JP2022059444A - Heating device and thermoforming device - Google Patents

Abstract

To provide a heating device that can reduce a difference between a temperature fluctuation on an upper surface and a temperature fluctuation on a lower surface during a heating period, and a thermoforming device equipped with the heating device.SOLUTION: There is provided a heating device 30, comprising: an upper temperature sensor 13; a lower temperature sensor 23; an upper heater 10; a lower heater 20; and a heater control unit 52, in which temperatures of the upper heater and lower heater are controlled based on a measured temperature by the upper temperature sensor and lower temperature sensor. The heater control unit 52 controls temperatures of the upper heater 10 and the lower heater 20 so as to match the measured temperature of one of measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23 to the measured temperature of the other temperature from a start of heating a sheet 90 by the upper heater 10 and the lower heater 20 until the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23 reach a target temperature Tt.SELECTED DRAWING: Figure 5

Description

The present invention relates to a heating device and a thermoforming device including a heating device.

Patent Document 1 discloses a heating device for heating a sheet. Further, a thermoforming device including a heating device and a molding device for molding a sheet heated by the heating device is disclosed. The heating device includes a heater that heats the surface of the sheet, a temperature measuring unit that measures the surface temperature of the sheet, and a heater control unit that controls the temperature of the heater. The heater control unit has a first temperature control means that controls the temperature of the heater to be sequentially lowered from the initial temperature according to the measured surface temperature, and a surface temperature that is controlled by the first temperature control means as the target temperature. It has a second temperature control means, which starts feedback control for controlling the temperature of the heater so that the surface temperature approaches the target temperature according to the comparison result between the surface temperature and the target temperature. The first temperature control means repeats the control of lowering the temperature of the heater when the surface temperature reaches a temperature information indicating a predetermined temperature lower than the target temperature, changing the temperature information to a higher temperature.

Japanese Patent No. 6472213

By the way, the upper heater that heats the upper surface of the sheet (the upper heater arranged above the upper surface of the sheet) and the lower heater that heats the lower surface of the sheet (the lower heater arranged below the lower surface of the sheet). ), It was difficult to heat the upper surface side and the lower surface side of the sheet equally when heating the sheet. More specifically, the temperature fluctuation (temperature) of the upper surface of the sheet during the period from the start of heating of the sheet by the upper heater and the lower heater to the temperature of the upper surface and the lower surface of the sheet reaching the target temperature. The transition of change) and the temperature fluctuation of the lower surface (transition of temperature change) may be significantly different.

In this way, the difference between the temperature fluctuation on the upper surface and the temperature fluctuation on the lower surface of the sheet becomes large, so that between the upper portion (upper half) and the lower portion (lower half) of the sheet at the end of heating, In some cases, the difference in temperature distribution in the thickness direction became large. That is, the temperature distribution from the upper surface of the sheet to the center in the thickness direction and the temperature distribution from the lower surface of the sheet to the center in the thickness direction may be significantly different. Furthermore, when a plurality of sheets are heated in sequence by a heating device, the temperature fluctuation (change in temperature change) on the upper surface of the sheet and the temperature fluctuation (change in temperature change) on the lower surface may differ greatly among the plurality of sheets. In some cases, the temperature distribution in the thickness direction of the sheets was significantly different between the sheets at the end of heating.

Therefore, for example, when the thermoplastic sheet is heated by a heating device, the degree of softening or melting between the upper portion (upper half) and the lower portion (lower half) of the sheet at the end of heating is as follows. Sometimes the difference was big. Furthermore, the degree of softening or melting in the thickness direction of the sheets may be significantly different among the plurality of sheets that have been sequentially heated. For this reason, when the sheet is subsequently molded by the molding apparatus, the difference in the degree of deformation (elongation) of the sheet between the sheets becomes large, and the quality of the molded product may not be stable.

When a carbon fiber sheet impregnated with a liquid thermosetting resin is heated to cure the thermosetting resin to form a carbon fiber composite sheet, the upper portion (upper half) and lower portion of the sheet are formed. There was a large difference in the degree of curing of the resin with (lower half). Furthermore, the degree of curing of the resin in the thickness direction of the sheets may be significantly different between the plurality of sheets that have been sequentially heated. Therefore, the quality of the carbon fiber composite sheet may not be stable.

The present invention has been made in view of the present situation, and includes a heating device capable of reducing the difference between the temperature fluctuation of the upper surface and the temperature fluctuation of the lower surface of the sheet during the heating period, and the heating device. It is an object of the present invention to provide a thermoforming apparatus.

In one aspect of the present invention, in a heating device for heating a sheet, an upper heater for heating the upper surface of the sheet, a lower heater for heating the lower surface of the sheet, and an upper temperature for measuring the temperature of the upper surface of the sheet. A heater that controls the temperatures of the upper heater and the lower heater based on the sensors, the lower temperature sensor that measures the temperature of the lower surface of the sheet, and the measured temperatures of the upper temperature sensor and the lower temperature sensor. The heater control unit includes a control unit, and the heater control unit starts heating the sheet by the upper heater and the lower heater, and then the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. In a heating device that controls the temperatures of the upper heater and the lower heater so that the measured temperature of one of the measured temperatures of the upper temperature sensor and the lower temperature sensor is adjusted to the measured temperature of the other. be.

The above-mentioned heating device includes an upper heater that heats the upper surface of the sheet and a lower heater that heats the lower surface of the sheet. The upper heater and the lower heater are provided so that when the sheet is heated, the upper heater is located above the upper surface of the sheet and the lower heater is located below the lower surface of the sheet. Further, this heating device includes an upper temperature sensor that measures the temperature of the upper surface of the sheet and a lower temperature sensor that measures the temperature of the lower surface of the sheet.

Further, the above-mentioned heating device includes a heater control unit that controls the temperatures of the upper heater and the lower heater based on the measured temperatures of the upper temperature sensor and the lower temperature sensor. This heater control unit starts heating the seat by the upper heater and the lower heater until the measured temperature of the upper temperature sensor and the lower temperature sensor reaches the target temperature, the upper temperature sensor and the lower temperature. The temperatures of the upper heater and the lower heater are controlled so that the measured temperature of one of the measured temperatures of the sensor is matched with the measured temperature of the other.

By doing so, the temperature fluctuation of the upper surface (transition of temperature change) and the temperature fluctuation of the lower surface of the sheet during the period from the start of heating of the sheet to the time when the upper surface temperature and the lower surface temperature of the sheet reach the target temperature. The difference from (transition of temperature change) can be reduced. In other words, during the heating period until the upper and lower surface temperatures of the sheet reach the target temperature, the temperature fluctuations on the upper surface (change in temperature) and the temperature fluctuations on the lower surface (change in temperature) of the sheet are substantially the same. Can be.

