Film heating device, film stretcher, film manufacturing device, and film heating control method

Abstract

To provide an excellent film heating device. [Solution] A film heating device according to one embodiment includes at least one pair of nozzles that extend from a plenum box in the width direction of the resin film and are arranged facing each other via the resin film, and that send air contained in the plenum box toward the resin film; a temperature sensor that measures the temperature of the air heated by the heater; and a controller that provides feedback control of the heater based on the temperature measured by the temperature sensor.

Description

Technical Field

[0001] The present invention relates to a film heating device, a film stretching machine, a film manufacturing device, and a film heating control method.

Background Art

[0002] As disclosed in Patent Document 1, the inventors have developed a resin film manufacturing device equipped with a film stretching machine such as a transverse stretching machine or a simultaneous biaxial stretching machine. In such a film stretching machine, while heating the resin film by sending out the heated air in the film heating device, the resin film is stretched.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors have found various problems in the development of a film stretching machine equipped with a film heating device. For example, the quality of the resin film to be stretched depends on the temperature of the resin film heated by the film heating device, that is, the temperature of the air sent toward the resin film.

[0005] However, for example, in a film heating device, if the heater is feedback-controlled based on the temperature of the plenum box that houses the heated air, the temperature of the air sent out from the film heating device cannot be accurately grasped. Therefore, in order to stabilize the quality of the resin film to be stretched, it may take a long time and waste the resin material. Other problems and novel features will become apparent from the description of this specification and the accompanying drawings.

Means for Solving the Problems

[0006] A film heating apparatus according to one embodiment is described as follows: A pair of nozzles extending from the plenum box in the width direction of the resin film and positioned opposite each other via the resin film, which deliver air contained in the plenum box toward the resin film, A temperature sensor that measures the temperature of air heated by a heater, The system includes a controller that provides feedback control of the heater based on the temperature measured by a temperature sensor.

[0007] A film heating control method according to one embodiment is: A film heating control method for controlling the heating of a conveyed resin film by a film heating device, The aforementioned film heating device is A pair of nozzles extending from the plenum box in the width direction of the resin film and positioned opposite each other via the resin film, which deliver air contained in the plenum box toward the resin film, It includes a temperature sensor that measures the temperature of heated air, Computers (a) A step of providing feedback control to the heater based on the temperature measured by a temperature sensor. [Effects of the Invention]

[0008] According to the above embodiment, an excellent film heating device can be provided. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic perspective view showing the overall configuration of the resin film manufacturing apparatus according to the first embodiment. [Figure 2] This is a schematic cross-sectional view showing the overall configuration of a resin film manufacturing apparatus according to the first embodiment. [Figure 3] This is a schematic side view showing the configuration of the transverse stretching machine 50 according to the first embodiment. [Figure 4] It is a sectional view taken along the cutting line IV-IV in FIG. 3. [Figure 5] It is a partial top view showing the configuration of the film heating device 51. [Figure 6] It is a schematic side view showing the configuration of the film heating device 51 according to a modification of the first embodiment. [Figure 7] It is a block diagram showing the configuration of the controller 70 according to the second embodiment. [Figure 8] It is a flowchart showing the control method of the film heating control method according to the second embodiment. [Figure 9] It is a block diagram showing the configuration of the controller 70 according to a modification of the second embodiment. [Figure 10] It is a schematic side view showing the configuration of the film heating device 51 according to the third embodiment. [Figure 11] It is a sectional view taken along the cutting line XI-XI in FIG. 10. [Figure 12] It is a schematic side view showing the configuration of the film heating device 51 according to Modification 1 of the third embodiment. [Figure 13] It is a schematic side view showing the configuration of the film heating device 51 according to Modification 2 of the third embodiment. [Figure 14] It is a schematic side view showing the configuration of the film heating device 51 according to the fourth embodiment. [Figure 15] It is a flowchart showing the film heating control method according to the fourth embodiment. <​​​​​​​​​​​​​​​The following describes specific embodiments in detail with reference to the drawings. However, the embodiments are not limited to those described below. Also, for clarity, the following descriptions and drawings have been simplified as appropriate.

[0011] (First embodiment) <Overall configuration of resin film manufacturing equipment> First, the overall configuration of the resin film manufacturing apparatus according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic perspective view showing the overall configuration of the resin film manufacturing apparatus according to the first embodiment. Figure 2 is a schematic cross-sectional view showing the overall configuration of the resin film manufacturing apparatus according to the first embodiment.

[0012] It should be noted that the right-handed XYZ Cartesian coordinate system shown in Figure 1 and other drawings is merely a convenient representation for explaining the positional relationships of the components. Typically, the positive Z-axis is vertically upward, and the XY plane is horizontal, and this is consistent across all drawings. Furthermore, in this specification, the term "resin film" includes "resin sheet."

[0013] As shown in Figures 1 and 2, the resin film manufacturing apparatus according to the first embodiment comprises an extruder 10, a T-die 20, a casting machine 30, a longitudinal stretcher 40, a transverse stretcher 50, a winding machine 60, and a controller 70. The resin film manufacturing apparatus according to the first embodiment is an extrusion molding type resin film manufacturing apparatus that extrudes a film-like molten resin 82a from the gap between the lips of the T-die 20 connected to the extruder 10. Note that the controller 70 is omitted in Figure 1.

[0014] The extruder 10 illustrated in Figures 1 and 2 is a screw-type extruder. As shown in Figure 2, in the extruder 10, a screw 12 extending in the X-axis direction is housed inside a cylinder 11 extending in the X-axis direction.

[0015] As shown in Figure 2, a screw motor SM is connected to the base of the screw 12. The screw motor SM is the drive source for driving the screw 12 and is controlled by the controller 70. Note that the number of screws 12 can be singular or plural. For example, an extruder 10 with one screw 12 is called a single-screw extruder, and an extruder 10 with two screws 12 is called a twin-screw extruder.

[0016] A hopper 13 is provided above the negative X-axis end of the cylinder 11 for feeding in the resin raw material 81, which is the raw material for the resin film 83. The resin raw material 81 is, for example, resin pellets or resin powder. As shown in Figure 2, a raw material feeder 14 is installed above the hopper 13 to supply the resin raw material 81 into the cylinder 11. The raw material feeder 14 is of the screw type and includes a feeder hopper FH, a feeder screw FS, and a feeder motor FM. Furthermore, the drive method for the raw material feeder 14 is not limited in any way; a belt drive, a combination drive combining a screw drive and a belt drive, etc., are also acceptable.

[0017] Resin raw material 81 is fed into and stored in the feeder hopper FH. When the feeder screw FS is rotated by the feeder motor FM, the resin raw material 81 in the feeder hopper FH is supplied to the inside of the cylinder 11 via the hopper 13. For example, the controller 70 provides feedback control of the rotation of the feeder motor FM while monitoring the mass change of the resin raw material 81 in the feeder hopper FH. With this configuration, the amount of resin raw material 81 supplied from the raw material feeder 14 to the extruder 10 can be controlled. Multiple raw material feeders 14 may be provided.

[0018] The resin material 81 supplied from the hopper 13 into the cylinder 11 is conveyed from the base to the tip of the rotating screw 12, that is, in the positive X-axis direction. Here, although not shown in the figure, a heater is provided on the outer surface of the cylinder 11 over substantially the entire lengthwise area to heat the inside of the cylinder 11, and the resin material 81 introduced into the cylinder 11 is heated. In this way, the resin material 81 is heated inside the cylinder 11 and sheared and melted by the rotating screw 12, transforming into molten resin 82.

