JP2006015563A - Method and system for detecting rupture of film and tenter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rupture detecting method of a film capable of certainly detecting even the rupture of the film different in form or position, a rupture detector of the film and a tenter equipped with the rupture detecting method of the film. <P>SOLUTION: In the rupture detecting method of the film for detecting the rupture of the film in the tenter for feeding the film in a definite direction by grasping both side edge parts of the film by a group of stretching clips to stretch the film in its lateral direction, the rupture of the film is detected on the basis of the load torque of a stretching clip driving motor for driving one group of the stretching clips. The rupture detector of the film and the tenter are also disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film breakage detection method, a film breakage detection system, and a tenter, and in particular, a film breakage detection method capable of quickly detecting a film breakage inside the tenter, a film breakage detection system used in the film breakage detection method, And a tenter including the film breakage detection system.

  Various types of film breakage detection systems for detecting film breakage in a tenter that stretches in the width direction while conveying the film in a certain direction have been proposed.

  As such a film breakage detection system, for example, a continuous web pass line sent out from the first step is divided into a second step in which the product web is supplied and a third step in which the torn web is supplied. In the web pass line changing device to change between, provided with a tear detection means for optically detecting the tear of the continuous web sent out from the first step, when the tear of the web is detected by the tear detection means, There is one that cuts the web fed from the first step with a cutter and guides it to the third step (Patent Document 1).

  Also, in a device that changes the pass line when the film is torn, a difference in light reflectance is detected by the optical sensor, and the output result of the optical sensor is input to the CPU, and the CPU changes to the pass line changing device. It has been proposed to output a drive signal (Patent Document 2).

Further, a transmission window is provided in the tenter, and an infrared measuring device is provided outside the transmission window to detect the infrared light transmitted through the transmission window, thereby detecting the temperature of the film. At that time, in order to prevent sublimates such as oligomers from depositing on the transmission window from the film, a technique of heating the transmission window above the deposition temperature has also been proposed (Patent Document 3).
JP-A-6-270246 JP-A-6-329311 JP 2002-148118 A

  However, despite the fact that there are various film tear forms and tear occurrence positions in the tenter, the film break detection system detects a film break by a single method, so depending on the form and position of the tear. There was a problem that could not be detected.

  The present invention has been made to solve the above-mentioned problems, and a film breakage detection method that can reliably detect even film tears having different forms and positions, and a film breakage detection apparatus that can be suitably used for the film breakage method And a tenter including the film breakage detection device.

  According to the first aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. The present invention relates to a detection method for detecting a film breakage, wherein the film breakage is detected based on a load torque of a stretch clip drive motor that drives the group of stretch clips.

  When the film is stretched in the tenter, the stretching clip drive motor is responsible for the mechanical loss between the stretching clips, the film transport speed, the tension in the transport direction, and the torque required for stretching in the width direction. The necessary torque is generated. When the film is torn, in most cases, the torque required for stretching in the width direction of the film decreases, so the load torque of the stretching clip drive motor also decreases. Therefore, it is possible to detect the tearing of the film by detecting a decrease in the load torque of the extending clip driving motor.

  In the film breakage detection method, the film breakage can be detected indirectly at a location away from the tenter by detecting a decrease in the load torque of the stretching clip drive motor. Also, since there is no need to place a sensor inside the tenter, when the film is torn inside the tenter, the torn film, etc. physically interferes with the sensor, causing the sensor to be damaged, or a broken film on the sensor. There is no problem of adhesion and malfunction, and film tearing can be measured stably.

  In the film break detection method, it may be determined that a film break has occurred when the load torque decreases and becomes lower than a predetermined threshold value, and the decrease in the load torque continues for a certain time or more. It may be determined that the film has been torn.

  Further, as a method for detecting the load torque of the extending clip driving motor, in addition to the method of obtaining the load torque based on the load current flowing through the extending clip driving motor, the load torque is directly measured by a torque measuring means such as a torque meter. There is a method to measure.

  According to the second aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. A detection method for detecting film breakage, wherein a film breakage is detected by a plurality of infrared sensors arranged along a width direction of the film inside a casing in which the film is conveyed in the tenter. Regarding the method.

  When film breakage detection is performed only by the method of detecting the decrease in the load torque of the stretching clip drive motor, there is a possibility that the film breakage without the decrease in the load torque of the stretching clip drive motor may not be detected. In the method, since an infrared sensor is used in combination to detect film breakage, it is possible to detect film breakage without a decrease in load torque. In addition, since a plurality of the infrared sensors are arranged along the width direction of the film, not only the tear generated in the central portion of the film but also the tear generated in the biting portion of the stretched clip at the side edge portion of the film. Can be reliably detected.

  According to the third aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. The present invention relates to a method for detecting film breakage, wherein the film breakage is detected by an ultrasonic sensor disposed at an exit of a casing in which the film is conveyed in the tenter.

  In the film breakage detection method, the film breakage is detected based on the difference in the ultrasonic wave reception state in the ultrasonic sensor between the case where the film is present and the case where the film is not present. . Furthermore, there is no obstacle caused by sublimation from the film, and the ultrasonic sensor is inexpensive.

