U.S. patent number 3,629,032 [Application Number 04/841,944] was granted by the patent office on 1971-12-21 for method for making flexible strips of material having on one surface thereof a pile of upstanding hooking elements.
This patent grant is currently assigned to American Velcro Inc.. Invention is credited to George H. Erb.
United States Patent |
3,629,032 |
Erb |
December 21, 1971 |
METHOD FOR MAKING FLEXIBLE STRIPS OF MATERIAL HAVING ON ONE SURFACE
THEREOF A PILE OF UPSTANDING HOOKING ELEMENTS
Abstract
A method is disclosed for producing the hooked surface of a
hook- and loop-type fastener by treating a starting fabric material
having a pile of upstanding threads. The treatment comprises
impregnating the threads and pile with a liquid plastic monomer
having the capability of being converted by the application thereto
of a suitable form of energy to a flexible solid, applying heat or
other suitable form of energy to the underside of the starting
material to set the lower portion of the threads into a relatively
permanent and stiffened shape and then subjecting the other side of
said starting material simultaneously to a pressure and heat or
other suitable form of energy to bend and set the upper portions of
the threads into the form of hooking elements.
Inventors: |
Erb; George H. (Rutland,
VT) |
Assignee: |
American Velcro Inc.
(N/A)
|
Family
ID: |
25286138 |
Appl.
No.: |
04/841,944 |
Filed: |
July 15, 1969 |
Current U.S.
Class: |
156/196; 156/435;
428/85 |
Current CPC
Class: |
A44B
18/0038 (20130101); Y10T 156/1002 (20150115) |
Current International
Class: |
A44B
18/00 (20060101); B32b 003/06 (); B32b
007/06 () |
Field of
Search: |
;156/196,435
;161/48,51,52,63,64,65,66,67,140 ;24/DIG.18 ;128/DIG.15 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Montone; G. E.
Claims
I claim:
1. A method for producing a flexible strip of material in which are
anchored a multiplicity of hooking elements from a starting
material having a multiplicity of projecting threads, the method
comprising impregnating said threads with a liquid plastic monomer,
applying heat to that side of said starting material opposite to
the side carrying said threads for a period of time sufficient to
heat set the lower portion of said threads into a relatively
permanent straight configuration, and subjecting the other side of
said starting material to a pressure source and heat treatment
source to bend the upper portions of said threads into hooks
extending randomly in different directions and heat setting said
upper portions into relatively permanent hook shapes.
2. A method for producing a flexible strip of material in which are
anchored a multiplicity of hook-shaped elements, the method
comprising providing a length of flexible material with a
multiplicity of upstanding threadlike elements, impregnating said
elements with a liquid plastic monomer, applying heat to the
underside of said material for a period of time sufficient to heat
set the portions of said threads adjacent to said fabric, inverting
said material so that said threads assume an upright position and
simultaneously cooling said material thereby fixing said lower
portions into a relatively rigid straight-lined configuration,
subjecting said threads in said upright position simultaneously to
a pressure source and heat treatment source bending the upper
portion of said threads into hooked shapes extending randomly in
different directions and heat setting said upper portions into
relatively permanent hook shapes.
3. The method according to claim 1 wherein said pressure source and
said heat source is a controlled flow of hot gaseous material.
4. The method according to claim 2 wherein said pressure source and
said heat source is a controlled flow of hot fluid material.
5. A method for producing a flexible strip of material in which are
anchored a multiplicity of hooking elements from a starting
material having a multiplicity of projecting threads, the method
comprising impregnating said threads with a liquid substance having
the characteristic of becoming flexibly solid upon exposure to a
source of energy, exposing the side of said material opposite to
the side from which said threads project to an energy source for a
period of time sufficient to set the lower portion of said threads
into a relatively permanent straight configuration, and subjecting
the other side of said starting material to exposure to an energy
source and to pressure to bend and to set the upper portion of said
threads into hooks.
Description
FIELD OF THE INVENTION
This invention relates to a method and apparatus for forming
hooking elements from an upstanding pile of threads.
BACKGROUND OF THE INVENTION
Separable fastening devices of the prior art are generally made up
of two layers of flexible material, each layer being in the form of
a band or tape having on opposite faces thereof surfaces provided
with a multiplicity of small interengaging means which protrude
outward therefrom forming opposed pilelike fabrics. By preference,
the interengaging surfaces are those incorporated in fasteners
described in U.S. Pat. No. 3,009,235 wherein one surface includes a
multiplicity of small outwardly projecting loops of thin
filamentary material and the other surface is provided with a
multiplicity of curled or hooklike resilient projections.
