WO2018079213A1

WO2018079213A1 - Longitudinal drawing device

Info

Publication number: WO2018079213A1
Application number: PCT/JP2017/036207
Authority: WO
Inventors: 成光金島; 青木　敦
Original assignee: 東レエンジニアリング株式会社
Priority date: 2016-10-31
Filing date: 2017-10-05
Publication date: 2018-05-03
Also published as: CN110049856A; JP2018069639A; KR20190076016A; JP6622680B2; CN110049856B

Abstract

Provided is a longitudinal drawing device capable of reducing the occurrence of transfer damage, scratches, or the like on a thermoplastic film when drawn longitudinally. Specifically, a longitudinal drawing device 5 draws a thermoplastic film F, heated by heating rolls 13, by means of a difference in peripheral speed between a plurality of low-speed driving rolls 8 and a plurality of high-speed driving rolls 9. The plurality of low-speed driving rolls 8 and the plurality of high-speed driving rolls 9 are respectively composed of suction rolls having low-speed-side suction holes 8b and high-speed-side suction holes 9b which are a plurality of suction holes in conveyance surfaces thereof for conveying the thermoplastic film F. A plurality of the heating rolls 13 are provided between adjacent low-speed driving rolls 8 and high-speed driving rolls 9. Each of the plurality of heating rolls 13 is provided with a following electric motor 15 serving as an actuator. Each of the plurality of heating rolls 13 is configured to be independently rotationally drivable. The output torque of each of the following electric motors 15 is controlled so as to coincide with a target value set for each of the following electric motors 15.

Description

Longitudinal stretching device

The present invention relates to a longitudinal stretching apparatus. Specifically, the present invention relates to a longitudinal stretching apparatus that heats a thermoplastic film and stretches the thermoplastic film in the transport direction.

Conventionally, a thermoplastic film made of a thermoplastic polymer such as polyester, triacetyl cellulose (TAC), polyolefin, and polyamide has been used as a support for packaging films, plate-making substrates, printing films, laminate films, magnetic recording media, optical disks, and the like. Widely used. Such a thermoplastic film such as a polyester resin is known to obtain excellent physical properties by stretching, and is usually used as a uniaxially stretched film or a biaxially stretched film. The biaxially stretched film is produced by transversely stretching after longitudinally uniaxially stretching. When the thermoplastic film is stretched longitudinally, the thermoplastic film is stretched in the flow direction by utilizing the speed difference between the upstream low-speed roll and the downstream high-speed roll. At this time, by extending the distance between the upstream low-speed roll and the downstream high-speed roll so that the thermoplastic film can be stably stretched without breaking (long span), the amount of elongation of the film per unit time There is a known method for reducing the size. For example, as described in Patent Document 1.

In the longitudinal stretching apparatus described in Patent Document 1, a heating furnace is provided between an upstream low speed roller (low speed roll) and a downstream high speed roller (high speed roll), and a plurality of pass rollers are provided in the heating furnace. It has been. The longitudinal stretching apparatus is a film in which a longitudinal film of a film is stretched by a plurality of pass rollers while a thermoplastic film heated by a heating furnace is stretched by a low-speed roller and a high-speed roller arranged with a wide span. Stable stretching can be performed by preventing undulation. However, since the technique described in Patent Document 1 extends the wrinkles by bringing the thermoplastic film into contact with a plurality of pass rollers, the resistance during conveyance is large. Therefore, the longitudinal stretching apparatus conveys the thermoplastic film while pressing the thermoplastic film with the nip roller so that the thermoplastic film does not slip between the high speed roller and the low speed roller. For this reason, the thermoplastic film may have a transfer flaw on the surface due to the pressing force of the nip roller, or may be scratched by slipping with the pass roller.

JP 2008-221722 A

An object of the present invention is to provide a longitudinal stretching apparatus capable of suppressing the occurrence of transfer scratches, scratches and the like in a thermoplastic film during longitudinal stretching.

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

That is, in the longitudinal stretching apparatus that stretches a thermoplastic film heated by a heating roll by a peripheral speed difference between a plurality of low speed driving rolls and a plurality of high speed driving rolls having a peripheral speed larger than that of the low speed driving roll, the plurality of low speeds The drive roll and the plurality of high-speed drive rolls are constituted by suction rolls having a plurality of suction holes on the thermoplastic film conveyance surface, and a plurality of heating between the low-speed drive roll and the high-speed drive roll adjacent to each other. A plurality of low-speed drive rolls, a plurality of high-speed drive rolls, and a plurality of heating rolls, and a plurality of low-speed drive rolls, a plurality of high-speed drive rolls, and a plurality of heating rolls. The rolls can be driven independently of each other, and the output torque of each actuator is And it is controlled so as to coincide with the target value set for each mediator.