  However, many ultrasonic sensors have no heat resistance. However, in the film breakage detection method, the ultrasonic sensor is disposed at the outlet of the casing where the film is conveyed in the tenter. Will not be affected.

  According to a fourth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. In the detection method, film breakage detection based on a load torque of a stretching clip driving motor that drives the group of stretching clips, and an arrangement along the width direction of the film in a casing in which the film is transported by the tenter. Film breakage is detected by a plurality of infrared sensors provided, and if film breakage is detected by at least one of the two film breakage detections, it is determined that film breakage exists. The present invention relates to a tear detection method.

  In the case of detecting film breakage based only on the detection result of the load torque of the stretching clip drive motor, a tenant is displayed while the load torque hardly changes, or the load torque decreases to a preset threshold value. In the case of a tear that reaches the exit, it may not be detected.

  In addition, when an infrared sensor is provided immediately after the stretching zone in the tenter, it is possible to detect tears at the center of the film in the stretching zone and tears at the clip biting portion, but heat fixing / relaxation downstream from the stretching zone. It is not possible to detect film breaks occurring in the zone.

  However, in the film breakage detection method, since the detection of the load torque of the extending clip drive motor and the detection of the reflected infrared ray or the transmitted infrared ray in the infrared sensor are combined, the film breakage that cannot be detected by the load torque measurement is also detected by the infrared sensor. Can be detected reliably. Further, film breakage occurring in the heat fixing / relaxation zone that cannot be detected by the infrared sensor can be easily detected from fluctuations in the load torque of the stretch clip drive motor.

  Thus, according to the film break detection method, almost all film breaks can be detected.

  According to a fifth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. In the detection method, film breakage detection based on a load torque of a stretching clip driving motor that drives the group of stretching clips, and an arrangement along the width direction of the film in a casing in which the film is transported by the tenter. Film breakage detection by a plurality of infrared sensors provided, and film breakage detection by an ultrasonic sensor disposed at an exit of a casing in which the film is transported in the tenter, and at least of these three film detections If a film break is detected by one, determine that a film break exists It relates to a film break detection method according to symptoms.

  Although most film breaks can be detected by detecting film breakage based on the load torque of the stretching clip drive motor and detecting film breakage by an infrared sensor, the film breakage detection method should further use film breakage detection by an ultrasonic sensor. Therefore, it is possible to prevent almost 100% of the broken film from proceeding to the downstream process.

  According to a sixth aspect of the present invention, there is provided the film breakage detecting method according to the first aspect, wherein the film breakage is detected by detecting that the load torque of the stretched clip drive motor has fallen below a predetermined threshold. It relates to a detection method.

  Since the film break detection method determines that the film break has been broken when the load torque falls below a predetermined threshold, the film break can be accurately detected.

  A seventh aspect of the present invention relates to the film breakage detecting method according to the sixth aspect, wherein when the thickness of the film is large, the threshold is set higher than when the thickness is small.

  The load torque of the stretching clip drive motor is large when the film is thick and small when the film is thin. Therefore, if the threshold is determined in accordance with the load torque when the film is thin, film breakage may not be detected when the film is thick. On the other hand, if the threshold value is set in accordance with the load torque when the film is thick, when the film is thin, over-detection in which film breakage is detected even though film breakage does not actually occur may occur.

  However, since the threshold value is set according to the thickness of the film in the film tear detection method, the film tear is reliably detected regardless of whether the film is thin or thick, and excessive detection does not occur.

  The invention according to claim 8 relates to the film break detection method according to claim 7, wherein when the tension applied to the film in the tenter is strong, the threshold is set higher than when the tension is weak.

  In the tenter, the tension applied to the film is not stable immediately after the start of production, and the tension applied to the film varies when the post-process device is operated, such as when the winding core of the winding device is replaced.

  In the film tear detection method, when the tension is strong, the threshold is set higher than when the tension is weak. Therefore, excessive detection occurs due to fluctuations in the tension applied to the film, or film tear is not detected. Is reliably prevented.

  A ninth aspect of the present invention is the film breakage detecting method according to any one of the first, fourth, fifth, and sixth aspects, wherein the load torque is detected based on a load current flowing through the extending clip driving motor. The present invention relates to a film tear detection method.

  In the film breakage detection method, the load torque increases by increasing the load torque of the stretching clip drive motor, and the load current decreases when the load torque decreases. Detected.

  Therefore, a measuring unit for measuring load torque such as a torque meter is unnecessary, and fluctuations in load torque can be detected quickly.

  The invention according to claim 10 is the film break detection method according to claim 2, 4 or 5, wherein the infrared sensor for detecting film break is immediately after the stretching zone for stretching the film in the width direction in the tenter. The present invention relates to a method for detecting film breakage.

  Most film tears occur when the film is stretched in the stretching zone.

  In the film break detection method, since the infrared sensor is provided immediately after the stretching zone, it is possible to reliably detect the film break that has occurred in the stretching zone.

  The invention described in claim 11 relates to the film breakage detection method according to claim 10, wherein the infrared sensor is a reflective infrared sensor that detects infrared light reflected by the film. .

  When a transmissive sensor is used as an infrared sensor, the amount of light reduced by transmission varies depending on the thickness and color of the film. Therefore, in a line for manufacturing a wide variety of stretched films, it varies depending on the thickness and color of the film. It may be necessary to provide an infrared sensor.