[0019] As shown in Figures 1 and 2, the T-die 20 is connected to the underside of the tip (positive X-axis end) of the extruder 10. The film-like molten resin 82a is extruded downward (negative Z-axis direction) through the gap in the lip located at the lower end of the T-die 20. Here, the lip spacing of the T-die 20 can be adjusted. For example, the lip spacing of the T-die 20 can be adjusted at multiple locations along the longitudinal direction (Y-axis direction) of the lip so that the thickness of the manufactured resin film 83 is uniform in the width direction (Y-axis direction).

[0020] Here, as shown in Figure 2, a gear pump GP is provided in the horizontal section of the piping connecting the extruder 10 and the T-die 20. The gear pump GP sucks in the molten resin extruded from the extruder 10 and sends it to the T-die 20. The gear pump GP is composed of, for example, a pair of gears that mesh with each other. One of the gears of the gear pump GP is driven by a motor (not shown). Furthermore, the pump that sucks in the molten resin extruded from the extruder 10 and sends it to the T-die 20 is not limited to a gear pump; other types of pumps may also be used. In addition, there may be multiple extruders 10 and gear pumps GP that supply the molten resin 82 to the T-die 20.

[0021] As shown in Figure 2, a pressure sensor PS is provided on the suction side of the gear pump GP in the piping connecting the extruder 10 and the T-die 20. The pressure sensor PS measures the pressure of the molten resin on the suction side of the gear pump GP. The measured pressure measured by the pressure sensor PS is input to the controller 70.

[0022] As shown in Figures 1 and 2, the casting machine 30 is equipped with a casting roll CS and a cooling roll CR. The cast roll CS cools the film-like molten resin 82a extruded from the T-die 20, while simultaneously transferring the solidified resin film 83 from the film-like molten resin 82a to the cooling roll CR.

[0023] As shown in Figures 1 and 2, the cooling roll CR cools and transports the resin film 83. The cast roll CS and the cooling roll CR are drive rolls, each driven by a drive source (not shown). The drive source is, for example, a variable-speed motor such as a servo motor.

[0024] Furthermore, the cast roll CS and the cooling roll CR may each be equipped with a cooling mechanism for cooling the resin film 83. Also, the cast roll CS and the cooling roll CR may each be equipped with a heating mechanism for heating the resin film 83. Furthermore, the casting machine 30 may include multiple cast rolls CS and multiple cooling rolls CR.

[0025] As shown in Figures 1 and 2, the longitudinal stretcher 40 stretches the resin film 83 discharged from the casting machine 30 in the longitudinal direction while transporting it. The longitudinal stretcher 40 illustrated in Figures 1 and 2 is equipped with five rolls R1 to R5. Each of the rolls R1 to R5 is a drive roll driven by a drive source (not shown). The drive source is, for example, a variable speed motor such as a servo motor.

[0026] The longitudinal stretching machine 40 only needs to be equipped with multiple drive rolls for transporting the resin film 83, and the number and arrangement of the drive rolls equipped in the longitudinal stretching machine 40 can be determined as appropriate. Furthermore, each of the rolls R1 to R5 may be equipped with at least one of a cooling mechanism for cooling the resin film 83 and a heating mechanism for heating the resin film 83. Furthermore, the longitudinal stretcher 40 may be equipped with one or more nip rolls for pressing the resin film 83 against any of the rolls R1 to R5. The nip rolls are not drive rolls. Furthermore, the vertical extension machine 40 is not essential.

[0027] As shown in Figure 1, the transverse stretcher 50 stretches the resin film 83 discharged from the longitudinal stretcher 40 in its width direction (Y-axis direction). More specifically, as shown in Figure 1, the transverse stretcher 50 is equipped with a pair of rails RL1 and RL2. Numerous clips (not shown) are slidably arranged along the entire length of the rails RL1 and RL2. The drive source for sliding the clips is, for example, a variable-speed motor such as a servo motor.

[0028] In Figure 1, the arrows indicated on rails RL1 and RL2 show the direction of movement of the clips. As shown in Figure 1, rails RL1 and RL2 have a loop structure with a forward path in which the clips move in the direction of transport of the resin film 83 (positive X-axis direction) and a return path in the opposite direction (negative X-axis direction). In other words, in the lateral stretching machine 50, the clips revolve along rails RL1 and RL2, which have a loop structure. As shown in Figure 1, rails RL1 and RL2 have a symmetrical configuration with respect to a plane parallel to the XZ plane.

[0029] As shown in Figure 1, in rails RL1 and RL2, the forward path, which moves in the transport direction (positive X-axis direction), and the return path, which moves in the opposite direction (negative X-axis direction), are provided approximately parallel to each other. The return path of rail RL1 is provided on the outside in the width direction of the resin film 83 (negative Y-axis direction side). The return path of rail RL2 is also provided on the outside in the width direction of the resin film 83 (positive Y-axis direction side).

[0030] As shown in Figure 1, the forward paths of rails RL1 and RL2 are provided with a pair of parallel sections parallel to the X-axis at both ends in the longitudinal direction (X-axis direction), and a slanted section between the two parallel sections that is oblique in the Y-axis direction. The slanted section of rail RL1 is oblique in the negative Y-axis direction, and the slanted section of rail RL2 is oblique in the positive Y-axis direction. That is, in the slanted sections of the forward paths of rails RL1 and RL2, the distance between rail RL1 and rail RL2 in the Y-axis direction widens as they advance in the positive X-axis direction.

[0031] In the forward path of rails RL1 and RL2 shown in Figure 1, the clips grip both ends of the resin film 83 in the width direction (Y-axis direction) while moving along rails RL1 and RL2 in the positive X-axis direction. Therefore, as shown in Figure 1, in the slanted section of the forward path of rails RL1 and RL2, the resin film 83 is transported in the positive X-axis direction while being stretched in the width direction (Y-axis direction). Thus, rails RL1 and RL2 and the clips constitute a transport device for transporting the resin film 83.

[0032] In the rails RL1 and RL2 shown in Figure 1, in the portions where the clip is not in contact with the resin film 83, the clip moves along the rails RL1 and RL2 without gripping the resin film 83. More specifically, the clip grips the resin film 83 at the entrance of the transverse stretching machine 50, i.e., the rear ends (negative X-axis ends) of the rails RL1 and RL2, and moves along the rails RL1 and RL2 in the positive X-axis direction while gripping the resin film 83. Then, the clip releases the resin film 83 at the exit of the transverse stretching machine 50, i.e., the front ends (positive X-axis ends) of RL1 and RL2.

[0033] Although not shown in Figures 1 and 2, the transverse stretcher 50 is equipped with a film heating device that heats the resin film 83 being conveyed along rails RL1 and RL2. Details of the film heating device will be described later. Furthermore, the transverse stretcher 50 also includes film stretchers such as a simultaneous biaxial stretcher that stretches the resin film 83 in the width direction while simultaneously stretching it in the longitudinal direction. For example, the transverse stretcher 50 may be a simultaneous biaxial stretcher without a longitudinal stretcher 40.

[0034] The resin film 83 discharged from the transverse stretching machine 50 is wound up by the winding machine 60. The winding machine 60 is a drive roll driven by a drive source (not shown). The winding machine 60 may include multiple drive rolls driven by a drive source. Furthermore, multiple winding machines 60 may be provided.