In the longitudinal stretching apparatus, the actuators are connected to the plurality of low-speed drive rolls, the plurality of high-speed drive rolls, and the plurality of heating rolls via a torque control device, respectively, and the difference between the output torque and the target value is When larger than the specified value, a rotational speed difference is generated between the input shaft and the output shaft of the torque control device so as to maintain the rotational speed of the output shaft of the torque control device connected to the actuator, When the difference between the output torque and the target value is smaller than the specified value, the rotational speed difference between the input shaft and the output shaft of the torque control device connected to the actuator is not generated. is there.

In the longitudinal stretching device, the torque control device is constituted by a powder clutch, and the torque transmission amount is controlled based on the target value.

The longitudinal stretching apparatus is configured such that the plurality of heating rolls can be independently temperature controlled.

As the effects of the present invention, the following effects are obtained.

In the longitudinal stretching apparatus, since the resistance when the thermoplastic film is conveyed by the heating roll is small, it is not necessary to apply a friction force by pressing the thermoplastic film with a nip roller between the low speed driving roll and the high speed driving roll. Further, no slip occurs between the plurality of heating rolls and the thermoplastic film that are independently driven and controlled. Thereby, generation | occurrence | production of a transfer damage | wound, an abrasion, etc. can be suppressed in the thermoplastic film at the time of longitudinal stretching.

In the longitudinal stretching apparatus, when the conveyance speed of the thermoplastic film fluctuates, the heating roll rotates following the thermoplastic film regardless of the control of the actuator. Thereby, generation | occurrence | production of a transfer damage | wound, an abrasion, etc. can be suppressed in the thermoplastic film at the time of longitudinal stretching.

In the longitudinal stretching apparatus, the rotational speed of the heating roll is controlled based on the conveyance speed and stretching amount of the thermoplastic film. Thereby, generation | occurrence | production of a transfer damage | wound, an abrasion, etc. can be suppressed in the thermoplastic film at the time of longitudinal stretching.

In the longitudinal stretching apparatus, the thermoplastic film is stretched at a predetermined stretching ratio, so that speed fluctuation is unlikely to occur. Thereby, generation | occurrence | production of a transfer damage | wound, an abrasion, etc. can be suppressed in the thermoplastic film at the time of longitudinal stretching.

Schematic which shows the whole structure in one Embodiment of a manufacturing apparatus provided with a longitudinal stretch apparatus. Schematic which shows the whole structure in one Embodiment of a longitudinal stretch apparatus. The front view which shows the structure of the low speed drive roll and high speed drive roll in one Embodiment of a longitudinal stretch apparatus. The front view which shows the structure of the heating roll and cooling roll in one Embodiment of a longitudinal stretch apparatus. The block diagram which shows the control structure in one Embodiment of a longitudinal stretch apparatus. The schematic diagram which shows the operation | movement aspect in the slip suppression control of a heating roll in one Embodiment of a longitudinal stretch apparatus. The figure which shows the graph showing the fluctuation | variation of the driving torque in the slip suppression control of a heating roll in one Embodiment of a longitudinal stretch apparatus.

First, the manufacturing apparatus 1 provided with the longitudinal stretch apparatus 5 which is one Embodiment of the longitudinal stretch apparatus which concerns on this invention is demonstrated using FIG. In addition, although the manufacturing apparatus 1 manufactures the thermoplastic film F which consists of thermoplastic polymers, such as polyester, a triacetyl cellulose (TAC), polyolefin, and polyamide, in this embodiment, it is from triacetyl cellulose (TAC). It demonstrates as what manufactures the thermoplastic film F which becomes.

As shown in FIG. 1, the manufacturing apparatus 1 processes the thermoplastic polymer which consists of triacetylcellulose (TAC), and manufactures the thermoplastic film F which consists of desired film thickness. The production apparatus 1 includes a melt extrusion apparatus 2, a slit die 3, a casting roll 4, a longitudinal stretching apparatus 5, a lateral stretching apparatus 6, and a winding apparatus 7.