As a result, the difference in temperature distribution in the thickness direction between the upper half and the lower half of the sheet at the end of heating becomes small. That is, the difference between the temperature distribution from the upper surface of the sheet to the center in the thickness direction and the temperature distribution from the lower surface of the sheet to the center in the thickness direction can be reduced. Furthermore, when a plurality of sheets are heated in sequence by a heating device, the difference between the temperature fluctuations on the upper surface (change in temperature) and the temperature fluctuation on the lower surface (change in temperature) of the upper surface of the sheets becomes smaller among the plurality of sheets. , The difference in temperature distribution in the thickness direction of the sheets is also small among the plurality of sheets.

Therefore, for example, when the thermoplastic sheet is heated by the above-mentioned heating device, the degree of softening or melting differs between the upper portion (upper half) and the lower portion (lower half) of the sheet. It can be made smaller. Furthermore, the difference in the degree of softening or melting in the thickness direction of the sheets can be reduced even among the plurality of sheets that have been sequentially heated. Therefore, when the sheet is subsequently molded by the molding apparatus, the difference in the degree of deformation (elongation) of the sheet between the sheets becomes small, and the quality of the molded product becomes stable.

Further, when the carbon fiber sheet impregnated with the liquid thermosetting resin is heated by the above-mentioned heating device to cure the thermosetting resin to form the carbon fiber composite sheet, the upper portion of the sheet ( The difference in the degree of curing of the resin can be reduced between the upper half) and the lower portion (lower half). Furthermore, it is possible to reduce the difference in the degree of curing of the resin in the thickness direction of the sheets even among the plurality of sheets that have been sequentially heated. Therefore, the quality of the formed carbon fiber composite sheet is stable.

Further, in the heating device, the upper heater and the lower heater have a distance D1 between the upper heater and the upper surface of the sheet when the heating of the sheet is started, and the lower heater. It is preferable to use a heating device provided so that the distance D2 between the side heater and the lower surface of the sheet satisfies the relationship D1 <D2.

An upper heater that heats the upper surface of the sheet (upper heater arranged above the upper surface of the sheet) and a lower heater that heats the lower surface of the sheet (lower heater arranged below the lower surface of the sheet). When a sheet (for example, a sheet made of a thermoplastic resin or a sheet containing a thermoplastic resin) is heated, the sheet may be softened or melted by the heating, and the sheet may be deformed so as to hang down. In this case, as the softening or melting of the sheet progresses with the lapse of the heating time, the upper surface of the sheet moves away from the upper heater, and conversely, the lower surface of the sheet approaches the lower heater.

With this in mind, in the heating device described above, the upper heater and the lower heater are located on the upper side when the sheet is placed in a position where it is heated by the heating device (that is, when the heating of the sheet is started). The distance D1 between the heater and the upper surface of the seat and the distance D2 between the lower heater and the lower surface of the seat are provided so as to satisfy the relationship D1 <D2. By doing so, even when the sheet is deformed so as to hang down due to heating, it is possible to prevent the sheet from coming into contact with the lower heater, and the upper heater and the lower heater make the sheet. Can be heated appropriately.

Further, in any of the heating devices, the heater control unit starts heating the sheet by the upper heater and the lower heater, and then the measured temperatures of the upper temperature sensor and the lower temperature sensor. The measurement temperature of one of the measurement temperatures of the upper temperature sensor and the lower temperature sensor, which is set as the reference measurement temperature, is followed by the measurement temperature of the other until the temperature reaches the target temperature. It is preferable to use a heating device that controls the temperature of the upper heater and the lower heater.

In the above-mentioned heating device, the upper side during the period from when the heater control unit starts heating the sheet by the upper heater and the lower heater until the measured temperature of the upper temperature sensor and the lower temperature sensor reaches the target temperature. The temperatures of the upper heater and the lower heater are controlled so that the measured temperature of one of the measured temperatures of the temperature sensor and the lower temperature sensor, which is set as the reference measured temperature, is followed by the measured temperature of the other. In other words, the heater control unit uses the upper heater so that the measured temperature of one of the upper temperature sensor and the lower temperature sensor, which is set as the reference temperature sensor, is followed by the measured temperature of the other temperature sensor. And control the temperature of the lower heater.

Specifically, the heater control unit controls the temperatures of the upper heater and the lower heater so that the measurement temperature of the lower temperature sensor, which is set as the reference measurement temperature, follows the measurement temperature of the upper temperature sensor, for example. do. Alternatively, on the contrary, the temperatures of the upper heater and the lower heater are controlled so that the measurement temperature of the upper temperature sensor set as the reference measurement temperature is followed by the measurement temperature of the lower temperature sensor.

By doing so, the temperature fluctuation of the upper surface (transition of temperature change) and the temperature fluctuation of the lower surface of the sheet during the period from the start of heating of the sheet to the time when the upper surface temperature and the lower surface temperature of the sheet reach the target temperature. The difference from (transition of temperature change) can be reduced. In other words, the temperature fluctuation (transition of temperature change) between the upper surface and the lower surface of the sheet can be substantially the same during the heating period until the upper surface temperature and the lower surface temperature of the sheet reach the target temperature.

As a result, the difference in temperature distribution in the thickness direction between the upper portion (upper half) and the lower portion (lower half) of the sheet at the end of heating becomes small. That is, the difference between the temperature distribution from the upper surface of the sheet to the center in the thickness direction and the temperature distribution from the lower surface of the sheet to the center in the thickness direction can be reduced. Furthermore, when a plurality of sheets are heated in sequence by a heating device, the difference between the temperature fluctuations on the upper surface (change in temperature) and the temperature fluctuation on the lower surface (change in temperature) of the upper surface of the sheets becomes smaller among the plurality of sheets. , The difference in temperature distribution in the thickness direction of the sheets is also small among the plurality of sheets.

Further, in any of the heating devices, the heater control unit starts heating the sheet by the upper heater and the lower heater, and then the measured temperature of the upper temperature sensor and the lower temperature sensor. Compares the measured temperature of the upper temperature sensor with the measured temperature of the lower temperature sensor until the temperature reaches the target temperature, and adjusts the measured temperature of the higher temperature or the lower temperature to the measured temperature of the other. As described above, it is preferable to use a heating device that controls the temperatures of the upper heater and the lower heater.

In the above-mentioned heating device, the upper side during the period from when the heater control unit starts heating the sheet by the upper heater and the lower heater until the measured temperature of the upper temperature sensor and the lower temperature sensor reaches the target temperature. By comparing the measured temperature of the temperature sensor with the measured temperature of the lower temperature sensor, the temperatures of the upper heater and the lower heater are controlled so that the measured temperature of the higher temperature or the lower temperature matches the measured temperature of the other. .. Specifically, the heater control unit compares, for example, the measured temperature of the upper temperature sensor and the measured temperature of the lower temperature sensor at regular time intervals, and measures the measured temperature of the higher temperature sensor and the measured temperature of the lower temperature sensor. The temperature of the upper heater and the lower heater is controlled so as to match the temperature. Alternatively, on the contrary, the temperatures of the upper heater and the lower heater are controlled so as to match the measured temperature of the lower temperature side with the measured temperature of the higher temperature side.

