JP2020168862A - Film molding apparatus - Google Patents

Abstract

To provide a film molding apparatus capable of forming film rolls with a relatively fewer small-size bumps and dents.SOLUTION: The film molding apparatus includes: a die device which extrudes a molten resin in a tube-like form to mold a film; a measurement part which measures a thickness profile of the film in a circumferential direction; a plurality of adjustment parts for changing the thickness profile of the film; and a control device 7 which controls the plurality of adjustment parts so that the thickness profile becomes closer to a target thickness profile. The control device 7 changes the target thickness profile based on the measured thickness profile.SELECTED DRAWING: Figure 4

Description

The present invention relates to a film molding apparatus.

A film forming apparatus is known in which a molten resin extruded into a tube shape from an annular discharge port of a die apparatus is solidified to form a film. Conventionally, a film forming apparatus has been proposed in which the variation in film thickness is reduced by changing the radial width of the annular discharge port (Patent Document 1).

JP-A-6-99472

According to the conventional film molding apparatus described in Patent Document 1, the variation in film thickness can be reduced to some extent, and the accuracy as a film can be satisfied. However, since the variation in film thickness remains to some extent, if the variation accumulates when the film is wound to form a film roll body, a large hump or dent can occur.

The present invention has been made in view of these circumstances, and an object of the present invention is to provide a film forming apparatus capable of forming a film roll body having relatively few humps and dents or a small dent.

In order to solve the above problems, the film forming apparatus of the present invention includes a die apparatus for extruding a molten resin into a tube shape to form a film, a measuring unit for measuring a film thickness profile in a predetermined direction, and a film. It is provided with an adjusting means for changing the thickness profile of the above, and a control device for controlling the adjusting means so that the thickness profile approaches the target thickness profile. The control device changes the target thickness profile based on the measured thickness profile.

Another aspect of the present invention is also a film forming apparatus. This device includes a die device that extrudes molten resin into a tube to form a film, a measuring unit that measures the film thickness at each position in a predetermined direction, and an adjusting means for changing the film thickness at each position. A control device for controlling the adjusting means so that the film thickness at the position approaches the reference film thickness is provided. The control device controls the adjusting means so that the film thickness is temporarily thinner than the reference film thickness at an arbitrary timing with respect to the portion of the film thicker than the reference film thickness, and the control device controls the adjusting means of the film thinner than the reference film thickness. The adjusting means is controlled so that the film thickness temporarily becomes thicker than the reference film thickness with respect to the portion at an arbitrary timing.

It should be noted that any combination of the above components and those in which the components and expressions of the present invention are mutually replaced between methods, devices, systems and the like are also effective as aspects of the present invention.

According to the present invention, it is possible to form a film having a small variation in thickness and uniform physical properties.

It is a figure which shows the schematic structure of the film forming apparatus which concerns on 1st Embodiment. It is sectional drawing which shows the die apparatus and cooling apparatus of FIG. 1 and the periphery thereof. It is a top view which shows the die apparatus of FIG. It is a block diagram which shows typically the function and structure of the control device of FIG. FIG. 5A is a diagram schematically showing an example of a profile held in the profile holding portion, and FIG. 5B is a diagram schematically showing a target thickness profile held in the target profile holding portion. Is. It is a flowchart which shows the process of a film forming apparatus. FIG. 7A is a diagram schematically showing an example of a profile held in the profile holding portion of the film forming apparatus according to the second embodiment, and FIG. 7B is a diagram schematically showing an example of the profile held in the profile holding portion of the film forming apparatus. It is a figure which shows typically the target thickness profile to be held.

Hereinafter, the same or equivalent components and members shown in the drawings shall be designated by the same reference numerals, and redundant description will be omitted as appropriate. In addition, the dimensions of the members in each drawing are shown enlarged or reduced as appropriate for easy understanding. In addition, some of the members that are not important for explaining the embodiment in each drawing are omitted and displayed.