The manufacturing apparatus 1 heats and melts a chip-shaped thermoplastic polymer by a melt extrusion apparatus 2 and extrudes it from a slit die 3. The manufacturing apparatus 1 makes the thermoplastic polymer continuously extruded from the slit-shaped die 3 adhere to the casting roll 4 and is cured into a sheet shape. That is, the manufacturing apparatus 1 forms the unstretched thermoplastic film F from the chip-shaped thermoplastic polymer. Furthermore, the manufacturing apparatus 1 continuously stretches the unstretched thermoplastic film F formed in the conveying direction (longitudinal direction) by the longitudinal stretching apparatus 5 to form the longitudinally stretched thermoplastic film F. . Next, the manufacturing apparatus 1 forms the thermoplastic film F biaxially stretched by continuously stretching the thermoplastic film F in the width direction (lateral direction) by the lateral stretching apparatus 6. The manufacturing apparatus 1 causes the formed thermoplastic film F to be wound around the core material by the winding apparatus 7.
By comprising in this way, the manufacturing apparatus 1 can form continuously the thermoplastic film F biaxially stretched from the chip-shaped thermoplastic polymer to the vertical direction and the horizontal direction.

Hereinafter, the longitudinal stretching apparatus 5 as an embodiment of the longitudinal stretching apparatus according to the present invention will be described with reference to FIGS. The longitudinal stretching device 5 stretches the unstretched thermoplastic film F in the transport direction (hereinafter referred to as “longitudinal direction”). The longitudinal stretching apparatus 5 includes a plurality of low-speed drive rolls 8, a plurality of high-speed drive rolls 9, a suction pump 10, a low-speed electric motor 11, a high-speed electric motor 12, a plurality of heating rolls 13, a plurality of cooling rolls 14, and a plurality of cooling rolls 14. A follow-up electric motor 15, a plurality of powder clutches 16, and a control device 17 are provided.

As shown in FIG. 2, the low-speed drive roll 8 extends the unstretched thermoplastic film F together with the high-speed drive roll 9 in the longitudinal direction. The low speed drive roll 8 is disposed on the most upstream side of the longitudinal stretching device 5. In the present embodiment, a plurality of low speed drive rolls 8 are arranged in the longitudinal stretching device 5. The low-speed drive roll 8 is a metal roll, and has been subjected to surface treatment such as hard chrome plating, tungsten carbide spraying, fluororesin coating, or ceramic coating. The low speed drive roll 8 is arranged so that the thermoplastic film F is wound around the low speed drive roll 8 at a predetermined wrap angle.
As shown in FIG. 3, a plurality of holes penetrating the inside of the roll are formed on the low-speed side conveyance surface 8 a that is a surface (hereinafter, simply referred to as “conveyance surface”) that the thermoplastic film F of the low-speed drive roll 8 contacts. Is formed. Further, the low-speed drive roll 8 is configured such that the inside of the roll is sucked by the suction pump 10 (see the thin ink portion in FIG. 2). Thereby, the low-speed drive roll 8 is configured so that the hole of the low-speed side conveying surface 8a acts as the low-speed side suction hole 8b and can adsorb and hold the thermoplastic film F.

As shown in FIG. 2, the high-speed drive roll 9 extends the unstretched thermoplastic film F together with the low-speed drive roll 8 in the longitudinal direction. The high-speed drive roll 9 is disposed on the most downstream side of the longitudinal stretching device 5. In the present embodiment, the longitudinal stretching device 5 is provided with a plurality of high-speed drive rolls 9. The high-speed drive roll 9 is a metal roll, and has been subjected to surface treatment such as hard chrome plating, tungsten carbide thermal spraying, fluororesin coating, or ceramic coating. The high-speed drive roll 9 is disposed so that the thermoplastic film F is wound around the high-speed drive roll 9 with a predetermined wrap angle.
As shown in FIG. 3, the high-speed drive roll 9 has a plurality of holes penetrating into the roll on the high-speed side conveying surface 9a with which the thermoplastic film F comes into contact. Further, the plurality of high-speed drive rolls 9 are configured such that the inside of the roll is sucked by the suction pump 10 (see the thin ink portion in FIG. 2). Accordingly, the plurality of high-speed drive rolls 9 are configured such that the holes of the high-speed side conveyance surface 9a act as the high-speed side suction holes 9b and can adsorb and hold the thermoplastic film F.

The low-speed electric motor 11 and the high-speed electric motor 12 that are actuators rotate the plurality of low-speed drive rolls 8 and the plurality of high-speed drive rolls 9, respectively. Each of the low speed electric motor 11 and the high speed electric motor 12 is connected to a vector inverter included in the control device 17 (see FIG. 5), and is configured to be independently torque controlled. The low-speed electric motor 11 is provided for each low-speed drive roll 8 via a powder clutch 16 that is a torque control device, and the high-speed electric motor 12 is provided for each high-speed drive roll 9 via a powder clutch 16. ing. That is, the plurality of low-speed electric motors 11 can independently drive and control the low-speed drive rolls 8 connected thereto. Similarly, the plurality of high-speed electric motors 12 can independently drive and control a plurality of low-speed drive rolls 8 connected thereto.