  However, in the film breakage detection method, since the reflected light type infrared sensor that detects the infrared light reflected upon the film is used, the light attenuation amount is constant regardless of the thickness and color of the film. . Therefore, the same infrared sensor can be used even if the types of films to be manufactured are different.

  The invention according to claim 12 is the film break detection method according to claim 11, wherein the infrared sensor is set to a temperature higher than the sublimation temperature of the oligomer generated from the film and lower than the heat resistant temperature of the infrared sensor. The present invention relates to a film breakage detection method for detecting film breakage by heating.

  In the tenter, the film is preheated and stretched, and then heated to a higher temperature for heat fixation and heat relaxation. Therefore, when the film is a polyethylene terephthalate resin, oligomers sublimate from the surface and enter the inside of the tenter. Adhere to.

  However, in the film breakage detection method, since the infrared sensor is heated to a temperature higher than the sublimation temperature of the oligomer, the oligomer sublimated from the surface adheres to the infrared sensor, and the amount of light received decreases with time. It is prevented that the tear cannot be detected.

  According to the thirteenth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. A detection system, a load torque detection unit for detecting a load torque of a stretch clip drive motor that drives the group of stretch clips, and whether a film tear has occurred based on a detection result of the load torque in the load torque detection unit The present invention relates to a film breakage detection system comprising a film breakage determination unit for determining whether or not the film breakage is detected.

  The film breakage detection system can be suitably used for carrying out the film breakage detection method according to claim 1.

  Further, in the film break detection system, since the film is also detected by detecting a decrease in the load torque of the stretching clip drive motor, it is necessary to provide a film break detection sensor inside the tenter. Absent. Therefore, the film break detection system has a simple configuration. Moreover, when the film breaks inside the tenter, there is no problem that the torn film etc. physically interferes with the sensor and the sensor breaks, or the film fragments adhere to the sensor and malfunctions. Film tear can be measured stably.

  In the film tear determination unit, it may be determined that the film tear has occurred when the load torque decreases and becomes lower than a predetermined threshold value, and the decrease in the load torque continues for a certain time or more. It may be determined that the film has been torn.

  In the load torque detector, the load torque may be obtained based on the load current flowing through the extending clip drive motor, or the load torque may be directly measured by a torque measuring means such as a torque meter.

  According to the fourteenth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. A detection system comprising: a plurality of infrared sensors disposed along a width direction of the film inside a casing in which the film is conveyed in the tenter; and film breakage based on a light reception result of the infrared sensor The present invention relates to a film breakage detection system including a film breakage determination unit that determines whether or not the film breakage has occurred.

  The film breakage detection system can be suitably used for carrying out the film breakage detection method according to claim 2.

  In the film break detection system, since the film break is detected by the infrared sensor, it is possible to detect the film break without reducing the load torque.

  In addition, since a plurality of infrared sensors are arranged along the width direction of the film, not only the tear generated in the vicinity of the center portion of the film but also the tear generated in the biting portion of the stretched clip can be reliably detected.

  According to the fifteenth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. An ultrasonic sensor disposed at an exit of a casing to which a film is conveyed in the tenter, and a film for determining whether film breakage has occurred based on a reception result of the ultrasonic sensor The present invention relates to a film breakage detection system comprising a breakage determination unit.

  The film breakage detection system can be suitably used for carrying out the film breakage detection method according to claim 3.

  The film breakage detection system is not obstructed by the sublimated material sublimated from the film. Further, since the ultrasonic sensor itself is inexpensive, the film breakage detection system can also be configured at a low cost.

  According to the sixteenth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. A detection system for detecting a load torque of a stretching clip drive motor that drives the group of stretching clips; and a width direction of the film in a casing in which the film is conveyed in the tenter. A plurality of infrared sensors arranged and a film breakage determination unit that determines whether film breakage has occurred based on infrared detection results of the load torque detection unit and the infrared sensor, and the film breakage The determination unit is a film breaker in at least one of the load torque detection unit and the infrared sensor. When issued relates film break detection system characterized in that it is determined that the presence of film tear.

  The film breakage detection system can be suitably used for carrying out the film breakage detection method according to claim 4.

  In the film breakage detection system, since the load torque detection unit and the infrared sensor are used in combination, a partial breakage in which there is almost no change in the load torque or while the load torque is lowered to a preset threshold value. Film breaks that cannot be detected by the load torque detector can be reliably detected by the infrared sensor without significant fluctuations in the load load torque, such as tears that reach the tenter exit.

  Therefore, according to the film break detection system, most film breaks can be detected. That is, the film breakage that cannot be detected by the load torque measurement can be reliably detected by the infrared sensor, and the film breakage occurring in the heat fixing / relaxation zone that cannot be detected by the infrared sensor can be reliably detected by the load torque measurement.

  According to the seventeenth aspect of the present invention, film tearing is detected in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction. A detection system for detecting a load torque of a stretching clip drive motor that drives the group of stretching clips; and a width direction of the film in a casing in which the film is conveyed in the tenter. A plurality of infrared sensors disposed in the tenter, an ultrasonic sensor disposed at an exit of a casing in which the film is conveyed in the tenter, infrared light in the load torque detector, the infrared sensor, and the ultrasonic sensor A film breakage determination unit for determining whether film breakage has occurred based on the detection result of The film determination unit is characterized by determining that film breakage exists when film breakage is detected in at least one of the load torque detection unit, the infrared sensor, and the ultrasonic sensor. .