By doing so, the temperature fluctuation of the upper surface (transition of temperature change) and the temperature fluctuation of the lower surface of the sheet during the period from the start of heating of the sheet to the time when the upper surface temperature and the lower surface temperature of the sheet reach the target temperature. The difference from (transition of temperature change) can be reduced. In other words, the temperature fluctuation (transition of temperature change) between the upper surface and the lower surface of the sheet can be substantially the same during the heating period until the upper surface temperature and the lower surface temperature of the sheet reach the target temperature.

As a result, the difference in temperature distribution in the thickness direction between the upper portion (upper half) and the lower portion (lower half) of the sheet at the end of heating becomes small. That is, the difference between the temperature distribution from the upper surface of the sheet to the center in the thickness direction and the temperature distribution from the lower surface of the sheet to the center in the thickness direction can be reduced. Furthermore, when a plurality of sheets are heated in sequence by a heating device, the difference between the temperature fluctuations on the upper surface (change in temperature) and the temperature fluctuation on the lower surface (change in temperature) of the upper surface of the sheets becomes smaller among the plurality of sheets. , The difference in temperature distribution in the thickness direction of the sheets is also small among the plurality of sheets.

The measured temperature of the higher temperature (low temperature) during the period from the start of heating the seat by the upper heater and the lower heater until the measured temperature of the upper temperature sensor and the lower temperature sensor reaches the target temperature. May be the measured temperature of the upper temperature sensor, or may be the measured temperature of the lower temperature sensor. That is, during the heating period until the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature, the relationship between the measured temperature of the upper temperature sensor and the measured temperature of the lower temperature sensor is constant (always one side). Is high temperature and the other is low temperature), but the high and low alternate.

Further, in any of the heating devices, the heater control unit is the upper temperature sensor and the lower temperature sensor after the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. It is preferable to use a heating device that controls the temperatures of the upper heater and the lower heater so that the measured temperature of the above is maintained at the target temperature.

In the above-mentioned heating device, the heater control unit maintains the measured temperatures of the upper temperature sensor and the lower temperature sensor at the target temperature after the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. , Control the temperature of the upper heater and the lower heater. By doing so, the difference in temperature distribution in the thickness direction between the upper half and the lower half of the sheet can be further reduced. That is, the difference between the temperature distribution from the upper surface of the sheet to the center in the thickness direction and the temperature distribution from the lower surface of the sheet to the center in the thickness direction can be further reduced. Furthermore, when a plurality of sheets are heated in order by a heating device, the difference in the temperature fluctuation (change in temperature change) on the upper surface and the temperature fluctuation (change in temperature) on the lower surface of the sheets is further increased among the plurality of sheets. It becomes smaller, and the difference in temperature distribution in the thickness direction of the sheets becomes even smaller among the plurality of sheets.

Another aspect of the present invention is a thermoforming apparatus comprising one of the above heating devices and a molding apparatus for molding the sheet heated by the heating apparatus.

The thermoforming apparatus described above includes the heating apparatus described above. Therefore, the difference in temperature distribution in the thickness direction between the upper half and the lower half of the sheet at the end of heating by the heating device becomes small. That is, the difference between the temperature distribution from the upper surface of the sheet to the center in the thickness direction and the temperature distribution from the lower surface of the sheet to the center in the thickness direction can be reduced. Furthermore, when a plurality of sheets are heated in sequence by a heating device, the difference between the temperature fluctuations on the upper surface (change in temperature) and the temperature fluctuation on the lower surface (change in temperature) of the upper surface of the sheets becomes smaller among the plurality of sheets. , The difference in temperature distribution in the thickness direction of the sheets is also small among the plurality of sheets.

Further, the above-mentioned thermoforming apparatus includes a forming apparatus for forming a sheet heated by the above-mentioned heating apparatus. By sequentially molding a plurality of sheets that have been sequentially heated by the above-mentioned heating device by a molding device, a molded product (molded sheet) having stable quality can be obtained.

It is a schematic block diagram of the thermoforming apparatus which concerns on Embodiments 1 and 2. It is a top view of a heater. It is a top view of the heater element which constitutes a heater. It is a figure explaining the heating of a sheet by a heater. It is a figure explaining the heater temperature control which concerns on Embodiment 1. FIG. It is a figure explaining the heater temperature control which concerns on Embodiment 2.

<Embodiment 1>
Next, Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a heating device 30 and a thermoforming device 1 according to the first embodiment. The thermoforming apparatus 1 includes a heating apparatus 30 and a forming apparatus 40. Further, the thermoforming device 1 includes a sheet supply device 81, a sheet holding device 83, a transfer control unit 51, and a molding device control unit 53. The transfer control unit 51 and the molding device control unit 53 have a circuit unit including a CPU and the like (not shown).

The seat supply device 81 and the seat holding device 83 are operated under the control of the transport control unit 51. Specifically, the sheet supply device 81 takes out one sheet 90 from a plurality of sheets 90 (unmolded sheets 91) mounted on the sheet mounting table 85 under the control of the transport control unit 51, and takes out one sheet 90. It is supplied to the holding device 83. Further, the seat holding device 83 holds the sheet 90 supplied by the sheet supply device 81 and conveys it to the heating device 30 under the control of the transfer control unit 51.

The sheet 90 is a thermoplastic sheet, specifically, a sheet made of a thermoplastic resin. In the first embodiment, a case where a cut-shaped (single-leaf type) sheet is used as the sheet 90 will be described as an example, but the present invention is not limited to this, and for example, a long roll-shaped sheet is wound up. You may pull out the sheet and use it.

The heating device 30 measures the temperature of the upper heater 10 that heats the upper surface 91b of the unmolded sheet 91, the lower heater 20 that heats the lower surface 91c of the unmolded sheet 91, and the upper temperature of the upper surface 91b of the unmolded sheet 91. It includes a sensor 13, a lower temperature sensor 23 that measures the temperature of the lower surface 91c of the unmolded sheet 91, and a heater control unit 52 (see FIG. 1). The heater control unit 52 has a circuit unit including a CPU and the like (not shown).

The heating device 30 (upper heater 10 and lower heater 20) operates under the control of the heater control unit 52 to heat the unmolded sheet 91 (sheet 90 before being molded by the molding device 40) to soften or melt it. Let me. When the upper heater 10 and the lower heater 20 are arranged at a position where the unmolded sheet 91 is heated by the heating device 30 (position shown in FIG. 4), the upper heater 10 is placed on the upper surface 91b of the unmolded sheet 91. It is located above and the lower heater 20 is provided below the lower surface 91c of the unmolded sheet 91.

Here, the upper heater 10 will be described. FIG. 2 is a plan view of the upper heater 10 and is a plan view of the upper heater 10 from the heat radiating portion 10b side that radiates heat. FIG. 3 is a plan view of the heater element 11 constituting the upper heater 10. The upper heater 10 has a plurality of heater elements 11 arranged adjacent to each other in the X direction (horizontal direction in FIG. 2) and the Y direction (vertical direction in FIG. 2). In the example shown in FIG. 2, the upper heater 10 has a total of 30 rows of heater elements 11 in which 6 heater elements 11 are arranged adjacent to each other in the X direction in 5 rows adjacent to each other in the Y direction. Has a heater element 11 of. These heater elements 11 constitute a heat radiating portion 10b.

