Abstract:
A multi-roll segment package ( 101 ) for plastic tape comprises a plurality of roll segments made up of concentrically disposed spiral winding groups ( 119 ) separated and defined by helical winding portions of tape ( 121 ) connecting the spiral winding groups on adjacent roll segments. The spiral winding groups of the end roll segments ( 111 A), ( 111 B) comprise at least 2.5 times the number of windings as the center roll segments ( 115 A), ( 115 B), ( 115 C). The roll package features high wind density and good resistance from telescoping.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to winding and, more particularly, to winding plastic tape on cores. 
     Plastic tape has become commonplace in a number of products including electrical products such as wire, cable, conduit, transformers and other electrical components, as well as in packaging. The use of plastic tape as ties in plastic garbage and storage bags has grown significantly. Manufacturers utilize plastic tape in the form of rolls in automated machinery to produce a wide range of these products. 
     Rolls of plastic tape are normally wound on cores to aid in winding and provide improved stability of the roll. They are sometimes wound as a single “pancake” package which comprises a single roll having a width equal to the width of the plastic tape or film. Such a roll has the disadvantage of becoming unstable at large roll outer diameters, especially if the tape is narrow. The single roll package also limits the length of plastic tape, requiring frequent stopping of the machinery for roll changes. 
     Another winding method for roll packages utilizes a helical winding method, similar to winding a reel of line or string. This method produces a roll package with a width greater than the tape width and provides additional capacity of the roll package as compared to the “pancake” roll package. This winding method suffers the disadvantage of instability, especially near the roll package ends. Use of spools with end discs improves the stability, but increases the complexity, cost and weight of the package. 
     U.S. Pat. No. 4,603,817 discloses a tape package comprising a winding method which incorporates a plurality of axially spaced wind positions. The wind positions are made up of a plurality of separate spiral windings of at least one turn. Helical windings connect spiral windings to adjacent positions. The spiral winding groups of the end positions have twice the windings of intermediate positions. Although this method has some advantages over other winding methods, roll density is reduced due to frequent helical winding transitions or steps, and end stability still limits wind diameter. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     Therefore an object of the present invention is to provide a roll package for plastic tape comprising multiple roll segments with reduced transition steps on the outer roll segments, especially the end roll segments. 
     A further object of the present invention is to provide a roll package having a high wrapping density, increasing the length of tape in a given package outer diameter. 
     A further object of the present invention is to provide a roll package which may be wrapped to larger roll diameters, increasing the capacity of the roll package. 
     A further object of the present invention is to provide a roll package with improved mechanical stability, reducing the reject rate of roll packages due to damage. 
     Surprisingly, it has been found that the helical transition windings between the spiral winding groups in prior art roll packages de-stabilize the roll segments, especially the end segments. This is believed due to non-uniformities introduced in the tape resulting from the stresses on the tape as the winding is stepped or axially displaced to an adjacent roll segment. The non-uniformities also reduce the winding density of the roll segments. 
     The roll package of the present invention comprises a single length of plastic tape wrapped on a core in a plurality of roll segments. In the preferred embodiment, the tape is continuous between the beginning of the tape at the core to the end at the segment outer diameter of the last roll segment. The roll segments are the approximate width of the tape. Each roll segment is made up of a plurality of concentrically disposed spiral winding groups. The winding groups comprise a plurality of continuous and non-interrupted spiral tape windings. The spiral winding groups of a roll segment are connected to spiral winding groups on adjacent roll segments by helical windings produced as the winding process “steps” to the next roll segment as the roll package is built up. 
     The roll segments of the roll package include two end roll segments and a plurality of inner roll segments. The inner roll segments of the preferred embodiment comprises at least two intermediate roll segments positioned adjacent to the end roll segments and axially displaced towards the center of the roll package, and at least one center roll segment positioned adjacent to an intermediate roll segment and axially displaced towards the center of the roll package. The spiral winding groups of the end roll segments have more individual tape windings than the spiral winding groups of the intermediate roll segments. At least a portion of the spiral winding groups of the intermediate roll segments have more individual tape windings than the spiral winding groups of the center roll segment(s). 
     In one of the embodiments, the spiral winding groups of the end roll segments comprise at least twice the number of windings as the spiral winding groups of the intermediate roll segments. At least a portion of the spiral winding groups of the intermediate roll segments comprise at least twice the number of windings as the spiral winding groups of the center roll segment(s). 
     In a preferred embodiment, the spiral winding groups of the end roll segments comprise approximately three to four times the number of windings as a first portion of spiral winding groups of the intermediate roll segments. The spiral winding groups of the end roll segments comprise approximately eight times the number of windings as a second portion of spiral winding groups of the intermediate roll segments. The first portion of the spiral winding groups of the intermediate roll segments comprise at least twice the number of windings as the spiral winding groups of the center roll segment(s). 
     The roll package structure of the present invention results in the end roll segments having less than half the number of spiral winding groups (or roll segment visits) as compared to the spiral winding groups of the center roll segments. In the preferred embodiments, the number of spiral winding groups making up the end roll segments is less than one fourth, more preferably less than one sixth, and most preferably approximately one eigth of the number of spiral winding groups as the center roll segments. The reduced number of spiral winding groups of the end roll segments increases the winding density of the end roll segments and improves the stability of the end roll segments by reducing the number of helical winding transitions and the resulting non-uniformity of the tape windings. 