The process leading to obtaining the film molding apparatus according to the embodiment will be described.
The film formed by the film forming apparatus usually has some variation in film thickness. Even if this variation satisfies the accuracy of the film, when the film is wound by a winder to form a film roll, if the variation is accumulated, more specifically, the thick portions of the film are formed. Alternatively, when thin parts are stacked on top of each other, humps and dents are formed on the film roll body. The humps and dents on the film roll cause distortion of the film.

Conventionally, the position of the molten resin extruded from the die device in the circumferential direction and the position of the films to be stacked when the film is wound are relatively gradually shifted, in other words, the film is twisted to form a film roll. It prevented the formation of humps and dents. Specifically, the film was twisted by the following methods 1 to 4 to prevent humps and dents from being formed on the film roll body.
1. 1. Twist the film by rotating the pinch of the winder. 2. Twist the film by placing the pinch of the winder and the winder itself on a rotary table and rotating them. 4. Rotate the die device to twist the film. Twist the film by placing the die device and extruder on a rotary table and rotating them.

However, in the above methods 1 and 2, troubles such as scratches on the film, fluctuations in the folding width of the film, and wrinkles and sagging of the film may occur. In the above method 3, since it is necessary to slide the connecting portion of the molten resin supplied from the extruder to the die device, there is a problem that the molten resin leaks or the durability is lowered. Further, in the above method 3, since the die device is rotated with respect to the central axis, the connecting portion must also be installed along the central axis, and is applicable only to single-layer extrusion. In the above methods 1 to 4, a rotating facility is required and the cost is high. In addition, the installation space of the device becomes large. In particular, in the above method 4, since the extruder and the die device are rotated, the rotating equipment becomes large-scale.

From the above findings, the present inventor has come to obtain the film molding apparatus according to the present embodiment. Hereinafter, a specific description will be given.

(First Embodiment)
FIG. 1 shows a schematic configuration of the film molding apparatus 1 according to the first embodiment. The film forming apparatus 1 forms a tubular film. The film forming apparatus 1 includes a die apparatus 2, a cooling apparatus 3, a pair of stabilizers 4, a pair of pinch rolls 5, a thickness sensor 6, a control device 7, and a winder 20.

The die device 2 forms a molten resin supplied from an extruder (not shown) into a tube shape. The die device 2 particularly forms the molten resin into a tube shape by extruding the molten resin from a ring-shaped slit 18 (described later in FIG. 2). The cooling device 3 is arranged above the die device 2. The cooling device 3 blows cooling air from the outside onto the molten resin extruded from the die device 2. The molten resin is cooled and a film is formed.

The pair of stabilizers 4 are arranged above the cooling device 3 and guide the molded film between the pair of pinch rolls 5. The pinch roll 5 is arranged above the stabilizer 4 and folds flat while pulling up the guided film. The winder 20 winds the folded film to form the film roll body 11.

The thickness sensor 6 is arranged between the cooling device 3 and the stabilizer 4. The thickness sensor 6 continuously measures the film thickness at each position in the circumferential direction while rotating around the tubular film. That is, the thickness sensor 6 continuously measures the thickness profile of the film in the circumferential direction. The thickness sensor 6 sends the measured thickness profile to the control device 7. The thickness sensor 6 may send a thickness profile obtained by averaging the measurement results of two or more turns to the control device 7. The control device 7 sends a control command according to the thickness profile received from the thickness sensor 6 to the die device 2. In response to this control command, the die device 2 adjusts the width of the slit 18 (particularly its discharge port) so that the variation in thickness becomes small.

FIG. 2 is a cross-sectional view showing the die device 2 and the cooling device 3 and their surroundings. FIG. 3 is a top view of the die device 2. In FIG. 3, the display of the cooling device 3 is omitted.

The cooling device 3 includes an air ring 8 and an annular rectifying member 9. The air ring 8 is a ring-shaped housing having an inner peripheral portion recessed downward. A ring-shaped outlet 8a opened on the upper side is formed on the inner peripheral portion of the air ring 8. The outlet 8a is formed so as to be concentric with the ring-shaped slit 18 centered on the central axis A.

In the following, the direction parallel to the central axis A will be the axial direction, the arbitrary direction passing through the central axis A on the plane perpendicular to the central axis A will be the radial direction, and the side close to the central axis A in the radial direction will be inside. The circumferential side and the side far from the central axis A will be the outer peripheral side, and the direction along the circumference of the circle centered on the central axis A on the plane perpendicular to the central axis A will be described as the circumferential direction.