[0035] The film thickness sensor FTS is, for example, a non-contact thickness sensor that measures the thickness distribution in the width direction of the resin film 83 being transported after being discharged from the transverse stretching machine 50. In the example shown in Figure 2, the film thickness sensor FTS is positioned between the transverse stretching machine 50 and the winding machine 60 so as to sandwich the resin film 83, which is being transported horizontally, from above and below. Because the film thickness sensor FTS is non-contact, it can scan the resin film 83 in the width direction (Y-axis direction). Therefore, the thickness distribution in the width direction of the resin film 83 can be measured using a compact film thickness sensor FTS. Furthermore, because the resin film 83 is being transported horizontally, the thickness distribution can be measured accurately even when the film thickness sensor FTS is scanned.

[0036] <Configuration and operation of controller 70> The controller 70 controls the extruder 10, T-die 20, casting machine 30, longitudinal stretcher 40, transverse stretcher 50, and winder 60. In other words, the controller 70 controls the entire resin film manufacturing apparatus according to this embodiment to control the production of the resin film 83. The controller 70 is not limited in any way, but may be called a PLC (Programmable Logic Controller), for example. The controller 70 may also be a PC (Personal Computer), for example.

[0037] Although not shown in the diagram, the controller 70 includes, for example, a processing unit such as a CPU (Central Processing Unit) and memory such as RAM (Random Access Memory) and ROM (Read Only Memory) that store various programs and data. In other words, the controller 70 functions as a computer and controls the extruder 10, T-die 20, casting machine 30, longitudinal stretcher 40, transverse stretcher 50, and winding machine 60 based on the above-mentioned programs.

[0038] Therefore, the controller 70 shown in Figure 2 can be composed of the CPU, memory, and other circuits as hardware. Furthermore, the controller 70 can be implemented as software, such as by a program stored in memory. In other words, the controller 70 can be implemented in various forms using hardware, software, or a combination of both.

[0039] Regarding the control of the extruder 10, the controller 70 controls the pressure of the molten resin 82 on the suction side of the gear pump GP, as measured by the pressure sensor PS, to maintain it at a target pressure. Specifically, the controller 70 provides feedback control of the amount of resin raw material 81 supplied from the raw material feeder 14, as well as the rotational speed of the screw 12 and the gear pump GP, based on the pressure of the molten resin 82 measured by the pressure sensor PS.

[0040] In other words, as shown in Figure 2, the controller 70 provides feedback control to the feeder motor FM, screw motor SM, and gear pump GP based on the pressure of the molten resin 82 measured by the pressure sensor PS. By maintaining the pressure of the molten resin 82 on the suction side of the gear pump GP at a target pressure, the amount of molten resin 82 flowing into the T-die 20 can be kept constant.

[0041] As shown in Figure 2, regarding the control of the T-die 20, the controller 70 provides feedback control of the lip spacing of the T-die 20 based on the thickness distribution of the resin film 83 obtained from the film thickness sensor FTS. More specifically, the controller 70 controls the lip spacing of the T-die 20 so that the thickness of the resin film 83 is uniform in the width direction.

[0042] For the control of the casting machine 30, the stretching machine 40, and the winding machine 60, the controller 70 controls the rotational speed of the cast roll CS, the cooling roll CR, the rolls R1 to R5, and the drive source (e.g., a motor not shown) that drives the winding machine 60. For example, the controller 70 controls the rotational speed of the drive source that drives the winding machine 60 so as to maintain a constant tension in the resin film 83 in the winding machine 60.

[0043] Regarding the control of the transverse stretching machine 50, the controller 70 controls the heater of the film heating device that heats the resin film 83 (not shown in Figure 2). Furthermore, the controller 70 may also control the rotational speed of the drive source (e.g., a motor not shown) that drives the clips provided on the rails RL1 and RL2.

[0044] <Detailed configuration of the lateral extension machine 50> Next, the configuration of the transverse stretcher 50 according to this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a schematic side view showing the configuration of the transverse stretcher 50 according to the first embodiment. Figure 4 is a cross-sectional view taken along the line IV-IV in Figure 3.

[0045] As shown in Figures 3 and 4, the transverse stretching machine 50 according to this embodiment is equipped with rails RL1 and RL2, clips CL, and a film heating device 51. As described above, rails RL1 and RL2 and clips CL are conveying devices for transporting the resin film 83. Note that in Figure 4, rails RL1 and RL2 and clips CL are omitted. Furthermore, in the transverse stretching machine 50 shown in Figure 4, multiple film heating devices 51 are arranged side by side adjacent to each other along the transport direction (positive X-axis direction) of the resin film 83.

[0046] <Configuration of the film heating device 51> Now, with reference to Figures 3 to 5, the configuration of the film heating device 51 according to this embodiment will be described. Figure 5 is a partial top view showing the configuration of the film heating device 51. As shown in Figure 3, each film heating device 51 includes a fan FN, a heater HT, a plenum box PB, a temperature sensor TS1, an upper nozzle UN, and a lower nozzle LN. Here, as shown in Figure 3, the controller 70 also constitutes the film heating device 51 and provides feedback control of the heater HT based on the temperature measured by the temperature sensor TS1.

[0047] Fan FN is driven by a drive source such as a motor (not shown) and introduces air into the plenum box PB. Although not particularly limited, the fan FN shown in Figures 3 and 5 is positioned opposite the plenum box PB, and by driving fan FN, air is introduced into the plenum box PB via heater HT.

[0048] The heater HT heats the air contained within the plenum box PB. While not particularly limited, the heater HT shown in Figures 3 and 5 is a pair of box-shaped radiator heaters positioned opposite each other via a fan FN. Furthermore, as shown in Figures 3 and 4, the plenum box PB is a box-shaped member that contains air heated by the heater HT. The side of the plenum box PB facing the fan FN in the positive Y-axis direction is open.

[0049] The pair of heaters HT shown in Figure 5 are positioned opposite each other at both ends of the plenum box PB in the X-axis direction, via fans FN. Therefore, when fans FN are driven, air from outside the plenum box PB is introduced into the plenum box PB from outside, passing through the heaters HT and being heated, as shown by the arrows in Figure 5. Here, the plenum box PB is also heated directly or indirectly by the heaters HT.

[0050] Furthermore, the heater HT is not limited to a radiator heater; any heater that can directly or indirectly heat the air contained in the plenum box PB is acceptable. In other words, air may be introduced into the plenum box PB without going through the heater HT. For example, the heater HT may be installed on the outside of the plenum box PB, and the air contained in the plenum box PB may be indirectly heated by heating the plenum box PB. Alternatively, the heater HT may be installed inside the plenum box PB, and the air contained in the plenum box PB may be heated directly or indirectly.

[0051] The temperature sensor TS1 is a sensor that measures the temperature of heated air, and is, for example, a thermocouple. As shown in Figures 3 and 4, in this embodiment, the temperature sensor TS1 measures the temperature of the air inside the plenum box PB. As described above, the controller 70 provides feedback control to the heater HT based on the temperature measured by the temperature sensor TS1.

[0052] While not particularly limited, the temperature sensor TS1 shown in Figures 3 and 4 is inserted through a through-hole provided on the upper surface of the plenum box PB and measures the temperature of the air in the central part of the plenum box PB. In this way, the temperature sensor TS1 directly measures the temperature of the air inside the plenum box PB, rather than the temperature of the plenum box PB itself.

