JPH0662235B2 - Film take-up device - Google Patents

Description

Detailed Description of the Invention

[Industrial applications]

The present invention relates to a film take-up device for taking out a strip-shaped sheet of a drawn film, which is sent out from a lateral (width direction) drawing device in a film forming process.

[Prior art]

Usually, in the film forming step, the belt-shaped unstretched film material is stretched in the longitudinal direction (longitudinal stretching) while traveling between a plurality of rollers provided in the longitudinal stretching device and having different rotational speeds, and then the lateral stretching device. In the above, both edges are grasped by the clips which are opposed to each other and are spaced apart from each other, and are stretched (transversely stretched) in the width direction to form a biaxially stretched film. Further, the uniaxially stretched film may be produced by omitting the longitudinal and transverse stretching devices and installing only the transverse stretching device. In addition, some of the horizontal stretching devices are also known that perform horizontal stretching while widening the interval between adjacent clips to perform horizontal stretching as well as vertical stretching (for example, utility model application publication in 1965). (See Japanese Patent No. 26316). And, in the take-up device connected to the transverse stretching device which is the premise of the present invention, a system is adopted in which the take-up roller is forcibly rotationally driven so that the line speed of the transverse stretching device is almost the same as the line speed. However, the take-up tension of the film was not specifically controlled. That is, in general, a transverse stretching device is provided with a pair of clips at predetermined intervals in the advancing direction of the material on both sides of a strip-shaped synthetic resin material to be stretched, and grips both edges of the material. While the clips are separated in the lateral direction, the material is driven in the direction of travel of the material at a predetermined line speed to horizontally stretch the material into a film of a predetermined thickness, and the horizontally stretched film is taken up by a take-up roller and wound. Although it is wound around the winding shaft as a raw roll by the device, in the conventional transverse stretching device, the take-up roller was driven so as to be interlocked at the same speed as the film feeding speed of the transverse stretching device. .

[Problems to be Solved by the Invention]