  The film breakage detection system can be suitably used for carrying out the film breakage detection method according to claim 5.

  According to the film breakage detection system, since the film breakage that has been detected by the infrared sensor and the load torque detector can be detected by the ultrasonic sensor, the film breakage can be detected almost 100% before being sent to the downstream side.

  The invention described in claim 18 is the film break detection system according to claim 13, 16 or 17, wherein the film break determination unit indicates that the load torque of the stretched clip drive motor has fallen below a predetermined threshold. Thus, the present invention relates to a film breakage detection system for detecting film breakage.

  In the film tearing system, it is determined that the film tearing is broken when the load torque falls below a predetermined threshold value, so that the film tearing can be accurately detected.

  The invention according to claim 19 is the film break detection system according to claim 18, wherein, in the film break determination unit, when the thickness of the film is large, the threshold is set higher than when the thickness is small. The present invention relates to a film break detection system.

  In the film break detection system, for the same reason as described in claim 7, it is possible to reliably detect the film break when the film is thick or thin.

  The invention described in claim 20 is the film break detection system according to claim 18 or 19, wherein, in the film break determination unit, when the tension applied to the film in the tenter is strong, than when the tension is weak. The present invention relates to a film breakage detection system in which a threshold is set high.

  According to the film breakage detection system, it is possible to reliably prevent over-detection due to fluctuations in the tension applied to the film or film breakage not being detected.

  The invention according to claim 21 is the film break detection system according to any one of claims 18 to 20, wherein the film break determination unit is configured such that when the tenter is operated in a steady state, the stretched clip Based on a threshold value SV2 determined based on the current value of the load torque of the drive motor, when the tension of the film in the tenter is more than a predetermined magnitude, the threshold value SV1 smaller than the threshold value SV2 is used. The present invention relates to a film breakage detection system that detects film breakage.

  According to the film breakage detection system, when a tenter is operated in a steady state and a subsequent process device such as a winding device is operated to reduce the film tension, this is erroneously detected as a film breakage. Problems are effectively prevented.

  The invention according to claim 22 is the film breakage detection system according to any one of claims 18 to 21, wherein the film breakage determination unit is configured to use the load torque based on a load current flowing through the stretched clip drive motor. The present invention relates to a film breakage detection system for detecting a film.

  In the film breakage detection system, since it is not necessary to add a torque measuring means such as a torque meter in order to detect the load torque, the configuration is simplified.

  The invention described in claim 23 is the film break detection system according to claim 14, 16 or 17, wherein the infrared sensor is provided immediately after a stretching zone for stretching the film in the width direction in the tenter. The present invention relates to a film break detection system.

  In the film breakage detection system, since the infrared sensor is provided immediately after the stretching zone, it is possible to reliably detect the film breakage occurring in the stretching zone.

  The invention described in claim 24 relates to the film breakage detection system according to claim 23, wherein the infrared sensor is a reflective infrared sensor that detects infrared light reflected by the film. .

  When a transmissive sensor is used as an infrared sensor, the amount of light diminished by transmission varies depending on the thickness and color of the film. Therefore, in a line that produces a wide variety of stretched films, detection according to the thickness and color of the film It may be necessary to prepare a plurality of infrared sensors having a wavelength region and sensitivity.

  However, since the film break detection system uses a reflected light type infrared sensor that detects infrared light reflected on the film, the film breaks with the same infrared sensor even if the thickness and color of the film are different. Can be detected, and the system configuration is simplified.

  The invention according to claim 25 is the film break detection method according to claim 24, wherein the infrared sensor is higher than the sublimation temperature of the oligomer generated from the film when the film break is detected, and is higher than the heat resistance temperature of the infrared sensor. Also relates to a film breakage detection system that is heated to a low temperature.

  In the film breakage detection system, since the infrared sensor is heated to a temperature higher than the sublimation temperature of the oligomer, it was generated even when a sublimate such as an oligomer was generated during heat fixation and relaxation treatment of the film. It is prevented that the sublimate adheres to the infrared sensor and the amount of received light decreases with time, making it impossible to detect film breakage.

  A twenty-sixth aspect of the present invention relates to the film breakage detection system according to the fifteenth, sixteenth, or seventeenth aspect, wherein the ultrasonic sensor is provided in a plurality along the width direction of the film. .

  In the film breakage detection system, not only the breakage occurring at the center of the film but also the breakage occurring near the stretched clip biting part can be detected.

  The invention according to claim 27 is a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction, and detects the tearing of the film A tenter comprising the film break detection system according to any one of claims 13 to 26.

  In the tenter, any film breakage occurring in any of the stretching zone, the heat fixing / relaxation zone, and the cooling zone can be detected in the case where the film is transported in the tenter or near the outlet. It is effectively prevented that the film that has been torn inside is sent to the post-process and the post-process apparatus is damaged, a production loss occurs, or an unsteady restoration operation occurs.