The heater element 11 is a high-speed follow-up heater capable of rapid response and having a heating rate of 60 [° C./sec] or more at a rated voltage. As shown in FIG. 3, the heater element 11 has a substantially octagonal insulating plate 15 and a meandering heater element 16 arranged on the surface of the insulating plate 15. The heater element 16 includes a plurality of heating plates 17 arranged at intervals in one direction, and a plurality of connecting plates 18 for alternately connecting the ends of adjacent heating plates 17. The amount of heat generated by each heater element 11 is controlled by the amount of electric power supplied to each heater element 11. Therefore, the temperature of the upper heater 10 is controlled by the amount of electric power supplied to the heater element 11. The lower heater 20 also has the same configuration as the upper heater 10 described above (see FIGS. 2 and 3).

The upper temperature sensor 13 is a radiation thermometer and is arranged inside the upper heater 10. Specifically, the upper temperature sensor 13 is provided in the central region of the upper heater 10 so as to be surrounded by the four heater elements 11 located in the central region of the upper heater 10 in a plan view (FIG. 2). reference). The upper temperature sensor 13 measures the temperature of the upper surface 91b of the unmolded sheet 91 and outputs it as the sheet upper surface temperature T3.

Further, the lower temperature sensor 23 is a radiation thermometer and is arranged inside the lower heater 20. Specifically, the lower temperature sensor 23 is provided in the central region of the lower heater 20 so as to be surrounded by four heater elements 11 located in the central region of the lower heater 20 in a plan view. (See FIG. 2). The lower temperature sensor 23 measures the temperature of the lower surface 91c of the unmolded sheet 91 and outputs it as the sheet lower surface temperature T4.

Further, among the plurality of heater elements 11 included in the upper heater 10, a thermocouple thermometer 14 is attached to one heater element 11B located substantially in the center of the upper heater 10 in a plan view. The thermocouple thermometer 14 detects the temperature of the heater element 11B and outputs it as the temperature of the upper heater 10 (upper heater temperature T1). Further, among the plurality of heater elements 11 included in the lower heater 20, a thermocouple thermometer 24 is attached to one heater element 11B located substantially in the center of the lower heater 20 in a plan view. The thermocouple thermometer 24 detects the temperature of the heater element 11B and outputs it as the temperature of the lower heater 20 (lower heater temperature T2).

By the way, when the thermoplastic sheet 90 is heated, the sheet 90 is softened or melted by the heating, and the sheet 90 is deformed so as to hang down. More specifically, as the softening or melting of the sheet 90 progresses with the lapse of the heating time, the upper surface 90b of the sheet 90 moves away from the upper heater 10, and conversely, the lower surface 90c of the sheet 90 is the lower side. Approaching the heater 20.

In consideration of this, in the heating device 30 of the present embodiment, as shown in FIG. 4, the upper heater 10 and the lower heater 20 are located at positions where the unmolded sheet 91 is heated by the heating device 30 (FIG. 4). When it is arranged at the position shown in (1), the position between the upper heater 10 and the lower heater 20 (that is, when the heating of the unmolded sheet 91 is started), the upper heater 10 (the upper surface 91b of the unmolded sheet 91) The distance D1 between the heat radiating portion 10b facing the unmolded sheet 91 and the upper surface 91b of the unmolded sheet 91, the lower heater 20 (the heat radiating portion 20b facing the lower surface 91c of the unmolded sheet 91), and the lower surface 91c of the unmolded sheet 91. The distance D2 between the two is provided so as to satisfy the relationship D1 <D2. Specifically, the upper heater 10 and the lower heater 20 are located so that the distance D1 and the distance D2 satisfy the relationship of D1 <D2 when the heating of the sheet 90 is started, and the heating of the sheet 90 is performed. During the period, the sheets 90 are heated without changing their positions. By doing so, it is possible to prevent the sheet 90, which is deformed to hang downward due to heating, from coming into contact with the lower heater 20, and the upper heater 10 and the lower heater 20 make the sheet 90 more appropriate. Can be heated to. Note that FIG. 4 is a diagram showing the positional relationship between the upper heater 10, the lower heater 20, and the unmolded sheet 91 when the heating of the unmolded sheet 91 is started by the upper heater 10 and the lower heater 20. ..

The molding apparatus 40 operates under the control of the molding apparatus control unit 53, and forms the unmolded sheet 91 heated and softened by the heating apparatus 30. The molding apparatus 40 holds an upper mold 41 in which a cavity (not shown) corresponding to the shape of the molded product M is formed, a clamp 42, an upper table (not shown) for holding the upper mold 41, and a clamp 42. A lower table (not shown), a molding table drive mechanism (not shown) that holds the upper table and the lower table up and down, and a differential pressure supply mechanism (not shown) that generates a differential pressure in the cavity of the upper die 41. ) And.

In this molding apparatus 40, the unmolded sheet 91 is molded as follows under the control of the molding apparatus control unit 53 to produce a molded sheet 92 (sheet 90 including the molded product M). Specifically, when the unmolded sheet 91 softened by heating by the heating device 30 is carried in between the upper mold 41 and the clamp 42, the upper mold 41 and the clamp 42 arranged at the separated positions are moved. It moves to a close position by driving the molding table drive mechanism. The separation position is the position where the distance between the upper die 41 and the clamp 42 is the longest. Further, the proximity position is a position where the upper die 41 and the clamp 42 are closest to each other, and is a position where the unmolded sheet 91 is formed by the upper die 41 and the clamp 42.

When the upper die 41 and the clamp 42 are arranged at close positions, a differential pressure is generated in the cavity of the upper die 41 by the differential pressure supply mechanism, and the sheet 90 is brought into close contact with the upper die 41 by this differential pressure. As a result, the unmolded sheet 91 changes into a shape corresponding to the cavity of the upper mold 41 and becomes a molded sheet 92 (sheet 90 including the molded product M). After that, the upper mold 41 and the clamp 42 are moved to separate positions by driving the molding table drive mechanism, and the molded sheet 92 is taken out.

Next, the heater temperature control of the first embodiment will be described in detail. In the heating device 30 constituting the thermoforming device 1 of the first embodiment, the heater control unit 52 determines the temperatures of the upper heater 10 and the lower heater 20 based on the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23. To control.

Specifically, the heater control unit 52 inputs the sheet upper surface temperature T3 detected by the upper temperature sensor 13, and controls the temperature of the upper heater 10 based on the input sheet upper surface temperature T3. The heater control unit 52 controls the temperature of the upper heater 10 by adjusting the amount of electric power supplied to each heater element 11 of the upper heater 10. Further, the heater control unit 52 detects the temperature of the upper heater 10 by inputting the upper heater temperature T1 detected by the thermocouple thermometer 14.