Each high-speed drive roll 9 is draw-controlled with respect to each low-speed drive roll 8. That is, each high-speed drive roll 9 is driven so as to have a higher peripheral speed than each low-speed drive roll 8. The thermoplastic film F is fed from the upstream side by a plurality of low-speed drive rolls 8 at a predetermined unit feed speed, and downstream by a plurality of high-speed drive rolls 9 at a predetermined unit feed speed greater than the feed speed of the low-speed drive rolls 8. It is carried in toward the side. Thereby, the plurality of low-speed drive rolls 8 and the plurality of high-speed drive rolls 9 are different from each other only in the difference between the unit feed amount at a predetermined feed speed and the unit feed amount at a predetermined feed speed between the pitches of the thermoplastic film F. It is configured to stretch.

As shown in FIG. 2, the heating roll 13 heats the thermoplastic film F. The heating roll 13 is disposed between the most downstream low-speed drive roll 8 and the most upstream high-speed drive roll 9. In the present embodiment, the longitudinal stretching device 5 is provided with a plurality of heating rolls 13. The heating roll 13 is a metal roll, and has been subjected to surface treatment such as hard chrome plating, tungsten carbide thermal spraying, fluororesin coating, or ceramic coating. The heating roll 13 is disposed so that the thermoplastic film F is wound around the heating roll 13 at a predetermined wrap angle.
As shown in FIG. 4, each heating roll 13 includes a heating temperature sensor that is a temperature measuring unit that measures the temperature of the heating and conveying surface 13 a that the cartridge heater 13 b that is a heating unit and the thermoplastic film F of the heating roll 13 are in contact with each other. 13c is provided. The cartridge heaters 13b and the heating temperature sensors 13c provided in each heating roll 13 independently set the heating and conveying surface 13a of the heating roll 13 at a predetermined temperature by a control signal from the control device 17 (see FIG. 5). It is configured to be heated and maintained. In the present embodiment, the heating means of the heating roll 13 is the cartridge heater 13b. However, the present invention is not limited to this, and a heating device or induction heating device by circulation of a heating medium such as hot water, pressurized hot water, or heating oil. Etc.

As shown in FIG. 2, the cooling roll 14 cools the thermoplastic film F. The cooling roll 14 is disposed between the most downstream heating roll 13 and the most upstream high-speed drive roll 9. In the present embodiment, the longitudinal stretching apparatus 5 is provided with a plurality of cooling rolls 14. The cooling roll 14 is a metal roll, and has been subjected to surface treatment such as hard chrome plating, tungsten carbide thermal spraying, fluorine resin coating, ceramic coating, or the like. The cooling roll 14 is arranged so that the thermoplastic film F is wound around each cooling roll 14 at a predetermined wrap angle.
As shown in FIG. 4, the plurality of cooling rolls 14 includes a cooling temperature sensor 14 c that is a temperature measurement unit that measures a cooling conveyance surface 14 a that contacts a heat pipe 14 b that is a cooling unit and a thermoplastic film F of the cooling roll 14. Each is provided. The heat pipes 14b and the cooling temperature sensors 14c provided in the plurality of cooling rolls 14 independently cool the cooling conveyance surfaces 14a of the respective cooling rolls 14 by a control signal from the control device 17 (see FIG. 5). Is configured to do. In the present embodiment, the cooling means of the cooling roll 14 is the heat pipe 14b, but is not limited to this, and may be a piezo element or a cooling device by circulating a heat medium.

The follow-up electric motor 15 that is an actuator rotates the heating roll 13 and the cooling roll 14. The follow-up electric motor 15 is provided on each heating roll 13 and each cooling roll 14 via a powder clutch 16 that is a torque control device. Each of the follow-up electric motors 15 is connected to a vector inverter included in the control device 17 (see FIG. 5), and is configured to be torque-controlled independently of each other. That is, the plurality of follow-up electric motors 15 are configured so that the heating roll 13 or the cooling roll 14 connected thereto can be independently driven and controlled.