  As described above, according to the present invention, a film breakage detection method, a film breakage detection system, and a tenter including the film breakage detection system that can reliably detect even film breaks of different forms and positions are provided. .

1. Embodiment 1
An example of a biaxially stretched film production line having a tenter according to the present invention will be described below.

  As shown in FIGS. 1 and 2, the biaxially stretched film production line 100 according to Embodiment 1 is a raw film production for producing a raw film from the upstream side to the downstream side along the film conveyance direction. Part 6, a longitudinally stretched part 4 that stretches the raw film F manufactured in the raw film production part 6 in the longitudinal direction, and a stretched raw film F that is stretched in the longitudinal direction in the longitudinally stretched part 4 A tenter 2 to be wound and a winding portion 8 for winding a biaxially stretched film f obtained by stretching in the width direction with the tenter 2 are disposed.

  The raw film production unit 6 includes a slit-shaped die 62 from which a raw material resin such as polyethylene terephthalate (PET) resin is extruded in a film shape, and a cooling drum 64 that cools the film of the raw material resin extruded by the die 62. .

  The longitudinally stretched portion 4 is provided with a group of rollers 42 around which the raw film F is wound at a predetermined wrap angle.

  The roller 42 includes a preheating roller 42a that preheats the film F from the inlet toward the outlet, a stretching roller 42b that stretches the raw film F preheated by the preheating roller 42a in the longitudinal direction, and a raw film that is stretched by the stretching roller 42b. It is divided into a cooling roller 42c for cooling the anti-film F. In the stretching roller 42b, the introduced film F is stretched in the longitudinal direction by making the rotational speed of the exit-side stretching roller 42b larger than the rotational speed of the entrance-side stretching roller 42b.

  As shown in FIG. 3, the tenter 2 includes a housing 20 and a pair of clip extending devices 22 provided in the housing 20 along the both side walls substantially over the entire length of the housing 20. .

  The clip stretching device 22 includes a group of stretching clips 22A, a loop-shaped driving chain 22B to which the stretching clips 22A are attached, and stretching for moving the stretching clips along the transport direction a of the film F by rotating the driving chain 22B. Clip drive motor 22C. The clip stretching device 22 is further provided with a clip closing member (not shown) for closing the stretching clip 22A on the inlet side, and a clip opening member (not shown) for opening the stretching clip 22A on the outlet side. ing.

  The tenter 2 is divided into a preheating zone 2A, a stretching zone 2B, a heat setting zone 2C, a heat relaxation zone 2D, a neutral zone 2E, and a cooling zone 2F from the inlet toward the outlet. The clip stretching device 22 is bent outward in the stretching zone 2B, but is provided parallel to each other in the other zones.

  The preheating zone 2A and the stretching zone 2B are heated to the stretching temperature, and the heat setting zone 2C and the thermal relaxation zone 2D are heated to a temperature higher than the stretching temperature. Therefore, since the temperature difference between the thermal relaxation zone 2D and the cooling zone 2F is large, a neutral zone 2E is provided between them to relax the temperature difference between the two.

  In the preheating zone 2A, the introduced film F is preheated, and at the same time, both side edges of the film F are gripped by the extending clips 22A. The film F preheated in the preheating zone 2A is introduced into the stretching zone 2B and is stretched by being stretched outward along the width direction by the stretching clip 22A. The film F is stretched along the width direction in the stretching zone 2B, and then introduced into the heat setting zone 2C to heat-set the stretched structure. And the annealing process is performed in the thermal relaxation zone 2D, and the stress remaining inside the film F is relaxed. The film F that has passed through the thermal relaxation zone 2D passes through the neutral zone 2E, is cooled to a predetermined temperature in the cooling zone 2F, and is led out from the tenter 2.

  Three infrared sensors 24 are provided along the width direction of the film F immediately after the stretching zone 2 </ b> B inside the housing 20. An ultrasonic sensor 26 is provided at the exit of the tenter 2 so as to sandwich the film F conveyance path from above and below. Three sets of ultrasonic sensors 26 are also provided along the width direction of the film F.

  Each of the infrared sensors 24 is a reflection type infrared sensor, and is higher than the sublimation temperature of the sublimate so that the sublimate such as an oligomer generated by heating the film F in the stretching zone 2B does not adhere to the infrared sensor 24 itself. It is heated to a temperature lower than the heat resistance temperature. Therefore, film breakage can be stably detected regardless of the thickness or color of the film F. For example, in the case of a reflective infrared sensor having a light receiving element and a light emitting element, outputting infrared light from the light emitting element, and receiving light reflected from the film F by the light receiving element, the infrared light when the film F is present Film breakage can be detected from the difference between the amount of reflected light and the amount of infrared light reflected when there is no film F.

  The tenter 2 is further provided with a load current measuring unit 25 that measures the load current of the extending clip drive motor 22C. When the film F is torn and the load torque of the stretching clip drive motor 22C is decreased, the load current is also decreased. Therefore, the load current measuring unit 25 can detect the film current by detecting the decrease in the load current. In FIG. 3, reference numeral 28 denotes an inverter that drives the extending clip drive motor 22C.