It will be understood that when two layers of this type are pressed
into face-to-face contact, their respective hooking elements and
loops interengage one with the other thereby securing said layers
into locking engagement. Separation of the two layers requires a
force of considerable magnitude when attempting to effect the
separation of a large number of hooking elements and loops at once,
but separation may be quite readily effected by progressively
peeling the layers apart.
Fasteners constructed with interlocking hooking element and loop
members of the type described find a wide variety of applications.
For instance, they can be substituted for existing closing devices
such as buttons, buckles, clasps, slidable fasteners of the type
popularly termed zippers, or like attachments which are currently
used in many diverse types of wearing apparel. In addition, they
serve a useful function in many particular environments where it is
desired to fasten one object to another in a quick and efficient
manner.
The most common method until the present has been to form the
hooking elements by subjecting loops to the cutting action of a
device consisting of a comb of tapered needles having mounted
thereon small rapidly reciprocating scissorslike cutters which clip
each loop at a predetermined point thereby resulting in a hooking
element and stub formation. Among hooking elements produced by
existing methods uncut or partially cut loops are sometimes found
intermixed with the cut loops. The presence of such uncut loop is a
function of the extremely thin sectional mass and resilient nature
of the loops whereby they offer little resistance and therefore can
be pushed out of alignment and avoid the cutting operation.
It is a principle object of this invention to provide upstanding a
multiplicity of hooking elements which are randomly oriented and
which avoid many of the difficulties inherent in the product.
SUMMARY OF THE INVENTION
The method contemplated by this invention consists essentially of
providing a length of flexible material with a pile of upstanding
threads which are adapted to become permanently shaped upon being
impregnated with a liquid plastic monomer which can be converted by
heat, for example, or other forms of energy to a flexible solid.
The lower portion of the pile is then heat set into a relatively
rigid configuration after which the uncured upper portions of said
threads are subjected simultaneously to pressure and heat to bend
the threads into hooks extending randomly in all directions and
heat setting the upper portions into relatively permanent hook
shapes. More particularly, pressure and heat are applied by a
controlled flow of gaseous or liquid material whose temperature is
sufficient to accomplish heat setting.
It will be appreciated that hooking elements formed by this method
assume open hook configurations without the stubs commonly found in
hooking elements made by cutting loops. Also, the controlled flow
of gaseous or liquid material insured that the hooking elements
will be subjected to pressure in a variety of different directions
thereby resulting in ultimate hooks which extend in random
directions and so have a greater probability of interengagement
with mating looped elements.
Other advantages and novel features of this invention which have
not been heretofore described will become apparent from a reading
of the following detailed description taken in conjunction with the
accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the various steps of the method
herein described;
FIGS. 2, 3 and 4 are elevational views of the starting material
showing in sequence the various steps of the method of this
invention;
FIG. 5 is an isometric view of the finished product produced by the
method of the invention; and
FIG. 6 is a composite elevational view of a suitable apparatus for
carrying out the method of this invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring initially to FIG. 2, it will be seen that the starting
material 1 is a length of flexible material comprising a foundation
2 in which is securely anchored a pile of upstanding threads 3
arranged in random fashion over the surface of said foundation in
such a manner as to form a unitary structure with the latter. Any
one of many commercially available pile fabrics of the type
described may be used as the starting material. For instance,
upstanding threads made of cotton or one of the synthetic textiles
can be used, the choice being determined by the absorbability of
the pile and by the ultimate strength desired between the hook and
loop engaging surfaces of the separable fastener. In other words,
the yield strength of the upstanding threads 3 and foundation 2
should be greater than the greatest possible force to which the
separable fastener may be subjected thereby insuring that the pile
threads 3 or foundation 2 will not break and that the threads 3
will not rupture out of their anchored position in the foundation
2.
The starting material 1 is to be supplied on a reel 4 such as that
shown in FIG. 6 and is directed past an impregnating means 5 and
then fed around rollers 6, 7 and 8 in the manner indicated in FIG.
6 whereby the pile threads are upstanding from that surface on the
starting material which is not in contact with said rollers, and
ultimately wound on takeoff spool 10.