[0053] The temperature sensor TS1 may be inserted into the central part of the plenum box PB from the open side of the plenum box PB, i.e., from the fan FN side. Alternatively, the temperature sensor TS1 may be inserted through a through hole provided on either the bottom surface or either side in the X-axis direction of the plenum box PB.

[0054] As shown in Figure 3, the upper nozzle UN and the lower nozzle LN extend from the plenum box PB in the width direction (Y-axis direction) of the resin film 83 and are positioned opposite each other via the resin film 83. More specifically, the upper nozzle UN and the lower nozzle LN extend so as to straddle both ends of the resin film 83 in the width direction, i.e., rails RL1 and RL2. Here, as shown in Figure 1, the distance between rails RL1 and RL2 in the Y-axis direction in the transverse stretching machine 50 differs depending on the position in the X-axis direction. Therefore, the Y-axis lengths of the upper nozzle UN and the lower nozzle LN may differ for each film heating device 51.

[0055] On the other hand, as shown in Figure 4, the upper nozzle UN and the lower nozzle LN are rectangular tubular members, and slits extending over substantially the entire length in the Y-axis direction are provided on the lower surface of the upper nozzle UN and the upper surface of the lower nozzle LN. As shown by the thick arrows in Figures 3 and 4, heated air contained in the plenum box PB is sent out from the slits of the upper nozzle UN and the lower nozzle LN toward the resin film 83, thereby heating the resin film 83.

[0056] As shown in Figure 4, multiple pairs of upper nozzles UN and lower nozzles LN may be arranged side by side along the transport direction (positive X-axis direction) of the resin film 83. The number of upper nozzles UN and lower nozzles LN is not limited in any way, but in each film heating device 51 shown in Figure 4, four pairs of upper nozzles UN and lower nozzles LN are arranged side by side along the transport direction of the resin film 83.

[0057] As described above, in the film heating device 51 according to this embodiment, the temperature of the heated air in the plenum box PB is measured by the temperature sensor TS1. Based on the temperature of the air measured by the temperature sensor TS1, the controller 70 provides feedback control to the heater HT. Therefore, in the film heating device 51 according to this embodiment, compared to the case where the heater HT is feedback controlled based on the temperature of the plenum box PB, the temperature of the air sent toward the resin film 83 can be determined more accurately, and the time required to stabilize the quality of the stretched resin film 83 and the amount of resin material used can be reduced.

[0058] (Modified version of the first embodiment) Next, with reference to Figure 6, the configuration of the film heating device 51 according to a modified example of the first embodiment will be described. Figure 6 is a schematic side view showing the configuration of the film heating device 51 according to a modified example of the first embodiment. Figure 6 corresponds to Figure 3.

[0059] In the film heating device 51 shown in Figure 6, the fan FN of the film heating device 51 shown in Figure 3 is divided into an upper fan FN1 and a lower fan FN2. Accordingly, the heater HT is also divided into an upper heater HT1 and a lower heater HT2.

[0060] Here, the air introduced into the plenum box PB via the upper heater HT1 by driving the upper fan FN1 is mainly delivered towards the resin film 83 from the upper nozzle UN. On the other hand, the air introduced into the plenum box PB via the lower heater HT2 by driving the lower fan FN2 is mainly delivered towards the resin film 83 from the lower nozzle LN.

[0061] Therefore, the film heating device 51 shown in Figure 6 is provided with an upper temperature sensor TS11 for measuring the temperature of the air in the upper central part of the plenum box PB, and a lower temperature sensor TS12 for measuring the temperature of the air in the lower central part of the plenum box PB. Although not particularly limited, in the film heating device 51 shown in Figure 6, the upper temperature sensor TS11 is inserted through a through hole provided on the upper surface of the plenum box PB. The lower temperature sensor TS12 is inserted through a through hole provided on the lower surface of the plenum box PB. The temperature sensors TS11 and TS12 may be inserted into the central part of the plenum box PB from the open side of the plenum box PB, i.e., from the fan FN side.

[0062] As shown in Figure 6, the controller 70 provides feedback control to the upper heater HT1 based on the temperature measured by the upper temperature sensor TS11. The controller 70 also provides feedback control to the lower heater HT2 based on the temperature measured by the lower temperature sensor TS12. The other components are the same as those in the first embodiment shown in Figures 3 and 4, so their explanation will be omitted.

[0063] (Second embodiment) Next, a film heating device 51 according to the second embodiment will be described. The configuration of the film heating device 51 according to the second embodiment is the same as that of the film heating device 51 according to the first embodiment shown in Figures 3 and 4, so the description will be omitted. The internal configuration of the controller 70 of the film heating device 51 according to this embodiment differs from that of the film heating device 51 according to the first embodiment.

[0064] <Configuration of the controller 70 according to the second embodiment> Referring to Figure 7, the configuration of the controller 70 according to the second embodiment will be described in detail. Figure 7 is a block diagram showing the configuration of the controller 70 according to the second embodiment. As shown in Figure 7, the controller 70 according to this embodiment includes a state observation unit 71, a control condition learning unit 72, a storage unit 73, and a control signal output unit 74.

[0065] The controller 70 according to this embodiment, like the controller 70 according to the first embodiment, provides feedback control of the heater HT based on the air temperature measured by the temperature sensor TS1, and also learns the control conditions for the heater HT.

[0066] Each functional block constituting the controller 70 can be comprised of a CPU, memory, and other circuits in hardware terms, and can be implemented in software terms by programs loaded into memory. Therefore, each functional block can be implemented in various forms depending on the computer's hardware, software, or combinations thereof.

[0067] The state observation unit 71 calculates the control deviation of the heater HT from the measured temperature pv obtained from the temperature sensor TS1. The control deviation is the difference between the target value and the measured temperature pv. Here, the target value is the target temperature (set temperature) set for the heater HT. On the other hand, the measured temperature pv is the measured temperature obtained from the temperature sensor TS1.

[0068] Then, the state observation unit 71 determines the current state st and the reward rw for the previously selected action ac for the heater HT, based on the calculated control deviation. The state st is pre-set to divide the infinitely possible control deviation values ​​into a finite number of values. As a simple example for explanation, if the control deviation is err, then -4.0℃≦err<-3.0℃ is set as state st1, -3.0℃≦err<-2.0℃ as state st2, -2.0℃≦err<-1.0℃ as state st3, -1.0℃≦err<1.0℃ as state st4, 1.0℃≦err≦2.0℃ as state st5, 2.0℃≦err≦3.0℃ as state st6, 3.0℃≦err≦4.0℃ as state st7, 4.0℃≦err≦5.0℃ as state st8, and so on. In practice, many more subdivided states st are often set.

[0069] Reward rw is an index used to evaluate the action ac chosen in the previous state st. Specifically, if the absolute value of the current control deviation calculated is smaller than the absolute value of the previous control deviation, the state observation unit 71 determines that the previously selected action ac is appropriate, and sets the reward rw to a positive value, for example. In other words, the reward rw is determined in such a way that the previously selected action ac is more likely to be selected again in the same state st as before.

[0070] Conversely, if the absolute value of the current control deviation calculated is greater than the absolute value of the previous control deviation, the state observation unit 71 determines that the previously selected action ac is inappropriate and, for example, sets the reward rw to a negative value. In other words, the reward rw is determined in such a way that the previously selected action ac is less likely to be selected again in the same state st as before. Specific examples of reward rw will be discussed later. Furthermore, the value of reward rw can be determined as appropriate. For example, the value of reward rw may always be positive, or it may always be negative.