Further, the heater control unit 52 inputs the seat lower surface temperature T4 detected by the lower temperature sensor 23, and controls the temperature of the lower heater 20 based on the input seat lower surface temperature T4. The heater control unit 52 controls the temperature of the lower heater 20 by adjusting the amount of electric power supplied to each heater element 11 of the lower heater 20. Further, the heater control unit 52 detects the temperature of the lower heater 20 by inputting the lower heater temperature T2 detected by the thermocouple thermometer 24.

The heater control unit 52 detects the sheet upper surface temperature T3 at regular time intervals so that the measured temperature of the upper temperature sensor 13 (that is, the sheet upper surface temperature T3) reaches the target temperature Tt, and the temperature of the upper heater 10 To control. Further, the heater control unit 52 detects the seat upper surface temperature T3 at regular time intervals so that the measured temperature of the lower temperature sensor 23 (that is, the seat lower surface temperature T4) reaches the target temperature Tt, and the upper heater 10 Control the temperature of. In the first embodiment, the target temperature Tt is set to 130 ° C. Therefore, in the present embodiment, the temperature of the upper surface 91b of the unmolded sheet 91 is raised to 130 ° C. by heating the upper heater 10 and the lower heater 20 controlled by the heater control unit 52, and the unmolded sheet 91 is heated. The temperature of the lower surface 91c of the above is also raised to 130 ° C., and the unmolded sheet 91 is softened.

More specifically, the heater control unit 52 starts heating the unmolded sheet 91 (sheet 90) by the upper heater 10 and the lower heater 20, and then the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23. Until the target temperature Tt is reached (that is, the seat upper surface temperature T3 and the seat lower surface temperature T4), the measured temperature of one of the upper temperature sensor 13 and the lower temperature sensor 23 is adjusted to the other measured temperature. As described above, the seat upper surface temperature T3 and the seat lower surface temperature T4 are raised to the target temperature Tt while controlling the temperatures of the upper heater 10 and the lower heater 20.

Specifically, the heater control unit 52 starts heating the unmolded sheet 91 (sheet 90) by the upper heater 10 and the lower heater 20, and then measures the measured temperatures (sheets) of the upper temperature sensor 13 and the lower temperature sensor 23. During the period until the top surface temperature T3 and the sheet bottom surface temperature T4) reach the target temperature Tt, one of the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23, which is set as the reference measurement temperature, is the other. While controlling the temperatures of the upper heater 10 and the lower heater 20, the seat upper surface temperature T3 and the seat lower surface temperature T4 are raised to the target temperature Tt so that the measured temperature of the above is followed. In other words, the heater control unit 52 makes the measured temperature of one of the upper temperature sensor 13 and the lower temperature sensor 23 set as the reference temperature sensor follow the measured temperature of the other temperature sensor. , The temperature of the upper heater 10 and the lower heater 20 is controlled to raise the seat upper surface temperature T3 and the seat lower surface temperature T4 to the target temperature Tt.

Specifically, in the first embodiment, the measured temperature of the lower temperature sensor 23 is set as the reference measured temperature, and the heater control unit 52 starts heating the unmolded sheet 91 at regular time intervals (for example, 1). (Every second), the sheet top surface temperature T3 and the sheet bottom surface temperature T4 are detected, and as shown in FIG. 5, the measurement temperature of the lower temperature sensor 23 set as the reference measurement temperature (that is, the sheet bottom surface temperature T4) is set. While controlling the temperatures of the upper heater 10 and the lower heater 20 at regular intervals so that the measured temperature of the upper temperature sensor 13 (that is, the seat upper surface temperature T3) follows, the seat upper surface temperature T3 and the seat lower surface temperature T4 are controlled. The temperature is raised to the target temperature Tt.

More specifically, the heater control unit 52 detects the sheet upper surface temperature T3 and the sheet lower surface temperature T4 at regular time intervals (for example, every 1 second), and is constant so that the sheet upper surface temperature T3 catches up with the sheet lower surface temperature T4. The temperature of the upper heater 10 is controlled every hour (the amount of electric power supplied to each heater element 11 of the upper heater 10 is adjusted). In other words, the heater control unit 52 sets the sheet lower surface temperature T4 detected at regular time intervals as a new temperature set value for the upper surface 91b of the unmolded sheet 91, so that the sheet upper surface temperature T3 becomes this temperature set value. In addition, the temperature of the upper heater 10 is controlled at regular intervals (the amount of electric power supplied to each heater element 11 of the upper heater 10 is adjusted). At this time, the heater control unit 52 controls the temperature of the lower heater 20 so that the seat lower surface temperature T4 approaches the target temperature Tt (adjusts the amount of electric power supplied to each heater element 11 of the lower heater 20). ..

FIG. 5 is a diagram illustrating the heater temperature control according to the first embodiment, from the start of heating of the unmolded sheet 91 (sheet 90) by the upper heater 10 and the lower heater 20 to the end of heating. The temperature fluctuations (changes in temperature) of the upper heater temperature T1, the lower heater temperature T2, the seat upper surface temperature T3, and the seat lower surface temperature T4 are shown. In FIG. 5, the upper heater temperature T1 is indicated by a dashed line, the lower heater temperature T2 is indicated by a broken line, the sheet upper surface temperature T3 is indicated by a thick solid line, and the sheet lower surface temperature T4 is indicated by a thin solid line.

By heating the unmolded sheet 91 (sheet 90) while controlling the temperatures of the upper heater 10 and the lower heater 20 in this way, as shown in FIG. 5, the sheet is started after the heating of the unmolded sheet 91 is started. The temperature fluctuation (change in temperature) of the upper surface 91b of the unmolded sheet 91 and the temperature fluctuation (change in temperature) of the lower surface 91c in the period until the upper surface temperature T3 and the lower surface temperature T4 of the sheet reach the target temperature Tt. The difference can be small. In other words, the temperature fluctuation (temperature change) of the upper surface 91b of the unmolded sheet 91 during the period from the start of heating the unmolded sheet 91 until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. (Transition) and the temperature fluctuation (transition of temperature change) of the lower surface 91c can be made substantially the same.

As a result, the difference in temperature distribution in the thickness direction (vertical direction in FIG. 4) becomes small between the upper half and the lower half of the sheet 90 (unmolded sheet 91) at the end of heating. That is, the difference between the temperature distribution from the upper surface 91b of the unmolded sheet 91 to the central portion 91d in the thickness direction and the temperature distribution from the lower surface 91c of the unmolded sheet 91 to the central portion 91d in the thickness direction can be reduced. Further, when a plurality of unmolded sheets 91 are sequentially heated by the heating device 30, the temperature fluctuation (change in temperature) of the upper surface 91b of the unmolded sheet 91 and the temperature of the lower surface 91c among the plurality of unmolded sheets 91. The difference in fluctuation (transition of temperature change) becomes small, and the difference in temperature distribution in the thickness direction of the unmolded sheet 91 also becomes small among the plurality of unmolded sheets 91.