  A laser cutter 10 for cutting the film F with a laser beam is provided between the longitudinally stretched portion 4 and the tenter 2, and a cutter for cutting the film F with a cutting blade between the tenter 2 and the winding portion 8. 12 is provided. Below the laser cutter 10, a pulverization processing device 14 that pulverizes the film upstream of the portion cut by the laser cutter 10, and a first transfer path of the film F that has passed through the laser cutter 10 toward the tenter 2. And a film path switching unit 15 for switching to either the second path toward the pulverizing apparatus 14. On the other hand, below the cutter 12, a pulverization processing device 16 that pulverizes the film F on the upstream side of the portion cut by the cutter 12, and a transport path of the film F that has passed through the cutter 12 go to the winding unit 8. A film path switching unit 17 that switches to either the first path or the second path toward the pulverization processing device 16 is provided.

In the tenter 2, as shown by A and C in FIG. 4, the center of the film F is broken, or as shown by B, the stretched clip biting portion in which the stretched clip 22A is bitten is broken in the film F. There are things to do. Therefore, if the form of film breakage and the location of occurrence of film tears in the tenter 2 are roughly summarized,
Type a. Tearing of the film center that occurred in the stretching zone 2B,
Type b. Tearing of the clip biting portion generated in the stretching zone 2B,
Type c. Tearing of the center of the film caused in the heat setting zone 2C or the heat relaxation zone 2D,
Type d. Breaking of the clip biting portion generated in the heat setting zone 2C or the heat relaxation zone 2D,
Type e. Tearing of the film center that occurred in the cooling zone 2F,
Type f. Tearing of the clip biting portion generated in the cooling zone 2F,
The 6 types are summarized.

  Of the six types of film breakage, the break accompanied by a decrease in load torque is detected by the load current measuring unit 25 regardless of the occurrence location.

  On the other hand, the load current is not detected by the load current measuring unit 25 without breaking the load torque, specifically, only the film center portion or the clip biting portion is only partially broken. However, even if such a tear occurs, what is generated in the stretching zone 2B, such as a film tear A or a film tear B, is detected by the infrared sensor 24. In addition, film breakage that occurs in the heat setting zone 2C or downstream thereof, such as film breakage C to film breakage F, is detected by the ultrasonic sensor 26.

  In addition, in the infrared sensor 24 and the ultrasonic sensor 26, the tear generated at the center of the film as in types a, c, and e is detected by a sensor located at the center, and the film as in types b, d, and f. The tear generated in the clip biting portion is detected by one of the sensors located at both ends. Therefore, the position of the film break can be specified by the position of the sensor at which the break is detected.

  When at least one of the load current measuring unit 25 and the infrared sensor 24 detects film breakage, the cutter 12 operates to cut the film F downstream of the tenter 2. Then, the portion of the film F where the film is broken is guided to the crushing processing device 16 by the film path switching unit 17 to be crushed and reused.

  On the other hand, when neither the load current measuring unit 25 nor the infrared sensor 24 detects film breakage and the film break is detected for the first time by the ultrasonic sensor 26, there is no time for operating the cutter 12. The cutter 10 is operated to cut the film F on the upstream side of the tenter 2. A portion of the film F on the downstream side of the cut portion passes through the tenter 2 and is sent to the winding portion 8. On the other hand, the portion upstream of the cut portion of the film F is guided to the pulverization processing device 14 by the film path switching portion 15 to be crushed and reused.

  Hereinafter, the principle and procedure for detecting film breakage by the load current measuring unit 25 will be described in detail.

  As shown in FIGS. 5A to 5C, when the thickness of the film F is large, the load current detected by the load current measuring unit 25 is also large, and when the thickness of the film F is small, the load current measuring unit 25 detects it. Load current is small. And as shown to the area | region a, immediately after manufacture start, load current also falls with time. Further, as shown in the region b, the value of the load current also varies when the post-process device operates as in the case where the winding core is replaced in the winding unit 8. Here, as described above, since the load current and the load torque are directly proportional to each other, the load current does not fluctuate but is also the load torque.

  As shown in FIG. 6, in both cases where the thickness of the film F is large and small, when the film breaks, the load current decreases toward the respective current lower limit values and is stabilized at the current lower limit value. On the other hand, when the post-process apparatus is operated, the load current instantaneously decreases or increases as shown in region b in FIG. 5, but immediately returns to the original value. Also, as shown in FIG. 7, the load current itself is usually not dependent on the thickness of the film, and when the film breakage occurs, it is far more than when the winding unit 8 is started or stopped. Small.

  Therefore, as shown in FIG. 7, when the thickness of the film F is large, medium, and small, the load current threshold is set smaller than the fluctuation range of the load current during steady operation, and the film By determining a value larger than the load current value when the tear occurs, and determining that a film break has occurred inside the tenter 2 when the load current measuring unit 25 detects a load current smaller than the threshold value, Film tear can be detected.

  Further, as shown in FIG. 8 (A), when the post-process equipment such as the winding unit 8 is operated, the load current suddenly decreases once, but immediately returns to the original steady state current value. On the other hand, when film breakage occurs in the tenter 2, the load current monotonously decreases toward the current lower limit value as shown in FIG.

  Therefore, even when the load current value decreases, it is determined that the film F is not torn when a pattern as shown in FIG. 8A is drawn, and as shown in FIG. It is effective to mistakenly detect a change in load current when a post-process facility is operated as a change in load current due to film breakage by determining that the film F has been broken only when a simple pattern is drawn. Can be prevented.