As shown in FIG. 3 and FIG. 4, the plurality of powder clutches 16 that are torque control devices include transmission torque between the low-speed drive roll 8 and the low-speed electric motor 11, the high-speed drive roll 9 and the high-speed electric motor 12. The transmission torque between the heating roll 13 and the follow-up electric motor 15 or the transfer torque between the cooling roll 14 and the follow-up electric motor 15 is limited. The powder clutch 16 generates friction by applying magnetic flux to magnetic iron powder (powder) interposed between the input shaft 16a and the output shaft 16b, and torque is transmitted between the input shaft 16a and the output shaft 16b. Switch to the status. In the present embodiment, each powder clutch 16 is connected to the input shaft 16a of any one of a plurality of low-speed electric motors 11, a plurality of high-speed electric motors 12, or a plurality of follow-up electric motors 15, respectively. Any one of a plurality of low-speed drive rolls 8, a plurality of high-speed drive rolls 9, a plurality of heating rolls 13, or a plurality of cooling rolls 14 is connected to the output shaft 16b. In other words, each powder clutch 16 includes a transmission torque between the low-speed drive roll 8 and the low-speed electric motor 11, a transmission torque between the high-speed drive roll 9 and the high-speed electric motor 12, a heating roll 13 and a follow-up electric motor. 15 or a transmission torque between the cooling roll 14 and the follow-up electric motor 15 can be arbitrarily set. Each powder clutch 16 is connected to a control device 17 (see FIG. 5) and configured to be able to control the magnitude of the transmission torque independently of each other.

As shown in FIG. 5, the control device 17 controls the longitudinal stretching device 5. The control device 17 may actually have a configuration in which a CPU, a ROM, a RAM, an HDD, and the like are connected by a bus, or may be configured by a one-chip LSI or the like. The control device 17 is connected to a control device of the manufacturing device 1 (not shown), and stores various programs and data for controlling the longitudinal stretching device 5 and the like.

The control device 17 is connected to the low-speed electric motor 11 of each low-speed drive roll 8 and the high-speed electric motor 12 of each high-speed drive roll 9 and is driven to each low-speed electric motor 11 and each high-speed electric motor 12. It is possible to control to output an arbitrary driving torque Td by transmitting a command value related to torque. In addition, the control device 17 can acquire the actual drive torque from each low-speed electric motor 11 and each high-speed electric motor 12.

The control device 17 is connected to the suction pump 10 and can control the suction pump 10.

The control device 17 is connected to each cartridge heater 13b and each heating temperature sensor 13c provided in each heating roll 13, and needs to acquire the actual temperature of the corresponding heating roll 13 from each heating temperature sensor 13c. is there. Further, the control device 17 can control to maintain a predetermined temperature by transmitting a temperature command value to each cartridge heater 13b.

The control device 17 is connected to each cooling temperature sensor 14c provided in each cooling roll 14, and needs to acquire the actual temperature of the corresponding cooling roll 14 from each cooling temperature sensor 14c.

The control device 17 is connected to the follow-up electric motor 15 of each heating roll 13 and the follow-up electric motor 15 of each cooling drive roll. Control can be performed to output the drive torque Td. Further, the control device 17 can acquire the actual driving torque from each of the follow-up electric motors 15.

The control device 17 is connected to each powder clutch 16 and transmits a command value related to an arbitrary transmission torque to control the torque to be transmitted between the input shaft 16a and the output shaft 16b below the arbitrary transmission torque. Can do.

The longitudinal stretching apparatus 5 configured as described above feeds the thermoplastic film F by a plurality of low-speed drive rolls 8 while adsorbing and holding the thermoplastic film F by a predetermined unit feed amount. The longitudinal stretching device 5 heats the thermoplastic film F fed from the low-speed drive roll 8 to a predetermined temperature by the plurality of heating rolls 13. On the other hand, the longitudinal stretching device 5 feeds the thermoplastic film F heated by the heating roll 13 by a predetermined unit feed amount while adsorbing and holding the thermoplastic film F by the plurality of high-speed drive rolls 9. Thereby, the longitudinal stretching apparatus 5 stretches the heated thermoplastic film F longitudinally by the difference between the unit feeding amount at a predetermined feeding speed and the unit feeding amount at a predetermined feeding speed. Then, the longitudinal stretching device 5 cools the thermoplastic film F to a predetermined temperature with a plurality of cooling rolls 14. The longitudinal stretching device 5 extends the interval between the plurality of low-speed drive rolls 8 and the plurality of high-speed drive rolls 9 to stretch the thermoplastic film F, thereby reducing the amount of elongation per unit time of the thermoplastic film F, The load on the film during stretching can be reduced. In the present embodiment, the actuator is constituted by an electric motor including the low-speed electric motor 11, the high-speed electric motor 12, and the follow-up electric motor 15. However, the present invention is not limited to this, and any actuator can be used. Good.