Therefore, in the first embodiment, the difference in the degree of softening (softening degree) between the upper half and the lower half of the sheet 90 (unmolded sheet 91) at the end of heating becomes small (in other words, the softening degree). Is almost equivalent). Further, even among the plurality of sheets 90 sequentially heated by the heating device 30, the difference in the degree of softening of the sheets 90 in the thickness direction becomes small. Therefore, when the sheet 90 is subsequently molded by the molding apparatus 40, the difference in the degree of deformation (elongation) of the sheets 90 between the sheets 90 becomes small, and the quality of the molded product M becomes stable (molding failure of the sheet 90). Can also be reduced).

Further, in the present embodiment, as shown in FIG. 5, in the heater control unit 52, the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23 (that is, the sheet upper surface temperature T3 and the sheet lower surface temperature T4) are the target temperatures Tt. After reaching, the temperatures of the upper heater 10 and the lower heater 20 are maintained at the target temperature Tt so that the measured temperatures (seat upper surface temperature T3 and seat lower surface temperature T4) of the upper temperature sensor 13 and the lower temperature sensor 23 are maintained at the target temperature Tt. (That is, the upper heater temperature T1 and the lower heater temperature T2) are controlled.

By doing so, it is possible to further reduce the difference in temperature distribution in the thickness direction between the upper half and the lower half of the sheet 90 at the end of heating. That is, the difference between the temperature distribution from the upper surface 90b of the sheet 90 to the central portion 90d in the thickness direction and the temperature distribution from the lower surface 90c of the sheet 90 to the central portion 90d in the thickness direction can be further reduced. Further, when a plurality of sheets are sequentially heated by the heating device 30, the temperature fluctuation of the upper surface 90b of the sheet 90 (change in temperature) and the temperature fluctuation of the lower surface 90c (change in temperature) among the plurality of sheets 90. The difference between the two sheets 90 becomes even smaller, and the difference in the temperature distribution in the thickness direction of the sheets 90 becomes even smaller among the plurality of sheets 90.

As a result, the difference in the degree of softening (softening degree) between the upper half and the lower half of the sheet 90 (unmolded sheet 91) at the end of heating (before molding) can be further reduced (in other words, the degree of softening). , The degree of softening can be made almost the same). Further, the difference in the degree of softening in the thickness direction of the sheets 90 is further reduced among the plurality of sheets 90 sequentially heated by the heating device 30. Therefore, when the sheet 90 is subsequently molded by the molding apparatus 40, the difference in the degree of deformation (elongation) of the sheets 90 between the sheets 90 becomes smaller, and the quality of the molded product M becomes more stable (sheet). Molding defects of 90 can be further reduced).

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to the drawings. In the second embodiment, the temperature control of the upper heater and the lower heater by the heater control unit is different from that in the first embodiment, and the others are the same. Therefore, here, the points different from those of the first embodiment will be mainly described, and the description of the same points will be omitted or simplified. As shown in FIG. 1, the thermoforming apparatus 101 according to the second embodiment includes a molding apparatus 40 similar to that of the first embodiment and a heating apparatus 130 different from the first embodiment. The heating device 130 of the second embodiment is different from the heating device 30 of the first embodiment only in the heater control unit 152, and the others are the same.

Hereinafter, the heater temperature control of the second embodiment will be described in detail. In the thermoforming device 101 (heating device 130) of the second embodiment, the heater control unit 152 measures the temperatures of the upper heater 10 and the lower heater 20 based on the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23. Control. Specifically, the heater control unit 152 starts heating the unmolded sheet 91 (sheet 90) by the upper heater 10 and the lower heater 20, and then the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23 ( That is, until the seat upper surface temperature T3 and the seat lower surface temperature T4) reach the target temperature Tt, the measured temperature of one of the upper temperature sensor 13 and the lower temperature sensor 23 is adjusted to the other measured temperature. In addition, the seat upper surface temperature T3 and the seat lower surface temperature T4 are raised to the target temperature Tt while controlling the temperatures of the upper heater 10 and the lower heater 20.

Specifically, the heater control unit 152 starts heating the unmolded sheet 91 (sheet 90) by the upper heater 10 and the lower heater 20, and then measures the measured temperatures (sheets) of the upper temperature sensor 13 and the lower temperature sensor 23. During the period until the upper surface temperature T3 and the lower surface temperature T4) reach the target temperature Tt, the measured temperature of the upper temperature sensor 13 (seat upper surface temperature T3) and the measured temperature of the lower temperature sensor 23 (seat lower surface temperature T4) The sheet upper surface temperature T3 and the sheet lower surface temperature T4 are controlled while controlling the temperatures of the upper heater 10 and the lower heater 20 so that the measured temperature of the higher temperature or the lower temperature is matched with the measured temperature of the other. The temperature is raised to the target temperature Tt.

Specifically, in the second embodiment, as shown in FIG. 6, after the unmolded sheet 91 is started to be heated by the upper heater 10 and the lower heater 20, the sheet upper surface temperature T3 and the sheet lower surface temperature T4 are the targets. During the period until the temperature reaches Tt, the heater control unit 152 sets the measured temperature of the upper temperature sensor 13 (seat upper surface temperature T3) and the measured temperature of the lower temperature sensor 23 (seat lower surface temperature T4) at regular time intervals (seat lower surface temperature T4). For example, every 1 second), while controlling the temperatures of the upper heater 10 and the lower heater 20 so that the measured temperature of the higher temperature is matched with the measured temperature of the lower temperature, the sheet upper surface temperature T3 and The sheet bottom surface temperature T4 is raised to the target temperature Tt.

More specifically, when the heater control unit 52 compares the detected sheet upper surface temperature T3 and the sheet lower surface temperature T4 and determines that T3> T4, the sheet upper surface temperature T3, which is a high temperature, is determined. The temperature of the upper heater 10 is controlled so that the temperature of the lower surface of the sheet is T4, which is a low temperature (the amount of power supplied to each heater element 11 of the upper heater 10 is adjusted). At this time, the heater control unit 52 controls the temperature of the lower heater 20 so that the seat lower surface temperature T4 approaches the target temperature Tt (adjusts the amount of electric power supplied to each heater element 11 of the lower heater 20). ..

On the contrary, when it is determined that T3 <T4, the heater control unit 52 sets the lower heater 20 so that the high temperature sheet lower surface temperature T4 becomes the low temperature sheet upper surface temperature T3. The temperature is controlled (the amount of electric power supplied to each heater element 11 of the lower heater 20 is adjusted). At this time, the heater control unit 52 controls the temperature of the upper heater 10 so that the seat upper surface temperature T3 approaches the target temperature Tt (adjusts the amount of electric power supplied to each heater element 11 of the upper heater 10).