However, since the conventional take-up roller is only forcibly driven at the same speed as the line speed of the transverse stretching device as described above, the adjustment for uniform stretching of the film is performed on the take-up device side. It was not controlled by the function of (particularly by tension), and a sufficiently satisfactory result was not always obtained. In addition, for the defects of the winding roll that occurred in the winding process of the raw material following the drawing process and the divided winding process that becomes the product, measures can be taken by adjusting the winding device and split winding device, respectively. It has been taken, but after all, it was not always possible to obtain a satisfactory result. That is, when a laterally stretched film is wound by an in-line winder that is a winding device, a partial wrinkle is generated in the raw fabric winding roll, or if the straightness of the winding roll is significantly impaired, it is continued. Although it sometimes deformed into a drum shape or a drum shape, the defect was not always eliminated by adjusting the winding device. Furthermore, when the film is slit into a narrow width and rewound during the split winding process, not only the wrinkles left on the original roll cannot be removed, but also the film laterally shifts or the split winding roll becomes tapered. However, the problem could not be solved by adjusting the split winding device. The inventor of the present application, in the transverse stretching step, the take-up tension during the stretching has a great influence on the quality of the product, and the above-mentioned defects and problems are caused by improper take-up tension in the transverse stretching step. The present invention has been found out and made the present invention. That is, the film being laterally stretched in the lateral stretching device is easily deformed by heating, but since both edges of the film are gripped and constrained by the clips, the interval between adjacent clips in the traveling direction is If it does not change during the process, the vertical stretching ratio of the film near both edges does not change during horizontal stretching (or, if it is of the type that performs vertical stretching at the same time, the vertical length depends on the change in clip interval). Undergo stretching). On the other hand, the vicinity of the center of the film in the width direction is not directly affected by the restraint by the clip, and therefore the longitudinal stretching ratio thereof may be changed by the influence of the take-up tension. When the take-up tension of the film by the take-up roller is excessive, the central portion of the film in the transverse stretching device is stretched in the longitudinal direction, so that the longitudinal stretching ratio becomes larger than the longitudinal stretching ratios at both edges (second Figure). On the contrary, if the take-up tension by the take-up roller is too small,
As a result of the central portion of the film in the transverse stretching apparatus contracting in the longitudinal direction, the longitudinal stretching ratio becomes smaller than the longitudinal stretching ratio at both edges (Fig. 3). Incidentally, it is generally known that the film-shaped synthetic resin material has a tendency to shrink by generating shrinkage force as well as producing plasticity by heating, and the stretching and shrinkage are the shrinkage force and the take-up tension. It is thought to be caused by the imbalance of the. The transversely stretched film is cooled and the plastic deformation received in the transverse stretching device is fixed. Further, the pulling tension applied by the pulling roller is transmitted to the film in the lateral stretching device by elastic deformation of the film downstream of the lateral stretching device. The distance between the transverse stretching device and the take-up roller is the same at both edges and the central portion of the film, so if there is a difference in the longitudinal stretching ratio in the width direction of the film exiting the transverse stretching device, the relative stretching The part with a low longitudinal stretching ratio (that is, the part with a short original length) undergoes greater elastic deformation than the part with a high longitudinal ratio (that is, the part with a long original length), resulting in an apparent width that is wider. Elastically stretched to be the same in the direction. And, this causes a non-uniform tension in the film width direction, but unless extreme non-uniformity occurs, even when the running film is observed, the film does not have any particular defects such as wrinkles. Appears to be taken evenly. However, in the original web winding process using the in-line winder that follows the drawing process, since the film is usually wound with a lower tension than the drawing process, even a film that looks uniform in the drawing process is elastically deformed due to the low tension. As a result of mitigation,
The above difference in the longitudinal stretching ratio of the film is surfaced, and defects such as local wrinkling and the like appear on the raw fabric winding roll. Further, the hardness of the winding roll becomes non-uniform in the width direction due to the non-uniform tension in the film width direction. In an extreme case, the straightness of the original web winding roll may be impaired, and the roll may be deformed into a claw type (when the take-up tension is low) or a drum shape (when the take-up tension is high). Furthermore, even if this defect is negligible when wound on a roll, it becomes more noticeable when the film slit into a narrow width is rewound in the subsequent split winding process. Can be a problem for the first time. That is, when such an original film is slit into a plurality of narrow films, the narrow film has different longitudinal stretching ratios depending on which part of the original film is slit. Further, even in the same film, the longitudinal stretching ratios are continuously different in the width direction, and the original length on one side of the film is longer than the original length on the other side. This tendency is particularly remarkable in the film slit from a position close to the side edge portion of the original film, but when such a narrow film is rewound with a low tension, the film is wound to the side with a shorter original length during winding. Since it will be displaced and rewinding will be extremely difficult, there will be a problem that extra time and labor are required for the work. In addition, the winding shape of the roll may be displaced in the axial direction, or the tape may be tapered due to uneven tension, resulting in a loss of product value. Furthermore, if it is attempted to remove the wrinkled part or to remove the film side edge part where the change in the longitudinal stretching ratio is relatively large in order to avoid the above problems, the trimming width of the film is usually necessary for removing the clip marks, etc. However, the problem is that a large amount of material is wasted and the yield is reduced. The above problems have become more prominent with the recent thinning of films. In other words, recently, ultra-thin films with a thickness of 10 to several microns have come to be manufactured.However, such ultra-thin films are sensitive to a slight tension difference and expand and contract, so that the entire width is uniform. It became even more difficult to stretch it, and the yield was worse. And, such defects are not in the process of being collected, and may become apparent only in a later step, and the investigation of the cause thereof has been delayed, but as described above, the present inventor, for the first time, the cause is The inventors have found that the take-up tension in the transverse stretching step is inadequate and have completed the present invention.