[0071] The control condition learning unit 72 performs reinforcement learning on the heater HT. Specifically, the control condition learning unit 72 updates the control conditions (learning results) based on the reward rw, and selects the optimal action ac corresponding to the current state st from the updated control conditions. The control conditions are a combination of state st and action ac. Table 1 shows simplified control conditions (learning results) corresponding to the states st1 to st8 described above. In the example in Figure 3, the control condition learning unit 72 stores the updated control conditions cc in, for example, the memory unit 73, and reads and updates the control conditions cc from the memory unit 73.

[0072] Table 1 shows the control conditions (learning results) obtained by Q-learning, an example of reinforcement learning. The top row of Table 1 shows the eight states st1 to st8 mentioned above. That is, each of the columns from 2 to 9 represents the eight states st1 to st8. On the other hand, the leftmost column of Table 1 shows the five actions ac1 to ac5. That is, each of the rows from columns 2 to 6 represents the five actions ac1 to ac5.

[0073] In the example in Table 1, action ac1 (output change: -1%) is set to reduce the output to heater HT (e.g., voltage) by 1.0%. Action ac2 (output change: -0.5%) is set to reduce the output to heater HT by 0.5%. Action ac3 (output change: 0%) is set to maintain the output to heater HT. Action ac4 (output change: +0.5%) is set to increase the output to heater HT by 0.5%. Action ac5 (output change: +1.0%) is set to increase the output to heater HT by 1.0%. The example in Table 1 is merely a simplified example for illustrative purposes; in reality, many more subdivided actions ac are often set.

[0074] In Table 1, the value determined by the combination of state st and action ac is called value Q(st, ac). Value Q is updated sequentially based on reward rw using a known update formula after an initial value is given. The initial value of value Q is included in the learning conditions shown in Figure 3, for example. The learning conditions are input by the operator, for example. The initial value of value Q may be stored in the memory unit 73, or past learning results may be used as the initial value. The learning conditions shown in Figure 3 also include, for example, states st1 to st8 and actions ac1 to ac5 shown in Table 1.

[0075] [Table 1]

[0076] The value Q will be explained using state st7 in Table 1 as an example. In state st7, the control deviation is between 3.0°C and 4.0°C, so the heating temperature by heater HT is too high. Therefore, it is necessary to reduce the output of heater HT. Accordingly, as a result of learning by the control condition learning unit 72, the value Q of actions ac1 and ac2, which reduce the output to heater HT, is large. On the other hand, the value Q of actions ac4 and ac5, which increase the output to heater HT, is small.

[0077] In the example in Table 1, for example, if the control deviation is 3.5°C, the state st is state st7. Therefore, the control condition learning unit 72 selects the optimal action ac2 in state st7, where the value Q is maximized, and outputs it to the control signal output unit 74. The control signal output unit 74 reduces the control signal ctr output to the heater HT by 0.5% based on the input action ac2. The control signal ctr is, for example, a voltage signal.

[0078] Then, if the absolute value of the next control deviation is smaller than the absolute value of the current control deviation of 3.5°C, the state observation unit 71 determines that the selection of action ac2 in the current state st7 is appropriate and outputs a positive reward rw. Therefore, the control condition learning unit 72 updates the control conditions to increase the value of action ac2 in state st7, +3.6, according to the reward rw. As a result, in the case of state st7, the control condition learning unit 72 continues to select action ac2.

[0079] On the other hand, if the absolute value of the next control deviation is greater than the absolute value of the current control deviation of 3.5°C, the state observation unit 71 determines that the selection of action ac2 in the current state st7 is inappropriate and outputs a negative reward rw. Therefore, the control condition learning unit 72 updates the control conditions so that the value of action ac2 in state st7, +3.6, is reduced according to the reward rw. As a result, if the value of action ac2 in state st7 becomes less than the value of action ac1, +2.6, then in the case of state st7, the control condition learning unit 72 selects action ac1 instead of action ac2.

[0080] The timing for updating the control conditions is not limited to the next update; it can be determined as appropriate, taking into account time lags and other factors. Furthermore, in the initial stages of learning, actions 'ac' may be selected randomly to facilitate learning. While Table 1 describes reinforcement learning using a simple Q-learning method, there are various learning algorithms, including Q-learning, AC (Actor-Critic) method, TD learning, and Monte Carlo method, and the algorithm is not limited to these. For example, if the number of states 'st' and actions 'ac' increases and a combinatorial explosion occurs, the AC method or similar algorithm may be used, depending on the situation.

[0081] Furthermore, in AC methods, a probability distribution function is often used as the policy function. This probability distribution function is not limited to the normal distribution function; for example, the sigmoid function or the softmax function may be used for the purpose of simplification. The sigmoid function is the most commonly used function in neural networks. Since reinforcement learning is a type of machine learning, just like neural networks, the sigmoid function can be adopted. In addition, the sigmoid function has the advantage of being simple and easy to handle. As explained above, there are various learning algorithms and functions that can be used, but you should select the one that is best suited to the process as appropriate.

[0082] As explained above, the film heating apparatus 51 according to the second embodiment does not use PID control in the first place, so there is no need to adjust the PID control parameters when the process conditions are changed. In addition, the controller 70 updates the control conditions (learning results) based on the reward rw through reinforcement learning, and selects the optimal action ac corresponding to the current state st from the updated control conditions. Therefore, even when the process conditions are changed, the time required for adjustment and the amount of resin material can be reduced compared to the first embodiment.

[0083] <Film heating control method> Next, with reference to Figure 8, the details of the film heating control method according to the second embodiment will be described. Figure 8 is a flowchart of the film heating control method according to the second embodiment. In describing Figure 8, Figure 7 will also be referred to as appropriate.

[0084] First, as shown in Figure 8, the state observation unit 71 of the controller 70 shown in Figure 7 calculates the control deviation for the heater HT from the temperature measured by the temperature sensor TS1. Then, based on the calculated control deviation, the current state st and the reward rw for the previously selected action ac are determined (step S1). Note that at the start of control, there is no previously selected action ac (for example, last time), and therefore the reward rw cannot be determined, so only the current state st, i.e., the state at the start of control, is determined.

[0085] Next, as shown in Figure 8, the control condition learning unit 72 of the controller 70 updates the control conditions, which are combinations of state st and action ac, based on the reward rw. Then, it selects the optimal action ac corresponding to the current state st from the updated control conditions (step S2). Note that at the start of control, the control conditions are not updated and remain at their initial values, but the optimal action ac corresponding to the state st at the start of control is selected. Then, as shown in Figure 8, the control signal output unit 74 of the controller 70 outputs a control signal ctr to the heater HT based on the optimal action ac selected by the control condition learning unit 72 (step S3).

[0086] If the production of the resin film is not yet complete (step S4NO), the control process returns to step S1 and continues. On the other hand, if the production of the resin film is complete (step S4YES), the control process ends. In other words, steps S1 to S3 are repeated until the production of the resin film is complete. The other components are the same as in the first embodiment, so their description will be omitted.

[0087] (Modified version of the second embodiment) Next, with reference to Figure 9, a modified version of the film heating device 51 according to the second embodiment will be described. The configuration of the modified version of the film heating device 51 according to the second embodiment is the same as the configuration of the film heating device 51 according to the first embodiment shown in Figures 3 and 4, so the description will be omitted. The configuration of the controller 70 in the modified version of the second embodiment of the film heating device 51 differs from that of the film heating device 51 according to the second embodiment.