In the second embodiment, as shown in FIG. 6, the measured temperature (seat upper surface temperature T3) of the upper temperature sensor 13 is high until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. By the heater control unit 152, the time when the measured temperature of the lower temperature sensor 23 becomes the measured temperature and the time when the measured temperature of the lower temperature sensor 23 (the sheet upper surface temperature T3) becomes the higher temperature is alternately repeated. The temperatures of the upper heater 10 and the lower heater 20 are controlled. That is, until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt, the measured temperature of the upper temperature sensor 13 (seat upper surface temperature T3) and the measured temperature of the lower temperature sensor 23 (seat upper surface temperature T3). The temperature of the upper heater 10 and the lower heater 20 is controlled by the heater control unit 152 so that the relationship between the temperature and the temperature is not constant (one is always high temperature and the other is low temperature) but alternates with each other (see FIG. 6). ).

FIG. 6 is a diagram for explaining the heater temperature control according to the second embodiment, from the start of heating of the unmolded sheet 91 (sheet 90) by the upper heater 10 and the lower heater 20 to the end of heating. The temperature fluctuations (changes in temperature) of the upper heater temperature T1, the lower heater temperature T2, the seat upper surface temperature T3, and the seat lower surface temperature T4 are shown. In FIG. 6, the upper heater temperature T1 is indicated by a dashed line, the lower heater temperature T2 is indicated by a broken line, the sheet upper surface temperature T3 is indicated by a thick solid line, and the sheet lower surface temperature T4 is indicated by a thin solid line.

By heating the unmolded sheet 91 (sheet 90) while controlling the temperatures of the upper heater 10 and the lower heater 20 in this way, as shown in FIG. 6, the sheet is started after the heating of the unmolded sheet 91 is started. The temperature fluctuation (change in temperature) of the upper surface 91b of the unmolded sheet 91 and the temperature fluctuation (change in temperature) of the lower surface 91c in the period until the upper surface temperature T3 and the lower surface temperature T4 of the sheet reach the target temperature Tt. The difference can be small. In other words, the temperature fluctuation (temperature change) of the upper surface 91b of the unmolded sheet 91 during the period from the start of heating the unmolded sheet 91 until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. (Transition) and the temperature fluctuation (transition of temperature change) of the lower surface 91c can be made substantially the same.

As a result, the difference in temperature distribution in the thickness direction between the upper half and the lower half of the sheet 90 (unmolded sheet 91) at the end of heating becomes small. That is, the difference between the temperature distribution from the upper surface 91b of the unmolded sheet 91 to the central portion 91d in the thickness direction and the temperature distribution from the lower surface 91c of the unmolded sheet 91 to the central portion 91d in the thickness direction can be reduced. Further, when a plurality of unmolded sheets 91 are sequentially heated by the heating device 130, the temperature fluctuation (change in temperature) of the upper surface 91b of the unmolded sheet 91 and the temperature of the lower surface 91c among the plurality of unmolded sheets 91. The difference in fluctuation (transition of temperature change) becomes small, and the difference in temperature distribution in the thickness direction of the unmolded sheet 91 also becomes small among the plurality of unmolded sheets 91.

Therefore, even in the second embodiment, the difference in the degree of softening (softening degree) between the upper half and the lower half of the sheet 90 (unmolded sheet 91) at the end of heating becomes small (in other words, the softening degree). Is almost equivalent). Further, even among the plurality of sheets 90 sequentially heated by the heating device 130, the difference in the degree of softening in the thickness direction of the sheets 90 becomes small. Therefore, when the sheet 90 is subsequently molded by the molding apparatus 40, the difference in the degree of deformation (elongation) of the sheets 90 between the sheets 90 becomes small, and the quality of the molded product M becomes stable (molding failure of the sheet 90). Can also be reduced).

Further, as shown in FIG. 6, the heater control unit 152 receives after the measured temperatures of the upper temperature sensor 13 and the lower temperature sensor 23 (that is, the seat upper surface temperature T3 and the seat lower surface temperature T4) reach the target temperature Tt. The temperatures of the upper heater 10 and the lower heater 20 (that is, the upper heater) so that the measured temperatures (seat upper surface temperature T3 and seat lower surface temperature T4) of the upper temperature sensor 13 and the lower temperature sensor 23 are maintained at the target temperature Tt. The temperature T1 and the lower heater temperature T2) are controlled.

By doing so, it is possible to further reduce the difference in temperature distribution in the thickness direction between the upper half and the lower half of the sheet 90 at the end of heating. Further, when a plurality of sheets 90 are sequentially heated by the heating device 130, the temperature fluctuation of the upper surface 90b of the sheet 90 (change in temperature) and the temperature fluctuation of the lower surface 90c (change in temperature) between the plurality of sheets 90. ) Is further reduced, and the difference in temperature distribution in the thickness direction of the sheets 90 is further reduced among the plurality of sheets 90.

As a result, the difference in the degree of softening (softening degree) between the upper half and the lower half of the sheet 90 (unmolded sheet 91) at the end of heating (before molding) can be further reduced (in other words, the degree of softening). , The degree of softening can be made almost the same). Further, the difference in the degree of softening in the thickness direction of the sheets 90 is further reduced among the plurality of sheets 90 sequentially heated by the heating device 30. Therefore, when the sheet 90 is subsequently molded by the molding apparatus 40, the difference in the degree of deformation (elongation) of the sheets 90 between the sheets 90 becomes smaller, and the quality of the molded product M becomes more stable (sheet). Molding defects of 90 can be further reduced).

Although the present invention has been described above with reference to the first and second embodiments, the present invention is not limited to the first and second embodiments, and can be appropriately modified and applied without departing from the gist thereof. Needless to say.

For example, in the first embodiment, the measurement temperature of the lower temperature sensor 23 is set as the reference measurement temperature, the heating of the unmolded sheet 91 is started by the upper heater 10 and the lower heater 20, and then the sheet upper surface temperature T3 and the sheet are started. During the period until the lower surface temperature T4 reaches the target temperature Tt, the measured temperature of the lower temperature sensor 23 (that is, the sheet lower surface temperature T4) set as the reference measurement temperature is set to the measured temperature of the upper temperature sensor 13 (that is, that is). The temperatures of the upper heater 10 and the lower heater 20 are controlled so that the seat upper surface temperature T3) follows (see FIG. 5).

However, on the contrary, the measurement temperature of the upper temperature sensor 13 is set as the reference measurement temperature, and the measurement temperature of the upper temperature sensor 13 (sheet upper surface temperature T3) set as the reference measurement temperature is set to the lower temperature sensor 23. The temperatures of the upper heater 10 and the lower heater 20 may be controlled so that the measured temperature (seat lower surface temperature T4) of the above is followed. For example, the sheet upper surface temperature T3 and the sheet lower surface temperature T4 are detected at regular time intervals (for example, every 1 second), and the temperature of the upper heater 10 is controlled at regular time intervals so that the sheet upper surface temperature T3 catches up with the sheet lower surface temperature T4. (Adjust the amount of electric power supplied to each heater element 11 of the upper heater 10).