[Object of the Invention]

An object of the present invention is to solve the above problems,
Therefore, it is an object of the present invention to provide a take-up device that can always keep the take-up tension of the film at an appropriate value in the transverse stretching step. In addition, the transverse stretching apparatus which is the object of the present invention includes a transverse stretching apparatus that simultaneously performs longitudinal stretching (biaxial simultaneous stretching) as described above.

[Means for solving problems]

This invention provides an adjustable dancer roll between the transverse stretching device and the take-up roller in the transverse stretching process so that the take-up tension of the film is always kept at an appropriate value and held, and the displacement detector detects the displacement of the dancer roll. Is detected, and the detection signal is fed back to the speed control device that controls the rotation speed of the take-up roller, and the speed of the take-up roller is controlled so that the position of the dancer roll becomes the reference position. It has the constituent features as described in the claims. In the transverse stretching step, the change in tension greatly affects the quality of the film as a change in the longitudinal stretching rate as described above, and particularly in the case of an ultrathin film, it is remarkable, so that a change in the take-up tension occurs. Needs to eliminate tension fluctuations promptly. The position of the dancer roll is determined by the balance between the set pressing force and the tension of the film, and when the tension of the film decreases, the dancer roll descends to lengthen the traveling path of the film. When the tension of the film is increased and the tension is automatically increased, and when the tension is increased, the dancer roll is raised to shorten the length of the traveling path of the film and the tension of the film is relaxed to automatically increase the tension. It has the function of lowering and restoring to the set tension, so it is the most suitable for such tension adjustment. The dancer roll uses a structure in which the seat path angle does not change at all with respect to the dancer roll displacement, or a structure in which the seat path angle does not change with respect to the dancer roll displacement, as compared with the structure in which the tension changes. It is preferable. The present invention detects the position of the dancer roll and controls the speed of the take-up roller so that the position becomes the reference position. Both of the take-up tensions can be accurately and separately controlled simultaneously.

[Action]

Adjusting the pressing force adjustment unit changes the setting value of the biasing mechanism,
The set pressure of the dancer roll changes. As a result, it is possible to change the tension applied to the film drawn from the film unloading side of the transverse stretching device, and the appropriate take-up tension according to the drawing conditions such as the material and thickness of the drawn film ... Along the width direction of the delivery film, As a result, it becomes easy to apply a uniform tension to the take-up film, which tension is compatible with the film tension capable of forming a film having a uniform elongation and film thickness in the longitudinal direction. Further, during stretching, even if defects such as local wrinkles and slacks appearing on the film as described above, the pulling tension is immediately adjusted by the adjustment of the pressing force adjusting section, and the stretched state of the film without the stretching device is adjusted. Improvements can be addressed to eliminate or reduce defects. The present invention is characterized in that the take-up tension of the stretched film can be adjusted stably and accurately to an appropriate value according to the stretching conditions of the film.

