JPH0139897B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a width-spreading device used on a plastic film travel path to prevent wrinkles from occurring in the traveling plastic film.

(Prior Art) Conventionally, as a device for expanding the width of a traveling plastic film, a curved roller, a so-called expander roller, which is rotated by a drive mechanism or a frictional force between it and the traveling plastic film, for example, a first roller,
As shown in Fig. 2, a series of flexible cylinders capable of contacting at least the entire width of the plastic film, for example, a rubber cylinder 3b containing a ball bearing, is used.
An expander roller of a type that rotates around the outer periphery of a curved fixed shaft 3a was used. As shown in FIGS. 1 and 2, this expander roller is placed in the sheet running path between the front and rear guide rolls 1 and 2 so as to push up (push down) the running sheet S. The traveling plastic film pressed against this moves in the direction of rotation of the expander roller, that is, the central part of the plastic film S that touches the vicinity of the center of the rubber tube 3b moves straight, and the farther left and right the part, the more it moves.
It will be advanced diagonally outward at a large angle (see Figure 2). As a result, the longitudinal wrinkles of the traveling sheet S are eliminated and the sheet is expanded to its original width.

(Problems to be Solved by the Invention) However, plastic film has a smooth surface and is more slippery than woven cloth, etc. Furthermore, in the case of recent high-speed sheet running paths, plastic film and roll An air table phenomenon is added that traps air in between and drastically reduces the coefficient of friction. on the other hand,
The sheet width widening action of the expander roller above is as follows:
This is achieved by generating a certain amount of frictional force between the traveling plastic film and the expander roller. Therefore, it has become impossible to obtain a sufficient width-expanding effect using conventional expander rollers.

On the other hand, plastic films have recently become thinner; for example, OPP has a thickness of 20 to 60μ, while PET has a thickness of 20 to 60μ.
Thicknesses of several microns, 12μ or smaller, are also manufactured. If such a plastic film is not run under extremely low tension, the winding quality etc. will be impaired. For example, if the tension in the running direction of the running sheet is set to a large value in the plastic film running path leading to the winding section in the plastic film manufacturing process or the winding process, the width of the running plastic film may be narrowed and vertical wrinkles may occur. This not only causes permanent elongation and defects in the plastic film on the running path, but also causes it to be fed to the winding section and wound up with excessive residual stress. In the film roll wound in such a state, the inner layer part is tightened by the tension of the outer layer part of the film roll, and a so-called winding phenomenon occurs, resulting in a product defect. That is, if the tension in the direction in which the plastic film runs, which is essential when using an expander roller, is excessive, it will have a very negative effect on the plastic film.
However, in order to obtain a sufficient width-expanding effect with conventional expander rollers, it is necessary to increase the frictional force between the sheet and the roller. The required tension in the plastic film running direction must be applied to the plastic film. Therefore, conventional methods cannot be effectively applied to plastic films.

Further, it is not possible to use the method of squeezing the entire width of the plastic film between upper and lower rollers because it causes folding wrinkles that have a fatal adverse effect on the quality of the plastic film.

Furthermore, in order not to impair the quality of the thin and easily stretchable plastic film, it is necessary not only to keep the tension of the plastic film at a low value, but also to apply localized excessive stress in the width direction to the plastic film while it is running. It is necessary to prevent this from occurring. This avoids permanent elongation of the plastic film due to stress concentration, scratches on the sheet, or vertical wrinkles in the plastic film, which can lead to fatal overlapping wrinkles. It's for a reason. Therefore, local pinching of the plastic film in the width direction of the plastic film must be avoided as this will disturb the stress distribution in the width direction of the plastic film during travel and cause localized excessive stress. Must be.

(Means for Solving the Problems) Therefore, the traveling plastic film width expanding device of the present invention is rotatable while maintaining a curved posture in a predetermined direction, and has a length that can contact the entire width of the traveling plastic film. The present invention is characterized in that a plastic film running path provided with a series of curved rollers having a width is provided with a rotatable pressing roller that pinches only both edges of the running sheet between itself and the curved rollers.

(Function) Therefore, the present invention provides a series of curved rollers that are capable of rotating only both edges of a traveling plastic film while maintaining a curved posture in a predetermined direction, and that are capable of contacting the entire width of the traveling plastic film. By sandwiching only the edges of the running plastic film between the bending roller and the rotatable pressing rollers, the frictional force between the edges of the running plastic film and the bending roller can be reduced. enhance

(Example) Figures 3 and 4 show an example of the present invention, in which the previously mentioned conventional expander roller 3 (same type as in Figures 1 and 2) is used as the curved roller. A running plastic film S is brought into contact with the outer periphery of the panda roller 3. At both edges of the traveling plastic film on the expander roller 3, pressing rollers 5 are arranged symmetrically and parallel to the axis of the expander roller 3, respectively.