Hereinafter, with reference to FIGS. 3, 6, and 7, the manner of holding the thermoplastic film F in the plurality of low-speed drive rolls 8 and the plurality of high-speed drive rolls 9, and the low-speed drive roll 8, the plurality of high-speed drives The aspect at the time of extending | stretching of the thermoplastic film F by the roll 9, the some heating roll 13, and the some cooling roll 14 is demonstrated. In the present embodiment, the longitudinal stretching device 5 includes four low-speed drive rolls 8, three high-speed drive rolls 9, four heating rolls 13, and four cooling rolls 14. It is not limited.

As shown in FIG. 3, the plurality of low-speed drive rolls 8 of the longitudinal stretching apparatus 5 in the present embodiment uses the thermoplastic film F wound around each low-speed side conveyance surface 8 a at a predetermined wrap angle on the conveyance surface. Adsorption is held by holes formed on the entire surface. That is, each low-speed drive roll 8 sucks and holds the entire area of the thermoplastic film F that is in contact with the low-speed transport surface 8a. For this reason, each low-speed drive roll 8 can hold the thermoplastic film F with a smaller pressure than the case where it is pressed and held by the nip roller. In each low-speed drive roll 8, the thermoplastic film F is pressed against the low-speed transport surface 8a by air that is a gas. For this reason, each low-speed drive roll 8 can hold | maintain the thermoplastic film F by a more uniform pressure than the case where it press-holds with the nip roller which is solid. That is, each low-speed drive roll 8 is unlikely to cause local pressure concentration on the thermoplastic film F. Thereby, the low speed drive roll 8 in the present embodiment can suppress the generation of transfer scratches on the surface of the thermoplastic film F by adsorbing and holding the thermoplastic film F. The same applies to the plurality of high-speed drive rolls 9.

Next, slip suppression control in the plurality of low-speed drive rolls 8, the plurality of high-speed drive rolls 9, the plurality of heating rolls 13, and the plurality of cooling rolls 14 will be described with reference to FIGS. In the present embodiment, the slip suppression control in the heating roll 13 will be described, and the description of the plurality of low-speed drive rolls 8, the plurality of high-speed drive rolls 9, and the plurality of cooling rolls 14 in which similar control is performed will be omitted.

As shown in FIG. 6, the thermoplastic film F is wound around each heating conveyance surface 13a of each heating roll 13 of the longitudinal stretching apparatus 5 in this embodiment at a predetermined wrap angle. The plurality of heating rolls 13 are rotationally driven so as to follow the thermoplastic film F by a follow-up electric motor 15 (see FIG. 4) connected thereto. That is, the heating roll 13 is controlled to synchronize with the transport speed Vt of the thermoplastic film F. The thermoplastic film F is transported while being stretched in the vertical direction so that the transport speed Vt increases from a predetermined feed speed of the low-speed drive roll 8 to a predetermined feed speed of the high-speed drive roll 9. For this reason, as for the thermoplastic film F, the conveyance speed Vt changes with the conveyance path positions. Accordingly, the plurality of heating rolls 13 are configured such that the rotational speed Vr (circumferential speed) is independently controlled so as to be able to follow the transport speed Vt of the thermoplastic film F that differs for each arrangement.

As shown in FIG. 4, the plurality of heating rolls 13 are limited in transmission torque with the follow-up electric motor 15 connected via the respective powder clutch 16 (see FIG. 4). In each powder clutch 16, the driving torque Td of the follow-up electric motor 15 is transmitted to the input shaft 16a, and is transmitted to the output shaft 16b as the rotational torque Tr necessary for rotating the heating roll 13 at a predetermined speed. . In the powder clutch 16, when a difference of a predetermined value Tg or more occurs between the driving torque Td transmitted to the input shaft 16a and the rotational torque Tr transmitted to the output shaft 16b, the input shaft 16a and the output shaft 16b The rotational speed difference is generated between the input shaft 16a and the output shaft 16b.

One heating roll 13 arranged at an arbitrary position among the plurality of heating rolls 13 is provided to the follow-up electric motor 15 so that the peripheral speed determined from the rotation speed Vr matches the transport speed Vt of the thermoplastic film F. It is rotationally driven. When the transport speed Vt of the thermoplastic film F is the reference transport speed Vt0, the follow-up electric motor 15 is configured so that the peripheral speed determined from the rotational speed Vr of the one heating roll 13 matches the transport speed Vt of the thermoplastic film F. The necessary drive torque Td is controlled as the reference drive torque Td0.