Even when controlled in this way, the temperature fluctuation of the upper surface 91b of the unmolded sheet 91 during the period from the start of heating of the unmolded sheet 91 until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. The difference between (transition of temperature change) and temperature fluctuation of the lower surface 91c (transition of temperature change) can be reduced. In other words, the temperature fluctuation (temperature change) of the upper surface 91b of the unmolded sheet 91 during the period from the start of heating the unmolded sheet 91 until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. (Transition) and the temperature fluctuation (transition of temperature change) of the lower surface 91c can be made substantially the same.

Further, in the second embodiment, as shown in FIG. 6, after the heating of the unmolded sheet 91 is started by the upper heater 10 and the lower heater 20, the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. During the period until the temperature is increased, the measured temperature of the upper temperature sensor 13 (seat upper surface temperature T3) and the measured temperature of the lower temperature sensor 23 (seat lower surface temperature T4) are compared at regular intervals to measure the higher temperature. The temperatures of the upper heater 10 and the lower heater 20 are controlled so that the temperature is adjusted to the measured temperature of the lower temperature.

However, on the contrary, the temperatures of the upper heater 10 and the lower heater 20 may be controlled so as to match the measured temperature of the lower temperature side with the measured temperature of the higher temperature side. For example, when the detected sheet upper surface temperature T3 and the sheet lower surface temperature T4 are compared and T3> T4, the lower sheet lower temperature T4 becomes the high temperature sheet upper surface temperature T3 when T3> T4. The temperature of the heater 20 may be controlled (the amount of power supplied to each heater element 11 of the lower heater 20 may be adjusted). On the contrary, when T3 <T4, the temperature of the upper heater 10 is controlled so that the low temperature sheet upper surface temperature T3 becomes the high temperature sheet lower surface temperature T4 (each heater element of the upper heater 10). The amount of electric power supplied to 11 may be adjusted).

Even when controlled in this way, the temperature fluctuation of the upper surface 91b of the unmolded sheet 91 during the period from the start of heating of the unmolded sheet 91 until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. The difference between (transition of temperature change) and temperature fluctuation of the lower surface 91c (transition of temperature change) can be reduced. In other words, the temperature fluctuation (temperature change) of the upper surface 91b of the unmolded sheet 91 during the period from the start of heating the unmolded sheet 91 until the sheet upper surface temperature T3 and the sheet lower surface temperature T4 reach the target temperature Tt. (Transition) and the temperature fluctuation (transition of temperature change) of the lower surface 91c can be made substantially the same.

Further, in the first and second embodiments, the positions of the heating device 30 (upper heater 10 and lower heater 20) are fixed, and the sheet 90 is supplied to the heating device 30 whose positions are fixed. However, on the contrary, the position of the sheet 90 may be fixed and the heating device 30 (upper heater 10 and lower heater 20) may be moved to the position where the sheet 90 is heated. The same applies to the molding apparatus 40.

Further, in the first and second embodiments, as shown in FIG. 4, the upper heater 10 and the lower heater 20 are provided so as to satisfy the relationship of D1 <D2. However, the present invention can also be applied when D1 = D2 and D1> D2.

Further, in the first and second embodiments, examples of heating the sheet 90 made of a thermoplastic resin by the heating devices 30 and 130 to soften or melt the sheet 90 are shown, and the heating device of the present invention heats such a sheet. Not limited to things. For example, the heating device of the present invention can also be applied to a case where a carbon fiber sheet impregnated with a liquid thermosetting resin is heated to cure the thermosetting resin to form a carbon fiber composite sheet. ..

Even in this case, the temperature fluctuations on the upper surface (change in temperature) and the temperature fluctuations on the lower surface of the sheet during the period from the start of heating of the sheet until the temperature T3 on the upper surface of the sheet and the temperature T4 on the lower surface of the sheet reach the target temperature Tt. The difference from (transition of temperature change) can be reduced. Furthermore, when a plurality of sheets are heated in order, the difference between the temperature fluctuation (change in temperature change) on the upper surface of the sheet and the temperature fluctuation (change in temperature change) on the lower surface becomes smaller among the plurality of sheets, and a plurality of sheets are heated. The difference in temperature distribution in the thickness direction of the sheets between the sheets is also small. This makes it possible to reduce the difference in the degree of curing of the thermosetting resin between the upper portion (upper half) and the lower portion (lower half) of the sheet. Furthermore, it is possible to reduce the difference in the degree of curing of the resin in the thickness direction of the sheets even among the plurality of sheets that have been sequentially heated. Thereby, the quality of the formed carbon fiber composite sheet can be stabilized.

1,101 Thermoforming device 10 Upper heater 11 Heater element 13 Upper temperature sensor 20 Lower heater 23 Lower temperature sensor 30, 130 Heating device 40 Molding device 52, 152 Heater control unit 90 Sheet 90b, 91b Upper surface 90c, 91c Lower surface 91 Unmolded sheet 92 Molded sheet D1 Distance between the upper heater and the upper surface of the sheet D2 Distance between the lower heater and the lower surface of the sheet Tt Target temperature

Claims (6)

In a heating device that heats the sheet
An upper heater that heats the upper surface of the sheet and
A lower heater that heats the lower surface of the sheet and
An upper temperature sensor that measures the temperature of the upper surface of the sheet, and
A lower temperature sensor that measures the temperature of the lower surface of the sheet, and
A heater control unit that controls the temperature of the upper heater and the lower heater based on the measured temperatures of the upper temperature sensor and the lower temperature sensor is provided.
The heater control unit starts heating the sheet by the upper heater and the lower heater until the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. A heating device that controls the temperatures of the upper heater and the lower heater so that the measured temperature of one of the measured temperatures of the temperature sensor and the lower temperature sensor matches the measured temperature of the other. The heating device according to claim 1.
The upper heater and the lower heater have a distance D1 between the upper heater and the upper surface of the sheet when the heating of the sheet is started, and the lower heater and the lower surface of the sheet. A heating device provided so that the distance D2 between them satisfies the relationship D1 <D2. The heating device according to claim 1 or 2.
The heater control unit starts heating the sheet by the upper heater and the lower heater until the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. The temperatures of the upper heater and the lower heater are controlled so that the measured temperature of one of the measured temperatures of the upper temperature sensor and the lower temperature sensor, which is set as the reference measured temperature, is followed by the measured temperature of the other. Heating device. The heating device according to claim 1 or 2.
The heater control unit starts heating the sheet by the upper heater and the lower heater until the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. By comparing the measured temperature of the upper temperature sensor with the measured temperature of the lower temperature sensor, the upper heater and the lower heater so as to match the measured temperature of the higher temperature or the lower temperature with the measured temperature of the other. A heating device that controls the temperature. The heating device according to any one of claims 1 to 4.
The heater control unit keeps the measured temperatures of the upper temperature sensor and the lower temperature sensor at the target temperature after the measured temperatures of the upper temperature sensor and the lower temperature sensor reach the target temperature. A heating device that controls the temperature of the upper heater and the lower heater. The heating device according to any one of claims 1 to 5.
A thermoforming apparatus comprising a molding apparatus for molding the sheet heated by the heating apparatus.

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