[0088] Figure 9 is a block diagram showing the configuration of a modified controller 70 according to the second embodiment. As shown in Figure 9, the modified controller 70 according to the second embodiment includes a state observation unit 71, a control condition learning unit 72, a storage unit 73, and a PID controller 74a. That is, the modified controller 70 according to the second embodiment includes a PID controller 74a as the control signal output unit 74 in the controller 70 according to the second embodiment shown in Figure 7. The PID controller 74a is also a form of control signal output unit.

[0089] The state observation unit 71, similar to the second embodiment, determines the current state st and the reward rw for the previously selected action ac for the heater HT based on the calculated control deviation err. The state observation unit 71 then outputs the current state st and the reward rw to the control condition learning unit 72. Furthermore, the state observation unit 71 according to the modified version of the second embodiment outputs the calculated control deviation err to the PID controller 74a.

[0090] The control condition learning unit 72 also performs reinforcement learning on the heater HT, similar to the second embodiment. Specifically, the control condition learning unit 72 updates the control conditions (learning results) based on the reward rw, and selects the optimal action ac corresponding to the current state st from the updated control conditions. In the second embodiment, the action ac selected by the control condition learning unit 72 directly modifies the output to the heater HT. In contrast, in a modified version of the second embodiment, the action ac selected by the control condition learning unit 72 modifies the parameters of the PID controller 74a.

[0091] As shown in Figure 9, the parameters of the PID controller 74a are sequentially changed based on the action ac output from the control condition learning unit 72. On the other hand, the PID controller 74a outputs a control signal ctr to the heater HT based on the input control deviation err. The control signal ctr is, for example, a voltage signal. The other components are the same as those in the second embodiment, so their description will be omitted.

[0092] As explained above, the film heating device 51 according to the modified version of the second embodiment uses PID control, and therefore parameter adjustment is required when process conditions are changed. In the film heating device 51 according to the modified version of the second embodiment, the controller 70 updates the control conditions (learning results) based on the reward rw through reinforcement learning, and selects the optimal action ac corresponding to the current state st from the updated control conditions. Here, action ac in reinforcement learning is a change in the parameters of the PID controller 74a. Therefore, even when process conditions are changed, the time required for parameter adjustment and the amount of resin material used can be reduced compared to the second embodiment.

[0093] (Third embodiment) Next, the configuration of the film heating device 51 according to the third embodiment will be described with reference to Figures 10 and 11. Figure 10 is a schematic side view showing the configuration of the film heating device 51 according to the third embodiment. Figure 11 is a cross-sectional view taken along the line XI-XI in Figure 10. Figure 10 corresponds to Figure 3, and Figure 11 corresponds to Figure 4.

[0094] In the film heating device 51 shown in Figures 3 and 4, the temperature of the air inside the plenum box PB is measured by the temperature sensor TS1. In contrast, in the film heating device 51 shown in Figures 10 and 11, the temperature of the air discharged from the upper nozzle UN and the lower nozzle LN is measured by the upper temperature sensor TS21 and the lower temperature sensor TS22, respectively.

[0095] Although not particularly limited, the upper temperature sensor TS21 measures the temperature of the air discharged from the upper nozzle UN at the center of the upper nozzle UN in the longitudinal direction (Y-axis direction) and the center of the plenum box PB in the width direction (X-axis direction), as shown in Figures 10 and 11. Here, as shown in Figure 11, the upper temperature sensor TS21 is installed between the second upper nozzle UN and the third upper nozzle UN from the negative X-axis side, among the four upper nozzles UN arranged in parallel in the X-axis direction. The upper temperature sensor TS21 may be installed to measure the temperature of the air directly below the slit of the upper nozzle UN. Alternatively, the upper temperature sensor TS21 may be installed to measure the temperature of the air directly above the slit inside the upper nozzle UN.

[0096] Furthermore, although not particularly limited, the lower temperature sensor TS22 measures the temperature of the air discharged from the lower nozzle LN at the center of the lower nozzle LN in the longitudinal direction (Y-axis direction) and the center of the plenum box PB in the width direction (X-axis direction), as shown in Figures 10 and 11. Here, as shown in Figure 11, the lower temperature sensor TS22 is installed between the second and third lower nozzle LN from the negative X-axis side, among the four lower nozzles LN arranged in parallel in the X-axis direction. The lower temperature sensor TS22 may be installed to measure the temperature of the air directly above the slit of the lower nozzle LN. Alternatively, the lower temperature sensor TS22 may be installed to measure the temperature of the air directly below the slit inside the lower nozzle LN.

[0097] Then, as shown in Figure 10, the controller 70 provides feedback control to the heater HT based on the temperatures measured by the upper temperature sensor TS21 and the lower temperature sensor TS22. For example, the controller 70 provides feedback control to the heater HT based on the average value of the temperatures measured by the upper temperature sensor TS21 and the lower temperature sensor TS22.

[0098] In the film heating device 51 according to this embodiment, the temperature of the air discharged from the upper nozzle UN and the lower nozzle LN is measured by the upper temperature sensor TS21 and the lower temperature sensor TS22, respectively. Based on the air temperatures measured by the upper temperature sensor TS21 and the lower temperature sensor TS22, the controller 70 provides feedback control to the heater HT.

[0099] Therefore, the film heating device 51 according to this embodiment can more accurately determine the temperature of the air sent toward the resin film 83 compared to the film heating device 51 according to the first embodiment, which measures the temperature of the air inside the plenum box PB. As a result, the time required to stabilize the quality of the stretched resin film 83 and the amount of resin material used can be further reduced. The other components are the same as those in the first embodiment shown in Figures 3 and 4, so their explanation will be omitted.

[0100] (Modification 1 of the third embodiment) Next, with reference to Figure 12, the configuration of the film heating device 51 according to Modification 1 of the third embodiment will be described. Figure 12 is a schematic side view showing the configuration of the film heating device 51 according to Modification 1 of the third embodiment. Figure 12 corresponds to Figure 10.

[0101] In the film heating device 51 shown in Figure 12, the fan FN of the film heating device 51 shown in Figure 10 is divided into an upper fan FN1 and a lower fan FN2. Accordingly, the heater HT is also divided into an upper heater HT1 and a lower heater HT2.

[0102] Here, the air introduced into the plenum box PB via the upper heater HT1 by driving the upper fan FN1 is mainly delivered towards the resin film 83 from the upper nozzle UN. On the other hand, the air introduced into the plenum box PB via the lower heater HT2 by driving the lower fan FN2 is mainly delivered towards the resin film 83 from the lower nozzle LN.

[0103] Therefore, as shown in Figure 12, the controller 70 provides feedback control to the upper heater HT1 based on the temperature of the air delivered from the upper nozzle UN and measured by the upper temperature sensor TS21. The controller 70 also provides feedback control to the lower heater HT2 based on the temperature of the air delivered from the lower nozzle LN and measured by the lower temperature sensor TS22. The other components are the same as those of the third embodiment shown in Figures 10 and 11, so their description will be omitted.

[0104] (Modification 2 of the third embodiment) Next, with reference to Figure 13, the configuration of the film heating device 51 according to the second modification of the third embodiment will be described. Figure 13 is a schematic side view showing the configuration of the film heating device 51 according to the second modification of the third embodiment. Figure 13 corresponds to Figure 12.

