temperature distribution at least once, Set the target temperature distribution to the final temperature distribution and heat the object to be heated. (6) The heating control method according to (6). According to this heating control method, by setting the target temperature distribution of the object to be heated in multiple stages, it is possible to heat the object to be heated with an intentional heating distribution and history according to the shape, characteristics, etc. of the object to be heated.

[0076] (8) The heating control method according to any one of (1) to (7), wherein the object to be heated is glass. According to this heating control method, the viscosity distribution of glass can be easily changed.

[0077] (9) Pressing a movable member against the object to be heated heated by the heating control method according to any one of (1) to (7) to form a molded body having a desired shape. Hot forming method. According to this hot forming method, the object to be heated can be made to have a desired temperature distribution with high precision.

[0078] (10) The hot forming method according to (9), wherein the object to be heated is glass. According to this hot forming method, glass can be made to have a viscosity distribution suitable for forming, and the formability can be improved.

[0079] (11) A heating control device that heats an object to be heated by radiant heat and controls the temperature of the object to be heated to a desired target temperature distribution, A plurality of heaters arranged for each of a plurality of heating regions obtained by dividing the object to be heated, the heaters generating radiant heat; Supply energy applied to each of the plurality of heaters, and a supply energy calculation unit that obtains a supply energy distribution set for each heater to heat the object to be heated to the target temperature distribution; A heater driving unit that generates radiant heat corresponding to the supply energy distribution from the plurality of heaters to heat the object to be heated; A temperature measurement unit that measures the temperatures at a plurality of locations of the object to be heated and outputs information on the measured temperature distribution; A difference calculation unit that calculates the difference between the measured temperature distribution and the target temperature distribution for each heating region; A correction amount calculation unit that calculates a correction amount of the supply energy for each heater based on the difference; A correction energy calculation unit that obtains a corrected energy distribution obtained by correcting the supply energy with the correction amount for each heater; comprising; The heater driving unit generates radiant heat corresponding to the corrected energy distribution from the plurality of heaters to heat the object to be heated. Heating control device. According to this heating control device, by generating radiant heat corresponding to the corrected energy distribution corrected based on the difference between the measured temperature distribution and the target temperature distribution of the object to be heated from a plurality of heaters, the temperature distribution of the object to be heated can be efficiently controlled to the target temperature distribution regardless of the initial temperature of the object to be heated, the molding device, etc. and the surrounding environment.

[0080] (12) The heating control device according to (11), wherein the temperature measurement unit is a non-contact temperature sensor. According to this heating control device, the temperature of the object to be heated can be easily measured without providing a complicated mechanism. In addition, the measurement position of the object to be heated can be easily changed and adjusted.

[0081] (13) The heating control device according to (12), wherein the temperature sensor is an infrared sensor. According to this heating control device, a wide range of temperatures can be stably measured with high response speed.

[0082] (14) The heating control device according to (12) or (13), wherein the temperature sensor is arranged in a one-dimensional or two-dimensional matrix facing the plurality of heating regions. According to this heating control device, the temperature distribution along the one-dimensional or two-dimensional matrix can be measured.

[0083] (15) The heating control device according to any one of (11) to (14), wherein the heater is a linear tube heater. According to this heating control device, the object to be heated can be uniformly heated along the longitudinal direction of the linear tube heater, and the variation in the temperature distribution can be suppressed.

[0084] (16) The heater is a surface heater arranged corresponding to each of the heating regions, and the heating control device according to any one of (11) to (14). According to this heating control device, the temperature distribution can be controlled for each heating region.

[0085] (17) The heating control device according to any one of (11) to (16), which heats the object to be heated to the molding temperature, a molding part that presses a movable member against the object to be heated heated by the heating control device to mold the object to be heated, and a heat molding device including the same. According to this heat molding device, by molding the object to be heated heated to a desired temperature distribution with the molding part, the object to be heated can be molded in a state suitable for molding.