A plurality of hose ports 8b are formed on the outer peripheral portion of the air ring 8 at equal intervals in the circumferential direction. A hose (not shown) is connected to each of the plurality of hose ports 8b, and cooling air is sent into the air ring 8 from a blower (not shown) through the hose. The cooling air sent into the air ring 8 is blown out from the air outlet 8a and blown onto the molten resin.

The rectifying member 9 is arranged in the air ring 8 so as to surround the air outlet 8a. The rectifying member 9 rectifies the cooling air sent into the air ring 8. As a result, the cooling air is blown out from the outlet 8a at a uniform flow rate and wind speed in the circumferential direction.

The die device 2 includes a die main body 10, an inner peripheral member 12, an outer peripheral member 14, and a plurality of (32 in this case) adjusting portions 16. The inner peripheral member 12 is a substantially columnar member mounted on the upper surface of the die body 10. The outer peripheral member 14 is an annular member and surrounds the inner peripheral member 12. A slit 18 extending in the vertical direction in a ring shape is formed between the inner peripheral member 12 and the outer peripheral member 14. The molten resin flows upward through the slit 18, the molten resin is extruded from the discharge port (that is, the upper end opening) 18a of the slit 18, cooled by the cooling device 3, and a film having a thickness corresponding to the width of the discharge port 18a. Is formed.

The plurality of adjusting portions 16 are arranged so as to surround the upper end side of the outer peripheral member 14 with almost no gap in the circumferential direction. The adjusting portion 16 is particularly cantileverly attached to the outer peripheral member 14. A cooling device 3 is fixed above the plurality of adjusting portions 16. Each of the plurality of adjusting portions 16 is configured to be able to apply a radial inward pressing load or a radial outward tensile load to the outer peripheral member 14. The outer peripheral member 14 is elastically deformed by applying a pressing load or a tensile load. Therefore, by adjusting the plurality of adjusting portions 16, the width of the discharge port 18a can be partially adjusted in the circumferential direction, and the thickness of the film can be partially controlled in the circumferential direction. When the thickness of the film varies, for example, a tensile load is applied to the outer peripheral member 14 from the adjusting portion 16 corresponding to the thin portion (for example, located below the thin portion) to apply the tensile load to the thin portion. The gap of the discharge port 18a below the thin portion is increased. As a result, the variation in film thickness is reduced.

As an example, as shown in FIG. 2, the adjusting unit 16 is supported by a rotating shaft 32 as a fulcrum, and is supported by a lever 34 that receives the rotational force of the actuator 24 and a die device 2 that is displaceable in the axial direction. Includes an actuating rod 36 supported at 34 points of action. Then, the rotational force of the lever 34 is converted into a force in the axial direction of the operating rod 36, and the force in the axial direction becomes a load on the inner peripheral member 12 or the outer peripheral member 14, and the lever 34 becomes the operating rod 36 at the point of action of the lever 34. Gives power directly to.

FIG. 4 is a block diagram schematically showing the functions and configurations of the control device 7. Each block shown here can be realized by elements such as the CPU of a computer or a mechanical device in terms of hardware, and can be realized by a computer program or the like in terms of software, but here, it is realized by their cooperation. The functional block is drawn. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by combining hardware and software.

The control device 7 includes an acquisition unit 80, a profile holding unit 81, a target profile generation unit 82, a target profile holding unit 83, and an adjusting unit control unit 84. The acquisition unit 80 acquires the measurement result by the thickness sensor 6, that is, the thickness profile of the film in the circumferential direction.

The profile holding unit 81 holds the thickness profile acquired by the acquisition unit 80. The target profile holding unit 83 holds the target thickness profile generated by the target profile generating unit 82 as described later.