Each of the pressing rollers 5 in this embodiment is pivotally supported at the tip of an arm 7 that freely swings around a horizontal support rod 6. Therefore, the pressing roller 5 of this embodiment
is pressed against the expander roller 3 by gravity, and the traveling plastic film S is sandwiched between this expander roller and the expander roller 3. However, it is also possible to make the pressing force variable by using known techniques such as balance weights, springs, and fluid pressure cylinders. Further, it is easy to add an active rotation function to the pressing roller 5. The support rod 6 is removably inserted into the through hole of the support block 8, and is tightened and fixed by turning the head handle 9. The support block 8 is mounted on a stand (not shown) so that the rotation can be adjusted when changing the direction of the pressing roller 5. Therefore, the pressing roller 5
In order to make the width of the plastic film S correspond to the width of the traveling plastic film S, the support rod 6 can be moved out or withdrawn from the support block 8, and in order to make the direction of the pressing roller 5 correspond to the direction of the expander roller 3, The rotation of the support block 8 may be adjusted. Note that if the expander roller 3 is made of a flexible cylinder (in this embodiment, the rubber cylinder 3b) whose degree of curvature can be varied by changing the curvature, then the traveling plastic can be used. The degree of curvature of the expander roller 3 and the direction of the pressing roller 5 can be changed based on the value of a predetermined force in the width direction due to the material of the film S, etc. There are various types of support mechanisms for the expander roller, including one that allows the expansion effect to be adjusted by changing the direction of curvature of the expander roller, but these are all well known and are therefore omitted from the drawing. . Furthermore, the method of supporting the pressing roller does not matter.

A running plastic film S whose edges are sandwiched between a pressing roller 5 and an expander roller 3
generates a widthwise component force T because it receives a frictional driving force F diagonally outward at an angle θ with respect to the plastic film running direction according to the curvature of the expander roller 3, and is mainly caused by this widthwise component force T. It can be expanded in the width direction. Therefore, the conditions that affect the width widening action are the pressing force of the pressing roller 5, the frictional driving force between the expander roller 3 and the traveling plastic film S, and the magnitude of the angle θ.
By appropriately adjusting the above three conditions according to the conditions of the running plastic film, the most effective width widening effect corresponding to the running plastic film can be obtained. Note that it is most effective to support the pressing roller by adjusting its angle so that the axes of the pressing roller and the expander roller are completely parallel, but even if they are not completely parallel, Even if there is play, no particular problem will arise if the frictional force between the expander roller and the traveling plastic film can be increased by the pressing roller.

Although the present invention has been described above based on one embodiment, it goes without saying that the embodiment may be modified and applied as appropriate without departing from the scope of the claims.

(Effects of the Invention) According to the present invention, both edges of the traveling plastic film are sandwiched between the pressing roller and the curved roller,
By increasing the frictional force between the edges and the surface of the curved roller, the traveling plastic film can be reliably guided diagonally by the curvature of the curved roller, even under low tension. The widening action of the plastic film can be reliably produced mainly at both edges of the running plastic film. Moreover, a substantially uniform stress distribution can be maintained in the central portion that is not sandwiched between both rollers. In this case, stress tends to concentrate on both edges of the plastic film, which is supported and guided by a series of curved roller surfaces that inherently have a widening effect over the entire width of the plastic film.
There is no problem because local deformation of the plastic film in the width direction is regulated on the surface of the curved roller. Furthermore, there is no possibility of localized permanent stretching or damage to the running plastic film, especially at the ends of the pressure rollers. In addition, even if wrinkles occur on both edges and are folded into wrinkles due to being squeezed, there will be no negative impact on the actual product because both edges are usually cut off as ears. do not have. Therefore, even if the running plastic film is made of a thin and easily stretchable material that needs to be run under low tension, it is possible to reliably spread it to its original width and run it without causing problems such as wrinkles. It becomes possible. Furthermore, it can fully meet the recent demand for faster running plastic films. Moreover, basically simple elements such as a curved roller and a pressing roller are sufficient, and no complicated mechanism is required. Therefore, it can be easily attached to existing equipment and has extremely high practicality.

[Brief explanation of drawings]

1 and 2 are elevational and planar explanatory views of a conventional expander roller, and FIGS. 3 and 4 are elevational and planar explanatory views of an embodiment of the present invention. 4... Curved roller (expander roller), 5
...Press roller.

Claims (1)

[Claims] 1. A plastic film running path is provided with a series of bending rollers that are rotatable while maintaining a curved posture in a predetermined direction and have a length that can contact the entire width of the running plastic film, and the plastic film is run between the above-mentioned bending rollers. A device for widening a traveling plastic film, characterized in that it is provided with a rotatable pressing roller that pinches only both edges of the plastic film.