Explanation of Signs

[0086] 11 Heater 13 Temperature sensor 14 Temperature measurement part 15a Measurement window 17 Heater drive part 19 Control part 19A Supply energy calculation part 19B Difference calculation part 19C Correction amount calculation part 19D Correction energy calculation part 21 Pin 21a Upper end part 21b Lower end part 23 Pin support part 25 Lifting table 27 Mold body 27a Upper surface 29 Actuator 29a Movable part 100 Heating control device 200 Molding part 300 Heat molding device G Glass plate (object to be heated)

Claims

1. A heating control method for heating a body to be heated by a plurality of heaters that generate radiant heat and controlling the temperature of the body to be heated to a desired target temperature distribution, comprising: The plurality of heaters are arranged for each of a plurality of heating regions obtained by dividing the body to be heated; Obtaining a supply energy distribution set for each heater for heating the body to be heated to the target temperature distribution, which is the supply energy applied to each of the plurality of heaters; Generating radiant heat corresponding to the supply energy distribution from the plurality of heaters to heat the body to be heated; Measuring the temperatures at a plurality of locations on the heated body to be heated to obtain a measured temperature distribution; Calculating the difference between the measured temperature distribution and the target temperature distribution for each heating region; Calculating a correction amount of the supply energy for each heater based on the difference; Obtaining a corrected energy distribution in which the supply energy for each heater is corrected by the correction amount; Generating radiant heat corresponding to the corrected energy distribution from the plurality of heaters to heat the body to be heated; A heating control method.

2. Calculating the correction amount according to the difference obtained for each heating region and a form factor representing the geometric positional relationship between the heater and the heating region; The heating control method according to claim 1.

3. Obtaining a system of linear equations including the difference and the form factor for each coordinate on the body to be heated; Obtaining, by the least squares method, a correction amount that minimizes the error of the system of linear equations; Calculating the corrected energy for each of the plurality of heaters based on the obtained correction amount; The heating control method according to claim 2.

4. Obtaining the correction amount by performing multiple iterative calculations so that the root mean square error is minimized; The heating control method according to claim 3.

5. Predicting the temperature distribution reached by the body to be heated when the body to be heated is heated by the plurality of heaters based on the corrected energy distribution by thermal simulation; Repeating the calculation of the correction amount until the predicted temperature distribution reached is within the allowable error; The heating control method according to claim 1.

6. Performing PID control on the plurality of heaters based on the correction amount, and feeding back information on the measured temperature distribution obtained by measuring the temperature distribution of the body to be heated after the PID control to the calculation of the next correction amount; The heating control method according to claim 1.

7. The target temperature distribution is set to an intermediate temperature distribution during the process of reaching a preset final temperature distribution of the object to be heated, and after heating the object to be heated to the intermediate temperature distribution at least once, the target temperature distribution is set to the final temperature distribution to heat the object to be heated, The heating control method according to claim 6.

8. The object to be heated is glass, The heating control method according to any one of claims 1 to 7.

9. A movable member is pressed against the object to be heated heated by the heating control method according to any one of claims 1 to 7 to form a molded body having a desired shape, Heat forming method.

10. The object to be heated is glass, The heat forming method according to claim 9.

11. A heating control device that heats an object to be heated by radiant heat and controls the temperature of the object to be heated to a desired target temperature distribution, comprising: a plurality of heaters arranged for each of a plurality of heating regions obtained by dividing the object to be heated, which generate radiant heat; a supply energy calculation unit that calculates a supply energy distribution that is supply energy applied to each of the plurality of heaters and is set for each heater to heat the object to be heated to the target temperature distribution; a heater driving unit that generates radiant heat corresponding to the supply energy distribution from the plurality of heaters to heat the object to be heated; a temperature measurement unit that measures the temperatures at a plurality of locations of the object to be heated and outputs information on the measured temperature distribution; a difference calculation unit that calculates a difference between the measured temperature distribution and the target temperature distribution for each heating region; a correction amount calculation unit that calculates a correction amount of the supply energy for each heater based on the difference; a correction energy calculation unit that obtains a corrected energy distribution in which the supply energy for each heater is corrected by the correction amount; and comprising the heater driving unit generates radiant heat corresponding to the corrected energy distribution from the plurality of heaters to heat the object to be heated. Heating control device.

12. The temperature measurement unit is a non-contact temperature sensor, The heating control device according to claim 11.

13. The temperature sensor is an infrared sensor, The heating control device according to claim 12.

14. The temperature sensors are arranged in a one-dimensional or two-dimensional matrix facing the plurality of heating regions, The heating control device according to claim 12.

15. The heater is a linear tube heater, The heating control device according to claim 11.

16. The heater is a surface heater arranged corresponding to each of the heating regions. The heating control device according to claim 11.

17. The heating control device according to any one of claims 11 to 16, which heats the object to be heated to a molding temperature, a molding unit that presses a movable member against the object to be heated heated by the heating control device to mold the object to be heated, A thermoforming apparatus comprising:

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