FIG. 5A is a diagram schematically showing an example of a profile held by the profile holding unit 81, and FIG. 5B is a diagram schematically showing a target thickness profile held by the target profile holding unit 83. It is a figure which shows. In FIGS. 5A and 5B, the horizontal axis represents the angular position in the circumferential direction, and the vertical axis represents the film thickness. The alternate long and short dash line 90 indicates a reference film thickness, which is an ideal film thickness set by the user. Line 92 of the alternate long and short dash line indicates an allowable thickness range determined based on the reference film thickness.

The target profile generation unit 82 generates a target thickness profile. As will be described later, until the thickness profile falls within the allowable thickness range, the reference film thickness is set as the target thickness profile which is the target of the film thickness, and the die device 2 is controlled so as to approach the reference film thickness as the target thickness profile. To. After the thickness profile falls within the allowable thickness range, the die device 2 is controlled so as to approach the target thickness profile generated by the target profile generation unit 82. Here, if the die device 2 is controlled so that the thickness profile approaches the reference film thickness even after the thickness profile falls within the allowable thickness range, the film thickness can be maintained within the allowable thickness range. However, the film contains some variation in film thickness. Therefore, even if the film thickness is maintained within the allowable thickness range, humps and dents can be formed in the film roll body 11. Therefore, in the present embodiment, the target profile generation unit 82 prevents the film roll body 11 from having humps or dents after the thickness profile is within the allowable thickness range, that is, the thickness of the film roll body 11 is wide. Change the target thickness profile so that it is uniform in the direction.

Specifically, the target profile generation unit 82 makes the film thickness thinner than the reference film thickness at the position where the film thickness is thicker than the reference film thickness, and is smaller than the reference film thickness at the position where the film thickness is thinner than the reference film thickness. A profile with a thicker film is set as a target thickness profile (see FIGS. 5A and 5B). In the present embodiment, the target profile generation unit 82 generates a profile obtained by reversing the measured thickness profile (thickness profile held by the profile holding unit 81) with respect to the reference film thickness as the target thickness profile.

Returning to FIG. 4, the adjusting unit control unit 84 controls a plurality of adjusting units 16 based on the reference film thickness and the target thickness profile held by the target profile holding unit 83. The adjusting unit control unit 84 first controls a plurality of adjusting units 16 based on the reference film thickness as the target thickness profile, and when the film thickness falls within the allowable thickness range, it is generated based on the measured thickness profile. The plurality of adjusting units 16 are controlled based on the target thickness profile, that is, the target thickness profile held by the target profile holding unit 83.

Specifically, the adjusting unit control unit 84 refers to the target thickness profile (that is, the reference film thickness or the target thickness profile held by the target profile holding unit 83), and the measured film thickness exceeds the target thickness profile. A control command is transmitted to the adjusting unit 16 corresponding to the portion in the circumferential direction (that is, the wall thickness is thick) so as to apply a pressing load corresponding to the difference from the target thickness profile to the outer peripheral member 14. As a result, the radial gap of the corresponding discharge port 18a is narrowed, the film thickness of the corresponding portion is thinned, and the target thickness profile is approached. Further, in the adjusting unit control unit 84, the adjusting unit 16 corresponding to the portion in the circumferential direction in which the film thickness is less than the target thickness profile (that is, the wall thickness is thin) is subjected to a tensile load according to the difference from the target thickness profile. Is transmitted to the outer peripheral member 14. As a result, the radial gap of the corresponding discharge port 18a becomes wider, the film thickness of the corresponding portion becomes thicker, and the target thickness profile is approached.

The operation of the film forming apparatus 1 configured as described above will be described.
FIG. 6 is a flowchart showing the processing of the film forming apparatus 1. The process shown in FIG. 6 is a loop process that is repeatedly executed at regular intervals. For example, when the thickness sensor 6 measures the thickness profile obtained by averaging the measurement results for five laps, the thickness sensor 6 may be repeatedly executed every time required for the thickness sensor 6 to make five laps around the film.

The thickness sensor 6 measures the thickness profile of the film in the circumferential direction (S10). If the film thickness is not within the permissible thickness range based on the reference film thickness (N in S12), the control device 7 is a die device based on the reference film thickness so that the film thickness approaches the reference film thickness as the target thickness profile. 2 is controlled (S14). When the film thickness falls within the allowable thickness range (Y in S12), the control device 7 inverts the target thickness profile generated based on the measured thickness profile, that is, the measured thickness profile with respect to the reference film thickness. A generated target thickness profile is generated (S16), and the die device 2 is controlled based on the generated target thickness profile so that the film thickness approaches the generated target thickness profile (S18).

