Buckles – buttons – clasps – etc. – Including readily dissociable fastener having numerous,... – Having mounting surface and filaments constructed from...
Reexamination Certificate
2002-01-16
2004-02-10
Sandy, Robert J. (Department: 3677)
Buckles, buttons, clasps, etc.
Including readily dissociable fastener having numerous,...
Having mounting surface and filaments constructed from...
C024S442000
Reexamination Certificate
active
06687962
ABSTRACT:
TECHNICAL FIELD
This invention relates to patterning touch fastener elements, and more particularly to self-engageable patterns of mushroom-type fastener elements.
BACKGROUND
Touch fasteners generally include those with male fastener elements, such as those shaped as mushrooms, palm trees or hooks, engageable with loop or fibrous elements or with complementary arrays or patterns of male fastener elements. Patterns of male fastener elements that are engageable with themselves, or with another fastener having a similar pattern, are called self-engageable. To be self-engageable, a fastener element pattern must have an arrangement of fastener elements that allow the heads of two identical such arrays to pass by one another, and then to engage one another with their overhanging portions. In order for the heads of the mating fasteners to pass one another during engagement, the overall percentage of the area of each fastener element array occupied by the footprints of the heads, or the head density as it is sometimes called, must be less than 50 percent. The ratio of individual inter-element engagements to the total number of fastener elements of one of the identical engaged arrays is the bulk engagement ratio. Because one fastener element may be simultaneously engaged with multiple fastener elements of another array, it is possible for bulk engagement ratios to exceed 100 percent. Typically, the stems of the fastener elements are flexible to allow the heads to pass by one another as the fastener arrays are brought into engagement.
In many previous patterns of fastener elements, the elements were arranged in straight, ordered rows, and very efficient methods are available for molding fastener element stems integrally with a base in straight rows, such as by continuous molding of stems and base on a rotating mold roll made up of stacked plates, many plates each providing the cavities for a respective row of fastener element stems, as disclosed in U.S. Pat. No. 4,794,028. After stem molding, the fastener element heads may be formed by heating the stem ends and then pressing against them with a chilled surface, as is shown in U.S. Pat. No. 6,248,276, or by otherwise flowing resin of the distal stem ends to form overhanging heads. While readily formed, many straight-row patterns tend to perform best for self-engagement at an engagement angle, the angle between the directions of extent of the rows of the engaged arrays, of zero degrees. For enabling engagement at a variety of other angles, it has been suggested that fastener elements should be arranged with a very low degree of order rather than in equally spaced, straight rows. While such unordered arrangements can provide for more uniform engagement rations over a wide variety of engagement angles, such that the mating arrays can be engaged without precise alignment, this typically comes at a reduction in the bulk engagement ratio at a zero degree engagement angle, the engagement orientation occurring most frequently in many fixed-position applications, and places some limitations on manufacturing method. Furthermore, with most unordered patterns there will be some degree of undesirable direct overlap of the stem positions of the engaging arrays in almost any engagement orientation, forcing the overlapped stems to buckle or significantly deflect laterally to complete engagement. The ratio of the number of overlapped stems to the overall number of fastener elements in one of the arrays is called the bulk overlap ratio.
Many straight row or otherwise highly ordered patterns allow the engaged arrays of fastener elements to move laterally with respect to each other, or slip. Gross slip can occur in the direction of the rows of some straight row patterns, or in incremental motions in multiple directions in other patterns.
Further improvements in the arrangement of fastener elements in self-engageable patterns are desired.
SUMMARY
According to one aspect of the invention, a touch fastener product has a sheet-form base and an array of fastener elements, each fastener element having a stem extending from a broad side of the base to a distal head overhanging the base. The fastener elements are arranged in an ordered pattern of straight rows, with the heads of the fastener elements covering the base at a head density of between about 20 and 35 percent. The fastener elements are arranged to define a sufficient number and pattern of pockets between associated groups of adjacent stems to provide a bulk locking ratio of at least 10 percent when engaged with an identical pattern at a zero degree engagement angle. Preferably, the head density is between about 25 to 33 percent, or about 31 percent for some applications.
In some embodiments, the fastener elements are arranged to have a bulk engagement ratio, when engaged with an identical pattern at a zero degree engagement angle, of at least 100 percent, preferably at least 150 percent, and more preferably at least 200 percent.
In some cases, the bulk locking ratio is at least 20 percent, preferably at least 25 percent.
The fastener elements, for some applications, are advantageously arranged in a repeating pattern of row groupings, with each row grouping having a three row band of fastener elements spaced apart from adjacent rows of fastener elements by a distance greater than row spacing within the band. In some cases, the three row band consists of two outer rows of laterally aligned fastener elements and a middle row of fastener elements longitudinally offset from adjacent fastener elements of the outer rows. The middle row is preferably equidistant from two adjacent fastener elements of each of the outer rows.
In some configurations, a clearance between opposing surfaces of adjacent fastener element heads along the middle row is less than a nominal lateral extent, measured long the middle row, of the fastener element heads, such that during engagement, at least some of the fastener element stems of the middle row are deflected.
Preferably, particularly in such configurations, a clearance between opposing surfaces of adjacent fastener elements of the outer rows, measured across the three row band, is greater than a nominal lateral extent, measured long the middle row, of the fastener element heads, such that engagement does not require the deflection of both fastener elements of each opposing outer row pair.
In some patterns, each row grouping comprises the three row band and at least one single row band of fastener elements. For example, in one case, each row group consists of the three row band and a single row band of fastener elements spaced midway between the three row band of the grouping and a three row band of an adjacent grouping. In another illustrated pattern, each row group consists of the three row band and two single row bands of fastener elements separated by a distance greater than the row spacing within the three row band.
In some embodiments, the fastener elements are arranged in a repeating pattern of four-element clusters, with each cluster consisting of four fastener elements arranged at four corners of a four-sided polygonal area and spaced from adjacent clusters by a distance greater than a greatest side length of the polygonal area. The four-sided polygonal area may be rectangular, for example, or substantially square.
In some constructions, the fastener elements are arranged in a repeating pattern of four-element clusters, with each cluster consisting of four fastener elements arranged at four corners of a four-sided polygonal area. A clearance between a first pair of opposing fastener element heads at opposite corners of the area is greater than a nominal diameter of the fastener element heads, and a clearance between a second pair of opposing fastener element heads at opposite corners of the area is less than the nominal diameter of the fastener element heads.
For many touch fastener applications, the array should have an overall fastener element density of at least 200 fastener elements per square inch (31 fastener elements per square centimeter), preferably at least 500
Carbonneau Michael J.
Clarner Mark A.
Ennis Michelle M.
Fish & Richardson P.C.
Sandy Robert J.
Velcro Industries B.V.
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