【Example】

Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but each member constituting the device of the present embodiment may be arbitrarily modified in design within the technical level in the field at the time of application of the present invention. Since there are possible parts, the gist of the present invention should not be limited and understood only on the basis of the constitutional conditions of the present embodiment without showing a particular reason. FIG. 1 shows a schematic configuration of a preferred embodiment of the device of the present invention. In the figure, T is a film transverse stretching device, and the film material supplied to the transverse stretching device T is at predetermined intervals. Both edges of the clip _Tc are grasped by the arranged clip _Tc (see FIGS. 2 and 3), drawn into a film having a required width and thickness, and continuously stretched from the transverse stretching device T as a wide strip S. Sent out. Belt-like sheet S fed from the transverse stretching apparatus T certainly it is pulled pinched between the take-up roller 1 and the nip roller 1 'which is rotated by the driving motor M _1. Two guide rollers 2 are provided along the strip-shaped sheet S connected between the lateral stretching device T, the take-up roller 1, and the nip roller 1 '.
2 are provided in parallel and are placed on the sheet S between the two guide rollers 2 and 2 to form a substantially U-shaped sheet traveling path, and the sheet S is guided and displaced vertically due to the tension variation of the sheet S. A dancer roll 9 is provided. In this embodiment, when the dancer roll 9 moves downward, the length of the belt-shaped sheet traveling path between the two guide rollers 2 increases, and when the dancer roll 9 moves upward, the length of the sheet traveling path decreases. It is provided to do so. The dancer roll 9 is provided with a pulling force by an urging mechanism (a pneumatic actuator in this embodiment) 10 and a pulling down force by gravity. The dancer roll 9 tries to move downward by the force (weight) obtained by subtracting the pulling force given by the urging mechanism 10 from the pulling down force due to its own gravity, but the force is the band shape that holds the roll 9. The tension and balance of the seat S are balanced. This downward force is the pressing force of the dancer roll 9, which is a force in the direction of increasing the length of the sheet traveling path, and is also a force that changes the magnitude of the tension applied to the belt-shaped sheet S. . The magnitude of the pressing force of the dancer roll 9 is changed by changing the magnitude of the driving force (pulling force) of the biasing mechanism 10, and the magnitude of the driving force of the biasing mechanism 10 is determined by the pressing force adjusting unit (this embodiment). In the example, it can be changed by adjusting the pressure regulating valve) 10 '. That is, the magnitude of the pressing force of the dancer roll 9 and the tension of the belt-shaped sheet S can be easily adjusted to appropriate values by adjusting the pressing force adjusting unit 10 '. On the other hand, the displacement of the dancer roll 9 from the reference position is detected by a displacement detecting device 11 such as a rotary or direct acting potentiometer or a differential transformer, and the signal thus detected is used for driving the take-up roller 1. It is sent to the speed controller 8 of the motor M ₁ . The speed control device 8 compares the detection signal sent from the displacement detection device 11 of the dancer roll 9 with the set reference signal to immediately return the dancer roll 9 to the reference position when the dancer roll 9 dies. Signal for receiving the line signal from the line speed detection device 5 of the stretching device T, and correcting and further amplifying the signal for returning the dancer roll 9 to the reference position according to the line speed signal. Then, it is sent to the drive motor M ₁ to control its rotation speed. That is, the speed control device 8 increases the rotation speed of the take-up roller 1 when the dancer roll 9 is lower than the reference position, and decreases the rotation speed of the take-up roller 1 when the dancer roll 9 is higher than the reference position. When the rotation speed of the take-up roller 1 increases, the transverse stretching device T
From the amount of the strip-shaped sheet S sent from
Since the amount of the above-mentioned sheet to be taken up is increased, the length of the traveling path of the belt-like sheet S is shortened, whereby the dancer roll 9 is pulled up toward the reference position. Further, when the rotation speed of the take-up roller 1 decreases, the amount of the belt-shaped sheet S sent out from the lateral stretching device T becomes larger than the amount taken by the take-up roller 1, so that the length of the traveling path of the sheet S becomes longer. , By which the dancer roll 9 is pulled down in the direction of the reference position. Thus, the dancer roll 9 is in a floating state within the allowable range so as to always hold the reference position by controlling the rotation speed of the take-up roller 1 by the speed control device 8. In the dancer roll 9 in the floating state, the pressing force (weight) and the pulling force by the tension of the belt-shaped sheet S are in a balanced state. Therefore, in this embodiment, the tension of the sheet S is that of the dancer roll 9. A half of the pressing force is given. Therefore, by operating the pressure adjusting portion (pressure adjusting valve) 10 'to change the pressing force of the dancer roll 9, the magnitude of the pulling tension generated on the belt-shaped sheet S can be adjusted to an appropriate value and delicately. it can. As a result, an appropriate take-up tension is always applied to the film being transversely stretched by the transverse stretching device, and a longitudinally stretched ratio in the width direction is almost uniform, and a defect-free sheet can be delivered and pulled. . The appropriate value of the take-up tension of the strip-shaped sheet S is, for example, orthogonal to the width direction of the film material on the side of being fed into the lateral stretching device for the film, and even after the film is laterally stretched