As shown in FIG. 6A, the transport speed Vt of the thermoplastic film F is the reference transport speed Vt0, and the transport speed Vt and the peripheral speed determined by the rotational speed Vr of the one heating roll 13 coincide with each other. The rotational speed Vr of the heating roll 13 is not affected by the thermoplastic film F being conveyed.
As shown in FIG. 7, the drive torque Td transmitted to the input shaft 16a and the output shaft 16b of the powder clutch 16 and the output shaft 16b until the time t1 when the thermoplastic film F is transported at the transport speed Vt0. The transmitted rotational torque Tr becomes the reference driving torque Td0. That is, there is no difference greater than the specified value Tg between the input shaft 16a and the output shaft 16b of the powder clutch 16, so that the input shaft 16a and the output shaft 16b do not deviate and each shaft has the same rotational speed Vr. It is rotating (see FIG. 6A). As a result, since the heating roll 13 rotates following the thermoplastic film F being conveyed, the occurrence of slippage between the thermoplastic film F and the conveyance surface of the heating roll 13 is suppressed.

As shown in FIG. 6B, in one heating roll 13, the conveyance speed Vt of the thermoplastic film F is larger than the reference conveyance speed Vt0 and is higher than the peripheral speed determined by the rotation speed Vr of the one heating roll 13. When the conveyance speed Vt1 becomes high, the external force Fr1 is applied in the direction in which the rotational speed Vr of the heating roll 13 is increased by the thermoplastic film F. Thereby, the rotational torque Tr transmitted to the output shaft 16b of the output shaft 16b of the powder clutch 16 varies. When a difference of a specified value Tg or more occurs between the driving torque Td transmitted to the input shaft 16a and the rotational torque Tr transmitted to the output shaft 16b of the powder clutch 16, the powder clutch 16 and the input shaft 16a The phase with the output shaft 16b is shifted, and a rotational speed difference is generated between the input shaft 16a and the output shaft 16b. That is, the rotational speed Vr (peripheral speed) of one heating roll 13 is increased to a rotational speed Vr1 that is a peripheral speed that matches the transport speed Vt1 of the thermoplastic film F by the external force Fr1 from the thermoplastic film F. As a result, the one heating roll 13 is heated with the thermoplastic film F because the rotational speed Vr increases following the thermoplastic film F by the external force Fr1 even if the conveyance speed Vt of the thermoplastic film F increases. The occurrence of slippage between the roll 13 and the conveying surface is suppressed.

As shown in FIG. 7, the driving torque Td of one follow-up electric motor 15 that rotationally drives one heating roll 13 is a direction in which the external force Fr1 from the thermoplastic film F assists the rotation of the one heating roll 13. As a result, the driving torque Td1 decreases from time t1 to time t2. When the control device 17 detects a decrease in the drive torque Td of the one follow-up electric motor 15, the control device 17 performs control so as to increase the reduced drive torque Td1 of the one follow-up electric motor 15. That is, the control device 17 controls the drive torque Td so that the rotation speed Vr of one heating roll 13 becomes the rotation speed Vr1 (see FIG. 6B). Thereby, the heating roll 13 is rotated so as to follow the transport speed Vt of the thermoplastic film F.

As shown in FIG. 6 (c), in one heating roll 13, when the conveyance speed Vt of the thermoplastic film F becomes a conveyance speed Vt2 smaller than the peripheral speed determined by the rotation speed Vr of the one heating roll 13, An external force Fr2 is applied in the direction of decreasing the rotational speed Vr of the heating roll 13 by the thermoplastic film F, and the rotational torque Tr transmitted to the output shaft 16b of the powder clutch 16 varies. When a difference of a specified value Tg or more occurs between the driving torque Td transmitted to the input shaft 16a of the powder clutch 16 and the rotational torque Tr transmitted to the output shaft 16b of the powder clutch 16, the powder clutch 16 The phase of the input shaft 16a and the output shaft 16b is shifted, and a rotational speed difference is generated between the input shaft 16a and the output shaft 16b. That is, the one heating roll 13 has a rotational speed Vr (peripheral speed) that is reduced to a rotational speed Vr2 that is a peripheral speed that matches the transport speed Vt2 of the thermoplastic film F by the external force Fr2 from the thermoplastic film F. As a result, the one heating roll 13 can be heated together with the thermoplastic film F because the rotational speed Vr decreases following the thermoplastic film F by the external force Fr2 even if the transport speed Vt of the thermoplastic film F decreases. The occurrence of slippage between the roll 13 and the conveying surface is suppressed.

As shown in FIG. 7, the driving torque Td of the one follow-up electric motor 15 that rotationally drives the one heating roll 13 is the direction in which the external force Fr2 from the thermoplastic film F hinders the rotation of the one heating roll 13. As a result, the driving torque Td2 increases from time t3 to time t4. When the control device 17 detects an increase in the drive torque Td of the one follow-up electric motor 15, the control device 17 performs control so as to reduce the increased drive torque Td2 of the one follow-up electric motor 15. That is, the control device 17 performs control so that the rotation speed Vr of one heating roll 13 becomes the rotation speed Vr2. Thereby, the heating roll 13 is rotated so as to follow the transport speed Vt of the thermoplastic film F.