According to the film forming apparatus 1 according to the present embodiment described above, the thickness profile of the film is inverted with respect to the reference film thickness at predetermined timing intervals. As a result, when the film roll body 11 is formed, the portion thicker than the reference film thickness and the portion thinner than the reference film thickness are stacked and averaged, so that the thickness of the film roll body 11 is uniform in the width direction. Become. Therefore, the humps and dents of the film roll body 11 can be reduced or reduced without twisting the film as in the conventional case.

(Second Embodiment)
The main difference between the film forming apparatus according to the second embodiment and the film forming apparatus 1 according to the first embodiment is the method of generating the target thickness profile.

In the present embodiment, the target profile generation unit 82 divides the measured thickness profile (thickness profile held by the profile holding unit 81) into a plurality of section profiles, and each of the divided plurality of section profiles is different from the other. Set as the target thickness profile for the section of.

FIG. 7A is a diagram schematically showing an example of a profile held by the profile holding unit 81, and FIG. 7B is a diagram schematically showing a target thickness profile held by the target profile holding unit 83. It is a figure which shows.

In this example, the thickness profile is divided into four section profiles of 0 ° to 90 °, 90 ° to 180 °, 180 ° to 270 °, 270 ° to 360 °, and the section profile of 0 ° to 90 ° is 90 °. A target thickness profile of ~ 180 °, a section profile of 90 ° to 180 ° is a target thickness profile of 180 ° to 270 °, and a section profile of 180 ° to 270 ° is a target thickness profile of 270 ° to 360 °. Let the section profile of ° to 360 ° be the target thickness profile of 0 ° to 90 °. That is, the target thickness profile is obtained by shifting the phase of the measured thickness profile by 90 °. In this case, the target profile generation unit 82 generates the target thickness profile by shifting the phase of the thickness profile by 90 ° each time the process shown in FIG. 6 is repeatedly executed.

According to the film molding apparatus according to the present embodiment, the same effects as those exerted by the film molding apparatus 1 according to the first embodiment are exhibited.

(Third Embodiment)
The main difference between the film forming apparatus according to the third embodiment and the film forming apparatus according to the first embodiment is that the control unit of the adjusting unit controls the film thickness even when the film thickness is within the allowable thickness range. Basically, the plurality of adjusting units 16 are controlled based on the reference film.

In the present embodiment, the target profile generation unit 82 measures by making the film thickness thinner than the reference film thickness at the position where the measured film thickness is thicker than the reference film thickness, as in the first embodiment. For the position where the film thickness is thinner than the reference film thickness, a profile having a film thickness thicker than the reference film thickness is set as a target profile (see FIGS. 5A and 5B).

Unlike the first embodiment, the adjusting unit control unit 84 basically controls a plurality of adjusting units 16 based on the reference film thickness. That is, the adjusting unit control unit 84 first controls a plurality of adjusting units 16 based on the reference film thickness as the target thickness profile, and even after the film thickness falls within the allowable thickness range, it is based on the reference film thickness. Controls a plurality of adjusting units 16. However, when the film thickness falls within the allowable thickness range, the adjustment unit control unit 84 temporarily controls the adjustment unit 16 based on the target thickness profile generated by the target profile generation unit 82 at an arbitrary timing. To do.

That is, in the present embodiment, the plurality of adjusting units 16 are basically controlled so that the film thickness approaches the reference film thickness. However, with respect to the portion of the film thicker than the reference film thickness, the plurality of adjusting units 16 are controlled so that the film thickness is temporarily thinner than the reference film thickness at an arbitrary timing. Further, with respect to a portion of the film thinner than the reference film thickness, a plurality of adjusting units 16 are controlled so that the film thickness is temporarily thicker than the reference film thickness at an arbitrary timing.

According to the film molding apparatus according to the present embodiment, the same effects as those exerted by the film molding apparatus 1 according to the first embodiment are exhibited.