[0105] In the film heating device 51 shown in Figure 13, three upper temperature sensors TS21a, TS21b, and TS21c are arranged side by side along the longitudinal direction (Y-axis direction) of the upper nozzle UN. More specifically, upper temperature sensor TS21a measures the temperature of the air discharged from the upper nozzle UN at the positive Y-axis end of the resin film 83. Upper temperature sensor TS21b measures the temperature of the air discharged from the upper nozzle UN at the Y-axis center of the resin film 83. Upper temperature sensor TS21c measures the temperature of the air discharged from the upper nozzle UN at the negative Y-axis end of the resin film 83.

[0106] Furthermore, in the film heating device 51 shown in Figure 13, three lower temperature sensors TS22a, TS22b, and TS22c are arranged in parallel along the longitudinal direction (Y-axis direction) of the lower nozzle LN. More specifically, the lower temperature sensor TS22a measures the temperature of the air discharged from the lower nozzle LN at the positive Y-axis end of the resin film 83. The lower temperature sensor TS22b measures the temperature of the air discharged from the lower nozzle LN at the Y-axis center of the resin film 83. The lower temperature sensor TS22c measures the temperature of the air discharged from the lower nozzle LN at the negative Y-axis end of the resin film 83.

[0107] Then, as shown in Figure 13, the controller 70 provides feedback control to the upper heater HT1 based on the temperatures measured by the upper temperature sensors TS21a, TS21b, and TS21c. For example, the controller 70 provides feedback control to the upper heater HT1 based on the average value of the temperatures measured by the upper temperature sensors TS21a, TS21b, and TS21c.

[0108] Furthermore, as shown in Figure 13, the controller 70 provides feedback control to the lower heater HT2 based on the temperatures measured by the lower temperature sensors TS22a, TS22b, and TS22c. For example, the controller 70 provides feedback control to the lower heater HT2 based on the average value of the temperatures measured by the lower temperature sensors TS22a, TS22b, and TS22c.

[0109] The other configurations are the same as in the modified example 1 of the third embodiment shown in Figure 12, so their description will be omitted. Furthermore, the third embodiment and the second embodiment may be combined.

[0110] (Fourth embodiment) <Configuration of the film heating device 51> Next, with reference to Figure 14, a film heating device 51 according to the fourth embodiment will be described. Figure 14 is a schematic side view showing the configuration of the film heating device 51 according to the fourth embodiment. As shown in Figure 14, the film heating device 51 according to this embodiment further includes the upper temperature sensor TS11 and the lower temperature sensor TS12 shown in Figure 6, in addition to the film heating device 51 shown in Figure 13.

[0111] In other words, the film heating device 51 according to this embodiment has a configuration that combines the film heating device 51 according to a modified example of the first embodiment shown in Figure 6 and the film heating device 51 according to a modified example 2 of the third embodiment shown in Figure 13. Furthermore, in the film heating device 51 according to this embodiment, the controller 70 is configured to be switchable between a first control mode and a second control mode.

[0112] In the first control mode, the upper heater HT1 and the lower heater HT2 are controlled based on the air temperature measured by the upper temperature sensor TS11 and the lower temperature sensor TS12, which are the first temperature sensors, similar to the film heating device 51 shown in Figure 6. Here, as shown in Figure 14, the upper temperature sensor TS11 measures the temperature of the air in the upper central part of the plenum box PB, and the lower temperature sensor TS12 measures the temperature of the air in the lower central part of the plenum box PB.

[0113] On the other hand, in the second control mode, the upper heater HT1 and the lower heater HT2 are controlled in the same manner as the film heating device 51 shown in Figure 13. Specifically, the upper heater HT1 is controlled based on the air temperature measured by the upper temperature sensors TS21a, TS21b, and TS21c, which are second temperature sensors. At the same time, the lower heater HT2 is controlled based on the air temperature measured by the lower temperature sensors TS22a, TS22b, and TS22c, which are second temperature sensors.

[0114] While not particularly limited, for example, when starting up the resin film manufacturing apparatus shown in Figures 1 and 2, the controller 70 executes a first control mode until the resin film 83 is supplied to the transverse stretcher 50, i.e., the film heating device 51. After the resin film 83 is supplied to the film heating device 51, the controller 70 executes a second control mode. In this embodiment, the film heating device 51 can utilize both the first and second control modes, but only one of them may be used.

[0115] The other components are the same as in the modified example 2 of the third embodiment shown in Figure 13, so their description will be omitted. Furthermore, the fourth embodiment is not limited to a combination of the modified version of the first embodiment shown in Figure 6 and modified version 2 of the third embodiment shown in Figure 13, but may be any combination of the first embodiment (including the modified version) and the third embodiment (including modified versions 1 and 2). Alternatively, the fourth embodiment may be combined with the second embodiment.

[0116] <Film heating control method> Next, with reference to Figures 15 to 17, the details of the film heating control method using the film heating device 51 according to the fourth embodiment will be described. Figure 15 is a flowchart of the film heating control method according to the fourth embodiment. Figure 16 is a schematic side view of the film heating device 51 in the first control mode. Figure 17 is a schematic side view of the film heating device 51 in the second control mode. In describing Figure 15, Figures 16 and 17 will be referred to as appropriate.

[0117] First, as shown in Figure 15, after the resin film manufacturing apparatus is started, the first control mode is initiated (step S11). As shown in Figure 16, in the first control mode, the controller 70 provides feedback control to the upper heater HT1 and the lower heater HT2, respectively, based on the air temperature measured by the upper temperature sensor TS11 and the lower temperature sensor TS12.

[0118] Next, when the supply of resin film 83 to the film heating device 51 begins (YES in step S12), the control switches from the first control mode to the second control mode. That is, the second control mode is started, and the production of resin film, i.e., the product, begins (step S13). As shown in Figure 17, in the second control mode, the controller 70 provides feedback control to the upper heater HT1 and the lower heater HT2, respectively, based on the air temperature measured by the upper temperature sensors TS21a, TS21b, TS21c and the lower temperature sensors TS22a, TS22b, TS22c. On the other hand, if the supply of resin film 83 to the film heating device 51 has not been started (NO in step S12), the first control mode is continued as is.

[0119] Next, once the product manufacturing is complete (YES in step S14), the second control mode is terminated. On the other hand, if the product manufacturing is not complete (NO in step S14), the second control mode is continued.

[0120] (Modification of the fourth embodiment) Next, with reference to Figure 18, a modified film heating device 51 according to the fourth embodiment will be described. The configuration of the modified film heating device 51 according to the fourth embodiment is the same as that of the film heating device 51 according to the fourth embodiment shown in Figure 14, so a description will be omitted.

[0121] As shown in Figure 18, in the modified film heating device 51, in the second control mode, the controller 70 performs cascade control using the air temperature measured by the upper temperature sensors TS21a, TS21b, TS21c and the lower temperature sensors TS22a, TS22b, TS22c, as well as the air temperature measured by the upper temperature sensor TS11 and the lower temperature sensor TS12.

[0122] More specifically, first, the controller 70 determines the set temperatures of the upper heater HT1 and the lower heater HT2 based on the air temperature measured by the upper temperature sensors TS21a, TS21b, TS21c and the lower temperature sensors TS22a, TS22b, TS22c.

[0123] For example, the controller 70 determines the set temperature (target temperature) of the upper heater HT1 based on the deviation between the target air temperature near the resin film 83 and the average value of the air temperature measured by the upper temperature sensors TS21a, TS21b, and TS21c. The controller 70 also determines the set temperature (target temperature) of the lower heater HT2 based on the deviation between the target air temperature near the resin film 83 and the average value of the air temperature measured by the lower temperature sensors TS22a, TS22b, and TS22c.