     In the preferred embodiments, the end spiral groups comprise at least 2.5 times the number of wrappings as the center spiral groups. In the more preferred embodiments, the end spiral groups comprise at least 3 times the number of wrappings as the center spiral groups. In the yet more preferred embodiments the end spiral groups comprise at least 4 times the number of wrappings as the center spiral groups, and in the still more preferred embodiments, the end spiral groups comprise at least 6 times the number of wrappings as the center spiral groups. In the most preferred embodiments, the end spiral groups comprise at least 8 times the number of wrappings as the center spiral groups. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other features, aspects and advantages of the present invention will become better understood with regard to the following description, appended claims and accompanying drawings where: 
     FIG. 1 is a perspective drawing of a multi-roll segment package of the present invention showing the package being wound on a core, several helical winding portions shown transitioning the winding from one roll segment axially to an adjacent roll segment; and 
     FIG. 1A is a detail end view of several spiral winding groups on the end roll segment, the spiral winding groups consisting of several spiral wind layers and separated from adjacent, concentrically disposed spiral winding groups by helical winding portions. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following is a description of the preferred embodiments of a multi-roll segment package of a single, continuous length tape and a method for making the package. 
     FIG. 1 is a perspective drawing of roll package  101 . A winding machine such as that disclosed in related application Ser. No. 09/054,667, now U.S. Pat. No. 6,007,016, hereby included by reference, rotates core  103  in direction  105  about roll package axis  107 . The machine feeds a continuous length of plastic tape  109  to build up roll package  101 . 
     Roll package  101  comprises end roll segments  111 A and  111 B, intermediate roll segments  113 A and  113 B, and center segments  115 A,  115 B, and  115 C. Each roll segment is made up of concentrically disposed spiral winding groups such as spiral winding groups  117 A and  117 B of detail FIG.  1 A. Spiral winding groups  117 A and  117 B are made up of at least two continuous, uninterrupted tape windings or layers  119 , spirally wound on each other. Helical winding portions such as portions  121  define the radial boundaries of spiral winding groups and connect a winding group on a roll segment to a spiral winding group of an adjacent roll segment. Helical portions  121  occur when tape  109  traverses or steps to an adjacent segment after winding a plurality of spiral windings on the group of the previous roll segment. 
     Experimentation and trial have demonstrated improved roll package stability by winding spiral winding groups on end roll segments  111 A and  111 B with a relatively large number of windings as compared to intermediate and center roll sections. The relatively larger number of windings on end roll segment spiral winding groups reduces the number of helical winding portions, increasing the wind density and stability of the end roll segment. 
     EXAMPLE 1 
     A 1″ wide by 0.004″ thick plastic tape was wrapped on a fiber core beginning on roll segment  111 A position. A wrapping machine wrapped 32 layers of tape, forming the first spiral wind group of roll segment  111 A. After a helical portion  121  wrap to roll segment position  113 A, four layers were wrapped to form the first spiral wind group of roll segment  113 A. The winding machine wrapped center roll segments  115 A,  115 B, and  115 C in a similar fashion with four layers in each spiral wind group. Intermediate roll segment  113 B position was wrapped with nine layers, the helical winding direction reversed towards end roll segment  111 A, and the center roll segments wound with four windings in each spiral winding group. At the machine&#39;s second visit to intermediate roll segment  113 A, nine layers were wrapped, followed by a reversal of the helical winding direction towards end roll segment  111 B. The machine wrapped four windings on each group of center roll segments, and four on intermediate roll segment  113 B, followed by 32 windings on end roll segment  111 B. 
     The machine reversed helical wrap direction again towards end roll segment  111 A, wrapping four windings on intermediate roll segment  113 B and on each center roll segment, nine on intermediate roll segment  113 A, reversed direction, wrapping four windings on each center roll segment and nine on intermediate roll segment  113 B. Once again, the machine reversed helical wrapping direction towards end roll segment  111 A, wrapping four layers on each center roll segment, four on intermediate roll segment  113 A, and starting the new cycle with 32 on end roll segment  111 A. 
     The roll package resulting from the wind sequence provided improved end roll segment stability as compared with earlier roll package methods winding twice the windings on roll end segments as compared with all or, substantially all, of the inner segments. The roll package allowed larger wrapped diameter, increased capacity, and improved resistance to telescoping and roll damage as compared with previous methods. 
     Accordingly the reader will see that the MULTI-ROLL SEGMENT PACKAGE FOR PLASTIC TAPE disclosed and claimed provides an improved roll package for plastic tape. The roll package provides the following additional advantages: 
     The roll package density is high, increasing the length of tape on a given size roll package, reducing converting roll change time and shipping costs; 
     The roll package is stable, reducing roll package damage and waste; 
     Larger package diameters may be wound, reducing converting equipment change time and shipping costs; and 
     The roll package is simple to make and use. 
     Although the description above contains many specifications, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example, in some embodiments, all of the spiral winding groups meet the relative winding number specifications in this disclosure. In other embodiments, the majority, or at least a substantial number of, the spiral winding groups meet the relative winding number specifications. Deviation of the relative group winding numbers or frequency of visits for a portion of the total roll segment wind does not depart from the spirit of the invention, that is to reduce the number of visits and increase the number of windings in the end spiral groups of the end roll segments as compared to the intermediate and center roll segments of prior art rolls. In other embodiments, one or more helically-wound “wrapping layers” are wound over the roll segments to provide a protection and a stabilizing cover for the roll package. 
     Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.