Even after the film thickness falls within the permissible thickness range, the target film thickness at each position in the circumferential direction is temporarily performed at an arbitrary timing while performing the plurality of adjusting portions 16 based on the reference film thickness. May be changed to any thickness within a predetermined range. In this case, it is not necessary for the target profile generation unit 82 to generate the target profile.

The configuration and operation of the film molding apparatus according to the embodiment have been described above. It will be appreciated by those skilled in the art that these embodiments are exemplary and that various modifications are possible in the combination of their respective components, and that such modifications are also within the scope of the present invention.

(Modification example 1)
In the second embodiment, the case where the target profile generation unit 82 generates the target thickness profile by shifting the phase of the thickness profile by 90 ° has been described, but the present invention is not limited to this. The target profile generation unit 82 may generate the target thickness profile by shifting the phase by, for example, 30 °, 45 °, 60 °, 120 °, or other predetermined angle.

Further, in the second embodiment, the target profile generation unit 82 shifts the thickness profile by 90 ° in phase, that is, slides each of the section profiles divided into four to obtain the target thickness profile of the adjacent section. I explained, but it is not limited to this. The divided section profile can be set as the target thickness profile of any section. Further, the thickness profile may be divided into two, three, or five or more section profiles.

(Modification 2)
In the first to third embodiments, the film thickness is partially changed in the circumferential direction by widening or narrowing the radial gap of the discharge port 18a of the slit 18 by the adjusting portion 16. The case where the thickness profile is changed has been described, but the present invention is not limited to this. The film thickness may be partially changed in the circumferential direction to change the thickness profile of the film by partially changing at least one of the air volume and the air temperature of the cooling air blown out from the cooling device 3 in the circumferential direction. In this case, the cooling device 3 may include a plurality of valves for adjusting the air volume and a plurality of heaters in the air ring 8.

(Modification 3)
In the first to third embodiments, the case where the die device 2 is a so-called round die in which the discharge port 18a is annular has been described, but the present invention is not limited to this. The technical idea of the embodiment can also be applied to a so-called T-die having a linear discharge port.

Any combination of the embodiments and modifications described above is also useful as an embodiment of the present invention. The new embodiments resulting from the combination have the effects of the combined embodiments and variants.

1 film forming device, 2 die device, 3 cooling device, 6 thickness sensor, 7 control device, 16 adjustment unit, 82 target profile generator, 84 adjustment unit control unit.

Claims (5)

A die device that extrudes molten resin into a tube to form a film,
A measuring unit that measures the thickness profile of the film in a predetermined direction,
Adjustment means for changing the thickness profile of the film,
A control device for controlling the adjusting means so that the thickness profile approaches the target thickness profile is provided.
The control device is a film forming device that changes a target thickness profile based on a measured thickness profile. The control device makes the film thickness thinner than the reference film thickness at the position where the measured film thickness is thicker than the predetermined reference film thickness, and the reference film at the position where the measured film thickness is thinner than the reference film thickness. The film forming apparatus according to claim 1, wherein a profile having a film thickness thicker than the thickness is set as a target profile. The film forming apparatus according to claim 2, wherein the control device sets a profile obtained by reversing the measured thickness profile with respect to the reference film thickness as a target thickness profile. The control device is characterized in that the measured thickness profile is divided into a plurality of section profiles, and the target thickness profile of the other section is changed based on the section profile of one of the divided section profiles. The film forming apparatus according to claim 1. A die device that extrudes molten resin into a tube to form a film,
A measuring unit that measures the film thickness at each position in a predetermined direction,
Adjusting means for changing the film thickness at each position,
A control device for controlling the adjusting means so that the film thickness at each position approaches the reference film thickness is provided.
The control device controls the adjusting means so that the film thickness is temporarily thinner than the reference film thickness at an arbitrary timing with respect to the portion of the film thicker than the reference film thickness, and is thinner than the reference film thickness. A film forming apparatus characterized in that the adjusting means is controlled so that the film thickness temporarily becomes thicker than the reference film thickness with respect to a film portion at an arbitrary timing.

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