  In addition, as shown in FIG. 9, two threshold values, a threshold value SV2 during steady operation and a threshold value SV1 during operation of the post-process apparatus may be set. Here, since the fluctuation of the load current becomes larger during the post-process apparatus operation than during the steady operation, the threshold value SV1 is set to a value lower than the threshold value SV2. When the trigger signal for starting the operation is input to the post-process device, the threshold value is automatically changed from SV2 to SV1, and when the trigger signal for stopping the operation is input to the post-process device, a plurality of samples of the load current are input. The threshold value is automatically changed from SV1 to SV2 at the time t (second) when the average value (for example, the average value of 10 points) returns to the value during steady operation. In FIG. 9, PV is a measured value of the load current, and PVAv is a value obtained by measuring a specific number of points, for example, 10 points PV during a specific measurement time, for example, 1 to 2 seconds, and averaging them.

  Even with such a method, it is possible to effectively prevent a change in the load current when operating the post-process equipment from being erroneously detected as a change in the load current due to film breakage.

  In the biaxially stretched film production line 100 according to Embodiment 1, film breakage at the tenter 2 is usually detected as a decrease in load current in the stretched clip drive motor 22C. Further, even if the film breakage is not accompanied by a decrease in the load current in the extending clip drive motor 22C, it is usually detected by the infrared sensor 24.

  Therefore, it is possible to prevent the portion where the film breakage has occurred from being sent to the winding unit by operating the cutter 12 before the breakage occurring in the film F reaches the winding unit 8.

  Since the film breakage detecting means is further provided with an ultrasonic sensor 26, even if the film breakage is not detected by the infrared sensor 24 and the load current measuring unit 25, it is prevented from being sent to the winding unit 8. The

  The film breakage detection method of the present invention includes a biaxially stretched polyethylene resin film, a biaxially stretched polypropylene resin film, a biaxially stretched ethylene / propylene copolymer resin film, a biaxially stretched polyvinyl chloride resin film, and a biaxially stretched polystyrene resin film. The present invention can be applied to tenters used for producing various biaxially stretched films such as a biaxially stretched polyethylene terephthalate resin film.

FIG. 1 is a schematic diagram illustrating a configuration up to a tenter in a biaxially stretched film production line according to Embodiment 1. FIG. FIG. 1 is a schematic diagram illustrating a configuration downstream of a tenter in a biaxially stretched film production line according to Embodiment 1. FIG. 3 is a perspective view showing a configuration of a tenter provided in the biaxially stretched film production line shown in FIG. FIG. 4 is a perspective view showing a form of film breakage that may occur in the tenter shown in FIG. FIG. 5 is a graph showing the relationship between the film thickness during steady operation and the change over time of the load current flowing through the stretching clip drive motor provided in the tenter shown in FIG. FIG. 6 is a graph showing the change over time of the load current flowing through the stretching clip drive motor when film breakage occurs when the film is thick and when the film is thin. FIG. 7 is a graph showing the relationship between the fluctuation range of the load current, the threshold value, and the load current flowing through the stretched clip drive motor when film breakage occurs when the film thickness is thick, medium, and thin. It is. FIG. 8 is a graph showing the change over time of the load current flowing through the stretched clip drive motor when the post-process apparatus is operated and when a film tear occurs. FIG. 9 is a graph showing an example in which the threshold value for determining film defects is changed between when the operation of the post-process apparatus is started and when the operation is stopped.

Explanation of symbols

2 Tenta 2A Preheating zone 2B Stretching zone 2C Thermal fixing zone 2D Thermal relaxation zone 2E Neutral zone 2F Cooling zone 4 Longitudinal stretching section 6 Original film production section 8 Winding section 20 Housing 22 Clip stretching apparatus 22A Stretching clip 22B Drive chain 22C Stretched clip drive motor 24 Infrared sensor 25 Load current measuring unit 26 Ultrasonic sensor 100 Biaxially stretched film production line

Claims (27)

