Cutting – With means to control or modify temperature of apparatus or... – Of tool
Patent
1992-01-20
1994-05-24
Jones, Eugenia
Cutting
With means to control or modify temperature of apparatus or...
Of tool
83175, 83346, 83660, 83678, B26D 140, B26D 714, B26F 120
Patent
active
053138635
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and method for continuously forming slits in a film.
2. Prior Art
Japanese Patent Publication No. Sho 61-11757 discloses an apparatus for forming slits in a film. The outline of this apparatus will be described hereunder.
Referring to FIGS. 17(a) and 17(b), a rotary blade assembly 1 is made of circular blades 12 having plural arcuated blade tips, the blades 12 being arranged around a shaft 11 in parallel with one another and at a predetermined interval or pitch between one blade and the adjacent one. By passing a film 3 through between the rotary blade assembly 1 and a backing roller 2, there is obtained a film having slits formed parallel to the length of the film and according to the shapes of the blades. FIG. 18 illustrates the film 3 in which slits are formed by this apparatus. Reference numeral 35 denotes slits formed in the film 3; and 34a and 34b, non-slit margins (regions near two side ends) of the film, respectively. The backing roller 2 is made of a high molecular material, e.g., rubber and plastics, in order to decrease wear of the blade tips of the expensive rotary blade assembly.
When a continuous operation is performed on a film with this apparatus, satisfactory proper slits cannot be obtained, and there is raised the problem that the film often tears in the subsequent stretching step. The service life of the backing roller made of a high molecular material is very short. Satisfactory slits cannot be formed by the continuous operation of this apparatus possibly because of various errors, e.g., unsatisfactory accuracy in sizes of the rotary blade assembly and the backing roller, an error in the rotation thereof, and non-uniformity in film thickness. For example, the rotating units such as the rotary blade assembly 1 and the backing roller 2 have a dimensional error caused when worked and an error exhibited during the rotation thereof. More specifically, these errors include off centering caused in this conventional apparatus by unsatisfactory perpendicularity of the circular blades to the axis 11 (or unsatisfactory parallelism between one circular blade and the adjacent one), unsatisfactory circularity of the section of the roller, insufficient precision of bearings and unsatisfactory accuracy in installation of this apparatus. Said errors also include non-uniformity of heights of individual blade tips of the circular blades and unevenness of the surface of the roller. Said errors further include considerable variation of the film in thickness. These various errors are superposably affect and cannot be avoided in machining.
When the backing roller has elasticity, an amount of elastic deformation varies depending on the extent of errors, and a push pressure proportional to the elastic deformation also varies accordingly. As a result, when slits are to be formed, the pressing forces at different portions of the film vary, failing to obtain satisfactory slits. The higher the running speed of the films is, the more remarkable the variation in pressing force is.
The surface portion of the backing roller 2 is made of a comparatively soft high molecular material, and it is thus very liable to be damaged and this damage will be quickly aggravated during the operation of this apparatus. Thus, in anticipation of such variation as above to some extent, the pressing force is generally adjusted. However, if the pressing force is set to be smaller so that the damage is less worsened, then satisfactory slits will not be formed.
When the damage or injure in the surface portion of the backing roll 2 is substantial, V- or U-shaped cuts 25 are found in the surface portion as indicated in FIG. 19(a). Accordingly, to form satisfactory slits in a film, the pressing force of the rotary blade assembly and the like must always be adjusted.
In the above apparatus, the blade tips are heated. As is indicated in FIG. 19(b), as the damage or cuts 25 in the backing roller 2 are deepened, the area and time of contact between
REFERENCES:
patent: 3875836 (1975-04-01), Hutchinson et al.
patent: 4691606 (1987-09-01), Johnson et al.
Aihara Kintaro
Honda Tadashi
Jones Eugenia
Nippon Petrochemicals Co. Ltd.
LandOfFree
Apparatus for forming slits does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for forming slits, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for forming slits will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1965751