by drawing a straight line in advance. , The goal is to maintain a state that is as close to a straight line as possible (ideally a straight line). The straight line drawn before the transverse stretching is transformed into a bow shape in the pulling process after lateral stretching according to the magnitude of the pulling tension (this is called "Boeing"), and this bowing may remain even after the tension is removed. Has been observed. Although the detailed mechanism of the occurrence of bowing is unknown, the size of this bowing changes with the same tendency as the degree of non-uniformity of the longitudinal stretching ratio of the film. You can find the tension. Regarding the measurable film, the value of the take-up tension at which the film thickness of the film after transverse stretching measured by a film thickness measuring device becomes uniform in the width direction may be set. In this way, it is desirable to experimentally determine the optimum value of the take-up tension according to the stretching conditions of the film, and organize the data. Although one embodiment according to the present invention has been described above, the embodiment can be changed without changing the gist of the present invention, for example, as follows. The take-up roller need not be provided with a nip roller as long as the film can be reliably taken out, and the take-up roller may be attached to the machine frame of the transverse stretching device or the winding device. The structure of the lateral stretching apparatus for the film is not limited as long as it can hold both edges of the film. As the urging mechanism 10 of the dancer roll 9, the weight of the dancer roll alone is used, or a weight is additionally used,
A fluid pressure cylinder or screw jack may be used to change the position of the other end of the spring, one end of which is directly or indirectly locked to the dancer roll, to provide a biasing means such as a type that adjusts the tension force or compression force of the spring. good. In addition, the adjustment part of the urging mechanism is not limited to the pressure adjustment valve.
A known device that can be operated at any time depending on the structure of the urging mechanism can be used. The dancer roll is not limited to the one provided between the two guide rollers. Further, the direction of movement of the dancer roll is not necessarily limited to the vertical direction. The dancer roll may be guided by a linear guide mechanism or a mechanism that swings about a shaft as a fulcrum. The device for detecting the displacement of the dancer roll may be not only a device that detects the displacement of the dancer roll as an electric signal, but also a device that detects the displacement of the dancer roll as a fluid pressure or a mechanism that mechanically transmits the displacement to the speed control device. Further, the detected displacement signal of the dancer roll can be directly compared with the line signal without being compared with the reference signal. As described above, according to the present embodiment, the tension distribution of the belt-shaped sheet S of the film which is being stretched by the transverse stretching device is adjusted by the sheet take-up tension setting device so as to be uniform over the entire sheet width, and the stretching unevenness, It is possible to continuously form a band-shaped sheet of a high quality film with little thickness unevenness. Thus, the effect created by the take-up tension control device of the embodiment of the present invention is a defective product as pointed out in the related art and its problems, that is, a film in which the longitudinal stretching ratio in the width direction is not uniform in the transverse stretching process. The fundamental cause of the problem that the wrinkles and the straightness when the film is wound on the original fabric are impaired and the divided wound product in the next step cannot be obtained satisfactorily is solved. In the case of a product in which the longitudinal stretching ratio in the width direction of the laterally stretched film is not uniform, it is the actual situation at the operation site that a large amount of trimming is applied to both ends to save the product. By improving the longitudinal stretching ratio to be as uniform as possible and reducing the trimming amount to the minimum necessary for repeating the winding process twice, the raw material-to-product yield is improved. An example of the trial calculation is introduced below. In the conventional machine, before winding the original roll, in addition to the part that is gripped with grip and inevitable trimming, the sheet width trimmed both sides (ear picking) in consideration of stabilizing the quality is , 200mm × 2 = 400mm. The device of this embodiment can reduce the edge width to at least 1/2 or less, and if the total width of the sheet with ears is 5.7 m, it is 0.2 / 5.
7 × 100≈3.5% By carrying out this embodiment, it is possible to increase the raw material-to-product yield by 3.5% only by this film forming step. As a result, it is possible to increase annual production by 2,500R x 350 days x 3.5% = 30,625R (R; R) for just one film-forming line in this class. At present, the trimming loss in the slitter part when rewinding the original roll in the split winding step and winding the film roll is the same reason as above, that is, to stabilize the quality,
The average width is 150mm x 2 = 300mm. Similarly, the trimming loss can be reduced to 1/2 to 1/3 by stabilizing the quality of the stretched film to a high level, which corresponds to an increase in product yield of about 2%. Therefore, the production of 2,500R per day would be 2,500 x 2% x 350 days = 17,500R / year, and if both processes are combined, it would be 30,625R + 217,500R = 48,125R / year, which would increase the yield. However, 1R (ream) = 500 m ² (in the case of 20 μ film) According to this embodiment, it is possible to significantly increase the yield of a simple product such as the above value even if it is conservative. Even if all of the trimmings could be recycled as raw materials (the fact is that 100% recovery is not always possible), the loss is a significant factor in reducing manufacturing costs. All costs associated with the operation of the device until it is formed are impaired.