With this configuration, the longitudinal stretching apparatus 5 is less likely to cause speed fluctuations because the thermoplastic film F is stretched at a predetermined stretching ratio. Furthermore, since the longitudinal stretching apparatus 5 is controlled so that the plurality of heating rolls 13 and the plurality of cooling rolls 14 actively follow the thermoplastic film F, the thermoplasticity by the heating roll 13 and the cooling roll 14 is controlled. The resistance when the film F is conveyed is small. Therefore, the longitudinal stretching device 5 does not need to apply a frictional force for suppressing slippage by pressing the thermoplastic film F with the nip roller in the low-speed drive roll 8 and the high-speed drive roll 9. Further, in the longitudinal stretching device 5, the rotational speeds Vr of the plurality of heating rolls 13 and the plurality of cooling rolls 14 are independently torque controlled based on the conveyance speed Vt of the thermoplastic film F. Furthermore, when the conveyance speed Vt of the thermoplastic film F changes, the heating roll 13 or the cooling roll 14 is rotated following the thermoplastic film F regardless of the control of the follow-up electric motor 15 by the action of the powder clutch 16. . Therefore, the longitudinal stretching apparatus 5 does not slip between the heating roll 13 and the thermoplastic film F. Thereby, generation | occurrence | production of a transfer flaw, an abrasion, etc. can be suppressed in the thermoplastic film F at the time of longitudinal stretching.

As described above, the longitudinal stretching device 5 in the present embodiment uses the powder clutch 16 as a clutch, but is not limited to this, and any device can be used as long as the transmission torque can be controlled to an arbitrary value. Moreover, although the longitudinal stretch apparatus 5 heats the thermoplastic film F alternately one surface at a time by making the thermoplastic film F contact the heating conveyance surface 13a of the heating roll 13, it is not limited to this, and is sealed The thermoplastic film F may be simultaneously heated from both sides by heating with a type of air heating nozzle. The above-described embodiments are merely representative, and various modifications can be made without departing from the scope of one embodiment. It goes without saying that the present invention can be embodied in various forms, and the scope of the present invention is indicated by the description of the scope of claims, and the equivalent meanings of the scope of claims, and all the scopes within the scope of the claims. Includes changes.

DESCRIPTION OF SYMBOLS 5 Longitudinal drawing apparatus 8 Low speed drive roll 9 High speed drive roll 13 Heating roll 8a Low speed side conveyance surface 8b Low speed side suction hole 9a Low speed side conveyance surface 9b High speed side conveyance surface 15 Following electric motor

Claims

In a longitudinal stretching apparatus for stretching a thermoplastic film heated by a heating roll by a peripheral speed difference between a plurality of low-speed driving rolls and a plurality of high-speed driving rolls having a peripheral speed larger than that of the low-speed driving rolls, the plurality of low-speed driving rolls And the plurality of high-speed drive rolls are composed of a suction roll having a plurality of suction holes on the transport surface of the thermoplastic film,
A plurality of heating rolls are provided between the adjacent low-speed drive roll and the high-speed drive roll,
Actuators are provided in the plurality of low-speed drive rolls, the plurality of high-speed drive rolls, and the plurality of heating rolls, respectively, and the plurality of low-speed drive rolls, the plurality of high-speed drive rolls, and the plurality of heating rolls are independent of each other. Is configured to be rotationally driven,
A longitudinal stretching apparatus controlled so that an output torque for each actuator matches a target value set for each actuator.
The actuators are respectively connected to the plurality of low-speed drive rolls, the plurality of high-speed drive rolls, and the plurality of heating rolls via a torque control device,
When the difference between the output torque and the target value is larger than a specified value, the input shaft and the output shaft of the torque control device are maintained so as to maintain the rotational speed of the output shaft of the torque control device connected to the actuator. If the difference between the output torque and the target value is smaller than the specified value, the rotation speed between the input shaft and the output shaft of the torque control device connected to the actuator The longitudinal stretching apparatus according to claim 1, wherein the longitudinal stretching apparatus is configured not to cause a difference.
The longitudinal stretching device according to claim 2, wherein the torque control device is configured by a powder clutch, and a torque transmission amount is controlled based on the target value.
The longitudinal stretching apparatus according to any one of claims 1 to 3, wherein each of the plurality of heating rolls is configured to be independently temperature-controllable.