A film tear detection method for detecting tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A film tear detection method, comprising: detecting a film tear based on a change in a load torque of a stretch clip drive motor that drives the group of stretch clips. A film tear detection method for detecting tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A film breakage detection method, comprising: detecting a film breakage by a plurality of infrared sensors arranged along a width direction of the film inside a casing in which the film is conveyed in the tenter. A film tear detection method for detecting tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A film breakage detection method, comprising: detecting a film breakage by an ultrasonic sensor disposed at an exit of a casing in which the film is conveyed in the tenter. A film tear detection method for detecting tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
Detection of film breakage based on a load torque of a stretching clip driving motor that drives the group of stretching clips, and a plurality of infrared rays arranged along the width direction of the film inside a casing in which the film is conveyed in the tenter The film breakage is detected by the sensor,
A film breakage detection method, wherein if a film breakage is detected by at least one of the two film breakage detections, it is determined that a film breakage exists. A film tear detection method for detecting tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
Detection of film breakage based on a load torque of a stretching clip driving motor that drives the group of stretching clips, and a plurality of infrared rays arranged along the width direction of the film inside a casing in which the film is conveyed in the tenter Film tear detection by the sensor and film tear detection by the ultrasonic sensor disposed at the exit of the casing where the film is transported in the tenter,
A film breakage detection method comprising: determining that a film breakage is present when a film breakage is detected by at least one of the three film breakage detections.   The film breakage detection method according to claim 1, 4 or 5, wherein the film breakage is detected when a load torque of the stretching clip drive motor falls below a predetermined threshold.   The film breakage detection method according to claim 6, wherein when the thickness of the film is large, the threshold is set higher than when the thickness is small.   The film breakage detection method according to claim 7, wherein when the tension in the transport direction applied to the film in the tenter is high, the threshold is set higher than when the tension is weak.   The film breakage detection method according to any one of claims 1, 4, 5, 6, 7, and 8, wherein the load torque is detected based on a load current flowing through the stretching clip drive motor.   6. The film break detection method according to claim 2, wherein the infrared sensor for detecting film breakage is provided immediately after a stretching zone for stretching the film in the width direction in the tenter.   The film breakage detection method according to claim 10, wherein the infrared sensor is a reflective infrared sensor that detects infrared light that is reflected by the film.   The film breakage detection method according to claim 11, wherein the film breakage is detected by heating the infrared sensor to a temperature higher than a sublimation temperature of an oligomer generated from the film and lower than a heat resistant temperature of the infrared sensor. A film breakage detection system that detects tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A load torque detecting unit for detecting a load torque of an extending clip driving motor for driving the group of extending clips;
A film breakage detection system comprising: a film breakage determination unit that determines whether film breakage has occurred based on a detection result of load torque in the load torque detection unit. A film breakage detection system that detects tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A plurality of infrared sensors arranged along the width direction of the film inside the casing in which the film is conveyed in the tenter;
A film breakage detection system comprising: a film breakage determination unit that determines whether film breakage has occurred based on a light reception result in the infrared sensor. A film breakage detection system that detects tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
An ultrasonic sensor disposed at an outlet of a casing in which a film is conveyed in the tenter;
A film breakage detection system comprising: a film breakage determination unit that determines whether film breakage has occurred based on a reception result in the ultrasonic sensor. A film breakage detection system that detects tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A load torque detecting unit for detecting a load torque of an extending clip driving motor for driving the group of extending clips;
A plurality of infrared sensors arranged along the width direction of the film inside the casing in which the film is conveyed in the tenter;
A film break determination unit that determines whether a film break has occurred based on detection results in the load torque detection unit and the infrared sensor;
The film breakage determination unit determines that a film breakage exists when at least one of the load torque detection unit and the infrared sensor detects a film breakage. A film breakage detection system that detects tearing of the film in a tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretched clips and transporting the film in a certain direction,
A load torque detecting unit for detecting a load torque of an extending clip driving motor for driving the group of extending clips;
A plurality of infrared sensors arranged along the width direction of the film inside the casing in which the film is conveyed in the tenter;
An ultrasonic sensor disposed at an outlet of a casing in which a film is conveyed in the tenter;
A film breakage determination unit that determines whether film breakage has occurred based on detection results in the load torque detection unit, the infrared sensor, and the ultrasonic sensor;
The film breakage determination unit determines that film breakage exists when film breakage is detected in at least one of the load torque detection unit, the infrared sensor, and the ultrasonic sensor. system.   18. The film tear determination unit according to claim 13, 16 or 17, wherein the film tear determination unit detects a film break when the load torque of the extending clip drive motor detected by the load torque detection unit falls below a predetermined threshold. Film tear detection system.   19. The film breakage detection system according to claim 18, wherein the film breakage determination unit sets the threshold value higher when the film thickness is larger than when the film thickness is small.   The film breakage detection system according to claim 18 or 19, wherein in the film breakage determination unit, when the tension in the transport direction applied to the film in the tenter is strong, the threshold is set higher than when the tension is weak.   In the film tear determination unit, when the tenter is operating in a steady state, the film tension in the tenter is determined based on a threshold value SV2 determined based on the current value of the load torque of the stretching clip drive motor. The film breakage detection system according to any one of claims 18 to 20, wherein a film breakage is detected based on a predetermined threshold value SV1 that is smaller than the threshold value SV2 when there is a variation that is greater than or equal to.   The film breakage detection system according to any one of claims 18 to 21, wherein the load torque detection unit detects the load torque based on a load current flowing through the stretching clip drive motor.   The film breakage detection system according to claim 14, 16, or 17, wherein the infrared sensor is provided immediately after a stretching zone for stretching the film in the width direction in the tenter.   The film breakage detection system according to claim 23, wherein the infrared sensor is a reflective infrared sensor that detects infrared light reflected by the film and reflected.   25. The film break detection method according to claim 24, wherein the infrared sensor is heated to a temperature higher than a sublimation temperature of an oligomer generated from the film and lower than a heat resistant temperature of the infrared sensor when a film break is detected.   The film breakage detection system according to claim 15, 16 or 17, wherein a plurality of the ultrasonic sensors are provided along a width direction of the film. A tenter that stretches the film in the width direction by gripping both side edges of the film with a group of stretching clips and transporting the film in a certain direction,
A tenter comprising the film break detection system according to any one of claims 13 to 26, wherein the film break is detected.

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