【The invention's effect】

According to the present invention, depending on the stretching conditions such as the film material and the thickness in the transverse stretching device by operating the pressing tension adjusting portion of the urging mechanism, the take-up tension is set to the optimum value (in the transverse stretching device at an appropriate time) even during operation. The pulling tension applied to the stretched film when the longitudinal stretching ratio of the film becomes substantially uniform in the width direction can be adjusted. Also, since the pulling tension is applied to the film by adjusting the pressing force of the dancer roll, it is possible to freely and finely operate the film during operation.
The tension can be controlled stably over a wide range. Furthermore, the tension fluctuation of the film caused by the difference in the inertial force between the stretching device drive system and the take-up device drive system at any time during start-up of the stretching device, during speed change for thickness change, and during normal operation. Absorbed by the dancer roll,
Prevents film breakage and always maintains stable operation. As described above, it is possible to prevent defects such as local wrinkles and sagging of the film, which have conventionally been caused by the incompatibility of the take-up tension of the film, and it is possible to form a good quality film even in the stretching of an ultrathin film. . As a result, the yield rate is increased in the steps subsequent to the transverse stretching apparatus, the productivity is improved, and the like, which brings about special actions and effects that cannot be expected from conventional apparatuses.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of one embodiment of the present invention, and FIG. 2 is
FIG. 3 is an explanatory diagram showing the stretched state of the sheet during stretching when the take-up tension is larger than the proper value, and FIG. 3 is an explanatory diagram showing the stretched state of the sheet during stretching when the take-up tension is smaller than the proper value. . Explanation of code 1 …… Take-off roller 1 ′ …… Nip roller 2 …… Guide roller 5 …… Line speed detection device 8 …… Speed control device 9 …… Dancer roll 10 …… Biasing mechanism 10 ′ …… Pressing force adjustment unit 11 ...... displacement detecting device T ...... film stretching device T c _...... clip S ...... sheet M 1 _...... take-up drive motor.

Claims (1)

[Claims] 1. A film take-up device for holding both edges of a synthetic resin material with clips, and taking a film sent out from a film lateral draw device that draws at least in the width direction by a take-up roller, said lateral draw device. And a take-off roller, a dancer roller provided between the take-off roller and the take-up roller, and a proper take-up tension at which the longitudinal stretching ratio along the width direction of the film sent out from the lateral stretching device becomes substantially uniform. And a rotation force of the take-up roller so as to return the dancer roll to a reference position upon receiving a detection signal from the displacement detection device of the dancer roll and the displacement detection device of the dancer roll. A film take-up device comprising: a speed control device for controlling a speed.