[0124] Next, the controller 70 provides feedback control to the upper heater HT1 and the lower heater HT2 based on the determined set temperature and the air temperature measured by the upper temperature sensor TS11 and the lower temperature sensor TS12.

[0125] For example, the controller 70 provides feedback control to the upper heater HT1 based on the deviation between the determined set temperature of the upper heater HT1 and the air temperature measured by the upper temperature sensor TS11. The controller 70 also provides feedback control to the lower heater HT2 based on the deviation between the determined set temperature of the lower heater HT2 and the air temperature measured by the lower temperature sensor TS12.

[0126] In the film heating device 51 according to a modified example of the fourth embodiment, the temperature of the air supplied to the resin film 83 can be controlled more precisely by the cascade control described above compared to the film heating device 51 according to the fourth embodiment. As a result, the time required to stabilize the quality of the stretched resin film 83 and the amount of resin material used can be further reduced. The other components are the same as those of the fourth embodiment, so their description will be omitted. Furthermore, a modified version of the fourth embodiment may be combined with the second embodiment.

[0127] The present invention has been described in detail above based on embodiments, but it goes without saying that the present invention is not limited to the embodiments already described, and various modifications are possible without departing from the spirit of the invention. [Explanation of symbols]

[0128] 10 Extruder 11 cylinders 12 Screw 13 Hoppa 14. Raw material feeder 20 T-die 30 Casting Machines 40 Longitudinal stretcher 50 Lateral stretching machine 51 Film heating device 60 Winder 70 Controllers 71 State Observation Unit 72 Control Condition Learning Unit 73 Memory section 74 Control signal output unit, 74a PID controller 81 Resin raw materials 82 Molten resin, 82a Film-like molten resin 83 Resin film CR Cooling Roll CL Clip CS Cast Roll FH Feeder Hopper FM feeder motor FN fan, FN1 upper fan, FN2 lower fan FS feeder screw FTS Film Thickness Sensor GP Gear Pump HT heater, HT1 upper heater, HT2 lower heater LN Lower Nozzle PB Plenum Box PS pressure sensor R1~R5 Roll RL1, RL2 rails SM Screw Motor TS1 temperature sensor, TS11 upper temperature sensor, TS12 lower temperature sensor TS21, TS21a, TS21b, TS21c Upper Temperature Sensor TS22, TS22a, TS22b, TS22c Lower Temperature Sensor UN Upper Nozzle

Claims

1. A film heating device for heating a resin film being transported, A plenum box that contains air, A heater for heating the air contained in the plenum box, The plenum box extends in the width direction of the resin film and is arranged opposite to each other via the resin film, and comprises at least one pair of nozzles that deliver the air contained in the plenum box toward the resin film, A temperature sensor for measuring the temperature of the heated air, A controller that provides feedback control of the heater based on the temperature measured by the temperature sensor, is provided. Film heating device.

2. The temperature sensor measures the temperature of the air inside the plenum box. The film heating apparatus according to claim 1.

3. The temperature sensor measures the temperature of at least one of the air in the pair of nozzles or the air discharged from the pair of nozzles. The film heating apparatus according to claim 1.

4. The aforementioned temperature sensor is A first temperature sensor for measuring the temperature of the air inside the plenum box, Includes a second temperature sensor for measuring the temperature of at least one of the air in the pair of nozzles or the air discharged from the pair of nozzles, The aforementioned controller, A first control mode that provides feedback control of the heater based on the air temperature measured by the first temperature sensor, The system is configured to be switchable between a second control mode, which provides feedback control of the heater based on the air temperature measured by the second temperature sensor, and a second control mode, which provides feedback control of the heater based on the air temperature measured by the second temperature sensor. The film heating apparatus according to claim 1.

5. In the second control mode described above, The set temperature of the heater is determined based on the air temperature measured by the second temperature sensor. Based on the set temperature and the air temperature measured by the first temperature sensor, the output of the heater is determined. The film heating apparatus according to claim 4.

6. When the film heating device is started, The controller executes the first control mode, and then executes the second control mode. The film heating apparatus according to claim 4 or 5.

7. The aforementioned heater is An upper heater for heating the upper part of the plenum box, The system includes a lower heater for heating the lower part of the plenum box, The first temperature sensor is An upper temperature sensor for measuring the temperature of the air at the top of the plenum box, The system includes a lower temperature sensor for measuring the temperature of the air at the bottom of the plenum box, The second temperature sensor is An upper temperature sensor that measures the temperature of at least one of the pair of nozzles, which is connected to the upper part of the plenum box, the air inside the nozzle or the air discharged from the nozzle, The system includes a lower temperature sensor that measures the temperature of at least one of the pair of nozzles, either the air in the nozzle connected to the lower part of the plenum box or the air discharged from that nozzle, The aforementioned controller, In the first control mode, the upper heater is feedback controlled based on the air temperature measured by the upper temperature sensor of the first temperature sensor, and the lower heater is feedback controlled based on the air temperature measured by the lower temperature sensor of the first temperature sensor. In the second control mode, the upper heater is feedback controlled based on the air temperature measured by the upper temperature sensor of the second temperature sensor, and the lower heater is feedback controlled based on the air temperature measured by the lower temperature sensor of the second temperature sensor. The film heating apparatus according to claim 4.

8. The second temperature sensor is arranged in parallel in multiple locations along the width direction of the resin film. The film heating apparatus according to claim 4.

9. A conveying device for transporting resin film, A film stretcher comprising a film heating device for heating the resin film being transported by the transport device, and stretching the resin film while transporting it, The aforementioned film heating device is A plenum box that contains air, A heater for heating the air contained in the plenum box, The plenum box extends in the width direction of the resin film and is arranged opposite to each other via the resin film, and comprises at least one pair of nozzles that deliver the air contained in the plenum box toward the resin film, A temperature sensor for measuring the temperature of the heated air, A controller that provides feedback control of the heater based on the temperature measured by the temperature sensor, is provided. Film stretcher.

10. An extruder that melts and extrudes the raw resin material that is fed in, A die connected to the extruder for forming molten resin into a film, A casting machine including a cast roll that cools the film-like molten resin extruded from the die and discharges the solidified resin film, A film manufacturing apparatus comprising a film stretcher that stretches the resin film while conveying it, The film stretcher is equipped with a film heating device for heating the resin film being conveyed. The aforementioned film heating device is A plenum box that contains air, A heater for heating the air contained in the plenum box, The plenum box extends in the width direction of the resin film and is arranged opposite to each other via the resin film, and comprises at least one pair of nozzles that deliver the air contained in the plenum box toward the resin film, A temperature sensor for measuring the temperature of the heated air, A controller that provides feedback control of the heater based on the temperature measured by the temperature sensor, is provided. Film manufacturing equipment.

11. A film heating control method for controlling the heating of a conveyed resin film by a film heating device, The aforementioned film heating device is A plenum box that contains air, A heater for heating the air contained in the plenum box, The plenum box extends in the width direction of the resin film and is arranged opposite to each other via the resin film, and comprises at least one pair of nozzles that deliver the air contained in the plenum box toward the resin film, It comprises a temperature sensor for measuring the temperature of the heated air, Computers (a) A step of feedback controlling the heater based on the temperature measured by the temperature sensor, Film heating control method.

Images