Releasable strap

Details Releasable strap Releasable strap

2000-09-19

2003-04-22

Eashoo, Mark (Department: 1732)

Plastic and nonmetallic article shaping or treating: processes

With severing, removing material from preform mechanically,...

Forming continuous work followed by cutting

C156S244150, C156S244190, C264S157000, C264S171130

Reexamination Certificate

active

06551539

ABSTRACT:

TECHNICAL FIELD
This invention relates to releasable straps. One use of a releasable strap is the temporary tying together of loose components of an automobile wiring harness after manufacture, for delivery from the manufacturer to a remote automotive assembly plant. At the assembly plant the strap is removed by an assembly line worker as the wiring harness is installed.
BACKGROUND
A desirable strap for such temporary bundling of wiring harnesses and other materials is a so-called hook and loop strap, which has a field of loop-engageable hooks extending along one side of the strap and a field of hook-engageable loops on the other side. Typically the entire surface of the sides of the strap comprise hook and loop materials, respectively. The hook and loop materials are designed to be aggressive to assure that the wiring harness bundle or other materials remain undisturbed during handling.
The complementary fastener hooks and loops permit releasable hook-and-loop fastening when the strap is wrapped e.g., about the wire harness and over itself so that a region of hooks on the inside surface of the strap engage with loops on the strap's outside surface. A worker in an automotive assembly line can then grasp the end of the aggressive strap and peel the engaged strap portions apart to release the wiring assembly. Because the worker typically wears gloves, it has been common to apply a masking material to the end of the strap on the hook-side to provide a plain end to the strap, i.e., an end that has no hooks available to engage the loops. This end portion then stays free of the loops and provides a portion to be grasped and pulled to peel the fastener components apart to, release the strap.
Typically, such strap products have been formed by applying continuous lengths of loop material to continuous lengths of hook material. The continuous laminated material has then been cut longitudinally (in the machine direction) into continuous strips of suitable width. These strips have then been cut to the desired length. An excellent way of forming the base hook and loop material has been by the process shown in Kennedy et al. U.S. Pat. No. 5,260,015, in which, during molding of the hooks on a rotary mold, a pre-formed loop fabric is laminated to the side of the base layer opposite that from which the hooks extend, while the hook material is on the mold roll, so-called “in situ” lamination.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a method is provided of forming a releasable strap of hook and loop material, the strap having a hook side and a loop side, the hooks being formed of synthetic resin on a mold roll that has a multiplicity of hook mold cavities. According to this aspect of the invention, the mold roll has at least one relatively wide-hook molding region, and has, at least at one side of the hook-molding region, a relatively narrow region devoid of hooks. Using this machine, a continuous sheet material is produced having, in the machine direction, on one side a wide band of loop-engageable hooks and an adjacent relatively narrow band devoid of the hooks, while hook-engageable loops are on the opposite side of the material. The method further involves repeatedly cutting the continuous material at a substantial angle to the machine direction, the cuts extending across the wide and narrow bands to define a series of straps of constant pre-selected length, each strap being characterized by having fastener loops on one side and on the other side a main length portion covered with fastener hooks and at least one end portion devoid of hooks.
The invention also features a method of forming a releasable strap of hook and loop material, the strap having a hook side and a loop side,the hooks being formed of synthetic resin on a mold roll defining a multiplicity of hook mold cavities, the method comprising providing a mold roll having at least one relatively wide hook molding region over which hook mold cavities are distributed and, at least at one side thereof, a relatively narrow region devoid of hooks, and exposing both regions to plastic resin and utilizing the mold roll to form a continuous sheet of material having on one side a wide band of loop-engageable hooks and an adjacent relatively narrow band of resin devoid of hooks, while hook-engageable loops are on the opposite side of the material, and repeatedly cutting the material at a substantial angle to the machine direction, the cuts extending across the wide and narrow bands, to define a series of straps of constant pre-selected length having hook-engageable loops on one side and, on the other side, a main length portion covered with hooks and at least one end portion that is devoid of hooks and stiffened by resin.
In another aspect of the invention, the above methods are performed omitting the portion of the mold roll devoid of hooks, to produce straps by cross-wise or angled cuts.
Preferred embodiments of the invention have one or more of the following features.
On the mold roll there are relatively narrow regions devoid of hooks on both sides of the relatively wide hook mold region, and the method provides straps having on the hook side, end portions at both ends of the strap that are devoid of hooks, and which, in many instances, are preferably stiffened by the resin.
Preferably, for use for instance in securing automotive harnesses, the end portions devoid of hooks are sized to enable grasping by a gloved worker to exert pull on the strap to peel the hooks from their engagement with the loops that they overlap.
Advantageously, a rotary cutter can be employed having parallel cutting elements that are spaced apart by the desired width of the straps, to form cuts or perforations in the continuous length of material.
In one preferred case, the elements of the rotary cutter are helically arranged to make the cuts or perforations in lines at a substantial acute angle to the machine direction, and the resulting straps taper to points at their ends. In another case the cuts or perforations are made in lines at a right angle to the machine direction, resulting in straps having square ends.
Advantageously, the methods are conducted in such manner that the cutting is controlled to partially sever or partially perforate the straps to form lines of substantial weakening, but leaving the straps connected sufficiently to enable the overall material to be rolled into the form of a supply roll from which individual straps or groups of straps can be detached by breaking away at selected lines of weakening. In one preferred embodiment, the straps are approximately 19 inches in length. Portions having plain surfaces are preferably approximately 1 inch in length each.
Preferably, the strap material is formed by employing an extruder that introduces molten resin to the molding roll and the loop material is applied either simultaneously or immediately following the formation of a continuous hook strip, while the hook resin remains on the roll. Preferably methods as shown in Kennedy et al., U.S. Pat. No. 5,260, 015 or its variation, Murasaki et al., U.S. Pat. No. 5,441,687, are employed for in situ lamination of the loop material. These references are hereby incorporated by reference.
In one case the mold roll is utilized by forming a nip between the mold roll and a pressure roll, and introducing, to the nip, a sheet of molten resin from an extruder, while, preferably, preformed continuous sheet material defining the loops is introduced into the nip along with the resin in the manner that the sheet material is laminated in situ to a base layer of the resin while hooks are formed integrally by the mold roll on the other side of the resin.
In another case, a nozzle is shaped to define a mold region at a portion of the periphery of the mold roll and resin is introduced via the nozzle to the mold region from an extruder, while, preferably, preformed continuous sheet material defining the loops is introduced to the resin following the nozzle while the resin remains in the roll in the manner that it is laminated in situ to a base

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