The starting material 1 is driven in the direction of arrow 20 by
any suitable means (not shown) thereby following the winding path
defined by said rollers. As the starting material proceeds around
said path, it will successively pass through the various processing
zones in each of which a step of the method contemplated by this
invention is performed. It should be noted that the apparatus shown
in the drawings for accomplishing the method of this invention is
not, in any way, to be construed as limited to the specific
apparatus therein shown. But rather, the specific apparatus
depicted in the drawings is included for purposes of illustration
only, and accordingly, any other suitable apparatus may be provided
without departing from the spirit of this invention.
The impregnating means 11 is shown diagrammatically as constituting
a tank and squeeze rollers 12 suitable for applying liquid material
to the pile threads. The liquid material should be sufficiently low
in viscosity to impregnate the pile threads 3 while, at the same
time, be adapted to later become rigid upon subjection to a
suitable heat treatment. Suitable impregnating liquids for this
purpose consist of any of the well-known thermosetting substances
such as epoxy resins, melamine resins, nylon monomer, plastisol or
an appropriate thermal-setting polyvinyl resin.
After impregnation with the resins the starting material continues
to travel in the direction of arrow 20 around roller 6 and enters
the heating zone indicated generally at 15 in which is stationed an
appropriate heat source 13 positioned above the starting material.
The heat source 13 can be of any suitable type which will direct a
flow of heat downward into contact with that side of the foundation
material opposite to the side carrying the pile threads 3. It will
be understood that the invention contemplates using various forms
of energy such as radiation energy, for example, to convert the
liquid impregnant to a flexible solid.
The speed at which the starting material travels is such that any
given portion of the starting material will be subjected to heat
for a predetermined precise period of time. It will be appreciated
that this arrangement will permit the heat generated by the heat
source 13 to penetrate the underside of the foundation material 2
and become transmitted gradually by conduction to the pile threads
3 so as to cure only a portion at a time of each thread, starting
of course with the portion of each thread located immediately
adjacent to the foundation material and proceeding downward to each
consecutive portion of the pile threads. Thus, as shown in FIG. 3,
the lower portion 16 of each pile thread is set into a relatively
straight configuration while the upper portion 17 of each pile
thread remains uncured conforming to its original configuration as
shown in FIG. 2.
As the starting material continues its journey in the direction of
arrow 20, it will pass around roller 7 during which time it will be
allowed to cool thereby setting the lower cured portion 16 of each
pile thread 3 into a relatively straight permanent shape. It will
be readily apparent that as the starting material proceeds, the
roller 7 causes it to be gradually inverted so that the pile
threads now project upward in which position they are ready to be
formed into hooks.
Because of the inverted position of the starting material, the
upper uncurved portion 17 of some of the pile threads 3 will fall
over under the influence of gravity to form substantially
hook-shaped elements 18. For the most part though, the pile threads
will remain in a substantially upright position and therefore in
order to bend these pile threads into hooks, a controlled flow of
air is directed by blowers 21 over the thread in the direction
indicated by arrows 25 and 26 of FIG. 4. It will be understood,
however, according to the method of the present invention that
fluids generally may be used.
The blowers are strategically positioned above the pile threads 3
so that the cross currents of air are set up in a variety of
different directions over the surface of the pile threads. The
pressure exerted by the air flow is of sufficient magnitude to
cause the upper uncured portion 17 of the pile threads 3 to bend
over into hook-shaped formations 18 which are best seen in FIGS. 4
and 5. Furthermore, the air or gaseous material is heated to
sufficiently high temperature to finish the cure and heat set the
upper portion of each pile thread into a relatively permanent hook
shape. The heating of the air can be accomplished by any suitable
means, such as, for instance, a second heater shown
diagrammatically at 22, which communicated with air blowers 21.
After subjection to the controlled flow of hot gaseous material,
the starting material, which now has a pile of upstanding
hook-shaped elements disposed over the surface thereof, is wound on
takeoff spool 10 in which form it can be transported to an
appropriate facility for further processing in accordance with its
ultimate intended application.
Thus, in summary, it will be seen that the method of this invention
produces a flexible strip of material in which are anchored a
multiplicity of open, reinforced, flexible hooks 18 which extend
randomly in a variety of different directions and which are
particularly suitable for use as the hooked member of a separable
hook or loop fastener referred to above. Since the planes of the
open hooks form angles with each other which vary in accordance
with the laws of statistical distribution, it will be apparent that
the probability of engagement with loops of the mating member is
greatly increased thereby increasing the adhesive strength of the
separable fastener with which the strip is intended for use.
While a preferred specific embodiment of the invention has been
heretofore described, it is to be clearly understood that various
modifications can be made in the details of the invention without
departing from the spirit of the invention or from the scope of the
appended claims.
* * * * *